JP2010076438A - Slippery multilayer polyimide film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multilayer film having high physical properties and sufficient slipperiness. <P>SOLUTION: The multilayer polyimide film is produced by piling up: a layer comprising as a main component, polyimide obtained by making aromatic tetracarboxylic acids react with aromatic diamines and containing inorganic fine particles of 0.5 to 50 mass%; and another layer comprising the same as above, but containing the inorganic fine particles of 0.1 mass% or lower. The tensile moduli of the multilayer film in the longitudinal and width directions are both 6.0 GPa or higher. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a slippery and easy-to-slip multilayer polyimide film that contains a lubricant such as fine particles in a small addition amount with respect to the entire film, and hardly deteriorates the original physical properties of the film. The present invention relates to a copper-clad laminate and a circuit board using a polyimide film having both slipperiness and high physical properties by forming a specific form.

  Polyimide films are excellent in heat resistance, chemical resistance, mechanical strength, electrical properties, etc., so flexible printed wiring boards, TAB tape substrates, chip-on-film substrates, magnetic recording medium substrates, etc. Are widely used in the field of electronic information. In general, in the production of a polymer film, slipperiness is imparted to the film by providing fine protrusions on the film surface. More specifically, when the films overlap each other or when the film and a smooth surface overlap each other, the film is easily slipped due to air being appropriately wound into the overlapped portion due to fine protrusions on the film surface. If the film does not exhibit sufficient slipperiness, wrinkles are likely to occur when the film is wound into a roll shape, and meandering is likely to occur when transporting a long film, making it extremely difficult to handle the film. become.

  As a known means for forming fine protrusions on the surface of the film, there is a means for containing a minute amount of inorganic or organic fine particles called a lubricant in the film. As a result, the lubricant present in the vicinity of the surface of the film becomes fine protrusions on the surface of the film and can exhibit the above-mentioned slipperiness. For example, by mixing fine particles made of an inorganic compound such as calcium phosphate as a filler in a polyimide film and generating fine protrusions on the film surface (see Patent Document 1), from inorganic compounds such as silica A method of mixing fine particles to form fine protrusions on the film surface and reducing surface friction (see Patent Document 2) has been employed. Also known is a method of producing a polyimide film by casting a polyamic acid solution in which fine inorganic fine particles are dispersed and polymerized in a solvent (see Patent Document 3). Specifically, after dispersing inorganic fine particles in an organic solvent in advance, a polyamic acid solution is prepared by adding an aromatic tetracarboxylic dianhydride and an aromatic diamine to this filler-dispersed organic polar solvent and reacting them. However, a method for producing a slippery polyimide film by forming a film of this polyamic acid solution and then imidating with heating has been adopted.

JP-A 62-068852 JP-A-62-068853 Japanese Patent Laid-Open No. 06-145378

In the polyamic acid solution, inorganic fine particles having a particle size distribution in which the median average diameter is 0.8 to 1.0 μm and the ratio of the particle diameter of 5 μm or more is 2% or less is 5 to 30% by weight. The low-viscosity inorganic fine particle-containing solution uniformly dispersed in is mixed with a polyamic acid solution that does not contain inorganic fine particles, and after forming this polyamic acid solution, the static friction coefficient between the film surfaces is 0.1 to 10. 1.2 A slippery polyimide film (see Patent Document 4), having a polyimide surface layer made of thermoplastic polyimide, at least 80% of pyromellitic acid component and p-phenylenediamine component in about 1 μm of polyimide surface layer Polyaromatic polyimide particles having a median diameter of 0.3 to 0.8 [mu] m and a maximum diameter of 2 [mu] m or less made of a polyimide containing polyimide Also known is a polyimide film with improved slipperiness (see Patent Document 5) which is dispersed at a ratio of about 0.5 to 10% by mass with respect to the imide.
JP 2002-256085 A JP, 2005-126707, A Such a sliding material is very important in order to make a polyimide film easy to handle. However, the polyimide film containing the lubricant as described above is known that the lubricant itself acts as a foreign substance in the film and causes the film to be torn, and the mechanical strength, elongation, and elastic modulus are affected. The adverse effect is great.

  The prescription for lubricants in conventional polyimide films gives slipperiness to the film, but has not yet reached a level that can completely eliminate the adverse effects on the inherent properties of the film, especially in high modulus films. At present, a sufficient lubricant additive formulation has not been found. An object of the present invention is to provide a multilayer film that can impart sufficient slipperiness without impairing the inherent properties of the film.

