Colorants for use in tinted contact lenses and methods for their production

Abstract

The invention provides a colorant for use in tinting contact lenses in which the binding polymer used is capable of forming an interpenetrating polymer network with the lens material. When the colorants of the invention are applied to uncured lens material that is subsequently cured, the binding polymer forms an interpenetrating polymer network with the lens material embedding the colorant within the lens material resulting in a stable, tinted lens.

What is claimed is:  
     
         1 . A colorant for use in tinting contact lenses, the colorant comprising one or more pigments, one or more solvents, and a binding polymer, wherein the binding polymer is capable of forming an interpenetrating polymer network with a lens material.  
     
     
         2 . The colorant of  claim 1 , wherein the binding polymer comprises a molecular weight of about 7,000 to about 40,000.  
     
     
         3 . The colorant of  claim 1 , wherein the binding polymer comprises: 
       CH 3 (CH 2 ) x —L—COCHR═CH 2   wherein L is —NH or oxygen, x is a whole number from 2 to 24, R is a C 1  to C 6  alkyl or hydrogen.    
     
     
         4 . The colorant of  claim 1 , wherein the binding polymer comprises a copolymer of methacrylic acid, 2-hydroxyethyl methacrylate, and lauryl methacrylate.  
     
     
         5 . The colorant of  claim 1 , wherein the binding polymer comprises a homopolymer of 2-hydroxyethyl methacrylate.  
     
     
         6 . The colorant of  claim 1 ,  2 ,  4  or  5 , wherein the one or more solvents comprises two medium boiling point solvents and one low boiling point solvent.  
     
     
         7 . The colorant of  claim 4 , wherein the medium boiling point solvents comprise 1-ethoxy-2-propanol and isopropyl lactate.  
     
     
         8 . The colorant of  claim 1 ,  2 ,  4  or  5 , further comprising a plasticizer and an opacifying agent.  
     
     
         9 . The colorant of  claim 8 , comprising about 0.25 to about 25 weight percent of the one or more pigments, about 30 to about 45 weight percent of the binding polymer, about 40 to about 70 weight percent of the one or more solvents, about 0 to about 25 weight percent of the opacifying agent, and about 0.25 to about 7 weight percent of the plasticizer.  
     
     
         10 . A colorant for use in tinting contact lenses, the colorant comprising one or more pigments, one or more solvents, and a binding polymer having a molecular weight of about 7,000 to about 40,000, wherein the binding polymer is capable of forming an interpenetrating polymer network with a lens material comprising etafilcon A.  
     
     
         11 . The colorant of  claim 10 , wherein the binding polymer comprises a copolymer of methacrylic acid, 2-hydroxyethyl methacrylate, and lauryl methacrylate.  
     
     
         12 . The colorant of  claim 10 , wherein the binding polymer comprises a homopolymer of 2-hydroxyethyl methacrylate.  
     
     
         13 . The colorant of  claim 10 ,  11  or  12 , wherein the one or more solvents comprises two medium boiling point solvents and one low boiling point solvent.  
     
     
         14 . The colorant of  claim 13 , wherein the two medium boiling point solvents comprise 1-ethoxy-2-propanol and isopropyl lactate.  
     
     
         15 . The colorant of  claim 10 ,  11  or  12 , further comprising a plasticizer and an opacifying agent.  
     
     
         16 . The colorant of  claim 15 , comprising about 0.25 to about 25 weight percent of the one or more pigments, about 30 to about 45 weight percent of the binding polymer, about 40 to about 70 weight percent of the one or more solvents, about 0 to about 25 weight percent of the opacifying agent, and about 0.25 to about 7 weight percent of the plasticizer.  
     
     
         17 . A method for manufacturing a tinted contact lens comprising the steps of: a.) applying to a molding surface of a mold a tinting-effective amount of a colorant comprising one or more pigments, one or more solvents and a binding polymer; b.) dispensing a lens-forming amount of a lens material into the mold; c.) swelling the colorant in the lens material; and c.) curing the lens material in the mold to form the tinted contact lens, wherein the binding polymer and the lens material form an interpenetrating polymer network.  
     
     
         18 . The method of  claim 17 , wherein the binding polymer has a molecular weight of about 7,000 to about 40,000 and the lens material comprises etafilcon A.  
     
     
         19  The method of  claim 18 , wherein the binding polymer comprises a copolymer of methacrylic acid, 2-hydroxyethyl methacrylate, and lauryl methacrylate.  
     
     
         20 . The method of  claim 18 , wherein the binding polymer comprises a homopolymer of 2-hydroxyethyl methacrylate.  
     
     
         21 . The method of  claim 17  or  18 , wherein the one or more solvents comprises two medium boiling point solvents and one low boiling point solvent.  
     
     
         22 . The method of  claim 21 , wherein the two medium boiling point solvents comprise 1-ethoxy-2-propanol and isopropyl lactate.  
     
     
         23 . A mold for use in manufacturing a tinted contact lens comprising a first and second mold half, wherein at least one molding surface of the first and second mold halves comprises one or more pigments, one or more solvents, and a binding polymer, wherein the binding polymer is capable of forming an interpenetrating polymer network with a lens material.  
     
     
         24 . The mold of  claim 23 , wherein the binding polymer has a molecular weight of about 7,000 to about 40,000.  
     
     
         25 . The mold of  claim 23 , wherein the binding polymer comprises a copolymer of methacrylic acid, 2-hydroxyethyl methacrylate, and lauryl methacrylate.  
     
     
         26 . The mold of  claim 23 , wherein the binding polymer comprises a homopolymer of 2-hydroxyethyl methacrylate.  
     
     
         27 . The mold of  claim 25  or  26 , wherein the one or more solvents comprises two medium boiling point solvents and one low boiling point solvent.  
     
     
         28 . The mold of  claim 27 , wherein the two medium boiling point solvents comprise 1-ethoxy-2-propanol and isopropyl lactate.