SE513945C2 - Glazing panel with sun-filtering properties - Google Patents

Abstract

A glazing panel comprises a vitreous substrate carrying a pyrolytically formed tin/antimony oxide coating layer containing tin and antimony in a Sb/Sn molar ratio of from 0.01 to 0.5. The coated substrate has a solar factor FS of less than 70%. The panel is formed by chemical vapour deposition from a reactant mixture comprising a source of tin and a source of antimony.

Description

15 20 25 30 513 945 2 The "light transmittance" (TL) is the light fl that passes through a substrate as a percentage of the incident light..

“Light reflectance” (RL) refers to the light beam that is reflected from a substrate as a percentage of the incident light beam.

The total “energy transmission” (TE) is the total radiated energy directly transmitted through a substrate as a percentage of the incident radiant energy.

The "energy response" (RE) is the radiant energy that is reflected from a substrate as a percentage of the incident radiant energy.

The "solar factor" (FS) is the ratio between the sum of the total energy directly transmitted through a substrate (TE) and the energy absorbed and re-radiated from the side facing away from the radiation source (AE) as part of the total radiant energy incident on the substrate.

The “selectivity” of the coated substrate refers to the difference between the light transmission and the energy transmission. In the case of building glass, it is often referred to as the ratio of light transmission to solar factor (TL / F S), but for vehicle glass it is usually referred to as the ratio of light transmission to energy transmission (TL / T E).

The “dominant wavelength” (XD) is the wavelength peak in the range transmitted or reflected by the coated substrate.

The "purity" (p) of the color of the substrate refers to the excitation purity measured by light source C.

It is specified according to a linear scale on which a white light source has a purity of zero and the pure color has a purity of 100%. The purity of the coated substrate is measured from the side opposite the coated side. 10 15 20 25 30 513 945 3 “Emissivity” (s) is the ratio of energy emitted from a given surface at a given temperature to that of a perfect radiator (black body with an emissivity of 1.0) at the same temperature.

From a technical point of view, it is desirable that the glass in sunny conditions should not allow too much of the total incident solar radiation to pass so that the vehicle or building is not overheated. The transmission of total incident solar radiation can be expressed in terms of “solar factor” (the fi nied above). In the case of vehicles, the main energy factor to be taken into account is the total directly transmitted energy (TE), since the energy that is absorbed intimately and that is radiated (AE) is diverted through the movement of the vehicle.

Our earlier English patent GB 2 200 139 describes and its patent claims comprise a process for forming a pyrolytic tin oxide coating on a hot glass substrate by spraying a solution containing a tin compound and additives which produce in the coating both fl uor and such materials as antimony , arsenic, vanadium, cobalt, zinc, cadmium, molybdenum, tellurium and manganese to give the coating a low emissivity and a low specific internal diuretic factor. Although the resulting coating exhibits many desirable properties, it does not achieve it in combination with properties that are now sought after for vehicle window glass with solar resistance.

It is an object of the present invention to provide a glazing panel which exhibits a high level with respect to soltering properties in combination with other desirable properties with respect to light transmission and high selectivity.

We have discovered that this and other useful objects can be achieved by means of a whitish substrate which carries a thick pyrolytic spray coating comprising tin and antimony oxides in a specific relative ratio. Thus, the present invention relates to a glazing panel comprising a whitish substrate carrying a spray-formed pyrolytic tin / antimony oxide coating layer in an Sb / Sn molar ratio of from 0.05 to 0.5, wherein the coated substrate has a light transmission (TL) of less than 35% and a selectivity (TL / TE) of at least 1.3.

A number of techniques are known for finding coatings on a whitish substrate including pyrolysis and cathode understanding. Pyrolysis usually has the advantage of producing a hard coating, which eliminates the need for a protective layer. Coatings formed by pyrolysis have durable abrasion and corrosion resistance properties. It is believed that this is due in particular to the fact that the process involves depositing the coating material on a hot substrate. Pyrolysis is also generally cheaper than alternative coating processes such as sputtering, especially in terms of factory investments.

