Phosphorescent material and its manufacturing method

Abstract

To provide a phosphorescent material having higher afterglow brightness.SOLUTION: A phosphorescent material made of particles of Sr-Al-R-O based composite oxide (in which, R represents at least one kind of rare earth elements), (1) a median diameter (D50) of the particles is 120 μm or larger, and the particles of particle size 100 μm or less are 40% or less based on the number standard, (2) a shape of the particles is substantially spherical free from corners, (3) phosphorescent intensity due to excitation of a He-Cd laser 325 nm light source is 1×103Cd / m2 or more, and the afterglow brightness when 30 minutes passed by turning off the light source after irradiating 5 minute by the light source is 1×10-2Cd / m2 or more.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a novel luminous material and a method for producing the same. [Background technology]

[0002] Luminescent materials are materials that can absorb light energy from sunlight, electric lights (LED lights), etc., and emit light for a certain period of time in the dark. They have traditionally been used as display materials for clock faces, various instrument panels, etc. Recently, the advantages of luminescent materials, such as the fact that they do not require a power source and are maintenance-free, have been reevaluated, and efforts are being made to expand their applications to a variety of uses. For example, they are being used in various signs (emergency stairs, evacuation area signs), automobile parts, building materials, medical applications (contrast agents), etc.

[0003] Substances that have been used as phosphorescent materials to date include zinc sulfide (ZnS) and strontium aluminate (SrAl2O4), and materials have been developed that use these substances as their basic composition and further add other additives (activators).

[0004] For example, in a compound represented by MAl2O4, the metal element represented by M is a compound consisting of strontium (Sr), magnesium (Mg), and barium (Ba) as a host crystal, and the phosphorescent phosphor contains europium (Eu) as an activator and dysprosium (Dy) as a co-activator, and the content of europium (Eu) is 0.001 or less in molar ratio. A phosphorescent phosphor has been proposed which is characterized in that the molar ratio of Mg / (M+Eu+Dy)≦0.05, the molar ratio of the dysprosium (Dy) content is 0.004≦Dy / (M+Eu+Dy)≦0.06, the molar ratio of Mg (Mg) content is 0.02≦Mg / (M+Eu+Dy)≦0.1, and the molar ratio of barium (Ba) content is 0.03≦Ba / (M+Eu+Dy)≦0.15, and which contains at least one alkali metal element selected from the group consisting of lithium (Li), sodium (Na), potassium (K), and rubidium (Rb), and the content of the alkali metal element is more than 0 and less than 0.06 millimoles per mole of the total of the metal element represented by M, europium (Eu), and dysprosium (Dy) (Patent Document 1).

[0005] Furthermore, for example, there is a phosphorescent material having a compound represented by SrAl2O4 as a host crystal and doped with europium, dysprosium, lithium, and boron, wherein the value obtained by dividing the number of moles of europium by the total number of moles of strontium, europium, dysprosium, and lithium is more than 0.001 and less than 0.025, and the value obtained by dividing the number of moles of dysprosium by the total number of moles of strontium, europium, dysprosium, and lithium is more than 0.001 and less than 0.025, and aluminum A phosphorescent material is known in which the value obtained by dividing the number of moles of boron by the total number of moles of strontium, europium, dysprosium, and lithium is greater than 1.88 and 2.10 or less, the value obtained by dividing the number of moles of lithium by the total number of moles of strontium, europium, dysprosium, and lithium is greater than 0 and less than 0.02, and the value obtained by dividing the number of moles of boron by the total number of moles of strontium, europium, dysprosium, and lithium is greater than 0 and less than 0.03 (Patent Document 2).

[0006] For example, a red-emitting long-lasting phosphor is known, which is a compound represented by MSi2O2N2:Yb,R, where M is at least one metal element selected from strontium (Sr), calcium (Ca), barium (Ba), and magnesium (Mg), and R is at least one element selected from erbium (Er), holmium (Ho), gadolinium (Gd), praseodymium (Pr), terbium (Tb), dysprosium (Dy), neodymium (Nd), bismuth (Bi), scandium (Sc), and chromium (Cr) (Patent Document 3).

[0007] In addition, for example, a spherical phosphorescent microparticle powder of strontium aluminate system using europium and dysprosium as activators has been proposed, characterized in that the powder contains 65% or more particles by number with an aspect ratio of 1.05 or less and has an average particle size D50 of 20 μm or more and 500 μm or less (Patent Document 4). [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Patent Publication No. 2015-214702 [Patent Document 2] Patent Publication No. 2020-23675 [Patent Document 3] International Publication WO2017 / 90541 [Patent Document 4] Patent Publication No. 2020-158624 Summary of the Invention [Problem to be solved by the invention]

[0009] However, these conventional phosphorescent materials need further improvement in terms of luminescence properties. More specifically, the afterglow luminance of the conventional materials is still low, and it is necessary to further improve the afterglow luminance in order to further expand their applications.

[0010] Therefore, a main object of the present invention is to provide a phosphorescent material with higher afterglow brightness. [Means for solving the problem]

[0011] The present inventors have conducted extensive research in light of the problems of the prior art and have found that a material having a specific composition and structure can achieve the above object, thereby completing the present invention.

