JP2025155994A - Manufacturing method of laminated body - Google Patents

Abstract

To provide a manufacturing method of a laminate capable of inhibiting a poor appearance even when adhered on glass having a complicated curved surface shape.SOLUTION: A manufacturing method of a laminate includes a lamination step of bonding a film on a substrate. The film has a structure in which two or more kinds of thermoplastic resin layers having different main constituents are regularly laminated by 51 to 2001 layers, inclusive. If a direction with a largest shrinkage factor S150(%) at 150°C is an X direction, a direction orthogonal to the X direction within a film surface is a Y direction, a shrinkage factor at 150°C in the X direction is S150X(%), a shrinkage factor at 150°C in the Y direction is S150Y(%), and S150X-S150Y is ΔS150, the film satisfies 0.7≤ΔS150≤10.0. A maximum curvature in the X direction of the film is 0.0001 to 0.1, inclusive, after the lamination step.SELECTED DRAWING: None

Description

The present invention relates to a method for manufacturing a bonded body, a window, an information display device, and an oriented film.

Many products, such as mobile phones, computer housings, electrical appliances, furniture, buildings, and automobiles, require decorative exteriors, and in recent years, demands for decorative exteriors have been increasing. Known methods for imparting decorative exteriors to these products include painting or printing, applying colored film, and transferring the printed surface of printed film onto a substrate. Furthermore, in addition to the demand for decorative exteriors, there is also a growing demand for functionality in these products. For example, a known method involves applying a substrate with additional properties such as heat reflectivity, heat absorption, gas barrier properties, adhesiveness, and conductivity to the product via a heating process.

In recent years, in addition to design appeal, heat-cutting glass, which can prevent the inflow of heat from outside in the summer, especially from sunlight, has been attracting attention in response to carbon dioxide emission restrictions aimed at environmental protection, and attempts have been made to use it in the windows of vehicles such as automobiles and trains, as well as buildings. Examples of how to obtain such heat-cutting glass include a method in which a substrate with heat-cutting properties is attached to glass with a decorative shape by heating, or a method in which a substrate with heat-cutting properties is attached to glass and then heated to give it a decorative shape. Examples of substrates with heat-cutting properties include substrates with a layer containing a heat-absorbing material, substrates on which a metal film is formed by sputtering, and substrates on which multiple thermoplastic resin layers are laminated to block heat rays.

Since such heat-cutting glass is typically used in places where it is visible to the public, its appearance is important. Furthermore, increasing demands for design have led to glass shapes becoming more complex, with multiple curved surfaces and curved surfaces with greater curvature. Therefore, the film or other substrate to be applied must conform to this shape. For example, insufficient conformability can cause wrinkles when applying a film or other substrate to curved glass, or uneven distortions in the film when applying a film or other substrate to glass and then shaping it, resulting in poor appearance. One known cause of these problems is an insufficient thermal shrinkage rate of the film under certain processing conditions, and methods for controlling this thermal shrinkage rate have been proposed (see, for example, Patent Documents 1 and 2).

International Publication No. 2013/137288 JP 2012-81748 A

However, the proposals in Patent Documents 1 and 2 are focused on increasing the thermal shrinkage rate of the film in all directions and suppressing unevenness (improving appearance) after laminating the glass. As a result, sufficient consideration has not been given to suppressing the appearance of bonded bodies obtained by the film bonding process or substrates with complex curved shapes. Therefore, an object of the present invention is to provide a method for manufacturing a bonded body that can suppress poor appearance even when bonded to glass with complex curved shapes, and an oriented film that can be suitably used in the method for manufacturing such a bonded body.

In order to solve the above problems, the present invention comprises the following configurations.
(1) A method for manufacturing a laminated body, comprising a step of laminating a film on a substrate, wherein the film has a structure in which two or more thermoplastic resin layers having different main components are regularly laminated in 51 to 2001 layers, wherein the direction in which the shrinkage rate S ₁₅₀ (%) of the film is greatest at 150°C is the X direction, the direction perpendicular to the X direction in the film plane is the Y direction, the shrinkage rate in the X direction at 150°C is S _150X (%), the shrinkage rate in the Y direction at 150°C is S _150Y (%), and S _150X -S _150Y is ΔS ₁₅₀ , where 0.7≦ΔS ₁₅₀ ≦10.0 is satisfied, and the maximum curvature of the film in the X direction after the laminating step is 0.0001 or more and 0.1 or less.
(2) When the direction in which the curvature of the bonded body is maximum is defined as the A direction, the angle between the X direction and the A direction is 0° or more and 30° or less. The method for producing a bonded body according to (1).
(3) The method for producing a laminate according to (1) or (2), wherein the film satisfies 0.1≦S _150X < 2.5 and −0.6≦S _150Y < 1.8.
(4) The method for producing a bonded body according to (3), wherein the maximum curvature κA in the A direction is 0.0001 or more and 0.0050 or less.
(5) The method for producing a laminate according to any one of (1) to (4), wherein the film satisfies 4.0≦S _150X ≦20.0 and 3.3≦S _150Y ≦19.7.
(6) The method for producing a bonded body according to (5), wherein the maximum curvature κA in the A direction is greater than 0.0050 and not more than 0.1.
(7) The method for producing a laminate according to any one of (1) to (6), wherein the film has a functional layer.
(8) When light having a wavelength of 300 to 2500 nm is incident on the film at an incident angle of 10°, the film has a continuous reflection band with a reflectance of 30% or more and 110% or less over a wavelength width of 20 nm or more and 1000 nm or less. (1) Manufacturing method of a bonded body according to any one of (7) to (7).
(9) The method for producing a laminate according to any one of (1) to (8), wherein the film has an average reflectance of 0% or more and 15% or less at a wavelength of 400 to 700 nm, and an average reflectance of 70% or more and 110% or less at a wavelength of 900 to 1200 nm.
(10) The method for producing a bonded body according to any one of (1) to (9), wherein, when the thickness of the film is D, and among the layer groups divided into two at a position of D/2 from one surface, the layer group having the smaller average layer thickness of the layers constituting each layer group is called layer group A, and the layer group having the thicker average layer thickness is called layer group B, in the attaching step, the film is arranged so that the inner curved surface side is called layer group A.
(11) A window comprising a bonded body obtained by the method for producing a bonded body according to any one of (1) to (10).
(12) An information display device comprising a bonded body obtained by the method for producing a bonded body according to any one of (1) to (10).
(13) An oriented film having a structure in which two or more thermoplastic resin layers having different main components are regularly laminated in 51 to 2001 layers, wherein the direction in which the shrinkage rate S ₁₅₀ (%) at 150°C is the largest is the X direction, the direction perpendicular to the X direction in the film plane is the Y direction, the shrinkage rate in the X direction at 150°C is S _150X (%), the shrinkage rate in the Y direction at 150°C is S _150Y (%), and S _150X -S _150Y is ΔS ₁₅₀ , which satisfies 0.7≦ΔS ₁₅₀ ≦10.0.
(14) The oriented film according to (13), wherein each of the thermoplastic resin layers contains a polyester resin.
(15) The oriented film according to (13) or (14), wherein the outermost layers on both sides of the film are the same layer, and the glass transition temperature of the thermoplastic resin that is the main component of the outermost layers is the highest among the main components of the thermoplastic resin layers that constitute the film.
(16) The oriented film according to any one of (13) to (15), wherein the highest glass transition temperature of the oriented film is 90° C. or higher and 140° C. or lower.
(17) The oriented film according to any one of (13) to (16), wherein the difference between the in-plane average refractive index and the perpendicular refractive index in at least one layer other than the outermost layer constituting the film is 0.01 or more and 0.30 or less.
(18) The oriented film according to any one of (13) to (17), having an in-plane retardation of 1,500 nm or more and 10,000 nm or less.
(19) The oriented film according to any one of claims (13) to (18), which satisfies 0.1≦S _150X <2.5 and −0.6≦S _150Y <1.8.
(20) The oriented film according to any one of (13) to (19), which satisfies 4.0≦S _150X ≦20.0 and 3.3≦S _150Y ≦19.7.
(21) The oriented film according to any one of (13) to (20), which has a reflection band in which the reflectance is continuous over a wavelength range of 20 nm to 1000 nm when light having a wavelength of 300 to 2500 nm is incident at an incident angle of 10°.
(22) The oriented film according to any one of (13) to (21), having an average reflectance of 0% or more and 15% or less in the wavelength range of 400 to 700 nm, and an average reflectance of 70% or more and 110% or less in the wavelength range of 900 to 1200 nm.

The present invention provides a method for manufacturing a bonded body that can suppress appearance defects even when a film is attached to glass with a complex curved surface shape, and an oriented film that can be suitably used in the manufacturing method of such a bonded body.

The present invention is described in detail below, but the present invention should not be construed as being limited to the specific embodiments, including the examples below. Various modifications that achieve the object of the invention and do not deviate from the gist of the invention are included within the scope of the present invention.

The method for producing a bonded body of the present invention includes a bonding step of bonding a film onto a substrate, wherein the film has a configuration in which two or more thermoplastic resin layers having different main components are regularly laminated in 51 to 2001 layers, and wherein, when the direction in which the shrinkage rate S ₁₅₀ (%) of the film is greatest at 150°C is the X direction, and the direction perpendicular to the X direction in the film plane is the Y direction, the shrinkage rate in the X direction at 150°C is S _150X (%), the shrinkage rate in the Y direction at 150°C is S _150Y (%), and S _150X -S _150Y is ΔS ₁₅₀ , the method for producing a bonded body satisfies 0.7≦ΔS ₁₅₀ ≦10.0, and the maximum curvature of the film in the X direction after the bonding step is 0.0001 or more and 0.1 or less.

<Film>
The method for manufacturing a laminate of the present invention includes a bonding step of bonding a film to a substrate. In the method for manufacturing a laminate of the present invention, the film has a structure in which two or more thermoplastic resin layers having different main components are regularly laminated in a total of 51 to 2001 layers. Here, the term "thermoplastic resin layer" refers to a layer whose main component is a thermoplastic resin, i.e., a layer containing a total of more than 50% by mass but not more than 100% by mass of thermoplastic resin when the entire layer is taken as 100% by mass. Examples of minor components that are not the main component of the thermoplastic resin layer include inorganic components and low-molecular-weight organic components other than thermoplastic resins. Specific examples include light absorbers (ultraviolet absorbers, dyes, pigments, heat absorbers), antioxidants, light stabilizers, quenchers, heat stabilizers, weather stabilizers, organic lubricants, fillers, antistatic agents, nucleating agents, and flame retardants. These minor components can be freely added to each layer to the extent that the original physical properties and functions of the film are not impaired.

Of these minor components, depending on the type of thermoplastic resin that makes up each thermoplastic resin layer, absorption of high-energy ultraviolet light may accelerate degradation. Therefore, it is preferable to include an ultraviolet absorber to inhibit photodegradation by promoting reaction competition. Furthermore, light absorbers such as ultraviolet absorbers may themselves be affected by degradation due to heat and oxygen, or photodegradation due to reactions with ultraviolet light and oxygen, during the resin extrusion process in film production. Therefore, antioxidants for the former, and light stabilizers and quenchers for the latter, can both be added as additives to layers containing thermoplastic resins that are susceptible to degradation, to the extent that the film's inherent properties and functions are not impaired.

Representative thermoplastic resins that can be used to form the thermoplastic resin layer in the film used in the manufacturing method of the laminate of the present invention are listed below, but are not limited to these. Thermoplastic resins that can be suitably used in the thermoplastic resin layer of the film include, for example, polyolefin resins such as polyethylene, polypropylene, poly(1-butene), poly(4-methylpentene), polyisobutylene, polyisoprene, polybutadiene, polyvinylcyclohexane, polystyrene, poly(α-methylstyrene), poly(p-methylstyrene), polynorbornene, and polycyclopentene; polyamide resins such as nylon 6, nylon 11, nylon 12, and nylon 66; and copolymers of vinyl monomers such as ethylene/propylene copolymer, ethylene/vinylcyclohexane copolymer, ethylene/vinylcyclohexene copolymer, ethylene/alkyl acrylate copolymer, ethylene/acrylic methacrylate copolymer, ethylene/norbornene copolymer, ethylene/vinyl acetate copolymer, propylene/butadiene copolymer, isobutylene/isoprene copolymer, and vinyl chloride/vinyl acetate copolymer. Resins include acrylic resins such as polyacrylate, polyisobutyl methacrylate, polymethacrylate, polymethyl methacrylate, polybutyl acrylate, polyacrylamide, and polyacrylonitrile; polyester resins such as polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, and polyethylene-2,6-naphthalate; biodegradable polymers such as polylactic acid and polybutyl succinate; and others, including polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyvinyl butyral, polyacetal, polyglycolic acid, polycarbonate, polyketone, polyethersulfone, polyetheretherketone, modified polyphenylene ether, polyphenylene sulfide, polyetherimide, polyimide, polysiloxane, tetrafluoroethylene resin, trifluoroethylene resin, trifluorochloroethylene resin, tetrafluoroethylene-hexafluoropropylene copolymer, and polyvinylidene fluoride.

