TW202408793A - Laminate - Google Patents

Abstract

To provide a laminate of a polyimide film and a protective film, the laminate having favorable strength, handling properties, die-cutting processability, and winding-up performance. Provided is a laminate comprising a polyimide film and a protective film which is layered on at least one surface of the polyimide film. The yellowness index of the polyimide film is 10 or less. The protective film includes a polyethylene terephthalate structure. The product of the tensile modulus of elasticity E1 (GPa) and the film thickness T1 ([mu]m) of the laminate is 200-340.

Description

Laminated body

The present invention relates to a laminated body. In particular, it relates to a laminate of a polyimide film and a protective film that protects the polyimide film.

In recent years, as displays of various image display devices have become thinner, lighter, and more flexible, transparent resin films such as polyimide films and polyamide films have been widely used as materials to replace the glass used in the past. . A transparent resin film is laminated with a protective film on one side to prevent damage to the transparent resin film, a functional layer (such as a hard coat layer) is formed on the other side, and finally the protective film is peeled off and used for various purposes.

Examples of documents describing a laminate of a transparent resin film and a protective film include Patent Documents 1 to 3. [Prior technical literature] [Patent Document]

[Patent Document 1] Japanese Patent No. 6376271 [Patent Document 2] Japanese Patent No. 6450048 [Patent Document 3] Japanese Patent No. 6400875

[Problems to be solved by the invention]

However, from the viewpoint of excellent transparency and suppression of coloration, it is desirable to thin the transparent resin film into a thin film. On the other hand, the transparent resin film that is a thin film has weak toughness and is softer than necessary. Therefore, even when it is laminated with a protective film, its toughness is not sufficient. Therefore, if the laminated body is formed into a film roll, there are disadvantages in transportability such as wrinkles easily occurring. Furthermore, since the transparent resin film, which is a thin film, is easily damaged, careful handling is required, and there is a problem that is difficult to handle. In addition, there is a problem that wrinkles and damage are easily generated when the laminate is punched using Thomson mold processing or the like. On the other hand, although the toughness of the laminated body can be enhanced by increasing the thickness and elasticity coefficient of the protective film, if the toughness is enhanced beyond what is required, it becomes difficult to make the laminated body follow the winding roller, and it may also become difficult to The problem of obtaining a tightly wound film roll of a laminated body. The laminates disclosed in Patent Documents 1 to 3 have not examined toughness, transportability (handling properties), punching processability, and winding properties, and there is still room for improvement.

Therefore, the present invention is to solve the above-mentioned problem, and its purpose is to provide a laminate and a film roll of the laminate, wherein the laminate is a laminate of a polyimide film and a protective film, and its toughness, transportability (handling ability), punching processing suitability, and winding property are improved. [Means for solving the problem]

The inventors of the present invention conducted intensive research in order to solve the aforementioned problems and found that by setting the product of the elastic coefficient and the thickness of the laminate of the polyimide film and the protective film within a certain range, the laminate and the laminate can be improved. The toughness, transportability, punching processability, and winding properties of the laminated film roll are what lead to the completion of the present invention.

That is, the present invention includes the following structures.

[1] A laminate comprising a polyimide film and a protective film laminated on at least one surface of the polyimide film, wherein the product of the tensile modulus E1 (GPa) and the film thickness T1 (μm) of the laminate is 200 or more and 340 or less. [2] The laminate as described in [1], wherein the elastic modulus Epf of the protective film is 1.0 GPa or more. [3] The laminate as described in [1] or [2], wherein the protective film comprises a polyester film and an adhesive layer. [4] The laminate as described in any one of [1] to [3], wherein the tensile modulus Epi of the polyimide film is 3.0 GPa or more. [5] A laminate as described in any one of [1] to [4], wherein the yellowness index of the polyimide film is 10.0 or less. [6] A laminate as described in any one of [1] to [5], wherein the film thickness T1 of the laminate is 150 μm or less. [Effect of the Invention]

The laminate of the polyimide film and the protective film of the present invention has good toughness. Moreover, even when the laminate is made into a film roll, it has excellent transportability (handling property), winding property, and punching processing suitability.

[Form used to implement the invention]

The following describes the implementation of the present invention.

＜Polyimide membrane＞ The polyimide film of the present invention is not particularly limited as long as it has a polyimide structure. Examples include: aromatic polyamideimide film, aliphatic polyamideimide film, alicyclic polyamideimide film, aromatic polyamideimide film, aliphatic polyamideimide film, lipid Cyclic polyamide imide membranes, and membranes mixed with these. Preferably, it is an aromatic polyimide film, an aliphatic polyimide film, or an alicyclic polyimide film. Usually, a polyimide film is made by mixing diamines and tetracarboxylic acids in a solvent, and then coating the polyamide acid (polyimide precursor) solution obtained by the reaction on a support for making a polyimide film. and drying to prepare a green membrane (hereinafter also referred to as "polyimide film"), and the green membrane is further placed on a support for making a polyimide film, or in a state of being peeled off from the support. It is obtained by performing high-temperature heat treatment under high temperature to cause dehydration and ring-closure reaction.

The polyamide (polyimide precursor) solution can be applied by conventionally known solution application methods such as spin coating, scraper, applicator, notch wheel applicator, screen printing, slit coating, reverse coating, dip coating, curtain coating, and slit die coating.

The polyimide film of the present invention needs a yellow index (hereinafter also referred to as "Yellow Index" or "YI") of 10 or less. From the viewpoint of good transparency, 8 or less is preferred, 7 or less is more preferred, 6 or less is still more preferred, 5 or less is still more preferred, 4 or less is still more preferred, and 3 or less is particularly preferred. The lower limit of the yellowness index of the polyimide film is not particularly limited, but for use as a flexible electronic device, it is preferably 0.1 or more, more preferably 0.2 or more, and further preferably 0.3 or more. By setting the yellowness index of the polyimide film of the present invention within the above range, the transparency becomes good (it becomes a transparent polyimide film). The method for measuring the yellow index of the aforementioned polyimide film is based on the method described in the examples.

