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Abstract

The present invention provides a room-temperature-curable polyorganosiloxane composition which can become a silicone rubber with matte surface and is free from deterioration in physical properties. Specifically, the room-temperature-curable polyorganosiloxane composition comprises: (A) 100 parts by weight of a substantially straight-chain polyorganosiloxane having a viscosity of 20 to 1,000,000 centistokes at 25.degree. C., and having a molecular chain terminal being sealed with a silanol group or a silicon atom-bonded hydrolyzable group; (B) 0.1 to 15 parts by weight of an organic silicon compound having 3 or more silicon atom-bonded hydrolyzable groups in a single molecule; (C) 0 to 15 parts by weight of a condensation reaction catalyst; (D) 100 to 400 parts by weight of a non-treated ground calcium carbonate or a ground calcium carbonate surface-treated with resin acid; and (E) 1 to 200 parts by weight of a non-treated precipitated calcium carbonate or a precipitated calcium carbonate surface-treated with resin acid, wherein at least one of (D) component and (E) component is required to be treated with resin acid, and wherein the amount of (D) component relative to the sum of (D) component and (E) component is within the range of 50 to 99.9% by weight.

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First Claim