Copolymer synthesis process

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 13 and/or Component C;
• and
• wherein at least a portion of the monomer of Component 13 and/or Component C is co-fed with the monomer of Component A during the stepwise or continuously changing addition of the monomer of Component A.

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 13 and/or Component C;
• and
• wherein about 50 to about 70 percent of the monomer of Component A is added into the reactor during a first reaction period following initiation of the polymerization reaction, during a second reaction period the addition rate of the monomer of Component A is decreased and about 25 to about 35 percent of the monomer of Component A is added to the reactor, and during a third reaction period the addition rate of the monomer of Component A is further decreased and the remaining about 5 to about 15 percent of the monomer of Component A is added to the reactor.

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;
• and
• wherein a polymerization pH in the aqueous medium is established so that, based on the free radical polymerization initiator used, the free radical formation per unit time is approximately at a maximum.