Patent ID: 6187444
Filing Date: 2001-02-13
Classification: B29D,C08G,C09K,G03C,Y10T

Abstract:
An article comprising, in combination, a substrate and a polyurethane coating containing photochromic compound(s) on at least one surface of said substrate, said photochromic polyurethane coating being prepared from components comprising:(a) an organic polyol comprising sections of hard and soft segment-producing polyols;(b) an isocyanate,(c) photochromic compound(s) and(d) optional catalyst,the equivalent ratio of the NCO groups in the isocyanate component to the --OH groups in the organic polyol component ranging from 0.3:1 to 3:1, said components being used in such proportions to produce a photochromic polyurethane coating having a Fischer microhardness of from 50 to 150 Newtons per mm.sup.2 as measured with a Fischerscope.RTM. H-100 using a 300 milliNewton load, 30 load steps and 0.5 second pauses and exhibiting a .DELTA.OD of at least 0.15 after 30 seconds and at least 0.44 after 30 minutes, and a Bleach Rate of less than 200 seconds--all as measured in the 72.degree. C. Photochromic Performance Test.