JP7596876B2 - Resin and its molded body - Google Patents

Description

The present invention relates to a resin that has a small absolute value of orientation birefringence, high thermal stability, and a high refractive index and high heat resistance, a resin composition containing this resin, and a molded article made of the resin that is suitable as an optical component.

Polycarbonate resins are used as optical molding materials because of their excellent transparency, dimensional stability, mechanical properties, etc. Patent Document 1 discloses polycarbonate resins that mainly contain repeating units having a 9,9-bisphenylfluorene skeleton as polycarbonate resins with excellent optical properties.
In the examples of Patent Document 1, a polycarbonate resin is prepared using 2,2'-[9H-fluoren-9-ylidenebis(4,1-phenyleneoxy)]-bisethanol [9,9-bis[4-(2-hydroxyethoxy)phenyl]fluorene (abbreviation: BPEF)] as a polymerization component.

Patent Document 2 discloses a thermoplastic resin having a specific divalent oligofluorene structure as a repeating unit. As a second embodiment, Patent Document 2 discloses a thermoplastic resin having an oligofluorene structure and a structure derived from a divalent phenol compound in the repeating unit.

Patent Document 3 discloses a thermoplastic resin having a specific divalent oligofluorene structure as a repeating unit.

Patent Document 4 discloses a polyester resin that combines dicarboxylic acid units having an oligofluorene skeleton and diol units having a 9,9-bisarylfluorene skeleton.

Japanese Patent Application Publication No. 10-101787 JP 2017-075256 A JP 2017-075255 A JP 2018-172659 A

However, the polycarbonate resin described in Patent Document 1 has poor thermal stability because its main skeleton contains carbonate bonds derived from aliphatic hydroxy compounds, and the temperatures at which it can be manufactured, melt processed, and used as a molded product may be limited.

Furthermore, Patent Document 2 describes that the content of the structural unit derived from the dihydric phenol compound in the resin is not limited, and that if the content of the structural unit derived from the dihydric phenol compound is large, the processability may be impaired, and it is difficult to adjust the balance of physical properties such as optical properties and mechanical properties. For this reason, Patent Document 2 describes that the content of the structural unit derived from the dihydric phenol compound in the resin is particularly preferably 30% by weight or less.
Furthermore, although the examples in Patent Document 2 list a resin containing a structural unit derived from a dihydric phenol compound, the content is 33.2% by weight, and no specific disclosure is made of a resin containing 40% by weight or more. Moreover, the specifically disclosed resin has a large negative orientation birefringence.
In other words, Patent Document 2 does not contain any description suggesting that, in a resin having a divalent oligofluorene structure as a repeating unit, by appropriately selecting the content of structural units derived from a dihydric phenol compound, it is possible to design a resin having small birefringence and high thermal stability in the resulting molded article.

Furthermore, Patent Document 3 does not limit the content of structural units derived from aromatic dihydroxy compounds such as dihydric phenol compounds in the resin, and it is described that the content of aromatic structures other than oligofluorene structural units is preferably 10% by weight or less.
Furthermore, the examples of Patent Document 3 disclose only resins having a content of structural units derived from dihydric phenol compounds of 10% by weight or less. In the examples, the resin using isosorbide as the dihydroxy compound has a low refractive index of less than 1.59, and the resin using BPEF as the dihydroxy compound uses an aliphatic hydroxy compound, and therefore has poor thermal stability, and the temperatures for production, melt processing, and use of molded products may be limited.
Patent Document 3 also makes no disclosure suggesting that by appropriately selecting the content of structural units derived from a dihydric phenol compound in a resin having a divalent oligofluorene structure as a repeating unit, it is possible to design a resin having small birefringence and high thermal stability for the resulting molded article.

In addition, the resin in Patent Document 4 has a high refractive index and low birefringence, but because it uses aliphatic hydroxy compounds such as BPEF and 9,9-bis[6-(2-hydroxyethoxy)-2-naphthyl]fluorene (abbreviation: BNEF) as diol units, it has poor thermal stability and the temperatures at which it can be manufactured, melt processed, and used as a molded product may be limited.

The object of the present invention is to provide a resin that has high thermal stability enabling injection molding over a wide temperature range while maintaining high heat resistance and a high refractive index useful as an optical molding material, and has low birefringence and high moldability useful as an optical molding material, as well as a resin composition containing the resin and a molded product thereof.

As a result of intensive research aimed at solving the above-mentioned problems, the present inventors have discovered that at least one resin selected from the group consisting of polyester carbonates and polyesters, which contains a specific divalent oligofluorene structure and a specific amount of a structure derived from an aromatic dihydroxy compound in which a hydroxy group is directly bonded to an aromatic group, has excellent thermal stability and low birefringence, and also has a high refractive index and high heat resistance, thereby arriving at the present invention.
That is, the gist of the present invention lies in the following [1] to [17].

[1] At least one resin selected from the group consisting of polyester carbonates and polyesters, containing a structural unit represented by the following formula (1) and a structural unit represented by the following formula (2):
A resin containing 40% by weight or more of a structural unit represented by the following formula (2), when the total weight of the resin is taken as 100% by weight.

(In formula (1), R ¹¹ to R ¹³ are each independently a direct bond or an alkylene group having 1 to 4 carbon atoms which may have a substituent, and R ¹⁴ to R ¹⁹ are each independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms which may have a substituent, an aryl group having 6 to 10 carbon atoms which may have a substituent, an acyl group having 1 to 10 carbon atoms which may have a substituent, an amino group which may have a substituent, an alkenyl group having 2 to 10 carbon atoms which may have a substituent, an alkynyl group having 2 to 10 carbon atoms which may have a substituent, an oxygen atom which has a substituent, a sulfur atom which has a substituent, a silicon atom which has a substituent, a halogen atom, a nitro group, or a cyano group; however, at least two adjacent groups among R ¹⁴ to R ¹⁹ may be bonded to each other to form a ring.)

(In formula (2), Ar ¹ represents an unsubstituted or substituted aromatic hydrocarbon group having 6 to 88 carbon atoms, or a divalent group having 6 to 88 carbon atoms to which an unsubstituted or substituted aromatic hydrocarbon ring is linked via a direct bond or any linking group, and each of the two oxygen atoms shown in formula (2) represents that it is directly bonded to the same or different aromatic hydrocarbon ring in Ar ^1. )

[2] The resin according to [1], in which the content of the structural unit represented by formula (1) is 5% by weight or more when the total weight of the resin is 100% by weight.

[3] The resin according to [1] or [2], in which the total content of the structural unit represented by formula (1) and the structural unit represented by formula (2) is 80% by weight or more when the total weight of the resin is 100% by weight.

[4] The resin according to any one of [1] to [3], wherein the formula (2) is represented by the following formula (3):

(In formula (3), rings Z ¹ and Z ² each independently represent an aromatic hydrocarbon ring. ^{R 1} and R ² each independently represent an unsubstituted or substituted alkyl group having 1 to 10 carbon atoms, an unsubstituted or substituted aromatic hydrocarbon group having 6 to 10 carbon atoms, an unsubstituted or substituted acyl group having 1 to 10 carbon atoms, an oxygen atom having a substituent, a sulfur atom having a substituent, a silicon atom having a substituent, or a halogen atom. a and b each independently represent an integer of 0 or more. When a and b are 2 or more and there are multiple R ^1s and multiple R ^2s , the multiple R ^1s and R ^2s may be the same as or different from each other. At least two of the multiple R ^1s and/or R ^2s may be bonded to each other to form a ring. Y represents a single bond, a hydrocarbon group having 1 to 44 carbon atoms which may contain an aromatic group, O, S, S-S, SO, SO ₂ , or CO group.)

[5] The resin according to [4], wherein, in the formula (3), Y is a single bond, a hydrocarbon group having 1 to 44 carbon atoms which may contain an aromatic group, S, S-S, SO, or _SO2 .

[6] The resin according to [5], wherein in the formula (3), Y is a single bond, S, S--S, SO, _SO2 , or a group represented by any one of the following formulae (Y1) to (Y3) (wherein the * marks in the following formulae (Y1) to (Y3) indicate the bonding sites with the rings ^Z1 and ^Z2 in the formula (3)).

(In formula (Y1), R ³ and R ⁴ each independently represent a hydrogen atom or an unsubstituted or substituted alkyl group having 1 to 10 carbon atoms.)

(In formula (Y2), R ⁵ is a hydrogen atom or an unsubstituted or substituted alkyl group having 1 to 10 carbon atoms. R ⁶ is an unsubstituted or substituted aromatic hydrocarbon group having 1 to 10 carbon atoms, an unsubstituted or substituted aromatic hydrocarbon group having 6 to 10 carbon atoms, an unsubstituted or substituted acyl group having 1 to 10 carbon atoms, or a halogen atom. c represents an integer of 0 to 5. When c is 2 or more and there are multiple R ^6s , the multiple R ^6s may be the same or different. In addition, at least two groups among the multiple R ^6s may be bonded to each other to form a ring.)

(In formula (Y3), R ⁷ and R ⁸ each independently represent an unsubstituted or substituted alkyl group having 1 to 10 carbon atoms, an unsubstituted or substituted aromatic hydrocarbon group having 6 to 10 carbon atoms, an unsubstituted or substituted acyl group having 1 to 10 carbon atoms, or a halogen atom. d and e each independently represent an integer of 0 to 5. When d and e are 2 or more and there are a plurality of R ^7s and R ^8s , the plurality of R ^7s and R ^8s may be the same or different. Furthermore, at least two of the plurality of R ^7s and/or R ^8s may be bonded to each other to form a ring.)

[7] The resin according to [6], wherein the formula (3) is at least one selected from the group consisting of the following formulas (3-1) to (3-5):

(In formulas (3-1) to (3-5), R ¹ , R ² , a, and b are defined as in formula (3). In formula (3-4), R ⁶ and c are defined as in formula (Y2). In formula (3-5), R ⁷ , R ⁸ , d, and e are defined as in formula (Y2).)

[8] The resin according to [7], wherein the formula (3) is at least one selected from the group consisting of the following formulas (3-6) to (3-10):

[9] A resin according to any one of [1] to [8], having a refractive index of 1.59 or more at a wavelength of 589 nm.

[10] The resin according to any one of [1] to [9], having an Abbe number νD of 35.0 or less.

[11] A resin according to any one of [1] to [10], in which a stretched film made from the resin has an in-plane orientation birefringence of -0.0010 or more and 0.0020 or less at a wavelength of 550 nm.

[12] A resin according to any one of [1] to [11], which has a 1% thermal weight loss temperature (Td) under nitrogen of 355°C or higher.

[13] A resin according to any one of [1] to [12], having a glass transition temperature (Tg) of 110°C or higher and 250°C or lower.

[14] A resin composition containing the resin according to any one of [1] to [13] and at least one additive selected from the group consisting of a heat stabilizer, an antioxidant, an ultraviolet absorber, a brightness enhancer, a dye, a pigment, a release agent, a flow modifier, and an impact resistance improver.

[15] A resin composition comprising the resin according to any one of [1] to [13] or the resin composition according to [14], and further comprising another resin.

[16] A molded article obtained by molding the resin according to any one of [1] to [13] or the resin composition according to [14] or [15].

[17] The molded article according to [16], wherein the molded article is an optical component.

[18] The molded body according to [17], wherein the optical component is at least one optical lens selected from the group consisting of an in-vehicle lens, a spectacle lens, a pickup lens, a camera lens, a microarray lens, a projector lens, and a Fresnel lens.

The resin of the present invention has a structural unit represented by formula (1) and a structural unit represented by formula (2), and by containing the structural unit represented by formula (2) in a specific ratio, it is possible to design a resin that has low birefringence and high thermal stability in the resulting molded product. As a result, while maintaining high heat resistance and a high refractive index useful as an optical molding material, it has high thermal stability that allows injection molding over a wide temperature range, and low birefringence and high moldability useful as an optical molding material.

The resin of the present invention has high thermal stability, a small absolute value of orientation birefringence, and the birefringence of the resulting molded article is low, and the resin has a high refractive index and high heat resistance.
Therefore, the resin of the present invention and the resin composition of the present invention containing the resin can be easily processed into optical components by a method such as injection molding.
These optical members have a high refractive index and low birefringence while maintaining high thermal stability and high heat resistance, and are therefore useful as high-performance optical members.

Hereinafter, the present invention will be described in detail with reference to embodiments and examples, but the present invention should not be construed as being limited to the embodiments and examples shown below.
In this specification, unless otherwise specified, the term "to" is used to mean that the numerical values before and after it are included as the lower and upper limits. Furthermore, the term "structural unit" refers to a partial structure sandwiched between adjacent linking groups in a polymer, and a partial structure sandwiched between a polymerization reactive group present at the terminal portion of a polymer and a linking group adjacent to the polymerization reactive group.

In addition, in the present invention, a polycarbonate resin refers to a resin in which the structural units constituting the resin contain a portion (carbonate group) in which the structural units constituting the resin are linked by carbonate bonds. A polyester resin refers to a resin in which the structural units constituting the resin contain a portion (ester group) in which the structural units constituting the resin are linked by ester bonds. The resin of the present invention may be a polyester carbonate resin having a carbonate group and an ester group.

[resin]
The resin of the present invention is at least one resin selected from the group consisting of polyester carbonates and polyesters, which contains a structural unit represented by the following formula (1) (hereinafter may be referred to as "structural unit (1)") and a structural unit represented by the following formula (2) (hereinafter may be referred to as "structural unit (2)"), and is characterized in that, when the total weight of the resin is taken as 100% by weight, the resin contains 40% by weight or more of the structural unit (2).

(In formula (1), R ¹¹ to R ¹³ are each independently a direct bond or an alkylene group having 1 to 4 carbon atoms which may have a substituent, and R ¹⁴ to R ¹⁹ are each independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms which may have a substituent, an aryl group having 6 to 10 carbon atoms which may have a substituent, an acyl group having 1 to 10 carbon atoms which may have a substituent, an amino group which may have a substituent, an alkenyl group having 2 to 10 carbon atoms which may have a substituent, an alkynyl group having 2 to 10 carbon atoms which may have a substituent, an oxygen atom which has a substituent, a sulfur atom which has a substituent, a silicon atom which has a substituent, a halogen atom, a nitro group, or a cyano group; however, at least two adjacent groups among R ¹⁴ to R ¹⁹ may be bonded to each other to form a ring.)

(In formula (2), Ar ¹ represents an unsubstituted or substituted aromatic hydrocarbon group having 6 to 88 carbon atoms, or a divalent group having 6 to 88 carbon atoms to which an unsubstituted or substituted aromatic hydrocarbon ring is linked via a direct bond or any linking group, and each of the two oxygen atoms shown in formula (2) represents that it is directly bonded to the same or different aromatic hydrocarbon ring in Ar ^1. )

Many polymers have positive intrinsic birefringence, but oligofluorene structural units have negative intrinsic birefringence. It is believed that by adjusting the ratio of structural units with positive intrinsic birefringence and structural units with negative intrinsic birefringence in the resin, it is possible to make the birefringence of the resin almost zero. Since oligofluorene structural units have a relatively large negative intrinsic birefringence, the birefringence of the resin can be adjusted to zero with a small content, and therefore structural units derived from aromatic dihydroxy compounds in which hydroxy groups are directly bonded to aromatic groups can be incorporated into the resin, which is believed to improve the thermal stability and heat resistance of the resin. In addition, since this oligofluorene structural unit has a high density of aromatic structures, it is believed that it can be used suitably in cases where a high refractive index is required, such as in optical lens applications.

