Abstract JIAJUN, LIU. Ink Limiting and Its Impact On
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Abstract JIAJUN, LIU. Ink Limiting and its Impact on Color Quality of Inkjet Printed Cotton Substrates (Under the direction of Dr. Lisa Parrillo-Chapman and Dr. Renzo Shamey). Digital printing is increasingly considered an important process in reproduction of colored substrates in the textile sector. Compared to conventional printing technologies, the advantages of digital textile printing include quick reaction time, short run capability, low waste production, high image resolution, and improved color rendering, among others. Inkjet printing technology was originally invented for paper printing, and standards and evaluation procedures are well established in this sector. To reduce ink consumption and make the production and reproduction process more sustainable and viable at a lower cost, the concept of reducing ink limiting levels was introduced. While several patents and papers about ink limiting in paper printing have been published over the last twenty years (Hewlett-Packard,1997; Zeng, 2001; Urban, 2009; Shestak, 2009; Qiao, 2012; Kirkenaer, 2013), very little research has been conducted on ink limiting for textiles. However, characteristics and application of textile fabrics are significantly different from paper media. For example, it is important to have good color fastness properties in textile printing, while this might be less important in paper printing. Color reproduction techniques in textile printing are also somewhat different from those used in paper printing. Thus, in textile printing, it is not suitable to utilize the current testing image and evaluation methods which are designed for, and used, in paper printing. A significant amount of research has been done to improve the print quality in textiles. In addition, color reproduction fidelity has been evaluated by examining various parameters such as line width, dot shape, uniformity and characteristics of prints with solid colors, as well as color mapping for transitions required between different devices, such as from digital media to printing machines. The two evaluation approaches commonly adopted in the textile printing industry are the subjective and objective methods. Subjective evaluation is easy to manipulate but it is highly dependent on the testing image. Objective approaches are more repeatable, but there are too many metrics to test, and the overall evaluation results will be dependent on the selection of metrics. Nonetheless, evaluation of colors in a multi-colored item is still primarily done in a subjective manner and an agreed upon standard assessment protocol is not yet available. To address these two major challenges, this research aimed to investigate the influence of ink limiting on digital printed cotton substrates and develop a quality evaluation procedure for the digital textile printing process. The research included three objectives. Objective One was to develop a workflow and a cause-effect diagram to improve the understanding of ink limiting, ink limiting adjustment, and factors that affect print quality. Objective Two was to develop a quality evaluation method to investigate the impact of ink limiting on print quality. Objective Three was to create a testing image for ink limiting optimization. © Copyright 2020 by Jiajun Liu All Rights Reserved Ink Limiting and its Impact on Color Quality of Inkjet Printed Cotton Substrates by Jiajun Liu A dissertation submitted to the Graduate Faculty of North Carolina State University in partial fulfillment of the requirements for the degree of Doctor of Philosophy Textile Technology Management Raleigh, North Carolina 2020 APPROVED BY: _______________________________ _______________________________ Dr. Lisa Parrillo-Chapman Dr. Renzo Shamey Committee Co-Chair Committee Co-Chair _______________________________ _______________________________ Dr. Harold S. Freeman Dr. A. Blanton Godfrey Dedication To my family and friends ii Biography Jiajun Liu was born in China and moved to U.S. to pursue her Ph.D. degree in 2016. She obtained a Bachelor’s degree in 2012 in physics at Hubei Normal University and worked as a high school physics teacher for a year. She decided to pursue her passion in apparels and obtained a Masters’ degree in Fashion Design and Engineering at Wuhan Textile University. While doing her masters, she also ran her own boutique and T-shirt printing business. Her research at NC State focused on various topics pertaining to digital textile printing. She has built her expertise in color management and obtained a number of certificates in printing and color management. In her spare time, she loves painting, drawing, sewing, cooking, and gardening. iii Acknowledgements My journey through this Ph.D. program was one of the toughest journeys I have ever had. It was full of stress, laughs, tears, with many nights of reading, writing, and working in the labs. I could not go through it without the tremendous care and help that I received from people around me. I would like to take this opportunity to thank my advisors, Dr. Lisa Chapman and Dr. Renzo Shamey, for their support, guidance, and patience. I could not express how much I have learnt from them; working with them was a wonderful experience and it will be a remarkable milestone in my professional career. I would also like to thank my committee members Dr. Blanton Godfrey and Dr. Harold Freeman for their valuable comments and suggestions. I thank Dr. Joel Trussell for his advice and suggestions and taking time to meet with me in the college. I thank Dr. Christopher Healey for accepting the role of the GSR and for his time and availability. I wish to express my appreciation to TTM faculty and staff. I thank Dr. Abdel-Fattah Seyam, Dr. Marguerite Moore, and Dr. Rothenberg for their wonderful classes. I also thank Dr. Yingjiao Xu for her support and advice. I express my gratitude to Mr. Tri Vu for his help in various operations and I thank Mr. Mark Sawchak for his help in creating useful industry connections. I also want to thank my colleagues and friends. I thank all the members from the color science and imaging lab as well as the digital printing group. I appreciated the weekly seminars in the color science lab and enjoyed the interaction and exchange with my peers. I am grateful to my friends Nimet, Jennifer and TTM officemates for their friendship. Last but not least, I am indebted to my parents, Cuiguang Liu and Lihong Yin, without whose trust and support this journey would not have been possible. iv Table of Contents List of Figures .............................................................................................................................. viii List of Tables ................................................................................................................................ xii Chapter 1. Introduction ................................................................................................................... 1 1.1. Background to the Problem ............................................................................................... 1 1.2. Research Objectives ........................................................................................................... 4 1.3. Research Relevance ........................................................................................................... 5 Chapter 2. Literature Review .......................................................................................................... 6 2.1. Inkjet Textile Printing Technology .................................................................................... 6 2.1.1. Inkjet Print head ...................................................................................................... 7 2.1.1.1. Continuous Inkjet Printing ............................................................................... 9 2.1.1.2. DOD Inkjet Printing ....................................................................................... 10 2.1.2. Print Mode ............................................................................................................. 12 2.1.2.1. Multi-pass versus Single-pass Printing Multi-pass Printing .......................... 12 2.1.2.2. Binary versus Greyscale Printing mode ......................................................... 13 2.1.2.3. Multi-Channel Printing .................................................................................. 15 2.1.3. Digital Halftone Image .......................................................................................... 18 2.1.3.1. Halftone Pattern ............................................................................................. 18 2.1.3.2. AM and FM Halftone Techniques ................................................................. 19 2.2. Ink and Substrate.............................................................................................................. 21 2.2.1. Ink Physical Properties .......................................................................................... 21 2.2.2. Ink Classification ................................................................................................... 23 2.2.2.1. Molecular Formation of Color ....................................................................... 24 2.2.2.2. Color Index Generic Name ............................................................................ 26 2.2.2.3. Dye-based Inks............................................................................................... 27 2.2.2.4. Pigment-based Inks .......................................................................................