JP2699787B2 - Conductive silicone rubber composition and conductive silicone rubber - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-foaming or foaming conductive silicone rubber composition containing conductive carbon black and a cured non-foaming or foaming conductive silicone rubber. The present invention relates to a non-foaming or foaming conductive silicone rubber composition and a non-foaming or foaming conductive silicone rubber which can obtain a good rubber cured product even in a hot air vulcanization (HAV) method.

[0002]

2. Description of the Related Art
Insulation of conductive material mixed with rubber-like substance showing electrical insulation
Various types of conductive rubber are known, for example, as a conductive material.
Compounded with carbon black, etc., with an electric resistance of 10^Five~ 10
Conductive rubber in the range of Ω · cm is applied in a wide range of fields
ing.

[0003] On the other hand, silicone rubber, which is one of the electrically insulating rubber-like substances, has excellent heat resistance, cold resistance, and weather resistance, and is widely used as an electrically insulating rubber. By adding a conductive material such as carbon black to the, it has also been put to practical use as a conductive silicone rubber,
Further, a conductive silicone rubber foam foamed and cured by adding a foaming agent is also known.

In this case, the additive is added to the conductive silicone rubber.
Examples of conductive materials include carbon black and graphite.
Various metal powders such as fight, silver, nickel, copper, etc.
Electro-conductive powder or short fiber surface treated with metal such as silver, charcoal
A mixture of elementary fibers and metal fibers
Of the conductive material without damaging the unique characteristics of the
Volume resistivity of silicone rubber depends on type and filling amount
10^Ten~ 10^-3Because it can be reduced to about Ωcm
Frequently used, especially 10^FiveΩ ・ cm or less
When obtaining conductive silicone rubber,
Metal powders such as bon black, silver, nickel, etc.
From the viewpoint, a large amount of carbon black is used.

However, a conductive silicone rubber composition using carbon black such as acetylene black as a conductive material is continuously formed into a long material such as a seal material, a gasket material, and a roll material by extrusion molding or the like. When vulcanizing), the vulcanization system was very limited.

That is, for example, when an organic peroxide is vulcanized, the silicone rubber composition is usually vulcanized under normal pressure hot air (HA).
Benzoyl peroxide used in V), 2,4-
When an acyl peroxide such as dichlorobenzoyl peroxide is used in a system containing carbon black,
Vulcanization is not sufficiently performed due to the influence of carbon black, and a satisfactory molded product cannot be obtained. In addition, when an alkyl peroxide such as dicumyl peroxide or ditertiary butyl peroxide is used in a system containing carbon black, compression molding is possible, but the influence of oxygen in the air can be reduced by extrusion hot air vulcanization. However, there was a problem that the surface was not sufficiently vulcanized and the product was not satisfactory.

[0007] In order to overcome such difficulties, in the case of extruding a silicone rubber composition containing carbon black and vulcanizing it with hot air under normal pressure, a method of addition vulcanization has conventionally been generally employed. In this method, an alkenyl group-containing organopolysiloxane and an organohydrogenpolysiloxane having a silicon-bonded hydrogen atom that undergoes an addition reaction with the alkenyl group are cured by adding a platinum-based addition reaction catalyst.

However, this addition reaction method has a drawback in that the shelf life (storage time) is limited, the work life is short and the workability is poor, and it is not cured due to catalyst poisons such as amine, sulfur and tin. There is. In particular, gaskets for electromagnetic wave shielding materials using conductive silicone rubber, building gaskets, charging rolls, transfer rolls, developing rolls,
In the molding of conductive rolls for office use such as paper feed rolls and fixing rolls, and conductive calendering molded products such as for zebra connector molding, the above-mentioned molding by ordinary normal pressure hot air vulcanization involves molding properties and rubber obtained. Quality problem
These improvements have been desired.

When a conductive silicone rubber foam is obtained, in order to obtain a good foam, the vulcanization proceeds to a certain extent by additional vulcanization in order to confine the foaming gas generated by decomposition of the foaming agent in the system. (Scorch), it is necessary to search for an optimal control agent for controlling the addition reaction, and even if an appropriate control agent is used, an optimal control agent for obtaining a good foam can be obtained. The working time is limited to a very narrow time zone, and it is practically difficult to continuously produce a conductive silicone rubber foam by normal pressure hot air vulcanization by an addition reaction method. For this reason, there has been a demand for the development of a conductive silicone rubber foam composition that has a long pot life that can be used by a person engaged in sponge molding and that can be quickly vulcanized.