In each thermoplastic resin layer, these thermoplastic resins may be used alone, or two or more types of thermoplastic resins may be used as a blend or alloy. Blending or alloying can provide physical and chemical properties that cannot be obtained from a single type of thermoplastic resin. Furthermore, when laminating thermoplastic resin layers with significantly different skeletal structures, if a thermoplastic resin layer on one side of adjacent thermoplastic resin layers is given a copolymer component that shares a polymer skeletal structure with the thermoplastic resin layer on the opposite side, interlayer adhesion at the interface can be improved.

In each thermoplastic resin layer constituting the film used in the manufacturing method of the laminate of the present invention, from the viewpoints of rheological properties related to strength, heat resistance, transparency, and lamination, it is preferable that the thermoplastic resin serving as the main component be selected from polyolefin resin, polyester resin, acrylic resin, polycarbonate resin, and polyamide resin. Among these, from the viewpoints mentioned above, polyester resin is more preferably used, and it is more preferable that at least one of the thermoplastic resin layers is a polyester resin layer (a layer containing polyester resin as the main component). Even more preferable is a polyester resin obtained by polymerization of a monomer containing an aromatic dicarboxylic acid or aliphatic dicarboxylic acid and a diol as the main components.

Examples of aromatic dicarboxylic acids include terephthalic acid, isophthalic acid, phthalic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-diphenyldicarboxylic acid, 4,4'-diphenyletherdicarboxylic acid, and 4,4'-diphenylsulfonedicarboxylic acid. Examples of aliphatic dicarboxylic acids include adipic acid, suberic acid, sebacic acid, dimer acid, dodecanedioic acid, cyclohexanedicarboxylic acid, and their ester derivatives. Of these, terephthalic acid and 2,6-naphthalenedicarboxylic acid are preferred. These acid components may be used alone or in combination, and may also be partially copolymerized with oxyacids such as hydroxybenzoic acid.

Examples of diol components include ethylene glycol, 1,2-propanediol, 1,3-propanediol, neopentyl glycol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, diethylene glycol, triethylene glycol, polyalkylene glycol, 2,2-bis(4-hydroxyethoxyphenyl)propane, isosorbate, and spiroglycol. Among these, ethylene glycol is preferred. These diol components may be used alone or in combination.

In each thermoplastic resin layer constituting the film used in the method for producing a bonded body of the present invention, it is particularly preferable to use, as the main component, a polyester resin selected from the above polyester resins, particularly polyethylene terephthalate and copolymers thereof, polyethylene naphthalate and copolymers thereof, polybutylene terephthalate and copolymers thereof, polybutylene naphthalate and copolymers thereof, polyhexamethylene terephthalate and copolymers thereof, and polyhexamethylene naphthalate and copolymers thereof.

The film used in the method for producing a laminate of the present invention has a structure in which two or more thermoplastic resin layers, each having a different main component, are regularly laminated in a total of 51 to 2001 layers. This structure allows the film to have functions that cannot be achieved with a single layer. For example, it is possible to impart light reflection, and this function improves as the number of layers increases based on the principle of interference reflection. From this perspective, the total number of thermoplastic resin layers is preferably 201 or more, and more preferably 401 or more. Increasing the number of film layers enhances the interference reflection function derived from the lamination; for example, if the reflection band is near infrared or near infrared, it is possible to improve heat ray blocking performance, etc. On the other hand, from the perspective of reducing the size of the lamination equipment, the upper limit for the number of thermoplastic resin layers is approximately 2001.

By using the film used in the manufacturing method of the bonded body of the present invention as described above, it becomes easy to achieve functions such as selectively reflecting light in a specific wavelength band through interference reflection, or reflecting light of a specific polarization, depending on the relationship between the difference in refractive index of each layer and the layer thickness. For example, if a film is made to have the function of reflecting infrared light, then by adhering this film to a substrate (e.g., glass), it can be made into glass with high heat-shielding performance. Alternatively, if a film is made to have the function of reflecting light of a specific polarization, then by adhering this film to a substrate (e.g., glass), it can be made into a glass component suitable for a display device that displays images with a specific polarization.

In the film used in the method for manufacturing a laminate of the present invention, the term "different" as the main component of the thermoplastic resin layer means that the components constituting the thermoplastic resin layer differ by more than 50% by mass. However, if this is difficult to specify, this can be substituted by at least one of the following: (1) different glass transition temperatures or melting points in differential scanning calorimetry (DSC), or (2) different contrast in images after dyeing when cross-sectionally observed with a transmission electron microscope (TEM).

Different major components can be determined by the fact that the thermoplastic resin layers constituting the film exhibit different melting points and/or glass transition points in differential scanning calorimetry (DSC). In the present invention, "different melting points" and "different glass transition temperatures" refer to melting points or glass transition points that differ by 0.1°C or more, preferably 2°C or more. On the other hand, thermoplastic resin layers may not exhibit glass transition or melting points. If one thermoplastic resin layer exhibits a glass transition or melting point and the other does not, this cannot be calculated as a temperature difference, but is interpreted as the thermoplastic resin layers having different major components. In the present invention, DSC measurements can be performed in the temperature range of 25°C to 300°C, in accordance with JIS-K-7122 (1987).

The above-mentioned methods require the relevant thermoplastic resin layers to be separated from the film for analysis, but separating the layers can be difficult depending on the layer structure of the film. Therefore, for simplicity, in this invention, layer interfaces can be recognized by contrast differences in cross-sectional images observed using a transmission electron microscope. If it is confirmed that the difference in the average brightness of two adjacent layers is greater than any of the standard deviations of brightness within each adjacent thermoplastic resin layer using the method described below in the Layer Interface (Contrast Difference) section of the measurement method, the contrast of the dyed images can be determined to be different, and the main components of adjacent thermoplastic resin layers can be determined to be "different."

This contrast difference arises due to differences in electron beam scattering, crystal diffraction, etc. between thermoplastic resin layers. Therefore, if the main components of the thermoplastic resin layers differ according to the criteria described above, the crystallinity and electron density state will differ depending on the type of thermoplastic resin that makes up each thermoplastic resin layer and the copolymerization amount of the combined thermoplastic resin, and the electron dyeing state will also differ. In other words, if the film has thermoplastic resin layers with different main components, each thermoplastic resin layer can be visually recognized as a layer structure with a contrast difference in a cross-sectional image of the film. The presence or absence of a contrast difference can be evaluated using the method described below.

From the standpoint of interlayer adhesion and high-precision laminate structure, it is preferable that the regularly laminated thermoplastic resin layers used in the manufacturing method of the laminate of the present invention each contain, as a main component, a thermoplastic resin containing the same basic skeleton. The basic skeleton is the repeating unit most commonly contained in the molecular chain; for example, in the case of polyethylene terephthalate, this corresponds to the ethylene terephthalate unit, and in the case of polyethylene, this corresponds to the ethylene unit.

When the film used in the method for producing a laminate of the present invention has a configuration in which two types of thermoplastic resin layers (referred to as A1 layer and B1 layer) having different main components are alternately laminated, a preferred combination of thermoplastic resins used as the main components of A1 layer and B1 layer is one in which the thermoplastic resin that is the main component of A1 layer and the thermoplastic resin that is the main component of B1 layer have the same basic skeleton. When the thermoplastic resins that are the main components of each layer have the same basic skeleton, lamination precision is high and delamination at the lamination interface is less likely to occur.

To impart different properties to thermoplastic resins with the same basic skeleton, it is preferable to use a copolymer as the main component of one layer, or to use a copolymer as the main component of both layers, but with different types or amounts of copolymerized units. An example of the former is a configuration in which one layer's main component is homopolyethylene terephthalate, while the other layer's main component is a polyester resin composed of ethylene terephthalate units and repeating units with other ester bonds. The proportion of the other repeating units (sometimes referred to as the copolymerization amount) is preferably 5 mol% or more to achieve different properties, while less than 50 mol% is preferred because it provides excellent adhesion between layers and minimizes differences in thermal flow properties, resulting in excellent thickness accuracy and uniformity of each layer. A ratio of 10 mol% to 45 mol% is even more preferable. An example of the latter is a configuration in which each layer's main component is a polyester resin composed of ethylene terephthalate units and repeating units with other ester bonds, but with different copolymerization amounts. It is also desirable that the A1 layer and the B1 layer each be a blend or alloy of multiple types of thermoplastic resins. By blending or alloying multiple types of thermoplastic resins, it is possible to obtain performance that cannot be obtained with a single type of thermoplastic resin.

In addition, a preferred combination of thermoplastic resins used as the main components of the A1 layer and the B1 layer of the film used in the manufacturing method of the laminate of the present invention is one in which the difference in glass transition temperature between the thermoplastic resins is 20°C or less. A difference in glass transition temperature of 20°C or less improves thickness uniformity when forming the laminate film, resulting in more uniform reflection characteristics. It also reduces the occurrence of overstretching when forming the film.

When the film of the present invention has a layer structure in which A1 layers and B1 layers are alternately laminated and the A1 layers are disposed as the outermost layers on both sides, if the difference in glass transition temperature between the thermoplastic resin that is the main component of A1 layer (thermoplastic resin A1) and the thermoplastic resin that is the main component of B1 layer (thermoplastic resin B1) is greater than 5°C, it is more preferable that the glass transition temperature of thermoplastic resin A1 is higher than the glass transition temperature of thermoplastic resin B1. The relatively high glass transition temperature of A1, the outermost layer, reduces adhesion to rolls or clips during longitudinal stretching or transverse stretching, preventing deterioration in appearance quality.

In the film used in the method for producing a laminate of the present invention, the difference in the in-plane average refractive index between the A1 layer and the B1 layer is preferably 0.03 or more. It is more preferably 0.05 or more, and even more preferably 0.10 or more. When the difference in the in-plane average refractive index between the A1 layer and the B1 layer is 0.03 or more, sufficient reflectance is obtained, resulting in improved heat-ray blocking performance, for example. One method for achieving the difference in the in-plane average refractive index between the A1 layer and the B1 layer within the above range is to use an embodiment in which one of the thermoplastic resins A1 and B1 is crystalline and the other is amorphous. Crystalline here means that the enthalpy of fusion is 10 J/g or more in differential scanning calorimetry (DSC). Similarly, amorphous means that the enthalpy of fusion is less than 10 J/g.

When the main components are such a combination of thermoplastic resins, it is easy to achieve an in-plane average refractive index difference during the stretching and heat treatment processes in film production. Furthermore, with such a combination of resins, orientation can be alleviated by performing heat treatment at a temperature that is much higher than the glass transition temperature of the amorphous polyester and below the melting point of the crystalline polyester.

In the case of amorphous thermoplastic resins, the refractive index usually does not change during the stretching and heat treatment processes used in film production, so the refractive index can also be measured by vacuum drying the thermoplastic resin and then pressing it into a sheet, if necessary. The in-plane average refractive index refers to the average value of the refractive index in the X and Y directions (described below) (details on how to identify each direction and how to measure the refractive index will be described later).

As an example of a resin combination that satisfies the above conditions, in the film of the present invention, it is preferable that the A1 layer be primarily composed of polyethylene terephthalate or polyethylene naphthalate, and the B1 layer be primarily composed of a polyester having the same basic structure as the primary component of the A1 layer and containing spiroglycol. Polyester containing spiroglycol refers to a copolyester copolymerized with spiroglycol, or a polyester blended with a copolyester copolymerized with a homopolyester and spiroglycol. Polyester containing spiroglycol is preferred because it has a small difference in glass transition temperature from polyethylene terephthalate or polyethylene naphthalate, making it less susceptible to overstretching during molding and less susceptible to delamination. From the above perspective, a more preferable embodiment is one in which the A1 layer is primarily composed of polyethylene terephthalate or polyethylene naphthalate, and the B1 layer is primarily composed of a polyester having the same basic structure as the primary component of the A1 layer and containing spiroglycol and cyclohexanedicarboxylic acid. When the B1 layer is primarily composed of a polyester resin containing spiroglycol and cyclohexanedicarboxylic acid, the difference in in-plane refractive index between it and polyethylene terephthalate or polyethylene naphthalate is large, making it easier to achieve high reflectance by alternately laminating the A1 and B1 layers. Furthermore, this type of polyester has a small difference in glass transition temperature between it and polyethylene terephthalate or polyethylene naphthalate, and also has excellent adhesive properties. Therefore, overstretching during film formation is unlikely, and delamination between the A1 and B1 layers can be reduced.

The copolymerization amount of the polyester containing spiro glycol and cyclohexanedicarboxylic acid is preferably 5 mol% to 30 mol% for spiro glycol and 5 mol% to 30 mol% for cyclohexanedicarboxylic acid. The copolymerization amount of the polyester containing spiro glycol is preferably 5 mol% or more and less than 50 mol%. When using a polyester containing spiro glycol and cyclohexanedicarboxylic acid, it is also preferable to blend a small amount of polyethylene terephthalate. This configuration suppresses the denaturation of the polyester resin due to heating when the film is heated to form a laminate with a curvature, making it easier to suppress poor appearance of the resulting laminate. From this perspective, the blend ratio of the polyester resin containing spiro glycol and cyclohexanedicarboxylic acid to polyethylene terephthalate is preferably 95:5 to 70:30.