[0012] That is, the present invention relates to the following phosphorescent material and manufacturing method thereof. 1. A luminous material consisting of particles of Sr-Al-RO based composite oxide (where R represents at least one rare earth element), (1) The median diameter (D50) of the particles is 120 μm or more, and particles having a particle size of 100 μm or less account for 40% or less by number, (2) The particle has a substantially spherical shape without corners, (3) The phosphorescence intensity when excited by a 325 nm He-Cd laser light source is 1×10 3 Cd / m 2 or more, and the afterglow brightness when the light source is turned off after 5 minutes of irradiation and 30 minutes have passed is 1×10 -2 Cd / m 2 That's all. A luminescent material characterized by: 2. When irradiated with a 325 nm He-Cd laser light source, the phosphorescence intensity peaks shown in (1) and (2) below are observed: (1) Yellow-green phosphorescence intensity peak in the wavelength range of 460 to 600 nm (2) Two phosphorescence intensity peaks (a) and (b) below: (a) Blue-green phosphorescence intensity peak within the wavelength range of 420 to 550 nm (b) Phosphorescence intensity peak in the wavelength range of 380 to 450 nm in the purple to blue-violet region Item 2. The luminous material according to item 1, comprising at least one of the following: 3. The luminous material according to item 1 or 2, wherein R includes at least one of europium and dysprosium. 4. The luminous material according to any one of items 1 to 3, wherein the molar ratio of (Sr+R):Al is 1:2 to 4:14. 5. Apparent bulk density 0.5~1.6g / cm 3 5. The luminous material according to any one of items 1 to 4, 6. A method for producing a luminous material consisting of cornerless, approximately spherical particles of Sr-Al-RO based composite oxide (where R represents at least one rare earth element), comprising: (1) preparing a mixed solution containing a Sr raw material, an Al raw material, and an R raw material; (2) granulating the mixture to prepare a granular precursor having a median diameter (D50) of 120 μm or more; (3) heat-treating the granular precursor at 1200 to 1500°C in a non-oxidizing atmosphere A method for producing a phosphorescent material, comprising: 7. The manufacturing method according to item 6, further comprising a step of crushing the heat-treated product in step (3). [Effects of the Invention]

[0013] According to the present invention, it is possible to provide a phosphorescent material with higher afterglow brightness. In particular, the phosphorescent material of the present invention has a specific composition as well as a specific particle size and shape, and therefore can exhibit higher afterglow brightness than existing phosphorescent materials. The reason why high afterglow brightness can be achieved is unclear, but it is thought that this is because the phosphorescent material of the present invention has fewer fine particles that do not contribute to luminescence, thereby increasing the amount of luminescence per unit amount. Furthermore, while cracks, scratches, etc. on the surface of particles are thought to be causes of reduced luminescence properties, the phosphorescent material of the present invention has a relatively smooth particle surface, and there are fewer causes of reduced luminescence properties, which is also thought to contribute to the afterglow intensity.

[0014] Furthermore, in the manufacturing method of the present invention, the material after heat treatment can be used without being crushed, or at most, crushing is required to the extent that agglomerations are broken down, and the crushing step required in the manufacture of conventional luminescent materials is not required, so that the luminescent material can be manufactured at relatively low cost.

[0015] Furthermore, the manufacturing method of the present invention can avoid the inclusion of fine particles that occur during the pulverization process, making it possible to more reliably manufacture a phosphorescent material with excellent luminescent properties.

[0016] The luminous material of the present invention having such characteristics can be widely used for, for example, various signs (signboards, road surfaces, etc.), building materials, stationery, instrument panels, etc. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 2 shows the results of observing the samples obtained in Examples 2 and 7 and Comparative Example 2 with a scanning electron microscope (SEM). DETAILED DESCRIPTION OF THE INVENTION

[0018] 1. Luminous materials The luminous material of the present invention (the material of the present invention) is a luminous material comprising particles of an Sr-Al-RO based composite oxide (where R represents at least one rare earth element), (1) The median diameter (D50) of the particles is 120 μm or more, and particles having a particle size of 100 μm or less account for 40% or less by number, (2) The particle has a substantially spherical shape without corners, (3) The phosphorescence intensity when excited by a 325 nm He-Cd laser light source is 1×10 3 Cd / m 2 or more, and the afterglow brightness after 30 minutes has elapsed since the light source was turned off after 5 minutes of irradiation is 1 x 10 -2 Cd / m 2 That's all. It is characterized by:

[0019] (a) Composition The composition of the material of the present invention is a Sr-Al-R-O system (where R represents at least one rare earth element), and it is composed of a composite oxide containing Sr, Al, and R. As described above, R may be at least one rare earth element, but at least one of dysprosium (Dy) and europium (Eu) is particularly preferable. In this case, it is more preferable to use both dysprosium (Dy) and europium (Eu) in combination. When Dy and Eu are used in combination, the ratio between them can be appropriately set according to the desired composite oxide or the like. For example, the molar ratio Eu:Dy can be about 1:0.2 to 1, but it is not limited to this.

