JP7816342B2 - Laminate and manufacturing method thereof - Google Patents

Description

The present invention relates to a laminate comprising a substrate that can be used for applications such as an optical film and a protective film that protects the substrate, and a method for manufacturing the same.

Optical films are widely used as components of optical devices such as liquid crystal displays and organic electroluminescent displays. Examples include films used as substrates in devices. Specifically, it is common to form other layers on such substrates to obtain components with multiple layers that make up the device.

Optical films are required to have good optical properties and high resistance to heat in the environment in which they are used. For example, they should not shrink or undergo any other changes in shape even when subjected to thermal stress such as heating at 200°C for 10 minutes or at 145°C for 60 minutes.

From this perspective, crystalline resins, particularly resins containing crystalline alicyclic structure-containing polymers, are sometimes used as materials for such optical films. When using such crystalline resins, various processes such as stretching and heat setting may be performed to adjust the optical anisotropy, heat resistance, and various other properties (e.g., Patent Documents 1 and 2).

International Publication No. 2016/067893 (corresponding publication: U.S. Patent Application Publication No. 2017/306113) Japanese Patent Application Laid-Open No. 2021-24086

When processing a film made of a crystalline resin, undesirable phenomena such as wrinkles appearing on the surface and damage to the film's flatness can occur, resulting in a decrease in product quality. Furthermore, depending on the processing method, optical films may not be able to achieve sufficient heat resistance. For example, when subjected to a thermal load such as heating at 200°C for 10 minutes or 145°C for 60 minutes, suppression of shape change may not be achieved.

Therefore, the object of the present invention is to provide a substrate that suppresses the occurrence of wrinkles, maintains flatness when used as a substrate, and has high heat resistance, as well as a method for manufacturing the same.

As a measure to suppress the occurrence of wrinkles and maintain flatness when used as a substrate, it is considered to form a laminate of the substrate with a protective film. As a result of investigations into this point, the present inventors have found that by adopting a substrate and a protective film having a specific relationship in physical properties to form a laminate, it is possible to manufacture a product that can obtain high wrinkle suppression and heat resistance, and also found that such a laminate can be obtained by laminating a specific pre-annealed substrate and a pre-annealed protective film to form a pre-annealed laminate and then annealing the laminate in that state, thereby completing the present invention.
That is, the present invention provides the following.

[1] A laminate having a long shape, comprising a substrate and a protective film provided on one surface of the substrate,
the substrate is a layer of a resin containing a crystalline alicyclic structure-containing polymer,
A laminate, wherein the substrate and the protective film satisfy the following formulas (1) and (2):
E's/E'p<1 (1)
−0.4≦Fs−Fp≦0.4 (2)
however,
E's is the storage modulus of the substrate at 180°C,
E'p is the storage modulus of the protective film at 180°C,
Fs is the heat shrinkage rate (%) of the substrate in the longitudinal direction of the laminate at 180°C for 2 minutes,
Fp is the heat shrinkage rate (%) of the protective film in the longitudinal direction of the laminate at 180° C. for 2 minutes.
[2] The laminate according to [1], wherein the protective film is a layer of a resin containing a crystalline polymer.
[3] The laminate according to [1] or [2], wherein the resin containing the crystalline alicyclic structure-containing polymer constituting the substrate is a hydrogenated product of a ring-opening polymer of dicyclopentadiene.
[4] A method for producing the laminate according to any one of [1] to [3],
A manufacturing method comprising: a step of laminating a pre-annealed substrate and a pre-annealed protective film to obtain a pre-annealed laminate comprising the pre-annealed substrate and the pre-annealed protective film, wherein the pre-annealed substrate is a layer of a resin containing a crystalline alicyclic structure-containing polymer; and a step of annealing the pre-annealed laminate.
[5] The manufacturing method according to [4], wherein the pre-annealed protective film is a layer of a resin containing a crystalline polymer.
[6] The manufacturing method according to [4] or [5], wherein the resin containing the crystalline alicyclic structure-containing polymer constituting the pre-annealing base material is a hydrogenated product of a ring-opening polymer of dicyclopentadiene.
[7] The manufacturing method according to any one of [4] to [6], wherein the annealing treatment includes heating the pre-annealing laminate while restraining it in at least one direction among its in-plane directions.

The present invention provides a laminate that suppresses the occurrence of wrinkles, maintains flatness when used as a substrate, and allows for easy supply of a highly heat-resistant substrate when needed, as well as a method for manufacturing the same.

FIG. 1 is a cross-sectional view schematically showing a laminate of the present invention.

The present invention will be described in detail below with reference to embodiments and examples. However, the present invention is not limited to the embodiments and examples shown below, and may be modified and implemented as desired within the scope of the claims of the present invention and their equivalents.

In the following description, "long" film refers to a film whose length is at least five times its width, preferably 10 times or more, and specifically refers to a film long enough to be wound into a roll for storage or transportation. There is no particular upper limit to the length of the film, and it can be, for example, up to 100,000 times its width.

Unless otherwise specified, the term "adhesive" refers not only to adhesives in the narrow sense (adhesives whose shear storage modulus at 23°C is 1 MPa to 500 MPa after irradiation with energy rays or after heat treatment), but also to pressure-sensitive adhesives whose shear storage modulus at 23°C is less than 1 MPa.

In the following description, unless otherwise specified, the orientation of elements as "parallel," "vertical," and "orthogonal" may include an error within a range that does not impair the effect of the present invention, for example, within ±3°, ±2°, or ±1°.

[Overview of the laminate]
The laminate of the present invention includes a substrate and a protective film provided on one surface of the substrate, that is, the laminate includes the substrate and the protective film as its constituent layers.

A substrate is a film intended for use as a component of an optical device such as a display device. On the other hand, a protective film is a film that is attached to a substrate for the purpose of protecting the substrate, and can be peeled off when the substrate is used in the manufacture of the device or in any subsequent process.

The protective film may be provided in direct contact with the substrate, but is usually provided on the substrate via an adhesive layer. That is, the substrate and protective film are bonded via an adhesive layer, thereby forming a laminate in which the substrate, adhesive layer, and protective film layer are provided in this order.

Figure 1 is a cross-sectional view schematically illustrating a laminate of the present invention. In Figure 1, the laminate 10 comprises a substrate 110 and a composite film 120 provided on one surface thereof, with the composite film comprising a protective film 121 and an adhesive layer 122. In this example, the protective film is provided on only one of the front and back surfaces of the substrate, but the present invention is not limited to this. For example, one protective film may be provided on each side of the substrate.

In Figure 1, protective film 121 is a layer that provides the mechanical strength and other desired physical properties of a protective film, while adhesive layer 122 is a layer that provides the function of adhering substrate 110 to protective film 121. Adhesive layer 122 is typically thinner and more flexible than protective film 121, and therefore does not substantially affect the mechanical strength of composite film 120 as a whole in relation to in-plane stretching.

The substrate is a layer of a resin containing a crystalline alicyclic structure-containing polymer. In the following explanation, this resin may be specifically referred to as resin (a1) to distinguish it from general resins. On the other hand, the resin that constitutes the protective film may be specifically referred to as resin (b1).

In a laminate, the substrate may be a single-layer structure or a multi-layer structure consisting of multiple layers, but is usually a single-layer structure. The protective film may also be a single-layer structure or a multi-layer structure consisting of multiple layers, but is usually a single-layer structure.

[Physical properties of laminate]
The substrate and the protective film constituting the laminate satisfy the following formulas (1) and (2).
E's/E'p<1 (1)
−0.4≦Fs−Fp≦0.4 (2)

In the formula, E's is the storage modulus of the substrate at 180°C, and E'p is the storage modulus of the protective film at 180°C. In the following description, unless otherwise specified, elastic modulus means storage modulus. The value of E's/E'p is less than 1, preferably 0.95 or less, and more preferably 0.90 or less. The lower limit of E's/E'p is not particularly limited, but can be 0.1 or more. The values of E's and E'p are not particularly limited, but can be, for example, 1.0 x 10 ⁷ Pa or more and 1.0 x 10 ⁹ Pa or less. The elastic modulus can be measured by peeling the substrate and protective film of the laminate to obtain sample films, and performing extensional viscoelasticity measurement at 180°C using a dynamic viscoelasticity measuring device (e.g., Hitachi High-Tech Science Corporation, product name: DMA7100).

