JP2014136778A - Conductive adhesive sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a conductive adhesive sheet which has satisfactory adhesiveness and conductivity even in thin type and hardly causes deterioration in adhesive force with time.SOLUTION: There is provided a conductive adhesive sheet having a conductive substrate 1 and a conductive adhesive agent layer 2, wherein the conductive adhesive agent layer 2 has a thickness of 20 μm or less and is composed of an acrylic adhesive agent composition containing an acrylic copolymer, a triazole-based compound, a crosslinking agent and a conductive particles, the acrylic copolymer contains a monomer containing a carboxyl group, and the content of the monomer containing a carboxyl group in the monomer components constituting the acrylic copolymer is 1 to 10 mass%.

Description

  The present invention relates to a conductive pressure-sensitive adhesive sheet having a conductive substrate and a pressure-sensitive adhesive layer containing conductive particles.

  Conductive adhesive sheet is easy to handle, shields unnecessary electromagnetic waves radiated from electricity and electronic equipment, shields harmful electromagnetic waves from other electrical and electronic equipment, and grounds for antistatic charge With the recent miniaturization and thinning of electrical and electronic equipment, conductive adhesive sheets used for these are also required to be thin.

  As a thin conductive pressure-sensitive adhesive sheet, a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer made of a conductive pressure-sensitive adhesive in which a conductive filler is dispersed in a pressure-sensitive adhesive material is disclosed on a conductive substrate (Patent Document 1). ~ 2). It is disclosed that these pressure-sensitive adhesive sheets have suitable conductivity and adhesiveness.

JP 2004-263030 A JP 2009-79127 A

  However, in response to the demand for further thinning in recent small electronic terminals and the like, when the pressure-sensitive adhesive sheet is an ultra-thin pressure-sensitive adhesive sheet, the adhesiveness is likely to be lowered, so that improvement of the adhesiveness has been demanded. . In particular, in a pressure-sensitive adhesive sheet using a conductive substrate, the adhesive force may be reduced during storage, and in a thin pressure-sensitive adhesive sheet in which it is difficult to secure the adhesive force, there may be a problem in adhesiveness.

  The problem to be solved by the present invention is to provide a conductive pressure-sensitive adhesive sheet that has good adhesiveness and conductivity even when it is thin, and is less likely to cause a decrease in adhesive strength over time.

In this invention, it is a conductive adhesive sheet which has a conductive base material and a conductive adhesive layer, Comprising: The thickness of a conductive adhesive layer is 20 micrometers or less, and a conductive adhesive layer is an acrylic copolymer. A monomer comprising an acrylic pressure-sensitive adhesive composition containing a triazole compound, a crosslinking agent and conductive particles, wherein the acrylic copolymer contains a monomer containing a carboxyl group. The content of the monomer containing a carboxyl group in the component is 1 to 10% by mass
The said subject was solved by the electroconductive adhesive sheet which is.

  The conductive thin pressure-sensitive adhesive sheet of the present invention has an excellent adhesion and conductivity to an adherend while being extremely thin, and is difficult to cause a decrease in adhesive force during storage. It is useful for shielding electromagnetic waves used in, etc., shielding harmful spatial electromagnetic waves generated from other electric and electronic devices, and grounding fixing for preventing static electricity. In particular, the present invention can be suitably applied to portable electronic device applications that are becoming thinner and have severe volume restrictions within the housing.

It is the schematic which shows the structural example of the electroconductive adhesive sheet of this invention. It is the schematic which shows the structural example of the electroconductive adhesive sheet of this invention. It is the schematic of the resilience evaluation method in an Example.

  The conductive pressure-sensitive adhesive sheet of the present invention is a conductive pressure-sensitive adhesive sheet having a conductive substrate and a conductive pressure-sensitive adhesive layer, wherein the thickness of the conductive pressure-sensitive adhesive layer is 20 μm or less, and the conductive pressure-sensitive adhesive layer is An acrylic copolymer comprising an acrylic pressure-sensitive adhesive composition containing an acrylic copolymer, a triazole compound, a crosslinking agent and conductive particles, the acrylic copolymer containing a carboxyl group-containing monomer as a monomer component, and an acrylic copolymer Is a conductive pressure-sensitive adhesive sheet in which the content of the carboxyl group-containing monomer in the monomer component constituting 1 is 1 to 10% by mass.

  Below, the electroconductive adhesive sheet of this invention is demonstrated in more detail based on the component. The “sheet” in the present invention means a form in which at least one thin layer of conductive adhesive is provided on a conductive substrate or a release sheet. For example, each sheet, a roll, or a thin plate All product forms such as strips and strips (tapes) are included.

(Conductive adhesive layer)
The conductive pressure-sensitive adhesive layer used in the conductive pressure-sensitive adhesive sheet of the present invention contains a triazole compound, a crosslinking agent, and conductive particles in an acrylic pressure-sensitive adhesive composition containing an acrylic copolymer containing a carboxyl group. It is an adhesive layer which consists of a made conductive adhesive composition.

(Acrylic copolymer)
As an acrylic copolymer, the acrylic copolymer which has a C1-C14 (meth) acrylate monomer as a main monomer component can be used preferably, As a C1-C14 (meth) acrylate, Methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, n-hexyl (meth) acrylate, n-octyl (meth) acrylate, Monomers such as isooctyl (meth) acrylate, isononyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and the like, and one or more of these are used. Among these, (meth) acrylates having 4 to 12 carbon atoms in the alkyl group are preferable, and (meth) acrylates having a linear or branched structure having 4 to 9 carbon atoms are more preferable. Of these, n-butyl acrylate and 2-ethylhexyl acrylate can be preferably used, and these may be used alone or in combination.

