Dark grey soda-lime glass

DESCRIPTION

DARK GRAY SODED LIME GLASS

The present invention relates to a dark gray soda lime glass composed of glass forming constituents and coloring agents.

The term soda lime glass is used herein in a broad sense and refers to any glass composed of the following constituents (weight percentages):

<td>SiO₂</td><td>60 to 75%</td>

<td>At₂O</td><td>10 to 20%</td>

<td>Dog</td><td>0 to 16%</td>

<td>K₂O</td><td>0-10%</td>

<td>MgO</td><td>0-10%</td>

<td>TO 1₂O₃</td><td>0 to 5%</td>

<td>Good</td><td>0 to 2%</td>

<td>BaO + CaO + MgO</td><td>10 to 20%</td>

<td>K₂O + Na₂O</td><td>10 to 20%</td>

This type of glass is widely used in the field of glazing for buildings or motor vehicles. It is generally manufactured in the form of a strip by a stretching or flotation process. Such a strip may be cut into the sheet of plates which may then be curved or subjected to treatment, for example heat treatment, in order to reinforce the

-7 mechanical properties.

When talking about the optical properties of a glass plate, it is generally necessary to relate these properties to a standard lighting fixture. In the present description, two standard illuminators are used; Illuminant C and Illuminant A confonne defined by the Intemational Commission on Illumination (CIE). Illuminant C stands for average daylight with a color temperature of 6700 K. This lighting fixture is especially useful for evaluating the optical properties of glass for buildings. Illuminant A represents radiation from a Planck radiator at a temperature of about 2856 K. This illuminator represents the light emitted by the headlights of vehicles and is specially designed to evaluate the optical properties of motor vehicle glass. The Intemational Commission on Illumination also published a paper entitled Colometry, Official Recommendations of the CIE (May 1970), which describes a theory whereby the colorimetric coordinates for light of each wavelength of the visible spectrum are defined in order to be represented. in a diagram (known as the CIE trichromatic diagram) having orthogonal axes x and y. This trichromatic diagram shows the position representing light for each wavelength (expressed in nanometers) of the visible spectrum. This position is called the geometric location of the spectrum and the light whose coordinates are situated at this spectrum location is considered to have a degree of excitation purity of 100% for the appropriate wavelength. The geometric location of the spectrum is enclosed by a line called the purple boundary joining the points of the geometric location of the spectrum, whose coordinates correspond to wavelengths of 380 nm (violet) and 780 nm (red). The area included within the geometric location of the spectrum and the purple boundary is that available for the trichromatic coordinates of any visible light. The coordinates of the light emitted by Illuminant C, for example, correspond to χ = 0.3101 and y = 0.3163. This point C is considered to represent white light and because of this it has a degree of excitation purity of zero for any wavelength. Lines can be drawn from point C to the geometric location of the spectrum 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 wavelength corresponding to the line on which it is located. and its distance from point C with respect to the total wavelength line length. From here, the light transmitted by a colored glass plate can be described by its dominant wavelength and by its percent excitation purity.

In fact, the CIE coordinates of the light transmitted by a colored light plate will depend not only on the composition of the glass but also on its thickness. In the present description and claims, all values ​​of the trichromatic coordinates (x, y), excitation purity (P) of the transmitted light dominant wavelength λρ, and the light transmittance of the glass (TL) are calculated at from the specific internal transmission (SIT&gt;.) of a 5 mm thick glass plate. The specific internal transmission of a glass plate is determined solely by the absorption of the glass and may be expressed by Beer-Lambert law, SITx = ε '^ΕΛλwhere Αλ is the absorption coefficient of the glass (in cm '¹) at the wavelength in question and E is the thickness of the glass (in cm). In a first approximation, SH \ can also be represented by the formula (Iv + R₂&gt;.) / (Iià + Rix) where Ι_1λ is the intensity of visible light on the first face of the glass plate, Rp. is the intensity of visible light reflected from this face, Ι₃χ is the light intensity

-Visible transmitted by the second face of the glass plate and R₂&gt;. is the intensity of visible light reflected into the plate by this second face.

