JP2006083296A - Method for producing fluorescent substance, fluorescent substance and plasma display panel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a fluorescent substance by which the deterioration caused by ion sputtering is prevented while improving emission luminance; to provide the fluorescent substance; and to provide a plasma display panel. <P>SOLUTION: The method for producing the fluorescent substance is constituted of a precursor-forming step for forming a precursor of the fluorescent substance, a firing step for forming the fluorescent substance by firing the precursor obtained in the precursor-forming step, an acid-cleaning step for cleaning the fluorescent substance obtained in the firing step with an acid, and a top coat-forming step for forming a top coat comprising an alkali metal-based fluoride on the surface of the fluorescent substance obtained in the acid-cleaning step. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a phosphor manufacturing method, a phosphor, and a plasma display panel, and more particularly to a phosphor manufacturing method, a phosphor, and a plasma display panel on which a protective film is formed.

  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. 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 to promote a reaction between solid phases.

  By the way, in such a plasma display panel, there is a demand in the market for a phosphor that has not only high emission luminance but also excellent emission luminance maintenance ratio that can maintain high emission luminance.

Such deterioration over time of phosphors includes two types of factors: deterioration due to ion collision (hereinafter referred to as ion sputtering) and deterioration due to vacuum ultraviolet light (hereinafter referred to as VUV). In particular, it is reported that Zn ₂ SiO ₄ : Mn ²⁺ , which is known as a green phosphor, has a large deterioration width due to ion sputtering (Non-patent Document 1).

Conventionally, a method of providing a protective film on the surface of a phosphor is known in order to prevent deterioration due to ion sputtering (Patent Document 1). In Patent Document 1, a protective film is formed using an alkaline earth metal fluoride having a high transmittance with respect to a wavelength region near 147 to 172 nm, which is a wavelength region of vacuum ultraviolet light that excites a phosphor, and Attempts have been made to prevent deterioration due to ion sputtering while improving light emission luminance by efficient light reception.
JP 2001-200409 A Technical Report of IEICEID 99-95, 2000-01

  However, as in Patent Document 1, simply forming a protective film using an alkaline earth metal fluoride is not sufficient to improve the emission luminance and prevent deterioration due to ion sputtering. It was.

  The present invention has been made in view of the above problems, and a phosphor manufacturing method capable of preventing deterioration due to ion sputtering while improving emission luminance, and a fluorescence manufactured using such a manufacturing method. And a plasma display panel manufactured using the phosphor.

In order to solve the above problem, the invention according to claim 1
A precursor forming step for forming a precursor of the phosphor, a firing step for firing the precursor obtained in the precursor forming step to form a phosphor, and the phosphor obtained in the firing step. It includes an acid cleaning step for acid cleaning, and a protective film forming step for forming a protective film made of an alkali metal fluoride on the phosphor surface obtained in the acid cleaning step.

  According to invention of Claim 1, the precursor formation process which forms the precursor of fluorescent substance, the baking process which bakes the said precursor obtained at the said precursor formation process, and forms fluorescent substance, An acid cleaning step for acid cleaning the phosphor obtained in the firing step, and a protective film forming step for forming a protective film made of an alkali metal fluoride on the phosphor surface obtained in the acid cleaning step. As a result, the surface of the phosphor is formed after the phosphor surface is flattened by dissolving and removing the impurities on the phosphor surface in the acid cleaning step and the defective portion generated in the precursor forming step and the primary firing step. Thus, a protective film can be formed. Further, since the protective film is made of an alkali metal fluoride, it can transmit vacuum ultraviolet rays while protecting the phosphor, and does not hinder excitation of the phosphor.

The invention according to claim 2
2. The method of manufacturing a phosphor according to claim 1, further comprising an annealing step for annealing the phosphor obtained in the acid cleaning step after the acid cleaning step, and forming the protective film after the annealing step. A process is performed.

  According to the second aspect of the present invention, the method includes an annealing step for annealing the phosphor obtained in the acid cleaning step after the acid cleaning step, and the protective film forming step after the annealing step. Therefore, the layer formation can be performed in a state where the surface of the phosphor after the acid treatment step is smoother than the phosphor manufacturing method according to claim 1.

The invention described in claim 3
The method for producing a phosphor according to claim 1 or 2 is characterized in that the precursor forming step is a liquid phase method.

