Composition of hardenable liquid silicone rubber to form a sealing element and sealing element

摘要

A hardenable liquid silicone rubber composition for forming a sealing element containing a through hole, characterized in that the hardenable liquid silicone rubber composition comprises (A) 100 parts by weight of a liquid organopolysiloxane which is represented by the unit formula average: RaSiO (4-a) / 2 where R is an unsubstituted monovalent hydrocarbyl group or a halogenated monovalent hydrocarbyl group is already from 1.95 to 2.05, which contains at least two silicon-linked alkenyl groups in each molecule, and having a viscosity at 25 ° C of 100 to 100,000 mPa.s; (B) 10 to 100 parts by weight of a reinforcing silica filler; (C) an organohydrogenpolysiloxane having at least two hydrosyl groups in each molecule, in an amount that provides (1.0: 1) to (3.0: 1) for the ratio between the number of moles of hydrosyl groups in this component and the number of moles of alkenyl groups in component (A); (D) a catalyst of the platinum group, in a catalytic amount; (E) a liquid organopolysiloxane that does not contain an unsaturated aliphatic group, hydrosilyl group and silanol group, which has a viscosity at 25 ° C of 10 to 500,000 mPa.s, and that is compatible with component (A), in an amount which is 15 to 31% by weight of the total of the components (A) to (F), where the compatibility of the component (E) with the component (A) is confirmed by the non-generation of turbidity immediately after they have been mixing the two components at room temperature and by not separating in two phases after resting for a prolonged period of time at room temperature; and (F) a liquid organopolysiloxane that does not contain an unsaturated aliphatic group, hydrosylyl group and silanol group, which has a viscosity at 25 ° C of 10 to 500,000 mPa.s, and that is incompatible with component (A), in a amount that is 1.0 to 10% by weight of the total of components (A) to (F), where the incompatibility between component (F) and component (A) is confirmed by turbidity generation immediately after that the two components have been mixed at room temperature or by separation in two phases after resting for a prolonged period of time at room temperature, where the hardened material manufactured from the above has a hardness, measured with a type A durometer according to JIS K 6253, "Hardness Test Method for Vulcanized Rubbers", from 15 to 26 and has a tensile strength at 100% elongation, measured according to JIS K 6251, "Vulcanized Rubbers and Thermoplastic Rubbers - Determination of Tensile Properties", from 0.25 to 0.60 MPa.