Laminate containing a transparent, highly heat-resistant film

Abstract

The present invention provides a laminate that exhibits little warpage with an inorganic substrate and involves the use of a transparent film with high heat resistance having adequate heat resistance and suitably weak adhesive strength with an inorganic substrate, thus making it possible to perform various processes on the inorganic substrate and subsequently mechanically peel the inorganic substrate and the transparent film with high heat resistance apart.　The present invention relates to a laminate in which there is no substantial use of adhesives between a transparent film with high heat resistance and an inorganic substrate and wherein the lamination structure includes two or more layers of the transparent film with high heat resistance, the peeling strength with the inorganic substrate exceeds 0.3 N / cm, and the warpage amount of the laminate when heated to 300ºC is 1400 μm or less.

Description

[Technical Field]

[0001] The present invention relates to a laminate including a high heat resistant film. [Background technology]

[0002] In recent years, there has been an increasing demand for flexible and stretchable sheets on which multiple devices are mounted at intervals. Such sheets are expected to be worn on curved surfaces, such as the body. They are also expected to be used in electronic devices with bendable sections or rollable electronic devices. Transparent sheets offer promising applications, particularly in display applications, and are being actively explored.

[0003] Patent Document 1 discloses a method for producing a polyimide film for use as a support substrate in the manufacture of organic electroluminescent devices, which can be made thin, lightweight, and flexible, is free from problems such as cracking and peeling due to thermal stress, and has excellent dimensional stability. The method for producing a polyimide film for use as a support substrate for a display device involves applying a resin solution of polyimide or a polyimide precursor to a base substrate so that the polyimide film has a thickness of 50 μm or less, completing a heat treatment to form a polyimide film on the base substrate, and then separating the polyimide film from the base substrate. The polyimide film has a transmittance of 80% or more in the wavelength range from 440 nm to 780 nm and a transmittance of 80% or less at 400 nm. To separate the polyimide film from the base substrate, a laser beam is irradiated through the base substrate onto the bottom surface of the polyimide film. As exemplified in this method, forming a device on a film on glass is a highly practical method because it utilizes conventional processes for fabricating devices on glass.

[0004] Furthermore, Patent Document 2 describes a laminate having a silane coupling layer between an inorganic layer and a polyimide film layer, which has excellent heat resistance and insulation properties and is formed by laminating a polyimide film having higher levels of heat resistance and flexibility with an inorganic layer selected from a glass plate, a ceramic plate, a silicon wafer, and a metal, and states that this laminate can be realized by laminating films, which is an inexpensive and high-speed method, and is therefore extremely useful when used in the production of electronic devices, optical functional parts, electronic parts, etc. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2018-132768 [Patent Document 2] Patent No. 5304490 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the circuit board manufacturing method described in Patent Document 1, a single layer of film and glass are bonded together, but it is practically difficult to satisfy the various property requirements with a single layer using a conventional polyimide film. That is, when laminating with low-CTE glass, the film is required to have a low CTE, but low-CTE films are rare, and even if they do exist, they tend to peel easily. In addition, they generally tend to have poor mechanical properties. Furthermore, in the laminate described in Patent Document 2, a high peel strength is achieved that prevents peeling between the polyimide film and the inorganic substrate, but since the polyimides that can be used are actually limited, it is difficult to achieve both a low CTE and high levels of mechanical properties.

[0007] The present invention was made in consideration of the above-mentioned problems, and solved them by using a transparent, highly heat-resistant film with a laminated structure of two or more layers that combines a layer with high peel strength and a layer with a low CTE with an inorganic substrate. In other words, this patent is a glass device made by laminating a transparent, highly heat-resistant film and an inorganic substrate (glass). After peeling off the inorganic substrate, a flexible device can be created with the device mounted on the film. Having the film layer on the inorganic substrate (glass) makes it possible to create a device that can withstand cracks in the inorganic substrate (glass). It can be used for a variety of applications, such as: This prevents peeling of the transparent, highly heat-resistant film from the inorganic substrate during the process of forming devices on the transparent, highly heat-resistant film, facilitating the production of a film with electronic devices and providing a method for producing a device assembly that allows for mass production. Another object of the present invention is to provide a laminate of a transparent, highly heat-resistant film and an inorganic substrate for producing the device.

[0008] The present inventors have conducted extensive research into the manufacture of devices on transparent, highly heat-resistant films. As a result, they have found that the use of the following components makes it easy to manufacture devices on transparent, highly heat-resistant films and enables mass production, leading to the completion of the present invention. That is, the laminate according to the present invention has the following components:

[0009] [1] A laminate between a transparent, highly heat-resistant film and an inorganic substrate, which does not substantially use an adhesive, The laminate is characterized in that the transparent, highly heat-resistant film has a laminated structure of two or more layers, the peel strength with respect to the inorganic substrate is greater than 0.3 N / cm, and the amount of warping of the laminate after heating to 300°C is 1400 μm or less. [2] The laminate according to [1], wherein the first transparent, highly heat-resistant film layer in contact with the inorganic substrate has a CTE of 20 ppm / K or more by itself. [3] The laminate according to [1] or [2], wherein the transparent, highly heat-resistant film has a CTE of 40 ppm / K or less. [4] The laminate according to any one of [1] to [3], wherein the first transparent, highly heat-resistant film layer in contact with the inorganic substrate is made of a transparent polyimide. [5] The laminate according to any one of [1] to [4], wherein at least one layer of the second transparent, highly heat-resistant film layer that is not in contact with the inorganic substrate is made of a transparent polyimide. [6] The laminate according to any one of [1] to [5], wherein the first transparent, highly heat-resistant film layer in contact with the inorganic substrate contains a structure represented by formula 1. [ka] (In formula 1, R1 represents one or more selected from the group consisting of structures of formula 2, formula 3, formula 4, and formula 5. In formulas 2 to 5, * represents a bond to each imide group.) [ka] [ka] [ka] [ka] [7] The laminate according to any one of [1] to [6], wherein the inorganic substrate has a long side of 300 mm or more. [8] A method for producing a film with an electronic device, comprising forming an electronic device on the transparent, highly heat-resistant film according to any one of [1] to [7], and then peeling it off from the inorganic substrate. [Effects of the Invention]

[0010] According to the present invention, a laminate of a transparent, highly heat-resistant film having a low CTE and transparency, and having a high peel strength with respect to the inorganic substrate, and an inorganic substrate can be provided. Furthermore, since peeling between the transparent, highly heat-resistant film and the inorganic substrate does not occur during the process of forming devices on the transparent, highly heat-resistant film, the production of a film with electronic devices is easy, and a method for producing a device assembly that can be mass-produced can be provided. Furthermore, a laminate of the transparent, highly heat-resistant film and the inorganic substrate can be provided, and the laminate also has a small amount of warping when heated. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic diagram for explaining a silane coupling agent application method according to the present invention. [Figure 2] 1 is a schematic cross-sectional view illustrating a method for manufacturing a film with an electronic device according to the present invention. [Figure 3] 1 is another example of a schematic cross-sectional view illustrating the method for manufacturing a film with an electronic device according to the present invention. [Figure 4] 1 is a schematic cross-sectional view illustrating measurement of warpage of a laminate of a transparent, highly heat-resistant film and an inorganic substrate according to the present invention. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, an embodiment of the present invention will be described.

[0013] <Transparent, highly heat-resistant film> In this specification, a transparent, highly heat-resistant film is a film having a melting point of preferably 250°C or higher, more preferably 300°C or higher, and even more preferably 400°C or higher. It is also a film made of a polymer having a glass transition temperature of preferably 200°C or higher, more preferably 320°C or higher, and even more preferably 380°C or higher. Hereinafter, to avoid complexity, it will also be referred to simply as "polymer." In this specification, the melting point and glass transition temperature are determined by differential scanning calorimetry (DSC). If the melting point exceeds 500°C, it may be determined whether the melting point has been reached by visually observing the thermal deformation behavior when heated at the relevant temperature.

[0014] Regarding transparency, the total light transmittance is preferably 75% or more, more preferably 80% or more, even more 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 transparent, heat-resistant film, but for use as a film with an electronic device (hereinafter also referred to as a flexible electronic device), it is preferably 98% or less, more preferably 97% or less.

[0015] Examples of the transparent, highly heat-resistant film (hereinafter also simply referred to as a polymer film) include films of polyimide resins such as polyimide, polyamideimide, polyetherimide, and fluorinated polyimide (e.g., aromatic polyimide resins, alicyclic polyimide resins); copolymer polyesters such as polyethylene, polypropylene, polyethylene terephthalate, polybutylene terephthalate, and polyethylene-2,6-naphthalate (e.g., wholly aromatic polyesters, semi-aromatic polyesters); copolymer (meth)acrylates typified by polymethyl methacrylate; polycarbonate; polyamide; polysulfone; polyethersulfone; polyetherketone; cellulose acetate; cellulose nitrate; aromatic polyamide; polyvinyl chloride; polyphenol; polyarylate; polyacetal; modified polyphenylene ether; polyphenylene sulfide; polyphenylene oxide; polystyrene; polybenzoxazole; polybenzothiazole; polybenzimidazole; cyclic polyolefins; and liquid crystal polymers. Examples of such films include those reinforced with glass fillers, glass fibers, etc. However, since the polymer films are intended to be used in processes involving heat treatment at 250° C. or higher, only a limited number of the exemplified polymer films can actually be applied. Among the polymer films, preferred are films made of so-called super engineering plastics, and more specific 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, liquid crystal polymers, and the like.

[0016] A polyimide-based resin film (sometimes referred to as a polyimide film), an example of the polymer film, will be described in detail below. Generally, a polyimide-based resin film is obtained by applying a polyamic acid (polyimide precursor) solution obtained by reacting diamines and tetracarboxylic acids in a solvent to a support for polyimide film production, drying the solution, and then subjecting the green film to high-temperature heat treatment on the support for polyimide film production or after peeling it off the support to cause a dehydration ring-closing reaction. Here, the green film is a solvent-containing, self-supporting polyamic acid film. The solvent content of the green film is not particularly limited as long as it is self-supporting, but is preferably 1% by mass or more, more preferably 5% by mass or more, even more preferably 10% by mass or more, even more preferably 20% by mass or more, and particularly preferably 30% by mass or more. The solvent content is preferably 80% by mass or less, more preferably 70% by mass or less, even more preferably 60% by mass or less, and particularly preferably 50% by mass or less.

[0017] The polyamic acid (polyimide precursor) solution can be applied using any of the conventionally known solution application methods, such as spin coating, doctor blade, applicator, comma coater, screen printing, slit coating, reverse coating, dip coating, curtain coating, and slit die coating. The method of applying a polyamic acid solution to form a film offers a wide range of material options, making it easy to find a material that is suitable for easy peeling. However, it requires control of the imidization reaction. In contrast, film formation without the imidization reaction has the advantage of being easier to form, so it is necessary to use the appropriate method.

[0018] The polyimide film in the present invention is a polymer film having an imide bond in the main chain, and is preferably a polyimide film or a polyamideimide film, more preferably a polyimide film. A polyamide film is also preferred.

[0019] Generally, polyimide films are obtained by applying a polyamic acid (polyimide precursor) solution obtained by reacting diamines and tetracarboxylic acids in a solvent to a polyimide film support, drying the solution to form a green film (also called a "precursor film" or "polyamic acid film"). The green film is then subjected to high-temperature heat treatment on the polyimide film support or after being peeled off the support to cause a dehydration ring-closing reaction. Alternatively, a polyimide solution obtained by the dehydration ring-closing reaction of diamines and tetracarboxylic acids in a solvent is applied to a polyimide film support, drying the resulting polyimide film containing 1 to 50 wt. % solvent, and then drying the polyimide film containing 1 to 50 wt. % solvent at a high temperature on the polyimide film support or after being peeled off the support.

[0020] Generally, a polyamideimide film is obtained by applying a polyamideimide solution obtained by reacting diisocyanates with tricarboxylic acids in a solvent to a support for producing the polyamideimide film, drying the solution to form a polyamideimide film containing 1 to 50% by weight of solvent, and then subjecting the polyamideimide film containing 1 to 50% by weight of solvent to high-temperature treatment and drying on the support for producing the polyamideimide or after peeling it off from the support.

