JP2010168707A - Ordinary pressure cation-dyeable polyester multifilament - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an atmospheric pressure cation-dyeable polyester multifilament which uses a recycled polymer prepared by depolymerizing polyester wastes to a raw material monomer and then repolymerizing the monomer, can be dyed with cationic dyes at the atmospheric pressure, and has a highly water-absorbing-quick dryable property. <P>SOLUTION: This atmospheric pressure cation-dyeable polyester multifilament is characterized by using a polyester prepared by depolymerizing polyester wastes into a raw material monomer and then repolymerizing the monomer, comprising a metal sulfoisophthalate (A) and a specific compound (B) in the acid component under a condition simultaneously satisfying specific numerical expressions, and has a projection coefficient of 0.3-0.7, and 3-6 fin portions outward projected from a core portion of a filament cross section, in the cross section of the monofilament. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention is a highly atypical product comprising a normal pressure cationic dyeable polyester that is dyeable to a cationic dye under normal pressure, using a recycled polymer that is depolymerized to raw material monomers and then re-polymerized. The present invention relates to an atmospheric pressure cationic dyeable polyester multifiber having a fiber cross section.

  Polyester is widely used as a fabric material for clothing by taking advantage of its excellent properties. Along with the diversification, upgrading, and individualization of clothing life, attempts are being made to impart the desirable performance of natural fibers, such as water absorption, to polyester fibers. Furthermore, in sports apparel applications such as running shirts and golf shirts, fabrics that have quick-drying properties in addition to water-absorbing performance have been used to maintain a comfortable state even when sweating. Realization of water absorption and quick drying performance is also desired for fibers. As a method for imparting water absorption and quick drying performance to polyester fibers, a method for obtaining a highly water-absorbing and quick-drying material by making the cross section of the fiber atypical has been proposed (see, for example, Patent Document 1).

  However, polyester fibers represented by polyethylene terephthalate have the disadvantage that a clear and deep hue is difficult to obtain because they can be dyed only with disperse dyes and azoic dyes because of their chemical properties. As a method for eliminating such drawbacks, a method in which a metal salt of sulfoisophthalic acid is copolymerized with 2 to 3 mol% of polyester has been proposed (see, for example, Patent Documents 2 and 3).

  However, the polyester fiber obtained by such a method can be dyed only under high temperature and high pressure, and if it is dyed after knitting or weaving with natural fiber or urethane fiber, natural fiber and urethane fiber are embrittled. There was a problem. If this is to be sufficiently dyed at normal pressure and at a temperature around 100 ° C., it is necessary to copolymerize a large amount of the metal salt of sulfoisophthalic acid. In this case, from the thickening effect due to the sulfonate group, There is a problem that the degree of polymerization of the polyester cannot be increased, the strength of the polyester fiber obtained by melt spinning is remarkably lowered, and the spinning operability is remarkably deteriorated.

  On the other hand, in order to solve such a problem, a technique for copolymerizing a cationic dyeable monomer having a small ion-binding intermolecular force has been disclosed (for example, see Patent Documents 4 and 5). Examples of cationic dyeable monomers having a small ion-binding intermolecular force include 5-sulfoisophthalic acid tetrabutoxyphosphonate and the like, but these cationic dyeable monomer copolyesters have poor thermal stability, and are not limited to atmospheric pressure cations. Even if an attempt was made to increase the amount of copolymerization for dyeing, thermal decomposition progressed during the polymerization reaction, making it difficult to increase the molecular weight. Furthermore, there is a drawback that the decomposition due to the thermal history during melt spinning is large, and the strength of the resulting yarn is weakened. Further, the 5-sulfoisophthalic acid tetrabutoxyphosphonate used is very expensive, and there is a problem that the cost of the resulting cationic dyeable polyester is greatly increased.

