Method for producing polymers on the basis of acryloyldimethyltaurate, neutral monomers, and monomers with carboxylate groups

1. A process for preparing a water-soluble or water-swellable polymer containing

a) 5 to 79.99 mol %, of at least one repeat structural unit of the formula (1)

in which

R 1 , R 2 , R 3 is hydrogen, methyl or ethyl,

Y is a chemical bond, O, CH 2 , C(CH 3 )H, C(O)O, C(O), C(O)NR 2 ,

A is a chemical bond, O, arylene, phenylene, linear or branched C 1 -C 12 -alkylene, a linear monohydroxyalkylene group having 2 to 6 carbon atoms or a linear or branched dihydroxyalkylene group having 3 to 6 carbon atoms,

D is S(O), POH, POR 3 or PO − Q + ,

Q + is H + , Li + , Na + , K + , ½ Ca ++ , ½ Mg ++ , ½ Zn ++ , ⅓ Al +++ , ¼ Zr ++++ or is mixtures of these ions,

b) 20 to 75 mol %, of at least one mutually independent uncharged repeat structural unit, and

c) 0.01 to 20 mol %, of at least one further anionic repeat structural unit that have originated from at least one monomer having at least one carboxylate group,

wherein the process comprises the step of subjecting monomers from which the structural units a) to c) derive to precipitative free-radical polymerization in a polar solvent or solvent mixture, wherein the polar solvent or solvent mixture comprises water, 2-methylpropan-2-ol and dimethyl ketone, with the proviso that the water content of the solvent does not exceed 10% by weight.

2. The process as claimed in claim 1 , wherein the structural unit of the formula (1) are derived from monomers selected from the group consisting of acryloyldimethyltaurate, acryloyl-1,1-dimethyl-2-methyltaurate, acryloyltaurate, acryloyl-N-methyltaurate, vinylsulfonic acid, styrenesulfonic acid, 3-allyloxy-2-hydroxy-1-propanesulfonic acid, vinylphosphonic acid, and 2-acrylamido-2-methylpropanephosphonic acid.

3. The process as claimed in claim 1 , wherein the neutralization level of the structural unit of the formula (1) is from 50.0 to 100 mol %.

4. The process as claimed in claim 1 , wherein the structural unit b) is at least one monomer selected from the group consisting of N-vinylformamide, N-vinylacetamide, N-methyl-N-vinylformamide, N-methyl-N-vinylacetamide, N-vinyl-2-pyrrolidone, N-vinylcaprolactam, vinyl acetate, N,N-dimethylacrylamide, N-isopropylacrylamide, acrylamide, and methyl acrylate.

5. The process as claimed in claim 1 , wherein the structural unit c) derive from monomers of the formula (5)

where

R 14 , R 15 is hydrogen, methyl or ethyl, C(O)O − Z + ,

X, Y 3 is a chemical bond, O, CH 2 , C(O)O, OC(O), C(O)NR 15 or NR 15 C(O),

M is a chemical bond, —[C(O)O—CH 2 —CH 2 ] q —, a linear or branched alkylene group having 1 to 6 carbon atoms, a linear or branched, mono- or polyunsaturated alkenylene group having 2 to 6 carbon atoms, a linear monohydroxyalkylene group having 2 to 6 carbon atoms or a linear or branched dihydroxyalkylene group having 3 to 6 carbon atoms,

q is an integer from 1-5 and

Z+ is H+, Li+, Na+, K+, Zr+, ½ Ca++, ½ Mg++, ½ Zn++, ⅓ Al+++, ¼ Zr++++ or is mixtures of these ions.

6. The process as claimed in claim 1 , wherein the structural unit c) is derived from at least one monomer selected from the group consisting of acrylic acid, methacrylic acid, itaconic acid, carboxyethyl acrylate, carboxyethyl acrylate oligomers, 2-propylacrylic acid and 2-ethylacrylic acid and the respective alkali metal or alkaline earth metal salts thereof.

7. The process as claimed in claim 1 , wherein the monomers from which the structural units of components a) and c) derive are neutralized prior to the polymerization, or the polymer is neutralized after the polymerization, with a base selected from the group consisting of sodium hydrogencarbonate, sodium carbonate, sodium hydroxide, potassium hydrogencarbonate, potassium carbonate, potassium hydroxide, lithium hydrogencarbonate, lithium carbonate, lithium hydroxide, calcium hydrogencarbonate, and calcium carbonate.

8. The process as claimed in claim 1 , wherein the solvent comprises at least one polar organic solvent selected from the group consisting of methanol, ethanol, 1-propanol, 2-propanol, 2-methyl-2-propanol, 1-butanol, 2-butanol, dimethyl ketone, diethyl ketone, tetrahydropyran, tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxane, 1,4-dioxane, and mixtures thereof.

9. The process as claimed in claim 1 , wherein the polar solvent comprises 0.5% to 10% by weight of water, 1% to 98.5% by weight of 2-methylpropan-2-ol and 1% to 98.5% by weight of dimethyl ketone.

10. The process as claimed in claim 1 , wherein the polar solvent comprises 1% to 5% by weight of water, 7.5% to 91.5% by weight of 2-methylpropan-2-ol and 7.5% to 91.5% by weight of dimethyl ketone.

11. The process as claimed in claim 1 , wherein the polar solvent is separated from the product after the polymerization process by a filtration or distillation.

12. A water-soluble or water-swellable polymer prepared by the process as claimed in claim 1 , wherein the water-soluble or water-swellable polymer has a k value of 100 to 300.

13. A drilling mud comprising at least one water-soluble or water-swellable polymer as claimed in claim 12 .

14. A cement slurry for cementing a deep well, comprising at least one water-soluble or water-swellable polymer as claimed in claim 12 .