JPH07150048A - Electrically conductive silicone rubber composition - Google Patents

Abstract

PURPOSE:To obtain an electrically condictive silicone rubber composition, excellent in storage stability and hardly changing both the curability thereof with time and the volume resistivity of an electrically conductive silicone rubber prepared by curing the composition with time. CONSTITUTION:This electrically conductive silicone rubber composition comprises (A) 100 pts.wt. organopolysiloxane having at least two alkenyl groups in one molecule, (B) an organopolysiloxane having at least two hydrogen atoms bound to silicon atom in one molecule or (B') an organopolysiloxane having at least two hydrogen atoms bound to silicon atom and at least one alkoxy group bound to the silicon atom in one molecule [the component (B) or (B') is blended in an amount so as to provide 0.5-3 hydrogen atoms bound to the silicon atom in the component (B) or (B') based on one alkenyl group in the component (A)], (C) 50-2000 pts.wt. silver powder having the surface treated with an organosilicon compound and (D) a platinum-based catalyst (in an amount sufficient to cure this composition).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive silicone rubber composition, and more specifically, it has excellent storage stability, little curability change over time, and a volume resistivity of the conductive silicone rubber obtained by curing. The present invention relates to a conductive silicone rubber composition having a small change with time.

[0002]

2. Description of the Related Art A conductive silicone rubber composition is used in a special field where heat resistance, bending resistance and conductivity are required because it cures to form a silicone rubber having excellent conductivity. Examples of such a conductive silicone rubber composition include an organopolysiloxane having at least two alkenyl groups in one molecule, an organopolysiloxane having at least two silicon-bonded hydrogen atoms in one molecule, and a platinum catalyst. A conductive silicone rubber composition composed of silver powder and silver powder (see JP-A-3-170581) has been proposed. Usually, the silver powder used to form a conductive silicone rubber is a reduced silver powder obtained by reducing an aqueous solution of silver nitrate with a reducing agent such as hydrazine, formaldehyde or ascorbic acid, and an aqueous solution of silver nitrate is electrolyzed on the cathode. Electrolytic silver powder obtained by depositing on 100
It is divided into atomized silver powders obtained by spraying molten silver heated and melted at 0 ° C or higher into water or an inert gas, and these shapes are divided into granular, flake, dendritic, and irregular shapes. In particular, flake-shaped silver powder is preferably used because it can form a highly conductive silicone rubber.

[0003]

However, Japanese Patent Laid-Open No. 3-1 is used.
In the conductive silicone rubber composition proposed in No. 70581, when flake-shaped silver powder is blended as the silver powder, if the composition is stored, the silver powder is separated into layers from the composition. There is a problem that the curability of the composition is deteriorated with time, and eventually the composition does not cure. In addition, JP-A-3-17
The conductive silicone rubber composition proposed in No. 0581 is not suitable for continuous electrical connection of conductive parts because the conductive silicone rubber obtained by curing the composition has a large change in volume resistivity with time. There was a problem.

The present inventors have a problem that the silver powder has a low affinity for the silicone rubber composition, and further, lauric acid, which was used when pulverizing the silver powder to prepare flaky silver powder, Saturated or unsaturated higher fatty acids such as myristic acid, palmitic acid, stearic acid, oleic acid, arachidic acid, behenic acid; aluminum laurate,
Metal soaps such as aluminum stearate, zinc laurate and zinc stearate; higher aliphatic alcohols such as stearyl alcohol; esters of higher aliphatic alcohols;
Higher aliphatic amines such as stearylamine; lubricants consisting of higher aliphatic amides and polyethylene waxes, or mixtures of two or more thereof, remain on the surface or inside of the silver powder, thus curing the conductive silicone rubber composition. It was confirmed that the sex decreased with time. Then, the present inventors tried to remove the lubricant remaining on the surface of the silver powder by repeatedly washing the flaky silver powder prepared with these lubricants with an organic solvent. It was confirmed that the addition of such silver powder could not sufficiently suppress the change with time of the curability of the conductive silicone rubber composition.

Further, the inventors of the present invention have found that the change in volume resistivity of the conductive silicone rubber obtained by curing the conductive silicone rubber composition containing the silver powder with time depends on the adhesiveness between the silicone rubber and the conductive portion. It was confirmed that this was due to a decrease in the particle size and a decrease in the affinity between the silicone rubber and the silver powder.

As a result of intensive studies to solve the above problems, the present inventors have found that the incorporation of a silver powder surface-treated with an organosilicon compound suppresses the change in curability over time. Further, they have found that the addition of an organic silicon compound having a silicon atom-bonded alkoxy group suppresses the change over time in the volume resistivity of the conductive silicone rubber obtained by curing, and has reached the present invention.

That is, an object of the present invention is to provide a conductive silicone rubber composition which has excellent storage stability, a small change in curability with time, and a small change in volume resistivity of a conductive silicone rubber obtained by curing with time. To provide.

[0008]

The present invention provides (A) 100 parts by weight of an organopolysiloxane having at least two alkenyl groups in one molecule, (B) at least two silicon atoms in one molecule. The amount of the organopolysiloxane having atom-bonded hydrogen atoms {(B) component is such that the amount of silicon atom-bonded hydrogen atoms of component (B) is 0.5 to 3 per 1 alkenyl group of component (A). Is. }, (C) 50 to 2000 parts by weight of silver powder surface-treated with an organosilicon compound, and (D) platinum-based catalyst {a sufficient amount to cure the present composition. } A conductive silicone rubber composition comprising: (A) 100 parts by weight of an organopolysiloxane having at least two alkenyl groups in one molecule, (B ') at least two silicon atom-bonded hydrogen atoms in one molecule. The amount of the organopolysiloxane having atoms and at least one silicon-bonded alkoxy group {(B ') component is such that one alkenyl group of the (A) component is bonded to the silicon-bonded component of the (B') component. The amount is 0.5 to 3 hydrogen atoms. }, (C) 50 to 2000 parts by weight of silver powder surface-treated with an organosilicon compound, and (D) platinum-based catalyst {a sufficient amount to cure the present composition. } The conductive silicone rubber composition comprising

First, the conductive silicone rubber composition of claim 1 will be described in detail.

The organopolysiloxane as the component (A) is the main ingredient of the present composition and has at least two alkenyl groups in one molecule. Specific examples of the alkenyl group in the component (A) include a vinyl group, an allyl group, a butenyl group, a pentenyl group, a hexenyl group and a heptenyl group, and a vinyl group is preferable. The bonding position of the alkenyl group in the component (A) is not particularly limited, and examples thereof include molecular chain terminals, molecular chain side chains, and molecular chain terminals and molecular chain side chains. Also, (A)
The silicon atom-bonded organic group other than the alkenyl group in the component is not particularly limited, and specifically, alkyl groups such as methyl group, ethyl group, propyl group, butyl group, pentyl group, and hexyl group; phenyl group, tolyl group , Aryl groups such as xylyl groups; aralkyl groups such as benzyl groups and phenethyl groups; 3-
Monovalent hydrocarbon groups such as halo-substituted alkyl groups such as chloropropyl group and 3,3,3-trifluoropropyl group are exemplified, and methyl group and phenyl group are preferable. Also,
The molecular structure of the component (A) is not particularly limited, and specific examples thereof include linear, partially branched linear, branched, and reticulated, preferably linear, partially branched linear. It is a state. Further, the viscosity of the component (A) is not particularly limited, for example,
The viscosity value at 25 ° C. is preferably in the range of 50 to 500,000 centipoise, and further 400 to 1
It is preferably in the range of 10,000 centipoise.

