GB2280432A - Glass compositions - Google Patents
Glass compositions Download PDFInfo
- Publication number
- GB2280432A GB2280432A GB9413015A GB9413015A GB2280432A GB 2280432 A GB2280432 A GB 2280432A GB 9413015 A GB9413015 A GB 9413015A GB 9413015 A GB9413015 A GB 9413015A GB 2280432 A GB2280432 A GB 2280432A
- Authority
- GB
- United Kingdom
- Prior art keywords
- glass
- glass composition
- weight
- composition according
- crystal
- 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
Links
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
- C03C3/078—Glass compositions containing silica with 40% to 90% silica, by weight containing an oxide of a divalent metal, e.g. an oxide of zinc
-
- 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
- C03C4/00—Compositions for glass with special properties
- C03C4/0028—Compositions for glass with special properties for crystal glass, e.g. lead-free crystal glass
Abstract
An alkali-silicate glass composition with refractive index of 1.55 or greater, and Abbe number less than 52, suitable for the manufacture of crystal glass, comprises by weight SiO2 50-65%, M2O 12-23%, Bi2O3 1-20%, TiO2 1-15% and SrO 1-20% by weight (where M=Na, K or Li).
Description
GLASS COMPOSITIONS
This invention relates to glass compositions and to articles manufactured from such glass compositions.
The invention relates particularly, but not exclusively, to crystal glassware. Whilst lead crystal glass has been in extensive use for many years for articles such as decanters, drinking glasses and other articles for holding beverages for human consumption and, in the case of decanters, as packaging for longer term storage, the potential toxicity of lead and compounds of lead has resulted in attempts to eliminate the lead content. At the same time, the optical properties which confer the aesthetic qualities of traditional lead glass compositions, and the properties and economics needed for the manufacture of the glass and its products, must be retained. For the traditional lead crystal glass industry, it is also required that the glass should be capable of being worked, that is formed into articles, by hand as well as by machine.
Lead compounds have been used as additives for over three hundred years because of their ability to impart the necessary thermal, optical, mechanical and chemical properties to glasses with economically attainable melting temperatures. Lead compounds also impart a gradual increase in viscosity, as the temperature is reduced to permit the hand working of the glass into the end products, that is, in glass-making terminology, a longer working range. The glasses must also be capable of being cut, ground and polished.
It is known that certain elements and compounds will confer some of the desired properties to an alkali silicate glass. Optical glasses in the region of lanthanum crown have high refractive indices, but low dispersion. Barium compounds are being used by some manufacturers as an altemative to lead in crystal glass manufacture, but the refractive indices and dispersions are much inferior to lead crystal glass. Barium and barium compounds, with the exception of sulphate, are also toxic. Zinc compounds have been used in the manufacture of zinc crystal glasses, but they do not increase refractive index or dispersion significantly above that of the base glass. Titania increases the refractive index and dispersion of all glasses, but is difficult to incorporate without introducing crystallisation and colour, and the glasses are not amenable to hand forming.
It is an object of the present invention to provide a glass composition overcoming these disadvantages, using non-toxic additives, in order to make possible the production of glasses and glass products with favourable production costs, and similar or better aesthetic appearance as lead crystal products, and in particular crystal glasses, based on conventional alkali silicate glass compositions, with high refractive indices in excess of 1.55, high dispersion as measured by an Abbe number of less than 52 and which possess the following properties: - freedom from colour, melting temperatures which permit the use of conventional
crystal glass fumaces, electrical properties which permit electric melting, a working
range to permit hand and machine working, high durability, resistance to solarisation
and extremely low tendency to crystallisation.
According to the present invention, there is provided a glass comprising:
SiO2 50-65% by weight
M2O 12-23% by weight
Bi203 1-20% by weight
TiO2 1-15% by weight
SrO 1-20% by weight where M=Na, K or Li.
