Emulsion copolymerization of styrene with bodied oil or bodied oil modified alkyd

摘要

Bodied linseed oil or dehydrated castor oil or an alkyd resin modified with either or both, or an oleo-resinous varnish containing one or both, together with styrene or methyl methacrylate are suspended in an aqueous medium and copolymerized by heating, preferably at a pH above 7.5, to 55-60 DEG C. in the presence or absence of light and/or of a polymerization catalyst, e.g. hydrogen peroxide, ammonium persulphate and sodium perborate. Polymerization may be stopped at the desired point by addition of phenolic or aromatic amine compounds. A suitable alkyd resin is made by heating together at 250 DEG C. under an atmosphere of carbon dioxide, phthalic anhydride, glycerol and castor oil until the acid number had fallen to 8. A suitable varnish is made by heating together at 270 DEG C. dehydrated castor oil and the pentaerythritol ester of rosin. Rosin, dispersing agents, e.g. sodium oleate, sodium dinaphthylmethane sulphonate, the sodium salt of castor oil or of a mixture of sulphated olefins, stabilizers, e.g. ammonium caseinate, dextrose and gelatine, pigments, e.g. titanium dioxide and iron oxide, driers, e.g. lead, cobalt and manganese naphthenates, modifying agents, synthetic resins, organic solvents and oils may be added. Instead of mixing pigment and drier into the emulsion, the pigment may be formed into a paste with water, which may contain a wetting agent or stabilizer, and then mixed with the emulsion. Specifications 573,809, 573,835, 580,912, 580,913 and 609,750 are referred to.