US 5,179,148 AGranted

Silicone rubber composition and method for the preparation thereof

AssigneeShin-Etsu Chemical Co., Ltd.

InventorsYoshio Inoue, Masachika Yoshino, Masaharu Takahashi

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Abstract

A silicone rubber composition having excellent workability and extrusion-moldability and capable of giving cured silicone rubber articles having good mechanical properties is proposed, which is prepared by admixing, in addition to the conventional ingredients of an organopolysiloxane gum, a finely divided reinforcing silica filler and a curing agent such as an organic peroxide, a low molecular-weight organopolysiloxane having, in a molecule, at least three silanolic hydroxy groups which serves as a wetting agent of the silica filler so as to improve the compatibility of the silica filler with the organopolysiloxane gum giving a possibility of increasing the amount of the silica filler without adverse influences such as a decrease in the plasticity of the composition.

Claims14

Dependent claims

A silicone rubber composition which comprises, as a blend:

(a) 100 parts by weight of an organopolysiloxane represented by the average unit formula
R.sub.a SiO.sub.(4-1)/2,
in which R is an unsubstituted or substituted monovalent hydrocarbon group and the subscript a is a positive number in the range from 1.95 to 2.05, having an average degree of polymerization of at least 3000;
(b) from 0.1 to 20 parts by weight of an organopolysiloxane having at least three silanolic hydroxy groups per molecule, said organopolysiloxane represented by the average unit formula
R.sup.1.sub.m (OH).sub.n SiO.sub.(4-m-n)/2,
in which R.sup.1 is an unsubstituted or substituted monovalent hydrocarbon group, the subscript m is a positive number in the range from 1 to 2 and the subscript n is a positive number not exceeding 1 with the proviso that m+n is larger than 1 but not exceeding 3;
(c) from 5 to 50 parts by weight of a finely divided silica filler having a specific surface area of at least 50 m.sup.2 /g;
and
(d) a curing agent in an amount sufficient to cure the composition.

6 more elements

Dependencies are inferred from the claim text.