| 摘要 |
Pearl polyesters are made by polymerizing a cyclic ester of an a -hydroxy fatty acid in suspension in a liquid hydrocarbon and in the presence of 0.1-1.0% based on the ester of a halide of a metal of the first, second, fourth, fifth, six or seventh group of the Periodic System as catalyst and 0.05-1.0% based on the ester of a silicone oil. Preferably polymerization is effected at 60-180 DEG C. for 3-15 hours under an inert gas and with continuous stirring. The mechanical properties of the polymers may be improved by effecting polymerization in presence of an alcohol (e.g. octyl alcohol or trichloroethanol), a monoisocyanate (e.g. phenyl isocyanate) or a diisocyanate (e.g. hexamethylene, p-phenylene, 1 : 5-naphthalene or toluylene diisocyanate). Specified cyclic esters are glycolide and lactide which may be optically active, specified hydrocarbons are petroleum ether, di-, tetra- or hexa-hydrocumene and mixtures of either with toluene or xylene and specified catalysts are SnCl4, SnCl2 and TiCl4. Examples are given. |
