RU2612705C1 - Method for producing film luminophore based on acrylic polymer - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: acrylic base is mixed with the isostationate hardener at the ratio of 1:1, from 0.5 to 2 wt % titanium nanodioxide with a grain size up to 50 nm is added. The mixture is maintained within 3-3.5 hours with continuous stirring, luminophore is added in an amount providing the necessary colour coordinates, and stirred for another 30-40 minutes. The luminophore is represented by Y₃Al₅O₁₂:Ce, Lu₃Al₅O₁₂:Ce, Gd₃Al₅O₁₂:Ce. The mixture is then poured onto a polypropylene pad of a desired shape and maintained in air to the polymerization state. The film is separated from the polypropylene base and finally dried in a drying cabinet at 110-120°C.

EFFECT: method improvement.

4 cl, 1 tbl, 10 dwg, 3 ex

Description

The invention relates to the field of synthesis of remote phosphors that can be used to create LEDs with the necessary color coordinates, in particular for white LEDs. There are many known applications of LEDs using a remote phosphor. We can distinguish such a field as lighting engineering (fluorescent lamps, lamps, car headlights, architectural and design lighting, greenhouse lighting, etc.).

State of the art

There are a number of ways to create remote phosphors. A known method of creating a remote phosphor based on optical silicone fill and phosphor (M. V. Voropaev, D. D. Karimbaev, Yu. A. Hotnenok, A. P. Kokhanenko, V. A. Kharenkov. Thermal analysis of LED matrices of the visible range with silicone fill and phosphor // Doklady TUSURa, No. 2 (26), part 2, 2012). The removed phosphor is an optically transparent silicone fill and the phosphor layer covering it (Fig. 1, where 1 is the body, 2 is the crystal holder, 3 is the light emitting crystal, 4 is the phosphor particles, 5 is the transparent optical silicone).

This design is located on top of the printed circuit board with crystals of blue radiation, mounted on it. There are a number of luminaires with different consumed electrical powers: 6.10, 30.40, 60, 80, 95 and 100 watts.

The disadvantage of luminaires based on a remote phosphor with an optically transparent silicone fill is that the optical silicone fill of the LED matrix is destroyed under the influence of high temperatures caused by high powers. It should be noted that the fading of optical silicone, which negatively affects the luminous efficiency of the LED device, begins to occur at temperatures from 300 ° C. The results of calculations and measurements showed that for the power consumption of a lamp of 40 W, the temperature on the surface of an LED device of a similar design is above 200 ° C.

There is a way to create a remote phosphor based on inorganic glass ceramics (M. A. Shvaleva, A. E. Romanov, V. A. Aseev, N. V. Nikonorov, K. D. Mynbaev, V. E. Bugrov. Optical and thermal properties phosphors based on lead-silicate glass for high-power white LEDs // Letters in ZhTF, vol. 41, issue 21, 2015). The glass-ceramic composition, ground to a uniform powder state, is mixed with the YAG phosphor: Ce3 ⁺ in the required proportions and glass-ceramic samples are formed under pressure. Glass ceramics are sintered at the required temperatures and as a result, glass crystallite is obtained, which is a remote phosphor for an LED with blue radiation crystals. The temperature resistance of such a remote phosphor is high, but the disadvantage is that the technology of its creation is rather laborious, since it requires high pressure when forming glass ceramic samples ~ 4 ~10 ⁸ Pa. Also, the necessary sintering temperatures are ~ 550 ° C. In addition, the quantum efficiency of such a remote phosphor is 80-90% of the effectiveness of the silicone phosphor composite, with a high content of expensive 50-90% YAG: Ce3 ⁺ .

Closest to the proposed method is a technology for producing luminous surfaces based on fluorescent paints (Y.N. Kovalev, V.N. Yaglov, N.A. Krechko, Yu.V. Shagoyko. Glowing paints // Construction Science and Technology, 2010) . Organic phosphor is mixed with colorless (transparent) varnishes. Next, the resulting paint is applied to the surface in any convenient way.

The use of these compositions in the manufacture of lighting devices is unknown. The use of organic phosphors gives reason to assume a low temperature resistance of such compositions.

The objective of the invention was to develop a less time-consuming method for producing films, used, in particular, for the manufacture of remote phosphors, which would have increased light efficiency and temperature resistance.

The technical result of the invention is: increasing light efficiency, temperature stability and increasing the life of light-emitting devices when using films with a phosphor.

The problem is solved in that the film is created on the basis of heat-resistant polymer acrylic resins, an isostationate as a hardener, an additive in the form of titanium nanodioskide, which increases the refractive index, and the corresponding phosphor.

The preparation of the polymer base is carried out according to the well-known technology (P.G. Konovalov, V.V. Zhebrovsky, V.V.Shneyderova // Laboratory workshop on the chemistry of film-forming and the technology of varnishes and paints, ROSVUZIZDAT, 1987).

