Latex de caoutchouc de silicone

摘要

1,127,152. A silicone latex. DOW CORNING CORP. 12 Jan., 1966 [21 Jan., 1965; 7 Sept., 1965], No. 1489/66. Heading C3T. A silicone latex comprises an aqueous colloidal suspension of (1) a curable linear polysiloxane having at least 10 units per molecule, and (2) a silsesquioxane of unit formula R11SiO 3/2 , where R11 is a methyl, ethyl, vinyl, phenyl or 3,3,3- trifluoropropyl radical, and having a particle size in the range of 10 to 1000 Š. Suitable polymers (1) are polysiloxanes or siloxane-silcarbane polymers having terminal Si-bonded OH or hydrocarbonoxy radicals, those which have been made by emulsion polymerization being preferred. The latex may also contain a cross-linking agent, e.g. a methylhydrogensiloxane or a silane of the formula wherein A is H or a monovalent hydrocarbon (h.c.) radical of 1-6 C atoms, with or without halogen substituents, m is 0 or 1, and R111 is H, an alkyl radical of 1-4 C atoms, -OCOCH 3 , -OCOC 2 H 5 , -CH 2 CH 2 OH, -CH 2 CH 2 OCH 3 or -CH 2 .CH 2 OC 2 H 5 , and a condensation catalyst which can be added as a solution, emulsion or undiluted liquid. Pigments, fillers, heat stabilizers and other additives may also be added. Usually 100 pts. (by wt.) of polymer (1), 1-100 pts. of polymer (2), 0À25 to 50 pts. of crosslinking agent and 0À25 to 5 pts. of catalyst are used for making the latices which preferably contain a total solids content of 5 to 20% by wt. The latices are made by first making a colloidal suspension of polymer (1), if not already in this form; the dispersing agent can be added per se or it can be the one used and present in the emulsion polymer or colloidal silsesquioxane, the silsesquioxane, cross-linker, catalyst and additives are then mixed with the suspension of polymer (1) to form the latex. The latices are stable on standing, but when applied to a substrate and the water evaporated, a film of silicone rubber or plastic is left behind, and curing by heat or irradiation will be necessary in some instances. Examples of the above latices are given. Uses.-For depositing insulating coatings on wires, coatings on medical devices, release coatings on papers, metals and moulds, coatings on fabrics, and protective and decorative coatings on wood, metal and concrete.