JP4525241B2 - Phosphor, manufacturing method thereof, and plasma display panel - Google Patents

Description

  The present invention relates to a phosphor, a manufacturing method thereof, and a plasma display panel, and more particularly to a phosphor containing Si and Zn, a manufacturing method thereof, and a plasma display panel.

  In recent years, a plasma display panel has attracted attention as a flat panel display that can replace a cathode ray tube (CRT) because the screen can be enlarged and thinned.

  The plasma display panel has two glass substrates provided with electrodes and a large number of minute discharge spaces (hereinafter referred to as cells) formed by partition walls provided between the substrates. A phosphor layer is provided on the inner wall of the cell, and a discharge gas mainly containing Xe or the like is enclosed. When a voltage is applied between the electrodes to selectively discharge cells regularly arranged on the substrate, ultraviolet rays are generated due to the discharge gas, which excites the phosphor and emits visible light. ing.

  For this reason, the phosphor used in the plasma display panel is called a vacuum ultraviolet ray-excited phosphor, and is generally manufactured by a solid phase method, and its average particle size is 2 to 10 μm. In the solid phase method, a precursor forming step of mixing a predetermined amount of a compound containing an element constituting the phosphor matrix and a compound containing an activator element such as Eu or Mn is performed, followed by firing at a predetermined temperature. In this method, a phosphor is obtained by performing a firing step (primary firing step) to promote a reaction between solid phases.

  Currently, display panels such as plasma display panels are required to improve various characteristics such as brightness improvement and smooth moving image display. Patent Documents 1 and 2 disclose a method for manufacturing a phosphor for improving the light emission intensity, which is the light emission amount of the phosphor, for improving luminance. In the manufacturing method described in Patent Document 1, an annealing process is performed in which a so-called heat treatment is performed after a primary firing process through a pulverization process. In the manufacturing method described in Patent Document 2, an acid, an alkali, or the like is performed after the primary firing process. Chemical treatment is performed, followed by air firing.

  However, in order to further improve the luminance, a phosphor that not only has a high light emission intensity but also does not deteriorate, that is, a phosphor excellent in the light emission intensity maintenance rate that maintains a high light emission intensity is required. In general, it is known that as the particle size of the phosphor becomes smaller, the emission intensity maintenance ratio decreases extremely. Such deterioration of the phosphor over time is caused by ion collision (hereinafter referred to as ion sputtering). Two types of factors are considered, namely, deterioration due to vacuum ultraviolet light (hereinafter referred to as VUV).

In particular, Zn ₂ SiO ₄ : Mn ²⁺ , which is widely used as a green phosphor, has almost no deterioration due to VUV, but has been reported to have a large deterioration width due to ion sputtering (Non-patent Document 1). Deterioration due to ion sputtering is no longer a problem when improving various characteristics.
JP 2003-34788 A JP 2003-292950 A Technical Report of IEICEID 99-95, 2000-01

  However, when the pulverized phosphor is annealed as in the manufacturing method described in Patent Document 1, the generation of defect levels during the pulverization is suppressed by reducing the degree of aggregation of the phosphor, and the fluorescence is reduced. Although the luminous efficiency of the phosphor is improved by improving the quantum efficiency of the body, deterioration due to ion sputtering cannot be prevented. Alternatively, as in the manufacturing method described in Patent Document 2, when the chemical treatment is performed after the primary firing step and then the atmosphere is fired, the impurity layer or the unreacted layer on the surface of the phosphor obtained in the primary firing step is removed. Although the emission intensity of the phosphor is improved, deterioration due to ion sputtering cannot be prevented.

  Thus, in order to further improve various characteristics of the phosphor, it is indispensable to obtain a phosphor that prevents deterioration due to ion sputtering.

  An object of the present invention is to provide a phosphor excellent in sputtering resistance that prevents deterioration due to ion sputtering, a manufacturing method thereof, and a plasma display.

In order to solve the above problem, the invention according to claim 1
A precursor forming step of forming a precursor using a material containing Zn and Mn as a raw material;
A primary firing step of firing the precursor obtained in the precursor formation step to form a phosphor having a crystal structure of Zn ₂ SiO ₄ : Mn ²⁺ ;
An acid cleaning step for acid cleaning the phosphor obtained in the primary firing step;
An air firing step of firing the phosphor obtained in the acid washing step to the atmosphere;
A phosphor produced by subjecting the phosphor obtained by atmospheric firing to a reduction firing step for reduction firing,
The average particle size is 0.1 μm to 5 μm,
The maintenance ratio of the surface composition ratio of Zn when Si obtained by X-ray photoelectron spectroscopy is 1 is 60% or more before and after sputtering.

  According to the first aspect of the present invention, it is a phosphor having an average particle diameter of 0.1 μm to 5 μm, and the maintenance ratio of the surface composition ratio of Zn when Si is 1 determined by X-ray photoelectron spectroscopy is Since it is 60% or more before and after sputtering, the composition of Zn with respect to Si on the surface of the phosphor is not significantly changed before and after sputtering even in a phosphor having a small particle diameter having an average particle diameter of 0.1 to 5 μm.

The invention described in claim 2
The phosphor according to claim 1 is manufactured by a reactive crystallization method.

According to the invention described in claim 2 , since the phosphor according to claim 1 is manufactured by the reaction crystallization method, it is manufactured by the reaction crystallization method in which the emission intensity is particularly easy to be reduced as compared with the solid phase method. Even in this case, the Zn composition and light emission intensity on the phosphor surface are not significantly reduced before and after sputtering.

