JPH08109375A - Production of phosphor - Google Patents

Abstract

PURPOSE: To provide a method for producing a spherical phosphor capable of forming a dense and homogeneous fluorescent face. CONSTITUTION: In this method for producing a phosphor expressed by the composition formula Ln2 O3 :R or Ln2 O2 S:R (Ln is at least one kind of element selected from a group consisting of La, Gd, Lu and Y; R is at least one element selected from the lanthanoid group), MWO4 (M is at least one kind of metal among Ca and Mg) or CaWO4 :Pb, a raw material phosphor is treated in a high- temperature plasma controlling atmosphere and high frequency energy to prescribed values using argon, helium, krypton, neon, xenon, oxygen, nitrogen, hydrogen or a mixed gas of these two or more kinds of gases so that average temperature of plasma is >=1600 deg.C and <=6500 deg.C to provide sphere having 0.5-20μm average particle diameter and 1.0-1.5 ratio of long diameter to short diameter in each particle.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing a phosphor.

[0002]

2. Description of the Related Art Phosphors used in cathode ray tubes and fluorescent lamps are required to have a particle size of several μm from the viewpoint of luminous efficiency when excited by electron beams or ultraviolet rays. In order to obtain crystal grains having such a grain size, the phosphor is usually synthesized by a solid-phase reaction using a flux. However, the shape synthesized by using the flux is not a perfect spherical shape, but is a shape close to a polyhedron reflecting the shape and crystal structure of the raw material particles.

When such a phosphor is used to form a phosphor screen of a cathode ray tube, for example, there is a disadvantage that the light emission generated by electron beam excitation is not always sufficiently utilized as the light output from the phosphor screen. That is, when the shape of the phosphor particles is close to a polyhedron, a dense phosphor film cannot be obtained and voids are formed, and the smoothness of the aluminum back as a light reflecting film is poor and unevenness occurs. Therefore, diffuse reflection of the emitted light becomes large, which causes a loss of light. Similarly, when the above fluorescent material is used in a fluorescent lamp, a dense fluorescent film cannot be obtained, so that the light emission due to the ultraviolet excitation is not effectively utilized sufficiently.

For example, a color cathode ray tube is manufactured by the following method. A suspension (slurry) composed of a phosphor and a photosensitive resin is applied to the entire inner surface of the glass to form a fluorescent film, and ultraviolet rays are irradiated to polymerize only a desired region. After this, the fluorescent film in the region not irradiated with ultraviolet rays is washed away. At this time, if the light scattering of the fluorescent film is large, ultraviolet rays do not penetrate into the inside of the fluorescent film, so that the inside is less likely to polymerize. Therefore, it is difficult to form a sufficiently thick film that maximizes the brightness of the fluorescent film. Further, when the light scattering is large, it is difficult to obtain the designed fluorescent film pattern because the area other than the desired area is exposed and polymerized.

On the other hand, these phosphors may be sintered to be used as translucent phosphor flakes. In this case, a method is known in which after molding at room temperature, heating at 1200 to 1500 ° C. under high pressure is performed. At this time, if the packing density of the molded body is low, the molded body is likely to be deformed during sintering, and unevenness is likely to occur in the light emitting characteristics inside the sintered body.

Further, for example, MWO ₄ (where M is C
at least one of a and Mg) or CaW
Each of the O ₄ : Pb phosphors has an emission spectrum having a peak wavelength in the range of 400 to 500 nm, and has a problem that it is disadvantageous in terms of visibility because it emits light of a short wavelength. Further, the peak of the excitation spectrum of CaWO ₄ : Pb is considerably shifted to the long wavelength side of 254 nm.
There is a problem that the excitation efficiency is lowered when excited by 4 nm ultraviolet light.

The larger the total surface area of the particles contained in the fluorescent film, the larger the light scattering. Therefore, it is desirable that the particles have a spherical shape. Further, spherical particles having good dispersibility are also desirable in order to obtain the closest packing. Therefore, as an attempt to obtain phosphor particles having a shape as close to a spherical shape as described in B. C.
Grabmaier et al. Phys. Sta
t. Sol. (A) A method using an emulsion as shown in 130, K183 (1992) is known. However, the phosphor obtained by this method is an aggregate of fine particles, is opaque, and has poor crystallinity, so that re-firing is required. The shape of the phosphor particles obtained as a result is not necessarily perfectly spherical, and the particle size is also small, which is not preferable as a phosphor used in a cathode ray tube. When the phosphor obtained by this method is used as the raw material for the sintered body, since the particles themselves have voids, the packing density of the molded body is low,
Large deformation due to sintering.

As another attempt to obtain a spherical phosphor, Japanese Patent Laid-Open No. Sho 6-96
Japanese Unexamined Patent Publication No. 2-201989 discloses a method of heating a granulated phosphor raw material in high temperature plasma, and a rare earth oxysulfide is also contained in this phosphor.
However, the phosphor obtained by this method has a markedly low luminous efficiency because the whole is strongly colored, and the activator concentration desired as a practical phosphor cannot be obtained in terms of the emission color and the luminous efficiency. There was a flaw. In addition, in the case of a phosphor having a generally preferable particle size of 0.5 to 20 μm, most of the phosphor is evaporated to form ultrafine particles, and the ratio of the amount of spherical particles formed by melting is often small, and It was difficult to control this ratio.

Further, the problems of the individual phosphors applied to the above applications will be described. R. C. Rop
p: J. Electrochem. Soc. , 112
Gd ₂ as shown in Volume 181 (1965).
O ₃ : Eu belongs to the monoclinic crystal system. However, R.
S. Roth et al. : J. Res. Natio
nal Bureau of Standards, 6
4A, p. 309 (1960), G
The cubic crystal of d ₂ O ₃ is stable at room temperature, and in order to obtain a monoclinic crystal which is a stable phase at high temperature, after it is heated to 1200 ° C. or higher,
It needs to be rapidly cooled, which is difficult to manufacture by the usual phosphor firing method in a crucible. On the other hand, Araiet a
l. : J. Alloys and Compound
S., 192, p. 45 (1993), praseodymium-activated monoclinic Gd ₂ O ₃ has a short emission due to a green emission band that cannot be obtained with cubic Gd ₂ O _3. Although there is a possibility that it can be used for applications requiring light green emission, it is required to solve the manufacturing problems for obtaining a monoclinic crystal that is a stable phase at high temperature as described above.

[0010]

The present invention has been made to solve the above problems, and provides a method for producing a phosphor having a small particle size and a shape close to a true sphere.
The purpose is to obtain a cathode ray tube or a fluorescent lamp with high brightness by forming a dense and uniform fluorescent screen.

[0011]

[Means and Actions for Solving the Problems] The method for producing a phosphor of the present invention comprises: Ln ₂ O ₃ : R or Ln ₂ O ₂ S: R
(Where Ln is at least one element selected from the group consisting of La, Gd, Lu and Y, and R is at least one element selected from the lanthanide group), MWO
₄ (However, M is at least 1 of Ca and Mg
Seed) or CaWO ₄ : Pb compositional formula, in order to produce a plasma having an average temperature of 1600 ° C. or higher and 6500 ° C. or lower, argon, helium, krypton, neon, xenon, oxygen, nitrogen, Hydrogen or a mixed gas of two or more of these is used to treat in an atmosphere and high-temperature plasma in which high-frequency energy is controlled in a predetermined manner, and the average particle diameter is 0.5 to 20 μm. The ratio is made spherical in the range of 1.0 to 1.5.

Further, the method for producing a phosphor of the present invention is based on Ln
₂ O ₃ : R or Ln ₂ O ₂ S: R (where Ln is at least one element selected from the group consisting of La, Gd, Lu and Y, and R is at least one element selected from the lanthanide group) Element), MWO ₄ (where M is Ca
And at least one of Mg) or CaWO ₄ :
When manufacturing the phosphor represented by the composition formula of Pb, the high frequency power output is 5 to 100 kW, and the plasma gas flow rate is 20.
~ 150 l / min, carrier gas flow rate 5-50 l / min,
It is treated in high-temperature plasma generated under the condition that the inner diameter of the plasma generator surrounding cylinder is 30 to 100 mm, the average particle diameter is 0.5 to 20 μm, and the ratio of the major axis to the minor axis of each particle is 1.0. It is characterized in that it has a spherical shape in the range of up to 1.5.

