RU2243985C2 - Light-accumulating polymeric layer - Google Patents

Abstract

FIELD: polymer materials.

SUBSTANCE: polymeric layer is made in the form of polydimethylsiloxane or polycarbonate-based film uniformly filled with luminophor mixture in amount 10 to 80%, which mixture contains ZnS·Co·Ni and/or ZnS·CsS·Cu·Co Ni and CeAl₂O₄·Eu·Dy. Weight ratio of zinc sulfide to aluminate luminophor ranges from 1:99 to 10:90. Molecular weights of polydimethylsiloxane and polycarbonate are more than 30000 and 30000-35000, respectively. Luminophor particle size is 10 to 60 mcm. Thickness of polymer film is ranges from 90 to 2000 mcm. In case of polycarbonate polymeric film, informational graphic symbols, marks, and text are applied onto surface of the film by offset print technique and, in case of polydimethylsiloxane film, by explication technique. Polymeric layer may be supported by light-reflecting carrier whose thickness id comparable with that of luminophor grains. Initial brightness and accumulated light are in excess as compared to prior art analogues.

EFFECT: increased strength, elasticity, resistance to mechanical and environmental effects, reduced cost, and prolonged after-excitation emission.

6 cl, 3 tbl

Description

The invention relates to the field of lighting and autonomous emergency lighting. Specifically, the invention relates to the creation of light-accumulating thin-layer light sources emitting autonomously for many hours after the cessation of excitation.

Known polymer layer [1], made in the form of a polymer film with a luminescent filler, which is used as a phosphor that converts the absorbed radiation into radiation of another spectral region. However, this polymer layer does not have the properties of light accumulation and long-term radiation after the cessation of excitation.

Various versions of light-accumulating materials based on inorganic phosphors from zinc-cadmium-copper sulfides, from calcium-samarium sulfides, from alkaline earth metal aluminates of the SrAl ₂ O ₄ · Eu · Dy type [2], [3] are known. Luminous products using these phosphors are made in the form of paints and varnishes based, for example, on various compositions of vinyl chloride resin. These varnishes are used for vertical marking on freeways, with their help they create luminous panels and dioramas, and are used for coloring various attractions.

Despite the known simplicity, cheapness and availability of vinyl varnishes when working with them, significant disadvantages were identified:

- high toxicity due to the presence of a significant amount of free chlorine,

- low hydrolytic stability, especially when exposed to intense solar radiation;

- a temporary change in the transmission spectrum of vinyl chloride varnish, expressed in its intense yellowing.

Closest to the proposed is a polymer layer, which is a compound of an epoxy polymer filled with an inorganic phosphor and including an aluminate phosphor [3]. It can be used to obtain light-accumulating varnishes, putties, decorative coatings. Sufficient survivability of the epoxy resin compound, ease of use and relatively large areas of the luminous surface are noted, which allows it to be used in advertising sheets with a large surface.

However, despite the known advantages, epoxy compounds are not free from significant disadvantages:

- significantly reduced initial brightness of the luminescence of the storage phosphor in epoxy layers compared to a phosphor not introduced into the layer;

- a sharply reduced value of the accumulated light sum of the storage phosphor in epoxy layers compared to a phosphor not introduced into the layer;

- high fragility and brittleness, especially at elevated temperatures, of products from the epoxy compound with light-accumulating phosphor;

- the inability to create on the basis of epoxy compounds flexible luminous coatings of a large area.

The technical result from the use of the proposed technical solution is to create a new polymer layer filled with light-accumulating phosphors, emitting autonomously longer after the cessation of excitation, having a high accumulated light sum, high initial brightness, high strength and flexibility, resistance to mechanical and climatic effects, low cost .

