Removal of organic solvent from cathodic electrophoretic emulsion paint by vacuum steam stripping

QIU Yun-ren(邱运仁), LI Xiao(黎晓), WU Ding-yu(吴定宇)

(Key Laboratory of Resources Chemistry of Nonferrous Metals of Ministry of Education
(School of Chemistry and Chemical Engineering, Central South University), Changsha 410083, China)

Abstract:The production of environmental friendly emulsion paint is of great significance. Vacuum steam stripping of methyl isobutyl ketone (MIBK) and methyl ethyl ketone (MEK) from cathodic electrophoretic emulsion was studied. The effects of mass ratio of vapor to feed (V/F), vacuum degree and feed temperature on removal rate of MIBK and MEK, emulsion size and solid volume fraction of the emulsion were investigated, and the removal of MIBK and MEK from cathodic electrophoretic emulsion by vacuum desorption was also studied. The results show that removal rates of both MIBK and MEK increase with the increase of V/F, vacuum degree and feed temperature. Removal rates of MIBK and MEK are 98.3% and 93.6%, respectively, at the operating condition V/F of 0.7, feed temperature of 27 °C and vacuum degree of 90 kPa. The emulsion size of cathodic electrophoretic emulsion increases slightly with feed temperature when temperature is below 42 °C, and increases rapidly with feed temperature when temperature is above 42 °C. Solid volume fraction increases by 10% as vacuum degree increases from 0 to 90 kPa at V/F of 0.7 and feed temperature of 27 °C. Compared with vacuum desorption, vacuum steam stripping can get a higher removal rate of MIBK and MEK under the same feed flow, vacuum degree and feed temperature.

Key words:vacuum steam stripping; environment friendly emulsion paint; waterborne coating; methyl isobutyl ketone; methyl ethyl ketone