JP2012067292A - Adhesive composition, and coverlay film and flexible copper-clad laminate using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adhesive composition which does not deteriorate adhesiveness even when an adherend is placed in high temperature environment for a long time and which exhibits excellent adhesion strength to a polyimide film when used for FPC and is excellent in heat-aging resistance and soldering heat resistance.SOLUTION: The adhesive composition contains a polyurethane resin (A), an epoxy resin (B), a phenol resin (C) having a triazine ring, and a phenoxy resin (D), wherein the polyurethane resin (A) has a melting point of 30-150°C. The epoxy resin (B) is preferably a mixture of a resin (b1) having two epoxy groups per molecule and a polyfunctional epoxy resin (b2).

Description

  The present invention relates to an adhesive composition, and particularly to an adhesive composition that can be preferably used as an adhesive for a flexible printed wiring board (hereinafter also referred to as “FPC”). In addition to adhesiveness to a wiring board and solder heat resistance, which are generally required as an adhesive for FPC, the present invention relates to an adhesive composition in which a decrease in adhesive strength is small even when exposed to a high temperature environment for a long time. The present invention also relates to an adhesive film that does not cause defects in product appearance such as warpage of the substrate after bonding.

In recent years, with the diversification of electronic devices such as miniaturization and high density, demand for flexible circuit boards or flexible printed wiring boards is increasing. Under such circumstances, high integration and multilayering are also progressing in the manufacture of flexible printed circuit boards.
The flexible copper-clad laminate is a structure in which copper foil is bonded to one or both sides of a flexible insulating base film via an adhesive layer. Often, a highly reliable polyimide film is used. Furthermore, this flexible copper-clad wiring board becomes an FPC in which a conductive circuit is formed on a copper foil through processes such as resist layer formation, exposure, development, etching, and resist layer peeling.
These FPCs have adhesives for bonding the insulating base film of the flexible copper clad laminate and the copper foil, coverlay adhesives, interlayer adhesives, etc. for the purpose of protecting and insulating the conductive circuit. Adhesives, semiconductor sealants and the like are widely used.
Conventionally, various adhesives containing an epoxy resin and a thermoplastic resin having high reactivity have been proposed as those used for bonding an insulating base film and a metal, insulating base films, and metals. For example, Patent Document 1 proposes a carboxyl group-containing acrylonitrile butadiene rubber / epoxy resin adhesive. Patent Document 2 proposes a glycidyl group-containing elastomer / epoxy resin adhesive. Patent Document 3 proposes a carboxyl group-containing ethylene acrylic elastomer / epoxy resin adhesive. Patent Document 4 proposes a polyesteramide resin / epoxy resin adhesive having an acid value. Patent Document 5 proposes a polyester polyurethane resin / epoxy resin adhesive having an acid value. Patent Document 6 proposes a nylon / epoxy resin adhesive. The adhesives shown in these prior art documents utilize the reactivity of the carboxyl groups of rubber and elastomer components and the epoxy resin, realize a rapid curing reaction, and are excellent in adhesiveness. Generally used widely.

JP-A-6-49427 JP 2001-354936 A JP-A-7-235767 Japanese Patent Laid-Open No. 2006-152015 Japanese Patent Laid-Open No. 2005-244139 JP 2000-188451 A

  However, the adhesives disclosed in Patent Documents 1 to 6 have a problem in that the adhesiveness between the constituent rubber or elastomer and the polyimide resin is insufficient, and peeling easily occurs. Further, when a laminated board made of polyimide / adhesive / copper foil is exposed to a high temperature environment of 150 ° C. or 200 ° C., there is a problem that the adhesiveness greatly decreases after several tens of hours. In addition, as a coverlay film with an adhesive that is coated and dried with an adhesive on an insulating film such as polyimide, the problem that the curing reaction of the adhesive proceeds due to the thermal history during storage or transportation during storage or transportation There is. When the coverlay film that has undergone the curing reaction is heated and bonded to the copper foil, the resin flow-out property is poor, so that the circuit groove cannot be embedded sufficiently and the circuit insulation cannot be maintained. Moreover, since adhesiveness with copper foil also worsens, there existed a problem that peeling and a swelling generate | occur | produce in the fall of peeling adhesive strength and the heating process in a solder reflow furnace. This phenomenon is due to the fact that the carboxyl group, epoxy group or amide group in the rubber or elastomer component constituting the adhesive proceeds with the epoxy resin even at a relatively low temperature, and the melt viscosity during heat bonding is too high. The cause is that it became a state.

  The present invention solves the above problems, and an object of the present invention is to provide an adhesive composition in which the adhesiveness does not deteriorate even when the adhesive is left in a high temperature environment for a long time. Moreover, when it uses for FPC, it expresses the outstanding adhesive strength with respect to a polyimide film, and provides the adhesive composition excellent in heat aging resistance and solder heat resistance.

