EP1165452A1

EP1165452A1 - Blue sodiocalcic glass

Info

Publication number: EP1165452A1
Application number: EP00914083A
Authority: EP
Inventors: Dominique Coster; Laurent Delmotte; Marc Foguenne
Original assignee: Glaverbel Belgium SA
Current assignee: AGC Glass Europe SA
Priority date: 1999-02-24
Filing date: 2000-02-21
Publication date: 2002-01-02
Also published as: AU3552500A; US7015162B2; WO2000050352A1; EP1031543A1; US20040259716A1

Abstract

The invention relates to blue coloured sodiocalcic glass. It contains 0.15 to 1.1 wt. % Fe2O3, has a redox that does not exceed 45 %, exhibits a dominant wavelength (μD) in the range of 490 and 493 nm and a luminous transmission (TLA4) in addition to an excitation purity (P) satisfying the relation P⊃-0.3xTLA4+24.5. The inventive glass is particularly suitable for windscreens, side windows and rear-window defoggers in motor vehicles and glazing in buildings.

Description

Blue soda-lime glass.

The present invention relates to a blue colored soda-lime glass, composed of main glass-forming constituents and coloring agents.

The expression "soda-lime glass" is used here in the broad sense and relates to any glass which contains the following constituents (percentages by weight):

Na ₂ 0 10 to 20%

CaO 0 to 16%

Si0 ₂ 60 to 75% κ ₂ o 0 to 10%

MgO 0 to 10%

A1 ₂ 0 ₃ 0 to 5%

BaO 0 to 2%

BaO + CaO + MgO 10 to 20%

K ₂ 0 + Na ₂ 0 10 to 20%

This type of glass finds a very wide use in the field of glazing for the building or the automobile, for example. It is commonly manufactured in the form of a ribbon by the float process. Such a ribbon can be cut into sheets which can then be curved or undergo a treatment to reinforce their mechanical properties, for example thermal quenching.

It is generally necessary to relate the optical properties of a glass sheet to a standard illuminant. In the present description, 2 standard illuminants are used. Illuminant C and illuminant A defined by the International Commission on Lighting (CIE). Illuminant C represents average daylight having a color temperature of 6700 K. This illuminant is especially useful for evaluating the optical properties of glazing intended for buildings. Illuminant A represents the radiation from a Planck radiator at a temperature of around 2856 K. This illuminant represents the light emitted by car headlights and is essentially intended to evaluate the optical properties of glazing intended for the automobile. The Commission Internationale de l'Eclairage has also published a document entitled "Colorimetry, Official CLE Recommendations." (May 1970) which describes a theory that the color coordinates for the light of each wavelength of the visible spectrum are defined so that they can be represented on a diagram having orthogonal axes x and y, called trichromatic diagram CLE. 1931. This trichromatic diagram shows the representative place of the light of each wavelength (expressed in nanometers) of the visible spectrum. This place is called "spectrum locus" and the light whose coordinates are placed on this spectrum locus is said to have 100% purity of excitation for the appropriate wavelength. The spectrum locus is closed by a line called the purple line which joins the points of the spectrum locus whose coordinates correspond to the wavelengths 380 nm (purple) and 780 nm (red). The area between the spectrum locus and the purple line is that available for the trichromatic coordinates of any visible light. The coordinates of the light emitted by the illuminant C for example, correspond to x = 0.3101 and y = 0.3162. This point C is considered to represent white light and therefore has an excitation purity equal to zero for any wavelength. Lines can be drawn from point C to the spectrum locus at any desired wavelength and any point on these lines can be defined not only by its x and y coordinates, but also as a function of the corresponding wavelength to the line on which it is located and its distance from point C related to the total length of the wavelength line. Consequently, the tint of the light transmitted by a sheet of colored glass can be described by its dominant wavelength and its purity of excitation expressed in percent.

