Patent Application
20160032529
The invention relates to the functionalization of cellulose fibers by a process to render all or part of their surface to be hydrophobic. The invention includes methods for improving the dewatering and drainage practices involved in a paper making process, improving flow properties in papermaking nano/micro-fibrillated cellulose production processes resulting in improvements in energy expenditures associated with the current process and significantly reduced plugging problems during nano/micro-fibrillated cellulose production.
The process of making paper requires a large amount of energy, and nearly 80% of the required energy is consumed by paper drying. In particular, the sizeable proportion of energy necessary for paper drying is due to the process of drying by vaporization. From one viewpoint, the paper manufacturing process is essentially a very large dewatering operation through which network formation and consolidation of fibers occur. The ease with which water is released from furnish during the papermaking process affects both the production rate and energy consumption.
The entire dewatering process for sheet formation is a very complex sequence utilizing various physical phenomena. A low-solids cellulose fiber and water suspension (typically <1% consistency) is distributed on a permeable fabric belt in the paper machine. This belt can move at a speed of some 2000 meters per minute and the water drains out from the cellulosic fiber mixture by gravity and inertia. Next, a hydrofoil is used on the other side of the fabric opposite to the paper web being formed. This system is used to apply a short term vacuum impulse and to move the fibers to create drainage channels in the fiber web. Finally, perforated suction rolls and vacuum flat-boxes can be used to improve dewatering.
At this stage, the paper web has a solids content of about 15-25%. The next step involves a series of press nips where water is forced from the paper sheet into the voids of the continuous felts. After the press section, the solid content of the paper web is about 40-55%. Finally, the paper web moves through a series of steam heated rolls in order to vaporize most of the remaining water and eventually the moisture drops to a level of 4-8% which is the equilibrium moisture content of the finished paper product. All of these process steps require a substantial amount of energy and demand very high capital equipment investments and maintenance costs.
The cost of removing one unit of moisture in the forming, pressing, and drying sections of the paper making process is related by the ratios 1:5:220, respectively. Therefore, removing as much water as possible during the first two stages of the dewatering process greatly reduces the steam heated dryer load and improves papermaking economics provided that water removal is balanced with achieving desired end use requirements for the product produced such as formation. If water drainage could be improved even slightly, the impact would be considerable from both a financial and environmental perspective.
The paper industry has attempted to developed several different approaches to improve drainage at the wet end and also improve retention of some of the fines and fillers critical for paper making process. Retention-drainage (R/D) additives such as electrolytes, polymers or micro particle-polymer combinations and are commonly used to improve the first-pass retention of fines and fillers and drainage properties of furnish during the forming process.
However, using current methods known in the art of wet-end chemistry, fines become attached either to each other increasing the effective size or to fibers with the aid of R/D additives and can be agglomerated into larger particles. Effective surface area of fines is significantly reduced with this treatment, and the resulting flocs do not absorb as much water and obstruct the water flow from the mat. Fines attached to fibers do not move through the fiber mat to points where they would obstruct drainage channels (choke-points). Although several R/D additives have been investigated for their effects on the water removal on the forming process, doing so often causes one or more disadvantages at a subsequent step in the paper making process. For example, although polyethylenimine (PEI) increases the gravity drainage of the dewatering properties of newsprint furnish, vacuum drainage was decreased.
Although positive effects of various R/D additives on water drainage gravity-filtration of fiber suspensions have been suggested, parallel tests carried out with application of vacuum gave contradictory results. Rather than aiding in the dewatering, the cationic polymers when used alone or in combination with anionic acrylamide type retention aid resulted in substantially wetter fiber mats following a standardized application of vacuum. Moreover, a commonly used R/D additive, cationic polyacrylamide (CATPAM), can influence the dewatering properties of the papermaking furnish both positively and negatively, depending on the specific polymer used and the other additives. Highly charged cationic polyelectrolyte polymers are also used to reduce the inter-fiber friction which enhances the rate at which fibers slide past each other in the wet-end by partially covering the surface of the fibers (patch agglomeration) thus aiding drainage.
Microparticle systems have also been found to significantly improve the dewatering of the papermaking stock in neutral and alkaline systems as well as high speed paper machines. Enzyme treatment of cellulosic fibers also seem to improve the freeness of the papermaking stock by reducing the hydrodynamic surface area of fibers and by reducing fines content of the papermaking furnish. However, excessive treatment of fibers with enzymes have been found to increase the fines content of furnish, thus reducing the dewatering ability.
Positive effects of various dewatering aid treatments on the release of water during simple gravity-filtration of fiber suspensions have been suggested. However, similar tests with application of vacuum have been reported to give different results. In addition, using CATPAM can improve dewatering in the wire, but lesser water removal at the press section due to the formation of persistent fiber flocs by the chemical treatments. More rapid dewatering by gravity can be achieved due to the ability of water to flow quickly within the large void spaces that surround fiber flocs. Once most of the water has been removed by the application vacuum, the same void spaces allow air to rush ineffectively through the wet web, failing to maintain a pressure differential across the thickness of the sheet. In addition, sheets with highly flocculated fibers were found to require longer application heat in the drying section to remove the remaining water in the sheet by evaporation.
Therefore, there exists a need for new methods for improving the paper making process and/or the nano/micro-fibrillated cellulose production process by improving the dewatering techniques that are currently utilized. Since the cost effectiveness of the various physical means of dewatering far exceeds that of thermal drying, significant energy saving can be expected if the physical dewatering effectiveness is improved. Accordingly, the present disclosure provides improved methods for functionalizing cellulose fibers that exhibit desirable properties and provide related advantages for improvement in the paper making process and/or the nano/micro-fibrillated cellulose production process.
The methods comprising the functionalization of cellulose fibers according to the present disclosure provide several advantages compared to other methods known in the art. First, the methods improve the freeness and dewatering of the paper making process during the paper making process, leading to an increased production rate and reduced energy consumption. Second, the methods improve the suspension flow of the cellulosic fiber composition during the paper making process, leading to a lower amount of cellulosic fiber flocculation during the process.
