Patent GB-1072298-A (GB)
Title: Process for the preparation of dibasic lead salts
IPC: C08K3/11
Filed: 1964-10-09
Abstract: Dibasic lead salts of inorganic acids may be used as colour pigments. The dibasic lead salts, which are of the general formula 2PbO.Pb(R)n, where R is an inorganic acid radical of valency 2/n, are prepared by reacting aqueous solutions of dibasic lead salts of aliphatic carboxylic acids having up to 6 carbon atoms with aqueous solutions of salts of inorganic acids, for example alkali metal salts.  The dibasic lead salt of an aliphatic carboxylic acid may be prepared in an aqueous phase reaction between lead monoxide and the acid, for example acetic acid. Dibasic lead phosphite, sulphate, carbonate or silicate may be prepared from a solution of dibasic lead acetate and a solution of sodium phosphite, sodium sulphate, alkali metal carbonate or alkali metal silicate, respectively.  The solution of alkali metal carbonate, for example sodium carbonate, preferably also contains bicarbonate; the solution of alkali metal silicate may be a sodium silicate, for example waterglass, solution which gives dibasic lead metasilicate or orthosilicate according to the relative proportions of the reactant solutions.ALSO:Dibasic lead salts of inorganic acids, of the general formula 2PbO.Pb(R)n where R is an inorganic acid radical of valency 2/n , are prepared by reacting aqueous solutions of dibasic lead salts of aliphatic carboxylic acids having 1 to 6 carbon atoms with aqueous solutions of salts of inorganic acids, for example alkali metal salts.  The solution of the dibasic lead salt of the aliphatic carboxylic acid may be prepared in an aqueous phase reaction between lead monoxide and the carboxylic acid with a molar ratio of lead monoxide to carboxylic acid of 3 : 2, the resulting clear or colloidal solution being freed from water-insoluble impurities by filtration.  The lead monoxide may be only of commercial purity; the preferred carboxylic acid is acetic acid, but formic, propionic, butyric, valeric or caproic acid may be used. Dibasic lead phosphite, sulphate, carbonate or silicate may be prepared from a solution of dibasic lead acetate and a solution of sodium phosphite, sodium sulphate, alkali metal carbonate or alkali metal silicate, respectively. The solution of alkali metal carbonate, for example sodium carbonate, preferably also contains bicarbonate; either the solution initially contains both carbonate and bicarbonate or the pH of the carbonate solution is adjusted to about 7 by dilute acids.  The solution of alkali metal silicate may be a sodium silicate, for example waterglass, solution which gives dibasic lead metasilicate, 2PbO.PbSiO3. 2H2O, or dibasic lead orthosilicate, 4PbO. Pb2SiO4.4H2O, according to the composition of the sodium silicate and/or the relative proportions of the reactant solutions.ALSO:Dibasic lead salts of inorganic acids may be used as heat and light stabilizers in the working up of halogen-containing polymers such as polyvinyl chloride.  The dibasic lead salts, which are of the general formula 2PbO.Pb(R)n where R is an inorganic acid radical of valency 2/n , are prepared by reacting aqueous solutions of dibasic lead salts of aliphatic carboxylic acids with aqueous solutions of salts of inorganic acids.  Dibasic lead phosphite, sulphate, carbonate or silicate so prepared is added to PVC together with dioctyl phthalate and lubricating wax.