engleski

Lightfastness of some flexographic prints

In this paper the lightfastness of flexographic prints was studied. Studied prints were obtained using conventional solvent based and UV curing flexographic inks. The prints were made on polypropylene(PP) and polyvinyl chloride (PVC) foils. Applied polymer substrates were treated with Corona process before printing and their surface energy was tested with testing pen. Flexographic printing is frequently used for polymer packaging products and the lightfastness of obtained prints is extremely important. Low lightfastness prints are changing and/or loosing colors. Such prints have negative effect for sellers of various goods packed in polymer package. It is well known that numerous flexographic prints on polymer substrate are often placed on the shelves in the market were these prints are more or less exposed to sunlight and the only protection are windows. The lightfastness of prints is an ability to retain its color strength and resist fading upon exposure to light (sunlight or light from numerous sources). According to ISO 12040 studied prints were exposed to light from Xenon lamp only and to the combination of light from Xenon lamp with artificial rain during 72 hours. The experiments were carried out in prints area in fulltone and halftone patterns, as well as in overprint patterns. Analyzes of lightfastness was established according to Blue Wool Scale.

flexographic printing; lightfastness; PP; PVC; solvent based ink; UV ink

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