JPH07268218A - Silicone rubber composition - Google Patents

Abstract

(57) [Summary] [Object] To provide a silicone rubber composition which, after curing, has a properly adjusted modulus and can be a silicone rubber molded article having high tear strength. [Structure] (A) 100 parts by weight of a silicone rubber composition containing a crosslinkable diorganopolysiloxane as a main component and (B) an average unit formula: (In the formula, R ¹ has a carbon number of 1 to 1 having no aliphatic unsaturated bond.
10 monovalent hydrocarbon groups, R ² is a hydrogen atom, an alkenyl group having 2 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, or a hydroxyl group, and R ³ is 2-1 to 2 carbon atoms.
Is an alkylene group of 0, m is a number of 0 or more, and a,
b is a positive number, c and d are 0 or more numbers, and c + d
Is a positive number. ), And the weight average molecular weight is 1.0
A silicone rubber composition comprising 0.5 to 500 parts by weight of an organosilicon polymer having an amount of 00 or more.

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, and more particularly to a silicone rubber composition which, after curing, can be a silicone rubber molded product having a properly adjusted modulus and a high tear strength.

[0002]

2. Description of the Related Art Conventionally, a silicone rubber composition containing a crosslinkable diorganosiloxane as a main component has been known and is used, for example, for a keyboard pad, a thermos packing, and the like. However, this type of silicone rubber composition has a problem that the silicone rubber molded product after curing has a low tear strength. Further, a high-strength silicone rubber composition containing a silethylene siloxane polymer as a main component (JP-A-4-89866), a silicone rubber composition containing a linear silalkylene siloxane polymer as a main component (JP-A-5-171048, JP-A-5-24
7349 gazette) is proposed. However, obtaining a high molecular weight polymer of these polymers has a problem that the steps for synthesizing the cyclic siloxane and performing ring-opening polymerization are usually long, and the yield of the polymer is low.

[0003]

The present inventors have arrived at the present invention as a result of extensive studies on the above problems. That is, an object of the present invention is to provide a silicone rubber composition which, after curing, has a properly adjusted modulus and can be a silicone rubber molded article having high tear strength.

[0004]

MEANS FOR SOLVING THE PROBLEMS AND ACTIONS OF THE INVENTION In the present invention, 100 parts by weight of a silicone rubber composition containing (A) a crosslinkable diorganopolysiloxane as a main component and (B) an average unit formula:

[Chemical 2] (In the formula, R ¹ has a carbon number of 1 to 1 having no aliphatic unsaturated bond.
10 monovalent hydrocarbon groups, R ² is a hydrogen atom, an alkenyl group having 2 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, or a hydroxyl group, and R ³ is 2-1 to 2 carbon atoms.
Is an alkylene group of 0, m is a number of 0 or more, and a,
b is a positive number, c and d are 0 or more numbers, and c + d
Is a positive number. ), And the weight average molecular weight is 1.0
The present invention relates to a silicone rubber composition characterized by comprising 0.5 to 500 parts by weight of an organosilicon polymer having an amount of 00 or more.

The silicone rubber composition of the present invention will be described in detail below. The silicone rubber composition mainly composed of the crosslinkable diorganopolysiloxane of the component (A) used in the present invention can be cured into a silicone rubber molded article having rubber-like elasticity. Examples thereof include addition reaction curable silicone rubber compositions, condensation reaction curable silicone rubber compositions, and organic peroxide curable silicone rubber compositions.

The addition reaction curable curable silicone rubber composition includes (a) 100 parts by weight of diorganopolysiloxane having a viscosity at 25 ° C. of 40 centipoise or more and having at least two alkenyl groups in one molecule. (B) 0.5 to 90 parts by weight of organohydrogenpolysiloxane having a viscosity at 25 ° C. of 1 to 1,000 centipoise and having 3 or more silicon-bonded hydrogen atoms in one molecule, (c) an inorganic substance 1 to 90 parts by weight of filler and 0.1 to 1,000 parts by weight of platinum metal as platinum metal based on 1 million parts by weight of the total amount of the platinum catalyst (a) and (b). It is preferable that it is a thing.

In this addition reaction-curing type silicone rubber composition, the crosslinkable diorganopolysiloxane as the component (a) is the main agent, has a viscosity at 25 ° C. of 40 centipoise or more, and contains at least two in one molecule. It is necessary to have an alkenyl group of A typical example of the component (a) is an average unit formula: R ⁴ _a SiO _{(4-a) / 2} (wherein
R ⁴ is a monovalent hydrocarbon group, and a is a number of 1.95 to 2.05. ) Is a compound represented by. In the above formula, the monovalent hydrocarbon group of R ⁴ is specifically an alkyl group such as a methyl group, an ethyl group, a propyl group or a butyl group; a vinyl group,
Alkyl groups such as allyl group, butenyl group, pentenyl group, hexenyl group; aryl groups such as phenyl group, tolyl group, xylyl group; aralkyl groups such as benzyl group, phenethyl group; 3-chloropropyl group, 3,3,3 A halo-substituted alkyl group such as a trifluoropropyl group is exemplified, and a methyl group is preferable as the monovalent hydrocarbon group other than the alkenyl group for R ⁴ . Further, in the above formula, a is a number of 1.95 to 2.05. Further, the molecular structure of the component (a) is not particularly limited, and examples thereof include linear, cyclic, reticulated, and partially branched linear, and preferably linear. When the molecular structure of the component (a) is linear, specific examples of the molecular chain end group include trimethylsiloxy group, dimethylvinylsiloxy group, dimethylphenylsiloxy group and dimethylhydroxysiloxy group. To be done. In addition, 2 of the (a) component
The viscosity at 5 ° C. needs to be 40 centipoise or more, and the upper limit thereof may be a raw rubber-like viscosity. This is because if the viscosity of the component (a) is less than 40 centipoise, the physical strength of the cured silicone rubber molded article will decrease.

