Optically clear reinforced silicone elastomers of high optical refractive index and improved mechanical properties for use in intraocular lenses

Abstract

Optically clear, reinforced cross-linked silicone elastomers of the invention contain 12 to 18 mol percent of aryl substituted siloxane units of the formula R 4 ,R 5 —SiO, end blockers containing silioxane units of the formula R 1 R 2 R 3 —Si—O, and dialkyl siloxane units of the formula R 6 R 7 —Si—O R 1 and R 2 are alkyl, aryl or substituted alkyl or substituted aryl groups, and R 3 is an alkenyl group. R 4 and R 5 are phenyl or mono lower alkyl substituted phenyl groups. R 6 and R 7 are methyl or ethyl groups. The polymer has a degree of polymerization between 100 to 2000, and preferably approximately 250. The polymer also contains trimethyl silyl treated silica as a reinforcer in the weight ratio of approximately 15 to 45 parts of reinforcer to 100 parts of the polymer. After cross-linking, the polymer has properties of an optical refractive index which is at least 1.44, a type A durometer hardness of at least 35, tensile strength of at least 500 psi and tear strength of at least 20 phi. The foregoing properties render the cross-linked polymer especially suitable for forming the bodies of intraocular lenses.

What is claimed is:  
     
         1 . An optically clear, reinforced cross-linked silicone elastomer, comprising: 
 a polymer containing 12 to 18 mol percent diphenyl siloxane units, and end blockers containing siloxane units of the formula R 1 ,R 2 ,R 3 —Si—O wherein R 1  and R 2  are alkyl, aryl or substituted alkyl or substituted aryl group, R 1  and R 2  being either identical or different from one another and wherein R 3  is an alkenyl group, the balance of the polymer consisting of dimethyl siloxane units, the polymer having a degree of polymerization approximately between 100 to 2000, and the polymer having been cured by cross linking;    a trimethyl silyl treated silica reinforcer finely dispersed in the polymer, the elastomer having the physical properties of: 
 an optical refractive index which is at least 1.44;  
 a Type A durometer hardness value of at least 35;  
 a tensile strength of at least 500 psi, and  
 a tear strength of at least 20 pli.  
   
     
     
         2 . The silicone elastomer of  claim 1  wherein the R 1  and R 2  groups of the end blocking siloxane units are methyl, and the R 3  group of the end blocking siloxane unit is vinyl.  
     
     
         3 . The silicone elastomer of  claim 2  wherein the polymer contains approximately 14 to 16 mol percent diphenyl siloxane units.  
     
     
         4 . The silicone elastomer of  claim 3  wherein the polymer contains approximately 15 mol percent diphenyl siloxane units.  
     
     
         5 . The silicone elastomer of  Claim 3  wherein the optical refractive index is at least 1.459.  
     
     
         6 . The silicone elastomer of  claim 3  wherein the ratio of polymer to the trimethyl silyl treated silica reinforcer is approximately 15 to 45 parts by weight of the reinforcer to 100 parts by weight of the polymer.  
     
     
         7 . The silicone elastomer of  claim 6  wherein the ratio of polymer to the trimethyl silyl treated silica reinforcer is approximately 27 parts of the reinforcer to 100 parts of the polymer.  
     
     
         8 . The silicone elastomer of  claim 3  having a type A durometer hardness value of approximately 38 to 40, a tensile strength of approximately 700 to 750 psi, and a tear strength of approximately 40 pli.  
     
     
         9 . The silicone elastomer of  claim 3  wherein the degree of polymerization is approximately 250 .  
     
     
         10 . An optically clear, reinforced cross-linked silicone elastomer, comprising: 
 a polymer containing 12 to 18 mol percent of aryl substituted siloxane units of the formula R 4 ,R 5 —Si—O wherein R 4  and R 5  are identical with one another or are different from one another and represent phenyl, or mono- or di- lower alkyl substituted phenyl groups, and end blockers containing siloxane units of the formula R 1 ,R 2 ,R 3 —Si—O wherein R 1  and R 2  are alkyl, aryl or substituted alkyl or substituted aryl group, R 1  and R 2  being either identical or different from one another and wherein R 3  is an alkenyl group, the balance of the polymer consisting of dialkyl siloxane units of the formula R 6 ,R 7 —Si—O wherein R 6  and R 7  are identical with one another or are different from one another and are methyl or ethyl groups, the polymer having a degree of polymerization approximately between 100 to 2000, and the polymer having been cured by cross linking;    a trimethyl silyl treated silica reinforcer finely dispersed in the polymer, the cross-linked elastomer having the physical properties of: 
 an optical refractive index which is at least 1.44;  
 a Type A durometer hardness value of at least 35;  
 a tensile strength of at least 500 psi, and  
 a tear strength of at least 20 pli.  
   
