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
  • C03C3/083—Glass compositions containing silica with 40% to 90% silica, by weight containing aluminium oxide or an iron compound
  • C03C3/085—Glass compositions containing silica with 40% to 90% silica, by weight containing aluminium oxide or an iron compound containing an oxide of a divalent metal
  • C03C3/087—Glass compositions containing silica with 40% to 90% silica, by weight containing aluminium oxide or an iron compound containing an oxide of a divalent metal containing calcium oxide, e.g. common sheet or container glass
• • 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
  • C03C1/00—Ingredients generally applicable to manufacture of glasses, glazes, or vitreous enamels
  • C03C1/10—Ingredients generally applicable to manufacture of glasses, glazes, or vitreous enamels to produce uniformly-coloured transparent products
• • 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
  • C03C1/00—Ingredients generally applicable to manufacture of glasses, glazes, or vitreous enamels
  • C03C1/10—Ingredients generally applicable to manufacture of glasses, glazes, or vitreous enamels to produce uniformly-coloured transparent products
  • C03C1/105—Ingredients generally applicable to manufacture of glasses, glazes, or vitreous enamels to produce uniformly-coloured transparent products by the addition of colorants to the forehearth of the glass melting furnace
• • 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
  • C03C4/02—Compositions for glass with special properties for coloured glass
• • 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
  • C03C4/08—Compositions for glass with special properties for glass selectively absorbing radiation of specified wave lengths

Definitions

• the invention relates to a glass composition of silica-soda-lime type colored blue. More particularly, the invention relates to a blue glass composition for the preparation of flat glasses by floating on a bath of molten metal, such as tin (float process), these flat glasses being intended in particular, but not exclusively, to form windshields and side windows situated at the front of a vehicle.
• molten metal such as tin (float process)
• Automobile windows are subject to very strict requirements. As regards optical properties, these requirements are governed by regulations, for example with regard to the light transmission of a windshield or else with regard to the comfort of the user, in particular as concerns the energy transmission.
• the windows situated at the front of vehicles also have to meet the wishes of automobile manufacturers as regards the color, in particular relating to the dominant wavelength and to the purity.
• Iron is a coloring agent which fully satisfies these requirements.
• the presence of iron in the form of ferrous ions Fe 2+ distinct from ferric ions Fe 3+ , makes it possible to reduce the transmission of infrared radiation through the glass and therefore to lower the energy transmission.
• iron introduces a green coloring which matches well the color of the majority of automobiles.
• a blue coloring can be obtained simply by adding cobalt oxide to the glass composition.
• This oxide leads to a reduction in the light transmission of the glass, the transmission of infrared radiation through the glass for its part being only very slightly affected.
• Another way of coloring the glass blue consists in using iron as sole coloring agent, provided, however, that the redox factor (content of ferrous ions FeO/total content of ferrous ions and of ferric ions Fe 2 O 3 ) is maintained at a relatively high value, of the order of 50%.
• the redox factor content of ferrous ions FeO/total content of ferrous ions and of ferric ions Fe 2 O 3
• Such a high redox factor presents problems with regard to the implementation of the process as the melting of the glass is rendered more difficult, which increases in proportion the risk of seeing the appearance in the glass of inclusions of incompletely melted material, such as silica.
• the iron is liable to react with the sulfate used for the refining of the glass in the bath to form iron sulfide, which gives the glass a yellow to brown coloring.
• Blue-colored glasses can also be obtained by combining several coloring agents.
• EP-A-0 820 964 a mixture combining iron (0.4 to 1.1%) and cobalt oxide (10 to 75 ppm) is used to form a blue glass having a dominant wavelength varying from 480 to 490 nm and an excitation purity of at least 6%.
• the proportion of iron in the ferrous state is between 20 and 40%.
• the coloring effect related essentially to the presence of cobalt oxide in the glass, is reflected by a very strong blue color.
• EP-A-0 814 064 provision is made to combine iron (0.53 to 1.1%), cobalt oxide (5 to 40 ppm) and optionally chromium oxide (up to 100 ppm) to form blue glasses exhibiting a dominant wavelength varying from 485 to 491 nm and a purity varying from 3 to 18%.
• the redox is between 0.25 and 0.35.
• EP-A-1 023 245 use is made, as above, of iron (0.4 to 1.0%), cobalt oxide (4 to 40 ppm) and optionally chromium oxide (up to 100 ppm) to form a glass exhibiting a dominant wavelength varying from 485 to 489 nm and an excitation purity ranging from 3 to 18%.
• This glass is prepared at a redox of between 0.35 and 0.6, which is not a usual redox value for the float process. It is therefore necessary in this case to use specific heating means to melt the composition, as already specified above. This is consequently reflected by an increase in the cost of the glass produced.
