Development of Natural Oil Based Wood Coating Materials with the Use of Isocyanate as Cross-linker

For the development of two-part type natural oil based coating materials, tung oil and isocyanate was used to increase water-resistance and toughness after curing process.Heavy metal catalysts such as cobalt-naphthenate, manganesoctoate, and zinc-naphthenate was added into tung oil to accelerate oxygen mediated curing process.Optimal ratio of tung oil: isocyanate was selected by curing time, surface morphology after curing and water resistance experiment.The contact angle was measured to reveal hydrophobicity of cured coating materials on the wood sample.To follow the curing process, Fourier transform infrared spectroscopy (FT-IR) was used.2,270 cm -1 peak, which originates from N = C = O (isocyanate) had almost disappeared, and 3,370 cm -1 peak (N-H stretching), which is supposed to arise from the reaction of isocyanate and carboxylic acid of -eleostearic acid, newly generated.With other peaks variations in FT-IR chromatogram, isocyanate seems to make an active chemical bond with various functional group of tung oil.Water resistance was compared on the surface of wood sample with different natural oil based coating material.Isocyanate added tung oil leaved no water mark after 12 hours of contact with double distilled water (D.D.W.), whereas pure tung oil, pure linseed oil, and isocyanate added linseed oil leaved easily observable water mark.