JP2008297427A - Method for producing phosphor and production device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method capable of easily and rapidly producing a phosphor, and a production device suitable to execute the method. <P>SOLUTION: The method comprises steps of making a phosphor raw material containing a compound constituting a phosphor base body and an activator element exist in an insulating cavity between conductive fiber layers; irradiating the conductive fiber layers with electromagnetic wave to generate electric discharge within the cavity; and producing the phosphor from the phosphor raw material by the effect thereof. As the conductive fiber layer, a carbon fiber layer is preferred, and a felty carbon fiber layer is particularly preferred. As the electromagnetic wave, microwave is preferred. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a phosphor manufacturing method and a manufacturing apparatus that can be widely used in electrical equipment such as a display device such as a display panel and a lighting device such as a fluorescent lamp.

Various methods are disclosed as a method for producing a phosphor, and examples thereof include a solid phase method and an ion implantation method.
The solid phase method is a method in which a predetermined amount of a compound containing an element constituting the phosphor matrix and a compound containing an activator element are mixed and fired at a predetermined temperature for a predetermined time to obtain a phosphor by an intersolid reaction. (Phosphor handbook). For example, Patent Document 1 describes a method of manufacturing a phosphor by mixing a copper compound and a halogen compound in zinc sulfide and firing the mixture. Patent Document 2 describes a method for producing a phosphor powder by mixing and baking calcium oxide powder, europium fluoride powder, magnesium oxide powder and silicon dioxide powder.
The ion implantation method is a method for obtaining a phosphor by ionizing and accelerating an activator element into a compound containing an element constituting the phosphor matrix. For example, Patent Document 3 and Patent Document 4 describe a phosphor manufacturing method and an ion implantation apparatus using an ion implantation method.
JP-A-7-62341 JP 2006-265307 A Japanese Patent Publication No.53-17624 Japanese Patent Laid-Open No. 6-179869

However, the solid-phase methods as described in Patent Document 1 and Patent Document 2 have a baking process of several hours in a gas phase in a non-oxidizing atmosphere, so that the process is complicated and time-consuming, and the manufacturing cost is also high. .
Further, the ion implantation method described in Patent Document 3 has a problem that when the ion current is increased to shorten the processing time, the surface of the phosphor crystal is decomposed and melted. In order to solve this problem, as described in Patent Document 4, intermittent ion implantation and cooling also require an implantation time of about 4 hours. Furthermore, a phosphor manufacturing apparatus using an ion implantation method is expensive because it includes a vacuum apparatus that houses a base crystal substrate, an ion source part of an activator, and an ion extraction part that extracts ionized activator.

  Therefore, an object of the present invention is to provide a method capable of quickly producing a phosphor by a simpler method than before and a production apparatus suitable for carrying out the method.

  As a result of various studies to solve the above-mentioned problems, the present inventors cause discharge and heat accompanying it to act on a phosphor material containing a compound constituting the phosphor matrix and an activator element serving as a light emission center. As a result, the phosphor was successfully manufactured in a short time, and the problems were solved.

  That is, in the present invention, a phosphor raw material containing a compound constituting a phosphor matrix and an activator element is present in an insulating gap sandwiched between conductive fiber layers, and the conductive fiber layer is irradiated with electromagnetic waves. Then, the phosphor is produced from the phosphor raw material by generating discharge in the gap, and the phosphor production method.

The conductive fiber layer is a layer made of closely entangled conductive fibers, and a large number of conductive fiber tips protrude from the surface of the layer. Therefore, when the conductive fiber layer is irradiated with an electromagnetic wave, the conductive fiber layer absorbs the electromagnetic wave, and electrolysis concentrates on the tip of the fiber protruding on the surface of the layer, so that the insulating property sandwiched between the conductive fiber layers is Discharge occurs in the gap. Further, since the discharge energy is changed to thermal energy, the gap is at a high temperature.
Therefore, when the phosphor material containing the compound constituting the phosphor matrix and the activator element serving as the emission center is disposed in the gap sandwiched between the conductive fiber layers, and the conductive fiber layer is irradiated with electromagnetic waves, The phosphor matrix is subjected to an electronic attack due to electric discharge and has a rough surface structure, and the activator element melts at a high temperature on the surface of the matrix, thereby generating a phosphor.

