Transparent high heat resistant laminate film

Abstract

Provided is a transparent high-heat-resistant laminated film that has a sufficiently smooth surface when used as a substrate for a flexible device, and that is excellent in workability and in warpage suppression. The present invention is a transparent high-heat-resistant laminated film characterized by having (a) layer and (b) layer, and having a mixed layer at the interface between the (a) layer and the (b) layer, the mixed layer having a thickness of 3 μm or more. The (a) layer is a layer containing a polyimide composition, and the (b) layer is a layer containing a polyimide composition and having a higher inorganic filler content than the (a) layer.

Description

Technical Field

[0001] This invention relates to transparent, high-heat-resistant laminated films. Background Technology

[0002] In recent years, there has been active development in technology for forming functional components such as semiconductor devices, MEMS devices, and display devices on polymer films, aiming to achieve lightweighting, miniaturization / thinning, and flexibility. Specifically, ceramics, which are heat-resistant and capable of handling the high-frequency (GHz band) signals of information and communication devices, have been used as substrates for electronic components such as broadcasting equipment, wireless mobile devices, portable communication devices, radar, and high-speed information processing devices. However, ceramics suffer from limitations in application areas due to their lack of flexibility and difficulty in thinning. Therefore, polymer films have recently been used as substrates. Examples of polymer films used as flexible substrates include patent documents 1 and 2.

[0003] As substrate materials for manufacturing flexible electronic devices, the use of polymer films such as polyimide, aromatic polyamide, polyamide-imide, polycarbonate, polyethylene naphthalate, and polyethylene terephthalate is being investigated. Because these polymer films are manufactured in long rolls, they are generally considered ideal for roll-to-roll production lines in the manufacture of flexible devices. On the other hand, conventional electronic devices such as display devices, sensor arrays, touch screens, and printed wiring substrates mostly use rigid substrates such as glass substrates, semiconductor wafers, or glass fiber reinforced epoxy boards. Manufacturing apparatuses are also constructed based on the use of such rigid substrates. Therefore, in order to form functional elements into polymer films using existing infrastructure, the following process can be used: bonding the polymer film to a rigid support made of inorganic materials such as glass plates, ceramic plates, silicon wafers, or metal plates, forming the desired element on it, and then peeling it off from the support.

[0004] However, in the process of forming desired functional elements on a laminate consisting of a polymer film and an inorganic support, the laminate is often exposed to high temperatures. For example, the formation of functional elements such as polycrystalline silicon or oxide semiconductors requires processes in the temperature range of approximately 200°C to 600°C. Furthermore, in the fabrication of hydrogenated amorphous silicon thin films, temperatures of approximately 200°C to 300°C are sometimes applied to the film, and further heating and dehydrogenation of the amorphous silicon to form low-temperature polycrystalline silicon sometimes requires heating to approximately 450°C to 600°C. Therefore, the polymer film constituting the laminate requires heat resistance, but as a practical problem, the number of polymer films that can withstand practical use in this high-temperature region is limited. Existing technical documents Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2011-74384 Patent Document 2: International Publication No. 2012 / 118020 Summary of the Invention The problem that the invention aims to solve

[0006] In such applications, the surface of the heat-resistant film forming the functional element requires extremely high smoothness (absence of even a few μm of unevenness). On the other hand, a film with good smoothness has poor sliding properties when wound into a roll, making it difficult to ensure operability. One method to improve the sliding properties of the heat-resistant film is to add a lubricant composed of silica particles, etc. However, with the addition of the lubricant, the smoothness of the heat-resistant film surface is compromised. One method to solve this problem is to fabricate a two-layer laminate containing a lubricant layer and a layer without lubricant, using the layer without lubricant as the surface for forming the functional element. However, due to the subtle difference in surface and back-side properties caused by the addition of lubricant, the laminated film may warp.

[0007] The present invention was made in view of the problems described above. That is, the object of the present invention is to provide a laminated film that has a sufficiently smooth surface when used as a substrate for flexible devices, and has good operability and suppresses warping.

[0008] The inventors have conducted in-depth research on the suppression of warpage in transparent high-heat-resistant laminated films. Their findings revealed that in transparent high-heat-resistant laminated films composed of layers with varying lubricant dosages, if the thickness of the interlayer mixing layer is 3 μm or more, warpage can be suppressed to below 700 μm. This invention was completed based on this discovery. That is, the present invention is as follows.

[0009] [1] A transparent, high-heat-resistant laminated film, characterized in that it has a (a) layer and a (b) layer, A hybrid layer is present at the interface between layer (a) and layer (b). The thickness of the hybrid layer is 3 μm or more. (a) Layer: A layer containing a polyimide composition. (b) layer: a layer containing a polyimide composition and having a higher content of inorganic filler than layer (a). [2] The transparent high heat-resistant laminated film according to [1] is characterized in that the content of inorganic filler in layer (a) is less than 0.03% by mass. [3] The transparent high heat-resistant laminated film according to [1] or [2] is characterized in that the content of inorganic filler in layer (b) is 0.03% by mass or more. [4] The transparent high heat-resistant laminated film according to any one of [1] to [3] is characterized in that the thickness of the transparent high heat-resistant laminated film is more than 5 μm and less than 200 μm. [5] The transparent high heat-resistant laminate according to any one of [1] to [4] is characterized in that all layers comprising the (a) layer and the (b) layer constituting the transparent high heat-resistant laminate contain a polyimide composition. [6] The transparent high heat-resistant laminated film according to any one of [1] to [5] is characterized in that the transparent high heat-resistant laminated film is composed only of the (a) layer, the mixed layer and the (b) layer. [7] A laminate, characterized in that it is a laminate of a transparent high heat-resistant laminate and an inorganic substrate, which does not substantially use an adhesive, as described in any one of [1] to [6], wherein the peel strength between the inorganic substrate and the transparent high heat-resistant laminate after heating at 300°C is less than 0.3 N / cm. [8] A method for manufacturing a film with electronic devices, wherein electronic devices are formed on a transparent, heat-resistant laminate of the laminate described in [7], and then peeled off from an inorganic substrate. Invention Effects

[0010] According to the present invention, due to the good operability of the transparent high heat-resistant laminated film, it is easy to provide a surface-smooth film for use in roll-to-roll processes. Furthermore, warpage of the resulting transparent high heat-resistant laminated film is suppressed, and stress is less likely to be applied to the device after it has been formed on the surface. Attached Figure Description

[0011] [ Figure 1 ] Figure 1 This is a schematic diagram used to illustrate the silane coupling agent coating method involved in this patent. Detailed Implementation

[0012] The embodiments of the present invention will be described below.

[0013] <Transparent High Heat Resistance Laminated Film> In this application specification, the term "transparent high heat-resistant laminated film" refers to a film with a preferred melting point of 250°C or higher, more preferably 300°C or higher, and even more preferably 400°C or higher. Furthermore, it refers to a film made of a polymer with a preferred glass transition temperature of 200°C or higher, more preferably 320°C or higher, and even more preferably 350°C or higher. Hereinafter, for the sake of simplicity, it will be simply referred to as a polymer film. In this application specification, the melting point and glass transition temperature are determined by differential thermal analysis (DSC). It should be noted that when the melting point exceeds 500°C, the degree of melting can be determined by visually observing the thermal deformation behavior when heated at that temperature.

[0014] Furthermore, regarding transparency, a total light transmittance of 75% or more is preferred. More preferably, it is 80% or more, further preferably 85% or more, even more preferably 87% or more, and particularly preferably 88% or more. There is no particular upper limit to the total light transmittance of the aforementioned transparent, high-heat-resistant laminated film; however, for use as a film with electronic components (hereinafter also referred to as flexible electronic components), it is preferably 98% or less, more preferably 97% or less.

[0015] Examples of the aforementioned transparent, high-heat-resistant films (hereinafter also referred to as polymer films) include: polyimide resins such as polyimide, polyamide-imide, polyether-imide, and fluorinated polyimide (e.g., aromatic polyimide resins and alicyclic polyimide resins); copolyesters such as polyethylene, polypropylene, polyethylene terephthalate, polyethylene terephthalate, and polyethylene 2,6-naphthalate (e.g., fully aromatic polyesters and semi-aromatic polyesters); copoly(meth)acrylates represented by polymethyl methacrylate; polycarbonate; polyamide; polysulfone; polyethersulfone; polyetherketone; cellulose acetate; cellulose nitrate; aromatic polyamide; polyvinyl chloride; polyphenols; polyarylates; polyacetal; modified polyphenylene ether; polyphenylene sulfide; polyphenylene ether; polystyrene; polybenzoxazole; polybenzothiazole; polybenzimidazole; cyclic polyolefins; and liquid crystal polymers. In addition, examples can be given of membranes obtained by reinforcing these with glass fillers, glass fibers, etc. However, since the aforementioned polymer films are designed for processes involving heat treatment at temperatures above 250°C, the practical applications of the illustrated polymer films are limited. Preferably, the polymer films used are made of so-called super engineering plastics; more specifically, examples include aromatic polyimide films, alicyclic polyimide films, aromatic amide films, aromatic amide-imide films, amide-imide films, aromatic benzoxazole films, aromatic benzothiazole films, aromatic benzimidazole films, cyclic polyolefins, and liquid crystal polymers.

[0016] The following is a detailed description of an example of the aforementioned polymer membrane, a polyimide-based resin membrane (sometimes also called a polyimide membrane). Typically, polyimide-based resin membranes are obtained by: coating a polyamic acid (polyimide precursor) solution, obtained by reacting a diamine and a tetracarboxylic acid in a solvent, onto a support for making a polyimide membrane; drying to form a green membrane (hereinafter also called a "precursor membrane" or "polyamic acid membrane"); and further subjecting the green membrane to a high-temperature heat treatment for dehydration and ring-closing reaction on or peeled from the support for making a polyimide membrane. Here, the green membrane refers to a membrane containing a solvent and possessing self-supporting polyamic acid properties. The solvent content of the green membrane is not particularly limited as long as it possesses self-supporting properties, but is preferably 1% by mass or more, more preferably 5% by mass or more, further preferably 10% by mass or more, even more preferably 20% by mass or more, and particularly preferably 30% by mass or more. Furthermore, it is preferably 80% by mass or less, more preferably 70% by mass or less, further preferably 60% by mass or less, and particularly preferably 50% by mass or less.

[0017] Regarding the coating of polyamic acid (polyimide precursor) solutions, conventionally known solution coating methods such as spin coating, doctor blade coating, coater coating, comma coater, screen printing, slot coating, reverse coating, dip coating, curtain coating, and slot die coating can be appropriately used. In methods for fabricating films by coating polyamic acid solutions, the wide range of material choices facilitates research into preferred materials for easy peeling; however, the imidization reaction must be controlled. In contrast, the fabrication of films without imidization reactions offers the advantage of ease of film fabrication and must therefore be appropriately differentiated and used.

[0018] In this invention, the polyimide film is a polymer film with imide bonds on its main chain, preferably a polyimide film, a polyamide-imide film, and more preferably a polyimide film. Additionally, a polyamide film is also preferred.

[0019] Typically, as described above, polyimide films are obtained by: coating a polyamic acid (polyimide precursor) solution obtained by reacting a diamine and a tetracarboxylic acid in a solvent onto a support for making polyimide films, drying to form a green film, and further subjecting the green film to a high-temperature heat treatment for dehydration and ring-closure reaction while on or peeled from the support. Alternatively, polyimide films can be obtained by: coating a polyimide solution obtained by a dehydration and ring-closure reaction of a diamine and a tetracarboxylic acid in a solvent onto a support for making polyimide films and drying to form, for example, a polyimide film containing 1 to 50% by mass of solvent; and further subjecting the polyimide film containing 1 to 50% by mass of solvent to a high-temperature heat treatment for drying while on or peeled from the support.

[0020] In addition, polyamide-imide films are typically obtained by: coating a polyamide-imide solution obtained by reacting diisocyanates and tricarboxylic acids in a solvent onto a support for making polyamide-imide films and drying it to form, for example, a polyamide-imide film containing 1 to 50% by mass of solvent; and further drying the polyamide-imide film containing 1 to 50% by mass of solvent at high temperature while it is on or peeled off from the support for making polyamide-imide films.

[0021] In addition, polyamide films are usually obtained by: coating a polyamide solution obtained by reacting a diamine and a dicarboxylic acid in a solvent onto a support for making a polyamide film and drying it to form a polyamide film containing, for example, 1 to 50% by mass of solvent; and further drying the polyamide film containing 1 to 50% by mass of solvent at high temperature while it is on or peeled off from the support for making a polyamide film.

