JP2020037265A - Polyimide film laminate and production method of polyimide film laminate - Google Patents

Abstract

To provide a heat treatment condition under which a laminate with less defects and with higher quality can be made, with respect to a film laminate in which layers are laminated via a reactive compound layer.SOLUTION: With respect to a polyimide film laminate which is obtained by heat-treating a polyimide film laminate comprising a plurality of polyimide films stacked together, a higher quality polyimide film laminate can be obtained by selectively using heat treatment temperatures in adhesion of the plurality of polyimide films with a reactive compound according to a moisture content of the polyimide film.SELECTED DRAWING: None

Description

  The present invention relates to a polyimide film laminate obtained by reacting a reactive compound layer by heat treatment of a polyimide film multilayer having a structure in which a polyimide film and a reactive compound layer are alternately stacked, and a method for producing the same.

  The present invention provides a flexible printed circuit board (hereinafter, referred to as an "FPC board") formed by bonding a support plate or a reinforcing plate, particularly a plurality of polyimide films, which are used by being adhered to the FPC board in order to maintain the strength. The present invention relates to a polyimide film laminate and a method for producing the same.

Representative examples of a film in which a heat-curable adhesive is provided on one or both sides of a single-layer or multilayer polyimide film include “coverlay film” and “TAB (Tape Automated Bonding) film”. Can be As shown in FIG. 1 (a), the adhesive used for these films is applied on a base film 11 made of a polyimide film and then dried to obtain an adhesive in a semi-cured state (B stage). Layer 12 is provided. On the surface of the adhesive layer 12, a separator 13 is usually further laminated. The laminate is stored in a form having an adhesive layer which is in a semi-cured state before use. Examples of the adhesive layer of the polyimide film in another form include a prepreg obtained by impregnating an adhesive varnish with a reinforcing substrate such as a glass cloth and drying. As for the prepreg, the adhesive is stored in the state of the B stage. Then, as shown in FIG. 1B, the base film 11 of the coverlay film or the TAB film is applied to an object such as an FPC board 14 via an adhesive layer 2 (made of an adhesive or a prepreg). The base film 11 is adhered to an object such as the FPC board 14 by overlapping, heating, and pressing. Further, as shown in FIG. 2, an FPC board in which a metal foil 23 such as a copper foil and a polyimide film 11 are bonded with an adhesive 22 is also known, but in these bondings, a metal foil and a polyimide film are used. After laminating, it is necessary to perform heat aging.

  By the way, the thickness of the FPC board is usually small (for example, 12.5 to 100 μm). However, when the thickness of the substrate is thin, inconvenience is likely to occur in the switch section and the connector section. For this reason, conventionally, an FPC board made of a polyimide film including a part where this problem easily occurs or a part where this problem easily occurs is conventionally fixed to a support via a heat-curable adhesive (called a bonding sheet). Is being done. In this case, it is a general bonding condition to heat and press at 150 to 180 ° C. for 15 to 45 minutes under a pressure of 1 to 3 MPa. A single-layer polyimide film is generally used as a support plate used to support or reinforce the FPC board. A single-layer polyimide film having a thickness of 225 μm or less is widely and generally commercially available, and this commercially available single-layer polyimide film is used as a support plate. Representative examples of these single-layer polyimide films include Kapton H or V type (manufactured by Toray DuPont), Upilex S type (manufactured by Ube Industries), Apical AH or NPI type (manufactured by Co., Ltd.). Polyimide films commercially available under trade names such as Kaneka Corporation. A single-layer polyimide film has a constant hardness and stiffness depending on each product. However, depending on the application, even if the thickness is the same, rigidity may be required more than that of a single layer.

Further, the polyimide film is mainly produced by solution casting by casting, and it is difficult to produce a thick film due to its production method, or its productivity is extremely poor.

  In order to solve the problems of rigidity and film thickness, a polyimide film laminate in which a plurality of polyimide films are bonded is used. As a method of manufacturing a polyimide film laminate, a method of laminating a polyimide film by a hot press via a thermoplastic polyimide, a method of applying a reactive compound on one or both surfaces of the polyimide film, laminating, a method of reacting by heating, and the like. No.

  When producing a polyimide film laminate by applying a reactive compound to one or both surfaces of the polyimide film, it is convenient and common to use heating for the reaction of the applied compound, When heated rapidly, water (e.g., blisters) may occur between the polyimide film layers due to evaporation of moisture contained in the polyimide film. In particular, when the number of the polyimide films is three or more, the water evaporated from the polyimide film disposed at the center is less likely to be released to the outside of the laminate, and the generation of uki (blister) is remarkable. If foreign matter is mixed between the film layers, a tent (blister) is generated due to the tent effect. However, the uki, which is the subject of the present invention, is caused by the moisture radiated from the film, and there is no nucleus foreign matter inside the uki.

Japanese Patent Application No. 2006-090555

  The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, the polyimide film and the reactive compound layer were alternately stacked. By adjusting the heating temperature according to the amount of water contained, it was found that the formation of uki (blisters) between the superimposed polyimides could be suppressed, and in addition, this method was widely applied to all film laminates formed via reactive compounds. The present invention was found to be applicable to the present invention.

That is, the present invention has the following configurations.
[1] A polyimide film laminate having a structure in which a plurality of polyimide film layers and reactive compound layers are alternately stacked, and having no foreign substance core existing between the polyimide film layers and having a diameter of 100 μm or more and 5 mm or less (blister) ) Is not more than ((number of polyimide film layers −1) × 5) per 100 cm 2.
[2] The polyimide film laminate according to [1], wherein the thickness of the reactive compound layer is 5 nm or more and 800 nm or less.
[3] In the method for producing a polyimide film laminate obtained by heat-treating a polyimide film laminate having a structure in which a plurality of polyimide film layers and reactive compound layers are alternately stacked, the polyimide film laminate is included in the polyimide film layer. A method for producing a polyimide film laminate, wherein the heat treatment is performed at 180 ° C. or lower when the average water content is 1.5% by mass or more, and at 180 ° C. or higher when the average water content is less than 1.5% by mass.
[4] The heat treatment is performed after the polyimide film layers and the reactive compound layers are alternately stacked so that the peel strength between the respective polyimide film layers in the polyimide film multilayer body before the heat treatment is 2 N / cm or less. The method for producing a polyimide film laminate according to [3].
[5] The polyimide film laminate according to [3] or [4], wherein the reactive compound forming the reactive compound layer is liquid at 40 ° C. and has a boiling point of 100 ° C. or higher. Manufacturing method.

  The method for producing a polyimide film laminate of the present invention can suppress generation of uki (blister) due to evaporation of water contained in the polyimide film, and as a result, can obtain a high-quality film laminate with few defects.

FIG. 1 is a schematic cross-sectional view of a PI film (a) provided with an adhesive layer on one side and an FPC board (b) on which the PI film is bonded. FIG. 2 is a schematic cross-sectional view of an FPC board in which a copper foil and a PI film are bonded. FIG. 3 is a schematic cross-sectional view of a stiffener obtained by laminating two thin PI films. FIG. 4 is a schematic configuration diagram showing an example of an apparatus used for a method of treating a film with a silane coupling agent via a gas phase in the present invention. FIG. 5 is a schematic diagram illustrating an example of a silane coupling agent processing apparatus.

<Polyimide film multilayer>
The polyimide film multilayer body in the present invention refers to a polyimide film coated with a reactive compound on one or both sides, which is superimposed or temporarily adhered, regardless of the superposition method or the temporary adhesion method. The number of polyimide films to be superposed may be any number as long as it is two or more.

<Polyimide film laminate>
The polyimide film laminate in the present invention refers to a laminate obtained by heat-treating a polyimide film multilayer body, and the number of laminated layers may be any number as long as it is two or more.

<Polyimide film>
The polyimide film layer of the present invention comprises a polyimide film. The thickness of the polyimide film of the present invention is preferably 3 μm or more, more preferably 11 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 still more preferably 90 μm or less from the demand for a flexible electronic device.
The area of the polyimide film of the present invention is preferably large from the viewpoint of production efficiency and cost of the laminate and the flexible electronic device. It is preferably at least 1,000 square cm, more preferably at least 1500 square cm, even more preferably at least 2,000 square cm.

  In the present invention, an aromatic polyimide, an alicyclic polyimide, a polyamideimide, a polyetherimide, or the like can be used as the polyimide film. More preferably, it refers to a polymer containing 50% or more of a polyimide skeleton.