  The content of the (meth) acrylate having 1 to 14 carbon atoms in the acrylic copolymer is preferably 80 to 98.5% by mass in the monomer component constituting the acrylic copolymer, and is 90 to 98. More preferably, it is 5 mass%.

  The acrylic copolymer used in the present invention is also preferably copolymerized with a highly polar vinyl monomer. Examples of the highly polar vinyl monomer include a vinyl monomer having a carboxyl group, a vinyl monomer having a hydroxyl group, and a vinyl having an amide group. A monomer etc. are mentioned, These 1 type (s) or 2 or more types are used. Among these, a carboxyl group-containing monomer can be preferably used because it easily adjusts the adhesiveness of the pressure-sensitive adhesive to a suitable range.

  As the vinyl monomer having a carboxyl group, acrylic acid, methacrylic acid, itaconic acid, maleic acid, (meth) acrylic acid dimer, crotonic acid, ethylene oxide-modified succinic acid acrylate, etc. can be used, among which acrylic acid or methacrylic acid It is preferable to use an acid as a copolymerization component, and it is particularly preferable to use acrylic acid.

  Content of the vinyl monomer which has a carboxyl group is 1-10 mass% in the monomer component which comprises an acrylic copolymer. Among these, it is preferable that it is 1.5-6 mass%, More preferably, it is preferable that it is 2-4 mass%. By being the said range, it is easy to adjust the initial adhesiveness to a metal and the adhesiveness after high-temperature, high-humidity storage to a suitable range.

  Examples of the monomer having a hydroxyl group include hydroxyl groups such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate and the like ( A (meth) acrylate can be used.

  Examples of the monomer having an amide group include N-vinylpyrrolidone, N-vinylcaprolactam, acryloylmorpholine, acrylamide, and N, N-dimethylacrylamide.

  Other highly polar vinyl monomers include vinyl acetate, ethylene oxide modified succinic acid acrylate, sulfonic acid group-containing monomers such as 2-acrylamido-2-methylpropane sulfonic acid, 2-methoxyethyl (meth) acrylate, 2-phenoxyethyl ( And terminal alkoxy-modified (meth) acrylates such as (meth) acrylate.

  The content of the other highly polar vinyl monomer is preferably 0.2 to 15% by mass, and preferably 0.4 to 10% by mass in the monomer component constituting the acrylic copolymer. More preferably, it is more preferable that it is 0.5-6 mass%. By containing in the said range, it is easy to adjust the adhesiveness of an adhesive to a suitable range.

  The acrylic copolymer can be obtained by copolymerization by a known method such as a solution polymerization method, a bulk polymerization method, a suspension polymerization method, or an emulsion polymerization method. However, from the viewpoint of production cost and productivity, solution polymerization is possible. It is preferable to be polymerized by. The average molecular weight of the acrylic copolymer is preferably 300,000 to 1,500,000, more preferably 500,000 to 1,200,000.

(Additive)
Furthermore, in order to improve the adhesive strength of the conductive adhesive sheet, a tackifier resin may be added. Tackifying resins to be added to the conductive adhesive used in the present invention are rosin resins, terpene resins, aliphatic (C5) and aromatic (C9) petroleum resins, styrene resin phenolic resins, Examples include xylene resins and methacrylic resins. Among these, a rosin resin is preferable, and a polymerized rosin resin is particularly preferable. As addition amount of tackifying resin, it is preferable to add 10-50 mass parts with respect to 100 mass parts (solid content) of a (meth) acrylic-type copolymer.

  Various additives may be added to the pressure-sensitive adhesive used in the conductive pressure-sensitive adhesive sheet of the present invention, if necessary. As said additive, a plasticizer, a softener, a metal deactivator, antioxidant, a pigment, dye, etc. are mentioned, for example, It uses suitably as needed.

(Triazole compound)
The pressure-sensitive adhesive used for the conductive pressure-sensitive adhesive sheet of the present invention contains a triazole compound. Examples of the triazole compound include benzotriazole, tolyltriazole and its potassium salt, 3- (N-salicyloyl) amino-1,2,4 triazole, 2- (2′-hydroxy-5methylphenyl) benzotriazole and the like. Of these, benzotriazole is preferable because it has a high effect of preventing solubility and adhesive strength from decreasing.

  Although it does not specifically limit as content of a triazole type compound, 0.05-3.0 mass parts is preferable with respect to 100 mass parts (solid content) of an acrylic adhesive composition. Among these, 0.1 to 1.5 parts by mass is preferable, and 0.3 to 1.0 part by mass is most preferable. By setting it as the said content, it becomes easy to obtain especially suitable holding power, and it becomes easy to suppress especially the adhesive force fall after a high temperature, high humidity environment test.

(Crosslinking agent)
The acrylic pressure-sensitive adhesive composition used for the conductive pressure-sensitive adhesive sheet of the present invention contains a cross-linking agent, thereby improving the cohesive force by forming a three-dimensional cross-linked structure in the obtained conductive pressure-sensitive adhesive layer. . Examples of the formation of the crosslinked structure include known crosslinking agents such as isocyanate crosslinking agents, epoxy crosslinking agents, chelate crosslinking agents, and aziridine crosslinking agents. The type of the crosslinking agent is preferably selected according to the functional group of the monomer component described above.

  The addition amount of the crosslinking agent is preferably used in such an amount that the gel fraction of the obtained conductive pressure-sensitive adhesive layer is 25 to 65% by mass, more preferably 35 to 60% by mass, and most preferably It is 40-55 mass%. By setting the gel fraction within the above range, the cohesive force in the shearing direction and the peeling resistance can be improved.