Specific examples of the organopolysiloxane of the component (A) include a dimethylsiloxy / methylvinylsiloxane copolymer capped with trimethylsiloxy groups at both molecular chain ends, and a methylvinylpolysiloxane with trimethylsiloxy groups capped at both molecular chain ends. , Methylvinylsiloxane / methylphenylsiloxane copolymers capped with trimethylsiloxy groups at both molecular chain ends, Dimethylsiloxane / methylvinylsiloxane / methylphenylsiloxane copolymers capped with trimethylsiloxy groups at both molecular chain ends, dimethylvinylsiloxy groups at both molecular chain ends Blocked dimethylpolysiloxane, dimethylvinylsiloxy group blocked at both ends of molecular chain Methylvinylpolysiloxane, dimethylvinylsiloxy group blocked at both ends of molecular chain Methylphenylpolysiloxane, dimethylvinylsiloxy at both ends of molecular chain Dimethylsiloxane-methylvinylsiloxane copolymer, both molecular terminals with dimethylvinylsiloxy groups dimethylsiloxane-methylphenylsiloxane copolymers, both molecular chain terminals blocked with silanol groups dimethylsiloxane-methylvinylsiloxane copolymer,
Methylvinylpolysiloxane with silanol groups blocked at both ends of the molecular chain, dimethylsiloxane / methylvinylsiloxane / methylphenylsiloxane copolymer with silanol groups blocked at both ends of the molecular chain, silicone resin consisting of R ₃ SiO _1/2 units and SiO _4/2 units , RSiO _3/2 unit silicone resin, R ₂ SiO _2/2 unit and RSiO _3/2 unit silicone resin, R ₂ SiO _2/2 unit and RSiO
Examples include silicone resins composed of _3/2 units and SiO _4/2 units, and mixtures of two or more thereof. In the unit formula of the silicone resin, R is a substituted or unsubstituted monovalent hydrocarbon group, provided that at least one R in the unit formula is an alkenyl group. Specific examples of R in the unit formula of the silicone resin include alkyl groups such as methyl group, ethyl group, propyl group, butyl group, pentyl group and octyl group; vinyl group, allyl group,
Alkenyl groups such as butenyl group, pentenyl group, hexenyl group; aryl groups such as phenyl group, tolyl group, xylyl group; aralkyl groups such as benzyl group, phenethyl group;
Examples are halo-substituted alkyl groups such as chloropropyl group and 3,3,3-trifluoropropyl group.

The organopolysiloxane as the component (B) acts as a crosslinking agent for curing the composition, and has at least two silicon-bonded hydrogen atoms in one molecule. The bonding position of the silicon atom-bonded hydrogen atom in the component (B) is not particularly limited, and examples thereof include a molecular chain terminal, a molecular chain side chain, and a molecular chain terminal and a molecular chain side chain. Further, the silicon atom-bonded organic group in the component (B) is not particularly limited, and specifically, alkyl groups such as methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group; phenyl group, tolyl group. Group, aryl group such as xylyl group; aralkyl group such as benzyl group and phenethyl group; 3-chloropropyl group, 3,
A monovalent hydrocarbon group such as a halo-substituted alkyl group such as a 3,3-trifluoropropyl group is exemplified, preferably a methyl group,
It is a phenyl group. Further, the molecular structure of the component (B) is not particularly limited, and specific examples thereof include linear, partially branched linear, branched, and net-like, and preferably linear and partially branched. It is linear. The viscosity of the component (B) is not particularly limited, and for example, the viscosity value at 25 ° C is 1 to
It is preferably in the range of 50,000 centipoise, and more preferably in the range of 5 to 1,000 centipoise.

Specific examples of the organopolysiloxane of the component (B) include methylhydrogenpolysiloxane endcapped with trimethylsiloxy groups at both molecular chain ends, and dimethylsiloxane endcapped with trimethylsiloxy groups at both molecular chain ends.
Methyl hydrogen siloxane copolymer, molecular chain both ends trimethylsiloxy group blocked methyl hydrogen siloxane / methyl phenyl siloxane copolymer, molecular chain both ends trimethyl siloxy group blocked dimethyl siloxane / methyl hydrogen siloxane / methyl phenyl siloxane copolymer , Dimethylpolysiloxane with dimethylhydrogensiloxy group blocked at both ends of the molecular chain, methylhydrogenpolysiloxane with dimethylhydrogensiloxy group blocked at both ends of the molecular chain, dimethylsiloxane / methylhydrogensiloxane copolyester with dimethylhydrogensiloxy group blocked at both ends of the molecular chain Copolymerization, dimethylhydrogensiloxy group-capped dimethylhydrogensiloxysiloxane copolymer at both ends of the molecular chain Xyl group-blocked methylphenylpolysiloxane, molecular chain both-end silanol group-blocked methylhydrogenpolysiloxane, molecular chain both-end silanol group-blocked dimethylsiloxane-methylhydrogensiloxane copolymer, molecular chain both-end silanol group-blocked methylhydrogensiloxane Examples thereof include a methylphenylsiloxane copolymer, a silanol group-capped dimethylsiloxane having both molecular chain terminals, a methylhydrogensiloxane, and a methylphenylsiloxane copolymer.

In this composition, the blending amount of the component (B) is
The amount is such that 0.5 to 3 silicon atom-bonded hydrogen atoms in the component (B) are contained per one alkenyl group in the component (A).
This is because the blending amount of the component (B) is the alkenyl group 1 of the component (A).
The number of silicon-bonded hydrogen atoms in component (B) is 0.5
If the amount is less than the number, the obtained composition will not be sufficiently cured, and if the amount is more than 3, the amount of the conductive silicone rubber obtained by curing will be This is because the heat resistance will be significantly reduced.

The component (C) silver powder is a component for imparting conductivity to the silicone rubber obtained by curing the present composition, and its surface is treated with an organosilicon compound. Specific examples of such component (C) include reduced silver powder, electrolytic silver powder, and atomized silver powder which are surface-treated with an organosilicon compound. The silver powder of the component (C) is made of pure silver or a silver alloy, and as the silver alloy, a silver-copper alloy and a silver-palladium alloy are typical, and other trace amounts of metals such as zinc, tin, magnesium and nickel are contained. Examples thereof include silver alloys, but the content of impurities adhering to silver powder, especially NH ⁴⁺ , is 10 ppm or less, and SO ₄ ²⁻
It is preferable that the content rate of is 5 ppm or less. Also, (C)
The particle size of the component is not particularly limited, but the average particle size is preferably in the range of 0.1 to 10 μm. Further, the shape of the component (C) is not particularly limited, for example, granular, dendritic, flake-shaped, indefinite shape, and may be a mixture of silver powder having these shapes, high conductivity. In order to form silicone rubber, it is preferable to use flake-shaped silver powder.