A plasma display panel according to a third aspect of the present invention comprises:
It is manufactured using Zn ₂ SiO ₄ : Mn ^{2+ according} to claim 1 or 2 .

According to the third aspect of the present invention, the plasma display panel is manufactured using the Zn ₂ SiO ₄ : Mn ²⁺ according to the first or second aspect. The Zn composition and emission intensity on the phosphor surface are not significantly reduced.

The invention according to claim 4
A precursor forming step of forming a precursor using a material containing Zn and Mn as a raw material ;
A primary firing step of firing the precursor obtained in the precursor formation step to form a phosphor having a crystal structure of Zn ₂ SiO ₄ : Mn ²⁺ ;
An acid cleaning step for acid cleaning the phosphor obtained in the primary firing step;
And air annealing step of air annealing the obtained the phosphor with an acid cleaning step,
A reduction firing step of reduction firing to the phosphor obtained in the atmospheric sintering,
It is a manufacturing method of the fluorescent substance containing this.
The invention described in claim 5
In the manufacturing method of the fluorescent substance according to claim 4,
In the precursor forming step, the precursor is formed by a reactive crystallization method.

According to the invention described in claim 4 , since the phosphor composition having a small particle size does not significantly reduce the Zn composition and light emission intensity before and after sputtering, the phosphor having a small particle size is used. Even in the manufactured plasma display panel, deterioration due to ion sputtering can be prevented.

According to the first aspect of the present invention, the composition of Zn with respect to Si on the phosphor surface is not significantly changed before and after sputtering even in a phosphor having a small particle size.
This means that the structure of the phosphor surface is not significantly affected by sputtering, and the phosphor having such characteristics has a uniform structure, thus preventing deterioration due to ion sputtering. Can do.

According to the second aspect of the present invention, the composition and emission intensity of Zn on the phosphor surface before and after sputtering, even if the phosphor is manufactured by a reaction crystallization method in which the emission intensity is easily reduced compared to the solid phase method. Can be prevented and deterioration due to ion sputtering can be prevented while maintaining the emission intensity.

According to the invention described in claim 3 , since the phosphor composition having a small particle size does not significantly reduce the Zn composition and emission intensity on the phosphor surface before and after sputtering, the phosphor having a small particle size is used. Even in the manufactured plasma display panel, deterioration due to ion sputtering can be prevented.

  The best mode for carrying out the present invention will be described below with reference to the drawings. However, the scope of the invention is not limited to the illustrated examples.

First, the phosphor according to the present invention will be described.
The phosphor of the present invention is a phosphor having a crystal structure of Zn and Si, and preferably having a crystal structure of Zn ₂ SiO ₄ : Mn ²⁺ .
In addition, the phosphor of the present invention has an average particle diameter of 0.1 to 5 μm, and the maintenance ratio of the surface composition ratio of Zn when Si obtained by X-ray photoelectron spectroscopy is 1 is 60% before and after sputtering. That's it.

  This is because the amount of Zn on the surface of the phosphor decreases before and after ion sputtering by performing surface composition analysis on the phosphor before and after ion sputtering by X-ray photoelectron spectroscopy. This is because it has been found that the emission intensity maintenance ratio increases when a panel is made using a phosphor with a small amount of change. In addition, the surface of the phosphor in the present invention is a region having a depth of about 2 to 5 nm from the outermost surface of the phosphor particles.

  Specifically, surface composition analysis was performed by X-ray photoelectron spectroscopy using VG Scientific ESCALab200R. At this time, the maintenance rate of Zn when the ratio of Si atoms on the phosphor surface was set to 1 was examined. Here, the maintenance rate of Zn is expressed by the following formula (1).

  Zn retention ratio = [(Zn composition ratio after ion sputtering) / (Zn composition ratio before ion sputtering)] × 100 (1)

  As a result, it has been clarified that the emission intensity maintenance ratio of the phosphor is remarkably improved when the Zn maintenance ratio is 60% or more before and after ion sputtering. When a plasma display panel is created using this phosphor, It was revealed that the luminous intensity maintenance rate of the plasma display panel was remarkably improved.

  In addition, the phosphor of the present invention has an average particle diameter of 0.1 to 5 μm, and a light emission intensity maintenance rate of 75% or more before and after sputtering.

  This is because the present inventors measured the emission intensity at the excitation wavelength of 146 nm of the phosphor before and after ion sputtering, thereby creating a plasma display panel using the phosphor with a small decrease in emission intensity before and after ion sputtering. Then, it is because it discovered that the luminous intensity maintenance factor of a plasma display panel became high.

  Specifically, ion sputtering was performed for 5 minutes under the conditions of an Ar gas atmosphere, a discharge voltage of 1.0 kV, a discharge current of 5 mA, and a discharge pressure of 13 Pa using an ion sputtering apparatus SC-701 manufactured by Sanyu Electronics. As a result, it has been clarified that when a plasma display panel is prepared using a phosphor having a luminous intensity maintenance rate of 75% or more before and after ion sputtering, the luminous intensity maintenance rate of the plasma display panel is remarkably improved. Here, the emission intensity maintenance rate is expressed by the following equation (2).

  Emission intensity maintenance factor = [(Emission intensity after ion sputtering) / (Emission intensity before ion sputtering)] × 100 (2)

  As a result, it has been clarified that when a plasma display panel is prepared using a phosphor having a luminous intensity maintenance rate of 75% or more before and after ion sputtering, the luminous intensity maintenance rate of the plasma display panel is remarkably improved.

