Stacked body and method for manufacturing flexible device

Abstract

Provided is a laminate in which the surface of an inorganic substrate is smooth after a high heat-resistant film is peeled from the laminate of the inorganic substrate and the high heat-resistant film, and the inorganic substrate can be reused. A first laminate, which is a first laminate of a first high heat-resistant film and an inorganic substrate substantially without using an adhesive, has the following (1) to (4). (1) The tensile elastic modulus of the first high heat-resistant film is 4 GPa or greater; (2) the adhesive strength of the first high heat-resistant film to the inorganic substrate is 0.3 N / cm or less; (3) the surface roughness Ra of the contact surface of the first high heat-resistant film to the inorganic substrate is 5 nm or less; and (4) the surface roughness Ra of the surface of the inorganic substrate after the first high heat-resistant film is peeled from the first laminate is 3 nm or less.

Description

Fabrication methods of laminates and flexible devices Technical Field

[0001] This invention relates to a laminate containing a high heat-resistant film such as a polyimide resin formed on an inorganic substrate, and a method for manufacturing a flexible device. The laminate of this invention is useful, for example, in manufacturing flexible devices and flexible circuit boards in which electronic components are formed on the surface of a flexible substrate. Background Technology

[0002] In the past, in the fields of flat panel displays (FPDs) such as liquid crystal displays (LCDs), plasma display panels (PDPs), and organic OLED displays (OLEDs), as well as electronic devices such as electronic paper, electronic components were mainly formed on substrates made of inorganic materials such as glass substrates (inorganic substrates). However, because inorganic substrates are rigid and lack flexibility, they have the problem of being difficult to make flexible.

[0003] Therefore, a method has been proposed to use flexible and heat-resistant organic polymer materials such as polyimide as substrates. Specifically, a flexible, heat-resistant film is laminated onto an inorganic substrate used as a carrier, and this heat-resistant film is used as a substrate or circuit board for forming electronic components; this technique has been put into practical use. Here, for example, if a glass substrate with excellent light transmittance is used as the inorganic substrate, not only are the inspection processes during the formation of electronic components and the fabrication of circuit boards simplified, but it also has the advantage of being able to directly utilize existing flexible equipment for forming electronic components on glass substrates.

[0004] In inorganic substrates with a flexible substrate composed of such a high heat-resistant film, since the inorganic substrate is used as a carrier substrate, after electronic components are formed on the surface of the high heat-resistant film, the high heat-resistant film must eventually be peeled off from the inorganic substrate. Therefore, good peelability after the electronic components are formed is required.

[0005] As an industrial method for peeling a high heat-resistant film firmly attached to an inorganic substrate from the substrate, methods have been proposed, such as laser irradiation at the interface of the high heat-resistant film, such as polyimide resin in contact with the glass substrate (Patent Document 1), Joule heating of the interface of the polyimide film in contact with the glass substrate (Patent Document 2), induction heating (Patent Document 3), and irradiation with a xenon lamp flash (Patent Document 4). However, these methods are not only complex and time-consuming, with expensive equipment, but also present the problem of difficulty in recycling the inorganic substrate.

[0006] Here, a method is proposed that uses a silane coupling agent to bond an inorganic substrate and a high heat-resistant film with relatively weak force, making it easy to peel off from the inorganic substrate (Patent Document 5).

[0007] Existing technical documents

[0008] Patent documents

[0009] [Patent Document 1] Japanese Patent Publication No. 2007-512568

[0010] [Patent Document 2] Japanese Patent Application Publication No. 2012-189974

[0011] [Patent Document 3] Japanese Patent Application Publication No. 2014-86451

[0012] [Patent Document 4] Japanese Patent Application Publication No. 2014-120664

[0013] [Patent Document 5] Japanese Patent Application Publication No. 2014-100722 Summary of the Invention

[0014] The problem the invention aims to solve

[0015] The method disclosed in Patent Document 5 results in a smooth surface on the inorganic substrate after the high heat-resistant film is peeled off, making it easy to reuse. However, in the method using silane coupling agents, if the elastic modulus of the high heat-resistant film is low, the high heat-resistant film deforms / breaks at the peeling interface during peeling from the inorganic substrate, resulting in an uneven surface on the inorganic substrate after peeling off the high heat-resistant film, making it difficult to reuse.

[0016] Therefore, the present invention solves the above-mentioned problems and aims to provide a laminate in which the surface of the inorganic substrate is very smooth after the high heat-resistant film is peeled off from the laminate of the inorganic substrate and the high heat-resistant film, and the inorganic substrate can be reused.

[0017] Technical solutions to the problem

[0018] In order to solve the above-mentioned problems, the inventors conducted in-depth research and found that if the high heat-resistant film stacked on the inorganic substrate has a specific elastic modulus, the peel strength between the inorganic substrate and the heat-resistant resin film is below a certain value, which can solve the above-mentioned problems and realize the present invention.

[0019] That is, the present invention comprises the following components.

[0020] [1] A first laminate, which is a first laminate of a first high heat-resistant film and an inorganic substrate that is substantially adhesive-free, has the following features (1) to (4):

[0021] (1) The tensile elastic modulus of the first high heat-resistant film is above 4 GPa.

[0022] (2) The adhesion strength between the first high heat-resistant film and the inorganic substrate is less than 0.3 N / cm.

[0023] (3) The surface roughness Ra of the contact surface between the first high heat-resistant film and the inorganic substrate is less than 5 nm.

[0024] (4) The surface roughness Ra of the inorganic substrate after the first high heat-resistant film is peeled off from the first layer is less than 3 nm.

[0025] [2][1] The laminated body further has the following (5) characteristics:

[0026] (5) The nitrogen content of the bonding surface between the inorganic substrate and the first high heat-resistant film is more than 0.2 atomic% and less than 12 atomic%.

[0027] The first laminate as described in [3][1] or [2], wherein the CTE of the first high heat-resistant film is below 50 ppm / K.

[0028] [4] A method for manufacturing a second laminate, comprising:

[0029] (a) The process of peeling the first high heat-resistant film from the first laminate as described in any one of [1] to [3] to obtain an inorganic substrate,

[0030] (b) A process of laminating a second high heat-resistant film on the surface of the inorganic substrate over which the first high heat-resistant film is laminated to obtain a second laminate.

[0031] The second layer has the following characteristics (6) to (9):

[0032] (6) The tensile elastic modulus of the second high heat-resistant film is above 4 GPa.

[0033] (7) The adhesion strength between the second high heat-resistant film and the inorganic substrate is less than 0.3 N / cm.

[0034] (8) The surface roughness Ra of the contact surface between the second high heat-resistant film and the inorganic substrate is less than 5 nm.

[0035] (9) The surface roughness Ra of the inorganic substrate after the second high heat-resistant film is peeled off from the second layer is less than 3 nm.

[0036] The manufacturing method of the second laminate described in [5][4] further comprises the following feature (10):

[0037] (10) The nitrogen content of the bonding surface between the inorganic substrate and the second high heat-resistant film is more than 0.2 atomic% and less than 12 atomic%.

[0038] The manufacturing method of the second laminate as described in [6][4] or [5], wherein the CTE of the second high heat-resistant film is less than 50 ppm / K.

[0039] [7] A method for manufacturing a flexible electronic device, characterized in that, after obtaining the second laminate as described in any one of claims 4 to 6, it has the following steps: (c) forming electronic components or circuits on the surface of the second high heat-resistant film, and then peeling off the inorganic substrate.

[0040] The effects of the invention

[0041] In the laminate and the manufacturing method of the laminate of the present invention, the high heat-resistant film can be easily peeled off from the inorganic substrate, and since the surface of the inorganic substrate after peeling off the high heat-resistant film is sufficiently smooth, the inorganic substrate can be reused repeatedly. Attached Figure Description

[0042] [Figure 1] A schematic diagram showing an example of a silane coupling agent coating apparatus according to one embodiment of the present invention.

[0043] Symbol Explanation

[0044] 1. Flow meter

[0045] 2 Gas inlet

[0046] 3. Chemical liquid tank (silane coupling agent tank)

[0047] 4. Warm water bath (water bath heating)

[0048] 5 heaters

[0049] 6. Processing Chamber (Room)

[0050] 7. Substrate

[0051] 8. Exhaust port Detailed Implementation

[0052] Hereinafter, embodiments of the present invention will be described.

[0053] High heat-resistant film

[0054] The high heat-resistant film in this invention, unless otherwise specified, refers to the collective term for the first high heat-resistant film and the second high heat-resistant film. The first and second high heat-resistant films can be films of the same composition or films of different compositions. Preferably, they are films of the same composition. Furthermore, the high heat-resistant film has a single-layer or multi-layer structure (laminated structure), and from the perspective of physical strength and ease of peeling from the inorganic substrate, a multi-layer structure with two or more layers is preferred. When the high heat-resistant film has a multi-layer structure, the number of layers can be two or more, preferably three or more. Furthermore, it is preferably 10 layers or less, more preferably 5 layers or less. Additionally, when having a multi-layer structure, each layer can be a film layer of the same composition or a film layer of different compositions. Preferably, they are film layers of the same composition. Furthermore, it is preferable that it has a symmetrical structure in the thickness direction.

[0055] The high heat-resistant film preferably has a melting point of 250°C or higher, more preferably 300°C or higher, and even more preferably 400°C or higher. Furthermore, it is preferably made of a polymer with a glass transition temperature of 200°C or higher, more preferably 320°C or higher, and even more preferably 380°C or higher. Hereinafter, for the sake of simplicity, it will be referred to as a polymer. In this specification, the melting point and glass transition temperature are obtained by differential calorimetry (DSC). It should be noted that when the melting point is greater than 500°C, it is best to visually observe the thermal deformation behavior when heated at that temperature to determine whether the melting point has been reached. Additionally, when the high heat-resistant film has a multilayer structure, the measurement value refers to the entire high heat-resistant film (all layers).

[0056] Examples of high heat-resistant films (hereinafter also simply referred to as polymer films) include polyimide resins such as polyimide, polyamide-imide, polyether-imide, and fluorinated polyimide (e.g., aromatic polyimide resins and alicyclic polyimide resins); copolyesters such as polyethylene, polypropylene, polyethylene terephthalate, polyethylene terephthalate, and polyethylene 2,6-naphthalenedicarboxylate (e.g., fully aromatic polyesters and semi-aromatic polyesters); copoly(meth)acrylates represented by polymethyl methacrylate; polycarbonate; polyamide; polysulfone; polyethersulfone; polyetherketone; cellulose acetate; cellulose nitrate; aromatic polyamide; polyvinyl chloride; polyphenols; polyarylates; polyacetals; modified polyphenylene ether; polyphenylene sulfide; polyphenylene ether; polystyrene; polybenzoxazole; polybenzothiazole; polybenzimidazole; cyclic polyolefins; liquid crystal polymers, etc. Alternatively, examples can be given of materials reinforced with glass fillers, glass fibers, etc.