Other preferred embodiments include those in which the A1 layer contains a small amount of the thermoplastic resin that is the main component of the B1 layer, those in which the B1 layer contains a small amount of the thermoplastic resin that is the main component of the A1 layer, and those that combine both of the above. By blending small amounts of the thermoplastic resin that is the main component of either the A1 layer or the B1 layer, or both, into these layers, high-precision lamination, improved interlayer adhesion, and improved stretchability during film formation can be achieved. In these embodiments, the blend ratio is preferably between 5% and 30% by weight, with the entire layer being taken as 100% by weight.

Furthermore, the film used in the method for manufacturing a laminate of the present invention preferably has a regular arrangement consisting of the A2 layer, the B2 layer, and the C2 layer, where the three thermoplastic resin layers have different main components and are designated as the A2 layer, the B2 layer, and the C2 layer, respectively. Here, regular arrangement refers to a laminate structure in which three thermoplastic resin layers having "different" main components are laminated in a regular arrangement, as defined above. In this case, the three thermoplastic resin layers having different main components may each be formed from a thermoplastic resin having a different skeletal structure, or thermoplastic resins having two different skeletal structures may be used, with the three thermoplastic resin layers being designed to have different blend ratios or copolymerization amounts. For convenience, hereafter in this specification, the thermoplastic resin layers having different main components will be defined alphabetically as the A2 layer, the B2 layer, and the C2 layer in the order in which they first appear when viewed from the outermost surface of the film, and the thermoplastic resins that are the main components of each thermoplastic resin layer will be defined as the thermoplastic resin A2, the thermoplastic resin B2, and the thermoplastic resin C2.

If the different thermoplastic resin layers are defined as layer A2, layer B2, and layer C2 in the order in which they are arranged from the outermost surface of the laminate film, examples of the regular arrangement possessed by the film used in the first invention include (ABC)x, (ABCB)x, (ABAC)x, (ABCAB)x, (ABCAC)x, (ABABC)x, and (ABCBCB)x (the numbers in parentheses represent the regular arrangement, and x is a natural number indicating the number of repetitions. A, B, and C represent layer A2, layer B2, and layer C2, respectively. Note that similar notations may be used hereinafter in describing regular arrangements consisting of layer A2, layer B2, and layer C2). In particular, to ensure that films made from thermoplastic resins with different physical/chemical properties, such as skeletal structure, viscoelasticity, and viscosity characteristics, maintain their laminated structure over the long term without interfacial delamination and without impairing their necessary functions, it is necessary to consider combinations of thermoplastic resin layers that have good compatibility (miscibility, surface free energy, etc.) with the adjacent thermoplastic resin layers that form the interface between the different thermoplastic resin layers contained in the film.

Therefore, to avoid complicating the resin design of the entire film, it is preferable to limit the number of different interface combinations formed between adjacent thermoplastic resin layers. Specifically, there are three types of interfaces formed between three different types of thermoplastic resin layers: the A2-B2 interface, the B2-C2 interface, and the C2-A2 interface. However, among the regular arrangements, (ABCB)x and (ABCBCB)x are preferred because only two types exist: the A2-B2 interface and the B2-C2 interface. In such an embodiment, the resin design should be such that delamination between the A2 layer and the B2 layer, and between the B2 layer and the C2 layer, is unlikely to occur, and the combination of the A2 layer and the C2 layer does not need to be given much consideration.

In the method for producing a bonded body of the present invention, the film used in the method must satisfy 0.7≦ΔS _{150 ≦10.0, where the direction with the largest shrinkage rate S 150} (%) at 150°C is the X direction, the direction perpendicular to the X direction in the film plane is the Y direction, the shrinkage rate in the X direction at 150°C _{is S 150X (} %), the shrinkage rate in the Y direction at 150°C is S _150Y (%), and S _150X -S _150Y is ΔS _150. Here, the X direction is defined as the direction with the largest S 150 among any one direction in a plane parallel to the film surface and the directions rotated from that direction up to 180° at 5 _° intervals in an in-plane direction parallel to the film surface. The shrinkage rate can be determined from a thermal shrinkage curve measured by thermomechanical analysis under conditions of a temperature of 25°C to 200°C and a heating rate of 10°C/min, where a positive value indicates shrinkage and a negative value indicates expansion, based on the length at 25°C (the specific measurement method will be described later).

By using this configuration, when a film is applied to a curved substrate, the film shrinks upon heating, allowing it to conform to the curved shape, resulting in a bonded product with no defects in appearance. If conformance to a curved shape depends on the shrinkage rate, a method of controlling the shrinkage rate of the film in the same way in all directions is also possible. However, as substrates become more complexly curved due to improved design, if the thermal shrinkage rate is the same in all directions, the suppression of defects in appearance will be limited to specific locations. For example, in a substrate with a single curved surface, where the curvature differs between the left-right and up-down directions, problems such as suppressing defects in appearance in the direction with the greater curvature but not in the direction with the smaller curvature may occur (details of the substrate shape are discussed below). Alternatively, in the case of a substrate with multiple curved surfaces, the suppression of defects in appearance may be possible in one curved surface but not in the other curved surfaces. Furthermore, controlling the shrinkage rate of the film in the same way in all directions imposes many restrictions on the film's manufacturing conditions and the type of thermoplastic resin that constitutes it, often resulting in a deterioration of film properties other than its ability to conform to a curved surface. As a result of extensive research, the inventors discovered that by imparting anisotropy to the film's thermal shrinkage, it is possible to maintain film properties other than its ability to conform to curved shapes, while allowing the film to conform well to substrates with complex curved shapes and reduce appearance defects.

A method for imparting the property of 0.7≦ΔS ₁₅₀ ≦10.0 to the film used in the manufacturing method of the laminate of the present invention will be described below with an example. For example, a method can be used in which an unoriented sheet formed by a melt extrusion process and a casting process is stretched in the longitudinal or width direction to form a uniaxially oriented film. In the case of a uniaxially oriented film, the stretching direction is the direction in which the shrinkage rate S ₁₅₀ (%) is greatest, i.e., the X direction. Here, the longitudinal direction refers to the running direction of the sheet or film (the winding direction of the film in the case of a film roll), and the width direction refers to the direction perpendicular to the longitudinal direction within the film plane.

As another example, a method can be used in which a biaxially oriented film is obtained by stretching an unoriented sheet formed by a melt extrusion process and a casting process in the longitudinal and width directions. In this case, stretching can be performed sequentially in both directions or simultaneously in both directions. To give a biaxially oriented film the property of 0.7≦ΔS ₁₅₀ ≦10.0, methods include: setting a difference in the stretching ratio between the longitudinal direction and the width direction; performing a relaxation treatment in the longitudinal direction between stretching in the longitudinal direction and stretching in the width direction; performing a relaxation treatment in the width direction after biaxial stretching; adjusting the heat treatment temperature and the conditions for the relaxation treatment in the width direction; and further stretching in the width direction after biaxial stretching (additional width direction stretching). In the method of setting a difference in the stretching ratio between the longitudinal direction and the width direction, the direction with the highest stretching ratio is the longitudinal direction; in the method of performing a relaxation treatment in the longitudinal direction, the longitudinal direction is the longitudinal direction; and in the method of performing a relaxation treatment in the width direction and additional width direction stretching, the width direction is the width direction. In other words, the shrinkage ratio S ₁₅₀ (%) is the X direction. These methods may be combined as appropriate.

The film used in the method for producing a laminate of the present invention is preferably a biaxially oriented film from the viewpoints of toughness and ease of handling. Furthermore, from the viewpoint of maintaining film properties other than conformability to curved surface shapes, a method in which width-direction relaxation treatment and width-direction additional stretching are performed is even more preferable.

It is also preferable that the film used in the method for producing a bonded body of the present invention has, on at least one surface, a reflection band with a continuous reflectance of 30% to 110% over a wavelength range of 20 nm to 1000 nm when light with a wavelength of 300 to 2500 nm is incident at an incident angle of 10°. Details of measuring each optical property will be described later, but the incident angle refers to the angle with the normal to the film surface. "On at least one surface" means that the requirements must be met when reflectance is measured with light applied to at least one surface. Hereinafter, "on at least one surface" in measuring optical properties will be interpreted in the same way.

When the film used in the method for producing a laminate of the present invention has the above-described properties, for example, a reflection band in the wavelength range of 400 to 700 nm, it can be colored by visible light, providing decorative properties (design). When the reflection band has a wavelength of 850 nm or more, it can provide heat-shielding properties. From the viewpoint of enhancing each property, a wavelength width of 100 nm or more is more preferable, and a wavelength width of 300 nm or more is even more preferable. From the above viewpoint, the wider the wavelength width of the reflection band, the more preferable it is, but from the viewpoint of feasibility, the upper limit is 1000 nm. Here, the maximum reflectance in the reflection band exceeds 100% because the reflectance referred to here is the relative reflectance based on a white aluminum oxide plate (details of the measurement method will be described later). Note that, as a means for obtaining a film with at least one continuous reflection band with a reflectance of 30% or more over a wavelength width of 20 nm or more, the number and thickness of the thermoplastic resin layers in the film can be adjusted. More specifically, the width of the reflection band can be widened by increasing the number of layers.

The film used in the method for producing a bonded body of the present invention preferably has an average reflectance of 0% to 15% in wavelengths of 400 to 700 nm, and an average reflectance of 70% to 110% in wavelengths of 900 to 1200 nm. By adopting such an embodiment, when applied to the windows of a building or automobile, for example, it is possible to enhance the heat shielding properties of the interior (car interior) by reflecting infrared rays while maintaining aesthetic appearance and the view and visibility from the interior (car interior). From the perspective of heat shielding properties, an average reflectance of 80% or more in wavelengths of 900 to 1200 nm is more preferable. Meanwhile, the upper limit of this average reflectance is 105% from the perspective of feasibility.

One method for obtaining such a film is to make the sum of the optical thicknesses of adjacent layers 400 to 700 nm for the majority of the thermoplastic resin layers that make up the film. Optical thickness here refers to the product of the layer thickness of each layer and the refractive index of the resin that makes up the layer. The sum of the optical thicknesses of adjacent layers determines the wavelength at which interference reflection occurs in the film. Interference reflection from a film in which the sum of the optical thicknesses of adjacent layers is 400 to 700 nm typically occurs in the wavelength range of approximately 800 to 1400 nm, making it easy to achieve an average reflectance of 70% or more and 110% or less in the wavelength range of 900 to 1200 nm. Furthermore, the magnitude of reflectance increases with the number of layers and the difference in the in-plane average refractive index of adjacent layers. A film in which the sum of the optical thicknesses of adjacent layers for the majority of layers is 400 to 700 nm easily achieves efficient improvement in average reflectance in the wavelength range of 850 to 1200 nm.

Another example of a film having an average reflectance of 70% or more in the wavelength range of 900 to 1200 nm is one in which the layer thickness distribution of two types of thermoplastic resin layers (A1 layer, B1 layer) having different main components is such that the optical thicknesses of the adjacent A1 layer and B1 layer simultaneously satisfy the following formulas 1 and 2:
Formula 1: λ=2(n _α d _α +n _β d _β )
Equation 2: n _α d _α = n _β d _β
Here, λ is the reflection wavelength, _nα is the in-plane refractive index of the A1 layer, _dα is the thickness of the A1 layer, _nβ is the in-plane refractive index of the B1 layer, and _dβ is the thickness of the B1 layer. Having a layer thickness distribution that simultaneously satisfies both Equation 1 and Equation 2 can eliminate even-order reflections. Therefore, it is possible to increase the average reflectance in the wavelength range of 900 nm to 1200 nm while lowering the average reflectance in the visible light wavelength range of 400 to 700 nm, resulting in a transparent film with excellent heat-ray blocking performance. Generally, the refractive index of a film after molding and stretching a thermoplastic resin is approximately 1.4 to 1.9. Therefore, by setting the thickness ratio of the adjacent A1 layer to the B1 layer (thickness of the A1 layer/thickness of the B1 layer) to 0.7 or more and 1.4 or less, a film with suppressed even-order reflections can be obtained. Therefore, it is preferable to set the thickness ratio of the adjacent A1 layer to the B1 layer (thickness of the A1 layer/thickness of the B1 layer) to 0.7 or more and 1.4 or less. More preferably, it is 0.8 or more and 1.2 or less.

As another example of a layer thickness distribution, the 711711 configuration (U.S. Patent No. 5,360,659) is also preferred. The 711711 configuration refers to a stacked structure in which six layers, each consisting of an A1 layer and a B1 layer stacked in the order ABABAB, form one repeating unit, with the optical thickness ratio within the unit being 711711 (A refers to the A1 layer, and B refers to the B1 layer). A layer thickness distribution with the 711711 configuration can eliminate high-order reflections. This allows for a high average reflectance in the wavelength range of 900 to 1200 nm while a low average reflectance in the wavelength range of 400 to 700 nm, resulting in a transparent film with excellent thermal energy blocking performance. It is also preferred to use a layer thickness distribution that simultaneously satisfies both Equations 1 and 2 for reflections in the wavelength range of 900 to 1200 nm, thereby achieving a layer thickness distribution with the 711711 configuration for reflections in the wavelength range of 1200 to 1400 nm. This layer thickness configuration allows for efficient light reflection with a small number of layers.

