GB2164932A - Glass composition - Google Patents
Glass composition Download PDFInfo
- Publication number
- GB2164932A GB2164932A GB08424249A GB8424249A GB2164932A GB 2164932 A GB2164932 A GB 2164932A GB 08424249 A GB08424249 A GB 08424249A GB 8424249 A GB8424249 A GB 8424249A GB 2164932 A GB2164932 A GB 2164932A
- Authority
- GB
- United Kingdom
- Prior art keywords
- glass
- na2o
- tio2
- li2o
- cao
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
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- 239000011521 glass Substances 0.000 title claims abstract description 52
- 239000000203 mixture Substances 0.000 title claims description 10
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 claims abstract description 40
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 claims abstract description 34
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims abstract description 31
- FUJCRWPEOMXPAD-UHFFFAOYSA-N Li2O Inorganic materials [Li+].[Li+].[O-2] FUJCRWPEOMXPAD-UHFFFAOYSA-N 0.000 claims abstract description 21
- KKCBUQHMOMHUOY-UHFFFAOYSA-N Na2O Inorganic materials [O-2].[Na+].[Na+] KKCBUQHMOMHUOY-UHFFFAOYSA-N 0.000 claims abstract description 21
- XUCJHNOBJLKZNU-UHFFFAOYSA-M dilithium;hydroxide Chemical compound [Li+].[Li+].[OH-] XUCJHNOBJLKZNU-UHFFFAOYSA-M 0.000 claims abstract description 19
- 229910052681 coesite Inorganic materials 0.000 claims abstract description 18
- 229910052906 cristobalite Inorganic materials 0.000 claims abstract description 18
- 229910052682 stishovite Inorganic materials 0.000 claims abstract description 18
- 229910052905 tridymite Inorganic materials 0.000 claims abstract description 18
- GOLCXWYRSKYTSP-UHFFFAOYSA-N Arsenious Acid Chemical compound O1[As]2O[As]1O2 GOLCXWYRSKYTSP-UHFFFAOYSA-N 0.000 claims abstract description 16
- 239000000377 silicon dioxide Substances 0.000 claims abstract description 14
- 235000012239 silicon dioxide Nutrition 0.000 claims abstract description 13
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims abstract description 8
- 229910052593 corundum Inorganic materials 0.000 claims abstract description 8
- MRELNEQAGSRDBK-UHFFFAOYSA-N lanthanum oxide Inorganic materials [O-2].[O-2].[O-2].[La+3].[La+3] MRELNEQAGSRDBK-UHFFFAOYSA-N 0.000 claims abstract description 8
- 229910001845 yogo sapphire Inorganic materials 0.000 claims abstract description 8
- KTUFCUMIWABKDW-UHFFFAOYSA-N oxo(oxolanthaniooxy)lanthanum Chemical compound O=[La]O[La]=O KTUFCUMIWABKDW-UHFFFAOYSA-N 0.000 claims abstract description 7
- ADCOVFLJGNWWNZ-UHFFFAOYSA-N antimony trioxide Inorganic materials O=[Sb]O[Sb]=O ADCOVFLJGNWWNZ-UHFFFAOYSA-N 0.000 claims abstract description 5
- 230000003287 optical effect Effects 0.000 claims abstract description 5
- YEAUATLBSVJFOY-UHFFFAOYSA-N tetraantimony hexaoxide Chemical compound O1[Sb](O2)O[Sb]3O[Sb]1O[Sb]2O3 YEAUATLBSVJFOY-UHFFFAOYSA-N 0.000 claims abstract description 5
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 claims description 3
- 229910017583 La2O Inorganic materials 0.000 claims 1
- 238000004031 devitrification Methods 0.000 description 9
- 230000005540 biological transmission Effects 0.000 description 6
- 239000000126 substance Substances 0.000 description 6
- 239000000470 constituent Substances 0.000 description 5
- 230000007423 decrease Effects 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- ZKATWMILCYLAPD-UHFFFAOYSA-N niobium pentoxide Chemical compound O=[Nb](=O)O[Nb](=O)=O ZKATWMILCYLAPD-UHFFFAOYSA-N 0.000 description 4
- 229910000272 alkali metal oxide Inorganic materials 0.000 description 3
- 230000001747 exhibiting effect Effects 0.000 description 3
- 238000000034 method Methods 0.000 description 3
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 2
- AYJRCSIUFZENHW-UHFFFAOYSA-L barium carbonate Chemical compound [Ba+2].[O-]C([O-])=O AYJRCSIUFZENHW-UHFFFAOYSA-L 0.000 description 2