The contents of structural unit (1), structural unit (2), and other structural units described below in the resin can be determined by the method described in the Examples section below.

<Structural unit (1)>
In the formula (1) representing the structural unit (1), R ¹¹ and R ¹² are each independently a direct bond or an alkylene group having 1 to 4 carbon atoms which may have a substituent. The substituent here is not particularly limited as long as it does not impair the effects of the present invention, but is preferably selected from an alkyl group having 1 to 3 carbon atoms and a halogen atom. As the alkylene group having 1 to 4 carbon atoms which may have a substituent of R ¹¹ and R ¹² , for example, the following alkylene groups can be used.

Straight-chain alkylene groups, such as a methylene group, an ethylene group, an n-propylene group, or an n-butylene group; and branched-chain alkylene groups, such as a methylmethylene group, a dimethylmethylene group, an ethylmethylene group, a propylmethylene group, a (1-methylethyl)methylene group, a 1-methylethylene group, a 2-methylethylene group, a 1-ethylethylene group, a 2-ethylethylene group, a 1-methylpropylene group, a 2-methylpropylene group, a 1,1-dimethylethylene group, a 2,2-dimethylpropylene group, or a 3-methylpropylene group.
Chloromethylene group, dichloromethylene group, 1-chloroethylene group, 2-chloroethylene group, 1,1-dichloroethylene group, 2,2-dichloroethylene group, 1,2-dichloroethylene group, 1,1,2-trichloroethylene group, 1,2,2-trichloroethylene group, 1,1,2,2-tetrachloroethylene group, 1-chloro-n-propylene group, 1-chloro-n-butylene group, chloromethylmethylene group, chloroethylmethylene group, chloropropylmethylene group, chloro(1-methylethyl ) alkylene groups having a chloro group, such as a methylene group, a 1-chloro-1-methylethylene group, a 2-chloro-1-methylethylene group, a 1-chloro-2-methylethylene group, a 2-chloro-2-methylethylene group, a 1-chloro-1-ethylethylene group, a 2-chloro-1-ethylethylene group, a 1-chloro-2-ethylethylene group, a 2-chloro-2-ethylethylene group, or a 2-chloro-1,1-dimethylethylene group; and alkylene groups having a bromo group in which the chloro group is replaced with a bromo group.
Here, the positions of the branched chains and substituents in R ¹¹ and R ¹² are indicated by numbers given so that the carbon on the fluorene ring side is at the 1st position.

The selection of R ¹¹ and R ¹² has a particularly important effect on the development of negative birefringence. The largest negative birefringence is developed when the fluorene ring in the oligofluorene structural unit is oriented perpendicular to the main chain direction (stretching direction). In order to bring the orientation state of the fluorene ring closer to the above state and develop a large negative birefringence, it is preferable to adopt R ¹¹ and R ¹² in which the number of carbon atoms on the main chain of the alkylene group is 2 to 3, and it is more preferable to adopt R ¹¹ and R ¹² in which the number of carbon atoms is 2. When the number of carbon atoms is 1, there are cases where negative birefringence is not shown. This may be due to the steric hindrance of the carbonate group or ester group, which is the linking group of the oligofluorene structural unit, causing the orientation of the fluorene ring to be fixed in a direction that is not perpendicular to the main chain direction. On the other hand, when the number of carbon atoms is too large, the fixation of the orientation of the fluorene ring is weakened, which may weaken the negative birefringence. In addition, the heat resistance of the resin also tends to decrease. From the viewpoints of excellent optical characteristics and various physical properties and ease of production, R ¹¹ and R ¹² are preferably linear alkylene groups, more preferably propylene groups and ethylene groups, and particularly preferably ethylene groups.

As shown in the formula (1), R ¹¹ and R ¹² have one end of an alkylene group bonded to a fluorene ring, and the other end bonded to a carbonyl carbon, so that they have excellent thermal stability, heat resistance, and negative birefringence.As described later, as a monomer having an oligofluorene structure, specifically, a dihydroxy compound or a diester compound (hereinafter, diester also includes dicarboxylic acid) structure can be considered, but it is preferable to use a diester compound as a raw material to induce the structural unit (1).In addition, from the viewpoint of facilitating production, it is preferable to adopt the same alkylene group for R ¹¹ and R ¹² .

In the formula (1) representing the structural unit (1), R ¹³ is a direct bond or an alkylene group having 1 to 4 carbon atoms which may have a substituent. The substituent here is not particularly limited as long as it does not impair the effects of the present invention, but is preferably selected from an alkyl group having 1 to 3 carbon atoms and a halogen atom. As the alkylene group having 1 to 4 carbon atoms which may have a substituent of ^{R 13} , for example, the following alkylene groups can be used.

Straight-chain alkylene groups such as a methylene group, an ethylene group, an n-propylene group, or an n-butylene group; and branched-chain alkylene groups such as a methylmethylene group, a dimethylmethylene group, an ethylmethylene group, a propylmethylene group, a (1-methylethyl)methylene group, a 1-methylethylene group, a 2-methylethylene group, a 1-ethylethylene group, a 2-ethylethylene group, a 1-methylpropylene group, a 2-methylpropylene group, a 1,1-dimethylethylene group, a 2,2-dimethylpropylene group, or a 3-methylpropylene group.
Chloromethylene group, dichloromethylene group, 1-chloroethylene group, 2-chloroethylene group, 1,1-dichloroethylene group, 2,2-dichloroethylene group, 1,2-dichloroethylene group, 1,1,2-trichloroethylene group, 1,2,2-trichloroethylene group, 1,1,2,2-tetrachloroethylene group, 1-chloro-n-propylene group, 1-chloro-n-butylene group, chloromethylmethylene group, chloroethylmethylene group, chloropropylmethylene group, chloro(1-methylethyl ) alkylene groups having a chloro group, such as a methylene group, a 1-chloro-1-methylethylene group, a 2-chloro-1-methylethylene group, a 1-chloro-2-methylethylene group, a 2-chloro-2-methylethylene group, a 1-chloro-1-ethylethylene group, a 2-chloro-1-ethylethylene group, a 1-chloro-2-ethylethylene group, a 2-chloro-2-ethylethylene group, or a 2-chloro-1,1-dimethylethylene group; and alkylene groups having a bromo group in which the chloro group is replaced with a bromo group.

R ¹³ is preferably an alkylene group having 1 to 2 carbon atoms on the main chain, and particularly preferably has 1 carbon atom. When R ¹³ having too many carbon atoms on the main chain is used, the fixation of the fluorene ring is weakened, as in the case of R ¹¹ and R ¹² , and this may lead to a decrease in negative birefringence, an increase in the photoelastic coefficient, a decrease in heat resistance, and the like. On the other hand, the fewer the carbon atoms on the main chain, the better the optical properties and heat resistance, but when the 9-positions of the two fluorene rings are connected by a direct bond, the thermal stability is deteriorated. From the viewpoints of excellent optical properties and various physical properties and ease of production, R ¹³ is preferably an unsubstituted linear alkylene group, more preferably an ethylene group or a methylene group, and particularly preferably a methylene group.

In the formula (1) representing the structural unit (1), R ¹⁴ to R ¹⁹ are each independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms which may have a substituent, an aryl group having 6 to 10 carbon atoms which may have a substituent, an acyl group having 1 to 10 carbon atoms which may have a substituent, an amino group which may have a substituent, an alkenyl group having 2 to 10 carbon atoms which may have a substituent, an alkynyl group having 2 to 10 carbon atoms which may have a substituent, an oxygen atom which has a substituent, a sulfur atom which has a substituent, a silicon atom which has a substituent, a halogen atom, a nitro group, or a cyano group. However, at least two adjacent groups among R ¹⁴ to R ¹⁹ may be bonded to each other to form a ring. The substituent here is not particularly limited as long as it does not impede the effects of the present invention, but is preferably selected from an alkyl group having 1 to 10 carbon atoms, an aromatic hydrocarbon group having 6 to 10 carbon atoms, and a halogen atom.

The alkyl group having 1 to 10 carbon atoms which may have a substituent of ^R to R ¹⁹ may be linear, branched, or cyclic. As the alkyl group having 1 to 10 carbon atoms which may have a substituent, for example, the following alkyl groups can be used.
Methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl group, n-hexyl group, cyclohexyl group, n-heptyl group, n-octyl group, n-nonyl group, n-decyl group; alkyl groups having a chloro group such as a chloromethyl group, a dichloromethyl group, a trichloromethyl group, a 1-chloroethyl group, a 2-chloroethyl group, a 1-chloropropyl group, a 1-chloroisopropyl group, a 1-chloro-n-butyl group, a 2-chloro-tert-butyl group, or a 1-chloro-cyclohexyl group; and alkyl groups having a bromo group in which the chloro group is replaced with a bromo group.

Examples of the aryl group having 6 to 10 carbon atoms which may have a substituent of R ¹⁴ to R ¹⁹ include unsubstituted phenyl and naphthyl groups. Examples of those having a substituent include methylphenyl (tolyl), ethylphenyl, propylphenyl, butylphenyl, dimethylphenyl, trimethylphenyl, chlorophenyl, and bromophenyl groups. From the viewpoint of the thermal stability and heat resistance of the resin of the present invention, unsubstituted ones are preferred.

Examples of the acyl group having 1 to 10 carbon atoms which may have a substituent represented by R ¹⁴ to R ¹⁹ include a methanoyl group, an ethanoyl group, a propanoyl group, a butanoyl group, a pentanoyl group, a hexanoyl group, a heptanoyl group, an octanoyl group, a nonanoyl group, a decanoyl group, a benzoyl group, an acrylyl group, a chloroethanoyl group, a dichloroethanoyl group, a trichloroethanoyl group, a bromoethanoyl group, and a fluoroethanoyl group.

The amino groups which may have a substituent of R ¹⁴ to R ¹⁹ include an NH ₂ group as an unsubstituted group. In addition, examples of the amino groups which have a substituent include a dialkylamino group; a bis(alkylcarbonyl)amino group, and the like. Examples of the dialkylamino group include a diC _1-4 alkylamino group such as a dimethylamino group. Examples of the bis(alkylcarbonyl)amino group include a bis(C _1-4 alkyl-carbonyl)amino group such as a diacetylamino group.

The alkenyl groups having 2 to 10 carbon atoms which may have a substituent of R ¹⁴ to R ¹⁹ may be linear, branched or cyclic. As the alkenyl group having 2 to 10 carbon atoms which may have a substituent, for example, the following alkenyl groups can be used.
ethenyl, propenyl, isopropenyl, n-butenyl, isobutenyl, pentenyl, n-hexenyl, cyclohexenyl, n-heptenyl, n-octenyl, n-nonenyl, n-decenyl; alkenyl groups having a chloro group, such as 1-chloroethenyl, 2-chloroethenyl, 1-chloropropenyl, 1-chloro-n-butenyl, and 2-chloro-cyclohexyl; and alkenyl groups having a bromo group in which the above-mentioned chloro group has been replaced with a bromo group.

The alkynyl groups of ^R to ^R which may have a substituent and have 2 to 10 carbon atoms may be linear, branched, or cyclic. As the alkynyl group of R to R which may have a substituent and have 2 to 10 carbon atoms, for example, the following alkynyl groups can be used.
ethynyl, propynyl, n-butynyl, pentynyl, n-hexynyl, cyclohexynyl, n-heptynyl, n-octynyl, n-nonynyl, n-decynyl; alkynyl groups having a chloro group, such as a chloroethynyl group, a 3-chloropropenyl group, or a 3-chloro-n-butenyl group; and alkynyl groups having a bromo group in which the chloro group is replaced with a bromo group.

Examples of the oxygen atom having a substituent of ^R to R ¹⁹ include a hydroxy group; an alkoxy group such as a methoxy group, an ethoxy group, a propyloxy group, a hexyloxy group, a cyclohexyloxy group, a heptyloxy group, an octyloxy group, a nonyloxy group, or a decyloxy group; an aryloxy group such as a phenoxy group or a benzyloxy group; an acyloxy group such as a methanoyloxy group, an ethanoyloxy group, a propanoyloxy group, a butanoyloxy group, a pentanoyloxy group, a hexanoyloxy group, a heptanoyloxy group, an octanoyloxy group, a nonanoyloxy group, a decanoyloxy group, a benzoyloxy group, an acrylyloxy group, a chloroethanoyloxy group, a dichloroethanoyloxy group, a trichloroethanoyloxy group, a bromoethanoyloxy group, or a fluoroethanoyloxy group; and an oxygen atom having a crosslinked structure with the same or different benzene rings on a fluorene skeleton described later.

Examples of the sulfur atom having a substituent of ^R to R ¹⁹ include a thiol group; alkylthio groups such as a methylthio group, an ethylthio group, a propylthio group, a hexylthio group, a cyclohexylthio group, a heptylthio group, an octylthio group, a nonylthio group, and a decylthio group; arylthio groups such as a phenylthio group and a benzylthio group; a sulfo group; and sulfur atoms having a crosslinking structure with the same or different benzene rings on a fluorene skeleton described later, and a sulfonyl group.

Examples of silicon atoms having substituents R ¹⁴ to R ¹⁹ include a silyl group, a monomethylsilyl group, a dimethylsilyl group, a trimethylsilyl group, a triethylsilyl group; and silicon atoms having the same or different benzene rings on a fluorene skeleton as described below as a crosslinking structure.

Examples of the halogen atom for R ¹⁴ to R ¹⁹ include a chlorine atom, a bromine atom, and a fluorine atom.

When at least two adjacent groups among R ¹⁴ to R ¹⁹ are bonded to each other to form a ring, examples thereof include the following.
(a) Two adjacent substituents ( ^R14 and ^R15 , R15 and ^R16 , ^R16 and ^R14 , ^R17 and ^R18 , ^R18 and ^R19 , ^R19 and ^R17 ) present on ^the same benzene ring of one fluorene skeleton are bonded to each other to form a fused ring fused to one benzene ring.
(b) Two adjacent substituents (R ¹⁶ and R ¹⁷ ) present on two different benzene rings on one fluorene skeleton are bonded to each other to form a bridge structure between the two benzene rings.
Specific examples of the above case (b) include crosslinked structures linking carbon atoms on two benzene rings with each other, such as -O-, -S-, -SO ₂ -, -Si-, -SiH ₂ -, -SiMe ₂ -, or -SiEt ₂ -.

The fluorene ring contained in the structural unit (1) is preferably either a structure in which all of R ¹⁴ to R ¹⁹ are hydrogen atoms, or a structure in which R ¹⁴ and/or R ¹⁹ are any one selected from the group consisting of a halogen atom, an acyl group, a nitro group, a cyano group, and a sulfo group, and R ¹⁵ to R ¹⁸ are hydrogen atoms. In the former structure, a compound containing the structural unit (1) can be derived from fluorene, which is industrially inexpensive. In the latter structure, the reactivity of the 9-position of fluorene is improved, and therefore various derivatization reactions tend to be applicable in the synthesis process of a compound containing the structural unit (1). The fluorene ring is more preferably either a configuration in which all of R ¹⁴ to R ¹⁹ are hydrogen atoms, or a configuration in which R ¹⁴ and/or R ¹⁹ are any selected from the group consisting of a fluorine atom, a chlorine atom, a bromine atom, and a nitro group, and R ¹⁵ to R ¹⁸ are hydrogen atoms, and particularly preferably a configuration in which all of R ¹⁴ to R ¹⁹ are hydrogen atoms. By adopting the above configuration, the fluorene ratio can be increased, and steric hindrance between the fluorene rings is unlikely to occur, and there is also a tendency that desired optical properties derived from the fluorene ring are obtained.

