Patent ID: 8563664

Claim:
A crosslinked polymer derived from biodegradable or biomass based starting materials, characterized in that it is composed of a. structural units derived from lactic acid or other aliphatic or aromatic α-hydroxy acid monomers, or mixtures thereof, and b. a functionalisation agent, which is pentaerytritol or other at least trifunctional alcohol or at least trifunctional carboxylic acid, and c. an unsaturated difunctional monomer, which is itaconic acid or another comonomer which has, in addition to reactive end groups, at least one reactive double bond in its molecule, and d. an optional properties modifying comonomer which is a caprolactone, and e. a carboxylic acid, a derivative of an organic acid or a monofunctional alcohol which has a reactive double bond or a reactive end-group in its molecule, and is prepared from said components stepwise first by polycondensing a monomer mixture being composed at 60-97 mole-% of monomer units a, 0.5-15 mole-% functionalisation agent b, 0.1-39.5 mole-% unsaturated difunctional monomer c, and 0-39.4 mole-% properties modifying comonomer d, and then by adding into the mixture 0.5-60 mole-% component e which reacts partly or entirely with the end-groups of the prepolymer thus formed, which has a number average molar mass of 200-50,000 g/mole, whereafter the final product is produced by crosslinking.