塗膜の耐候劣化 I.光沢の経時変化  [in Japanese] Deterioration of Coating Films by Weathering Part 1 : Change of Gloss with Time  [in Japanese]

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Abstract

暴露試験による塗膜の鏡面光沢の変化はロジスチック曲線によくしたがう。光沢の上限の値をA, 下限の値をB, 光沢 (y) の関数をf (y) =1n {(A-y) (y-B)} と仮定すると, f (y) を暴露期間に対してプロットすると直線になる。そのプロットの回帰線の決定係数は0.9以上にもなる。回帰方程式の係数を用いて推定した光沢と観測値は非常によく一致した。使用したデータは常乾ウレタン樹脂エナメルを銚子と宮古島で暴露したときの光沢のデータである。<BR>暴露後の残留光沢値の高い少数の試料を除けばA=100, B=0という仮定でかなりよい (光沢の) 近似が得られた。<BR>暴露地が異なるか, 暴露条件が異なったとき, 同じ光沢になるまでの暴露時間の比は, 光沢のレベルによって異なる。劣化速度の比は塗料の種類, 成分の相溶性あるいは親和性, 劣化した性質, 劣化の度合いによって異なるということに注意すべきである。ロジスチック曲線は対称性であるから, 前半をこまかく観察すれば後半を正確に推定することができる。

The changes of specular gloss of coatings by exposure tests obey well to a logistic equation.<BR>When a function of gloss (y), expressed as (y) as f (y) =ln {(A-y) / (y-B)}, <BR>was plotted against exposure time, a straight line was obtained, where A and B are higher and lower limits of gloss, respectively.<BR>The coefficient of determination for the regression of this plot was as high as over 0.9. The calculated gloss using the coefficients in the regression equation matched very well to those observed. The sample data used in this investigation were the gloss of air dried urethane resin enamels exposed at Choshi and Miyakojima. Fairly satisfactory gloss was estimated when A and B were assumed to be 100 and 0, respectively, except for a few samples that had high residual gloss after the exposure.<BR>The ratio of exposure periods to reach a same gloss at different exposure sites or conditions of exposures differed depending on the levels of gloss. We should pay attention that the ratio of the velocities of deterioration differs depending on the varieties of coatings, the compatibility or affinity of the components, properties associated with deterioration, and the levels of deterioration.<BR>Because the logistic equation has a symmetrical shape, detailed observation of the first half enables quite correct estimation of the latter half.

Journal

  • Journal of the Japan Society of Colour Material

    Journal of the Japan Society of Colour Material 75(5), 221-226, 2002-05-20

    Japan Society of Colour Material

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Codes

  • NII Article ID (NAID)
    10008467721
  • NII NACSIS-CAT ID (NCID)
    AN00354634
  • Text Lang
    JPN
  • Article Type
    Journal Article
  • ISSN
    0010180X
  • NDL Article ID
    6168401
  • NDL Source Classification
    ZP23(科学技術--化学・化学工業--染料・顔料・塗料)
  • NDL Call No.
    Z17-211
  • Data Source
    CJP  CJPref  NDL  J-STAGE 
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