As the structural unit (1), structural units represented by the following formulas (1A) and (1B) are particularly preferred.

The resin of the present invention may contain only one type of structural unit (1), or may contain two or more types.

The content of structural unit (1) in the resin of the present invention is preferably 1% by weight or more, more preferably 5% by weight or more, even more preferably 10% by weight or more, and particularly preferably 20% by weight or more, when the total weight of the resin is 100% by weight. If the content of structural unit (1) is equal to or more than the above lower limit, the effect of reducing the birefringence of the resin due to the inclusion of structural unit (1) can be effectively obtained. On the other hand, the content of structural unit (1) in 100% by weight of the resin of the present invention is 60% by weight or less, preferably 56% by weight or less, more preferably 45% by weight or less, from the viewpoint of ensuring the content of structural unit (2).

An example of a monomer that can be used as a resin raw material to induce such structural unit (1) into a resin is a diester compound represented by the following formula (11).

(In formula (11), R ¹¹ to R ¹⁹ are defined the same as R ¹¹ to R ¹⁹ in formula (1). ^{A 1} and A ² are a hydrogen atom, an aliphatic hydrocarbon group having 1 to 18 carbon atoms which may have a substituent, or an aromatic hydrocarbon group which may have a substituent, and A 1 and A 2 may be the same or different.)

When A ¹ and A ² in the formula (11) are hydrogen atoms or aliphatic hydrocarbon groups such as methyl and ethyl groups, the polymerization reaction may be difficult to occur under the polymerization conditions of commonly used polycarbonate resins and polyester resins, and therefore A ¹ and A ² in the formula (11) are preferably aromatic hydrocarbon groups such as phenyl and tolyl groups, and particularly preferably phenyl groups.

[Structural unit (2)]
In the formula (2) representing the structural unit (2), Ar ¹ refers to an aromatic hydrocarbon group having 6 to 88 carbon atoms, which is unsubstituted or substituted, or a divalent group having 6 to 88 carbon atoms, to which an aromatic hydrocarbon ring having an unsubstituted or substituted group is directly bonded or linked by an arbitrary linking group. ^{Ar 1} may be a divalent group consisting of one aromatic hydrocarbon ring, or may be a group in which two or more aromatic hydrocarbon rings are bonded via a linking group or directly bonded. Here, the aromatic hydrocarbon ring may be a monocyclic ring or a condensed ring. In either case, it is important that the two oxygen atoms in formula (2) are directly bonded to the same or different aromatic hydrocarbon rings, and the thermal stability of the resin is improved by both oxygen atoms being directly bonded to the aromatic hydrocarbon ring.

The structural unit (2) is preferably a structural unit represented by the following formula (3) from the viewpoint of the balance of various physical properties, such as thermal stability, heat resistance, mechanical properties, and optical properties such as transparency, refractive index, and birefringence.

(In formula (3), rings Z ¹ and Z ² each independently represent an aromatic hydrocarbon ring. ^{R 1} and R ² each independently represent an unsubstituted or substituted alkyl group having 1 to 10 carbon atoms, an unsubstituted or substituted aromatic hydrocarbon group having 6 to 10 carbon atoms, an unsubstituted or substituted acyl group having 1 to 10 carbon atoms, an oxygen atom having a substituent, a sulfur atom having a substituent, a silicon atom having a substituent, or a halogen atom. a and b each independently represent an integer of 0 or more. When a and b are 2 or more and there are multiple R ^1s and multiple R ^2s , the multiple R ^1s and R ^2s may be the same as or different from each other. At least two of the multiple R ^1s and/or R ^2s may be bonded to each other to form a ring. Y represents a single bond, a hydrocarbon group having 1 to 44 carbon atoms which may contain an aromatic group, O, S, S-S, SO, SO ₂ , or CO group.)

In the above formula (3), rings ^Z1 and ^Z2 each independently represent an aromatic hydrocarbon ring. Examples of the aromatic hydrocarbon ring include a benzene ring, a naphthalene ring, and an anthracene ring. From the viewpoint of improving the fluidity of the resin, rings ^Z1 and ^Z2 each independently preferably represent a benzene ring or a naphthalene ring, and more preferably a benzene ring.

R ¹ and R ² are each independently an unsubstituted or substituted alkyl group having 1 to 10 carbon atoms, an unsubstituted or substituted aromatic hydrocarbon group having 6 to 10 carbon atoms, an unsubstituted or substituted acyl group having 1 to 10 carbon atoms, an oxygen atom having a substituent, a sulfur atom having a substituent, a silicon atom having a substituent, or a halogen atom. However, when a and b are 2 or more and there are a plurality of R ¹ and R ² , the plurality of R ¹ and R ² may be the same or different. Furthermore, at least two groups among the plurality of R ¹ and/or R ² may be bonded to each other to form a ring.

In the above, the substituent is not particularly limited as long as it does not interfere with the effects of the present invention, but is preferably selected from an alkyl group having 1 to 10 carbon atoms, an aromatic hydrocarbon group having 6 to 10 carbon atoms, and a halogen atom.

The unsubstituted or substituted alkyl group having 1 to 10 carbon atoms for R ¹ and R ² may be linear, branched, or cyclic. Examples of the unsubstituted or substituted alkyl group having 1 to 10 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, an n-hexyl group, a cyclohexyl group, an n-heptyl group, an n-octyl group, an n-nonyl group, and an n-decyl group.

Examples of the unsubstituted or substituted aromatic hydrocarbon groups having 6 to 10 carbon atoms for R ¹ and R ² include unsubstituted phenyl and naphthyl groups. Examples of substituted aromatic hydrocarbon groups include methylphenyl (tolyl), ethylphenyl, propylphenyl, butylphenyl, dimethylphenyl, and trimethylphenyl groups. From the viewpoint of the thermal stability and heat resistance of the resin of the present invention, unsubstituted aromatic hydrocarbon groups are preferred.

Examples of the unsubstituted or substituted acyl group having 1 to 10 carbon atoms for R ¹ and R ² include a methanoyl group, an ethanoyl group, a propanoyl group, a butanoyl group, a pentanoyl group, a hexanoyl group, a heptanoyl group, an octanoyl group, a nonanoyl group, a decanoyl group, a benzoyl group, an acrylyl group, a chloroethanoyl group, a dichloroethanoyl group, a trichloroethanoyl group, a bromoethanoyl group, and a fluoroethanoyl group.

Examples of the oxygen atom having a substituent of ^R1 or ^R2 include a hydroxy group; an alkoxy group such as a methoxy group, an ethoxy group, a propyloxy group, a hexyloxy group, a cyclohexyloxy group, a heptyloxy group, an octyloxy group, a nonyloxy group, a decyloxy group, a phenoxy group, or a benzyloxy group; and an oxygen atom forming a bridge structure between rings ^Z1 and ^Z2 described later.

Examples of the sulfur atom having a substituent of R ¹ or R ² include a thiol group; alkylthio groups such as a methylthio group, an ethylthio group, a propylthio group, a hexylthio group, a cyclohexylthio group, a heptylthio group, an octylthio group, a nonylthio group, and a decylthio group; arylthio groups such as a phenylthio group and a benzylthio group; a sulfo group; a sulfur atom bridging the ring Z ¹ and the ring Z ² described later, and a sulfonyl group.

Examples of the silicon atom having a substituent of R ¹ or R ² include a silyl group, a monomethylsilyl group, a dimethylsilyl group, a trimethylsilyl group, a triethylsilyl group, and a silicon atom forming a bridge structure between rings Z ¹ and Z ² described below.

Examples of the halogen atom for R ¹ and R ² include a chlorine atom, a bromine atom, and a fluorine atom.

When at least two groups of ^R1 and/or ^R2 are bonded to each other to form a ring, examples include the following.
(a) Adjacent R ¹ and R ¹ are bonded to each other to form a fused ring fused to ring Z ¹ .
(b) adjacent ^R2 and ^R2 are bonded to each other to form a fused ring fused to ring ^Z2 .
(c) ^R1 and ^R2 are bonded to form a bridge structure between ring ^Z1 and ring ^Z2 .
Specific examples of the above case (c) include a bridged structure linking a carbon atom on ring ^Z1 with a carbon atom on ring ^Z2 via -O-, -S-, _-SO2- , -Si-, _-SiH2- , _-SiMe2- , or _-SiEt2- (Me represents a methyl group, and Et represents an ethyl group).

Of these, R ¹ and R ² are preferably a methyl group, a cyclohexyl group, a phenyl group, or a naphthyl group, more preferably a methyl group, a cyclohexyl group, or a phenyl group, still more preferably a methyl group or a phenyl group, and particularly preferably a methyl group.

Each of a and b independently represents an integer of 0 or more. Of these, each of a and b independently represents an integer of 0 to 2, more preferably 0 or 1, and even more preferably 0.

Y is a single bond, a hydrocarbon group which may contain an aromatic group having 1 to 44 carbon atoms, O, S, S-S, SO, SO ₂ or CO group, but from the viewpoint of a balance of various physical properties such as heat resistance, mechanical properties, high refractive index, etc., it is preferably a single bond, a hydrocarbon group which may contain an aromatic group having 1 to 44 carbon atoms, S, S-S, SO or SO ₂ , and more preferably a single bond, S, S-S, SO, SO ₂ or a group represented by any of the following formulas (Y1) to (Y3) (wherein the * marks in the following formulas (Y1) to (Y3) indicate the bonds to the rings Z ¹ and Z ² in formula (3) above).

(In formula (Y1), R ³ and R ⁴ each independently represent a hydrogen atom or an unsubstituted or substituted alkyl group having 1 to 10 carbon atoms.)

(In formula (Y2), R ⁵ is a hydrogen atom or an unsubstituted or substituted alkyl group having 1 to 10 carbon atoms. R ⁶ is an unsubstituted or substituted aromatic hydrocarbon group having 1 to 10 carbon atoms, an unsubstituted or substituted aromatic hydrocarbon group having 6 to 10 carbon atoms, an unsubstituted or substituted acyl group having 1 to 10 carbon atoms, or a halogen atom. c represents an integer of 0 to 5. When c is 2 or more and there are multiple R ^6s , the multiple R ^6s may be the same or different. In addition, at least two groups among the multiple R ^6s may be bonded to each other to form a ring.)

(In formula (Y3), R ⁷ and R ⁸ each independently represent an unsubstituted or substituted alkyl group having 1 to 10 carbon atoms, an unsubstituted or substituted aromatic hydrocarbon group having 6 to 10 carbon atoms, an unsubstituted or substituted acyl group having 1 to 10 carbon atoms, or a halogen atom. d and e each independently represent an integer of 0 to 5. When d and e are 2 or more and there are a plurality of R ^7s and R ^8s , the plurality of R ^7s and R ^8s may be the same or different. Furthermore, at least two of the plurality of R ^7s and/or R ^8s may be bonded to each other to form a ring.)

In the above formula (Y1), R ³ and R ⁴ are each independently a hydrogen atom or an unsubstituted or substituted alkyl group having 1 to 10 carbon atoms. The unsubstituted or substituted alkyl group having 1 to 10 carbon atoms may be linear, branched, or cyclic. Examples of the unsubstituted or substituted alkyl group having 1 to 10 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, an n-hexyl group, a cyclohexyl group, an n-heptyl group, an n-octyl group, an n-nonyl group, and an n-decyl group.

R ³ and R ⁴ are each independently preferably a hydrogen atom, a methyl group, an ethyl group, or a cyclohexyl group, more preferably a hydrogen atom, a methyl group, or an ethyl group, still more preferably a hydrogen atom or a methyl group, and particularly preferably a methyl group.

In the above formula (Y2), ^R5 is a hydrogen atom or an unsubstituted or substituted alkyl group having 1 to 10 carbon atoms. The unsubstituted or substituted alkyl group having 1 to 10 carbon atoms may be linear, branched, or cyclic. Examples of the unsubstituted or substituted alkyl group having 1 to 10 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, an n-hexyl group, a cyclohexyl group, an n-heptyl group, an n-octyl group, an n-nonyl group, and an n-decyl group.

^R5 is preferably a hydrogen atom, a methyl group, an ethyl group, or a cyclohexyl group, more preferably a hydrogen atom, a methyl group, or an ethyl group, still more preferably a hydrogen atom or a methyl group, and particularly preferably a methyl group.

^R6 is an unsubstituted or substituted alkyl group having 1 to 10 carbon atoms, an unsubstituted or substituted aromatic hydrocarbon group having 6 to 10 carbon atoms, an unsubstituted or substituted acyl group having 1 to 10 carbon atoms, or a halogen atom, provided that at least two groups of ^R6 may be bonded to each other to form a ring.

In the above, the substituent is not particularly limited as long as it does not interfere with the effects of the present invention, but is preferably selected from an alkyl group having 1 to 10 carbon atoms, an aromatic hydrocarbon group having 6 to 10 carbon atoms, and a halogen atom.

The unsubstituted or substituted alkyl group having 1 to 10 carbon atoms represented by R ⁶ may be linear, branched, or cyclic. Examples of the unsubstituted or substituted alkyl group having 1 to 10 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, an n-hexyl group, a cyclohexyl group, an n-heptyl group, an n-octyl group, an n-nonyl group, and an n-decyl group.

Examples of the unsubstituted or substituted aromatic hydrocarbon group having 6 to 10 carbon atoms for ^R6 include unsubstituted phenyl and naphthyl groups. Substituted groups include methylphenyl (tolyl), ethylphenyl, propylphenyl, butylphenyl, dimethylphenyl, and trimethylphenyl groups. From the viewpoint of the thermal stability and heat resistance of the resin of the present invention, unsubstituted groups are preferred.

Examples of the unsubstituted or substituted acyl group having 1 to 10 carbon atoms for ^R6 include a methanoyl group, an ethanoyl group, a propanoyl group, a butanoyl group, a pentanoyl group, a hexanoyl group, a heptanoyl group, an octanoyl group, a nonanoyl group, a decanoyl group, a benzoyl group, an acrylyl group, a chloroethanoyl group, a dichloroethanoyl group, a trichloroethanoyl group, a bromoethanoyl group, and a fluoroethanoyl group.

Examples of the halogen atom for ^R6 include a chlorine atom, a bromine atom, and a fluorine atom.

When at least two groups among R ⁶ are bonded to each other to form a ring, for example, adjacent R ⁶ and R ⁶ are bonded to each other to form a fused ring fused to a benzene ring.

Of these, ^R6 is preferably a methyl group, a cyclohexyl group, a phenyl group, or a naphthyl group, more preferably a methyl group, a cyclohexyl group, or a phenyl group, still more preferably a methyl group or a phenyl group, and particularly preferably a methyl group.

c represents an integer of up to 5. Of these, c is preferably an integer of 0 to 2, more preferably 0 or 1, and even more preferably 0.

In the formula (Y3), R ⁷ and R ⁸ each independently represent an unsubstituted or substituted alkyl group having 1 to 10 carbon atoms, an unsubstituted or substituted aromatic hydrocarbon group having 6 to 10 carbon atoms, an unsubstituted or substituted acyl group having 1 to 10 carbon atoms, or a halogen atom, provided that at least two groups of R ⁷ and/or R ⁸ may be bonded to each other to form a ring.

In the above, the substituent is not particularly limited as long as it does not interfere with the effects of the present invention, but is preferably selected from an alkyl group having 1 to 10 carbon atoms, an aromatic hydrocarbon group having 6 to 10 carbon atoms, and a halogen atom.