• the processes for producing the blue glasses mentioned above are carried out with a total iron content at least equal to 0.4% and/or under relatively high redox conditions. They generally operate with a given glass composition and it is not recommended to adjust the nature or the content of the components participating in the composition of the vitrifiable mixture. This is because any change in the composition of the glass in the furnace requires a transition time during which the glass produced does not have the expected optical properties and the expected coloring. This transition time increases in proportion as the content of coloring agents increases. Furthermore, limiting the content of iron, in particular of ferrous iron, introduces an additional advantage as the energy requirement for melting the glass composition is less, which contributes to reducing the cost of the glass.
• the present invention intends to provide a glass composition of silica-soda-lime type which makes it possible to form a blue-colored glass which overcomes the abovementioned disadvantages. More specifically, an aim of the present invention is to provide a composition capable of being employed under the conditions of the float process to form a glass exhibiting a blue coloring and having spectral properties compatible with use as automobile window or in the construction industry, said composition comprising a reduced content of coloring agents, in particular of iron.
• the low content of iron in the composition according to the invention makes it possible to be able to prepare the glass in a float plant suited to the production of “clear” glass, in which the content of iron generally does not exceed 0.6%. This type of plant proves to be particularly advantageous economically for the reasons explained above.
• the invention makes it possible to provide a blue glass suitable for forming an automobile window which, for a thickness varying from 3 to 5 mm, exhibits a light transmission LT A at least equal to 60% and a selectivity at least equal to 1.1.
• the blue glass composition of silica-soda-lime type which comprises the coloring agents below in a content varying within the following limits, by weight: Fe 2 O 3 (total iron) 0.2 to 0.51% CoO 10 to 50 ppm Cr 2 O 3 10 to 300 ppm CuO 0 to 400 ppm the glass exhibiting a redox factor of less than or equal to 0.35, a dominant wavelength ⁇ D of between 485 and 489 nm, an excitation purity of less than 13% and a selectivity at least equal to 1.1 under a thickness varying between 3 and 5 mm.
• sica-soda-lime is used here in the broad sense and relates to any glass composition which comprises the following constituents (as % by weight): SiO 2 64-75% Al 2 O 3 0-5% B 2 O 3 0-5% CaO 5-15% MgO 0-5% Na 2 O 10-18% K 2 O 0-5% BaO 0-5%
• the silica-soda-lime glass composition can comprise, in addition to inevitable impurities, a small proportion (up to 1%) of other constituents, for example agents which help in the melting or in the refining of the glass (SO 3 , Cl, Sb 2 O 3 , As 2 O 3 ) or which originate from a possible addition of recycled cullet to the vitrifiable mixture.
• the term “redox” is understood to mean the ratio of the content by weight of the ferrous oxide, expressed in the form of FeO, to the content by weight of total iron, expressed in the form of oxide Fe 2 O 3 .
• the “selectivity” is defined as being the ratio of the light transmission under illuminant A (LT A ) to the total energy transmission (T E ) for a given thickness.
• the composition according to the invention makes it possible to obtain a blue-colored glass of high purity even for a significant level of light transmission.
• the glass formed from the composition according to the invention exhibits a high selectivity, which is particularly advantageous when the latter is intended to form windows for the construction industry or the automobile industry. This is because, with such a glass, heating related to solar radiation is limited and, for this reason, the comfort with regard to the temperature of the occupants of the building or automobile is increased.
• the selectivity of the glass is equal to or greater than 1.3 and even better still is greater than or equal to 1.4.
• composition according to the invention proves to be advantageous in forming glasses which, for a thickness varying from 3 to 5 mm, have a light transmission LT A at least equal to 60%, preferably 70%, and are thus suitable for forming front side windows and windshields of automobiles.
• the glass in accordance with the invention has an excitation purity of less than 9% and advantageously of greater than 4%.
• the dominant wavelength of the glass obtained by virtue of the composition according to the invention is at least equal to 487 nm.
• the glass composition in accordance with the invention comprises contents of chromium oxide and of cobalt oxide which satisfy the relationship: 100 ⁇ Cr 2 O 3 /(CoO) 2 >7.
• cobalt oxide added to a composition comprising iron gives the glass a blue coloring but also results in a decrease in the light transmission. It is therefore essential to control the content of cobalt oxide in order for the light transmission of the glass to remain compatible with the use for which it is intended. In the majority of cases, the content of cobalt oxide varies from 15 to 40 ppm, preferably from 20 to 35 ppm.
• the presence of iron in the glass composition can result from the starting materials, as impurities, or from a deliberate addition. It is known that, if the iron content is increased, the glass takes on a green color and its light transmission is reduced. Conversely, on reducing the proportion of iron, in particular in the form of ferrous ions, the performance in terms of energy transmission deteriorates without affecting the light transmission.
• the total iron content in the composition is greater than 0.30%, better still greater than 0.40% and advantageously greater than 0.45%.
