Laminate, transparent conductive film, and method for manufacturing transparent conductive film

Abstract

To provide a laminate which has a heat-resistant resin layer having high optical characteristics, and can suppress occurrence of curling accompanying heating treatment.SOLUTION: A laminate has a process film, and a heat-resistant resin layer in this order, wherein a storage elastic modulus at 80°C of the heat-resistant resin layer is 0.01-100 GPa, thickness of the heat-resistant resin layer is 20 μm or less, and a dimensional change rate in MD by heating at 150°C for one hour of the process film is 0.5% or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a laminate, a transparent conductive film using the same, and a method for producing a transparent conductive film. [Background technology]

[0002] In recent years, in order to realize thinner, lighter, more flexible, and more efficient electronic devices for optical applications, including display devices such as liquid crystal displays and organic electroluminescence (EL) displays, the use of thin, transparent plastic films as substrates for components constituting electronic devices has been considered, instead of conventional rigid substrates such as glass. However, plastic films generally have poorer heat resistance than glass. For example, a transparent plastic film may be used as a substrate for forming a transparent conductive layer of an electronic device. In this case, the substrate is required to have excellent optical properties at the same level as an optical film, and also to have excellent heat resistance against high-temperature heat treatment for the conductive layer, etc., in the transparent conductive layer formation process.

[0003] Furthermore, in the case of gas barrier films used as components for electronic devices such as various displays, it has been proposed to form a gas barrier layer having properties that inhibit the transmission of water vapor and oxygen on a layer of a cured product of a curable resin composition (cured resin layer). For example, Patent Document 1 discloses a gas barrier laminate that is provided on the display surface side of a display device or the like together with a transparent conductive layer, and that has a configuration in which a processing film such as a polyethylene terephthalate (PET) film, a base layer, and a gas barrier layer are arranged in this order.The patent document also describes that a cured resin layer is formed as the base layer on the processing film. When a curable resin composition is applied to a process film and cured to form a cured resin layer on the process film, the cured resin layer exhibits a high elastic modulus even at high temperatures and can be made thin, resulting in improved optical properties and gas barrier properties. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2020 / 138206 Summary of the Invention [Problem to be solved by the invention]

[0005] The optical film having a transparent conductive layer formed on the transparent plastic film and the gas barrier film described above require high optical properties and high gas barrier properties. Therefore, they are required to be thin and to be manufactured so as to exhibit a high elastic modulus even at high temperatures. In addition, they are required to exhibit excellent dimensional stability against high-temperature heat treatment when forming functional layers such as a conductive layer and a gas barrier layer. When a PET film is used as a processing sheet corresponding to the support layer of the gas barrier layer, as in the gas barrier laminate described in Patent Document 1, the PET film shrinks after high-temperature heat treatment, for example, at 150°C for 1 hour, causing curling of the laminate including the cured resin layer. This reduces handleability in subsequent processes. Furthermore, when a composite is obtained by transferring the cured resin layer to an adherend using an adhesive after the gas barrier layer has been formed, the composite also curls due to residual stress.

[0006] In view of the above problems, an object of the present invention is to provide a laminate including a heat-resistant resin layer having high optical properties and capable of suppressing curling due to heat treatment. Another object of the present invention is to provide a transparent conductive film including the laminate, and a method for producing the same. [Means for solving the problem]

[0007] As a result of extensive research into solving the above-mentioned problems, the present inventors have found that the above-mentioned problems can be solved by providing a laminate having a process sheet and a heat-resistant resin layer in this order, in which the heat-resistant resin layer has a predetermined thickness and a predetermined storage modulus, and further, the process sheet has a predetermined dimensional change rate when heated under predetermined conditions, and have thus completed the present invention. That is, the present invention provides the following [1] to [6]. [1] A casting film and a heat-resistant resin layer (A) are provided in this order, the heat-resistant resin layer (A) has a storage modulus at 80°C of 0.01 to 100 GPa; The thickness of the heat-resistant resin layer (A) is 20 μm or less, A laminate in which the dimensional change rate of the cast film in MD when heated at 150°C for 1 hour is 0.5% or less. [2] The laminate according to the above [1], wherein the heat-resistant resin layer (A) is a layer made of a cured product of a curable resin composition (C1) containing a polymer component (M) that is a polyimide resin and a curable monomer (P). [3] The casting film has a first surface facing the heat-resistant resin layer (A), The laminate according to the above [1] or [2], wherein the first surface is peelable from the heat-resistant resin layer (A) and has a peel strength of 500 mN / 50 mm or less after heating at 150°C for 1 hour. [4] The laminate according to [1] or [2] above, further comprising a functional layer located on the surface of the heat-resistant resin layer (A) opposite to the surface facing the casting film. [5] A transparent conductive film comprising the laminate according to [1] or [2] above and a transparent conductive layer provided on the heat-resistant resin layer (A) of the laminate. [6] A method for producing a transparent conductive film, comprising: forming a conductive material layer on the heat-resistant resin layer (A) of the laminate according to [1] or [2] above; and heating the conductive material layer to 100°C or higher to form a transparent conductive layer. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a laminate including a heat-resistant resin layer having high optical properties and capable of suppressing curling due to heat treatment. The present invention also provides a transparent conductive film including the laminate and a method for producing the same. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a cross-sectional view showing an example of a laminate of the present invention. [Figure 2] FIG. 2 is a cross-sectional view showing another example of the laminate of the present invention. [Figure 3] FIG. 2 is a cross-sectional view showing another example of the laminate of the present invention. [Figure 4] FIG. 2 is a cross-sectional view showing another example of the laminate of the present invention. [Figure 5] FIG. 2 is a cross-sectional view showing another example of the laminate of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] In this specification, preferred definitions can be selected arbitrarily, and combinations of preferred definitions can be considered more preferred. In this specification, the expression "XX to YY" means "XX or more and YY or less." In this specification, for preferred numerical ranges (e.g., ranges of content, etc.), the lower and upper limits described in stages can be independently combined. For example, the description "preferably 10 to 90, more preferably 30 to 60" can be combined with the "preferable lower limit (10)" and the "more preferable upper limit (60)" to form "10 to 60." In this specification, for example, "(meth)acrylic acid" refers to both "acrylic acid" and "methacrylic acid," and the same applies to other similar terms.

[0011] [Laminate] The laminate of the present invention comprises a casting film and a heat-resistant resin layer (A) in this order, wherein the heat-resistant resin layer (A) has a storage modulus at 80°C of 0.01 to 100 GPa, the heat-resistant resin layer (A) has a thickness of 20 μm or less, and the casting film has a dimensional change rate in MD of 0.5% or less when heated at 150°C for 1 hour. In the above laminate, by setting the storage modulus of the heat-resistant resin layer (A) at 80°C to 0.01 to 100 GPa, sufficient heat resistance is ensured in the heat-resistant resin layer (A), and deformation, etc. can be prevented even when the laminate is subjected to high-temperature heat treatment (e.g., 150°C, 1 hour). Furthermore, by setting the thickness of the heat-resistant resin layer (A) to 20 μm or less, the optical properties of the heat-resistant resin layer (A) can be improved. Furthermore, by ensuring that the dimensional change rate of the process film in the MD after heating at 150°C for 1 hour is 0.5% or less, curling due to high-temperature heat treatment can be suppressed. MD refers to the direction of flow of the raw roll when the process film is produced. The MD of the process film usually has a higher residual stress than the CD, which is the width direction of the raw roll. Therefore, by using, for example, an annealed resin film as the process film, the dimensional change rate of the process film in the MD can be kept to 0.5% or less, effectively suppressing curling of the laminate due to heat treatment. As a result, the laminate can have a heat-resistant resin layer (A) with high optical properties and can suppress the occurrence of curling due to heat treatment, thereby solving the above-mentioned problems.

[0012] The storage modulus at 80°C of the heat-resistant resin layer (A) is measured by peeling and removing the processing film from the laminate, laminating the required number of sheets to prepare a test piece of a predetermined size, and using a thermomechanical analyzer to raise the temperature of the test piece at a predetermined heating rate while holding it, and examining the storage modulus at 80°C. The dimensional change rate of the processing film is measured in accordance with JIS K7133 (1999) by heating a test piece of a predetermined size at 150°C for 2 hours. More specifically, these physical property values ​​are measured by the methods described in the Examples.

[0013] Fig. 1 is a cross-sectional view showing an example of the laminate of the present invention. The laminate 1 shown in Fig. 1 is composed of a heat-resistant resin layer (A) 2 and a casting film 3 arranged in this order. As described below, a heat-resistant resin layer (A) 2 can be provided directly on the surface of the casting film 3 by applying a curable resin composition to the casting film 3 and curing the applied layer to form a cured layer. This allows for a thin heat-resistant resin layer (A) 2. Furthermore, an intervening layer such as a pressure-sensitive adhesive layer is not required, simplifying the structure of the laminate and eliminating adhesive residue when the casting film is peeled off after high-temperature heat treatment. Eliminating the need for an intervening layer also has the advantage of making it easier to improve optical performance.

[0014] In the laminate, the cast film preferably has a first surface facing the heat-resistant resin layer (A), and the first surface is peelable from the heat-resistant resin layer (A) and has a peel strength of 500 mN / 50 mm or less after heating at 150°C for 1 hour. If the casting film has the above-described structure, the thin heat-resistant resin layer can be easily peeled off from the casting film without being damaged even after heat treatment. The casting film may have a release layer, in which case the laminate has a configuration in which a release layer is further provided between the heat-resistant resin layer (A) and the casting film substrate. Fig. 2 is a cross-sectional view showing another example of the laminate of the present invention. The laminate 11 shown in Fig. 2 is composed of a heat-resistant resin layer (A) 2, and a casting film 3 having a release layer 3a and a casting film substrate 3b, arranged in this order.

[0015] From the above viewpoints, the peel strength between the heat-resistant resin layer (A) and the process film or release layer after heating at 150°C for 1 hour is more preferably 400 mN / 50 mm or less, even more preferably 300 mN / 50 mm or less, and particularly preferably 250 mN / 50 mm or less.

[0016] The peel strength between the heat-resistant resin layer (A) and the process film or release layer after heating at 150°C for 1 hour is preferably 20 mN / 50 mm or more, more preferably 50 mN / 50 mm or more, even more preferably 100 mN / 50 mm or more, and particularly preferably 150 mN / 50 mm or more.

