Patent GB-682348-A (GB)
Title: Improvements in or relating to coating compositions
IPC: C09D167/08
Filed: 1950-07-12
Abstract: A coating composition comprises an aromatic solvent solution of a cobodied inter-reaction product of (a) between 25 and 90 per cent by weight of a monocarboxylic acid modified alkyd having an acid number below 50 resulting from the reaction of at least one polybasic acid which boils or sublimes above 200 DEG  C., at least one of the polyhydric alcohols glycerol, pentaerythritol, trimethylol propane and trimethylol ethane and at least one saturated monocarboxylic acid, having from 6 to 10 carbon atoms and/or aryl or alkaryl monocarboxylic acid having 6 to 11 carbon atoms in amount to give an oil length between 35 and 50 per cent, and (b) between 75 and 10 per cent by weight of an aromatic hydrocarbon soluble polysiloxanol having Si-O-Si linkages, the remaining valencies of the Si atoms being satisfied with methyl, phenyl and hydroxyl radicals of which 10 to 90 per cent of the methyl and phenyl radicals are phenyl radicals and the average number of methyl and phenyl radicals per Si atom is between 1 and 1.7, the hydroxy content being between 0.45 per cent and 20 per cent by weight of the polysiloxanol.  The inter-reaction product is made by co-bodying in solution in an aromatic hydrocarbon the alkyd and polysiloxane under reflux conditions with removal of water in the aromatic solvent until an increase in viscosity short of gelation has been secured.  The alkyds used have the ability, when co-bodied with the polysiloxanols, to volatilize at elevated temperatures, e.g. 500 DEG  F., and those disclosed are derived from phthalic acid or anhydride, the specified polyhydric alcohols to which may be added small quantities of glycols, and one or more of the acids: 2-ethyl hexoic, nonanoic, p-tertiary butyl benzoic and benzoic, as described in U.S.A. Specification 2,437,657.  The polysiloxanols disclosed are the hydrolysis and partial condensation products of mixtures of silanes from silicon tetrachloride, phenyltrichloro-, methyltrichloro-, diphenyldichloro-, phenylmethyldichloro-, dimethyldichloro-, triphenylchloro-, diphenylmethylchloro-, phenyldimethylchloro- and trimethylchloro - silanes.  Aromatic solvents specified are xylol and toluol.  The co-bodied mass may be thinned with additional solvent and applied as a coating composition with or without addition of pigments such as titania (anatase and rutile), cadmium yellow, red or orange, phthalocyanine blue, carbon black, aluminium and du Pont's fast violet, and extenders such as barium sulphate, mica, and asbestine. In example (1) a xylol solution of an alkyd, derived from 2-ethylhexoic acid, glycerine and phthalic acid, was co-bodied with a xylol solution of a polysiloxanol derived from equimolar quantites of phenyl-trichloro-, methyltrichloro-, and phenylmethyldichloro-silanes, and the resulting clear varnish was pigmented with titania and cobalt napthenate added to form an enamel. Further examples of similar varnishes and enamels are given, some of which include the addition of butanol prior to further dilution with xylol.  The varnishes may be used for base metal sanitary ware, electric wires and glass fibre insulation and the enamels for coating metal and glass panels.  Specifications 583,754 and 650,247 are referred to.