New generation multi-hollow opaque polymer pigments
Turkish researchers synthesised a new generation multi-hollow opaque polymer pigment by suspension polymerisation of "water-in-oil-in-water” emulsion method, where a methyl methacrylate and ethylene glycol dimethacrylate monomer mixture was used as oil phase.
They studied effects of surfactant and cosurfactant composition in terms of “hydrophilic/lipophilic balance” on the stability of the “water-in-oil” emulsion and the size of water droplets.
Pigments exhibit low gloss values
Low droplet sizes and the optimum stability were obtained with “Span 80&Tween 80” surfactant mixture at an HLB value of 8. The desired size distribution was obtained at “monomer/surfactant/water” ratio of 75.5/9.4/15.1 at an ultrasonic mixing power of 80 W lasting for 30s. The surface morphology and hollow structure of polymer pigments were analysed by scanning and transmission electron microscopy techniques. L*a*b colour and gloss properties of polymer pigments were examined. The opacity values were assessed by contrast ratio measurements, and the pigments provided up to 97.3% opacity with 50% v/v solid content in resin. In addition, the pigments exhibited low gloss values and yielded matte films.
The study is published in: Journal of Applied Polymer Science.