The gel fraction is calculated by the following formula.
Gel fraction (% by mass) = {(Adhesive mass after being immersed in toluene) / (Adhesive mass before being immersed in toluene)} × 100

(Conductive particles)
The conductive particles used in the conductive adhesive sheet of the present invention are made of metal powder particles such as gold, silver, copper, nickel, and aluminum, conductive resins such as carbon and graphite, resin, solid glass beads, and hollow glass. Those having a metal coating on the surface of the beads can be used. Among these, nickel powder particles, copper powder particles, and silver powder particles are preferable because they are excellent in conductivity, adhesiveness, and productivity. More preferred are surface needle-shaped nickel particles having a large number of needle-like shapes on the surface of the particles produced by the carbonyl method, those obtained by smoothing the surface needle-shaped particles into spherical particles, Examples thereof include copper powder and silver powder produced by a high-pressure swirling water atomization method. Two or more kinds of these conductive particles may be mixed and used.

  The shape of the conductive particles is preferably a spherical shape or a surface needle shape. The aspect ratio is not particularly limited, but is preferably 1 to 2, more preferably 1 to 1.5, and most preferably 1 to 1.2. The aspect ratio can be measured with a scanning electron microscope.

The tap density of the conductive particles is not particularly limited, but 2 to 7 g / cm ³ is preferable because it does not easily settle or aggregate during production. More preferably from 3 to 6 g / cm ^3, and most preferably 4-5 g / cm ^3.

  The particle diameter of the conductive particles is not particularly limited, but it is preferable that the particle diameter d50 is 4 to 12 μm and the particle diameter d85 is 6 to 25 μm. d50 is more preferably 4 to 10 μm, further preferably 5 to 9 μm, and most preferably 6 to 8 μm. D85 is more preferably 6.5 to 14 μm, further preferably 7 to 13 μm, and most preferably 8 to 11 μm. In addition, when mixing 2 or more types of electroconductive particle, it is preferable that the particle diameters d50 and d85 after mixing are the said ranges.

  The particle diameter d50 is a 50% cumulative value (median diameter) in the particle size distribution. The particle diameter d85 is an 85% cumulative value. These particle sizes are values measured by a laser analysis / scattering method. Examples of the measuring device include Nikkiso Microtrack MT3000II, Shimadzu Laser Diffraction Particle Size Distribution Analyzer SALD-3000, and the like.

  The particle diameter d50 of the conductive particles is preferably 50 to 150% of the thickness of the pressure-sensitive adhesive layer, and d85 is preferably 80 to 200%. By using conductive particles in the above range, it is easy to achieve both conductivity, adhesion and productivity. d50 is more preferably 60 to 120%, and most preferably 70 to 100%. d85 is more preferably 100 to 150%, and more preferably 110 to 140%.

  Although it does not specifically limit as content of the electroconductive particle in an electroconductive adhesive layer, 10-100 mass parts is preferable with respect to 100 mass parts (solid content) of an acrylic adhesive composition, More preferably, it is 20-80 mass parts, More preferably, it is 30-70 mass parts, and 40-60 mass parts is the most preferable. By making content of electroconductive particle into the said range, it becomes easy to make electroconductivity, adhesiveness, and productivity compatible.

  Examples of the method for dispersing the conductive particles in the acrylic pressure-sensitive adhesive composition include a method of dispersing an acrylic copolymer, a solvent, conductive particles, additives, and the like with a dispersion stirrer. Examples of the commercially available dispersion stirrer include a dissolver manufactured by Inoue Seisakusho, a butterfly mixer, a BDM biaxial mixer, and a planetary mixer. Among them, a dissolver or a butterfly mixer that can apply a medium share with little thickening of the pressure-sensitive adhesive during stirring is preferable.

  Although it does not specifically limit as solid content of an acrylic adhesive composition, 10 to 70% is preferable, More preferably, it is 30 to 55%, Most preferably, it is 43 to 50%.

(Thickness of conductive adhesive layer)
The thickness of the pressure-sensitive adhesive layer of the conductive pressure-sensitive adhesive sheet is 20 μm or less. Preferably it is 1-16 micrometers, and it is especially preferable that it is 3-12 micrometers among them. When it is in the above range, both adhesiveness and thinness can be achieved.

(Conductive substrate)
Examples of the conductive substrate used in the conductive adhesive sheet of the present invention include a metal foil substrate and a graphite substrate. Examples of the material of the metal foil include gold, silver, copper, aluminum, nickel, iron, tin, and alloys thereof. Among these, a conductive base material containing copper is preferable, and a copper foil is more preferable in terms of conductivity, workability, and cost. More preferably, a rolled copper foil having excellent flexibility is preferable.

  Further, the copper foil is preferably subjected to a rust prevention treatment. Examples of the rust prevention treatment include organic rust prevention and inorganic rust prevention. Among them, inorganic rust prevention by chromate treatment is most preferable. Examples of commercially available electrolytic copper foils include CF-T9FZ-HS-9 (9 μm: chromate treatment) and CF-T9FZ-HS-9 (9 μm: chromate treatment) manufactured by Fukuda Metal Foil Industry Co., Ltd. Examples of commercially available rolled copper foils include TCU-H-8-RT (8 μm: organic rust prevention treatment) manufactured by Nippon Foil Co., Ltd., BAY-64T-DT (35 μm: chromate treatment) manufactured by JX Nippon Mining & Metals. It is done.

  As thickness of a conductive base material, 1-40 micrometers is preferable, More preferably, it is 3-16 micrometers, Most preferably, it is 6-12 micrometers. If it is the said range, since thickness reduction is possible and it is excellent in workability, it is preferable.

(Release liner)
In the conductive pressure-sensitive adhesive sheet of the present invention, a release liner can be laminated on the pressure-sensitive adhesive layer. The release liner is not particularly limited. For example, paper such as kraft paper, glassine paper, and high-quality paper, resin films such as polyethylene, polypropylene (OPP, CPP), and polyethylene terephthalate, and laminates obtained by laminating the papers and resin films. Conventionally known papers such as paper, papers that have been subjected to sealing treatment with clay, polyvinyl alcohol, etc., and one side or both sides that have been subjected to a release treatment such as silicon-based resin can be used.