[0021] Generally, a polyamide film is obtained by applying a polyamide solution obtained by reacting diamines and dicarboxylic acids in a solvent to a support for producing the polyamide film, drying the solution to form a polyamide film containing 1 to 50% by weight of solvent, and then further treating the polyamide film containing 1 to 50% by weight of solvent at a high temperature on the support for producing the polyamide or after peeling it off from the support and drying it.

[0022] Examples of the tetracarboxylic acids, tricarboxylic acids, and dicarboxylic acids that can be used include aromatic tetracarboxylic acids (including their acid anhydrides), aliphatic tetracarboxylic acids (including their acid anhydrides), alicyclic tetracarboxylic acids (including their acid anhydrides), aromatic tricarboxylic acids (including their acid anhydrides), aliphatic tricarboxylic acids (including their acid anhydrides), alicyclic tricarboxylic acids (including their acid anhydrides), aromatic dicarboxylic acids, aliphatic dicarboxylic acids, and alicyclic dicarboxylic acids, which are commonly used in polyimide synthesis, polyamideimide synthesis, and polyamide synthesis. Among these, aromatic tetracarboxylic acid anhydrides and aliphatic tetracarboxylic acid anhydrides are preferred, with aromatic tetracarboxylic acid anhydrides being more preferred from the viewpoint of heat resistance, and alicyclic tetracarboxylic acids being more preferred from the viewpoint of light transmittance. When the tetracarboxylic acid is an acid anhydride, it may have one or two anhydride structures in the molecule, but preferably has two anhydride structures (dianhydrides). The tetracarboxylic acids, tricarboxylic acids, and dicarboxylic acids may be used alone or in combination of two or more.

[0023] Examples of aromatic tetracarboxylic acids for obtaining a colorless and highly transparent polyimide in the present invention include 4,4'-(2,2-hexafluoroisopropylidene)diphthalic acid, 4,4'-oxydiphthalic acid, 3,4'-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)benzene-1,4-dicarboxylate, 4,4'-[4,4'-(3-oxo-1,3-dihydro-2-benzofuran-1,1 -diyl)bis(benzene-1,4-diyloxy)]dibenzene-1,2-dicarboxylic acid, 3,3',4,4'-benzophenonetetracarboxylic acid, 4,4'-[(3-oxo-1,3-dihydro-2-benzofuran-1,1-diyl)bis(toluene-2,5-diyloxy)]dibenzene-1,2-dicarboxylic acid, 4,4'-[(3-oxo-1,3-dihydro-2-benzofuran-1,1-diyl)bis(1,4-xylene-2,5-diyloxy)]dibenzene-1,2-dicarboxylic acid, 4,4'-[4,4'-(3-oxo-1, 3-dihydro-2-benzofuran-1,1-diyl)bis(4-isopropyl-toluene-2,5-diyloxy)]dibenzene-1,2-dicarboxylic acid, 4,4'-[4,4'-(3-oxo-1,3-dihydro-2-benzofuran-1,1-diyl)bis(naphthalene-1,4-diyloxy)]dibenzene-1,2-dicarboxylic acid, 4,4'-[4,4'-(3H-2,1-benzoxathiol-1,1-dioxide-3,3-diyl)bis(benzene-1,4-diyloxy)]dibenzene-1,2-dicarboxylic acid, 4,4'-benzo Dibenzophenonetetracarboxylic acid, 4,4'-[(3H-2,1-benzoxathiol-1,1-dioxide-3,3-diyl)bis(toluene-2,5-diyloxy)]dibenzene-1,2-dicarboxylic acid, 4,4'-[(3H-2,1-benzoxathiol-1,1-dioxide-3,3-diyl)bis(1,4-xylene-2,5-diyloxy)]dibenzene-1,2-dicarboxylic acid, 4,4'-[4,4'-(3H-2,1-benzoxathiol-1,1-dioxide-3,3-diyl)bis(4-isopropyl-toluene-2,5-diyloxy)]dibenzene-1,2-dicarboxylic acid, 4,4'-[4,4'-(3H-2,1-benzoxathiol-1,1-dioxide-3,3-diyl)bis(naphthalene-1,4-diyloxy)]dibenzene-1,2-dicarboxylic acid, 3,3',4,4'-diphenylsulfonetetracarboxylic acid, 3,3',4,4'-biphenyltetracarboxylic acid, 2,3,3',4'-biphenyltetracarboxylic acid, 2,2',3, Examples of suitable tetracarboxylic acids include 3'-biphenyltetracarboxylic acid, 2,2'-diphenoxy-4,4',5,5'-biphenyltetracarboxylic acid, pyromellitic acid, 4,4'-[spiro(xanthene-9,9'-fluorene)-2,6-diylbis(oxycarbonyl)]diphthalic acid, and 4,4'-[spiro(xanthene-9,9'-fluorene)-3,6-diylbis(oxycarbonyl)]diphthalic acid, as well as their acid anhydrides. Among these, dianhydrides having two acid anhydride structures are preferred, with 4,4'-(2,2-hexafluoroisopropylidene)diphthalic dianhydride and 4,4'-oxydiphthalic dianhydride being particularly preferred. The aromatic tetracarboxylic acids may be used alone or in combination of two or more. When heat resistance is important, the aromatic tetracarboxylic acids preferably account for 50% by mass or more of the total tetracarboxylic acids, more preferably 60% by mass or more, even more 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, and bicyclo[2,2,2]oct-7-ene-2,3,5,6-tetracarboxylic acid. carboxylic acid, tetrahydroanthracene-2,3,6,7-tetracarboxylic acid, tetradecahydro-1,4:5,8:9,10-trimethanoanthracene-2,3,6,7-tetracarboxylic acid, decahydronaphthalene-2,3,6,7-tetracarboxylic acid, decahydro-1,4:5,8-dimethanonaphthalene-2,3,6,7-tetracarboxylic acid, decahydro-1,4-ethano-5,8-methanonaphthalene-2,3,6,7-tetracarboxylic acid, norbornane-2-spiro-α-cyclopentanone-α'-spiro-2''-norbornane -5,5'',6,6''-tetracarboxylic acid (synonym: 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 (synonym: norbornane-2-spiro pyro-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-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-cyclotridecanone-α'-spiro-2''-norbornane-5,5'',6,6''-tetracarboxylic acid, norbornane-2-spiro-α-cyclotetradecanone-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, and norbornane-2-spiro-α-(methylcyclohexanone)-α'-spiro-2''-norbornane-5,5'',6,6''-tetracarboxylic acid, and acid anhydrides thereof. Among these, dianhydrides having two acid anhydride structures are preferred, and in particular, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4-cyclohexanetetracarboxylic dianhydride, and 1,2,4,5-cyclohexanetetracarboxylic dianhydride are preferred, and 1,2,3,4-cyclobutanetetracarboxylic dianhydride and 1,2,4,5-cyclohexanetetracarboxylic dianhydride are more preferred, and 1,2,3,4-Cyclobutanetetracarboxylic dianhydride is more preferred. These may be used alone or in combination of two or more. When transparency is important, the alicyclic tetracarboxylic acids preferably account for 50% by mass or more of the total tetracarboxylic acids, more preferably 60% by mass or more, even more preferably 70% by mass or more, and even more preferably 80% by mass or more.

[0025] Examples of tricarboxylic acids include aromatic tricarboxylic acids such as trimellitic acid, 1,2,5-naphthalenetricarboxylic acid, diphenylether-3,3',4'-tricarboxylic acid, and diphenylsulfone-3,3',4'-tricarboxylic acid, hydrogenated versions of these aromatic tricarboxylic acids such as hexahydrotrimellitic acid, alkylene glycol bistrimellitates such as ethylene glycol bistrimellitate, propylene glycol bistrimellitate, 1,4-butanediol bistrimellitate, and polyethylene glycol bistrimellitate, and monoanhydrides and esters thereof. Among these, monoanhydrides having one acid anhydride structure are preferred, with trimellitic anhydride and hexahydrotrimellitic anhydride being particularly preferred. These may be used alone or in combination.

[0026] Examples of dicarboxylic acids include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, orthophthalic acid, naphthalenedicarboxylic acid, and 4,4'-oxydibenzenecarboxylic acid, hydrogenated versions of these aromatic dicarboxylic acids such as 1,6-cyclohexanedicarboxylic acid, oxalic acid, succinic acid, glutaric acid, adipic acid, heptanedioic acid, octanedioic acid, azelaic acid, sebacic acid, undecadioic acid, dodecanedioic acid, and 2-methylsuccinic acid, as well as their acid chlorides and esters. Among these, aromatic dicarboxylic acids and their hydrogenated versions are preferred, with terephthalic acid, 1,6-cyclohexanedicarboxylic acid, and 4,4'-oxydibenzenecarboxylic acid being particularly preferred. The dicarboxylic acids may be used alone or in combination.

[0027] The diamines or isocyanates used to obtain the colorless and highly transparent polyimide of the present invention are not particularly limited, and aromatic diamines, aliphatic diamines, alicyclic diamines, aromatic diisocyanates, aliphatic diisocyanates, alicyclic diisocyanates, and the like, which are commonly used in polyimide synthesis, polyamideimide 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, the use of aromatic diamines having a benzoxazole structure makes it possible to achieve high heat resistance, as well as a high elastic modulus, low heat shrinkage, and a low coefficient of linear expansion. The diamines and isocyanates may 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'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 4,4'-bis(4-aminophenoxy)biphenyl, 4,4'-bis(3-aminophenoxy)biphenyl, bis[4-(3-aminophenoxy)phenyl]ketone, and bis[4-(3-aminophenoxy)phenyl] Sulfide, bis[4-(3-aminophenoxy)phenyl]sulfone, 2,2-bis[4-(3-aminophenoxy)phenyl]propane, 2,2-bis[4-(3-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, 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'-diaminobenzo Phenone, 3,4'-diaminobenzophenone, 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, 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)phenyl] )-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)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, 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-(4-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]diphenone Nilsulfone, 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-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 3,3'-Diamino-4,4'-Diamino-5'-Phenoxybenzophenone, 3,3'-Diamino-4,4'-Diamino-5,5'-Diamino-5'-Diamino-4'-Diamino-5'-Diamino-4'-Diamino-5'-Diamino-4'-Diamino-5'-Diamino-4'-Diamino-5'-Diamino-4'-Diamino-5'-Diamino-4'-Diamino-5'-Diamino-4'-Diamino-5'-Diamino-4'-Diamino-5'-Diamino-1,3-Bis(3-amino-4-phenoxybenzoyl)benzene, 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]benzonitrile, 4,4'-[9H-fluorene-9,9-diyl]bisaniline (also known as "9,9-bis(4-aminophenyl)fluorene"), spiro(xanthene-9,9'-fluorene)-2,6-diylbis (oxycarbonyl)]bisaniline, 4,4'-[spiro(xanthene-9,9'-fluorene)-2,6-diylbis(oxycarbonyl)]bisaniline, 4,4'-[spiro(xanthene-9,9'-fluorene)-3,6-diylbis(oxycarbonyl)]bisaniline, 9,10-bis(4-aminophenyl)adenine, dimethyl 2,4-bis(4-aminophenyl)cyclobutane-1,3-dicarboxylate, and aromatic diamines in which some or all of the hydrogen atoms on the aromatic ring of the above aromatic diamines have been substituted with halogen atoms, alkyl or alkoxy groups having 1 to 3 carbon atoms, cyano groups, or halogenated alkyl or alkoxy groups having 1 to 3 carbon atoms in which some or all of the hydrogen atoms of the alkyl or alkoxy groups have been substituted with halogen atoms. The aromatic diamines having a benzoxazole structure are not particularly limited, and examples thereof 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), 1-(5-aminobenzoxazolo)-4-(6-aminobenzoxazolo)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, and the like. Among these, 2,2'-ditrifluoromethyl-4,4'-diaminobiphenyl, 4-amino-N-(4-aminophenyl)benzamide, 4,4'-diaminodiphenyl sulfone, and 3,3'-diaminobenzophenone are particularly preferred. The aromatic diamines may be used alone or in combination.