As a method for solving such a problem, in addition to a metal salt of sulfoisophthalic acid, a method of copolymerizing polyethylene glycol having a molecular weight of 2000 or more, a method of copolymerizing a dicarboxylic acid of a linear hydrocarbon such as adipic acid or sebacic acid, Alternatively, a method of copolymerizing glycol components such as diethylene glycol, neopentyl glycol, and cyclohexanedimethanol has been proposed. (For example, see Patent Documents 6 and 7)
However, the strength of the atmospheric pressure cationic dyeable polyester fiber obtained by melt spinning the polyester obtained by any of these methods is lowered, and thus the tear strength of the resulting fabric is lowered, and further the dyeing fastness is increased. There was a problem such as low.

  Further, there has been proposed a composite fiber in which a polyester copolymerized with 5-sodium sulfoisophthalic acid is disposed in a sheath portion and a polyester having 95 mol% or more of ethylene terephthalate repeating units disposed in a core portion (see, for example, Patent Document 8). ). However, the copolymerization amount of the sulfoisophthalic acid component in the copolyester constituting the sheath part is limited for the same reason as described above, and it is difficult to obtain sufficient dyeing properties. As a result, there are problems such as an increase in processing cost in the spinning process or a restriction on the fiber cross-sectional shape.

On the other hand, interest in the degree of influence of polyester products on the global environment has increased, and for example, fibers using recycled polymers have been desired.
However, recycled polymers, commonly referred to as polyester waste, are known to be material recycling, in which recovered PET bottles and polyester film products, as well as scrap polymers generated in the manufacturing process of these products, are crushed and remelted. However, it is difficult to obtain a recycled fiber with high strength, fineness and good texture without fluff, and the above-mentioned apparel that is thin, light and high in strength is difficult. In particular, when spinning an atypical fiber, yarn breakage frequently occurs, and the productivity is remarkably lowered, making commercial production difficult.

JP 2003-166119 A Japanese Patent Publication No.34-10497 JP-A-62-89725 JP-A-1-162822 JP 2006-176628 A JP 2002-284863 A JP 2006-200064 A Japanese Patent Laid-Open No. 7-126920

  The present invention solves the above-mentioned problems, and can use a recycled polymer obtained by depolymerizing polyester waste to a raw material monomer and then re-polymerizing it, enabling cationic dyeing under normal pressure, and high water absorption and quick drying. The present invention provides an atmospheric pressure cationic dyeable polyester multi-fiber.

In view of the above problems, the present inventors have intensively studied, and as a result, have completed the present invention.
That is, according to the present invention,
Atmospheric pressure cationic dyeable polyester multi-fiber, characterized by satisfying the following requirements,
a) Recycled dimethyl terephthalate obtained by depolymerizing polyalkylene terephthalate as an ester-forming derivative of an aromatic dicarboxylic acid is used as the polyester, and the dimethyl terephthalate is an ester-forming property of wholly aromatic dicarboxylic acid. It consists of polyester which occupies 80 mol% or more of derivatives.
b) In the acid component constituting the polyester, the metal salt of sulfoisophthalic acid (A) and the compound (B) represented by the following chemical formula (1) are converted into the following formula (1) and formula (2) simultaneously. It must be a copolyester contained under satisfactory conditions.
c) The diethylene glycol content in the polyester is 2.5% by weight or less and the intrinsic viscosity is in the range of 0.55 to 1.0.
d) In the cross section orthogonal to the single fiber axis, the protrusion coefficient defined by the following formula is 0.3 to 0.7, and there are 3 to 6 fin portions protruding outward from the fiber cross section core portion. = (A1-b1) / a1
a1: Length from the center of the inscribed circle of the inner wall of the fiber cross section to the top of the fin part b1: Radius of the inscribed circle of the inner wall of the fiber cross section

［上記式中、Ｒは水素または炭素数１〜１０のアルキル基を表し、Ｘは４級ホスホニウム塩、または４級アンモニウム塩を表す。］
３．０≦Ａ＋Ｂ≦５．０ （数式：１）
０．２≦Ｂ／（Ａ＋Ｂ）≦０．７ （数式：２）
［ここで、Ａはスルホイソフタル酸の金属塩の共重合量（モル％）、Ｂは上記化学式（１）で表される化合物の共重合量（モル％）を表す。］
が提供される。

[In the above formula, R represents hydrogen or an alkyl group having 1 to 10 carbon atoms, and X represents a quaternary phosphonium salt or a quaternary ammonium salt. ]
3.0 ≦ A + B ≦ 5.0 (Formula: 1)
0.2 ≦ B / (A + B) ≦ 0.7 (Formula: 2)
[Here, A represents the copolymerization amount (mol%) of the metal salt of sulfoisophthalic acid, and B represents the copolymerization amount (mol%) of the compound represented by the chemical formula (1). ]
Is provided.

