Absorbent Laminate Structure for Low MD Stretch and High Strength
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Solution Overview
Problem
Existing absorbent structures, such as disposable paper towels and wipes, face challenges in achieving high strength, absorbency, and softness while minimizing machine direction (MD) stretch, which is typically achieved at the cost of increased energy consumption and production complexity.
Innovation Solution
The development of a laminate structure using a through air drying (TAD) process with a structuring fabric and embossed plies, where the absorbent product has a measured Y-Connected Area greater than 20 and Surface Channel Spacing of less than 2.5 mm, allowing for high ball burst strength, absorbency, and softness at low MD stretch levels, achieved through the use of cellulosic-based and synthetic fibers with a water-soluble adhesive and specific embossment patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If conventional wet crepe or dry crepe processes are used to produce absorbent structures, then production is easy and energy consumption is low, but the sheet pressing compacts the web which lowers web thickness and resulting absorbency
Solution Approach 1:
The patent removes the sheet pressing step from the conventional crepe process sequence. By extracting this compaction step, the web maintains its thickness and absorbency characteristics while still allowing the drying and creping operations to proceed, thus resolving the contradiction between energy efficiency and absorbency
Solution Approach 2:
The drying process is segmented into two distinct stages: through-air drying to achieve partial dryness, followed by Yankee dryer finishing. This segmentation allows the web to be dried without the compaction that would occur in conventional single-stage processes, maintaining both thickness and absorbency while controlling energy consumption
2Strength
If high MD stretch is achieved in absorbent structures, then strength is improved, but productivity decreases and production complexity increases
Solution Approach 1:
The patent changes the physical parameters of the web during processing, specifically controlling the moisture content at different stages (higher moisture during TAD, lower moisture during Yankee drying). This parameter control allows the web to develop strength characteristics without requiring high MD stretch, thus maintaining productivity while achieving adequate ball burst strength
Solution Approach 2:
Instead of relying solely on machine direction stretch for strength development, the patent utilizes the cross-directional structure created by the structured fabric and the vertical thickness maintenance from non-pressing drying. This dimensional approach provides strength through structural integrity rather than unidirectional stretching
3Use of energy by stationary object
If sheet pressing is used to remove moisture from the web, then energy consumption is reduced, but web thickness and absorbency are lowered
Solution Approach 1:
The sheet pressing operation is extracted from the process sequence entirely. Moisture removal is achieved through air drying and Yankee dryer evaporation instead of mechanical pressing, which maintains web thickness while still reducing moisture content to appropriate levels for the final product
Solution Approach 2:
The patent uses pneumatic methods (through-air drying with air flow) and hydraulic methods (Yankee dryer steam heating and evaporation) to remove moisture from the web. These non-mechanical pressing methods maintain web thickness while achieving the necessary moisture reduction, unlike conventional mechanical sheet pressing
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 absorbent products with enhanced ball burst strength, absorbency, and softness, while reducing the need for high MD stretch, thereby improving productivity and lowering costs by minimizing the use of raw materials and energy.
Implementation Method 1
The web is then dried and creped from the Yankee Dryer
Implementation Method 2
enhance the strength and absorbency of these towels and wipes, more than one layer of web (or ply) can be laminated together using strictly a mechanical process or preferably a mechanical process that utilizes an adhesive
Data Source
AI summary
Absorbent product including a laminate of at least two plies, wherein the absorbent product has a measured Y-Connected Area parameter greater than 20 and a Surface Channel Spacing of less than 2.5 mm. The absorbent product has high strength and low machine direction stretch.