Colored rigid thermoplastic resin compositions and a process for their production

The colored rigid thermoplastic resin composition that is prepared by incorporating in a rigid thermoplastic resin composition an amount of a non-plasticizing liquid pigment dispersion that will provide at least 0.1% by weight of pigment, based on the weight of the composition, said non-plasticizing liquid pigment dispersion containing

• (a) 5% to 80% by weight of at least one pigment and
• (b) 20% to 95% by weight of an unsaturated polyester vehicle that comprises
• (1) 50% to 100% by weight of an unsaturated polyester that is the product of the reaction of a dicarboxylic acid component containing 80 to 90 mole percent of at least one unsaturated aliphatic dicarboxylic acid having 4 to 8 carbon atoms and 10 to 20 mole percent of at least one saturated aromatic dicarboxylic acid with an alcohol component containing 40 to 60 mole percent of a glycol having 2 to 6 carbon atoms and 40 to 60 mole percent of a monohydric alcohol having 6 to 12 carbon atoms, in the amount of 0.4 mole to 0.6 mole of the dicarboxylic acid component per mole of the alcohol component, and
• (2) 0 to 50% by weight of an unsaturated monomer capable of reacting with said unsaturated polyester to form cross-linkages.