Recycling of man-made cellulosic fibers

Patent metadata

Field	Value
Publication number	US-10370778-B2
Application number	US-201615545899-A
Country	US
Kind code	B2
Filing date	Feb 3, 2016
Priority date	Feb 6, 2015
Publication date	Aug 6, 2019
Grant date	Aug 6, 2019

Abstract

A process for producing a man-made cellulosic molded body using a man-made cellulosic raw material, including the steps of forming a cellulose solution by dissolution of cellulosic raw material, the extrusion of the cellulose solution obtained to form a molded body, and coagulation and regeneration of the cellulose to obtain the man-made cellulosic molded body, wherein the man-made cellulosic raw material is mixed with a second cellulosic raw material prior to forming the cellulose solution.

First claim

The invention claimed is:

1. A process for producing a man-made cellulosic molded body using a reclaimed man-made cellulosic raw material and a virgin cellulosic raw material, comprising the steps of:
a) steeping the reclaimed man-made cellulosic raw material in caustic soda in an alkalization stage and subsequently squeezing to obtain alkali cellulose,
b) xanthation of the alkali cellulose and subsequently dissolution of cellulose xanthate to obtain a cellulose xanthate solution,
c) extruding the cellulose xanthate solution,
d) coagulating and regenerating cellulose to obtain the man-made cellulosic molded body,
wherein before step b) in an additional combination step the alkali cellulose made of the reclaimed man-made cellulosic raw material is combined with alkali cellulose made of the virgin cellulosic raw material in a second alkalization line and wherein the combined alkali celluloses are further processed jointly in the xanthation step b).

2. The process according to claim 1 , wherein the reclaimed man-made cellulosic raw material was obtained from pre- and/or post-consumer waste containing man-made cellulosic fibers produced by the viscose-, modal or lyocell process.

3. The process according to claim 2 , wherein the pre- and/or post-consumer waste further comprises non-cellulosic fibers and wherein these non-cellulosic fibers are quantitatively separated from the reclaimed man-made cellulosic raw material prior to step a).

4. The process according to claim 1 , further comprising a metal removing stage which comprises an acidic washing treatment and/or a treatment with a complexing agent.

5. The process according to claim 4 , wherein the acidic washing treatment and the treatment with a complexing agent in the metal removing stage are combined in one step by adding a complexing agent to the acidic washing treatment.

6. The process according to claim 1 , wherein the molded body is a staple fiber, filament fiber, sponge or foil of the Viscose or Modal type.

7. The process according to claim 1 , wherein the difference between limiting viscosity numbers of the alkali cellulose of the reclaimed man-made cellulosic raw material and the alkali cellulose of virgin cellulosic raw material is equal to or lower than 30 ml/g.

8. The process according to claim 1 , wherein the reclaimed man-made cellulosic raw material is a staple fiber, filament fiber, sponge or foil of the Viscose or Modal type or of the Lyocell type.

9. The process according to claim 1 , wherein in the additional combination step a share of the reclaimed man-made cellulosic raw material is from 10 to 90%.

10. The process according to claim 7 , wherein the difference between the limiting viscosity numbers of the alkali cellulose of the reclaimed man-made cellulosic raw material and the alkali cellulose of virgin cellulosic raw material is equal to or lower than 10 ml/g.

11. The process according to claim 9 , wherein the share of the reclaimed man-made cellulosic raw material is from 20 to 80%.

12. The process according to claim 11 , wherein the share of the reclaimed man-made cellulosic raw material is from 40 to 60%.

13. The process according to claim 1 , further comprising mechanically shredding the reclaimed man-made cellulosic raw material.

14. The process according to claim 1 , further comprising pre-treating the reclaimed man-made cellulosic raw material in a metal removing stage, a decoloring stage and/or cross linker removing stage prior to the alkalization step.

15. The process according to claim 1 , further comprising pre-aging the alkali cellulose.

Assignees

• Chemiefaser Lenzing Ag

Inventors

• Sperger Christian

Classifications

• C08J11/04

  of polymers · CPC title

• D01F13/02 Primary

  of cellulose, cellulose derivatives or proteins {(recovery of sodium sulfate from coagulation baths C01D5/006)} · CPC title

• C08B9/06

  Single-stage processes · CPC title

• D01F2/08

  Composition of the spinning solution or the bath · CPC title

• C08B16/00

  Regeneration of cellulose · CPC title