JP6639249B2 - Polyimide film with adhesive - Google Patents

Description

  The present invention relates to a polyimide film with an adhesive useful for manufacturing a flat cable manufactured by sandwiching a conductor between two substrates having an adhesive layer and an insulator layer, and a polyimide film with the adhesive. Related to the configured flat cable.

  Flat cables are widely used in electric devices such as mobile phones, tablets, and hard disks of personal computers. In a flat cable, a conductor such as a copper foil formed in a wiring shape is arranged between a substrate having an insulator layer and an adhesive layer (or simply referred to as “substrate for flat cable”). It is manufactured by sandwiching it between the adhesive layers.

  Generally, a polyethylene terephthalate film (PET film) is used for the insulator layer of the flat cable. Therefore, the conventional flat cable has a problem that the heat resistance is not sufficient and the dimensional change rate of the flat cable due to heat is large.

  As a flat cable having excellent heat resistance, Patent Document 1 discloses a polyimide film with an adhesive using an epoxy having a glass transition temperature and a curing temperature in a specific range using a polyimide film as an insulating layer and an adhesive layer. A flat cable which is formed and further has a specific range of a longitudinal elastic modulus and an elongation of a polyimide film with an adhesive and a specific range of 180 ° peel strength between an adhesive layer and a conductor is described. In addition, Patent Document 1 does not specifically describe a polyimide film used as an insulating layer of a base material for a flat cable, and does not describe physical properties and compositions of the polyimide film. Further, what is described in Patent Literature 1 is the bending resistance of the flat cable under heating conditions, and the dimensional change rate of the flat cable due to heat is not described in Patent Literature 1.

  In addition, Patent Document 2 discloses that, as an insulator layer, a polyimide film whose main component is a polyimide obtained by reacting an aromatic tetracarboxylic acid and an aromatic diamine and has a linear expansion coefficient of 10 ppm / ° C. or less is used. Further, a high heat-resistant flat cable using one or more adhesives selected from polyimide or polyamideimide having a 5% weight loss temperature of 400 ° C. or more as an adhesive layer is described. Patent Literature 2 describes that such a flat cable can be used for a long time even at a temperature of 150 ° C or higher. In addition, what is measured as an evaluation item of heat resistance in Patent Document 2 is the peel strength between the polyimide film and the adhesive layer after heat treatment at 400 ° C. for 1 hour and the appearance (the presence or absence of discoloration and blistering). No specific evaluation of the dimensional stability of the flat cable is performed in Patent Document 2.

  Patent Document 3 discloses that a flat cable is formed by coating a hot-melt adhesive containing a residual organic solvent on a synthetic resin base film, sandwiching both sides of the conductor and bonding the hot-melt adhesives to each other. In the adhesive film to be composed, the temperature at which the needle penetration rate of the hot melt adhesive becomes 50% as measured by the needle penetration method TMA under the conditions of a heating rate of 5 ° C. per minute, a load of 0.49 N, and a probe diameter of 0.5 mm is as follows. It is described that an adhesive film having a temperature lower by 0.1 to 5 ° C. than a hot-melt adhesive containing no organic solvent has good lamination speed and anti-blocking property at the time of flat cable production. Note that Patent Document 3 does not specifically disclose an example using a polyimide film as a synthetic resin base film, and does not specifically disclose the physical properties and composition of the polyimide film. Further, Patent Document 3 does not describe heat resistance and dimensional stability due to heat of the flat cable.

Patent No. 4292729 JP 2009-93817 A JP 2012-21079 A

An object of the present invention is to provide a base material for a flat cable that is useful for manufacturing a flat cable and the like.
Another object of the present invention is to provide a flat cable base material having excellent heat resistance.
Still another object of the present invention is to provide a flat cable having excellent heat resistance (and dimensional stability due to heat).

The present inventors have conducted intensive studies to solve the above problems, and as a result, using a polyimide film with an adhesive obtained by laminating an adhesive layer on a polyimide film having specific physical properties, as a base material for a flat cable. Tried.
Specifically, a polyimide film having a small heat shrinkage (specifically, a polyimide film having a heat shrinkage of 0.2% or less after heating at 200 ° C. for 60 minutes) is generally used in the production of flat cables. An attempt was made to use a polyimide film with an adhesive obtained by laminating an adhesive layer of an adhesive to be used (for example, a polyester-based adhesive) as a base material for a flat cable.
However, such a polyimide film with an adhesive does not have sufficient heat resistance, and when used as a base material for a flat cable, the dimensional change of the flat cable due to heat is large.

The inventors of the present invention have conducted intensive studies on the polyimide film and the adhesive layer, and as a result, have found that bonding with a concept completely different from the concept of Patent Document 3 (improvement of laminating speed and blocking resistance in flat cable production). Attention was paid to the penetration amount into the needle in the TMA needle penetration mode measurement of the agent layer.
Further, the present inventors have found that the penetration amount of the needle into the polyimide film having a thermal shrinkage of 0.2% or less after heating at 200 ° C. for 60 minutes at 180 ° C. in the TMA needle insertion mode measurement is within a specific range. A polyimide film with an adhesive layered with an adhesive layer (an adhesive layer having a needle penetration at 180 ° C. in the TMA needle penetration mode measurement of 40% or more of the thickness of the adhesive layer). It has been found that when used as a base material for a flat cable, a flat cable having excellent heat resistance and dimensional stability due to heat can be formed.

