Multilayer Polyethylene Film for Recyclable Low-Temperature Packaging
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Solution Overview
Problem
Existing polyethylene films used in packaging materials face challenges in recyclability, mechanical and thermal properties, especially at low temperatures, leading to environmental pollution and damage during processing and use, with issues like cracks, tears, and poor heat-sealing properties.
Innovation Solution
A polyethylene film with a multi-layer structure comprising specific ethylene polymers with varying densities and properties, including an outer, intermediate, and inner layer, designed to balance falling ball impact strength and puncture strength, ensuring excellent durability and heat-sealing properties even at low temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a polyolefin resin film is used as a single-material packaging material to enable recyclability, then environmental friendliness and recyclability are improved, but mechanical properties and thermal properties deteriorate, leading to poor durability at low temperatures and defective heat-sealing
Solution Approach 1:
The packaging material is divided into multiple layers with different polyolefin resins having distinct melting points. The first layer has a lower melting point for easy heat-sealing, while the second layer has a higher melting point for durability at low temperatures. This segmentation allows each layer to fulfill its specific function, resolving the contradiction between recyclability and low-temperature durability.
Solution Approach 2:
Different regions of the packaging material have different properties tailored to their specific functions. The first layer is optimized for heat-sealing operations, while the second layer is optimized for mechanical strength and low-temperature resistance. This local differentiation of material properties enables the overall system to achieve both recyclability and reliability.
2Reliability
If polyolefin resins with different densities and compositions are laminated to improve mechanical and thermal properties, then durability is improved, but the complexity of the structure increases and commercialization becomes difficult
Solution Approach 1:
The invention varies the melting point parameter of the polyolefin resins between layers to achieve different functional properties. By controlling the melting point difference between the first and second layers, the patent achieves both ease of heat-sealing and low-temperature durability without requiring complex additives or compositions, thus managing structural complexity while improving reliability.
3Use of energy by moving object
If the film is used at low temperatures, then energy saving and environmental benefits are improved, but the film becomes vulnerable to cracks, tears, and impact damage
Solution Approach 1:
The film structure is segmented into two layers with different thermal properties. The second layer, having a higher melting point, maintains its mechanical strength and impact resistance at low temperatures, while the first layer with lower melting point facilitates energy-efficient heat-sealing. This segmentation resolves the contradiction between energy saving and impact resistance.
Data Source
AI summary
Provided is a polyethylene film having a multi-layer structure including an outer layer (A) including a first ethylene polymer having a density M1 of 0.935≤M1≤0.968; an intermediate layer (B) including a second ethylene polymer having a density M2 of 0.900≤M2≤0.920; and an inner layer (C) including a third ethylene polymer having a density M3 of 0.850≤M3≤0.905, wherein the outer layer (A), the intermediate layer (B), and the inner layer (C) are sequentially laminated to form the polyethylene film comprising the multi-layer structure, and wherein a falling ball impact strength per unit thickness and a puncture strength per unit thickness of the polyethylene film comprising the multi-layer structure are 3.0 to 15.0 g/μm and 0.2 to 0.4 N/μm, respectively, and a difference in melting point between the outer layer (A) and the inner layer (C) is 30 to 100° C.