CLE coordinates. of light transmitted by a sheet of colored glass will depend not only on the composition of the glass but also on its thickness. In the present description, as well as in the claims, all the values of the excitation purity P and of the dominant wavelength λ _D of the transmitted light are calculated from the specific internal spectral transmissions (TSIχ) of a 5 mm thick glass sheet. The specific internal spectral transmission of a glass sheet is governed solely by the absorption of the glass and can be expressed by the Beer-Lambert law: TSI _λ = e ^"EAλ where A _λ is the absorption coefficient of the glass ( in cm ^"1 ) at the wavelength considered and E the thickness of the glass (in cm). As a first approximation, TSI _λ can also be represented by the formula

where I1 is the intensity of visible light incident on a first face of the glass sheet, R _α is the intensity of visible light reflected by this face, I ₃ is the intensity of visible light transmitted from the second face of the glass sheet and R ₂ is the intensity of the visible light reflected towards the inside of the sheet by this second face.

In the description which follows as well as in the claims, the following are also used: the total light transmission for the illuminant A (TLA), measured for a thickness of 4 mm (TLA4). This total transmission is the result of the integration between the wavelengths of 380 and 780 nm of the expression: Σ T \ .E _λ .S _λ / Σ E _λ .S _λ in which T _λ is the transmission at the wavelength λ, E _λ is the spectral distribution of the illuminant A and S _λ is the sensitivity of the normal human eye as a function of the wavelength λ.

- total energy transmission (TE), measured for a thickness of 4 mm (TE4). This total transmission is the result of the integration between the wavelengths 300 and 2500 nm of the expression: Σ T _λ .E _λ / Σ E _λ in which E _λ is the spectral energy distribution of the sun at 30 ° at above the horizon.

- selectivity (SE), measured by the ratio of the total light transmission for illuminant A and the total energy transmission (TLA / TE).

- total transmission in the ultraviolet, measured for a thickness of 4 mm (TUV4). This total transmission is the result of the integration between 280 and 380 nm of the expression: Σ T _λ .U _λ / Σ U _λ . in which U _λ is the spectral distribution of ultraviolet radiation having passed through the atmosphere, determined in standard DIN 67507.

- The redox ratio, which represents the value of the total Fe2 + / Fe ratio and is obtained by the formula

Fe2 + / total Fe = [24.4495 x log (92 / τ ₁₀₅₀ )] / t-Fe203 where τ ₁₀₅₀ represents the internal specific transmission of the glass of 5 mm at the wavelength of 1050 nm. t-Fe203 represents the total iron content expressed in the form of Fe203 oxide and measured by X-ray fluorescence. The present invention relates in particular to blue glasses. These glasses can be used in architectural applications as well as as glazing for railway cars and motor vehicles. In architectural application sheets of glass 4 to 6 mm thick will generally be used while in the automotive field thicknesses of 1 to 5 mm are commonly used, in particular for the production of monolithic glazing and thicknesses of between 1 and 3 mm in the case of laminated glazing, in particular of windshields, two sheets of glass of this thickness then being secured by means of an interlayer film, generally made of polyvinyl butyral (pvb).

The current demand for blue glazing is moving towards products having, for a given level of light transmission, a marked coloring, that is to say a high excitation purity, even for high levels of light transmission, while offering moderate levels of ultraviolet and infrared radiation transmission.

Thus FR 269526 offers blue glasses exhibiting these qualities. But they are only obtained at the price of a high redox factor, greater than 50%, which makes the glass very absorbent of heat and consequently difficult to melt and to refine in conventional industrial ovens, or of a significant dominant wavelength, at least 494 nm, which corresponds, in particular for a glass having a high light transmission, to a shade of color tending towards green.

The invention eliminates these problematic drawbacks and offers a blue soda-lime colored glass composed of main glass-forming constituents and coloring agents, characterized in that it comprises from 0.15 to 1.1% by weight of Fe ₂ 0 ₃ , present a redox factor not exceeding 45% and offers a dominant wavelength (λ _D ) between 490 and 493 nm and a light transmission (TLA4) as well as an excitation purity (P) satisfying the relation P> - 0.3 x TLA4 + 24.5.

