Treated fibers and fibrous structures comprising the same
The present invention provides a treated fiber having reduced hydrogen bonding capabilities, which may be useful in the production of tissue products having improved bulk and softness. The treated fiber comprises a water-insoluble inorganic compound that is generated in situ by reacting at least one compound selected from the group consisting of a silicate, a silyl, a silane, and an alkaline metal and a precipitation agent in the presence of the fiber at or above the critical fiber consistency.
1. A method of increasing the bulk of a tissue web comprising the steps of:
a. dispersing a first fiber in an aqueous solvent to form a fiber slurry,
b. adding a first reagent selected from the group consisting of a silicate, a silyl, a silane, and an alkaline metal to the first fiber slurry,
c. partially dewatering the first fiber slurry to a consistency equal to, or greater than, about 15 percent to form a partially dewatered fiber slurry,
d. adding a precipitation agent to the partially dewatered first fiber slurry to form a treated fiber comprising a water-insoluble inorganic; and
e. forming a tissue web from the treated fiber, wherein the tissue web has a sheet bulk greater than about 5.0 cc/g and a basis weight less than about 60 gsm.
2. The method of claim 1 wherein the partially dewatered first fiber slurry has a consistency from about 20 to about 40 percent.
3. The method of claim 1 wherein the first reagent is a water-soluble compound having a water solubility of greater than about 100 mg/mL at 25° C.
4. The method of claim 3 wherein the water-soluble compound is a silicate or an alkaline metal.
5. The method of claim 3 wherein the water-soluble compound is a silicate selected from the group consisting of sodium silicate, potassium silicate, lithium silicate and quaternary ammonium silicates.
6. The method of claim 3 wherein the water-soluble compound is a sodium silicate having a SiO:Na 2 O ratio from about 2:1 to about 4:1.
7. The method of claim 1 wherein the first reagent is either a silane or a silyl.
8. The method of claim 1 wherein the first reagent is a silane selected from the group consisting of a tetramethoxysilane, tetraethoxysilane (TEOS), tetrapropoxysilane, tetraisopropoxy silane, or combinations thereof.
9. The method of claim 1 wherein the treated fiber comprises at least about 5,000 ppm water-insoluble inorganic selected from group consisting of silicone, aluminum and zinc.
10. The method of claim 1 wherein at least about 75 percent of the water-insoluble inorganic is retained when the treated fiber is dispersed in water at 20° C.
11. The method of claim 1 wherein the tissue web has a basis weight from about 10 to about 60 gsm and a sheet bulk greater than about 10 cc/g.
12. The method of claim 1 wherein the amount of treated fiber is from about 5 to about 80 percent of the weight of the web.
13. The method of claim 1 wherein the bulk of the tissue web is at least about 25 percent greater than the bulk of a similarly manufactured tissue web substantially free from treated fiber.
14. The method of claim 1 wherein the first fiber is a hardwood fiber.
15. The method of claim 1 wherein the web is a multi-layered web having a first outer layer, a second outer layer and a middle layer disposed there between and the treated fiber is selectively disposed in the middle layer.
16. The method of claim 15 wherein the first fiber is a hardwood fiber and the middle layer comprises from about 10 to about 30 percent, by weight of the web, treated fiber.