KR20220156808A - laminate - Google Patents

Abstract

In a polyimide film having a high tensile modulus, low CTE, and heat resistance or chemical resistance, laminated with a self-healing layer for imparting scratch resistance so as not to deteriorate visibility due to damage during handling, self-repairing during processing or bending A laminate that does not cause peeling or falling off of a repair layer is provided. A polyimide film having a tensile modulus of elasticity of 3 GPa or more in both the MD and TD directions, a CTE of -5 ppm/°C to +55 ppm/°C in both the MD and TD directions, and a solvent content of 0.5 to 5.0% by mass; , A laminate comprising a self-healing layer formed on at least one side of the polyimide film.

Description

laminate

The present invention relates to a laminate comprising a self-healing layer and a polyimide film. More specifically, it relates to a laminate made of a polyimide film that exhibits excellent transparency, self-healing properties and flexibility, and has excellent adhesion to a self-healing layer.

Conventionally, around front plates and electrodes of image display devices such as touch panels and displays, a hard coat layer is formed on a transparent substrate film for the purpose of imparting scratch resistance so that visibility is not deteriorated due to damage during handling. A film is used (Patent Document 1). On the other hand, in recent years, in order to provide both high portability and a large screen, a touch panel or display in which an image display portion can be folded has been proposed (Patent Document 2), and flexibility superior to that of the conventional hard coat film has been required.

The hard coat layer formed on the hard coat film has a high surface hardness to impart scratch resistance, but since a coat layer having a high surface hardness tends to be brittle, it has been difficult to achieve both excellent flexibility and flexibility. Therefore, as a means to replace the hard coat layer, a flexible and tough coat layer is formed to form a self-healing coat layer having a function of spontaneously disappearing deformation or damage caused by stress during handling or processing. One film has been proposed (Patent Document 3).

A transparent thermoplastic resin film made of polyethylene terephthalate (PET), acryl, polycarbonate (PC), triacetyl cellulose (TAC), polyolefin, or the like is generally used as a base film for such a self-healing film. These thermoplastic resin films are excellent in transparency and resistance to bending, and because they are easy to bond and process, they are also excellent in the adhesiveness of the self-healing coating layer (Patent Document 4).

On the other hand, technology development for directly forming functional elements such as electrodes and display elements on a base film has been carried out, and attempts have been made to use a polyimide film having heat resistance and chemical resistance instead of a general thermoplastic resin film for a base film for a hard coat film. It has become (Patent Documents 5 to 6).

Patent Document 1: Japanese Unexamined Patent Publication No. 2013-37323 Patent Document 2: Japanese Unexamined Patent Publication No. 2019-211778 Patent Document 3: Japanese Patent Publication No. 2016-516846 Patent Document 4: Japanese Unexamined Patent Publication No. 2016-147416 Patent Document 5: Japanese Unexamined Patent Publication No. 2019-51644 Patent Document 6: Japanese Unexamined Patent Publication No. 2019-105829

In order to directly form functional elements such as electrodes and display elements, a high tensile modulus, low CTE, and heat resistance or chemical resistance are required for base films. When a polyimide film suitable for such a base film is to be used as a base film for a self-healing film excellent in flexibility and bending resistance as exemplified in Patent Document 4, since the surface of the polyimide film is flat and low in activity, the polyimide film is Adhesion to the mid film is insufficient, and peeling or falling off of the coating layer tends to occur during the processing process or during bending.

On the other hand, the self-healing layer has a function of absorbing an external force during handling or processing to repair deformation or damage, and since it is formed on the entire surface of the image display device, it can have low tack, stain resistance, and chemical resistance. If necessary, a component with a high degree of crosslinking and compositionally low activity is used. Therefore, regarding the self-healing layer, the easily bonding layer exemplified in Patent Document 5 for the hard coat layer has insufficient adhesiveness, and peeling or falling off of the self-healing layer occurs easily during the processing process or during bending.

Thus, since both the polyimide film and the self-healing layer have low activity, it has been a problem to obtain adhesion between the self-healing layer and the polyimide film while exhibiting excellent transparency, self-healing properties, and flexibility.

The inventors of the present invention, as a result of intensive studies to solve the above problems, found that these problems could be solved and reached the present invention. That is, this invention has the following structures.

A polyimide film having a tensile modulus of elasticity of 3 GPa or more in both the MD and TD directions, a CTE of -5 ppm/°C to +55 ppm/°C in both the MD and TD directions, and a solvent content of 0.5 to 5.0% by mass; , A laminate comprising a self-healing layer formed on at least one side of the polyimide film.

It is preferable that the laminate has a recovery rate of 80% or more after applying a minute load of 0.5 mN to the surface from a Vickers square pyramid diamond indenter with a micro hardness tester and holding it for 5 seconds, then removing the load to 0.005 mN and holding it for 60 seconds. do. Further, in the laminate, it is preferable that the adhesion rate of the self-healing layer cut in a lattice shape to the polyimide film by the crosscut method of JIS K 5600-5-6 (1999) is 80% or more. Further, the laminate preferably has a yellow index of 10 or less, a light transmittance of 70% or more at a wavelength of 400 nm, and a total light transmittance of 85% or more. It is preferable that the self-healing layer is a polymer composition containing crosslinking points, and some or all of the crosslinking points are crosslinking points having mobility.

According to the present invention, even when a polyimide film having a low activity surface is used as a base film, a laminate having excellent self-healing properties and excellent adhesion to a self-healing layer can be provided. Moreover, since it has excellent transparency and flexibility, it is possible to provide a transparent laminate suitable for front plates and around electrodes of image display devices such as touch panels and displays in which an image display portion can be folded.

Hereinafter, the laminate of the embodiment of the present invention will be described. The laminate of the present invention is a laminate comprising a polyimide film and a self-healing layer formed on at least one side of the polyimide film. The polyimide film constituting the laminate of the present invention is a polymer film having an imide bond in the main chain, preferably a polyimide film or a polyamideimide film, more preferably a polyimide film.

It is preferable that the polyimide film of this invention is obtained by any of the following manufacturing methods. First, in the first method, a polyamic acid (polyimide precursor) solution obtained by polymerizing diamines and tetracarboxylic acids in a solvent is applied to a support for producing a polyimide film and dried to form a green film ("precursor film", Also referred to as "polyamic acid film" or "polyamic acid film"), and obtained by subjecting a green film to a high-temperature heat treatment on a support for producing a polyimide film or in a state peeled from the support to cause a dehydration ring closure polymerization reaction lose In addition, as a second method, a polyimide solution obtained by dehydration ring-closure polymerization of diamines and tetracarboxylic acids in a solvent is applied to a support for producing a polyimide film and dried to form a polyimide solution containing 1 to 50% by mass of a solvent. It is also obtained by setting it as a mid-film and further treating a polyimide film containing 1 to 50% by mass of a solvent at a high temperature on a support for polyimide film production or in a state peeled from the support and drying it.

Further, in the third method, a polyamideimide solution obtained by polymerizing diisocyanates and tricarbones in a solvent is applied to a support for producing a polyamideimide film and dried to obtain polyamide containing 1 to 50% by mass of a solvent. It is obtained by treating a polyamide-imide film containing 1 to 50% by mass of a solvent at a high temperature and drying it as a mid film, on a support for producing polyamide-imide, or in a state peeled from the support. On the other hand, in the above three production methods, dicarboxylic acids may be appropriately used.

As the above tetracarboxylic acids, tricarboxylic acids and dicarboxylic acids, aromatic tetracarboxylic acids (including acid anhydrides thereof) commonly used in polyimide synthesis or polyamideimide synthesis, aliphatic tetracarboxylic acids (these acid anhydrides), alicyclic tetracarboxylic acids (including their acid anhydrides), aromatic tricarboxylic acids (including their acid anhydrides), aliphatic tricarboxylic acids (including their acid anhydrides), alicyclic tricarboxylic acids Boxylic acids (including acid anhydrides thereof), aromatic dicarboxylic acids, aliphatic dicarboxylic acids, alicyclic dicarboxylic acids, and the like can be used. Among them, aromatic tetracarboxylic acid anhydrides or alicyclic tetracarboxylic acid anhydrides are preferable, aromatic tetracarboxylic acid anhydrides are more preferable from the viewpoint of heat resistance, and alicyclic tetracarboxylic acid anhydrides are more preferable from the viewpoint of light transmission (transparency). Carboxylic acids are more preferred. When the tetracarboxylic acid is an acid anhydride, it may have one or two anhydride structures in the molecule, but preferably one having two anhydride structures (dianhydride) is good. Tetracarboxylic acids, tricarboxylic acids, and dicarboxylic acids may be used alone or in combination of two or more.