  According to the invention of claim 3, since the precursor forming step is a liquid phase method, the particles of the precursor obtained by the liquid phase method have uniform constituent elements at the atomic level, and the precursor particles are formed from the surface of the precursor. The composition can be uniform throughout.

The invention according to claim 4
The method for producing a phosphor according to any one of claims 1 to 3, wherein the phosphor has a crystal structure of Zn ₂ SiO ₄ : Mn ²⁺ .

According to the invention described in claim 4, wherein the phosphor is Zn ₂ Si0 _4: since the crystal structure of the Mn ^2+, in particular, deterioration width by ion sputtering is large Zn ₂ Si0 _4: The structure of Mn ²⁺ The phosphor having the same effect as any one of claims 1 to 3 can be obtained, and the protective film can be formed with the phosphor surface being flat.

The invention according to claim 5
It is the fluorescent substance manufactured with the manufacturing method as described in any one of Claims 1-4.

  According to the fifth aspect of the present invention, since the phosphor is manufactured by the manufacturing method according to any one of the first to fourth aspects, the phosphor is any one of the first to fourth aspects. The protective film can be formed in a state where the phosphor surface is flattened.

  According to a sixth aspect of the present invention, there is provided a plasma display panel including the phosphor according to the fifth aspect in a discharge cell.

  According to the invention described in claim 6, since the plasma display panel includes the phosphor according to claim 5 in a discharge cell, the plasma display panel can obtain the same operation as that of claim 5, A protective film can be formed on the surface of the phosphor with a well-aligned crystal plane.

  According to the first aspect of the present invention, after the phosphor surface is made flat by flattening the phosphor surface by dissolving and removing the impurities on the phosphor surface in the acid cleaning step and the defective portion generated in the precursor forming step and the firing step, Since a protective film can be formed by forming a layer on the surface, a protective film can be formed on a phosphor surface with a well-crystallized surface, and on the phosphor surface with such an atomic arrangement. Since the grown protective film has high crystallinity, the transmittance of vacuum ultraviolet rays can be increased and deterioration due to ion sputtering can be prevented. Therefore, the protective film can transmit vacuum ultraviolet rays while protecting the phosphor.

According to the invention described in claim 2, since the phosphor can be formed in a state where the surface of the phosphor after the acid treatment step is smoother than the method for manufacturing the phosphor according to claim 1, A protective film can be formed on the phosphor surface with a more uniform crystal plane, and the crystallinity of the protective film can be further enhanced. Therefore, the protective film can further increase the transmittance of vacuum ultraviolet rays and further prevent deterioration due to ion sputtering.
In addition, since the annealing process has an effect of increasing the crystallinity of the phosphor itself, it is possible to obtain a synergistic effect of improving the luminance of the phosphor itself and the deterioration resistance due to ion sputtering.

According to the invention described in claim 3, since the constituent elements of the precursor particles obtained by the liquid phase method are uniform at the atomic level and the composition can be uniform from the surface to the inside of the precursor, Compared with the phase method, the amount of SiO ₂ added to prevent the formation of Mn ₂ O ₃ during firing can be reduced, and the phosphor surface is not made SiO ₂ rich. Therefore, the protective film does not disturb the atomic arrangement on the phosphor surface, and the protective film can improve crystallinity and increase the transmittance of vacuum ultraviolet rays, and can further prevent deterioration due to ion sputtering.

According to the invention described in claim 4, in particular, in the phosphor having a structure of Zn ₂ SiO ₄ : Mn ²⁺ having a large deterioration width due to ion sputtering, it is the same as any one of claims 1 to 3. Since the protective film can be formed with the phosphor surface being flat, the protective film is formed on the phosphor surface with a well-aligned crystal surface to enhance the crystallinity of the protective film. Thus, it is possible to increase the transmittance of vacuum ultraviolet rays and to prevent deterioration due to ion sputtering.

  According to the invention described in claim 5, the phosphor can obtain the same effect as any one of claims 1 to 4, and the protective film is formed in a state where the surface of the phosphor is flattened. Therefore, it is possible to form a protective film on the surface of the phosphor with a uniform crystal surface to improve the crystallinity of the protective film to increase the transmittance of vacuum ultraviolet rays and to prevent deterioration due to ion sputtering.