Third, the methods improve the bulk of the resultant paper made during the process. Fourth, the methods improve the thickness of paper produced from a paper making process utilizing the described methods. Finally, the methods result in better wet web strength (runnability), ability to use of slower draining fibers, ability to increase refining without production loss, and reduced press load to maintain bulk.
The following numbered embodiments are contemplated and are non-limiting:
1. A method of functionalizing cellulose fibers in a paper making process or a nano/micro-fibrillated cellulose production process, said method comprising the steps of:
(a) obtaining a first plurality of cellulose fibers;
(b) functionalizing the first plurality of cellulose fibers by subjecting the cellulose fibers to a process in which all or part of the surface of one or more of the first plurality of cellulose fibers is rendered hydrophobic;
(c) optionally combining the first plurality of cellulose fibers with a second plurality of cellulose fibers, wherein the second plurality of cellulose fibers comprises non-functionalized cellulose fibers; and
(d) utilizing the first plurality of cellulose fibers, and optionally the second plurality of cellulose fibers, in the paper making process or the nano/micro-fibrillated cellulose production process.
2. A method of using functionalized cellulose fibers in a paper making process or a nano/micro-fibrillated cellulose production process, said method comprising the steps of:
(a) obtaining a first plurality of cellulose fibers;
(b) functionalizing the first plurality of cellulose fibers by subjecting the cellulose fibers to a process in which all or part of the surface of one or more of the first plurality of cellulose fibers is rendered hydrophobic;
(c) optionally combining the first plurality of cellulose fibers with a second plurality of cellulose fibers, wherein the second plurality of cellulose fibers comprises non-functionalized cellulose fibers; and
(d) using the first plurality of cellulose fibers, and optionally the second plurality of cellulose fibers, in the paper making process or the nano/micro-fibrillated cellulose production process.
3. A method of removing water in a paper making process or a nano/micro-fibrillated cellulose production process, said method comprising the steps of:
(a) obtaining a first plurality of cellulose fibers;
(b) functionalizing the first plurality of cellulose fibers by subjecting the cellulose fibers to a process in which all or part of the surface of one or more of the first plurality of cellulose fibers is rendered hydrophobic;
(c) optionally combining the first plurality of cellulose fibers with a second plurality of cellulose fibers, wherein the second plurality of cellulose fibers comprises non-functionalized cellulose fibers; and
(d) utilizing the first plurality of cellulose fibers, and optionally the second plurality of cellulose fibers, in the paper making process or the nano/micro-fibrillated cellulose production process, wherein the inclusion of the first plurality of cellulose fibers removes water from the paper making process or the nano/micro-fibrillated cellulose production process.
4. A method of improving drainage in a paper making process or a nano/micro-fibrillated cellulose production process, said method comprising the steps of:
(a) obtaining a first plurality of cellulose fibers;
(b) functionalizing the first plurality of cellulose fibers by subjecting the cellulose fibers to a process in which all or part of the surface of one or more of the first plurality of cellulose fibers is rendered hydrophobic;
(c) optionally combining the first plurality of cellulose fibers with a second plurality of cellulose fibers, wherein the second plurality of cellulose fibers comprises non-functionalized cellulose fibers; and
(d) utilizing the first plurality of cellulose fibers, and optionally the second plurality of cellulose fibers, in the paper making process or the nano/micro-fibrillated cellulose production process,
wherein the inclusion of the first plurality of cellulose fibers improves drainage in the paper making process or the nano/micro-fibrillated cellulose production process.
5. A method of improving dewatering of a cellulose fiber composition, said method comprising the steps of:
(a) obtaining a first plurality of cellulose fibers;
(b) functionalizing the first plurality of cellulose fibers by subjecting the cellulose fibers to a process in which all or part of the surface of one or more of the first plurality of cellulose fibers is rendered hydrophobic; and
(c) combining the first plurality of cellulose fibers with a second plurality of cellulose fibers to form the cellulose fiber composition, wherein the second plurality of cellulose fibers comprises non-functionalized cellulose fibers,
wherein the inclusion of the first plurality of cellulose fibers improves dewatering of the cellulose fiber composition.
6. A method of preparing a cellulose fiber composition comprising functionalized cellulose fibers, said method comprising the steps of:
(a) obtaining a first plurality of cellulose fibers;
(b) functionalizing the first plurality of cellulose fibers by subjecting the cellulose fibers to a process in which all or part of the surface of one or more of the first plurality of cellulose fibers is rendered hydrophobic; and
(c) combining the first plurality of cellulose fibers with a second plurality of cellulose fibers to form the cellulose fiber composition, wherein the second plurality of cellulose fibers comprises non-functionalized cellulose fibers.
7. A method of forming water channels in a cellulose fiber composition, said method comprising the steps of:
(a) obtaining a first plurality of cellulose fibers;
(b) functionalizing the first plurality of cellulose fibers by subjecting the cellulose fibers to a process in which all or part of the surface of one or more of the first plurality of cellulose fibers is rendered hydrophobic; and
(c) combining the first plurality of cellulose fibers with a second plurality of cellulose fibers to form the cellulose fiber composition, wherein the second plurality of cellulose fibers comprises non-functionalized cellulose fibers,
wherein the inclusion of the first plurality of cellulose fibers forms water
channels in the cellulose fiber composition.
8. The method of any one of the preceding clauses, wherein the paper making process results in formation of paper comprising the first plurality of cellulose fibers and optionally the second plurality of cellulose fibers.
9. The method of any one of the preceding clauses, wherein the method is performed in the paper making process.
10. The method of any one of the preceding clauses, wherein the method is performed in the nano/micro-fibrillated cellulose production process.
11. The method of any one of the preceding clauses, wherein the combination of step (c) results in a cellulose fiber composition comprising between 5% and 95% of functionalized cellulose fibers and between 5% and 95% of non-functionalized cellulose fibers.
12. The method of any one of the preceding clauses, wherein the combination of step (c) results in a cellulose fiber composition comprising between 10% and 90% of functionalized cellulose fibers and between 10% and 90% of non-functionalized cellulose fibers.
