Recyclable Multilayer Ethylene Films With High Tear Resistance
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Solution Overview
Problem
Multilayer films incorporating different materials are difficult to recycle due to incompatibility, despite requiring high tear resistance for industrial applications.
Innovation Solution
Development of multilayer films with a core comprising 100% ethylene-based polymers, specifically an ethylene-propylene copolymer, which are fully recycle-compatible and maintain comparable or improved tear resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If multilayer films incorporate different materials (polypropylene, polyamide, polyethylene terephthalate) to achieve good performance and tear resistance, then the films exhibit sufficient tear resistance and performance, but the films become difficult or impossible to recycle due to material incompatibility
Solution Approach 1:
The patent applies homogeneity by using only ethylene-based polymers (specifically LLDPE and LDPE) for all layers of the multilayer film. This ensures that the entire film structure is composed of compatible materials that can be easily recycled together, eliminating the recyclability problems caused by mixing incompatible polymers like polypropylene, polyamide, and polyethylene terephthalate. The homogeneous material composition maintains tear resistance while enabling full recyclability in polyethylene streams.
2Ease of manufacture
If multilayer films use 100 wt.% ethylene-based polymers in the core to ensure recyclability, then the films are fully recycle-compatible, but achieving comparable or improved tear resistance becomes more challenging
Solution Approach 1:
The patent applies composite materials by creating a multilayer structure where the core layer consists of 100 wt.% ethylene-based polymers (LLDPE and LDPE) while the outer layers can include different ethylene-based polymers. This composite approach allows the core to provide recyclability while the specific composition and thickness of each layer are optimized to achieve comparable or improved tear resistance. The multilayer composite structure enables both recyclability and mechanical performance.
Solution Approach 2:
The patent applies parameter changes by carefully selecting the density, molecular weight, and thickness parameters of the ethylene-based polymers used in each layer. The core layer uses LLDPE with density 0.910-0.940 g/cm³ and LDPE with density 0.915-0.965 g/cm³, with specific thickness ratios between core and outer layers. By optimizing these parameters, the film achieves both full recyclability and the required tear resistance performance.
Data Source
Figure 1
AI summary
Provided are multilayer films including ethylene-based polymers. 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-propylene copolymer. The multilayer films of the present invention can exhibit improved, maintained, or desirable properties, such as high tear resistance, in comparison to existing multilayer film structures that are not fully compatible with polyethylene recycling streams.