Regarding to the cratering in paint films, an investigation was made in connection with the effect of the physico-chemical properties of silicone oils added to the paint for preventing the flooding, and results were obtained as follows. 1) Craters appear in all cases where paints containing silicone oils in an amount exceeding their solubility limit are used. 2) There is a close correlation between the tendency of cratering and the condition of the silicone oils dispersed in paints as particles. Craters appears without exception in cases where the radius of the particles exceeds a critical value determined depending on the nature of the paint and coating film thickness. 3) Stirring of the paint gives an impetus to the growth of the silicone oil particles. Refering to the above results, it is concluded that the silicone oil added to the paint should be soluble perfectly, otherwise it may become the origin of the craters in coating films.
Antifouling polymers were synthesized by adducting the toxicants of several combinations of phenarsazine chloride, pentachlorophenol, trichlorophenol, tributhyltinhydroxide, 1-hydroxyimidazoles and 1-hydroxyimidazole-3-oxides to the polyacrylchloride. The antifouling properties which were evaluated by mortality of pond snails were thus compared with those of the physical mixtures of the antifouling polymers consisting with mono toxicants. The results revealed that the mutual interactions of toxicants brought better antifouling properties. In particular, this was remarkable in the case that each toxicants in the polymer had chemically different constituent. Moreover, the antifouling properties of the polymers possessing multi-toxicants were better than those of polymers consisting with physical mixtures.