[0057] However, since the polymer membrane is designed for use in processes involving heat treatment at temperatures above 250°C, the types of polymer membranes that can be practically used are limited. Preferably, the polymer membrane is made of so-called super engineering plastics; more specifically, examples include aromatic polyimide membranes, alicyclic polyimide membranes, aromatic amide membranes, aromatic amide-imide membranes, amide-imide membranes, aromatic benzoxazole membranes, aromatic benzothiazole membranes, aromatic benzimidazole membranes, cyclic polyolefins, liquid crystal polymers, etc.

[0058] Typically, polyamide-imide films are obtained by coating a polyamide-imide solution, obtained by reacting diisocyanates and tricarboxylic acids in a solvent, onto a support for making polyamide-imide films, drying it to form a polyamide-imide film containing, for example, 1 to 50% by mass of solvent, and further drying the polyamide-imide film containing 1 to 50% by mass of solvent at high temperature while it is on or peeled off from the support for making polyamide-imide films.

[0059] In addition, polyamide films are typically obtained by coating a polyamide solution obtained by reacting diamines and dicarboxylic acids in a solvent onto a support for making polyamide films, drying it to form a polyamide film containing, for example, 1 to 50% by mass of solvent, and then further drying the polyamide film containing 1 to 50% by mass of solvent at high temperature on the polyamide support or in a state peeled off from the support.

[0060] <Polyimide film>

[0061] The following is a detailed description of an example of a polyimide-based resin film (sometimes also called a polyimide film). Typically, a polyimide-based resin film is obtained by coating a polyamic acid (polyimide precursor) solution, obtained by reacting diamines and tetracarboxylic acids in a solvent, onto a support for making a polyimide film, drying it to form a green film (hereinafter referred to as a "precursor film" or "polyamic acid film"), and further subjecting the green film to a high-temperature heat treatment at room temperature, either on the support for making the polyimide film or in a state peeled off from the support, to a dehydration and ring-closing reaction. Here, a green film refers to a self-supporting polyamic acid film containing a solvent. The solvent content of the green film is not particularly limited as long as it possesses self-supporting properties, but is preferably 1% by mass or more, more preferably 5% by mass or more, further preferably 10% by mass or more, even more preferably 20% by mass or more, and particularly preferably 30% by mass or more. Additionally, it is preferably 80% by mass or less, more preferably 70% by mass or less, further preferably 60% by mass or less, and particularly preferably 50% by mass or less.

[0062] Coating of polyamic acid (polyimide precursor) solutions can be performed using various known solution coating methods, such as spin coating, blade coating, applicator coating, comma coating machine, screen printing, slot coating, reverse coating, dip coating, curtain coating, and slot die coating. Because methods for preparing films using polyamic acid solutions offer a wide range of material choices and readily available, easily peelable materials are readily available for research. However, the imidization reaction must be carefully controlled. In contrast, the preparation of films without imidization reactions is easier and therefore should be used appropriately.

[0063] In this invention, the polyimide film is a polymer film with imide bonds on its main chain, preferably a polyimide film or a polyamide-imide film, and more preferably a polyimide film. Additionally, a polyamide film is also preferred.

[0064] Typically, as described above, a polyimide film is obtained by coating a polyamic acid (polyimide precursor) solution, obtained by reacting a diamine and a tetracarboxylic acid in a solvent, onto a support for making a polyimide film, drying it to form a green film, and then further subjecting the green film to a high-temperature heat treatment to undergo a dehydration and ring-closure reaction on or peeled from the support. Alternatively, as another method, a polyimide solution obtained by performing a dehydration and ring-closure reaction of a diamine and a tetracarboxylic acid in a solvent is coated onto a support for making a polyimide film, dried to form a polyimide film, for example, containing 1 to 50% by mass of solvent, and then further subjecting the polyimide film containing 1 to 50% by mass of solvent to a high-temperature heat treatment to dry it.

[0065] There are no particular limitations on the diamines that constitute polyamic acid; aromatic diamines, aliphatic diamines, and alicyclic diamines commonly used in polyimide synthesis can be used. From the viewpoint of heat resistance, aromatic diamines are preferred. Diamines can be used alone or in combination of two or more.

[0066] Diamines are not particularly limited; for example, diphenylamine (bis(4-aminophenyl) ether) and p-phenylenediamine (1,4-phenylenediamine) can be cited.

[0067] As the tetracarboxylic acids constituting polyamic acids, aromatic tetracarboxylic acids (including their anhydrides), aliphatic tetracarboxylic acids (including their anhydrides), and alicyclic tetracarboxylic acids (including their anhydrides) commonly used in the synthesis of polyimides can be used. When these are anhydrides, the molecule can have one or two anhydride structures, preferably substances with two anhydride structures (dianhydrides). Tetracarboxylic acids can be used alone or in combination of two or more.

[0068] As a tetracarboxylic acid, there are no particular limitations; for example, pyromellitic dianhydride and 3,3',4,4'-biphenyltetracarboxylic dianhydride can be cited.

[0069] An example of the high heat-resistant film of the present invention, a transparent high heat-resistant film, will be described. The transparent polyimide film will be described in detail. Regarding the transparency of the transparent polyimide, a total light transmittance of 75% or more is preferred. More preferably, it is 80% or more, further preferably 85% or more, even more preferably 87% or more, and particularly preferably 88% or more. The upper limit of the total light transmittance of the transparent high heat-resistant film is not particularly limited, but for use in flexible electronic devices, it is preferably 98% or less, more preferably 97% or less.

[0070] To obtain a colorless and highly transparent polyimide, this invention uses aromatic tetracarboxylic acids, such as 4,4′-(2,2-hexafluoroisopropyl)diphthalic acid, 4,4′-oxydiphthalic acid, bis(1,3-dioxane-1,3-dihydro-2-benzofuran-5-carboxylic acid)1,4-phenylene, bis(1,3-dioxane-1,3-dihydro-2-benzofuran-5-yl)phenyl-1,4-dicarboxylic acid, 4,4′-[4,4′-(3-oxane-1,3-dihydro-2-benzofuran-1,1-diyl)bis(phenyl-1,4-diyloxy)]diphenyl-1,2-dicarboxylic acid, 3,3′, 4,4′-benzophenone tetracarboxylic acid, and 4,4′-[(3-oxane-1,3-dioxane-1,3-diyloxy)]diphenyl-1,2-dicarboxylic acid. [H-2-benzofuran-1,1-diyl)bis(toluene-2,5-dioxy)]diphenyl-1,2-dicarboxylic acid, 4,4′-[(3-oxoylide-1,3-dihydro-2-benzofuran-1,1-diyl)bis(1,4-xylene-2,5-dioxy)]diphenyl-1,2-dicarboxylic acid, 4,4′-[4,4′-(3-oxoylide-1,3-dihydro-2-benzofuran-1,1-diyl)bis(4-isopropyl-toluene-2,5-dioxy)]diphenyl-1,2-dicarboxylic acid, 4,4′-[4,4′-(3-oxoylide-1,3-dihydro-2-benzofuran-1,1-diyl)bis(naphthalene-1,4-dioxy)]diphenyl-1,2-dicarboxylic acid, 4,4′-[4 4′-(3H-2,1-benzoxathiol)-1,1-dioxide-3,3-diyl)bis(benzyl-1,4-diyloxy)]diphenyl-1,2-dicarboxylic acid, 4,4′-benzophenone tetracarboxylic acid, 4,4′-[(3H-2,1-benzoxathiol)-1,1-dioxide-3,3-diyl)bis(toluene-2,5-diyloxy)]diphenyl-1,2-dicarboxylic acid, 4,4′-[(3H-2,1-benzoxathiol)-1,1-dioxide-3,3-diyl)bis(1,4-xylene-2,5-diyloxy)]diphenyl-1,2-dicarboxylic acid, 4,4′-[4,4′- ... ,1-dioxide-3,3-diyl)bis(4-isopropyl-toluene-2,5-diyloxy)]diphenyl-1,2-dicarboxylic acid, 4,4′-[4,4′-(3H-2,1-benzoxylthiapentane-1,1-dioxide-3,3-diyl)bis(naphthalene-1,4-diyloxy)]diphenyl-1,2-dicarboxylic acid, 3,3′,4,4′-benzophenone tetracarboxylic acid, 3,3′,4,4′-benzophenone tetracarboxylic acid, 3,3′,4,4′-diphenylsulfone tetracarboxylic acid, 3,3′,4,4′-biphenyltetracarboxylic acid, 2,3,3′,4′-biphenyltetracarboxylic acid, pyromellitic acid, 4,4′-[spiro(xanthan-9,9′-fluorene)-2,6-diylbis(oxycarbonyl)]diphthalic acid, 4,Tetracarboxylic acids such as 4′-[spiro(xanthon-9,9′-fluorene)-3,6-dimethylbis(oxycarbonyl)]diphthalic acid and their anhydrides. Among these, dianhydrides having two anhydride structures are suitable, particularly preferably 4,4'-(2,2-hexafluoroisopropylidene)phthalic acid dianhydride and 4,4'-oxyphthalic acid dianhydride dianhydrous. Furthermore, aromatic tetracarboxylic acids can be used alone or in combination of two or more. Where heat resistance is important, for example, it is preferable that the total amount of aromatic tetracarboxylic acids is 50% by mass or more, more preferably 60% by mass or more, further preferably 70% by mass or more, even more preferably 80% by mass or more, particularly preferably 90% by mass or more, and 100% by mass is also acceptable.

