JP2002012766A - Silicone rubber composition, silicon rubber molded article and manufacturing method of silicone rubber molded article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a silicone rubber composition which can be uniformly mixed for a short time and gives a homogeneous silicone rubber molded article after cured. SOLUTION: The silicone rubber composition is obtained by admixing (A) a silicone rubber base compound which comprises (a) an organopolysiloxane raw rubber having a Williams plasticity at 25 deg.C of at least 50 and bearing at least two alkenyl groups bonded to silicon in one molecule, (b) an inorganic filler and (c) a platinum-based catalyst (a catalytic amount) and has a Williams plasticity at 25 deg.C within the range of 100-1,000 with (B) a silicone rubber base compound which comprises (a) an organopolysiloxane raw rubber having a Williams plasticity of at least 50 and bearing at least two alkenyl groups bonded to silicon in one molecule, (b) an inorganic filler and (d) an organohydrogen polysiloxane bearing at least two hydrogen atoms bonded to silicon in one molecule and has a Williams plasticity at 25 deg.C within the range of 100-1,000.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silicone rubber composition, a silicone rubber molded product, and a method for producing a silicone rubber molded product. The present invention relates to a silicone rubber composition which can be a homogeneous molded article, a silicone rubber molded article, and a method for producing a silicone rubber molded article.

[0002]

2. Description of the Related Art Vinyl-containing organopolysiloxanes,
Silicone rubber compositions (addition reaction-curable silicone rubber compositions) containing inorganic fillers and organohydrogenpolysiloxanes containing silicon-bonded hydrogen atoms as main components and curing in the presence of a platinum-based catalyst give off-odors during curing. It does not emit or generate reaction by-products. However, this kind of addition-curable silicone rubber composition has a problem that storage stability is poor and usable time is short. For that purpose, the conventional addition-curable silicone rubber composition stores the components constituting the components separately, and mixes these components to produce a silicone rubber composition when producing a silicone rubber molded article. A method has been adopted in which this is directly introduced into a molding machine and cured under heating to produce a silicone rubber molded product. However, the components constituting this type of silicone rubber composition do not have an affinity for each other, and it has been necessary to mix them over a long period of time to uniformly mix them. Therefore, during this mixing, the curing of the silicone rubber composition starts to progress, or the catalytic activity of the platinum-based catalyst decreases,
The physical properties of the finally obtained silicone rubber molded article sometimes varied. Such a problem is not so much regarded as an organopolysilon composition based on a liquid organopolysiloxane, but has a high plasticity and a composition based on a high-molecular-weight organopolysiloxane raw rubber. Was a major problem.

[0003]

The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, have found that the components constituting the addition-reaction-curable silicone rubber composition are two types of silicones having a specific plasticity. The above problem can be solved by dividing and storing a rubber-based compound to prepare a silicone rubber molded article, and mixing these two types of silicone rubber-based compound to form a silicone rubber composition. And completed the present invention. That is, an object of the present invention is to provide a silicone rubber composition, a silicone rubber molded product, and a method for producing the silicone rubber molded product, which can be uniformly mixed in a short time and can be formed into a homogeneous silicone rubber molded product after heat curing. Is to provide.

[0004]