- 239000002585 base Substances 0.000 description 2
- 238000012937 correction Methods 0.000 description 2
- 239000006185 dispersion Substances 0.000 description 2
- 230000002349 favourable effect Effects 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 2
- FGIUAXJPYTZDNR-UHFFFAOYSA-N potassium nitrate Chemical compound [K+].[O-][N+]([O-])=O FGIUAXJPYTZDNR-UHFFFAOYSA-N 0.000 description 2
- 239000011734 sodium Substances 0.000 description 2
- 229910015444 B(OH)3 Inorganic materials 0.000 description 1
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 1
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 1
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 229910000287 alkaline earth metal oxide Inorganic materials 0.000 description 1
- 230000004075 alteration Effects 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 229910052788 barium Inorganic materials 0.000 description 1
- 239000006121 base glass Substances 0.000 description 1
- 235000010338 boric acid Nutrition 0.000 description 1
- KGBXLFKZBHKPEV-UHFFFAOYSA-N boric acid Chemical compound OB(O)O KGBXLFKZBHKPEV-UHFFFAOYSA-N 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 229910000019 calcium carbonate Inorganic materials 0.000 description 1
- 235000010216 calcium carbonate Nutrition 0.000 description 1
- 238000010924 continuous production Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000002425 crystallisation Methods 0.000 description 1
- 230000008025 crystallization Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000006025 fining agent Substances 0.000 description 1
- CMIHHWBVHJVIGI-UHFFFAOYSA-N gadolinium(III) oxide Inorganic materials [O-2].[O-2].[O-2].[Gd+3].[Gd+3] CMIHHWBVHJVIGI-UHFFFAOYSA-N 0.000 description 1
- 239000000156 glass melt Substances 0.000 description 1
- 238000000265 homogenisation Methods 0.000 description 1
- 238000007654 immersion Methods 0.000 description 1
- 239000004615 ingredient Substances 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 229910052744 lithium Inorganic materials 0.000 description 1
- 229910052808 lithium carbonate Inorganic materials 0.000 description 1
- XGZVUEUWXADBQD-UHFFFAOYSA-L lithium carbonate Chemical compound [Li+].[Li+].[O-]C([O-])=O XGZVUEUWXADBQD-UHFFFAOYSA-L 0.000 description 1
- 239000001095 magnesium carbonate Substances 0.000 description 1
- 229910000021 magnesium carbonate Inorganic materials 0.000 description 1
- 235000014380 magnesium carbonate Nutrition 0.000 description 1
- ZLNQQNXFFQJAID-UHFFFAOYSA-L magnesium carbonate Chemical compound [Mg+2].[O-]C([O-])=O ZLNQQNXFFQJAID-UHFFFAOYSA-L 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 239000005304 optical glass Substances 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
- 229910052700 potassium Inorganic materials 0.000 description 1
- 239000011591 potassium Substances 0.000 description 1
- NOTVAPJNGZMVSD-UHFFFAOYSA-N potassium monoxide Inorganic materials [K]O[K] NOTVAPJNGZMVSD-UHFFFAOYSA-N 0.000 description 1
- 235000010333 potassium nitrate Nutrition 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 230000000135 prohibitive effect Effects 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 229910052712 strontium Inorganic materials 0.000 description 1
- 229910000018 strontium carbonate Inorganic materials 0.000 description 1
- LEDMRZGFZIAGGB-UHFFFAOYSA-L strontium carbonate Chemical compound [Sr+2].[O-]C([O-])=O LEDMRZGFZIAGGB-UHFFFAOYSA-L 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- PBCFLUZVCVVTBY-UHFFFAOYSA-N tantalum pentoxide Inorganic materials O=[Ta](=O)O[Ta](=O)=O PBCFLUZVCVVTBY-UHFFFAOYSA-N 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
- 239000010936 titanium Substances 0.000 description 1
- 238000005303 weighing Methods 0.000 description 1
- 229910052725 zinc Inorganic materials 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C3/00—Glass compositions
