JP2000144080A - Electro-conductive pressure sensitive adhesive composition and pressure sensitive adhesive product using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an electro-conductive pressure sensitive adhesive compsn. excellent in tackiness and durability, and a pressure sensitive adhesive product using the same. SOLUTION: This electro-conductive pressure sensitive adhesive compsn. comprises 100 pts.wt. acrylic copolymer, 0.01-1 pts.wt. triazole compd., 1-40 pts.wt. metal particles, and 5-50 pts.wt. tackifier resin having a softening temp. not lower than 130 deg.C. It is pref. that the tackifier resin is a polymerized rosin ester tackifier resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure-sensitive adhesive composition in the form of an acrylic emulsion having excellent adhesive strength, excellent conductivity and durability, and a pressure-sensitive adhesive product using the same.

[0002]

2. Description of the Related Art With the spread of electronic devices in recent years, the demand for conductive adhesives for applications such as electromagnetic wave shielding has been increasing. As such an adhesive, Japanese Patent Application Laid-Open No. 1-2221481
Japanese Patent Application Laid-Open Publication No. H11-139,086 discloses a pressure-sensitive adhesive composition having excellent conductivity and durability. However, there is a drawback that the technique described in the above publication alone has low adhesive strength and is not suitable for applications requiring higher adhesive strength.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a conductive pressure-sensitive adhesive composition which solves the above-mentioned conventional disadvantages and has excellent adhesive strength and durability, and a pressure-sensitive adhesive product using the same. I do.

[0004]

The conductive pressure-sensitive adhesive composition according to claim 1 comprises 100 parts by weight of an acrylic copolymer, 0.01 to 1 part by weight of a triazole compound, and 1 to 4 metal particles.
0 parts by weight, tackifying resin 5 having a softening point of 130 ° C. or more
-50 parts by weight.

The invention according to claim 2 is the conductive pressure-sensitive adhesive composition according to claim 1, wherein the tackifying resin is a polymerized rosin ester-based tackifying resin.

According to a third aspect of the present invention, there is provided the conductive pressure-sensitive adhesive composition according to the first aspect, wherein the tackifying resin comprises 3 to 30 parts by weight of a polymerized rosin ester-based tackifying resin and a disproportionated rosin ester-based resin. And 2 to 20 parts by weight of a tackifier resin.

Further, the pressure-sensitive adhesive product of the present invention is characterized in that the conductive pressure-sensitive adhesive composition according to any one of claims 1 to 3 is laminated on the surface of a metal sheet.

[0008] As the acrylic copolymer used in the present invention, those used in ordinary acrylic pressure-sensitive adhesives can be used. Among them, an acrylic copolymer emulsion is particularly preferably used because it can be easily blended. The method for producing the acrylic emulsion is not particularly limited, but a method of emulsion-polymerizing a (meth) acrylate monomer is preferably used.

In the emulsion polymerization, an anionic emulsifier such as sodium lauryl sulfate and sodium dodecylbenzenesulfonate, and a nonionic emulsifier such as polyethylene glycol nonylphenyl ether are used. For the polymerization, a batch charge polymerization method, a monomer sequential addition polymerization method, an emulsion monomer sequential addition polymerization method, or the like is used.

The (meth) acrylate-based monomers used include n-butyl (meth) acrylate,
2-ethylhexyl (meth) acrylate, ethyl (meth) acrylate, and the like. If necessary, a monomer such as methyl methacrylate, (meth) acrylic acid, acrylamide, styrene, or vinyl acetate may be used in combination. You may.

The triazole compounds include benzotriazole, tritriazole and its potassium salt,
Preferred examples include benzotriazole-based compounds such as-(N-salicyloyl) amino-1,2,4 triazole and 2- (2'-hydroxy-5-methylphenyl) benzotriazole, but are not limited thereto. is not.

The method of adding the triazole compound is not particularly limited, but for efficient dispersion and blending, a method in which the triazole compound is dispersed and dissolved in a water-soluble solvent such as acetone, methyl ethyl ketone or methanol in advance and then blended with other components is used. It is suitable. If the amount of the triazole-based compound is less than 0.01 part by weight, the rust-preventing action on the metal powder is insufficient, so that the durability of the conductivity is poor. A large rust prevention effect, that is, durable conductivity cannot be obtained, and the cost increases. Therefore, the amount of the triazole compound added is limited to the range of 0.1 to 1 part by weight.

The type of the metal particles is not limited, and particles such as copper, silver, nickel, and stainless steel, and powders such as glass and plastic whose surfaces are metal-plated are used.
The particle size of the metal particles is preferably 100 μm or less in order to make it difficult for sedimentation and separation when forming an emulsion pressure-sensitive adhesive composition, and from the viewpoint of the finish of the coated surface when applied.

