Tissue Rush Transfer Speed Differential Strength Softness
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Solution Overview
Problem
Conventional tissue products struggle to achieve high geometric mean tensile strength while maintaining low machine direction (MD) slope, which is essential for durability and softness, as existing methods often result in reduced MD stretch and increased modulus, leading to stiffness and tearing issues.
Innovation Solution
The process involves subjecting the embryonic web to a high degree of rush transfer, with a speed differential of 30 to 70% between forming and transfer fabrics, to increase MD stretch and decrease MD slope, thereby enhancing the tissue sheet's durability and softness without compromising tensile strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional methods are used to increase geometric mean tensile strength, then tensile strength is improved, but MD slope increases leading to increased stiffness
Solution Approach 1:
The invention changes the speed parameter of the transfer fabric relative to the forming fabric, creating a speed differential that induces rush transfer. This parameter change transforms the web structure during transfer, achieving low MD slope (reduced stiffness) while maintaining high geometric mean tensile strength, resolving the contradiction between strength and softness
2Ease of operation
If MD stretch is increased to reduce stiffness, then softness is improved, but tensile strength decreases
Solution Approach 1:
By changing the speed differential parameter between fabrics during rush transfer, the invention achieves a unique web configuration that simultaneously provides high MD stretch (improved softness) and high tensile strength, breaking the traditional trade-off between these properties
3Ease of operation
If rush transfer speed differential is increased to improve MD stretch, then softness increases, but manufacturing complexity increases
Solution Approach 1:
The invention adjusts the speed differential parameter within a specific range (30-70%) to achieve optimal softness and stretch properties. This parameter optimization ensures improved hand feel without excessive manufacturing complexity, as the process uses standard papermaking equipment operating at adjusted speeds
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
This approach results in tissue products with improved MD stretch, reduced MD slope, and increased geometric mean tensile strength, leading to enhanced hand feel, reduced tearing, and lower stiffness, while maintaining high tensile strength, thus addressing the limitations of conventional methods.
Implementation Method 1
The term 'rush transfer' generally refers to the process of subjecting the embryonic web to differing speeds as it is transferred from one fabric in the papermaking process to another
Data Source
AI summary
The present invention provides tissue products having a high degree of stretch and low modulus at relatively high tensile strengths, such as geometric mean tensile strengths greater than about 1500 g/3″ and more preferably greater than about 2000 g/3″. The combination of a tough, yet relatively supple sheet is preferably achieved by subjecting the embryonic web to a speed differential as it is passed from one fabric in the papermaking process to another, commonly referred to as rush transfer.