Method of preparing an optical polymerizate

A non elastomeric polymerizate prepared by polymerizing a two-component composition comprised of:

• (a) a first component containing at least one reactant having at least two functional groups selected from isocyanate, isothiocyanate or combinations thereof, the reactant being the reaction product of,
• (i) a polythiol monomer having at least two thiol groups;
• and
• (ii) a monomer having at least two functional groups selected from isocyanate, isothiocyanate or combinations thereof;
• and
• (b) a second component containing at least one polyamine reactant having at least two functional groups selected from primary amine, secondary amine or combinations thereof;
• wherein the molar equivalent ratio of (NCO+NCS) groups from said first component to (—NH2+—NH—) groups from said second component is from 0.5 to 100, wherein the first component and the second component are selected such that the polymerizate has a refractive index of at least about 1.57, an Abbe number of at least about 30, and an initial Barcol hardness of at least 1.

A photochromic article derived from a polymerizate prepared by polymerizing a two-component composition comprised of:

• (a) a first component containing at least one reactant having at least two functional groups selected from isocyanate, isothiocyanate or combinations thereof, the reactant being the reaction product of,
• (i) a polythiol monomer having at least two thiol groups;
• and
• (ii) a monomer having at least two functional groups selected from isocyanate, isothiocyanate or combinations thereof;
• and
• (b) a second component containing at least one polyamine reactant having at least two functional groups selected from primary amine, secondary amine or combinations thereof;
• wherein the molar equivalent ratio of (NCO+NCS) groups from said first component to (—NH2+—NH—) groups from said second component is from 0.5 to 100.