When the amount of the metal particles is less than 1 part by weight, the conductivity is insufficient, and when the amount exceeds 40 parts by weight, the adhesive strength is remarkably reduced, so that the amount added is limited to the range of 1 to 40 parts by weight. Is done.

If the softening point of the tackifying resin is lower than 130 ° C., the adhesive strength becomes insufficient. Therefore, the softening point needs to be 130 ° C. or higher. The type is not limited as long as the softening point is 130 ° C. or higher, and examples thereof include a rosin-based resin, a terpene-phenol-based resin, and a petroleum resin. A rosin-based resin is preferred because of its excellent balance of adhesive performance.

Examples of such an ester include an esterified product of a resin acid such as abietic acid or a derivative thereof such as a dimer, a disproportionate or a hydrogenated product, and glycerin or pentaerythritol. Among them, emulsions of these resins are preferably used because they can be easily blended as components of the emulsion adhesive.

If the amount of the tackifier resin is less than 5 parts by weight, the adhesive strength is insufficient. If the amount is more than 50 parts by weight, the adhesive becomes too hard and the adhesive strength is reduced.
It is limited to ５０50 parts by weight.

The polymerized rosin ester-based tackifying resin blended in the conductive pressure-sensitive adhesive composition according to claims 2 and 3 is an ester of a dimer of a fatty acid such as abietic acid and glycerin, pentaerythritol or the like. Emulsions are preferred because they are easily formulated as adhesives.

The addition amount of the polymerized rosin ester tackifying resin is 5 to 50 parts by weight, preferably 10 to 40 parts by weight in the invention of claim 2. If the amount is less than 5 parts by weight, the adhesive strength will be insufficient, and if it exceeds 50 parts by weight, the adhesive will be too hard and conversely the adhesiveness will decrease.

According to the third aspect of the present invention, the amount of the polymerized rosin ester is 3 to 30 parts by weight, preferably 5 to 2 parts by weight.
0 parts by weight. If the amount is less than 3 parts by weight, the adhesive strength becomes insufficient,
If the amount exceeds 0 parts by weight, the pressure-sensitive adhesive becomes too hard, and conversely, the pressure-sensitive adhesive strength decreases.

The disproportionated rosin ester-based tackifying resin used in the invention according to claim 3 is an esterified product of a disproportionate of a resin acid such as abietic acid and glycerin, pentaerythritol or the like. Is preferred because it is easily compounded as an adhesive.

The addition amount of the disproportionated rosin ester-based tackifying resin is 2 to 20 parts by weight, preferably 5 to 15 parts by weight. If it is less than 2 parts by weight, the adhesive strength will be insufficient, and if it exceeds 20 parts by weight, the adhesive strength will be reduced.

The method of compounding the above components is not limited, but for efficient and simple compounding, the acrylic resin and the tackifying resin are prepared in advance as an emulsion, and after premixing these with the triazole compound, the conductive powder is prepared. The method of mixing the bodies is preferred. In addition, the viscosity of the emulsion of the pressure-sensitive adhesive composition of the present invention is 1000 mPas, and the thixotropic index (the number obtained by dividing the viscosity at 2 rpm by the viscosity at 20 rpm with a B-type rotational viscometer) is 3 or more. ,
It is suitably used because it has a large effect of preventing sedimentation of metal particles.

The conductive pressure-sensitive adhesive composition of the present invention may optionally contain an antifoaming agent, a thickener, a filler, a film-thickening aid, and the like.

According to a fourth aspect of the present invention, there is provided a processed pressure-sensitive adhesive product wherein the conductive pressure-sensitive adhesive composition according to any one of the first to third aspects is laminated on the surface of a metal sheet. As a metal sheet,
Aluminum, copper, stainless steel, etc. are used, and the thickness thereof is usually preferably about 10 to 70 μm.

[0026]

Embodiments of the present invention will be described below. Production of Acrylic Copolymer Emulsion 30 parts by weight of water and 0.1 part by weight of ammonium persulfate were charged into a four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen blowing line. After the temperature was raised to 4, the emulsified monomer mixture having the following composition was added dropwise over 4 hours. After the addition was completed, the mixture was further reacted for 3 hours to obtain an acrylic copolymer emulsion having a solid content of 50%. Composition of emulsified monomer mixture n-butyl acrylate 49.5 parts by weight 2-ethylhexyl acrylate 50 parts by weight Acrylic acid 0.5 parts by weight Water 70 parts by weight Dodecyl mercaptan 0.05 parts by weight Sodium lauryl sulfate 0.5 parts by weight Nonionic emulsifier (Daiichi Kogyo Seiyaku Co., Ltd., trade name "Neugen EA140") 1.0 part by weight

(Examples 1 to 4, Comparative Examples 1 to 4) Preparation of pressure-sensitive adhesive composition In addition to the metal particles, tackifier resin emulsion, and triazole-based compound shown in Table 1, the above acrylic copolymer emulsion was dispersed. 0.1 part by weight of an agent (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trade name "Neogen P") and 0.1 part by weight of an antifoaming agent (manufactured by San Nopco Co., Ltd., trade name "SN Deformer") A composition was obtained.