  The present invention also relates to an apparatus for performing the above-described method, which is a phosphor manufacturing apparatus provided with a reaction vessel, and an insulating gap sandwiched between conductive fiber layers is formed in the reaction vessel. A phosphor material introduction means for supplying a phosphor material into the gap, and an electromagnetic wave irradiation means for irradiating the conductive fiber layer with an electromagnetic wave so as to cause a discharge in the insulating gap. The present invention relates to a phosphor manufacturing apparatus.

  According to the method and apparatus of the present invention, a phosphor is manufactured by a simple operation such as irradiating an electromagnetic wave on a conductive fiber layer in a state where the phosphor raw material is present in a gap sandwiched between the conductive fiber layers. be able to. In addition, the phosphor can be manufactured in a very short time.

  FIG. 1 shows the basic steps of the phosphor manufacturing method according to the present invention. Note that the flowchart of FIG. 1 is exemplary, and the manufacturing method of the present invention is not limited to the process of FIG.

In the phosphor manufacturing method according to the present invention, it is important that discharge occurs. A phosphor cannot be produced simply by irradiating an electromagnetic wave in the atmosphere to raise the temperature. For example, when the phosphor material is put in an electronic crucible and irradiated with microwaves, the phosphor material becomes high temperature, but the generation of the phosphor in a short time was not confirmed.
This indicates that both discharge and heat act on the generation of the phosphor. This discharge and thermal energy are determined by the electromagnetic wave output, the electromagnetic wave absorption performance of the conductive fiber, the width of the void (or the volume of the void), and the volume of the conductive fiber layer. That is, when the electromagnetic wave output is constant and the gap volume is increased, the discharge frequency is decreased. Therefore, if the heat insulation is constant, the temperature in the gap is also lowered accordingly. Therefore, it is preferable to adjust the electromagnetic wave output in accordance with the reaction temperature and the void volume required for producing the desired phosphor.

The conductive fiber layer according to the present invention requires a capacitance capable of storing a voltage that breaks the insulation of the gap in order to generate a discharge, and also needs a thickness to have a heat insulation property that maintains a high temperature. is there. Therefore, the conductive fiber layer according to the present invention preferably has a thickness of 0.5 mm or more, and preferably has a volume of a cube having a side of 0.5 mm or more. Although the preferred thickness / volume of the conductive fiber layer varies depending on the relationship between the electromagnetic wave output and the gap width, for example, two conductive fiber layers are disposed with an electromagnetic wave output of 500 to 1000 W and a gap width of 0.5 to 5 mm. In this case, each conductive fiber layer preferably has a thickness of about 5 to 10 mm / volume of about 400 to about 13,000 mm ^3, and more preferably a thickness of about 5 to 10 mm / volume of 500 to 7000 mm ³ . The shape of the conductive fiber layer is not particularly limited, but in the case of a shape having a corner such as a rectangular parallelepiped shape, it is preferable to round the corner because sparks are likely to occur at the corner.

As the conductive fiber layer, a carbon fiber layer is preferable. In particular, a felt-like carbon fiber layer is preferable. Since the carbon fiber layer has high conductivity, it easily absorbs electromagnetic waves. In addition, since heat insulation is high, it is difficult for heat generated by discharge to escape from the inside of the gap to the outside, and the inside of the gap can be kept at a high temperature (1000 ° C. or higher), while the outside of the carbon fiber layer is difficult to reach a high temperature. Easy and safe. Moreover, since it has high thermal stability, it is suitable for continuous use. In particular, carbon fibers fired at high temperature are preferable because of high thermal stability. Moreover, since the space | gap pinched | interposed between the carbon fiber layers becomes a reducing atmosphere, even a phosphor deactivated by oxidation, such as a sulfide-based phosphor, can be stably produced.
In particular, a felt-like carbon fiber layer (carbon felt) has a three-dimensional structure, a large surface area, and a large number of sharp fiber tips on the surface of the layer. Therefore, it is suitable for electromagnetic wave absorption and discharge generation.
In addition, steel wool, copper fiber, and tungsten wire can be used as the conductive fiber. These fibers can also be used in combination.