  In general, a polyimide film is prepared by applying a polyamic acid (polyimide precursor) solution obtained by reacting a diamine and a tetracarboxylic acid in a solvent onto a support for producing a polyimide film and drying the green film (“precursor film”). Or "polyamic acid film"), and furthermore, a green film is subjected to a high-temperature heat treatment on a support for preparing a polyimide film or in a state of being peeled off from the support to carry out a dehydration ring closure reaction.

  There is no particular limitation on the diamines constituting the polyamic acid, and aromatic diamines, aliphatic diamines, alicyclic diamines, and the like that are usually used in the synthesis of polyimide can be used. From the viewpoint of heat resistance, aromatic diamines are preferable, and among the aromatic diamines, aromatic diamines having a benzoxazole structure are more preferable. When an aromatic diamine having a benzoxazole structure is used, it becomes possible to exhibit high heat resistance, high elastic modulus, low heat shrinkage, and low coefficient of linear expansion. The diamines may be used alone or in combination of two or more.

  In general, a polyimide film is prepared by applying a polyamic acid (polyimide precursor) solution obtained by reacting a diamine and a tetracarboxylic acid in a solvent onto a support for producing a polyimide film and drying the green film (“precursor film”). Or "polyamic acid film"), and furthermore, a green film is subjected to a high-temperature heat treatment on a support for preparing a polyimide film or in a state of being peeled off from the support to carry out a dehydration ring closure reaction.

  There is no particular limitation on the diamines constituting the polyamic acid, and aromatic diamines, aliphatic diamines, alicyclic diamines, and the like that are usually used in the synthesis of polyimide can be used. From the viewpoint of heat resistance, aromatic diamines are preferable, and among the aromatic diamines, aromatic diamines having a benzoxazole structure are more preferable. When an aromatic diamine having a benzoxazole structure is used, it becomes possible to exhibit high heat resistance, high elastic modulus, low heat shrinkage, and low coefficient of linear expansion. The diamines may be used alone or in combination of two or more.

  The aromatic diamine having a benzoxazole structure is not particularly limited, and examples thereof include 5-amino-2- (p-aminophenyl) benzoxazole, 6-amino-2- (p-aminophenyl) benzoxazole, -Amino-2- (m-aminophenyl) benzoxazole, 6-amino-2- (m-aminophenyl) benzoxazole, 2,2'-p-phenylenebis (5-aminobenzoxazole), 2,2 ' -P-phenylenebis (6-aminobenzoxazole), 1- (5-aminobenzoxazolo) -4- (6-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 and the like can be mentioned.

  Examples of aromatic diamines other than the above-mentioned aromatic diamines having a benzoxazole structure include 2,2′-dimethyl-4,4′-diaminobiphenyl and 1,4-bis [2- (4-aminophenyl). ) -2-Propyl] benzene (bisaniline), 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) phene L] propane, 2,2-bis [4- (3-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, m-phenylenediamine, o-phenylenediamine, p-phenylene Diamine, m-aminobenzylamine, p-aminobenzylamine, 3,3'-diaminodiphenylether, 3,4'-diaminodiphenylether, 4,4'-diaminodiphenylether, 3,3'-diaminodiphenylsulfide, 3,3 '-Diaminodiphenylsulfoxide, 3,4'-diaminodiphenylsulfoxide, 4,4'-diaminodiphenylsulfoxide, 3,3'-diaminodiphenylsulfone, 3,4'-diaminodiphenylsulfone, 4,4'-diaminodiphenylsulfone , 3,3'-diaminobenzopheno , 3,4'-diaminobenzophenone, 4,4'-diaminobenzophenone, 3,3'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, bis [4- (4-aminophenoxy ) Phenyl] methane, 1,1-bis [4- (4-aminophenoxy) phenyl] ethane, 1,2-bis [4- (4-aminophenoxy) phenyl] ethane, 1,1-bis [4- ( 4-aminophenoxy) phenyl] propane, 1,2-bis [4- (4-aminophenoxy) phenyl] propane, 1,3-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 1,1-bis [4- (4-aminophenoxy) phenyl] butane, 1,3- Bis [4- (4-aminophenoxy) phenyl] butane, 1,4-bis [4- (4-aminophenoxy) phenyl] butane, 2,2-bis [4- (4-aminophenoxy) phenyl] butane, 2,3-bis [4- (4-aminophenoxy) phenyl] butane, 2- [4- (4-aminophenoxy) phenyl] -2- [4- (4-aminophenoxy) -3-methylphenyl] propane , 2,2-bis [4- (4-aminophenoxy) -3-methylphenyl] propane, 2- [4- (4-aminophenoxy) phenyl] -2- [4- (4-aminophenoxy) -3 , 5-Dimethylphenyl] propane, 2,2-bis [4- (4-aminophenoxy) -3,5-dimethylphenyl] propane, 2,2-bis [4- (4-aminophenoxy) phenyl -1,1,1,3,3,3-hexafluoropropane, 1,4-bis (3-aminophenoxy) benzene, 1,3-bis (3-aminophenoxy) benzene, 1,4-bis (4 -Aminophenoxy) benzene, 4,4'-bis (4-aminophenoxy) biphenyl, bis [4- (4-aminophenoxy) phenyl] ketone, bis [4- (4-aminophenoxy) phenyl] sulfide, bis [ 4- (4-aminophenoxy) phenyl] sulfoxide, bis [4- (4-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] ether, bis [4- (4-aminophenoxy) Phenyl] ether, 1,3-bis [4- (4-aminophenoxy) benzoyl] benzene, 1,3-bis [4- (3-aminophen Xy) 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-dimethyl) Benzyl) 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, , 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'-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-phenoxybenzoyl) benzene, 1,4- Bis (4-amino-5-phenoxybenzoyl) benzene, 1,3-bis (3-amino-4-biphenoxyben) Yl) benzene, 1,4-bis (3-amino-4-biphenoxybenzoyl) benzene, 1,3-bis (4-amino-5-biphenoxybenzoyl) benzene, 1,4-bis (4-amino- 5-biphenoxybenzoyl) benzene, 2,6-bis [4- (4-amino-α, α-dimethylbenzyl) phenoxy] benzonitrile, and part or all of the hydrogen atoms on the aromatic ring of the aromatic diamine Is a halogen atom, an alkyl group having 1 to 3 carbon atoms or an alkoxyl group, a cyano group, or a halogenated alkyl having 1 to 3 carbon atoms in which part or all of the hydrogen atoms of an alkyl group or an alkoxyl group are substituted with a halogen atom. And an aromatic diamine substituted with a group or an alkoxyl group.

Examples of the aliphatic diamines include 1,2-diaminoethane, 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane, and 1,8-diaminooctane.
Examples of the alicyclic diamines include 1,4-diaminocyclohexane and 4,4′-methylenebis (2,6-dimethylcyclohexylamine).
The total amount of diamines (aliphatic diamines and alicyclic diamines) other than aromatic diamines is preferably 20% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less of all diamines. It is. In other words, the content of the aromatic diamines is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more of all the diamines.

  Examples of the tetracarboxylic acids constituting the polyamic acid include aromatic tetracarboxylic acids (including their acid anhydrides), aliphatic tetracarboxylic acids (including their acid anhydrides), and alicyclic tetracarboxylic acids commonly used in the synthesis of polyimide. Acids (including their acid anhydrides) can be used. Among them, aromatic tetracarboxylic acid anhydrides and alicyclic tetracarboxylic acid anhydrides are preferable, from the viewpoint of heat resistance, aromatic tetracarboxylic acid anhydrides are more preferable, and from the viewpoint of light transmittance, alicyclic ring is preferable. Aromatic tetracarboxylic acids are more preferred. When these are acid anhydrides, the number of anhydride structures in the molecule may be one or two, but those having two anhydride structures (dianhydride) are preferred. Good. The tetracarboxylic acids may be used alone or in combination of two or more.

Examples of the alicyclic tetracarboxylic acids include alicyclic tetracarboxylic acids such as cyclobutanetetracarboxylic acid, 1,2,4,5-cyclohexanetetracarboxylic acid, and 3,3 ′, 4,4′-bicyclohexyltetracarboxylic acid. Carboxylic acids and their anhydrides. Among them, dianhydrides having two anhydride structures (for example, cyclobutanetetracarboxylic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, 3,3 ′, 4,4 '-Bicyclohexyltetracarboxylic dianhydride and the like) are preferred. The alicyclic tetracarboxylic acids may be used alone or in combination of two or more.
When importance is placed on transparency, the alicyclic tetracarboxylic acids are, for example, preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more of all the tetracarboxylic acids.

