CN113950409B

CN113950409B - Laminate body

Info

Publication number: CN113950409B
Application number: CN202080043320.9A
Authority: CN
Inventors: 成泽春彦; 渡边直树; 涌井洋行; 米虫治美
Original assignee: Toyobo Co Ltd
Current assignee: Toyobo Co Ltd
Priority date: 2019-12-17
Filing date: 2020-12-01
Publication date: 2024-06-28
Anticipated expiration: 2040-12-01
Also published as: CN118578738A; JP7151904B2; JP7268791B2; JP2022180528A; JPWO2021124865A1; CN113950409A; WO2021124865A1

Abstract

The present invention provides a laminate which can stably peel a polyimide film from a protective film even after storage, and which does not cause deterioration in adhesion or plasticization or whitening of the polyimide film. The laminate obtained by the present invention achieves the object by using a protective film having a low molecular weight component of 0.03 to 3.0 mass% extracted with a solvent, and controlling the contact transfer amount of the solvent-extracted low molecular weight component in the protective film to 0.5 to 50mg/m ² after storage under load relative to the polyimide film surface.

Description

Laminate body

Technical Field

The present invention relates to a laminate composed of a protective film and a polyimide film.

Background

In recent years, for the purpose of weight reduction, miniaturization/thinning, and flexibility (flexibility) of functional elements such as semiconductor elements, MEMS elements, and display elements, development of techniques for forming these elements on polyimide films has been actively conducted. That is, as a material of a base material of an electronic component such as an information communication device (a broadcasting device, a wireless mobile device, a portable communication device, or the like), a radar, a high-speed information processing device, or the like, a ceramic having heat resistance and capable of coping with a high frequency of a signal band of the information communication device (reaching a GHz band) has been conventionally used, but the ceramic is inflexible and is difficult to thin, and therefore, there is a disadvantage that an applicable field is limited, and therefore, a polyimide film has been recently used as a substrate.

When such functional elements such as semiconductor elements, MEMS elements, and display elements are formed on the surface of a polyimide film, processing by a so-called roll-to-roll (roll-to-roll) process is expected to be performed by utilizing flexibility as a characteristic of the polyimide film. Polyimide films used in roll-to-roll processes can be produced continuously by coating a support substrate with a varnish containing a polymer such as polyimide dissolved in a solvent, peeling the film from the support substrate, and drying the film to remove the solvent.

When used in the roll-to-roll process, scratches, abrasion, wrinkles, and the like are generated on the surface of the polyimide film formed by film formation when the polyimide film is brought into contact with a metal guide roll or subjected to film loading treatment, and therefore a releasable protective film can be properly laminated thereon to protect the film surface (patent documents 1 to 3).

Prior art literature

Patent literature

Patent document 1: japanese patent laid-open No. 4-359585

Patent document 2: japanese patent laid-open No. 2007-169458

Patent document 3: japanese patent No. 6538259

Disclosure of Invention

Problems to be solved by the invention

In a polyimide film laminate in which a protective film is laminated to protect the surface of the film, when functional elements such as semiconductor elements, MEMS elements, and display elements are formed on the surface thereof, it is necessary to peel the protective film from the laminate of the protective film and the polyimide film in advance. In this case, when the protective film is continuously peeled, peeling may be uneven, and flaws, wrinkles, and the like may occur in the polyimide film, which may cause poor appearance, formability of functional elements, and processing defects.

In addition, the laminate of the protective film and the polyimide may be unstable in peeling off the protective film after the preservation of the polyimide film from the time of attachment of the protective film to the time of subsequent processing, and further, the polyimide film may be degraded in adhesiveness, plasticized, or whitened. Such a decrease in adhesiveness, plasticization, or whitening of a polyimide film is a defect in applications such as display elements.

The protective film contains a low molecular weight component, which is a monomer or oligomer derived from a raw material, in the film base material and the adhesive layer. The composition further contains, if necessary, low molecular weight components such as softeners, plasticizers, anti-aging agents, antioxidants, ultraviolet absorbers, light stabilizers, surface lubricants, leveling agents, mold release agents, flame retardants, corrosion inhibitors, heat stabilizers, polymerization inhibitors, slipping agents, solvents, and the like.

Such unevenness in peeling of the protective film, unstable peeling of the polyimide film after storage, reduced adhesiveness, and whitening are caused mainly by that these low molecular weight components in the protective film come into contact with the polyimide film and precipitate from the inside of the protective film to the contact surface, and gradually migrate to the polyimide film side, so that there is a problem in that the component amount of the extracted low molecular weight components in the protective film and the contact migration amount are controlled.

Means for solving the problems

The present inventors have made intensive studies to solve the above problems, and as a result, have completed the present invention. That is, the present invention has the following configurations [1] to [6 ].

[1] A laminate comprising a polyimide film and a protective film bonded to at least one surface of the polyimide film,

The polyimide film has a yellow index of 10 or less, a light transmittance of 70% or more at a wavelength of 400nm, a total light transmittance of 85% or more, CTE in both MD and TD directions of-5 ppm/. Degree.C to +55 ppm/. Degree.C,

The solvent-extracted low-molecular-weight component contained in the protective film peeled from the laminate is 0.03 to 3.0 mass%.

[2] The laminate according to [1], wherein the low molecular weight component is extracted from the solvent contained in the polyimide film peeled off from the laminate by 0.5 to 50mg/m ² after the laminate is stored at 40℃for 7 days under a load of 100g/cm ².

[3] The laminate according to [1] or [2], wherein an initial peel strength of the protective film at the time of peeling the protective film from the laminate by a 90-degree peeling method is 0.06N/cm or more and 0.25N/cm or less.

[4] The laminate according to any one of [1] to [3], wherein the peel strength of the protective film by a 90-degree peel method when the laminate is stored at 40℃for 7 days under a load of 100g/cm ² is 0.06N/cm or more and 0.25N/cm or less.

[5] The laminate according to any one of [1] to [4], wherein the polyimide film has a tensile elastic modulus in both the MD direction and the TD direction of 3GPa to 20 GPa.

[6] The laminate according to any one of [1] to [5], wherein the protective film is composed of a polycondensation resin film and a binder.

Here, the MD direction refers to the machine direction of the film, and the TD direction refers to the width direction of the film.

ADVANTAGEOUS EFFECTS OF INVENTION

By using the laminate of the present invention, the polyimide film is uniformly peeled off, and the polyimide film is less likely to be scratched or wrinkled, and the laminate can maintain low peel strength and uniformity even when stored for a long period of time, and the polyimide film is less likely to be whitened or reduced in adhesiveness. Therefore, a laminate having excellent appearance, functional element formability, and workability, and having a surface suitable for forming functional elements such as semiconductor elements, MEMS elements, and display elements, can be provided.

Detailed Description

Hereinafter, a laminate according to an embodiment of the present invention will be described. The laminate of the present invention is a laminate comprising a polyimide film and a protective film bonded to at least one surface of the polyimide film, and 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, a polyamideimide film, or a polyamide film, more preferably a polyimide film or a polyamideimide film, and still more preferably a polyimide film.

