Electrodeposition paints, pigmented

Electrodeposition. Electrodeposition paints are suspensions of binders and pigments in fully demineralized water with low concentrations (ca. 3 %) of organic solvents (see Section 3.8). Electrodeposition coating may be either anodic or cathodic. 

One of the main differences of electrodeposition paints with conventional water soluble paints is their lower solids and thus solvent content. A typical binder content is around 10%w, the amount of solvent approximately 5%. The rest, apart from pigmentation, is water. The influence of solvent in the early stages of binder/paint formulation is very similar to the effects described for conventional aqueous paints which is also started from an approx. 70% solids binder solution in coupling solvent(s). The choice of the solvent (blend) is, however, less influenced by its evaporation characteristics as the deposited paint film does not contain much water and is stoved after application. Of more importance are paint stability and electrical properties (conductivity, rupture voltage). 

There are a number of excellent books on paint formulation and this chapter is not the place to go into detail on such a complex subject. The basic principles of formulating electrodeposition paints are the same as used in formulating any other paint, but the parameters such as pigment volume concentration tend to be somewhat different from those of dipping and spraying paints. 

The paint formulator has additional latitude in the choice of resins because dispersed macroions can be used as emulsifying agents for a variety of resins. These, as well as many pigments, will electrodeposit together with the macroions. 

The binder properties are useful in other pigmented coatings such as clay-based paints (119). The zinc-lithium silicate coatings can be applied by anodic electrodeposition on steel (120). In another-typc of use, lithium polysilicate provides an intermediate bond between the fluorocarbon polymer coating and metal on antisticking cook ware (121). 

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