Minor additives up to 15% by weight in total may be included in the composition, to obtain specific characteristics for the melting and forming process, and for the appearance of the glass and its product.
If desired, the crystal glass can additionally contain, as refining agents, one or more of antimony trioxide, arsenic trioxide, or cerium oxide, in a total amount up to 1% by weight.
Furthermore, decolourising compounds such as one or more of NiO, Nd203, CoO, Er203 or MnO, may be included in the composition.
We have found that by the addition of bismuth and titanium compounds to an alkali-silicate glass, the refractive index and the dispersion can be increased more than can be achieved by similar additions of lead on both a weight % and mol % basis. We have found also that the addition of bismuth and strontium confers a long working range, compatible with hand working. Moreover, the glasses melt in a temperature range similar to, or slightly lower than, the lead-containing glasses with similar amounts of additives.
Bismuth compounds are, however, more expensive than lead compounds, and therefore the raw materials costs of the bismuth glasses are higher than those of lead glasses. We have found, therefore, that it is possible to replace some or all of the bismuth by titanium, with a consequent improvement in both the refractive indices and dispersions, and a reduction in raw materials costs. Titanium is added most conveniently using titania, but other compounds may be used. The working range of the titanium-containing glasses is shorter than that of the bismuth glass, but is still suitable for hand working in the lower titanium range and for machine forming in the higher titanium range. The addition of strontium to the glasses containing bismuth and titanium increases the working range to permit hand working in the higher titanium range.
The minor additives may be used to modify, for example, electrical properties for the glass to be made in electrically heated fumaces, faint colour which may be preferred in a product, and sonority. The minor additives may include one or more of As203, Sb2O3,
MnO, NiO, Nd203, CaO, CoO, Ear203, ZrO2, B203, La203 and ZnO, to provide specific characteristics that may be required for a particular glass, in accordance with the invented composition.
The tables on page 4 illustrate the compositions, refractive indices and Abbe numbers of glass compositions in accordance with the present invention.
It is found that the glass compositions, according to the invention, are amenable to melting in conventional fumaces in the industry, have a working range to permit the forming of crystal glass products by existing processes, are resistant to solarisation, to attack by the environment, and resistant to the leaching of components of the glass into the contents of containers made from them.
Oxides, hydroxides, carbonates and other oxide-forming compounds, may be used as the raw materials to prepare the glass compositions according to the invention.
The invention also includes articles, particularly crystal glassware, manufactured from the inventive glass compositions.
Table 1 - ComPositions to illustrate the invention
Glass SiO K2O Na 0 Bi | TiO l SrO SrO ZnO CaO Others 1 60.0 20.0 7.5 10.0 2.3 0.2 2 60.0 20.0 5.0 10.0 4.8 0.2 3 57.8 18.0 6.0 7.0 11.0 0.2 4 57.8 16.0 3.0 7.0 16.0 0.2 5 55.4 13.1 17.0 11.0 3.0 0.5 6 55.4 11.9 3.2 12.5 8.5 8.0 0.5 7 52.4 18.1 12.5 9.5 7.0 0.5 8 62.2 11.1 6.2 2.8 17.5 0.2 9 60.2 13.1 1.2 2.4 18.1 4.8 0.2 10 59.9 12.9 2.6 7.8 12.9 3.5 0.4 Table 2 - Refractive indices and Abbe numbers of the illustrative glass
Glass Refractive index Abbe number Density icc 1 1.570 41.6 2.70 2 1.568 42.6 2.68 3 1.569 44.8 2.77 4 1.569 46.5 2.78 5 1.607 37A 2.93 6 1.591 40.6 2.89 7 1.596 39.7 2.89 8 1.559 49.6 2.83 9 1.554 51.9 2.82 10 1.575 45.2 2.77
Claims (7)
- Claims 1. An alkali-silicate glass composition with refractive index of 1.55 or greater, and Abbe number less than 52, suitable for the manufacture of crystal glass comprising by weight SiO2 50-65%, M2O 12-23%, Bi203 1-20%, TiO2 1-15% and SrO 1-20% (where M=Na, K or Li).
