Glazing pane for screening solar radiation and process for producing thereof

DESCRIPTION

GATED PANEL PROPERTIES

PROTECTION AGAINST SOLAR RADIATION

The present invention relates to a glazing panel having solar radiation protection properties. The panel according to the invention takes the form of a substrate carrying a pyrolytic coating formed of tin and antimony spray.

Transparent reflective solar control windows have become widely used in vehicle windows, where the aim is to protect the occupants of the vehicle from solar radiation. This type of glazing has been used in side-haul haul carriages and in road vehicles for side, rear and roof windows. Also proposed is its use to form the entire roof of motor vehicles. This type of glass serves to provide protection against solar radiation through reflection and / or absorption and by eliminating the dazzling effects of intense sunlight, thus promoting an effective protection against dazzle, improving visual comfort. and reducing eye fatigue.

The properties of the coated substrate analyzed herein are based on standard definitions from the International Lighting Commission - Conimission Inlernalionale de 1'Eclairage (C.IE).

The standard lighting agents referred to herein are the

CIE Type C and A Lighting Agents. The CIE Lighting Agent (commonly used to evaluate the optical properties of building glazing panels) represents medium intensity daylight with a color temperature of 6,700 ° K. Lighting Agent A (which is equivalent to light emitted by car headlights and is therefore generally used to evaluate the optical properties of motor vehicle glazing) represents the radiation of a Planck radiation agent at a temperature of about of 2,856 ° K.

Light transmittance (TL) is the light flux transmitted through a substrate as a percentage of the incident light flux.

Light reflectance (RL) is the light flux reflected from a substrate as a percentage of the incident light flux.

Energy transmission (TE) is the total radiant energy transmitted directly through a substrate as a percentage of the incident radiant energy.

Energy reflection (RE) is the radiant energy reflected from a substrate as a percentage of the incident radiant energy.

The solar factor (FS) is the ratio of the sum of the total energy transmitted directly through a substrate (TE) to the energy that is absorbed and re-radiated on the opposite side to that which faces the energy source ( AE) as a proportion of the total radiant energy incident on the substrate.

V

The selectivity of the coated substrate concerns the balance between light transmission and energy transmission. In the case of building glass this is often defined as the ratio of light transmittance to the solar factor (TL / FS), but in the case of vehicle glass it usually refers to the relationship between light transmittance and power transmission (TL). /YOU).

The dominant wavelength (λ ') is the peak wavelength in the range transmitted or reflected by the coated substrate.

The purity (p) of the substrate color refers to the excitation purity measured with Illumination Agent C. This parameter is specified according to a linear scale where a defined white light source has a purity of zero and a pure color. has a purity of 100%. The purity of the coated substrate is measured from the opposite side to the coated side.

Emissivity (ε) is the relationship between the energy emitted by a given surface at a given temperature and the energy emitted by a perfect emitter (blackbody with an emissivity of 1.0) at the same temperature.

From a technical point of view it is desirable that under insolation the windowpanes do not allow too high a proportion of the total incident solar radiation to pass so that the interior of the vehicle or building does not become overheated. The transmission of total incident solar radiation may be expressed in terms of the solar factor (defined above). In the case of vehicles, the main energy factor to be taken into consideration is the total direct transmitted energy (TE) as the energy that is absorbed

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again and again irradiated (AE) is dissipated by the vehicle's travel movement.

Applicant's previous patent GB 2200139 describes and claims a method of forming a pyrolytic tin oxide coating on a heated glass substrate by spraying with a solution containing a tin compound and additives which produce in the coating. fluorine and materials such as antimony, arsenic, vanadium, cobalt, zinc, cadmium, tungsten, tellurium and manganese, in order to give the coating a low emissivity and a specific low internal turbidity factor. Despite having many desirable properties, the resulting coating fails to achieve the combination of properties now sought for solar radiation resistant vehicle window panes.

It is an object of the present invention to provide a glazing panel having a high level of solar radiation shielding properties in combination with other desirable light transmission and high selectivity properties.

