Pigmented basecoat composition
AssigneeImperial Chemical Industries PLC
InventorAlan J. Backhouse
Life of this patent
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Abstract
For use in a process for producing a multi-layer coating upon a substrate surface, in which there is first applied to the surface a pigmented basecoat composition and there is then applied to the basecoat film a transparent topcoat composition, a pigmented basecoat composition which is based upon a dispersion in an aqueous medium of crosslinked polymer microparticles which have a diameter of 0.01-10 microns, are insoluble in the aqueous medium and are stable towards gross flocculation, the dispersion having a pseudoplastic or thixotropic character.
Claims9
A basecoat composition suitable for use in a process for the production of a multi-layer protective and/or decorative coating upon a substrate surface, which process comprises the steps of:
- (1) applying to the surface a basecoat composition;
- (2) forming a polymer film upon the surface from the composition applied in step (1);
- (3) applying to the basecoat film so obtained a transparent topcoat composition comprising (d) a film-forming polymer, and (e) a volatile carrier liquid for the said polymer;
- (4) forming a second polymer film upon the basecoat film from the composition applied in step (3);
- and
- (5) curing the polymer film from steps (2) and (4), said basecoat composition comprising:
- (a) a film-forming material,
- (b) a volatile liquid medium for said material, and
- (c) pigment particles dispersed in said medium;
- characterised in that constituents (a) and (b) of the basecoat composition are provided by a pseudoplastic or thixotropic dispersion in an aqueous medium of crosslinked polymer microparticles which have a diameter in the range of about 0.01 to about 10 microns, are insoluble in the same aqueous medium and are stable towards gross flocculation, the dispersion having been produced by the steps of:
- (I) polymerising in an aqueous medium in thepresence of a stabiliser a first mixture of ethylenically unsaturated monomers consisting of:
- (i) 98.5-90% by weight of monomers which contain in the molecule a single polymerisable unsaturated grouping, and
- (ii) 1.5-10% by weight of monomers which contain in the molecule at least two polymerisable unsaturated groupings, so as to produce a dispersion of particles of crosslinked polymer;
- (II) polymerising in the same medium and in the presence of the said crosslinked particles a second mixture of ethylenically unsaturated monomers consisting of:
- (iii) 2-30% by weight of an unsaturated carboxylic acid,
- (iv) 0-30% by weight of a hydroxyl group-containing monomer, and
- (v) 40-98 parts by weight of one or more other monomers different from those of (iii) or (iv), so as to produce a non-crosslinked polymer which is capable of forming a water-soluble salt derivative, the crosslinked polymer constituting 40-95% by weight of the total polymer of steps (I) and (II), and
- (III) subsequently forming the said salt derivative by neutralising the carboxyl groups present in the non-crosslinked polymer with an inorganic or organic base in the presence of the same aqueous medium.
Dependencies are inferred from the claim text.