Photoflash lamp with polycarbonate coating

Claim 2

A photoflash lamp comprising an hermetically sealed glass envelope, a combustion-supporting gas in said envelope, a quantity of combustible material located in said envelope, ignition means attached to said envelope and disposed in operative relationship to said combustible material, a protective coating substantially comprising an acidified polycarbonate resin on the exterior surface of said glass envelope, and an alkali-barrier coating disposed between said polycarbonate coating and said glass envelope for extending the shelf-life of said polycarbonate coating under humid conditions by preventing alkali released by said glass envelope from reacting with said polycarbonate coating.

Claim 3

A lamp according to claim 1 wherein the composition of said alkali-barrier coating comprises a material selected from the group consisting of polytetrafluoroethylene, epoxy resins, polychlorotrifluoroethylene fluids or resins, fluorinated hydrocarbon fluids or resins, polypropylene, polymethyl-methacrylate, thermosetting acrylic resins, polyvinylidine chloride, silicone resins and fluids, allyl resins, polyallomers, polybutylene, polyesters, polymethylpentene, polysulfone, chlorinated polyvinyl chloride, and the natural waxes such as carnauba wax.

Claim 4

A lamp according to claim 2 wherein said alkali-barrier coating is clear.

Claim 5

A lamp according to claim 1 wherein said alkali-barrier coating is disposed as a thin film between said glass envelope and said acidified polycarbonate coating.

Claim 6

A lamp according to claim 1 wherein the thickness of said alkali-barrier coating is less than about 0.001 inch.

Claim 7

A lamp according to claim 1 wherein the thickness of said acidified polycarbonate coating is greater than about 0.015 inch.

Claim 8

A lamp according to claim 1 wherein the acidified resin of said polycarbonate coating comprises a homogeneous mixture of from about 70 to 99.9 percent by weight of a polycarbonate resin and from about 0.1 to 30 percent by weight of a compatible acidifying agent having a first pKa value in a range from about 1.0 to 6.5.

Claim 9

A lamp according to claim 1 wherein said acidified polycarbonate coating is vacuum-formed on said envelope and exerts a compressive load on the glass envelope of from about 1000 to 3000 pounds per square inch.

Claim 10

A lamp according to claim 1 wherein said polycarbonate coating comprises a preformed sleeve of material substantially comprising an acidified polycarbonate resin which has been vacuum-formed onto said glass envelope.

Claim 11

A lamp according to claim 9 wherein said alkali-barrier coating comprises a resin.

Claim 12

A lamp according to claim 10 wherein said alkali-barrier coating comprises polytetrafluoroethylene.

Claim 13

A lamp according to claim 9 wherein said alkali-barrier coating comprises a thin film.

Claim 14

A lamp according to claim 12 wherein said alkali-barrier coating is a polychlorotrifluoroethylene fluid or an alkylmethyl polysiloxane in which the alkyl group is a saturated moiety containing an average of from 4 to 16 carbon atoms.

Claim 15

A photoflash lamp comprising an heremetically sealed glass envelope, a combustion-supporting gas in said envelope, a quantity of combustible material located in said envelope, ignition means attached to said envelope and disposed in operative relationship to said combustible material, a protective coating substantially comprising a polycarbonate resin on the exterior surface of said glass envelope, and an alkali-barrier coating disposed between said polycarbonate coating and said glass envelope for extending the shelf-life of said polycarbonate coating under humid conditions by preventing alkali released by said glass envelope from reacting with said polycarbonate coating, said alkali-barrier coating comprising a polychlorotrifluoroethylene fluid or an alkylmethyl polysiloxane in which the alkyl group is a saturated moiety containing an average of from 4 to 16 carbon atoms.

Claim 16

A photoflash lamp comprising an heremetically sealed glass envelope, a combustion-supporting gas in said envelope, a quantity of combustible material located in said envelope, ignition means attached to said envelope and disposed in operative relationship to said combustible material, a protective coating substantially comprising a polycarbonate resin on the exterior surface of said glass envelope, and an alkali-barrier coating disposed between said polycarbonate coating and said glass envelope for extending the shelf-life of said polycarbonate coating under humid conditions by preventing alkali released by said glass envelope from reacting with said polycarbonate coating, said alkali-barrier coating comprising a polychlorotrifluoroethylene fluid or an alkylmethyl polysiloxane in which the alkyl group is a saturated moiety containing an average of from 4 to 16 carbon atoms.

Claim 17

A photoflash lamp comprising an hermetically sealed glass envelope, a combustion-supporting gas in said envelope, a quantity of combustible material located in said envelope, ignition means attached to said envelope and disposed in operative relationship to said combustible material, a protective coating substantially comprising a polycarbonate resin on the exterior surface of said glass envelope, and an alkali-barrier coating disposed between said polycarbonate coating and said glass envelope for extending the shelf-life of said polycarbonate coating under humid conditions by preventing alkali released by said glass envelope from reacting with said polycarbonate coating, the composition of said alkali-barrier coating comprising a material selected from the group consisting of polypropylene, polyvinylidine chloride, polybutylene, polymethylpentene, and chlorinated polyvinyl chloride.

Claim 18

A photoflash lamp comprising an hermetically sealed glass envelope, a combustion-supporting gas in said envelope, a quantity of combustible material located in said envelope, ignition means attached to said envelope and disposed in operative relationship to said combustible material, a protective coating substantially comprising a polycarbonate resin on the exterior surface of said glass envelope, and an alkali-barrier coating disposed between said polycarbonate coating and said glass envelope for extending the shelf-life of said polycarbonate coating under humid conditions by preventing alkali released by said glass envelope from reacting with said polycarbonate coating, the composition of said alkali-barrier coating comprising a material selected from the group consisting of polypropylene, polyvinylidine chloride, polybutylene, polymethylpentene, and chlorinated polyvinyl chloride.