Preparation and Characterization of Phenol Resin Coatings Containing Silica

Abstract

This paper shows that silica sol derived from silicon alkoxide is an excellent additive for resin. Silica disperses into the matrix of resin by using emulsion type phenol resin, and it can mix in resin homogeneously by using resol type phenol resin. It is well known that silica sol derived from silicon alkoxide consists of ultra fine particles. In the present study, a clear colorless silica sol has been prepared by hydrolysis of tetraethyl orthosilicate (TEOS) using p-toluenesulfonic acid monohydrate as a catalyst. The silica sol was mixed well in resol type phenol resin, and the contents of silica in coatings was higher in the case of resol type phenol resin than that of emulsion type phenol resin. The coatings were evaluated on the degree of surface-cracks, on chemical resistance (acidic and basic aqueous solutions) based on peeling from substrate, on hardness and on resistance to fire. Emulsion type phenol resin and resol type phenol resin were used. Both of the coatings up to 30mass% silica-contents in the former and 45mass% silica-contents in the latter were crack-free. Chemical resistance was not degra-dated by the addition of silica. Hardness and resistance to fire were remarkably improved by the addition of silica sol.