JP2019052271A - Manufacturing method of fluorescent material - Google Patents

Abstract

To provide a manufacturing method of a fluorescent material capable of providing similar effect to burning in reduction atmosphere even under ambient air environment, and capable of manufacturing a fluorescent material emitting fluorescence from blue to green by ultraviolet irradiation.SOLUTION: A manufacturing method includes a process for accommodating a shell in a sealed container so that space volume based on weight of the shell of 100 g is 500 ml or less, and a process for burning the sealed container accommodating the shell in ambient air environment at a temperature of 700°C to 1000°C. Thereby, a fluorescent material having similar fluorescence property by burning in reduction atmosphere even by burning in the ambient air environment can be manufactured and similar effect to reduction burning can be obtained with a simple method. Since a raw material is shell to be wasted, waste can be effectively utilized.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a method for producing a fluorescent material produced by firing a shell.

  There are various scallops, oysters, clams, etc., but accurate statistics on the amount of these shells are scarce. Of these, scallop and oyster shells are estimated to be about 350,000 tons and about 200,000 tons, respectively. The main component of the shell is calcium carbonate (calcite or aragonite) and has a porous skeleton structure. The effective use that has been put to practical use so far includes a wide variety of materials such as chalk, snow melting material, soil improvement material, white line paint mixture, VOC removal material, desulfurization / dephosphorization material, antibacterial / deodorant material, and fertilizer. In recent years, application to fluorescent materials has also been studied.

  Patent Document 1 discloses that a phosphor can be produced by firing a scallop shell at a temperature exceeding 100 ° C., and that the color of the phosphor changes by controlling the firing temperature. Patent Document 2 discloses that a powder containing calcium carbonate as a main component obtained by baking shells emits light in one or more emission bands by adding excitation energy, and a food additive that uses this as a label. Is disclosed.

Patent Document 3 discloses a technique in which an extract obtained by extracting a fired powder of shells with water is used as a fluorescent material for an aqueous fluorescent paint. Patent Document 4 discloses a technique in which shell powder is used as a Ca source material of a phosphor having CaAl ₂ O ₄ as a mother crystal.

JP 2004-359923 A JP 2011-227066 A JP 2011-162728 A JP 2007-131773 A

  Shells emit fluorescence only by firing, and the fluorescence wavelength range and emission intensity differ depending on the firing atmosphere. Of these, firing in a reducing atmosphere is necessary to obtain a fluorescent material that emits strong blue to green fluorescence.

  However, in order to perform firing in a reducing atmosphere, equipment for that is required, and it takes much time and cost compared to firing in an air atmosphere. None of Patent Documents 1 to 3 considers firing in a reducing atmosphere. Further, Patent Document 4 is not a technique for firing the shell itself, but there is a description of a reducing atmosphere, but only firing in a reducing atmosphere by a normal method is considered.

  The present invention has been made in view of such circumstances, and can obtain the same effect as firing in a reducing atmosphere even in an air atmosphere, and produce a fluorescent material that emits blue to green fluorescence by ultraviolet irradiation. An object of the present invention is to provide a method for producing a fluorescent material that can be used.

  (1) In order to achieve the above object, the method for producing a fluorescent material according to the present invention includes a step of housing the shell in a sealed container so that a space volume is 500 ml or less with respect to a weight of 100 g of the shell, and the shell And a step of firing the sealed container containing the material at an air atmosphere at a temperature of 700 ° C. or higher and 1000 ° C. or lower.

  As a result, a fluorescent material having the same fluorescence characteristics as firing in a reducing atmosphere can be produced even in firing in an air atmosphere, and the same effects as in reducing firing can be obtained by a simple method. In addition, since the raw material is a shell that is discarded, the waste can be effectively used.

  (2) Moreover, the manufacturing method of the fluorescent material of the present invention is characterized in that in the step of storing the shell, the space is stored so that the space volume is 200 ml or less with respect to 100 g of the weight of the shell. Thereby, a fluorescent material closer to that obtained by reduction firing can be produced.

  (3) Moreover, the manufacturing method of the fluorescent material of the present invention is characterized in that the space volume of the sealed container is calculated using the weight of the shell and the density of the shell for each shell type measured in advance. Thereby, it is not necessary to measure the volume of the shell to be accommodated, and the space volume of the sealed container can be easily set to a predetermined value.

  According to the present invention, it is possible to obtain the same effect as firing in a reducing atmosphere even in an air atmosphere, and to produce a fluorescent material that emits blue to green fluorescence by ultraviolet irradiation. In addition, since the raw material is a shell that is discarded, the waste can be effectively used.

