JP6802131B2 - Polyimide film with adhesive - Google Patents

Description

The present invention is a polyimide film with an adhesive, which is useful for manufacturing a flat cable manufactured by sandwiching a conductor between two base materials having an adhesive layer and an insulator layer, and a polyimide film with an adhesive. Regarding the configured flat cable.

Flat cables are widely used in electrical equipment such as televisions, mobile phones and tablets, and hard disks for personal computers. In a flat cable, conductors such as copper foil formed in a wiring shape are arranged between a base material having an insulator layer and an adhesive layer (or simply referred to as a "base material for a flat cable"), and the base material is used. It is manufactured by sandwiching it between the adhesive layers of.

High flame retardancy is required for such flat cables, and techniques for improving the flame retardancy of flat cables are being developed.

In Patent Document 1, a flat cable formed by sandwiching a plurality of conductors in parallel with each adhesive layer inside between two insulating substrates having an insulating film layer and an adhesive layer, and heat-sealing them. In the above, the insulating film layer of the insulating base material is a film formed of an aromatic polymer (polyimide, etc.) having an aromatic ring in the molecular skeleton, containing no halogen, and having a critical oxygen index of 30% or more. Further, a non-halogen flame-retardant flat cable comprising a composition in which the adhesive layer contains 50 to 200 parts by weight of metal hydrate with respect to 100 parts by weight of the base polymer and does not contain a halide is disclosed.

Japanese Unexamined Patent Publication No. 5-217430

An object of the present invention is to provide a polyimide film (base material) with an adhesive having excellent flame retardancy and a flat cable composed of the polyimide film.

Another object of the present invention is to provide a polyimide film with an adhesive having excellent heat resistance (furthermore, dimensional stability due to heat) and a flat cable made of the polyimide film.

Still another object of the present invention is to provide a polyimide film with an adhesive capable of efficiently suppressing or preventing the generation of air bubbles, and a flat cable made of the polyimide film.

Among the base films used for flat cables, the present inventors have focused on the polyimide film and investigated a further flame retardant method for the polyimide film provided with an adhesive layer, but the flame retardant and the flame retardant aid have been investigated. It has been difficult to improve the flame retardancy without using (for example, the metal hydrate of Patent Document 1).

Under these circumstances, as a result of further diligent studies, the present inventors have selected the formulation and treatment of the polyimide film for the polyimide film and the adhesive layer, and needle-inserted in the TMA needle-insertion mode measurement of the adhesive layer. By adjusting the amount of penetration and adjusting the thickness ratio of the polyimide film and the adhesive layer, even though the adhesive layer is provided, the adhesive layer is substantially filled with flame retardant and flame retardant aid. A polyimide film with an adhesive having a high oxygen index (that is, high flame retardancy) can be obtained even if it is not used in the above (even if it is non-halogen type), and further, such a polyimide film with an adhesive Found that it is excellent in heat resistance and dimensional stability due to heat.

Further, when a conductor is sandwiched between flat cable base materials and heated to form a flat cable, especially when a thermosetting resin (for example, epoxy resin) is used for the adhesive layer of the flat cable base material, it is flat. Although gaps are likely to occur between the conductors of the cable, the present inventors have defined the adhesive layer so that the amount of needle penetration in the TMA needle insertion mode measurement is within a specific range, so that the gap between the conductors of the flat cable is likely to occur. It was found that voids are unlikely to occur in the water.
Further research was carried out based on these findings, and the present invention was completed.

