Method of making a thermoplastic-based article and a thermoplastic-based article made thereby

Abstract

A lens article containing a photochromic substance, such as a photochromic dye, having a minimum degradation temperature arranged relative to a substrate, such as by being incorporated into the substrate. The substrate is formed from a blend of first and second thermoplastic polymers. The first polymer has a glass transition temperature higher than the minimum degradation temperature of the photochromic substance. The second polymer is blended with the first polymer to provide the substrate with an adjusted glass transition temperature lower than the minimum degradation temperature. This allows the combined photochromic substance and substrate to be thermoformed at a temperature greater than or equal to the adjusted glass transition temperature but below the minimum degradation temperature so that the photochromic substance is not degraded during fabrication of the lens article.

1 . A method of making a photochromic lens article, comprising: 
 a) providing at least one photochromic substance in operable relationship with a substrate, the photochromic substance having a minimum degradation temperature;    b) forming the substrate as a polymer blend that contains a first polymer having a first glass transition temperature higher than said minimum degradation temperature, said polymer blend having a second glass transition temperature lower than said minimum degradation temperature; and    c) thermoforming the substrate and at least one photochromic substance at a temperature below said minimum degradation temperature so as not to degrade the at least one photochromic substance.    
   
   
       2 . A method according to  claim 1 , wherein the photochromic substance includes at least one such substance selected from the group comprising: naphthopyrans, spironapthopyrans, fulgides, fulgimides, salicylates, triazoles, oxazoles, azobenzenes and silver halide.  
   
   
       3 . A method according to  claim 1 , including supporting the photochromic substance adjacent the substrate using a filtering layer.  
   
   
       4 . A method of  claim 3 , including providing at least one protective layer adjacent the filtering layer.  
   
   
       5 . A method of  claim 4 , wherein the filtering layer includes at least one of CAB, polypropylene, poly(vinyl chloride) and poly(vinyl acetate).  
   
   
       6 . A method of  claim 1 , wherein step b) includes forming said polymer blend by blending a second polymer with the first polymer in a predetermined amount that lowers said first glass transition to said second glass transition temperature.  
   
   
       7 . A method of  claim 1 , wherein the at least one photochromic substance is incorporated into the substrate.  
   
   
       8 . A method according to  claim 7 , wherein the at least one photochromic substance includes a photochromic dye.  
   
   
       9 . A method according to  claim 1 , wherein step c) includes thermoforming the substrate and at least one photochromic substance into one of an ophthalmic lens and a pre-contoured ophthalmic lens insert.  
   
   
       10 . A method according to  claim 1 , wherein the step b) of forming the substrate as a polymer blend is performed prior to the step a) of providing and supporting the least one photochromic substance in operable relationship with the substrate.  
   
   
       11 . A method of making a photochromic lens article that includes a substrate and at least one photochromic substance having a minimum degradation temperature, the method comprising: 
 a) forming the substrate by: 
 i) providing a first polymer having a first glass transition temperature higher than the minimum degradation temperature; and  
 ii) blending a second polymer with said first polymer to form a blended polymer having a second glass transition temperature lower than said minimum degradation temperature;  
   b) placing the at least one photochromic substance in operable relationship to the substrate; and    c) thermoforming the at least photochromic substance and the substrate at a temperature lower than said minimum degradation temperature so as to form said photochromic lens article while avoiding degrading the at least one photochromic substance.    
   
   
       12 . A method according to  claim 11 , including supporting the at least one photochromic substance in a filter layer  
   
   
       13 . The method of  claim 12 , including sandwiching the filter layer between two protective layers.  
   
   
       14 . A method according to  claim 11 , wherein the first polymer includes at least one of a carbonate polymer and an acrylic polymer  
   
   
       15 . A method according to  claim 12 , wherein the at least one photochromic substance includes a photochromic dye.  
   
   
       16 . A method according to  claim 12 , wherein the at least one photochromic substance is incorporated into the substrate.  
   
   
       17 . A photochromic lens article, comprising: 
 a) at least one photochromic substance having a minimum degradation temperature; and    b) a substrate arranged in working relation with the at least one photochromic substance, said substrate comprising a blend of a first polymer and a second polymer, said first polymer having a first glass transition temperature greater than the minimum degradation temperature, the second polymer selected to cause the blended-polymer substrate to have a second glass transition temperature lower than said minimum degradation temperature so that the at least one photochromic substance and the substrate are thermoformable at a temperature lower than the minimum degradation temperature so as not to degrade the at least one photochromic substance when forming the lens article.    
   
   
       18 . The lens article of  claim 17 , wherein the at least one photochromic substance includes a photochromic dye.  
   
   
       19 . The lens article of  claim 17 , wherein the at least one photochromic substance is incorporated into the substrate.  
   
   
       20 . The lens article of  claim 17 , wherein said first polymer is a poly(methyl methacrylate) and said second polymer is a butyldyene.