     
     
         11 . The elastomer of  claim 10  wherein the R 4  and R 5  groups are phenyl groups.  
     
     
         12 . The elastomer of  claim 10  wherein the R 1  and R 2  groups are methyl.  
     
     
         13 . The elastomer of  claim 10  wherein the R 1  And R 2  groups are methyl, the R 3  group is vinyl.  
     
     
         14 . The elastomer of  claim 10  wherein the R 6  and R 7  groups are methyl.  
     
     
         15 . The elastomer of  claim 10  wherein the degree of polymerization is approximately 250 .  
     
     
         16 . The elastomer of  claim 10  wherein the ratio of the reinforcer to the polymer is approximately 15 to 45 part per weight for 100 parts of the polymer.  
     
     
         17 . The elastomer of  claim 10  further comprising a ultra violet light absorbing agent covalently linked to the cross linked elastomer.  
     
     
         18 . An optically clear, reinforced polyayloxane base comprising: 
 a copolymer having 12 to 18 mol percent diphenyl siloxane units, and end blockers containing siloxane units of the formula R 1 ,R 2 ,R 3 —Si—O wherein R 1  and R 2  are alkyl, aryl or substituted alkyl or substituted aryl group, R 1  and R 2  being either identical or different from one another and wherein R 3  is an alkenyl group, the balance consisting of dimethyl siloxane units, the polymer having a degree of polymerization approximately between 100 to 2000;    a trimethyl silyl treated silica reinforcer finely dispersed in the copolymer, the weight ratio of the reinforcer to the copolymer being approximately 15 to 45 parts for 100 parts of the copolymer, the base having an optical refractive index of at least 1.44 and a viscosity of approximately 35,000 to 80,000 cp and is capable of being cured by cross-linking such that the physical properties of the cured cross-linked base include: 
 an optical refractive index which is at least 1.44;  
 a Type A durometer hardness value of at least 35;  
 a tensile strength of at least 500 psi, and  
 a tear strength of at least 20 pli.  
   
     
     
         19 . The base of  claim 18  wherein R 1  and R 2  are methyl, and R 3  is vinyl.  
     
     
         20 . The base of  claim 19  wherein the degree of polymerization of the copolymer is approximately 250 .  
     
     
         21 . The base of  claim 19  wherein the weight ratio of the reinforcer to the copolymer in approximately 27 parts for 100 parts of the polymer.  
     
     
         22 . The base of  claim 19  wherein the copolymer comprises approximately 15 mol percent diphenyl siloxane units.  
     
     
         23 . The base of  claim 22  having an optical refractive index of at least 1.459.  
     
     
         24 . An optically clear, reinforced polysiloxane base consisting essentially of: 
 a copolymer having 12 to 18 mol percent of aryl substituted siloxane units of the formula R 4 ,R 5 —Si—O wherein R 4  and R 5  are identical with one another or are different iron one another and represent phenyl, or mono- or di- lower alkyl substituted phenyl groups, and end blockers containing siloxane units of the formula R 1 ,R 2 ,R 3 —Si—O wherein R 1  and R 2  are alkyl, aryl or substituted alkyl or substituted aryl group, R 1  and R 2  being either identical or different from one another and wherein R 3  is an alkenyl group, the balance of the polymer consisting of dialkyl siloxane units of the formula R 6 ,R 7 —Si—O wherein R 6  and R 7  are identical with one another or are different from one another and are methyl or ethyl groups, the polymer having a degree of polymerization approximately between 100 to 2000;    a trimethyl silyl treated silica reinforcer finely dispersed in the copolymer, the weight ratio of the reinforcer to the copolymer being approximately 15 to 45 parts for 100 parts of the copolymer, the base having an optical refractive index of at least 1.44 and a viscosity of approximately 35,000 to 80,000 cp and is capable of being cured by cross-linking such that the physical properties of the cured cross-linked base include:    an optical refractive index which is at least 1.44;    a Type A durometer hardness value of at least 35;    a tensile strength of at least 500 psi, and    a tear strength of at least 20 pli.    
     
     
         25 . The base of  claim 24  wherein the R 4  and R 5  groups are both phenyl.  
     
     
         26 . The base of  claim 24  wherein the R 1  and R 2  units are both methyl and R 3  is vinyl.  
     
     
         27 . The base of  claim 24  wherein the R 6  and R 7  units are both methyl.  
     