  In addition, when a flat cable is formed by sandwiching a conductor between flat cable base materials and heating the same, particularly when a thermosetting resin (for example, an epoxy resin or the like) is used for the adhesive layer of the flat cable base material, the flat cable is used. Although a gap is easily generated between the conductors of the cable, the present inventors defined the adhesive layer so that the penetration amount into the needle at 180 ° C. of the TMA needle penetration mode measurement falls within the above specific range. And found that a gap is hardly generated between conductors of the flat cable.

The present invention relates to the following polyimide film with an adhesive.
[1] A polyimide film having a heat shrinkage of 0.2% or less after heating at 200 ° C. for 60 minutes and an adhesive layer, and the penetration amount of the adhesive layer into the needle at 180 ° C. in the TMA needle insertion mode measurement. Is a polyimide film with an adhesive having a thickness of 40% or more of the thickness of the adhesive layer.
[2] The amount of penetration of the needle into the needle with respect to the thickness of the adhesive layer in the TMA needle penetration mode measurement is 5% or less at 100 ° C., and the needle at 140 ° C. The polyimide film with an adhesive according to the above [1], wherein the penetration amount is 20% or more.
[3] The polyimide film with an adhesive according to [1] or [2], wherein the polyimide film has a surface roughness Rmax of 0.6 μm or more and Rz of 0.3 μm or more.
[4] The polyimide film comprises one or more aromatic diamine components selected from the group consisting of paraphenylenediamine, 4,4′-diaminodiphenyl ether and 3,4′-diaminodiphenyl ether, and pyromellitic dianhydride and / or The polyimide film with an adhesive according to any one of the above [1] to [3], which contains, as a raw material, an aromatic acid anhydride component of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride.
[5] The polyimide film with an adhesive according to any of [1] to [4], wherein the adhesive layer includes an adhesive component containing an epoxy resin and an additive containing another resin.
[6] The polyimide film with an adhesive according to any one of [1] to [5] for use in manufacturing a flat cable.
[7] A flat cable in which a conductor is sandwiched between a pair of the polyimide films with an adhesive according to any one of the above [1] to [6].
[8] The flat cable according to [7], further including a polyimide film having a thickness of 50 to 500 μm, or a reinforcing plate in which a plurality of polyimide films are stacked.

INDUSTRIAL APPLICABILITY The polyimide film with an adhesive of the present invention is useful as a base material for a flat cable useful for production of a flat cable and the like.
Further, the polyimide film with an adhesive of the present invention can be used as a base material for a flat cable having excellent heat resistance, and can be used even at a high temperature (for example, 180 ° C. or higher) which cannot be used with a PET film. .
Further, the polyimide film with an adhesive of the present invention can be used as a base material for a flat cable excellent in heat resistance, and provides a flat cable excellent in heat resistance (and dimensional stability due to heat). Can be.

Hereinafter, the present invention will be described in more detail.
The polyimide film with an adhesive of the present invention has a polyimide film having a specific heat shrinkage and an adhesive layer. The polyimide film with an adhesive usually has an adhesive layer on one side of the polyimide film. In the polyimide film with an adhesive, another layer may be further laminated on the polyimide film surface side.

[Polyimide film]
In obtaining a polyimide film, first, an aromatic diamine component and an aromatic acid anhydride component are polymerized in an organic solvent to obtain a polyamic acid solution (hereinafter, also referred to as a polyamic acid solution).
The polyamic acid solution can be obtained by polymerizing a chemical substance having an aromatic diamine component and an aromatic acid anhydride component as main components in an organic solvent.

  Examples of the aromatic diamine component include paraphenylenediamine, metaphenylenediamine, benzidine, paraxylylenediamine, 4,4′-diaminodiphenylether, 3,4′-diaminodiphenylether, 4,4′-diaminodiphenylmethane, 4'-diaminodiphenylsulfone, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, 1,5-diaminonaphthalene, 3,3'-dimethoxybenzidine, 1,4-bis (3-methyl-5-amino Phenyl) benzene and their amide-forming derivatives. These may be used alone or as a mixture of two or more.

  As the aromatic diamine component, paraphenylenediamine, 4,4′-diamino is preferred from the viewpoint that a polyimide film with an adhesive is excellent in heat resistance and excellent in heat resistance and dimensional stability due to heat when a flat cable is formed. One or more selected from the group consisting of diphenyl ether and 3,4'-diaminodiphenyl ether is preferred, and a combination of paraphenylenediamine and 4,4'-diaminodiphenyl ether is more preferred.

As a raw material used for forming the polyamic acid solution, a diamine component other than the aromatic diamine component may be contained as long as the effects of the present invention are not impaired.
Other diamine components include, for example, 3,3′-diaminodiphenyl ether, 4,4′-diaminodiphenylpropane, 3,4′-diaminodiphenylpropane, 3,3′-diaminodiphenylpropane, 3,4′-diamino Diphenylmethane, 3,3'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfide, 3,4'-diaminodiphenylsulfide, 3,3'-diaminodiphenylsulfide, 3,4'-diaminodiphenylsulfone, 3,3 ' -Diaminodiphenylsulfone, 2,6-diaminopyridine, bis- (4-aminophenyl) diethylsilane, 3,3'-dichlorobenzidine, bis- (4-aminophenyl) ethylphosphinoxide, bis- (4- Aminophenyl) phenylphosphinoxide, bis- (4- (Minophenyl) -N-phenylamine, bis- (4-aminophenyl) -N-methylamine, 1,5-diaminonaphthalene, 3,3′-dimethyl-4,4′-diaminobiphenyl, 3,4′-dimethyl -3 ′, 4-diaminobiphenyl-3,3′-dimethoxybenzidine, 2,4-bis (p-β-amino-t-butylphenyl) ether, bis (p-β-amino-t-butylphenyl) Ether, p-bis (2-methyl-4-aminopentyl) benzene, p-bis- (1,1-dimethyl-5-aminopentyl) benzene, m-xylylenediamine, p-xylylenediamine, 1,3 -Diaminoadamantane, 3,3'-diamino-1,1'-diaminoadamantane, 3,3'-diaminomethyl-1,1'-diadamantane, bis (p-aminocyclohexyl ) Methane, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, 3-methylheptamethylenediamine, 4,4′-dimethylheptamethylenediamine, 2,11-diaminododecane, 1,2 -Bis (3-aminopropoxy) ethane, 2,2-dimethylpropylenediamine, 3-methoxyhexaethylenediamine, 2,5-dimethylhexamethylenediamine, 2,5-dimethylheptamethylenediamine, 5-methylnonamethylenediamine, 1 , 4-Diaminocyclohexane, 1,12-diaminooctadecane, 2,5-diamino-1,3,4-oxadiazole, 2,2-bis (4-aminophenyl) hexafluoropropane, N- (3-amino Phenyl) -4-amino Nzuamido, 4-aminophenyl-3-aminobenzoate, and the like. These may be used alone or as a mixture of two or more.

