酸化剤水溶液中での紫外線照射による酸化チタン含有塗膜の劣化  [in Japanese] Degradation of Coatings Films Containing Titanium Oxide by UV Irradiation in Aqueous Oxidizing Agent Solutions  [in Japanese]

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Abstract

高速耐候性試験法を開発するため, 酸化チタン顔料を含有するアルキドメラミン塗膜に酸化剤水溶液中で紫外線照射処理を50h行った。試料には, 酸化チタン顔料のみを含み樹脂種が異なる4種と有機顔料も含む5種を用いた。酸化剤水溶液は, 40℃の3.0wt%過酸化水素水, 5.0wt%次亜塩素酸ナトリウム水溶液および1.0wt%ペルオキソ炭酸ナトリウム水溶液中を用いた。紫外線照射処理は紫外線蛍光灯 (波長300~400nmで照射強度97W/m<SUP>2</SUP>) を用い, 光沢と表面形態の変化を調べた。<BR>いずれの酸化剤, 塗膜の場合も, 光沢は上記処理によって低下した。この光沢低下は, 酸化チタン顔料周辺の樹脂が消失して穴が形成されて起こった。これは屋外曝露で光沢が低下した酸化チタン含有塗膜に認められる特徴的な現象である。上記現象は酸化剤, 紫外線のいずれかがない場合は認められず, 酸化剤が酸化チタンの光触媒作用を増大させたと推定される。

A new treatment for a rapid weatherability test method for coatings has been studied. Nine alkyd-melamine coatings films containing TiO<SUB>2</SUB> pigment were subjected to UV irradiation of 97 W/m<SUP>2</SUP> (300-400 nm) in aqueous solutions of 3.0-wt% hydrogen peroxide, 5.0-wt% sodium hypochlorite and 1.0-wt% sodium peroxocarbonate for 50 h at 40°C, and gloss and surface morphology were examined. Four coatings were formulated from different resins with a TiO<SUB>2</SUB> pigment, the other five coatings were formulated from different organic pigments with a TiO<SUB>2</SUB> pigment and a resin. These films were also outdoor-weathered in Okinawa for 2 years.<BR>Gloss was decreased with treatment time. SEM observation showed that the gloss loss resulted from formation of small pits by resin loss around TiO<SUB>2</SUB> pigment. The same results were obtained in all cases of oxidizing agents and coatings. The formation of pits is observed in every outdoor-weathered coatings film. Thus our treatment is a rapid method to reproduce outdoor degradation. The resin loss around TiO<SUB>2</SUB> pigment is supposed to be caused by photocatalytic oxidation enhanced by oxidizing agents.

Journal

  • Journal of the Japan Society of Colour Material

    Journal of the Japan Society of Colour Material 75(5), 209-213, 2002-05-20

    Japan Society of Colour Material

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Codes

  • NII Article ID (NAID)
    10008467695
  • NII NACSIS-CAT ID (NCID)
    AN00354634
  • Text Lang
    JPN
  • Article Type
    ART
  • ISSN
    0010180X
  • NDL Article ID
    6168357
  • 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  NDL  J-STAGE 
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