In the formula, Fs is the heat shrinkage rate of the substrate in the longitudinal direction of the laminate at 180°C for 2 minutes, and Fp is the heat shrinkage rate of the protective film in the longitudinal direction of the laminate at 180°C for 2 minutes. Fs and Fp are percentage values determined by peeling the substrate and protective film from the laminate, cutting each of them out at 23°C (room temperature) to obtain a square sample film having sides parallel to the longitudinal or width direction of the laminate, and measuring the change in the length of the sides of the sample film due to heating. More specifically, the heat shrinkage rate can be determined according to the following formula (I):
Heat shrinkage rate (%) = [(L _B - L _A ) / L _B ] × 100 (I)

In the formula, L _B represents the length of a side of the sample film before heating, and L _A represents the length of a side of the sample film after heating. A positive value for the heat shrinkage rate indicates that the film shrinks upon heating, and a negative value indicates that the film elongates upon heating. When determining the heat shrinkage rate in the longitudinal direction of the laminate, the heat shrinkage rate is calculated from the length of the side of the sample film parallel to the longitudinal direction of the laminate.

The value of Fs - Fp is the difference between the percentages. The value of Fs - Fp is -0.4% or more, preferably -0.3% or more, and 0.4% or less, preferably 0.3% or less. The values of Fs and Fp are not particularly limited, but can be, for example, -0.3% or more and 0.5% or less.

The inventors have discovered that when a long laminate includes a substrate that is a layer of resin (a1) and a protective film, and the substrate and protective film satisfy the above formulas (1) and (2), the occurrence of wrinkles in the laminate can be suppressed, the laminate can be handled while maintaining its flatness, and the substrate can be easily manufactured as a substrate with high heat resistance. Specifically, curling of the laminate can be suppressed, allowing the laminate to be transported without curling. Furthermore, the physical properties that are required to be low for the product, such as the substrate heat shrinkage rate at 200°C for 10 minutes and the substrate heat shrinkage rate at 145°C for 60 minutes, can be maintained at favorably low values.

The laminate of the present invention preferably has a small amount of curl. The amount of curl can be determined by cutting out a 50 mm x 50 mm square sample film from the laminate in an environment of 23°C (room temperature), placing it on a horizontal, flat surface, measuring the amount by which the four corners of the sample film lift above the horizontal surface (the amount of curl), and calculating the average value of the four corners. The amount of curl is preferably 8.5 mm or less, more preferably 7.5 mm or less. There is no particular lower limit to the amount of curl, but ideally it is 0.0 mm.

[Base material]
The substrate is a layer of resin (a1), i.e., a resin containing a crystalline alicyclic structure-containing polymer. The substrate may be a layer consisting of resin (a1) alone. By using resin (a1) as the substrate, the substrate can exhibit good mechanical strength, heat resistance, and moldability.

A "crystalline" polymer is one that has a melting point Tm. "Having a melting point Tm" means that the melting point can be observed using a differential scanning calorimeter (DSC). In the following description, a polymer that has crystallinity may be simply referred to as a "crystalline polymer." Furthermore, a resin that contains a polymer that has crystallinity may be simply referred to as a "crystalline resin." A polymer that contains an alicyclic structure is a polymer that contains an alicyclic structure within its molecule, and a polymer that has crystallinity is a crystalline polymer that contains an alicyclic structure within its molecule.

The alicyclic structure-containing polymer may be a polymer or its hydrogenated product obtained by a polymerization reaction using a cyclic olefin as a monomer. The alicyclic structure-containing polymer may be used alone or in combination of two or more types in any ratio.

Examples of alicyclic structures contained in alicyclic structure-containing polymers include cycloalkane structures and cycloalkene structures. Of these, cycloalkane structures are preferred because they facilitate the production of optical films with excellent properties such as thermal stability. The number of carbon atoms contained in one alicyclic structure is preferably 4 or more, more preferably 5 or more, and preferably 30 or less, more preferably 20 or less, and particularly preferably 15 or less. Having the number of carbon atoms contained in one alicyclic structure within the above range ensures a high level of balance between mechanical strength, heat resistance, and moldability.

In the alicyclic structure-containing polymer, the ratio of the structural units having an alicyclic structure to all structural units is preferably 30% by weight or more, more preferably 50% by weight or more, particularly preferably 70% by weight or more. By increasing the ratio of the structural units having an alicyclic structure in the alicyclic structure-containing polymer as described above, heat resistance can be improved.
In the alicyclic structure-containing polymer, the remainder other than the structural unit having the alicyclic structure is not particularly limited and can be appropriately selected depending on the intended use.

Examples of the crystalline alicyclic structure-containing polymer include the following polymers (α) to (δ): Among these, polymer (β) is preferred as the crystalline alicyclic structure-containing polymer because it is easy to obtain a substrate having excellent heat resistance.
Polymer (α): A ring-opening polymer of a cyclic olefin monomer, which is crystalline.
Polymer (β): A hydrogenated product of polymer (α) that is crystalline.
Polymer (γ): An addition polymer of a cyclic olefin monomer, which is crystalline.
Polymer (δ): A crystalline polymer such as a hydrogenated polymer (γ).

Specifically, crystalline alicyclic structure-containing polymers are preferably crystalline ring-opening polymers of dicyclopentadiene and crystalline hydrogenated ring-opening polymers of dicyclopentadiene, with crystalline hydrogenated ring-opening polymers of dicyclopentadiene being particularly preferred. Here, a ring-opening polymer of dicyclopentadiene refers to a polymer in which the proportion of dicyclopentadiene-derived structural units to all structural units is typically 50% by weight or more, preferably 70% by weight or more, more preferably 90% by weight or more, and even more preferably 100% by weight.

The hydrogenated product of the ring-opening polymer of dicyclopentadiene preferably has a high ratio of racemo dyads. Specifically, the ratio of racemo dyads in the repeating units of the hydrogenated product of the ring-opening polymer of dicyclopentadiene is preferably 51% or more, more preferably 70% or more, and particularly preferably 85% or more. A high ratio of racemo dyads indicates high syndiotactic stereoregularity. Therefore, the higher the ratio of racemo dyads, the higher the melting point of the hydrogenated product of the ring-opening polymer of dicyclopentadiene tends to be. The ratio of racemo dyads can be determined based on the ^13C -NMR spectrum analysis described in the Examples below.

As a crystalline alicyclic structure-containing polymer, a polymer obtained by the manufacturing method disclosed in WO 2018/062067 can be used.

The melting point (Tm) of the crystalline alicyclic structure-containing polymer is preferably 200°C or higher, more preferably 230°C or higher, and preferably 290°C or lower. By using a crystalline polymer with such a melting point (Tm), a substrate with an even better balance between moldability and heat resistance can be obtained.

Typically, crystalline polymers, such as alicyclic structure-containing polymers, have a glass transition temperature (Tg). The specific glass transition temperature (Tg) of a crystalline polymer is not particularly limited, but is typically 85°C or higher and 170°C or lower.

The glass transition temperature (Tg) and melting point (Tm) of a polymer can be measured by the following method. First, the polymer is melted by heating, and the molten polymer is rapidly cooled with dry ice. Next, using this polymer as a test specimen, the glass transition temperature (Tg) and melting point (Tm) of the polymer can be measured using a differential scanning calorimeter (DSC) at a heating rate of 10°C/min (heating mode).