That is, this invention is based on the following structure.
1. A multilayer polyimide film characterized in that at least the following layers (a) and (b) are laminated, and the tensile modulus in the longitudinal direction and the tensile modulus in the width direction are both 6.0 GPa or more.
(A) Layer: polyimide obtained by reacting aromatic tetracarboxylic acids and aromatic diamines, containing 0.5% to 50% by mass of inorganic fine particles having an average particle size of 0.05 to 2.5 μm A layer mainly composed of
(B) Layer: A polyimide obtained by reacting aromatic tetracarboxylic acids and aromatic diamines, wherein the content of inorganic fine particles having an average particle size of 0.05 to 2.5 μm is 0.1% by mass or less. The main component layer.
2. 1. The structure of the multilayer polyimide film is a three-layer structure of (a) layer- (b) layer- (a) layer. Multilayer polyimide film.
3. (A) Layer to (b) layer thickness ratio: (a) / (b) is 0.005 to 0.5, and (a) layer thickness is 0.01 μm to 5 μm, (b ) Layer thickness is 1 μm to 50 μm ~ 2. Any multilayer polyimide film.
4). Polyimide is a polyimide having at least pyromellitic acid as a residue of aromatic tetracarboxylic acids and a benzoxazole structure as a residue of aromatic diamines, and has a linear expansion coefficient in the plane direction of −10 ppm / ° C. to 10 ppm / 1 ° C. ~ 3. Any multilayer polyimide film.

  Layer (a) of the present invention: an aromatic tetracarboxylic acid and an aromatic diamine containing 0.5 to 50% by mass of inorganic fine particles having an average particle size of 0.05 to 2.5 μm are reacted. A layer containing polyimide as a main component and layer (b): aromatic tetracarboxylic acids and aromatics having a content of inorganic fine particles having an average particle size of 0.05 to 2.5 μm of 0.1% by mass or less A multilayer polyimide film in which the tensile modulus in the longitudinal direction and the tensile modulus in the width direction, which are obtained by laminating a layer mainly composed of polyimide obtained by reacting with a group diamine, are 6.0 GPa or more are fine particles, etc. The lubricant is contained in a small amount with respect to the whole film, so that the original physical properties of the film are hardly deteriorated, and it becomes a slippery and easy-sliding multilayer polyimide film. This is effective for insulating substrates such as copper-clad laminates and circuit boards, and is extremely significant industrially.

The present invention is described in detail below.
In the present invention, polyimide obtained by reacting aromatic tetracarboxylic acids and aromatic diamines, for example, aromatic tetracarboxylic acids (collectively referred to as anhydrides, acids, and amide-bonded derivatives) And a polyamic acid solution obtained by reacting aromatic diamines (generically referred to as amines and amide bond derivatives, hereinafter the same) and molding, followed by imidization, For example, in the case of forming a film as a layer, it can be obtained by a method of forming a film by casting, drying and heat treatment (imidization).
Although the said polyimide (film) is not specifically limited, The combination of the following aromatic diamine and aromatic tetracarboxylic acid (anhydride) is mentioned as a preferable example.
A. Combination with aromatic tetracarboxylic acid having pyromellitic acid residue and aromatic diamine having benzoxazole structure.
B. A combination of an aromatic diamine having a phenylenediamine skeleton and an aromatic tetracarboxylic acid having a biphenyltetracarboxylic acid skeleton.
C. A combination of an aromatic diamine having a diphenyl ether skeleton and an aromatic tetracarboxylic acid having a pyromellitic acid residue.
In particular, A. A polyimide film having an aromatic diamine residue having a benzoxazole structure is preferred.

  The molecular structure of the aromatic diamines having the benzoxazole structure is not particularly limited, and specific examples include the following. These diamines are preferably 70 mol% or more, more preferably 80 mol% or more of the total diamine.

  Among these, from the viewpoint of easy synthesis, each isomer of amino (aminophenyl) benzoxazole is preferable, and 5-amino-2- (p-aminophenyl) benzoxazole is more preferable. Here, “each isomer” refers to each isomer in which two amino groups of amino (aminophenyl) benzoxazole are determined according to the coordination position (eg, the above “formula 1” to “formula 4”). Each compound described in the above. These diamines may be used alone or in combination of two or more.