[0071] Examples of alicyclic tetracarboxylic acids include 1,2,3,4-cyclobutanetetracarboxylic acid, 1,2,3,4-cyclopentanetetracarboxylic acid, 1,2,3,4-cyclohexanetetracarboxylic acid, 1,2,4,5-cyclohexanetetracarboxylic acid, 3,3′,4,4′-bicyclohexyltetracarboxylic acid, bicyclo[2,2,1]heptane-2,3,5,6-tetracarboxylic acid, bicyclo[2,2,2]octane-2,3,5,6-tetracarboxylic acid, bicyclo[2,2,2]oct-7-enyl-2,3,5,6-tetracarboxylic acid, tetrahydroanthracene-2,3,6,7-tetracarboxylic acid, tetratetrahydro-1,4:5,8:9,10-trimethanoanthracene-2,3,6,7-tetracarboxylic acid, and decahydronaphthalene-2,3,6... 7-Tetracarboxylic acid, decahydro-1,4:5,8-dimethanonaphthalene-2,3,6,7-tetracarboxylic acid, decahydro-1,4-ethionophthalene-2,3,6,7-tetracarboxylic acid, norbornane-2-spiro-α-cyclopentanone-α′-spiro-2″-norbornane-5,5″,6,6″-tetracarboxylic acid (also known as "norbornane-2-spiro-2′-cyclopentanone-5′-spiro-2″-norbornane-5,5″,6,6″-tetracarboxylic acid"), methylnorbornane-2-spiro-α-cyclopentanone-α′-spiro-2″-(methylnorbornane)-5,5″,6,6″-tetracarboxylic acid, norbornane-2 -spiro-α-cyclohexanone-α′-spiro-2″-norbornane-5,5″,6,6″-tetracarboxylic acid (also known as "norbornane-2-spiro-2′-cyclohexanone-6-spiro-2″-norbornane-5,5″,6,6″-tetracarboxylic acid"), methylnorbornane-2-spiro-α-cyclohexanone-α′-spiro-2″-(methylnorbornane)-5,5″,6,6″-tetracarboxylic acid, norbornane-2-spiro-α-cyclopropanone-α′-spiro-2″-norbornane-5,5″,6,6″-tetracarboxylic acid, norbornane-2-spiro-α-cyclobutanone-α′-spiro-2″-norbornane-5,5″,6,6″-tetracarboxylic acid, norbornane-2-spiro-α-cycloheptanone-α′-spiro-2″-norbornane-5,5″,6,6″-tetracarboxylic acid, norbornane-2-spiro-α-cycloheptanone-α′-spiro-2″-norbornane-5,5″,6,6″-tetracarboxylic acid, norbornane-2-spiro-α-cycloheptanone-α′-spiro-2″-norbornane-5,5″,6,6″-tetracarboxylic acid, 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-cyclodecanoone-α′-spiro-2″-norbornane-5,5″,6,6″-tetracarboxylic acid, norbornane-2-spiro-α-cycloundecanone-α′-spiro-2″-norbornane-5,5″,6,6″-tetracarboxylic acid, norbornane-2-spiro-α-cyclododecanone-α′-spiro-2″-norbornane-5,5″,6,6″-tetracarboxylic acid, norbornane-2-spiro-α-cyclododecanone-α′-spiro-2″-norbornane-5,5″,6,6″-tetracarboxylic acid, norbornane-2-spiro-α-cyclotridecanone-α′-spiro-2″-norbornane-5,5″, 6, 6″-tetracarboxylic acid, norbornane-2-spiro-α-cyclotetradecanoone-α′-spiro-2″-norbornane-5, 5″, 6, 6″-tetracarboxylic acid, norbornane-2-spiro-α-cyclopentadecanone-α′-spiro-2″-norbornane-5, 5″, 6, 6″-tetracarboxylic acid, norbornane-2-spiro-α-(methylcyclopentanone)-α′-spiro-2″-norbornane-5, 5″, 6, 6″-tetracarboxylic acid, norbornane-2-spiro-α-(methylcyclohexanone)-α′-spiro-2″-norbornane-5, 5″, 6, 6″-tetracarboxylic acid, and other tetracarboxylic acids, as well as their anhydrides. Among these, dianhydrides having two anhydride structures are preferred, particularly 1,2,3,4-cyclobutanetetracarboxylic acid dianhydrides, 1,2,3,4-cyclohexanetetracarboxylic acid dianhydrides, and 1,2,4,5-cyclohexanetetracarboxylic acid dianhydrides, more preferably 1,2,3,4-cyclobutanetetracarboxylic acid dianhydrides and 1,2,4,5-cyclohexanetetracarboxylic acid dianhydrides, and even more preferably 1,2,3,4-cyclobutanetetracarboxylic acid dianhydrides. It should be noted that these can be used alone or in combination of two or more. The copolymerization amount of the alicyclic tetracarboxylic acid is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, still more preferably 80% by mass or more, particularly preferably 90% by mass or more, and 100% by mass is also acceptable, provided transparency is important.

[0072] Examples of tricarboxylic acids include aromatic tricarboxylic acids such as trimellitic acid, 1,2,5-naphthalenetricarboxylic acid, diphenyl ether-3,3′,4′-tricarboxylic acid, and diphenyl sulfone-3,3′,4′-tricarboxylic acid, or hydrides of the aforementioned aromatic tricarboxylic acids such as hexahydrotriphenylcarboxylic acid; alkylene glycol trimellitic acid esters such as ethylene glycol dipreptyl trimellitate, propylene glycol dipreptyl trimellitate, 1,4-butanediol dipreptyl trimellitate, and polyethylene glycol dipreptyl trimellitate; and their monohydric anhydrides and esterifications. Among these, monohydric anhydrides having one anhydride structure are preferred, and in particular, trimellitic acid tricarboxylic anhydride and hexahydrotriphenylcarboxylic anhydride are preferred. Furthermore, these can be used alone or in combination.

[0073] Examples of dicarboxylic acids include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, and 4,4′-oxydibenzoic acid, or hydrides of the aforementioned aromatic dicarboxylic acids such as 1,6-cyclohexanedicarboxylic acid; oxalic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, octanoic acid, azelaic acid, sebacic acid, undecanoic acid, dodecanoic acid, 2-methylsuccinic acid, and their acyl chlorides or esters. Among these, aromatic dicarboxylic acids and their hydrides are preferred, especially terephthalic acid, 1,6-cyclohexanedicarboxylic acid, and 4,4′-oxydibenzoic acid. Furthermore, dicarboxylic acids can be used alone or in combination.

[0074] In this invention, there are no particular limitations on the diamines or isocyanates used to obtain colorless and highly transparent polyimides. Aromatic diamines, aliphatic diamines, alicyclic diamines, aromatic diisocyanates, aliphatic diisocyanates, and alicyclic diisocyanates commonly used in polyimide synthesis, polyamide-imide synthesis, and polyamide synthesis can be used. From the viewpoint of heat resistance, aromatic diamines are preferred, and from the viewpoint of transparency, alicyclic diamines are preferred. Furthermore, if an aromatic diamine with a benzoxazole structure is used, it exhibits high heat resistance, high elastic modulus, low thermal shrinkage, and a low coefficient of linear expansion. Diamines and isocyanates can be used alone or in combination of two or more.

[0075] 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, bis[4-(3-aminophenoxy)phenyl]sulfide, bis[4-(3-aminophenoxy)phenyl]sulfone, 2,2-bis[4-(3-aminophenoxy)phenyl]propane, and 2,2-bis[4-(3-aminophenoxy)phenyl]-1,1, 1,3,3,3-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′-diaminodiphenyl sulfone Benzene, 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]propane [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)-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 [phenoxy)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]diphenyl sulfone, bis[4-{4-(4-aminophenoxy)phenoxy}phenyl]sulfone, 1,4-bis[4-(4-aminophenoxy)phenoxy-α,α-dimethylbenzyl]benzene, 1,3-bis[4-(4-aminophenoxy)phenoxy-α,α-dimethylbenzyl]benzene, 1,3-bis[4-(4-aminophenoxy)phenoxy-α,α-dimethylbenzyl]benzene, 1,3-bis[4-(4-amino-6-trifluoromethylphenoxy) ... [4-(4-amino-6-methylphenoxy)-α,α-dimethylbenzyl]benzene, 1,3-bis[4-(4-amino-6-methylphenoxy)-α,α-dimethylbenzyl]benzene, 1,3-bis[4-(4-amino-6-cyanophenoxy)-α,α-dimethylbenzyl]benzene, 3,3′-diamino-4,4′-diphenoxybenzophenone, 4,4′-diamino-5,5′-diphenoxybenzophenone, 3,4′-diamino-4,5′-diphenoxybenzophenone, 3,3′-diamino-4-phenoxybenzophenone, 4,4′-diamino-5-phenoxybenzophenone, 3,4′-diamino-4-phenoxybenzophenone, 3,4′-diamino-5′-phenoxybenzophenone, 3,3′-diamino-4-phenoxybenzophenone4′-Diphenyloxybenzophenone, 4,4′-diamino-5,5′-diphenyloxybenzophenone, 3,4′-diamino-4,5′-diphenyloxybenzophenone, 3,3′-diamino-4-biphenyloxybenzophenone, 4,4′-diamino-5-biphenyloxybenzophenone, 3,4′-diamino-4-biphenyloxybenzophenone, 3,4′-diamino-5′-biphenyloxybenzophenone, 1,3-bis(3-amino-4-phenoxybenzoyl)benzene, 1,4-bis(3-amino-4-phenoxybenzoyl)benzene, 1,3-bis(4-amino-5-phenoxybenzoyl)benzene, 1,4-bis(4-amino-5-phenoxybenzoyl)benzene, 1,3-bis(3-amino-4-biphenyloxybenzoyl)benzene 1,4-bis(3-amino-4-biphenoxybenzoyl)benzene, 1,3-bis(4-amino-5-biphenoxybenzoyl)benzene, 1,4-bis(4-amino-5-biphenoxybenzoyl)benzene, 2,6-bis[4-(4-amino-α,α-dimethylbenzyl)phenoxy]benzylnitrile, 4,4′-[9H-fluorene-9,9-diyl]bisaniline (Also known as 9,9-bis(4-aminophenyl)fluorene), spiro(xanthon-9,9′-fluorene)-2,6-diylbis(oxycarbonyl)]bisaniline, 4,4′-[spiro(xanthon-9,9′-fluorene)-2,6-diylbis(oxycarbonyl)]bisaniline, 4,4′-[spiro(xanthon-9,9′-fluorene)-3,6-diylbis(oxycarbonyl)]bisaniline, etc. Furthermore, some or all of the hydrogen atoms on the aromatic ring of the above-mentioned aromatic diamines may be replaced by halogen atoms, alkyl or alkoxy groups having 1 to 3 carbon atoms, or cyano groups. Further, some or all of the hydrogen atoms in the alkyl or alkoxy groups having 1 to 3 carbon atoms may also be replaced by halogen atoms. Furthermore, there are no particular limitations on aromatic diamines having the benzoxazole structure, for example, 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-aminobenzoxazole)-4-(6-aminobenzoxazole)benzene, and 2,6-(4,4′-diaminodiphenyl) Benzo[1,2-d:5,4-d′]bisoxazole, 2,6-(4,4′-diaminodiphenyl)benzo[1,2-d:4,5-d′]bisoxazole, 2,6-(3,4′-diaminodiphenyl)benzo[1,2-d:5,4-d′]bisoxazole, 2,6-(3,4′-diaminodiphenyl)benzo[1,2-d:4,5-d′]bisoxazole, 2,6-(3,3′-diaminodiphenyl)benzo[1,2-d:5,4-d′]bisoxazole, 2,6-(3,3′-diaminodiphenyl)benzo[1,2-d:4,[5-d′] Bisoxazole, etc. Among these, 2,2′-bis(trifluoromethyl)-4,4′-diaminobiphenyl, 4-amino-N-(4-aminophenyl)benzamide, 4,4′-diaminodiphenyl sulfone, and 3,3′-diaminobenzophenone are particularly preferred. Furthermore, aromatic diamines can be used alone or in combination.

