GB544143A - Aryl silicone condensation products - Google Patents

Abstract

544,143. Silicones ; synthetic resins. BRITISH THOMSON-HOUSTON CO., Ltd. Sept. 25, 1940, No. 14533. Convention date, Sept. 27, 1939. [Class 2 (iii)] [Also in Group YIII] Resinous polymeric aryl silicones of the R general formula R<SP>1</SP> > SiO, in which either or both R and R<SP>1</SP> are halogenated aryl radicals and either may be alkyl, aryl or aralkyl; are produced by hydrolysing an halogenated aryl silicon dihalide and condensing the hydrolysed product by heating ; further condensation may be effected at elevated temperature. Flame-proof products of good electrical properties are obtained. The initial condensates may be dissolved in a volatile solvent and employed as coating and impregnating compositions, e.g. for plain or wrapped conductors, woven or felted fabrics, as a binder for flaky materials, e.g. mica or for treating coherent films of clay, e.g. bentonite with which may be associated glass &c. fibres ; the fully condensed products may be associated with inorganic fibres and fillers, e.g. asbestos, mica, glass, to produce heat-resistant insulating materials. Mixtures of different halogenated aryl silicones may be employed and may be produced from mixed silicones condensed together, from a mixture of silicones advanced separately to an intermediate stage, or by mixing and grinding together fully condensed individual silicones. The silicones, simple or mixed, may be compounded with flammable materials, e.g. rubber ; tars, asphaltes and pitches ; natural and synthetic resins, and cellulose and cellulose derivatives ; they may also be compounded with plasticizers &c., e.g. dibutyl phthalate, tricresyl phosphate, chlorinated diphenyls, ethyl silicate. Cotton, wool, linen, wood &c. may be flame-proofed with the silicones which may also be used as protective coverings for glass, as semi-conducting paints and as sealing compositions for uniting glass to metal. Coating compositions may be obtained. by dissolving or dispersing initial products in drying oils, alone or mixed with solvents, pigments, plasticizers, driers &c. Laminated products and moulding compositions are also referred to. Specified halogenated silicones are the di-trichlorophenyl, dibromophenyl, methyl trichlorophenyl and dichlorotolyl silicones. Halogenated silicones derived from other aryl derivatives include those from halogen derivatives of toluene, xylenes, mono-, di- and tri-ethyl benzenes, diphenyl, diphenylene oxide, diphenyl ether, naphthalene, methyl naphthalene, tetrahydronaphthalene, indene and anthracene. In an example, (1) di-phenyl silicon dichloride is treated with chlorine at 70-120‹ C. in the presence of a catalyst until 2-10 and preferably 6-10 grain atoms of chlorine have been introduced, the chlorinated product is purified by distillation under diminished pressure and the product is hydrolysed by pouring into water and boiling, after which the flocculent silicol is separated, washed and converted to silicone by heating at 125-150‹ C. until it becomes a clear liquid which, by further heating at 175-250‹ C. is converted to a resinous product, (3) methyl phenyl silicon dichloride is similarly chlorinated and worked up, (2) di-p-fluorphenyl silicon dichloride is hydrolysed and further worked up and (4) di-pnenyl silicon dichloride is heated with iodine and iodic anhydride to form di-iodophenyl silicon dichloride which is then hydrolysed and worked up. Di-phenyl silicon dichloride is obtained by adding 1 mol of silicon tetrachlorid to an ether solution of 2“ mols. of phenyl magnesium bromide, with rapid stirring ; after filtering from magnesium salts and evaporation of the ether, the dichloride is separated from phenyl silicon trichloride and triphenyl silicon chloride by distillation under diminished pressure. Di-p-fluorphenyl silicon dichloride is similarly prepared from p-fluorphenyl magnesium bromide (obtained by the action of magnesium on p-fluorbromobenzene).