JP2006052302A - Electroconductive silicone rubber composition and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a conductive silicone rubber composition having a slight variation of electrical resistivity in a low conductive and a semiconductive region and small compression set and to provide a method for producing the composition. <P>SOLUTION: The conductive silicone rubber composition comprises (A) a liquid organopolysiloxane containing at least two alkenyl groups bound to the silicon atom in one molecule and having ≥800 degree of polymerization, (B) a crude rubber-like organopolysiloxane containing at least two alkenyl groups bound to the silicon atom in one molecule and having ≥2,000 degree of polymerization, (C) an organohydrogenpolysiloxane containing at least two hydrogen atoms bound to the silicon atom in one molecule, (D) carbon black and (E) an addition reaction catalyst and is liquid at room temperature. The method for producing the conductive silicone rubber composition comprises pre-mixing the total amount of the component (B) with the total amount of the component (D) and a part of the component (A) and then adding the residual amount of the component (A) and the components (C) and (E) and further mixing the components. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a conductive silicone rubber composition that is liquid at room temperature, and a method for producing the same, in which a cured rubber having a small change in electrical resistivity depending on the production lot and a small compression set can be obtained.

  Conventionally, various conductive rubbers in which a conductive material is blended with a rubber-like substance exhibiting electrical insulation properties are known. For example, carbon black or the like is blended as a conductive material, and the electrical resistivity is 10Ω · m to 10 kΩ · Conductive rubber having a range of m is applied in a wide range of fields.

  On the other hand, silicone rubber, which is one of the electrically insulating rubbery substances, is excellent in heat resistance, cold resistance and weather resistance, and is widely used as an electrically insulating rubber, but it is conductive like other rubbery substances. It is also put into practical use as a conductive rubber by adding materials. Further, as a method for stabilizing the resistance value, a method of blending conductive zinc white in JP-A-8-20725 (Patent Document 1) and JP-A-3-1955752 (Patent Document 2) are described. As you can see, the addition of silicone powder is known. However, these were all blended with silicone millable rubber and were not effective in the liquid composition.

Examples of the conductive material added to the conductive silicone rubber include various metal powders such as carbon black, graphite, silver, nickel and copper, various non-conductive powders, and short fiber surfaces treated with a metal such as silver. A mixture of carbon fiber, metal fiber, etc. has an electrical resistivity of 10 MΩ · m to 10 ⁻¹ depending on the type and filling amount of the conductive material without impairing the unique properties of silicone rubber. It is frequently used because it can be reduced to about Ω · m.

  However, when these various carbon blacks and metal powders are blended with liquid silicone rubber, the variation in electrical resistivity becomes extremely large in the low conductive and semiconductive regions of 10 MΩ · m to 10Ω · m, and the electrical resistivity is stabilized. It was difficult. This is considered to be because the dispersibility of the conductive particles varies significantly depending on the molding conditions.

  In recent years, however, low conductivity and semi-conductive materials are used as rubber rolls for OA equipment parts, particularly charging rolls, development rolls, paper feed rolls, fixing rolls, pressure rolls, static elimination rolls, cleaning rolls, oil application rolls, etc. There is a growing need for conductive rolls, and there is a need for conductive rolls that exhibit stable electrical resistivity with little variation in electrical resistivity in this region.

JP-A-8-20725 Japanese Patent Laid-Open No. 3-195552

  The present invention has been made in view of the above circumstances, and provides a conductive silicone rubber composition having a small variation in electrical resistivity in a low conductive and semiconductive region and a small compression set, and a method for producing the same. Objective.

  As a result of intensive studies to achieve the above object, the present inventor, as a result of addition reaction curable liquid organopolysiloxane composition, in addition to carbon black as a conductive material, high molecular weight having an addition reactive group. By blending a siloxane polymer, a silicone rubber composition having a low volume conductivity of 10 MΩ · m to 10 Ω · m and a stable volume resistivity in a semiconductive region and having a small compression set can be obtained. By kneading together with the high molecular weight polymer, it was found that carbon black was sufficiently dispersed in siloxane and more stable conductivity was obtained, and the present invention was made.