The glass according to the invention therefore has a high purity for a given light transmission and a marked shade of blue color, even for high levels of light transmission, while being easily obtainable in conventional industrial glass furnaces. In addition, the glasses according to the invention have the advantage of combining a blue color with a high selectivity.

Selectivity S> 1.3 is easily reached. This property is particularly advantageous for both automotive and architectural applications because it makes it possible to limit overheating linked to solar radiation and therefore to increase the thermal comfort of the occupants of the vehicle or of the building.

It is advantageous that the glass according to the invention has a redox ratio of less than 40%, which makes it particularly easy to produce. Preferably, the glass according to the invention offers a light transmission greater than or equal to 55%, which makes it usable in most architectural applications or as vehicle glazing.

This glass also preferably has a light transmission and an excitation purity satisfying the relationship P> - 0.3 x TLA4 +

26.5, that is to say an even greater purity at all levels of light transmission, which corresponds well to the aesthetic canons in force today.

Advantageously, the glass according to the invention has a dominant wavelength less than or equal to 492 nm, which corresponds to a very marked blue shade, particularly appreciated aesthetically. Likewise, aesthetic considerations may make it desirable for the dominant wavelength of these glasses to be greater than or equal to 491 nm, so that the shade of blue obtained is especially pleasing to the eye. In certain forms of the invention, the glass offers a selectivity of at least 1.3, preferably at least 1.5, which makes it possible to limit, for a given light transmission, overheating of the volumes delimited by glazing using this glass.

Preferably, the glass according to the invention comprises as coloring agent at least one of the elements chromium, cobalt, titanium, selenium, cerium, manganese and vanadium. The use of these elements makes it possible to adjust the optical properties of the glass optimally and contributes to obtaining a glass offering the shade and the intensity of color sought.

Iron is present in most glasses on the market, either as an impurity, or deliberately introduced as a coloring agent. The presence of Fe ³⁺ gives the glass a slight absorption of visible light of short wavelength (410 and 440 nm) and a very strong absorption band in the ultraviolet (absorption band centered on 380 nm), while the presence of Fe ²⁺ ions causes a strong absorption in the infrared (absorption band centered on 1050 nm). The ferric ions give the glass a slight yellow coloration, while the ferrous ions give a more pronounced blue-green coloration. All other considerations remaining equal, it is the Fe ²⁺ ions which are responsible for the absorption in the infrared domain and which therefore condition TE. The value of TE decreases, which increases that of SE, when the concentration of Fe ²⁺ increases. By favoring the presence of Fe ²⁺ ions with respect to Fe ³⁺ ions, a high selectivity is therefore obtained.

The effects of the various other coloring agents considered individually for the production of a glass are as follows (according to "Le Verre" by H. Scholze - translated by J. Le Dû - Glass Institute - Paris):

Cobalt: The group Co ^u 0 ₄ produces an intense blue coloration with a dominant wavelength almost opposite to that given by the chromophore iron-selenium. Chromium: The presence of the C'Og group gives rise to absorption bands at 650 nm and gives a light green color. Further oxidation gives rise to the group 0 ^ 0 which causes a very intense absorption band at 365 nm and gives a yellow coloring.

Cerium: The presence of cerium ions in the composition makes it possible to obtain a strong absorption in the ultra violet range. Cerium oxide exists in two forms: Ce ^ absorbs in ultra violet around 240 nm and Ce ¹ "absorbs in ultra violet around 314 nm.

Selenium: The cation Se ⁺ has practically no coloring effect, while the uncharged element SeO gives a pink coloration. The anion Se ² forms a chromophore with the ferric ions present and thereby confers a reddish brown color on the glass.

Vanadium: For increasing contents of alkaline oxides, the color changes from green to colorless, which is caused by the oxidation of the group V ^m 0 ₆ to V ^v 0 ₄ . Manganese: appears in the glass in the form of practically colorless Mn "0 _6. The glasses rich in alkali however exhibit a purple color due to the group Mn ^m 0 ₆ .

