| abstract |
A polymerizable composition is described, which composition comprises a major amount of a polyol(allyl carbonate) monomer, e.g., diethylene glycol bis(allyl carbonate) monomer, and a minor amount of a radically polymerizable second monomer represented by the general formula, n nwherein R 2 is a polyvalent linking group that is free of urethane linkages, e.g., R 2 may be a residue of a polyisocyanate, such as isophorone diisocyanate; R 3 is a residue of a material having a single hydroxy group and at least one allyl group, R 3 being free of urethane linkages, e.g., R 3 may be a residue of a poly(alkylene glycol) allyl ether, such as poly(1,2-propylene glycol) allyl ether; and j is a number from 2 to 4. The second monomer may also be present in the composition in an amount at least sufficient such that a polymerizate, e.g., a plus ophthalmic lens, obtained from the composition is substantially free of tinting defects, e.g., ferns and/or moons. |