The present invention relates to the following polyimide films with adhesives and the like.
[1] A polyimide film with an adhesive having an oxygen index of 30% or more.
[2] The polyimide film with an adhesive according to [1], wherein the thickness of the adhesive layer is 0.25 to 2.3 times the thickness of the polyimide film.
[3] The amount of needle penetration at 100 ° C. of the TMA needle-entry mode measurement of the adhesive layer is 10% or less of the thickness of the adhesive layer, and / or at 140 ° C. of the TMA needle-entry mode measurement of the adhesive layer. The polyimide film with an adhesive according to [1] or [2], wherein the amount of penetration into the needle is 20% or more of the thickness of the adhesive layer.
[4] The polyimide with adhesive according to any one of [1] to [3], wherein the amount of needle penetration at 180 ° C. in the TMA needle insertion mode measurement of the adhesive layer is 40% or more of the thickness of the adhesive layer. the film.
[5] The polyimide film contains 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 [1] to [4], which contains an aromatic acid anhydride component of 3,3', 4,4'-biphenyltetracarboxylic dianhydride as a raw material.
[6] The polyimide film with an adhesive according to any one of [1] to [5], wherein the adhesive layer contains an adhesive component containing an epoxy resin and an additive containing another resin.
[7] The polyimide film with an adhesive according to any one of [1] to [6], wherein the adhesive layer does not substantially contain a flame retardant.
[8] The polyimide film with an adhesive according to any one of [1] to [7] for use in manufacturing a flat cable.
[9] A flat cable in which a conductor is sandwiched between a pair of polyimide films with an adhesive according to any one of [1] to [8].

The polyimide film (polyimide film with an adhesive) of the present invention is excellent in flame retardancy even though it has an adhesive layer. In particular, such a polyimide film is highly difficult even if the adhesive layer does not substantially contain a flame retardant or a flame retardant aid (for example, a metal hydrate, an antimony compound, a halogen compound, etc.). Shows flammability. In addition, excellent flame retardancy can be realized even if it does not contain halogen. Therefore, the polyimide film with an adhesive can be made flame-retardant with no halogen (halogen-free) without impairing physical properties such as dielectric constant, and is extremely useful.

Further, the polyimide film with an adhesive of the present invention is excellent in heat resistance and dimensional stability due to heat. Therefore, for example, it can be efficiently used even at a high temperature (for example, 180 ° C. or higher) that cannot be used with a PET film or the like.

Further, the polyimide film with an adhesive of the present invention can efficiently suppress or prevent the generation of air bubbles. Therefore, for example, an effect such as being able to efficiently suppress or prevent voids generated between conductors can be obtained.

As described above, the polyimide film with an adhesive of the present invention has the above-mentioned excellent properties, and particularly when used for a flat cable (base material for a flat cable), a high-performance flat cable can be obtained. Can be done.
As the flat cable, for example, it may be used for various electric devices (for example, a television, a mobile phone, a tablet, a personal computer), and in particular, it may be used for an FPD (flat panel display).

Hereinafter, the present invention will be described in more detail.
The polyimide film with an adhesive of the present invention is a polyimide film provided with an adhesive layer and has a specific oxygen index. Such a polyimide film with an adhesive usually has an adhesive layer on one side of the polyimide film. The polyimide film with an adhesive may be further provided with another layer on the polyimide film surface (the surface of the polyimide film on which the adhesive layer is not provided).

[Polyimide film]
When obtaining a polyimide film, first, a polyamic acid solution (hereinafter, also referred to as a polyamic acid solution) is obtained by polymerizing an aromatic diamine component and an aromatic acid anhydride component in an organic solvent.
The polyamic acid solution can be obtained by polymerizing a chemical substance containing 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, paraxylylene diamine, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, 4, 4'-diaminodiphenylsulfone, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, 1,5-diaminonaphthalene, 3,3'-dimethoxybenzidine, 1,4-bis (3-methyl-5-amino) Examples include phenyl) benzene and amide-forming derivatives thereof. These may be used individually by 1 type, or may be used by mixing 2 or more types.

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

The raw material used for forming the polyamic acid solution may contain a diamine component other than the aromatic diamine component as long as the effect of the present invention is 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) Aminophenyl) phenylphosphinoxide, bis- (4-aminophenyl) -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-xylylene diamine, p-xylylene diamine, 1,3-diaminoadamantan, 3,3'-diamino-1,1'-diaminoadamantan, 3,3'-diaminomethyl-1,1'-diadamantan, 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 −Aminophenyl) -4-aminobenzamide, 4-aminophenyl-3-aminobenzoate and the like can be mentioned. These may be used individually by 1 type, or may be used by mixing 2 or more types.

Specific examples of the aromatic acid anhydride component include pyromellitic acid, 3,3', 4,4'-biphenyltetracarboxylic acid, 2,3', 3,4'-biphenyltetracarboxylic acid, 3, 3', 4,4'-benzophenone tetracarboxylic acid, 2,3,6,7-naphthalene tetracarboxylic acid, 2,2-bis (3,4-dicarboxyphenyl) ether, pyridine-2,3,5 Examples thereof include acid anhydride components of aromatic tetracarboxylic acids such as 6-tetracarboxylic acid and amide-forming derivatives thereof. These may be used individually by 1 type, or may be used by mixing 2 or more types.