Although R represents a lanthanide group element, among them, particularly useful elements as a phosphor are Ce, Pr,
Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm, Y
b. The phosphor produced by the method of the present invention preferably contains 0.001 to 5% by weight of ultrafine particles having a particle diameter of 0.2 μm or less.

The present invention will be described in more detail below.

In the method for producing a phosphor of the present invention, the raw material phosphor particles are introduced into a thermal plasma flame at an appropriate position together with a carrier gas, and a part of the raw material phosphor particles or a part of the surface of the raw material phosphor particles is introduced. It is evaporated and taken out of the thermal plasma in a short time and rapidly cooled to become ultrafine particles, and most of the other particles or the remaining particles after evaporation of the surface are dissolved to form liquid spheres due to surface tension, which are then rapidly cooled. Based on the principle of obtaining spherical particles. At this time, it is rapidly cooled without flowing the cooling gas, but it can be further cooled by flowing the cooling gas to the tail flame portion of the plasma. FIG.
Figure 2 shows the concept of the manufacturing equipment. Here, 10 is a plasma gas, 11 is a powder feeder with an improved electromagnetic feeder, 12 is a carrier gas supply cylinder, 13 is a powder supply port (nozzle structure is omitted), 14 is a high frequency oscillator, 15 is a coil, 16
Is a plasma flame, 17 is a reaction vessel, 18 is a cyclone, 19 is a cylinder surrounding the plasma generating part, and 20 is a cooling gas source.

In the conventional plasma field, many efforts have been made to increase the input, for example, Japanese Patent Laid-Open No. 63-85007.
As shown in the publication, it was often used as a heat source for producing ultrafine particles by pouring a raw material powder into a high temperature part of plasma and evaporating it. In this case, the temperature T _{4 of the} high temperature eddy current portion indicated by 21 in FIG. 2 reaches 10,000 ° C. However, conversely, the idea of lowering the temperature of the plasma has not been made because there is a problem that the flame tends to disappear when the raw material is charged, and even if the plasma is maintained, it becomes unstable.
The present invention is based on the fact that stable plasma can be generated at a lower temperature than before by selecting the high-frequency input, gas flow rate, and type optimally.

In the present invention, in order to control the ratio of ultrafine particles to spherical particles, the gas flow rate and type are appropriately selected, the high frequency input is mainly changed, and the temperature of the powder supply position is controlled according to the material characteristics of the phosphor. To do. Conventional high temperature plasma was not suitable for producing spherical phosphors. The reason for this is shown below. When one raw material particle is introduced into plasma at a certain temperature, the temperature distribution in the particle is lower than the plasma temperature, but the edge is high and the center is low. When the temperature of the central portion is equal to or higher than the melting point, the whole tends to melt and the edges tend to evaporate. In order to obtain a spherical phosphor, a temperature higher than the melting point of the phosphor is required. On the other hand, a high temperature deviating from the boiling point is unsuitable in order to consist mainly of spherical particles and to contain 0.001 to 5% by weight of ultrafine particles. In order to obtain the phosphor of the present invention having a particle size of about 0.5 to 20, the phosphor is not at a high temperature such as 10,000 ° C. but 160
It is desirable to supply the plasma having a melting point of 0 to 2500 ° C. or more and a temperature of about 6500 ° C.

The plasma flame has a temperature distribution as shown in FIG. Although it is possible to bring the feed position of the raw material powder to a low temperature portion such as 22 in FIG. 2, the present inventors find it difficult to control the ratio of the amounts of ultrafine particles and spherical particles by this method, It is possible to obtain favorable results by controlling the input from the power supply, the flow rate of gas and the type of gas to lower the average temperature of the swirl part and the powder supply port, and to make the temperature gradient at this position gentle. Found. That is, FIG.
As shown in the schematic diagram of Fig. 2, when the temperature is plotted from the central position of the two vortex flow centers in Fig. 2 in the plasma axial flow direction, the lowest temperature is obtained in the case where the temperature in the vortex region is high T _{42 and} the temperature is low T _41. The obtained position a of T ₁ does not change much. That is, by lowering the minimum temperature, the temperature gradient in the plasma could be made gentle. In this figure, T ₂ represents the plasma temperature at which the charged powder melts during a short residence time, and T ₃ represents the temperature at which the powder evaporates. The powder introduced from the powder supply port enters the plasma with a positional width of Δx. At this time, if the average temperature between T ₂ and T ₃ is the same, when the temperature gradient is gentle, it is possible to raise the temperature above the temperature at which all the particles can be melted and to evaporate an appropriate ratio of particles. On the other hand, when the temperature gradient is steep, particles exposed to temperatures above the evaporating temperature and below the melting temperature tend to coexist. At this time, even if the powder supply port is brought to a position such that the temperature is higher than the melting temperature, the ratio of the amount of particles that are higher than the temperature for evaporation is increased, and ultrafine particles exceeding the preferred range for the phosphor are generated. . As can be easily inferred from FIG. 3, when the temperature gradient is gentle, the ratio of the spherical particles to the ultrafine particles is controlled by the temperature even if the position distribution width of the powder fed from the powder supply port becomes small. A gentler gradient is easier, which leads to an improvement in powder throughput.

When this process is applied to a phosphor material, in the case of being represented by the composition formula of Ln ₂ O ₃ : R, the average plasma temperature of the portion into which the raw material powder is put is 2500 to 6
500 ° C is desirable. At 2500 ° C. or lower, the raw material is not completely melted and spheroidization is insufficient. At 6500 ° C or higher, the amount of evaporation is large and the amount of ultrafine particles is large. Similarly, for Ln ₂ O ₂ S: R, 2000 to 6000 ° C., Mg
160 for WO ₄ , CaWO ₄ and CaWO ₄ : Pb
0 to 5500 ° C is suitable for spheroidizing conditions.

The above-mentioned preferable temperature gradient is 1 when the diameter of the plasma generating portion surrounding cylinder 19 in FIG. 1 is 30 to 100 mm.
Input to high frequency power supply of ~ 28MHz is 10 ~ 200k
W, the output from the high frequency power source is 5 to 100 kW, and the plasma gas flow rate is 20 to 150 depending on the type of gas.
1 / min and the carrier gas flow rate was 5 to 50 l / min. When the lower limit of the diameter of the surrounding cylinder is 30 mm, the power input is 10 to 30 kW and the power output is about 5 to 15 k.
W, a plasma gas flow rate of 20 to 100 l / min, a carrier gas flow rate of 5 to 40 l / min, and a high frequency of 2 to 28 MHz are preferable. Also, the upper limit of the diameter of the outer cylinder is 100 mm.
In case of, power input 80 ~ 200kW, power output 40
~ 100 kW, plasma gas flow rate 100-150 l /
Min, carrier gas flow rate of 10 to 50 l / min, and high frequency of 1 to 5 MHz are preferable. Among the above conditions, the reason for limiting the diameter of the plasma generating portion surrounding cylinder is 30
If it is less than mm, an industrial throughput cannot be obtained and 100
A device larger than mm requires a large amount of power and is not realistic. Under these conditions, a stable plasma can be maintained without the flame disappearing, and spherical particles and an appropriate proportion of ultrafine particles can be obtained.

The plasma atmosphere is selected in order to obtain a preferable plasma temperature and to avoid deterioration of the raw material phosphor. For example, when Ln ₂ O ₃ : R and R = Eu, an atmosphere containing oxygen is desirable in order to easily generate plasma and avoid alteration of the matrix. On the other hand, when R = Pr or Tb, the oxygen content is avoided as much as possible. In the case of the Ln ₂ O ₂ S-based phosphor, it is necessary to avoid oxygen content as much as possible in order to avoid alteration of the matrix. Further, the coloration peculiar to the phosphor of this system due to the thermal plasma is reduced by mixing sulfur into the raw material.

The amount of the raw material powder to be introduced into the thermal plasma is about 50 g / min per unit when the raw material particle size is 0.5 to 20 μm by a combination of an appropriate powder supply device and the fluidity of the powder. It was possible and could be processed sufficiently at the above temperature.

