Polyethylene Laminate with Thermosetting Protective Layer
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Solution Overview
Problem
Conventional laminates used in packaging bags face issues with heat-sealing properties, recyclability, and environmental impact due to the combination of multiple materials, leading to energy consumption in separation and sorting, and insufficient strength for packaging liquids.
Innovation Solution
A laminate configuration with a protective layer, substrate layer, and sealant layer, where the substrate and sealant layers are made of polyethylene, and a thermosetting resin is used as a protective layer with a melting point of 160°C or higher, ensuring high recyclability and improved heat-sealing properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple materials are combined in laminate packaging to provide different functions (mechanical strength, heat-sealing, barrier properties), then the functional performance is improved, but the recyclability deteriorates because material separation and sorting require energy-consuming thermal, chemical, and mechanical actions
Solution Approach 1:
The laminate is segmented into distinct layers with specific functions: a polyethylene substrate layer for mechanical strength, a polyethylene sealant layer for heat-sealing, and a thermosetting resin protective layer for barrier properties. This segmentation allows each layer to perform its function while maintaining overall recyclability through the dominant polyethylene content (90 mass% or greater).
Solution Approach 2:
The invention changes the material composition parameter by ensuring polyethylene constitutes 90 mass% or greater of the total laminate. This parameter change enables the packaging to meet recyclability standards while still incorporating functional layers for heat-sealing and barrier properties, thereby reducing energy consumption during recycling compared to conventional multi-material laminates.
2Reliability
If conventional multilayer films with various materials are used to achieve heat-sealing and gas barrier properties, then the functional properties are improved, but the ease of recycling deteriorates because the materials cannot be easily separated and sorted after use
Solution Approach 1:
The invention merges the substrate and sealant layers into the same polyethylene material, eliminating the need for separate material types in these critical functional layers. This merging simplifies recycling while maintaining heat-sealing capability through the polyethylene sealant layer and structural integrity through the polyethylene substrate layer.
Solution Approach 2:
The polyethylene material serves multiple functions simultaneously: providing mechanical strength as the substrate layer, enabling heat-sealing as the sealant layer, and contributing to overall recyclability. This multi-functionality reduces the need for specialized materials that would complicate recycling processes.
3Productivity
If the substrate layer is made of polyethylene to improve recyclability, then the recyclability is improved, but the heat resistance deteriorates because polyethylene has a low melting point and may adhere to heat-sealing jigs or cause wrinkling
Solution Approach 1:
The invention introduces a thermosetting resin protective layer as an intermediary between the polyethylene substrate and the heat-sealing process. This protective layer has high heat resistance and prevents the polyethylene substrate from directly contacting hot heat-sealing jigs, thereby preventing adhesion and wrinkling while maintaining the recyclability benefits of polyethylene.
Solution Approach 2:
The laminate employs a composite structure combining polyethylene (for recyclability and mechanical properties) with thermosetting resin (for heat resistance). This composite material approach allows the package to achieve both high recyclability through polyethylene content of 90 mass% or greater and adequate heat resistance through the thermosetting protective layer.
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
The laminate achieves excellent recyclability, heat-sealing properties, and strength, reducing energy consumption and environmental impact while enabling the packaging of liquids with improved productivity.
Implementation Method 1
the protective layer contains a thermosetting resin or a resin having a melting point of 160° C. or higher
Implementation Method 2
a process of forming a packaging bag includes heat-sealing, in which a pressure is applied to the outer surface-side of the substrate layer of the laminate with a jig heated to high-temperatures
Implementation Method 3
polyethylene, polypropylene, ethylene vinyl acetate copolymer, or the like is also used as a heat-sealing material of the packaging bag to seal the contents
Data Source
AI summary
A laminate includes a protective layer; a substrate layer; and a sealant layer, laminated in this order, wherein the substrate layer and the sealant layer contain polyethylene, the protective layer contains a thermosetting resin or a resin having a melting point of 160° C. or higher, and a ratio of polyethylene in the laminate is 90 mass % or more.