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 diisocyanate. 
   
   
       5 . The method of  claim 1 , wherein the blocked hexamethylene diisocyanate comprises 3,5-dimethylpyrazole blocked biuret of hexamethylene diisocyanate 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 method of  claim 6 , wherein the mixture further comprises 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 , wherein the mixture further comprises 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. 
   
   
       22 . The method of  claim 1 , wherein the polyol comprises a tetrahydroxy functional copolymer comprising ethylene oxide, propylene oxide or a combination thereof. 
   
   
       23 . The method of  claim 1 , wherein the coating comprises a surfactant in an amount of less than about 3%. 
   
   
       24 . The method of  claim 1 , wherein the cured mixture forms a coating comprising a hydrophobic surface having a surface tension and a hydrophilic interior having a hydrophilicity.