Nonwoven glucan webs
Nonwoven webs comprising a water insoluble α-(1,3→glucan) polymer and methods of forming the nonwoven webs are disclosed. The water insoluble α-(1,3→glucan) polymer comprises 90% or greater α-1,3-glycosidic linkages, less than 1% by weight of α-1,3,6-glycosidic branch points, a number average degree of polymerization in the range of from 55 to 10,000, and a ratio of apparent DPw to true DPw in the range of from 2 to 10. The nonwoven webs can be used for personal hygiene wipes, filtration media, apparel, or other uses.
1. A process comprising:
(a) introducing an aqueous solution of a water insoluble α-(1,3→glucan) polymer to a chamber;
(b) contacting a pressurized gas with the aqueous solution of step (a) in the chamber to form fibers; and
(c) collecting the fibers to form a nonwoven web;
wherein the aqueous solution comprises the water insoluble α-(1,3→glucan) polymer in an aqueous base, and wherein the water insoluble α-(1,3→glucan) polymer has 90% or greater α-1,3-glycosidic linkages.
2. The process of claim 1 , further comprising a step of fragmenting the aqueous solution with the pressurized gas prior to step (c).
3. The process of claim 1 , further comprising a step of:
(d) removing at least a portion of water and/or the aqueous base from the nonwoven web.
4. The process of claim 1 , wherein the nonwoven web is washed with water or acid.
5. The process of claim 1 , wherein the water insoluble α-(1,3→glucan) polymer has greater than or equal to 99% α-1,3-glycosidic linkages.
6. The process of claim 1 , wherein the nonwoven web consists essentially of the water insoluble α-(1,3→glucan) polymer.
7. The process of claim 1 , wherein the water insoluble α-(1,3→glucan) polymer has a number average degree of polymerization in the range of 75 to 1000.
8. The process of claim 1 , wherein the pressurized gas is air.
9. The process of claim 1 , wherein the aqueous solution comprises 5 to 30% by weight of the water insoluble α-(1,3→glucan) polymer, wherein the percentage by weight is based on the total amount of the aqueous solution.
10. The process of claim 1 , wherein the aqueous base comprises aqueous sodium hydroxide or aqueous potassium hydroxide.
11. The process of claim 1 , wherein the chamber has an electrical charge.
12. The process of claim 1 , wherein step (b) comprises increasing the pressure of the pressurized gas thereby forming shorter fibers prior to step (c).
13. The process of claim 1 , wherein the water insoluble α-(1,3→glucan) polymer has less than 1 % α-1,3,6-glycosidic branch points.
14. The process of claim 1 , wherein the water insoluble α-(1,3→glucan) polymer has a number average degree of polymerization of 55 to 10000.
15. The process of claim 1 , wherein the aqueous solution in step (a) is introduced to the chamber from a vessel, wherein the aqueous solution flows through at least one orifice of the vessel into the chamber.
16. The process of claim 15 , wherein the aqueous solution is forced through said at least one orifice of the vessel by pressure.
17. The process of claim 15 , wherein the aqueous solution flows through said at least one orifice of the vessel by gravity.
18. The process of claim 1 , wherein the aqueous solution in step (a) is introduced to the chamber from a nozzle or spinneret.
19. The process of claim 18 , wherein the aqueous solution is forced through the nozzle or spinneret by pressure.
20. The process of claim 18 , wherein the aqueous solution flows through the nozzle or spinneret by gravity.
21. The process of claim 1 , wherein the pressurized gas is introduced to the chamber at a velocity of 10 to 340 meters/second.
22. The process of claim 1 , wherein the pressurized gas is introduced to the chamber at a velocity of 30 to 250 meters/second.
23. The process of claim 1 , wherein the pressurized gas is introduced to the chamber at a velocity of 50 to 160 meters/second.
24. The process of claim 1 , wherein the fibers are collected onto a metal plate, metal roll, polymeric plate, polymeric roll, or polymeric belt.
25. The process of claim 1 , wherein the fibers are collected onto a perforated substrate.
26. The process of claim 1 , wherein the fibers are collected onto a metal screen or polymeric screen.
27. The process of claim 1 , wherein the fibers are collected onto a solid substrate that is stationary or moving.