Superabsorbent carboxyl-containing polymers with odor control properties and method for preparation

• US 20070060691A1
• Filed: 06/26/2002
• Published: 03/15/2007
• Est. Priority Date: 06/29/2001
• Status: Abandoned Application

• Current Assignee: Evonik Degussa GmbH
• Original Assignee: Evonik Degussa GmbH
• Inventors: Kim, Young-Sam
• Application Number:
  US10/480,328
• Publication Number:
  US 20070060691A1
• Time in Patent Office: Days
• US Class Current: 524/423
• CPC Class Codes: A61L 15/46 Deodorants or malodour counteractants, e.g. to inhibit the formation of ammonia or bacteria
• CPC Class Codes: A61L 15/60 Liquid-swellable gel-forming materials, e.g. super-absorbents
• CPC Class Codes: A61L 2300/104 Silver, e.g. silver sulfadiazine
• CPC Class Codes: A61L 2300/404 Biocides, antimicrobial agents, antiseptic agents
• CPC Class Codes: C08K 3/015 Biocides macromolecular substances as carriers for biocide material A01N25/10
• CPC Class Codes: C08K 3/30 Sulfur-, selenium- or tellurium-containing compounds

Abstract

A water-absorbent, water-insoluble polymer comprising silver cations that are neither ion exchanged in a zeolite nor bonded in a water-insoluble inorganic phosphate.

Claims

1. A water-absorbent, water-insoluble polymer comprising silver cations that are neither ion exchanged in a zeolite nor bonded in a water-insoluble inorganic phosphate.

2. The polymer of claim 1 wherein the polymer is in the form of particles and is derived from one or more ethylenically unsaturated carboxyl-containing monomers and optionally one or more comonomers copolymerizable with the carboxyl-containing monomer.

3. The polymer of claim 2 wherein the carboxyl-containing monomer is selected from the group consisting of ethylenically unsaturated carboxylic acids, ethylenically unsaturated carboxylic acid anhydrides, salts of unsaturated carboxylic acids and mixtures thereof;

and the optional comonomer is selected from the group consisting of an acrylamide, a vinyl pyrrolidone, a vinyl sulphonic acid or a salt thereof, an acrylonitrile, a cellulosic monomer, a modified cellulosic monomer, a polyvinyl alcohol monomer and a starch hydrolyzate monomer.

4. The polymer of claim 2 wherein the amount of silver cations is from 1 to 10,000 ppm, based on the weight of dry polymer.

17. An absorbent structure comprising water-absorbent polymer of claims 1 or 16 and at least one of a woven or nonwoven structure of paper, synthetic fibers, natural fibers, or a combination of these.

5. A process for the preparation of a water-absorbent, water-insoluble polymer, the process comprising:

(I) polymerizing a polymerization mixture comprising;

(a) one or more ethylenically unsaturated carboxyl-containing monomers,

(b) one or more crosslinking agents,

(c) optionally one or more comonomers copolymerizable with the carboxyl-containing monomer, and

(d) a polymerization medium, to form a crosslinked hydrogel,

(II) comminuting the hydrogel to particles, and

(III) drying the hydrogel,

wherein a solution of a silver salt is added in at least one of the following steps;

(i) to the monomer mixture prior to the beginning of the polymerization or to the reaction mixture during polymerization, or

(ii) to the crosslinked hydrogel prior to or after comminution in step (II), or

(iii) to the dried polymer particles after step (III).

6. The process of claim 5 wherein the silver salt solution is added to the dried polymer particles after step (III).

7. The process of claim 5 wherein the silver salt is selected from the group consisting of silver nitrate, silver acetate, silver benzoate, silver bromate, silver chlorate, silver lactate, silver molybdate, silver nitrite, silver(I) oxide, silver perchlorate, silver permanganate, silver selenate, silver selenite, silver sulfadiazine, silver sulfate, and mixtures thereof.

8. The process of claim 5 wherein the silver salt is added in an amount providing 1 to 10,000 ppm silver cations, based on weight of dry polymer.

9. The process of claim 5 further comprising step (IV) wherein the dried polymer particles from step (III) are heated to a temperature of from 170 to 250°

C. for from 1 to 60 minutes prior to or after addition of the silver salt.

10. The process of claim 5 wherein the solution of the silver salt is an aqueous solution.

11. The process of claim 10 wherein the aqueous solution of the silver salt additionally comprises a polyether polyol.

12. The process of claim 6 wherein the dried polymer particles from step (III) are treated with an aqueous solution of aluminum sulfate prior to, simultaneously with or after the addition of the silver salt solution.

13. The process of claim 6 wherein fumed silica is mixed with the dried polymer particles from step (III) prior to or simultaneously with the addition of the silver salt solution.

14. The process of claim 13 wherein the fumed silica is employed as an aqueous dispersion.

15. The process of claim 6 further comprising addition of an additive selected from the group consisting of activated carbon, chlorophyllin, chelating agents, soda, sodium bicarbonate, copper sulfate, copper acetate, zinc sulfate, silicates, fumed silica, silica, clay, cyclodextrin, citric acid, chitosan, ion exchange resin particles, zeolites or combinations thereof, prior to, simultaneously with or after the addition of the silver salt solution.

16. The water-absorbent, water insoluble polymer prepared by the process of claim 5.

18. An absorbent structure comprising silver ions and at least one of a woven or nonwoven structure of paper, synthetic fibers, natural fibers, or a combination of these.

19. A process for the preparation of a water-absorbent, water-insoluble polymer, the process comprising:

(I) polymerizing a polymerization mixture comprising;

(a) one or more ethylenically unsaturated carboxyl-containing monomers,

(b) one or more crosslinking agents,

(c) optionally one or more comonomers copolymerizable with the carboxyl-containing monomer, and

(d) a polymerization medium, to form a crosslinked hydrogel,

(II) comminuting the hydrogel to particles, and

(III) drying the hydrogel,

wherein from 100 to 1,000 ppm of a silver salt are added to the process such that there is formed a polymer comprising silver cations.