Process of making urethane rheology modifiers

Claim 1

A process for making a urethane rheology modifier characterized in having a branched structure and hydrophobic tails, comprising the steps of: (1) reacting in an organic solvent (a) for each 8 moles of a polyalkylene oxide having a molecular weight of from about 2,000 to about 20,000; (b) about 0.1 moles to about 3 moles of a polyfunctional material, wherein said material has at least 3 active hydrogens capable of reacting with isocyanate or is a polyisocyanate having at least 3 isocyanate groups; (c) about 4 moles to about 15 moles of a diisocyanate; (d) less than about 3 moles water; and (e) an amount of additional diisocyanate to compensate for any water present, wherein the organic solvent is selected from the group consisting of 1-methyl-2-pyrrolidinone, dimethyl formamide, dimethyl acetamide, gamma butyrolactone, dioxane, dimethyl and diethyl ethers of ethylene glycol and diethylene glycol, acetonitrile, and mixtures thereof; and (2) end-capping the reaction product of step (1) with a monofunctional active hydrogen-containing compound or monoisocyanate so as to cap substantially all free isocyanate or hydroxyl groups.