Self-cleaning lighting device

The present invention relates to the types of luminaires that are exposed to air pollution, especially organic pollution.

European Patent No. 0887104 states that TiO on translucent protective covers for luminaires.₂The general principles of coating are described. TiO₂Shows photocatalytic activity, i.e. the ability to catalyze radical oxidation reactions under UV radiation, especially when crystallized in the anatase form. Hydrocarbon residues, such as those derived from automobile exhaust, can thus be broken down into smaller particles that are less adherent and less fatty than the original hydrocarbons.

In addition, TiO₂Has hydrophilicity. TiO₂Once attached, the water is in the form of a membrane that can optimally distribute and dissolve the decomposition products described above and then remove them by hydrodynamic effects.

Thus, for example, as is known from European Patent No. 850204, in order to produce a self-cleaning effect, TiO₂There is a synergistic effect between radical oxidation catalysis and hydrophilicity, which is exactly the key when the substrate to be applied is glass, because the best optical transparency is thus permanently maintained. Because it is done.

European Patent No. 887104 describes a wide range of TiOs.₂Mentions the preparation process. It refers in more detail to the conventional strengthening treatment of flat glass with a titanium alkoxide solution, heat treatment at 650-800 ° C for 30 seconds to 5 minutes.

The purpose of such a process is to crystallize primarily anatase-type TiO for application to translucent covers for tunnel lamp protection.₂Is to manufacture.

<p> The inventors have also studied applications in this field, the effectiveness of self-cleaning coatings on tunnel lamps depends in particular on their location within the tunnel (distance from the end of the tunnel), and especially the light source is the UVA component (315 ~ I noticed that it depends on the type of light source due to the fact that it may or may not have a wavelength of 400 nm). Anatase crystallized TiO₂It is basically these wavelengths that can activate.</p><p> Near one end of the tunnel, the amount of residual UVA is photocatalytically TiO₂Can be sufficient to activate. In addition, the illumination source of the lamp itself may have a UVA component, TiO₂Some of which is sufficient to rejuvenate can be transmitted through the translucent cover as long as its surface is in contact with the atmosphere of the tunnel. This is the case for fluorescent type lamps.</p><p> However, if the distance from both ends of the tunnel is long, and if the light emitted by the lamp has little or no UVA component, for example in the case of a sodium lamp, TiO₂The above process of producing a product having a photocatalytic activity high enough to observe a desirable and useful self-cleaning effect, unless certain operating conditions not revealed in this production process allow. Do not produce.</p>

