| 摘要 |
In the manufacture of highly polymeric polyesters by polycondensing a glycol ester of an aromatic dicarboxylic acid, there is used as a polycondensation catalyst an organotitanium compound of formula TiRn where R is an aliphatic, aromatic or cycloaliphatic hydrocarbon radical and n is 2, 3 or 4. Preferred catalysts are cyclopentadienyl titanium compounds (titanocenes), polyalkyl titaniums and polyaryl titaniums. If the initial glycol ester is made by an ester-interchange reaction, the organo-titanium compounds may also be used as catalysts for this reaction. Specified polyesters are those of terephthalic or pyridinedicarboxylic acids and ethylene glycol or cyclohexanedimethanols. Examples describe the manufacture of polyethylene terephthalate by reacting dimethyl terephthalate, ethylene glycol and possibly, zinc di(monomethyl terephthalate). |