The aromatic tetracarboxylic acids are not particularly limited, but are preferably pyromellitic acid residues (that is, those having a structure derived from pyromellitic acid), and more preferably acid anhydrides thereof. Examples of such aromatic tetracarboxylic acids include pyromellitic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 4,4′-oxydiphthalic dianhydride, , 3 ', 4,4'-benzophenonetetracarboxylic dianhydride, 3,3', 4,4'-diphenylsulfonetetracarboxylic dianhydride, 4,4 '-(2,2-hexafluoroisopropylidene ) Diphthalic dianhydride, 2,2-bis [4- (3,4-dicarboxyphenoxy) phenyl] propanoic anhydride and the like.
When importance is placed on heat resistance, the aromatic tetracarboxylic acids are, for example, preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more of all the tetracarboxylic acids.

  The polyimide resin in the present invention is preferably transparent in some applications. As acid components used for the synthesis of the precursor, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,4,5-cyclopentanetetracarboxylic dianhydride, 1,2,4 5-cyclohexanetetracarboxylic dianhydride, bicyclo [2,2,1] heptane-2,3,5,6-tetracarboxylic dianhydride, bicyclo [2,2,2] octane-2,3,5 , 6-tetracarboxylic dianhydride, 3,3 ′, 4,4′-bicyclohexyltetracarboxylic dianhydride, 1,2,4-cyclohexanetricarboxylic anhydride, norbornane-2-spiro-α-cyclo Pentanone-α′-spiro-2 ″ -norbornane-5,5 ″, 6,6 ″ -tetracarboxylic dianhydride (also known as “norbornane-2-spiro-2′-cyclopentanone-5 ′ -Spiro- 2 ″ -norbornane-5,5 ″, 6,6 ″ -tetracarboxylic dianhydride ”), methylnorbornane-2-spiro-α-cyclopentanone-α′-spiro-2 ″-( Methylnorbornane) -5,5 ″, 6,6 ″ -tetracarboxylic dianhydride, norbornane-2-spiro-α-cyclohexanone-α′-spiro-2 ″ -norbornane-5,5 ″, 6,6 "-tetracarboxylic dianhydride (also known as" norbornane-2-spiro-2'-cyclohexanone-6'-spiro-2 "-norbornane-5,5", 6,6 "-tetra Carboxylic acid dianhydride "), methyl norbornane-2-spiro-α-cyclohexanone-α'-spiro-2"-(methyl norbornane) -5,5 ", 6,6" -tetracarboxylic dianhydride Object, norbornane- -Spiro-α-cyclopropanone-α′-spiro-2 ″ -norbornane-5,5 ″, 6,6 ″ -tetracarboxylic dianhydride, norbornane-2-spiro-α-cyclobutanone-α '-Spiro-2' '-norbornane-5,5' ', 6,6' '-tetracarboxylic dianhydride, norbornane-2-spiro-α-cycloheptanone-α'-spiro-2' '- Norbornane-5,5 ″, 6,6 ″ -tetracarboxylic dianhydride, norbornane-2-spiro-α-cyclooctanone-α′-spiro-2 ″ -norbornane-5,5 ″, 6,6 ″ -tetracarboxylic dianhydride, norbornane-2-spiro-α-cyclononanone-α′-spiro-2 ″ -norbornane-5,5 ″, 6,6 ″ -tetracarboxylic dianhydride Anhydride, norbornane-2-spi B-α-cyclodecanone-α′-spiro-2 ″ -norbornane-5,5 ″, 6,6 ″ -tetracarboxylic dianhydride, norbornane-2-spiro-α-cycloundecanone-α ′ -Spiro-2 ″ -norbornane-5,5 ″, 6,6 ″ -tetracarboxylic dianhydride, norbornane-2-spiro-α-cyclododecanone-α′-spiro-2 ″ -norbornane -5,5 ″, 6,6 ″ -tetracarboxylic dianhydride, norbornane-2-spiro-α-cyclotridecanone-α′-spiro-2 ″ -norbornane-5,5 ″, 6 , 6 ″ -tetracarboxylic dianhydride, norbornane-2-spiro-α-cyclotetradecanone-α′-spiro-2 ″ -norbornane-5,5 ″, 6,6 ″ -tetracarboxylic acid Acid dianhydride, norbornane-2- Pyro-α-cyclopentadecanone-α′-spiro-2 ″ -norbornane-5,5 ″, 6,6 ″ -tetracarboxylic dianhydride, norbornane-2-spiro-α- (methylcyclo (Pentanone) -α′-spiro-2 ″ -norbornane-5,5 ″, 6,6 ″ -tetracarboxylic dianhydride, norbornane-2-spiro-α- (methylcyclohexanone) -α′- Spiro-2 ″ -norbornane-5,5 ″, 6,6 ″ -tetracarboxylic dianhydride and the like are exemplified, and particularly preferred is 1,2,3,4-cyclobutanetetracarboxylic dianhydride. Anhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, and 3,3 ′, 4,4′-bicyclohexyltetracarboxylic dianhydride. These aliphatic carboxylic acids may be used alone or in combination of two or more. On the other hand, those containing an unsaturated bond, such as bicyclo [2,2,2] oct-7-ene-2,3,5,6-tetracarboxylic dianhydride, are colored at the time of heat treatment, and the optical properties of the film are reduced. It is not preferred because it tends to lower.

When the diamine component used in the synthesis of the polyimide resin or its precursor of the present invention is exemplified as a diamine compound, 1,3-phenylenediamine, 1,4-phenylenediamine, 2,4-diaminotoluene, 2,6-diamino Toluene, 3,4-diaminotoluene, 4,5-dimethyl-1,2-phenylenediamine, 2,5-dimethyl-1,4-phenylenediamine, 2,6-dimethyl-1,4-phenylenediamine, 2, 3,5,6-tetramethyl-1,4-phenylenediamine, 3-aminobenzylamine, m-xylylenediamine, p-xylylenediamine, 1,5-diaminonaphthalene, 2,2′-dimethylbiphenyl-4 , 4′-diamine, 2,2′-bis (trifluoromethyl) benzidine, 3,3′-dimethoxybenzidine, 4,4'-diaminooctafluorobiphenyl, 3,3'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, 4,4'-methylenebis (2,6-diethylaniline), 4, 4'-methylenebis (2-ethyl-6-methylaniline), 4,4'-ethylenedianiline, 4,4'-diaminodiphenylether, 3,4'-diaminodiphenylether, 3,3'-diaminodiphenylether, 2, 2'-bis (trifluoromethyl) -4,4'-diaminodiphenyl ether, 1,3-bis (4-aminophenoxy) benzene, 1,3-bis (3-aminophenoxy) benzene, 1,4-bis ( 4-aminophenoxy) benzene, 1,4-bis (4-amino-2-trifluoromethyl) Phenoxy) benzene, 4,4′-bis (4-aminophenoxy) biphenyl, 4,4′-diamino-3,3′-dimethyldiphenylmethane, bis [4- (4-aminophenoxy) phenyl] sulfone, bis [4 -(3-Aminophenoxy) phenyl] sulfone, 2,2-bis (4-aminophenyl) hexafluoropropane, 2,2-bis (3-aminophenyl) hexafluoropropane, 2,2′-bis [4- (4-aminophenoxy) phenyl] propane, 2,2′-bis [4- (4-aminophenoxy) phenyl] hexafluoropropane, 2,2-bis (3-amino-4-methylphenyl) hexafluoropropane, α, α'-bis (4-aminophenyl) -1,4-diisopropylbenzene, bis (2-aminophenyl) sulfur , Bis (4-aminophenyl) sulfide, 3,3'-diaminodiphenylsulfone, 4,4'-diaminodiphenylsulfone, 4,4'-diaminodiphenylsulfide, 4,4'-diaminobenzophenone, 3,3 ' -Diaminobenzophenone, 4,4'-diaminobenzanilide, 1,4-bis (4-aminophenoxy) benzene, bis (4-aminophenyl) terephthalate, 2,7-diaminofluorene, 9,9-bis (4- And aromatic diamines such as (aminophenyl) fluorene. As the aliphatic diamine, 1,3-diaminocyclohexane, 1,4-diaminocyclohexane, 1,3-bis (aminomethyl) cyclohexane, 1,1-bis (4-aminophenyl) cyclohexane, 4,4′-diaminodicyclohexyl Methane, 4,4'-methylenebis (2-methylcyclohexylamine), 4,4'-methylenebis (2,6-dimethylcyclohexylamine), 4,4'-diaminodicyclohexylpropane, bicyclo [2.2.1] heptane -2,3-diamine, bicyclo [2.2.1] heptane-2,5-diamine, bicyclo [2.2.1] heptane-2,6-diamine, bicyclo [2.2.1] heptane-2 , 7-Diamine, 2,3-bis (aminomethyl) -bicyclo [2.2.1] heptane, 2,5-bis ( Minomethyl) -bicyclo [2.2.1] heptane, 2,6-bis (aminomethyl) -bicyclo [2.2.1] heptane, 3 (4), 8 (9) -bis (aminomethyl) tricyclo [ 5.2.1.0 (2,6)] decane and the like. Of these, p-phenylenediamine, 2,2'-dimethylbiphenyl-4,4'-diamine, 2,2'-bis (trifluoromethyl) benzidine, and 2,2'-bis (trifluoro Methyl) -4,4′-diaminodiphenyl ether, 1,4-bis (4-amino-2-trifluoromethylphenoxy) benzene, 1,4-diaminocyclohexane, 4,4′-diaminodicyclohexylmethane, 4,4 ′ -Methylenebis (2-methylcyclohexylamine) and 4,4'-methylenebis (2,6-dimethylcyclohexylamine). The above amine components may be used alone or in combination of two or more.