• the chromium oxide confers a green/yellow coloring on the glass and also reduces its light transmission.
• the addition of chromium to a composition comprising cobalt softens the vivid blue coloring and thus moderates the intensity of the coloring, which makes it possible to retain a dominant wavelength which is not very high while having a lower purity than with cobalt alone.
• the content of chromium oxide is preferably greater than or equal to 20 ppm, better still less than or equal to 250 ppm. In a particularly advantageous way, the content of chromium oxide is between 30 to 80 ppm.
• the copper oxide gives a turquoise blue coloring to the glass. It absorbs infrared radiation and, for this reason, contributes to reducing the overall energy transmission T E without significantly modifying the light transmission, which makes it possible to increase the selectivity of the glass.
• the introduction of copper oxide under the conditions of the float process nevertheless remains difficult as the copper has a tendency to migrate to the surface of the glass where, by reduction, it takes on a brown coloring.
• the content of copper is limited to less than 400 ppm, preferably 250 ppm. Generally, it is not necessary to add copper.
• the optical and energy properties of a glass comprising several coloring agents are difficult to predict. They result from a complex interaction between the various coloring agents, the behavior of which is directly related to their oxidation/reduction state occasioned by the other elements present in the composition.
• the choice of the coloring agents and of their content in the composition is the determining factor in producing the blue glass having the desired optical and energy properties.
• composition according to the invention can additionally comprise additives, for example agents which modify the optical properties in certain parts of the spectrum, in particular in the ultraviolet region, such as CeO 2 , TiO 2 , WO 3 , La 2 O 3 and V 2 O 5 , the total content of these additives not exceeding 2%, preferably 1%.
• additives for example agents which modify the optical properties in certain parts of the spectrum, in particular in the ultraviolet region, such as CeO 2 , TiO 2 , WO 3 , La 2 O 3 and V 2 O 5 , the total content of these additives not exceeding 2%, preferably 1%.
• the redox of the glass is maintained at a value of less than or equal to 0.35, preferably of greater than 0.20 and even better still of less than 0.30, for reasons related essentially to the melting and to the refining of the glass.
• the redox is generally controlled using oxidizing agents, such as sodium sulfate, and reducing agents, such as coke, the relative contents of which are correctly adjusted to produce the desired redox.
• the overall light transmission under illuminant A is greater than or equal to 70% and the energy transmitted is less than 50%, preferably less than 48%, for a thickness of 3.85 mm.
• a composition particularly suited to the production of relatively thin glass, with a thickness of the order of 3.15 mm, comprises the coloring agents below within the following limits, by weight: Fe 2 O 3 (total iron) >0.45% FeO >0.15% CoO 10 to 50 ppm Cr 2 O 3 10 to 300 ppm CuO 0 to 400 ppm
• This thin glass can be paired with another clear glass and the combination can subsequently be rolled to form a laminated glass exhibiting a light transmission LT A of greater than 70% and a selectivity of greater than 1.3 which can be used as a windshield.
• a glass exhibits an excitation purity of less than 9%.
• composition particularly suited to the production of glasses with a thickness of the order of 3.85 mm, of use in forming automobile windows comprises the coloring agents below within the following limits, by weight: Fe 2 O 3 (total iron) >0.4%, preferably >0.45% FeO >0.12%, preferably >0.15% CoO ⁇ 35 ppm Cr 2 O 3 10 to 300 ppm CuO 0 to 400 ppm
• Such a composition makes it possible to obtain a glass exhibiting a light transmission LT A of greater than 60% and a selectivity of greater than 1.3, preferably a light transmission of greater than 70% and a selectivity of greater than 1.4.
• composition particularly suited to the production of glasses with a thickness of the order of 4.85 mm, of use in forming windows for trucks or buses comprises the coloring agents below within the following limits, by weight: Fe 2 O 3 (total iron) >0.3%, preferably >0.4% FeO >0.1%, preferably >0.13% CoO ⁇ 25 ppm Cr 2 O 3 10 to 300 ppm CuO 0 to 400 ppm
• Such a composition makes it possible to obtain a glass exhibiting a light transmission LT A of greater than 60% and a selectivity of greater than 1.3, preferably of greater than 1.4.
• the glasses exhibit a dominant wavelength at least equal to 487 nm.
• the silica is generally maintained within very narrow limits for the following reasons: above approximately 75%, the viscosity of the glass and its ability to devitrify greatly increase, which makes it more difficult to melt it and to cast it on a bath of molten tin, and, below 64%, the hydrolytic resistance of the glass rapidly decreases and the transmission in the visible region also decreases.
• the alkali metal oxides Na 2 O and K 2 O make it easier for the glass to melt and make it possible to adjust its viscosity at high temperatures in order to keep it close to that of a standard glass.