[0020] The composition of the material of the present invention is not limited as long as it is a Sr-Al-R-O system, but it is preferable that the molar ratio (Sr + R):Al is within the range of 1:2 to 4:14. Representative compositions within such a range include Sr 1-n R n Al2O4 (where 0 < n < 1), Sr 4-n R n Al 14 O 25 (where 0 < n < 4), etc. However, as long as the effects of the present invention are not hindered, other compositions containing Sr, Al, and R may also be used.

[0021] In particular, from the perspective of luminescence characteristics, the material of the present invention preferably has the above-mentioned Sr 1-n R n Al2O4 (where 0 < n < 1) (hereinafter also referred to as "Composition A") and / or Sr 4-n R n Al 14 O 25 (where 0 < n < 4) (hereinafter also referred to as "Composition B").

[0022] <� Also, the material of the present invention is preferably crystalline, but an amorphous phase may be included as long as the effects of the present invention are not hindered.

[0023] Composition A is preferably a crystalline material having a monoclinic system, space group P1211, and a phosphorescence wavelength peak top around 515 nm (eg, a wavelength of about 460 to 600 nm associated with yellow-green) when excited by a 325 nm laser light source.

[0024] In the case of composition B, it is preferable that the material be a crystalline material having an orthorhombic system, a space group Pmma, and having a phosphorescence wavelength peak top around 490 nm (e.g., a wavelength of approximately 420 to 550 nm corresponding to blue-green) when excited by a 325 nm laser light source, and also having another peak around 400 nm (e.g., a wavelength of approximately 380 to 450 nm corresponding to the purple to blue-purple region).

[0025] The material of the present invention may be a mixture of a crystalline material of composition A and a crystalline material of composition B, or may contain each of the crystalline materials alone. Furthermore, other crystalline phases may be contained as long as the effects of the present invention are not impaired.

[0026] The content ratio of the R element (when two or more R elements are contained, the ratio of their total amount) is not limited, but is preferably a molar ratio of Sr:R=1:0.001 to 0.1, and more preferably a molar ratio of Sr:R=1:0.005 to 0.05, which allows for better light-emitting properties to be obtained.

[0027] In addition to the above components, the material of the present invention may contain other components within the range that does not impair the effects of the present invention, such as alkali metals (Na, K, etc.), alkaline earth metals other than Sr (Ca, Mg, Ba, etc.), boron (B), sulfur (S), etc.

[0028] (b) Properties etc. The material of the present invention is composed of particles of the material of the present invention, and therefore has the appearance of a dry powder.

[0029] The particle shape is roughly spherical without corners, which can be clearly distinguished from pulverized products with corners. Because of the roughly spherical shape without corners, the particles not only have high brightness but also exhibit excellent performance in terms of, for example, flowability and packing ability.

[0030] The median diameter (D50) of the material of the present invention is usually 120 μm or more, preferably 125 μm or more. If the median diameter is less than 120 μm, the desired afterglow brightness may not be obtained. The upper limit of the median diameter is not particularly limited, but is usually set to about 250 μm. Therefore, for example, the median diameter can be set within the range of 120 to 200 μm.

[0031] The material of the present invention is also characterized by having the above median diameter and having 40% or less (preferably 10% or less) of particles with a particle size of 100 μm or less by number. In other words, the material of the present invention is characterized by a low content of fine powder. This increases the concentration of particles that can contribute to improving brightness per unit amount, thereby achieving higher brightness. The lower limit of the number-based proportion of particles with a particle size of 100 μm or less is not limited, but is usually preferably about 1%, and most preferably 0%.

[0032] Furthermore, it is preferable that the material of the present invention contains few or no coarse particles. More specifically, it is preferable that the number of particles having a particle size exceeding 350 μm is 5% or less, and more preferably 0 to 1%. This allows for higher luminescence intensity (and therefore afterglow brightness) to be obtained.

[0033] The apparent bulk density of the material of the present invention is not limited, but is usually 0.5 to 1.6 g / cm 3 By setting the value within this range, it is possible to exhibit higher light-emitting properties.

[0034] Furthermore, since the material of the present invention is in the form of a dry powder and has a substantially spherical particle shape without corners, it has a certain degree of fluidity. More specifically, it is desirable that the angle of repose (at 20°C) is about 30 to 43 degrees (particularly 32 to 40 degrees).

[0035] There are no particular limitations on the surface treatment of the particles constituting the material of the present invention. If necessary depending on the application, the particles may be made hydrophobic or hydrophilic using silica, alumina, fatty acid compounds such as soap, various coupling agents, etc. The method for this treatment is also not particularly limited, and can be carried out according to known methods.

[0036] (c) Luminescence characteristics The material of the present invention has a phosphorescence intensity of 1×10 when excited by a He-Cd laser light source with a wavelength of 325 nm. 3 Cd / m 2 or more, and the afterglow brightness after 30 minutes has elapsed since the light source was turned off after 5 minutes of irradiation with the light source is 1×10 -2 Cd / m 2 The light source and the like can be publicly known or commercially available devices, and a general measurement environment (such as a dark place) can be used.

