| 摘要 |
The improved method of the present invention comprises making selected polyesters by condensation polymerization of polycarboxylic acids with a plurality of diols, the diols being in a eutectic mixture having a melting point below that of the individual diols in the mixture. Thus, the eutectic mixture is charged in the liquid state with a sufficient amount of the acid and reacted under condensation conditions to form an ester and to polymerize the ester to the desired extent. A substantial saving in the amount of labor necessary to prepare the polyester is provided by the present method. The diols are preferably selected from the group consisting of neopentyl glycol, trimethyl pentanediol, cyclohexane dimethanol, and 1,6 hexanediol. Usually two diols are employed to form the eutectic mixture. They are normally waxy solids at ambient temperature, but are liquid when mixed in the proper proportions to provide the eutectic. Usually the molar ratio of the eutectic mixture of the two diols varies between about 30:70 and about 70:30. One preferable eutectic mixture comprises neopentyl glycol and 1,6 hexanediol in a molar ratio of about 1:1. |