Specific examples of the diorganopolysiloxane as the component (a) include dimethylpolysiloxane endcapped with dimethylvinylsiloxy groups at both molecular chain ends, a dimethylsiloxane-methylvinylsiloxane copolymer endcapped with dimethylvinylsiloxy groups at both molecular chain ends, Molecular chain both ends dimethylvinylsiloxy group blocked dimethylsiloxane / methylphenylsiloxane copolymer, molecular chain both ends trimethylsiloxy group blocked methylvinylpolysiloxane, molecular chain both ends trimethylsiloxy group blocked dimethylsiloxane / methylvinylsiloxane copolymer, Dimethylsiloxane / methyl (5-hexenyl) siloxane copolymer with both ends of the molecular chain blocked by trimethylsiloxy group, dimethylsiloxane / methylvinylsiloxane with both ends of the molecular chain blocked by dimethylvinylsiloxy group
Examples include methylphenylsiloxane copolymer, methylvinylpolysiloxane blocked with dimethylhydroxy groups at both ends of the molecular chain, and dimethylsiloxane-methylvinylsiloxane copolymer blocked with dimethylhydroxy groups at both ends of the molecular chain.

In this addition reaction-curable silicone rubber composition, the organohydrogenpolysiloxane of component (b) acts as a crosslinking agent, has a viscosity at 25 ° C. of 1 to 1,000 centipoise, and To 3
It is necessary to have at least one silicon-bonded hydrogen atom. A typical example of such component (b) is the average unit formula: R
⁵ _b SiO _{(4-b) / 2} (In the formula, R ⁵ is a monovalent hydrocarbon group or a hydrogen atom excluding an alkenyl group, and b is 1.50 to 3.0.
It is a number of zero. ) Can be represented. In the above formula, R ⁵ is a monovalent hydrocarbon group excluding an alkenyl group or a hydrogen atom, and at least three R ⁵ in the organopolysiloxane molecule represented by the above formula must be hydrogen atoms. . Specific examples of the monovalent hydrocarbon group for R ⁵ include an alkyl group such as a methyl group, an ethyl group, a propyl group and a butyl group;
Aryl groups such as phenyl group, tolyl group and xylyl group; aralkyl groups such as benzyl group and phenethyl group; halo-substituted alkyl groups such as 3-chloropropyl group, 3,3,3-trifluoropropyl group, and the like. It is preferably a group. The molecular structure of the component (b) is not particularly limited, and for example,
Examples thereof include straight-chain, cyclic, network, and partially branched straight-chain, and preferably straight-chain. When the molecular structure of the component (b) is linear, specific examples of the terminal group of the molecular chain include trimethylsiloxy group, dimethylphenylsiloxy group, dimethylhydrogensiloxy group and dimethylhydroxysiloxy group. It In addition, 25 of the component (b)
The viscosity at 0 ° C. needs to be in the range of 1 to 1,000 centipoise, preferably in the range of 5 to 500 centipoise. This is because when the viscosity of the component (b) at 25 ° C. is less than 1 centipoise, the component (b) is easily volatilized and the composition of the obtained silicone rubber composition is not stable. This is because if it exceeds 000 centipoise, the curing time of the obtained silicone rubber composition is too short.

Specific examples of the organohydrogenpolysiloxane as the component (b) include methylhydrogenpolysiloxane blocked with trimethylsiloxy groups at both molecular chain terminals, and dimethylsiloxane / methylhydrogensiloxane copolymerized with trimethylsiloxy groups blocked at both molecular chain terminals. Coupling, dimethylpolysiloxane blocked with dimethylhydrogensiloxy groups at both molecular chain ends, dimethylsiloxane / methylhydrogensiloxane copolymer with dimethylhydrogensiloxy groups blocked at both molecular chain ends, cyclic methylhydrogenpolysiloxane, cyclic methylhydrogensiloxane
A dimethyl siloxane copolymer is illustrated.

In this addition reaction-curable silicone rubber composition, the amount of the component (b) blended must be in the range of 0.5 to 90 parts by weight per 100 parts by weight of the component (a). Further, it is preferably in the range of 1 to 80 parts by weight. This is because if the blending amount of the component (b) is less than 0.5 parts by weight with respect to 100 parts by weight of the component (a), the curability of the obtained silicone rubber composition will be insufficient, Further, if the blending amount exceeds 90 parts by weight, the physical strength of the obtained silicone rubber molded product will decrease.

In this addition reaction curing type silicone rubber composition, various inorganic fillers used in conventionally known silicone rubber compositions can be used as the inorganic filler of the component (c). . Specifically, fumed silica, precipitated silica, carbon black, calcium carbonate, quartz powder, talc, titanium dioxide, aluminum oxide, sericite, reinforcing inorganic filler such as pentonite, glass fiber, asbestos, organic fiber. And the like. As the inorganic filler of the component (c) used in the composition of the present invention, a conventionally known reinforcing silica fine powder is preferable, and as its type, fumed silica fine powder and calcined silica fine powder obtained by a dry method are used. Examples thereof include precipitated silica fine powder obtained by a wet method, and hydrophobic silica fine powder whose surface is treated with dimethyldichlorosilane or hexamethyldisilazane.
Their specific surface area is more than 50 m ² / g, but 100
It is preferably in the range of to 400 m ² / g.