One embodiment of the film used in the method for producing a bonded body of the present invention is one in which the refractive index of at least one surface of the film is 1.68 or more and 1.80 or less. A refractive index of 1.68 or more makes it easy to increase the reflectance in the reflection band. If the refractive index is higher than 1.80, the difference in chemical structure will be greater, which can deteriorate the lamination ability of thermoplastic resin A1 and thermoplastic resin B1, resulting in clouding of the film and significant peeling at the interface between the A1 layer and the B1 layer.

An example of a method for achieving a refractive index of 1.68 or more and 1.80 or less on at least one surface of the film is to use a method in which the main dicarboxylic acid unit of thermoplastic resin A1 is a naphthalenedicarboxylic acid unit. This method allows for an in-plane refractive index difference between the A1 layer and the B1 layer, making it easier to obtain a laminated polyester film with superior reflective performance. Furthermore, in order to increase the in-plane refractive index difference between the A1 layer and the B1 layer, it is also preferable that thermoplastic resin B1 be an amorphous resin. To incorporate naphthalenedicarboxylic acid into the dicarboxylic acid constituents of thermoplastic resin A1 of the film, a method can be used in which naphthalenedicarboxylic acid is included in the dicarboxylic acid constituents of the raw material polyester resin that constitutes thermoplastic resin A1.

Preferred layer thickness distributions include one in which the layer thickness increases or decreases from one side of the film to the opposite side, one in which the layer thickness increases from one side of the film toward the center and then decreases, and one in which the layer thickness decreases from one side of the film toward the center and then increases. Preferred layer thickness distributions vary continuously, such as linearly, geometrically, or with a difference progression, or one in which approximately 10 to 50 layers have approximately the same layer thickness and the layer thickness changes in a stepwise manner.

The film used in the manufacturing method of the laminate of the present invention can preferably have a protective layer with a layer thickness of 3 μm or more on both surface layers. The thickness of the protective layer is preferably 5 μm or more, and more preferably 10 μm or more. By providing a protective layer or increasing the thickness of the protective layer, it is possible to easily improve the appearance of the obtained film (suppressing flow marks) and obtain the effect of suppressing ripples in the transmittance and reflectance spectra.

The film used in the method for producing a laminate of the present invention preferably has the same outermost layer on both sides, and the thermoplastic resin that is the main component of the outermost layer has the highest glass transition temperature of the main components of the thermoplastic resin layers that make up the film. Having the same outermost layer on both sides of the film makes it easier to produce the film. Furthermore, by using a thermoplastic resin that has the highest glass transition temperature of the main components of the thermoplastic resin layers that make up the film as the outermost layer on both sides of the film, it is possible to easily prevent poor appearance when the film is applied to a substrate with a curved surface.

The highest glass transition temperature among the main components of the thermoplastic resin layer constituting the film used in the manufacturing method of the laminate of the present invention is preferably 90°C or higher and 140°C or lower. The bonding process involves heating, and the heating temperature is generally high, at 100°C or higher. In such a bonding process, if the glass transition temperature of the thermoplastic resin layer is lower than 90°C, the heat of the bonding process may cause the layer to soften, resulting in deformation and poor appearance, or deterioration of film properties other than shape conformity. Furthermore, if the glass transition temperature is higher than 140°C, depending on the shape to be bonded, the film may not shrink sufficiently even when heated, making it unable to conform to the shape. By using a thermoplastic resin layer of the above-mentioned aspect, it is possible to maintain the properties of the film, suppress poor appearance due to the heat of the bonding process, and impart excellent shape conformity to even complex shapes.

Of the layers other than the outermost layer constituting the film used in the method for producing a bonded body of the present invention, it is preferable that the difference between the in-plane average refractive index and the in-plane normal refractive index in at least one layer is 0.01 or more and 0.30 or less. A difference of 0.01 or more between the in-plane average refractive index and the in-plane normal refractive index indicates in-plane orientation, which means that the heat resistance of the layer in question is high. If the difference between the in-plane average refractive index and the in-plane normal refractive index is less than 0.01, the film will have low heat resistance, which may cause it to soften due to heat during the bonding process and deform, resulting in poor appearance. Furthermore, if the difference between the in-plane average refractive index and the in-plane normal refractive index is greater than 0.03, the difference in the in-plane average refractive index from the other layers constituting the film will be small, which may deteriorate film properties other than shape conformance, or the heat resistance may be so high that, depending on the shape to be bonded, the film may not shrink sufficiently even when heated, making it unable to conform to the shape. By keeping the difference between the in-plane average refractive index and the in-plane normal refractive index within the above-mentioned range, it is possible to maintain the film's properties, suppress poor appearance due to heat during the bonding process, and impart excellent shape conformance to even complex shapes.

The method for achieving a difference between the in-plane average refractive index and the perpendicular refractive index of the surface of 0.01 to 0.30 is not particularly limited, but an example is a method in which a small amount of crystalline polyethylene terephthalate is blended into a thermoplastic resin whose difference between the in-plane average refractive index and the perpendicular refractive index of the surface is less than 0.01.

The film used in the method for producing a laminate of the present invention preferably has an in-plane retardation of 1,500 nm or more and 10,000 nm or less. If the in-plane retardation is less than 1,500 nm, the film may appear discolored when used as a window film, especially when wearing polarized sunglasses. Furthermore, if the in-plane retardation is greater than 10,000 nm, the film may be oriented too strongly in one direction, impairing handleability. By setting the in-plane retardation within the above range, both appearance and handleability can be achieved when used as a window film. A retardation of 1,500 nm or more and 3,000 nm or less is particularly preferred. In this case, not only is the appearance and handleability particularly excellent, but high transparency is also easily maintained. The retardation can be achieved by adjusting the stretching conditions when stretching the film.

The thickness of the film used in the method for producing a bonded body of the present invention is preferably 20 μm to 300 μm. If the film thickness is thinner than 20 μm, the film may be difficult to produce and provide, while if the film thickness is thicker than 300 μm, the film may become stiff and difficult to handle. By keeping the film thickness within the above range, not only is the film easier to produce, but the film's handleability is improved, making the application process, which involves heating, easier to carry out.

Next, a preferred manufacturing method for obtaining a biaxially oriented film suitable for use in the manufacturing method of the laminate of the present invention will be explained below using the example of a method in which two types of thermoplastic resins are sequentially biaxially stretched, but the present invention should not be construed as being limited to this example.

First, the thermoplastic resins that make up each thermoplastic resin layer of the film are prepared in the form of pellets or the like. When alloying amorphous polyester and crystalline polyester, it is preferable to prepare pellets that have been kneaded in advance using a twin-screw extruder or similar. The dispersion state of the crystalline polyester can be controlled by selecting the screw of the twin-screw extruder, controlling the discharge rate, screw rotation speed, and kneading temperature, and can also be achieved by adding a compatibilizer such as a polyester elastomer. By preparing pellets that have been kneaded in advance using a twin-screw extruder or similar, it is possible to control the dispersion state and domain size of the crystalline polyester in the amorphous polyester.

The pellets are then dried in hot air or under vacuum as needed and then fed into separate extruders. The pellets are heated and melted in each extruder to a temperature above the melting point or between 250 and 330°C. The resin extrusion rate is then uniformized using a gear pump or similar, and foreign matter and denatured resin are removed from the molten resin using a filter or similar. The resin is then formed into a sheet using a die and discharged. It is then cooled and solidified on a cooling body such as a casting drum to obtain an unoriented sheet. In this process, it is preferable to use a wire-, tape-, needle-, or knife-shaped electrode to electrostatically press the molten sheet against a cooling body such as a casting drum, thereby rapidly solidifying it. Other preferable methods for pressing the molten sheet against the cooling body include blowing air from a slit-, spot-, or planar device to press the molten sheet against the cooling body, or using nip rolls to press the molten sheet against the cooling body. The surface temperature of the casting drum is preferably between 20 and 50°C.

Furthermore, when producing a sheet consisting of multiple thermoplastic resin layers, the multiple resins are fed through different channels using the same number of extruders as the number of resin types, and then fed into a multi-layer lamination device. For two types of thermoplastic resin layers, two extruders are used. While a multi-manifold die, feed block, static mixer, etc. can be used as the multi-layer lamination device, it is preferable to use a feed block containing at least two separate components with multiple fine slits, particularly for efficiently achieving the desired layer structure in the film used in the first invention. The use of such a feed block prevents the device from becoming excessively large, suppresses the generation of foreign matter due to thermal degradation, and enables high-precision lamination even when the number of layers is extremely large. Furthermore, lamination accuracy in the width direction is significantly improved compared to conventional technology, and it is also easy to form an arbitrary layer thickness structure. This device allows the thickness of each layer to be adjusted by the shape (length and width) of the slits, making it easy to achieve an arbitrary layer thickness. The molten multi-layer laminate formed in this manner with the desired layer structure is then guided into the die, and an unoriented sheet is obtained as described above.

Next, the resulting unoriented sheet is biaxially stretched in the longitudinal and width directions. Here, stretching in the longitudinal direction refers to uniaxial stretching to impart longitudinal molecular orientation to the sheet, and is typically achieved by varying the peripheral speed of the longitudinal stretching machine rolls. This stretching can be performed in a single stage or in multiple stages using multiple pairs of rolls. The stretching ratio varies depending on the type of resin, but is typically 2 to 10 times. For example, when using polyethylene terephthalate or polyethylene naphthalate, which are thermoplastic resins that form the crystalline thermoplastic resin layer preferably used in the film of the first invention, a ratio of 2 to 7 times is particularly preferred. If the stretching ratio is excessively high during the longitudinal stretching process, strong orientation can occur, resulting in neckdown in the width direction, which can prevent the sheet from achieving sufficient width. This can also result in significant thickness unevenness in the longitudinal and/or width directions after width stretching. Furthermore, the stretching temperature is preferably set within the range of the glass transition temperature of the thermoplastic resin layer with the highest glass transition temperature among the thermoplastic resin layers constituting the sheet to the glass transition temperature + 100°C.

The uniaxially stretched sheet is then stretched in the width direction. Prior to this, if necessary, surface treatments such as corona treatment, flame treatment, and plasma treatment may be performed, followed by the application of an adhesion layer by in-line coating to provide properties such as slipperiness, adhesion, and antistatic properties. In the in-line coating process, the adhesion layer may be applied to one side of the film, or to both sides of the sheet simultaneously or sequentially. Width-direction stretching refers to stretching to impart width-direction orientation to the sheet. This is typically achieved by using a tenter to hold both widthwise edges of the sheet with clips and conveying the sheet while increasing the distance between the opposing clips. The stretching ratio varies depending on the type of resin, but is typically preferably 2 to 10 times. For example, when using polyethylene terephthalate or polyethylene naphthalate, which are thermoplastic resins that form the crystalline thermoplastic resin layer preferably used in the film of the present invention, a stretching ratio of 2 to 7 times is particularly preferred. The stretching temperature is preferably between the glass transition temperature of the resin with the highest glass transition temperature among the resins constituting the sheet and the glass transition temperature + 120°C.

The biaxially stretched film is then heat-treated in a tenter at a temperature equal to or higher than the stretching temperature but lower than the melting point of the thermoplastic resin layer with the highest melting point among the thermoplastic resin layers constituting the film, preferably at a temperature equal to or higher than the stretching temperature but lower than the melting point of the thermoplastic resin layer with the highest melting point among the thermoplastic resin layers constituting the film - 30°C. The film is then uniformly and slowly cooled, then cooled to room temperature and wound up. If necessary, a relaxation treatment may be performed in the longitudinal and/or transverse directions between the heat treatment and the slowly cooling to impart thermal dimensional stability.

Here, in the manufacturing method for making the film used in the manufacturing method of the laminate of the present invention such that 0.7≦ΔS ₁₅₀ ≦10.0, it is preferable that the heat treatment temperature after widthwise stretching is below the melting point of at least one thermoplastic resin and above the melting point of at least one of the remaining thermoplastic resins. In this case, one thermoplastic resin maintains a high orientation state, while the orientation of the other thermoplastic resin is relaxed, so that it is easy to create a refractive index difference between these resins, and it is also possible to impart higher heat shrinkage behavior only in the width direction while maintaining the orientation. For example, in the case of having two thermoplastic resin layers (A1 layer, B1 layer) with different main components, where the A1 layer is made of a crystalline polyester (crystalline polyester A1) and the B1 layer is made of an amorphous polyester and a crystalline polyester (crystalline polyester B1) different from the crystalline polyester A1, the heat treatment temperature is preferably below the melting points of the crystalline polyester A1 and the crystalline polyester B1. In this case, since the orientation of the crystalline polyester A1 as well as the orientation of the crystalline polyester B1 is maintained, more preferable heat shrinkage behavior can be imparted.

