JP2008260643A - Glass powder, glass paste, and method of manufacturing glass powder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of favorably manufacturing a glass powder, used for forming a dielectric layer or a partition suppressing yellowing and excellent in transmittance and dielectric strength of a plasma display panel. <P>SOLUTION: The method of manufacturing the glass powder involves a dry pulverizing process. The dry pulverizing process includes a water-supplying pulverizing process (1) of pulverizing in a casing 31 under the condition of flowing a gas while continuing water supply into the casing 31 of the pulverizer 30 containing a vitric material of an object to be pulverized until a final supplied total water amount comes to the amount corresponding to at least 10 mass% of a total vitric material amount contained, and a non-water-supplying pulverizing process (2) of further continuing the same pulverization in the casing 31 under the condition of flowing the gas while stopping water supply after the supplied total water amount comes to a predetermined amount. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a glass powder manufacturing technique. In detail, it is related with the manufacturing method of the glass powder accompanying a dry-type grinding | pulverization process, the glass powder manufactured by this manufacturing method, and its utilization. In particular, the present invention relates to glass powder and glass paste for forming a dielectric layer or a partition wall of a plasma display panel.

Compared with a conventional cathode ray tube, the plasma display panel can obtain a clear image and can be thinned even on a large screen. For this reason, it is spreading to televisions and computer monitors.
As schematically shown in FIG. 1, the plasma display panel 1 includes a front glass plate 2 and a back glass plate 3. A display electrode (hereinafter also referred to as “Ag electrode”) 5 made of silver (Ag) as an electrode material is formed on the surface of the front glass plate 2 facing the back glass plate 3, and the Ag electrode 5 is further formed. A transparent dielectric layer 6 is formed for protecting the battery and maintaining discharge. A protective layer 7 is further formed on the surface of the transparent dielectric layer 6. On the other hand, on the side of the rear glass plate 3 facing the front glass plate 2, an address electrode 9, a partition wall 4, and a phosphor layer 10 covered with a white dielectric layer 8 are formed. The partition walls 4 divide the glass plates 2 and 3 at predetermined positions to form a large number of cells, that is, discharge spaces.

By the way, the transparent dielectric layer 6 formed on the front glass plate 2 is required to have high transparency and high transparency. Further, the white dielectric layer 8 formed on the rear glass plate 3 is required to have high voltage resistance, and the partition wall 4 is required to have a fine cell structure. The dielectric layers 6 and 8 and the barrier ribs 4 are formed by applying a paste material mainly composed of glass powder on the Ag electrodes 5 and 9 and the white dielectric layer 8 and firing at an appropriate temperature. .
Conventionally, the glass powder (that is, the main component of the glass paste) forming such a dielectric layer or partition has been produced by wet grinding using a vitreous material as a starting material. However, there are demands such as low cost, shortening of lead time, and miniaturization of plasma display panels (that is, further refinement of glass powder), and in recent years, glass powder for such use is manufactured by dry pulverization in order to realize these. It is being considered. For example, the following patent documents describe a method of producing glass powder for forming a dielectric layer of a plasma display panel by dry pulverization.

JP 2002-160939 A JP 2002-279904 A JP 2006-240970 A

Conventionally, yellowing of a dielectric layer or a partition (particularly, a transparent dielectric layer) is one of the problems that a dielectric layer or partition formed on an Ag electrode of a plasma display panel has. Such yellowing is caused by the diffusion of Ag ions generated from the Ag electrode into the dielectric layer or partition during firing of the glass powder constituting the dielectric layer or partition (that is, the paste coating product), and further the dielectric layer or partition. It is thought that it is generated by reducing Ag in the formation of Ag colloid. Such yellowing is more likely to occur when glass powder produced by a dry pulverization method is used than glass powder produced by a wet pulverization method. In each of the above-mentioned patent documents, the occurrence of yellowing is a problem and measures for avoiding the occurrence are discussed, but the effect is not sufficient.
Further, in dry pulverization, gas molecules such as CO ₂ and H ₂ O are applied to the pulverized surface of the glass composition that has been pulverized and newly formed and activated (for example, the pulverized surface activated by breaking the Si—O bond). Is easily adsorbed. However, excessive adsorption of such gas molecules is not preferable because it causes bubbles to remain in the dielectric layer or partition after firing, which leads to a decrease in transmittance and withstand voltage.

