Process for preparing highly-polymeric,pigmented or delustered polyalkylene or polycycloalkylene terephthalates

摘要

Pigmented or delustered polyalkylene or polycycloalkylene terephthalates are made by polycondensing a bis-(o -hydroxyalkyl) or bis-(hydroxymethylcycloalkyl) terephthalate first at a temperature of 230 DEG to 250 DEG C. whilst the pressure is gradually reduced to between 1 and 0.3 mm. of Hg and then at a temperature of 272 DEG to 278 DEG C., the pigment or delustering agent being added prior to the formation of the polyester. Specified glycol components of the polyester are ethylene glycol, 1:3-propanediol, 1:4 - butanediol and 1:4 - dimethylolcyclohexane whilst specified pigments and delustering agents are carbon black, lithopone and titanium dioxide. In the example, a dispersion of carbon black in ethylene glycol containing a condensate of b -naphthalene sulphonic acid and formaldehyde was added to a mixture of dimethyl terephthalate and ethylene glycol, then ester-interchange was effected in the normal way followed by polycondensation as specified above.