Electrodeposition Coating Process for Automobile Bodies

The earlier electrodeposition process was mainly pursuited for the quality control in terms of mass production. However, the coating efficiency was picked up to be a serial problem from a standpoint of the harmony between natural circumstances and human's living-life conditions and the recovery usage of the paint was earnestly searched. This trend led to the development in various technical fields. The second impetus on further improvement of electrodeposition paint was due to oil crisis in 1973. The new technology relating to save-energy was developed. In the paint industries, the further improved anti-corrosive performance was strongly demanded. This demand also involved the development of new materials for automobile bodies and even the design of bodies structure. In this report, the introduction of electrodeposition process into automobile industries in Japan is hystrically reviewed and the electrodeposition mechanism and the mechanism which deposited materials from the coating film are briefly explained. As the demand for anti-corrosive performance is increased, the coating system in which the anodic oxidation and the dissolution from the object metal can not occur, was aimed and recently it was rapidly accepted as the superior system. On the other hand, there is an opposite opinion for this trend on the basis of the metal analysis detected in the deposited film. The characteristics of cationic electrodeposition, in particular, the superior corrosion resistance with regard to the metal dissolution in the whole electrodeposition process is explained. In Chapter III, throwing power which is characteristic for electrodeposition process is described. It is referred that throwing power is not necessarily determined by the paint performance. Even the electrodeposition coating system, the areas into which the paint liquid does not intrude can not be coated. And it is pointed out that the design of bodies structure is inevitably necessary as well as the improvement of paint performances. In Chapter IV, the role of the main component, vehicle resin, is introduced. The devices which disperse resin into solvent 'water', and factors which determine the polarity of electrodeposition are explained. And the typical resin structure is shown. The paint performance is greatly effected by the vehicle resin, but it is also deeply related how the paint is produced and how it is coated. Therefore, it is inferred that the paint performances are relatively estimated. In Chap