  Therefore, the present invention was created to solve the above-mentioned conventional problems related to glass powder used for forming a dielectric layer or a partition wall (for example, a transparent dielectric layer) of a plasma display panel. An object of the present invention is to provide a glass powder and a glass paste material that can suppress and form a dielectric layer or partition wall having excellent transmittance and voltage resistance. Another object is to provide a method for suitably producing such glass powder.

The glass powder manufacturing method provided by the present invention is a glass powder manufacturing method involving a dry pulverization step.
In the glass powder manufacturing method provided by the present invention, the dry pulverization step (1) contains the final total amount of added water in the casing of the pulverizer in which the vitreous material to be pulverized is accommodated. A water addition pulverization step of performing a pulverization process in the casing in an aerated state while continuing to supply water until the amount corresponds to at least 10% by mass of the total amount of the vitreous material,
(2) a moisture non-addition crushing step of stopping the water supply after the total amount of added water reaches a predetermined value and continuing the same crushing process in the aerated casing;
It is characterized by including.
In the present specification, the “pulverization process in the aerated casing” refers to a pulverization process in a state where the vitreous material in the casing can be gradually dried by ventilation in a state where moisture is not supplied. For example, by using various dry pulverizers (such as a media stirring mill) in which a gas flow is introduced into a casing (a container for pulverization) together with the pulverized material, the “pulverization process in the aerated casing” can be performed. It can be carried out.

In the glass powder manufacturing method having such a structure, the vitreous material is pulverized based on dry pulverization. The dry pulverization step is the above (1) moisture addition pulverization step (moisture addition pulverization treatment) and the above step (2) moisture. And a non-addition pulverization step (moisture non-addition pulverization treatment).
By performing dry pulverization in two successive steps, a glass powder in which gas molecules such as CO ₂ and H ₂ O are less likely to be adsorbed than the glass powder obtained by conventional dry pulverization can be produced. Therefore, according to the present manufacturing method, for example, a glass powder for forming a dielectric layer or a partition wall (for example, a transparent dielectric layer) of a plasma display panel, which is a glass powder having the same composition obtained by conventional dry pulverization Thus, it is possible to provide a glass powder that can form a dielectric layer or a partition wall (for example, a transparent dielectric layer) that hardly causes yellowing or is excellent in permeability and voltage resistance. Moreover, the glass paste which has the obtained glass powder as a main component can be provided.

Accordingly, the present invention provides a glass powder for forming a dielectric layer or barrier rib of a plasma display panel as another aspect for solving the above-mentioned problems, wherein the dielectric layer or barrier rib (for example, a transparent dielectric layer) is formed. Provided is a glass powder produced by any of the production methods disclosed herein starting from a vitreous material prepared to the resulting oxide composition.
Further, as another aspect, a glass paste for forming a dielectric layer or partition of a plasma display panel, which is prepared to an oxide composition capable of forming a dielectric layer or a partition (for example, a transparent dielectric layer). Provided is a glass paste mainly composed of glass powder produced by any one of the production methods disclosed herein using a vitreous material as a starting material.
As another aspect, a dielectric layer formed by using a glass powder produced by any of the production methods disclosed herein (typically as the glass paste) and / or A plasma display panel including a partition wall (for example, a transparent dielectric layer) is provided.

In the glass powder manufacturing method of the present invention in one preferred embodiment, the total amount of added water is set to an amount corresponding to 20 to 60% by mass of the total amount of the vitreous material. Preferably, the moisture supply has a moisture content of 0.5 to 30% by mass of the vitreous material (crushed material) in the casing at the time when the moisture supply is stopped (that is, at the end of the moisture addition and pulverization step). It is performed so that it is kept in the range. The moisture content (% by mass) in the present specification is the amount of moisture that can be released by heating a crushed glass (powder). Specifically, a fixed amount of glass powder (for example, 2 g) is dried in a ventilation dryer at 80 ° C. until no weight reduction is observed, and the moisture content (mass%) obtained from the weight change before and after the drying treatment is determined. It becomes an indicator.
Glass powder that can form a dielectric layer or a partition wall (for example, a transparent dielectric layer) that has better permeability and voltage resistance than glass powder of the same composition obtained by conventional dry pulverization or wet pulverization by such condition setting. Can be manufactured.