We have found that this and other useful objects can be achieved by means of a glassy substrate carrying a thick pyrolytically sprayed coating comprising tin and antimony oxides in a specific relative proportion.

Accordingly, in accordance with the present invention, there is provided a glazing panel comprising a glassy substrate carrying a spray-formed tin oxide / pyrolytic antimony coating layer having a thickness of at least

400 containing tin and antimony at a molar ratio Sb / Sn of between 0.05 and 0.5, whereby the coated substrate has a light transmittance (TL) of less than 35% and a selectivity (TL / TE) of at minus 1.3.

A number of proprietary techniques for coating a glassy substrate are known, including pyrolysis and cathodic sputtering (a process whereby atoms in the gas will be removed from the cathode by positive ion bombardment, such atoms will deposit on any surface and be used to coat dielectrics with thin films of various metals). Pyrolysis generally has the advantage of producing a hard coating, which avoids the need for a protective layer. Pyrolysis coatings have durable abrasion and corrosion resistance properties. This is believed to be due in particular to the fact that the process involves the deposition of coating material on a heated substrate. Pyrolysis is also generally more economical than alternative coating processes such as sputtering, particularly in terms of investment in the installation.

The substrate is preferably in the form of a band or sheet of glassy material such as glass or any other rigid transparent material. In view of the proportion of incident solar radiation that is absorbed by the glazing panel, especially in environments where the panel is exposed to strong or prolonged solar radiation, there is a heating effect on the panel that may require the substrate to subsequently be subjected. quenching process. However, the durability of the cladding allows the panel to be mounted with the clad face facing outwards, thus reducing the heating effect.

The substrate should preferably be colored glass. Combining a coloration within the material with a coating according to the invention has been found to make it easier to achieve the required low light transmission and high selectivity values. The most preferred colors for glass used for roof, side or rear windows of vehicles are gray and green.

The tin oxide / antimony coating should preferably have a thickness of between 400 nm and 800 nm, most preferably between 450 nm and 700 nm. These thicknesses allow a low total transmitted energy factor (TE) to be obtained while maintaining a sufficient level of light transmission. The thick tin oxide / antimony layers, particularly those with low Sb / Sn molar ratio, can not only provide a glazing panel with the required low light transmission and high selectivity values, but also with the advantageous combination of a low solar factor FS and low emissivity.

It may be useful to prevent interaction between the substrate glass and the tin oxide / antimony coating layer. By way of example, it has been found that in the pyrolytic formation of a tin oxide coating from tin chloride on a soda lime glass substrate, sodium chloride tends to be incorporated within the coating as a result of reaction of the glass with the coating precursor material or its reaction products, and this causes the coating to become cloudy. Therefore, if desired, between the substrate and the tin oxide / antimony coating layer a suitable intermediate coating layer can be positioned to reduce turbidity. Such an intermediate layer is usually unnecessary in the case of low light transmission panels, since turbidity is not visible to a significant degree. If used, it may comprise a silicon oxide with a geometric thickness of for example about 100 nin. The presence of a silicon oxide undercoating on the soda lime glass has the advantage of inhibiting the migration of sodium ions from the glass by diffusion or otherwise into the coating layer. of tin oxide / antimony during the formation of such an upper layer or during subsequent high temperature treatment.

The panels according to the invention are particularly well suited for use as vehicle roof panels, for example tilting or sliding sunroofs, or even to form substantially the entire roof area of ​​vehicles. These panels can also be advantageously used as rear or rear side windows of vehicles.

Glazings with a light transmittance of less than 35% are advantageous for use as vehicle roof panels, particularly if the panel is intended to form most or all of the roof area. Although such a low level of light transmission is required according to the invention, it is also desirable for the glazing panel to transmit some visible light radiation in order to contribute to the natural illumination of the interior of the vehicle.

A high level of coating selectivity in combination with a low level of light transmission allows low transmission of solar energy. The selectivity provided by the invention is essentially at least 1.3 and preferably at least 1.5. A particular advantage of the invention is that in practice

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allows obtaining selectivity values ​​close to 2.