(Configuration of conductive adhesive sheet)
The electroconductive adhesive sheet of this invention is an electroconductive adhesive sheet which has the said electroconductive adhesive layer and an electroconductive base material. The conductive pressure-sensitive adhesive sheet of the present invention has a low adhesive strength even after being left at high temperature and high humidity while being thin, and the above-mentioned conductive pressure-sensitive adhesive layer is used as a pressure-sensitive adhesive layer that can meet the demand for thinning of portable electronic devices and the like. By using it, it is possible to realize good adhesion, conductivity, and stability over time.

  The total thickness of the conductive adhesive sheet is preferably 85 μm or less, more preferably 50 μm or less, and particularly preferably 30 μm or less. By being in the said range, thickness reduction of an adhesive sheet can be achieved, ensuring adhesiveness and electroconductivity, and it can contribute to thickness reduction of a portable electronic device. The total thickness of the conductive adhesive sheet is the thickness of the conductive adhesive sheet itself that does not include a release liner.

  The example of the suitable structure of the electroconductive adhesive sheet of this invention is shown in FIG.1 and FIG.2. FIG. 1 is a single-sided pressure-sensitive adhesive sheet in which a conductive pressure-sensitive adhesive layer 2 is laminated on a conductive substrate 1. FIG. 2 shows a double-sided pressure-sensitive adhesive sheet in which a conductive pressure-sensitive adhesive layer 2 is laminated on both surfaces of a conductive substrate 1. In these configurations, a configuration in which a release liner is provided on the surface of the pressure-sensitive adhesive layer 2 can be preferably used.

  The conductive thin pressure-sensitive adhesive sheet of the present invention has an excellent adhesion and conductivity to an adherend while being extremely thin, and is difficult to cause a decrease in adhesive force during storage. It is useful for shielding electromagnetic waves used in, etc., shielding harmful spatial electromagnetic waves generated from other electric and electronic devices, and grounding fixing for preventing static electricity. In particular, it can be suitably applied to applications that are used by being attached to a built-in component of a small electronic terminal such as a portable electronic device that is becoming thinner and has a severe volume limit within the housing.

  Examples will be specifically described below, but the present invention is not limited to these examples.

(Adjustment of acrylic adhesive composition)

[Preparation of acrylic pressure-sensitive adhesive composition (1)]
In a reaction vessel equipped with a condenser, a stirrer, a thermometer, and a dropping funnel, 96.4 parts by mass of n-butyl acrylate, 0.1 part by mass of 2-hydroxyethyl acrylate, 3.5 parts by mass of acrylic acid and a polymerization initiator 0.1 part by mass of 2,2′-azobisisobutylnitrile is dissolved in 100 parts by mass of ethyl acetate, and after substitution with nitrogen, polymerization is carried out at 80 ° C. for 12 hours to obtain an acrylic copolymer having a mass average molecular weight of 600,000. It was. For 100 parts by mass of the solid content of this acrylic copolymer solution, 10 parts by mass of polymerized rosin pentaerythritol ester (Arakawa Chemical Co., Ltd., Pencel D-135, softening point 135 ° C.), disproportionated rosin glycerin ester ( Arakawa Chemical Co., Ltd., Super Ester A-100, softening point 100 ° C.) 10 parts by mass, adjusting the resin solids concentration to 45% by mass with ethyl acetate, acrylic pressure-sensitive adhesive composition (1) Adjusted.

[Preparation of acrylic pressure-sensitive adhesive composition (2)]
In a reaction vessel equipped with a condenser, a stirrer, a thermometer, and a dropping funnel, 96.9 parts by mass of n-butyl acrylate, 0.1 part by mass of 2-hydroxyethyl acrylate, 3.0 parts by mass of acrylic acid and a polymerization initiator 0.1 part by mass of 2,2′-azobisisobutylnitrile is dissolved in 100 parts by mass of ethyl acetate, and after substitution with nitrogen, polymerization is carried out at 80 ° C. for 12 hours to obtain an acrylic copolymer having a mass average molecular weight of 600,000. It was. For 100 parts by mass of the solid content of this acrylic copolymer solution, 10 parts by mass of polymerized rosin pentaerythritol ester (Arakawa Chemical Co., Ltd., Pencel D-135, softening point 135 ° C.), disproportionated rosin glycerin ester ( Arakawa Chemical Co., Ltd., Super Ester A-100, softening point 100 ° C.) 10 parts by mass, adjusting the resin solids concentration to 45% by mass with ethyl acetate, acrylic pressure-sensitive adhesive composition (2) Adjusted.

[Preparation of acrylic pressure-sensitive adhesive composition (3)]
In a reaction vessel equipped with a condenser, a stirrer, a thermometer, and a dropping funnel, 97.9 parts by mass of n-butyl acrylate, 0.1 part by mass of 2-hydroxyethyl acrylate, 2.0 parts by mass of acrylic acid and a polymerization initiator 0.1 part by mass of 2,2′-azobisisobutylnitrile is dissolved in 100 parts by mass of ethyl acetate, and after substitution with nitrogen, polymerization is carried out at 80 ° C. for 12 hours to obtain an acrylic copolymer having a mass average molecular weight of 600,000. It was. For 100 parts by mass of the solid content of this acrylic copolymer solution, 10 parts by mass of polymerized rosin pentaerythritol ester (Arakawa Chemical Co., Ltd., Pencel D-135, softening point 135 ° C.), disproportionated rosin glycerin ester ( Arakawa Chemical Co., Ltd., Super Ester A-100, softening point 100 ° C.) 10 parts by mass, adjusting the resin solids concentration to 45% by mass with ethyl acetate, acrylic pressure-sensitive adhesive composition (3) Adjusted.