Specific examples of the organosilicon compound for treating the surface of the component (C) include methyltrimethoxysilane, vinyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, Alkoxysilanes such as dimethyldimethoxysilane, trimethylmethoxysilane, trimethylethoxysilane, tetramethoxysilane and tetraethoxysilane; silanol group-capped dimethylsiloxane oligomers at both molecular chain ends, silanol group-capped dimethylsiloxane / methylvinylsiloxane co-polymers at both molecular chain ends Combined oligomer, Methyl vinyl siloxane oligomer with silanol groups capped at both molecular chain ends, Methyl phenyl siloxane oligomer with silanol groups capped at both molecular chain ends, 1,3,5,7-tetramethyltetracyclo Rokisan, 1,3,5,7,8
-Siloxane oligomers such as pentamethylpentacyclosiloxane; dimethylpolysiloxane blocked with trimethylsiloxy groups at both molecular chain ends, dimethylsiloxane / methylvinylsiloxane copolymer with trimethylsiloxy groups blocked at both molecular chain terminals, dimethylsiloxy group blocked with trimethylsiloxy groups at both molecular chain ends・ Methylphenyl siloxane copolymer, dimethylsiloxy group-blocked methyl hydrogen polysiloxane at both molecular chain ends, dimethylsiloxy group-blocked dimethylsiloxane at both molecular chain ends, methylhydrogensiloxane copolymer, silanol group-blocked dimethylpolyene at both molecular chain ends Siloxane, dimethylsiloxane / methylvinylsiloxane copolymer capped with silanol groups at both ends of the molecular chain, dimethylsiloxane / methylphenylsiloxy block with silanol groups at both ends of the molecular chain Copolymer, Methylhydrogenpolysiloxane with silanol groups at both ends of the molecular chain, Dimethylsiloxane / methylhydrogensiloxane copolymer with silanol groups at both ends of the molecular chain, Dimethylpolysiloxane with dimethylvinylsiloxy groups at both ends of the molecular chain, Molecule Chain end dimethylvinylsiloxy group-blocked dimethylsiloxane / methylvinylsiloxane copolymer, molecular chain terminal dimethylvinylsiloxy group-blocked dimethylsiloxane / methylphenylsiloxane copolymer, molecular chain terminal dimethylhydrogensiloxy group-blocked methylhydrogen polysiloxane, diorgano polysiloxane from low viscosity, such as at both molecular terminals with dimethylhydrogensiloxy groups dimethylsiloxane-methylhydrogensiloxane copolymer to a gum; R _'3 Si _1/2 units and SiO
Silicone resin consisting of _4/2, silicone resin consisting of R'SiO _3/2 units, R _'2 SiO _2/2 units and R'S
silicone resin consisting iO _3/2 units, R _'2 SiO _2/2
A silicone resin such as a silicone resin composed of units, R′SiO _3/2 units and SiO _4/2 units is exemplified, and these organosilicon compounds may be used alone or in combination of two or more kinds. In the unit formula of the silicone resin, R'is a substituted or unsubstituted monovalent hydrocarbon group, and specifically, an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group and an octyl group. ; Vinyl group, allyl group, butenyl group, pentenyl group,
Alkenyl groups such as hexenyl group; aryl groups such as phenyl group, tolyl group, xylyl group; aralkyl groups such as benzyl group, phenethyl group; 3-chloropropyl group, 3,
Substituted alkyl groups such as 3,3-trifluoropropyl group are exemplified. When a silicone resin is used as the organosilicon compound, the silicone resin is preferably a solid one that is softened at a temperature higher than room temperature, and its preferable softening point is in the range of 50 to 150 ° C.

In the silver powder of the component (C), a coating film made of the above-mentioned organosilicon compound or a condensation polymer thereof may be formed on the surface of the silver powder. In this case, the thickness of the coating film is not particularly limited, and it may be a thin film. If so, the more preferable it is because the silicone rubber obtained by blending with the silicone rubber composition has excellent conductivity, but the affinity with the silicone rubber composition decreases, and further, this silver powder is subjected to an addition reaction. When compounded in a curable silicone rubber composition, the curability of the composition changes with time, so the thickness of the coating must be appropriately selected according to the purpose, but it is preferably 0.1 μm or less. preferable. Further, in order to obtain a silicone rubber having excellent conductivity, an excess of the above-mentioned organosilicon compound or its polycondensation product adhering to the surface of the silver powder may be washed and removed with an organic solvent.

The method for producing the component (C) is not particularly limited. For example, a reduced silver powder prepared by reducing an aqueous solution of silver nitrate with a reducing agent such as hydrazine, formaldehyde, ascorbic acid, or an aqueous solution of silver nitrate is electrolyzed. Dendritic electrolytic silver powder deposited on the cathode by decomposition, or 100
Using a silver powder such as atomized silver powder prepared by spraying molten silver heated and melted at 0 ° C. or higher into water or an inert gas, and more preferably the content of NH ⁴⁺ contained in the silver powder. Of 10 ppm or less and a SO ₄ ^2- content of 5 ppm or less is used to wet the organic silicon compound itself or an organic solvent solution of the organic silicon compound, A method of treating the surface of the powder with an organic silicon compound can be mentioned. The method of wetting the silver powder with the organosilicon compound itself or with the organic solvent solution of the organosilicon compound is not particularly limited, and for example, an organosilicon compound or an organic solvent solution of the organosilicon compound is sprayed onto the silver powder. A method, a method of immersing silver powder in an organic solvent solution of an organic silicon compound or an organic silicon compound, a method of pulverizing silver powder using an organic solvent solution of an organic silicon compound or an organic silicon compound as a lubricant, and particularly, a conductive material Since a flake-shaped silver powder for forming a silicone rubber having excellent properties can be produced, a method of pulverizing the silver powder using an organic silicon compound or an organic solvent solution of the organic silicon compound as a lubricant is preferable. In this method, the organosilicon compound is adsorbed on the surface of the flake-shaped silver powder activated along with the pulverization of the silver powder, preventing the flake-shaped silver powder from aggregating and promoting the scaling of the silver powder. Has a function, especially
It is preferable because it acts as a surface treatment agent for the silver powder and can give good results to the obtained flaky silver powder. The device for pulverizing the silver powder is not particularly limited, and examples thereof include known devices such as a stamp mill, a ball mill, a vibration mill, a hammer mill, a rolling roller and a mortar. The conditions for rolling the silver powder composed of reduced silver, atomized silver, electrolytic silver or a mixture of two or more of these are not particularly limited, and it is necessary to select the conditions depending on the particle size and shape of the silver powder used. Also, when crushing silver powder, heat is generated,
Preference is given to cooling the milling device. The silver powder thus obtained has a flake shape, and its particle size is not particularly limited, but is preferably 0.1 to 10 μm.
The range is m.

Further, when the component (C) is produced, an organic solvent solution of an organosilicon compound is used when the viscosity of the organosilicon compound is relatively high or in order to form a thin film of the organosilicon compound on the surface of the silver powder. Preference is given to using. The type of organic solvent that can be used is not particularly limited, and examples thereof include alcoholic organic solvents such as methanol, ethanol and isopropanol; aliphatic organic solvents such as hexane, heptane, octane; cycloaliphatic such as cyclohexane and cyclooctane. Group organic solvents; aromatic organic solvents such as toluene and xylene; ketone organic solvents such as acetone, methyl ethyl ketone and methyl isobutyl ketone; ester organic solvents such as ethyl acetate and carbitol acetate.

In producing the component (C), the conditions for surface-treating the silver powder with the organosilicon compound are not particularly limited, and the temperature range is from room temperature to 100 ° C., and further at a temperature of 50 ° C. or higher, 24 It is preferable to treat for about 150 hours. The silver powder surface-treated with the organosilicon compound in this way is washed at room temperature after being washed with the organic solvent in order to facilitate the drying of the silver powder and further to remove the excess organosilicon compound adhering to the surface of the silver powder. It is preferable to dry for 24 hours or more in the temperature range of to 105 ° C.

In this composition, the compounding amount of the component (C) is
It is in the range of 50 to 2000 parts by weight, preferably in the range of 300 to 600 parts by weight, relative to 100 parts by weight of component (A). This is because if the amount of the component (C) blended is less than 50 parts by weight relative to 100 parts by weight of the component (A), the conductivity of the obtained silicone rubber will be significantly reduced.
This is because if it exceeds 000 parts by weight, the fluidity of the obtained composition remarkably decreases, and the handling work of the composition becomes extremely difficult.

The platinum catalyst as the component (D) is a catalyst for accelerating the curing of the present composition, and generally known compounds can be used as catalysts for hydrosilylation reaction. like this
Specific examples of the component (C) include platinum black, platinum-supported alumina powder, platinum-supported silica powder, platinum-supported carbon powder, chloroplatinic acid, alcohol solution of chloroplatinic acid, chloroplatinic acid-olefin complex. , A complex of chloroplatinic acid and vinyl siloxane, and a platinum-based platinum-based catalyst obtained by dispersing the platinum-based catalyst of these examples in a thermoplastic organic resin such as methyl methacrylate resin, polycarbonate resin, polystyrene resin, or silicone resin. A catalyst is illustrated.