Examples of aromatic tetracarboxylic acids used to obtain colorless and highly transparent polyimide include 4,4'-(2,2-hexafluoroisopropylidene)diphthalic acid, 4,4'-oxydiphthalic acid, bis(1,3-dioxy-1,3-dihydro-2-benzofuran-5-carboxylic acid) 1,4-phenylene ester, bis(1,3-dioxy- 1,3-dihydro-2-benzofuran-5-yl)benzene-1,4-dicarboxylate, 4,4'-[4,4'-(3-oxo-1,3-dihydro-2-benzofuran-1,1-diyl)bis(benzene-1,4-diyloxy)]dibenzene-1,2-dicarboxylic acid, 3,3',4,4'-benzophenonetetracarboxylic acid, 4,4'-[(3-oxo-1,3-dihydro-2-benzofuran-1,1-diyl)bis(toluene-2,5-diyloxy)]dibenzene-1,2-dicarboxylic acid, 4,4'-[(3-oxo-1,3-dihydro-2-benzofuran-1,1-diyl)bis(1,4-xylene-2,5-diyloxy)]dibenzene-1,2-dicarboxylic acid, 4,4'-[4,4'-(3-oxo-1,3-dihydro-2-benzofuran-1,1-diyl)bis(4-isopropyl-toluene-2,5-diyloxy)]diphenyl-1,2-dicarboxylic acid, 4,4'-[4,4'-(3-oxo-1,3-dihydro-2-benzofuran-1,1-diyl)bis(naphthalene-1,4- diphenyl-1,2-dicarboxylic acid, 4,4'-[4,4'-(3H-2,1-benzoxathiol-1,1-dioxo-3,3-diyl)bis(benzene-1,4-diyloxy)]diphenyl-1,2-dicarboxylic acid, 4,4'-benzophenonetetracarboxylic acid, 4,4'-[(3H-2,1-benzoxathiol-1,1-dioxo-3,3-diyl)bis(toluene-2,5-diyloxy)]diphenyl-1,2-dicarboxylic acid, 4,4'-[(3H-2,1-benzoxathiol-1,1-dioxo-3,3-diyl)bis(1,4-xylene-2,5-diyloxy)]diphenyl-1,2-dicarboxylic acid, 4,4'-[4,4'-(3H-2,1-benzothiol-1,1-dioxo-3,3-diyl)bis(4-isopropyl-toluene-2,5-diyloxy)]diphenyl-1,2-dicarboxylic acid, 4,4'-[4,4'-(3H-2,1-benzothiol-1,1-dioxo-3,3-diyl)bis(naphthalene-1,4-diyloxy)]diphenyl-1,2-dicarboxylic acid, 3,3',4,4'-benzophenonetetracarboxylic acid, 3,3',4,4'-benzophenonetetracarboxylic acid, 3,3',4,4'-diphenylsulfonetetracarboxylic acid, 3,3',4,4'-biphenyltetracarboxylic acid, 2,3,3',4'-biphenyltetracarboxylic acid, pyromellitic acid, 4,4'-[spiro(𠮿) -9,9'-fluorinated)-2,6-diylbis(oxycarbonyl)]diphthalic acid, 4,4'-[spiro( Tetracarboxylic acids such as [(9,9'-fluorinated)-3,6-diylbis(oxycarbonyl)] diphthalic acid and their anhydrides. Among these, dianhydrides having two anhydride structures are preferred, and in particular, 4,4'-(2,2-hexafluoroisopropylidene) diphthalic acid dianhydride, 4,4'-oxydiphthalic acid dianhydride, 2,3,3',4'-biphenyltetracarboxylic acid dianhydride, and pyromellitic acid dianhydride are preferred. In addition, aromatic tetracarboxylic acids may be used alone or in combination of two or more. When heat resistance is important, the copolymerization amount of the aromatic tetracarboxylic acid is, for example, preferably 50 mass % or more of all tetracarboxylic acids, more preferably 60 mass % or more, further preferably 70 mass % or more, further preferably 80 mass % or more, particularly preferably 90 mass % or more, and 100 mass % is also acceptable.

Examples of alicyclic tetracarboxylic acids include: 1,2,3,4-cyclobutanetetracarboxylic acid, 1,2,3,4-cyclopentanetetracarboxylic acid, and 1,2,3,4-cyclohexane Tetracarboxylic acid, 1,2,4,5-cyclohexanetetracarboxylic acid, 3,3',4,4'-bicyclohexanetetracarboxylic 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]octane-7-ene-2,3,5,6- Tetracarboxylic acid, tetrahydroanthracene-2,3,6,7-tetracarboxylic acid, tetrahydroanthracene-1,4:5,8:9,10-trimethanoanthracene-2,3,6,7-tetracarboxylic acid Formic acid, decahydronaphthalene-2,3,6,7-tetracarboxylic acid, decahydro-1,4:5,8-dimethanonaphthalene-2,3,6,7-tetracarboxylic acid, decahydro- 1,4-ethano-5,8-methanonaphthalene-2,3,6,7-tetracarboxylic acid ), norbornane-2-spiro-α-cyclopentanone-α'-spiro-2''-norbornane-5,5'',6,6''-tetracarboxylic acid (alias "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-cyclo Hexanone-α'-spiro-2''-norbornane-5,5'',6,6''-tetracarboxylic acid (alias "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 Alkane-5,5'',6,6''-tetracarboxylic acid, norbornane-2-spiro-α-cyclobutanone-α'-spiro-2''-norbornane-5,5'', 6,6''-tetracarboxylic acid, norbornane-2-spiro-α-cycloheptanone-α'-spiro-2''-norbornane-5,5'',6,6''-tetracarboxylic acid , norbornane-2-spiro-α-cyclooctanone-α'-spiro-2''-norbornane-5,5'',6,6''-tetracarboxylic acid, norbornane-2-spiro -α-cyclononanone-α'-spiro-2''-norbornane-5,5'',6,6''-tetracarboxylic acid, norbornane-2-spiro-α-cyclodecanone-α '-Spiro-2''-norbornane-5,5'',6,6''-tetracarboxylic acid, norbornane-2-spiro-α-cycloundecanone-α'-spiro-2'' -Norbornane-5,5'',6,6''-tetracarboxylic acid, norbornane-2-spiro-α-cyclododecanone-α'-spiro-2''-norbornane-5, 5'',6,6''-tetracarboxylic acid, norbornane-2-spiro-α-cyclotridecone-α'-spiro-2''-norbornane-5,5'',6,6 ''-Tetracarboxylic acid, norbornane-2-spiro-α-cyclotetradecanone-α'-spiro-2''-norbornane-5,5'',6,6''-tetracarboxylic acid, norborne Bornane-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-(methyl Tetracarboxylic acids such as cyclohexanone)-α'-spiro-2''-norbornane-5,5'',6,6''-tetracarboxylic acid and their anhydrides. Among these, dianhydrides having two acid anhydride structures are ideal. In particular, 1,2,3,4-cyclobutanetetracarboxylic dianhydride and 1,2,3,4-cyclohexanetetracarboxylic dianhydride are preferred. Formic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, more preferably 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,4,5-cyclohexane Tetracarboxylic dianhydride, more preferably 1,2,3,4-cyclobutane tetracarboxylic dianhydride. In addition, these may be used individually or in combination of 2 or more types. When transparency is important, the copolymerization amount of alicyclic tetracarboxylic acids is, for example, preferably 50 mass% or more of all tetracarboxylic acids, more preferably 60 mass% or more, further preferably 70 mass% or more, and still more preferably It is preferably 80 mass% or more, particularly preferably 90 mass% or more, and 100 mass% is also acceptable.

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 diphenylsulfonate-3,3',4'-tricarboxylic acid, or hydrogenated products of the above aromatic tricarboxylic acids such as hexahydrotrimellitic acid, ethylene glycol trimellitic acid ester, propylene glycol trimellitic acid ester, 1,4-butanediol trimellitic acid ester, polyethylene glycol trimellitic acid ester, and anhydrides and esters thereof. Among these, anhydrides having one acid anhydride structure are preferred, and trimellitic anhydride and hexahydrotrimellitic anhydride are particularly preferred. These may be used alone or in combination.

Examples of dicarboxylic acids include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, and 4,4'-oxydibenzoic acid, or 1,6- Hydrogenates of the above aromatic dicarboxylic acids such as cyclohexanedicarboxylic acid, oxalic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid Acid, dodecanedioic acid, 2-methylsuccinic acid, and their chlorides or esters, etc. Among these, aromatic dicarboxylic acids and their hydrides are preferred, and in particular, terephthalic acid, 1,6-cyclohexanedicarboxylic acid, and 4,4'-oxydibenzoic acid are preferred. In addition, dicarboxylic acids can be used alone or in combination of multiple types.

