Studies On The Veneer-overlaying Process And Painting Process Of Waterborne Wood Coats On Poplar-based Panels For Furniture

Veneer-overlaying process of multi-layer plywood and painting process of waterborne wood coats on the veneered-panels for furniture were investigated in the order of process in the dissertation,and the latter was core.Maple and Red oak veneers were tried to overlay on poplar plywood,and a waterborne coating binder system,i.e.,styrene-acrylic sealer,acrylic primer, and acrylic-polyurethane top coat,was specifically investigated.Resin content was vital to penetration rate of urea formaldehyde(UF)through overlaid maple veneers,and was as well influential to warping degree of maple-overlaid plywood. Hot-pressing period played an evident role on shrinkage coefficients of veneered panels in width.The results showed that bi-component adhesive content was important to penetration rate through red-oak veneer,hot-pressing pressure affected evidently warping degree,and flour addition was important to shrinkage coefficients of veneered panels in width.It was found that adhesion of coatings was evidently affected by surface sanding quality of veneered panel,spraying content of sealer,and painting times of sealer and top coat.Top coat was important to degree of light of coatings.Humidity(50%to70%)played an more important role than temperature(35℃to 55℃)on paint drying speed.With increasing humidity,paint drying speed decreased.It was also proved that the effect of humidity was more important than temperature on drying process of waterborne coats.In drying practices,humidity should be controlled strictly to waterborne coat.Veneered panel should be sanded to surface roughness of 5.20 micron,then was painted two times of sealer,primer,and top coat.For sealer,painting content was 60g/m~2 each time,and for primer and top coat,the content was 100g/m~2 and 120g/m~2,respectively.At a ventilation velocity of 0.3m/s,the optimum hot-air-drying processes were:The first sealer should be applied and dried at 55℃,50%relative humidity(RH)for 6.5 minutes,then followed by the second sealer dried for 9 minutes;The first primer should be applied and dried at 35℃,50%RH for 16 minutes,followed by the second primer drying for 22 minutes;The first top coat was applied and dried at 35℃,70%RH for 50 minutes,followed by a second top coat drying for 40 minutes.The hot-air-drying processes of wet-dry and wet-wet coats were beneficial to factory seasoning of waterborne coats.