1 1.2 Overview of Printing Technologies Ref. H. Kipphan, Handbook of Print Media: Technologies and Production Methods, Springer, 2001, sec 1.3, ch 2, ch 5

JCheng Overview of Printing Technologies Two classes of printing technologies Technologies requiring a printing plate Flexography, gravure, screen printing, micro- contact printing Technologies not requiring a printing plate Inkjet printing, laser printing

JCheng Letterpress/Flexographic Printing Characteristic of letterpress printing is The printing elements of the printing plate are raised above the non-printing elements Flexographic printing is a type of letterpress printing where printing plate is soft Printing can be done on rough surfaces & on fabrics ink splitting, fig fig

JCheng Letterpress/Flexographic Printing Questions Why anilox roller was introduced for inking the printing stamp? Can directly roll printing stamp through the ink tank do the job? Why the printing was done in the liquid phase, not in the solid phase? contd

JCheng Gravure Printing Characteristic of gravure printing is The image elements are engraved into the printing cylinder Schematic of gravure printing (fig )

JCheng Gravure Printing Questions Why the inking here is done through directly rolling over the ink tank? Why the printing is done in the liquid phase? contd

JCheng Lithography or Offset Printing Characteristic of lithography is The printing and non-printing areas of the printing plate are on the same level The printing areas are made “ ink-philic ” ( 親墨水 ) while the non-printing areas are “ ink-phobic ” ( 不親墨水 ). Lithography was invented by the end of 18th century (yr 1796) “ The image to be printed was drawn on the stone with a special liquid. The stone was dampened before it was inked up, after which the non-image areas of the stone surface did not take on ink. ”

JCheng Lithography or Offset Printing Schematic of lithography/offset printing (fig ) contd

JCheng Lithography or Offset Printing Ink transfer of offset printing (fig ) contd

JCheng Lithography or Offset Printing Questions How were the patterns created on the printing stamp at the first place? What is the purpose of the blanket roller? Why are multiple rollers used in the ink delivery subsystem? contd multiple rollers

JCheng Screen Printing “… a process in which ink is forced through a screen. ” Fig

JCheng Ink-Jet Printing Continuous vs. drop-on-demand ink-jet printing Fig

JCheng Micro-Contact Printing – Chemisorption A specially designed letterpress printing Proposed by Whitesides et al. in 1993 based on SAM (self assembled monolayer) technique (  CP)

JCheng Micro-Contact Printing – Chemisorption 2 steps of SAM process 1. Chemisorption of "head groups" onto a substrate 2. Self organization of "tail groups" contd Schematic of self-assembly mechanism for alkanethiols on Au(111). (A) Thiols adopt the highly mobile lattice-gas phase at very low coverage. (B) Above a critical value of surface coverage, striped phase islands, characterized by surface-aligned molecular axes, nucleate heterogeneously and grow in equilibrium with a constant-pressure lattice gas. (C) Surface reaches saturation coverage of striped phase. (D) Surface undergoes lateral-pressure-reduced solid- solid phase transition by nucleation of high-density islands at striped-phase domain boundaries. (E) High density islands grow at the expense of the striped phase until the surface reaches saturation. G. E. Poirier and E. D. Pylant, “The self-assembly mechanism of alkanethiols on Au(111),” Science 272 (1996)

JCheng Micro-Contact Printing – Chemisorption Two classes of SAM: thiol-based and silane-based contd Sven.Koehler/media/index.html thiol-based SAMsilane-based SAM bio1.shtml

JCheng Micro-Contact Printing – Physisorption Deficiency of chemisorption  CP Applications limited by few choices of SAM pairs of molecule and substrate Physisorption  CP exploiting physical adsorption, for example through van der Waals interaction Source: 呂冠毅, 中正大學機械所碩士論文, 2010