Web Material Structuring Belt Gradient Interlayer
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Solution Overview
Problem
Existing web material structuring belts, particularly laminated papermaking belts, face issues with lamination strength, air permeability, and fiber realignment, leading to imperfections and reduced durability in structured fibrous structures, such as sanitary tissue products.
Innovation Solution
The introduction of a web material structuring belt comprising a support layer, a structuring layer, and an associating layer, where the associating layer extends into both the support and structuring layers, enhancing lamination properties, air permeability, and fiber realignment, while maintaining void volumes between layers to improve delamination resistance and operational efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the structuring layer is laminated to the support layer at the interface between layers, then lamination strength is improved, but fibers are pulled into the support layer creating imperfections
Solution Approach 1:
The patent introduces an associating layer as an intermediary between the support layer and structuring layer. This associating layer has a gradient structure where it gradually transitions from the support layer into the structuring layer, avoiding direct lamination at the interface. The associating layer mediates the connection between layers, preventing fibers from being pulled into the support layer while maintaining strong lamination.
Solution Approach 2:
The patent transitions from a two-dimensional lamination interface to a three-dimensional gradient structure. The associating layer extends in the z-direction (through the thickness) creating a gradual transition zone rather than a sharp interface. This dimensional change allows fibers to transition smoothly between layers without being abruptly pulled into the support layer.
2Manufacturing precision
If the structuring layer is made thicker to improve structuring capability, then fiber realignment is enhanced, but air permeability decreases
Solution Approach 1:
The patent applies different properties to different regions of the structuring layer. The associating layer has a gradient structure where the composition and density vary locally - being more open and porous near the support layer interface and gradually transitioning to the denser structuring region. This local quality variation maintains air permeability in the lower region while providing sufficient structuring capability in the upper region.
Solution Approach 2:
The associating layer is designed with a porous gradient structure that maintains air permeability while providing the necessary structuring function. The porous nature of the associating layer, particularly in its transition zone, allows air to pass through while still enabling fiber realignment through the gradient structure.
3Device complexity
If the structuring layer is laminated directly to the support layer, then device complexity is reduced, but delamination occurs under process conditions
Solution Approach 1:
The associating layer serves as a mediator that enhances the reliability of the lamination under process conditions. By introducing this intermediate layer with gradient properties, the patent prevents direct contact between the support layer and structuring layer, eliminating the delamination issues that occur with direct lamination while maintaining reasonable structural simplicity.
Solution Approach 2:
The patent creates a composite belt structure consisting of three distinct layers: support layer, associating layer, and structuring layer. This composite structure combines the strengths of each layer - the support layer provides mechanical strength, the associating layer provides gradient transition and adhesion, and the structuring layer provides fiber realignment capability. The composite nature improves overall reliability under process conditions.
4Productivity
If processing speed is increased to improve productivity, then output is enhanced, but drying efficiency decreases
Solution Approach 1:
The gradient porous structure of the associating layer, particularly its higher porosity in the transition zone, enables rapid moisture removal during high-speed processing. The porous network provides efficient capillary action and surface area for evaporation, maintaining drying efficiency even at increased processing speeds where residence time is reduced.
Data Source
AI summary
Web material structuring belts that impart structure to a web material during a web material structuring operation and/or structured web material forming operation, method for making same and methods for using same to make structured web materials, for example structured fibrous structures, such as structured sanitary tissue products such as structured toilet tissue, structured paper towels and structured facial tissue are provided.