Therefore, the power transmission (TE) should preferably be less than 15%, even more preferably less than 10%. Such a low power transmission value helps reduce the load on vehicle air conditioning systems.

In the case of panels that make up the entire roof, it may be advantageous to use a panel with a light transmittance as low as 10% and a 5% power transmission, giving a selectivity of 2. In the case of sunroofs, a slightly higher transmission is generally preferable, for example a light transmittance of about 20% and a power transmission of about 12%, again resulting in a selectivity of around 2%. .

The molar ratio Sb / Sn in the coating should preferably be in the range 0.07 to 0.20, even more preferably 0.08 to 0.15. Preferred ranges derive from the need for sufficient antimony to be effective in achieving the required low transmission properties, but at the same time not present in amounts capable of affecting optical quality.

It is convenient that the coating comprises only a single layer of tin oxide / antimony. However, it is possible to provide for one or more other coating layers applied by

Pyrolysis or any other coating methods in order to achieve certain desired optical qualities. However, attention is drawn to the fact that when applied by pyrolysis, the tin oxide / antimony layer has sufficient mechanical durability and chemical resistance to adequately serve as the exposed layer. Alternatively, said layer may be applied to the surface of the substrate intended to face an interior of a vehicle.

The panels according to the invention have low visible light reflectivity properties which are particularly advantageous for vehicle glazing. Visible light reflectivity (RL) should preferably be less than 12%, and may typically be between 5 and 12%.

The panels according to the invention may be installed in single or multiple assemblies. The coating layers are applied to the heated substrate by spraying the liquid reagents, for example by means of a spray nozzle. Although lacking the precision of the alternative pyrolytic chemical vapor deposition (CVD) method, liquid spraying is a convenient and economical method for depositing a thick coating layer, as in the present case. Undoubtedly, CVD is not a generally convenient method for forming thick coatings.

Especially in the preferred case of applying the coating to a colored substrate, any variations in coating thickness or uniformity resulting from the use of a spray method are hardly visible. The tin source is preferably SnCl.₂ and the source of antimony is SbCI₂both of these materials being added to the water for the spraying operation. Organometallic material may also be used.

I dissolved.

When it is desired to manufacture pyrolytically coated flat glass it is preferable to do so when the glass has just been formed.

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This has economic advantages because it is not necessary to reheat the glass for pyrolytic reactions to take place, and it also has advantages with regard to the quality of the coating as it is ensured that the glass surface is in the primitive condition. Accordingly, it is preferable that said coating precursor material be brought into contact with an upper face of a heated glass substrate consisting of newly formed flat glass.

Accordingly, the glazing panels according to the invention may be manufactured as follows. The pyrolytic coating step may be carried out at a temperature of at least 400 ° C, ideally between 550 ° C and 750 ° C.

To form each coating, the substrate is contacted within a coating chamber with a droplet spray containing the antimony and tin-containing reagents. The spray is applied by one or more spray nozzles arranged in a manner following a trajectory that promotes coating over the full width of the band to be coated.

In a spray-pyrolysis, the molar ratio Sb / Sn in the finished coating is not directly proportional to the ratio in the reactant mixture, and is usually substantially different from this. The level of antimony incorporation within the coating is significantly affected by parameters such as spray rate, glass type and glass temperature. Therefore, attempts to calculate the coating ratios from the starting ratios are unreliable, and preliminary experiments are necessary to determine which starting ratios are capable of satisfying the necessary coating ratios in each specific case.

After deposition, the coatings are preferably polished using any desired conventional polishing means. If desired, the coated product may also be subjected to a tempering operation.

The invention will hereinafter be described in more detail with reference to the following nonlimiting examples.

In the Examples, the Sb / Sn molar ratio in the coating layers was determined by an X-ray analysis technique in which the number of X-ray counts of the respective elements was compared. Although this technique is not as accurate as one would employ if calibrated by chemical dosing, the similarity of antimony and tin means that they respond similarly to X-rays. Thus, the ratio between the measured number of obese counts of the respective elements provides a good approximation to their molar ratio.

