Effects of hybridization of lacquer sap with organic silane on drying properties

A hybrid lacquer that dries quickly in low relative humidity was synthesized from liquid kurome lacquer and N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (AATMS). Hybridization improved the film (mechanical strength and thermal stability) and drying properties of lacquer paints fairly well. The reaction mechanisms between lacquer sap and AATMS were evaluated by various techniques, including NMR spectroscopy, IR spectroscopy, and GPC analysis. The reaction mechanisms were confirmed by the shifts of aromatic proton/carbon signals and the appearance of a methanol peak at the cleavage of the methoxysilyl groups (Si–O–CH3) and phenolic hydroxyl groups (Ph–OH) of urushiol that were demonstrated by various NMR spectra and IR spectra. Due to these reactions, high molecular weight contents were increased. We considered that the drying properties of the hybrid lacquer were improved by the combination of alcoholysis, the sol–gel reaction, and general curing reaction of lacquer sap.