It is a conceptual diagram of the manufacturing method of the fluorescent material of this invention. It is a graph showing the light emission wavelength of the fluorescent material which baked the scallop shell by changing the firing atmosphere. It is a graph showing the light emission wavelength of the fluorescent material which fired the oyster shell by changing the firing atmosphere. It is a graph showing the light emission wavelength of the fluorescent material which fired the clam shell by changing the firing atmosphere. It is a graph showing the light emission wavelength of the fluorescent material which baked the sea shell of Shijimi by changing baking atmosphere. It is a graph showing the light emission wavelength of the fluorescent material produced by housing scallop shells in a mortar and firing them in an air atmosphere.

  As a result of diligent research, the inventors of the present invention can obtain the same effect as firing in a reducing atmosphere even in an air atmosphere by storing the shell in a sealed container and firing it. The present inventors have found that a fluorescent material that emits light can be produced. Hereinafter, embodiments of the present invention will be described.

  Fluorescence or phosphorescence is a phenomenon in which an element in a ground state is excited by irradiation with an electromagnetic wave (ultraviolet ray, X-ray, electron beam) having a specific wavelength and emits light when returning to the original ground state. In addition, there is a phenomenon (luminescence) in which light emission continues even after the incident energy (excitation light) observed in the oxide light emitter is interrupted, and the fluorescent material according to the present invention includes not only fluorescent materials. Those having phosphorescent properties are also included.

[Method for producing fluorescent material]
A method for producing the fluorescent material of the present invention will be described. FIG. 1 is a conceptual diagram of a method for manufacturing a fluorescent material. First, a shell is accommodated in a sealed container so that a space volume is 500 ml or less with respect to a weight of 100 g of the shell. The space volume is a difference obtained by subtracting the volume of the shell to be accommodated from the volume of the sealed container. The volume of the shells to be accommodated may be measured each time, but may be calculated by using the weight of the shells to be accommodated and the density of the shells for each kind of shells measured in advance. Further, the density of the shell may be referred to a value described in a document or the like instead of a measured value. By dividing the weight of the shell by the density of the shell, the volume of the shell can be calculated. By doing so, it is not necessary to measure the volume of the shell to be accommodated each time, and the space volume of the sealed container can be easily set to a predetermined value. For example, the density of the shells of scallops, varies depending particle size distribution ^is 2.5g / cm ³ ~3.2g / cm 3 order.

  The space volume is preferably 200 ml or less, more preferably 100 ml or less, with respect to 100 g of the weight of the shell. This is because if the space volume is small, the inside of the sealed container becomes a reducing atmosphere earlier at the time of firing, and the fluorescent property of the obtained fluorescent material becomes closer to that of the reduced firing.

  When a sealed container contains shells and is fired in a sealed state, it is necessary that outside air does not enter the container and can withstand the firing temperature. Therefore, the sealed container is preferably a magnetic crucible with a lid.

  The shell may be crushed and stored. Moreover, when it can accommodate without grind | pulverizing, it may be accommodated as it is or may be roughly crushed and accommodated. Further, the type of the shell may be one type or two or more types.

  Moreover, in order to make the inside of a sealed container into a reducing atmosphere earlier at the time of baking, 1 wt% or less of organic matter may be mixed with shells and stored in the sealed container with respect to 100 g of shell weight. When an organic substance exceeding 1 wt% is mixed and baked with respect to the weight of 100 g of the shell, the organic substance remains in the state of char, tar, etc., and the phosphor becomes dirty in black and affects the fluorescence characteristics of the fluorescent material. May give. When mixing an organic substance with a shell, in order to make the properties of the fluorescent material uniform, it is preferable to pulverize both the shell and the organic substance and mix them with a ball mill or the like. The organic matter to be mixed is preferably derived from a plant body such as wood chips or vegetation. The organic substance to be mixed may contain a trace amount of Mn, Cl, F, Ni, Cu, Zn, Sr, and the like.

  Next, firing is performed under predetermined firing conditions. The firing atmosphere is an air atmosphere from the viewpoint of production cost, but the shell itself is accommodated in a sealed container, so any atmosphere is acceptable. The firing temperature is 700 ° C. or higher and 1000 ° C. or lower. When firing at a temperature lower than 700 ° C. or higher than 1000 ° C., the fluorescent properties of the fluorescent material change. The firing time is not particularly limited, but is preferably 10 minutes or longer and 2 hours or shorter, and more preferably 30 minutes or longer and 1 hour or shorter.

  The sealed container after firing is preferably opened after the whole is cooled. Moreover, you may grind | pulverize the fluorescent material after cooling to the average particle diameter D50 further match | combined with the intended purpose. The pulverization can be performed using a ball mill or the like. The average particle diameter D50 can be measured by a laser diffraction / scattering method.

