Water absorbing agent and method for the production thereof

• US 20050245684A1
• Filed: 08/25/2003
• Published: 11/03/2005
• Est. Priority Date: 08/26/2002
• Status: Abandoned Application

• Current Assignee: BASF AG (BASF SE)
• Original Assignee: BASF AG (BASF SE)
• Inventors: Riegel, Ulrich, Daniel, Thomas, Elliott, Mark, Weismantel, Matthias, Wendker, Martin
• Application Number:
  US10/523,913
• Publication Number:
  US 20050245684A1
• Time in Patent Office: Days
• US Class Current: 525/178
• CPC Class Codes: A61L 15/24 Macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds; Derivatives thereof A61L15/225 takes precedence
• CPC Class Codes: A61L 15/60 Liquid-swellable gel-forming materials, e.g. super-absorbents
• CPC Class Codes: C08J 2300/14 Water soluble or water swellable polymers, e.g. aqueous gels
• CPC Class Codes: C08J 3/245 Differential crosslinking of one polymer with one crosslinking type, e.g. surface crosslinking
• CPC Class Codes: C08L 2666/04 Macromolecular compounds according to groups C08L7/00 - C08L49/00, or C08L55/00 - C08L57/00; Derivatives thereof
• CPC Class Codes: C08L 33/02 Homopolymers or copolymers of acids; Metal or ammonium salts thereof
• CPC Class Codes: C08L 33/26 Homopolymers or copolymers of acrylamide or methacrylamide
• CPC Class Codes: C08L 39/04 Homopolymers or copolymers of monomers containing heterocyclic rings having nitrogen as ring member

Abstract

Described is a water absorbent comprising (a) particles of a water absorbent polymer, and (b) a nitrogenous polymer containing from 5 to 17 mol/kg, based on the total weight of the nitrogenous polymer, of protonatable nitrogen atoms. The water absorbent possesses an improved property profile featuring high absorptive capacity, improved fluid transmission and high wet strength.

Claims

1. A water absorbent comprising

(a) particles of a water absorbent polymer, and

(b) a nitrogenous polymer containing from 5 to 17 mol/kg, based on the total weight of the nitrogenous polymer, of protonatable nitrogen atoms.

2. The water absorbent of claim 1, wherein the nitrogenous polymer is a hydrolysis product of a homo- or copolymer of an N-vinylcarboxamide, and/or N-vinylcarboximide, or a mixture thereof.

3. The water absorbent of claim 1 having

a particle size distribution wherein more than 98% by weight of the particles are from 100 to 850 μ

m in size,

a Saline Flow Conductivity of at least 30×

10<sup>−

7</sup> cm³ s/g,

a Ball Burst Strength (30 min) of at least 50 gf,

a Ball Burst Strength (16 h) of at least 50 gf, and

a quotient [BBS (30 min)—

BBS (16 h)]/BBS (30 min) of less than 0.8.

4. The water absorbent of claim 2 wherein the nitrogenous polymer is a hydrolysis product of a homopolymer of N-vinylformamide having a degree of hydrolysis in the range from 30 to 80 mol %.

5. The water absorbent of claim 1 wherein the nitrogenous polymer has a weight average molecular weight in the range from 10 000 to 500 000 daltons.

6. The water absorbent of claim 1 comprising from 0.001% to 5% by weight of the nitrogenous polymer, based on the weight of the water absorbent polymer.

7. The water absorbent of claim 1 further comprising a finely divided water-insoluble salt.

8. The water absorbent of claim 1 wherein the water absorbent polymer is polymerized from

from 49.9% to 99.9% by weight of at least one monomer A selected from the group consisting of monoethylenically unsaturated acids and salts thereof,

from 0% to 50% by weight of at least one monoethylenically unsaturated monomer B other than said monomer A, and

from 0.001% to 20% by weight of at least one crosslinking monomer C.

9. The water absorbent claim 1 wherein the particles of the water absorbent polymer are surface postcrosslinked.

10. The water absorbent claim 1 further comprising a carrier selected from the group consisting of cellulose, modified cellulose, rayon, polypropylene, polyester, hydrophilicized nylon, polyethylene, polycarylic, polyamide, polystyrene, polyurethane, and polyacrylonitrile.

11. The water absorbent as claimed in claim 10 wherein the nitrogenous polymer is applied onto the carrier.

12. A process for producing a water absorbent of claim 1 comprising applying the nitrogenous polymer or a solution thereof onto the particles of the water absorbent polymer and, if necessary, drying the water absorbent.