[0037] As described above, the material of the present invention has the characteristics of not only having high phosphorescence intensity when excited by the light source but also having relatively high afterglow brightness after the light source is turned off, and can therefore maintain a desired brightness for a relatively long period of time.

[0038] The phosphorescence brightness above is typically 1×10 3 Cd / m 2 That's all, but especially 2×10 3 Cd / m 2 The upper limit of the phosphorescence brightness is preferably 5×10 3 Cd / m 2 It can be, but is not limited to, the degree.

[0039] The afterglow brightness is usually 1×10 -2 Cd / m 2That's all, but especially 2×10 -2 Cd / m 2 It is preferable that the value is 8×10 or more. -2 Cd / m 2 It is more preferable that the upper limit of the afterglow brightness is, for example, 10×10 -2 Cd / m 2 It can be, but is not limited to, the degree.

[0040] As described above, the material of the present invention preferably has the following light-emitting characteristics depending on its composition. For example, a crystalline material having composition A exhibits a phosphorescence intensity peak in the wavelength range of approximately 460 to 600 nm, which corresponds to yellow-green, when irradiated with a 325 nm He-Cd laser light source. Furthermore, a crystalline material having composition B exhibits (a) a phosphorescence intensity peak in the wavelength range of approximately 420 to 550 nm, which corresponds to blue-green, and (b) a phosphorescence intensity peak in the wavelength range of approximately 380 to 450 nm, which corresponds to purple to blue-violet, when irradiated with a 325 nm He-Cd laser light source.

[0041] 2. Manufacturing method of phosphorescent material The present invention provides a method for producing a luminous material made of corner-free, approximately spherical particles of an Sr-Al-RO based composite oxide (where R represents at least one rare earth element), comprising the steps of: (1) a step of preparing a mixed solution containing a Sr raw material, an Al raw material, and an R raw material (mixed solution preparation step); (2) a step of granulating the mixture to prepare a granular precursor having a median diameter (D50) of 120 μm or more (granulation step); (3) A step of heat-treating the granular precursor at 1200 to 1500°C in a non-oxidizing atmosphere (heat-treatment step). The present invention also encompasses a method for producing a phosphorescent material, which comprises the steps of:

[0042] Mixed liquid preparation process In the mixed solution preparation step, a mixed solution containing a Sr raw material, an Al raw material, and an R raw material is prepared.

[0043] The Sr raw material, Al raw material, and R raw material can be compounds containing each element, such as oxides, hydroxides, carbonates, nitrates, sulfates, phosphates, and chlorides. Therefore, examples of Sr raw materials include strontium carbonate and strontium nitrate. Examples of Al raw materials include aluminum oxide (alumina) and aluminum hydroxide. Examples of R raw materials include dysprosium nitrate, europium nitrate, dysprosium oxide, and europium oxide. These raw materials are generally provided in a powder form, but are not limited thereto. These raw materials can be publicly known or commercially available, or can be prepared by a known manufacturing method.

[0044] These raw materials can be blended to achieve a predetermined (Sr+R):Al molar ratio. This molar ratio can be adjusted to the ratio described above in "1. Luminescent Materials." For example, if composition A is the target, the materials can be blended within a range of approximately (Sr+R):Al = 0.9:2 to 1.1:2. If composition B is the target, the materials can be blended within a range of approximately (Sr+R):Al = 3.8:14 to 4.2:14. These materials can then be mixed with a solvent to prepare a mixed solution. The Sr:R ratio can also be adjusted to the ratio described above in "1. Luminescent Materials."

[0045] The solvent is not particularly limited, and examples that can be used include a) water, b) water-soluble organic solvents such as alcohols (ethanol, isopropyl alcohol, etc.), and c) mixed solvents of water and water-soluble organic solvents.

[0046] In the present invention, various additives can also be appropriately blended into the mixed solution as needed, such as binders (polyvinyl alcohol, carboxymethyl cellulose, higher alcohols, fatty acid derivatives, higher alcohol derivatives, metal soaps, silicones, etc.), dispersants (water-soluble acrylic dispersants, ammonium polycarboxylate, etc.), humectants (ethylene glycol, propylene glycol, etc.), antifoaming agents (acetylene glycol antifoaming agents, etc.), and binding agents (water glass, sodium aluminate, boric acid-based inorganic materials, metal salts, etc.).

[0047] A mixed solution can be prepared by uniformly mixing these components. Mixing can be carried out using a device such as a ball mill. The solid content of the mixed solution can be appropriately changed depending on, for example, the raw material composition, particle size, etc., and is not particularly limited, but from the standpoint of granulation production efficiency, etc., it is usually preferably about 30 to 40 wt %.

[0048] Granulation process In the granulation step, the mixed liquid is granulated to produce a granular precursor having a median diameter (D50) of 120 μm or more (preferably 150 μm or more).

[0049] The granulation method is not particularly limited, and for example, spray granulation (spray drying), fluidized bed granulation, etc. can be used. This allows for the production of a granular precursor having a predetermined median diameter. In this case, granulation can be carried out for a predetermined time so as to obtain a granular precursor having a median diameter of 120 μm or more (preferably 150 μm or more). If the median diameter of the obtained granular precursor is less than 120 μm (particularly less than 150 μm), it can be appropriately adjusted, for example, by classification, so that the median diameter becomes 120 μm or more (preferably 150 μm or more).

