Patent ID: 8513343

Claim:
An unsaturated polyester resin composition comprising an unsaturated polyester resin, a manganese compound, a 1,3-dioxo compound, and a base, wherein the manganese compound is a manganese 2+ or manganese 3+ salt or complex, the manganese compound is present in an amount of at least 0.01 mmol manganese per kg of primary resin system, and wherein the base is an organic base with pK a ≧10 or the base is an alkali metal or earth alkaline metal compound, wherein the alkali earth or alkali metal compound is an oxide, hydroxide, carboxylate, carbonate or hydrocarbonate, and wherein the molar ratio between the 1,3-dioxo compound and a basic functionality of the base is from 170:1 to 1:30, and wherein the resin composition has a cobalt concentration of lower than 0.01 mmol Co per kg primary resin system, and the resin composition is curable with a peroxide, and wherein the 1,3-dioxo compound is a compound having the following formula: wherein, X and Y are individually H, C 1 -C 20 alkyl, C 6 -C 20 aryl, alkylaryl, arylalkyl, part of a polymer chain, OR 3 , or NR 3 R 4 ; R 1 , R 2 , R 3 , and R 4 each individually represents hydrogen (H), or a C 1 -C 20 alkyl, aryl, alkylaryl or arylalkyl group, and each optionally may contain one or more hetero-atoms selected from the group consisting of oxygen atoms, phosphor atoms, nitrogen atoms, sulphur atoms and substituents thereof; a ring optionally may present between R 1 and R 2 , R 1 and R 3 , R 2 and R 4 , or combinations thereof; and at least one of R 3 and R 4 may optionally be part of a polymer chain, attached to a polymer chain or contain a polymerizable group.