Pasten auf Grundlage von Organopolysiloxanoelen und Fuellstoffen

摘要

1,183,512. Silicone greases. DOW CORNING CORP. 11 April, 1967 [14 April, 1966], No. 16581/67. Heading C3T. [Also in Divisions C1 and C5] A grease comprises, by wt., (a) 100 pts. of a liquid siloxane of the average general formula R n SIO 4-n/2, wherein each R is a monovalent hydrocarbon (h.c.) or halo-aryl radical containing not more than 7 C atoms and free from aliphatic unsaturation, and n has an average value of 1.9 to 2À1, the viscosity of (a) being from 20 to 30,000 cs. at 25‹ C., (b) 5 to 25 pts. of a powdered SiO 2 filler having a surface area of at least 100 m2/g., which filler is rendered hydrophobic by treatment with (c) 2 to 150% (by wt. of (b)) of a silicon compound which is (1) a silazane of the formula (R1 3 Si) a NH 3-a , where a is 1 or 2 and R1 is a monovalent h.c. or halo-h.c. radical of not more than 7 C atoms, (2) a polysilazane of the unit formula (-R1 2 SiNH-) which has a viscosity of not more than 200 cs. at 25‹ C., or (3) a silane of the formula R1 b SiX 4-b , where X is -Cl, -Br, -OH or a lower alkoxy or acyloxy radical and b is 2 or 3, and (d) 5-100% (by wt. of (b)) of a liquid-hydroxylated organopolysiloxane containing 1À8 to 2À1 R1 radicals per Si atom and having a Si-bonded -OH content of at least 1% by wt. Ingredients (a), (b), (c) and (d) can in themselves be mixtures, if desired. Preferably (a) is a dimethylpolysiloxane, (c) is hexamethyldisilazane and (d) is a hydroxylated phenylmethylsiloxane liquid. When (c) is a silanol or alkoxysilane, a condensation catalyst e.g. dibutyltindilaurate, tetrabutyltitanate, stannous octoate or guanidine octoate, should be added to the grease while mixing, with subsequent heat treatment. The ingredients may be mixed together in a volatile organic solvent. Corrosion and oxidation inhibitors, dyes and bleed-reducing agents, may also be added. In a typical Example (1)(a) powdered SiO 2 , an organic solvent, a mixture of a liquid phenylmethylsiloxane and sym - trimethyltripheriylcyclotrisiloxane, and hexamethyldisilazane, were mixed together and heated at 150‹ C. with agitation for hr. under vacuum to yield a hydrophobic silica, to which were then added a dimethyl-, phenylmethyl-siloxane copolymer, another portion of the above siloxane mixture, a purple dye in a liquid siloxane and a corrosion inhibitor; the resulting mixture was milled to form a grease.