JP6798646B2 - Conductive adhesive sheet - Google Patents

Description

The present invention relates to a conductive pressure-sensitive adhesive sheet having a conductive pressure-sensitive adhesive layer.

Due to its ease of handling, the conductive adhesive sheet is used to shield unnecessary leaked electromagnetic waves radiated from electrical and electronic devices, to shield harmful spatial electromagnetic waves generated by other electrical and electronic devices, and to prevent static electricity from being grounded. It is used for various purposes, and with the recent miniaturization and thinning of electrical and electronic devices, the conductive adhesive sheet used for these is also required to be thinned.

As the 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 material is disclosed on a conductive base material (Patent Documents 1 to 1). 2). It is disclosed that these pressure-sensitive adhesive sheets have suitable conductivity and adhesiveness.

However, with a conductive adhesive sheet using a conductive base material such as metal foil, the step followability is low when the electronic substrate has irregularities or when rigid bodies are bonded to each other, and air entrainment and peeling from the adherend are prevented. Since it is generated, there is a problem that the conductivity becomes unstable (Patent Document 1). On the other hand, the conventional base material-less type conductive pressure-sensitive adhesive sheet that does not use a conductive base material has a problem that it has excellent followability to unevenness but low conductivity in the plane direction of the tape.

Japanese Unexamined Patent Publication No. 2004-263030

The problems to be solved by the present invention are good adhesiveness and conductivity in the thickness direction (Z-axis direction) and the plane direction (XY direction) of the tape even in the uneven portion of the electronic substrate or when the rigid bodies are bonded to each other. It is an object of the present invention to provide a conductive pressure-sensitive adhesive sheet having property and step-following property.

In the present invention, it is a conductive pressure-sensitive adhesive sheet having a conductive pressure-sensitive adhesive layer, and the conductive pressure-sensitive adhesive layer contains at least one kind of conductive particles, and the shape of the conductive particles is scaly or flake-shaped. Alternatively, when the surface that is plate-shaped and has the largest area in the shape of the conductive particles is the main surface, the thickness with respect to the main surface is 0.5 to 6.0 μm, and the thickness of the conductive particles. By the conductive pressure-sensitive adhesive sheet, the ratio of the average diameter of the main surface to the surface is 10 to 100, and the content of the conductive particles is 25 to 300% by mass with respect to the pressure-sensitive adhesive in the conductive pressure-sensitive adhesive layer. The above problem has been solved.

Although the conductive thin adhesive sheet of the present invention is thin, it has good adhesiveness and conductivity to an adherend, so that it is generated inside an electric or electronic device and is generated at another location of the electronic device or the like. For shielding (internal) electromagnetic waves that affect operation, for shielding harmful space (external) electromagnetic waves generated from other electrical or electronic devices and entering from the outside of electronic devices, etc., for grounding and fixing to prevent static electricity Useful as (for grounding). In particular, it can be suitably applied to portable electronic device applications in which the volume is limited in the housing due to the progress of thinning.

Since it is composed of only the conductive adhesive layer, it can adhere to the uneven part of the electronic substrate or even when the rigid bodies are bonded to each other by following the step of the adherend, so that it has good adhesiveness and conductivity. It is possible.

The conductive pressure-sensitive adhesive sheet of the present invention is a conductive pressure-sensitive adhesive sheet having a conductive pressure-sensitive adhesive layer, and the conductive pressure-sensitive adhesive layer contains at least one kind of conductive particles, and the shape of the conductive particles is scaly. When the surface having the largest area in the shape of the conductive particles is the main surface, the thickness with respect to the main surface is 0.5 to 6.0 μm, and the conductive particles have a shape, flakes, or plates. The ratio of the average diameter of the main surface to the thickness of the sex particles is 10 to 100, and the content of the conductive particles is 25 to 300% by mass with respect to the pressure-sensitive adhesive in the conductive pressure-sensitive adhesive layer. It is an adhesive sheet.

Hereinafter, the conductive pressure-sensitive adhesive sheet of the present invention will be described in more detail based on its components. The "sheet" in the present invention means a form in which at least one thin layer of a conductive pressure-sensitive adhesive is provided on a conductive base material or a release sheet, and for example, every leaf, roll, or thin plate. Includes all product forms such as shape and strip (tape).

(Conductive adhesive layer)
As the pressure-sensitive adhesive component constituting the conductive pressure-sensitive adhesive layer in the conductive pressure-sensitive adhesive sheet of the present invention, for example, an acrylic pressure-sensitive adhesive, a rubber-based pressure-sensitive adhesive, a silicone-based pressure-sensitive adhesive, or the like can be used. It is preferable to use.
Examples of the acrylic pressure-sensitive adhesive include an acrylic polymer and, if necessary, an acrylic pressure-sensitive adhesive containing a cross-linking agent and a tack-imparting resin.