As a result of intensive studies to solve the above problems, the present inventors have found that the heat aging resistance of the adhesive is improved by using a specific polyurethane resin, an epoxy resin, a phenol resin having a triazine ring, and a phenoxy resin. I found it. Moreover, when the adhesive composition of this invention was used for FPC, it discovered that it was excellent in the adhesiveness with respect to a polyimide film, heat aging resistance, and solder heat resistance. Furthermore, when the said adhesive composition contains the melamine resin, it discovered that it was excellent in solder heat resistance even in the state which the bonded laminated body absorbed moisture, and came to complete this invention.
In the present invention, solder heat resistance under hygroscopic conditions is referred to as “hygroscopic solder heat resistance”.

That is, the adhesive composition according to the present invention is as follows.
1. An adhesive composition containing a polyurethane resin (A), an epoxy resin (B), a phenol resin (C) having a triazine ring and a phenoxy resin (D), wherein the polyurethane resin (A) has a melting point of 30 to 150. An adhesive composition characterized by being at ° C.
2. 2. The adhesive composition according to 1 above, wherein the epoxy resin (B) is a mixture of a resin (b1) having two epoxy groups in one molecule and a polyfunctional epoxy resin (b2). .
3. The epoxy equivalent ratio (b1 / b2) of the resin (b1) having two epoxy groups in one molecule and the polyfunctional epoxy resin (b2) is 0.1 to 4.0, The adhesive composition according to 2 above.
4). Content of the said epoxy resin (B) is 20-500 mass parts with respect to 100 mass parts of said polyurethane resins (A), The adhesive composition in any one of said 1-3 characterized by the above-mentioned.
5. Any one of the above 1-4, wherein the phenol resin (C) having a triazine ring has a hydroxyl group equivalent of 0.1-2.0 equivalents relative to 1.0 equivalent of the epoxy resin (B). An adhesive composition according to claim 1.
6). Content of the said phenoxy resin (D) is 30-300 mass parts with respect to 100 mass parts of said polyurethane resins (A), The adhesive composition in any one of said 1-5 characterized by the above-mentioned.
7). Furthermore, melamine resin (E) is contained, The adhesive composition in any one of said 1-6 characterized by the above-mentioned.
8). Content of the said melamine resin (E) is 20-40 mass parts with respect to 100 mass parts of said polyurethane resins (A), The adhesive composition of said 7 characterized by the above-mentioned.
9. A coverlay film, wherein the adhesive composition according to any one of 1 to 8 is applied to one side of a polyimide film.
10. A flexible copper-clad laminate comprising the adhesive composition according to any one of 1 to 8 above, wherein a copper foil is bonded to at least one surface of a polyimide film.

  The adhesive composition which concerns on this invention contains the polyurethane resin which has melting | fusing point in 30-150 degreeC, the epoxy resin, the phenol resin which has a triazine ring, and a phenoxy resin as mentioned above. Therefore, even when the adhesive is left in a high temperature environment for a long time, the adhesive strength can be maintained. Moreover, when it uses for FPC, high adhesive strength with respect to a polyimide film etc. is expressed, and it is excellent in heat aging resistance and solder heat resistance. When the adhesive composition of the present invention further contains a melamine resin, it is excellent in solder heat resistance even in a state where the bonded laminate has absorbed moisture.

  An embodiment of the present invention will be described as follows, but the present invention is not limited to this.

-Adhesive composition The adhesive composition according to the present invention contains a polyurethane resin (A), an epoxy resin (B), a phenol resin (C) having a triazine ring, and a phenoxy resin (D), respectively. The resin is as follows.

  Details of the polyurethane resin (A) used in the present invention will be described. The polyurethane resin used in the present invention plays a role of increasing the adhesive strength between an insulating film such as polyimide and a copper foil. The polyurethane resin used in the present invention is composed of various polyols and polyisocyanates, and is a polyurethane resin having a crystallinity with a melting point of 30 ° C. to 150 ° C.

  Any known compound can be used as the polyol component constituting the crystalline polyurethane resin used in the present invention. For example, polyether diol, polyester diol, polycaprolactone diol, polycarbonate diol, castor oil, acrylic polyol, polybutadiene diol and the like can be mentioned. Polyether diols and polyester diols are preferred.

  Examples of the polyether diol include polyethylene glycol, polypropylene glycol, and polytetramethylene ether glycol. The polyester-based diol is produced by a condensation reaction between a polyol and a polybasic acid. Examples of the polyol component include ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, neo Pentyl glycol, 3-methylpentanediol, and the like can be used. As the polybasic acid component, adipic acid, azelaic acid, sebacic acid, isophthalic acid, terephthalic acid and the like can be used.

  As the polyisocyanate component constituting the polyurethane resin used in the present invention, any known compound can be used. For example, aromatic polyisocyanates such as 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4′-diphenylmethane diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, isophorone diisocyanate, tetramethylxylylene diisocyanate, etc. And aliphatic diisocyanates. Aromatic polyisocyanates are preferred.

