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 for producing pre-moistened multi-layer cleaning wipes using a thermoplastic material with specific tan delta characteristics, sandwiched between pulp fiber layers, which softens and bonds without chemical adhesives, creating a fluid pathway for liquid distribution and maintaining structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If chemical binders are used to bond layers together, then bonding strength is improved, but product purity and safety deteriorate due to residual chemicals
Solution Approach 1:
The patent replaces chemical bonding systems with a thermal-mechanical bonding system. A thermoplastic layer is heated to its melting point, allowing it to flow and bond the pulp layers together through thermal fusion and mechanical interlocking, eliminating the need for chemical adhesives and their associated harmful residues
Solution Approach 2:
The patent utilizes the phase transition of the thermoplastic material from solid to liquid state upon heating. This phase change enables the thermoplastic layer to become viscous and flow, facilitating bonding between layers through thermal fusion, then solidifies upon cooling to provide structural integrity without chemical binders
2Stability of the object's composition
If loose pulp fibers are used in the manufacturing process, then fiber distribution is improved, but process complexity and capital investment increase due to additional equipment for fiber handling
Solution Approach 1:
The patent applies preliminary action by pre-forming the pulp layers into stable mat structures before the bonding process. These pre-formed mats maintain their fiber distribution and structural integrity throughout handling, eliminating the need for complex loose fiber handling equipment while achieving uniform composition in the final product
Solution Approach 2:
The patent creates a composite structure where pre-formed pulp mats are combined with a thermoplastic bonding layer. This composite approach allows the pulp layers to maintain their fiber distribution stability while the thermoplastic layer provides the bonding function, simplifying the overall manufacturing process
3Ease of operation
If process water is used to maneuver fibers, then fiber manipulation is improved, but manufacturing time increases due to required drying steps
Solution Approach 1:
The patent replaces water-based fiber manipulation with a dry thermal-mechanical process. The pre-formed pulp mats are handled in their dry state, and bonding is achieved through heat and pressure application rather than wet processing, completely eliminating the drying step and associated time losses
Solution Approach 2:
The patent changes the processing parameters from wet to dry conditions. By maintaining the pulp layers in a dry state throughout handling and using thermal energy instead of water for bonding, the process eliminates the time-consuming drying step while improving manufacturing efficiency
4Strength
If a liquid impervious thermoplastic layer is used, then layer bonding is improved, but fluid communication between layers deteriorates
Solution Approach 1:
The patent applies local quality by creating selective permeability in the thermoplastic layer. The bonding interfaces remain intact to provide structural strength, while controlled openings or channels are introduced at specific locations to allow fluid communication between layers, achieving both bonding and fluid pathway requirements
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 wipes with improved bonding and fluid communication between layers, reducing delamination and abrasiveness, while maintaining pulp fiber dominance and synthetic fiber utility.
Implementation Method 1
heating the thermoplastic material to a temperature at which the thermoplastic material heat softens
Implementation Method 2
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 3
After heat softening, the thermoplastic material includes pores therethrough, providing a fluid pathway therethrough such that any liquid loaded into the top surface layer is able to pass through the pathway, into the bottom surface layer
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.