Abstract: Marine anti-fouling compositions contain, in addition to the conventional resin, toxin, solvent, pigment and other additives, hollow particles, of size from 1 to 800 microns, in an amount to give a particle concentration in a dry paint film of 10 to 80% by volume. The hollow particles are preferably hollow microspheres or microballoons of glass or plastics material having an apparent bulk density of from 0.03 to 0.5 g/cc. The compositions can be applied at high film thicknesses in a single coat without crack-formation. The particles assist in maintaining a controlled slow release of toxin from the paint film, and can enhance the useful protective life thereof.

Abstract: Polymer aggregates in the form of discrete particles of controlled particle size below 150 microns maximum dimension which are themselves aggregates of primary particles of a polymer or polymers derived from at least one ethylenically unsaturated monomer together with from 0 to about 400%, by weight on the weight of the monomer, of an organic thickener compatible with the monomer, said aggregate particle containing from 0 to about 95% by weight of pigment and/or extender are made by providing an aqueous dispersion of the monomer and thickener, a hydrophilic colloid being present in the aqueous phase of the dispersion and pigment and/or extender optionally being present in either the aqueous phase or the disperse phase, introducing a polymerization initiator into the aqueous phase of the dispersion, and maintaining the dispersion under conditions of high shear and continuing polymerization to substantial completion thereof. The aggregates are useful in coating comositions, e.g. to provide a matt finish.