  According to the sixth aspect of the present invention, the plasma display panel can obtain the same effect as that of the fifth aspect, and the protective film can be formed on the surface of the phosphor having a uniform crystal plane. The crystallinity of the film can be increased to increase the transmittance of vacuum ultraviolet rays, and 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, a method for manufacturing a phosphor according to the present invention will be described.
The phosphor manufacturing method according to the present invention includes a precursor forming step for forming a precursor of the phosphor, a firing step for firing the precursor obtained in the precursor forming step, and forming a phosphor, and a firing step. The phosphor obtained in (1) is subjected to an acid washing step, and a protective film forming step for forming a protective film on the phosphor surface obtained in the acid washing step.

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 materials is completed, it is also 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.

  Further, 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 firing process will be described.
In the firing step, a phosphor is formed by firing the phosphor precursor obtained in the precursor forming 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. Further, depending on the composition of the phosphor, reaction conditions, etc., it may not be necessary to perform firing, in which case the firing step may be omitted.

  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 baking treatment, prior to the acid washing step, 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 type 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 process is performed on the phosphor obtained through the 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. The impurities on the phosphor surface refer to unreacted substances that remain unreacted in the precursor formation step and the firing step, and a very small amount of substances other than the phosphors produced in these processes. The 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 main body is damaged and the light emission luminance 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. Moreover, it is preferable to perform an annealing process prior to the protective film forming process after the acid cleaning treatment.

Here, the annealing step will be described.
In the annealing step, reduction firing is subsequently performed after atmospheric firing is performed on the phosphor obtained in the acid cleaning step. First, detailed conditions for atmospheric firing will be described below.

As the firing atmosphere in the air firing, air is used, 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 10% to 30%. 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, detailed conditions for reduction firing will be described.
The conditions for reduction firing are conditions that control the reducing atmosphere, firing time, and firing temperature so that the luminance is highest and the sputtering resistance is high. It is possible to find out. For example, conditions under which favorable results are 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 1 hour or more and 3 hours or less. However, it is not particularly limited to this condition. Thus, by carrying out the reduction firing in succession to the atmospheric firing, the phosphor can improve the light emission luminance, and the crystallinity of the protective film can be increased when the protective film is formed.

Next, the protective film forming step will be described.
In the protective film forming step, a protective film is formed on the surface of the phosphor obtained in the acid cleaning step to prevent deterioration due to ion sputtering.

As a raw material for forming the protective film, it is necessary to use a phosphor that can efficiently receive vacuum ultraviolet rays. Therefore, an alkali metal fluoride having a high transmittance with respect to a wavelength region near 147 to 172 nm which is a wavelength region of vacuum ultraviolet rays is used. The alkali metal fluoride refers to a compound made of an alkali metal fluoride and an alkaline earth metal fluoride, and a compound made of a fluoride containing an element periodic table group Ia (excluding hydrogen) and group IIa. pointing. Among these, a compound made of any one of MgF ₂ , CaF ₂ , LiF or a combination thereof is preferable, and a compound made of MgF _{2 is} particularly preferable.

  As a method of forming the protective film, for example, a method of forming a protective film by mixing fine powder of magnesium fluoride and a phosphor, attaching them to the phosphor surface, and then baking, or dispersion of the phosphor Examples thereof include a method in which ammonium fluoride and magnesium chloride are simultaneously mixed in a liquid to deposit ammonium fluoride on the phosphor surface. When the alkali metal fluoride fine powder as described above is used, the particle diameter of the fine powder is preferably 300 nm or less, and more preferably 100 nm or less. At that time, a ball mill, a bead mill, or the like can be used for producing the fine powder.

  In this way, in the protective film forming step, a protective film made of an alkali metal fluoride layer is formed on the phosphor surface obtained in the acid cleaning step to form the phosphor of the present invention.

  Here, the raw material of the phosphor used in the phosphor manufacturing method as described above will be described. The phosphor material is preferably an inorganic phosphor material that constitutes the following compounds.

