JP4683949B2 - Phosphor, method for manufacturing the same, and plasma display panel using the phosphor - Google Patents

Description

  The present invention relates to a phosphor, a manufacturing method thereof, and an improvement of a plasma display panel using the phosphor.

  Conventionally, phosphors have been used in various applications such as lighting fixtures such as fluorescent lamps, television and personal computer displays. In order to manufacture such a phosphor, as shown in Non-Patent Document 1 below, a method of firing a raw material at a high temperature has been generally adopted.

Patent Document 1 below discloses a method for producing a silicate phosphor having high emission intensity and short afterglow time.
JP 2004-51919 A Fluorescent material handbook Fluorescent materials association society OH Ohmsha (1987) 218-221 pages

  However, the above-described conventional technique has a problem that the firing temperature of the raw material needs to be higher than 1100 ° C., and an expensive firing furnace is required.

  Moreover, since the particle size of the obtained phosphor is small (the above-mentioned Patent Document 1 describes that 1 μm or less is preferable) and the hygroscopic property is high, the interelectrode insulation for causing plasma discharge is deteriorated, and the discharge There was a problem that it became difficult to occur. Furthermore, since it is a fine particle, when it was applied alone, there was a problem that it peeled off immediately.

  As a means to solve these problems, a method of mixing and applying a phosphor with a highly insulating paint is also employed, but the problem of reduced luminous efficiency due to the inclusion of a paint that is not a phosphor substance. was there.

  The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to use a phosphor that has low hygroscopicity and can be manufactured in an inexpensive electric furnace, a manufacturing method thereof, and the phosphor. It is to provide a plasma display panel.

In order to achieve the above object, the present invention provides a method for producing a phosphor containing silicon as a base material, wherein the phosphor raw material is mixed with a molten salt containing NaF, Na ₂ SiF ₆ and SiO _2. Features.

  Here, the molten salt preferably contains NaCl and / or KCl, and Si is preferably added.

  In the phosphor manufacturing method, it is preferable that the mixture of the phosphor raw material and the molten salt raw material is fired or heated at 700 ° C. or higher, particularly 700 to 900 ° C. Is preferred.

  Moreover, in the said manufacturing method of a fluorescent substance, it is suitable for the said baking or heating time to be less than 3 hours.

In the manufacturing method of the phosphor, it is preferred that comprises ZnO and MnCO ₃ in the phosphor raw material.

  Moreover, in the said manufacturing method of a fluorescent substance, it is suitable that the molar ratio of the silicon contained in the said mixture is 1-3 times of zinc.

  Moreover, in the said manufacturing method of a fluorescent substance, it is suitable that the molar ratio of the said molten salt is 0.05-1 times of the said ZnO, and it is suitable that it is especially 0.5-0.7 times. is there.

Further, the present invention is a phosphor manufactured by the method for manufacturing each phosphor described above, wherein the composition formula of the phosphor is Zn ₂ SiO ₄ : Mn or CaSiO ₃ : Pb, Mn or BaSi ₂ O ₅ : Pb or Y ₂ SiO ₅ : Ce, Tb

  Here, the crystal structure of the phosphor is preferably needle-like. The phosphor crystal preferably has a diameter of 0.5 to 5 μm and a length of 5 to 50 μm.

  The present invention is also a plasma display panel, characterized in that a phosphor layer containing the phosphor is provided.

  Hereinafter, the best mode for carrying out the present invention (hereinafter referred to as an embodiment) will be described with reference to the drawings.

FIG. 1 is a flowchart showing a procedure of a method for manufacturing a phosphor according to the present invention. The phosphor of the present invention has a structure in which a metal ion as an activator is added to a base material containing silicon. In FIG. 1, a predetermined amount of the phosphor material is weighed (S1). When the phosphor to be manufactured is, for example, Zn ₂ SiO ₄ : Mn, the raw materials of the phosphor are ZnO and MnCO ₃ .

Next, a predetermined amount of molten salt raw material containing NaF, Na ₂ SiF ₆ and SiO ₂ is weighed and mixed with the phosphor raw material in an automatic mortar for 1 hour (S2). Here, the automatic mortar is an apparatus that stirs and mixes the materials in the mortar with a magnetic stirrer. This molten salt is composed of, for example, NaCl, KCl, NaF, Na ₂ SiF ₆ and SiO _2, and it is preferable that Si is further added.

  Next, the raw material of the phosphor and the raw material of the molten salt are mixed (S3), and a predetermined amount of this mixture is put in a crucible and baked at 700 to 900 ° C. for 30 minutes to 3 hours. However, when the firing temperature is set to 900 ° C. or higher, the firing time can be shortened to less than 30 minutes, for example, about 5 minutes (S4).