In the present composition, the blending amount of the component (D) is not particularly limited as long as it is an amount sufficient to cure the composition of the present invention, and for example, the total of the component (A) and the component (B). The amount is preferably 1 to 100 ppm as platinum metal in the component (D) with respect to the amount.

The present composition is obtained by uniformly blending the above-mentioned components (A) to (D), but in order to suppress the contact resistance and volume resistivity of the obtained conductive silicone rubber from changing with time. As an optional component of (E), it is preferable to add the organosilicon compound having a silicon atom-bonded alkoxy group as the component (E). Specific examples of the organosilicon compound as the component (E) include tetramethoxysilane, tetraethoxysilane,
Dimethyldimethoxysilane, methylphenyldimethoxysilane, methylphenyldiethoxysilane, phenyltrimethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, vinyltrimethoxysilane, allyltrimethoxysilane, allyltriethoxysilane, 3
Examples thereof include alkoxysilanes such as glycidoxypropyltrimethoxysilane and 3-methacryloxypropyltrimethoxysilane. Since a conductive silicone rubber composition having excellent adhesiveness can be prepared, it is represented by the following formula. Organosilicon compounds are exemplified.

[0025]

[Chemical 1]

[Chemical 2]

[Chemical 3]

[Chemical 4]

[Chemical 5] (In the formula, a is an integer of 1 or more, and b is an integer of 1 or more.)

In this composition, the component (E) may be blended in an arbitrary amount, preferably 20 parts per 100 parts by weight of the component (A).
It is less than or equal to parts by weight, more preferably 0.5 to 8 parts by weight. This is because when the component (E) is not added, the resulting silicone rubber does not have adhesiveness, and there is a possibility that the contact resistance and volume resistivity of this silicone rubber may change over time. And also
When the compounding amount of the component (E) exceeds 20 parts by weight with respect to 100 parts by weight of the component (A), the storage stability of the obtained composition decreases, and the hardness of the obtained silicone rubber changes with time. Because it will be higher.

In this composition, 3-methyl-1-butyn-3-ol, 3 and 3-methyl-1-butyn-3-ol are used as optional components for improving the storage stability of the conductive silicone rubber composition and the handling workability thereof. , 5-dimethyl-1-hexyne-
Alkyne alcohols such as 3-ol and phenylbutynol; enyne compounds such as 3-methyl-3-pentene-1-yne and 3,5-dimethyl-3-hexene-1-yne;
1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane, 1,3,5,7-tetramethyl-1,3,5,7-tetrahexenylcyclototrasiloxane, A curing inhibitor such as benzotriazole can be added. The compounding amount of these curing inhibitors is preferably 0.001 to 5 parts by weight with respect to 100 parts by weight of the component (A). Further, the conductive silicone rubber composition of the present invention may contain an inorganic filler as an optional component for imparting appropriate hardness and strength to the conductive silicone rubber obtained by curing. Examples of the inorganic filler that can be added to the present composition include fumed silica, crystalline silica, pyrogenic silica, wet silica, fumed titanium oxide, carbon black, and inorganic fillers such as organoalkoxysilane, organochlorosilane, and organochlorosilane. An inorganic filler surface-treated with an organosilicon compound such as disilazane can be used. The blending amount of these inorganic fillers is preferably 50 parts by weight or less with respect to 100 parts by weight of the component (A).

Next, the conductive silicone rubber composition of claim 2 will be described.

The organopolysiloxane as the component (A) is the main agent of the present invention and is required to have at least two alkenyl groups in one molecule. Examples of the component (A) include the same organopolysiloxanes as described above.

The organopolysiloxane as the component (B ') acts as a cross-linking agent and an adhesion-imparting agent for curing the composition, and contains at least two silicon atom-bonded hydrogen atoms and at least one hydrogen atom in one molecule. It is necessary to have a silicon atom-bonded alkoxy group. The bonding position of the silicon atom-bonded hydrogen atom in the component (B ') is not particularly limited, and examples thereof include a molecular chain end, a molecular chain side chain, a molecular chain end and a molecular chain side chain, and the (B') component. The bonding position of the silicon atom-bonded alkoxy group therein is not particularly limited, and examples thereof include a molecular chain terminal, a molecular chain side chain, and a molecular chain terminal and a molecular chain side chain. Further, as the organic group other than the silicon atom-bonded alkoxy group in the component (B '), specifically, a methyl group, an ethyl group,
Alkyl groups such as propyl group, butyl group, pentyl group and hexyl group; aryl groups such as phenyl group, tolyl group and xylyl group; aralkyl groups such as benzyl group and phenethyl group;
Examples thereof include halo-substituted alkyl groups such as a 3-chloropropyl group and a 3,3,3-trifluoropropyl group, and a methyl group and a phenyl group are preferable. Further, the molecular structure of the component (B ') is not particularly limited, and specific examples thereof include linear, partially branched linear, branched, cyclic, and reticulated, and organopoly having these structures. It may be a mixture of two or more siloxanes. Further, the viscosity of the component (B ') is not particularly limited, and for example, the value of the viscosity at 25 ° C is 1 to 50,0.
It is preferably in the range of 00 centipoise, and more preferably in the range of 5 to 1,000 centipoise.

Specific examples of the organopolysiloxane as the component (B ') include organopolysiloxanes represented by the following formula.

[Chemical 6]

[Chemical 7]

[Chemical 8]

[Chemical 9] (In the formula, a is an integer of 1 or more, and c is an integer of 2 or more.)

The method for preparing the organopolysiloxane as the component (B ') is not particularly limited, and for example, an organopolysiloxane having at least three silicon-bonded hydrogen atoms in one molecule in the presence of a platinum catalyst. Method for partial addition reaction of alkenyl group-containing alkoxysilane to siloxane, alkenyltrialkoxysilane and alkenyl group-containing epoxy compound to organopolysiloxane having at least 4 silicon atom-bonded hydrogen atoms in one molecule in the presence of platinum catalyst The method of partial addition reaction is mentioned. Specific examples of the platinum-based catalyst include the same catalysts as the component (D). Organopolysiloxanes having at least three silicon-bonded hydrogen atoms in one molecule include methylhydrogenpolysiloxane blocked with trimethylsiloxy groups at both ends of the molecular chain, and dimethylsiloxane methylhydrogen blocked with trimethylsiloxy groups at both ends of the molecular chain. Siloxane copolymer, dimethylhydrogensiloxy group-blocked methylhydrogenpolysiloxane at both molecular chain ends, dimethylhydrogensiloxy group-blocked dimethylsiloxane / methylhydrogensiloxane copolymer at both molecular chain ends, cyclic methylhydrogensiloxane, cyclic dimethyl An example is a siloxane / methyl hydrogen siloxane copolymer. Moreover, as the organopolysiloxane having at least four silicon-bonded hydrogen atoms in one molecule, the same organopolysiloxane as described above is exemplified. Further, as the alkenyl group-containing alkoxysilane, specifically, vinyltrimethoxysilane,
Examples are vinyltriethoxysilane, vinylmethyldimethoxysilane, vinyldimethylmethoxysilane, allyltrimethoxysilane, allyltriethoxysilane, allylmethyldimethoxysilane, allyldimethylmethoxysilane and butenyltrimethoxysilane. Examples of the alkenyl group-containing epoxy compound include vinyl glycidyl ether, allyl glycidyl ether, butenyl glycidyl ether, 3,4-epoxycyclohexyl ethene,
3- (3,4-epoxycyclohexyl) propene, 4
An example is-(3,4-epoxycyclohexyl) butene. In the method for preparing the component (B '), the blending amount of the alkenyl group-containing alkoxysilane and the alkenyl group-containing epoxy compound is such that the alkenyl group-containing alkoxysilane and the silicon atom-bonded hydrogen atom of the organopolysiloxane as the raw material are It is necessary to react the alkenyl groups of the alkenyl group-containing epoxy compound in a short equivalent amount.