[0022] As the aforementioned tetracarboxylic acids, tricarboxylic acids, and dicarboxylic acids, aromatic tetracarboxylic acids (including their anhydrides), aliphatic tetracarboxylic acids (including their anhydrides), alicyclic tetracarboxylic acids (including their anhydrides), aromatic tricarboxylic acids (including their anhydrides), aliphatic tricarboxylic acids (including their anhydrides), alicyclic tricarboxylic acids (including their anhydrides), aromatic dicarboxylic acids, aliphatic dicarboxylic acids, and alicyclic dicarboxylic acids can be used. Among these, aromatic tetracarboxylic anhydrides and aliphatic tetracarboxylic anhydrides are preferred; from the viewpoint of heat resistance, aromatic tetracarboxylic anhydrides are more preferred; from the viewpoint of light transmittance, alicyclic tetracarboxylic acids are more preferred. When the tetracarboxylic acid is an anhydride, the anhydride structure within the molecule can be one or two, and an anhydride (dianhydride) with two anhydride structures is preferred. Tetracarboxylic acids, tricarboxylic acids, and dicarboxylic acids can be used alone or in combination of two or more.

[0023] Examples of aromatic tetracarboxylic acids used to obtain the colorless and highly transparent polyimide of this invention include 4,4'-(2,2-hexafluoroisopropyl)diphthalic acid, 4,4'-oxydiphthalic acid, bis(1,3-dioxo-1,3-dihydro-2-benzofuran-5-carboxylic acid)1,4-phenylene, bis(1,3-dioxo-1,3-dihydro-2-benzofuran-5-yl)phenyl-1,4-dicarboxylic acid, 4,4'-[4,4'-(3-oxo-1,3-dihydro-2-benzofuran-1,1-diyl)bis(phenyl-1,4-diyloxy)]diphenyl-1,2-dicarboxylic acid, 3,3',4,4'-benzophenone tetracarboxylic acid, and 4,4'-[(3-oxo-1,3-dihydro-2-benzofuran-1,1-diyl)bis(benzo-1,4-diyloxy)]diphenyl-1,2-dicarboxylic acid, 3,3',4,4'-benzophenone tetracarboxylic acid, and 4,4'-[(3-oxo-1,3-dihydro-2-benzofuran-1,1-diyl)bis(benzo-1,4-diyloxy)]diphenyl-1,2-dicarboxylic acid. -benzofuran-1,1-diyl)bis(toluene-2,5-dioxy)]diphenyl-1,2-dicarboxylic acid, 4,4'-[(3-oxo-1,3-dihydro-2-benzofuran-1,1-diyl)bis(1,4-xylene-2,5-dioxy)]diphenyl-1,2-dicarboxylic acid, 4,4'-[4,4'-(3-oxo-1,3-dihydro-2-benzofuran-1,1-diyl)bis(4-isopropyl-toluene-2,5-dioxy)]diphenyl-1,2-dicarboxylic acid, 4,4'-[4,4'-(3-oxo-1,3-dihydro-2-benzofuran-1,1-diyl)bis(4-isopropyl-toluene-2,5-dioxy)]diphenyl-1,2-dicarboxylic acid, 4,4'-[4,4'-(3H -2,1-Benzothiapentane-1,1-dioxide-3,3-diyl)bis(benzyl-1,4-diyloxy)]diphenyl-1,2-dicarboxylic acid, 4,4'-benzophenone tetracarboxylic acid, 4,4'-[(3H-2,1-benzothiapentane-1,1-dioxide-3,3-diyl)bis(toluene-2,5-diyloxy)]diphenyl-1,2-dicarboxylic acid, 4,4'-[(3H-2,1-benzothiapentane-1,1-dioxide-3,3-diyl)bis(1,4-xylene-2,5-diyloxy)]diphenyl-1,2-dicarboxylic acid, 4,4'-[4,4'-(3H-2,1-benzothiapentane-1,1-dioxide-3,3-diyl)bis(4-isopropyl) [-toluene-2,5-dioxy]diphenyl-1,2-dicarboxylic acid, 4,4'-[4,4'-(3H-2,1-benzoxythiapentane-1,1-dioxide-3,3-diyl)bis(naphthalene-1,4-dioxy)]diphenyl-1,2-dicarboxylic acid, 3,3',4,4'-benzophenone tetracarboxylic acid, 3,3',4,4'-benzophenone tetracarboxylic acid, 3,3',4,4'-diphenylsulfone tetracarboxylic acid, 3,3',4,4'-biphenyltetracarboxylic acid, 2,3,3',4'-biphenyltetracarboxylic acid, 2,2',3,3'-biphenyltetracarboxylic acid, 2,2'-diphenoxy-4,4',5,5'-biphenyltetracarboxylic acid, pyromellitic acid, 4,4'-[spiro(xanthan-9,9'-fluorene)-2,Tetracarboxylic acids such as 6-dimethylbis(oxycarbonyl)] phthalic acid, 4,4'-[spiro(xanthon-9,9'-fluorene)-3,6-dimethylbis(oxycarbonyl)] phthalic acid, and their anhydrides are preferred. Among these, dianhydrides having two anhydride structures are preferred, particularly 4,4'-(2,2-hexafluoroisopropylidene) phthalic acid dianhydride and 4,4'-oxyphthalic acid dianhydride. It should be noted that aromatic tetracarboxylic acids can be used alone or in combination of two or more. Regarding the copolymerization amount of aromatic tetracarboxylic acids, when heat resistance is important, it is preferably 50% by mass or more of the total carboxylic acids, more preferably 60% by mass or more, further preferably 70% by mass or more, and even more preferably 80% by mass or more.

[0024] Examples of alicyclic tetracarboxylic acids include 1,2,3,4-cyclobutanetetracarboxylic acid, 1,2,3,4-cyclopentanetetracarboxylic acid, 1,2,3,4-cyclohexanetetracarboxylic acid, 1,2,4,5-cyclohexanetetracarboxylic acid, 3,3',4,4'-bicyclohexyltetracarboxylic acid, bicyclo[2,2,1]heptane-2,3,5,6-tetracarboxylic acid, bicyclo[2,2,2]octane-2,3,5,6-tetracarboxylic acid, bicyclo[2,2,2]oct-7-ene-2,3,5,6-tetracarboxylic acid, tetrahydroanthracene-2,3,6,7-tetracarboxylic acid, tetradecahydro-1,4:5,8:9,10-trimethanoanthracene-2,3,6,7-tetracarboxylic acid, and decahydronaphthalene-2,3,6,7-tetracarboxylic acid. -Tetracarboxylic acid, decahydro-1,4:5,8-dimethanonaphthalene-2,3,6,7-tetracarboxylic acid, decahydro-1,4-ethionophthalene-2,3,6,7-tetracarboxylic acid, norbornane-2-spiro-α-cyclopentanone-α'-spiro-2"-norbornane-5,5",6,6"-tetracarboxylic acid (also known as "norbornane-2-spiro-2'-cyclopentanone-5'-spiro-2"-norbornane-5,5",6,6"-tetracarboxylic acid"), methylnorbornane-2-spiro-α-cyclopentanone-α'-spiro-2"-(methylnorbornane)-5,5",6,6"-tetracarboxylic acid, norbornane-2- Spiro-α-cyclohexanone-α'-spiro-2"-norbornane-5,5",6,6"-tetracarboxylic acid (also known as "norbornane-2-spiro-2'-cyclohexanone-6'-spiro-2"-norbornane-5,5",6,6"-tetracarboxylic acid"), methylnorbornane-2-spiro-α-cyclohexanone-α'-spiro-2"-(methylnorbornane)-5,5",6,6"-tetracarboxylic acid, norbornane-2-spiro-α-cyclopropanone-α'-spiro-2"-norbornane-5,5",6,6"-tetracarboxylic acid, norbornane-2-spiro-α-cyclobutanone-α'-spiro-2"-norbornane-5,5",6,6"-tetracarboxylic acid, norbornane-2-spiro-α-cycloheptanone-α'-spiro-2"-norbornane-5,5",6,6"-tetracarboxylic acid, norbornane-2-spiro-α-cycloheptanone-α'-spiro-2"-norbornane-5,5",6 6"-Tetracarboxylic acid, norbornane-2-spiro-α-cyclooctanone-α'-spiro-2"-norbornane-5,5",6,6"-tetracarboxylic acid, norbornane-2-spiro-α-cyclononanone-α'-spiro-2"-norbornane-5,5",6,6"-tetracarboxylic acid, norbornane-2-spiro-α-cyclodecanone-α'-spiro-2"-norbornane-5,5",6,6"-tetracarboxylic acid, norbornane-2-spiro-α-cycloundecanone-α'-spiro-2"-norbornane-5,5",6,6"-tetracarboxylic acid, norbornane-2-spiro-α-cyclododecanone-α'-spiro-2"-norbornane-5,5",6,6"-tetracarboxylic acid, norbornane-2-spiro-α-cyclododecanone-α'-spiro-2"-norbornane-5,Tetracarboxylic acids such as 5",6,6"-tetracarboxylic acid, norbornane-2-spiro-α-cyclotetradecadecanone-α'-spiro-2"-norbornane-5,5",6,6"-tetracarboxylic acid, norbornane-2-spiro-α-cyclopentadecanone-α'-spiro-2"-norbornane-5,5",6,6"-tetracarboxylic acid, norbornane-2-spiro-α-(methylcyclopentanone)-α'-spiro-2"-norbornane-5,5",6,6"-tetracarboxylic acid, norbornane-2-spiro-α-(methylcyclohexanone)-α'-spiro-2"-norbornane-5,5",6,6"-tetracarboxylic acid, and their anhydrides. In addition, bilayer silsesquioxane derivatives containing anhydride groups represented by formula (1) can also be cited. Among these, dianhydrides having two anhydride structures are preferred, particularly 1,2,3,4-cyclobutanetetracarboxylic acid dianhydrides, 1,2,3,4-cyclohexanetetracarboxylic acid dianhydrides, and 1,2,4,5-cyclohexanetetracarboxylic acid dianhydrides, more preferably 1,2,3,4-cyclobutanetetracarboxylic acid dianhydrides, and even more preferably 1,2,3,4-cyclobutanetetracarboxylic acid dianhydrides. It should be noted that these can be used alone or in combination of two or more. When transparency is important, the copolymerization amount of the alicyclic tetracarboxylic acid is preferably 50% by mass or more of the total tetracarboxylic acid, more preferably 60% by mass or more, even more preferably 70% by mass or more, and even more preferably 80% by mass or more. [Chemical Formula 1]

[0025] Examples of tricarboxylic acids include aromatic tricarboxylic acids such as trimellitic acid, 1,2,5-naphthalenetricarboxylic acid, diphenyl ether-3,3',4'-tricarboxylic acid, and diphenyl sulfone-3,3',4'-tricarboxylic acid, or hydrides of the aforementioned aromatic tricarboxylic acids such as hexahydrotriphenylamine, alkylene glycol bis(triphenylamine) esters such as ethylene glycol bis(triphenylamine) ester, propylene glycol bis(triphenylamine) ester, 1,4-butanediol bis(triphenylamine) ester, and polyethylene glycol bis(triphenylamine) ester, as well as their monohydric anhydrides and esterifications. Among these, monohydric anhydrides having one anhydride structure are preferred, and in particular, trimellitic anhydride and hexahydrotriphenylamine anhydride are preferred. It should be noted that these can be used alone or in combination.

[0026] Examples of dicarboxylic acids include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, and 4,4'-oxybenzoic acid, or hydrides of the aforementioned aromatic dicarboxylic acids such as 1,6-cyclohexanedicarboxylic acid; oxalic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, octanoic acid, azelaic acid, sebacic acid, undecanoic acid, dodecanoic acid, 2-methylsuccinic acid, and their acyl chlorides or esters. Among these, aromatic dicarboxylic acids and their hydrides are preferred, especially terephthalic acid, 1,6-cyclohexanedicarboxylic acid, and 4,4'-oxybenzoic acid. It should be noted that dicarboxylic acids can be used alone or in combination.

[0027] There are no particular limitations on the diamines or isocyanates used to obtain the colorless and highly transparent polyimide of this invention. Aromatic diamines, aliphatic diamines, alicyclic diamines, aromatic diisocyanates, aliphatic diisocyanates, and alicyclic diisocyanates commonly used in polyimide synthesis, polyamide-imide synthesis, and polyamide synthesis can be used. From the viewpoint of heat resistance, aromatic diamines are preferred, and from the viewpoint of transparency, alicyclic diamines are preferred. Furthermore, if an aromatic diamine with a benzoxazole structure is used, it can exhibit high heat resistance, as well as high elastic modulus, low heat shrinkage, and low coefficient of linear expansion. Diamines and isocyanates can be used alone or in combination of two or more.

