COBALT FREE PREPROMOTED UNSATURATED POLYESTER RESIN SYSTEM FOR ENGINEERED STONE

1 . A formable composition for the preparation of engineered stone comprising

(A) a cobalt free prepromoted unsaturated polyester resin system comprising

(i) a unsaturated polyester resin component;

(ii) a metal catalyst capable of catalyzing curing of said unsaturated polyester resin component;

(iii) a quaternary ammonium salt; and

(iv) optionally, one or more additives selected from the group consisting of reactive diluents, accelerators, co-promoters, dispersing agents, UV absorbers, stabilizers, inhibitors and rheology modifiers;

(B) an inorganic particulate material; and

(C) a peroxide component.

2 . The composition according to claim 1 , wherein the metal catalyst comprises zinc or copper.

3 . The composition according to claim 1 or 2 , wherein the quaternary ammonium salt is a benzyl-N,N,N-trialkylammonium salt or a N,N,N,N-tetraalkylammonium salt.

4 . The composition according to any of the preceding claims, wherein the unsaturated polyester resin component is obtained by reacting a mixture comprising a multicarboxylic acid component and a polyhydric alcohol component, wherein the multicarboxylic acid component and/or the polyhydric alcohol component comprises ethylenic unsaturation;

wherein preferably the multicarboxylic acid component is selected from the group consisting of aliphatic dicarboxylic acids, aliphatic tricarboxylic acids, aliphatic tetracarboxylic acids, aromatic dicarboxylaic acids, aromatic tricarboxylic acids and aromatic tetracarboxylic acids; and/or

wherein preferably the polyhydric alcohol is selected from the group consisting of aliphatic diols, aliphatic triols, aliphatic tetraols, aromatic diols, aromatic triols and aromatic tetraols.

5 . The composition according to any of the preceding claims, wherein the unsaturated polyester resin component is a reaction product of a mixture comprising at least 1, 2 or 3 diols selected from the group consisting of propylene glycol, dipropylene glycol, ethylene glycol, and diethylene glycol; and at least 1, 2, 3 or 4 acids selected from the group consisting of maleic acid, isophthalic acid, phthalic acid, and adipic acid, or their acid anhydrides.

6 . The composition according to any of the preceding claims, wherein the cobalt free prepromoted unsaturated polyester resin system comprises a reactive diluent selected from the group consisting of styrene, substituted styrene, nono-, di- and polyfunctional esters of monofunctional acids with alcohols or polyols, mono-, di- and polyfunctional esters of unsaturated monofunctional alcohols with carboxylic acids or their derivatives.

7 . The composition according to any of the preceding claims, wherein the inorganic particulate material comprises quartz aggregates and/or quartz fillers.

8 . The composition according to any of the preceding claims, wherein the inorganic particulate material has a particle size distribution such that

about 30 wt.-% to about 70 wt.-% of the particles have a particle size within the range of from about 0.1 μm to about 0.3 μm;

about 5 wt.-% to about 30 wt.-% of the particles have a particle size within the range of from about 0.3 μm to about 0.6 μm; and

about 10 wt.-% to about 40 wt.-% of the particles have a particle size within the range of from about 20 μm to about 60 μm.

9 . The composition according to any of the preceding claims, wherein the peroxide component is cumene hydroperoxide or methyl isobutyl ketone peroxide.

10 . The composition according to any of the preceding claims, which has a pot life of at least about 30 minutes.

11 . The composition according to any of the preceding claims, wherein the content of the cobalt free prepromoted unsaturated polyester resin system is about 0.1 wt.-% to about 30 wt.-%, relative to the total weight of the formable composition; and/or wherein the content of the inorganic filler material is about 70 wt.-% to about 99.9 wt.-%, relative to the total weight of the formable composition.

12 . A method for the preparation of engineered stone comprising the steps of

(a) preparing a formable composition by mixing

(A) a cobalt free prepromoted unsaturated polyester resin system as defined in any of claims 1 to 6 ;

(B) an inorganic particulate material as defined in any of claim 1 , 7 or 8 ; and

(C) a peroxide component as defined in any of claim 1 or 9 ;

(b) forming the composition prepared in step (a) into a desired shape; and

(c) allowing the composition formed in step (b) to cure.

13 . Engineered stone obtainable by the method according to claim 12 .

14 . A cobalt free prepromoted unsaturated polyester resin system comprising

(i) a unsaturated polyester resin component;

(ii) a metal catalyst comprising zinc or copper and being capable of catalyzing curing of said unsaturated polyester resin component;

(iii) a benzyl-N,N,N-trialkylammonium salt or a N,N,N,N-tetraalkylammonium salt; and

(iv) optionally, one or more additives selected from the group consisting of reactive diluents, accelerators, co-promoters, dispersing agents, UV absorbers, stabilizers and rheology modifiers.

15 . Use of a cobalt free prepromoted unsaturated polyester resin system as defined in any of claim 1 to 6 or 14 for the preparation of engineered stone.