[0050] Furthermore, when the obtained particulate precursor contains an organic component, a degreasing step can be carried out prior to the heat treatment step described below.

[0051] The degreasing step can be suitably carried out, for example, in an oxidizing atmosphere at a temperature in the range of 600 to 1000° C. This makes it possible to more reliably remove organic components.

[0052] Furthermore, in the present invention, prior to the heat treatment step, components that can become an inorganic glass flux, including silica, alumina, boron, etc., can be added in advance. The amount of addition is not particularly limited, but is preferably about 1 to 5 mass %, more preferably 2 to 4 mass %.

[0053] Heat Treatment Process In the heat treatment step, the granular precursor is heat treated in a non-oxidizing atmosphere at 1200 to 1500° C. By carrying out the heat treatment, the predetermined luminous material of the present invention can be obtained.

[0054] As mentioned above, the heat treatment temperature is usually about 1200 to 1500°C, and preferably 1250 to 1450°C. The heat treatment atmosphere may be any non-oxidizing atmosphere, and suitable examples include a reducing atmosphere (e.g., hydrogen gas) and an inert gas atmosphere (e.g., nitrogen gas, helium gas). The heat treatment time can be adjusted appropriately depending on the heat treatment temperature, and can be, for example, within a range of about 1 to 10 hours, but is not limited to this.

[0055] The luminous material thus obtained is in the form of a powder, and each particle has a roughly spherical shape without corners, although it is permissible for a small amount of particles with corners to be contained within a range that does not impair the effects of the present invention.

[0056] Furthermore, the obtained phosphorescent material typically has a median diameter (D50) of 120 μm or more, and particles with a particle size of 100 μm or less account for 40% or less by number. However, if necessary, a crushing process or the like can be carried out. This breaks down the temporarily formed aggregates, allowing the desired particles to be obtained. Furthermore, after the crushing process, the material can be classified as necessary. This allows the removal of coarse particles. The crushing method is not particularly limited, as long as it is carried out under mild conditions to the extent that it breaks down the temporarily formed aggregates and minimizes the generation of pulverized material with corners. For example, it may be carried out using a known or commercially available device such as a roll crusher.

[0057] 3. Use of luminous materials The material of the present invention can be used in the same manner as known or commercially available luminous materials (luminous pigments). For example, it can be used in the form of a powder composition containing a powder of the material of the present invention, or in the form of a liquid paint containing the material of the present invention. In this case, the content of the material of the present invention can be appropriately adjusted depending on the desired luminous properties, etc.

[0058] Furthermore, the applications are not limited to fields that require the ability to emit light in the dark, and the material can be widely used in, for example, instrument dials, clock faces, road signs (including card rails and road markings), signs, and other components that can emit light in the dark (daily necessities, miscellaneous goods, etc.). [Example]

[0059] The features of the present invention will be described in more detail below with reference to examples, but the scope of the present invention is not limited to these examples.

[0060] Example 1 27.4 kg of strontium carbonate, 34.8 kg of alumina, 82 g of dysprosium nitrate pentahydrate, and 415.7 g of europium nitrate hexahydrate were weighed and placed in a ball mill along with 120 kg of alumina balls. 2 kg of polyvinyl alcohol (product name "GOHSENOL GH17R" manufactured by Mitsubishi Chemical Corporation), 530 g of a water-soluble acrylic acid dispersant (product name "Jurymer AC-10SL" manufactured by Toagosei Co., Ltd.), 15 g of a release / dispersant (product name "SN Dispersant 5468" manufactured by San Nopco), 380 g of a humectant (propylene glycol), 310 g of aluminum sulfate n-hydrate, and 135 L of pure water were added to the ball mill and stirred for 10 hours. A precursor slurry was thus obtained (molar ratio of Sr:Al:Eu:Dy = 4:14:0.02:0.01). The resulting precursor slurry was spray-dried (rotary atomizer type) to prepare precursor powder under the following spray-drying conditions: gas inlet temperature 220°C, precursor slurry flow rate 13 L / min, atomizer rotation speed 7500 rpm. Next, 3.9% by mass of boric acid was added to and mixed with the precursor powder, and the resulting mixed powder was then degreased. The degreasing treatment was carried out in air at 900°C for 6 hours. After that, the furnace was purged with nitrogen for 2 hours, and then heat treatment was carried out at 1300°C for 3 hours in a mixed gas atmosphere of 4% hydrogen gas and 96% nitrogen gas. The treated product thus obtained was crushed in a roll crusher to obtain the desired particulate sample.

