Vinyl ester resin compositions

1. A cured vinyl ester resin composition, comprising a primary resin system comprising:

(a) a peroxide cured vinyl ester resin,

(b) a manganese compound which is a manganese carboxylate or a manganese acetoacetate,

(c) a 1,3-dioxo compound having the following formula:

wherein,

X,Y═H, C 1 -C 20 alkyl, C 6 -C 20 aryl, alkylaryl, arylalkyl, part of a polymer chain, OR 3 , NR 3 R 4 ; R 1 , R 2 , R 3 , and R 4 each individually may represent hydrogen (H), or a C 1 -C 20 alkyl, C 6 -C 20 aryl, alkylaryl or arylalkyl group, that each optionally may contain one or more hetero-atoms selected from the group consisting of oxygen, phosphor, nitrogen and sulphur atoms; and/or substituents;

a ring may be present between R 1 and R 2 , R 1 and R 3 , and/or between R 2 and R 4 ;

R 3 and/or R 4 may be part of a polymer chain, may be attached to a polymer chain or may contain a polymerizable group, and

(d) a base, wherein the base is an organic base with pKa≧10 selected from amines or the base is an alkaline metal or earth alkaline metal compound, wherein

the amount of the 1,3-dioxo compound is between 0.05 and 5% by weight, calculated on the total weight of the primary resin system, and wherein

the base is present in an amount of from 0.001 to 2000 mmol/kg of the primary resin system, and

wherein

the composition has a molar ratio between the manganese compound and a basic functionality of the base of 1:1 to 1:1500.

2. The resin composition according to claim 1 , wherein the manganese compound is present in an amount of 0.01 to 100 mmol manganese per kg of primary resin system.

3. The resin composition according to claim 1 , wherein X and/or Y are/is C 1 -C 20 alkyl and/or C 1 -C 20 aryl.

4. The resin composition according to claim 1 , wherein X and/or Y is a methyl group.

5. The resin composition according to claim 4 , wherein the 1,3-dioxo compound is acetylacetone.

6. The resin composition according to claim 1 , wherein the metal base is a potassium compound.

7. The resin composition according to claim 1 , wherein the composition has a molar ratio between the dioxo compound and a basic functionality of the base of 170:1 to 1:30.

8. The resin composition according to claim 1 , wherein the composition has a molar ratio between the manganese compound and the dioxo compound of 1:3 to 1:5000.

9. The resin composition according to claim 1 , further comprising a radical inhibitor.

10. The resin composition according to claim 1 , wherein the resin composition is essentially free of cobalt.

11. Objects and structural parts which comprise the peroxide cured resin composition according to claim 1 .

12. The resin composition according to claim 1 , wherein the peroxide is at least one selected from the group consisting of hydroperoxides, perethers and perketones.

13. The resin composition according to claim 12 , wherein the peroxide is methylethylketone peroxide.

14. The resin composition according to claim 1 , wherein the amine base is a tertiary amine.

15. The resin composition according to claim 6 , wherein the potassium compound is a potassium carboxylate.

16. The resin composition according to claim 1 , wherein the molar ratio between the manganese compound and the basic functionality of the base is 1:5 to 1:60.

17. The resin composition according to claim 7 , wherein the molar ratio between the dioxo compound and the basic functionality of the base is 13:1 to 1:30.

18. The resin composition according to claim 8 , wherein the molar ratio between the manganese compound and the dioxo compound is 1:3 to 1:400.

19. The resin composition according to claim 9 , wherein the radical inhibitor is at least one selected from the group consisting of phenolic compounds, stable radicals, catechols and phenothiazines.