Injection Moulding Thermoplastic Polyester Elastomer Mesh
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Solution Overview
Problem
Conventional injection moulding techniques are unable to produce mesh articles with fine enough members to achieve desired resilience through strain orientation, particularly with materials like HYTREL, as they tend to break rather than strain orient when following recommended moulding conditions.
Innovation Solution
A method of injection moulding a polymeric resin, specifically using a thermoplastic polyester elastomer like HYTREL, where the resin is heated to at least 240°C, injected into a mould to form a sheet with elongate members and apertures, and then stretched and relaxed to achieve strain orientation, allowing for the production of resilient mesh articles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional injection moulding conditions are used (melt temperature of about 225°C and mould temperature of between 30°C and 40°C), then the material can be processed, but the members of the formed mesh article break rather than strain orienting
Solution Approach 1:
The patent changes the injection moulding parameters by increasing the melt temperature to at least 240°C and adjusting the mould temperature to between 40°C and 80°C. These parameter changes modify the material's flow and cooling characteristics, enabling the formation of sufficiently fine mesh members that can undergo strain orientation without breaking, thus resolving the contradiction between member integrity and strain orientation achievement.
2Strength
If the mesh members are made finer to achieve desired resilience, then the article can strain orient, but the members break under conventional moulding conditions
Solution Approach 1:
By increasing the melt temperature to at least 240°C and adjusting the mould temperature to between 40°C and 80°C, the patent enables the production of finer mesh members with cross-sectional dimensions of 2.5 mm or less that maintain sufficient strength and ductility to undergo strain orientation without breaking, thereby achieving both desired resilience and member survival.
3Manufacturing precision
If laser cutting is used to form mesh articles with apertures, then fine members can be achieved, but the manufacturing cost increases significantly
Solution Approach 1:
The patent replaces the mechanical laser cutting process with an injection moulding process that uses controlled material flow and cooling to directly form fine mesh members. By optimizing the injection parameters (melt temperature of at least 240°C, mould temperature of 40°C to 80°C), the process achieves the same level of manufacturing precision for mesh members without the high costs associated with laser cutting, especially for large-scale production.
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
This method enables the production of strain-oriented mesh articles with elongate members that can be stretched significantly without failure, enhancing the material's strength and elasticity, overcoming the limitations of conventional techniques.
Implementation Method 1
heating the resin to form a molten resin at a temperature of at least about 240°C
Implementation Method 2
stretching at least part of the sheet part of the formed article having an as-moulded dimension so as to have a stretched dimension and such that strain orientation of at least part of the sheet part of the formed article occurs
Implementation Method 3
relaxing the formed article so as to have a post-relaxation dimension between the as-moulded dimension and the stretched dimension
Data Source
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AI summary
A method of injection moulding a polymeric resin to form an article that is suitable for strain orientation. A thermoplastic polyester elastomer polymeric resin is provided. The resin is heated to form a molten resin at a temperature of at least about 240°C. The molten resin is injected into a mould (22) to substantially fill the mould and form an article. At least part of the article is a sheet part with a plurality of members that are integrally formed into the sheet part, with apertures provided between at least some of the members of the sheet part of the article to form a mesh. At least the sheet part of the article is suitable for strain orientation.