Polyethylene Molded Articles Using PTFE for Reduced Weight and Barrier Performance
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Solution Overview
Problem
Molded articles made from polyethylene often face a trade-off between reducing weight and maintaining barrier performance against air, moisture, and contaminants, with existing additives being expensive and difficult to disperse, particularly in food contact applications where regulatory compliance is stringent.
Innovation Solution
The development of molded articles using a polymer composition comprising an ethylene homopolymer or ethylene/alpha-olefin copolymer with specific density, melt index, and molecular weight distribution, combined with greater than 20 ppm of polytetrafluoroethylene, which enhances barrier properties while allowing for reduced material usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the amount of material in molded articles is reduced to decrease weight, then shipping costs are lowered, but barrier performance against air, moisture and contaminants deteriorates
Solution Approach 1:
The patent combines polyethylene with polytetrafluoroethylene (PTFE) to create a composite material system. The PTFE, present as discrete particles dispersed throughout the polyethylene matrix, provides enhanced barrier properties against oxygen, moisture, and contaminants. This composite approach allows the molded article to maintain superior barrier performance even when wall thickness is reduced, thereby enabling weight reduction without sacrificing reliability.
2Reliability
If typical nucleating agents are used to improve barrier performance, then barrier properties are enhanced, but manufacturing cost increases and dispersion difficulty increases
Solution Approach 1:
The patent replaces expensive, difficult-to-disperse nucleating agents with polytetrafluoroethylene (PTFE) particles, which are more cost-effective and easier to incorporate into the polyethylene matrix. The PTFE particles serve as both a barrier enhancement agent and a functional additive, eliminating the need for separate nucleating agent steps in manufacturing. This substitution reduces both material costs and processing complexity while maintaining improved barrier performance.
3Reliability
If typical nucleating agents are used to improve barrier performance, then barrier properties are enhanced, but additive cost increases
Solution Approach 1:
The patent substitutes expensive nucleating agents with polytetrafluoroethylene (PTFE), which provides comparable or superior barrier enhancement at lower cost. The PTFE particles can be incorporated during standard polymer processing without requiring additional expensive additives, thereby reducing the overall bill of materials while achieving the desired barrier performance for food contact applications.
4Reliability
If polytetrafluoroethylene is added to enhance barrier properties, then oxygen transmission rate is reduced, but material complexity increases
Solution Approach 1:
The patent creates a composite system by combining polyethylene with polytetrafluoroethylene (PTFE) particles. The PTFE is incorporated as a dispersion of particles within the polyethylene matrix during standard injection molding processing. This composite approach provides enhanced barrier properties against oxygen and moisture transmission while maintaining compatibility with existing manufacturing processes, thereby limiting the increase in material complexity to what is necessary for achieving superior performance.
Data Source
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AI summary
A molded article formed from a polymer composition, the polymer composition consisting essentially of: an ethylene homopolymer or ethylene/alpha-olefin copolymer; greater than 20 ppm of a fluoropolymer; and optionally, up to 5 wt.% of one or more of processing aids, acid neutralizers, stabilizers, phosphites, antioxidants, metal de-activators, pigments or colorants, or fillers; wherein the molded article exhibits an oxygen transmission rate [OTR, (cc*mm)/(m2*day*atm)] ? -3181 (cc2*mm)/g*m2*day*atm) X [Density, g/cc] + 3077, (cc*mm)/(m2*day*atm).