WO2016204636A1

WO2016204636A1 - A method for producing a reflective photoluminescent coating, and the reflective photoluminescent powder paint

Info

Publication number: WO2016204636A1
Application number: PCT/PL2016/000062
Authority: WO
Inventors: Witold OSMAŃSKI
Original assignee: GRZESIAK, Maurycy Jacek
Priority date: 2015-06-16
Filing date: 2016-06-10
Publication date: 2016-12-22
Also published as: EP3371259A1; PL412732A1

Abstract

A method for producing a reflective photoluminescent coating using a reflective photoluminescent powder paint made from polyester, polyurethane, epoxy or mixed resin, an adhesion promoter, additives, phosphor, reflective glass beads and an additional phosphor that gives color to the coating, comprises the stages of electrostatic spraying the dry powder paint to a substrate and annealing at a predetermined temperature. The coating in daylight has a color of the pigment added, while at night gives off the color of phosphorescent phosphor. Reflective glass beads increase the reflectivity of the coating, allowing to obtain additional reflective-luminescent effect. Electrostatic increasing of the phosphor particles density near the substrate allows a significant increase in the value of re-emission, and thereby increases the luminance of light-emitting surface.

Description

A method for producing a reflective photoluminescent coating, and the reflective photoluminescent powder paint

The present invention relates to a method for manufacturing a reflective photoluminescent coating of any color and long phosphorescence time. The invention also relates to durable and resilient coating, which during the day has the phosphor's natural color, while at night glows with phosphorescence color of the phosphor (green-yellow, blue-green, blue, purple, yellow, white or other).

The invention includes preparing a composition for making a reflective photoluminescence powder coating giving effects of luminescence and glare, in a formula of a dry binder mixed with the phosphor and suitably-sized glass reflective beads, and with the additives improving the coating properties. Thanks to the increased value of phosphorescence re- emission in relation to the absorbed light, a sustained, long and strong glow has been obtained.

The invention also presents a method of applying a reflective photoluminescent coating on the steel or aluminum sheets, profiles of varying shapes, or plastic components. In the process according to the invention known methods have been used: a high voltage electrostatic spray of 40-100 kV, or an electrokinetic spray using a triboelectrization phenomenon.

The invention is applicable for vertical signs on roads, bridges and other road facilities, on protective barriers, elements of architecture, and the like. The layer of paint retains its color in daylight, but due to the phosphorescence effect invisible in high insolation, a significant reduction in polarization of the reflected light and reduction of blinding white glow is achieved. Glare reduction significantly improves safety.

Luminance characteristics of photoluminescent powder coating achieved according to the invention is many times better than what can be achieved currently in the prior art. The proposed reflective photoluminescent coating is designed primarily for application on the plates, sheets, closed and open profiles made from raw materials such as steel, aluminum, plastics, ceramics, glass, as well as cloth or wood-based materials. Photoiuminescent products made of luminescent material comprising a binder with various additives, as well as methods for their preparation are known in the art.

European patent application EP1708825 A1 discloses a method of manufacturing a photoiuminescent non-slip element, wherein a phosphor, a binder and a non-slip component are applied. A feeding device for coating material is also disclosed.

US patent US7713590 B2 describes a method for applying a base coat of powder paint, which is heated to a temperature of 200-400 °C and which is coated with a further layer of luminescent powder, without cooling a substrate. The operator changes the value of the electrostatic charge, the two layers are heated again to a temperature of 200-450 °C, a transparent powder coating is then applied, and the coated substrate is heated again. The method of preparing the powder consists of heating the binder to the softening temperature and adding the phosphor in a mixing procedure in the molten state. Extrusion in an extruder is followed by pulverization, grinding, classification and sieving of the obtained powder paint.

International patent application WO2009133974 A1 discloses a method for preparing a luminescent powder coating, comprising; mixing a resin, phosphor, pigment and additives, extruding the mixture in a molten state, pulverizing, and removing a portion of the powder having the particle size smaller than the minimum size of the phosphor particles.