In the present description and claims, the following is used:

The total light transmission relative to Illuminant A, measured to a thickness of 4 mm (TLA4). This total transmission is the result of integrating the expression

ZT; .- E_VS; / IE_VS).

between wavelengths 380 and 780 nm, where T; is the wavelength transmission λ, E&gt;. is the spectral distribution of Illuminant A and S; is the sensitivity of the normal human eye as a function of wavelength λ.

f

The total energy transmission, measured to a thickness of 4 mm (TE4). This total transmission is the result of integrating the expression

ΣΤ_λ· Ε_λ/ ΣΕ_λ between 300 and 2150 nm wavelengths, where Εχ is the sun's spectral energy distribution at 30 ° C above the horizon (Moon distribution).

Selectivity, measured at a thickness of 4 mm (SE4), is defined by the ratio (TLA4 / TE4).

The total transmission in ultra violet, measured to a thickness of mm (TUVT4). This total transmission is the result of integrating the expression

Στ_λ· Υ_λ/ Συ_λ between wavelengths 280 and 380 nm, where Ux is the spectral distribution of ultraviolet radiation having passed through the atmosphere as determined by DIN 67507.

The present invention relates in particular to gray glasses with a greenish shade. When the transmission curve of a transparent substance does not vary as a function of the visible wavelength, this substance is described as neutral gray. In the CIE system it has no dominant wavelength and its excitation purity is zero. By extension, a body can be regarded as gray, the spectral curve being relatively flat in the visible region, but nevertheless having poor absorption bands, allowing a dominant wavelength and a degree of purity that is low but not zero to be defined. The gray glass according to the present invention preferably has a degree of excitation purity not exceeding 10%, preferably not exceeding 6% and a dominant wavelength between 480 and 560 nm, corresponding to a greenish shadow.

Gray glazing is generally chosen because of its protective properties relying on sunshine and its use in buildings, especially in countries with a lot of sunshine. Gray glass is also used for marquees or balconies and staircases, as well as for partial glazing in some motor vehicles or train compartments. To protect your interiors from sight, very dark gray glass is mainly used.

The present invention relates to a dark gray glass.

-Selective especially suitable for use as car windows, in particular rear windows or rear side windows.

The present invention features a dark gray soda lime glass composed of glass forming constituents and coloring agents, characterized in that the elements iron, cobalt, selenium and chromium are present as coloring agents in the following proportions (expressed as indicated below). weight percentages of glass):

<td>Faith₂O₃</td><td>0.75 a</td><td> 1,80%</td>

<td>Co</td><td>0.0040 a</td><td> 0,0180%</td>

<td>If</td><td>0.0003 a</td><td> 0,0040%</td>

<td>Cr₂O₃</td><td>0.0010 a</td><td> 0,0100%</td>

the proportions of coloring agents calculated so that the glass has a total energy transmission measured at a glass thickness of 4 mm (TE4) between 15 and 40% and a high selectivity (SE4) of at least

1.2 having a degree of excitation purity not exceeding 10%.

The present invention further features a dark gray soda lime glass of the above composition, achieving a selectivity of at least 1.4%.

In one embodiment, the invention features a dark gray alkaline lime glass composed of glass forming constituents and coloring agents, characterized in that the elements Fe, Cobalt, Selenium and Chromium are present as coloring agents in the following proportions (expressed as (as a percentage by weight of glass):

<img file="PT101913B_D0001.tif" />

<img file="PT101913B_D0002.tif" />

<td>Faith₂O₃</td><td>0.75 to:</td><td> 1,50%</td>

<td>Co</td><td>0.0060 a</td><td> 0,0180%</td>

<td>If</td><td>0.0005 a</td><td> 0,0040%</td>

<td>Cr₂O₃</td><td>0.0010 a</td><td> 0,0100%</td>

the proportions of coloring agents are calculated such that the glass has a total energy transmission measured at a glass thickness of 4 mm (TE4) between 15 and 40% and a high selectivity (SE4) of at least

1.2 with a degree of excitation purity not exceeding 6%.