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

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 effect of the present invention is not impaired.
Examples of other acid anhydride components include 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 Tetetracarboxylic dianhydride, 2,7-dichloro-1,4,5,8-naphthalenetetracarboxylic dianhydride, 2,3,6,7-tetrachloro-1,4,5,8-naphthalenetetra Carcarboxylic dianhydride, 1,8,9,10-phenanthrenetetracarboxylic dianhydride, 2,2-bis (2,3-dicarboxyphenyl) propanedianhydride, 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) sulfonate dianhydride, benzene-1,2,3,4-tetracarboxylic dianhydride, 3,4,3', 4' -Benzophenone tetracarboxylic dianhydride and the like can be mentioned. These may be used alone or in combination of two or more.

The aromatic diamine component and / or the aromatic acid anhydride component may be a non-halogen component (a halogen-free component).

In the present invention, the combination of the aromatic diamine component and the acid anhydride component is one or more aromatic diamine components selected from the group consisting of paraphenylenediamine, 4,4'-diaminodiphenyl ether and 3,4'-diaminodiphenyl ether. And / or the combination of the aromatic acid anhydride component of the pyromellitic dianhydride and / or the 3,3', 4,4'-biphenyltetracarboxylic dianhydride is particularly preferable.

When the aromatic diamine component contains paraphenylenediamine and 4,4'-diaminodiphenyl ether, the molar ratio of paraphenylenediamine to 4,4'-diaminodiphenyl ether is preferably 50/50 to 0/100, 40. More preferably, it is / 60 to 0/100.

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 100/0 to 50/50, more preferably 100/0 to 60/40.

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

The method for polymerizing the polyamic acid solution may be any known method, for example.
(1) A method in which the entire amount of the aromatic diamine component is first placed in a solvent, and then the aromatic acid anhydride component is added so as to be equivalent to the total amount of the aromatic diamine component for polymerization.
(2) A method in which the entire amount of the aromatic acid anhydride component is first placed in a solvent, and then the aromatic diamine component is added so as to be equivalent to the aromatic acid anhydride component for polymerization.
(3) After putting one aromatic diamine component in the solvent and mixing the one aromatic acid anhydride component at a ratio of 95 to 105 mol% with respect to the reaction component for the time required for the reaction, then another A method of adding one aromatic diamine component and then adding the other aromatic acid anhydride component so that the total aromatic diamine component and the total aromatic acid anhydride component are approximately equivalent to each other for polymerization.
(4) After putting one aromatic acid anhydride component in a solvent and mixing the one aromatic diamine component at a ratio of 95 to 105 mol% with respect to the reaction component for the time required for the reaction, then another A method in which one aromatic acid anhydride component is added, and then the other aromatic diamine component is added so that the total aromatic diamine component and the total aromatic acid anhydride component are approximately equivalent amounts to polymerize.
(5) One aromatic diamine component and an aromatic acid anhydride component are reacted in a solvent so that one of them becomes excessive to prepare a polyamic acid solution (A), and the other aromatic component is prepared in another solvent. The polyamic acid solution (B) is prepared by reacting the diamine component and the aromatic acid anhydride component so that either of them becomes excessive. A method of mixing each of the polyamic acid solutions (A) and (B) thus obtained to complete the polymerization. At this time, if the aromatic diamine component is excessive when preparing the polyamic acid solution (A), the aromatic acid anhydride component is excessive in the polyamic acid solution (B), and the aromatic acid anhydride is added in the polyamic acid solution (A). When the physical component is excessive, the aromatic diamine component is excessive in the polyamic acid solution (B), the polyamic acid solutions (A) and (B) are mixed, and the total aromatic diamine component and the total aromatic used in these reactions are mixed. Examples thereof include a method of adjusting the amount of the acid anhydride component to be substantially equal to that of the acid anhydride component.
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 at a ratio in which the number of moles of each is approximately equal, but one of them is 10 mol%, preferably 5 mol%. It may be overblown with respect to the other within the range.

