Polyester plasticizers

Claim 1

A polyester having the formula M(P).sub.a (D).sub.b (L).sub.c M I in which M is the residue of one or more aliphatic monocarboxylic acids containing from 4 to 12 carbon atoms or one or more saturated straight or branched chain monohydric alcohols containing from 4 to 12 carbon atoms, P is the residue of one or more saturated straight or branched chain aliphatic diols containing from 2 to 4 carbon atoms, D is the residue of a mixture of one or more aliphatic dicarboxylic acids containing from 4 to 6 carbon atoms and a proportion above 10 mole % of the total acids used, of one or more aromatic dicarboxylic acids or anhydrides selected from the group consisting of o-phthalic acid, phthalic anhydride and isophthalic acid, L is the residue of 6-hydroxy caproic acid, each of the residues being joined together by ester linkage, residues P, D and L being distributed at random throughout the molecule, a, b and c each having a value greater than 0, the amount of residue of hydroxy acid being from 10 mole % to 90 mole % based on the total number of moles of reactants and the molar ratios of the remaining reactants being chosen so that the average molecular weight of the product is from 500 to 1400, which is prepared by reacting in one-step a mixture of the following components (a) from 10 to 90 mole % of epsilon caprolactone or the corresponding hydroxy acid, (b) a hydroxylic component which comprises one or more saturated straight or branched chain aliphatic diols containing from 2 to 4 carbon atoms, (c) an acidic component which comprises a mixture of one or more aliphatic dicarboxylic acids containing from 4 to 6 carbon atoms and a proportion above 10 mole % of the total acids used of one or more aromatic dicarboxylic acids or anhydrides selected from the group consisting of o-phthalic acid, phthalic anhydride and isophthalic acid, and, (d) one or more aliphatic monocarboxylic acids containing from 4 to 12 carbon atoms or one or more saturated straight or branched chain monohydric alcohols containing from 4 to 12 carbon atoms such that the hydroxylic components are used in stoichiometric amounts or up to 20% excess over the stoichiometric amounts related to the acidic components.