EXAMPLES 1-21

In all examples a mixture of Sb / Sn was applied in an aqueous mixture to a moving band of a heated glass substrate having a thickness of 4 mm. Several different types of glass were employed as shown in Table A below. The initials given in the entries in this table and the following tables (TL, TE, etc.) have the meanings described hereinbefore. Columns FSpl and FSp2 in Table C refer to the solar factor, respectively on the side of the glass facing the light source (position 1) and on the opposite side to the one facing the light source (position 2). Unless otherwise indicated, the properties shown in the tables were measured under the action of Lighting Agent C. Under the conditions described, the difference in TL between the use of Lighting Agent C and Lighting Agent A (commonly used in the field of motor vehicles) was found to be minimal and of the same order as normal measurement errors.

In each case, the mixture was a coating precursor solution containing approximately 1,000 g (total) of SnCl₂ and of SbCl₃per liter of the mixture and in the proportions shown in Table B below. The solution was applied to the substrate by means of an alternative motion animated spray nozzle which followed a trajectory over the entire width of the band.

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Table A

<td>Glass Type</td><td>Colorless</td><td>Green A</td><td>Green C</td><td>Gray</td><td>Gray Avg. 1</td><td>Gray Avg. 2</td>

<td>λρ in transmission</td><td></td><td> 505.4/508,</td><td> 509,7/510,</td><td> 470,1/493,</td><td> 493,2/502,</td><td> 494,6/502,</td>

<td>(nm)</td><td></td><td> 5</td><td> 2</td><td> 9</td><td> 7</td><td> 8</td>

<td>[Agent dc</td><td></td><td></td><td></td><td></td><td></td><td></td>

<td>Lighting: C / A]</td><td></td><td></td><td></td><td></td><td></td><td></td>

<td>Purity (%)</td><td></td><td> 2,9/3.4</td><td> 3,2/4.0</td><td> 1,5/0,8</td><td> 5,6/5,1</td><td> 9,9/9,3</td>

<td>TL (%)</td><td> 89.0</td><td> 72,66/71.1</td><td> 67,36/65.6</td><td> 55,65/55,5</td><td> 36,8/35,8</td><td> 37,07/35,1</td>

<td>[Agent of</td><td></td><td> 2</td><td> 9</td><td> 6</td><td></td><td> 3</td>

<td>Lighting: C / A |</td><td></td><td></td><td></td><td></td><td></td><td></td>

<td>TE (%) (CIE)</td><td> 83.0</td><td> 44.0</td><td> 37,1</td><td> 56.9</td><td> 25,9</td><td> 20,9</td>

<td>TL / TE (CIE C)</td><td> 1.07</td><td> 1,65</td><td> 1.81</td><td>0.9S</td><td> 1.42</td><td> 1,77</td>

<td>FS pi (CIE) (%)</td><td> 86.0</td><td> 56.8</td><td> 51.7</td><td> 66,3</td><td> 43,4</td><td> 39,7</td>

<td>TL / FS</td><td> 1.03</td><td> 1,28</td><td> 1.30</td><td> 0,84</td><td> 0,85</td><td> 0,93</td>

The sprayed tin and antimony components reacted to form a pyrolytic tin oxide coating on the glass. The parameters employed and the results obtained are shown in Tables B and C.

Attention is drawn to the fact that Examples 4 and 5 do not comply with the conditions set forth in the appended claims with respect to the required coating thicknesses and selectivity, and in the case of Example 5 also with respect to the required transmission. bright. These examples are included herein for comparison purposes to show that when operating outside the scope of the claims lower quality results are obtained.

