COPOLYMER SYNTHESIS PROCESS Russian patent published in 2014 - IPC C08F2/01 C08F220/18 C08F220/26 C08F220/56 C08F283/06 C08F290/06 C09K8/42 C04B24/26 

FIELD: chemistry.

SUBSTANCE: process is carried out in continuous mode in a polymerisation apparatus, having a polymerisation reactor which is integrated with a measuring device. The method involves feeding a low-reactivity polyester macromonomer and water into the polymerisation reactor. A portion of a highly reactive, hydrolysable monomer is then added and an aqueous polymerisation medium is formed. At least a portion of the hydrolysable monomer is initially fed into the measuring device and then into the polymerisation reactor. Free-radical polymerisation is then carried out in an aqueous medium. Before and/or while adding the hydrolysable monomer, a free-radical polymerisation initiator is fed into the polymerisation reactor. During polymerisation, the rate of adding the hydrolysable monomer and/or initiator is varied in steps or continuously. No monomer for including ionic cement binding sites into a nonionic copolymer is fed into the polymerisation reactor. The hydrolysable monomer used is at least one ethylenically unsaturated hydrolysable monomer A. The polyester macromonomer used is at least one ethylenically unsaturated monomer of polyoxyalkylene ester B and/or C. Component B and/or C can be fed into the reactor in advance and component A is then added thereto at a rate which varies at least once.

EFFECT: invention enables to obtain a nonionic copolymer which is capable of prolonging placeability of the cementing mixture over s long period of time, which enables to minimise the need to adjust deposits during preparation and at the construction site, reduce repeated dosing of plasticising additives into the cement mixture.

26 cl, 10 dwg, 9 tbl, 36 ex