Study On The Surface Electric Resistance Of Wooden Doors Decorated By Decorative Veneer Based On Electrostatic Spraying

Electrostatic spraying technology is widely used in automobile,ship,aviation and other fields,which has the characteristics of high efficiency,high coating efficiency,good coating quality and low pollution.With the development of electrostatic spraying technology,the surface conductivity of poor material can also be used for electrostatic spray coating.In recent years,the application of electrostatic spraying on the surface finishing of wood products is also increasing.At present,spinning bell electrostatic spray is mainly used for the coating of work-piece with large plane at home and abroad.Electrostatic spraying technology for wooden door has become a hot and difficult point in the research of wood products electrostatic spraying technology at home and abroad because the wooden door area is large with irregular part with convex concave and its surface conductivity is poor.The related research shows that the surface resistance of wooden doors will directly affect the effect of electrostatic spraying,the larger the surface resistance,the worse the effect of electrostatic spraying.Wood composite door is the study object in this thesis.The resistance of decorative veneer in the surface layer of wood composite door,adhesive,medium density fiberboard(MDF),paint and surface resistance of wooden door decorated by decorative veneer before or after coating are studied systematically.The influences of moisture content,measured length,texture,timber species and thickness on decorative veneer surface resistance are studied.The relationship between surface resistance of wooden door decorated by decorative veneer,timber species,texture and measured length is discussed.The influences of paint film thickness,timber species,texture and measured length on surface resistance of wooden door are studied.Experimental results show that:1.The moisture content has a significant effect on the surface resistance of the decorative veneer,the greater the moisture content,the smaller the surface resistance of the four kinds of decorative veneer include Black walnut,Sapele,Teak and Oak in any direction of measurement.The surface resistance of the decorative veneer is greater when the moisture content is less than 14%.The surface resistance of the decorative veneer is smaller when the moisture content is between 14% and 20%.In the same moisture content,the surface resistance is increased with the measured length,Black walnut has the most significant changes.The resistance is increased with the thickness of decorative veneer,Teak has the most significant changes.The surface resistance of any decorative veneer in transverse direction is larger than that in longitudinal direction.2.The resistances of adhesive and decorative veneer all have effect on the surface resistance of wooden door.The surface resistance of wooden door decorated by decorative veneer is between the resistance of adhesive and decorative veneer.The surface resistance of wooden door can be reduced by reducing adhesive resistance.When humidity is 66.2%,temperature is 25.7℃ and measured length is 52.5cm,the resistance of Black walnut decorative veneer,adhesive and MDF is 4.12×109?,2.32×103? and 5.25×108?.The surface resistance of wooden door decorated by decorative veneer is 4.42×108?.Therefore,the surface resistance of wooden door can be changed by changing the resistances of adhesive and decorative veneer.3.The surface resistance wooden door decorated by Black walnut,golden teak and Sapele decorative veneer is increased with the measured length In the process of electrostatic spraying.The surface resistance of wooden door in transverse direction is larger than that in longitudinal direction.The surface resistance of wooden door is decreased with paint film thickness(20μm、40μm、60μm).The surface resistance of wooden door has increased sharply after the coating is dried.