Patent ID: 6479606
Filing Date: 2002-11-12
Classification: C08F,G02B

Abstract:
Composition comprising polymerizable monomers, characterized in that it comprises:(A) 25 to 60% by weight based on the total weight of polymerizable monomers of at least one dithio(meth)acrylate monomer having formula: in which R4 is selected from the group consisting of linear or branched C2 to C10 alkylene radicals which can comprise, in their chain, one or more â€”Oâ€”, â€”Sâ€” or â€ƒgroups, alkylidene radicals of formula: in which R9 and R10 are C1-C5 alkyl radicals, radicals of formula: in which R11 and R12 are linear or branched C1-C5 alkylene groups which can comprise one or more â€”Oâ€”, â€”Sâ€” or groups in their chains, Xâ€³ is chosen from C1-C5 alkyl radicals and halogens, and n4 is an integer from 0 to 4, and radicals of formula: in which R13 and R14 are linear or branched C1 to C5 alkylene radicals which can comprise, in their chain, one or more â€”Oâ€”, â€”Sâ€” or groups and t and s are equal to 0 or 1, and R5 represents H or â€”CH3. (B) at least one monomer with a high Abbe number comprising 2 to 4 polymerizable groups selected from (meth)acrylic or thio(meth)acrylic groups, and at least one divalent bridged cyclic constituent unit, the bridged cyclic constituent unit or units not being bonded directly to an oxygen atom; (C) at least one polythiol monomer; and, optionally, (D) at least one other monomer which is copolymerizable with the monomers (A), (B) and (C), the composition being devoid of any monomer comprising one or more vinyl functional groups, other than (meth)acrylic and thio(meth)acrylic functional groups, which is different from the monomers (B), whereby the resulting polymer has an Abbe number of at least 40 and a refractive index of at least 1.58.