  Furthermore, as long as it is 30 mol% or less of the total diamine, one or more of the diamines exemplified below may be used in combination. Examples of such diamines include 4,4′-bis (3-aminophenoxy) biphenyl, bis [4- (3-aminophenoxy) phenyl] ketone, and bis [4- (3-aminophenoxy) phenyl]. Sulfide, bis [4- (3-aminophenoxy) phenyl] sulfone, 2,2-bis [4- (3-aminophenoxy) phenyl] propane, 2,2-bis [4- (3-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, m-phenylenediamine, o-phenylenediamine, p-phenylenediamine, m-aminobenzylamine, p-aminobenzylamine, 3,3′-diamino Diphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 3,3'-dia Nodiphenyl sulfide, 3,3′-diaminodiphenyl sulfoxide, 3,4′-diaminodiphenyl sulfoxide, 4,4′-diaminodiphenyl sulfoxide, 3,3′-diaminodiphenyl sulfone, 3,4′-diaminodiphenyl sulfone, 4 , 4′-diaminodiphenylsulfone, 3,3′-diaminobenzophenone, 3,4′-diaminobenzophenone, 4,4′-diaminobenzophenone, 3,3′-diaminodiphenylmethane, 3,4′-diaminodiphenylmethane, 4, 4′-diaminodiphenylmethane, bis [4- (4-aminophenoxy) phenyl] methane, 1,1-bis [4- (4-aminophenoxy) phenyl] ethane, 1,2-bis [4- (4-amino) Phenoxy) 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, , 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-a Minophenoxy) -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-hexa Fluoropropane, 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-amino) Enoxy) phenyl] sulfoxide, bis [4- (4-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] ether, bis [4- (4-aminophenoxy) phenyl] ether, 1, 3-bis [4- (4-aminophenoxy) benzoyl] benzene, 1,3-bis [4- (3-aminophenoxy) benzoyl] benzene, 1,4-bis [4- (3-aminophenoxy) benzoyl] Benzene, 4,4′-bis [(3-aminophenoxy) benzoyl] benzene, 1,1-bis [4- (3-aminophenoxy) phenyl] propane, 1,3-bis [4- (3-aminophenoxy) ) Phenyl] propane, 3,4'-diaminodiphenyl sulfide, 2,2-bis [3- (3-aminophenoxy) phenyl -1,1,1,3,3,3-hexafluoropropane, bis [4- (3-aminophenoxy) phenyl] methane, 1,1-bis [4- (3-aminophenoxy) phenyl] ethane, 1 , 2-bis [4- (3-aminophenoxy) phenyl] ethane, bis [4- (3-aminophenoxy) phenyl] sulfoxide, 4,4′-bis [3- (4-aminophenoxy) benzoyl] diphenyl ether, 4,4′-bis [3- (3-aminophenoxy) benzoyl] diphenyl ether, 4,4′-bis [4- (4-amino-α, α-dimethylbenzyl) phenoxy] benzophenone, 4,4′-bis [4- (4-Amino-α, α-dimethylbenzyl) phenoxy] diphenylsulfone, bis [4- {4- (4-aminophenoxy) phenoxy} fe Sulfone, 1,4-bis [4- (4-aminophenoxy) phenoxy-α, α-dimethylbenzyl] benzene, 1,3-bis [4- (4-aminophenoxy) phenoxy-α, α-dimethyl Benzyl] benzene, 1,3-bis [4- (4-amino-6-trifluoromethylphenoxy) -α, α-dimethylbenzyl] benzene, 1,3-bis [4- (4-amino-6-fluoro) Phenoxy) -α, α-dimethylbenzyl] benzene, 1,3-bis [4- (4-amino-6-methylphenoxy) -α, α-dimethylbenzyl] benzene, 1,3-bis [4- (4 -Amino-6-cyanophenoxy) -α, α-dimethylbenzyl] benzene, 3,3′-diamino-4,4′-diphenoxybenzophenone, 4,4′-diamino-5,5′-dipheno Cibenzophenone, 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-biphenoxybenzoyl) benzene, 1,4-bis (3-amino-4-bi) Phenoxybenzoyl) 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 some or all of the hydrogen atoms on the aromatic ring of the aromatic diamine are halogen atoms, An alkyl group having 1 to 3 carbon atoms, an alkoxyl group, a cyano group, or an alkyl group or an alkoxyl group having 1 to 3 carbon atoms in which some or all of the hydrogen atoms of the alkyl group or alkoxyl group are substituted with halogen atoms. Examples thereof include substituted aromatic diamines.

  The molecular structure of the aromatic tetracarboxylic acid anhydrides is not particularly limited, and specific examples include the following. These acid anhydrides are preferably 70 mol% or more, more preferably 80 mol% or more of the total acid anhydride.

  These tetracarboxylic dianhydrides may be used alone or in combination of two or more.