From another international patent application WO2009079720 A1 a photoiuminescent coating mixture is known, made on the basis of a liquid resin or a paste, and applied with the methods known from the prior art on helmets,_, clothing, footwear, headgear and other accessories.

According to the disclosure made in the international patent application WO2001088045 A2 a powder paint is used for electrostatic high voltage spraying. The paint has been obtained by mixing a phosphor with a transparent dry powder carrier. Alternatively, the phosphor layer is applied in a wet process on a wet layer of lacquer, and then the coated object is annealed.

The next international patent application WO2013173451 A2 proposes a photoiuminescent composition. The material of the phosphor is mixed with a two- component epoxy resin, and the resultant binder is applied to the surface. US patent application US20030227002 A1 describes a method of making the thermoplastic compositions containing one or more thermoplastic resins and a phosphor, by mixing of these substances and extruding.

US patent application US2012233895 A1 proposes another method of condensation of the phosphor mixed with the binder, by the phosphor's heavy particles deposition in the mold when the phosphor and binder mixture is poured into the form. Although mixing of the phosphor particles with the binder reduces distances between the phosphor grains, there is still a surplus of empty space between the grains, filled with the binder, which is a cause of decreased strength of illumination.

The listed above prior art examples of methods of preparing the photoluminescent powder coatings and electrostatic methods for applying a photoluminescent powder coating, all these are the methods for multilayer coating or for application on wet base phosphor coating of further colorless coat, as well as for improving the adhesion of pre- applied basecoat by annealing the following layers before applying the next one on heated thereby prior coating layers or the phosphor itself, and final re-annealing of complex coating. These processes are expensive and time consuming, and difficult to achieve a uniform coating and uniform luminescence of the phosphor used. They are also energy intensive requiring several heating and annealing cycles of the painted item. Moreover, the disclosed methods lead to relatively low levels of luminescence of the coatings, insufficient for use in road construction and other fields. Structure of the luminescent layer causes the phosphor particles not adhere one to another at a suitable distance, which in turn resulted in significant decrease in luminance of the phosphor used. With the existing methods known in the prior art the phosphor particles are surrounded by a binder during mixing. This resulted in that it was not possible to obtain a high density of phosphor particles with a small distance between the individual particles in the phosphor layer. In addition, it must be emphasized that in the photoluminescent products made so far the luminescent layer always showed lower values of phosphorescence than the phosphor used to produce it.

The methods used so far do not ensure a multi-step transfer of excitation energy between molecules under the influence of light. It should be added that the coatings produced with the methods known in the prior art resulted in the layer thickness as big as 1.0 to 3.0 mm. The prior art discloses a solution, wherein the binder with adhesion promoters, improvers, and coloring powder was subjected to the mixing process at a predetermined temperature together with the phosphor particles, and the resulting mass was extruded, cooled and milled to the desired granulation, and thus the photoluminescent coating was obtained. As a result of mixing, extruding and milling all substrates together the luminance of the phosphor crystals was decreased because of formation of a thin outer layer limiting absorption of light.

The aim of the invention is to obtain a reflective photoluminescent powder paint, and a method of preparation of the reflective photoluminescent coating characterized by long-lasting luminance and phosphorescence, to be used as a renewable source of light for illumination of the surroundings without the need for electric energy supply to activate this effect.

The aim of the invention is therefore a composition of photoluminescent coating devoid of a coloring pigment used commonly for paints which shall be replaced by a phosphor pigment so that in daylight the coating has a color of the phosphor powder used, while in the evening and at night it shines with color of luminescence of the luminescent powder.

