| 摘要 |
<p>Process for the preparation of polyesters from aliphatic dicarboxylic acids and polyalkylpiperidyl diols The invention relates to a novel process for the preparation of compounds of the formula I (I) wherein n is a value from 8 to 25, R1 and R2, each independently of the other, are C1-C18alkylene, C2-C18alkylene which is interrupted by -O-, -S- or N(R)-, in which R is hydrogen or C1-C4alkyl, or are C4-C8alkenylene, and R3 is C1-C4-alkyl, by polycondensation of a diol of the formula II (II) with a dicarboxylic acid ester of the formula III (III) which process comprises stirring the reaction medium which contains an excess of 2 to 50 mol.%, based on the diol of formula II, of the dicarboxylic acid ester of the formula III, in the presence of at least 0.03 mol.% of a suitable catalyst, until the bulk of the alkanol of the formula R3OH formed during the reaction is distilled off, under a pressure of 0.7 to 1.3 bar, and thereafter stirring under a pressure of less than 5 mbar, in the temperature range from 100.degree. to 170.degree.C, and subsequently working up the resultant melt in conventional manner. The process comprises stirring the reaction medium which contains an excess of 2 to 50 mol.%, based on the diol of formula II, of the dicarboxylic acid ester of the formula III, in the presence of at least 0.03 mol.% of a suitable catalyst, until the bulk of the alkanol of the formula R3OH formed during the reaction is distilled off, under a pressure of 0.7 to 1.3 bar, and thereafter stirring under a pressure of less than 5 mbar, in the temperature range from 100.degree. to 170.degree.C, and subsequently working up the resultant melt in conventional manner.</p> |
