Method to debond paper on a paper machine

Abstract

Disclosed is a method of making a soft, strong cellulosic tissue sheet comprising the steps of forming a web of cellulosic fibers on a forming wire, thereafter treating the exposed surface of the web with a treatment composition comprising a chemical debonding agent, subjecting the opposing surface of the web to vacuum suction whereby the chemical debonding agent is distributed substantially through the entire thickness of the web, and through-air drying the web. The method allows grade changes to be made much more rapidly and with less waste than when adding debonder at the wet end of the paper making process.

Description

BACKGROUND OF THE INVENTION [0001] In the manufacture of paper products from cellulose fibers, such as facial tissue, bath tissue, paper towels, dinner napkins and the like, it is often desirable to enhance product properties by the addition of chemical additives. Properties that may be enhanced using additives include: dry strength, wet strength, softness, absorbency, opacity, brightness and color. [0002] Softness is a key attribute in tissue products. A feeling of softness imparts to human skin a clean and soothing effect. Improving the balance of tissue softness and strength is a continuous effort in tissue making. Tissue product designers attempt to maximize the strength and softness of tissues. It has been recognized as a general rule of tissue manufacture that the greater the strength of a given tissue, the lower the softness of that tissue. There is usually an inverse relationship between strength and softness. [0003] In general, prior efforts have been directed at achieving ...

AI Technical Summary

Benefits of technology

[0007] Desirably, the treatment composition may be applied to the web when the web has a consistency of greater than about 10%. More desirably, the treatment composition may be applied to the web when the web has a consistency of greater than about 15% and less than about 80%. Even more desirably, the treatment composition may be applied to the web when the web has a consistency of greater than about 15% and less than about 30%.

[0008] The treatment composition may include any of those chemical debonding agents known to one skilled in the art. In one embodiment, the chemical debonding agent comprises a quaternary amine compound, for example, an oleyl imidazolinium compound. In the dried product, the chemical debonding agent may be present in the product in an amount of from about 0.01% to about 10% by weight. In another embodiment, the chemical debonding agent may be present in an amount effective to soften substantially the entire thickness of the sheet.

Problems solved by technology

Through-air drying processes, however, are not as amenable to creping as Yankee dryer processes.

However, adding debonder to the fiber furnish results in debonder being present in the whitewater that is recirculated after formation of the paper web.

As there is often a large quantity of white water, the presence of additives in the whitewater can result in significant down time for grade changes, or large amounts of waste material produced when changing chemical compositions.

However, such chemical addition methods result in higher concentrations of chemical at the surface of the paper sheet, with lower concentrations in the middle of the sheet.

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