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Table Β

<td>Example</td><td>Kind of</td><td>Sb / Sn</td><td>Sb / Sn</td><td>Thickness</td><td>TL</td><td>RL</td>

<td></td><td>Glass</td><td>From</td><td>of</td><td>of</td><td> (%)</td><td> (%)</td>

<td></td><td></td><td>rctigcntcs</td><td>cladding</td><td>cladding</td><td></td><td></td>

<td></td><td></td><td></td><td> 0</td><td> 0</td><td></td><td></td>

<td></td><td></td><td></td><td></td><td>(nm)</td><td></td><td></td>

<td> 1</td><td>Colorless</td><td> 0,20</td><td> 0.11</td><td> 535</td><td> 23,0</td><td> 10,0</td>

<td> 2</td><td>Colorless</td><td> 0.20</td><td> 0.12</td><td> 470</td><td> 27,0</td><td> 10,0</td>

<td> 3</td><td>Colorless</td><td> 0.30</td><td> 0.14</td><td> 670</td><td> 13,0</td><td> 10,0</td>

<td> 4</td><td>Colorless</td><td> 0.30</td><td> 0.16</td><td> 306</td><td> 27,0</td><td> 11,0</td>

<td> 5</td><td>Colorless</td><td> 0.30</td><td> 0.19</td><td> 119</td><td> 56,0</td><td> 10,0</td>

<td> 6</td><td>Green A</td><td> 0,30</td><td> 0.17</td><td> 670</td><td> 10,4</td><td> 9,9</td>

<td> 7</td><td>Green C</td><td> 0.30</td><td> 0.14</td><td> 670</td><td> 9,6</td><td> 9,9</td>

<td> 8</td><td>Gray Mcd.</td><td> 0.30</td><td> 0.14</td><td> 520</td><td> 6,4</td><td> 10,5</td>

<td></td><td> 2</td><td></td><td></td><td></td><td></td><td></td>

<td> 9</td><td>Gray Mcd.</td><td> 0.30</td><td> 0.14</td><td> 520</td><td> 6,5</td><td> 10,5</td>

<td></td><td> 2</td><td></td><td></td><td></td><td></td><td></td>

<td> 10</td><td>Green A</td><td> 0.20</td><td> 0.1 1</td><td> 530</td><td> 1-5,7</td><td> 10,3</td>

<td> 11</td><td>Green C</td><td> 0,20</td><td> 0,1 1</td><td> 530</td><td> 17,3</td><td> 10,3</td>

<td> 12</td><td>Gray Avg. 1</td><td> 0.20</td><td> 0.11</td><td> 530</td><td> 9,5</td><td> 10,2</td>

<td> 13</td><td>1 Gray Mcd.</td><td> 0.20</td><td>hi 1</td><td> 530</td><td> 9,6</td><td> 10,2</td>

<td></td><td> 2</td><td></td><td></td><td></td><td></td><td></td>

<td> 14</td><td>Gray</td><td> 0.175</td><td>l oj l</td><td> 640</td><td> 15,0</td><td> 10,0</td>

<td> 15</td><td>Gray</td><td> 0.175</td><td> 0,1 1</td><td> 530</td><td> 19,0</td><td> 10,0</td>

<td> 16</td><td>Green A</td><td> 0,175</td><td> 0,11</td><td> 640</td><td> 19,0</td><td> 10,0</td>

<td> 17</td><td>Green A</td><td> 0,175</td><td> 0,11</td><td> 530</td><td> 25,0</td><td> 10,0</td>

<td> 18</td><td>Green C</td><td> 0,175</td><td> 0,11</td><td> 640</td><td> 17,8</td><td> 10,0</td>

<td> 19</td><td>Green C</td><td> 0,175</td><td> 0,11</td><td> 530</td><td> 23,0</td><td> 10,0</td>

<td> 20</td><td>Gray Mcd.</td><td> 0,175</td><td>hi 1</td><td> 640</td><td> 10,0</td><td> 10,0</td>

<td> 21</td><td>I Gray Mcd.</td><td> 0,175</td><td> 0.1 1</td><td> 530</td><td> 12,6</td><td> 10,0</td>

Table C

<td>Example</td><td>YOU</td><td>RE</td><td>FS pl</td><td>FS p2</td><td>Einissividadc</td><td>TL / TE</td><td>TL / FS</td>

<td></td><td> (%)</td><td> (%)</td><td> (./»)</td><td> (%)</td><td> (&gt;»</td><td></td><td></td>

