Surface cross-linked superabsorbent polymer particles and methods of making them
AssigneeThe Procter & Gamble Company
InventorsAndreas Flohr, Torsten Lindner
Life of this patent
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Abstract
Superabsorbent polymer particles with improved surface cross-linking and their use in absorbent articles. The superabsorbent polymer particles comprise polymer chain segments, wherein at least a part of the polymer chain segments are covalently cross-linked to each other and wherein at least a part of the cross-links include the reaction product of cross-linking molecules having at least two C═C double bonds and further include the reaction product of radical former molecules. These cross-links are present at surfaces of the superabsorbent polymer particles.
Claims11
A superabsorbent polymer, comprising:
- a. superabsorbent polymer particles selected from the group consisting of granules, flakes, spheres, powders, platelets, and beads, each of the particles comprising a surface and a core, wherein a plurality of aliphatic C—H groups are present at the surface;
- and
- b. polymer chain segments, wherein at least some of said polymer chain segments are covalently surface cross-linked to each other after formation of said superabsorbent polymer particles to provide surface cross-links, wherein at least some of the surface cross-links comprise the reaction product of cross-linking molecules having at least two C═C double bonds and wherein at least some of the surface cross-links further comprise the reaction product of radical former molecules that chemically react with the aliphatic C—H groups when the radical former molecules are irradiated.
A method of surface cross-linking superabsorbent polymer particles comprising:
- providing discrete superabsorbent polymer particles selected from the group consisting of granules, flakes, spheres, powders, platelets, and beads, each of the particles comprising a surface and a core, wherein a plurality of aliphatic C—H groups are present at the surface, the particles comprising polymer chain segments;
- adding a surface cross-linking composition comprising cross-linking molecules having at least two C═C double bonds and further comprising radical former molecules wherein the radical former molecules, when irradiated, chemically react with the aliphatic C—H groups;
- and
- exposing said superabsorbent polymer particles and said surface cross-linking composition to electromagnetic irradiation capable of activating said radical former,
- whereby said cross-linking molecules and said radical former molecules react with at least some of said polymer chain segments comprised at surfaces of the superabsorbent polymer particles to form covalent cross-links between said polymer chain segments, wherein at least some of said cross-links comprise the reaction product of said cross-linking molecule and wherein at least some of said cross-links further comprise the reaction product of said radical former molecules.
Dependencies are inferred from the claim text.