Patent ID: 6780919
Filing Date: 2004-08-24
Classification: C08G,C08L

Abstract:
An organopolysiloxane composition for molding purposes comprising:(A) an organopolysiloxane with at least two alkenyl groups bonded to silicon atoms within a single molecule, having a viscosity at 25Â° C. of 0.05 to 100 PaÂ·s, (B) a straight chain organopolysiloxane with a hydrogen atom bonded to a silicon atom at both terminals and with no aliphatic unsaturated bonds within a molecule represented by a formula (I) shown below: wherein, R is an unsubstituted or substituted monovalent hydrocarbon group with no alkenyl groups, and n is a number such that said organopolysiloxane has a viscosity at 25Â° C. of 0.001 to 1.0 PaÂ·s, (C) an organohydrogenpolysiloxane with at least three hydrogen atoms bonded to silicon atoms within a single molecule and comprising a RHSiO unit and a R2XSiO1/2 unit (wherein R is an unsubstituted or substituted monovalent hydrocarbon group with no alkenyl groups, and X represents a hydrogen atom or a group represented by R as defined above) within a molecule, having a viscosity at 25Â° C. of 0.001 to 1.0 PaÂ·s, (D) an effective quantity of a hydrosilylation reaction catalyst, (E) no more than 50 parts by weight of a finely powdered silica with a specific surface area of at least 50 m2/g, per 100 parts by weight of said constituent (A), and (F) 0 to 20 parts by weight of a non-functional organopolysiloxane having a viscosity at 25Â° C. of 0.01 to 500 PaÂ·s, per 100 parts by weight of said constituent (A), wherein a total number of hydrogen atoms bonded to silicon atoms within said constituent (B) and said constituent (C) is in a range of 1 to 5 atoms per alkenyl group within said constituent (A), and a number of hydrogen atoms bonded to silicon atoms within said constituent (B) accounts for 20 to 70 mol % of a combined number of hydrogen atoms bonded to silicon atoms within said constituent (B) and said constituent (C).