Standardizing milling process parameters for the narrowest pigment particle size distribution with optimum energy consumption DOI 10.14622/JPMTR-2007

Abstract

Water-based ink, used in production of a new type of green packaging material has an efficient application in the flexible packaging industry to resolve the environmental issues related to volatile organic compound. To get the best possible application properties of dispersed pigment whose performance is mainly measured by the particle size distribution, it is essential to reduce the size of agglomerates. Concentrated dispersed material is manufactured by using a stirred bead mill, which is an energy-intensive process. The process of dispersion must be done efficiently and in the shortest possible time to draw out of the pigment its maximum color properties at the minimum cost. The grinding-energy efficiency is a significant parameter in bead milling as that affects the amount of energy used during grinding of pigment particles. The milling process needs to be optimized to reduce energy consumption. The objective of this study is to determine optimum dispersion process parameters to optimize energy consumption to achieve the narrowest pigment particle size distribution of rubine red pigments used in water-based ink. Experiments were conducted for fine grinding of organic rubine red pigment using a vertical bead mill. The experiments were conducted for varying sizes of grinding media from 0.5 mm to 1.0 mm, for two pigment
loadings of 30 % and 37 %, and by extending milling time from 4 h to 6 h. The pigment particle size distribution and power consumption during each trial were measured to optimize process parameters with minimum energy consumption. Response surface design was performed to analyze data. Analysis of variance (ANOVA) techniques were used to check the significance of factors and the interaction of factors. The regression model for specific energy consumption was developed and tested; validation trial for dispersion process parameters concludes that 30 % pigment loading and mixed grinding media size provides narrowest pigment particle size distribution of 128 nm with minimum energy consumption of 1.67 kWh/t.