IMPROVED LOW TITANIUM DIOXIDE COATINGS

摘要

An aqueous coating composition having a PVC of from 78 to 85% comprising, based on the total volume solids of the dry coating unless otherwise stated,
a) opacifying pigment particles comprising
i) from 3 to 10% titanium dioxide
ii) from 0 to 20% of hollow polymeric particles
b) non-opacifying extender particles comprising
i) calcium magnesium carbonate and/or
ii) calcium carbonate and/or
iii) nepheline syenite and/or
iv) kaolin
wherein i)+ii)+iii)+iv) = 40 to 80% and iv) is 0 to 20%
c) polymer binder particles of calculated Fox Tg of from 5 to 25°C having an acid value of from 15 to 65mg KOH/g of polymer and wherein the polymer particles are derived from acrylic monomers and optionally further comprising styrene and/or its derivatives
d) dispersant having a weight average molecular weight of at least 3500 Daltons and selected on the basis that the dispersant demand of a mixture of the opacifying pigment particles, other than the hollow polymeric particles, of a) and the extender particles of b) is greater than 0.35wt%, calculated on the weight of the titanium dioxide and extender particles
e) fugitive coalescing solvent.