UV Curable Waterborne Hyperbranched Polyester Synthesis And Performance Studies

UV curable coating has been developing rapidly for it s fast curing rate, environment friendly etc. Hyperbranched polymer is a new focus of scientific study for its outstanding physical and chemical properties, such as low viscosity, numerous active ending groups, and simple synthesis process. After being modified, hyperbranched polymer can be implied to different field for the modified ending group, including the field of UV curing coating.In this paper, three kinds of second generations hyperbranched polyester (HBP), which had been modified, were synthesized, and the curing property of modified HBP was studied, so did other properties of the cured film. The AB2 monomer - N, N-diehtanol-3-amine methyl, propionate by Micheal additive reaction of diethanolamine and methyl acrylate, was synthesized, in which A prefers to methyl ester group, and B prefers to hydroxyl group. The monomer has been tested by NMR and IR spectrum.The second and third generation of HBP were synthesized by accurate-one-step method, TMP and EOTMP used as nucleus, using the ester exchange reaction between A and B. The molecule weight distribution of the second generation is 1.1, and the molecule weight is about 1200, which below the theoretical value , tested by GPC. TG proved that the product has good heat stability. And the relationship of the viscosity and the change of temperature was also studied, which showed that the viscosity of HBP will decline rapidly as the rising of temperature.The modified HBP with ending acroloyl-group was synthesized from the reaction among TDI, HEA and HBP; then the modified HBP with ending carboxy group was synthesized from the reaction between maleic anhydride and HBP. Carboxy group is a kind of hydrophilic group. The resin can be easily self-emulsified after being neutralized by rriethylamine. The impact of construction of HBP, the content of photosensitizer , and the coating technique on the curing rate were also studied. The curing rate will be the fastest when the content of photosensitizer was 3%. The property of curing will be better when the extent of neutralization was higher. Drying is unfavorable to curing. The higher content of carboxyl, , better thestability of emulsion will be.The modified HBP with ending acroloyl-group was synthesized from the reaction among TDI, HEA DMPA and HBP. Carboxy group is a kind of hydrophilic group. The resin can be easily self-emulsified after being neutralized by triethylamine or sodium hydrate. The emulsion is very stable. The impact of construction of HBP, content of photosensitizer, and the coating technique on the curing rate were studied. The property of curing and the hardness of film of the system neutralized by sodium hydrate are better than that neutralized by triethylamine. The higher the extent of neutralization is, the better the curing property will be. Drying is unfavorable to curing; the optimum value of photosensitizer is 2%. The effect of the different of nucleus on the curing property is not big.The modified HBP with ending acroloyl-group and photosensitive group was made from the reaction among TDI, HEA DMPA 2959 and HBP. The resin can be easily self-emulsified after being neutralized by triethylamine or sodium hydrate. The emulsion is very stable. Using as initiator itself, the resin can initiate UV coating without photosensitizer. And it will be better than using photosensitizer only. The property of curing and the hardness of film of the system neutralized by sodium hydrate are better than that neutralized by triethylamine. The optimum value of photosensitizer group is 2%. The resin can initiate polymerization using as macromolecule photosensitizer by its own, and the effect of initiation is better than using initiator only. The microstructure of cured film was studied, which proved that microcrystal will occur in sodium hydrate neutralized system.