In the present invention, the space sandwiched between the conductive fiber layers is not only the space sandwiched between the two conductive fiber layers, but also the space surrounded by three or four sides by three or four conductive fiber layers. Or a void cut by cutting through one conductive fiber layer so that each conductive fiber layer is not energized. The insulating property of the air gap may be such that discharge is generated. The preferred width of the gap varies depending on the relationship between the electromagnetic wave output, the type of conductive fiber, and the thickness / volume of the conductive fiber layer. For example, the electromagnetic wave output is 500 to 1000 W, the thickness is 5 to 10 mm, and the volume is 500 to 7000 mm ^3. When two carbon felts are used, the preferred gap width is 0.4 to 5 mm, more preferably 0.5 to 3 mm, and particularly preferably 0.7 to 1.5 mm.

One of the features of the present invention is that the insulating voids where the phosphor formation reaction proceeds can be surrounded by the reducing conductive fiber layer, so that the reaction can proceed in a reducing atmosphere. It is done. Therefore, the production method of the present invention is a phosphor using Sn ²⁺ , Eu ²⁺ , Ce ³⁺ , Tb ³⁺ or the like as an activator, or a phosphor based on a sulfide such as CaS or ZnS. It is particularly suitable for producing a phosphor that needs to be produced in a reducing atmosphere.
In the case of a ZnS-based phosphor, for example, when the base ZnS is baked normally in the atmosphere, it is oxidized to ZnO, and the phosphor is easily deactivated. However, in the method of the present invention, ZnS is maintained. Therefore, the phosphor can be manufactured with high yield. Further, in the conventional solid phase method (firing method), N ₂ containing H ₂ or hydrogen sulfide is used as a reducing gas, which is not only troublesome but also dangerous. Since it is not necessary to use a reducing gas in order to obtain a neutral atmosphere, the phosphor can be manufactured safely and easily.

The phosphor material of the present invention contains a compound constituting the phosphor matrix and an activator element. As the matrix constituting compound and the activator element, a matrix constituting compound and an activator element used as a phosphor raw material in a solid phase method (firing method) conventionally performed can be used. For example, examples of the matrix constituting compound include zinc sulfide, barium sulfide, calcium sulfide and the like. Examples of the activator element include copper, silver, and europium. In addition, the activator elements include elements that are so-called coactivators (for example, Cl in ZnS: Ag, Cl, Al in ZnS: Cu, Al, and the like). The activator element may be added as it is depending on the type of element, reaction conditions, or the like, or may be added in the form of a compound containing the activator element. Moreover, you may add the adjuvant for accelerating, stabilizing, and assisting reaction like a normal solid-phase method. For example, a flux (such as a halide) may be added, and a reducing gas such as hydrogen sulfide or a reducing film such as an aluminum film may be added as a substance for assisting the reaction. The mixing ratio between the matrix constituent compound and the activator, the necessity of an auxiliary agent such as a flux, and the like may be the same as those in the conventional solid phase method.
The shape of the phosphor material may be a powder or a film shape, and may be appropriately adjusted according to the phosphor material and production conditions. Generally, a powder form or a particulate form is preferable. Further, although depending on the phosphor material, generally, the smaller the particle diameter, the higher the fluorescence intensity. The preferred particle size is 8.6 mesh or less, particularly preferably 74 mesh to 600 mesh. Moreover, it is preferable to heat as needed and to remove water and air adsorbed on the phosphor material.

The electromagnetic wave used in the present invention is not particularly limited in frequency and the like, but is preferably a microwave of 300 MHz to 300 GHz. In view of factors such as price and mass productivity, a 2.45 GHz microwave used in a microwave oven is particularly preferable. Therefore, a multimode electromagnetic wave irradiation apparatus can also be used in the method of the present invention. Since the reaction temperature can be changed according to the temperature required for the reaction, an electromagnetic wave irradiation device capable of adjusting the output is more preferable.
Under appropriate conditions, it is possible to produce a phosphor in a very short time, such as within one minute for a zinc sulfide-based phosphor and several minutes for a barium sulfide-based phosphor. The irradiation direction of the electromagnetic wave is not particularly limited, and it is sufficient that the conductive fiber layer is reliably irradiated.