  The molten salt remaining in the crucible after firing is dissolved with pure water (S5), and the solution is centrifuged to obtain the phosphor according to the present invention from the precipitate (S6).

Here, since the molten salt contains NaF and Na ₂ SiF ₆ , SiF ₆ ⁴⁻ ions are generated during firing, and the base material and silicon are easily bonded to each other. By being oxidized, a base crystal grows. At the same time, the metal ion as the activator is incorporated into the crystal structure, thereby having a function as a phosphor.

In addition, according to the manufacturing method of the present invention, various phosphors containing silicon as a base material in addition to Zn ₂ SiO ₄ : Mn, such as CaSiO ₃ : Pb, Mn, BaSi ₂ O ₅ : Pb, Y ₂ SiO ₅ : Ce, Tb, etc. can be produced.

  Many of the phosphors manufactured by the above process are composed of needle crystals. This acicular crystal has low hygroscopicity as compared with conventional spherical phosphors, and can suppress interelectrode insulation deterioration for plasma discharge.

  The phosphor described above can be used for a phosphor layer of a plasma display, for example. As described above, since the phosphor according to this embodiment has low hygroscopicity and can maintain insulation, the display quality of the plasma display can be maintained high for a long period of time.

  The embodiment of the present invention will be described below. The following examples are examples of the present invention, and the present invention is not limited to these examples.

Example 1.
As a raw material of the phosphor, ZnO and MnCO _3, the molar ratio of ZnO and MnCO ₃ (ZnO: MnCO ₃₎ is 15: 1 and were weighed so as to, as a raw material of the molten salt, NaCl ZnO is against 1mol Is 1 mol, KCl is 1 mol, NaF is 0.6 mol, Na ₂ SiF ₆ is 0.13 mol, and SiO ₂ is further weighed to 2 mol, and the phosphor raw material, molten salt raw material and SiO ₂ are automatically added for 1 hour. Mix in mortar.

  Next, 400 mg of the above mixture is placed in a crucible and baked at a temperature of 700, 800, and 900 ° C. for 30 minutes, 1, 2, 3, and 6 hours, for a total of 15 ways, and the molten salt remaining in the crucible Was dissolved in pure water, and the solution was centrifuged to obtain a phosphor sample from the precipitate. A muffle type electric furnace (FT-100 manufactured by FULL-TECH) was used for firing the raw material.

  The phosphor samples obtained as described above were able to confirm fluorescence due to ultraviolet irradiation under any conditions, although there was a difference in the phosphor concentration.

Further, in the mixture of raw materials, only the molar ratio of SiO ₂ to ZnO was changed to 100, 200, and 300%, and calcined at 900 ° C. for 1 hour, and the molten salt remaining in the crucible was purified with pure water. A phosphor sample was obtained from the precipitate by dissolving and centrifuging the solution.

  Regarding the phosphor samples obtained as described above, the fluorescence due to ultraviolet irradiation could be confirmed under any conditions, although there was a difference in the phosphor concentration.

Example 2
Based on the results of Example 1 above, in order to further narrow down the optimum mixing ratio, the molar ratio of ZnO and MnCO ₃ is 15: 1, and the molar ratio of SiO ₂ is 200% or 300% of ZnO. , The molar ratio of NaCl of the molten salt (molar ratio NaCl: KCl: NaF: Na ₂ SiF ₆ = 1: 1: 0.6: 0.13) to ZnO is 5, 10, 25, 40, 50, Weigh to 60, 70, 100, 200, 500%, mix in an automatic mortar for 1 hour, fire at 900 ° C. for 1 hour, dissolve the molten salt remaining in the crucible with pure water, A phosphor sample was obtained from the precipitate by centrifuging the lysate. Incidentally, hereinafter, the molar ratio of molten salt to ZnO refers to NaCl to ZnO contained in the molten salt having the above composition (NaCl: KCl: NaF: Na ₂ SiF ₆ = 1: 1: 0.6: 0.13). Refers to the molar ratio.

  Among the phosphor samples obtained as described above, fluorescence due to ultraviolet irradiation could be confirmed for those having a molar ratio of molten salt to ZnO of 5 to 100%.

  In particular, when the molar ratio of the molten salt to ZnO was 50 to 70%, the phosphor could be generated most efficiently.

FIG. 2 shows a phosphor synthesized with a mole ratio of molten salt to ZnO of 60%, a mole ratio of SiO ₂ to ZnO of 200%, a firing temperature of 900 ° C., and a firing time of 1 hour. The state observed with a microscope (5000 times) is shown. As shown in FIG. 2, almost all of the phosphor is composed of needle crystals. Further, it can be seen from the magnification of the microscope that the acicular crystals have a diameter of 1 to 2 μm and a length of 5 to 30 μm. It was also observed that the needle-like crystals were transparent.