As aromatic tetracarboxylic acids for obtaining polyimide with high heat resistance in the present invention, 4,4'-(2,2-hexafluoroisopropylidene)diphthalic acid, 4,4'-oxydiphthalic acid, bis (1,3-dioxo-1,3-dihydro-2-benzofuran-5-carboxylic acid) 1,4-phenylene, bis(1,3-dioxo-1,3-dihydro-2 -benzofuran-5-yl)benzene-1,4-dicarboxylate, 4,4'-[4,4'-(3-oxo-1,3-dihydro-2-benzofuran-1,1 -Diyl)bis(benzene-1,4-diyloxy)]dibenzene-1,2-dicarboxylic acid, 3,3',4,4'-benzophenonetetracarboxylic acid, 4,4'- [(3-oxo-1,3-dihydro-2-benzofuran-1,1-diyl)bis(toluene-2,5-diyloxy)]dibenzene-1,2-dicarboxylic acid, 4 ,4'-[(3-oxo-1,3-dihydro-2-benzofuran-1,1-diyl)bis(1,4-xylene-2,5-diyloxy)]dibenzene-1, 2-dicarboxylic acid, 4,4'-[4,4'-(3-oxo-1,3-dihydro-2-benzofuran-1,1-diyl)bis(4-isopropyl-toluene- 2,5-diyloxy)]dibenzene-1,2-dicarboxylic acid, 4,4'-[4,4'-(3-oxo-1,3-dihydro-2-benzofuran-1 ,1-diyl)bis(naphthalene-1,4-diyloxy)]dibenzene-1,2-dicarboxylic acid, 4,4'-[4,4'-(3H-2,1-benzoxa Thiol-1,1-dioxide-3,3-diyl)bis(benzene-1,4-diyloxy)]dibenzene-1,2-dicarboxylic acid, 4,4'-benzophenonetetracarboxylic Acid, 4,4'-[(3H-2,1-benzoxathiol-1,1-dioxide-3,3-diyl)bis(toluene-2,5-diyloxy)]dibenzene-1, 2-dicarboxylic acid, 4,4'-[(3H-2,1-benzoxathiol-1,1-dioxide-3,3-diyl)bis(1,4-xylene-2,5-di yloxy)]dibenzene-1,2-dicarboxylic acid, 4,4'-[4,4'-(3H-2,1-benzoxathiol-1,1-dioxide-3,3-diyl )bis(4-isopropyl-toluene-2,5-diyloxy)]dibenzene-1,2-dicarboxylic acid, 4,4'-[4,4'-(3H-2,1-benz Oxathiol-1,1-dioxide-3,3-diyl)bis(naphthalene-1,4-diyloxy)]dibenzene-1,2-dicarboxylic acid, 3,3',4,4' -benzophenone tetracarboxylic 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(xanthene-9,9'-fluorene)-2,6-diylbis(oxycarbonyl)]dibenzene- 1,2-dicarboxylic acid, 4,4'-[spiro(xanthene-9,9'-fluorene)-3,6-diylbis(oxycarbonyl)]dibenzene-1,2-dicar Tetracarboxylic acids and acid anhydrides thereof, such as a boxylic acid, are mentioned. Among these, dianhydrides having two acid anhydride structures are suitable, particularly 4,4'-(2,2-hexafluoroisopropylidene)diphthalic dianhydride and 4,4'-oxydiphthalic dianhydride. this is preferable On the other hand, aromatic tetracarboxylic acids may be used independently or may use 2 or more types together. Aromatic tetracarboxylic acids are preferably 50% by mass or more, more preferably 60% by mass or more, still more preferably 70% by mass or more, and even more preferably 50% by mass or more of all tetracarboxylic acids, when importance is placed on heat resistance. Preferably it is 80 mass % or more.

As alicyclic tetracarboxylic acids for obtaining colorless and highly transparent polyimide, 1,2,3,4-cyclobutane tetracarboxylic acid, 1,2,3,4-cyclopentane tetracarboxylic acid, 3- (Carboxymethyl)cyclopentane-1,2,4-tricarboxylic 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]octo-7-ene-2,3,5,6-tetracarboxylic acid, tetradecahydroanthracene-2,3 ,6,7-tetracarboxylic acid, tetradecahydro-1,4:5,8:9,10-trimethanoanthracene-2,3,6,7-tetracarboxylic acid, decahydronaphthalene-2, 3,6,7-tetracarboxylic acid, decahydro-1,4:5,8-dimethanonaphthalene-2,3,6,7-tetracarboxylic acid, decahydro-1,4-ethano- 5,8-Methanonaphthalene-2,3,6,7-tetracarboxylic acid, norbonane-2-spiro-α-cyclopentanone-α'-spiro-2''-norbonane-5,5' ',6,6''-tetracarboxylic acid (aka "norbonane-2-spiro-2'-cyclopentanone-5'-spiro-2''-norbonane-5,5'',6,6 ''-tetracarboxylic acid'), methylnorbonane-2-spiro-α-cyclopentanone-α'-spiro-2''-(methylnorbornane)-5,5'',6,6'' -Tetracarboxylic acid, norbonane-2-spiro-α-cyclohexanone-α'-spiro-2''-norbonane-5,5'',6,6''-tetracarboxylic acid (aka " Norbonane-2-spiro-2'-cyclohexanone-6'-spiro-2''-norbonane-5,5'',6,6''-tetracarboxylic acid"), methylnorbornane-2 -Spiro-α-cyclohexanone-α'-spiro-2''-(methylnorbornane)-5,5'',6,6''-tetracarboxylic acid, norbonane-2-spiro-α- Cyclopropanone-α'-spiro-2''-norbonane-5,5'',6,6''-tetracarboxylic acid, norbonane-2-spiro-α-cyclobutanone-α'-spiro -2''-norbonane-5,5'',6,6''-tetracarboxylic acid, norbonane-2-spiro-α-cycloheptanone-α'-spiro-2''-norbonane- 5,5'',6,6 ''-tetracarboxylic acid, norbonane-2-spiro-α-cyclooctanone-α'-spiro-2''-norbonane-5,5'',6,6''-tetracarboxylic acid, Norbonane-2-spiro-α-cyclononanone-α'-spiro-2''-norbonane-5,5'',6,6''-tetracarboxylic acid, norbonane-2-spiro-α -Cyclodecanone-α'-spiro-2''-norbonane-5,5'',6,6''-tetracarboxylic acid, norbonane-2-spiro-α-cycloundecanone-α'- Spiro-2''-norbonane-5,5'',6,6''-tetracarboxylic acid, norbonane-2-spiro-α-cyclododecanone-α'-spiro-2''-norbonane -5,5'',6,6''-tetracarboxylic acid, norbonane-2-spiro-α-cyclotridecanone-α'-spiro-2''-norbonane-5,5'', 6,6''-tetracarboxylic acid, norbonane-2-spiro-α-cyclotetradecanone-α'-spiro-2''-norbonane-5,5'',6,6''-tetra Carboxylic acid, norbonane-2-spiro-α-cyclopentadecanone-α'-spiro-2''-norbonane-5,5'',6,6''-tetracarboxylic acid, norbonane- 2-spiro-α-(methylcyclopentanone)-α'-spiro-2''-norbonane-5,5'',6,6''-tetracarboxylic acid, norbonane-2-spiro-α Tetracarboxylic acids such as -(methylcyclohexanone)-α'-spiro-2''-norbornane-5,5'',6,6''-tetracarboxylic acid, and acid anhydrides thereof. can Among these, dianhydrides having two acid anhydride structures are suitable, particularly 1,2,3,4-cyclobutanetetracarboxylic dianhydride and 1,2,3,4-cyclohexanetetracarboxylic acid 2 Anhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride is preferred, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,4,5-cyclohexanetetra Carboxylic dianhydride is more preferred, and 1,2,3,4-cyclobutanetetracarboxylic dianhydride is still more preferred. Moreover, these may be used independently and may use 2 or more types together. Alicyclic tetracarboxylic acids are preferably 50% by mass or more, more preferably 60% by mass or more, still more preferably 70% by mass or more, of all tetracarboxylic acids, for example, when importance is placed on transparency. More preferably, it is 80 mass % or more.

