Patent ID: 8114938

Claim:
A process for preparing a hair fixative comprising: a. preparing an aqueous polyurethane dispersion by i. forming a isocyanate-functional prepolymer by reacting 1a) a polyol, 1b) an aliphatic or cycloaliphatic polyisocyanate, and 1c) a low molecular weight diol optionally substituted with ionic groups; ii. chain-extending the prepolymer with 2a) at least one chain extender according to the formula: H 2 N—R 4 —NH 2 wherein R 4 represents an alkylene or alkylene oxide radical not substituted with ionic potentially ionic groups, and 2b) at least one chain extender selected from the group consisting of the sodium salt of N-(2-aminoethyl)-2-aminoethane sulfonic acid and compounds according to the formula: H 2 N—R 5 —NH 2 wherein R 5 represents an alkylene radical substituted with ionic or potentially ionic groups, in the presence of an organic solvent to form a polyurethane; iii. dispersing the polyurethane in water; and iv. removing the organic solvent, resulting in an aqueous polyurethane dispersion; and b. mixing the polyurethane dispersion with biocide.