Abstract
Quantitative analysis of acid and base groups contained in a resin solution for an electropaint system is important parameters to analyze characteristics of the resin solution. Analysis is generally performed with potentiometric titration after dissolving the resin solution into a tetrahydrofuran (THF) solvent. Researchers have empirically understood that the measurements involved in analysis include a certain amount of analytical errors. This study investigated the influence of water-THF used as a solvent on quantitative analysis for acid and base groups in an electrodepositable resin solution in order to minimize analytical errors.
THF is more basic than water and produces no leveling effect on a strong base as a solute. Thus, only a blank test for KOH titration produced a blank value, but the blank test for HCl titration yielded no blank value. Results indicated that the blank values obtained from the blank test of KOH titration depended on relative dielectric constant of the solvent used for the titration. Adjustment of the relative dielectric constant to 20 to 40 by mixing THF with water minimizes the blank value.