Examples of tricarboxylic acids include trimellitic acid, 1,2,5-naphthalene tricarboxylic acid, diphenyl ether-3,3',4'-tricarboxylic acid, and diphenylsulfone-3,3',4 Aromatic tricarboxylic acids such as '-tricarboxylic acid, or hydrogenated products of the aromatic tricarboxylic acids such as hexahydrotrimellitic acid, ethylene glycol bistrimellitate, propylene glycol bistrimellitate, 1,4- alkylene glycol bistrimellitate such as butanediol bistrimellitate and polyethylene glycol bistrimellitate; and monohydrides and esterified products thereof. Among these, a monohydride having a single acid anhydride structure is preferable, and trimellitic anhydride and hexahydrotrimellitic anhydride are particularly preferable. In addition, these may be used individually or may be used combining plurality.

Examples of the dicarboxylic acids include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, orthophthalic acid, naphthalene dicarboxylic acid, biphenyl-4,4'-dicarboxylic acid, and 4,4'-oxydibenzenedicarboxylic acid. Hydrogenated products of aromatic dicarboxylic acids such as carboxylic acid, 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, or oxalic acid , succinic acid, glutalic acid, adipic acid, heptanedioic acid, octanedioic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, 2-methylsuccinic acid, and acid chlorides or esters thereof. . Among these, aromatic dicarboxylic acids and hydrogenated products thereof are suitable, and terephthalic acid, 1,4-cyclohexanedicarboxylic acid, and 4,4'-oxydibenzenedicarboxylic acid are particularly preferred. In addition, dicarboxylic acids may be used independently or may be used in combination of plurality.

Diamines or isocyanates for obtaining polyimide with high heat resistance and/or colorless transparency in the present invention are not particularly limited, and aromatic diamines and aliphatic diamines commonly used in polyimide synthesis or polyamideimide synthesis, Alicyclic diamines, aromatic diisocyanates, aliphatic diisocyanates, alicyclic diisocyanates and the like can be used. From the viewpoint of heat resistance, aromatic diamines or aromatic diisocyanates are preferred, and from the viewpoint of transparency, alicyclic diamines or alicyclic diisocyanates are preferred. In addition, when aromatic diamines or diisocyanates having a benzoxazole structure are used, they are preferable because they can exhibit a high modulus of elasticity, low heat shrinkage, and low coefficient of linear expansion along with high heat resistance. The said diamines and isocyanates may be used independently or may use 2 or more types together.

Examples of aromatic diamines include 2,2'-dimethyl-4,4'-diaminobiphenyl, 1,4-bis[2-(4-aminophenyl)-2-propyl]benzene, and 1,4- Bis (4-amino-2-trifluoromethylphenoxy) benzene, 2,2'-ditrifluoromethyl-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, 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, 3,3'-diaminodiphenylsulfoxide, 3,4'-diamino Diphenylsulfoxide, 4,4'-diaminodiphenylsulfoxide, 3,3'-diaminodiphenylsulfone, 3,4'-diaminodiphenylsulfone, 4,4'-diaminodiphenylsulfone, 3,3'-diaminobenzophenone, 3,4'-diaminobenzophenone, 4,4'-diaminobenzophenone, 3,3'-diaminodiphenylmethane, 3,4'-diaminodiphenyl Methane, 4,4'-diaminodiphenylmethane, bis[4-(4-aminophenoxy)phenyl]methane, 1,1-bis[4-(4-aminophenoxy)phenyl]ethane, 1,2 -bis[4-(4-aminophenoxy)phenyl]ethane, 1,1-bis[4-(4-aminophenoxy)phenyl]propane, 1,2-bis[4-(4-aminophenoxy) Phenyl]propane, 1,3-bis[4-(4-aminophenoxy)phenyl]propane, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 1,1-bis[4- (4-aminophenoxy)phenyl]butane, 1,3-bis[4-(4-aminophenoxy)phenyl]butane, 1,4-bis[4-(4-aminophenoxy)phenyl]butane, 2 ,2-bis[4-(4-aminophenoxy)phenyl]butane, 2,3-bis[4-(4-aminophenoxy)phenyl]butane, 2-[4- (4-aminophenoxy)phenyl]-2-[4-(4-aminophenoxy)-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-amino) Phenoxy) -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-amino Phenoxy)biphenyl, bis[4-(4-aminophenoxy)phenyl]ketone, bis[4-(4-aminophenoxy)phenyl]sulfide, bis[4-(4-aminophenoxy)phenyl] Sulfoxide, bis[4-(4-aminophenoxy)phenyl]sulfone, bis[4-(3-aminophenoxy)phenyl]ether, bis[4-(4-aminophenoxy)phenyl]ether, 1, 3-bis[4-(4-aminophenoxy)benzoyl]benzene, 1,3-bis[4-(3-aminophenoxy)benzoyl]benzene, 1,4-bis[4-(3-aminophenoxy) ) Benzoyl] benzene, 4,4'-bis [(3-aminophenoxy) benzoyl] benzene, 1,1-bis [4- (3-aminophenoxy) phenyl] propane, 1,3-bis [4- (3-aminophenoxy)phenyl]propane, 3,4'-diaminodiphenylsulfide, 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]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, 1,3-bis[4-(4-amino-6-cyanophenoxy) -α,α-dimethylbenzyl]benzene, 3,3'-diamino-4,4'-diphenoxybenzophenone, 4,4'-diamino-5,5'-diphenoxybenzophenone, 3, 4'-diamino-4,5'-diphenoxybenzophenone, 3,3'-diamino-4-phenoxybenzophenone, 4,4'-diamino-5-phenoxybenzophenone, 3,4 '-diamino-4-phenoxybenzophenone, 3,4'-diamino-5'-phenoxybenzophenone, 3,3'-diamino-4,4'-dibiphenoxybenzophenone, 4,4 '-diamino-5,5'-dibiphenoxybenzophenone, 3,4'-diamino-4,5'-dibiphenoxybenzophenone, 3,3'-diamino-4-biphenoxybenzophenone , 4,4'-diamino-5-biphenoxybenzophenone, 3,4'-diamino-4-biphenoxybenzophenone, 3,4'-diamino-5'-biphenoxybenzophenone, 1,3-bis(3-amino-4-phenoxybenzoyl)benzene, 1,4-bis(3-amino-4-phenoxybenzoyl)benzene, 1,3-bis(4-amino-5-phenoxy Benzoyl) benzene, 1,4-bis (4-amino-5-phenoxybenzoyl) benzene, 1,3-bis (3-amino-4-biphenoxybenzoyl) benzene, 1,4-bis (3-amino -4-biphenoxybenzoyl) benzene, 1,3-bis (4-amino-5-biphenoxybenzoyl) benzene, 1,4-bis (4-amino-5-biphenoxybenzoyl) benzene, 2, 6-bis[4-(4-aminoα,α-dimethylbenzyl)phenoxy]benzonitrile, 4,4′-[spiro(xanthene-9,9′-fluorene)-2,6-diylbis( oxycarbonyl)] bisaniline, 4,4'-[spiro(xanthen-9,9'-fluorene)-3,6-diylbis(oxycarbonyl)]bisaniline, and the like. Further, some or all of the hydrogen atoms on the aromatic ring of the aromatic diamine may be substituted with a halogen atom, an alkyl group or alkoxyl group having 1 to 3 carbon atoms, or a cyano group, or an alkyl group or alkoxyl group having 1 to 3 carbon atoms. Some or all of the hydrogen atoms of may be substituted with halogen atoms. Moreover, aromatic diamines may be used individually or may be used combining plurality.

