Asst. Prof. Dr. Juntira Komasatitaya, (Material Engineering), Lecturer and printing ink researcher, King Mongkut’s University of Technology Thonburi, Thailand.
Study of Starch and Polyvinyl Alcohol Blended Vehicle for Biodegradable Printing Ink in Flexography
Juntira Komasatitaya, Kritsanapong Tangprajakpakdee, Phongsit Attapornpimol, and Supanee Boonyatassaneekul, King Mongkut’s University of Technology Thonburi
In this present work, we have studied ink formulations of cassava, rice, and corn starches blended with polyvinyl alcohol as binder for water based flexographic ink printing which aimed to compare the printing inks made from these three starches. Cyan flexographic printing inks, which was a corrugated board printing formulation were prepared and mixing with starch-blended-Polyvinyl alcohol,1:1, 1:2 and 2:1. It was found that the ratio of 1:1 gave good miscible blending without phase separation of starch-blended-Polyvinyl alcohols in the water based vehicle of the flexographic printing ink. The experimental results showed that the cassava starch ink had the highest viscosity of 5634-13800 mPas, whereas the corn starch ink had the lowest viscosity approximately 3468-9660 mPas. The rice starch ink had the greatest print density of 1.13, and the color print showed the high test lightfastness compared to the other starch inks. All of the starch blended inks had a good level rating scale of rub resistance. The flexographic printing ink made from the cassava starch showed the result of the highest water resistance,comparatively, as it was re-dissolved in the water for 5.17%. The rub resistance improvement of the cassava ink with melamine cross-linking agent did not give satisfying results as well as some ink properties were unfortunately altered such as viscosity, water resistance.
Figure1: Viscosity dependency of water flexo printing inks of cassava (blue), rice (magenta) and corn starches (red)