[0029] Examples of alicyclic diamines include 1,4-diaminocyclohexane, 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-diaminocyclohexane and 1,4-diamino-2-methylcyclohexane are particularly preferred, and 1,4-diaminocyclohexane is more preferred. The alicyclic diamines may 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, 3,2'- or 3,3'- or 4,2'- or 4,3'- or 5,2'- or 5,3'- or 6,2'- or 6,3'-diethyl 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'-dimethoxydiphenylmethane-2,4'-diisocyanate, diphenylmethane-4,4'-diisocyanate, diphenylmethane-3,3'-diisocyanate, diphenylmethane-3,4'-diisocyanate, diphenylether-4,4' -Diisocyanate, benzophenone-4,4'-diisocyanate, diphenylsulfone-4,4'-diisocyanate, tolylene-2,4-diisocyanate, tolylene-2,6-diisocyanate, m-xylylene diisocyanate, p-xylylene 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'-di Examples of the diisocyanate include aromatic diisocyanates such as ethylbiphenyl-4,4'-diisocyanate, 3,3'-dimethoxybiphenyl-4,4'-diisocyanate, and 3,3'-diethoxybiphenyl-4,4'-diisocyanate, and diisocyanates obtained by hydrogenating any of these (for example, isophorone diisocyanate, 1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, and hexamethylene diisocyanate).Among these, diphenylmethane-4,4'-diisocyanate, tolylene-2,4-diisocyanate, tolylene-2,6-diisocyanate, 3,3'-dimethylbiphenyl-4,4'-diisocyanate, naphthalene-2,6-diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, and 1,4-cyclohexane diisocyanate are preferred from the viewpoints of low moisture absorption, dimensional stability, cost, and polymerizability. The diisocyanates may be used alone or in combination.

[0031] The transparent, highly heat-resistant film preferably contains the structure of the following formula 1, since this provides good transparency. In particular, it is preferable that the first transparent, highly heat-resistant film in contact with the inorganic substrate contains the structure of the following formula 1. [ka] (In formula 1, R1 represents one or more selected from the group consisting of the structure of formula 2, the structure of formula 3, the structure of formula 4, and the structure of formula 5. In formulas 2 to 5, * represents a bond to each imide group.) [ka] [ka] [ka] [ka]

[0032] The transparent, highly heat-resistant film of the present invention may have a single layer structure or a laminate structure of two or more layers. In view of the physical strength of the transparent, highly heat-resistant film and its ease of peeling from the inorganic substrate, a laminate structure of two or more layers is preferred, and a laminate structure of three or more layers is also acceptable. In this specification, when the transparent, highly heat-resistant film has a laminate structure of two or more layers, the physical properties (yellowness index, total light transmittance, haze, etc.) refer to the values of the entire transparent, highly heat-resistant film unless otherwise specified.

[0033] The yellowness index (hereinafter also referred to as "yellow index" or "YI") of the transparent, highly heat-resistant film of the present invention is preferably 10 or less, more preferably 7 or less, even more preferably 5 or less, and still more preferably 3 or less. There is no particular lower limit for the yellowness index of the transparent, highly heat-resistant film, but for use as a flexible electronic device, it is preferably 0.1 or more, more preferably 0.2 or more, and even more preferably 0.3 or more.

[0034] The transparent, highly heat-resistant film of the present invention preferably has a light transmittance at a wavelength of 400 nm of 70% or more, more preferably 72% or more, even more preferably 75% or more, and even more preferably 80% or more. There is no particular upper limit to the light transmittance at a wavelength of 400 nm of the transparent, highly heat-resistant film, but for use as a flexible electronic device, it is preferably 99% or less, more preferably 98% or less, and even more preferably 97% or less.

[0035] The transparent, heat-resistant film of the present invention preferably has a total light transmittance of 75% or more, more preferably 85% or more, even more preferably 87% or more, and even more preferably 88% or more. There is no particular upper limit to the total light transmittance of the polyimide film, but for use as a flexible electronic device, it is preferably 98% or less, more preferably 97% or less.

[0036] The haze of the transparent, highly heat-resistant film of the present invention is preferably 1.0 or less, more preferably 0.8 or less, even more preferably 0.5 or less, and even more preferably 0.3 or less.

[0037] The thickness of the transparent, highly heat-resistant film in the present 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 transparent, highly heat-resistant film, but for use as a flexible electronic device, it is preferably less than 40 μm, more preferably 35 μm or less, and even more preferably 30 μm or less. If the film is too thin, it is difficult to produce and transport the film, and if it is too thick, it becomes difficult to transport it by roll. The colorless and highly transparent polyimide film of the present invention, which exhibits a high coefficient of linear expansion (CTE), can also be achieved by stretching the polyimide film during its formation. This stretching procedure involves applying a polyimide solution to a support for polyimide film preparation, drying the solution to form a polyimide film containing 1 to 50% by mass of solvent, and then stretching the polyimide film containing 1 to 50% by mass of solvent at a high temperature on the support or after peeling it from the support, 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. Using an unstretched thermoplastic polymer film as the support for polyimide film preparation, stretching the thermoplastic polymer film and polyimide film simultaneously, and then peeling the stretched polyimide film from the thermoplastic polymer film, can prevent scratches on the polyimide film, especially during MD stretching, and produce a higher-quality, colorless and highly transparent polyimide film.

[0038] The average coefficient of linear expansion (CTE) of the transparent, highly heat-resistant film between 30°C and 300°C is preferably 50 ppm / K or less. It is more preferably 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. It is also preferably -5 ppm / K or more, more preferably -3 ppm / K or more, and even more preferably 1 ppm / K or more. A CTE within this range can minimize the difference in linear expansion coefficient from that of a typical support (inorganic substrate), preventing peeling between the transparent, highly heat-resistant film and the inorganic substrate or warping of the support during a heat treatment process. Here, CTE is a factor that represents reversible expansion and contraction with temperature. The CTE of the transparent, highly heat-resistant film refers to the average value of the CTE in the machine direction (MD) and the width direction (TD) of the transparent, highly heat-resistant film. The CTE of the transparent, highly heat-resistant film is measured according to the method described in the Examples.

[0039] The transparent, highly heat-resistant film may contain a lubricant (filler). Examples of the lubricant include, but are not limited to, silica, carbon, and ceramic, with silica being preferred. These lubricants may be used alone or in combination. The average particle size of the lubricant is preferably 10 nm or more, more preferably 30 nm or more, and even more preferably 50 nm or more. It is also preferably 1 μm or less, more preferably 500 nm or less, and even more preferably 100 nm or less. The content of the lubricant in the transparent, highly heat-resistant film is preferably 0.01% by mass or more. Since this improves the smoothness of the transparent, highly heat-resistant film, it is more preferably 0.02% by mass or more, even more preferably 0.05% by mass or more, and particularly preferably 0.1% by mass or more. From the viewpoint of transparency, it is preferably 5% by mass or less, more preferably 3% by mass or less, even more preferably 2% by mass or less, and particularly preferably 1% by mass or less.

[0040] Furthermore, when the transparent, highly heat-resistant film has a laminated structure of two or more layers, the difference in CTE between each layer is undesirable because it can cause warping. Therefore, the difference in CTE between the first transparent, highly heat-resistant film layer in contact with the inorganic substrate and the second transparent, highly heat-resistant film layer adjacent to the first transparent, highly heat-resistant film without contacting the inorganic substrate is preferably 40 ppm / K or less, more preferably 30 ppm / K or less, and even more preferably 15 ppm / K or less. In particular, it is preferable that the thickest layer of the second transparent, highly heat-resistant film be within the above range. Furthermore, it is preferable that the transparent, highly heat-resistant film has a symmetrical structure in the thickness direction, as this makes it less likely to warp.

[0041] The CTE of the first transparent, highly heat-resistant film alone is preferably 20 ppm / K or less. Since the difference in CTE from the inorganic substrate is small, it is more preferably 15 ppm / K or less, and even more preferably 10 ppm / K or less. There is no lower limit, but for use in flexible electronic devices, it is preferably -10 ppm / K or more, more preferably -5 ppm / K or more, and even more preferably 1 ppm / K or more. The CTE of the first transparent, highly heat-resistant film refers to the average value of the CTE in the machine direction (MD) and the CTE in the width direction (TD) of the transparent, highly heat-resistant film, and is measured according to the method described in the Examples.

[0042] The first transparent, highly heat-resistant film is preferably a transparent polyimide. When the second transparent, highly heat-resistant film has a laminated structure of multiple layers, at least one layer of the second transparent, highly heat-resistant film is preferably a transparent polyimide, and the thickest layer of the second transparent, highly heat-resistant film is more preferably a transparent polyimide. Even more preferably, all layers of the second transparent, highly heat-resistant polyimide are transparent polyimide.

[0043] The first transparent, highly heat-resistant film layer in contact with the inorganic substrate preferably contains a polyimide having the structure of Formula 1 and / or Formula 2 below. The total amount of polyimides having the structures of Formula 1 and Formula 2 in the first transparent, highly heat-resistant film layer is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and particularly preferably 95% by mass or more, and may even be 100% by mass or more. By containing the polyimide having the structure of Formula 1 and / or Formula 2 within the above range, the first transparent, highly heat-resistant film can exhibit an excellent CTE. Furthermore, when there is significant intermixing between the transparent, highly heat-resistant film layers, or by approaching a symmetrical structure in the film thickness direction, the warpage of the laminate is also improved. [ka] [ka]

[0044] The heat shrinkage of the transparent, highly heat-resistant film is preferably ±0.9%, more preferably ±0.6%, between 30° C. and 500° C. The heat shrinkage is a factor that indicates irreversible expansion and contraction with respect to temperature.

[0045] The tensile strength at break of the transparent, highly heat-resistant film is preferably 60 MPa or more, more preferably 120 MPa or more, and even more preferably 240 MPa or more. The upper limit of the tensile strength at break is not particularly limited, but is practically less than about 1000 MPa. A tensile strength at break of 60 MPa or more can prevent the transparent, highly heat-resistant film from breaking when peeled from an inorganic substrate. The tensile strength at break of the transparent, highly heat-resistant film refers to the average value of the tensile strength at break in the machine direction (MD) and the tensile strength at break in the width direction (TD) of the transparent, highly heat-resistant film. The tensile strength at break of the transparent, highly heat-resistant film is measured by the method described in the Examples. Even when the film is prepared by applying the film to a glass substrate using a casting applicator, the two orthogonal directions, parallel and perpendicular to the application by the casting applicator, are defined as the MD and TD directions, respectively. The same applies to the tensile elongation at break and the tensile modulus below.

[0046] The tensile elongation at break of the transparent, highly heat-resistant film is preferably 1% or more, more preferably 5% or more, and even more preferably 20% or more. When the tensile elongation at break is 1% or more, the film has excellent handleability. The tensile elongation at break of the transparent, highly heat-resistant film refers to the average value of the tensile elongation at break in the machine direction (MD) and the tensile elongation at break in the width direction (TD) of the transparent, highly heat-resistant film. The tensile elongation at break of the transparent, highly heat-resistant film is measured by the method described in the Examples.

[0047] The tensile modulus of the transparent, highly heat-resistant film is preferably 2 GPa or more, more preferably 3 GPa or more, and even more preferably 4 GPa or more. When the tensile modulus is 3 GPa or more, the transparent, highly heat-resistant film undergoes little elongation deformation when peeled off from the inorganic substrate, resulting in excellent handleability. The tensile modulus is preferably 20 GPa or less, more preferably 12 GPa or less, and even more preferably 10 GPa or less. When the tensile modulus is 20 GPa or less, the transparent, highly heat-resistant film can be used as a flexible film. The tensile modulus of the transparent, highly heat-resistant film refers to the average value of the tensile modulus in the machine direction (MD) and the width direction (TD) of the high heat-resistant film. The tensile modulus of the transparent, highly heat-resistant film is measured according to the method described in the Examples.

