Photochromic microsheet

Claim 2

Transparent photochromic glass microsheet demonstrating good chemical durability, a liquidus temperature less than the temperature at which the glass displays a viscosity of 10 5 poises, a long term stability against devitrification when in contact with platinum and/or refractory ceramics at temperatures corresponding to glass viscosities in the range of about 10 4 -10 5 poises, and which, in cross sections between about 0.25-0.5 mm, will exhibit the following photochromic properties: (a) at room temperature will darken to a luminous transmittance below 50% in the presence of actinic radiation; (b) at room temperature will fade at least 20 percentage units of transmission after five minutes' removal from the actinic radiation; and (c) at room temperature will fade to a luminous transmittance in excess of 80% in no more than one hour after being removed from the actinic radiation; said glass consisting essentially, in weight percent on the oxide basis as calculated from the batch, of 54-66% SiO 2 , 7-15% Al 2 O 3 , 10-30% B 2 O 3 , 3-15% Na 2 O, 0.4-1.5% PbO, 0.2-0.5% Br, 0.5-1.2% Cl, 0.2-0.5% F, 0.008-02.03% CuO, and >0.03%-1% Ag.

Claim 3

Transparent photochromic glass microsheet according to claim 1 wherein said glass composition also contains up to 1% total of transition metal oxides and/or up to 5% total of rare earth oxides as colorants.

Claim 4

Transparent photochromic glass microsheet according to claim 1 wherein said glass composition also contains up to 4% Li 2 O and up to 10% K 2 O, the sum of Li 2 o+Na 2 o+K 2 O not exceeding 15%, up to 3% P 2 O 5 , up to 1% I, and up to 0.5% CdO.

Claim 5

Transparent photochromic glass microsheet according to claim 1 wherein said glass displays a long term stability against devitrification when in contact with sillimanite, mullite, zircon, and/or high density alumina-containing refractory ceramics.

Claim 6

A transparent glass-plastic composite lens having a body portion of plastic and a surface layer and/or an internal lamina buried in said plastic body portion composed of photochromic glass microsheet demonstrating good chemical durability, a liquidus temperature less than the temperature at which the glass displays a viscosity of 10 5 poises, a long term stability against devitrification when in contact with platinum and/or refractory ceramics at temperatures corresponding to glass viscosities in the range of about 10 4 -10 5 poises, and which, in cross sections between about 0.25-0.5 mm, will exhibit the following photochromic properties: (a) at room temperature will darken to a luminous transmittance below 50% in the presence of actinic radiation; (b) at room temperature will fade at least 20 percentage units of transmission after five minutes' removal from the actinic radiation; and (c) at room temperature will fade to a luminous transmittance in excess of 80% in no more than one hour after being removed from the actinic radiation; said glass consisting essentially, in weight percent on the oxide basis as calculated from the batch, of 54-66% SiO 2 , 7-15% Al 2 O 3 , 10-30% B 2 O 3 , 3-15% Na 2 O, 0.4-1.5% PbO, 0.2-0.5% Br, 0.5-1.2% Cl, 0.2-0.5% F, 0.008-0.03% CuO, and >0.03%-1% Ag.

Claim 7

A transparent glass-plastic composite lens having a body portion of plastic and a surface layer and/or an internal lamina buried in said plastic body portion composed of photochromic glass microsheet demonstrating good chemical durability, a liquidus temperature less than the temperature at which the glass displays a viscosity of 10 5 poises, a long term stability against devitrification when in contact with platinum and/or refractory ceramics at temperatures corresponding to glass viscosities in the range of about 10 4 -10 5 poises, and which, in cross sections between about 0.25-0.5 mm, will exhibit the following photochromic properties: (a) at room temperature will darken to a luminous transmittance below 50% in the presence of actinic radiation; (b) at room temperature will fade at least 20 percentage units of transmission after five minutes' removal from the actinic radiation; and (c) at room temperature will fade to a luminous transmittance in excess of 80% in no more than one hour after being removed from the actinic radiation; said glass consisting essentially, in weight percent on the oxide basis as calculated from the batch, of 54-66% SiO 2 , 7-15% Al 2 O 3 , 10-30% B 2 O 3 , 3-15% Na 2 O, 0.4-1.5% PbO, 0.2-0.5% Br, 0.5-1.2% Cl, 0.2-0.5% F, 0.008-0.03% CuO, and >0.03%-1% Ag.

Claim 8

A transparent glass-plastic composite lens according to claim 5 wherein said glass composition also contains up to 1% total of transition metal oxides and/or up to 5% total of rare earth metal oxides as colorants.

Claim 9

A transparent glass-plastic composite lens according to claim 5 wherein said glass composition also contains up to 4% Li 2 O and up to 10% K 2 O, the sum of Li 2 O+Na 2 O+K 2 O not exceeding 15%, up to 3% P 2 O 5 , up to 1% I, and up to 0.5% CdO.

Claim 10

A transparent glass-plastic composite lens according to claim 5 wherein said glass displays a long term stability against devitrification when in contact with sillimanite, mullite, zircon, and/or high density aluminacontaining refractory ceramics.

Claim 11

A transparent glass-plastic composite lens according to claim 5 wherein said plastic is an allyl diglycol carbonate.

Claim 12

A transparent glass-plastic composite lens according to claim 9 wherein said plastic is made from diethylene glycol bis(allyl carbonate) resin.