The melting point of the polyurethane resin (A) used in the present invention is 30 to 150 ° C. and has crystallinity. The melting point is preferably 35 to 120 ° C, more preferably 40 to 90 ° C. When melting | fusing point is less than 30 degreeC, the melt viscosity of the adhesive composition at the time of heat bonding of the copper foil bonding process of a coverlay becomes low, and the flow-out property of the resin at the time of heat bonding becomes large too much. For this reason, the resin is covered on the connection contact portion, and the energization becomes insufficient. On the other hand, when the melting point exceeds 150 ° C., the melt viscosity of the resin at the time of heat bonding in the copper foil laminating step is too high, so that the circuit embedding property is deteriorated and the insulation reliability is lowered.
When an amorphous urethane resin having no melting point is used, an adhesive composition having excellent heat aging resistance cannot be obtained.

  The acid value of the polyurethane resin (A) used in the present invention is preferably 5 mgKOH / g or less, and the polyurethane resin used in the present invention is substantially less reactive with an epoxy resin due to a carboxyl group. It is a feature. That is, even after the adhesive composition of the present invention is heat-cured and the reaction is sufficiently completed and the entire adhesive forms a crosslinked structure, a crosslinked structure due to carboxyl groups in the polyurethane resin used in the present invention is formed. Means not. As an index of reactivity with the epoxy resin, the acid value is preferably 5 mgKOH / g or less, more preferably 3 mgKOH / g or less, and further preferably 1 mgKOH / g or less. When a polyurethane resin with an acid value exceeding 5 mgKOH / g is used, the reaction between the polyurethane resin and the epoxy is likely to occur at a relatively low temperature. Therefore, the crosslinking reaction occurs due to the thermal history during storage and transportation of the coverlay coated with adhesive. May progress. Therefore, since the melt viscosity of the resin becomes too high at the time of heat bonding in the copper foil laminating process of the cover lay, the embedding in the circuit groove becomes insufficient and the insulation of the circuit cannot be maintained. Moreover, since adhesiveness with copper foil also worsens, adhesive strength falls.

  The weight average molecular weight (Mw) of the polyurethane resin (A) used in the present invention is preferably 50,000 to 500,000, and more preferably 100,000 to 300,000. When the weight average molecular weight (Mw) is in this range, an adhesive composition having excellent adhesion and heat aging resistance can be obtained.

Next, the epoxy resin (B) used in the present invention will be described.
The epoxy resin (B) used in the present invention plays a role for developing the heat resistance and high adhesiveness of the cured adhesive.
Examples of epoxy resins include bisphenol A type epoxy resins, bisphenol F type epoxy resins, or those hydrogenated to them; orthophthalic acid diglycidyl ester, isophthalic acid diglycidyl ester, terephthalic acid diglycidyl ester, p-hydroxybenzoic acid Glycidyl ester epoxy resins such as glycidyl ester, tetrahydrophthalic acid diglycidyl ester, succinic acid diglycidyl ester, adipic acid diglycidyl ester, sebacic acid diglycidyl ester, trimellitic acid triglycidyl ester; ethylene glycol diglycidyl ether, propylene glycol Diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpro Triglycidyl ether, pentaerythritol tetraglycidyl ether, tetraphenyl glycidyl ether ethane, triphenyl glycidyl ether ethane, polyglycidyl ether of sorbitol, polyglycidyl ether of polyglycerol, etc .; triglycidyl isocyanurate, tetraglycidyl diamino Examples thereof include, but are not limited to, glycidylamine epoxy resins such as diphenylmethane; linear aliphatic epoxy resins such as epoxidized polybutadiene and epoxidized soybean oil. Moreover, novolak-type epoxy resins such as phenol novolac epoxy resin, o-cresol novolac epoxy resin, and bisphenol A novolac epoxy resin can also be used.

  Further, as examples of epoxy resins, brominated bisphenol A type epoxy resins imparted with flame retardancy, phosphorus containing epoxy resins, dicyclopentadiene skeleton containing epoxy resins, naphthalene skeleton containing epoxy resins, anthracene type epoxy resins, tertiary butyl catechol type An epoxy resin, a triphenylmethane type epoxy resin, a tetraphenylethane type epoxy resin, a biphenyl type epoxy resin, a bisphenol S type epoxy resin, or the like can be used.