[0048] The thickness unevenness of the transparent, highly heat-resistant 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 unevenness exceeds 20%, it tends to be difficult to apply to narrow areas. The thickness unevenness of the transparent, highly heat-resistant film can be calculated, for example, by measuring the film thickness at approximately 10 randomly selected positions on the film to be measured using a contact-type film thickness meter and then using the following formula: Film thickness unevenness (%) = 100 x (maximum film thickness - minimum film thickness) ÷ average film thickness

[0049] The transparent, highly heat-resistant film is preferably obtained in the form of a long, transparent, highly heat-resistant film wound up during production, having a width of 300 mm or more and a length of 10 m or more, and more preferably in the form of a roll-shaped transparent, highly heat-resistant film wound up on a winding core. When the transparent, highly heat-resistant film is wound up in a roll, it can be easily transported in the form of a roll-shaped transparent, highly heat-resistant film.

[0050] In order to ensure the handling properties and productivity of the transparent, highly heat-resistant film, it is preferable to add or contain approximately 0.03 to 3 mass % of a lubricant (particles) having a particle diameter of approximately 10 to 1000 nm to the transparent, highly heat-resistant film, thereby imparting fine irregularities to the surface of the transparent, highly heat-resistant film and ensuring slipperiness.

[0051] In the transparent, highly heat-resistant film having a laminated structure of two or more layers, it is desirable that there is intermixing, particularly at the interface between the first transparent, highly heat-resistant film layer in contact with the inorganic substrate and the second transparent, highly heat-resistant film layer adjacent to the first transparent, highly heat-resistant film layer (hereinafter simply referred to as the "second transparent, highly heat-resistant film layer"). If the thickness of the intermixing is small, the transparent, highly heat-resistant film may warp or peel between the layers due to differences in the physical properties of the individual layers. Therefore, the thickness of the intermixing is preferably 800 nm or more, more preferably 1000 nm or more, and particularly preferably 2000 nm or more. If the thickness of the intermixing is too large, the total thickness must be increased, and the intermixing may occur on the outermost surface of the transparent, highly heat-resistant film, making it difficult to form a thin film. The upper limit is determined by the film thickness. Although there are no particular limitations, from an industrial perspective, a thickness of 5 μm or less is acceptable, and preferably 3 μm or less.

[0052] The means for forming a highly intermixed layer is not particularly limited, but is preferably a solution-casting method in which two layers, a first transparent, highly heat-resistant film layer and a second transparent, highly heat-resistant film layer, are simultaneously or sequentially coated (hereinafter also referred to as "simultaneous and sequential coating"), allowing the solutions to diffuse into each other and forming an integrated film. If the first layer is heated (dried) and then the next layer (second layer) is formed (coated), the intermixed layer will be smaller than in the case of simultaneous and sequential coating, regardless of whether the heating process is intermediate or completed. However, even if the heating (drying) is partially completed, for example, if a solution containing a large amount of solvent is applied to the second layer and time is allowed for the solvent to diffuse, the intermixed layer will often be smaller than in the case of simultaneous and sequential coating, but intermixing itself will be promoted. Furthermore, even if the layer is heated (dried) partway through, for example, if a solvent is applied on the second layer to promote the diffusion of the solvent, the amount of mixed layer is often smaller than when the layers are applied simultaneously or sequentially, but the mixing itself is promoted.

[0053] By using two layers of materials (resins) with different physical properties, it is possible to create a film with a variety of properties. Furthermore, by laminating layers in a symmetrical structure in the thickness direction (for example, a first transparent, highly heat-resistant film layer / a second transparent, highly heat-resistant film layer / a first transparent, highly heat-resistant film layer), the CTE of the entire film is well balanced, making it less prone to warping. Furthermore, by making one of the layers absorb ultraviolet or infrared light, it is possible to give the film distinctive spectral characteristics, and to control the incidence and emission of light using layers with different refractive indices.

[0054] There are various methods for producing films with two or more layers, such as simultaneous coating using a T-die that can simultaneously eject two layers, sequential coating in which one layer is coated and then the next layer is coated, a method in which one layer is coated and then dried before coating the next layer, a method in which one layer is formed into a film and then the next layer is coated, or multi-layering by heat lamination by adding a thermoplastic layer, and this patent can incorporate various existing coating methods and multi-layering techniques as appropriate.

[0055] The thickness of the first transparent, highly heat-resistant film is preferably 1 μm or more. Since this makes it less susceptible to the influence of mixing, it is more preferably 2 μm or more, and even more preferably 3 μm or more. Furthermore, from the viewpoint of reducing the overall thickness of the transparent, highly heat-resistant film, it is preferably 10 μm or less, more preferably 8 μm or less, and even more preferably 5 μm or less.

[0056] <Inorganic substrate> The inorganic substrate may be any plate-like substrate that can be used as a substrate made of an inorganic material, and examples thereof include those that are mainly made of glass plates, ceramic plates, semiconductor wafers, metals, etc., and composites of these glass plates, ceramic plates, semiconductor wafers, and metals, such as laminates of these plates, composites in which these plates are dispersed, and composites in which fibers of these plates are contained.

[0057] Examples of the glass plate include quartz glass, high silicate glass (96% silica), soda-lime glass, lead glass, aluminoborosilicate glass, borosilicate glass (Pyrex (registered trademark)), borosilicate glass (alkali-free), borosilicate glass (microsheet), aluminosilicate glass, etc. Among these, glass plates with a linear expansion coefficient of 5 ppm / K or less are preferred, and commercially available products such as liquid crystal glass such as Corning (registered trademark) 7059, Corning (registered trademark) 1737, and EAGLE manufactured by Corning Incorporated, AN100 manufactured by Asahi Glass Co., Ltd., OA10 and OA11G manufactured by Nippon Electric Glass Co., Ltd., and AF32 manufactured by SCHOTT are preferred.

[0058] The semiconductor wafer is not particularly limited, but examples include wafers of silicon wafers, germanium, silicon-germanium, gallium-arsenic, aluminum-gallium-indium, nitrogen-phosphorus-arsenic-antimony, SiC, InP (indium phosphide), InGaAs, GaInNAs, LT, LN, ZnO (zinc oxide), CdTe (cadmium telluride), ZnSe (zinc selenide), etc. Among these, the wafers that are preferably used are silicon wafers, and particularly preferred are mirror-polished silicon wafers having a size of 8 inches or more.

[0059] Examples of the metals include single-element metals such as W, Mo, Pt, Fe, Ni, and Au, as well as alloys such as Inconel, Monel, nimonic, copper carbon, Fe-Ni-based Invar alloys, and Super Invar alloys. Multilayer metal plates formed by adding other metal layers or ceramic layers to these metals are also included. In this case, Cu, Al, and the like can be used for the main metal layer as long as the overall coefficient of linear expansion (CTE) with the additional layers is low. Metals used for the additional metal layer are not limited as long as they have properties such as strong adhesion to the high-heat-resistant film, no diffusion, and good chemical and heat resistance. Suitable examples include Cr, Ni, TiN, and Cu containing Mo.

[0060] The ceramic plate in the present invention includes ceramic substrates such as Al2O3, Mullite, AlN, SiC, crystallized glass, Cordierite, Spodumene, Pb-BSG+CaZrO3+Al2O3, Crystallized glass+Al2O3, Crystallized Ca-BSG, BSG+Quartz, BSG+Quartz, BSG+Al2O3, Pb-BSG+Al2O3, Glass-ceramic, and Zerodur material.

[0061] The planar portion of the 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 the surface is rougher than this, the peel strength between the transparent, highly heat-resistant film layer and the inorganic substrate may be insufficient. The thickness of the inorganic substrate is not particularly limited, but from the viewpoint of ease of handling, a thickness of 10 mm or less is preferred, more preferably 3 mm or less, and even more preferably 1.3 mm or less. There is no particular limit to the lower limit of the thickness, but it is preferably 0.07 mm or more, more preferably 0.15 mm or more, and even more preferably 0.3 mm or more. If it is too thin, it will be easily broken and difficult to handle. If it is too thick, it will be heavy and difficult to handle.

[0062] <Laminate> The laminate of the present invention is obtained by laminating the transparent, highly heat-resistant film and the inorganic substrate substantially without using an adhesive. When the transparent, highly heat-resistant film has a laminate structure of two or more layers, it preferably contains the first transparent, highly heat-resistant film in contact with the inorganic substrate and a second transparent, highly heat-resistant film layer adjacent to the first transparent, highly heat-resistant film layer without contacting the inorganic substrate. The second transparent, highly heat-resistant film may further have a multi-layer structure. Furthermore, the laminate may have a structure in which both ends in the thickness direction of the laminate are inorganic substrates (e.g., inorganic substrate / first transparent, highly heat-resistant film / second transparent, highly heat-resistant film / first transparent, highly heat-resistant film / inorganic substrate). In this case, the transparent, highly heat-resistant film and the inorganic substrate at both ends are bonded substantially without using an adhesive.

[0063] The shape of the laminate is not particularly limited, and may be square or rectangular. A rectangular shape is preferred, with the long side preferably being 300 mm or longer, more preferably 500 mm or longer, and even more preferably 1000 mm or longer. There is no particular upper limit, but it is desirable that it can replace substrates of the size and material used industrially. A length of 20,000 mm or shorter is sufficient, and a length of 10,000 mm or shorter is acceptable.

[0064] The laminate of the present invention has a warpage of 1400 μm or less when heated at 300° C. To improve heat resistance, the warpage is preferably 900 μm or less, and more preferably 400 μm or less. There are no particular restrictions on the lower limit of the warpage, but from an industrial perspective, a warpage of 50 μm or more is sufficient, and even 100 μm or more is acceptable.

[0065] <Adhesive> In the present invention, substantially no adhesive layer is interposed between the inorganic substrate and the transparent, highly heat-resistant film. Here, the adhesive layer referred to in the present invention refers to one containing less than 10% by mass of silicon (Si) (less than 10% by mass). Furthermore, "substantially not used (not interposed)" means that the thickness of the adhesive layer interposed between the inorganic substrate and the transparent, highly heat-resistant film is preferably 0.4 μm or less, more preferably 0.1 μm or less, even more preferably 0.05 μm or less, particularly preferably 0.03 μm or less, and most preferably 0 μm.

[0066] <Silane coupling agents (SCA)> In the laminate, a layer of a silane coupling agent is preferably present between the transparent, highly heat-resistant film and the inorganic substrate. In the present invention, the silane coupling agent refers to a compound containing 10% by mass or more of silicon (Si). Furthermore, it is preferable that the silane coupling agent has an alkoxy group in its structure. Furthermore, it is desirable that the silane coupling agent does not contain a methyl group. The use of a silane coupling agent layer allows the intermediate layer between the transparent, highly heat-resistant film and the inorganic substrate to be thin, resulting in fewer outgassing components during heating, less elution even in wet processes, and even if elution does occur, it is limited to a trace amount. To improve heat resistance, the silane coupling agent preferably contains a large amount of silicon oxide, and is particularly preferred to be heat-resistant at temperatures around 400°C. The thickness of the silane coupling agent layer is preferably less than 0.2 μm. For use in flexible electronic devices, a thickness of 100 nm or less (0.1 μm or less) is preferred, more preferably 50 nm or less, and even more preferably 10 nm. Conventional fabrication results in a thickness of approximately 0.10 μm or less. In addition, in processes where it is desirable to use as little silane coupling agent as possible, a thickness of 5 nm or less can be used. If it is 1 nm or less, the peel strength may decrease or there may be areas where the agent does not adhere, so a thickness of 1 nm or more is preferable.

[0067] The silane coupling agent in the present invention is not particularly limited, but is preferably one having an amino group or an 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-dimethylbutylidene)propylamine, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3- Glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, p-styryltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, N-(vinylbenzyl)-2-aminoethyl-3-aminopropyltrimethoxysilane hydrochloride, 3-ureidopropyltriethoxysilane, 3-chloropropyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, bis(triethoxysilylpropyl)tetrasulfide, 3-isocyanatopropyltriethoxysilane, tris-(3- trimethoxysilylpropyl) isocyanurate, chloromethylphenethyltrimethoxysilane, chloromethyltrimethoxysilane, etc.Among these, preferred ones 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-dimethylbutylidene)propylamine, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, aminophenyltrimethoxysilane, aminophenethyltrimethoxysilane, aminophenylaminomethylphenethyltrimethoxysilane, etc. When heat resistance is required in the process, those in which the Si and amino groups are linked by an aromatic group are desirable.