As the raw material phosphor, Ln ₂ O ₃ : R or Ln ₂ O ₂ S: R (where Ln is La, Gd, L
at least one element selected from the group consisting of u and Y, R is at least one element selected from the lanthanide group), MWO ₄ (where M is at least one of Ca and Mg) or CaWO ₄ A compound represented by the composition formula of Pb is used.

In the present invention, JP-A-62-2019
Unlike the production method of Japanese Patent Publication No. 89, a phosphor having an activator concentration different from the activator concentration of the obtained phosphor and not granulated is used as a raw material. Such a raw material phosphor is manufactured using a flux. By acid-treating the particle surface of the raw phosphor or imparting a trace amount of an organic surfactant to improve the dispersibility and fluidity of the raw phosphor, the average particle diameter of the raw phosphor and the resulting spherical phosphor can be improved. The difference can be kept within 50%. The particle size of primary particles of the phosphor used as a raw material is preferably about 2 μm or more. This is because when the particle size of the primary particles is small, even if the diameter of the secondary particles obtained by aggregating the primary particles is 2 μm or more, the whole is melted and evaporated, and it is obtained by quenching it. This is because the resulting particles are often 0.2 μm or less. When the dispersibility of the phosphor used as the raw material is good, the particle size of the obtained phosphor is almost the same as the particle size of the raw phosphor. Therefore, the particle size of the obtained phosphor is
It can be controlled by the particle size and the degree of aggregation of the raw phosphor. Moreover, in order to obtain a phosphor having a shape close to a true sphere, conditions are set such that the entire raw material particles are not evaporated and the surface of the particles is completely melted. Such conditions can be achieved by adjusting the power of the plasma and the amount of the raw material phosphor supplied into the plasma. The phosphor particles according to the present invention can be obtained by melting the raw material particles under these conditions and rapidly solidifying the raw material particles while maintaining the spherical shape by the surface tension.

The average particle size of the phosphor particles produced by the method of the present invention is defined as 0.5 to 20 μm, when the average particle size is smaller than 0.5 μm or larger than 20 μm. This is because the brightness of the phosphor screen becomes low.

The reason why 0.001 to 5% by weight of ultrafine particles having a particle diameter of 0.2 μm or less is preferably contained is as follows. That is, when the content of the ultrafine particles exceeds 5% by weight, the light scattering increases, so that the light transmittance of the phosphor film made from this phosphor decreases and the practicality becomes poor. On the other hand, the inclusion of ultrafine particles within the above range improves the fluidity and dispersibility of the phosphor. For this reason, when the fluorescent film is formed by the sedimentation of the fluorescent material in the liquid or the application of the fluorescent material slurry, the fluorescent film becomes close to the closest packing. Therefore, diffused reflection in the fluorescent film is reduced, the transmittance of the film is improved, the ratio of light emission used as light output from the fluorescent screen is increased, and the brightness of the fluorescent screen is improved. On the other hand, during heat treatment of a color cathode ray tube or the like, the ultrafine particles act as a binder between spherical particles, and the adhesive force of the fluorescent film is strengthened. It should be noted that the phosphor just after the production is 0.2μ
If a large amount of ultrafine particles of m or less is included, ultrasonic cleaning is performed and the supernatant liquid is discarded to obtain 0.2 μm.
The following ultrafine particle contents are adjusted to fall within the above range.

The phosphor produced by the method of the present invention is
The ratio of the major axis and the minor axis of each phosphor particle (aspect ratio), that is, the ratio of the maximum diameter part and the minimum diameter part of each phosphor particle is in the range of 1.0 to 1.5,
It has a shape close to a sphere, with no protrusions such as edges. The ratio of the major axis and the minor axis of the phosphor particles is 1.0 to 1.2.
Is more preferable. When the fluorescent film having a particle shape that is almost spherical is formed and the fluorescent film is formed by sedimentation in a liquid or application of slurry, a fluorescent film close to the closest packing can be obtained. Also, since the total surface area of the particles is small in the fluorescent film formed using spherical phosphor particles,
Even with the same coating amount, light scattering is reduced and the light transmission amount is increased as compared with the case of using a conventional phosphor. Therefore, for example, when the fluorescent surface of a color cathode ray tube is formed by an optical printing method, since the light transmittance of the fluorescent surface is large, it is exposed to a deep portion of the fluorescent film. The film thickness can be increased, and the film thickness can be easily controlled. Moreover, since the film has a high light transmittance and is dense, a good quality fluorescent film pattern without unevenness or unevenness at the end portion due to light scattering can be obtained. Further, in both the color cathode ray tube and the single color cathode ray tube, since the phosphor film is close to the closest packing, the smoothness of the light reflecting metal film formed on the phosphor screen becomes good. Therefore, of the light emitted from the phosphor screen, the light of the portion that has proceeded to the electron beam excitation side can be efficiently reflected, and the brightness can be improved. In addition to this, since the light transmittance of the fluorescent film is high, the proportion of the light emitted from the fluorescent surface that travels in the direction opposite to the electron beam excitation side (the side observed by humans) increases, and Contribute to improvement.

In the present invention, it is preferable to appropriately change the production conditions according to the intended phosphor to adjust the suitable particle size and the content of fine particles. For example, Ln
When producing the phosphor represented by the composition formula of ₂ O ₃ : R, argon, helium, krypton, neon, xenon, oxygen, nitrogen, and nitrogen are added so that the average temperature of the plasma is 2500 ° C. or higher and 6500 ° C. or lower. Hydrogen or a mixed gas of two or more of these is used to treat in an atmosphere and high-temperature plasma in which high-frequency energy is controlled in a predetermined manner to form spherical particles having an average particle size of 0.5 to 15 μm and a particle size of 0.2 μm or less. It is preferable to adjust the content of the ultrafine particles of 0.001 to 1% by weight.

When the rare earth oxysulfide phosphor represented by the composition formula of Ln ₂ O ₂ S: R is produced, argon and helium are used so that the average temperature of the plasma is 2000 ° C. or higher and 5500 ° C. or lower. , Krypton, neon, xenon, oxygen, nitrogen, hydrogen, or a mixed gas of two or more of these, in a high-temperature plasma in which the atmosphere and high-frequency energy are controlled as desired, and the average particle size is 0.5.
It is preferable that the particles have a spherical shape of ˜15 μm and that the ultrafine particles having a particle size of 0.2 μm or less are contained in an amount of 0.001 to 0.5 wt%.

When producing a phosphor represented by the composition formula of MWO ₄ or CaWO ₄ : Pb, argon, helium, krypton and neon are used so that the average temperature of plasma is 1600 ° C. or higher and 5500 ° C. or lower. ,xenon,
Oxygen, nitrogen, hydrogen, or a mixed gas of two or more of these is used to perform treatment in high-temperature plasma in which the atmosphere and high-frequency energy are controlled as desired, and the average particle size is 0.5 to 2
It is preferable that the particles have a spherical shape of 0 μm and that ultrafine particles having a particle diameter of 0.2 μm or less are contained in an amount of 0.001 to 5% by weight.

The phosphor containing the ultrafine particles as described above has a high frequency power output of 5 to 100 kW and a plasma gas flow rate of 2.
0 to 150 l / min, carrier gas flow rate 5 to 50 l / min
The inner diameter of the plasma generator surrounding cylinder is 30 to 100 mm
It can be manufactured by treating in a high temperature plasma generated under the conditions of.

In the present invention, it is desirable to set the activator concentration of the raw phosphor to be different from the activator concentration after the thermal plasma treatment. Further, the luminous efficiency of the phosphor can be improved by performing re-baking at 600 to 1300 ° C. after the treatment in the high temperature plasma.

Further, suitable manufacturing conditions, average particle diameters, applications, etc. for each phosphor will be described in more detail.