13. The method of any one of the preceding clauses, wherein the combination of step (c) results in a cellulose fiber composition comprising between 15% and 85% of functionalized cellulose fibers and between 15% and 85% of non-functionalized cellulose fibers.
14. The method of any one of the preceding clauses, wherein the combination of step (c) results in a cellulose fiber composition comprising between 25% and 75% of functionalized cellulose fibers and between 25% and 75% of non-functionalized cellulose fibers.
15. The method of any one of the preceding clauses, wherein the combination of step (c) results in a cellulose fiber composition comprising between 35% and 65% of functionalized cellulose fibers and between 35% and 65% of non-functionalized cellulose fibers.
16. The method of any one of the preceding clauses, wherein the combination of step (c) results in a cellulose fiber composition comprising about 1% of functionalized cellulose fibers and about 99% of non-functionalized cellulose fibers.
17. The method of any one of the preceding clauses, wherein the combination of step (c) results in a cellulose fiber composition comprising about 5% of functionalized cellulose fibers and about 95% of non-functionalized cellulose fibers.
18. The method of any one of the preceding clauses, wherein the combination of step (c) results in a cellulose fiber composition comprising about 10% of functionalized cellulose fibers and about 90% of non-functionalized cellulose fibers.
19. The method of any one of the preceding clauses, wherein the combination of step (c) results in a cellulose fiber composition comprising about 15% of functionalized cellulose fibers and about 85% of non-functionalized cellulose fibers.
20. The method of any one of the preceding clauses, wherein the combination of step (c) results in a cellulose fiber composition comprising about 25% of functionalized cellulose fibers and about 75% of non-functionalized cellulose fibers.
21. The method of any one of the preceding clauses, wherein the combination of step (c) results in a cellulose fiber composition comprising about 35% of functionalized cellulose fibers and about 65% of non-functionalized cellulose fibers.
22. The method of any one of the preceding clauses, wherein the combination of step (c) results in a cellulose fiber composition comprising about 50% of functionalized cellulose fibers and about 50% of non-functionalized cellulose fibers.
23. The method of any one of the preceding clauses, wherein the first plurality of cellulose fibers is pre-treated prior to functionalizing.
24. The method of any one of the preceding clauses, wherein the second plurality of cellulose fibers is pre-treated.
25. The method of any one of the preceding clauses, wherein the pre-treatment is a mechanical method that reduces fiber size of the first or second plurality of cellulose fibers.
26. The method of any one of the preceding clauses, wherein the pre-treatment is a enzymatic method that reduces fiber size of the first or second plurality of cellulose fibers.
27. The method of any one of the preceding clauses, wherein the pre-treatment is selected from the group consisting of beating, refining, cyrocrushing, grinding, electrospinning, and enzymatic pretreatment.
28. The method of any one of the preceding clauses, wherein the pre-treatment is beating.
29. The method of any one of the preceding clauses, wherein the pre-treatment is refining.
30. The method of any one of the preceding clauses, wherein the pre-treatment is cyrocrushing.
31. The method of any one of the preceding clauses, wherein the pre-treatment is grinding.
32. The method of any one of the preceding clauses, wherein the pre-treatment is electrospinning.
33. The method of any one of the preceding clauses, wherein the pre-treatment is enzymatic pretreatment.
34. The method of any one of the preceding clauses, wherein the cellulose fibers comprise hardwood cellulose fibers.
35. The method of any one of the preceding clauses, wherein the cellulose fibers comprise softwood cellulose fibers.
36. The method of any one of the preceding clauses, wherein the cellulose fibers comprise plant fibers.
37. The method of any one of the preceding clauses, wherein the cellulose fibers are bamboo fibers.
38. The method of any one of the preceding clauses, wherein the cellulose fibers are kenaf fibers.
39. The method of any one of the preceding clauses, wherein the cellulose fibers are reed fibers.
40. The method of any one of the preceding clauses, wherein the paper is selected from the group consisting of board, paperboard, fiberboard, cardboard, a printing paper grade, tissue paper, towel paper, a sanitary paper grade, a personal care paper grade, a superabsorbent paper grade, or any combination thereof.
41. The method of any one of the preceding clauses, wherein the paper is board.
42. The method of any one of the preceding clauses, wherein the paper is paperboard.
43. The method of any one of the preceding clauses, wherein the paper is fiberboard.
44. The method of any one of the preceding clauses, wherein the paper is cardboard.
45. The method of any one of the preceding clauses, wherein the paper is a printing paper grade.
46. The method of any one of the preceding clauses, wherein the paper is tissue paper.
47. The method of any one of the preceding clauses, wherein the paper is towel paper.
48. The method of any one of the preceding clauses, wherein the paper is a sanitary paper grade.
49. The method of any one of the preceding clauses, wherein the paper is a personal care paper grade.
50. The method of any one of the preceding clauses, wherein the paper is a superabsorbent paper grade.
51. The method of any one of the preceding clauses, wherein the hydrophobic process is performed according to a process selected from the group consisting of a liquid phase silanization, a gas phase silanization, plasma deposition, and an aqueous phase treatment scheme.
52. The method of any one of the preceding clauses, wherein the hydrophobic process comprises a liquid phase silanization.
53. The method of any one of the preceding clauses, wherein the hydrophobic process comprises a gas phase silanization.
54. The method of any one of the preceding clauses, wherein the hydrophobic process comprises plasma deposition.
55. The method of any one of the preceding clauses, wherein the hydrophobic process comprises an aqueous phase treatment scheme.
56. The method of any one of the preceding clauses, wherein the liquid phase silanization scheme comprises treating the cellulose fibers with an organosilane.
57. The method of any one of the preceding clauses, wherein the organosilane is octadecyltrichlorosilane.
58. The method of any one of the preceding clauses, wherein the liquid phase silanization scheme comprises treating the cellulose fibers with a fluorosilane.
59. The method of any one of the preceding clauses, wherein the liquid phase silanization scheme comprises treating the cellulose fibers with a composition comprises a silane dissolved in a solvent.