There are no particular restrictions on the diamines or isocyanates used to obtain colorless and highly transparent polyimide, and aromatic diamines, aliphatic diamines, alicyclic diamines, aromatic diisocyanates, aliphatic diisocyanates, alicyclic diisocyanates, etc., which are commonly used in polyimide synthesis, polyamide imide synthesis, and polyamide synthesis, can be used. From the perspective of heat resistance, aromatic diamines are preferred, and from the perspective of transparency, alicyclic diamines are preferred. In addition, if aromatic diamines having a benzoxazole structure are used, it becomes possible to exhibit high heat resistance, high elastic modulus, low thermal shrinkage, and low linear expansion coefficient. The diamines and isocyanates may be used alone or in combination of two or more.

Examples of the 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- 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, 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 sulfide, 3,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfide, 3,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfide, ,3'-diaminodiphenylsulfone, 3,4'-diaminodiphenylsulfone, 4,4'-diaminodiphenylsulfone, 3,3'-diaminobenzophenone, 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]methane 1,2-bis[4-(4-aminophenoxy)phenyl]ethane, 1,1-bis[4-(4-aminophenoxy)phenyl]propane, 1,2-bis[4-(4-aminophenoxy)phenyl]propane, 1,3-bis[4-(4-aminophenoxy)phenyl]propane, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 1,1-bis[4-(4-aminophenoxy)phenyl]butane, 1,3 -Bis[4-(4-aminophenoxy)phenyl]butane, 1,4-bis[4-(4-aminophenoxy)phenyl]butane, 2,2-bis[4-(4-aminophenoxy)phenyl]butane, 2,3-bis[4-(4-aminophenoxy)phenyl]butane, 2-[4-(4-aminophenoxy)phenyl]-2-[4-(4-aminophenoxy)-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- 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]sulfide, bis[4-(4-aminophenoxy)phenyl]sulfide, bis[4-(4-aminophenoxy)phenyl]sulfide, bis[4-(4-aminophenoxy)phenyl]sulfide, bis[4-(4-aminophenoxy)phenyl]sulfide, bis[4-(3-aminophenoxy)phenyl]ether, bis[4-(4-aminophenoxy)phenyl] ether, 1,3-bis[4-(4-aminophenoxy)benzyl]benzene, 1,3-bis[4-(3-aminophenoxy)benzyl]benzene, 1,4-bis[4-(3-aminophenoxy)benzyl]benzene, 4,4'-bis[(3-aminophenoxy)benzyl]benzene, 1,1-bis[4-(3-aminophenoxy)phenyl]propane, 1,3-bis[4-(3-aminophenoxy)phenyl]propane, 3,4'-bis[(3-aminophenoxy)phenyl]propane Aminodiphenyl 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]sulfone, 4,4'-bis[3-(4-aminophenoxy)phenyl] 4,4'-bis[3-(3-aminophenoxy)benzyl]diphenyl ether, 4,4'-bis[4-(4-amino-α,α-dimethylbenzyl)phenoxy]benzophenone, 4,4'-bis[4-(4-amino-α,α-dimethylbenzyl)phenoxy]diphenylsulfone, bis[4-{4-(4-aminophenoxy)phenoxy}phenyl]sulfone, 1,4-bis[4-(4-aminophenoxy)phenoxy-α, α-dimethylbenzyl]benzene, 1,3-bis[4-(4-aminophenoxy)phenoxy-α,α-dimethylbenzyl]benzene, 1,3-bis[4-(4-amino-6-trifluoromethylphenoxy)-α,α-dimethylbenzyl]benzene, 1,3-bis[4-(4-amino-6-fluorophenoxy)-α,α-dimethylbenzyl]benzene, 1,3-bis[4-(4-amino-6-methylphenoxy)-α,α-dimethylbenzyl]benzene, ,3-bis[4-(4-amino-6-cyanophenoxy)-α,α-dimethylbenzyl]benzene, 3,3'-diamino-4,4'-diphenoxybenzophenone, 4,4'-diamino-5,5'-diphenoxybenzophenone, 3,4'-diamino-4,5'-diphenoxybenzophenone, 3,3'-diamino-4-phenoxybenzophenone, 4,4'-diamino-5-phenoxybenzophenone, 3,4'-diamino -4-phenoxybenzophenone, 3,4'-diamino-5'-phenoxybenzophenone, 3,3'-diamino-4,4'-diphenyloxybenzophenone, 4,4'-diamino-5,5'-diphenyloxybenzophenone, 3,4'-diamino-4,5'-diphenyloxybenzophenone, 3,3'-diamino-4-diphenyloxybenzophenone, 4,4'-diamino-5-diphenyloxybenzophenone, 3,4'-diamino-4,5'-diphenyloxybenzophenone 1,3-Bis(3-amino-4-phenoxybenzyl)benzene, 1,4-Bis(3-amino-4-phenoxybenzyl)benzene, 1,3-Bis(4-amino-5-phenoxybenzyl)benzene, 1,4-Bis(4-amino-5-phenoxybenzyl)benzene, 1,3-Bis(3-amino-4-biphenyloxybenzyl)benzene , 1,4-bis(3-amino-4-biphenyloxybenzyl)benzene, 1,3-bis(4-amino-5-biphenyloxybenzyl)benzene, 1,4-bis(4-amino-5-biphenyloxybenzyl)benzene, 2,6-bis[4-(4-amino-α,α-dimethylbenzyl)phenoxy]benzonitrile, 4,4'-[9H-fluorene-9,9-diyl]bisaniline (also known as "9,9-bis(4-aminophenyl)fluorene"), spiro(𠮿 -9,9'-fluorinated)-2,6-diylbis(oxycarbonyl)]bisaniline, 4,4'-[spiro(𠮿 -9,9'-fluorinated)-2,6-diylbis(oxycarbonyl)]bisaniline, 4,4'-[spiro(𠮿 [0043] In addition, part or all of the hydrogen atoms on the aromatic ring of the above aromatic diamine may be substituted by a halogen atom, an alkyl or alkoxy group having 1 to 3 carbon atoms, or a cyano group. Furthermore, part or all of the hydrogen atoms of the alkyl or alkoxy group having 1 to 3 carbon atoms may be substituted by a halogen atom. The aromatic diamines having a benzoxazole structure are not particularly limited, and examples thereof include 5-amino-2-(p-aminophenyl)benzoxazole, 6-amino-2-(p-aminophenyl)benzoxazole, 5-amino-2-(m-aminophenyl)benzoxazole, 6-amino-2-(m-aminophenyl)benzoxazole, 2,2'-p-phenylenebis(5-aminobenzoxazole), 2,2'-p-phenylenebis(6-aminobenzoxazole), 1-(5-aminobenzoxazole-4-(6-aminobenzoxazole-1-yl)benzoxazole, 2,6-(4,4'-diaminodiphenyl)benzoxazole, 1,2-d:5,4-d'] bis(oxazole), 2,6-(4,4'-diaminodiphenyl)benzo[1,2-d:4,5-d'] bis(oxazole), 2,6-(3,4'-diaminodiphenyl)benzo[1,2-d:5,4-d'] bis(oxazole), 2,6-(3,4'-diaminodiphenyl)benzo[1,2-d:4,5-d'] bis(oxazole), 2,6-(3,3'-diaminodiphenyl)benzo[1,2-d:5,4-d'] bis(oxazole), 2,6-(3,3'-diaminodiphenyl)benzo[1,2-d:4,5-d'] bis(oxazole), etc. Among these, 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 4-amino-N-(4-aminophenyl)benzamide, 4,4'-diaminodiphenylsulfone, and 3,3'-diaminobenzophenone are particularly preferred. In addition, the aromatic diamines may be used alone or in combination of a plurality of them.

