Superabsorbent polymers and method of manufacturing the same
First Claim
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1. Surface-crosslinked superabsorbent particles comprising:
- (i) about 50% to about 88%, by weight, of a superabsorbent polymer, said superabsorbent polymer comprising about 0.001% to about 5%, by weight, of a surface crosslinking agent;
(ii) about 12% to about 35%, by weight, of a clay, said clay present in the vicinity of surfaces of the superabsorbent particles; and
(iii) 0% to about 25%, by weight, of an inorganic network builder, said particles prepared by a method comprising the steps of;
(a) polymerizing one or more monomers capable of providing a superabsorbent absorbent polymer in the presence of an internal crosslinking monomer to form a superabsorbent polymer hydrogel;
(b) comminuting the superabsorbent polymer hydrogel to form superabsorbent polymer hydrogel particles;
(c) drying the superabsorbent polymer hydrogel particles of step (b) to provide dry superabsorbent particles;
(d) applying a mixture comprising a surface crosslinking agent and a clay to the surface of the superabsorbent particles of step (c) to provide surface-treated superabsorbent polymer particles; and
(e) then heating the surface-treated superabsorbent polymer particles for a sufficient time at a sufficient temperature to surface crosslink the surface-treated superabsorbent polymer particles and position the clay in the vicinity of the surfaces of the surface-crosslinked superabsorbent particles.
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Abstract
Surface-crosslinked superabsorbent polymer (SAP) particles having a clay in the vicinity of the surfaces of the SAP particles a clay are disclosed. The clay is added to SAP particles during surface crosslinking to substantially reduce the generation, and recycling, of SAP fines, and to provide SAP particles having an improved acquisition rate of fluids and an improved permeability of a fluid through the swollen SAP particles. Diaper cores and absorbent articles containing the surface crosslinked SAP particles also are disclosed.
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Citations
30 Claims
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1. Surface-crosslinked superabsorbent particles comprising:
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(i) about 50% to about 88%, by weight, of a superabsorbent polymer, said superabsorbent polymer comprising about 0.001% to about 5%, by weight, of a surface crosslinking agent;
(ii) about 12% to about 35%, by weight, of a clay, said clay present in the vicinity of surfaces of the superabsorbent particles; and
(iii) 0% to about 25%, by weight, of an inorganic network builder, said particles prepared by a method comprising the steps of;
(a) polymerizing one or more monomers capable of providing a superabsorbent absorbent polymer in the presence of an internal crosslinking monomer to form a superabsorbent polymer hydrogel;
(b) comminuting the superabsorbent polymer hydrogel to form superabsorbent polymer hydrogel particles;
(c) drying the superabsorbent polymer hydrogel particles of step (b) to provide dry superabsorbent particles;
(d) applying a mixture comprising a surface crosslinking agent and a clay to the surface of the superabsorbent particles of step (c) to provide surface-treated superabsorbent polymer particles; and
(e) then heating the surface-treated superabsorbent polymer particles for a sufficient time at a sufficient temperature to surface crosslink the surface-treated superabsorbent polymer particles and position the clay in the vicinity of the surfaces of the surface-crosslinked superabsorbent particles. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27)
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28. A method of manufacturing surface-crosslinked superabsorbent polymer particles having a clay positioned in a vicinity of surfaces of the particles comprising the steps of:
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(a) forming an aqueous monomer mixture comprising (i) at least one monomer capable of forming a superabsorbent polymer, (ii) an internal crosslinking agent, and (iii) a polymerization catalyst;
(b) polymerizing the monomer in the aqueous mixture to form a superabsorbent polymer hydrogel;
(c) comminuting the superabsorbent polymer hydrogel to provide superabsorbent polymer hydrogel particles;
(d) drying the superabsorbent polymer hydrogel particles for a sufficient time at a sufficient temperature to provide dry superabsorbent polymer particles;
(e) applying a mixture of a clay and a surface crosslinking agent to surfaces of the dry superabsorbent polymer particles to provide surface-treated superabsorbent polymer particles; and
(f) heating the surface treated superabsorbent polymer particles for a sufficient time at a sufficient temperature to surface crosslink the surface treated superabsorbent polymer particles and position the clay in the vicinity of the surfaces of the particles. - View Dependent Claims (29, 30)
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Specification