[Preparation of acrylic pressure-sensitive adhesive composition (4)]
As a polymerization initiator, 99.4 parts by mass of n-butyl acrylate, 0.1 part by mass of 2-hydroxyethyl acrylate, 0.5 part by mass of acrylic acid, and a reaction vessel equipped with a condenser, a stirrer, a thermometer, and a dropping funnel 0.1 part by mass of 2,2′-azobisisobutylnitrile is dissolved in 100 parts by mass of ethyl acetate, and after substitution with nitrogen, polymerization is carried out at 80 ° C. for 12 hours to obtain an acrylic copolymer having a mass average molecular weight of 600,000. It was. For 100 parts by mass of the solid content of this acrylic copolymer solution, 10 parts by mass of polymerized rosin pentaerythritol ester (Arakawa Chemical Co., Ltd., Pencel D-135, softening point 135 ° C.), disproportionated rosin glycerin ester ( Arakawa Chemical Co., Ltd., Super Ester A-100, softening point 100 ° C.) 10 parts by mass, adjusting the resin solids concentration to 45% by mass with ethyl acetate, acrylic pressure-sensitive adhesive composition (4) Adjusted.

[Preparation of acrylic pressure-sensitive adhesive composition (5)]
In a reaction vessel equipped with a condenser, a stirrer, a thermometer, and a dropping funnel, 99.9 parts by mass of n-butyl acrylate, 0.1 part by mass of 2-hydroxyethyl acrylate, and 2,2′-azobisisobutyl as a polymerization initiator 0.1 part by mass of nitrile was dissolved in 100 parts by mass of ethyl acetate, purged with nitrogen, and then polymerized at 80 ° C. for 12 hours to obtain an acrylic copolymer having a mass average molecular weight of 600,000. For 100 parts by mass of the solid content of this acrylic copolymer solution, 10 parts by mass of polymerized rosin pentaerythritol ester (Arakawa Chemical Co., Ltd., Pencel D-135, softening point 135 ° C.), disproportionated rosin glycerin ester ( Arakawa Chemical Co., Ltd., Super Ester A-100, softening point 100 ° C.) 10 parts by mass, adjusting the resin solids concentration to 45% by mass with ethyl acetate, acrylic pressure-sensitive adhesive composition (5) Adjusted.

(Preparation of conductive adhesive composition)
[Preparation of conductive adhesive composition (1A)]
Nickel powder NI123J (d50: 6.3 μm, d85: 10.0 μm, tap density) manufactured by Fukuda Metal Foil Powder Industry Co., Ltd. with respect to 100 parts by mass (solid content: 45 parts by mass) of the acrylic pressure-sensitive adhesive composition (1). 4.3 g / cm ³ , smoothed Inco Ltd. NI123) 22.5 parts by mass, cross-linking agent Barnock NC40 (DIC-based isocyanate cross-linking agent, solid content 40% by mass) 2.5 parts by mass, 0.23 parts by mass of benzotriazole was blended, the solid content concentration was adjusted to 47% by mass with ethyl acetate, and the mixture was mixed with a dispersion stirrer for 10 minutes to prepare a conductive adhesive 1A.

[Preparation of conductive adhesive composition (1B)]
Nickel powder NI123J (d50: 6.3 μm, d85: 10.0 μm, tap density) manufactured by Fukuda Metal Foil Powder Industry Co., Ltd. with respect to 100 parts by mass (solid content: 45 parts by mass) of the acrylic pressure-sensitive adhesive composition (1). 4.3 g / cm ³ , smoothed Inco Ltd NI123) 22.5 parts by mass, crosslinker Vernock NC40 (DIC crosslinker made by DIC, solid content 40% by mass) 2.0 parts by mass, 0.23 parts by mass of benzotriazole was blended, the solid content concentration was adjusted to 47% by mass with ethyl acetate, and the mixture was mixed with a dispersion stirrer for 10 minutes to prepare a conductive adhesive (1B).

[Preparation of conductive adhesive composition (1C)]
Nickel powder NI123J (d50: 6.3 μm, d85: 10.0 μm, tap density) manufactured by Fukuda Metal Foil Powder Industry Co., Ltd. with respect to 100 parts by mass (solid content: 45 parts by mass) of the acrylic pressure-sensitive adhesive composition (1). 4.3 g / cm ³ , smoothed Inco Ltd. NI123) 22.5 parts by mass, cross-linking agent Barnock NC40 (DIC-based isocyanate cross-linking agent, solid content 40% by mass) 2.5 parts by mass, 1.0 mass part of benzotriazole was mix | blended, solid content concentration was adjusted to 47 mass% with ethyl acetate, and it mixed for 10 minutes with the dispersion stirrer, and produced the electroconductive adhesive (1C).

[Preparation of conductive adhesive composition (1D)]
Nickel powder NI123J (d50: 6.3 μm, d85: 10.0 μm, tap density) manufactured by Fukuda Metal Foil Powder Industry Co., Ltd. with respect to 100 parts by mass (solid content: 45 parts by mass) of the acrylic pressure-sensitive adhesive composition (1). 4.3 g / cm ³ , smoothed Inco Ltd NI123) 22.5 parts by mass, crosslinker Vernock NC40 (DIC crosslinker made by DIC, solid content 40% by mass) 2.0 parts by mass, 0.5 parts by mass of benzotriazole was blended, the solid content concentration was adjusted to 47% by mass with ethyl acetate, and the mixture was mixed for 10 minutes with a dispersion stirrer to prepare a conductive adhesive (1D).