[0017] From the same viewpoints as above, the peel strength between the heat-resistant resin layer (A) and the process film or release layer before heating at 150°C for 1 hour is preferably 20 to 500 mN / 50 mm, more preferably 50 to 400 mN / 50 mm, even more preferably 100 to 300 mN / 50 mm, and even more preferably 150 to 250 mN / 50 mm.

[0018] When the peel strength between the heat-resistant resin layer (A) and the process film or the release layer is within the above range, the process film is less likely to peel off during web handling, and the heat-resistant resin layer (A) can be easily peeled off from the process film both before and after heat treatment. The peel strength was measured by the method described in the Examples section below.

[0019] The peel strength between the heat-resistant resin layer (A) and the process film or the release layer can be set within the above range, for example, by selecting the material of the process film or the material of the release layer provided on the process film from those having excellent heat resistance and release properties.

[0020] The thickness of the laminate, including the functional layer described below, can be appropriately determined depending on the intended use of the adherend, electronic device, etc. From the viewpoint of handleability, the thickness of the laminate is preferably 5 to 300 μm, more preferably 10 to 200 μm, and even more preferably 20 to 100 μm.

[0021] The laminate may further comprise a functional layer located on the surface of the heat-resistant resin layer (A) opposite to the surface facing the casting film. Figures 3 and 4 are cross-sectional views showing other examples of the laminate of the present invention. Laminate 21 shown in Figure 3 has a configuration in which a functional layer 5, a heat-resistant resin layer (A) 2, and a processing film 3 are arranged in this order. Laminate 31 shown in Figure 4 has a configuration in which a functional layer 5, a heat-resistant resin layer (A) 2, and a processing film 3 having a release layer 3a and a processing film substrate 3b are arranged in this order. When the functional layer 5 is laminated on the heat-resistant resin layer (A) 2, as in laminates 21 and 31, laminates 21 and 31 function as a support layer or substrate that supports the functional layer 5 during and after its formation. The functional layer is, for example, a transparent conductive layer or a gas barrier layer. When the functional layer is a transparent conductive layer, the laminate becomes a transparent conductive film. When the functional layer is a gas barrier layer, the laminate becomes a gas barrier film. Details of the functional layer will be described later.

[0022] The laminate may have a second heat-resistant resin layer (heat-resistant resin layer (B)) on the surface of the casting film opposite to the surface facing the heat-resistant resin layer (A). Fig. 5 is a cross-sectional view showing another example of the laminate of the present invention. The laminate 41 shown in Fig. 5 is composed of a heat-resistant resin layer (A) 2, a casting film 3, and a heat-resistant resin layer (B) 4 arranged in this order. By providing the heat-resistant resin layer (B) 4 on the surface of the casting film 3 opposite to the surface on which the heat-resistant resin layer (A) 2 is located, it becomes easier to prevent oligomer components from precipitating from the casting film 3 into the heat-resistant resin layer (B) 4 due to long-term heat treatment at high temperatures, and it also becomes easier to prevent oligomer components from precipitating into the heat-resistant resin layer (A) 2. This prevents an increase in the haze value of the laminate 41, and naturally, the same applies to the heat-resistant resin layer (A) 2 after the casting film is peeled off. In the laminates 11, 21, and 31 shown in FIGS. 2 to 4, a heat-resistant resin layer (B) 4 may also be provided on the surface of the casting film 3 opposite to the surface on which the heat-resistant resin layer (A) 2 is formed.

[0023] <Heat-resistant resin layer (A)> The heat-resistant resin layer (A) contained in the laminate has a storage modulus at 80° C. of 0.01 to 100 GPa, and the heat-resistant resin layer (A) has a thickness of 20 μm or less. When the storage modulus of the heat-resistant resin layer (A) at 80°C is 0.01 GPa or more, the necessary heat resistance can be ensured, and when it is 100 GPa or less, excessive stress generated during rolling, etc. can be suppressed, and scratches on the heat-resistant resin layer can be prevented. From the above viewpoints, the storage modulus of the heat-resistant resin layer (A) at 80° C. is preferably 0.1 to 70 GPa, more preferably 0.5 to 50 GPa, even more preferably 1 to 30 GPa, and still more preferably 1.5 to 10 GPa. When the thickness of the heat-resistant resin layer (A) is 20 μm or less, the bending resistance is excellent. The thickness of the heat-resistant resin layer (A) is preferably 15 μm or less, more preferably 12 μm or less, even more preferably 10 μm or less, still more preferably 8 μm or less, and even more preferably 7 μm or less from the viewpoint of flex resistance. There is no particular lower limit, but from the viewpoint of film formability, it is preferably 0.1 μm or more, more preferably 1 μm or more.

[0024] The haze value of the heat-resistant resin layer (A) is preferably 10.0% or less, more preferably 5.0% or less, even more preferably 1.0% or less, and particularly preferably 0.5% or less. The haze value of the heat-resistant resin layer (A) after heating at 150° C. for 1 hour is preferably 10.0% or less, more preferably 5.0% or less, even more preferably 1.0% or less, and particularly preferably 0.5% or less. When the haze value of the heat-resistant resin layer (A) is within this range, for example, it becomes easier to maintain low light diffusion in the laminate after forming the functional layer and peeling off the process film, and it becomes possible to improve optical properties such as total light transmittance. The lower limit of the haze value is not particularly limited and may be 0%. The haze value is measured by the method described in the examples below.

[0025] The heat-resistant resin layer (A) is preferably a layer made of a cured product of a curable resin composition (C1) containing a polymer component (M) that is a polyimide resin and a curable monomer (P). The heat-resistant resin layer (A) may be a single layer or may be made of multiple layers. From the viewpoint of thinning, a single layer is preferred. The method for forming the heat-resistant resin layer (A) will be described in detail in the method for producing the laminate described below.

[0026] (Polymer component (M)) The polyimide resin of the polymer component (M) has a high glass transition temperature (Tg) and excellent heat resistance. In addition, the polyimide resin is preferably an amorphous thermoplastic resin, since it can be used to form a coating film by a solution casting method and can easily produce a heat-resistant resin layer (A) with excellent optical isotropy. Furthermore, polyimide resins exhibit heat resistance and are soluble in general-purpose organic solvents, such as benzene and methyl ethyl ketone, which are low-boiling organic solvents. Here, the term "amorphous thermoplastic resin" refers to a thermoplastic resin whose melting point is not observed in differential scanning calorimetry.

[0027] The glass transition temperature of the polymer component (M) is preferably 250° C. or higher, more preferably 290° C. or higher, and even more preferably 320° C. or higher. By using a polymer component (M) having a Tg of 250° C. or higher, sufficient heat resistance can be imparted to the heat-resistant resin layer (A). For example, when a functional layer or the like is formed from a coating film, the heat-resistant resin layer (A) is prevented from being affected by heating (including solvent drying) during coating of the coating film, causing deformation or the like. As a result, the inherent functions of the functional layer of the laminate can be fully exhibited. The coating film is a film obtained by applying a coating material to a substrate or an object and, if necessary, subjecting it to treatments such as curing by drying, heating, etc. When the functional layer is a coating film, the coating film is obtained by applying a coating material containing components that form the functional layer to the heat-resistant resin layer (A) and subjecting it to curing treatments such as drying and heating or irradiation with active energy rays, or both. Here, Tg refers to the temperature at the maximum point of tan δ (loss modulus / storage modulus) obtained by viscoelasticity measurement (measurement in tension mode in the range of 0 to 400°C at a frequency of 10 Hz and a heating rate of 3°C / min).

[0028] The weight-average molecular weight (Mw) of the polyimide resin in the polymer component (M) is preferably 50,000 or more, more preferably 100,000 or more and 280,000 or less, and even more preferably 150,000 or more and 240,000 or less. If the weight-average molecular weight (Mw) is within this range, for example, when a functional layer or the like is formed from a coating film, thermal shrinkage of the heat-resistant resin layer (A) before and after heating (including solvent drying) during coating of the coating film is suppressed, and as a result, the inherent functions of the functional layer of the laminate can be fully exhibited. The molecular weight distribution (Mw / Mn) is preferably in the range of 1.0 to 5.0, more preferably 1.2 to 3.0. The weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn) are values ​​measured by gel permeation chromatography (GPC) and converted into polystyrene equivalent values.

[0029] The polyimide resin is not particularly limited as long as it does not impair the effects of the present invention, and examples thereof include aromatic polyimide resins, aromatic (carboxylic acid component)-aliphatic cycloimide (diamine component) polyimide resins, aliphatic cycloimide (carboxylic acid component)-aliphatic cycloimide (diamine component) polyimide resins, aliphatic cycloimide resins, and fluorinated aromatic polyimide resins. Among these, polyimide resins having an aromatic ring structure are preferred in one embodiment. Furthermore, polyimide resins having a fluoro group in the molecule, as described below, are preferred in another embodiment. Specifically, a polyimide resin obtained by using an aromatic diamine compound and a tetracarboxylic dianhydride, polymerizing the polyamic acid, and then chemically imidizing the polyamic acid is preferred.

