JP5389823B2 - Pure phosphorescent phosphor ceramics - Google Patents

Description

The present invention relates to an innocuous phosphorescent phosphor ceramic that can be used for evacuation route display boards, auxiliary lighting, signs, tiles, and the like.

In recent years, the demand for phosphorescent phosphors has been increasing as a measure against disasters by displaying evacuation routes in subway premises and high-rise buildings. Phosphorescent phosphors are usually sold as powders, which are usually kneaded into transparent resin or dispersed in paint to be used as structures such as molded bodies and display boards (for example, patents) (Refer to Literatures 1 and 2).

Further, as a special example, a method has been proposed in which phosphorescent phosphor powder is mixed with glass powder (frit) and the glass is melted at several hundred degrees Celsius and used as a composite ceramic structure (Patent Documents 3 and 4). Etc.).

Furthermore, a method has also been proposed in which the phosphorescent phosphor powder itself is molded and sintered to obtain a pure and dense phosphorescent phosphor ceramic (see Patent Documents 5 and 6, etc.).

JP-A-8-129351 JP-A-9-146482 JP 2000-319832 A Japanese Patent Laid-Open No. 10-101371 JP 2005-105116 A, paragraph 0017, etc. JP-A-11-181420, paragraphs 0004, 0010, etc. JP 2007-118203 A

However, these products have a long manufacturing process, and at present, afterglow luminance corresponding to the cost is not obtained although it is expensive.

A product in which phosphorescent phosphor particles are dispersed in an organic material such as a resin is inferior in weather resistance, and when used outdoors, the resin is devitrified or yellowed in a short period of time, and the excitation light is weakened. Furthermore, since organic materials such as resins have some water absorption, rainwater and the like gradually permeate and reach the surface of the phosphorescent phosphor particles, and the phosphor is gradually hydrolyzed to deteriorate phosphorescent performance.
In Patent Document 7, the weather resistance is enhanced by using a silicone resin as the resin material, but this is not semi-permanent, and the deterioration rate is several years slower than that of a normal resin material. belongs to.

In the case of a composite ceramic body in which phosphorescent phosphor particles are melt-dispersed in glass, the weather resistance is not a problem. However, since it melts at a temperature higher than the melting point of the glass, the glass and phosphorescent phosphor particles react to store the phosphor. It has a problem that performance deteriorates.

In addition, products with phosphorescent phosphor particles dispersed in a medium such as resin or glass are prone to scattering loss of excitation light on the surface of the particles and have strong concealment, so phosphors in the deep part of several hundred microns or more are not excited. It is wasted and sufficient afterglow cannot be obtained.

In contrast, innocent phosphorescent phosphor ceramics made by sintering phosphorescent phosphor particles themselves have very high weather resistance compared to the above-mentioned medium-dispersed products, and the particles are sintered together. As a result, it becomes a densely connected structure and scattering loss hardly occurs, so that the afterglow brightness is also improved.

However, even in such a case, the depth at which the excitation light can penetrate is up to several millimeters, and the excitation light cannot effectively reach a depth of several millimeters or more because of the strong excitation light absorption of the phosphor itself. This is the same even for a transparent and dense sintered body, and since the phosphor in the deep part is not effectively used, sufficient afterglow luminance cannot be obtained.
The present invention has been made in view of the above situation, and an object of the present invention is to obtain a phosphorescent phosphor ceramic that can effectively utilize a phosphor in a deep part.

In order to solve the above problems, the present inventors diligently studied to improve the luminance. As a result, the light receiving area was increased on the surface of the solid phosphor phosphor, and the afterglow in the direction perpendicular to the light irradiation surface. It was discovered that when a concave structure that enhances radiation is formed, the total amount of stored phosphorous energy increases, and the afterglow luminance is several times that of conventional phosphorescent phosphor ceramic products, leading to the present invention.

The gist of the present invention is a solid phosphor fluorescent ceramic having a concave portion on the light irradiation surface, the total area of the surface area inside the concave portion and the surface area of the convex surface (top surface) defining the concave portion. Is a solid phosphor fluorescent ceramic that is larger than the projected area of the light-irradiated surface and has the recesses formed so as to increase the afterglow luminance measured from a direction perpendicular to the light-irradiated surface.