  It is preferable that the polyimide film of the present invention has a glass transition temperature of 250 ° C. or higher, preferably 300 ° C. or higher, more preferably 350 ° C. or higher, or no glass transition point is observed in a region of 500 ° C. or lower. The glass transition temperature in the present invention is determined by differential thermal analysis (DSC).

    The linear expansion coefficient (CTE) of the polyimide film of the present invention is preferably from -5 ppm / K to +20 ppm / K, more preferably from -5 ppm / K to +15 ppm / K, and still more preferably from 1 ppm / K to +10 ppm. / K. When the CTE is within the above range, the difference in linear expansion coefficient between the support and the general support can be kept small, and even when subjected to a process of applying heat, the support made of the polyimide film and the inorganic support (for example, an FPC substrate) can be formed. Peeling can be avoided. In addition, the coefficient of linear expansion of the polyimide film in the present invention in question uses an average value between 30 and 200 ° C., but the temperature range of interest varies depending on the application, and in consideration of the high-temperature process, When examining the range of 30 ° C. to 400 ° C., the range may be 100 ° C. to 400 ° C. When examining the range of 50 ° C. to 280 ° C. with the reflow process in mind, the operating temperature range is −50 ° C. to 150 ° C. The range of ° C may be emphasized.

  The breaking strength of the polyimide film in the present invention is 60 MPa or more, preferably 120 MPa or more, and more preferably 240 MPa or more. The upper limit of the breaking strength is not limited, but is practically less than about 1000 MPa. Here, the breaking strength of the polyimide film means an average value in the length direction and the width direction of the polyimide film.

The thickness unevenness of the polyimide film in the present invention is preferably 20% or less, more preferably 12% or less, further preferably 7% or less, and particularly preferably 4% or less. If the thickness unevenness exceeds 20%, it tends to be difficult to apply to a narrow portion. The thickness unevenness of the film can be determined based on the following equation, for example, by randomly extracting about 10 points from the film to be measured using a contact-type film thickness meter and measuring the film thickness.
Unevenness of film thickness (%)
= 100 x (maximum film thickness-minimum film thickness) ÷ average film thickness

  The polyimide film in the present invention is preferably obtained in a form of being wound as a long polyimide film having a width of 300 mm or more and a length of 10 m or more at the time of its production, and a roll-shaped polyimide wound on a winding core. More preferably, it is in the form of a film.

  In a polyimide film, in order to secure handling properties and productivity, it is preferable to add and contain a lubricant (particles) in the film to impart fine irregularities to the surface of the polyimide film to secure slipperiness. The lubricating material (particle) is preferably a fine particle made of an inorganic substance, and is composed of metal, metal oxide, metal nitride, metal carbide, metal salt, phosphate, carbonate, talc, mica, clay, and others. Particles made of clay minerals and the like can be used. Preferably, metal oxides such as silicon oxide, calcium phosphate, calcium hydrogen phosphate, calcium dihydrogen phosphate, calcium pyrophosphate, hydroxyapatite, calcium carbonate, and glass filler, phosphates, and carbonates can be used. The lubricating material may be only one kind or two or more kinds.

  The volume average particle diameter of the lubricant (particles) is usually 0.001 to 10 μm, preferably 0.03 to 2.5 μm, more preferably 0.05 to 0.7 μm, and still more preferably 0.05 to 0.3 μm. Such a volume average particle diameter is based on a measured value obtained by a light scattering method. If the particle size is smaller than the lower limit, industrial production of the polyimide film becomes difficult, and if the particle size exceeds the upper limit, the surface irregularities become too large and the bonding strength is weakened, which may cause practical problems.

  The amount of the lubricant added is 0.02 to 50% by mass, preferably 0.04 to 3% by mass, more preferably 0.08 to 1.2% by mass based on the polymer component in the polyimide film. % By mass. If the amount of the lubricant is too small, it is difficult to expect the effect of the addition of the lubricant, and there is a case where the securing of the slipperiness is not so great and may hinder the production of the polyimide film.If the amount is too large, the surface unevenness of the film becomes too large. However, even if the slip property is ensured, problems such as a decrease in smoothness, a decrease in the breaking strength and breaking elongation of the polyimide film, and an increase in the CTE may be caused.

  When a lubricant (particles) is added to or contained in the polyimide film, the lubricant may be a single-layer polyimide film in which the lubricant is uniformly dispersed.For example, one surface is formed of a polyimide film containing the lubricant, Even if the other surface does not contain a lubricant, it may be a polyimide film of a lubricant concentration gradient type composed of a polyimide film having a small lubricant content. In such a lubricant concentration gradient type film, fine unevenness is imparted to the surface of one layer (film), so that the layer (film) can secure slipperiness, and good handling properties and productivity can be obtained. Can be secured.

Lubricant concentration gradient type polyimide film, in the case of a film manufactured by a melt drawing film forming method, for example, first, a film is formed using a polyimide film raw material not containing a lubricant, and at least on one side of the film in the process, It can be obtained by applying a resin layer containing a lubricant. Of course, conversely, a film is formed using a polyimide film raw material containing a lubricant, and during the process, or after the film formation is completed, a polyimide film raw material containing no lubricant is applied to obtain a film. I can do it.
The same applies to a polyimide film obtained by a solution casting method such as a polyimide film. For example, as a polyamic acid solution (polyimide precursor solution), a lubricant (preferably having an average particle size of 0.05 to 2) is used. 0.02% by mass to 50% by mass (preferably 0.04 to 3% by mass, more preferably 0.08 to 1.2% by mass) with respect to the polymer solid content in the polyamic acid solution. The polyamic acid solution and a lubricant containing no or a small amount thereof (preferably less than 0.02% by mass, more preferably less than 0.01% by mass based on the polymer solid content in the polyamic acid solution) It can be produced using two kinds of polyamic acid solutions.

The method of laminating (laminating) the lubricant concentration gradient type polyimide film is not particularly limited as long as there is no problem in the adhesion between the two layers, and is a method in which the adhesion is performed without an adhesive layer or the like. I just need.
In the case of a polyimide film, for example, i) a method of preparing one polyimide film and then continuously applying the other polyamic acid solution on the polyimide film to imidize the polyimide film, ii) casting one polyamic acid solution After preparing the polyamic acid film, the other polyamic acid solution is continuously applied on the polyamic acid film, and then imidized, iii) co-extrusion method, iv) no or no lubricant is contained. A method in which a polyamic acid solution containing a large amount of a lubricant is applied on a film formed of a small amount of a polyamic acid solution by spray coating, T-die coating, or the like, and imidization is performed can be exemplified. In the present invention, it is preferable to use the above methods i) to ii).

  The ratio of the thickness of each layer in the lubricant concentration gradient type polyimide film is not particularly limited, but the polymer layer containing a large amount of the lubricant is the (a) layer, and the lubricant is not contained or the content thereof is small. When the polymer layer is the (b) layer, the ratio of the (a) layer / (b) layer is preferably 0.05 to 0.95. When the ratio of the (a) layer / (b) layer exceeds 0.95, the smoothness of the (b) layer tends to be lost, while when it is less than 0.05, the effect of improving the surface properties is insufficient and the slipperiness is lost. May be asked.

