Absorbent sheet having regenerated cellulose microfiber network
View Patent ↗An absorbent paper sheet for tissue or towel includes from about 99 percent to about 70 percent by weight of cellulosic papermaking fiber and from about 1 percent to about 30 percent by weight fibrillated regenerated cellulose microfiber which was regenerated form a cellulosic dope utilizing a tertiary amine N-oxide solvent or an ionic liquid. Fibrillation of the microfiber is controlled such that it has a reduced coarseness and a reduced freeness as compared with unfibrillated regenerated cellulose microfiber from which it is made and provides at least one of the following attributes to the absorbent sheet: (a) the absorbent sheet exhibits an elevated SAT value and an elevated wet tensile value as compared with a like sheet prepared without fibrillated regenerated cellulose microfiber; (b) the absorbent sheet exhibits an elevated wet/dry CD tensile ratio as compared with a like sheet prepared without fibrillated regenerated cellulose microfiber; (c) the absorbent sheet exhibits a lower GM Break Modulus than a like sheet having like tensile values prepared without fibrillated regenerated cellulose microfiber; or (d) the absorbent sheet exhibits an elevated bulk as compared with a like sheet having like tensile values prepared without fibrillated regenerated cellulose microfiber. In some embodiments, the pulp is pre-treated with debonder to enhance the wet/dry CD tensile ratio of the sheet.
1. An absorbent paper sheet for tissue or towel comprising from about 99 percent to about 70 percent by weight of pulp-derived papermaking fiber and from about 1 to about 30 percent by weight of fibrillated regenerated cellulose microfiber prepared from a cellulosic dope of dissolved cellulose comprising a solvent selected from: tertiary amine N-oxides; cellulose dissolving imidazolium salts; cellulose dissolving pyridinium salts; cellulose dissolving pyridazinium salts; cellulose dissolving pyrimidinium salts; cellulose dissolving pyrazinium salts; cellulose dissolving pyrazolium salts; cellulose dissolving oxazolium salts; cellulose dissolving 1,2,3-triazolium salts; cellulose dissolving 1,2,4-triazolium salts; cellulose dissolving thiazolium salts; cellulose dissolving piperidinium salts; cellulose dissolving pyrrolidinium salts; cellulose dissolving quinolinium salts; and cellulose dissolving isoquinolinium, salts, the microfiber having a CSF value of less than 100 ml, wherein the fibrillated regenerated cellulose has a weight average diameter of less than 1 micron, a weight average length of less than 400 microns and a fiber count of greater than 2 billion fibers/gram.
2. The absorbent paper sheet for tissue or towel according to claim 1 , wherein the fibrillated regenerated cellulose microfiber has a weight avenge diameter of less than 0.5 microns, a weight average length of less than 300 microns and a fiber count of greater than 10 billion fibers/gram.
3. The absorbent paper sheet for tissue or towel according to claim 1 , wherein the fibrillated regenerated cellulose microfiber has a weight average diameter of less than 0.25 microns, a weight average length of less than 200 microns and a fiber count of greater than 50 billion fibers/gram.
4. The absorbent sheet according to claim 1 , wherein the fibrillated regenerated cellulose microfiber has a CSF value of less than 100 ml.
5. The absorbent sheet according to claim 1 , wherein the fibrillated regenerated cellulose microfiber has a CSF value of less than 50 ml.
6. The absorbent sheet according to claim 1 , wherein the fibrillated regenerated cellulose microfiber has a CSF value of less than 25 ml.
7. The absorbent sheet according to claim 1 , wherein the fibrillated regenerated cellulose microfiber has a CSF value of 0 ml.