The unsubstituted or substituted alkyl group having 1 to 10 carbon atoms for R ⁷ and R ⁸ may be linear, branched, or cyclic. Examples of the unsubstituted or substituted alkyl group having 1 to 10 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, an n-hexyl group, a cyclohexyl group, an n-heptyl group, an n-octyl group, an n-nonyl group, and an n-decyl group.

Examples of the unsubstituted or substituted aromatic hydrocarbon group having 6 to 10 carbon atoms for R ⁷ and R ⁸ include unsubstituted phenyl and naphthyl groups. Examples of substituted aromatic hydrocarbon groups include methylphenyl (tolyl), ethylphenyl, propylphenyl, butylphenyl, dimethylphenyl, and trimethylphenyl groups. From the viewpoint of the thermal stability and heat resistance of the resin of the present invention, unsubstituted aromatic hydrocarbon groups are preferred.

Examples of the unsubstituted or substituted acyl group having 1 to 10 carbon atoms for R ⁷ and R ⁸ include a methanoyl group, an ethanoyl group, a propanoyl group, a butanoyl group, a pentanoyl group, a hexanoyl group, a heptanoyl group, an octanoyl group, a nonanoyl group, a decanoyl group, a benzoyl group, an acrylyl group, a chloroethanoyl group, a dichloroethanoyl group, a trichloroethanoyl group, a bromoethanoyl group, and a fluoroethanoyl group.

Examples of the halogen atom for R ⁷ and R ⁸ include a chlorine atom, a bromine atom, and a fluorine atom.

When at least two groups of ^R7 and/or ^R8 are bonded to each other to form a ring, examples include the following.
(a) Adjacent ^R7 and ^R7 are bonded to each other to form a fused ring fused to a benzene ring.
(b) adjacent R ⁸ and R ⁸ are bonded to each other to form a fused ring fused to a benzene ring.
(c) ^R7 and ^R8 combine to form a bridge structure connecting the two benzene rings in formula (Y3).
Specific examples of the above case (c) include crosslinked structures linking carbon atoms on two benzene rings together, such as -O-, -S-, -SO ₂ -, -Si-, -SiH ₂ -, -SiMe ₂ -, or -SiEt ₂ -.

Of these, R ⁷ and R ⁸ are preferably a methyl group, a cyclohexyl group, a phenyl group, or a naphthyl group, more preferably a methyl group, a cyclohexyl group, or a phenyl group, still more preferably a methyl group or a phenyl group, and particularly preferably a methyl group.

d and e each independently represent an integer from 0 to 5. Of these, d and e each independently preferably represent an integer from 0 to 2, more preferably 0 or 1, and even more preferably 0.

The structural unit represented by the formula (3) is more preferably a structural unit represented by any one of the following formulas (3-1) to (3-5), and particularly preferably a structural unit represented by any one of the following formulas (3-6) to (3-10). Among these, the structural unit represented by any one of the following formulas (3-1), (3-2), (3-4), or (3-5) is even more preferable because the refractive index of the resin is high.

(In formulas (3-1) to (3-5), R ¹ , R ² , a, and b are defined as in formula (3). In formula (3-4), R ⁶ and c are defined as in formula (Y2). In formula (3-5), R ⁷ , R ⁸ , d, and e are defined as in formula (Y2).)

The resin of the present invention may contain only one type of structural unit (2), or may contain two or more types.

The content of structural unit (2) in the resin of the present invention is 40% by weight or more, preferably 50% by weight or more, more preferably more than 50% by weight, even more preferably 51% by weight or more, and particularly preferably 52% by weight or more, when the total weight of the resin is 100% by weight. If the content of structural unit (2) is equal to or more than the above lower limit, the effect of improving thermal stability and reducing birefringence due to the inclusion of structural unit (2) can be effectively obtained. On the other hand, the content of structural unit (2) in 100% by weight of the resin of the present invention is preferably 99% by weight or less, more preferably 95% by weight or less, even more preferably 90% by weight or less, and particularly preferably 80% by weight or less, from the viewpoint of ensuring the content of structural unit (1).

Examples of monomers that serve as resin raw materials for inducing such structural unit (2) into a resin include dihydroxy compounds represented by the following formulae (3-1A) to (3-5A), and it is particularly preferable that these dihydroxy compounds are dihydroxy compounds represented by the following formulae (3-6A) to (3-10A).

(In formulas (3-1A) to (3-5A), R ¹ , R ² , a, and b are defined as in formula (3). In formula (3-4A), R ⁶ and c are defined as in formula (Y2). In formula (3-5A), R ⁷ , R ⁸ , d, and e are defined as in formula (Y2).)

Specific examples of the raw material dihydroxy compound for inducing structural unit (2) in the resin of the present invention include the following.

(In the structural unit (2), when Ar ¹ is an unsubstituted or substituted aromatic hydrocarbon group having 6 to 88 carbon atoms)
Benzenediols such as hydroquinone, resorcinol, and catechol;
Naphthalenediols such as 1,2-dihydroxynaphthalene, 1,3-dihydroxynaphthalene, 1,4-dihydroxynaphthalene, 1,5-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 1,7-dihydroxynaphthalene, 1,8-dihydroxynaphthalene, 2,3-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, and 2,7-dihydroxynaphthalene;

(In the structural unit (2), when Ar ¹ is a divalent group having 6 to 88 carbon atoms in which an unsubstituted or substituted aromatic hydrocarbon ring is linked via a direct bond or any linking group)
1,1'-bi-2-naphthol, 2,2'-dihydroxy-3,3'-diphenyl-1,1'-binaphthalene, 2,2'-dihydroxy-4,4'-diphenyl-1,1'-binaphthalene, 2,2'-dihydroxy-5,5'-diphenyl-1,1'-binaphthalene, 2,2'-dihydroxy-6,6'-diphenyl-1,1'-binaphthalene, 2,2'-dihydroxy-7,7'-diphenyl phenyl-1,1'-binaphthalene, 2,2'-dihydroxy-8,8'-diphenyl-1,1'-binaphthalene, 2,2'-dihydroxy-3,3'-di-1-naphthyl-1,1'-binaphthalene, 2,2'-dihydroxy-4,4'-di-1-naphthyl-1,1'-binaphthalene, 2,2'-dihydroxy-5,5'-di-1-naphthyl-1,1'-binaphthalene, 2,2'-dihydro 2,2'-dihydroxy-7,7'-di-1-naphthyl-1,1'-binaphthalene, 2,2'-dihydroxy-8,8'-di-1-naphthyl-1,1'-binaphthalene, 2,2'-dihydroxy-3,3'-di-2-naphthyl-1,1'-binaphthalene, 2,2'-dihydroxy-4,4'-di-2-naphthyl-1,1'- Compounds having a binaphthyl skeleton, such as binaphthalene, 2,2'-dihydroxy-5,5'-di-2-naphthyl-1,1'-binaphthalene, 2,2'-dihydroxy-6,6'-di-2-naphthyl-1,1'-binaphthalene, 2,2'-dihydroxy-7,7'-di-2-naphthyl-1,1'-binaphthalene, and 2,2'-dihydroxy-8,8'-di-2-naphthyl-1,1'-binaphthalene;
Biphenol derivatives such as 4,4'-biphenol, 3,3'-dimethyl-4,4'-biphenol, 2,2',6,6'-tetramethylbiphenol, octamethylbiphenol, 3,3'-dichloro-4,4'-biphenol, 2,2',6,6'-tetrachlorobiphenol, octachlorobiphenol, 3,3'-dibromo-4,4'-biphenol, 2,2',6,6'-tetrabromobiphenol, and octabromobiphenol;

2,2-bis(4-hydroxyphenyl)propane, 2,2-bis(3-methyl-4-hydroxyphenyl)propane, 2,2-bis(4-hydroxy-3,5-dimethylphenyl)propane, 2,2-bis(4-hydroxy-3,5-diethylphenyl)propane, 2,2-bis(4-hydroxy-(3-phenyl)phenyl)propane, 2,2-bis(4-hydroxy-(3,5-diphenyl)phenyl)propane, 2,2-bis(4-hydroxy-3,5-dibromophenyl)propane, bis(4-hydroxyphenyl)methane, 1,1-bis(4-hydroxyphenyl)ethane, 1,1-bis(4-hydroxyphenyl)ethane, 1,1-bis(4-hydroxyphenyl)propane, 1,1-bis(4-hydroxyphenyl)butane, 2,2-bis(4-hydroxyphenyl)butane, 1,1-bis(4-hydroxyphenyl)pentane, 2,2-bis(4-hydroxyphenyl)pentane, 1,1-bis(4-hydroxyphenyl)hexane, 1,1-bis(4-hydroxyphenyl)heptane, 1,1-bis(4-hydroxyphenyl)octane, 1,1-bis(4-hydroxyphenyl)nonane, 1,1-bis(4-hydroxyphenyl)decane, 1,1-bis(4-hydroxyphenyl)undecane, 1,1-bis(4-hydroxyphenyl)dodecane, ... 1,1-bis(4-hydroxyphenyl)tridecane, 1,1-bis(4-hydroxyphenyl)tetradecane, 1,1-bis(4-hydroxyphenyl)pentadecane, 1,1-bis(4-hydroxyphenyl)hexadecane, 1,1-bis(4-hydroxyphenyl)heptadecane, 1,1-bis(4-hydroxyphenyl)octadecane, 1,1-bis(4-hydroxyphenyl)nonadecane, 1,1-bis(4-hydroxyphenyl)-1-phenylethane, bis(4-hydroxyphenyl)diphenylmethane, 2,2-bis(4-hydroxyphenyl)-4-methylpentane, 1,1-bis(4-hydroxyphenyl)-2-ethylhexane xane, bis(4-hydroxy-3-nitrophenyl)methane, 3,3-bis(4-hydroxyphenyl)pentane, 1,3-bis(2-(4-hydroxyphenyl)-2-propyl)benzene, 1,3-bis(2-(4-hydroxyphenyl)-2-propyl)benzene, 2,2-bis(4-hydroxyphenyl)hexafluoropropane, 1,1-bis(4-hydroxyphenyl)cyclohexane, 1,1-bis(4-hydroxyphenyl)-3-methylcyclohexane, 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane, 1,1-bis(4-hydroxyphenyl)cyclododecane,
aromatic bisaryl compounds having no fluorene skeleton, such as bis(4-hydroxyphenyl)sulfide, bis(4-hydroxy-3-methylphenyl)sulfide, bis(4-hydroxyphenyl)disulfide, 4,4'-dihydroxydiphenyl sulfoxide, bis(4-hydroxyphenyl)sulfone, 2,4'-dihydroxydiphenyl sulfone, 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxydiphenyl ketone, 4,4'-dihydroxy-3,3'-dichlorodiphenyl ether, 6,6'-dihydroxy-3,3,3',3'-tetramethyl-1,1'-spirobiindane, and 7,7'-dimethyl-6,6'-dihydroxy-3,3,3',3'-tetramethyl-1,1'-spirobiindane;
9,9-bis(4-hydroxyphenyl)fluorene, 9,9-bis(4-hydroxy-3-methylphenyl)fluorene, 9,9-bis(4-hydroxy-3-phenylphenyl)fluorene, 9,9-bis(6-hydroxy-2-naphthyl)fluorene, 9,9-bis(4-hydroxyphenyl)-1,8-diphenylfluorene, 9,9-bis(4-hydroxyphenyl)-2,7-diphenylfluorene, 9,9-bis(4-hydroxyphenyl)-3,6-diphenylfluorene, 9,9-bis(4-hydroxyphenyl)-4,5-diphenylfluorene, 9,9-bis(4-hydroxyphenyl)-1,8-di(1-naphthyl)fluorene, 9,9-bis(4-hydroxyphenyl)-2,7-di(1-naphthyl)fluorene, 9 ,9-bis(4-hydroxyphenyl)-3,6-di(1-naphthyl)fluorene, 9,9-bis(4-hydroxyphenyl)-4,5-di(1-naphthyl)fluorene, 9,9-bis(4-hydroxyphenyl)-1,8-di(2-naphthyl)fluorene, 9,9-bis(4-hydroxyphenyl)-2,7-di(2-naphthyl)fluorene, 9,9-bis(4-hydroxyphenyl)-3,6-di(2-naphthyl)fluorene, 9,9-bis(4-hydroxyphenyl)-4,5-di(2-naphthyl)fluorene, 9,9-bis(6-hydroxy-2-naphthyl)-2,7-di(2-naphthyl)fluorene, and other bisaryl compounds having a fluorene skeleton;
A compound in which the fluorene skeleton of the aforementioned bisaryl compound having a fluorene skeleton is replaced with an anthrone skeleton.

These dihydroxy compounds may be used alone or in combination of two or more.

Among the dihydroxy compounds for forming the structural unit (2) listed above, from the viewpoint of the balance of various physical properties such as the thermal stability, heat resistance, mechanical properties, and optical properties such as transparency, refractive index, and birefringence of the resin, compounds having a binaphthyl skeleton, biphenol derivatives, aromatic bisaryl compounds having no fluorene skeleton, bisaryl compounds having a fluorene skeleton, and compounds in which the fluorene skeleton is replaced with an anthrone skeleton are preferred, compounds having a binaphthyl skeleton, biphenol derivatives, and aromatic bisaryl compounds having no fluorene skeleton are more preferred, and biphenol derivatives and aromatic bisaryl compounds having no fluorene skeleton are even more preferred.

