GB797543A - Improvements in or relating to alkaline earth metal silicates - Google Patents

Abstract

Finely-divided alkaline-earth metal silicate, particularly calcium, preponderantly in the form of fine non-crystalline flakes ranging up to at least ten microns across a long dimension with a thickness ranging from about 100 <\>r. to 800 <\>r. and having a ratio of alkaline earth metal oxide to silicon dioxide between 1 and 5, is prepared by reacting an aqueous solution of <PICT:0797543/III/1> an alkaline earth metal salt with an aqueous solution of an alkali metal silicate while subjecting the reactants to an intense agitation and correlating the concentration of the alkali metal silicate reactant and the final concentration of the un-reacted alkaline earth metal salt in the reaction product mixture to agree stoichiometrically with the respective concentration of alkaline metal silicate and calcium chloride within the area to the right of the curve AB of the Figure, particularly to the right of curve CD of the Figure. This is to maintain the concentration of unreacted alkaline earth metal salt in the reactant/product mixture. Reference has been directed by the Comptroller to Specification 743,930.ALSO:<PICT:0797543/IV (a)/1> Finely-divided alkaline earth metal silicate, particularly calcium, preponderantly in the form of fine non-crystalline flakes ranging up to at least ten microns across a long dimension with a thickness ranging from about 100 . to 800 . and having a ratio of alkaline earth metal oxide silicon dioxide between 1 and 5 is particularly suitable as a rubber pigment particularly for the synthetic rubber such as butadiene, butadiene-styrene copolymers known as GR-S rubber, i.e. 10 to 60 per cent by weight of styrene and 90 to 40 per cent by weight of butadiene; butadiene-acrylonitrile copolymers of 40 to 90 per cent butadiene and 60 to 10 per cent of acrylonitrile; neoprene rubber; isobutylene polymers and copolymers of isobutylene with 0.01 to 4.0 per cent of isoprene (based upon the weight of isobutylene) or other elastomers prepared by polymerization of butadiene-1,3-1,3, isoprene, piperylene, 2,3-dimethyl butadiene or 2-chlorobutadiene-1,3 alone or in admixture with one or more organic, monomeric or ethylenic compounds including acrylonitrile, isobutylene, vinyl chloride, vinyl acetate, styrene, methyl methacrylate, methyl alphachloroacrylate and methyl acrylate. Other silicates such as magnesium, barium or strontium may be used in lieu of all or part of the calcium salt. Reference has been directed by the Comptroller to Specification 743,930.