[0076] Examples of alicyclic diamines include 1,4-cyclohexanediamine, 1,4-diamino-2-methylcyclohexane, 1,4-diamino-2-ethylcyclohexane, 1,4-diamino-2-n-propylcyclohexane, 1,4-diamino-2-isopropylcyclohexane, 1,4-diamino-2-n-butylcyclohexane, 1,4-diamino-2-isobutylcyclohexane, 1,4-diamino-2-sec-butylcyclohexane, 1,4-diamino-2-tert-butylcyclohexane, and 4,4′-methylenebis(2,6-dimethylcyclohexylamine). Among these, 1,4-cyclohexanediamine and 1,4-diamino-2-methylcyclohexane are particularly preferred, and 1,4-cyclohexanediamine is more preferred. Furthermore, alicyclic diamines can be used alone or in combination.

[0077] Examples of diisocyanates include, for instance, diphenylmethane-2,4′-diisocyanate, 3,2′- or 3,3′- or 4,2′- or 4,3′- or 5,2′- or 5,3′- or 6,2′- or 6,3′-dimethyldiphenylmethane-2,4′-diisocyanate, and 3,2′- or 3,3′- or 4,2′- or 4,3′- or 5,2′- or 5,3′- or 6,2′- or 6,3′-diethyldiphenylmethane. -2,4′-diisocyanate, 3,2′- or 3,3′- or 4,2′- or 4,3′- or 5,2′- or 5,3′- or 6,2′- or 6,3′-dimethoxydiphenylmethane-2,4′-diisocyanate, diphenylmethane-4,4′-diisocyanate, diphenylmethane-3,3′-diisocyanate, diphenylmethane-3,4′-diisocyanate, diphenyl ether-4,4′-diisocyanate, benzophenone-4,4′- Diisocyanates, diphenyl sulfone-4, 4′-diisocyanates, toluene-2,4-diisocyanate, toluene-2,6-diisocyanate, m-xylene diisocyanate, p-xylene diisocyanate, naphthalene-2,6-diisocyanate, 4,4′-(2,2-bis(4-phenoxyphenyl)propane)diisocyanate, 3,3'- or 2,2'-dimethylbiphenyl-4,4′-diisocyanate, 3,3'- or 2,2'-diethylbiphenyl- Aromatic diisocyanates such as 4,4′-diisocyanate, 3,3′-dimethoxybiphenyl-4,4′-diisocyanate, and 3,3′-diethoxybiphenyl-4,4′-diisocyanate, as well as hydrogenated diisocyanates selected from these (e.g., isophorone diisocyanate, 1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, 4,4′-dicyclohexylmethane diisocyanate, hexamethylene diisocyanate), etc. Among these, considering low hygroscopicity, dimensional stability, price, and polymerizability, diphenylmethane-4,4′-diisocyanate, toluene-2,4-diisocyanate, toluene-2,6-diisocyanate, 3,3′-dimethylbiphenyl-4,4′-diisocyanate, naphthalene-2,6-diisocyanate, 4,4′-dicyclohexylmethane diisocyanate, and 1,4-cyclohexane diisocyanate are preferred. Furthermore, diisocyanates can be used alone or in combination.

[0078] The high heat-resistant film of this invention can be a single-layer structure or a multi-layer (stacked) structure with two or more layers. When the high heat-resistant film is a single-layer structure, the physical properties of the high heat-resistant film (tensile elastic modulus, melting point, glass transition temperature, yellowness index, total transmittance, haze, CTE, etc.) refer to the overall values ​​of the high heat-resistant film. When the high heat-resistant film has a multi-layer structure, the tensile elastic modulus and surface roughness Ra of the high heat-resistant film refer only to the values ​​of the single layer in contact with the inorganic substrate, while other physical properties (melting point, glass transition temperature, yellowness index, total transmittance, haze, CTE, etc.) refer to the overall values ​​of the high heat-resistant film. Therefore, there are no restrictions on the tensile elastic modulus and surface roughness Ra of the layers that do not contact the inorganic substrate (all layers other than the inorganic substrate contact layer).

[0079] When the high heat-resistant film is a transparent high heat-resistant film, its yellowness index (hereinafter also referred to as "yellowness index" or "YI") is preferably 10 or less, more preferably 7 or less, further preferably 5 or less, and even more preferably 3 or less. The lower limit of the yellowness index of the transparent high heat-resistant film is not particularly limited, but for use in flexible electronic devices, it is preferably 0.1 or more, more preferably 0.2 or more, and even more preferably 0.3 or more.

[0080] In this invention, the transmittance of the transparent high heat-resistant film at a wavelength of 400 nm is preferably 70% or more, more preferably 72% or more, further preferably 75% or more, and even more preferably 80% or more. There is no particular upper limit to the transmittance of the transparent high heat-resistant film at a wavelength of 400 nm, but for use in flexible electronic devices, it is preferably 99% or less, more preferably 98% or less, and even more preferably 97% or less.

[0081] In this invention, the haze of the transparent high heat-resistant film is preferably below 1.0, more preferably below 0.8, further preferably below 0.5, and even more preferably below 0.3. The lower limit is not particularly limited; industrially, a haze of 0.01 or higher is acceptable, and 0.05 or higher is also permissible.

[0082] It should be noted that the polyimide film with a low coefficient of linear expansion (CTE) as described in this invention can also be achieved by stretching the polyimide film during its formation process. This stretching operation is achieved by coating a polyimide solution onto a support for making the polyimide film, drying it to form a polyimide film containing 1-50% by mass of solvent, and then further stretching the polyimide film containing 1-50% by mass of solvent at high temperature during drying, either on or peeled from the support, at a ratio of 1.5 to 4.0 times in the MD direction and 1.4 to 3.0 times in the TD direction. In this case, by using an unstretched thermoplastic polymer film as the support for making the polyimide film, and simultaneously stretching both the thermoplastic polymer film and the polyimide film, and then peeling the stretched polyimide film off the thermoplastic polymer film, damage to the polyimide film, especially during stretching in the MD direction, can be prevented, resulting in a higher-grade polyimide film.

[0083] The average coefficient of linear expansion (CTE) of the high heat-resistant film between 30°C and 250°C is preferably 50 ppm / K or less. More preferably, it is 45 ppm / K or less, further preferably 40 ppm / K or less, even more preferably 30 ppm / K or less, and particularly preferably 20 ppm / K or less. Additionally, it is preferably -5 ppm / K or more, more preferably -3 ppm / K or more, and even more preferably 1 ppm / K or more. If the CTE is within this range, the difference between the CTE and the coefficient of linear expansion of a typical support (inorganic substrate) can be ensured to be small, allowing the high heat-resistant film and the inorganic substrate to be peeled off even in processes involving heating, and preventing warping of each support. Here, CTE represents the reversible expansion and contraction factor with respect to temperature. It should be noted that the CTE of the high heat-resistant film refers to the average value of the CTE in the mechanical direction (MD direction) and the CTE in the width direction (TD direction). The method for measuring the CTE of the high heat-resistant film is the method described in the examples.

[0084] Furthermore, when the high heat-resistant film has a stacked structure of two or more layers, the difference in CTE between each individual layer can cause warping, which is not preferable. Therefore, the difference in CTE between the high heat-resistant film layer in contact with the inorganic substrate and the high heat-resistant film layer adjacent to the high heat-resistant film layer that is not in contact with 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. Among the layers constituting the high heat-resistant film stack, the thickest layer is preferably within this range. In addition, if the high heat-resistant film has a symmetrical structure along the film thickness direction, warping is less likely to occur, which is also preferable.

[0085] When the transparent high-heat-resistant film has a laminated structure of two or more layers, the transparent high-heat-resistant film layer in contact with the inorganic substrate preferably contains polyimide having a structure of Formula 1 and / or Formula 2. The total amount of polyimide having the structures of Formula 1 and Formula 2 in the transparent high-heat-resistant film layer is preferably 70% by mass or more, more preferably 80% by mass or more, further preferably 90% by mass or more, particularly preferably 95% by mass or more, and 100% by mass is also acceptable. By containing polyimide having the structures of Formula 1 and / or Formula 2 within the aforementioned range, the transparent high-heat-resistant film can exhibit excellent CTE (Coefficient of Thermal Expansion).

[0086]

Chemistry 1

[0087]

[0088]

Chemistry 2

[0089]

[0090] The thickness of the high heat-resistant film in this invention is preferably 5 μm or more, more preferably 8 μm or more, further preferably 15 μm or more, and even more preferably 20 μm or more. There is no particular upper limit to the thickness of the high heat-resistant film, but for use in flexible electronic devices, it is preferably 200 μm or less, more preferably 150 μm or less, and even more preferably 90 μm or less. If it is too thin, film manufacturing and conveying become difficult; if it is too thick, conveying using rollers or the like becomes difficult.

