The Study Of 2K WPU Wood Coating Preparation And Modification

Two packed waterborn polyurethane?2K WPU?was selected as the research object of wood varnish waterborn coating in this article.Improving the quality of 2K WPU coating film and the adaptability of coating process were considered as the research target.In this paper,improving the film forming material primary reaction degree,ameliorating the liquid surface properties,reducing the side effects,enhancing the wettability of solid wood base material,improving the storage stability,lowing foamability of coating and improving the coating mechanical properties were achieved by controlling the 2K WPU main forming material reaction process,2K WPU coating and 2K dispersion properties of 2K WPU coating.In this article,there are several conclusions vertificated through the experiment:?1?In the preparation of 2K WPU coatings prepolymers aggregation stage,primary reaction,liquid viscosity,the gas content in liquid and the efficiency of dispersion for modification direction were optimized by changing the reaction temperature,ratio of pre polymers and mixing process,the preparation of 2K WPU dispersion.?2?In 2K WPU coating low foaming process optimization,lower liquid viscosity,higher in wettability on the surface of the solid wood base material for blister and low solid film modified direction were achieved by changing the mixing process,defoaming agent formula,drying way of curing process.The optimized process parameters are as follows:the isocyanate and polyol hydroxyl were added as the amount of substance ratio of 1.2:1 in reaction temperature is 25?.Then mixing center gradually lifted from the bottom of mixing bottle.And stirring speed of 850 r/min,mixing process of dispersed under the condition of 120 min of 2K WPU dispersion.Adding the quality percentage of5%¹%water,1%of wetting agent Sago-3645,flow ping agent Sago-3380 and 1%organic silicon defoamer Sago-1710.Next,coating the 2K WPU by wire rod coating machine according to 50g·m^-2 coating weight coating in the substrate surface.Then the 2K WPU wet coating film was drying at 30?environment temperature using far infrared drying oven drying 4 h.?3?In the nano cellulose fiber modified 2K WPU coatings experiments,it was shown that:adhesion,water resistance and wettability of 2K WPU coating were improved by adding 20%nano cellulose crystal?CNC?to the 2K WPU coatings.Compared with the addition of CNF,CNC performanced better than the addition of 10%CNC,and it has obvious effect on the coating wettability.Compared with the addition of CNC,10%CNF of 2K WPU coatings was more stable.?4?In the nano silica sol modified 2K WPU coatings experiments,it was shown that:the 2K WPU coating flexibility,adhesion,water resistance and mechanical properties were improved by add 5%nano silica sol.