In general, a polyimide film can be obtained by: a polyamic acid (polyimide precursor) solution obtained by reacting diamines and tetracarboxylic acids in a solvent is applied to a support for producing a polyimide film, and dried to form a green film (also referred to as a "precursor film" or a "polyamic acid film" or "Polyamic acid film"), and the green film is further subjected to a dehydration cyclization reaction on the support for producing a polyimide film or in a state of being peeled from the support, thereby obtaining a polyimide film. As another method, the method may be obtained as follows: the polyimide film is produced by applying a polyimide solution obtained by a dehydration cyclization reaction of diamines and tetracarboxylic acids in a solvent to a support for producing a polyimide film, drying the polyimide film to form a polyimide film containing 1 to 50 mass% of the solvent, and further subjecting the polyimide film containing 1 to 50 mass% of the solvent to a high-temperature treatment on the support for producing a polyimide film or in a state of being peeled from the support, and drying the polyimide film.

In addition, in general, a polyamideimide film can be obtained by: the method comprises the steps of coating a polyamideimide solution obtained by reacting diisocyanates with tricarboxylic acids on a support for preparing a polyamideimide film, drying the same to form a polyamideimide film containing 1 to 50 mass% of a solvent, and further carrying out high-temperature treatment on the polyamideimide film containing 1 to 50 mass% of the solvent on the support for preparing the polyamideimide film or in a state of being separated from the support, and drying the same.

In addition, in general, the polyamide film can be obtained by: the polyamide film is produced by applying a polyamide solution obtained by reacting a diamine with a dicarboxylic acid to a support for producing a polyamide film, drying the polyamide solution to form a polyamide film containing 1 to 50 mass% of a solvent, and further subjecting the polyamide film containing 1 to 50 mass% of the solvent to a high-temperature treatment on the support for producing a polyamide film or in a state of being peeled from the support, and drying the polyamide film.

As the tetracarboxylic acids, tricarboxylic acids, and dicarboxylic acids, aromatic tetracarboxylic acids (including anhydrides thereof), aliphatic tetracarboxylic acids (including anhydrides thereof), alicyclic tetracarboxylic acids (including anhydrides thereof), aromatic tricarboxylic acids (including anhydrides thereof), aliphatic tricarboxylic acids (including anhydrides thereof), alicyclic tricarboxylic acids (including anhydrides thereof), aromatic dicarboxylic acids, aliphatic dicarboxylic acids, and alicyclic dicarboxylic acids, which are generally used in polyimide synthesis, polyamideimide synthesis, and polyamide synthesis, can be used. Among them, aromatic tetracarboxylic acid anhydrides and alicyclic tetracarboxylic acid anhydrides are preferable, aromatic tetracarboxylic acid anhydrides are more preferable from the viewpoint of heat resistance, and alicyclic tetracarboxylic acids are more preferable from the viewpoint of light transmittance. When the tetracarboxylic acid is an acid anhydride, the molecule may have 1 or 2 acid anhydride structures, but a substance having 2 acid anhydride structures (dianhydride) is preferable. The tetracarboxylic acid, tricarboxylic acid, and dicarboxylic acid may be used singly or in combination.

Examples of the aromatic tetracarboxylic acids used for obtaining the polyimide of high colorless transparency of the present invention include 4,4'- (2, 2-hexafluoroisopropylidene) diphthalic acid, 4' -oxydiphthalic acid, bis (1, 3-dioxo-1, 3-dihydro-2-benzofuran-5-carboxylic acid) 1, 4-phenylene ester, bis (1, 3-dioxo-1, 3-dihydro-2-benzofuran-5-yl) benzene-1, 4-dicarboxylic acid ester, 4'- [4,4' - (3-oxo-1, 3-dihydro-2-benzofuran-1, 1-diyl) bis (benzene-1, 4-dioxy) ] diphenyl-1, 2-dicarboxylic acid, 3,3', 4' -benzophenone tetracarboxylic acid, 4'- [ (3-oxo-1, 3-dihydro-2-benzofuran-1, 1-diyl) bis (toluene-2, 5-diyloxy) ] diphenyl-1, 2-dicarboxylic acid, 4' - [ (3-oxo-1, 3-dihydro-2-benzofuran-1, 1-diyl) bis (1, 4-xylene-2, 5-diyloxy) ] diphenyl-1, 2-dicarboxylic acid, 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-diyloxy) ] diphenyl-1, 2-dicarboxylic acid, 4'- [4,4' - (3H-2, 1-benzoxathiene-bicyclo (benzoxathiole) -1, 1-dioxide-3, 3-diyl) bis (benzene-1, 4-diyloxy) ] diphenyl-1, 2-dicarboxylic acid, 4 '-benzophenone tetracarboxylic acid, 4' - [ (3H-2, 1-benzoxathiene-1, 1-dioxide-3, 3-diyl) bis (toluene-2, 5-diyloxy) ] diphenyl-1, 2-dicarboxylic acid, 4,4' - [ (3H-2, 1-Benzoxothiolane-1, 1-dioxide-3, 3-diyl) ] bis (1, 4-xylene-2, 5-diyloxy) ] diphenyl-1, 2-dicarboxylic acid, 4' - [4,4' - (3H-2, 1-Benzoxothiolane-1, 1-dioxide-3, 3-diyl) ] bis (4-isopropyl-toluene-2, 5-diyloxy) ] diphenyl-1, 2-dicarboxylic acid, 4' - [4,4' - (3H-2, 1-benzoxathiane-1, 1-dioxide-3, 3-diyl) ] bis (naphthalene-1, 4-diyloxy) ] diphenyl-1, 2-dicarboxylic acid, 3,3',4' -benzophenone tetracarboxylic acid, 3',4,4' -diphenyl sulfone tetracarboxylic acid, 3',4' -biphenyl tetracarboxylic acid, 2, 3', tetracarboxylic acids such as 4' -biphenyltetracarboxylic acid, pyromellitic acid, 4'- [ spiro (xanthene-9, 9' -fluorene) -2, 6-diylbis (oxycarbonyl) ] diphenyl-1, 2-dicarboxylic acid, and 4,4'- [ spiro (xanthene-9, 9' -fluorene) -3, 6-diylbis (oxycarbonyl) ] diphenyl-1, 2-dicarboxylic acid, and anhydrides thereof. Of these, dianhydride having 2 acid anhydride structures is preferable, and 4,4'- (2, 2-hexafluoroisopropylidene) diphthalic dianhydride and 4,4' -oxydiphthalic dianhydride are particularly preferable. The aromatic tetracarboxylic acids may be used alone or in combination of two or more. In the case of considering heat resistance, the aromatic tetracarboxylic acids are preferably 50 mass% or more, more preferably 60 mass% or more, still more preferably 70 mass% or more, and still more preferably 80 mass% or more of the total tetracarboxylic acids, for example.