  As described above, it was found that the issue intensity maintenance rate is clearly increased in the plasma display panel manufactured using the phosphor whose Zn maintenance rate and emission intensity maintenance rate on the phosphor surface exceed specific values before and after ion sputtering. In the present invention, it is possible to manufacture a plasma display panel with little luminance deterioration.

  Further, it has been conventionally known that the emission intensity maintenance rate in the plasma display panel is extremely lowered as the size of the phosphor is reduced. In particular, the tendency appears in the phosphor of 5 μm or less, and the tendency is remarkable in the phosphor of 2 μm or less. This is considered due to an increase in the specific surface area relative to the volume.

  Furthermore, the present inventors have found that the phosphor produced by the reaction crystallization method has a lower emission intensity maintenance rate in the plasma display panel than that produced by the solid phase method. This is because, in the reaction crystallization method, the phosphor structure is uniform at the atomic level at the phosphor precursor stage before firing, so that the uniform structure is maintained up to the outermost surface even after firing. The ratio is expected to be high.

  However, the present inventors have a Zn composition ratio (atm%) retention rate of 60 before and after ion sputtering even with such a small particle size phosphor or a phosphor produced by reactive crystallization. It has been found that the emission intensity maintenance rate of the plasma display panel is sufficiently high when the emission intensity maintenance ratio is 75% or more.

  In addition, as conventionally known, in the process of manufacturing a phosphor, the present inventors disperse the phosphor precursor after firing and perform acid cleaning, so that the emission intensity is adjusted before acid cleaning. It was confirmed that the increase was about 110% to 120%. Furthermore, the present inventors have found that a phosphor having high sputter resistance and high emission intensity can be obtained by firing in an air atmosphere after acid cleaning and subsequently firing in a reducing atmosphere.

This is assumed to be a result supporting the following theory.
By the acid cleaning treatment, the outermost surface of the phosphor becomes amorphous by dissolution with an acid. For this reason, the bond of Zn is broken by the energy of sputtering in vacuum, oxygen is evaporated from the surface, and in the phosphor subjected to the acid cleaning treatment, the sputtering resistance is deteriorated as compared with before the acid cleaning treatment.

  However, it has been clarified that the sputter resistance is remarkably improved by crystallizing the outermost surface which has been in an amorphous state by baking in an air atmosphere after acid cleaning and increasing the bonding of oxygen.

  Moreover, sputtering resistance was improved over phosphors before acid cleaning by performing atmospheric baking followed by reduction baking after acid cleaning. Further, when the phosphor not subjected to acid cleaning was baked in the air, the improvement in sputtering resistance was slight. In order to increase the oxygen bond on the outermost surface, it is considered that the surface must once be in an amorphous state by acid cleaning.

Further, when only the atmospheric firing is performed on the phosphor after acid cleaning, the emission intensity is low, and the improvement range of the sputter resistance is also small. This is because Mn ^2+, which is the luminescence center, is oxidized by air firing and does not contribute to light emission, and the crystal structure is unstable due to Mn ²⁺ in the Zn ²⁺ site becoming Mn ^3+. It seems that this is the cause.

However, by performing reduction firing, Mn ³⁺ becomes Mn ²⁺ , and the sputter resistance and the emission intensity are simultaneously improved.

  Hereinafter, a method for producing such a phosphor having excellent sputter resistance will be described. The phosphor according to the present invention includes a precursor forming step for forming a phosphor precursor, a primary firing step for firing the precursor obtained in the precursor forming step to form a phosphor, and a primary firing. An acid cleaning process in which the phosphor obtained in the process is subjected to acid cleaning, an air firing process in which the phosphor obtained in the acid cleaning process is fired in the atmosphere, and a reduction firing in which firing is performed in a reducing atmosphere following the air firing process. It is obtained by a manufacturing method including a process.

First, a precursor formation process is demonstrated.
In the precursor forming step, the precursor is preferably formed by a liquid phase method (also referred to as “liquid phase synthesis method”).

  The liquid phase method is a method for obtaining a phosphor by preparing a phosphor precursor in the presence of a liquid or in a liquid. In the liquid phase method, since the phosphor raw material is reacted in the liquid phase, the reaction is performed between element ions constituting the phosphor, and a stoichiometrically high purity phosphor is easily obtained. Compared with the solid phase method in which the phosphor is produced while repeating the solid phase reaction and the pulverization step, particles having a small particle size can be obtained without performing the pulverization step. It is possible to prevent lattice defects in the crystal and prevent a decrease in light emission efficiency.

  In the present invention, any crystallization method or coprecipitation method including conventionally known cooling crystallization can be used as the liquid phase method, but the reaction crystallization method is particularly preferable.

  The reactive crystallization method is a method for producing a phosphor precursor by mixing a raw material solution or a raw material gas containing an element that becomes a raw material of a phosphor in a liquid phase or a gas phase by utilizing a crystallization phenomenon. It is. Crystallization is a phenomenon in which the solid phase precipitates from the liquid phase when the physical or chemical environment changes due to cooling, evaporation, pH adjustment, concentration, etc., or when the state of the mixed system changes due to a chemical reaction. It refers to the phenomenon. The method for producing a phosphor precursor by the reactive crystallization method in the present invention means a production method by physical and chemical operations that can cause the occurrence of the crystallization phenomenon as described above.

  Any solvent may be used as the solvent for applying the reaction crystallization method as long as the reaction raw material dissolves, but water is preferable from the viewpoint of ease of supersaturation control. In the case of using a plurality of reaction raw materials, the addition order of the raw materials may be simultaneous or different, and an appropriate order can be appropriately assembled depending on the activity.

