Press molding optical articles from acid hydrated glasses

Claim 1

A method of making an optical article comprising the steps of: (a) forming a glass comprising, in mole percent on an oxide basis, about 70 to 80% SiO 2 , 8-18% Na 2 O and/or K 2 O, and about 5 to 10% of a member selected from PbO, ZnO, and mixtures thereof; (b) hydrating the glass under acidic conditions to include in the glass a water content from 3% to 12% by weight thereby resulting in an undesirable alkali concentration gradient in the glass from the surface inwardly (c) reacting the hydrated glass of step (b) with an HF-containing solution under conditions sufficient to remove alkali concentration gradients resulting from step (b) in the glass by removing up to 30 weight percent of the glass; (d) dehydrating the glass, if necessary, to reduce the water content to a range of 3 to 7 weight percent; and (e) pressure molding the glass at a temperature ranging from about 250° to 450° C. and at a pressure ranging from about 5,000 to 13,000 psi against a die having a molding surface smoothness such that, over a distance of at least 0.1 inch, the Roughness Height, on an arithmetic average basis, is less than about 3.0 microinches, the molding being under conditions sufficient to impart to the glass the surface smoothness characteristics of the die.

Claim 2

A method of making an optical article comprising the steps of: (a) forming a glass comprising, in mole percent on an oxide basis, about 70 to 80% SiO 2 , 8-18% Na 2 O and/or K 2 O, and about 5 to 10% of a member selected from PbO, ZnO, and mixtures thereof; (b) hydrating the glass under acidic conditions to include in the glass a water content from 3% to 12% by weight thereby resulting in an undesirable alkali concentration gradient in the glass from the surface inwardly (c) reacting the hydrated glass of step (b) with an HF-containing solution under conditions sufficient to remove alkali concentration gradients resulting from step (b) in the glass by removing up to 30 weight percent of the glass; (d) dehydrating the glass, if necessary, to reduce the water content to a range of 3 to 7 weight percent; and (e) pressure molding the glass at a temperature ranging from about 250° to 450° C. and at a pressure ranging from about 5,000 to 13,000 psi against a die having a molding surface smoothness such that, over a distance of at least 0.1 inch, the Roughness Height, on an arithmetic average basis, is less than about 3.0 microinches, the molding being under conditions sufficient to impart to the glass the surface smoothness characteristics of the die.

Claim 14

A method of making an optical lens comprising the steps of: (a) forming a glass comprising, in mole percent on an oxide basis, about 70 to 80% SiO 2 , 8-18% Na 2 O and/or K 2 O, and about 5 to 10% of a member selected from PbO, ZnO,, and mixtures thereof; (b) hydrating the glass under acidic conditions to include in the glass a water content from 3% to 12% by weight thereby resulting in an undesirable alkali concentraton gradient in the glass from the surface inwardly; (c) reacting the hydrated glass of step (b) with an HF-containing solution under conditions sufficient to remove alkali concentration gradients resulting from step (b) in the glass by removing up to 30 wt.% of the glass; (d) dehydrating the glass, if necessary, to reduce the water content to a range of 3 to 7 weight percent; and (e) pressure molding the glass at a temperature ranging from about 250° to 450° C. and at a pressure ranging from about 5,000 to 13,000 psi between die surfaces, each having a molding surface smoothness such that, over a distance of at least 0.1 inch, the Roughness Height, on an arithmetic average basis, is less than about 3.0 microinches, the molding being under conditions sufficient to form a glass lens having surface smoothness characteristics substantially similar to the die surfaces.

Claim 15

A method of making an optical lens comprising the steps of: (a) forming a glass comprising, in mole percent on an oxide basis, about 70 to 80% SiO 2 , 8-18% Na 2 O and/or K 2 O, and about 5 to 10% of a member selected from PbO, ZnO,, and mixtures thereof; (b) hydrating the glass under acidic conditions to include in the glass a water content from 3% to 12% by weight thereby resulting in an undesirable alkali concentraton gradient in the glass from the surface inwardly; (c) reacting the hydrated glass of step (b) with an HF-containing solution under conditions sufficient to remove alkali concentration gradients resulting from step (b) in the glass by removing up to 30 wt.% of the glass; (d) dehydrating the glass, if necessary, to reduce the water content to a range of 3 to 7 weight percent; and (e) pressure molding the glass at a temperature ranging from about 250° to 450° C. and at a pressure ranging from about 5,000 to 13,000 psi between die surfaces, each having a molding surface smoothness such that, over a distance of at least 0.1 inch, the Roughness Height, on an arithmetic average basis, is less than about 3.0 microinches, the molding being under conditions sufficient to form a glass lens having surface smoothness characteristics substantially similar to the die surfaces.