<p> To solve this problem, the object of the present invention is a lighting device including a light source and a wall through which at least a part of the radiation emitted by the light source passes, and at least one of two surfaces of the wall. An illuminator in which a photocatalytically active layer is coated on a part thereof, and under the minimum illumination condition, the photocatalytic activity of the layer decomposes organic stains and does not adhere to the layer, and then easily. A luminaire characterized in that it is high enough to make removable particles and / or impart hydrophilicity to the layer.</p><p> The expression "minimum illumination condition" here means that the photocatalytically active layer does not receive UVA from the outside atmosphere of the illuminator or from a light source that has little or no UVA component.</p><p> Therefore, the inventors have aerodynamically affected (very little ventilation) or even under low light at wavelengths other than UVA, such as visible light or UVB, with fatty and adhesive hydrocarbon vapors. A lamp provided with a layer with high photocatalytic activity that has the property of decomposing into fine non-adhesive dust particles that can be removed by a hydrodynamic effect (splash of liquid), especially on the surface that comes into contact with the surrounding atmosphere. Made.</p><p> This very high photocatalytic activity is also evident in its significant hydrophilicity. This property, also referred to as wettability, found in the context of describing the present invention, derives from the radical decomposition of the dirt present on the lamp, where the dirt present is low fat and is not coated by the active layer. It is also the result of the fact that it consists of products.</p><p> The walls of the lighting system take any standard form, but depending on the material and the manufacturing process used, they may be substantially flat, have large or small bends, or even have sharp corners.</p><p> The most well-known photocatalyst TiO according to the lowest photocatalytic activity criteria₂Far beyond what is indicated by layers, the layers according to the invention are TiO₂The photocatalytic activity is 50 W / m at a wavelength centered on 365 nm.²TiO determined by cloudiness measurement under power radiation₂The rate of disappearance of palmitic acid adhering to the layer, expressed in terms of the amount of^-1 Μg^-1·cm²Is.</p><p> In the first main embodiment of the present invention, the coated wall of the luminaire is essentially made of glass, in particular an area of 50 x 50 mm is broken into at least 40 pieces (of tempered glass for automobiles). Standard R43), especially made of tempered glass that breaks into over 60 debris. This selection maximizes the transmission of emitted light and guarantees public safety in the unlikely event that the glass breaks. This safety aspect is spoiled by the glass breaking into a small number of debris, and as it is known, the sharper edges of those debris.</p><p> In this first embodiment, the problem of moving alkali metals (particularly sodium) through the glass to its surface, which is likely to occur, for example when heated by a light source, must be considered. As treated in European Patent No. 850204, alkali metals are TiO₂Affects the photocatalytic activity of the coating. The first means to improve this is, according to the present invention, the total content of the alkali metal oxide and the alkaline earth metal oxide of the glass wall in at least one region of the surface facing the photocatalytic active layer. Does not exceed 15% by weight, and the sodium oxide content does not exceed 10% by weight.</p><p> As described in International Publication No. 94/07806 and International Publication No. 94/07807, the dealkalised soda lime silicate glass is subjected to various technologies, especially electrical technologies such as corona discharge. Obtained by the processing used.</p><p> In the second main embodiment of the present invention, the wall is basically made of clear plastic or several kinds of combined plastics. Suitable such plastics include, for example, polycarbonate, polymethylmethacrylate, polypropylene, polyurethane, polyvinylbutyral, polyethylene terephthalate, polybutylene terephthalate, ionomer resins, such as ethylene / (meth) acrylic acid copolymers neutralized with polyamines. , Cycloolefin copolymers, such as ethylene / norbornene or ethylene / cyclopentadiene copolymers, polycarbonate / polyester copolymers, ethylene / vinyl acetate copolymers, and similar copolymers, which may themselves be blends.</p><p> Of course, the fabrication temperature of the photocatalyst layer at about 650 ° C or higher is incompatible with the adhesion on these plastics. Conversely, the highly active layers according to the invention can be produced, for example, at milder temperatures not exceeding 250 ° C, or even at ambient temperatures. Therefore, it is possible to coat the plastic with it without any effect on the plastic.</p><p> In each of the two main embodiments described above, it is particularly advantageous to insert a silicon-based layer between the wall and the photocatalytically active layer. This intermediate layer is: -If the wall is made of glass, it is a barrier layer that prevents the diffusion of alkali metal from the glass and constitutes a second solution to the above problem, i.e. supported by a bath of molten tin. Silica and derivatives such as silicon oxycarbide or silicon nitride produced by thermal CVD on the strip of float glass, by vacuum techniques such as magnetron sputtering, or by the sol-gel method, ie x is less than 2. SiO_xAn intermediate layer made of, and: If the wall is made of plastic, a scratch resistant layer that is essential in this case: plasma chemical vapor deposition (PE-CVD), electron beam deposition, magnetron sputtering, It is a SiOCH (N) intermediate layer by ion-enhanced CVD, ion beam CVD, etc.</p><p> As is known, the stain resistance effect correlates with the thickness of the active layer of a given photocatalytically active composition, so this thickness is preferably between 100 and 1000 nm, TiO.₂The surface density of the layers is 1 and 100 μg / cm²Between 2 and 65 μg / cm²Between.</p><p> In order to fully benefit from the synergistic effect of the ability to catalyze radical oxidation reactions and hydrophilicity, the luminaire according to the invention preferably includes means of spraying a liquid onto the active layer, for example. It is already installed in the headlights of some automobiles without the photocatalyst layer.</p><p> Preferably, the translucent wall of the luminaire is coated with a photocatalytic active layer, at least on the surface opposite to the light source. The most important thing (air pollution) intended to be resolved preferentially in the background context of the present invention is the problem of pollution of the outer surface of the luminaire.</p><p> However, if the light source is protected in an unsealed enclosure, the surface of the wall facing the light source may be susceptible to certain organic pollutants. Therefore, coating the surface with a photocatalytically active layer is not excluded. In this case, the ratio of radiation from the light source capable of activating the layer is much higher than that of the opposite layer, and a relatively large ratio of radiation does not penetrate the wall.</p><p> Excellent results, especially TiO₂Fe, Nb, Ta, Pt, Rh, Ag, Pd, Sn, Cd, W, Ce, Zr, Cu, Ru, Mo, Al, Bi, V, Co and / or Ni, optionally doped with their oxides and / or salts, and fully mixed or mixed with it.₂It is obtained in an active layer comprising.</p><p> Doping increases the photocatalytic effect of titanium oxide by increasing the absorption band and / or the number of charge carriers and / or the efficiency and reaction rate of the photocatalytic reaction.</p><p> The dopant may consist of small particles that are inserted between the titanium oxide microcrystals that are aggregated into nanoparticles, that is, incorporated therein.₂It may be small particles distributed on the outer surface of the nanoparticles, or it may be a thin layer coated with a photocatalytically active layer.</p><p> The object of the present invention is also a method for manufacturing the above-mentioned lighting apparatus, in which the photocatalytically active layer is subjected to a solgel method, chemical vapor deposition (CVD) or atmospheric pressure plasma chemical vapor deposition (APPECVD), or It is formed under vacuum or reduced pressure, especially by magnetic field cathode sputtering (or magnetron sputtering).</p><p> The sol-gel method is particularly suitable for adhesion on walls of complex shapes.</p><p> According to one preferred method of producing a layer of high photocatalytic activity, this is: at least one precursor of an essentially inorganic substance and at least one of the essential inorganic substances that make up the mesoporous structure of the layer: Preparation of a liquid composition comprising one organic structural agent, -precursor precipitation and molecular growth obtained from the precursor around the organic structural agent, -between 0.5 and 100 nm in diameter. Addition of some optionally doped basic microcrystals or nanoparticles of titanium oxide to the liquid composition, -application of the composition to the surface to be coated, and-removal of organic structural agents to titanium oxide. The mesoporous structure by the sol-gel method, which involves incorporating the microcrystals into the mesoporous structure while maintaining its integrity essentially, and allowing some of them to aggregate in it as nanoparticles. Is formed as.</p><p> To maintain the normal strengthening of the glass, it is preferable that the temperature does not exceed 250 ° C when performing this method. Therefore, the step of removing the structural agent can be heating to 250 ° C. for 2 hours or UVA irradiation at an ambient temperature.</p><p> Other objects of the invention include: -glass or plastic-based walls for the above-mentioned luminaires, and-tunnel lighting, public lighting or airport runway lighting, or land, water or air transport. The use of the above luminaires for headrides or signal lights for engines, especially for automobiles, and also for indoor lighting.</p><p> The present invention will be described with reference to the following examples.</p>

