| 摘要 |
In a cationic electrocoating process in which phosphoric acid is used as an acidic ionizing agent for the polymer in the coating composition, and in which excess phosphoric acid build-up in the bath is removed by ultrafiltration, phosphoric acid in the filtrate can be reacted with certain metals to make dissolved dihydrogen metal phosphate salt so that the filtrate can be returned to the electrocoating bath. In the bath, part of the dihydrogen metal phosphate salt is consumed by its deposition on the substrate as an insoluble metal phosphate salt.
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