[0028] Examples of aromatic diamines include 2,2'-dimethyl-4,4'-diaminobiphenyl, 1,4-bis[2-(4-aminophenyl)-2-propyl]benzene, 1,4-bis(4-amino-2-trifluoromethylphenoxy)benzene, 2,2'-bistrifluoromethyl-4,4'-diaminobiphenyl, 4,4'-bis(4-aminophenoxy)biphenyl, 4,4'-bis(3-aminophenoxy)biphenyl, bis[4-(3-aminophenoxy)phenyl]ketone, bis[4-(3-aminophenoxy)phenyl]sulfide, bis[4-(3-aminophenoxy)phenyl]sulfone, 2,2-bis[4-(3-aminophenoxy)phenyl]propane, and 2,2-bis[4-(3-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoro Propane, m-phenylenediamine, o-phenylenediamine, p-phenylenediamine, m-aminobenzylamine, p-aminobenzylamine, 4-amino-N-(4-aminophenyl)benzamide, 3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 2,2'-trifluoromethyl-4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl sulfide, 3,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfoxide, 3,4'-diaminodiphenyl sulfoxide, 4,4'-diaminodiphenyl sulfoxide, 3,3'-diaminodiphenyl sulfone, 3,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl ketone, 3,4'-diaminodiphenyl ketone, 4, 4'-Diaminobenzophenone, 3,3'-Diaminodiphenylmethane, 3,4'-Diaminodiphenylmethane, 4,4'-Diaminodiphenylmethane, bis[4-(4-aminophenoxy)phenyl]methane, 1,1-bis[4-(4-aminophenoxy)phenyl]ethane, 1,2-bis[4-(4-aminophenoxy)phenyl]ethane, 1,1-bis[4-(4-aminophenoxy)phenyl]propane, 1,2-bis[4-(4-aminophenoxy)phenyl]propane, 1,3-bis[4-(4-aminophenoxy)phenyl]propane, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 1,1-bis[4-(4-aminophenoxy)phenyl]butane, 1,3-bis[4-(4-aminophenoxy)phenyl]butane [Phenylacetane]butane, 1,4-bis[4-(4-aminophenoxy)phenyl]butane, 2,2-bis[4-(4-aminophenoxy)phenyl]butane, 2,3-bis[4-(4-aminophenoxy)phenyl]butane, 2-[4-(4-aminophenoxy)phenyl]-2-[4-(4-aminophenoxy)-3-methylphenyl]propane, 2,2-bis[4-(4-aminophenoxy)-3-methylphenyl]propane, 2-[4-(4-aminophenoxy)phenyl]-2-[4-(4-aminophenoxy)-3,5-dimethylphenyl]propane, 2,2-bis[4-(4-aminophenoxy)-3,5-dimethylphenyl]propane, 2,2-bis[4-(4-aminophenoxy)-3,5-dimethylphenyl]propane, 2,2-bis[4-(4-aminophenoxy)phenyl]-1,1,1,3,3,3-Hexafluoropropane, 1,4-bis(3-aminophenoxy)benzene, 1,3-bis(3-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 4,4'-bis(4-aminophenoxy)biphenyl, bis[4-(4-aminophenoxy)phenyl]ketone, bis[4-(4-aminophenoxy)phenyl]sulfide, bis[4-(4-aminophenoxy)phenyl]sulfoxide, bis[4-(4-aminophenoxy)phenyl]sulfone, bis[4-(3-aminophenoxy)phenyl]ether, bis[4-(4-aminophenoxy)phenyl]ether, 1,3-bis[4-(4-aminophenoxy)benzoyl]benzene, 1,3-bis[4-(3-aminophenoxy)benzoyl]benzene, 1,4-bis[4-(3-aminophenoxy)benzoyl]benzene [3-aminophenoxy)benzoyl]benzene, 4,4'-bis[(3-aminophenoxy)benzoyl]benzene, 1,1-bis[4-(3-aminophenoxy)phenyl]propane, 1,3-bis[4-(3-aminophenoxy)phenyl]propane, 3,4'-diaminodiphenyl sulfide, 2,2-bis[3-(3-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, bis[4-(3-aminophenoxy)phenyl]methane, 1,1-bis[4-(3-aminophenoxy)phenyl]ethane, 1,2-bis[4-(3-aminophenoxy)phenyl]ethane, bis[4-(3-aminophenoxy)phenyl]sulfoxide, 4,4'-bis[3-(3-aminophenoxy)benzoyl]diphenyl ether, 4,4'-bis[3-( 3-Aminophenoxy)benzoyl]diphenyl ether, 4,4'-bis[4-(4-amino-α,α-dimethylbenzyl)phenoxy]benzophenone, 4,4'-bis[4-(4-amino-α,α-dimethylbenzyl)phenoxy]diphenyl sulfone, bis[4-{4-(4-aminophenoxy)phenoxy}phenyl]sulfone, 1,4-bis[4-(4-aminophenoxy)phenoxy-α,α-dimethylbenzyl]benzene, 1,3-bis[4-(4-aminophenoxy)phenoxy-α,α-dimethylbenzyl]benzene, 1,3-bis[4-(4-aminophenoxy)phenoxy-α,α-dimethylbenzyl]benzene, 1,3-bis[4-(4-amino-6-trifluoromethylphenoxy)-α,α-dimethylbenzyl]benzene, 1,3-bis[4-(4-amino-6-fluorophenoxy)-α,α-dimethylbenzyl]benzene, 1,3 -Bis[4-(4-amino-6-methylphenoxy)-α,α-dimethylbenzyl]benzene, 1,3-bis[4-(4-amino-6-cyanophenoxy)-α,α-dimethylbenzyl]benzene, 3,3'-diamino-4,4'-diphenoxybenzophenone, 4,4'-diamino-5,5'-diphenoxybenzophenone, 3,4'-diamino-4,5'-diphenoxybenzophenone, 3,3'-diamino-4-phenoxybenzophenone, 4,4'-diamino-5-phenoxybenzophenone, 3,4'-diamino-4-phenoxybenzophenone, 3,4'-diamino-5'-phenoxybenzophenone, 3,3'-diamino-4,4'-dibiphenoxybenzophenone, 4,4'-diamino-55'-Diphenyloxybenzophenone, 3,4'-Diamino-4,5'-Diphenyloxybenzophenone, 3,3'-Diamino-4-Biphenyloxybenzophenone, 4,4'-Diamino-5-Biphenyloxybenzophenone, 3,4'-Diamino-4-Biphenyloxybenzophenone, 3,4'-Diamino-5'-Biphenyloxybenzophenone, 1,3-Bis(3-amino-4-phenoxybenzoyl) Benzene, 1,4-bis(3-amino-4-phenoxybenzoyl)benzene, 1,3-bis(4-amino-5-phenoxybenzoyl)benzene, 1,4-bis(4-amino-5-phenoxybenzoyl)benzene, 1,3-bis(3-amino-4-biphenoxybenzoyl)benzene, 1,4-bis(3-amino-4-biphenoxybenzoyl)benzene, 1,3-bis(4-amino-5-biphenoxybenzoyl)benzene, 1,4-bis(4-amino-5-biphenoxybenzoyl)benzene, 2,6-bis[4-(4-amino-α,α-dimethylbenzyl)phenoxy]benzylnitrile, 4,4'-[9H-fluorene-9,9-diyl]bisaniline (also known as "9,9-bis(4-aminophenyl)fluorene"), spiro(xanthan-9,9'-fluorene)-2,6-diylbis(oxycarbonyl)]bisaniline, 4,4'-[spiro(xanthan-9,9'-fluorene)-2,6-diylbis(oxycarbonyl)]bisaniline, [-9,9'-fluorene)-2,6-dimethylbis(oxycarbonyl)]bisaniline, 4,4'-[spiro(xanthan-9,9'-fluorene)-3,6-dimethylbis(oxycarbonyl)]bisaniline, 9,10-bis(4-aminophenyl)adenine, 2,4-bis(4-aminophenyl)cyclobutane-1,3-dicarboxylic acid dimethyl ester, and amino-containing bilayer silsesquioxane derivatives represented by the structure of formula (2), etc. Furthermore, some or all of the hydrogen atoms on the aromatic ring of the above-mentioned aromatic diamines may be substituted with halogen atoms, alkyl or alkoxy groups having 1 to 3 carbon atoms, or cyano groups, and furthermore, some or all of the hydrogen atoms on the alkyl or alkoxy groups having 1 to 3 carbon atoms may be substituted with halogen atoms. Furthermore, there are no particular limitations on the aforementioned aromatic diamines having the benzoxazole structure; examples include 5-amino-2-(p-aminophenyl)benzoxazole, 6-amino-2-(p-aminophenyl)benzoxazole, 5-amino-2-(m-aminophenyl)benzoxazole, 6-amino-2-(m-aminophenyl)benzoxazole, 2,2'-p-phenylenebis(5-aminobenzoxazole), 2,2'-p-phenylenebis(6-aminobenzoxazole), and 1-(5-aminobenzoxazole)-4-(6-aminobenzoxazole). Benzene, 2,6-(4,4'-diaminodiphenyl)benzo[1,2-d:5,4-d']bisoxazole, 2,6-(4,4'-diaminodiphenyl)benzo[1,2-d:4,5-d']bisoxazole, 2,6-(3,4'-diaminodiphenyl)benzo[1,2-d:5,4-d']bisoxazole, 2,6-(3,4'-diaminodiphenyl)benzo[1,2-d:4,5-d']bisoxazole, 2,6-(3,3'-diaminodiphenyl)benzo[1,2-d:5,[4-d']bisoxazole, 2,6-(3,3'-diaminodiphenyl)benzo[1,2-d:4,5-d']bisoxazole, etc. Among these, 2,2'-bistrifluoromethyl-4,4'-diaminobiphenyl, 4-amino-N-(4-aminophenyl)benzamide, 4,4'-diaminodiphenyl sulfone, and 3,3'-diaminobenzophenone are particularly preferred. It should be noted that aromatic diamines can be used alone or in combination. [Chemical Formula 2]

[0029] Examples of alicyclic diamines include 1,4-cyclohexanediamine, 1,4-diamino-2-methylcyclohexane, 1,4-diamino-2-ethylcyclohexane, 1,4-diamino-2-n-propylcyclohexane, 1,4-diamino-2-isopropylcyclohexane, 1,4-diamino-2-n-butylcyclohexane, 1,4-diamino-2-isobutylcyclohexane, 1,4-diamino-2-sec-butylcyclohexane, 1,4-diamino-2-tert-butylcyclohexane, and 4,4'-methylenebis(2,6-dimethylcyclohexylamine). Among these, 1,4-cyclohexanediamine and 1,4-diamino-2-methylcyclohexane are particularly preferred, and 1,4-cyclohexanediamine is more preferred. It should be noted that alicyclic diamines can be used alone or in combination.

[0030] Examples of diisocyanates include diphenylmethane-2,4'-diisocyanate, 3,2'- or 3,3'- or 4,2'- or 4,3'- or 5,2'- or 5,3'- or 6,2'- or 6,3'-dimethyldiphenylmethane-2,4'-diisocyanate, and 3,2'- or 3,3'- or 4,2'- or 4,3'- or 5,2'- or 5,3'- or 6,2'- or 6,3'-diethyldiphenylmethane- 2,4'-diisocyanate, 3,2'- or 3,3'- or 4,2'- or 4,3'- or 5,2'- or 5,3'- or 6,2'- or 6,3'-dimethoxydiphenylmethane-2,4'-diisocyanate, diphenylmethane-4,4'-diisocyanate, diphenylmethane-3,3'-diisocyanate, diphenylmethane-3,4'-diisocyanate, diphenyl ether-4,4'-diisocyanate, benzophenone-4,4'- Diisocyanate, diphenyl sulfone-4,4'-diisocyanate, toluene-2,4-diisocyanate, toluene-2,6-diisocyanate, m-xylene diisocyanate, p-xylene diisocyanate, naphthalene-2,6-diisocyanate, 4,4'-(2,2-bis(4-phenoxyphenyl)propane)diisocyanate, 3,3'- or 2,2'-dimethylbiphenyl-4,4'-diisocyanate, 3,3'- or 2,2'-diethylbiphenyl-4,4'-diisocyanate Aromatic diisocyanates such as '-diisocyanate, 3,3'-dimethoxybiphenyl-4,4'-diisocyanate, and 3,3'-diethoxybiphenyl-4,4'-diisocyanate, as well as diisocyanates formed by hydrogenation of any of them (e.g., isophorone diisocyanate, 1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, hexamethylene diisocyanate), etc. Among these, considering low hygroscopicity, dimensional stability, price, and polymerizability, diphenylmethane-4,4'-diisocyanate, toluene-2,4-diisocyanate, toluene-2,6-diisocyanate, 3,3'-dimethylbiphenyl-4,4'-diisocyanate, naphthalene-2,6-diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, and 1,4-cyclohexane diisocyanate are preferred. It should be noted that diisocyanates can be used alone or in combination.

