| abstract |
Unsaturated polyester resin-based compositions that are modified for unexpected improvement in uniform, low optical distortion and/or improved tint speed by the addition of one or more additives selected from an allylic ester and/or an acrylic monomer, together with an exotherm depressant, making the modified polyester resin-based composition commercially viable for casting ophthalmic lenses. The additive(s) and exotherm depressant are useful to modify the polyester for sufficient enhancement of optical distortion and/or tint speed such that any unsaturated polyester resin, capable of producing a clear, low color casting, will be improved sufficiently to provide a composition having the required properties for an ophthalmic lens. |