The substrate is preferably in the form of strips or sheets of vitreous material, such as glass or some other transparent rigid material. Given the proportion of incident solar radiation absorbed by the glazing panel, especially in environments where the panel is exposed to strong or long-term solar radiation, there is a heating effect on the panel that may require the substrate to be subjected to a curing process. However, the durability of the coating allows the panel to be easily mounted with the coated surface outermost, thereby reducing the heating effect.

The substrate is preferably formed of colored glass. It has been found that the combination of coloring of the material in the glass and a coating according to the invention facilitates the achievement of the desired low light transmission and high selectivity. The usually preferred colors for glass used in vehicle roofs, sides or rear windows are gray or green. 513 9455 The tin / antimony oxide coating preferably has a thickness of from 400 to 800 nm, most preferably 450-700 nm. Such thicknesses allow the achievement of a low total transmitted energy factor (TE) and at the same time the achievement of a sufficient level of light transmission. Thick layers of tin / antimony oxide, especially layers having a low Sb / Sn molar ratio, can not only provide a glazing panel with the necessary low light transmission and high selectivity but also with the advantageous combination of low solar factor FS and low emissivity.

It may be useful to prevent interaction between the glass of the substrate and the tin / antimony oxide coating layer. For example, it has been found that in the pyrolytic formation of a tin oxide coating from tin chloride on a soda glass substrate, sodium chloride has a tendency to be incorporated into the coating as a result of reaction of the glass with the coating precursor material or its reaction products. leads to light diffusion in the coating. Thus, it may be desirable to place an intermediate layer between the substrate and the tin / antimony oxide coating. Such an intermediate layer is usually not necessary for panels having a low light transmission, since the diffusion can not be noted to any significant extent. If used, it may comprise a silica having a geometric thickness, for example about 100 nm. The presence of silicon oxide intermediate coating on soda glass has the advantage that it prevents the migration of sodium ions from the glass both by diffusion or otherwise into the tin / antimony oxide coating layer both during the formation of the upper layer or during a subsequent high temperature treatment.

Panels according to the invention are particularly suitable for use as roof panels on vehicles, for example for folding or sliding sunroofs, or possibly to cover substantially the entire roof area of the vehicle. They can also be used to advantage in the vehicle's rear or rear side windows.

Glazing with a light transmittance of less than 35% is advantageous when used as a vehicle roof panel, especially if it constitutes the greater part or the entire roof area. While such a low level of light transmission is required according to the invention, it is also desirable that the glazing panel should transmit any visible light to provide a contribution to the natural lighting in the interior of the vehicle.

A high level of selectivity of the coating in combination with a low level of light transmissions allows a low solar energy transmission. The selectivity provided by the invention is substantially at least 1.3 and preferably at least 1.5. It is a particular advantage of the invention that in practice it allows the attainment of selectivity values close to 2.

The energy transmission (TE) is therefore preferably less than 15%, most preferably less than 10%. Such low energy transmission values help to reduce the load on the vehicle's air conditioning system.

With a full roof panel, it may be advantageous to use a panel with a light transmittance as low as 10% and an energy transmission of exactly 5%, which gives a selectivity of 2. For an openable roof panel, a slightly higher transmission is preferred, e.g. light transmission of about 20% and an energy transmission of about 12%, which again gives a selective activity approaching 2.

The Sb / Sn molar ratio of the coating is preferably in the range 0.07-0.20, most preferably 0.08-0, 15. The preferred ranges arise from the need to have a sufficient amount of antimony to effectively provide the necessary low the transmission characteristics but * still not be present in sufficient quantities to affect the optical quality ÉCÉCII.

Preferably, the coating comprises a single layer of tin / antimony oxide. However, it is possible to provide one or more additional coating layers, either applied by pyrolysis or by other coating methods, in order to achieve certain particularly desired optical properties. It should be noted, however, that the tin / antimony oxide layer when applied by pyrolysis exhibits sufficient mechanical durability and chemical resistance to function appropriately as the exposed layer. Alternatively, said layer may be applied to the surface of the substrate which is to face the interior of the vehicle.

The panels according to the invention have a low reactivity for visible light, which is especially advantageous in vehicle glass. It is preferred that the reflectivity of visible light (RL) is lower than 12% and may preferably be between 5 and 12%.