As the acrylic polymer, for example, an acrylic containing a structural unit derived from n-butyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isononyl (meth) acrylate, ethyl (meth) acrylate and the like. A polymer can be used. Among them, as the acrylic polymer, it is preferable to use an acrylic polymer having a structural unit derived from a (meth) acrylic acid ester having an alkyl group having 2 to 14 carbon atoms, and n-butyl acrylate or 2 -Using an acrylic polymer containing a structural unit derived from ethylhexyl acrylate forms a conductive pressure-sensitive adhesive layer that has good adhesive strength and is less likely to cause a decrease in adhesive strength due to the influence of light or heat. Is preferable.

Further, as the acrylic polymer, in addition to the structural units described above, those having a structural unit derived from a (meth) acrylic monomer having a polar group such as a hydroxyl group, a carboxyl group or an amino group may be used. , It is preferable to obtain a conductive adhesive tape having good adhesive strength.

As the (meth) acrylic monomer having an amino group, for example, aminoethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate and the like are used. be able to.

The acrylic polymer can be produced by polymerizing a vinyl monomer containing the (meth) acrylic monomer as described above. For example, a single amount of (meth) acrylic having a carboxyl group such as acrylic acid, methacrylate, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, (anhydrous) itaconic acid, (anhydrous) maleic acid, fumaric acid, and crotonic acid. Body, (meth) acrylamide propane sulfonic acid, sulfopropyl (meth) acrylate, (meth) acryloyloxynaphthalene sulfonic acid, sodium vinyl sulfonate, styrene sulfonic acid, allyl sulfonic acid, 2- (meth) acrylamide-2-methyl propane A vinyl monomer having a sulfonic acid group such as sulfonic acid and (meth) acrylamide propane sulfonic acid, a (meth) acrylic monomer having a phosphoric acid group such as 2-hydroxyethylacryloyl phosphate and the like can be used. Among them, it is preferable to use a (meth) acrylic monomer having a carboxyl group, and it is more preferable to use acrylic acid or methacrylic acid in order to obtain a conductive adhesive tape having even better adhesive strength. ..

Examples of the vinyl monomer having a hydroxyl group that can be used in producing the acrylic polymer include 2-hydroxyethyl (meth) acrylate, 2-ethylhexyl (meth) acrylate 2-hydroxypropyl (meth) acrylate, and 3-hydroxy. Propyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2-hydroxyhexyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylic, 8-hydroxyoctyl (meth) acrylate A (meth) acrylic monomer having a hydroxyl group such as 10-hydroxydecyl (meth) acrylate and 12-hydroxylauryl (meth) acrylate can be used.

Further, as the acrylic polymer, it is preferable to use one having an aliphatic cyclic structure. Examples of the aliphatic cyclic structure include a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a propylcyclohexyl group, a tricyclo [5,2,1,0,2,6] decyl group, and a bicyclo [ 4,3,0] -nonyl group, tricyclo [5,3,1,1] dodecyl group, propyltricyclo [5,3,1,1] dodecyl group, norbornene group, isobornyl group, dicyclopentanyl group, Examples thereof include an adamantyl group, and among them, a cyclohexyl group, a norbornene group, an isobornyl group, and an adamantyl group are preferable in order to obtain a conductive adhesive tape having even more excellent adhesive strength.

The acrylic polymer can be produced by polymerizing a mixture of the vinyl monomers by, for example, a solution polymerization method, a massive polymerization method, a suspension polymerization method, an emulsion polymerization method, an ultraviolet irradiation method, or an electron beam irradiation method. it can.
As the acrylic polymer obtained by the above method, it is preferable to use one having a weight average molecular weight of 500,000 to 2.5 million, more preferably 700,000 to 2 million, and 900,000 to 1.8 million. It is more preferable to use one.

