Method of drying substrates and use thereof

Abstract

A method is provided for washing, drying, applying a curable coating, and effecting the cure of such coating on a variety of substrates, such as metal, for example steel, plastic and wood. A particularly effective drying procedure based on the generation of a dehumidified and filtered air stream directed substantially parallel to the wet substrate allows for a significant decrease in drying time while maintaining coating effectiveness.

What is claimed is:  
     
         1 . A drying method for expeditiously effecting water removal from an exposed wet surface of a substrate selected from the group consisting of metal, plastic or wood, which drying method utilizes a drying system comprising a drying booth to receive wet substrate in a batchwise or continuous manner, and means for continuously generating and circulating within the drying booth, a dehumidified and filtered air stream having an RH value of at least about 9% at temperature up to 105° F., which is directed in a substantially parallel manner at a rate of at least 50 ft per minute across the substrate surface in the drying booth.  
     
     
         2 . A drying method in accordance with    claim 1   , where water is expeditiously removed from an exposed wet surface of steel.  
     
     
         3 . A drying method in accordance with    claim 1   , where dry steel substrate is electrostaticly coated with charged powder which is thereafter cured.  
     
     
         4 . A drying method in accordance with    claim 1   , where dry steel substrate is painted with an aqueous based air curable paint.  
     
     
         5 . A drying method in accordance with    claim 1   , where a dry thermoset plastic substrate is powder coated in accordance with the method of    claim 1   .  
     
     
         6 . A drying method in accordance with    claim 1   , where a dry thermoset plastic substrate is a polyimide.  
     
     
         7 . A method for coating a substrate selected from the group consisting of metal, plastic and wood in a stepwise manner, which comprises: 
 (1) washing the substrate;    (2) drying the substrate;    (3) coating the substrate with a curable material selected from the group consisting of a heat curable powder coating composition and an air curable aqueous based paint; and    (4) effecting the cure of the curable material on the substrate;    wherein the drying of the substrate in step (2), utilizes a drying system comprising a drying booth to receive wet substrate in a batchwise or continuous manner, and means for continuously generating and circulating within the drying booth, a dehumidified and filtered air stream having an RH value of at least about 9% at temperature up to about 105° F., which is directed in a substantially parallel manner at a rate of at least 50 ft per minute across substrate surface in the drying booth.    
     
     
         8 . A wooden substrate washed, dried, painted, and allowed to air dry in accordance with    claim 7   .  
     
     
         9 . A steel substrate washed, dried, painted, and allowed to air dry in accordance with    claim 7   .  
     
     
         10 . A plastic substrate washed, dried, painted, and allowed to air dry in accordance with    claim 7   .  
     
     
         11 . A steel substrate washed, dried and powder coated in accordance with    claim 7   .