JP4403360B2 - Conductive adhesive sheet - Google Patents

Description

【００５３】
【表２】

【００５４】
また、銅以外の金属に対する導電性を調べるため、実施例１記載の導電性粘着テープをステンレス板（ＳＵＳ３０４）に貼付した際の抵抗値を評価したところ、４００ｍΩ/６．２５ｃｍ^２であり、本発明の導電性粘着シートはステンレスにも良好な導通が得られることを確認した。
【００５５】
【発明の効果】
以上のように、本発明によれば導電性や接着性に非常に優れる導電性粘着シートを得ることができる。本発明の導電性粘着シートは、電気、電子機器のデジタル装置、ケーブル等から輻射する不要な漏洩電磁波のシールド用、他の電気、電子機器より発生する有害な空間電磁波のシールド用、静電気帯電防止の接地固定用として有用である。
【図面の簡単な説明】
【図１】 ウニ状のニッケルパウダの写真である。
【図２】 フィラメント状のニッケルパウダの写真である。
【図３】 導電性粘着シートの構造の一例を示す断面図である。
【図４】 導電性粘着シートの構造の一例を示す断面図である。
【図５】 導電性粘着シートの構造の一例を示す断面図である。
【図６】 導電性粘着シートの構造の一例を示す断面図である。
【図７】 導電性粘着シートの構造の一例を示す断面図である。
【図８】 導電性粘着シートの構造の一例を示す断面図である。
【符号の説明】
１ 導電性基材
２ 粘着層
３ 剥離シート[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a conductive pressure-sensitive adhesive sheet using a particle-dispersed conductive pressure-sensitive adhesive, and more specifically, for shielding unwanted leakage electromagnetic waves radiated from digital devices, cables, etc. of electric and electronic devices, and the like. The present invention relates to a conductive pressure-sensitive adhesive sheet used for shielding harmful spatial electromagnetic waves generated from electricity and electronic equipment, and for grounding for preventing electrostatic charge.
[Prior art]
[0002]
Because of the ease of handling, the conductive adhesive sheet is used to shield unwanted leaked electromagnetic waves radiated from digital devices, cables, etc. of electricity and electronic equipment, and shield harmful electromagnetic waves generated from other electrical and electronic equipment, Used for grounding to prevent static electricity.
[0003]
As the conductive adhesive sheet for the above use, a particle-dispersed conductive adhesive in which conductive particles such as metal particles are dispersed in an adhesive resin, and conductivity obtained by combining it with a conductive substrate such as metal foil Adhesive sheets are known. As the conductive particles, powder made of copper, silver, nickel, aluminum, carbon, or the like is used. As the adhesive resin, acrylic resin, rubber, silicon resin, or the like is used.
[0004]
To obtain conductivity in the sheet thickness direction in a conductive adhesive sheet using a particle-dispersed conductive adhesive, the conductive particles are exposed from the surface of the adhesive layer and are in contact with the conductive substrate. Is known to be necessary (see, for example, Patent Document 1 and Patent Document 2). In these prior arts, it is described that a conductive pressure-sensitive adhesive sheet excellent in both conductivity and adhesiveness can be obtained when the particle diameter of the conductive particles is equal to or equal to or more than twice the thickness of the pressure-sensitive adhesive. . However, there is a trade-off relationship between the conductivity and the adhesive strength of the pressure-sensitive adhesive sheet, and the adhesiveness tends to decrease when the conductive particles are exposed on the surface of the pressure-sensitive adhesive layer. The pressure-sensitive adhesive sheet was inferior in adhesiveness even though the electrical conductivity was excellent.
[0005]
In particular, since the conductive particles have a particle size distribution, if a large amount of conductive particles having a particle size equal to or greater than the thickness of the pressure-sensitive adhesive is added, the conductive particles having an excessively large particle size that adversely affects the adhesiveness. Since the ratio also increases, the decrease in adhesive strength becomes significant. In order to prevent this, Patent Document 2 describes that the conductive particles are screened and the conductive particles having a specific particle size range are selected, but using such a process increases the number of manufacturing steps. In addition, conductive particles that are out of the intended particle size range are discarded, which is disadvantageous in terms of manufacturing cost.