  Polyethylene terephthalate using the recycled dimethyl terephthalate of the present invention for the transesterification reaction reduces the burden on the environment, has good dyeing property by cationic dyeing under normal pressure, and has high water absorption and quick drying properties. High-strength polyester fibers similar to those obtained when virgin PET is used are obtained.

The schematic diagram which showed 1 embodiment of the polyester multi fiber cross section of this invention. The schematic diagram which showed one embodiment of the spinneret discharge hole used by this invention.

Hereinafter, the present invention will be described in detail.
The polyester used in the normal pressure cationic dyeable polyester multifilament of the present invention is a recycled polyester described below, and a metal salt of sulfoisophthalic acid (A) as a copolymerization component and the following general formula (1) It is necessary that the compound (B) is a copolyester containing the following formula 1 and formula 2 simultaneously.

  Cationic dyeable polyester multi having a single yarn fineness of 7 dtex or less, a bundle of 24 or more single yarns, a strength of 2.0 cN / dtex or more, an elongation of 60% or less, and a hot water shrinkage of 22% or less. A filament is preferred.

［上記式中、Ｒは水素または炭素数１〜１０のアルキル基を表し、Ｘは４級ホスホニウム塩、または４級アンモニウム塩を表す。］
３．０≦Ａ＋Ｂ≦５．０ 数式１
０．２≦Ｂ／（Ａ＋Ｂ）≦０．７ 数式２
［ここで、Ａはスルホイソフタル酸の金属塩の共重合量（モル％）、Ｂは上記一般式（１）で表される化合物の共重合量（モル％）を表す。］

[In the above formula, R represents hydrogen or an alkyl group having 1 to 10 carbon atoms, and X represents a quaternary phosphonium salt or a quaternary ammonium salt. ]
3.0 ≦ A + B ≦ 5.0 Formula 1
0.2 ≦ B / (A + B) ≦ 0.7 Formula 2
Here, A represents the copolymerization amount (mol%) of the metal salt of sulfoisophthalic acid, and B represents the copolymerization amount (mol%) of the compound represented by the general formula (1). ]

The polyester multi-fiber of the present invention has 3 to 6 fin portions protruding outward from the fiber cross-section core portion having a projection coefficient of 0.3 to 0.7 defined by the following formula in the single fiber cross section (for example, FIG. 1). It is an atypical cross-section fiber characterized in that there are individual fibers.
Projection coefficient = (a1-b1) / a1
a1: Length from the center of the inscribed circle of the inner wall of the fiber cross section to the top of the fin part b1: Radius of the inscribed circle of the inner wall of the fiber cross section

(Description of recycled polyester)
The polyester used in the polyester multifilament of the present invention is dimethyl terephthalate obtained by depolymerizing polyalkylene terephthalate as an ester-forming derivative of an aromatic dicarboxylic acid, based on the total acid components constituting the polyester. It is necessary to use more than% by weight.

  Here, polyethylene terephthalate is preferable as the polyalkylene terephthalate, and particularly recovered bottles, recovered polyester fiber products, recovered polyester film products, and waste polymers generated in the manufacturing process of these products were recovered. Polyester is preferably used.

  When the amount of dimethyl terephthalate obtained by depolymerizing polyalkylene terephthalate is less than 70% by weight, it is derived from the finally obtained polyester or components contained in the polyester fiber, from the recovered dimethyl terephthalate. Since the component ratio is less than 50%, the effect as an environmentally friendly product is reduced, which is not preferable. The dimethyl terephthalate obtained by depolymerizing the polyalkylene terephthalate is preferably 80% by weight or more, more preferably 90% by weight or more.