60. The method of any one of the preceding clauses, wherein the solvent is a hexane.
61. The method of any one of the preceding clauses, wherein the liquid phase silanization comprises octadecyltrichlorosilane and a hexane.
62. The method of any one of the preceding clauses, wherein the paper making process or the nano/micro-fibrillated cellulose production process is associated with improved drainage.
63. The method of any one of the preceding clauses, wherein the drainage is improved compared to a paper making process or a nano/micro-fibrillated cellulose production process without functionalized cellulose fibers.
64. The method of any one of the preceding clauses, wherein the paper making process or the nano/micro-fibrillated cellulose production process is associated with improved dewatering.
65. The method of any one of the preceding clauses, wherein the dewatering is improved compared to a paper making process or a nano/micro-fibrillated cellulose production process without functionalized cellulose fibers.
66. The method of any one of the preceding clauses, wherein the paper making process or the nano/micro-fibrillated cellulose production process is associated with improved freeness.
67. The method of any one of the preceding clauses, wherein the freeness is improved compared to a paper making process or a nano/micro-fibrillated cellulose production process without functionalized cellulose fibers.
68. The method of any one of the preceding clauses, wherein the paper making process or the nano/micro-fibrillated cellulose production process is associated with improved water retention value (WRV).
69. The method of any one of the preceding clauses, wherein the WRV is improved compared to a paper making process or a nano/micro-fibrillated cellulose production process without functionalized cellulose fibers.
70. The method of any one of the preceding clauses, wherein the paper making process or the nano/micro-fibrillated cellulose production process is associated with improved suspension flow.
71. The method of any one of the preceding clauses, wherein the improved suspension flow is characterized by a lower amount of cellulosic fiber flocculation.
72. The method of any one of the preceding clauses, wherein the suspension flow properties are improved compared to a paper making process or a nano/micro-fibrillated cellulose production process without functionalized cellulose fibers.
73. The method of any one of the preceding clauses, wherein the improved suspension flow is characterized by a lower amount of cellulosic fiber flocculation.
74. The method of any one of the preceding clauses, wherein the paper making process or the nano/micro-fibrillated cellulose production process is associated with improved bulk.
75. The method of any one of the preceding clauses, wherein the bulk is improved compared to a paper making process or a nano/micro-fibrillated cellulose production process without functionalized cellulose fibers.
76. The method of any one of the preceding clauses, wherein the paper making process produces paper with increased thickness.
77. The method of any one of the preceding clauses, wherein the thickness is increased compared to paper produced from a paper making process without functionalized cellulose fibers.
78. The method of any one of the preceding clauses, wherein the paper comprises an additional component or additive.
79. The method of any one of the preceding clauses, wherein the additional component or additive is functionalized.
80. The method of any one of the preceding clauses, wherein the additional component is selected from the group consisting of diatoms, diatomaceous earth, and porous nanosilica.
81. The method of any one of the preceding clauses, wherein the additional component is functionalized before its addition to the paper.
82. The method of any one of the preceding clauses, wherein the additional component is functionalized after its addition to the paper.
Various embodiments of the invention are described herein as follows. In one embodiment described herein, method of functionalizing cellulose fibers in a paper making process or a nano/micro-fibrillated cellulose production process is provided. The method comprises the steps of a) obtaining a first plurality of cellulose fibers; b) functionalizing the first plurality of cellulose fibers by subjecting the cellulose fibers to a process in which all or part of the surface of one or more of the first plurality of cellulose fibers is rendered hydrophobic; c) optionally combining the first plurality of cellulose fibers with a second plurality of cellulose fibers, wherein the second plurality of cellulose fibers comprises non-functionalized cellulose fibers; and d) utilizing the first plurality of cellulose fibers, and optionally the second plurality of cellulose fibers, in the paper making process or the nano/micro-fibrillated cellulose production process.
In another embodiment described herein, a method of using functionalized cellulose fibers in a paper making process or a nano/micro-fibrillated cellulose production process is provided. The method comprises the steps of a) obtaining a first plurality of cellulose fibers; b) functionalizing the first plurality of cellulose fibers by subjecting the cellulose fibers to a process in which all or part of the surface of one or more of the first plurality of cellulose fibers is rendered hydrophobic; c) optionally combining the first plurality of cellulose fibers with a second plurality of cellulose fibers, wherein the second plurality of cellulose fibers comprises non-functionalized cellulose fibers; and d) using the first plurality of cellulose fibers, and optionally the second plurality of cellulose fibers, in the paper making process or the nano/micro-fibrillated cellulose production process.
In yet another embodiment described herein, a method of removing water in a paper making process or a nano/micro-fibrillated cellulose production process is provided. The method comprises the steps of a) obtaining a first plurality of cellulose fibers; b) functionalizing the first plurality of cellulose fibers by subjecting the cellulose fibers to a process in which all or part of the surface of one or more of the first plurality of cellulose fibers is rendered hydrophobic; c) optionally combining the first plurality of cellulose fibers with a second plurality of cellulose fibers, wherein the second plurality of cellulose fibers comprises non-functionalized cellulose fibers; and d) utilizing the first plurality of cellulose fibers, and optionally the second plurality of cellulose fibers, in the paper making process or the nano/micro-fibrillated cellulose production process, wherein the inclusion of the first plurality of cellulose fibers removes water from the paper making process or the nano/micro-fibrillated cellulose production process.
In another embodiment described herein, a method of improving drainage in a paper making process or a nano/micro-fibrillated cellulose production process is provided. The method comprises the steps of a) obtaining a first plurality of cellulose fibers; b) functionalizing the first plurality of cellulose fibers by subjecting the cellulose fibers to a process in which all or part of the surface of one or more of the first plurality of cellulose fibers is rendered hydrophobic; c) optionally combining the first plurality of cellulose fibers with a second plurality of cellulose fibers, wherein the second plurality of cellulose fibers comprises non-functionalized cellulose fibers; and d) utilizing the first plurality of cellulose fibers, and optionally the second plurality of cellulose fibers, in the paper making process or the nano/micro-fibrillated cellulose production process, wherein the inclusion of the first plurality of cellulose fibers improves drainage in the paper making process or the nano/micro-fibrillated cellulose production process.