The material of the reaction vessel used in the production apparatus of the present invention is preferably heat-resistant tempered glass or quartz.
In addition, if the conductive fiber layer is arranged in the reaction vessel so that one passage-like gap is formed, it is suitable for reliably supplying a raw material having low fluidity such as a solid into the gap. In addition, it is easy to prevent the product from being leaked. In particular, since raw materials such as rare earths and phosphors with secured performance are expensive, it is desirable to proceed the reaction reliably and reliably recover the product, but the above apparatus is used for handling such expensive solids. Very suitable.

In particular, the insulating gap is formed in the vertical direction, the raw material introduction part is installed at the upper part of the gap, the product recovery part is installed at the lower part, and the raw material introduction part and the product recovery part are communicated with the gap. If the conductive fiber layer is disposed close to the raw material introduced into the gap from the raw material introduction part so as to be held in a state of being narrowed in the gap of the conductive fiber layer, the phosphor raw material is removed from the introduction part. It is preferable that the raw material can be retained in the discharge region simply by charging. The preferred width of the gap varies depending on the state of the phosphor raw material, but is, for example, 0.5 to 1.5 mm when the raw material is powdery. Many fiber tips protrude from the surface of the conductive fiber layer, which is effective for holding the phosphor. Further, since the discharge occurs even if the conductive fiber layers are partially short-circuited, the lower end portion of the gap may be closed by contacting the lower conductive fibers to prevent the phosphor raw material from dropping.
The raw material introduction section and the product recovery section may be configured to communicate directly with the insulating gap or may be configured to communicate with each other through other members. For example, a glass tube may be arranged and communicated between the raw material introduction part and the gap.

  In the apparatus, the reaction product can be recovered by flowing an organic solvent (for example, petroleum ether) in which the phosphor does not deteriorate after completion of the reaction into the gap and washing out the reaction product in the product recovery unit. The washed out reaction product can be recovered without alteration by separating it from an organic solvent and naturally drying it. Or you may send out a fluorescent substance to a product collection | recovery part by ventilating gas in a space | gap. With such a configuration, since the generated phosphor can be taken out without moving the conductive fiber layer, the operation is simple.

  In the case where the production apparatus of the present invention is a continuous apparatus, it is preferable to provide means for moving the phosphor within the gap sandwiched between the conductive fiber layers. It is preferable that the phosphor raw material can be controlled to be held in the voids sandwiched between the conductive fiber layers during the reaction time. Ceramics or the like can be used as the transport medium. For example, a belt conveyor type ceramic sliding floor that moves in the horizontal direction is formed, conductive fiber layers are arranged on both sides thereof, and the phosphor material is sandwiched between the conductive fiber layers for a predetermined time. A continuous apparatus capable of mass production can be configured by controlling the length and moving speed of the conductive fiber layer so as to exist and allowing the reaction to proceed while moving the raw material.

Production of red phosphor As shown in FIG. 3, the phosphor production apparatus comprises an electromagnetic wave comprising a 2.45 GHz microwave transmitter and a resonator (manufactured by Cronics Giken Co., Ltd.) connected via a tuner by a coaxial tube. An irradiating device is provided, and a 2500 ° C. calcined carbon felt (length 40 mm × width 15 mm × thickness 0.5 mm) is disposed in close proximity in a glass tube (reaction vessel) through which the resonator is passed, so that an insulating gap is provided. (The distance between the carbon felts was about 1 mm). A raw material storage unit for supplying the phosphor raw material into the gap between the carbon felts is provided in the upper part of the reaction vessel, and the raw material storage unit is communicated with the gap by a glass thin tube to ensure the phosphor raw material. The raw material introduction part supplied into the gap is configured. The lower end of the reaction vessel communicates with the product collector.

