Journal of the Japan Society of Colour Material
Online ISSN : 1883-2199
Print ISSN : 0010-180X
ISSN-L : 0010-180X
Volume 75, Issue 12
Displaying 1-7 of 7 articles from this issue
  • Kunio ESUMI, Keiko MIYAMOTO, Tomokazu YOSHIMURA
    2002 Volume 75 Issue 12 Pages 561-567
    Published: December 20, 2002
    Released on J-STAGE: November 20, 2012
    JOURNAL FREE ACCESS
    Gold nanoparticles are prepared in aqueous solutions by using poly (amidoamine) (PAMAM) dendrimers (generation 3.0, 3.5, 5.0 and 5.5) with various terminal groups such as methyl ester, amino, carboxyl, or sugar residue, and their mean particle sizes are 2-6 nm in diameter depending on the dendrimer/Au+3 ratio as well as the generation of PAMAM dendrimers. Studies of reduction reaction of 4-nitrophenol by gold nanoparticles with NaBH4 reveal that the rate constant depends on the concentration of the dendrimers added as well as the generation of the dendrimers. Furthermore, the effect on the rate constants for PAMAM (generation 5.0 and 5.5) with various terminal groups follows the order : carboxyl ≥ amino > sugar residue > methyl ester. These results are attributed to the dendrimer-gold nanocomposite structures, depending on whether the gold nanoparticles are formed inside or outside the dendrimers.
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  • Yasuo OKAMOTO
    2002 Volume 75 Issue 12 Pages 568-572
    Published: December 20, 2002
    Released on J-STAGE: November 20, 2012
    JOURNAL FREE ACCESS
    In order to confirm whether cross-flow filtration could be adopted for classification of dispersion or not, we measured transmittance performance of dispersed particles. A pigmented ink was filtered with “Pall TFF (tangential flow filtration) Membrane Cassette” at various operating conditions. Flux increased when TMP (transmembrane pressure) was increased up to 0.05 MPa. Then it leveled off regardless of pressure in up to 0.1 MPa. Flux increased when CFF (cross-flow flux rate) was increased. Transmittance performance of dispersed particles changed by operation conditions, such as TMP and CFF. Test results suggested that cross-flow filtration could be adopted for the classification of dispersion by the optimization of the operating conditions.
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  • Takeshi HATTORI, Makoto ISHIZU, Munetaka KAKIUCHI
    2002 Volume 75 Issue 12 Pages 573-578
    Published: December 20, 2002
    Released on J-STAGE: November 20, 2012
    JOURNAL FREE ACCESS
    Flow properties of carbon black (CB) dispersed printing inks were studied. In oscillatory rheological measurements, printing inks showed pseudo sol-gel transition behavior, and critical gel concentration (Wgel) was determined. Wgel was applied as an index to express fluidity of the printing inks, since Wgel was found to show fairly good correlation with BET surface area that is known as a major factor of the fluidity. Moreover, Wgel showed better correlation with CB's external surface area that was determined from electron microscopy and that from mercury porosimetry. Furthermore, Wgel showed the best correlation with CB's specific surface area of the effective volume fraction calculated from relative viscosity in steady state rheological measurements by using a semi empirical model. These results showed that the network structure at Wgel is constructed of complex particle made up of CB and polymer-adsorbed layer on it, not from CB's primary particle as understood generally.
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  • Miyuki NISHIMURA, Takahiro FURUTANI, Nagayuki TAKAO
    2002 Volume 75 Issue 12 Pages 579-585
    Published: December 20, 2002
    Released on J-STAGE: November 20, 2012
    JOURNAL FREE ACCESS
    We developed an encapsulated pigment using a coacervation method in order to have fine pigment dispersion in silicone oil and to add some functions on the surface of pigments. Poly- (dimethylsiloxane) -grafted acrylic polymer was used as a polymer for the encapsulation. A dispersion of the encapsulated pigments with the mean particle diameter of less than 200 nm was prepared. The dispersion had higher zeta potential compared with those prepared using conventional dispersants, which suggested a possibility of the addition of new functions on the surface of pigments. The viscosity of the dispersion was low, and its storage stability was improved by cross-linking of the polymer. All CMYK colored pigments, of which surface property was different, were encapsulated, resulted in the identical surface property with that of the polymer layer.
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  • Masakazu ENOMURA, Kazuya ARAKI, Masahiko YOKOSUKA, Kei TAKEBAYASHI, Ma ...
    2002 Volume 75 Issue 12 Pages 586-591
    Published: December 20, 2002
    Released on J-STAGE: November 20, 2012
    JOURNAL FREE ACCESS
    At present, such mills that use small size beads are main dispersers in the production lines of electronic materials, paints, cosmetics, inks, etc. The desired additional functions for the conventional dispersers are as follows : higher dispensability ; prevention of contamination without using sand, beads, or balls ; broader manageable viscosity range ; one-path treatment instead of cyclic treatment ; lower power ; easier temperature control ; higher mechanical safety and educability with closed structure, simple structure, and compactness, etc. A new type disperser (Trade name : CLEAR SS 5) has been developed to meet the above demands.
    The structural features of this disperser are that it consists of two ringlike disks facing against each other, either or both of which can rotate and one of the disks is at a fixed position while the other has a floating mechanism to absorb alignments. The disk with a floating mechanism can be set up so that the clearance of the dispersion mechanism is constant because it is pressed with air and a spring from the back. Adjustment in the clearance between the disks depends on the velocity of rotation, fluid viscosity, fluid feeding pressure, shape and depth of spiral groove and spring back pressure, and a pressure balance produced can hold clearances between several micrometers and several tens micrometers. Materials to be treated pass through the small clearance part in the tangential direction experiencing a large shear force.
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  • Makiko MORI, Rie TOMITA, Harunori GOJI, Satoshi URANO
    2002 Volume 75 Issue 12 Pages 592-597
    Published: December 20, 2002
    Released on J-STAGE: November 20, 2012
    JOURNAL FREE ACCESS
    The color strength is one of the most important performances in paint and ink industries. The color strength can be improved by the improvement of pigment dispersibility in paint with reduced diameter of the primary pigment particle. In this paper, dry milling of the colored pigment in the presence of extender pigment for better pigment dispersibility and higher hardness was studied.
    Consequently, color strength was sharply improved by using this technique. Dry milling of colored pigment was promoted by extender pigment, and ultra fine colored pigment particle was prepared, which resulted in higher the color strength. The effect of the extender pigment on the dispersibility of the colored pigment was not found in this examination.
    From the observation of the paint film with transmission electron microscope, the pigment particle size and the pigment dispersibility were found to be evaluated individually.
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  • Based on papers appeared in Journal of JSCM
    Toshikatsu KOBAYASHI
    2002 Volume 75 Issue 12 Pages 598-605
    Published: December 20, 2002
    Released on J-STAGE: November 20, 2012
    JOURNAL FREE ACCESS
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