[0091] The tensile modulus of elasticity of the high heat-resistant film must be 4 GPa or higher. Preferably, it is 5 GPa or higher, and more preferably 6 GPa or higher. There is no particular upper limit to the tensile modulus of elasticity, but it is approximately 15 GPa. If the tensile modulus of elasticity is below 15 GPa, the high heat-resistant film can be used as a flexible film. If the tensile modulus of elasticity is 4 GPa or higher, the high heat-resistant film peels off well from the inorganic substrate, allowing for smooth peeling and suppressing unevenness on the surface of the inorganic substrate. When the high heat-resistant film has a multilayer structure, the tensile modulus of elasticity of the single layer in contact with the inorganic substrate must be 4 GPa. The physical properties of the single layer in contact with the inorganic substrate can be evaluated by manufacturing a single layer of film with the same composition as the layer in contact with the inorganic substrate and determining its tensile modulus of elasticity. The film-making method for the single layer can be any of the manufacturing examples described in the embodiments. The method for determining the tensile modulus of elasticity of the high heat-resistant film is the method described in the embodiments.

[0092] The thickness non-uniformity of the high heat-resistant film is preferably 20% or less, more preferably 12% or less, further preferably 7% or less, and particularly preferably 4% or less. If the thickness non-uniformity is greater than 20%, it tends to become difficult to apply to narrow sections. It should be noted that the thickness non-uniformity of the high heat-resistant film is determined, for example, by measuring the film thickness at approximately 10 randomly selected locations on the film being measured using a contact-type film thickness gauge, based on the following formula.

[0093] Membrane thickness non-uniformity (%)

[0094] =100×(maximum film thickness-minimum film thickness)÷average film thickness

[0095] The high heat-resistant film is preferably obtained in a rolled form as a strip with a width of 300 mm or more and a length of 10 m or more, and more preferably as a roll of high heat-resistant film wound around a core. The high heat-resistant film is easier to transport when wound into a roll.

[0096] In order to ensure operability and productivity, it is preferable to add or make the high heat-resistant film contain about 0.03 to 3% by mass of lubricant (particles) with a particle size of 10 to 1000 nm, so as to give the high heat-resistant film a slight unevenness on the surface and ensure sliding performance.

[0097] In this invention, the transparent high-heat-resistant film is preferably a multilayer structure consisting of two or more layers. By forming a two-layer film with different materials (resins), it is possible to create films possessing various properties. Furthermore, by stacking the layers in a symmetrical structure along the thickness direction (e.g., transparent high-heat-resistant film layer A / transparent high-heat-resistant film layer B / transparent high-heat-resistant film layer A), the overall CTE balance of the film becomes well-balanced, making it difficult for warping to occur. In addition, by making any one layer an ultraviolet and infrared absorption layer, it is possible to give it the characteristic of spectral dispersion, and by using layers with different refractive indices, the incident and emitted light can be controlled.

[0098] As a means of producing a film consisting of two or more layers, various methods can be considered, such as simultaneous coating with a T-die that can simultaneously eject two layers, sequential coating by coating one layer and then coating the next, coating one layer and drying it before coating the next, coating the next layer after the film formation of one layer is completed, or multilayering by adding a thermoplastic layer and heat laminating. In this patent, various existing coating methods and multilayering techniques can be appropriately selected.

[0099] When using a multilayer transparent high-heat-resistant film, the thickness of the first transparent high-heat-resistant film in contact with the inorganic substrate is preferably 0.02 μm or more, more preferably 0.05 μm or more. By reducing the thickness of the first transparent high-heat-resistant film, warping of the entire film can be suppressed. Furthermore, from the viewpoint of making the transparent high-heat-resistant film thinner overall, it is preferably 10 μm or less, more preferably 8 μm or less, and even more preferably 5 μm or less.

[0100] In this invention, the surface roughness Ra of the surface of the high heat-resistant film in contact with the inorganic substrate must be 5 nm or less. Preferably, it is 4.5 nm or less, and more preferably 4 nm or less. By making the surface roughness Ra 5 nm or less, the contact area with the smooth inorganic substrate is increased, resulting in better adhesion. Furthermore, peeling from the first and / or second laminate becomes easier, allowing the inorganic substrate to be reused. There is no particular limitation on the lower limit; for use in flexible electronic devices, 0.01 nm or more is acceptable, and 0.1 nm or more is also fine. It should be noted that the surface roughness Ra of the high heat-resistant film is necessary for its value before being laminated onto the inorganic substrate, and more preferably, it remains within the stated range after peeling from the laminate.

[0101] <Inorganic substrate>

[0102] As the inorganic substrate, any plate-shaped material that can be used as a substrate made of inorganic materials can be used. Examples include articles with glass plates, ceramic plates, semiconductor wafers, metals, etc. as the main body, as well as substrates formed by stacking these glass plates, ceramic plates, semiconductor wafers, and metals as composites, substrates in which these materials are dispersed, substrates containing these fibers, etc.

[0103] The glass plates used include quartz glass, high-silicate glass (96% silica), soda-lime glass, lead glass, aluminoborosilicate glass, borosilicate glass (Pyrex, a registered trademark), borosilicate glass (alkali-free), borosilicate glass (micro-plates), and aluminosilicate glass. Among these, glass with a coefficient of linear expansion of 5 ppm / K or less is ideal. For commercially available products, Corning Gorilla Glass's "Corning 7059," "Coming 1737," and "EAGLE," Asahi Glass's "AN100," Nippon Electric Glass's "OA10" and "OA11," and SCHOTT's "AF32" are particularly suitable for liquid crystal displays.

[0104] The semiconductor wafer is not particularly limited, and examples include silicon wafers, germanium wafers, silicon-germanium wafers, gallium-arsenic wafers, aluminum-gallium-indium wafers, nitrogen-phosphorus-arsenic-antimony wafers, SiC, InP (indium phosphide), InGaAs, GaInNAs, LT, LN, ZnO (zinc oxide), CdTe (cadmium telluride), and ZnSe (zinc selenide). Among these, silicon wafers are preferred, and mirror-polished silicon wafers with a size of 8 inches or larger are particularly preferred.

[0105] The metals mentioned include single-element metals such as W, Mo, Pt, Fe, Ni, and Au; alloys such as Inconel, Monel, Nimonic, carbon copper, Fe-Ni Invar alloy, and super Invar alloy. Additionally, multilayer metal plates formed by adding other metal or ceramic layers to the aforementioned metals are also included. In this case, if the overall CTE of the added layers is low, Cu, Al, etc., can also be used as the main metal layer. There are no limitations on the metal used as the added metal layer, as long as it has strong adhesion to the polymer film and possesses properties such as non-diffusion, chemical resistance, and good heat resistance; suitable examples include Cr, Ni, TiN, and Mo-containing Cu.

[0106] The ceramic plate in this invention includes substrate ceramics 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.

[0107] The inorganic substrate of this invention can be reused after being adhered to and peeled off with a high heat-resistant film. Substrates with a previously adhered high heat-resistant film will retain components from the film. Specifically, on the inorganic substrate after peeling off the polyimide film, the nitrogen content from ESCA is preferably 0.2 atomic% to 12 atomic% or less. If the nitrogen content from ESCA is less than 0.2 atomic%, it can be considered substantially unused glass. Therefore, the nitrogen content is preferably 0.5 atomic% or more, more preferably 0.8 atomic% or more, and even more preferably 1 atomic% or more. Furthermore, if the nitrogen content is greater than 12 atomic%, the amount of residual polyimide on the inorganic substrate is excessive, resulting in an uneven surface on the substrate, which will not exhibit peel strength even when adhered to a smooth polyimide film. Therefore, the nitrogen content is preferably 11.5 atomic% or less, more preferably 11 atomic% or less, and even more preferably 10 atomic% or less.

[0108] The planar portion of the inorganic substrate must be sufficiently flat. Specifically, the surface roughness Ra value of the inorganic substrate after peeling off the high heat-resistant film must be 3 nm or less. Preferably, it is 2.5 nm or less, more preferably 2.1 nm or less. By ensuring that the surface roughness Ra after peeling off the high heat-resistant film is 3 nm or less, the surface smoothness of the inorganic substrate can be maintained, making it reusable. That is, the first high heat-resistant film can be peeled off from the first laminate, and then the second high heat-resistant film can be appropriately laminated. There is no particular limitation on the lower limit; 0.1 nm or more is acceptable for use in flexible electronic devices, and 0.5 nm or more is also acceptable. Furthermore, it is preferable that the surface roughness of the laminate after peeling off the second polymer film (flexible electronic device) from the second laminate is also within the above range. By being within the above range, further reuse is possible. The surface roughness of the inorganic substrate is acceptable as long as at least a portion of the location where the high heat-resistant film is laminated is within the above range, more preferably the entire portion where the high heat-resistant film is laminated is within the above range.

[0109] The thickness of the inorganic substrate is not particularly limited, but from a usability point of view, a thickness of 10 mm or less is preferred, more preferably 3 mm or less, and even more preferably 1.3 mm or less. There is no particular limitation on 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 is prone to breakage, making handling difficult. Conversely, if it is too thick, various handling methods become difficult.

[0110] <Layered Body>

[0111] The laminate of the present invention is formed by substantially laminating the high heat-resistant film and the inorganic substrate without the use of an adhesive. When the high heat-resistant film has a laminated structure of two or more layers, it preferably includes a high heat-resistant film in contact with the inorganic substrate and a high heat-resistant film layer adjacent to the high heat-resistant film layer but not in contact with the inorganic substrate. It should be noted that the laminate in the present invention refers to the collective term for the first laminate and the second laminate. The first laminate refers to the laminate of the first high heat-resistant film and the inorganic substrate, and the second laminate refers to the laminate of the second high heat-resistant film and the inorganic substrate (including the inorganic substrate after the first high heat-resistant film has been peeled off from the first laminate).

[0112] The second laminate can be obtained by (a) peeling the first high heat-resistant film from the first laminate to obtain an inorganic substrate, and (b) laminating the second high heat-resistant film on the surface of the inorganic substrate over which the first high heat-resistant film is laminated.

[0113] There are no particular limitations on the method for peeling the high-heat-resistant film from the laminate. Methods include using tweezers or similar tools to roll it up from the end, making a cut in the high-heat-resistant film, applying adhesive tape to one side of the cut, and then rolling it up from that tape area; or vacuum-adheding one side of the cut of the high-heat-resistant film and then rolling it up from that area. It should be noted that if a small bend occurs at the cut of the high-heat-resistant film during peeling, stress will be applied to the equipment in that area, potentially damaging the equipment. Therefore, peeling with a large curvature is preferable. For example, it is preferable to roll it up while using a roller with a large curvature, or to use a machine configured to place a roller with a large curvature on the peeling section.

