曝光量與版材硬度對於柔版印刷品質之影響

Abstract

本研究主要針對柔版製版的過程做探討，選定的研究因子為：版材硬度、背曝光時間以及正曝光時間。探討的反應變量為：2%網點擴大、10%網點擴大、50%網點擴大、90%網點擴大、滿版濃度以及印刷反差。經由23全因子實驗設計，得到了8種配方。經由實際的印刷機測試後，得到了待分析的印刷樣張。藉由分光濃度計的量測，得到了原始的印樣數據。最後經由統計軟體實施各種的統計分析後，得到以下的結論：對2%及10%網點而言，版材硬度及正曝光時間是顯著的因子。較硬的版材及較短的正曝光時間有助於降低網點擴大的程度。對於50%及90%網點而言，情況竟然相反，這時較軟的版材反而使得網點擴大的程度降低。相較於版材硬度，背曝光時間與正曝光時間這2個因子在50%及90%網點處，則沒有太顯著的效用。相同的情形亦出現在滿版濃度與印刷反差這2個反應變量上。因此，在本研究中，就影響程度而言，版材硬度對於瓦楞紙板印刷是有最顯著影響程度的。而背曝光時間，則對於各個反應變量的影響程度最小，甚至是不顯著。The main purpose of this research was intended as an investigation of the impact of different exposures and hardness of the photopolymer plates on flexographic printing quality. The hardness of the photopolymer plates, back exposures and main exposures were independent variables in this research. The concerns were to examine the variations and differences of dot gain, solid ink density and print contrast, which were resulted from the three independent variables. A 23 full factorial experiment was used for the study. Through the design of experiments, eight treatments for the practical printing experiment were constructed. The resulting printed dot areas were measured and analyzed statistically. The following conclusions were found: (1) the hardness of the photopolymer plates and main exposures were the significant factors at 2% and 10% dot areas, and (2) the harder photopolymer plates and the shorter main exposures could reduce the dot gain significantly. In contrast, (3) the softer photopolymer plates reduced more dot gain than the harder one did at 50% and 90% dot areas. To sum up, the hardness of photopolymer plates has the highest degree of impact on corrugated printing among the three independent variables. In comparison,the back exposures had less, even not significant, impact on flexographic printing quality.