Abstract
Polyurethanes, synthesized by polyester polyols and aliphatic or aromatic diisocyanates for a crease resist finishing agent, were prepared by two-step reactions, that is, prepolymer synthesis and chain extension. The structures of synthesized polyurethanes were confirmed by the measurement of FT-IR and $^1H$-NMR spectrometer. The number average molecular weight ($\bar{M}_n$) and the weight average molecular weight ($\bar{M}_w$) of the polyurethane with aromatic diisocyanate (MDI) were higher than those of the synthesized polyurethanes with aliphatic diisocyanate (HDI, $H_{12}MDI$). The glass transition temperatures ($T_g$) of soft segments in polyurethanes with MDI, HDI, $H_{12}MDI$ were -25,-42 and -50$^{circ}C$, respectively. In the polyurethanes obtained by two-step reaction, thermal stability and tensile strength increased with increasing hard segment contents, whereas elongation at break decreased with increasing hard segment contents.
본 연구에서는 섬유의 구김을 방지하기 위해 첨가제인 폴리우레탄을 2단계 중합반응을 통하여 합성하였으며, 단계 반응 중합체의 구조와 합성된 폴리우레탄의 구조를 FT-IR과 $^1H-NMR$ 스펙트럼으로 확인하였다. 방향족 이소시아네이트인 4,4-diphenylmethane diisocyanate(MDI)로 합성한 폴리우레탄의 평균 분자량이 지방족 이소시아네이트인 hexamethylene diisocyanate(HDI), 4,4-dicyclohexylmethane diisocyanate($H_{12}$MDI)로 합성한 폴리우레탄의 분자량보다 크게 증가하였다. 또한 MDI, HDI, $H_{12}MDI$로 합성한 폴리우레탄의 유리전이온도($T_g$)는 각각 -25, -42, -50$^{circ}C$로 나타났다. 합성 폴리우레탄의 경질부분 함량이 증가함에 따라 열 안정성과 인장강도는 증가하였고, 파괴점에서의 연신율은 감소하였다.