Examples of alicyclic diamines include 1,4-diaminocyclohexane, 1,4-diamino-2-methylcyclohexane, and 1,4-diamino-2-ethane. cyclohexane, 1,4-diamino-2-n-propylcyclohexane, 1,4-diamino-2-isopropylcyclohexane, 1,4-diamino-2-n-propylcyclohexane Butylcyclohexane, 1,4-diamino-2-isobutylcyclohexane, 1,4-diamino-2-butylcyclohexane, 1,4-diamino-2 -Tertiary butylcyclohexane, 4,4'-methylenebis(2,6-dimethylcyclohexylamine), etc. Among these, 1,4-diaminocyclohexane and 1,4-diamino-2-methylcyclohexane are particularly preferred, and 1,4-diaminocyclohexane is more preferred. . In addition, alicyclic diamines can be used individually or in combination of multiple types.

Examples of diisocyanates include diphenylmethane-2,4'-diisocyanate, 3,2'- or 3,3'- or 4,2'- or 4,3'- or 5,2'- or 5,3'- or 6,2'- or 6,3'-dimethyldiphenylmethane-2,4'-diisocyanate, 3,2'- or 3,3'- or 4,2'- or 4,3'- or 5,2'- or 5,3'- or 6,2'- or 6,3'-diethyldiphenylmethane -2,4'-diisocyanate, 3,2'- or 3,3'- or 4,2'- or 4,3'- or 5,2'- or 5,3'- or 6,2'- or 6,3'-dimethoxydiphenylmethane-2,4'-diisocyanate, diphenylmethane-4,4'-diisocyanate, diphenylmethane-3,3'-diisocyanate, diphenylmethane-3,4'-diisocyanate, diphenyl ether-4,4'-diisocyanate, benzophenone-4,4' -diisocyanate, diphenyl sulfone-4,4'-diisocyanate, methylphenyl-2,4-diisocyanate, methylphenyl-2,6-diisocyanate, m-xylylene diisocyanate, p-xylylene diisocyanate, naphthalene-2,6-diisocyanate, 4,4'-(2,2-bis(4-phenoxyphenyl)propane) diisocyanate, 3,3'- or 2,2'-dimethylbiphenyl-4,4'-diisocyanate, 3,3'- or 2,2'-diethyl Aromatic diisocyanates such as 4,4'-diisocyanate, 3,3'-dimethoxybiphenyl-4,4'-diisocyanate, and 3,3'-diethoxybiphenyl-4,4'-diisocyanate, and diisocyanates obtained by hydrogenating any of these (e.g., isophorone diisocyanate, 1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, and hexamethylene diisocyanate). Among these, diphenylmethane-4,4'-diisocyanate, tolylphenyl-2,4-diisocyanate, tolylphenyl-2,6-diisocyanate, 3,3'-dimethylbiphenyl-4,4'-diisocyanate, naphthalene-2,6-diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, and 1,4-cyclohexane diisocyanate are preferred from the viewpoints of low moisture absorption, dimensional stability, price, and polymerizability. In addition, the diisocyanates may be used alone or in combination of a plurality of them.

In this embodiment, the use of a polyimide film provides excellent heat resistance and can be cut preferably using an ultraviolet laser.

The glass transition temperature of the polyimide film of the present invention is preferably above 300°C. From the viewpoint of good heat resistance, the temperature is more preferably 350°C or higher, still more preferably 375°C or higher, and still more preferably 400°C or higher. If the glass transition temperature is within the aforementioned range, it can withstand a heat treatment process of over 300°C when manufacturing flexible electronic devices, which is therefore preferable. The upper limit is not particularly limited, but industrially it may be 500°C or lower. The method for measuring the glass transition temperature of the polyimide film is based on the method described in the examples.

The thickness of the polyimide film is preferably 3 μm or more, more preferably 7 μm or more, further preferably 14 μm or more, and still more preferably 20 μm or more. In order to exhibit excellent optical properties, the upper limit of the film thickness of the polyimide film is preferably 40 μm or less, and more preferably 30 μm or less. By setting it within the aforementioned range, the transparency and toughness of the polyimide film become good.

The average coefficient of linear expansion (CTE) of the polyimide film between 30°C and 250°C is preferably 65ppm/K or less. It is more preferably 55ppm/K or less, further preferably 45ppm/K or less, further preferably 35ppm/K or less, particularly preferably 25ppm/K or less, further preferably 15ppm/K or less, and particularly preferably 10ppm/K or less. Moreover, it is preferably -5ppm/K or more, more preferably -3ppm/K or more, and further preferably 1ppm/K or more. If the CTE is within the above range, the difference in linear expansion coefficient with a general support (e.g., a glass substrate) can be kept small, and even if it is provided to a heating process, it can prevent the polyimide film from peeling off from the support or the entire support from bending. Here, CTE refers to the factor of reversible expansion and contraction relative to temperature. In addition, the CTE of the aforementioned polyimide film refers to the average value of the CTE in the coating direction (MD direction) and the CTE in the width direction (TD direction) of the polyimide solution or the pre-dried solution of the polyimide. The method for measuring the CTE of the aforementioned polyimide film is based on the method described in the embodiment.

The polyimide film of the present invention preferably has a total light transmittance of more than 75%. From the viewpoint of good transparency, it is more preferably 80% or more, still more preferably 85% or more, still more preferably 87% or more, and particularly preferably 88% or more. The upper limit of the total light transmittance of the polyimide film is not particularly limited, but for use as a flexible electronic device, it is preferably 98% or less, and more preferably 97% or less. By setting the total light transmittance of the polyimide film of the present invention to the above range, the transparency becomes good (it becomes a transparent polyimide film). The method for measuring the total light transmittance of the polyimide film is based on the method described in the examples.

The haze of the polyimide film of the present invention is preferably 1.0 or less, more preferably 0.8 or less, further preferably 0.5 or less, and even more preferably 0.3 or less. The lower limit is not particularly limited, but industrially there is no problem as long as it is 0.01 or more, and 0.05 or more is also fine. By setting the haze of the polyimide film of the present invention to the above range, the transparency becomes good (becoming a transparent polyimide film). The method for measuring the haze of the polyimide film is based on the method described in the embodiment.

The tensile strength of the polyimide film of the present invention is preferably 60 MPa or more, more preferably 80 MPa or more, and further preferably 100 MPa or more. The upper limit of the tensile strength is not particularly limited, but is in fact less than about 1000 MPa. If the tensile strength is 60 MPa or more, the polyimide film can be prevented from breaking when peeling from the protective film. In addition, the tensile strength of the polyimide film refers to the average value of the tensile strength in the flow direction (MD direction) and the tensile strength in the width direction (TD direction) of the polyimide film.

The tensile elongation at break of the polyimide film of the present invention is preferably 1% or more, more preferably 5% or more, and further preferably 10% or more. If the tensile elongation at break is 1% or more, the operability is excellent. In addition, the tensile elongation at break of the polyimide film refers to the average value of the tensile elongation at break in the flow direction (MD direction) and the tensile elongation at break in the width direction (TD direction) of the polyimide film.

