The Development And Performance Research Of Green Tung Oil Wood Coatings

There are some disadvantages for solvent coatings such as environmental pollution,health hazard and endangering public security,and development of green environmental protection products has become the trend of the coating industry.Tung oil is a pure natural and renewable biomass that re-entered the researchers'vision due to its rich resources and wide application.In this paper,the problems of tung oil application were analyzed.The refined tung oil,polymerized tung oil and tung oil C18 unsaturated fatty acid methyl esters(C18 UFAMEs)were researched,and preparation formulas of tung oil-based wood coatings were designed and optimized.The research contents and results are summarized as follows:1.Taking tung oil as raw material and deacidification rate as evaluation index,the single factor and orthogonal experiments were employed to optimize technological conditions of deacidification.On the basis,the tung oil was treated with adsorption and decolorization,evaluation with the Gardner glass color code.The results showed that deacidification rate of tung oil reached 78.07%under the condition of ethanol concentration 100%,tung oil-to-alcohol 3.5:1,extraction temperature 15?,and time 30min.The tung oil color was decreased from 10-to 5 under vacuum condition,decolorized by activated clay with 10%addition,decolorization temperature of 80?,and time of 75min.The physico-chemical properties and fatty acid methyl ester content of tung oil were determined,and it was found that the refined tung oil had a light yellow color,no odor and fatty acid methyl ester content also increased to 97.1%,indicated that the preparation of refined tung oil was successfully.2.The raw tung oil was refined at 220 ? to prepare polymerized tung oil,then it was characterized by infrared absorption spectrometer(FI-IR)and thermogravimetric analyzer(TG).The results indicated that the double bond polymerization and ester hydrolysis reaction occurred in tung oil during the tanning process,and the polymerized tung oil paint film had the better thermal stability in a certain temperature range.3.The tung oil fatty acid methyl ester was synthesized by the transesterification,then extracted C18 UFAMEs from it,using C18 UFAMEs content and yield as evaluation index.The single factor and orthogonal experiments were employed to optimize technological conditions of extracting,the results showed that the content and yield of C18 UFAMEs reached 99.28%and 54.93%respectively,with the condition of urea-methyl ester ratio 1:1(W/W),ethanol-methyl ester ratio 5:1(V/W),inclusion temperature 5? and time 18h.The urea inclusion compound was characterized by its structure,thermal stability and micromorphology by FT-IR,TG and scanning electron microscopy(SEM).The flash point,boiling point,kauri butanol number(KB)and VOC content of C18 UFAMEs were tested,the results confirmed that it was an environment-friendly solvent.4.Using refined tung oil and polymerized tung oil as main film-forming materials,and C18 UFAMEs as thinner,the formulas of green tung oil-based primer and topcoat were optimized by single factor experiments and orthogonal tests.The primer formula proportion was 25 parts of polymerized tung oil,20 parts of refined tung oil,10 parts of C18 UFAMEs,13 parts of dearomatization solvent,25 parts of turpentine oil,2.5 parts of mixed drier,2 parts of anti-skinning agent,1 part of grinding aid.The topcoat formula was 25 parts of polymerized tung oil,10 parts of refined tung oil,12.5 parts of C18 UFAMEs,3.7 parts of dearomatization solvent,22 parts of turpentine oil,2.5 parts of mixed drier,2 parts anti-skinning agent,5 parts of wax powder,3 parts of anti-settling agent,2 parts of chiral auxiliary,1.5 parts of flavor,1 part of matting powder.The performance of primer and topcoat was tested.The results showed that tung oil based wood paints met the standard requirements of LY/T 2709-2016 wood wax oil.