[0006]
By the way, an example in which a polyalkyl silicone pressure-sensitive adhesive is used as the pressure-sensitive adhesive of the conductive pressure-sensitive adhesive sheet and nickel powder is used as the conductive particles has also been reported (see, for example, Patent Document 3). However, even in this technique, a conductive pressure-sensitive adhesive sheet having both excellent conductivity and adhesiveness is not disclosed.
[0007]
[Patent Document 1]
Japanese Patent Publication No.46-15240 [Patent Document 2]
Japanese Patent Laid-Open No. 5-222346 [Patent Document 3]
JP 2001-146578 A (Example 3)
[0008]
[Problems to be solved by the invention]
An object of the present invention is to provide a particle-dispersed conductive pressure-sensitive adhesive sheet that is excellent in conductivity and adhesiveness in order to solve the above-described drawbacks of the prior art.
[Means for Solving the Invention]
[0009]
As a result of intensive studies, the present inventors have found that when two or more kinds of conductive particles having a specific particle diameter are used, a particle-dispersed conductive pressure-sensitive adhesive sheet excellent in conductivity and adhesiveness can be obtained. The present invention has been completed.
[0010]
That is, the present invention is a conductive pressure-sensitive adhesive sheet provided with a pressure-sensitive adhesive layer made of a conductive pressure-sensitive adhesive in which nickel powder produced by a carbonyl method is dispersed in a pressure-sensitive adhesive material, the nickel powder being ,
(1) Particles (A) having a 50% volume particle diameter of 50% to 80% of the thickness of the adhesive layer and (2) Particles having a 50% volume particle diameter of less than 50% of the thickness of the adhesive layer (B ), And the mass ratio (A) :( B) of the particles (A) to the particles (B) is 40:60 to 80:20, and exceeds 50 parts by mass with respect to 100 parts by mass of the adhesive substance. It provides a conductive pressure-sensitive adhesive sheet containing 100 parts by mass or less.
[0011]
Since the particles (A) used in the present invention have a 50% volume particle diameter of 50% to 80% of the thickness of the adhesive layer, the particles (A) are exposed more than necessary from the surface of the adhesive layer, There are very few particles having an excessively large particle size that significantly deteriorates the adhesiveness of the conductive pressure-sensitive adhesive sheet of the present invention. On the other hand, since an appropriate amount of particles (B) having a 50% volume particle diameter of less than 50% of the thickness of the adhesive layer is contained, a conduction path through the particles (B) is formed inside the adhesive layer. Since it adds to the conduction path formed by (A), the electroconductive adhesive sheet of this invention turns into an adhesive sheet excellent in electroconductivity.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
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.
[0013]
(Adhesive composition)
As the adhesive substance used in the conductive adhesive sheet of the present invention, known acrylic, rubber-based, and silicon-based adhesives can be used, and among them, a (meth) acrylic adhesive is used. Is preferred. In particular, as a (meth) acrylic pressure-sensitive adhesive, a (meth) acrylic copolymer containing an acrylate ester having an alkyl group having 2 to 14 carbon atoms as a monomer component is suitable for weather resistance and heat resistance. To preferred. Examples of such monomers include acrylic copolymers such as n-butyl acrylate, isooctyl acrylate, 2-ethylhexyl acrylate, and isononyl acrylate, and methacrylic copolymers such as 2-ethylhexyl methacrylate. .
[0014]
Furthermore, as a monomer component, (meth) acrylic acid ester having a polar group such as a hydroxyl group, a carboxyl group, or an amino group in the side chain and other vinyl monomers are added in a range of 0.01 to 15% by mass. Is preferred. Preferably, it is preferable in terms of adjustment of the gel fraction to appropriately define a monomer component having a functional group that reacts with it to form a crosslinking point in accordance with a crosslinking agent described later. In the case of an isocyanate-based crosslinking agent, it is preferable to add a monomer component having a hydroxyl group in the side chain in the range of 0.01 to 2.0% by mass. In the case of an epoxy-based crosslinking agent or a chelate-based crosslinking agent, it is preferable to add a monomer component containing a carboxyl group in the range of 0.1 to 12% by mass.