Examples of the alicyclic tetracarboxylic acids include 1,2,3, 4-cyclobutanetetracarboxylic acid, 1,2,3, 4-cyclopentanetetracarboxylic acid, 3- (carboxymethyl) cyclopentane-1, 2, 4-tricarboxylic acid, 1,2,3, 4-cyclohexaneditetracarboxylic acid, 1,2,4, 5-cyclohexanedicarboxylic acid, 3', 4' -dicyclohexyltetracarboxylic acid, bicyclo [2, 1] heptane-2, 3,5, 6-tetracarboxylic acid, bicyclo [2, 2] octane-2, 3,5, 6-tetracarboxylic acid, bicyclo [2, 2] oct-7-ene-2, 3,5, 6-tetracarboxylic acid, tetradecanoine-2, 3,6, 7-tetracarboxylic acid, Decatetrahydro-1, 4:5,8:9, 10-trimethyl anthracene-2, 3,6, 7-tetracarboxylic acid, decahydronaphthalene-2, 3,6, 7-tetracarboxylic acid, decahydro-1, 4:5, 8-Di-alpha-naphthalene-2, 3,6, 7-tetracarboxylic acid, decahydro-1, 4-ethylidene-5, 8-alpha-naphthalene-2, 3,6, 7-tetracarboxylic acid, norbornane-2-spiro-alpha-cyclopentanone-alpha '-spiro-2' -norbornane-5, 5', 6,6 "-tetracarboxylic acid (also known as" norbornane-2-spiro-2' -cyclopentanone-5 '-spiro-2 "-norbornane-5, 5",6 "-tetracarboxylic acid"), methylnorbornane-2-spiro-alpha-cyclopentanone-alpha' -spiro-2 "- (methylnorbornane) -5,5",6 "-tetracarboxylic acid, norbornane-2-spiro-alpha-cyclohexanone-alpha ' -spiro-2 "-norbornane-5, 5",6 "-tetracarboxylic acid (also known as" norbornane-2-spiro-2 ' -cyclohexanone-6 ' -spiro-2 "-norbornane-5, 5",6, 6' -tetracarboxylic acid "), methyl norbornane-2-spiro-alpha-cyclohexanone-alpha ' -spiro-2 ' - (methyl norbornane) -5,5 ', 6,6" -Tetracarboxylic acid, norbornane-2-spiro-alpha-cyclo-propanone-alpha ' -spiro-2 "-norbornane-5, 5",6 "-Tetracarboxylic acid, norbornane-2-spiro-alpha-cyclo-butanone-alpha ' -spiro-2" -norbornane-5, 5", 6" -Tetracarboxylic acid, Norbornane-2-spiro-alpha-cycloheptanone-alpha ' -spiro-2 "-norbornane-5, 5",6,6 ' -tetracarboxylic acid, norbornane-2-spiro-alpha-cyclooctanone-alpha ' -spiro-2 ' -norbornane-5, 5 ', 6,6 ' -tetracarboxylic acid, norbornane-2-spiro-alpha-cyclononone-alpha ' -spiro-2 ' -norbornane-5, 5 ', 6,6 "-Tetracarboxylic acid, norbornane-2-spiro-alpha-cyclodecyl-alpha ' -spiro-2" -norbornane-5, 5", 6" -Tetracarboxylic acid, norbornane-2-spiro-alpha-cycloundecanone-alpha ' -spiro-2 "-norbornane-5, 5",6 "-Tetracarboxylic acid, norbornane-2-spiro-alpha-cyclododecanone-alpha '-spiro-2 "-norbornane-5, 5",6 "-tetracarboxylic acid, norbornane-2-spiro-alpha-cyclotridecanone-alpha' -spiro-2" -norbornane-5, 5",6,6 '-tetracarboxylic acid, norbornane-2-spiro-alpha-cyclotetradecanone-alpha' -spiro-2 '-norbornane-5, 5', 6,6" -Tetracarboxylic acid, norbornane-2-spiro-alpha-cyclopentadecanone-alpha '-spiro-2 "-norbornane-5, 5",6 "-Tetracarboxylic acid, norbornane-2-spiro-alpha- (methylcyclopentanone) -alpha' -spiro-2" -norbornane-5, 5", 6" -Tetracarboxylic acid, Norbornane-2-spiro-alpha- (methylcyclohexanone) -alpha' -spiro-2 "-norbornane-5, 5",6 "-tetracarboxylic acid and their anhydrides. Of these, dianhydride having 2 acid anhydride structures is preferable, and in particular, 1,2,3, 4-cyclobutane tetracarboxylic acid dianhydride, 1,2,3, 4-cyclohexane tetracarboxylic acid dianhydride, 1,2,4, 5-cyclohexane tetracarboxylic acid dianhydride, more preferably 1,2,3, 4-cyclobutane tetracarboxylic acid dianhydride, 1,2,4, 5-cyclohexane tetracarboxylic acid dianhydride, and still more preferably 1,2,3, 4-cyclobutane tetracarboxylic acid dianhydride is preferable. These may be used alone or in combination of two or more. In the case of considering transparency, the alicyclic tetracarboxylic acids are preferably 50 mass% or more, more preferably 60 mass% or more, still more preferably 70 mass% or more, and still more preferably 80 mass% or more of the total tetracarboxylic acids, for example.

Examples of the tricarboxylic acids include trimellitic acid, aromatic tricarboxylic acids such as 1,2, 5-naphthalene tricarboxylic acid, diphenyl ether-3, 3',4' -tricarboxylic acid, and diphenyl sulfone-3, 3',4' -tricarboxylic acid, and hydrogenated products of the above aromatic tricarboxylic acids such as hexahydrotrimellitic acid, ethylene glycol bis-trimellitate, propylene glycol bis-trimellitate, 1, 4-butanediol bis-trimellitate, and alkylene glycol bis-trimellitate such as polyethylene glycol bis-trimellitate, and monoanhydrides and esters thereof. Of these, monoanhydrides having 1 acid anhydride structure are preferable, and in particular, trimellitic anhydride and hexahydrotrimellitic anhydride are preferable. These may be used alone or in combination of two or more.

Examples of the dicarboxylic acid include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid, naphthalene dicarboxylic acid, biphenyl-4, 4 '-dicarboxylic acid, and 4,4' -oxybenzoic acid, and hydrogenated products of the above aromatic dicarboxylic acids such as 1, 6-cyclohexanedicarboxylic acid, oxalic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, 2-methylsuccinic acid, and acid chlorides or esters thereof. Among these, aromatic dicarboxylic acids and their hydrides are preferable, and in particular, terephthalic acid, 1, 6-cyclohexanedicarboxylic acid, and 4,4' -oxydiphenylcarboxylic acid are preferable. The dicarboxylic acids may be used alone or in combination of two or more.