The tensile modulus of the polyimide film of the present invention is preferably 3.0 GPa or more, more preferably 4.0 GPa or more, further preferably 5.0 GPa or more, and further preferably 6.0 GPa or more. If the tensile modulus is 3.0 GPa or more, the polyimide film will have less elongation deformation when peeled off from the protective film, and the operability is excellent. In addition, if the tensile modulus of the polyimide film is 3.0 GPa or more, the vibration degree of the laminate during transportation and handling of the laminate with the protective film can be kept small. The tensile modulus is preferably 9.0 GPa or less, more preferably 8.8 GPa or less, and further preferably 8.5 GPa or less. If the tensile modulus is 9.0 GPa or less, the polyimide film can be used as a flexible film. Also, if the tensile modulus of the polyimide film is 9.0 GPa or less, the warping of the laminate after heating can be suppressed in the laminate of the protective film and the polyimide film. Furthermore, if the tensile modulus of the polyimide film is 9.0 GPa or less, it becomes easy to set the storage modulus of the polyimide film at 280°C to 9.0 GPa or less. The storage modulus of the polyimide film at 280°C is preferably 9.0 GPa or less, more preferably 8.0 GPa or less, and further preferably 7.0 GPa or less. Moreover, 0.1 GPa or more is preferred, 0.5 GPa or more is more preferred, and 1.0 GPa or more is further preferred. In addition, the tensile modulus and storage modulus of the polyimide film refer to the average values of the tensile modulus in the flow direction (MD direction) and the tensile modulus in the width direction (TD direction) of the polyimide film.

The thickness unevenness of the polyimide film of the present invention is preferably 20% or less, more preferably 12% or less, further preferably 7% or less, and particularly preferably 4% or less. If the thickness unevenness exceeds 20%, it may become difficult to apply to narrow areas. In addition, the thickness unevenness of the film can be determined based on the following formula by using, for example, a contact-type film thickness meter, randomly selecting about 10 positions from the film to be measured, measuring the film thickness. Uneven film thickness (%) =100×(maximum film thickness-minimum film thickness)÷average film thickness The preferred range and measuring method of thickness unevenness of the protective film and the laminate are the same as the preferred range and measuring method of the polyimide film mentioned above.

The polyimide film of the present invention is preferably obtained in the form of a long polyimide film with a width of 300 mm or more and a length of 10 m or more during its production. The shape of the core roll-shaped polyimide film is better. If the polyimide film is wound into a roll, transportation in the form of the polyimide film wound into a roll becomes easy.

In the aforementioned polyimide film, in order to ensure handleability and productivity, about 0.03 to 3% by mass of lubricant (particles) with a particle diameter of about 10 to 1000 nm is added/contained in the polyimide film. It is better to provide fine unevenness on the surface of the polyimide film to ensure sliding properties. The particle size of the lubricant is preferably 20 to 500 nm, more preferably 30 to 300 nm, further preferably 50 to 200 nm. By setting the particle size of the lubricant to 10 nm or more, sufficient sliding properties relative to the added amount can be achieved. In addition, by setting the particle size of the lubricant to 1000 nm or less, problems such as a decrease in mechanical strength and cloudiness of the film can be reduced. The aforementioned fine unevenness on the surface of the polyimide film is preferably provided on the surface opposite to the protective film (the surface that does not contact the protective film). It is preferable that the surface contacting the protective film does not have the aforementioned fine unevenness. .

The polyimide film may or may not have an adhesive layer on the surface that contacts the protective film. On the other hand, it is preferable that the surface opposite to the protective film (the surface not in contact with the protective film) does not have an adhesive layer.

The arithmetic mean height Sa of the surface of the polyimide film that does not contact the protective film is preferably 0.001 μm or more, more preferably 0.003 μm or more, and further preferably 0.005 μm or more. In addition, it is preferably 0.100 μm or less, more preferably 0.050 μm or less, and further preferably 0.020 μm or less. By setting it within the above range, the static friction coefficient μs and the dynamic friction coefficient μd with the protective film can be reduced. The arithmetic mean height Sa of the polyimide film can be controlled by the manufacturing conditions during molding (temperature, line speed, surface waviness of the clamping roller, clamping pressure, etc.). For example, if the forming temperature is lowered, the arithmetic mean height tends to decrease. By increasing the line speed and reducing the clamping pressure, the arithmetic mean height also tends to decrease. In addition, it can also be controlled by the storage conditions (temperature, humidity, storage time) of the formed polyimide film.

＜Protective film＞ The protective film of the present invention is not particularly limited as long as it is a peelable film that can protect the surface of the polyimide film, but a polyester film is preferred and contains a polyethylene terephthalate structure (hereinafter also referred to as PET structure) is more preferably, a PET structure containing 80 mass % or more is still more preferably, 90 mass % or more is further more preferably, 95 mass % or more is still more preferably, and 100 mass % is particularly preferably. By setting it within the aforementioned range, the protective film can exhibit a moderate tensile elasticity coefficient. Here, the moderate tensile elastic coefficient is not particularly limited as long as the effect of the present invention is not impaired, but it is preferably 1.0 GPa or more, more preferably 2.0 GPa or more, further preferably 3.0 GPa or more, and still more preferably The best value is above 3.5GPa. Furthermore, when laminated with a polyimide film, a laminated body having just the right toughness that is neither too soft nor too hard can be obtained, and the transportability (handling property) also becomes good. That is, the protective film is particularly preferably a polyethylene terephthalate film. Examples of structures other than the PET structure that may be included in the protective film include polytrimethylene terephthalate structure, polybutylene terephthalate structure, polyethylene naphthalate structure, and polynaphthalenedicarboxylic acid. Propylene glycol structure, polybutylene naphthalate structure, polyamide structure, polyimide structure, polyamide imine structure, etc.

The protective film may or may not have an adhesive layer on the surface in contact with the polyimide film, but it is preferred to have an adhesive layer. That is, it is preferred to have an adhesive layer between the polyimide film and the protective film. By having an adhesive layer on the protective film, self-adhesion can be exhibited. The adhesive layer is not particularly limited, but for example, a urethane-based, silicone-based, or acrylic-based adhesive layer can be used, preferably a silicone-based or acrylic-based adhesive layer. The adhesive layer can be produced by applying an adhesive dissolved in a solvent and drying it. On the other hand, it is preferred that the surface opposite to the polyimide film (the surface not in contact with the polyimide film) does not have an adhesive layer.

The thickness of the protective film is preferably 10 μm or more, more preferably 20 μm or more, further preferably 30 μm or more, further preferably 40 μm or more, particularly preferably 50 μm or more, and further preferably 60 μm or more. Also, 200 μm or less is preferred, and 150 μm or less is more preferred. By setting it within the above range, when laminated with a polyimide film, the toughness and handling properties of the laminate become good. In the case where the protective film has an adhesive layer, the thickness of the protective film is set to include the thickness of the adhesive layer.

The thickness of the protective film is preferably the same as or thicker than the thickness of the polyimide film. The ratio of the thickness of the protective film to the thickness of the polyimide film (thickness of the protective film/thickness of the polyimide film) is preferably 1.0 or more, more preferably 1.1 or more, further preferably 1.5 or more, further preferably 2.0 or more, and particularly preferably 2.5 or more. Also, preferably 10 or less, more preferably 8 or less, and further preferably 6 or less. By setting it within the above range, the toughness and transportability (handling property) of the laminate become good.