For example, it is represented by the composition formula of Gd ₂ O ₃ : R (where R is at least one element selected from the lanthanide group), and at least a part of the crystal system is a monoclinic system, and the average is Phosphors which are spherical particles having a particle diameter of 0.5 to 15 μm and a ratio of major axis to minor axis of 1.0 to 1.5 and exhibiting red or green emission color are suitable for cathode ray tubes. Used. The average particle size of the Gd ₂ O ₃ : R phosphor used for the cathode ray tube is more preferably 1 to 10 μm. Such optimum range for the average particle size is empirically known. Monoclinic Gd ₂ used for cathode ray tubes
Since the emission color of the O ₃ : R phosphor differs depending on the type of R, its suitable application also differs. That is, monoclinic Gd
The emission color of ₂ O ₃ : Eu is deeper than that of cubic crystal, which is stable at low temperature, and is suitable for the red component of color cathode ray tubes, projection type cathode ray tubes or high color rendering fluorescent lamps. There is. In the case of monoclinic Gd ₂ O ₃ : Pr, its emission color changes from cubic red which is a low temperature stable type to yellow-green including a green emission band. Since the afterglow time of this light emission is as short as about 10 μs, it is suitable for a special cathode ray tube requiring a short afterglow. Monoclinic Gd ₂ O ₃ : Tb emits green light with high efficiency and is suitable for a green component of a projection type CRT.

In the rare earth oxysulfide phosphor represented by the composition formula of Ln ₂ O ₂ S: R, the spherical phosphor obtained by directly subjecting the phosphor raw material to thermal plasma treatment is strongly colored. For example, in the case of a Gd ₂ O ₂ S phosphor, a strong flesh color is exhibited and the visible light reflectance is about 30%. In addition, Y ₂ O ₂ S
In the case of a phosphor, a strong gray-purple body color is exhibited and the visible light reflectance is 10% or less. Therefore, the light emission is absorbed by the phosphor itself, and the light emission efficiency is significantly reduced. This body color is considered to be due to a phenomenon unique to oxysulfide, and is coloring not only on the surface of particles but also inside. This body color is obtained by subjecting the obtained spherical phosphor to 800 to 12 in a sulfur atmosphere.
It can be erased by heat treatment at 00 ° C.
Further, the degree of body color intensity can be reduced by adding sulfur to the raw material before the thermal plasma treatment.

In the case of a phosphor represented by Ln ₂ O ₃ : R,
The crystal system may change due to the thermal plasma treatment, and the emission color may change accordingly. For example, Ln = Y,
When R = Eu, the cubic crystal is usually stable, but when the thermal plasma treatment is performed, some monoclinic particles may be contained. The emission spectrum of this particle is centered around a wavelength of 623 nm, the emission color is deep red, and the emission efficiency is reduced. This is 10
When it is re-baked at 00 ° C, the whole is transformed into a low temperature stable phase cubic crystal, and the emission spectrum does not include a peak at 623 nm.
The color changes to red around 1 nm, and the luminous efficiency improves. When Ln = Gd, the phosphor subjected to the thermal plasma treatment is almost completely an aggregate of monoclinic particles. In this case, it can be used as it is depending on the purpose. On the other hand, depending on the purpose, it is possible to obtain a cubic phosphor while maintaining the spherical shape by further firing it at a temperature of 800 to 1200 ° C.

The activator concentration of the spherical rare earth oxysulfide phosphor obtained by the thermal plasma treatment is different from that of the starting phosphor. For example, Eu / Y in Y ₂ O ₂ S: Eu
Even if the atomic ratio is 4.0% in the raw material, it is 1.8% in the spherical phosphor subjected to the thermal plasma treatment, which is lower than 1/2. On the other hand, Eu / Y reaches about 40% in the ultrafine particles. As a result, the luminescent color of the spherical phosphor deviates from red and exhibits an orange color which is not preferable for a practical phosphor. If Ln = Y or Gd and the phosphor is Tb-activated, T
When the b concentration decreases, the blue component represented by the 415 nm emission line becomes stronger in the emission spectrum than the green component represented by the 544 nm emission line. In order to obtain a green-emitting phosphor, the atomic ratio of Tb / Ln needs to be 2 to 6%. However, when a raw material phosphor having an activator concentration in this range is used, Tb / Ln atoms are processed by thermal plasma treatment. Since the ratio is lowered, the desired emission color is deviated. Another example of the similar phenomenon will be described. For example, when Y ₂ O ₃ : Eu of the red phosphor for lamp is used as a raw material, the Eu / Y atomic ratio was 4.4% in the raw material, but the thermal plasma treatment In the case of the spherical phosphor, the amount is reduced to about 3.5%. On the other hand, the Eu / Y ratio reaches about 20% in the ultrafine particles. As a result, the emission color of the spherical phosphor is shifted from the desired red color to an orange color, and the emission efficiency is reduced by about 20%. Although the degree of change in the activator concentration depends on the thermal plasma processing conditions, for example, the amount of the raw material phosphor supplied, the change in the activator concentration cannot be eliminated at all. Therefore, in order to obtain the activator concentration in the spherical phosphor that can obtain a desired emission color, the activator concentration of the raw material phosphor is adjusted.

With respect to the spherical phosphor having the composition formula of MWO ₄ or CaWO ₄ : Pb, the emission spectrum is shifted to the long wavelength side, so that the luminous efficiency becomes bright. on the other hand,
Since the deviation of the excitation spectrum from 254 nm is small, when excited by ultraviolet rays of 254 nm, the excitation light efficiency is improved and the brightness of the fluorescent film is improved.

[0039]

Embodiments of the present invention will be described below.

Example 1 A Y ₂ O ₃ : Eu phosphor was used as a raw material. The average particle diameter of the raw material phosphor was measured by the Blaine method and found to be 4.5 μm. The phosphor according to the present invention was obtained by supplying this raw material phosphor into high-frequency thermal plasma, melting and quenching. The diameter of the plasma generator surrounding cylinder is 40 mm, and the plasma gas is argon 52
l / min, oxygen 27 l / min, carrier gas argon 10 l / min, cooling gas argon 30 l / mi
n, the power supply output was a plate voltage E _P = 10.0 kV, the I plate current P was 1.9 A, and the average temperature of the plasma was 3800 ° C. The raw material supply rate is 20 g / mi
It was n. The average particle diameter of the obtained phosphor was 4.8 μm as measured by the Blaine method. An electron micrograph of the obtained phosphor is shown in FIG. The ratio of the major axis to the minor axis of each phosphor particle obtained from this electron micrograph is 1.
It was in the range of 00 to 1.10. In addition, X of this phosphor
It was confirmed that the line diffraction pattern was the same as that of Y ₂ O ₃ , and the composition was Y ₂ O ₃ : Eu. When this phosphor was excited with an electron beam having an accelerating voltage of 10 kV and a current density of 1 μA / cm ² , the powder brightness was measured and found to be 98% of that of the raw phosphor.

Next, using the obtained phosphor, a phosphor screen having a coating weight of 7 mg / cm ² was formed by a sedimentation method, an aluminum back was applied, and then an electron gun was attached and exhausted.
A 7-inch projection type cathode ray tube was manufactured by sealing. When the luminance of this cathode ray tube was measured under the conditions of a voltage of 30 kV and a beam current of 200 μA, it was 790 ft-L. This value was 5% higher than the luminance of 750 ft-L of the cathode ray tube similarly manufactured by using the raw material phosphor.

Example 2 90% of oxalate coprecipitation product was obtained.
After being decomposed and baked at 0 ° C., it was baked at 1100 ° C. using an alkaline earth halide as a flux to obtain a La ₂ O ₃ : Pr phosphor having a Pr concentration of 0.1 mol%. The average particle diameter of the raw material phosphor was measured by the Blaine method and found to be 6.8 μm. The phosphor according to the present invention was obtained by supplying this raw material phosphor into high-frequency thermal plasma, melting and quenching. The diameter of the plasma generator surrounding cylinder is 40 mm, and the plasma gas is 60 l / m of argon.
in, carrier gas was argon 10 l / min, cooling gas was argon 30 l / min, and power supply output was E _P = 10.
0 kV, I _P = 1.8 A, and the average temperature of the plasma was 3600 ° C. The raw material supply rate is 15 g / mi
It was n. The average particle size of the obtained phosphor was 7.3 μm as measured by the Blaine method. The ratio of the major axis to the minor axis of each phosphor particle obtained from the electron micrograph was in the range of 1.00 to 1.15, and contained 0.3% by weight of ultrafine particles of 0.2 μm or less. When the powder brightness of this phosphor was measured under the same conditions as in Example 1, it was 78% of that of the starting phosphor. It is considered that the reason why the powder brightness is considerably lowered is that Pr is somewhat oxidized. Further, the emission color at this time was green, and a spectrum having peaks near 510 nm and around 670 nm was shown. This emission color was the same as that of the raw material phosphor, and the composition was also the same.

