超臨界微細發泡射出成型熱塑性彈性體聚胺脂之品質控制研究

Study of Microcellular Injection Molded Thermoplastic Elastomer TPU in Foaming Quality Control

姚睿(Jui Yao)

指導教授 ： 陳夏宗

中原大學/工學院/機械工程研究所/碩士(2017年)

https://doi.org/10.6840/cycu201700322

摘要

超臨界微細發泡射出成型是利用惰性氣體當發泡劑的一項製程，透過發泡劑使得產品內部有泡體產生，並能輕量化、環保及節能等優點，而目前市面上的鞋底大多使用EVA材料，但是對於耐磨性與壽命是相對較差的，也因為鞋底的形狀非常複雜，因此在成型上泡體的控制難度較高，而影響產品的關鍵因素為模具設計與參數設定，因此本研究則主要利用參數對於熱塑性彈性體聚胺脂在超臨界微細發泡射出成型製程中產品內部泡體的控制進行探討。
本研究針對模具溫度、射出速度及超臨界流體含量探討參數對泡體的影響。發現在模具溫度提高時，凝固層減少72.4%，泡體成長時間增加，因此泡體的平均尺寸提升33.7%，密度降低34.3%，硬度減少4.01%；當射出速度越快時，前段與中段因為壓力降較小，更容易控制泡體，平均泡體尺寸降低22.5%，密度增加51.7%，硬度增加2.3%；超臨界流體含量的增加，使得產品後段的泡體分佈有所提升，泡體尺寸減少1.6%，密度增加14.2%，硬度也提升1.7%。
再來將最佳參數應用在不同的減重程度上進行探討，可以得知即便在40%較低的減重程度下，透過最佳參數的改善能使泡體的尺寸及密度的均勻性有大幅的改善；而在60%的減重程度，泡體尺寸有增加的趨勢，但是在整體的均勻性也是能有明顯的提升；而在80%較高的減重程度上，因為原料的體積過少，無法透過最佳參數控制使泡體成長將產品填滿完整個模穴。因此，均勻性的改善應用在鞋底，能夠大幅提升穿著的舒適度。

關鍵字

超臨界微細發泡射出成型 ； TPU ； 減重程度

並列摘要

Microcellular injection molding use inert gas to be the vesicant, through the foam makes the product inside the bubble generation, and the advantages of this process has lightweight, environmental protection and energy saving. The most of soles are made of EVA on the market currently. Also the shape of soles is very complex, so the bubble in the soles is more difficult to control. The mold design and parameter setting are the factors to effect the product. In this study, using thermoplastic elastomer polyurethane with different parameter to control the bubble in the microcellular injection molding.
In this study, the effects of parameters on the mold temperature, injection rate and the supercritical fluid dosage were discussed. It was found that the skin layer decrease 72.4% when the mold temperature was increased. And the average cell size increased 33.7%, the cell density decreased 34.3% and the hardness decreased 4.01% because of the time of foaming increased. When the injection rate increase, the front and the middle of product have smaller pressure drop, so it’s more easier to control the bubble, so the average cell size reduced 22.5%, the cell density increased by 51.7%, the hardness increased by 2.3%. When the supercritical fluid dosage increased, the distribution of cell in the product improved, and the cell size decreased 1.6%, the cell density increased 14.2%, hardness also increased 1.7%.
And last part will discuss the best parameter applied in different light weight level. It’s found that the beat parameter can improve the cell size and density to be more uniform in the 40% light weight level. In the 60% light weight level, the cell size and density of foam of uniformity is significantly improved with best parameter. In other ways, it can’t fill the cavity by using best parameter to control the foaming in 80% weight reduce because of the volume of materials is too little. Therefore, the improvement of the uniformity is applied to the soles, and the comfort of wearing can be greatly improved.

並列關鍵字

Microcellular injection molding ； TPU ； Weight reduce

參考文獻

9.鍾明修，“超臨界微細發泡射出成型製成特性之研究”，中原大學博士論文，2006

15.許評順，”模內氣體反壓與動態模溫機制應於超臨界微細發泡射出成型發泡控制與表面品質影響之研究“，中原大學博士論文，2011

10.K. T. Okamoto, "Microcellular Processing", Hanser Gardner Publishers ,2003.

2.J. S. Colton and N. P. Suh, "Nucleation of Microcellular Foam: Theory and Practice", Polymer Engineering and Science,1987.

3.C. B. Park and N. P. Suh, “Extrusion of microcellular polymers using a rapid pressure drop device”, Society of Plastic Engineers Technical Papers,1993.