Thin Multilayer PCR Films for Tear Strength Retention
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Solution Overview
Problem
Incorporating post-consumer recycled (PCR) plastic materials into plastic products, such as trash bags, often degrades their mechanical properties, particularly tear strength, making it difficult to meet regulatory requirements and maintain quality.
Innovation Solution
Developing thin multilayer films with significant PCR plastic content, blended with standard plastic resins, that maintain robust mechanical properties by controlling melt flow index and leveraging distinct morphologies of PCR materials, such as white and unpigmented PCR plastics, to enhance tear strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If post-consumer recycled plastic materials are incorporated into plastic products, then the environmental sustainability and regulatory compliance are improved, but the mechanical properties particularly tear strength are degraded
Solution Approach 1:
The film is divided into multiple layers with different compositions. The core layer contains high percentages of PCR plastic materials (up to 90%) while the skin layers contain lower percentages or different types of polymers. This segmentation allows the film to meet sustainability goals in the core while maintaining mechanical integrity in the skin layers that contact the environment.
Solution Approach 2:
The invention uses composite material structures combining PCR plastic materials with virgin polymers in specific layer configurations. By creating a multilayer composite film where different materials are strategically placed, the film achieves both high PCR content for sustainability and robust mechanical properties through the synergistic combination of recycled and virgin materials.
2Reliability
If high percentages of PCR plastic materials are used, then the regulatory compliance and environmental goals are improved, but the tear strength and mechanical properties deteriorate
Solution Approach 1:
Different regions of the film have different material compositions optimized for their specific functions. The core layer uses high PCR content for compliance, while the skin layers use materials optimized for mechanical strength and environmental resistance. This local quality differentiation allows each layer to perform its specific function optimally.
Solution Approach 2:
The invention changes the compositional parameters of different film layers, using varying percentages of PCR materials, different polymer types, and adjusted molecular weights in each layer. By optimizing these parameters locally in each layer, the film achieves both regulatory compliance and mechanical performance.
3Reliability
If multilayer films with high PCR content are manufactured, then the sustainability and recycling goals are improved, but the manufacturing complexity and process difficulty increase
Solution Approach 1:
The manufacturing process is segmented into separate layer extrusion steps, allowing each layer to be optimized independently. This segmentation simplifies the overall manufacturing process by enabling specialized equipment and processes for each layer type rather than requiring a single complex process to handle all materials simultaneously.
Solution Approach 2:
The invention uses intermediary materials and processing aids that facilitate the extrusion of multilayer films with different compositions. These intermediaries help align the different materials during extrusion and maintain layer integrity, simplifying the manufacturing process despite the complexity of combining multiple materials.
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 multilayer films achieve tear strengths comparable to those made from 100% virgin resin, with PCR content ranging from 20% to 90%, significantly improving tear resistance over prior art films.
Implementation Method 1
the blends of such material typically have a melt flow index of 0.6 g/10 min at 190° C./2.16 kg (as tested in accordance with ASTM D1238) or greater
Data Source
AI summary
Thin multilayer films fabricated from molten blends of stock plastic resin and post-consumer recycled plastic materials are described. The thin multilayer films maintain robust physical and mechanical properties as compared to thin films fabricated from stock plastic resins and as compared to prior art multilayer films that incorporate PCR plastic materials. Generally, the thin multilayer films with post-consumer recycled plastic maintain at least 70% of the value of a mechanical property when compared to film without the post-consumer recycled plastic material. The multilayer film may contain about 60% post-consumer recycled plastic materials yet maintain structural integrity. The multilayer film may include white or unpigmented post-consumer recycled plastic materials or a blend of white and unpigmented post-consumer recycled plastic material.