Contact lens material

Abstract

Cross-linked copolymers which are obtained by polymerising a neutral diluent monomer or monomers, a monomer or monomers bearing a center of permanent positive charge, and a bifunctional and/or trifunctional cross-linking agent, are suitable for use in contact lenses. Process for producing them by copolymerisation, contact lens material comprising them, contact lenses made of them and processes for producing contact lenses from them.

1 . A crosslinked copolymer which is obtainable by polymerising a neutral diluent monomer or monomers, a zwitterionic monomer or monomers and a bifunctional or trifunctional crosslinking agent.  
     
     
         2 . A copolymer according to  claim 1  in which the diluent monomer is selected from alkyl (alk)acrylates, dialkylamino alkyl (alk)acrylates, alkyl (alk)acrylamides hydroxyalkyl (alk)acrylates, N-vinyl lactams, styrene, substituted styrene derivatives; and mixtures thereof.  
     
     
         3 . A copolymer according to  claim 2  in which the diluent monomer is selected from vinylpyrrolidone, 2-hydroxyethylmethacrylate, methylmethacrylate and mixtures thereof.  
     
     
         4 . A copolymer according to any one of the preceding claims in which the zwitterionic comonomer or comonomers bears a centre of positive charge provided by a quaternary nitrogen atom.  
     
     
         5 . A copolymer according to any one of the preceding claims which is obtainable by copolymerising a zwitterionic monomer of formula (I) 
       Y—B—X  (I) 
       wherein B is a straight or branched alkylene, oxaalkylene or oligo-oxaalkylene chain or if X contains a carbon-carbon chain between B and the zwitterionic group or if Y contains a terminal carbon atom, a valence bond, 
 X is a zwitterionic group and  
 Y is an ethylenically unsaturated polymerisable group selected from  
                     
 wherein:  
 R is hydrogen or a C 1 -C 4  alkyl group;  
 A is —O— or —NR 1 — where R 1  is hydrogen or a C 1 -C 4  alkyl group or R 1  is —B—X where B and X are as defined above; and  
 K is a group —(CH 2 ) p OC(O)—, —(CH 2 ) p C (O)O—, —(CH 2 ) p OC(O)O—, —(CH 2 ) p NR 2 —, —(CH 2 ) p NR 2 C(O)—, —(CH 2 ) p C(O)NR 2 —, (CH 2 ) p NR 2 C(O)O—, —(CH 2 ) p OC(O)NR 2 —, —(CH 2 ) p NR 2 C(O)NR 2 — (in which the groups R 2  are the same or different), —(CH 2 ) p O—, —(CH 2 ) p SO 3 —, or, optionally in a combination with B, a valence bond, and p is from 1 to 12 and R 2  is hydrogen or a C 1 -C 4  alkyl group.  
 
     
     
         6 . A copolymer according to  claim 5  in which B is an alkylene group of formula —(CR 3   2 ) a —, wherein the groups —(CR 3   2 )— are the same or different, and in each group —(CR 3   2 )— the groups R 3  are the same or different and each group R 3  is hydrogen or C 1 -C 4  alkyl, and a is from 1 to 12; 
 an oxaalkylene group such as alkoxyalkyl having 1 to 6 carbon atoms in each alkyl moiety,  
 an oligo-oxaalkylene group of formula —[(CR 4   2 ) b O] c (CR 4   2 ) b — where the groups —(CR 4   2 )— are the same or different and in each group —(CR 4   2 )— the groups R 4  are the same or different and each group R 4  is hydrogen or C 1 -C 4  alkyl, and b is 2 or 3 and c is from 2 to 11,  
 or if X contains a carbon-carbon chain between B and the centre of positive charge, or if Y contains a terminal carbon atom, a valence bond.  
 
     
     
         7 . A copolymer according to  claim 5  or  6  in which X is a group of formula (IVB):  
       
         
           
           
               
               
           
         
       
       where the groups R 6  are the same or different and each is hydrogen or C 1-4  alkyl and d is from 2 to 4; 
 a group of formula (IVC):  
                     
  where the groups R 7  are the same or different and each is hydrogen or C 1-4  alkyl, and e is from 1 to 4;  
 a group of formula (IVD):  
                     
  wherein the groups R 8  are the same or different and each is hydrogen or C 1-4  alkyl, B 1  is a valence bond or straight or branched alkylene, oxaalkylene or oligo-oxalkalkylene group, f is from 1 to 4 and if B is other than a valence bond, Z is 1 and if B is a valence bond Z is 0 if X is directly bonded to an oxygen or nitrogen atom and otherwise Z is 1;  
 a group of formula (IVE):  
                     
  wherein the groups R 9  are the same or different and each is hydrogen or C 1-4  alkyl, B 2  is a valence bond or a straight or branched alkylene, oxaalkylene or oligo-oxaalkylene group, g is from 1 to 4 and if B is other than a valence bond, Z is 1 and if B is a valence bond Z is 0 if X is directly bonded to an oxygen or nitrogen atom and otherwise Z is 1; or  
 a group of formula (IVF):  
                     
  wherein the groups R 10  are the same or different and each is hydrogen or C 1-4  alkyl, B 3  is a valence bond or a straight or branched alkylene, oxaalkylene or oligo-oxaalkylene group, h is from 1 to 4 if B is other than a valence bond, Z is 1 and if B is a valence bond Z is 0 if X is directly bonded to an oxygen or nitrogen atom and otherwise Z is 1.  
 
     
     
         8 . A copolymer according to  claim 7  in which X is a group of formula (IVD), (IVE) or (IVF) and B 1 , B 2  or B 3  respectively contains up to 24 carbon atoms.  
     
     
         9 . A copolymer according to  claim 7  in which X is a group of formula (IVB) or (IVC).  
     
     
         10 . A copolymer according to  claim 9 , in which the group X is a group of formula (IVC).  
     
     
         11 . A copolymer according to  claim 10  wherein the groups R 7  are all methyl.  
     
     
         12 . A copolymer according to  claim 11  which comprises residues of 2(methacryloyloxy)ethyl-2′-(trimethylammonium) ethyl phosphate inner salt.  
     
     
         13 . A contact lens material comprising a copolymer according to any one of  claims 1  to  12 .  
     
     
         14 . A contact lens comprising a copolymer according to any one of  claims 1  to  12  or a contact lens material according to  claim 13 .  
     
     
         15 . A process for producing a copolymer claimed in any one of  claims 1  to  12  which comprises copolymerising a monomer composition comprising a diluent monomer or monomers, a comonomer or comonomers bearing a centre of permanent positive charge, and a monomer or monomers which will crosslink the resultant polymers.  
     
     
         16 . Use of a copolymer according to any one of  claims 1  to  12  or a contact lens material according to  claim 13  in the production of a contact lens.