The basis of the polymer in the form of acrylic resins is prepared as follows.

360 g of commercial butyl methacrylate are placed in a flask equipped with a stirrer, which is washed with 100 ml of a 7-9% aqueous solution of sodium hydroxide (400 ml of water and 28-36 g of NaOH), filtered through a mesh, stirred for 10-15 minutes; after settling for 15-20 minutes, the lower layer is lowered; such washing of butyl methacrylate with an alkali solution is carried out at least 3 times.

After washing the butyl methacrylate with an alkali solution, the presence of the hydroquinone inhibitor in the butyl methacrylate is checked by sampling it and adding a 10% aqueous solution of caustic soda in a 1: 1 ratio (by volume of butyl methacrylate to alkali). The absence of staining of the taken alkali indicates the completeness of removal of hydroquinone. In the presence of staining (yellow tint), butyl methacrylate is further treated with an alkali solution until the inhibitor is completely removed. After removal of hydroquinone, butyl methacrylate is washed with water until the alkali is completely removed. For this, 100 ml of water is introduced into a flask with butyl methacrylate, the whole mass is stirred for 10-15 minutes, then it is left to stand for 15-20 minutes; the aqueous alkali solution is lowered. Washing is carried out until a neutral reaction of washing water with phenolphthalein is obtained. After about three washes, the wash water reaction should be neutral.

After washing, butimethacrylate is dried with anhydrous sodium sulfate (until a light product is obtained). Dry butyl methacrylate, purified from hydroquinone, is filtered through a cloth.

The following is the production of acrylic polymer

Benzene peroxide for making in the polymerization apparatus is prepared according to the instructions for handling benzene peroxide. The required amount of dehydrated benzoyl peroxide is dissolved in butyl methacrylate.

White spirit and butyl methacrylate are added in a 1: 1 ratio to a flask equipped with a refrigerator and a stirrer. With the stirrer working, benzoyl peroxide dissolved in butimethacrylate is gradually poured there. Turn on the heating, the temperature is raised to 70-85 ° C and maintained for 1.0-1.5 hours. The polymerization process is accompanied by heat, and the temperature spontaneously rises to 85-90 ° C. To prevent the temperature from rising above 90 ° C, cooling is periodically turned on.

The duration of polymerization, counting from the beginning of a spontaneous rise in temperature, is 6–9 hours. The whole polymerization process is carried out with the stirrer working. Next, the solution is poured into a porcelain glass.

Disclosure of invention

According to the invention, the acrylic base is kneaded with a hardener isostationate in a ratio of 1: 1, after which from 0.5 to 2 weight% of titanium nanodioscide with a grain size of up to 50 nm is added and incubated for 3-3.5 hours. During the exposure, the entire mixture is constantly mixed under the action of a rotating mixer in the form of a rod with blades at the end. Then, a phosphor is added to the resulting mixture in proportion to the required color coordinates (for example, for a device based on a blue chip and a remote phosphor) and this mixture is stirred for another 30-40 minutes. Next, the mixture is poured onto a polypropylene pad of the desired shape with perimeter edges that have a height sufficient so that the mixture does not overflow overboard. After this, a 12-15-hour exposure to air takes place to dry the mixture and take shape. Next, the polymer light-emitting film is separated from the polypropylene substrate and dried in an oven for 2-2.5 hours at a temperature of 110-120 ° C. After drying, the film is removed and packaged in the required form.

Justification of new features

The specified ratio of hardener to acrylic base is optimal, if the hardener is less, the plasticization process is extended, if there is more hardener, the film is brittle.

The choice of the concentration of titanium nanodioxide is explained by the effect on the refractive index of the film and is obtained from the experimental data shown in table 1. The effect of the concentration of the titanium oxide additive on the refractive index of the film based on acrylic resins without a phosphor is experimentally established, the results are shown in table 1. As can be seen from table , at an additive concentration below the lower boundary, no effect is observed; at an additive concentration above the upper boundary, a decrease in the refractive index is observed. Given this fact, the following examples use an additive in the amount of 0.2 grams of titanium oxide, corresponding to the maximum refractive index.

The choice of the grain size of titanium nanodioxide (up to 50 nm) is explained by the fact that this size is optimal for the transmittance of the films at which 100% transmittance is maintained. At a particle size greater than 50 nm, a decrease in the transmittance of light for films without an added phosphor begins to occur.

This method allows to obtain an acrylic polymer film with a phosphor of the required length and thickness, which can be rolled up, which makes this material compact for transportation and storage. This acrylic film is easily consistent with the surface of the radiating element, forming with it a structure with a removed phosphor.

Examples of obtaining a film based on a polymer of acrylic resins

Example 1. Prepare the basis of the polymer in the form of acrylic resins.