A sublayer based on silicon oxycarbide, shown as SiOC (without measuring the actual oxygen and carbon content in the coating), was attached onto the glass, which is still in the form of a strip of float glass. This sublayer was deposited by CVD using a Si precursor, specifically SiH diluted with nitrogen while the glass was still at a temperature of about 550-600 ° C.₄/ Ethylene mixture was used and adhered in the float chamber using a nozzle placed laterally above the float glass strip of the flat glass production line. The resulting coating had a thickness of about 50 nm and a refractive index of about 1.55. The float glass sample provided with the SiOC sublayer of the alkaline barrier thus obtained was cut to the size of the tunnel lamp cover. These samples were washed, rinsed, dried and subjected to 45 minutes of ozone / UV treatment.

For bent / tempered glass, instead of the CVD sublayer of SiOC in the float chamber, SiO by the subsequent sol-gel method on the bent tempered glass in a substantially cold state or at a temperature not exceeding 250 ° C.₂It was possible to maintain the benefits of strengthening using layers.

This layer was actually equivalent to the SiOC layer by CVD in the alkali metal diffusion barrier function.

A coating with a mesoporous structure was formed on the sublayer.

In the first step, 22.3 ml of tetraethoxysilane, 22.1 ml of absolute ethanol, and 9 ml (pH 1.25) of HCl in desalinated water are mixed in a flask until the solution is clear, then the flask is mixed at 60 ° C. A liquid treatment composition was obtained by placing the flask in a water bath for 1 hour.