In this addition reaction-curable silicone rubber composition, the amount of component (c) to be blended must be in the range of 1 to 90 parts by weight per 100 parts by weight of component (a). It is preferably in the range of 1 to 80 parts by weight. This is because if the content of the component (c) exceeds 90 parts by weight with respect to 100 parts by weight of the component (a), the curability of the obtained silicone rubber composition will be insufficient.
This is because if the blending amount is less than 1 part by weight, the physical strength of the obtained silicone rubber molded article will decrease.

The platinum-based catalyst of component (d) is composed of component (a) and component (b).
It is a catalyst for accelerating the addition reaction of components and curing. Specific examples of the component (d) include chloroplatinic acid, an alcohol solution of chloroplatinic acid, a complex of chloroplatinic acid and an olefin, a complex of chloroplatinic acid and vinylsiloxane, a complex of chloroplatinic acid and ketones, Examples include platinum-supported alumina fine powder, platinum-supported silica fine powder, and platinum black. The blending amount of the component (d) is not particularly limited as long as it is a catalytic amount, and the total amount of the components (a) and (b) is preferably 100.
The amount is 1 to 1,000 parts by weight as platinum metal based on 10,000 parts by weight.

In addition to the above components (a) to (d), an addition reaction inhibitor is added to the addition reaction curable silicone rubber composition in order to impart storage stability of the composition at room temperature. It can be blended. Specifically as the addition reaction inhibitor, 3-methyl-1-butyn-3-ol,
Alkynyl alcohols such as 3,5-dimethyl-1-hexyn-3-ol, 3-methyl-1-penten-3-ol, phenylbutynol; 3-methyl-3-penten-1-yne, 3,5- Examples thereof include dimethyl-1-hexyne-3-yne, benzotriazole, and methylvinylsiloxane cyclic compounds. The addition amount of such an addition reaction inhibitor is optional and is preferably 0.1 part by weight per 100 parts by weight of component (a).
It is in the range of 001 to 5 parts by weight.

As the condensation reaction-curable silicone rubber composition, (a ') a diorganopolysiloxane having a viscosity of 40 centipoise or more at 25 ° C. and having at least two silanol groups in one molecule. 100 parts by weight, (b ') the general _{formula: R' e SiX 4-e} ( wherein, R 'is a monovalent hydrocarbon group substituted or unsubstituted C1-8, e is 0, 1 , Or 2, and X is a moisture-hydrolyzable group) 0.5 to 90 parts by weight of an organosilane or a partial hydrolyzed condensate thereof, (c ′) an inorganic filler 1 to 90 parts by weight, and (d ') Condensation reaction accelerating catalyst It is preferably a silicone rubber composition comprising 0.01 to 20 parts by weight.

In this condensation reaction-curable silicone rubber composition, the component (a '), the diorganopolysiloxane, is the main agent, has a viscosity at 25 ° C. of 40 centipoise or more, and contains at least two diorganopolysiloxanes per molecule. It is necessary to have a silanol group. Representative examples of such component (a ') the average unit formula: R ⁶ _c SiO in _{(4-c) / 2} (wherein, R ⁶
Is a monovalent hydrocarbon group or a silanol group, and c is 1.
It is a number from 95 to 2.05. ) Can be represented. In the above formula, R ⁶ is a monovalent hydrocarbon group or a silanol group, and at least two R ⁶ of the diorganopolysiloxane molecule represented by the above formula must be silanol groups. Specific examples of the monovalent hydrocarbon group for R ⁶ include an alkyl group such as a methyl group, an ethyl group, a propyl group and a butyl group;
Alkenyl groups such as vinyl group, allyl group, butenyl group, pentenyl group, hexenyl group; aryl groups such as phenyl group, tolyl group, xylyl group; aralkyl groups such as benzyl group, phenethyl group; 3-chloropropyl group, 3, A halo-substituted alkyl group such as a 3,3-trifluoropropyl group is exemplified, and a methyl group is preferable. Also, in the above formula, c
Is a number from 1.95 to 2.05. The molecular structure of the component (a ') is not particularly limited, and examples thereof include linear, cyclic, network, and partially branched ones, but the linear structure is preferable. Further, when the molecular structure of the component (a ') is linear, specific examples of the molecular chain terminal group include a dimethylhydroxysiloxy group and a methylphenylhydroxysiloxy group. In addition, the component (a ') at 25 ℃
It is necessary that the viscosity in (4) is 40 centipoise or more, and the upper limit thereof can be a raw rubber-like viscosity. This is because the viscosity of component (a ') is 4
This is because if it is less than 0 centipoise, the penetration of the silicone rubber composition after curing into the substrate becomes too large.
When using the composition of the present invention as a solventless type,
The viscosity of the component (a ′) at 25 ° C. is 40 to 10,000.
It is preferably in the range of centipoise, and further 10
It is preferably in the range of 0 to 5,000 centipoise. Further, when the composition of the present invention is used as a solvent type, the viscosity of the component (a ′) at 25 ° C. is 100,00.
It is preferably from 0 centipoise to a viscosity showing a raw rubber-like morphology, and more preferably from 500,000 centipoise to a viscosity showing a raw rubber-like morphology.