Therefore, the present invention
(A) Liquid organopolysiloxane having a polymerization degree of 800 or less and containing an alkenyl group bonded to at least two silicon atoms in one molecule: 97 to 70 parts by mass,
(B) Raw rubber-like organopolysiloxane having a polymerization degree of 2,000 or more and containing an alkenyl group bonded to at least two silicon atoms in one molecule: 3 to 30 parts by mass
(However, the total of the components (A) and (B) is 100 parts by mass.)
(C) Organohydrogenpolysiloxane containing hydrogen atoms bonded to at least two silicon atoms in one molecule: 0.1 to 30 parts by mass
(D) Carbon black: 0.5 to 50 parts by mass,
(E) addition reaction catalyst: a conductive silicone rubber composition containing a catalytic amount and being liquid at room temperature, and the total amount of component (B) and the total amount of component (D) and (A) Provided is a method for producing the conductive silicone rubber composition, wherein a part of the components are mixed in advance, and then the remaining amount of the component (A) and the components (C) and (E) are added and further mixed. To do.

  The conductive silicone rubber composition of the present invention has stable electrical resistivity in the low conductivity and semiconducting regions, and is particularly stable with little variation in electrical resistivity due to production lots and low compression set. Therefore, it is suitable as a roll for an image forming apparatus, particularly as a material for a developing roll.

The conductive silicone rubber composition of the present invention is liquid at room temperature containing the following components (A) to (E).
(A) Organopolysiloxane containing an alkenyl group bonded to at least two silicon atoms in one molecule and having a polymerization degree of 800 or less (B) Containing an alkenyl group bonded to at least two silicon atoms in one molecule Organohydrogenpolysiloxane (D) carbon black (E) addition reaction catalyst containing hydrogen atoms bonded to at least two silicon atoms in one molecule of organopolysiloxane (C) having a polymerization degree of 2,000 or more

  As the organopolysiloxane containing an alkenyl group bonded to at least two silicon atoms in one molecule of the component (A), those represented by the following average composition formula (1) can be used.

R ¹ _a SiO _{(4-a) / 2} (1)
In the formula, R ¹ is an unsubstituted or substituted monovalent hydrocarbon group having the same or different carbon number of 1 to 10, preferably 1 to 8, and a is 1.5 to 2.8, preferably 1.8. It is a positive number in the range of ˜2.5, more preferably 1.95 to 2.05.

Here, as the unsubstituted or substituted monovalent hydrocarbon group bonded to the silicon atom represented by R ¹ , a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, Pentyl group, neopentyl group, hexyl group, cyclohexyl group, octyl group, nonyl group, alkyl group such as decyl group, aryl group such as phenyl group, tolyl group, xylyl group, naphthyl group, benzyl group, phenylethyl group, phenylpropyl Aralkyl groups such as groups, vinyl groups, allyl groups, propenyl groups, isopropenyl groups, butenyl groups, hexenyl groups, cyclohexenyl groups, octenyl groups and other alkenyl groups, and some or all of the hydrogen atoms of these groups are fluorine. Substituted with halogen atoms such as bromine, chlorine, cyano groups, etc., such as chloromethyl group, chloropro Group, bromoethyl group, trifluoropropyl group, but cyanoethyl group and the like, Preferably, at least 90% of all R ¹ is a methyl group.

In addition, at least 2 (usually 2 to 50) of R ¹ , preferably 2 to 20, more preferably 2 to 10 are alkenyl groups (preferably having 2 to 8 carbon atoms, more preferably carbon. 2 to 6 and particularly preferably a vinyl group). The content of the alkenyl group is 1.0 × 10 ^{−5 to} 1.0 × 10 ⁻² mol / g, particularly 2.0 × 10 ^{−5 to} 5.0 × 10 ⁻³ mol / g in the organopolysiloxane. It is preferable that If the amount of the alkenyl group is less than 1.0 × 10 ⁻⁵ mol / g, the crosslinking may be insufficient and gelation may occur, and if the amount is more than 1.0 × 10 ⁻² mol / g, the crosslinking density is low. There is a possibility that the rubber becomes too high and becomes brittle rubber.

  The alkenyl group may be bonded to a silicon atom at the end of the molecular chain, may be bonded to a silicon atom in the middle of the molecular chain, or may be bonded to both.

The structure of the organopolysiloxane of the present invention basically consists of repeating diorganosiloxane units whose main chain portion is represented by R ¹ ₂ SiO _{2/2 and} whose molecular chain ends are represented by R ¹ ₃ SiO _1/2 . It preferably has a linear structure blocked with a triorganosiloxy group, but may be partially branched or cyclic.