Titanium: The Ti02 in the glasses gives them a yellow color. For large quantities, the Ti ^m 0 ₅ group can even be obtained by reduction, which colors purple, or even brown.

The energy and optical properties of a glass containing several coloring agents therefore result from a complex interaction between them. Indeed, these coloring agents have a behavior which strongly depends on their redox state and therefore on the presence of other elements likely to influence this state.

Preferably, the glass according to the invention comprises less than 0.1% by weight of Ti0 ₂ . A higher quantity of Ti02 risks giving a yellow coloration which goes against the shade sought here.

It is also preferable that the glass according to the invention contains less than 0.5% by weight of Ce02 among its coloring agents. Indeed, this element absorbing the radiation in the ultraviolet can be used to reduce the transmission of the glass in this range of wavelength, but it involves a displacement of the dominant wavelength towards the green This displacement can be corrected by an increase in the redox ratio of the glass, but this makes it difficult to melt, as indicated above. In addition, Ce is a very expensive element and its use even in quantities not exceeding 1% by weight of Ce02 in the glass can lead to a doubling of the cost price of the raw materials necessary for its manufacture.

Advantageously, the glass according to the invention does not contain more than 0.13% of MnO2 among its coloring agents. Mn02 presents an oxidizing character which risks inducing a green shade by modifying the redox state of the iron, if it is used in higher quantity. It is also desirable that this glass does not contain fluorinated compounds among its coloring agents or at least that these do not represent more than 0.2% by weight of the glass. Indeed, these compounds cause rejections from the oven which are very harmful to the environment and are moreover highly corrosive with respect to the blocks of refractory materials which line the interior of said oven.

On the other hand, it is preferred that the glass according to the invention is obtained from a mixture of main glass-forming constituents offering an MgO concentration of more than 2% because this compound promotes the fusion of said constituents. In preferred forms of the invention, the glass comprises the following percentages by weight of coloring agents, the total amount of iron being expressed in the form of Fe 0 ₃ :

Fe ₂ 0 ₃ 0.3 - 1.1%

FeO 0.10 - 0.30%

Co 0 - 0.0040%

Cr ₂ 0 ₃ 0 - 0.0500%

V 0 - 0.0500%

and has the following optical properties:

55% <TLA4 <85% 36% <TE4 <60% P <12%

Glasses having such characteristics are particularly suitable for a large number of automotive and architectural applications The optical properties obtained correspond to products selective, that is to say having for a given level of light transmission, a low level of energy transmission, which limits the heating of the volumes delimited by glazing produced from such glasses. The transmission purity thus defined is also adequate for such applications.

For certain applications of the invention, in particular in the automotive field, it is preferable that the glasses according to the invention have a light transmission greater than 70%, the lower limit of official standards relating to the side windows before cars, or 75%, for vehicle windshields.

Glasses particularly suitable for the manufacture of glazing for motor vehicles, in particular windshields, include the following percentages by weight of coloring agents, the total amount of iron being expressed in the form of Fe 0 ₃ :

Fe ₂ 0 ₃ 0.3 - 0.7%

FeO 0.10 - 0.20%

Co 0 - 0.0020%

and has the following optical properties:

72% <TLA4 <85% 49% <TE4 <60% 3% <P <9%

Even more preferably, for such applications, the glass according to the invention comprises the following percentages by weight of coloring agents, the total amount of iron being expressed in the form of Fe ₂ 0:

Fe ₂ 0 ₃ 0.4 - 0.6%

FeO 0.11 - 0.16%

Co 0 - 0.0015%

and has the following optical properties:

74% <TLA4 <80% 51% <TE4 <58%

3% <P <7% λ _D <492 nm

For uses of the glass according to the invention as glazing for buildings or as side glazing before vehicles, it comprises the following percentages by weight of coloring agents, the total amount of iron being expressed in the form of Fe ₂ 0 ₃ :

Fe ₂ 0 ₃ 0.4 - 0.8%

FeO 0.16 - 0.23% Co 0 - 0.0030%

and has the following optical properties:

70% <TLA4 <77% 39% <TE4 <50%

4% <P <10%

For such applications, it is particularly preferred that this glass comprises the following percentages by weight of coloring agents, the total amount of iron being expressed in the form of Fe ₂ 0 ₃ :

Fe ₂ 0 ₃ 0.55 - 0.75%

FeO 0.16 - 0.23%

Co 0 - 0.0020%

and has the following optical properties:

70% <TLA4 <74% 41% <TE4 <48% 6% <P <9% λ _D <492 nm

For glass applications according to the invention as rear side glazing for vehicles and certain architectural applications allowing lower light transmission, which goes hand in hand with a reduction in the energy transmission of the glazing, which can be valuable in climates hot, this glass advantageously has a light transmission (TLA4 less than 70% In this case, it is possible and preferable for reasons of ease of manufacture and reduction of the cost of the raw materials necessary for this manufacture, that the glass according to the invention comprises less than 0.01%, preferably less than 0.0050% by weight. of V ₂ 0 ₅ and less than 0.0020%, preferably less than 0.0015% by weight of Cr ₂ 0 ₃ .

For these applications, it is preferred that the glass according to the invention comprises the following percentages by weight of coloring agents, the total amount of iron being expressed in the form of Fe ₂ 0 ₃ :

Fe ₂ 0 ₃ 0.6 - 1.1%

FeO 0.20 - 0.30%

Co 0 - 0.0040%

and has the following optical properties:

55% <TLA4 <69% 30% <TE4 <47% 6% <P <12%

Even more preferably, for the same applications, the glass according to the invention comprises the following percentages by weight of coloring agents, the total amount of iron being expressed in the form of Fe ₂ 0 ₃ :

Fe ₂ 0 ₃ 0.75 - 0.95% FeO 0.22 - 0.28%

Co 0 - 0.0030%

and has the following optical properties:

63% <TLA4 <69%

36% <TE4 <45% 7% <P <11% λ _D <492 nm

The range of light transmission thus defined makes the glass according to the invention particularly useful for avoiding the dazzle by light of automobile headlights when it is used for rear side windows or as a vehicle rear window. The corresponding range of energy transmission brings glass its high selectivity.

In order to facilitate the melting of the glasses according to the invention, it is desired that they include, among their coloring agents, less than 1.0% by weight of Fe ₂ 0 ₃ .

The glass according to the invention can be coated with a layer of metal oxides reducing its heating by solar radiation and consequently that of the passenger compartment of a vehicle using such glass as glazing.

The glasses according to the present invention can be manufactured by traditional methods. As raw materials, natural materials, recycled glass, slag or a combination of these can be used. The dyes are not necessarily added in the form indicated, but this manner of giving the quantities of coloring agents added, in equivalents in the forms indicated, corresponds to current practice. In practice, iron is added in the form of a hotpot, cobalt is added in the form of hydrated sulphate, such as CoSO ₄ .7H ₂ 0 or CoSO ₄ .6H ₂ 0, chromium is added in the form of dichromate such as K ₂ Cr ₂ 0 ₇ . Cerium is introduced in the form of oxide or carbonate. As for vanadium, it is introduced in the form of sodium oxide or vanadate. Selenium, when present, is added in elemental form or in the form of selenite such as Na ₂ Se0 ₃ or ZnSe0 ₃ .

Other elements are sometimes present as impurities in the raw materials used to manufacture the glass according to the invention, whether in natural materials, in recycled glass or in slag, but when these impurities do not give the glass properties outside the limits defined above, these glasses are considered to comply with the present invention. The present invention will be illustrated by the specific examples of optical properties and compositions which follow.

EXAMPLES 1 to 59

Table I gives by way of nonlimiting indication the basic composition of the glass as well as the constituents of the vitrifiable charge to be melted to produce the glasses according to the invention. Table II gives the proportions of coloring agents and the optical properties of glasses according to the invention. Table III gives, by way of comparison with the glasses according to the invention, examples of blue glasses tending towards green. The above-mentioned proportions are determined by X-ray fluorescence of the glass and converted into the molecular species indicated. The batch can, if necessary, contain a reducing agent such as coke, graphite or slag or an oxidizing agent such as nitrate. In this case, the proportions of the other materials are adjusted so that the composition of the glass remains unchanged.

