JP2005113031A - Method of manufacturing conductive silicone rubber composition, and conductive silicone rubber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a liquid conductive silicone rubber composition from which a conductive silicone rubber having a dispersion of volume resistivity within a permissible range when it is cured can be obtained, the liquid conductive silicone rubber composition obtained by the method like this, and a conductive silicone rubber and a conductive roll obtained by curing the liquid conductive silicone rubber composition. <P>SOLUTION: The method of manufacturing the conductive silicone rubber composition includes a process (1) for preparing an admixture by kneading an alkenyl group-containing polyorganosiloxane (A) which has two or more alkenyl groups bonding to silicon atoms and of which the viscosity at 23 °C is 0.1 to 300 Pa s and a conductive carbon black (B) so that the degree of plasticity at 23 °C is 100 to 1,000, and a process (2) for blending the added (A) with it, and the method is characterised in that the liquid conductive silicone rubber having an apparent viscosity of 1 to 1,000 Pa s at 23 °C is prepared. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for producing a conductive silicone rubber composition, and more particularly to a method for producing a liquid conductive silicone rubber composition that cures by an addition reaction. The present invention also relates to a liquid conductive silicone rubber composition produced by the above method; and a conductive silicone rubber, a conductive roll and a conductive belt obtained by curing the composition.

  Silicone rubber is excellent in heat resistance, ultraviolet resistance, impact resilience, etc., has a low compression set, has a low hardness, and has excellent non-adhesiveness to toners. Widely used in various rolls such as printers and facsimiles, including fixing rolls, such as office equipment that is exposed to heat and ultraviolet rays and is used stably for a long period of time. In particular, an addition reaction curable silicone rubber composition cured by an addition reaction between an alkenyl group bonded to a silicon atom of a base polymer and a hydrosilyl group of a crosslinking agent is a liquid silicone rubber composition using a fluid base polymer. It is used in a wide range of applications because it has excellent dimensional stability without producing by-products during its processability and curing.

Conductive silicone rubber used for conductive rolls such as developing rolls is blended with conductive carbon black, conductive metal oxides, metal powders, etc. as conductive fillers. In addition, since the electric resistance can be arbitrarily adjusted according to the purpose, conductive carbon black powder has been used award. However, since carbon black has cohesive properties and is not sufficiently miscible with the system, the volume resistivity varies depending on the site, particularly in the region of 10 ³ to 10 ¹⁰ Ω · cm. Need to be stabilized.

  Patent Document 1 discloses a silicone rubber composition mainly comprising a millable type conductive silicone rubber and containing a polyorganosiloxane having 95 mol% or less of a methyl group in an organic group bonded to a silicon atom, and conductive carbon black. After preparing the product, the composition is further mixed with a separately prepared silicone rubber composition containing polyorganosiloxane having 98 mol% or more of methyl groups in the organic group bonded to the silicon atom. A production method for obtaining a composition that cures to form a silicone rubber exhibiting stable electrical resistance is disclosed. However, since the millable silicone rubber disclosed herein is inferior in productivity to liquid silicone rubber, it has been impossible to meet such demands when improvement in productivity is required.

  In Patent Document 2, a silicone rubber composition containing an alkenyl group-containing polyorganosiloxane, carbon black, and a curing agent is blended with an inorganic filler treated with a surfactant. When a surfactant is added to a silicone rubber composition containing a group-containing polyorganosiloxane, a conductive filler, and the necessary cross-linking agent and cross-linking catalyst, variation in volume resistivity occurs during curing. A conductive silicone rubber composition in which the above is suppressed is disclosed.

