Inflated fibers of regenerated cellulose formed from ionic liquid/cellulose dope and related products
Inflated fibers of regenerated cellulose and other regenerated structures are formed from ionic liquid/cellulose dope. Fibers so produced may be incorporated into absorbent sheet with other papermaking fibers to provide softness, bulk and absorbency.
1. A method of making an inflated article of regenerated cellulose comprising:
(a) preparing a cellulosic dope comprising cellulose dissolved in a suitable ionic liquid or quasi-ionic liquid;
(b) dispersing an effervescing agent in the cellulosic dope, the effervescing agent and ionic liquid or quasi-ionic liquid being selected such that they are substantially inert with respect to each other;
(c) regenerating the cellulosic dope into a shaped article comprising a regenerated cellulose matrix having dispersed therein substantially unreacted effervescing agent encapsulated by the regenerated cellulose matrix; and
(d) thereafter, activating the encapsulated effervescing agent to generate a gas in-situ within the regenerated cellulose matrix and create a shaped article with an inflated structure.
2. The method according to claim 1 , wherein the shaped article with an inflated structure is a fiber with an inflated structure.
3. The method according to claim 1 , wherein the shaped article with an inflated structure is a film with an inflated structure.
4. The method according to claim 1 , wherein the cellulose dope comprises an ionic liquid which is an imidazolium salt.
5. The method according to claim 4 , wherein the imidazolium salt is selected from: 1-allyl-3-methylimidazolium chloride; 1-butyl-3-methylimidazolium chloride; and 1-ethyl-3-methylimidazolium acetate.
6. The method according to claim 1 , wherein the effervescing agent comprises a powdered carbonate salt.
7. The method according to claim 6 , wherein the carbonate salt is calcium carbonate, sodium carbonate or sodium bicarbonate.
8. The method according to claim 1 , wherein the effervescing agent is activated by contacting the shaped article with an acid.
9. The method according to claim 8 , wherein the acid is a mineral acid.
10. The method according to claim 8 , wherein the acid is an organic acid.
11. The method according to claim 10 , wherein the organic acid is selected from citric acid, acetic acid, trichloroacetic acid, oxalic acid, malonic acid, maleic acid, lactic acid, glycolic acid, formic acid, benzoic acid, fumaric acid, malic acid and tartaric acid.
12. The method according to claim 1 , wherein the effervescing agent is selected and the step of activating the encapsulated effervescing agent is carried out to completion, such that the shaped article with an inflated structure is substantially bereft of encapsulated effervescing agent.
13. The method according to claim 1 , wherein the cellulosic dope is regenerated with water.
14. The method according to claim 1 , wherein the cellulosic dope is regenerated with an aqueous surfactant composition selected to control the size of the regenerated article.
15. A method of making a wet-laid absorbent sheet comprising:
(a) preparing inflated regenerated fibers by way of (i) preparing a cellulosic dope comprising cellulose dissolved in a suitable ionic liquid or quasi-ionic liquid, (ii) dispersing an effervescing agent in the cellulosic dope, the effervescing agent and ionic liquid or quasi-ionic liquid being selected such that they are substantially inert with respect to each other, (iii) regenerating the cellulosic dope into a fiber comprising a regenerated cellulose matrix having disposed therein substantially unreacted effervescing agent encapsulated by the regenerated cellulose matrix, and (iv) thereafter, activating the encapsulated effervescing agent to generate a gas in-situ within the regenerated cellulose matrix and create a fiber with an inflated structure;
(b) preparing an aqueous furnish incorporating the inflated regenerated cellulose fibers made by step (a) as well as pulp-derived papermaking fibers;
(c) depositing the aqueous furnish on a foraminous support to form a nascent web and at least partially dewatering the nascent web; and
(d) drying the web to provide absorbent sheet.
16. The method according to claim 15 , wherein the aqueous furnish comprises a pulp derived fiber selected from Kraft hardwood fiber, Kraft softwood fiber, recycle fiber and mixtures thereof.