RU2549406C1 - Polymer luminescent composite for colourless light production, which is excited by blue light-emitting diode - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: invention is referred to light engineering, in particular to polymer luminescent composites used for arrangement of general and local lighting. The polymer luminescent composite excited by blue light-emitting diode contains transparent polycarbonate with melt flow index of 6-40 g/10 min, photoluminiscent phosphor - yttrium- gadolinium alumogallic garnet activated by cerium with formula of (YGd)₃(AlGa)₅O₁₂:Ce, powdered polyethylene wax with particle size of 18-30 mcm, heat stabiliser - Ultranox 626 and Tinuvin 360.

EFFECT: suggested composite provides reduced intensity of blue light and increased illumination.

6 dwg, 2 tbl, 14 ex

Description

The invention relates to lighting engineering, in particular to polymer luminescent compositions used for the manufacture of devices for general and local lighting.

There are three ways to get white light from a light source. The first is color mixing according to the technology, according to which red, blue and green light sources are densely placed on one matrix, the radiation of which is mixed using an optical system, such as a lens.

The second method is that on the surface of a light source emitting in the UV range, three phosphors are emitted, emitting blue or green, or red light.

The third method uses a different approach - the use of two opposite colors on the color chart of the International Commission on Lighting (CIE). When a blue diode crystal is coated with a yellow phosphor, in which light is excited by blue radiation, the addition of colors gives a white glow. Gallium nitride is usually used as a crystal of a light emitting diode (LED), and a compound based on garnet activated by cerium is used as a photoluminophore (J. "Lighting Engineering", No. 6, p.15, 2004).

A known polymer composition for lighting purposes containing an epoxy binder in which luminescent pigments with a particle size of less than 20 μm are selected, selected from the group of phosphors based on garnet of the general formula A ₃ B ₅ O ₁₂ : M, where A is an element selected from the group consisting of yttrium, gadolinium, lutetium; B is an element selected from the group consisting of aluminum, gallium; M is an element selected from the group consisting of cerium, europium, chromium. A material based on this composition is used to produce white light from a diode emitting a blue spectral range of light. The composition contains epoxy resin (60 wt.%), Luminescent pigment (<25 wt.%), Mineral filler (<10 wt.%), Excipients (5 wt.%), Such as liquid silicone wax and alkoxysilane, as hydrophobic reagent and adhesive, respectively (US Patent No. 6277301, C09K 11/02, publ. 21.08.2001).

A method of preparing said composition comprises dissolving a dry luminescent substance in high boiling alcohol and mixing with a liquid epoxy resin. The composition is applied to the body of the LED and protects it.

The known composition is characterized in that it is excited by the blue, UV or green light of the LED and puts it in the yellow spectral range. The total radiation of the proposed composition gives a white light.

The disadvantages of the composition include:

a) the need to create a sealed volume to protect against environmental influences; since the composition is non-forming, it must be protected with a lens made of hard, durable polymer or glass;

b) the phosphor composition is located directly on the LED, which leads to a high light and heat load, degradation of the phosphor, a decrease in the light flux of the LED structure and, as a result, to a change in the lighting characteristics of the structure during operation.

These disadvantages are eliminated in the luminescent polymer composition to produce white light excited by a blue LED, which is closest in technical essence and the achieved effect to the proposed and adopted as a prototype (Russian patent No. 2405804, IPC C09K 11/02, 78, 80; C08K 3/18 , published on December 10, 2010, valid on September 10, 2013).

The composition of the prototype is form-stable and is characterized by reduced heat load.

The composition of the composition according to the prototype (parts by weight): a transparent polymer (100), a photoluminophore based on garnet Y ₃ Al ₅ O ₁₂ : Ce (yttrium aluminum garnet) or Gd ₃ Al ₅ O ₁₂ : Ce (aluminum gadolinium garnet), or based mixtures of these compounds (1.5-5.0), polyethylene wax in the form of a powder with a particle size of 18-30 microns (0.1-0.7) and a stabilizer (0.2-1.0).

As a transparent polymer, the composition preferably contains polycarbonate of various grades with a melt flow rate of 3-60 g / 10 min, for example, Novarex 7030PJ (manufactured by Bayer AG), Carbotex K-20MRA (manufactured by Kotec, Japan), Iupilon H -4000 (manufacturing company Mitsubishi, Japan).

The garnet-based photoluminophores mentioned above can be used coated with, for example, zinc silicate or phosphate.

As a stabilizer (thermostabilizer), the composition may contain compounds from the group of sterically hindered phosphites - bis (2,4-di-tert-butyl) pentaerythritol diphosphite under the brand name Ultranox 626, bis (2,4-dicumylphenyl) pentaerythritol diphosphite under the brand name Doverfos S9226 or tri (2,4-di-tert-butylphenyl) phosphite under the trademark Irgafos 168; bis (2,4-di-tert-butyl) pentaerythritol diphosphite under the trade name Ultranox 626 is preferred.