TABLE I

TABLE II

N ° Fe203 FeO Redox Co TLA4 TE4 TUV4 SE4 λ _D P ex. (%) (%) (%) (ppm) (%) (%) (%) (nm) (%)

1 0.89 0.22 27.8 20 63.8 40.3 16.5 1.58 491.3 8.7

2 0.87 0.26 33.2 19 62.2 37.4 17.6 1.66 490.3 10.3

3 0.62 0.14 25.2 17 72.4 52.2 25.8 1.38 490.3 6.5

4 0.76 0.21 31.0 16 66.2 42.3 20.2 1.56 490.2 9.0

5 0.38 0.08 23.6 9 80.3 64.5 36.5 1.24 490.0 4.2

6 0.39 0.08 24.5 8 79.7 63.1 35.1 1.26 490.3 4.4

7 0.51 0.12 27.1 7 76.6 56.2 30.8 1.36 491.0 5.3

8 0.40 0.08 22.7 5 81.5 64.8 35.3 1.25 492.9 3.3

9 0.50 0.13 28.6 4 77.7 55.8 30.8 1.39 492.3 4.9

10 0.50 0.12 26.6 10 76.9 56.8 31.4 1.35 490.2 5.3

11 0.50 0.118 26.2 6 78.2 57.5 31.4 1.36 492.2 4.4

12 0.48 0.118 27.3 4 78.9 57.8 32.2 1.36 492.5 4.3

13 0.56 0.132 26.1 8 76.2 54.9 29.0 1.38 492.0 5.0

14 0.56 0.132 26.1 12 75.0 54.5 29.0 1.37 490.3 5.8

15 0.50 0.134 29.7 5 77.3 55.3 31.5 1.39 491.4 5.2

16 0.49 0.125 28.3 7 77.4 56.4 31.8 1.37 490.9 5.2

17 0.48 0.125 28.9 4 78.4 56.7 32.2 1.38 491.9 4.7

18 0.55 0.142 28.6 4 76.7 54.1 29.5 1.41 492.9 4.9

19 0.56 0.167 33.1 4 75.0 50.8 29.2 1.47 491.5 6.1

20 0.55 0.18 36.3 4 74.2 49.1 29.6 1.51 490.9 7.0

21 0.57 0.18 35.0 6 73.5 48.9 28.8 1.50 490.4 7.0

22 0.50 0.135 30.0 4 77.5 55.2 31.5 1.40 491.8 5.1

23 0.48 0.13 30.0 6 77.4 55.8 32.3 1.38 490.4 5.7

24 0.46 0.13 31.4 4 78.0 55.9 33.1 1.39 491.1 5.4

25 0.46 0.13 31.4 6 77.5 55.7 33.1 1.39 490.1 5.7

26 0.80 0.2 27.7 14 67.2 44.8 19.9 1.49 491.7 7.7

27 0.80 0.2 27.7 19 65.7 44.3 20.0 1.48 490.4 8.7

28 0.79 0.22 30.9 16 65.8 43.0 20.5 1.52 490.3 8.7

29 0.78 0.23 32.7 12 66.6 42.6 20.9 1.56 491.1 8.6

30 0.78 0.23 32.7 6 68.4 43.2 20.9 1.58 492.8 7.4

31 0.85 0.27 35.3 6 65.8 38.8 18.2 1.69 492.7 8.3

32 0.85 0.27 35.3 11 64.3 38.3 18.2 1.68 491.4 9.3

33 0.85 0.26 33.9 15 63.6 38.7 18.2 1.64 490.9 9.5 N ° Fe203 FeO Redox Co TLA4 TE4 TUV4 SE4 λ _D P ex. (%) (%) (%) (ppm) (%) (%) (%) (nm) (%)