Preferably, in the (2) non-moisture addition pulverization step, the water content of the crushed glass (glass powder) in the casing is in the range of 0.1 to 0.8% by mass (particularly 0.1 to 0.00). 6 mass%, more preferably 0.4 to 0.6 mass%).
Manufacturing a glass powder capable of forming a dielectric layer or a partition wall (for example, a transparent dielectric layer) that is particularly excellent in permeability and voltage resistance by performing a (2) non-moisture pulverization step under such conditions. Can do.
Or you may provide a drying process process separately so that the moisture content rate of a glass powder may become in the said range after a (2) moisture non-addition crushing process. For example, (2) the moisture-free pulverization treatment is performed until the moisture content of the crushed glass (glass powder) in the casing is in the range of 1 to 2% by mass, and then the drying treatment step (for example, in a suitable dryer) ) Even if the moisture content of the glass powder is in the range of 0.1 to 0.8 mass% (particularly 0.1 to 0.6 mass%, more preferably 0.4 to 0.6 mass%). Good.

  Hereinafter, preferred embodiments of the present invention will be described. The matters necessary for the implementation of the present invention are matters other than matters particularly mentioned in the present specification (for example, contents of (1) moisture-added pulverization treatment and (2) non-moisture-added pulverization treatment, etc.) Therefore, it can be grasped as a design matter of a person skilled in the art based on the prior art in the field. The present invention can be carried out based on the contents disclosed in this specification and common technical knowledge in the field.

  As described above, the glass powder production method of the present invention is a method characterized by performing dry pulverization including two steps of (1) a water addition pulverization step and (2) a water non-addition pulverization step. There is no restriction | limiting in particular in the content of a process. For example, depending on the purpose, various compound raw materials (typically oxide raw materials such as silica) are procured, they are prepared so as to have a desired composition ratio, and such prepared materials are placed in a heating furnace such as an electric furnace. And dissolved under suitable high temperature conditions. Next, the melt taken out from the furnace is rapidly cooled to obtain a vitreous material (starting material) having a predetermined shape (for example, flake shape) to be crushed.

Next, the vitreous material having the desired composition prepared as described above is supplied (accommodated) to a casing of an appropriate pulverizer for dry pulverization, and the dry pulverization step according to the present invention is performed.
Although it does not specifically limit, the dry pulverization which concerns on this invention can be implemented suitably by employ | adopting the dry pulverizer (media stirring mill) 30 typically shown in FIG.
A media (medium) stirring mill 30 shown in the figure includes a casing 31 provided with an agitator 32 at the bottom and a classifier (typically a rotor classifier) 34 at the top. The casing 31 is formed with an air supply pipe 33 for introducing a gas flow into the casing 31 from the bottom of the casing 31. The rotor 34 is connected to an exhaust pipe 35 for sending the classified powder to the outside of the casing together with the gas flow. The exhaust pipe 35 is connected to a cyclone (dust separator) 36 and a bag filter (dust collector) 37 outside the casing. Although not shown in the figure, by installing an air compressor and / or a blower in the upstream area of the air supply pipe 33 and / or the downstream area of the exhaust pipe 35 (bag filter 37), gas (typically Air) can be introduced to generate a gas flow.

With such a series of apparatuses, glass powder having a predetermined particle size range can be obtained by dry pulverization. Furthermore, a glass powder having a relatively narrow particle size distribution (that is, having a uniform particle size) can be obtained by providing an appropriate classifier 34 in the casing 31.
Then, by installing an injector (injector) 38 for supplying moisture to a part of the air supply pipe 33 (or by attaching a vaporizer and utilizing evaporation of moisture by gas flow), a desired amount can be obtained. The water can be supplied into the casing 31 together with the gas flow, preferably in the form of a mist or steam. Alternatively, a device capable of supplying moisture to a part of the wall surface of the casing 31 (may be an injector nozzle or a simple liquid supply port) may be separately provided.
In addition, since the apparatus structure mentioned above can utilize the existing grinder etc., the further detailed description of the apparatus structure itself is abbreviate | omitted.

