Impact of extenders in TiO2 reduction and curing efficiency in UV cured flexo ink

 
The use of ultraviolet light to cure inks in the packaging printing industry has become more and more common since it has been first developed. Indeed, the need for more visual appeal in packaging, with quicker curing rates and lower waste, has been one of the drivers behind this growth. TiO2 is the most commonly used pigment in white UV cured flexo ink due to its high refractive index providing high opacity even at thin film thickness. Unfortunately TiO2 absorbs in the UV spectrum and as a detrimental effect on the curing of the ink. In addition a high loading of TiO2 can be detrimental for the optical performance due to crowding of particles. This paper reports how kaolin and calcium carbonates can substitute a part of TiO2 in UV-cured flexo inks whilst still maintain a high gloss and suitable opacity. In addition the impact on the curing efficiency has been evaluated.