Examples of biphenol derivatives and aromatic bisaryl compounds having no fluorene skeleton for forming the structural unit (2) include:
4,4'-biphenol, 3,3'-dimethyl-4,4'-biphenol, 2,2',6,6'-tetramethylbiphenol, octamethylbiphenol, 3,3'-dichloro-4,4'-biphenol, 2,2',6,6'-tetrachlorobiphenol, octachlorobiphenol, 3,3'-dibromo-4,4'-biphenol, 2,2',6,6'-tetrabromobiphenol, octabromobiphenol, 2,2-bis(4-hydroxyphenyl)propane, 2,2-bis(3-methyl-4-hydroxyphenyl)propane, 2,2-bis(4-hydroxy-3,5-dimethylphenyl)propane, 2,2-bis(4-hydroxy-3,5-diethylphenyl)propane, 2,2-bis(4-hydroxy-(3-phenyl)phenyl)propane, 2,2-bis(4-hydroxy-(3,5-diphenyl)phenyl)propane, 1,1-bis(4-hydroxyphenyl)propane, 2,2-bis(4-hydroxy-3,5-dibromophenyl)propane, bis(4-hydroxyphenyl)methane, 1,1-bis(4-hydroxyphenyl)ethane, 1,1-bis(4-hydroxyphenyl)propane, 1,1-bis(4-hydroxyphenyl)butane, 2,2-bis(4-hydroxyphenyl)butane, 1,1-bis(4-hydroxyphenyl)pentane, 2,2-bis(4-hydroxyphenyl)pentane, 1,1-bis(4-hydroxyphenyl)hexane, 1,1-bis(4-hydroxyphenyl)heptane, 1,1-bis(4-hydroxyphenyl)octane, 1,1-bis(4-hydroxyphenyl)nonane, 1,1-bis(4-hydroxyphenyl)decane, 1,1-bis(4-hydroxyphenyl)undec ...hexane, 1,1-bis(4-hydroxyphenyl)hexane 1,1-bis(4-hydroxyphenyl)dodecane, 1,1-bis(4-hydroxyphenyl)tridecane, 1,1-bis(4-hydroxyphenyl)tetradecane, 1,1-bis(4-hydroxyphenyl)pentadecane, 1,1-bis(4-hydroxyphenyl)hexadecane, 1,1-bis(4-hydroxyphenyl)heptadecane, 1,1-bis(4-hydroxyphenyl)octadecane, 1,1-bis(4-hydroxyphenyl)nonadecane, 1,1-bis(4-hydroxyphenyl)-1-phenylethane, bis(4-hydroxyphenyl)diphenylmethane, 2,2-bis(4-hydroxyphenyl)-4-methylpentane, 1,1-bis(4-hydroxyphenyl)-2-ethylhexane, bis(4-hydroxy-3-nitrophenyl)methane, 3,3-bis(4-hydroxyphenyl)pentane, 1,3-bis(4-hydroxyphenyl)pentane, and preferably, bis(2-(4-hydroxyphenyl)-2-propyl)benzene, 1,3-bis(2-(4-hydroxyphenyl)-2-propyl)benzene, 2,2-bis(4-hydroxyphenyl)hexafluoropropane, 1,1-bis(4-hydroxyphenyl)cyclohexane, 1,1-bis(4-hydroxyphenyl)-3-methylcyclohexane, 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane, 1,1-bis(4-hydroxyphenyl)cyclododecane, bis(4-hydroxyphenyl)sulfide, bis(4-hydroxy-3-methylphenyl)sulfide, bis(4-hydroxyphenyl)disulfide, 4,4'-dihydroxydiphenylsulfoxide, bis(4-hydroxyphenyl)sulfone, and 2,4'-dihydroxydiphenylsulfone.
4,4'-biphenol, 3,3'-dimethyl-4,4'-biphenol, 2,2',6,6'-tetramethylbiphenol, octamethylbiphenol, 3,3'-dichloro-4,4'-biphenol, 2,2',6,6'-tetrachlorobiphenol, octachlorobiphenol, 3,3'-dibromo-4,4'-biphenol, 2,2',6,6'-tetrabromobiphenol, octabromobiphenol, 2,2-bis(4-hydroxyphenyl)propane, 2,2-bis(3-methyl-4-hydroxyphenyl)propane, 2,2-bis(4-hydroxy-3,5-dimethylphenyl)propane, 2,2-bis(4-hydroxy-3,5-diethylphenyl)propane , 2,2-bis(4-hydroxy-(3-phenyl)phenyl)propane, 2,2-bis(4-hydroxy-(3,5-diphenyl)phenyl)propane, 2,2-bis(4-hydroxy-3,5-dibromophenyl)propane, bis(4-hydroxyphenyl)methane, 1,1-bis(4-hydroxyphenyl)ethane, 1,1-bis(4-hydroxyphenyl)propane, 1,1-bis(4-hydroxyphenyl)butane, 2,2-bis(4-hydroxyphenyl)butane, 1,1-bis(4-hydroxyphenyl)pentane, 2,2-bis(4-hydroxyphenyl)pentane, 1,1-bis(4-hydroxyphenyl)hexane, 1,1-bis(4-hydroxyphenyl)hexane, 1,1-bis(4-hydroxyphenyl)heptane, 1,1-bis(4-hydroxyphenyl)octane, 1,1-bis(4-hydroxyphenyl)nonane, 1,1-bis(4-hydroxyphenyl)decane, 1,1-bis(4-hydroxyphenyl)undecane, 1,1-bis(4-hydroxyphenyl)-1-phenylethane, bis(4-hydroxyphenyl)diphenylmethane, 2,2-bis(4-hydroxyphenyl)-4-methylpentane, 1,1-bis(4-hydroxyphenyl)-2-ethylhexane, bis(4-hydroxy-3-nitrophenyl)methane, 3,3-bis(4-hydroxyphenyl)pentane, 1,3-bis(2-(4-hydroxyphenyl)-2-propyl)benzene, 1,3 bis(2-(4-hydroxyphenyl)-2-propyl)benzene, 2,2-bis(4-hydroxyphenyl)hexafluoropropane, 1,1-bis(4-hydroxyphenyl)cyclohexane, 1,1-bis(4-hydroxyphenyl)-3-methylcyclohexane, 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane, bis(4-hydroxyphenyl)sulfide, bis(4-hydroxy-3-methylphenyl)sulfide, bis(4-hydroxyphenyl)disulfide, 4,4'-dihydroxydiphenylsulfoxide, bis(4-hydroxyphenyl)sulfone, and 2,4'-dihydroxydiphenylsulfone are more preferred.
4,4'-biphenol, 3,3'-dimethyl-4,4'-biphenol, 2,2',6,6'-tetramethylbiphenol, octamethylbiphenol, 2,2-bis(4-hydroxyphenyl)propane, 2,2-bis(3-methyl-4-hydroxyphenyl)propane, 2,2-bis(4-hydroxy-3,5-dimethylphenyl)propane, 2,2-bis(4-hydroxy-3,5-diethylphenyl)propane, 2,2-bis(4-hydroxy-(3-phenyl)phenyl)propane, 2,2-bis(4-hydroxy-(3,5-diphenyl)phenyl)propane, )phenyl)propane, bis(4-hydroxyphenyl)methane, 1,1-bis(4-hydroxyphenyl)ethane, 1,1-bis(4-hydroxyphenyl)-1-phenylethane, bis(4-hydroxyphenyl)diphenylmethane, bis(4-hydroxyphenyl)sulfide, bis(4-hydroxy-3-methylphenyl)sulfide, bis(4-hydroxyphenyl)disulfide, 4,4'-dihydroxydiphenylsulfoxide, bis(4-hydroxyphenyl)sulfone, and 2,4'-dihydroxydiphenylsulfone are more preferred,
Particularly preferred are 4,4'-biphenol (hereinafter abbreviated as BP), 2,2-bis(4-hydroxyphenyl)propane (hereinafter abbreviated as BPA), 1,1-bis(4-hydroxyphenyl)-1-phenylethane (hereinafter abbreviated as BisAP), bis(4-hydroxyphenyl)diphenylmethane (hereinafter abbreviated as BisBP), and bis(4-hydroxyphenyl)sulfide (hereinafter abbreviated as BPS).

If 50 mol% or more of the dihydroxy compound used as the raw material for structural unit (2) is selected from BP, BPA, BisAP, BisBP, and BPS, the dihydroxy compound is easy to use from the standpoint of both safety and cost, and the resulting resin has a good balance of various physical properties such as thermal stability, heat resistance, mechanical properties, and optical properties. Among these, BP, BisAP, BisBP, and BPS are more preferable because the refractive index of the resin is high, BPA and BisAP are preferable because the birefringence of the resin is small, and BP, BPA, and BisAP are preferable because the coloring of the resin is small.

<Other structural units>
The resin of the present invention may contain structural units other than the structural unit (1) and the structural unit (2) (hereinafter, these may be referred to as "other structural units"), and examples of monomers that form the other structural units in the resin include aliphatic dihydroxy compounds, alicyclic dihydroxy compounds, dihydroxy compounds containing a condensed ring structure, dihydroxy compounds containing an acetal ring, oxyalkylene glycols, dihydroxy compounds containing an aromatic component, diester compounds, etc. Among these, dihydroxy compounds containing an aromatic component are preferred from the viewpoint of increasing the reaction efficiency.

(Aliphatic dihydroxy compounds)
As the aliphatic dihydroxy compound, for example, the following dihydroxy compounds can be used.
Dihydroxy compounds of straight-chain aliphatic hydrocarbons such as ethylene glycol, 1,3-propanediol, 1,2-propanediol, 1,4-butanediol, 1,3-butanediol, 1,2-butanediol, 1,5-heptanediol, 1,6-hexanediol, 1,9-nonanediol, 1,10-decanediol, and 1,12-dodecanediol; dihydroxy compounds of branched aliphatic hydrocarbons such as neopentyl glycol and hexylene glycol.

(Alicyclic dihydroxy compounds)
As the alicyclic dihydroxy compound, for example, the following dihydroxy compounds can be used.
dihydroxy compounds which are primary alcohols of alicyclic hydrocarbons, exemplified by dihydroxy compounds derived from terpene compounds such as 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, tricyclodecane dimethanol, pentacyclopentadecane dimethanol, 2,6-decalin dimethanol, 1,5-decalin dimethanol, 2,3-decalin dimethanol, 2,3-norbornane dimethanol, 2,5-norbornane dimethanol, 1,3-adamantanedimethanol, and limonene;
Dihydroxy compounds which are secondary and tertiary alcohols of alicyclic hydrocarbons, such as 1,2-cyclohexanediol, 1,4-cyclohexanediol, 1,3-adamantanediol, hydrogenated bisphenol A, and 2,2,4,4-tetramethyl-1,3-cyclobutanediol.

(Dihydroxy Compounds Containing a Fused Ring Structure)
As the dihydroxy compound containing a condensed ring structure, for example, a dihydroxy compound represented by the following formula (IA), exemplified by isosorbide (ISB), isomannide, isoidet, etc., can be used.

(Dihydroxy Compounds Containing Acetal Rings)
As the dihydroxy compound containing an acetal ring, for example, a spiro glycol represented by the following formula (IB), a dioxane glycol represented by the following formula (IC), or a dihydroxy compound derived from inositol represented by the following formula (ID) can be used.

(In the above formula (ID), R ²⁰ and R ²¹ each independently represent an organic group having 1 to 30 carbon atoms. These organic groups may have any substituent.)

In the formula (ID), R ²⁰ and R ²¹ are preferably an organic group having 1 to 30 carbon atoms which may have a substituent. Examples of the organic group having 1 to 30 carbon atoms which may have a substituent of R ²⁰ and R ²¹ include alkyl groups such as methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, and dodecyl group, cycloalkyl groups such as cyclopentyl group and cyclohexyl group, linear or branched chain alkenyl groups such as vinyl group, propenyl group, and hexenyl group, cyclic alkenyl groups such as cyclopentenyl group and cyclohexenyl group, alkynyl groups such as ethynyl group, methylethynyl group, and 1-propionyl group, aryl groups such as phenyl group, naphthyl group, and toluyl group, alkoxyphenyl groups such as methoxyphenyl group, aralkyl groups such as benzyl group and phenylethyl group, and heterocyclic groups such as thienyl group, pyridyl group, and furyl group. Among these, from the viewpoint of the stability of the resin, alkyl groups, cycloalkyl groups, aryl groups, aralkyl groups, etc. are preferred, and from the viewpoint of the balance between the optical properties, weather resistance, heat resistance, and mechanical properties of the resin, alkyl groups and cycloalkyl groups are particularly preferred.

(Oxyalkylene glycols)
As the oxyalkylene glycol, for example, the following dihydroxy compounds can be used.
Diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, polypropylene glycol.

(Dihydroxy Compounds Containing Aromatic Components)
As the dihydroxy compound containing an aromatic component, for example, the following dihydroxy compounds can be used.
2,2-bis(4-(2-hydroxyethoxy)phenyl)propane, 2,2-bis(4-(2-hydroxypropoxy)phenyl)propane, 1,3-bis(2-hydroxyethoxy)benzene, 4,4'-bis(2-hydroxyethoxy)biphenyl, bis(4-(2-hydroxyethoxy)phenyl)sulfone, 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy)-3-phenylphenyl)fluorene, 9,9-bis(2-(2-hydroxyethoxy)naphthyl)fluorene, 2,2'-bis(2-hydroxyethoxy)-3,3'-dimethyl-1,1'-biphenyl Dihydroxy compounds having an ether group bonded to an aromatic group, such as naphthalene, 2,2'-bis(2-hydroxyethoxy)-6,6'-dimethyl-1,1'-binaphthalene, 2,2'-bis(2-hydroxyethoxy)-7,7'-dimethyl-1,1'-binaphthalene, 2,2'-bis(2-hydroxyethoxy)-1,1'-binaphthalene, 2,2'-bis(2-hydroxyethoxy)-3,3'-diphenyl-1,1'-binaphthalene, 2,2'-bis(2-hydroxyethoxy)-6,6'-diphenyl-1,1'-binaphthalene, and 2,2'-bis(2-hydroxyethoxy)-7,7'-diphenyl-1,1'-binaphthalene:

As dihydroxy compounds containing aromatic components that form other structural units, 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene and 2,2'-bis(2-hydroxyethoxy)-1,1'-binaphthalene are preferred in terms of the balance between optical properties, thermal properties, and raw material costs.

(Diester Compound)
As the diester compound, for example, the following dicarboxylic acids can be used.
Aromatic dicarboxylic acids such as terephthalic acid, phthalic acid, isophthalic acid, 4,4'-diphenyldicarboxylic acid, 4,4'-diphenyletherdicarboxylic acid, 4,4'-benzophenonedicarboxylic acid, 4,4'-diphenoxyethanedicarboxylic acid, 4,4'-diphenylsulfonedicarboxylic acid, and 2,6-naphthalenedicarboxylic acid;
Alicyclic dicarboxylic acids such as 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, and decalin-2,6-dicarboxylic acid; aliphatic dicarboxylic acids such as malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, and sebacic acid;
These dicarboxylic acid components can be used as raw materials for polyester carbonate as dicarboxylic acid itself, but depending on the production method, dicarboxylic acid esters such as methyl esters and phenyl esters, and dicarboxylic acid derivatives such as dicarboxylic acid halides can also be used as raw materials. Since the polymerization reactivity of diester compounds is relatively low, from the viewpoint of increasing the reaction efficiency, it is preferable to use less other diester compounds, excluding carbonate esters and diester compounds having an oligofluorene structure unit.

The dihydroxy compounds and diester compounds for forming the other structural units may be used alone or in combination of two or more types depending on the required performance of the resulting resin.

From the viewpoint of more reliably obtaining the effects of the present invention by containing the structural units (1) and (2), the resin of the present invention, including cases in which other structural units are contained, preferably contains the structural units (1) and (2) in the above-mentioned suitable contents so that the total content of the structural units (1) and (2) in 100% by weight of the resin is 80% by weight or more, particularly 90% by weight or more, and furthermore 95 to 100% by weight.
Thus, in the resin of the present invention, it is preferable that the content of other structural units is small, and if the content is high, the thermal stability of the resin may be reduced.

<Carbonate diester>
The carbonate bond, which is a linking group contained in the polycarbonate resin or polyester carbonate resin, which is a preferred embodiment of the resin of the present invention, is introduced by polymerizing a carbonate diester represented by the following formula (4).

(In formula (4), ^A3 and ^A4 each represent an aliphatic hydrocarbon group having 1 to 18 carbon atoms which may have a substituent, or an aromatic hydrocarbon group which may have a substituent, and ^A3 and ^A4 may be the same or different.)

^A3 and ^A4 are preferably substituted or unsubstituted aromatic hydrocarbon groups, more preferably unsubstituted aromatic hydrocarbon groups. Examples of the substituents of the aliphatic hydrocarbon groups include ester groups, ether groups, carboxylic acids, amide groups, and halogens, and examples of the substituents of the aromatic hydrocarbon groups include alkyl groups such as methyl groups and ethyl groups.

Examples of the carbonic acid diester represented by the formula (4) include diphenyl carbonate (hereinafter sometimes abbreviated as DPC), substituted diphenyl carbonate such as ditolyl carbonate, and dialkyl carbonate such as dimethyl carbonate, diethyl carbonate, and di-tert-butyl carbonate, with diphenyl carbonate and substituted diphenyl carbonate being preferred, and diphenyl carbonate being particularly preferred.

Carbonate diesters may contain impurities such as chloride ions, which may inhibit the polymerization reaction or deteriorate the hue of the resulting resin, so it is preferable to use distilled or other purified products as necessary.