Specific examples of the diorganopolysiloxane of the component (a ') include dimethylpolysiloxane endblocked by dimethylhydroxysiloxy groups at both molecular chain ends, and dimethylsiloxane-methylvinylsiloxane copolymer endblocked by dimethylhydroxysiloxy groups at both molecular chain ends. , A dimethylhydroxysiloxy group-blocked dimethylsiloxane / methylphenylsiloxane copolymer with both molecular chain ends, a dimethylhydroxysiloxy group-blocked methylvinylpolysiloxane with both molecular chain ends,
Methylphenylpolysiloxane copolymer with dimethylhydroxysiloxy groups blocked at both ends of the molecular chain, dimethylhydroxysiloxy group-blocked dimethylsiloxane methyl (5-hexenyl) siloxane copolymer with both ends of the molecular chain, dimethylhydroxysiloxy group blocked at both ends of the molecular chain A phenyl polysiloxane is illustrated.

In this condensation reaction-curing type silicone rubber composition, the organosilane of component (b ') or its partial hydrolysis-condensation product acts as a crosslinking agent and functions to cure the composition of the present invention at room temperature. . In the formula, e is 0, 1 or 2, but is preferably 1. X is a moisture-hydrolyzable group, which is a diorganoketoxime group, an alkoxy group, an acyloxy group, a monoorganoamino group, a diorganoamino group, an N-organoacylamino group, an N, N-diorganohydroxyamino group, an alkenyloxy group. There are groups, etc. Specific examples thereof include a dimethylketoxime group, a methylethylketoxime group, a methoxy group, an ethoxy group, an acetoxy group, an N-butylamino group, a methylacetamide group, an N, N-diethylhydroxyamino group and a propenoxy group. R'is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 8 carbon atoms, and e is 0, 1 or 2
And specific examples include methyl group, ethyl group, tert-
Butyl group, 2-ethylhexyl group, dodecyl group, octadecyl group and other alkyl groups, vinyl group, allyl group, hexadienyl group and other alkenyl groups, cyclopentyl group,
Cycloalkyl group such as cyclohexyl group, cycloalkenyl group such as cyclopentenyl group and cyclohexenyl group, aryl group such as phenyl group and naphthyl group, aralkyl group such as benzyl group, phenylethyl group and xylyl group, tolyl group, dimethyl group Alkaryl group such as phenyl group, halogenated hydrocarbon group such as chloromethyl group, chloropropyl group, 3,3,3-trifluoropropyl group,
_{F (CF 2) a CH 2} CH 2 - groups (a is as defined above) and the like fluoroalkyl groups such as. A good example is
Examples thereof include a methyl group and a vinyl group.

The blending amount of the component (b ') must be in the range of 0.5 to 90 parts by weight, and further in the range of 1 to 80 parts by weight, relative to 100 parts by weight of the component (a'). It is preferable. This is because if the blending amount of the component (b ') is less than 0.5 parts by weight relative to 100 parts by weight of the component (a'), the obtained silicone rubber composition will be insufficiently cured. Further, if the blending amount exceeds 90 parts by weight, the physical strength of the obtained silicone rubber molded article is lowered. In particular, the amount of the hydroxyl group bonded to the silicon atom of the component (a '),
Considering the content of the moisture-hydrolyzable group X in the component (b '), the amount that can be stored for a long time in the absence of moisture and is necessary for curing at room temperature in the presence of moisture is selected.

The inorganic filler as the component (c ') is the same as the component (c) described in the addition reaction-curing type silicone rubber composition, and the same ones are exemplified.

The condensation reaction accelerating catalyst of the component (d ') is a catalyst for accelerating the condensation reaction of the components (a') and (b ') to cure the composition. Such catalysts are usually
Those used for dehydration condensation of silanol groups are effective. Specifically, dibutyltin acetate, dibutyltin laurate, dibutyltin dioctoate, octoic acid primary
Tin, stannous naphthenate, stannous oleate, stannous isobutyrate, stannous linoleate, stannous stearate, stannous benzoate, stannous naphthoate, stannous laurate,
O-stannic acid stannous, β-benzoylpropionic acid primary
Tin, stannous crotonic acid, stannous trobaate, stannous P-bromobenzoate, stannous palmitooleate, cinnamic acid first
Examples thereof include tin and tin salts of carboxylic acids such as stannous salt of phenylacetic acid, iron salts, manganese salts or cobalt salts of these carboxylic acids, tetraalkyl titanates, complex salts of dialkyl titanates, organosiloxy titanates, and the like. It is preferable to select and use the one suitable according to the kind of the moisture-hydrolyzable group of the component b '). The blending amount of the component (d ') is 0.01 with respect to 100 parts by weight of the component (a').
It is necessary to be in the range of 20 parts by weight.

Examples of the organic peroxide-curable silicone rubber composition include (a ") 100 parts by weight of diorganopolysiloxan having at least two alkenyl groups in one molecule, (c") inorganic filler 1 ˜90 parts by weight and (d ″) organic peroxide 0.01 to 20 parts by weight are preferred.

In this organic peroxide-curable silicone rubber composition, the diorganopolysiloxane of component (a ") is the main agent and must have at least two alkenyl groups in each molecule. A typical example of such component (a ") is the average unit formula: R ⁴ _a SiO _{(4-a) / 2} (wherein
R ⁴ is a monovalent hydrocarbon group, and a is a number of 1.95 to 2.05. ) Is a compound represented by. In the above formula, the monovalent hydrocarbon group of R ⁴ is specifically an alkyl group such as a methyl group, an ethyl group, a propyl group or a butyl group; a vinyl group,
Alkyl groups such as allyl group, butenyl group, pentenyl group, hexenyl group; aryl groups such as phenyl group, tolyl group, xylyl group; aralkyl groups such as benzyl group, phenethyl group; 3-chloropropyl group, 3,3,3 Examples include halo-substituted alkyl groups such as trifluoropropyl group, provided that at least two R ^{4 s} in the organopolysiloxane molecule represented by the above formula are alkenyl groups exemplified above. ^A methyl group is preferable as the monovalent hydrocarbon group other than the alkenyl group of ⁴ . In the above formula, a is 1.9.
It is a number of 5 to 2.05. Further, the molecular structure of the component (a ") is not particularly limited, and examples thereof include linear, cyclic, network, and partially branched linear, and preferably linear.
In addition, the diorganopolysiloxane of the component (a ") is 2
From those showing a viscosity of 100,000 centipoise at 5 ° C., those having a high viscosity showing a raw rubber-like form are preferable, and those having a high viscosity showing a raw rubber-like form are particularly preferable. When the component (a ") has a linear molecular structure, specific examples of the molecular chain end group include a trimethylsiloxy group, a dimethylvinylsiloxy group, a dimethylphenylsiloxy group and a dimethylhydroxysiloxy group. It is illustrated.