With the above apparatus configuration, the dry pulverization according to the present invention can be suitably performed. That is, an appropriate medium (a bead such as a steel ball or ceramic ball) 40 is put in the casing 31 in advance, and a vitreous material as a starting material to be crushed is supplied into the casing 31. Then, the agitator 32 is operated to start the dry pulverization process. In the dry pulverization method according to the present invention, first, the (1) moisture addition pulverization process is started. That is, moisture is continuously supplied into the casing 31 together with an appropriate amount of gas flow for a predetermined time.
Although not particularly limited, the water supply is continued until the final total amount of added water reaches an amount corresponding to at least 10% by mass of the total amount of the vitreous material accommodated in the casing 31. At this time, there is no particular limitation because it depends on the degree and scale of the pulverization process or the content of the pulverizer. For example, the final total amount of added water is 10 to 100% by mass, particularly 10 to 70% of the total amount of the vitreous material. It is preferable to set to an amount corresponding to mass%, and further 20 to 60 mass%. More preferably, it is set to an amount corresponding to about 40 to 60% by mass. If the final added water total amount is too small, the effect required by the present invention cannot be obtained. On the other hand, if the final added water total amount is excessive, it is necessary to perform a long-time non-water-added pulverization treatment. In addition, there is a possibility that a glass powder that is finally insufficiently dried may be obtained. Insufficient drying is not preferable because the amount of water remaining in the glass powder becomes excessive, which may become water vapor gas during firing and remain in the dielectric layer. This is because the remaining steam gas (that is, generation of bubbles) causes a decrease in transmittance and voltage resistance, or yellowing.

It is preferable to continuously supply such an amount of moisture into the casing over, for example, 10 minutes to 120 minutes (preferably 20 to 60 minutes, for example, 30 to 40 minutes). In addition, although it is moisture supply into the casing 31, it is not preferable to supply a large amount (for example, the total amount or a half of the amount) of moisture into the casing 31 at one time. It is preferable to continuously supply a small amount of moisture so that the moisture content of the glassy material does not fluctuate so much and is stable.
For example, the moisture content of the vitreous material in the casing 31 at the end of the moisture addition pulverization process, that is, when the moisture supply is stopped is in the range of about 0.2 to 30% by mass, preferably 0.5 to 30% by mass. It is particularly preferable to adjust the moisture supply amount (moisture supply rate) and the gas flow rate (flow velocity) to the casing 31 associated therewith so as to be maintained in the range. By setting such conditions, for example, a glass powder for forming a dielectric layer or partition wall (for example, a transparent dielectric layer) of a plasma display panel, which has better transmittance and withstand voltage than conventional ones and yellowing occurs. It is possible to produce a glass powder that can form a difficult dielectric layer or barrier rib (for example, a transparent dielectric layer).

Thus, after the water addition pulverization step, the pulverization process is continued in a state where the water supply is stopped (moisture non-addition pulverization step).
Such a non-moisture-added pulverization process may be performed by the same pulverization process as the above-described moisture-added pulverization process, except that no water is supplied. The duration of the water-free pulverization treatment is not particularly limited, but the water content of the crushed glass (glass powder) in the casing 31 is 0.1 to 0.8% by mass (particularly 0.1 to 0.6). It is preferable to continue until it is in the range of mass%, more preferably 0.4 to 0.6 mass%. Although it may vary depending on the temperature and the flow rate of the gas flow, for example, a pulverization treatment of about 10 to 120 minutes is preferable.

Or you may provide a drying process process separately so that the moisture content rate of a glass powder may become in the said range after a (2) moisture non-addition crushing process. For example, (2) non-moisture-added pulverization is performed until the water content of the crushed glass (glass powder) in the casing 31 is in the range of 1 to 2% by mass or more, and then the drying process is performed. You may carry out until it becomes the range whose content rate is 0.1-0.8 mass% (especially 0.1-0.6 mass%, More preferably, 0.4-0.6 mass%).
For example, in the dry pulverizer 30 as shown in FIG. 2, the gas flow rate and the temperature during the pulverization process (usually room temperature to 100 ° C., typically about 20 to 40 ° C.) are also affected. There is a case where the glass powder having a relatively high moisture content is wound up above the casing by the introduced gas flow, sent to the cyclone 36 or the bag filter 37 through the rotor 34, and recovered. In this case, after recovering the glass powder, the above-mentioned preferable range is obtained in an appropriate dryer (for example, a dryer (oven) provided with heating means such as a heater, a ventilation dryer is preferable) or in the atmosphere. It is preferable to perform a drying process until it becomes a moisture content.

