Improving Resistivity of Resin

Resistivity of resin plays a vital role for trouble free performance of electrostatic application of resin based paints. Low resistivity results in electrical shorting and high resistivity leads to poor deposition of paints due to insufficient charge pick up. Hence resin resistivity should be maintained within a specified range. The present study was undertaken in a reputed paints manufacturing enterprise. The concerned firm was not able to maintain the resistivity value within the desired specification. They were consistently getting low resistivity. It was decided to study on identifying significant factors for controlling resistivity through experimentation.A 23 full factorial experiment was conducted with three factors phthalic anhydride%, water collection time, and solvent distillate collection time, each varying at two levels. The experiment could not be replicated due to time constraint. After analysing the data, using Bayesian method of posterior probability plot the main effect of water collection time and solvent distillate collection time were found to be significant at 5% level of significance. Considering expected values of resistivity at different levels of significant factors, optimum levels were arrived at so as to achieve the expected average resistivity value closed to the target value. Taking experimental error into account a 95% confidence interval was obtained which was lying within the desired specification. Confirmatory trials were made for few batches. Since the results of confirmatory trials were satisfactory the recommendations were accepted by plant management. As a result of implementation of the recommendations of the present study the concerned firm was able to get the value of resin resistivity within the specification.