Next, 5 g of the base are mixed with a hardener isostationate in a 1: 1 ratio in a porcelain bowl, after which 0.2 g of titanium nanodioxide (particle size 50 nm, manufactured by Evonik Industries, Germany) is added. The mixture was incubated for 3 hours, with constant stirring. Then, 1 g of the phosphor Y ₃ Al ₅ O ₁₂ : Ce is added to the resulting mixture, and this mixture is stirred for another 35 minutes. Next, the mixture is poured onto a polypropylene pad of the desired shape with perimeter edges that have a height sufficient so that the mixture does not overflow overboard. After this, exposure to air occurs for 13 hours, so that the mixture is dried and takes shape. Then the film is separated from polypropylene and dried in an oven for 2 hours at a temperature of 110 ° C.

After drying, the polymer acrylic film with the phosphor has an average thickness of 130 μm, the refractive index is 1.80. The color coordinates of the remote phosphor when illuminated with a blue LED (wavelength 450 nm) fall into the bin of white light (x = 0.343, y = 0.338). The luminous efficiency of the remote phosphor was 160 Lm / W.

The comparison was carried out under the same conditions with the light output of the initial phosphor Y ₃ Al ₅ O ₁₂ : Ce mixed with optical silicone (DOW CORNING OE-6630 brand, USA), which was 120 Lm / W.

The resulting film phosphor is temperature-resistant at 320 ° C; above this temperature, the polymer acrylic film is destroyed.

The visual image of the removed phosphor is shown in Fig. 2. The illuminated spectrum of the remote phosphor combined with the blue LED is shown in Fig. 3. Electron microscopy of a remote phosphor is shown in Fig. four.

Example 2. Prepare the basis of the polymer in the form of acrylic resins.

Next, the film-based remote phosphor was prepared according to Example 1, while the addition of titanium nanodioxide (particle size 50 nm, manufactured by Evonik Industries, Germany) was 0.2 g; Lu ₃ Al ₅ O ₁₂ : Ce, taken in an amount of 1 g, was used as a phosphor .

After drying, the polymer acrylic film has an average thickness of 130, the refractive index is 1.77. The color coordinates of the remote phosphor when illuminated by a blue LED (wavelength 450 nm) fall into the bin of green light (x = 0.388, y = 0.563). The luminous efficiency of the remote phosphor was 150 Lm / W.

The comparison was performed under the same conditions with the light output of the initial phosphor Lu ₃ Al ₅ O ₁₂ : Ce in a mixture with optical silicone (brand DOW CORNING ОЕ-6630, USA) which was 110 Lm / W.

The resulting film phosphor is temperature-resistant at 320 ° C; above this temperature, the polymer acrylic film is destroyed.

The visual image of the removed phosphor is shown in Fig. 5. The highlighted spectrum of the remote phosphor combined with the blue LED is shown in Fig. 6. Electron microscopy of the removed phosphor is shown in Fig. 7.

Example 3. Prepare the base of the polymer in the form of acrylic resins.

Next, the film-removed phosphor was prepared according to Example 1, with the addition of titanium nanodioxide (particle size 50 nm, manufactured by Evonik Industries, Germany) being 0.2 g; Gd ₃ Al ₅ O ₁₂ : Ce, taken in an amount of 1 g, was used as a phosphor .

After drying, the polymer acrylic film has an average thickness of 130 μm, the refractive index is 1.79. The color coordinates of the remote phosphor when illuminated with a blue LED (wavelength 450 nm) fall into a bin of white light (x = 0.350, y = 0.352). The luminous efficiency of the remote phosphor was 140 Lm / W.

Comparison was made under the same conditions with the light output of the initial phosphor Cd ₃ Al ₅ O ₁₂ : Ce mixed with optical silicone (DOW CORNING OE-6630 brand, USA), which was 100 Lm / W.

The resulting film phosphor is temperature-resistant at 320 ° C; above this temperature, the polymer acrylic film is destroyed

The visual image of the removed phosphor is shown in Fig. 8. The highlighted spectrum of the remote phosphor combined with the blue LED is shown in Fig. 9. Electron microscopy of a remote phosphor is shown in Fig. 10

Claims (4)

1. A method of creating a film phosphor based on an acrylic polymer, characterized in that the acrylic base is mixed with a hardener isostationate in a ratio of 1: 1, add from 0.5 to 2 weight% of titanium nanodioxide with a grain size of up to 50 nm, incubated for 3 -3.5 hours with constant stirring, add a phosphor, taken in proportion depending on the required color coordinates, and this mixture is stirred for another 30-40 minutes, after which it is poured onto a polypropylene pad of the desired shape and kept in the air until the polymer izatsii, then the film is separated from the propylene base and dried in an oven at a temperature of 110-120 ° C. 2. The method according to p. 1, characterized in that as the phosphor use Y ₃ Al ₅ O ₁₂ : Ce. 3. The method according to p. 1, characterized in that as the phosphor use Lu ₃ Al ₅ O ₁₂ : Ce. . 4. A method according to claim 1, characterized in that the phosphor is used as Gd ₃ Al ₅ O _12: Ce.

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