| The ultraviolet (UV) curable coatings are a type of high-performance and energy-savingcoatings. More and more attention has been received in recent years. The UV-curable coatingshave many advantages, such as fast curing speed, high energy utilization, less emission of thevolatile organic compounds (VOC), environmentally friendly, and applying on varioussubstrates. However, the UV-curable coatings have some disadvantages, such as restriction ofcuring depth, difficult application in colorful UV coatings, failure curing of shaded part andrestriction in the shapes of objects. The UV-heat dual-curing system was chose to overcomethe disadvantages, in which the heat curing is used to eliminate the deficiency of the UVcuring. In order to reduce the cost, the UV-heat dual-curing system was conducted under alow temperature.In this study, epoxy acrylate (EA) was chose as the main resin. Low-temperature andeasy-dry epoxy acrylate resin was synthesised by applying new process and formulation. Tomake the synthetic resin can be cured under the low temperature, firstly toluene diisocyanate(TDI) reacted with trimethylolpropane diallyl ether (TMPDE) to synthesis the pre-polymer,then made the pre-polymer react with EA to obtain low-temperature and easy-dry resin. SoEA was connected to the air-drying group----the allyl ether group and TDI played a bridgefunction. With acrylic acid and epoxy resin E-51as raw material, the synthesis process weredetermined as follow: triethylamine was selected as the catalyst, the content was0.9%of thequality of the used E-51; the reaction temperature was between90℃and110℃;p-hydroxyanisole was selected as polymerization inhibitor, the content was0.02%of thequality of the used E-51; acrylic acid was dropped in two hours; the equivalent ratio of epoxygroup to carboxyl group was1.05:1. The effects of the pre-polymer contents on the air-drying property of the product were studied by the tests o f surface drying time. The resultsshowed that the performance of product with mass ratio of pre-polymer to epoxy vinyl resin1:6was the best.The UV-heat dual-curing coatings were prepared by adding some suitablephoto-initiators, thermal initiator and thermal accelerator. The chemical structure of theproduct was characterized by FTIR. Dry time, hardness, adhesion and water resistance were tested. The heat resistance of the cured film was analyzed by TG. The synthetic resin could beboth UV-cured and heat-cured. By adding initiator and accelerator into the resin, not only canit be cured fast under the ultraviolet light radiation, but also the surface could be dried withinone hour in condition that heated separately at a temperature of50deg C. Compared to thetraditional thermal curing, the dry time and the heating temperature ware greatly reduced. Theinfluencing factors of UV-curing films and heat-curing films were studied; the properties ofthe cured film were tested and the chemical structure of the product was characterized byFTIR. By characterizing the films, the research shown that the films were cured in high leveleither by UV-curing or heat-curing, the gel content can reach90.34%. It also showed thecured film had a excellent heat resistance by the analysis of TG.The UV-heat dual-cured matte coatings were prepared. The influential factors on thegloss of films were studied and analyzed. The research figured out the essential formulationsof the UV-heat dual-cured matte coatings. Through the test of properties of the film, theconclusion was obtained that it remained comprehensive performances by heat-cured orUV-cured or dual-cured. The gel content could reach90%or more, UV-cured film’s hardnesscould reach2H, but its flexibility was worse than the heat-cured film’s. And the UV-heatdual-curing film’s properties were better than any separate curing film’s. It owed to the highdegree of cross-linking of the film and the high curing level, with a combination of theadvantages of the heat-curing and UV-curing. |
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