In addition, the aromatic diamine having the benzoxazole structure is not particularly limited, and examples thereof include 5-amino-2-(p-aminophenyl)benzoxazole and 6-amino-2-(p-aminophenyl)benzo. Oxazole, 5-amino-2-(m-aminophenyl)benzoxazole, 6-amino-2-(m-aminophenyl)benzoxazole, 2,2'-p-phenylenebis(5-aminobenzo oxazole), 2,2'-p-phenylenebis(6-aminobenzoxazole), 1-(5-aminobenzooxazolo)-4-(6-aminobenzooxazolo)benzene, 2,6- (4,4'-diaminodiphenyl)benzo[1,2-d:5,4-d']bisoxazole, 2,6-(4,4'-diaminodiphenyl)benzo[1,2 -d:4,5-d']bisoxazole, 2,6-(3,4'-diaminodiphenyl)benzo[1,2-d:5,4-d']bisoxazole, 2, 6-(3,4'-diaminodiphenyl)benzo[1,2-d:4,5-d']bisoxazole, 2,6-(3,3'-diaminodiphenyl)benzo[1 ,2-d:5,4-d']bisoxazole, 2,6-(3,3'-diaminodiphenyl)benzo[1,2-d:4,5-d']bisoxazole, etc. can be heard Among these, in particular, 2,2'-ditrifluoromethyl-4,4'-diaminobiphenyl, 4-amino-N-(4-aminophenyl)benzamide, 4,4'-diaminodiphenyl Sulfone or 3,3'-diaminobenzophenone is preferred. Moreover, aromatic diamines which have an oxazole structure may be used independently or may be used combining plurality.

Examples of alicyclic diamines include 1,4-diaminocyclohexane, 1,4-diamino-2-methylcyclohexane, 1,4-diamino-2-ethylcyclohexane, and 1,4-diamino. -2-n-propylcyclohexane, 1,4-diamino-2-isopropylcyclohexane, 1,4-diamino-2-n-butylcyclohexane, 1,4-diamino-2-isobutylcyclo Hexane, 1,4-diamino-2-sec-butylcyclohexane, 1,4-diamino-2-tert-butylcyclohexane, 4,4'-methylenebis(2,6-dimethylcyclohexylamine), Cyclohexane-1,4-diyl dimethaneamine, bicyclo[2,2,1]heptane-2,5-diamine, etc. are mentioned. Among these, 1,4-diaminocyclohexane or 1,4-diamino-2-methylcyclohexane is particularly preferred, and 1,4-diaminocyclohexane is more preferred. Moreover, alicyclic diamines may be used independently or may be used combining plurality.

Diisocyanates include, for example, 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'-di Isocyanate, diphenylmethane-4,4'-diisocyanate, diphenylmethane-3,3'-diisocyanate, diphenylmethane-3,4'-diisocyanate, diphenylether-4,4'-diisocyanate, Benzophenone-4,4'-diisocyanate, diphenylsulfone-4,4'-diisocyanate, tolylene-2,4-diisocyanate, tolylene-2,6-diisocyanate, m-xylylene diisocyanate, p-xylylenediisocyanate, naphthalene-2,6-diisocyanate, 4,4'-(2,2-bis(4-phenoxyphenyl)propane)diisocyanate, 3,3'- or 2,2'- Dimethylbiphenyl-4,4'-diisocyanate, 3,3'- or 2,2'-diethylbiphenyl-4,4'-diisocyanate, 3,3'-dimethoxybiphenyl-4,4' -Aromatic diisocyanates such as diisocyanate and 3,3'-diethoxybiphenyl-4,4'-diisocyanate, and diisocyanates obtained by hydrogenating any of these diisocyanates (e.g., isophorone diisocyanate, 1,4 -Cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, hexamethylene diisocyanate) and the like. Among these, diphenylmethane-4,4'-diisocyanate, tolylene-2,4-diisocyanate, tolylene-2,6-diisocyanate, 3, tolylene-2,4-diisocyanate, 3, 3'-dimethylbiphenyl-4,4'-diisocyanate, naphthalene-2,6-diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, or 1,4-cyclohexane diisocyanate is preferred. In addition, diisocyanates may be used independently or may be used in combination of plurality.

The solvent used in the polyamic acid solution, polyimide solution and polyamideimide solution of the present invention is not particularly specified as long as it dissolves the polyimide resin or its precursor, but for example, N-methyl-2-pyrrolidone; N,N-dimethylacetamide, N,N-dimethylformamide, 1,3-dimethyl-2-imidazolidinone, tetramethylurea, sulfolane, dimethylsulfoxide, γ-butyrolactone, cyclohexanone, and cyclopentanone. These may be used independently and may use 2 or more types together. In particular, considering productivity and optical properties of the film, it is preferable to use N,N-dimethylacetamide as the main component of the organic solvent. In addition to these organic solvents, poor solvents such as toluene and xylene may be used to the extent that the polyimide-based resin or its precursor does not precipitate.

The thickness of the polyimide film in the present invention is preferably 3 μm or more, more preferably 11 μm or more, still more preferably 24 μm or more. The upper limit of the thickness of the polyimide film is not particularly limited, but for use as a flexible electronic device, it is preferably 250 μm or less, more preferably 150 μm or less, still more preferably 100 μm or less.

The tensile modulus of elasticity of the polyimide film of the present invention is required to be 3 GPa or more in both MD and TD directions, preferably 4 GPa or more, and more preferably 5 GPa or more. When the tensile modulus is 3 GPa or more, peeling between the polyimide film and the functional element can be avoided, and the handleability is excellent. The tensile modulus of elasticity in both the MD and TD directions is preferably 20 GPa or less, more preferably 12 GPa or less, still more preferably 10 GPa or less. If the said tensile modulus is 20 GPa or less, the said polyimide film can be used as a flexible film. In addition, the tensile modulus of elasticity of the polyimide film refers to the average value of the tensile modulus of elasticity in the flow direction (MD direction) and the tensile modulus of elasticity in the width direction (TD direction) of the polyimide film. The method for measuring the tensile modulus of elasticity of the polyimide film is based on the method described in Examples.

The average CTE between 30°C and 300°C of the polyimide film in the present invention is required to be -5 ppm/°C to +55 ppm/°C. Preferably -4 ppm/°C to +45 ppm/°C, more preferably -3 ppm/°C to +35 ppm/°C, still more preferably -2 ppm/°C to +20 ppm/°C, Even more preferably, it is +1 ppm/°C to +10 ppm/°C. When the CTE is within the above range, the difference in coefficient of linear expansion with the functional element can be kept small, and separation between the polyimide film and the functional element can be avoided even when subjected to a heat application process, resulting in excellent workability. Here, CTE is a factor representing reversible expansion and contraction with respect to temperature. In addition, the CTE of the said polyimide film refers to the average value of CTE of the flow direction (MD direction) of a polyimide film, and CTE of the width direction (TD direction). The method for measuring the CTE of the polyimide film is based on the method described in Examples.

The polyimide film exhibiting the tensile modulus and CTE of the present invention can be realized by stretching in the film forming process of the polyimide film. In this stretching operation, the polyimide solution is applied to a support for production of a polyimide film and dried to obtain a polyimide film containing 1 to 50% by mass of a solvent, and then peeled on or from the support for production of a polyimide film. It can be realized by stretching a polyimide film containing 1 to 50% by mass of a solvent at a high temperature and drying it, by stretching it from 1.5 times to 4.0 times in the MD direction and from 1.4 times to 3.0 times in the TD direction. At this time, an unstretched thermoplastic polymer film is used as a support for producing a polyimide film, the thermoplastic polymer film and the polyimide film are simultaneously stretched, and then the stretched polyimide film is separated from the thermoplastic polymer film, particularly in the MD direction. Damage to the polyimide film at the time of application can be prevented, and a higher quality, colorless and transparent polyimide film can be obtained. The preferred stretch ratio in the MD direction is 1.7 to 3.5 times, more preferably 2.0 to 3.0 times. In addition, the preferred draw ratio in the TD direction is 1.7 to 3.5 times, more preferably 2.0 to 3.0 times. The ratio of the draw ratio in the MD direction to the draw ratio in the TD direction (MD/TD) is preferably greater than 1, more preferably 1.01 or more, still more preferably 1.05 or more, still more preferably 1.08 or more. , and is particularly preferably 1.1 or more. Further, it is preferably 2.0 or less, more preferably 1.8 or less, still more preferably 1.5 or less, and particularly preferably 1.2 or less.

The solvent content of the polyimide film of the present invention needs to be 0.5 to 5.0% by mass. It is preferably in the range of 0.7 to 4.0% by mass, more preferably in the range of 1.0 to 3.0% by mass. By setting the solvent content to the above lower limit or more, the surface of the polyimide film does not become excessively inactive due to excessive high-temperature treatment, and adhesion to the polymer composition forming the self-healing layer described later is maintained, and yellow Deterioration of the index can be suppressed. Further, by setting the solvent content to the above upper limit or less, it becomes easy to set the tensile modulus and CTE within a preferable range, and whitening and devitrification due to transfer of residual solvent to the self-healing layer are suppressed, and light at a wavelength of 400 nm is suppressed. Deterioration of transmittance or total light transmittance can be suppressed.

