NIPPON GOMU KYOKAISHI
Print ISSN : 0029-022X
Volume 46, Issue 9
Displaying 1-5 of 5 articles from this issue
  • [in Japanese], [in Japanese]
    1973 Volume 46 Issue 9 Pages 717-727
    Published: 1973
    Released on J-STAGE: April 16, 2008
    JOURNAL FREE ACCESS
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  • [in Japanese]
    1973 Volume 46 Issue 9 Pages 728-734
    Published: 1973
    Released on J-STAGE: April 16, 2008
    JOURNAL FREE ACCESS
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  • Yasushi MASUDA, Shigeharu ARAI
    1973 Volume 46 Issue 9 Pages 773-778
    Published: 1973
    Released on J-STAGE: April 16, 2008
    JOURNAL FREE ACCESS
    Vulcanization of epichlorohidrin rubber was investigated using the systems comprising thiuram compounds. Thiuram compounds were activated with strongly basic metal compounds, such as calcium hydroxide to give the vulcanizates of improved properties. The most active of thiuram compounds was dipentamethylenethiuram tetrasulfide, which contained the longest polysulfide linkage.
    Furthermore thiuram compounds exhibited a synergestic effect with thioureas. In this composite vulcanization systems the metal compounds added as acid scavangers were limited by the adaptability toward the both components, calcium hydroxide and ceric oxide being assumed to be favorable.
    The above-mentioned vulcanization systems could be applied to the covulcanization of epichlorohydrin rubber with unsaturated rubber provided that proper choice of metal compounds was made.
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  • Y. Nakamura, K. Mori, S. Oka
    1973 Volume 46 Issue 9 Pages 779-787
    Published: 1973
    Released on J-STAGE: April 16, 2008
    JOURNAL FREE ACCESS
    Vulcanizing rate of polyepichlorohydrin (CHR) with 2-R-4, 6-dimercapto-s-triazine (I) is influenced by the structure of R, and the rate increases in order of R: SH<OCH3<N(C4H9)2. In addition, the rate is remarkably increased by the copresence of amines with pKa over 9 such as 1, 3-diphenylguanidine. The organic or inorganic salts of the amine as well as the amine generator such as N-cyclohexyl-2-benzothiazole sulfenamide or Cu-dibutyldithiocarbamate show the similar accelerating activity. The mechanical properties of the vulcanizates with I are improved with the increasing of hydrohobicity of R, i. e, in order of SH<N(C2H5)2<N(C4H9)2<N(C6H5)2, N(C6H11)2<N(C8H17)2. The thermal ageing stability is not improved in the presence of commone antioxidant such as phenyl-β-naphthyl-amine and t-butylphenol novolak. The latent vulcanizing agents, however, show the remarkable stabilizing activity. The best examples are 2-mercaptobenzi-midazole and Ni-dibutyldithiocarbamate, which are used as antioxidant. The vulcanizing compositions of trithiocyanuric acid-MgO-1, 3-diphenylguanidine, and 2-dibutylamino-4, 6-dimercapto-s-triazine-MgO give the most excellent vulcanizates in thermal ageing stability and mechanical property in comparing with the well known composition, e.g. 2-mercaptoimidazoline-Pb3O4, and hexamethylenediamine carbamate-Pb3O4.
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  • PREPARATION OF COPRECIPITATED SBR WITH VARIOUS TYPES OF SILICATES AND THEIR PROPERTIES
    Hideaki TAKAMATSU
    1973 Volume 46 Issue 9 Pages 788-797
    Published: 1973
    Released on J-STAGE: April 16, 2008
    JOURNAL FREE ACCESS
    To a mixture of SBR latex with dilute sodium silicate solution an insolubilizing agent (for example HCl, CaCl2, MgCl2, SrCl2, BaCl2, FeCl3, CoCl2 and CuSO4) is added with rapid stirring, rubber and silicate are both coprecipitated and admixed intimately. The coprecipitated materials are vulcanizable by conventional processes. Tesile strength and tear resistance of the vulcanizates are higher than those of the conventional milling compounds are shown.
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