  The method for producing dimethyl terephthalate obtained by depolymerizing polyalkylene terephthalate is not particularly limited. For example, polyethylene terephthalate is depolymerized with ethylene glycol, and then transesterified with methanol. Examples thereof include a method of refining dimethyl acid by recrystallization or distillation.

  As for impurities in dimethyl terephthalate obtained by depolymerizing polyalkylene terephthalate used in the present invention, the content of 2-hydroxyterephthalic acid is preferably 2 ppm or less.

  As a method for producing a polyester using 80% by weight or more based on the total acid components constituting dimethyl terephthalate obtained by depolymerizing polyalkylene terephthalate, the above-mentioned terephthalic acid can be used as an ester-forming derivative of an aromatic dicarboxylic acid. Preference is given to producing dimethyl by transesterification with ethylene glycol as alkylene glycol in the presence of a transesterification catalyst.

(Description of component A)
Examples of the sulfonate group-containing aromatic dicarboxylic acid component used in the present invention include a metal salt of 5-sulfoisophthalic acid (sodium salt, lithium salt, potassium salt), a quaternary phosphonium salt of 5-sulfoisophthalic acid, or 5 -Quaternary ammonium salts of sulfoisophthalic acid are exemplified. These ester-forming derivatives are also preferably exemplified. Among these groups, a metal salt of 5-sulfoisophthalic acid is preferably exemplified from the viewpoint of thermal stability, cost, etc., and in particular, a sodium salt of 5-sulfoisophthalic acid and a dimethyl ester thereof, 5-sulfoisophthalic acid. Particularly preferred is the sodium salt of dimethyl acid.

(Description of component B)
The compound (B) represented by the chemical formula (1) is quaternary phosphonium salt or quaternary ammonium salt of 5-sulfoisophthalic acid or its lower alkyl ester. As the quaternary phosphonium salt, the quaternary ammonium salt is preferably a quaternary phosphonium salt or a quaternary ammonium salt substituted with an alkyl group, a benzyl group or a phenyl group, and particularly preferably a quaternary phosphonium salt. The four substituents may be the same or different. Specific examples of the compound represented by the chemical formula (1) include 5-sulfoisophthalic acid tetrabutylphosphonium salt, 5-sulfoisophthalic acid ethyltributylphosphonium salt, 5-sulfoisophthalic acid benzyltributylphosphonium salt, and 5-sulfoisophthalic acid. Acid phenyltributylphosphonium salt, 5-sulfoisophthalic acid tetraphenylphosphonium salt, 5-sulfoisophthalic acid butyltriphenylphosphonium salt, 5-sulfoisophthalic acid benzyltriphenylphosphonium salt, or dimethyl ester or diethyl ester of these isophthalic acid derivatives Preferably exemplified.

(Explanation of Formula 1)
In the present invention, the total of component A and component B copolymerized with the polyester needs to be within a range of A + B of 3.0 to 5.0 mol% based on the acid component. If it is less than 3.0 mol%, sufficient dyeing cannot be obtained by cationic dyeing under normal pressure. On the other hand, if it exceeds 5.0 mol%, the strength of the resulting polyester yarn is lowered, which is not suitable for practical use. Further, since the dye is consumed excessively, it is disadvantageous in terms of cost.

(Explanation of Formula 2)
The component ratio between component A and component B must be such that B / (A + B) is in the range of 0.2 to 0.7. When the ratio is 0.2 or less, that is, in a state where the proportion of component A is large, it is difficult to increase the degree of polymerization of the resulting polyester due to the thickening effect of the metal salt of sulfoisophthalic acid. On the other hand, when the ratio is 0.7 or more, that is, the ratio of the component B is large, the reaction is slow, and when the ratio of the component B is further increased, the decomposition proceeds and the degree of polymerization cannot be increased. Further, when the ratio of component B is increased, the thermal stability is deteriorated, and the decrease in molecular weight due to thermal decomposition when remelted in the melt spinning stage is increased, so that the strength of the resulting polyester yarn is decreased, which is not preferable.

