Abstract:

The allyl ether modified lacquer(AGE-L) was successfully prepared by the reaction of lacquer with allyl glycidyl ether(AGE), and subsequently reacted with methacrylic anhydride(MAA) to form a novel lacquer-based monomer with ether bond and ester bond(MAA-AGE-L). Their structures were then characterized by FT-IR, ¹H NMR and ¹³C NMR, and their physical and chemical properties were tested. Additionally, the UV and oxygen(air) curing processes of raw lacquer, AGE-L and MAA-AGE-L were investigated, and the mechanical properties as well as the resistances to chemical media of the cured films were also studied. The results confirmed the successful synthesis of AGE-L and MAA-AGE-L, which were all brownish red liquids. The hydroxyl value of AGE-L was 193 mg/g, the iodine value was 1.89 g/g and the viscosity was 400 mPa·s. The hydroxyl value of MAA-AGE-L was 20 mg/g, the iodine value was 1.39 g/g and the viscosity was 2 000 mPa·s. Compared with lacquer, the surface drying time of MAA-AGE-L was shortened from 2 h to 50 min in presence of the oxygen(air) environment at 30 ℃ with the relative humidity of 80%, and the UV curing surface drying time was shortened from 50 s to 10 s. The pencil hardness of the cured film was H when AGE-L was irradiated by ultraviolet light for 120 s, whereas the pencil hardness of the paint film cured under oxygen(air) for one week was 2H. Moreover, they exhibited good adhesion, flexibility and impact strength. Allyl-modified lacquer films obtained by two curing methods had good water resistance, ethanol resistance, salt water resistance and acid resistance.

Key words: lacquer, urushiol, allyl glycidyl ether, UV curing, dual curing