In the adhesive composition according to the present invention, in order to form a crosslinked structure by reaction with a phenol resin having a triazine ring and to exhibit high heat resistance, the epoxy resin has two or more epoxy groups in one molecule. It is preferable to use one having When an epoxy resin having one epoxy group is used, sufficient solder heat resistance may not be obtained because the degree of crosslinking with a phenol resin having a triazine ring is low.
Furthermore, the epoxy resin is preferably a mixture of a resin (b1) having two epoxy groups in one molecule and a polyfunctional epoxy resin (b2). Only with the epoxy resin (b1), the degree of crosslinking with a phenol resin having a triazine ring is still low, so that sufficient solder heat resistance and moisture absorption solder heat resistance may not be obtained. On the other hand, with only the polyfunctional epoxy resin (b2), the crosslinking density of the cured product tends to be too high. As a result, flexibility may not be exhibited, or adhesion to the adherend may be insufficient. If it is the said mixture, the adhesive composition which is excellent by initial stage adhesiveness and heat aging resistance can be obtained. The combination of the epoxy resin (b1) and the epoxy resin (b2) includes bisphenol A type epoxy resin and phenol novolac epoxy resin, bisphenol A type epoxy resin and naphthalene skeleton-containing epoxy resin, bisphenol A type epoxy resin and glycidylamine epoxy. Examples thereof include, but are not limited to, resins, bisphenol F-type epoxy resins and naphthalene skeleton-containing epoxy resins, and bisphenol F-type epoxy resins and glycidylamine-based epoxy resins.
In the present invention, the polyfunctional epoxy resin means one having three or more epoxy groups in one molecule.

  The mass ratio (b1 / b2) of the resin (b1) having two epoxy groups in one molecule and the polyfunctional epoxy resin (b2) is preferably 20/80 to 95/5, It is more preferably 40/60 to 90/10, and further preferably 50/50 to 90/10. If the ratio of the resin (b1) is less than 20, the crosslink density of the cured product becomes too high, and the initial adhesiveness may be lowered. On the other hand, when the ratio of the resin (b1) exceeds 95, solder heat resistance and moisture absorption solder heat resistance may be insufficient.

  The epoxy equivalent ratio (b1 / b2) of the resin (b1) having two epoxy groups in one molecule and the polyfunctional epoxy resin (b2) is preferably 0.1 to 4.0, 0 More preferably, it is 0.1 to 3.0, and further preferably 0.2 to 2.0. If the equivalent ratio is less than 0.1, the crosslink density of the cured product becomes too high, and the initial adhesiveness may be lowered. On the other hand, if the equivalent ratio exceeds 4.0, solder heat resistance and moisture-absorbing solder heat resistance may be insufficient.

  The content ratio of the polyurethane resin (A) and the epoxy resin (B) in the adhesive composition of the present invention is within a range of 20 to 500 parts by mass of the epoxy resin (B) with respect to 100 parts by mass of the polyurethane resin (A). It is preferable to contain. More preferably, an epoxy resin is 30-300 mass parts, More preferably, it is 50-200 mass parts. When the content ratio of the epoxy resin is less than 20 parts by mass, the elastic modulus of the adhesive after the curing process is low, and thus sufficient heat resistance cannot be obtained. On the other hand, when the content ratio of the epoxy resin exceeds 500 parts by mass, the content ratio of the polyurethane resin is decreased, so that the adhesive strength with an insulating film or a copper foil is lowered.

Next, the phenol resin (C) having a triazine ring used in the present invention will be described.
The phenol resin (C) having a triazine ring used in the present invention can be produced, for example, by the method described in JP-A No. 11-21419. Specifically, it can be obtained by subjecting a phenol, a compound having an amino group-containing triazine ring, and an aldehyde to a condensation reaction. As a phenol resin (C) which has a triazine ring, what is represented by General formula (1) is mentioned, for example.

  Since the phenol resin (C) having a triazine ring forms a crosslinked structure by reaction with an epoxy resin, it has an effect of improving the heat resistance of the adhesive. In addition, it plays a role of improving adhesion with copper. Further, when a phenol resin (C) having a triazine ring is used, a resin having a particularly high heat aging resistance can be obtained.

  The equivalent ratio of the epoxy resin (B) used in the present invention and the phenol resin (C) having a triazine ring is 0.1 to 2 with respect to the epoxy equivalent of 1.0. It is preferable to contain within the range of 0.0. More preferably, it is 0.2-1.5, More preferably, it is 0.3-1.0. If the equivalent ratio of the phenol resin having a triazine ring is less than 0.1, the elastic modulus of the adhesive after the curing treatment is low, and thus sufficient heat resistance characteristics may not be obtained. On the other hand, if the equivalent ratio of the phenol resin having a triazine ring exceeds 2.0, the elastic modulus of the adhesive after the curing treatment is increased, so that the adhesive strength with an insulating film or copper foil may be reduced. .

Next, the phenoxy resin (D) used in the present invention will be described.
The phenoxy resin (D) used in the present invention has an effect of improving the initial adhesiveness and heat aging resistance of the adhesive.
Examples of the phenoxy resin include bisphenol A type phenoxy resin, bisphenol F type phenoxy resin, bisphenol S type phenoxy resin, and phosphorus-based phenoxy resin. The terminal structure of the phenoxy resin is not limited, and those having a hydroxyl group or a glycidyl group can be used. Moreover, although arbitrary things can be used also about molecular weight, the thing of Mw 30000-100000 is preferable. If Mw is within this range, the adhesion to the adherend is good and the heat aging resistance is also excellent.

