Aqueous solution of cationic copolymers derived from acrylamide, preparation method and use

Patent metadata

Field	Value
Publication number	US-9725532-B2
Application number	US-201515104018-A
Country	US
Kind code	B2
Filing date	Jan 15, 2015
Priority date	Jan 15, 2014
Publication date	Aug 8, 2017
Grant date	Aug 8, 2017

Abstract

The present invention relates to a process for the preparation of an aqueous polymer solution containing at least one cationic or amphoteric (co)polymer, comprising the following steps:
Hofmann degradation reaction on a (co)polymer based on at least one non-ionic monomer chosen from the group including acrylamide, methacrylamide, N,N-dimethylacrylamide, and acrylonitrile; post-processing of the resulting aqueous polymer solution of viscosity V1; characterized in that the post processing comprises the following successive steps: obtaining of an aqueous polymer solution containing at least one cationic or amphoteric (co)polymer derived from the Hofmann degradation reaction; post-processing of this aqueous polymer solution; characterized in that the post processing comprises the following successive steps:
(a) adjustment of the pH of the aqueous polymer solution to a value greater than or equal to 5.5; (b) decrease of the pH of the aqueous polymer solution to a value between 2 and 5.

The invention also concerns the use of this polymer solution as a flocculant, retention and/or drainage agent, and dry strength resistance in a paper manufacturing process.

First claim

The invention claimed is:

1. A process for the preparation of an aqueous polymer solution containing at least one cationic or amphoteric (co)polymer, said process comprising the following steps:
performing Hofmann degradation reaction, in aqueous solution, in the presence of an earth alkaline and/or alkaline hydroxide and an earth alkaline and/or alkaline hypohalite on a (co)polymer base of at least one non-ionic monomer chosen from the group consisting of acrylamide, methacrylamide, N,N-dimethylacrylamide, and acrylonitrile;
obtaining an aqueous polymer solution of V1 viscosity containing at least one cationic or amphoteric (co)polymer derived from the Hofmann degradation reaction; and
post-processing of the aqueous polymer solution;
wherein the post processing comprises the following successive steps:
(a) adjusting the pH of the aqueous polymer solution to a value greater than or equal to 5.5; and
(b) lowering the pH of the aqueous polymer solution to a value between 2 and 5.

2. The method according to claim 1 , wherein the adjusting step (a) comprises:
measuring the V1 viscosity of the aqueous polymer solution; then
adjusting the pH to a value greater than or equal to 5.5 and increasing the V1 viscosity of the aqueous polymer solution up to a V2 value corresponding to at least 1.5 times the V1 value while being less than 100,000 mPa·s.

3. The method according to claim 2 , wherein the V2 viscosity is greater than or equal to 2 times the V1 viscosity.

4. The method according to claim 3 , wherein the V2 viscosity of the aqueous polymer solution is less than 50,000 mPa·s.

5. The method according to claim 4 , wherein, in lowering step (b), the pH is lowered to a value of between 3 and 4.

6. The method according to claim 5 , wherein the pH of the aqueous polymer solution on which the post-processing is carried is between 2 and 5 prior to post-processing.

7. The method according to claim 5 , wherein the concentration of the aqueous polymer solution on which post processing is carried out varies between 0.5% and 50% by weight of (co)polymer compared to the weight of the aqueous polymer solution.

8. The method according to claim 7 , wherein, following said post-processing, (co)polymers in the polymeric solution consist of (co)polymers that are solely and directly from the Hofmann degradation of a (co)polymer base.

9. The method according to claim 2 , wherein the V2 viscosity of the aqueous polymer solution is less than 50,000 mPa·s.

10. The method according to claim 2 , wherein, in step (b), the pH of the aqueous polymer solution is lowered to between 2 and 5, and its viscosity decreased to a value V3, greater than V1 and less than V2.

11. The method according to claim 1 , wherein, in lowering step (b), the pH is lowered to a value of between 3 and 4.

12. The method according to claim 11 , wherein the pH of the aqueous polymer solution on which the post-processing is carried is between 2 and 5 prior to post-processing.

13. The method according to claim 1 , wherein the concentration of the aqueous polymer solution on which post processing is carried out varies between 0.5% and 50% by weight of (co)polymer compared to the weight of the aqueous polymer solution.

14. The method according to claim 1 , wherein, following said post-processing, (co)polymers in the polymeric solution consist of (co)polymers that are solely and directly from the Hofmann degradation of a (co)polymer base.

15. The method according to claim 1 , wherein, in step (a), the pH is adjusted by the addition of at least one compound selected from the group consisting of alkali hydroxides, earth alkaline hydroxides, ammonia, and quicklime.

16. The method according to claim 1 , wherein, in step (b), the pH is lowered by the addition of at least one compound selected from the group consisting of hydrochloric acid, sulfuric acid and nitric acid.

17. The method according to claim 1 , wherein the (co)polymer base used contains:
a. at least 5 mole % of at least one non-ionic monomer selected from the group consisting of acrylamide, methacrylamide, N,N-dimethylacrylamide, and acrylonitrile,
optionally up to 95 mole % of at least:
b. a cationic non saturated ethylene monomer, selected from the group consisting of monomers of type dialkylaminoalkyl (meth)acrylamide, diallylamine, methyldiallylamine and their quaternary ammonium salt,
c. and/or at least one non-ionic monomer selected from the group consisting of N-vinyl acetamide, N-vinyl formamide, N-vinylpyrrolidone and vinyl acetate,
d. and/or at least one anionic monomer selected from the group consisting of (meth)acrylic acid, acrylamidomethylpropyl sulfonic acid, itaconic acid, maleic anhydride, maleic acid, methallyl sulfonic acid, vinylsulfonique acid, and their salts,
e. and/or at least one additional polyfunctional compound selected from the group including polyethylenimine, polyamine (primary or secondary), polyallylamine, functional thioether, polyols, epichlorohydrin polyamides (PAE), and polyamine amides (AAP).

18. The method according to claim 1 , wherein the (co)polymer base additionally contains at least one polyfunctional compound containing at least 3 heteroatoms selected from N, S, O, and P and with each at least one mobile hydrogen.

19. The method according to claim 1 , wherein, in step (a), the pH is adjusted to between 5.5 and 12.

20. A process comprising using the aqueous polymer solution prepared according to claim 1 as a flocculant, retention agent, drainage agent, or agent for dry strength resistance in a paper manufacturing process.

Assignees

• Spcm Sa

Inventors

• Hund René
• Auriant Christophe
• Mialon Laurent

Classifications

• D21H21/06

  Paper forming aids · CPC title

• C08F222/385

  Monomers containing two or more (meth)acrylamide groups, e.g. N,N'-methylenebisacrylamide · CPC title

• C08F226/02

  by a single or double bond to nitrogen · CPC title

• C08L39/00

  Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a single or double bond to nitrogen or by a heterocyclic ring containing nitrogen; Compositions of derivatives of such polymers · CPC title

• D21H21/18

  Reinforcing agents · CPC title