Swellable hydrogel-forming polymers having a low fraction of fines
Swellable hydrogel-forming polymer comprising at least one hydrophilic polymer of dendritic structure, a process for preparing the swellable hydrogel-forming polymer and also its use in hygiene articles.
1. Swellable hydrogel-forming polymer particles comprising (a) a swellable hydrogel-forming polymer and (b) up to 10% by weight, based on the swellable hydrogel-forming polymer particles, of at least one hydrophilic polymer having a dendritic structure, wherein the swellable hydrogel-forming polymer particles have a particle size in the range of 45 to 1000 μm.
2. The polymer particles of claim 1 wherein said swellable hydrogel-forming polymer particles comprise at least 0.005%, by weight, of the hydrophilic polymer having a dendritic structure.
3. The polymer particles of claim 1 wherein the hydrophilic polymer having a dendritic structure comprises a polyester formed from a polyol and 2,2-dimethylolpropionic acid.
4. The polymer particles of claim 1 wherein the hydrophilic polymer having a dendritic structure comprises a polypropyleneimine, a polyamidoamine, or a polyesteramide.
5. The polymer particles of claim 1 further comprising a powdery additive, a dusty additive, or a mixture thereof.
6. The polymer particles of claim 5 wherein said additive is a metal salt, a pyrogenic silica, a polysaccharide, a nonionic surfactant, a wax, diatomaceous earth, or a mixture thereof.
7. The polymer particles of claim 5 wherein said additive is in a form of hollow microspheres from 1 to 1000 μm in diameter and having a wall thickness of 1% to 10% of said diameter.
8. The polymer particles of claim 1 comprising less than 50 weight ppm of particles less than 10 μm in diameter.
9. The polymer particles of claim 1 comprising less than 50 weight ppm of particles less than 10 μm in diameter after exposure to mechanical stress.
10. The polymer particles of claim 1 wherein the hydrophilic polymer having a dendritic structure is present on the surfaces of the swellable hydrogel-forming polymer particles.
11. The polymer particles of claim 1 wherein the swellable hydrogel-forming polymer particles comprise crosslinked, partially neutralized polyacrylic acid.
12. A process for preparing swellable hydrogel-forming polymer particles of claim 1 comprising mixing dried, water-absorbing hydrogel particles with at least one hydrophilic polymer having a dendritic structure.
13. The process of claim 12 wherein said hydrophilic polymer of dendritic structure comprises a polyester formed from a polyol and 2,2-dimethylolpropionic acid.
14. The process of claim 12 wherein said hydrophilic polymer of dendritic structure comprises a polypropyleneimine, a polyamidoamine, or a polyesteramide.
15. The process of claim 12 further comprising a surface-postcrosslinking operation.
16. The process of claim 15 wherein the surface-postcrosslinking operation is performed using at least one surface postcrosslinker and a solvent comprising a mixture of isopropanol and water.
17. A method of absorbing blood or body fluids comprising contacting the blood or body fluids with the swellable hydrogel-forming polymer particles of claim 1 .
18. The method of claim 17 wherein the body fluid is urine.
19. A hygiene article comprising the swellable hydrogel-forming polymer particles of claim 1 , said articles selected from the group consisting of diapers, incontinence articles, sanitary napkins, tampons, and liners.