The diamine or isocyanate used to obtain the polyimide of high colorless transparency in the present invention is not particularly limited, and aromatic diamines, aliphatic diamines, alicyclic diamines, aromatic diisocyanates, aliphatic diisocyanates, alicyclic diisocyanates, etc. which are generally used for polyimide synthesis, polyamideimide synthesis, polyamide synthesis can be used. Aromatic diamines are preferred from the viewpoint of heat resistance, and alicyclic diamines are preferred from the viewpoint of transparency. In addition, when aromatic diamines having a benzoxazole structure are used, high heat resistance, high elastic modulus, low heat shrinkage, and low linear expansion coefficient can be achieved. The diamines and isocyanates may be used singly 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 '-bistrifluoromethyl-4, 4' -diaminobiphenyl, 4 '-bis (4-aminophenoxy) biphenyl, 4' -bis (3-aminophenoxy) biphenyl, bis [4- (3-aminophenoxy) phenyl ] ketone, bis [4- (3-aminophenoxy) phenyl ] sulfide, bis [4- (3-aminophenoxy) phenyl ] sulfone, 2-bis [4- (3-aminophenoxy) phenyl ] propane, 2, 2-bis [4- (3-aminophenoxy) phenyl ] -1, 3-hexafluoropropane, m-phenylenediamine, o-phenylenediamine, p-phenylenediamine, m-aminobenzylamine, p-aminobenzylamine, 4-amino-N- (4-aminophenyl) benzamide, 3' -diaminodiphenyl ether 3,4' -diaminodiphenyl ether, 4' -diaminodiphenyl ether, 2' -trifluoromethyl-4, 4' -diaminodiphenyl ether, 3' -diaminodiphenyl sulfide, 3' -diaminodiphenyl sulfoxide, 3,4' -diaminodiphenyl sulfoxide, 4' -diaminodiphenyl sulfoxide, 3,3' -diaminodiphenyl sulfone, 3,4' -diaminodiphenyl sulfone, 4' -diaminodiphenyl sulfone, 3' -diaminobenzophenone, 3,4' -diaminobenzophenone, 4' -diaminobenzophenone, 3' -diaminodiphenyl methane, 3,4' -diaminodiphenyl methane 4,4' -diaminodiphenylmethane, bis [4- (4-aminophenoxy) phenyl ] methane, 1-bis [4- (4-aminophenoxy) phenyl ] ethane, 1, 2-bis [4- (4-aminophenoxy) phenyl ] ethane, 1-bis [4- (4-aminophenoxy) phenyl ] propane, 1, 2-bis [4- (4-aminophenoxy) phenyl ] propane, 1, 3-bis [4- (4-aminophenoxy) phenyl ] propane, 2-bis [4- (4-aminophenoxy) phenyl ] propane, 1-bis [4- (4-aminophenoxy) phenyl ] butane, 1, 3-bis [4- (4-aminophenoxy) phenyl ] butane, 1, 4-bis [4- (4-aminophenoxy) phenyl ] butane, 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-bis [4- (4-aminophenoxy) -3, 5-dimethylphenyl ] propane 2, 2-bis [4- (4-aminophenoxy) phenyl ] -1, 3-hexafluoropropane, 1, 4-bis (3-aminophenoxy) benzene, 1, 3-bis (3-aminophenoxy) benzene, 1, 4-bis (4-aminophenoxy) benzene, 4' -bis (4-aminophenoxy) biphenyl, Bis [4- (4-aminophenoxy) phenyl ] ketone, bis [4- (4-aminophenoxy) phenyl ] sulfide, bis [4- (4-aminophenoxy) phenyl ] sulfoxide, bis [4- (4-aminophenoxy) phenyl ] sulfone, bis [4- (3-aminophenoxy) phenyl ] ether, bis [4- (4-aminophenoxy) phenyl ] ether, 1, 3-bis [4- (4-aminophenoxy) benzoyl ] benzene, 1, 3-bis [4- (3-aminophenoxy) benzoyl ] benzene, 1, 4-bis [4- (3-aminophenoxy) benzoyl ] benzene, 4' -bis [ (3-aminophenoxy) benzoyl ] benzene, 1, 1-bis [4- (3-aminophenoxy) phenyl ] propane, 1, 3-bis [4- (3-aminophenoxy) phenyl ] propane, 3,4 '-diaminodiphenyl sulfide, 2-bis [3- (3-aminophenoxy) phenyl ] -1, 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' -bis [3- (4-aminophenoxy) benzoyl ] diphenyl ether, 4,4' -bis [3- (3-aminophenoxy) benzoyl ] diphenyl ether, 4' -bis [4- (4-amino- α, α -dimethylbenzyl) phenoxy ] benzophenone, 4' -bis [4- (4-amino- α, α -dimethylbenzyl) phenoxy ] diphenyl sulfone, bis [4- {4- (4-aminophenoxy) phenoxy } phenyl ] sulfone, 1, 4-bis [4- (4-aminophenoxy) phenoxy- α, α -dimethylbenzyl ] benzene, 1, 3-bis [4- (4-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 '-diamino-4, 4' -diphenoxybenzophenone, 4 '-diamino-5, 5' -diphenoxybenzophenone, 3,4 '-diamino-4, 5' -diphenoxybenzophenone, 3 '-diamino-4-phenoxybenzophenone, 4' -diamino-5-phenoxybenzophenone, 3,4 '-diamino-4-phenoxybenzophenone, 3,4' -diamino-5 '-phenoxybenzophenone, 3' -diamino-4, 4 '-diphenoxybenzophenone, 4' -diamino-5, 5 '-diphenoxybenzophenone, 3,4' -diamino-4, 5 '-diphenoxybenzophenone, 3' -diamino-4-diphenoxybenzophenone, 4 '-diamino-5-diphenoxybenzophenone, 3,4' -diamino-4-diphenoxybenzophenone, 3,4 '-diamino-5' -diphenoxybenzophenone, 1, 3-bis (3-amino-4-phenoxybenzoyl) benzene, 1, 4-bis (3-amino-4-phenoxybenzoyl) benzene, 1, 3-bis (4-amino-5-phenoxybenzoyl) benzene, 1, 4-bis (4-amino-5-phenoxybenzoyl) benzene, 1, 3-bis (3-amino-4-diphenoxybenzoyl) benzene, 1, 4-bis (3-amino-4-diphenoxybenzoyl) benzene, 1, 3-bis (4-amino-5-diphenoxybenzoyl) benzene, 1, 4-bis (4-amino-5-diphenoxybenzoyl) benzene, 2, 6-bis [4- (4-amino-alpha, alpha-dimethylbenzyl) phenoxy ] benzonitrile, 4'- [ spiro (xanthene-9, 9' -fluorene) -2, 6-diylbis (oxycarbonyl) ] diphenylamine, 4,4'- [ spiro (xanthene-9, 9' -fluorene) -3, 6-diylbis (oxycarbonyl) ] diphenylamine, an aromatic diamine in which part or all of hydrogen atoms on an aromatic ring of the aromatic diamine are substituted with a halogen atom, an alkyl group or an alkoxy group having 1 to 3 carbon atoms, a cyano group, or a haloalkyl group or an alkoxy group having 1 to 3 carbon atoms in which part or all of hydrogen atoms of the alkyl group or the alkoxy group are substituted with a halogen atom, and the like. In addition, 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 '-p-phenylenebis (5-aminobenzoxazole), 2' -p-phenylenebis (6-aminobenzoxazole), 1- (5-amino) benzoxazole) -4- (6-aminobenzoxazole) benzene, 2,6- (4, 4 '-diaminodiphenyl) benzo [1,2-d:5,4-d' ] bisoxazoles, 2,6- (4, 4' -diaminodiphenyl) benzo [1,2-d:4,5-d ' ] bisoxazole, 2,6- (3, 4' -diaminodiphenyl) benzo [1,2-d:5,4-d ' ] bisoxazole, 2,6- (3, 4' -diaminodiphenyl) benzo [1,2-d:4,5-d ' ] bisoxazole, 2,6- (3, 3' -diaminodiphenyl) benzo [1,2-d:5,4-d ' ] bisoxazole, 2,6- (3, 3' -diaminodiphenyl) benzo [1,2-d:4,5-d ' ] bisoxazole, and the like. Among these, 2 '-bistrifluoromethyl-4, 4' -diaminobiphenyl, 4-amino-N- (4-aminophenyl) benzamide, 4 '-diaminodiphenyl sulfone, 3' -diaminobenzophenone are particularly preferable. The aromatic diamines may be used alone or in combination of two or more.

