PROCESS FOR PRODUCING WATERRSOLUBLE OR WATERRDISTRIBUTABLE POLYHYDOXYL COMPOUNDS

1524276 High molecules weight polyhydroxyl compounds; polyurethanes BAYER AG 22 June 1976 [25 June 1975] 25791/76 Heading C3R Polyhydroxyl compounds which are soluble or dispersible in water and which are reacted with polyisocyanates to produce polyurethanes are prepared by reacting from 0À08 to 75% of the hydroxyl groups of an organic polyhydroxyl compound having a M.W. of from 400 to 10,000 which is insoluble and non-dispersible in water with (a) a cyclic organic acid anhydride in a ring-opening addition reaction, the resulting carboxyl groups being at least partly converted into hydrophilic groups by neutralization or quaternization or (b) a compound containing at least one hydrophilic group and at least one group which undergoes an addition reaction with OH groups, or (c) a compound containing at least one group which is capable of being converted into a hydrophilic group and at least one group which undergoes an addition reaction with OH groups, the groups which are capable of being converted into hydrophilic groups being at least partly converted by neutralization or quaternization after the addition reaction with the polyhydroxyl compound. The organic polyhydroxyl compound used as starting material is most preferably a polyester or polyether conventionally used in the polyurethane art. Preferred anhydrides used in (a) are organic dicarboxylic acid anhydrides, e.g. phthalic acid anhydride and maleic acid anhydride, and the neutralizing agent may be an inorganic or organic base. Alternative process (b) is particularly preferred, especially when the reactant is the reaction product of a monohydroxypolyalkylene oxide, containing a major amount of ethylene oxide units, and a polyisocyanate at an NCO/OH ratio of 1À2 : 1 to 2À2 : 1. The compounds used in alternative process (c) may be monoisocyanates which contain tertiary amino groups or sulphonic acid groups. The modified polyhydroxyl compounds, apart from being water-soluble or dispersible, may also be suitable as dispersing agent for unmodified polyhydroxyl compounds.