However, the method disclosed in Patent Document 2 is applied to a region having a volume resistivity of 10 ⁶ to 10 ¹⁰ Ω · cm in order to incorporate an inorganic filler such as wet silica treated with a surfactant. Even if it can, silicone rubber having higher conductivity cannot be obtained. Further, the variation in volume resistivity cannot be sufficiently suppressed, and the volume resistivity changes due to voltage fluctuation. On the other hand, in the method disclosed in Patent Document 3, a large amount of surfactant remains in the conductive silicone rubber obtained by curing. Since the surfactant contains a hydrophilic portion in the molecule, the resulting silicone rubber has drawbacks such as a large compression set. Therefore, the problem of obtaining a silicone rubber suitable for the manufacture of conductive parts such as conductive rolls with little variation in volume resistivity continues.
Japanese Patent Laid-Open No. 3-190964 JP-A-2-255769 Japanese Patent Laid-Open No. 10-030059

  An object of the present invention is to provide a method for producing a liquid conductive silicone rubber composition that can be cured to obtain a conductive silicone rubber having an acceptable volume resistivity variation, and a liquid conductive silicone obtained by such a method. It is to provide a rubber composition, a conductive silicone rubber obtained by curing the rubber composition, particularly a conductive roll and a conductive belt.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors formulated a part of the base polymer polyorganosiloxane and conductive carbon black so as to be in a specific plasticity range. After mixing, it was found that by blending the remaining base polymer, a silicone rubber composition capable of forming a conductive silicone rubber having an acceptable variation in volume resistivity was obtained, and the present invention was completed. It was.

That is, the present invention is a method for producing a conductive silicone rubber composition,
(1) (A) an alkenyl group-containing polyorganosiloxane having two or more alkenyl groups bonded to a silicon atom in one molecule and having a viscosity at 23 ° C. of 0.1 to 300 Pa · s; A step of preparing a blend by kneading a blend containing a functional carbon black so that the plasticity measured by the method defined in JIS K6249 at 23 ° C. is 100 to 1,000; and (2) Manufacturing comprising producing a liquid conductive silicone rubber composition having an apparent viscosity of 1 to 1,000 Pa · s at 23 ° C. by a method comprising a step of preparing a mixture by blending additional (A) Also relating to the method; a liquid conductive silicone rubber composition obtained by such a method, a conductive silicone rubber obtained by curing it, in particular a conductive roll and a conductive On the belt.

  In the step (1) in the present invention, the alkenyl group-containing polyorganosiloxane as the component (A) and the conductive carbon black as the component (B) are homogeneously mixed, and the plasticity at 23 ° C. is 100 to 1. 000 admixtures.

The alkenyl group-containing polyorganosiloxane (A) used in the present invention is a component that becomes a base polymer in the conductive silicone rubber composition of the present invention. This component (A) has two or more alkenyl groups bonded to a silicon atom in one molecule, and can form a network structure by addition reaction with the Si—H bond of component (C). Anything is acceptable. Typically, the general formula (I):
(R ¹ ) _a (R ² ) _b SiO _{(4-ab) / 2} (I)
(Where
R ¹ represents an alkenyl group;
R ² represents an unsubstituted or substituted monovalent hydrocarbon group that does not contain an aliphatic unsaturated carbon-carbon bond;
a is 1 or 2;
b is an integer of 0 to 2, provided that a + b is 2 or 3.
Is an alkenyl group-containing polyorganosiloxane having at least two alkenyl group-containing siloxane units in the molecule.

  The siloxane skeleton of component (A) may be linear or branched, and both may be used together. Since it is easy to control the synthesis and the average degree of polymerization, the component (A) is preferably linear, and when it is necessary to give excellent mechanical properties to the cured composition, the component (A) In the range of up to 20% by weight, it is more preferable to use a branched one in combination.

Examples of R ¹ include vinyl, allyl, 3-butenyl, 5-hexenyl, etc., which are easy to synthesize and do not impair the fluidity of the composition before curing and the heat resistance of the composition after curing. Therefore, a vinyl group is most preferable. a is preferably 1 because it is easy to synthesize.

Examples of the organic group bonded to the silicon atom of R ² and other siloxane units in the component (A) include alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, octyl, decyl, dodecyl; Cycloalkyl groups; aryl groups such as phenyl; aralkyl groups such as 2-phenylethyl and 2-phenylpropyl; substitutions such as chloromethyl, chlorophenyl, 3-cyanopropyl and 3,3,3-trifluoropropyl Examples are hydrocarbon groups. Of these, a methyl group is most preferred because it is easy to synthesize and has an excellent balance of properties such as mechanical strength and fluidity before curing.

R ¹ may be present at either the end or in the middle of the molecular chain of the polyorganosiloxane (A), or may be present at both of them, in order to give excellent mechanical properties to the composition after curing. Is preferably present at least at both ends thereof. The siloxane skeleton of the component (A) is substantially linear, but some branching may exist.