[0030] Any aromatic diamine compound can be used as long as it is soluble in a common solvent (e.g., N,N-dimethylacetamide (DMAC)) and gives a polyimide having a predetermined transparency upon reaction with the tetracarboxylic dianhydride used in combination. Specifically, m-phenylenediamine, p-phenylenediamine, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl sulfide, 3,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfone, 3,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminobenzophenone, 3,3'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, 2,2-bis(4-aminophenyl)propane, 2,2-bis(3-aminophenyl)propane, 2-(3-aminophenyl)propane, 2,2-bis(4-aminophenyl)-2-(4-aminophenyl)propane, 2,2-bis(4-aminophenyl)-1,1,1,3,3,3-hexafluoropropane, 2,2-bis(3-aminophenyl)-1,1,1,3,3,3-hexafluoropropane, 2-(3-aminophenyl)-2-(4-aminophenyl)-1,1,1,3,3,3-hexafluoropropane, 1,3-bis(3-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(3-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 4,4'-bis(4-aminophenoxy)biphenyl, 3,3'-bis(4-aminophenoxy)biphenyl, 3,4'-bis(3-aminophenoxy)biphenyl, bis[4-(4-aminophenoxy)phenyl]sulfide, bis[3-(4-aminophenoxy)phenyl]sulfide, bis[4-(3-aminophenoxy)phenyl]sulfide, bis[3-(4-aminophenoxy)phenyl]sulfide, bis[3-(3-aminophenoxy)phenyl]sulfide, bis[3-(4-aminophenoxy)phenyl]sulfide, bis[3-(4-aminophenoxy)phenyl]sulfone, bis[4-(4-aminophenyl)]sulfone, bis[3-(3-aminophenoxy)phenyl]sulfone, bis[ 4-(3-aminophenyl) sulfone, bis[4-(3-aminophenoxy)phenyl] ether, bis[4-(4-aminophenoxy)phenyl] ether, bis[3-(3-aminophenoxy)phenyl] ether, bis[4-(3-aminophenoxy)phenyl] methane, bis[4-(4-aminophenoxy)phenyl] methane, bis[3-(3-aminophenoxy)phenyl] methane, bis[3-(4-aminophenoxy)phenyl] methane, 2,2-bis[4-(3-aminophenoxy)phenyl] propane, 2,2-bis[4 -(4-aminophenoxy)phenyl]propane, 2,2-bis[3-(3-aminophenoxy)phenyl]propane, 2,2-bis[4-(3-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, 2,2-bis[4-(4-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, 2,2-bis[3-(3-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, 2,2-bis[3-(4-aminophenoxy)phenyl]-1,1,1,3, Examples of such benzene derivatives include 3,3-hexafluoropropane, 1,3-bis[4-(4-amino-6-trifluoromethylphenoxy)-α,α-dimethylbenzyl]benzene, 1,3-bis[4-(4-amino-6-fluoromethylphenoxy)-α,α-dimethylbenzyl]benzene, 2,2'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dimethyl-4,4'-diaminobiphenyl, 3,3'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, and 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl.

[0031] These aromatic diamine compounds may be used alone or in combination of two or more kinds thereof. From the viewpoint of transparency and heat resistance, preferred aromatic diamine compounds include 2,2-bis(4-aminophenyl)-1,1,1,3,3,3-hexafluoropropane, 2,2-bis(3-aminophenyl)-1,1,1,3,3,3-hexafluoropropane, 2-(3-aminophenyl)-2-(4-aminophenyl)-1,1,1,3,3,3-hexafluoropropane, 2,2-bis[4-(3-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, 2,2-bis[4-(4-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, and 2,2-bis[3-(3-aminophenoxy)phenyl]-1,1,1,3,3 Examples of aromatic diamine compounds having a fluoro group include 1,3-hexafluoropropane, 2,2-bis[3-(4-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, 1,3-bis[4-(4-amino-6-trifluoromethylphenoxy)-α,α-dimethylbenzyl]benzene, 3,3'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, and 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl. It is preferred that at least one of the aromatic diamine compounds used be an aromatic diamine compound having a fluoro group, with 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl being particularly preferred. Using an aromatic diamine compound having a fluoro group makes it easier to achieve transparency, heat resistance, and solubility in solvents.

[0032] As with the aromatic diamine compounds, any tetracarboxylic acid dianhydride can be used as long as it is soluble in common solvents (e.g., N,N-dimethylacetamide (DMAC)) and provides a polyimide having a predetermined transparency. Specific examples include 4,4'-(1,1,1,3,3,3-hexafluoropropane-2,2-diyl)diphthalic dianhydride, pyromellitic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 1,4-hydroquinonedibenzoate-3,3',4,4'-tetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, and 3,3',4,4'-diphenylethertetracarboxylic dianhydride. These tetracarboxylic acid dianhydrides may be used alone, or two or more types of tetracarboxylic acid dianhydrides may be used together. From the viewpoints of transparency, heat resistance, and solubility in solvents, it is preferable to use a tetracarboxylic acid dianhydride having at least one type of fluoro group, such as 4,4'-(1,1,1,3,3,3-hexafluoropropane-2,2-diyl)diphthalic dianhydride.

[0033] The polymerization to form polyamic acid can be carried out by reacting the aromatic diamine compound and tetracarboxylic dianhydride while dissolving the resulting polyamic acid in a solvent that the polyamic acid is soluble in. Examples of the solvent that can be used for the polymerization to form polyamic acid include N,N-dimethylacetamide, N,N-dimethylformamide, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, and dimethyl sulfoxide.

[0034] The polymerization reaction to form polyamic acid is preferably carried out in a reaction vessel equipped with a stirrer while stirring. Examples include a method of dissolving a predetermined amount of aromatic diamine compound in the solvent, adding tetracarboxylic dianhydride while stirring, and carrying out a reaction to obtain polyamic acid, a method of dissolving tetracarboxylic dianhydride in a solvent, adding aromatic diamine compound while stirring, and carrying out a reaction to obtain polyamic acid, and a method of alternately adding aromatic diamine compound and tetracarboxylic dianhydride and carrying out a reaction to obtain polyamic acid.

[0035] There are no particular restrictions on the temperature of the polymerization reaction to form polyamic acid, but it is preferably carried out at a temperature of 0 to 70° C., more preferably 10 to 60° C., and even more preferably 20 to 50° C. By carrying out the polymerization reaction within the above range, it is possible to obtain a high-molecular-weight polyamic acid that is less colored and has excellent transparency.

[0036] The aromatic diamine compound and tetracarboxylic dianhydride used in the polymerization to form polyamic acid are generally used in approximately equimolar amounts, but the molar ratio of tetracarboxylic dianhydride to aromatic diamine compound (molar ratio) can be varied within a range of 0.95 to 1.05 to control the degree of polymerization of the resulting polyamic acid. The molar ratio of tetracarboxylic dianhydride to aromatic diamine compound is preferably within a range of 1.001 to 1.02, more preferably 1.001 to 1.01. By using a slight excess of tetracarboxylic dianhydride relative to the aromatic diamine compound, the degree of polymerization of the resulting polyamic acid can be stabilized and units derived from the tetracarboxylic dianhydride can be positioned at the polymer terminals, resulting in a polyimide with little coloration and excellent transparency.

[0037] The concentration of the resulting polyamic acid solution is preferably adjusted to an appropriate concentration (for example, about 10 to 30% by mass) so that the viscosity of the solution is kept appropriate and handling in the subsequent steps is easy.

[0038] An imidizing agent is added to the resulting polyamic acid solution to carry out a chemical imidization reaction. Examples of imidizing agents that can be used include carboxylic acid anhydrides such as acetic anhydride, propionic anhydride, succinic anhydride, phthalic anhydride, and benzoic anhydride. Acetic anhydride is preferred from the standpoints of cost and ease of removal after the reaction. The equivalent weight of the imidizing agent used is equal to or greater than the equivalent weight of the amide bond in the polyamic acid to be subjected to the chemical imidization reaction, and is preferably 1.1 to 5 times, and more preferably 1.5 to 4 times, the equivalent weight of the amide bond. Using a slight excess of the imidizing agent relative to the amide bond in this way allows the imidization reaction to be carried out efficiently even at relatively low temperatures.

[0039] In the chemical imidization reaction, an aliphatic, aromatic, or heterocyclic tertiary amine such as pyridine, picoline, quinoline, isoquinoline, trimethylamine, triethylamine, etc. can be used as an imidization accelerator. By using such amines, the imidization reaction can be carried out efficiently at a low temperature, and as a result, coloration during the imidization reaction can be suppressed, making it easier to obtain a more transparent polyimide.

[0040] There are no particular restrictions on the temperature for the chemical imidization reaction, but it is preferably carried out at a temperature of 10° C. or higher but lower than 50° C., and more preferably at a temperature of 15° C. or higher but lower than 45° C. By carrying out the chemical imidization reaction at a temperature of 10° C. or higher but lower than 50° C., coloration during the imidization reaction is suppressed, and a polyimide with excellent transparency can be obtained.

[0041] Thereafter, if necessary, a poor solvent for polyimide is added to the polyimide solution obtained by the chemical imidization reaction to precipitate the polyimide into powder, followed by drying.

[0042] The polyimide resin is preferably soluble in a low-boiling organic solvent such as benzene or methyl ethyl ketone. In particular, it is preferably soluble in methyl ethyl ketone. When the polyimide resin is soluble in methyl ethyl ketone, the heat-resistant resin layer (A) described below, which is made of a cured product of the curable resin composition (C1), can be easily formed by coating and drying.

[0043] A polyimide resin containing a fluoro group is particularly preferred from the viewpoint that it is easily dissolved in a general-purpose organic solvent having a low boiling point, such as methyl ethyl ketone, and a coating layer can be easily formed by a coating method. The polyimide resin having a fluoro group is preferably an aromatic polyimide resin having a fluoro group in the molecule, and preferably has a skeleton represented by the following chemical formula in the molecule. [ka]

[0044] The polyimide resin having the skeleton represented by the above chemical formula has an extremely high Tg exceeding 300°C due to the high rigidity of the skeleton. This significantly improves the heat resistance of the heat-resistant resin layer (A). Furthermore, the linear skeleton provides relatively high flexibility, facilitating the high elongation at break of the heat-resistant resin layer (A). Furthermore, the polyimide resin having the above skeleton is soluble in low-boiling, general-purpose organic solvents such as methyl ethyl ketone due to the presence of fluoro groups. Therefore, the heat-resistant resin layer (A) can be formed as a coating film by solution casting, and the solvent can be easily removed by drying. The polyimide resin having the skeleton represented by the above chemical formula can be obtained by polymerization and imidization of the polyamic acid described above using 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl and 4,4'-(1,1,1,3,3,3-hexafluoropropane-2,2-diyl)diphthalic dianhydride.

[0045] The polymer component (M) may further contain other components, such as polyarylate resins. Polyarylate resin is a resin made of a polymer compound obtained by reacting an aromatic diol with an aromatic dicarboxylic acid or its chloride. Like polyimide resin, polyarylate resin has a relatively high Tg and relatively good elongation properties. There are no particular limitations on the polyarylate resin, and known polyarylate resins can be used.