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.
[0015]
(Gel fraction of adhesive)
The (meth) acrylic pressure-sensitive adhesive used for the conductive pressure-sensitive adhesive sheet of the present invention preferably forms a three-dimensional cross-linked structure in order to improve cohesion. As an index for forming a crosslinked structure, a gel fraction represented by an insoluble matter after being immersed in toluene, which is a good solvent for a (meth) acrylic adhesive, for 24 hours is used. In that case, it is preferable that it is 25-60 mass%, More preferably, it is 30-40 mass%. When the gel fraction is less than 25% by mass, the cohesive force in the shearing direction is insufficient, and when it exceeds 60% by mass, the peel resistance decreases.
[0016]
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
* Adhesive mass = (Mass of conductive adhesive sheet)-(Mass of substrate)-(Mass of conductive particles)
[0017]
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 not particularly defined as long as the gel fraction can be adjusted to 25 to 60% by mass.
[0018]
(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 particle-dispersed conductive adhesive used in the present invention are rosin resins, terpene resins, aliphatic (C5) and aromatic (C9) petroleum resins, and styrene resins. Examples thereof include phenolic resins, xylene resins, and methacrylic resins. As addition amount of tackifying resin, it is preferable to add 10-50 mass% with respect to 100 mass parts of (meth) acrylic-type copolymers.
[0019]
Various additives may be added to the pressure-sensitive adhesive used in the conductive pressure-sensitive adhesive tape 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.
[0020]
(Conductive particles)
The conductive particles used in the conductive pressure-sensitive adhesive sheet of the present invention are nickel powder produced by a carbonyl method, particles (A) having a 50% volume particle diameter of 50% to 80% of the thickness of the pressure-sensitive adhesive layer, and the pressure-sensitive adhesive layer. Particles (B) having a thickness of less than 50% are used in combination. Thus, by blending a specific nickel powder having a specific 50% volume particle diameter to adjust the particle size distribution of the conductive particles (for example, a particle size distribution having two or more peaks), High conductivity equivalent to that of conductive particles having a conventional single distribution can be realized, and sufficient adhesiveness that cannot be obtained by the conventional technology can be obtained. When the 50% volume particle diameter of the particles (A) exceeds 80% of the thickness of the pressure-sensitive adhesive layer, the adhesiveness is lowered.
[0021]
The apparent density of the particles (A) having a 50% volume particle diameter of 50% to 80% of the thickness of the adhesive layer is 1.5 g / cm ³ or less, preferably 1.0 g / cm ³ or less, more preferably 0.4. ~ 0.8 g / cm ³ . If the amount exceeds 1.5 g / cm ³ , the mass per particle is large, and the dispersion speed of the conductive particles when dispersed in the adhesive solution is high. It becomes difficult to get. Moreover, since it is not bulky, since it is necessary to add electroconductive particle excessively, it is not preferable.
[0022]
The particle size distribution of the particles (A) having a 50% volume particle diameter of 50% to 80% of the thickness of the adhesive layer is preferably a ratio of 95% volume particle diameter to 5% volume particle diameter (95% volume particle diameter / The numerical value of (5% volume particle diameter) is 10 to 30, more preferably 15 to 25. If it is less than 10, the conductivity decreases. On the other hand, if it exceeds 30, the adhesiveness is lowered. Examples of such nickel powder include, but are not limited to, nickel powders # 210, # 255, and # 287 manufactured by Inco Corporation.