  The viscosity of the component (A) is such that the uncured composition exhibits good fluidity, exhibits excellent workability during casting and potting, and the cured composition exhibits excellent mechanical strength. In order to exhibit moderate elasticity and hardness, the viscosity at 23 ° C. is in the range of 0.1 to 500 Pa · s. This viscosity range is a typical (A) component, in the case of polymethylvinylsiloxane having both ends clogged with dimethylvinylsiloxane units and intermediate units consisting of dimethylsiloxy units, the number average degree of polymerization is 80-2. 000. The lower limit of the viscosity at 23 ° C. is preferably 0.2 Pa · s, and more preferably 0.3 Pa · s. The upper limit is preferably 300 Pa · s, more preferably 200 Pa · s. The component (A) may be used alone or in combination of two or more. In the latter case, the viscosity means the viscosity of the mixed alkenyl group-containing polyorganosiloxane. .

  Of the component (A), the amount used in step (1) is the same as the total amount of component (A) in order to uniformly disperse the component (B) in the system and suppress variation in volume resistivity of the silicone rubber. 20 to 50 weight% is preferable with respect to it.

The component (B) is a component for imparting conductivity to the silicone rubber obtained by curing the composition. As the component (B), oil furnace black, gas furnace black, acetylene black, etc. are exemplified depending on the required conductivity, and particularly if it exhibits a volume resistivity of 10 ⁵ Ω · cm or less. The present invention is not limited, and one type may be used alone or two or more types may be used in combination. For applications that require particularly high conductivity, it is preferable to use a highly conductive oil furnace black such as the Ketjen Black EC series (trade name of Ketjen). The amount of the component (B) is the total amount of the component (A) including the component (A) blended in the step (2) since the silicone rubber exhibits the necessary conductivity and exhibits excellent mechanical properties. On the other hand, the range of 0.05 to 20% by weight is preferable, and 0.1 to 15% by weight is more preferable.

  In the step (1), in addition to the components (A) and (B), fillers other than the component (B) described later may be blended to such an extent that the target volume resistivity can be secured. The plasticity of the mixture in this case is the plasticity of the system including the filler. The kneading in the step (1) is usually performed for 0.5 to 24 hours using a mixing device such as a kneader, a planetary mixer, or a universal kneader at room temperature to 200 ° C. until a homogeneous mixture is obtained. .

  The plasticity of the mixture prepared in step (1) is in the range of 100 to 1,000 at 23 ° C, preferably 100 to 500, and more preferably 120 to 300. If the plasticity is less than 100, the shear stress necessary to uniformly disperse the component (B) cannot be applied during the kneading, so that the component (B) cannot be homogeneously dispersed in the system and cured. Thus, it is impossible to give a volume resistivity with little variation depending on the part to the silicone rubber obtained. On the other hand, when the plasticity exceeds 1,000, the admixture is too hard and it is difficult to obtain a homogeneous mixture in step (2).

  Step (2) is a step of blending and mixing the remaining component (A) to obtain a mixture. The component (A) blended in the step (2) may be the same as or different from the component (A) used in the step (1). Moreover, also in a process (2), the filler other than the below-mentioned (B) component etc. can be mix | blended similarly to the process (1). The mixing in the step (2) is usually performed at room temperature to 200 ° C. for 0.5 to 24 hours using a mixing apparatus such as a kneader, a planetary mixer, or a universal kneader.

  (C) component and (D) component are mix | blended with the composition of this invention as a hardening | curing agent and hardening catalyst for hardening to silicone rubber.

In the polyorganohydrogensiloxane of component (C) used in the present invention, the hydrosilyl group contained in the molecule undergoes an addition reaction with R ^{1 in} component (A), thereby crosslinking the component (A). Although it functions as an agent, a part of it may function as a lengthening extender as described later. Among them, those functioning as a crosslinking agent have at least three hydrogen atoms bonded to silicon atoms involved in the addition reaction in the molecule in order to reticulate the cured product. In addition, depending on the purpose, in order to obtain good workability, while lowering the apparent particle size of the uncured composition, the hardness of the rubber after curing is lowered and the elongation is improved. As a part, a lengthening agent may be added. As the extension extender, those having two hydrogen atoms bonded to silicon atoms in the molecule are used, and such hydrogen atoms are bonded to silicon atoms at both ends of the linear component (C). It is preferable.