Next, using the obtained phosphor, a phosphor screen having a coating weight of 11 mg / cm ² was formed by a sedimentation method, and after applying an aluminum back, an electron gun was attached, and exhaust and sealing were performed. An inch projection type cathode ray tube was produced. About this cathode ray tube, voltage 30 kV, beam current 200 μA
When the luminance was measured under the conditions of, it was 300 ft-L. This value was 20% higher than the luminance of 250 ft-L of the cathode ray tube similarly manufactured by using the raw material phosphor. As described above, the phosphor of the present example has a higher brightness as a cathode ray tube, although the powder brightness is lower than that of the raw material phosphor. This is because the particle shape of the phosphor of this example is close to a true sphere.

Example 3 90% of oxalate coprecipitation product was obtained.
After decomposition and firing at 0 ° C, 1400 without using flux
The Eu concentration is 5 mol% Gd ₂ O by firing at ℃
₃ : Eu phosphor was obtained. The measured X-ray diffraction of the raw phosphor, mostly was the Gd ₂ O ₃ monoclinic, pattern of Gd ₂ O ₃ 5% cubic strongest peak ratio is also observed It was The average particle size of the raw material phosphor was 3.5 μm as measured by the Blaine method, but it was slightly agglomerated. The phosphor according to the present invention was obtained by supplying this raw material phosphor into high-frequency thermal plasma, melting and quenching. The diameter of the plasma generator surrounding cylinder is 40m
m, plasma gas is argon 52 l / min, oxygen 27
l / min, the carrier gas is argon 10 l / min,
Cooling gas is argon 30 l / min, power output is E _P =
The value was 10.0 kV, I _P = 1.7 A, and the average temperature of the plasma was 3500 ° C. The raw material supply rate is 20g
It was / min. The average particle diameter of the obtained phosphor was 4.2 μm as measured by the Blaine method. The ratio of the major axis to the minor axis of each phosphor particle obtained from the electron micrograph was in the range of 1.00 to 1.18. When the X-ray diffraction of the obtained phosphor was measured, it was found to be monoclinic Gd ₂ O ₃
It was confirmed that the pattern of cubic Gd ₂ O ₃ was not seen, and that it was almost completely a monoclinic Gd ₂ O ₃ : Eu phosphor. The obtained phosphor has a wavelength of 2
When the powder luminance was measured by exciting with a 54 nm ultraviolet ray, the value was 95% of that of the raw material phosphor.

Next, by applying the obtained phosphor to the inner surface of the glass tube using a nitrocellulose binder,
A 40 W rated fluorescent lamp was produced. Further, a similar fluorescent lamp was manufactured using the raw material phosphor. When the luminous fluxes of both fluorescent lamps were measured under rated input, the fluorescent lamp of Example 3 showed a value 3% higher than that of the raw fluorescent material.

Example 4 A Gd ₂ O ₃ : Eu phosphor belonging to the cubic crystal system was used as a raw material. The average particle diameter of the raw material phosphor was measured by the Blaine method to be 3.4.
μm. This raw material phosphor was supplied into high-frequency thermal plasma, melted and rapidly cooled to obtain a powder sample. This phosphor was suspended in water, ultrasonically washed and allowed to stand, the upper layer portion was removed, suction filtration was performed, and then drying was carried out at 100 ° C. to obtain the phosphor according to the present invention. The diameter of the plasma generator surrounding cylinder is 40 mm,
Plasma generating outer囲円barrel diameter 40 mm, the plasma gas is argon 52l / min, oxygen 27l / min, carrier gas argon 10l / min, the cooling gas is argon 30l / min, power supply output E _P = 10.0 kV, I
_P = 1.7 A, average temperature of plasma is 3500 ° C
Met. The raw material supply rate was 20 g / min. The average particle diameter of the obtained phosphor was 3.6 μm as measured by the Blaine method. An electron micrograph of the obtained phosphor is shown in FIG. The ratio of the major axis and the minor axis of each phosphor particle obtained from the electron micrograph is 1.00 to 1.1.
It was in the 0 range. This phosphor contained 0.2% by weight of ultrafine particles of 0.2 μm or less. The X-ray diffraction pattern of this phosphor was completely different from that of the starting phosphor, indicating that it was a monoclinic system. This phosphor was excited with an electron beam having an accelerating voltage of 10 kV and a current density of 1 μA / cm ² or ultraviolet rays having a wavelength of 254 nm to measure the emission spectrum. The main emission wavelength was 623 nm, and the emission chromaticity value was x = 0. 6
3, y = 0.35. These values are the main emission wavelength of the raw material phosphor of 611 nm and the emission chromaticity value x = 0.62,
It changed from y = 0.36.

Next, using the obtained phosphor, a phosphor screen having a coating amount of 7 mg / cm ² was formed by a sedimentation method, and after applying an aluminum back, an electron gun was attached, and exhaust and sealing were performed. An inch projection type cathode ray tube was produced. About this cathode ray tube,
When the luminance was measured under the conditions of a voltage of 29 kV and a beam current of 1500 μA, it was 3500 ft-L. This value is monoclinic Gd obtained by firing at 1300 ° C and quenching.
_The value was 30% higher than the luminance of 2700 ft-L of the cathode ray tube similarly manufactured using the ₂ O ₃ : Eu phosphor.

Example 5 As a raw material, a Y ₂ O ₃ : Eu phosphor belonging to a cubic crystal system was used. The Eu / Y atomic ratio was 4.4%. The average particle diameter of the raw material phosphor was measured by the Blaine method and found to be 3.2 μm. This raw material phosphor was supplied into a high-frequency thermal plasma, melted, rapidly cooled, and collected by a cyclone to obtain a phosphor composed of particles close to a true sphere. This phosphor was suspended in water, ultrasonically washed and allowed to stand, the upper layer portion was removed, suction filtration and drying were performed. The diameter of the plasma generator surrounding cylinder is 40 mm, the plasma gas is 52 l / min of argon, and 27 l / mi of oxygen.
n, carrier gas is argon 8 l / min, oxygen 2 l / min
min, the cooling gas was argon 30 l / min, the power supply output was E _P = 10.0 kV, I _P = 1.9 A, and the average temperature of the plasma was 3800 ° C. The raw material supply rate was 15 g / min. This phosphor contained particles of a slightly monoclinic crystal system in addition to the cubic crystal system. In addition, ultrafine particles having a particle size of 0.2 μm or less are 0.1
It was contained by weight%. This phosphor in air at 1100 ° C
The phosphor obtained by firing for 2 hours consisted only of particles of cubic crystal system. The average particle size of this phosphor was 3.8 μm as measured by the Blaine method. The ratio of the major axis to the minor axis of each phosphor particle obtained from the electron micrograph was in the range of 1.00 to 1.10. The ultrafine particles were fused and crystallized to some extent and adhered to the surface of the particles, but the amount was about 0.1%. The Eu / Y atomic ratio was 3.5%.

This phosphor was excited with an electron beam having an accelerating voltage of 10 kV and a current density of 1 μA / cm ² or an ultraviolet ray having a wavelength of 254 nm to measure the emission spectrum. The main emission wavelength was 611 nm, which was the same as the starting phosphor. there were. However, its luminous efficiency is 1 when excited by an electron beam as compared to the starting phosphor.
It was 10% and 80% when excited by ultraviolet rays.

Next, using the obtained phosphor, a phosphor screen having a coating amount of 7 mg / cm ² was formed by a sedimentation method, and after applying an aluminum back, an electron gun was attached, exhausted and sealed to 7 An inch projection type cathode ray tube was produced. About this cathode ray tube,
When the luminance was measured under the conditions of a voltage of 29 kV and a beam current of 1500 μA, it was 5300 ft-L. This value is 13 compared with the luminance of 4700 ft-L of the cathode ray tube which was similarly produced by using the raw material phosphor before the thermal plasma treatment.
It was a high value.

