Imperial Chemical Industries Limited

The Glidden Company

Dulux Australia Ltd.

Charles W Bromley

Morice W Thompson

Alan J Backhouse

Norman A Coombes

Philip Louis Taylor

Peter F Nicks

Brian A Cooke

Jonathan A Graystone

Clive W Graetz

Michael R Wilkinson

Julian J Gosling

A water-based autoxidizable coating composition, especially a gloss or partial gloss coating composition (e.g. paint, varnish, woodstain or timber preservative) suitable for application at ambient temperatures which comprises water, preferably organic cosolvent and a partially esterified carboxylic acid film-forming copolymer at least partially neutralized by monovalent cations wherein the copolymer contains added 3-allyloxy-2-hydroxypropyl groups or certain analogues derived from addition of allyl glycidyl ether or certain of its analogues to carboxylic acid groups, in a copolymeric backbone portion derivable from a prepolymer of weight average molecular weight less than 30 000. The partially esterified copolymer has an acid value of 25 to 60 and preferably a dynamic solution viscosity of 1 to 500 Pa.sec measured in 1-methoxy-2-hydroxy propane by oscillatory parallel plate rheometer. The coatings lap well, dry quickly and achieve acceptable water resistance. Also the optionally unneutralized copolymer and the coating composition when containing a minor amount of particulate copolymer which is found to improve gloss. Discoloration on ageing may be improved by neutralizing with Group 1 metal cations.

Water-based autoxidisable coating composition

A coating composition which is especially suitable for producing decorative coatings upon wood substrates comprises, as at least 51% by weight of the film-forming material present, a sterically stabilized dispersion in a volatile organic liquid of insoluble vinyl or acrylic polymer particles, the polymer having an extensibility of 50-2000% and being crosslinked to such an extent that it has a gel content of at least 35% by weight.

Coating compositions

Aqueous compositions suitable for forming on a substrate a temporary protective coating, which can subsequently be removed by treatment with an aqueous alkaline solution, comprise a sterically stabilized dispersion in an aqueous medium of particles of size range 0.1-10 .mu.m of a polymer derived from monomers including at least one acrylic monomer and from 5% to 40%, based on the total weight of monomers, of an ethylenically unsaturated monocarboxylic acid, or an equivalent proportion of an unsaturated polycarboxylic acid.

A washcoat composition suitable for application to tin-plated mild steel consists of an aqueous carrier medium and a binder comprising specified relative proportions of (A) a thermosetting acrylic polymer in the form of a sterically stabilized dispersion in the aqueous medium and (B) an epoxy resin, the composition additionally containing an acid catalyst, in particular phosphoric acid or chromic acid or an ammonium or amine salt thereof.

A process is described for making sterically stabilized non-aqueous dispersions of composite polymer microparticles, in which (1) monomers including at least one crosslinking monomer are polymerized in an aqueous medium at a temperature at least 10.degree. higher than the glass transition temperature of the polymer to be formed, in the presence of a block or graft copolymer stabilizing agent, under conditions such that there is at no time present a separate monomer phase, (2) further monomers, not including any crosslinking monomer, are polymerized in the dispersion thus obtained, the presence of a separate monomer phase again being avoided, and (3) the microparticles are transferred from the resulting dispersion into a non-aqueous medium which is a solvent for the non-crosslinked polymer generated in (2). The microparticles are of value for incorporation into coating compositions the main film-forming constituent of which is compatible with the non-crosslinked component of the particles.

Polymerization process

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.

A process is described for making sterically stabilized non-aqueous dispersions of polymer microparticles, in which (1) monomers including at least one crosslinking monomer are polymerized in an aqueous medium at a temperature at least 10.degree. higher than the glass transition temperature of the polymer to be formed, in the presence of a block or graft copolymer stabilizing agent containing in the molecule, as the component solvated by the aqueous medium, a polymer chain derived from a polyethylene glycol of molecular weight at least 1000, under conditions such that there is at no time present a separate monomer phase and (2) the microparticles thus obtained are transferred into a non-aqueous medium which is capable of dissolving the polyethylene glycol in question, when the latter is in the non-hydrated state, to the extent of at least 10% by weight at room temperature. The microparticles are of value for incorporation into coating compositions the main film-forming constituent of which is compatible with the polyethylene glycol-derived stabilizing chains of the particles.

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Bourne End, United Kingdom

Charles W Bromley