The weight-average molecular weight (Mw) of crystalline polymers such as crystalline alicyclic structure-containing polymers is preferably 1,000 or more, more preferably 2,000 or more, and preferably 1,000,000 or less, more preferably 500,000 or less. Crystalline polymers with such weight-average molecular weights have an excellent balance between moldability and heat resistance.

The molecular weight distribution (Mw/Mn) of crystalline polymers such as crystalline alicyclic structure-containing polymers is preferably 1.0 or greater, more preferably 1.5 or greater, and preferably 4.0 or less, more preferably 3.5 or less. Here, Mn represents the number average molecular weight. Crystalline polymers with such a molecular weight distribution have excellent moldability. The weight average molecular weight (Mw) and molecular weight distribution (Mw/Mn) of crystalline polymers can be measured in polystyrene equivalent values by gel permeation chromatography (GPC) using tetrahydrofuran as the developing solvent.

The proportion of the crystalline alicyclic structure-containing polymer in resin (a1) is preferably 50% by weight or more, more preferably 70% by weight or more, and particularly preferably 90% by weight or more. By ensuring that the proportion of the crystalline alicyclic structure-containing polymer is equal to or greater than the lower limit of the above range, the heat resistance of the substrate can be effectively improved. The upper limit of the proportion of the crystalline polymer can be 100% by weight or less.

The crystalline alicyclic structure-containing polymer contained in resin (a1) does not need to be crystallized before the substrate is produced. However, when the substrate is formed in the laminate of the present invention, the crystalline polymer contained in the substrate is preferably crystallized and preferably has a high degree of crystallinity. A high degree of crystallinity can better exhibit the effects of the present invention, such as heat resistance. The specific range of crystallinity is preferably 20% or more, more preferably 25% or more, and particularly preferably 30% or more. The upper limit of the degree of crystallinity is not particularly limited, but can be 95% or less. The degree of crystallinity of the crystalline polymer can be measured by density analysis, X-ray diffraction analysis, or differential scanning calorimetry.

Resin (a1) may contain optional components in addition to the crystalline alicyclic structure-containing polymer. Examples of optional components include antioxidants, light stabilizers, waxes, nucleating agents, fluorescent brighteners, ultraviolet absorbers, inorganic fillers, colorants, flame retardants, flame retardant assistants, antistatic agents, plasticizers, near-infrared absorbers, lubricants, fillers, and any polymer other than a crystalline polymer. Furthermore, the optional components may be used alone or in combination of two or more in any ratio.

The thickness of the substrate is preferably 5 μm or more, more preferably 10 μm or more, and preferably 160 μm or less, more preferably 150 μm or less.

[Protective film]
From the viewpoint of easily obtaining a protective film having the specific physical properties described above, the resin (b1), i.e., the resin constituting the protective film in the protective film, preferably comprises a layer of a resin containing a crystalline polymer. However, particularly from the viewpoint of satisfying the condition of formula (1), the material constituting the protective film in the protective film can usually be a material different from the resin (a1) constituting the substrate. Examples of such materials include resins that can exhibit a lower storage modulus than the above-mentioned examples of resin (a1) used as a constituent element of the substrate, resins containing a crystalline polymer other than a crystalline alicyclic structure-containing polymer, and other materials.

Examples of crystalline polymers constituting resin (b1) include polymers other than those used as components of the substrate among the examples of polymers constituting resin (a1) described above.

Further examples of crystalline polymers that may constitute resin (b1) include styrene-based polymers (e.g., homopolymers of styrene or styrene derivatives or copolymers with other monomers polymerizable therewith); cellulose-based polymers such as triacyl cellulose; polyolefins such as polyethylene and polypropylene; polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; polyarylene sulfides such as polyphenylene sulfide; polyvinyl alcohol; polycarbonate; polyarylate; polyethersulfone; polysulfone; polyarylsulfone; polyvinyl chloride; acrylic polymers such as polymethyl methacrylate and polyacrylonitrile; polyimide; and polyamide. These polymers may be homopolymers or copolymers.

In particular, examples of crystalline polystyrene-based polymers include those described in JP 2011-118137 A.

Resin (b1) may contain optional components in addition to the polymer. Examples of optional components that may be contained in resin (b1) include the same components as the examples of optional components that may be contained in resin (a1). Resin (b1) may contain a single polymer, or a combination of two or more polymers in any ratio. The proportion of polymer in 100% by weight of resin (b1) is preferably 70% by weight or more, more preferably 80% by weight or more, and even more preferably 85% by weight or more, and is usually 100% by weight or less, and may be 100% by weight.

The glass transition temperature of resin (b1) is preferably 60°C or higher, more preferably 70°C or higher, and preferably 180°C or lower, more preferably 170°C or lower. When the glass transition temperature of resin (b1) is equal to or higher than the lower limit, the heat resistance of the laminate can be effectively improved. Furthermore, when the glass transition temperature is equal to or lower than the upper limit, moldability can be improved.

When a protective film is combined with an adhesive layer to form a composite film, the surface of the protective film that contacts the adhesive layer can be subjected to a surface treatment such as corona treatment or plasma treatment. That is, one surface of the protective film can be surface-treated, and an adhesive layer can be formed on that surface. Such a surface treatment enhances the adhesion between the protective film and the adhesive layer, thereby making it easy to peel the substrate from the protective film without leaving any adhesive residue.

The thickness of the protective film in the laminate is preferably 5 μm or more, more preferably 10 μm or more, and preferably 150 μm or less, more preferably 140 μm or less.

When the protective film in the laminate of the present invention is a resin layer containing a crystalline polymer, the polymer constituting the protective film may be crystallized to a certain degree of crystallinity or higher. The specific range of crystallinity is preferably 20% or higher, more preferably 25% or higher, and particularly preferably 30% or higher. The upper limit of the crystallinity is not particularly limited, but may be 95% or lower.

[Adhesive layer]
When the laminate of the present invention includes an adhesive layer, the adhesive constituting the adhesive layer may be one having various polymers as a base polymer. Examples of such base polymers include acrylic polymers, urethane polymers, polyester polymers, rubber polymers, epoxy polymers, and silicone polymers. The adhesive may also contain optional components such as a polymerization initiator, a curing agent, an ultraviolet absorber, a colorant, and an antistatic agent in combination with the base polymer.
The adhesive includes a pressure-sensitive adhesive.

Commercially available adhesives can be used. Additionally, various adhesive layers are commercially available as adhesive films, and these can be used to form the adhesive layer. The adhesive layer may have a single-layer structure or a multi-layer structure.

The thickness of the adhesive layer is not particularly limited and can be, for example, in the range of 3 μm to 30 μm, such as 5 μm to 20 μm.

[Method for manufacturing laminate]
The laminate of the present invention can be produced by any method. From the viewpoint of easily producing a laminate that satisfies the requirements defined by formulas (1) and (2), the laminate of the present invention is preferably produced by a production method including the following steps (1) and (2). Hereinafter, this production method will be described as a method for producing the laminate of the present invention.
Step (1): A step of laminating a pre-annealed substrate and a pre-annealed protective film to obtain a pre-annealed laminate comprising the pre-annealed substrate and the pre-annealed protective film.
Step (2): A step of annealing the pre-annealing laminate.

[Base material before annealing]
Examples of materials for the pre-annealed substrate used in step (1) include the same materials as those listed above as examples of the resin (a1) that constitutes the substrate of the laminate of the present invention. However, since the pre-annealed substrate and the pre-annealed protective film may have storage moduli and thermal shrinkage coefficients different from those of the substrate and the protective film in the laminate, they do not necessarily need to satisfy the above formulas (1) and (2) at this point.

The method for preparing the pre-annealed substrate is not particularly limited, and it can be prepared by any film production method. Specifically, the pre-annealed substrate can be prepared by employing a known molding method such as melt extrusion to mold resin (a1) into the shape of a long film. Alternatively, a commercially available product may be used as the pre-annealed substrate.