The object of the present invention is to provide a compound of the formula (A) (a) wherein R is a monovalent hydrocarbon group or a halogenated alkyl group, wherein R _a SiO _{(4-a) / 2} ; Yes, a is 1.8 ~
2.3 number. ), Having a Williams plasticity of 50 or more at 25 ° C. and containing two or more silicon-containing alkenyl groups per molecule (100 parts by weight), (b) an inorganic filler (1 to 4
00 parts by weight), (C) a platinum-based catalyst (catalytic amount),
Williams plasticity at 25 ° C of 50 to 1,000
A silicone rubber-based compound in the range of
(B) (a) Average unit formula: R _a SiO _{(4-a) / 2} (where R is a monovalent hydrocarbon group or a halogenated alkyl group,
a is a number from 1.8 to 2.3. ), An organopolysiloxane raw rubber (100 parts by weight) having a Williams plasticity of 50 or more and containing two or more silicon alkenyls in one molecule, (b) an inorganic filler (1 to 40)
0 parts by weight), (d) an organohydrogenpolysiloxane (0.1 to 10 parts by weight) containing two or more silicon-bonded hydrogen atoms in one molecule, and having a Williams plasticity of 100 to 1 at 25 ° C. A silicone rubber composition characterized by being mixed with a silicone rubber base compound in the range of 3,000. "A silicone rubber molded product obtained by heating and curing the silicone rubber composition, and" the following components (A) and (B) are separately produced and stored, and when producing a silicone rubber molded product, The component (A) and the component (B) are introduced into a mixing device and mixed to form a silicone rubber composition. Thereafter, the composition is supplied into a silicone rubber molding device and cured by heating. (A) (a) Average unit formula: R _a SiO _{(4-a) / 2} (wherein R
Is a monovalent hydrocarbon group or a halogenated alkyl group, and a is a number from 1.8 to 2.3. ) And 25
C. has a Williams plasticity of 50 or more, and contains two or more alkenyl silicon-containing organopolysiloxanes in one molecule (100 parts by weight), (b) an inorganic filler (1 to 400 parts by weight), ( C) A silicone rubber-based compound comprising a platinum-based catalyst (catalytic amount) and having a Williams plasticity at 25 ° C. in the range of 50 to 1,000. (B) (a) Average unit formula: R _a SiO
_{(4-a) / 2} (wherein R is a monovalent hydrocarbon group or a halogenated alkyl group, and a is a number from 1.8 to 2.3), and has a Williams plasticity of 50. The above is an organopolysiloxane raw rubber containing two or more silicon alkenyl in one molecule (100 parts by weight),
(B) an inorganic filler (1 to 400 parts by weight), (d) an organohydrogenpolysiloxane containing two or more silicon-bonded hydrogen atoms in one molecule (0.1 to 10 parts by weight), Williams plasticity at ℃ 1
A silicone rubber-based compound in the range of from 1,000 to 1,000. Is achieved.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
Organopolysiloxa of component (a) that constitutes component (A)
Raw rubber has an average unit formula: R_aSiO_{(4-a) / 2}(Where R
Is a monovalent hydrocarbon group or a halogenated alkyl group.
Monovalent hydrocarbon groups include methyl, ethyl,
Alkyl groups such as pill groups; vinyl groups, allyl groups, hexeni
Alkenyl groups such as phenyl group; ants such as phenyl group and tolyl group
And a halogenated alkyl group of 3,
3,3-trifluoropropyl group and chloropropyl group
Is exemplified. a is a number from 1.8 to 2.3. )
Containing two or more silicon-bonded alkenyl groups in one molecule
It is necessary to. And this organopolysilo
Xan raw rubber has a Williams plasticity at 25 ° C.
Must be at least 50 and must be at least 100
Is preferred. Here, William plasticity is JIS K
6249: 1997 "Uncured and cured silicone rubbers
According to the plasticity test specified in the
Polysiloxane raw rubber volume 2cm^Three Cylindrical specimen
This test piece is sandwiched between cellophane paper and
Parallel plate plasticity meter with dimple (Ueshima Seisakusho; William
Splastometer) and apply a load of 49N
And let it stand for 2 minutes.
And record the thickness of the specimen,
Was multiplied by 100 to obtain plasticity. Also, its weight average molecule
25 × 10^FourIt is preferable that it is above. like this
As the organopolysiloxane, trimethylsiloxane at both ends is used.
Roxy-blocked methylvinylpolysiloxane raw rubber, both ends
Trimethylsiloxy end-blocked dimethylsiloxane methyl
Vinyl siloxane copolymer raw rubber,
Nylsiloxy group-blocked dimethylpolysiloxane raw rubber, both
Dimethylsiloxane with terminal dimethylvinylsiloxy group
・ Methylvinylsiloxane copolymer rubber, both ends
Dimethyl siloxane
Tylvinylsiloxane copolymer raw rubber, both ends methyl
Nylhydroxysiloxy group-blocked dimethylsiloxane
Cylvinylsiloxane / methylphenylsiloxane
Combined raw rubber, methylvinylhydroxysiloxy groups at both ends
Blocked dimethyl siloxane, methyl vinyl siloxane,
(3,3,3-trifluoropropyl) methylsiloxane
Copolymer raw rubber is exemplified.