[0068] The peel strength between the transparent, highly heat-resistant film and the inorganic substrate must be greater than 0.3 N / cm. This prevents peeling between the transparent, highly heat-resistant film and the inorganic substrate during the process of forming a device on the transparent, highly heat-resistant film. This allows for the manufacture of mass-produced device assemblies, facilitating the manufacture of flexible electronic devices. The peel strength is preferably 1 N / cm or more, more preferably 3 N / cm or more, even more preferably 5 N / cm or more, and particularly preferably 7 N / cm or more. It is also preferably 15 N / cm or less. There is no particular upper limit, but 15 N / cm or less is sufficient for industrial applications, and 12 N / cm or less is acceptable. The peel strength is measured after bonding the transparent, highly heat-resistant film and the inorganic substrate and then heat-treating them in air at 100°C for 10 minutes (initial peel strength). Furthermore, the peel strength of the laminate obtained by measuring the initial peel strength is preferably within the above range even after further heat-treating the laminate at 300°C for 1 hour in a nitrogen atmosphere (peel strength after 300°C heat treatment).

[0069] The laminate of the present invention can be produced, for example, by the following procedure. At least one surface of an inorganic substrate is pre-treated with a silane coupling agent, and a transparent, highly heat-resistant film is superimposed on the silane coupling agent-treated surface. Then, the two are laminated under pressure to obtain a laminate. Alternatively, at least one surface of a transparent, highly heat-resistant film is pre-treated with a silane coupling agent, and the silane coupling agent-treated surface is superimposed on an inorganic substrate. Then, the two are laminated under pressure to obtain a laminate. When the transparent, highly heat-resistant film has a laminate structure of two or more layers, it is preferable to superimpose a first transparent, highly heat-resistant film on the inorganic substrate. Examples of pressurization methods include ordinary pressing or lamination in air or pressing or lamination in vacuum. However, in order to obtain stable peel strength across the entire surface, lamination in air is preferable for large-sized laminates (e.g., over 200 mm). In contrast, pressing in a vacuum is preferable for small-sized laminates of approximately 200 mm or less. A vacuum of approximately 10 Torr or less is sufficient using a conventional oil-sealed rotary pump. The preferred pressure is 1 MPa to 20 MPa, and more preferably 3 MPa to 10 MPa. High pressure may damage the substrate, and low pressure may result in areas of poor adhesion. The preferred temperature is 90°C to 300°C, and more preferably 100°C to 250°C. High temperatures may damage the film, and low temperatures may result in weak adhesion.

[0070] <Fabrication of films with electronic devices (flexible electronic devices)> By using the laminate, a flexible electronic device can be easily produced using existing equipment and processes for manufacturing electronic devices. Specifically, the electronic device can be formed on the transparent, highly heat-resistant film of the laminate, and the transparent, highly heat-resistant film can be peeled off from the laminate, thereby producing a flexible electronic device. In this specification, the term "electronic device" refers to a wiring substrate having a single-sided, double-sided, or multi-layer structure that carries electrical wiring, an electronic circuit including active elements such as transistors and diodes, and passive devices such as resistors, capacitors, and inductors, as well as 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-luminous displays, wireless and wired communication elements, computing elements, memory elements, MEMS elements, solar cells, thin-film transistors, etc.

[0071] In the method for producing a flexible electronic device herein, after a device is formed on the transparent, highly heat-resistant film of the laminate produced by the above-mentioned method, the transparent, highly heat-resistant film is peeled off from the inorganic substrate.

[0072] <Removal of transparent, heat-resistant film with device from inorganic substrate> The method for peeling the device-attached transparent, highly heat-resistant film from the inorganic substrate is not particularly limited, but may include peeling from the edge using tweezers, making an incision in the transparent, highly heat-resistant film, attaching adhesive tape to one side of the incision, and then peeling from the tape, or vacuum-adsorbing one side of the incision in the transparent, highly heat-resistant film and then peeling from that part. If a small curvature occurs at the incision in the transparent, highly heat-resistant film during peeling, stress will be applied to the device in that area, potentially destroying the device. Therefore, peeling with as large a curvature as possible is desirable. For example, it is desirable to peel while winding the film around a roll with a large curvature, or to peel using a machine configured so that a roll with a large curvature is positioned at the peeling area. Methods for making incisions in the transparent, highly heat-resistant film include, but are not limited to, a method of cutting the transparent, highly heat-resistant film with a cutting tool such as a blade, a method of cutting the transparent, highly heat-resistant film by scanning a laser relative to a laminate, a method of cutting the transparent, highly heat-resistant film by scanning a water jet relative to a laminate, and a method of cutting the transparent, highly heat-resistant film while cutting slightly into the glass layer using a semiconductor chip dicing device.For example, when employing the above-mentioned methods, it is also possible to appropriately employ techniques such as superimposing ultrasonic waves on the cutting tool or adding reciprocating or up-and-down motion to improve cutting performance. Another useful method is to attach another reinforcing substrate to the area to be peeled and peel off the reinforcing substrate together. When the flexible electronic device to be peeled off is a backplane of a display device, it is also possible to attach a frontplane of the display device to the inorganic substrate in advance, integrate the two together on the inorganic substrate, and then peel off the two at the same time to obtain a flexible display device. [Example]

[0073] 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 depart from the gist of the invention.

[0074] [Production Example 1 (Production of Polyimide Solution 1)] A reaction vessel equipped with a nitrogen inlet tube, Dean-Stark tube, reflux tube, thermometer, and stirrer was charged with nitrogen gas, and 32.02 parts by weight of 2,2'-ditrifluoromethyl-4,4'-diaminobiphenyl (TFMB) and 230 parts by weight of N,N-dimethylacetamide (DMAc) were added and completely dissolved. Next, 44.42 parts by weight of 4,4'-(2,2-hexafluoroisopropylidene)diphthalic dianhydride (6FDA) was added in portions as a solid (6FDA / TFMB molar ratio = 1.00 / 1.00). The mixture was stirred at room temperature for 24 hours. This yielded a polyamic acid solution (1) with a solids content of 25% by weight and a reduced end content of 1.10 dl / g. Next, 204 parts by mass of DMAc was added to the obtained polyamic acid solution to dilute it to a polyamic acid concentration of 15% by mass, and then 1.3 parts by mass of isoquinoline was added as an imidization accelerator. Next, while stirring the polyamic acid solution, 12.25 parts by mass of acetic anhydride as an imidization agent was slowly added dropwise. After that, stirring was continued for 24 hours to carry out a chemical imidization reaction, and a polyimide solution was obtained. Next, 100 parts by mass of the obtained polyimide solution was transferred to a reaction vessel equipped with a stirring device and a stirrer, and stirred at a speed of 120 rpm. Next, 150 parts by mass of methanol was slowly added dropwise thereto, and precipitation of powdery polyimide was confirmed. The contents of the separable flask were then filtered off by suction filtration and washed with methanol. The filtered polyimide powder was dried in a dryer at 50°C for 24 hours and then at 260°C for an additional 5 hours to obtain the desired polyimide powder. 20 parts by mass of the obtained polyimide powder was dissolved in 80 parts by mass of DMAc, and a dispersion of colloidal silica dispersed in dimethylacetamide ("Snowtex (registered trademark) DMAC-ST-ZL" manufactured by Nissan Chemical Industries, Ltd.) was added as a lubricant so that the silica (lubricant) accounted for 1.4% by mass of the total polymer solids in the polyimide solution, thereby obtaining a uniform polyimide solution 1.

[0075] [Production Example 2 (Production of Polyamic Acid Solution 2)] After the atmosphere in a reaction vessel equipped with a nitrogen inlet tube, reflux condenser, and stirrer was replaced with nitrogen, 32.02 parts by mass of 2,2'-ditrifluoromethyl-4,4'-diaminobiphenyl (TFMB), 279.9 parts by mass of N,N-dimethylacetamide (DMAc), and a dispersion of colloidal silica dispersed in dimethylacetamide as a lubricant (Nissan Chemical Industries, Ltd., Snowtex (registered trademark) DMAC-ST-ZL)) were added and completely dissolved in the polyamic acid solution, so that the silica (lubricant) accounted for 0.4% by mass of the total polymer solids in the polyamic acid solution. Next, 9.81 parts by mass of 1,2,3,4-cyclobutanetetracarboxylic acid dihydrate (CBDA) and 15.51 parts by mass of 4,4'-oxydiphthalic acid dihydrate (ODPA) were added in solid form in portions (molar ratio of CBDA / ODPA / TFMB = 0.50 / 0.50 / 1.00), and the mixture was stirred at room temperature for 24 hours. Thereafter, a polyamic acid solution 2 having a solid content of 17% by mass and a reduced viscosity of 3.60 dl / g was obtained.

[0076] [Production Example 3 (Production of Polyamic Acid Solution 3)] After the atmosphere in a reaction vessel equipped with a nitrogen inlet tube, reflux condenser, and stirrer was replaced with nitrogen, 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), 103.7 parts by mass of N,N-dimethylacetamide (DMAc), and a dispersion of colloidal silica dispersed in dimethylacetamide as a lubricant (Nissan Chemical Industries, Ltd., Snowtex® DMAC-ST-ZL) were added and completely dissolved in a polyamic acid solution so that the silica (lubricant) accounted for 0.4% by mass of the total polymer solids in the polyamic acid solution. Next, 31.02 parts by mass of 4,4'-oxydiphthalic acid dihydrate (ODPA) was added in portions as a solid (molar ratio of ODPA / 4,4-DDS / 3,3-DDS = 1.00 / 0.80 / 0.20), and the mixture was stirred at room temperature for 24 hours. Thereafter, a polyamic acid solution 3 having a solid content of 35% by mass and a reduced viscosity of 0.70 dl / g was obtained.

[0077] [Production Example 4 (Production of Polyamic Acid Solution 4)] After replacing the atmosphere in a reaction vessel equipped with a nitrogen inlet tube, reflux tube, and stirrer with nitrogen, 22.73 parts by weight of 4,4'-diaminobenzanilide (DABAN), 201.1 parts by weight of N,N-dimethylacetamide (DMAc), and a dispersion of colloidal silica dispersed in dimethylacetamide as a lubricant (Nissan Chemical Industries, Ltd. "Snowtex (registered trademark) DMAC-ST-ZL") were added and completely dissolved so that the silica (lubricant) accounted for 0.4% by weight of the total polymer solids in the polyamic acid solution. Then, 19.32 parts by weight of 1,2,3,4-cyclobutanetetracarboxylic acid dihydrate (CBDA) was added in portions as a solid (CBDA / DABAN molar ratio = 0.985 / 1.000), and the mixture was stirred at room temperature for 24 hours. Then, 173.1 parts by weight of DMAc was added to dilute the mixture, yielding a polyamic acid solution 4 with a NV of 10% and a reduced viscosity of 3.10 dl / g.

[0078] [Production Example 5 (Production of Polyamic Acid Solution 5)] After replacing the atmosphere in a reaction vessel equipped with a nitrogen inlet tube, reflux tube, and stirrer with nitrogen, 32.02 parts by weight of 2,2'-ditrifluoromethyl-4,4'-diaminobiphenyl (TFMB), 252.1 parts by weight of N,N-dimethylacetamide (DMAc), and a dispersion of colloidal silica dispersed in dimethylacetamide as a lubricant (Nissan Chemical Industries, Ltd., "Snowtex (registered trademark) DMAC-ST-ZL") were added and completely dissolved so that the silica (lubricant) accounted for 0.4% by weight of the total polymer solids in the polyamic acid solution. Then, 19.61 parts by weight of 1,2,3,4-cyclobutanetetracarboxylic acid dihydrate (CBDA) was added in portions as a solid (CBDA / TFMB molar ratio = 1.00 / 1.00), and the mixture was stirred at room temperature for 24 hours. Then, 165.7 parts by weight of DMAc was added to dilute the mixture, yielding a polyamic acid solution 5 with a NV of 11% and a reduced viscosity of 3.50 dl / g.