  In any process when preparing a precursor using the reaction crystallization method, it is preferable to control various physical properties such as the addition rate of the reaction raw material, the stirring speed, the temperature during the reaction, and the pH during the reaction. Ultrasonic waves may be irradiated. Further, a surfactant, a polymer or the like may be added for particle size control. Furthermore, after the addition of the raw material is completed, it is one of preferred embodiments to perform either one or both of concentration and aging as necessary.

  The phosphor precursor thus obtained is an intermediate product of the phosphor of the present invention, and it is preferable to obtain the phosphor by firing the phosphor precursor according to a predetermined temperature as described later. .

  After synthesizing the precursor by a liquid phase method, it is preferably recovered by a method such as filtration, evaporation to dryness, centrifugation, etc., if necessary, followed by washing and desalting.

  The desalting process is a process for removing impurities such as by-salts from the phosphor precursor. Various membrane separation methods, coagulation sedimentation methods, electrodialysis methods, methods using ion exchange resins, Nudelle washing methods, etc. are applied. can do.

  In the present invention, from the viewpoint of improving the productivity of the phosphor precursor and sufficiently removing the secondary salt and impurities to prevent the coarsening of the particles and the expansion of the particle size distribution, the electrical conduction after the desalting of the precursor is performed. The degree is preferably in the range of 0.01 mS / cm to 20 mS / cm, more preferably 0.01 to 10 mS / cm, and particularly preferably 0.01 mS / cm to 5 mS / cm.

  By adjusting the electric conductivity as described above, there is an effect in improving the light emission luminance of the finally obtained phosphor. Note that any method can be used for measuring the electrical conductivity, but a commercially available electrical conductivity measuring device may be used.

  After the desalting treatment step, a drying step may be further performed.

Next, the primary firing process will be described.
In the primary firing step, a phosphor is formed by firing the phosphor precursor obtained in the primary firing step.

  When firing the phosphor precursor, any method may be used, and the firing temperature and time may be adjusted so that the performance is the highest. For example, a phosphor having a desired composition can be obtained by firing in the atmosphere at a temperature between 600 ° C. and 1800 ° C. for an appropriate time. Also effective is a method in which baking is performed at 1100 ° C. for 90 minutes in the air after baking at about 800 ° C. to oxidize organic substances.

  As the baking apparatus (baking container), any apparatus known at present can be used. For example, a box furnace, a crucible furnace, a cylindrical tube type, a boat type, a rotary kiln and the like are preferably used. The atmosphere can also be selected as appropriate according to the precursor composition, such as oxidizing, reducing, or inert gas. Furthermore, you may give a reduction process or an oxidation process after baking as needed.

  Moreover, you may add a sintering inhibitor as needed at the time of baking. When a sintering inhibitor is added, it can be added as a slurry when the phosphor precursor is formed. Alternatively, a powdery material may be mixed with the dried precursor and fired.

The sintering inhibitor is not particularly limited, and is appropriately selected depending on the type of phosphor and firing conditions. For example, depending on the firing temperature range of the phosphor, a metal oxide such as TiO ₂ is used for baking at 800 ° C. or lower, SiO ₂ is used for baking at 1000 ° C. or lower, and Al ₂ O ₃ is used for baking at 1700 ° C. or lower. Are preferably used.

  Depending on the phosphor composition, reaction conditions, etc., for example, crystallization may progress in the drying step, and firing may not be necessary. In that case, the firing process may be omitted.

  After the firing treatment, various steps such as cooling treatment and dispersion treatment may be performed, or classification may be performed.

  In the cooling process, a process for cooling the fired product obtained by the firing process is performed. Although a cooling process is not specifically limited, It can select suitably from a well-known cooling method, for example, it can cool with this baked product being filled in the said baking apparatus. Further, the temperature may be lowered by being left, or the temperature may be forcibly lowered while controlling the temperature using a cooler.

  In the dispersion treatment step, a treatment for dispersing the fired product obtained in the firing treatment step is performed. As a dispersion processing method, for example, a medium such as a high-speed stirring impeller disperser, a colloid mill, a roller mill, a ball mill, a vibrating ball mill, an attritor mill, a planetary ball mill, or a sand mill is moved in the apparatus to collide and shear. Examples thereof include those that are atomized by both forces, dry type dispersers such as a cutter mill, a hammer mill, and a jet mill, an ultrasonic disperser, and a high-pressure homogenizer.

Next, the acid cleaning process will be described.
In the acid cleaning step, an acid cleaning treatment is performed on the phosphor obtained through the primary firing step. In the acid cleaning treatment, the surface containing impurities such as impurities on the phosphor surface and defects such as cracks due to dispersion treatment is etched. Detailed conditions of the acid cleaning treatment are described below.

  An acidic aqueous solution is used when the acid cleaning treatment is performed. The pH value is not particularly specified, but a pH of 1 or more and less than 3 is particularly preferable. When the acidic aqueous solution is less than pH 1, the phosphor body is damaged, and the emission intensity is reduced.

  The acidic aqueous solution is not particularly limited as long as it is acidic, but for example, hydrochloric acid, nitric acid, citric acid, acetic acid and the like are preferable.

  In addition, it is preferable after an acid washing process to perform a water washing process etc. and remove an acidic liquid.

Next, the atmospheric baking process will be described.
In the air firing step, the phosphor obtained in the acid cleaning step is fired in the air. Detailed conditions for atmospheric firing are described below.