  Specific examples of the aromatic acid anhydride component include, for example, pyromellitic acid, 3,3 ′, 4,4′-biphenyltetracarboxylic acid, 2,3 ′, 3,4′-biphenyltetracarboxylic acid, 3 ', 4,4'-benzophenonetetracarboxylic acid, 2,3,6,7-naphthalenetetracarboxylic acid, 2,2-bis (3,4-dicarboxyphenyl) ether, pyridine-2,3,5 Acid anhydride components of aromatic tetracarboxylic acids such as 6-tetracarboxylic acid and amide-forming derivatives thereof are exemplified. These may be used alone or as a mixture of two or more.

  As the aromatic acid anhydride component, pyromellitic dianhydride and / or from the viewpoint that the polyimide film with an adhesive has excellent heat resistance and excellent heat resistance and dimensional stability due to heat when a flat cable is formed. Or 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride is preferred.

In the present invention, the raw material used for forming the polyamic acid solution may contain an acid anhydride component other than the aromatic acid anhydride component as long as the effects of the present invention are not impaired.
Other acid anhydride components include, for example, 1,2,4,5-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 1,4,5,8 -Decahydronaphthalenetetracarboxylic dianhydride, 4,8-dimethyl-1,2,5,6-hexahydronaphthalenetetracarboxylic dianhydride, 2,6-dichloro-1,4,5,8-naphthalene Tetracarboxylic dianhydride, 2,7-dichloro-1,4,5,8-naphthalenetetracarboxylic dianhydride, 2,3,6,7-tetrachloro-1,4,5,8-naphthalenetetra Carboxylic dianhydride, 1,8,9,10-phenanthrenetetracarboxylic dianhydride, 2,2-bis (2,3-dicarboxyphenyl) propane dianhydride, 1,1-bis (3,4 -Dicarboxyphenyl Ethane dianhydride, 1,1-bis (2,3-dicarboxyphenyl) ethane dianhydride, bis (2,3-dicarboxyphenyl) methane dianhydride, bis (3,4-dicarboxyphenyl) methane Dianhydride, bis (3,4-dicarboxyphenyl) sulfone dianhydride, benzene-1,2,3,4-tetracarboxylic dianhydride, 3,4,3 ′, 4′-benzophenonetetracarboxylic acid And dianhydrides. These may be used alone or as a mixture of two or more.

  In the present invention, as the combination of the aromatic diamine component and the acid anhydride component, at least one aromatic diamine component selected from the group consisting of paraphenylenediamine, 4,4′-diaminodiphenyl ether and 3,4′-diaminodiphenyl ether And a combination of a pyromellitic dianhydride and / or an aromatic acid anhydride component of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride.

  When the aromatic diamine component contains paraphenylenediamine and 4,4′-diaminodiphenyl ether, the molar ratio between paraphenylenediamine and 4,4′-diaminodiphenyl ether is preferably 50/50 to 0/100, and 40 / 60 to 0/100 is more preferable.

  When the aromatic acid anhydride component contains pyromellitic dianhydride and 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, pyromellitic dianhydride and 3,3 ′, 4,4 The molar ratio of '-biphenyltetracarboxylic dianhydride is preferably from 100/0 to 50/50, and more preferably from 100/0 to 60/40.

  Specific examples of the organic solvent used for forming the polyamic acid solution include, for example, sulfoxide solvents such as dimethyl sulfoxide and diethyl sulfoxide, and formamide solvents such as N, N-dimethylformamide and N, N-diethylformamide. , Acetamide solvents such as N, N-dimethylacetamide, N, N-diethylacetamide, pyrrolidone solvents such as N-methyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, phenol, o-, m-, or Examples include phenolic solvents such as p-cresol, xylenol, halogenated phenol, and catechol, and aprotic polar solvents such as hexamethylphosphoramide and γ-butyrolactone. These can be used alone or in combination of two or more, and further can be used in combination with aromatic hydrocarbons such as xylene and toluene.

