Multi-Material Extruded Zipper with TPU Core and PTFE Coating
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Solution Overview
Problem
Olefin-based polymer zipper systems, commonly used in applications like sandwich bags, lack durability and performance in extreme environments due to low tensile and tear strength, excessive compression set, and require frequent lubrication for low friction, making them unsuitable for applications like drybags and wet-suits.
Innovation Solution
A multi-material extruded zipper (MMEZ) is developed using Thermoplastic Urethane (TPU) with a low coefficient of friction (LCOF) coating applied strategically during the tri-extrusion process, combining materials with different durometers for high strength, flexibility, and low friction surfaces, eliminating the need for frequent lubrication and enhancing durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If Olefin-based polymer (polypropylene/polyethylene) is used for zipper profiles, then low cost and low coefficient of friction are achieved, but tensile strength, tear strength, elongation properties, and compression set resistance deteriorate
Solution Approach 1:
The patent applies composite materials by combining TPU (thermoplastic polyurethane) as the base material with PTFE (polytetrafluoroethylene) as a coating layer. The TPU provides high tensile strength, tear strength, and elongation properties, while the PTFE coating provides low coefficient of friction. This composite structure resolves the contradiction between cost/ease of manufacture and mechanical strength by integrating the advantages of both materials.
Solution Approach 2:
The patent applies local quality by coating only the specific surfaces that require low friction (the ball and socket contact surfaces) with PTFE, while the rest of the zipper profile maintains the TPU material properties for strength and durability. This localized application of different material properties optimizes both friction reduction and mechanical strength without compromising overall performance.
2Ease of operation
If Olefin-based polymer is used for zipper profiles, then low coefficient of friction is achieved, but durability in extreme temperature environments and compression set resistance deteriorate
Solution Approach 1:
The TPU-PTFE composite material system resolves this contradiction by combining TPU's superior durability, temperature resistance, and compression set resistance with PTFE's low friction properties. The TPU base material maintains structural integrity in extreme environments while the PTFE coating ensures easy operation through low friction.
Solution Approach 2:
The patent changes the material parameters by selecting TPU with specific durometer ranges (Shore A 85-95 or Shore D 60-70) and coating with PTFE having a coefficient of friction of 0.04-0.08. These parameter optimizations ensure both ease of operation and reliability in extreme temperature conditions from -40°F to 200°F.
3Ease of manufacture
If single-material extrusion is used, then manufacturing simplicity is maintained, but inability to achieve both low friction surfaces and high strength simultaneously
Solution Approach 1:
The patent uses co-extrusion technology to manufacture a composite zipper profile in a single manufacturing step. The TPU core material provides structural strength while the PTFE outer layer provides low friction. This composite approach maintains manufacturing simplicity compared to post-manufacturing coating processes while achieving both low friction and high strength properties simultaneously.
Solution Approach 2:
The patent merges the manufacturing of two different materials (TPU and PTFE) into a single co-extrusion process. This combining of materials and processes allows the zipper profile to be manufactured in one step with both low friction and high strength properties integrated, rather than requiring separate manufacturing and assembly steps.
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 MMEZ provides easy insertion and difficult extraction, maintaining low friction without reapplication, and exhibits superior compression set resistance and sealing flexibility, suitable for extreme outdoor applications like drybags and waterproof garments.
Implementation Method 1
extruding, as part of a tri-extrusion process, a first material, the first material forming a leading edge of a ball portion of the zipper and the first material forming an opening for a socket
Implementation Method 2
the first material having a low coefficient of friction
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
A zipper includes a ball portion. The zipper portion further includes a socket portion. The ball portion includes a leading edge, the leading edge composed of a first material having a low coefficient of friction. The ball portion includes a trailing edge and a neck portion, the trailing edge and neck portion composed of a second material. The socket includes a socket opening, the socket opening composed of the first material. The socket includes a socket interior, the socket interior composed of the second material.