US 5,629,377 A · Water absorbent resin particles of crosslinked carboxyl containing polymers and method of preparation

Abstract

A water-absorbent resin particles that exhibits a centrifuged absorption capacity of 26 g/g or greater, an absorption under load of 24 g/g or greater at 0.6 psi load. Other aspects of the invention are processes for the preparation of such water-absorbent resin particles which comprise the inclusion of chlorine or bromine containing oxidizing agent followed by the heat-treatment to produce particles with superior centrifuged absorption capacity in combination with high absorption under load at high load, and acceptable levels of residuals. These water-absorbent resin particles provide superior performance when incorporated into absorbent structures.

Claims20

Dependent claims

A water-absorbent resin particle comprising:

from 80 to 99.9 weight percent of a crosslinked carboxyl-containing polymer prepared by polymerizing a polymerization mixture which comprises:
(a) from 70 to 99.9 weight percent of one or more ethylenically unsaturated carboxyl containing monomers,
(b) from 0.1 to 5 weight percent of one or more crosslinking agents, and
(c) from 0 to 25 weight percent of one or more comonomers copolymerizable with the carboxyl containing monomer,
(d) from 10 to 2000 ppm by weight of a chlorine or bromine containing oxidizing agent,
wherein the weight percentages and ppm of the polymerization mixture are based on the total weight of (a), (b) and (c), wherein the oxidizing agent has been substantially uniformly distributed within the resin particle prior to heat-treatment, and wherein the resin particle has been heated at a temperature of from 170.degree. C. to 250.degree. C. for from 1 to 60 minutes.

3 more elements

A process for the preparation of water-absorbent resin particles which comprises:

(I) polymerizing a polymerization mixture comprising:
(a) from 70 to 99.9 weight percent of one or more ethylenically unsaturated carboxyl containing monomers,
(b) from 0.1 to 5 weight percent of one or more crosslinking agents,
(c) from 0 to 25 weight percent of one or more comonomers copolymerizable with the carboxyl containing monomer,
(d) an aqueous or nonaqueous polymerization medium, and
(e) from 10 to 2000 ppm by weight of a chlorine or bromine containing oxidizing agent
to form a crosslinked hydrogel wherein the weight percentages and ppm are based on the total weight of (a), (b) and (c);
(II) optionally, comminuting the hydrogel to particles;
(III) drying the hydrogel by substantially removing the polymerization medium to form resin;
(IV) optionally, comminuting the resin to particles;
(V) heating the particles at a temperature of from 170.degree. C. to 250.degree. C. for from 1 to 60 minutes.

8 more elements

A process for the preparation of water-absorbent resin particles which comprises:

(I) polymerizing a polymerization mixture comprising:
(a) from 70 to 99.9 weight percent of one or more ethylenically unsaturated carboxyl containing monomers,
(b) from 0.1 to 5 weight percent of one or more crosslinking agents,
(c) from 0 to 25 weight percent of one or more comonomers copolymerizable with the carboxyl containing monomer, and
(d) an aqueous or nonaqueous polymerization medium
to form a crosslinked hydrogel wherein the weight percentages are based on the total weight of (a), (b) and (c);
(II) optionally, comminuting the hydrogel to particles;
(III) applying to the hydrogel a chlorine or bromine containing oxidizing agent dispersed or dissolved in a liquid so that there is substantially uniformly distributed through the hydrogel particles from 10 to 2000 ppm by weight, based on the weight of (a), (b) and (c), of the chlorine or bromine containing oxidizing agent
(IV) drying the hydrogel by substantially removing the polymerization medium and the liquid to form resin;
(V) optionally, comminuting the resin particles;
(VI) heating the particles at a temperature of from 170.degree. C. to 250.degree. C. for from 1 to 60 minutes.

8 more elements

Dependencies are inferred from the claim text.

Water absorbent resin particles of crosslinked carboxyl containing polymers and method of preparation

Life of this patent

Water absorbent resin particles of crosslinked carboxyl containing polymers and method of preparation

Life of this patent

Abstract

Claims20