[Preparation of conductive adhesive composition (1E)]
Nickel powder NI123J (d50: 6.3 μm, d85: 10.0 μm, tap density) manufactured by Fukuda Metal Foil Powder Industry Co., Ltd. with respect to 100 parts by mass (solid content: 45 parts by mass) of the acrylic pressure-sensitive adhesive composition (1). 4.3 g / cm ³ , smoothed Inco Ltd NI123) 13.5 parts by mass, crosslinker Vernock NC40 (DIC crosslinker made by DIC, solid content 40% by mass) 2.0 parts by mass, 0.23 parts by mass of benzotriazole was blended, the solid content concentration was adjusted to 47% by mass with ethyl acetate, and the mixture was mixed for 10 minutes with a dispersion stirrer to prepare a conductive adhesive (1E).

[Preparation of conductive adhesive composition (1F)]
Nickel powder NI123J (d50: 6.3 μm, d85: 10.0 μm, tap density) manufactured by Fukuda Metal Foil Powder Industry Co., Ltd. with respect to 100 parts by mass (solid content: 45 parts by mass) of the acrylic pressure-sensitive adhesive composition (1). 4.3 g / cm ³ , smoothed Inco Ltd. NI123) 4.5 parts by mass, cross-linking agent Barnock NC40 (DIC-based isocyanate cross-linking agent, solid content 40% by mass) 2.0 parts by mass, 0.23 parts by mass of benzotriazole was blended, the solid content concentration was adjusted to 47% by mass with ethyl acetate, and the mixture was mixed for 10 minutes with a dispersion stirrer to prepare a conductive adhesive (1F).

[Preparation of conductive adhesive composition (1G)]
Nickel powder NI123 (d50: 10.3 μm, d85: 22 μm, tap density: 3.5 g / cm) manufactured by Incori Ltd. for 100 parts by weight (45 parts by weight of solid content) of the acrylic pressure-sensitive adhesive composition (1). ³ ) 22.5 parts by mass, 2.0 parts by mass of crosslinker Vernock NC40 (DIC isocyanate crosslinker, solid content 40% by mass) were blended, and the solid content concentration was adjusted to 47% by mass with ethyl acetate. The mixture was mixed with a dispersion stirrer for 10 minutes to prepare a conductive adhesive (1G).

[Preparation of conductive adhesive composition (1H)]
Nickel powder NI123J (d50: 6.3 μm, d85: 10.0 μm, tap density) manufactured by Fukuda Metal Foil Powder Industry Co., Ltd. with respect to 100 parts by mass (solid content: 45 parts by mass) of the acrylic pressure-sensitive adhesive composition (1). 4.3 g / cm ³ , smoothed Inco Ltd. NI123) 22.5 parts by mass, crosslinking agent Barnock NC40 (DIC-based isocyanate crosslinking agent, solid content 40% by mass) 2.0 parts by mass The mixture was mixed, the solid content concentration was adjusted to 47% by mass with ethyl acetate, and the mixture was mixed with a dispersion stirrer for 10 minutes to prepare a conductive adhesive (1H).

[Preparation of conductive adhesive composition (2)]
Nickel powder NI123J (d50: 6.3 μm, d85: 10.0 μm, tap density: manufactured by Fukuda Metal Foil Powder Industry Co., Ltd.) with respect to 100 parts by mass (solid content: 45 parts by mass) of the acrylic pressure-sensitive adhesive composition (2) 4.3 g / cm ³ , smoothed Inco Ltd. NI123) 22.5 parts by mass, cross-linking agent Barnock NC40 (DIC-based isocyanate cross-linking agent, solid content 40% by mass) 2.5 parts by mass, 0.23 parts by mass of benzotriazole was blended, the solid content concentration was adjusted to 47% by mass with ethyl acetate, and the mixture was mixed with a dispersion stirrer for 10 minutes to prepare a conductive adhesive (2).

[Preparation of conductive adhesive composition (3)]
Nickel powder NI123J (d50: 6.3 μm, d85: 10.0 μm, tap density: manufactured by Fukuda Metal Foil Powder Industry Co., Ltd.) with respect to 100 parts by mass (solid content: 45 parts by mass) of the acrylic pressure-sensitive adhesive composition (3). 4.3 g / cm ³ , smoothed Inco Ltd. NI123) 22.5 parts by mass, cross-linking agent Barnock NC40 (DIC-based isocyanate cross-linking agent, solid content 40% by mass) 2.5 parts by mass, 0.1 parts by mass of benzotriazole was blended, the solid content concentration was adjusted to 47% by mass with ethyl acetate, and the mixture was mixed for 10 minutes with a dispersion stirrer to prepare a conductive adhesive (3).

[Preparation of conductive adhesive composition (4)]
Nickel powder NI123J (d50: 6.3 μm, d85: 10.0 μm, tap density: manufactured by Fukuda Metal Foil Powder Co., Ltd.) with respect to 100 parts by mass (solid content: 45 parts by mass) of the acrylic pressure-sensitive adhesive composition (4). 4.3 g / cm ³ , smoothed Inco Ltd. NI123) 22.5 parts by mass, crosslinking agent Barnock NC40 (DIC-based isocyanate crosslinking agent, solid content 40% by mass) 2.0 parts by mass It mix | blended, solid content concentration was adjusted to 47 mass% with ethyl acetate, and it mixed for 10 minutes with the dispersion stirrer, and produced the electroconductive adhesive (4).

[Preparation of conductive adhesive composition (5)]
Nickel powder NI123J (d50: 6.3 μm, d85: 10.0 μm, tap density) manufactured by Fukuda Metal Foil Powder Industry Co., Ltd. with respect to 100 parts by mass (solid content: 45 parts by mass) of the acrylic pressure-sensitive adhesive composition (5). 4.3 g / cm ³ , smoothed Inco Ltd. NI123) 22.5 parts by mass, crosslinking agent Barnock NC40 (DIC-based isocyanate crosslinking agent, solid content 40% by mass) 2.0 parts by mass It mix | blended, solid content concentration was adjusted to 47 mass% with ethyl acetate, it mixed for 10 minutes with the dispersion stirrer, and the electroconductive adhesive (5) was created.

