Effects Of Light Intensity On Photopolymerization

Light intensity is one of the main factors which have great influence on photopolymerization. Proper light intensity will improve the double bond conversion(C=C) of coatings. Better double bond conversion will bring better adhesion, scratch resistance, corrosion resistance and gloss. This proper light intensity is related to the type of photiinitiator and curing environment. If coatings cured in the air, oxygen will decrease the double bond conversion, the best light intensity will be changed. Photopolymerization system is made up of photoinitiator, monomer and oligomer. In the previous study, people usually focus on the modification and grafting of photoinitiator, monomer or oligomer. this article is explore the effects of light intensity on the photopolymerization. Different photoinitiator needs different wavelength, the most appropriate light intensity for this photoinitiator is also different. The content and conclusions are described as follows:1、Through using RT-FTIR, the kinetics of OXE-1, OXE-2and9PA was studied under different light intensity. The increasing light intensity is not always good for photopolymerization. When the light intensity increased to a certain degree, the double bond conversion began to decline.2、Through using UV/vis spectrometer, the photolysis of these three photoinitiators were carried out under different light intensity. The remaining rate of these three initiators had been calculated, the results showed that high light intensity would bring high remaining rate.3、The surface of coatings cured under different light intensity was studied using CRM. There are two reasons which limit the double bond conversion, oxygen inhibition and light intensity. The improper crosslinking rate would decreased double bond conversion.4、At last, the photolytic products of OXE-1and9PA were explored using LC-MS. Under high light intensity, the products of Type II is less than Type I.