[0079] [Production Example 6 (Production of Polyamic Acid Solution 6)] A reaction vessel equipped with a nitrogen inlet tube, reflux condenser, and stirrer was charged with 16.1 parts by weight of 2,2'-ditrifluoromethyl-4,4'-diaminobiphenyl (TFMB), 109 parts by weight of N-methyl-2-pyrrolidone, and a dispersion of colloidal silica in dimethylacetamide (Nissan Chemical Industries, Ltd., Snowtex® DMAC-ST-ZL) as a lubricant, with the silica (lubricant) accounting for 0.4% by weight of the total polymer solids in the polyamic acid solution. After dissolving, 11.2 parts by weight of 1,2,4,5-cyclohexanetetracarboxylic dianhydride (CHDA) was added in portions at room temperature as a solid (CHDA / TFMB molar ratio = 1.00 / 1.00). The mixture was stirred at room temperature for 12 hours. The mixture was then recovered to yield Polyamic Acid Solution 6, with a NV of 20% and a reduced viscosity of 2.10 dL / g.

[0080] [Production Example 7 (Production of Polyamideimide Solution 7)] A reaction vessel equipped with a nitrogen inlet tube, reflux condenser, and stirrer was charged with 17.8 parts by weight of cyclohexanetricarboxylic anhydride (H-TMA), 1.7 parts by weight of terephthalic acid (TPA), and 26.4 parts by weight of o-tolidine diisocyanate (TODI) (molar ratio of H-TMA / TPA / TODI = 0.90 / 0.10 / 1.00), and 0.15 parts by weight of triethylenediamine and a dispersion of colloidal silica dispersed in N,N-dimethylacetamide (DMAc) (Nissan Chemical Industries, Ltd., "Snowtex (registered trademark) DMAC-ST-ZL") as a lubricant were added so that the silica (lubricant) accounted for 0.4% by weight of the total polymer solids in the polyamic acid solution. The mixture was then dissolved in 150 parts by weight of N-methyl-2-pyrrolidone, and the mixture was allowed to react for 8 hours at 80 to 150°C while stirring under a nitrogen stream, yielding a transparent, viscous polyamideimide solution 7. The inherent viscosity of the resulting polyamideimide was 0.8 dl / g.

[0081] [Preparation Example 1] (Preparation of Polyimide Film A1) Polyimide solution 1 obtained in Production Example 1 was applied to the non-slip surface of polyethylene terephthalate film A4100 (manufactured by Toyobo Co., Ltd.) using a comma coater to a final film thickness of 5 μm. Subsequently, polyamic acid solution 4 obtained in Production Example 4 was applied to polyimide solution 1 using a die coater to a final film thickness of 20 μm. This was dried at 110°C for 10 minutes. After drying, the self-supporting polyamic acid film was peeled from the A4100 film that had been used as the support and passed through a pin tenter equipped with a pin sheet. The film edge was inserted into the pins to hold it. The pin sheet spacing was adjusted to prevent the film from breaking and to prevent unnecessary sagging. The film was then heated at 200°C for 3 minutes, 250°C for 3 minutes, and 300°C for 6 minutes to allow the imidization reaction to proceed. Thereafter, the film was cooled to room temperature in 2 minutes, and the portions of the film with poor flatness at both ends were cut off with a slitter. The film was then wound up into a roll to obtain 500 m of polyimide film A1 with a width of 450 mm.

[0082] [Preparation Example 2] (Preparation of Polyimide Film A2) Polyimide solution 1 obtained in Production Example 1 was applied to the non-slip surface of polyethylene terephthalate film A4100 (manufactured by Toyobo Co., Ltd.) using a comma coater so that the final film thickness would be 5 μm. The polyethylene terephthalate film A4100 was passed through a hot air oven and wound up, during which it was dried at 100°C for 10 minutes. After winding, it was set back on the comma coater side, and then polyamic acid solution 4 obtained in Production Example 4 was applied to the dried polyimide solution 1 so that the final film thickness would be 20 μm. This was then dried at 100°C for 10 minutes. The polyamic acid film, which had become self-supporting after drying, was peeled from the support and passed through a pin tenter equipped with a pin sheet. The film edges were held by inserting them into the pins, and the pin sheet spacing was adjusted to prevent the film from breaking and unnecessary sagging. The film was then heated at 200°C for 3 minutes, 250°C for 3 minutes, and 300°C for 6 minutes to allow the imidization reaction to proceed. The film was then cooled to room temperature over 2 minutes, and the poorly flat portions on both ends of the film were cut off with a slitter. The film was then wound up into a roll to obtain 500 m of polyimide film A2 with a width of 450 mm.

[0083] [Preparation Example 3] (Preparation of Polyimide Film A3) The polyimide solution 1 obtained in Production Example 1 was coated onto the non-slip surface of polyethylene terephthalate film A4100 (manufactured by Toyobo Co., Ltd.) using a comma coater to adjust the final film thickness to 5 μm. Subsequently, the polyamic acid solution 4 obtained in Production Example 4 was applied onto the polyimide solution 1 to a final film thickness of 20 μm. The polyimide solution 1 obtained in Production Example 1 was then coated using a comma coater to adjust the final film thickness to 5 μm. This was dried at 90°C to 10°C for 10 minutes. After drying, the self-supporting polyamic acid film was peeled off from the support and passed through a pin tenter equipped with a pin sheet. The film edges were inserted into the pins to hold the film. The pin sheet spacing was adjusted to prevent the film from breaking and to prevent unnecessary sagging. The film was then heated at 200°C for 3 minutes, 250°C for 3 minutes, and 300°C for 6 minutes to allow the imidization reaction to proceed. Thereafter, the film was cooled to room temperature in 2 minutes, and the portions of the film with poor flatness at both ends were cut off with a slitter. The film was then wound up into a roll to obtain 500 m of polyimide film A3 with a width of 450 mm.

[0084] [Preparation Example 4] (Preparation of Polyimide Film A4) A polyimide film A4 was obtained in the same manner as the polyimide film A1 in Production Example 1, except that the final film thickness of the polyimide solution 1 obtained in Production Example 1 was changed to 0.5 μm.

[0085] [Preparation Example 5] (Preparation of Polyimide Film A5) A polyimide film A5 was obtained in the same manner as the polyimide film A1 in Production Example 1, except that the final film thickness of the polyimide solution 1 obtained in Production Example 1 was changed to 20 μm.

[0086] [Preparation Example 6] (Preparation of Polyimide Film B) Polyimide film B was obtained in the same manner as polyimide film A1 in Production Example 1, except that polyimide solution 1 obtained in Production Example 1 was changed to polyamic acid solution 2 obtained in Production Example 2.

[0087] [Preparation Example 7] (Preparation of Polyimide Film C) Polyimide film C was obtained in the same manner as polyimide film A1 in production example 1, except that polyamide solution 4 obtained in production example 4 was replaced with polyamic acid solution 5 obtained in production example 5.

[0088] [Preparation Example 8] (Preparation of Polyimide Film D) Polyamic acid solution 3 obtained in Production Example 3 was applied to the non-slip surface of polyethylene terephthalate film A4100 (manufactured by Toyobo Co., Ltd.) using a comma coater so that the final film thickness would be 5 μm. The polyethylene terephthalate film A4100 was passed through a hot air oven and wound up, during which it was dried at 100°C for 10 minutes. After winding, it was set back on the comma coater side, and then polyamic acid solution 4 obtained in Production Example 4 was applied to the dried product of polyimide solution 1 so that the final film thickness would be 20 μm. This was dried at 100°C for 10 minutes. The polyamic acid film, which had become self-supporting after drying, was peeled from the support and passed through a pin tenter equipped with a pin sheet, with the film edges held by inserting them into the pins. The pin sheet spacing was adjusted to prevent the film from breaking and to prevent unnecessary sagging, and the film was heated at 200°C for 3 minutes, 250°C for 3 minutes, and 300°C for 6 minutes to allow the imidization reaction to proceed. The film was then cooled to room temperature over 2 minutes, and the poorly flat portions on both ends of the film were cut off with a slitter and wound up into a roll, yielding 500 m of polyimide film D with a width of 450 mm. A portion of this polyimide film D was temporarily fixed at the starting edge to the non-slip surface of polyethylene terephthalate film A4100 (manufactured by Toyobo Co., Ltd.) with polyimide adhesive tape, and polyamic acid solution 3 obtained in Production Example 3 was applied to the film using a die coater to a final film thickness of 5 μm. At this time, the polyamic acid solution 3 side of polyimide film D was in contact with the polyethylene terephthalate film A4100, and polyamic acid solution 4 was applied to the side. This was dried at 90°C for 10 minutes. After drying, the polyimide tape was peeled off and the film was separated from the polyethylene terephthalate film A4100. The film was passed through a pin tenter with a pin sheet equipped with pins, and the film edge was gripped by inserting it into the pins. The pin sheet spacing was adjusted to prevent the film from breaking and to prevent unnecessary slack. The film was heated at 200°C for 3 minutes, 250°C for 3 minutes, and 300°C for 6 minutes to allow the imidization reaction to proceed. Thereafter, the film was cooled to room temperature in 2 minutes, and the portions of the film with poor flatness at both ends were cut off with a slitter. The film was then wound up into a roll to obtain 20 m of polyimide film D with a width of 400 mm.

[0089] [Preparation Example 9] (Preparation of Polyimide Film E) Polyimide film E was obtained in the same manner as polyimide film A1 in Production Example 1, except that polyimide solution 1 obtained in Production Example 1 was changed to polyamic acid solution 6 obtained in Production Example 6.

[0090] [Preparation Example 10] (Preparation of Polyimide Film F) Polyimide film F was obtained in the same manner as polyimide film A1 in Production Example 1, except that polyimide solution 1 obtained in Production Example 1 was changed to polyamideimide solution 7 obtained in Production Example 7.

[0091] [Preparation Example 11] (Preparation of Polyimide Film G) Polyimide film G was obtained in the same manner as polyimide film A1 in production example 1, except that polyamide solution 4 obtained in production example 4 was replaced with polyamic acid solution 2 obtained in production example 2.

[0092] [Preparation Example 12] (Preparation of Polyimide Film H) Polyimide film H was obtained in the same manner as polyimide film A1 in Production Example 1, except that polyamide solution 4 obtained in Production Example 4 was changed to polyimide solution 1 obtained in Production Example 1, and polyamic acid solution 1 obtained in Production Example 1 was changed to polyamic acid solution 3 obtained in Production Example 3.

[0093] [Preparation Example 13] (Preparation of Polyimide Film I) Polyimide film I was obtained in the same manner as polyimide film A1 in production example 1, except that polyamide solution 4 obtained in production example 4 was changed to polyamideimide solution 7 obtained in production example 7, and polyimide solution 1 obtained in production example 1 was changed to polyamic acid solution 6 obtained in production example 6.

[0094] [Preparation Example 14] (Preparation of Polyimide Film J) Polyimide film J was obtained in the same manner as polyimide film A1 in production example 1, except that polyamide solution 4 obtained in production example 4 was changed to polyamideimide solution 7 obtained in production example 7, and polyimide solution 1 obtained in production example 1 was changed to polyamic acid solution 2 obtained in production example 2.

[0095] [Preparation Example 15] (Preparation of Polyimide Film K) Polyimide film J was obtained in the same manner as polyimide film A1 in Production Example 1, except that polyimide solution 1 obtained in Production Example 1 was changed to polyamic acid solution 5 obtained in Production Example 5.

[0096] [Preparation Example 16] (Preparation of Polyimide Film L) Polyimide film L was obtained in the same manner as polyimide film A1 in production example 1, except that polyamide solution 4 obtained in production example 4 was changed to polyamic acid solution 6 obtained in production example 6, and polyimide solution 1 obtained in production example 1 was changed to polyamic acid solution 2 obtained in production example 2.

