Patent ID: 6602603
Filing Date: 2003-08-05
Classification: C08F,C09D,G02B,Y10T

Abstract:
An article comprising, in combination, a substrate and a photochromic poly(meth)acrylic coating on at least one surface of said substrate, said coating comprising a polymerizate of:(a) at least two difunctional (meth)acrylate monomers selected from: (i) a first monomer, represented by the following general formula: wherein each R1 is hydrogen or methyl, each R2 is hydrogen or C1-C2 alkyl, m and n are each a positive number, the sum of m and n being greater than 3 but less than 15, and A is a divalent linking group selected from the group consisting of straight or branched chain alkylene, phenylene, C1-C9 alkyl substituted phenylene, and a group represented by the following graphic formula: wherein, each R3 is C1-C4 alkyl, chlorine or bromine, p and q are each an integer from 0 to 4, represents a divalent benzene group or a divalent cyclohexane group and X is O, S, â€”S(O2)â€”, â€”C(O)â€”, â€”CH2â€”, â€”CH&boxH;CHâ€”, â€”C(CH3)2â€”, â€”C(CH3)(C6H5)â€” or is the divalent benzene group, and X is O, S, â€”CH2â€”, or â€”C(CH3)2â€” when is the divalent cyclohexane group; and(ii) a second monomer represented by the following general formula: wherein each R1 is hydrogen or methyl, x, y and z are each a number between 0 and less than 15 and the sum of x, y and z is greater than 3 and less than 15; said monomers being in a weight ratio of (i):(ii) of from greater than 10:90 to less than 90:10;(b) a photochromic amount, of a photochromic component; and (c) from 0 to 10 weight percent, based on the total weight of monomers, of polymerization initiator selected from thermal initiators, photoinitiators or mixtures of such initiators, said coating being free of chain transfer agents and said components (a), (b) and (c) being used in such proportions to produce a photochromic poly(meth)acrylic coating having a Fischer microhardness of between 50 and 150 Newtons per mm2, a &Dgr;OD at 30 seconds of at least 0.15 and at 15 minutes of at least 0.50, and a bleach rate of not more than 200 secondsâ€”all as measured at 22Â° C. (72Â° F.).