(Description of DEG amount)
The diethylene glycol contained in the normal pressure cationic dyeable polyester in the present invention is preferably 2.5% by weight or less.
In general, when a cationic dyeable polyester is produced, in order to suppress the amount of diethylene glycol (DEG) by-produced in the production process of the polyester, a small amount of alkali metal salt, alkaline earth metal salt, hydroxide is used as a DEG inhibitor. 1 to 20 mol of the cationic dyeable monomer (compounds (A) and (B) in the case of the present invention) at least one of tetraalkylphosphonium, tetraalkylammonium hydroxide, trialkylamine and the like used. It is preferable to add about%.

(Explanation of intrinsic viscosity)
The intrinsic viscosity (solvent: orthochlorophenol, measurement temperature: 35 ° C.) of the polyester used in the present invention is preferably in the range of 0.55 to 1.0. When the intrinsic viscosity is 0.55 or less, the strength of the resulting polyester fiber is insufficient. On the other hand, when it is 1.0 or more, the melt viscosity becomes too high and melt molding becomes difficult. Since the production cost in the polycondensation step of the polymerized polyester is greatly increased by the solid phase polymerization method subsequent to the melt polymerization method, it is not preferable. The intrinsic viscosity of the normal pressure cationic dyeable polyester is more preferably in the range of 0.60 to 0.90.

(Method for producing copolymer polyester)
The production of the copolyester in the present invention is not particularly limited, and a conventionally known polyester production method is used. That is, a low polymer is produced by transesterification of recycled dimethyl terephthalate and ethylene glycol. Next, this reactive organism is produced by adding compound A and compound B in the presence of a polycondensation catalyst, heating under reduced pressure, and subjecting the reaction product to a polycondensation reaction until a predetermined polymerization degree is reached.

(Other additives)
In addition, the copolymer polyester in the present invention contains a small amount of additives as necessary, for example, antioxidants, fluorescent whitening agents, antistatic agents, antibacterial agents, ultraviolet absorbers, light stabilizers, heat stabilizers, and light-shielding agents. Or it may contain a matting agent. In particular, antioxidants and matting agents are particularly preferably added.

(Yarn making method)
There is no restriction | limiting in particular in the spinning method of the normal pressure cationic dyeable polyester multifilament of this invention, A conventionally well-known method is employ | adopted. That is, polyethylene terephthalate having an intrinsic viscosity of 0.55 to 0.80 is dried under normal conditions, and melted with a melt extruder such as a screw extruder, for example, a core as disclosed in Japanese Patent No. 3076372. 3-6, more preferably 4-6, small circular openings (5 in FIG. 2) and slits arranged at intervals around the circular discharge hole for forming a portion (3 in FIG. 2) It discharges from the spinneret (FIG. 2) which arrange | positioned the opening part (4 of FIG. 2) which connected the discharge hole for fin part formation, and is 2000-4000 m / min after cooling and solidifying by a conventionally well-known method, More preferably It can be easily obtained by spinning and spinning at a speed of 2500 to 3500 m / min.

  At this time, by changing the radius of the circular discharge hole for forming the core part (b2 in FIG. 2), the length of the tip part of the discharge hole for forming the fin part (a2 in FIG. 2) from the center point of the circular discharge hole, etc. The protrusion coefficient of the fiber cross section can be arbitrarily set to be 0.3 to 0.7. Also, the protrusion coefficient of the fiber cross section can be controlled to some extent by changing the temperature of the spin block and / or the cooling air volume. The cooling air is preferably blown from a cross flow type spinning cylinder having a length of 50 to 100 cm installed so that the upper end is 5 to 15 cm below the spinneret.

  Polyester multifibers having such a fiber cross-sectional shape are subject to rapid orientation crystallization when the spinning take-up speed exceeds 4000 m / min, and the crystallinity tends to exceed 30%. On the other hand, when the spinning take-off speed is less than 2000 m / min, the boiling water shrinkage of the polyester multifiber tends to exceed 70%.

  The polyester multifiber of the present invention thus obtained is supplied to the drawing false twisting process, and is drawn and twisted by setting appropriate conditions according to the fineness of the polyester multifiber and the spinning take-up speed. If the drawn false twisted yarn thus obtained is a fabric such as a woven or knitted fabric according to a conventional method, a fabric having an atmospheric pressure cationic dyeability and excellent water absorption and quick drying performance can be obtained. Further, the fabric has a natural dry feeling and is extremely useful as a clothing fabric.

