Cellulose ethylsulfonate-based 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 process for the preparation of water-insoluble cellulose alkyl sulfonate comprising simultaneously reacting 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 there is no organic solvent present in the reaction.
2. The process of claim 1 , wherein the weight of water present in the reaction is less than 800% by weight of the cellulose.
3. The process of claim 1 , wherein the weight of water present in the reaction is less than 700% by weight of the cellulose.
4. The process of claim 1 , wherein the weight of the water present in the reaction is less than 650% by weight of the cellulose.
5. The process of claim 1 , wherein the alkenyl sulfonate is an α-alkenyl sulfonate.
6. The process of claim 5 , wherein the α-alkenyl sulfonate is a lower alkenyl sulfonate.
7. The process of claim 1 , wherein the alkenyl sulfonate is selected from the group consisting of vinyl sulfonate, allyl sulfonate, isopropenyl sulfonate, 1-butenyl sulfonate, 1-methyl allyl sulfonate, and 2-methylallyl sulfonate.
8. The process of claim 1 wherein the alkenyl sulfonate is vinyl sulfonate.
9. A process for the preparation of a water-insoluble cellulose alkyl sulfonate comprising the steps of:
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 in a medium that contains no organic solvent; and
c. isolating the product of step (b).
10. The process of claim 9 , wherein an amount of water present in step (b) is more than 650% by weight of the cellulose.
11. The process of claim 9 , wherein the weight of the water present in step (b) is less than 750% by weight of the cellulose.
12. The process of claim 9 , wherein the alkenyl sulfonate is an α-alkenyl sulfonate.
13. The process of claim 9 , wherein the α-alkenyl sulfonate is a lower alkenyl sulfonate.
14. The process of claim 9 , wherein the alkenyl sulfonate is selected from the group consisting of vinyl sulfonate, allyl sulfonate, isopropenyl sulfonate, 1-butenyl sulfonate, 1-methyl allyl sulfonate, and 2-methylallyl sulfonate.
15. The process of claim 9 , wherein the alkenyl sulfonate is vinyl sulfonate.
16. The process of claim 9 further comprising the step of (d) drying the product of step (c).
17. The process of claim 9 wherein said alkali is sodium hydroxide.