According to the invention, the reflective photoluminescent coating combines the effect of the phosphor luminance and the reflective effect, greatly improving the visibility of the coating. The proposed coating can be used for painting metal, glass, ceramic and plastic objects, for example furniture, auto parts, aluminum joinery, electrical equipment, housings of machines and various devices, lighting fixtures, household appliances, heating radiators, bicycles, ships, items for road safety such as barriers, signs, posts and other passive elements of road safety, as well as for painting elements of infrastructure of the human environment.

Proposed invention results in a greater percentage of the phosphor attained by replacing the commonly used paint pigments with the photoluminescent powder consisting of one or more color compositions, depending on the specific requirements, thereby resulting in the ability to produce an ultra-thin coat of paint in just one cycle of the coating fusing.

A method for producing a reflective photoluminescent coating according to the invention comprises: mixing a resin with an adhesion promoter and additives, heating the mixture to the molten state, extruding the mixture in a liquid state, cooling the mixture, pulverizing the extruded mixture to form a powder, milling the powder and finally adding the phosphor in powder form with mixing. Resin powder particles are selected, preferably of polyester, polyurethane, epoxy, mixed with the adhesion promoter and additives, that have a thickness of 10-350 μm (microns), preferably 10-200 μm, more preferably 33-195 μm. Also the phosphor powder particles having a thickness of 10-300 μm, preferably 30- 150 μm are selected.

Addition of reflective glass beads, preferably having a thickness of 10-300 μm, more preferably 30-150 μm, increases the reflective properties of the coating.

Adding of pigments to the mixture, in particular pigments which are also phosphors, provides the coating with the desired color. The particles of pigments have a thickness of preferably 10-350 μm, more preferably 10-300 μm, most preferably 24-150 μm.

It is desirable that the total volume fraction of the phosphor particles in the mixture was 30-65%, preferably 35%.

According to the claimed method an inner zone characterized by increased concentration of the phosphor particles is attained by reducing the distance between the grains until their mutual adhesion in the coating on the substrate side. This process is based on electrostatic interactions between electrically charged particles of the phosphor and the oppositely charged substrate. Both make an electric dipole.

In one option of the method the volume fraction of the phosphor particles in the mixture in the inner zone of the coating is 70-98% and preferably 90-98%, especially 92- 98%.

After application of the powder mixture to the substrate, the coating is turned to the liquid state, and then back from the liquid state to the solid state. An article coated with the coating is annealed in a chamber furnace or continuous furnace at 200 °C for 10 min., or at 180 °C for 15 min., or at 160 °C for 20 min. Then it is cooled, preferably at a temperature of 20 °C.

A reflective photoluminescent powder paint according to the invention comprises the powdered resin with the adhesion promoter and additives, and the phosphor powder mixed together. The powder particles of the resin, preferably a polyester, polyurethane, epoxy, mixed with the adhesion promoter and additives, have a thickness of 10-350 μm, preferably 10-200 μm, more preferably 33-195 μm, and the phosphor powder particles have

a thickness of 10-300 μm, preferably 30-150 μm.

In addition powder paint contains reflective glass beads, preferably with a thickness of 10- 300 μm, more preferably 30-150 μm.

Powder paint can also contain pigments, preferably phosphors providing the coating with the desired color. The pigment particles have a thickness of preferably 10-350 μm, more preferably 10-300 μm, most preferably 24-150 μm.

The total volume fraction of the phosphor particles in the mixture forming the powder paint is 30-65%, preferably 35%.

A method for producing a reflective photoluminescent coating allows for making its inner zone with high packing density of the phosphor particles and such an arrangement of these particles that they adhere to one another. The volume fraction of the phosphor powder in the inner zone of the coating is from 70% to 98%, and the remaining part is a binder and other additives. The invented method allows to increase photoluminescence of the phosphor layer used from 50% to 340% and at least from 50% to 90%. Prolonged phosphorescence and luminescence in comparison with prior art coatings is also achieved. This method makes possible to produce white paint coating without the use of white pigment (eg. Titanium dioxide TiO₂) as this pigment can be replaced with a white phosphor (luminescent white).