  The organopolysiloxane has a molecular weight of 800 or less, preferably 100 to 700, and liquid at room temperature (25 ° C.) (usually 100 to 500,000 mPa · s at 25 ° C., preferably 1,000). ˜100,000 mPa · s). When the degree of polymerization exceeds 800, the viscosity becomes too high, resistance varies depending on the molding pressure, and molding itself becomes difficult. In addition, as a lower limit of a polymerization degree, it is preferable that it is 50 or more, especially 100 or more.

  Next, an organopolysiloxane having an average degree of polymerization of 2,000 or more and containing an alkenyl group bonded to at least two silicon atoms in one molecule of the component (B) is represented by the following average composition formula (2). Can be used.

R ² _b SiO _{(4-b) / 2} (2)
In the formula, R ² is the same or different, unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, preferably 1 to 8 carbon atoms, and b is 1.8 to 2.5, preferably 1.9. To 2.1, more preferably 1.95 to 2.05, and still more preferably a positive number in the range of 1.98 to 2.01.

Here, the unsubstituted or substituted monovalent hydrocarbon group bonded to the silicon atom represented by R ² includes a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, Pentyl group, neopentyl group, hexyl group, cyclohexyl group, octyl group, nonyl group, alkyl group such as decyl group, aryl group such as phenyl group, tolyl group, xylyl group, naphthyl group, benzyl group, phenylethyl group, phenylpropyl Aralkyl groups such as groups, vinyl groups, allyl groups, propenyl groups, isopropenyl groups, butenyl groups, hexenyl groups, cyclohexenyl groups, octenyl groups and other alkenyl groups, and some or all of the hydrogen atoms of these groups are fluorine. Substituted with halogen atoms such as bromine, chlorine, cyano groups, etc., such as chloromethyl group, chloropro Group, bromoethyl group, trifluoropropyl group, but cyanoethyl group and the like, it is preferable more than 90% of the total R ² is a methyl group.

In addition, at least 2 (usually 2 to 30) of R ² , preferably 2 to 20, more preferably 2 to 10 are alkenyl groups (preferably having 2 to 8 carbon atoms, more preferably carbon. 2 to 6 and particularly preferably a vinyl group). The alkenyl group content in the organopolysiloxane is 1.0 × 10 ^{−6 to} 1.0 × 10 ⁻² mol / g, particularly 5.0 × 10 ^{−6 to} 1.0 × 10 ⁻³ mol / g. It is preferable that If the amount of the alkenyl group is less than 1.0 × 10 ⁻⁶ mol / g, a polymer which has not reacted or has no crosslinking point may bleed after curing. On the other hand, when the amount is more than 1.0 × 10 ⁻² mol / g, the crosslinking density becomes too high and the rubber may be brittle.

  The alkenyl group may be bonded to a silicon atom at the end of the molecular chain, may be bonded to a silicon atom in the middle of the molecular chain, or may be bonded to both.

The structure of the organopolysiloxane of the present invention basically consists of repeating diorganosiloxane units whose main chain portion is represented by R ² ₂ SiO _{2/2 and} whose molecular chain ends are represented by R ² ₃ SiO _1/2 . It preferably has a linear structure blocked with a triorganosiloxy group, but may be partially branched or cyclic.

  The molecular weight of the organopolysiloxane should be a degree of polymerization of 2,000 or more, preferably 4,000 or more, and a raw rubber at room temperature (25 ° C.). When the degree of polymerization is less than 2,000, the thickening effect is insufficient, and it becomes difficult to sufficiently disperse carbon black and obtain a stable volume resistivity. In addition, as an upper limit of a polymerization degree, it is preferable that it is 30,000 or less, especially 20,000 or less.

  The blending amount of component (B), which is this raw rubber-like organopolysiloxane, is 3-30% by mass, preferably 5-25% by mass, based on the total amount of component (A) and component (B). . If the amount is less than 3% by mass, a sufficient thickening effect cannot be obtained. If the amount exceeds 30% by mass, the viscosity is too high and molding becomes difficult, and the compression set is also increased.

  The component (C) of the present invention is an organohydrogenpolysiloxane having at least 2, preferably 3 or more hydrogen atoms (Si-H groups) bonded to silicon atoms in one molecule. The H group crosslinks with the alkenyl group bonded to the silicon atom in the components (A) and (B) by a hydrosilylation addition reaction, and acts as a curing agent for curing the composition.

As the organohydrogenpolysiloxane of component (C), those represented by the following average composition formula (3) can be used.
R ³ _c H _d SiO _{(4-cd) / 2} (3)
(In the formula, R ³ is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, preferably 1 to 8 carbon atoms, c is 0.7 to 2.1, and d is 0.001 to 0.001. 1.0 and c + d is a positive number satisfying 0.8 to 3.0.)

