Absorbent material
This invention relates to absorbent materials useful in the manufacture of absorbent articles, in particular dressings for the advanced wound care market. The absorbent materials of the present invention are sulfonated polysaccharides, particularly water-insoluble cellulose alkyl sulfonates in which the cellulose is substituted by one type of alkyl sulfonate group. The invention also provides a process for the manufacture of such materials. The preferred cellulose alkyl sulfonate described herein is cellulose ethyl sulfonate. Reinforcing fibers and/or antimicrobial agents are optionally applied to the cellulose alkyl sulfonate.
1. A water-insoluble polysaccharide alkyl sulfonate consisting of a polysaccharide substituted with one type of alkyl sulfonate, which has a fiber free absorbency in 0.9% saline solution as a test liquid of at least 2 g/g.
2. The water-insoluble polysaccharide alkyl sulfonate of claim 1 , wherein the polysaccharide alkyl sulfonate is a cellulose and wherein the cellulose is substituted with one type of alkyl sulfonate to form a cellulose alkyl sulfonate.
3. The cellulose alkyl sulfonate of claim 2 , which has a fiber free absorbency in 0.9% saline solution as a test liquid of at least 8 g/g.
4. The cellulose alkyl sulfonate of claim 2 , which has a fiber free absorbency in 0.9% saline solution as a test liquid of at least 9 g/g.
5. The cellulose alkyl sulfonate of claim 2 , which has a fiber free absorbency in 0.9% saline solution as a test liquid of at least 10 g/g.
6. The cellulose alkyl sulfonate of claim 2 , wherein the mean degree of substitution is less than 0.4 alkyl sulfonate groups per anhydroglucose unit.
7. The cellulose alkyl sulfonate of claim 2 , wherein the mean degree of substitution is less than 0.3 alkyl sulfonate groups per anhydroglucose unit.
8. The cellulose alkyl sulfonate of claim 2 , wherein the mean degree of substitution is 0.05 to 0.4 alkyl sulfonate groups per anhydroglucose unit.
9. The cellulose alkyl sulfonate of claim 2 , wherein said alkyl sulfonate has an alkyl moiety which is a lower alkyl.
10. The cellulose alkyl sulfonate of claim 9 , wherein the alkyl sulfonate moiety is selected from the group consisting of ethyl sulfonate, 1-methyl-ethyl sulfonate or 2-methyl-ethyl sulfonate.
11. The cellulose alkyl sulfonate of claim 9 , wherein the alkyl sulfonate moiety is ethyl sulfonate.
12. The cellulose alkyl sulfonate of claim 9 , wherein the alkyl sulfonate moiety is methyl sulfonate.
13. An absorbent fabric article comprising the absorbent water-insoluble polysaccharide alkyl sulfonate as set forth in claim 1 .
14. The absorbent fabric article of claim 13 , wherein said polysaccharide of said absorbent water-insoluble polysaccharide alkyl sulfonate is cellulose.
15. The absorbent fabric article of claim 13 , wherein said alkyl sulfonate of said absorbent water-insoluble polysaccharide alkyl sulfonate is ethyl sulfonate.
16. The absorbent fabric article of claim 13 , further comprising a reinforcing fiber blended or bonded with said water-insoluble polysaccharide alkyl sulfonate.
17. The absorbent fabric article of claim 16 , wherein said reinforcing fiber comprises a thermoplastic biocomponent fiber that is thermally bonded to said polysaccharide alkyl sulfonate.
18. The absorbent fabric article of claim 17 , wherein said thermoplastic biocomponent fiber comprises a sheath-core type comprising at least two polyolefins.
19. The absorbent fabric article of claim 18 , wherein said thermoplastic biocomponent fiber comprises 10 to 30 wt % and has a linear density of 1.7 to 16.7 decitex.
20. The absorbent fabric article of claim 16 , wherein said reinforcing fiber comprises a lyocell fiber.
21. The absorbent fabric article of claim 20 , wherein said lyocell fiber comprises 10 to 30 wt % and has a linear density of 0.7 to 30 decitex.
22. The absorbent fabric article as in one of claims 13 to 21 further comprising an antimicrobial agent.
23. The absorbent fabric article as in one of claims 13 to 21 further comprising an antimicrobial agent which is polyhexamethylene biguanide.
24. A water-insoluble cellulose alkyl sulfonate prepared by a process comprising simultaneously reacting a solvent spun cellulose with an alkali and an alkenyl sulfonate or its salt, and wherein an amount of water present in the reaction is less than 1030% by weight of the cellulose,
and wherein said water-insoluble cellulose alkyl sulfonate consists of cellulose substituted with one type of alkyl sulfonate.
25. A water-insoluble cellulose alkyl sulfonate prepared by a process comprising
(a) treating solvent spun cellulose with alkali;
(b) reacting the product of step (a) with an alkenyl sulfonate or its salts or chloromethane sulfonic acid or one of its salts; and
(c) isolating the product of step (b)
and wherein said water-insoluble cellulose alkyl sulfonate consists of cellulose substituted with one type of alkyl sulfonate.