Copolymer comprising oxazoline monomers and use thereof as crosslinker

1. A copolymer A, comprising:

at least one monomer (a) selected from the group consisting of a C 1-20 -alkyl (meth)acrylate, a C 8-20 -vinylaromatic, and a combination thereof;

at least one ethylenically unsaturated monomer (b), which comprises at least one sulfonic acid group (—SO 3 M), wherein M is one or more metals;

at least one ethylenically unsaturated monomer (c), which comprises at least one oxazoline group;

and optionally at least one further monomer (d) and/or additive,

wherein a fraction of the monomers (b) and (c) is in total less than 50% by weight, based on the total amount of the monomers in the copolymer A, and

wherein the copolymer A is a water-soluble polymer having a solubility in water of at least 100 g/l.

2. The copolymer according to claim 1 , wherein the fraction of the monomers (b) and (c) is in total 2 to 49.9% by weight, based on the total amount of the monomers in the copolymer A.

3. The copolymer according to claim 1 , wherein the copolymer A comprises exclusively the monomers (b) and (c) as water-soluble monomers.

4. The copolymer according to claim 1 , wherein the copolymer A comprises, as the monomer (a), 50 to 98% by weight, based on the total amount of the monomers in the copolymer A, of at least one monomer of a C 1-8 -alkyl (meth)acrylate.

5. The copolymer according to claim 1 , wherein the monomer (b) is a compound of the formula (II)

H 2 C═C(R 1 )C(═O)—NH—Z—SO 3 M  (II),

where:

R 1 is H or methyl;

Z is a divalent linking group which is selected from the group consisting of a bond, C 1-10 -alkylene, phenylene and C 1-10 -alkylphenylene;

and M is one or more metals.

6. The copolymer according to claim 1 , wherein the monomer (c) is a compound according to formula (IV)

where:

R is a C 2-20 -alkenyl radical comprising at least one ethylenically unsaturated group; and

R 3 , R 4 , R 5 , R 6 are selected independently of one another from the group consisting of H, halogen, C 1-20 -alkyl, C 2-20 -alkenyl, C 6-20 -aryl, C 7-32 -arylalkyl, C 1-20 -hydroxyalkyl, C 1 - 20 -aminoalkyl and C 1-20 -haloalkyl.

7. The copolymer according to claim 6 , wherein the radicals R 3 , R 4 , R 5 , R 6 , independently of one another, are H or C 1-6 -alkyl.

8. The copolymer according to claim 1 , wherein the copolymer A comprises

50 to 98% by weight of the at least one monomer (a);

1 to 45% by weight of the at least one monomer (b);

1 to 45% by weight of the at least one monomer (c); and

0 to 10% by weight of the at least one further monomer (d) and/or additive.

9. The copolymer according to claim 1 , wherein the copolymer A comprises

50 to 98% by weight of the at least one monomer (a), where the monomer (a) is at least one C 1-12 -alkyl (meth)acrylate;

1 to 45% by weight of the at least one monomer (b), where the monomer (b) is a monoethylenically unsaturated monomer which comprises precisely one sulfonic acid group;

1 to 45% by weight of the at least one monomer (c), where the monomer (c) is at least one monomer selected from the group consisting of 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline,2-vinyl-5-methyl-2-oxazoline, 2-vinyl-4-ethyl-2-oxazoline, 2-vinyl-4,4-dimethyl-2-oxazoline, 2-vinyl-5,5-dimethyl-2-oxazoline, 2-vinyl-4,4,5,5-tetramethyl-2-oxazoline, 2-isopropenyl-2-oxazoline, 2isopropenyl -4-methyl-2-oxazoline, 2-isopropenyl-5-methyl-2-oxazoline, 2-isopropenyl-4-ethyl-2-oxazoline, 2-isopropenyl-5-ethyl-2-oxazoline, 2-isopropenyl-4,4-dimethyl-2-oxazoline, 2-isopropenyl-5,5-dimethyl-2-oxazoline and 2-isopropenyl-4,4,5,5-tetramethyl-2-oxazoline, and

0 to 10% by weight of the at least one further monomer (d) and/or additive.

10. A process for preparing the copolymer A according to claim 1 , the process comprising:

polymerizing at least one monomer (a) selected from the group consisting of a C 1-20 -alkyl (meth)acrylate, a C 8-20 -vinylaromatic, and a combination thereof; at least one ethylenically unsaturated monomer (b), which comprises at least one sulfonic acid group (—SO 3 M); at least one ethylenically unsaturated monomer (c), which comprises at least one oxazoline group; and optionally at least one further monomer.

11. The process according to claim 10 , wherein the monomers (a), (b), (c) and optionally (d) are free-radically polymerized, where the free-radical polymerization is carried out as solution polymerization.

12. A method for crosslinking a polyfunctional polymer P comprising at least two functional groups selected from the group consisting of a carboxy group, a phosphoric acid group, a phenolic hydroxy group, and an aromatic thiol group, the method comprising:

adding at least one copolymer A according to claim 1 to the polyfunctional polymer P.

13. A composition, comprising:

i) at least one copolymer A according to claim 1 ;

ii) at least one polyfunctional polymer P comprising at least two functional groups selected from the group consisting of a carboxy group, a phosphoric acid group, a phenolic hydroxy group, and an aromatic thiol group; and

iii) at least one volatile, basic compound.

14. A method of producing an adhesive, a sealant, a synthetic resin render, a paper coating slip, a fiber nonwoven, a flexible roof coating, or a paint, the method comprising:

adding a binder comprising the composition according to claim 13 .

15. A method for consolidating sand, comprising:

adding a binder comprising the composition according to claim 13 .

16. A method for producing a textile or leather auxiliary, an impact modifier, mineral binder, or a plastic, comprising:

adding the composition according to claim 13 .