Patent ID: 7030199

Claim:
A process for producing a water-soluble or water-swellable polymer or copolymer comprising: providing an acid monomer alone, or in combination with at least one comonomer; partially or completely neutralizing said at least one monomer with at least one basic nitrogen compound; free-radical polymerizing said at least one monomer alone, or in combination with said at least one comonomer to form said water-soluble or water-swellable polymer or copolymer, wherein said free-radical polymerization is started at a temperature of from 0 to 50° C and is performed in aqueous solution at a maximum temperature of no more than 102-104° C, to provide an aqueous polymer or copolymer solution or an aqueous polymer or copolymer gel; and, subsequent to completion of said free-radical polymerization, heating said water-soluble or water-swellable polymer or copolymer at a temperature of from 120° to 240° ; wherein said heating is caried out for a time period between 10 minutes and 2 hours; wherein the water-soluble or water-swellable polymer or copolymer has a content of residual monomer of less than 50 ppm.