[0028]

[Table 1] [Note] Amounts are by weight Metal particles: Nickel powder (INCO, type 255) Tackifying resin A: Disproportionated rosin ester resin emulsion, softening point 125 ° C, solid content 55% (Arakawa Chemical Co., Ltd., product Name "Superester E-730-55") Tackifying resin B: Disproportionated rosin ester resin emulsion, softening point 100 ° C, solid content 50% (Arakawa Chemical Co., trade name "Superester E-720") Application resin C: Polymerized rosin ester resin emulsion, softening point 125 ° C, solid content 50% (trade name “Super Ester E-625” manufactured by Arakawa Chemical Co.) Tackifying resin D: Polymerized rosin ester resin emulsion, softening point 160 ° C , Solid content 50% (trade name “Superester E-650” manufactured by Arakawa Chemical Co., Ltd.) Triazole A: benzotriazole (33% acetate Down solution)

Preparation of pressure-sensitive adhesive sheet The above pressure-sensitive adhesive composition was separately coated on a PET film having a thickness of 25 μm and a copper foil having a thickness of 50 μm using a doctor blade so that the thickness after drying was 25 μm. It was dried at 80 ° C. for 5 minutes to obtain an adhesive sheet.

Performance Evaluation (1) Adhesion: Adhesion at 20 ° C. according to JIS Z 0237 using SUS plate and polyethylene plate as adherends using an adhesive sheet based on the PET film. Was measured. (2) Electric resistance (conductivity): Using a pressure-sensitive adhesive sheet based on copper foil, the electric resistance of the sample accelerated and aged at 60 ° C. and 95% RH for 6 months and the sample before the accelerated aging were measured. It was measured. As shown in FIG. 1, the pressure-sensitive adhesive sheets B and C are arranged and pressed on the epoxy resin-impregnated glass plate 3, and the pressure-sensitive adhesive sheet A is attached so as to straddle these, and the electric resistance is measured by the tester 4. did. FIG. 2 is a cross-sectional view taken along the line II-II of FIG. 1, and 1 is a copper foil and 2 is a conductive adhesive. Table 1 shows the above results.

[0031]

Industrial Applicability The conductive pressure-sensitive adhesive composition of the present invention has excellent adhesive strength, and excellent conductivity and durability. The pressure-sensitive adhesive product using the composition is used for electronic equipment, electromagnetic wave shielding and the like. Can be suitably used.

[Brief description of the drawings]

FIG. 1 is a plan view showing a method for measuring electric resistance.

FIG. 2 is a sectional view taken along line II-II in FIG.

[Explanation of symbols]

 A, B, C: Adhesive sheet 1: Copper foil 2: Conductive adhesive 3: Epoxy weight part impregnated glass plate 4: Tester

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C09J 193: 04) F-term (Reference) 4J004 AA03 AA04 AA06 AA10 AA12 AA18 AA19 AB01 CA06 CA08 CC02 FA05 4J040 BA202 DF041 DF051 GA07 GA22 HA066 HC25 JA09 JB07 JB09 JB10 KA26 LA01 LA06 LA09 MA02 MB03 MB05 NA19

Claims (4)

[Claims] 1. An acrylic copolymer (100 parts by weight), a triazole compound (0.01 to 1 part by weight), and metal particles (1 to 4).
0 parts by weight, tackifying resin 5 having a softening point of 130 ° C. or more
An electrically conductive pressure-sensitive adhesive composition comprising 50 to 50 parts by weight. 2. The conductive pressure-sensitive adhesive composition according to claim 1, wherein the tackifier resin is a polymerized rosin ester-based tackifier resin. 3. The conductive pressure-sensitive adhesive composition according to claim 1, wherein the tackifying resin comprises 3 to 30 parts by weight of a polymerized rosin ester-based tackifying resin and 2 to 20 parts by weight of a disproportionated rosin ester-based tackifying resin. . 4. A pressure-sensitive adhesive product comprising the conductive pressure-sensitive adhesive composition according to claim 1 laminated on a surface of a metal sheet.