According to the present invention, since it is in the sintered body, there is no scattering loss of the excitation light by the particles, the surface area directly exposed to the excitation light is increased, and several times that of the conventional phosphorescent product in the direction perpendicular to the light irradiation surface. A phosphorescent phosphor ceramic sintered body exhibiting afterglow luminance can be obtained, which is so weatherable that it can be used semi-permanently outdoors, and its utility value is extremely high.

It is the typical perspective view (a) of the one aspect | mode of the luminous phosphor ceramic concerning this invention, and its BB sectional drawing (b). Schematic perspective views (a), (c) and (e) of phosphorescent phosphor ceramics according to the present invention in which recesses having various opening shapes are formed, and BB cross-sectional views (b) and D- It is D sectional drawing (d) and FF sectional drawing (f). It is the typical perspective view (a) of the one aspect | mode of the luminous phosphor ceramic concerning this invention, and its BB sectional drawing (b). It is the typical perspective view (a) of the one aspect | mode of the luminous phosphor ceramic concerning this invention, and its BB sectional drawing (b). It is a dimension figure for calculating the area inside the crevice provided in luminous phosphor ceramic concerning the present invention.

DESCRIPTION OF SYMBOLS 1 Phosphorescent ceramics 2 Recessed opening surface outer periphery 3 Recessed opening surface 4 Recessed bottom surface outer periphery 5 Recessed surface 6 Recessed bottom surface outer periphery and bottom surface outer periphery with a minimum distance 7 Recessed bottom surface 8 Perpendicular to opening surface 9 Recessed inner wall surface 12 Edge

Hereinafter, the present invention will be described in detail.
The phosphorescent phosphor ceramics of the present invention are used for products such as evacuation route display boards, auxiliary lighting, signs, tiles and the like.

The phosphorescent phosphor ceramic according to the present invention is an innocent phosphorescent phosphor ceramic provided with a concave portion on a light (visible light) irradiation surface, and the concave portion increases a light receiving area as compared with a case where the concave portion is not formed, and A solid phosphor fluorescent ceramic formed so as to increase the afterglow luminance measured from a direction perpendicular to the light irradiation surface.
When the concave portion is formed on the surface of the phosphorescent structure, the surface area to which the excitation light hits increases even if the appearance from the direction perpendicular to the opening surface is the same area. As a result, the total amount of phosphorescent phosphors to be excited increases, and the amount of afterglow generated increases. Furthermore, by devising the structure of the recess, the amount of emission in the direction perpendicular to the light irradiation surface can be increased.
Furthermore, if the material of the phosphorescent structure is a solid phosphor phosphor ceramic, there will be no scattering loss of excitation light due to particles, so the total amount of phosphor phosphor excited in the depth direction will increase. The afterglow brightness becomes stronger.
In the present specification, the phrase “solid phosphor” is “innocent” means that it is substantially composed of phosphor phosphor composition components. “Substantially only phosphorescent phosphor composition component” means that, in addition to the phosphorescent phosphor composition component, a flux component that is a reaction accelerator that may be added in a small amount during the synthesis of the phosphor may be included as an optional component. .
Therefore, the phosphorescent phosphor ceramic according to the present invention contains 80 mol% to 100 mol%, preferably 90 to 100 mol%, of the phosphor component in the total composition, and the flux component as an optional component is 0 to 20 in the total composition. It can contain mol%, preferably 0 to 10 mol%.

