The stability of offset inks on paper upon ageing
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English Slovak |
| ISSN: | 0143-7208 |
| Online Access: | http://www.viks.sk/chk/dyesandpig_2002.doc |
| Abstract: | SUMMARIES. The standard moist heat (80 °C and 65% relative humidity) and dry heat (105 °C) techniques of accelerated paper ageing were applied in stability investigations of offset ink films printed on alkaline offset paper. The measured characteristics of paper sample evidenced its first-class mechanical properties, large alkali reserve, in addition to high values of brightness and opacity. The pseudoplastic flow behaviour was established for original offset CMYK printing inks by rheological measurements. The results obtained, following application of both ageing procedures, revealed the significant exponential decrease of relative optical density for MAGENTA and YELLOW ink layers. The variance in visible reflectance spectra and in total colour difference E* (L*a*b* CIE) of ink films evidenced the considerable damage of CYAN and YELLOW ink films, especially upon moist heat treatment. The differences in lightness AL* play the dominant role in A* values of BLACK ink films upon both ageing procedures. The FT-IR spectroscopy was additionally used in the characterization of paper, inks, as well as ink films on paper before and after ageing. CONCLUSION. The moist heat (80 °C and 65% RH) and dry heat (105 °C) methods of accelerated ageing were applied in the stability investigations of CMYK ink films printed on alkaline offset paper. The exponential decline of paper brightness (paper yellowing) corresponding to the formal first-order kinetics was measured upon application of both ageing procedures, however only negligible changes were registered in the diffuse reflectance FT-IR spectra of aged paper samples. The highest variance of relative optical density during ageing was observed for the MAGENTA and the YELLOW ink films on paper. In contrast, the variations in visible reflectance spectra and in total colour difference AE* (L*a*b*) evidenced the considerable damage of the CYAN and the YELLOW ink films, especially upon moist heat treatment. |
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| ISSN: | 0143-7208 |