<Surface activation treatment of polyimide film>
The polyimide film used in the present invention is preferably subjected to a surface activation treatment. By the surface activation treatment, the surface of the polyimide film is modified into a state in which a functional group is present (a so-called activated state), and the affinity with the silane coupling agent is improved.
The surface activation treatment in the present invention is a dry or wet surface treatment. As the dry treatment of the present invention, a treatment for irradiating the surface with an active energy ray such as an ultraviolet ray, an electron beam, or an X-ray, a corona treatment, a vacuum plasma treatment, a normal pressure plasma treatment, a flame treatment, an itro treatment, or the like can be used. . Examples of the wet treatment include a treatment in which the film surface is brought into contact with an acid or alkali solution. The surface activation treatment preferably used in the present invention is a plasma treatment, which is a combination of a plasma treatment and a wet acid treatment.

  The plasma treatment is not particularly limited, but includes RF plasma treatment in a vacuum, microwave plasma treatment, microwave ECR plasma treatment, atmospheric pressure plasma treatment, corona treatment, etc. Includes ion implantation using a source, processing using the PBII method, flame processing exposed to thermal plasma, and itro processing. Among these, RF plasma treatment, microwave plasma treatment, and atmospheric pressure plasma treatment in a vacuum are preferable.

Appropriate conditions for the plasma treatment include oxygen plasma, plasma including fluorine such as CF4 and C2F6, which is known to have a high etching effect, or physical such as Ne, Ar, Kr, Xe, or plasma. It is desirable to use a plasma treatment which gives a high energy to the polymer surface and has a high effect of physically etching. In addition, it is also preferable to add a plasma such as CO ₂ , CO, H ₂ , N ₂ , NH ₄ , and CH ₄ , or a mixed gas thereof, or further add steam. In addition to these, OH, N ₂ , N, CO, CO ₂ , H, H ₂ , O ₂ , NH, NH ₂ , NH ₃ , COOH, NO, NO ₂ , He, Ne, Ar, Kr, Xe, CH ₂ O, Si (OCH ₃ ) ₄ , Si (OC ₂ H ₅ ) ₄ , C ₃ H ₇ Si (OCH ₃ ) ₃ , C ₃ H ₇ Si (OC ₂ H ₅ ) ₃ It is necessary to create a plasma that contains one or more components as a gas or as a decomposition product in the plasma. In the case of processing in a short time, plasma with high energy density of plasma, high kinetic energy of ions in the plasma, and plasma with high number density of active species are desirable. There are limits to increasing density. When oxygen plasma is used, surface oxidation proceeds, which is good in terms of generation of OH groups, but it is easy to form a surface with poor adhesion to the film itself, and the surface roughness (roughness) increases, Adhesion is also poor.
In addition, in the case of plasma using Ar gas, the effect of purely physical collision occurs on the surface, and in this case as well, the roughness of the surface increases. Considering these comprehensively, microwave plasma processing, microwave ECR plasma processing, plasma irradiation with an ion source that can easily implant high-energy ions, and PBII method are also desirable.

Such a surface activation treatment cleans the polymer surface and produces more active functional groups. The generated functional group is bonded to the coupling agent layer by a hydrogen bond or a chemical reaction, so that the polyimide film layer and the coupling agent layer can be firmly bonded.
In the plasma treatment, an effect of etching the polyimide film surface can also be obtained. In particular, in a polyimide film containing a relatively large amount of lubricant particles, protrusions due to the lubricant may inhibit adhesion between the films. In this case, if the polyimide film surface is thinly etched by plasma treatment to expose a part of the lubricant particles and then treated with hydrofluoric acid, it is possible to remove the lubricant particles near the film surface.

  The surface activation treatment may be performed on only one side of the polyimide film, or may be performed on both sides. When plasma treatment is performed on one side, by placing the polyimide film on one side of the electrode by plasma treatment with a parallel plate type electrode, it is possible to perform plasma treatment only on the side of the polyimide film that is not in contact with the electrode. it can. If the polyimide film is placed so as to be electrically floated in the space between the two electrodes, plasma treatment can be performed on both surfaces. In addition, one-sided processing can be performed by performing plasma processing in a state where a protective film is attached to one side of the polyimide film. In addition, a PET film or an olefin film with an adhesive can be used as the protective film.

<Surface roughness of polyimide film>
The surface roughness Ra of the polyimide film in the present invention is desirably 70 nm or less, more desirably 30 nm or less, and further desirably 1.5 nm or less. When Ra is larger than 70 nm, when a plurality of polyimide films are superimposed via the reactive compound layer, it causes a coating unevenness of the reactive compound and a peeling unevenness due thereto.

<Reactive compound>
The reactive compound in the present invention, a compound having an unsaturated double bond, a compound having an epoxy group, a compound having an amino group, a compound having a carboxyl group, a compound having a hydroxyl group, an isocyanate compound, a compound having a silanol group, And the like. The invention is preferably applicable to reactive compounds which are preferably liquid at 25 ° C.

  The reactive compound in the present invention preferably has a boiling point of 130 ° C or higher, more preferably 150 ° C or higher. When the boiling point is 130 ° C. or lower, the reactive compound may boil and evaporate during the heat treatment of the polyimide film multilayer body, possibly causing separation between polyimide and polyimide.

  As the reactive compound preferably used in the present invention, a silane coupling agent can be used. The silane coupling agents can be used alone or in combination of two or more. Further, it can be used as a solution of alcohol, water and various solvents.

<Silane coupling agent>
The silane coupling agent in the present invention refers to a compound having a silicon element in a molecule, physically and chemically intervening between polyimide films, and having an action of increasing the adhesive force between the two.
Preferred specific examples of the silane coupling agent include N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, N-2- ( (Aminoethyl) -3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N- (1,3-dimethyl-butylidene) propylamine, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, vinyltrichlorosilane, Vinyl trimethoxy silane, vinyl triethoxy sila , 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, p-styryl Trimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, N- (vinylbenzyl) -2-aminoethyl-3-aminopropyltrimethoxysilane hydrochloride, 3-ureidopropyltriethoxysilane, 3-chloropropyl Trimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, bis (triethoxysilylpropyl) tetrasulfide, 3-isocyanatopropyltriethoxysilane, tris- (3-trimethoxysilylpropyl) isocyanurate Chloromethylphenethyltrimethoxysilane, chloromethyltrimethoxysilane, aminophenyltrimethoxysilane, aminophenethyltrimethoxysilane, aminophenylaminomethylphenethyltrimethoxysilane, hexamethyldisilazane and the like.

  Other than the above, silane coupling agents that can be used in the present invention include n-propyltrimethoxysilane, butyltrichlorosilane, 2-cyanoethyltriethoxysilane, cyclohexyltrichlorosilane, decyltrichlorosilane, diacetoxydimethylsilane, and diacetoxydimethylsilane. Ethoxydimethylsilane, dimethoxydimethylsilane, dimethoxydiphenylsilane, dimethoxymethylphenylsilane, dodecyltrichlorosilane, dodecyltrimethoxysilane, ethyltrichlorosilane, hexyltrimethoxysilane, octadecyltriethoxysilane, octadecyltrimethoxysilane, n-octyltrichlorosilane , N-octyltriethoxysilane, n-octyltrimethoxysilane, triethoxyethylsilane, triethoxymethylsilane Trimethoxymethylsilane, trimethoxyphenylsilane, pentyltriethoxysilane, pentyltrichlorosilane, triacetoxymethylsilane, trichlorohexylsilane, trichloromethylsilane, trichlorooctadecylsilane, trichloropropylsilane, trichlorotetradecylsilane, trimethoxypropylsilane, Allyltrichlorosilane, allyltriethoxysilane, allyltrimethoxysilane, diethoxymethylvinylsilane, dimethoxymethylvinylsilane, trichlorovinylsilane, triethoxyvinylsilane, vinyltris (2-methoxyethoxy) silane, trichloro-2-cyanoethylsilane, diethoxy (3- Glycidyloxypropyl) methylsilane, 3-glycidyloxypropyl (dimethoxy) Chirushiran, 3-glycidyloxypropyltrimethoxysilane, and the like may also be used.

  Further, other alkoxysilanes, for example, tetramethoxysilane, tetraethoxysilane, and the like may be appropriately added to the silane coupling agent.

