Study On Influence Of α-Aminoketone Photo-initiator To UV-heat Dual Curing Of Filled Epoxy Acrylate/epoxy Resin System

UV-curing is a low energy consumption, high productivity, low cost and enverionnmental friendly technique. It has found manifold industial applications in coatings, printing inks, adhesives and other UV-sensitive products. But the performances of the UV-cured products are affected by the thickness and filler content seriously because the UV curing relies on the penetration of UV radiation. The uitilization of the UV-curing technology is blocked in some areas due to this drawback. UV-dark dual curing may be an effective way to make up the disadvantage of UV curing and photolantent base initiators may make UV curing technology more workable. Under UV irradiation the photolantent base initiator will generate free radicals to initiate cross-linking reaction immeadtely; after UV exposure, the alkaline substances from the photolysis of the initiator can catalyze other cross-linking reactions continually, complemently curing the shadow or bottom portions. Photolatent base initiator has become a hot topic in the development of UV curing.This thesis has addressed the curing characteristics of anα-aminoketone photoinitiator PI-369. PI-369 was added to filled epoxy acrylate system and epoxy acrylate/epoxy resin hybrid system. The UV curable resins were exposed to UV radiation and elevated temperature; the catalyzing effect of PI-369 on the free radical reaction of acrylic resin and cationic reactions of epoxy resin were studied. The catalyzing ability of PI-369 to epoxy groups was analyzed with DSC before and after UV exposure. The gel contents and mechanical properties were measured after UV irradiation and UV irradiation followed by post heating. The effect of post curing conditions on gel contents of the hybrid system were studied in details. The effect of UV-heat dual curing on the properties of the filled hybrid resin system was investigated.Epoxy acrylate resin systems with 3 phr PI-369 exhibited gel content of 98 % and tensile strength of 48MPa. But filler reduced the gel content and tensile strength. At 30 phr CaCO3, the gel content and tensile strength decreased to 84% and 23MPa, respectivly.DSC experiment demonstrated that the photolyzed fragments of PI-369 could catalyzed the the reaction of epoxy group. The initial exothermic temperature of epoxy resin could be reduced from 135℃to 95℃after UV irradiation, indicating that PI-369 possesses the features of photolatent base. It makes the activation temperature of the hybrid resin system drop to 50℃. The hybrid resin system could change from liquid to solid after UV exposure, but the gel content was just about 45 %. Post-curing could enhance the gel content to 95% or more. From 60 to 120℃, the gel content increased with increasing post-curing temperature and duration. The hybrid resin system with 3 phr PI-369 exhibited gel content above 92 % after UV exposure and post-curing at 80℃for 12 hr. The gel content of the hybrid resin system filled with 30 phr CaCO3 could be above 92 % after UV-heat dual curing, being 8 % higher than that of filled acrylic resin system. PI-369 is an effective phtolanten base and the hybrid resin system with PI-369 may overcome the negative effect of fillier.