Patent ID: 8629207

Claim:
An aqueous coating formulation comprising a substituted, branched polyethyleneimine which is obtained by a process comprising reacting a branched polyethyleneimine having a weight-average molecular weight of from 500 to 10,000 g/mol with a carboxylic acid derivative of formula (I) R—(C═O)X (I), wherein R is a C 5 to C 18 alkyl group or a C 5 to C 18 alkenyl group, X is a halogen, a hydroxyl group, or a group R—(C═O)—O—, a molar amount of the carboxylic acid derivative in the reacting is from 3 to 10 mol % of a molar amount of ethyleneimine employed in preparing the branched polyethyleneimine, the reacting comprises formation and removal of a byproduct HX, and the formulation is configured to coat a substrate that comprises tannin.