Example 6 As a raw material for the thermal plasma treatment, a Gd ₂ O ₃ : Pr phosphor belonging to the cubic crystal system was used. The average particle diameter of the raw material phosphor was measured by the Blaine method and found to be 3.2 μm. The phosphor according to the present invention was obtained by supplying this raw material phosphor into high-frequency thermal plasma, melting and quenching. The diameter of the plasma generator surrounding cylinder is 40 mm, and the plasma gas is argon 60 l / mi.
n, carrier gas argon 10 l / min, cooling gas argon 30 l / min, power supply output E _P = 10.0
kV, I _P = 1.7 A, average plasma temperature is 3
It was 500 ° C. The raw material supply rate is 20 g / min
Met. The average particle size of the obtained phosphor was 3.8 μm as measured by the Blaine method. The ratio of the major axis to the minor axis of each phosphor particle obtained from the electron micrograph is 1.
It was in the range of 00 to 1.10. In addition, X of this phosphor
The line diffraction pattern was completely different from that of the starting phosphor, indicating that it was a monoclinic system. This phosphor has an acceleration voltage of 10k
V, electron beam with a current density of 1 μA / cm ² or wavelength 254
When the emission spectrum was measured by exciting with an ultraviolet ray of nm, it showed a green emission color, and the emission chromaticity value was x = 0.31.
It was y = 0.51. In this emission characteristic, the raw material phosphor shows a red emission color, and the emission chromaticity value x = 0.64, y =
Compared with 0.28, it changed significantly.

Next, using the obtained phosphor, a phosphor screen having a coating amount of 7 mg / cm ² was formed by a sedimentation method, and after applying an aluminum back, an electron gun was attached, and exhausting and sealing were performed. An inch projection type cathode ray tube was produced. About this cathode ray tube,
When the luminance was measured under the conditions of a voltage of 29 kV and a beam current of 1500 μA, it was 580 ft-L. This value is
Monoclinic Gd ₂ O ₃ : P obtained by firing at 1300 ° C and quenching
Luminance of a cathode ray tube produced in the same manner using r phosphor 500
The value was 16% higher than that of ft-L.

Example 7 Gd ₂ O was obtained by decomposing and firing oxalate coprecipitation of gadolinium and europium at 1000 ° C.
₃ : Eu powder was obtained. When X-ray diffraction of this powder was measured, a cubic diffraction pattern was obtained. Next, this powder was supplied into high-frequency thermal plasma and melted and rapidly cooled to obtain a phosphor according to the present invention. The diameter of the plasma generator surrounding cylinder is 40 mm, and the plasma gas is 52 l of argon /
min, oxygen 27 l / min, carrier gas argon 10 l / min, cooling gas argon 30 l / min,
The power supply output was E _P = 10.0 kV, I _P = 1.6 A, and the average temperature of the plasma was 3300 ° C. The raw material supply rate was 15 g / min. The average particle size of this phosphor measured by the Blaine method was 1.5 μm. An electron micrograph of the obtained phosphor is shown in FIG. The ratio of the major axis to the minor axis of each phosphor particle obtained from the electron micrograph was in the range of 1.00 to 1.15. Further, when the ratio of cubic crystals to monoclinic crystals was calculated from the ratio of X-ray diffraction peaks of this phosphor, it was found that monoclinic crystals were contained in approximately 80%.

(Example 8) Y ₂ O ₂ S: Eu produced by the same flux method as the red phosphor for color TV was used as a raw material. However, the Eu / Y atomic ratio was set to 8.0%.
The average particle size of this raw material phosphor was 4.1 μm. This raw material phosphor was stirred in a 1/40 diluted nitric acid solution for 20 minutes, washed with water, suction filtered, replaced with alcohol and dried.
2% by weight of sulfur was added to this sample, which was introduced into high-frequency thermal plasma in an argon atmosphere, rapidly cooled, and collected by a cyclone. The diameter of the cylinder surrounding the plasma generation part is 40 mm, the plasma gas is 60 l / min of argon, the carrier gas is 10 l / min of argon, and the power output is E _P = 10.0 kV.
I _P = 1.5 A, average temperature of plasma is 3000
° C. The raw material supply rate was 20 g / min. Ultrasonic waves were applied to the obtained sample in water and the sample was allowed to stand still, and then the upper layer portion was removed to obtain spherical particles. The particle surface of this sample contained 0.5% of ultrafine particles of 0.2 μm or less. This sample had a gray-purple body color and had a visible light reflectance of 40%. In addition, this sample in a sulfur atmosphere,
The phosphor according to the present invention was obtained by firing at 900 ° C. for 1 hour.
FIG. 7 shows an electron micrograph of this phosphor. This phosphor was composed of spherical particles having an average particle size of 4.5 μm. The ratio of the major axis to the minor axis of each phosphor particle obtained from this electron micrograph was in the range of 1.00 to 1.10. The body color of this phosphor was white and the visible light reflectance was 94%. When X-ray diffraction of this phosphor was measured, it showed a diffraction pattern of oxysulfide. The Eu / Y atomic ratio of this phosphor was 3.7%. The emission color by electron beam excitation under the conditions of an accelerating voltage of 10 kV and a current density of 0.5 μA / cm ² was red, which is suitable for color TV.

(Comparative Example 1) Red phosphor Y ₂ for color TV
O ₂ S: Eu was used as a raw material. The Eu / Y atomic ratio was 4.1%. The average particle size of this raw phosphor is 4.3.
μm. This raw material phosphor was stirred in a 1/40 diluted nitric acid solution for 20 minutes, washed with water, suction filtered, replaced with alcohol and dried. This sample was introduced into high frequency thermal plasma and quenched. The plasma conditions are the same as in Example 8. Ultrasonic waves were applied to the obtained sample in water and the sample was allowed to stand still, and then the upper layer portion was removed to obtain spherical particles. This sample had a gray-purple body color and had a visible light reflectance of 8%. Further, this sample was subjected to 900 atmosphere in a sulfur atmosphere in the same manner as in Example 8.
Calcination was carried out at ℃ for 1 hour. The body color of this phosphor was white, but the Eu / Y atomic ratio was 1.8, and the emission color by electron beam excitation was orange, which is unsuitable for color TV.

Example 9 Gd ₂ O ₂ S: Pr having an average particle size of 5.2 μm produced by the flux method was used as a raw material. The Pr / Gd atomic ratio was 0.06%. A 1/100 diluted tamol aqueous solution was added to this raw material phosphor, suction filtration was performed, the alcohol substitution was performed, and drying was performed. This sample was introduced into high frequency thermal plasma and quenched. The diameter of the plasma generator surrounding cylinder is 40 mm, and the plasma gas is 60 l / m of argon.
in, nitrogen 5 l / min, carrier gas is argon 10
l / min, power supply output is E _P = 10.0 kV, I _P =
It was 1.4 A and the average temperature of the plasma was 2800 ° C. The raw material supply rate was 20 g / min. The resulting sample contained 1% ultrafine particles. After ultrasonic waves were applied to this sample in water and allowed to stand, the upper layer portion was removed to obtain spherical particles containing 0.1% of ultrafine particles. This sample had a flesh-colored body color, and the visible light reflectance was 32%. Further, this sample was subjected to 900 atmosphere in a sulfur atmosphere in the same manner as in Example 8.
The phosphor according to the present invention was obtained by firing at 1 ° C. for 1 hour. About 0.1% of the ultrafine particles were fused and left on a part of the surface of this phosphor. This phosphor was composed of white spherical particles having an average particle size of 6.1 μm and had a visible light reflectance of 93%. When X-ray diffraction of this phosphor was measured, it showed a diffraction pattern of oxysulfide. Pr / Gd atomic ratio is 0.0
5%. The emission color due to electron beam excitation showed a green color similar to that of the raw material.