The characteristics of the composition — chromaticity coordinates (x, y), color temperature, illumination, and blue light emission intensity — were measured on a device consisting of a photometric ball and a spectrocolorimeter as the main structural element of a lighting device for measuring light flux and colorimetric parameters of samples (TKA - spectrocolorimeter VD / 02 "company" TKA ", St. Petersburg).

The flow rates of polymer melts are measured according to GOST 11645-73.

The values of the lighting parameters of the composite materials of the prototype:

x = 0.352 to 0.385; y = 0.338 to 0.384;

illumination, lux - from 380 to 450;

color temperature, ° K - from 3800 to 4800.

The disadvantages of the composition of the prototype should include a significant range of blue light in the light visible to the human eye.

Blue light begins the visible range of solar radiation. It includes light waves with a wavelength of 380 to 500 nm. The name “blue light” is essentially simplified, since it covers light waves starting from the violet range (from 380 to 420 nm) and the blue itself (from 420 to 500 nm). Since blue waves have the smallest length, they - according to the laws of Rayleigh light scattering - are most intensively scattered, so a significant part of the annoying brilliance of solar radiation is due to blue light. Under the same exposure conditions, blue light is 15 times more dangerous for the retina than the rest of the visible light (Veko-Optika. Catalog of articles, http://veko-optika.my.ru/publ/chem/chem_opasen_sinij_svet/ 1-1-0 -19 07/10/2013).

At present, the damaging effect of blue light on photoreceptors and retinal pigment epithelium has been proven. Blue light causes a photochemical reaction that produces free radicals that have a damaging effect on photoreceptors - cones and rods. The metabolic products formed as a result of the photochemical reaction cannot be properly utilized by the retinal epithelium - they accumulate and cause its degeneration. The French Food, Environmental and Occupational Safety Agency has published a report entitled “LED Lighting Systems: Health, Issues to Consider,” which among the issues of greatest concern are the toxic effects of blue light and the risk of dazzle, adding that blue light causes "Toxic stress" in the retina. (“KABEL-news”, No. 2, 2012. p. 50, 56. www.kabel-news.ru).

The technical task of the invention is to create polymer luminescent compositions excited by a blue LED, providing an environmentally friendly spectrum of visible light.

The technical result, which consists in obtaining a composition characterized by a significant decrease in the intensity of blue light in the range of emitted visible light and increased illumination, is achieved by the fact that the polymer luminescent composition for producing white light, excited by a blue LED, including transparent polycarbonate, a photoluminophore of aluminum-yttrium type, activated by cerium, polyethylene wax in the form of a powder with a particle size of 18-30 microns and a heat stabilizer, contains polycarbonate as polycarbonate a bonate with a melt flow rate of 6–40 g / 10 min, yttrium-gadolinium gallium aluminium garnet activated with cerium as the phosphor, formulas (YGd) ₃ (AlGa) ₅ O ₁₂ : Ce, thermal stabilizer Ultranox 626 and additionally Tinuvin 360 in the following the ratio of the components of the composition, parts by weight:

Polycarbonate one hundred Photoluminophore 1,5-7 Wax 0.1-0.7 Ultranox 626 0.2-1.0 Tinuvin 360 0.15-0.3

The composition is prepared by dusting the polymer granules primarily with wax, in the second with a mixture of Ultranox 626 and Tinuvin 360, in the third with a photoluminophore, followed by thorough mixing of the starting components.

Composite material is produced by high-performance methods of polymer processing - injection molding using backpressure to ensure uniform distribution of components in the polymer matrix melt on an injection molding machine, for example, ALLROUNDER 320K 700-250 from Arburg Maschinenfabrik Hehl & Sohne, which contributes to the design of the material into various required configurations;

- extrusion using any single or twin screw extruder, preferably with a ratio of length to diameter L / D 25-40.

The invention is illustrated by examples 1-8 (optimal example 2) in accordance with the invention, example 9 in accordance with example 11 is the best example of the prototype and control examples 10-14.

Example 10: the composition is similar to the optimal example 2, but using another heat stabilizer - Irgafos 168; example 11: the composition is similar to the optimal example 2, but without the use of polyethylene wax; example 12: a composition different from example 3 using photoluminophore in an amount that goes beyond the stated upper limit; Example 13: the composition includes only polycarbonate and photoluminophore; Example 14: The composition includes only polycarbonate and Tinuvin 360.

