Classification effect and dispersion performance of a three-roll mill were investigated with a simulation model and experiments. The simulation model was derived by extending the simulation model of two-roll mill to three-roll mill. In the experiment, fly ash and chalk were used as pigments and linseed oil varnish as vehicle. Premixed mill base was milled by a three-roll mill and grind gauge value of the dispersed sample was measured. The data of scraped sample density and degree of classification in our previous work were also used in this paper.
The changes of scraped sample density and the degree of classification were well represented by the simulation. The ratios of grind gauge value after dispersion to that before dispersion were well correlated by the ratio of minimum nip clearance to grind gauge value before dispersion with a single curve independently of particle size level and particle volume fraction. This behaviour was well represented by the simulation.

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The experiments were carried out to reveal the measuring mechanism of the pencil hardness test. At first, the correlation was examined between Vickers hardness (Hv) of the leads of the pencils and the hardness designation for their pencils. Secondly, making the alloy mixed in various ratios with tin and lead or zinc on an experimental basis as the sample for the lead of a pencil, the scratch tests and the mechanical properties were measured on the various kinds of coatings having the different grades of hardness, and the relation between them was discussed. Main results were as follows : 1) The correlation was observed on the inspected pencils between Hv of the leads and the hardness designation. 2) There was not a clear relation for the coatings between the scratch hardness and Hv or modulus. 3) Comparing the two kinds of the leads, in the case of the alloy lead a good relation was observed between the scratch hardness of the coatings and their tensile strength, but this relation was poor in the pencil lead. 4) The value of Hv of the alloy, which showed the scratch hardness of the coatings, was usually larger than that of the pencils. It can be considered that this result is caused by the difference in the physical properties of the leads, that is, the pencil indicates brittle fracture, whereas the alloy indicates plastic deformation.

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Low temperature plasma treatment of carbon black was carried out by using dinitrogen oxide which easily release the atomic oxygen, or plasma activated oxygen in order to obtain informations about the mechanism of plasma oxidation. The influence of mercury vapor from MacLeod gauge on plasma treatment was also investigated.
The treating conditions such as the formation of oxygen active species depressed and the reaction of oxygen and radical active site formed on the sample surface increased were desirable to make a sample with good dispersion state property in water. The former conclusion that the plasma oxidization reaction of carbon black preferentially proceeded as radical auto-oxidization was supported by these results. It was found that the mercury vapor captures the atomic oxygen and has the action of depressing the decomposition of sample.

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Conventionally, about 1 PHR of titanium white is mixed in the chromatic coating of polyvinyl chloride resin for tone enhancement reasons. This small amount poses the problem of poor weatherability. This paper deals with the paint and coating characteristics of paints with fine-grain titanium dioxide added for the purpose of maintaining the chromatic color tone and improving the weatherability of the coating.
It has been found that by the use of as much as 5 PHR of fine-grain titanium dioxide, it is possible to obtain the same tone as for a mixture containing 1 PHR of titanium white, without posing any practical problems paint or coating characteristics. Authors have also found that with the coating containing 5 PHR of fine-grain titanium dioxide the decomposition of the polyvinyl chloride resin by ultraviolet rays is retarded more than for the coating containing 1 PHR of titanium white, and discoloring is less apparent, resulting in a paint with excellent weatherability.

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Various wet digestion methods were examined each other for the determination of copper, zinc and tin in antifouling paints (A/F). The recommended procedure was as follows. A sample (about O.5g) was gently heated in a mixture of 30 ml hydrochloric acid and 10 ml nitric acid. After decomposition, the resulted solution was filtered through Toyo-5 B filter paper and diluted to 100 ml with 1 M-hydrochloric acid. Concentration of copper, zinc and tin were then determined directly on the solution by atomic absorption spectrometry. The atomic absorption of tin was measured by air-hydrogen fuel-rich flame, though copper and zinc were measured by conventional air-acetylene fuel-lean flame. This method was applied to the determination of copper, zinc and tin in antifouling paints (n=10) and the results obtained were in good agreement with theoretical values. The relative standard deviations (RSD) of copper, zinc and tin were less than 2%.

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