PROCESS FOR LOW-CONCENTRATION, INVERSE EMULSION POLYMERIZATION OF WEAKLY NEUTRALIZED POLYMERS AND INVERSE EMULSIONS OBTAINED

• US 20140309368A1
• Filed: 02/11/2014
• Published: 10/16/2014
• Est. Priority Date: 02/21/2013
• Status: Active Grant

• Current Assignee: SPCM SA
• Original Assignee: SPCM SA
• Inventors: Champagnon, Lionel, BLONDEL, Frederic
• Granted Patent: US 9,290,588 B2
• Time in Patent Office: Days
• US Class Current: 524/801
• CPC Class Codes: C08F 2/32 Polymerisation in water-in-oil emulsions
• CPC Class Codes: C08F 20/06 Acrylic acid; Methacrylic acid; Metal salts or ammonium salts thereof
• CPC Class Codes: C08F 220/06 Acrylic acid; Methacrylic acid; Metal salts or ammonium salts thereof

Abstract

The present invention relates to a process for preparing a polymer by polymerization of an aqueous solution of one or more monomers in water-in-oil inverse emulsion, in which one or more of the monomers used comprise(s) at least one acid function, the molar percentage of monomers bearing at least one weak acid function relative to all the monomers used being at least 30%, wherein:

• • i) the polymerization is carried out with a concentration of all the monomers in aqueous solution which falls within the range of from 1.3 mmol to 3.6 mmol per gram of aqueous solution,
  • ii) during the polymerization, at most 20% of the acid functions present on the monomers which have at least one acid function are in neutralized form,
    and also to the polymers which can be obtained by means of such a process.

Claims

1. - A process for preparing a polymer by polymerization of an aqueous solution of one or more monomers in water-in-oil inverse emulsion, in which one or more of the monomers used comprise(s) at least one acid function, the molar percentage of monomers bearing at least one weak acid function relative to all the monomers used being at least 30%, wherein:

i) the polymerization is carried out with a concentration of all the monomers in aqueous solution which falls within the range of from 13 mmol to 3.6 mmol per gram of aqueous solution,

ii) during the polymerization, at most 20% of the acid functions present on the monomers which have at least one acid function are in neutralized form.

2. - The process as claimed in claim 1, wherein, during the polymerization, at most 10%, preferably at most 5%, and preferentially at most 2%, of the acid functions present on the monomers which have at least one acid function are in neutralized form.

3. - The process as claimed in claim 1, wherein all the acid functions present on the monomers are in free acid form during the polymerization.

4. - The process as claimed in claim 1, wherein the polymerization is carried out with a concentration of all the monomers in aqueous solution which falls within the range of from 1.7 to 3.3 mmol per gram of aqueous solution.

5. - The process as claimed in claim 1, wherein the molar percentage of monomers bearing one or more weak acid function(s) relative to all the monomers used which bear an acid function is at least 50%, preferentially at least 70%, and very preferentially at least 80%.

6. - The process as claimed in claim 1, wherein all the monomers used are monomers which have at least one ethylenic unsaturation.

7. - The process as claimed in claim 1, wherein the monomer bearing at least one weak acid function, in free acid form, is chosen from acrylic acid, methacrylic acid, itaconic acid, crotonic acid, maleic acid and fumaric acid, acrylic acid being preferred.

8. - The process as claimed in claim 1, wherein the polymerization is carried out with at least one neutral monomer chosen from acrylamide, methacrylamide, N,N-dimethylacrylamide, N-vinylmethylacetamide, N-vinylformamide, vinyl acetate, diacetone acrylamide, N-isopropylacrylamide, N-[2-hydroxy-1,1-bis(hydroxymethyl)ethyl]propenamide, (2-hydroxyethyl) acrylate, (2,3-dihydroxypropyl) acrylate, methyl methacrylate, (2-hydroxyethyl) methacrylate, (2,3-dihydroxypropyl) methacrylate and vinylpyrrolidone.

9. - The process as claimed in claim 1, wherein all the monomers used which bear at least one acid function are monomers bearing one or more weak acid function(s).

10. - The process as claimed in claim 9, wherein the polymerization is carried out with a mixture of acrylic acid/acrylamide monomers, with a degree of neutralization of the acid functions, wherein at most 20% of the acid functions present on the monomers, which have at least one acid function are in neutralized form, preferably at most 10% or 5% or 2%, or wherein all of the acid functions present on the monomers are in free acid form during polymerization.

11. - The process as claimed in claim 1, wherein the polymerization is carried out with at least one monomer bearing one or more strong acid function(s).