In yet another embodiment described herein, a method of improving dewatering of a cellulose fiber composition is provided. The method comprises the steps of a) obtaining a first plurality of cellulose fibers; b) functionalizing the first plurality of cellulose fibers by subjecting the cellulose fibers to a process in which all or part of the surface of one or more of the first plurality of cellulose fibers is rendered hydrophobic; and c) combining the first plurality of cellulose fibers with a second plurality of cellulose fibers to form the cellulose fiber composition, wherein the second plurality of cellulose fibers comprises non-functionalized cellulose fibers, wherein the inclusion of the first plurality of cellulose fibers improves dewatering of the cellulose fiber composition.
In another embodiment described herein, a method of preparing a cellulose fiber composition comprising functionalized cellulose fibers is provided. The method comprises the steps of a) obtaining a first plurality of cellulose fibers; b) functionalizing the first plurality of cellulose fibers by subjecting the cellulose fibers to a process in which all or part of the surface of one or more of the first plurality of cellulose fibers is rendered hydrophobic; and c) combining the first plurality of cellulose fibers with a second plurality of cellulose fibers to form the cellulose fiber composition, wherein the second plurality of cellulose fibers comprises non-functionalized cellulose fibers.
In yet another embodiment described herein, a method of forming water channels in a cellulose fiber composition is provided. The method comprises the steps of a) obtaining a first plurality of cellulose fibers; b) functionalizing the first plurality of cellulose fibers by subjecting the cellulose fibers to a process in which all or part of the surface of one or more of the first plurality of cellulose fibers is rendered hydrophobic; and c) combining the first plurality of cellulose fibers with a second plurality of cellulose fibers to form the cellulose fiber composition, wherein the second plurality of cellulose fibers comprises non-functionalized cellulose fibers, wherein the inclusion of the first plurality of cellulose fibers forms water channels in the cellulose fiber composition.
In the various embodiments, the method involves cellulose fibers in a paper making process or a nano/micro-fibrillated cellulose production process. As used herein, the term “cellulose fibers” refers to fibers from a plant or plant-based materials, including natural cellulose fibers, manufactured cellulose fibers, and the like. As used herein, the term “paper making process” refers to the manufacture of paper. The paper making process is well known in the art such as, for example, as described in Holik, Handbook of Paper and Board, Wiley-VCH, Second Edition (2013). As used herein, the term “nano/micro-fibrillated cellulose production process” is also well known in the art.
In the present disclosure, the functionalization of cellulose fibers is described. As used herein, the term “functionalization” refers to the utilization of any process that renders all or part of the surface of at least one cellulose fiber hydrophobic. The term “hydrophobic” has its general definition as known in the art, i.e. the physical property of a molecule that is repelled from, tends not to combine with, or is incapable of dissolving in water.
In some aspects, the paper making process results in the formation of paper comprising the first plurality of cellulose fibers and optionally the second plurality of cellulose fibers.
In various aspects, a first plurality of cellulose fibers is combined with a second plurality of cellulose fibers. In some embodiments, the combination results in a cellulose fiber composition comprising between 5% and 95% of functionalized cellulose fibers and between 5% and 95% of non-functionalized cellulose fibers. In other embodiments, the combination results in a cellulose fiber composition comprising between 10% and 90% of functionalized cellulose fibers and between 10% and 90% of non-functionalized cellulose fibers. In yet other embodiments, the combination of results in a cellulose fiber composition comprising between 15% and 85% of functionalized cellulose fibers and between 15% and 85% of non-functionalized cellulose fibers. In some embodiments, the combination results in a cellulose fiber composition comprising between 25% and 75% of functionalized cellulose fibers and between 25% and 75% of non-functionalized cellulose fibers. In other embodiments, the combination results in a cellulose fiber composition comprising between 35% and 65% of functionalized cellulose fibers and between 35% and 65% of non-functionalized cellulose fibers.
In some embodiments, the combination results in a cellulose fiber composition comprising about 1% of functionalized cellulose fibers and about 99% of non-functionalized cellulose fibers. In other embodiments, the combination results in a cellulose fiber composition comprising about 5% of functionalized cellulose fibers and about 95% of non-functionalized cellulose fibers. In yet other embodiments, the combination results in a cellulose fiber composition comprising about 10% of functionalized cellulose fibers and about 90% of non-functionalized cellulose fibers. In some embodiments, the combination results in a cellulose fiber composition comprising about 15% of functionalized cellulose fibers and about 85% of non-functionalized cellulose fibers. In other embodiments, the combination results in a cellulose fiber composition comprising about 25% of functionalized cellulose fibers and about 75% of non-functionalized cellulose fibers. In yet other embodiments, the combination results in a cellulose fiber composition comprising about 35% of functionalized cellulose fibers and about 65% of non-functionalized cellulose fibers. In some embodiments, the combination results in a cellulose fiber composition comprising about 50% of functionalized cellulose fibers and about 50% of non-functionalized cellulose fibers.
In various aspects, the first plurality of cellulose fibers is pre-treated prior to functionalizing. In other aspects, the second plurality of cellulose fibers is pre-treated. As used herein, the term “pre-treatment” refers to any method that reduces fiber size of the first plurality of cellulose fibers or the second plurality of cellulose fibers. The pre-treatment can be performed according to any procedure or process known in the art. In some embodiments, the pre-treatment is a mechanical method that reduces fiber size of the first or second plurality of cellulose fibers. In some embodiments, the pre-treatment is an enzymatic method that reduces fiber size of the first or second plurality of cellulose fibers. In other embodiments, the pre-treatment is selected from the group consisting of beating, refining, cyrocrushing, grinding, electrospinning, and enzymatic pretreatment. In one embodiment, the pre-treatment is beating, for example via a Valley beater. In other embodiments, the pre-treatment is refining. In yet other embodiments, the pre-treatment is cyrocrushing. In some embodiments, the pre-treatment is grinding. In other embodiments, the pre-treatment is electrospinning. In yet other embodiments, the pre-treatment is enzymatic pretreatment.