[0046] Examples of aromatic diols include bis(hydroxyphenyl)alkanes such as bis(4-hydroxyphenyl)methane (bisphenol F), bis(3-methyl-4-hydroxyphenyl)methane, 1,1-bis(4'-hydroxyphenyl)ethane, 1,1-bis(3'-methyl-4'-hydroxyphenyl)ethane, 2,2-bis(4'-hydroxyphenyl)propane (bisphenol A), 2,2-bis(3'-methyl-4'-hydroxyphenyl)propane, 2,2-bis(4'-hydroxyphenyl)butane, and 2,2-bis(4'-hydroxyphenyl)octane; and bis(hydroxyphenyl)cycloalkanes such as 1,1-bis(4'-hydroxyphenyl)cyclopentane, 1,1-bis(4'-hydroxyphenyl)cyclohexane (bisphenol Z), and 1,1-bis(4'-hydroxyphenyl)-3,3,5-trimethylcyclohexane.Bis(4-hydroxyphenyl)phenylmethane, bis(3-methyl-4-hydroxyphenyl)phenylmethane, bis(2,6-dimethyl-4-hydroxyphenyl)phenylmethane, bis(2,3,6-trimethyl-4-hydroxyphenyl)phenylmethane, bis(3-t-butyl-4-hydroxyphenyl)phenylmethane, bis(3-phenyl-4-hydroxyphenyl)phenylmethane, bis(3-fluoro-4-hydroxyphenyl)phenylmethane, bis(3-bromo-4-hydroxyphenyl)phenyl Methane, bis(4-hydroxyphenyl)-4-fluorophenylmethane, bis(3-fluoro-4-hydroxyphenyl)-4-fluorophenylmethane, bis(4-hydroxyphenyl)-4-chlorophenylmethane, bis(4-hydroxyphenyl)-4-bromophenylmethane, bis(3,5-dimethyl-4-hydroxyphenyl)-4-fluorophenylmethane, 1,1-bis(4'-hydroxyphenyl)-1-phenylethane [bisphenol P], 1,1-bis(3'-methyl-4'-hydroxyphenyl) )-1-phenylethane, 1,1-bis(3'-t-butyl-4'-hydroxyphenyl)-1-phenylethane, 1,1-bis(3'-phenyl-4'-hydroxyphenyl)-1-phenylethane, 1,1-bis(4'-hydroxyphenyl)-1-(4'-nitrophenyl)ethane, 1,1-bis(3'-bromo-4'-hydroxyphenyl)-1-phenylethane, 1,1-bis(4'-hydroxyphenyl)-1-phenylpropane, bis(4-hydroxyphenyl)diphenylmethane, bis(4-hydroxyphenyl)diphenylmethane bis(hydroxyphenyl)phenylalkanes such as bis(4-hydroxyphenyl)dibenzylmethane; bis(hydroxyphenyl)ethers such as bis(4-hydroxyphenyl)ether and bis(3-methyl-4-hydroxyphenyl)ether; bis(hydroxyphenyl)ketones such as bis(4-hydroxyphenyl)ketone and bis(3-methyl-4-hydroxyphenyl)ketone; bis(hydroxyphenyl)sulfides such as bis(4-hydroxyphenyl)sulfide and bis(3-methyl-4-hydroxyphenyl)sulfide;Examples of suitable bis(hydroxyphenyl)sulfoxides include bis(4-hydroxyphenyl)sulfoxide and bis(3-methyl-4-hydroxyphenyl)sulfoxide; bis(hydroxyphenyl)sulfones such as bis(4-hydroxyphenyl)sulfone [bisphenol S] and bis(3-methyl-4-hydroxyphenyl)sulfone; and bis(hydroxyphenyl)fluorenes such as 9,9-bis(4'-hydroxyphenyl)fluorene and 9,9-bis(3'-methyl-4'-hydroxyphenyl)fluorene.

[0047] Examples of aromatic dicarboxylic acids or chlorides thereof include phthalic acid, isophthalic acid, terephthalic acid, 4,4'-biphenyldicarboxylic acid, diphenoxyethanedicarboxylic acid, diphenyl ether 4,4'-dicarboxylic acid, 4,4'-diphenylsulfonedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, and chlorides thereof. The polyarylate resin used may be a modified polyarylate resin. Among these, a resin made of a polymer compound obtained by reacting 2,2-bis(4'-hydroxyphenyl)propane with isophthalic acid is preferred.

[0048] The polymer component (M) can be used alone or in combination of two or more. The polymer component (M) may also be used in combination with a polymer component (M') having a glass transition temperature of less than 250°C. Examples of the polymer component (M') include polyamide resins and polyarylate resins having a Tg of less than 250°C, with polyamide resins being preferred.

[0049] The polyamide resin is preferably one that is soluble in an organic solvent, and is preferably a rubber-modified polyamide resin, such as that described in JP-A-2004-035638.

[0050] As the polymer component (M) and the polymer component (M'), those using a single type of polyimide resin, those using multiple different types of polyimide resins, and those in which at least one of a polyamide resin and a polyarylate resin is added to a polyimide resin are preferred from the viewpoint of being able to adjust the elongation properties and from the viewpoint of solvent resistance.

[0051] When a polyamide resin or a polyarylate resin having a Tg of less than 250°C is added to a polyimide resin, the amount of the resin added is, from the viewpoint of imparting appropriate flexibility while maintaining a high Tg, preferably 100 parts by mass or less, more preferably 70 parts by mass or less, even more preferably 50 parts by mass or less, and even more preferably 30 parts by mass or less, relative to 100 parts by mass of the polyimide resin, and is preferably 1 part by mass or more, more preferably 3 parts by mass or more.

[0052] (Curable monomer (P)) The curable monomer (P) is a monomer having a polymerizable unsaturated bond and capable of participating in a polymerization reaction, or a polymerization reaction and a crosslinking reaction. In this specification, the term "curing" refers to a broad concept including the "polymerization reaction of a monomer" or the "polymerization reaction of a monomer and the subsequent crosslinking reaction of the polymer."

[0053] The molecular weight of the curable monomer (P) is usually 3,000 or less, preferably 150 to 2,000, and more preferably 150 to 1,000. The number of polymerizable unsaturated bonds in the curable monomer (P) is not particularly limited. The curable monomer (P) may be a monofunctional monomer having one polymerizable unsaturated bond, or a polyfunctional monomer such as a di- to hexa-functional monomer having multiple polymerizable unsaturated bonds.

[0054] The monofunctional monomer includes a monofunctional (meth)acrylic acid derivative. The monofunctional (meth)acrylic acid derivative is not particularly limited, and known compounds can be used, such as monofunctional (meth)acrylic acid derivatives having a nitrogen atom, monofunctional (meth)acrylic acid derivatives having an alicyclic structure, and monofunctional (meth)acrylic acid derivatives having a polyether structure.

[0055] The polyfunctional monomer includes polyfunctional (meth)acrylic acid derivatives. The polyfunctional (meth)acrylic acid derivative is not particularly limited, and known compounds can be used, for example, di- to hexa-functional (meth)acrylic acid derivatives. Specific examples of bifunctional (meth)acrylic acid derivatives include tricyclodecane dimethanol di(meth)acrylate, polyethylene glycol di(meth)acrylate, propoxylated ethoxylated bisphenol A di(meth)acrylate, ethoxylated bisphenol A di(meth)acrylate, 1,10-decanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 9,9-bis[4-(2-acryloyloxyethoxy)phenyl]fluorene, urethane acrylate, etc. Among these, from the viewpoint of heat resistance and toughness, tricyclodecane dimethanol di(meth)acrylate and the like, which have R 7 and propoxylated ethoxylated bisphenol A di(meth)acrylate, ethoxylated bisphenol A di(meth)acrylate, etc., in which R 7 and 9,9-bis[4-(2-acryloyloxyethoxy)phenyl]fluorene, etc., in which R 7 Preferably, the divalent organic group represented by the following formula has a 9,9-bisphenylfluorene skeleton. From the viewpoint of imparting flexibility, urethane acrylate is preferred.

[0056] Other examples of bifunctional (meth)acrylic acid derivatives include neopentyl glycol adipate di(meth)acrylate, hydroxypivalic acid neopentyl glycol di(meth)acrylate, caprolactone-modified dicyclopentenyl di(meth)acrylate, ethylene oxide-modified phosphate di(meth)acrylate, di(acryloxyethyl) isocyanurate, and allylated cyclohexyl di(meth)acrylate.

[0057] Examples of trifunctional (meth)acrylic acid derivatives include trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, propionic acid-modified dipentaerythritol tri(meth)acrylate, propylene oxide-modified trimethylolpropane tri(meth)acrylate, and tris(acryloxyethyl)isocyanurate. Examples of tetrafunctional (meth)acrylic acid derivatives include pentaerythritol tetra(meth)acrylate. Examples of the pentafunctional (meth)acrylic acid derivatives include propionic acid-modified dipentaerythritol penta(meth)acrylate. Examples of the hexafunctional (meth)acrylic acid derivative include dipentaerythritol hexa(meth)acrylate and caprolactone-modified dipentaerythritol hexa(meth)acrylate.

[0058] A cyclopolymerizable monomer may be used as the curable monomer (P). The cyclopolymerizable monomer is a monomer that has the property of undergoing radical polymerization while undergoing cyclization.

[0059] The curable monomer (P) can be used alone or in combination of two or more. Among these, the curable monomer (P) is preferably a polyfunctional monomer, since it can provide a heat-resistant resin layer (A) having excellent heat resistance and solvent resistance. As the polyfunctional monomer, a bifunctional (meth)acrylic acid derivative is preferred, from the viewpoints that it is easily mixed with the polymer component (M), and the polymer is less likely to undergo cure shrinkage, thereby suppressing curling of the cured product.

[0060] <Curable resin composition (C1)> The curable resin composition (C1) used in the present invention can be prepared by mixing the polymer component (M), the curable monomer (P), and, if desired, a polymerization initiator described below and other components, and dissolving or dispersing the mixture in a suitable solvent.

[0061] The total content of the polymer component (M) and the curable monomer (P) in the curable resin composition (C1) is preferably 40 to 99.5 mass%, more preferably 60 to 99 mass%, and even more preferably 80 to 98 mass%, based on the total mass of the curable resin composition (C1) excluding the solvent.