Examples of the unsubstituted or substituted monovalent hydrocarbon group of R ^3, there may be mentioned the same ones as exemplified for R ^1, it is having no aliphatic unsaturated group (alkenyl group) Particularly preferred are a methyl group, a phenyl group, and a trifluoropropyl group. Further, c is preferably a positive number satisfying 0.8 to 2.0, d being 0.01 to 1.0, and c + d being 1.0 to 2.5.

  The organohydrogenpolysiloxane of the present invention has at least 2 (usually 2 to 300), preferably 3 or more (usually 3 to 100), more preferably 3 to 50 silicon atoms in one molecule. It has a bonded hydrogen atom (Si-H group).

  The silicon atom-bonded hydrogen atom (Si—H group) content is preferably 0.001 to 0.017 mol / g, particularly 0.002 to 0.015 mol / g in the organohydrogenpolysiloxane. If the amount of silicon atom-bonded hydrogen atoms (Si-H groups) is too small, crosslinking may be insufficient and gelation may occur, and if too large, the crosslinking density becomes too high, resulting in brittle rubber. There is a fear.

  In addition, the hydrogen atom (Si—H group) bonded to the silicon atom may be located at either the molecular chain end or in the middle of the molecular chain, or may be located at both.

  The molecular structure of the organohydrogenpolysiloxane of the present invention may be any of linear, cyclic, branched, and three-dimensional network structures. In this case, the number (or degree of polymerization) of silicon atoms in one molecule is 2 to 300, particularly about 4 to 150, at room temperature (25 ° C.) and liquid (usually 1,000 mPa · s or less at 25 ° C., preferably Is preferably about 0.1 to 500 mPa · s).

Examples of the organohydrogenpolysiloxane of the component (C) include 1,1,3,3-tetramethyldisiloxane, 1,3,5,7-tetramethylcyclotetrasiloxane, trimethylsiloxy group-blocked methylhydrogen at both ends. Polysiloxane, Trimethylsiloxy group-capped dimethylsiloxane / methylhydrogensiloxane copolymer, both ends dimethylhydrogensiloxy group-capped dimethylpolysiloxane, Both ends dimethylhydrogensiloxy group-capped dimethylsiloxane / methylhydrogensiloxane copolymer , Trimethylsiloxy group-capped methylhydrogensiloxane / diphenylsiloxane copolymer, both ends trimethylsiloxy group-capped methylhydrogensiloxane / diphenylsiloxane / dimethylsiloxane Hexane copolymer, and (CH _{3) 2} HSiO copolymer comprising a _1/2 units and SiO _4/2 units, and, (CH _{3) 2} HSiO _1/2 units and (CH _{3) 3} SiO _1/2 units Examples _thereof include a copolymer composed of SiO _4/2 units, a copolymer composed of (CH ₃ ) ₂ HSiO _1/2 units, SiO _4/2 units, and (C ₆ H ₅ ) SiO _3/2 units. .

  The compounding amount of the organohydrogenpolysiloxane is preferably 0.1 to 30 parts by mass, particularly preferably 0.3 to 20 parts by mass with respect to 100 parts by mass in total of the components (A) and (B). If the amount is less than 0.1 parts by mass, crosslinking is insufficient, and the desired physical properties of rubber as a roll cannot be obtained. If the amount exceeds 30 parts by mass, compression set increases. The amount of the organohydrogenpolysiloxane is the amount of silicon atom-bonded hydrogen atoms (Si-H groups) in the component (C) relative to the alkenyl groups bonded to silicon atoms in the components (A) and (B). Can be blended in an amount of usually 0.3 to 10.0, preferably 0.5 to 5.0, in molar ratio.

  As the carbon black of component (D), those usually used in conductive rubber compositions can be used, for example, acetylene black, conductive furnace black (CF), super conductive furnace black (SCF), extra conductive Examples thereof include furnace black (XCF), conductive channel black (CC), furnace black and channel black that have been heat-treated at a high temperature of about 1,500 ° C.