As the inorganic filler of the component (b), finely divided silica such as dry silica and wet silica and the like, and their surfaces are composed of organochlorosilane, hexaorganodisilazane, organopolysiloxane, diorganocyclopolysiloxane and the like. Fillers such as finely powdered silica hydrophobized with an organosilicon compound of the following; quasi-reinforcing fillers such as quartz powder, diatomaceous earth, calcium carbonate, carbon black or bulking fillers; iron oxides, rare earths Heat-resistant agents such as compounds; flame retardants such as manganese carbonate, titanium oxide, aluminum oxide, aluminum hydroxide, and zinc oxide; and pigments. If the compounding amount of this component is too large, it is difficult to mix the component (a) with the component (a).
1 to 400 parts by weight, preferably 5 parts by weight
２００200 parts by weight.

The platinum-based catalyst of the component (c) promotes the addition reaction between the alkenyl group in the component (a) and the silicon-bonded hydrogen atom in the component (d) described below to cure the composition of the present invention. Catalyst. Such a component (c) includes platinum powder, platinum black, chloroplatinic acid, alcohol-modified chloroplatinic acid, a complex of platinum and diketone, a complex of chloroplatinic acid and olefins, a complex of chloroplatinic acid and alkenylsiloxane,
And those in which these are carried on a carrier such as alumina, silica and carbon black. Among these, a complex of chloroplatinic acid and alkenylsiloxane is preferred because of its high catalytic activity as a hydrosilylation reaction catalyst. Particularly, chloroplatinic acid and 1,3-divinyltetrachloride as disclosed in JP-B-42-22924 are preferred. Methyldisiloxane complexes are preferred. Further, a catalyst in which the platinum-based catalyst is microencapsulated with a thermoplastic resin to improve the storage stability, as proposed in Japanese Patent Publication No. 5-58458, can also be used. The addition amount of this component is 0.1 to 1000 parts by weight, preferably 1 to 100 parts by weight, as platinum metal atoms, based on 1,000,000 parts by weight of component (a).

The component (A) is easily produced by uniformly mixing the components (a), (b) and (c), but generally, the components (a) and (b) Is uniformly mixed to produce a silicone rubber base, and then the component (c) is added to and blended with the silicone rubber base. As the production apparatus, an apparatus conventionally used for producing silicone rubber, such as a kneader mixer, a continuous kneading extruder, or a two-roll machine, can be applied.

The component (A) and the component (b) constituting the component (B)
Examples of the component include those similar to those described in the section on the description of the component (A).

The organohydrogenpolysiloxane of the component (d) constituting the component (B) is a cross-linking agent for the organopolysiloxane raw rubber of the component (a), and the silicone rubber composition forms a network structure to form a rubber. It is necessary to have two or more silicon-bonded hydrogen atoms in one molecule in order to have the characteristics described above. Organic groups other than hydrogen atoms bonded to silicon atoms include methyl groups,
Examples include alkyl groups such as ethyl group and propyl group; alkenyl groups such as vinyl group, allyl group and hexenyl group; and aryl groups such as phenyl group and tolyl group. The molecular structure of this component may be any of a linear structure, a branched chain structure, a network structure, a cyclic structure, and a three-dimensional structure. The viscosity of the organohydrogenpolysiloxane at 25 ° C. is generally 0.5 to 50,000 centipoise, preferably 1 to 10,000 centipoise. The amount of this component is in the range of 0.1 to 10 parts by weight per 100 parts by weight of component (a).

The component (B) is easily produced by uniformly mixing the components (a), (b) and (d), but generally, the components (a) and (b) Is uniformly mixed to produce a silicone rubber base, and then the component (d) is added to the silicone rubber base and blended. As the production apparatus, an apparatus conventionally used for producing silicone rubber, such as a kneader mixer, a continuous kneading extruder, or a two-roll machine, can be applied.

The composition of the present invention is a mixture of the above-mentioned components (A) and (B). In addition to these components, it is known to be added to a silicone rubber composition. The addition and blending of the various additives may be performed as long as the object of the present invention is not impaired. Such additives include diorganopolysiloxanes having silanol groups at both ends, crepe hardening inhibitors such as silanol group-containing organosilanes, hexaorganodisilazane, storage stability and curing properties of benzotriazole and acetylene compounds. And heat-resistant agents such as cerium silanolate and cerium fatty acid salts; and mold release agents such as stearic acid, zinc stearate, calcium stearate and the like.