Examples of the alicyclic diamines include 1, 4-diaminocyclohexane, 1, 4-diamino-2-methylcyclohexane, 1, 4-diamino-2-ethylcyclohexane, 1, 4-diamino-2-n-propylcyclohexane, 1, 4-diamino-2-isopropylcyclohexane, 1, 4-diamino-2-n-butylcyclohexane, 1, 4-diamino-2-isobutylcyclohexane, 1, 4-diamino-2-sec-butylcyclohexane, 1, 4-diamino-2-tert-butylcyclohexane, 4' -methylenebis (2, 6-dimethylcyclohexylamine), cyclohexane-1, 4-diyldimethylamine, and bicyclo [2, 1] heptane-2, 5-diamine. Among these, 1, 4-diaminocyclohexane and 1, 4-diamino-2-methylcyclohexane are particularly preferable, and 1, 4-diaminocyclohexane is more preferable. The alicyclic diamines may be used alone or in combination of two or more kinds.

As the diisocyanate compound, there is used, examples 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, diphenyl ketone-4, 4' -diisocyanate, diphenyl sulfone-4, 4' -diisocyanate, toluene-2, 4-diisocyanate, toluene-2, 6-diisocyanate, m-xylene diisocyanate, p-xylene diisocyanate, naphthalene-2, 6-diisocyanate, 4' - (2, 2) bis (4-phenoxyphenyl) propane) diisocyanate, 3' -or 2,2' -dimethylbiphenyl-4, 4' -diisocyanate, 3' -or 2,2' -diethylbiphenyl-4, 4' -diisocyanate, aromatic diisocyanates such as 3,3' -dimethoxybiphenyl-4, 4' -diisocyanate and 3,3' -diethoxybiphenyl-4, 4' -diisocyanate, and diisocyanates obtained by hydrogenating any of these (for example, isophorone diisocyanate, 1, 4-cyclohexane diisocyanate, 1, 3-cyclohexane diisocyanate, 4' -dicyclohexylmethane diisocyanate, and hexamethylene diisocyanate) and the like. Among these, diphenylmethane-4, 4 '-diisocyanate, toluene-2, 4-diisocyanate, toluene-2, 6-diisocyanate, 3' -dimethylbiphenyl-4, 4 '-diisocyanate or naphthalene-2, 6-diisocyanate, 4' -dicyclohexylmethane diisocyanate, 1, 4-cyclohexane diisocyanate are preferable from the viewpoints of low hygroscopicity, dimensional stability, price and polymerizability. In addition, the diisocyanate may be used alone or in combination of two or more.

The polyimide film of the present invention has a yellowness index (yellow index) of 10 or less, more preferably 7 or less, still more preferably 5 or less, and still more preferably 3 or less. The lower limit of the yellowness index of the polyimide film is not particularly limited, but is preferably 0.1 or more, more preferably 0.2 or more, and further preferably 0.3 or more for use as a flexible electronic device.

The polyimide film of the present invention has a light transmittance of 70% or more, more preferably 72% or more, still more preferably 75% or more, and still more preferably 80% or more at a wavelength of 400 nm. The upper limit of the light transmittance of the polyimide film at a wavelength of 400nm is not particularly limited, but is preferably 99% or less, more preferably 98% or less, and further preferably 97% or less for use as a flexible electronic device.

The polyimide film of the present invention has a total light transmittance of 85% or more, more preferably 86% or more, still more preferably 87% or more, and still more preferably 88% or more. The upper limit of the total light transmittance of the polyimide film is not particularly limited, but is preferably 99% or less, more preferably 98% or less, and further preferably 97% or less for use as a flexible electronic device.

The polyimide film of the present invention preferably has an average CTE of from 30℃to 300℃of-5 ppm/℃to +55ppm/℃and more preferably from-5 ppm/℃to +45ppm/℃and still more preferably from-5 ppm/℃to +35ppm/℃and still more preferably from-5 ppm/℃to +20ppm/℃and still more preferably from-1 ppm/℃to +10ppm/℃in terms of the average CTE. When the CTE is within the above range, the difference between the linear expansion coefficients of the polyimide film and the normal support (inorganic substrate) can be kept small, and peeling of the polyimide film and the inorganic substrate can be avoided even when the polyimide film is subjected to a heating step. Here, CTE is a coefficient (factor) indicating reversible expansion and contraction with respect to temperature. The CTE of the polyimide film is an average value of the CTE in the machine direction (MD direction) and the CTE in the width direction (TD direction) of the polyimide film. The method for measuring CTE of the polyimide film was as described in examples.

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, and still more preferably 45 μm or more. The upper limit of the thickness of the polyimide film is not particularly limited, but is preferably 250 μm or less, more preferably 150 μm or less, and further preferably 90 μm or less for use as a flexible electronic device.

The polyimide film exhibiting the colorless transparency having the linear expansion coefficient of the present invention can be obtained by stretching during the film formation of the polyimide film. The stretching operation may be accomplished as follows: the polyimide film is obtained by applying a polyimide solution to a support for producing a polyimide film and drying the applied polyimide solution to form a polyimide film containing 1 to 50 mass% of a solvent, and stretching the polyimide film containing 1 to 50 mass% of the solvent in the MD direction by 1.5 to 4.0 times and in the TD direction by 1.4 to 3.0 times in the process of drying the polyimide film on the support for producing a polyimide film or in a state of being peeled off from the support by a high-temperature treatment. In this case, by using an unstretched thermoplastic polymer film as a support for producing a polyimide film, stretching the thermoplastic polymer film and the polyimide film at the same time, and then peeling the stretched polyimide film from the thermoplastic polymer film, it is possible to prevent the occurrence of scratches on the polyimide film, particularly in the MD direction, and to obtain a polyimide film of higher quality and high colorless transparency.

The laminate of the present invention comprises a protective film bonded to the polyimide film. The protective film may be attached to only one side surface of the polyimide film, or may be attached to both sides. The protective film to be attached to the polyimide film is usually a film for temporarily protecting the surface of the polyimide film, and is not particularly limited as long as it is a releasable film capable of protecting the surface of the polyimide film, and is preferably selected from the group consisting of polycondensation resin films such as polyester, polylactic acid, polyamide, and the like, in terms of film strength and dimensional stability. In addition, from the viewpoint of low hygroscopicity, it is more preferably selected from the group consisting of polyester resin films. In the case where the protective films are laminated on both surfaces of the polyimide film, the protective films on the respective surfaces may be the same or different from each other.

The protective film of the present invention may have an adhesive layer on the surface to be bonded to the polyimide film, and the adhesive constituting the adhesive layer is not limited as long as it has adhesion and releasability, and examples of the type of the adhesive include acrylic adhesives, rubber adhesives (natural rubber adhesives or synthetic rubber adhesives), silicone adhesives, polyester adhesives, polyurethane adhesives, polyamide adhesives, epoxy adhesives, vinyl alkyl ether adhesives, and fluorine adhesives. 2 or more binders may be used in combination, and for example, a tackifier, a plasticizer, a filler, and a colorant may be added to the binder. Among them, the silicone-based adhesive and the acrylic-based adhesive are preferable in terms of the amount of the low molecular weight component extracted with the solvent and the contact transfer amount.

The pressure-sensitive adhesive layer may be formed by, for example, applying a pressure-sensitive adhesive to a film substrate and subjecting the film substrate to a crosslinking reaction by heating or irradiation with ultraviolet rays. For example, the pressure-sensitive adhesive may be applied to a release paper or other film, and the film may be crosslinked by heating or ultraviolet irradiation to form a pressure-sensitive adhesive layer, which is then bonded to one or both surfaces of the film substrate. As the application of the adhesive, for example, a roll coater, a die coater (die coater), a lip coater (lip coater), or the like may be used. In the case of heating after coating, the solvent in the adhesive composition may be removed simultaneously with the crosslinking reaction by heating.