In the present invention, the weight average molecular weight Mw of the acrylic polymer can be measured by gel permeation chromatography (GPC). More specifically, it can be obtained by measuring with the following GPC measuring conditions by the polystyrene conversion value using "SC8020" manufactured by Tosoh Corporation as a GPC measuring device.
(GPC measurement conditions)
-Sample concentration: 0.5% by weight (tetrahydrofuran solution)
-Sample injection volume: 100 μL
-Eluent: tetrahydrofuran (THF)
・ Flow velocity: 1.0 mL / min
-Column temperature (measurement temperature): 40 ° C
-Column: "TSKgel GMHHR-H" manufactured by Tosoh Corporation
・ Detector: Differential refractometer

(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 to form a three-dimensional cross-linked structure in the obtained conductive pressure-sensitive adhesive layer, thereby improving the cohesive force. .. Examples of the formation of the crosslinked structure include known crosslinkers such as isocyanate-based crosslinkers, epoxy-based crosslinkers, chelate-based crosslinkers, and aziridine-based crosslinkers. The type of cross-linking agent is preferably selected according to the functional group of the above-mentioned monomer component.

(Additive)
In order to improve the adhesive strength of the conductive adhesive sheet, an adhesive resin may be added. The tackifier resin added to the conductive pressure-sensitive adhesive used in the present invention includes rosin-based resin, terpene-based resin, petroleum resin such as aliphatic (C5 series) and aromatic (C9 series), and styrene resin phenol-based resin. Examples thereof include xylene-based resins and methacrylic-based resins. Among them, a rosin-based resin is preferable, and a polymerized rosin-based resin is particularly preferable. The amount of the tackifier resin added is preferably 10 to 50 parts by mass with respect to 100 parts by mass (solid content) of the (meth) acrylic copolymer.

Various additives may be added to the pressure-sensitive adhesive used for the conductive pressure-sensitive adhesive sheet of the present invention, if necessary. Examples of the additive include a plasticizer, a softener, a metal deactivator, an antioxidant, a pigment, a dye, and the like, and are appropriately used as needed.

(Conductive particles)
The shape of the conductive particles used for the conductive pressure-sensitive adhesive layer of the conductive pressure-sensitive adhesive sheet of the present invention is scaly, flake-shaped, or plate-shaped, and the surface of the conductive particles having the largest area is mainly used. When used as a surface, the thickness with respect to the main surface is 0.5 to 6.0 μm, preferably 1.0 to 4.0 μm, more preferably 1.5 to 3.0 μm, and 1.8 to 2. 4 μm is more preferable.
The ratio of the average particle diameter of the main surface to the thickness of the conductive particles is 10 to 100, preferably 20 to 80, more preferably 30 to 60, and even more preferably 35 to 45. By setting the ratio, it is possible to obtain a conductive adhesive tape having excellent conductivity in the plane direction (XY direction) in addition to the conductivity in the thickness direction (Z-axis direction) of the pressure-sensitive adhesive sheet.

The conductive particles used in the conductive adhesive layer of the conductive adhesive sheet of the present invention include metal powder particles such as gold, silver, copper, nickel and aluminum, conductive resins such as carbon and graphite, resins, glass flakes and glass flakes. A material having a metal coating on the surface of a base material such as, etc. can be used. Among them, the use of conductive particles obtained by subjecting the particles to be the base material to metal plating provides both better adhesiveness and conductivity in the thickness direction (Z-axis direction) and the plane direction (XY direction) of the adhesive sheet. Preferred above.

The base material of the conductive particles preferably contains at least one selected from glass, silica, alumina, mica, and zirconia as a main component, and specifically contains 50% by mass or more as a component of the base material. Is more preferable, 65% by mass or more is more preferable, 80% by mass or more is more preferable, 90% by mass or more is more preferably contained, 95% by mass or more is more preferably contained, and 99% by mass or more is contained. It is more preferable that the above-mentioned trace amount of impurities is contained.
Further, as the metal used for metal plating applied to the conductive particles, it is preferable that at least one selected from silver, gold, platinum, palladium, nickel, copper and aluminum is the main component, and specifically, the above-mentioned metal is used. The metal is preferably contained in an amount of 70% by mass or more, more preferably 80% by mass or more, more preferably 90% by mass or more, and more preferably 95% by mass or more in the metal plating. It is more preferable that a trace amount of impurities of 99% by mass or more is contained.
The content of the metal plating in the conductive particles is preferably 5 to 90% by mass, more preferably 10 to 50% by mass, still more preferably 15 to 30% by mass.

The average particle diameter of the main surface of the conductive particles used in the conductive pressure-sensitive adhesive sheet of the present invention is not particularly limited, but is preferably 10 to 200 μm, more preferably 20 to 100 μm, and further preferably 40 to 40 to 200 μm. It is 90 μm. By setting the average particle diameter of the main surface of the conductive particles in the above range, it is possible to achieve both better adhesiveness and conductivity in the thickness direction (Z-axis direction) and the plane direction (XY direction) of the adhesive sheet.
The average particle size refers to a 50% cumulative value in the particle size distribution, and is a value measured by a laser analysis / scattering method. Examples of the measuring device include a Microtrack MT3000II manufactured by Nikkiso Co., Ltd., a laser diffraction type particle size distribution measuring device SALD-3000 manufactured by Shimadzu Co., Ltd., and the like.
Examples of the method for adjusting the average particle diameter in the above range include a method of pulverizing conductive particles with a jet mill and a method of sieving with a sieve or the like.