The component (C) is typically represented by the general formula (II):
(R ⁴ ) _c H _d SiO _{(4-cd) / 2} (II)
(Where
R ⁴ represents an unsubstituted or substituted monovalent hydrocarbon group that does not contain an aliphatic unsaturated carbon-carbon bond;
c is an integer from 0 to 2;
d is 1 or 2, provided that c + d is an integer of 1 to 3)
When the component (C) is composed of only a crosslinking agent, it has at least 3 units, and when it comprises a crosslinking agent and a lengthening extender, it has an average of more than 2 units in the molecule.

Examples of the organic group bonded to the silicon atom of R ⁴ and the other siloxane unit of component (C) are the same as those of R ^{2 in} component (A) described above, and among these, from the viewpoint of easy synthesis The methyl group is most preferred. Further, d is preferably 1 because synthesis is easy.

  The siloxane skeleton in the component (C) may be linear, branched or cyclic. Moreover, you may use these mixtures.

  The degree of polymerization of the component (C) is not particularly limited, but since polyorganohydrogensiloxane in which two or more hydrogen atoms are bonded to the same silicon atom is difficult to synthesize, it is preferably composed of three or more siloxane units. The number of siloxane units is more preferably 6 to 200, and particularly preferably 10 to 150, since it does not exhibit even when heated to the curing temperature and is excellent in fluidity and easily mixed with the component (A).

The amount of component (C) is completely cured and the silicone rubber obtained by curing has excellent mechanical properties. Therefore, silicon in component (C) relative to R ¹ group in component (A) The amount is such that the ratio of hydrogen atoms bonded to the atoms (H / Vi) is 0.5 to 10.0, preferably 1.0 to 5.0. If H / Vi is less than 0.5, a silicone rubber having excellent mechanical strength cannot be obtained. If it exceeds 10.0, foaming may occur during curing, and an excellent silicone rubber can also be obtained. Can not.

  The platinum-based catalyst of component (D) used in the present invention is a catalyst for promoting the addition reaction between the alkenyl group in component (A) and the hydrosilyl group in component (C).

  As the platinum group metal compound, a compound of a platinum group metal atom such as platinum, rhodium, palladium is used, and chloroplatinic acid, a reaction product of chloroplatinic acid and an alcohol, a platinum-olefin complex, a platinum-vinylsiloxane complex, Examples include platinum compounds such as platinum-ketone complexes and platinum-phosphine complexes; rhodium compounds such as rhodium-phosphine complexes and rhodium-sulfide complexes; palladium compounds such as palladium-phosphine complexes.

  Of these, a reaction product of chloroplatinic acid and an alcohol and a platinum-vinylsiloxane complex are preferable from the viewpoint of good catalytic activity. In order to uniformly disperse the complex in the system, the complex is converted into the component (A). Such alkenyl group-containing polyorganosiloxanes, particularly those dispersed in linear or cyclic polymethylvinylsiloxane may be used.

  The blending amount of component (D) is usually 0.1 to 1,000 weight in terms of platinum group metal atom, based on the total amount of component (A) and component (C), because an excellent curing rate is obtained. ppm, preferably 0.5 to 200 ppm by weight.

  In order to improve the storage stability of the composition or the workability of molding / curing, the composition of the present invention may contain a curing inhibitor as necessary. As a curing inhibitor, acetylene alcohols such as 3-methyl-1-butyn-3-ol, 3,5-dimethyl-1-hexyn-3-ol, and 3-phenyl-1-butyn-3-ol; Ene-yne compounds such as 3-methyl-3-penten-1-yne and 3,5-dimethyl-3-hexen-1-yne; 1,3,5,7-tetramethyl-1,3,5, Alkenyl group-containing cyclic siloxane compounds such as 7-tetravinylcyclotetrasiloxane and 1,3,5,7-tetramethyl-1,3,5,7-tetrahexenylcyclotetrasiloxane; triazoles such as benzotriazole; Examples include phosphines; mercaptans; hydrazines. As for the compounding quantity of a hardening inhibitor, 0.001-5 weight part is preferable with respect to 100 weight part of (A) component. In order to obtain more stable conductivity, for example, the time to reach a curing rate of 10% at 130 ° C. is 30 to 300 seconds for the types and amounts of the component (C), the component (D) and the curing inhibitor. It is preferable to select as follows.