The thickness of the protective film in the present invention is preferably 10 μm or more, more preferably 20m or more, from the viewpoints of protective performance and dimensional stability. The upper limit of the thickness of the protective film is not particularly limited, but is preferably 200 μm or less, more preferably 150 μm or less, in view of the ease of storage in the case of winding the laminate into a roll for storage.

The low molecular weight component contained in the laminate of the present invention can be extracted by performing a soxhlet extraction operation described later on the laminate of the present invention, or the protective film, the polyimide film, the protective film peeled from the laminate, or the polyimide film peeled from the laminate. In the present invention, the component extracted by such an operation is referred to as a solvent-extracted low molecular weight component.

The protective film of the present invention contains a low molecular weight component, which is a monomer or oligomer derived from a raw material, in the film base layer and the adhesive layer. In addition, the composition further comprises low molecular weight components such as softeners, plasticizers, anti-aging agents, antioxidants, ultraviolet absorbers, light stabilizers, surface lubricants, leveling agents, mold release agents, flame retardants, corrosion inhibitors, heat stabilizers, polymerization inhibitors, slipping agents, solvents and the like, which are added according to needs. The solvent-extracted low molecular weight component is mainly a component eluted by the soxhlet extraction operation from among such low molecular weight components.

In the present invention, the solvent-extracted low-molecular-weight component contained in the protective film after being peeled from the laminate is 0.03 to 3.0 mass%. Further, the solvent-extracted low-molecular-weight component contained in the protective film after being peeled from the laminate of the present invention is preferably in the range of 0.06 to 1.5% by mass, more preferably in the range of 0.1 to 0.8% by mass.

When the solvent-extracted low-molecular-weight component is within this range, excessive transfer of the solvent-extracted low-molecular-weight component from the protective film to the polyimide film can be suppressed, the peel strength does not significantly change even after long-term and high-temperature storage, the peel strength at the easy-peel level can be uniformly maintained, problems in physical properties such as whitening of the polyimide film and lowering of the glass transition temperature do not occur, and adhesion of the polyimide film to other raw materials in subsequent steps is not hindered, and a good state can be maintained.

In the present invention, the solvent-extracted low-molecular-weight component contained in the polyimide film peeled from the laminate is preferably 0.5 to 50mg/m ² after the laminate is stored at 40℃for 7 days under a load of 100g/cm ². The solvent-extracted low-molecular-weight component is more preferably 0.7 to 20mg/m ², still more preferably 1.0 to 10mg/m ².

In the present invention, the solvent extraction of the low molecular weight component contained in the polyimide film peeled from the laminate after the laminate is stored at 40℃for 7 days under a load of 100g/cm ² is also referred to as a contact transfer amount.

The solvent-extracted low molecular weight component in the protective film is brought into contact with the polyimide film through the protective film, and transferred to the surface of the polyimide film according to the elapsed time. The transfer of the solvent-extracted low molecular weight component causes problems in physical properties such as whitening of the polyimide film and lowering of the glass transition temperature, and in the subsequent step, problems such as blocking of adhesion when adhesion to other raw materials is required. Such a problem can be solved by controlling the contact transfer amount within a predetermined range.

The laminate of the present invention preferably has an initial peel strength of 0.06N/cm or more and 0.25N/cm or less at 90 degrees with respect to the protective film when the protective film is peeled from the laminate. By keeping the initial peel strength at 90 degrees within this range, unintentional peeling of the protective film during storage or in the functional element forming step can be prevented, peeling difficulties and peeling unevenness due to excessively high peel strength can be suppressed, and appearance defects such as scratches and wrinkles on the polyimide film side, functional element formability, processing defects, and the like can be prevented in advance.

In the laminate of the present invention, the peel strength by the 90 degree peel method when the protective film is peeled from the laminate after the laminate is stored at 40℃for 7 days under a load of 100g/cm ² is preferably 0.06N/cm or more and 0.25N/cm or less. By keeping the initial peel strength at 90 degrees within this range, unintentional peeling of the protective film during storage or in the functional element forming step can be prevented, peeling difficulties and peeling unevenness due to excessively high peel strength can be suppressed, and appearance defects such as scratches and wrinkles on the polyimide film side, functional element formability, processing defects, and the like can be prevented in advance.

The 90-degree peel strength was measured by the method described in examples.

The polyimide film of the present invention preferably has a tensile elastic modulus of 3GPa or more, more preferably 4GPa or more, and still more preferably 5GPa or more. When the tensile elastic modulus is 3GPa or more, the polyimide film is less in tensile deformation at the time of peeling from the protective film, and is excellent in handleability. The tensile elastic modulus is preferably 20GPa or less, more preferably 12GPa or less, and even more preferably 10GPa or less. When the tensile elastic modulus is 20GPa or less, the polyimide film can be used as a flexible film. The tensile elastic modulus of the polyimide film is an average value of the tensile elastic modulus in the machine direction (MD direction) and the tensile elastic modulus in the width direction (TD direction) of the polyimide film. The method for measuring the tensile modulus of the polyimide film was the method described in examples.

Examples

The present invention will be described in detail with reference to examples, but the present invention is not limited to the following examples as long as the gist of the present invention is not exceeded.

In addition, each measured value in examples and comparative examples was measured by the following method unless otherwise specified.

Reduced viscosity of Polymer

A solution of a polymer dissolved in N-methyl-2-pyrrolidone (or N, N-dimethylacetamide) at a concentration of 0.2g/dl was measured at 30℃by means of an Ubbelohde type viscosity tube. (in the case where N, N-dimethylacetamide is used as the solvent for producing the polyamic acid solution, measurement is performed by dissolving the polymer with N, N-dimethylacetamide.)

< Thickness of polyimide film >

The measurement was performed using a micrometer (Milltron 1245D, manufactured by Feinpruf GmbH).

< Yellowness index (yellowness index, YI) >

The tristimulus values XYZ values of the polyimide film were measured by using a colorimeter (ZE 6000, manufactured by japan electric color corporation) and a C2 light source according to ASTM D1925, and the Yellowness Index (YI) was calculated by the following formula. The same measurement was performed 3 times, and the arithmetic average value was used.

YI＝100×(1.28X-1.06Z)/Y

Light transmittance of < 400nm >)

The polyimide film peeled from the laminate was measured for light transmittance at a wavelength of 400nm using a spectrophotometer (U-2001 manufactured by Hitachi-Ltd.), and the obtained value was converted into a thickness of 20 μm according to the Lambert-beer law, and the obtained value was taken as the 400nm light transmittance of the polyimide film. The same measurement was performed 3 times, and the arithmetic average value was used.

< Total light transmittance (TT) >)

For the polyimide film peeled from the laminate, HAZEMETER (NDH 5000, manufactured by japan electrochromic corporation) was used to measure the total light transmittance (TT) of the polyimide film. As the light source, a D65 lamp was used. The same measurement was performed 3 times, and the arithmetic average value was used.