[0062] The content of the polymer component (M) and the curable monomer (P) in the curable resin composition (C1), in terms of the mass ratio of the polymer component (M) to the curable monomer (P), is preferably polymer component (M):curable monomer (P)=20:80 to 90:10, more preferably 30:70 to 70:30, and even more preferably 40:60 to 60:40. In the curable resin composition (C1), when the mass ratio of the polymer component (M): the curable monomer (P) is within this range, the heat shrinkage rate of the heat-resistant resin layer (A) before and after heat treatment at high temperature tends to decrease, and the breaking elongation tends to be maintained. The content of the polyimide resin in the polymer component (M) is preferably 70 to 100 mass %, more preferably 80 to 100 mass %, and even more preferably 95 to 100 mass %, based on the total mass of the polymer component (M) excluding the solvent.

[0063] When a combination of multiple resins with different solvent solubilities is used as the polymer component (M), such as a combination of the above-mentioned polyimide resin with a polyamide resin or a polyarylate resin, it is preferable to first dissolve the resins in solvents suitable for each resin, and then add a solution of the other resin to the low-boiling organic solvent in which the resin has been dissolved.

[0064] The curable resin composition (C1) may contain a polymerization initiator if desired. The polymerization initiator may be any initiator that initiates a curing reaction, and examples thereof include a thermal polymerization initiator and a photopolymerization initiator.

[0065] Examples of the thermal polymerization initiator include organic peroxides and azo compounds. Examples of organic peroxides include dialkyl peroxides such as di-t-butyl peroxide, t-butylcumyl peroxide, and dicumyl peroxide; diacyl peroxides such as acetyl peroxide, lauroyl peroxide, and benzoyl peroxide; ketone peroxides such as methyl ethyl ketone peroxide, cyclohexanone peroxide, 3,3,5-trimethylcyclohexanone peroxide, and methylcyclohexanone peroxide; and peroxides such as 1,1-bis(t-butylperoxy)cyclohexane. Examples of the peroxyester include ketals; hydroperoxides such as t-butyl hydroperoxide, cumene hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, p-menthane hydroperoxide, diisopropylbenzene hydroperoxide, and 2,5-dimethylhexane-2,5-dihydroperoxide; and peroxyesters such as t-butyl peroxyacetate, t-butyl peroxy-2-ethylhexanoate, t-butyl peroxybenzoate, and t-butyl peroxyisopropyl carbonate. Examples of azo compounds include 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis(2-cyclopropylpropionitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), 1,1'-azobis(cyclohexane-1-carbonitrile), 2-(carbamoylazo)isobutyronitrile, and 2-phenylazo-4-methoxy-2,4-dimethylvaleronitrile.

[0066] Photopolymerization initiators include 2,2-dimethoxy-1,2-diphenylethan-1-one, 1-hydroxy-cyclohexyl-phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1-[4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]phenyl]-2-methyl-propan-1-one, 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one, 2-benzyl-2-dimethylamine, and the like. Alkylphenone-based photopolymerization initiators such as 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, ethyl (2,4,6-trimethylbenzoyl)-phenylphosphine phosphate, and bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide; bis(η 5Titanocene photopolymerization initiators such as (2,4-cyclopentadien-1-yl)-bis[2,6-difluoro-3-(1H-pyrrol-1-yl)-phenyl]titanium; oxime ester photopolymerization initiators such as 1,2-octanedione-1-[4-(phenylthio)-2-(O-benzoyloxime)] and ethanone-1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-1-(O-acetyloxime); benzophenone, p-chlorobenzophenone, benzoylbenzoic acid, methyl o-benzoylbenzoate, 4-methylbenzophenone, 4-phenylbenzophenone, hydroxybenzophenone, acrylated benzophenone, 4-benzoyl benzophenone-based photopolymerization initiators such as 13-acryloyl-4'-methyl-diphenyl sulfide, 3,3'-dimethyl-4-methoxybenzophenone, 2,4,6-trimethylbenzophenone, and 4-(13-acryloyl-1,4,7,10,13-pentaoxatridecyl)-benzophenone; and thioxanthone-based photopolymerization initiators such as thioxanthone, 2-chlorothioxanthone, 3-methylthioxanthone, 2,4-dimethylthioxanthone, 2,4-diisopropylthioxanthone, 2,4-dichlorothioxanthone, 1-chloro-4-propoxythioxanthone, 2-methylthioxanthone, 2-isopropylthioxanthone, and 4-isopropylthioxanthone. The polymerization initiators can be used alone or in combination of two or more.

[0067] The content of the polymerization initiator is preferably from 0.05 to 15 mass %, more preferably from 0.05 to 10 mass %, and even more preferably from 0.05 to 5 mass %, based on the total mass of the curable resin composition (C1).

[0068] The curable resin composition (C1) may contain, in addition to the polymer component (M), the curable monomer (P), and the polymerization initiator, a photopolymerization initiation aid such as triisopropanolamine or 4,4'-diethylaminobenzophenone.

[0069] The solvent used in preparing the curable resin composition (C1) is not particularly limited, and examples thereof include aliphatic hydrocarbon solvents such as n-hexane and n-heptane; aromatic hydrocarbon solvents such as toluene and xylene; halogenated hydrocarbon solvents such as dichloromethane, ethylene chloride, chloroform, carbon tetrachloride, 1,2-dichloroethane, and monochlorobenzene; alcohol solvents such as methanol, ethanol, propanol, butanol, and propylene glycol monomethyl ether; ketone solvents such as acetone, methyl ethyl ketone, 2-pentanone, isophorone, and cyclohexanone; ester solvents such as ethyl acetate and butyl acetate; cellosolve solvents such as ethyl cellosolve; and ether solvents such as 1,3-dioxolane.

[0070] The content of the solvent in the curable resin composition (C1) is not particularly limited, but is usually 0.1 to 1,000 parts by mass, preferably 1 to 100 parts by mass, per part by mass of the polymer component (M). By appropriately adjusting the amount of the solvent, the viscosity of the curable resin composition (C1) can be adjusted appropriately.

[0071] The curable resin composition (C1) may further contain known additives such as a plasticizer, an antioxidant, and an ultraviolet absorber, within the range that does not impair the object and effect of the present invention.

[0072] <Properties of the heat-resistant resin layer (A)> The heat-resistant resin layer (A) used in the present invention exhibits heat shrinkability (shrinks upon heating). The heat shrinkage rate when heat-treated at 100°C for 2 minutes is preferably 0.08% or less, more preferably 0.05% or less, and even more preferably 0.01% or less. When the heat shrinkage rate of the heat-resistant resin layer (A) is within this range, the heat resistance of the heat-resistant resin layer (A) is high. Therefore, when a manufacturing process involving heating is performed after the formation of the heat-resistant resin layer (A), for example, when a functional layer is formed on the heat-resistant resin layer (A) by coating and heat drying as described above, heat shrinkage is suppressed, and mechanical deformation (e.g., warping, peeling, wrinkling, etc.) of the functional layer is less likely to occur, allowing the functional layer to fully exhibit its intended functions. The heat shrinkage can be measured and evaluated, for example, by the following method. A 40 μm thick heat-resistant resin layer (A) was cut into a 5 mm × 30 mm test piece, and a thermomechanical analyzer (NETZSCH Japan, model "TMA4000SE") was used to hold the heat-resistant resin layer (A) with the chuck distance set to 20 mm. The heat-resistant resin layer was then heated from 25 ° C. to 100 ° C. at a heating rate of 5 ° C. / min, held for 2 minutes, and then cooled to 25 ° C. at a cooling rate of 5 ° C. / min. The rate of change in displacement in the longitudinal direction (the percentage of the amount of displacement relative to the 20 mm chuck distance) was taken as the thermal change rate. A negative value indicates that the heat-resistant resin layer (A) has shrunk (thermal shrinkage), and a positive value indicates that the heat-resistant resin layer (A) has expanded.

[0073] The breaking elongation of the heat-resistant resin layer (A) is preferably 2.5% or more, more preferably 3.0% or more, and even more preferably 3.5% or more. When the breaking elongation of the heat-resistant resin layer (A) is within this range, for example, 2.5% or more, it becomes easy to adjust the breaking elongation of the laminate including the functional layer to about 2% or more, and as a result, it becomes easy to obtain a laminate with excellent flexibility. The breaking elongation can be measured and evaluated, for example, by the following method. The 5 μm thick heat-resistant resin layer (A) was cut into a 15 mm × 150 mm test piece, and the breaking elongation was measured according to JIS K7127:1999. Specifically, the test piece was subjected to a tensile test at a speed of 200 mm / min using a tensile tester (Shimadzu Corporation, Autograph) with the chuck distance set to 100 mm, and the breaking elongation (%) was measured. Note that if the test piece did not have a yield point, the tensile breaking strain was taken as the breaking elongation, and if it did have a yield point, the strain at the yield point was taken as the breaking elongation.

[0074] The in-plane retardation of the heat-resistant resin layer (A) is preferably 2.0 nm or less, more preferably 1.5 nm or less, even more preferably 1.0 nm or less, still more preferably 0.5 nm or less, and particularly preferably 0.3 nm or less. The in-plane retardation is calculated by the following formula (1). Re(λ)=(nx-ny)×d (1) Here, Re(λ) is the in-plane retardation of the heat-resistant resin layer (A) measured with light of wavelength λ nm at 23° C. For example, “Re(450)” is the in-plane retardation of the heat-resistant resin layer (A) measured with light of wavelength 450 nm at 23° C. Furthermore, “nx” is the refractive index in the direction in which the in-plane refractive index is maximum (i.e., the slow axis direction), “ny” is the refractive index in the in-plane direction perpendicular to the slow axis (i.e., the fast axis direction), and d is the thickness (nm) of the heat-resistant resin layer (A). On the other hand, the retardation in the thickness direction is usually −500 nm or less, preferably −450 nm or less. The value obtained by dividing the in-plane retardation by the thickness of the heat-resistant resin layer (A) (birefringence) is usually 100×10 -5 or less, preferably 20 × 10 -5 The following is the result. When the in-plane retardation, thickness direction retardation and birefringence of the heat-resistant resin layer (A) are within the above ranges, the layer has excellent optical isotropy and can be preferably used as a member for optical applications.

