Anionic polymers of acrylic and/or methacrylic acids and maleic esters, and salts thereof, and their use as cement/concrete additives
View Patent ↗Anionic polymers obtainable by: (a) esterifying maleic acid or its anhydride with alkyl polyalkylene glycols; (b) copolymerizing the esters obtained with (meth)acrylic acid; and (c) converting the polymers obtained into the salt form by addition of alkali metal bases; are disclosed.
1. An alkali metal salt of a copolymer of a maleic ester and a comonomer selected from the group consisting of acrylic acid, methacrylic acid and mixtures thereof, wherein the maleic ester comprises an esterification product of a component selected from the group consisting of maleic acid and maleic anhydride with an alkyl polyalkylene glycol, wherein the alkyl polyalkylene glycol corresponds to the general formula (I):
R 1 (OCHCHR 2 ) n OH (I)
wherein R 1 represents an alkyl group having from 1 to 4 carbon atoms, each R 2 represents a hydrogen or a methyl group and n represents a number of from 1 to 40; and wherein the salt of the copolymer has an average molecular weight of from 1,000 to 5,000 daltons.
2. The alkali metal salt of a copolymer according to claim 1 , wherein the maleic ester comprises an esterification product of maleic anhydride and methyl polyethylene glycol.
3. A process for preparing an anionic polymer, said process comprising:
(a) esterifying a component selected from the group consisting of maleic acid and maleic anhydride with an alkyl polyalkylene glycol to form a maleic ester, wherein the alkyl polyalkylene glycol corresponds to the general formula (I):
R 1 (OCHCHR 2 ) n OH (I)
wherein R 1 represents an alkyl group having from 1 to 4 carbon atoms, each R 2 represents a hydrogen or a methyl group and n represents a number of from 1 to 40;
(b) copolymerizing the maleic ester with a comonomer selected from the group consisting of acrylic acid, methacrylic acid and mixtures thereof to form a polymer; and
(c) neutralizing the polymer with an alkali metal base;
wherein the polymer has an average molecular weight of from 1,000 to 5,000 daltons.
4. The process according to claim 3 , wherein R 1 represents a methyl group and each R 2 represents a hydrogen.
5. The process according to claim 3 , wherein the alkyl polyalkylene glycol has an average molecular weight of from 200 to 2,000 daltons.
6. The process according to claim 3 , wherein the comonomer comprises methacrylic acid.
7. The process according to claim 3 , wherein the polymer is neutralized to a pH of from 6 to 8.
8. The process according to claim 4 , wherein the comonomer comprises methacrylic acid.
9. An anionic polymer prepared by the process according to claim 3 .
10. An anionic polymer prepared by the process according to claim 4 .
11. An anionic polymer prepared by the process according to claim 6 .
12. An anionic polymer prepared by the process according to claim 8 .
13. An aqueous solution of the anionic polymer according to claim 1 , having a solids content of from 40 to 50% by weight.
14. An aqueous solution of the anionic polymer according to claim 9 , having a solids content of from 40 to 50% by weight.
15. A uncured preparation comprising a component selected from the group consisting of cement and concrete, water, and the alkali metal salt of a copolymer according to claim 1 .
16. A uncured preparation comprising a component selected from the group, consisting of cement and concrete, water, and an anionic polymer according to claim 9 .
17. A method of retarding the set time of a cement or concrete preparation, said method comprising:
(a) providing a water-containing cement or concrete preparations; and
(b) combining the preparation with the alkali metal salt of a copolymer according to claim 1 .
18. A method of retarding the set time of a cement or concrete preparation, said method comprising:
(a) providing a water-containing cement or concrete preparations; and
(b) combining the preparation with the anionic polymer according to claim 9 .