It is also preferable to perform a relaxation treatment in the width direction between the heat treatment and the gradual cooling, but since relaxation treatment is usually performed to suppress thermal shrinkage behavior (reduce the shrinkage rate), it is also preferable not to perform the relaxation treatment in the width direction to obtain a film for use in the first invention, and the preferred degree of relaxation treatment is a ratio of the relaxation treatment to the film width before the relaxation treatment of 0% to 5%. Although it depends on the type of thermoplastic resin used, for example, in the case of polyethylene terephthalate and an amorphous polyester that is completely melted in the heat treatment step, a film that satisfies 0.7≦ΔS ₁₅₀ ≦10.0 can be obtained with a ratio of the relaxation treatment to the film width before the relaxation treatment in the range of about 0% to 5%.

It is also preferable to perform additional stretching in the width direction between the heat treatment and the annealing. By performing additional stretching, the orientation in the width direction is further strengthened, making it easy to increase the shrinkage rate in the width direction only, and a film satisfying 0.7≦ΔS ₁₅₀ ≦10.0 can be easily obtained. The ratio of additional stretching is preferably in the range of about 2% to 5% of the film width before additional stretching.

The film used in the method for producing a bonded body of the present invention may further have a functional layer. Here, a functional layer refers to a layer having a function not present in the film used in the first invention, such as an easy-adhesion layer, hard coat layer, abrasion-resistant layer, scratch-resistant layer, anti-reflection layer, color correction layer, UV absorbing layer, heat absorbing layer, weather-resistant layer, printing layer, gas barrier layer, adhesive layer, conductive layer, or protective layer. The functional layer may have only one of the above-mentioned functions, or may have multiple functions. The functional layer may also consist of one layer or two or more layers. The same functional layer may be present on both sides of the film, or functional layers with different functions may be present on each side.

The functional layer of the film used in the method for manufacturing a bonded body of the present invention preferably has adhesive properties. Adhesive properties refer to the ability to adhere to other materials. Methods for imparting adhesive properties to the functional layer are not particularly limited, but examples include applying adhesives to the functional layer, such as vinyl acetate resins, vinyl chloride-vinyl acetate copolymers, ethylene-vinyl acetate copolymers, polyvinyl alcohol, polyvinyl butyral, polyvinyl acetal, polyvinyl ether, nitrile rubbers, styrene-butadiene rubbers, natural rubbers, chloroprene rubbers, polyamides, epoxy resins, polyurethanes, acrylic resins, cellulose, polyvinyl chloride, polyacrylic esters, and polyisobutylene. These components may be used alone or in combination. If necessary, adhesive modifiers, plasticizers, heat stabilizers, antioxidants, UV absorbers, antistatic agents, lubricants, colorants, crosslinkers, and the like may also be added. These adhesives may be in liquid, gel, block, powder, sheet, or other forms before processing.

Methods for providing an adhesive functional layer to the film used in the manufacturing method of the bonded body of the present invention include coating the film with the aforementioned liquid or gel adhesive, or transferring a sheet-like adhesive to the film.

The functional layer of the film used in the manufacturing method of the bonded body of the present invention preferably has heat ray absorption properties. Heat ray absorption refers to the ability to absorb light rays mainly in the near-infrared to far-infrared region with wavelengths exceeding 700 nm. The presence of such a functional layer can further enhance heat-shielding performance.

There are no particular limitations on the method for imparting heat ray absorption to the functional layer. For example, the functional layer may contain a heat ray absorbing material. Examples of applicable heat ray absorbing materials include lanthanum-based particles, antimony-based particles, indium-based particles, tin-based particles, and tungsten-based particles. These are preferred from the perspective of ensuring transparency, even though they have low light absorption in the visible light range. In general, lanthanum-based particles and tungsten-based particles have particularly high absorption performance in the wavelength range of 700 to 1500 nm, while antimony-based particles, indium-based particles, and tin-based particles have particularly high absorption performance in the wavelength range of 1500 nm and beyond. These heat ray absorbing materials may be used alone or in combination, and are preferably used in combination with the aforementioned adhesive.

Resins suitable for the heat-absorbing functional layer are preferably selected from acrylic resins, urethane resins, polyester resins, silanols, etc., and the type is not particularly limited, and these can be used alone or in combination. Taking acrylic resins as an example, it is preferable to use acrylic resins obtained using monomers such as methacrylic acid, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-hexyl methacrylate, lauryl methacrylate, 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate, acrylic acid, methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, n-hexyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, glycidyl acrylate, glycidyl methacrylate, 4-hydroxybutyl acrylate glycidyl ether, 4-hydroxybutyl methacrylate glycidyl ether, phenylglycidyl acrylate, epoxy acrylate, epoxy methacrylate, and dipentaerythritol hexaacrylate (these monomers may be used alone or in combination).

The resin forming the heat-absorbing functional layer and its precursor mixture are preferably cured using an initiator, curing agent, or catalyst, as this accelerates curing. Initiators that can initiate or accelerate polymerization, condensation, or crosslinking reactions, such as anionic, cationic, or radical reactions, are preferred. Various initiators, curing agents, and catalysts can be used. Each initiator, curing agent, and catalyst may be used alone, or multiple initiators, curing agents, and catalysts may be used simultaneously. Acidic catalysts, thermal polymerization initiators, and photopolymerization initiators may also be used in combination, with photopolymerization initiators being preferred.

Examples of acidic catalysts include aqueous hydrochloric acid, formic acid, and acetic acid. Examples of thermal polymerization initiators include peroxides and azo compounds. Examples of photopolymerization initiators include alkylphenone compounds, sulfur-containing compounds, acylphosphine oxide compounds, and amine compounds. From the perspective of curability, alkylphenone compounds are preferred as photopolymerization initiators. Specific examples of alkylphenone compounds include 1-hydroxycyclohexylphenylketone, 2.2-dimethoxy-1.2-diphenylethane-1-one, 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1-(4-phenyl)-1-butane, and 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-(4-phenyl)-1-butane. , 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-1-butane, 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(4-morpholinyl)phenyl]-1-butane, 1-cyclohexyl-phenyl ketone, 2-methyl-1-phenylpropan-1-one, 1-[4-(2-ethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one, and the like.

Methods for providing a heat ray absorbing functional layer to the film used in the manufacturing method of the laminate of the present invention include applying a mixture that forms a heat ray absorbing functional layer to the film, or transferring a heat ray absorbing sheet formed on another film to the film.

The functional layer of the film used in the method for producing a bonded body of the present invention preferably has weather resistance. Weather resistance means durability against natural environmental factors such as ultraviolet rays, wind and rain, and temperature changes. By having a functional layer of this nature, deterioration of the film can be suppressed when applied to the outside of a building or car window, for example.

There are no particular limitations on the method for imparting weather resistance to the functional layer, but an example is to incorporate an ultraviolet absorber. Examples of ultraviolet absorbers include benzophenone-based compounds, triazine-based compounds, and benzotriazole-based compounds, and it is preferable to incorporate at least one selected from these. Specific examples of benzophenone-based compounds include salicylate-based ultraviolet absorbers such as phenyl salicylate, 4-t-butylphenyl salicylate, 2,4-di-t-butylphenyl-3,5'-di-t-butyl-4'-hydroxylbenzoate, and 4-t-octylphenyl salicylate; 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid, 2-hydroxy-4-n-octoxybenzophenone, and 2-hydroxy-4-n-dodecyloxybenzophenone. Examples include benzophenone, 2-hydroxy-4-benzyloxybenzophenone, bis(5-benzoyl-4-hydroxy-2-methoxyphenyl)methane, 2,2'-dihydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2,2',4,4'-tetrahydroxybenzophenone, 4-dodecyloxy-2-hydroxybenzophenone, 2-hydroxy-4-methoxy-2'-carboxybenzophenone, and 2-hydroxy-4-(2-methacryloyloxyethoxy)benzophenone.

Examples of triazine compounds include 2-[4-[(2-hydroxy-3-dodecyloxypropyl)oxy]-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, 2-[4-(2-hydroxy-3-tridecyloxypropyl)oxy]-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, 2-[4-[(2-hydroxy-3-(2'-ethyl)hexyl)oxy]-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, 2,4-bis(2-hydroxy-4-butyloxyphenyl)-6-(2,4-bis-butyloxyphenyl)-1,3,5-triazine, and 2-(2-hydroxy-4-[1-octyloxycarbonylethoxy] Examples of hydroxyphenyltriazine-based ultraviolet absorbers include ([(4-phenylphenyl)-4,6-bis(4-phenylphenyl)-1,3,5-triazine), 2,2',4,4'-tetrahydroxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2,4-dihydroxybenzophenone, 2-hydroxy-4-acetoxyethoxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2-hydroxy-4-n-octoxybenzophenone, and 2,2'-dihydroxy-4,4'-dimethoxy-5,5'-disulfobenzophenone disodium salt.

Benzotriazole compounds include 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-[2'-hydroxy-3',5'-bis(α,α-dimethylbenzyl)phenyl]benzotriazole, 2-(2'-hydroxy-3',5'-di-t-butylphenyl)benzotriazole, and 2-(2'-hydroxy-3'-t-butyl-5'-methylphenyl)-5-chlorobenzotriazole. , 2-(2'-hydroxy-3',5'-di-t-butylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3',5'-di-t-amyl)benzotriazole, 2-(2'-hydroxy-5'-t-octylphenyl)benzotriazole, 2,2'-methylenebis[4-(1,1,3,3-tetramethylbutyl)-6-(2N-benzotriazole-2-yl)phenol], etc.

These may be used alone or in combination of two or more. Among these, hydroxyphenyltriazine-based ultraviolet absorbers are preferred because the ultraviolet absorbers themselves are stable against ultraviolet light and heat and have excellent absorption capabilities.

Commercially available UV absorbers include Tinuvin 326, 384-2, PS, 900, 400, 460, 477, and 479 (manufactured by BASF), Adekastab LA-29, 31, 36, 46, and 1413 (manufactured by ADEKA Corporation), and Hostavin ARO8, 3041, and VSU (manufactured by Clariant).

The resins suitable for the weather-resistant functional layer are the same as those suitable for the heat-absorbing functional layer described above, and the method for forming the functional layer is also the same.

<Substrate>
The method for manufacturing a bonded body of the present invention includes a bonding step of bonding a film onto a substrate. In the present invention, the substrate refers to a plate-like body to which a film can be bonded. The substrate must have a curved surface shape in order to achieve a desired maximum curvature in the X direction of the film after the bonding step described below. The material of the substrate is not particularly limited, but examples include glass, resin, metal, and ceramic. Examples of resins include acrylic resins such as polycarbonate, cyclic polyolefin, polyarylate, polyethylene terephthalate, and polymethyl methacrylate, ABS, and triacetyl cellulose. These components may be used alone or in combination. The glass is not particularly limited, and commonly used transparent glass can be used. Specific examples include clear glass, float glass, polished glass, figured glass, wired glass, lined glass, infrared-absorbing glass, infrared-reflecting glass, and green glass. The substrate is preferably transparent, and its thickness is preferably 0.5 mm to 5.0 mm.

In the lamination process of laminating a film onto a substrate, when the film is to be laminated to form a curved surface, the most preferred method is to laminate a film having an adhesive functional layer on at least one side to a curved substrate while applying a temperature of 150°C or higher to form the film. From this perspective, it is preferable that the substrate be glass.

The substrate used in the method for manufacturing a bonded body of the present invention may have a single curved shape, curved in only one of the left-right or up-down directions, or a compound curved shape, curved in both the left-right and up-down directions. The curvatures in the left-right and up-down directions may or may not be the same. The substrate may have one or more curved surfaces. The substrate of the present invention has a curved surface, and all points on this curved surface have a maximum curvature in the direction of one tangent vector (first tangent vector) of two tangent vectors that are tangent to the curved surface and perpendicular to each other, and a minimum curvature in the direction of the other tangent vector (second tangent vector).

The relationship between each vector and curvature mentioned above will be explained in detail for one curved surface. Let S1 be one surface of the substrate, a point on S1 be point P, and let Sn be the plane containing the unit normal vector n and unit tangent vector x at point P. S1 cut by Sn describes a curve c. Furthermore, if the curvature of curve c at point P is κ, then the unit tangent vector x1 where curvature κ is the maximum value κ1 and the unit tangent vector x2 where curvature κ is the minimum value κ2 are mutually orthogonal (according to Euler's theorem; the theorem of identification, where θ is the angle between x and x1, κ = κ1 cos2θ + κ2 sin2θ). Note that the maximum value κ1 of curvature κ is the maximum curvature, and the minimum value κ2 is the minimum curvature. Furthermore, of all points on the substrate, the point with the largest maximum curvature κ1 is defined as point Pmax, the maximum curvature at point Pmax is defined as κA, the direction of the unit tangent vector that results in κA is defined as direction A, the minimum curvature is defined as κB, and the direction of the unit tangent vector that results in κB is defined as direction B. Note that, as mentioned above, direction A and direction B are orthogonal.