The solvent contained in the polyimide film may be a residue (residual solvent) of the solvent in the polyimide film production process (eg, a process of drying the polyimide film by treating it at a high temperature), and the solvent after the polyimide film is produced. It doesn't matter if you added . Preferably, it is a residual solvent in the polyimide film manufacturing process.

Drying conditions for the polyimide film and/or green film are not particularly limited, and may be dried in one step or in multiple steps. Drying in multiple stages is preferred. The number of drying stages in multi-stage drying is not particularly limited, and is preferably two or more stages, and more preferably three or more stages. Moreover, it is preferable that it is 10 steps or less, More preferably, it is 5 steps or less. It is preferable to make the drying temperature in a multi-stage higher as it becomes the next stage. For example, in the case of two-step drying, the first step is preferably 100°C or more and 250°C or less, more preferably 120°C or more and 200°C or less, and still more preferably 150°C or more and 180°C or less. In the second stage, it is preferably more than 250°C and less than 500°C, more preferably more than 280°C and less than 450°C, and still more preferably more than 300°C and less than 400°C.

In addition, the drying time can be set according to the said drying temperature, film thickness, the kind of solvent, and the drying apparatus used. For example, in the case of the two-step drying using a tenter, the drying time of the first step is preferably 2 minutes or more and 15 minutes or less, more preferably 3 minutes or more and 12 minutes or less, and still more preferably 5 minutes or more less than 8 minutes The drying time in the second step is preferably more than 1 minute and 10 minutes or less, more preferably 2 minutes or more and 8 minutes or less, still more preferably 3 minutes or more and 5 minutes or less. By setting it in the said range, the solvent content of a polyimide film can be made into a predetermined range.

Further, in the case of three-stage drying, the first stage is preferably 100°C or more and 200°C or less, more preferably 120°C or more and 190°C or less, and still more preferably 150°C or more and 180°C or less. In the second step, it is preferably more than 200°C and not more than 300°C, more preferably 210°C or more and 280°C or less, still more preferably 220°C or more and 250°C or less. The third step is preferably more than 300°C and less than 500°C, more preferably more than 320°C and less than 450°C, still more preferably more than 340°C and less than 400°C. In addition, the drying time can be set according to the drying temperature. For example, in the case of the three-step drying, the drying time of the first step is preferably 30 seconds or more and 10 minutes or less, more preferably 1 minute or more and 8 minutes or less, and still more preferably 2 minutes or more and 5 minutes or less. . The drying time in the second step is preferably 30 seconds or more and 10 minutes or less, more preferably 1 minute or more and 8 minutes or less, still more preferably 2 minutes or more and 5 minutes or less. The drying time in the third step is preferably more than 1 minute and less than 10 minutes, more preferably 2 minutes or more and 9 minutes or less, still more preferably 3 minutes or more and 8 minutes or less. By setting it in the said range, the solvent content of a polyimide film can be made into a predetermined range.

In the laminate of the present invention, a self-healing layer is laminated on at least one side of the polyimide film exhibiting the tensile modulus and CTE, and thereby the self-healing property of the laminate is secured.

- Definition of self-healing -

Here, the self-healing property refers to the property of restoring deformation or damage caused by distortion due to stress concentration when the stress load is removed. Specifically, by the "recovery rate" obtained by the measurement method described in the examples It is evaluated.

The laminate of the present invention has self-healing properties, and the recovery rate calculated by measuring the recovery rate is preferably 80% or more, more preferably 85% or more, more preferably 90% or more, and 95% or more It is even more preferable, and 100% is particularly preferable.

Since the self-healing layer constituting the laminate of the present invention is mainly formed on the front surface of an image display device, it has a crosslinking point from the viewpoint of requiring low tack, antifouling, and chemical resistance, and also has self-healing properties. From the viewpoint of achieving a return ratio of 80% or more, it is preferable that part or all of the crosslinking points are a polymer composition (hereinafter also referred to as "self-healing polymer composition") containing movable crosslinking points.

The movable cross-linking point in the present invention represents a cross-linking point formed by a chemical bond other than a covalent bond as a first form, and an ionic bond or a hydrogen bond is exemplified as a chemical bond other than a covalent bond. When distortion caused by stress concentration propagates, these chemical bonds break and cause deformation or damage. However, since the bond is regenerated by molecular motion after the stress is removed, the deformation or damage disappears and exhibits self-healing properties. have

The movable cross-linking point in the present invention represents a cross-linking point consisting of constraints by geometric shapes that do not depend on chemical bonds as a second form, and in the constraints by geometric shapes, straight-chain molecules are formed at the openings of cyclic molecules. There are constraints that pass through, and constraints in which ring-shaped molecules pass through openings. When the distortion caused by stress concentration propagates, the constraint points move instead of breaking the molecular bonds, resulting in deformation or loss. Damage is lost and it has self-healing properties.

As the crosslinking point having mobility in the present invention, the polymer composition having a crosslinking point formed by a chemical bond other than a covalent bond, which is the first form, is a polymer composition using an ionic bond, such as a metal ion-containing ethylene acrylate copolymer, a metal ion (meth)acrylate-containing ethylene copolymers, metal ion-containing sulfonic acid polyester polymers, and metal ion-containing sulfonic acid polyester polyether copolymers, as polymer compositions utilizing hydrogen bonds, polyetherurethane copolymers and aliphatic polyesterurethanes. copolymers, polyether polyester urethane copolymers, polyurethane acrylate copolymers, polyether polyamide copolymers, and aliphatic polyester polyamide copolymers.

As the crosslinking point having mobility in the present invention, the polymer composition having a crosslinking point composed of constraints by the geometric shape, which is the second type, is a cyclic polyether ring piercing polyether polymer, a cyclic polyether ring piercing aliphatic polyester copolymer polymers, cyclic polyether penetrating polyacryl polymers, cyclodextrin penetrating polyether polymers, and cyclodextrin penetrating aliphatic polyester copolymers.

The content of the self-healing polymer composition contained in the self-healing layer is preferably 90% by mass or more, more preferably 95% by mass or more, even more preferably 99% by mass or more, and particularly preferably 99.9% by mass. It is % or more, and even if it is 100 mass %, there is no problem.

The polymer composition, in which some or all of the crosslinking points contain a crosslinking point having mobility, may be used alone or in combination of a plurality of them, and, if necessary, a solvent, a softener, a plasticizer, an antiaging agent, an antioxidant, an ultraviolet absorber , light stabilizers, surface lubricants, leveling agents, antifouling agents, release agents, heat stabilizers, lubricants, inorganic fine particles, surfactants, and the like, additives commonly used in the art to which the present invention pertains may be further included. In addition, the content can be variously adjusted within the range of not deteriorating the physical properties of the laminate of the present invention, so there is no particular limitation, but, for example, it is included in about 0.1 to about 10 parts by mass based on 100 parts by mass of the self-healing layer. It may be.

The thickness of the self-healing layer constituting the laminate of the present invention is preferably 5 μm or more, more preferably 8 μm or more, and more preferably 10 μm or more, from the viewpoint of securing adhesion and sufficiently expressing the self-healing function. particularly preferred. On the other hand, from the viewpoint of ensuring transparency, workability and moldability, the upper limit of the thickness is preferably 100 μm or less, more preferably 80 μm or less, and particularly preferably 50 μm or less.

The self-healing layer constituting the laminate of the present invention can be formed by applying a self-healing polymer composition on a polyimide film, drying it as necessary, and then curing it by irradiating heat or active energy rays. . That is, the self-healing polymer composition for forming such a self-healing layer in the present invention is preferably a thermosetting polymer composition or an active energy ray-curable polymer composition.

As a coating method used for coating the self-healing polymer composition, a wet coating method is preferred. Examples of such a wet coating method include a reverse coating method, a spray coating method, a bar coating method, a gravure coating method, a rod coating method, a die coating method, a roll coating method, and a lip coating method.

The thickness of the laminate is preferably 8 μm or more, more preferably 15 μm or more, still more preferably 20 μm or more. Further, it is preferably 300 μm or less, more preferably 200 μm or less, and still more preferably 100 μm or less.