The content of the conductive particles in the conductive pressure-sensitive adhesive layer is not particularly limited, but is preferably 25 to 300 parts by mass, more preferably 40 parts by mass, based on 100 parts by mass (solid content) of the pressure-sensitive adhesive. It is ~ 200 parts by mass, more preferably 60 to 150 parts by mass, and particularly preferably 70 to 100 parts by mass. By setting the content of the conductive particles within the above range, it becomes easy to achieve both conductivity, adhesiveness, and productivity.

Examples of the method of dispersing the conductive particles in the pressure-sensitive adhesive include a method of dispersing a (meth) acrylic copolymer, a solvent, conductive particles, additives and the like with a dispersion stirrer. Examples of commercially available dispersion stirrers include dissolvers manufactured by Inoue Seisakusho, butterfly mixers, BDM twin-screw mixers, and planetary mixers. Among them, a dissolver and a butterfly mixer that can apply a medium share with less thickening of the adhesive during stirring are preferable.

The solid content of the pressure-sensitive adhesive is not particularly limited, but is preferably 10 to 90%, more preferably 30 to 85%, and most preferably 35 to 70%.

(Peeling 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, papers such as kraft paper, glassin paper, and high-quality paper, resin films such as polyethylene, polypropylene (OPP, CPP), and polyethylene terephthalate, and laminates obtained by laminating the papers and the resin film. Conventionally known paper such as paper, which is made by sealing with clay or polyvinyl alcohol on one side or both sides of the paper, and which has been subjected to peeling treatment such as silicone resin, can be used.

In an environment where the temperature of the conductive adhesive sheet of the present invention is 23 ° C. and the relative humidity is 50% RH, the conductive adhesive sheet is crimped against SUS in one reciprocating number of crimps using a 2 kg roller, and then allowed to stand for 1 hour at 300 mm / The 180 ° peeling adhesive force in min is preferably 10 to 20 N / 20 mm with respect to SUS, respectively. Within the above range, peeling can be easily suppressed, and the conductive adhesive sheet can be peeled off in a poorly bonded product in the manufacturing process.

(Conductive adhesive sheet)
The conductive pressure-sensitive adhesive sheet of the present invention preferably has a thickness of 30 μm to 75 μm, more preferably 35 μm to 65 μm, and even more preferably 40 μm to 55 μm. By setting the sheet thickness within the above range, the adhesiveness and the conductivity in the thickness direction (Z-axis direction) are excellent, the conductivity in the plane direction (XY direction) is excellent, and the electronic device is made thinner and smaller. Can contribute to. The total thickness of the conductive pressure-sensitive adhesive sheet is the thickness of the conductive pressure-sensitive adhesive sheet itself that does not include the release liner.
The conductive pressure-sensitive adhesive sheet of the present invention may or may not have a base material, but it is preferable not to have the base material in order to obtain excellent step followability.

The present invention will be specifically described below with reference to Examples, but the present invention is not limited thereto.

[Preparation of acrylic copolymer]
<Acrylic copolymer (1)>
75.94 parts by mass of n-butyl acrylate, 5 parts by mass of 2-ethylhexyl acrylate, 15 parts by mass of cyclohexyl acrylate, 4 parts by mass of acrylic acid, 4-hydroxy in a reaction vessel equipped with a cooling tube, a stirrer, a thermometer, and a dropping funnel. 0.06 parts by mass of ethyl acrylate, 4 parts by mass of 2,2'-azobisisobutylnitrile solution (2.5% by mass of solid content) and 98 parts by mass of ethyl acetate were supplied as a polymerization initiator in the reaction vessel. Was substituted with nitrogen and then polymerized at 65 ° C. for 10 hours to obtain an acrylic polymer (1) having a weight average molecular weight of 1.6 million.

<Acrylic copolymer (2)>
An acrylic polymer (2) having a weight average molecular weight of 1.6 million was obtained in the same manner as the acrylic acid copolymer (1) except that n-butyl acrylate was 90.94 parts by mass and cyclohexyl acrylate was 0 parts by mass. ..