The panels according to the invention can be installed in single or glazing units.

The coating layers are applied to the hot substrate by spraying the reactants in a liquid state, for example using a spray nozzle. Although liquid spraying lacks the precision of the alternative pyrolytic method, CVD technology, it is a convenient and inexpensive method for depositing a thick coating layer, as in the present case. In fact, CVD technology is usually not a suitable method for forming thick coatings.

Especially in the preferred situation of applying the coating to a colored substrate, any variations due to the use of a spray method in thickness or evenness of the coating are hardly visible. It is preferred that the tin source is SnCl 2 and the antimony source is SbCl 3, both materials being added to water in the spray process. Dissolved organometallic materials can also be used.

When it is desirable to produce pyrolytically coated flat glass, it is best to do so when the glass is newly formed. Driving in this way has the economic advantage that there is no need to reheat the glass in order for the pyrolytic reaction to take place and it is also of benefit to the quality of the coating as it ensures that the surface of the glass is in an original condition. Said coating precursor material is therefore preferably brought into contact with an upper surface of a hot glass substrate consisting of a newly formed flat glass. 10 15 20 25 30 513 945 8 Thus, the glazing panels according to the invention can be manufactured as follows. The pyrolytic coating step can be performed at a temperature of at least 400 ° C, ideally from 550 to 750 ° C.

To form each coating, the substrate is contacted with, in a coating chamber, a spray of droplets containing the antimony and tin-containing reactants. The spray is applied by means of one or two spray nozzles arranged to follow a path which allows coating across the strip to be coated.

In a spray pyrolysis method, the Sb / Sn molar ratio in the final coating does not become directly proportional to the ratio in the reaction mixture, and in fact it is usually substantially different from it. The level of antimony incorporation into the coating is significantly affected by such parameters as the spray rate, the type of glass and the glass transition temperature. Attempts to calculate the coating proportions from the starting proportions are therefore unreliable and they are usually necessary to perform preliminary experiments to determine the starting proportions in order to achieve the required coating proportions in a specific case.

When the coatings are deposited, they are preferably polished, using any desired conventional polishing agent. The coated product can also be subjected to tempering if desired.

The invention will now be described in more detail with reference to the non-limiting examples below.

In the examples, the Sb / Sn molar ratio in the coating target was determined by means of X-ray analysis technique in which the number of X-ray pulses from resp. element was compared. Although this technique is not quite as accurate as one if a calibration was made by chemical dosing, the similarity between antimony and tin means that they react in a similar way with respect to X-rays. The ratio of the measured number observed to the width of the band. 513 9459 impulses for resp. elements thus provide a close approximation to their molar ratios.

EXAMPLES 1-21 In all examples, an Sb / Sn mixture in an aqueous mixture was applied to a moving belt of hot glass substrate 4 mm thick. Several types of glass were used, as shown in Table 4 below. The abbreviation designations in this and the other following tables (TL, TE, etc.) have the meaning described above. The columns FS p1 and FS p2 in Table C refer to the solar factor at the side of the glass facing the light source (position 1) and the side facing away from the light source (position 2). Unless otherwise indicated, the properties shown in the tables were measured using illumination source C. Under the conditions described, the difference in TL between the use of illumination source C and the illumination source A (which is more commonly used in the field of motor vehicles) was minimal, ie by the same order of magnitude as routine errors in measurements.

In all cases, the mixture consisted of a coating precursor solution containing approximately 1,000 g (total) of SnCl 2 and SbCl 2 per liter of the mixture and in the proportions shown in Table B below. The solution was applied to the substrate through a spray nozzle which moved back and forth and followed one across the surface. 10 513 945 w Table A;, D i trans- 505.4 / 509.7 / 470.1 / 493.2 / 494.6 / mission (m) 508.5 510.2 493.9 502.7 502, 8 [Ljuskäuæ c / A] 116111161 (%) 2.9 / 3.4 3.2 / 4.0 ii 1.5 / 0.8 5.6 / 5.1 9.9 / 9.3 TL (% ) 89.0 72.66 / 71.12 67.36 / 65.69 55.65 / 55.56 36.8 / 35.8 37.07 / 35.13 [LjuskällazC / A] TE (%) (C113 ) 83.0 44.0 37.1 56.9 25.9 20.9 TL / "rE (CIE C) 1.07 1.65 1.81 0.98 1.42 1.77 Fsp1 (cIE) ( %) 86.0 56.8 51.7 66.3 43.4 39.7 rL / Fs 1.03 1.28 1.30 0.84 0.85 _ 0.93 The sprayed tin and antimony components reacted with a pyrolytic tin oxide coating was formed on the glass, the parameters used and the results obtained are shown in Tables B and C.