  The content of the phenoxy resin (D) is preferably 30 to 300 parts by mass and more preferably 100 to 250 parts by mass with respect to 100 parts by mass of the polyurethane resin (A). When the content of the phenoxy resin is within this range, an adhesive composition excellent in adhesiveness and heat aging resistance can be obtained.

The adhesive composition of the present invention can further contain a melamine resin (E). The melamine resin serves to crosslink non-crosslinked components in the cured product by reacting with the polyurethane resin (A), the phenoxy resin (D), and the like. By this crosslinking, the elastic modulus of the cured product at a high temperature is improved, and excellent moisture-absorbing solder heat resistance can be obtained.
The content of the melamine resin (E) is preferably 20 to 40 parts by mass and more preferably 25 to 35 parts by mass with respect to 100 parts by mass of the polyurethane resin (A). If content of a melamine resin is in the said range, the adhesive composition excellent in moisture absorption solder heat resistance can be obtained.

  The adhesive composition of the present invention has the purpose of the present invention for various purposes such as improvement of adhesiveness and improvement of solution properties in addition to polyurethane resin, epoxy resin, phenol resin having triazine ring, phenoxy resin and melamine resin. It is possible to add additives arbitrarily within a range not to be impaired. For example, melamine resin curing accelerators, resin components such as thermoplastic resins, thermoplastic elastomers and rubbers, polyurethane resin curing agents, coupling agents, antioxidants, UV absorbers, leveling agents, antifoaming agents, thickening agents Agents, flame retardants, fillers, dyes and the like. It is also possible to add and disperse filler components such as titanium oxide, zinc oxide, talc, calcium carbonate, aluminum hydroxide, carbon black and silica. The additive can be added at the time of dissolving the raw material in the solvent or after dissolution.

  Examples of the curing accelerator for the melamine resin include phosphoric acid, p-toluenesulfonic acid and derivatives thereof, trifluoromethanesulfonic acid, monobutyl phosphate, dibutyl phosphate, boron trifluoride, benzoic acid, 1,2-benzenedicarboxylic acid. Acid, 1,3-benzenedicarboxylic acid, 1,4-benzenedicarboxylic acid, 1,2,3-benzenetricarboxylic acid, 1,2,4-benzenetricarboxylic acid (trimellitic acid), 1,3,5-benzene A tricarboxylic acid etc. are mentioned.

  Examples of the resin component include acrylonitrile butadiene rubber, acrylic rubber, acrylic ethylene rubber, isoprene rubber, ethylene propylene rubber, ethylene propylene diene rubber, ethylene propylene α olefin rubber, ethylene vinyl acetate elastomer, polyester urethane elastomer, polyether urethane elastomer. , Polycarbonate urethane elastomer, styrene butadiene styrene elastomer, styrene isoprene styrene elastomer, styrene ethylene butylene styrene elastomer, styrene ethylene propylene styrene elastomer, polyester elastomer, polyethylene, polypropylene, polyacrylonitrile styrene, polymethyl methacrylate, polystyrene, polyvinyl alcohol, poly vinegar Vinyl, polyvinyl butyral, polycarbonate, polyacetal, fluorine resin, polyvinyl chloride, and urea resins. Moreover, what modified | denatured these resin and gave the carboxyl group, the epoxy group, the isocyanate group, the hydroxyl group, the thiol group, etc. is mentioned.

  Examples of the curing agent for the polyurethane resin include polyisocyanate compounds, polyvalent carboxylic acid compounds and acid anhydrides thereof.

  Examples of coupling agents include vinyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, p-styryltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-acryloxypropyltrimethoxysilane, N- 2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-ureidopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane, bis (triethoxysilylpropyl) tetrasulfide, 3-isocyanatopropyltriethoxysilane, etc. Silane coupling agents, titanate coupling agents, aluminate coupling agents, zirconium coupling agents, and the like.

  Examples of antioxidants include 2,6-di-o-butyl-4-methylphenol, n-octadecyl-3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenyl) propionate, Tetrakis [methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] methane, pentaerythrityl-tetrakis-3- (3,5-di-t-butyl-4-hydroxyphenyl) Phenolic antioxidants such as propionate, sulfur antioxidants such as dilauryl-3,3′-thiodipropionate, dimyristyl-3,3′-dithiopropionate, trisnonylphenyl phosphite, tris (2, Phosphorus antioxidants such as 4-di-t-butylphenyl) phosphite and triisodecyl phosphite.

  Examples of UV absorbers include 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2- [2′-hydroxy-3 ′, 5′-bis (α, α-dimethylbenzyl) phenyl]. -Benzotriazole ultraviolet absorbers such as benzotriazole, benzophenone ultraviolet absorbers such as 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-n-octylbenzophenone, phenyl salicylate, etc. Salicylate-based UV absorbers, cyanoacrylate-based UV absorbers such as ethyl-2-cyano-3,3-diphenyl acrylate, and azalic anilide-based UV absorbers such as 2-ethoxy-2'-ethyl oxalic acid bisanilide Agent, bis- [2,2,6,6-tetramethyl-4 Hindered ultraviolet absorbers such as -piperidinyl] sebacate and bis- [N-methyl-2,2,6,6-tetramethyl-4-piperidinyl] sebacate].