  Furthermore, as long as it is 30 mol% or less of the total tetracarboxylic dianhydrides, one or more of the non-aromatic tetracarboxylic dianhydrides exemplified below may be used in combination. Examples of such tetracarboxylic acid anhydrides include butane-1,2,3,4-tetracarboxylic dianhydride, pentane-1,2,4,5-tetracarboxylic dianhydride, and cyclobutanetetracarboxylic acid. Acid dianhydride, cyclopentane-1,2,3,4-tetracarboxylic dianhydride, cyclohexane-1,2,4,5-tetracarboxylic dianhydride, cyclohex-1-ene-2,3 5,6-tetracarboxylic dianhydride, 3-ethylcyclohex-1-ene-3- (1,2), 5,6-tetracarboxylic dianhydride, 1-methyl-3-ethylcyclohexane-3 -(1,2), 5,6-tetracarboxylic dianhydride, 1-methyl-3-ethylcyclohex-1-ene-3- (1,2), 5,6-tetracarboxylic dianhydride 1-ethylcyclohexane -(1,2), 3,4-tetracarboxylic dianhydride, 1-propylcyclohexane-1- (2,3), 3,4-tetracarboxylic dianhydride, 1,3-dipropylcyclohexane- 1- (2,3), 3- (2,3) -tetracarboxylic dianhydride, dicyclohexyl-3,4,3 ′, 4′-tetracarboxylic dianhydride, bicyclo [2.2.1] Heptane-2,3,5,6-tetracarboxylic dianhydride, 1-propylcyclohexane-1- (2,3), 3,4-tetracarboxylic dianhydride, 1,3-dipropylcyclohexane-1 -(2,3), 3- (2,3) -tetracarboxylic dianhydride, dicyclohexyl-3,4,3 ', 4'-tetracarboxylic dianhydride, bicyclo [2.2.1] heptane -2,3,5,6-tetracarboxylic dianhydride, Cyclo [2.2.2] octane-2,3,5,6-tetracarboxylic dianhydride, bicyclo [2.2.2] oct-7-ene-2,3,5,6-tetracarboxylic acid A dianhydride etc. are mentioned.

  The solvent used when reacting (polymerizing) the aromatic tetracarboxylic acid and the aromatic diamine to obtain a polyamic acid is particularly suitable as long as it can dissolve both the raw material monomer and the produced polyamic acid. Although not limited, polar organic solvents are preferred, such as N-methyl-2-pyrrolidone, N-acetyl-2-pyrrolidone, N, N-dimethylformamide, N, N-diethylformamide, N, N-dimethylacetamide, dimethyl Examples thereof include sulfoxide, hexamethylphosphoric amide, ethyl cellosolve acetate, diethylene glycol dimethyl ether, sulfolane, and halogenated phenols. These solvents can be used alone or in combination. The amount of the solvent used may be an amount sufficient to dissolve the monomer as a raw material. As a specific amount used, the weight of the monomer in the solution in which the monomer is dissolved is usually 5 to 40% by weight, The amount is preferably 10 to 30% by weight.

  Conventionally known conditions may be applied for the polymerization reaction for obtaining the polyamic acid (hereinafter also simply referred to as “polymerization reaction”). As a specific example, in a temperature range of 0 to 80 ° C., 10 Stirring and / or mixing continuously for minutes to 30 hours. If necessary, the polymerization reaction may be divided or the temperature may be increased or decreased. In this case, the order of adding both monomers is not particularly limited, but it is preferable to add aromatic tetracarboxylic acid anhydrides to the solution of aromatic diamines. The viscosity of the polyamic acid solution obtained by the polymerization reaction is measured with a Brookfield viscometer (25 ° C.), and is preferably 10 to 2000 Pa · s, more preferably 100 to 1000 Pa · s, from the viewpoint of the stability of liquid feeding. It is.

Vacuum degassing during the polymerization reaction is effective in producing a good quality polyamic acid solution. Moreover, you may perform superposition | polymerization by adding a small amount of terminal blockers to aromatic diamines before a polymerization reaction. Examples of the end capping agent include compounds having a carbon-carbon double bond such as maleic anhydride. The amount of maleic anhydride used is preferably 0.001 to 1.0 mole per mole of aromatic diamine.
In order to form a polyimide film, which is one of the layers of the present invention, from a polyamic acid solution obtained by a polymerization reaction, the polyamic acid solution is applied onto a support and dried to form a green film (self-supporting precursor). There is a method in which a body film is obtained, and then an imidization reaction is performed by subjecting the green film to heat treatment, such as application of a polyamic acid solution to a support, casting from a slit-attached die, extrusion by an extruder, etc. However, it is not restricted to these, The conventionally well-known application | coating means of a solution can be used suitably.

