Low Solvent Coatings

The aim of this project was to investigate the feasibility of acrylic plastisols as a new type of low solvent industrial coating. Consisting essentially of a dispersion of emulsion or suspension grade polymer in a high boiling solvent-plasticiser, the coating is applied to the substrate and then heated to allow the plasticiser to swell and dissolve the polymer particles. The result on cooling is a tough and flexible coating. The plastisol market has traditionally been dominated by poly(vinyl chloride) whose stability in plasticiser is widely believed to be due to the presence of microcrystalline domains within the polymer that prevents premature swelling and dissolution of the particles. However manufacturers are searching for alternative polymers. Acrylic polymers, which offer a number of distinct advantages over poly(vinyl chloride) such as superior exterior durability and a more favourable environmental image, are, because of their amorphous character, not particularly stable in plasticiser and result in plastisols that gel prematurely.

Work at PRA was specifically aimed at designing acrylic polymers with other forms of intermolecular association to assume the role of the microcrystallinity of poly(vinyl chloride). These associations took the form of hydrogen bonds, dipole-dipole interactions, metal ion and covalent cross-links. The effects of particle size and polymer molecular weight and application of the novel concept of osmotic de-swelling of networks were also investigated.

Further Information

If you are interested in this, or any other project, please contact Richard Holman.