# US 9,751,958 B2 · Use of heating steam condensate for producing water-absorbent polymer particles

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- Number: US 9,751,958 B2
- Document ID: US9751958B2
- Status: Granted
- Kind: B2
- Application number: 13/498,364
- Filed: 2010-10-05
- Published: 2012-08-09
- Granted: 2017-09-05
- Earliest claimed: 2009-10-09
- Assignees: BASF SE
- Applicants: Rüdiger Funk; Jürgen Schröder
- Inventors: Rüdiger Funk; Jürgen Schröder
- Web page: https://patentgrep.com/patent/US9751958B2

## CPC

- C08F 2/18: Suspension polymerisation
- A61L 15/22: containing macromolecular materials
- C08F 2/00: Processes of polymerisation
- C08F 220/06: Acrylic acid; Methacrylic acid; Metal salts or ammonium salts thereof
- C08F 222/102: {of dialcohols, e.g. ethylene glycol di(meth)acrylate or 1,4-butanediol dimethacrylate}
- C08F 222/103: {of trialcohols, e.g. trimethylolpropane tri(meth)acrylate}
- C08F: MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- A61L: METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES (preservation of bodies or disinfecting characterised by the agents employed A01N; preserving, e.g. sterilising, food or foodstuffs A23; preparations for medical, dental or toiletry purposes A61K)

## Abstract

The present invention relates to a process for producing water-absorbing polymer particles, wherein an aqueous monomer solution is polymerized and the monomer solution is prepared using steam condensate.

## Claims

### Claim 1

A process for producing water-absorbing polymer particles, comprising preparing an aqueous monomer solution or suspension by mixing
a) at least one ethylenically unsaturated monomer bearing an acid group,
b) optionally a neutralizing agent,
c) water at least partly as a steam condensate and the steam condensate comprises less than 1 ppm of dissolved oxygen, and
d) at least one crosslinker,
then inertizing the monomer solution or suspension, polymerizing the inertized monomer solution or suspension, then drying the resulting polymer gel, grinding, and classifying,
wherein the steam condensate is obtained from the condensation of steam in heat exchangers used for drying air in forced air belt dryers in the drying step.

### Claim 2 (depends on 1)

The process according to claim 1, wherein the water c) is steam condensate to an extent of at least 50% by weight.

### Claim 3 (depends on 1)

The process according to claim 1, wherein the oxygen content of the aqueous monomer solution or suspension is lowered below 1 ppm by inertization.

### Claim 4 (depends on 1)

The process according to claim 1, wherein the monomer a) is acrylic acid partly neutralized to an extent of at least 50 mol %.

### Claim 5 (depends on 1)

The process according to claim 1, wherein the monomer a) has been neutralized to an extent of 25 to 85 mol %.

### Claim 6 (depends on 1)

The process according to claim 1, wherein the steam condensate comprises less than 0.5 ppm of dissolved oxygen.

### Claim 7 (depends on 1)

The process according to claim 1, wherein the steam condensate comprises less than 0.1 ppm of dissolved oxygen.

### Claim 8 (depends on 1)

The process according to claim 1, wherein the water c) is steam condensate to an extent of at least 90% by weight.

### Claim 9 (depends on 1)

The process according to claim 1, wherein the water c) is steam condensate to an extent of at least 95% by weight.