Colored glass composition for the manufacture of glazing

ES 2 158 987 T3

DESCRIPTION

Accessory for windows mounted on a motor vehicle.

The present invention relates to the composition of a colored glass for the manufacture of a glass that can be specially designed to be mounted on a motor vehicle. More particularly, its objective is that of a glass with a composition that allows making a glass that can form the rear side windows and the rear windows of a motor vehicle.

Automobile manufacturers offer tinted windows to their customers, not only out of a concern for aesthetics but also because of the functional role they can perform; this is, especially the improvement of visibility in critical lighting conditions, and / or the comfort of the passengers.

With regard to this last aspect, the proportion of the glazed surface increases every year with the new models; therefore, from now on, the greenhouse effect is an important factor to take into account in the air conditioning of the vehicle. One of the means to reduce this effect consists in the development of glass with weak transmission for near infrared radiation, but whose transmission for the visible spectrum - although lower than that of classic windshields - remains acceptable for passengers.

US-A-4 104 076 proposes glasses with iron, cobalt, chromium and / or uranium oxides and, optionally, also with selenium. These glasses are classified into two categories: bronze glasses with a light transmission factor between 40 and 55%; and gray glasses for which this factor is between 35 and 45%. These glasses, specifically intended for making glass for buildings, have a global energy transmission factor of less than 50% for a thickness of 6.2 mm.

Patent application EP-A-0 349 909 proposes glasses with a grayish tint composed of iron and cobalt oxides to which at least 30 ppm of selenium is added. These glasses are characterized by a thickness of 5.56 mm, by a light transmission factor of between 5 and 20% and a global energy transmission factor of less than 40%. All glasses presented by way of example have an energy transmission factor higher than the light transmission factor.

Patent application EP-AO 482 535 proposes dark tinted glasses adapted in particular for the realization of roofs of motor vehicles . Iron and cobalt oxides accompanied by selenium color these glasses that are characterized by a weak light transmission (equal to or less than 32%) and a very weak energy transmission (less than 15%) with a thickness of 3.9 mm.

US Pat. No. 4,190,452 discloses neutral bronze glasses whose coloration is due to iron and cobalt oxides, selenium and, eventually, nickel and chromium oxides. These glasses, for a thickness of 3 mm, are characterized by a light transmission greater than 70%, an excitation purity between 2 and 6% and a dominant wavelength that varies between 570 and 580 nm.

US-A 4 866 010 describes glasses that can be used both for buildings and in the automotive industry. These are blue glasses whose coloration is obtained by means of iron and cobalt oxides and by selenium. For a thickness of 6.35 mm, they have a light transmission of the order of 54%.

Patent FR.A 2 074 983 describes gray colored glasses whose coloring agents are also iron and cobalt oxides accompanied by selenium. These glasses have a low level of excitation purity (less than 1.5%), have a thickness of 5 mm, a light transmission and an energy transmission between 57 and 63%.

US patent 3 296 004 describes neutral bronze glasses specially intended for use in the construction of buildings. For a thickness of 6.35 mm, they have a light transmission between 48 and 56% and an energy transmission of less than 50%. The coloration of these glasses is due to the presence of selenium, iron oxide and cobalt.

The present invention aims to provide accessory glasses mounted on a motor vehicle comprising a windshield, front and rear side windows and a rear window, in which the rear side windows and the window are manufactured from colored glass. as a whole and which have, for a given thickness, a moderate global light transmission and a corresponding lower global energy transmission.

The invention also aims to provide an accessory glass in which the glass of the late2

ES 2 158 987 T3 rear rails and the rear window are made from colored glasses of different compositions.

According to this invention, these objectives are achieved thanks to a glass accessory according to claim 1.

The compounds that form these crystals may contain other constituents in very low amounts, coming from compounds added to the vitrifiable mixture to facilitate the refinement of the crystal. It is for example the case of SO₃ from the decomposition of the sulfate added to the mixture.

The glasses that form these crystals can be made in classic furnaces and transformed into a continuous belt by the well-known technique of floating glass in tin bath.

The glasses that form these crystals have, under an illuminator C, a low excitation purity, generally less than 15% and often less than 12%.

The transmissive characteristics of the glasses that form these crystals as well as their characteristic wavelengths under an illuminator C are governed by their oxide-reducing state. Following the present invention, between 16 and 55% of the total iron expressed as Fe2O3 may be as ferrous oxide. More generally, 20 to 40% of the total iron is in the form of ferrous oxide.

The glasses that form these crystals have grayish tints and more or less neutral colors that can vary from blue / green to green / yellow, passing through all intermediate shades, corresponding to characteristic wavelengths under an illuminator C between 490 and 560 nm. .

The glasses that form these crystals have the desired transmission characteristics when using iron and cobalt oxides as coloring agents; and adding chromium oxide and eventually selenium, the latter has the effect of reducing the purity of excitation.

The glasses that make up these stained-glass windows may comprise only a part, or all of these coloring agents, in proportions duly chosen according to the desired characteristics.

Thus, the glasses that form these crystals can comprise as coloring agents iron and cobalt oxides, and optionally selenium. The amounts by weight of the preferred glass tinting agents in the present invention can vary depending on the properties desired.