In addition, when a polymerization reaction is carried out using both the diester compound represented by the formula (11) and the carbonic acid diester represented by the formula (4), if A ¹ and A ² in the formula (4) and A ³ and A ⁴ in the formula (4) all have the same structure, the components eliminated during the polymerization reaction are the same, and the components can be easily recovered and reused. From the viewpoint of polymerization reactivity and usefulness in reuse, it is particularly preferable that A ¹ to A ⁴ are phenyl groups. Note that when A ¹ to A ⁴ are phenyl groups, the component eliminated during the polymerization reaction is phenol.

When the resin of the present invention has a carbonate structural unit derived from a carbonate diester represented by formula (4), the content of the carbonate structural unit in 100% by weight of the resin of the present invention is preferably 20% by weight or less, particularly 11% by weight or less, and especially 6% by weight or less, from the viewpoint of improving the refractive index of the resin and reducing birefringence while ensuring the necessary amounts of structural unit (1) and structural unit (2). On the other hand, from the viewpoint of improving the thermal stability of the resin, the content of the carbonate structural unit is preferably 0.1% by weight or more, particularly 0.7% by weight or more, and especially 2.0% by weight or more.

<Characteristics of resin>
The resin of the present invention contains the structural unit (2) in an appropriate ratio, which brings about the effects of improving thermal stability and reducing birefringence, and contains the structural unit (1), which brings about the effects of improving melt fluidity and reducing birefringence of a molded article while maintaining high heat resistance and a high refractive index.

The reduced viscosity (η _sp /C) of the resin of the present invention is preferably 0.15 to 1.20, more preferably 0.17 to 0.72, and even more preferably 0.20 to 0.60. If the reduced viscosity is equal to or higher than the lower limit, the resin has good thermal stability, heat resistance, and mechanical strength, and if it is equal to or lower than the upper limit, the resin has a low melt viscosity, is excellent in injection moldability, and the molded article has low birefringence.

The reduced viscosity of the resin is measured using the method described in the Examples section below.

The refractive index ( _nD ) of the resin of the present invention at a wavelength of 589 nm and a temperature of 20°C is preferably 1.59 or more, more preferably 1.60 to 1.70, and even more preferably 1.61 to 1.66. If the refractive index is 1.59 or more, the added value of the resin is high when used as an optical member such as a lens. In order to obtain a resin with a refractive index of more than 1.70, it is necessary to excessively increase the content of aromatic rings or the content of S element in the resin of the present invention, and there is a risk that the Tg of the resin will be excessively high, the thermal stability of the resin will be reduced, or mold contamination will be increased.

The Abbe number (ν _D ) of the resin of the present invention at a temperature of 20° C. is preferably 35.0 or less, more preferably 11.0 or more and 32.0 or less, and even more preferably 16.0 or more and 27.0 or less. If the Abbe number is small, the resin is useful as a material for aberration-correcting low Abbe number concave lens used in combination with a high Abbe number convex lens such as COP (cycloolefin polymer).

The refractive index is rounded off to the fourth decimal place, and the Abbe number is rounded off to the first decimal place. The refractive index and Abbe number of the resin are measured by the method described in the Examples section below.

The resin of the present invention preferably has an in-plane orientation birefringence of −0.0010 or more and 0.0020 or less at a wavelength of 550 nm when produced from the resin in a stretched film.
If the orientation birefringence of the stretched film is -0.0010 or more, the birefringence of the molded article made of the resin is reduced. On the other hand, if the orientation birefringence of the stretched film is 0.0020 or less, the birefringence of the molded article made of the resin is reduced. The orientation birefringence is more preferably -0.0010 or more and 0.0010 or less, and even more preferably -0.0004 or more and 0.0004 or less.

The in-plane orientation birefringence of the stretched film at a wavelength of 550 nm is measured by the method described in the Examples section below.

The resin of the present invention has a high glass transition temperature (Tg) and is excellent in heat resistance. The Tg of the resin of the present invention is preferably 110° C. or higher, more preferably 120° C. or higher, and even more preferably 130° C. or higher.
On the other hand, from the viewpoint of ensuring good moldability, the Tg of the resin of the present invention is preferably 250° C. or lower, more preferably 230° C. or lower, and even more preferably 200° C. or lower.
The glass transition temperature of the resin of the present invention can be easily adjusted to a range that allows both high heat resistance and good moldability by appropriately selecting the structure and content of the structural unit (2) at will, and therefore the resin of the present invention is suitable for applications that are expected to be exposed to high temperature environments, such as in-vehicle optical lenses.

The glass transition temperature (Tg) of the resin is measured by the method described in the Examples section below.

The 1% thermal weight loss temperature (Td) of the resin of the present invention under nitrogen is preferably 355°C or higher, more preferably 356°C or higher, and even more preferably 363°C or higher. The higher the 1% thermal weight loss temperature, the higher the thermal stability and the higher the resistance to use at high temperatures. In addition, the manufacturing temperature can be increased and the control range during manufacturing can be wider, making manufacturing easier. On the other hand, the lower the 1% thermal weight loss temperature under nitrogen, the lower the thermal stability and the more difficult it is to use at high temperatures. In addition, the control range during manufacturing becomes narrower, making manufacturing more difficult. There is no particular limit to the upper limit of the 1% thermal weight loss temperature under nitrogen.

The 1% thermal weight loss temperature (Td) of the resin under nitrogen is measured using the method described in the Examples section below.

[Method of producing resin]
The polyester resin and polyester carbonate resin of the present invention can be produced by a commonly used polymerization method. For example, they can be produced by a solution polymerization method or an interfacial polymerization method using phosgene or a carboxylic acid halide, or a melt polymerization method in which a reaction is carried out without using a solvent. Among these production methods, it is preferable to produce them by the melt polymerization method, which does not use a solvent or a highly toxic compound, thereby reducing the environmental load and is also excellent in productivity.

When a solvent is used in polymerization, the solvent may remain in the resin, and the plasticizing effect of the solvent may lower the glass transition temperature of the resin, which may cause quality fluctuations in processing steps such as molding and stretching, which will be described later. Furthermore, halogenated organic solvents such as methylene chloride are often used as solvents, but if halogenated solvents remain in the resin, they may cause corrosion of metal parts when molded products using this resin are incorporated into electronic devices, etc. Resins obtained by melt polymerization do not contain solvents, which is also advantageous for stabilizing processing steps and product quality.

When producing resin by melt polymerization, a monomer having the structural units described above, a carbonic acid diester, and a polymerization catalyst are mixed and subjected to an ester exchange reaction (also called a polycondensation reaction) under molten conditions, and the reaction rate is increased while removing elimination components from the system. At the end of the polymerization, the reaction is allowed to proceed under high temperature and high vacuum conditions until the desired molecular weight is reached. Once the reaction is complete, the molten resin is removed from the reactor, and the resin of the present invention is obtained.

In the polycondensation reaction, the reaction rate and the molecular weight of the resulting resin can be controlled by strictly adjusting the molar ratio of all dihydroxy compounds and all diester compounds used in the reaction. The molar ratio of the total amount of carbonate diester and all diester compounds to all dihydroxy compounds is preferably adjusted to 0.90 to 1.30, more preferably 0.96 to 1.20, and particularly preferably 0.98 to 1.10.

If the molar ratio deviates significantly above or below the range, it becomes impossible to produce a resin with the desired molecular weight. If the molar ratio is too small, the number of hydroxyl group terminals in the produced resin increases, which may deteriorate the thermal stability of the resin. Furthermore, a large amount of unreacted dihydroxy compounds remains in the resin, which may cause dirt on the molding machine and poor appearance of the molded product in the subsequent molding process. On the other hand, if the molar ratio is too large, the rate of the transesterification reaction may decrease under the same conditions, or the amount of remaining carbonate diesters and diester compounds in the produced resin may increase, and these remaining low molecular weight components may similarly cause problems in the molding process.

The melt polymerization method is usually carried out in a multi-stage process of two or more stages. The polycondensation reaction may be carried out in two or more stages using one polymerization reactor with sequentially changing conditions, or in two or more stages using two or more reactors with different conditions for each stage, but from the viewpoint of production efficiency, it is carried out using two or more, preferably three or more, reactors. The polycondensation reaction may be performed in a batch system, a continuous system, or a combination of a batch system and a continuous system, but from the viewpoint of production efficiency and quality stability, a continuous system is preferred.

In the polycondensation reaction, it is important to properly control the balance between temperature and pressure in the reaction system. If either the temperature or pressure is changed too quickly, there is a risk that unreacted monomers will be distilled out of the reaction system. As a result, the molar ratio of the dihydroxy compound and the diester compound will change, and a resin with the desired molecular weight may not be obtained.
In addition, the polymerization rate of the polycondensation reaction is controlled by the balance between the hydroxyl group terminal and the ester group terminal or carbonate group terminal. Therefore, particularly when polymerization is performed in a continuous manner, if the balance of the terminal groups fluctuates due to the distillation of unreacted monomers, it becomes difficult to control the polymerization rate at a constant rate, and the molecular weight of the resulting resin may fluctuate greatly. Since the molecular weight of a resin correlates with the melt viscosity, when the resulting resin is molded, the melt viscosity may fluctuate, leading to problems such as failure to obtain molded products of uniform dimensions.

Furthermore, if unreacted monomers are distilled off, not only the balance of the terminal groups will be affected, but the copolymerization composition of the resin will deviate from the desired composition, which may affect the mechanical properties and optical properties. Since the optical properties of the resin of the present invention, such as the birefringence and refractive index, are controlled by the ratio of structural unit (1) to structural unit (2) in the resin, if this ratio is lost during the polycondensation reaction, the designed optical properties may not be obtained.

Hereinafter, the melt polycondensation reaction process will be described separately into a stage in which a monomer is consumed to produce an oligomer, and a stage in which polymerization is allowed to proceed up to a desired molecular weight to produce a polymer.
Specifically, the following conditions can be adopted as the reaction conditions in the first stage reaction. That is, the internal temperature of the polymerization reactor is set in the range of usually 100° C. or more, preferably 150° C. or more, more preferably 170° C. or more, and usually 250° C. or less, preferably 240° C. or less, more preferably 230° C. or less. The pressure of the polymerization reactor is set in the range of usually 70 kPa or less (hereinafter, pressure refers to absolute pressure), preferably 50 kPa or less, more preferably 30 kPa or less, and usually 1 kPa or more, preferably 3 kPa or more, more preferably 5 kPa or more. The reaction time is set in the range of usually 0.1 hours or more, preferably 0.5 hours or more, and usually 10 hours or less, preferably 5 hours or less, more preferably 3 hours or less.

The first-stage reaction is carried out while the monohydroxy compound derived from the diester compound generated is distilled out of the reaction system. For example, when diphenyl carbonate is used as the carbonic acid diester, the monohydroxy compound distilled out of the reaction system in the first-stage reaction is phenol.
In the first stage reaction, the lower the reaction pressure, the more the polymerization reaction can be accelerated, but on the other hand, the more unreacted monomers are distilled off. In order to simultaneously suppress the distillation of unreacted monomers and accelerate the reaction by reducing the pressure, it is effective to use a reactor equipped with a reflux condenser. It is particularly good to use a reflux condenser in the early stages of the reaction when there is a lot of unreacted monomers.

In the second stage reaction, the pressure of the reaction system is gradually lowered from the pressure of the first stage, and the monohydroxy compound generated is removed from the reaction system, and the pressure of the reaction system is finally set to 5 kPa or less, preferably 3 kPa or less, more preferably 1 kPa or less. The internal temperature is usually set to 210°C or more, preferably 220°C or more, and usually 300°C or less, preferably 290°C or less, more preferably 260°C or less. The reaction time is usually set to 0.1 hours or more, preferably 0.5 hours or more, more preferably 1 hour or more, and usually 10 hours or less, preferably 5 hours or less, more preferably 3 hours or less. In order to suppress coloration and thermal deterioration and obtain a resin with good hue and thermal stability, the maximum internal temperature in all reaction stages is set to 270°C or less, preferably 265°C or less, and more preferably 260°C or less.

The transesterification catalyst (hereinafter sometimes simply referred to as catalyst or polymerization catalyst) that can be used during polymerization can have a very large effect on the reaction rate and the color tone and thermal stability of the resin obtained by polycondensation. The catalyst used is not limited as long as it satisfies the transparency, hue, heat resistance, thermal stability, and mechanical strength of the produced resin, but examples of the catalyst include metal compounds of Group 1 or Group 2 of the long-form periodic table (hereinafter simply referred to as "Group 1" and "Group 2"), basic boron compounds, basic phosphorus compounds, basic ammonium compounds, and basic compounds such as amine compounds. Preferably, at least one metal compound selected from the group consisting of metals of Group 2 of the long-form periodic table, lithium, and cesium is used.

As the Group 1 metal compound, for example, the following compounds can be used, but other Group 1 metal compounds can also be used: sodium hydroxide, potassium hydroxide, lithium hydroxide, cesium hydroxide, sodium hydrogen carbonate, potassium hydrogen carbonate, lithium hydrogen carbonate, cesium hydrogen carbonate, sodium carbonate, potassium carbonate, lithium carbonate, cesium carbonate, sodium acetate, potassium acetate, lithium acetate, cesium acetate, sodium stearate, potassium stearate, lithium stearate, cesium stearate, sodium borohydride, potassium borohydride, lithium borohydride, cesium borohydride, sodium tetraphenylborate, tetraphenylborate potassium tetraphenylborate, lithium tetraphenylborate, cesium tetraphenylborate, sodium benzoate, potassium benzoate, lithium benzoate, cesium benzoate, disodium hydrogen phosphate, dipotassium hydrogen phosphate, dilithium hydrogen phosphate, dicesium hydrogen phosphate, disodium phenylphosphate, dipotassium phenylphosphate, dilithium phenylphosphate, dicesium phenylphosphate, sodium, potassium, lithium, cesium alcoholate, phenolate, disodium salt, dipotassium salt, dilithium salt, dicesium salt of bisphenol A. Of these, it is preferable to use lithium compounds and cesium compounds from the viewpoint of polymerization activity and the hue of the obtained resin.

As the Group 2 metal compound, for example, the following compounds can be used, but other Group 2 metal compounds can also be used. Calcium hydroxide, barium hydroxide, magnesium hydroxide, strontium hydroxide, calcium hydrogen carbonate, barium hydrogen carbonate, magnesium hydrogen carbonate, strontium hydrogen carbonate, calcium carbonate, barium carbonate, magnesium carbonate, strontium carbonate, calcium acetate, barium acetate, magnesium acetate, strontium acetate, calcium stearate, barium stearate, magnesium stearate, strontium stearate. Of these, magnesium compounds, calcium compounds, and barium compounds are preferably used, and from the viewpoint of polymerization activity and the hue of the obtained resin, magnesium compounds and/or calcium compounds are more preferably used, and calcium compounds are most preferably used.

It is also possible to use, in combination with the Group 1 metal compound and/or Group 2 metal compound, a basic compound such as a basic boron compound, a basic phosphorus compound, a basic ammonium compound, or an amine compound as an auxiliary, but it is particularly preferable to use at least one metal compound selected from the group consisting of metals in Group 2 of the long form periodic table, lithium, and cesium.
The amount of the polymerization catalyst used is usually 0.1 μmol to 300 μmol, preferably 0.5 μmol to 200 μmol per mol of the total dihydroxy compounds used in the polymerization. When at least one metal compound selected from the group consisting of metals of Group 2 of the long periodic table, lithium, and cesium is used as the polymerization catalyst, particularly when a magnesium compound and/or a calcium compound and/or a cesium compound is used, the amount of the polymerization catalyst used is usually 0.1 μmol or more, preferably 0.3 μmol or more, and particularly preferably 0.5 μmol or more, per mol of the total dihydroxy compounds. The amount of the polymerization catalyst used is preferably 200 μmol or less, preferably 100 μmol or less, and particularly preferably 50 μmol or less.

