Sound, ground quartz or ground barytes are coated with an epoxide resin containing more than one epoxy group per molecule or with a resinous curing agent for the epoxide resin. In the examples:-(i) sand is coated with an aniline-formaldehyde resin by mixing at 100 DEG C. and (ii), and (iii) quartz is coated with an epoxide resin derived from diphenylolpropane and epichlolorydrin. Specification 906,639 is referredALSO:A method for the production of hardenable compositions comprising an inorganic particulate filler, an epoxide resin having on an average more than one epoxy group per molecule and a curing agent for the epoxy resin comprises (a) coating the filler particles with the epoxide resin and mixing the coated particles with the curing agent or (b) when the curing agent is a resinous compound, coating the filler particles with the resinous curing agent and mixing the coated particles with the epoxide resin or with a further amount of filler the particles of which have been previously coated with an epoxide resin. Specified fillers are sand, ground quartz or ground barytes. Specified epoxides are the reaction products of polyhydric phenols with epihalohydrins and epoxidized ethylenic compounds. The preferred curing agent is an aniline-formaldehyde resin. Solvents and/or diluents, e.g. toluene, methyl ethyl ketone, triphenyl phosphite, phenyl glycidyl ether and allyl glycidyl ether, additional fillers, e.g. chalk, slate flour and montmorillonite, plasticizers, e.g. polysulphide rubbers, dibutyl phthalate and tricresyl phosphate and vinyl resins, cellulose butyrate acetate, phenolic resins, dyes, pigments and accelerators, e.g. phenol, may be present in the reaction mixture. Two examples are given. Specification 906,639 is referred to.
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