  The conditions for drying the polyamic acid coated on the support to obtain a green sheet are not particularly limited, and examples include a temperature of 70 to 150 ° C. and a drying time of 5 to 180 minutes. A conventionally known drying apparatus that satisfies such conditions can be applied, and examples thereof include hot air, hot nitrogen, far infrared rays, and high frequency induction heating. Next, in order to obtain a target polyimide film from the obtained green sheet, an imidization reaction is performed. As a specific method thereof, a conventionally known imidation reaction can be appropriately used. For example, there may be mentioned a method (so-called thermal ring closure method) in which an imidization reaction proceeds by subjecting it to a heat treatment after performing a stretching treatment as necessary using a polyamic acid solution containing no ring closure catalyst or a dehydrating agent. The heating temperature in this case is exemplified by 100 to 500 ° C. From the viewpoint of film physical properties, more preferably, a two-stage heat treatment in which the treatment is performed at 150 to 250 ° C. for 3 to 20 minutes and then treatment at 350 to 500 ° C. for 3 to 20 minutes. Is mentioned.

Another example of the imidization reaction is a chemical ring closure method in which a polyamic acid solution contains a ring closure catalyst and a dehydrating agent, and the imidization reaction is performed by the action of the ring closing catalyst and the dehydrating agent. In this method, after the polyamic acid solution is applied to the support, the imidization reaction is partially advanced to form a film having self-supporting property, and then imidization can be performed completely by heating. In this case, the condition for partially proceeding with the imidization reaction is preferably a heat treatment for 3 to 20 minutes at 100 to 200 ° C., and the condition for allowing the imidization reaction to be completely performed is preferably 200 to 400 ° C. For 3 to 20 minutes.

The multilayer polyimide film of the present invention preferably has a linear expansion coefficient in the plane direction of −10 ppm / ° C. to 20 ppm / ° C., more preferably −10 ppm / ° C. to 15 ppm / ° C., and still more preferably −10 ppm / ° C. 10 ppm / ° C. When the linear expansion coefficient exceeds this range, for example, when this multilayer polyimide film is bonded and laminated to a Si wafer, the deviation from the linear expansion coefficient of the Si wafer becomes large, and problems such as warpage and peeling tend to occur.
The tensile strength at break of the multilayer polyimide film of the present invention is not particularly limited, but is preferably 250 MPa or more, more preferably 300 MPa or more, and further preferably 350 MPa or more. When the tensile strength at break is lower than 250 MPa, film breakage tends to occur during conveyance, and the yield decreases.
Although the tensile elongation at break of the multilayer polyimide film of the present invention is not particularly limited, it is preferably 5% to 80%, more preferably 10% to 75%, and further preferably 15% to 70%. If the tensile elongation at break exceeds these ranges, film breakage tends to occur during conveyance, and the yield decreases.
The tensile elastic modulus of the multilayer polyimide film of the present invention is preferably 6.0 GPa or more, more preferably 6.5 GPa or more, and still more preferably 7.0 GPa or more.

  The method of multilayering (lamination) of the multilayer polyimide film of the present invention is not particularly limited as long as there is no problem in adhesion between both layers. For example, a method by coextrusion, layer (b) which is one layer A method of casting the other polyamic acid solution of the polyimide of the (a) layer on the polyimide film of (i) and imidizing this, the other ((b) layer of the polyimide film precursor film of the other layer ( a) A method of laminating a polyimide precursor film and imidizing together, and (b) a method of imidizing by applying a polyamic acid solution of polyimide (a) on the layer by spray coating, etc. A particularly preferable production method is a method for producing a multilayer polyimide film by coextrusion.

  The multilayer polyimide film in which the polyimide layer (a) is thinly formed on the surface of the (b) layer polyimide of the present invention maintains the high elastic modulus and low linear expansion coefficient of the (b) layer polyimide (film) almost as they are. In addition, the surface lubricity is improved. This multilayer polyimide film may be a (a) layer- (b) layer having a two-layer structure, but more preferably a three-layer structure (a) layer- (b) layer- (a) layer.

In the multilayer polyimide film of the present invention, the ratio of the thickness of the (a) layer and the (b) layer: (a) / (b) It is preferable that it is 0.005-0.5, More preferably, it is 0.01-0.2, More preferably, it is 0.01-0.1. When (a) / (b) is less than 0.005, the effect of improving the surface characteristics by the (a) layer may be insufficient, which is not preferable. On the other hand, when (a) / (b) exceeds 0.5, the high elastic modulus and low linear expansion coefficient of the (b) layer are impaired.
The thickness of the layer (a) in the multilayer polyimide film of the present invention is preferably 0.01 μm to 5 μm, more preferably 0.05 μm to 5 μm, and still more preferably 0.1 μm to 5 μm. When the (a) layer is less than 0.01 μm, the effect of improving the surface properties by the (a) layer may be insufficient, which is not preferable. On the other hand, when the (a) layer exceeds 5 μm, the high elastic modulus and the low linear expansion coefficient of the (b) layer are impaired.
Moreover, 1-50 micrometers is preferable, as for the thickness of the (b) layer of the multilayer polyimide film of this invention, More preferably, they are 2 micrometers-40 micrometers, More preferably, they are 3 micrometers-30 micrometers. (B) It is very difficult to form a very thin polyimide film and / or a very thick polyimide film having a layer exceeding this range.

