Patent number: 6387512
Abstract: A photochromic grey coloring 2H-naphtho[1,2-b]pyran of formula (1) wherein R1 is selected from mono-, di- or poly-substituted aryl groups, mono-, di- or poly-substituted naphthyl groups and mono-, di- or poly-substituted heteroaryl groups, wherein at least one substituent is a nitrogen containing group, including amino, C1-C20 and C6-C20 alkylamino, C1-C20 and C6-C20 dialkylamino, C2-C20 dialkenylamino, C2-C20 or C4-C20 di(polyalkenyl)amino, arylamino, diarylamino, C1-C20 alkylarylamino, tetra (C1-C10 linear or branched alkyl) guanidino and cyclic-amino groups and at least one of R7 and R9, which may be the same or different, is selected from C1-C20 N alkylamino C1-C20 N-alkylamido, C1-C20 N,N-dialkylamido, amido, nitro, amino, C1-C20 alkylamino, C1-C20 dialkylamino, C2-C20 dialkenylamino, C4-C20 di(polyalkenyl)amino, arylamino, diarylamino, C1-C20 alkylarylamino, or cyclicamino groups.
Type:
Grant
Filed:
March 16, 2001
Date of Patent:
May 14, 2002
Assignee:
James Robinson Limited
Inventors:
David Allan Clarke, Bernard Mark Heron, Christopher David Gabbutt, John David Hepworth, Steven Michael Partington, Stephen Nigel Corns