The firing atmosphere in the air firing step uses air, but a mixed gas such as N ₂ —O ₂ may be used. When a mixed gas of N ₂ —O ₂ is used, O ₂ is preferably 2% to 40%, particularly preferably 5% to 20%. The baking temperature can be appropriately selected from 500 ° C to 1200 ° C, but is preferably 500 ° C or higher and 1000 ° C or lower, more preferably 500 ° C or higher and 800 ° C or lower. This is because, when the temperature exceeds 1200 ° C., the phosphor particles are fused, and when the temperature is lower than 500 ° C., the improvement in the sputter resistance is not observed even after the reduction firing.

Next, the reduction firing process will be described.
The reduction firing process is performed following the air firing process, and the phosphor is fired in a reducing atmosphere. The conditions for reduction firing are conditions that control the reducing atmosphere, firing time, and firing temperature so that the light emission intensity is the highest and the sputtering resistance is enhanced. It is possible to find out. For example, under conditions where preferable results can be obtained when the firing temperature is 500 ° C. or more and 700 ° C. or less, an N ₂ —H ₂ mixed gas is used, H ₂ is 0.3% to 2%, and the firing time is 3 hours or more. However, it is not particularly limited to this condition.

In addition, a preferred method for further increasing the sputtering resistance will be described below.
When firing the precursor, it is preferable to increase the firing temperature or lengthen the firing time.

  It is also preferable to introduce oxygen into the firing atmosphere. Oxygen introduction prevents oxygen defects and improves the deterioration due to sputtering.

It is also effective to reduce the amount of activator Mn ²⁺ , but since the effect of increasing the afterglow value due to the decrease in the amount of activator appears, consider depending on the desired performance It is necessary.

It is also effective to use a divalent metal ion such as Ca, Mg, or Ba as a coactivator. By adding the coactivator, not only deterioration due to sputtering is improved, but also an effect of shortening the afterglow value is obtained. As described above, if the amount of Mn ²⁺ is decreased while the afterglow value is kept short, it is more effective in improving the deterioration due to sputtering.

  Next, an embodiment of a plasma display panel according to the present invention will be described with reference to FIG. Plasma display panels can be broadly classified according to the structure and operation mode of the electrodes into a DC type that applies a DC voltage and an AC type that applies an AC voltage. FIG. An example of a schematic configuration of the display panel is shown.

A plasma display panel 1 shown in FIG. 1 includes a front plate 10 that is a substrate disposed on the display side and a back plate 20 that faces the front plate 10.
First, the front plate 10 will be described. The front plate 10 transmits visible light and displays various information on the substrate, and functions as a display screen of the plasma display panel 1. The front plate 10 includes a display electrode 11, a dielectric layer. 12, a protective layer 13 and the like are provided.

  A material that transmits visible light, such as soda lime glass (blue plate glass), can be preferably used as the front plate 10. The thickness of the front plate 10 is preferably in the range of 1 to 8 mm, more preferably 2 mm.

  A plurality of display electrodes 11 are provided on the surface of the front plate 10 facing the back plate 20 and are regularly arranged. The display electrode 11 includes a transparent electrode 11a and a bus electrode 11b, and has a structure in which a bus electrode 11b similarly formed in a strip shape is laminated on a transparent electrode 11a formed in a wide strip shape. The width of the bus electrode 11b is narrower than that of the transparent electrode 11a. The display electrode 11 is a set of two display electrodes 11 that are arranged to face each other with a predetermined discharge gap.

  A transparent electrode such as a nesa film can be used as the transparent electrode 11a, and the sheet resistance is preferably 100Ω or less. As a width | variety of the transparent electrode 11a, the range of 10-200 micrometers is preferable.

  The bus electrode 11b is for lowering the resistance, and can be formed by sputtering of Cr / Cu / Cr or the like. The width of the bus electrode 11b is preferably in the range of 5 to 50 μm.

  The dielectric layer 12 covers the entire surface of the front plate 10 on which the display electrodes 11 are arranged. The dielectric layer 12 can be formed of a dielectric material such as low-melting glass. The thickness of the dielectric layer 12 is preferably in the range of 20 to 30 μm. The surface of the dielectric layer 12 is entirely covered with the protective layer 13. The protective layer 13 can use an MgO film. As thickness of the protective layer 13, the range of 0.5-50 micrometers is preferable.

Next, the back plate 20 will be described.
The back plate 20 is provided with address electrodes 21, dielectric layers 22, partition walls 30, phosphor layers 35R, 35G, and 35B.

  As the back plate 20, soda lime glass or the like can be used similarly to the front plate 10. As thickness of the backplate 20, the range of 1-8 mm is preferable, More preferably, it is about 2 mm.

  A plurality of address electrodes 21 are provided on the surface of the back plate 20 facing the front plate 20. The address electrode 21 is also formed in a strip shape like the transparent electrode 11a and the bus electrode 11b. A plurality of address electrodes 21 are provided at predetermined intervals so as to be orthogonal to the display electrodes 11 in plan view.

  The address electrode 21 can be a metal electrode such as an Ag thick film electrode. The width of the address electrode 21 is preferably in the range of 100 to 200 μm.

  The dielectric layer 22 covers the entire surface of the back plate 20 on which the address electrodes 21 are disposed. The dielectric layer 22 can be formed of a dielectric material such as low melting glass. The thickness of the dielectric layer 22 is preferably in the range of 20 to 30 μm.

