Multilayer Film Core Layer Ethylene Copolymer Recyclability
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Solution Overview
Problem
Existing multilayer films used in industrial and consumer products face challenges in recyclability due to the use of incompatible materials, and they often lack sufficient tear resistance.
Innovation Solution
The development of multilayer films with a core layer comprising greater than 90 wt.% ethylene-based polymers, specifically an ethylene-based copolymer such as ethylene/butyl acrylate, ethylene/ethyl acrylate, ethylene/methyl acrylate, or ethylene/vinyl acetate, which is less than 20% of the total film thickness, enhancing tear resistance and recyclability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If multilayer films incorporate various materials (polypropylene, polyamide, polyethylene terephthalate) to achieve good performance and tear resistance, then the film performance is improved, but the recyclability deteriorates due to incompatibility of different materials
Solution Approach 1:
The patent applies homogeneity by using ethylene-based copolymer as the core layer material, which is compatible with polyethylene recycling streams. This ensures that the core layer can be recycled together with the outer layers made of polyethylene, creating a homogeneous recycling pathway that resolves the incompatibility issue while maintaining tear resistance through the specific copolymer composition
Solution Approach 2:
The patent changes the material parameter of the core layer to ethylene-based copolymer with specific composition ratios (ethylene content 40-80 wt%, comonomer content 20-60 wt%). This parameter change enables the core layer to be recyclable with polyethylene streams while maintaining the necessary mechanical properties and tear resistance through controlled copolymerization
2Strength
If a thick core layer is used to improve tear resistance, then the tear resistance is improved, but the film thickness increases and recyclability may be compromised
Solution Approach 1:
The patent optimizes the core layer thickness parameter to less than 20% of the total film thickness while using ethylene-based copolymer with specific composition (ethylene content 40-80 wt%). This parameter optimization achieves the necessary tear resistance through the copolymer's inherent mechanical properties rather than relying on increased thickness, thereby maintaining film simplicity and recyclability
Data Source
AI summary
Provided are multilayer films including ethylene-based copolymers. The multilayer films can be fully compatible with polyethylene recycling streams. The multilayer films comprise a first outer layer, a second outer layer, and a core, the core including a first core layer that includes an ethylene-based copolymer selected from the group consisting of ethylene/butyl acrylate copolymer, ethylene/ethyl acrylate copolymer, ethylene/methyl acrylate copolymer, and ethylene/vinyl acetate copolymer. The first core layer according to embodiments disclosed herein is less than 20% of the total thickness of the multilayer film. The multilayer films of the present invention can exhibit improved or desirable properties, such as high tear resistance, in comparison to existing multilayer film structures.