Specific examples of the diorganopolysiloxane of the component (a ") include dimethylpolysiloxane endblocked by dimethylvinylsiloxy groups at both molecular chain ends, and dimethylsiloxane-methylvinylsiloxane copolymer endblocked by dimethylvinylsiloxy groups at both molecular chain ends. , Dimethylsiloxane / methylphenylsiloxane copolymer capped with dimethylvinylsiloxy groups at both molecular chain ends, methylvinylpolysiloxane with trimethylsiloxy group capped with trimethylsiloxy groups at both molecular chain ends, dimethylsiloxane / methylvinylsiloxane copolymer with trimethylsiloxy groups capped at both molecular chain ends , Dimethylsiloxy / methyl (5-hexenyl) siloxane copolymer with trimethylsiloxy groups blocked at both ends of the molecular chain, dimethylvinylsiloxy / methylphenylsiloxane with dimethylvinylsiloxy groups blocked at both ends of the molecular chain Hexane copolymers, dimethylpolysiloxane with both molecular chain terminals hydroxy groups blocked methylvinylpolysiloxane,
An example is a dimethylsiloxane / methylvinylsiloxane copolymer in which both ends of the molecular chain are dimethylhydroxy groups.

The inorganic filler as the component (c ") is the same as the component (c) described in the addition reaction-curing type silicone rubber composition, and the same ones are exemplified.

The organic peroxide of component (d ") is benzoyl peroxide, dicumyl peroxide, ditertiary-butyl peroxide, tert-butyl monochlorobenzoylperoxide, 2,5-dimethyl-2,
5-di (tert-butyl-peroxy) hexane etc. are illustrated. The blending amount of the component (d ") needs to be in the range of 0.01 to 20 parts by weight with respect to 100 parts by weight of the component (a").

If necessary, additives such as an internal mold release agent, a heat resistance additive, a sealing aging improver, an adhesion improver, a dye and a pigment may be added to these silicone rubber compositions. it can. Further, these silicone rubber compositions can be used as a dispersion prepared by dissolving the silicone rubber composition in an organic solvent.

The silicone rubber composition of the present invention comprises 100 parts by weight of a silicone rubber composition containing the above-mentioned (A) crosslinkable diorganopolysiloxane as a main component and a general formula:

[Chemical 3] (In the formula, R ¹ has a carbon number of 1 to 1 having no aliphatic unsaturated bond.
10 monovalent hydrocarbon groups, R ² is a hydrogen atom, an alkenyl group having 2 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, or a hydroxyl group, and R ³ is 2-1 to 2 carbon atoms.
Is an alkylene group of 0, m is a number of 0 or more, a,
b is a positive number, c and d are numbers 0 or more, and c + d
Is a positive number. ), The weight average molecular weight is 100
It is characterized by comprising 0.5 to 500 parts by weight of an organosilicon polymer which is 0 or more. This organosilicon polymer is
It acts as a component for imparting an appropriate modulus to a silicone rubber molded product obtained by curing a silicone rubber composition containing this, and particularly serves to improve the tear strength. In the above formula, R ¹ is a monovalent hydrocarbon group having 1 to 10 carbon atoms having no aliphatic unsaturated bond, and specifically, methyl group, ethyl group, propyl group, butyl group, pentyl group, octyl group. Groups such as alkyl groups; phenyl groups, tolyl groups, xylyl groups, and other aryl groups; benzyl groups, phenethyl groups, and other aralkyl groups; 3-chloropropyl groups, 3,
A halo-substituted alkyl group such as a 3,3-trifluoropropyl group is exemplified, and a methyl group is preferable. In the above formula, R ³ is an alkylene group having 2 to 10 carbon atoms, and specific examples thereof include ethylene group, propylene group, butylene group, pentylene group, hexylene group and octylene group.
Further, in the above formula, R ² is any one of a hydrogen atom, an alkenyl group having 2 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, and a hydroxyl group. Specific examples of the alkenyl group for R ² include a vinyl group, an allyl group, a butenyl group, a pentenyl group,
Examples thereof include a hexenyl group and an octenyl group, and specific examples of the alkoxy group for R ² include a methoxy group, an ethoxy group, a propoxy group and a butoxy group. In the case of using an addition reaction curable silicone rubber composition in the silicone rubber composition of the present invention, R ² is preferably a hydrogen atom or an alkenyl group having 2 to 10 carbon atoms, and a condensation reaction curable type. When the above silicone rubber composition is used, R ² is preferably a hydrogen atom, a hydroxyl group or an alkoxy group, and when an organic peroxide-curable silicone rubber composition is used, the component (B) of R ^{2 of the} organosilicon polymer is preferably an alkenyl group having 2 to 10 carbon atoms. Further, in the above formula, m is a number of 0 or more, a and b are positive numbers, c and d are numbers of 0 or more, and c + d is a positive number.