[Blue light emitting phosphor compound]
(BL-1): Sr ₂ P ₂ O ₇ : Sn ⁴⁺
(BL-2): Sr ₄ Al ₁₄ O ₂₅ : Eu ²⁺
(BL-3): BaMgAl ₁₀ O ₁₇ : Eu ²⁺
(BL-4): SrGa ₂ S ₄ : Ce ³⁺
(BL-5): CaGa ₂ S ₄ : Ce ³⁺
(BL-6): (Ba, Sr) (Mg, Mn) Al ₁₀ O ₁₇ : Eu ²⁺
(BL-7): (Sr, Ca, Ba, Mg) ₁₀ (PO ₄ ) 6Cl ₂ : Eu ²⁺
(BL-8): ZnS: Ag
(BL-9): CaWO ₄
(BL-10): Y ₂ SiO ₅ : Ce
(BL-11): ZnS: Ag, Ga, Cl
(BL-12): Ca ₂ B ₅ O ₉ Cl: Eu ²⁺
(BL-13): BaMgAl ₁₄ O ₂₃ : Eu ²⁺
(BL-14): BaMgAl ₁₀ O ₁₇ : Eu ²⁺ , Tb ³⁺ , Sm ²⁺
(BL-15): BaMgAl ₁₄ O ₂₃ : Sm ²⁺
(BL-16): Ba ₂ Mg ₂ Al ₁₂ O ₂₂ : Eu ²⁺
(BL-17): Ba ₂ Mg ₄ Al ₈ O ₁₈ : Eu ²⁺
(BL-18): Ba ₃ Mg ₅ Al ₁₈ O ₃₅ : Eu ²⁺
(BL-19): (Ba, Sr, Ca) (Mg, Zn, Mn) Al ₁₀ O ₁₇ : Eu ²⁺

[Green light-emitting phosphor compound]
(GL-1): (Ba, Mg) Al ₁₆ O ₂₇ : Eu ²⁺ , Mn ²⁺
(GL-2): Sr ₄ Al ₁₄ O ₂₅ : Eu ²⁺
(GL-3): (Sr, Ba) Al ₂ Si ₂ O ₈ : Eu ²⁺
(GL-4): (Ba, Mg) ₂ SiO ₄ : Eu ²⁺
(GL-5): Y ₂ SiO ₅ : Ce ³⁺ , Tb ³⁺
(GL-6): Sr ₂ P ₂ O ₇ —Sr ₂ B ₂ O ₅ : Eu ²⁺
(GL-7): (Ba, Ca, Mg) ₅ (PO ₄ ) ₃ Cl: Eu ²⁺
(GL-8): Sr ₂ Si ₃ O ₈ -2SrCl ₂ : Eu ²⁺
(GL-9): Zr ₂ SiO ₄ , MgAl ₁₁ O ₁₉ : Ce ³⁺ , Tb ³⁺
(GL-10): Ba ₂ SiO ₄ : Eu ²⁺
(GL-11): ZnS: Cu, Al
(GL-12): (Zn, Cd) S: Cu, Al
(GL-13): ZnS: Cu, Au, Al
(GL-14): Zn ₂ SiO ₄ : Mn ²⁺
(GL-15): ZnS: Ag, Cu
(GL-16) :( Zn, Cd) S: Cu
(GL-17): ZnS: Cu
(GL-18): Gd ₂ O ₂ S: Tb
(GL-19): La ₂ O ₂ S: Tb
(GL-20): Y ₂ SiO ₅ : Ce, Tb
(GL-21): Zn ₂ GeO ₄ : Mn
_{(GL-22): CeMgAl 11} O 19: Tb
(GL-23): SrGa ₂ S ₄ : Eu ²⁺
(GL-24): ZnS: Cu, Co
(GL-25): MgO.nB ₂ O ₃ : Ce, Tb
(GL-26): LaOBr: Tb, Tm
(GL-27): La ₂ O ₂ S: Tb
(GL-28): SrGa ₂ S ₄ : Eu ²⁺ , Tb ³⁺ , Sm ²⁺