  Examples of flame retardants include brominated flame retardants such as tetrabromobisphenol A, hexabromobenzene, decabromodiphenyl ether, hexabromocyclododecane, bis (pentabromophenyl) ethane, bis (tetrabromophthalimide) ethane, and triphenyl phosphate. , Aromatic phosphate ester flame retardants such as 2-ethylhexyl diphenyl phosphate, cresyl diphenyl phosphate, 1,3-phenylene bis (diphenyl phosphate), 1,3-phenylene bis (dixylenyl) phosphate, bisphenol A bis (diphenyl phosphate) ) Aromatic condensed phosphate esters such as tris (dichloropropyl) phosphate, halogen-containing phosphate ester flame retardants, red phosphorus flame retardants such as red phosphorus, aluminum hydroxide, water Magnesium, inorganic flame retardants such as antimony trioxide, silicon-based flame retardant, such as boron-based flame retardants and the like.

In the present invention, an adhesive composition containing, as essential components, a polyurethane resin, an epoxy resin, a phenol resin having a triazine ring, and a phenoxy resin, together with the melamine resin and optional additives, is usually dissolved in a solvent to form a solution. Used as an adhesive.
Specific examples of the solvent include ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl amyl ketone and cyclohexanone, aromatic solvents such as toluene, xylene, ethylbenzene and mesitylene, methyl acetate, ethyl acetate and ethylene glycol. Examples include ester solvents such as monomethyl ether acetate and 3-methoxybutyl acetate, and chlorine solvents such as chloroform, carbon tetrachloride, dichloromethane, and trichloroethylene.
Moreover, as a resin density | concentration when using as a solution type adhesive agent, 20-60 mass% is preferable, More preferably, it is 25-45 mass%. If the resin concentration is within this range, it is a uniform solution when prepared, and the solution viscosity is also suitable, so that a uniform coating film can be formed when applied to a flexible film.

The FPC in which the adhesive composition of the present invention is used is formed by laminating the following cover lay film and a flexible copper-clad laminate.
Cover Lay Film Examples of the cover lay film include a polyimide film, a polyester film, a polyether ether ketone film, a polyphenylene sulfide film, and an aramid film. A film preferable for the present invention has a film thickness of 12 to 75 μm, and one having a surface treatment such as a corona discharge treatment, a low temperature plasma treatment or a sand blast treatment on one or both sides of the film can be used.

○ Flexible printed wiring board The flexible printed wiring board is a flexible film similar to the above-mentioned coverlay film and a copper foil, bonded together by a method such as roll pressing or hot pressing using an adhesive, and then desired. The copper foil layer is etched on the circuit pattern.

Examples of the method for bonding the flexible film and the copper foil using the adhesive composition include the following methods.
1) An adhesive solution is applied to a flexible film, dried to form an adhesive layer, and a copper foil is laminated thereon and heated to cure the adhesive layer between both substrates.
2) The adhesive solution is applied to a copper foil, dried to form an adhesive layer, and a flexible film is laminated thereon and heated to cure the adhesive layer between both substrates.
3) An adhesive solution is applied to a release film and dried to form an adhesive layer. Next, the adhesive layer and the flexible film are bonded together, the release film is peeled off, the exposed adhesive layer and the copper foil are bonded together, and then the adhesive layer between the two substrates is heated. Is cured.
4) The adhesive solution is applied to a release film and dried to form an adhesive layer. Next, the adhesive layer and the copper foil are bonded together, the release film is peeled off, the exposed adhesive layer and the flexible film are bonded together, and then the adhesive layer is heated between the two substrates by heating. Is cured.

  Examples of the release film include PET film, polyethylene film, polypropylene film, silicone release treated paper, polyolefin resin-coated paper, TPX film, and fluorine resin film that have been subjected to a release treatment.

  The adhesive solution is applied by a method such as brush coating, dip coating, spray coating, comma coating, knife coating, die coating, lip coating, roll coater coating or curtain coating. The dry film thickness after coating is preferably 1 to 100 μm, more preferably 10 to 50 μm. The adhesive solution applied to the substrate is preferably dried by heating at a temperature of 40 to 250 ° C., more preferably 70 to 170 ° C., through a furnace such as hot air drying, far infrared heating, high frequency induction heating or the like. As a method for curing the adhesive layer in which the two substrates are overlapped, a method of heating through a furnace such as hot air drying, far-infrared heating, high-frequency induction heating or the like at a temperature of 80 to 250 ° C. is used. Among them, the heating method under pressure by a heating press is preferable for obtaining high adhesiveness.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples as long as the gist of the present invention is not exceeded. In the following, “part” and “%” are based on mass unless otherwise specified.

