IMPREGNATING AGENTS FOR RENDERING BUILDING MATERIALS WATER-REPELLENT

摘要

1,246,685. Water-proofing building materials. WACKER-CHEMIE G.m.b.H. 1 Nov., 1968 [3 Nov., 1967], No. 51965/68. Heading D1P. [Also in Division C3] Building materials are rendered water-repellent by applying thereto an impregnating agent comprising a solution in an organic solvent of a methylpolysiloxane and 2-100 wt. % based on the polysiloxane of polymethyl methacrylate and/or copolymer of vinyl chloride which is soluble in the organic solvent. Preferably the polysiloxane has the general unit formula in which each R is H or a C1-4 alkyl radical, x and y are each 0, 1, 2 or 3, the sum of x+y not exceeding 3 and the average value of x being 0.9-1.7 and of y being 0.01-0.20; more preferably not more than 30 mol % of the siloxane units have more than one Sibound methyl radical; the viscosity is preferably below 1000 cSt/25‹C in 50 wt. % toluene solution. Suitable vinyl chloride copolymers are those with vinylidene chloride, vinyl esters of saturated aliphatic or cycloaliphatic monocarboxylic acids, acrylic acid, alkyl esters of unsaturated monocarboxylic acids (e.g. methyl acrylate), acrylonitrile, aliphatic unsaturated dicarboxylic acids (e.g. maleic acid or anhydride, or itaconic acid) and mono- and di-alkyl esters thereof, and vinyl ethers (e.g. vinyl isobutyl ether). Preferred copolymers contain 50-95 wt. % of vinyl chloride, the remaining units being of vinyl acetate; particularly preferred are those containing an addition 5-15 wt. % of maleic or itaconic acid, relative to the vinyl acetate. Suitable solvents include alkanes of b.p. 120-180‹C, toluene, xylene, trimethylbenzenes, trichlorethylene, diacetone alcohol, isopropanol, methyl ethyl ketone, and ethyl and butyl acetates. The polysiloxanecopolymer mixture preferably amounts to 0.5-20 wt. % of the solution. Curing catalysts, e.g. Zn octoate, or Ti or Al alcoholates, may be added. In Examples a polysiloxane of average unit formula (CH 3 ) 1 . 10 Si(OC 2 H 5 ) 0À02 (OH) 0 . 04 O 1À42 is mixed with polymethyl methacrylate or an 84/15/1 (% wt.) copolymer of vinyl chloride/vinyl acetate/maleic acid in toluene/ethyl acetate, and the solutions are used to impregnate tiles of building gypsum or concrete.