Abstract: A polyester with a carbon black content of up to 20% by weight, based on the polyester, is condensed, after transesterification of DMT with diol, or after esterification of terephthalic acid with diol, with the aid of a titanium-based catalyst. The carbon black is added in the form of a carbon black dispersion together with the polycondensation catalyst to the transesterification product or esterification product. The carbon black dispersion comprises gas black or furnace black and a dispersing agent, and these are dispersed in diol. The diameter of the carbon black particles is below that of carbon black particles in a polyester using an antimony compound as catalyst.