[0114] Methods for cutting the high heat-resistant film include cutting the film with a cutting tool such as a blade, cutting the film by relative scanning of a laser and a laminate, cutting the film by relative scanning of a water jet and a laminate, and cutting the film by gradually cutting into several glass layers using a semiconductor chip cutting device. There are no particular limitations on the method. For example, when using the above methods, techniques such as adding ultrasonic waves to the cutting tool, applying back-and-forth motion, and up-and-down motion can be appropriately used to improve cutting performance.

[0115] Alternatively, it is also useful to pre-attach other reinforcing substrates to the peeled-off portion and then peel off the entire reinforcing substrate.

[0116] The shape of the laminate is not particularly limited; it can be square or rectangular. A rectangle is preferred, with the longest side preferably 300 mm or more, more preferably 500 mm or more, and even more preferably 1000 mm or more. There is no particular upper limit; industrially, 20,000 mm or less is acceptable, and 10,000 mm or less is also fine.

[0117] <Adhesive>

[0118] In this invention, there is substantially no adhesive layer between the inorganic substrate and the high heat-resistant film. Here, the adhesive layer referred to in this invention means a layer with a Si (silicon) content of less than 10% by mass. Furthermore, "substantially not used" (not present) means that the thickness of the adhesive layer between the inorganic substrate and the high heat-resistant film is preferably 0.4 μm or less, more preferably 0.3 μm or less, further preferably 0.2 μm or less, particularly preferably 0.1 μm or less, and most preferably 0 μm.

[0119] <Silane Coupling Agent (SCA)>

[0120] In the laminate, a silane coupling agent layer is preferably present between the high heat-resistant film and the inorganic substrate. In this invention, the silane coupling agent refers to a compound containing 10% by mass or more of Si (silicon). By using the silane coupling agent layer, the interlayer between the high heat-resistant film and the inorganic substrate can be thinned, reducing degassing during heating and making it difficult to dissolve even in wet processes; even if dissolution occurs, it is only in trace amounts. To improve heat resistance, the silane coupling agent preferably contains a higher proportion of silicon oxide, and particularly preferably has heat resistance at around 400°C. The thickness of the silane coupling agent layer is preferably less than 0.2 μm. As a range for use in flexible electronic devices, it is preferably 100 nm or less (0.1 μm or less), more preferably 50 nm or less, and even more preferably 10 nm. Typically, it is around 0.10 μm or less during manufacturing. Furthermore, in processes where it is preferable to minimize the amount of silane coupling agent, a thickness of 5 nm or less can also be used. Since a thickness of 1 nm or less may result in reduced peel strength or unattached portions, a thickness of 1 nm or more is preferred.

[0121] In this invention, the silane coupling agent is not particularly limited, but preferably contains amino or epoxy groups. 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-... (3,4-Epoxycyclohexyl)ethyltrimethoxysilane, 3-epoxypropoxypropyltrimethoxysilane, 3-epoxypropoxypropylmethyldiethoxysilane, 3-epoxypropoxypropyltriethoxysilane, vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-epoxypropoxypropyltrimethoxysilane, 3-epoxypropoxypropylmethyldiethoxysilane, 3-epoxypropoxypropyltriethoxysilane, p-styryltrimethoxysilane, 3-methacryloyloxypropylmethyldimethoxysilane, 3-methacryloyloxypropyltrimethoxysilane, 3-methacryloyloxypropylmethyldiethoxysilane, 3-methacryloyloxypropyltriethoxysilane, 3-acryloyloxypropyltrimethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, N-(vinylbenzyl)-2-amino 3-aminopropyltrimethoxysilane hydrochloride, 3-ureopropyltriethoxysilane, 3-chloropropyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, bis(triethoxysilylpropyl)tetrasulfide, 3-isocyanate propyltriethoxysilane, tri-(3-trimethoxysilylpropyl)isocyanurate, chloromethylphenylethyltrimethoxysilane, chloromethyltrimethoxysilane, etc. Among these, preferred options 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-epoxypropoxypropyltrimethoxysilane, 3-epoxypropoxypropylmethyldiethoxysilane, 3-epoxypropoxypropyltriethoxysilane, aminophenyltrimethoxysilane, aminophenylethyltrimethoxysilane, and aminophenylaminomethylphenylethyltrimethoxysilane. When heat resistance is required in the process, coupling agents in which Si and amino groups are linked by an aromatic group are preferred.

[0122] The adhesive strength between the high heat-resistant film and the inorganic substrate needs to be 0.3 N / cm or less. This makes peeling off the high heat-resistant film and the inorganic substrate very easy after the device is formed on the high heat-resistant film. Therefore, it is possible to manufacture device connectors that can be mass-produced, and the manufacture of flexible electronic devices becomes easier. The adhesive strength is preferably 0.25 N / cm or less, more preferably 0.2 N / cm or less, further preferably 0.15 N / cm or less, and particularly preferably 0.1 N / cm or less. It is also preferably 0.01 N / cm or more. For the angle at which the laminate will not peel off when the device is formed on the high heat-resistant film, it is more preferably 0.02 N / cm or more, further preferably 0.03 N / cm or more, and particularly preferably 0.05 N / cm or more. The adhesive strength refers to the value of the laminate after heat treatment at 100°C for 10 minutes in an atmospheric atmosphere (initial adhesive strength) after the high heat-resistant film and the inorganic substrate are bonded. Furthermore, in the laminate from which the initial adhesive strength was measured, after further heat treatment at 300°C for 1 hour in a nitrogen atmosphere, the adhesive strength is also preferably within the range described above (adhesive strength after heat treatment at 300°C).

[0123] The laminate of the present invention can be manufactured, for example, by the following process. First, at least one side of an inorganic substrate is treated with a silane coupling agent. The silane coupling agent-treated side is then overlapped with a high heat-resistant film, and the two are laminated under pressure to obtain a laminate. Alternatively, at least one side of a high heat-resistant film is first treated with a silane coupling agent. The silane coupling agent-treated side is then overlapped with an inorganic substrate, and the two are laminated under pressure to obtain a laminate. As a method of applying pressure, examples include pressing or laminating in the atmosphere or pressing or laminating in a vacuum. For large-sized laminates (e.g., greater than 200 mm) to obtain overall stable adhesive strength, atmospheric lamination is preferred. In contrast, for small-sized laminates of about 200 mm or less, vacuum pressing is preferred. A conventional oil rotary pump can be used, with a vacuum level of about 10 Torr or less. A preferred pressure is 1 MPa to 20 MPa, more preferably 3 MPa to 10 MPa. If the pressure is too high, the substrate may be damaged; if the pressure is too low, some areas may not adhere properly. The preferred temperature is 90°C to 300°C, more preferably 100°C to 250°C. If the temperature is too high, it will damage the film; if the temperature is too low, the adhesion will be weak.

[0124] Fabrication of Flexible Electronic Devices

[0125] If the aforementioned laminate is used, flexible electronic devices can be easily manufactured using existing equipment and processes for manufacturing electronic devices. Specifically, electronic components or circuits (electronic devices) can be formed on the high heat-resistant film of (c) the laminate, and flexible electronic devices can be manufactured by peeling off the high heat-resistant film from the laminate.

[0126] In this specification, electronic equipment refers to circuit boards with single-sided, double-sided, or multi-layer structures that have load electrical circuits, including electronic circuits with active components such as transistors and diodes or passive devices such as resistors, capacitors, and inductors, as well as sensor elements that sense pressure, temperature, light, humidity, etc., biosensor elements, image display elements such as light-emitting elements, liquid crystal displays, electrophoretic displays, and self-emissive displays, wireless and wired communication elements, computing elements, storage elements, MEMS elements, solar cells, thin-film transistors, etc.

[0127] In the manufacturing method of the flexible electronic device of the present invention, after the device is formed on the high heat-resistant film of the laminate produced by the above method, the high heat-resistant film is peeled off from the inorganic substrate.

[0128] <Peeling the high heat-resistant film attached to the device from an inorganic substrate>

[0129] There are no particular limitations on the method for peeling the high-heat-resistant film with attached equipment from an inorganic substrate. Methods include using tweezers or similar tools to roll it up from the end, making a cut in the high-heat-resistant film, applying adhesive tape to one side of the cut, and then rolling it up from that tape section, or vacuum-adheding one side of the cut section of the high-heat-resistant film and then rolling it up from that section. It should be noted that if a small bend occurs at the cut section of the high-heat-resistant film during peeling, stress will be applied to the equipment in that area, potentially damaging the equipment. Therefore, peeling with a large curvature is preferable. For example, it is preferable to roll it up while using a roller with a large curvature, or to use a machine that places a roller with a large curvature on the peeling section for winding.

[0130] Methods for cutting the high heat-resistant film include cutting the film with a cutting tool such as a knife, cutting the film by relative scanning of a laser and a laminate, cutting the film by relative scanning of a water jet and a laminate, and cutting the film by gradually cutting several glass layers using a semiconductor chip cutting device. There are no particular limitations on the method. For example, when using the above methods, techniques such as adding ultrasonic waves to the cutting tool, applying back-and-forth motion, and up-and-down motion can be appropriately used to improve cutting performance.

[0131] Alternatively, pre-attaching other reinforcing substrates to the peeled-off portion and then peeling off the entire reinforcing substrate is also useful. When the peeled-off flexible electronic device is the back panel of a display device, first attaching the front plane of the display device, integrating it onto the inorganic substrate, and then peeling both off simultaneously can also yield a flexible display device.

[0132]

Example

[0133] 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 exceed the spirit of the present invention.

[0134] The following four types of polyimide films were used in the sale of the products.

[0135] F1: Upilex (registered trademark) 25S (polyimide film manufactured by Ube Industries, Ltd., 25μm thick)

[0136] F2: XENOMAX (registered trademark) F38LR2 (polyimide film manufactured by Toyobo Co., Ltd., thickness 38μm)

[0137] F7: A membrane made by plasma treatment of KAPTON (registered trademark) 100H / V (polyimide membrane manufactured by Toray-DuPont Corporation, 25μm thick).

[0138] F9: A membrane formed by plasma treatment of F2.

