Synthesis Of UV-curable Resins And Studies On Their Films

Epoxy acrylate (EA) is prepared through ring-opening esterification using epoxy and methyl acrylate. Due to its excellent performance, it is the most widely used and the largest amount of UV-curable oligomer. With the increase of high-tech development and environmental protection requirements, EA attracts the attention increasingly for its high viscosity, poor heat resistance, poor adhesion and enviromental pollution when using dilute monomer. As a result, it has important practical significance to improve the properties of EA and reconstruction of water aiming to reduce the usage of dilute monomer.In order to improve the heat resistance of curing coating, a appropriate monomer was adopted as EA's modified monomer on the basis of alternative synthesis of modified monomer and the study on the physical and chemical properties. The modification involves blending, grafting and waterborne.The special groups such as amide, phenolic hydroxyl, sulfonyl amino and fluorine atom, are introduced into the molecular structure of acrylamide at first. Then three modified monomers named as BDPA, ASPAA and AHPAA were synthesized and comparative study on their heat resistance and solubilities was carried out. Finally, BDPA was selected as the appropriate modified monomer of epoxy resin.The synthesis of BDPA was optimized and the optimum synthesis conditions are as follows:the amount of catalyst, triethylamine is 1.15% of the total mass of feed. The reaction time is 4 h. The reaction temperature is 0℃and the molar ratio of acryloyl chloride and 4-bromo-3,5-difluoro aniline is 1:1.1. Both the purity and yield of BDPA are stable, and the yield is 62.5%.It was necessary to investigate the solubilities of BDPA in different solvents when the modification of EA using BDPA has been carried out. The solubility data of BDPA in benzene, toluene, methanol, ethanol, acetonitrile and pyridine was determined by dynamic method. The solubilities and temperature were correlated by Apelblat equation,λh equation and Wilson equation. The results show that the total average relative deviations are 1.06%,0.93% and9.65% respectively. Meanwhile, the solubility of BDPA in the mixture of methanol and ethanol was also determined. Apelblat equation andλh equation were adopted and it shows that the total average relative deviations are respectively 0.19% and 0.39%.Based on the study above, the acrylate prepolymer ARBDPA containing BDPA was prepared to fulfill the blending modification of EA. The technology of blend coating process was also focused on and under the optimum conditions, hardness is 5 H, adhesion is of one class and the tensile strength is 25 MPa. The retention rate is 18 %, which is 3 times of that of EA coating.The kinetic study on BDPA/MMA/MAA polymerization was carried out using precipitation method. The dynamic relationship obtained is Rp∝[AIBN]0.314 [BDPA]0.864 [MMA]1983 [MAA]0.965 exp(-98.4×103/VRT).The UV-curable modified EA was obtained through grafting by which BDPA was directly into EA. The tensile strength of modified EA curing coating is 28 MPa, the adhesion is of zero class and the hardness is 5 H. The study on mechanical and thermal properties of both modified and unmodified EA curing coating shows the properties of the former is better than those of the latter. To be specific, compared by unmodified EA curing coating, the tensile strength improves by 86% and the retention rate is finally 10.9%, which improves by 4.2%.The factors influencing on modified light-curing rate of EA were investigated. The results indicate that the conversion rate of double bond is 88% after 40 s' irradiation. The photopolymerization rate decreases with the increase of the content of modified EA in the system. The initiator efficiency of cracked initiator is higher than that of hydrogen-based initiator, benzophenone. The activity of TPGDA is better than that of TMPTA.The water-based EA with modified monomer was prepared in the light of the synthesis of modified EA resin. The water dispersion of water-based EA obtained by inversion technique is milky transparent without precipitation. The tensile strength is 19 MPa, adhesion is of one class, water absorption is 6.3% and the hardness is 5 H. TGA residual rate improves in the contrast of unmodified EA.TGA with a combination of single and multiple scanning was involved in the study on thermal decomposition kinetics of the water dispersion of water-based EA. The differential mechanism function pyrolysis in the second phase of obtained curing coating is f(α)=(1-α)2. The thermal activation energy is 206.7 KJ·mol-1. The dynamic model is dα/dT=2.24×1015×(1-a)2 exp(-206.7×103/RT).Generally speaking, the above results suggest that, the heat resistance, adhesion and tensile strength of the curing coatings prepared by a series of UV-curable prepolyner monomers in which BDPA is adopted as modified monomer, are all better than those of unmodified EA coating, which provides theoretical guidance for expanding the application areas of EA.