Polymer(Korea) (폴리머)

The Polymer Society of Korea (한국고분자학회)
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Dynamics and Instability of a Polymeric Paint in Roll Coating Process for Automotive Pre-coating Application

자동차 선도장을 위한 롤코팅 공정에서 고분자 도료의 동적 거동 및 불안정성

  • Kim, Jin-Ho (Department of Chemical and Biological Engineering, Korea University) ;
  • Lee, In-Jun (Department of Chemical and Biological Engineering, Korea University) ;
  • Noh, Seung-Man (Department of Chemical and Biological Engineering, Korea University) ;
  • Kang, Choong-Yeol (Advanced Research Team, PPG Industries Korea) ;
  • Nam, Joon-Hyun (Advanced Research Team, PPG Industries Korea) ;
  • Jung, Hyun-Wook (Department of Chemical and Biological Engineering, Korea University) ;
  • Park, Jong-Myung (Graduate Institute of Ferrous Technology, POSTECH)
  • 김진호 (고려대학교 화공생명공학과) ;
  • 이인준 (고려대학교 화공생명공학과) ;
  • 노승만 (고려대학교 화공생명공학과) ;
  • 강충열 (PPG Industries Korea 선행연구팀) ;
  • 남준현 (PPG Industries Korea 선행연구팀) ;
  • 정현욱 (고려대학교 화공생명공학과) ;
  • 박종명 (포항공과대학교 철강대학원)
  • Received : 2011.05.04
  • Accepted : 2011.07.12
  • Published : 2011.11.25
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Abstract

3-Roll coating process as a key application technology for manufacturing automotive pre-painted metal-sheets has been studied. The 3-Roll coating system for this study consists of pick-up roll for picking up and distributing coating liquid from the reservoir, metering roll to properly meter coating liquid in metering gap regime, and applicator roll for directly transferring liquid into metal-sheet surface. Flow dynamics and operable coating windows of a polymeric paint (primer) with shear-thinning rheological property have been correlated with processing parameters such as speed ratio and metering gap between pick-up and metering rolls. In the uniform coating regime, dry coating thickness increased with increasing metering gap or decreasing speed ratio. Ribbing and cascade instabilities were observed in low speed and high speed ratio conditions, respectively. It is revealed that lower speed ratio makes severity and wavelength of the ribbing increase, aggravating flow instability in coating systems.

자동차 선도장 강판을 위한 핵심 응용기술로서 3-롤코팅 공정을 연구하였다. 본 연구를 위한 3-롤코팅은 저장조로부터 코팅액을 끌어 올리는 pick-up롤, 적절한 코팅 두께로 계량시키기 위한 계량롤, 강판에 직접 코팅시키기 위한 applicator 롤로 구성되어 있다. 전단담화의 유변물성을 갖는 고분자 도료의 코팅 유동 특성과 코팅 운전 영역을 pickup 롤과 계량롤 사이의 속도비와 간격 등의 공정조건과의 상관관계를 통해 고찰하였다. 안정한 코팅 영역에서, 간격이 크거나 속도비가 작을수록 코팅 두께는 증가하였다. 또한, ribbing과 cascade라는 불안정성은 각각 속도비가 낮고 높을 때 관찰되었다. 특히, 속도비가 낮을때, ribbing의 파장과 심각도가 증가함을 확인하였다.

Keywords

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