The material of the inorganic fine particles used in the multi-layer polyimide film of the present invention is not particularly _{limited, SiO 2, TiO 2, B} 2 O 3, Al 2 O 3, Sb 2 O 3, BeO, MgO, CaO, metal oxides SrO, etc. , Metal nitrides such as AlN, orthophosphate compounds of group IIa alkaline earth metals (Be, Mg, Ca, Sr, Ra), carbonates of group IIa alkaline earth metals, Al, Ti, V , Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Mo, Ru, Rh, Pd, Ag, Cd, In, Sn, Sb, Ta, W, Pt, Au, Pb, Bi, C , Metals such as Si or metalloids, minerals, and alloys thereof, and the like may be used in combination. Among these, SiO ₂ can be preferably used.

  The average particle size of the inorganic fine particles used in the present invention is 0.05 μm to 2.5 μm, preferably 0.05 μm to 1.0 μm, more preferably 0.05 μm to 0.5 μm, still more preferably 0.05 μm to 0 μm. .1 μm. When the average particle diameter exceeds 2.5 μm, it is effective for forming protrusions on the film surface, but the film may be physically damaged to reduce the mechanical strength of the film. On the other hand, when the average particle size is smaller than 0.05 μm, coarse protrusions and the like are easily formed by secondary aggregation of the inorganic fine particles. Here, the average particle diameter in the present invention refers to a weight average particle diameter calculated from a particle diameter distribution obtained using a laser scattering particle size distribution analyzer (LB-500, manufactured by Horiba, Ltd.).

The CV value of the particle diameter of the inorganic particles used in the present invention is 25% or less, preferably 20% or less, more preferably 15% or less, and even more preferably 10% or less. The smaller the CV value, the better. However, the lower limit is about 1% for ease of production. The CV value of the particle diameter is a value obtained by dividing the standard deviation of the particle diameter by the average particle diameter, and is derived simultaneously in the measurement of the average particle diameter. A low CV value means a small variation in particle diameter.
Inorganic particles having the above average particle diameter and CV value are known per se, and examples thereof include metal fine particles obtained by a chemical reduction method and metal oxide fine particles obtained by a sol-gel method.

  Examples of means for containing inorganic particles in the polyimide film include means for blending inorganic particles in a solution of polyamic acid that is a precursor of the polyimide film. Specifically, before synthesizing the polyamic acid, inorganic particles are added and dispersed in an organic polar solvent, and then the acid anhydrides and diamines are reacted as described above. And means for adding inorganic particles after obtaining the polyamic acid solution. Preferably, among the above-mentioned means, means for adding and dispersing inorganic particles in an organic polar solvent before synthesizing the polyamic acid, or means for adding inorganic particles during the reaction between the polyamic acid and the diamine are mentioned. It is done. By such means, the inorganic particles are hardly aggregated and can be uniformly dispersed efficiently.

In the multilayer polyimide film of the present invention, it is necessary that (a) layer contains 0.5 to 50% by mass of inorganic fine particles, and (b) layer contains 0.1% by mass or less of inorganic fine particles. It is.
The content of the inorganic fine particles in the layer (a) is preferably 1.0% by mass to 50% by mass, more preferably 5.0% by mass to 50% by mass, and further preferably 10% by mass to 50% by mass. It is. Moreover, it is preferable that content of the inorganic fine particle in a (b) layer is 0.05 mass% or less, More preferably, it is 0.02 mass% or less. When the content of the inorganic particles in the layer (a) exceeds 50% by weight, the mechanical strength of the film is greatly lowered, and it is difficult to form a film. On the other hand, if it is less than 0.5% by weight, the effect of improving slipperiness is small, which is not preferable. Moreover, when content of the inorganic particle in (b) layer exceeds 0.1 weight%, a high elastic modulus may not be achieved as a multilayer polyimide film. It is particularly preferred that the layer (b) does not contain inorganic particles.
By using a multilayer polyimide film having the above-described structure, irregularities are formed on the surface, and the lubricity is improved. Further, the amount of lubricant to be used is reduced as a whole film, which is advantageous in terms of cost.

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated more concretely, this invention is not limited by a following example. In addition, the evaluation method of the physical property in the following examples is as follows.

1. Reduced viscosity of polyamic acid (ηsp / C)
A solution dissolved in N-methyl-2-pyrrolidone (or N, N-dimethylacetamide) so that the polymer concentration was 0.2 g / dl was measured at 30 ° C. with an Ubbelohde type viscosity tube.

2. The thickness of the polyimide film The polyimide film to be measured was measured using a micrometer (Minetron 1245D, manufactured by Fine Reef).

