EFFECT OF PIGMENT VOLUME CONCENTRATION AND LATEX PARTICLE-SIZE ON PIGMENT DISTRIBUTION

Pigment distribution in latex paints has been investigated by experime nts using a combination of computer modelling, experimental model syst ems and pigmented paints. This paper deals with the geometric effects of variables such as pigment volume concentration and latex particle s ize on the pigment distribution in water-borne coatings. Physico-chemi cal effects, such as particle surface potentials and ionic strength of the serum, are dealt with in a subsequent paper. Computer modelling a nd experimental model systems gave a clear picture of the geometric ef fects of PVC and latex particle size on pigment distribution. Higher P VC leads to a higher density of pigment in the film and consequently m ore crowding of pigment particles, but has no further effect on the qu ality of pigment distribution. Computer and physical model systems sho w that pigment distribution is improved by reducing the latex particle size. From purely geometric considerations, the best results should b e obtained with infinitely small latex particles. A series of model pa ints pigmented with titanium dioxide showed that the results were vali d for latex/pigment size ratios from 0.75 to 1.5. (C) 1997 Elsevier Sc ience S.A.