The composition of the present invention is obtained by mixing the components (A) and (B) as described above. The Williams plasticity of the component (A) at 25 ° C. and the component (B)
C., the ratio of Williams plasticity is (1.0:
0.8) to (1.0: 1.2). Further, the mixing ratio of the component (A) and the component (B) is preferably in a range of (1: 0.9) to (1: 1.1) by weight ratio, and (1.0: 1.0). ) Is more preferable.

In order to produce a silicone rubber molded article using the composition of the present invention, the above components (A) and (B) are produced separately and stored separately, and the silicone rubber molded article is produced. In doing so, the components (A) and (B) are introduced into a mixing device and mixed to form a silicone rubber composition. Thereafter, the composition is supplied into a silicone rubber molding device and cured by heating. In this case, the mixing device is preferably a roll mill such as a two-roll mill or a kneader mixer. As the molding apparatus, conventionally known injection molding machines, extrusion molding machines, and compression molding machines can be applied.

The composition of the present invention as described above allows the components (A) and (B) to be uniformly mixed in a short time, has a long pot life, and has a uniform silicone rubber molded article after heat curing. Therefore, it is extremely useful as a silicone rubber composition required for such properties, for example, a silicone rubber composition for extrusion applied to tubes, sheets, wire covering materials and the like.

[0016]

Next, the present invention will be described with reference to examples. In Examples, “parts” means “parts by weight”. In the examples, William plasticity and viscosity are measured values at 25 ° C. Here, the William's plasticity was measured as follows. ○ William plasticity: JIS K6249: 1997
It measured according to the plasticity test prescribed | regulated to "Test method of uncured and cured silicone rubber." That is, the organopolysiloxane raw rubber was used as a cylindrical test piece having a volume of 2 cm ³ . Next, the test piece was sandwiched between cellophane papers and set in a parallel plate plasticity meter (William Plastometer manufactured by Ueshima Seisakusho) equipped with a dial gauge. Read the scale to millimeter, record the thickness of the specimen,
This value was multiplied by 100 to obtain the plasticity. ○ Evaluation method of miscibility The silicone rubber base compound of the component (A) and the silicone rubber base compound of the component (B)
It was put on this roll and mixed at a temperature of 23 ° C. under constant conditions (front roll rotation speed 33 rpm, back roll rotation speed 25 rpm, roll gap 2.5 mm) until uniform. Here, the time until it becomes uniform was measured as follows. That is, the silicone rubber base compound (silicone rubber composition) after mixing for a predetermined time is dispensed as a sheet from the two rolls, and three parts at the front, three at the center, and three at the rear of the dispensed sheet are tested. The test pieces were cut out and cured by heating at 170 ° C. for 10 minutes, and their hardness and tensile strength were measured. Then, these measurement data are within a certain error range (±
(Within a range of 5%), it was determined that they were uniformly mixed.

[0017]

Example 1 100 parts by weight of dimethylvinylsiloxy group-capped organopolysiloxane rubber (Williams plasticity: 160, weight average molecular weight: 500,000) consisting of 99.6 mol% of dimethylsiloxane units and 0.4 mol% of methylvinylsiloxane units Parts, viscosity at 25 ° C. is 60
3.5 parts of a dimethylsiloxane oligomer having a silanol group at both ends capped at mPa · s and 40 parts of dry process silica having a specific surface area of 200 m ² / g were charged into a kneader mixer, and heated (1).
(70 ° C.) until a uniform mixture was obtained to obtain a silicone rubber base. After cooling the silicone rubber base to 23 ° C., 70 ppm of the complex of chloroplatinic acid and divinyltetramethyldisiloxane was added as a platinum atom to 70 parts of the silicone rubber base at 2.3 ppm with respect to 1 million parts of the organopolysiloxane raw rubber. Weight) and uniformly mixed at 23 ° C. on a two-roll mill to produce a silicone rubber-based compound A. The Williams plasticity of this silicone rubber-based compound A was 180. Subsequently, the silicone rubber base 70 obtained above
In the part, the average molecular formula is Me ₃ SiO (Me ₂ SiO) ₃ (M
eHSiO) ₅ SiMe ₃ (wherein Me represents a methyl group) 0.45 parts of a dimethylsiloxane / methylhydrogensiloxane copolymer (viscosity 25 mpa · s) capped at both ends with a trimethylsiloxy group, a hydrosilylation reaction 0.0025 parts of 1-ethynyl-1-cyclohexanol as an inhibitor was added and uniformly mixed on a two-roll mill at 23 ° C. to produce a silicone rubber-based compound B. This silicone rubber-based compound B had a Williams plasticity of 180. Next, the silicone rubber-based compound A (100
Part) and silicone rubber-based compound B (100
Was mixed at 23 ° C. on a two-roll mill, and the mixing property was measured. Table 1 shows the results of these measurements.

