OPTIMIZING STARCH LATEX BALANCE IN COATING COLOR TO GET COST EFFECTIVE FORMULATION

Abstract

The study planned in this present investigation mainly focuses on the variation of properties of coated paper with varying composition of coating color in which only binders are changed. Styrene butadiene latex and starch are being used in the paper industry as binders, either in combination or alone. The cost of SB latex is higher (approximately 3 times more) than that of starch depending upon the composition of SB latex and starch and their characteristics. However the use of starch and latex proportions in the binder are governed by the desired properties of paper. The work focuses on the investigation of coating color composed of Calcium carbonate, clay, SB latex and starch on writing printing grade of nearly 60 gsm. The starch supplied by M/S Hindustan Lever Limited, Bio polymer division, Pondicherry is of three types, A, B, and C. First set of experiments include the study of latex as a sole binder and then with combination starch samples on the same quality of paper. For all the experiments with starch, thei proportions of latex as well as starch A, B and C are made to vary keeping in mind that the relative binding power of Latex to starch is 1.5. In other words, the ratio of latex to starch has been ,kept constant in all experiments. The experiments are run in "DT Paper science Finland" laboratory coater recently procured by CPPRI, Saharanpur. Styrene Butadiene shows increase in IGT, gloss, opacity, smoothness, brightness and whiteness with the increase in amount of SB latex in the binder, whereas porosity is found to decrease as the very small sized plastic particles of SB latex increase in the coating formulation. The mixture of latex and starch however has shown, in most of the cases, opposite trend except MT. However all starch samples supplied by the Hindustan Lever Ltd. show a similar nature of effect on properties of coated sheets. As the amount of starch in the coating color increases, the IGT value and the porosity are found to increase. But the opacity, gloss, smoothness, brightness and whiteness properties decrease with the increase in amount of starch in binder level in coating color formUlation. The data of experiments show that the starch sample A is better than B and C. As a matter of fact, in order to select the cost effective binder if starch at all to be used, series of regression equation in polynomial form (to get R2. value nearly equal to 1.0) ++ have been formulated from Microoft Excel software. These equations are fitted to C+