A phosphor raw material was prepared by mixing zinc sulfide as a phosphor matrix constituent compound, manganese as an activator element, and magnesium chloride as an auxiliary agent in a molar ratio of 1: 0.15: 0.1 and pulverizing in an agate mortar. .
This phosphor material was introduced into the insulating gap sandwiched between the carbon felt pieces from the introduction portion, and irradiated with 2.45 GHz microwave 100 W for 30 seconds. The phosphor material was held between the carbon felt pieces and was present between the carbon felt pieces throughout the reaction time. After the irradiation, an organic solvent was poured from the raw material introduction part, and the reaction product was washed out and collected in a product collector. After separating the organic solvent and the reaction product, the reaction product was irradiated with black light, and an emission spectrum was measured. An emission spectrum as shown in FIG. 2A was observed, confirming the formation of a red phosphor (ZnS: Mn) (FIG. 2A).

Production of Green Phosphor A phosphor production apparatus similar to that used in Example 1 was used.
A phosphor raw material was prepared by mixing zinc sulfide as a phosphor matrix constituent compound, copper as an activator element, and magnesium chloride as an auxiliary agent in a molar ratio of 1: 0.01: 0.1 and pulverizing in an agate mortar. .
This phosphor material was introduced from the introduction part into an insulating gap sandwiched between carbon felt pieces, and irradiated with 2.45 GHz microwave 100 W for 40 seconds. The phosphor material was held between the carbon felt pieces and was present between the carbon felt pieces throughout the reaction time. After the irradiation, an organic solvent was poured from the raw material introduction part, the reaction product was washed out into a product collector, the organic solvent and the reaction product were separated, the reaction product was irradiated with black light, and an emission spectrum was measured. An emission spectrum having a peak at about 500 nm was observed, confirming the formation of a green phosphor (ZnS: Cu) (FIG. 2B).

Production of Blue Phosphor A phosphor production apparatus similar to that used in Example 1 was used.
Barium sulfide was mixed as a phosphor matrix constituent compound, europium oxide as a compound containing an activator element, and sulfur as an auxiliary agent were mixed at 1: 0.1: 0.2, and pulverized in an agate mortar. Further, a phosphor material was prepared by adding a crushed aluminum film piece as an auxiliary agent.
This phosphor raw material was disposed between the carbon felt pieces from the introduction part, and irradiated with 2.45 GHz microwave 100 W for 120 seconds. After irradiation, the reaction product was recovered by blowing air. The reaction product was irradiated with black light, and an emission spectrum was measured. An emission spectrum having a peak at about 475 nm was observed, confirming the formation of a blue phosphor (BaS: Eu) (FIG. 2C).

  According to Examples 1 to 3, according to the production method of the present invention, it is only 30 seconds to 120 seconds by a very simple operation of irradiating an electromagnetic wave with a phosphor raw material present in a gap sandwiched between conductive fiber layers. It was found that the phosphor can be manufactured in a very short time such as seconds.

  Moreover, it turned out that the phosphor of all three colors of RGB (red, green, blue) can be manufactured by Examples 1-3 by Examples 1-3. Moreover, the fluorescent composition which emits white fluorescence was able to be obtained by mixing each fluorescent substance of RGB manufactured in Examples 1-3.

  The XRD spectrum was measured for the matrix-forming compound (ZnS) used as the phosphor material in Example 2 and the produced phosphor. The spectrum of ZnS used as a raw material is shown in FIG. 4A, and the spectrum of the produced phosphor is shown in FIG. 4B. As shown in FIG. 4, ZnS has transitioned from the zincblende type to the wurtzite type, but the phosphor matrix (ZnS) is maintained, and no by-product (ZnO) due to oxidation is generated. . Therefore, it can be seen that the phosphor produced by the production method of the present invention has high purity.

Examination of production conditions Preferred production conditions were examined by changing the volume of the conductive fiber layer and the width of the gap (gap distance). A felt-like carbon fiber layer (carbon felt: CF) was used as the conductive fiber layer, and a microwave oven was used as the electromagnetic wave irradiation device. In a microwave oven, two cylindrical carbon felts are stacked vertically with a certain distance (gap distance) by interposing a ceramic member at the periphery of the cylinder, and sandwiched between CFs. A void was formed and irradiated with microwaves at 2.45 GHz · 700 W. The cylinder diameter of CF and the gap distance between CFs were appropriately changed, and the temperature in the gap at the time when electromagnetic wave irradiation was performed for 60 seconds was measured by infrared thermography from the observation window provided in the microwave oven.

