Method for preparing a latex with photochromic properties and uses thereof, particularly in ophthalmology

Abstract

This invention relates to a method for preparing a photochromic latex, photochromic thin films obtained therefrom, and articles coated with such thin films, in particular photochromic ophthalmic lenses.

1 - 23 . (canceled)  
   
   
       24 . A method for preparing a latex with photochromic properties comprising: 
 preparing an aqueous emulsion (I) of a composition A comprising: 
 at least one organic monomer Z, wherein said at least one monomer is further defined as comprising a C═C group and being capable of free-radical polymerization, and  
 one or more organic photochromic compounds containing a nucleus of formula:  
                     
  and  
   polymerizing composition A in the presence of a water-soluble initiator to obtain particles of an at least partially polymerized latex with photochromic properties.    
   
   
       25 . The method of  claim 24 , wherein the water-soluble initiator 
 (i) is introduced progressively to the aqueous emulsion (I), during the polymerization, or    (ii) and the aqueous emulsion (I) are each introduced progressively into a reaction medium throughout polymerization, or    (iii) is an alkali or ammonium persulfate.    
   
   
       26 . The method of  claim 25 , wherein the water-soluble initiator is introduced progressively to the aqueous emulsion I, during the polymerization.  
   
   
       27 . The method of  claim 25 , wherein the water-soluble initiator and the aqueous emulsion (I) are each introduced progressively into a reaction medium throughout polymerization.  
   
   
       28 . The method of  claim 25 , wherein the water-soluble initiator is an alkali or ammonium persulfate.  
   
   
       29 . The method of  claim 25 , wherein the water-soluble initiator is potassium or sodium persulfate.  
   
   
       30 . The method of  claim 24 , wherein the least one monomer Z is a low Tg monomer which leads to a homopolymer the glass transition temperature of which is less than or equal to 0° C.  
   
   
       31 . The method of  claim 30 , wherein the low Tg monomer represents at least 40% by weight of the monomers capable of free-radical polymerization.  
   
   
       32 . The method of  claim 24 , wherein a substrate comprises a film of the latex and wherein the substrate comprises an anti-abrasion coating on the latex film, or an anti-reflection coating on the latex film, or an anti-abrasion coating on the latex film and an anti-reflection coating on the anti-abrasion coating.  
   
   
       33 . The method of  claim 32 , wherein the substrate comprises an anti-abrasion coating.  
   
   
       34 . The method of  claim 32 , wherein the substrate comprises an anti-reflection coating.  
   
   
       35 . The method of  claim 32 , wherein the substrate comprises an anti-abrasion coating on the latex film and an anti-reflection coating on the anti-abrasion coating.  
   
   
       36 . The method of  claim 32 , wherein the substrate is an ophthalmic lens.  
   
   
       37 . The method of  claim 24 , wherein composition A comprises only one type of organic monomer Z.  
   
   
       38 . The method of  claim 24 , wherein composition A comprises more than one type of organic polymer Z.  
   
   
       39 . The method of  claim 24 , wherein the latex is a fully polymerized latex.  
   
   
       40 . The method of  claim 24 , wherein the latex is a partially polymerized latex.  
   
   
       41 . The method of  claim 24 , wherein the percentage by weight of the initiator with respect to total organic weight of monomer or monomers capable of free-radical polymerization used for the preparation of the latex is between 0.1 and 1%.  
   
   
       42 . The method of  claim 24 , wherein the organic monomer Z is an alkyl (meth)acrylate monomer.  
   
   
       43 . The method of  claim 24 , wherein the particles of the latex are further defined as having a diameter of 50 to 400 nm.  
   
   
       44 . The method of  claim 24 , wherein a dry extract of the latex represents from 30 to 50% of the total weight of the latex.  
   
   
       45 . The method of  claim 24 , wherein the pH of the latex is between 5 and 7.  
   
   
       46 . A latex with photochromic properties, further defined as comprising particles of a polymer material resulting from the free-radical polymerization of at least one monomer Z with a C═C group comprising one or more organic photochromic compound comprising a nucleus of formula:  
     
       
         
         
             
             
         
       
     
     the particles of said polymer material having an average size of between 50 and 400 nm.  
   
   
       47 . The latex of  claim 46 , wherein the particles are further defined as having an average size of between 80 and 300 nm.  
   
   
       48 . The latex of  claim 47 , wherein the particles are further defined as having an average size between 150 and 250 nm.  
   
   
       49 . The latex of  claim 46 , wherein the organic photochromic compound is further defined as not containing an indoline ring.  
   
   
       50 . The latex of  claim 46 , wherein a dry extract of the latex represents from 30 to 50% of the total weight of the latex.  
   
   
       51 . A substrate comprising a dry latex film with photochromic properties, the latex further defined as comprising particles of a polymer material resulting from the free-radical polymerization of at least one monomer Z with a C═C group comprising one or more organic photochromic compound comprising a nucleus of formula:  
     
       
         
         
             
             
         
       
     
     the particles of said polymer material having an average size of between 50 and 400 nm.  
   
   
       52 . The substrate of  claim 51 , wherein the film has a thickness of between 3 and 20 μm.  
   
   
       53 . The substrate of  claim 51 , further defined as comprising an anti-abrasion coating.  
   
   
       54 . The substrate of  claim 51 , further defined as comprising an anti-reflection coating.  
   
   
       55 . The substrate of  claim 51 , further defined as comprising an anti-abrasion coating on the latex film and an anti-reflection coating on the anti-abrasion coating.  
   
   
       56 . The substrate of  claim 51 , further defined as an ophthalmic lens.  
   
   
       57 . The method of  claim 43 , wherein the particles of the latex are further defined as having an average size of between 80 and 300 nm.  
   
   
       58 . The method of  claim 57 , wherein the particles are further defined as having an average size between 150 and 250 nm.  
   
   
       59 . The method of  claim 24 , wherein the organic photochromic compound is further defined as not containing an indoline ring.  
   
   
       60 . The method of  claim 24 , wherein the latex is further defined as a dry latex film.  
   
   
       61 . The method of  claim 60 , wherein the dry latex film has a thickness of between 3 and 20 μm.  
   
   
       62 . The method of  claim 24 , wherein a substrate comprises the latex.  
   
   
       63 . The method of  claim 62 , wherein the substrate is further defined as an ophthalmic lens.