1967 年 23 巻 6 号 p. 407-414
A blend prepared by milling carbon black and a resin in a ball mill for about 300 hours is used as a paint in printing resistance elements on the miniature electronic circuit. Experimental results on the use of ultrasonic blending in place of the conventional ball mill blending in manufacture of this paint are reported in this paper. The auther classified the phenomena occurring during the blending process into the following three in discussion of the results. a)Pulverization of carbon black Fig. 2 to Fig. 4 are the photographs of carbon black in resin mixed during 2, 120 and 650 hours, respectively. In Fig. 4, particles of 10 microns remain after milling even for 650 hours. The photographs from Fig. 5 to Fig. 7 are results of treatment by ultrasonics for 2, 10 and 30 minutes. Fig. 7 shows the particles pulverized uniformly into a few microns. It proves that the ultrasonic method can disperse carbon black into the resin in a shorter time and better than the ball mill method. Fig. 8 is the graphs of milling time versus resistance value mixed by a ball mill and by a ultrasonics, and the results of treatment by ultrasonics indicate a decrease in the resistance value in a shorter time. b)Depolymerization of the resin Fig. 9 is the curves of milling time versus degradation of DC-996(silicone resin) by a ball mill and by ultrasonics. The viscosity of resin becomes lower in a shorter by ultrasonic method than by a ball mill. Table 1 shows the viscosity change of the various resins treated during 30 minutes by ultrasonics. The most suitable resin(DC-996) for paint recommended by B. L. Davis depolymerize most readily, as well as KR-272. c)Dispersion of carbon black Fig. 10(carbon black in ethyl alcohol), Fig. 11(carbon black in low viscosity resin), Fig. 12(carbon black in high viscosity resin), and Fig. 13(carbon black and inorganic matter in low viscosity resin) are the results of dispersion by the ultrasonic method respectivety. As indicated by the results, the degree of dispersion depends upon the solution, viscosity of resin and the amount of added inorganic matter. In Fig. 14 in which inorganic has been added, resistance becomes smaller with treatment time by ultrasonics.