The polymerization method of the polyamic acid solution may be performed by any known method, for example,
(1) a method in which the whole amount of the aromatic diamine component is first put in a solvent, and then the aromatic acid anhydride component is added to the whole amount of the aromatic diamine component so as to be equivalent to the polymerization;
(2) a method in which the whole amount of the aromatic acid anhydride component is first put into a solvent, and then the aromatic diamine component is added so as to be equivalent to the aromatic acid anhydride component, followed by polymerization.
(3) After putting one aromatic diamine component into a solvent, mixing one aromatic acid anhydride component at a ratio of 95 to 105 mol% with respect to the reaction component for a time required for the reaction, and then mixing A method in which one aromatic diamine component is added, and then the other aromatic acid anhydride component is added and polymerized so that the total aromatic diamine component and the total aromatic acid anhydride component are substantially equivalent,
(4) One aromatic acid anhydride component is put in a solvent, and then one aromatic diamine component is mixed with the reaction component in a ratio of 95 to 105 mol% for a time necessary for the reaction, and then mixed. A method in which one aromatic acid anhydride component is added, and then the other aromatic diamine component is added and polymerized so that the total aromatic diamine component and the total aromatic acid anhydride component are substantially equivalent,
(5) A polyamic acid solution (A) is prepared by reacting one aromatic diamine component and an aromatic acid anhydride component in a solvent so that either one is in excess, and the other aromatic diamine component is used in another solvent. The polyamic acid solution (B) is prepared by reacting the diamine component and the aromatic acid anhydride component so that either one becomes excessive. A method in which the polyamic acid solutions (A) and (B) thus obtained are mixed to complete the polymerization. At this time, if the aromatic diamine component is excessive when preparing the polyamic acid solution (A), the polyamic acid solution (B) excessively contains the aromatic acid anhydride component, and the polyamic acid solution (A) uses the aromatic acid anhydride. When the amount of the components is excessive, the polyamic acid solution (B) contains an excess of the aromatic diamine component, and the polyamic acid solutions (A) and (B) are mixed, and the wholly aromatic diamine component and the wholly aromatic compound used in these reactions are mixed. A method of adjusting the acid anhydride component so that it is substantially equivalent to the acid anhydride component, and the like.
The polymerization method is not limited to these, and other known methods may be used.

  In the present invention, the aromatic acid anhydride component and the aromatic diamine component constituting the polyamic acid are polymerized in such a ratio that their mole numbers are substantially equal, and one of them is 10 mole%, preferably 5 mole%. It may be blended in excess of the other in the range.

  The polymerization reaction is preferably performed while stirring in an organic solvent. Although the polymerization temperature is not particularly limited, it is usually carried out at an internal temperature of the reaction solution of 0 to 80 ° C. The polymerization time is not particularly limited, but is preferably continuously performed for 10 minutes to 30 hours. As necessary, the polymerization reaction may be performed by dividing the polymerization reaction or raising or lowering the temperature. The order of addition of both reactants is not particularly limited, but it is preferable to add the aromatic acid anhydride to the solution of the aromatic diamine component. Vacuum degassing during the polymerization reaction is an effective method for producing a high-quality organic solvent solution of polyamic acid. Further, the polymerization reaction may be controlled by adding a small amount of a terminal blocking agent to the aromatic diamine before the polymerization reaction. The terminal blocking agent is not particularly limited, and a known one can be used.

  The polyamic acid solution thus obtained usually contains 5 to 40% by weight, preferably 10 to 30% by weight of solids. The viscosity is a value measured by a Brookfield viscometer, and is not particularly limited, but is usually 10 to 2000 Pa · s (100 to 20000 poise), and is preferably 100 to 1000 Pa · s for stable liquid sending. (1000 to 10,000 poise). The polyamic acid in the organic solvent solution may be partially imidized.

By heating the polyamic acid solution, a polyimide film can be manufactured.
As a method for producing a polyimide film, for example, a method of casting a polyamic acid solution into a film and thermally decyclizing and desolvating to obtain a polyimide film, mixing a cyclization catalyst and a dehydrating agent with the polyamic acid solution, and then chemically There is a method in which a gel film is prepared by subjecting to a decyclization to obtain a polyimide film by heating and desolvating the gel film. The latter is more preferable.

  In the method of chemically decyclizing, first, the above polyamic acid solution is prepared. The polyamic acid solution can contain a cyclization catalyst (imidization catalyst), a dehydrating agent, a gelling retarder, and the like.

  Specific examples of the cyclization catalyst include aliphatic tertiary amines such as trimethylamine and triethylenediamine, aromatic tertiary amines such as dimethylaniline, and heterocyclic tertiary amines such as isoquinoline, pyridine and β-picoline. These can be used alone or in combination of two or more. Of these, an embodiment in which at least one heterocyclic tertiary amine is used is preferred.

  Specific examples of the dehydrating agent include acetic anhydride, propionic anhydride, aliphatic carboxylic anhydrides such as butyric anhydride, and aromatic carboxylic anhydrides such as benzoic anhydride, among which acetic anhydride and / or Benzoic anhydride is preferred.

  As a method of producing a polyimide film from a polyamic acid solution, for example, a polyamic acid solution containing a cyclization catalyst and a dehydrating agent is cast on a support from a die having a slit or the like, and formed into a film, A method of obtaining a polyimide film by performing a part of the imidization above to form a gel film having self-supporting properties, peeling the gel film from the support, and performing heat treatment.

  The polyamic acid solution is cast on a heated support, undergoes a ring closure reaction on the support, and is separated from the support as a gel film having self-supporting properties.

  The support is a rotating drum or an endless belt made of metal, and its temperature is controlled by a liquid or gas heat medium and / or radiant heat from an electric heater or the like.

  The gel film is heated to a temperature of usually 30 to 200 ° C., preferably 40 to 150 ° C., and receives a heat from a support and / or a heat source such as a hot air or an electric heater to undergo a ring-closing reaction, thereby releasing an organic solvent or the like. By drying the volatiles of the resin, it becomes self-supporting and is separated from the support.