When a polyester resin or polyester carbonate resin is produced using a diester compound as a monomer, an ester exchange catalyst such as a titanium compound, a tin compound, a germanium compound, an antimony compound, a zirconium compound, a lead compound, an osmium compound, a zinc compound, or a manganese compound can be used, either in combination with or without the basic compound. The amount of these ester exchange catalysts used is usually within the range of 1 μmol to 1 mmol, preferably 5 μmol to 800 μmol, and particularly preferably 10 μmol to 500 μmol, in terms of the metal amount, per mol of the total dihydroxy compounds used in the reaction.

If the amount of catalyst is too small, the polymerization rate will be slow, and the polymerization temperature will have to be increased accordingly to obtain a resin with the desired molecular weight. This will increase the likelihood that the hue of the resulting resin will deteriorate, and unreacted raw materials will volatilize during the polymerization, disrupting the molar ratio of dihydroxy compounds and diester compounds, and the desired molecular weight may not be achieved. On the other hand, if too much polymerization catalyst is used, undesirable side reactions may occur, causing a deterioration in the hue of the resulting resin and discoloration or decomposition of the resin during molding.

Among the Group 1 metals, sodium and potassium can adversely affect the color if contained in large amounts in the resin. These metals can be mixed in not only from the catalyst used, but also from the raw materials and reaction equipment. Regardless of the source, the total amount of compounds of these metals in the resin should be 2 μmol or less, preferably 1 μmol or less, and more preferably 0.5 μmol or less, per 1 mol of the total dihydroxy compounds.

After the resin of the present invention is polymerized as described above, it can usually be cooled and solidified, and pelletized with a rotary cutter or the like. The pelletization method is not limited, but examples include a method in which the resin is withdrawn in a molten state from the final polymerization reactor, cooled and solidified in the form of strands, and pelletized; a method in which the resin is supplied in a molten state from the final polymerization reactor to a single-screw or twin-screw extruder, melt-extruded, cooled and solidified, and pelletized; and a method in which the resin is withdrawn in a molten state from the final polymerization reactor, cooled and solidified in the form of strands, pelletized once, and then supplied to a single-screw or twin-screw extruder again, melt-extruded, cooled and solidified, and pelletized.

Since the resin of the present invention is suitable for optical applications, it is preferable that the resin contains little foreign matter. In order to remove foreign matter such as scorch and gel from the resin obtained by melt polycondensation, it is preferable to perform filtration using a filter. In particular, it is preferable to remove residual monomers and by-product phenols by devolatilization under reduced pressure, and to mix additives such as heat stabilizers and mold release agents by melt extruding the resin using the vented twin-screw extruder described above, and then filtering it using a filter.

The filter may be of any known shape, such as a candle type, pleat type, or leaf disk type. The aperture of the filter is preferably 50 μm or less, more preferably 40 μm or less, and even more preferably 20 μm or less, in terms of 99% filtration accuracy. If it is particularly desired to reduce foreign matter, the aperture of the filter is preferably 10 μm or less, but if the aperture is small, the pressure loss in the filter increases, which may lead to damage to the filter or deterioration of the resin due to shear heat, so it is preferable that the aperture be 1 μm or more in terms of 99% filtration accuracy. The aperture of the filter referred to here is determined in accordance with ISO 16889.

The resin filtered through the filter is discharged from the die head in the form of strands, cooled and solidified, and pelletized with a rotary cutter or the like. When the resin is stranded or pelletized in direct contact with the outside air, it is preferable to use a JIS B
It is preferable to carry out the experiment in a clean room with a cleanliness level of Class 7, or more preferably Class 6, as defined in IEC 602609-2002.

When pelletizing, it is preferable to use cooling methods such as air cooling or water cooling. When cooling with air, it is preferable to use air that has been previously cleaned of foreign matter in the air using a HEPA filter or the like to prevent the re-adhesion of foreign matter in the air. When using water cooling, it is preferable to use water that has been cleaned of metals in the water using an ion exchange resin or the like, and that has had foreign matter removed from the water using a water filter. The mesh size of the water filter used is preferably 10 to 0.45 μm, which provides a filtration accuracy of 99% removal.

The resin of the present invention is at least one resin selected from the group consisting of polyester carbonates and polyesters, containing a structural unit represented by formula (1) and a structural unit represented by formula (2), and containing 40% by weight or more of the structural unit represented by the following formula (2) when the total weight of the resin is taken as 100% by weight. The above-mentioned structural units (1) and (2) may not all be contained in the same polymer molecule. In other words, as long as the above-mentioned structural units are contained in a specific amount in the entirety of multiple polymer molecules, the resin of the present invention may be a blend resin composed of two or more types of resins. For example, the resin containing both the above-mentioned structural units (1) and (2) may be one or more copolymers containing both the structural units (1) and (2), or may be a mixture of one or more homopolymers or copolymers containing the structural unit (1) and one or more homopolymers or copolymers containing the structural unit (2).

[Resin composition]
The resin composition of the present invention is a mixture of the resin of the present invention with known additives and/or resins other than the resin of the present invention (hereinafter sometimes referred to as "other resins").

As the additive, any known additive can be used without particular restriction as long as it does not impair the excellent physical properties of the resin of the present invention. Examples of the additive include the various additives exemplified as additives that may be contained in the molded product of the present invention described below, and particularly, at least one selected from the group consisting of heat stabilizers, antioxidants, ultraviolet absorbers, brightness enhancers, dyes, pigments, mold release agents, flow modifiers, and impact resistance improvers.

Furthermore, the resin composition of the present invention may contain other resins as long as the excellent physical properties of the resin of the present invention are not impaired.
Other resins include thermoplastic polyester resins such as polycarbonate resin, polyester resin, polyester carbonate resin, polyethylene terephthalate resin, polytrimethylene terephthalate, and polybutylene terephthalate resin; styrene-based resins such as polystyrene resin, high impact polystyrene resin (HIPS), acrylonitrile-styrene copolymer (AS resin), acrylonitrile-styrene-acrylic rubber copolymer (ASA resin), and acrylonitrile-ethylene propylene rubber-styrene copolymer (AES resin); polyolefin resins such as polyethylene resin and polypropylene resin; polyamide resin; polyimide resin; polyetherimide resin; polyurethane resin; polyphenylene ether resin; polyphenylene sulfide resin; polysulfone resin; and polymethacrylate resin.

The other resins may be contained in one type or in any combination and ratio of two or more types.

[Molded body]
The molded article of the present invention can be produced by molding a material containing the resin of the present invention or the resin composition of the present invention.

The shape of the molded product of the present invention is not particularly limited, and examples include one-dimensional structures (e.g., linear, thread-like, etc.), two-dimensional structures (e.g., film-like, sheet-like, plate-like, etc.), and three-dimensional structures (e.g., concave or convex lens-like, rod-like, hollow (tubular), etc.).

The molded article of the present invention may contain various additives [for example, fillers or reinforcing agents, colorants (for example, dyes and pigments), conductive agents, flame retardants, plasticizers, lubricants, stabilizers (for example, antioxidants, ultraviolet absorbers, heat stabilizers), release agents, antistatic agents, dispersants, flow control agents, leveling agents, defoamers, surface modifiers, stress reducing agents (for example, silicone oils, silicone rubbers, various plastic powders, various engineering plastic powders, etc.), carbon materials, etc.]. These additives may be used alone or in combination of two or more.

The molded article of the present invention can be manufactured using, for example, injection molding, injection compression molding, extrusion molding, transfer molding, blow molding, pressure molding, casting molding, etc.

When the molded article of the present invention is produced by such a molding method, the maximum temperature during molding is preferably 400°C or less, more preferably 380°C or less, and even more preferably 360°C or less. If the molded article is molded at a temperature exceeding the above upper limit, air bubbles or coloring may occur in the molded article obtained. The maximum temperature during molding is preferably 240°C or more, more preferably 250°C or more, and even more preferably 260°C or more. At temperatures below the above lower limit, the fluidity during molding is low and filling into the mold may be insufficient. The resin of the present invention has high thermal stability and an orientation birefringence close to zero, so that a molded article with low birefringence can be obtained over a wide range of molding temperatures.

The molded article of the present invention has excellent heat resistance and optical properties (high refractive index, low birefringence, etc.), and can be used as optical components such as optical films, optical lenses, and optical sheets.

In particular, the resin of the present invention is suitable for injection molding, like conventional polycarbonate lenses in which BPA is a polymerization component, and polycarbonate lenses in which BPEF is a polymerization component, and is therefore useful for forming optical lenses. Optical lenses include, but are not limited to, in-vehicle lenses, eyeglass lenses, pickup lenses, camera lenses, microarray lenses, projector lenses, and Fresnel lenses. In particular, the resin of the present invention has high heat resistance, and can therefore be suitably used in applications in which use in high-temperature environments is expected, such as in-vehicle optical lenses.

The present invention will be described in more detail below with reference to synthesis examples and examples, but the present invention is not limited to the following examples.

The physical properties of the resins produced in the following examples and comparative examples were evaluated using the following methods.

(1) Compositional Ratio of Structural Units in Resin The compositional ratio of structural units in a resin was calculated from the compositional ratio of each monomer charged during the production of the resin.
Alternatively, the composition ratio can be calculated by measuring ^1H -NMR of the resin dissolved in deuterated chloroform. Specifically, a deuterated chloroform solution of the resin is prepared so that the resin concentration is 30 mg/mL, and measurement is performed at 30°C, with a relaxation time of 5 seconds and an accumulated number of 128 times.
As an alternative method, the composition ratio can be calculated by subjecting the resin to hydrolysis and measuring the resulting reaction solution by liquid chromatography. The specific method is as follows.
Dissolve 0.5 g of resin in 5 mL of dichloromethane. Add 45 mL of methanol and then 5 mL of 25% aqueous sodium hydroxide solution. Heat and reflux at 75°C for 30 minutes while stirring. After cooling, add 7 mL of 17.5% hydrochloric acid, then adjust to 100 mL with methanol and pure water. Measure the adjusted solution using a high performance liquid chromatograph equipped with an analytical column and a detector.

(2) Reduced Viscosity A resin sample was dissolved in methylene chloride to prepare a resin solution with a precise concentration of 0.6 g/dL. Using a Ubbelohde viscometer manufactured by Moritomo Rika Kogyo Co., Ltd., measurements were performed at a temperature of 20.0°C ± 0.1°C to measure the solvent passage time _t0 and the solution passage time t. The relative viscosity η _rel was calculated by the following formula (i) using the obtained _t0 and t values, and the specific viscosity η _sp was calculated by the following formula (ii) using the obtained relative viscosity η _rel .
η _rel =t/t ₀ (i)
η _sp = (η−η ₀ )/η ₀ =η _rel −1 (ii)
Thereafter, the obtained specific viscosity η _sp was divided by the concentration c [g/dL] to obtain the reduced viscosity η _sp /c.

(3) Glass transition temperature (Tg)
Using a differential scanning calorimeter DSC6220 manufactured by SII Nanotechnology, about 10 mg of the resin sample was heated at a heating rate of 20°C/min to measure the calorific value, and the extrapolated glass transition onset temperature was determined according to JIS K7121, which is the temperature at the intersection of a straight line extending the low-temperature side baseline to the high-temperature side and a tangent drawn at the point where the gradient of the curve of the stepwise change in the glass transition is maximum. The extrapolated glass transition temperature was designated as the glass transition temperature (Tg).

(4) 1 % thermogravimetric reduction temperature (Td)
Using a TG/DTA7200 manufactured by SII Nanotechnology, approximately 10 mg of a resin sample was placed in a container, and measurements were taken from 30°C to 500°C at a heating rate of 10°C/min under a nitrogen atmosphere (nitrogen flow rate 200 ml/min). The temperature (Td) at which the weight decreased by 1% was determined.

(5) Film Forming Approximately 5 g of a resin sample that had been vacuum-dried at 100° C. for 2 hours or more was pressed in a heat press machine using a spacer having a width of 150 mm, a length of 150 mm, and a thickness of 0.1 mm at a heat press temperature of 200 to 260° C., preheated for 1 to 3 minutes, and pressurized at a pressure of 20 MPa for 1 minute, and then removed together with the spacer and cooled at room temperature to produce a film with a thickness of 100 μm.

(6) Refractive index (n _D ), Abbe number (ν _D )
A rectangular test piece 40 mm long and 8 mm wide was cut out from the film prepared by the method of (5) to be used as a measurement sample. The refractive indexes nC, nD, and nF at each wavelength were measured using a multi-wavelength Abbe refractometer (DRM4/1550 manufactured by Atago Co., Ltd.) and interference filters with wavelengths of 656 nm ( _C line), 589 nm ( _D line), and 486 nm ( _F line). The measurement was performed at 20°C using monobromonaphthalene or a sulfur methylene iodide solution as the interface liquid.
The Abbe number _νD was calculated by the following formula (iii).
ν _D = (1-n _D )/(n _C -n _F ) (iii)

(7) Preparation of Stretched Film A film piece having a length of 100 mm and a width of 70 mm was cut out from the film prepared by the method of (5).
The free end of the film piece was uniaxially stretched using a stretching machine under conditions of a stretching speed of 300%/min, a stretching ratio of 1.5 times, and a stretching temperature of the glass transition temperature of the resin + 15°C to produce a stretched film.

(8) Measurement of orientation birefringence (Δn) of stretched film The central part of the stretched film produced by the method of (7) was cut into a length of 40 mm and a width of 40 mm, and the phase difference was measured at a measurement wavelength of 550 nm using a phase difference measuring device KOBRA-WPR manufactured by Oji Scientific Instruments Co., Ltd. The orientation birefringence Δn was calculated from the phase difference R550 at a wavelength of 550 nm and the film thickness of the stretched film according to the following formula (iv). When the slow axis direction coincides with the stretching direction, Δn is shown as a positive value, and when the slow axis direction coincides with a direction perpendicular to the stretching direction, Δn is shown as a negative value.
Δn=R550 [nm]/(film thickness [mm]×10 ⁶ ) (iv)

(9) Molding of Injection Molded Plates Using a small injection molding machine (Shinko Selvic C, Mobile Co., Ltd.), the temperature conditions were adjusted to the range of cylinder temperature: temperatures shown in Tables 1 to 3 (Tg+105 to 155° C.), and mold temperature: 110 to 150° C., to mold dumbbell-shaped resin plates having a total length of 75 mm, a parallel portion length of 30 mm, a parallel portion width of 5 mm, a thickness of 2 mm, and a gripping portion width of 10 mm.

(10) Birefringence of injection-molded plate The injection-molded plate prepared by the method in (9) was used as a test piece, and was sandwiched between two polarizers in a cross-Nicol state at the angle at which the polarized color appears strongest, and placed on an observation table. Under the condition that white light was irradiated from behind, the polarized color appearing on the test piece was visually observed, and the degree of birefringence was evaluated according to the following criteria.
◎: No polarized color is seen, or polarized color is seen only in the 5 mm-wide parallel portion, resulting in one color. ○: Polarized color is seen only in the 5 mm-wide parallel portion, resulting in two colors. △: Polarized color is seen only in the 5 mm-wide parallel portion, resulting in three or more colors. ×: Polarized color is seen over the entire test piece.

[Synthesis Example 1: Bis[9-(2-phenoxycarbonylethyl)fluoren-9-yl]
Synthesis of methane (hereinafter abbreviated as "2Q")]
According to the method described in JP 2015-25111 A, 2Q represented by the following formula (11A) was synthesized.