The polymerization reaction is preferably carried out in an organic solvent with stirring. The polymerization temperature is not particularly limited, but 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 it is preferably carried out continuously for 10 minutes to 30 hours. In the polymerization reaction, the polymerization reaction may be divided or the temperature may be raised or lowered, if necessary. 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 defoaming during the polymerization reaction is an effective method for producing good quality organic solvent solutions of polyamic acids. Further, the polymerization reaction may be controlled by adding a small amount of end-capping agent to the aromatic diamines before the polymerization reaction. The end-capping agent is not particularly limited, and known ones can be used.

The polyamic acid solution thus obtained contains a solid content of usually 5 to 40% by weight, preferably 10 to 30% by weight. 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), preferably 100 to 1000 Pa · s for stable liquid delivery. (1000 to 10000 points). The polyamic acid in the organic solvent solution may be partially imidized.

A polyimide film can be produced by heating the polyamic acid solution.
Examples of the method for producing a polyimide film include a method of casting a polyamic acid solution into a film and thermally decyclizing and desolving it to obtain a polyimide film, and a method of mixing a cyclization catalyst and a dehydrating agent with a polyamic acid solution and chemistry. A method of obtaining a polyimide film by subjecting it to decyclization to prepare a gel film and heat-desolventing the gel film can be mentioned, but the latter is preferable.

In the method of chemically decyclizing, the above polyamic acid solution is first prepared. The polyamic acid solution can contain a cyclization catalyst (imidization catalyst), a dehydrating agent, a gelation 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 isoquinolin, pyridine, and β-picoline. These can be used alone or in combination of two or more. Among them, it is preferable to use at least one heterocyclic tertiary amine.

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

As a method for producing a polyimide film from a polyamic acid solution, for example, a polyamic acid solution containing a cyclization catalyst and a dehydrating agent is poured onto a support from a mouthpiece with a slit or the like to form a film, and the support is formed. A method of obtaining a polyimide film by partially advancing imidization to obtain a gel film having self-supporting property and then peeling from the support and performing heat treatment can be mentioned.

The polyamic acid solution is cast on a heated support, undergoes a ring closure reaction on the support, becomes a self-supporting gel film, and is peeled off from the support.

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

The gel film is usually heated to 30 to 200 ° C., preferably 40 to 150 ° C. by receiving heat from a support and / or heat from a heat source such as hot air or an electric heater, and undergoes a ring closure reaction to release an organic solvent or the like. By drying the volatile matter of, it becomes self-supporting and is peeled off from the support.

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

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

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 thickness of the target laminated film, the number of polyimide films to be used, and the like.

It is preferable that the polyimide film thus obtained is further annealed. By the annealing treatment, it is easy to efficiently reduce the heat shrinkage rate (specifically, for example, the heat shrinkage rate after heating at 200 ° C. for 60 minutes can be set to 0.2% or less). The method of annealing is not particularly limited, and a conventional method may be followed. 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 to run the film under low tension in a furnace heated to the above temperature range to perform annealing treatment. The processing time is the time that the film stays in the furnace, but it is controlled by changing the traveling speed, and the processing time is preferably 5 seconds to 5 minutes. The film tension during running is preferably 10 to 50 N / m, more preferably 20 to 30 N / m.

The polyimide film may contain a filler (for example, inorganic particles, an organic filler, etc.), and preferably contains inorganic particles.
The content of the filler in the polyimide film is not particularly limited, but may be, for example, 0.03 to 1% by weight, preferably about 0.05 to 0.8% by weight.

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

In the polyimide film, the heat shrinkage rate after heating at 200 ° C. for 60 minutes is not particularly limited, but is, for example, 0.2% or less (for example, 0.01 to 0.15%), preferably 0.15% or less (for example, 0.01 to 0.15%). For example, it may be 0.01 to 0.1%), more preferably 0.1% or less (for example, 0.01 to 0.07%). By using such a polyimide film, the heat shrinkage rate of the polyimide film with an adhesive can be easily reduced efficiently.
The heat shrinkage rate of the polyimide film after heating at 200 ° C. for 60 minutes is the film size (L1) after being left in a room adjusted to 25 ° C. and 60% RH for 2 hours or more, and the CNC image processing device system NEXIV VM- The film size (L2) after being measured using 250 (manufactured by Nikon), subsequently heated at 200 ° C. for 60 minutes, and then left in a room adjusted to 25 ° C. and 60% RH for 1 day, is shown in the CNC image. It can be measured using a processing device system and calculated by the following formula.
Heat shrinkage rate (%) =-{(L2-L1) / L1} × 100