Films formed from resin (a1) by a molding method such as melt extrusion, or commercially available films of resin (a1), can be used as pre-annealed substrates as is. Alternatively, these films may be used as raw films, subjected to any treatment as necessary, and then used as pre-annealed substrates. For example, raw films may be subjected to a stretching process to produce films with the desired retardation, dimensions, and other properties, which can then be used as pre-annealed substrates. Furthermore, in order to obtain the desired properties, a process of promoting crystallization of resin (a1) may be carried out after stretching.

The stretching direction is not limited, and examples include the longitudinal direction, width direction, and diagonal direction. Here, the diagonal direction refers to a direction perpendicular to the thickness direction, but neither parallel nor perpendicular to the width direction. The stretching direction may be one direction or two or more directions. Therefore, stretching methods include, for example, uniaxial stretching methods, such as a method in which a raw film is uniaxially stretched in the longitudinal direction (longitudinal uniaxial stretching method) or a method in which a raw film is uniaxially stretched in the width direction (transverse uniaxial stretching method); biaxial stretching methods, such as a simultaneous biaxial stretching method in which a raw film is stretched in the longitudinal direction and simultaneously stretched in the width direction, and a sequential biaxial stretching method in which a raw film is stretched in one of the longitudinal and width directions and then stretched in the other direction; a method in which a raw film is stretched in a diagonal direction (diagonal stretching method); and combinations thereof.

Examples of uniaxial stretching methods include fixed-end uniaxial stretching and free-end uniaxial stretching. Fixed-end uniaxial stretching is a stretching method in which the end of the raw film in the direction perpendicular to the stretching direction is fixed, while free-end uniaxial stretching is a stretching method in which the end of the raw film in the direction perpendicular to the stretching direction is not fixed. Longitudinal uniaxial stretching is often free-end uniaxial stretching, and transverse uniaxial stretching is often fixed-end uniaxial stretching.

The stretching ratio can be adjusted as appropriate so that the substrate in the laminate has the desired phase difference, dimensions, and other properties. Specifically, it is preferably 1x or more, more preferably 1.01x or more, and preferably 15x or less, more preferably 11x or less. When the stretching is biaxial, it is preferable that the areal ratio, i.e., the product of the stretching ratios in two directions, be within this range.

The stretching temperature is preferably at least "Tg + 5°C," more preferably at least "Tg + 10°C," and preferably at most "Tg + 100°C," more preferably at most "Tg + 90°C." Here, "Tg" represents the glass transition temperature of the polymer being stretched. When the stretching temperature is at or above the lower limit of the above range, the raw film is sufficiently softened to allow for uniform stretching. Furthermore, when the stretching temperature is at or below the upper limit of the above range, hardening of the raw film due to the progression of polymer crystallization can be suppressed, allowing for smooth stretching and the development of large birefringence through stretching. Furthermore, the resulting substrate typically has a reduced haze and is therefore more transparent.

The crystallization promotion process can be carried out by heating the film after the stretching process. Such heating can be carried out by controlling the dimensions of the film and maintaining the post-stretching dimensions, or by shrinking the film by a small, controlled factor from the post-stretching dimensions. When shrinking the film, the dimensional change rate is preferably 0.90 times or more and less than 1 time. When shrinking the film in two directions, it is preferable that the areal magnification, i.e., the product of the dimensional change rates in the two directions, be within this range. The shrinking rate is the ratio of the post-shrinking dimension to the pre-shrinking dimension, which is taken as 1.

The heating temperature in the crystallization promotion step is typically equal to or higher than the glass transition temperature (Tg) of the crystalline polymer and equal to or lower than the melting point (Tm) of the crystalline polymer. More specifically, the heating temperature is preferably equal to or higher than Tg°C, more preferably equal to or higher than Tg + 10°C, and is preferably equal to or lower than Tm - 10°C, more preferably equal to or lower than Tm - 20°C. By keeping the heating temperature within this range, it is possible to rapidly promote the crystallization of the crystalline polymer while suppressing cloudiness due to the progression of crystallization.

The heat treatment time is preferably at least 1 second, more preferably at least 5 seconds, and preferably at most 30 minutes, more preferably at most 15 minutes.

[Protective film and adhesive layer before annealing]
Examples of materials for the pre-annealed protective film used in step (1) include the same materials as those listed above as examples of the resin (b1) that is the material constituting the protective film of the laminate of the present invention.

The method for preparing the pre-annealed protective film is not particularly limited, and it can be prepared by any film manufacturing method. Specifically, the pre-annealed protective film can be prepared by employing a known molding method such as melt extrusion to mold resin (b1) into a long film shape. Alternatively, a commercially available product can be used as the pre-annealed protective film. The pre-annealed protective film may be a stretched film, or it may be a film that has not been subjected to any particular stretching treatment.

Prior to step (1), an adhesive layer can be provided on the surface of the pre-annealed protective film to form a composite film. The adhesive layer can be formed by applying an adhesive to the surface of the pre-annealed protective film. The applied adhesive layer can be further subjected to a curing treatment, if necessary, to form an adhesive layer with the desired physical properties. Alternatively, the adhesive layer can be provided by transferring a layer of an adhesive film onto the surface of the pre-annealed protective film.

Examples of coating methods for applying adhesives include wire bar coating, spraying, roll coating, gravure coating, die coating, curtain coating, slide coating, and extrusion coating. Examples of adhesive curing processes include drying, such as vacuum drying, heat drying, and combinations of these.

[Physical Properties of Substrate and Protective Film Before Annealing]
Since the pre-annealed substrate is a layer of a resin containing a crystalline alicyclic structure-containing polymer, the polymer constituting the pre-annealed substrate can be crystallized to a certain degree of crystallinity or higher. The specific range of crystallinity is preferably 20% or higher, more preferably 25% or higher, and particularly preferably 30% or higher. The upper limit of the crystallinity is not particularly limited, but can be 95% or lower.

When the pre-annealed protective film is a resin layer containing a crystalline polymer, the polymer constituting the pre-annealed protective film may be crystallized to a certain degree of crystallinity or higher. The specific range of crystallinity is preferably 20% or higher, more preferably 25% or higher, and particularly preferably 30% or higher. The upper limit of crystallinity is not particularly limited, but may be 95% or lower.

The storage modulus and heat shrinkage rate of the pre-annealed substrate and pre-annealed protective film can be adjusted appropriately by adjusting the materials and preparation conditions so that the storage modulus and heat shrinkage rate of the substrate and protective film in the finished laminate are the desired values described above. The storage modulus and heat shrinkage rate of the pre-annealed substrate and pre-annealed protective film, as well as their ratio, are not particularly limited, but are preferably within the following ranges:

The ratio pE's/pE'p of the storage modulus pE's of the substrate at 180°C before annealing to the storage modulus pE'p of the protective film at 180°C before annealing is preferably a value within a specific range. The value of pE's/pE'p is preferably less than 1, more preferably 0.95 or less, and even more preferably 0.90 or less. The lower limit of pE's/pE'p is not particularly limited, but can be 0.1 or more. The values of pE's and pE'p are not particularly limited, but can be, for example, 1.0 x 10 ⁷ Pa or more and 1.0 x 10 ⁹ Pa or less.

Furthermore, it is preferable that the difference pFs (%) between the thermal shrinkage rate of the pre-annealed base material in the longitudinal direction of the laminate at 180°C for 2 minutes and the thermal shrinkage rate pFp (%) of the pre-annealed protective film in the longitudinal direction of the laminate at 180°C for 2 minutes, i.e., pFs - pFp, is within a specific range. The value of pFs - pFp is preferably -1.0% or greater, more preferably -0.8% or greater, and is preferably 1.0% or less, more preferably 0.8% or less. The values of pFs and pFp are not particularly limited, but can be, for example, -0.3% or greater and 1.0% or less.

By ensuring that the values of pE's/pE'p and pFs-pFp are within the above preferred ranges, the laminate of the present invention can be easily manufactured, comprising a substrate and a protective film that satisfy the above formulas (1) and (2).