Example 3
As a raw material of the phosphor, ZnO and MnCO _3, the molar ratio of ZnO and MnCO ₃ (ZnO: MnCO ₃₎ is 15: 1 and were weighed so as to, as a raw material of the molten salt, NaCl ZnO is against 1mol 1 mol, KCl 1 mol, NaF 0.6 mol, Na ₂ SiF ₆ 0.13 mol, SiO _{2 2} mol, Si 2 mol, and phosphor raw material, molten salt raw material, SiO ₂ And Si were mixed in an automatic mortar for 1 hour. This was baked at 800 ° C. for 30 minutes, the molten salt remaining in the crucible was dissolved in pure water, and the dissolved solution was centrifuged to obtain a phosphor sample from the precipitate.

  When the obtained phosphor sample was irradiated with ultraviolet rays and observed for fluorescence, high-intensity green fluorescence was observed.

From the above, it can be seen that high brightness Zn ₂ SiO ₄ : Mn phosphor can be synthesized at a lower firing temperature by adding Si to the molten salt.

Comparative Example As a comparative example of the above-described example, a phosphor was synthesized by a powder mixed sintering method, which has been conventionally performed. However, in order to make the conditions the same as when using the molten salt, the sintering was performed only once.

As phosphor materials, ZnO, MnCO ₃ and SiO ₂ were weighed to a molar ratio of 13: 1: 26, and these were mixed in an automatic mortar for 1 hour.

  Next, the phosphor raw material was taken in a crucible, and the firing temperature was set to four types of 700 ° C., 800 ° C., 900 ° C., and 1100 ° C. and fired to obtain a phosphor sample. The firing time was also set to three types of 1 hour, 3 hours, and 6 hours.

  The phosphor sample obtained as described above was observed for fluorescence by ultraviolet irradiation. As a result, no fluorescence was observed at 900 ° C. or lower, and no fluorescence was observed at 1100 ° C. for 1 hour.

  Thus, it can be seen that in this comparative example, it is necessary to perform firing at a higher temperature for a longer time than in the above-described examples (900 ° C. or less, firing within 1 hour). For this reason, in order to implement this comparative example, an expensive firing furnace capable of firing at a high temperature is required.

It is a flowchart which shows the procedure of the manufacturing method of the fluorescent substance concerning this invention. It is a figure which shows a mode that the fluorescent substance manufactured with the manufacturing method of the fluorescent substance concerning this invention was observed with the microscope.

Claims (16)

A method for producing a phosphor containing silicon as a base material, wherein the phosphor raw material is mixed with a molten salt containing NaF, Na ₂ SiF ₆ , and SiO ₂ . 2. The method for manufacturing a phosphor according to claim 1, wherein the molten salt contains NaCl. 3. The method for manufacturing a phosphor according to claim 1, wherein the molten salt contains KCl. 4. The method for manufacturing a phosphor according to claim 1, wherein Si is added to the molten salt. 5. 5. The method for producing a phosphor according to claim 1, wherein a mixture of the phosphor raw material and the molten salt raw material is fired or heated at 700 ° C. or higher. A method for manufacturing a phosphor. 6. The method for producing a phosphor according to claim 5, wherein the mixture is fired or heated at 700 to 900 [deg.] C. The method for producing a phosphor according to claim 5 or 6, wherein the firing or heating time is within 3 hours. The method for manufacturing a phosphor according to any one of claims 5 to 7, wherein the phosphor material contains ZnO and MnCO ₃ . 9. The method for manufacturing a phosphor according to claim 8 , wherein a molar ratio of silicon contained in the mixture is 1 to 3 times that of zinc. Claims 1 A phosphor phosphor produced by the method of any one of claims 9, composition formula of the phosphor is Zn 2 _SiO 4: phosphor, characterized in that the _Mn . A phosphor manufactured by the method for manufacturing a phosphor according to any one of claims 1 to 9 , wherein the phosphor has a composition formula of CaSiO ₃ : Pb, Mn. . A phosphor manufactured by the method for manufacturing a phosphor according to any one of claims 1 to 9 , wherein the phosphor has a composition formula of BaSi ₂ O ₅ : Pb. . A phosphor manufactured by the method for manufacturing a phosphor according to any one of claims 1 to 9 , wherein the composition formula of the phosphor is Y ₂ SiO ₅ : Ce, Tb. Phosphor. The phosphor according to any one of claims 10 to 13 , wherein the phosphor has a needle-like crystal structure. The phosphor according to any one of claims 10 to 14 , wherein the phosphor crystal has a diameter of 0.5 to 5 µm and a length of 5 to 50 µm. A plasma display panel comprising a phosphor layer containing the phosphor according to any one of claims 10 to 15 .