Journal of the Japan Society of Colour Material
Online ISSN : 1883-2199
Print ISSN : 0010-180X
ISSN-L : 0010-180X
Volume 57, Issue 12
Displaying 1-4 of 4 articles from this issue
  • Yasuhiro MURAKAMI, Gishi CHUNG, Kyoji KAWAGUCHI, Tsutomu HIROSE, Yuji ...
    1984 Volume 57 Issue 12 Pages 635-642
    Published: December 20, 1984
    Released on J-STAGE: November 20, 2012
    JOURNAL FREE ACCESS
    The classification effect in a roll nip of a three-roll mill was investigated with a simulation model and experiment. In the experiment, fly ash was used as pigment and linseed oil varnish as vehicle. Premixed mill base of density, ρ0 which was supplied between feed and center rolls was scraped off from apron roll at n times by sampling weights of 1/n of total weight. The densities, ρc and particle size distributions of these samples were measured. The experiment was carried out with various particle weight fraction, φw0, particle size level and viscosities of vehicle.
    The following results were found from the simulation and experiment. At the beginning, samples of low density, having fine particles were scraped and coming to the end, sample density increased and particle size became larger. The degree of classification is represented with the sample density, ρci scraped off at the i-th time as follows,
    S=ni=1/ρci0-1//n
    The values of S can be correlated with the ratio of 50% particle diameter by weight to mean minimum nip clearance. It was found that the values of S increase with increasing this ratio. Moreover, the values of Sw0 was well correlated with this ratio independent on φw0, particle size level and viscosity of vehicle, when the particle size distributions of the mill base can be represented with Rosin-Rammler equation and the constant in regard to sharpness of distribution in this equation is almost equivalent for all mill base. Experimental values of Sw0 were smaller than simulated values which were estimated by assuming that particles were rigid sphere and the scraping efficiency was 100%. Thus it is considered that a dispersion of particle agglomerate and a lowering of scraping efficiency occured in practice. By the simulation with the consideration of these effects, the change of ρc can be predicted.
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  • Toshihiko NAKAMICHI
    1984 Volume 57 Issue 12 Pages 643-651
    Published: December 20, 1984
    Released on J-STAGE: November 20, 2012
    JOURNAL FREE ACCESS
    A series of different molecular weight, hydroxyl contained acrylic oligomers having same monomer compositions were cross-linked with monomeric melamine resin. The study of the cured films included the effect of oligomer molecular weight on physical properties as function of baking temperature and UV-condensation cycle weathering exposure time. Dynamic visco-elastic measurement and tensile testing were mainly used in this study.
    Physical properties of high solids acrylic coating films were greatly influenced by oligomer molecular weight as follows ;
    (i) The influence of baking temperature on physical properties of cured films was increased with decreasing oligomer molecular weight.
    (ii) Knoop hardness number, glass transition temperature (Tg) and tensile strength were decreased, and tangent δ, molecular weight between cross-links (Mc) and elongation were increased with decreasing oligomer molecular weight. In this study, it was found that the molecular weight effect on physical properties depended on the free terminal group for the oligomer Mn>1000 ; for the oligomer Mn>1000, the existence of non-functional or mono-functional oligomers promoted the deterioration of physical properties.
    (iii) Tg of the film depends on the oligomer's Tg, and it can be explained in the formula Tg=Tg-K/Mn.
    (iv) Concerning highly cross-linked polymers as in high solids coating films, the formula log10G=7. 0+293 ρ/Mc is more accurate than the rubber elasticity theory formula for the calculation of molecular weight between cross-links.
    (v) The change of physical properties of lower molecular weight oligomer system during the exposure in the accelerated weathering test was greater than that of higher molecular weight oligomer system.
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  • Fukuji SUZUKI
    1984 Volume 57 Issue 12 Pages 652-659
    Published: December 20, 1984
    Released on J-STAGE: November 20, 2012
    JOURNAL FREE ACCESS
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  • Toyohiko YOSHIDA
    1984 Volume 57 Issue 12 Pages 660-666
    Published: December 20, 1984
    Released on J-STAGE: November 20, 2012
    JOURNAL FREE ACCESS
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