When the substrate has a single curved shape, it has a point where the minimum curvature κ2 is 0. When the substrate has a compound curved shape, with a curved surface having non-uniform curvatures in the left-right and up-down directions, it has a point where the maximum curvature κ1 and minimum curvature κ2 are different. When the substrate has a compound curved shape, with a curved surface having identical curvatures in the left-right and up-down directions, it has a point where the maximum curvature κ1 and minimum curvature κ2 are substantially the same. The substrate used in the first invention preferably has a point where the maximum curvature κ1 and minimum curvature κ2 are different, and more preferably has a point where the minimum curvature κ2 is 0.

<Attachment process>
The method for producing a bonded body of the present invention includes a bonding step of bonding a film onto a substrate, and the maximum curvature of the film in the X direction after the bonding step is 0.0001 or more and 0.1 or less. Regardless of the shape of the substrate, by making the film have a curved shape at least in the X direction, i.e., in the maximum shrinkage direction, it becomes easy to impart excellent shape followability even to complex shapes.

In the method for producing a bonded body of the present invention, the bonding step of bonding a film to a substrate is not particularly limited as long as it allows the substrate and film to be bonded together. Examples include a step of applying a pressure-sensitive adhesive or adhesive to a substrate by coating or laminating the substrate, and then bonding the film, or a step of applying a pressure-sensitive adhesive or adhesive to a film by coating or laminating the film, and then bonding the film to the substrate. Furthermore, methods for creating a curved shape include subjecting a substrate with a curve to the aforementioned bonding step, or forming a curved surface after the aforementioned bonding step. Furthermore, methods that involve heating when imparting a curved shape to a film are more preferred.

As an example of the application process, a curved glass substrate is used, and a film having an adhesive layer on one side is applied to the curved inner surface of the glass. However, the application process is not limited to this procedure. First, a working solution is prepared by dissolving a surfactant in water. Distilled water, ion-exchanged water, or tap water can be used. Surfactants that can be used include ester-type surfactants such as glycerin fatty acid esters, sorbitan fatty acid esters, and sucrose fatty acid esters; ether-type surfactants such as alkyl polyethylene glycols and polyoxyethylene alkylphenyl ethers; and nonionic surfactants such as alkyl glycosides. The surfactant concentration in the working solution can be, for example, approximately 0.01% by mass or more and approximately 5% by mass or less. By keeping the surfactant content within this range, the wettability of the working solution to the glass surface and evaporation time can be easily adjusted.

Next, spray the application liquid onto the curved outer surface of the glass (the side opposite to the surface to which the film will be applied), and attach the adhesive-free side of a film cut to a sufficient size to the curved outer surface of the glass. At this time, the surface tension of the application liquid will cause the film to adhere to the curved outer surface of the glass. Adjust the position and size of the film as needed. Use a heat gun or similar device to apply hot air to areas of the film that are not in contact with the glass, particularly curved sections of the glass, to shrink those areas and bring them into contact with the glass surface. Spray the application liquid again between the film and the glass, and use a squeegee to adhere the film to the curved outer surface of the glass. If there are any areas where the film is not adhering sufficiently, use a heat gun or similar device to apply hot air again to shrink the film until it adheres tightly to the curved outer surface of the glass. Once the entire film is in contact with the curved outer surface of the glass, mark the position on the film as appropriate and then remove it from the glass.

Then, spray the application liquid onto the curved inner surface of the glass (the surface to which the film will be applied), and also onto the surface of the adhesive layer of the film. The film is applied to the curved inner surface of the glass. A squeegee is used to scrape out the application liquid between the film and the curved inner surface of the glass towards the outer periphery of the film, while pressing the film against the glass to adhere the film to the curved inner surface of the glass.

In the present invention, the maximum curvature of the film in the X direction after the lamination step being 0.0001 or more and 0.1 or less means that the film is laminated such that the X direction of the film, i.e., the maximum shrinkage direction, is at least the direction in which the curved surface is formed. One example of such an embodiment is a method of laminating a film to a substrate that has a direction in which the maximum curvature is 0.0001 or more and 0.1 or less, so that the X direction overlaps with that direction.

Furthermore, in the method for producing a bonded body of the present invention, when the direction in which the curvature of the bonded body is greatest is defined as the A direction, the angle between the X direction and the A direction is preferably 0° or more and 30° or less. Here, the angle between the X direction and the A direction is the angle when viewed from the direction of the unit normal vector at point Pmax where the curvature of the bonded body is greatest. A 0° angle between the X direction and the A direction means that the direction of maximum shrinkage of the film is aligned with the direction of maximum curvature of the substrate. If the angle between the X direction and the A direction exceeds 30°, the direction in which the shrinkage rate of the film is small will be the direction in which the curvature of the substrate is greatest, resulting in insufficient conformance to the curved surface shape and possibly resulting in poor appearance of the resulting bonded body. By setting the angle between the X direction and the A direction within the above range, the film can efficiently conform to various shapes, such as substrates with different curvatures in the left-right and up-down directions or substrates with multiple curves, and poor appearance of the entire substrate can be suppressed.

It is also preferable that the film used in the manufacturing method of the bonded body of the present invention satisfies 0.1≦S _150X < 2.5 and −0.6≦S _150Y < 1.8. When S _150X is smaller than 0.1 and S _150Y is smaller than −0.6, the film does not shrink in any direction, and therefore, depending on the size of the substrate, it may be difficult to suppress poor appearance on a substrate having a curved surface.

The substrate used in the method for producing a bonded body of the present invention preferably has a maximum curvature κA in the A direction of 0.0001 or more and 0.0050 or less. When the substrate is in this form, the degree of curvature is gentle. Furthermore, the reciprocal of curvature is the radius of curvature. When the radius of curvature of the maximum curvature κA of the bonded body is R _A and the radius of curvature of the minimum curvature κB perpendicular to the maximum curvature κA is R _B , if κA is 0.0001 or more and 0.0050 or less, R _A is 500 to 10,000 mm, and the difference between R _A and R _B is preferably 4,500 mm or more. That is, R _B is preferably approximately 5,000 to 12,000 mm. The larger the difference between R _A and R _B , i.e., the greater the shape anisotropy, the more efficiently the effect of the difference in the shrinkage rate of the film is exerted, and poor appearance is suppressed, which is preferable. For the same reason, it is also preferable that the substrate has a κB of 0 (i.e., a single-bend shape). The κA of the bonded body can be adjusted by the κA of the substrate.

In the method for producing a bonded body of the present invention, when the film satisfies 0.1≦S _150X < 2.5 and −0.6≦S _150Y < 1.8, it is more preferable that the bonded body has a maximum curvature κA in the A direction of 0.0001 or more and 0.0050 or less, since this reduces poor appearance due to insufficient or excessive shrinkage of the film.

The film used in the method for producing a laminate of the present invention may satisfy 4.0≦S _150X ≦20.0 and 3.3≦S _150Y ≦19.7. When S _150X is less than 4.0 and S _150Y is less than 3.3, the film does not shrink in any direction, making it difficult to suppress poor appearance on a curved substrate. When S _150X is 20.0 or less and S _150Y is 19.7 or less, sufficient heat treatment during film production ensures toughness, improving handleability and reducing poor appearance due to wrinkles caused by excessive shrinkage.

The bonded body obtained by the bonded body manufacturing method of the present invention preferably has a maximum curvature κA in the A direction greater than 0.0050 and less than 0.1. When the substrate has such an embodiment, it has a relatively steeply curved surface. Furthermore, when the radius of curvature of the maximum curvature κA of the bonded body is R _A and the radius of curvature of the minimum curvature κB perpendicular to the maximum curvature κA is R _B , if κA is greater than 0.0050 and less than 0.1, R _A is 10 to 200 mm, and the difference between R _A and R _B is preferably 4,500 mm or more. That is, R _B is preferably approximately 5,000 to 12,000 mm. The greater the difference between R _A and R _B , i.e., the greater the shape anisotropy, the more efficiently the effect of the difference in the shrinkage rates of the films is exerted, and poor appearance is suppressed, which is preferable. For the same reason, it is also preferable that the substrate has a κB of 0 (i.e., a single-bend shape). The κA of the bonded body can be adjusted by the κA of the substrate.

In the manufacturing method of the bonded body of the present invention, it is more preferable that the film satisfies 4.0≦S _150X ≦20.0 and 3.3≦S _150Y ≦19.7, and the substrate has a maximum curvature κA in the A direction that is greater than 0.0050 and less than 0.1, since this can prevent insufficient shrinkage of the film relative to the shape, resulting in poor appearance, and conversely, prevent excessive shrinkage, resulting in wrinkles in the film, resulting in poor appearance.

In the present invention, when the thickness of the film is D and the layer groups are divided into two at a position D/2 from one surface, the layer group with the smallest average layer thickness is designated as layer group A, and the layer group with the thickest average layer thickness is designated as layer group B, it is preferable to position the film in the attachment process so that layer group A is on the inner curved surface side. Here, the average layer thickness refers to the average value of the layer thicknesses of each layer within a layer group, and a layer group refers to a group of layers that are part of a structure in which thermoplastic resin layers are regularly laminated.

The film used in the manufacturing method of the laminate of the present invention preferably has a layer thickness distribution in which the layer thickness of each layer changes continuously. Therefore, if the film is divided in half at the halfway point, one half will have a thicker average layer thickness and the other half will have a thinner average layer thickness. Furthermore, when the film is applied to a substrate with a curved surface, the curvature of the inner curved surface in the thickness direction of the film will be greater by the thickness of the film.

In conventional technology, there are examples of applying a film laminated with a thermoplastic resin layer to a curved surface, but the orientation of the film's surface has not been given much consideration. As a result, when the film is applied to a curved surface, poor appearance sometimes occurs and sometimes does not, and it has not been possible to consistently suppress poor appearance.

As a result of extensive research, the inventors discovered that, as described above, it is important to arrange the film so that the layer group A with the thinner average layer thickness is on the inner curved surface side. A thin average layer thickness means that each layer is thin, but thinner layers have higher flexibility and are easier to conform to complex shapes and unevenness. Therefore, by arranging the layer with the thinner average layer thickness on the inner curved surface side (the side with greater curvature), it is possible to impart excellent shape conformability to complex shapes, and moreover, to achieve this stably.

The bonded article obtained by the present invention is suitable for windows in buildings and automobiles because it is glass or the like with a curved surface that has few appearance defects. It is particularly suitable for windows that require high design quality, aesthetics, visibility from the inside, and interior heat insulation (comfort). It is also suitable as an information display component because it can prevent temperature increases in the devices inside the screen while ensuring visibility of the screen. In other words, the windows and information display devices of the present invention comprise a bonded article obtained by the bonded article manufacturing method of the present invention.

Next, the oriented film of the present invention will be described. The oriented film of the present invention has a configuration in which two or more thermoplastic resin layers having different main components are regularly laminated in a total of 51 to 2001 layers, and the direction in which the shrinkage rate S ₁₅₀ (%) at 150 ° C is the largest is the X direction, the direction perpendicular to the X direction in the film plane is the Y direction, the shrinkage rate in the X direction at 150 ° C is S _150X (%), the shrinkage rate in the Y direction at 150 ° C is S _150Y (%), and S _150X -S _150Y is ΔS ₁₅₀ , where 0.7≦ΔS ₁₅₀ ≦10.0 is satisfied. Such an oriented film can be obtained in the same manner as the film used in the manufacturing method of the bonded body of the present invention described above. Furthermore, the respective properties described for the film used in the manufacturing method of the bonded body of the present invention can also be similarly applied to the oriented film of the present invention.

The film of the present invention will be described below with specific examples. It should be noted that even if a thermoplastic resin other than the thermoplastic resins specifically exemplified below is used, the film of the present invention can be obtained in the same manner as above, provided that the description of this specification, including the examples below, is taken into consideration.

[Methods for measuring physical properties and evaluating effects]
The methods for evaluating the physical properties and the effects are as follows.

(1) Shrinkage ratio S ₁₅₀ , ΔS ₁₅₀
Measurements were performed under the following conditions using a Seiko Instruments Inc. heat, stress, and strain measurement device (TMA/SS6000). Samples were cut out in a plane parallel to the film surface, in the longitudinal direction, and in each direction rotated 180° from there at 5° intervals in an in-plane direction parallel to the film surface. At least one data point was obtained per 1°C, and the shrinkage at each temperature was calculated using the following equation (3) to obtain a thermal shrinkage curve. Measurements were performed three times in each direction, and the direction with the largest shrinkage at 150°C (S ₁₅₀ %) was defined as the X direction, and the direction perpendicular to the X direction in the film plane was defined as the Y direction. The shrinkage in the X direction at 150°C was defined as S _150X (%), and the shrinkage in the Y direction at 150°C was defined as S _150Y (%), and ΔS 150 was calculated as ΔS ₁₅₀ = S _150X - S _150Y .
Sample size: width 4 mm, length 15 mm
Temperature range: 25 to 200°C
Temperature rise rate: 10°C/min Measurement load: 19.8N
Temperature 23°C, relative humidity 65%, in the atmosphere Formula 3: Shrinkage ratio at a temperature of 150°C S ₁₅₀ = (L(25) - L(150)) / L(25) × 100
L(T): sample length at T°C.