[Preparation of adhesive]
<Adhesive A>
5 parts by mass of polymerized rosin ester-based pressure-sensitive adhesive resin D-125 (Arakawa Chemical Industry Co., Ltd.) and 15 parts by mass of petroleum-based pressure-sensitive adhesive resin FTR6125 (manufactured by Mitsui Chemicals, Inc.) with respect to 100 parts by mass of the acrylic polymer (1) A pressure-sensitive adhesive (A) having a solid content of 40% by mass was obtained by adding ethyl acetate after mixing and stirring with the part used.

<Adhesive B>
5 parts by mass of polymerized rosin ester-based pressure-sensitive adhesive resin D-125 (Arakawa Chemical Industry Co., Ltd.) and 15 parts by mass of petroleum-based pressure-sensitive adhesive resin FTR6125 (manufactured by Mitsui Chemicals, Inc.) with respect to 100 parts by mass of the acrylic polymer (2) After mixing and stirring with the part used, a pressure-sensitive adhesive (B) having a solid content of 40% by mass was obtained by adding ethyl acetate.

(Preparation of conductive adhesive composition)
[Preparation of Conductive Adhesive Composition (1A)]
Conductive particles (main surface thickness: 2 μm, main surface average diameter: 80 μm, conductive particles) obtained by silver-plating glass flake powder with respect to 100 parts by mass (solid content 40 parts by mass) of the pressure-sensitive adhesive (A). 28 parts by mass of silver plating content (20% by mass), Vernock D-40 (manufactured by DIC Co., Ltd., trimethylolpropan adduct of tolylene diisocyanate, isocyanate group content 7% by mass, non-volatile content 40% by mass) ) 2.0 parts by mass was blended, the solid content concentration was adjusted to 40% by mass with ethyl acetate, and the mixture was mixed with a dispersion stirrer to prepare a conductive pressure-sensitive adhesive (1A).

[Preparation of Conductive Adhesive Composition (2A)]
Conductive particles (main surface thickness: 2 μm, main surface average diameter: 80 μm, conductive particles) obtained by silver-plating glass flake powder with respect to 100 parts by mass (solid content 40 parts by mass) of the pressure-sensitive adhesive (A). 32 parts by mass of silver plating content (20% by mass), Vernock D-40 (manufactured by DIC Co., Ltd., trimethylol propane adduct of tolylene diisocyanate, isocyanate group content 7% by mass, non-volatile content 40% by mass) ) 2.0 parts by mass was blended, the solid content concentration was adjusted to 40% by mass with ethyl acetate, and the mixture was mixed with a dispersion stirrer to prepare a conductive pressure-sensitive adhesive (2A).

[Preparation of Conductive Adhesive Composition (3A)]
Conductive particles (main surface thickness: 2 μm, main surface average diameter: 80 μm, conductive particles) obtained by silver-plating glass flake powder with respect to 100 parts by mass (solid content 40 parts by mass) of the pressure-sensitive adhesive (A). Silver plating content in: 20% by mass) in 36 parts by mass, Burnock D-40 (manufactured by DIC Co., Ltd., trimethylol propan adduct of tolylene diisocyanate, isocyanate group content 7% by mass, non-volatile content 40% by mass ) 2.0 parts by mass was blended, the solid content concentration was adjusted to 40% by mass with ethyl acetate, and the mixture was mixed with a dispersion stirrer to prepare a conductive pressure-sensitive adhesive (3A).

[Preparation of Conductive Adhesive Composition (4A)]
Conductive particles (main surface thickness: 2 μm, main surface average diameter: 80 μm, conductive particles) obtained by silver-plating glass flake powder with respect to 100 parts by mass (solid content 40 parts by mass) of the pressure-sensitive adhesive (A). 40 parts by mass of silver plating content (20% by mass), Vernock D-40 (manufactured by DIC Co., Ltd., trimethylol propane adduct of tolylene diisocyanate, isocyanate group content 7% by mass, non-volatile content 40% by mass) ) 2.0 parts by mass was blended, the solid content concentration was adjusted to 40% by mass with ethyl acetate, and the mixture was mixed with a dispersion stirrer to prepare a conductive pressure-sensitive adhesive (4A).

[Preparation of Conductive Adhesive Composition (5A)]
Conductive particles (main surface thickness: 2 μm, main surface average diameter: 40 μm, conductive particles) obtained by silver-plating glass flake powder with respect to 100 parts by mass (solid content 40 parts by mass) of the pressure-sensitive adhesive (A). Silver plating content in: 20% by mass) in 36 parts by mass, Barnock D-40 (manufactured by DIC Co., Ltd., trimethylol propane adduct of tolylene diisocyanate, isocyanate group content 7% by mass, non-volatile content 40% by mass) ) 2.0 parts by mass was blended, the solid content concentration was adjusted to 40% by mass with ethyl acetate, and the mixture was mixed with a dispersion stirrer to prepare a conductive pressure-sensitive adhesive (5A).

