Bleaching and shive reduction process for non-wood fibers

Patent metadata

Field	Value
Publication number	US-10711399-B2
Application number	US-201514716247-A
Country	US
Kind code	B2
Filing date	May 19, 2015
Priority date	May 20, 2014
Publication date	Jul 14, 2020
Grant date	Jul 14, 2020

Abstract

The present invention is directed to a method for scouring and increasing the brightness of non-wood fibers. The method comprises forming a mixture of non-wood fibers, exposing the mixture to a scouring liquor and a scouring agent comprising oxygen gas to form a scouring mixture, and scouring the scouring mixture by radially circulating the scouring liquor throughout the scouring mixture to provide scoured fibers.

First claim

What is claimed is:

1. A method for scouring and increasing the brightness of non-wood fibers, the method comprising:
forming a mixture of non-wood fibers having a mean length of at least 7 millimeters (mm) into a fiber mat within a perforated basket arranged within a kier;
exposing the mixture to a scouring liquor and a scouring agent comprising oxygen gas to form a scouring mixture; and
scouring the scouring mixture in the perforated basket by radially circulating the scouring liquor, by a circulation pump, throughout the mixture to provide scoured fibers.

2. The method of claim 1 , wherein scouring is performed at a temperature between about 95 and about 150° C.

3. The method of claim 1 , wherein scouring is performed at a temperature less than 110° C.

4. The method of claim 3 , wherein the scouring liquor comprises magnesium sulfate.

5. The method of claim 1 , further comprising dissolving the oxygen gas in the scouring liquor under a pressure in a range between about 1 and about 10 Bar.

6. The method of claim 1 , further comprising cooling the scoured fibers to a temperature below 100° C.

7. The method of claim 1 , further comprising draining the scouring liquor from scoured fibers.

8. The method of claim 7 , further comprising rinsing the scoured fibers with water and then centrifuging the scoured fibers to remove excess water.

9. The method of claim 1 , further comprising introducing a gas into the chamber after scouring to displace residual scouring liquor from the scoured fibers.

10. The method of claim 1 , further comprising drying the scoured fibers.

11. The method of claim 1 , further comprising internally recirculating the scouring liquor within the kier.

12. The method of claim 11 , further comprising externally recirculating the scouring liquor outside the kier.

13. The method of claim 1 , wherein the scouring liquor comprises magnesium sulfate.

14. The method of claim 1 , wherein the scouring liquor comprises sodium hydroxide.

15. The method of claim 1 , further comprising exposing the non-wood fibers to an organic acid.

16. The method of claim 15 , wherein the organic acid is acetic acid, citric acid, formic acid, lactic acid, oxalic acid, uric acid, or any salt thereof.

17. The method of claim 16 , where in the salt of citric acid is trisodium citrate, calcium citrate, or both trisodium citrate and calcium citrate.

18. The method of claim 1 , wherein the non-wood fibers are bast fibers.

19. The method of claim 1 , wherein the non-wood fibers are flax fibers, hemp fibers, jute fibers, ramie fibers, nettle fibers, Spanish broom fibers, kenaf plant fibers, or any combination thereof.

20. The method of claim 1 , wherein the non-wood fibers are cotton fibers.

21. The method of claim 1 , wherein the scouring liquor has a pH in a range between about 6 and about 8.

22. The method of claim 1 , wherein the scouring liquor has a pH in a range between about 7 and about 12.

23. The method of claim 1 , further comprising carding the scoured fibers.

24. The method of claim 1 , further comprising hydroentangling the scoured fibers.

25. A method for increasing the brightness of non-wood fibers, the method comprising:
forming a mixture of non-wood fibers having a mean length of at least 7 millimeters (mm) into a fiber mat within a perforated basket arranged within a kier; and
scouring the mixture in the perforated basket with a scouring liquor comprising oxygen gas to provide scoured and brightened fibers, the scouring comprising radially circulating and recirculating the scouring liquor through the mixture using a circulation pump;
wherein the scoured and brightened fibers have a brightness in a range between about 30 and about 60 as measured by Technical Association of the Pulp and Paper Industry (TAPPI) 525 standard test method.

26. The method of claim 25 , wherein scouring is performed at a temperature less than 110° C.

27. The method of claim 25 , wherein the scouring liquor comprises magnesium sulfate.

28. The method of claim 25 , further comprising draining the scouring liquor from scoured fibers.

29. The method of claim 28 , further comprising rinsing the scoured fibers with water and then centrifuging the scoured fibers to remove excess water.

30. The method of claim 29 , further comprising introducing a gas after scouring to displace residual scouring liquor from the scoured fibers.

31. The method of claim 25 , further comprising drying the scoured fibers.

32. The method of claim 25 , wherein the scouring liquor comprises magnesium sulfate.

33. The method of claim 25 , further comprising exposing the non-wood fibers to an organic acid.

34. The method of claim 33 , wherein the organic acid is acetic acid, citric acid, formic acid, lactic acid, oxalic acid, uric acid, or any salt thereof.

35. The method of claim 34 , where in the salt of citric acid is trisodium citrate, calcium citrate, or both trisodium citrate and calcium citrate.

36. The method of claim 25 , wherein the non-wood fibers are bast fibers.

37. The method of claim 25 , wherein the non-wood fibers are flax fibers, hemp fibers, jute fibers, ramie fibers, nettle fibers, Spanish broom fibers, kenaf plant fibers, or any combination thereof.

38. The method of claim 25 , wherein the non-wood fibers are cotton fibers.

39. The method of claim 25 , further comprising bleaching the scoured and brightened fibers to provide bleached fibers.

40. The method of claim 39 , wherein bleaching comprises exposing the scoured and brightened fibers to a peroxide compound, oxygen gas, a reducing agent, or a combination thereof.

41. The method of claim 39 , further comprising exposing the bleached fibers to a second bleaching stage.

42. The method of claim 41 , wherein the second bleaching stage comprises exposing the bleached fibers to a peroxide compound, oxygen gas, a reducing agent, or a combination thereof.

43. A method of reducing the amount of residual shive in non-wood fibers, the method comprising:
forming a mixture of non-wood fibers having a mean length of at least 7 millimeters (mm) into a fiber mat within a perforated basket within a kier; and
scouring the mixture in the perforated basket with a scouring liquor comprising oxygen gas to provide scoured and low-shive fibers, the scouring comprising radially circulating the scouring liquor through the mixture using a circulation pump;
wherein the scoured and low-shive fibers have less visible shive content than the fibers of the mixture before exposure.

44. The method of claim 43 , wherein the structural integrity of the residual shive is reduced during scouring.

45. The method of claim 43 , wherein scouring is performed at a temperature between about 95 and about 150° C.

46. The method of claim 43 , wherein scouring is performed at a temperature less than 110° C.

47. The method of claim 46 , wherein the scouring liquor comprises magnesium sulfate.

48. The method of claim 43 , further comprising dissolving the oxygen gas in the scouring li

Assignees

• Georgia Pacific Consumer Products Lp
• Gpcp Ip Holdings Llc

Inventors

• Lee Jeffrey A
• Harwood Raymond Jeffrey
• Smith Edward J

Classifications

• D21C9/147 Primary

  with oxygen or its allotropic modifications (D21C9/16 takes precedence) · CPC title

• Y02W30/64

  Paper recycling · CPC title

• Y10T442/60

  Nonwoven fabric [i.e., nonwoven strand or fiber material] · CPC title

• D21H11/14

  Secondary fibres (working-up waste paper D21C5/02) · CPC title

• D21H11/12

  Pulp from non-woody plants or crops, e.g. cotton, flax, straw, bagasse · CPC title