In this composition, the blending amount of the component (B ') is
It is necessary that the amount is 0.5 to 3 silicon-bonded hydrogen atoms in the component (B ') with respect to one alkenyl group in the component (A). This is because the blending amount of component (B ') is (A)
This is because if the amount of the silicon atom-bonded hydrogen atoms in the component (B ′) is less than 0.5 per component alkenyl group, the resulting composition will not be sufficiently cured. ,
This is because if the amount is more than 3, the heat resistance of the conductive silicone rubber obtained by curing will be significantly reduced.

The component (C) silver powder is a component for imparting conductivity to the silicone rubber obtained by curing the present composition, and its surface is treated with an organosilicon compound. Specific examples of the component (C) include silver powders similar to the above. Moreover, as a method for preparing such a silver powder of the component (C), the same method as described above is exemplified.

In this composition, the compounding amount of the component (C) is
It is necessary to be in the range of 50 to 2000 parts by weight, preferably 300 to 600 parts by weight, relative to 100 parts by weight of the component (A). This is because when the compounding amount of the component (C) is less than 50 parts by weight relative to 100 parts by weight of the component (A), the conductivity of the obtained silicone rubber is remarkably reduced, and this is 2000 parts by weight. This is because if it exceeds the range, the fluidity of the obtained composition is remarkably reduced, and the handling workability of the composition becomes extremely difficult.

The platinum catalyst as the component (D) is a catalyst for promoting the curing of the present composition, and the same catalysts as mentioned above are exemplified. Further, in the present composition, the amount of the component (D) is not particularly limited, as long as it is an amount sufficient to cure the composition of the present invention, for example, (A) component and (B ') component The amount is preferably 1 to 100 ppm as platinum metal in the component (D) with respect to the total amount.

The present composition can be obtained by uniformly blending the above-mentioned components (A) to (D), and as an optional component for further improving the adhesiveness of the obtained conductive silicone rubber, It is preferable to incorporate an organosilicon compound of component E ′) which has no or one silicon atom-bonded hydrogen atom in one molecule and has a silicon atom-bonded alkoxy group. Specific examples of the organosilicon compound as the component (E ') include, among the organosilicon compounds exemplified as the component (E), an organosilicon compound having no silicon atom-bonded hydrogen atom or one silicon atom-bonded hydrogen atom. An organic silicon compound is illustrated. In this composition, the component (E ') may be blended in an arbitrary amount, and the blending amount of the component (E') is 20 parts by weight or less, preferably 0.5 to 8 parts, relative to 100 parts by weight of the component (A).
The range is parts by weight.

Further, in the present composition, the above-exemplified curing inhibitor can be blended as an optional component for improving the storage stability and the handling workability of the conductive silicone rubber composition. The amount of this curing inhibitor compounded is
The amount is preferably 0.001 to 5 parts by weight with respect to 100 parts by weight of the component (A). Further, the conductive silicone rubber composition of the present invention may contain an inorganic filler as an optional component for imparting appropriate hardness and strength to the conductive silicone rubber obtained by curing. Examples of the inorganic filler that can be added to the composition include the same inorganic fillers as described above. The blending amount of the inorganic filler is preferably 50 parts by weight or less with respect to 100 parts by weight of the component (A).

In such a conductive silicone rubber composition of the present invention, the conductive silicone rubber obtained by curing has a volume resistivity of 10 Ω · cm or less, more preferably 1
Since it is less than × 10 ⁻³ Ω · cm, it can be used as a conductive adhesive, a conductive die bonding agent, a heat radiation die bonding agent, an electromagnetic wave shielding agent, and the like.

[0040]

EXAMPLES The conductive silicone rubber composition of the present invention will be described in detail with reference to Examples. In the examples, the viscosity value is a value measured at 25 ° C. Further, various properties of the conductive silicone rubber composition were measured as follows.

Appearance of Conductive Silicone Rubber Composition After preparing the conductive silicone rubber composition, the composition was refrigerated and stored in a transparent glass bottle, and immediately after preparation (initial stage), after 1 month,
The appearance of the composition was observed after 3 months and 6 months. Curable property of conductive silicone rubber composition After preparing a conductive silicone rubber composition, store the composition in a refrigerator, and immediately after the preparation (initial), one month, three months, and six months, the composition is The hardness of the silicone rubber obtained by heating at 150 ° C. for 30 minutes was measured and evaluated by the JIS A hardness meter described in JIS K6301. Contact Resistance of Silicone Rubber A conductive silicone rubber composition was applied on a circuit board and then heated at 150 ° C. for 30 minutes to obtain a silicone rubber. The contact resistance of this silicone rubber was measured by the four-point probe method (initial). In addition, the circuit board coated with this silicone rubber is placed in an oven at 150 ° C. for 100 hours for 50 hours.
After standing for 0 hour and 1000 hours, the contact resistance of this silicone rubber was measured in the same manner as above. ○ Volume resistivity of silicone rubber The conductive silicone rubber composition was heated at 150 ° C for 30 minutes to obtain a conductive silicone rubber sheet having a thickness of 1 mm or more. The volume resistivity of the silicone rubber sheet was measured by a volume resistivity measuring device [K-705RL manufactured by Kyowa Riken Co., Ltd.] (initial). Further, in order to measure the change with time of the volume resistivity of this silicone rubber, this silicone rubber sheet was placed in an oven at 150 ° C. for 100 hours for 500 hours.
After standing for 1000 hours and 1000 hours, the volume resistivity of this silicone rubber sheet was measured in the same manner as above. ○ Adhesiveness of Silicone Rubber The adhesiveness of the conductive silicone rubber composition was measured according to the tab adhesion test method. The conductive silicone rubber composition was heated on an aluminum plate at 150 ° C. for 30 minutes to form a bead-shaped (width 20 mm × length 20 mm × thickness 5 mm) silicone rubber. The bead-shaped silicone rubber was pulled, peeled off from the aluminum plate, and the peeled surface was observed. CF when cohesive fracture occurs with silicone rubber
The case where the interface is completely peeled is designated as AF, the case where the interface is partially peeled is designated as AF, and the case where the thin silicone rubber is adhered to the aluminum plate is TC.
It was evaluated as F.

Example 1 20 g of silver nitrate was dissolved in 40 ml of water, and a 46% aqueous sodium hydroxide solution was added thereto to precipitate granular silver oxide. After reducing the granular silver oxide with formalin, washing and filtration were repeated to prepare granular reduced silver powder having an average particle size of 1 μm. Then, this reduced silver powder has a softening point of 90 ° C. and an average unit formula:

[Chemical 10] Was immersed in a carbitol acetate solution of methylphenyl silicone resin represented by. Next, the silver powder surface-treated with the above methylphenyl silicone resin was collected by a filter paper and then dried at room temperature to prepare a granular silver powder having an average particle size of 1 μm.

600 parts by weight of silver powder surface-treated with the above methylphenyl silicone resin, viscosity 2000
Centipoise molecular chain both ends dimethylvinylsiloxy group blocked dimethylpolysiloxane (vinyl group content = 0.2
100 parts by weight, viscosity of 30 centipoise, both ends of the molecular chain blocked with trimethylsiloxy groups, methylhydrogenpolysiloxane (silicon atom-bonded hydrogen atom content = 1.
5 parts by weight), 1 part by weight, 7 parts by weight of 3-glycidoxypropyltrimethoxysilane, a complex of chloroplatinic acid and vinyl siloxane (in this composition, platinum metal in the complex is 5 pp
It is the amount that becomes m. ) And phenylbutynol (the amount of which is 300 ppm in the present composition) are uniformly mixed to prepare the conductive silicone rubber composition of the present invention. The appearance of this conductive silicone rubber composition, the curability of the composition, the contact resistance and volume resistivity of the silicone rubber obtained by curing the composition, and the adhesiveness of the composition were measured. The results are shown in Table 1.

