Method of pulping cotton-based raw material

Patent metadata

Field	Value
Publication number	US-11939405-B2
Application number	US-201716472482-A
Country	US
Kind code	B2
Filing date	Dec 22, 2017
Priority date	Dec 22, 2016
Publication date	Mar 26, 2024
Grant date	Mar 26, 2024

Abstract

The present invention relates to a method of pulping cotton-based raw material for producing dissolving pulp. More specifically, the invention relates to a process for producing dissolving pulp under alkaline conditions in combination with a gaseous oxidizing agent. The present invention further relates to dissolving pulp obtainable by pulping cotton-based raw material, in particular dissolving pulp obtainable by the method of the present invention, the use of such dissolving pulp for producing regenerated cellulose molded bodies, and methods of producing lyocell or viscose including such dissolving pulp.

First claim

What is claimed is:

1. A method of pulping a cotton-based raw material for producing dissolving pulp, said method comprising:
a. an incubation step for generating the dissolving pulp by incubating the cotton-based raw material with an alkaline solution in combination with a gaseous oxidizing agent in a pressurized vessel
i. at a temperature of about 90-about 185° C.,
ii. for an incubation time of about 45-about 270 min,
iii. in the presence of a cellulose-stabilizing additive,
iv. at a concentration of alkali of about 1-about 35% (w/w) of the cotton-based raw material, and
v. at an initial gas pressure of about 1-about 21 bar (about 0.1 MPa-about 2.1 MPa), thereby generating the dissolving pulp; and

b. a step of washing the dissolving pulp,
wherein the cotton-based raw material is a pre- or post-consumer material,
wherein step a. is the only step for generating the dissolving pulp.

2. The method of claim 1 , wherein the alkaline solution is a solution of potassium hydroxide, sodium hydroxide, sodium carbonate or a combination thereof.

3. The method of claim 2 , wherein the alkaline solution is a solution of sodium hydroxide.

4. The method of claim 1 , wherein the gaseous oxidizing agent is or comprises oxygen (O 2 ).

5. The method of claim 1 , wherein the cellulose-stabilizing additive is a magnesium salt.

6. The method of claim 5 , wherein the cellulose-stabilizing additive is magnesium sulfate.

7. The method of claim 1 , wherein the cellulose-stabilizing additive is a transition metal chelator.

8. The method of claim 7 , wherein the cellulose-stabilizing additive is EDTA, DTPA, NTA, DTPMPA or any combination thereof.

9. The method of claim 1 , wherein the concentration of the cellulose-stabilizing additive is about 0.01-about 5.00% (w/w) of the cotton-based raw material.

10. The method of claim 1 , wherein step (a) is preceded by a step of mechanically disintegrating the cotton-based raw material.

11. The method of claim 1 , wherein the temperature is about 100-about 150° C., the incubation time is about 90-about 150 min, the concentration of alkali is about 4-about 20% (w/w) of the cotton-based raw material, the initial gas pressure is about 2-about 10 bar (about 0.2 MPa-about 1.0 MPa), the concentration of the cellulose-stabilizing additive is about 0.05-about 2.00% (w/w) of the cotton-based raw material, or any combination thereof.

12. The method of claim 1 , wherein the concentration of alkali is sufficient to obtain a pH of at least about pH 9.

13. The method of claim 1 , wherein the dissolving pulp comprises a level of carbonyl groups, carboxyl groups or carbonyl and carboxyl groups.

14. The method of claim 13 , wherein the level of carbonyl groups is below about 0.40 μmol/g and/or the level of carboxyl groups is below about 4.00 μmol/g.

Assignees

• Chemiefaser Lenzing Ag

Inventors

• Silbermann Stephan
• Weilach Christian

Classifications

• C08B16/00 Primary

  Regeneration of cellulose · CPC title

• C08B9/00

  Cellulose xanthate; Viscose {(formation of films C08J5/18; formation of fibres D01F; rendering cellulose suitable for esterification C08B1/02)} · CPC title

• C08K3/30

  Sulfur-, selenium- or tellurium-containing compounds · CPC title

• C08K5/175

  containing COOH-groups; Esters or salts thereof · CPC title

• D01F2/00

  Monocomponent artificial filaments or the like of cellulose or cellulose derivatives; Manufacture thereof · CPC title