Rheological measurements of cure rate of UV inks

✍ Scribed by Yasufumi Otsubo; Takeshi Amari; Koichiro Watanabe

• Publisher: John Wiley and Sons
• Year: 1986
• Tongue: English
• Weight: 527 KB
• Volume: 31
• Category: Article
• ISSN: 0021-8995
• DOI: 10.1002/app.1986.070310713

✦ Synopsis

The dynamic viscosity of UV inks during curing was measured at various film thicknesses using a n oscillating plate rheometer. Logarithmic plots of the dynamic viscosity versus exposure energy are closely related by two.straight lines. A useful concept in discussing the curability is the minimum exposure energy defined as the exposure energy at the intersection of two lines. On exposure to a monochromatic light of 365 nm, the minimum exposure energy increases exponentially with film thickness; this resulting from a n exponential decay of the light intensity with depth in the film. Magenta ink shows the fastest cure rate at a given thickness, followed by yellow, cyan, and black inks in that order. The difference in cure rate is attributed to different absorbances of pigments. The UV curability on direct exposure to UV lamp is predicted from the spectral sensitivity of the photoinitiator and the viscosity data obtained during curing under 365 nm light. The model calculation shows good agreement with the experimental results.