  In the pulverization method according to the present invention, the particle size of the glass powder to be produced is not particularly limited. A glass powder having a particle size to be obtained can be obtained. For example, as a glass powder for use in forming a transparent dielectric layer of a plasma display panel, a glass powder having an average particle diameter of preferably about 0.1 to 5 μm (more preferably 0.1 to 2 μm) may be produced. . In the present specification, the “average particle diameter” refers to D50 (median diameter) in the particle size distribution of the powder. Such D50 can be easily measured by a particle size distribution measuring apparatus based on a conventionally known laser diffraction method, light scattering method, or the like.

In the glass powder production method of the present invention, the composition of the glass powder to be produced is not particularly limited as long as dry pulverization can be performed while supplying moisture.
A typical example of a glass powder that can be suitably produced by applying the method of the present invention is a glass powder made of a glass composition for forming the transparent dielectric layer 6 of the plasma display panel 1 as shown in FIG. . Conventionally known glass powders of various compositions used for this purpose can be produced.
An example is a lead-free oxide glass composition, the composition of which is substantially SiO ₂ : 10 to 40 mol%,
B ₂ O _3: 10~40 mol%,
ZnO: 15-40 mol%,
Al ₂ O _3: 3~10 mol%,
Na ₂ O and / or _Li 2 O: 10 to 20 mol%,
CaO and / or BaO: 0 to 10 mol%,
Bi ₂ O ₃ : 0 to 20 mol%,
The glass powder which consists of a lead-free glass composition which is this ratio is mentioned, However, It is not limited to this composition. For example, if desired, one or more oxides selected from the group consisting of SnO, SnO ₂ , CuO, Cu ₂ O, TiO ₂ , ZrO ₂ and CeO ₂ can be included. Although the content is not particularly limited, for example, 10 mol% or less (preferably 5 mol% or less) of the entire glass composition is appropriate.

  The glass powder made of this type of lead-free glass composition for plasma display obtained by the production method of the present invention may have a softening point of preferably 560 ° C. or less, particularly preferably 550 ° C. or less (more preferably 540 ° C. or less). Moreover, high water resistance can be realized. Specifically, the weight loss rate after being immersed in warm water at 80 ° C. for about 15 hours (that is, the weight loss rate after immersion with respect to the weight before immersion in warm water) is reduced to 5% by mass or less, particularly 2% by mass or less. can do. Furthermore, the gas adsorption property can be extremely lowered. Specifically, after the glass powder is left in the air at room temperature for 100 hours and then heated to 600 ° C., the weight reduction rate (that is, the weight reduction rate when heated to 600 ° C. relative to the weight at room temperature) is 5 It can be reduced to not more than mass%, particularly not more than 2 mass%.

The glass powder obtained by the production method of the present invention can be made into a paste for various purposes in the same manner as the conventional glass powder. For example, a glass paste for forming a dielectric layer or a partition (for example, a transparent dielectric layer) at a predetermined portion of a plasma display is provided. Typically, a glass powder having a predetermined composition is coated, printed, or patterned with a paste in which a binder, an organic solvent (solvent), and other additives such as an inorganic filler and an inorganic pigment are mixed as necessary. By baking, a dielectric layer or a partition (for example, a transparent dielectric layer) can be formed.
Although there is no restriction | limiting in particular in the glass powder content rate in a glass paste, About 50-80 mass% of the whole glass paste, More preferably, it may be a content rate of 60-80 mass%, Especially preferably, it is 60-70 mass%.
Preferred binders include cellulose derivatives such as hydroxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, carboxymethylcellulose, carboxyethylcellulose, carboxyethylmethylcellulose, and the like. By using such a binder, a fired product having a particularly high transparency (for example, a transparent dielectric layer) can be formed. Although it does not specifically limit, It is preferable that a binder is contained in about 5-20 mass% of the whole glass paste.
In addition, examples of preferable organic solvents (solvents) include various ether solvents, ester solvents, ketone solvents, and other organic solvents. High boiling solvents such as terpineol are particularly suitable. Although it does not specifically limit, It is preferable that an organic solvent is contained in about 5-40 mass% of the whole glass paste.