In the laminate of the present invention, a polyimide film and a self-healing layer are laminated in this order, and the self-healing layer has adhesion to the polyimide film, and the adhesion can be specifically obtained by the measurement method described in the Examples. It is evaluated by "attachment rate".

As the adhesiveness of the self-healing layer of the laminate of the present invention, the adhesion rate is preferably 80% or more, more preferably 85% or more, still more preferably 90% or more, still more preferably 95% or more, and 100% or more. % is particularly preferred. As described above, the adhesion rate can achieve a desirable value by setting the solvent content in the polyimide film to the lower limit value or more. In addition, the polyimide film may be subjected to corona treatment, plasma treatment, ozone treatment, chemical treatment, solvent treatment, etc. as a pretreatment on the surface within a range that does not reduce the transparency or adhesion to the self-healing layer.

Since the laminate of the present invention is mainly used around the front plate and electrodes of image display devices such as touch panels and displays, the yellowness index (yellow index) is preferably 10 or less, more preferably 7 or less, and even more Preferably it is 5 or less, More preferably, it is 3 or less. The lower limit of the yellowness 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, still more preferably 0.3 or more.

Since the laminate of the present invention is mainly used around the front plate and electrodes of image display devices such as touch panels and displays, the light transmittance at a wavelength of 400 nm is preferably 70% or more, more preferably 72% or more, , More preferably, it is 75% or more, and even more preferably, it is 80% or more. The upper limit of the light transmittance of the polyimide film at a wavelength of 400 nm is not particularly limited, but for use as a flexible electronic device, it is preferably 99% or less, more preferably 98% or less, still more preferably 97% or less. .

Since the laminate of the present invention is mainly used around the front plate and electrodes of image display devices such as touch panels and displays, the total light transmittance is preferably 85% or more, more preferably 86% or more, still more preferably It is 87% or more, and more 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 99% or less, more preferably 98% or less, still more preferably 97% or less.

Example

Hereinafter, the present invention will be described in detail using Examples, but the present invention is not limited to the following Examples unless departing from the gist thereof.

On the other hand, each measured value in Examples and Comparative Examples was measured by the following method unless otherwise noted.

<Reduced viscosity of polyamic acid and polyimide>

A solution dissolved in N-methyl-2-pyrrolidone (or N,N-dimethylacetamide) to a polymer concentration of 0.2 g/dl was measured at 30°C with an Uberode viscometer. (When the solvent used to prepare the polyamic acid solution was N,N-dimethylacetamide, the measurement was performed by dissolving the polymer using N,N-dimethylacetamide.)

<Thickness of polyimide film and laminate>

It was measured using a micrometer (Militron 1245D, manufactured by Fine Lupe Co., Ltd.).

<Tensile modulus of elasticity of polyimide film>

What was cut into segments of 100 mm x 10 mm in the flow direction (MD direction) and width direction (TD direction) of the polyimide film, respectively, was used as a test piece. The test piece was cut out from the central part in the width direction. Using a tensile tester (manufactured by Shimadzu Corporation, Autograph (R), model name AG-5000A), 5 samples each in the MD direction and the TD direction under the conditions of a temperature of 25 ° C, a tensile speed of 50 mm / min, and a distance between chucks of 40 mm. The tensile elastic modulus was measured, and the average value of all the measured values was obtained.

<Coefficient of linear expansion (CTE) of polyimide film>

Stretching ratio was measured at 5 samples each in the flow direction (MD direction) and width direction (TD direction) of the polyimide film under the following conditions, and at 15 ° C intervals such as 30 ° C to 45 ° C and 45 ° C to 60 ° C. Stretching ratio/temperature was measured, this measurement was performed up to 300°C, and the average value of all measured values was calculated as CTE.

Device name: TMA4000S manufactured by MAC Science

Sample length: 20 mm

Sample width: 2 mm

Heating start temperature: 25°C

Heating end temperature: 400℃

Heating rate: 5°C/min

Atmosphere: Argon

<Solvent content in polyimide film>

The solvent content in the polyimide film was measured using a thermogravimetric analyzer (manufactured by TA Instruments, model name TGA2950). About 10 mg of the sample was set in an aluminum microcell, and the temperature was raised to 500°C at a rate of 5°C/min. The measurement was performed in a nitrogen atmosphere, and the weight decreased between 100°C and 300°C was used as the solvent content.

<Return rate of laminated body>

Using a micro hardness tester Fischer Scope HM2000 (manufactured by Fisher Co., Ltd.) as a measuring device, the laminate was fixed to a slide glass with instant adhesive Aaron Alpha 221F (manufactured by Toagosei Co., Ltd.), and set in the measuring device. A load was applied over 15 seconds to 0.5 mN from a Vickers square pyramid diamond indenter at a measurement temperature of 30 DEG C to the laminated body fixed to the slide glass, and held at 0.5 mNd for 5 seconds. The maximum displacement at that time is (h1). Thereafter, the load was removed to 0.005 mN over 15 seconds, and the displacement when held at 0.005 mN for 60 seconds was (h2), and the return rate [{(h1-h2)/h1} × 100 (%)] Calculated.

<Evaluation of the flexibility of the laminate>

Based on the bending test method conforming to JIS K 5600-5-1 (1999), a bending test of 1000 times was performed using a bending tester type 1 (manufactured by Imoto Manufacturing Co., Ltd., model IMC-AOF2, mandrel diameter φ20 mm) After that, the surface of the laminate sample was visually observed, and flexibility was evaluated according to the following criteria.

0: No minute cracks are observed on the surface of the laminate sample

×: Minor cracks are observed on the surface of the laminate sample

<Adhesion rate of laminated body>

By the crosscut method of JIS K 5600-5-6 (1999), under constant temperature and humidity conditions (23 ° C., 50% RH), on the self-healing layer of the laminate sample, a crosscut peel test jig was used to perform a longitudinal test. 100 crosscuts of 1 square mm were produced by inserting 11 straight cuts at intervals of 1 mm in the direction and transverse direction, respectively. On this crosscut square, adhesive tape No. 252 manufactured by Sekisui Chemical Industry Co., Ltd. is adhered thereon, and after pressing uniformly using a spatula, the adhesive tape is peeled in the direction of 90 degrees with respect to the layered product. The adhesion rate can be obtained as the remaining number of self-healing layer crosscuts on the polyimide film. For evaluation, the remaining number out of 100 was determined as "%".

<Yellowness Index (Yellow Index, YI) of Laminates>

Using a color meter (ZE6000, manufactured by Nippon Denshoku Co., Ltd.) and a C2 light source, the tristimulus value XYZ value of the polyimide film was measured according to ASTM D1925, and the yellowness index (YI) was calculated by the following formula. On the other hand, the same measurement was performed three times and the arithmetic average value was adopted.

YI=100×(1.28X-1.06Z)/Y

<400 nm light transmittance of the laminate>

The light transmittance at a wavelength of 400 nm was measured using a spectrophotometer ("U-2001" manufactured by Hitachi, Ltd.), and the obtained value was converted to a thickness of 20 µm as according to Runbelt-Vale's law, and the obtained value was The transmittance of mid-film was 400 nm. In addition, the same measurement was performed three times and the arithmetic average value was adopted.

<Total light transmittance (TT) of the laminate>

The total light transmittance (TT) of the polyimide film was measured using HAZEMETER (NDH5000, manufactured by Nippon Denshoku Co., Ltd.). A D65 lamp was used as the light source. In addition, the same measurement was performed three times and the arithmetic average value was adopted.

[Preparation of polyamic acid solution A]

After purging the inside of the reaction vessel equipped with a nitrogen inlet tube, thermometer, and stirring rod with nitrogen, 176.5 g (0.900 mol) of 1,2,3,4-cyclobutanetetracarboxylic dianhydride was added to the reaction vessel under a nitrogen atmosphere. (CBDA), 31.0 g (0.100 mol) of 4,4'-oxydiphthalic acid (ODPA), 160.1 g (0.500 mol) of 2,2'-ditrifluoromethyl-4,4'-diaminobiphenyl (TFMB), 113.6 g (0.500 mol) of 4-amino-N- (4-aminophenyl) benzamide (DABAN), and 2000 g of N, N-dimethylacetamide were added and dissolved, followed by stirring at room temperature for 24 hours A polymerization reaction was performed. Then, it was diluted with 1000 g of N,N-dimethylacetamide to obtain a polyamic acid solution A having a reduced viscosity of 4.50 dl/g.