[Preparation of Conductive Adhesive Composition (6A)]
Conductive particles (main surface thickness: 2 μm, main surface average diameter: 40 μm, conductive particles) obtained by silver-plating glass flake powder with respect to 100 parts by mass (solid content 40 parts by mass) of the pressure-sensitive adhesive (A). Silver plating content in: 20% by mass) in 36 parts by mass, Barnock D-40 (manufactured by DIC Co., Ltd., trimethylol propane adduct of tolylene diisocyanate, isocyanate group content 7% by mass, non-volatile content 40% by mass) ) 2.0 parts by mass was blended, the solid content concentration was adjusted to 40% by mass with ethyl acetate, and the mixture was mixed with a dispersion stirrer to prepare a conductive pressure-sensitive adhesive (6A).

[Preparation of Conductive Adhesive Composition (7A)]
With respect to 100 parts by mass (40 parts by mass of solid content) of the pressure-sensitive adhesive (A), 40 parts by mass of nickel powder NI255T (d50: 26.0 μm) manufactured by Fukuda Metal Foil Powder Industry Co., Ltd. as beaded conductive particles, as a cross-linking agent. 20 parts by mass of Vernock NC40 (manufactured by DIC Co., Ltd., trimethylolpropan adduct of tolylene diisocyanate, isocyanate group content 7% by mass, non-volatile content 40% by mass) was blended, and the solid content concentration was 40 by ethyl acetate. It was adjusted to mass% and mixed with a dispersion stirrer to prepare a conductive pressure-sensitive adhesive (7A).

[Preparation of Conductive Adhesive Composition (8A)]
Conductive particles (main surface thickness: 2 μm, main surface average diameter: 15 μm, conductive particles) obtained by silver-plating glass flake powder with respect to 100 parts by mass (solid content 40 parts by mass) of the pressure-sensitive adhesive (A). 40 parts by mass of silver plating content (20% by mass), Vernock D-40 (manufactured by DIC Co., Ltd., trimethylol propane adduct of tolylene diisocyanate, isocyanate group content 7% by mass, non-volatile content 40% by mass) ) 2.0 parts by mass was blended, the solid content concentration was adjusted to 40% by mass with ethyl acetate, and the mixture was mixed with a dispersion stirrer to prepare a conductive pressure-sensitive adhesive (8A).

[Preparation of Conductive Adhesive Composition (9A)]
Conductive particles (main surface thickness: 2 μm, main surface average diameter: 80 μm, conductive particles) obtained by silver-plating glass flake powder with respect to 100 parts by mass (solid content 40 parts by mass) of the pressure-sensitive adhesive (A). 8 parts by mass of silver plating content (20% by mass), Vernock D-40 (manufactured by DIC Co., Ltd., trimethylol propane adduct of tolylene diisocyanate, isocyanate group content 7% by mass, non-volatile content 40% by mass ) 2.0 parts by mass was blended, the solid content concentration was adjusted to 40% by mass with ethyl acetate, and the mixture was mixed with a dispersion stirrer to prepare a conductive pressure-sensitive adhesive (9A).

[Preparation of Conductive Adhesive Composition (10A)]
Conductive particles (main surface thickness: 2 μm, main surface average diameter: 80 μm, conductive particles) obtained by silver-plating glass flake powder with respect to 100 parts by mass (solid content 40 parts by mass) of the pressure-sensitive adhesive (A). Silver plating content in: 20% by mass) by 160 parts by mass, Barnock D-40 (manufactured by DIC Co., Ltd., trimethylol propane adduct of tolylene diisocyanate, isocyanate group content 7% by mass, non-volatile content 40% by mass) ) 2.0 parts by mass was blended, the solid content concentration was adjusted to 40% by mass with ethyl acetate, and the mixture was mixed with a dispersion stirrer to prepare a conductive pressure-sensitive adhesive (10A).

[Preparation of Conductive Adhesive Composition (1B)]
Conductive particles (main surface thickness: 2 μm, main surface average diameter: 80 μm, conductive particles) obtained by silver-plating glass flake powder with respect to 100 parts by mass (solid content 40 parts by mass) of the pressure-sensitive adhesive (B). Silver plating content in: 20% by mass) in 36 parts by mass, Barnock D-40 (manufactured by DIC Co., Ltd., trimethylol propane adduct of tolylene diisocyanate, isocyanate group content 7% by mass, non-volatile content 40% by mass) ) 2.0 parts by mass was blended, the solid content concentration was adjusted to 40% by mass with ethyl acetate, and the mixture was mixed with a dispersion stirrer to prepare a conductive pressure-sensitive adhesive (1B).