Example 1

Polycarbonate brand Makrolon QL 2647 with PTR 10-12 in the amount of 100 parts by weight dusting 0.1 wt.h. wax, then the resulting mixture was dusted with a mixture of Ultranox 626 (0.2 parts by weight) and Tinuvin 360 (0.15 parts by weight), after which 1.5 parts by weight were added. photoluminophore (YGd) ₃ (AlGa) ₅ O ₁₂ : Ce.

All components are mixed in a Turbula System Shatz (WAB) mixer (type “drunk barrel”) for 10 ± 5 minutes, after which the composition is formed into material (product) on an ALLROUNDER 320K 700-250 injection molding machine.

Compositions and composite materials according to examples 2-3 and 5-6 are made analogously to example 1.

Example 4

Polycarbonate brand Makrolon 3100 with PTR 6-7 in the amount of 100 parts by weight dusting 0.3 wt.h. wax with a particle size of 18 microns. The resulting mixture was dusted with a mixture of 0.5 wt.h. Ultranox 626 and 0.2 parts by weight Tinuvin 360, and then add 4.0 wt.h. (YGd) ₃ (AlGa) ₅ O ₁₂ : Ce. All components are mixed in a Turbula System Shatz (WAB) mixer (“drunk barrel” type) for 10 ± 5 minutes, after which the composition is formed into a material (product) in a Labtech Scientific LTE-20-40 twin-screw extruder from Labtech Engineering Company LTD ( Thailand).

The compositions of the compositions are shown in table 1, and the properties of polymeric materials (products) in table 2 and diagrams of the emission spectra of polycarbonate and compositions based on it (figure 1-figure 6):

- Figure 1 - in accordance with example 2 (optimal) of the invention;

- Figure 2 - in accordance with example 11 (optimal) of the prototype;

- Figure 3 - pure polycarbonate brand Makrolon QL 2647;

- Figure 4 - a mixture of Makrolon QL 2647 and photoluminophore (example 13);

- Figure 5 - a mixture of Makrolon QL 2647 and Tinuvin 360 (example 14);

- 6 - a mixture of Makrolon QL 2647 and wax.

Wax in the composition plays the role of not only a technological additive that improves the distribution of the photoluminophore, but also an additive that helps diffuse light, but does not have any effect on the conversion of light emitted by the LED, including a decrease in the intensity of blue light (Figure 6).

Table 1 The compositions Composition components The number of components in the examples, parts by weight according to the invention prototype control one 2 3 four 5 6 7 8 9 10 eleven 12 13 fourteen Polycarbonate: PTR, g / 10 min Makrolon QL 2647 10-12 one hundred one hundred one hundred one hundred one hundred one hundred one hundred one hundred one hundred Makrolon2400 18-20 one hundred Makrolon 3100 6-7 one hundred Lexan ML 3729 39 one hundred Carbotex K-20MRA twenty one hundred one hundred Photophosphor (YGd) ₃ (AlGa) ₅ O ₁₂ : Ce 1,5 4.0 7.0 4.0 4.0 4.0 4.0 4.0 4.0 8.0 4.0 (YGd) ₃ (AlGa) ₅ O ₁₂ : Ce modified with phosphate coating 4.0 Y ₃ Al ₅ O ₁₂ : Ce 2.1 Gd ₃ Al ₅ O ₁₂ : Ce 2.1 Wax polyethylene, powder Particle size, microns eighteen 0.1 0.3 0.7 0.3 0.3 0.3 0.3 0.5 0.3 0.7 thirty 0.5 Ultranox 626 0.2 0.5 1,0 0.5 0.5 0.5 0.5 0.5 1,0 0.5 1,0 Irgafos 168 0.5 Tinuvin 360 0.15 0.2 0.3 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.3 0.2

table 2 Lighting parameters of composite materials Indicators Examples one 2 3 four 5 6 7 8 9 prototype 10 eleven 12 13 fourteen Color Coordinates, x 0.430 0.455 0.457 0.439 0.429 0.380 0.405 0.458 0.385 0.444 0.405 0.453 0.490 0.147 Color Coordinates, y 0.457 0.490 0.517 0.470 0.435 0.475 0.415 0.491 0.384 0.483 0.454 0.450 0.459 0,041 Illumination, lx 460 490 270 470 430 440 435 480 450 440 348 250 336 106 Color temperature ° K 3550 3350 3400 3550 3350 3550 3650 3260 3800 3350 3950 3250 3850 Not measured The radiation intensity, f _Rel. in the wavelength range of 420-500 nm 0.3 0.125 0.01 0,120 0.22 0.17 0.20 0.16 0.94 0.28 0.37 0.01 0.34 1,0

As can be seen from the information presented, only the obligatory presence of wax, the Ultranox 626 thermal stabilizer and the Tinuvin 360 UV absorber in strictly defined quantities ensure the achievement of the claimed technical result in terms of reducing blue light intensity and increasing illumination, as evidenced by control examples:

- example 10: the replacement of the thermal stabilizer Ultranox 626 with Irgafos 168 in the optimal composition of the composition according to the invention does not lead to the claimed effect;

- example 11: the need for the introduction of wax (comparison with example 2);

- example 12: the correct choice of the upper limit of the photoluminophore (comparison with example 3);

- examples 13 and 14: use in combination with polycarbonate and wax only the declared photoluminophore or photostabilizer (Tinuvin 360) does not affect the change in the intensity of blue light (figure 4 and figure 5, respectively).