The present invention has been made in view of the above circumstances,
Conductive carbon black that has excellent storage stability and can be vulcanized by hot air vulcanization at normal pressure by extrusion or calendaring molding, and gives non-foamed or foamed silicone rubber with good moldability and good physical properties and conductivity. An object of the present invention is to provide a compounded non-foamable or foamable silicone rubber composition and a conductive non-foamable or foamed silicone rubber obtained by curing the composition.

[0011]

The present inventors have made intensive studies to achieve the above object, and as a result, have found that a conductive material containing an organopolysiloxane represented by the following general formula (1) and conductive carbon black: When an organic peroxide represented by the following general formula (2) is blended with the conductive silicone rubber composition, the conductive silicone rubber composition has the formula Since the organic peroxide shown in (2) is not affected by carbon black, it is well vulcanized by normal pressure hot air vulcanization or high frequency (UHF) vulcanization during extrusion molding and calendaring molding, and addition vulcanization. It was found that the resulting rubber cured product had good electrical conductivity and good physical properties, such as no surface tack, as well as good moldability.

[0012]

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[0013]

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Further, in this case, the above-mentioned conductive silicone rubber composition is treated with a fatty acid represented by the following general formula (4), an acid anhydride obtained by molecular condensation thereof, and an acid anhydride represented by the following general formula (5). It has been found that by adding one or more selected additives, the composition has high storage stability for a long period of time.

[0015]

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That is, in addition to the above-described organopolysiloxane represented by the general formula (1), conductive carbon black, and the organic peroxide represented by the general formula (2), the compound is represented by the general formula (4). The conductive silicone rubber composition containing one or two or more additives selected from fatty acids, acid anhydrides obtained by molecular condensation thereof, and acid anhydrides represented by the above general formula (5) comprises a conductive carbon black. Despite being blended, the organic peroxide represented by the formula (2) is not affected by carbon black, so that normal pressure hot air vulcanization or high frequency (UHF) vulcanization during extrusion molding or calendaring molding is performed. It is vulcanized better and does not rely on addition vulcanization, so there is no risk of catalyst poisoning, easy handling, good moldability, and a small change in plasticity over time after preparation of the composition, No coaches, stable workability over a long period of time, and found that the obtained cured silicone rubber has good conductivity and good physical properties without surface tack. .

Further, the organopolysiloxane of the general formula (1), the conductive carbon black, the general formula (2)
The conductive silicone rubber foam composition containing a foaming agent in addition to the above organic peroxide and, if necessary, the above-mentioned additives has a storage stability of 7 days or more, is extremely stable, and has a long pot life. It is also easy to perform normal pressure hot air vulcanization and high frequency (U
HF) It has been found that a vulcanization can be rapidly carried out by vulcanization to foam and harden, and that a conductive silicone rubber foam having good physical properties without surface tack and good conductivity can be obtained.

That is, the present inventors have made it possible for the organic peroxide of the above formula (2) to specifically enable normal pressure hot air vulcanization even in a carbon black blended system, and it is extremely stable at about normal temperature. It has been found that a vulcanizing action is quickly performed by heating, and the present invention has been accomplished.

Accordingly, the present invention provides a conductive material containing (a) an organopolysiloxane represented by the above formula (1), (b) conductive carbon black, and (c) an organic peroxide represented by the above formula (2). Silicone rubber composition, and (d)
A conductive silicone rubber composition containing an additive selected from the fatty acid of the above formula (4), an acid anhydride obtained by molecular condensation thereof, and an acid anhydride of the formula (5), and further containing (e) a foaming agent. Provided are a conductive silicone rubber composition, and a conductive silicone rubber obtained by curing the composition.

Hereinafter, the present invention will be described in more detail. The component (A) constituting the composition of the present invention is an organopolysiloxane represented by the following general formula (1).

[0021]

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Wherein R ¹ is a methyl group, an ethyl group,
Alkyl groups such as propyl group and butyl group, vinyl group, allyl group, alkenyl group such as butaniel group, phenyl group, aryl group such as tolyl group, or part or all of hydrogen atoms bonded to carbon atoms of these groups. A chloromethyl group, a chloropropyl group, a 3,3,3-trifluoropropyl group,
Same or different unsubstituted or substituted monovalent hydrocarbon groups selected from cyanoethyl groups and the like, preferably having 1 to 1 carbon atoms
0, more preferably 1 to 8, a is 1.90 to 2.
05 is a positive number.