[0031] The transparent, high-heat-resistant laminated film of the present invention comprises a layer (a) and a layer (b). That is, it is a film formed by laminating at least two layers, a layer (a) and a layer (b). The layer (a) is a layer containing a polyimide composition, and the layer (b) is a layer containing a polyimide composition but with a higher content of inorganic filler than the layer (a). The content of inorganic filler in the layer (a) is not particularly limited, but is preferably less than 0.03% by mass, more preferably less than 0.02% by mass, even more preferably less than 0.01% by mass, or may be 0% by mass. When the content of inorganic filler in the layer (a) is 0% by mass, the layer (a) may also be a layer composed solely of the aforementioned polyimide. The content of inorganic filler in the layer (b) is not particularly limited as long as it is higher than that in the layer (a), but is preferably 0.03% by mass or more, more preferably 0.05% by mass or more, even more preferably 0.08% by mass or more, and even more preferably 0.1% by mass or more. The upper limit is not particularly limited, but is preferably 3% by mass or less, more preferably 1% by mass or less, and even more preferably 0.5% by mass or less. By adjusting the content of inorganic fillers in layers (a) and (b) to the above range, high slip properties of the transparent high heat-resistant laminated film surface can be maintained without compromising the transparency of the transparent high heat-resistant laminated film.

[0032] For transparent high heat-resistant laminated films, by adding more inorganic fillers to the side opposite to the side forming the functional element (layer (a) above) (layer (b) above), or by adding inorganic fillers only to layer (b), the smoothness of the surface of layer (a) can be ensured, and a long strip of transparent high heat-resistant laminated film that can be rolled up without wrinkles in the form of a long strip roll can be obtained.

[0033] Examples of inorganic fillers include silica, carbon, and ceramics, with silica being the most preferred. These inorganic fillers can be used alone or in combination of two or more. Adding inorganic fillers imparts protrusions to the surface of the transparent, high-heat-resistant laminate, thereby increasing the surface slippage of the transparent, high-heat-resistant laminate. Furthermore, adding inorganic fillers can also reduce the CTE and Rth of the transparent, high-heat-resistant laminate. The average particle size of the inorganic filler is preferably 1 nm or more, more preferably 5 nm or more, further preferably 10 nm or more, and particularly preferably 30 nm or more. Furthermore, it is preferably 1 μm or less, more preferably 500 nm or less, and even more preferably 100 nm or less.

[0034] The method for adding inorganic fillers to transparent, high-heat-resistant laminated films is not particularly limited. Examples include adding them as powder or in the form of inorganic fillers / solvents (slurry) during or after the preparation of the aforementioned polyamic acid (polyimide precursor) solution, polyimide solution, polyamide-imide solution, or polyamide solution. Among these, the method of adding them as slurry is particularly preferred. As for the slurry, there is no particular limitation. Examples include slurries made by dispersing silica with an average particle size of 10 nm at a concentration of 20% by mass in N,N-dimethylacetamide (DMAC) (e.g., "Snowtex (registered trademark) DMAC-ST" manufactured by Nissan Chemical Industry Co., Ltd.), and slurries made by dispersing silica with an average particle size of 80 nm at a concentration of 20% by mass in N,N-dimethylacetamide (DMAC) (e.g., "Snowtex (registered trademark) DMAC-ST-ZL" manufactured by Nissan Chemical Industry Co., Ltd.).

[0035] The transparent high-heat-resistant laminated film of the present invention can be a two-layer structure consisting only of layer (a) and layer (b) described above, or it can be a laminated structure with three or more layers. Furthermore, it is preferable that all layers (a) and (b) constituting the transparent high-heat-resistant laminated film contain a polyimide composition. It should be noted that, in this specification, the physical properties of the transparent high-heat-resistant laminated film (yellowness index, total transmittance, haze, etc.) refer to the overall values ​​of the transparent high-heat-resistant laminated film unless otherwise specified.

[0036] The yellowness index (hereinafter also referred to as "yellowness index" or "YI") of the transparent high heat-resistant laminated film in this invention is preferably 10 or less, more preferably 7 or less, further preferably 5 or less, and even more preferably 3 or less. There is no particular limitation on the lower limit of the yellowness index of the above-mentioned transparent high heat-resistant laminated film, but for use in flexible electronic devices, it is preferably 0.1 or more, more preferably 0.2 or more, and even more preferably 0.3 or more.

[0037] The transmittance of the transparent high-heat-resistant laminated film at a wavelength of 400 nm in this invention is preferably 70% or more, more preferably 72% or more, further preferably 75% or more, and even more preferably 80% or more. There is no particular upper limit to the transmittance of the aforementioned transparent high-heat-resistant film at a wavelength of 400 nm, but for use in flexible electronic devices, it is preferably 99% or less, more preferably 98% or less, and even more preferably 97% or less.

[0038] The total light transmittance of the transparent high-heat-resistant laminated film in this invention is preferably 75% or more, more preferably 85% or more, further preferably 87% or more, and even more preferably 88% or more. There is no particular upper limit to the total light transmittance of the above-mentioned transparent high-heat-resistant laminated film, but for use in flexible electronic devices, it is preferably 98% or less, more preferably 97% or less.

[0039] The haze of the transparent high heat-resistant laminated film in this invention is preferably 2.0 or less, more preferably 1.5 or less, even more preferably 1.0 or less, even more preferably 0.8 or less, even more preferably 0.5 or less, and even more preferably 0.3 or less.

[0040] The thickness direction phase difference (Rth) of the transparent high heat-resistant laminated film in this invention is preferably less than 500 nm, more preferably less than 300 nm, even more preferably less than 200 nm, and even more preferably less than 100 nm. There is no particular limitation on the lower limit of the Rth of the above-mentioned transparent high heat-resistant laminated film, but for use in flexible electronic devices, it is preferably 0.1 nm or more, more preferably 0.5 nm or more.

[0041] The thickness of the transparent, high-heat-resistant laminated film in this invention is preferably 5 μm or more, more preferably 8 μm or more, even more preferably 15 μm or more, and even more preferably 20 μm or more. There is no particular upper limit to the thickness of the aforementioned transparent, high-heat-resistant laminated film, but for use in flexible electronic devices, it is preferably 200 μm or less, more preferably 150 μm or less, and even more preferably 90 μm or less. If it is too thin, film fabrication and transport may be difficult; if it is too thick, roller transport and other processes may be difficult.

[0042] It should be noted that the colorless and highly transparent polyimide film exhibiting the high coefficient of linear expansion (CTE) of the present invention can be achieved by stretching during the film-forming process of the polyimide film. This stretching operation is achieved by coating a polyimide solution onto a support for making a polyimide film and drying it to form a polyimide film containing 1 to 50% by mass of solvent. Then, while the polyimide film containing 1 to 50% by mass of solvent is being dried at high temperature on or peeled from the support, the stretching is performed by stretching the film by 1.5 to 4.0 times in the MD direction and 1.4 to 3.0 times in the TD direction. In this case, by using an unstretched thermoplastic polymer film as the support for making the polyimide film, and simultaneously stretching both the thermoplastic polymer film and the polyimide film, and then peeling the stretched polyimide film off the thermoplastic polymer film, damage to the polyimide film, especially during stretching in the MD direction, can be prevented, resulting in a higher grade of colorless and highly transparent polyimide film.

[0043] The average coefficient of linear expansion (CTE) of the aforementioned transparent high-heat-resistant laminated film between 30°C and 300°C is preferably 50 ppm / K or less. More preferably, it is 45 ppm / K or less, even more preferably 40 ppm / K or less, even more preferably 30 ppm / K or less, and particularly preferably 20 ppm / K or less. Furthermore, it is preferably -5 ppm / K or more, more preferably -3 ppm / K or more, and even more preferably 1 ppm / K or more. If the CTE is within the above range, the difference between the coefficient of linear expansion and that of a typical support (inorganic substrate) can be kept small, and even when supplied to a heating process, the transparent high-heat-resistant laminated film can be prevented from peeling off from the inorganic substrate or warping together with the support. Here, CTE represents the factor of reversible expansion and contraction with respect to temperature. It should be noted that the CTE of the aforementioned transparent high-heat-resistant laminated film refers to the average value of the CTE in the mechanical direction (MD direction) and the CTE in the width direction (TD direction) of the transparent high-heat-resistant laminated film. The method for measuring the CTE of the aforementioned transparent high-heat-resistant laminated film utilizes the method described in the examples.

[0044] The transparent high heat-resistant laminate of the present invention has a mixed layer at the interface between layers (a) and (b), and the thickness of the mixed layer is 3 μm or more. In the transparent high heat-resistant laminate, if the difference in CTE between each layer is different, it will cause warping. However, if there is a sufficient mixed layer at the interface between layers (a) and (b), warping can be suppressed compared to the case without a mixed layer. The thickness of the mixed layer is preferably 5 μm or more, more preferably 6 μm or more. If the mixed layer is 3 μm or more, the warping of the transparent high heat-resistant laminate can be suppressed to 700 μm or less. The upper limit of the mixed layer is not particularly limited as long as it is less than the sum of the thickness of one layer of layer (a) and the thickness of one layer of layer (b) and does not impair the smoothness of the surface side of layer (a) and the slip properties of the surface side of layer (b). However, it is preferably 90% or less of the sum of the thickness of one layer of layer (a) and the thickness of one layer of layer (b), more preferably 80% or less, and more preferably 70% or less. A mixed layer refers to a transitional layer where the chemical composition of layer (a) and layer (b) varies with a gradient. When the thickness of the mixed layer is not fixed, the value of the thickest (largest) portion represents the mixed layer thickness.

[0045] As a means of forming a mixed layer with a thickness of 3 μm or more, one example is a method of simultaneously or sequentially coating (hereinafter also referred to as "simultaneous / sequential coating") the two layers (a) and (b) described above, allowing the solution to diffuse into each other, and simultaneously forming an integrated film using solution film deposition. In this case, in order to allow the solution to diffuse into each other, it is preferable to perform heating (drying) after a certain time interval following simultaneous / sequential coating. This time is preferably 30 seconds or more, more preferably 60 seconds or more, further preferably 90 seconds or more, and even more preferably 120 seconds or more. On the other hand, if the next layer (second layer) is formed (coated) after heating (drying) the first layer, whether the heating process is in progress or after completion, the number of mixed layers is less than in the case of simultaneous / sequential coating. However, even when heating (drying) is in progress, for example, if the second layer is coated with a solution containing a large amount of solvent and the time is waiting for solvent diffusion, the number of mixed layers is generally less than in the case of simultaneous / sequential coating, but the mixing itself is promoted. Furthermore, even when heating (drying) is halfway through, for example, if solvent is applied to the second layer and its diffusion is promoted, there are more mixed layers compared to simultaneous / sequential coating, but the mixing itself is promoted.

[0046] Furthermore, as a combination of layers (a) and (b) described above, one layer can be a polyamic acid solution, and the other layer can be a polyimide composed of soluble polyimide. Even when both layers (a) and (b) are soluble polyimides, a mixed layer can be generated by simultaneous or sequential coating. However, since the mixed layer becomes thicker when one layer is polyamic acid, it is preferable from the viewpoint of suppressing warping. Moreover, it is more preferable to promote mixing by making both layers (a) and (b) polyimides composed of polyamic acid solution.

[0047] By making films with two or more layers of materials (resins) with different physical properties, films with various properties can also be made. In addition, it is believed that by making any one layer a layer that absorbs ultraviolet or infrared light, it is possible to have the characteristic of spectral dispersion. Furthermore, the incident and outgoing light can be controlled by using layers with different refractive indices.

[0048] The heat shrinkage rate of the above-mentioned transparent high heat-resistant laminated film between 30°C and 500°C is preferably ±0.9%, more preferably ±0.6%. Heat shrinkage rate is a factor that represents the irreversible expansion and contraction with respect to temperature.

[0049] The tensile breaking strength of the aforementioned transparent high-heat-resistant laminated film is preferably 60 MPa or higher, more preferably 120 MPa or higher, and even more preferably 240 MPa or higher. There is no particular upper limit to the tensile breaking strength; in fact, it is approximately less than 1000 MPa. If the tensile breaking strength is 60 MPa or higher, the aforementioned transparent high-heat-resistant laminated film can be prevented from breaking during peeling from the inorganic substrate. It should be noted that the tensile breaking strength of the aforementioned transparent high-heat-resistant laminated film refers to the average of the tensile breaking strength in the mechanical direction (MD direction) and the tensile breaking strength in the width direction (TD direction). The method for determining the tensile breaking strength of the aforementioned transparent high-heat-resistant laminated film utilizes the method described in the examples. It should be noted that when fabricating after coating on a glass substrate using a casting coater, the two orthogonal directions, parallel and perpendicular, are also considered as (MD direction) and (TD direction) respectively during casting coater coating. The same applies to the tensile elongation at break and tensile modulus of elasticity.

[0050] The tensile elongation at break of the aforementioned transparent high-heat-resistant laminated film is preferably 1% or more, more preferably 5% or more, and even more preferably 20% or more. A tensile elongation at break of 1% or more provides excellent workability. It should be noted that the tensile elongation at break of the aforementioned transparent high-heat-resistant laminated film refers to the average of the tensile elongation at break in the mechanical direction (MD direction) and the tensile elongation at break in the width direction (TD direction). The method for determining the tensile elongation at break of the aforementioned transparent high-heat-resistant laminated film utilizes the method described in the examples.