A tinted glass as defined in the preceding statements of the invention is particularly advantageous because a high selectivity of at least 1.2 associated with poor energy transmission, however, allows light transmission values ​​corresponding to the recommended minimum values ​​for vehicle windows to be obtained. , for security reasons:

Indeed, a glass having an almost similar color can be produced using nickel as the main coloring agent. However, the presence of nickel has some disadvantages, especially when glass has to be produced by the flotation process. In the flotation process, a strip of hot glass is conducted along the surface of a molten tin bath so that its faces are flat and parallel. In order to prevent oxidation of tin on the surface of the bath, which could lead to tin oxide entrainment by this strip, a reducing atmosphere is maintained over the bath. When the glass contains nickel, it is partially reduced by the atmosphere over the tin bath, resulting in a darkening of the glass produced. In addition, the nickel present in the glass may form NiS nickel sulfide. This sulfide exists in various crystalline forms, which are stable within different temperature ranges, creating

-8 the transformation from one to another problems when the glass has to be reinforced by heat tempering treatment, as is the case in the automotive field and also for certain glazing in buildings (balconies, marquees, etc.). The glass according to the invention, which does not contain nickel, is thus particularly suitable for manufacturing by the flotation process as well as for use in architecture or in the field of motor vehicles or others.

The combined presence of iron, selenium, cobalt and chromium-based coloring agents enables the optical and energy properties of gray glass to be controlled according to the invention. The effects of different coloring agents considered individually for the preparation of a glass are as follows (as described in H. Scholtze's German paperback, translated by J. Le Du - Glass Institute - Paris):

Hay: Hay is in fact present in most glass on the market, either as an impurity or deliberately introduced as a coloring agent. The presence of ferric ions (Fe³⁺) gives the glass a slight absorption of visible light having a short wavelength (410 and 440 nm) and a very strong ultraviolet absorption band (380 nm centered absorption band), whereas the presence of ions ferrous (Fe²⁺) causes strong absorption in the infra red (absorption band centered at 1050 nm). Female ions give the glass a slight light yellow color, whereas females ions give a more pronounced bluish green color. The other things being equal, it is the ferrous ions that are responsible for absorption in the range of infrared rays and which determine the transmission of energy (TE). The TE value decreases, which increases selectivity as the concentration of ferrous ions increases. High selectivity is obtained by favoring the presence of ferrous ions over ferric ions.

-9Selenium: The SE Cation⁴⁺ has virtually no coloring effect, whereas the uncharged element Se ° gives a pink tinge. The Anion²It forms a chromophore with ferric ions present and consequently gives a brownish-red color to the glass.

Cobalt: The Co Group^noO4 produces an intense blue tint with a dominant wavelength virtually opposite to that given by the phen selenium chromophore.

Chromium: The presence of the group CrⁱⁿO6 gives rise to absorption bands at 650 nm and gives a light green color. More restrictive oxidation gives rise to the group Cr^vlO₄ which causes a very intense absorption band at 365 nm and gives a yellow tinge.

Cerium: The presence of cerium ions in the composition allows _r'strong absorption is maintained in the ultra violet rays. Cerium oxide exists in two forms; Ce^IV absorbs in ultra violet rays at about 240 nm and Ce¹¹¹ absorbs in the ultra violet rays at about 314 nm.

The optical and energy properties of glass containing various coloring agents thus result from a complex interaction between them, each coloring agent having a behavior which depends strongly on the redox state and therefore on the presence of other elements likely to influence this. state.

We have observed that the proportions of the feiro, cobalt, selenium and chromium coloring agents within the previously defined limits allow for the highest selectivity with the lowest possible energy transmission (TE4) to avoid overheating inside the vehicle.

The glass according to the invention preferably has a total light transmission (TLA4) of between 20 and 50%, which makes it particularly useful for preventing glare from car headlights when used as rear windows or side windows rear of vehicles.

The glass according to the invention also preferably has a total light transmission, measured relative to Illuminant C, at a glass thickness of 5 mm (TLC5) between 20 and 40%, which makes it useful for eliminating bright sunlight when used in buildings.

