Polymer, process and composition

Abstract

There is described a process for producing a gel free hyperbranched polyamide polymer having primary amino groups (useful as a crosslinker). The process comprises the step of reacting at least one diamine and at least one unsaturated diester in a molar ratio of diamine to diester greater than 1 but less than 3 (preferably 2.1 to 2.9); to form the polyamide in a two stage reaction Michael addition and then amidation. The diamine in kept in excess with at least 5% of water by total weight of the diamine and diester, a reaction temperature less than the boiling point of the diamine; and is held under reduced pressure (30 mbar to 1 atms). Gelation does not occur even after substantially all ethylenic (—C═C—) double bonds; and >95% ester [—C(O)═O] groups have reacted. This violates the Flory rules which predict a gel would form based on the number of functional groups present and their degree of conversion.

Dependencies are inferred from the claim text.