Method of surface treatment for lens of vehicle lamp

Abstract

A method of surface treatment for a lens of a vehicle lamp. The method comprises forming a hard coating film on a outer surface of the lens by heating to harden after the hard coating film is applied onto the outer surface of the lens; cooling the lens formed with the hard coating film until the inner surface of the lens has a predetermined temperature; and forming a antifogging coating film on a inner surface of the lens by heating to dry after the antifogging coating film is applied onto the inner surface of the lens.

What is claimed is:  
     
         1 . A method of surface treatment for a lens of a vehicle lamp, said method comprising: 
 forming a hard coating film on a outer surface of the lens by heating to harden after the hard coating film is applied onto the outer surface of the lens;    cooling the lens formed with the hard coating film until the inner surface of the lens has a predetermined temperature; and    forming a antifogging coating film on a inner surface of the lens by heating to dry after the antifogging coating film is applied onto the inner surface of the lens.    
     
     
         2 . The method of surface treatment according to    claim 1   , wherein forming a hard coating film, cooling the lens, and forming a antifogging coating film are conducted in the same clean room.  
     
     
         3 . The method of surface treatment according to    claim 2   , wherein the predetermined temperature is set at temperatures higher than the room temperature of said clean room.  
     
     
         4 . The method of surface treatment according to    claim 3   , the predetermined temperature is set at 35° C. or lower.  
     
     
         5 . The method of surface treatment according to    claim 1   , the thickness of the antifogging coating film is set at 10 μm or less.  
     
     
         6 . The method of surface treatment according to    claim 1   , wherein a time interval between the completion of applying the antifogging coating film and the commencement of drying the antifogging coating film by heating is shortened stepwise in response to a rise in humidity.  
     
     
         7 . The method of surface treatment according to    claim 1   , the temperature is maintained from 110° C. to 130° C. during forming the antifogging coating film of the lens by heating to dry.  
     
     
         8 . The method of surface treatment according to    claim 1   , wherein the antifogging coating film includes a compound of a hydrophilic portion with a hydrophobic portion.  
     
     
         9 . The method of surface treatment according to    claim 8   , wherein the hydrophobic portion of the compound in the antifogging coating film sticks to the inner surface of the lens.  
     
     
         10 . The method of surface treatment according to    claim 1   , wherein the lens is made of plastic.