[0051] The tensile modulus of the aforementioned transparent high-heat-resistant laminated film is preferably 2 GPa or higher, more preferably 3 GPa or higher, and even more preferably 4 GPa or higher. If the tensile modulus of elasticity is 3 GPa or higher, the tensile deformation of the aforementioned transparent high-heat-resistant laminated film during peeling from the inorganic substrate is less, resulting in excellent operability. The tensile modulus of elasticity is preferably 20 GPa or lower, more preferably 12 GPa or lower, and even more preferably 10 GPa or lower. If the tensile modulus of elasticity is 20 GPa or lower, the aforementioned transparent high-heat-resistant laminated film can be used as a flexible film. It should be noted that the tensile modulus of elasticity of the aforementioned transparent high-heat-resistant laminated film refers to the average of the tensile modulus of elasticity in the mechanical direction (MD direction) and the tensile modulus of elasticity in the width direction (TD direction) of the transparent high-heat-resistant laminated film layer. The method for determining the tensile modulus of elasticity of the aforementioned transparent high-heat-resistant laminated film utilizes the method described in the examples.

[0052] The thickness non-uniformity of the aforementioned transparent high-heat-resistant laminated film is preferably 20% or less, more preferably 12% or less, even more preferably 7% or less, and particularly preferably 4% or less. If the thickness non-uniformity exceeds 20%, it tends to be difficult to apply to narrow portions. It should be noted that the thickness non-uniformity of the transparent high-heat-resistant laminated film can be measured, for example, by using a contact thickness gauge to randomly select about 10 locations on the film being measured, and the thickness can be obtained based on the following formula. Membrane thickness non-uniformity (%) =100×(maximum film thickness-minimum film thickness)÷average film thickness

[0053] The aforementioned transparent high-heat-resistant laminated film is preferably obtained in its manufacturing process as a long strip of transparent high-heat-resistant laminated film with a width of 300 mm or more and a length of 10 m or more, and is more preferably a roll of transparent high-heat-resistant laminated film wound on a core. When the aforementioned transparent high-heat-resistant laminated film is wound into a roll, it is easy to transport in this form.

[0054] As a means of producing a film with two or more layers, various methods can be considered, such as simultaneous coating using a T-mold that can simultaneously spray out two or more layers, sequential coating by coating one layer after coating the next, drying one layer after coating the next, coating one layer after coating the next, or multilayering based on the addition of a thermoplastic layer by heating lamination, etc. In this invention patent, in order to make the mixed layer 3 μm or more, it is particularly preferred to use simultaneous coating using a T-mold that can simultaneously spray out two or more layers, or sequential coating by coating one layer after coating the next.

[0055] The thickness of layer (a) is preferably 1 μm or more. More preferably, it is 3 μm or more, even more preferably 5 μm or more, and still more preferably 10 μm or more. Furthermore, from the viewpoint of achieving overall thin-film properties of the transparent high-heat-resistant laminate, it is preferably 30 μm or less, and more preferably 28 μm or less. It should be noted that the thickness of layer (a) does not include the thickness of the mixed layer. In addition, when the thickness of layer (a) is not fixed, it is set to the value of the thickest (largest) portion of the mixed layer existing at the interface with layer (a). That is, the thickness of layer (a) is set to the thinnest (smallest) value.

[0056] The thickness of layer (b) is preferably 0.1 μm or more, more preferably 0.4 μm or more. Furthermore, from the viewpoint of achieving overall thin-film properties of the transparent high-heat-resistant laminated film, it is preferably 5 μm or less, more preferably 2 μm or less, and even more preferably 1 μm or less. It should be noted that the thickness of layer (b) does not include the thickness of the mixed layer. Furthermore, when the thickness of layer (b) is not fixed, it is set to the value of the portion where the mixed layer at the interface with layer (b) is thickest. Specifically, the thickness of the portion where the thicknesses of layer (a) and the mixed layer are measured is taken as the thickness of layer (b). That is, the overall thickness of the transparent high-heat-resistant laminated film composed of layers (a) and (b) is the sum of the thicknesses of layer (a), layer (b), and the mixed layer.

[0057] The warpage of the transparent, high-heat-resistant laminate is preferably 700 μm or less, more preferably 600 μm or less. By suppressing the warpage of the transparent, high-heat-resistant laminate to 700 μm or less, stress caused by film warpage can be suppressed when forming a device on the transparent, high-heat-resistant laminate and peeling it from the inorganic substrate. The method for measuring the warpage of the transparent, high-heat-resistant laminate is the method described in the examples.

[0058] <Inorganic substrate> As the aforementioned inorganic substrate, any plate-shaped inorganic substrate that can be used as a substrate formed from inorganic materials is acceptable. Examples include inorganic substrates with glass plates, ceramic plates, semiconductor wafers, metals, etc. as the main body, as well as inorganic substrates obtained by laminating these glass plates, ceramic plates, semiconductor wafers, and metals as composites, inorganic substrates in which these materials are dispersed, and inorganic substrates containing these materials and fibers.

[0059] The aforementioned glass plates include quartz glass, high silicate glass (96% silica), soda lime glass, lead glass, aluminoborosilicate glass, borosilicate glass (Pyrex, a registered trademark), alkali-free borosilicate glass, microsheet borosilicate glass, and aluminosilicate glass. Among these, glass plates with a coefficient of linear expansion of 5 ppm / K or less are preferred. In the case of commercially available products, Corning Gorilla Glass Co., Ltd.'s "Corning 7059" and "Corning 1737", "EAGLE", Asahi Glass Co., Ltd.'s "AN100", Nippon Electric Glass Co., Ltd.'s "OA10" and "OA11G", and SCHOTT Co., Ltd.'s "AF32" are preferred as liquid crystal glass.

[0060] The semiconductor wafers mentioned above are not particularly limited and can include silicon wafers, germanium wafers, silicon-germanium wafers, gallium-arsenic wafers, aluminum-gallium-indium wafers, nitrogen-phosphorus-arsenic-antimony wafers, SiC, InP (indium phosphide), InGaAs, GaInNAs, LT, LN, ZnO (zinc oxide), CdTe (cadmium telluride), ZnSe (zinc selenide), etc. Among them, silicon wafers are preferred, and mirror-polished silicon wafers with a size of 8 inches or larger are particularly preferred.

[0061] The aforementioned metals include single-element metals such as W, Mo, Pt, Fe, Ni, and Au; alloys such as Inconel, Monel, Nimonic, carbon-copper, Fe-Ni-based Invar alloy, and super Invar alloy. Furthermore, multilayer metal sheets formed by adding other metal layers or ceramic layers to these metals are also included. In this case, when the overall coefficient of linear expansion (CTE) with the added layers is low, Cu, Al, etc., can also be used as the main metal layer. There are no limitations on the metals used as added metal layers, as long as they enhance the adhesion to the high-heat-resistant film and possess properties such as non-diffusion, chemical resistance, and good heat resistance; however, suitable examples include Cr, Ni, TiN, and Mo-containing Cu.

[0062] The ceramic plate used in this invention includes Al2O3, Mullite, AlN, SiC, crystallized glass, etc. Ceramic substrates including cordierite, spodumene, Pb-BSG+CaZrO3+Al2O3, crystallized glass+Al2O3, crystallized calcium (Ca)-BSG, BSG+quartz, BSG+quartz, BSG+Al2O3, Pb-BSG+Al2O3, glass-ceramic, and zerodur.

[0063] The planar portion of the aforementioned inorganic substrate is preferably sufficiently flat. Specifically, the PV value of the surface roughness is 50 nm or less, more preferably 20 nm or less, and even more preferably 5 nm or less. If it is rougher, the peel strength between the transparent high-heat-resistant laminate and the inorganic substrate may sometimes be insufficient. The thickness of the aforementioned inorganic substrate is not particularly limited, but from an operability point of view, a thickness of 10 mm or less is preferred, more preferably 3 mm or less, and even more preferably 1.3 mm or less. Regarding the lower limit of the thickness, there is no particular limitation, but 0.07 mm or more is preferred, more preferably 0.15 mm or more, and even more preferably 0.3 mm or more. If it is too thin, it is easily damaged, making operation difficult. Furthermore, if it is too thick, it becomes heavy, making operation difficult.

[0064] <Layered Body> The laminate of the present invention is a laminate formed by stacking the aforementioned transparent high-heat-resistant laminate and the aforementioned inorganic substrate without substantially using adhesives. Since a smooth surface is required during device formation, the lamination surface with the inorganic substrate is preferably layer (b). Furthermore, in the thickness direction of the laminate, it can be a structure with inorganic substrates at both ends (e.g., inorganic substrate / transparent high-heat-resistant laminate / inorganic substrate). In this case, the transparent high-heat-resistant laminate at both ends and the inorganic substrate are substantially bonded without adhesives.

[0065] The shape of the laminate is not particularly limited; it can be square or rectangular. A rectangle is preferred, with the longest side preferably 300 mm or more, more preferably 500 mm or more, and even more preferably 1000 mm or more. There is no particular upper limit, but a substrate used in industry that allows for changes in size and material is preferred. 20,000 mm or less is sufficient, but 10,000 mm or less is also acceptable.

[0066] <Adhesive> In this invention, there is substantially no adhesive layer between the inorganic substrate and the transparent high-heat-resistant laminate. Here, the adhesive layer referred to in this invention means a layer in which the Si (silicon element) content is less than 10% (less than 10% by mass). Furthermore, the fact that the adhesive layer between the inorganic substrate and the transparent high-heat-resistant laminate is substantially not used (not present) means that its thickness is preferably 0.4 μm or less, more preferably 0.1 μm or less, further preferably 0.05 μm or less, particularly preferably 0.03 μm or less, and most preferably 0 μm.

[0067] <Silane Coupling Agent (SCA)> In the laminate, a silane coupling agent layer is preferably present between the transparent, high-heat-resistant laminate and the inorganic substrate. In this invention, the silane coupling agent refers to a compound containing 10% by mass or more of Si (silicon element). Furthermore, it is preferable that the structure contains alkoxy groups. Additionally, it is preferable that it does not contain methyl groups. By using the silane coupling agent layer, the intermediate layer between the transparent, high-heat-resistant laminate and the inorganic substrate can be thinned, thus producing the following effects: less degassing during heating, less leaching even in wet processes, and even if leaching occurs, it is limited to trace amounts. The silane coupling agent preferably contains a large amount of silicon oxide to improve heat resistance, and particularly preferably a silane coupling agent with heat resistance at around 400°C. The thickness of the silane coupling agent layer is preferably less than 0.2 μm. As a range suitable for use in flexible electronic devices, it is preferably 100 nm or less (0.1 μm or less), more preferably 50 nm or less, and even more preferably 10 nm. Typically, it is around 0.10 μm or less during fabrication. Furthermore, in processes where minimal silane coupling agent is desired, it can be used at a wavelength of 5 nm or less. However, at wavelengths below 1 nm, there is a possibility of decreased peel strength or the appearance of partially unattached areas; therefore, a wavelength of 1 nm or more is preferred.

[0068] The silane coupling agent in this invention is not particularly limited, but preferably has an amino or epoxy group. Specific examples of silane coupling agents include N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N-(1,3-dimethyl-butylene)propylamine, 2-(3,4- 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-epoxypropoxypropyltrimethoxysilane, 3-epoxypropoxypropylmethyldiethoxysilane, 3-epoxypropoxypropyltriethoxysilane, vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-epoxypropoxypropyltrimethoxysilane, 3-epoxypropoxypropylmethyldiethoxysilane 3-Epoxypropoxypropyltriethoxysilane, p-Styryltrimethoxysilane, 3-Methacryloxypropylmethyldimethoxysilane, 3-Methacryloxypropyltrimethoxysilane, 3-Methacryloxypropylmethyldiethoxysilane, 3-Methacryloxypropyltriethoxysilane, 3-Acryloyloxypropyltrimethoxysilane, N-Phenyl-3-aminopropyltrimethoxysilane, N-(Vinylbenzyl)-2-amino 3-aminopropyltrimethoxysilane hydrochloride, 3-ureopropyltriethoxysilane, 3-chloropropyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, bis(triethoxysilylpropyl)tetrasulfide, 3-isocyanatopropyltriethoxysilane, tris(3-trimethoxysilylpropyl)isocyanurate, chloromethylphenylethyltrimethoxysilane, chloromethyltrimethoxysilane, etc. Preferred examples include N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N-(1,3-dimethyl-butylene)propylamine, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-epoxypropoxypropyltrimethoxysilane, 3-epoxypropoxypropylmethyldiethoxysilane, 3-epoxypropoxypropyltriethoxysilane, aminophenyltrimethoxysilane, aminophenylethyltrimethoxysilane, and aminophenylaminomethylphenylethyltrimethoxysilane. When heat resistance is required in the process, it is preferable to link Si and the amino group via an aromatic linkage.