(Example 1)
The conductive pressure-sensitive adhesive composition (1A) is coated on a release film "PET 38 x 1 A3" manufactured by Nipper Co., Ltd. with a comma coater so that the thickness after drying is 50 μm, and is placed in a dryer at 80 ° C. for 2 minutes. It was dried. After being attached to a release film "PET 25 × 1 A3" manufactured by Nippers, it was cured at 40 ° C. for 48 hours to prepare a conductive adhesive sheet of Example 1.

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

(Example 3)
The 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 (3A) was used instead of the conductive pressure-sensitive adhesive composition (1A).

(Example 4)
The 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 (4A) was used instead of the conductive pressure-sensitive adhesive composition (1A).

(Example 5)
The conductive adhesiveness of Example 5 was the same as that of Example 1 except that the conductive adhesive composition (5A) was used instead of the conductive adhesive composition (1A) and the thickness after drying was 30 μm. I created a sheet.

(Example 6)
The conductive pressure-sensitive adhesive composition (6A) is coated on a release film "PET 38 x 1 A3" manufactured by Nippers with a comma coater so that the thickness after drying is 22 μm, and is placed in a dryer at 80 ° C. for 2 minutes. It was dried. After bonding to both sides of a copper foil having a thickness of 6 μm, it was cured at 40 ° C. for 48 hours to prepare a conductive adhesive sheet of Example 6.

(Example 7)
The 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 (1B) was used instead of the conductive pressure-sensitive adhesive composition (1A).

(Comparative Example 1)
Using the conductive pressure-sensitive adhesive composition (3A), the conductive pressure-sensitive adhesive sheet of Comparative Example 1 was prepared in the same manner as in Example 1 except that the thickness after drying was 20 μm.

(Comparative Example 2)
A conductive pressure-sensitive adhesive sheet of Comparative Example 2 was prepared in the same manner as in Example 1 except that the conductive pressure-sensitive adhesive composition (7A) was used.

(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 (8A) was used.

(Comparative Example 4)
A conductive pressure-sensitive adhesive sheet of Comparative Example 4 was prepared in the same manner as in Example 1 except that the conductive pressure-sensitive adhesive composition (9A) was used.

(Comparative Example 5)
A conductive pressure-sensitive adhesive sheet of Comparative Example 5 was prepared in the same manner as in Example 1 except that the conductive pressure-sensitive adhesive composition (10A) was used.

(Evaluation method of adhesive strength of adhesive sheet)
The adhesive strength of the adhesive sheet was determined by the following procedure according to the test method of 180 degree peeling adhesive strength of JIS-Z0237 (2000).
The conductive pressure-sensitive adhesive sheets obtained in Examples and Comparative Examples were cut into a size of 20 mm in width.
Next, the pressure-sensitive adhesive layer on one side of the conductive pressure-sensitive adhesive sheet was lined with a polyester film having a thickness of 25 μm.
Next, under the conditions of an environmental temperature of 23 ° C. and a humidity of 50%, the backed conductive adhesive sheet was attached to a stainless steel plate (SUS plate), and the upper surface was reciprocated once with a 2 kg roller to crimp them. Then, a test piece left at the above temperature for 1 hour was used as a test piece.
The test piece, Tensilon universal tensile tester (Orientec Ltd., RTA100) used, the same temperature and humidity conditions, in by peeling at a speed of 300 mm / min, a 180 degree peel adhesion _{S 20} It was measured. When the adhesive strength was 8 N / 20 mm or more, it was evaluated as having excellent conductivity.

[Evaluation method of conductivity in the Z-axis direction (measurement of resistance value 1)]
A brass electrode having a length of 30 mm and a width of 30 mm was attached to a surface made of one of the pressure-sensitive adhesive layers of a conductive pressure-sensitive adhesive sheet having a width of 30 mm and a width of 30 mm.
A copper foil (thickness 35 μm) having a length of 25 mm and a width of 25 mm was attached to the other surface of the conductive pressure-sensitive adhesive sheet.
In an environment of 23 ° C. and 50% RH, the terminals are connected to the brass electrode and the copper foil with a load of surface pressure of 20 N applied from the upper surface of the brass electrode, and a milliohm meter (NF Circuit Design Co., Ltd.) A current of 10 μA was passed through a block), and the resistance value was measured. When the resistance value was 0.1Ω or less, it was evaluated as having excellent conductivity.