[Red-emitting phosphor compound]
(RL-1): Y ₂ O ₂ S: Eu ³⁺
(RL-2): (Ba, Mg) ₂ SiO ₄ : Eu ³⁺
(RL-3): Ca ₂ Y ₈ (SiO ₄ ) ₆ O ₂ : Eu ³⁺
(RL-4): LiY ₉ (SiO ₄ ) ₆ O ₂ : Eu ³⁺
(RL-5): (Ba, Mg) Al ₁₆ O ₂₇ : Eu ³⁺
(RL-6): (Ba, Ca, Mg) ₅ (PO ₄ ) ₃ Cl: Eu ³⁺
(RL-7): YVO ₄ : Eu ³⁺
_{(RL-8): YVO 4} : Eu 3+, Bi 3+
(RL-9): CaS: Eu ³⁺
(RL-10): Y ₂ O ₃ : Eu ³⁺
(RL-11): 3.5MgO, 0.5MgF ₂ GeO ₂ : Mn
(RL-12): YAlO ₃ : Eu ³⁺
(RL-13): YBO ₃ : Eu ³⁺
(RL-14) :( Y, Gd) BO ₃ : Eu ³⁺

In particular, as a raw material of the inorganic phosphor, it is preferable to use a raw material constituting the (GL-14) Zn ₂ SiO ₄ : Mn ²⁺ .

Next, the phosphor according to the present invention will be described.
The phosphor of the present invention is a phosphor manufactured by the above-described manufacturing method, and a precursor forming step for forming a precursor of the phosphor, and a precursor obtained in the precursor forming step is fired to fluoresce In the phosphor manufacturing method comprising the firing step for forming the body, the phosphor obtained in the firing step is subjected to acid cleaning, and after the acid cleaning, a layer made of an alkali metal fluoride is formed on the phosphor surface. By forming the formed protective film, it is possible to prevent deterioration due to ion sputtering without disturbing the light emission of the phosphor.

  That is, in the phosphor of the present invention, by performing acid cleaning on the phosphor obtained in the firing step, impurities on the surface of the phosphor and defective portions generated in the manufacturing process before the acid cleaning step are dissolved and removed, The crystal plane that is the exposed phosphor surface becomes flat. In such a phosphor with a flat crystal plane, the atomic arrangement is also arranged, and thus the protective film formed thereafter grows a crystal on the crystal plane with the arranged atomic arrangement. As a result, the protective film can minimize the disorder of the crystal at the contact surface with the phosphor, and the crystallinity of the protective film can be increased so that the vacuum ultraviolet rays can be efficiently transmitted. It is comprised so that light emission may not be prevented.

  In addition, this protective film is intended to prevent deterioration due to ion sputtering, and is formed of a layer made of an alkali metal fluoride, so that the phosphor efficiently absorbs vacuum ultraviolet rays while preventing deterioration due to ion sputtering. It is configured so that it can receive light and does not interfere with light emission of the phosphor.

  In particular, when annealing is performed on the phosphor obtained in the acid cleaning step after the acid cleaning step prior to the formation of the protective film, the layer is formed with a smoother phosphor surface. By forming a protective film on the phosphor surface with a more crystallized surface and increasing the crystallinity of the protective film, it is possible to efficiently transmit vacuum ultraviolet rays, so that the phosphor does not interfere with light emission, It is configured to further prevent deterioration due to ion 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, and the partition walls 30 are connected to the display electrodes 11 in a plan view. 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 layers 35R, 35G, and 35B, the phosphor paste 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. The phosphor layers 35R, 35G, and 35B having the phosphor of the present invention attached thereto are formed on the partition wall side surface 30a and the bottom surface 30a by coating or filling the discharge cell 31 and then drying or firing. 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.

  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, in the acid cleaning step, impurities on the phosphor surface and defects generated in the precursor forming step and the firing step are dissolved and removed, and after the phosphor surface is flattened, A protective film is formed by forming a layer. As a result, a protective film is formed on the surface of the phosphor with a uniform crystal surface, and the crystallinity of the protective film is enhanced, so that vacuum ultraviolet rays can be efficiently transmitted, so that the phosphor does not interfere with light emission and ions Deterioration due to sputtering can be prevented.

  In this case, by performing an annealing step after the acid treatment step, it is possible to form a layer with a smoother phosphor surface, and to form a protective film on the phosphor surface with a more crystallized surface. Since the crystallinity can be increased and vacuum ultraviolet rays can be transmitted efficiently, the phosphor can not emit light and can be prevented from being deteriorated by ion sputtering.

