Tissue Web Rush Transfer for High CD Stretch and Tensile Strength
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Solution Overview
Problem
Conventional methods for increasing cross machine direction (CD) stretch in tissue products often compromise tensile strength, and there is a need for tissue basesheets with higher CD stretch and tensile strength while maintaining other important sheet properties.
Innovation Solution
A papermaking process involving two distinct rush transfers: the first from the forming fabric to the transfer fabric and the second from the transfer fabric to the through-air drying (TAD) fabric, with speed differentials between these fabrics to achieve enhanced CD stretch and tensile strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If conventional methods (creping, foreshortening) are used to increase CD stretch, then CD stretch is improved, but tensile strength deteriorates
Solution Approach 1:
The patent divides the single rush transfer process into two distinct rush transfers: first from forming fabric to transfer fabric, then from transfer fabric to TAD fabric. This segmentation allows independent optimization of stretch and strength parameters at each transfer stage, resolving the contradiction between achieving high CD stretch while maintaining tensile strength
Solution Approach 2:
The patent changes the process parameters by introducing a second rush transfer with specific speed differentials (10-50% overall differential between forming and TAD fabrics). This parameter change enables achieving CD stretch greater than 15% while maintaining CD tensile strength greater than 750 grams per 3 inches, simultaneously improving both contradictory parameters
2Strength
If refining or strengthening agents are used to increase MD and CD tensile, then tensile strength is improved, but softness deteriorates
Solution Approach 1:
The patent replaces chemical/refining methods with a mechanical process solution - the two-rush-transfer system. By using controlled speed differentials during fabric transfers, the process achieves high tensile strength through mechanical stretching and fiber alignment rather than chemical refinement, thereby maintaining web softness while achieving CD tensile greater than 750 grams per 3 inches
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The process results in tissue sheets with CD stretch greater than 15% and CD tensile strength greater than 750 grams per 3 inches, improving hand feel and reducing machine direction tears, while maintaining roll bulk and Kershaw firmness.
Implementation Method 1
the term 'rush transfer' generally refers to the process of subjecting the nascent web to differing speeds as it is transferred from one fabric in the papermaking process to another
Implementation Method 2
the second occurring when the web is transferred from the transfer fabric to the through-air drying fabric (TAD) fabric
Implementation Method 3
through-air drying (TAD) fabric
Data Source
AI summary
The present invention provides tissue products having increased CD stretch, which may be manufactured using a process in which the nascent web is subjected to two distinct rush transfers. The first rush transfer occurs when the web is transferred from the forming fabric to the transfer fabric, i.e., the “first position,” and the second occurs when the web is transferred from the transfer fabric to the through-air drying fabric (TAD) fabric, i.e., the “second position.” The overall speed differential between the forming fabric and the TAD fabric may be, for example, from about 10 to about 50 percent, with the amount of rush transfer being divided between the first and second position in a manner sufficient to achieve the desired CD stretch and other sheet properties.