[0075] When the heat-resistant resin layer (A) used in the present invention is a layer made of a cured product of a curable resin composition (C1) containing a polymer component (M) that is a polyimide resin and a curable monomer (P), the heat-resistant resin layer (A) has excellent solvent resistance. Because of its excellent solvent resistance, the surface of the heat-resistant resin layer (A) is hardly dissolved, even when an organic solvent is used to form another layer on the surface of the heat-resistant resin layer (A). Therefore, even when a functional layer is formed on the surface of the heat-resistant resin layer (A) using a resin solution containing an organic solvent, the components of the heat-resistant resin layer (A) are unlikely to penetrate into the functional layer, and the inherent functions of the functional layer are unlikely to be impaired. From the above viewpoints, the gel fraction of the heat-resistant resin layer (A) is preferably 80% or more, more preferably 85% or more, even more preferably 87% or more, and particularly preferably 90% or more. A heat-resistant resin layer (A) having a gel fraction of 80% or more has excellent solvent resistance, so that even when an organic solvent is used to form a functional layer on the surface of the heat-resistant resin layer (A) by coating, the surface of the heat-resistant resin layer (A) hardly dissolves, making it easy to obtain a laminate having excellent solvent resistance. Here, the gel fraction is calculated, for example, by performing the following operations (a), (b), and (c) and dividing the measured weight of the structure after drying by the weight of the structure before immersion in MEK (methyl ethyl ketone) solvent. (a) The heat-resistant resin layer (A) was wrapped in a mesh (NBC Meshtec, α_UX SCREEN 150-035 / 380TW) and stapled together to form a structure, and the weight of the structure was measured. (b) The structure was immersed in a bottle filled with methyl ethyl ketone (MEK) solvent, sealed, and left at 25°C for 36 hours. (c) The structure was removed from the solvent and dried at 100°C for 60 minutes, and the weight of the structure after drying was measured.

[0076] <Processing film> The laminate of the present invention includes a casting film, which is used as a support for forming the heat-resistant resin layer (A). As described above, the dimensional change rate of the above-mentioned cast film in the MD when heated at 150° C. for 1 hour is 0.5% or less. Such a processing film can be a plastic film that has been annealed. The annealing treatment relieves the residual stress that occurs during the production of the plastic film. This reduces the dimensional change rate, particularly in the MD, when the processing film is heat-treated.

[0077] The annealing treatment of the cast film is preferably carried out in an oven or the like in an air atmosphere at 120 to 200°C for 0.3 to 3 hours, more preferably at 140 to 160°C for 0.4 to 1 hour. A commercially available annealed plastic film may also be used, such as the annealed PET film "2000AF2·PET50csOB" (manufactured by Aim Co., Ltd., thickness 50 μm).

[0078] The casting film has a surface facing the heat-resistant resin layer (A) (hereinafter referred to as the first surface) and a surface opposite thereto (hereinafter referred to as the second surface). As described above, it is preferable that the first surface of the heat-resistant resin layer (A) is peelable from the heat-resistant resin layer (A) and that the peel strength between the first surface and the heat-resistant resin layer (A) is 500 mN / 50 mm or less after heating at 150°C for 1 hour.

[0079] The casting film may have a release layer as described above, or may not have a release layer, but from the viewpoints of cost and ease of production, an embodiment without a release layer is preferred. When the casting film has a release layer, the surface of the release layer facing the heat-resistant resin layer (A) is the first surface.

[0080] The second surface of the casting film is preferably provided with an oligomer block layer, which can prevent contamination of the production line due to oligomer precipitation on the casting film surface under high temperature conditions and problems in optical inspection.

[0081] The process film is preferably in the form of a film, which is not limited to a long film but also includes a short, flat film. The process film is not particularly limited, but plastic films such as polyester films such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, etc., and polyolefin films such as polyethylene and polypropylene, etc. are preferred. For ease of handling, the casting film may have a release layer formed on the plastic film. The release layer can be formed by a known method using a conventionally known release agent such as a silicone-based release agent, a fluorine-based release agent, an alkyd-based release agent, or an olefin-based release agent. The thickness of the release layer is not particularly limited, but is usually 0.02 to 2.0 μm, more preferably 0.05 to 1.5 μm. From the viewpoint of ease of handling, the thickness of the casting film is preferably from 1 to 500 μm, more preferably from 5 to 300 μm, and particularly preferably from 20 to 150 μm. The processing film is usually peeled off in a predetermined process depending on the application of the laminate.

[0082] <Functional layer> The functional layer that can be provided on the heat-resistant resin layer (A) is not particularly limited, and examples thereof include a conductive layer, an adhesive layer, a pressure-sensitive adhesive layer, a tacky adhesive layer, a gas barrier layer, an impact absorbing layer, a hard coat layer, and an anti-reflection layer.

[0083] For example, materials constituting conductive layers (electrodes, transparent conductive layers, etc.) used as functional layers include metals, alloys, metal oxides, electrically conductive compounds, and mixtures thereof. Examples of transparent conductive layers include semiconductive metal oxides such as antimony-doped tin oxide (ATO), fluorine-doped tin oxide (FTO), tin oxide, germanium-doped zinc oxide (GZO), zinc oxide, indium oxide, indium tin oxide (ITO), and indium zinc oxide (IZO); metals such as gold, silver, chromium, and nickel; mixtures of these metals with conductive metal oxides; inorganic conductive substances such as copper iodide and copper sulfide; and organic conductive materials such as polyaniline, polythiophene, and polypyrrole. Metals such as silver may be aggregated in particulate form, such as nanofillers, nanorods, and nanofibers, to form transparent conductive layers. Examples of methods for forming the conductive layer include printing, vapor deposition, sputtering, ion plating, thermal CVD, plasma CVD, etc. Alternatively, for example, a transparent conductive layer may be obtained from a coating film by applying a coating material containing particulate metal to the laminate for transparent conductive film. The thickness of the conductive layer may be appropriately selected depending on the application, etc. It is usually 10 nm to 50 μm, and preferably 20 nm to 20 μm.

[0084] The adhesive layer is a layer used, for example, when attaching the laminate to an adherend, etc. The material for forming the adhesive layer is not particularly limited, and known adhesives or pressure-sensitive adhesives such as acrylic, silicone, rubber, and epoxy adhesives, heat seal materials, etc. can also be used, and an epoxy adhesive is preferred as the material for forming the adhesive layer. Similarly, the pressure-sensitive adhesive layer is a layer used, for example, when attaching the laminate to an adherend or the like. Examples of pressure-sensitive adhesives used in the pressure-sensitive adhesive layer include acrylic pressure-sensitive adhesives, urethane pressure-sensitive adhesives, silicone pressure-sensitive adhesives, rubber pressure-sensitive adhesives, etc. Among these, acrylic pressure-sensitive adhesives and urethane pressure-sensitive adhesives are preferred in terms of adhesive strength, transparency, and handleability. Furthermore, pressure-sensitive adhesives capable of forming a crosslinked structure are preferred. The pressure-sensitive adhesive may be in any form, such as a solvent-type pressure-sensitive adhesive, an emulsion-type pressure-sensitive adhesive, or a hot-melt pressure-sensitive adhesive.

[0085] The thickness of the laminate including the functional layer is usually determined by the thickness of the intended functional layer and the thickness of the laminate without the functional layer. The thickness is the sum of the thickness of the laminate.

[0086] [Method of manufacturing laminate] The method for producing a laminate of the present invention includes the following steps 1 and 2. Step 1: A step of forming a (coating film) on one side of a processing film using a curable resin composition (C1) containing a polymer component (M) and a curable monomer (P). Step 2: A step of curing the heat-resistant resin layer (A) (coating film) obtained in Step 1 to form the heat-resistant resin layer (A).

[0087] Furthermore, in the case of a laminate having a heat-resistant resin layer (B) like the above-mentioned laminate 41, the method for producing this laminate further includes the following steps 3 and 4 in addition to the above-mentioned steps 1 and 2. Step 3: A step of forming a heat-resistant resin layer (B) (coating film) on the other surface of the processed film using a curable resin composition (C2) containing a polymer component (N) and / or a curable monomer (Q). Step 4: A step of curing the heat-resistant resin layer (B) (coating film) obtained in Step 3 to form the heat-resistant resin layer (B).

[0088] Furthermore, in the case of a laminate having a functional layer, such as the laminates 21 and 31 described above, the method for producing this laminate further includes the following step 5 in addition to the above steps 1 and 2. Step 5: A step of forming a functional layer on the heat-resistant resin layer (A) of the laminate obtained in Step 2.

[0089] In step 1, the method for applying the curable resin composition (C1) onto the casting film is not particularly limited, and known application methods such as spin coating, spray coating, bar coating, knife coating, roll coating, blade coating, die coating, and gravure coating can be used.

[0090] The method for drying the resulting coating film is not particularly limited, and any conventionally known drying method such as hot air drying, hot roll drying, or infrared irradiation can be used. The temperature for drying the coating film is usually 30 to 150°C, preferably 50 to 130°C.

[0091] In step 2, the method for curing the heat-resistant resin layer (A) (coating film) is not particularly limited, and known methods can be used. For example, when the heat-resistant resin layer (A) (coating film) is formed using a curable resin composition (C1) containing a thermal polymerization initiator, the heat-resistant resin layer (A) (coating film) can be cured by heating the heat-resistant resin layer (A) (coating film). The heating temperature is usually 30 to 150°C, preferably 50 to 130°C. When the heat-resistant resin layer (A) (coating film) is formed using a curable resin composition (C1) containing a photopolymerization initiator, the heat-resistant resin layer (A) (coating film) can be cured by irradiating the heat-resistant resin layer (A) (coating film) with active energy rays. The active energy rays can be irradiated using a high-pressure mercury lamp, an electrodeless lamp, a xenon lamp, or the like.

[0092] The wavelength of the active energy ray is preferably 200 to 400 nm, more preferably 350 to 400 nm. The irradiance of the active energy ray is usually 50 to 1,000 mW / cm. 2 , preferably 70 to 300 mW / cm 2 The amount of active energy rays is in the range of 50 to 5,000 mJ / cm 2 , preferably 300 to 4,000 mJ / cm 2 The irradiation time is usually 0.1 to 1,000 seconds, preferably 1 to 500 seconds, and more preferably 10 to 100 seconds. In consideration of the heat load in the light irradiation step, irradiation may be carried out multiple times to satisfy the above-mentioned light amount.

