射出壓縮製程對光碟片雙折射影響之研究

Study on the Effect of Disc Birefringence with the Injection Compression Molding Process

李紹緯(Shao-Wei Li)

指導教授 ： 陳夏宗

中原大學/工學院/光機電及資電控產業研發碩士專班/碩士(2007年)

https://doi.org/10.6840/cycu200700131

摘要

本研究探討射出壓縮成型條件對光碟片的雙折射之影響。在射出成型之過程中，可能因為熔膠的流動及溫度影響，導致不均勻分子排向以及不均勻壓力之分佈，這些因素均會造成雙折射現象之發生。由於雙折射太高會造成反射率偏低，可能導致光碟機在讀取光碟片時造成訊號的干擾，雷射光聚焦尋軌讀取時便發生困難，而在光碟片朝高密度、高容量、高倍速的發展下，必須把雙折射值降低，因此須了解製程參數對雙折射的影響。
研究中使用光學級之聚碳酸酯(帝人PC AD-5503)為實驗塑料，所考慮之射出成型條件有射出時間、熔膠溫度、模具溫度、保壓壓力、保壓時間、初始合模距離與後壓縮力等。研究中使用物理特性測試機MT-136，觀察射出成型條件對成型品雙折射光學性質之影響，以期可以找出每個成型條件對實驗結果之影響程度。
在成型參數中，射出時間為0.25秒時，雙折射值為8nm；射出時間為0.4秒時，雙折射值為36nm。實驗結果顯示，縮短射出時間有助於降低光碟片內徑的雙折射值；隨著射出時間增加，因為熔膠流動速度減緩，流動應力變大造成內徑的雙折射會增加。熔膠溫度升高能夠降低內徑的雙折射，而模具溫度的影響是比較有限的；保壓壓力與後壓縮力增加，會使雙折射值增加。初始合模距離由0.1mm增加至0.6mm，內徑的雙折射減少23nm，而外徑的雙折射會略微增加9nm。

關鍵字

射出壓縮 ； 聚碳酸酯 ； 雙折射

並列摘要

This study probes on the effect of disc birefringence with the injection compression molding process. In injection process, the melt flow and temperature may cause unbalanced molecular orientation and distribution of pressure and these factors will cause birefringence. The higher birefringence results in lower reflective value, and it may cause the interference of the signal while reading the disc. Towards the developments of high density, high capacity and high speed disc, it is very important to realize the injection compression molding process relatively to birefringence and reduce the birefringence.
In this study, the material was optical grade polycarbonate (Tejin PC AD-5503), and the process parameters included filling time, melt temperature, mold temperature, packing pressure, initial clamp distance, and clamp force., the physical characteristics of disc birefringence was measured by test machine MT-136.
Filling time in 0.25 second, the birefringence result is 8nm, and in 0.4 second, the birefringence result is 36nm. The experimental results point out that the shorter filling time results in lower birefringence value. With filling time increasing, the residual stress become larger to cause birefringence increase in reducing filling velocity. Higher melt temperature reduces birefringence value, but higher mold temperature is not very significant. Higher packing pressure and clamp force result in higher birefringence values. Initial clamp distance increasing from 0.1mm to 0.6mm, the inner of disc birefringence value reduce 23nm, and the outer of disc birefringence value increases 9nm slightly.

並列關鍵字

Polycarbonate ； Injection compression molding ； Birefringence

參考文獻

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