(Single fiber cross section)
Next, the single fiber cross-sectional shape of the normal pressure cationic dyeable polyester multifiber of the present invention has a protrusion coefficient as defined above of 0.3 to 0.7, more preferably 0.4 to 0.6. It is necessary to exhibit a shape in which 3 to 6, preferably 4 to 6 fin portions (1 in FIG. 1) projecting outward from the fiber cross-section core portion exist.

  The fin portion having a projection coefficient of less than 0.3 does not have a function of forming sufficient capillary voids in the fiber cross section after drawing false twisting, and cannot exhibit water absorption and quick drying performance. Further, such a short fin portion has a tendency to reduce the washing durability of the treatment agent because the anchor effect when the water absorption treatment agent is applied to the fabric is reduced. Also, the texture of the fabric is flat paper-like. On the other hand, the fin portion having a projection coefficient exceeding 0.7 is likely to concentrate the processing tension on the fin portion at the time of drawing false twisting. Water absorption performance is insufficient. Further, yarn breakage (processed yarn) and fluff frequently occur in the drawing false twisting process.

  In addition, even if the fin portion has a protrusion coefficient of 0.3 to 0.7, if the number of the fin portions is 1 to 2 in the single fiber cross section, only a maximum of one fiber cross section closed inside is formed. As a result, there is no sufficient capillary action and water absorption performance is insufficient. Also, the texture of the fabric is flat paper-like. On the other hand, when the number exceeds six, during drawing false twisting, processing tension concentration on the fin portion occurs, partial breakage of the fiber cross section occurs, sufficient capillary formation is not performed, and water absorption performance is insufficient. Become. Further, yarn breakage (processed yarn) and fluff frequently occur in the drawing false twisting process. Note that there may be more than six fin portions having a protrusion coefficient of less than 0.3.

EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated concretely, this invention is not restrict | limited to these Examples. In addition, the analysis item etc. in an Example were measured by the method of the following description.
Intrinsic viscosity:
A dilute solution obtained by dissolving the polyester composition in orthochlorophenol at 100 ° C. for 60 minutes was determined from a value measured at 35 ° C. using an Ubbelohde viscometer. The intrinsic viscosity of the tip is ηC, and the intrinsic viscosity of the undrawn yarn after spinning is ηF.
Diethylene glycol (DEG) content:
The polyester composition chip was decomposed using hydrazine hydrate (hydrated hydrazine), and the content of diethylene glycol in the decomposition product was measured using gas chromatography (HP Hewlett-Packard (HP 6850)).
Tensile strength / elongation of fiber:
Measurement was performed in accordance with the method described in JIS L1070.
Cationic dyeability:
CATHILON BLUE CD-FRLH) 0.2 g / L, CD-FBLH 0.2 g / L (both Hodogaya Chemical), sodium sulfate 3 g / L, acetic acid 0.3 g / L in a staining solution at 100 ° C. for 1 hour, It dye | stained by the bath ratio 1:50, and calculated | required the dyeing | staining rate by following Formula.
Dyeing rate = (OD0−OD1) / OD0
OD0: Absorbance at 576 nm of the dye solution before dyeing
OD1: Absorbance at 576 nm of the dyeing solution after dyeing In the present invention, a dyeing rate of 98% or more was judged as good dyeability.
Projection coefficient:
Take a cross-sectional photomicrograph of the polyester multi-fiber, measure the length (a1) from the center of the inscribed circle of the inner wall of the single fiber cross section to the apex of the fin portion and the radius (b1) of the inscribed circle of the inner wall of the fiber cross section, The projection coefficient was calculated by the following formula.
Projection coefficient = (a1-b1) / a1
Water absorption fast-drying (wicking value):
As an index of water absorption and quick drying performance, according to JIS L1907 fiber product water absorption test method, section 5.1.1 water absorption speed (drop method), the falling water drops from the surface of the test cloth made of polyester false twisted yarn to the surface The number of seconds (wicking value) until no reflection occurred. In addition, L10 represents the wicking value (second) after washing 10 times by JIS L0844-A-2 method.