1. Evaluation method The component contained in an adhesive composition and the evaluation method of the laminated body which adhere | attached are as follows.
1-1. Melting point Using a differential scanning calorimeter, the temperature was measured from -100 to 200 ° C at a rate of temperature increase of 10 ° C / min, and the temperature at which an endothermic peak accompanying crystal melting was observed was taken as the melting point. For the polyurethane resin having no melting point, no endothermic peak was observed.

1-2. Acid value 1 g of polyurethane resin was dissolved in 40 ml of methyl ethyl ketone, and an automatic titration apparatus “AT-510” manufactured by Kyoto Denshi Kogyo Co., Ltd., connected with “APB-510-20B” manufactured by the same company as a burette was used. Potentiometric titration was performed using a 0.01 mol / L benzyl alcoholic KOH solution as a titration reagent, and the number of mg of KOH per 1 g of resin was calculated.

1-3. Weight average molecular weight (Mw)
Using a gel permeation chromatograph (model name “HLC-8120”, manufactured by Tosoh Corporation), Mw was measured under the following conditions, and converted to standard polystyrene.
<Measurement conditions>
Column: 4 TSKgel SuperMultipore HZ-M (manufactured by Tosoh Corporation)
Column temperature: 40 ° C
Eluent: Tetrahydrofuran Detector: RI

1-4. Peeling adhesive strength The adhesive solution was applied to a polyimide film having a thickness of 25 μm (trade name “Kapton 100EN” manufactured by Toray Industries Inc.) so that the film thickness after drying was 25 μm, and further dried at 80 ° C. for 2 minutes. Dry at 150 ° C. for 2 minutes. Next, a rolled copper foil having a thickness of 35 μm was bonded and laminated under the conditions of 80 ° C., 0.3 MPa, and 0.5 m / min. Further, this polyimide film / adhesive layer / copper foil laminate was heat-pressed for 1 minute at 170 ° C. and 1.5 MPa, and then heat-cured at 170 ° C. for 2 hours.
The laminate was cut to a width of 10 mm, and the peel adhesion strength when peeling the polyimide film from the copper foil was measured with a tensile tester under a temperature condition of 23 ° C. (unit: N / mm). At this time, the tensile speed was 50 mm / min. The measured value at this time was defined as the initial peel adhesion strength.

1-5. Heat aging resistance Heat aging test (1): The laminate was heat-treated at 200 ° C. for 50 hours and cut into a width of 10 mm. Next, the peel adhesion strength when peeling the polyimide film from the copper foil was measured with a tensile tester under a temperature condition of 23 ° C. (unit: N / mm). At this time, the tensile speed was 50 mm / min. The measured value at this time was defined as the peel adhesion strength after heat aging at 200 ° C.
Heat aging test (2): The laminate was heat-treated at 150 ° C. for 1000 hours and cut into a width of 10 mm. Next, the peel adhesion strength when peeling the polyimide film from the copper foil was measured with a tensile tester under a temperature condition of 23 ° C. (unit: N / mm). At this time, the tensile speed was 50 mm / min. The measured value at this time was defined as the peel adhesion strength after heat aging at 150 ° C.

1-6. Solder heat resistance The laminate was cut into 20 mm squares and left in a constant temperature room at 23 ° C. and 50% RH for 1 day, and then placed in a solder bath melted at 260 ° C. for 60 seconds with the polyimide film face up. It floated and the state change of the test piece was observed.
○: No change from the state before the test ×: Swelling and peeling occurred on the entire specimen surface

1-7. Moisture-absorbing solder heat resistance The laminate cut into 20 mm width is left in a constant temperature and humidity machine at 40 ° C. and 80% RH for 3 days, and then a solder bath melted at 260 ° C. with the polyimide film face up The specimen was floated for 60 seconds, and the state change of the test piece was observed.
○: No change from the state before the test ×: Swelling and peeling occurred on the entire specimen surface

2. Production of adhesive composition Example 1
100 parts by mass of a polyurethane resin (trade name “Pearl Bond 508” manufactured by Melkinsa Co., Ltd.), 120 parts by mass of a bisphenol F type epoxy resin (trade name “jER4004P” manufactured by Japan Epoxy Resin Co., Ltd.), and a naphthalene skeleton epoxy resin (trade name “manufactured by DIC” HP-4700 ”) 20 parts by mass, phenol resin having a triazine ring (trade name“ Phenolite LA-1356 ”manufactured by DIC) 30 parts by mass [hydroxyl equivalent / epoxy equivalent = 0.8], phenoxy resin (Nippon Steel) 160 parts by mass (trade name “YP-50EK35” manufactured by Chemical Co., Ltd.), 30 parts by mass of melamine resin (trade name “MX750” manufactured by Sanwa Chemical Co., Ltd.), and 1 part by mass of trimellitic acid, solvent; methyl ethyl ketone 700 Dissolved in parts by mass. Next, an adhesive composition was prepared by the method described below, and various tests were performed by the method described above. The results are shown in Table 1.