[Synthesis Example 2: Synthesis of 1,1-bis(4-hydroxyphenyl)dodecane (hereinafter abbreviated as "BP12A")]
BP12A was synthesized by the method described in Example 1 of JP2019-085399A.

The abbreviations of the compounds used in the following Examples and Comparative Examples are as follows.
BisAP: 1,1-bis(4-hydroxyphenyl)-1-phenylethane (Tokyo Chemical Industry Co., Ltd.)
BisBP: bis(4-hydroxyphenyl)diphenylmethane (Tokyo Chemical Industry Co., Ltd.)
BPS: Bis(4-hydroxyphenyl)sulfone (Tokyo Chemical Industry Co., Ltd.)
BP: 4,4'-biphenol (Tokyo Chemical Industry Co., Ltd.)
BP12A: 1,1-bis(4-hydroxyphenyl)dodecane BPA: 2,2-bis(4-hydroxyphenyl)propane (manufactured by Mitsubishi Chemical Corporation)
BPEF: 9,9-bis[4-(2-hydroxyethoxy)phenyl]fluorene (Osaka Gas Chemicals Co., Ltd.)
BNEF: 9,9-bis[6-(2-hydroxyethoxy)-2-naphthyl]fluorene (manufactured by Osaka Gas Chemicals Co., Ltd.)
DPC: Diphenyl carbonate (manufactured by Mitsubishi Chemical Corporation)
2Q: bis[9-(2-phenoxycarbonylethyl)fluoren-9-yl]methane PTSB: catalyst deactivator, butyl paratoluenesulfonate (Tokyo Chemical Industry Co., Ltd.)
Adeka STAB 2112: Antioxidant, Adeka STAB 2112 (manufactured by ADEKA CORPORATION)
Irg1076: Antioxidant, Irganox 1076 (manufactured by BASF)

[Example 1]
A raw material mixture was prepared by adding 100.0 mol % BisAP, 60.0 mol % DPC, 40.0 mol % 2Q, and a 0.4 mass % aqueous solution of cesium carbonate as a catalyst to a glass reactor equipped with a reactor agitator, a reactor heating device ^, and a reactor pressure adjusting device, when the total amount of all dihydroxy compounds as raw materials was 100 mol %.

Next, the pressure inside the glass reactor was reduced to about 50 Pa (0.38 Torr), and then the operation of returning the pressure to atmospheric pressure with nitrogen was repeated three times to replace the inside of the reactor with nitrogen. After replacing with nitrogen, the temperature outside the reactor was set to 220°C, and the temperature inside the reactor was gradually raised to dissolve the mixture. Then, the stirrer was rotated at 100 rpm. Then, while distilling off the phenol by-produced by the oligomerization reaction of the dihydroxy compounds DPC and 2Q that takes place inside the reactor, the pressure inside the reactor was reduced from 101.3 kPa (760 Torr) to 13.3 kPa (100 Torr) in absolute pressure over 40 minutes.

Then, the pressure inside the reactor was kept at 13.3 kPa, and the transesterification reaction was carried out for 80 minutes while further distilling off the phenol. After that, the temperature outside the reactor was raised to 250°C, and the pressure inside the reactor was reduced from 13.3 kPa (100 Torr) to 399 Pa (3 Torr) absolute pressure over 40 minutes, and the distilled phenol was removed from the system. Furthermore, as the final temperature, the temperature outside the reactor was raised to 260°C, and the absolute pressure inside the reactor was reduced to 30 Pa (approximately 0.2 Torr), and the polycondensation reaction was carried out. The polycondensation reaction was terminated when the reactor agitator reached a predetermined stirring power.

Next, the pressure inside the reactor was restored to 101.3 kPa absolute pressure with nitrogen, and then the gauge pressure was increased to 0.2 MPa. The polyester carbonate resin was extracted in the form of strands from the bottom of the reactor. After the strands of resin were obtained, a rotary cutter was used to obtain pellets of the polyester carbonate resin.
The polyester carbonate resin was subjected to the above-mentioned procedures for evaluation, and the results are shown in Table 1.

[Examples 2 to 6]
A polyester carbonate resin was obtained in the same manner as in Example 1, except that the raw materials and conditions for melt polymerization were as shown in Table 1. The polyester carbonate resin was evaluated according to the above-mentioned procedures. The results are shown in Table 1.

[Comparative Example 1]
A polyester resin was obtained in the same manner as in Example 1, except that the raw materials and conditions for melt polymerization were as shown in Table 1. The polyester resin was subjected to various evaluations according to the above procedures. The results are shown in Table 1.

[Comparative Example 2]
A polycarbonate resin was obtained in the same manner as in Example 1, except that the raw materials and conditions for melt polymerization were as shown in Table 1. The polycarbonate resin was subjected to various evaluations according to the procedures described above. The results are shown in Table 1.

[Comparative Example 3]
A polyester carbonate resin was obtained in the same manner as in Example 1, except that the raw materials and conditions for melt polymerization were as shown in Table 1, and the temperature outside the reactor in the step of dissolving the mixture in the reaction vessel was 230° C. This polyester carbonate resin was subjected to various evaluations according to the procedures described above. The results are shown in Table 1.

[Examples 7 and 8]
For the resin obtained in Example 1, a plate was produced by the method of (9) above under the conditions of a cylinder temperature and a mold temperature of 150° C. shown in Table 2, and birefringence was evaluated by the method of (10) above. The results are shown in Table 2 together with the results of Example 1.

[Example 9]
The same resin as in Example 1 and additive components PTSB, ADK STAB 2112, and Irg1076 were blended and mixed in the ratios (parts by mass) shown in Table 3 below, and then fed to a Japan Steel Works (TEX30HSS) equipped with one vent, and kneaded under the conditions of a screw rotation speed of 160 rpm, a discharge rate of 15 kg/h, and a barrel temperature of 260 ° C. The kneaded product was extruded into a strand-like molten resin, which was quenched in a water tank and pelletized using a pelletizer to obtain pellets of a polyester carbonate resin composition. For this polyester carbonate resin composition, a plate was prepared by the method (9) above under the conditions of a cylinder temperature and a mold temperature of 150 ° C. shown in Table 3, and birefringence was evaluated by the method (10) above. The results are shown in Table 3 together with the results of Example 1.

[Discussion of evaluation results]
The polyester carbonate resins of Examples 1 to 6 had small absolute values of orientation birefringence, and the birefringence of the molded bodies was small. Furthermore, because Td was high, it was possible to melt process it at a wider range of temperatures, which is advantageous for injection molding. Therefore, it is excellent as a material for molded bodies, particularly molded bodies for optical components. In addition, because the refractive index _nD was high, it was suitable for use in applications requiring thinning, such as optical lenses. And because Tg was high, it was suitable for use in applications requiring heat resistance.

As shown in Examples 7 and 8, the polyester carbonate resin of the present invention can be injection molded under a wide range of temperature conditions and has excellent moldability. Furthermore, regardless of the injection molding conditions, the birefringence of the molded product is always low and the optical properties are excellent.

As shown in Example 9, the polyester carbonate resin of the present invention can be kneaded with additive components to form a polyester carbonate resin composition. The polyester carbonate resin composition of the present invention can be injection molded, and the molded article has low birefringence.

On the other hand, the resin of Comparative Example 1 has relatively high Td and Tg, but because the composition ratio of structural units derived from aromatic dihydroxy compounds in which the hydroxy group represented by formula (2) is directly bonded to an aromatic group is low, the orientation birefringence of the stretched film is negatively large and the birefringence of the molded product is large.

The resins of Comparative Examples 2 and 3 have small birefringence in the molded body, but because they do not contain structural unit (2), they have low Td and poor thermal stability. For this reason, the temperature range in which they can be melt-processed and the usable temperature range of the molded body may be narrow, making them inferior as molding materials.

From the above, the resin of the present invention has a higher Td than the resin of the comparative example, and can be melt-processed and molded at a wide range of temperatures, making it an excellent molding material. Furthermore, since it has a high refractive index and the birefringence of the molded product is small, it is excellent as a molding material for optical components. Furthermore, it can be designed to have a high Tg, making it an excellent material for optical components that require heat resistance.

The resin of the present invention has high thermal stability, a small absolute value of orientation birefringence, low birefringence of a molded article, and a high refractive index and high heat resistance.
Therefore, the resin of the present invention and a resin composition containing the same can be easily processed into optical components by a method such as injection molding.
These optical members are excellent in that they have a high refractive index and low birefringence while maintaining high thermal stability and high heat resistance.

Examples of such optical members include optical lenses, optical films, optical sheets, etc. Examples of optical lenses include vehicle-mounted lenses, eyeglass lenses, pickup lenses, camera lenses, microarray lenses, projector lenses, Fresnel lenses, etc.
The resin of the present invention has high thermal stability and high heat resistance, and by appropriately selecting an aromatic dihydroxy compound, it has particularly high heat resistance, so that it can be suitably used as a material for optical components that are expected to be used in high-temperature environments, such as vehicle-mounted lenses.

Claims (18)

A polyester carbonate resin containing a structural unit represented by the following formula (1) and a structural unit represented by the following formula (2):
A resin containing 40% by weight or more of a structural unit represented by the following formula (2), when the total weight of the resin is taken as 100% by weight.

(In formula (1), R ¹¹ to R ¹² are each independently an alkylene group having 2 to 3 carbon atoms; R ¹³ is a direct bond or an alkylene group having 1 to 4 carbon atoms which may have a substituent; and R ¹⁴ to R ¹⁹ are each independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms which may have a substituent, an aryl group having 6 to 10 carbon atoms which may have a substituent, an acyl group having 1 to 10 carbon atoms which may have a substituent, an amino group which may have a substituent, an alkenyl group having 2 to 10 carbon atoms which may have a substituent, an alkynyl group having 2 to 10 carbon atoms which may have a substituent, an oxygen atom which has a substituent, a sulfur atom which has a substituent, a silicon atom which has a substituent, a halogen atom, a nitro group, or a cyano group; provided that at least two adjacent groups among R ¹⁴ to R ¹⁹ may be bonded to each other to form a ring.)

(In formula (2), Ar ¹ represents an unsubstituted or substituted aromatic hydrocarbon group having 6 to 88 carbon atoms, or a divalent group having 6 to 88 carbon atoms to which an unsubstituted or substituted aromatic hydrocarbon ring is linked via a direct bond or any linking group, and each of the two oxygen atoms shown in formula (2) represents that it is directly bonded to the same or different aromatic hydrocarbon ring in Ar ^1. ) The resin according to claim 1, wherein the content of the structural unit represented by formula (1) is 5% by weight or more when the total weight of the resin is 100% by weight. The resin according to claim 1 or 2, wherein the total content of the structural unit represented by formula (1) and the structural unit represented by formula (2) is 80% by weight or more when the total weight of the resin is 100% by weight. The resin according to any one of claims 1 to 3, wherein the formula (2) is represented by the following formula (3):

(In formula (3), rings Z ¹ and Z ² each independently represent an aromatic hydrocarbon ring. ^{R 1} and R ² each independently represent an unsubstituted or substituted alkyl group having 1 to 10 carbon atoms, an unsubstituted or substituted aromatic hydrocarbon group having 6 to 10 carbon atoms, an unsubstituted or substituted acyl group having 1 to 10 carbon atoms, an oxygen atom having a substituent, a sulfur atom having a substituent, a silicon atom having a substituent, or a halogen atom. a and b each independently represent an integer of 0 or more. When a and b are 2 or more and there are multiple R ^1s and multiple R ^2s , the multiple R ^1s and R ^2s may be the same as or different from each other. At least two of the multiple R ^1s and/or R ^2s may be bonded to each other to form a ring. Y represents a single bond, a hydrocarbon group having 1 to 44 carbon atoms which may contain an aromatic group, O, S, S-S, SO, SO ₂ , or CO group.) The resin according to claim ₄ , wherein, in the formula (3), Y is a single bond, a hydrocarbon group having 1 to 44 carbon atoms which may contain an aromatic group, S, S-S, SO, or SO2. The resin according to claim 5, wherein in the formula (3), Y is a single bond, S, S-S, SO, _SO2 , or a group represented by any one of the following formulas (Y1) to (Y3) (wherein the * marks in the following formulas (Y1) to (Y3) indicate bonding sites with the rings ^Z1 and ^Z2 in the formula (3)).

(In formula (Y1), R ³ and R ⁴ each independently represent a hydrogen atom or an unsubstituted or substituted alkyl group having 1 to 10 carbon atoms.)

(In formula (Y2), R ⁵ is a hydrogen atom or an unsubstituted or substituted alkyl group having 1 to 10 carbon atoms. R ⁶ is an unsubstituted or substituted aromatic hydrocarbon group having 1 to 10 carbon atoms, an unsubstituted or substituted aromatic hydrocarbon group having 6 to 10 carbon atoms, an unsubstituted or substituted acyl group having 1 to 10 carbon atoms, or a halogen atom. c represents an integer of 0 to 5. When c is 2 or more and there are multiple R ^6s , the multiple R ^6s may be the same or different. In addition, at least two groups among the multiple R ^6s may be bonded to each other to form a ring.)

(In formula (Y3), R ⁷ and R ⁸ each independently represent an unsubstituted or substituted alkyl group having 1 to 10 carbon atoms, an unsubstituted or substituted aromatic hydrocarbon group having 6 to 10 carbon atoms, an unsubstituted or substituted acyl group having 1 to 10 carbon atoms, or a halogen atom. d and e each independently represent an integer of 0 to 5. When d and e are 2 or more and there are a plurality of R ^7s and R ^8s , the plurality of R ^7s and R ^8s may be the same or different. Furthermore, at least two of the plurality of R ^7s and/or R ^8s may be bonded to each other to form a ring.) The resin according to claim 6, wherein the formula (3) is at least one selected from the group consisting of the following formulas (3-1) to (3-5):

(In formulas (3-1) to (3-5), R ¹ , R ² , a, and b are defined the same as in formula (3). In formula (3-4), R ⁶ and c are defined the same as in formula (Y2). In formula (3-5), R ⁷ , R ⁸ , d, and e are defined the same as in formula (Y 3 ).) The resin according to claim 7, wherein the formula (3) is at least one selected from the group consisting of the following formulas (3-6) to (3-10):

The resin according to any one of claims 1 to 8, which has a refractive index of 1.59 or more at a wavelength of 589 nm. The resin according to any one of claims 1 to 9, having an Abbe number νD of 35.0 or less. The resin according to any one of claims 1 to 10, wherein the in-plane orientation birefringence at a wavelength of 550 nm of a stretched film made from the resin is -0.0010 or more and 0.0020 or less. The resin according to any one of claims 1 to 11, having a 1% thermal weight loss temperature (Td) under nitrogen of 355°C or higher. The resin according to any one of claims 1 to 12, having a glass transition temperature (Tg) of 110°C or more and 250°C or less. A resin composition comprising the resin according to any one of claims 1 to 13 and at least one additive selected from the group consisting of a heat stabilizer, an antioxidant, an ultraviolet absorber, a brightness enhancer, a dye, a pigment, a release agent, a flow modifier, and an impact resistance improver. A resin composition comprising the resin according to any one of claims 1 to 13 or the resin composition according to claim 14, further comprising another resin. A molded article obtained by molding the resin according to any one of claims 1 to 13 or the resin composition according to claims 14 or 15. The molded body according to claim 16, wherein the molded body is an optical component. The molded article according to claim 17, wherein the optical member is at least one optical lens selected from the group consisting of an in-vehicle lens, a spectacle lens, a pickup lens, a camera lens, a microarray lens, a projector lens, and a Fresnel lens.