8. An absorbent cellulosic sheet, comprising:
(a) cellulosic pulp-derived papermaking fibers in an amount of from about 70% up to about 98% by weight; and
(b) fibrillated regenerated cellulose fibers in an amount of from about 30% to about 2% by weight, wherein the regenerated cellulose is prepared from a cellulosic dope of dissolved cellulose comprising a solvent selected from: tertiary amine N-oxides; cellulose dissolving imidazolium salts; cellulose dissolving pyridinium salts; cellulose dissolving pyridazinium salts; cellulose dissolving pyrimidinium salts; cellulose dissolving pyrazinium salts; cellulose dissolving pyrazolium salts; cellulose dissolving oxazolium salts; cellulose dissolving 1,2,3-triazolium salts; cellulose dissolving 1,2,4-triazolium salts; cellulose dissolving thiazolium salts; cellulose dissolving piperidinium salts; cellulose dissolving pyrrolidinium salts; cellulose dissolving quinolinium salts; and cellulose dissolving isoquinolinium salts,
said fibrillated regenerated cellulose fibers having a number average fibril width of less than about 4 μm, and wherein the number average fiber length of the fibrillated regenerated cellulose fibers is less than about 250 micrometers.
9. The absorbent cellulosic sheet of claim 8 , wherein the number avenge fiber length of the fibrillated regenerated cellulose fibers is less then about 150 micrometers.
10. The absorbent cellulosic sheet of claim 8 , wherein the number average fiber length of the fibrillated regenerated cellulose fibers is less than about 100 micrometers.
11. The absorbent cellulosic sheet of claim 8 , wherein the number avenge fiber length of the fibrillated regenerated cellulose fibers is less than about 75 micrometers.
12. The absorbent sheet according to claim 8 , wherein the fibrillated regenerated cellulose microfiber has a CSF value of less than 100 ml.
13. The absorbent sheet according to claim 8 , wherein the fibrillated regenerated cellulose microfiber has a CSF value of less than 50 ml.
14. The absorbent sheet according to claim 8 , wherein the fibrillated regenerated cellulose microfiber has a CSF value of less than 25 ml.
15. The absorbent sheet according to claim 8 , wherein the fibrillated regenerated cellulose microfiber has a CSF value of 0 ml.
16. An absorbent cellulosic sheet, comprising:
(a) cellulosic pulp-derived papermaking fibers in an amount of from about 70% up to about 98% by weight; and
(b) fibrillated regenerated cellulose fibers in an amount of from about 30% to about 2% by weight, and wherein the regenerated cellulose is prepared from a cellulosic dope of dissolved cellulose comprising a solvent selected from: tertiary amine N-oxides; cellulose dissolving imidazolium salts; cellulose dissolving pyridinium salts; cellulose dissolving pyridazinium salts; cellulose dissolving pyrimidinium salts; cellulose dissolving pyrazinium salts; cellulose dissolving pyrazolium salts; cellulose dissolving oxazolium salts; cellulose dissolving 1,2,3-triazolium salts; cellulose dissolving 1,2,4-triazolium salts; cellulose dissolving thiazolium salts; cellulose dissolving piperidinium salts; cellulose dissolving pyrrolidinium salts; cellulose dissolving quinolinium salts; and cellulose dissolving isoquinolinium salts,
said fibrillated regenerated cellulose fibers having a number average fibril length of less than about 250 micrometers.
17. The absorbent cellulosic sheet of claim 16 , wherein the number average fiber length of the fibrillated regenerated cellulose fibers is less than about 150 micrometers.
18. The absorbent cellulosic sheet of claim 16 , wherein the number average fiber length of the fibrillated regenerated cellulose fibers is less than about 100 micrometers.
19. The absorbent cellulosic sheet of claim 16 , wherein the number average fiber length of the fibrillated regenerated cellulose fibers is less than about 75 micrometers.
20. The absorbent sheet according to claim 16 , wherein the fibrillated regenerated cellulose microfiber has a CSF value of less than 100 ml.
21. The absorbent sheet according to claim 16 , wherein the fibrillated regenerated cellulose microfiber has a CSF value of less than 50 ml.
22. The absorbent sheet according to claim 16 , wherein the fibrillated regenerated cellulose microfiber has a CSF value of less than 25 ml.
23. The absorbent sheet according to claim 16 , wherein the fibrillated regenerated cellulose microfiber has a CSF value of 0 ml.