The proposed composition is superior to the composition of the prototype in reducing the intensity of blue light emission (0.01-0.3 according to the invention versus 0.94 for the prototype).

The excess values of the chromaticity coordinates x and y according to the invention compared with the prototype indicates the receipt of "warm white light" close to the light of an incandescent lamp (2851 ° K), which is also confirmed by a decrease in the color temperature level (3260-3650 according to the invention versus 3800 according to prototype).

The effectiveness of the proposed compositions in terms of illumination is about 9% (490 lux according to example 2 of the invention against 450 lux according to the prototype).

Moreover, the claimed composition (products based on it) eliminates the toxic effect of blue light and the risk of blinding.

Forming materials for light converting products that do not require the use of protective lenses are obtained from the composition in accordance with the invention. Products of a simple and complex configuration, characterized by high reliability, with a given level of optical characteristics for LED technology, are made by highly efficient casting and extrusion methods.

The effect shown by the composition developed in accordance with the invention in terms of reducing the intensity of blue light could not be assumed, since it is achieved by introducing into the composition of the composition of the known Tinuvin 360 ultraviolet absorber - 2,2-methylene-bis [4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotrizol-2-yl) phenol]. This photostabilizer is widely used for its intended purpose - to slow down the decomposition of the polymer chain under the influence of ultraviolet radiation and is recommended to increase the light resistance of a wide range of polymers - acrylic resins, polyolefins, polyamides, polyacetals, polyalkylene terephthalates, polycarbonates and other high-tech polymers.

Known, for example, the development of Bayer AG., Relating to compositions containing PC (RU 2266933, C08L 69/00, C08K 5/101, publ. 12/27/2005 and RU 2293749, C08L 69/00, C08K 5/3475, publ. . 02.20.2007).

The first of them relates to PC compositions, which make it possible to manufacture products from them without damaging the surface due to the use of two or more linear carboxylic acid esters and branched alcohol in the composition as an external lubricant incompatible with the polymer. The composition is intended for the manufacture of panels, greenhouses, billboards, etc. co-extruding the main PC and PC composition containing a different brand of PC and, as target additives, the Irgafos 168 thermostabilizer and UV absorber, incl. Tinuvin 360 separately or together. But in the examples only Tinuvin 360 was used in an amount of 5%.

The second of these patents relates to compositions containing a thermoplastic and at least two benzotriazole UV absorbers and, if necessary, Irgafos 168 thermal stabilizers. In accordance with the composition, multilayer plates are made by coextrusion of the main PC with compositions based on another brand of PC containing a mixture of 5-10% Tinuvin 360 and 0.1-0.25% Tinuvin 350 (or T329 or T324). The effect is the elimination of surface defects over large areas. Manufactured products: multilayer ribbed plates, monolithic wavy, ribbed profiled products, including with a groove and an insert stud, glass for greenhouses, winter gardens and bus installations, a billboard, etc.

An analysis of the patents discussed above, providing the possibility of using Tinuvin 360 in PC materials, indicates that neither the type of materials and their purpose, nor the means for realizing the claimed effects, nor even the amount of absorber used, have an analogy with our development and, therefore, cannot defame its security.

Claims (1)

A polymer luminescent composition for producing white light, excited by a blue LED, including transparent polycarbonate, aluminum-yttrium-garnet type phosphor phosphor activated by cerium, polyethylene wax in the form of a powder with a particle size of 18-30 μm and a heat stabilizer, characterized in that the composition contains polycarbonate with an indicator as polycarbonate The melt flow of 6-40 g / 10 min, as photoluminescent phosphor - yttrium-gadolinium garnet alyumogallievy, activated with cerium, of formula (YGd) ₃ (AlGa) ₅ O _12: Ce, as thermos abilizatora - Ultranox 626 and Tinuvin 360 in addition with the following ratio of components of the composition, in parts by weight .:
specified polycarbonate one hundred specified photoluminophore 1,5-7 specified wax 0.1-0.7 Ultranox 626 0.2-1.0 Tinuvin 360 0.15-0.3

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