<td> 1</td><td> 17,0</td><td>H, 0</td><td> 35,0</td><td> 31,0</td><td> 0,35</td><td> 1.35</td><td> 0,66</td>

<td> 2</td><td> 21,0</td><td> 11,0</td><td> 38,0</td><td> 39.0</td><td></td><td> 1,29</td><td> 0,71</td>

<td> 3</td><td> 10,0</td><td> 11,0</td><td> 30,0</td><td> 26,0</td><td></td><td> 1,30</td><td> 0,43</td>

<td> 4</td><td> 25,0</td><td> 13,0</td><td> 41,0</td><td> 42.0</td><td> 0,53</td><td> 1,08</td><td> 0,66</td>

<td> 5</td><td> 51,0</td><td> 13,0</td><td> 60.0</td><td> 61,0</td><td> 0,76</td><td> 1,14</td><td> 0,97</td>

<td> 6</td><td> 5,8</td><td> 10,9</td><td> 26,8</td><td> 22,9</td><td> 0,35</td><td> 1,80</td><td> 0,39</td>

<td> 7</td><td> 5,1</td><td> 10,9</td><td> 26.3</td><td> 22,3</td><td> 0,35</td><td> 1,90</td><td> 0,36</td>

<td> 8</td><td> 4,2</td><td> 10,9</td><td> 25.6</td><td> 22.0</td><td> 0,40</td><td> 1,52</td><td> 0,25</td>

<td> 9</td><td> 3,5</td><td> 10,9</td><td> 25.1</td><td> 21.5</td><td> 0,40</td><td> 1,86</td><td> 0,26</td>

<td> 10</td><td> 10,0</td><td>H, l</td><td> 29,9</td><td> 25.8</td><td> 0.35</td><td> 1,87</td><td> 0,62</td>

<td> 11</td><td> 8,7</td><td> 11,1</td><td> 28,9</td><td> 24.8</td><td> 0,35</td><td> 1,99</td><td> 0,60</td>

<td> 12</td><td> 5,5</td><td>1 l, the</td><td> 26,6</td><td> 22,3</td><td> 0,35</td><td> 1,73</td><td> 0,36</td>

<td> 13</td><td> 4,8</td><td> 1 1,0</td><td> 26.0</td><td> 21.7</td><td> 0,35</td><td> 2,00</td><td> 0,37</td>

<td> 14</td><td> 10,0</td><td> 1 1,0</td><td> 30.0</td><td></td><td></td><td> 1,50</td><td> 0,50</td>

<td> 15</td><td> 14,0</td><td> 1 1,0</td><td> 33,0</td><td> 1</td><td></td><td> 1,36</td><td> 0,58</td>

<td> 16</td><td> 9,8</td><td> 11,0</td><td> 29.8</td><td></td><td></td><td> 1,94</td><td> 0,64</td>

<td> 17</td><td> 13,0</td><td> 11,0</td><td> 32,0</td><td></td><td></td><td> 1,92</td><td> 0,78</td>

<td> 18</td><td> 8,6</td><td> 11,0</td><td> 28,9</td><td></td><td></td><td> 2,07</td><td> 0,62</td>

<td> 19</td><td>ll the</td><td> 11,&lt;&gt;</td><td> 31.0</td><td> 2,09</td><td> 0,74</td>

<td> 20</td><td> 5,4</td><td> 11,0</td><td> 26.5</td><td> 1,85</td><td> 0,38</td>

<td> 21</td><td> 7,7</td><td> 11.0</td><td> 27.7</td><td> 1,77</td><td> 0,45</td>

As variants of Examples 14 and 20 coatings having a thickness of 730 nm and an Sb / Sn ratio of 010 were obtained. In both cases the resulting properties were substantially the same as in the original Examples 14 and 20.

In all examples, the product coated substrate was blue in transmission with a dominant wavelength (λ [&gt;) of between 470 and 490 nm and a turbidity factor of between 0.7 and 1.1.

Lisbon, June 5, 1996

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VICTOR CORDON STREET, 10 - A 3 '

1200 USBOA