Merchandisers having anti-fog coatings and methods for making the same

Abstract

A variety of refrigerators and merchandisers having glass or plastic substrates that are substantially fog-resistant are provided. For example, refrigerator doors having a substantially transparent substrate including an anti-fog coating on at least a portion thereof are provided. The portion of the substrate may substantially not fog when the portion has an initial surface temperature and is then exposed to a moist air ambient with a dewpoint temperature equal to or greater than the surface temperature for a period of time. The surface temperature may be less than about 0° C. and the period of time may be greater than about 6 seconds.

1 . A method of manufacturing a refrigerator door having a substantially transparent substrate, the method comprising the acts of: 
 mixing a blocked hexamethylene diisocyanate and a polyol to form a mixture;    applying the mixture to at least a portion of the substantially transparent substrate; and curing the mixture,    wherein the substrate is part of a refrigerator door or is used to manufacture a refrigerator door.    
     
     
         2 . The method of  claim 1 , wherein the diisocyanate is blocked by 3,5-dimethylpyrazole.  
     
     
         3 . The method of  claim 1 , wherein the polyol comprises polyalkylene glycols.  
     
     
         4 . The method of  claim 1 , wherein the blocked hexamethylene diisocyanate comprises 3,5-dimethylpyrazole blocked biuret of hexamethylene diisocyanante.  
     
     
         5 . The method of  claim 1 , wherein the blocked hexamethylene diisocyanate comprises 3,5-dimethylpyrazole blocked biuret of hexamethylene diisocyanante and the polyol comprises a block polymer of polyethylene glycol and polypropylene glycol.  
     
     
         6 . The method of  claim 5 , wherein the mixture comprises about 15% to about 90% by weight 3,5-dimethylpyrazole blocked biuret of hexamethylene diisocyanate and about 10.0% to about 85.0% by weight block polymer of polyethylene glycol and polypropylene glycol.  
     
     
         7 . The mixture of  claim 6  further comprising dibutyl tin dilaurate in an amount not greater than about 2% by weight.  
     
     
         8 . The method of  claim 1 , wherein the mixture further comprises dibutyl tin dilaurate.  
     
     
         9 . The method of  claim 8 , wherein the mixture further comprises diacetone alcohol.  
     
     
         10 . The method of  claim 1 , wherein the mixture comprises about 15% to about 90% by weight blocked hexamethylene diisocyanate and about 10.0% to about 85.0% by weight polyol.  
     
     
         11 . The method of  claim 10  further comprising dibutyl tin dilaurate in an amount not greater than about 2% by weight.  
     
     
         12 . The method of  claim 1 , wherein the mixture is applied to a transparent substrate having a low-emissivity surface or a low-emissivity coating thereon.  
     
     
         13 . The method of  claim 12 , wherein the low-emissivity surface or coating does not emit radiation between about 0.7 microns and about 2.7 microns.  
     
     
         14 . The method of  claim 1 , wherein the cured mixture forms a coating comprising a hydrophobic surface having a surface tension.  
     
     
         15 . The method of  claim 14 , wherein the surface tension of the hydrophobic surface is less than about 58 dynes/cm.  
     
     
         16 . The method of  claim 14 , wherein the surface tension of the hydrophobic surface is less than about 39 dynes/cm.  
     
     
         17 . The method of  claim 14 , wherein the surface tension of the hydrophobic surface is less than about 26 dynes/cm.  
     
     
         18 . The method of  claim 1 , wherein the portion of the substrate does not substantially fog when the portion has an initial surface temperature and is then exposed to a moist air ambient with a dewpoint temperature equal to or greater than the surface temperature for a period of time, wherein the surface temperature is less than about 0° C. and the period of time is greater than about 6 seconds.  
     
     
         19 . The method of  claim 18 , wherein the period of time is greater than about five minutes.  
     
     
         20 . The method of  claim 1 , wherein the portion of the substrate does not substantially fog when the portion has an initial surface temperature and is then exposed to a moist air ambient with a dewpoint temperature equal to or greater than the surface temperature for a period of time, wherein the surface temperature is less than about −18° C. and the period of time is greater than about 6 seconds.  
     
     
         21 . The method of  claim 20 , wherein the period of time is greater than about five minutes.