[Step (1)]
Step (1) can be performed by overlapping a long pre-annealed substrate and a pre-annealed protective film with their longitudinal directions aligned and applying pressure to them. Pressurization can be performed continuously using a device that pressurizes a long film, such as a nip roll. When the pre-annealed protective film includes an adhesive layer and forms a composite film, the surface of the composite film on the adhesive layer side can be bonded to the surface of the pre-annealed substrate, thereby obtaining a pre-annealed laminate in which the pre-annealed substrate and the pre-annealed protective film are bonded via the adhesive layer.

[Step (2)]
The annealing treatment in step (2) can be performed by heating the pre-annealed laminate while restraining it in at least one of its in-plane directions, for example, by restraining the pre-annealed laminate in its longitudinal direction, width direction, or both.

Annealing treatment involving longitudinal restraint of the pre-annealed laminate can be performed, for example, using a roll-supported film dryer. A roll-supported dryer is equipped with an upstream nip roll, a downstream nip roll, and an oven located between them. By adjusting the peripheral speed ratio between the upstream and downstream nip rolls, a long film is conveyed between the nip rolls while tension is applied, and the film passes through the oven between them. The film is guided within the oven only by a non-restraining roll supporting the film from below, allowing the film to be heated within the oven without restraining it in the width direction. The pre-annealed laminate can be conveyed along its longitudinal direction, continuously introduced into the dryer, and heated to perform the annealing treatment. In this case, the tension applied to the film is preferably 3 N/m or more and 25 N/m or less.

Annealing, which involves restraining the pre-annealed laminate in the longitudinal direction, can be carried out, for example, using equipment with a structure similar to that used for stretching. More specifically, annealing can be carried out using equipment such as a tenter-type stretching machine that can continuously heat a long film by controlling both the longitudinal and width dimensions of the film. The film is gripped within the stretching machine and transported and heated while maintaining its longitudinal and width dimensions unchanged.

The heating temperature in the annealing treatment is typically equal to or higher than the glass transition temperature (Tg) of the crystalline polymer and equal to or lower than the melting point (Tm) of the crystalline polymer. More specifically, the heating temperature is preferably equal to or higher than Tg + 20°C, more preferably equal to or higher than Tg + 40°C, and is preferably equal to or lower than Tm - 20°C, more preferably equal to or lower than Tm - 40°C. The heating time is preferably equal to or higher than 5 seconds, more preferably equal to or higher than 10 seconds, while preferably equal to or lower than 30 minutes, more preferably equal to or lower than 15 minutes. By keeping the heating temperature and time within these ranges, a good annealing treatment can be achieved, and a laminate of the present invention comprising an annealed substrate and protective film can be obtained.

When a pre-annealed substrate, which is a film of a resin containing a crystalline alicyclic structure-containing polymer, is annealed alone without a protective film, its flatness is easily impaired. This phenomenon is particularly pronounced when the pre-annealed substrate is stretched at a high areal ratio prior to annealing. One way to reduce this impairment of flatness is to laminate the substrate with a protective film prior to annealing. However, simply providing a protective film is unlikely to reduce the impairment of flatness, and the resulting substrate may not exhibit sufficient heat resistance upon annealing.

The inventors have discovered that by appropriately adjusting the materials of the pre-annealed substrate and pre-annealed protective film and the processing conditions prior to the annealing treatment so that the substrate and protective film after annealing satisfy the above formulas (1) and (2), a pre-annealed laminate is produced, and then annealing this laminate, a laminate with good flatness and heat resistance can be easily produced.

[Optional step]
The method for producing a laminate of the present invention may further include any optional steps in addition to the steps (1) and (2) described above. Examples of such optional steps include a step of forming an additional layer, such as a conductive layer, on the surface of the substrate included in the laminate, and a step of winding the laminate to obtain a wound body.

[Uses of laminate]
The laminate of the present invention can be used as it is as a component of an optical device or a component of other electronic and electrical components, not limited to optical devices. Alternatively, the protective film can be peeled off from the laminate of the present invention, and the remaining substrate can be used as a component of an optical device or a component of other electronic and electrical components.
Examples of components of optical devices include substrate films, retardation films, polarizing films, and light diffusion sheets in displays such as liquid crystal displays and organic electroluminescence displays, as well as other devices. Taking advantage of their flexibility, substrate films are particularly useful as touch panel substrate films and flexible display substrate films. Other preferred applications include light-collecting sheets, optical cards, and other components.
Examples of other components of electronic and electrical parts include films for flexible printed circuit boards, film capacitors, high-frequency circuit board films, antenna substrate films, films for battery separators, and release films.
The laminate can maintain good flatness, undergo little change in shape due to heat load, and curl little in a high-temperature environment. Therefore, it can be particularly useful as a substrate for manufacturing an optical element (e.g., a conductive layer included in a touch panel) whose formation process is performed at high temperatures. The substrate in the laminate of the present invention can also be particularly useful as a retardation layer after peeling from the laminate by providing a desired retardation. The substrate in the laminate of the present invention can further be used as a protective film to protect a polarizer, taking advantage of its high flatness and heat resistance.

The present invention will be described in more detail below with reference to examples. However, the present invention is not limited to the examples shown below, and can be modified and implemented as desired within the scope of the claims of the present invention and their equivalents.

In the following explanation, "%" and "parts" used to represent amounts are by weight unless otherwise specified. Furthermore, the operations described below were carried out at room temperature and pressure unless otherwise specified.

[Evaluation method]
(Weight average molecular weight Mw and number average molecular weight Mn of polymer)
The weight average molecular weight Mw and number average molecular weight Mn of the polymer were measured as polystyrene equivalent values using a gel permeation chromatography (GPC) system ("HLC-8320" manufactured by Tosoh Corporation). During the measurement, an H-type column (manufactured by Tosoh Corporation) was used as the column, and tetrahydrofuran was used as the solvent. The column temperature during the measurement was 40°C.

(Method for measuring hydrogenation rate of polymer)
The hydrogenation rate of the polymer was measured by ¹ H-NMR measurement at 145° C. using orthodichlorobenzene- _d4 as a solvent.

(Glass transition temperature Tg and melting point Tm)
The polymer was melted by heating and then quenched with dry ice. Subsequently, the glass transition temperature Tg and melting point Tm of the polymer were measured using a differential scanning calorimeter (DSC) at a heating rate of 10°C/min (heating mode).

(Ratio of racemo-dyad in hydrogenated ring-opening polymer)
Using orthodichlorobenzene-d ₄ /1,2,4-trichlorobenzene (TCB)-d ₃ (mixing ratio (by mass) 1/2) as the solvent, ¹³ C-NMR measurements were performed at 200°C using the inverse-gated decoupling method to determine the proportion of racemo dyads. Specifically, using the peak of 127.5 ppm of orthodichlorobenzene-d ₄ as the reference shift, a signal at 43.35 ppm derived from meso dyads and a signal at 43.43 ppm derived from racemo dyads were identified. The proportion of racemo dyads was determined based on the intensity ratio of these signals.

(film thickness)
The thickness of the film was measured using a contact type thickness meter (manufactured by MITUTOYO Corporation, Code No. 543-390).

(Thermal shrinkage rate)
To measure the thermal shrinkage (pFs and pFp) of the substrate and protective film before annealing, each film was cut out at 23°C (room temperature) to obtain a square sample film measuring 120 mm x 120 mm. To measure the thermal shrinkage (Fs and Fp) of the substrate and protective film, which are layers of the laminate after annealing, the laminate was cut out at 23°C (room temperature) to obtain a square piece measuring 120 mm x 120 mm, and the substrate and composite film were peeled off to obtain a sample film. Because the effect of the adhesive layer on the thermal shrinkage was negligibly small, the thermal shrinkage of the protective film was measured in the state of a composite film with the adhesive layer attached. Each side of the square sample film was parallel to the longitudinal or transverse direction of the film.