In the embodiment of the coating method according to the invention, by specifying a selected temperature in a chamber furnace or a continuous furnace the coating is fused, wherein the phosphor particles are arranged as close as possible in the inner zone with a volume concentration ranging from 70% to 98% of this zone. Transition of the binder from solid state in powder form into liquid state and back to a solid is applied, and the volume reduction accompanied by shrinkage of the coating is one of the mechanisms of concentration of the phosphor in the coating.

To make a photoluminescent coating one has to mix the two components of the binder, ie. a resin with a catalyst (promoter) of binding, f!uidizers and improvers. The prepared material is melted, extruded, and cooled to ambient temperature, and it is then ground to a predetermined grain thickness, preferably between 10 μm and 350 μm, more preferably from 30 μm to 150 μm. Finally the phosphor particles of a selected thickness are added to the powder.

If a reflective photoluminescent coating is required, the reflective beads are added, prepared e.g. from glass, and having a thickness of 10 to 350 μm, and preferably from 24 to 150 μm. The proportion of the reflective beads to the volume of the phosphor and binder particles ranges from 10% to 25%.

After application of prepared mixture on the coated object it is heated to a temperature of 160-200 °C and annealed for 10-20 minutes. It is also possible to apply the coating in liquid form by melting the powder in a gas flame or using a flameless method, and moving it in a liquid state on the coated item by means of compressed air. The painted element shall be placed in an air fluidized bed of powder at a temperature higher than the melting point of the powder.

To make a photoluminescent powder coating of enhanced phosphorescence of luminescent layer with a suitable arrangement of the phosphor particles, a suitable electrostatic charge is supplied to the powder during its application, and then it is heated to the liquid state in the chamber furnace or the continuous furnace. Electrically charged particles are deposited on the grounded object due to electrostatic induction. The phosphor particle charged with positive charge (frictional charging) or negative charge (voltage powder charging) is attracted by induced charge of opposite sign and deposited on the painted material. The particles remain charged and are suspended in the structure of dry binder grains. Concentration of phosphorescent particles in the inner zone of the coating may reach 70% to 98% and is based on mutual attraction of the substrate and the phosphorescent particles making an electric dipole.

In subsequent step of annealing deposited dry coating is heated until it is liquefied. The phosphor particles having a larger unit weight than the melted binder are deposited on the substrate first, because they are attracted to its surface by electrostatic charges. This results in a full absorption of the phosphor particles in the coating layer.

In next step of contraction of the binder the phosphor particles are further brought together. This process in combination with the interaction of electrostatic charges leads to a laminated composite fused by heating. The next step is removing the element outside the firing chamber and cooling at ambient temperature. In this step the photoluminescent paint is finally contracted acting on the phosphor particles suspended in the binder. The phosphor has a thermal resistance exceeding many times the temperature applied for annealing.

In this embodiment of the invention the method of forming a coating with use of the powder paint consists in applying the powder photoluminescent or reflective photoluminescent layer by electrostatic coating in one or two processes of layering the powder, and its consolidation takes place in a single thermal process.

An embodiment of the invention is illustrated in the accompanying drawings, where Fig. 1 shows a cross section through the reflective photoluminescent coating after electrostatic concentration of phosphor particles in a zone close to the substrate, wherein the state prior to densification, immediately after application of the coating to a substrate is shown in Fig. 2.

The applied powder coating of photoluminescent layer (Fig. 2) contains the phosphor particles mixed with particles of binder in the first phase after application with contact-and- friction charging. A positively-charged powder is deposited on the painted material. When placed in a chamber and heated to an appropriate temperature the processes occur as follows:

1 ) The binder liquefaction, followed by deposition of the charged phosphor and further attraction of the phosphor particles and laying next to each other under their own weight.

2) The cross-linking process.

