噴塗程序需將所需液體均勻的覆蓋於被覆蓋物上，而液滴噴塗上去的過程會直接影響被覆蓋物的品質。本研究擬以純水液滴撞擊親水性高分子平板，藉高速攝影技術之便利，來探討、模擬噴塗過程中液滴所表現的潤濕行為。
液滴碰撞平板後的潤濕行為與液體本身的物理性質（密度、黏度、表面張力等）、撞擊速度、液滴大小、平板物性（粗糙度、親疏水性）皆有關係。本研究以高速攝影機連續拍攝液滴撞擊平板後的液滴形態變化和潤濕行為，另分析液滴撞擊後液滴捕捉氣泡的行為。
本研究先以不同液滴大小的純水液滴撞擊親水性PVC平板，以We (韋伯數)、Re (雷諾數)、撞擊速度和氣泡面積來分析氣泡捕捉趨勢，再以Dw (潤溼直徑)、H (液滴高度)及CA (接觸角)來分析針號#28、#20及#16的不同大小液滴之氣泡捕捉機制與行為。
本研究獲得下列資訊：純水液滴撞擊PVC表面，氣泡捕捉之操作條件僅限於在Vi - D0圖上的一個半封閉的區間；氣泡捕捉之撞擊速度的上限和下限，因著液滴直徑D0之增加而下降； 而當固定液滴尺寸時，Re-We 曲線有單調遞增的趨勢；且此單調遞增的關係取決於液滴大小。隨著捕捉到最大氣泡的直徑增加與該氣泡直徑對應之速率成反比。由針號28的液滴來分析，撞擊速度越快的，液滴高度較低，變化也較快;反之，撞擊速度越慢的，液滴高度較高，變化也比較慢，成正相關。捕捉到氣泡的液滴震盪較不受到高度的影響;受到氣泡捕捉的影響，液滴撞擊平板後的液滴高度最低點都正常的液滴高。此外液滴大小直接影響液滴的行為變化，在相近的速度上，直徑越小的液滴，液滴擴張回縮的行為越快;反之液滴直徑越大，行為變化較慢。

In this work, the wetting phenomenon, drop morphology and bubble-entrapment behavior were studied for water drop impinging on PVC polymer surface. These phenomena during the drop impact are dependent upon the liquid properties (density, viscosity and surface tension), impact velocity, drop size, and solid properties (roughness and surface hydrophobicity). A high speed video camera was utilized for this study and both the images of the side view and 45 degree topic view were recorded continuously.
Water drops of different sizes were used on the impact study onto the PVC planar surface. The relaxations of drop wetting diameter, drop high and contact angle were recorded for studying the wetting phenomenon from the side view images. The bubble entrapment behavior was investigated from the 45 degree topic view images. Three drop sizes (D0 =2.38, 3.14, and 3.87 mm) were used in this work.
We observed the following phenomena from this study: (i) , (ii), (iii) and (iv).
(i)A half closed region on the Vi-D0 plot was identified for the formation of entrapped bubble. The upper and lower boundaries of Vi showed a tendency of decreasing as D0 increases. The entrapped bubble generally resulted in a hemispherical bubble after settling down on PVC surface.
(ii)The Re-We curve increase depend on the drop size increase.
(iii) With the analyze of needle 28, diameter of maximum bubble inverse with speed of impact. And impact speed also inverse with drop height.
(iv) The lowest height of drop with bubble is higher than the normal one. What’s more is drop size affect drop behave directly.

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