Soft tissue having reduced hydrogen bonding
The present invention provides a modified cellulosic fiber having reduced hydrogen bonding capabilities. The modified fiber formed in accordance with the present invention may be useful in the production of tissue products having improved bulk and softness. More importantly, the modified fiber is adaptable to current tissue making processes and may be incorporated into a tissue product to improve bulk and softness without an unsatisfactory reduction in tensile.
1. A method of forming a high bulk tissue web comprising the steps of mixing cellulosic fiber and a first organic solvent to form an fiber slurry, adjusting the pH of the fiber slurry with a caustic agent to a pH greater than about 9.0 thereby forming a alkaline fiber slurry; adding a cyanuric halide having general Formula (I) in the presence of a second organic solvent:
where R=chlorine, bromine, fluorine or iodine to the alkaline fiber slurry thereby forming a modified cellulosic fiber; washing the modified cellulosic fiber; and forming a tissue web from the washed modified cellulosic fiber, wherein the tissue web has a basis weight greater than about 10 grams per square meter (gsm) and a sheet bulk greater than about 6 cc/g.
2. The method of claim 1 wherein the caustic agent is selected from the group consisting hydroxide salts, carbonate salts and alkaline phosphate salts.
3. The method of claim 1 wherein the cyanuric halide is cyanuric chloride.
4. The method of claim 1 wherein the first organic solvent is selected from the group consisting of acetone, DMSO, DMF, acetonitrile, alcohols, polyalcohols, polyalcoholic ethers, pyridine, sulfolane, N-methyl pyrrolidinone and dioxane.
5. The method of claim 1 wherein the alkaline fiber slurry has a fiber consistency from about 5 to about 30 percent solids.
6. The method of claim 1 wherein the weight ratio of cellulosic fiber to cyanuric halide is from about 5:0.1 to about 5:1.
7. The method of claim 1 wherein the step of adding a cyanuric halide is carried out at a pH from about 9 to about 10 and at a temperature from about 0 to about 40° C.
8. The method of claim 1 wherein the cellulose fiber is either bleached northern softwood kraft pulp or bleached eucalyptus kraft pulp.
9. The method of claim 1 wherein the washed modified cellulosic fiber has a nitrogen content of at least about 0.2 weight percent.