Example 1
[Creation of conductive adhesive sheet]
The conductive pressure-sensitive adhesive composition (1A) was coated on a release film “PET38 × 1 A3” manufactured by Nippa with a comma coater so that the thickness of the pressure-sensitive adhesive layer after drying was 10 μm, and a dryer at 80 ° C. After being dried for 2 minutes, after being bonded to both sides of an electrolytic copper foil (CF-T9FZ-SV, manufactured by Fukuda Metal Foil Co., Ltd.) having a thickness of 9 μm treated with inorganic rust (chromate), the temperature is 40 ° C. After curing for 48 hours, the conductive adhesive sheet of Example 1 was prepared.

(Example 2)
Example similar to Example 1 except that an organic rust-proof rolled copper foil (TCU-H-8) was used instead of the inorganic (chromate) rust-proof electrolytic copper foil (CF-T9FZ-SV) 2 conductive adhesive sheets were prepared.

(Example 3)
A conductive pressure-sensitive adhesive sheet of Example 3 was prepared in the same manner as in Example 1 except that the conductive pressure-sensitive adhesive composition (1B) was used instead of the conductive pressure-sensitive adhesive composition (1A).

(Example 4)
A conductive pressure-sensitive adhesive sheet of Example 4 was prepared in the same manner as in Example 1 except that the conductive pressure-sensitive adhesive composition (1C) was used instead of the conductive pressure-sensitive adhesive composition (1A).

(Example 5)
A conductive pressure-sensitive adhesive sheet of Example 5 was prepared in the same manner as in Example 1 except that the conductive pressure-sensitive adhesive composition (1D) was used instead of the conductive pressure-sensitive adhesive composition (1A).

(Example 6)
A conductive pressure-sensitive adhesive sheet of Example 6 was prepared in the same manner as in Example 1 except that the conductive pressure-sensitive adhesive composition (2) was used instead of the conductive pressure-sensitive adhesive composition (1A).

(Example 7)
A conductive pressure-sensitive adhesive sheet of Example 7 was prepared in the same manner as in Example 1 except that the conductive pressure-sensitive adhesive composition (3) was used instead of the conductive pressure-sensitive adhesive composition (1A).

(Example 8)
A conductive pressure-sensitive adhesive sheet of Example 8 was prepared in the same manner as in Example 1 except that the conductive pressure-sensitive adhesive composition (1E) was used instead of the conductive pressure-sensitive adhesive composition (1A).

Example 9
A conductive pressure-sensitive adhesive sheet of Example 9 was prepared in the same manner as in Example 1 except that the conductive pressure-sensitive adhesive composition (1F) was used instead of the conductive pressure-sensitive adhesive composition (1A).

(Example 10)
A conductive pressure-sensitive adhesive sheet of Example 10 was prepared in the same manner as in Example 1 except that the conductive pressure-sensitive adhesive composition (1G) was used instead of the conductive pressure-sensitive adhesive composition (1A).

(Example 11)
The conductive adhesive of Example 11 as in Example 1 except that the conductive adhesive composition (1G) was used instead of the conductive adhesive composition (1A) and the adhesive thickness was changed to 15 μm instead of 10 μm. Created a sheet.

(Comparative Example 1)
A conductive pressure-sensitive adhesive sheet of Comparative Example 1 was prepared in the same manner as in Example 2 except that the conductive pressure-sensitive adhesive composition (1H) was used instead of the conductive pressure-sensitive adhesive composition (1A).

(Comparative Example 2)
A conductive adhesive sheet of Comparative Example 2 was prepared in the same manner as Comparative Example 1 except that the thickness of the adhesive was 20 μm instead of 10 μm.

(Comparative Example 3)
A conductive pressure-sensitive adhesive sheet of Comparative Example 3 was prepared in the same manner as in Example 1 except that the conductive pressure-sensitive adhesive composition (1H) was used instead of the conductive pressure-sensitive adhesive composition (1A).

(Comparative Example 4)
A conductive pressure-sensitive adhesive sheet of Comparative Example 4 was prepared in the same manner as in Example 2 except that the conductive pressure-sensitive adhesive composition (4) was used instead of the conductive pressure-sensitive adhesive composition (1A) and the curing was carried out at 40 ° C. for 120 hours. did.

(Comparative Example 5)
A conductive pressure-sensitive adhesive sheet of Comparative Example 5 was prepared in the same manner as in Example 2 except that the conductive pressure-sensitive adhesive composition (5) was used instead of the conductive pressure-sensitive adhesive composition (1A) and the curing was carried out at 40 ° C. for 120 hours. did.

(Evaluation)
The following evaluation was performed about the conductive adhesive sheet created in Examples 1-11 and Comparative Examples 1-5, and the obtained result was shown to the following table. In addition, the acrylic acid amount in a table | surface represents content (mass%) of acrylic acid in the monomer component which comprises an acryl-type copolymer. The amount of benzotriazole in the table represents the solid content (parts by mass) of benzotriazole with respect to 100 parts by mass of the solid content of the pressure-sensitive adhesive composition, and the amount of metal powder is 100 parts by mass of the solid content of the pressure-sensitive adhesive composition. Represents the content (parts by mass) of the metal powder with respect to.

[Particle size]
The particle diameter of the conductive particles was measured with a laser diffraction particle size distribution analyzer SALD-3000 manufactured by Shimadzu Corporation using isopropanol as a dispersion medium.

[Conductivity]
One surface of a 30 mm wide × 30 mm wide adhesive sheet is attached to a 25 mm × 25 mm brass electrode. A copper foil (thickness: 35 μm) of 30 mm × 80 mm is attached to the other surface of the test piece. A terminal is connected to the brass electrode and copper foil while applying a surface pressure of 20 N from above the brass electrode, and a current of 10 μA in a milliohm meter (made by NF circuit design) in an environment of 23 ° C. and 50% RH. The resistance value when flowing was measured.
The case of 500 mΩ or less was regarded as acceptable.

