Very dark grey soda-lime glass

DESCRIPTION

VERY DARK GRAY SODED LIME

The present invention relates to a very 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 floating process. Such a strip may be cut into sheets which may then be curved or subjected to treatment, for example heat treatment, in order to reinforce the

-2 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 as 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 that the colorimetric coordinates for the light of each wavelength of the visible spectrum are defined 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 from the geometric location to 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 by 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), the excitation purity (P) of the dominant wavelength λ |&gt; of the transmitted light, and the light transmittance of the glass (TL) are calculated from the specific internal transmission (SITQ of a 5 mm thick sheet of glass. The specific internal transmission of a glass plate is determined solely by the absorption of the glass and may be expressed by the Beer-Lambert Law, SIT&gt;. = e '^{E / V}'where Αχ 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 + Rzx) / (hx-R-ix) where Ιιχ is the intensity of visible light incident on the first face of the glass plate, Rp. is the intensity of visible light reflected from this face, Ι_3λ is the intensity of visible light transmitted by the second face of the glass plate and R₂x 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 for IHuminant A, measured to a thickness of 4 mm (TLA4). This total transmission is the result of integrating the expression

ZT_z-E; .- S_z/ ZE_rs_z between the wavelengths 380 and 780 nm, where T&gt;. is the wavelength transmission λ, E&gt;. is the spectral distribution of IHuminant A and is the sensitivity of the normal human eye as a function of wavelength λ.

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 Ε_λ is the sun's spectral energy distribution at 30 ° C above the horizon (Moon distribution).

The total transmission in ultra violet, measured to a thickness of 4 mm (TUVT4). This total transmission is the result of integrating the expression

Στ_λ· Ϋ; ./ Συ_λ

Between wavelengths 280 and 380 nm, where U \ is the spectral distribution of ultraviolet radiation having passed through the atmosphere as determined by DIN 67507.

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 presenting weak absorption bands, however, 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 an excitation purity of less than 12% and a dominant wavelength of between 460 and 490 nm corresponding to a bluish shade. The glass according to the present invention has a very dark gray tint corresponding to a total light transmission of Illuminant A measured at a thickness of 4 mm (TLA4) of less than 20%.

Gray glass is generally chosen for its sun-protective properties and is known for use in buildings, especially in countries with a lot of sunshine. Gray glazing is also used for marquees or balconies and staircases, as well as for partial glazing in some motor vehicles or train compartments to protect their interiors from view.

The present invention relates to a very dark gray glass, especially suitable for installation on vehicle roofs, for example as a car sunroof or a complete roof panel.

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

<td>Faith₂O₅</td><td>1.00 to 1.65%</td>

<td>Co</td><td>0.017 to 0.030%</td>

<td>If</td><td>0.001 to 0.010%</td>

the proportions of coloring agents are calculated such that the glass has a total light transmission measured against Illuminant A for a glass thickness of 4 mm (TLA4) of less than 20% and a total energy transmission measured for a glass thickness of 4 mm (TE4) of less than 20%.

Such colored glass has a very dark gray appearance and has poor light transmission and energy transmission properties, which are particularly suitable for use as solar radiation shielding, especially for vehicle sun protection ceilings and roof or roof panels. .

In fact, a gray colored glass 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 bath surface, it could lead to entrainment of

Tin 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 can form NiS nickel sulfide. This sulphide exists in various crystalline forms, which are stable within different temperature ranges, creating one-to-one problems when glass has to be reinforced by heat-tempering treatment, as is the case in the automotive field and also for certain vitrifications in buildings (balconies, verandas, etc.). The glass according to the invention, which does not contain nickel, is therefore particularly suitable for manufacture by the float process, as well as the architectural or field use of motor vehicles or others.

The combined presence of iron, selenium and cobalt-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: Iron is in fact present in most glass on the market, either as impurity or deliberately introduced as a coloring agent. The presence of phonic 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 hay²⁺) 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.

Selenium: The SE Cation⁴⁺ has virtually no coloring effect, while the uncharged Seo element 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 CoO Group₄ produces an intense blue color with a dominant wavelength virtually opposite to that given by the iron selenium chromophore.

The optical and energy properties of the glass containing the hay and selenium coloring agents are thus the result of 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 probable elements. to influence this state.

According to a first embodiment of the invention, the coloring agents are present in an amount corresponding to the following proportions (expressed as percentages by weight of the glass):

Faith₂O₃ 1.05 to 1.35%

Co 0.0195 to 0.0225%

If 0.003 to 0.006%

According to another preferred embodiment of the invention, the coloring agents are present in an amount corresponding to the following proportions (expressed as percentages by weight of the glass):

1.35 to 1.65%

0.0175a 0.0205%

0.0015 to 0.0045%

Faith₂Ch

Co Se

The first preferred form of the invention allows the ready formation, given the limited amount of hay present in the composition, of a glass with the desired optical and energy characteristics: light transmission, measured relative to Illuminant A to a glass thickness of 4 mm ( TE4) of less than 20% and energy transmission measured at a glass thickness of 4 mm (TE4) of less than 20%. The other preferred embodiment of the invention facilitates the formation of a very dark gray glass which has a higher selectivity (being selectivity defined as the light to power transmission ratio) as a result of the higher iron content.