○ Examples 2-9, Comparative Examples 1-3
About the composition of Table 1 and 2, the adhesive composition was obtained by the method similar to Example 1. FIG. Next, an adhesive laminate was produced in the same manner as in Example 1, and various tests were conducted in the same manner as in Example 1. The results are shown in Tables 1 and 2.

Abbreviations in Tables 1 and 2 indicate the following.
-Polyurethane resin a-1: Product name “Pearl Bond 508” (Melting point 75 ° C., acid value 0.3 mg KOH / g, Mw 230000) manufactured by Melkinsa
・ Polyurethane resin a-2: trade name “Desmocol 400” manufactured by Sumika Bayer Co., Ltd. (melting point: 50 ° C., acid value: 0 mgKOH / g, Mw230000)
・ Polyurethane resin a-3: trade name “Desmocol 530” (smelting point 75 ° C., acid value 0 mgKOH / g, Mw 190000) manufactured by Sumika Bayer Co., Ltd.
-Polyurethane resin x: DIC Corporation trade name “Pandex T-5102M” (amorphous resin having no melting point, acid value 0 mg KOH / g, Mw 110000)
-Epoxy resin b1-1: product name "jER4004P" manufactured by Japan Epoxy Resin Co., Ltd. (bisphenol F type epoxy resin, epoxy equivalent 880 g / equivalent)
-Epoxy resin b1-2: product name "jER828" manufactured by Japan Epoxy Resin Co., Ltd. (bisphenol A type epoxy resin, epoxy equivalent 189 g / equivalent)
-Epoxy resin b2: Product name "HP-4700" manufactured by DIC (Naphthalene skeleton epoxy resin, epoxy equivalent 163 g / equivalent)
Phenol resin c-1: phenol resin having a triazine ring, product name “Phenolite LA-1356” manufactured by DIC (hydroxyl equivalent 146 g / equivalent, nitrogen content 19%)
-Phenol resin c-2: phenol resin having a triazine ring, manufactured by DIC, trade name “Phenolite LA-1398” (hydroxyl equivalent: 135 g / equivalent, nitrogen content: 22%)
-Phenolic resin y-1: phenolic resin having no triazine ring, product name "Phenolite KA-1165" (hydroxyl equivalent 119 g / equivalent) manufactured by DIC
-Phenolic resin y-2: phenolic resin having no triazine ring, product name "TD-2090" manufactured by DIC (hydroxyl equivalent 105 g / equivalent)
-Phenoxy resin: Nippon Steel Chemical Co., Ltd. trade name “YP-50EK35” (Mw 70000)
・ Melamine resin: product name “MX750” manufactured by Sanwa Chemical Co.
Curing accelerator: Trimellitic acid, manufactured by Matsugaki Pharmaceutical Co., Ltd., trade name “F-TMA”

3. Evaluation of Adhesive Composition From the results shown in Tables 1 and 2, the adhesive composition of the present invention has good initial adhesiveness and excellent heat aging resistance and solder heat resistance.

  The adhesive composition of the present invention can be used for bonding resin films such as polyimide films and PET films, and metal foils such as copper and aluminum. In particular, it is useful for bonding an FPC or a flexible flat cable.

Claims (10)

  An adhesive composition containing a polyurethane resin (A), an epoxy resin (B), a phenol resin (C) having a triazine ring and a phenoxy resin (D), wherein the polyurethane resin (A) has a melting point of 30 to 150. An adhesive composition characterized by being at ° C.   The adhesive composition according to claim 1, wherein the epoxy resin (B) is a mixture of a resin (b1) having two epoxy groups in one molecule and a polyfunctional epoxy resin (b2). object.   The epoxy equivalent ratio (b1 / b2) of the resin (b1) having two epoxy groups in one molecule and the polyfunctional epoxy resin (b2) is 0.1 to 4.0, The adhesive composition according to claim 2.   Content of the said epoxy resin (B) is 20-500 mass parts with respect to 100 mass parts of said polyurethane resins (A), The adhesive agent of any one of Claims 1-3 characterized by the above-mentioned. Composition.   The hydroxyl group equivalent of the phenol resin (C) having the triazine ring is 0.1 to 2.0 equivalents relative to 1.0 equivalent of the epoxy resin (B). The adhesive composition according to any one of the above.   Content of the said phenoxy resin (D) is 30-300 mass parts with respect to 100 mass parts of said polyurethane resins (A), The adhesive agent of any one of Claims 1-5 characterized by the above-mentioned. Composition.   Furthermore, a melamine resin (E) is included, The adhesive composition of any one of Claims 1-6 characterized by the above-mentioned.   Content of the said melamine resin (E) is 20-40 mass parts with respect to 100 mass parts of said polyurethane resins (A), The adhesive composition of Claim 7 characterized by the above-mentioned.   A coverlay film, wherein the adhesive composition according to any one of claims 1 to 8 is applied to one side of a polyimide film.   A flexible copper-clad laminate comprising the adhesive composition according to any one of claims 1 to 8, wherein a copper foil is bonded to at least one surface of a polyimide film.