[0093] In this case, in order to prevent deterioration of the polymer component (M) and coloring of the heat-resistant resin layer (A) due to irradiation with active energy rays, the curable resin composition (C1) may be irradiated with active energy rays through a filter that absorbs light of wavelengths unnecessary for the curing reaction. According to this method, light of wavelengths unnecessary for the curing reaction and that deteriorate the polymer component (M) is absorbed by the filter, so deterioration of the polymer component (M) is suppressed and a colorless and transparent heat-resistant resin layer (A) can be easily obtained. The filter may be a resin film such as a polyethylene terephthalate film. When a resin film is used, it is preferable to provide a step of laminating a resin film such as a polyethylene terephthalate film on the heat-resistant resin layer (A) (coating film) between steps 1 and 2. The resin film is usually peeled off after step 2.

[0094] The heat-resistant resin layer (A) (coating film) can also be cured by irradiating it with an electron beam. When irradiating with an electron beam, the heat-resistant resin layer (A) (coating film) can usually be cured without using a photopolymerization initiator. When irradiating with an electron beam, an electron beam accelerator or the like can be used. The irradiation dose is usually in the range of 10 to 1,000 krad. The irradiation time is usually 0.1 to 1,000 seconds, preferably 1 to 500 seconds, and more preferably 10 to 100 seconds.

[0095] The heat-resistant resin layer (A) (coating film) may be cured in an inert gas atmosphere such as nitrogen gas, if necessary. By performing the curing in an inert gas atmosphere, it becomes easier to avoid oxygen, moisture, etc. from interfering with the curing.

[0096] In step 3, the method of applying the curable resin composition (C2) to the second surface of the casting film and the method of drying the resulting heat-resistant resin layer (B) (coating film) can be performed in the same manner as in step 1 described above. In step 4, the heat-resistant resin layer (B) (coating film) can be cured by the same method as in step 2. In step 3, if only the polymerizable component (N) is applied to form a coating film, this step is unnecessary.

[0097] In step 5, as a method for forming a desired functional layer on the heat-resistant resin layer (A) obtained in step 2, the methods described above can be appropriately adopted depending on the functional layer to be used.

[0098] In this way, the manufacturing method including the above steps 1 and 2, the manufacturing method including the above steps 1 to 4, and the manufacturing method including the above steps 1, 2, and 5 utilize a casting film to form the heat-resistant resin layer (A), or the heat-resistant resin layer (A) and the functional layer.

[0099] According to the above-described method for producing a laminate, the laminate can be produced efficiently, continuously, and easily.

[0100] [Transparent conductive film] A transparent conductive film according to one embodiment of the present invention comprises the above laminate and a transparent conductive layer provided on the heat-resistant resin layer (A) of the above laminate. In other words, the transparent conductive film according to one embodiment of the present invention has a transparent conductive layer as the functional layer, and comprises a process film, a heat-resistant resin layer (A), and a transparent conductive layer in this order. When the transparent conductive film is actually used, the processing film is peeled off from the transparent conductive film and the film is incorporated into a display or a solar cell panel, or attached to the substrate of a touch sensor for a touch panel. For example, when the transparent conductive film has an adhesive layer as described below, the transparent conductive film can be attached to the application portion via the adhesive layer, and after attachment, the processing film is peeled off and removed.

[0101] The transparent conductive layer is formed, for example, so as to cover the entire surface of the heat-resistant resin layer (A). The transparent conductive layer can be patterned into a desired shape by an appropriate method such as etching. Note that a transparent conductive layer having a desired pattern shape may be formed on the heat-resistant resin layer (A) without undergoing a step such as etching by selectively disposing a transparent conductive material on the heat-resistant resin layer (A). Peeling and removing the casting film from the transparent conductive film results in poor handling, so it is preferable to peel and remove the casting film after applying the transparent conductive film to an application portion such as an adherend.

[0102] The thickness of the transparent conductive film can be appropriately determined depending on the intended use, etc. From the viewpoint of handleability, the substantial thickness of the transparent conductive film is preferably 0.3 to 50 μm, more preferably 0.5 to 25 μm, and even more preferably 0.7 to 12 μm. The term "substantial thickness" refers to the thickness in use. That is, although the transparent conductive film has a processing film, the thickness of the portion (such as the processing film) that is removed during use is not included in the "substantial thickness."

[0103] In this specification, the term "transparent" in the context of a transparent conductive film means that the light transmittance at a wavelength of 450 nm is 80% or more.

[0104] In the above transparent conductive film, when the heat-resistant resin layer (A) is a layer consisting of a cured product of a coating layer of a curable resin composition (C1) containing a polymer component (M) that is a polyimide resin and a curable monomer (P), the transparent conductive film has low birefringence and excellent optical isotropy. The in-plane retardation of the transparent conductive film is usually 20 nm or less, preferably 15 nm or less, more preferably 5 nm or less, and particularly preferably 1 nm or less. The thickness direction retardation is usually -500 nm or less, preferably -450 nm or less. The value obtained by dividing the in-plane retardation by the thickness of the transparent conductive film (birefringence) is usually 100 × 10 -5 or less, preferably 20 × 10 -5The following is the result. When the in-plane retardation, thickness direction retardation, and birefringence of the transparent conductive film are within the above ranges, the transparent conductive film has excellent optical isotropy and can be preferably used for optical applications.

[0105] The conductive material constituting the transparent conductive layer, the method for forming the transparent conductive layer, the thickness of the transparent conductive layer, etc. are as explained in the section "Functional Layer".

[0106] The transparent conductive film may further contain one or more other layers within the scope of the present invention. Examples of the other layers include an anti-reflection layer, a hard coat layer, an impact absorbing layer, an adhesive layer, etc. The positions of the other layers are not particularly limited.

[0107] [Transparent conductive film manufacturing method] The method for producing the transparent conductive film may include, for example, a method including the following steps 6 and 7. Step 6: A step of forming a conductive material layer on the heat-resistant resin layer (A) of the laminate obtained in step 2 or step 4. Step 7: A step of heating the conductive material layer obtained in step 6 to 100°C or higher to form a transparent conductive layer.

[0108] The method for producing the transparent conductive film may further include the following step 8. Step 8: A step of patterning the transparent conductive layer obtained in step 7 into a predetermined shape.

[0109] (Step 6) An electrically conductive material layer is disposed on the heat-resistant resin layer (A) of the laminate obtained in step 2 or step 4 above. The conductive material layer can be formed by, for example, a PVD method or a CVD method such as a sputtering method, an EB vapor deposition method, or an ion plating method. A method of forming the conductive material layer by applying a composition containing a conductive material and a solution onto the heat-resistant resin layer (A) and drying the composition can also be used. The conductive material layer is formed, for example, so as to cover the entire surface of the heat-resistant resin layer (A).

[0110] (Step 7) In step 7, the conductive material layer formed in step 6 is heated to 100°C or higher, preferably 140°C or higher, to crystallize the conductive material, thereby forming a transparent conductive layer, thereby obtaining a transparent conductive film. The conductive material layer can be heated by an electric furnace or the like.

[0111] The transparent conductive layer can be formed by various methods, but heating is required to crystallize the conductive material layer. Furthermore, when the conductive material layer is formed by coating, the conductive material-containing composition must be heated and dried after application. As described above, the heat-resistant resin layer (A) has a storage modulus of 0.01 to 100 GPa at 80°C, and the dimensional change rate in the MD of the cast film after heating at 150°C for 1 hour is 0.5% or less, so it is less susceptible to the effects of heating when forming the transparent conductive layer.

[0112] By continuously forming a conductive material layer on the heat-resistant resin layer (A) and heating it while transporting a long process film on which the heat-resistant resin layer (A) has been formed in a certain direction, a long laminate in which a transparent conductive layer has been formed on the heat-resistant resin layer (A) can be efficiently produced.

[0113] (Step 8) In step 8, a transparent conductive layer patterned into a desired shape is formed by removing a portion of the transparent conductive layer formed in step 7. Through step 8, a transparent conductive film having a patterned transparent conductive layer is obtained. As a method for patterning the transparent conductive layer, for example, a method can be adopted in which the portion corresponding to the desired shape is masked and then the transparent conductive layer is brought into contact with an etching solution to partially remove the transparent conductive layer, or unnecessary portions are removed by irradiating with a laser. In addition, a transparent conductive layer having a desired pattern shape may be formed on the heat-resistant resin layer (A) without undergoing a process such as etching by selectively placing a transparent conductive material on the heat-resistant resin layer (A) and heating it to form a transparent conductive layer.

[0114] After obtaining the transparent conductive film by the above steps, an adhesive layer may be provided on the transparent conductive layer. As is clear from the above description, the transparent conductive film obtained by the above production method is thin, has excellent heat resistance, excellent transparency and optical isotropy, and the transparent conductive layer has good electrical properties. [Example]

[0115] Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples in any way.

[0116] (i) The dimensional change rate of the laminates obtained in the Examples and Comparative Examples and the process film used to prepare the laminates, (ii) the peel force between the heat-resistant resin layer of the laminate and the process film, and (iii) the storage modulus, total light transmittance, and haze value of the heat-resistant resin layer contained in the laminate were measured by the following procedures.

[0117] (1) Storage modulus of laminate The processing film was peeled off from the laminates obtained in the Examples and Comparative Examples, and eight of the resulting heat-resistant resin layers were laminated together to form a 40 μm-thick test laminate. This test laminate was cut into 5 mm x 30 mm pieces to prepare test specimens. The test specimens were held in a thermomechanical analyzer (manufactured by Netsch Japan, product name "DMA242") with a chuck distance set to 15 mm. The test specimens were then heated from 25°C at a heating rate of 3°C / min, and the storage modulus at 80°C was measured.

