Patent ID: 8349968

Claim:
A method for radically curing an unsaturated polyester resin or vinyl ester resin composition, comprising: (i) providing a resin composition comprising an unsaturated polyester resin or vinyl ester resin, at least 10 ppm radical inhibitor, one or more reactive diluent and having an acid value of from 0.001 to 300 mg KOH/g of the resin composition, wherein the reactive diluent is a methacrylate and/or styrene, and (ii) curing the resin composition in the absence of peroxide, but in the presence of at least 20 mmol Mn/kg of primary resin system and a thiol-containing compound providing at least 10 mmol of thiol/kg of primary resin system and less than 500 mmol thiol/kg of primary resin system, wherein the molar ratio between manganese and thiol groups of the thiol-containing compound is from 1.5:1 to 1:8, and wherein the primary resin system consists of the unsaturated polyester resin or vinyl ester resin, any additive present in the resin composition that is soluble in the resin and any solvent present in the resin composition.