[Thickness (adhesive sheet)]
The thickness of the adhesive sheet was measured with a thickness meter “TH-102” manufactured by Tester Sangyo Co., Ltd.

[Thickness (adhesive layer)]
In the adhesive layer on the release film formed in the same manner as in the above Examples and Comparative Examples, a sample lined with PET 25 μm (S25 manufactured by Unitika Co., Ltd.) was prepared, and a thickness meter “TH-102” manufactured by Tester Sangyo Co., Ltd. was used. The thickness of the sample was measured, and the thickness of the pressure-sensitive adhesive layer was obtained by reducing the thickness of the release film and the backed PET.

[Adhesive strength]
A 20 mm wide conductive adhesive sheet sample was applied to a stainless steel plate (hereinafter referred to as a stainless steel plate) that had been subjected to hairline polishing treatment using No. 360 water-resistant polishing paper, and a 2.0 kg roller was reciprocatingly applied under a pressure of 23 ° C. and 50% RH. After leaving at room temperature for 1 hour, 180 ° peel adhesion was measured at room temperature at a tensile rate of 300 mm / min with a tensile tester (Tensilon RTA-100, manufactured by A & D). The double-sided PSA sheet was measured by backing PET 25 μm (S25 manufactured by Unitika) on the opposite side of the measurement surface.
In addition, the adhesive force of the electroconductive adhesive sheet was implemented on both sides, and the value on the lower side was described.

[Adhesive strength after standing]
The conductive adhesive sheet sample was allowed to stand at 60 ° C. and 90% RH for 200 hours with a release film on both sides. Thereafter, the adhesive strength of the sample was measured according to the adhesive strength test.
In addition, the adhesive force of the electroconductive adhesive sheet was implemented on both sides, and the value on the lower side was described.

[Retention force]
A conductive adhesive sheet sample cut to a width of 20 mm was affixed to a stainless steel plate, a load of 100 g (20 mm × 20 mm) was applied in the vertical direction according to JIS Z0237, and the drop time was measured in an atmosphere of 100 ° C.

[Rebound resistance after standing]
The conductive adhesive sheet sample was allowed to stand at 60 ° C. and 90% RH for 200 hours with a release film on both sides. Thereafter, as shown in FIG. 3, a 100 μm PET film 4 (Unite Emblet SA # 100) and a 2 mm thick stainless steel plate 5 were fixed with a fixing tape 6, and then the end portion of the folded PET film 4 and the stainless steel plate were fixed. The plate 5 is pasted with a conductive adhesive sheet 3 of 5 mm × 20 mm. Then, pressurization is performed under the condition of one reciprocation of a 2 kg roller, and the floating peeling after standing at 85 ° C. for 72 hours is observed. When the float of 2 mm or more occurs, it is not suitable for a small electronic terminal application having a severe thickness difference.
◎: Floating peeling is less than 0.5 mm ○: Floating peeling is 0.5 mm or more and less than 2 mm △: Floating peeling is 2 mm or more ×: Whole surface peeling

  As is clear from the above table, the pressure-sensitive adhesive sheets of Examples 1 to 11 of the present invention did not decrease in adhesive force and had good resilience even when left under high temperature and high humidity. On the other hand, although the adhesive sheets of Comparative Examples 1 to 3 had good initial adhesive strength, the adhesive strength when left under high temperature and high humidity was significantly reduced. The adhesive sheets of Comparative Examples 4 and 5 had low initial adhesive strength and were inferior in resilience resistance.

DESCRIPTION OF SYMBOLS 1 Conductive base material 2 Conductive adhesive layer 25 Conductive adhesive tape 20 Fixing tape 23 Stainless steel plate 24 PET film

Claims (9)

A conductive pressure-sensitive adhesive sheet having a conductive substrate and a conductive pressure-sensitive adhesive layer,
The conductive adhesive layer has a thickness of 20 μm or less,
The conductive pressure-sensitive adhesive layer comprises an acrylic pressure-sensitive adhesive composition containing an acrylic copolymer, a triazole-based compound, a crosslinking agent, and conductive particles,
The acrylic copolymer contains a monomer containing a carboxyl group, and the content of the monomer containing a carboxyl group in the monomer component constituting the acrylic copolymer is 1 to 10% by mass. Conductive adhesive sheet. The conductive pressure-sensitive adhesive sheet according to claim 1, wherein a particle diameter d50 of the conductive particles is 4 to 12 µm, and d85 is 6 to 15 µm. Content of the electroconductive particle in the said electroconductive adhesive layer is 10-100 mass parts with respect to 100 mass parts (solid content) of an acrylic adhesive composition, The electroconductivity of Claim 1 or 2 Adhesive sheet. The content of the triazole compound in the pressure-sensitive adhesive composition is 0.05 to 3.0 parts by mass with respect to 100 parts by mass (solid content) of the acrylic pressure-sensitive adhesive composition. The conductive adhesive sheet according to 1. The conductive adhesive sheet according to any one of claims 1 to 4, wherein the conductive adhesive layer has a gel fraction of 25 to 65 mass%. The conductive adhesive sheet according to claim 1, wherein the conductive substrate is a conductive substrate containing copper. The conductive adhesive sheet according to any one of claims 1 to 6, wherein the conductive substrate is a copper foil substrate subjected to an inorganic rust prevention treatment. The conductive adhesive sheet according to any one of claims 1 to 7, wherein the sticking area is 10 mm x 50 mm or less. The conductive adhesive sheet according to any one of claims 1 to 8, which is used by being attached to a built-in component of a small electronic terminal.

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