Comparative Example 1 20 g of silver nitrate was dissolved in 40 ml of water, and a 46% aqueous sodium hydroxide solution was added thereto to precipitate granular silver oxide. After reducing the granular silver oxide with formalin, washing and filtration were repeated to prepare granular silver powder having an average particle size of 1 μm.

600 parts by weight of this silver powder, 100 parts by weight of dimethylvinylsiloxy group-blocked dityl polysiloxane (vinyl group content = 0.2% by weight) at both ends of the molecular chain having a viscosity of 2000 centipoise, and both ends of a molecular chain having a viscosity of 30 centipoise 1 part by weight of trimethylsiloxy group-blocked methylhydrogenpolysiloxane (silicon atom-bonded hydrogen atom content = 1.5% by weight), 7 parts by weight of 3-glycidoxypropyltrimethoxysilane, a complex of chloroplatinic acid and vinylsiloxane (The amount of platinum metal in the complex is 5 ppm in the present composition.) And phenylbutynol (the amount of 300 ppm in the present composition) are uniformly mixed, and the conductive silicone rubber composition is obtained. Was prepared. The appearance of this conductive silicone rubber composition, the curability of the composition, the contact resistance and volume resistivity of the silicone rubber obtained by curing the composition, and the adhesiveness of the composition were measured. The results are shown in Table 2.

Example 2 20 g of silver nitrate was dissolved in 40 ml of water, and a 46% aqueous sodium hydroxide solution was added thereto to precipitate granular silver oxide. After reducing the granular silver oxide with formalin, washing,
Filtration was repeated to prepare granular reduced silver powder having an average particle size of 1 μm. Then the softening point is 90 ° C. and the average unit formula:

[Chemical 11] With a carbitol acetate solution of methylphenyl silicone resin represented by as a lubricant, this reduced silver powder is crushed in a ball mill, and then silver powder surface-treated with the methylphenyl silicone resin is washed with xylene. A flake-shaped silver powder having an average particle size of 8 μm was prepared.

400 parts by weight of this flaky silver powder, 100 parts by weight of a dimethylvinylsiloxy group-blocked dimethylvinylsiloxy group (both vinyl group content = 0.2% by weight) at both ends of a molecular chain having a viscosity of 2000 centipoise, and a molecule having a viscosity of 30 centipoise. 1 part by weight of methylhydrogenpolysiloxane with trimethylsiloxy groups blocked at both ends of the chain (content of hydrogen atoms bonded to silicon atom = 1.5% by weight), 7 parts by weight of 3-glycidoxypropyltrimethoxysilane, chloroplatinic acid and vinylsiloxane And a phenylbutynol (an amount of which is 300 ppm in the present composition) of platinum metal in the complex (the amount of platinum metal in the complex is 5 ppm of the present composition) are uniformly mixed to obtain the present invention. A conductive silicone rubber composition was prepared. The appearance of this conductive silicone rubber composition,
The curability of the composition, the contact resistance and volume resistivity of the silicone rubber obtained by curing the composition, and the adhesiveness of the composition were measured. The results are shown in Table 1.

Comparative Example 2 20 g of silver nitrate was dissolved in 40 ml of water, and a 46% aqueous sodium hydroxide solution was added to the solution to precipitate granular silver oxide. After reducing the granular silver oxide with formalin, washing,
Filtration was repeated to prepare granular reduced silver powder having an average particle size of 1 μm. Then, using this carbitol acetate solution of stearic acid as a lubricant, the reduced silver powder was crushed in a ball mill, and the silver powder surface-treated with stearic acid was washed with methanol to give an average particle size of 8 μm.
A flake-shaped silver powder having a size of m was prepared.

400 parts by weight of this flake-like silver powder, 100 parts by weight of a dimethylvinylsiloxy group-capped dimethylpolysiloxane (vinyl group content 0.2% by weight) at both ends of a molecular chain having a viscosity of 2000 centipoises, and a molecular chain having a viscosity of 30 centipoises. Methyl hydrogen polysiloxane with trimethylsiloxy groups blocked at both ends (silicon atom-bonded hydrogen atom content = 1.5% by weight) 1 part by weight, 3-glycidoxypropyltrimethoxysilane 7 parts by weight, chloroplatinic acid and vinylsiloxane (The amount of platinum metal in the complex is 5 ppm in the composition) and phenylbutynol (the amount of 300 ppm in the composition) are uniformly mixed, and the conductive silicone rubber is added. A composition was prepared. The appearance of this conductive silicone rubber composition, the curability of the composition, the contact resistance and volume resistivity of the silicone rubber obtained by curing the composition, and the adhesiveness of the composition were measured. The results are shown in Table 2.

Example 3 Granular atomized silver powder obtained by the water atomization method was pulverized in a ball mill using a xylene solution of dimethylpolysiloxane capped with dimethylvinylsiloxy groups at both molecular chain ends and having a viscosity of 100 centipoise as a lubricant. After that, the silver powder surface-treated with the dimethylpolysiloxane was washed with xylene to prepare a flake-shaped silver powder having an average particle size of 10 μm.

960 parts by weight of this flaky silver powder, 100 parts by weight of a dimethylvinylsiloxy group-capped dimethylvinylsiloxy group (both vinyl group content = 0.2% by weight) at both ends of a molecular chain having a viscosity of 2000 centipoises, and a molecule having a viscosity of 30 centipoises. 1 part by weight of methylhydrogenpolysiloxane with trimethylsiloxy groups blocked at both ends of the chain (content of hydrogen atoms bonded to silicon atom = 1.5% by weight), 7 parts by weight of 3-glycidoxypropyltrimethoxysilane, chloroplatinic acid and vinylsiloxane And a phenylbutynol (an amount of which is 300 ppm in the present composition) of platinum metal in the complex (the amount of platinum metal in the complex is 5 ppm of the present composition) are uniformly mixed to obtain the present invention. A conductive silicone rubber composition was prepared. The appearance of this conductive silicone rubber composition,
The curability of the composition, the contact resistance and volume resistivity of the silicone rubber obtained by curing the composition, and the adhesiveness of the composition were measured. The results are shown in Table 1.

Example 4 20 g of silver nitrate was dissolved in 40 ml of water, and a 46% aqueous sodium hydroxide solution was added thereto to precipitate granular silver oxide. After reducing the granular silver oxide with formalin, washing,
Filtration was repeated to prepare granular reduced silver powder having an average particle diameter of 3 μm. Then, this reduced silver powder was pulverized in a ball mill by using a carbitol acetate solution of dimethylpolysiloxan end-capped with dimethylvinylsiloxy groups having a viscosity of 100 centipoise as a lubricant, and then surface-treated with the dimethylpolysiloxane. Washed with carbitol acetate, the average particle size is 4μm
To prepare a flake-shaped silver powder.

450 parts by weight of this flaky silver powder, dimethylpolysiloxane endblocked by dimethylvinylsiloxy groups at both molecular chain ends, and (CH ₃ ) _{3 having} a viscosity of 8,000 centipoise
SiO _1/2 unit and (CH ₂ = CH) (CH ₃ ) ₂ SiO _1/2
100 parts by weight of a mixture of units and a silicone resin consisting of SiO _4/2 units (vinyl group content = 0.8% by weight),
5 parts by weight of a methylhydrogenpolysiloxane with a viscosity of 30 centipoise and a trimethylsiloxy group blocked at both ends of the molecular chain (silicon atom-bonded hydrogen atom content = 1.5% by weight),
formula:

[Chemical 12] 10 parts by weight of an organosilicon compound represented by the following formula, a complex of chloroplatinic acid and vinylsiloxane (the amount of platinum metal in the complex is 5 ppm in the present composition), phenylbutynol (in the present composition, The amount of 300 ppm) was uniformly mixed to prepare the conductive silicone rubber composition of the present invention. The appearance of this conductive silicone rubber composition, the curability of the composition, the contact resistance and volume resistivity of the silicone rubber obtained by curing the composition, and the adhesiveness of the composition were measured. The results are shown in Table 1.