  On both sides of the address electrode 21 on the dielectric layer 22, elongated partition walls 30 are erected from the back plate 20 side to the front plate 10 side. Orthogonal. Further, the partition wall 30 forms a plurality of micro discharge spaces (hereinafter referred to as discharge cells) 31 in which the back plate 20 and the front plate 10 are partitioned in a stripe shape. A discharge gas mainly composed of a rare gas is enclosed.

  In addition, the partition 30 can be formed from dielectric materials, such as low melting glass. The width of the partition wall 30 is preferably in the range of 10 to 500 μm, and more preferably about 100 μm. The height (thickness) of the partition wall 30 is usually in the range of 10 to 100 μm, and preferably about 50 μm.

  In the discharge cell 31, any of phosphor layers 35R, 35G, and 35B composed of phosphors emitting light of red (R), green (G), or blue (B) is provided in a regular order. Yes. In one discharge cell 31, there are many points where the display electrode 11 and the address electrode 21 intersect in a plan view, and each of these points of intersection is the smallest light emitting unit, and is continuous in the left-right direction. One pixel is composed of three light emitting units of R, G, and B. The thickness of each phosphor layer 35R, 35G, 35B is not particularly limited, but is preferably in the range of 5 to 50 μm.

  In forming the phosphor layer 35G, the phosphor of the present invention produced by the above-described method is dispersed in a mixture of a binder, a solvent, a dispersant and the like, and a phosphor paste adjusted to an appropriate viscosity is used as the discharge cell 31. The phosphor layer 35G in which the phosphor of the present invention is attached to the partition wall side surface 30a and the bottom surface 30a is formed by coating or filling the substrate, followed by drying or baking. The phosphor paste can be adjusted by a conventionally known method. Further, the phosphor content in the phosphor paste is preferably in the range of 30% by mass to 60% by mass.

  When the phosphor paste is applied or filled into the discharge cells 31R, 31G, and 31B, various methods such as a screen printing method, a photoresist film method, and an ink jet method can be used.

  On the other hand, in forming the phosphor layers 35R and 35B, red and blue phosphors and phosphor pastes manufactured by a conventionally known method are prepared, and the side walls of the barrier ribs are formed in the same manner as when the phosphor layer 35G is formed. It is assumed that phosphor layers 35R and 35B having red and blue phosphors attached to 30a and the bottom surface 30a are formed.

  By configuring the plasma display panel in this way, a trigger discharge is selectively performed between the address electrode 21 and one of the pair of display electrodes 11 and 11 during display. As a result, the discharge cell to be displayed is selected. Thereafter, a sustain discharge is performed between the pair of display electrodes 11 and 11 in the selected discharge cell, thereby generating ultraviolet rays caused by the discharge gas, and generating visible light from the phosphor layers 35R, 35G, and 35B. Make it possible.

  From the above, in the present invention, the phosphor is subjected to an acid cleaning step, and impurities on the surface of the phosphor and defective portions generated in the manufacturing process are removed by etching. Thereafter, air firing is performed, and the amorphous state of the phosphor surface generated in the acid cleaning step is crystallized again, so that oxygen bonds are increased on the phosphor surface as compared with the case where the acid cleaning step is not performed. Thereafter, reduction firing is performed so that Mn that becomes the emission center of the phosphor surface can be made to be bivalent, which contributes to light emission, and a phosphor obtained by a conventional simple heat treatment process and a phosphor that only performs air firing after acid cleaning In comparison with this, the emission intensity and emission intensity maintenance ratio can be further increased before and after sputtering, and deterioration due to ion sputtering can be prevented.

  In addition, by using the phosphor manufactured by the phosphor manufacturing method according to the present invention for a plasma display, oxygen bonding on the phosphor surface can be increased and Mn on the phosphor surface can be divalent. The plasma display panel 1 can further improve various characteristics as described above.

  Hereinafter, although Example 1 and Example 2 which concern on this invention are demonstrated, this invention is not limited to this.

[Example 1]
In Example 1, phosphors 1 to 3 having a crystal structure of Zn ₂ SiO ₄ : Mn ²⁺ are produced as green phosphors, and the obtained phosphor particles are subjected to sputtering treatment, and relative light emission before and after the sputtering treatment is performed. The strength was evaluated. First, synthesis of phosphors 1 to 3 will be described.

1. Preparation of phosphor (1) Preparation of phosphor 1 After thoroughly mixing 7.32 g of zinc oxide, 0.7 g of manganese oxide and 6 g of silicon oxide in a mortar, firing at 1280 ° C. for 3 hours in an atmosphere of 100% nitrogen. And phosphor 1 was obtained. The obtained phosphor was dispersed using a ball mill. After the dispersion, phosphor 1 was washed with an acid. In the acid washing, 5 g of phosphor was added per 100 cc of hydrochloric acid 0.1 N, and after sufficient stirring, filtration and washing with pure water were performed.

After the acid cleaning, the phosphor was divided into two, and one was designated as phosphor 1-1. The other was fired at 500 ° C. for 3 hours in an air atmosphere, and then fired at 600 ° C. for 1 hour in an N ₂ 99% -H ₂ 1% atmosphere. This phosphor was designated as phosphor 1-2.

  After dispersion, the particle size distribution of the phosphor 1 was measured using a particle size distribution measuring device (LMS-300 manufactured by Seishin Enterprise Co., Ltd.), and the average particle size was determined. The average particle diameter of the phosphor 1 was 2.5 μm.

