Uncreped tissue sheets having a high wet:dry tensile strength ratio
First Claim
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1. A method of treating a papermaking pulp useful for making a paper sheet, the method comprising;
- (a) adding a quaternary debonder to the pulp in an amount sufficient to significantly reduce the dry cross-machine direction (CD) tensile strength of the sheet;
(b) thereafter adding a wet strength agent to the same pulp in an amount sufficient to provide the sheet with a ratio of the wet CD tensile strength to the dry CD tensile strength (Wet/Dry Ratio) of 0.50 or greater; and
(c) thereafter adding a dry strength agent to the same pulp in an amount sufficient to increase the dry CD tensile strength of the sheet.
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Abstract
The ratio of the wet tensile strength to the dry tensile strength of uncreped throughdried tissues and towels can be increased by treating the papermaking pulp with a debonder, a wet strength agent and a dry strength agent. The properties of the resulting product can be manipulated to either provide a product with normal degree of softness (as measured by the machine direction sheet stiffness) and a high wet strength, or a normal degree of wet strength and a higher degree of softness.
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Citations
42 Claims
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1. A method of treating a papermaking pulp useful for making a paper sheet, the method comprising;
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(a) adding a quaternary debonder to the pulp in an amount sufficient to significantly reduce the dry cross-machine direction (CD) tensile strength of the sheet;
(b) thereafter adding a wet strength agent to the same pulp in an amount sufficient to provide the sheet with a ratio of the wet CD tensile strength to the dry CD tensile strength (Wet/Dry Ratio) of 0.50 or greater; and
(c) thereafter adding a dry strength agent to the same pulp in an amount sufficient to increase the dry CD tensile strength of the sheet. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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- 14. An uncreped paper sheet comprising from about 5 to about 30 pounds of a quaternary amine debonder per metric ton of dry fiber, from about 5 to about 30 pounds of a polyamide-epichlorohydrin wet strength resin per metric ton of dry fiber and from about 5 to about 30 pounds of a dry strength agent per metric ton of dry fiber, said paper sheet having Wet/Dry Ratio of 0.50 or greater and a machine direction stiffness of about 30 kilograms or less per 3 inches of width.
- 19. An uncreped paper sheet comprising from about 5 to about 30 pounds of a quaternary ammonium debonder per metric ton of dry fiber, from about 5 to about 30 pounds of a polyamide-epichlorohydrin wet strength resin per metric ton of dry fiber and from about 5 to about 30 pounds of a dry strength agent per metric ton of dry fiber, wherein the ratio of the Wet/Dry Ratio to the machine direction stiffness is about 0.015 or greater.
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22. A method of treating a softwood papermaking pulp useful for making a paper sheet the method comprising:
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(a) adding a quaternary debonder to the softwood pulp in an amount sufficient to significantly reduce the dry cross-machine direction (CD) tensile strength of the sheet;
(b) thereafter adding a wet strength agent to the softwood pulp in an amount sufficient to provide the sheet with a ratio of the wet CD tensile strength to the dry CD tensile strength (Wet/Dry Ratio) of 0.50 or greater; and
(c) thereafter adding a dry strength agent to the softwood pulp in an amount sufficient to increase the dry CD tensile strength of the sheet. - View Dependent Claims (23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34)
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- 35. A single-ply uncreped paper sheet consisting essentially of softwood fibers, said sheet comprising from about 5 to about 30 pounds of a quaternary amine debonder per metric ton of dry fiber, from about 5 to about 30 pounds of a polyamide-epichlorohydrin wet strength resin per metric ton of dry fiber and from about 5 to about 30 pounds of a dry strength agent per metric ton of dry fiber, said paper sheet having Wet/Dry Ratio of 0.50 or greater and a machine direction stiffness of about 30 kilograms or less per 3 inches of width.
- 40. A single-ply uncreped paper sheet consisting essentially of softwood fibers, said sheet comprising from about 5 to about 30 pounds of a quaternary ammonium debonder per metric ton of dry fiber, from about 5 to about 30 pounds of a polyamide-epichlorohydrin wet strength resin per metric ton of dry fiber and from about 5 to about 30 pounds of a dry strength agent per metric ton of dry fiber, wherein the ratio of the Wet/Dry Ratio to the machine direction stiffness is about 0.015 or greater.
Specification