This compound preferably has a linear molecular structure, but there is no problem even if the molecule contains a partially branched one. In addition, this may be one in which the molecular chain end is blocked with a triorganosilyl group or a hydroxyl group. Examples of the triorganosilyl group include a trimethylsilyl group, a dimethylvinylsilyl group, a methylphenylvinylsilyl group, and a methyldiphenylsilyl group. Group, methyldivinylsilyl group, trivinylsilyl group and the like. In this case, both ends of the molecular chain in order to further reduce the surface tack _{(CH 2 = CH) 2 RSi} -, (CH 2 = C
H) ₃ Si- (R is preferably set to that of multi-functional groups, such as showing the same meaning as R ^1). Although the degree of polymerization is not particularly limited, it has a viscosity at 25 ° C. of 30.
Those having 0 cs or more are preferred.

As the conductive carbon black constituting the component (b) of the present invention, those commonly used in conductive rubber compositions can be used. For example, acetylene black, conductive furnace black (CF), superconductive furnace black (SCF), extra conductive furnace black (XC
F), conductive channel black (CC), furnace black or channel black heat-treated at a high temperature of about 1500 ° C., and the like.

Specific examples of acetylene black include electrified acetylene black (manufactured by Denki Kagaku Co., Ltd.) and Shaunigan acetylene black (manufactured by Shaunigan Chemical Co., Ltd.). Specific examples of the conductive furnace black include Continex CF ( Continental Carbon Co., Ltd.), Vulcan C (Cabot Co., Ltd.)
Specific examples of the superconductive furnace black include Continex SCF (manufactured by Continental Carbon Co., Ltd.) and Vulcan SC (manufactured by Cabot Corporation). Specific examples of the extra-conductive furnace black include Asahi HS-500 (Asahi Carbon). And Vulcan XC-72 (Cabot Corporation), and Colux L (Degussa Corporation) as the conductive channel black.
Ketjen Black EC and Ketjen Black EC-600JD (Ketjen Black International Co., Ltd.), which are a kind of furnace black, can also be used.

Among these, acetylene black is particularly excellent in conductivity because it has a low impurity content and has a developed secondary structure, and is particularly preferably used in the present invention. Furthermore, Ketjen Black EC and Ketjen Black EC, which have an excellent specific surface area and exhibit excellent conductivity even at a low filling amount.
600 JD and the like can also be preferably used.

The amount of the conductive carbon black to be added is preferably 5 to 100 parts with respect to 100 parts (parts by weight, hereinafter the same) of the above-mentioned organopolysiloxane component.
Preferably it is 70 parts. If the added amount is less than 5 parts, desired conductivity may not be obtained in some cases. If the added amount exceeds 100 parts, the cured product may have poor mechanical strength in some cases.

As the component (c) of the composition of the present invention, an organic peroxide represented by the following formula (2) is used.

[0029]

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Here, in the formula, R ² and R ³ are n-propyl, isopropyl, t-butyl, n-butyl, n
-Amyl group, t-amyl group, hexyl group, heptyl group,
Octyl group, 2-ethylpropyl group, 2-ethylbutyl group, 2-ethylhexyl group, a monovalent hydrocarbon group having 3 to 10 carbon atoms such as cumyl group, or the formula -Si (R ⁴⁾
₃ (wherein R ⁴ is a methyl group, an ethyl group or a phenyl group), a trimethylsilyl group, a triethylsilyl group or a triphenylsilyl group, wherein R ² and R ³ are the same or different. You may. Further, n is an integer of 1 to 4.

The organic peroxide of the component (c) acts as a vulcanizing agent for the organopolysiloxane of the component (a) as described above. 0.1 to 5 parts per part,
In particular, it is preferably in the range of 0.5 to 3 parts. 0.1
If the amount is less than 5 parts, the vulcanization is not sufficient, the desired properties cannot be obtained, and it may not be practically usable. May be expensive.