Any type of cellulose fibers can be utilized according to the present disclosure. In some embodiments, the cellulose fibers comprise hardwood cellulose fibers. In other embodiments, the cellulose fibers comprise softwood cellulose fibers. The terms “hardwood” and “softwood” are well known in the art and are given their understood meanings. In yet other embodiments, the cellulose fibers comprise plant fibers. In some embodiments, the cellulose fibers are bamboo fibers. In other embodiments, the cellulose fibers are kenaf fibers. In yet other embodiments, the cellulose fibers are reed fibers.
The “paper” of the paper making process, or the resultant paper made from the paper making process, includes all types of paper that can be made according to the processes known in the art. For example, in various aspects, paper is selected from the group consisting of board, paperboard, fiberboard, cardboard, a printing paper grade, tissue paper, towel paper, a sanitary paper grade, a personal care paper grade, a superabsorbent paper grade, or any combination thereof. In some embodiments, the paper is board. In other embodiments, the paper is paperboard. In yet other embodiments, the paper is fiberboard. In some embodiments, the paper is cardboard. In other embodiments, the paper is a printing paper grade. In yet other embodiments, the paper is tissue paper. In some embodiments, the paper is towel paper. In other embodiments, the paper is a sanitary paper grade. In yet other embodiments, the paper is a personal care paper grade, such as diapers, feminine hygiene products, fluff paper grades, and the like. In some embodiments, the paper is a superabsorbent paper grade.
In the present disclosure, cellulose fibers may be functionalized according to any process that renders all or part of the surface of at least one cellulose fiber hydrophobic. In some aspects, the hydrophobic process is performed according to a process selected from the group consisting of a liquid phase silanization, a gas phase silanization, plasma deposition, and an aqueous phase treatment scheme. Methods of rendering cellulose fibers to be hydrophobic are well known in the art. In some aspects, the hydrophobic process comprises a liquid phase silanization. In other embodiments, the hydrophobic process comprises a gas phase silanization. In yet other embodiments, the hydrophobic process comprises plasma deposition. In some embodiments, the hydrophobic process comprises an aqueous phase treatment scheme.
In various aspects, the liquid phase silanization scheme comprises treating the cellulose fibers with an organosilane. In certain aspects, the organosilane is octadecyltrichlorosilane. In other aspects, the liquid phase silanization scheme comprises treating the cellulose fibers with a fluorosilane. In yet other aspects, the liquid phase silanization scheme comprises treating the cellulose fibers with a composition comprises a silane dissolved in a solvent. In some embodiments, the solvent is a hexane. In one embodiment, the liquid phase silanization comprises octadecyltrichlorosilane and a hexane.
In some embodiments, the paper making process or the nano/micro-fibrillated cellulose production process is associated with improved drainage. The concept of drainage is well known in the art of paper making and nano/micro-fibrillated cellulose production. For example, “freeness” is standard measure of how quickly water is able to drain from a fiber furnish sample in the paper making process. In certain aspects, the drainage is improved compared to a paper making process or a nano/micro-fibrillated cellulose production process without functionalized cellulose fibers.
In some embodiments, the paper making process or the nano/micro-fibrillated cellulose production process is associated with improved dewatering. The concept of dewatering is well known in the art of paper making and is associated with any means that reduces the water used during the paper making process. In certain aspects, the dewatering is improved compared to a paper making process or a nano/micro-fibrillated cellulose production process without functionalized cellulose fibers.
In some embodiments, the paper making process or the nano/micro-fibrillated cellulose production process is associated with improved freeness. For example, freeness can be measured utilizing the Canadian Standard Freeness (CSF) method. In certain aspects, the freeness is improved compared to a paper making process or a nano/micro-fibrillated cellulose production process without functionalized cellulose fibers.
In some embodiments, the paper making process or the nano/micro-fibrillated cellulose production process is associated with improved water retention value. Water Retention Value (WRV) is a useful tool in evaluating the performance of pulps relative to dewatering behavior on the paper machine. The WRV method was established to provide standard values of centrifugal force, time of centrifuging, and sample preparation so that results can be compared between investigators at standard values. The WRV test can be used to estimate the maximum amount of water that can be removed from a certain furnish before the wet web leaves the press section of a paper machine. Examples of WRV measurements are described herein. In certain aspects, the WRV is improved compared to a paper making process or a nano/micro-fibrillated cellulose production process without functionalized cellulose fibers.
In some embodiments, the paper making process or the nano/micro-fibrillated cellulose production process is associated with improved suspension flow. The concept of suspension flow is well known in the art of paper making and nano/micro-fibrillated cellulose production, for example characterized by an observation of significantly fewer process problems such as plugging of the microfluidizer channels. In various aspects, the improved suspension flow is characterized by a lower amount of cellulosic fiber flocculation. As used herein, the term “flocculation” refers to a process of contact and adhesion whereby the particles of a dispersion form larger-size clusters. In certain aspects, the suspension flow properties are improved compared to a paper making process or a nano/micro-fibrillated cellulose production process without functionalized cellulose fibers. In certain aspects, the nano/micro-fibrillated cellulose production can utilize fiber samples prepared using a microfluidizer. After, the cellulose fiber composition is passed through the channels of the microfluidizer, the system can be evaluated to determine the presence or absence of plugging problems of the chambers of the microfluidizer. Advantageously, the nano/micro-fibrillated cellulose production utilizing the methods of the present disclosure are substantially free of problems that are typically observed in the traditional production of nanofibrillated cellulose (e.g., minimal plugging of the chambers is observed using the methods of the present disclosure).
In some embodiments, the paper making process or the nano/micro-fibrillated cellulose production process is associated with improved bulk. Paper bulk is well known in the art and is defined as the volume occupied by a given mass of paper (i.e., the inverse of density). The bulk of paper and paperboard is important because it contributes to the paper's thickness, also known as caliper. Increased paper thickness leads to higher rigidity or bending stiffness, an important measure of strength. Higher bulk also allows the papermaker to calendar the paper under greater pressure, which is done by passing it through rollers. In various aspects, the bulk is improved compared to a paper making process or a nano/micro-fibrillated cellulose production process without functionalized cellulose fibers.