(2) Number of Layers, Layer Thickness, and Average Layer Thickness The number of layers and layer thickness of the film were determined by observation with a transmission electron microscope (TEM) of a sample thinned using an ultramicrotome. Specifically, a transmission electron microscope JEM-1400 Plus (manufactured by JEOL Ltd.) was used to observe the cross section of the laminated film at an acceleration voltage of 100 kV, and the number of layers was determined by acquiring a cross-sectional image. To obtain a large contrast difference between each layer, a staining technique using an electronic stain (e.g., _RuO4 ) was used. Furthermore, depending on the thickness of each layer, observation was performed at a direct magnification of 40,000x when the thin film layer thickness was less than 100 nm, a direct magnification of 20,000x when the thin film layer thickness was 100 nm or more but less than 500 nm, and a direct magnification of 1,000x to 10,000x when the thin film layer thickness was 500 nm or more. The number of layers and layer thickness were determined based on the contrast difference in the obtained image. The average layer thickness of the corresponding location was calculated from the determined layer thickness of each layer.

(3) Layer interface (contrast difference)
The cross-sectional image obtained by transmission electron microscope observation (2) was converted to a compressed image file (JPEG) format, and position-brightness data was obtained by line profiling along the thickness direction of the laminate film using ImagePro-10 (sold by Hakuto Co., Ltd.). Then, using spreadsheet software (Microsoft Excel (registered trademark) 2016), the relationship between position and brightness was plotted, and a five-point moving average was applied to the resulting profile. The averaging process was performed by averaging brightness at five consecutive measurement positions, changing the position one point at a time, and repeatedly performing the same calculation to obtain an averaged position-brightness profile. In the obtained averaged position-brightness profile, the positions surrounded by inflection points where the slope changes from positive to negative or negative to positive were determined to be one layer. For each layer obtained by this method, position-brightness data was then obtained in the planar direction of the laminate film (the direction perpendicular to the thickness direction). After calculating the average and standard deviation of the brightness obtained for each layer, if the difference between the average brightness values of two adjacent layers was greater than either of the standard deviations of the brightness values of the adjacent thermoplastic resin layers, the two adjacent layers were determined to be different.

(4) Differential scanning calorimetry (DSC)
A differential scanning calorimeter EXSTAR DSC6220 manufactured by Hitachi High-Technologies Corporation was used. Measurements and temperature readings were performed in accordance with JIS-K-7122 (1987). Specifically, approximately 5 mg of sample was placed on an aluminum pan and heated from 25°C to 300°C at a rate of 10°C/min. The intersection of the baseline when heated from room temperature and the tangent to the inflection point of the step transition portion was taken as the glass transition temperature Tg (°C). After heating, the sample was rapidly cooled with liquid nitrogen, and the endothermic peak observed on the highest temperature side when heated again under the same conditions was taken as the melting point (°C). The integrated value from the baseline within the range of the melting point ± 20°C at this time was taken as the enthalpy of fusion (J/g).

(5) Reflectance A sample cut to 5 cm x 5 cm was subjected to reflectance measurement using a Hitachi spectrophotometer (U-4100 Spectrophotometer) with an integrating sphere attached to the basic configuration. In this measurement, the measurement was performed using an aluminum oxide secondary white plate attached to the device as a reference. In the reflectance measurement, the sample was placed behind the integrating sphere with its longitudinal direction facing up and down, and the reflectance was measured under the following conditions to confirm the presence or absence of a reflection band, calculate the average reflectance in the wavelength band from 400 nm to 700 nm, and calculate the average reflectance in the wavelength band from 900 nm to 1200 nm.
<Measurement conditions>
Slit: 2 nm (visible) / automatic control (infrared)
Gain: 2
Scanning speed: 600 nm/min Starting wavelength: 2600 nm
End wavelength: 240 nm
Sampling interval: 1 nm
Incident angle: 10°.

(6) Preparation of the laminate First, a film having an adhesive layer as the functional layer A was obtained as follows. 83.3 parts by weight of 2-ethylhexyl acrylate, 14.7 parts by weight of N,N-dimethylacrylamide, 2.0 parts by weight of 2-hydroxyethyl acrylate, 185.7 parts by weight of ethyl acetate was mixed to prepare a monomer mixture, and 0.2 parts by weight of V-65 was added as an initiator. The mixture was reacted for 24 hours at 50 ° C. under a nitrogen atmosphere to obtain a 35% ethyl acetate solution of (meth)acrylic copolymer. Next, 100 parts by weight of the obtained (meth)acrylic copolymer solution was mixed with 2.19 parts by weight of Tinuvin (trademark) 477 and 0.08 parts by weight of Coronate (trademark) 2203, and applied to one side of the films obtained in Examples 1 to 22 and Reference Examples 1 to 3 so that the thickness after drying was 20 μm, and then dried at 90 ° C. for 5 minutes to obtain a film having an adhesive layer. In Examples 26, 27, 42, and 43, functional layer B and functional layer C were laminated on one side of the film obtained in Examples 1 and 12, and then functional layer A was laminated on the opposite side. The films were 300 mm square. Next, a working solution was prepared by dissolving 0.05% by mass of glycerin fatty acid ester in distilled water. The curved glass substrates 1 to 4 were used as substrates, and the working solution was sprayed on the side opposite to the side to which the film was to be applied, and the side of the film without the adhesive layer was attached. Then, hot air was applied using a heat gun to the curved portion of the film that was not in contact with the glass, bringing it into contact with the glass surface, and the film was removed from the glass. A squeegee was used to bring the film into contact with the glass. The working solution was then sprayed on the side of the substrate to which the film was to be applied, and also on the surface of the adhesive layer of the film, and the film was attached to the side of the substrate to which the film was to be applied. The working solution between the film and the curved inner surface of the glass was scraped out using a squeegee toward the periphery of the film, while the film was pressed against the glass, to obtain a formulation. The surface to which the film was applied (inner curved surface or outer curved surface), the thickness of the film on the inner curved surface side, and the angle between the X direction and the A direction were as shown in Table 2.

The following four types of substrates were used:

The radius of curvature of the substrate was measured using a laser interferometer (manufactured by ZYGO), the direction with the smallest radius of curvature was defined as direction A, and the reciprocal of the radius of curvature at that time was defined as maximum curvature κA. Next, the direction perpendicular to direction A was defined as direction B, and the reciprocal of the radius of curvature in that direction was defined as minimum curvature κB.
Substrate 1: A transparent single-curved glass substrate having a maximum curvature κA in the A direction of 0.0003 and a maximum curvature κB in the B direction of 0.
Substrate 2: Transparent curved glass having a maximum curvature κA in the A direction of 0.0003 and a maximum curvature κB in the B direction of 0.0002.
Substrate 3: Transparent curved glass having a maximum curvature κA in the A direction of 0.03 and a maximum curvature κB in the B direction of 0.0003.
Substrate 4: A transparent single-bent glass substrate having a maximum curvature κA in the A direction of 0.03 and a maximum curvature κB in the B direction of 0.

(7) Appearance of the laminate (wrinkles)
The appearance of the laminated body produced in (6) was visually evaluated on the following 5-point scale, with B or higher being considered acceptable.
SS: There were no wrinkles at all.
S: There was a very slight wrinkle in one place.
A: There were wrinkles in several places at the S level.
B: There were wrinkles in several places that exceeded the level of A.
C: There were wrinkles large enough to cause problems in practical use.

(8) Interlayer Adhesion The interlayer adhesion of the laminate produced in (6) was evaluated on the following two-level scale, with A being acceptable.
A: No delamination occurred.
B: At least some delamination was observed.

(9) Heat-shielding property The total energy transmittance (Tts) through the laminate was measured in accordance with ISO 13837:2008 "Road vehicles -- Safety glazing materials -- Determination of solar transmittance" and evaluated on the following five-point scale. Note that light was incident from the outside of the bent sheet.
SS: The total energy transmittance (Tts) through the projection image display member was 50% or less.
S: The total energy transmittance (Tts) through the projection image display member was greater than 50% and not more than 60%.
A: The total energy transmittance (Tts) through the projection image display member was greater than 60% and equal to or less than 70%.
B: The total energy transmittance (Tts) through the projection image display member was greater than 70% and equal to or less than 80%.
C: The total energy transmittance (Tts) through the projection image display member exceeded 80%.

(10) Visibility A sensory evaluation was carried out on the visibility of the background through the laminate, and the visual visibility was evaluated on the following three levels, with A and B being considered acceptable.
A: The background looked clear.
B: The background appeared dark enough to cause no practical problems.
C: The background appeared darker than the level of B, and the background was not visible.

(11) Calculation of the difference between the average in-plane refractive index and the normal in-plane refractive index The average in-plane refractive index and the normal in-plane refractive index of layer A of the film were measured using a prism coupler SPA-400 manufactured by Cylon Technology. The wavelength of the laser used for the measurement was 633 nm, and the average in-plane refractive index was the average of the values measured in the main alignment axis direction and the direction perpendicular to the main alignment axis direction, and the normal in-plane refractive index was the average of the values measured from the main alignment axis direction and the direction perpendicular to the main alignment axis direction. Since layers B and C of the film are internal layers of the film, they were measured and calculated in the same manner as above using films of the layer B resin alone or the layer C resin alone prepared under the same conditions as the film, rather than the film itself. The average in-plane refractive index and the normal in-plane refractive index were taken as absolute values obtained by subtracting the refractive indexes determined for each layer, respectively.

(12) In-plane retardation A retardation measurement device (KOBRA-WPR) manufactured by Oji Scientific Instruments Co., Ltd. was used. The film was cut into a 10 cm square and placed on a large-format sample setting table at the bottom of the device. The film was then analyzed for the orientation angle from 0°, as defined by this measurement device, and the in-plane retardation at 587 nm for normal incidence. The orientation angle was measured from -90° to 90°.

(Resin used in the film)
The resins used in the examples of the present invention are described below. The refractive index difference was calculated from the in-plane average refractive index and the in-plane normal refractive index when a sheet made of each resin was stretched under the stretching conditions described in the examples. Within the range of stretching conditions described in the examples, the in-plane average refractive index and the in-plane normal refractive index all showed the same value.
Resin 1: A crystalline homopolyethylene terephthalate resin (difference between the average in-plane refractive index and the perpendicular in-plane refractive index = 0.1) exhibiting a glass transition temperature of 78°C, a melting point of 254°C, and a melting enthalpy of 40 J/g.
Resin 2: Crystalline polyethylene naphthalate resin (difference between in-plane average refractive index and perpendicular refractive index = 0.25) exhibiting a glass transition temperature of 124°C, a melting point of 262°C, a crystallization temperature of 200°C, and a melting enthalpy of 48 J/g.
Resin 3: Amorphous polyethylene terephthalate resin copolymerized with 33 mol % of cyclohexanedimethanol, exhibiting a glass transition temperature of 80° C. (difference between average in-plane refractive index and perpendicular in-plane refractive index = less than 0.01).
Resin 4: Amorphous homo-polymethylene methacrylate resin exhibiting a glass transition temperature of 101°C (difference between the in-plane average refractive index and the perpendicular refractive index = less than 0.01)
Resin 5: Amorphous polyethylene terephthalate resin blend having a glass transition temperature of 79°C, blended with Resin 3 and Resin 1 in a ratio of 85:15 (difference between in-plane average refractive index and perpendicular refractive index = 0.05).
Resin 6: Amorphous polyethylene terephthalate resin blend obtained by blending Resin 1 with polyethylene terephthalate resin copolymerized with 29 mol % of spiroglycol and 21 mol % of cyclohexanedicarboxylic acid, which has a glass transition temperature of 80°C, in a ratio of 70:30 (difference between the in-plane average refractive index and the in-plane refractive index = 0.05).
Resin 7: A crystalline polyethylene terephthalate resin copolymerized with 10 mol% isophthalic acid, exhibiting a glass transition temperature of 79°C, a melting point of 230°C, and a melting enthalpy of 12 J/g (difference between the in-plane average refractive index and the perpendicular refractive index = 0.08).

Example 1
Two thermoplastic resin layers with different main components were designated as layers A1 and B1, respectively. Resin 1 was used as the thermoplastic resin constituting layer A1, and Resin 3 was used as the thermoplastic resin constituting layer B1. Resins 1 and 3 were melted at 280°C in separate extruders and passed through five FSS-type leaf disc filters to remove foreign matter. They were then extruded using a gear pump while being metered so that the discharge ratio (lamination ratio) was Resin 1/Resin 3 = 1.00/1.07, and the flows were combined in a 273-layer feed block. The thickness of the final A1 layer was varied in a geometric progression from 130 nm to 180 nm, and the thickness of the final B1 layer was varied in a geometric progression from 137 nm to 190 nm, so that both surface layers were made of resin 1, and the adjacent A1 layer made of resin 1 and the B1 layer made of resin 3 from one surface of the film to the opposite surface satisfied the above-mentioned formulas 1 and 2 (however, the thickness of the A1 layers located on both surface layers was adjusted to a final thickness of 10 μm). The resulting molten laminate was then fed into a T-die and formed into a sheet, after which it was quenched and solidified on a casting drum maintained at a surface temperature of 25°C while applying an electrostatic voltage of 8 kV with a wire, to obtain an unoriented sheet. This unoriented sheet was then longitudinally stretched by differential roll speeds at a temperature of 90°C and a stretch ratio of 3.3 to obtain a uniaxially oriented sheet. The resulting uniaxially oriented sheet was then held at both ends with clips and introduced into a tenter, where it was transversely stretched at 100°C and a stretch ratio of 3.5, followed by heat treatment at 240°C for 10 seconds, relaxation in the transverse direction by 2.0% at the same temperature, and cooling at 150°C for 10 seconds to obtain a 50 μm thick film. The physical properties and characteristics of the resulting film are shown in Tables 1-1 and 1-2.