The conductive silicone rubber composition of the present invention comprises:
In addition to the components (a) to (c) described above, in order to further improve the storage stability, as the component (d), a fatty acid represented by the following general formula (4), an acid anhydride obtained by molecular condensation thereof, and the following general formula One or more kinds selected from the acid anhydrides represented by (5) can be blended.

[0033]

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Here, R ⁵ is a hydrogen atom or a saturated or unsaturated, substituted or unsubstituted hydrocarbon group having 1 to 30, preferably 5 to 20 carbon atoms, wherein the hydrocarbon group is an octyl group. , Nonyl group, lauryl group, cetyl group, stearyl group, behenyl group and the like. Also,
m is an integer of 1 to 10, preferably 1 to 5.

Specific examples of the fatty acid represented by the general formula (4) include fatty acids such as formic acid, acetic acid, propionic acid, lauric acid, stearic acid, ricinoleic acid, naphthenic acid and 2-ethylhexoylic acid. No. Also,
Examples of the acid anhydride obtained by molecular condensation of these fatty acids include acetic anhydride.

R ⁶ is a saturated or unsaturated C 1 -C 1
30, preferably 2 to 10 substituted or unsubstituted polyvalent hydrocarbon groups. Examples of the formula (5) include maleic anhydride and phthalic anhydride. Here, p is an integer of 1 to 3.

The amount of the additive of the component (d) is not particularly limited, but is preferably 0.01 to 5 parts, particularly 0.1 to 1 part, per 100 parts of the total amount of the components (a) to (c). Is preferred.

Further, a foaming agent may be added to the composition of the present invention as a component (e) in order to form a molded article obtained from the composition of the present invention into a foam. The foaming agent is not particularly limited as long as it is stable at room temperature and releases a foaming gas when exposed to a high temperature. This foaming gas is generally preferably nitrogen gas, but may be carbon dioxide or another gas. Commercially available products can be used as the foaming agent. Amides such as amides having a decomposition temperature of 80 to 300 ° C can be suitably used. The amount of the foaming agent (e) is preferably 1 to 10 parts, more preferably 3 to 7 parts, per 100 parts of the organopolysiloxane (a).

The conductive silicone rubber composition of the present invention contains, in addition to the above-mentioned components, ΔSiH in one molecule in order to improve the surface tackiness when the foamed composition of the present invention is subjected to atmospheric hot air vulcanization. It is effective to mix an organic silicon compound having at least one bond as the component (f).

This organosilicon compound is usually used in a linear or cyclic form, but may contain a small amount of a branched structure or a three-dimensional structure. Are methylhydrogenpolysiloxanes of various degrees of polymerization blocked with trialkylsilyl groups, Si [OSi
Organopentasiloxane represented by (CH ₃ ) ₂ H] ₄ , siloxane copolymer composed of SiO ₂ units and (CH ₃ ) ₂ HSiO _0.5 units, copolymer of methyl hydrogen polysiloxane and dialkyl siloxane, SiH Examples thereof include a polysilylalkylene siloxane containing a bond, polysilane, and polycarbosilane.

The amount of the organosilicon compound of component (f) is from 0 to 10 parts, more preferably from 0.05 to 10 parts, especially from 0.5 to 10 parts, per 100 parts of the organopolysiloxane of component (a). Preferably it is 5 parts. If the amount is less than 0.05 part, the effect of the compounding may not be exhibited,
If the amount exceeds the range, physical properties such as heat resistance of the cured product may be reduced.

The composition of the present invention can be obtained by uniformly mixing predetermined amounts of the above-mentioned components. The order of blending these components is not particularly limited, but usually, the organopolysiloxane of component (a) is added to (b) The conductive carbon black of the component is mixed, and if necessary, the component (d) and the organic silicon compound of the component (f) are added, and then the organic peroxide of the component (c) is added. When the composition is made foamable, it can be prepared by further adding a foaming agent as the component (e) to the above-mentioned composition, and mixing the mixture by kneading with a Banbury mixer or a roll.

The composition of the present invention may contain a dispersant such as a low molecular weight siloxane having a degree of polymerization of 100 or less, a silanol group-containing silane, an alkoxy group-containing silane or the like, iron oxide, cerium oxide, iron octylate, etc., if necessary. Fumed silica, heat-resistant improver, pigment, etc.
Wet silica, fumed silica whose surface has been hydrophobized or wet silica, fine powder silica such as quartz fine powder, diatomaceous earth, etc. may be blended.Furthermore, isoparaffin is added for the purpose of imparting processability and moldability to the composition. It is also possible to add a saturated aliphatic hydrocarbon such as a solvent and other additives which are added to a usual silicone rubber composition.