Coefficient of linear expansion (CTE) >

For the polyimide film peeled from the laminate, the elongation and elongation were measured in the machine direction (MD direction) and the width direction (TD direction) of the polyimide film under the following conditions, the elongation and elongation/temperature at 15 ℃ intervals were measured at 30 to 45 ℃ and 45 to 60 ℃, and the average value of the total measured values was calculated as CTE until the measurement was performed to 300 ℃.

Device name: MAC SCIENCE TMA4000S

Sample length: 20mm of

Sample width: 2mm of

Temperature rise initiation temperature: 25 DEG C

Temperature increase end temperature: 400 DEG C

Heating rate: 5 ℃/min

Atmosphere: argon gas

< Quantification of solvent-extracted Low molecular weight component in protective film >)

The protective film peeled from the laminate was cut into pieces 5mm wide and 20mm long, about 1,000mg was accurately weighed, 100g of chloroform was used as an extraction solvent, and Soxhlet extraction was performed under conditions of an extraction time of 10 hours. The component amount was precisely measured, and the protective film after extraction and drying was subjected to solvent extraction to determine the component amount (mass%) of low molecular weight by the following formula

Solvent extraction of low molecular weight component amount (mass%) in protective film = { mass before extraction (mg) -mass after extraction (mg) }/mass before extraction (mg) ×100

Further, using the extract solution obtained as described above, the peak position and peak area of each component separated by high performance liquid chromatography were determined, and the molecular weight of each component was determined by mass spectrometry (apparatus: hitachi M-1200H).

< Contact transfer amount >)

20 Sheets were stacked, cut into a laminate 100mm wide and 100mm long, and the laminate was stored at 40℃for 7 days under a load of 100g/cm ². The polyimide film was peeled from the laminate after storage and cut into pieces 5mm wide and 20mm long, and about 1,000mg was accurately weighed, and Soxhlet extraction was performed using 100g of chloroform as an extraction solvent for 10 hours. Using the obtained extraction solution, peaks of the components separated by the component separation were obtained by high performance liquid chromatography, and peak areas corresponding to peak positions of the components considered to be contained in the protective film were obtained from the measurement results of the "amount of the solvent-extracted low molecular weight component and the molecular weight in the protective film" and the calibration curve obtained in advance, and the sum of the masses of the components was converted into mg amounts per 1m ² of the polyimide film as the contact transfer amount by the area ratio.

< Initial peel Strength >

After a laminate was obtained by bonding a polyimide film and a protective film, the initial peel strength was determined by the following method using a 90 degree peel method after 1 day of lamination.

A laminate having a width of 100mm and a length of 100mm, which was cut from the center portion, the left and right end portions, the further end portions and the center middle portion of the laminate, was further cut into 4 rectangles of 25mm×100mm as samples.

The protective film side of the laminate was adhered to a sample stand of 90-degree peel jig "GT-40" manufactured by shimadzu corporation with a double-sided tape, and the peel force at the time of peeling the protective film from the laminate (polyimide film) at an angle of 90 degrees was measured by a tensile tester "Autograph AG-IS" manufactured by shimadzu corporation.

Measurement device: autograph AG-IS manufactured by Shimadzu corporation

And (3) measuring a clamp: stripping clamp GT-40 for production in the field

Measuring temperature: room temperature (25 ℃ C.)

Peeling speed: 100mm/min

Atmosphere: atmospheric air

Measuring sample width: 25mm of

< Peel Strength after 7 days of storage at 40℃under a load of 100g/cm ² >

20 Sheets were stacked, cut into a laminate 100mm wide and 100mm long, and the laminate was stored at 40℃for 7 days under a load of 100g/cm ². The laminate after storage was cut into 4 rectangles of 25mm×100mm, and the peel strength at the time of peeling the protective film from the laminate was measured for the longitudinal direction of each rectangle in the same manner as the initial peel strength, and the average value of the total 4 was obtained.

< Tensile elastic modulus of polyimide film >

Strip materials each cut 100mm×10mm in the machine direction (MD direction) and the width direction (TD direction) of the polyimide film were used as test pieces. The test piece was cut from the widthwise central portion. The tensile modulus was measured in the MD and TD directions using a tensile tester (Autograph (R) manufactured by Shimadzu corporation, model name AG-5000A) at a temperature of 25℃and a tensile speed of 50 mm/min with a chuck spacing of 40 mm.

[ Preparation of polyamic acid solution A ]

A reaction vessel equipped with a nitrogen inlet, a thermometer and a stirring bar was purged with nitrogen, and then 176.5g (0.900 mol) of 1,2,3, 4-cyclobutanetetracarboxylic dianhydride (CBDA), 31.0g (0.100 mol) of 4,4' -oxydiphthalic acid (ODPA), 160.1g (0.500 mol) of 2,2' -bistrifluoromethyl-4, 4' -diaminobiphenyl (TFMB), 113.6g (0.500 mol) of 4-amino-N- (4-aminophenyl) benzamide (DABAN) and 2000g of N, N-dimethylacetamide were added to the reaction vessel under a nitrogen atmosphere to dissolve the materials, followed by stirring at room temperature for 24 hours. Then, the resultant solution was diluted with 1000g 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 the inside of a reaction vessel equipped with a nitrogen inlet tube, a thermometer and a stirring bar was replaced with nitrogen, 461g of N, N-Dimethylacetamide (DMAC) and 64.0g (0.200 mol) of 2,2 '-bistrifluoromethyl-4, 4' -diaminobiphenyl (TFMB) were added to the reaction vessel under a nitrogen atmosphere, and TFMB was dissolved in DMAC by stirring. Then, the reaction vessel was stirred, and 89.737g (0.202 mol) of 4,4' - (2, 2-hexafluoroisopropylidene) diphthalic dianhydride (6 FDA) was added thereto over about 10 minutes under a nitrogen stream, and in this state, the temperature was adjusted to a temperature range of 20 to 40℃and the stirring was continued for 6 hours, whereby polymerization was carried out to obtain a viscous polyamic acid solution.

Then, after 410g of DMAC was added to the obtained polyamic acid solution to dilute it, 25.83g of isoquinoline was added as an imidization accelerator, and the polyamic acid solution was stirred while maintaining a temperature range of 30 to 40℃and 122.5g (1.20 mol) of acetic anhydride was slowly added dropwise thereto as an imidization agent over about 10 minutes, and then further maintained at a liquid temperature of 30 to 40℃with continuous stirring for 12 hours, to perform a chemical imidization reaction, to obtain a polyimide solution.

Then, 1000g of the polyimide solution containing the obtained imidizing agent and imidizing accelerator was transferred to a reaction vessel equipped with a stirring device and stirring blades, and 1500g of methanol was added dropwise thereto at a speed of 10 g/min while maintaining a temperature of 15 to 25℃with stirring at a speed of 120 rpm. When about 800g of methanol was added, turbidity of the polyimide solution was confirmed, and precipitation of polyimide in powder form was confirmed. Then, a total amount of 1500g of methanol was added to complete precipitation of polyimide. Then, the content of the reaction vessel was filtered by a suction filtration apparatus, and further washed and filtered with 1000g of methanol. Then, 50g of the polyimide powder thus filtered was dried at 50℃for 24 hours using a drier equipped with a local exhauster, and further dried at 260℃for 2 hours, and the remaining volatile components were removed, to obtain a polyimide powder. The reduced viscosity of the obtained polyimide powder was 5.40dl/g. Then, 40g of the obtained polyimide powder was dissolved in 300g of DMAC to obtain a polyimide solution B.

