| 摘要 |
Copolymers which contain, as copolymerized monomer units, monoethylenically unsaturated mono- and dicarboxylic acids are prepared by a process in which (a) from 10 to 60% by weight of a monoethylenically unsaturated dicarboxylic acid of 4 to 6 carbon atoms, its salt and/or, if appropriate, its anhydride, (b) from 90 to 40% by weight of a monothylenically unsaturated monocarboxylic acid of 3 to 10 carbon atoms and/or its salt and (c) from 0 to 20% by weight of another, carboxyl-free monoethylenically unsaturated monomer which is copolymerizable with (a) and (b), the percentages being based on the sum of the monomers, are polymerized in the presence of from 0.5 to 5% by weight of a water-soluble free-radical-forming initiator in an aqueous medium at from 60 DEG to 150 DEG C., and, if appropriate, their anhydride groups are hydrolyzed, the monomers (a) and (b) being employed in a form such that from 20 to 80% of their amount is neutralized during the polymerization reaction, wherein the copolymerization is carried out continuously in a reactor cascade comprising several reactors, and an aqueous solution of a pre-prepared copolymer of (a), (b) and, if appropriate, (c) is initially introduced into all the reactors and heated to the required reaction temperature, the total amount of unneutralized or partially neutralized (a), not less than 40% by weight of unneutralized or partially neutralized (b), where relevant, all or some of (c), and some or all of the amount of initiator required for polymerization, with or without the amount of neutralizing agent required for the neutralization according to the definition, are metered into the first reactor, the remaining amount of unneutralized or neutralized (b) and, where relevant, (c), and any remaining amount of initiator and neutralizing agent which may be required are introduced into the second reactor or are distributed over the second reactor and the downstream reactors, and the reactants are allowed to react together during a residence time of from 0.5 to 8 hours. The above copolymers can be used as incrustation inhibitors or for scaling inhibition.
|