- 2. A glass composition according to Claim 1 comprising by weight SiO2 50-65%, M2O 12-23%, Bi2O3 1-20%, TiO2 1-15% and SrO 1-20% (where M=Na, K or Li).
- 3. A glass composition according to any preceding Claim additionally containing one or more of Al2O3, ZnO, B203, CaO, ZrO2 and La203, in total amount up to 15% by weight.
- 4. A glass composition according to any preceding Claim additionally containing as refining agents one or more of antimony trioxide, arsenic trioxide or cerium oxide, in total amount up to 1% by weight.
- 5. A glass composition according to any preceding Claim, additionally containing as decolourising compounds one or more of NiO2, Nd2O3, CoO, Er203, or MnO up to 0.1% by weight.
- 6. A glass composition according to any preceding Claim, further comprising, as minor additives, one or more of As203, Sub203, MnO, NiO, Nd203, Er203 and CoO.
- 7. Articles, particularly crystal glassware, manufactured from glass composition as defined in the preceding Claims.
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB939315717A GB9315717D0 (en) | 1993-07-29 | 1993-07-29 | Glass composition |
Publications (3)
Publication Number | Publication Date |
---|---|
GB9413015D0 GB9413015D0 (en) | 1994-08-17 |
GB2280432A true GB2280432A (en) | 1995-02-01 |
GB2280432B GB2280432B (en) | 1997-04-02 |
Family
ID=10739640
Family Applications (2)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB939315717A Pending GB9315717D0 (en) | 1993-07-29 | 1993-07-29 | Glass composition |
GB9413015A Expired - Fee Related GB2280432B (en) | 1993-07-29 | 1994-06-29 | Glass compositions |
Family Applications Before (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB939315717A Pending GB9315717D0 (en) | 1993-07-29 | 1993-07-29 | Glass composition |
Country Status (2)
Country | Link |
---|---|
GB (2) | GB9315717D0 (en) |
IE (1) | IE80639B1 (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE10258923A1 (en) * | 2002-12-17 | 2004-07-08 | F.X. Nachtmann Bleikristallwerke Gmbh | Lead and barium free crystal glass |
CN110698058A (en) * | 2019-11-01 | 2020-01-17 | 四川虹禾晶科技有限公司 | Crystal glass and preparation method thereof |
Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0560555A2 (en) * | 1992-03-11 | 1993-09-15 | The British Glass Manufacturers Confederation | Glass compositions |
-
1993
- 1993-07-29 GB GB939315717A patent/GB9315717D0/en active Pending
-
1994
- 1994-06-29 GB GB9413015A patent/GB2280432B/en not_active Expired - Fee Related
- 1994-07-28 IE IE940604A patent/IE80639B1/en not_active IP Right Cessation
Patent Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0560555A2 (en) * | 1992-03-11 | 1993-09-15 | The British Glass Manufacturers Confederation | Glass compositions |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE10258923A1 (en) * | 2002-12-17 | 2004-07-08 | F.X. Nachtmann Bleikristallwerke Gmbh | Lead and barium free crystal glass |
DE10258923B4 (en) * | 2002-12-17 | 2007-04-26 | F.X. Nachtmann Bleikristallwerke Gmbh | Lead- and barium-free crystal glass |
CN110698058A (en) * | 2019-11-01 | 2020-01-17 | 四川虹禾晶科技有限公司 | Crystal glass and preparation method thereof |
Also Published As
Publication number | Publication date |
---|---|
GB2280432B (en) | 1997-04-02 |
IE80639B1 (en) | 1998-10-21 |
GB9413015D0 (en) | 1994-08-17 |
GB9315717D0 (en) | 1993-09-15 |
IE940604A1 (en) | 1995-02-08 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 20000629 |