The average coefficient of linear expansion of the polyimide film is not particularly limited, but may be, for example, 0 to 100 ppm / ° C., preferably 0 to 50 ppm / ° C., and more preferably 3 to 35 ppm / ° C. The coefficient of thermal expansion can be measured using a TMA-50 manufactured by Shimadzu Corporation under the conditions of a measurement temperature range of 50 to 200 ° C. and a heating rate of 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) from the viewpoint of improving the adhesiveness of the adhesive layer or the reinforcing plate to be bonded to the opposite surface of the adhesive layer. It may be about 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 adhesiveness with the adhesive layer. The surface roughness of the polyimide film may be measured according to JIS B 0601 (2001).
The method for obtaining a polyimide film having such a surface roughness is not particularly limited, but can be obtained by, for example, a known surface treatment (for example, wet blast treatment, sand mat treatment, resin mat treatment, plasma treatment, etc.). it can. The surface treatment may be one side or both sides of the polyimide film.

In the polyimide film with an adhesive, the polyimide film may be a substantially non-halogen-based polyimide film (a polyimide film containing no halogen), and is substantially a flame retardant (similar to the adhesive layer described later). It may be a polyimide film containing no flame retardant aid).

[Adhesive layer]
The adhesive is not particularly limited as long as it can form an adhesive layer, but usually contains an adhesive component.
Examples of the adhesive component include a thermoplastic resin (for example, a polyamide resin) and a thermosetting resin (for example, an unsaturated polyester resin and an epoxy resin), and a thermosetting resin is preferable.

The adhesive layer may contain additives as long as the adhesiveness is not impaired. As the additive, for example, a resin not included in the category of flame retardant (or flame retardant aid), antioxidant, cross-linking agent, and adhesive component {hereinafter, also simply referred to as "other resin". For example, an elastomer (for example, a styrene-based elastomer)} and the like can be mentioned.
In particular, the adhesive layer may contain a flame retardant (including a flame retardant aid), but may not substantially contain a flame retardant. In the present invention, excellent flame retardancy can be exhibited even if the adhesive layer does not substantially contain a flame retardant.

Flame retardants (including flame retardants) include general-purpose components such as metal hydrates [eg, metal hydroxides (eg magnesium hydroxide, aluminum hydroxide, calcium hydroxide, barium hydroxide, etc.). , Tin oxide hydrate, basic magnesium carbonate, etc.], Halogen compounds {For example, halogen-containing low molecular weight compounds (decabromodiphenyl ether, halogenated bisphenol A, etc.), halogen-containing resins [for example, epoxy resin (bromineed epoxy resin) Etc.] etc.}, antimony compounds (eg, antimony trioxide, etc.), phosphorus compounds (eg, phosphorus-containing oligomers, ammonium phosphate, aluminum trisdiphenylphosphite, etc.) and the like.

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

In the adhesive layer, the additive (particularly, the additive that is not a flame retardant) is, for example, 1.5 to 200 parts by weight (for example, 2 to 170 parts by weight), preferably 2 to 2 parts by weight, based on 1 part by weight of the adhesive component. It may be about 150 parts by weight (for example, 3 to 140 parts by weight), more preferably about 3 to 120 parts by weight (for example, 5 to 100 parts by weight).

In particular, with respect to the flame retardant, even when the adhesive layer contains the flame retardant, it is preferable that the adhesive layer is substantially not contained, and the proportion of the flame retardant is, for example, a component (solid content) of the adhesive layer. ) 20% by weight or less, preferably 10% by weight or less, more preferably 5% by weight or less, and particularly preferably 3% by weight or less, based on the whole.

Further, the adhesive layer may be substantially non-halogen (halogen-free, halogen-free).

[Polyimide film with adhesive]
In the polyimide film with an adhesive, the thickness (average 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, it may be about 15 to 50 μm).