  The gel film peeled from the support is usually stretched in the running direction while controlling the running speed by a rotating roll. Stretching is usually performed at a temperature of 140 ° C. or lower at a magnification of 1.01 to 1.90, preferably 1.05 to 1.60, and more preferably 1.10 to 1.50. The gel film stretched in the running direction is introduced into a tenter device, the both ends in the width direction are gripped by the tenter clips, and is stretched in the width method while running with the tenter clips.

  The stretched gel film is usually heated by air, an infrared heater or the like for 15 seconds to 30 minutes. Next, heat treatment is usually performed at a temperature of 250 to 500 ° C. for 15 seconds to 30 minutes using hot air and / or an electric heater.

  Further, the thickness of the polyimide film can be adjusted by the traveling speed. The thickness of the polyimide film may be appropriately selected according to the intended thickness of the laminated film, the number of polyimide films to be used, and the like.

  Further annealing of the polyimide film thus obtained can reduce the heat shrinkage (specifically, the heat shrinkage after heating at 200 ° C. for 60 minutes is 0.2% or less. It is preferable from the viewpoints such as: The method of the annealing treatment is not particularly limited, and may be in accordance with a conventional method. The temperature of the annealing treatment is not particularly limited, but is preferably 200 to 500 ° C, more preferably 200 to 370 ° C, and particularly preferably 210 to 350 ° C. Specifically, it is preferable that the film be run under low tension in a furnace heated to the above-mentioned temperature range to perform the annealing treatment. The time during which the film stays in the furnace is the processing time. The processing time is controlled by changing the running speed, and the processing time is preferably 5 seconds to 5 minutes. The film tension during running is preferably from 10 to 50 N / m, and more preferably from 20 to 30 N / m.

The polyimide film may include a filler (for example, an inorganic particle, an organic filler, and the like), and preferably includes an inorganic particle.
The content of the filler in the polyimide film is not particularly limited, but may be, for example, about 0.03 to 1% by weight, and preferably about 0.05 to 0.8% by weight, per 1 weight of the film resin.

  The method for adding a filler to the polyimide film is not particularly limited, but a filler may be added to the above-described polyamic acid solution. The filler may be added to a previously polymerized polyamic acid solution, or the polyamic acid solution may be polymerized in the presence of the filler.

The polyimide film has a heat shrinkage after heating at 200 ° C. for 60 minutes of usually 0.2% or less (for example, 0.01 to 0.15%), preferably 0.15% or less (for example, 0.01 to 0.1%). 0.1%), preferably 0.1% or less (for example, 0.01 to 0.07%). The heat shrinkage of the polyimide film after heating at 200 ° C. for 60 minutes is determined by measuring the film size (L1) of the polyimide film after being left for 2 hours or more in a room adjusted to 25 ° C. and 60% RH, using the CNC image processing system NEXIV VM-. 250 (manufactured by Nikon), followed by heating at 200 ° C. for 60 minutes and then again standing in a room adjusted to 25 ° C. and 60% RH for 1 day to determine the film size (L2) by the CNC image. It can be measured by using a processing device system and calculated by the following equation.
Heat shrinkage (%) =-{(L2-L1) / L1} × 100

  The average coefficient of linear expansion of the polyimide film is not particularly limited, but is, for example, 0 to 100 ppm / ° C, preferably 0 to 50 ppm / ° C, and more preferably 3 to 35 ppm / ° C. The thermal expansion coefficient can be measured using a TMA-50 manufactured by Shimadzu Corporation under the conditions of a measurement temperature range: 50 to 200 ° C., and a temperature rising rate: 10 ° C./min.

The surface roughness Rmax of the polyimide film is preferably 0.6 μm or more (for example, 0.6 to 0.6 μm) from the viewpoint of improving the adhesiveness between the adhesive layer and the reinforcing plate attached to the surface opposite to the adhesive layer. 2 μm). Further, the surface roughness Rz of the polyimide film may be preferably about 0.3 μm or more (for example, 0.3 to 1.2 μm) from the viewpoint of improving the adhesion to the adhesive layer. The measurement of the surface roughness of the polyimide film may be performed in accordance with JIS B 0601 (2001).
A method for obtaining a polyimide film having such a surface roughness is not particularly limited, and for example, can be obtained by a known surface treatment (for example, a wet blast treatment, a sand mat treatment, a resin mat treatment, a plasma treatment, or the like). it can. The surface treatment may be performed on one side or both sides of the polyimide film.

[Adhesive layer]
As the adhesive, an adhesive capable of forming an adhesive layer whose penetration amount into the needle at 180 ° C. in the TMA needle insertion mode measurement is 40% or more of the thickness of the adhesive layer is preferable.

The adhesive layer only needs to contain an adhesive component.
Examples of the adhesive component include a thermoplastic resin (for example, a polyamide resin), a thermosetting resin (for example, an unsaturated polyester resin, an epoxy resin, and the like), and a thermosetting resin is preferable.

  The adhesive layer may contain an additive as long as the adhesiveness is not impaired. As the additive, for example, a resin that is not included in the category of a flame retardant, an antioxidant, a cross-linking agent, or an adhesive component. For example, an elastomer (for example, a styrene-based elastomer) can be used. In particular, from the viewpoint of forming an adhesive layer whose penetration amount into needle at 180 ° C. in the TMA needle insertion mode measurement is at least 40% of the thickness of the adhesive layer, it is preferable to include an additive.

  Further, the adhesive layer may contain a solvent (for example, an aromatic hydrocarbon-based solvent such as toluene or xylene, or a ketone-based solvent such as methyl ethyl ketone or dimethyl ketone).