(2) Production of phosphor 2 Let 1000 cc of pure water be the A liquid. Kanto Chemical Co., Ltd. Zinc nitrate hexahydrate 36.26g and manganese nitrate hexahydrate 0.90g are melt | dissolved in a pure water, and it is set as 500 cc, and this is set as B liquid. 18.25 g of 28% ammonia water manufactured by Kanto Chemical Co., Ltd. is mixed with pure water and 18.78 g of a colloidal silica PL-3 35 nm 20% aqueous solution manufactured by Fuso Chemical Co., Ltd. to make 500 cc.

  While the liquid A was vigorously stirred at room temperature, the liquid B and the liquid C were added at a constant rate over 30 minutes to obtain a white precipitate. Thereafter, solid-liquid separation was performed by pressure filtration.

  Next, the collected precipitate was dried at 100 ° C. for 24 hours, and a dried precursor was obtained. The obtained precursor was baked at 1260 ° C. for 3 hours in an atmosphere of 100% nitrogen to obtain phosphor 2.

  The phosphor 2 was dispersed in the same manner as the phosphor 1 obtained by the production of (1) phosphor 1 described above.

  After the dispersion, phosphor 2 was washed with an acid. In the acid washing, 5 g of phosphor was added per 100 cc of hydrochloric acid 0.1 N, and after sufficient stirring, filtration and washing with pure water were performed.

After the acid washing, the phosphor was divided into two, and one was designated as phosphor 2-1. The other was fired at 500 ° C. for 3 hours in an air atmosphere, and then fired at 600 ° C. for 1 hour in an N ₂ 99% -H ₂ 1% atmosphere. This phosphor was designated as phosphor 2-2.

  After dispersion, the particle size distribution of phosphor 2 was measured in the same manner as phosphor 1, and the average particle size was determined. The average particle size of phosphor 2 was 4 μm.

(3) Production of phosphor 3 A phosphor 3 was obtained in the same manner as the phosphor 2 except that the firing temperature was 1200 ° C.
The phosphor 3 was dispersed in the same manner as the phosphors 1 and 2 obtained in (1) Preparation of the phosphor 1 and (2) Preparation of the phosphor 2.

After dispersion, the phosphor 3 was divided into five equal parts, and the following treatment was performed to prepare phosphors 3-1 to 3-5.
Phosphor 3-1: Untreated phosphor 3 was designated as phosphor 3-1.
Phosphor 3-2: Phosphor 3 was acid washed. Washing was performed by adding 5 g of phosphor per 0.1 cc of hydrochloric acid and stirring sufficiently, followed by filtration and washing with pure water.
Phosphor 3-3: Acid cleaning was performed in the same manner as phosphor 3-2. Thereafter, firing was performed at 500 ° C. for 3 hours in an air atmosphere.
Phosphor 3-4: In the same manner as Phosphor 3-3, acid cleaning and firing in air were performed. Thereafter, firing was performed in an atmosphere of 600 ° C. N ₂ 99.5% -H ₂ 0.5% for 1 hr.
Phosphor 3-5: Phosphor 3 was baked at 500 ° C. for 3 hours in an air atmosphere. Thereafter, firing was performed in an atmosphere of 600 ° C. N ₂ 99.5% -H ₂ 0.5% for 1 hr.

  After dispersion, the particle size distribution of phosphor 3 was measured in the same manner as phosphors 1 and 2, and the average particle size was determined. The average particle diameter of the phosphor 3 was 1.2 μm.

2. Measurement of emission intensity The emission intensity of the phosphors 1 to 3 obtained above was measured.
Measurement of the emission intensity was performed by irradiating ultraviolet rays using an excimer 146 nm lamp (manufactured by USHIO INC.) In a vacuum chamber of 0.1 to 1.5 Pa to emit green light from the phosphor. Next, the intensity | strength was measured for the obtained green light using the detector (MCPD-3000 (made by Otsuka Electronics Co., Ltd.)). The peak intensity of light emission was obtained as a relative value for phosphors 1-1 and 1-2 with phosphor 1-1 as 100. Similarly, phosphors 2-1 and 2-2 were obtained as relative values with respect to phosphor 2-1, and phosphors 3-1 to 3-5 as phosphor 3-2.

  Further, using an ion sputtering apparatus SC-701 manufactured by Sanyu Electronics Co., Ltd., sputtering was performed for 5 minutes in an Ar gas atmosphere under a discharge voltage of 1.2 kV, a discharge current of 5 mA, and a vacuum degree of 13 Pa.

  The surface composition of the phosphor before sputtering and the phosphor after sputtering was analyzed by X-ray photoelectron spectroscopy using ESCALab200R manufactured by VGS Scientific. The range that ESCALab200R measures is a region having a depth of about 2 to 5 nm from the outermost surface of the phosphor particles. From the element ratio (atm%) of the measured surface composition, the composition ratio of Zn when the value of Si is 1 is calculated. Furthermore, from the above formula (1), the maintenance rate of Zn was determined and the measurement results are shown in Table 1 below.

  Further, the emission intensity of the phosphor after sputtering was measured, the emission intensity maintenance rate was determined by the above equation (2), and the measurement results are shown in Table 1 below.

  As described above, with respect to the level at which the phosphor after the acid treatment is baked in the atmosphere, both the emission intensity maintenance rate and the Zn maintenance rate tend to improve, but are insufficient. Further, regarding the level after reduction firing, the emission intensity has recovered to the level before firing in the atmosphere, and it can be seen that both the emission intensity maintenance rate and the Zn maintenance rate have improved.

[Example 2]
In Example 2, a plasma display panel was manufactured using the phosphors 3-2 and 3-4 obtained in Example 1, and the emission intensity of the plasma display panel was evaluated. First, adjustment of the phosphor paste used for manufacturing the plasma display panel will be described.