The protective film may also contain various additives in the protective film and/or adhesive layer as needed. Examples of the additives include fillers, antioxidants, light-resistant agents, anti-gelling agents, organic wetting agents, antistatic agents, surfactants, pigments, dyes, and the like.

The arithmetic mean height Sa of the surface of the protective film that does not contact the polyimide film is preferably 0.005 μm or more, more preferably 0.010 μm or more, and further preferably 0.020 μm or more. In addition, it is preferably 1.000 μm or less, more preferably 0.500 μm or less, and further preferably 0.200 μm or less. By setting it within the above range, the static friction coefficient μs and the dynamic friction coefficient μd with the protective film can be reduced. The arithmetic mean height Sa of the protective film can be controlled by the manufacturing conditions (temperature, line speed, surface waviness of the clamping roller, clamping pressure, etc.) when the protective film is formed. For example, if the forming temperature is lowered, the arithmetic mean height tends to decrease. By increasing the line speed and reducing the clamping pressure, the arithmetic mean height also tends to decrease. In addition, it can also be controlled by the storage conditions (temperature, humidity, storage time) of the protective film after forming. When using a commercially available protective film, the arithmetic mean height of the protective film used can also be measured before laminating with the polyimide film to select the appropriate one.

＜Laminated body＞ The laminate system of the present invention is a laminate in which the protective film is laminated on at least one surface of the polyimide. It doesn't hurt to layer a protective film on both sides of the polyimide. In the laminate system of the present invention, the product of the tensile elastic coefficient E1 (unit: GPa) of the laminate and the film thickness T1 (unit: μm) of the laminate is 200 to 340. The lower limit value is preferably 220 or more, more preferably 240 or more, further preferably 260 or more, and particularly preferably 280 or more. Moreover, the upper limit is preferably 335 or less, more preferably 330 or less, further preferably 325 or less, and particularly preferably 320 or less. By adjusting the product of E1 and T1 within the aforementioned range, the toughness and transportability (handling properties) of the laminated body become good. It can be adjusted within the aforementioned range by appropriately combining the polyimide film and the protective film. If the product of E1 and T1 is greater than the aforementioned lower limit, the toughness of the laminated body is sufficiently strong, and therefore wrinkles are less likely to occur during transportation, punching processing, and the like. On the other hand, if it is less than the above upper limit, the toughness of the laminated body is not too strong but is moderately soft. Therefore, in the step of winding the laminated body, it follows the roller well, and there is a gap between the core material and the laminated body or between the laminated bodies. There will be no gaps between them, and a uniform and tightly wound laminated film roll can be obtained.

The film thickness T1 (unit: μm) of the laminated body of the present invention is not particularly limited, but it is preferably 150 μm or less, more preferably 125 μm or less, and further preferably 100 μm or less. By setting the film thickness T1 of the laminated body to 150 μm or less, it becomes easier to make the laminated body follow the winding roller, and it becomes easier to obtain a film roll in which the laminated body is tightly wound.

The laminate of the present invention is preferably a laminate in which the static friction coefficient μs of the surface of the polyimide film opposite to the protective film and the surface of the protective film opposite to the polyimide film is less than 0.70, and preferably the dynamic friction coefficient μd is less than 0.60. The static friction coefficient μs is more preferably less than 0.65, further preferably less than 0.60, and particularly preferably less than 0.55. The lower limit of the static friction coefficient μs is not particularly limited, and it can be industrially greater than 0.10, and greater than 0.20. The dynamic friction coefficient μd is more preferably less than 0.55, further preferably less than 0.50, and particularly preferably less than 0.45. The lower limit of the dynamic friction coefficient μd is not particularly limited, and it may be 0.10 or more, or 0.20 or more in industry. By setting the static friction coefficient μs and the dynamic friction coefficient μd to be below the above upper limit values, when the laminate is wound into a film roll, the occurrence of damage caused by friction between the surface of the polyimide film opposite to the protective film and the surface of the protective film opposite to the polyimide film can be suppressed.

In order to make the static friction coefficient μs below 0.70 and the dynamic friction coefficient μd below 0.60, there is no particular limitation, but for example, a method of adding a lubricant to the polyimide film can be cited. Generally, the smaller the surface roughness, the greater the value of the friction coefficient. This means that the smoother the surface becomes, the greater the friction becomes. It can be thought that adding a lubricant to the polyimide film to give the surface a fine roughness is a method of reducing the friction coefficient.

The static friction coefficient μs and the dynamic friction coefficient μd may also change due to the degree and properties of the surface of the polyimide film and the protective film, and thus can be controlled by, for example, coating the surface with an appropriate coating for modification. In the present invention, for example, an adhesive layer may be formed on the surface of a polyethylene terephthalate film without an adhesive layer to control the static friction coefficient μs to be less than 0.70 and the dynamic friction coefficient μd to be less than 0.60.

In the laminate of the present invention, the sum of the arithmetic mean height Sa of the polyimide film and the arithmetic mean height Sa of the protective film is preferably 0.030 μm or more and 1.000 μm or less, more preferably 0.050 μm or more and 0.800 μm or less. Further, Preferably, it is 0.100 micrometer or more and 0.700 micrometer or less. By setting it within the aforementioned range, the static friction coefficient μs and the dynamic friction coefficient μd can be reduced.

In order to set the static friction coefficient μs and the dynamic friction coefficient μd below predetermined values, in addition to the above-mentioned methods, the compatibility between the polyimide film and the protective film is also important, and the combination of these is also important. [Example]

The present invention will be described in detail below using examples. However, the present invention is not limited to the following examples as long as the gist is not exceeded.

<Polymerization Example 1: Preparation of polyamide solution A1> After replacing nitrogen in the reaction vessel equipped with a nitrogen inlet pipe, a reflux pipe, and a stirring rod, 9.61 g of 2,2'-bis(trifluoromethyl)benzidine (TFMB) and 3.91 g of pyromellitic acid di Anhydride (PMDA) and 3.51 g of 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) were added as solids so that the total polymer solid content in the polyamic acid solution was N,N-dimethylacetamide (DMAc, 96.65g) was added at 0.15% by mass, completely dissolved, and stirred at room temperature for 24 hours. 0.03 g of maleic anhydride (MAA) was added 2 hours before stopping stirring, and thereafter a polyamide solution A1 (molar ratio of TFMB//PMDA/BPDA) with a solid content of 15% by mass and a reduced viscosity of 2.7dl/g was obtained. =1.00//0.60/0.40).

<Production Example 1: Preparation of polyimide film F1> The polyamide solution A1 was applied on the non-lubricated surface of the polyethylene terephthalate film A4100 (manufactured by Toyobo Co., Ltd.) using a notch wheel coater so that the final film thickness became 23 μm. . This is dried at 90 to 110°C for 10 minutes. The polyamide film that has obtained self-supporting properties after drying is peeled off from the support and passed through a pin comb tenter having a pin plate equipped with pins. The ends of the film are inserted into the pins and held to form the film. Adjust the distance between the needle plates so that they do not break or cause unnecessary slack, and transport them. Heat at 250°C for 3 minutes, at 300°C for 3 minutes, and at 370°C for 6 minutes to proceed with the imidization reaction. . Thereafter, the film was cooled to room temperature over 2 minutes, and the parts with poor flatness at both ends of the film were cut off using a cutting machine to obtain a polyimide film F1 with a width of 500 m and a width of 450 mm.