3) Completion of the process and obtaining the finished product with high concentration and equal distribution of phosphor particles (Fig.1 ). As a result of excitation of ail the phosphor particles a fluorescent spontaneous emission of visible light occurs. The distance between adjoining phosphor particles cannot exceed 0.0015 μm (micron) up to 1 μm.

A process of energy transfer between the phosphor particles is faster as a result of packing of these particles, and this in turn increases the life time of molecules in the excited state and the strength of the lighting luminance (quantum efficiency) of produced coating with specified molar absorption coefficient, the integral absorption coefficient and value of transmittance.

Example 1

In a first embodiment the reflective photoluminescent coating, ultra-thin with a thickness of 35 microns, a transparent binder has been used, plus additives and phosphor of white base color (luminescence white), which gives off a light green color in the dark.

The coating in application had a thickness of 40-60 μππ (microns), and was applied on a steel plate approximately 30 cm x 50 cm.

The object surface was prepared for application of the powder paint with photoluminescent and reflective properties. The steel plate has been treated with pneumatic blasting-abrasive method and whitened.

Starting preparation

1 ) Polyester resin, e.g. POLICEN 3660 T

2) Crosslinkable hydroxyalkyl amide, e.g. PRIMID XL 552

3) Liquidation improving additive, polyacrylate-based anti-crater; supplier: e.g. BYK-366 P KRAHN CHEMIE

4) Phosphor, manufacturer: Lanxi Minhui Photoluminescent Co., Ltd.

5) Benzoin

6) Reflective beads with refractive index≥1 ,50 and grain size 25 μm.

Formula;

This example was made to a product based on the starting preparation prepared in accordance with the following procedures. Mixing MIXACO CM6 3 min / 1000 rpm; the twin screw extruder, screw speed of 500 rpm, softening zone temperature of 25 °C, melting zone temperature of 70 °C, the zone outlet temperature of 115 °C, the mass temperature of 125-135 °C; components: POLICEN 3660 T Primid XL 552, BYK-366 P, Benzoin.

The thus prepared material was milled in a planetary ball mill PM 100 to produce a grain of 35 microns.

A phosphor of particle size of 15-35 μm, and reflective glass beads of particle size of 25 μm were added with stirring to the resulting powder. A mixer Plasmec TRL was used to mix all the basic ingredients, and the resulting substance was applied to the prepared substrate by frictional triboelectrization.

Then the substrate was fired in the chamber furnace or the continuous furnace at 200 °C for 10 min. A well-fixed paint coating was obtained.

Measurement of luminance

Terms of calibration: measuring the luminance of light and the decay time of phosphorescence after samples exposure to xenon lamp with a power of 150 W for 5 minutes from a distance of 80 cm. The value of light intensity on the sample surface was 1000 Ix. The measurement was performed in accordance with the requirements of Polish industrial standard PN-92/N.

Time after which the light luminance of the sample reached the limit 0,32 mcd/m² was measured.

Example 2

Manufacture of photoluminescent powder coating of thickness equal to 80 microns, white in the day and light green of the phosphor lighting at night, and the application of this paint at a thickness of the applied coating of 40-90 microns on an aluminum plate approximately 30 cm x 50 cm.

The plate surface was prepared for application of the powder paint with photoluminescent and reflective properties. The treatment of the aluminum plate was made by degreasing and mechanical cleaning with fine grit sandpaper and then washed with isopropyl alcohol and dried.

Starting preparation:

1 ) Polyester resin, e.g. POLICEN 3660 T

2) Crosslinkable hydroxyalkyl amide, e.g. PRIMID XL 552

4) Phosphor, manufacturer: Lanxi Minhui Photoluminescent Co., Ltd.

5) Benzoin

Formula:

The thus prepared material was milled in a planetary ball mill PM 100 to produce a grain of 35-80 microns.

A phosphor having a particle size of 65-75 microns was added with stirring to the resulting powder, mixer Plasmec TRL was used for mixing.

The resultant powder paint was applied to the prepared surface using high voltage electrostatic air-spray method of 40-100 kV.