  The blending of the component (C) and the component (D) can be performed in any step such as the step (1), the step (2), the step provided between them, and the step after the step (2). . However, component (C) and component (D) are blended in separate steps unless special measures such as blending a curing inhibitor are taken in order to make the composition stably exist in an uncured state. It is preferable to do.

  In order to give the composition of the present invention appropriate fluidity at the stage before curing, and to give the rubber-like elastic body obtained by curing high mechanical strength required according to its use, (B ) In addition to the component, an inorganic filler may be blended. As the inorganic filler, those having an average particle size of 0.1 to 50 μm are preferable. Such inorganic fillers include diatomaceous earth, ground quartz, fused quartz, titanium oxide, aluminum oxide, zinc oxide, aluminosilicate, calcium carbonate, organic acid surface treated calcium carbonate, magnesium carbonate, zinc carbonate, calcium silicate. , Talc, ferric oxide and the like are exemplified, and are selected according to extrusion workability and physical properties required for the silicone rubber obtained by curing. Moreover, you may mix | blend nonelectroconductive carbon black according to the objective. The addition amount of these fillers is usually 100 parts by weight or less with respect to 100 parts by weight of component (A). Further, depending on the case, a reinforcing filler having an average particle diameter of 3 to 100 nm, such as fumed silica, precipitated silica, and fumed titanium oxide, may be blended.

  Further, the composition of the present invention includes a pigment, a thixotropy imparting agent, a viscosity modifier for improving extrusion workability, an ultraviolet light inhibitor, a fungicide, a heat resistance improver, a flame retardant, depending on the purpose. Various additives such as an agent, an adhesion improver, and a curing inhibitor may be added. Depending on the application, the composition of the present invention may be dissolved or dispersed in an organic solvent such as toluene or xylene.

  These fillers and additives that are optionally blended may be blended in any step, such as step (1), step (2), step provided between them, step after step (2), etc. be able to.

  As described above, the conductive silicone rubber composition is prepared to have an apparent viscosity of 1 to 1,000 Pa · s, preferably 50 to 300 Pa · s at 23 ° C., by the method including the steps (1) and (2). The If the apparent viscosity is less than 1 Pa · s, the filler may settle, and if it exceeds 1,000 Pa · s, it is difficult to handle.

  The conductive silicone rubber composition of the present invention is molded by a molding method such as compression molding, injection molding or transfer molding using a mold; Silicone rubber molded articles, coated articles, sheets and the like can be obtained. In the cross-linking reaction, molding is performed by heating at a temperature of 80 to 180 ° C. for 5 minutes to several hours, for example, depending on the type and amount of the component (D) used and the presence or absence and type and amount of the curing inhibitor. Furthermore, you may heat-process, for example in 150-250 degreeC as needed. Although not particularly limited, it is preferable to perform heat treatment at 150 to 200 ° C. for 1 to 6 hours. In order to reduce the variation in volume resistivity after curing, it is preferable to perform the molding at a temperature of 100 to 150 ° C.

The method for producing the conductive roll from the conductive silicone rubber composition of the present invention is not particularly limited. For example, the conductive silicone rubber composition is wound by injection molding on a core that has been previously surface-treated with a primer. A coating layer may be formed on the cored bar by any method, and then heated to form a cured silicone rubber layer. In this case, in order to particularly reduce the variation in volume resistivity after curing, the molding is preferably performed at a pressure of 1 to 10 MPa {10.2 to 102 kgf / cm ² }, and the pressure of 1 to 5 MPa {10.2 to 51 kgf. / cm ² } is more preferable. Further, if necessary, an outer layer such as NBR, urethane rubber, hydrin rubber, fluororubber, or fluororesin may be formed on the outer periphery of the silicone rubber layer.