This sample film was heated under specified heating conditions, then cooled to 23°C (room temperature), and the lengths of all four sides of the sample film were measured. For measurements of the pre-annealed substrate and pre-annealed protective film, two heating conditions were used: 145°C for 60 minutes and 200°C for 10 minutes. For measurements of the annealed substrate and protective film, the heating condition was 180°C for 2 minutes. For measurements of the annealed substrate, measurements were also performed at 145°C for 60 minutes and 200°C for 10 minutes.

The heat shrinkage of the sample film was calculated based on the measured lengths of each of the four sides according to the following formula (I): In formula (I), L _B represents the length of the side of the sample film before heating, and in this measurement, L _B was 120 mm, and L _A represents the length of the side of the sample film after heating.
Heat shrinkage rate (%) = [(L _B - L _A ) / L _B ] × 100 (I)
A positive value of the heat shrinkage rate indicates that the film shrinks when heated, and a negative value indicates that the film expands when heated.

The average value of the shrinkage rates of the two sides along the film's conveying direction (i.e., the longitudinal direction of the long film) was used as the thermal shrinkage rate in the film's conveying direction, i.e., the thermal shrinkage rate in the longitudinal direction of the long film. Furthermore, the average value of the thermal shrinkage rates of the two sides along the film's width direction was used as the thermal shrinkage rate in the width direction of the long film. Furthermore, for the substrate and protective film after annealing, the value of Fs - Fp was calculated from the thermal shrinkage rate Fs (%) in the longitudinal direction of the substrate and the thermal shrinkage rate Fp (%) in the longitudinal direction of the protective film.

(Elastic Modulus)
The laminate after annealing was cut out in an environment of 23°C (room temperature) to obtain rectangular pieces measuring 20 mm in length and 5 mm in width, and the substrate and composite film were peeled off to obtain sample films. Since the influence of the adhesive layer on the elastic modulus was negligibly small, the elastic modulus of the protective film was measured in the state of the composite film with the adhesive layer. The lengthwise side of the rectangular sample film was parallel to the longitudinal direction of the long laminate.
Stretching viscoelasticity measurements were performed using a dynamic viscoelasticity measuring device (Hitachi High-Tech Science Corporation, product name: DMA7100) at a frequency of 1 Hz, a heating rate of 5°C per minute, and a temperature range of 25 to 220°C, and the storage moduli E's and E'p at 180°C were used.

(Smoothness of the plane)
The laminate after annealing was cut into a 300 mm × 300 mm square piece, and the substrate and the protective film were peeled off. The substrate was spread on a horizontal, flat table, and the surface smoothness of the substrate was visually evaluated according to the following criteria.
Good: No corrugated wrinkles with streaks along the conveying direction, no practical problems.
Fair: There are a few corrugated wrinkles with streaks along the conveying direction, but this does not pose a problem in practical use.
Unacceptable: Corrugated wrinkles with streaks along the conveying direction were observed, which was problematic for practical use.

(Amount of curl of laminate after annealing treatment)
The laminate after annealing was cut out in an environment of 23°C (room temperature) to obtain a 50 mm x 50 mm square sample film. The sample film was placed on a horizontal, flat table. When placing the sample film, the side that appeared to have shrunk and formed a concave shape was placed on top. The amount by which the four corners of the sample film were lifted from the table top (curl amount) was measured with a ruler, and the average value of the four corners was taken as the curl amount of the sample film.

(Crystallization degree)
The crystallinity of the pre-annealed substrate and the pre-annealed protective film was measured by the following method using sample films cut out of an appropriate size.
The crystallinity of each layer of the laminate, i.e., the substrate and the protective film, after the annealing treatment was measured by cutting the laminate to an appropriate size, peeling off the substrate and the protective film, wiping off the adhesive layer attached to the protective film with an organic solvent such as methyl ethyl ketone, and thoroughly drying the resulting sample film using the following method.

(Degree of crystallinity of base film/PET film)
The density of the sample film was measured using a helium gas displacement dry automatic density meter "AccuPyc 1340" (Micromeritics). Approximately 3 g of the sample film was cut into strips with a width of 30 mm or less, rolled up, and placed in a ^{10 cm3} container, which was maintained at 25°C for measurement. The density was determined from 10 repeated measurements.

The crystallinity x (%) was calculated by the following formula:
x=(1/Da-1/D)/(1/Da-1/Dc)×100
In the above formula, x represents the degree of crystallinity. D (g/cm ³ ) represents the determined density of the sample film. Da represents the completely amorphous density (g/cm ³ ) of the polymer forming the sample film. Db represents the completely crystalline density (g/cm ³ ) of the polymer forming the sample film.

The following value was used as the completely amorphous density Da.
The completely amorphous density Da of the hydrogenated dicyclopentadiene ring-opening polymer produced in Production Example 1 was 1.0157 g/cm ³
Completely amorphous density of polyethylene terephthalate (PET) Da = 1.335 g/cm ³

The following value was used as the perfect crystal density Dc.
The perfect crystal density Dc of the hydrogenated dicyclopentadiene ring-opening polymer produced in Production Example 1 = 1.0857 g/cm ³
・Completely crystalline density of PET Dc = 1.455 g / cm ³

(Crystallization degree of SPS film)
Using a differential scanning calorimeter (DSC), the crystallization enthalpy and fusion enthalpy were measured when the sample film was heated from 50° C. to 300° C. at a heating rate of 20° C./min, and calculated according to the following formula.
Crystallinity (%)={[melting enthalpy (J/g)−crystallization enthalpy (J/g)]/melting enthalpy (J/g) at 100% crystallinity}×100
Here, 53 J/g was used as the melting enthalpy (J/g) when the crystallinity was 100%.

(Crystallization degree of polyamide film)
The crystallinity of the sample film, which was a polyamide film, was measured by X-ray diffraction.

[Production Example 1: Crystalline Resin]
A metal pressure reactor was thoroughly dried and then purged with nitrogen, and then 154.5 parts of cyclohexane, 42.8 parts of a 70% cyclohexane solution of dicyclopentadiene (endo isomer content of 99% or more) (30 parts as the amount of dicyclopentadiene), and 1.9 parts of 1-hexene were placed in the metal pressure reactor, and the mixture was heated to 53°C.

A solution was prepared by dissolving 0.014 parts of tetrachlorotungsten phenylimide (tetrahydrofuran) complex in 0.70 parts of toluene. 0.061 parts of a 19% diethylaluminum ethoxide/n-hexane solution was added to this solution and stirred for 10 minutes to prepare a catalyst solution. This catalyst solution was placed in a pressure-resistant reactor to initiate the ring-opening polymerization reaction. The reaction was then continued for 4 hours while maintaining the temperature at 53°C, yielding a solution of a ring-opened polymer of dicyclopentadiene. The number-average molecular weight (Mn) and weight-average molecular weight (Mw) of the resulting ring-opened polymer of dicyclopentadiene were 8,750 and 28,100, respectively, and the molecular weight distribution (Mw/Mn) calculated from these values was 3.21.

0.037 parts of 1,2-ethanediol as a terminator was added to 200 parts of the resulting solution of ring-opened dicyclopentadiene polymer, and the mixture was heated to 60°C and stirred for 1 hour to terminate the polymerization reaction. One part of a hydrotalcite-like compound (Kyoward® 2000, manufactured by Kyowa Chemical Industry Co., Ltd.) was then added, heated to 60°C, and stirred for 1 hour. 0.4 parts of a filter aid (Radiolite® #1500, manufactured by Showa Chemical Industry Co., Ltd.) was then added, and the adsorbent and solution were filtered using a PP pleated cartridge filter (TCP-HX, manufactured by ADVANTEC Toyo Co., Ltd.).