Further, by performing the precursor forming step by a liquid phase method, the constituent elements of the obtained precursor particles can be made uniform at the atomic level, and the composition can be made uniform from the surface of the precursor to the inside. As a result, compared to the solid phase method, the amount of SiO ₂ added during firing can be reduced, and the disorder of the atomic arrangement on the phosphor surface can be minimized. Therefore, since the crystallinity of the protective film is further increased, vacuum ultraviolet rays can be transmitted efficiently, so that the phosphor can not emit light and deterioration due to ion sputtering can be further prevented.

In particular, when Zn ₂ SiO ₄ : Mn ²⁺ is used as the phosphor, the above-described effect appears remarkably because the deterioration width due to ion sputtering is large.

  Therefore, by using such a phosphor in a plasma display panel, the same effect as described above can be obtained, and the plasma display capable of improving the light emission luminance and preventing the deterioration due to ion sputtering. Can be a panel.

In evaluating the above-mentioned effects, the following items were examined.
In evaluating the emission luminance of the phosphor, the phosphor was irradiated with vacuum ultraviolet rays (excimer lamp), and then irradiated with vacuum ultraviolet rays, and the emission luminance of the phosphor at that time was measured.

  Also, when evaluating the deterioration of a phosphor due to ion sputtering, an ion sputtering apparatus is used to irradiate the phosphor with Ar ions, and the emission luminance of the phosphor before and after the Ar ion irradiation is measured. The degree to which the brightness is reduced (light emission luminance maintenance rate) was evaluated.

  Also, in evaluating the emission brightness of the plasma display panel and the deterioration of the emission brightness, when applying an equivalent sustain voltage to the electrodes of the plasma display panel, measure the emission brightness of the phosphor before and after applying a voltage for a long time, The light emission luminance immediately after lighting and the extent to which the light emission luminance is reduced by applying voltage for a long time (light emission luminance maintenance rate) were evaluated.

  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 brightness was evaluated. First, synthesis of phosphors 1 to 3 will be described.

1. Production of Phosphor (1) Production of Phosphor 1 1000 cc of pure water is used as solution A. 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 fired at 1260 ° C. for 3 hours in an atmosphere of 100% nitrogen to obtain a fired product. Thereafter, the obtained fired product was dispersed using a ball mill to obtain phosphor 1. 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 The phosphor 1 obtained by the production of (1) phosphor 1 was divided into two, and acid washing was performed on one of them to obtain phosphor 2. For acid cleaning, 5 g of phosphor 1 was added per 100 cc of hydrochloric acid 0.1 N, and after sufficient stirring, filtration and cleaning with pure water were performed.

(3) Fabrication of phosphor 3 The phosphor 2 obtained by the fabrication of (2) phosphor 2 is divided into two parts, one of which is fired at 500 ° C. for 3 hours in an air atmosphere, and then N ₂ 99% -H ₂ 1 A phosphor 3 was obtained by firing for 1 hr at 600 ° C. in a% atmosphere.

2. Formation of protective film First, MgF ₂ , CaF ₂ , and LiF manufactured by High Purity Chemical Laboratory Co., Ltd. were dispersed using a bead mill disperser (DISPERMATT SL-C5 manufactured by VMA-GETZMANN) to form fine particles having an average particle diameter of 50 nm. It produced about each. The particle size was measured using Zeta Sizer 1000 (Malvern). Using these fine particles, a phosphor film is provided on the surface of phosphors 1 to 3 obtained by the above-described method, and phosphor samples 1 to 1 are used as samples for the examples and comparative examples. Sample 5 is prepared.

(1) Preparation of phosphor sample 1 Phosphor 2 was dispersed in 50 cc of ethanol per 10 g, and 1.6 g of MgF ₂ fine particles obtained by the above-described method were added thereto, and mixed well in a mortar. Then, it is filtered and dried. Thereafter, phosphor sample 1 was obtained by firing at 1000 ° C. for 3 hours in an atmosphere of 100% nitrogen to form a protective film on the phosphor surface.

(2) Preparation of phosphor sample 2 A phosphor sample was prepared in the same manner as in (1) except that the phosphor 2 used in the preparation of the phosphor sample 1 of (1) was changed to the phosphor 3. This was designated as phosphor sample 2.

(3) Preparation of phosphor sample 3 The phosphor sample was prepared in the same manner as in (1) except that the MgF ₂ fine particles used in the preparation of phosphor sample 2 in (2) were changed to CaF ₂ fine particles. The phosphor sample 3 was prepared.

