紫外光固化聚氨酯丙烯酸酯的二维红外光谱

Two-Dimensional Correlation IR Spectra of UV Curing Polyurethane Acrylate

通过二维相关光谱分析方法,对PUA(聚氨酯丙烯酸酯)树脂的紫外光固化过程中羰基区和不饱和双键区的谱带变化规律进行了研究。在含有以IPD I(异佛尔酮二异氰酸酯)/PCDL 5652(聚碳酸酯二醇)/HEA(丙烯酸乙酯)/HDDA(己二醇二丙烯酸酯)型PUA树脂和HDDA、TM P-TA(三羟甲基丙烷三丙烯酸酯)、NVP(N-乙烯基吡咯烷酮)的紫外固化配方中,NVP羰基伸缩振动位于1 705 cm-1附近,TM PTA中的羰基在1 725 cm-1附近,HDDA和PUA上HEA片段的羰基伸缩振动都发生在1 715 cm-1附近。随着紫外固化过程中双键的交联,丙烯酸酯官能团上的羰基发生蓝移,逐渐变化为高频率1 735 cm-1和1 740 cm-1附近的羰基。和不饱和双键关联的羰基偶极矩变化的次序为:1 705 cm-1>1 725 cm-1>1 715 cm-1;对应的双键反应活性次序为:NVP>TM PTA>HDDA^HEA。表明在该紫外固化体系中,不同反应官能团之间的相对活性可以通过二维相关光谱由与之关联的羰基偶极矩的变化次序来对比。

Variability of spectrum profiles in the carbonyl region and the unsaturated double carbon bond region were examined by two-dimensional correlation IR techniques. The result of analysis indicates that, in the UV-curable formulation of PUA （polyurethane acrylate） synthesized from IPDI （ isophorone diisocyanate） /PCDL5652 （polycarbonate diol） /HEA （hydroxyl ethyl acrylate） /HDDA （hexanediol diacrylate）, which contains the ingredients of HDDA, TMPTA （trimethylol propane triacrylate） and NVP （N-vinyl pyrrolidone）, the absorption of carbonyl stretching vibration in NVP appears at - 1 705 cm^-1, TMPTA -1 725 cm^-1, HDDA and HEA segments in PUA -1 720 cm^-1. The absorption bands of carbonyl groups in acrylate segments blue-shift, and that of NVP red-shifts with the crosslinking of the double carbon bonds during the UV curing process. According to 2D correlation analysis, the re-orientation order of electric dipole-transition moments of the carbonyl groups should be as follow： 1 705 cm^-1〉l 725 cm^-1〉l 715 cm^-1, which indicates that the relative reactivity of different reactive groups in the UV curable system can be detected by 2D correlation spectroscopy.