Superabsorbent polymer compositions having color stability
AssigneeEvonik Stockhausen GmbH
InventorsIqbal Ahmed, Mirko Walden, Brian King, Scott J. Smith, Harald Schmidt
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Abstract
The invention relates to absorptive, crosslinked polymeric compositions that are based on partly neutralized, monoethylenically unsaturated monomer carrying acid groups wherein the absorptive, crosslinked polymeric composition further includes an antioxidant and is color stable.
Claims40
A superabsorbent polymer composition comprising a superabsorbent polymer comprising:
- a) from about 55% to about 99.9% by weight of the superabsorbent polymer of polymerizable unsaturated acid group containing monomer based on the superabsorbent polymer;
- and
- b) from about 0.001% to about 5% by weight of internal crosslinking agent based on the polymerizable unsaturated acid group containing monomer;
- c) from about 50 to 1000 ppm of a thermal initiator based on the polymerizable unsaturated acid group containing monomer;
- wherein the superabsorbent polymer has a degree of neutralization of greater than about 25%;
- wherein elements a), b) and c) are polymerized into a crosslinked hydrogel, which is then prepared into superabsorbent polymer particles;
- the superabsorbent polymer composition further comprising the following additives to form superabsorbent polymer composition particles
- i) from about 0.001% to about 5% by weight of surface crosslinking agent based on the superabsorbent polymer composition;
- and
- wherein from about 0.01% to about 5% by weight of an antioxidant based on the superabsorbent polymer composition is added to the polymerized product whether in crosslinked hydrogel or subsequent superabsorbent polymer particles or superabsorbent polymer composition particle form wherein the superabsorbent polymer composition has a free swell gel bed permeability of at least about 6 Darcy as measured by the Free Swell Gel Bed Permeability Test.
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The superabsorbent polymer composition comprising a superabsorbent polymer comprising superabsorbent polymer particles surface treated with i) from about 0.01% to about 5% by weight of a polymeric coating based on the superabsorbent polymer composition;
- and ii) from about 0.01% to about 5% by weight of an antioxidant based on the superabsorbent polymer composition wherein the antioxidant is added to the polymerized product whether in crosslinked hydrogel or subsequent superabsorbent polymer particles or superabsorbent polymer composition particle form.
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A method to make a superabsorbent polymer composition comprising the steps of:
- a) preparing a superabsorbent polymer by the process of polymerizing from about 55% to about 99.9% by weight of polymerizable unsaturated acid group containing monomer based on the superabsorbent polymer, and from about 0.001% to about 5% by weight of an internal crosslinking agent based on the polymerizable unsaturated acid group containing monomer, and from about 50 to 1000 ppm of a thermal initiator based on the polymerizable unsaturated acid group containing monomer, wherein the superabsorbent polymer has a degree of neutralization of greater than about 25%;
- b) polymerizing the components of a) into a hydrogel;
- c) preparing superabsorbent polymer particles from the superabsorbent polymer;
- d) treating the superabsorbent polymer particles with surface additives including:
- i) from about 0.001% to about 5% by weight of surface crosslinking agent based on the superabsorbent polymer composition;
- wherein from about 0.01% to about 5% by weight of an antioxidant based on the superabsorbent polymer composition is added to the polymerized product whether in crosslinked hydrogel or subsequent superabsorbent polymer particles or superabsorbent polymer composition particle form wherein the superabsorbent polymer composition has a free swell gel bed permeability of at least about 6 Darcy as measured by the Free Swell Gel Bed Permeability Test.
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A superabsorbent polymer composition comprising a superabsorbent polymer comprising:
- a) from about 55% to about 99.9% by weight of the superabsorbent polymer of polymerizable unsaturated acid group containing monomer based on the superabsorbent polymer;
- and
- b) from about 0.001% to about 5% by weight of internal crosslinking agent based on the polymerizable unsaturated acid group containing monomer;
- c) from about 50 to 1000 ppm of a thermal initiator based on the polymerizable unsaturated acid group containing monomer;
- wherein the superabsorbent polymer has a degree of neutralization of greater than about 25%;
- wherein elements a), b) and c) are polymerized into a crosslinked hydrogel, which is then prepared into superabsorbent polymer particles;
- the superabsorbent polymer composition further comprising the following additives to form superabsorbent polymer composition particles
- i) from about 0.001% to about 5% by weight of surface crosslinking agent based on the superabsorbent polymer composition;
- and
- wherein from about 0.01% to about 5% by weight of an antioxidant selected from sulfinic acid, 2-hydroxy-2-sulfinatoacetic acid, 2-hydroxy-2-sulfonatoacetic acid or sulfonic acid, and salts or derivatives of the foregoing, based on the superabsorbent polymer composition is added to the polymerized product whether in crosslinked hydrogel or subsequent superabsorbent polymer particles or superabsorbent polymer composition particle form.
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Dependencies are inferred from the claim text.