According to a preferred embodiment of the invention, the gray colored glass is characterized by the presence of the cerium element in an amount corresponding to the following proportions (expressed as a percentage by weight of the glass):

I

CeO₂ 0aI, 0%

In combination with the coloring agents within the previously defined limits, the presence of cerium in such amounts allows for strong absorption in the ultra violet range, with total transmission in the ultra violet range (TUV4) below 15%. This property is particularly advantageous in the automotive field. The weak transmission of ultraviolet radiation prevents aging and discoloration of motor vehicle interiors.

According to a particularly preferred embodiment of the invention, the gray colored glass is characterized by the presence of coloring agents in an amount corresponding to the following proportions (expressed as percentages by weight of the glass):

-1 1-

<td>Faith₂O₃</td><td>0.90 to:</td><td> 1,40%</td>

<td>Co</td><td>0.0080 a</td><td> 0,0130%</td>

<td>If</td><td>0.0005 a</td><td> 0,0030%</td>

<td>Cr₂O₃</td><td>0.0010 a</td><td> 0,0080%</td>

Within the previously defined limits, it is possible to form glass with a full light transmission relative to Illuminant A, measured at a glass thickness of 4 mm (TLA4) between 25 and 45% and a total energy transmission (TE4) situated between 25 and 35%.

If the cerium element is present in such glass, it must be in an amount corresponding to the following proportions (expressed as a percentage by weight of the glass):

CeO₂ 0 to 0.50%

In combination with the coloring agents within the previously defined limits, the presence of cerium in such amounts allows strong absorption in the range of ultra violet rays, corresponding to TUV4 values ​​of less than 10%.

The glass according to the present invention may have a metal oxide coating to reduce its solar radiation heating and, consequently, the interior heating of a vehicle equipped with it.

Particularly useful is a glass corresponding to the previously defined range of more limited concentration of coloring agents as it has optimum light transmission and power transmission properties for use as rear windows and rear side windows of vehicles. In its use in architecture, its aesthetic qualities are combined with significant energy savings associated with lower loads for air conditioning systems.

The glass according to the invention is preferably used in the form of sheets having a thickness of 3 or 4 mm for rear windows and rear side windows of vehicles and more than 4 mm for buildings.

Glass according to the present invention may be manufactured by traditional methods. As raw materials, natural materials, recycled glass, slag or a combination thereof may be used. Coloring agents are not necessarily added in the form indicated, but this way of giving the amounts of added coloring agents in equivalents in the indicated forms corresponds to standard practice. In practice, hay is added to the hay minium source, cobalt is added to the hydrated sulfate source, namely COSO4.7H2O or COSO4.6H2O, selenium is added to the elemental source or source of a selenite, namely Na₂SeO3 or ZnSeO.} And chromium is added to the source of a bichromate, namely K2C12O7. Cerium is added in the form of an oxide or carbonate.

Other elements may be present as impurities in the raw materials used in the manufacture of glass according to the invention (e.g., manganese oxide in proportions in the order of 50 ppm), which may originate from natural materials, recycled glass or slag. but when the presence of these impurities does not give the glass any properties beyond the above defined limits, the glass is deemed to be in accordance with the present invention.

The present invention is illustrated by the following specific examples of compositions.

EXAMPLES 1 TO 17

Table 1 shows the base composition of the glass as well as the constituents of the vitrifiable batch to be melted to produce glasses according to the invention (the amounts being expressed in kilograms per tonne of vitrifiable batch). Table ITa indicates the weights of the components providing the coloring agents in the vitrifiable batch. Table IIb shows the proportions by weight of the coloring agents in the glass produced. These ratios are determined by X-ray fluorescence of the glass and converted to the indicated molecular species. Table III indicates the optical and energy properties corresponding to the definitions given in this description.

TABLE I: BASE GLASS

Base Glass Analysis

<td>SiO₂</td><td>71.5 to 71.9%</td>

<td>TO 1₂O₃</td><td> 0,8%</td>

<td>Dog</td><td> 8,8%</td>

<td>MgO</td><td> 4,2%</td>

<td>At₂O</td><td> 14,1%</td>

<td>K₂O</td><td> 0,1%</td>

<td>only_,</td><td>0.1 to 0.5%</td>

-14Basic Glass Components

<td>Sand</td><td> 572,6</td>

<td>Feldspar</td><td> 29,6</td>

<td>Limestone</td><td> 35,7</td>

<td>Dolomite</td><td> 167,7</td>

<td>At₂CO₃</td><td> 176,7</td>

<td>Sulfate</td><td> 8,1</td>

<td>Nitrate</td><td> 10,1</td>

This mixture may, if desired, contain a reducing agent, namely coke, graphite or slag.