  Specifically, as acetylene black, electrified acetylene black (manufactured by Electrochemical Co., Ltd.), Shaunigan acetylene black (manufactured by Shaunigan Chemical Co., Ltd.), etc., and as conductive furnace black, Continex CF (manufactured by Continental Carbon) , Vulcan C (manufactured by Cabot), etc., Superconductive furnace black, Continex SCF (manufactured by Continental Carbon), Vulcan SC (manufactured by Cabot), etc., as extra-conductive furnace black, Asahi HS-500 ( Asahi Carbon Co., Ltd.), Vulcan XC-72 (Cabot Co., Ltd.), etc., examples of the conductive channel black include Kourax L (Degussa Co., Ltd.), and Ketjen, a kind of furnace black. It is also possible to use a rack EC and Ketchen black EC-600JD (manufactured by Ketchen Black International Co., Ltd.).

  Of these, acetylene black has a low impurity content and has a developed secondary structure structure, so that it has excellent conductivity and is particularly preferably used in the present invention. Moreover, Ketjen Black EC, Ketjen Black EC-600JD, etc. which show the outstanding electroconductivity also with the low filling amount from the outstanding specific surface area can be used preferably.

  These carbon blacks may be those subjected to surface hydrophobization treatment. Surface treatment agents include fatty acid esters such as ethyl stearate, organic titanates such as tetrabutyl titanate, silanes such as trialkoxyvinyl silane and silane coupling agents, silazanes such as hexamethyldisilazane, and hydroxy groups at both ends. Any known surface treatment agent may be used, such as organic functional group-containing siloxanes such as siloxane and low molecular silicones such as octamethylcyclotetrasiloxane.

  (B) As compounding quantity of carbon black which is a component, it is 0.5-50 mass parts with respect to 100 mass parts of organopolysiloxane total amount of (A) component and (B) component mentioned above, Preferably it is 1-30. It is 1 part by mass, more preferably 1 to 20 parts by mass. If the addition amount is less than 0.5 parts by mass, desired conductivity cannot be obtained. If the addition amount exceeds 50 parts by mass, not only the compounding is difficult, but also the physical properties of the rubber are significantly lowered. The blending amount of the component (D) is preferably such that the volume resistivity of the cured product (silicone rubber) of the silicone rubber composition is 10 MΩ · m to 10 Ω · m.

  The carbon black can be added and mixed simultaneously with the components (A) to (E). Preferably, however, liquid oil ( A method of adjusting the viscosity so as to be easily molded by adding (A) component liquid organopolysiloxane is preferred. Specifically, first, the total amount of carbon black, the total amount of raw rubber siloxane of component (B) and a part of liquid siloxane of component (A) are mixed, and the carbon black is sufficiently dispersed. At this time, a surface treatment agent may be added or mixed while heating at about 100 ° C. to 180 ° C. After mixing, the remaining component (A) and other components are added, and sufficiently stirred again to obtain a liquid silicone rubber composition having a desired viscosity.

  (E) Component addition reaction catalysts include platinum black, platinous chloride, chloroplatinic acid, a reaction product of chloroplatinic acid and a monohydric alcohol, a complex of chloroplatinic acid and olefins, platinum bisacetoacetate, Examples thereof include platinum group metal catalysts such as palladium catalysts and rhodium catalysts. In addition, although the compounding quantity of this addition reaction catalyst can be made into a catalyst quantity, it is 0.5-1,000 ppm with respect to the total mass of (A) component and (B) component normally as a metal component, especially 1- It is preferable to blend about 500 ppm.

  In the conductive silicone rubber composition of the present invention, if necessary, a reinforcing silica filler such as silica hydrogel (hydrous silicic acid), silica airgel (anhydrous silicic acid-fumed silica), clay, calcium carbonate, diatomaceous earth. Soil, filler such as titanium dioxide, low molecular siloxane ester, silanol, dispersant such as diphenylsilanediol, heat resistance improver such as iron oxide, cerium oxide, iron octylate, acetylene alcohol such as ethynylcyclohexanol, tetra Reaction control agents such as cyclic vinylsiloxanes such as vinyltetramethylcyclotetrasiloxane, triazole compounds such as benzotriazole, various carbon functional silanes for improving adhesion and moldability, halogen compounds that impart flame retardancy, etc. The purpose of the present invention is not impaired It may be added and mixed in circumference.

  The viscosity at room temperature (25 ° C.) of the conductive silicone rubber composition of the present invention is preferably 30 to 600 Pa · s, more preferably 50 to 500 Pa · s. If the viscosity is less than 30 Pa · s, the volume resistivity may not be stable. If the viscosity exceeds 600 Pa · s, the pressure during molding becomes too high, and the volume resistivity may not be stable. In the present invention, the viscosity can be measured by a rotational viscometer such as BH type and BS type.