34 0.85 0.28 36.6 15 62.7 37.0 18.3 1.69 490.3 10.0

35 0.90 0.28 34.5 15 62.2 36.4 16.2 1.70 491.0 10.0

36 0.65 0.16 27.3 15 71.2 49.5 24.6 1.43 490.4 7.0

37 0.66 0.16 26.9 12 72.0 49.6 24.2 1.45 491.6 6.3

38 0.67 0.17 28.1 14 70.8 48.2 23.8 1.46 490.3 6.9

39 0.64 0.18 31.0 14 70.4 47.4 24.9 1.48 490.3 7.8

40 0.60 0.17 31.4 10 72.6 49.3 26.7 1.47 490.2 7.1

41 0.60 0.17 31.4 4 74.3 49.8 26.6 1.49 492.7 5.7

42 0.65 0.19 32.4 4 72.8 47.2 24.7 1.54 492.9 6.2

43 0.64 0.2 34.7 9 70.8 45.7 25.1 1.54 490.4 8.0

44 0.70 0.22 34.9 4 70.7 43.6 22.8 1.62 492.6 7.0

45 0.62 0.17 30.4 14 71.2 48.7 25.8 1.46 490.2 7.7

46 0.71 0.19 29.7 8 71.0 46.2 22.2 1.53 492.7 6.4

47 0.98 0.255 28.9 15 62.5 36.7 13.2 1.70 492.7 8.5

48 0.98 0.27 30.6 18 61.1 35.3 13.3 1.72 491.6 9.6

49 1.05 0.27 28.5 18 60.1 33.8 10.5 1.77 492.4 9.2

50 1.07 0.3 31.1 22 57.5 31.0 9.78 1.85 491.2 10.8

51 1.08 0.33 33.9 20 57.0 29.0 9.45 1.96 491.3 11.2

52 1.08 0.34 34.9 25 55.1 27.8 9.48 1.98 490.4 12.4

TABLE III

53 0.38 0.08 23.1 4 82.0 65.4 36.7 1.25 493.3 3.0

54 0.52 0.118 25.2 4 78.6 57.5 30.6 1.36 493.8 3.8

55 0.55 0.132 26.6 4 77.4 55.4 29.4 1.39 493.7 4.3

56 0.80 0.2 27.7 8 68.9 45.4 19.9 1.51 493.7 6.5

57 0.86 0.25 32.3 6 66.6 40.3 17.7 1.65 493.5 7.5

58 0.65 0.16 27.3 6 73.9 50.3 24.6 1.46 493.8 5.2

59 0.95 0.25 29.2 12 64.0 38.0 14.4 1.68 493.3 7.9

Claims

1. Blue soda-lime colored glass composed of main glass-forming constituents and coloring agents, characterized in that it comprises from 0.15 to 1.1% by weight of Fe ₂ 0 ₃ , has a redox factor not exceeding 45% and offers a dominant wavelength (λ _D ) between 490 and 493 nm and a light transmission (TLA4) as well as an excitation purity (P) satisfying the relation P> - 0.3 x TLA4 + 24.5.

2. Colored glass according to claim 1, characterized in that it has a light transmission (TLA4) greater than or equal to 55%.

3. Colored glass according to any one of claims 1 to

2, characterized in that it has a light transmission (TLA4) and an excitation purity (P) satisfying the relation P> - 0.3 x TLA4 + 26.5.

4. Colored glass according to any one of claims 1 to

3, characterized in that it has a dominant wavelength (λ _D ) less than or equal to 492 nm.

5. Colored glass according to any one of claims 1 to

4, characterized in that it has a dominant wavelength (λ _D ) greater than or equal to 491 nm.

6. Colored glass according to any one of claims 1 to

5, characterized in that it comprises, as coloring agents, a compound of at least one of the elements Cr, Ce, Co, Se, V, Ti, Mn.

7. Colored glass according to any one of claims 1 to

6, characterized in that it comprises, among its coloring agents, less than 0.1% by weight of Ti02.