<Production Example 2: Production of Polyimide Film F2> Polyimide Film F2 was obtained in the same manner as Polyimide Film F1 except that the final film thickness was changed to 15 μm.

<Polymerization Example 2: Preparation of polyamide solution A2> After replacing nitrogen in a reaction vessel equipped with a nitrogen inlet pipe, a reflux pipe, and a stirring rod, 11.26 g of 2,2'-bis(trifluoromethyl)benzidine (TFMB), 3.43 g of 1,2,3 , 4-cyclobutanetetracarboxylic dianhydride (CBDA), 3.60g of 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA), 1.63g of 4,4'-oxydiphthalene After dicarboxylic dianhydride (ODPA) was added as a solid, N,N-dimethylacetamide (DMAc, 112.93 g) and allow it to completely dissolve and stir at room temperature for 24 hours. 0.03 g of maleic anhydride (MAA) was added 2 hours before stopping stirring, and thereafter a polyamide solution A2 (a combination of TFMB//CBDA/BPDA/ODPA) with a solid content of 15% by mass and a reduced viscosity of 2.7dl/g was obtained. Ear ratio=1.00//0.50/ 0.35/0.15).

<Production Example 3: Preparation of polyimide film F3> The polyimide solution A2 was applied on the non-lubricant surface of the polyethylene terephthalate film A4100 (manufactured by Toyobo Co., Ltd.) using a notch wheel coater so that the final film thickness became 24 μm. . The film A4100 made of polyethylene terephthalate is passed through a hot air furnace, rolled, and dried at 100°C for 10 minutes. The polyamide film that has obtained self-supporting properties after drying is peeled off from the support and passed through a pin comb tenter having a pin plate equipped with pins. The ends of the film are inserted into the pins and held to form the film. Adjust the distance between the needle plates so that they do not break or cause unnecessary slack, and transport them. Heat at 200°C for 3 minutes, at 250°C for 3 minutes, and at 300°C for 6 minutes to proceed with the imidization reaction. . Thereafter, the film was cooled to room temperature for 2 minutes, and the parts with poor flatness at both ends of the film were cut off using a cutting machine to obtain a polyimide film F3 with a width of 500 m and a width of 450 mm.

<Production Example 4: Preparation of polyimide film F4> Polyimide film F4 was obtained in the same manner as polyimide film F3 except that the final film thickness was changed to 25 μm.

<Manufacture Example 5: Production of polyimide film F5> Polyimide film F5 was obtained in the same manner as polyimide film F3 except that the final film thickness was changed to 41.5 μm.

<Manufacture Example 6: Production of polyimide film F6> Polyimide film F6 was obtained in the same manner as polyimide film F1 except that the final film thickness was changed to 42 μm.

＜Protective film＞ Protective films B1 and B2 were produced and used as follows. Protective films B3 to B5 were commercially available. B1 to B3 are PET-based protective films, and B4 to B5 are PE (polyethylene)-based protective films.

＜Preparation of protective film＞ Prepare the following substrates. PET film: Made by Toyobo Co., Ltd., A4100, 25μm, 50μm (polyethylene terephthalate film)

＜Preparation of protective film B1＞ The following was mixed to obtain adhesive composition C1. Specifically, 2-ethylhexyl acrylate: 85 parts by mass, methyl methacrylate: 15 parts by mass, acrylic acid: 3 parts by mass, and catalyst (2,2'-azobisisobutyronitrile): 1 Mass parts are polymerized in an ethyl acetate solvent under a nitrogen atmosphere to obtain an acrylic resin (ethyl acetate solvent, solid content 30% by mass, weight average molecular weight: 700,000 to 800,000). 100 parts by mass of the acrylic resin and 3 parts by mass of CORONATE L (polyisocyanate for coatings manufactured by TOSOH Co., Ltd.) were mixed to obtain adhesive composition C1. The obtained adhesive composition C1 was coated on a polyethylene terephthalate (PET) film (A4100, thickness 25 μm) produced by Toyobo Co., Ltd. that was previously corona-treated, and dried at 100°C to remove the solvent. A protective film B1 in which an adhesive layer with a thickness of 25 μm was formed on the PET film was obtained.

＜Preparation of protective film B2＞ Mix the following to obtain adhesive composition C2. Linear polyorganosiloxane having vinyl groups only at both ends (solvent-free type, weight average molecular weight: 80,000): 68.30 parts by mass Organohydrogen polysiloxane (solvent-free type, weight average molecular weight: 2,000): 0.41 parts by mass Platinum catalyst (PL-56 manufactured by Shin-Etsu Chemical Industry): 1.00 parts by mass Ultraviolet absorber (Cyasorb UV-3638 (manufactured by CYTEC Corporation)): 0.3 parts by mass Reaction control agent (3-methyl-1-butyn-3-ol): 0.10 parts by mass Toluene: 30.19 parts by mass The obtained adhesive composition C2 was coated on a polyethylene terephthalate (PET) film (A4100, thickness 50 μm) produced by Toyobo Co., Ltd. that was previously corona-treated, and dried at 100°C to remove the solvent. A protective film B2 in which an adhesive layer with a thickness of 10 μm was formed on the PET film was obtained.

<Commercially available protective films> Protective films B3, B4, and B5 are commercially available. B3: Industrial FIXFILM (registered trademark) HG2 manufactured by FUJICOPIAN Co., Ltd. (a polysilicone adhesive is layered on one surface of the PET film) B4: TORETEC (registered trademark) 7832C manufactured by Toray Advanced Film Co., Ltd. (a polysilicone adhesive is layered on one surface of the PE film) B5: TORETEC (registered trademark) N711A manufactured by Toray Advanced Film Co., Ltd. (a polysilicone adhesive is layered on one surface of the PE film)

(Making of layered body rolls) Example 1 The protective film B1 from which the release film was peeled off was bonded to the polyimide film F1 produced in the above-mentioned Production Example 1 in such a manner that the adhesive layer was in contact with the polyimide film to form a laminated body. The winding core with an outer diameter of 175 mm was The laminate roll 1 was obtained by winding it into a roll shape at a winding tension of 50N. The results are shown in Table 1.

Examples 2 to 6, Comparative Examples 1 to 4 Using the polyimide films F2 to F6 and protective films B1 to B5 produced in the above-mentioned production examples 2 to 6, a laminate was made in the same order as in Example 1 with the combination described in Table 1 to obtain laminate rolls 2 to 10. The results are shown in Table 1.

<Measurement of the thickness (T1 (μm)) of the laminate> The thickness (T1) of the laminate was measured using a high-precision digital micrometer (MDH-25M, manufactured by Mitutoyo Co., Ltd.). The full width was measured at 2 locations at both ends and 1 location in the center along the flow direction at intervals of 10 m, and the average value is shown in Table 1 as the result.

<Measurement of protective film thickness Tpf (μm)> The thickness of the protective film was measured using a high-precision digital micrometer (Mitutoyo Co., Ltd., MDH-25M). The full width was measured at 2 locations at both ends in the width direction and 1 location at the center along the flow direction at intervals of 10 m, and the average value is shown in Table 1 as the result.