[0023]
On the other hand, the apparent density of the particles diameter of 50% volume particle is less than 50% of the thickness of the adhesive layer (B) is 3.0 g / cm ³ or less, preferably 1.6~2.6g / cm ^3. If it exceeds 3.0 g / cm ³ , the mass per particle is large, and the dispersion speed of the conductive particles increases when dispersed in the pressure-sensitive adhesive solution. It becomes difficult to obtain a solution.
[0024]
The particle size distribution of the particles (B) having a 50% volume particle diameter of less than 50% of the thickness of the adhesive layer is preferably a ratio of 95% volume particle diameter to 5% volume particle diameter (95% volume particle diameter / 5% The numerical value of (volume particle diameter) is 15 or less, more preferably 5-12. If it exceeds 15, the effect of the addition is reduced, which is not preferable.
[0025]
Examples of such nickel powder include, but are not limited to, nickel powders # 123 and # 110 manufactured by Inco Corporation.
[0026]
The nickel powder produced by the carbonyl method is a method for producing nickel powder from nickel carbonyl by the following reaction.
Ni (CO) ₄ → Ni + 4CO
Nickel powders have various shapes, but have a dendritic (dendritic) surface shape, a sea urchin shape (FIG. 1), or a filament shape (FIG. 2). Those are preferred. Examples of the shape shown in FIG. 1 include Inco nickel powder # 123, and examples of the shape shown in FIG. 2 include # 255 and # 287.
[0027]
(Apparent density)
The apparent density of the conductive particles was measured according to JISZ2504-2000 “Measuring Method of Apparent Density of Metal Powder”.
[0028]
(Volume particle size)
The volume particle diameter of the conductive particles is a value measured with a laser diffraction particle size distribution analyzer SALD-3000 manufactured by Shimadzu Corporation using isopropanol as a dispersion medium.
[0029]
(Amount of conductive particles added)
The addition amount of the conductive particles is preferably more than 50 parts by mass and 100 parts by mass or less, more preferably 60 to 85 parts by mass with respect to 100 parts by mass of the adhesive substance. In the case of 50 parts by mass or less, the conductivity is lowered. When it exceeds 100 parts by mass, the adhesiveness is lowered. Moreover, particle | grains (A) and particle | grains (B) are used in the range from which mass ratio (A) :( B) will be 40: 60-80: 20. More preferably, it is 50: 50-70: 30. When the particle (A) is less than 40% by mass, the conductivity is lowered. When it exceeds 80 mass%, adhesiveness falls. It becomes possible to make high electroconductivity and adhesiveness compatible by mix | blending in such a ratio. Furthermore, there is an effect that the influence on the physical properties due to the correspondence of the adhesive layer of the conductive adhesive sheet to the set width and the fluctuation of the coating thickness is reduced.
[0030]
(Thickness of conductive adhesive layer)
Although the thickness of the adhesion layer of a conductive adhesive sheet is suitably set according to the 50% volume particle diameter of electroconductive particle, it is preferable that it is 10-100 micrometers, More preferably, it is 15-75 micrometers. Especially, it is especially preferable that it is 25-45 micrometers. If it is the said range, since it is excellent in the initial stage adhesiveness to a rough surface and is excellent in conduction | electrical_connection, it is preferable.
[0031]
(Peeling sheet)
In the conductive pressure-sensitive adhesive sheet of the present invention, a release sheet can be laminated on the pressure-sensitive adhesive layer. The release sheet 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.