The size of the recess is not particularly limited as long as it can increase the light receiving area as compared to the case where it is not formed and can increase the afterglow luminance measured from the direction perpendicular to the light irradiation surface. as, when the area of the light irradiation surface of the ceramic, the geometric area of the total surface area and the convex portion flat in the recess in particular S, projected area of the surface (= the area of the planar portion) was set to S _a, It can be expressed by (S / S _a ) (that is, the rate of increase in surface area due to unevenness). S _a means an area when the surface has no irregularities and is completely smooth. The increased surface area S does not include an increase due to unintended surface roughness. This “roughness” is not limited, but roughly speaking, means a rough surface having a maximum roughness (H _max ) of less than 1 mm as measured by a roughness meter. (S / S _a ) is greater than 1.0, preferably 1.2 or more and less than 10, more preferably 1.5 or more and less than 8. If the unevenness is small, the effect is thin, and if it is 10 or more, the formation cost may be high instead of the effect.
The surface area increase rate (S / S _a ) due to the unevenness is a value obtained by measuring the three-dimensional image size of the recess using a microscope or the like and performing arithmetic processing using a computer or the like. As a specific example, for example, when the concave shape is an inverted conical shape and an inverted conical column shape, (S / S _a ) is an angle value (θ) obtained with a three-dimensional measuring machine as shown in FIG. Based on the obtained opening diameter value (D1) and the depth value (L2) obtained by the depth meter, the bottom area of the recess and the side area of the conical column can be calculated and calculated by the following formula.
d1 = D1 / 2 / SINθ
D2 = D1-2 * TANθ * L2
d2 = D2 / 2 / SINθ
S / S _a = [Sa-π * (D1 / 2) ² * hole number + {π * (D1 / 2 * d1-D2 / 2 * d2) + π * (D2 / 2) ² } * hole number] / S _a

Furthermore, it is preferable that the said recessed part has a bottom face, and the shape of an opening surface, the shape of a recessed part bottom face, and the shape of a recessed cross section parallel to the said opening surface are mutually congruent shape or a similar shape.
Although it does not specifically limit as a shape of an opening surface, It is preferable that it is circular or a polygon (square, hexagon).
FIG. 1 shows a schematic perspective view of one aspect of the phosphorescent phosphor ceramic 1. In FIG. 1, the shape of the opening surface 3 is circular on the ceramic surface, and the bottom surface 7 is also formed with a recess 5 having a circular shape with the same diameter as the opening surface in a direction perpendicular to the surface.
The shape of the opening surface, the shape of the bottom surface of the recess, and the shape of the cross section of the recess parallel to the opening surface are not congruent or similar to each other, for example, undulations with irregular cross-sectional shapes, as shown in FIG. Even in the case of the corrugated concave portion having no bottom surface, the amount of afterglow generated itself increases, but in a direction other than the direction perpendicular to the opening surface 3 when reflected by the inner wall surface (side surface) 9 of the concave portion. There is much afterglow to escape, and the effect may be slightly reduced.

In order to increase the afterglow luminance, it is preferable that not only the bottom surface 7 of the recess 5 but also the inner wall (side surface) 9 of the recess 5 are luminous. FIG. 2 is a sectional view of a recess having various opening surface shapes. The angle formed by the straight line 6 connecting the outer periphery 2 of the opening 5 and the outer periphery 4 of the recess 5 with a minimum distance and the perpendicular 8 to the opening 3 of the recess is preferably in the range of −15 ° to less than 45 °. As shown in FIGS. 2 (c) and 2 (d), if the angle is less than −15 °, the efficiency of taking afterglow from the recess in the direction 8 perpendicular to the bottom surface 7 of the recess may be deteriorated. As shown in f), when the angle is 45 ° or more, there is a lot of afterglow that escapes in a direction other than the direction 8 perpendicular to the bottom surface 7 of the recess, and the effect may be reduced. As described above, the present invention forms the concave portion so as to increase the afterglow luminance in the direction perpendicular to the light irradiation surface. Therefore, the present invention simply teaches or suggests a structure for expanding the light receiving area, for example, This is significantly different from the concave structure found in the photocatalyst field.

The circle-equivalent diameter of the concave opening surface 3 is preferably 0.1 mm or more and 100 mm or less. If it is less than 0.1 mm, the formation of the recess 5 may be difficult, and if it exceeds 100 mm, the effect of increasing the surface area may be reduced.

The depth of the recess 5 is preferably 0.3 to 4 times the circle-converted diameter of the recess opening surface 3, and more preferably 0.3 to 3 times. If the ratio is less than 0.3 times, the effect of surface area increase is low and the effect may be reduced. If the ratio exceeds 4 times, the area increases, but the number of times the excitation light or afterglow is reflected on the inner wall surface (side surface). May increase, and the effect may reach its peak.