- C03C3/04—Glass compositions containing silica
- C03C3/076—Glass compositions containing silica with 40% to 90% silica, by weight
- C03C3/089—Glass compositions containing silica with 40% to 90% silica, by weight containing boron
- C03C3/091—Glass compositions containing silica with 40% to 90% silica, by weight containing boron containing aluminium
- C03C3/093—Glass compositions containing silica with 40% to 90% silica, by weight containing boron containing aluminium containing zinc or zirconium
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C3/00—Glass compositions
- C03C3/04—Glass compositions containing silica
- C03C3/076—Glass compositions containing silica with 40% to 90% silica, by weight
- C03C3/089—Glass compositions containing silica with 40% to 90% silica, by weight containing boron
- C03C3/091—Glass compositions containing silica with 40% to 90% silica, by weight containing boron containing aluminium
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C3/00—Glass compositions
- C03C3/04—Glass compositions containing silica
- C03C3/076—Glass compositions containing silica with 40% to 90% silica, by weight
- C03C3/095—Glass compositions containing silica with 40% to 90% silica, by weight containing rare earths
Abstract
This invention relates to glasses especially suitable for optical and ophthalmic applications which exhibit densities less than about 2.65 g/cm<3>, refractive indices between about 1.595-1.607, and Abbe numbers between about 40-47, and which consist essentially, in weight percent on the oxide basis, of SiO2 45-55 B2O3 5-13 Al2O3 0-5 Li2O 1-7.5 Na2O 1-9 K2O 10-24 MgO and/or BaO and/or SrO and/or La2O3 0-6 CaO 0-12 ZnO 0-8 ZrO2 0-7 TiO2 9.5-17.5 As2O3 and/or Sb2O3 0-1 and 13.5 <TiO2+ZrO+La2O3+MgO+CaO+BaO+ZnO+SrO <23.5
Description
SPECIFICATION
Glasses of low density and high index of refraction for ophthalmic and optical applications
The present invention concerns glasses of low density for optical and ophthalmic use.
The utilization of glasses with high indices of refraction in comparison to conventional glasses (n,1= 1.523) permits, at the same power, a reduction of the thickness of the edge (negative power) or of the center of the lens (positive power). However, an increase in the index of refraction leads in a general way to a decrease in the Abbe number (that is to say, an increase in the dispersion of the glass). If the dispersion is too high, the chromatic aberration then becomes significant and causes the appearance of colored fringes at the edges of the lens. To palliate this defect, the glass must have a high Abbe number.
One other not negligible advantage associated with variations in thickness is lighter weight and this throughout the whole range of corrections, with ther exception of very small corrections. For that reason, it is critical that the density of the glass not be too high; one particularly prefers that it be lower than about 2.65 g/cc.
These characteristics will considerably improve the aesthetic appearance of the lens and offer greater comfort to the wearer of the lenses.
Summary of the Invention
The present invention provides the possibility of continuously producing a lightweight glass destined for use in ophthalmic lenses and in optics. In order to assure continuous production with the usual means of forming (pressing), the proposed glasses exhibit a liquidus temperature that is below 1000"C and have a viscosity at this temperature of a few hundred poises.
The base glass system, according to the present invention, is a potassium, titanium borosilicate (K2O-TiO2-B703-SiO2). This system was chosen for its good stability against devitrification when compared with lithium or sodium borosilicates. The principal ingredient destined to raise the index of refraction is Tit,.