[0032]
(Configuration of conductive adhesive sheet)
A basic configuration of the conductive pressure-sensitive adhesive sheet of the present invention is shown in FIG. FIG. 3 shows a structure in which an adhesive layer 2 made of a conductive adhesive is laminated on a conductive substrate 1. Examples of the conductive substrate 1 include metal foils such as copper foil, aluminum foil, nickel foil, and iron foil, and resins such as polyethylene terephthalate, polybutylene terephthalate, polyethylene, polypropylene, polyimide, and polyvinyl chloride on one side of the metal foil. Examples thereof include a metal foil obtained by bonding a film made of metal, a metal foil subjected to surface treatment with gold, silver, copper, nickel, tin and the like, a resin film, a conductive woven fabric, a conductive nonwoven fabric, a conductive foam, and the like. In addition, when using the electroconductive base material 1 which laminated metal foil on the nonelectroconductive resin film etc., the adhesion layer 2 is laminated | stacked on metal foil. The conductive pressure-sensitive adhesive sheet having the structure of FIG. 1 is preferably produced in a roll-shaped (rolled) embodiment. In that case, it is preferable to use what the other surface of the electroconductive base material 1 in which the adhesion layer 2 is not laminated | stacked gave the peeling process by silicon-type resin etc. FIG. Moreover, it can also be set as the form which laminated | stacked the peeling sheet 3 on the adhesion layer 2 like FIG. If it is set as such a form, it can be set as embodiment of every leaf.
[0033]
5 and 6 show a form in which the adhesive layer 2 is laminated on both surfaces of the conductive substrate 1 and the release sheet 3 is laminated on one or both of the adhesive layers 2. Thus, the electroconductive adhesive sheet of this invention can also be made into the form which laminated | stacked the adhesive layer of one or more layers in this way.
[0034]
7 and 8 show an embodiment in which the release sheet 3 is used in place of the conductive substrate 1 without using the conductive substrate 1. The conductive pressure-sensitive adhesive sheet having the structure of FIG. 7 is preferably manufactured in a roll-shaped (rolled) embodiment, similarly to the embodiment of FIG. In that case, it is preferable to use the other surface of the release sheet 3 on which the adhesive layer 2 is not laminated, which has been subjected to a release treatment with a silicon-based resin or the like. Although various cases can be considered as a method of using a conductive adhesive sheet that does not use such a conductive base material 1, for example, it is stuck between two metal plates in a state where the release sheet is peeled off, and between the metal plates. There are methods of use to ensure continuity.
[0035]
【Example】
Examples will be specifically described below, but the present invention is not limited to these examples.
[0036]
Example 1
[Preparation of acrylic pressure-sensitive adhesive composition]
In a reaction vessel equipped with a condenser, a stirrer, a thermometer, and a dropping funnel, 96.0 parts by mass of n-butyl acrylate, 0.1 part by mass of 2-hydroxyethyl acrylate, 3.9 parts by mass of acrylic acid and a polymerization initiator 0.12 parts by mass of 2,2′-azobisisobutylnitrile was dissolved in 100 parts by mass of ethyl acetate, and after nitrogen substitution, polymerization was carried out at 80 ° C. for 12 hours. For 100 parts by mass of the solid content of this adhesive 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., Superester A-100, softening point 100 ° C.) 10 parts by mass were mixed, and the resin solid content concentration was adjusted to 45% by mass with ethyl acetate to prepare an acrylic pressure-sensitive adhesive composition.
[0037]
[Preparation of particle-dispersed conductive adhesive composition]
With respect to 100 parts by mass (45 parts by mass of solid content) of the acrylic pressure-sensitive adhesive composition, # 287 (nickel powder manufactured by Incori Ltd., 50% average particle size: 19.7 μm, apparent density: 0.8 g / cm ³ ) 20.0 parts by mass, # 123 (nickel powder manufactured by Incori Ltd., 50% average particle size: 10.8 μm, apparent density: 2.4 g / cm ³ ) 10.0 parts by mass, ethyl acetate 10 parts by mass Then, 1.3 parts by mass of a crosslinking agent Coronate L (an isocyanate-based crosslinking agent manufactured by Nippon Polyurethane Industry) was added in a resin solid content ratio, and mixed for 10 minutes with a dispersion stirrer to prepare a particle-dispersed conductive adhesive.
