Patent ID: 7208229

Claim:
An optical element which comprises an optical substrate and a cured film made of a coating composition formed on the surface of the optical substrate, wherein the coating composition comprises the following components (A) and (B): component (A): at least one silicon-containing substance selected from the group consisting of organic silicon compounds of formula (I): (R 1 ) a (R 3 ) b Si(OR 2 ) 4−(a+b) (I) wherein each of R 1 and R 3 is an alkyl group, an aryl group, a halogenated alkyl group, a halogenated aryl group, an alkenyl group, or an organic group having an epoxy group, an acryloyl group, a methacryloyl group, a mercapto group, an amino group or a cyano group, which is bonded to the silicon atom by a Si-C bond, R 2 is a C 1-8 alkyl group, an alkoxyalkyl group or an acyl group, and each of a and b is an integer of 0, 1 or 2, provided that a+b is an integer of 0, 1 or 2, and the formula (II): [(R 4 ) c Si(OX) 3-c ] 2 Y (II) wherein R 4 is a C 1-5 alkyl group, X is a C 1-4 alkyl group or an acyl group, Y is a methylene group or a C 2-20 alkylene group, and c is an integer of 0 or 1, and their hydrolyzates; and component (B): colloidal particles of a modified metal oxide which have primary particle diameters of from 2 to 100 nm and which contain particles (c) comprising colloidal particles (a) of a metal oxide having primary particle diameters of from 2 to 60 nm, selected from the group consisting of Fe 2 O 3 particles, CuO particles, ZnO particles, Y 2 O 3 particles, ZrO 2 particles, Nb 2 O 5 particles, MoO 3 particles, In 2 O 3 particles, SnO 2 particles, Ta 2 O 5 particles, WO 3 particles, PbO particles, Bi 2 O 3 particles, SnO 2 —WO 3 composite particles, SnO 2 —ZrO 2 composite particles, TiO 2 —ZrO 2 —SnO 2 composite particles, ZnSb 2 O 6 particles, InSbO 4 particles, ZnSnO 3 particles and combinations thereof, as nuclei, and a coating material (b) comprising alkali component-containing diantimony pentoxide colloidal particles having a M/Sb 2 O 5 molar ratio, where M is an alkali metal, ammonium, a quaternary ammonium or an amine, of from 0.02 to 4.00, coated on the surface of the particles (a).