Photochromic polyurethane coating and articles having such a coating
AssigneePPG Industries Ohio, Inc.
InventorsRobert J. Bowles, III, Nancyanne Gruchacz, Shanti Swarup, Jeanine A. Conklin, Robert W. Walters, Robin Hunt
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Abstract
Described are photochromic polyurethane coatings that meet commercially acceptable “cosmetic” standards for optical coatings. Also described are articles having such coatings. The coatings exhibit a Fischer microhardness of from 50 to 150 Newtons per mm2 and improved photochromic properties, i.e., the formation of darker activated colors and faster rates of photochromic activation and fade when irradiated with ultraviolet light.
Claims38
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 mm2 as measured with a Fischerscope® H-100 using a 300 milliNewton load, 30 load steps and 0.5 second pauses and exhibiting a ΔOD 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° C. Photochromic Performance Test.
An article comprising, in combination, a substrate of an organic polymeric material and a polyurethane coating containing photochromic compound(s) on at least one surface of said substrate, said photochromic polyurethane coating having a thickness of from 10 to 40 microns, and being prepared from components comprising:
- (a) photochromic compound(s);
- (b) organic polyol(s) comprising
- (i) hard segment-producing organic polyol(s) and
- (ii) soft segment-producing organic polyol(s);
- (c) an isocyanate;
- and
- (d) optionally catalyst;
- the equivalent ratio of the —NCO groups in the isocyanate component to the —OH groups in the organic polyol component(s) ranging from 0.9:1.0 and 2.0:1.0, said components being used in such proportions to produce a photochromic polyurethane coating having a Fisher microhardness of from 50 to 150 Newtons per mm2 as measured with a Fischerscope® H-100 using a 300 milliNewton load, 30 load steps and 0.5 second pauses and exhibiting a 72° F. ΔOD 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° F. Photochromic Performance Test.
Dependencies are inferred from the claim text.