The total energy transmission of tinted glass according to the invention as measured at a glass thickness of 4 mm (TE4) is preferably greater than 10%. This limits the heating of the glass by absorption of solar radiation in the case of bright sunlight.

The total energy transmission of the colored glass as measured at a glass thickness of 4 mm (TE4) is preferably less than 15%. Such a total power transmission is particularly well suited to the intended applications, especially vehicle roof panels or glazing panels for buildings in hot countries.

It is desirable that the total light transmission of the glass, measured against Illuminant A to a thickness of 4 mm (TLA4), be greater than 12%, preferably greater than 15%. Such minimum light transmission values ​​provide sufficient vision through the glass.

-10The presence of hay and selenium-based coloring agents within the previously defined limits allows for strong absorption in the range of ultra violet rays. The glass according to the invention preferably has a total transmission in the ultra violet range (TUVT4) of less than 10%, or even less than 5%. This property is particularly advantageous in the automotive field. The weak transmission of ultraviolet irradiation pennite prevent aging and discoloration of the interior of motor vehicles.

Stained glass may contain cerium if the total transmission of glass in the ultraviolet range (TUVT4) is to be further reduced.

The excitation purity of very dark gray glass according to the invention is preferably less than 12%. According to its dominant wavelength, the very dark gray glass according to the invention may have a colored shade, for example green or yellow or preferably bluish.

Such glass is preferably used in the form of slabs, for example slabs with a thickness of 4 or 5 mm, for the manufacture of motor vehicle roof panels, or having thicknesses greater than 4 mm for building panels.

Very dark gray glass may have a coating formed of at least one metal oxide, for example a coating composed of titanium oxide, tin oxide, hay oxide, cobalt oxide, chromium oxide, or a mixture thereof. Such a coated glass exhibits properties of very light transmission of light and energy. In addition, the coatings allow to limit the heating of the glass in bright sun conditions.

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 manner of giving the amounts of coloring agents added in equivalents in the indicated forms corresponds to consistent practice. In practice, iron is added in the form of iron ore, cobalt is added as a hydrated sulfate, namely CoSO4 CI-LO or COSO46H2O, and selenium is added in elemental form or as a selenite, namely At₂If the₃ or ZnSeO₃. Other elements may be present in the form of 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, or small proportions of vanadium or chromium), which may be originating of natural materials, recycled glass or slag, but when the presence of these impurities does not give the glass any properties beyond the limits defined above, 0 glass is deemed to conform to the present invention.

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

EXAMPLES I TO 15

Table 1 indicates 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). Tables IIa, IIb and IIc indicate the dyes to be added to the batch (the amounts being expressed in kilograms for one tonne of vitrifiable raw materials) and the proportions by weight of the coloring agents in the glass produced. These proportions are determined by X-ray fluorescence of the glass and converted to the indicated molecular species. Tables Illa, 111b and IIIc indicate the optical and energy properties corresponding to the definitions given in the present description.

Example 10 refers to a glass according to Example 6, where a layer of titanium dioxide with a thickness of between 50 nm was deposited. This layer was deposited by pyrolysis of an organic titanium compound on the hot glass.

Example 11 refers to a glass according to Example 6, where a layer of hay, cobalt and chromium oxides has been deposited. Such a layer has a thickness of 35 to 45 nm. It contains by weight 62% cobalt oxide, 26% hay oxide and 12% chromium oxide. Such a layer can be readily obtained by pyrolysis of organometallic reagents, such as acetylacetonates, on the glass strip while still at a very high temperature outside a float tank.

TABLE 1: BASE GLASS

Base Glass Analysis

SiO₂

THERE₂O₃

Dog

MgO

At₂O

0,8%

8,8%

4,2%

14,1%

Κ₂Ο

0,1%

Base Glass Constituents

<td>Sand</td><td> 571,3</td>

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

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

<td>Dolomite</td><td> 162,1</td>

<td>At₂CO₃</td><td> 181,1</td>

<td>Sulfate</td><td> 5,0</td>

<td>Nitrate</td><td> 15,2</td>

FRAME READ

Example No: 1

Coloring agents (kg) calculated as:

Faith₂O₃10,48

CoO0.301

Se0.086

Coloring agents (amount by weight on glass) calculated as:

Faith₂O₃ (%)1,32

Co (ppm) 288

If (ppm) 42

<td> 2</td><td> 3</td><td> 4</td><td> 5/</td>

<td> 10,90</td><td> 10,31</td><td> 10,57</td><td> 9,56</td>

<td> 0,251</td><td> 0,251</td><td> 0,194</td><td> 0,209</td>

<td> 0,115</td><td> 0,100</td><td> 0,078</td><td> 0,105</td>

<td> 1,37</td><td> 1,30</td><td> 1,33</td><td> 1,21</td>

<td> 240</td><td> 240</td><td> 186</td><td> 200</td>

<td> 56</td><td> 49</td><td> 38</td><td> 51</td>

-14 FRAME Ilb

<td>Example No:</td><td> 6</td><td> 7</td><td> 8</td><td> 9</td><td> 10</td>

<td>Coloring Agents (kg)</td><td></td><td></td><td></td><td></td><td></td>

<td>calculated on the basis of:</td><td></td><td></td><td></td><td></td><td></td>

<td>Faith₂O₃</td><td> 9,73</td><td> 10,90</td><td> 10,48</td><td> 10,9</td><td> 9,73</td>

<td>CoO</td><td> 0,217</td><td> 0,212</td><td> 0,240</td><td> 0,191</td><td> 0,217</td>

<td>If</td><td> 0,068</td><td> 0,074</td><td> 0,078</td><td> 0,082</td><td> 0,068</td>

Coloring agents (quantity by weight on glass) calculated on

<td colspan="6">dos fonna of:</td>

<td>Faith₂O₃ (%)</td><td> 1,23</td><td> 1,35</td><td> 1,32</td><td> 1,37</td><td> 1,23</td>

<td>Co (ppm)</td><td> 208</td><td> 203</td><td> 230</td><td> 183</td><td> 208</td>

<td>If (ppm)</td><td></td><td> 36</td><td> 38</td><td> 40</td><td> 33</td>

TABLE IIc

Example No:

Coloring agents (kg) calculated as:

12

Faith₂O₃

CoO

If

Coloring agents (amount by weight on glass) calculated as:

Faith₂O₃ (%)

Co (ppm)

If (ppm)

9,7312,00

0,2170,199

0,0680,062

1,231,50

208(90

3330

-15 FRAME Illa

<td>Example No:</td><td> 1</td><td> 2</td><td> 3</td><td> 4</td><td> 5</td>

<td>Glass Properties</td><td></td><td></td><td></td><td></td><td></td>

<td>TL (%)</td><td> 6,8</td><td> 9,2</td><td> 7,8</td><td> 13,1</td><td> 10,3</td>

<td>TLA4 (%)</td><td> 10,7</td><td> 13,8</td><td> 12,2</td><td> 18,1</td><td> 15,2</td>

<td>NT4 (%)</td><td> 15,8</td><td> 18,8</td><td> 15,0</td><td> 19,2</td><td> 18,3</td>

<td>P (%)</td><td>H, 2</td><td> 9,6</td><td> 4,6</td><td> 9,8</td><td> 9,7</td>

<td>AD (nin)</td><td> 476,2</td><td> 581,0</td><td> 580,6</td><td> 74,1</td><td> 578,0</td>

<td>TUVT4 (%)</td><td> 2,1</td><td> 1,9</td><td> 2,4</td><td> 2,5</td><td> 2,2</td>

<td></td><td></td><td>IHB TABLE</td><td></td><td></td><td></td>

<td>Example No:</td><td> 6</td><td> 7</td><td> 8</td><td> 9</td><td> 10</td>

<td>Glass Properties</td><td></td><td></td><td></td><td></td><td></td>

<td>TL (%)</td><td> 13,4</td><td> 10,9</td><td> 9,1</td><td>H, 2</td><td></td>

<td>TLA4 (%)</td><td> 17,8</td><td> 15,4</td><td> 13,2</td><td> 16,0</td><td> 14,1</td>

<td>NT4 (%)</td><td> 17,4</td><td> 13,1</td><td>H, 9</td><td> 14,4</td><td> 15,1</td>

<td>P (%)</td><td> 7,1</td><td> 2,1</td><td> 5,3</td><td>H, 2</td><td></td>

<td>ΔD (nm)</td><td> 486,2</td><td> 533,4</td><td> 487,8</td><td> 570,1</td><td></td>

<td>TUVT4 (%)</td><td> 2,6</td><td> 2,1</td><td> 2,3</td><td> 2,5</td><td> 1,7</td>

-16FRAME IIIc

Example No:

12

Glass Properties

TL (%)

H, 4

TLA4 (%)

9,5 15,8

<img file="PT101911B_D0001.tif" />

<img file="PT101911B_D0002.tif" />

P (%)

<img file="PT101911B_D0003.tif" />

λ D (nm)

513,0

TUVT4 (%) &lt;1 &lt;2

Lisbon, 3 September 1996

<img file="PT101911B_D0004.tif" />

JORGE CROSS

Official Agent of Industrial Property!

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