  Through the above steps, the same effect as that obtained by firing in a reducing atmosphere can be obtained even in an air atmosphere, and a fluorescent material that emits blue to green fluorescence can be produced by ultraviolet irradiation. In addition, since the raw material is a shell that is discarded, the waste can be effectively used. For example, by filling a mold with cement paste or cement mortar and embedding a fluorescent material on the surface of the mold before it is hardened, a fluorescent concrete member in which the fluorescent material is embedded in a hardened cement body can be obtained. Further, it can be used by being kneaded into a resin material that can transmit light having an excitation wavelength.

[Experiment]
First, scallops, oysters, clams and swordfish shells were fired under different firing atmospheres. The firing conditions were an air atmosphere, a CO ₂ flow, and an H ₂ flow (3 vol%, balance N ₂ ), a firing temperature of 1000 ° C., and a firing time of 1 hour. After cooling, the produced fluorescent material was irradiated with short-wave ultraviolet light of 254 nm, and the emission wavelength was examined. 2 to 5 are graphs showing emission wavelengths of fluorescent materials obtained by firing scallops, oysters, clams and swordfish shells by changing the firing atmosphere.

As a general tendency, red fluorescence was observed in the air-fired product, and blue fluorescence was observed in the CO ₂ fired (non-oxidized fired) and H ₂ fired (reduced fired). The characteristics of each type of shell are as follows.

The scallop shell was fired in the atmosphere and a red fluorescence of 600 nm was observed. When the reduction with CO ₂ and H ₂ became stronger, the fluorescence gradually changed to 450 nm blue fluorescence. The oyster shell showed a behavior similar to that of the scallop shell, but the green-blue color of 480 nm became stronger when it was reduced and fired with H ₂ . The clam shells had weak red fluorescence even when fired in the air. Clam shells were found to have little effect on fluorescence properties due to the difference in atmosphere. The sea urchin shell was fired in air and CO ₂ , and red fluorescence of 600 nm was observed. The one fired with H ₂ showed a remarkable green-blue fluorescence of 500 nm. It is thought that the seashell of Shijimi has a higher Mn content than other shells and is slow to reduce.

Next, 200 g of scallop shells crushed to a bulk density of 1.33 g / ml were placed in a magnetic crucible with a lid of 290 ml and then fired at 1000 ° C. for 1 hour. . The space volume was 113 ml with respect to 100 g of shells. After cooling, the produced fluorescent material was irradiated with short-wave ultraviolet light of 254 nm, and the emission wavelength was examined. FIG. 6 is a graph showing the emission wavelength of the fluorescent material at that time. For comparison, the emission wavelengths of fluorescent materials of normal air atmosphere firing, CO ₂ atmosphere (non-oxidizing atmosphere) firing and H ₂ atmosphere (reducing atmosphere) firing that are not accommodated in the crucible are also described.

It was found that the emission wavelength of the fluorescent material fired in the crucible is located between the emission wavelength of CO ₂ atmosphere firing and the emission wavelength of H ₂ atmosphere firing. As a result, it was found that calcination in the crucible was more reduced than CO ₂ atmosphere calcination. This is presumably because the organic matter on the surface of the shell is thermally decomposed, and the inside of the crucible becomes a reducing atmosphere by the pyrolysis gas. For this reason, when the space volume is small, the amount of oxygen in the crucible also decreases, so that the organic matter on the surface of the shell becomes difficult to burn, and the crucible is considered to be in a reducing atmosphere more quickly.

Next, in order to measure the amount of organic matter on the surface of the shell, the weight loss of the ground scallop shell up to 600 ° C. was examined. As a result, it was confirmed that there was almost no weight reduction. Therefore, it is considered that the organic matter on the surface of the shell is about 1.5 wt% at the maximum and about 0.2 wt% at the minimum with respect to the weight of the shell. Considering the amount of O ₂ required to completely burn the organic matter, if the space volume is 500 ml or less with respect to the shell weight of 100 g, the organic matter on the shell surface will not be completely burned at the time of firing. It can be a reducing atmosphere.

  From the above, the method for producing a fluorescent material according to the present invention can produce a fluorescent material having the same fluorescence characteristics as that of firing in a reducing atmosphere even when firing in an air atmosphere, and obtains the same effect as reduction firing in a simple method. It was confirmed that it was possible.

Claims (3)

Storing the shell in a sealed container so that the space volume is 500 ml or less with respect to a weight of 100 g of the shell;
And baking the sealed container containing the shell at a temperature of 700 ° C. to 1000 ° C. in an air atmosphere.   The method for producing a fluorescent material according to claim 1, wherein the step of housing the shell includes housing the shell so that a space volume is 200 ml or less with respect to a weight of 100 g of the shell.   The method for producing a fluorescent material according to claim 1, wherein the space volume of the sealed container is calculated using a weight of the shell and a density of the shell for each kind of shell measured in advance.

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