Tissue Rush Transfer Speed Differential MD Slope
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Solution Overview
Problem
Conventional tissue products face a challenge in achieving high geometric mean tensile strength while maintaining low machine direction (MD) slope, which affects durability and hand feel.
Innovation Solution
The process involves subjecting the embryonic web to a high degree of rush transfer when transferring from the forming fabric to the transfer fabric, with a speed differential of 30 to 70 percent, to increase MD stretch and reduce MD slope, thereby enhancing tissue product properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional tissue manufacturing methods are used, then geometric mean tensile strength can be increased, but machine direction slope increases and machine direction stretch decreases
Solution Approach 1:
The patent applies dynamic speed differential during the web transfer process. The forming fabric and transfer fabric operate at different speeds (30-70% differential), creating controlled rush transfer that dynamically stretches the web in the machine direction. This dynamic mechanical action during manufacturing imparts permanent stretch characteristics to the tissue product, resolving the contradiction between strength and stretchability.
Solution Approach 2:
The patent changes the operational parameters of the papermaking process by introducing a significant speed differential between fabrics. By adjusting the speed ratio parameter from conventional near-equal speeds to a 30-70% differential, the process transforms the web's mechanical properties during formation, achieving both high tensile strength and high machine direction stretch simultaneously.
2Strength
If conventional tissue manufacturing methods are used, then geometric mean tensile strength can be increased, but machine direction slope increases reducing hand feel quality
Solution Approach 1:
The dynamic rush transfer process creates controlled deformation and relaxation cycles in the web during manufacturing. The alternating tension and release during speed differential transfer impart a flexible microstructure that reduces slope while maintaining strength, improving hand feel quality.
Solution Approach 2:
By changing the speed differential parameter to 30-70%, the process fundamentally alters the web's structural development. This parameter change produces a more open, flexible fiber network that achieves low slope values alongside high tensile strength, resolving the strength-slope contradiction.
3Reliability
If high geometric mean tensile strength is achieved, then durability improves, but machine direction slope increases making the tissue stiffer
Solution Approach 1:
The dynamic rush transfer process creates a unique fiber arrangement through controlled motion variations. This dynamic manufacturing approach produces strong yet flexible bonding patterns that simultaneously improve durability and reduce stiffness, overcoming the traditional trade-off between these properties.
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 durability and improved hand feel without compromising tensile strength.
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. The present invention provides a process in which the embryonic web is subjected to a high degree of rush transfer when the web is transferred from the forming fabric to the transfer fabric
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.