[Comparative Example 3] 20 g of silver nitrate was dissolved in 40 ml of water, and a 46% aqueous sodium hydroxide solution was added thereto to precipitate granular silver oxide. After reducing the granular silver oxide with formalin, washing,
Filtration was repeated to prepare granular reduced silver powder having an average particle diameter of 3 μm. Next, this reduced silver powder was crushed in a ball mill using stearic acid as a lubricant, and the silver powder surface-treated with stearic acid was washed with xylene to form a flake-shaped silver powder having an average particle size of 4 μm. Was prepared.

450 parts by weight of this flaky silver powder, dimethylpolysiloxane endblocked by dimethylvinylsiloxy groups at both molecular chain ends, and (CH ₃ ) _{3 having} a viscosity of 8,000 centipoise.
SiO _1/2 unit and (CH ₂ = CH) (CH ₃ ) ₂ SiO _1/2
100 parts by weight of a mixture of units and a silicone resin consisting of SiO _4/2 units (vinyl group content = 0.8% by weight),
5 parts by weight of a methylhydrogenpolysiloxane with a viscosity of 30 centipoise and a trimethylsiloxy group blocked at both ends of the molecular chain (silicon atom-bonded hydrogen atom content = 1.5% by weight),
formula:

[Chemical 13] 10 parts by weight of an organosilicon compound represented by the following formula, a complex of chloroplatinic acid and vinylsiloxane (the amount of platinum metal in the complex is 5 ppm in the present composition), phenylbutynol (in the present composition, The amount was 300 ppm) was uniformly mixed to prepare a conductive silicone rubber composition. The appearance of this conductive silicone rubber composition, the curability of the composition, the contact resistance and volume resistivity of the silicone rubber obtained by curing the composition, and the adhesiveness of the composition were measured. The results are shown in Table 2.

Example 5 20 g of silver nitrate was dissolved in 40 ml of water, and a 46% aqueous sodium hydroxide solution was added thereto to precipitate granular silver oxide. After reducing the granular silver oxide with formalin, washing,
Filtration was repeated to prepare granular reduced silver powder having an average particle size of 1 μm. Next, this reduced silver powder was pulverized in a ball mill using a methanol solution of vinyltrimethoxysilane as a lubricant, and the silver powder surface-treated with vinyltrimethoxysilane was washed with methanol to give an average particle diameter of 2 μm. To prepare a flake-shaped silver powder.

400 parts by weight of this flaky silver powder, 100 parts by weight of a dimethylvinylsiloxy group-capped dimethylvinylsiloxy group (both vinyl group content = 0.2% by weight) at both ends of a molecular chain having a viscosity of 2000 centipoise, and a molecule having a viscosity of 30 centipoise 1 part by weight of methylhydrogenpolysiloxane with trimethylsiloxy groups blocked at both ends of the chain (content of hydrogen atoms bonded to silicon atom = 1.5% by weight), 7 parts by weight of 3-glycidoxypropyltrimethoxysilane, chloroplatinic acid and vinylsiloxane And a phenylbutynol (an amount of which is 300 ppm in the present composition) of platinum metal in the complex (the amount of platinum metal in the complex is 5 ppm of the present composition) are uniformly mixed to obtain the present invention. A conductive silicone rubber composition was prepared. The appearance of this conductive silicone rubber composition,
The curability of the composition, the contact resistance and volume resistivity of the silicone rubber obtained by curing the composition, and the adhesiveness of the composition were measured. The results are shown in Table 1.

Example 6 The softening point was 90 ° C. and the average unit formula was:

[Chemical 14] A dendritic electrolytic silver powder having an average particle size of 10 μm is crushed in a ball mill using a carbitol acetate solution of methylphenyl silicone resin represented by as a lubricant, and then surface-treated with the above methylphenyl silicone resin. The silver powder was washed with xylene to give an average particle size of 12
A flaky silver powder having a size of μm was prepared.

400 parts by weight of silver powder surface-treated with the above methylphenyl silicone resin, viscosity 2000
Centipoise molecular chain both ends dimethylvinylsiloxy group blocked dimethylpolysiloxane (vinyl group content = 0.2
100 parts by weight, viscosity of 30 centipoise, both ends of the molecular chain blocked with trimethylsiloxy groups, methylhydrogenpolysiloxane (silicon atom-bonded hydrogen atom content = 1.
5 parts by weight), 1 part by weight, 7 parts by weight of 3-glycidoxypropyltrimethoxysilane, a complex of chloroplatinic acid and vinyl siloxane (in this composition, platinum metal in the complex is 5 pp
It is the amount that becomes m. ) And phenylbutynol (the amount of which is 300 ppm in the present composition) are uniformly mixed to prepare the conductive silicone rubber composition of the present invention. The appearance of this conductive silicone rubber composition, the curability of the composition, the contact resistance and volume resistivity of the silicone rubber obtained by curing the composition, and the adhesiveness of the composition were measured. The results are shown in Table 1.

Example 7 100 g of flaky reduced silver powder having an average particle size of 4 μm was charged into a flask, and 170 g of heptane and 0.5 g of tetrabutyl titanate were added thereto.
Then, 5 g of trimethylethoxysilane was added, the mixture was stirred at room temperature for 4 hours, and then the silver powder was filtered. Next, the silver powder surface-treated with trimethylethoxysilane was washed with methanol, and then dried at 35 ° C. for 48 hours to prepare flaky silver powder having an average particle size of 4 μm.

400 parts by weight of silver powder surface-treated with the above-mentioned trimethylethoxysilane, 100 parts by weight of dimethylpolysiloxane (vinyl group content = 0.2% by weight) capped with dimethylvinylsiloxy groups at both molecular chain terminals having a viscosity of 2000 centipoises. , 1 part by weight of a methylhydrogenpolysiloxane having a trimethylsiloxy group blocked at both ends of the molecular chain and having a viscosity of 30 centipoise (silicon atom-bonded hydrogen atom content = 1.5% by weight), 7 parts by weight of 3-glycidoxypropyltrimethoxysilane, A complex of chloroplatinic acid and vinyl siloxane (in the present composition, the amount of platinum metal in the complex is 5 ppm) and phenylbutynol (in the present composition, 300 ppm) are uniformly added. By mixing, the conductive silicone rubber composition of the present invention was prepared.
The appearance of this conductive silicone rubber composition, the curability of the composition, the contact resistance and volume resistivity of the silicone rubber obtained by curing the composition, and the adhesiveness of the composition were measured. The results are shown in Table 1.

Example 8 Reduced silver having an average particle size of 1 μm or less prepared by reducing from silver nitrate using a carbitol acetate solution of dimethylpolysiloxane capped with dimethylvinylsiloxy groups at both ends of a molecular chain having a viscosity of 100 centipoise as a lubricant. It was crushed with a ball mill. After crushing, the silver powder was washed with xylene to remove excess dimethylpolysiloxane attached to the surface of the silver powder to prepare flake-shaped silver powder having an average particle size of 4 μm.

400 parts by weight of this flake-like silver powder, 100 parts by weight of dimethylpolysiloxane having a dimethylvinylsiloxy group blocked at both ends of a molecular chain having a viscosity of 2000 centipoise (vinyl group content = 0.2% by weight), and a molecule having a viscosity of 30 centipoise. 1 part by weight of a methylhydrogenpolysiloxane having trimethylsiloxy groups blocked at both chain ends (silicon atom-bonded hydrogen atom content = 1.5% by weight), a complex of chloroplatinic acid and vinylsiloxane (in the composition, platinum in the complex) The amount of metal was 5 ppm) and phenylbutynol (the amount of 300 ppm in the present composition) were uniformly mixed to prepare the conductive silicone rubber composition of the present invention. The appearance of this conductive silicone rubber composition,
The curability of the composition, the contact resistance and volume resistivity of the silicone rubber obtained by curing the composition, and the adhesiveness of the composition were measured. The results are shown in Table 1.

