The dichloro-polyester polyol (DCBAO) which was synthesized in our earlier work was cured at room temperature with two different type of curing agents including Desmodur N-3300 and Desmodur L-75 to get a polyurethane flame-retardant coatings (DCBAO/N-3300=DCBAN and DCBAO/L-75=DCBAL). We could not observe any deterioration of physical properties of the flame-retardant PU coatings (DCBAN and DCBAL) in comparison with the conventional PU coatings. Thermal resistance of DCBAL-type flame-retardant coatings, which was measured by yellowness index difference, was inferior to that of DCBAL-type PU coatings. We believe that this phenomena is attributed to the poor thermal resistance of Desmodur L-75 isocyanate. It was observed that the LOI values were 25∼26% for the PU coatings containing 20∼30 wt% of 2,4-dichlorobenzoic acid.

전보에서 합성한 디클로로-폴리에스테르 폴리올(DCBAO)에 2종류의 이소시아네이트 경화제인 Desmodur N-3300과 Desmodur L-75를 선택하여 상온경화시켜 PU계 난연도료 (DCBAO/N- 3300=DCBAN 및 DCBAO/L-75=DCBAL)를 각각 제조하였다. 제조된 DCBAN과 DCBAL 도료로서 도막물성을 측정한 결과, 양쪽 모두의 도료가 난연처리 후에도 물성저하 현상을 초래하지 않았으며, 별도의 황변성 시험에서 황변성은 DCBAL 쪽이 다소 불량하게 나타나 Desmodur L-75가 황변성과 관련이 있음을 알았다. 또한 난연성분인 2,4-dichlorobenzoic acid의 함량 20∼30 wt%에서 LOI 값 25∼26% 선의 난연효과를 보여주었다.

Keywords: dichloro-polyester polyol; isocyanate; PU flame-retardant coatings; LOI