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US 5,290,851 AGranted
Room temperature-curable organopolysiloxane composition
AssigneeDow Corning Toray Silicone Co., Ltd.
InventorsTadao Ishida, Miyoji Fukayama, Noriyuki Suganuma
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Abstract
A room temperature-curable organopolysiloxane composition which does not suffer from surface fissuring even when subjected to external stress (e.g., tensile stress, flexural stress) during the course of its cure was prepared and has a composition of a hydroxyl-terminated polydiorganosiloxane, a hydrophobic silica with a silanol titer not exceeding 2.0 mL, a dry-method silica with a silanol titer of at least 5.0 mL, and an oxime group-containing silane or siloxane.
Claims20
A room temperature-curable organopolysiloxane composition comprising
- (A) 100 parts by weight a hydroxyl-terminated polydiorganosiloxane with a viscosity=0.5 to 500 Pa.s at 25.degree. C.;
- (B) 5 to 50 parts by weight hydrophobic silica whose silanol titer does not exceed 2.0 mL wherein said silanol titer is determined as follows:
- 2.0 g sample is dispersed in a mixture of 25 mL ethanol and 75 mL 20 weight % aqueous NaCl, and the quantity of 0.1N aqueous sodium hydroxide solution required to change the pH of this dispersion from 4.0 to 9.0 is designated as the silanol titer;
- (C) 2 to 10 parts by weight dry-method silica whose silanol titer is at least 5.0 mL wherein said silanol titer is defined in (B);
- and
- (D) 0.5 to 25 parts by weight silane or siloxane which contains at least 3 oxime groups in each molecule.
3 more elements
Dependencies are inferred from the claim text.