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. Many of the coatings exhibit color stable properties.

1 . A method of manufacturing a refrigerator door having a substantially transparent substrate, the method comprising the acts of: 
 mixing an isocyanate with a polyol to form a mixture;    applying the mixture to at least a portion of the substantially transparent substrate; and    curing the mixture to form a coating, the coating showing a change in L* of less than about 10.0, a change in a* of less than about 1.2, and a change in b* of less than about 6.0, when the coating is exposed to fluorescent light having a radiant intensity of 0.05 mw/cm 2  over a period of greater than 5 days, wherein, using CIELAB values, L* measures the psychometric lightness of a coating, an L* value of 100 indicating clear and a value of 0 indicating black, a* measures the color of the coating as referenced against a red(+) and green(−) axis, and b* measures the color of the coating as referenced against a yellow(+) and blue(−) axis,    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 isocyanate comprises at least one of ε-caprolactam blocked toluene diisocyanate, 3,5-dimethylpyrazole blocked toluene diisocyanate, 3,5-dimethylpyrazole blocked IPDI, 3,5-dimethylpyrazole blocked IPDI trimer, 3,5-dimethylpyrazole blocked hexamethylene diisocyanate biuret, diethyl malonate blocked hexamethylene diisocyanate biuret, ε-caprolactam blocked hexamethylene diisocyanate trimer, 3,5-dimethylpyrazole blocked hexamethylene diisocyanate trimer, methylethylketoxime blocked hexamethylene diisocyanate trimer, 3,5-dimethylpyrazole and diethyl malonate blocked IPDI trimer, 3,5-dimethylpyrazole and diethyl malonate blocked hexamethylene diisocyanate biuret, 3,5-dimethylpyrazole, diethyl malonate blocked hexamethylene diisocyanate trimer and a combination thereof.  
     
     
         3 . The method of  claim 1 , wherein the isocyanate comprises 3,5-dimethylpyrazole blocked hexamethylene diisocyanate biuret.  
     
     
         4 . The method of  claim 1 , wherein the polyol comprises one or more tetrahydroxy functional copolymers of ethylene oxide and propylene oxide.  
     
     
         5 . The method of  claim 1 , wherein the mixture comprises about 51 to 66% by weight hexamethylene diisocyanate and about 20 to 37% by weight of polyol.  
     
     
         6 . The method of  claim 1 , wherein the isocyanate comprises 3,5-dimethylpyrazole blocked hexamethylene diisocyanate and the polyol comprises tetrahydroxy functional copolymers of ethylene oxide and propylene oxide.  
     
     
         7 . The method of  claim 1 , wherein the change in L* is less than about 0.05, the change in a* is less than about 0.15, and the change in b* is less than about 0.25.  
     
     
         8 . The method of  claim 7 , wherein the period is greater than 30 days.  
     
     
         9 . The method of  claim 1 , wherein the period is greater than 30 days.  
     
     
         10 . A refrigerator door comprising a substantially transparent substrate having an anti-fog coating on at least a portion thereof, the coating showing a change in L* of less than about 10.0, a change in a* of less than about 1.2, and a change in b* of less than about 6.0, when the coating is exposed to fluorescent light having a radiant intensity of 0.05 mw/cm 2  over a period of greater than 5 days, wherein, using CIELAB values, L* measures the psychometric lightness of a coating, an L* value of 100 indicating clear and a value of 0 indicating black, a* measures the color of the coating as referenced against a red(+) and green(−) axis, and b* measures the color of the coating as referenced against a yellow(+) and blue(−) axis.  
     
     
         11 . The refrigerator door of  claim 10 , wherein the change in L* is less than about 5.0, the change in a* is less than about 0.6, and the change in b* is less than about 3.0.  
     
     
         12 . The refrigerator door of  claim 10 , wherein the change in L* is less than about 2.5, the change in a* is less than about 0.3, and the change in b* is less than about 1.5.  
     
     
         13 . The refrigerator door of  claim 10 , wherein the change in L* is less than about 1.25, the change in a* is less than about 0.15, and the change in b* is less than about 0.75.  
     
     
         14 . The refrigerator door of  claim 10 , wherein the change in L* is less than about 0.65, the change in a* is less than about 0.15, and the change in b* is less than about 0.5.  
     
     
         15 . The refrigerator door of  claim 10 , wherein the change in L* is less than about 0.1, the change in a* is less than about 0.15, and the change in b* is less than about 0.25.  
     
     
         16 . The refrigerator door of  claim 10 , wherein the change in L* is less than about 0.05, the change in a* is less than about 0.15, and the change in b* is less than about 0.25.  
     
     
         17 . The refrigerator door of  claim 10 , wherein the period is greater than 10 days.  
     
     
         18 . The refrigerator door of  claim 10 , wherein the period is greater than 15 days.  
     
     
         19 . The refrigerator door of  claim 10 , wherein the period is greater than 20 days.  
     
     
         20 . The refrigerator door of  claim 10 , wherein the period is greater than 25 days.  
     
     
         21 . The refrigerator door of  claim 10 , wherein the period is greater than 30 days.  
     
     
         22 . The refrigerator door of  claim 16 , wherein the period is greater than 10 days.  
     
     
         23 . The refrigerator door of  claim 16 , wherein the period is greater than 15 days.  
     
     
         24 . The refrigerator door of  claim 16 , wherein the period is greater than 20 days.  
     
     
         25 . The refrigerator door of  claim 16 , wherein the period is greater than 25 days.  
     
     
         26 . The refrigerator door of  claim 16 , wherein the period is greater than 30 days.  
     
     
         27 . The refrigerator door of  claim 16 , wherein the coating is formed by curing a mixture comprising hexamethylene diisocyanate and one or more tetrahydroxy functional copolymers of ethylene oxide and propylene oxide.  
     
     
         28 . The refrigerator door of  claim 27 , wherein the hexamethylene diisocyanate comprises a 3,5-dimethylpyrazole blocked hexamethylene diisocyanate.