| abstract |
The invention relates to a method for producing (poly-C<SUB>2</SUB>-C<SUB>4</SUB> alkylene glycol)-monoacrylic esters and -monomethacrylic esters, and to a method for producing copolymers of such (poly-C<SUB>2</SUB>-C<SUB>4</SUB> alkylene glycol)-mono(meth)acrylic esters with acrylic ester or methacrylic ester and to the use of the polymers as liquefying additives in cement-containing preparations. The (poly-C<SUB>2</SUB>-C<SUB>4</SUB> alkylene glycol)-monoacrylic esters and -monomethacrylic esters are produced by reacting acrylic anhydride or methacrylic anhydride (referred to in the following as (meth)acrylic anhydride (A)) with at least one OH group-carrying poly-C<SUB>2</SUB>-C<SUB>4</SUB> alkylene glycol compound (P) in the presence of a base, said base being selected from the group of basic compounds that have, at 90° C, a solubility in the poly-C<SUB>2</SUB>-C<SUB>4</SUB> alkylene glycol compound (P) of not more than 10 g/l, the molar ratio of (meth)acrylic anhydride (A) to compound (P) (molar ratio (A):(P)) being in the range of from 1:1 to 1.095:1, preferably in the range of from 1.005:1 to 1.09:1, especially in the range of from 1.01:1 to 1.085:1 and most preferred in the range of from 1.02:1 to 1.08:1. The production of (meth)acrylic acid with (poly-C<SUB>2</SUB>-C<SUB>4</SUB> alkylene glycol)-mono(meth)acrylic esters comprises the following steps: i) production of a (poly-C<SUB>2</SUB>-C<SUB>4</SUB> alkylene glycol)mono(meth)acrylic ester by reacting (meth)acrylic anhydride (A) with at least one OH group-carrying poly-C<SUB>2</SUB>-C<SUB>4</SUB> alkylene glycol compound (P) in the presence of a base according to the inventive method, and ii) radical copolymerization of the (poly-C<SUB>2</SUB>-C<SUB>4</SUB> alkylene glycol)mono(meth)acrylic ester obtained in step i) with acrylic acid and/or methacrylic acid and optionally additional ethylenically unsaturated monomers. |