  Using such paste, the transparent dielectric layer 6 of the plasma display panel 1 as shown in FIG. 1 can be formed by a method similar to the conventional method. For example, the glass paste is applied to the upper surface (upper surface including the Ag electrode 5) of the front glass plate 2 of the plasma display panel 1 by using a method such as a screen printing method, a bar coater method, a roll coater method, a blade coater method, or a die coater method. Then, a coated material having a film thickness of about 10 to 100 μm is formed. The coated material is dried at an appropriate temperature (about 80 to 120 ° C.) and then baked by holding it at a temperature of 500 to 600 ° C. for about 10 to 60 minutes to form the desired transparent dielectric layer 6. Can do.

  Moreover, the paste for forming the partition 4 of the plasma display panel 1, or the front or back glass plates 2 and 3 can also be prepared according to the composition of the glass powder to manufacture. Depending on the purpose, the binder, organic solvent, and other components (for example, Ag powder or other conductive metal powder for electrode formation) used in the paste are different and are appropriately selected from those conventionally known in paste production. It can be selected and used.

  EXAMPLES Examples relating to the present invention will be described below, but the present invention is not intended to be limited to those shown in the examples.

In this example, the dry pulverization process according to the present invention was performed using a dry pulverizer (media stirring mill) 50 having a configuration schematically shown in FIG.
As shown in FIG. 3, the apparatus used in this example is mainly composed of a commercially available media stirring mill 50 having the same configuration as that of the dry pulverizer 30 schematically shown in FIG. The capacity of the casing (grinding tank) 51 is about 100 L, and a jacket 67 through which chiller water circulates is attached to the outer wall portion (made of Al ₂ O ₃ ) of the casing 51. Thereby, the temperature inside the casing 51 can be kept constant (10 to 40 ° C.).
A medium (Al ₂ O ₃ or ZrO ₂ beads) 60 having a diameter of about 5 to 25 mm is accommodated in the bottom of the casing 51, and a multilayer rotating disk-shaped agitator 52 connected to a driving motor 62. Is arranged. On the other hand, a rotor 54 made of ZrO ₂ is disposed in the upper part of the casing 51 in a state where the rotor 54 is connected to the drive motor 64.

A raw material supply pipe 66 communicating with a raw material hopper and an electromagnetic feeder (not shown) is provided on the side wall of the casing 51, and a desired amount of vitreous material can be continuously supplied into the casing 51.
The casing 51 is connected to an air supply pipe 53 for introducing a gas flow into the casing 51 from the bottom of the casing. An injector 58 that communicates with a water tank (not shown) is provided in a part of the air supply pipe 53. Thereby, a desired amount of moisture can be supplied into the casing 31 together with the gas flow, preferably in the form of a mist or steam.
A HEPA filter 63 is attached to the upstream end of the air supply pipe 53 (that is, the air intake).
On the other hand, an exhaust pipe 55 for sending the classified glass powder to the outside of the casing together with the gas flow is connected to the rotor 54 at the upper part of the casing. The exhaust pipe 55 is connected to a cyclone (dust separator) 56 and a bag filter (dust collector) 57 provided outside the casing. Further, a blower 68 is provided downstream of the bag filter 57 in the exhaust pipe 55. By operating this blower 68, air is introduced into the air supply pipe 53 through the HEPA filter 63, and air can be introduced into the casing 51 at a flow rate of about 100 to 500 Nm ³ / h.

<Glass material (starting material)>
As a raw material powder (starting material) used in this example, general ZnO—Bi ₂ O ₃ —B ₂ O ₃ —SiO ₂ -based glass (ZnO: 20 to 40 mol%, Bi ₂ O ₃ : 0 to 20) _{mol%, B} 2 O 3: _{10~30 mol%,} SiO 2: 20 to 40 mol%) was prepared.