In the second step, the sol obtained above is mixed with a solution of polyoxyethylene / polyoxypropylene block copolymer (molecular weight 8000) sold by BASF under the brand name of Pluronic PE6800, and the PE6800 / Si molar ratio becomes 0.01. Added in such a ratio. It was obtained by mixing 3.78 g PE6800, 50 ml ethanol and 25 ml sol.

TiO crystallized into anatase type with a size of about 50 nm₂The nanoparticles were added to the liquid composition thus obtained just prior to implantation on the sample. Adhesion was performed by spin coating with an initial volume of 3 ml per sample. (Other equivalent coating techniques include dip coating, spray coating, thin layer coating, roll coating, flow coating, etc.)

The sample was then heated at 250 ° C. for 2 hours.

The pores of the coating thus formed were 4 to 5 nm in size.

The Ti / Si atomic ratio was confirmed by SIMS analysis of the mesoporous coating to be exactly the same as that of the original liquid composition. SIMS analysis also confirmed that the nanoparticles were evenly distributed in the three dimensions of the coating.

The coating thickness t in nm was measured from the SIMS profile and SEM micrographs.

μg / cm²Represented by TiO₂The amount of was measured by fluorescent X-ray.

The photocatalytic activity was measured by the following method. 1. About 15 cm²The test was carried out with the coating of. 2. Weigh the sample, the thickness of the base material, and the light transmittance T_LAnd cloudiness T_d(Both of these are expressed in%). 3. A palmitic acid solution (8 grams of acid per liter of chloroform) was applied onto a vertical substrate by spraying it back and forth 3-4 times in a row at a glass / spray distance of 20 cm. 4. In order to measure the nanometer-based thickness of the adhered palmitic acid, the sample was weighed after the adhered palmitic acid. 5. Light transmittance T after adhesion_LAnd cloudiness T_dWas measured. 6. Approximately 50W / m²The change in haze as a function of irradiation time under UVA of intensity was measured. 7. The time when the cloudiness decreased by 50% was calculated from the graph (this time is T)._1/2Called (disappearance)). And 8. Photocatalytic activity of the coating, v (nm / h) = (palmitic acid thickness (nm)) / (2 × T_1/2It was determined as the disappearance rate v (nm / h) of palmitic acid defined as (disappearance) (h)).

TiO in coating₂The value of photocatalytic activity relative to the amount of was also measured. Finally, the optical properties, i.e. light reflectance R_LAnd cloudiness T_d(%) Was measured.

The Ti / Si ratio was equal to 1.

The following results were obtained. t = 454nm TiO₂= 33.3 μg / cm² v = 620nm / hv / TiO₂= 18nm h^-1 Μg^-1·cm² R_L= 9.7% T_d=0.3%

Two sodium tunnel lamps that do not actually emit UVA, and two fluorescent lamps were equipped with a glass cover treated according to the examples.

Each of the two lamps of the above types was equipped with an untreated float glass cover.

Each type of lamp with treated and untreated glass covers, one in the tunnel entrance area and the other in the central area of the tunnel, which receives virtually no or little UVA from the outside atmosphere, for 84 days. Arranged separately.

When removing the treated glass, care was taken not to expose it to UVA that is not present in the tunnel.

The lamps were not always on, and tunnels were rarely 100% hourly illuminated, averaging 9 hours and 30 minutes per day.

The treated glass was completely wet at the time of installation.

The cover was examined by the following method. -Visual observation of contamination. Area 5 cm²Removal of dust on the surface of the surface with a cloth. This revealed the condition of dirt and made it possible to evaluate the "easy clean" function. -Evaluation of hydrophilicity by adhering a few drops of deionized water to the glass surface.

The results are shown in the table below.

<tables num="1"><img file="JP2007523740A_D0001.tif" /></tables>

<tables num="2"><img file="JP2007523740A_D0002.tif" /></tables>

The difference in behavior in the entrance region can be explained by the following. Enter the tunnel and TiO₂There is UVA that makes the layer more effective, and there is less contamination confinement than in the central region.

In the central region, glass contamination was also seen in the treated glass, and hydrophilicity was maintained in the case of the treated glass. However, in the case of treated luminaires containing fluorescent lamps (UVA radiation, thus layer activation), the contamination is present in the form of dry stains that can be very easily removed from the surface. Highly adherent fatty contamination was observed on the untreated glass.

Therefore, the inventors have provided a lamp that remains clean and / or is easy to clean under low light and maximum pollution conditions.