100 parts of cyclohexane were added to 200 parts of the filtered dicyclopentadiene ring-opening polymer solution (30 parts polymer), and 0.0043 parts of chlorohydridocarbonyltris(triphenylphosphine)ruthenium was added. The hydrogenation reaction was carried out at 180°C under a hydrogen pressure of 6 MPa for 4 hours. This yielded a reaction solution containing the hydride of the dicyclopentadiene ring-opening polymer. The hydride precipitated from this reaction solution, forming a slurry solution.

The reaction mixture was separated from the hydride and the solution using a centrifuge and then dried under reduced pressure at 60°C for 24 hours to yield 28.5 parts of a crystalline hydrogenated ring-opening polymer of dicyclopentadiene. The hydrogenation rate of this product was over 99%, the glass transition temperature (Tg) was 93°C, the melting point (Tm) was 267°C, and the racemo-dyad ratio was 89%.

100 parts of the resulting hydrogenated ring-opening polymer of dicyclopentadiene was mixed with 1.1 parts of an antioxidant (tetrakis[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane; "Irganox (registered trademark) 1010" manufactured by BASF Japan Ltd.), and then the mixture was fed into a twin-screw extruder (product name "TEM-37B" manufactured by Toshiba Machine Co., Ltd.) equipped with four die holes with an inner diameter of 3 mm. The mixture of the hydrogenated ring-opening polymer of dicyclopentadiene and the antioxidant was formed into strands by hot-melt extrusion molding, and then chopped with a strand cutter to obtain a pellet-shaped crystalline resin (Resin A). The operating conditions for the twin-screw extruder were as follows:

・Barrel setting temperature = 270-280℃
Die set temperature = 250°C
・Screw rotation speed = 145 rpm

Example 1
(1-1. Base material before annealing)
100 parts of Resin A produced in Production Example 1 was mixed with 0.05 parts of an antiblocking agent (silica particles, manufactured by Admatechs Co., Ltd., product name: "Adma Fine Silica SC4053-SQ"), and then molded using a hot melt extrusion film molding machine equipped with a T-die to obtain a long extruded film (thickness: 500 μm) with a width of approximately 1200 mm. The operating conditions of the film molding machine were as follows:
・Barrel setting temperature = 280℃ to 300℃
Die temperature = 270°C
Casting roll temperature = 80°C

The extruded film was fed into a simultaneous biaxial stretching machine and subjected to the simultaneous biaxial stretching process. The stretching ratio was 3.5 times in the longitudinal direction and 2.9 times in the transverse direction, and the stretching temperature was 115°C. After the stretching process, the film was subjected to a crystallization promotion process. Crystallization promotion was performed by holding the film in the stretching machine and heating it to a temperature of 240°C for 15 seconds, reducing the film dimensions to 0.94 times in the longitudinal direction and 0.96 times in the transverse direction. After the crystallization promotion process, the film was cooled to a temperature of 100°C or below, and both ends of the film in the transverse direction were slit to obtain a pre-annealed substrate as a long film with a width of 1,100 mm. The thermal shrinkage, film thickness, and crystallinity of the resulting pre-annealed substrate were measured.

(1-2. Composite Film Including Protective Film Before Annealing)
A commercially available 35 μm-thick syndiotactic polystyrene (SPS) film (manufactured by Kurabo Industries, Ltd., product name "Oidys® HNL") was pulled out from a film roll and subjected to a discharge treatment (corona treatment) on one side. The discharge treatment was performed using a corona treatment device (manufactured by Kasuga Electric Co., Ltd.) under the following discharge conditions: output power 500 W, electrode length 1.35 m, and conveying speed 10 m/min.

An acrylic adhesive (Fujimori Kogyo's "Masterc Series") was applied to the discharge-treated surface of the film using a die coater to a dry film thickness of 10 μm, and the film was then passed through a drying oven at 100°C to dry the adhesive. This resulted in a composite film comprising an SPS film protective film and an adhesive layer formed on one surface of the SPS film, in the form of a long film measuring 1,100 mm in width. The thermal shrinkage and crystallinity of the protective film before annealing were measured.

(1-3. Laminate before annealing)
One surface of the pre-annealed substrate obtained in (1-1) and the surface of the adhesive layer side of the composite film obtained in (1-2) were aligned in the longitudinal direction and bonded together using a nip roll to produce a long pre-annealed laminate comprising the pre-annealed substrate and the pre-annealed protective film.

(1-4. Laminate)
The pre-annealed laminate obtained in (1-3) was transported in the longitudinal direction, continuously introduced into a dryer, and heated, thereby carrying out an annealing treatment. A roll-support type dryer was used as the dryer. This dryer was equipped with an upstream nip roll, a downstream nip roll, and an oven installed therebetween. By adjusting the peripheral speed ratio between the upstream nip roll and the downstream nip roll, a long film was transported while applying tension to the film between the nip rolls, and passed through the oven between them. In the oven, the film was guided only by a non-constraining roll supporting the film from below, thereby allowing the film to be heated in the oven without being constrained in the film width direction. The heating temperature in the annealing treatment was 200°C, the heating time was 2 minutes, and the transport tension was 13 N. As a result of this annealing treatment, a laminate including a substrate and a protective film was obtained.

(1-5. Evaluation)
The laminate obtained in (1-4) was evaluated for the modulus of elasticity of each layer, the heat shrinkage rate of each layer, the crystallinity of each layer, the surface smoothness, and the amount of curl.

Example 2
A laminate was obtained and evaluated in the same manner as in Example 1, except for the following changes.
In the preparation of the composite film including the pre-annealed protective film (1-2), a 75 μm thick SPS film (manufactured by Kurabo Industries, Ltd., product name "Oidys (registered trademark) CN") was used instead of the 35 μm thick SPS film.

Example 3
A laminate was obtained and evaluated in the same manner as in Example 1, except for the following changes.
In the preparation of the pre-annealed substrate (1-1), the dimensions of the T-die opening and the operating conditions of the molding machine were changed, and the thickness of the extruded film was changed to 430 μm. Furthermore, the stretching ratio was changed from 3.5 times to 2.6 times in the longitudinal direction and from 2.9 times to 3.3 times in the width direction. However, the reduction ratio in the crystallization promotion step was unchanged from Example 1. The width dimension of the obtained pre-annealed substrate was also 1100 mm, unchanged from Example 1.

Example 4
A laminate was obtained and evaluated in the same manner as in Example 1, except for the following changes.
In the preparation of the pre-annealed substrate (1-1), the dimensions of the opening of the T-die and the operating conditions of the molding machine were changed, and the thickness of the extruded film was changed to 1000 μm.

Example 5
(5-1. Base material before annealing)
Resin A produced in Production Example 1 was molded using a hot melt extrusion film molding machine equipped with a T-die to obtain a long extruded film (thickness 48 μm) with a width of approximately 1,350 mm. The operating conditions of the film molding machine were as follows.
・Barrel setting temperature = 280℃ to 300℃
Die temperature = 270°C
Casting roll temperature = 80°C

The extruded film was fed into a transverse stretching machine using a tenter and subjected to fixed-end uniaxial stretching. The stretching ratio was 1.0x in the longitudinal direction and 1.35x in the transverse direction. Prior to stretching, the extruded film was preheated to a temperature of 120°C and then stretched at a temperature of 140°C. After the stretching process, the film was subjected to a crystallization promotion process. Crystallization promotion was performed by conveying the film in the stretching machine while holding it and maintaining its dimensions unchanged, and heating the film to a temperature of 160°C for 30 seconds. After the crystallization promotion process, the film was cooled to a temperature of 100°C or below, and both widthwise ends of the film were slit to obtain a pre-annealed substrate as a long film with a width of 1100 mm. The thermal shrinkage, film thickness, and crystallinity of the resulting pre-annealed substrate were measured.

(5-2. Composite Film Including Protective Film Before Annealing)
A commercially available PET film (manufactured by Toray Industries, Inc., product name "Lumirror S10," thickness 125 μm) was unwound from a film roll and subjected to a discharge treatment (corona treatment) on one side. The discharge treatment was performed using a corona treatment device (manufactured by Kasuga Electric Co., Ltd.) under the following discharge conditions: output power 500 W, electrode length 1.35 m, and conveying speed 10 m/min.

