Crosslinked cellulose as precursor in production of high-grade cellulose derivatives and related technology
A pulp in accordance with a particular embodiment includes crosslinked cellulose fibers. The pulp can have high brightness, reactivity, and intrinsic viscosity. The pulp, therefore, can be well suited for use as a precursor in the production of low-color, high-viscosity cellulose derivatives. A method in accordance with a particular embodiment of the present technology includes forming a pulp from a cellulosic feedstock, bleaching the pulp, crosslinking cellulose fibers within the pulp while the pulp has a high consistency, and drying the pulp. The bleaching process can reduce a lignin content of the pulp to less than or equal to 0.09% by oven-dried weight of the crosslinked cellulose fibers. Crosslinking the cellulose fibers can include exposing the cellulose fibers to a glycidyl ether crosslinker having two or more glycidyl groups and a molecular weight per epoxide within a range from 140 to 175.
1. A method, comprising:
crosslinking bleached cellulose fibers within a pulp while the pulp has a consistency greater than or equal to 12%; and
drying the pulp after said crosslinking, wherein the dried pulp has:
a resultant carboxymethyl cellulose (CMC) viscosity greater than or equal to 60 centipoise (cP),
a brightness greater than or equal to 75%, and
a water retention value (WRV) greater than or equal to 1.1 g/g.
2. The method of claim 1 , wherein crosslinking the bleached cellulose fibers includes crosslinking the bleached cellulose fibers while the pulp has a consistency greater than or equal to 15%.
3. The method of claim 1 , wherein crosslinking the bleached cellulose fibers increases a WRV of the dried pulp.
4. The method of claim 1 , wherein crosslinking the bleached cellulose fibers includes exposing the bleached cellulose fibers to a glycidyl ether crosslinker having two or more glycidyl groups.
5. The method of claim 1 , wherein crosslinking the bleached cellulose fibers includes exposing the bleached cellulose fibers to a crosslinker, and wherein the crosslinker has a weight average molecular weight within a range from 174 to 500.
6. The method of claim 1 , wherein crosslinking the bleached cellulose fibers includes exposing the bleached cellulose fibers to a crosslinker, and wherein the crosslinker has a molecular weight per epoxide within a range from 140 to 175.
7. The method of claim 1 , wherein crosslinking the bleached cellulose fibers includes exposing the bleached cellulose fibers to a crosslinker, and wherein the crosslinker includes a first glycidyl group, a second glycidyl group, and either three or four linear chain carbon atoms between the first and second glycidyl groups.
8. The method of claim 1 , further comprising blending the pulp with a dissolving grade pulp having a cellulose content greater than 90% by oven dried weight to form a blended pulp after crosslinking the bleached cellulose fibers, wherein drying the pulp includes drying the blended pulp.
9. The method of claim 1 , wherein the pulp during crosslinking comprises Kraft fibers.
10. The method of claim 1 , wherein the dried pulp comprises a lignin content of less than or equal to 0.09% by oven-dried weight of the crosslinked cellulose fibers.
11. The method of claim 1 , wherein the dried pulp has:
a resultant CMC viscosity greater than or equal to 60 cP;
a brightness greater than or equal to 75%; and
a WRV greater than or equal to 1.0 g/g.
12. The method of claim 1 , wherein the dried pulp is at least partially insoluble in cupriethylenediamine (cuen).
13. The method of claim 1 , wherein the dried pulp comprises greater than or equal to 10% hemicellulose by oven-dried weight of the crosslinked cellulose fibers.
14. The method of claim 1 , wherein the dried pulp has a resultant CMC viscosity greater than or equal to 90 cP.
15. The method of claim 1 , wherein the dried pulp has a resultant CMC color less than or equal to 5.
16. The method of claim 1 , wherein the dried pulp has a resultant CMC turbidity less than or equal to 25 Nephelometric Turbidity Units (NTU).
17. The method of claim 1 , wherein the dried pulp has a WRV less than or equal to 1.4 g/g.
18. The method of claim 1 , wherein the dried pulp has an R18 value greater than or equal to 88.
19. The method of claim 18 , wherein the dried pulp has an R18 value less than or equal to 92.
20. The method of claim 1 , wherein the dried pulp has a falling ball viscosity greater than or equal to 200 cP.
21. The method of claim 1 , wherein the dried pulp has no cellulose-II as determined by X-ray crystallography.
22. The method of claim 1 , wherein the dried pulp has a crystallinity index less than or equal to 80%.
23. The method of claim 1 , wherein the dried pulp has a crystallinity index less than or equal to 75%.
24. The method of claim 1 , wherein the dried pulp has a brightness greater than or equal to 80%.
25. The method of claim 1 , wherein the dried pulp has a brightness less than or equal to 88.5%.
26. The method of claim 1 , wherein the dried pulp has a basis weight of greater than or equal to 500 g/m 2 .
27. The method of claim 1 , wherein the dried pulp has a basis weight less than or equal to 1200 g/m 2 .
28. The method of claim 1 , wherein the dried pulp has a density greater than or equal to 0.20 g/cm 3 .
29. The method of claim 1 , wherein the dried pulp has a freeness greater than or equal to 700 mL.
30. The method of claim 1 , wherein the crosslinked cellulose fibers include crosslinks derived from a glycidyl ether crosslinker having two or more glycidyl groups.
31. The method of claim 1 , wherein the crosslinked cellulose fibers include crosslinks derived from a glycidyl ether crosslinker having a weight average molecular weight within a range from 174 to 500.
32. The method of claim 1 , wherein the crosslinked cellulose fibers include crosslinks derived from a glycidyl ether crosslinker having a weight per epoxide within a range from 140 to 175.
33. The method of claim 1 , wherein the crosslinked cellulose fibers include crosslinks derived from a glycidyl ether crosslinker having a first glycidyl group, a second glycidyl group, and either three or four linear chain carbon atoms between the first and second glycidyl groups.
34. The method of claim 1 , wherein the crosslinked cellulose fibers are derived from wood.
35. The method of claim 1 , wherein dried pulp has:
an R18 value in a range of 90% to 92.8%;
a kink index in a range of 2.6 mm −1 to 3.2 mm −1 ; and
a curl index in a range of 0.261 to 0.341.
36. The method of claim 1 , wherein the dried pulp has:
a hemicellulose content in a range of 6 wt. % to 20 wt. %;
a WRV in a range of 1.0 g/g to 1.5 g/g; and
a kink index in a range of 2.6 mm −1 to 3.2 mm −1 .
37. The method of claim 1 , wherein the dried pulp has an R18 value in a range of 90% to 92.8%.
38. The method of claim 1 , wherein the dried pulp has a curl index in a range of 0.261 to 0.341.
39. The method of claim 1 , wherein the dried pulp has a resultant CMC viscosity in a range of 60 cP to about 500 cP.