The viscosity of the organosilicon polymer as the component (B) at 25 ° C. is not particularly limited, and the silicone rubber composition obtained has excellent handling workability and the obtained silicone rubber molded product has good physical properties. Because there is 10
It is preferably in the range of 10,000 centistokes. Further, by adjusting the amount of the organosilicon polymer compounded, the physical properties of the resulting cured silicone rubber can be adjusted.

Specific examples of the organosilicon polymer as the component (B) include the following compounds. In the formula,
Me represents a methyl group, Vi represents a vinyl group, Ph represents a phenyl group, a, b, c, d, m, v, w, x,
y is a positive number. _{(CH 2 = CHC 4 H 8} Me 2 SiO 1/2) a (O 1/2 Me 2 Si
_{C 6 H 12 Me 2 SiO 1/2} ) b - (MeSiO 3/2) c (CH 2 = CHC 4 H 8 Me 2 SiO 1/2) a (O 1/2 Me 2 Si
_{C 6 H 12 Me 2 SiO 1/2} ) b - (SiO 4/2) d (ViMe 2 SiO 1/2) a (O 1/2 Me 2 SiC 2 H 4 Me 2 S
iO _1/2 ) _b (SiO _4/2 ) _d (ViMe ₂ SiO _1/2 ) _a (O _1/2 Me ₂ SiC ₂ H ₄ Me ₂ S
iO _1/2 ) _b- (MeSiO _3/2 ) _c (ViMe ₂ SiO _1/2 ) _a (O _1/2 Me ₂ SiC ₂ H ₄ Me ₂ S
_{iO 1/2) b - (CF 3} C 2 H 4 SiO 3/2) c (ViMe 2 SiO 1/2) a (O 1/2 MePhSiC 2 H 4 Me
_{PhSiO 1/2) b - (MeSiO 3/2} ) c (ViMePhSiO 1/2) a (O 1/2 MePhSiC 2 H 4 M
_{ePhSiO 1/2) b - (MeSiO 3/2} ) c (HMe 2 SiO 1/2) v (O 1/2 Me 2 SiC 6 H 12 Me 2 Si
_{O 1/2) w - (MeSiO 3/2} ) x (HMe 2 SiO 1/2) v (O 1/2 Me 2 SiC 2 H 4 Me 2 Si
O _1/2 ) _w (MeSiO _3/2 ) _x (HMe ₂ SiO _1/2 ) _v (O _1/2 Me ₂ SiC ₆ H ₁₂ Me ₂ Si
O _1/2 ) _w (SiO _4/2 ) _y (HMe ₂ SiO _1/2 ) _v (O _1/2 Me ₂ SiC ₂ H ₄ Me ₂ Si
O _1/2 ) _w (SiO _4/2 ) _y (HMe ₂ SiO _1/2 ) _v (O _1/2 Me ₂ SiC ₂ H ₄ Me ₂ Si
O _1/2 ) _w- (CF ₃ C ₂ H ₄ SiO _3/2 ) _x (HMe ₂ SiO _1/2 ) _v (O _1/2 MePhSiC ₂ H ₄ MeP
hSiO _1/2 ) _w- (MeSiO _3/2 ) _x (HMePhSiO _1/2 ) _v (O _1/2 MePhSiC ₂ H ₄ Me
PhSiO _1/2 ) _w- (MeSiO _3/2 ) _x (HOMe ₂ SiO _1/2 ) _v (O _1/2 Me ₂ SiC ₆ H ₁₂ Me ₂ S
iO _1/2 ) _w- (MeSiO _3/2 ) _x (MeOMe ₂ SiO _1/2 ) _v (O _1/2 Me ₂ SiC ₆ H ₁₂ Me ₂
SiO _1/2 ) _w- (MeSiO _3/2 ) _x

The method for producing such an organosilicon polymer is not particularly limited, and for example, the general formula: R ¹ Si (OR ¹
₂ SiH) ₃ (wherein R ¹ is a monovalent hydrocarbon group having 1 to 10 carbon atoms and having no aliphatic unsaturated bond), and / or a general formula: Si (OR
¹ ₂ SiH) ₄ (wherein R ¹ is the same as above) and, if necessary, the general formula: HR
A diorganosiloxane represented by the formula: ¹ ₂ SiO (R ¹ ₂ SiO) _p R ¹ ₂ SiH (wherein R ¹ is the same as above, and p is a number of 0 or more), and a general formula: _{^{R 4 R 1 2 SiO (R}} 1
₂ SiO) _p R ¹ ₂ SiR ⁴ (In the formula, R ¹ is a monovalent hydrocarbon group having 1 to 10 carbon atoms and having no aliphatic unsaturated bond,
⁴ is an alkenyl group having 2 to 10 carbon atoms, and p is the same as above. ), An unsaturated aliphatic hydrocarbon having 3 to 10 carbon atoms having 2 carbon-carbon double bonds, or 2 to 10 carbon atoms having 1 carbon-carbon triple bond Examples thereof include a method of addition-polymerizing an unsaturated aliphatic hydrocarbon with platinum or a platinum compound. Further, in the case where a silicon atom-bonded hydrogen atom remains as a terminal in the organosilicon polymer thus obtained, this can be easily converted into an alkoxy group or a hydroxyl group.