[0061] Example 2 27.2 kg of strontium carbonate, 34.8 kg of alumina, 82 g of dysprosium nitrate pentahydrate, and 415.7 g of europium nitrate hexahydrate were weighed and placed in a wet attritor together with 120 kg of alumina balls. 2.3 kg of polyvinyl alcohol (product name "GOHSENOL GM14R" manufactured by Mitsubishi Chemical Corporation), 700 g of a water-soluble acrylic acid dispersant (product name "JURYMER AC-10SL" manufactured by Toagosei Co., Ltd.), 16 g of a release / dispersant (product name "SN Dispersant 5468" manufactured by San Nopco), 400 g of a humectant (ethylene glycol), 85 g of an antifoaming agent (product name "OLFIN AF-103" manufactured by Nissin Chemical Industry Co., Ltd.), and 138 L of pure water were then added to the wet attritor and stirred for 4 hours. In this way, a precursor slurry was obtained (molar ratio of Sr:Al:Eu:Dy=3.97:14:0.02:0.01). The obtained precursor slurry was spray-dried (rotary atomizer type) in the same manner as in Example 1 to prepare a precursor powder. Next, 3.0 mass% of boric acid was added to and mixed with the precursor powder, and the resulting mixed powder was then debound. The debounding treatment was carried out in air at 850°C for 4 hours. After that, the furnace was purged with nitrogen for 2 hours, and then heat treatment was carried out in a mixed gas atmosphere of 4% hydrogen gas and 96% nitrogen gas at 1245°C for 4 hours. The treated product thus obtained was crushed in a roll crusher to obtain the desired particulate sample.

[0062] Example 3 34.3 kg of strontium carbonate, 43.5 kg of alumina, 130 g of dysprosium oxide, and 306 g of europium oxide were weighed and placed in a ball mill along with 120 kg of alumina balls. 2.9 kg of polyvinyl alcohol (product name "Gohsenol GH14R" manufactured by Mitsubishi Chemical Corporation), 875 g of a water-soluble acrylic acid dispersant (product name "Aron A-30SL" manufactured by Toagosei Co., Ltd.), 20 g of a release / dispersant (product name "SN Dispersant 5023" manufactured by San Nopco), 504 g of a humectant (ethylene glycol), 75 g of an antifoaming agent (product name "Surfynol DF-75" manufactured by Nissin Chemical Industry Co., Ltd.), and 134 L of pure water were then added to the ball mill and stirred for 10 hours. In this way, a precursor slurry was obtained (molar ratio of Sr:Al:Eu:Dy=4:14:0.03:0.012). The obtained precursor slurry was spray-dried (rotary atomizer type) in the same manner as in Example 1 to prepare a precursor powder. Next, the precursor was sieved through a 300 μm sieve, and 3.4 mass% of boric acid was added and mixed with the resulting powder. The resulting mixed powder was then debound. The debounding treatment was carried out in air at 800°C for 6 hours. The furnace was then purged with nitrogen for 2 hours, after which heat treatment was carried out at 1350°C for 6 hours in a mixed gas atmosphere of 4% hydrogen gas and 96% nitrogen gas. The resulting treated material was crushed in a roll crusher to obtain the desired particulate sample.

[0063] Example 4 27.4 kg of strontium carbonate, 34.8 kg of alumina, 104 g of dysprosium oxide, and 245 g of europium oxide were weighed and placed in a ball mill along with 120 kg of alumina balls. 2.3 kg of polyvinyl alcohol (product name "Gohsenol GH17R" manufactured by Mitsubishi Chemical Corporation), 700 g of a water-soluble acrylic acid dispersant (product name "Aron A-30SL" manufactured by Toagosei Co., Ltd.), 16 g of a release / dispersant (product name "SN Dispersant 5068" manufactured by San Nopco), 404 g of a humectant (ethylene glycol), 44 g of an antifoaming agent (product name "Surfynol DF-75" manufactured by Nissin Chemical Industry Co., Ltd.), and 134 L of pure water were then added to the ball mill and stirred for 10 hours. In this way, a precursor slurry was obtained (molar ratio of Sr:Al:Eu:Dy=3.958:14:0.03:0.012). The resulting precursor slurry was spray-dried (spray nozzle type, without a rotary atomizer) to prepare a precursor powder. The spray-drying conditions were a gas inlet temperature of 550°C and a precursor slurry delivery rate of 22 L / min. Next, 3.5% by mass of boric acid was added to and mixed with the precursor powder, and the resulting mixed powder was then degreased. The degreasing treatment was carried out in air at 800°C for 6 hours. After that, the furnace was purged with nitrogen for 2 hours, and then heat treated at 1345°C for 8 hours in a mixed gas atmosphere of 3% hydrogen gas and 97% nitrogen gas. The treated product thus obtained was crushed in a roll crusher and sieved through a sieve with 250 μm openings to remove coarse particles, and the target particulate sample was obtained.

