Polyurethane dispersions based on polycarbonate polyols and suitable for use in personal care products

A process for preparing an aqueous polyurethane dispersion suitable for use in personal care products, comprising:

• 1) preparing a prepolymer according to the formula:
• wherein
• R1 represents a bivalent radical of a polycarbonate polyol,
• R2 represents a radical of an aliphatic or cycloaliphatic polyisocyanate,
• R3 represents a radical of a low molecular weight diol, optionally substituted with ionic groups,
• n is from 1 to 5, and
• m is >1;
• by reacting:
• 1a) at least one polycarbonate polyol,
• 1b) one or more aliphatic or cycloaliphatic polyisocyanates, and
• 1c) at least one low molecular weight diol optionally substituted with ionic groups;
• 2) reacting the prepolymer with at least one monohydroxyl-functional polyalkylene oxide with a number average molecular weight equal to or less than about 3,000;
• 3) chain-extending the prepolymer with
• 3a) at least one chain extender according to the formula:
• H2N—R4—NH2
• wherein R4 represents an alkylene or alkylene oxide radical not substituted with ionic or potentially ionic groups, and
• 3b) optionally 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:
• H2N—R5—NH2
• wherein R5 represents an alkylene radical substituted with ionic or potentially ionic groups,
• in the presence of an organic solvent to form a polyurethane;
• 4) dispersing the polyurethane in water;
• and
• 5) removing the organic solvent, resulting in an aqueous polyurethane dispersion;
• wherein the radical of the monohydroxyl-functional polyalkylene oxide constitutes between about 0.1 wt. % to about 5 wt. % of the polyurethane.