- 學位論文
微米球自組裝製作模具用於滾壓光學擴散膜的應用
Application of Microsphere Self-assembly Mold in Rolling Diffusion Film
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摘要
在透明塑膠薄膜上製作微結構，如微透鏡陣列、或V-溝等，成為光學膜，能大幅提升光學功能與附加價值。為了提升製程連續性，達到大量生產的目的，滾筒微壓印技術被廣泛使用。然而，其中關鍵的滾筒模具製作，挑戰仍大。因為微結構位於曲面，無論用機械加工、雷射加工都精度受限且成本高；而將平面模具包覆在滾筒必留有接縫。本研究在玻璃圓管壁內，以自組裝微米球方式製作無縫母模，再套入軸心，以PDMS澆鑄，製作無縫滾筒模具。 本研究以氣液介面法(浸潤塗佈法)，使5微米直徑微米球自組裝於玻璃圓管內壁。首先探討不同表面活性劑用量、管壁溫度、液面下降速度等參數，對於微米球堆積表現的影響。實驗結果顯示使用0.3 ml表面活性劑時，堆積表現較佳 (堆積高度達35 mm)；液面下降速度0.96 µm/s，且管壁溫度為50°C時，堆積覆蓋率較佳(81.34%)。本研究也提出並證實移動加熱位置、基材預熱等方式，改善玻璃圓管溫度及梯度。此外，本研究創新以輔助圓錐，使液面下降時，微球仍靠近圓管壁，進一步促進微球自組裝排列，結果顯示有輔助圓錐，堆積高度可提升3.34倍。完成堆積後，在玻璃圓管中心放置水溶性PVA軸心，以PDMS澆鑄；待PDMS固化後，將水溶性軸心移除，改插入PLA軸心，得到無縫圓筒模具，可用來製作擴散膜。 本研究進一步架設UV光固化滾壓機台，使用所製作的無縫圓筒模具，在0.11 mm之PET膜上，以UV光固化技術，滾壓出有微結構的光學膜，驗證確實具有擴散點光源效果，本研究證實使用自組裝微奈米球製作無縫滾筒模具的潛力。
並列摘要
The hot rolling process is widely used in the fabrication of optical films, such as microlens arrays and optical diffusion films, enabling efficient large-area microstructure replication on polymer films. To enhance the continuity of the process and achieve mass production, roller micro-imprinting technology has been developed. However, manufacturing the key component, namely, the roller molds, with microstructures on curved surfaces, pose significant challenges and high cost. In this study, a master mold is on the inner wall of a 40 mm-diameter glass tube using the self-assembly of 5 µm polystyrene(PS) microspheres. Then a core is placed in the center. PDMS is cast. After curing, a seamless microstructured roller mold is fabricated. The gas-liquid interface method (dip coating method) is used to self-assemble microspheres on the inner wall of the glass tube. First of all, the effects of surfactant amounts, tube wall temperatures, and liquid level descent rate on the microsphere stacking performance are investigated. The experimental results show that using 0.3 ml of surfactant results in the highest stacking (35 mm); a liquid level descent rate of 0.96 µm/s and a tube wall temperature of 50°C lead to best stacking coverage (81.34%). Secondly, the effects of preheating the glass tube, and descending the position of graphene-composite heating band to increase the temperature and to improve the temperature gradient of the glass tube on the stacking performance are also investigated. Last but not least, to increase the density of microspheres as the water level descending, a 3D-printed resin cone is placed in the center of the glass tube. With the aid of resin cone, the stacking height is increased to 3.34 times of the height without cone. After the microspheres are self-assembled on the glass wall, it becomes the master mold. A water-soluble PVA core is then placed in the center of the glass, and PDMS is cast. Once the PDMS cured, the water-soluble core is dissolved and a PLA core is inserted, a seamless cylindrical mold is successfully made. An UV curing rolling facility, using the fabricated seamless cylindrical roller mold is designed and implemented. Microstructures are imprinted on a 0.11 mm PET film using UV curing rolling machine. An optical film is fabricated. Point light source has been diffused and the diffusion function has been verified. This study confirms the potential of using self-assembled micron- and nano-spheres for fabricating seamless roller molds.
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