(4) Preparation of phosphor sample 4 A phosphor sample was prepared in the same manner as in (1) except that the MgF ₂ particles used in the preparation of phosphor sample 2 in (2) were changed to LiF particles. This was used as phosphor sample 4.

(5) Production of phosphor sample 5 of comparative example Phosphor sample in the same manner as in (1) except that phosphor 2 used in the production of phosphor sample 1 of (1) is changed to phosphor 1. This was made into a phosphor sample 5.

3. Measurement of Luminous Luminance Luminescent luminance was measured for the phosphor samples 1 to 5 obtained above.
The measurement of light emission luminance 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 luminance of the obtained green light was measured using a detector (MCPD-3000 (manufactured by Otsuka Electronics Co., Ltd.)). The peak luminance of light emission of the phosphor samples 1 to 4 was obtained as a relative value with the phosphor sample 5 of the comparative example as 100, and is shown in Table 1 below.

  Further, with respect to the phosphor sample 1 to phosphor sample 5 obtained above, the emission luminance of the phosphor sample before and after ion sputtering was measured, and the emission luminance maintenance ratio was calculated by the following formula (1). Is shown in Table 1 below.

  Emission luminance maintenance ratio = [(Emission luminance after ion sputtering) / (Emission luminance before ion sputtering)] × 100 (1)

  When performing sputtering, an ion sputtering apparatus SC-701 manufactured by Sanyu Electronics Co., Ltd. was used, and sputtering was performed for 5 minutes in an Ar gas atmosphere under a discharge voltage of 1.0 kV, a discharge current of 5 mA, and a vacuum of 13 Pa.

  As described above, it can be seen that the phosphor luminance retention rate is increased in phosphor samples 1 to 4 subjected to the acid treatment. In addition, it can be seen that phosphor samples 2 to 4 subjected to the annealing treatment in addition to the acid treatment are further improved in the emission luminance and increased in the emission luminance maintenance ratio.

[Example 2]
In Example 2, a plasma display panel was manufactured using the phosphor sample 2 and the phosphor sample 5 obtained in Example 1, and the light emission luminance 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 sample 2 produced in Example 1 was used and mixed with the following composition to prepare the phosphor paste 1 Went.
Phosphor sample 2 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 the phosphor paste of the comparative example Except for changing the phosphor sample 2 of the phosphor paste 1 to the phosphor sample 5, the phosphor paste 2 was adjusted in the same manner to obtain a phosphor paste of the comparative example. .

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., thereby forming 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 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. Next, regarding the plasma display panel 1 and the plasma display panel 2, the light emission brightness immediately after the plasma display panel was turned on was measured. The results are shown in Table 2 below. The measurement of the light emission luminance is to measure the white luminance when an equivalent sustain voltage (170 V AC voltage) is applied to the electrodes, and the plasma display panel 2 has a light emission luminance of 100. Relative emission luminance was determined.
In addition, the emission luminance at 1000 hours after lighting was measured to obtain the emission luminance maintenance ratio.

As described above, the plasma display panel 1 manufactured using the phosphor sample in which the MgF ₂ film is formed on the phosphor surface after the acid treatment and the annealing treatment has high emission luminance and excellent emission luminance maintenance rate. I understand that.

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 (6)

  A precursor forming step for forming a precursor of the phosphor, a firing step for firing the precursor obtained in the precursor forming step to form a phosphor, and the phosphor obtained in the firing step. A phosphor manufacturing method comprising: an acid cleaning step for acid cleaning; and a protective film forming step for forming a protective film made of an alkali metal fluoride on the surface of the phosphor obtained in the acid cleaning step. .   2. The method according to claim 1, further comprising an annealing step of performing an annealing process on the phosphor obtained in the acid cleaning step after the acid cleaning step, and performing the protective film forming step after the annealing step. A method for manufacturing the phosphor.   The method for producing a phosphor according to claim 1 or 2, wherein the precursor forming step is a liquid phase method. The phosphor Zn ₂ Si0 _4: The method for producing a phosphor as claimed in any one of claims 3, characterized in that it consists of crystal structure in the Mn ^2+.   The fluorescent substance manufactured with the manufacturing method as described in any one of Claims 1-4.   A plasma display panel comprising the phosphor according to claim 5 in a discharge cell.

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