Patent ID: 8552108

Claim:
A room temperature curable organopolysiloxane composition comprising (I) 100 parts by weight of an organopolysiloxane which is a condensation product of 80 to 20 parts by weight of the following component (A) and 20 to 80 parts by weight of the following component (B) (with the proviso that total of the components (A) and (B) are 100 parts by weight): (A) an organopolysiloxane comprising R 3 SiO 1/2 unit (wherein R independently represents a substituted or unsubstituted monovalent hydrocarbon group containing 1 to 6 carbon atoms) and SiO 4/2 unit, with the R 3 SiO 1/2 unit being present at 0.6 to 1.2 mol per mole of the SiO 4/2 unit; optionally further comprising R 2 SiO 2/2 unit and RSiO 3/2 unit (wherein R is as defined above) respectively at 0 to 1.0 mol per mole of the SiO 4/2 unit, and containing 0.02 to 0.12 mol/100 g of hydroxy group bonded to the silicon atom, and (B) a diorganopolysiloxane raw rubber having hydroxy group on opposite ends thereof and having a degree of polymerization of at least 5,000, (II) 10 to 50 parts by weight of an organosilane compound having at least 2 hydrolyzable groups bonded to the silicon atom on average per molecule, and/or its partial hydrolytic condensate, (III) 500 to 1,500 parts by weight of a solvent, and (IV) 10 to 150 parts by weight of silica nano particles having their surface modified by a branch structure.