[0038]
[Creation of conductive adhesive sheet]
This composition was coated on a release paper having a thickness of 130 μm so that the thickness of the pressure-sensitive adhesive layer after drying was 33 μm, dried in an oven at 80 ° C. for 2 minutes, and then rolled copper having a thickness of 35 μm. After pasting together with foil (BAC-13-T, Japan Energy Co., Ltd.), curing was performed at 40 ° C. for 48 hours to prepare a conductive pressure-sensitive adhesive sheet. (The 50% average particle size of # 287 is 60.0% of the pressure-sensitive adhesive layer thickness, and # 123 is 32.7%)
[0039]
(Example 2)
Conductive adhesive as in Example 1 except that # 287 was changed to 20.0 parts by mass and # 123 was changed to 20.0 parts by mass with respect to 100 parts by mass of the acrylic adhesive composition described in Example 1. Created a sheet.
[0040]
(Example 3)
A conductive adhesive sheet was prepared in the same manner as in Example 1 except that # 287 was changed to 36 parts by mass and # 123 was changed to 9 parts by mass with respect to 100 parts by mass of the acrylic adhesive composition described in Example 1. .
[0041]
Example 4
A conductive pressure-sensitive adhesive sheet was prepared in the same manner as in Example 1 except that # 287 was changed to 16 parts by mass and # 123 was changed to 22 parts by mass with respect to 100 parts by mass of the acrylic pressure-sensitive adhesive composition described in Example 1. .
[0042]
(Comparative Example 1)
A double-sided PSA sheet is obtained in the same manner as in Example 1 except that # 287 is changed to 40.0 parts by mass and # 123 is not used with respect to 100 parts by mass of the acrylic pressure-sensitive adhesive composition described in Example 1. It was.
[0043]
(Comparative Example 2)
The double-sided PSA sheet was prepared in the same manner as in Example 1 except that # 287 was not used and # 123 was changed to 40.0 parts by mass with respect to 100 parts by mass of the acrylic adhesive composition described in Example 1. Obtained.
[0044]
(Comparative Example 3)
A double-sided PSA sheet was obtained in the same manner as in Example 1 except that # 287 was changed to 20.0 parts by mass with respect to 100 parts by mass of the acrylic adhesive composition described in Example 1 and # 123 was not used. It was.
[0045]
(Comparative Example 4)
A double-sided pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that the thickness of the conductive pressure-sensitive adhesive was changed to 50 μm with respect to 100 parts by mass of the acrylic pressure-sensitive adhesive composition described in Example 1. (The 50% average particle size of # 287 is 39.4% of the pressure-sensitive adhesive layer thickness, and # 123 is 21.6%)
[0046]
(Comparative Example 5)
A double-sided pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that the thickness of the conductive pressure-sensitive adhesive was changed to 20 μm with respect to 100 parts by mass of the acrylic pressure-sensitive adhesive composition described in Example 1. (The 50% average particle size of # 287 is 98.5% of the thickness of the pressure-sensitive adhesive layer, and # 123 is 54.0%)
[0047]
(Comparative Example 6)
A double-sided PSA sheet was obtained in the same manner as in Example 1 except that # 287 was changed to 9 parts by mass and # 123 was changed to 27 parts by mass with respect to 100 parts by mass of the acrylic adhesive composition described in Example 1. .
[0048]
(Evaluation)
The conductive adhesive sheets prepared in Examples 1 to 4 and Comparative Examples 1 to 6 were measured for conductivity, adhesive strength, adhesive strength after moisture resistance deterioration, and constant load peeling, and are shown in Table 2.
[0049]
A 20 mm wide conductive adhesive sheet sample is attached to a stainless steel plate (hereinafter referred to as a stainless steel plate) that has been subjected to hairline polishing treatment with water-resistant abrasive paper having an adhesive strength of # 360, and a 2.0 kg roller and one reciprocating pressure application in an environment of 23 ° C. and 60% RH. Then, after being left at room temperature for 1 hour, the 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).
[0050]
Constant load peeling A 20 mm wide conductive adhesive sheet sample was applied to a stainless steel plate at a normal temperature and a reciprocating pressure of 2.0 kg roller and left for 1 hour at 40 ° C., and then in an environment of 23 ° C. and 60% RH. Then, a load of 200 g was applied to peel in the direction of 90 degrees, and the peel distance after 3 hours was measured.