  In the adhesive layer, the additive is, for example, 1.5 to 200 parts by weight (for example, 2 to 170 parts by weight), preferably 2 to 150 parts by weight (for example, 3 to 140 parts by weight) based on 1 part by weight of the adhesive component. Parts by weight), more preferably about 3 to 120 parts by weight (for example, 5 to 100 parts by weight).

[Polyimide film with adhesive]
In the polyimide film with an adhesive, the thickness of the polyimide film is, for example, 1 to 150 μm (for example, 3 to 125 μm), preferably 5 to 120 μm (for example, 7 to 100 μm), and more preferably 10 to 80 μm (for example, 15 to 50 μm). ).

  In the polyimide film with an adhesive, the thickness of the adhesive layer is not particularly limited, but is preferably at least １ ／ of the thickness of the conductor in consideration of the embedding property of the conductor. In this case, it is preferable from the viewpoint that the conductor is sufficiently embedded and a gap is hardly generated between the conductors. If there is a gap between the conductors, the transmission characteristics and the like of the flat cable are affected, which is not preferable.

The adhesive layer of the polyimide film with an adhesive has a needle penetration amount at 180 ° C. in the TMA needle penetration mode measurement of preferably 40% or more (for example, 45 to 90%) of the thickness of the adhesive layer, More preferably, it may be about 50% or more (for example, 53 to 85%), and still more preferably about 55% or more (for example, 55 to 80%). The method for forming the adhesive layer in which the penetration amount into the needle at 180 ° C. in the TMA needle insertion mode measurement is within the above range is not particularly limited, and can be appropriately adjusted. When the penetration amount into the needle at 180 ° C. is 40% or more, the adhesive layer is soft. Therefore, when the polyimide film with the adhesive is bonded to the conductor and heated, the adhesive melts up to the gap between the conductors, and This is preferable from the viewpoint of easily preventing the generation of bubbles.
The adhesive layer of the polyimide film with an adhesive preferably has a penetration into the needle at 100 ° C. of the TMA needle penetration mode measurement of 5% or less (for example, 1 to 4%).
The adhesive layer of the polyimide film with an adhesive preferably has a needle penetration amount of 20% or more (for example, 20 to 40%) at 140 ° C. in TMA needle penetration mode measurement. If the penetration amount into the needle at 100 ° C. is 5% or less, the oozing of the adhesive can be suppressed, and the conductor at the connection portion of the flat cable is covered with the adhesive and the connection between the conductor and the connector is made. This is preferable from the viewpoint that the occurrence of defects can be prevented. Further, when the penetration amount into the needle at 140 ° C. is 20% or more, the adhesive layer is sufficiently soft, so that when the polyimide film with the adhesive is bonded to the conductor and heated, the adhesive melts between the conductors. However, it is preferable from the viewpoint of easily preventing generation of bubbles between conductors.

The penetration depth into the needle at 180 ° C in the TMA needle penetration mode measurement was measured by using a TMA measuring device to measure the needle penetration mode at a heating rate of 10 ° C / min up to 200 ° C and the penetration depth of the indenter up to 180 ° C. (The amount of needle penetration, unit: μm) can be read and determined by the ratio of the penetration depth of the indenter up to 180 ° C. with respect to the thickness of the adhesive layer. As the TMA measuring device, a thermal analyzer (TMA-60) manufactured by Shimadzu Corporation may be used.
The penetration amount at 100 ° C. in the TMA needle penetration mode measurement and the needle penetration depth at 140 ° C. in the TMA needle penetration mode measurement are the needle penetration at 180 ° C. in the TMA needle penetration mode measurement described above. In the same manner as the measurement of the penetration depth, the needle penetration mode is measured at a heating rate of 10 ° C./min up to 200 ° C., and the penetration depth of the indenter up to 100 ° C. and the penetration depth of the indenter up to 140 ° C. are read. , You can ask.

  The polyimide film with an adhesive can be obtained, for example, by applying an adhesive to one or both sides of the polyimide film and drying. The application and drying methods are not particularly limited.

[Flat cable]
The polyimide film with an adhesive of the present invention can be used for manufacturing a flat cable.
The method for manufacturing the flat cable is not particularly limited, and may be any method as long as the conductor is sandwiched (sandwiched) between two (a pair of) polyimide films with an adhesive. In a flat cable, a conductor is usually sandwiched between adhesive layers of a polyimide film with an adhesive. The flat cable can be manufactured, for example, by sandwiching a conductor row in which a plurality of conductors are arranged in the same plane between adhesive layers of a polyimide film with an adhesive. When the conductor is sandwiched between the polyimide films with the adhesive, heating, pressurization, or the like may be performed.

  Examples of the conductor include, but are not particularly limited to, a flat foil or a round wire of a conductive metal, a rectangular conductor having a rectangular cross section, and an organic conductor. The conductive metal is not particularly limited, but copper, silver, tin, indium, aluminum, molybdenum, an alloy thereof, or the like may be used. Further, the width and thickness of the conductor are not particularly limited.

The flat cable may further have a reinforcing plate.
The reinforcing plate is, for example, a single polyimide film or a laminate of a plurality of (for example, two to three) polyimide films. The method of laminating a plurality of polyimide films is not specified, but there are a method of laminating only the polyimide film and a method of laminating another layer (for example, an adhesive layer) between the polyimide films. The structure and physical properties of the polyimide film in this case are not particularly limited.
The thickness of the reinforcing plate may be, for example, about 50 to 500 μm (for example, 75 to 300 μm).
Further, the reinforcing plate may be laminated on one side of the flat cable, or may be laminated on both sides.