[Example 1]
(Manufacture of recovered dimethyl terephthalate)
200 parts of ethylene glycol was put into a 500 ml separable flask, 1.5 parts of sodium carbonate, 50 parts of polyethylene terephthalate scraps made of crushed PET bottles, etc. were added, and the temperature was raised to 185 ° C. while stirring. . When this state was maintained for 4 hours, the polyethylene terephthalate waste was dissolved and the depolymerization reaction was completed. The obtained depolymerized product was concentrated by distillation under reduced pressure, and 150 parts of ethylene glycol was recovered as a fraction.

To this concentrated liquid, 0.5 part of sodium carbonate and 100 parts of MeOH were added as a transesterification reaction catalyst, and the liquid temperature was stirred at normal pressure at 75 ° C. for 1 hour to carry out the transesterification reaction.
The resulting mixture was cooled to 40 ° C. and filtered through a glass filter. The crude dimethyl terephthalate recovered on the filter was put into 100 parts of MeOH, heated to 40 ° C. with stirring and washed, and filtered again with a glass filter. This washing was repeated twice.

Crude dimethyl terephthalate that could be captured on the filter was charged into a distillation apparatus and distilled under reduced pressure under a pressure of 6.65 kPa at a reflux ratio of 0.5 to obtain dimethyl terephthalate as a fraction. 47 parts of the fraction could be recovered. The residue in the kettle was measured and the amount of dimethyl terephthalate was measured to be 2 parts, and the reaction rate of dimethyl terephthalate was 93% by weight based on the charged polyester.
In the recovered dimethyl terephthalate purified by distillation, 0.5 weight ppm of dimethyl 2-hydroxyterephthalate was detected. The purified recovered dimethyl terephthalate had a purity of 99.9% by weight or more.

  A mixture of 100 parts by weight of recovered dimethyl terephthalate, 4.1 parts by weight of dimethyl 5-sodium sulfoisophthalate and 60 parts by weight of ethylene glycol was added to 0.03 parts by weight of manganese acetate and 0.12 of sodium acetate trihydrate. A transesterification reaction was performed while adding methanol by weight and gradually raising the temperature from 140 ° C. to 240 ° C. while distilling methanol generated as a result of the reaction out of the system. Thereafter, 0.03 part by weight of orthophosphoric acid was added to complete the transesterification reaction.

  Thereafter, 0.05 parts by weight of antimony trioxide, 2.8 parts by weight of tetrabutoxyphosphonate 5-sulfoisophthalate, 0.3 parts by weight of tetraethylammonium hydroxide, and 0.003 parts by weight of triethylamine were added to the reaction product for polymerization. Move to a container, raise the temperature to 285 ° C., perform a polycondensation reaction at a high vacuum of 30 Pa or less, and terminate the reaction when the agitator power of the polymerization tank reaches a predetermined power or when a predetermined time has elapsed, According to the chip.

The polyester chip thus obtained was dried at 140 ° C. for 5 hours, melted in a screw extruder, passed through a polymer conduit, and loaded into a spin block with a slit width of 0.10 mm and the circular discharge holes shown in FIG. There are four fin-portion forming discharge holes with a length from the center point to the tip (a2 in FIG. 2) of 0.88 mm, and the radius (b2 in FIG. 2) of the core-portion forming circular discharge holes is 0. It was introduced into a spin pack incorporating a spinneret in which 24 groups of 15 mm discharge holes were drilled, and discharged from the spinneret at a discharge rate of 40 g / min. Subsequently, 25 ° C. cooling air was blown into the polymer stream at a rate of 5 Nm ³ / min from a 60 cm long cross-flow type spinning cylinder installed so that the position 10 cm below the spinneret discharge surface was the upper end. Attaching, cooling and solidifying, applying a spinning oil agent, scraping off at a speed of 3000 m / min, polyethylene terephthalate multifibers having crystallinity, boiling water shrinkage, number of fins and projection coefficient shown in Table 1, respectively. Obtained.