  In addition, if other alkoxylanes such as tetramethoxysilane and tetraethoxysilane are appropriately added to the silane coupling agent, or if they are not added, mixing and heating operations are added to slightly react the reaction. After proceeding, you may use it.

Among such silane coupling agents, the silane coupling agent preferably used in the present invention is preferably a coupling agent having a chemical structure having one silicon atom per molecule.
In the present invention, particularly preferred silane coupling agents include N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, N-2 -(Aminoethyl) -3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N- (1,3-dimethyl-butylidene) propylamine, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, aminophenyl Trimethoxysilane, aminophenethyl trimethoxy Emissions, such as aminophenyl aminomethyl phenethyltrimethoxysilane the like. When particularly high heat resistance is required in the process, it is desirable that Si and the amino group are connected by an aromatic group.
In the present invention, if necessary, a phosphorus-based coupling agent, a titanate-based coupling agent, or the like may be used in combination.

<Method of applying silane coupling agent>
In general, the silane coupling agent treatment refers to a treatment for forming a thin film layer made of a silane coupling agent or a condensate of a silane coupling agent on the surface of an object.
In general, the silane coupling agent treatment is performed by converting the silane coupling agent into a solution of alcohol or the like, not applying the object to the object, applying the object to the silane coupling agent solution by means such as immersion, and then drying and heating the silane coupling agent. By condensing the coupling agent and simultaneously binding it chemically to the surface of the object.
As a method of applying the silane coupling agent, a spin coating method, a spray coating method, a capillary coating method, a dip method, and the like are generally used.
The silane coupling agent treatment is performed on one side or both sides of the polyimide film as necessary.

In the present invention, preferably, the silane coupling agent application step can be performed via a gas phase. Dissolving the gas phase is a method of exposing a polyimide film to a vaporized silane coupling agent. The vaporization refers to the vapor of the silane coupling agent, that is, a state in which the silane coupling agent in a substantially gaseous state or the silane coupling agent in a fine particle state is present. Exposure here means that the polyimide film is brought into contact with an atmosphere containing the vaporized silane coupling agent. Since the silane coupling agent has a certain vapor pressure, a certain amount of the silane coupling agent in a gaseous state exists even at normal temperature. If the silane coupling agent in a liquid state is heated to a temperature from 40 ° C. to the boiling point of the silane coupling agent, a vapor of the silane coupling agent having a higher concentration can be obtained. The vaporized silane coupling agent may be misted due to the dew point and exist in a fine particle state in a gas. The present invention can also utilize such a state. In addition, an operation for increasing the vapor density can be added by operating the temperature and pressure. The boiling point of the silane coupling agent varies depending on the chemical structure, but is generally in the range of 100 to 250 ° C. However, heating at 200 ° C. or higher is not preferable because a side reaction on the organic group side of the silane coupling agent may be caused.
The environment in which the silane coupling agent is heated may be under pressure, under normal pressure, or under reduced pressure. However, in the case of promoting the vaporization of the silane coupling agent, it is preferably under normal pressure or under reduced pressure. Since many silane coupling agents are flammable liquids, it is preferable to perform the vaporizing operation in a closed container, preferably after replacing the inside of the container with an inert gas. However, from the viewpoint of improving production efficiency and reducing the cost of production equipment, it is desirable to apply a silane coupling agent in an environment without using a vacuum. The silane coupling agent deposition method without using a vacuum according to the present invention means that the vacuum is not used only during the deposition, and the polyimide film is usually set in an air atmosphere, and then replaced with a carrier gas to replace the silane coupling agent. Is performed at atmospheric pressure from the time when is deposited until the time when it is returned to the state without the silane coupling agent.
The time for exposing the polyimide film to the silane coupling agent is not particularly limited, but is within 60 minutes, preferably within 20 minutes, and more preferably within 10 minutes. The exposure time is a process design value determined by the relationship between the concentration of the silane coupling agent and the required amount of silane coupling agent applied. Although the lower limit of the exposure time is not particularly limited, it is better to provide a time of about 10 seconds or more, preferably about 30 seconds or more, in order to reduce the unevenness of the coating amount caused industrially.

In the present invention, it is preferable that the polyimide film is exposed to the silane coupling agent vapor while holding the silane coupling agent coated surface of the polyimide film downward. In the conventional method of applying a solution of a silane coupling agent, the application surface of the polyimide film inevitably faces upward during application and before and after application, so that there is a possibility that floating foreign substances and the like in the working environment may deposit on the polyimide film surface. I can't deny it. However, in the present invention, by holding the polyimide film downward, it is possible to greatly reduce the adhesion of foreign substances in the environment.
Further, when introducing a gas containing a vaporized silane coupling agent to a polymer substrate, the gas is once separated and introduced into two or more chambers, and two or more gases collide in the chamber. By doing so, a turbulent flow is generated, and an operation of making the distribution of the silane coupling agent uniform is also effective.
As a method of vaporizing the silane coupling agent, there may be a method of generating a uki (blister) by introducing a gas into the silane coupling agent liquid, in addition to evaporating and vaporizing by heating. This is hereinafter referred to as bubbling. For bubbling, simply put the pipe through which the gas passes into the silane coupling agent solution, attach a porous body at the end of the pipe so that many fine uki (blisters) come out, and superimpose ultrasonic waves. What promotes vaporization is also effective.

  The vaporized silane coupling agent may be sprayed not only on the exposure but also on the polyimide film. In this case, it is desirable that the angle of spraying be 10 ° or more with respect to the film. If the spray angle is 10 ° or less, a sufficient amount of the silane coupling agent may not be applied to the surface of the polyimide film being conveyed.

Further, the vaporized silane coupling agent may be charged. By utilizing this effect, an electric field is applied to the film during exposure, many silane coupling agents can be deposited in a short time, and since the silane coupling agent has kinetic energy, the deposited film becomes an island-like film. Can be suppressed. Further, it is known that, when the carrier gas used contains moisture, the reaction between the moisture and the silane coupling agent starts. Therefore, it is effective that the dew point is low. Desirably, the dew point is 15 ° C. or less, more preferably 10 ° C. or less, and even more preferably 5 ° C. or less.
The number of silicon-containing foreign substances having a major axis of 10 μm or more present in the silane coupling agent layer of the silane coupling agent layer-laminated polyimide film is 2,000 / m ² or less, preferably 1,000 / m ² or less, and more preferably 500 / m ² or less. Is a preferred embodiment of the present invention. Also, the number of silicon-containing foreign substances can be achieved by combining the above operations.

The amount of the silane coupling agent applied depends on the thickness of the silane coupling agent condensate layer. If the coupling agent layer is too thick, the amount of decomposition products generated at the time of high-temperature exposure increases, which may hinder the adhesion between the polyimide films. The thickness of the silane coupling agent condensate layer of the invention is preferably from 0.1 nm to 800 nm, more preferably from 0.5 nm to 200 nm. Further, the upper limit of the thickness is preferably less than 200 nm, preferably 150 nm or less, more preferably 100 nm or less, more preferably 70 nm or less, further preferably 50 nm or less. In the region of 0.1 nm or less, a case where the coupling agent exists not in a uniform coating film but in a cluster shape is assumed, which is not preferable.
The thickness of the silane coupling agent condensate layer was determined by polishing the cross section in the direction perpendicular to the film surface of the polyimide film laminate, forming an ultrathin section with a microtome, taking a cross-sectional photograph with a transmission electron microscope, and measuring the measured value. It was obtained by calculating backward from the magnification.

<Film lamination conditions>
In the present invention, a polyimide film is obtained by laminating a polyimide film layer and a silane coupling agent condensate layer alternately by laminating a polyimide film via a silane coupling agent layer.
The lamination of the polyimide films is performed by stacking and pressing the polyimide films so that the surface subjected to the silane coupling agent treatment is disposed between the polyimide film layers. Combination of pressurization and heating is effective.
The pressure treatment may be performed, for example, while heating, such as press, lamination, and roll lamination, in an atmosphere of atmospheric pressure or in a vacuum. A method of heating under pressure in a flexible bag can also be applied. From the viewpoint of improving productivity and reducing processing costs brought about by high productivity, press or roll lamination in an air atmosphere is preferable, and a method using a roll (roll lamination or the like) is particularly preferable.