＜Measurement of thickness Tpi (μm) of polyimide film＞ The thickness of the polyimide film was measured using a high-precision digital micrometer (Mitutoyo Co., Ltd., MDH-25M). The full width was measured at 2 locations at both ends in the width direction and 1 location at the center along the flow direction at intervals of 10 m, and the average value is shown in Table 1 as the result.

<Determination of tensile modulus of elasticity (E1 (GPa)) of laminate> The laminate of protective film and polyimide film was cut into short pieces of 100mm×10mm using a utility knife and used as the test piece of laminate. The tensile modulus of elasticity (E1) was measured using a tensile testing machine (Autograph, model AG-5000A, manufactured by Shimadzu Corporation) at a tensile speed of 50mm/min and a distance between the clamps of 40mm. The results are shown in Table 1.

<Measurement of tensile elastic coefficient (Epf (GPa)) of protective film> Use a utility knife to cut the protective film into short sticks of 100 mm × 10 mm and set them as test pieces of the protective film. The tensile elastic coefficient was measured using a tensile testing machine (Autograph manufactured by Shimadzu Corporation, model name AG-5000A) under the conditions of a tensile speed of 50 mm/min and a distance between clamps of 40 mm. The results are shown in Table 1.

＜Measurement of tensile elastic coefficient (Epi(GPa)) of polyimide film＞ The polyimide film was cut into short sticks of 100 mm × 10 mm using a utility knife and set as test pieces of the polyimide film. The tensile elastic coefficient was measured using a tensile testing machine (Autograph manufactured by Shimadzu Corporation, model name AG-5000A) under the conditions of a tensile speed of 50 mm/min and a distance between clamps of 40 mm. The results are shown in Table 1.

＜Transportability of laminate＞ The appearance of the laminated body rolls 1 to 9 was confirmed to evaluate the transportability of the laminated body. Those with no damage or wrinkles on the completed laminated body roll were rated as ○, and those with damage or wrinkles were rated as ×.

＜Punching suitability of laminated body＞ The following method was used to evaluate the toughness of the laminates 1 to 9. The test piece of the laminated body (a 100 mm × 100 mm test piece punched by Thomson die processing) was rated as ○ if it could be produced smoothly without any damage or wrinkles during production, and as ○ if it was produced with damage or wrinkles during production. Set to ×.

<Wrapping of laminated body> The appearance of laminated body rolls 1 to 9 was visually observed, and the wrapping of the laminated body was judged as "○" or "×" according to the following criteria. ○: No air mixing (bulging) between laminated bodies was observed. ×: Air mixing (bulging) between laminated bodies was observed.

＜Glass transition temperature＞ Prepare three test pieces of polyimide films. For each test piece, obtain the storage elastic coefficient (E'), loss elastic coefficient (E"), and loss elastic coefficient divided by the storage elastic coefficient under the following conditions. Use the temperature dependence curve of tanδ (=E”/E’) to find the peak temperature. The average value of the three test pieces was calculated and set as the glass transition temperature. Machine name: DMA Q800 manufactured by TA Instruments Sample length: 20mm Sample width: 5mm Heating start temperature: 25℃ End temperature of heating: 500℃ Heating rate: 10℃/min Measuring frequency: 10Hz

＜Measurement method of Yellow Index YI＞ Using a colorimeter (ZE6000, manufactured by Nippon Denshoku Co., Ltd.) and a C2 light source, the tristimulus XYZ values of the film were measured according to ASTM D1925, and the yellowness index (YI) was calculated by the following formula. In addition, the same measurement was performed three times, and the arithmetic mean value was used. YI=100×(1.28X-1.06Z)/Y

＜Coefficient of Linear Expansion (CTE)＞ For the polyimide film, the expansion ratio is measured under the following conditions. The expansion ratio/temperature at intervals of 15°C is measured such as 30°C to 45°C and 45°C to 60°C. The measurement is performed up to 300°C and all measurements are calculated. The average of the values is taken as CTE (ppm/K). Machine name: TMA4000S made by MAC Science Sample length: 20mm Sample width: 2mm Heating start temperature: 25℃ End temperature of heating: 300℃ Heating rate: 5℃/min Gas environment: Argon

<Total light transmittance> The total light transmittance (TT) of the film was measured using HAZEMETER (NDH5000, manufactured by Nippon Denshoku Co., Ltd.). D65 light was used as the light source. In addition, the same measurement was performed 3 times, and the arithmetic average was used.

＜Haze＞ The haze of the film was measured using HAZEMETER (NDH5000, manufactured by Nippon Denshoku Co., Ltd.). Use D65 lamp as light source. In addition, the same measurement was performed three times, and the arithmetic mean value was used.

[Table 1] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Comparative example 1 Comparative example 2 Comparative example 3 Polyimide membrane F1 F2 F3 F4 F3 F5 F1 F2 F6 Resin composition A1 A1 A2 A2 A2 A2 A1 A1 A1 YI 7.6 5.4 3.8 3.8 3.8 5.9 7.6 5.4 13.0 Film thickness Tpi (μm) twenty three 15 twenty four 25 twenty four 41.5 twenty three 15 42 Tensile elastic coefficient Epi (GPa) 6.9 6.9 4.0 4.0 4.0 4.0 6.9 6.9 6.9 Glass transition temperature (℃) 410 410 375 375 375 375 410 410 410 CTE(ppm/K) 7 7 52 52 52 60 7 7 7 Total transmittance (%) 86 86 88 88 88 86 86 86 86 Haze 0.3 0.3 0.3 0.3 0.3 0.5 0.3 0.3 0.3 protective film B1 B2 B1 B2 B3 B1 B3 B5 B1 Film thickness Tpf(μm) 50 60 50 60 61 50 61 30 50 Tensile elastic coefficient Epf (GPa) 3.5 3.7 3.5 3.7 3.6 3.5 3.6 0.4 3.5 Laminated body (film roll) 1 2 3 4 5 6 7 9 10 Film thickness T1(μm) 73 75 74 85 85 91.5 84 45 92 Tensile elastic coefficient E1 (GPa) 4.5 4.4 3.7 4.0 3.8 3.7 4.5 3.7 4.5 The product of E1 and T1 326 330 270 337 320 339 381 167 414 Transportability (handlingability) ○ ○ ○ ○ ○ ○ 〇 × 〇 Punching processability ○ ○ ○ ○ ○ ○ 〇 × 〇 Windability ○ ○ 〇 〇 〇 〇 × 〇 × [Possibility of industrial application]

The present invention can provide a laminate with improved toughness, handling properties, punching process suitability, and winding properties. The laminate can be used as a material to replace glass used in various image display devices, and can be expected to contribute to the thinning, lightening, and flexibility of the displays of various image display devices.

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Claims (6)

A laminate consisting of a polyimide film and a protective film laminated on at least one side of the polyimide film, wherein The product of the tensile elastic coefficient E1 (GPa) and the film thickness T1 (μm) of the laminate is 200 or more and 340 or less. The laminated body of Claim 1, wherein the tensile elastic coefficient Epf of the protective film is 1.0 GPa or more. The laminated body of claim 1 or 2, wherein the protective film has a polyester film and an adhesive layer. The laminated body of Claim 1 or 2, wherein the tensile elastic coefficient Epi of the polyimide film is 3.0 GPa or more. The laminated body of claim 1 or 2, wherein the yellow index of the polyimide film is 10.0 or less. The laminate according to claim 1 or 2, wherein the film thickness T1 of the laminate is 150 μm or less.