The conductive silicone rubber composition of the present invention obtained as described above is molded by compression molding, injection molding, and calendaring molding, and then vulcanized well by normal-pressure hot air vulcanization to form an elastic material. Become. The vulcanization is carried out for a long time even at a low temperature.
It is possible to adopt a condition of 5 seconds to 10 minutes at a temperature of up to 500 ° C., a method of using heating by an infrared heater in addition to hot air, or a UHF (high frequency) absorption characteristic because carbon black is blended. It is also effective to use a normal pressure hot air vulcanization method used in combination with UHF heating.

The elastic body which is a cured product of the composition of the present invention thus formed is a conductive silicone rubber which is free from voids and surface tack and has excellent heat resistance. Therefore, the conductive silicone rubber composition of the present invention is EMI shielding gasket material, building gasket material, conductive roll member such as charging roll, transfer roll, developing roll, paper feed roll, fixing roll and the like.

Further, a conductive shell foamed by adding a foaming agent is used.
Silicone rubber foam has no voids or surface tack and is heat resistant
Since it is excellent in expandability, the foamable conductive silicone of the present invention is used.
The cone rubber composition is used as an electromagnetic wave shielding material,
G, and the resistivity is 10^Three~ 10^TenΩ ・ cm level
Sponge rolls in the semiconductive region of, for example, charging rolls, rolls
Copy roll, developing roll, paper feed roll, fusing roll,
Sponge sheet such as pressure roll or antistatic mat
It can be suitably used for sheets and the like.

[0047]

EXAMPLES The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to the following examples. In the following examples, parts are parts by weight, and viscosity is a value measured at 25 ° C.

Examples 1 and 2 and Comparative Examples 1 and 2 consist of 99.7% by mole of dimethylsiloxane unit and 0.275% by mole of methylvinylsiloxane unit, and have both ends of a dimethylvinylsilyl group of 0.025% by mole. Mol% blocked organopolysiloxane 100 having a viscosity of 1 × 10 ⁷ cs
Parts, 40 parts of acetylene black and 1 part of cerium oxide were kneaded using a pressure kneader, and then 100 parts of the base compound was blocked with a peroxide and a molecular chain terminal shown in Table 1 by a trimethylsilyl group. Methyl hydrogen polysiloxane containing 1.6 mol / 100 g of SiH bond was added to prepare a silicone rubber composition.

Next, these compositions were extruded into a rod having a diameter of 5 mm by an extruder having a diameter of 40 mm, and the extruder was heated at a temperature of 2 mm.
The mixture was passed through a normal pressure hot air vulcanization tower having a height of about 1 m at 50 ° C., and subjected to normal pressure hot air vulcanization with a residence time of 5 minutes.

The resulting conductive silicone rubber was measured for surface tackiness, hardness (JIS A), and volume resistivity. The results are also shown in Table 1.

[0051]

[Table 1]

From the results shown in Table 1, it can be seen that the compound containing the organic peroxide according to the present invention (Example) was vulcanized well despite the compounding of carbon black and had no surface tack and volume resistance. It is noted that it gives a low percentage of silicone rubber. On the other hand, it is recognized that the one containing a conventional peroxide (Comparative Example) was not vulcanized due to the influence of carbon black, or was insufficiently vulcanized.

Examples 3 and 4 and Comparative Examples 3 and 4 consist of 99.7% by mole of dimethylsiloxane unit and 0.275% by mole of methylvinylsiloxane unit, and have both ends of a dimethylvinylsilyl group of 0.025%. Mol% blocked organopolysiloxane 100 having a viscosity of 1 × 10 ⁷ cs
Parts, 40 parts of acetylene black and 1 part of cerium oxide were kneaded using a pressure kneader, and 100 parts of the base compound was added to a peroxide shown in Table 1 (A to A above).
C) A foamable composition is prepared by adding a methylhydrogenpolysiloxane containing 1.6 mol / 100 g of ≡SiH bonds in which both ends of the molecular chain are blocked by trimethylsilyl groups and azobisisobutyronitrile as a foaming agent. did.

