Asymmetric Crosslinked Polyethylene Film for Recyclable Heat-Sealed Packaging
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Solution Overview
Problem
Polyethylene films used in packaging are inadequate in heat resistance and strength, and laminates made of different resin films are difficult to recycle due to separation issues.
Innovation Solution
A single-layer polyethylene film is created with differing crosslink densities on each side by irradiating one side with an electron beam, incorporating a crosslinking agent and light stabilizer, and a laminate is formed with one side irradiated and the other not, maintaining heat sealability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a lamination film made of different resin films is used, then heat resistance and strength are improved, but recyclability deteriorates due to difficulty in separation
Solution Approach 1:
The invention segments the polyethylene film into two regions with different crosslink densities: a radiation-irradiated region with high crosslink density for heat resistance, and a non-irradiated region with low crosslink density for sealability and recyclability. This internal segmentation allows a single film to perform multiple functions that previously required separate resin layers.
Solution Approach 2:
The invention applies local quality by creating spatially varying crosslink density within the polyethylene film. The irradiated side has high crosslink density (improving heat resistance), while the non-irradiated side has low crosslink density (maintaining sealability). This local differentiation eliminates the need for multi-resin lamination while preserving both heat resistance and recyclability.
2Strength
If a polyethylene film is irradiated with electron beam on both sides, then heat resistance and strength are improved, but heat sealability deteriorates
Solution Approach 1:
The invention segments the film structure into irradiated and non-irradiated regions, where only the irradiated region undergoes crosslinking to improve heat resistance, while the non-irradiated region remains suitable for heat sealing. This segmentation resolves the contradiction by applying crosslinking selectively rather than uniformly.
Solution Approach 2:
The invention implements local quality by creating asymmetric crosslink density distribution: high crosslink density on the irradiated side for heat resistance, and low crosslink density on the non-irradiated side for heat sealability. This local differentiation allows each region to optimize its properties for specific functions.
3Ease of manufacture
If conventional polyethylene film is used, then cost is reduced and simplicity is maintained, but heat resistance and strength are insufficient
Solution Approach 1:
The invention changes the physical-chemical parameters of polyethylene by introducing crosslinking through electron beam irradiation. This parameter change (crosslink density) transforms the material properties to achieve high heat resistance and strength while maintaining the simplicity of a single-polyethylene structure, avoiding the complexity of multi-resin lamination.
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 film achieves improved heat resistance and strength on one side while retaining sealability on the other, enabling recyclable packages without the need for laminates.
Implementation Method 1
irradiation of an electron beam to a polyethylene film can occur curing or crosslinking of polyethylene near the film surface irradiated with the electron beam
Implementation Method 2
irradiation of an electron beam to a polyethylene film can occur curing or crosslinking of polyethylene near the film surface irradiated with the electron beam
Data Source
AI summary
There is provided a polyethylene film and a laminate which can be used to produce a package having high heat resistance, strength and recycling suitability in place of a lamination film conventionally used in a package. The polyethylene film of the present invention is irradiated with an electron beam on its only one side, and comprises polyethylene and a crosslinking agent, in which the crosslink density of the polyethylene is different between the side irradiated with an electron beam and the other side not irradiated with an electron beam.