[0097] [Preparation Example 17] (Preparation of Polyimide Film M) A polyimide film M was obtained in the same manner as in the preparation of polyimide film A1 in Preparation Example 1, except that polyamide solution 4 obtained in Preparation Example 4 was changed to polyamic acid solution 2 obtained in Preparation Example 2, and polyimide solution 1 obtained in Preparation Example 1 was changed to polyamic acid solution 4 obtained in Preparation Example 4.

[0098] [Preparation Example 18] (Preparation of Polyimide Film N) Polyimide film N was obtained in the same manner as polyimide film A1 in production example 1, except that polyamide solution 4 obtained in production example 4 was changed to polyamideimide solution 7 obtained in production example 7, and polyimide solution 1 obtained in production example 1 was changed to polyamic acid solution 4 obtained in production example 4.

[0099] [Preparation Example 19] (Preparation of Polyimide Film O) The polyimide solution 1 obtained in Production Example 1 was applied to the non-slip surface of a polyethylene terephthalate film A4100 (manufactured by Toyobo Co., Ltd.) using a die coater to a final film thickness of 20 μm. This was dried at 110 ° C for 10 minutes. After drying, the self-supporting polyimide film was peeled off from the A4100 film that had been used as the support, passed through a pin tenter with a pin sheet, and the film edges were gripped by inserting them into the pins. The pin sheet spacing was adjusted to prevent the film from breaking and to prevent unnecessary slack. The film was then heated at 200 ° C for 3 minutes, 250 ° C for 3 minutes, and 300 ° C for 6 minutes to allow the imidization reaction to proceed. The film was then cooled to room temperature over 2 minutes, and the poorly flat portions of both ends of the film were cut off using a slitter. The film was then wound into a roll to obtain 500 m of polyimide film O with a width of 450 mm.

[0100] [Preparation Examples 20 to 25] (Preparation of Polyimide Films P to U) Polyimide films P to U were obtained in the same manner as for polyimide film O in Production Example 19, except that polyimide solution 1 obtained in Production Example 1 was replaced with polyamic acid solutions 2 to 6 and polyamideimide solution 7 obtained in Production Examples 2 to 7.

[0101] <Polyimide film thickness measurement> The thicknesses of the polyimide films A1 to U were measured using a micrometer (Militron 1245D, manufactured by Fine Rufu Co., Ltd.). The results are shown in Table 1.

[0102] <Tensile modulus, tensile strength at break, and tensile elongation at break of polyimide film> Polyimide films A1 to U were cut into 100 mm x 10 mm strips in the machine direction (MD) and the transverse direction (TD) to prepare test specimens. Using a tensile tester (Shimadzu Corporation, Autograph®, Model AG-5000A), the tensile modulus, tensile strength at break, and tensile elongation at break were measured in both the MD and TD directions at a tension speed of 50 mm / min and a chuck distance of 40 mm. The results are shown in Table 1.

[0103] <Coefficient of linear expansion (CTE) of polyimide film> The polyimide films A1 to U were measured for expansion and contraction in the machine direction (MD) and width direction (TD) under the following conditions. The expansion and contraction ratios were measured at 15°C intervals, such as 30°C to 45°C and 45°C to 60°C. This measurement was continued up to 300°C, and the average of all measurements was calculated as CTE. The results are shown in Table 1. Device name: MAC Science TMA4000S Sample length: 20mm Sample width: 2mm Heating start temperature: 25℃ Heating end temperature: 300℃ Heating rate: 5℃ / min Atmosphere: Argon

[0104] [Table 1]

[0105] Example 1 The silane coupling agent was applied to the glass substrate using the experimental setup shown in Figure 1. Figure 1 is a schematic diagram of the experimental setup used to apply the silane coupling agent to the glass substrate. Glass substrate 1 (0.7 mm thick OA11G glass (NEG) cut to a 100 mm x 100 mm size) was used. Glass substrate 1 was washed with pure water, dried, and then dry-cleaned by irradiating it with a UV / O3 irradiator (SKR1102N-03, LAN Technical) for 1 minute. 150 g of 3-aminopropyltrimethoxysilane (silane coupling agent, Shin-Etsu Chemical KBM903) was placed in a 1 L chemical tank, and the outer water bath was heated to 41 °C. The resulting vapor was then sent to the chamber along with clean, dry air. The gas flow rate was 25 L / min, and the substrate temperature was 38 °C. The clean, dry air temperature was 23 °C, and the humidity was 1.2% RH. The exhaust was connected to a negative pressure exhaust port, and a differential pressure gauge confirmed that the chamber was at a negative pressure of about 10 Pa. The substrates used for the obtained laminate, the SCA coating method, and the SCA coating time are shown in Table 2. Next, polyimide film A1 (70 mm × 70 mm size) was laminated onto the silane coupling agent layer to obtain a laminate. In this case, the laminated surface was the polyimide surface made from polyimide solution 1. For lamination, an MCK laminator was used, and the lamination conditions were compressed air pressure: 0.6 MPa, temperature: 22°C, humidity: 55% RH, and lamination speed: 50 mm / sec. The results of measuring this laminate are shown in Table 2.

[0106] Example 2 A laminate was obtained in the same manner as in Example 1, except for the silane coupling agent application method and inorganic substrate as follows. For this application method, a Si wafer substrate (a dummy-grade 8-inch wafer) cut into 100 mm x 100 mm pieces was placed on a spin coater (Japan Create Co., Ltd., MSC-500S). Isopropyl alcohol (IPA) was dropped onto the glass substrate 1, which was then rotated at 500 rpm to spread the solution over the entire surface of the glass substrate and allowed to dry. A 1% IPA solution of the silane coupling agent 3-aminopropyltrimethoxysilane (Shin-Etsu Chemical KBM903) was then dropped onto the glass and rotated at 2000 rpm to shake off the diluted silane coupling agent and dry it. The rotation was stopped 30 seconds after the drop. As a result, a silane coupling agent layer was formed on the glass substrate. Measurements of this laminate were performed. The substrate used, SCA application method, and SCA application time are shown in Table 2.

[0107] Example 3 A laminate was obtained in the same manner as in Example 1, except that the transparent, highly heat-resistant film used was changed from Film A1 to Film A2. In this case, the bonding surface was the polyimide surface made from Polyimide Solution 1. Measurements of this laminate showed that the substrate used, the SCA application method, and the SCA application time are as shown in Table 2.

[0108] Example 4 A laminate was obtained in the same manner as in Example 1, except that the transparent, highly heat-resistant film used was changed from Film A1 to Film A3. In this case, the bonding surface was the polyimide surface made from Polyimide Solution 1. Measurements of this laminate showed that the substrate used, the SCA application method, and the SCA application time are as shown in Table 2.

[0109] Example 5 A laminate was obtained in the same manner as in Example 1, except that the transparent, highly heat-resistant film used was changed from Film A1 to Film A4. In this case, the bonding surface was the polyimide surface made from Polyimide Solution 1. Measurements of this laminate showed that the substrate used, the SCA application method, and the SCA application time are as shown in Table 2.

[0110] Example 6 A laminate was obtained in the same manner as in Example 2, except that the transparent, highly heat-resistant film used was changed from Film A1 to Film B, and the substrate was changed from a Si wafer to a glass substrate 1. In this case, the bonding surface was a polyimide surface made from Polyamic Acid Solution 2. Measurements of this laminate showed that the substrates used, the SCA application method, and the SCA application time are as shown in Table 2.

[0111] Example 7 A laminate was obtained in the same manner as in Example 1, except that the transparent, highly heat-resistant film used was changed from Film A1 to Film C, and the substrate was changed from Glass Substrate 1 to Glass Substrate 2 (730 × 920 mm). In this case, the bonding surface was the polyimide surface made from Polyimide Solution 1. Measurements of this laminate showed that the substrates used, the SCA application method, and the SCA application time are as shown in Table 2.

[0112] Example 8 A laminate was obtained in the same manner as in Example 1, except that the transparent, highly heat-resistant film used was changed from Film A1 to Film D. In this case, the bonding surface was the polyimide surface made from Polyamic Acid Solution 3. Measurements of this laminate showed that the substrates used and the coating method were as shown in Table 2.

[0113] Example 9 A laminate was obtained in the same manner as in Example 1, except that the transparent, highly heat-resistant film used was changed from Film A1 to Film E, and the substrate was changed from Glass Substrate 1 to Glass Substrate 3 (100 × 100 mm, 30 mm thick). In this case, the bonding surface was a polyimide surface made from Polyamic Acid Solution 6. Measurements of this laminate showed that the substrates used and the coating method are as shown in Table 2.

[0114] Example 10 A laminate was obtained in the same manner as in Example 1, except that the transparent, highly heat-resistant film used was changed from Film A1 to Film F. In this case, the bonding surface was a polyimide surface made from Polyamideimide Solution 7. Measurements of this laminate revealed that the substrates used and the coating method were as shown in Table 2.

[0115] Example 11 A laminate was obtained in the same manner as in Example 1, except that the transparent, highly heat-resistant film used was changed from Film A1 to Film G, and the substrate was changed from Glass Substrate 1 to Si wafer. In this case, the bonding surface was the polyimide surface made from Polyimide Solution 1. Measurements of this laminate showed that the substrates used and the coating method are as shown in Table 2.

[0116] Example 12 A laminate was obtained in the same manner as in Example 1, except that the transparent, highly heat-resistant film used was changed from Film A1 to Film H. In this case, the bonding surface was the polyimide surface made from Polyamic Acid Solution 3. Measurements of this laminate showed that the substrates used and the coating method were as shown in Table 2.

[0117] Example 13 A laminate was obtained in the same manner as in Example 1, except that the transparent, highly heat-resistant film used was changed from Film A1 to Film I. In this case, the bonding surface was the polyimide surface made from Polyamic Acid Solution 2. Measurements of this laminate showed that the substrates used and the coating method were as shown in Table 2.

[0118] Example 14 A laminate was obtained in the same manner as in Example 1, except that the transparent, highly heat-resistant film used was changed from Film A1 to Film J. In this case, the bonding surface was a polyimide surface made from Polyamic Acid Solution 6. Measurements of this laminate showed that the substrates used and the coating method were as shown in Table 2.

[0119] (Comparative Example 1) A laminate was obtained in the same manner as in Example 1, except that the transparent, highly heat-resistant film used was changed from Film A1 to Film A5. In this case, the bonding surface was the polyimide surface made from Polyimide Solution 1. Measurements of this laminate showed that the substrate used, the SCA application method, and the SCA application time are as shown in Table 4.

[0120] (Comparative Example 2) A laminate was obtained in the same manner as in Example 1, except that the transparent, highly heat-resistant film used was changed from Film A1 to Film K. In this case, the bonding surface was a polyimide surface made from Polyamic Acid Solution 5. Measurements of this laminate showed that the substrate used, the SCA application method, and the SCA application time are as shown in Table 4.

[0121] (Comparative Example 3) A laminate was obtained in the same manner as in Example 1, except that the transparent, highly heat-resistant film used was changed from Film A1 to Film L. In this case, the bonding surface was the polyimide surface made from Polyamic Acid Solution 2. Measurements of this laminate showed that the substrate used, the SCA application method, and the SCA application time are as shown in Table 4.

[0122] Comparative Example 4 A laminate was obtained in the same manner as in Example 1, except that the transparent, highly heat-resistant film used was changed from Film A1 to Film M. In this case, the bonding surface was the polyimide surface made from Polyamic Acid Solution 4. Measurements of this laminate revealed that the substrate used, the SCA application method, and the SCA application time are as shown in Table 4.

[0123] (Comparative Example 5) A laminate was obtained in the same manner as in Example 1, except that the transparent, highly heat-resistant film used was changed from Film A1 to Film N. In this case, the bonding surface was the polyimide surface made from Polyamic Acid Solution 4. Measurements of this laminate revealed that the substrate used, the SCA application method, and the SCA application time are as shown in Table 4.