Next, these compositions were continuously extruded into a rod having a diameter of 5 mm by an extruder having a diameter of 40 mm.
The mixture was placed in a normal pressure hot air vulcanizer having a temperature of 250 ° C. and a length of about 3 m, and the normal pressure hot air vulcanization was performed for a residence time of about 5 minutes.

With respect to the obtained conductive silicone rubber foam, the surface tackiness, expansion ratio, and hardness (Asker C) were measured. The results are also shown in Table 2.

[0056]

[Table 2]

From the results shown in Table 2, it can be seen that the compound containing the organic peroxide according to the present invention (Example) is excellent in vulcanization despite the compounding of carbon black and has no surface tack. It is recognized to give silicone rubber foam. On the other hand, it is recognized that the one containing a conventional peroxide (Comparative Example) was not vulcanized due to the influence of carbon black, or was insufficiently vulcanized.

Example 5, Comparative Example 5 The composition of the present invention (Example 5) in which the base compound used in Examples 3 and 4 was blended with an organic peroxide according to the formulation shown in Table 3 and a comparative example A vulcanization-based composition (Comparative Example 5) was prepared as
Extrusion foaming was carried out in the same manner as in Examples 3 and 4, and the pot life of the composition at that time was examined. The results are also shown in Table 3.

[0059]

[Table 3]

From the results shown in Table 3, the composition of the present invention was usable without any problem for 7 days immediately after preparation, but the addition vulcanization type composition of Comparative Example 5 had a very long pot life of 4 hours. And the long pot life of the composition of the present invention was confirmed.

[Examples 6 to 8, Comparative Example 6] Consisting of 99.7% by mole of dimethylsiloxane unit and 0.275% by mole of methylvinylsiloxane unit, both ends of the molecular chain being 0.025% by mole of dimethylvinylsilyl group. After kneading 100 parts of an organopolysiloxane having a viscosity of 1 × 10 ⁷ centistokes, 40 parts of acetylene black and 1 part of cerium oxide with a pressure kneader, 100 parts of the base compound is subjected to the above-mentioned peroxide treatment. Compound A and the additives shown in Table 4 were added to prepare a silicone rubber composition.

Next, the plasticity of these compositions was measured according to JIS-
After measuring with C-2123, and forming a sheet and covering with a polyethylene sheet, the plasticity after leaving at room temperature for 1 day and 3 days was similarly measured, and the extrudability was examined.

On the other hand, a rod having a diameter of 5 mm was extruded from the prepared silicone rubber composition with an extruder having a diameter of 40 mm, and passed through a normal pressure hot air vulcanization tower having a temperature of 250 ° C. and a height of about 1 m, and a residence time of 5 minutes. At room temperature for hot air vulcanization.

About the obtained conductive silicone rubber,
According to IS-K-6301, surface tackiness and hardness (JIS
-A), tensile strength and elongation were measured. The above results are shown in Table 4.

[0065]

[Table 4]

As is clear from the results shown in Table 4, the composition of the present invention (Example) to which stearic acid, acetic anhydride and maleic anhydride were added as additives was compared with the composition without addition (Comparative Example). It is recognized that the plasticity is stable for a long time, there is no scorch, and the processability is good. In addition, it is recognized that the cured products obtained in the examples have the same physical properties as those in the case of no addition (comparative example).

[0067]

As described above, the conductive silicone rubber composition of the present invention can be subjected to normal-pressure hot air vulcanization with an organic peroxide even though it contains carbon black. In addition, the resulting conductive silicone rubber has no voids or surface tack, and has excellent heat resistance and conductivity, so that it can be suitably used for various applications. In addition, the foamable composition of the present invention to which a foaming agent is added has good storage stability and a long pot life.

Claims (4)

(57) [Claims] (1) An organopolysiloxane represented by the following general formula (1): (B) conductive carbon black, (c) an organic peroxide represented by the following general formula (2), A conductive silicone rubber composition comprising: 2. The composition according to claim 1, wherein (d) a fatty acid represented by the following general formula (4), an acid anhydride obtained by molecular condensation thereof, and an acid anhydride represented by the following general formula (5): A conductive silicone rubber composition containing one or more additives. Embedded image 3. A conductive silicone rubber composition comprising the composition according to claim 1 and a foaming agent. 4. A conductive silicone rubber obtained by curing the composition according to claim 1, 2, or 3.