FRAME READ

<td>Example No:</td><td> 1</td><td> 2</td><td> 3</td><td colspan="2"> 4 5</td><td> 6</td><td> 7</td><td> 8</td><td> 9</td>

<td>Faith₂O₃ (kg)</td><td> 7,43</td><td> 8,31</td><td> 8,72</td><td> 9,98</td><td> 8,97</td><td> 9,06</td><td> 10,3</td><td> 7,1</td><td> 8,23</td>

<td>CoO (kg)</td><td> 0,115</td><td> 0,121</td><td> 0,125</td><td> 0,1 15</td><td> 0,105</td><td> 0,104</td><td> 0,045</td><td> 0,054</td><td> 0,121</td>

<td>If (kg)</td><td> 0,037</td><td> 0,037</td><td> 0,053</td><td> 0,027</td><td> 0,035</td><td> 0,043</td><td> 0,006</td><td> 0,023</td><td> 0,023</td>

<td>K₂Cr₂O₇(kg)</td><td> 0,118</td><td> 0,121</td><td> 0,071</td><td> 0,106</td><td> 0,040</td><td> 0,040</td><td> 0,034</td><td> 0,045</td><td> 0,111</td>

<td>Example No:</td><td> 10</td><td> 11</td><td> 12</td><td> 13</td><td> 14</td><td> 15</td><td> 16</td><td> 17</td><td></td>

<td>Faith₂O₃(kg)</td><td> 9,06</td><td> 9,14</td><td> 9,56</td><td> 8,64</td><td> 8,47</td><td> 8,39</td><td>H, 6</td><td> 13,3</td><td></td>

<td>CoO (kg)</td><td> 0,117</td><td> 0,1 18</td><td> 0,1 12</td><td> 0,132</td><td> 0,097</td><td> 0,100</td><td> 0,098</td><td> 0,106</td><td></td>

<td>If (kg)</td><td> 0,045</td><td> 0,045</td><td> 0,055</td><td> 0,047</td><td> 0,023</td><td> 0,006</td><td> 0,010</td><td> 0,017</td><td></td>

<td>K₂Cr₂O₇ (kg)</td><td> 0,025</td><td> 0,030</td><td> 0,020</td><td> 0,057</td><td> 0,078</td><td> 0,071</td><td> 0,044</td><td> 0,055</td><td></td>

-15 FRAME Ilb

<td>Example No:</td><td> 1</td><td> 2</td><td> 3</td><td> 4</td><td> 5</td><td> 6</td><td> 7</td><td> 8</td><td> 9</td>

<td>Faith₂O₃(%)</td><td> 0,956</td><td> 0,061</td><td> 1,110</td><td> 1,260</td><td> 1,140</td><td> 1,150</td><td> 1,3</td><td> 0,917</td><td> 1,051</td>

<td>Co (ppm)</td><td> 110</td><td> 116</td><td> 120</td><td> 110</td><td> 101</td><td> 100</td><td> 43</td><td> 52</td><td> 116</td>

<td>If (ppm)</td><td> 18</td><td> 18</td><td> 26</td><td> 13</td><td> 17</td><td> 21</td><td> 3</td><td> 11</td><td> 11</td>

<td>Cr₂O₃ (ppm)</td><td> 74</td><td> 76</td><td> 45</td><td> 67</td><td> 25</td><td> 25</td><td> 21</td><td> 28</td><td> 70</td>

<td>Example No:</td><td> 10</td><td> 11</td><td> 12</td><td> 13</td><td> 14</td><td> 15</td><td> 16</td><td> 17</td><td></td>

<td>Faith₂O₃(%)</td><td> 1,150</td><td> 1,160</td><td> 1,210</td><td> 1,100</td><td> 1,080</td><td> 1,070</td><td> 1,450</td><td> 1,660</td><td></td>