FIG. 4 shows a phosphorescent phosphor ceramic 1 in which a concave portion 5 in which the shape of the opening surface 3 is square is formed on the light irradiation surface. As is clear from FIG. 4, it is preferable that the surface of the phosphorescent phosphor ceramic has a large number of recesses 5 with a constant interval length L.
The interval length L between adjacent recesses is preferably 0.1 mm to 10 mm. If it is less than 0.1 mm, the strength of the inner wall surface 9 may be weakened, and if it exceeds 10 mm, the effect of increasing the excitation area may be reduced.
The area ratio (S1 / S2) is 0.1, where S1 is the area of the edge 12 other than the aperture 3 and the area of the aperture 3 is S2 in the projected area (Sa) of the light-irradiated surface of the phosphor phosphor. 10 to 10 is preferable. If it is less than 0.1, the strength of the inner wall surface 9 may be weakened, and if it exceeds 10, the effect of increasing the excitation area may be reduced.

In addition, as the phosphorescent phosphor used in the phosphorescent phosphor ceramic of the present invention, a commercially available product using zinc sulfide or an alkaline earth metal aluminate as a crystal matrix is popular. All long-lasting phosphors that can be made of ceramics made of phosphorescent phosphors are applicable.
As such a phosphorescent phosphor, M is at least one element of Sr, Ca, Ba, and Mg, and MAl ₂ O ₄ : Eu, Dy, M ₄ Al ₁₄ O ₂₅ : Eu, Dy, Sr ₃ MgSi _2. Specific examples include O ₈ : Eu, Dy, Cl, Y ₂ O ₂ S: Eu, Mg, Ti, ZnS: Cu, (Ca, Sr) S: Bi, (Zn, Cd) S: Cu type. However, it is not limited to these.
At present, alkaline earth metal aluminates with rare earth elements having the highest afterglow brightness and excellent weather resistance are practical and preferred. Alkaline earth metal aluminates are exemplified in Japanese Patent Nos. 2543825 and 3323548, but in these documents, only fluorescence in powder is used.

The phosphorescent phosphor ceramic of the present invention can also be produced by molding and sintering phosphorescent phosphor particles, but more preferably, the phosphor powder raw material powder mixture is molded so as to have a desired concave shape and fluorescent. It is advisable to carry out the soaking reaction and sintering at the same time. Existing phosphorescent phosphor particles generally have poor moldability and sinterability, and the manufacturing cost increases because the pressure during molding and the temperature required for sintering are high. On the other hand, by using a raw material powder mixture as a solid phosphor, sintering proceeds easily when a phosphorescent phosphor composition is produced by a chemical reaction during firing, so a relatively low molding pressure (0. ^{1kg / cm 2 ~500kg / cm 2} ) and a relatively low sintering temperature (800 ° C. to 1500 ° C., preferably can be obtained a ceramic at 1000 ° C. to 1400 ° C.).
Sintering can be performed in a non-oxidizing gas such as argon, nitrogen, carbon monoxide, or a weakly reducing gas atmosphere such as nitrogen containing hydrogen.
The average particle size of each substance of the main raw material powder of the phosphorescent phosphor is preferably 0.1 μm to 10 μm. The average particle diameter is a value that can be measured by a laser diffraction method.

The method for forming the recesses in the phosphorescent phosphor ceramic of the present invention is not particularly limited, but the time when the molded body is formed by molding with an uneven mold or by machining such as grinding or recess forming on the surface of the flat molded body Apply processing. The formation of the recess can be performed by drilling or the like after the flat molded body is sintered, and does not exclude such a forming method. It is also possible to combine the planar structures three-dimensionally.

The phosphorescent phosphor ceramics of the present invention may be coated with a transparent resin on the surface or baked and coated with a transparent glass frit for the purpose of surface protection or design.