[0124] <Measurement of 90° initial peel strength> The laminate obtained by the above laminate production was heat-treated in the air at 100°C for 10 minutes. Thereafter, the 90° initial peel strength between the inorganic substrate (glass substrate or silicon wafer) and the polyimide film was measured. The results are shown in Tables 2 to 4. The conditions for measuring the 90° initial peel strength are as follows. The film is peeled off at a 90° angle from the inorganic substrate. The measurement is carried out five times and the average value is used as the measurement value. Measuring device: Shimadzu Autograph AG-IS Measurement temperature; room temperature (25℃) Peeling speed: 100mm / min atmosphere; atmosphere Measurement sample width: 2.5cm

[0125] <Measurement of 90° peel strength after heating at 300°C for 1 hour> The laminate obtained by the above laminate production was heat-treated at 100°C for 10 minutes in an air atmosphere. It was then heated at 300°C for 1 hour in a nitrogen atmosphere. Thereafter, the 90° peel strength between the inorganic substrate and the polyimide film was measured. The results are shown in Tables 2 to 4. The measurement conditions for the 90° peel strength after heating at 300°C for 1 hour were the same as those for the initial 90° peel strength.

[0126] <Haze of 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. The same measurement was performed three times, and the arithmetic average value was used. The results are shown in Tables 2 to 4.

[0127] <Total light transmittance of polyimide film> The total light 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. The same measurement was performed three times, and the arithmetic average value was used. The results are shown in Tables 2 to 4.

[0128] <Polyimide film color> The yellow index was measured. The tristimulus values XYZ of the polyimide film were measured using a color meter (ZE6000, manufactured by Nippon Denshoku Co., Ltd.) and a C2 light source in accordance with ASTM D1925, and the yellowness index (YI) was calculated using the following formula. The same measurement was performed three times, and the arithmetic average value was used. YI=100×(1.28X-1.06Z) / Y The results are shown in Tables 2 to 4.

[0129] <Warping of laminates of transparent, heat-resistant films and inorganic substrates> The warpage (%) of a laminate of a transparent, heat-resistant film and an inorganic substrate refers to the degree of deformation in the thickness direction relative to the plane direction of the laminate before and after the specified heat treatment described below. Specifically, as shown in Figure 4, a 100 mm x 100 mm test piece was placed on a surface plate at room temperature so that the test piece was concave, and the average distance from the flat surface of the four corners (h1rt, h2rt, h3rt, h4rt: in mm) was taken as the original warpage (mm). After heat treatment at 300 °C for 1 hour, the test piece was placed on a flat surface so that the test piece was concave, and the average distance from the flat surface of the four corners (h1, h2, h3, h4: in mm) was taken as the warpage (mm). The difference from the original warpage was taken as the warpage at 300 °C. The curl amount is expressed as a percentage (%) of the distance from each vertex to the center (70.7 mm) of the test piece. The measured value is the average of 10 points. However, even if there are not enough laminates to sample 10 points, measurements are still taken on 3 or more sheets. Specifically, it is calculated using the following formula. Original warpage (mm) = (h1rt+h2rt+h3rt+h4rt) / 4 Warpage (mm) = (h1 + h2 + h3 + h4) / 4 Warpage at 300°C (mm) = Warpage - Original warpage Warpage at 300℃ (%) = 100 × (warpage at 300℃) / 70.7 The results are shown in Tables 2 to 4.

[0130] [Table 2]

[0131] [Table 3]

[0132] [Table 4]

[0133] [Production Example 8 (Production of Lubricant-Containing Polyamic Acid Solution 8)] After the atmosphere in a reaction vessel equipped with a nitrogen inlet tube, reflux tube, and stirrer was replaced with nitrogen, 33.36 parts by mass of 2,2'-ditrifluoromethyl-4,4'-diaminobiphenyl (TFMB), 336.31 parts by mass of N-methyl-2-pyrrolidone (NMP), and a dispersion of colloidal silica dispersed in dimethylacetamide as a lubricant (Nissan Chemical Industries, Ltd., "Snowtex (registered trademark) DMAC-ST-ZL") were added and completely dissolved in the polyamic acid solution, so that the silica (lubricant) accounted for 0.3% by mass of the total polymer solids in the polyamic acid solution. Next, 9.81 parts by mass of 1,2,3,4-cyclobutanetetracarboxylic acid dihydrate (CBDA), 11.34 parts by mass of 3,3',4,4'-biphenyltetracarboxylic acid, and 4.85 parts by mass of 4,4'-oxydiphthalic acid dihydrate (ODPA) were added in solid form in portions, and the mixture was stirred at room temperature for 24 hours. Thereafter, a polyamic acid solution 8 (molar ratio of TFMB / / CBDA / BPDA / ODPA=1.00 / / 0.48 / 0.37 / 0.15) having a solid content of 15% by mass and a reduced viscosity of 3.50 dl / g was obtained.

[0134] [Production Example 9 (Production of Lubricant-Free Polyamic Acid Solution 9)] After purging the atmosphere in a reaction vessel equipped with a nitrogen inlet tube, reflux tube, and stirrer with nitrogen, 33.36 parts by weight of 2,2'-ditrifluoromethyl-4,4'-diaminobiphenyl (TFMB) was completely dissolved in 336.31 parts by weight of N-methyl-2-pyrrolidone (NMP). Next, 9.81 parts by weight of 1,2,3,4-cyclobutanetetracarboxylic acid dihydrate (CBDA), 11.34 parts by weight of 3,3',4,4'-biphenyltetracarboxylic acid, and 4.85 parts by weight of 4,4'-oxydiphthalic acid dihydrate (ODPA) were added in solid form in portions and stirred at room temperature for 24 hours. A polyamic acid solution 9 with a solids content of 15% by weight and a reduced viscosity of 3.50 dL / g (TFMB / CBDA / BPDA / ODPA molar ratio = 1.00 / 0.48 / 0.37 / 0.15) was obtained.

[0135] (Example 26) In an atmosphere conditioned to 25°C and 45% RH, polyamic acid solution 8 obtained in Production Example 8 was applied to the non-slip surface of a PET film serving as a temporary support using an apparatus equipped with a roll-to-roll comma coater and a continuous drying oven to a final film thickness of 5 μm, and then, 10 seconds later, polyamic acid solution 9 obtained in Production Example 9 was applied to polyamic acid solution 8 using a die coater to a final film thickness of 20 μm. This was dried at 110°C for 10 minutes. After drying, the self-supporting film was peeled from the PET film support and passed through a pin tenter equipped with a pin sheet. The film edges were inserted into the pins to hold the film. The pin sheet spacing was adjusted to prevent breakage and unnecessary slack. The film was then heated at 200°C for 3 minutes, 250°C for 3 minutes, 300°C for 3 minutes, and 400°C for 3 minutes to promote imidization. The film was then cooled to room temperature over 2 minutes, and any unevenness on both edges was removed using a slitter. The film was then wound into a roll, yielding a 530 mm wide, 80 m long roll of Polyimide Film X. The resulting Polyimide Film X had a total film thickness of 25 μm, a haze of 0.41%, a total light transmittance of 88.2%, a yellow index of 4.1, a breaking strength of 230 MPa, a breaking elongation of 13.1%, a modulus of elasticity of 4.4 GPa, a CTE of 29 ppm / K, and a warp of less than 0.1 mm.

[0136] (Example 27) In an atmosphere conditioned to 25°C and 45% RH, polyamic acid solution 8 obtained in Production Example 8 was applied to the non-slip surface of a PET film serving as a temporary support using an apparatus equipped with a roll-to-roll comma coater and a continuous drying oven so that the final film thickness would be 3 μm. After 10 seconds, polyamic acid solution 9 obtained in Production Example 9 was applied to the polyamic acid solution 8 using a die coater so that the final film thickness would be 19 μm. After a further 30 seconds, polyamic acid solution 8 was applied using another die coater so that the final film thickness would be 3 μm, and the resulting film was dried at 110°C for 10 minutes. After drying, the self-supporting film was peeled off from the PET film support and heated using a pin tenter at 200°C for 3 minutes, 250°C for 3 minutes, 300°C for 3 minutes, and 400°C for 3 minutes, as in Example 12, to allow the imidization reaction to proceed. The same procedure was repeated to obtain a roll of polyimide film Y measuring 530 mm in width and 80 m in length. The resulting polyimide film Y had a three-layer structure consisting of a polyimide obtained from polyamic acid 8 / polyamic acid 9 / polyamic acid 8, and had a total film thickness of 25 μm, a haze of 0.43%, a total light transmittance of 88.1%, a yellow index of 4.1, a breaking strength of 180 MPa, an elongation at break of 12.5%, a modulus of elasticity of 4.2 GPa, a CTE of 30 ppm / K, and a warp of 0.1 mm or less.

[0137] Example 15 Using the polyimide film X obtained in Preparation Example 26 and the surface obtained from polyamic acid solution 8 as the bonding surface, a laminate of a polyimide film and a glass substrate was obtained in the same manner as in Example 1. The obtained laminate had an initial peel strength of 0.45 N / cm, a peel strength after heating to 300°C of 5.2 N / cm, a haze of 0.47%, a haze of 0.55% after heating to 300°C, an initial total light transmittance of 86.5%, a total light transmittance of 84.3% after heating to 300°C, an initial color tone (yellow index) of 4.4, a color tone of 4.8 after heating to 300°C, an initial warp of 80 μm, and a warp of 230 μm after heating to 300°C.

[0138] Example 16 Preparation Example 27 Using the obtained polyimide film Y, the same procedure as in Example 15 was carried out except that the surface to be bonded was the surface to which polyamic acid solution 8 had been last applied, to obtain a polyimide film / glass substrate laminate. The obtained laminate had an initial peel strength of 0.43 N / cm, a peel strength after heating to 300°C of 5.0 N / cm, a haze of 0.46%, a haze of 0.56% after heating to 300°C, an initial total light transmittance of 86.3%, a total light transmittance of 83.4% after heating to 300°C, an initial color tone (yellow index) of 4.5, a color tone of 4.9 after heating to 300°C, an initial warp of 50 μm, and a warp of 120 μm after heating to 300°C. [Explanation of symbols]

[0139] 1 flow meter 2 Gas inlet 3 Chemical tank (silane coupling agent tank) 4. Hot water bath (bathwater bath) 5. Heater 6 Processing chamber 7 Base material 8 exhaust port 11 First transparent, highly heat-resistant film layer 12 Second transparent, heat-resistant film layer 13 Silane coupling agent layer 14 Inorganic Substrates 15 Electronic Devices 16 Film with electronic devices 17 Laminate 18 Surface Plate

Claims

1. In a laminate of a transparent, highly heat-resistant film and an inorganic substrate without using an adhesive, The adhesive has a Si (silicon) component of less than 10% by mass, and the thickness of the adhesive layer is 0.4 μm or less, The transparent, highly heat-resistant film has a laminated structure of two or more layers, a first transparent, high heat resistant film layer in contact with the inorganic substrate, comprising the structure of Formula 1, 【Chemical 1】 (In formula 1, R 1 represents one or more selected from the group consisting of structures of formula 2, formula 3, formula 4, and formula 5. In formulas 2 to 5, * represents a bond to each imide group.) 【Chemistry 2】 【Chemistry 3】 【Chemistry 4】 【Chemistry 5】 the peel strength between the heat-resistant film and the inorganic substrate is greater than 0.3 N / cm, and the amount of warping of the laminate after heating at 300°C is 1400 μm or less; A laminate characterized by being used for forming an electronic device on the transparent, highly heat-resistant film.

2. 2. The laminate according to claim 1, wherein the first transparent, highly heat-resistant film layer in contact with the inorganic substrate has a CTE of 20 ppm / K or more by itself.

3. 3. The laminate according to claim 1, wherein the transparent, highly heat-resistant film has a CTE of 40 ppm / K or less.

4. 4. The laminate according to claim 1, wherein the first transparent, highly heat-resistant film layer in contact with the inorganic substrate is made of a transparent polyimide.

5. 5. The laminate according to claim 1, wherein at least one of the second transparent, highly heat-resistant film layers that is not in contact with the inorganic substrate is made of a transparent polyimide.

6. 6. The laminate according to claim 1, wherein the inorganic substrate has a long side of 300 mm or more.

7. A method for producing a film with an electronic device, comprising forming an electronic device on the transparent, highly heat-resistant film according to any one of claims 1 to 6, and then peeling it off from the inorganic substrate.

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