Further, the general _{^{formula: XR 1 2 Si-R 3}} -SiR 1 2
X (in the formula, R ¹ is a C ¹ having no aliphatic unsaturated bond)
10 is a monovalent hydrocarbon group, X is a hydrolyzable group, and R ³ is an alkylene group having 2 to 10 carbon atoms. Silicon compound represented by), the general formula:. XR ¹ ₂ SiR ₅ (In the formula, R ¹ and X are as defined above, R ₅ is an alkenyl group of a hydrogen atom or 2 to 10 carbon atoms) with silicon compounds represented, and the general formula: XSiR ¹ ₃ (in the formula, R ¹ and X are as defined above.) a silicon compound represented by, or the formula: X ₄ Si (wherein, X is the The same method as the above) is used to co-hydrolyze the organosilicon compound and condensation polymerization is carried out with an acidic or basic catalyst. X in the above formula is a hydrolyzable group, specifically, a halogen atom such as a chlorine atom or a bromine atom, or a methoxy group,
Examples thereof include alkoxy groups such as ethoxy group and propoxy group.

In the silicone rubber composition of the present invention,
The amount of the organosilicon polymer as the component (B) is 0.5 to 50 with respect to 100 parts by weight of the silicone rubber composition as the component (A).
It must be in the range of 0 parts by weight. In the addition reaction curable silicone rubber composition, the amount of the organosilicon polymer compounded is preferably 1.0 to 500 parts by weight per 100 parts by weight of the diorganopolysiloxane of component (a), Further, it is preferably from 2.0 to 200 parts by weight. In the condensation reaction-curable silicone rubber composition, the amount of the organosilicon polymer compounded is preferably 1.0 to 500 parts by weight based on 100 parts by weight of the diorganopolysiloxane (a '). , And 2.
It is preferably from 0 to 200 parts by weight. Further, in the organic peroxide-curable silicone rubber composition, the content of the organosilicon polymer is 1.0 to 500 parts by weight based on 100 parts by weight of the diorganopolysiloxane of the component (a "). It is preferable that the amount is 2.0 to 200 parts by weight.

The silicone rubber composition of the present invention has the above-mentioned composition.
It can be easily produced by uniformly mixing the components (A) and (B) with a kneader mixer, Banbury mixer, two-roll mixer or the like. In this case
The silicone rubber composition of component (A) is manufactured in advance,
The organosilicon compound as the component (B) may be added and blended thereto, or the organosilicon compound as the component (B) may be added and blended in the process of producing the silicone rubber composition as the component (A).
The conditions for curing the silicone rubber composition of the present invention are not particularly limited, but the molding temperature is 25 to 200 ° C.
Is the range.

The silicone rubber composition of the present invention as described above becomes a silicone rubber molded product having an appropriately adjusted modulus and a high tear strength after curing, and therefore, it is used in applications requiring such characteristics. For example, it is useful as a silicone rubber composition applied to a keyboard, a thermos packing, and the like.

[0037]

EXAMPLES The silicone rubber composition of the present invention will be described in detail below with reference to examples. In the examples, the viscosity is a value at 25 ° C.

[0038]

Example 1 A vinyl group-containing diorganopolysiloxane having 99.5 mol% of dimethylsiloxane units and 0.2 mol% of methylvinylsiloxane units and having an average degree of polymerization of 7,000 blocked at the ends with dimethylvinylsiloxy groups. 1
00 parts, fumed silica 35 having a specific surface area of 200 m ² / g whose surface is hydrophobized with dimethyldichlorosilane 35
The parts were put into a kneader mixer and kneaded until uniform. Then, it was heated at 120 ° C. for 2 hours to obtain a silicone rubber base. 135 parts of this silicone rubber base has a viscosity of 110 centipoise and has the formula:

[Chemical 4] (In the formula, the ratio of a: b: c is 0.96: 1.02: 1.), A branched organosilicon polymer which is soluble in toluene and has a weight average molecular weight of 6,000. Add 15 parts by weight, 10 parts by weight of quartz fine powder, and 0.5 parts of 2,5-dimethyl-2,5-di (tert-butylperoxy) hexane, and mix with a two-roll mill until uniform. A silicone rubber composition was obtained. The obtained silicone rubber composition was treated at 170 ° C. under a pressure of 30 kg / cm ² for 10
A silicone rubber sheet having a thickness of 2 mm was obtained by compression molding for 1 minute. The sheet was further heated at 200 ° C. for 4 hours in an oven, and the physical properties of the sheet were measured according to JISK6301. The results are shown in Table 1.

[0039]

Comparative Example 1 A silicone rubber composition was prepared in the same manner as in Example 1 except that the branched organosilicon polymer was not blended, and then vulcanized in the same manner to obtain a silicone rubber sheet. The physical strength of this sheet was measured, and the results are shown in Table 1.

[0040]

Example 2 100 parts by weight of a dimethylvinylsiloxy group-capped dimethylsiloxane / methylvinylsiloxane copolymer having a molecular chain at both ends and a viscosity of 2,000 centipoise (vinyl group content = 0.8% by weight), viscosity 20 Centipoise, 3 parts by weight of methyl hydrogen polysiloxane blocked with trimethylsiloxy groups at both ends of the molecular chain, viscosity 14
0 centipoise, formula:

[Chemical 5] (In the formula, the ratio of a: b: c is 0.92: 2.08: 1.), A branched organosilicon polymer soluble in toluene and having a weight average molecular weight of 5,000. 15 parts by weight of 30 parts of fumed silica having a specific surface area of 180 m ² / g whose surface was previously hydrophobized with hexamethyldisilazane were charged into a kneader mixer and kneaded until uniform. Then, heat treatment was carried out at 100 ° C. for 2 hours to obtain a silicone rubber base. This silicone rubber base 1
To 48 parts, 0.9 part by weight of methylbutinol was uniformly mixed. Then, a solution of chloroplatinic acid in isopropyl alcohol was uniformly mixed with the dimethylsiloxane / methylvinylsiloxane copolymer so that the platinum metal in chloroplatinic acid was 50 ppm, to give a silicone rubber composition. Was prepared. The obtained silicone rubber composition,
A silicone rubber sheet was obtained by curing in the same manner as in Example 1, and the physical properties of the sheet were measured in the same manner as in Example 1. The results are shown in Table 1.

