Patent ID: 7687568

Claim:
A polyester colorant concentrate comprising (a) a polyester carrier material, (b) at least one colorant selected from the group consisting of dyes pigments or a combination thereof, (c) 0.1 to 2 parts by weight per part by weight of a copolyester comprising the reaction product of (A) at least one aliphatic primary dihydric alcohol having 2 to 6 carbon atoms and (B) a mixture (100 mol %) of 25 to 65 mol % terephthalic acid, 25 to 65 mol % isophthalic acid, and 5 to 20 mol % phthalic acid, or (B) a mixture (100 mol %) of 40 to 55 mol % terephthaiic acid, 25 to 50 mol % isophthalic acid, and 7 to 23 mol % sebacic acid wherein the copolyester has (i) a melting range between 120 and 160° C.; (ii) a melt viscosity MV of 12 to 126 Pa*s, measured at 190° C. and 2.16 kg in accordance with ISO 1133; and (iii) a melt viscosity factor MF of −2.3 to −0.3 Pa·s/deg, determined with a temperature increase in the range from 160° C. to 240° C. at a shear rate of 10s −1 .