Strong, lightweight photosensitive laminate

Claim 1

An integrally colored laminated glass article consisting of a tensilely stressed core layer composed of a spontaneous opal core glass of alkali aluminosilicate composition and a compressively stressed surface layer fused to and substantially enveloping said core layer composed of a surface layer glass having at least one integrally colored region containing microcrystals of alkali metal fluoride and a coloring metallic silver phase, wherein: (a) the ratio of the thickness of said core layer to the thickness of said surface layer is at least about 8:1; (b) the thickness of said surface layer is at least about 0.002 inches; (c) the core glass has an average linear coefficient of thermal expansion (0°-300° C.) of at least about 75 × 10 -7 /° C.; (d) the surface layer glass has an average linear coefficient of thermal expansion (0°-300° C.) which is at least 10 × 10 -7 /° C. less than that of the core glass; (e) the surface layer glass contains at least about 0.01% silver by weight; (f) the core glass is essentially free of Li 2 O; and (g) the integrally colored region of the surface layer glass contains microcrystals of alkali metal fluoride in a concentration of at least 0.005% by volume and further contains: (i) discrete colloidal particles of metallic silver less than about 200A in the smallest dimension and/or (ii) metallic silver contained within at least a part of said alkali metal fluoride microcrystals, said silver-containing part of the microcrystals being less than about 200A in the smallest dimension and/or (iii) a coating of metallic silver on at least a portion of the surface of the alkali metal fluoride microcrystals, the portion of the microcrystals coated with silver being less than about 200A in the smallest dimension.

Claim 6

A method for producing an integrally colored laminated glass article consisting of a tensilely stressed core layer composed of a spontaneous opal core glass of alkali aluminosilicate composition and a compressively stressed surface layer fused to and substantially enveloping said core layer composed of a surface layer glass having at least one integrally colored region containing microcrystals of alakli metal fluoride and a coloring metallic silver phase, which method comprises the steps of: (a) providing a first melt of an alkali aluminosilicate core glass having an average linear coefficient of thermal expansion (0°-300° C.) of at least about 75 × 10 -7 /° C. and a composition which is essentially free of Li 2 O, the viscosity of said first melt being in the range of about 400-4000 poises; (b) providing a second melt of a photosensitive surface layer glass having an average linear coefficient of thermal expansion (0°-300° C.) which is at least about 10 × 10 -7 /° C. less than that of the core glass and a composition which includes at least about 0.01% silver by weight, the viscosity of said second melt being in the range of about 700-3000 poises; (c) combining the first and second melts into laminated glass sheet and shaping the sheet to provide a laminated glass article comprising a core layer and a photosensitive surface layer, the ratio of the thickness of the core layer to the thickness of the surface layer being at least about 8:1 and the thickness of the surface layer being at least about 0.002 inches; (d) developing selected regions of the photosensitive surface layer into integrally colored regions, said regions containing microcrystals of alkali metal fluoride in a concentration of at least about 0.005% by volume and further containing: (i) discrete colloidal particles of metallic silver less than about 200A in the smallest dimension and/or (ii) metallic silver contained in at least part of said alkali metal fluoride microcrystals, said silver-containing part of the microcrystals being less than about 200A in the smallest dimension and/or (iii) a coating of metallic silver on at least a portion of the surface of the alkali metal fluoride microcrystals, the portion of the microcrystals coated with silver being less than about 200A in the smallest dimension.

Claim 7

A method for producing an integrally colored laminated glass article consisting of a tensilely stressed core layer composed of a spontaneous opal core glass of alkali aluminosilicate composition and a compressively stressed surface layer fused to and substantially enveloping said core layer composed of a surface layer glass having at least one integrally colored region containing microcrystals of alakli metal fluoride and a coloring metallic silver phase, which method comprises the steps of: (a) providing a first melt of an alkali aluminosilicate core glass having an average linear coefficient of thermal expansion (0°-300° C.) of at least about 75 × 10 -7 /° C. and a composition which is essentially free of Li 2 O, the viscosity of said first melt being in the range of about 400-4000 poises; (b) providing a second melt of a photosensitive surface layer glass having an average linear coefficient of thermal expansion (0°-300° C.) which is at least about 10 × 10 -7 /° C. less than that of the core glass and a composition which includes at least about 0.01% silver by weight, the viscosity of said second melt being in the range of about 700-3000 poises; (c) combining the first and second melts into laminated glass sheet and shaping the sheet to provide a laminated glass article comprising a core layer and a photosensitive surface layer, the ratio of the thickness of the core layer to the thickness of the surface layer being at least about 8:1 and the thickness of the surface layer being at least about 0.002 inches; (d) developing selected regions of the photosensitive surface layer into integrally colored regions, said regions containing microcrystals of alkali metal fluoride in a concentration of at least about 0.005% by volume and further containing: (i) discrete colloidal particles of metallic silver less than about 200A in the smallest dimension and/or (ii) metallic silver contained in at least part of said alkali metal fluoride microcrystals, said silver-containing part of the microcrystals being less than about 200A in the smallest dimension and/or (iii) a coating of metallic silver on at least a portion of the surface of the alkali metal fluoride microcrystals, the portion of the microcrystals coated with silver being less than about 200A in the smallest dimension.