1. Adjustment of phosphor paste (1) Adjustment of phosphor paste 1 As the phosphor paste according to the present invention, the phosphor 3-4 produced in Example 1 was used and mixed in the following composition. Adjustments were made.
Phosphor 3-4 45% by weight
1: 1 mixture of terpineol and pentanediol 54.5% by weight
Ethylcellulose (ethoxy group content 50%) 0.3% by weight
Polyoxyethylene alkyl ether 0.2% by weight
(2) Adjustment of phosphor paste of comparative example Phosphor paste 2 was adjusted in the same manner except that phosphor 3-4 of phosphor paste 1 was changed to phosphor 3-2, and phosphor paste of comparative example It was.

2. Manufacture of Plasma Display Panel (1) Manufacture of Plasma Display Panel 1 The AC surface discharge type plasma display panel 1 having the stripe cell structure shown in FIG. 1 was manufactured as follows.

  First, a transparent electrode is arranged as a transparent electrode 11a at a predetermined position on the glass substrate that will be the front plate 10. Next, the bus electrode 11b is formed on the transparent electrode 11a by sputtering Cr—Cu—Cr and performing photoetching, and the display electrode 11 is formed. Then, a low-melting glass is printed on the surface glass substrate 10 so as to cover the display electrodes 11 and is baked at 500 to 600 ° C. to form the dielectric layer 12. Further, a protective film 13 is formed on the dielectric layer 12 by electron beam evaporation of MgO.

  On the other hand, the address electrode 21 is formed on the back plate 20 by printing an Ag thick film and baking it. Then, partition walls 30 are formed on the back plate 20 and on both sides of the address electrodes 21. The partition walls 30 can be formed by printing low-melting glass with a pitch of 0.2 mm and baking. Further, the phosphor paste 1 and the separately prepared red phosphor paste and blue phosphor paste were applied to the discharge cells 31 partitioned by the barrier ribs 30 by a screen coating method. At this time, one color phosphor paste is used for each discharge cell 31. Thereafter, the phosphor paste was dried or baked to remove organic components in the paste, and phosphor layers 35R, 35G, and 35B having different emission colors were formed in the discharge cells 31R, 31G, and 31B, respectively.

  Then, the front plate 10 and the back plate 20 on which the electrodes 11, 21, etc. are arranged are aligned so that the respective electrode arrangement surfaces face each other, and the periphery is sealed while maintaining a gap of about 1 mm. Sealed with glass (not shown). A gas mixed with xenon (Xe) that generates ultraviolet rays by discharge and neon (Ne) as a main discharge gas is sealed between the substrates 10 and 20 and hermetically sealed, and then aging is performed. The plasma display panel was manufactured as described above, and the plasma display panel 1 was obtained.

(2) Manufacture of the plasma display panel of a comparative example The plasma display panel 2 of the comparative example was produced by making the said green fluorescent substance paste 1 into the fluorescent substance paste 2 as a plasma display panel of a comparative example.

3. Panel emission intensity of plasma display panel Next, for the plasma display panel 1 and the plasma display panel 2, the emission intensity immediately after the plasma display panel was turned on was measured. The results are shown in Table 2. The emission intensity is measured by measuring the white luminance when an equal sustain voltage (170 V AC voltage) is applied to the electrodes, and the emission intensity of the plasma display panel 2 is 100. The relative luminescence intensity was determined.
In addition, the emission intensity at 1000 hours after lighting was measured to determine the emission intensity maintenance rate.

  Thus, it can be seen that a phosphor having a high emission intensity maintenance rate after sputtering and a high Zn maintenance rate has a small deterioration width in the panel.

It is the perspective view which showed an example of the plasma display panel which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Plasma display panel 10 Substrate 20 Substrate 30 Partition wall 31R, 31G, 31B Discharge cell 35R, 35G, 35B Phosphor layer

Claims (5)

A precursor forming step of forming a precursor using a material containing Zn and Mn as a raw material;
A primary firing step of firing the precursor obtained in the precursor formation step to form a phosphor having a crystal structure of Zn ₂ SiO ₄ : Mn ²⁺ ;
An acid cleaning step for acid cleaning the phosphor obtained in the primary firing step;
An air firing step of firing the phosphor obtained in the acid washing step to the atmosphere;
A phosphor produced by subjecting the phosphor obtained by atmospheric firing to a reduction firing step for reduction firing,
The average particle size is 0.1 μm to 5 μm,
A phosphor characterized in that the maintenance ratio of the surface composition ratio of Zn when Si determined by X-ray photoelectron spectroscopy is 1 is 60% or more before and after sputtering. The phosphor according to claim 1 , wherein the precursor is formed by a reaction crystallization method. A plasma display panel comprising the phosphor according to claim 1 or 2 in a discharge cell. A precursor forming step of forming a precursor using a material containing Zn and Mn as a raw material ;
A primary firing step of firing the precursor obtained in the precursor formation step to form a phosphor having a crystal structure of Zn ₂ SiO ₄ : Mn ²⁺ ;
An acid cleaning step for acid cleaning the phosphor obtained in the primary firing step;
And air annealing step of air annealing the obtained the phosphor with an acid cleaning step,
A reduction firing step of reduction firing to the phosphor obtained in the atmospheric sintering,
A method for producing a phosphor, comprising: In the manufacturing method of the fluorescent substance according to claim 4,
In the precursor forming step, the precursor is formed by a reaction crystallization method.

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