Patent ID: 7973110
Filing Date: 2011-07-05
Classification: C04B,C08F,Y10S

Abstract:
1. A process for the preparation of a non-ionic copolymer comprising at least one hydrolysable monomer residue and at least one polyether macromonomer residue in a semicontinuous mode of operation in a polymerization apparatus containing a polymerization reactor associated with a metering device, the process comprising: introducing at least a portion of the polyether macromonomer with low reactivity and water into the polymerization reactor, wherein the hydrolysable monomer with higher reactivity which is added thereto forms an aqueous medium polymerization reaction mixture, optionally wherein the aqueous medium is present in the form of an aqueous solution; introducing at least a portion of the hydrolysable monomer into the metering device; adding at least a portion of the hydrolysable monomer into the polymerization reactor from the metering device; passing a free radical polymerization initiator into the polymerization reactor before and/or during the addition of the hydrolysable monomer into the polymerization reactor, wherein the hydrolysable monomer and the polyether macromonomer are reacted in the aqueous medium polymerization reaction mixture by free radical polymerization with formation of the non-ionic copolymer; and, subjecting the reaction mixture to polymerization while an addition rate of the hydrolysable monomer and/or at least a component of the free radical polymerization initiator is varied stepwise or continuously; wherein no monomer is introduced into the polymerization reactor to incorporate ionic cement binding sites into the non-ionic copolymer prior to mixing the copolymer in an alkaline aqueous environment; wherein the hydrolysable monomer is at least one ethylenically unsaturated hydrolysable monomer of Component A and the polyether macromonomer is at least one ethylenically unsaturated polyoxyalkylene ether-based monomer of Component B and/or Component C; and wherein the at least one ethylenically unsaturated polyoxyalkylene ether-based monomer of Component B and/or Component C is added into the reactor in advance, and the at least one ethylenically unsaturated hydrolysable monomer of Component A is added thereto with an addition rate that changes at least one time.