[0069] The peel strength between the transparent, high-heat-resistant laminate and the inorganic substrate after heating to 300°C is preferably 0.3 N / cm or less. Therefore, after a device is formed on the transparent, high-heat-resistant laminate, peeling between the laminate and the inorganic substrate becomes very easy. This allows for the manufacture of mass-producible device connectors, facilitating the manufacture of flexible electronic devices. The peel strength is preferably 0.25 N / cm or less, more preferably 0.2 N / cm or less, even more preferably 0.15 N / cm or less, and particularly preferably 0.12 N / cm or less. Furthermore, it is preferably 0.03 N / cm or more. From the perspective of preventing the laminate from peeling when a device is formed on the transparent, high-heat-resistant laminate, it is more preferably 0.06 N / cm or more, even more preferably 0.08 N / cm or more, and particularly preferably 0.1 N / cm or more. The peel strength mentioned above refers to the peel strength between the transparent high heat-resistant laminate and the inorganic substrate in the laminate after the transparent high heat-resistant laminate is bonded to the inorganic substrate and then heat-treated at 300°C for 1 hour in a nitrogen atmosphere.

[0070] The laminate of the present invention can be manufactured, for example, by the following steps. At least one side of the inorganic substrate can be treated with a silane coupling agent, and the silane-coupling agent-treated side can be overlapped with a transparent high-heat-resistant film. The two are then laminated under pressure to obtain a laminate. Alternatively, at least one side of the transparent high-heat-resistant laminate can be treated with a silane coupling agent, and the silane-coupling agent-treated side can be overlapped with the inorganic substrate. The two are then laminated under pressure to obtain a laminate. Furthermore, it is preferable to overlap the surface of layer (b) of the transparent high-heat-resistant laminate with the inorganic substrate. As a method of applying pressure, examples include ordinary atmospheric pressing or lamination, or pressing or lamination in a vacuum. To obtain stable peel strength across the entire surface, atmospheric lamination is preferred for large-sized laminates (e.g., exceeding 200 mm). Conversely, for small-sized laminates of approximately 200 mm or less, vacuum pressing is preferred. A vacuum level obtained with a conventional oil rotary pump is sufficient, approximately 10 Torr or less is adequate. The preferred pressure is 1 MPa to 20 MPa, more preferably 3 MPa to 10 MPa. At high pressures, the substrate may break; at low pressures, gaps may sometimes appear. The preferred temperature is 90°C to 300°C, more preferably 100°C to 250°C. High temperatures may sometimes damage the membrane; low temperatures may sometimes weaken the adhesion.

[0071] Fabrication of films with integrated electronic components (flexible electronic devices) If the above-described laminate is used, flexible electronic devices can be easily fabricated using existing equipment and processes for electronic device manufacturing. Specifically, flexible electronic devices can be fabricated by forming electronic devices on a transparent, high-heat-resistant laminate film of the laminate and then peeling the transparent, high-heat-resistant laminate film off the laminate together. In this application specification, electronic devices refer to: wiring substrates with single-sided, double-sided, or multi-layer structures that carry electrical wiring; electronic circuits including active components such as transistors and diodes or passive components such as resistors, capacitors, and inductors; sensor elements that sense pressure, temperature, light, humidity, etc.; biosensor elements; light-emitting elements; image display elements such as liquid crystal displays, electrophoretic displays, and self-emissive displays; wireless or wired communication elements; computing elements; storage elements; MEMS elements; solar cells; thin-film transistors, etc.

[0072] Furthermore, the wiring substrate also includes an interposer layer that functions as an electrode for penetrating the polyimide. By making it approximately penetrating, the process of fabricating the through-hole after peeling off the inorganic substrate can be significantly reduced. Known methods can be used to fabricate the through-hole. For example, in approximately penetrating, a UV nanolaser is used to penetrate the through-hole. Then, for example, using conventional methods for through-holes in double-sided printed wiring boards or vias in multilayer printed wiring boards, the through-hole is filled with conductive metal, and wiring patterns are formed using the metal as needed. In approximately penetrating, the through-hole can also be opened as described above and then bonded to the inorganic substrate. Alternatively, the through-hole can be fabricated by bonding the inorganic substrate to a transparent high-heat-resistant laminate. Metallization can be performed by penetrating the transparent high-heat-resistant laminate, or by opening a hole on one side of the transparent high-heat-resistant laminate without penetrating the opposite surface.

[0073] In the method for manufacturing flexible electronic devices described in this application, after forming the device on a transparent, high-heat-resistant laminate film of a laminate produced by the above method, the transparent, high-heat-resistant laminate film is peeled off from the inorganic substrate.

[0074] <Peeling of a transparent, high-heat-resistant laminate with integrated devices from an inorganic substrate> There are no particular limitations on the method for peeling a transparent, heat-resistant laminated film with a device attached from an inorganic substrate. Methods include: peeling from the end with tweezers; forming a slit in the transparent, heat-resistant laminated film, applying adhesive tape to one edge of the slit, and then winding it up from that tape portion; and vacuum-adhesive cleaning of one edge of the slit portion of the transparent, heat-resistant laminated film and then winding it up from that portion. It should be noted that if a small bend occurs in the slit portion of the transparent, heat-resistant laminated film during peeling, stress will be applied to the device in that area, posing a risk of damage. Therefore, peeling with a large curvature is preferred. For example, it is preferable to peel while winding it onto a roller with a large curvature, or to use a machine with a structure where a roller with a large curvature is located at the peeling portion. Methods for forming cuts in the aforementioned transparent high-heat-resistant laminated film include cutting the transparent high-heat-resistant laminated film using a cutting tool such as a blade, cutting the transparent high-heat-resistant laminated film by scanning the laminated film relative to each other with a laser, cutting the transparent high-heat-resistant laminated film by scanning the laminated film relative to each other with a water jet, and cutting the transparent high-heat-resistant laminated film simultaneously with a semiconductor chip cutting device up to several glass layers. However, there are no particular limitations on the method. For example, when using the above methods, it is also possible to appropriately employ techniques such as superimposing ultrasonic waves on the cutting tool, or adding reciprocating motion, up-and-down motion, etc., to improve cutting performance. In addition, it is also useful to pre-attach other reinforcing substrates to the part to be peeled off, and then peel off the reinforcing substrates together. When the flexible electronic device to be peeled off is the back plane of a display device, the front plane of the display device can be pre-attached, and after integration on an inorganic substrate, the two can be peeled off simultaneously to obtain a flexible display device. Example

[0075] The present invention will be described in detail below using examples, but the present invention is not limited to the following examples as long as it does not deviate from its spirit.

[0076] [Manufacturing Example 1 (Manufacturing of Polyimide Solution 1 (PI-1))] In a reaction vessel equipped with a nitrogen inlet tube, a Dean-Stark tube and reflux tube, a thermometer, and a stir bar, nitrogen gas was introduced while 19.86 parts by mass of 4,4'-diaminodiphenyl sulfone (4,4'-DDS), 4.97 parts by mass of 3,3'-diaminodiphenyl sulfone (3,3'-DDS), and 80 parts by mass of N,N-dimethylacetamide (DMAc) were added. Next, at room temperature, 31.02 parts by mass of 4,4'-oxyphthalic dianhydride (ODPA), 24 parts by mass of GBL, and 13 parts by mass of toluene were added. The mixture was then heated to an internal temperature of 160°C and refluxed at 160°C for 1 hour to carry out imidization. After imidization, the temperature was raised to 180°C, and the reaction continued while toluene was removed. After reacting for 12 hours, the oil bath was removed and the room temperature was restored. DMAc was added to make the solid component a concentration of 20% by mass, resulting in a polyimide solution 1 with a specific viscosity of 0.70 dl / g.

[0077] [Manufacturing Example 2 (Manufacturing of Polyamic Acid Solution 1 (PAA-1))] After purging the reaction vessel equipped with a nitrogen inlet pipe, reflux pipe, and stir bar with nitrogen, 33.36 parts by weight of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (TFMB), 336.31 parts by weight of N-methyl-2-pyrrolidone (NMP), and a dispersion (Nissan Chemical Industries, Ltd. "SNOWTEX (registered trademark) DMAC-ST-ZL") made by dispersing colloidal silica in dimethylacetamide as a lubricant were added and allowed to settle completely. The solution was completely dissolved so that the silica (lubricant) accounted for 0.3% by mass of the total polymer solids in the polyamic acid solution. Then, 9.81 parts by mass of 1,2,3,4-cyclobutanetetracarboxylic dianhydride (CBDA), 11.34 parts by mass of 3,3',4,4'-biphenyltetracarboxylic acid (BPDA), and 4.85 parts by mass of 4,4'-oxyphthalic dianhydride (ODPA) were added in batches as solids, and the mixture was stirred at room temperature for 24 hours. A polyamic acid solution 1 with a solid content of 15% by mass and a specific viscosity of 3.50 dl / g was obtained (molar ratio of TFMB / / CBDA / BPDA / ODPA = 1.000 / / 0.480 / 0.370 / 0.150).

[0078] [Manufacturing Example 3 (Manufacturing of Polyamic Acid Solution 2 (PAA-2))] After purging the reaction vessel equipped with a nitrogen inlet pipe, reflux pipe, and stir bar with nitrogen, 336.31 parts by mass of N-methyl-2-pyrrolidone (NMP) were added to 33.36 parts by mass of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (TFMB) and allowed to dissolve completely. Then, 9.81 parts by mass of 1,2,3,4-cyclobutanetetracarboxylic dianhydride (CBDA), 11.34 parts by mass of 3,3',4,4'-biphenyltetracarboxylic acid (BPDA), and 4.85 parts by mass of 4,4'-oxydiphthalic dianhydride (ODPA) were added in batches in solid form, and the mixture was stirred at room temperature for 24 hours. Then, a polyamic acid solution 2 with a solid content of 15% by mass and a specific viscosity of 3.50 dl / g was obtained (molar ratio of TFMB / / CBDA / BPDA / ODPA = 1.000 / / 0.480 / 0.370 / 0.150).

[0079] [Manufacturing Example 4 (Manufacturing of Polyamic Acid Solution 3 (PAA-3))] After purging the reaction vessel equipped with a nitrogen inlet pipe, reflux pipe, and stir bar with nitrogen, 22.0 parts by weight of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (TFMB), 252.1 parts by weight of N,N-dimethylacetamide (DMAc), and a dispersion (SNOWTEX DMAC-ST-ZL, a registered trademark manufactured by Nissan Chemical Industries, Ltd.) as a lubricant, were added and completely dissolved so that the total amount of silica (lubricant) relative to the total amount of polymer solids in the polyamic acid solution was 0.3% by weight. Then, 22.0 parts by weight of 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) were added in batches in solid form, and the mixture was stirred at room temperature for 24 hours. Then, 165.7 parts by mass of DMAc were added for dilution to obtain a polyamic acid solution 3 with a solid content (NV) of 11% by mass and a specific viscosity of 3.50 dl / g (molar ratio of TFMB / BPDA = 0.920 / 1.000).

[0080] [Manufacturing Example 5 (Manufacturing of Polyamic Acid Solution 4 (PAA-4))] After purging the reaction vessel equipped with a nitrogen inlet pipe, reflux pipe, and stir bar with nitrogen, 252.1 parts by mass of N,N-dimethylacetamide (DMAc) were added to 22.0 parts by mass of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (TFMB) and completely dissolved. Then, 22.0 parts by mass of 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) were added in batches as a solid, and the mixture was stirred at room temperature for 24 hours. Finally, 165.7 parts by mass of DMAc were added for dilution, yielding a polyamic acid solution 4 with a solid content (NV) of 11% by mass and a specific viscosity of 3.50 dl / g (TFMB / BPDA molar ratio = 0.920 / 1.000).

[0081] [Manufacturing Example 6 (Manufacturing of Polyamic Acid Solution 5 (PAA-5))] After purging the reaction vessel equipped with a nitrogen inlet pipe, reflux pipe, and stir bar with nitrogen, 22.73 parts by mass of 4,4'-diaminobenzoylaniline (DABAN), 201.1 parts by mass of N,N-dimethylacetamide (DMAc), and a dispersion (SNOWTEX DMAC-ST-ZL, a registered trademark of Nissan Chemical Industries, Ltd.) as a lubricant, which is formed by dispersing colloidal silica in dimethylacetamide, were added and completely dissolved so that the silica (lubricant) was 0.5% by mass relative to the total amount of polymer solids in the polyamic acid solution. Then, 19.32 parts by mass of 1,2,3,4-cyclobutanetetracarboxylic dianhydride (CBDA) were added in batches in solid form, and the mixture was stirred at room temperature for 24 hours. Then, 173.1 parts by mass of DMAc were added for dilution to obtain a polyamic acid solution 5 with an NV (solid content) of 10% by mass and a specific viscosity of 3.10 dl / g (molar ratio of DABAN / CBDA = 1.000 / 0.985).

