數位印刷PET薄膜於模內轉印品質色彩特性之研究
中文摘要
模內轉印技術能在不規則物體表面印刷出極佳的質感與效果，許多產品外殼在經過立體轉印彩裝後具備防水、不褪色，達到保護、美化、宣傳的功能，產品整體質感提高，創造更多經濟價值。但目前模內轉印之前作業大多使用凹版或網版印刷印製 PET轉寫薄膜；凹印製程複雜，成本很高；網印雖成本較低，但印刷半色調品質很差，較適用於量大之產品，且較少應用在彩色印刷；同時對產生高線數影像有所限制，印墨溶劑也有公害問題；目前的市場趨勢越趨傾向開發個性化市場，因此本研究以數位印刷(含光電與噴墨)的方式，應用其輸出列印不需製版、節省製程成本、時效縮短、同時圖文影像精細且又能創造個性化塗裝效果等特點。為更深入研究數位印刷應用於膜內轉印製程，分成兩年實驗進行，第一年以不同塗料研究其材料特性，同時亦進行光電成像與噴墨成像數位印刷，印製PET 轉印薄膜後，再模內轉寫於被印材料的色彩品質特性；第二年實驗則以多種組合噴墨印製PET轉印膜，再模內轉寫於塑料射出基材上，透過嚴謹的實驗流程並量化的實驗量測與綜合分析，歸納出最適合的數位印刷方式以及轉印後最佳色彩品質特性組合。經研究分析可得如下結論：當覆蓋率與解析度愈高時，其滿版濃度愈高，在模內射出轉印至ABS材料後，各種組合的滿版濃度均呈現些微降低；有底色(白墨)模內轉印較符合一般印刷之階調擴增曲線；無底色(透明)模內轉印其印刷對比高於有底色之組合，換言之，無白墨之組合在暗部調表現優於有底色；在經過模內轉印至ABS材料上後，色彩色域都較轉印前來的小；有底色之組合較能滿足產品之色彩，而無底色其色彩偏移過大，主要還是因油墨經高溫之影響；經由整個製程分析，可以預測在此複雜的流程中，原稿階調至產品射出材階調間之變異。
Abstract
In Mold Roller (IMR) is a revolutionary printing process by which objects are 3-dimensionally decorated. The products decorated by In Mold Roller are protected from waterproof and fading. What’s more, these kinds of decorations strongly increase the beauty, desirability and value of the objects. As results of improved overall product texture, these commodities embody more beauty-attraction, publicity-oriented, and value-added features. The In-Mold Roller is now using either of gravure printing and screen printing to print PET film. However, there are some problems with these two techniques. This research is to investigate the potential use of combining In-Mold Roller with digital Electophotography and UV inkjet printing in 3D decoration, e.g. in personalized printing services. The study results found show that digital printing to the PET film and then transfer to the ABS, the solid ink densities (SIDs) of primaries would increase. When the coverage and the resolution by inkjet printing higher, the SID will be higher. When transfer to ABS, each combination of SID will decrease. The tone values increases (TVIs) with white ink were generally higher than those without white ink. The shapes and sizes of color gamut were also varied according to different kinds of digital UV inkjet printing processes. Compare to the IMR without white ink, the PC value are higher than the white ink. After transferred, the color gamut became smaller.