Bleaching and shive reduction process for non-wood fibers

• US 10,640,899 B2
• Filed: 05/19/2015
• Issued: 05/05/2020
• Est. Priority Date: 05/20/2014
• Status: Active Grant

• Current Assignee: GPCP IP Holdings LLC
• Original Assignee: GPCP IP Holdings LLC
• Inventors: Lee, Jeffrey A.
• Primary Examiner(s): Khan, Amina S
• Application Number:
  US14/716,211
• Publication Number:
  US 20150337485A1
• Time in Patent Office: 1,813 Days
• CPC Class Codes: D04H 1/42 characterised by the use of certain kinds of fibres insofar as this use has no preponderant influence on the consolidation of the fleece
• CPC Class Codes: D04H 1/492 by fluid jet D04H1/49 takes precedence
• CPC Class Codes: D06L 4/13 using inorganic agents
• CPC Class Codes: D06L 4/30 using reducing agents
• CPC Class Codes: D21C 5/00 Other processes for obtaining cellulose, e.g. cooking cotton linters obtaining fibres for spinning D01C; Processes characterised by the choice of cellulose-containing starting materials
• CPC Class Codes: D21C 9/1084 with reducing compounds
• CPC Class Codes: D21C 9/147 with oxygen or its allotropic modifications D21C9/16 takes precedence
• CPC Class Codes: D21C 9/163 with peroxides
• CPC Class Codes: D21H 11/12 Pulp from non-woody plants or crops, e.g. cotton, flax, straw, bagasse
• CPC Class Codes: D21H 21/30 Luminescent or fluorescent substances, e.g. for optical bleaching D21H21/40 takes precedence
• CPC Class Codes: D21H 21/32 Bleaching agents bleaching cellulose pulp D21C9/10

Abstract

The present invention is directed to a method of increasing the brightness of non-wood fibers. The method comprises forming a mixture of non-wood fibers and exposing the mixture to a brightening agent, the brightening agent being a permanganate compound, an acid, or a combination of the permanganate compound and the acid. The resulting brightened fibers have a brightness greater than the fibers of the mixture before exposure as measured by MacBeth UV-C standard.

Claims

1. A method of increasing the brightness of non-wood fibers, the method comprising:

forming a mixture of non-wood fibers having a mean length of about 5 to about 95 millimeters (mm) and a consistency of about 5% to about 10%; and

exposing the mixture to a brightening agent, the brightening agent comprising a permanganate compound and an acid, having a pH of about 2 to about 3, and comprising about 1 to about 10 weight % of the permanganate compound based on dry weight of the non-wood fibers;

wherein the brightened fibers have a brightness greater than the fibers of the mixture before exposure as measured by MacBeth UV-C standard.

2. The method of claim 1, wherein the permanganate compound is selected from the group consisting of potassium permanganate, sodium permanganate, or any combination thereof.

3. The method of claim 1, wherein the acid is selected from the group consisting of acetic acid, carbonic acid, chloric acid, citric acid, formic acid, hydrobromic acid, hydrocyanic acid, hydroiodic acid, nitric acid, nitrous acid, oxalic acid, peraetic acid, phosphoric acid, phosphorous acid, sulfuric acid, or any combination thereof.

4. The method of claim 1, wherein the mixture is exposed to the brightening agent at a temperature in a range between about 20 and about 80°

C.

5. The method of claim 1, wherein the non-wood fibers are selected from the group consisting of flax fibers, hemp fibers, jute fibers, ramie fibers, nettle fibers, Spanish broom fibers, kenaf plant fibers, cotton fibers, or any combination thereof.

6. The method of claim 1, wherein the mixture is exposed to the brightening agent for a time in a range between about 1 and about 30 minutes.

7. The method of claim 1, further comprising exposing the brightened fibers to a reducing agent, a phosphate salt, or both the reducing agent and the phosphate salt.

8. The method of claim 7, wherein the reducing agent is selected from the group consisting of sodium hydrosulfite, potassium hydrosulfite, sodium sulfite, potassium sulfite, sodium sulfate, potassium sulfate, sodium bisulfite, potassium bisulfite, sodium metasulfite, potassium metasulfite, sodium borohydride, or any combination thereof.

9. The method of claim 7, wherein the reducing agent is present in a range between about 0.1 and about 2 wt. % based on the total weight of the fibers.

10. The method of claim 7, wherein the phosphate salt is selected from the group consisting of aluminum phosphate, aluminum triphosphate, calcium phosphate, calcium triphosphate, sodium phosphate, potassium phosphate, potassium triphosphate, sodium triphosphate, or any combination thereof.

11. The method of claim 7, wherein the phosphate salt is added to the mixture in a range between about 0.01 wt. % and about 1 wt. % based on the total weight of the fibers.

12. The method of claim 1, further exposing the brightened fibers to at least a second brightening agent.

13. The method of claim 12, wherein the at least second brightening agent is selected from the group consisting of a peroxide compound, an alkaline compound, a reducing agent, or any combination thereof.

14. The method of claim 13, wherein the peroxide compound is hydrogen peroxide.

15. The method of claim 14 further comprising exposing the brightened fibers to oxygen gas.

16. The method of claim 1, further comprising exposing the brightened fibers to a peroxide compound and then a reducing agent.

