Abstract:
Due to environment concern the usage of oil based ink in printing industry has been
diminishing. Oil based ink contains very huge amount of volatile organic compounds
Water based ink can be used as an alternative. The purpose of water based is to reduce the
volatile organic compound from the ink. Water-based Flexo printing inks are very
sensitive to pH. These can be easily dissolved in water. Due to hydrophilic nature it can
easily be detached compare to solvent based ink. Pulping when done at higher pH we get
the very small ink particles are disperses in water and difficult to remove them in flotation
process. Flotation process works efficiently when ink particles size is bigger ranging
(>10) μm where as washing best suits for smaller ink particles (< 1 μm). Hydrophilic
particles favour the washing process whereas the hydrophobic particles are efficiently
removed by flotation. The resins used in water-based Flexo printing inks are soluble at
higher pH. They get easily dispersed in the medium and difficult to remove during
flotation because of particle size and hydrophilic surface. Difficulty in removing the
water based ink is the main motivation for optimising the flotation process for this type of
ink particles and tuned the parameters like pH, Temperature, Consistency for the flotation
process. So that ink particles get easily agglomerates and removed during the process.
The ink elimination is increases on decreasing the pH keeping the minimum chemical
needed for their function while temperature shows the direct relation with the ink
elimination. But the optimum range for the system temperature is from (40-50) ⁰ C for
the soap formation and so for ink removal
