Patent GB-746038-A (GB)
Title: Stable aqueous vinylsilanol dispersions
IPC: C07F7/08
Filed: 1953-03-23
Abstract: Stable aqueous dispersions of vinyl silanols are prepared by neutralizing to a pH between 3 and 8 an aqueous solution of an alkali or alkaline earth metal salt of a vinylsiloxanate having from 0.05 to 1 vinyl group per silicon atom and from 0.05 to 3 total organic groups per silicon atom, the organic groups, other than vinyl, being mono- or divalent aliphatic hydrocarbon having from one to five carbon atoms, or mono-or divalent aryl groups having six or seven carbon atoms.  The siloxanates may be obtained by hydrolysing the corresponding hydrolysable silanes with caustic alkali or by dissolving the corresponding siloxanes in caustic alkali.  A long list of suitable silanes and hydrlysable groups is given. Neutralizing must be carried out rapidly to avoid condensation and consequent precipitation of polymers.  The dispersions are useful for applying to surfaces and porous materials to impart water resistance. In examples (1) vinyltriethoxysilane is hydrolysed in aqueous caustic soda containing ethanol, the ethanol is distilled off and the siloxanate cooled to 10 DEG  C. and neutralized by adding hydrochloric acid with stirring, over a period of 5 minutes.  The silanol dispersion is used to waterproof glass fibres, the result being favourably compared with treatment of the fibres with a siloxanate solution followed by acidification on the fibre.  (2) The silanol dispersion of example (1) is used to waterproof glass bottles.  (3) Vinyltrichlorosilane is hydrolysed in concentrated hydrochloric acid and the precipitate dissolved in caustic soda. The siloxanate is neutralized as in example (1).  (4) Ethylvinyldichlorosilane is hydrolysed and the resulting siloxanate neutralized as in example (1).ALSO:Stable aqueous dispersions of vinyl silanols are prepared by neutralizing to a pH between 3 and 8 an aqueous solution of an alkali or alkaline earth metal salt of a vinyl siloxanate having from 0.05 to 1 vinyl groups per silicon atom and from 0.05 to 3 total organic groups per silicon atom, the organic groups other than vinyl, being mono- or di-valent aliphatic hydrocarbon having from one to five carbon atoms or monoor divalent aryl groups having six or seven carbon atoms.  The siloxanates may be obtained by hydrolysing the corresponding hydrolysable silanes with caustic alkali or by dissolving the corresponding siloxanes in caustic alkali.  A long list of suitable silanes and hydrolysable groups is given.  Neutralizing must be carried out rapidly to avoid condensation and consequent precipitation of polymers.  The dispersion are useful for applying to surfaces and porous materials to impart water-resistance.  In examples (1) vinyltriethoxysilane is hydrolysed in aqueous caustic soda containing ethanol, the ethanol is distilled off and the siloxanate cooled to 10 DEG  C. and neutralized by adding hydrochloric acid with stirring, over a period of 5 minutes.  The silanol dispersion is used to waterproof glass fibres, the result being favourably compared with treatment of the fibres with a siloxanate solution followed by acidification on the fibre. (2) The silanol dispersion of example (1) is used to waterproof glass bottles.  (3) Vinyltrichlorosilane is hydrolysed in concentrated hydrochloric acid and the precipitate dissolved in caustic soda. The siloxanate is neutralized as in example (1).  (4) Ethylvinyldichlorosilane is hydrolysed and the resulting siloxanate neutralized as in example (1).ALSO:Materials such as magnesium silicate, cellulose, porous ceramics, glass (bottles, fibres and cloth), non-carbonaceous masonry, sand, ores, wood products, paper clay, talc and mica (for use as mineral fillers in moulding compositions) and asbestos and related materials are made waterproof by the application, at a pH between 3 and 8, of a vinylsilanol aqueous dispersion (see Group IV(a)).  The material may be immersed in the dispersion or the dispersion applied to the material, followed by drying, whereupon the silanol condenses to form an insoluble water-repellant silicone.  The silanol may be applied in an amount of from 0.001 to 2 per cent by weight of the material.ALSO:Ores for flotation are made waterproof by the application, at a pH between 3 and 8, of a vinylsilanol aqueous dispersion (see Group IV(a)).  The material may be immersed in the dispersion or the dispersion applied to the material, followed by drying, whereupon the silanol condenses to form an insoluble water-repellant silicone.  The silanol may be applied in an amount of from 0,001 to 2 per cent by weight of the material.ALSO:Materials such as mica and asbestos and related materials are made waterproof by the application, at a pH between 3 and 8, of a vinylsilanol aqueous dispersion (see Group IV(a)).  The material may be immersed in the dispersion or the dispersion applied to the material, followed by drying, whereupon the silanol condenses to form an insoluble water-repellent silicone.  The silanol may be applied in an amount of from 0.001 to 2 per cent by weight of the material.