In some embodiments, the paper making process produces paper with increased thickness. Increased paper thickness leads to higher rigidity or bending stiffness, an important measure of strength. In various aspects, the thickness is increased compared to paper produced from a paper making process without functionalized cellulose fibers.
In certain aspects of the present disclosure, a method of forming water channels in a cellulose fiber composition is provided. As used herein, the term “water channels” refers to any channel in the formed cellulose fiber composition through which water may pass, such as a channel in a mat.
In various aspects, other paper components or additives can be functionalized according to the methods described herein. In certain embodiments, components such diatoms, diatomaceous earth, other forms of porous nanosilica, and the like could be added to the paper matrix. These component could be functionalized according to the described methods either before or after their addition to the paper.
While the invention is susceptible to various modifications and alternative forms, specific embodiments are herein described in detail. It should be understood, however, that there is no intent to limit the invention to the particular forms described, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the scope of the invention.
Cellulose fibers can undergo pre-treatment prior to functionalization. In this example, bleached hardwood kraft and bleached softwood kraft pulps underwent pre-treatment by beating. The beating pre-treatment was performed by using a laboratory size Valley beater. The fibers were beaten until a pre-determined freeness testing value (530 ml) was reached. In general, beating causes fibers to flatten, shorten and internally and externally fibrillate. As shown in
After the pre-determined step, fiber mats were prepared from the beaten pulps by using Buchner funnel and filter paper. They were then allowed to air dry at ambient conditions.
Air dried fiber mats comprising cellulose fibers can be subjected to a process in which all or part of the surface of the cellulose fibers is rendered hydrophobic. For example, the cellulose fibers can be treated using a liquid phase silanization scheme. In this example, cellulose fibers were treated with octadecyltrichlorosilane (OTS) dissolved in one or more hexanes.
The functionalization process that results in the bonding of the OTS molecule to the cellulose surface can involve two reactions: 1) the hydrolysis of OTS with adventitious dissolved water to produce the reactive intermediate (a trisolanol) and 2) the condensation of the trisilanol with surface hydroxyl groups to form a grafted OTS moiety. The batch process begins with the preparation and conditioning of 2 liters of an OTS-hexane solution. This solution is allowed to condition by uptake of ambient humidity for approximately 10 minutes to cause the hydrolysis step of the functionalization mechanism.
Cellulose fibers as well as a rigorously cleaned piece of silicon (100) wafer are added to the solution and the mixture is allowed to react for a period of time. Periodically, the silicon (100) wafer piece is removed from the solution and checked for completeness of functionalization by contact angle goniometry. Once the water contact angle on the silicon (100) piece exceeds 105°, the functionalization is deemed to be complete. The functionalized fibers are separated from the spent OTS-hexane solution by Buchner funnel filtration and rinsing with neat hexane. The fibers are dried to bone-dryness in an oven at 77° C. prior to testing. The concentration of OTS in the OTS-hexane solution is determined based on an assumed specific surface area of cellulose fiber (100 m2/g) and complete surface coverage by functionalization.
For the system under present study, this amount was approximately 1.7 mmol OTS per air-dried gram of cellulose fiber to be treated. The amount of cellulose to be treated is weighed, and the appropriate amount of neat OTS is added to the 2 liters of hexane to prepare the OTS-hexane solution. A typical amount of cellulose fibers treated according to this example is 50 grams.
Freeness is an industry-standard measure of how quickly water is able to drain from a fiber furnish sample. In many cases, there is a direct correlation between freeness value and either 1) a target level of refining of pulp, or 2) the ease of drainage of white water from the wet web, especially in the early sections of a Fourdrinier former. Freeness of pulp (Canadian standard method) was measured according to T227 OM-09 (Tappi Stadards).
In this example, Canadian Standard Freeness (CSF) values were obtained for bleached hardwood and softwood pulp mixtures containing various percentage of functionalized fibers.
As demonstrated in
When pulp was pre-treated using a valley beater to reach 530 CSF, the highest increase in the CSF values was observed. Pre-treating pulp with a valley beater typically shortens the fibers and increases fibrillation. For both hardwood and softwood pulp types, the increased percentages of the functionalized fibers in the furnish mixture increased the CSF value considerably (increased to 43% for hardwood and increased to 38% for softwood). It was found that even a 5% addition of functionalized fiber into the fiber furnish increased the CSF values between 10 and 15 ml for both hardwood and softwood at both pre-treatment levels. Detailed data set from the CSF measurements can be found in Tables 1 and 2, which show a comparison of fibers before pre-treatment by beating with a Valley beater and after pre-treatment for hardwood fibers and for softwood fibers, respectively.
Taking into account the repeatability of the CSF value tests after the pre-treatment, both hardwood and softwood pulps behaved similarly. However, there is a slight CSF difference in the lower functionalized percentage of fibers comparing the pre-treated hardwood and softwood pulps. Before pre-treatment, the softwood fibers were approximately 2.5 mm long and about 70 μm wide and hardwood fibers before pre-treatment were approximately about 3 mm in length and 40 μm in width. Based on the observed results, it is clear that the CSF value correlates to the physical properties and dimensions of the fiber (combined effect of diameter, length and level of fibrillation). Even though after the pre-treatment of both pulp types the CSF value was the same, the difference of the tail of the curve between hardwood and softwood point out that the fiber dimensions and the level of fibrillation are different in both pulp types (see
The hydrophobic fibers that have less surface area or less external reach due to fibrillation do appear to create less drainage improving effect in the pulp. Due to the hydrophobic nature surrounding the treated fibers reduction of the inter-fiber friction, additional fiber movement in furnish, and in general reorientation of fibers may be expected. This activity would be anticipated to aid gravity drainage of fiber suspension. Furthermore, this may be indirect evidence that the phenomenology of the drainage improvement is very similar to the highly charged cationic polyelectrolyte polymers that are used in reducing the inter-fiber friction in the wet-end.