As a result of the experiment, the smaller the gap distance between the CFs, the higher the temperature in the gap. On the other hand, when the gap distance between CFs was fixed and the CF cylinder diameter was gradually increased, the temperature within the gap tended to increase as the cylinder diameter first increased. However, the diameter increased at a certain point. As the temperature in the gap decreased, the temperature began to decrease. In addition, in order to keep heat in the gap and maintain a high temperature, the heat insulating property of CF is also important, and the thickness of CF is preferably 0.5 mm or more. If the gap distance between CFs is 1 to 5 mm, the thickness of CF is 5 to 10 mm, and the volume of CF is about 1500 to 7000 mm ³ , the measurement temperature in the gap reaches about 900 ° C. to about 1500 ° C., and various phosphors Could be manufactured in a short time.

  From the results of Example 5, in the manufacturing method of the present invention, the measurement temperature in the gap can reach a high temperature of 1000 ° C. or more in only 60 seconds only by setting the volume of CF and the gap distance between CFs to appropriate ranges. I understood. The actual temperature in the gap is considered to be higher than the temperature measured by thermography. Since the optimum temperature for manufacturing the phosphor varies depending on the type of the phosphor, it is necessary to change the temperature depending on the phosphor to be manufactured. From the results of this example, the temperature control is based on the gap distance and the conductive fiber layer. It was revealed that the volume can be adjusted appropriately by changing the volume. Further, it is considered that the high temperature is reached in a short time because the discharge energy is changed to thermal energy, and thus it is understood that a sufficient discharge is generated for the reaction.

As described above, in the production method of the present invention, it is possible to adjust the appropriate temperature and discharge frequency only by changing the volume of the conductive fiber layer and the width of the gap. However, it can be carried out using an apparatus that is impossible, and is extremely excellent in versatility.
As a matter of course, the temperature and the discharge frequency may be controlled by the electromagnetic wave output using an apparatus capable of adjusting the electromagnetic wave output.

It is a flowchart explaining the manufacturing method of this invention. (A) is the fluorescence spectrum of the red phosphor produced in Example 1, (B) is the fluorescence spectrum of the green phosphor produced in Example 2, and (C) is the fluorescence spectrum of the blue phosphor produced in Example 3. It is. A is a schematic view of the apparatus used in the examples and a longitudinal sectional view of the reaction vessel, and B is a transverse sectional view of the reaction vessel taken along line XX. (A) is an XRD spectrum of ZnS before microwave irradiation, and (B) is an XRD spectrum of ZnS after microwave irradiation.

Claims (5)

  A phosphor raw material containing a compound constituting the matrix of the phosphor and an activator element is present in an insulating gap sandwiched between the conductive fiber layers, and the conductive fiber layer is irradiated with electromagnetic waves in the gaps. A method for producing a phosphor, comprising: generating a discharge in the phosphor and producing a phosphor from the phosphor raw material by the action thereof.   The method for producing a phosphor according to claim 1, wherein the conductive fiber layer is a felt-like carbon fiber layer.   The manufacturing method of the fluorescent substance of Claim 1 or 2 whose said electromagnetic waves are a microwave.   A phosphor manufacturing apparatus including a reaction vessel, wherein an insulating gap sandwiched between conductive fiber layers is formed in the reaction vessel, and a fluorescent material for supplying a phosphor material in the gap A phosphor manufacturing apparatus comprising: a body material introducing means; and an electromagnetic wave irradiating means for irradiating the conductive fiber layer with an electromagnetic wave so as to cause a discharge in the insulating gap.   The insulating gap is formed in the vertical direction, the raw material introduction part is installed in the upper part of the gap, the product recovery part is installed in the lower part, and the raw material introduced into the gap from the raw material introduction part is the conductive fiber. The reaction product is transported to the product recovery section by flowing a transport medium composed of a gas or an organic solvent from the upper part of the gap after the reaction proceeds by being held in a state of being narrowed by a layer. The manufacturing apparatus according to claim 4, wherein: