Tissue products containing deliquescent materials and non-ionic surfactants

Abstract

Tissue products, such as facial tissue, bath tissue, paper towels, table napkins and the like can be improved by incorporating a sufficient amount of a deliquescent material and a non-ionic surfactant into the product. The deliquescent material is capable of maintaining a very high equilibrium amount of water in the product which can be advantageous in preventing the products from drying out and improving hand feel. The non-ionic surfactant improves the ability to incorporate the deliquescent materials into the tissue products quickly during manufacture and can help control the equilibrium moisture content of the product.

Description

BACKGROUND OF THE INVENTION [0001] Tissue products, such as facial tissue, toilet paper, table napkins, paper towels and the like, generally have a very low moisture content of about 5 percent or less. While it is known to add humectants to tissue products to absorb moisture and improve the hand feel, humectants do not absorb appreciable quantities of water relative to their weight. Hence, very large amounts of the humectant material are required to absorb moisture in amounts sufficient to be effective. In addition, humectant materials do not form solutions with the water but rather exist as water / humectant complexes. Hence the water is bound to the humectant material and does not impart the same effect as free water in the sheet. Further, if the humectant material is a solid particulate, it will remain as a solid particulate in the sheet and can impart a gritty feel. [0002] In commonly-assigned co-pending patent application Ser. No. 10 / 808,744, filed Mar. 24, 2004, by Shannon et al...

AI Technical Summary

Benefits of technology

[0004] It has now been discovered that aqueous solutions having a sufficiently high concentration of deliquescent salts, in particular deliquescent inorganic salts, can be incorporated into tissue product sheets at high speeds so as to impart a noticeable wet feel to the product. In particular, it has been determined that combining a non-ionic surfactant with the deliquescent salt solution reduces the surface tension of the solution sufficiently to enable the deliquescent salt solution to be quickly absorbed by the tissue sheet. Furthermore, it has been discovered that the non-ionic surfactant can be used to control the equilibrium moisture content of the sheet and thereby optimize the tactile sheet properties insuring that the sheet has sufficient moisture to provide a significant improvement in handfeel, yet does not give the appearance of a wet tissue sheet. In addition, certain non-ionic surfactants are capable of providing improved feel characteristics to the sheet by themselves, thus making the use of such materials particularly advantageous.

[0011] It is found that in the absence of the non-ionic surfactant, the concentration of the salt solution does have an impact on the ability of the sheet to rapidly absorb the salt solution. In particular, concentrated salt solutions are found to be much more slowly absorbed than dilute solutions. On the other hand, it will be readily apparent to those skilled in the tissue making art that being able to apply solutions having a high solids concentration to the web can be advantageous in that the need to transfer less material can allow higher machine speeds to be achieved, there are fewer issues with web handling and there is less of a need to dry / condition the product in order to obtain the desired moisture level in the final product. Accordingly, for purposes herein, the amount of the deliquescent salt in the surfactant / deliquescent salt solution can be from about 20 to about 80 dry weight percent, more specifically from about 25 to about 70 dry weight percent, and still more specifically from about 30 to about 70 dry weight percent.

[0019] An especially interesting class of polyether polysiloxanes are the amino-funcitonal polyether polysiloxanes. Exemplary aminofunctional polyether polysiloxanes are the Wetsoft CTW family manufactured and sold by Wacker, Inc. Other exemplary polysiloxanes can be found in U.S. Pat. No. 6,432,270 by Liu, et.al. These amino-functional polyethers are found to be capable of substantially increasing the surface feel of the product. Hence, use of such materials can simultaneously increase the transfer efficiency of the surfactant / deliquescent salt solution to the tissue sheet while further increasing the surface softness of the product.

Problems solved by technology

Furthermore, it has been discovered that the non-ionic surfactant can be used to control the equilibrium moisture content of the sheet and thereby optimize the tactile sheet properties insuring that the sheet has sufficient moisture to provide a significant improvement in handfeel, yet does not give the appearance of a wet tissue sheet.

Images