  The flat cable of the present invention has excellent dimensional stability due to heat, and has a heat shrinkage (dimensional change) after heating at 180 ° C. for 10 minutes of, for example, 0.2% or less (for example, 0.01 to 0.15%). ), Preferably 0.15% or less (for example, 0.01 to 0.13%).

  Next, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples at all, and many modifications may be made within the technical concept of the present invention. It is possible by a person having ordinary knowledge.

[Synthesis example of polyamic acid A]
Pyromellitic dianhydride (molecular weight 218.12) / 4,4′-diaminodiphenyl ether (molecular weight 200.24) was prepared at a molar ratio of 1: 1, and was prepared by adding 20 parts in DMAc (N, N-dimethylacetamide). The resulting solution was polymerized in a weight% solution to obtain a 4000 poise polyamic acid solution.

[Polyamic acid synthesis example B]
Pyromellitic dianhydride (molecular weight 218.12) / 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (molecular weight 294.22) / 4,4'-diaminodiphenyl ether (molecular weight 200.24) / Paraphenylenediamine (molecular weight 108.14) was prepared in a molar ratio of 60/40/80/20, and polymerized as a 20% by weight solution in DMAc (N, N-dimethylacetamide) to obtain a polyamic acid of 4000 poise. An acid solution was obtained.

[Thermal shrinkage of polyimide film]
The heat shrinkage of the polyimide film after heating at 200 ° C. for 60 minutes is determined by measuring the film size (L1) of the polyimide film after being left for 2 hours or more in a room adjusted to 25 ° C. and 60% RH, using the CNC image processing system NEXIV VM-. 250 (manufactured by Nikon), followed by heating at 200 ° C. for 60 minutes and then again standing in a room adjusted to 25 ° C. and 60% RH for 1 day to determine the film size (L2) by the CNC image. It was measured using a processing system and calculated by the following equation.
Heat shrinkage (%) =-{(L2-L1) / L1} × 100

[Surface roughness of polyimide film]
The surface roughness of the polyimide film was measured according to JIS B 0601 (2001). The surface roughness Rmax and Rz were measured under the following conditions using a contact type surface roughness measuring device.
Cut-off value: 0.25 mm, measuring length: 2 mm, stylus tip half radius: 2 μm

[Measurement of needle penetration amount]
The polyimide film with the adhesive was cut into a size of 10 mm x 10 mm, and the measurement in the needle-in mode was performed using a thermal analyzer (TMA-60) manufactured by Shimadzu Corporation at a heating rate of 10 ° C / min and a constant load of 50 gf up to 200 ° C. The depth of penetration of the indenter (penetration amount, unit: μm) was read up to 100 ° C., 140 ° C., and 180 ° C. The indenter used was a cylindrical one with a tip diameter of 0.5 mm, and the surface of the adhesive was used as the indenter entry surface.

[Embedding property]
The presence or absence of bubbles between the flat cable conductors was visually checked, and the length of the portion where bubbles were generated was measured. The ratio of the length of the bubble generation location to the length of the flat cable was calculated and defined as the bubble generation rate.

[Thermal shrinkage rate of flat cable (dimensional change rate)]
The produced flat cable is heated at 180 ° C. for 10 minutes, and the conductor dimension before heating (L3) and the conductor dimension after heating (L4) are measured using a CNC image processing system NEXIV VM-250 (manufactured by Nikon). It was measured and calculated according to the following equation.
Heat shrinkage (%) =-{(L4-L3) / L3} × 100

[Formation of polyimide film A]
The particle diameter of all the inorganic particles is 0.01 μm or more and 6.0 μm or less, and particles having an average particle diameter of 0.87 μm and a particle diameter of 0.5 to 2.5 μm account for 81.5% by volume of phosphorus in all the particles. N, N-dimethylacetamide slurry of calcium hydrogen oxyate was added to the polyamic acid solution obtained in Synthesis Example A at 0.15% by weight based on the weight of the resin, and sufficiently stirred and dispersed. A conversion agent consisting of acetic anhydride (molecular weight 102.09) and β-picoline was mixed with the polyamic acid solution at a ratio of 2.0 molar equivalents to the polyamic acid and stirred. The resulting mixture was cast from a die on a rotating stainless steel drum at 65 ° C. to obtain a gel film having self-supporting properties. This gel film was peeled off from the drum, the both ends thereof were gripped, and treated in a heating furnace at 250 ° C. × 30 seconds, 400 ° C. × 30 seconds, and then 550 ° C. × 30 seconds. The obtained film was annealed at 300 ° C. for 1 minute in a heating furnace to obtain a polyimide film having a thickness of 25 μm, Rmax 0.8 μm, and Rz 0.5 μm.

[Formation of polyimide film B]
One surface of the polyimide film A was subjected to a sand mat treatment to obtain a polyimide film B having a thickness of 25 μm, a Rmax of 1.4 μm, and an Rz of 1.0 μm on the sand matte treated surface. The sand mat treatment was performed by hitting particles having a sand particle diameter distribution of 80 to 200 μm on the film surface.

Example 1
[adhesive]
EPICLON HP-7200 (manufactured by DIC Corporation, dicyclopentadiene skeleton-containing epoxy resin) 10 parts by weight, Tuftec M1913 (Asahi Kasei Chemicals Corporation, maleic acid-modified styrene ethylene block copolymer) 100 parts by weight, Cureazole C11-Z (Shikoku) 0.3 parts by weight (manufactured by Kasei Co., Ltd.) and 420 parts by weight of toluene were mixed to prepare an adhesive.

[Polyimide film with adhesive]
The above-mentioned adhesive was applied to one surface of the polyimide film A obtained above, and dried at 90 ° C. for 3 minutes to obtain a polyimide film with an adhesive. In the polyimide film with an adhesive, the thickness of the adhesive layer was 25 μm.