  The volume resistivity of the silicone rubber obtained by curing the conductive silicone rubber composition of the present invention is preferably 10 MΩ · m to 10 Ω · m, more preferably 100 kΩ · m to 10 Ω · m. . When the volume resistivity is less than 10 Ω · m, the image may be unclear when used as a developing roll. When the volume resistivity is larger than 10 MΩ · m, the developing roll may not be used. Here, the volume resistivity can be measured according to SRIS (Japan Rubber Association Standard) 2301-1969.

  The conductive silicone rubber composition of the present invention that provides such a stable low conductivity and semiconductivity can be used for applications requiring various conductivity such as electrical / electronic components, automotive components, and office machine components. However, it is particularly suitably used as a roll for electrophotographic image forming apparatuses such as copying machines, printers, and facsimiles. Examples of such a roll include a charging roll, a developing roll, a transfer roll, and a fixing roll, and among them, it is particularly suitable for a developing roll.

  Here, as the developing roll, it is more effective to provide the conductive silicone rubber layer of the present invention on the outer periphery of the core body and further to have a surface layer in contact with the toner around it.

  The core is not particularly limited, and a solid or hollow core made of various metals and resins is used. For example, examples of the metal include iron, copper, white, stainless steel, etc. Examples include polyethylene, polyamide, polyacetal, polycarbonate, polyethylene terephthalate, polyimide, polyamideimide, polyester, phenol resin, epoxy resin, acrylic resin, and methacrylic resin.

The method for forming the silicone rubber layer on the outer periphery of the core body is not particularly limited, and a known method can be adopted. Generally, coating is performed on the core body, or the core body is previously placed in the center of the mold, There is a method in which a silicone rubber composition is molded between the mold wall surface and the core body by injection or injection. A primer or an adhesive layer may be provided between the core and the silicone rubber layer as necessary.
Here, the curing conditions for the silicone rubber composition are room temperature (25 ° C.) to 250 ° C., particularly 80 to 220 ° C. for 30 seconds to 4 hours, particularly 120 to 200 ° C. for 1 minute to 1 hour, and then 150 to Post-curing is preferably performed at 250 ° C., particularly 160 to 200 ° C. for 30 minutes to 12 hours, particularly 1 to 6 hours.

  Further, the surface layer in contact with the toner includes polyester resin, polyether resin, fluororesin, epoxy resin, polyamide resin, acrylic resin, acrylic urethane resin, urethane resin, alkyd resin, phenol resin, melamine resin, urea resin, and these And the like. If necessary, additives such as fillers such as carbon black, plasticizers such as oil, and charge control agents may be appropriately added to the surface layer. The method for forming the surface layer around the silicone rubber layer is not particularly limited, and for example, a coating method, an in-mold coating method, or a method in which a shrink tube previously formed in a cylindrical shape is coated by heating and shrinking is appropriately selected. The In addition, a primer layer and an adhesive layer can be provided between the silicone rubber layer and these surface layers as necessary.

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated concretely, this invention is not limited to the following Example. In the following examples, all parts are parts by mass.

[Example 1]
40 parts of dimethylpolysiloxane A (polymerization degree 600, vinyl group content 0.0001 mol / g) having both ends blocked with trimethylsiloxy groups and vinyl groups in the side chains, both ends blocked with trimethylsiloxy groups and side chains Hydrophobic fumed silica having 10 parts of raw rubber-like dimethylpolysiloxane B having a vinyl group (degree of polymerization 8,000, vinyl group content 0.00008 mol / g) and a specific surface area of 110 m ² / g by BET method (R-972, manufactured by Nippon Aerosil Co., Ltd.) 1 part and acetylene black (Denka Black HS-100, manufactured by Denki Kagaku Kogyo Co., Ltd.) 3 parts were put into a planetary mixer and stirred for 30 minutes. I passed through. After returning this to the planetary mixer, 50 parts of dimethylpolysiloxane A was further added, and stirring was continued for 30 minutes. Thereafter, 2.6 parts of methylhydrogenpolysiloxane having Si—H groups at both ends and side chains as a crosslinking agent (polymerization degree 17, Si—H amount 0.0060 mol / g), and ethynylcyclohexanol 0 as a reaction control agent 0.05 part and 0.1 part of platinum catalyst (Pt concentration 1%) were added and stirring was continued for 15 minutes to obtain a silicone rubber composition. The viscosity of this composition at room temperature (25 ° C.) was measured under the condition of 10 rpm using a BH viscometer and rotor No. 7, and the results are shown in Table 1.

