Tissue Web Rush Transfer for High CD Stretch and Strength
Find Innovative SolutionsGenerate Solutions
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 rush transfer process is divided into two distinct positions: first position (forming fabric to transfer fabric) and second position (transfer fabric to TAD fabric). This segmentation allows independent optimization of stretch and strength at each transfer stage, resolving the contradiction between CD stretch and tensile strength that plagues conventional single-position methods.
Solution Approach 2:
The invention changes the operational parameters by introducing speed differentials between fabrics at two distinct positions. The first rush transfer uses a speed differential of about 5-15% and the second uses about 10-20%, creating cumulative CD stretch (15-35%) while maintaining tensile strength through controlled deformation at each stage rather than single-stage aggressive stretching.
2Strength
If refining or strengthening agents are used to increase tensile strength, then tensile strength is improved, but softness deteriorates
Solution Approach 1:
The invention enables the web to achieve high tensile strength through self-service mechanical means (controlled rush transfers) rather than relying on chemical refining or strengthening agents. The two-position rush transfer process creates internal fiber bonding and orientation that provides strength without compromising the inherent softness of the tissue web.
3Device complexity
If single rush transfer is used, then process complexity is reduced, but CD stretch is insufficient
Solution Approach 1:
The invention adds a temporal dimension to the rush transfer process by implementing it at two distinct positions in the papermaking sequence rather than single position. This dimensional expansion (from one to two transfer stages) enables cumulative stretch effects while maintaining relatively simple fabric and process architecture, achieving high CD stretch without excessive complexity.
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 tearing, while maintaining other essential sheet properties.
Implementation Method 1
the nascent web is subjected to two distinct rush transfers. 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 nascent web is subjected to two distinct rush transfers, the first occurring when the web is transferred from the forming fabric to the transfer fabric, i.e., the 'first position,' and 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 fabric (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.