[Preparation of flat cable sample]
Fourteen conductors having a width of 0.30 mm and a thickness of 0.035 mm are arranged on the adhesive layer side of the polyimide film with an adhesive at a pitch of 0.50 mm between the conductors, and another polyimide film with an adhesive is further placed thereon. A flat cable was manufactured by applying a pressure of 180 ° C. and 0.5 MPa with a hot roll at a temperature of 180 ° C.

Example 2
A flat cable was produced in the same manner as in Example 1 except that a polyimide film B was used instead of the polyimide film A, and an adhesive was applied to the sand matted surface of the polyimide film B.

Example 3
In the adhesive, jER828 (manufactured by Mitsubishi Chemical Corporation, bisphenol A type epoxy resin) is used instead of EPICLON HP-7200, and TD773 (novolak type phenol resin manufactured by DIC Corporation) is used instead of Tuftec M1913. A flat cable was produced in the same manner as in Example 1 except that the thickness of the adhesive layer was 20 μm.

Example 4
In the adhesive, YDCN-700-3 (cresol novolak epoxy resin, manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.) was used instead of EPICLON HP-7200, and Nipol 1072J (manufactured by Zeon Corporation, carboxyl-containing acrylonitrile, instead of Tuftec M1913). Flat cable was produced in the same manner as in Example 1 except that butadiene rubber) was used and the thickness of the polyimide film was adjusted to 12.5 μm.

Example 5
A flat cable was prepared in the same manner as in Example 1 except that an adhesive was applied to the surface of the polyimide film B which had not been subjected to the sand mat treatment instead of the polyimide film A.

Example 6
A flat cable was prepared in the same manner as in Example 3 except that an adhesive was applied to the surface of the polyimide film B which had not been subjected to the sand matting instead of the polyimide film A.

Example 7
A flat cable was prepared in the same manner as in Example 4, except that an adhesive was applied to the surface of the polyimide film B which had not been subjected to the sand mat treatment instead of the polyimide film A.

Comparative Example 1
A flat cable was manufactured in the same manner as in Example 1 except that the polyimide film was not annealed.

Comparative Example 2
A flat cable was manufactured in the same manner as in Example 1 except that the drying conditions for applying the adhesive to one surface of the polyimide film and drying were set at 130 ° C. for 10 minutes.

  Table 1 shows the physical properties of the polyimide film and the flat cable obtained in each of Examples and Comparative Examples.

  When the polyimide film with an adhesive of Examples 1 to 7 was used as a base material for a flat cable, the heat shrinkage (dimensional change) of the flat cable at 180 ° C. was as small as 0.1% or less, and bubbles between conductors were used. Was less likely to occur.

On the other hand, the polyimide film with an adhesive of Comparative Example 1 had a heat shrinkage after heating at 200 ° C. for 60 minutes of more than 0.2% of the used polyimide film. The thermal contraction rate (dimensional change rate) of the flat cable increased to 0.52%.
In the polyimide film with an adhesive of Comparative Example 2, since the penetration amount of the adhesive layer at 180 ° C. of the adhesive layer of the polyimide film with the adhesive at 180 ° C. measured by the TMA needle mode was as small as 28%, the polyimide film with the adhesive was Even when heating was performed when bonding the resin to the conductor, the adhesive did not melt to between the conductors, and the generation of bubbles between the conductors increased.

  From the above results, the polyimide film with the adhesive of the present invention has a heat shrinkage of 0.2% or less after heating at 200 ° C. for 60 minutes of the polyimide film to be used, and the adhesive layer of the polyimide film with the adhesive is used. When the penetration into the needle at 180 ° C. in the TMA needle penetration mode measurement at 40 ° C. is 40% or more, when the flat cable is used for manufacturing a flat cable, the thermal contraction rate (dimensional change rate) of the obtained flat cable becomes small. It was confirmed that the generation of bubbles between conductors in the flat cable could be reduced.

  The polyimide film with an adhesive of the present invention can be suitably used in the production of a flat cable.

Claims (7)

The adhesive layer has a polyimide film having a heat shrinkage of 0.2% or less after heating at 200 ° C. for 60 minutes and an adhesive layer. A polyimide film with an adhesive having a thickness of 40% or more of the layer and used for manufacturing a flat cable .   The amount of penetration of the adhesive layer into the needle with respect to the thickness of the adhesive layer in the TMA needle penetration mode measurement is such that the penetration amount of the needle at 100 ° C. is 5% or less, and the penetration amount of the needle at 140 ° C. Is 20% or more.   The polyimide film with an adhesive according to claim 1 or 2, wherein Rmax of the surface roughness of the polyimide film is 0.6 µm or more, and Rz is 0.3 µm or more.   The polyimide film comprises one or more aromatic diamine components selected from the group consisting of paraphenylenediamine, 4,4′-diaminodiphenyl ether and 3,4′-diaminodiphenyl ether, and pyromellitic dianhydride and / or 3,3 The polyimide film with an adhesive according to any one of claims 1 to 3, wherein the raw material contains an aromatic acid anhydride component of ', 4,4'-biphenyltetracarboxylic dianhydride.   The polyimide film with an adhesive according to any one of claims 1 to 4, wherein the adhesive layer includes an adhesive component containing an epoxy resin and an additive containing another resin. A flat cable in which a conductor is sandwiched between a pair of the polyimide films with an adhesive according to any one of claims 1 to 5 . The flat cable according to claim 6 , further comprising a polyimide film having a thickness of 50 to 500 μm or a reinforcing plate formed by laminating a plurality of polyimide films.