  This silicone rubber composition was press-molded at 120 ° C. for 10 minutes and further subjected to post-cure with a dryer at 200 ° C. for 4 hours. Then, the rubber hardness, compression set, and volume resistivity were measured and listed in Table 1. . In addition, the hardness was measured according to JIS K6249 from a 2 mm sheet, and the compression set was measured from a cylindrical molded product having a diameter of 29 mm × height of 12.7 mm by 180% × 22 hours and 25% compression. The volume resistivity was measured according to SRIS (Japan Rubber Association Standard) 2301-1969. In addition, in order to see the variation in the volume resistivity depending on the production lot, the results of measuring the volume resistivity from the sheet produced 10 times by the same composition and the same production method and cured by the same method are shown in Table 2. (Ie, a total of 11 measurements were made only for volume resistivity).

[Example 2]
40 parts of dimethylpolysiloxane C (polymerization degree 200) blocked at both ends with dimethylvinylsiloxy groups, raw rubber-like dimethylpolysiloxane D (polymerization degree 5) with both ends blocked with trimethylsiloxy groups and vinyl groups in the side chains 000, vinyl group content 0.00022 mol / g) 20 parts, acetylene black (Denka Black HS-200, manufactured by Denki Kagaku Kogyo Co., Ltd.) 2.3 parts, white conductive titanium oxide ET-500W (produced by Ishihara Sangyo Co., Ltd.) ) 5 parts were put into a planetary mixer and stirred for 30 minutes, and then passed once through three rolls. Thereafter, the mixture was returned to the planetary mixer, 40 parts of dimethylpolysiloxane C was further added, and stirring was continued for 30 minutes. Thereafter, 4.0 parts of methylhydrogenpolysiloxane having a Si—H group only in the side chain as a crosslinking agent (polymerization degree 50, Si—H amount 0.0045 mol / g), 0.05% ethynylcyclohexanol as a reaction control agent Part, platinum catalyst (Pt concentration 1%) 0.1 part was added and stirring was continued for 15 minutes to obtain a silicone rubber composition. The viscosity of this composition at room temperature (25 ° C.) was measured under the condition of 10 rpm using a BH viscometer and rotor No. 7, and the results are shown in Table 1.

  The results of measuring the rubber hardness, compression set, and volume resistivity from this silicone rubber composition in the same manner as in Example 1 are shown in Table 1. Further, the volume resistivity according to the production lot is also shown in Table 2.

[Example 3]
40 parts of dimethylpolysiloxane A of Example 1 (degree of polymerization 600, vinyl group content 0.0001 mol / g), raw rubbery dimethylpolysiloxane B of Example 1 (degree of polymerization 8,000, vinyl group content 0.00008 mol) / G) 10 parts, 1 part of a hydrophobized fumed silica (R-972, manufactured by Nippon Aerosil Co., Ltd.) having a specific surface area of 110 m ² / g by BET method, acetylene black (Denka Black HS-100, Electrochemistry) 1.5 parts of Kogyo Kogyo Co., Ltd. and 0.5 part of Furnace Black (Ketjen EC600JD, Lion) were put in a planetary mixer, heated to 150 ° C., stirred for 1 hour, and then 1 in 3 rolls. I passed through. This was returned to the planetary mixer, cooled to room temperature, 50 parts of dimethylpolysiloxane C of Example 2 was further added, and stirring was continued for 30 minutes. Thereafter, 3.5 parts of methylhydrogenpolysiloxane having a Si—H group at both ends and side chains as a crosslinking agent (polymerization degree 17, Si—H amount 0.0060 mol / g), and ethynylcyclohexanol 0 as a reaction control agent 0.05 part and 0.1 part of platinum catalyst (Pt concentration 1%) were added and stirring was continued for 15 minutes to obtain a silicone rubber composition. The viscosity of this composition at room temperature (25 ° C.) was measured under the condition of 10 rpm using a BH viscometer and rotor No. 7, and the results are shown in Table 1.

  The results of measuring the rubber hardness, compression set, and volume resistivity from this silicone rubber composition in the same manner as in Example 1 are shown in Table 1. Further, the volume resistivity according to the production lot is also shown in Table 2.