In the polyimide film with an adhesive, the thickness (average thickness) of the adhesive layer is not particularly limited, but is, for example, 300 μm or less (for example, 1 to 250 μm), preferably 200 μm or less (for example, 2 to 180 μm), and further. It may be preferably 150 μm or less (for example, 3 to 120 μm), particularly 100 μm or less (for example, 5 to 80 μm), and is usually 1 to 50 μm (for example, 3 to 40 μm, preferably 5 to 35 μm, more preferably 10 to 10 μm). It may be 30 μm).

In particular, the thickness (average thickness) of the adhesive layer is preferably not too large with respect to the total thickness of the polyimide film with adhesive. For example, a polyimide film (polyimide film without an adhesive layer). ) Can be selected from the range of 3 times or less (for example, 0.01 to 2.8 times), for example, 2.5 times or less (for example, 0.05 to 2.). 4 times or less, preferably 2.3 times or less (for example, 0.1 to 2.2 times), more preferably 2 times or less (for example, 0.15 to 1.8 times), particularly 1.5 times or less (for example, 1.5 times or less). For example, it may be 0.2 to 1.2 times), and usually 0.25 to 2.3 times.

By adjusting the thickness of the adhesive layer as described above, it is easy to obtain a polyimide film with an adhesive having excellent flame retardancy.

Further, the thickness (average thickness) of the adhesive layer may be ½ or more 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 conductors are sufficiently embedded and voids are less likely to be generated between the conductors.

The polyimide film with an adhesive of the present invention has excellent flame retardancy.
For example, the oxygen index of the polyimide film with an adhesive of the present invention can be selected from the range of 25% or more (for example, 27 to 90%), for example, 30% or more (for example, 32 to 80%), preferably 35%. It may be more than (for example, 37 to 75%), more preferably 40% or more (for example, 42 to 70%), and particularly 45% or more (for example, 46 to 65%).

The oxygen index can be measured according to, for example, JIS K7201-2.

The adhesive layer of the polyimide film with an adhesive may adjust the amount of needle penetration in the TMA needle insertion mode measurement to a specific range.

For example, the adhesive layer of the polyimide film with adhesive has a needle penetration amount (penetration ratio) of 10% or less (for example, 0 to 8%) at 100 ° C. with respect to the thickness of the adhesive layer in the TMA needle insertion mode measurement. ), preferably 7% or less (for example, 0.1 to 6%), more preferably 6% or less (for example, 0.3 to 5.5%), particularly 5% or less (for example, 0.5 to 5%). ) May be satisfied.

The needle penetration amount (penetration ratio) with respect to the thickness of the adhesive layer is (B / A) × 100 (%) when the thickness of the adhesive layer is A (μm) and the needle penetration amount is B (μm). ) Can be expressed.

Further, the adhesive layer of the polyimide film with adhesive has a needle penetration amount (penetration ratio) of 5% or more (for example, 7 to 90%) at 140 ° C. with respect to the thickness of the adhesive layer in the TMA needle insertion mode measurement. ), For example, 10% or more (for example, 15 to 88%), preferably 20% or more (for example, 20 to 85%), and more preferably 25% or more (for example, 26 to 80%). It may be satisfied.

The adhesive layer of the polyimide film with adhesive has a needle penetration amount (penetration ratio) of 20% or more (for example, 22 to 95%) at 180 ° C. with respect to the thickness of the adhesive layer in the TMA needle insertion mode measurement. It can be selected from the range, for example, 25% or more (for example, 27 to 92%), preferably 30% or more (for example, 35 to 90%), more preferably 40% or more (for example, 42 to 88%), particularly 45. % Or more (for example, 50 to 85%) may be satisfied.

By adjusting the intrusion of needles at each temperature as described above, it is easy to efficiently adjust flame retardancy, heat resistance, dimensional stability, amount of air bubbles generated between conductors, and the like.

The amount of needle penetration at each temperature (100 ° C, 140 ° C, 180 ° C) of the TMA needle-insertion mode measurement can be measured up to 200 ° C at a temperature rise rate of 10 ° C / min using a TMA measuring device. Then, read the indenter penetration depth (needle insertion amount, unit: μm) up to each temperature (100 ° C, 140 ° C, 180 ° C), and read each temperature (100 ° C, 140 ° C, 180 ° C) with respect to the thickness of the adhesive layer. It can be obtained by the ratio of the penetration depth of the indenter. As the TMA measuring device, a thermal analyzer (TMA-60) manufactured by Shimadzu Corporation may be used.

