Dissolution of Cellulose in Mixed Solvent Systems

• US 20090088564A1
• Filed: 09/29/2008
• Published: 04/02/2009
• Est. Priority Date: 09/28/2007
• Status: Active Grant

• Current Assignee: International Paper Company
• Original Assignee: Weyerhaeuser Company (Weyerhauser)
• Inventors: Neogi, Amar N., Luo, Mengkui, West, Hugh
• Granted Patent: US 7,828,936 B2
• Time in Patent Office: Days
• US Class Current: 536/57
• CPC Class Codes: C08B 1/003 Preparation of cellulose solutions, i.e. dopes, with different possible solvents, e.g. ionic liquids solutions used in the manufacture of monocomponent artificial filaments or cellulose or derivatives thereof D01F2/02
• CPC Class Codes: D01F 2/02 from solutions of cellulose in acids, bases or salts

Abstract

A method for dissolving cellulose in which the cellulose based raw material is admixed with a mixture of a dipolar aprotic intercrystalline swelling agent and an ionic liquid at a temperature of 25° C. to 180° C. for a time sufficient to dissolve the cellulose based raw material. The molar ratio of dipolar aprotic intercrystalline swelling agent to ionic liquid is 0.05 to 1.5 moles of dipolar aprotic intercrystalline swelling agent to 1 mole of ionic liquid. Dipolar aprotic intercrystalline swelling agents do not include imidazole based agents or amine based agents.

Claims

1. A method for dissolving cellulose comprising

admixing a cellulose based raw material with a mixture of an dipolar aprotic intercrystalline swelling agent and an ionic liquid at a temperature of 25°

C. to 1 80°

C. for a time sufficient to dissolve the cellulose based raw material, wherein the molar ratio of dipolar aprotic intercrystalline swelling agent to ionic liquid is 0.5 to 25 moles of dipolar aprotic intercrystalline swelling agent to 1 mole of ionic liquid, and wherein the dipolar aprotic intercrystalline swelling agents is not an imidazole based agent or amine based agent.

2. The method of claim 1 wherein the cellulose based raw material is wood chips, wood pulp, kenaf or straw.

4. The method of claim 1 wherein the temperature range is 80°

C. to 120°

C.

5. The method of claim 1 wherein the temperature range is 100°

C. to 1 10°

C.

6. The method of claim 1 wherein the molar ratio is 0.5 to 15 moles of dipolar aprotic intercrystalline swelling agent to 1 mole of ionic liquid.

7. The method of claim 1 wherein the molar ratio is 0.5 to 2 moles of dipolar aprotic intercrystalline swelling agent to 1 mole of ionic liquid.

8. The method of claim 1 wherein the time is 5 minutes to 24 hours.

9. The method of claim 1 wherein the time is 5 minutes to 1 hour.

10. The method of claim 1 wherein the dipolar aprotic intercrystalline swelling agent is dimethyl sulfoxide (DMSO), dimethyl acetamide (DMAc), N-methylmorpholine N-oxide, formamide, pyridine, acetone, dioxane, N-methyl pyrolidine (NMP), piperylene sulfone or hexamethylphosphoramide (HMPA), or mixtures thereof.

11. The method of claim 1 wherein the ionic liquid is 1-ethyl-3-methyl imidazolium chloride, 1-ethyl-3-methyl imidazolium acetate, 1-butyl-3-methyl imidazolium chloride, 1-allyl-3-methyl imidazolium chloride, zinc chloride/choline chloride, 3-methyl-N-butyl-pyridinium chloride, benzyldimethyl(tetradecyl) ammonium chloride or 1-methylimidazolehydrochloride, or mixtures thereof.

12. The method of claim 1 further comprising regenerating the dissolved cellulose.

3. The method of claim 3 wherein the wood pulp is chemical wood pulp, kraft wood pulp, sulfite wood pulp, mechanical wood pulp, thermomechanical wood pulp, or chemithermomechanical wood pulp.