Example 10 Y ₂ O ₂ S: Tb having an average particle size of 4.3 μm produced by the flux method was used as a raw material. The Tb / Y atomic ratio was 6.5%. A 1/100 diluted tamol aqueous solution was added to this raw material phosphor, suction filtration was performed, the alcohol substitution was performed, and the phosphor was dried. Sulfur of 3% by weight was added to this sample, which was introduced into high-frequency thermal plasma, rapidly cooled, and recovered by a cyclone. The diameter of the plasma generator surrounding cylinder is 40
mm, plasma gas 60 l / min of argon, hydrogen 2
l / min, the carrier gas is argon 10 l / min,
The power supply output was E _P = 10.0 kV, I _P = 1.4 A, and the average temperature of the plasma was 2800 ° C. The raw material supply rate was 15 g / min. Ultrasonic waves were applied to the obtained sample in water and the sample was allowed to stand still, and then the upper layer portion was removed to obtain spherical particles. This phosphor contains 0.05% ultrafine particles.
% Was included. This sample had a flesh-colored body color, and the visible light reflectance was 50%. Furthermore, this sample was used as Example 8.
Similarly to the above, the phosphor according to the present invention was obtained by firing at 900 ° C. for 1 hour in a sulfur atmosphere. This phosphor was composed of white spherical particles having an average particle diameter of 5.5 μm and containing 0.02% of distinguishable ultrafine particles, and had a visible light reflectance of 91%. Tb / Y
The atomic ratio was 3.5%. The emission spectrum by electron beam excitation was 10 times or more stronger in the 544 nmn band than in the 415 nm band, and showed a green color suitable as a phosphor for a projection-type cathode ray tube.

(Comparative Example 2) A CaWO ₄ phosphor (Comparative Example 2) was prepared by a conventional wet precipitation / calcination method. The average particle size of this phosphor measured by the Blaine method was 4.3 μm. When excited by ultraviolet rays or electron beams, the peak wavelength of the emission spectrum of this phosphor was 411 nm.
The chromaticity values were x = 0.165 and y = 0.120.

Example 11 A phosphor (Example 11) was obtained by using the CaWO ₄ phosphor of Comparative Example 2 as a raw material, supplying it into high frequency thermal plasma, and melting and quenching. The diameter of the plasma generator surrounding cylinder is 40 mm, the plasma gas is argon 55 l / min, oxygen is 20 l / min, the carrier gas is argon 10 l / min, and the cooling gas is argon 30.
l / min, power supply output is E _P = 10.0 kV, I _P =
It was 1.2 A and the average temperature of the plasma was 2500 ° C. The raw material supply rate was 25 g / min. The average particle size of the obtained phosphor was 3.9 μm as measured by the Blaine method. An electron micrograph of the obtained phosphor is shown in FIG. The ratio of the major axis to the minor axis of each phosphor particle obtained from this electron micrograph is 1.00 to 1.08.
Was in the range. The same phosphor of 0.2 μm or less generated by partial evaporation of the raw material particles adheres to the particle surface of the obtained phosphor, but after the ultrasonic cleaning, the supernatant liquid is discarded to A phosphor containing 0.1% by weight of ultrafine particles of 0.2 μm or less was obtained. It was also confirmed that the X-ray diffraction pattern of this phosphor was that of CaWO ₄ .

When the emission spectrum of this phosphor was measured by ultraviolet or electron beam excitation, the peak wavelength was 433 nm, which was 20 nm or more longer than the spectrum of the phosphor of Comparative Example 2 on the long wavelength side. Therefore, the chromaticity values were x = 0.173 and y = 1.44. When this phosphor was excited by ultraviolet rays of 254 nm to measure the powder brightness, it was 78% with respect to the phosphor of Comparative Example 2. Further, when the powder luminance was measured by exciting this phosphor with an electron beam having an accelerating voltage of 10 kV and a current density of 0.5 μA / cm ² , it was about 102% with respect to the phosphor of Comparative Example 2.

Then, a precipitation method is carried out using this phosphor.
When a fluorescent film having a coating amount of 10 mg / cm ² was formed and the transmittance was measured, a light transmittance 1.7 times that of the fluorescent film formed using the phosphor of Comparative Example 2 was obtained.

Using the obtained phosphor, a phosphor screen having a coating amount of 6 mg / cm ² was formed by a sedimentation method, and after applying an aluminum back, an electron gun was attached, exhausted and sealed, and a 7-inch cathode wire was attached. A tube was made. About this cathode ray tube, acceleration voltage 3
When the luminance was measured under the conditions of 0 kV and a beam current of 500 μA, it was 118% with respect to the cathode ray tube similarly produced using the phosphor of Comparative Example 2.

Comparative Example 3 A CaWO ₄ : Pb phosphor (Comparative Example 3) was produced by a conventional wet precipitation / calcination method.
The average particle size of this phosphor measured by the Blaine method is 3.
It was 6 μm. The peak wavelength of the emission spectrum of this phosphor excited by ultraviolet rays or electrons was 435 nm. The chromaticity values were x = 0.172 and y = 1.169. The peak wavelength of the excitation spectrum was located at 270 nm.

Example 12 CaWO ₄ : P of Comparative Example 3
The phosphor (b) was used as a raw material, supplied into high-frequency thermal plasma, and melted and quenched to obtain a phosphor (Example 12).
Plasma generating outer囲円barrel diameter 40 mm, the plasma gas is argon 55l / min, oxygen 20l / min, carrier gas argon 10l / min, the cooling gas is argon 30l / min, power supply output E _P = 10.0 kV, I
_P = 1.2A, average plasma temperature is 2500 ° C
Met. The raw material supply rate was 20 g / min. The average particle size of the obtained phosphor was 3.1 μm as measured by the Blaine method. The ratio of the major axis to the minor axis of each phosphor particle obtained from the electron micrograph was in the range of 1.00 to 1.11. The resulting phosphor is ultrasonically washed and the supernatant is discarded to obtain 0.2 μm.
A phosphor containing 0.05% by weight of ultrafine particles of m or less was obtained. The X-ray diffraction pattern of this phosphor is CaWO
₄ : confirmed to be Pb.

When the emission spectrum of this phosphor was measured by ultraviolet or electron beam excitation, the peak wavelength was 458 nm and the chromaticity values were x = 0.180 and y =.
It was 0.186. The excitation spectrum is 259n
m, and the deviation from 254 nm was slight. When this phosphor was excited by ultraviolet rays of 254 nm and the powder brightness was measured, it was 105% with respect to the phosphor of Comparative Example 3. Further, when this phosphor was excited with an electron beam having an accelerating voltage of 10 kV and a current density of 0.5 μA / cm ² , the powder brightness was measured and found to be about 103% of that of the phosphor of Comparative Example 2.

Next, by using this phosphor, a sedimentation method is carried out.
When a fluorescent film having a coating amount of 9 mg / cm ² was formed and the transmittance was measured, a light transmittance that was 1.8 times that of the fluorescent film formed using the phosphor of Comparative Example 3 was obtained.

Comparative Example 4 A MgWO ₄ phosphor (Comparative Example 4) was manufactured by a conventional wet precipitation / calcination method. The average particle size of this phosphor measured by the Blaine method was 4.2 μm. The peak wavelength of the emission spectrum of this phosphor excited by ultraviolet rays or electron beams was 498 nm. The chromaticity values were x = 0.225 and y = 0.418.

Example 13 A phosphor (Example 13) was obtained by using the MgWO ₄ phosphor of Comparative Example 4 as a raw material, supplying it into high-frequency thermal plasma, and melting and quenching. The diameter of the plasma generator surrounding cylinder is 40 mm, the plasma gas is argon 55 l / min, oxygen is 20 l / min, the carrier gas is argon 10 l / min, and the cooling gas is argon 30.
l / min, power supply output is E _P = 10.0 kV, I _P =
It was 1.3 A and the average temperature of the plasma was 2700 ° C. The raw material supply rate was 20 g / min. The average particle diameter of the obtained phosphor was 4.0 μm as measured by the Blaine method. Further, the ratio of the major axis to the minor axis of each phosphor particle obtained from the electron micrograph is 1.00.
Was in the range of ˜1.07. The obtained phosphor was ultrasonically washed and the supernatant was discarded to obtain a phosphor containing 0.2% by weight of ultrafine particles of 0.2 μm or less. It was also confirmed that the X-ray diffraction pattern of this phosphor was that of MgWO ₄ .