3. Tensile modulus of elasticity, tensile strength at break, and elongation at break of polyimide film are subjected to a tensile fracture test under the following conditions, and the tensile modulus of elasticity in the width direction (TD direction) and the longitudinal direction (MD direction), Tensile rupture strength and tensile rupture elongation were measured.
Device name: Autograph made by Shimadzu Corporation
Sample length: 100mm
Sample width: 10mm
Pulling speed: 50mm / min
Distance between chucks: 40 mm

4). Linear expansion coefficient (CTE) of polyimide film
For the polyimide film to be measured, the stretch rate in the MD direction and the TD direction is measured under the following conditions, and the stretch rate / temperature at intervals of 90 to 100 ° C., 100 to 110 ° C.,. The measurement was performed up to 400 ° C., and the average value of all measured values from 100 ° C. to 350 ° C. was calculated as CTE (ppm / ° C.).
Device name: TMA4000S manufactured by MAC Science
Sample length: 10mm
Sample width: 2mm
Initial load: 34.5 g / mm ²
Temperature rise start temperature: 25 ° C
Temperature rise end temperature: 400 ° C
Temperature increase rate: 5 ° C / min
Atmosphere: Argon

5). Average Particle Diameter of Inorganic Fine Particles The inorganic fine particles to be measured were dispersed in a solvent, the particle diameter distribution was determined with a laser scattering particle size distribution analyzer LB-500 manufactured by Horiba, Ltd., and the weight average particle diameter was calculated.

6). Evaluation of multilayer polyimide film: heat resistance The appearance of the multilayer polyimide film that did not show any discoloration in the N ₂ atmosphere after heat treatment at 400 ° C. for 18 hours was evaluated as “◯”, and the one that showed discoloration as “×”. .

7). Evaluation of multilayer polyimide film: slipperiness When two films were overlapped, the stacked films were sandwiched between the thumb and forefinger and rubbed lightly, the case where the film and the film slipped was evaluated as ◯, and the case where the film did not slide was evaluated as ×.

8). Evaluation of multilayer polyimide film: roll winding property When winding a long multilayer polyimide film on a winding roll (outer diameter of mandrel: 15 cm) at a speed of 2 m / min, it is smoothly wound without wrinkles The case where the take-up was possible was marked with ◯, the case where wrinkles were partially generated was marked with Δ, and the case where wrinkles were generated or the roll was wound around and could not be smoothly wound was marked with x.

[Production Examples 1 to 9]
(Preparation of polyamic acid solutions A1 to A9)
The inside of the reaction vessel equipped with a nitrogen introduction tube, a thermometer, and a stirring rod was purged with nitrogen, and then 223 parts by mass of 5-amino-2- (p-aminophenyl) benzoxazole and 4416 parts by mass of N, N-dimethylacetamide were added. After complete dissolution, 217 parts by mass of pyromellitic dianhydride and Snowtex (DMAC-ST30, manufactured by Nissan Chemical Industries), in which colloidal silica is dispersed in dimethylacetamide, are listed in Table 1 and Table 2. When stirred for 24 hours at a reaction temperature of 25 ° C., brown and viscous polyamic acid solutions A1 to A9 were obtained.

(Examples 1-8)
The polyamic acid solution A1 and the polyamic acid solutions A3 to A8 were coated on a stainless steel belt using a three-layer coextrusion T-die. Here, A1 was used as the (b) layer, and A3 to A8 were used as the (a) layer. Next, the polyamic acid film having self-supporting property obtained by drying at 110 ° C. for 5 minutes is peeled from the stainless steel belt, passed through a pin tenter having three heat treatment zones, and the first stage is 150 ° C. × 2 minutes. Heat treatment at 220 ° C for 2 minutes and 475 ° C for 4 minutes at the 3rd stage, 6 rolls are passed through for 20 minutes after passing through the tenter, giving a double-sided free process, and finally slitting to 500 mm width The multilayer polyimide films of Examples 1 to 8 were obtained.
Table 3 shows the physical property values of the obtained multilayer polyimide films of Examples 1 to 8. In addition, the thickness of the (a) layer in a table | surface shows the sum total of the thickness of front and back (a) layer.