[Preparation of Polyimide Solution B]

After purging the inside of the reaction vessel equipped with a nitrogen inlet pipe, thermometer, and stirring rod with nitrogen, 461 g of N,N-dimethylacetamide (DMAC) and 64.0 g (0.200 mol) of 2, 2'-ditrifluoromethyl-4,4'-diaminobiphenyl (TFMB) was added and stirred, and TFMB was dissolved in DMAC. Then, 89.737 g (0.202 mol) of 4,4'-(2,2-hexafluoroisopropylidene)diphthalic dianhydride (6FDA) was added over 10 minutes under a nitrogen stream while stirring the inside of the reaction vessel. After adding, the polymerization reaction was carried out by continuously stirring for 6 hours while adjusting the temperature as it was to be in the temperature range of 20 to 40°C, and a viscous polyamic acid solution was obtained.

Next, after diluting by adding 410 g of DMAC to the obtained polyamic acid solution, 25.83 g of isoquinoline was added as an imidation accelerator, and the polyamic acid solution was maintained at a temperature range of 30 to 40 ° C. while stirring, there As an imidation agent, 122.5 g (1.20 mol) of acetic anhydride was slowly added dropwise over about 10 minutes, and then the liquid temperature was maintained at 30 to 40° C. and stirred continuously for 12 hours to further carry out a chemical imidation reaction. Mead solution was obtained.

Next, 1000 g of the obtained polyimide solution containing the imidation agent and the imidation accelerator was transferred to a reaction vessel equipped with a stirring device and a stirring blade, and maintained at a temperature of 15 to 25 ° C. while stirring at a speed of 120 rpm, , 1500 g of methanol was added dropwise thereto at a rate of 10 g/min. It was confirmed that the polyimide solution became cloudy at the point where about 800 g of methanol was injected, and precipitation of powdery polyimide was confirmed. Subsequently, 1500 g of methanol was injected to complete the precipitation of polyimide. Subsequently, the contents of the reaction vessel were separated by filtration with a suction filtration device, and further washed and filtered using 1000 g of methanol. Thereafter, 50 g of the polyimide powder separated by filtration was dried at 50° C. for 24 hours using a dryer equipped with a local exhaust system and further dried at 260° C. for 2 hours to remove remaining volatile components, and polyimide powder was obtained. The reduced viscosity of the obtained polyimide powder was 5.40 dl/g. Next, 40 g of the obtained polyimide powder was dissolved in 300 g of DMAC to obtain a polyimide solution B.

[Preparation of polyimide solution C]

120.5 g (0.485 mol) of 4,4'-diaminodiphenylsulfone (4,4' -DDS), 51.6 g (0.208 mol) of 3,3'-diaminodiphenylsulfone (3,3'-DDS), and 500 g of γ-butyrolactone (GBL) were added. Subsequently, after adding 217.1 g (0.700 mol) of 4,4'-oxydiphthalic dianhydride (ODPA), 223 g of GBL, and 260 g of toluene at room temperature, the internal temperature was raised to 160°C, and the temperature was raised to 160°C for 1 hour. Imidization was performed by heating to reflux. After completion of the imidation, the temperature was raised to 180°C, and the reaction was continued while extracting toluene. After the polymerization reaction for 12 hours, the oil bath was removed, the temperature was returned to room temperature, and GBL was added so that the solid content was 20% by mass to obtain a polyimide solution C having a reduced viscosity of 2.50 dl/g.

[Preparation of polyamic acid solution G]

After purging the inside of the reaction vessel equipped with a nitrogen inlet tube, thermometer, and stirring rod with nitrogen, 94.1 g (0.480 mol) of 1,2,3,4-cyclobutanetetracarboxylic dianhydride was added to the reaction vessel under a nitrogen atmosphere. (CBDA), 108.9 g (0.370 mol) of 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA), 46.5 g (0.150 mol) of 4,4'-oxydiphthalic acid (ODPA) ), 320.2 g (1.000 mol) of 2,2'-ditrifluoromethyl-4,4'-diaminobiphenyl (TFMB), and 2000 g of N, N-dimethylacetamide were added and dissolved, followed by dissolution at room temperature. was stirred for 24 hours to carry out a polymerization reaction. Then, it was diluted with 1000 g of N,N-dimethylacetamide to obtain a polyamic acid solution G having a reduced viscosity of 3.50 dl/g.

[Production Example 1 of Polyimide Film]

Polyamic acid solution A was applied using a die coater onto a mirror-finished stainless steel endless continuous belt (coating width: 1240 mm) as a film production support, and dried at 90 to 115° C. for 10 minutes. After drying, the self-supporting polyamic acid film (containing 9% by mass of residual solvent) was peeled off from the support and both ends were cut to obtain a green film. The obtained green film was conveyed by a pin tenter so that the final pin sheet interval was 1140 mm, heat treatment was performed at 170 ° C. for 2 minutes in the first step, 230 ° C. for 2 minutes in the second step, and 350 ° C. for 6 minutes in the third step. It was removed to be within the range of values. Thereafter, it was cooled to room temperature for 2 minutes, and portions with poor flatness at both ends of the film were cut out with a slitter and wound into a roll shape to obtain a polyimide film 1A shown in Table 1. Polyimide film 1B or polyimide film 1G shown in Table 1 was obtained by changing the polyamic acid solution A to polyimide solution B or polyamic acid solution G in the same manner and changing the coating thickness to the support.

[Production Example 2 of Polyimide Film]

Polyamic acid solution A was coated on the surface with a surface roughness (Sa) of 1 nm, a maximum protrusion height (Sp) of 7 nm, a peak point density (Spd) of 20/square μm or less, and It was applied to a non-layered polyester film using a comma coater (coating width: 1240 mm), and dried at 90 to 115° C. for 10 minutes. After drying, the self-supporting polyamic acid film (containing 10% by mass of residual solvent) was peeled off from the support and both ends were cut to obtain a green film. The obtained green film was conveyed by a pin tenter so that the final pin sheet interval was 1140 mm, heat treatment was performed at 170 ° C. for 2 minutes in the first step, 230 ° C. for 2 minutes in the second step, and 350 ° C. for 6 minutes in the third step. It was removed to be within the range of values. Thereafter, it was cooled to room temperature for 2 minutes, and portions with poor flatness at both ends of the film were cut out with a slitter, and wound into a roll shape to obtain a polyimide film 2A shown in Table 1. Polyimide film 2C or polyimide film 2G shown in Table 1 was obtained by changing the polyamic acid solution A to polyimide solution C or polyamic acid solution G in the same manner and changing the coating thickness to the support.

[Production Example 3 of Polyimide Film]

Polyimide solution B was applied to an unstretched polypropylene film having a surface roughness (Sa) of 3 nm, a maximum protrusion height (Sp) of 12 nm, and a peak point density (Spd) of 25/square μm or less at the points of the film production support. It was applied using a comma coater (coating width: 450 mm) and dried at 85 to 105° C. for 30 minutes to obtain a two-layer film of a support and a polyimide film (including about 8% by mass of residual solvent). Next, this two-layer film was stretched 2.8 times in the MD direction using the difference in circumferential speed of the rolls at the same time. Moreover, between the rolls with the circumferential speed difference, it arrange|positioned so that a roll might not contact the surface of the polyimide film side of a two-layer film. After stretching in the MD direction, both ends of the two-layer film are held by a clip tenter, and transported while heat treatment at 150 ° C. for 6 minutes so that the final pin sheet interval is 1140 mm, that is, stretched 2.5 times in the TD direction, After that, the polyimide film was peeled off from the support of the two-layer film, and a heat treatment at 350° C. for 3 minutes was further performed to remove the residual solvent so as to be within a predetermined range. Thereafter, it was cooled to room temperature for 2 minutes, and portions with poor flatness at both ends of the film were cut out with a slitter, and rolled up to obtain a polyimide film 3B shown in Table 1. In the same manner, polyimide solution B was replaced with polyimide solution C, and the coating thickness to the support was changed to obtain a polyimide film 3C shown in Table 1.