With the same object in view, it is also possible to envisage the addition of other oxides to the base system such as: MgO, CoO, BaO, SrO, ZnO, Zoo2, and La,O,. Nevertheless, in order to maintain as low a density as possible, the utilization of these oxides will be undertaken only under certain conditions described below.
The glass will also contain other alkali metal oxides such as Li,O and No70. Outside of their small contribution to the density, their addition to the base system confers greater flexibility in the choice of composition exhibiting good physical and chemical properties.
The inventive glasses are characterized by an index of refraction between about 1.595-1.607, an Abbe number between about 40-47, and a density less than about 2.65 g/cm3. Their transmission in the visible (400 mm) for a thickness of 10 mm is greater than about 83%.
Moreover, they exhibit excellent chemical durability (A.O. test).
According to the present invention, the ranges of oxides composing glasses with the abovementioned properties consist essentially, in weight percent on the oxide basis, of: Si02 45-55 MgO and/or BaO
B203 5-13 and/or SrO and/or La 0 0-6 23 23 Al 203 0-5 CaO 0-12
Li2O 1-7.5 ZnO 0-8
Na2O 1-9 ZrO2 0-7 X20 > 10-24 TiO2 9.5-17.5 As 203 and/or Sb 203 0-1
The ranges of proportions mentioned above for the glass constituents are very important for obtaining the physical and chemical properties required for the application envisaged. More particularly, the SiO2 content will comprise between 45-55% by weight.This range is imposed by the choice of the other components of the glass whose limiting amounts are given in the following paragraphs.
B203 is an essential constituent in the glass composition. Its principal advantages are a small contribution to the density accompanied with a decrease in the viscosity when it is added in substitution for SiO2. The influence of B203 on the viscosity and, consequently, on the facility of melting and forming the glass, also contributes to a glass exhibiting very little coloration.
Therefore, the glass will contain at least 5% by weight. Beyond 13% B2O, and SiO2 content must be reduced in order to maintain the properties, which unfavorably affects the stability of the glass against devitrification.
Al2O3 increases the viscosity of the glass, improves its chemical durability, but, in return, it rapidly deteriorates the resistance of the glass to devitrification. Hence, its amount will not be greater than 5% by weight.
Among the alkali metal oxides, K20 is the one that gives rise to compositions exhibiting a great stability against devitrification. This oxide, when it is added in place of SiO2, not only decreases the density, but also the index of refraction. It can be introduced into the glass up to 24% by weight. Beyond this limit compensation of the refractive index will be effected either with a substantial drop in Abbe number (compensation with TiO2) or with an increase of density (compensation with alkaline earth metal oxides). K20 can be substituted in part by equivalent oxides such as Li2O and Na2O. Nevertheless, as previously pointed out, high quantities of the latter facilitate devitrification of the glass. Hence, the glass will contain more than 10% by weight K2O.
Li2O is the most favorable alkali metal oxide for refractive index. Nevertheless, added in large amounts it reduces the viscosity of the glass and increases its tendency for devitrification.
Therefore, its concentration will not exceed 7.5% by weight.
Na2O is utilized in the same manner as Li2O, but is less favorable for density and refractive index. It can be tolerated with respect to devitrification in greater amounts than Li2O. Its content must be no greater than 9% by weight.
Generally, a combination of three oxides Li2O, Na2O, and K20 will be preferred. In this case there sum will satisfy the following condition: 15% L2O + Na2O + K2O24.5% TiO2 is the constituent which offers the best compromise between density and refractive index. Used in great amount, however, it reduces the visible transmission, facilitates devitrification, increases the density, and rapidly decreases the Abbe number. Therefore, a minimum of 9.5% TiO, is required, but no more than about 17.5% can be tolerated.
In like manner, ZrO, increases the refractive index and density of the glass, but reduces the
Abbe number less rapidly than TiO2. Also, this oxide improves the alkali durability of the glass.