(Examples 2 to 13, 15 to 17, 19 to 20, 22, Reference Examples 1 and 2)
A film was obtained in the same manner as in Example 1, except that the resin, film configuration, and film-forming conditions were as shown in Tables 1-1 and 1-2. The physical properties and characteristics of the obtained film are shown in Tables 1-1 and 1-2. The number of layers was adjusted by changing the number of slits in the feed block, and the thickness was adjusted by changing the extrusion rate of each resin (the same applies below).

Example 14
A film was obtained in the same manner as in Example 12, except that the film was heat-treated at 183°C for 10 seconds, relaxed in the width direction by 3.6% at the same temperature, and then further stretched in the width direction by 3.1% in a cooling zone at 150°C. The physical properties and characteristics of the obtained film are shown in Table 1-2.

(Example 18)
A film was obtained in the same manner as in Example 14, except that the relaxation in the width direction was as shown in Table 1-2. The physical properties and characteristics of the obtained film are shown in Table 1-2.

(Example 21)
Three types of thermoplastic resin layers with different main components were designated as layers A2, B2, and C2, respectively. Resin 1 was used as the thermoplastic resin constituting layer A2, Resin 7 as the thermoplastic resin constituting layer B2, and Resin 3 as the thermoplastic resin constituting layer C2. Resins 1, 7, and 3 were melted in separate extruders at 270°C, 270°C, and 280°C, respectively, and then passed through seven FSS-type leaf disc filters. The resins were then extruded using a gear pump while measuring the discharge ratio (lamination ratio) so that Resin 1/Resin 7 = 1.00/1.02 and Resin 3/Resin 7 = 1.00/0.98, respectively, and merged in a 601-layer feed block. Note that both surface layers were made into the A2 layer, and the layers were laminated in a regular arrangement of A2 layer/B2 layer/C2 layer/B2 layer in the thickness direction. The thicknesses of the A2, B2, and C2 layers were designed to provide a flat reflectance spectrum in the wavelength range from 400 nm to 700 nm. That is, from one surface of the film to the opposite surface, the thickness of the A2 layer was varied in a geometric progression from 130 nm to 180 nm, the thickness of the B2 layer was varied from 137 nm to 190 nm, and the thickness of the C2 layer was varied from 144 nm to 200 nm, so that the adjacent A2 and B2 layers, B2 and C2 layers, and C2 and A2 layers satisfied the above-mentioned formulas 1 and 2, respectively (however, the thickness of the A2 layers located on both surfaces was adjusted to a final thickness of 10 μm). Subsequently, a film was produced in the same manner as in Example 1, except that the film production conditions were as shown in Table 1-2, to obtain a film with a thickness of 80 μm. Note that the explanation of formulas 1 and 2 above assumes the combination of layer A and layer B, but should be interpreted accordingly depending on the combination. The physical properties and characteristics of the obtained film are shown in Table 1-2.

(Reference example 3)
Resin 1 was used as the thermoplastic resin constituting the A1 layer, and Resin 4 was used as the thermoplastic resin constituting the B1 layer. Resins 1 and 2 were melted at 280°C in separate extruders, and foreign matter was removed through five FSS-type leaf disc filters. They were then extruded using a gear pump while being metered so that the discharge ratio (lamination ratio) was Resin 1/Resin 3 = 1.00/1.07, and the resulting mixtures were merged in a 273-layer feed block. The thickness of the final A1 layer was varied in a geometric progression from 130 nm to 180 nm, and the thickness of the final B1 layer was varied in a geometric progression from 137 nm to 190 nm, so that the adjacent A1 layer (made of Resin 1) and B1 layer (made of Resin 2) satisfied the aforementioned formulas 1 and 2, respectively, from one surface of the film to the opposite surface. The resulting molten laminate was then fed into a T-die and formed into a sheet, after which it was rapidly cooled and solidified on a casting drum maintained at a surface temperature of 25°C while an electrostatic voltage of 8 kV was applied using a wire, to obtain an unoriented sheet. The physical properties and characteristics of the resulting unoriented sheet (film) are shown in Table 1-2.

Example 23
Substrate 1 was used as the substrate, and the film obtained in Example 1 was used, and the film was arranged so that the film was the member on the curved inner surface side and the thickness of the film on the curved inner surface side was d2, and a bonded body was obtained by the method described in (6) above. The evaluation results of the obtained bonded body are shown in Table 2-1.

(Examples 24, 25, 28 to 41, 44 to 55, Comparative Examples 1 to 5)
A laminated body was obtained in the same manner as in Example 23, except that the configuration and production method of the laminated body were as shown in Tables 2-1 and 2-2. The evaluation results of the obtained laminated body are shown in Tables 2-1, 2-2, 2-3, and 2-4.

(Example 26)
One side of the film obtained in Example 1 was coated with the coating liquid for functional layer B described below using a wire bar coater, and then dried in a hot air oven at 80°C for 2 minutes. The coating was then cured by irradiating it with ultraviolet light ^at 300 mJ/cm2 using a UV irradiation device to form functional layer B, thereby obtaining a film having functional layer B. The coating amount of functional layer B was adjusted so that the dry film thickness was 3 μm. A bonded body was obtained in the same manner as in Example 23, except that the film obtained in this manner was used as in Table 2-1. The evaluation results of the obtained bonded body are shown in Table 2-1.

(Preparation of Coating Solution for Functional Layer B)
A mixture of DPHA (dipentaerythritol hexaacrylate), potassium tert-butoxide, and a photoinitiator ("IRGACURE" (registered trademark) 184, manufactured by BASF Japan) in a mass ratio of 99:1:1 was adjusted with MEK (methyl ethyl ketone) to a solids concentration of 40%. This coating agent was mixed with _a slurry of cesium tungsten oxide particles _Cs0.33WO3 with a solids concentration of 20% by mass in a solids mass ratio of 80:18.5 to prepare a coating solution for functional layer B.

(Example 27)
One side of the film obtained in Example 1 was coated with the coating liquid for functional layer C described below using a wire bar coater, and then dried in a hot air oven at 80°C for 2 minutes. The coating was then cured by irradiating 300 mJ/ ^cm2 of ultraviolet light using a UV irradiation device to form functional layer C, thereby obtaining a film having functional layer C. The coating amount of functional layer C was adjusted so that the dry film thickness was 3 μm. A bonded body was obtained in the same manner as in Example 23, except that the film obtained in this manner was used as in Table 2-1. The evaluation results of the obtained bonded body are shown in Table 2-1.

(Preparation of Coating Solution for Functional Layer C)
A coating liquid for functional layer C was prepared by mixing DPHA (dipentaerythritol hexaacrylate), an ultraviolet absorber (trade name: Tinuvin 326, manufactured by BASF, benzotriazole-based), a photopolymerization initiator (trade name: Irgacure 184, manufactured by BASF, α-hydroxyacetophenone-based), and a photopolymerization initiator (trade name: OXE01, manufactured by BASF, oxime ester-based) in a weight ratio of 100:1.5:5:0.3, and then adding MEK (methyl ethyl ketone) and cyclohexanone to adjust the solid content to 40% by weight.

(Example 42)
A film was obtained and further a laminated body was obtained in the same manner as in Example 26, except that the substrate was Substrate 3 and the film was Example 12. The evaluation results of the obtained laminated body are shown in Table 2-3.

(Example 43)
A film was obtained and further a laminated body was obtained in the same manner as in Example 27, except that the substrate was Substrate 3 and the film was Example 12. The evaluation results of the obtained laminated body are shown in Table 2-3.

According to the present invention, it is possible to provide a method for manufacturing a bonded body that can suppress appearance defects even when attached to glass with a complex curved surface shape, and an oriented film that can be suitably used in the method for manufacturing the bonded body. Furthermore, the bonded body obtained by the method for manufacturing the bonded body of the present invention has excellent properties as described above, and therefore can be suitably used in windows and information display devices of automobiles, buildings, etc.

Claims (22)

A method for producing a bonded body, comprising a bonding step of bonding a film onto a substrate,
The film has a structure in which two or more thermoplastic resin layers having different main components are regularly laminated in 51 to 2001 layers,
the direction in which the shrinkage rate S ₁₅₀ (%) of the film at 150°C is the largest is the X direction, the direction perpendicular to the X direction in the film plane is the Y direction, the shrinkage rate in the X direction at 150°C is S _150X (%), the shrinkage rate in the Y direction at 150°C is S _150Y (%), and S _150X -S _150Y is ΔS ₁₅₀ , where 0.7≦ΔS ₁₅₀ ≦10.0 is satisfied;
The method for producing a bonded body, wherein the maximum curvature of the film in the X direction after the bonding step is 0.0001 or more and 0.1 or less. The method for manufacturing a bonded body according to claim 1, wherein, when the direction in which the curvature of the bonded body is greatest is defined as direction A, the angle formed between the X direction and direction A is between 0° and 30°. The method for producing a laminate according to claim 1 or 2, wherein the film satisfies 0.1≦S _150X < 2.5 and −0.6≦S _150Y < 1.8. The method for manufacturing a bonded body according to claim 3, wherein the maximum curvature κA in the A direction is 0.0001 or more and 0.0050 or less. The method for producing a laminate according to claim 1 or 2, wherein the film satisfies 4.0≦S _150X ≦20.0 and 3.3≦S _150Y ≦19.7. The method for manufacturing a bonded body according to claim 5, wherein the maximum curvature κA in the A direction is greater than 0.0050 and less than or equal to 0.1. The method for manufacturing a laminate according to claim 1 or 2, wherein the film has a functional layer. The method for producing a bonded body according to claim 1 or 2, wherein when light with a wavelength of 300 to 2500 nm is incident on the film at an incident angle of 10°, the film has a continuous reflection band with a reflectance of 30% to 110% over a wavelength range of 20 nm to 1000 nm. The method for producing a bonded body according to claim 1 or 2, wherein the film has an average reflectance of 0% or more and 15% or less at wavelengths of 400 to 700 nm, and an average reflectance of 70% or more and 110% or less at wavelengths of 900 to 1200 nm. When the thickness of the film is D, and among the layer groups divided into two at a position D/2 from one surface, the layer group having the smaller average layer thickness constituting each layer group is called layer group A, and the layer group having the thicker average layer thickness is called layer group B,
The method for producing a bonded body according to claim 1 or 2, wherein in the bonding step, the film is arranged so that the inner curved surface side is layer group A. A window comprising a bonded body obtained by the method for manufacturing a bonded body described in claim 1 or 2. An information display device comprising a bonded body obtained by the method for manufacturing a bonded body described in claim 1 or 2. The laminate has a structure in which two or more thermoplastic resin layers having different main components are regularly laminated in 51 to 2001 layers,
An oriented film that satisfies 0.7≦ΔS _{150 ≦} 10.0, where the direction in which the shrinkage rate S ₁₅₀ (%) at 150°C is the largest is the X direction, the direction perpendicular to the X direction in the film plane is the Y direction, the shrinkage rate in the X direction at 150°C is S _150X (%), the shrinkage rate in the Y direction at 150°C is S _150Y (%), and S _150X −S _150Y is ΔS ₁₅₀ . The oriented film according to claim 13, wherein each of the thermoplastic resin layers comprises a polyester resin. The oriented film described in claim 13 or 14, wherein the outermost layers on both sides of the film are the same layer, and the thermoplastic resin that is the main component of the outermost layers has the highest glass transition temperature among the main components of the thermoplastic resin layers that make up the film. The oriented film according to claim 13 or 14, wherein the highest glass transition temperature of the oriented film is 90°C or higher and 140°C or lower. The oriented film according to claim 13 or 14, wherein the difference between the in-plane average refractive index and the perpendicular refractive index in at least one layer other than the outermost layer constituting the film is 0.01 or more and 0.30 or less. The oriented film according to claim 13 or 14, having an in-plane retardation of 1,500 nm or more and 10,000 nm or less. The oriented film according to claim 13 or 14, which satisfies 0.1≦S _150X < 2.5 and −0.6≦S _150Y < 1.8. The oriented film according to claim 13 or 14, wherein 4.0≦S _150X ≦20.0 and 3.3≦S _150Y ≦19.7 are satisfied. The oriented film of claim 13 or 14 has a reflection band with a continuous reflectance of 30% to 110% over a wavelength range of 20 nm to 1000 nm when light with a wavelength of 300 to 2500 nm is incident at an incident angle of 10°. The oriented film according to claim 13 or 14, wherein the average reflectance in the wavelength range of 400 to 700 nm is 0% or more and 15% or less, and the average reflectance in the wavelength range of 900 to 1200 nm is 70% or more and 110% or less.