12. - The process as claimed in claim 11, wherein the polymerization is carried out with a molar percentage of monomers bearing one or more strong acid function(s) relative to all the monomers used of less than 50%, and preferentially of less than 30%.

13. - The process as claimed in claim 11, wherein the monomer bearing one or more strong acid function(s), in free acid form, is chosen from acrylamidoalkylsulfonic acids, such as 2-acrylamido-2-methylpropanesulfonic acid.

14. - The process as claimed in claim 10, wherein the polymerization is carried out with a mixture of 2-acrylamido-2-methylpropanesulfonic acid/acrylic acid monomers or a mixture of 2-acrylamido-2-methylpropanesulfonic acid/acrylic acid/acrylamide monomers, with a degree of neutralization of the acid functions.

15. - The process as claimed in claim 1, wherein the aqueous phase contains at least one monomer acting as a branching agent, such that the polymerization results in a crosslinked polymer.

16. - The process as claimed in claim 15, wherein the branching agent is chosen from methylenebisacrylamide (MBA), ethylene glycol diacrylate, polyethylene glycol dimethacrylate, diacrylamide, cyanomethyl acrylate, vinyloxyethyl acrylate, vinyloxy methacrylate, triallylamine, formaldehyde, glyoxal, glycidyl ethers such as ethylene glycol diglycidyl ether, and epoxies, and mixtures thereof.

17. - The process as claimed in claim 1, wherein the polymerization reaction is carried out in the presence of a water-in-oil emulsifier.

18. - The process as claimed in claim 1, wherein a step of neutralization of at least one part of the free acid functions present on the polymer is carried out, after polymerization.

19. - The process as claimed in claim 1, which uses a transfer agent chosen from methanol, isopropyl alcohol, sodium hypophosphite, 2-mercaptoethanol and sodium methallyl sulfonate, and mixtures thereof.

20. - The process as claimed in claim 1, which comprises the following steps:

a) providing an aqueous solution of the monomer(s) selected, termed aqueous phase,

b) emulsifying said aqueous solution in a water-immiscible phase, termed oil phase,

c) carrying out the polymerization reaction.

21. - The process as claimed in claim 20, wherein the weight ratio of the aqueous phase to the oil phase is from 50/50 to 90/10.

22. - The process as claimed in claim 20, wherein the oil phase is composed of a mineral oil containing saturated hydrocarbons of paraffinic, isoparaffinic, cycloparaffinic or naphthyl type having, at ambient temperature, a density of between 0.7 and 0.9;

of a vegetable oil;

of a synthetic oil such as hydrogenated polydecene or hydrogenated polyisobutene;

of one or more esters such as octyl stearate or butyl oleate;

of a vegetable oil such as squalane of vegetable origin;

or of a mixture of several of these oils.

23. - The process as claimed in claim 20, wherein the oil phase in which the aqueous solution is emulsified contains a water-in-oil emulsifier.

24. - The process as claimed in claim 20, wherein the polymerization reaction of step c) is initiated by introducing into the emulsion formed in step b) a free radical initiator.

25. - The process as claimed in claim 1, wherein, after the polymerization, one or more oil-in-water emulsifiers are introduced.

26. - The process as claimed in claim 1, wherein, after the polymerization reaction, the emulsion obtained is diluted or concentrated.

27. - The process as claimed in claim 1, wherein a step of at least partial neutralization of the free acid functions present in the polymer obtained is carried out after the polymerization reaction.

28. - The process as claimed in claim 27, wherein the neutralization step results in a percentage of neutralized acid functions relative to all the acid functions present on the polymer of from 30% to 100%.

29. - A polymer in the form of a water-in-oil inverse emulsion obtained by means of the process as defined in claim 1.

30. - The polymer as claimed in claim 29, wherein at most 20% of the acid functions present are in neutralized form, preferably at most 10%, even more preferably at most 5%, and preferentially at most 2%.

31. - The polymer as claimed in claim 30, subsequently subjected to a neutralization step resulting in a percentage of neutralized acid functions relative to all the acid functions present on the polymer of from 30% to 100%.

32. - The polymer as claimed in claim 29, which is branched or crosslinked.

33. - The polymer as claimed in claim 29, subsequently subjected to an isolation step so as to be in the form of a powder.

34. - The polymer as claimed in claim 33, wherein the isolation step is chosen from precipitation, azeotropic distillation and spray-drying techniques.

35. - The polymer as claimed in claim 29, which is water-soluble or water-swelling.