Comparative Example 4 Reduced silver having an average particle size of 3 μm or less prepared by reducing silver nitrate with hydrazine using stearic acid as a lubricant was pulverized with a ball mill. After crushing, the silver powder is washed with xylene to remove excess stearic acid adhering to the surface of the silver powder, and the average particle size is 4 μm.
A flake-shaped silver powder of m was prepared.

400 parts by weight of this flake-like silver powder, 100 parts by weight of dimethylpolysiloxane (vinyl group content = 0.2% by weight) capped with dimethylvinylsiloxy groups at both molecular chain terminals having a viscosity of 2000 centipoise, and a molecule having a viscosity of 30 centipoise. 1 part by weight of a methylhydrogenpolysiloxane having trimethylsiloxy groups blocked at both chain ends (silicon atom-bonded hydrogen atom content = 1.5% by weight), a complex of chloroplatinic acid and vinylsiloxane (in the composition, platinum in the complex) A conductive silicone rubber composition was prepared by uniformly mixing metal in an amount of 5 ppm) and phenylbutynol (in the present composition, an amount of 300 ppm). The appearance of this conductive silicone rubber composition, the curability of the composition, the contact resistance and volume resistivity of the silicone rubber obtained by curing the composition, and the adhesiveness of the composition were measured. The results are shown in Table 2.

Example 9 Average particle size 1 prepared by reducing silver nitrate with vinyltrimethoxysilane as a lubricant
Reduced silver having a size of μm or less was crushed with a ball mill. After crushing
The silver powder was washed with xylene to remove excess vinyltrimethoxysilane attached to the surface of the silver powder to prepare flake-shaped silver powder having an average particle size of 2 μm.

480 parts by weight of this flaky silver powder, 100 parts by weight of dimethylpolysiloxane (vinyl group content = 0.2% by weight) capped with dimethylvinylsiloxy groups at both molecular chain terminals having a viscosity of 2000 centipoise, and a molecule having a viscosity of 30 centipoise 3 parts by weight of methylhydrogenpolysiloxane with trimethylsiloxy group blocked at both ends of the chain (content of hydrogen atoms bonded to silicon atom = 1.5% by weight), formula:

[Chemical 15] 14 parts by weight of the organosilicon compound represented by the following formula, a complex of chloroplatinic acid and vinylsiloxane (the amount of platinum metal in the complex is 10 ppm in the present composition), phenylbutynol (in the present composition, 400 ppm) was uniformly mixed to prepare the conductive silicone rubber composition of the present invention. The appearance of this conductive silicone rubber composition, the curability of the composition, the contact resistance and volume resistivity of the silicone rubber obtained by curing the composition, and the adhesiveness of the composition were measured. The results are shown in Table 1.

Comparative Example 5 Reduced silver having an average particle size of 3 μm or less prepared by reducing silver nitrate with hydrazine using stearic acid as a lubricant was pulverized with a ball mill. After crushing, the silver powder is washed with xylene to remove excess stearic acid adhering to the surface of the silver powder, and the average particle size is 4 μm.
A flake-shaped silver powder of m was prepared.

480 parts by weight of this flaky silver powder, 100 parts by weight of a dimethylvinylsiloxy group-capped dimethylvinylsiloxy group (both vinyl group content = 0.2% by weight) at both molecular chain ends having a viscosity of 2000 centipoises, and a molecule having a viscosity of 30 centipoises. 3 parts by weight of methylhydrogenpolysiloxane with trimethylsiloxy group blocked at both ends of the chain (content of hydrogen atoms bonded to silicon atom = 1.5% by weight), formula:

[Chemical 16] 14 parts by weight of the organosilicon compound represented by the following formula, a complex of chloroplatinic acid and vinylsiloxane (the amount of platinum metal in the complex is 10 ppm in the present composition), phenylbutynol (in the present composition, 400 ppm) was uniformly mixed to prepare a conductive silicone rubber composition. The appearance of this conductive silicone rubber composition, the curability of the composition, the contact resistance and volume resistivity of the silicone rubber obtained by curing the composition, and the adhesiveness of the composition were measured. The results are shown in Table 2.

[Example 10] Average unit formula with a softening point of 90 ° C:

[Chemical 17] 25. Reduced silver having an average particle size of 2 μm or less prepared by reducing silver nitrate with hydrazine using a carbitol acetate solution of a phenyl group-containing silicone resin represented by
A mixture of 50% by weight and 75% by weight of atomized silver powder having an average particle size of 2 μm or less was pulverized with a ball mill. After crushing, the silver powder was washed with xylene to remove excess silicone resin adhering to the surface of the silver powder to prepare flake-shaped silver powder having an average particle size of 3 μm.

450 parts by weight of this flake-like silver powder, a dimethylpolysiloxane endblocked by dimethylvinylsiloxy groups at both molecular chain ends, and (CH ₃ ) _{3 having} a viscosity of 8,000 centipoise.
SiO _1/2 unit and (CH ₂ = CH) (CH ₃ ) ₂ SiO _1/2
100 parts by weight of a mixture of units and a silicone resin consisting of SiO _4/2 units (vinyl group content = 0.8% by weight),
formula:

[Chemical 18] 7 parts by weight of organopolysiloxane represented by the formula, 10 parts by weight of hydrophobic fumed silica, a complex of chloroplatinic acid and vinyl siloxane are dispersed in a thermoplastic silicone resin having a softening point of 80 to 90 ° C. to form a fine particle catalyst. (The amount of platinum metal in the catalyst is 10 ppm in this composition.) Is uniformly mixed to prepare the conductive silicone rubber composition of the present invention. The appearance of this conductive silicone rubber composition,
The curability of the composition, the contact resistance and volume resistivity of the silicone rubber obtained by curing the composition, and the adhesiveness of the composition were measured. The results are shown in Table 1.

[0072]

[Table 1]

[0073]

[Table 2]

[0074]

The conductive silicone rubber composition of the present invention contains, as the component (C), a silver powder surface-treated with an organosilicon compound, so that the composition has excellent storage stability and is cured. It is characterized in that the change in properties with time is small, and the change in volume resistivity of the conductive silicone rubber obtained by curing is small with time.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Satoshi Mine 2-2 Chikusaigan, Ichihara, Chiba Toray Dow Corning Silicone Co., Ltd.

Claims (3)

[Claims] 1. (A) 100 parts by weight of an organopolysiloxane having at least two alkenyl groups in one molecule, (B) an organopolysiloxane having at least two silicon-bonded hydrogen atoms in one molecule {( The blending amount of the component (B) is 0.5 to 3 silicon atom-bonded hydrogen atoms of the component (B) per one alkenyl group of the component (A). }, (C) 50 to 2000 parts by weight of silver powder surface-treated with an organosilicon compound, and (D) platinum-based catalyst {a sufficient amount to cure the present composition. } A conductive silicone rubber composition comprising: 2. (A) 100 parts by weight of organopolysiloxane having at least two alkenyl groups in one molecule, (B ') at least two silicon-bonded hydrogen atoms and at least one in one molecule. The amount of the organopolysiloxane having a silicon atom-bonded alkoxy group {(B ') component is such that the silicon atom-bonded hydrogen atom of the component (B') is 0 to one alkenyl group of the component (A). The amount is 0.5 to 3 pieces. }, (C) 50 to 2000 parts by weight of silver powder surface-treated with an organosilicon compound, and (D) platinum-based catalyst {a sufficient amount to cure the present composition. } A conductive silicone rubber composition comprising: 3. The component (C) is a silver powder obtained by pulverizing an organic silicon compound or an organic solvent solution of an organic silicon compound as a lubricant and pulverizing it.
The conductive silicone rubber composition described.