Therefore, the preferred glasses contain at least 1% ZrO2, Its amount will be limited to 7% by weight because, beyond that, crystallization becomes significant.
Among other oxides, MgO, BaO, SrO, and LA203 can be introduced up to 6% by weight, whereas CaO and ZnO can be up to 12% and 8%, respectively. It will be understood these limits comprise maxima when only one of these oxides is added to the glass. These oxides increase the density and refractive index. The maintain the index, their addition must be effected with a reduction in the amount of TiO,. This has the effect of rapidly raising the Abbe number.
However, because of their great contribution to the density, they will be utilized only in a limited manner.
CaO and ZnO will be preferred to MgO for reasons of devitrification and to BaO and SrO for reasons of density. CaO will be the oxide preferably used for glasses of high Abbe number.
In order to have the physical properties (n", V,t, density) in the indicated ranges, the condition specified below must be satisfied.
13.5TiO2+ZrO2+La2O3+RO23.5 (weight %) with R being selected from the group of Mg,
Ca, Ba, Zn, and Sr.
For the same reason, other oxides such as Nb2O5, Gd2O3, Ta2O5, and Y201 can be added in small quantity to the composition. By reason of their prohibitive cost, the glass will preferably not contain them.
Finally, for better fining the glass, one has recourse to the usual fining agents such as As2O3 and Sb2O3. In order to avoid excessive coloration of the glass, their content will be less than 1% by weight.
For glasses having a refractive index between about 1.595 and 1.607, a density less than or equal to about 2.65 g/cm3, and an Abbe number between about 40-47, the glass constituents will preferably be in the ranges specified below:
S102 50-55 CaO 0-8
B203 7.5-12 ZrO2 0-3 Al2O3 0-2 TiO2 9.5-17 Li@O 2-7.5 MgO, BaO, SrO, ZnO, La203 0 Na2O 1-4 TiO2 + ZrO2 + CaO 15-22 K 20 > 10-16 As2O3 0-0.6
Li2O +
Na2O + 17-23
K2O
Prior Art
U.S. Patent No. 2,901,365 disclosed glasses having densities less than 2.7g/cm3, preferably 2.55-2.65g/cm3, and refractive indices between 1.56-1.58.The glasses consisted essentially, in weight percent, of
SiO2 58-64 Ca0+MgO 7.5-14
Na2O 0-17.5 TiO2 5-9
K2O 0-15.5 B203 0-10
Li2O 0-5 Al2O3 0-3
Na2O+K2O+Li2O 12.5-17.5
Although not specified in detail, the Abbe numbers of the working examples ranged from 48.4-53.2.
The SiO and TiO2 contents are outside the ranges of the present inventive glasses, and Li2O and Na2O are optional rather than required components.
Great Britain Patent Application 2,115,403 A discloses ophthalmic and optical glasses demonstrating refractive indices > 1.56, Abbe numbers > 40, and densities < 2.7 g/cm3 consisting essentially, in weight percent of:
Si02 47-75 CaO 0-20 B20 3 1-20 MgO 0-15
Al2O3 0-10 SrO 0-4
2 5 0-5 BaO 0-4 SiO2+B2O3+Al2O3+P 205 57-85 ZnO 0-5 Li2 0 0-15 Ti02 1-15
Na2O 0-10 ZrO2 0-8
K2O 0-10 Nb2O5 0-5 Li2O+Na2O+K2 0 5-17 F 0-5
The K @ @@ntent is @@tside the ra@@@ of the present inventive @lasses and @i@ and Na@O are optional rather than required components.
Description of Preferred Embodiments
The invention is illustrated through the non-limited examples in the table below. The preferred examples are Nos. 3 and 7.