The light-accumulating polymer layer uniformly filled with an inorganic light-emitting emitter is made in the form of a film based on polydimethylsiloxane or polycarbonate. A mixture of finely crystalline inorganic zinc sulfide phosphors from the series ZnS • Cu • Co • Ni and / or ZnS • CdS • Cu • Co • Ni and the aluminate phosphor SrAl ₂ O ₄ • Eu • Dy was used as a light-emitting emitter. Moreover, these zinc-sulfide and aluminate phosphors are introduced into the composition of the film with a mass ratio between them of 1:99 to 10:90, respectively, and the concentration of the mixture of phosphors in the film is from 10 to 80% by mass. The molecular weight of the polymer bases of the light-accumulating layer is more than 30,000 cu for polydimethylsiloxane and from 30000 cu up to 35000 cu for polycarbonate, respectively.

The geometric thickness of the polymer film is from 90 to 2000 microns.

The grain size of the inorganic phosphors filling the layer lies in the range from 10 to 60 microns.

The polymer layer is made on a reflective carrier, the geometric thickness of which is commensurate with the geometric dimensions of the grains of inorganic phosphors dispersed in the light-accumulating polymer layer.

Information or graphic symbols, signs, text, deposited on the surface of a polycarbonate-based film, are made by the method of explication or offset printing. Information or graphic symbols, signs, text, applied to the surface of the film based on polydimethylsiloxane, are made by the method of explication from the material of the film or contrast material. Also mentioned symbols, signs, text can be applied to the surface of the layer by any method of applying dyes.

The total radiation of the proposed phosphor composition has a white color, close in color temperature to the source C with T-6300K, emitted within 0.5-2 hours when the specified film is excited by artificial (fluorescent, incandescent) or natural light for 0.5 -1 minutes. Physicochemical essence of the invention lies in the fact that as svetonakopitelya proposed to use not one but a mixture of two phosphors, the first of which allows to achieve a high value of the initial luminance afterglow (L> 15 cd / m ² at 15 seconds after cessation of excitation) while the second - high accumulated light sum (more than 10 lux-hours), providing a bright glow for 2-4 hours of operation. The indicated advantages of the new proposed material in the speed of light accumulation, the possibility of obtaining an integral white glow, the amount of accumulated light sum in the light-accumulating polymer layer are achieved with a mass ratio between zinc sulfide and aluminate phosphors from 1:99 to 10:90 at a concentration of a mixture of phosphors from 10 to 80% by mass and when using as a basis a film of polydimethylsiloxane or polycarbonate with a molecular weight of more than 30,000 cu or from 30,000 to 35,000 cu respectively.

In the process of working on the invention, various variants of the phosphor-polymer composition were manufactured, the technological and lighting parameters of which are given in table. 1 and table 2.

Table 1 No. p / p Composition Flash Intensity,% Accumulated light sum,% Film thickness, microns Polycarbonate ZnS · Cu · Co · Ni SrAl ₂ O ₄ Eu Dy,% 1 90 1 nine 100 100 240 2 40 3 57 350 420 140 3 60 2 38 240 360 190 4 90 0.1 9.9 120 200 160 Composition Polycarbonate ZnS · CdSCu · Co · Ni SrAl ₂ O ₄ · Eu · Dy,% 5 90 0.1 9.9 130 190 170 6 90 1 nine 110 110 220

Composition Polydimethylsiloxane ZnS · CdS · Cu · Co · Ni SrAl ₂ O ₄ · Eu · Dy,% 7 40 5 55 580 720 200 8 twenty 5 75 1000 1500 500 nine 70 3 27 700 900 350 Composition Polydimethylsiloxane ZnS · Cu · Co · Ni SrAl ₂ O ₄ · Eu · Dy,% 10 90 0.1 9.9 600 650 320 eleven Epoxy Polymer Reference - thirty 80 100 100

table 2 No. Composition Intensity Accumulated Thickness P / P Polydimethylsiloxane ZnS CuCo Ni ZnS · CdS • CuCo · Ni SrAl ₂ O ₄ Eu Eu Dy flash and,% light sum,% films, microns 1 70 2 1 27 190 340 170 2 70 1 2 27 210 340 160 Composition Polycarbonate ZnS CuCo Ni ZnS · CdS · CuCo · Ni SrAl ₂ O ₄ Eu Eu Dy 3 90 0.05 0.05 9.9 120 200 160 4 90 0.1 0.1 9.8 130 190 170

The time from the moment of excitation to the physical threshold of eye sensitivity equal to 0.3 mcd / m ² is for a composition with a maximum value of the accumulated light sum of 70 hours. The excitation energy of the film was 2.4–4.2 eV.