[0082] [Manufacturing Example 7 (Manufacturing of Polyamic Acid Solution 6 (PAA-6))] After purging the reaction vessel equipped with a nitrogen inlet pipe, reflux pipe, and stir bar with nitrogen, 201.1 parts by mass of N,N-dimethylacetamide (DMAc) were added to 22.73 parts by mass of 4,4'-diaminobenzoylaniline (DABAN) and completely dissolved. Then, 19.32 parts by mass of 1,2,3,4-cyclobutanetetracarboxylic dianhydride (CBDA) were added in batches as a solid, and the mixture was stirred at room temperature for 24 hours. Finally, 173.1 parts by mass of DMAc were added for dilution to obtain a polyamic acid solution 6 with an NV (solid content) of 10% by mass and a specific viscosity of 3.10 dl / g (DABAN / CBDA molar ratio = 1.000 / 0.985).

[0083] [Manufacturing Example 8 (Manufacturing of Polyamic Acid Solution 7 (PAA-7))] A bilayer silsesquioxane derivative (AASQ1) containing an anhydride group was obtained from Nippon Materials Technology Co., Ltd. [Chemical Formula 1] Next, after purging the reaction vessel equipped with a nitrogen inlet pipe, reflux pipe, and stirring rod with nitrogen, 490.2 parts by mass of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (TFMB), 5340 parts by mass of N-methyl-2-pyrrolidone (NMP), and a dispersion (SNOWTEX DMAC-ST-ZL, a registered trademark of Nissan Chemical Industries, Ltd.) as a lubricant, were added and completely dissolved so that the total amount of silica (lubricant) relative to the total amount of polymer solids in the polyamic acid solution was 0.3% by mass. Then, 327.2 parts by mass of pyromellitic dianhydride (PMDA) and 45.4 parts by mass of AASQ1 were added in batches in solid form, and the mixture was stirred at room temperature for 24 hours. Then, a polyamic acid solution 7 with a solid content of 14% by mass and a specific viscosity of 1.46 dl / g was obtained (molar ratio of TFMB / / PMDA / AASQ1 = 1.000 / / 0.980 / 0.020).

[0084] [Manufacturing Example 9 (Manufacturing of Polyamic Acid Solution 8 (PAA-8))] After purging the reaction vessel equipped with a nitrogen inlet pipe, reflux pipe, and stir bar with nitrogen, 490.2 parts by mass of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (TFMB) and 5340 parts by mass of N-methyl-2-pyrrolidone (NMP) were added and completely dissolved. Then, 327.2 parts by mass of pyromellitic dianhydride (PMDA) and 45.4 parts by mass of AASQ1 were added in batches as solids, and the mixture was stirred at room temperature for 24 hours. A polyamic acid solution 8 with a solid content of 14% by mass and a specific viscosity of 1.46 dl / g was obtained (molar ratio of TFMB / / PMDA / AASQ1 = 1.000 / / 0.980 / 0.020).

[0085] [Manufacturing Example 10 (Manufacturing of Polyamic Acid Solution 9 (PAA-9))] The amino-containing bilayer silsesquioxane derivative (AMSQ1) represented by the structure of formula (2) is manufactured by the method described in Japanese Patent Application Publication No. 2006-265243. [Chemical Formula 2] Next, after purging the reaction vessel equipped with a nitrogen inlet pipe, reflux pipe, and stirring rod with nitrogen, 470.8 parts by mass of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (TFMB), 39.9 parts by mass of AMSQ1, 6880 parts by mass of N-methyl-2-pyrrolidone (NMP), and a dispersion (SNOWTEX DMAC-ST-ZL, manufactured by Nissan Chemical Industries, Ltd.) as a lubricant, which is a colloidal silica dispersed in dimethylacetamide, were added and completely dissolved so that the silica (lubricant) relative to the total amount of polymer solids in the polyamic acid solution was 0.3% by mass. Then, 325.6 parts by mass of pyromellitic dianhydride (PMDA) was added in batches in solid form, and the mixture was stirred at room temperature for 24 hours. Then, a polyamic acid solution 7 with a solid content of 11% by mass and a specific viscosity of 3.50 dl / g was obtained (molar ratio of TFMB / AMSQ1 / / PMDA = 0.980 / 0.020 / / 1.000).

[0086] [Manufacturing Example 11 (Manufacturing of Polyamic Acid Solution 10 (PAA-10))] After purging the reaction vessel, which is equipped with a nitrogen inlet pipe, a reflux pipe, and a stir bar, 470.8 parts by mass of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (TFMB), 39.9 parts by mass of AMSQ1, and 6880 parts by mass of N-methyl-2-pyrrolidone (NMP) were added and completely dissolved. Then, 325.6 parts by mass of pyromellitic dianhydride (PMDA) was added in batches in solid form, and the mixture was stirred at room temperature for 24 hours. A polyamic acid solution 7 with a solid content of 11% by mass and a specific viscosity of 3.50 dl / g was obtained (molar ratio of TFMB / AMSQ1 / / PMDA = 0.980 / 0.020 / / 1.000).

[0087] [Manufacturing Example 12 (Manufacturing of Polyamic Acid Solution 11 (PAA-11))] After purging the reaction vessel equipped with a nitrogen inlet pipe, reflux pipe, and stir bar with nitrogen, 470.8 parts by mass of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (TFMB), 6766 parts by mass of N-methyl-2-pyrrolidone (NMP), and a dispersion (SNOWTEX DMAC-ST-ZL, a registered trademark of Nissan Chemical Industries, Ltd.) as a lubricant, which is formed by dispersing colloidal silica in dimethylacetamide, were added and completely dissolved so that the silica (lubricant) relative to the total amount of polymer solids in the polyamic acid solution was 0.3% by mass. Then, 192.4 parts by mass of pyromellitic dianhydride (PMDA) and 173.0 parts by mass of 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) were added in batches in solid form, and the mixture was stirred at room temperature for 24 hours. Then, a polyamic acid solution 11 with a solid content of 11% by mass and a specific viscosity of 3.50 dl / g was obtained (molar ratio of TFMB / / PMDA / BPDA = 1.000 / / 0.600 / 0.400).

[0088] [Manufacturing Example 13 (Manufacturing of Polyamic Acid Solution 12 (PAA-12))] After purging the reaction vessel equipped with a nitrogen inlet pipe, reflux pipe, and stir bar with nitrogen, 470.8 parts by mass of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (TFMB), 39.9 parts by mass of AMSQ1, and 6766 parts by mass of N-methyl-2-pyrrolidone (NMP) were added and completely dissolved. Then, 192.4 parts by mass of pyromellitic dianhydride (PMDA) and 173.0 parts by mass of 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) were added in batches in solid form, and the mixture was stirred at room temperature for 24 hours. A polyamic acid solution 12 with a solid content of 11% by mass and a specific viscosity of 3.50 dl / g was obtained (molar ratio of TFMB / / PMDA / BPDA = 1.000 / / 0.600 / 0.400).

[0089] [Example 1] (Preparation of polyimide film A1) Using a comma coating machine, polyamic acid solution 1 (PAA-1) obtained in Manufacturing Example 2 was coated onto the unlubricated surface of a polyethylene terephthalate film A4100 (manufactured by Toyobo Co., Ltd.) to achieve a final film thickness of 1.5 μm. Then, polyamic acid solution 2 (PAA-2) obtained in Manufacturing Example 3 was coated onto polyamic acid solution 1 (PAA-1) using a die-coating machine to achieve a final film thickness of 22 μm. After 60 seconds, the film was transferred to a hot air oven and dried at 110°C for 10 minutes. The dried, self-supporting polyamic acid film was peeled off from the A4100 film, which served as the support, and passed through a needle tenter frame equipped with needle plates. The ends of the film were held by inserting needles, and the needle plate spacing was adjusted to prevent the film from breaking or causing unnecessary slack. The film was heated at 200°C for 3 minutes, 250°C for 3 minutes, 300°C for 3 minutes, and 400°C for 3 minutes to carry out an imidization reaction. Then, it was cooled to room temperature for 2 minutes, and the poorly planar portions at both ends of the film were cut off using a slitter. The film was then wound into a roll to obtain a 500m long polyimide film A1 with a width of 450mm.

[0090] [Example 2] (Preparation of polyimide film A2) Using a comma coating machine, polyamic acid solution 1 (PAA-1) obtained in Manufacturing Example 2 was coated onto the unlubricated surface of a polyethylene terephthalate film A4100 (manufactured by Toyobo Co., Ltd.) to achieve a final film thickness of 1.5 μm. Next, polyimide solution 1 (PI-1) obtained in Manufacturing Example 1 was coated onto polyamic acid solution 1 (PAA-1) using a die-coating machine to achieve a final film thickness of 22 μm. After 60 seconds, the film was transferred to a hot air oven and dried at 110°C for 10 minutes. The dried, self-supporting polyamic acid / polyimide film was peeled off from the A4100 film, which served as the support. The film was then passed through a needle-type tenter frame equipped with needle plates, where the ends of the film were held by needles. The needle plate spacing was adjusted to prevent the film from breaking or causing unnecessary slack. The film was heated at 200°C for 3 minutes, 250°C for 3 minutes, and 300°C for 6 minutes to induce an imidization reaction. After cooling to room temperature for 2 minutes, the poorly planar portions at both ends of the film were cut off using a slitting machine, and the film was wound into a roll to obtain a 500m long polyimide film A2 with a width of 450mm.

[0091] [Example 3] (Preparation of polyimide film A3) Using a comma coating machine, polyamic acid solution 5 (PAA-5) obtained in Manufacturing Example 6 was coated onto the unlubricated surface of a polyethylene terephthalate film A4100 (manufactured by Toyobo Co., Ltd.) to achieve a final film thickness of 1.5 μm. Next, polyimide solution 1 (PI-1) obtained in Manufacturing Example 1 was coated onto polyamic acid solution 5 (PAA-5) using a die-coating machine to achieve a final film thickness of 22 μm. After 60 seconds, the film was transferred to a hot air oven and dried at 110°C for 10 minutes. The dried, self-supporting polyamic acid / polyimide film was peeled off from the A4100 film, which served as the support. The film was then passed through a needle-type tenter frame equipped with needle plates, where the ends of the film were held by needles. The needle plate spacing was adjusted to prevent the film from breaking or causing unnecessary slack. The film was heated at 200°C for 3 minutes, 250°C for 3 minutes, 300°C for 3 minutes, and 375°C for 3 minutes to induce an imidization reaction. Afterward, the film was cooled to room temperature for 2 minutes, and the poorly planar portions at both ends were cut off using a slitting machine. The film was then wound into a roll to obtain a 500m long polyimide film A3 with a width of 450mm.

[0092] [Example 4] (Preparation of polyimide film A4) The polyimide solution 1 (PI-1) was replaced with polyamic acid solution 2 (PAA-2), and otherwise, the polyimide film A4 was obtained in the same manner as in Example 3.

[0093] [Example 5] (Preparation of polyimide film A5) The polyamic acid solution 1 (PAA-1) was changed to polyamic acid solution 5 (PAA-5), and the polyimide solution 1 (PI-1) was changed to polyamic acid solution 4 (PAA-4). Otherwise, the polyimide film A5 was obtained in the same manner as in Example 2.

[0094] [Example 6] (Preparation of polyimide film A6) The polyamic acid solution 1 (PAA-1) was changed to polyamic acid solution 3 (PAA-3), and the polyimide solution 1 (PI-1) was changed to polyamic acid solution 4 (PAA-4). Otherwise, the polyimide film A6 was obtained in the same manner as in Example 2.

[0095] [Example 7] (Preparation of polyimide film A7) The polyamic acid solution 5 (PAA-5) was changed to polyamic acid solution 7 (PAA-7), and the polyimide solution 1 (PI-1) was changed to polyamic acid solution 8 (PAA-8). Otherwise, the polyimide film A7 was obtained in the same manner as in Example 3.

[0096] [Example 8] (Preparation of polyimide film A8) Polyamic acid solution 1 (PAA-1) was changed to polyamic acid solution 9 (PAA-9), and polyamic acid solution 2 (PAA-2) was changed to polyamic acid solution 10 (PAA-10). Otherwise, polyimide film A8 was obtained in the same manner as in Example 1.

[0097] [Example 9] (Preparation of polyimide film A14) The polyamic acid solution 1 (PAA-1) was changed to polyamic acid solution 11 (PAA-11), the polyamic acid solution 2 (PAA-2) was changed to polyamic acid solution 12 (PAA-12), and the heating conditions were changed to 15 minutes at 200°C, 15 minutes at 250°C, 15 minutes at 300°C, and 15 minutes at 400°C. Otherwise, the polyimide film A14 was obtained in the same manner as in Example 1.

