In purpose to observe the mechanism of the electrodeposition of the water soluble resins, some resins were prepared from ethylene-glycol and phthalic anhydride and were electro-deposited under different conditions. The following experimental results were obtained. (1) There are an approximately fixed relationship between the dry weight of the deposited resin and the number of coulomb of electricity passed, and the dry weight of the deposited resin per Faraday varies with the condition of the electrodeposition. (2) The quantity of the iron in the deposited resin is by far smaller in this experiment than that which should be expected to be contained in the deposited resin, if the polyester resin is deposited by Ferric ion mechanism. (3) The deposited resin is easily resoluble in the solution, from which it is deposited. (4) Some relationship exists between the dry weight of the deposited resin per Faraday and the carboxy-ic acid equivalent weight, which is equal to the weight of the resin, carried by the equivalent weight of carboxylic group. From the above experimental results, authors suppose that the following ionic reaction is the major reaction of the electro-deposition of the resins.
α-Fe2O3 (cubic shape) was prepared by hydrothermal treatment of ferric hydroxide, and could have various particle size from 30 mμ to 10μ by the variation of the treatment condition i.e. temperature, time, and pH of mother liquor. The relation between particle size and pigmentary properties of these samples was studied. As a result, the sample showed maximum value in both hiding power and tinting strength at particle size about 300 mμ. The hiding power of the sample was determined by an application of Kubelka-Munk equation. The scattering coefficient S of the sample required for above calculation was obtained by mixing with a known amount of standard pigment whose absorption coefficient K and scattering coefficient S were known. The K and S of the standard pigment (granular ZnO) were evaluated by measuring the reflectivity and the reflectance of the pigment layer of known thickness over a black substrate. The tinting strength of the sample was expressed as the color difference that is the distance of the tint with white pigment from the origin in a uniform color space, since tinting strength of colored pigment is defined as the property hard to become whitish when it is mixed with white pigment.