Multi-Layer Polyethylene Film for Recyclable Heat-Sealed Packaging
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Solution Overview
Problem
Existing polyolefin-based packaging materials face challenges in recyclability, mechanical and thermal property deterioration, and poor heat-sealing properties, especially at low temperatures, leading to environmental pollution and damage during processing and use.
Innovation Solution
A polyethylene film with a multi-layer structure comprising specific ethylene polymers with controlled densities and thickness ratios, ensuring balanced falling ball impact and puncture strengths, and a defined melting point difference, allowing for excellent heat-sealing and durability even at low temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a polyolefin-based single material is used to achieve recyclability, then environmental friendliness is improved, but mechanical properties and thermal properties are deteriorated
Solution Approach 1:
The polyolefin film is divided into multiple layers with different ethylene polymer densities (0.935≤M1≤0.968 for outer layer, 0.900≤M2≤0.920 for intermediate layer, 0.850≤M3≤0.905 for inner layer), allowing each layer to contribute different properties while maintaining overall recyclability
Solution Approach 2:
The patent creates a composite structure using multiple ethylene polymers with different densities and melting points in a single polyolefin film, achieving both recyclability and improved mechanical/thermal properties without using different material types
2Object-generated harmful factors
If polyolefin resin with inferior mechanical properties is used to maintain single-material structure, then recyclability is improved, but durability is deteriorated
Solution Approach 1:
The film structure is segmented into outer, intermediate, and inner layers with progressively lower density polymers, where the outer layer provides durability and the inner layer provides heat-sealing properties, all while remaining single-material polyolefin
Solution Approach 2:
Different regions of the film have different polymer densities and properties - the outer layer (M1) has higher density for durability and scratch resistance, while the inner layer (M3) has lower density for heat-sealing, creating local quality variations within the single-material structure
3Object-generated harmful factors
If polyolefin resin with inferior heat resistance is used to maintain single-material composition, then recyclability is improved, but heat-sealing properties are deteriorated
Solution Approach 1:
The film is segmented into layers with different melting points - the inner layer with lowest density (M3) has lowest melting point for easy heat-sealing, while outer layers have higher melting points for heat resistance, enabling heat-sealing at lower temperatures without damaging the structure
Solution Approach 2:
The inner layer is designed with specific properties (lowest density, lowest melting point) optimized for heat-sealing function, while outer layers have properties optimized for heat resistance and durability, creating functional differentiation within the single-material film
4Reliability
If a multi-layer structure with different polyolefin resins is used to improve mechanical and thermal properties, then property balance is improved, but cost and low-temperature durability are deteriorated
Solution Approach 1:
The patent optimizes specific parameter ranges for density (M1, M2, M3) and melting point differences to achieve the best balance of properties - for example, setting M1 between 0.935-0.968 and M3 between 0.850-0.905 to simultaneously achieve durability, heat-sealing properties, and cost-effectiveness
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.