By using the production method of the present invention, the conductive silicone rubber composition of the present invention can uniformly disperse the conductive carbon black in the system. Therefore, the conductive silicone rubber composition can be cured to have an arbitrary value of 10 ³ to 10 ¹⁰ Ω · cm. Silicone rubber having conductivity and small variation in volume resistivity depending on the part can be formed. Therefore, the conductive silicone rubber and the conductive roll of the present invention have little variation in volume resistivity depending on the part.

  Hereinafter, the present invention will be described in more detail by way of examples. In these examples, parts indicate parts by weight, and the viscosity indicates the viscosity at 23 ° C. The present invention is not limited by these examples.

In Examples and Comparative Examples, the following polysiloxanes were used as the components (A) and (C). Hereinafter, siloxane units are indicated by the following symbols.
M Unit: (CH ₃ ) ₃ SiO _1/2 −
M ^v unit: (CH ₃ ) ₂ (CH ₂ ═CH) SiO _1/2 −
D Unit: - (CH _{3) 2} SiO-
D ^H units: - (CH ₃₎ HSiO-
D ^v _{Unit: - (CH 3) (CH} 2 = CH) SiO-
A-1: both terminals blocked with M ^v basis, will intermediate units from D units, linear polymethyl vinyl siloxane viscosity is 3 Pa · s;
C-1: A linear polymethylhydrogensiloxane having both ends blocked with M units, an intermediate unit consisting of 50 mol% ^DH units and the remaining D units, and a viscosity of 20 mPa · s.

In the examples and comparative examples, the following conductive carbon black was used as the component (B).
B-1: Denka Black (trade name of Electrochemical Co., Ltd.)
B-2: Ketjen Black EC (trade name of Ketjen)

In the examples and comparative examples, the following platinum complexes were used as the component (D).
D-1: A complex obtained by heating chloroplatinic acid with a cyclic siloxane tetramer represented by D ^v ₄ and having a platinum content of 2% by weight.

  First, as step (1), 100 parts of A-1 was added to a planetary mixer, 34 parts of B-1 was added, and kneaded at room temperature for 3 hours until a uniform mixture was obtained. The plasticity of the blend thus prepared was 200. Next, as a process (2), 100 parts of A-1 was added to this mixture in the planetary mixer, and it stirred and mixed at room temperature until it became uniform. The apparent viscosity of the system at this stage was 150 Pa · s. Furthermore, by mixing and mixing 4.0 parts of C-1 and then mixing 0.1 parts of 3-methyl-1-butyn-3-ol and 0.1 parts of D-1 and mixing. A conductive silicone rubber composition was prepared.

The time (t ₁₀ ) at which the torque reaches a value corresponding to 10% of the torque of a completely cured product at 130 ° C. in a curing test of the composition using a curast meter V type (trade name of JSR Corporation) is 60. Second. On the other hand, this composition was cast into a mold, pressurized to 3 MPa {30.6 kgf / cm ² }, and cured by heating at 130 ° C. for 10 minutes to produce a test piece of 150 × 150 mm and thickness 1 mm. did. About this test piece, the volume resistivity of five places per sample was measured by the method of JIS K6249. As a result, the average value is 5x10 ³ Ω · cm, the lower limit is 1x10 ³ Ω · cm, the upper limit was 9x10 ³ Ω · cm.

The amount of B-1 to be blended in step (1) is 23 parts, the amount of A-1 to be replenished in step (2) is 35 parts, and the blending ratio of B-1 to the whole A-1 is Example 1. Accordingly, other components were blended in the same blending ratio, and a conductive silicone rubber composition was prepared in the same procedure as in Example 1. And used to measure the t ₁₀ of the composition. Furthermore, a test piece was prepared in the same manner as in Example 1 except that the molding pressure was 6 MPa {61.2 kgf / cm ² }, and the volume resistivity of the cured product was measured. The results are shown in Table 1.

Comparative Examples 1 and 2
Comparative Example 1 in which a conductive silicone rubber composition was prepared in the same manner as in Example 1 except that the whole amount of A-1 was blended in the step (1) and the step (2) was not performed according to the above blending ratio; And, by reducing the blending amount of B-1 in step (1), an admixture having a plasticity of 80 was prepared, and the conductive silicone rubber composition was prepared in the same manner as in Example 1 except that it was used in the following steps. Test pieces were prepared in the same manner from the prepared Comparative Example 2, and the volume resistivity was measured.

