ROOM TEMPERATURE CURING ORGANOPOLYSILOXANES

摘要

1,272,344. Organopolysiloxane composition. DOW CORNING CORP. 6 Nov., 1970 [9 Jan., 1970; 1 April, 1970], No. 52833/70. Heading C3T. A room temperature curable composition comprises (a) 100 parts by weight of a hydroxylterminated polysiloxane of units RRfSiO in which R is a C 1-6 alkyl, and Rf is a beta-perfluoroalkylethyl radical of from 3-12 carbon atoms, and having a viscosity of at least 100 cs. at 25‹ C.; (b) from 0À5-20 parts by weight of a silane R1SiX 3 or mixtures of silanes in which R1 is a phenyl or vinyl radical, and X is a methoxy or ethoxy radical; and (c) from 0À1 to 10 parts by weight of a carboxylic acid salt of metals from Pb to Mn in the electromotive series of metals. Suitable fillers which can be incorporated include organic materials such as wood, flour, cork, cotton linters and organic fabrics, or inorganic materials, such as glass, CaCO 3 , asbestos, crushed quartz, titania, ZnO and SiO 2 powder. Fume silicas, silica aerogels and precipitated silicas of high surface area are preferred as reinforcing fillers. Hollow glass microspheres as filler gives a low density material. Other additives include pigments, sunscreen agents, oxidation inhibitors and dielectric materials, e.g. graphite and carbon black. Uses.-The compositions which cure spontaneously at room temperature upon mixing (a), (b) and (c) can be used as a sealant, e.g. in aircraft fuel tanks, or for encapsulating electronic components.