Polyurethane Acrylates Light-curing Coating Preparation And Properties

In this dissertation,a research has been made on the Ultraviolet(UV)cured colored paints and visible light cured varnishes of PUA.We synthesized PUA oligomer two-step at different temperatures by using molecular weight of 800,1000,2000 polyether diols as raw material.In order to verify the feasibility of curing experiment,we have done the ultraviolet-visible absorption test of ITX/EDAB,BP/MK and BP/TEA.After testing some parameters of the films which contained different diluents,we discussed their respective advantages and disadvantages.Also we studied the floeability and storage stability of liquid coatings,and then detected and optimized the physical and chemical properties of curing films.The results show that we can synthesize polyurethane acrylate by adding 0.1 percent catalyst and maintaining the reaction temperature of the first step at 70℃,the 2nd step temperature at 50℃.After reaction for 9 hours,-NCO content is＜0.5 percent,which could be approved by the infrared spectrometry.ITX/EDAB and BP/MK cause a better curing result.The best amount of both the initiators in UV-curing is 4%to 8%,the best amount in visible light cured is 6%.Liquid paint could be completely cured in 40s under one 500 W ultraviolet mercury lamp,which would be prolonged to 1.5 hours in the natural visible light.Pigments could extend the curing time.In order to enable the conduct of curing,the maximum of the chrome yellow and ferric oxide is 7%,and the maximum of TiO₂ is 10%.Multi-functional diluents have faster curing rate,but at room temperature their coatings are hard and crisp.Mono-functional diluents are contrary to multi-functional diluents,so we use DPGDA(dual functionality)and BA/GMA(mono-functionality)as the mixed diluent.By this way,the glass transition temperature(T_g)of the cured films is -20℃around,the biggest strain is≥40%,the tensile strength is about 2～2.5MPa.Also the chemical resistance is excellent,and the adhesion enhances 1～2 levels by coupling agent dealing with the substrate surface.