This study focused on ink transfer media for the lithographic print process. Rubber blanket is the offset media for ink transfer from plate to substrate. Performance of the rubber blanket is important for successful image reproduction. Thus, this ', project intended to develop a blanket for the lithographic print process that has good sheet release, good ink release, good dot reproduction, good solid reproduction (no pin-holing) and low swelling. The blanket should also maintain its compressibility and be capable of running metallic inks, UV inks· and conventional inks with no significant detrimental effect to the printing surface. Various surface layer compounds for a lithographic print blanket were formulated, with the aid of Minitab, and blankets were made according to the designed formulations. Evaluation work on the blankets for hardness, solvent resistance, critical surface tension, ink transfer, durability and quality of print was then carried out. Consequently, correlations of these characteristics with each blanket material component were studied. It was found that the hardness and the durability of the blanket were influenced by the content of the crosslinking agent and the reinforcing agent within the rubber compound. The solvent resistance and the ink transfer of a 'blanket were influenced by the content of nitrile within the rubber compound. The critical surface tension could be controlled by the change of speed of compound drying and the ingredients or by surface treatment. Following the studies carried, a blanket having significantly improved performance properties was developed. Also, interactions between blanket wash solvents and surface layer' rubber of blanket were studied with the help of FT-IR and GC-MS. It was found that solvent penetration into the surface rubber of a blanket, upon prolonged contact, was the main cause for blanket swell. Plasticisers were easily extracted from the surface rubber of a blanket by the blanket wash solvent, which resulted in a c:1taD&e I()i performance.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:485639 |
| Date | January 2008 |
| Creators | Sun, Changlong |
| Publisher | University of Leeds |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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