Strong, lightweight photosensitive laminate
AssigneeCorning Glass Works
InventorsJoseph Ference, John E. Megles, Jr.
Life of this patent
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Abstract
Photosensitive laminated glass useful for providing strong, lightweight glass articles incorporating integral surface decorations resistant to mechanical and chemical deterioration in use are described.
Claims8
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.degree.-300.degree. C.) of at least about 75 .times. 10.sup.-7 /.degree. C.;
- (d) the surface layer glass has an average linear coefficient of thermal expansion (0.degree.-300.degree. C.) which is at least 10 .times. 10.sup.-7 /.degree. 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.sub.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.
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.degree.-300.degree. C.) of at least about 75 .times. 10.sup.-7 /.degree. C. and a composition which is essentially free of Li.sub.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.degree.-300.degree. C.) which is at least about 10 .times. 10.sup.-7 /.degree. 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.
Dependencies are inferred from the claim text.