When the emission spectrum of this phosphor was measured by ultraviolet or electron beam excitation, the peak wavelength was 512 nm, and the chromaticity values were x = 0.233, y =
It was 0.441. The excitation spectrum is 254n
It was deviated to the shorter wavelength side than m. 254n this phosphor
When the powder luminance was measured by exciting with ultraviolet rays of m, it was 114% with respect to the phosphor of Comparative Example 4. In addition, this phosphor was used with an acceleration voltage of 10 kV and a current density of 0.5 μA / cm ^2.
When the powder luminance was measured by exciting with the electron beam of No. 3, it was about 109% with respect to the phosphor of Comparative Example 4. in this way,
Compared to the phosphor of Comparative Example 4, the phosphor of Example 13 has a larger absorption spectrum when excited by ultraviolet light and a higher luminous efficiency than the phosphor of Comparative Example 4 because the excitation spectrum shifts to the shorter wavelength side.

Next, by using this phosphor, a sedimentation method is carried out.
When a fluorescent film having a coating amount of 12 mg / cm ² was formed and the transmittance was measured, a light transmittance of 1.5 times that of the fluorescent film formed using the phosphor of Comparative Example 4 was obtained.

Using the obtained phosphor, a phosphor screen having a coating amount of 6 mg / cm ² was formed by a precipitation method, and after applying an aluminum back, an electron gun was attached, exhausted and sealed, and a 7-inch cathode wire was attached. A tube was made. About this cathode ray tube, acceleration voltage 3
When the luminance was measured under the conditions of 0 kV and a beam current of 500 μA, it was 115% with respect to the cathode ray tube similarly produced using the phosphor of Comparative Example 4.

[0072]

As described in detail above, since the phosphor produced by the method of the present invention has a small particle size and a shape close to a true sphere, it is possible to form a dense and uniform phosphor screen.
Consequently, it is possible to obtain a cathode ray tube or a fluorescent lamp with high brightness.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of a manufacturing apparatus used to carry out the method of the present invention.

FIG. 2 is a conceptual diagram showing a temperature distribution of a thermal plasma flame.

FIG. 3 is a conceptual diagram showing thermal plasma temperature and axial position.

FIG. 4 is an electron micrograph showing the particle structure of the phosphor in Example 1 of the present invention.

FIG. 5 is an electron micrograph showing the particle structure of the phosphor in Example 4 of the present invention.

FIG. 6 is an electron micrograph showing the particle structure of the phosphor in Example 7 of the present invention.

FIG. 7 is an electron micrograph showing the particle structure of the phosphor in Example 8 of the present invention.

FIG. 8 is an electron micrograph showing the particle structure of the phosphor of Example 11 of the present invention.

[Explanation of symbols]

10 ... Plasma gas, 11 ... Powder supply device, 12 ... Carrier gas supply cylinder, 13 ... Powder supply port, 14 ... High frequency oscillator, 15 ... Coil, 16 ... Plasma frame, 17 ...
Reaction vessel, 18 ... Cyclone, 19 ... Plasma generation part surrounding cylinder, 20 ... Cooling gas source.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Naoshihisa Matsuda, 1 Komukai Toshiba-cho, Sachi-ku, Kawasaki City, Kanagawa Prefecture, Research & Development Center, Toshiba Corporation (72) Miwa Okumura, Komukai-Toshiba, Kawasaki-shi, Kanagawa Prefecture Town No. 1 Incorporated company Toshiba R & D Center (72) Inventor Shinjiro Motoki 5893 Tamura, Hiratsuka-shi, Kanagawa High frequency heat-smelting company Shonan Works (72) Inventor Kazuhiro Kawasaki 5893 Tamura, Hiratsuka-shi, Kanagawa (72) Inventor, Seiji Yokota Stock Company 5893 Tamura, Hiratsuka-shi, Kanagawa High frequency smelting Co., Ltd. Shonan Factory

Claims (11)

[Claims] 1. Ln ₂ O ₃ : R or Ln ₂ O ₂ S:
R (where Ln is at least one element selected from the group consisting of La, Gd, Lu and Y, R is at least one element selected from the lanthanide group), MWO ₄
(However, M is at least one of Ca and Mg)
Alternatively, in producing the phosphor represented by the composition formula of CaWO ₄ : Pb, the average temperature of plasma is 1600 ° C. or higher and 6 or more.
Argon, helium, krypton, neon, xenon, oxygen, nitrogen, hydrogen, or a mixed gas of two or more of these gases is used to maintain the temperature below 500 ° C. in a high temperature plasma in which the atmosphere and high frequency energy are controlled as required. And a spherical shape having an average particle size of 0.5 to 20 μm and a ratio of the major axis to the minor axis of each particle in the range of 1.0 to 1.5. 2. Ln ₂ O ₃ : R or Ln ₂ O ₂ S:
R (where Ln is at least one element selected from the group consisting of La, Gd, Lu and Y, R is at least one element selected from the lanthanide group), MWO ₄
(However, M is at least one of Ca and Mg)
Or CaWO _4: Upon manufacturing a phosphor represented by the composition formula of Pb, high frequency power supply output is 5～100KW, plasma gas flow rate 20～150L / min, carrier gas flow rate 5～50L / min, the plasma generator The inner diameter of the outer cylinder is 3
Treated in a high-temperature plasma generated under the condition of 0 to 100 mm to form a spherical shape having an average particle size of 0.5 to 20 μm and a ratio of the major axis to the minor axis of each particle in the range of 1.0 to 1.5. A method for producing a phosphor, comprising: 3. Ultrafine particles having a particle diameter of 0.2 μm or less are 0.0
The method for producing the phosphor according to claim 1, wherein the phosphor is contained in an amount of 01 to 5% by weight. 4. Ln ₂ O ₃ : R (where Ln is La,
In producing a phosphor represented by the composition formula of at least one element selected from the group consisting of Gd, Lu and Y, and R is at least one element selected from the lanthanide group, the average temperature of plasma Is 2500 ° C or higher 6500
Argon, helium, krypton,
Neon, xenon, oxygen, nitrogen, hydrogen or these 2
The mixture is treated in a high temperature plasma in which the atmosphere and the high frequency energy are controlled in a predetermined manner using a mixed gas of at least one kind, the average particle diameter is 0.5 to 15 μm, and the ratio of the major axis to the minor axis of each particle is 1. The method for producing a phosphor according to claim 1, wherein the phosphor has a spherical shape in the range of 0 to 1.5. 5. An ultrafine particle having a particle diameter of 0.2 μm or less is 0.0
The method for producing a phosphor according to claim 4, wherein the phosphor contains 0 to 1% by weight. 6. Ln ₂ O ₂ S: R (where Ln is L
a, Gd, Lu and Y, at least one element selected from the group consisting of a, R is at least one element selected from the lanthanide group) in producing a phosphor represented by the composition formula Average temperature is over 2000 ℃ 65
Treatment in argon or helium, krypton, neon, xenon, oxygen, nitrogen, hydrogen or a mixed gas of two or more of these gases at a temperature of 00 ° C. or less in a high temperature plasma in which the atmosphere and high frequency energy are controlled as required. The fluorescent particles according to claim 1 or 2, wherein the spherical particles have an average particle diameter of 0.5 to 15 µm and a ratio of the major axis to the minor axis of each particle is in the range of 1.0 to 1.5. Body manufacturing method. 7. An ultrafine particle having a particle diameter of 0.2 μm or less is 0.0
The method for producing the phosphor according to claim 6, wherein the phosphor contains 0.1 to 0.5% by weight. 8. MWO ₄ (where M is Ca and Mg)
At least one of the above) or CaWO ₄ : Pb, in producing the phosphor represented by the composition formula, argon, helium, krypton, neon, xenon, so that the average temperature of plasma is 1600 ° C. or higher and 5500 ° C. or lower. Oxygen, nitrogen, hydrogen, or a mixed gas of two or more of these is used to perform treatment in high-temperature plasma in which the atmosphere and high-frequency energy are controlled as desired, and the average particle size is 0.5 to 20.
μm, the ratio of the major axis to the minor axis of each particle is 1.0 to 1.5
The spherical shape in the range of 1 or 2.
A method for producing the described phosphor. 9. An ultrafine particle having a particle diameter of 0.2 μm or less is 0.0
The method for producing the phosphor according to claim 8, wherein the phosphor is contained in an amount of 01 to 5% by weight. 10. The method according to claim 1, wherein the activator concentration of the raw material phosphor is set to be different from the activator concentration after the thermal plasma treatment. 11. 600 after treatment in high temperature plasma
The method according to claim 1 or 2, wherein the firing is performed at 1300 ° C.