[0064] Example 5 35.8 kg of strontium carbonate, 26.0 kg of alumina, 530 g of dysprosium oxide, and 130 g of europium oxide were weighed and placed in a ball mill along with 120 kg of alumina balls. 2.0 kg of polyvinyl alcohol (product name: Gohsenol GH17R, manufactured by Mitsubishi Chemical Corporation), 470 g of a water-soluble acrylic acid dispersant (product name: Aron A-30SL, manufactured by Toagosei Co., Ltd.), 18 g of a release / dispersant (product name: SN Dispersant 5068, manufactured by San Nopco), 428 g of a humectant (ethylene glycol), 62 g of an antifoaming agent (product name: Surfynol DF-75, manufactured by Nissin Chemical Industry Co., Ltd.), and 120 L of pure water were then added to the ball mill and stirred for 10 hours. In this way, a precursor slurry was obtained (molar ratio of Sr:Al:Eu:Dy=0.96:2:0.025:0.015). The obtained precursor slurry was spray-dried (rotary atomizer type) in the same manner as in Example 1 to prepare a precursor powder. Next, 2.8% by mass of boric acid was added to and mixed with the precursor powder, and the resulting mixed powder was then debound. The debounding treatment was carried out in air at 800°C for 6 hours. After that, the furnace was purged with nitrogen for 2 hours, and then heat-treated at 1420°C for 4 hours in a mixed gas atmosphere of 2% hydrogen gas and 98% nitrogen gas. The resulting processed material was precisely crushed in a roll mill and then in a dry ball mill using alumina balls, and a particulate sample remaining between sieves with 250 μm and 90 μm openings was obtained.

[0065] Example 6 45.0 kg of strontium carbonate, 32.7 kg of alumina, 683 g of dysprosium oxide, and 1610 g of europium oxide were weighed and placed in a ball mill along with 120 kg of alumina balls. 3.0 kg of polyvinyl alcohol (product name "GOHSENOL GH14R" manufactured by Mitsubishi Chemical Corporation), 875 g of a water-soluble acrylic acid dispersant (product name "Aron A-30SL" manufactured by Toagosei Co., Ltd.), 20 g of a release / dispersant (product name "SN Dispersant 5068" manufactured by San Nopco), 505 g of a humectant (ethylene glycol), 75 g of an antifoaming agent (product name "Surfynol DF-75" manufactured by Nissin Chemical Industry Co., Ltd.), and 135 L of pure water were then added to the ball mill and stirred for 10 hours. In this way, a precursor slurry was obtained (molar ratio of Sr:Al:Eu:Dy=0.958:2:0.03:0.012). The obtained precursor slurry was spray-dried (rotary atomizer type) in the same manner as in Example 1 to prepare a precursor powder. Next, 2.8% by mass of boric acid was added to and mixed with the precursor powder, and the resulting mixed powder was then debound. The debounding treatment was carried out in air at 800°C for 6 hours. After that, the furnace was purged with nitrogen for 2 hours, and then heat treatment was carried out at 1415°C for 4 hours in a mixed gas atmosphere of 2% hydrogen gas and 98% nitrogen gas. The treated material thus obtained was crushed using a roll crusher and sieved through a sieve with 250 μm openings to remove coarse particles, yielding the desired particulate sample.

[0066] Example 7 A precursor powder was prepared and heat-treated in the same manner as in Example 6. The resulting treated product was crushed using a roll crusher to obtain a particulate sample remaining between sieves with openings of 250 μm and 45 μm.

[0067] Example 8 32.7 kg of strontium carbonate, 45.0 kg of alumina, 455 g of dysprosium oxide, and 1,074 g of europium oxide were weighed and placed in a planetary ball mill along with 120 kg of alumina balls. 2.6 kg of polyvinyl alcohol (product name: Gohsenol GH22, manufactured by Mitsubishi Chemical Corporation), 950 g of a water-soluble acrylic acid dispersant (product name: Aron T-50, manufactured by Toagosei Co., Ltd.), 28 g of a release / dispersant (product name: SN Dispersant 5468, manufactured by San Nopco), 480 g of a humectant (ethylene glycol), 30 g of a humectant (propanol), 87 g of an antifoaming agent (product name: Surfynol DF-58, manufactured by Nissin Chemical Industry Co., Ltd.), and 140 L of pure water were then added to the ball mill and stirred for 10 hours. In this way, a precursor slurry was obtained (molar ratio of Sr:Al:Eu:Dy=0.972:2:0.02:0.008). The obtained precursor slurry was spray-dried (spray nozzle type, without rotary atomizer) in the same manner as in Example 4 to prepare a precursor powder. Next, 2.5% by mass of boric acid was added to and mixed with the precursor powder, and the resulting mixed powder was then degreased. The degreasing treatment was carried out in air at 900°C for 6 hours. After that, the furnace was purged with nitrogen for 2 hours, and then heat treatment was carried out at 1400°C for 5 hours in a mixed gas atmosphere of 42% hydrogen gas and 98% nitrogen gas. The treated material thus obtained was crushed using a roll crusher and sieved through a sieve with 250 μm openings to remove coarse particles, yielding the desired particulate sample.

[0068] Comparative Example 1 A precursor slurry was obtained in the same manner as in Example 2 (molar ratio of Sr:Al:Eu:Dy=3.97:14:0.02:0.01). After adding and mixing 3.0 mass% of boric acid to the obtained precursor slurry, the mixture was packed into an alumina bowl and 5 × 10 -2After evacuation to 100 Pa, the sample was purged with nitrogen. This process was repeated three times, and the sample was heated to 1380°C over 13 hours in a mixed gas atmosphere of 4% hydrogen gas and 96% nitrogen gas, and then aged for four hours. After that, the sample was cooled to 300°C in a furnace, and the flow gas was switched to nitrogen. The sample was removed from the furnace at 50°C. The heat-treated sample was crushed in a roll crusher, then precisely pulverized in a high-speed hammer mill, and sieved through a sieve with 250 μm openings to remove coarse particles, yielding the desired particulate sample.