[0018]

Comparative Example 1 Both ends dimethylvinylsiloxy group-blocked organopolysiloxane raw rubber composed of 99.6 mol% of dimethylsiloxane units and 0.4 mol% of methylvinylsiloxane units (Williams plasticity: 160, weight average molecular weight: 500,000) 100 Parts, viscosity at 25 ° C. is 60
3.5 parts of a dimethylsiloxane oligomer capped with silanol groups at both ends of mPa · s and 40 parts of dry-processed silica having a specific surface area of 200 m ² / g were charged into a kneader mixer and heated.
(170 ° C.) and kneaded until uniform to obtain a silicone rubber base. After the silicone rubber base was cooled to 23 ° C., 140 parts of the silicone rubber base had an average molecular formula of Me ₃ SiO (Me ₂ SiO) ₃ (MeHSiO) ₅ Si
0.9 part of a dimethylsiloxane / methylhydrogensiloxane copolymer (viscosity: 25 mPa · s) represented by Me ₃ (wherein, Me represents a methyl group), and 1-ethynyl-1-cyclohexane as a hydrosilylation reaction inhibitor. 0.005 part of hexanol, complex of chloroplatinic acid and 1,3 divinyltetramethyldisiloxane. 4.6 ppm as platinum atom based on 1 million parts of organopolysiloxane raw rubber.
(Weight) was added and mixed on a two-roll mill at 23 ° C., and the mixing property was measured. These measurement results are also shown in Table 1 below.

[0019]

Example 2 100 parts by weight of dimethylvinylsiloxy group-capped organopolysiloxane rubber (Williams plasticity: 160, weight average molecular weight: 500,000) consisting of 99.6 mol% of dimethylsiloxane units and 0.4 mol% of methylvinylsiloxane units Parts, viscosity at 25 ° C. is 60
3.5 parts of a dimethylsiloxane oligomer having a silanol group at both ends capped at mPa · s and 40 parts of dry process silica having a specific surface area of 200 m ² / g were charged into a kneader mixer, and heated (1).
(70 ° C.) until a uniform mixture was obtained to obtain a silicone rubber base. After the silicone rubber base was cooled to 23 ° C., 70 ppm of the complex of chloroplatinic acid and divinyltetramethyldisiloxane was added to 70 parts of the silicone rubber base as 2.3 ppm of platinum atom based on 1 million parts of organopolysiloxane raw rubber. Weight) and uniformly mixed at 23 ° C. on a two-roll mill to produce a silicone rubber-based compound A. The Williams plasticity of this silicone rubber-based compound A was 180. Subsequently, the silicone rubber base 70 obtained above
In the part, the average molecular formula is Me ₃ SiO (Me ₂ SiO) ₃ (M
eHSiO) ₅ SiMe ₃ (wherein Me represents a methyl group) 0.45 parts of a dimethylsiloxane / methylhydrogensiloxane copolymer (viscosity: 25 mps · s) capped with a trimethylsiloxy group at both terminals and a hydrosilylation reaction 0.0025 parts of 1-ethynyl-1-cyclohexanol as an inhibitor was added and uniformly mixed on a two-roll mill at 23 ° C. to produce a silicone rubber-based compound B. The Williams plasticity of this silicone rubber-based compound A was 180. Next, the silicone rubber-based compound A (100
Part) and silicone rubber-based compound B (100
Was mixed on a two-roll mill at 23 ° C. for 3 minutes to produce a silicone rubber composition. Next, this silicone rubber composition was introduced into an extruder for forming a tube, and an outer diameter of 2.0 was obtained.
A tube made of a silicone rubber composition having a diameter of 1.0 mm and an inner diameter of 1.0 mm was formed. At this time, the extrudability and shape retention of the tube made of the silicone rubber composition were good. Then, introduce this tube into a hot air curing oven,
The silicone rubber tube was manufactured by heating at 200 ° C. for 3 minutes. The appearance of the obtained silicone rubber tube was good. The silicone rubber tube 12m was taken out, and 10 points were marked every 1m, and the hardness of the marked point was measured. Here, the hardness is measured according to JIS K62.
The measurement was performed according to the method specified in No. 53 (spring type (A type)). The results of these measurements are shown in Table 2 below.