The material was then fired in the chamber furnace or continuous furnace at a temperature of 180 °C for 15 min. A ready well-fixed paint coating was obtained.

Measurement of luminance

Examnple 3

Fabrication of the photoluminescent powder coating of the film thickness of 80 μm, white light-emitting phosphor on the day, and yellow-green at night, and application of this paint at a thickness of the applied coating of 40-90 microns on an aluminum plate approximately 30 cm x 50 cm.

The surface was prepared for application of the powder paint with photoluminescent and reflective properties. The treatment of the aluminum plate was made by degreasing and mechanical cleaning with fine grit sandpaper, and then the plate was then washed with isopropyl alcohol and dried.

Starting preparation:

1 ) Polyester resin, e.g. POLICEN 3660 T

2) Crosslinkable hydroxyalkyl amide, e.g. PRIMID XL 552

4) Phosphor, manufacturer: Lanxi Minhui Photoluminescent Co., Ltd.

5) Benzoin

A coating was pre-prepared for the use of two phosphors:

a) yellow-green phosphor Lanxi Minhui Photoluminescent Co. Ltd., phosphor MHG -4 B 65-75 μm - paint coating;

b) white light green phosphor M S G G-4 D 10 28 Mm - primer. The primer was applied as a first paint layer, and it was covered with a layer of white primer, which resulted in a reflective screen made of luminescent paint with a binder and additives.

Two coats were made by applying a first paint "B" and second coating "A". In the process of curing the applied first coating of much smaller luminescent particles adheres to the substrate first, forming a white screen reflecting the glow of phosphorescent second coating, thus improving the overall luminance of the coating.

Formula:

Final coatin

Primer

All examples was made to a product based on the starting preparation prepared in accordance with the following procedures. Mixing MIXACO CM6 3 min / 1000 rpm; the twin screw extruder, screw speed of 500 rpm, softening zone temperature of 25 "C, melting zone temperature of 70 °C, the zone outlet temperature of 115 °C, the mass temperature of 125-135 °C; components: POLICEN 3660 T Primid XL 552, BYK-366 P, Benzoin.

A phosphor having a particle size of 65-75 microns (The phosphor MSGG-4D 10 28 μm ) was added with stirring to the resulting powder, mixer Plasmec TRL was used for mixing.

The resultant paint was applied to the prepared material. The method of applying was the high voltage of 40-100 kV electrostatic method.

Then the material was fired in the chamber furnace or continuous furnace at 160 °C for 20 min. A fixed paint coating was achieved.

Measurement of luminance

Example 4

A photoluminescent powder coating having a paint film thickness of 1 .5 mm and the light yellow-green color of phosphor at day, and yellow-green at night, and application of this paint at a thickness of 1.8-2.0 mm of the applied coating on the substrate using vacuum forming. The mold surface was prepared by a known method.

A binder with additives and a phosphor MGH 6 BA 50-150 μm Lanxi Minhui Photoluminescent was sprayed with a spray gun using electrostatic method on the prepared mold for powder casting. Vacuum forming was based on placing over the form of a shaped sheet of polymer in any, preferably light color, heating it and turning on the vacuum system, which removes air from the space between the mold and the material, thus injecting the heated material into the mold by means of air pressure.

The layer of phosphor with binder and additives has been moved this way on the shell- shaped element. Finished piece was covered with a layer of luminescent powder on 1 % to 100% of the surface. It can be further processed by painting, varnishing, imposing an additional color with traditional paints, etc.

The powder layer thickness was 50-150 μm in 1 % volume of 300 μηι, the applied thickness was 1.5 mm.

Measurement of luminance

The phosphor applied was MGH 6 BA with molecular formula: SrAI₂O₄:Eu+2,Dy+3.

Measurements were made with precise luxmeter L-100 and contact luminance meter PL- 68.