(Comparative Examples 1-3)
The polyamic acid solution A1 and the polyamic acid solutions A1 and A2 were coated on a stainless steel belt using a three-layer coextruded T-die. Here, A1 was used as the (b) layer, and A1 and A2 were used as the (a) layer. Next, the polyamic acid film having self-supporting property obtained by drying at 110 ° C. for 5 minutes is peeled from the stainless steel belt, passed through a pin tenter having three heat treatment zones, and the first stage is 150 ° C. × 2 minutes. Heat treatment at 220 ° C for 2 minutes and 475 ° C for 4 minutes at the 3rd stage, 6 rolls are passed through for 20 minutes after passing through the tenter, giving a double-sided free process, and finally slitting to 500 mm width The multilayer polyimide films of Comparative Examples 1 to 3 were obtained.
Table 4 shows physical property values of the obtained multilayer polyimide films of Comparative Examples 1 to 3. In addition, “impossible” in the table indicates that a film of good quality cannot be obtained and measurement is impossible.

(Comparative Examples 4-6)
The polyamic acid solutions A7 to A9 and the polyamic acid solution A6 were coated on a stainless steel belt using a three-layer coextrusion T-die. Here, A7 to A9 were used as the (b) layer and A6 as the (a) layer. Next, the polyamic acid film having self-supporting property obtained by drying at 110 ° C. for 5 minutes is peeled from the stainless steel belt, passed through a pin tenter having three heat treatment zones, and the first stage is 150 ° C. × 2 minutes. Heat treatment at 220 ° C for 2 minutes and 475 ° C for 4 minutes at the 3rd stage, 6 rolls are passed through for 20 minutes after passing through the tenter, giving a double-sided free process, and finally slitting to 500 mm width The multilayer polyimide films of Comparative Examples 4 to 6 were obtained.
Table 4 shows the physical property values of the obtained multilayer polyimide films of Comparative Examples 4 to 6. These polyimide films had poor slipperiness because the surface layer was very brittle and easily peeled off.

(Comparative Examples 7 to 13)
The polyamic acid solutions A3 to A9 were coated on a stainless steel belt using a T-type die. Next, the polyamic acid film having self-supporting property obtained by drying at 110 ° C. for 5 minutes is peeled from the stainless steel belt, passed through a pin tenter having three heat treatment zones, and the first stage is 150 ° C. × 2 minutes. Heat treatment at 220 ° C for 2 minutes and 475 ° C for 4 minutes at the 3rd stage, 6 rolls are passed through for 20 minutes after passing through the tenter, giving a double-sided free process, and finally slitting to 500 mm width The monolayer polyimide films of Comparative Examples 7 to 13 were obtained.
Table 5 shows the physical property values of the single-layer polyimide films of Comparative Examples 7 to 13 obtained. These polyimide films are generally very fragile and difficult to transport.

  A) layer of the present invention: obtained by reacting an aromatic tetracarboxylic acid and an aromatic diamine containing 0.5 to 50% by mass of inorganic fine particles having an average particle size of 0.05 to 2.5 μm A layer mainly composed of polyimide and (b) layer: aromatic tetracarboxylic acids and aromatics having a content of inorganic fine particles having an average particle size of 0.05 to 2.5 μm of 0.1% by mass or less A multilayer polyimide film having a tensile modulus of elasticity in the longitudinal direction and a tensile modulus of elasticity in the width direction of 6.0 GPa or more obtained by laminating a layer mainly composed of polyimide obtained by reacting with a diamine is a lubricant such as fine particles. It is contained in a small amount with respect to the whole film, so that the original physical properties of the film are hardly lost, and it becomes a slippery and easy-sliding multilayer polyimide film. It is effective for insulating substrates such as substrates and circuit boards, and is extremely significant industrially.

Claims (4)

A multilayer polyimide film characterized in that at least the following layers (a) and (b) are laminated, and the tensile modulus in the longitudinal direction and the tensile modulus in the width direction are both 6.0 GPa or more.
(A) Layer: polyimide obtained by reacting aromatic tetracarboxylic acids and aromatic diamines, containing 0.5 to 50% by mass of inorganic fine particles having an average particle size of 0.05 to 2.5 μm A layer mainly composed of
(B) Layer: A polyimide obtained by reacting aromatic tetracarboxylic acids and aromatic diamines, wherein the content of inorganic fine particles having an average particle size of 0.05 to 2.5 μm is 0.1% by mass or less. The main component layer.   The multilayer polyimide film according to claim 1, wherein the multilayer polyimide film has a three-layer structure of (a) layer- (b) layer- (a) layer.   (A) Layer to (b) layer thickness ratio: (a) / (b) is 0.005 to 0.5, and (a) layer thickness is 0.01 μm to 5 μm, (b The multilayer polyimide film according to claim 1, wherein the layer has a thickness of 1 μm to 50 μm.   The polyimide is a polyimide having at least pyromellitic acid as a residue of aromatic tetracarboxylic acids and a benzoxazole structure as a residue of aromatic diamines, and has a linear expansion coefficient in the plane direction of −10 ppm / ° C. to 10 ppm / The multilayer polyimide film according to any one of claims 1 to 3, which is at ° C.