GB1035876A - Paper sizing - Google Patents

Abstract

Emulsions of organopolysiloxanes, for use in sizing paper (see Division D2), are made as follows: (A) a 94/6 mixture of methylhydrogendichlorosilan and trimethylmonochlorosilane is hydrolysed to give an oil of 20 cS viscosity, octamethyl-cyclotetrasiloxane is treated with bleaching earth and heated at 120 DEG C. to a viscosity of 1000 cS, then two oils are mixed in equal amounts and emulsified in water with cetylbenzyldimethyl-ammonium chloride, glycocoll and hydrochloric acid; (B) a 90/10 mixture of methylhydrogendichlorosilane and trimethylchlorosilane is hydrolysed to a thinly liquid oil, which is emulsified in water with dodecylamine, tetrabromoethane, aminocaproic acid and hydrochloric acid; (C) 9 parts of methyltrichlorosilane, 1 part of dimethyldichlorosilane, 8 parts of toluene and 2 parts of n-butanol are added to a mixture of 40 parts of water and 20 parts of toluene, a silicone-resin solution is obtained by hydrolysis and subsequent neutralization with sodium bicarbonate, solvent is distilled off to 50% solids, 36 parts of the silicone oil B are mixed with 8 parts of this solution and emulsified in water with cetylbenzyldimethylammonium chloride, glutamic acid and hydrochloric acid; (D) a mixture of 60.4 parts of methylhydrogendichlorosilane, 34.6 parts of dimethyldichlorosilane and 5 parts of trimethylmonochlorosilane is hydrolysed to a thin oil, which is emulsified in water with cetylbenzyldimethylammonium chloride, hydrochloric acid and aminopropionic acid; and (E) an equimolar mixture of methyltrichlorosilane, dimethyldichlorosilane, phenyltrichlorosilane and diphenyldichlorosilane is hydrolysed in a mixture of water, butanol and cyclohexanol, the product washed with water and concentrated to 50% by distilling off solvent, 38 parts of silicone oil B are mixed with 4 parts of this resin solution and emulsified in water with dodecylamine, tetrabromoethane, glycocoll and hydrochloric acid.ALSO:Paper is sized by adding to the pulp an aqueous emulsion of linear organopolysiloxane in which the end units are R2 (OH)SiO 1/2 , (CH3)2 (H)SiO 1/2 or (CH3)3SiO 1/2 , 50 to 100% of the siloxane units are R(H)SiO, and all remaining units are R2SiO, in which formulae each R is alkyl or aryl, in amount equivalent of 0.01 to 5 parts of organosiloxane by weight per hundred parts of air-dried cellulose pulp. The linear organopolysiloxane may be mixed with up to 10% by weight of a cross-linked or branched organopolysiloxane of units RSiO 3/2 and R2SiO. The emulsifier in the emulsion may be of the cation-active type. The emulsion may also contain a metal salt, e.g. dibutyltin dilaurate, dioctyltin dimaleate or compounds of lead, cobalt, zinc, titanium or cerium, to accelerate cure or a watersoluble prepolymer of a synthetic resin, e.g. polyethyleneimine, urea-formaldehyde, melamineformaldehyde, ethyleneurea-formaldehyde, N-alkylurea-formaldehyde, guaridine-formaldehyde, dicyandiamide-formaldehyde, epoxide resin or a product of reaction of a polyamine with epichlorohydrin, dichlorohydrin or an epoxide resin. Fillers may be incorporated in the pulp, e.g. kaolin, calcium silicate, calcium sulphate, barium sulphate, talc, chalk, titanium dioxide, zinc sulphide or amorphous silica.