Imperial Chemical Industries Limited

Dulux Australia Ltd.

Clive W Graetz

Morice W Thompson

Charles W Bromley

A crosslinkable coating composition is described which is miscible in all proportions with water and consists of crosslinked water-insoluble polymer microparticles sterically stabilised in dispersion in a liquid blend of a water-soluble crosslinking agent and a water-soluble, non-volatile substance of molecular weight less than 1000 which can take part in the crosslinking reaction but does not dissolve or swell the polymer, the amounts of the crosslinking agent and of the water-soluble non-volatile substance being up to 30% and 40% respectively of the total weight of film-forming material.

Coating compositions

Sterically stabilized aqueous polymer dispersions of at least 20% solids content are made by free radical-initiated polymerization of monomers in an aqueous medium at a temperature at least 10.degree. C. higher than the glass transition temperature of the polymer to be formed, in the presence of a compound which is soluble in the aqueous medium and contains in the molecule a polymeric component of molecular weight at least 1000 which is solvatable by the aqueous medium and an unsaturated grouping which can copolymerize with the monomers, the conditions being such that there is at no time present a separate monomer phase. The dispersions are useful as a basis of improved coating compositions.

Manufacture of aqueous polymer dispersions and coating compositions

Macromonomers are obtained by successively reacting an oligomer or polymer containing at least one hydroxyl group with a cyclic carboxylic anhydride in an amount of at least one mole of the anhydride per hydroxyl group, and reacting the product with a compound containing a single epoxide group and a single polymerizable double bond, in such proportions as to esterify all carboxyl groups in that product. Graft copolymers which are useful as steric stabilizers for dispersions of polymer particles can be made by copolymerizing the macromonomers with other polymerizable monomers.

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Glen Waverly, Australia

Clive W Graetz