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 it. The coating and drying methods are not particularly limited.

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

The conductor is not particularly limited, and examples thereof include a flat foil and a round wire of a conductive metal, a flat conductor having a rectangular cross section, and an organic conductor. The conductive metal is not particularly limited, but copper, silver, tin, indium, aluminum, molybdenum, alloys thereof and 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 simple substance of a polyimide film or a laminate of a plurality of (for example, 2 to 3) polyimide films. Although the method of laminating a plurality of polyimide films is not specified, there are a method of laminating only the polyimide film and a method of laminating between the polyimide films via another layer (for example, an adhesive layer). 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 the heat shrinkage rate (dimensional change rate) after heating at 180 ° C. for 10 minutes is, 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 in more detail with reference to examples, but the present invention is not limited to these examples, and many modifications are made in the art within the technical idea of the present invention. It is possible by a person with ordinary knowledge.

[Polyamic Acid Synthesis Example A]
Pyromellitic acid dianhydride (molecular weight 218.12) / 4,4'-diaminodiphenyl ether (molecular weight 200.24) was prepared in a molar ratio of 1: 1 and 20 in DMAc (N, N-dimethylacetamide). The solution was made into a weight% solution and polymerized to obtain a polyamic acid solution of 4000 poise.

[Polyamic Acid Synthesis Example B]
Pyromellitic acid dianhydride (molecular weight 218.12) / 3,3', 4,4'-biphenyltetracarboxylic acid 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 in a 20% by weight solution in DMAc (N, N-dimethylacetamide) to form a polyamic of 4000 poise. An acid solution was obtained.

[Oxygen index measurement]
Measured according to JIS K7201-2. A polyimide film with an adhesive was cut into a size of 150 mm x 20 mm and burned using an oxygen index type flammability tester manufactured by Suga Test Instruments Co., Ltd.

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

[Surface roughness of polyimide film]
The surface roughness of the polyimide film was measured according to JIS B 0601 (2001). 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, measurement length: 2 mm, needle tip half radius: 2 μm

[Intrusion rate with needle]
A polyimide film with an adhesive is cut into a size of 10 mm x 10 mm, and a constant load of 50 gf is applied to 200 ° C at a temperature rise rate of 10 ° C / min using a thermal analyzer (TMA-60) manufactured by Shimadzu Corporation. The indenter penetration depth (needle insertion amount, unit: μm) was read up to 100 ° C., 140 ° C., and 180 ° C. Then, the ratio to the thickness of the adhesive layer was calculated from the read numerical value.
The indenter used was a columnar one with a tip diameter of 0.5 mm, and the surface of the adhesive was used as the indenter intrusion surface.

[Embedability]
The presence or absence of air bubbles between the flat cable conductors was visually confirmed, and the length of the place where air 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 used as the bubble generation rate.

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

[Film formation of polyimide film A]
The particle size of all the inorganic particles is 0.01 μm or more and 6.0 μm or less, and the average particle size of 0.87 μm and the particle size of 0.5 to 2.5 μm are 81.5% by volume of phosphorus in the total particles. An N, N-dimethylacetamide slurry of calcium hydrogen acid was added to the polyamic acid solution obtained in Synthesis Example A in an amount of 0.15% by volume based on the weight of the resin, and the mixture was sufficiently stirred and dispersed. A conversion agent composed 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 and stirred. The obtained mixture was cast from a mouthpiece onto a rotating stainless steel drum at 65 ° C. to obtain a self-supporting gel film. The gel film was peeled off from the drum, both ends thereof were grasped, and the gel film was treated in a heating furnace at 250 ° C. × 30 seconds, 400 ° C. × 30 seconds, and then at 550 ° C. × 30 seconds. The obtained film was annealed in a heating furnace at 300 ° C. for 1 minute to obtain a polyimide film having a thickness of 25 μm, Rmax of 0.8 μm, and Rz of 0.5 μm.

[Film formation of polyimide film B]
One side of the polyimide film A was sandmatted to obtain a polyimide film B having a thickness of 25 μm, a sandmatted surface having a Rmax of 1.4 μm and an Rz of 1.0 μm. The sand mat treatment was performed by striking particles having a sand diameter of 80 to 200 μm with a sand particle size distribution onto the film surface.