The pressure at the time of the pressure treatment is preferably from 1 MPa to 30 MPa, more preferably from 3 MPa to 25 MPa. If the pressure is too high, there is a possibility that the polyimide film layered body may be damaged. If the pressure is too low, a portion that does not adhere may be formed, and the adhesion may be insufficient. Although the pressure treatment can be performed in the atmospheric pressure atmosphere as described above, it is preferable to perform the pressure treatment in a vacuum in order to obtain a stable adhesive strength over the entire surface. At this time, the degree of vacuum by a normal oil rotary pump is sufficient, and about 10 Torr or less is sufficient.
As a device that can be used for the pressurized heat treatment, for example, "11FD" manufactured by Imoto Seisakusho can be used to perform pressing in a vacuum, and a roll-type film laminator in a vacuum or a vacuum is used. For performing vacuum lamination of a film laminator or the like in which pressure is applied to the entire surface of the glass at once with a thin rubber film, "MVLP" manufactured by Meiki Seisakusho can be used.

  The storage environment in a state before the heat treatment of the single-layer polyimide film or the polyimide film multilayer body after the application of the reactive compound in the present invention is preferably 15 ° C. or lower, more preferably 5 ° C. or lower, still more preferably. Is −5 ° C. or lower, more preferably −15 ° C. or lower.

The method used for heat treatment of the polyimide film multilayer body in the present invention is not particularly limited. For example, a batch oven, a superheated steam furnace, a hot plate, a roll-to-roll heating furnace, or the like can be used. Further, the processing atmosphere may be either air or inert gas atmosphere.

The heat treatment temperature of the polyimide film multilayer body in the present invention is preferably 70 ° C. or higher, more preferably 100 ° C. or higher, and further preferably 150 ° C. or higher. If the processing temperature is lower than 70 ° C., the reaction between the films may be insufficient or a long-time processing may be required.

  The water content per polyimide film multilayer body in the present invention is desirably 1.5% by mass or less. The polyimide film multilayer body before heating is weakly adhered via the reactive compound layer. Therefore, when the water content is 1.5% by mass or more, there is a possibility that uki (blister) may be generated between the films due to moisture evaporated during heating for bonding between the polyimides.

  The process from the application of the reactive compound to the polyimide film to the heat treatment in the present invention may be any of a batch system, a roll-to-roll system, or a combination thereof.

  The adhesive strength between the polyimide layers of the polyimide film multilayer body in the present invention is 2 N / cm or less, preferably 1.5 N / cm or less in a 90-degree peeling method. When the adhesive strength is higher than 2 N / cm, the adhesive strength between the polyimide layers is sufficiently strong, so that a high-quality polyimide film laminate can be obtained after heat treatment regardless of the amount of moisture contained in the polyimide film.

The adhesive strength between the polyimide film layers of the polyimide film laminate of the present invention after the heat treatment is 0.4 N / cm or more and 20 N / cm or less, preferably 0.4 N / cm or more and 18 N / cm, more preferably 0.4 N / cm or more and 15 N / cm or less.

    Hereinafter, the present invention will be described more specifically with reference to Examples, but the present invention is not limited to the following Examples. The methods for evaluating physical properties in the following examples are as follows.

<Number of uki (blister)>
The number of uki (blisters) having a diameter of 0.1 mm or more and 5 mm or less and having no nuclei serving as nuclei in a 10 cm × 10 cm laminate was counted. The number of uki (blisters) was measured so that n = 5 for each sample, and the decimals were rounded off. For example, in the case of a three-layer laminate, a value obtained by dividing the actual number by two was used so that the number of blisters (blisters) would be a value equivalent to a two-layer laminate. That is, it was normalized by the number of reactive compound layers sandwiched between the polyimide film layers. According to another expression, it has the same meaning as standardized by ((the number of polyimide film layers −1)).
In order to count only the uki (blisters) generated during the heat treatment, the uki (blisters) that existed before the heat treatment were marked and excluded from the count of the uki (blisters) generated during the heat treatment.

<Delamination strength>
The adhesive strength between the polyimide film layers of the polyimide film laminate was determined according to the 90-degree peeling method of JIS K 6854-1.
Equipment name: Autograph AG-IS manufactured by Shimadzu Corporation
Measurement temperature: room temperature Peeling speed: 50 mm / min
Atmosphere: Atmosphere Measurement sample width: 1cm
The sample was cut into the surface of a square polyimide film laminate having a side of 100 mm to a depth corresponding to 120% of the thickness of the outermost polyimide film, and the outermost polyimide film was peeled off from the end of the laminate and measured. .
The adhesive strength was measured after the heat treatment.

<Water content of polyimide film (TGA)>
The measurement was performed using a thermogravimeter (TGA-50) manufactured by Shimadzu Corporation in a nitrogen atmosphere at a rate of temperature increase of 5 ° C./min. The samples used were polyimide films which were conditioned overnight in a constant temperature and humidity chamber maintained at 27 ° C. 4% RH (under a nitrogen atmosphere), 23 ° C. 50% RH, and 35 ° C. 95% RH.
(Production example)
(Preparation of polyamic acid solution)
After the inside of a reaction vessel equipped with a nitrogen introduction tube, a thermometer, and a stirring bar was replaced with nitrogen, 223 parts by mass of 5-amino-2- (p-aminophenyl) benzoxazole (DAMBO) and 4416 parts of N, N-dimethylacetamide were added. Parts by weight and completely dissolved. Then, together with 217 parts by weight of pyromellitic dianhydride (PMDA), a dispersion obtained by dispersing colloidal silica as a lubricant in dimethylacetamide (“Snowtex (manufactured by Nissan Chemical Industries, Ltd.) (Registered trademark) DMAC-ST30 ”) so that the silica (lubricant) becomes 0.12% by mass based on the total polymer solid content in the polyamic acid solution, and stirred at a reaction temperature of 25 ° C. for 24 hours. A brown and viscous polyamic acid solution V1 was obtained.

(Preparation of polyamic acid solution)
After replacing the inside of the reaction vessel equipped with a nitrogen introduction tube, a thermometer and a stirring bar with nitrogen, 205.8 g of 1,4-bis (4-amino-2-trifluoromethylphenoxy) benzene (205.8 g) was added to the reaction vessel under a nitrogen atmosphere. 0.480 mol) and 1200 g of N, N-dimethylacetamide were charged and dissolved, and 93.8 g (0.478 mol) of cyclobutanetetracarboxylic dianhydride was added in a solid state while cooling the reaction vessel, and the mixture was added at room temperature. For 12 hours. Thereafter, 1.0 g (5.9 mmol) of 4-methylcyclohexane-1,2-dicarboxylic anhydride was added, and the mixture was stirred for 4 hours. The mixture was diluted with 1000 g of N, N-dimethylacetamide to obtain a polyamide having a reduced viscosity of 5.28 dl / g. An acid solution V2 was obtained. A solution obtained by dispersing colloidal silica fine particles having an average particle size of 0.08 μm in N, N-dimethylacetamide in a polyamic acid solution V2 having an amine terminal amount of 5 eq / t was used. It was added so as to be 0% by mass to obtain a fine particle-containing polyamic acid solution V2 ′.

(Preparation of polyimide film)
Using a slit die, the polyamic acid solution V1 obtained above was coated on a smooth surface (non-lubricated surface) of a long polyester film (“A-4100” manufactured by Toyobo Co., Ltd.) with a width of 1050 mm to obtain a final film thickness (imide). (Polymerized film thickness) was 38 μm, dried at 105 ° C. for 20 minutes, and peeled from the polyester film to obtain a self-supporting polyamic acid film having a width of 920 mm.
After the polyamic acid film obtained above is obtained, it is subjected to a heat treatment by a pin tenter (first stage 150 ° C. × 5 minutes, second stage 220 ° C. × 5 minutes, third stage 495 ° C. × 10 minutes) and imidized. Then, the pin holding portions at both ends were dropped by slits to obtain a long polyimide film F1 (1000 m winding) having a width of 850 mm.

(Preparation of polyimide film)
A polyamic acid solution V2 ′ containing fine particles is applied to a 188 μm-thick polyester film using a comma coater so as to have a final dry thickness of 3 μm, and then a polyamic acid solution V2 is coated thereon with a T-die so as to have a final dry thickness of 40 μm. A thin film extruded continuously from the slit was formed. Each of the polymer solutions was supplied through a defoaming step and a filtration step of passing through a polymer filter having a filtration accuracy of 3 μm. After heating this thin film at 110 ° C. to 135 ° C. for 15 minutes, it was separated from the support to obtain a self-supporting film having a volatile component of 23.7% by mass.