The light-accumulating film based on polydimethylsiloxane has a tensile strength exceeding 20 kg / cm ² . With a degree of luminophore filling up to 10%, the film can withstand 30% stretching. An increase in the mass concentration of the phosphor up to 20% is accompanied by a decrease in the degree of stretching to 22%. A film with 60% filling retains an elongation of 10%. The physicomechanical properties of the film change little with variations in its thickness ranging from 90 to 300 microns. A light-accumulating polycarbonate-based polymer film has higher physical and mechanical parameters compared to polydimethylsiloxane-based films.

We found that the physicomechanical properties, as well as the brightness of the glow of the light-accumulating film, also depend on the particle size of the phosphors. The optimum particle size of phosphors is in the range from 10 to 60 microns. Films with this particle size of phosphors based on polycarbonate and polydimethylsiloxane, respectively, have uniform two-sided emission with maximum brightness. We have verified the dependence of the initial brightness and the accumulated light sum on the particle size of the aluminate phosphor. It was shown that the use of an aluminate phosphor with an average particle diameter of d ₅₀ = 60 μm makes it possible to increase the initial brightness by 50% and the accumulated light sum by 100% in comparison with a phosphor having an average particle diameter of d ₅₀ = 25 μm. If you use larger particles with d ₅₀ = 100 μm, the initial brightness increases by 75%, while the accumulated light sum increases to 145%. The mechanical parameters of the film are reduced. On the other hand, the use of small particles of an aluminate phosphor, for example, up to d ₅₀ ≤ 15 μm, reduces the initial brightness in comparison with a film filled with a phosphor with d ₅₀ = 30 μm by 30%; at the same time, the value of the accumulated light sum is reduced by 55% for this sample. The physicomechanical parameters of a film with small particles of a phosphor substantially increase two or more times. The embodiment of the film on a flexible aluminum carrier, the geometric thickness of which is commensurate with the geometric dimensions of the finely crystalline phosphors filling the film, makes it possible to increase the brightness by 3.2 times compared to a film without a reflector, which indicates the complexity of the physical processes that accompany light accumulation.

The production of light-accumulating film is carried out by manual irrigation (based on polydimethylsiloxane and polycarbonate) or using a watering machine (for a polycarbonate-based film). In the case of manufacturing a film using a flexible aluminum carrier, the latter is bonded to the film using glue.

Information symbols, signs, text are applied to the surface of a polycarbonate film by offset printing. Information symbols, signs and text when using films based on polydimethylsiloxane are performed by explication from the material of the film.

The following is an example of the manufacture of a polycarbonate-based light-emitting polymer film filled with a binary mixture of ZnS · Cu · Co · Ni and SrAl ₂ O ₄ · Eu · Dy phosphors.

The phosphor ZnS · Cu · Co · Ni is made in the following sequence:

- take 96 g of ZnS, 0.100 g of CuNO ₃ , 0.050 g of Co (NO ₃ ) ₃ · 6H ₂ O, 0.050 g of Ni (NO ₃ ) ₂ · 6H ₂ O, 5 g of NaCl;

- mix the components;

- load the mixture into quartz crucibles;

- calcined at a temperature of T = 980 ° C for 1.5 hours.

The phosphor SrAl ₂ O ₄ · Eu · Dy is made in the following sequence:

- take 100 g of SrCO ₃ , 120 g of Al ₂ O ₃ , 0.5 g of Y ₂ O ₃ , 1.1 g of Eu ₂ O ₃ , 1.3 g of Dy ₂ O ₃ , 1 g of H ₃ BO ₃ ;

- mix the components;

- load the mixture into alundum crucibles;

- calcined in a reducing atmosphere N ₂ : H ₂ = 95: 5% vol. At a temperature of T = 1400 ° C;

- the resulting product is crushed in a roller mill and passed through a 500 mesh sieve.

