Methods for producing a cellulosic fiber having a high curl index and acquisition and distribution layer containing same
View Patent ↗A process for producing cellulosic fiber with a high curl index is disclosed. The process can include mechanically treating and chemically crosslinking kraft pulp. The mechanical treatment of the pulp can include convolving and mechanically treating a pulp at in a plug screw and steam tube at temperatures above 100° C. and pressures above 3 bar. The mechanically treated pulp can be crosslinked with a crosslinking agent. The product fiber can exhibit a curl index of greater than 0.35, and can be at least 50% higher than the initial curl of the starting pulp material.
1. A process for preparing a high-curl kraft pulp, comprising
mechanically treating a chemical pulp by
passing pulp through a plug screw
passing the pulp through a steam tube in less than about 6 minutes;
pressurizing the pulp while in the plug screw with steam at a temperature above 100° C. and a pressure greater than 2bar;
treating the mechanically processed kraft pulp with a crosslinking agent;
drying the processed kraft pulp at a temperature above 100° C.; and
curing the processed kraft pulp at a temperature of at least about 140° C. to produce the high-curl pulp.
2. The process of claim 1 , wherein the pulp is at a pressure greater than 3 bar.
3. The process of claim 1 , wherein the pulp is at a pressure of 3 to 5 bar.
4. The process of claim 1 , wherein the pulp resides in the steam tube for 30 seconds to 5 minutes.
5. The process of claim 1 , wherein the pulp resides in the steam tube for about 30 seconds to 4 minutes.
6. The process of claim 1 , wherein the pulp resides in the steam tube for about 2 to 4 minutes.
7. The process of claim 1 , wherein the pulp is at a pressure of 3-5 bars at a temperature greater than 100° C. for 30 seconds to 4 minutes.
8. The process of claim 1 , wherein the crosslinking agent is selected from the group consisting of citric acid and glutaraldehyde.
9. The process of claim 8 , wherein the pulp is treated with citric acid in an amount of 0.5% to 10% by weight to the kraft pulp solids content.
10. The process of claim 9 , wherein the pulp is treated with citric acid in an amount of 1 to 5% by weight to the kraft pulp solids content.
11. The process of claim 1 , wherein the pulp is treated with a crosslinking agent in an amount of 0.5% to 10% by weight of a kraft pulp solids content.
12. The process of claim 1 , wherein the high curl kraft pulp has a final curl index of at least about 0.35.
13. The process of claim 1 , wherein the high curl kraft pulp has a final curl index of at least about 0.40.
14. The process of claim 1 , wherein the curing temperature is at least about 150° C.
15. The process of claim 1 , wherein the high curl kraft pulp has a final curl index at least 100% higher than an initial curl index of the chemical pulp.
16. The process of claim 1 , wherein the high curl kraft pulp has a final curl index at least 150% higher than an initial curl index of the chemical pulp.
17. The process of claim 1 , wherein the high curl kraft pulp has a final curl index at least 200% higher than an initial curl index of the chemical pulp.
18. The process of claim 1 , wherein the high curl kraft pulp has a final curl index of at least about 0.43.
19. The process of claim 1 , wherein the high curl kraft pulp has a final curl index of at least about 0.46.