  This polyethylene terephthalate multi-fiber is applied to an SDS-8 type drawing false twisting machine (triaxial friction disk false twisting unit, 216 spindles) manufactured by Scragg Co., and a draw ratio of 1.65, a heater temperature of 175 ° C., and a twist number of 3300 times / m, a drawing false twisting process was carried out at a drawing false twisting speed of 600 m / min to obtain a polyethylene terephthalate drawing false twisting yarn having a fineness of 84 dtex. The results are shown in Table 1.

[Comparative Example 1]
The same procedure as in Example 1 was performed except that virgin dimethyl terephthalate was used. The results are shown in Table 1.

  Since the polyester multifibers obtained in the examples showed the same performance as the polyester multifibers that had not undergone the recycling process (from virgin), the recycled polymer was sufficient as an alternative to the polyester multifibers obtained directly from petroleum. Can be used.

  According to the polyester multi-fiber of the present invention, it is possible to reduce the burden on the environment by using a recycled polymer obtained by depolymerizing the polyester waste to the raw material monomer and then polymerizing it again, and when using virgin polyester Equivalent quality fibers can be obtained. In addition, since a drawn false twisted yarn having an appropriate fiber cross-sectional shape and having an appropriate inter-fiber gap can be obtained, a fabric using the drawn false twisted yarn has excellent water absorption and quick drying performance. . In addition, the fabric has a natural dry feel. In addition, highly water-absorbing polyester fibers that are excellent in fastness when wet and can be easily combined with natural fibers can be obtained.

1: Fiber cross-section fin part 2: Fiber cross-section core part 3: Circular discharge hole 4 for core part formation: Slit-like opening part 5 of fin part formation discharge hole: Small circular opening part a1 of fin part formation discharge hole: Length b1 from the center of the inscribed circle of the inner wall of the fiber cross section to the apex of the fin part: Radius of the inscribed circle of the inner wall of the fiber cross section a2: Length from the center of the core part forming discharge hole to the tip of the fin part forming discharge hole B2: radius of the core portion forming discharge hole

Claims (3)

An atmospheric pressure cationic dyeable polyester multifiber characterized by satisfying the following requirements.
a) Recycled dimethyl terephthalate obtained by depolymerizing polyalkylene terephthalate as an ester-forming derivative of an aromatic dicarboxylic acid is used as the polyester, and the dimethyl terephthalate is an ester-forming property of wholly aromatic dicarboxylic acid. It consists of polyester which occupies 80 mol% or more of derivatives.
b) In the acid component constituting the polyester, the metal salt (A) of sulfoisophthalic acid and the compound (B) represented by the following chemical formula (1) are satisfied under the conditions satisfying the following formula 1 and formula 2 at the same time. It must be a copolymerized polyester.
c) The diethylene glycol content in the polyester is 2.5% by weight or less and the intrinsic viscosity is in the range of 0.55 to 1.0.
d) In the cross section orthogonal to the single fiber axis, the protrusion coefficient defined by the following formula is 0.3 to 0.7, and there are 3 to 6 fin portions protruding outward from the fiber cross section core portion. = (A1-b1) / a1
a1: Length from the center of the inscribed circle of the inner wall of the fiber cross section to the top of the fin part b1: Radius of the inscribed circle of the inner wall of the fiber cross section

[In the above formula, R represents hydrogen or an alkyl group having 1 to 10 carbon atoms, and X represents a quaternary phosphonium salt or a quaternary ammonium salt. ]
3.0 ≦ A + B ≦ 5.0 (Formula 1)
0.2 ≦ B / (A + B) ≦ 0.7 (Formula 2)
[Here, A represents the copolymerization amount (mol%) of the metal salt of sulfoisophthalic acid, and B represents the copolymerization amount (mol%) of the compound represented by the chemical formula (1). ]   2. The atmospheric pressure cationic dyeable polyester multifiber according to claim 1, wherein the metal salt of sulfoisophthalic acid is 5-sodium sulfoisophthalic acid.   The normal pressure cationic dyeable polyester multifiber according to claim 1, wherein the compound (B) is 5-sulfoisophthalic acid tetrabutoxyphosphonate.

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