Study On Preparation Of UV-LED Curing Epoxy Soybean Oil-based WPUA Resin And Its Application In Wood Coatings

Traditional wood coatings are mostly solvent-based coatings,which have a lot of harmful volatiles and serious pollution.They also use petroleum raw materials and consume a lot of fossil resources,which has caused a huge burden on modern society.Therefore,people began to use water-based systems to replace traditional coatings.However,water-based systems themselves also have problems such as slow curing speed and poor mechanical properties.In response to these problems,this paper used epoxy soybean oil as the biomass raw material to synthesize epoxy soybean oil-based wood coating WPUA emulsion,and used UV-LED light curing technology to achieve rapid curing of the coating at 395nm.The mechanical properties of the coatings were further improved by adding cellulose nanofibers.Firstly,modified epoxy soybean oil(AESO)was used to prepare a UV-LED curable epoxy soybean oil-based WPUA emulsion.Through infrared and hydrogen spectrum analysis,the UV-LED curing epoxy soybean oil based WPUA emulsion was successfully prepared.When the content of AESO was 45.0%,the ratio of-OH/-NCO was 0.900,the amount of DMPA was 7.0%,and the amount of PETA was 5%,the average particle size of the obtained emulsion particles was about 50nm,the dispersion was uniform,and the agglomeration phenomenon was relatively less.The stability of the emulsion could be up to six months..Secondly,the coating and the paint film were prepared under UV-LED curing condition.The coating and paint film with different AESO content,-OH/-NCO ratio,DMPA content,different functionality and PETA content were analyzed by infrared analysis,mechanical property analysis,thermal performance analysis,drying time analysis and film performance test.The maximum tensile strength and elongation at break of the obtained coating film were 27.53MPa and 26.35%,respectively.Due to the appearance of microphase separation,the film had two Tg.Its thermal decomposition was divided into three stages,and the thermal stability was good.The pencil hardness of the paint film could reach 6H,the adhesion was level 1,and the thickness of the paint film was between 80-100?m.The obtained emulsion could realize the rapid curing of the coating for 10s on the wood surface.Finally,in order to further improve the mechanical properties of the coating,cellulose nanofibers were added to modify it.And the effects of two ways of physical mixing and prepolymer on the properties of emulsion and film were explored.The effects of different proportion of cellulose nanofibers on the properties of emulsion and film were investigated.After adding cellulose nanofibers,the mechanical properties increased from 27.53MPa to 32.07MPa,an increase of about 17%,and the elongation at break increased from 26.35%to about 30%,an increase of about 15%.With the help of infrared analysis,water contact angle analysis,thermal performance analysis and paint film performance,it was determined that the addition method of prepolymer was better than in the physical blending method,the optimal addition amount of cellulose nanofibers under the two addition methods was 2%and 3%,respectively.The UV-LED curing epoxy soybean oil-based WPUA wood coatings were successfully prepared.This coating has the advantages of fast curing speed,good storage stability and better mechanical properties.It has certain reference significance for the environmental protection transformation and development of wood coatings.