17. The method of claim 1, further comprising carding the brightened fibers to form a nonwoven fabric.

18. The method of claim 1, further comprising forming a nonwoven fabric comprising the brightened fibers.

19. The method of claim 18, wherein the nonwoven fabric is selected from the group consisting of a wet wipe, a dry wipe, or an impregnated wipe.

20. The method of claim 18, wherein the nonwoven fabric is selected from the group consisting of a tissue, a facial tissue, a bath tissue, a baby wipe, a personal care wipe, a personal protective wipe, a cosmetic wipe, a perinea wipe, a disposable washcloth, a kitchen wipe, an automotive wipe, a bath wipe, a hard surface wipe, a cleaning wipe, a disinfecting wipe, a glass wipe, a mirror wipe, a leather wipe, an electronics wipe, a lens wipe, a polishing wipe, a medical cleaning wipe, or a disinfecting wipe.

21. The method of claim 1, further comprising hydrogen tangling the brightened fibers to form a nonwoven fabric.

22. The method of claim 1, further comprising spun bonding the brightened fibers to form a nonwoven fabric.

23. The method of claim 1, further comprising forming a tissue or a paper comprising the brightened fibers.

24. The method of claim 1, further comprising, prior to forming the mixture, retting the non-wood fibers.

25. The method of claim 24, further comprising, subsequent to retting and prior to forming the mixture, scouring the non-wood fibers.

26. The method of claim 24, further comprising, subsequent to exposing the mixture to the brightening agent, scouring the non-wood fibers.

27. 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 about 5 to about 95 millimeters (mm) and a consistency of about 5-% to about 10%; and

exposing the mixture to a brightening agent to produce low-shive fibers, the brightening agent comprising a permanganate compound and an acid, having a pH of about 2 to about 3, and comprising about 1 to about 10 weight % of the permanganate compound based on dry weight of the non-wood fibers;

wherein the low-shive fibers have less visible shive content than the fibers of the mixture before exposure.

28. The method of claim 27, wherein the permanganate compound is selected from the group consisting of potassium permanganate, sodium permanganate, or any combination thereof.

29. The method of claim 27, wherein the acid is selected from the group consisting of acetic acid, carbonic acid, chloric acid, citric acid, formic acid, hydrobromic acid, hydrocyanic acid, hydroiodic acid, nitric acid, nitrous acid, oxalic acid, peraetic acid, phosphoric acid, phosphorous acid, sulfuric acid, or any combination thereof.

30. The method of claim 27, wherein the mixture is exposed to the brightening agent at a temperature in a range between about 20 and about 80°

C.

31. The method of claim 27, wherein the non-wood fibers are selected from the group consisting of flax fibers, hemp fibers, jute fibers, ramie fibers, nettle fibers, Spanish broom fibers, kenaf plant fibers, cotton fibers, or any combination thereof.

32. The method of claim 27, wherein the mixture is exposed to the brightening agent for a time in a range between about 1 and about 30 minutes.

33. The method of claim 27, further comprising exposing the brightened fibers to a reducing agent, a phosphate salt, or both the reducing agent and the phosphate salt.

34. The method of claim 33, wherein the reducing agent is selected from the group consisting of sodium hydrosulfite, potassium hydrosulfite, sodium sulfite, potassium sulfite, sodium sulfate, potassium sulfate, sodium bisulfite, potassium bisulfite, sodium metasulfite, potassium metasulfite, sodium borohydride, or any combination thereof.

35. The method of claim 33, wherein the reducing agent is present in a range between about 0.1 and about 2 wt. % based on the total weight of the fibers.

36. The method of claim 33, wherein the phosphate salt is selected from the group consisting of aluminum phosphate, aluminum triphosphate, calcium phosphate, calcium triphosphate, sodium phosphate, potassium phosphate, potassium triphosphate, sodium triphosphate, or any combination thereof.

37. The method of claim 33, wherein the phosphate salt is added to the fibers in a range between about 0.01 wt. % and about 2 wt. % based on the total weight of the mixture.

38. The method of claim 27, further exposing the brightened fibers to at least a second brightening agent.

39. The method of claim 38, wherein the at least second brightening agent is selected from the group consisting of a peroxide compound, an alkaline compound, a reducing agent, or any combination thereof.

40. The method of claim 39, wherein the peroxide compound is hydrogen peroxide.

41. The method of claim 39, further comprising exposing the brightened fibers to oxygen gas.

42. The method of claim 27, further comprising exposing the brightened fibers to a peroxide compound and then a reducing agent.

43. The method of claim 27, further comprising forming a nonwoven fabric comprising the brightened fibers.

44. The method of claim 43, wherein the nonwoven fabric is selected from the group consisting of a wet wipe, a dry wipe, or an impregnated wipe.

45. The method of claim 43, wherein the nonwoven fabric is selected from the group consisting of a tissue, a facial tissue, a bath tissue, a baby wipe, a personal care wipe, a personal protective wipe, a cosmetic wipe, a perinea wipe, a disposable washcloth, a kitchen wipe, an automotive wipe, a bath wipe, a hard surface wipe, a cleaning wipe, a disinfecting wipe, a glass wipe, a mirror wipe, a leather wipe, an electronics wipe, a lens wipe, a polishing wipe, a medical cleaning wipe, or a disinfecting wipe.

46. The method of claim 27, further comprising forming a tissue or a paper comprising the brightened fibers.