[Evaluation method of XY planar conductivity (measurement of resistance value 2)]
The conductive adhesive sheet was cut into a size of 25 mm width × 100 mm width.
One of the adhesive layers of the cut conductive adhesive sheet was attached to two stainless steel plates (SUS plates) so that the attachment area was 25 mm × 25 mm (625 mm ² ). In an environment of 23 ° C. and 50% RH, connect the terminal at a position about 100 mm away from the position where the conductive adhesive sheet is attached on the SUS surface, and use a Loesta-GP MCP-T600 (manufactured by Mitsubishi Chemical Corporation) to generate a current of 10 μA. Was flown and the resistance value was measured. When the resistance value was 20Ω or less, it was evaluated as having excellent conductivity.

[Evaluation method of step followability]
The conductive adhesive sheet or the like obtained in Examples and Comparative Examples was cut into 5 cm × 5 cm, and the release film was peeled off. The release film having a thickness of 50 μm (hereinafter referred to as “# 50 release film”) was centered at 7 cm × 7 cm. It was pasted on the part.
A panel having a decorative layer (black) having a thickness of 20 μm and a width of 4 mm was prepared in a frame portion of a glass plate having a length of 4 cm and a width of 5 cm.
The # 50 release film on the pressure-sensitive adhesive layer side was removed, and the surface of the panel (the side having the decorative layer) was attached to the surface of the pressure-sensitive adhesive layer.

Next, the # 50 release film on the adhesive layer side constituting the adhesive sheet was removed, and a polyethylene terephthalate film having a length of 4 cm, a width of 5 cm and a thickness of 125 μm was attached to the surface thereof at 5 atm and 80 ° C. It was left for 20 minutes in the environment of.
The interface between the stepped portion caused by the decorative layer and the pressure-sensitive adhesive layer constituting the adhesive sheet and its surroundings were observed from the panel plate side using an optical microscope and evaluated according to the following criteria.

⊚: There was no unevenness due to distortion at the interface between the stepped portion and the conductive adhesive layer, and the appearance was excellent.
◯: Although the interface between the stepped portion and the conductive adhesive layer was slightly distorted, it had a good appearance.
Δ: The interface between the stepped portion and the conductive adhesive layer had irregularities due to strain, and a slight deterioration in appearance was confirmed.
X: The interface between the stepped portion and the conductive adhesive layer had irregularities due to strain, and it was confirmed that the appearance was deteriorated.

Claims (6)

A conductive pressure-sensitive adhesive sheet having a conductive pressure-sensitive adhesive layer.
The conductive pressure-sensitive adhesive layer contains at least one kind of conductive particles and contains.
The conductive particles are conductive particles obtained by subjecting the particles as a base material to a metal plating treatment.
The shape of the conductive particles is scaly, flake-shaped, or plate-shaped, and when the surface having the largest area in the shape of the conductive particles is the main surface, the thickness with respect to the main surface is 0.5 to 6. It is 0.0 μm, and the ratio of the average diameter of the main surface to the thickness of the conductive particles is 10 to 100.
Ri 25 to 300 parts by der against the adhesive (solid content) 100 parts by weight of the content of the conductive particles constituting the conductive adhesive layer,
In an environment with a temperature of 23 ° C and a relative humidity of 50% RH, the SUS is crimped with a 2 kg roller in one round trip, and after standing for 1 hour, 180 ° peeling adhesive force at 300 mm / min but, 10~20N / 20mm der Ru conductive adhesive sheet. The base material of the conductive particles is mainly composed of glass, silica, alumina, at least one selected from the group consisting of mica and zirconia,
The first aspect of claim 1, wherein the metal used for the metal plating applied to the conductive particles contains at least one selected from the group consisting of silver, gold, platinum, palladium, nickel, copper and aluminum as a main component. Conductive adhesive sheet. The conductive pressure-sensitive adhesive sheet according to claim 1 or 2 , wherein the average particle diameter of the main surface of the conductive particles is 10 to 200 μm. The conductive pressure-sensitive adhesive sheet according to any one of claims 1 to 3 , wherein the pressure-sensitive adhesive is an acrylic pressure-sensitive adhesive containing an acrylic polymer. The conductive pressure-sensitive adhesive sheet according to any one of claims 1 to 4, which has a release liner on the conductive pressure-sensitive adhesive layer. The conductive adhesive sheet according to any one of claims 1 to 5, which is used for shielding electromagnetic waves inside and outside electric or electronic devices and for grounding.