[0020]

COMPARATIVE EXAMPLE 2 100 parts by weight of dimethylvinylsiloxy group-capped organopolysiloxane rubber (Williams plasticity: 160, weight-average molecular weight: 500,000) comprising 99.6 mol% of dimethylsiloxane units and 0.4 mol% of methylvinylsiloxane units Parts, viscosity at 25 ° C. is 60
3.5 parts of a dimethylsiloxane oligomer capped with silanol groups at both ends of mPa · s and 40 parts of dry-processed silica having a specific surface area of 200 m ² / g were charged into a kneader mixer and heated.
(170 ° C.) and kneaded until uniform to obtain a silicone rubber base. After the silicone rubber base was cooled to 23 ° C., 140 parts of the silicone rubber base had an average molecular formula of Me ₃ SiO (Me ₂ SiO) ₃ (MeHSiO) ₅ Si
0.9 part of a dimethylsiloxane / methylhydrogensiloxane copolymer (having a viscosity of 25 mPa · s) represented by Me ₃ (wherein, Me represents a methyl group), and 1-ethynyl-1- as a hydrosilylation reaction inhibitor. 0.005 parts of cyclohexanol, a complex of chloroplatinic acid and 1,3 divinyltetramethyldisiloxane. 4.6 ppm of platinum atoms, based on 1 million parts of organopolysiloxane raw rubber,
(Weight) and add 3 at 23 ° C on two rolls.
Mix for minutes. Next, the silicone rubber composition was introduced into a tube molding extruder to form a tube made of the silicone rubber composition having an outer diameter of 2.0 mm and an inner diameter of 1.0 mm. At this time, the extrudability and shape retention of the tube made of the silicone rubber composition were good. Then, the tube was introduced into a hot-air curing oven,
For 3 minutes to produce a silicone rubber tube.
The silicone rubber tube 12m was taken out, and 10 points were marked every 1m, and the hardness of the marked points was measured. Here, the hardness was measured according to a method {spring type (A type)} specified in JIS K6253. These measurement results are also shown in Table 2 below.

[0021]

[Table 1]

[0022]

[Table 2]

[0023]

The silicone rubber composition of the present invention is
Since it is composed of the component (A) and the component (B), it can be uniformly mixed in a short time, and has a characteristic that after curing, a uniform silicone rubber molded article can be obtained.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08J 5/00 CFH C08J 5/00 CFH C08K 3/00 C08K 3/00 C08L 83/05 C08L 83/05 83 / 07 83/07 // B29K 83:00 B29K 83:00 B29L 23:24 B29L 23:24 F term (reference) 4F070 AA60 AB11 AC06 AE01 AE08 FA17 FB06 FC02 GA06 GC02 GC04 GC05 4F071 AA67 AB06 AB19 AE17 AG28 AH12 4F201 AA33 AB04 AB11 BA01 BA09 BC01 BC03 BC12 BC37 BD02 BD04 BD05 BK01 BK02 BK13 BK14 BK16 BK26 BK75 BM11 BQ01 BQ04 BQ05 BQ11 4F207 AA33 AB04 AB11 KA01 KF02 KJ06 KJ08 KK12 KW33 4J002 CP04 DE131 DE146 DE116 DA016

Claims (12)