Glasses with a grayish tint and characterized by a high light transmission factor (TLA> 40%) comprise the following tinting agents in the weight limits defined as follows:

<td></td><td>(I)</td>

<td>Faith₂OR₃ (total iron)</td><td>0.45 to 1%</td>

<td>CoO</td><td>0.001 to 0.01%</td>

<td>I know</td><td>0.0002 to 0.002%</td>

Glasses that also present a grayish tint but are characterized by a weaker light transmission factor (TLA &lt;40%) and a TE factor clearly lower than that of glasses (i), comprise the following coloring agents in the weight limits defined as follows:

<td></td><td>(II)</td>

<td>Faith₂OR₃ (total iron)</td><td> 1,8%</td>

<td>CoO</td><td>0.005 to 0.02%</td>

<td>I know</td><td>0.0005 to 0.0025%</td>

Among the glasses belonging to this family but which eventually do not contain selenium, one can distinguish the glasses that present a high TLA factor (&gt; 40%) and a relatively low TE factor. Such

ES 2 158 987 T3 glasses comprise the coloring agents defined below within the following weight limits:

<td></td><td>(III)</td>

<td>Faith₂OR₃ (total iron) CoO</td><td>0.8 to 1.8% 0.001 to 0.01%</td>

Always in the category of glasses that eventually do not contain selenium, it is also possible to define those that present a TLA factor and a TE factor clearly lower than that of the preceding glasses (III). These glasses have a very high content of iron oxides associated with cobalt oxide in the following proportions by weight:

<td></td><td>(IV)</td>

<td>Faith₂OR₃ (total iron) CoO</td><td>1? 3 to 2? 5% 0.005 to 0.015%</td>

The crystals (III) and (IV) can, of course, contain selenium, in the general limits defined above.

To prepare the glasses of the invention, we use as a base composition a traditional glass composition of the flat glass industry, in which the coloring agents are added according to the proportions that allow obtaining, for a given thickness, the optical and optical characteristics. the desired appearance.

The base glass chosen has the following weight composition:

<td>SiO2</td><td> 72,1%</td>

<td>To the₂O3</td><td> 0,74%</td>

<td>CaO</td><td> 8,90%</td>

<td>MgO</td><td> 3,79%</td>

<td>Na₂OR</td><td> 14,16%</td>

<td>K2O</td><td> 0,11%</td>

<td>SO3</td><td> 0,20%</td>

Coloring agents are added to this glass to the detriment of silicon.

The attached table presents a series of glass composition examples that illustrate the invention. The amounts of the coloring agents are expressed in percentages by weight. The values ​​of the different characteristics of these crystals have been measured in sheets of 3.85 millimeters thick. The level of purity reached by some glasses according to the invention is remarkable in relation to the low amount of selenium present in these glasses. Following the invention, for all the glasses the Fe2O3 (total) / Se ratio is higher than 200.

As indicated above, the glasses according to the invention can be made into continuous ribbons by the floating glass technique. The glass loamines obtained by cutting this tape have thicknesses that vary more or less between 2 and 8 mm. These glass sheets can be used alone or combined with an uncolored sheet to make glass that can be mounted on a motor vehicle at the location of the rear sides and the rear window.

These crystals can be assembled by associating them in an accessory with other crystals that form the windshield and the front sides. This is how a motor vehicle accessory can be made up of crystals whose global luminous transmission factor under illuminator A, for a given thickness, decreased when passing from the windshield to the rear window.

ES 2 158 987 T3

The glasses obtained from the glasses obtained according to the present invention can be used very conveniently in the framework of an accessory for a motor vehicle.

In this way, the rear side windows, whether they are movable side windows or the fixed rear windows called custody windows, could be made from glasses that, for a thickness of 3.85 mm, have a global light transmission factor under an illuminator A between 30 and 60%. They could be associated with the rear windows made from crystals that, for an ideal thickness, have a global light transmission factor under Illuminator A of between 20 and 45%.

An accessory of this type could be made from reference crystals Ex.5 and Ex.2 in the attached table. The crystals formed by the Ex.5 glass were used for the rear sides, the glass formed by the Ex.2 glass constituted the rear window.

PICTURE

<td></td><td>EX.1</td><td>EX.2</td><td>EX.3</td><td>EX.4</td><td>EX.5</td><td>EX.6</td><td>EX.7</td><td>EX.8</td>

<td>Faith₂OR₃ (total iron)</td><td> 1,5</td><td> 1,65</td><td> 1,95</td><td> 0,62</td><td> 1,50</td><td> 1,2</td><td> 1,25</td><td> 1,84</td>

<td>CoO</td><td> 0,0122</td><td> 0,0110</td><td> 0,0066</td><td> 0,0055</td><td> 0,0058</td><td> 0,0032</td><td> 0,0102</td><td> 0,006</td>

<td>I know</td><td> 0,0013</td><td> -</td><td> -</td><td> 0,0009</td><td> -</td><td> -</td><td> 0,0015</td><td> -</td>

<td>Cr₂OR₃</td><td> -</td><td> -</td><td> -</td><td> -</td><td> -</td><td> -</td><td> -</td><td> -</td>

<td>Ródox</td><td> 0,27</td><td> 0,33</td><td> 0,25</td><td> 0,29</td><td> 0,24</td><td> 0,29</td><td> 0,28</td><td> 0,31</td>

<td>TLa (%)</td><td> 35</td><td> 35</td><td> 35</td><td> 55,7</td><td> 45,8</td><td> 55,0</td><td> 33,5</td><td> 34,1</td>

<td>Tea (%)</td><td> 25,3</td><td> 18,7</td><td> 17,8</td><td> 44,9</td><td> 26,8</td><td> 32</td><td> 21,6</td><td> 16,8</td>

<td>λD (c) (nm)</td><td> 496</td><td> 488</td><td> 501</td><td> 505</td><td> 490</td><td> 495</td><td> 531</td><td> 494</td>

<td>Pc (%)</td><td> 3,2</td><td> 17,4</td><td> 7,6</td><td> 1,1</td><td> 10,8</td><td> 6,3</td><td> 2,8</td><td> 11,7</td>