• K 2 O can be used up to approximately 5% as, beyond this level, the problem arises of the high cost of the composition. Furthermore, the increase in the percentage of K 2 O can essentially only be carried out at the expense of Na 2 O, which contributes to increasing the viscosity.
• the sum of the contents of Na 2 O and K 2 O, expressed as percentages by weight, is preferably equal to or greater than 10% and advantageously less than 20%.
• the alkaline earth metal oxides make it possible to adjust the viscosity of the glass to the conditions for the preparation of the glass.
• MgO plays an important role with regard to the viscosity and it can be used up to approximately 5%.
• the complete elimination of MgO, which plays an important role with regard to the viscosity, can be compensated for, at least in part, by an increase in the content of Na 2 O and/or SiO 2 .
• the content of MgO is less than 2%, which has the effect of increasing the absorption capability in the infrared region without harming the transmission in the visible region.
• BaO makes it possible to increase the light transmission and it can be added to the composition according to the invention in a content of less than 5%.
• BaO has a much weaker influence than MgO and CaO on the viscosity of the glass and the increase in its content takes place essentially at the expense of the alkali metal oxides, of MgO and in particular of CaO. Any significant increase in BaO thus contributes to increasing the viscosity of the glass, in particular at low temperatures.
• the glasses according to the invention are devoid of BaO.
• the glass composition in accordance with the invention is capable of being melted under the conditions for the production of float glass. Melting generally takes place in fired furnaces, optionally provided with electrodes, which provide for the heating of the glass in the body of the material by passing an electric current between the two electrodes.
• the calculations of the light transmission (LT A ), of the dominant wavelength ( ⁇ D ) and of the purity (P) are carried out by taking the CIE 1931 (Commission Internationale de l'Eclairage de 1931 [International Commission on Illumination of 1931]) colorimetric reference observer.
• CIE 1931 Commission Internationale de l'Eclairage de 1931 [International Commission on Illumination of 1931]
• the redox is determined using an optical simulation program.
• compositions which appears in table 1 were prepared from the following glass matrix, the contents of which are expressed as percentages by weight, this matrix being corrected with regard to the silica in order to fit the total content of coloring agents which are added: SiO 2 71.00% Al 2 O 3 0.70% CaO 8.90% MgO 3.80% Na 2 O 14.10% K 2 O 0.10%
• the glasses of examples 1, 11, 18 and 30 are examples prepared according to the invention, the compositions of which were measured, whereas the glasses of the other examples are given with their theoretical compositions.
• compositions according to the invention make it possible to obtain blue glasses which satisfy the constraints of overall light transmission (LT A >60%) and which, in addition, exhibit a selectivity at least equal to 1.1 (tables 2 to 4).
• Examples 1 to 42 prepared according to the invention, show that it is possible to obtain glasses exhibiting the desired blue coloring, that is to say a wavelength of between 485 and 490 nm, and a purity of less than or equal to 13% while offering a high light transmission (greater than 60%) and a selectivity at least equal to 1.1.
• These good properties of the glasses result from the combination of the coloring agents in the form of iron, cobalt, nickel and, if appropriate, copper oxides.
• the examples also show that the targeted optical properties can be achieved with a relatively low iron content (less than or equal to 0.51%), which is particularly advantageous when it is a matter of employing the composition in plants for the production of “clear” glass operating according to the float process.
• the glasses obtained from the compositions according to the invention are compatible with the usual techniques for the manufacture of flat glass.
• the thickness of the glass ribbon obtained by coating the molten glass on a tin bath can vary between 0.8 and 10 mm, preferably between 3 and 5 mm, for automobile windows and between 5 and 10 mm for windows intended for the construction industry.
• the window obtained by cutting from the glass ribbon can subsequently be subjected to a bending operation, in particular when it is an automobile window. It can also be subjected to other subsequent treatment operations, for example targeted at coating it with one or more layers of metal oxides for the purpose of reducing the heating thereof by solar radiation and, consequently, of reducing the heating of the passenger compartment of a vehicle fitted with it.

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• General Chemical & Material Sciences (AREA)
• Geochemistry & Mineralogy (AREA)
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• Organic Chemistry (AREA)
• Glass Compositions (AREA)

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• 2001
  • 2001-12-19 FR FR0116455A patent/FR2833590B1/fr not_active Expired - Fee Related
• 2002
  • 2002-12-11 CN CNB028253078A patent/CN1321925C/zh not_active Expired - Fee Related
  • 2002-12-11 EP EP02796909.6A patent/EP1456144B1/fr not_active Expired - Lifetime
  • 2002-12-11 AU AU2002361440A patent/AU2002361440A1/en not_active Abandoned
  • 2002-12-11 KR KR1020047009459A patent/KR100941974B1/ko active IP Right Grant
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  • 2002-12-11 WO PCT/FR2002/004282 patent/WO2003053874A1/fr active Application Filing
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• 2008
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• 2010
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