Optical measurements of painted surfaces by Schlieren method were studied. As a result the relationship between the distribution function of surface slope and image clearness was made clear. There have been some attempts to realize the relation between the surface roughness and image clearness, but they have not been successful so far. In this study, surface roughness was measured and expressed by means of the slope which is the function of the position on the surface. It was found that the image clearness calculated from the slope distribution functions was in good agreement with that measured directly.
The effect of grafting two kinds of silicones on the dispersion stability of TiO2 particles coated with SiO2 in poly (dimethylsiloxane) was investigated. One is a poly (dimethylsiloxane) derivative carrying a trimethoxysilyl group at one terminus (A), and the other is one having a trimethoxysilyl group at one terminus and a trimethylsilyl ester group at the other terminus (B). The amount of the polymer immobilized on the particle surface was determined by the diffuse reflectance FT-IR measurements. The amount of the grafted polymer on the particles treated with B was ca. 4. 6 times greater than that treated with A at the reaction temperature of 200°C. From the time dependence of the turbidity and the direct observation of the particles by an optical microscope, the dispersion stability of the particles treated with B was found to be better than that of the particles treated with A. The better dispersion stability of the former was ascribable to two kinds of the endcapping effects due to the trimethylsilanol generated by the hydrolysis of B. The first is due to an increase in the entropic repulsion and a decrease in van der Waals attraction force, which result from the increase of the amount of the grafted polymers. The conformation change of the grafted polymers accompanied by the decrease of the interaction between the particle surface and the siloxane chain of the grafted polymer is suggested to be responsible for it (intraparticle endcapping effect). The second is due to a decrease in the bridge formation between the particles caused by the adsorption of the grafted polymers (interparticle endcapping effect).
We inspected the relation between coating factors and coating efficiency in air-atomizing electrostatic coating on a square post under the experiment-scheming method. Then we obtained following results. ·Factors which influence deposition property are electroresistance of paint, work size, interval of work, spray distance, paint flow rate, pattern air pressure and electrostatic voltage. Factors which do not influence deposition property seriously are temperature, humidity, paint viscosity, type of solvent, gun speed and atomizing air pressure. ·Factors which influence the atomization are not influential very much against deposition property. ·The factors which are thought to be important for the expansion of the pattern influence deposition property deeply. Therefore, we consider that the deposition property is influenced by sprinkling condition in the space.