Tissue products having substantially equal machine direction and cross-machine direction mechanical properties

a technology of machine direction and mechanical properties, applied in the field of tissue products, can solve the problems of product failure, strength alone ignore, etc., and achieve the effects of good stretch, improved in-use strength, and good stretch

Inactive Publication Date: 2005-06-23
KIMBERLY-CLARK WORLDWIDE INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0002] It has now been discovered that the perceived in-use strength of a tissue product can be improved by providing the product with one or more tissue sheets (plies) having substantially equal MD and CD tensile energy absorbed (TEA) (hereinafter defined) and a significant level of stretch, particularly in the CD direction of the sheet. The substantially equal TEA in combination with good stretch correlates with improved poke-through resistance for the tissue product, which is particularly important for bath tissue, but can be equally beneficial for facial tissue and towels.
[0003] Hence, in one aspect the invention resides in a tissue sheet having a three-dimensional surface topography, an MD / CD TEA ratio of from about 0.8 to about 1.2, more specifically from about 0.9 to about 1.1, still more specifically about 1.0, and a CD stretch of about 5 percent or greater. For purposes herein, a “three-dimensional surface topography” is a surface having regularly repeating elevated and relatively depressed regions having an average z-directional elevation difference of about 0.5 millimeter or greater, more specifically about 0.6 millimeter or greater, more specifically about 0.7 millimeter or greater, still more specifically about 1.0 millimeter or greater. The three-dimensional surface topography serves to provide the tissue sheet with the necessary level of stretch and / or CD strength.

Problems solved by technology

However, using a single strength value to characterize a sheet can be misleading because the MD and CD tensile strength values are typically very different, with the MD tensile strength being much greater than the CD tensile strength.
In use, the product is more likely to fail because its strength is limited by the weakest link, namely the CD tensile strength.
However, focusing on tensile strength alone ignores the key role that other properties play in the consumer's perception of strength.

Method used

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  • Tissue products having substantially equal machine direction and cross-machine direction mechanical properties
  • Tissue products having substantially equal machine direction and cross-machine direction mechanical properties
  • Tissue products having substantially equal machine direction and cross-machine direction mechanical properties

Examples

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example 1

Hypothetical

[0047] The need for significant stretch (about 5 percent or greater) is an important factor for purposes of this invention because it is relatively easy to remove stretch and lower tensile strength in the MD to make those properties equal to the stretch and tensile strength in the CD, thereby resulting in an equal or substantially equal MD TEA and CD TEA. However, since stretch and strength are much more difficult to generate in the CD, merely making these properties equal would only provide a weak sheet with low stretch with little or no consumer benefit. To illustrate this point, hypothetical products are listed in Table 1 below showing the effect of their properties on TEA.

TABLE 1MDCDMDTensileTensileStretchCDMD TEACD TEAProductg / 3″g / 3″%Stretch %g-cm / cm2g-cm / cm2A10008001559.82.6B800800552.62.6C80080010105.25.2

[0048] The hypothetical examples are assumed to have a linear stress-strain curve which is not usually the case for tissue products, which have stress-strain c...

examples 2-42

[0050] To further illustrate the invention, a pilot uncreped throughdried tissue machine was configured similarly to that illustrated in the aforementioned Rugowski et al. patent and was used to produce a one-ply, uncreped throughdried bath tissue basesheet. More specifically, 100 pounds of bleached northern softwood kraft fiber were dispersed in a pulper for 30 minutes at a consistency of 3 percent. Similarly, 100 pounds of bleached eucalyptus were dispersed in a pulper for 30 minutes at a consistency of 3 percent. The thick stock was then sent to a machine chest and diluted to a consistency of about 1 percent.

[0051] The machine chest furnish was diluted to approximately 0.1% consistency and delivered to a forming fabric using a three-layered headbox. The forming fabric speed was approximately 62 fpm. The resulting web was then transferred to a transfer fabric traveling at the same or slower than the forming fabric using a vacuum shoe to assist the transfer. At a second vacuum sho...

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Abstract

A tissue product having a combination of substantially equal tensile energy absorbed (TEA) in the machine direction and the cross-machine direction of the tissue sheet and a significant level of stretch in both directions provides improved perception of strength and resistance to “poke through” in use.

Description

BACKGROUND OF THE INVENTION [0001] In the field of tissue products, such as facial tissue, bath tissue, table napkins, paper towels and the like, the tensile strength of these sheet products is often measured as the geometric mean tensile strength, which takes into account the machine direction (MD) tensile strength and the cross-machine direction (CD) tensile strength. The geometric mean tensile strength is calculated as the square root of the product of the MD and CD tensile strengths. However, using a single strength value to characterize a sheet can be misleading because the MD and CD tensile strength values are typically very different, with the MD tensile strength being much greater than the CD tensile strength. In use, the product is more likely to fail because its strength is limited by the weakest link, namely the CD tensile strength. In response, some prior emphasis has been made on making products in which the machine direction (MD) and cross direction (CD) tensile streng...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): D21F11/00D21F11/14D21H27/00
CPCD21F11/006D21H27/00D21F11/145D21F11/14
Inventor HADA, FRANK STEPHENBAKKEN, ANDREW PETERHERMANS, MICHAEL ALANMATHEWS, JEFFREY DAVID
Owner KIMBERLY-CLARK WORLDWIDE INC
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