8. Colored glass according to any one of claims 1 to

7, characterized in that it comprises less than 0.5% by weight of Ce02.

9. Colored glass according to any one of claims 1 to

8, characterized in that it comprises less than 0.13% by weight of Mn02.

10. Colored glass according to any one of claims 1 to

9, characterized in that it comprises the following percentages by weight of coloring agents, the total amount of iron being expressed in the form of Fe ₂ 0 ₃ :

Fe ₂ 0 ₃ 0.3 - 1.1%

FeO 0.10 - 0.30%

Co 0 - 0.0040%

Cr 0 - 0 0500% V ₂ 0 ₅ 0 - 0.0500%

and has the following optical properties:

55% <TLA4 <85% 36% <TE4 <60% P <12%

11. Colored glass according to any one of claims 1 to 10, characterized in that it has a light transmission (TLA4) greater than or equal to 70%.

12. Colored glass according to claim 10, characterized in that it comprises the following percentages by weight of coloring agents, the total amount of iron being expressed in the form of Fe 0 ₃ :

Fe ₂ 0 ₃ 0.3 - 0.7%

FeO 0.10 - 0.20%

Co 0 - 0.0020%

and has the following optical properties:

72% <TLA4 <85% 49% <TE4 <60% 3% <P <9%

13. Colored glass according to claim 12, characterized in that it comprises the following percentages by weight of coloring agents, the total amount of iron being expressed in the form of Fe ₂ 0 ₃ :

Fe ₂ 0 ₃ 0.4 - 0.6%

FeO 0.11 - 0.16%

Co 0 - 0.0015%

and has the following optical properties:

74% <TLA4 <80% 51% <TE4 <58%

3% <P <7% λ _D <492 nm

14. Colored glass according to claim 10, characterized in that it comprises the following percentages by weight of coloring agents, the total quantity of iron being expressed in the form of Fe ₂ 0 ₃ :

Fe ₂ 0 ₃ 0.4 - 0.8%

FeO 0.16 - 0.23%

Co 0 - 0.0030%

and has the following optical properties:

70% <TLA4 <77% 39% <TE4 <50% 4% <P <10%

15. Colored glass according to claim 14, characterized in that it comprises the following percentages by weight of coloring agents, the total amount of iron being expressed in the form of Fe ₂ 0 ₃ :

Fe ₂ 0 ₃ 0.55 - 0.75%

FeO 0.16 - 0.23%

Co 0 - 0.0020%

and has the following optical properties:

70% <TLA4 <74% 41% <TE4 <48% 6% <P <9% λ _D <492 nm

16. Colored glass according to claim 10, characterized in that it has a light transmission (TLA4) of less than 70%.

17. Colored glass according to claim 16, characterized in that it comprises less than 0.01%, preferably less than 0.0050% by weight of V ₂ 0 ₅ and less than 0.0020%, preferably less than 0.0015% by weight of Cr ₂ 0 ₃ .

18. Colored glass according to any one of claims 16 to 17, characterized in that it comprises the following percentages by weight of coloring agents, the total amount of iron being expressed in the form of Fe ₂ 0 ₃ :

Fe ₂ 0 ₃ 0.6 - 1.1%

FeO 0.20 - 0.30%

Co 0 - 0.0040%

and has the following optical properties:

55% <TLA4 <69% 30% <TE4 <47% 6% <P <12%

19. Colored glass according to claim 18, characterized in that it comprises the following percentages by weight of coloring agents, the total amount of iron being expressed in the form of Fe ₂ 0 ₃ :

Fe ₂ 0 ₃ 0.75 - 0.95%

FeO 0.22 - 0.28%

Co 0 - 0.0030%

and has the following optical properties:

63% <TLA4 <69% 36% <TE4 <45% 7% <P <11% λ _D <492 nm

20. Colored glass according to any one of claims 1 to

19, characterized in that it comprises less than 1.0% by weight of Fe ₂ 0 ₃ .

21. Colored glass according to any one of claims 1 to

20, characterized in that it forms a glazing for an automobile.