Subsequently, the self-supporting film was gripped at both ends by a film gripping device attached to a chain driven along a rail, and inserted into a continuous heating furnace heated to 150 ° C to 320 ° C. The heat treatment was performed under the condition that the treatment was performed for 5 minutes or less. The oxygen concentration in the furnace at that time was 20.6%. The imidization was completed when the volatile component amount was 1% by mass or less by the above process, thereby obtaining a long polyimide film F3 (200 m winding) having a thickness of 40 µm.

<Vacuum plasma treatment of polyimide film>
As a pre-process of performing a silane coupling agent treatment or a diamine treatment on the polyimide film, a vacuum plasma treatment was performed on the polyimide film. Vacuum plasma processing is performed using a device for sheet glass or a device for processing long film, and the inside of the vacuum chamber is evacuated to a pressure of 1 × 10 −3 Pa or less, and argon gas is introduced into the vacuum chamber and discharged. Plasma treatment with argon gas was performed for 20 seconds at a power of 100 W and a frequency of 15 kHz. Hereinafter, in Examples and Comparative Examples, a wide polyimide film after plasma treatment was slit or a film cut in advance to a sample size was used after plasma treatment.

<Silane coupling agent treatment 1>
The silane coupling agent was applied to the polyimide film under the following conditions using an apparatus for generating a silane coupling agent vapor schematically shown in FIG.
A 220 mm wide polyimide film was passed through a 750 mm × 20 mm × 10 mm chamber having a slit of 20 mm × 250 mm at a speed of 240 mm / min.
After adjusting the temperature of the container containing 100 g of the silane coupling agent to 40 ° C., nitrogen gas is sent at a rate of 10 L / min in a bubbling manner, and the nitrogen gas containing the generated silane coupling agent vapor is passed through the pipe into the first chamber. Then, both surfaces of the polyimide film were exposed to the gas for 3 minutes, and then immediately laminated with the second and third polyimide films at a pressure of 2 MPa to obtain a polyimide film multilayer body.

<Silane coupling agent treatment 2>
The silane coupling agent treatment was performed on the polyimide film under the following conditions using an apparatus for generating a silane coupling agent vapor schematically shown in FIG. Holding the polyimide film in a stainless steel frame having an opening of 370 mm × 470 mm,
The silane coupling agent was held vertically in the chamber for introducing the vapor. After the temperature of the container containing 100 g of the silane coupling agent is adjusted to 40 ° C., nitrogen gas is sent at a flow rate of 10 L / min in a bubbling manner, and the generated nitrogen gas containing the silane coupling agent vapor is passed through the pipe into the chamber. And both sides of the polyimide film were exposed to the gas for 5 minutes. Thereafter, the film was taken out of the chamber and heated in a clean dry oven at 110 ° C. for 1 minute to perform a silane coupling agent treatment.

<Laminate>
A plurality of reactive compound-coated polyimide films obtained by the silane coupling agent treatment 2 method are stacked to form a multilayer body, and further, a release sheet is sandwiched, and a pressure of 100 Pa is applied under reduced pressure by a vacuum press to perform temporary bonding. went. Next, the obtained temporary adhesive laminate was placed in a clean oven and heated at a predetermined temperature under a nitrogen atmosphere for 1 hour to obtain a polyimide film laminate. Table 1 shows the evaluation results of the obtained polyimide film laminates.

The reactive compounds and polyimide films used in Comparative Examples and Examples are summarized below.
<Reactive compound>
SC1: KBM-903 (Shin-Etsu Chemical Co., Ltd., 3-aminopropyltrimethoxysilane)
SC2: KBM-603 (Shin-Etsu Chemical Co., Ltd., N-2- (aminoethyl) -3-aminopropyltrimethoxysilane)
SC3: KBM-1003 (Shin-Etsu Chemical Co., Ltd., vinyltrimethoxysilane)
<Commercially available polyimide film>
F2: Kapton 100EN (Toray Dupont Co., Ltd. polyimide film, thickness 25 μm)

<Comparative Example 1>
Three polyimide films F1 were overlaid via SC1 by silane coupling agent treatment 1, and temporary bonding was performed. Next, the obtained polyimide film multilayer body was cut into a 10 cm square, placed in a clean oven, and heated at 200 ° C. for 1 hour under a nitrogen atmosphere to obtain a polyimide film laminate. Table 1 shows the evaluation results of the obtained polyimide film laminates.

<Comparative Example 2>
Six polyimide films F1 coated with SC3 obtained by the silane coupling agent treatment 2 are overlapped, a release sheet is sandwiched, and a pressure of 100 Pa is applied to reduce the pressure by a vacuum press to perform temporary bonding. Was. Next, the obtained polyimide film multilayer body was placed in a clean oven and heated at 200 ° C. for 1 hour in a nitrogen atmosphere to obtain a polyimide film laminate. Table 1 shows the evaluation results of the obtained polyimide film laminates.

<Comparative Example 3>
It carried out similarly to the comparative example 2 except having used the film from which a water content differs. Table 1 shows the evaluation results of the obtained polyimide film laminates.

<Example 1>
Six polyimide films F1 coated with SC1 obtained by the silane coupling agent treatment 2 were stacked, and subjected to pressure and heat treatment in the same manner as in Comparative Example 2 to obtain a polyimide film laminate. Table 1 shows the evaluation results of the obtained polyimide film laminates.

<Example 2>
A polyimide film laminate was obtained in the same manner as in Comparative Example 2 except that a heat treatment temperature was set to 150 ° C. using a film having a different water content, SC1. Table 1 shows the evaluation results of the obtained polyimide film laminates.

<Example 3>
A polyimide film laminate was obtained in the same manner as in Comparative Example 1 except that films having different water contents were used. Table 1 shows the evaluation results of the obtained polyimide film laminates.

<Example 4>
A polyimide film laminate was obtained by applying pressure and heat as in Comparative Example 2, except that F2 was used as the film and SC2 was used as the silane coupling agent. Table 1 shows the evaluation results of the obtained polyimide film laminates.

<Example 5>
Using F3 as the film and SC1 as the silane coupling agent, a silane coupling agent was applied, pressurized and heat-treated in the same manner as in the example to obtain a polyimide film laminate.

  As described above, the polyimide film laminate of the present invention is a high-quality polyimide film laminate in which the number of uki (blisters) between polyimide film layers is suppressed. The present invention relates to a case where a film laminate is produced using various reactive compounds such as an epoxy resin which is a thermosetting compound, a (meth) acrylate which is a photocurable compound, and a silane coupling agent as exemplified above. In addition to being effectively used as a stiffener for a flexible printed wiring board, it can be used in various industrial fields as a thick polyimide sheet or plate.

DESCRIPTION OF SYMBOLS 11 Base film 12 Adhesive layer 13 Separator 14 Flexible printed circuit board 22 Adhesive layer 23 Copper foil 31 Polyimide film 32 Adhesive layer 51 Film unwinding part 52 Coating liquid supply part 53 Coating liquid discharge part 54 Coating liquid vapor Exhaust port 55 second elongate base material unwinding part 56 pressurizing part 57 winding part 58 height adjustment roll 59 of elongate base material 59 third elongate base material unwinding part

Claims (5)

  Number of uki (blisters) having a diameter of 100 μm or more and 5 mm or less, which is a polyimide film laminate having a structure in which a plurality of polyimide film layers and reactive compound layers are alternately stacked, and does not have a foreign substance core existing between the polyimide film layers Is not more than ((number of polyimide film layers −1) × 5) per 100 square cm.   The polyimide film laminate according to claim 1, wherein the thickness of the reactive compound layer is 5 nm or more and 800 nm or less. In the method for producing a polyimide film laminate obtained by heat-treating a polyimide film laminate having a structure in which a plurality of polyimide film layers and reactive compound layers are alternately stacked, an average amount of moisture contained in the polyimide film layer A heat treatment at 180 ° C. or less when the content is 1.5% by mass or more, and at 180 ° C. or more when the content is less than 1.5% by mass.   The heat treatment is performed after alternately stacking the polyimide film layers and the reactive compound layers such that the peel strength between the respective polyimide film layers in the polyimide film multilayer body before the heat treatment is 2 N / cm or less. 3. The method for producing a polyimide film laminate according to item 1. 5. The method for producing a polyimide film laminate according to claim 3, wherein the reactive compound forming the reactive compound layer is liquid at 40 ° C. and has a boiling point of 100 ° C. or higher.