[0139] Vacuum plasma treatment of polyimide films

[0140] As a preliminary step before treating the polyimide film with a silane coupling agent, vacuum plasma treatment is performed on the polyimide film. The vacuum plasma treatment uses a device for treating long strip films, and vacuum exhaust is performed until the vacuum chamber reaches a depth of 1×10⁻⁶. -3 Below Pa, argon gas was introduced into the vacuum chamber, and plasma treatment was performed for 20 seconds under a discharge power of 100W and a frequency of 15kHz. By winding the plasma-treated film into a roll within the treatment device, it was ensured that the film's moisture absorption state was almost identical to that during plasma treatment. Samples of approximately 10cm square were directly cut from the plasma-treated film, and the moisture absorption rate was measured. The results showed that the moisture absorption rate of F2 was 0.21%, and that of F9 was 0.28%. Furthermore, the moisture absorption rates of F7 before and after plasma treatment were 0.20% and 0.22%, respectively.

[0141] [Manufacturing Example 1 (Manufacturing of Polyimide Solution 1)]

[0142] In a reaction vessel equipped with a nitrogen inlet pipe, a reflux pipe, and a stir bar, nitrogen gas was introduced while 19.86 parts by mass of 4,4′-diaminodiphenyl sulfone (4,4′-DDS), 4.97 parts by mass of 3,3′-diaminodiphenyl sulfone (3,3′-DDS), and 80 parts by mass of γ-butyrolactone (GBL) were added. Subsequently, 31.02 parts by mass of 4,4′-oxyphthalic dianhydride (ODPA), 24 parts by mass of GBL, and 13 parts by mass of toluene were added at room temperature. The temperature was raised to an internal temperature of 160°C, and the mixture was heated under reflux at 160°C for 1 hour to induce imidization. After imidization, the temperature was raised to 180°C, and the reaction continued while removing the toluene. After 12 hours of reaction, the mixture was removed from the oil bath and allowed to return to room temperature. GBL was added until the solid content reached a concentration of 20% by mass, yielding a polyimide solution with a specific viscosity of 0.70 dl / g.

[0143] [Manufacturing Example 2 (Manufacturing of Polyamic Acid Solution 1)]

[0144] After purging the reaction vessel, which is equipped with a nitrogen inlet pipe, a reflux pipe, and a stir bar, 22.73 parts by mass of 4,4′-diaminobenzamide benzene (DABAN), 201.1 parts by mass of N,N-dimethylacetamide (DMAc), and a dispersion (Nissan Chemical Industry Co., Ltd. "SNOWTEX (registered trademark) DMAC-ST-ZL") formed by dispersing colloidal silica in dimethylacetamide as a lubricant were added, so that the silica (lubricant) accounted for 0.4% by mass of the total polymer solids in the polyamic acid solution and was completely dissolved. Subsequently, 19.32 parts by mass of 1,2,3,4-cyclobutanetetracarboxylic acid dianhydride (CBDA) was added in batches in solid form, and the mixture was stirred at room temperature for 24 hours. Then, 173.1 parts by mass of DMAc were added for dilution to obtain a polyamic acid solution 1 with a solid content (NV) of 10% by mass and a specific viscosity of 3.10 dl / g.

[0145] [Manufacturing Example 3 (Manufacturing of Polyamic Acid Solution 2)]

[0146] After purging the reaction vessel, which is equipped with a nitrogen inlet pipe, a reflux pipe, and a stir bar, 32.02 parts by mass of 2,2'-bis(trifluoromethyl)benzidine (TFMB), 252.1 parts by mass of N,N-dimethylacetamide (DMAc), and a dispersion (Nissan Chemical Industry Co., Ltd. "SNOWTEX (registered trademark) DMAC-ST-ZL") formed by dispersing colloidal silica in dimethylacetamide as a lubricant were added, so that the silica (lubricant) accounted for 0.4% by mass of the total polymer solids in the polyamic acid solution and was completely dissolved. Subsequently, 19.61 parts by mass of 1,2,3,4-cyclobutanetetracarboxylic acid dianhydride (CBDA) were added in batches in solid form, and the mixture was stirred at room temperature for 24 hours. Then, 165.7 parts by mass of DMAc were added for dilution to obtain a polyamic acid solution 2 with a solid content (NV) of 11% by mass and a specific viscosity of 3.50 dl / g.

[0147] [Manufacturing Example 4 (Preparation of Polyimide Film F3)]

[0148] On the surface of the unlubricated material of polyethylene terephthalate film A4100 (manufactured by Toyobo Co., Ltd.), a comma coating applicator was used to coat the polyamic acid solution 1 obtained in Manufacturing Example 2, so that the final film thickness was adjusted to 15 μm. The polyethylene terephthalate film A04100 was wound up in a hot air oven and dried at 100°C for 10 minutes. The dried, self-supporting polyamic acid film was peeled off from the support and passed into a needle tenter frame equipped with needle plates. The film was held by inserting needles into the ends of the film, and the needle plate spacing was adjusted to prevent the film from breaking and causing unnecessary slack. The film was heated at 200°C for 3 minutes, 250°C for 3 minutes, and 300°C for 6 minutes to carry out an imidization reaction. After cooling to room temperature for 2 minutes, the poorly planar parts at both ends of the film were cut off with a cutting machine and rolled into a roll to obtain a 500m long and 450mm wide polyimide film F3.

[0149] [Manufacturing Example 5 (Preparation of Polyimide Film F4)]

[0150] On the unlubricated surface of polyethylene terephthalate film A4100 (manufactured by Toyobo Co., Ltd.), a comma coater is used to coat the polyamic acid solution 1 obtained in Manufacturing Example 2 to adjust the final film thickness to 0.3 μm. The polyethylene terephthalate film A4100 is then wound up in a hot air oven and dried at 100°C for 10 minutes. After winding, it is placed on one side of the comma coater, and then the polyimide solution 1 obtained in Manufacturing Example 1 is coated onto the dried polyamic acid solution 1 to achieve a final film thickness of 25 μm. The film was dried at 100°C for 10 minutes. The resulting self-supporting polyamic acid film was then peeled off from the support and fed into a needle tenter frame equipped with needle plates. The film was held at the ends by inserting needles, ensuring the film would not break or become unnecessarily loose. The needle plate spacing was adjusted during the feeding process. The film was heated at 200°C for 3 minutes, 250°C for 3 minutes, and 300°C for 6 minutes to induce an imidization reaction. Subsequently, the film was cooled to room temperature for 2 minutes. The unflattened portions at both ends were cut off using a cutter, and the film was wound into a roll to obtain a 500m wide and 450mm wide polyimide film F4.

[0151] [Example 6 (Preparation of polyimide film F5)]

[0152] Except that the polyamic acid solution 1 obtained in manufacturing example 2 was changed to the polyamic acid solution 2 obtained in manufacturing example 3, the same operation was performed as in manufacturing example 5 to produce polyimide film F4, and polyimide film F5 was obtained.

[0153] [Manufacturing Example 7 (Preparation of Polyimide Film F6)]

[0154] On the surface of a non-lubricated material, polyethylene terephthalate film A04100 (manufactured by Toyobo Co., Ltd.), polyamic acid solution 1 obtained in Manufacturing Example 2 was coated using a comma coater to adjust the final film thickness to 1 μm. It was then dried at 90–110°C for 10 minutes. The film was then placed on one side of the comma coater, and subsequently, polyimide solution 1 obtained in Manufacturing Example 1 was coated onto the dried polyamic acid solution 1 to achieve a final film thickness of 20 μm. It was then dried at 90–110°C for 10 minutes. The resulting self-supporting polyamic acid film was peeled from the support and passed into a needle tenter frame equipped with needle plates. The film was held by inserting needles into the ends to prevent breakage and unnecessary slack. The needle plate spacing was adjusted for feeding, and the film was heated at 200°C for 3 minutes, 250°C for 3 minutes, and 300°C for 6 minutes to carry out an imidization reaction. Then, after cooling to room temperature for 2 minutes, the poorly planar parts at both ends of the film are cut off with a cutting machine and rolled into a roll to obtain a 500m wide and 450mm wide polyimide film F6.

[0155] [Manufacturing Example 8 (Preparation of Polyimide Film F8)]

[0156] Except that the final thickness of the polyamic acid solution 1 obtained in Manufacturing Example 2 on the polyimide solution 1 obtained in Manufacturing Example 1 was changed to 25 μm, the same operation was performed as when manufacturing the polyimide film F3 in Manufacturing Example 4 to obtain the polyimide film F8.

[0157] <Thickness Measurement of High Heat-Resistant Films>

[0158] The thicknesses of the polyimide films F1–F9 were measured using a micrometer (FEINPRUF, Millitron 1245D). The results are shown in Table 1.

[0159] <Tensive modulus of elasticity of high heat-resistant film>

[0160] Polyimide films F1 to F9 were cut into 100mm × 10mm strips along both the mechanical direction (MD direction) and the width direction (TD direction) to serve as test pieces. Using a tensile testing machine (Shimadzu Corporation, Autograph equipment name AG-5000A), at a tensile speed of 50mm / min and a chuck spacing of 40mm, the tensile modulus of elasticity in the MD and TD directions was measured. The results are shown in Table 1.

[0161] <Coefficient of linear expansion (CTE) of high heat-resistant films>

[0162] For polyimide films F1 to F9, the stretch rate was measured under the following conditions in the flow direction (MD direction) and width direction (TD direction), with the stretch rate / temperature measured at 15°C intervals, such as 30°C to 45°C and 45°C to 60°C. The measurement was continued until 300°C, and the average value of all measured values ​​was calculated as CTE. The results are shown in Table 1.

[0163] Device Name: MAC Science TMA4000S

[0164] Sample length: 20mm

[0165] Sample width: 2mm

[0166] Temperature at which heating begins: 25℃

[0167] End temperature of heating: 300℃

[0168] Heating rate: 5℃ / min

[0169] Atmosphere; Argon

[0170] Total transmittance

[0171] The total transmittance (TT) of the film was measured using a HAZEMETER (NDH5000, manufactured by Nippon Denshoku Co., Ltd.). A D65 lamp was used as the light source. Three identical measurements were performed, and the arithmetic mean was used.

[0172] <Yellow Index (YI)>

[0173] Using a colorimeter (ZE6000, manufactured by Nippon Denshoku Co., Ltd.) and a C2 light source, the tristimulus values ​​(XYZ) of the film were measured based on ASTM D1925, and the yellowness index (YI) was calculated according to the following formula. Additionally, three identical measurements were performed, and their arithmetic mean was used.