<Grinding of glassy material: Preparation of glass powder sample>
10 to 40 kg of the starting material was charged into a casing 51 in which 50 to 120 kg of the media (beads) 60 was put. And the water addition grinding process was first performed in the state with which the inside of the casing 51 was maintained at 10-40 degreeC with the said jacket 67. FIG.
Specifically, the motors 62 and 64 are driven to operate the agitator 52 (rotation speed: 30 to 270 rpm) and the rotor 54 (rotation speed: 1000 to 3600 rpm), and the blower 68 is used at a flow rate of 100 to 500 Nm ³ / h. Air was introduced into the casing 51. And the amount corresponding to 20% by mass (sample 1, sample 6), 40% by mass (sample 2, sample 7), or 60% by mass (sample 3, sample 8) of the total amount of the vitreous material finally charged. The pulverization process was performed while continuously supplying 5 to 60 minutes of water from the injector 58. As a comparative control, a pulverization treatment for 30 minutes was performed under the same conditions without adding water (Sample 4).

After completion of the water addition pulverization process for 5 to 60 minutes, the water supply was stopped and the pulverization process (that is, the water non-addition pulverization process) was continued for 5 to 90 minutes. In this non-moisture-added pulverization process, the vitreous material (powder) in the casing 51 is gradually dried and lightened, soars on the gas flow in the casing 51, passes through the rotor 54, and passes through the cyclone 56 (or bug). The filter 57) was able to separate and collect glass powder having an average particle size of about 1 μm.
A part of the obtained glass powder of each sample was further subjected to a drying treatment. Specifically, the sample was transferred to a ventilation heater (oven) and subjected to heat drying treatment at 70 to 140 ° C. for 1 to 12 hours (Sample 1A, Sample 2A, Sample 3A, Sample 6, Sample 7, Sample 8). ).
As a comparative example, the glassy material was put together with beads in an alumina container in a ball mill and wet pulverized at 200 rpm for about 15 to 20 hours to prepare glass powders having the same composition (Sample 5 and Sample 9).
The moisture content (average value) immediately after the moisture addition pulverization treatment of these samples is shown in the corresponding columns of Tables 1 and 2. The moisture content was determined from the change in weight before and after the drying treatment by drying 2 g of glass powder in a ventilation dryer at 80 ° C. until no weight loss was observed. It can be seen that the water content of the vitreous material (crushed material) in the casing 51 at the time when the water supply is stopped is maintained in the range of 0.5 to 30% by mass.
Also, immediately after the non-moisture-added pulverization process (Sample 1, Sample 2, Sample 3, Sample 6, Sample 7, Sample 8) and immediately after the heat drying process (Sample 1A, Sample 2A, Sample 3A, Sample 6, Sample 7, Sample 8) The water content (average value) of 8) is shown in the corresponding columns of Tables 1 and 2. It turns out that the moisture content of each obtained sample (glass powder) is in the range of 0.1 to 0.8 mass%.

<Production of glass paste (1)>
Using the glass powders of Samples 1 to 5 obtained as described above, transparent dielectric layer glass pastes corresponding to the respective samples were produced. Specifically, 50 to 70 parts by mass of glass powder, 10 to 20 parts by mass of a binder (carboxymethylcellulose), and 10 to 30 parts by mass of an organic solvent (terpineol) were mixed to prepare a glass paste.

<Evaluation test (1)>
The produced glass paste is applied on a front glass plate provided with an Ag electrode used for a plasma display panel by a screen printing method, held at 80 to 140 ° C. for 10 to 60 minutes and dried, and then at 500 to 600 ° C. Firing was performed for 10 to 60 minutes. The film thickness of the obtained transparent dielectric layer was about 20 μm.
About the transparent dielectric material layer obtained in this way, b value which shows the coloring degree of a glass plate was measured using the color difference meter. The linear transmittance was measured using a laser having a wavelength of 550 nm. In addition, withstand voltage performance was evaluated by AC measurement. These results (each average value) are shown in the corresponding column of Table 1.

  As is apparent from the results shown in Table 1, the transparent dielectric layer produced using the glass powder obtained by performing the two-step dry grinding of the water addition grinding treatment and the water non-addition grinding treatment according to the present invention is Compared with a transparent dielectric layer produced by using a glass powder obtained by conventional dry pulverization or wet pulverization, particularly excellent linear transmittance was exhibited. Moreover, the withstand voltage performance was the same level as that of the wet pulverization, which was comparable. Sample 2 (sample 2A) and sample 3 (sample 3A) show particularly excellent b values, and the total amount of added water is set to an amount corresponding to 40 to 60% by mass of the total amount of the vitreous material. It was confirmed that yellowing can be suppressed extremely effectively.