[Claims] (A) (a) Average unit formula: R _a SiO
_{(4-a) / 2} (wherein R is a monovalent hydrocarbon group or a halogenated alkyl group, and a is a number from 1.8 to 2.3), Organopolysiloxane raw rubber having a degree of not less than 50 and containing at least two silicon alkenyls in one molecule (100
Parts by weight), (b) an inorganic filler (1 to 400 parts by weight),
(C) a silicone rubber-based compound comprising a platinum-based catalyst (catalytic amount) and having a Williams plasticity at 25 ° C. in the range of 100 to 1,000; and (B) (a) an average unit formula: R _a SiO _{( 4-a) / 2} (wherein R is a monovalent hydrocarbon group or a halogenated alkyl group, and a is 1.8 to
2.3 number. ), The organopolysiloxane raw rubber (100) having a Williams plasticity of 50 or more and containing two or more silicon alkenyls in one molecule.
Parts by weight), (b) an inorganic filler (1 to 400 parts by weight),
(D) an organohydrogenpolysiloxane containing two or more silicon-bonded hydrogen atoms in one molecule (0.1 to
10 parts by weight) and a silicone rubber base compound having a Williams plasticity at 25 ° C. in the range of 100 to 1,000. 2. The weight average molecular weight of the component (a) is 25 × 10 ^4.
The silicone rubber composition according to claim 1, which is as described above. 3. The ratio between the Williams plasticity at 25 ° C. of the component (A) and the Williams plasticity at 25 ° C. of the component (B) is in the range of (1: 0.8) to (1: 1.2). The silicone rubber composition according to claim 1, wherein 4. The mixing ratio of the component (A) and the component (B) is as follows:
The silicone rubber composition according to claim 1 or 3, wherein the weight ratio is in the range of (1: 0.9) to (1: 1.1). 5. The silicone rubber composition according to claim 1, which is for extrusion molding. 6. A silicone rubber molded article obtained by heating and curing the silicone rubber composition according to claim 1. 7. The following components (A) and (B) are separately produced and stored, and when producing a silicone rubber molded product, the components (A) and (B) are mixed in a mixing apparatus. A method for producing a silicone rubber molded article, comprising introducing and mixing a silicone rubber composition, and then supplying the composition to a silicone rubber molding apparatus and curing by heating. (A) (a) Average unit formula: R _a SiO _{(4-a) / 2} (wherein, R
Is a monovalent hydrocarbon group or a halogenated alkyl group, and a is a number from 1.8 to 2.3. ) And 25
C. has a Williams plasticity of 50 or more, and contains two or more alkenyl silicon-containing organopolysiloxanes in one molecule (100 parts by weight), (b) an inorganic filler (1 to 400 parts by weight), ( C) A silicone rubber-based compound comprising a platinum-based catalyst (catalytic amount) and having a Williams plasticity at 25 ° C. in the range of 50 to 1,000. (B) (a) Average unit formula: R _a SiO _{(4-a) / 2} (where R is a monovalent hydrocarbon group or a halogenated alkyl group,
a is a number from 1.8 to 2.3. ), An organopolysiloxane raw rubber (100 parts by weight) having a Williams plasticity of 50 or more and containing two or more silicon alkenyls in one molecule, (b) an inorganic filler (1 to 40)
0 parts by weight), (d) an organohydrogenpolysiloxane (0.1 to 10 parts by weight) containing two or more silicon-bonded hydrogen atoms in one molecule, and having a Williams plasticity of 100 to 1 at 25 ° C. A silicone rubber-based compound in the range of 10,000. 8. The method for producing a silicone rubber molded article according to claim 7, wherein the weight average molecular weight of (a) is 25 × 10 ⁴ or more. 9. The ratio of the Williams plasticity of the component (A) at 25 ° C. to the Williams plasticity of the component (B) at 25 ° C. is in the range of (1: 0.8) to (1: 1.2). The method for producing a silicone rubber molded article according to claim 7, wherein 10. The compounding ratio of the component (A) and the component (B) in a weight ratio within a range of (1: 0.9) to (1: 1.1). The silicone rubber composition according to the above. 11. The apparatus according to claim 7, wherein the mixing device is a roll mill.
The method for producing a silicone rubber molded product according to the above item. 12. The method according to claim 7, wherein the mixing device is a kneader mixer.