[0174] YI = 100 × (1.28X - 1.06Z) / Y

[0175] <Haze>

[0176] The haze of the film was measured using a HAZEMETER (NDH5000, manufactured by Nippon Denshoku Co., Ltd.). A D65 lamp was used as the light source. Three identical measurements were performed, and the arithmetic mean was used.

[0177] <Surface Roughness Ra>

[0178] The surface roughness (Ra) of the membrane was evaluated using atomic force microscopy (AFM). The membrane was fixed on the observation stage, and the surface roughness over a 5 μm square area was calculated. Measurements were taken at five locations in contact with the inorganic substrate: the center and four corners. The average Ra value was used. The Ra values ​​for the inorganic substrate were measured in the same manner. For the inorganic substrate, the Ra value after ultrasonic cleaning with pure water was used. A BRANSON 3200 ultrasonic cleaner was used for 3 minutes of ultrasonic cleaning.

[0179] <Nitrogen Element Ratio>

[0180] Before applying the high-heat-resistant film, the proportion of nitrogen on the peeled surface of the inorganic substrate (50mm × 50mm area) after ultrasonic cleaning with pure water was evaluated using ESCA. K-Alpha was used in the apparatus. + (Made by Thermo Fisher Scientific). The measurement conditions are as follows. It should be noted that background noise removal during analysis was performed using the Shirley method. Additionally, the average value of measurement results from at least three locations with a surface composition ratio is used.

[0181] • Measurement conditions

[0182] Excitation X-rays: Monochromatic Al Kg line

[0183] X-ray power: 12kV, 6mA

[0184] Photoelectron escape angle: 90°

[0185] Focal spot size:

[0186] Energy: 50eV

[0187] Step size: 0.1eV

[0188] (Example 1)

[0189] The method for coating a silane coupling agent onto a glass substrate was performed using the apparatus shown in Figure 1. Figure 1 is a schematic diagram of the apparatus for coating a silane coupling agent onto a glass substrate. The glass substrate 1 was cut to a size of 100mm × 100mm and used 0.7mm thick OA11G glass (manufactured by NEG Corporation). Furthermore, the glass substrate was prepared by washing and drying with pure water, followed by irradiation with a UV / O3 irradiator (LAN Technical SKR1102N-03) for 1 minute. 150g of 3-aminopropyltrimethoxysilane (silane coupling agent Shin-Etsu Chemical KBM903) was added to a 1L chemical liquid container, and the outer surface was heated to 43°C in a water bath. The generated steam was then introduced into the chamber along with dry air. The gas flow rate was 25L / min, and the substrate temperature was 24°C. The temperature of the clean, dry air was 23°C, and the humidity was 1.2% RH. Since the exhaust port was connected to a negative pressure exhaust port, a differential pressure gauge confirmed that the chamber had a negative pressure of approximately 10Pa.

[0190] Then, a polyimide film F1 (70mm × 70mm) was adhered to the silane coupling agent layer to obtain a laminate. An MCK laminator was used for adhesion under the following conditions: compressed air pressure: 0.6MPa; temperature: 22℃; humidity: 55%RH; lamination speed: 50mm / sec. The F1 / glass laminate was heated at 110℃ for 10 minutes, and the 90° peel strength between F1 and glass was measured. Subsequently, the glass was ultrasonically cleaned with pure water, and the silane coupling agent was applied again, followed by the adhesion of F1. The second adhesion surface of F1 was the same as the first adhesion surface.

[0191] (Example 2)

[0192] Except for changing the high heat-resistant film used from film F1 to film F2, the laminate was obtained in the same manner as in Example 1.

[0193] (Example 3)

[0194] Except that the first heat-resistant film is designated as film F2 and the second film is designated as film F1, a laminate is obtained in the same manner as in Example 1.

[0195] (Example 4)

[0196] Except for changing the high heat-resistant film used from film F1 to film F3, the laminate was obtained in the same manner as in Example 1.

[0197] (Example 5)

[0198] Except for changing the high heat-resistant film used from film F1 to film F4, a laminate was obtained in the same manner as in Example 1. In this case, the bonding surface to the glass substrate was a polyimide surface made from polyamic acid solution 1.

[0199] (Example 6)

[0200] Except for changing the high heat-resistant film used from film F1 to film F5, the laminate is obtained in the same manner as in Example 1. In this case, the bonding surface with the glass substrate is a polyimide surface made from polyamic acid solution 2.

[0201] (Example 7)

[0202] Except for changing the high heat-resistant film F1 to film F6, the same laminate was obtained as in Example 1.

[0203] (Comparative Example 1)

[0204] Except for changing the high heat-resistant film used from film F1 to film F7, a laminate was obtained in the same manner as in Example 1. The surface roughness Ra of film F7 is increased, resulting in high adhesion strength to the inorganic substrate. In addition, the surface roughness Ra of the inorganic substrate after film F7 is peeled off also increases, making the inorganic substrate unusable.

[0205] (Comparative Example 2)

[0206] Except for changing the high heat-resistant film used from film F1 to film F8, the laminate was obtained in the same manner as in Example 1. After film F8 was peeled off, the surface roughness Ra of the inorganic substrate increased, and the inorganic substrate could not be reused.

[0207] (Comparative Example 3)

[0208] Except for changing the high heat-resistant film used from film F1 to film F9, the laminate was obtained in the same manner as in Example 1. Film F9 has high adhesion strength to the inorganic substrate. However, the surface roughness Ra of the inorganic substrate increases after film F9 is peeled off, making the inorganic substrate unusable.

[0209] (Refer to Example 1)

[0210] The first high heat-resistant film used is film F2, which uses an inorganic substrate with a surface nitrogen content of 14 atomic percent. The increased Ra of the inorganic substrate makes it difficult to adhere F2.

[0211] <Determination of 90° Adhesive Strength (Peel Strength)>

[0212] The laminate obtained from the above-described fabrication was heat-treated at 100°C for 10 minutes in atmospheric atmosphere. Subsequently, the 90° peel strength between the glass substrate and the polyimide film was measured. The results are shown in Table 1.

[0213] The conditions for determining the initial peel strength at 90° are as follows.

[0214] The film is stretched and peeled at an angle of 90° relative to the inorganic substrate.

[0215] Five measurements were performed, and the average value was taken as the measured value.

[0216] Measuring device; Autograph AG-IS manufactured by Shimadzu Corporation

[0217] Measurement temperature: Room temperature (25℃)

[0218] Peeling speed: 100 mm / min

[0219] Atmosphere; Atmosphere

[0220] Measure the sample width; 2.5cm

[0221] Table 1

[0222]

Claims

1. A method for manufacturing a second laminate, comprising: (a) a step of peeling a first high heat-resistant film from a first laminate to obtain an inorganic substrate, and (b) a step of laminating a second high heat-resistant film on the surface of the inorganic substrate over which the first high heat-resistant film is laminated to obtain a second laminate, wherein the first laminate is a first laminate consisting of a first high heat-resistant film, an inorganic substrate, and a silane coupling agent layer between the high heat-resistant film and the inorganic substrate, and the first laminate has the following characteristics (1) to (5): (1) the tensile elasticity of the first high heat-resistant film The modulus is 4 GPa or higher, (2) the bonding strength between the first high heat-resistant film and the inorganic substrate is 0.3 N / cm or lower, (3) the surface roughness Ra of the contact surface between the first high heat-resistant film and the inorganic substrate is 5 nm or lower, (4) the surface roughness Ra of the inorganic substrate surface after peeling the first high heat-resistant film from the first laminate is 3 nm or lower, (5) the nitrogen content of the bonding surface between the inorganic substrate and the first high heat-resistant film is 0.2 atomic% or higher and 12 atomic% or lower, and the second laminate has the following (6)~ (9) Features: (6) The tensile modulus of the second high heat-resistant film is 4 GPa or more; (7) The adhesive strength between the second high heat-resistant film and the inorganic substrate is 0.3 N / cm or less; (8) The surface roughness Ra of the contact surface between the second high heat-resistant film and the inorganic substrate is 5 nm or less; (9) The surface roughness Ra of the inorganic substrate surface after peeling the second high heat-resistant film from the second laminate is 3 nm or less. The tensile modulus of elasticity is determined as follows: using a tensile testing machine, at a tensile speed of 50 mm / min and a chuck spacing of 4 Under 0mm conditions, the tensile modulus of elasticity in the mechanical direction and the width direction of the test piece were measured respectively. The adhesive strength was measured as follows: the laminate was heat-treated at 100°C for 10 minutes in an atmospheric atmosphere, and then the 90° peel strength between the glass substrate and the high heat-resistant film was measured at a peel speed of 100mm / min in an atmospheric atmosphere at room temperature. The surface roughness Ra was measured as follows: the surface roughness in a 5μm square area at the contact position between the high heat-resistant film and the inorganic substrate was measured using an atomic force microscope.

2. The method for manufacturing the second laminate according to claim 1, wherein, The coefficient of linear expansion of the first high heat-resistant film is below 50 ppm / K. The coefficient of linear expansion is determined as follows: the shrinkage rate of the first high heat-resistant film in the mechanical direction and the width direction is measured under the following conditions, and the shrinkage rate / temperature is measured at 15°C intervals up to 300°C. The average value of all measured values ​​is calculated as the coefficient of linear expansion. Sample length: 20 mm; Sample width: 2 mm; Heating start temperature: 25°C; Heating end temperature: 300°C; Heating rate: 5°C / min; Atmosphere: Argon.

3. The method for manufacturing the second laminate according to claim 1, wherein, It further has the following (10) feature: (10) the nitrogen content of the bonding surface between the inorganic substrate and the second high heat-resistant film is more than 0.2 atomic% and less than 12 atomic%.

4. The method for manufacturing the second laminate according to claim 1, wherein, The coefficient of linear expansion of the second high heat-resistant film is below 50 ppm / K. The coefficient of linear expansion is determined as follows: the shrinkage rate of the second high heat-resistant film in the mechanical direction and the width direction is measured under the following conditions, and the shrinkage rate / temperature is measured at 15°C intervals up to 300°C. The average value of all measured values ​​is calculated as the coefficient of linear expansion. Sample length: 20 mm; Sample width: 2 mm; Heating start temperature: 25°C; Heating end temperature: 300°C; Heating rate: 5°C / min; Atmosphere: Argon.

5. A method for manufacturing a flexible electronic device, characterized in that, After obtaining the second laminate according to any one of claims 1 to 4, it has the following steps: (c) forming electronic components or circuits on the surface of the second high heat-resistant film and then peeling off the inorganic substrate.

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