It can be noted that Examples 4 and 5 do not fall within the scope of the claims below with respect to the necessary coating thickness and selectivity and in the case of Example 5 also with respect to the required light transmission. These examples are included as a comparison to show that when parameters are selected outside the scope of the requirement, substandard results are obtained. _, 11 :. 'Table B 1 2 Clear 0.20 0.12 470 27.0 10.0 3 Clear 0.30 0.14 670 13.0 10.0 4 Clear 0.30 0.16 306 27.0 11.0 5 Clear 0.30 0.19 119 56.0 10.0 6 Green A 0.30 0.17 670 10.4 9.9 7 Green C 0.30 0.14 670 9.6 9.9 513 945 11 Table B cont. 014 014 011 011 011 011 011 011 011 011 011 011 011 011 r-øn-Iv- fl r- flfi- Ir- fl v-ßx- fl r- fl a-lwoo wb fifl ßklc-àbåNr-IO NN r-IO Table C CO OOOOOOO -Ä- Ä Q LIILIIUIIJIGÖkIIL / IQU) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 515 94512 Table C cont. 19 11.0 11.0 31, o 2.09 0.74 20 5.4 11.0 26.5 1.85 0.38 21 7.7 11.0 27.7 1.77 0.45 As variations in Examples 13 and 20, coatings having a thickness of 730 nm and an Sb / Sn dry ratio of 0.10 were obtained. In both cases, the resulting properties were essentially the same as in the original examples 14 and 20. The coated substrate product in all examples showed a blue tint during transmission, with a dominant wavelength (KD) between 470 and 490 nm and a diodes value between 0.7 and 1 1.

Claims (13)

Patent No. 515,945 Glazing panel comprising a whitish substrate carrying a spray-formed pyrolytic tin / antimony oxide coating layer characterized in that said coating layer has a thickness of at least 400 mn and contains tin and antimony in an Sb / Sn molar ratio of from 0.05 to 0.5, wherein the coated substrate has a light transmittance (TL) of less than 35% and a selectivity (TL / TE) of at least 1.3. Glazing panel according to claim 1, characterized in that the vitreous substrate is made of colored glass. Glazing panel according to Claim 1 or 2, characterized in that the tin / antimony oxide coating has a thickness of from 400 to 800 mn. Glazing panel according to one of the preceding claims, in which the tin / antimony oxide coating has a thickness of fi from 450 to 700 mn. Glazing panel according to one of the preceding claims, characterized in that the coated substrate has a selectivity of at least 1.5. Glazing panel according to one of the preceding claims, characterized in that the coated substrate has an energy transmission factor (TE) of less than 15%. Glazing panel according to claim 6, characterized in that the coated substrate has an energy transmission (TE) of less than 10%. Glazing panel according to one of the preceding claims, characterized in that the Sb / Sn - molar ratio is in the range from 0.07 to 0.20. 513 945 'q 9602268-6 1998-09-16 Glazing panel according to claim 8, characterized in that the Sb / Sn molar ratio is in the range from 0.08 to 0.15. Glazing panel according to one of the preceding claims, characterized in that the temi / antimony oxide coating consists of a single layer. Glazing panel according to any one of the preceding claims, characterized in that said tin / antimony oxide coating constitutes an exposed coating layer. Glazing panel according to one of the preceding claims, characterized in that the reactivity for visible light (RL) is lower than 12%. Use of a glazing panel according to any one of the preceding claims as a roof panel for a vehicle.