Bulb

Claim 1

A bulb comprising a glass bulb sealing a light-emitting member therein, and an optical interference film formed on at least one of inner and outer surfaces of said glass bulb and consisting of alternately formed thin titanium oxide layers and thin metal oxide layers of a lower refractive index than that of the thin titanium oxide layers, wherein the thin titanium oxide layers are formed by coating a mixture and thermally decomposing the coated mixture, the mixture consisting of: (A) 5 to 50 parts by weight of an organic compound A obtained by substituting some or all of alkoxyl groups of a titanium alkoxide having a general formula: Ti(OR).sub.4 (wherein R are the same or different alkyl groups having 1 to 18 carbon atoms) with one or more substituting groups selected from the group consisting of a residual group, --OCOR' of a carboxylic acid having a general formula: HOCOR' (wherein R' is an alkyl group having 1 to 18 carbon atoms), and a residual group: --X of an organic compound having a formula HX and capable of forming a chelate ring with titanium; and (B) 95 to 50 parts by weight of an organic titanium compound polymer B obtained by substituting some or all of substituting groups, --OR of a titanium alkoxide polymer obtained by polymerization under water addition of the same or different titanium alkoxides having a general formula: Ti(OR).sub.4 (wherein R are the same or different alkyl groups having 1 to 18 carbon atoms) with one or more substituting groups selected from the group consisting of a residual group, --OCOR' of a carboxylic acid having a general formula: HOCOR' (wherein R' is an alkyl group having 1 to 18 carbon atoms) and a residual group, --X of an organic compound having a formula HX and capable of forming a chelate ring with titanium.