[0069] Comparative Example 2 A precursor slurry was obtained in the same manner as in Example 6 (molar ratio of Sr:Al:Eu:Dy=0.958:2:0.03:0.012). The obtained precursor slurry was spray-dried (spray nozzle type, without rotary atomizer) in the same manner as in Example 4 to prepare a precursor powder. Next, 3.0 mass% of boric acid was added to and mixed with the precursor powder, and the resulting mixed powder was then degreased. The degreasing treatment was carried out in air at 800°C for 5 hours. After that, the furnace was purged with nitrogen for 2 hours, and then heat treated at 1450°C for 5 hours in a mixed gas atmosphere of 2% hydrogen gas and 98% nitrogen gas. The resulting treated material was precisely crushed using a roll crusher and then a dry ball mill using alumina balls, and then sieved through a sieve with 90 μm openings to remove coarse particles, yielding the desired particulate sample.

[0070] Test Example 1 The physical properties of the samples obtained in each of the examples and comparative examples were measured. The results are shown in Table 1. The results of observation of particle shape are shown in Figure 1. Each physical property was measured as follows.

[0071] (1) Particle shape The particle shapes of all particles within the field of view of the sample were observed using a scanning electron microscope "JEM-6380LA" manufactured by JEOL Ltd.

[0072] (2) Median diameter and particle size distribution The particle size distribution was measured on a number basis using a laser diffraction particle size distribution analyzer "MT-3000" (manufactured by Microtrac-Bell Co., Ltd.), and the median diameter D50 was calculated. In the particle size distribution, the percentage of particles with a particle size of 100 μm or less was calculated.

[0073] (3) Evaluation of phosphorescent properties The phosphorescence properties of the obtained samples were evaluated as follows. Absolute PL (fluorescence) quantum yield measurements (fluorescence lifetime and phosphorescence measurements, fluorescence spectrum measurements) were performed using a Quantaurus-Tau compact fluorescence lifetime measurement system "C11367" (Hamamatsu Photonics K.K.). The phosphorescence intensity was measured by excitation with a 5mW output He-Cd laser 325nm light source. The residual brightness was measured by irradiating the sample powder with the above light source for 5 minutes, then turning the light source off and 30 minutes later. Additionally, in each of the obtained fluorescence spectra, the wavelength (nm) of the peak showing the maximum intensity and the presence or absence of a peak at a wavelength of 400 nm±10 nm were also measured.

[0074] (4) Bulk density of powder The bulk density of the obtained powder sample was measured as follows: Apparent bulk density (ρ b ) was as per the Japanese Industrial Standard JIS-Z2504:2012. Also, the tapped bulk density (ρ t ) conforms to the Japanese Industrial Standard JIS-R1628:1997.

[0075] [Table 1]

[0076] As is clear from the results in Table 1, the luminous materials of the examples, which have specific particle shapes, median diameters, etc., have high initial luminance and afterglow luminance.

[0077] Test Example 2 As representative examples, the particle shapes of Examples 2 and 7 and Comparative Example 2 were observed with a scanning electron microscope, and the results are shown in FIG.

[0078] As is clear from the results in Figure 1, the particles constituting the particulate samples of Examples 2 and 7 are roughly spherical with no corners. It can also be seen that the particle surfaces have finer irregularities and voids. In contrast, the particles constituting the particulate sample of Comparative Example 2 are irregularly shaped with corners, like rock.

Claims

1. A method for producing a luminous material made of particles of an Sr—Al—R—O based composite oxide (where R represents at least one rare earth element), comprising: (1) preparing a mixed solution containing a Sr raw material, an Al raw material, and an R raw material; (2) granulating the mixture to prepare a granular precursor having a median diameter (D50) of 120 μm or more; (3) A step of heat treating the granular precursor at 1200 to 1500°C in a non-oxidizing atmosphere. A method for producing a phosphorescent material, comprising:

2. The method according to claim 1, further comprising a step of crushing the heat-treated product obtained in the step (3).

3. 2. The method according to claim 1, wherein the ratio of (Sr+R):Al in the mixed solution is (Sr+R):Al=0.9:2 to 1.1:2 or (Sr+R):Al=3.8:14 to 4.2:

14.

4. The method of claim 1 , wherein the mixture contains a solvent.

5. The method of claim 1 , wherein the granulation is carried out by spray granulation.

6. The method of claim 1, wherein the mixed solution contains Eu and Dy as R, and the molar ratio of Eu:Dy is Eu:Dy=1:0.2-1.

7. The Sr-Al-R-O based composite oxide is Sr １－ｎ R ｎ Al ２ O ４ (where 0<n<1) and / or Sr ４－ｎ R ｎ Al １４ O ２５ (wherein 0<n<4) The method of claim 1 .

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