Water Retention Value (WRV) is a useful tool in evaluating the performance of pulps relative to dewatering behavior on the paper machine. The WRV method was established to provide standard values of centrifugal force, time of centrifuging, and sample preparation so that results can be compared between investigators at standard values. The WRV test can be used to estimate the maximum amount of water that can be removed from a certain furnish before the wet web leaves the press section of a paper machine.
The basic WRV measurement procedure was the following: the wet specimen weight (W5) is obtained by subtracting the weight of the filtering crucible or specimen holder alone (W1) from the weight of the specimen and holder after centrifuging (W2). The dry specimen weight (W3) is measured by subtracting the weight of the filtering crucible or specimen holder alone (W1) from the weight of the specimen and holder after drying (W4). Finally the water retention value is reported to three significant figures, as the ratio of grams of water to grams of fiber after centrifuging according the following equation:
WRV=(W2−W4)/(W4−W1)=(W5−W3)/W3.
WRV testing was done also using Valley beating as the pre-treatment. The starting CSF values for both hardwood and softwood were about 530 ml. Since the pulp mixtures with no pre-treatment had limited effect on freeness values WRV tests were not performed on the pulp mixtures with no pre-treatment. In both CSF and WRV testing, it was determined that reaching exactly the same CSF value from pre-treatment was difficult and therefore an error of about 2-3% was observed. However, this was not expected to create uncertainties as the overall repeatability relatively to the starting CSF value has been reported to be 3-5% with CSF of 530 ml.
WRV is a standardized empirical measure of the capacity of a test pad of fibers to hold and retain water. It is well known that WRV-value increases upon the increase in beating with a Valley beater because it causes flattening of fibers, partial removal of primary wall, and loosening of internal structure. This promotes fiber swelling and renders fibers soft and flexible. The swelling phenomenon occurs concurrently with the development of external fibrils that involves loosening of the fibrils and rising of the finer microfibrils on the surfaces of the fibers which results in a very large increase in surface area on the fibers. As a result, beaten fibers effectively hold water. In the paper making process, the WRV value of papermaking furnishes is known to increase with increasing refining and increasing pH. Higher pH values promote fiber swelling and water access to swollen fibers is considerably easier. Also, WRV value tends to decrease when kraft fibers are dried and re-slurried due to increased stiffness of the fibers.
As shown in
The higher WRV from softwood fibers confirm the results from the CSF testing. Thus, the WRV and CSF tests both confirm the effectiveness of our approach to improve the drainage phenomena. Test results demonstrate the effect to be related to the external fibrils that are not able to absorb water and are functioning as highly increased effective area for reduced inter-fiber friction and internal sliding movements and reorientation that effectively increases drainage.
Sediment volume formation behavior of the functionalized and non-functionalized fibers was investigated according to the following procedure. Three (3) grams of fibers was mixed in 997 ml water and were then disintegrated to individual fibers using disintegrator for 3 minutes. Thereafter, a 100 ml sample was taken from the slurry and poured in to a 100 ml graduated cylinder. Photographs were taken and fiber levels were recorded at specified time intervals.
Sediment volume formation behaviors of the 100% functionalized and non-functionalized fibers are shown in
As shown in
As shown in
The fiber samples can be prepared for nano/micro-fibrillated cellulose production using a microfluidizer. Briefly, the procedure for microfluidizer application in nanofibrillated cellulose production is as follows. First, 80% pretreated (2 hour PFI refining) and TEMPO oxidized fiber is mixed with 20% functionalized (hydrophobic) fiber. Then, the mixture is passed through the channels of the microfluidizer. Subsequently, the system can be evaluated to determine the presence or absence of plugging problems of the chambers of the microfluidizer.
According to the methods of the present disclosure, the observed results of the example demonstrate that the microfluidizer is advantageously substantially free of problems for the production of nanofibrillated cellulose (e.g., minimal plugging of the chambers).
Paper samples (i.e., “handsheets”) can be made according to the art-recognized TAPPI T-205 procedure (i.e., TAPPI Test Method No. T-205, entitled “Forming handsheets for physical tests of pulp”). In this example, paper samples contained 100% non-functionalized fibers, 100% functionalized fibers, or a mixture of 5% functionalized fibers and 95% non-functionalized fibers. The calipers (i.e., thickness) of the resultant paper samples can be measured according to the art-recognized TAPPI T 411 procedure (i.e., TAPPI Test Method No. T 411, entitled “Thickness (caliper) of paper, paperboard, and combined board”).
The observed thickness (caliper) values of the paper samples created according to a paper making process utilizing methods of the present disclosure are shown in Table 5 (hardwood) and Table 6 (softwood) below.
As shown in Table 5, paper samples produced using functionalized hardwood cellulose fibers demonstrate an increased thickness compared to paper samples produced using non-functionalized hardwood cellulose fibers. The thickness values increased with a larger percentage of functionalized cellulose fibers in the composition. In particular, paper samples produced using 5% functionalized hardwood cellulose fibers show a 2.26% increase in thickness compared to paper samples produced using non-functionalized hardwood cellulose fibers. Moreover, paper samples produced using 100% functionalized hardwood cellulose fibers show a 29.0% increase in thickness compared to paper samples produced using non-functionalized hardwood cellulose fibers.
As shown in Table 6, paper samples produced using functionalized softwood cellulose fibers demonstrate an increased thickness compared to paper samples produced using non-functionalized hardwood cellulose fibers. In particular, paper samples produced using 5% functionalized hardwood cellulose fibers show a 5.83% increase in thickness compared to paper samples produced using non-functionalized hardwood cellulose fibers.
In summary, by using methods of the present disclosure, the thickness of paper samples can be increased for paper products made from both hardwood and softwood.
This application claims the benefit under 35 USC §119(e) of U.S. Provisional Application Ser. No. 61/783,669, filed on Mar. 14, 2013, the entire disclosure of which is incorporated herein by reference.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US14/28398 | 3/14/2014 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 61783669 | Mar 2013 | US |