An acrylic adhesive (Fujimori Kogyo's "Masterc Series") was applied to the discharge-treated surface of the film using a die coater to a dry film thickness of 10 μm, and the film was then passed through a drying oven at 100°C to dry the adhesive. This resulted in a composite film comprising a PET protective film and an adhesive layer formed on one surface of the protective film, in the form of a long film 1,100 mm wide. The thermal shrinkage and crystallinity of the resulting protective film before annealing were measured.

(5-3. Laminate before annealing)
One surface of the pre-annealed substrate obtained in (5-1) and the surface of the adhesive layer side of the composite film obtained in (5-2) were aligned in the longitudinal direction and bonded together using a nip roll to produce a long pre-annealed laminate comprising the pre-annealed substrate and the pre-annealed protective film.

(5-4. Laminate)
The pre-annealed laminate obtained in (5-3) was transported in the longitudinal direction, continuously introduced into a dryer, and heated, thereby carrying out an annealing treatment. A transverse stretching machine was used as the dryer, and the film was conveyed and heated while being held in the stretching machine and maintaining the dimensions of the film in the longitudinal and width directions unchanged. The heating temperature in the annealing treatment was 170°C, and the heating time was 5 minutes. As a result of this annealing treatment, a laminate including a substrate and a protective film was obtained.

(5-5. Evaluation)
The laminate obtained in (5-4) was evaluated for the modulus of elasticity of each layer, the heat shrinkage rate of each layer, the crystallinity of each layer, the surface smoothness, and the amount of curl.

Example 6
A laminate was obtained and evaluated in the same manner as in Example 5, except for the following changes.
In the preparation of the pre-annealed substrate (5-1), the dimensions of the T-die opening and the operating conditions of the molding machine were changed, and the thickness of the extruded film was changed to 42 μm. Furthermore, the stretching ratio in the width direction was changed from 1.35 times to 1.2 times (the longitudinal direction was unchanged at 1.0 times). However, the reduction ratio in the crystallization promotion step was unchanged from Example 5. The width dimension of the obtained pre-annealed substrate was also 1100 mm, unchanged from Example 1.

Comparative Example 1
Except for the following changes, laminates were obtained and evaluated in the same manner as in (1-1) and (1-3) to (1-5) of Example 1.
In (1-3), the composite film including the pre-annealed protective film obtained in (5-2) of Example 5 was used instead of the one obtained in (1-2).

Comparative Example 2
A laminate was obtained in the same manner as in Example 1, except for the following changes.
In the preparation of the composite film including the pre-annealed protective film (1-2), a commercially available film of a polymer containing an alicyclic structure (manufactured by Zeon Corporation, trade name "ZeonorFilm (trademark) ZF16", thickness 146 μm) was used instead of the 35 μm-thick SPS film.

We attempted to evaluate the resulting laminate, but the substrate and protective film could not be peeled apart, making it impossible to evaluate.

Comparative Example 3
(C3-1. Composite film including protective film before annealing)
Polyamide pellets (manufactured by Daicel-Eponic Co., Ltd., product name "Trogamid CX7323") were molded using a hot melt extrusion film molding machine equipped with a T-die to obtain a long extruded film (thickness 118 μm) with a width of approximately 1100 mm. The operating conditions of the film molding machine were as follows:
・Barrel setting temperature = 260℃ to 280℃
Die temperature = 250°C
Casting roll temperature = 110°C

The extruded film was heat-treated using a roll-support dryer. The heating temperature was 180°C, and the heating time was 5 minutes. After the heat treatment, one side of the film was subjected to a discharge treatment (corona treatment). A corona treatment device (manufactured by Kasuga Electric Co., Ltd.) was used for the discharge treatment, and the discharge conditions were an output of 500 W, an electrode length of 1.35 m, and a conveying speed of 10 m/min.

An acrylic adhesive (Fujimori Kogyo's "Masterc Series") was applied to the discharge-treated surface of the film using a die coater to a dry film thickness of 10 μm, and the film was then passed through a drying oven at 100°C to dry the adhesive. This resulted in a composite film comprising a polyamide film protective film and an adhesive layer formed on one surface of the protective film, in the form of a long film 1100 mm wide. The thermal shrinkage and crystallinity of the resulting protective film before annealing were measured.

(C3-2. Laminate)
Except for the following changes, laminates were obtained and evaluated in the same manner as in (1-1) and (1-3) to (1-5) of Example 1.
In (1-3), the composite film including the pre-annealed protective film obtained in (C3-1) was used instead of the one obtained in (1-2).

Comparative Example 4
A laminate was obtained and evaluated in the same manner as in Example 1, except for the following changes.
In the preparation of the composite film including the pre-annealed protective film of (1-2), the same pre-annealed substrate as obtained in (1-1) was used instead of the 35 μm-thick SPS film. That is, in (1-2), a long composite film including the pre-annealed substrate obtained in (1-1) and an adhesive layer formed on one surface thereof was prepared, and this was used to carry out the steps from (1-3) onwards.

Comparative Example 5
Without using a composite film containing a pre-annealing protective film, the pre-annealing substrate obtained in (1-1) of Example 1 was directly subjected to the steps of Example (1-4) and thereafter and evaluated.

The results of the examples and comparative examples are shown in Tables 1 to 4.

As is clear from the above results, in the present examples, the occurrence of wrinkles in the laminate was suppressed, the flatness of the substrate peeled from the laminate was maintained, and the heat resistance indicators of the substrate, such as the heat shrinkage rate at 200°C for 10 minutes and the heat shrinkage rate at 145°C for 60 minutes, were all better than in the comparative examples. This demonstrates that the laminate of the present invention makes it possible to easily supply substrates with high flatness and heat resistance when needed.

10: Laminate 110: Substrate 120: Composite film 121: Protective film 122: Adhesive layer

Claims (7)

A laminate having a long shape, comprising a substrate and a protective film provided on one surface of the substrate,
the substrate is a layer of a resin containing a crystalline alicyclic structure-containing polymer,
A laminate, wherein the substrate and the protective film satisfy the following formulas (1) and (2):
E's/E'p<1 (1)
−0.4≦Fs−Fp≦0.4 (2)
however,
E's is the storage modulus of the substrate at 180°C,
E'p is the storage modulus of the protective film at 180°C,
Fs is the heat shrinkage rate (%) of the substrate in the longitudinal direction of the laminate at 180°C for 2 minutes,
Fp is the heat shrinkage rate (%) of the protective film in the longitudinal direction of the laminate at 180° C. for 2 minutes. The laminate described in claim 1, wherein the protective film is a layer of a resin containing a crystalline polymer. A laminate according to claim 1 or 2, wherein the resin containing the crystalline alicyclic structure-containing polymer constituting the substrate is a hydrogenated product of a ring-opening polymer of dicyclopentadiene. A method for producing the laminate according to any one of claims 1 to 3,
A manufacturing method comprising: a step of laminating a pre-annealed substrate and a pre-annealed protective film to obtain a pre-annealed laminate comprising the pre-annealed substrate and the pre-annealed protective film, wherein the pre-annealed substrate is a layer of a resin containing a crystalline alicyclic structure-containing polymer; and a step of annealing the pre-annealed laminate. The manufacturing method described in claim 4, wherein the pre-annealed protective film is a layer of resin containing a crystalline polymer. The manufacturing method described in claim 4 or 5, wherein the resin containing the crystalline alicyclic structure-containing polymer that constitutes the pre-annealed substrate is a hydrogenated product of a ring-opening polymer of dicyclopentadiene. A manufacturing method described in any one of claims 4 to 6, wherein the annealing treatment includes heating the pre-annealed laminate while restraining it in at least one of its in-plane directions.