Лако-красочные материалы — производство

The original water based paints, distempers, were prepared by emulsifying an oil bound paint in water. They had a limited use on porous surfaces where oil absorption into the substrate was reduced in relation to oleoresinous finishes. The replacement of distempers by pigmenting large particle size polyvinyl acetate emulsions, gave faster film drying and better ‘breathing’. Most of the early problems derived from the dispersed nature of the polymer. In a conventional oleoresinous paint the resin contributed directly to the vehicle viscosity and to dispersion of the pigment, whereas in a latex paint the polymer particles acted more like pigment than’vehicle. It was found that additions of colloid, sequesterant and humectants were necessary to give good performance. Latex paints have lower pigment volume contents (PVC) than oil paints. This is partly because high PVC’s adversely affect film formation; in oil based undercoats and matt finishes, a high PVC is necessary for gloss, whilst small quantities of pigment will produce mattness in latex paints.