Commercial Flame Retardancy of Unsaturated Polyester and Vinyl Resins: Review

Abstract

Chlorendic acid-based and tetrabromophthalate polyesters are major flame-retardant polyester resins, often used with antimony trioxide. For translucency, colloidal antimony pentoxide is preferred. Brominated diols are occasionally used. In the vinyl ester group, the adducts of acrylic or methacrylic acid with the diglycidyl ether of tetrabromobisphenol A are prodominant, and the styrene-cured resins often have advantageous physical properties and hydrolytic stability. Low styrene versions have air pollution advantages. Hydrated mineral fillers, notably ATH, are widely used at high loadings. ATH tend to reduce smoke, as does use of MMA instead of styrene. Oligourethane unsaturated resins, cured with MMA, also favor low smoke. Triethyl phosphate and dimethyl methylphosphonate enable viscosity reduction and enhance flame retardancy. Red phosphorus, ammonium polyphosphate and a char-forming organophosphate have also found niches. Phosphoruscontaining reactives have been largely unsuccessful. In situ melamine phosphate shows promise. Protective veils offer an alternative to flame retarding the resin itself.