<Production of glass paste (2)>
Using the glass powders of Samples 6 to 9 obtained as described above, barrier rib glass pastes corresponding to the respective samples were produced. Specifically, 50-60 parts by mass of glass powder, 10-20 parts by mass of filler powder (alumina), 10-20 parts by mass of binder (ethylcellulose), 10-20 parts by mass of organic solvent (terpineol) are mixed to obtain a paste. Produced.

<Evaluation test (2)>
The produced glass paste for barrier ribs was applied by an applicator on the back glass plate on which the address electrode used for the plasma display panel and the white dielectric layer were formed, and dried at 120 ° C. for 30 minutes. The obtained dried film was baked at 500 to 600 ° C. for 10 to 60 minutes. The film thickness of the obtained fired film (partition wall layer) was about 100 μm.
About the baked film obtained in this way, L value was measured using the color difference meter, and the reflectance was computed.
Further, as a DFR adhesion test, a dry film resist (DFR) was laminated on the dry film, exposed, and developed with a sodium carbonate solution to form a pattern. When this was sandblasted, the width of the finest line with which the resist was in close contact was measured. These results (each average value) are shown in the corresponding column of Table 2.

  As is apparent from the results shown in Table 2, the partition wall layer produced using the glass powder obtained by performing the two-step dry pulverization process of the water addition pulverization process and the water non-addition pulverization process according to the present invention is conventionally used. Compared with the partition wall layer produced using the glass powder obtained by the wet pulverization, a reflectance comparable to that of the partition layer and the DFR fine wire adhesion were shown.

  As is clear from the above results, the use of the glass powder obtained by the glass powder manufacturing method of the present invention can prevent yellowing and provide a high-quality plasma display panel. For example, as is clear from this example, by using a glass powder for forming a transparent dielectric layer, when the film thickness is 20 μm, the linear transmittance is 85% or more, the average withstand voltage is 0.45 kV or more, and on the Ag electrode. A transparent dielectric layer having a high transmittance with a b value of 2 or less can be provided. Thereby, it is possible to provide a plasma display panel with high brightness and high image quality.

It is sectional drawing which shows the cell structure of a plasma display panel typically. It is explanatory drawing which shows typically the suitable apparatus structure for enforcing the glass powder manufacturing method of this invention. It is explanatory drawing which shows typically the apparatus structure used for implementation of the glass powder manufacturing method which concerns on one Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Plasma display panel 2 Front glass plate 3 Back glass plate 4 Partition 5 Display electrode (Ag electrode)
6 Transparent dielectric layer 30, 50 Media agitating mill 31, 51 Casing 32, 52 Agitator 33, 53 Air pipe 34, 54 Rotor 35, 55 Exhaust pipe 36, 56 Cyclone 37, 57 Bag filter 38, 58 Injector 40, 60 Media (beads)
63 HEPA filter 66 Supply pipe 68 Blower

Claims (4)

A method for producing glass powder with a dry grinding process,
The dry pulverization step includes
(1) In the casing of the pulverizer in which the vitreous material to be crushed is contained, the moisture is added until the final total amount of added water becomes an amount corresponding to at least 10% by mass of the total amount of the vitreous material accommodated. A moisture addition pulverization step in which pulverization is performed in the casing in a state of being ventilated while continuing the supply;
(2) a moisture non-addition crushing step of stopping the water supply after the total amount of added water reaches a predetermined value and continuing the same crushing process in the aerated casing;
The glass powder manufacturing method characterized by including. The total amount of added water is set to an amount corresponding to 20 to 60% by mass of the total amount of the vitreous material,
The moisture supply is performed such that the moisture content of the vitreous material in the casing at the time when the moisture supply is stopped is maintained in a range of 0.5 to 30% by mass. 2. The production method according to 1. A glass powder for forming a dielectric layer or barrier rib of a plasma display panel,
The glass powder manufactured by the manufacturing method of Claim 1 or 2 by using the vitreous material prepared by the oxide composition which can form the said dielectric material layer or a partition as a starting material. A glass paste for forming a dielectric layer or barrier rib of a plasma display panel,
A glass paste mainly composed of glass powder produced by the production method according to claim 1, wherein a glassy material prepared in an oxide composition capable of forming the dielectric layer or partition is used as a starting material.

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