Thixotropic polyester compositions containing an organophilic clay gellant

A thixotropic cross-linkable polyester composition comprising an unsaturated polyester and an unsaturated aromatic monomer having dispersed therein an organophilic clay gellant comprising the reaction product of a smectite-type clay selected from the group consisting of hectorite and sodium bentonite, and a methyl benzyl dialkyl ammonium compound or a dibenzyl dialkyl ammonium compound, said dialkyl groups comprising a mixture of long chain alkyl radicals, wherein 20% to 35% of said long chain alkyl radicals contain 16 carbon atoms and 60% to 75% of said long chain alkyl radicals contain 18 carbon atoms, the amount of said ammonium compound reacted with said clay being from 100 to 120 milliequivalents per 100 grams of clay based upon 100% active clay, wherein said unsaturated polyester comprises at least 40% of said composition and wherein said organophilic clay gellant comprises up to 4% by weight of said composition.

A process for preparing thixotropic unsaturated polyester composition comprising;

• (a) forming a pregel of an aromatic unsaturated monomer with an organophilic clay gellant comprising the reaction product of a smectite-type clay having a cation exchange capacity of at least 75 milliequivalents per 100 grams of clay and a methyl benzyl dialkyl ammonium compound or a dibenzyl dialkyl ammonium compound, wherein the alkyl groups contain 14 to 20 carbon atoms, the amount of said ammonium compound reacted with said clay being from 100 to 120 milliequivalents per 100 grams of clay based on 100% active clay;
• and
• (b) combining said pregel with a liquid unsaturated polyester to form a thixotropic composition.

A process for preparing thixotropic unsaturated polyester composition comprising;

• (a) forming a pregel of an aromatic unsaturated monomer with an organophilic clay gellant comprising the reaction product of a smectite-type clay having a cation exchange capacity of at least 75 milliequivalents per 100 grams of clay and a methyl benzyl dialkyl ammonium compound or a dibenzyl dialkyl ammonium compound, said dialkyl groups comprising a mixture of long chain alkyl radicals, wherein 20% to 35% of said long chain alkyl radicals contain 16 carbon atoms and 60% to 75% of said long chain alkyl radicals contain 18 carbon atoms, the amount of said ammonium compound reacted with said clay being from 100 to 120 milliequivalents per 100 grams of clay based on 100% active clay;
• and
• (b) combining said pregel with a liquid unsaturated polyester to form a thixotropic composition.