[0118] (2) Total light transmittance and haze value of the heat-resistant resin layer The laminates obtained in the examples and comparative examples were cut into 50 mm x 50 mm pieces to prepare test pieces. The cast film was peeled off from the test pieces to obtain heat-resistant resin layers, and the total light transmittance (%) and haze value (%) were measured using a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., product name "SH-7000") in accordance with JIS K7136:2000. The test pieces were then subjected to a heat treatment (150°C, 1 hour) in an oven (manufactured by Espec Corporation, model name "SPHH202"), and the cast film was peeled off from the heat-treated test pieces to obtain heat-resistant resin layers, which were then measured for total light transmittance (%) and haze value (%) using the same method.

[0119] (3) Peel strength between the heat-resistant resin layer and the processing film The laminates prepared in the Examples and Comparative Examples were cut to a width of 50 mm and a length of 150 mm, and the heat-resistant resin layer side of each laminate was fixed to an aluminum plate (width 50 mm, length 150 mm, thickness 1 mm) with a double-sided adhesive film to prepare test specimens. Next, the heat-resistant resin layer of each test specimen was peeled from the processing film at a peel angle of 180° and a peel speed of 20 m / min using a high-speed peel tensile tester (manufactured by Tester Sangyo Co., Ltd., product name "High-Speed ​​Peel Tester TE-701") at 23°C and 50% relative humidity, and the peel force (mN / 50 mm) was measured. Furthermore, a separately prepared test piece was heated (150°C, 1 hour) in an oven (manufactured by Espec Corp., model name "SPHH202"), and the peel strength was measured in the same manner. The peel strength was calculated as the average of two measurements in accordance with JIS Z0237:2000.

[0120] (4) Dimensional change rate of laminate and process film The casting films used in the examples and comparative examples, and the laminates produced in the examples and comparative examples, were each cut into 100 mm squares to prepare test pieces. These test pieces were heated at 150°C for 1 hour, and the dimensional change rate was measured in accordance with JIS K7133 (1999). In the measurement, the arithmetic mean value of the dimensional change rates of two of the four sides of the test piece in the MD direction (the direction of the roll flow) was taken as the MD dimensional change rate, and the arithmetic mean value of the dimensional change rates of two of the four sides in the CD direction (the width direction of the roll) was taken as the CD dimensional change rate.

[0121] Example 1 -Laminate fabrication As the polymer component (M), 100 parts by mass of polyimide resin pellets (Kawamura Sangyo Co., Ltd., product name "KPI-MX300F", Tg = 354°C, weight average molecular weight 190,000) were dissolved in methyl ethyl ketone (MEK) to prepare a 15% by mass solution of polyimide resin. Next, 122 parts by mass of tricyclodecane dimethanol diacrylate (Shin-Nakamura Chemical Co., Ltd., A-DCP, molecular weight 304.4) as the curable monomer (P) and 5 parts by mass of (2,4,6-trimethylbenzoyl)-phenylphosphine oxide (GM Resins, Omnirad TPO) as the polymerization initiator were added to this solution and mixed to prepare a curable resin composition (C1). The curable monomer (P) and the polymerization initiator did not contain solvent, and all were raw materials with a solid content of 100%. Next, a polyethylene terephthalate (PET) film (manufactured by Toyobo Co., Ltd., product name "Cosmoshine A4100", thickness 50 μm) having an easy-adhesion layer on one side was prepared, and this PET film was annealed by heating at 150 ° C. for 30 minutes to obtain a processing film. The curable resin composition (C1) was applied to the surface opposite the easy-adhesion layer of this annealed PET processing film, and the resulting coating was dried by heating at 100 ° C. for 2 minutes. Then, a high-pressure mercury lamp (manufactured by iGraphics Co., Ltd., product name "H04-L41") was used to set the illuminance at 130 mW / cm with a light wavelength of 365 nm. 2 , light intensity 700mJ / cm 2A curing reaction was carried out by irradiating the resin with ultraviolet light under a nitrogen atmosphere using a Heraus UV actinometer (UV Power Puck (registered trademark) II) to form a heat-resistant resin layer with a thickness of 5 μm, thereby producing a laminate. The dimensional change rate and the peel strength between the heat-resistant resin layer and the casting film were measured for the resulting laminate. The storage modulus, total light transmittance, and haze value of the heat-resistant resin layer contained in the resulting laminate were also measured. Furthermore, the dimensional change rate of the casting film used to prepare the laminate was measured. The results are shown in Table 1.

[0122] Example 2 A commercially available annealed PET film with an oligomer block layer (manufactured by Aim Co., Ltd., product name "2000AF2·PET50csOB", ​​thickness 50 μm) was used as the casting film. A heat-resistant resin layer was formed on the casting film in the same manner as in Example 1, except that the curable resin composition (C1) was applied to the surface of the PET film opposite to the surface on which the oligomer block layer was formed, thereby producing a laminate. The dimensional change rate and the peel strength between the heat-resistant resin layer and the casting film were measured for the resulting laminate. The storage modulus, total light transmittance, and haze value of the heat-resistant resin layer contained in the resulting laminate were also measured. Furthermore, the dimensional change rate of the casting film used to prepare the laminate was measured. The results are shown in Table 1. Example 3 In the laminate produced in Example 2, a transparent conductive layer (thickness 100 nm) was formed on the heat-resistant resin layer by DC magnetron sputtering using an indium oxide target material (manufactured by Sumitomo Metal Mining Co., Ltd.) containing 10 mass % SnO2.

[0123] (Comparative Example 1) A laminate was prepared in the same manner as in Example 1, except that a polyethylene terephthalate (PET) film (manufactured by Toyobo Co., Ltd., product name "Cosmoshine A4100", thickness 50 μm) having an easy-adhesion layer on one side was used as the process film without annealing treatment. The dimensional change rate and the peel strength between the heat-resistant resin layer and the casting film were measured for the resulting laminate. The storage modulus, total light transmittance, and haze value of the heat-resistant resin layer contained in the resulting laminate were also measured. Furthermore, the dimensional change rate of the casting film used to prepare the laminate was measured. The results are shown in Table 1.

[0124] (Comparative Example 2) A laminate was produced in the same manner as in Example 1, except that a polyethylene terephthalate (PET) film (manufactured by Toyobo Co., Ltd., product name "Cosmoshine PET100A-4360", thickness 50 μm) having easy-adhesion layers on both sides was used as the processing film without annealing treatment. The dimensional change rates of the resulting laminate and the processing film used to prepare the laminate were measured, and the results are shown in Table 1. In the obtained laminate, the heat-resistant resin layer and the casting film were adhered to each other and could not be separated, so that physical properties other than the dimensional change rate could not be measured.

[0125] The chemical structural formulas of the curable monomers (P) used in the examples and comparative examples are shown below.

[0126] [ka]

[0127] [Table 1]

[0128] As shown in Table 1, in Example 1, an annealed PET film was used as the process film, and the dimensional change rate of this process film due to heat treatment (150°C, 1 hour) was low, so that the dimensional change rate in the MD direction of the laminate was a low value of 0.5% or less. In addition, in Example 2, an annealed PET film (with an oligomer precipitation prevention layer laminated on the back side) was used as the processing film, and the dimensional change rate of the processing film due to the heat treatment (150°C, 1 hour) was also low, and as a result, it was found that the dimensional change rate in the MD direction of the laminate was a low value of 0.5% or less. Furthermore, it is understood that in Example 3, even when a transparent electrode layer is formed on the laminate of Example 2, a dimensional change rate equal to or less than that of Example 2 can be obtained.

[0129] On the other hand, in Comparative Examples 1 and 2, unannealed PET film was used as the process film, and the dimensional change rate of these process films due to heat treatment (150°C, 1 hour) was high, which resulted in a high dimensional change rate of the laminate, particularly in the MD, the direction in which the residual stress during PET film formation was large, which was found to be significantly greater than 0.5%.

[0130] In Examples 1 and 2 and Comparative Example 1, the surface of the casting film that comes into contact with the heat-resistant resin layer is made of PET material itself (raw PET surface), and the peel force between the casting film and the heat-resistant resin layer is 500 mN / 50 mm or less before and after heating, allowing for easy peeling before and after heat treatment. In contrast, in Comparative Example 2, the surface of the casting film that comes into contact with the heat-resistant resin layer is an easy-adhesion layer, which means that the casting film and the heat-resistant resin layer adhere to each other, resulting in poor peeling. [Industrial Applicability]

[0131] The laminate of the present invention is provided with a heat-resistant resin layer having high optical properties and can suppress the occurrence of curling due to heat treatment, and is therefore expected to be applied to substrates of components constituting electronic devices such as display devices that require heat treatment in the manufacturing process, or components and substrates of optical films, for example, components constituting transparent conductive layers such as ITO used in flexible organic EL displays, liquid crystal displays, touch panels, etc., and substrates thereof, anti-reflection hard coat films, polarizer protective films for polarizing plates, etc. [Explanation of symbols]

[0132] 1, 11, 21, 31, 41: Laminate 2: Heat-resistant resin layer (A) 3: Processing film 3a: Release layer 4: Heat-resistant resin layer (B) 5: Functional layer

Claims

1. A casting film and a heat-resistant resin layer (A) are provided in this order, the heat-resistant resin layer (A) has a storage modulus at 80°C of 1.5 to 70 GPa; The thickness of the heat-resistant resin layer (A) is 1 μm or more and 7 μm or less, The laminate, wherein the dimensional change rate of the cast film in the machine direction when heated at 150°C for 1 hour is 0.5% or less.

2. 2. The laminate according to claim 1, wherein the heat-resistant resin layer (A) is a layer made of a cured product of a curable resin composition (C1) containing a polymer component (M) that is a polyimide resin and a curable monomer (P).

3. the casting film has a first surface facing the heat-resistant resin layer (A), 3. The laminate according to claim 1, wherein the first surface is peelable from the heat-resistant resin layer (A) and has a peel strength of 500 mN / 50 mm or less after heating at 150°C for 1 hour.

4. The laminate according to claim 1 or 2, further comprising a functional layer located on the surface of the heat-resistant resin layer (A) opposite to the surface facing the casting film.

5. A transparent conductive film comprising the laminate according to claim 1 or 2 and a transparent conductive layer provided on the heat-resistant resin layer (A) of the laminate.

6. 3. A method for producing a transparent conductive film, comprising: forming a conductive material layer on the heat-resistant resin layer (A) of the laminate according to claim 1 or 2; and heating the conductive material layer to 100°C or higher to form a transparent conductive layer.

Images