[Production Example 4 of Polyimide Film]

Polyamic acid solution A was applied using a die coater onto a mirror-finished stainless steel endless continuous belt (coating width: 1240 mm) as a film production support, and dried at 90 to 115° C. for 10 minutes. After drying, the self-supporting polyamic acid film (containing 9% by mass of residual solvent) was peeled off from the support and both ends were cut to obtain a green film. The obtained green film was conveyed by a pin tenter so that the final pin sheet interval was 1140 mm, heat treatment was performed at 170 ° C. for 2 minutes in the first step, 230 ° C. for 2 minutes in the second step, and 350 ° C. for 10 minutes in the third step. It was removed to be within the range of values. Thereafter, it was cooled to room temperature for 2 minutes, and portions with poor flatness at both ends of the film were cut out with a slitter, and wound into a roll shape to obtain a polyimide film 4A shown in Table 1.

[Production Example 5 of Polyimide Film]

Polyamic acid solution A was coated on the surface with a surface roughness (Sa) of 1 nm, a maximum protrusion height (Sp) of 7 nm, a peak point density (Spd) of 20/square μm or less, and It was applied to a non-layered polyester film using a comma coater (coating width: 1240 mm), and dried at 90 to 115° C. for 10 minutes. After drying, the self-supporting polyamic acid film (containing 10% by mass of residual solvent) was peeled off from the support and both ends were cut to obtain a green film. The obtained green film was conveyed by a pin tenter so that the final pin sheet interval was 1140 mm, heat treatment was performed at 170 ° C. for 2 minutes in the first step, 230 ° C. for 2 minutes in the second step, and 350 ° C. for 10 minutes in the third step. It was removed to be within the range of values. Thereafter, it was cooled to room temperature for 2 minutes, and portions with poor flatness at both ends of the film were cut out with a slitter, and wound into a roll shape to obtain a polyimide film 5A shown in Table 1.

[Production Example 6 of Polyimide Film]

Polyimide solution C has a surface roughness (Sa) of 1 nm, a maximum protrusion height (Sp) of 7 nm, a peak point density (Spd) of 20/square μm or less, and a coating layer on the surface of the point, which is a film production support. It was applied using a comma coater to a polyester film without (coating width: 1240 mm), and dried at 90 to 115° C. for 10 minutes. After drying, the self-supporting polyamic acid film (containing 10% by mass of residual solvent) was peeled off from the support and both ends were cut to obtain a green film. The obtained green film was conveyed by a pin tenter so that the final pin sheet interval was 1140 mm, heat treatment was performed at 170 ° C. for 2 minutes in the first step, 230 ° C. for 2 minutes in the second step, and 350 ° C. for 1 minute in the third step. It was removed to be within the range of values. Thereafter, it was cooled to room temperature for 2 minutes, and portions with poor flatness at both ends of the film were cut out with a slitter and wound into a roll to obtain a polyimide film 6C shown in Table 1.

[Production Example 7 of Polyimide Film]

Polyimide solution B was applied to an unstretched polypropylene film having a surface roughness (Sa) of 3 nm, a maximum protrusion height (Sp) of 12 nm, and a peak point density (Spd) of 25/square μm or less at the points of the film production support. It was applied using a comma coater (coating width: 450 mm) and dried at 85 to 105° C. for 30 minutes to obtain a two-layer film of a support and a polyimide film (including about 8% by mass of residual solvent). Next, this two-layer film was stretched 2.8 times in the MD direction using the difference in circumferential speed of the rolls at the same time. Moreover, between the rolls with the circumferential speed difference, it arrange|positioned so that a roll might not contact the surface of the polyimide film side of a two-layer film. After stretching in the MD direction, both ends of the two-layer film are held by a clip tenter, and the final pin sheet interval is 1140 mm, that is, 2.5 times in the TD direction. The polyimide film was peeled from the support and further subjected to heat treatment at 350°C for 1 minute to remove residual solvent so as to be within a predetermined range. Thereafter, it was cooled to room temperature for 2 minutes, and portions with poor flatness at both ends of the film were cut out with a slitter and wound into a roll to obtain a polyimide film 7B shown in Table 1.

[Preparation of composition D for forming self-healing layer]

A composition for forming a polyurethane acrylate copolymer as a polymer composition having a crosslinking point formed by a chemical bond other than a covalent bond was weighed as follows, and mixed and prepared at room temperature.

AUP-787 (urethane acrylate containing photopolymerization initiator, manufactured by Tokushiki Co., Ltd.): 100 parts by mass

Methyl ethyl ketone: 50 parts by mass

Propylene glycol monomethyl ether: 30 parts by mass

BYK-381 (surfactant, manufactured by Big Chemie Japan): 1 part by mass

[Preparation of composition E for forming a self-healing layer]

A composition for forming a cyclodextrin ring penetrating polyether polymer as a polymer composition having a crosslinking point composed of constraints by geometric shapes not by chemical bonds was weighed as follows, and mixed and prepared at room temperature.

SM3405P (modified polyrotaxane, manufactured by Advanced Soft Material Co., Ltd.): 50 parts by mass

M-309 (trimethylolpropane triacrylate, manufactured by Toagosei): 35 parts by mass

M284 (polyethylene glycol diacrylate, manufactured by Toyo Chemicals): 15 parts by mass

Methyl ethyl ketone: 40 parts by mass

Propylene glycol monomethyl ether: 10 parts by mass

Omnirad184 (photopolymerization initiator, manufactured by IGMResins): 4 parts by mass

[Preparation of Composition F for Forming Hard Coat Layer]

A composition for forming a (meth)acrylate copolymer as a polymer composition for forming a hard coat layer was weighed as follows, and mixed and prepared at room temperature.

OPSTAR Z7530 (a mixture of organically modified silica fine particles and polyfunctional acrylate, manufactured by Arakawa Chemical Industry Co., Ltd.): 100 parts by mass

Pentaerythritol triacrylate: 34 parts by mass

1-hydroxycyclohexylphenyl ketone: 1.8 parts by mass

BYK-300 (leveling agent, manufactured by Big Chemie Japan): 0.1 part by mass

Propylene glycol monomethyl ether: 80 parts by mass

Example 1

<Manufacture of laminated body>

The self-healing layer-forming composition D was applied to the entire surface of the polyimide film 1A obtained in Production Example 1 by a roll coater. Subsequently, after drying at 80 ° C., while purging with nitrogen so that the oxygen concentration is 1.0% by volume or less, the irradiation area is 100 mW / square cm, and the irradiation amount is 0.3 J / square cm using an ultraviolet lamp. The layer was cured to create a laminate with a self-healing layer having a laminate thickness of 22.0 µm and a dry layer thickness of 9.5 µm.

Examples 2 to 13

In the same manner, a laminate was produced using the polyimide film and the self-healing layer-forming compositions D and E shown in Table 1, and the characteristics of the laminate were evaluated. The results are shown in Table 2.

Comparative Examples 1 to 8

Similarly, laminates were prepared using the polyimide films and the self-healing layer-forming compositions D, E, and F shown in Table 1, and the characteristics of the laminates were evaluated. The results are shown in Table 3.

As described above, the laminate of the present invention exhibits excellent transparency, self-healing properties, and flexibility, and has excellent adhesion to the self-healing layer, so that the image display portion can be folded. Very useful around the front plate and electrodes.

Claims (5)

A polyimide film having a tensile modulus of elasticity of 3 GPa or more in both MD and TD directions, a CTE of -5 ppm/°C to +55 ppm/°C in both MD and TD directions, and a solvent content of 0.5 to 5.0% by mass; , A laminate comprising a self-healing layer formed on at least one side of the polyimide film. According to claim 1,
After applying a minute load of 0.5 mN to the surface from a Vickers square pyramid diamond indenter with a micro hardness tester and holding it for 5 seconds, the return rate after removing the load to 0.005 mN and holding it for 60 seconds is 80% or more Laminate, characterized in that. According to claim 1 or 2,
A laminate characterized in that the adhesion rate of the self-healing layer cut in a lattice shape to the polyimide film by the crosscut method of JIS K 5600-5-6 (1999) is 80% or more. According to any one of claims 1 to 3,
A laminate characterized by having a yellow index of 10 or less, a light transmittance of 70% or more at a wavelength of 400 nm, and a total light transmittance of 85% or more. According to any one of claims 1 to 4,
A laminate characterized in that the self-healing layer is a polymer composition containing crosslinking points, and some or all of the crosslinking points are crosslinking points having mobility.