| 摘要 |
A homogeneous solution obtained by hydrolysing one or more alkoxysilanes with water in the presence of an organic ortho- or polytitanate, or hydrolysis catalyst (see Division C3) is used, after the addition of conventional curing catalysts, for impregnating fillers as by dipping, spraying, brushing or roller coating. In a modification, the siloxanes are formed in situ by contacting the fillers with a mixture of the silane and titanate and then with water. The fillers (in sheet, fibrous or particulate form) can be asbestos fibres, diatomaceous earth, tale, glass fibres or powder, flake or integrated mica, Al2O3, TiO2, MgO, Fe2O3, ZnO, crushe quartz, various silicas or C black. The impregnated fillers can then be heated to cure the siloxane and consolidate the filler and can subsequently be moulded. In Example 26, Al2O3 was dipped into a mixture of phenyltrimethoxysilane, methyltrimethoxysilane and tetraisopropyl titanate, and then dipped into water to form a slurry and the slurry shaped into a disc which was air dried and subsequently moulded under pressure at 150 DEG C. for 4 hours.ALSO:A homogeneous solution is obtained by mixing (1) one or more silanes of the formula RnSi (OR1)4-n in which each R is a phenyl radical or an alkyl or alkenyl radical of less than 4 C atoms, each R1 is an alkyl group of less than 4 C atoms and n is 0,1,2 or 3 and has an average value of from 0.9 to 1.9, (2) at least 0.5 mole of water per mole of silane [OR1] radicals, and (3) a catalyst which is an orthotitanate of the formula Ti-(OR11)4, or a partial condensate thereof, in which R11 is a hydrocarbon of 1 to 30 C atoms with or without nitrogen or oxygen atoms in certain forms, the catalyst being present in amount to provide 0.0001 to 0.012 atom of Ti per atom of Si. Numerous examples of hydrolysis catalysts (3) are given. A curing catalyst can be mixed with the silane, water and titanate to enhance the curing of the hydrolysis product; suitable curing catalysts are those disclosed in Specification 848,373 and metal carboxylates, amines and quaternary ammonium compounds. The products are used for impregnating fillers, as by dipping, spraying, brushing, or roller coating. In a modification the siloxanes are formed in situ by contacting the fillers with a mixture of the silane and titanate and then with water. The fillers, in sheet, fibrous or particulate form, can be metals, asbestos fibres or cloth, diatomaceous earth, talc, glass powder fibres or cloth, flake and integrated mica, Al2O3, TiO2, MgO, Fe2O3, ZnO, crushed quartz, silicas, C black, paper, nylon or polyester fibres. The impregnated fillers can then be heated and subsequently moulded or formed into laminates. Examples are given. |