In the described above embodiments of the photoluminescent powder coating and reflective photoluminescent powder coating the phosphor particles are arranged spatially to one another, so that there is energy transfer between all particles which results in a longer, non-exponential decay of luminescence in the luminescent matrix.

Explanation of terms used herein:

"Coating" - a layer of binder with additional ingredients, in solid state or liquid state during the heating process;

"Phosphor", "photoluminescent powder" - any substance or material having photoluminescent properties, usually a mixture of oxides, sulfides, selenides, silicates and orthophosphates (V) of alkaline earth metals, zinc and cadmium, including activators, e.g.: SrAI₂O₄:Eu+2,Dy+3.

Claims

1. A method for producing a reflective photoluminescent coating, characterized in that it comprises the stages of: mixing a resin with adhesion promoter and additives, heating the mixture to the molten state, extruding the mixture in a liquid state, cooling the mixture, pulverizing the extruded mixture to form a powder, the powder grinding and adding a phosphor in the powder form with mixing.

2. The method of claim 1 characterized in that the powder particles of a resin, preferably of polyester, polyurethane, epoxy, mixed with the adhesion promoter and additives have a thickness of 10-350 μm , preferably 10-200 μητι, more preferably 33-195 μm , and the powder particles of the phosphor have a thickness of 10-300 μm, preferably 30-150 μτη.

3. The method of claim 1 or 2, characterized in that it comprises the stage of addition of reflective giass beads, preferably having a thickness of 10-300 μm , more preferably 30- 150 μm .

4. The method of claim 1 or 2, or 3 characterized in that the pigments are added to the mixture, preferably the phosphors giving the coating the desired color, the particles of phosphors having preferably a thickness of 10-350 μm , more preferably 10-300 μm , most preferably 24-150 μm .

5. A method according to any of claims 1 to 4, characterized in that the total volume fraction of the phosphor particles in the mixture is 30-65%, preferably 35%.

6. A method according to any of claims 1 to 5, characterized in that an inner zone of an increased concentration of the phosphor particles is produced in the coating on the substrate side by reducing the distance between these particles using the electrostatic interaction between the phosphor particles and the substrate.

7. The method of claim 6, characterized in that in the inner zone of the coating the volume fraction of the phosphor particles in the mixture is 70-98%.

8. The method of claim 6, characterized in that in the inner zone of the coating the volume fraction of the phosphor particles in the mixture is 80-98%, preferably 92-98%.

9. A method according to any of claims 1 to 8, characterized in that after appiication of the coating of powder mixture to a substrate it is carried out to the liquid state and then from the liquid state to the solid state.

10. A method according to any of claims 1 to 9, characterized in that the article coated with the coating is fired in a chamber furnace or a continuous furnace at 200 °C for 10 min., or at 180 °C for 15 min., or at 160 °C for 20 min., then it is cooled, preferably at a temperature of 20 °C.

1 1. A reflective photoluminescent powder paint characterized in that it comprises a powdered resin mixed with an adhesion promoter, additives, and a phosphor powder.

12. The powder paint according to claim 11, characterized in that the powder particles of the resin, preferably a polyester, polyurethane, epoxy, mixed with the adhesion promoter and additives have a thickness of 10-350 μm, preferably 10-200 μm, more preferably 33- 195 μm , and the phosphor powder particles have a thickness of 10-300 μm , preferably 30-150 μm.

13. The powder paint according to claim 11 or 12, characterized in that it comprises the reflective glass beads, preferably having a thickness of 10-300 μηη, more preferably 30- 150 μm .

14. The powder paint according to claim 1 1 or 12, or 13, characterized in that it comprises pigments, preferably the phosphors giving the coating the desired color, the particles of which preferably have a thickness of 10-350 μm , more preferably 10-300 μm, most preferably 24-150 μm.

15. The powder paint according to any of claims 11 to 14, characterized in that the total volume fraction of the phosphor particles in the mixture is 30-65%, preferably 35%.