The amount of each component of Examples 1 and 2; plasticity of the resulting admixture in step (1), the apparent viscosity of the mixture obtained in step (2); t ₁₀ and the molding pressure And the distribution of volume resistivity of the obtained cured product was as shown in Table 1.

  A conductive silicone rubber composition was prepared in the same procedure as in Example 1 except that 30 parts of pulverized quartz was further added in the step (1). Using this, a test piece was prepared in the same manner as in Example 1, and the volume resistivity was measured. The results were as shown in Table 2.

  After adding 15 parts of B-2 instead of B-1 in Step (1), adding 400 parts of A-1 in Step (2), and adding A-1 in Step (2) A conductive silicone rubber composition was prepared in the same manner as in Example 1 except that the mixture was heated to 150 ° C. Using this, a test piece was prepared in the same manner as in Example 1, and the volume resistivity was measured. The results were as shown in Table 2.

Comparative Example 3
A conductive silicone rubber composition was prepared in the same procedure as in Comparative Example 1, except that 15 parts of pulverized quartz was further added in the step (1). Using this, a test piece was prepared in the same manner as in Comparative Example 1, and the volume resistivity was measured. The results were as shown in Table 2.

Comparative Example 4
In step (1), except that the amount of A-1 was increased to 500 parts, kneading was performed at room temperature in the same manner as in Comparative Example 1, but B-2 was not uniformly dispersed in A-1, It was impossible to measure the plasticity of the mixture. Since a homogeneous mixture could not be obtained, the subsequent steps were terminated.

  As is apparent from Tables 1 and 2, the conductive silicone rubber composition prepared through the step of obtaining an admixture having a plasticity of 100 to 1,000 according to the present invention has little variation due to the volume resistivity site, A conductive silicone rubber having stable conductivity was provided. On the other hand, the conductive silicone rubber obtained from the composition of the comparative example prepared without using the above-mentioned step of obtaining the blend or through the blend having a plasticity of the blend of less than 100 is There were many variations in sex.

  The conductive silicone rubber composition produced by the production method of the present invention is useful for producing various conductive silicone rubber molded articles, particularly conductive rolls having a conductive silicone rubber layer, by curing.

  The conductive silicone rubber of the present invention is useful for belts such as a fixing belt, a charging belt, a transfer belt, and a cleaning belt, and automobile parts. In particular, the conductive roll of the present invention is used in various electronic devices such as dry copying machines, such as a charging roll, a transfer roll, a developing roll, a paper feed roll, a fixing roll, a pressure roll, an antistatic roll, a cleaning roll, and a coating roll. It is used for a wide range of applications.

Claims (6)

A method for producing a conductive silicone rubber composition, comprising:
(1) (A) an alkenyl group-containing polyorganosiloxane having two or more alkenyl groups bonded to a silicon atom in one molecule and having a viscosity at 23 ° C. of 0.1 to 300 Pa · s; A step of preparing a blend by kneading a blend containing a functional carbon black so that the plasticity measured by a method defined in JIS K6249 at 23 ° C. is 100 to 1,000; and (2) Manufacturing comprising producing a liquid conductive silicone rubber composition having an apparent viscosity of 1 to 1,000 Pa · s at 23 ° C. by a method comprising a step of preparing a mixture by blending additional (A) Method.   Furthermore, (C) a polyorganohydrogensiloxane having 3 or more hydrogen atoms bonded to a silicon atom, and the number of hydrogen atoms bonded to a silicon atom with respect to one alkenyl group in the component (A) In an amount of 0.5 to 10; and (D) a platinum group metal compound, and an amount of 0.1 to 1,000 ppm by weight based on the amount of (A). The manufacturing method according to claim 1.   A liquid conductive silicone rubber composition produced by the production method according to claim 1 or 2.   A conductive silicone rubber obtained by curing the liquid conductive silicone rubber composition according to claim 3.   A conductive roll obtained by winding and curing the liquid conductive silicone rubber composition according to claim 3 around a cored bar.   A conductive belt using the conductive silicone rubber according to claim 4.