A binary mixture of ZnS · Cu · Co · Ni and SrAl ₂ O ₄ · Eu · Dy phosphors is prepared in a ratio of 30%: 70%, respectively.

Prepare a solution of industrial grades of polycarbonate PK-2 with a molecular weight of 32,000-35,000 cu in methylene chloride in accordance with the recipe:

- polycarbonate PK-2 - 14 parts by weight;

- methylene chloride - 86 parts by weight.

A binary mixture of ZnS · Cu · Co · Ni and SrAl ₂ O ₄ · Eu · Dy phosphors is introduced into the prepared polymer solution with stirring in accordance with the recipe:

- polymer solution - 100 weight parts;

- a binary mixture of phosphors - 45-50% of the mass.

The resulting homogeneous suspension is filtered, evacuated and introduced into the die of the irrigation machine to form the film material of the required thickness - (180-200) microns.

The width and length of the resulting film is 200 mm and 1200 mm, respectively. Information symbols, signs, and text are applied to the resulting film by offset printing. The required number of characters, symbols, and texts are cut from the obtained film. The cost of one character, symbol, text is approximately 60-70 rubles.

Table 3 shows the data on measuring the brightness of the glow depending on the time after the moment of excitation for the proposed polymer light-accumulating layers and the polymer light-accumulating layer of the prototype.

Table 3 No. p / p Light storage layer material The time elapsed from the moment of excitation, min The brightness of the layer, mcd / m ² 1 Prototype Layer Material 5 920 10 350 fifteen 235 2 The material of the proposed layer based on polycarbonate 5 1140 10 700 fifteen 420 3 The material of the proposed layer based on polydimethylsiloxane 5 1585 10 825 fifteen 667

Literature

1. RF patent №2118785, F 41 H 3/00, 1998

2. Handbooc of Phosphors. CKC Press, 1999

3. Hemoto brochure.

4. US Patent No. 5424006, C 09 K 11/80, 1995

Claims (6)

1. A light-accumulating polymer layer uniformly filled with an inorganic light-emitting emitter including an aluminate phosphor, characterized in that the polymer layer is made in the form of a film based on polydimethylsiloxane or polycarbonate, and a mixture of fine crystalline inorganic zinc-sulfide phosphors from the ZnS • series is used as a light-emitting emitter. Co • Ni and / or ZnS • CdS • Cu • Co • Ni and the aluminate phosphor SrAl ₂ O ₄ • Eu • Dy, while these zinc sulfide and aluminate phosphors are introduced into film tav at a mass ratio between them from 1:99 to 10:90, respectively, the concentration of the phosphor mixture in the film is from 10 to 80 wt.%, the molecular weight of the polymer bases of the light-accumulating layer is more than 30,000 cu for polydimethylsiloxane and from 30000 cu up to 35000 cu for polycarbonate, respectively. 2. The light-accumulating polymer layer according to claim 1, characterized in that the geometric thickness of the polymer film is from 90 to 2000 microns. 3. The light-accumulating polymer layer according to claims 1 and 2, characterized in that the particle size of the inorganic phosphors filling the layer lies in the range from 10 to 60 microns. 4. The light-accumulating polymer layer according to claims 1 to 4, characterized in that said polymer layer is made on a reflective carrier, the geometric thickness of which is comparable to the geometric sizes of grains of inorganic phosphors dispersed in the light-accumulating polymer layer. 5. The light-accumulating polymer layer according to claims 1 to 3, characterized in that information or graphic symbols, signs, text are applied to the surface of the polycarbonate film by offset printing. 6. The light-accumulating polymer layer according to claims 1 to 3, characterized in that the information or graphic symbols, signs, and text when using a film based on polydimethylsiloxane are made by explication from the film material.