[ Preparation of polyimide solution C ]

A reaction vessel equipped with a nitrogen inlet pipe, a dean-stark pipe, a reflux pipe, a thermometer and a stirrer was charged with nitrogen, and 120.5g (0.485 mol) of 4,4 '-diaminodiphenyl sulfone (4, 4' -DDS), 51.6g (0.208 mol) of 3,3 '-diaminodiphenyl sulfone (3, 3' -DDS) and 500g of gamma-butyrolactone (GBL) were added. Then, 217.1g (0.700 mol) of 4,4' -Oxydiphthalic Dianhydride (ODPA), 223g of GBL and 260g of toluene were added at room temperature, and the mixture was heated to 160℃and heated to reflux at 160℃for 1 hour to effect imidization. After the imidization was completed, the temperature was raised to 180℃and the reaction was continued while toluene was removed. After the reaction for 12 hours, the oil bath was removed and returned to room temperature, and GBL was added so that the solid content became 20% by mass, to obtain a polyimide solution C having a reduced viscosity of 2.50 dl/g.

[ Production example 1 of polyimide film ]

The polyamic acid solution A was applied to a mirror finished stainless steel endless belt (coating width 1240 mm) as a support for polyimide film production by a die coater, and dried at 90 to 115℃for 10 minutes. After drying, the self-supporting polyamic acid film was peeled off from the support, and both ends were cut to obtain a green film.

The obtained green film was transported by a pin tenter so that the final pin pitch became 1140mm, heat-treated at stage 1 at 170℃for 2 minutes, at stage 2 at 230℃for 2 minutes, at stage 3 at 350℃for 6 minutes, cooled to room temperature in 2 minutes, and the portions of the film having poor flatness at both ends were cut off by a slitter (slitter) and rolled into a roll to obtain polyimide films 1A shown in Table 1. In the same manner as described below, the polyimide film 1B shown in table 1 was obtained by changing the polyamic acid solution a to the polyimide solution B and changing the coating thickness on the support.

[ Production example 2 of polyimide film ]

The polyamic acid solution A was applied to a polyester film (coating width: 1240 mm) having a surface roughness (Sa) of 1nm, a maximum protrusion height (Sp) of 7nm, a peak top point density (Spd) of 20/. Mu.m ² or less, and no coating layer on the surface, and dried at 90 to 115℃for 10 minutes using a comma coater. After drying, the polyimide film (containing 10 mass% of a solvent) having self-supporting properties was peeled off from the support, and both ends were cut to obtain a green film.

The obtained green film was transported by a pin tenter at a final pin pitch of 1140mm, and subjected to heat treatment at stage 1 of 170℃for 2 minutes, stage 2 of 230℃for 2 minutes, and stage 3 of 350℃for 6 minutes, to remove the solvent. Then, the film was cooled to room temperature within 2 minutes, and the portions of the film having poor flatness at both ends thereof were cut off by a slitting machine and wound into a roll shape to obtain polyimide films 2A shown in table 1. In the same manner as described below, the polyimide film 2C shown in table 1 was obtained by changing the polyamic acid solution a to the polyimide solution C and changing the coating thickness on the support.

[ Production example 3 of polyimide film ]

The polyimide solution B was applied to an unstretched polypropylene film (coating width: 450 mm) having a surface roughness (Sa) of 3nm, a maximum protrusion height (Sp) of 12nm, and a peak top density (Spd) of 25/μm ² or less, which was a part of the unstretched polypropylene film as a support, by using a comma coater, and dried at 85 to 105 ℃ for 30 minutes to obtain a two-layer film of the support and the polyimide film (containing about 8 mass% of the solvent). Next, the two films were stretched by 2.8 times in the MD direction simultaneously with the difference in peripheral speed of the rolls. Further, between the rollers having a peripheral speed difference, the polyimide film side surface of the two-layer film is disposed so as not to contact the rollers. After stretching in the MD direction, both ends of the two-layer film were sandwiched by a clip tenter, and the polyimide film was peeled off from the support of the two-layer film while carrying out heat treatment at 150 ℃ so that the final pin plate interval became 1140mm, that is, the TD direction stretching was 2.5 times, and then heat treatment was further carried out at 350 ℃ for 3 minutes, thereby removing the solvent. Then, the film was cooled to room temperature within 2 minutes, and the portions of the film having poor flatness at both ends thereof were cut off by a slitting machine and wound into a roll shape to obtain polyimide films 3B shown in table 1. In the same manner as described below, the polyimide solution B was changed to the polyimide solution C, and the coating thickness on the support was changed to obtain a polyimide film 3C shown in table 1.

Example 1

< Fabrication of laminate >)

The entire surface of the polyimide film 1A obtained in production example 1 was overlapped with the adhesive surface of a protective film (CLEAR-PET 50-06-50 manufactured by Lintec corporation) facing the polyimide film 1A, and the resultant was mounted on a roll laminator equipped with a silicone rubber roll. The laminator used was a laminator with an effective roll width of 1350mm manufactured by MCK corporation, and the lamination conditions were air source pressure: 0.5MPa, lamination speed: 50 mm/sec, roll temperature: 22 ℃, ambient temperature 22 ℃ and humidity 55% RH. The evaluation results of the obtained laminate are shown in table 3.

Examples 2 to 6

In the same manner as described below, a laminate was produced using the polyimide film shown in table 1 and the protective film shown in table 2, and the characteristics of the laminate, the protective film peeled from the laminate, and the characteristics of the polyimide film peeled from the laminate were evaluated. The results are shown in tables 3 and 4.

Comparative examples 1 to 4

In the same manner as described below, a laminate was produced using the polyimide film shown in table 1 and the protective film shown in table 2, and the characteristics of the laminate were evaluated. The results are shown in Table 3.

TABLE 1

TABLE 2

TABLE 3

TABLE 4

Industrial applicability

As described above, the laminate of the present invention can stably maintain uniform peel strength not only immediately after production but also after long-term storage, and is useful for long-term production of functional devices such as semiconductor devices, MEMS devices, and display devices, since there is no decrease in adhesion of polyimide films, plasticization, and whitening.

Claims

1. A laminate comprising a polyimide film and a protective film bonded to at least one surface of the polyimide film,

The solvent-extracted low-molecular-weight component contained in the protective film peeled from the laminate is 0.03 to 3.0 mass%,

The protective film has a base film and an adhesive layer,

The adhesive layer is an organosilicon adhesive or an acrylic adhesive,

After the laminate is stored at 40 ℃ for 7 days under a load of 100g/cm ², the peel strength of the protective film at the time of peeling the protective film from the laminate by a 90-degree peeling method is 0.06N/cm or more and 0.25N/cm or less.

2. The laminate according to claim 1, wherein the solvent-extracted low-molecular-weight component contained in the polyimide film peeled from the laminate after the laminate is stored at 40 ℃ for 7 days under a load of 100g/cm ² is 0.5 to 50mg/m ².

3. The laminate according to claim 1, wherein an initial peel strength of the protective film at the time of peeling the protective film from the laminate by a 90-degree peeling method is 0.06N/cm or more and 0.25N/cm or less.

4. The laminate according to any one of claims 1 to 3, wherein the polyimide film has a tensile elastic modulus in both the MD direction and the TD direction of 3GPa to 20 GPa.

5. The laminate according to any one of claims 1 to 3, wherein the protective film is composed of a polycondensation resin film and a binder.