氣體反壓與動態模具溫控技術應用於熱塑性彈性體高減重比之超臨界微細發泡射出成型泡體均勻性之研究

Study of Foaming Uniformity Control of High Weight Reduction Microcellular Injection Molded Thermoplastic Elastomer

李冠樺(Kuan-Hua Lee)

指導教授 ： 陳夏宗

中原大學/工學院/機械工程研究所/博士(2017年)

https://doi.org/10.6840/cycu201700851

摘要

超臨界微細發泡製程兼具環保節能、省料、縮短循環周期、降低成本等優點，被廣泛應用，舉凡汽車工業、包裝應用、3C 家電、工業用零組件都涵蓋在內，在這些新興應用中，鞋底市場也不容忽視。熱塑性彈性體聚氨酯在眾多彈性材料中具有高耐磨，高彈性，抗疲勞，耐化學性等諸多優點，非常適合作為球鞋大底的材料，但也因為其比重大，硬度高，減震性能較差尚未完整應用在發泡中底的成型上。在目前MuCell® 製程應用於高減重比之
聚氨酯之成型上主要問題在於純 MuCell® 成型對於產品前、中、後段之發泡均勻度以及厚度方向皮層至核心層的均勻度較差，進而影響鞋底最重要的彈性性質。
本研究將氣體反壓以及動態模具溫度控制技術導入 MuCell® 成型鞋底的製程中，分別透過泡體平均尺寸、發泡密度、泡體各尺寸數量分佈以及硬度的探討釐清找出最佳控制參數，使得整體泡體尺寸及均勻度改善。研究結果顯示透過動態模溫控制在高溫充填低溫冷卻的情況下，可以將平均泡體抑制在 10~20µm 內且有 40%以上之 20~40µm 泡體；透過氣體反壓技術則可將超臨界含量 1.0wt%之試片泡體均質抑制在 10~50µm 的區間內且超過50%泡體尺寸數量集中在 10~30µm；最後在協同控制的部份則可將泡體平
均質以及 84%數量集中在 20~40µm 的區間內，達成均勻度之改善。

關鍵字

超臨界微細發泡成型 ； 泡體控制 ； 熱塑性彈性體 ； 減重比

並列摘要

Microcellular injeciton molding process is widely used in different industry including automotive, packaging, sporting goods, industrial and electrical parts since Mucell process itself offers many advantages such as material and energy saving, low cycle time, cost effective and dimension stability of the products.
Thermoplastic Polyurethane (TPU) is a common material for molding the outsole of shoes because of its outstanding properties such as hardness, abrasion resistance, and elasticity. Many shoe manufacturers started to apply Mucell® process into TPU midsoles manufacturing, but yet still has several problems to move in mass production, the main problem needs to be solved is the uniformity of the cell size in the midsole, the cell size will be affected by injection process induced pressure drops which lower the cell size uniformity in different region and lower the bouncing properties. To solve this problem, dynamic mold temperature control and gas counter pressure technology were applied to achieve the uniform cell size distribution midsole using Mucell process in this study. Several process parameters were compared and discussed through average cell diameter distribution, cell density, hardness and uniformity of the cells. The results show that 40% of cell diameter can be controlled within 20~40µm under DMTC and 50% of the cells diameter can be controlled into 10~30 µm under GCP. The best results which combine DMTC and GCP into Mucell process can achieve
over 80% of the cell size within 20~40µm improve the uniformity of midsole manufacturing.

並列關鍵字

Microcellular injection molding ； cell size control ； thermal plastic elastomer ； weight reduction

參考文獻

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