[0098] [Comparative Example 1] (Preparation of polyimide film A9) Using a comma coater, polyamic acid solution 6 (PAA-6) obtained in Manufacturing Example 7 was coated onto the unlubricated surface of a polyethylene terephthalate film A4100 (manufactured by Toyobo Co., Ltd.) to achieve a final film thickness of 3 μm. The polyethylene terephthalate film A4100 was passed through a hot air furnace, wound, and dried at 100°C for 10 minutes. After being wound, it was repositioned on one side of the comma coater, and polyamic acid solution 2 (PAA-2) obtained in Manufacturing Example 3 was coated onto the dried polyamic acid solution 6 (PAA-6) to achieve a final film thickness of 20 μm. It was then dried at 100°C for 10 minutes. The dried, self-supporting polyamic acid film was peeled from the support and passed through a needle-type tenter frame equipped with needle plates. The ends of the film were held by inserting needles, and the needle plate spacing was adjusted to prevent the film from breaking or causing unnecessary slack. The film was then heated at 200°C for 3 minutes, 250°C for 3 minutes, 300°C for 3 minutes, and 370°C for 3 minutes to carry out an imidization reaction. Afterward, it was cooled to room temperature for 2 minutes, and the poorly flat portions at both ends of the film were cut off using a slitting machine. The film was then wound into a roll to obtain a 30m long polyimide film A9 with a width of 450mm. Although a film was obtained, wrinkles were formed during winding.

[0099] [Comparative Example 2] (Preparation of polyimide film A10) Using a comma coater, the polyamic acid solution 6 (PAA-6) obtained in Manufacturing Example 7 was coated onto the unlubricated surface of a polyethylene terephthalate film A4100 (manufactured by Toyobo Co., Ltd.) to achieve a final film thickness of 3 μm. The polyethylene terephthalate film A4100 was passed through a hot air furnace, wound, and dried at 100°C for 10 minutes. After being wound, it was repositioned on one side of the comma coater, and the polyimide solution 1 (PI-1) obtained in Manufacturing Example 1 was coated onto the dried polyamic acid solution 6 (PAA-6) to achieve a final film thickness of 20 μm. It was then dried at 100°C for 10 minutes. The dried, self-supporting polyamic acid / polyimide film was peeled from the support and passed through a needle-type tenter frame equipped with needle plates. The ends of the film were held by inserting needles, and the needle plate spacing was adjusted to prevent the film from breaking or causing unnecessary slack. The film was heated at 200°C for 3 minutes, 250°C for 3 minutes, and 300°C for 6 minutes to carry out an imidization reaction. Then, it was cooled to room temperature for 2 minutes, and the poorly planar portions at both ends of the film were cut off using a slitting machine. The film was then wound into a roll to obtain a 20m long polyimide film A10 with a width of 450mm. Although a film was obtained, wrinkles were formed during winding.

[0100] [Comparative Example 3] (Preparation of polyimide film A11) Using polyamic acid solution 5 (PAA-5) instead of polyamic acid solution 6 (PAA-6), a 300 μm polyimide film A11 was obtained in the same manner as in Comparative Example 1.

[0101] [Comparative Example 4] (Preparation of polyimide film A12) Using a comma coater, polyamic acid solution 3 (PAA-3) obtained in Manufacturing Example 4 was coated onto the unlubricated surface of a polyethylene terephthalate film A4100 (manufactured by Toyobo Co., Ltd.) to achieve a final film thickness of 1.5 μm. The polyethylene terephthalate film A4100 was passed through a hot air furnace, wound, and dried at 100°C for 10 minutes. After winding, it was repositioned on one side of the comma coater, and polyamic acid solution 1 (PAA-1) obtained in Manufacturing Example 3 was coated onto the dried polyamic acid solution 3 (PAA-3) to achieve a final film thickness of 20 μm. It was then dried at 100°C for 10 minutes. The dried, self-supporting polyamic acid film is peeled from the support and passed through a needle tenter frame equipped with needle plates. The ends of the film are held by inserting needles, and the needle plate spacing is adjusted to prevent the film from breaking or causing unnecessary slack. The film is heated at 200°C for 3 minutes, 250°C for 3 minutes, 300°C for 3 minutes, and 400°C for 3 minutes to carry out an imidization reaction. Then, it is cooled to room temperature for 2 minutes, and the poorly flat portions at both ends of the film are cut off using a slitting machine. The film is then wound into a roll to obtain a 200m long polyimide film A12 with a width of 450mm.

[0102] [Comparative Example 5] (Preparation of polyimide film A13) Using polyamic acid solution 4 (PAA-4) instead of polyamic acid solution 1 (PAA-1), and polyamic acid solution 2 (PAA-2) instead of polyimide solution 1 (PI-1), a polyimide film A13 with a width of 450 mm and a diameter of 20 μm was obtained in the same manner as in Example 2. Although a film was obtained, wrinkles occurred when it was wound into a roll.

[0103] <Thickness Measurement of Transparent High Heat-Resistant Laminated Films (Polyimide Films)> The thicknesses of polyimide films A1 to A11 were measured using a micrometer (Feinpruf, Millitron 1245D). The results are shown in Table 1.

[0104] <Tensile modulus of elasticity, tensile strength at break, and tensile elongation at break of transparent high-heat-resistant laminated film (polyimide film)> Each of the polyimide films A1 to A14 was cut into 100mm × 10mm strips in both the mechanical direction (MD direction) and the width direction (TD direction) to serve as test pieces. Using a tensile testing machine (Shimadzu Corporation, Autograph® model AG-5000A), the tensile modulus of elasticity, tensile strength at break, and tensile elongation at break were measured in both the MD and TD directions at a tensile speed of 50mm / min and a chuck spacing of 40mm.

[0105] Coefficient of linear expansion (CTE) of transparent high-heat-resistant laminated film (polyimide film) For polyimide films A1 to A14, the stretch rate is measured in the mechanical direction (MD direction) and the width direction (TD direction) under the following conditions: the stretch rate / temperature is measured at 15°C intervals in the manner of 30°C to 45°C and 45°C to 60°C. The measurement is carried out up to 300°C, and the average value of the total measured values ​​is calculated as CTE. Machine Name: MAC SCIENCE TMA4000S Sample length: 20mm Sample width: 2mm Starting temperature for heating: 25℃ End of heating temperature: 300℃ Heating rate: 5℃ / min Atmosphere: Argon

[0106] <Thickness direction phase difference (Rth) of transparent high heat-resistant laminated film (polyimide film)> The refractive indices nx (X-axis), ny (Y-axis), and nz (Z-axis) of polyimide films A1 to A14 were measured at room temperature (20–25°C) using light with a wavelength of 550 nm, employing an optical material inspection apparatus (model RETS-100) manufactured by Otsuka Electronics Co., Ltd. The optical axis was detected, and after phase lead-lag correction, the retardation was measured using a rotational analyzer method. Here, the X-axis and Y-axis represent the refractive index (nx) in the direction of maximum refractive index in the plane of the film, and the refractive index (ny) in the direction perpendicular to the Nx direction in the plane of the film. Then, based on the refractive index nx (X-axis), ny (Y-axis), and nz (Z-axis), and the film thickness (d), Rth was calculated using the following formula. Rth(nm)=|[nz-(nx+ny) / 2]×d|

[0107] <Heat shrinkage of transparent high heat-resistant laminated film (polyimide film)> In the determination of the coefficient of linear expansion (CTE) of the polyimide film, the temperature was raised to 300°C and then cooled to 80°C. The percentage of the length at 100°C during the initial heating to the length at 100°C during the cooling was calculated as the thermal shrinkage rate.

[0108] <Determination of Mixed Layer> The hybrid layer was fabricated using a SAICASDN-20S type (Daipla Wintes) to create a beveled surface of the polyimide film. This beveled surface was then measured using a Cary 620FTIR microscope (Agilent Technologies) with a germanium crystal and micro-ATR (30° incident angle). The results are shown in Table 1.

[0109] [Table 1]

[0110] <Warpage Measurement of Transparent High Heat-Resistant Laminated Film (Polyimide Film)> Polyimide films A1 to A14, cut to 30cm × 30cm, were conditioned for more than one day at 23℃ and 50% humidity. Warpage was then measured on a platform. The distance from the four corners of the film to the platform was measured. The average warpage at the four corners was taken as the warpage amount for each film.

[0111] Fabrication of a laminate with an inorganic substrate Method for applying silane coupling agents to glass substrates Figure 1 The experimental setup shown is used. Figure 1 This is a schematic diagram of the experimental setup for coating a silane coupling agent onto a glass substrate. The glass substrate used was OA11G glass (manufactured by NEG Corporation) with a thickness of 0.7 mm and a cut size of 100 mm × 100 mm. It should be noted that the glass substrate was washed with pure water, dried, and then irradiated with a UV / O3 irradiator (LAN TECHNICAL SKR1102N-03) for 1 minute to dry and wash it. 150 g of 3-aminopropyltrimethoxysilane (silane coupling agent Shin-Etsu Chemical KBM903) was added to a 1 L capacity reagent tank, and the hot water bath outside the tank was heated to 41 °C. The generated steam was then introduced into the chamber along with clean, dry air. The gas flow rate was 25 L / min, and the substrate temperature was 23 °C. The clean, dry air temperature was 23 °C, and the humidity was 1.2% RH. Since the exhaust was connected to a negative pressure exhaust port, a differential pressure gauge confirmed that the chamber had a negative pressure of approximately 2 Pa. The silane coupling agent coating time was set to 4 minutes. Then, a polyimide film (A1~A14, 70mm×70mm size) is laminated onto the above-mentioned silane coupling agent layer to obtain a laminate. At this time, the laminating surface is the side of layer (b). During lamination, a laminator manufactured by MCK Corporation is used, and the lamination conditions are set as follows: compressed air pressure: 0.6MPa, temperature: 22℃, humidity: 55%RH, lamination speed: 50mm / sec.

[0112] <Determination of 90° peel strength after heating at 300℃ for 1 hour> The laminate obtained in the above-described fabrication process was heat-treated at 100°C for 10 minutes under atmospheric conditions (pretreatment). Then, it was heated at 300°C for 1 hour under a nitrogen atmosphere. The 90° peel strength between the inorganic substrate and the polyimide film was then measured. The results are shown in Table 1. The conditions for determining the initial peel strength at 90° are shown below. The film is peeled off at a 90° angle relative to the inorganic substrate. Five measurements were performed, and the average value was taken as the measured value. Measuring apparatus: Autograph AG-IS manufactured by Shimadzu Corporation Measurement temperature: room temperature (25℃) Peeling speed: 100mm / min Atmosphere: Grand Sample width measured: 2.5cm

[0113] <Haze of transparent high-heat-resistant laminated film (polyimide film)> The haze of the polyimide film was measured using a HAZEMETER (NDH5000, manufactured by Nippon Denshoku Co., Ltd.). A D65 lamp was used as the light source. It should be noted that three identical measurements were performed, and the arithmetic mean was used.

[0114] Total light transmittance of the transparent high-heat-resistant laminated film (polyimide film) The total transmittance (TT) of the polyimide film was measured using a HAZEMETER (NDH5000, manufactured by Nippon Denshoku Co., Ltd.). A D65 lamp was used as the light source. It should be noted that the same measurement was performed three times, and the arithmetic mean was used.

[0115] <Color of transparent high heat-resistant laminated film (polyimide film)> Yellowness index was determined. Using a colorimeter (ZE6000, manufactured by Nippon Denko Co., Ltd.) and a C2 light source, the tristimulus values ​​(XYZ) of the polyimide film were measured according to ASTM D1925. The yellowness index (YI) was calculated using the following formula. It should be noted that three identical measurements were performed, and the arithmetic mean was used. YI = 100 × (1.28X - 1.06Z) / Y Symbol Explanation

[0116] 1. Flow meter 2 Gas inlet 3. Liquid tank (silane coupling agent tank) 4. Warm water bath (hot water bath) 5 heaters 6. Processing Chamber (Cavity) 7. Substrate 8. Exhaust port.

Claims

1. A transparent, high-heat-resistant laminated film with a total light transmittance of over 75%, characterized in that, It has an a layer, a b layer in contact with an inorganic substrate, and a hybrid layer at the interface between the a layer and the b layer. The hybrid layer is a layer in which the chemical composition contained in layer a and the chemical composition contained in layer b vary with a gradient. The thickness of the hybrid layer is 3 μm or more. Layer a: A layer containing a polyimide composition and with an inorganic filler content of less than 0.03% by mass. Layer b: A layer containing a polyimide composition and having an inorganic filler content of 0.03% by mass or more.

2. The transparent high heat-resistant laminated film according to claim 1, characterized in that, The thickness of the transparent, high-heat-resistant laminated film is between 5 μm and 200 μm.

3. The transparent high-heat-resistant laminated film according to claim 1 or 2, characterized in that, All layers comprising the a-layer and the b-layer of the transparent, heat-resistant laminate contain a polyimide composition.

4. The transparent high-heat-resistant laminated film according to claim 1 or 2, characterized in that, The transparent, high-heat-resistant laminated film consists only of layer a, the hybrid layer, and layer b.

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