US 5,492,962 AGranted

Method for producing compositions containing interparticle crosslinked aggregates

AssigneeThe Procter & Gamble Company

InventorsFrank H. Lahrman, Donald C. Roe, Charles J. Berg

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Abstract

Methods of producing particulate, absorbent, polymeric compositions comprising interparticle crosslinked aggregates. In the methods of the present invention, an interparticle crosslinking agent is applied onto precursor particles; the precursor particles are physically associated to form a multiplicity of aggregates; and the interparticle crosslinking agent is reacted with the polymer material of the precursor particles of the aggregates, while maintaining the physical association of the precursor particles, to form crosslink bonds between the precursor particles to form interparticle crosslinked aggregates. The interparticle crosslinked aggregates are formed to such an extent that the mass average particle size of the polymeric composition is at least about 25% greater than the mass average particle size of the precursor particles.

Claims24

Dependent claims

A method for producing a particulate, absorbent, polymeric composition comprising interparticle covalently crosslinked aggregates, said method comprising the steps of:

(a) providing substantially dry precursor particles of substantially water-insoluble, absorbent, hydrogel-forming, polymer material;
said polymer material of said precursor particles being a slightly network crosslinked product of a polymer selected from the group consisting of hydrolyzed starch/acrylonitrile graft copolymer, partially neutralized starch/acrylonitrile acid graft copolymer, starch-acrylic acid graft copolymer, partially neutralized starch-acrylic acid graft copolymer, saponified vinyl acetate-acrylic ester copolymers, hydrolyzed acrylonitrile or acrylamide copolymers, and partially neutralized polyacrylic acid;
(b) applying (i) an interparticle crosslinking agent and (ii) 0.01 to about 60 parts by weight per 100 parts by weight of said precursor particles of water, a hydrophilic organic solvent, or a mixture thereof onto said precursor particles;
provided that when water is applied to said precursor particles it is used in a proportion of from about 0.1 parts to about 10 parts by weight per 100 parts by weight of the precursor particles;
said interparticle crosslinking agent being capable of reacting with said polymer material of said precursor particles;
said interparticle crosslinking agent being selected from the group consisting of polyhydric alcohol compounds, polyglycidyl ether compounds, polyfunctional aziridine compounds, polyfunctional amine compounds, or polyfunctional isocyanate compounds;
(c) forming a multiplicity of aggregates of said precursor particles;
and
(d) reacting said interparticle crosslinking agent with said polymer material of said precursor particles of said aggregates, while insuring minimal dissociation forces or stresses are introduced during the reaction step, to form covalent crosslink bonds between said precursor particles to form interparticle crosslinked aggregates, said interparticle crosslinked aggregates being present in the polymeric composition in an amount such that the polymeric composition has a mass average particle size at least about 25% greater than the mass average particle size of said precursor particles.

6 more elements

A method for producing a particulate, absorbent, polymeric composition comprising interparticle covalently crosslinked aggregates, the method comprising the steps of:

(a) providing substantially dry precursor particles of substantially water-insoluble, absorbent, hydrogel-forming, polymer material;
said polymer material consisting essentially of slightly network crosslinked products of partially neutralized polyacrylic acid;
(b) applying (i) an interparticle crosslinking agent and (ii) 0.01 to about 60 pads by weight per 100 parts by weight of said precursor particles of water, a hydrophilic organic solvent, or a mixture thereof onto said precursor particles;
provided that when water is applied to said precursor particles it is used in a proportion of from about 0.1 parts to about 10 parts by weight per 100 parts by weight of the precursor particles;
said interparticle crosslinking agent being selected from the group consisting of trimethylol propane, ethylene glycol, 1,2-propanediol, 1,3-propanediol, or glycerol;
(c) forming a multiplicity of aggregates of said precursor particles;
and
(d) heating said interparticle crosslinking agent and said aggregates to react said interparticle crosslinking agent with said polymer material of said precursor particles of said aggregates, while insuring minimal dissociation forces or stresses are introduced during the reaction step, to form covalent crosslink bonds between said precursor particles to form interparticle crosslinked aggregates, said interparticle crosslinked aggregates being present in the polymeric composition in an amount such that the polymeric composition has a mass average particle size at least about 30% greater than the mass average particle size of said precursor particles.

5 more elements

Dependencies are inferred from the claim text.

Facts

Application: 08/228,947Filed 18 Apr 1994 · continuation
Priority: 2 Apr 1990
Granted: 20 Feb 1996
Term ends: Not estimatedThe source records don’t support an estimate.

Classification2 codes

A61L 15/60
Use of materials characterised by their function or physical properties: liquid-swellable gel-forming materials, e.g. super-absorbents
A61L
Methods or apparatus for sterilising materials or objects in general