[0051]
A test piece having a resistance value of 25 mm width × 80 mm length was affixed to a copper plate with a reciprocating pressure of 2.0 kg roller at room temperature so that the application area was 6.25 cm ² , and 1 in an environment of 23 ° C. and 60% RH. After standing for a period of time, connect the terminal to the end of the test piece and the end of the copper plate (the part that is not bonded) in the same environment, and measure the resistance when a current of 10 μA is applied using a milliohm meter (NF circuit design). did.
[0052]
[Table 1]

[0053]
[Table 2]

[0054]
Moreover, in order to investigate the electroconductivity with respect to metals other than copper, when the resistance value at the time of sticking the electroconductive adhesive tape of Example 1 to a stainless steel plate (SUS304) was evaluated, it was 400 mΩ / 6.25 cm ² , The conductive pressure-sensitive adhesive sheet of the invention was confirmed to have good conduction to stainless steel.
[0055]
【The invention's effect】
As mentioned above, according to this invention, the electroconductive adhesive sheet which is very excellent in electroconductivity and adhesiveness can be obtained. The conductive adhesive sheet of the present invention is used to shield unwanted leakage electromagnetic waves radiated from digital devices, cables, etc. of electric and electronic devices, shield harmful electromagnetic waves generated from other electric and electronic devices, and prevent electrostatic charge. It is useful for fixing the grounding.
[Brief description of the drawings]
FIG. 1 is a photograph of a sea urchin nickel powder.
FIG. 2 is a photograph of filamentary nickel powder.
FIG. 3 is a cross-sectional view showing an example of the structure of a conductive adhesive sheet.
FIG. 4 is a cross-sectional view showing an example of the structure of a conductive adhesive sheet.
FIG. 5 is a cross-sectional view showing an example of the structure of a conductive adhesive sheet.
FIG. 6 is a cross-sectional view showing an example of the structure of a conductive adhesive sheet.
FIG. 7 is a cross-sectional view showing an example of the structure of a conductive adhesive sheet.
FIG. 8 is a cross-sectional view showing an example of the structure of a conductive adhesive sheet.
[Explanation of symbols]
1 Conductive substrate 2 Adhesive layer 3 Release sheet

Claims (5)

A conductive pressure-sensitive adhesive sheet comprising a conductive base material and a pressure-sensitive adhesive layer made of a conductive pressure-sensitive adhesive in which conductive particles are dispersed in a pressure-sensitive adhesive material,
The conductive particles are:
(1) particles (A) having a 50% volume particle diameter of 50% to 80% of the thickness of the adhesive layer;
(2) Nickel powder produced by a carbonyl method using a particle (B) having a 50% volume particle diameter of less than 50% of the thickness of the adhesive layer,
The mass ratio (A) :( B) of the particles (A) to the particles (B) is 40:60 to 80:20, and the conductive particles exceed 100 parts by mass with respect to 100 parts by mass of the adhesive substance. parts by containing less,
The conductive adhesive sheet, wherein the adhesive layer has a thickness of 10 to 45 μm . The conductive adhesive sheet according to claim 1, wherein the adhesive substance is a (meth) acrylic adhesive.   The conductive adhesive sheet according to claim 1 or 2, wherein a release sheet is used instead of the conductive substrate, and an adhesive layer made of the conductive adhesive is provided on the release sheet.   The ratio of 95% volume particle diameter to 5% volume particle diameter of the particles (A) (95% volume particle diameter / 5% volume particle diameter) is 10 to 30, and the 95% volume particle diameter of the particles (B). The conductive pressure-sensitive adhesive sheet according to claim 1, wherein the ratio of the 5% volume particle diameter (95% volume particle diameter / 5% volume particle diameter) is 15 or less. 4. The apparent density of the particles (A) is 1.5 g / cm ³ or less, and the apparent density of the particles (B) is 3.0 g / cm ³ or less. 5. Conductive adhesive sheet.

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