Examples of the present invention will be described below, but the present invention is not limited thereto.
(Example 1) (Comparative Example 1) <Concavity formation processing of planar structure>
640 g of alumina (average particle size: 1.2 μm), 890 g of Sr carbonate (average particle size: 2.2 μm), 22 g of oxidized Dy (average particle size: 5.7 μm), and 11 g of Eu oxide (average particle size: 6.5 μm) And 30 g of boric acid (average particle size: 500 μm) were mixed by a ball mill for 6 hours to obtain a raw material powder mixture.
150 g of this was molded into a flat plate shape (100 * 100 * 10 t) with a press pressure of 100 kg / cm ² using a 100 mm square mold. Two flat molded bodies were prepared, and 81 cylindrical recesses having a diameter of 5 mm and a depth of 5 mm were formed on one upper surface portion by grinding at intervals of 5 mm. Both were placed on an alumina plate and sintered at 1300 ° C. for 3 hours (in a nitrogen atmosphere) to obtain a solid phosphorescent phosphor ceramic.
The size of the ceramic was 71 * 71 * 7t by sintering, and the recess hole diameter of the uneven sample was an average of 3.6 mm and the depth was an average of 3.7 mm. Therefore, (S / Sa) = (71 * 71 + 3.6 * 3.14 * 3.7 * 81) / (71 * 71) = 1.67.
After irradiating 5000 Lx D65 standard light for 10 minutes on both upper surface parts and stopping irradiation after 60 minutes, the afterglow brightness | luminance was measured from the direction perpendicular | vertical to the light irradiation surface with a luminance meter (LS-100 by Konica Minolta). , those recesses formed machining the 430mCd / cm ^2, compared with 220mCd / cm ² of flat plate samples showed afterglow luminance about twice.
Comparative Example 1 is a solid phosphor fluorescent ceramic that does not grind Example 1.

(Examples 2-7, Example 13) Solid phosphorescent phosphor ceramics were obtained in the same manner as in Example 1 except that the shape and dimensions of the recesses were changed. The outer dimensions of the ceramics were all 71 * 71 * 7t, and the other dimensions and afterglow luminance were as shown in Table 1. (Dimensions are average values after sintering)
(Examples 8 to 11) Solid phosphorescent phosphor ceramics were obtained in the same manner as in Example 1 except that the shape, size, and hole spacing of the recesses were changed. 400 concave portions were formed. (Example 11 had 81 pieces) The outer dimensions of the ceramics were all 71 * 71 * 7t, and the other dimensional shapes and afterglow luminances were as shown in Table 1. (Dimensions are average values after sintering)
(Example 12, Comparative Example 2) <When the phosphorescent phosphor powder is sintered>
120 g of commercially available phosphorescent phosphor powder (trade name: GLL300F SrAl2O4: Eu, Dy) manufactured by Nemoto Special Chemical Co., Ltd. was press-molded into a flat plate shape at a pressure of 1 t / cm ² using a 76 mm square mold. Two flat molded bodies were prepared, and 81 cylindrical recesses having a diameter of 3.9 mm and a depth of 3.9 mm were formed on one upper surface portion by grinding at intervals of 3.9 mm. Both were placed on an alumina plate and sintered at 1450 ° C. for 3 hours (in a nitrogen atmosphere) to obtain a solid phosphorescent phosphor ceramic. The outer dimensions of the ceramics were 70 * 70 * 7t by sintering, and the concave and convex diameters of the concave and convex samples were an average of 3.7 mm and the depth was an average of 3.6 mm. When the afterglow brightness was measured in the same manner as in Example 1, the recess-formed product showed 340 mCd / cm ² , which was about twice as long as the afterglow brightness of 180 mCd / cm ² of the flat plate sample.
In Comparative Example 2, phosphorescent phosphor ceramics that were not ground in Example 12 were used.