<td>Co (ppm)</td><td> 112</td><td> 113</td><td> 107</td><td> 126</td><td> 93</td><td> 95</td><td> 94</td><td> 101</td><td></td>

<td>If (ppm)</td><td> 22</td><td> 22</td><td> 27</td><td> 23</td><td> 11</td><td> 3</td><td> 5</td><td> 8</td><td></td>

<td>Cr₂O₃ (ppm)</td><td> 16</td><td> 19</td><td> 13</td><td> 36</td><td> 49</td><td> 45</td><td> 27</td><td> 34</td><td></td>

<td>CeO₂ (%)</td><td></td><td></td><td></td><td> 0,17</td><td> 0,41</td><td> 0,46</td><td></td><td></td><td></td>

TABLE III

<td>Example No:</td><td> 1</td><td> 2</td><td> 3</td><td> 4</td><td> 5</td><td> 6</td><td> 7</td><td> 8</td><td> 9</td>

<td>THE_D(nm)</td><td> 502,7</td><td> 539,7</td><td> 566,0</td><td> 504,1</td><td> 495,6</td><td> 505,6</td><td> 509,6</td><td> 548,3</td><td> 490,4</td>

<td>Purity (%)</td><td> 2,3</td><td> 2,9</td><td> 6,4</td><td> 4,0</td><td> 4,4</td><td> 2,6</td><td> 4,77</td><td> 3,88'</td><td> 7,8</td>

<td>TLA4 (%)</td><td> 33,0</td><td> 31,0</td><td> 27,5</td><td> 32,2</td><td> 36,8</td><td> 34,6</td><td> 48,61</td><td> 50,74</td><td> 35,1</td>

<td>NT4 (%)</td><td> 27,2</td><td> 25,0</td><td> 23,0</td><td> 23,1</td><td> 28,3</td><td> 26,5</td><td> 30,3</td><td> 38,5</td><td> 27,0</td>

<td>TUVtot4 (%)</td><td> 6,0</td><td> 4,9</td><td> 4,0</td><td> 4,1</td><td> 5,3</td><td> 4,9</td><td> 4</td><td> 9</td><td> 6,2</td>

<td>Se4</td><td> 1,21</td><td> 1,24</td><td> 1,20</td><td> 1,39</td><td> 1,30</td><td> 1,27</td><td> 1,60</td><td> 1,32</td><td> 1,30</td>

<td>Example No:</td><td> 10</td><td> 11</td><td> 12</td><td> 13</td><td> 14</td><td> 15</td><td> 16</td><td> 17</td><td></td>

<td>λο (ηιη)</td><td> 556,7</td><td> 568,9</td><td> 565,6</td><td> 516,4</td><td> 495,4</td><td> 489,8</td><td> 493,5</td><td> 539,1</td><td></td>

<td>Purity (%)</td><td> 4,8</td><td> 9,1</td><td> 8,1</td><td> 1,6</td><td> 5,0</td><td> 9,5</td><td> 9,04</td><td> 6,84</td><td></td>

<td>TLA4 (%)</td><td> 31,1</td><td> 28,3</td><td> 29,4</td><td> 31,1</td><td> 40,7</td><td> 43,6</td><td> 40,02</td><td> 30,93</td><td></td>

<td>NT4 (%)</td><td> 24,8</td><td> 23,2</td><td> 22,6</td><td> 25,4</td><td> 32,6</td><td>OO /</td><td> 26,5</td><td> 20,7</td><td></td>

<td>TUVtot4 (%)</td><td> 4,3</td><td> 3,5</td><td> 3,4</td><td> 4,2</td><td> 4,2</td><td> 5,0</td><td> 4,5</td><td> 1,3</td><td></td>

<td>Se4</td><td> 1,25</td><td> 1,22</td><td> 1,30</td><td> 1,23</td><td> 1,25</td><td> 1,30</td><td> 1,51</td><td> 1,49</td><td></td>

Lisbon, 3 September 1996

<img file="PT101913B_D0003.tif" />

JORGE CROSS

Official Industrial Property Agent

VICTOR CORDON STREET, 14-3 °

1200 LISBON