[0041]

Comparative Example 2 A silicone rubber composition was prepared in the same manner as in Example 2 except that the branched organosilicon polymer was not added, and vulcanized in the same manner to obtain a silicone rubber sheet. The physical strength of this sheet was measured, and the results are shown in Table 1.

[0042]

[Example 3] Dimethylpolysiloxane 1 having a silanol group at both ends of a molecular chain and having a viscosity of 2,000 centipoise
100 parts by weight, viscosity 10 centipoise, viscosity 110
Centipoise and formula:

[Chemical 6] (In the formula, the ratio of a: b: c is 0.94: 1.03: 1.), A branched organosilicon polymer which is soluble in toluene and has a weight average molecular weight of 4,600. 10 parts by weight of 15 parts of fumed silica having a specific surface area of 180 m ² / g whose surface was previously hydrophobized with hexamethyldisilazane were charged into a kneader mixer and kneaded until uniform. Then, heat treatment was carried out at 100 ° C. for 2 hours to obtain a silicone rubber base. This silicone rubber base 1
A silicone rubber composition was prepared by uniformly mixing 25 parts by weight of 7 parts by weight of methyltrimethoxysilane and 1.5 parts by weight of tetrabutyl titanate. The obtained silicone rubber composition was extrusion molded as a silicone rubber sheet having a thickness of 2 mm and left at room temperature for 2 weeks to obtain a cured rubber sheet. The physical properties of this sheet were measured according to JIS K6301. The results are shown in Table 2.

[0043]

Comparative Example 3 A silicone rubber composition was prepared in the same manner as in Example 3 except that the branched organosilicon polymer was not blended, and vulcanized in the same manner to obtain a silicone rubber sheet. The physical strength of this sheet was measured, and the results are shown in Table 2.

[0044]

[Table 1]

[0045]

[Table 2]

[0046]

The silicone rubber composition of the present invention comprises (A)
It consists of a silicone rubber composition mainly composed of a cross-linkable diorganopolysiloxane as a component and a predetermined amount of a special organosilicon compound as a component (B), so that it has an appropriately adjusted modulus after curing and high tear strength. It has a feature that it can be a molded silicone rubber product.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location C08L 83/14 LRM

Claims (4)

[Claims] 1. A silicone rubber composition comprising 100 parts by weight of (A) a crosslinkable diorganopolysiloxane as a main component and (B) an average unit formula: (In the formula, R ¹ has a carbon number of 1 to 1 having no aliphatic unsaturated bond.
10 monovalent hydrocarbon groups, R ² is a hydrogen atom, an alkenyl group having 2 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, or a hydroxyl group, and R ³ is 2-1 to 2 carbon atoms.
Is an alkylene group of 0, m is a number of 0 or more, and a,
b is a positive number, c and d are 0 or more numbers, and c + d
Is a positive number. ), And the weight average molecular weight is 1.0
A silicone rubber composition comprising 0.5 to 500 parts by weight of an organosilicon polymer having an amount of 00 or more. 2. A silicone rubber composition comprising a crosslinkable diorganopolysiloxane as a component (A) as a main component, wherein (a) the viscosity at 25 ° C. is 40 centipoise or more, and at least two alkenyl groups are contained in one molecule. 100 parts by weight of a diorganopolysiloxane having (b), (b) an organohydrogenpolysiloxane having a viscosity at 25 ° C. of 1 to 1,000 centipoise and having 3 or more silicon atom-bonded hydrogen atoms in one molecule 0.5. To 90 parts by weight, (c) 1 to 90 parts by weight of inorganic filler, and (d) platinum-based catalyst 0.1 to 1 as platinum metal based on the total amount of 1 million parts by weight of the components (a) and (b). The silicone rubber composition according to claim 1, wherein the silicone rubber composition comprises 1,000 parts by weight. 3. A silicone rubber composition comprising, as a main component, a crosslinkable diorganopolysiloxane as component (A), (a ′) has a viscosity at 25 ° C. of 40 centipoise or more and at least 2 in one molecule. diorganopolysiloxane 100 parts by weight having a silanol group, (b ') the general _{formula: R' e SiX 4-e} ( wherein, R 'is a substituted or unsubstituted monovalent hydrocarbon having 1 to 8 carbon atoms Group, e is 0, 1, or 2, and X is a moisture-hydrolyzable group. 0.5 to 90 parts by weight of organosilane or a partial hydrolyzed condensate thereof, (c ′) The silicone rubber composition according to claim 1, which comprises 1 to 90 parts by weight of an inorganic filler and 0.01 to 20 parts by weight of a (d ') condensation reaction accelerating catalyst. 4. A silicone rubber composition comprising, as a main component, a crosslinkable diorganopolysiloxane as the component (A) is (a ") 100 parts by weight of diorganopolysiloxane having at least two alkenyl groups in one molecule. The silicone rubber composition according to claim 1, which comprises 1 to 90 parts by weight of (c ") an inorganic filler and 0.01 to 20 parts by weight of (d") an organic peroxide.