Example of a Glass Melt
The various constituents of the glass are provided by the batch materials specified below:
Oxides Batch Materials SiC sio2
2 B203 B(OH)3 Al?C3 Al (OH) 3 Li2O Li2CO3 Na2 N CO Na2CC3,, N NO K20 K2C03, KNO3
MgO MgCO3
CaO CaCO3
BaO BaCO3
SrO SrCO3
ZnO ZnO
La2O3 La2O3
ZrO2 ZrO2
TiO2 TiO2 As 203 As 203 Sb2O3 Sb2O3
The batch materials chosen preferably contain a minimum amount of Fe@O3 in order to obtain a
glass as "white" as possible.
After weighing, the various batch materials are mixed according to current techniques. The
batch is then charged into a platinum crucible at a temperature of about 1100 When it is
completely melted, the temperature of the batch is brought to about 1300-1400'C and main
tained for about 2-5 hours for homogenization and fining. The bath of glass is thereafter cooled
to a temperature corresponding to the viscosity adequate for forming and cooling in steel molds.
Measurements of Physical and Chemical Properties of Glasses
Measurements of refractive index and Abbe number are effected according to usual methods
(for n, the yellow line of He is utilized) on annealed samples. Density is measured by the
immersion method and expressed in g/cm3.
Chemical resistance is evaluated by the A.O. test described in the journal Applied Optics, 7,
No. 5, page 847, May, 1968. It consists in determining the loss in weight of a polished sample
immersed at 25 C for 10 minutes in a 10% by weight HCI aqueous solution. The loss in weight
is expressed in mg/cm2.
The liquids temperature is determined with the aid of a furnace with a thermal gradient. The
temperature is of 17 hours' duration with the presence of crystals being detected through
observation with an optical microscope.
A rotation viscosimeter was utilized for the determination of high temperature viscosity (in
poises).
The transmission of the glass at 400 mm is determined on polished samples of 10 mm
thickness with the aid of a CARY-14 spectrophotometer.
TABLE
1 2 3
SiO2 51.4 53.1 54.4
B2O3 11.9 7.9 7.9 Al 203 0.5 - 0.5
Li20 2.2 2.5 4.2
Na2O 2.5 8.0 2.5
K2O 14.4 11.7 13.7
CaO 2.2 2.5 ZrC2 - - 1.0
TiO2 14.6 14.0 15.5
As 203 0.3 0.3 0.3 nd (600C/hr.) 1.6004 1.5993 1.6040
Vd (600C/hr.) 41.5 42.4 41.0
Density 2.60 2.63 2.61
A.O. (mg/cm2) - - 0.013
Transmission - - 86.3
Liquidus ( C) #915 < 875 ~895
Liquidus
Viscosity - - 1350 TABLE
(Continued)
4 5 6 SiO2 53.33 54.4 54.1 B 203 8.24 7.7 7.9
Al2O3 ~ - 0.5
Li2O 5.1 5.2 4.2
Na2O 1.96 2.0 2.5 X2O 12.55 11.0 15.2
MgO - 6.0
ZrO2 6.86 -
TiO2 11.96 13.7 15.3 As 203 3 - 0.3 nd (60 C/hr.) 1.6055 1.5989 1.5963
Vd (60 C/hr.) 42.8 42.8 42.1
Density 2.64 2.59 2.60
A.O. (mg/cm2) - - 0.013
Transmission - - 85.8
Liquidus ( C) #955 #945 #890 Liquidus
Viscosity - - s1100 TABLE
(Continued)
7 8 9 10
SiO2 54.4 46 54.6 50.4 B203 7.9 5.4 8.9 8.4
A1203 0.5 4.0 -
Li2O 6.5 1.0 4.7 6.2
Na2O 1.5 2.0 1.0 1.5
K2O 10.3 21.2 11.5 12.0
CaO 6.0 3.9 6.0 12.0
ZrO2 1.0 - 1.0
TiO2 11.9 16.5 12.0 9.5
As2O3 - - 0.3 nd (60OC/hr.) 1.6030 1.6003 1.5998 1.5996
Vd (60 C/hr.) 44.4 41.0 44.4 47.0
Density 2.62 2.63 2.62 2.64
A.O. (mg/cm2) 0.010 0.012 0.009 0.011
Transmission 87.3 87.1 87.2 87.0
Liquidus ( C) #945 #980 #980 #980 Liquidus
Viscosity s390 - - -
Claims (7)
1. A glass for ophthalmic and optical use with a density less than about 2.65 g/cm3, a refractive index between about 1.595-1.607, and an Abbe number between about 40-47, consisting essentially of following composition in weight percent on the oxide basis:
Si02 45-55 La2 3 0-6
B203 5-13 MgO+BaO+SrO+La2O 0-6 Al 203 0-5 CaO 0-12 Li2 0 1-7.5 ZnO 0-8
Na2o 1-9 ZrO2 0-7
K2O > 10-24 As2O3 0-1 TiO@ 9.5-17.5 Sb2 03 0-1
MgO 0-6 As2O3+Sb2O3 0-1
BaO 0-6
SrO 0-6
13.5 < TiO2+ZrO2+La2O3+MgO+CaO+BaO+ZnO+SrO < 23.5
2. A glass according to claim 1 characterized in that in weight percent 15%#Li2O+Na2O± K2O#24.5%.
3. A glass according to claim 1 characterized in that said composition contains at least 1%
ZrO2.
4. A glass according to claim 1 characterized by the following composition:
SiO2 50-55 CaO 0-8
B2O3 7.5-12 ZrO2 0-3 A12 3 0-2 TiO2 9.5-17
Li2O 2-7.5 MgO and/or BaO and/or
Na2O 1-4 SrO and/or ZnO and/or
K2O > 10-16 La2O3 0
Li2O + TiO2 + ZrO2 + CaO 15-22
Na2O + 17-23 As2O3 0-0.6
K20
5. A glass according to claim 4 of a density about 2.61 g/cm3, a refractive index about
1.6040, and an Abbe number about 41 characterized by the following composition:
SiO2 54.4 K2O 13.7 2 7.9 ZrO2 1.0 2 0.5 TiO2 15.5
Li2O 4.2 As2O3 0.3
Na2O 2.5
6. A glass according to claim 4 of a density about 2.62 g/cm3, a refractive index about 1.6030, and an Abbe number about 44.4 characterized by the following compositions: SiO2 54.4 K2O 10.3
B2O3 7.9 Cao 6.0
Al2O3 0.5 ZrC2 1.0
Li2O 6.5 TiO2 11.9
Na2O 1.5
7. A glass as claimed in claim 1 substantially as herein described with reference to the
Examples.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB08424249A GB2164932B (en) | 1984-09-26 | 1984-09-26 | Glass composition |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB08424249A GB2164932B (en) | 1984-09-26 | 1984-09-26 | Glass composition |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB8424249D0 GB8424249D0 (en) | 1984-10-31 |
| GB2164932A true GB2164932A (en) | 1986-04-03 |
| GB2164932B GB2164932B (en) | 1988-05-18 |
Family
ID=10567255
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08424249A Expired GB2164932B (en) | 1984-09-26 | 1984-09-26 | Glass composition |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2164932B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2356861A (en) * | 1999-12-04 | 2001-06-06 | Zeiss Stiftung | Lead-free optical light flint glass |
-
1984
- 1984-09-26 GB GB08424249A patent/GB2164932B/en not_active Expired
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2356861A (en) * | 1999-12-04 | 2001-06-06 | Zeiss Stiftung | Lead-free optical light flint glass |
| FR2801881A1 (en) * | 1999-12-04 | 2001-06-08 | Schott Glas | LIGHT FLINTS LEAD FREE |
| US6551952B2 (en) | 1999-12-04 | 2003-04-22 | Schott Glas | Lead-free optical light flint glass materials |
| GB2356861B (en) * | 1999-12-04 | 2003-10-15 | Zeiss Stiftung | Lead-free optical light flint glass materials |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2164932B (en) | 1988-05-18 |
| GB8424249D0 (en) | 1984-10-31 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 20030926 |