[Comparative Example 1]
40 parts of dimethylpolysiloxane E having both ends blocked with trimethylsiloxy groups and vinyl groups in the side chains (polymerization degree 1,000, vinyl group content 0.00009 mol / g), raw rubber-like dimethylpolysiloxane B of Example 1 (Polymerization degree 8,000, vinyl group content 0.00008 mol / g) 10 parts, hydrophobized fumed silica having a specific surface area of 110 m ² / g by BET method (R-972, manufactured by Nippon Aerosil Co., Ltd.) 1 part and 3 parts of acetylene black (Denka Black HS-100, manufactured by Denki Kagaku Kogyo Co., Ltd.) were placed in a planetary mixer and stirred for 30 minutes, and then passed once through 3 rolls. After returning this to the planetary mixer, 50 parts of dimethylpolysiloxane B was further added, and stirring was continued for 30 minutes. Thereafter, 2.1 parts of methylhydrogenpolysiloxane having a Si—H group at both ends and side chains as a crosslinking agent (polymerization degree 17, Si—H amount 0.0060 mol / g), and ethynylcyclohexanol 0 as a reaction control agent 0.05 part and 0.1 part of platinum catalyst (Pt concentration 1%) were added and stirring was continued for 15 minutes to obtain a silicone rubber composition. The viscosity of this composition at room temperature (25 ° C.) was measured under the condition of 10 rpm using a BH viscometer and rotor No. 7, and the results are shown in Table 1.

  The results of measuring the rubber hardness, compression set, and volume resistivity from this silicone rubber composition in the same manner as in Example 1 are shown in Table 1. Further, the volume resistivity according to the production lot is also shown in Table 2.

[Comparative Example 2]
60 parts of dimethylpolysiloxane C (degree of polymerization 200) of Example 2, 2.3 parts of acetylene black (Denka Black HS-200, manufactured by Denki Kagaku Kogyo Co., Ltd.), white conductive titanium oxide ET-500W (Ishihara Sangyo Co., Ltd.) 5 parts) was put into a planetary mixer and stirred for 30 minutes, and then passed once through three rolls. Thereafter, the mixture was returned to the planetary mixer, 40 parts of dimethylpolysiloxane C was further added, and stirring was continued for 30 minutes. Thereafter, 3.6 parts of methylhydrogenpolysiloxane having a Si—H group only in the side chain as a crosslinking agent (polymerization degree 50, Si—H amount 0.0045 mol / g), and ethynylcyclohexanol 0.05 as a reaction control agent Part, platinum catalyst (Pt concentration 1%) 0.1 part was added and stirring was continued for 15 minutes to obtain a silicone rubber composition. The viscosity of this composition at room temperature (25 ° C.) was measured under the condition of 10 rpm using a BH viscometer and rotor No. 7, and the results are shown in Table 1.

  The results of measuring the rubber hardness, compression set, and volume resistivity from this silicone rubber composition in the same manner as in Example 1 are shown in Table 1. Further, the volume resistivity according to the production lot is also shown in Table 2.

Claims (6)

(A) Liquid organopolysiloxane having a polymerization degree of 800 or less and containing an alkenyl group bonded to at least two silicon atoms in one molecule: 97 to 70 parts by mass,
(B) Raw rubber-like organopolysiloxane having a polymerization degree of 2,000 or more and containing an alkenyl group bonded to at least two silicon atoms in one molecule: 3 to 30 parts by mass
(However, the total of the components (A) and (B) is 100 parts by mass.)
(C) Organohydrogenpolysiloxane containing hydrogen atoms bonded to at least two silicon atoms in one molecule: 0.1 to 30 parts by mass
(D) Carbon black: 0.5 to 50 parts by mass,
(E) Addition reaction catalyst: A conductive silicone rubber composition containing a catalytic amount and liquid at room temperature.   The conductive silicone rubber composition according to claim 1, wherein the viscosity at 25 ° C. is in the range of 30 to 600 Pa · s.   The conductive silicone rubber composition according to claim 1 or 2, wherein the volume resistivity of the cured silicone rubber is in the range of 10 MΩ · m to 10 Ω · m.   4. The conductive silicone rubber composition according to claim 1, which is used for a roll of an electrophotographic image forming apparatus.   The conductive silicone rubber composition according to claim 4, which is used for a developing roll of an electrophotographic image forming apparatus. The total amount of component (B), the total amount of component (D) and part of component (A) are mixed in advance, and then the remaining amount of component (A) and components (C) and (E) are added and further mixed. The method for producing a conductive silicone rubber composition according to claim 1.