     
         28 . The base of  claim 24  wherein the R 4  and R 5  groups are both phenyl, R 1 , R 2 , R 6  and R 7  are methyl and R 3  is vinyl, and wherein the copolymer contains approximately 15 mol percent diphenyl siloxane units.  
     
     
         29 . The base of  claim 28  wherein the weight ratio of the reinforcer to the base is approximately 27 parts of the reinforcer to 100 parts of the copolymer, and wherein the degree of polymerization of the copolymer is approximately 250 .  
     
     
         30 . The base of  claim 29  having an optical refractive index of at least 1.459.  
     
     
         31 . An intraocular lens body suitable for surgical implantation into the human eye, the lens body being an optically clear reinforced cross-linked silicone elastomer which comprises: 
 a polymer containing 12 to 18 mol percent diphenyl siloxane units, and end blockers containing siloxane units of the formula R 1 ,R 2 ,R 3 —Si—O wherein R 1  and R 2  are alkyl, aryl or substituted alkyl or substituted aryl group, R 1  and R 2  being either identical or different from one another and wherein R 3  is an alkenyl group, the balance of the polymer consisting of dimethyl siloxane units, the polymer having a degree of polymerization approximately between 100 to 2000;    a trimethyl silyl treated silica reinforcer finely dispersed in the polymer, the reinforcer having a weight ratio of approximately 15 to 45 parts to 100 part of the polymer, the lens body having the physical properties of: 
 an optical refractive index which is at least 1.44;  
 a Type A durometer hardness value of at least 35;  
 a tensile strength of at least 500 psi, and  
 a tear strength of at least 20 pli.  
   
     
     
         32 . The intraocular lens of  claim 31  wherein the R 1  and R 2  groups of the end blocking siloxane units of the polymer are methyl, and the R 3  group of the end blocking siloxane unit is vinyl and wherein the polymer contains approximately 14 to 16 mol percent diphenyl siloxane units.  
     
     
         33 . The intraocular lens of  claim 32  wherein the polymer contains approximately 15 mol percent diphenyl siloxane units, has a degree of polymerization of approximately 250, the ratio of polymer to the trimethyl silyl treated silica reinforcer is approximately 27 parts of the reinforcer to 100 parts of the polymer and wherein the optical refractive index of the lens body is at least 1.459.  
     
     
         34 . The intraocular lens of  claim 33  having a type A durometer hardness value of approximately 38 to 40, a tensile strength of approximately 700 to 750 psi, and a tear strength of approximately 40 pli.  
     
     
         35 . An intraocular lens body suitable for surgical implantation into the human eye, the lens body being an optically clear reinforced cross-linked silicone elastomer which comprises: 
 a polymer containing 12 to 18 mol percent of aryl substituted siloxane units of the formula R 4 ,R 5 —Si—O wherein R 4  and R 5  are identical with one another or are different from one another and represent phenyl, or mono- or di- lower alkyl substituted phenyl groups, and end blockers containing siloxane units of the formula R 1 ,R 2 ,R 3 —Si—O wherein R 1  and R 2  are alkyl, aryl or substituted alkyl or substituted aryl group, R 1  and R 2  being either identical or different from one another and wherein R 3  is an alkenyl group, the balance of the polymer consisting of dialkyl siloxane units of the formula R 6 ,R 7 —Si—O wherein R 6  and R 7  are identical with one another or are different from one another and are methyl or ethyl groups, the polymer having a degree of polymerization approximately between 100 to 2000;    a trimethyl silyl treated silica reinforcer finely dispersed in the polymer, the reinforcer having a weight ratio of approximately 15 to 45 parts to 100 part of the polymer, the lens body having the physical properties of: 
 an optical refractive index which is at least 1.44;  
 a Type A durometer hardness value of at least 35;  
 a tensile strength of at least 500 psi, and  
 a tear strength of at least 20 pli.  
   
     
     
         36 . The intraocular lens of  claim 10  wherein the R 4  and R 5  groups are phenyl groups, the R 1  and R 2  groups are methyl, the R 3  group is vinyl, and the R 6  and R 7  groups are methyl.  
     
     
         37 . The intraocular lens of  claim 36  wherein the polymer has a degree of polymerization of approximately 250 .  
     
     
         38 . The intraocular lens of  claim 36  wherein the ratio of the reinforcer to the polymer is approximately 27 parts per weight of the reinforcer for 100 parts per weight of the polymer.  
     
     
         39 . The intraocular lens of  claim 36  further comprising a ultra violet light absorbing agent covalently linked to the cross linked elastomer.  
     
     
         40 . The intraocular lens of  claim 38  having a type A durometer hardness value of approximately 38 to 40, a tensile strength of approximately 700 to 750 psi, and a tear strength of approximately 40 pli.