Process for manufacturing multi-layer substrates comprising sandwich layers and polyethylene
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Solution Overview
Problem
Current methods for manufacturing cleaning wipes are inefficient, requiring loose pulp fibers, process water, drying steps, and chemical binders, and do not effectively utilize synthetic fibers in multi-layer substrates without delamination.
Innovation Solution
A method involving a multi-layer substrate with top and bottom pulp fiber layers and a thermoplastic material with specific tan delta characteristics, bonded through calendaring without chemical adhesives, allowing for fluid pathways and efficient loading of cleaning compositions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If chemical binders and process water are used to manufacture multi-layer wipes, then bonding between layers is achieved, but manufacturing complexity and capital investment increase
Solution Approach 1:
The patent removes chemical binders and process water from the manufacturing system, replacing them with a thermal bonding process that uses heat and pressure to fuse thermoplastic fibers directly to pulp layers, thereby simplifying the manufacturing process while maintaining layer bonding
Solution Approach 2:
The patent replaces chemical bonding mechanisms with thermal-mechanical bonding, using controlled heat and pressure application during calendaring to achieve layer fusion without chemical adhesives or binders
2Productivity
If high-speed manufacturing is implemented, then productivity increases, but manufacturing precision and bonding quality may deteriorate
Solution Approach 1:
The patent optimizes thermal and mechanical parameters (temperature, pressure, dwell time) during calendaring to achieve rapid bonding at high speeds while maintaining quality, using controlled parameter profiles that enable fast processing without sacrificing bonding integrity
Solution Approach 2:
The patent incorporates bonding action during the calendaring process itself, combining layer formation and thermal bonding in a single integrated step rather than separate operations, which enables high-speed manufacturing without compromising bonding quality
3Object-generated harmful factors
If thermoplastic material is used in the middle layer, then fluid pathways are created, but layer delamination may occur
Solution Approach 1:
The patent creates localized fluid pathways within the thermoplastic middle layer through controlled void formation, maintaining bonding strength in bonded regions while providing fluid channels in specific areas, thus achieving both fluid transport and delamination resistance
Solution Approach 2:
The patent uses a composite structure with thermoplastic fibers bonded to pulp layers, creating a multi-phase material system that combines the bonding advantages of thermoplastics with the fluid absorption and pathway capabilities of the pulp-thermoplastic interface
4Productivity
If synthetic fibers are used in the middle layer, then manufacturing efficiency improves, but fiber protrusion through surface layers occurs
Solution Approach 1:
The patent uses a continuous thermoplastic film or fiber mat in the middle layer that acts as a flexible barrier, containing synthetic fibers within the layer structure and preventing their protrusion through the surface pulp layers while maintaining manufacturing efficiency
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
Enables high-speed, low-capital-investment production of pre-moistened wipes with improved bonding and fluid communication between layers, reducing delamination and abrasiveness while maintaining effectiveness in cleaning and disinfection.
Implementation Method 1
heating the thermoplastic material to a temperature at which the thermoplastic material heat softens. During such heating there may also be application of pressure to the sandwich structure. In any case, such heating results in bonding of the thermoplastic material to groups of fiber in the top and bottom surface layers
Implementation Method 2
heating the thermoplastic material to a temperature at which the thermoplastic material heat softens
Data Source
AI summary
Methods for forming multi-layer substrates including top and bottom surface layers and a melt softened thermoplastic material layer between the exterior surface layers, where the thermoplastic material includes polyethylene or has a tan delta value of 0.2 to 0.4 within the temperature range of 100° F.-350° F. The 3 (or more) layers are assembled, and heated, melt softening the thermoplastic material, causing bonding of the thermoplastic layer to the exterior surface layers. A cleaning composition may be loaded onto the multi-layer substrate, where a fluid pathway through the melted thermoplastic material allows the cleaning composition to travel between the surface layers. Adhesion between the surface layers and the thermoplastic layer is provided by the thermoplastic material itself, which bonds to groups of fibers in the surface layers. The process does not require chemical adhesives, any processing water, drying, or the like, so as to be possible with low capital investment.