The Synthesis And Properties Of UV-curable Unsaturated Polyester-Urea Resins

The ultraviolet cured coating is one kind of environmental protection coatings which were developed in the 1960s. It has the advantages of non-contamination, non-toxicity, non-skin irritation which receive enormous attention. In China, with the development of economy and growth of environmental protection concern, as environment-friendly"green technology"the research, development and applications of ultraviolet cured coating are growing in popularity.This paper introduces UV-curable unsaturated polyester-urea resin. The UV-curable unsaturated polyester-urea resin system was composed of the polyester-urea resin as the main monomer, the dilution monomer, other fillers and the assistant compounds. The main results are as follows:The new unsaturated polyester resins were prepared by melt polycondensation of the corresponding mixed monomers: maleic anhydride, sebacic acid or phthalic anhydride, propanediol, neopentyl glycol and urea. The raw materials ratio of synthetic reaction, reaction degree and polymerization inhibitor species and dosage were studied in detail. The optimum composition of the unsaturated polyester-urea resin was obtained under such parameters: e'=0.0675, SA:PA =4:1, PG:NPG =7:1, acid value =50, 0.015% polymerization inhibitor(hydroquinone)content.Many factors on solidification were studied. The influence of photoinitiator and active diluent on curing-velocity and gel content were analyzed. The effects of active diluent on properties of the coating such as hardness and adhesion were discussed. The optimum curing conditions of the unsaturated polyester-urea resin were obtained under such parameters: 3%-4% photoinitiator(benzoin dimethyl ether ) content, 50% active dilution concentration.From the UV-Sorbspectrum of photoinitiators, it can be found that the absorb peak of benzoin dimethyl ether is bigger than that of other photoinitiators which proves that benzoin dimethyl ether is more effective than other photoinitiators.To analyse the variation in double bond of UV curing in the course of U V-curing, the FTIR spectrometry was used to track the conversion rate of double bond. Through the TG/DSC, it can be found that the coating has excellent thermal stability.