[Film formation of polyimide film C]
In the film formation of the polyimide film A, the polyimide film C was prepared in the same manner except that the polyamic acid solution obtained in Synthesis Example B was used instead of the polyamic acid solution obtained in Synthesis Example A. The thickness of the obtained polyimide film C was 25 μm, Rmax was 0.8 μm, and Rz was 0.5 μm.

Example 1
[adhesive]
EPICLON HP-7200 (manufactured by DIC Corporation, dicyclopentadiene skeleton-containing epoxy resin) 10 parts by weight, Tough Tech M1913 (Asahi Kasei Chemicals Co., Ltd., maleic acid-modified styrene ethylene block copolymer) 100 parts by weight, Curesol C11-Z (Shikoku) (Manufactured by Kasei Co., Ltd.) 0.3 parts by weight 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 side 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]
51 conductors with 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 adhesive at a pitch between conductors of 0.50 mm, and another polyimide with adhesive is placed on top of it. A flat cable was produced by having a structure in which the adhesive layer side of the film was overlapped and pressurized at 180 ° C. and 0.5 MPa with a thermal roll.

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

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

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

Example 5
A flat cable was produced in the same manner as in Example 1 except that the drying conditions for applying the adhesive to one side of the polyimide film and drying were set to 130 ° C. for 10 minutes.

Example 6
A polyimide film with an adhesive and a flat cable were produced in the same manner as in Example 1 except that the polyimide film C was used instead of the polyimide film A.

Reference example 1
A flat cable was produced in the same manner as in Example 1 except that the thickness of the adhesive layer was 60 μm.

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

The polyimide film with adhesive of the example had a large oxygen index of at least 37%. In addition, the heat shrinkage rate (dimensional change rate) at 180 ° C. could be as small as 0.08% at the maximum. Further, in Examples 1 to 4 and 6, the generation of air bubbles between the conductors can be reduced.

On the other hand, the polyimide film with an adhesive of Reference Example 1 had a low flame retardancy with an oxygen index of 20%.

The polyimide film with an adhesive of the present invention has excellent flame retardancy and can be suitably used for flat cables and the like.

Claims (9)

Der oxygen index more than 30% is, the needle entering penetration amount at 180 ° C. of TMA needle print mode measurement of the adhesive layer is at least 40% of the thickness of the adhesive layer, for use in the manufacture of flat cable, Polyimide film with adhesive. The polyimide film with an adhesive according to claim 1, wherein the thickness of the adhesive layer is 0.25 to 2.3 times the thickness of the polyimide film. The amount of needle penetration at 100 ° C. in the TMA needle mode measurement of the adhesive layer is 10% or less of the thickness of the adhesive layer and / or the needle penetration at 140 ° C. in the TMA needle mode measurement of the adhesive layer. The polyimide film with an adhesive according to claim 1 or 2, wherein the amount is 20% or more of the thickness of the adhesive layer. The amount of needle penetration of the adhesive layer in TMA needle mode measurement at 100 ° C is 10% or less of the thickness of the adhesive layer, and the amount of needle penetration in TMA needle mode measurement of the adhesive layer at 140 ° C. The polyimide film with an adhesive according to any one of claims 1 to 3, which is 20% or more of the thickness of the adhesive layer. The polyimide film with an adhesive according to any one of claims 1 to 4 , wherein the amount of needle penetration at 180 ° C. in the TMA needle-entry mode measurement of the adhesive layer is 45 % or more of the thickness of the adhesive layer. 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 anhydride and / or 3,3. The polyimide film with an adhesive according to any one of claims 1 to 5 , which contains an aromatic acid anhydride component of', 4,4'-biphenyltetracarboxylic acid dianhydride as a raw material. The polyimide film with an adhesive according to any one of claims 1 to 6 , wherein the adhesive layer contains an adhesive component containing an epoxy resin and an additive containing another resin. The polyimide film with an adhesive according to any one of claims 1 to 7 , wherein the adhesive layer is substantially free of a flame retardant. A flat cable in which a conductor is sandwiched between a pair of polyimide films with an adhesive according to any one of claims 1 to 8.