(Comparative Examples 3 and 4) <When phosphorescent phosphor powder is dispersed in glass>
47 g of commercially available phosphorescent phosphor powder (trade name: GLL300F, supra) manufactured by Nemoto Special Chemical Co., Ltd. was mixed with 47 g of lead-free glass frit, and water was added so as to form a hard paste. The obtained paste was molded into a flat plate shape using a 78 mm square mold and dried. Two flat molded bodies were prepared, and 81 cylindrical concave portions having a diameter of 4.0 mm and a depth of 4.0 mm were formed on one upper surface portion by grinding at intervals of 4.0 mm. Both were placed on an alumina plate coated with alumina powder and fired at 700 ° C. for 60 minutes (in a nitrogen atmosphere) to obtain a glass composite amorphous phosphorescent ceramic. The dimensions of the ceramic were 70 * 70 * 7t by firing, and the concave hole diameter of the concave and convex samples was an average of 3.6 mm and the depth was an average of 3.6 mm. When the afterglow brightness was measured in the same manner as in Example 1, 110 mCd / cm ² (Comparative Example 4) and 110 mCd / cm ² (Comparative Example 3) of the flat plate sample were slightly formed. Although an increase was observed, the afterglow increasing effect due to the formation of the recess was very low as compared with the phosphorescent phosphor ceramic of Example 12 having a pure crystal structure. This is probably because the phosphorescent phosphor is present in the form of dispersed particles, and the loss due to scattering or the like is large in the reflection of excitation light and afterglow occurring on the inner surface of the recess. In addition, the comparative example 3 is the luminous body which was not ground in the comparative example 4.

(Comparative Examples 5 and 6) <When phosphorescent phosphor powder is dispersed in resin>
Commercially available phosphorescent phosphor powder (manufactured by Nemoto Special Chemical Co., Ltd., product name: GLL300F, supra) 25 g of transparent silicone resin (manufactured by Shin-Etsu Chemical Co., Ltd., product name: KE-109A, B (1: 1) mixture) 50 g Then, 50 g of the mixture was cast into a 70 mm square mold and heat-cured at 80 ° C. for 1 hour. Two flat molded bodies were prepared, and the outer dimensions were 70 * 70 * 7t. Then, 81 cylindrical recesses having a diameter of 3.6 mm and a depth of 3.7 mm were formed on one upper surface portion by grinding at intervals of 3.6 mm.
Comparative Example 5 is a phosphorescent phosphor when the grinding process in Comparative Example 6 is not performed.
When the afterglow brightness was measured in the same manner as in Example 1, it was 140 mCd / cm ² (Comparative Example 6) that was processed to form a recess, and a little compared with 120 mCd / cm ² (Comparative Example 5) of the flat plate sample. Although an increase was observed, the afterglow increasing effect due to the formation of the recess was very low compared with the solid phosphorescent ceramics such as Example 12. This is probably because the phosphorescent phosphor is present in the form of dispersed particles, and the loss due to scattering or the like is large in the reflection of excitation light and afterglow occurring on the inner surface of the recess.

Claims (7)

It is a solid phosphor fluorescent ceramic with a concave on the light irradiation surface,
Solid phosphorescent phosphor ceramic that is formed so as to increase the light receiving area and increase the afterglow luminance measured from the direction perpendicular to the light irradiation surface as compared with the case where the recess is not formed.   The concave portion has a bottom surface, and the shape of the opening surface of the concave portion, the shape of the bottom surface, and the shape of the concave section parallel to the opening surface are congruent or similar to each other. 1. Solid phosphorescent phosphor ceramics according to 1.   The angle formed by a straight line connecting the outer periphery of the opening surface and the outer periphery of the bottom surface of the recess at a minimum distance and a perpendicular to the opening surface of the recess is in a range of -15 ° to less than 45 °. Solid phosphorescent phosphor ceramic described in 1.   4. The shortest distance from the opening surface of the concave portion to the deepest position of the concave portion is 0.3 to 4 times the circle equivalent diameter of the concave opening surface. Solid phosphorescent phosphor ceramic described in 1.   The solid phosphor phosphor ceramic according to claim 4, wherein the shortest distance from the opening surface of the recess to the deepest position of the recess is 0.3 to 3 times. The solid phosphor phosphor ceramic according to any one of claims 1 to 5, wherein the concave portion is formed by molding with a mold having concaves and convexes, or by machining or the like on the surface of a flat surface forming body. A method for producing a solid phosphorescent phosphor ceramic according to any one of claims 1 to 6,
A method for producing an innocent phosphorescent phosphor ceramic, comprising forming a phosphor powder raw material powder mixture so as to form a recess on a surface to be irradiated with light, and simultaneously performing reaction and sintering.

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