JP2001072434A - Inorganic filler for compounding of glass paste - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a filler suitable for a partition wall, etc., requiring the formation of a substrate for a plasma display panel(PDP) and used for compounding of a glass paste containing an inorganic powder added to a glass material. SOLUTION: This inorganic filler comprises a magnesium titanate powder. The magnesium titanate powder preferably has >=0.1 and <=10 μm primary particle diameter according to a scanning type electron micrograph(SEM) photograph and >=0.1 and <=10 m2/g BET specific surface area. The glass paste is obtained by adding and mixing an organic substance with a composition prepared by compounding a low-melting glass powder having <=500 deg.C glass transition point with >=1 and <=80 wt.% of the above magnesium titanate powder. The plasma display panel uses the glass paste.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a filler for compounding a glass paste obtained by adding an inorganic powder to a glass material, which is suitable for a partition wall or the like required to be formed on a substrate of a plasma display panel (hereinafter referred to as PDP).

[0002]

2. Description of the Related Art A PDP is a thin and lightweight display panel capable of realizing a large screen, and is expected to be used for a large-screen television or a wall-mounted television in the future.
One of the current problems with panels is lack of screen brightness, and various proposals for improving brightness have been made. For example, a method of applying a phosphor and forming a partition has been studied. The partition walls are made of glass, and are formed by molding, firing, and densifying glass powder. Filling glass powder with an inorganic powder such as alumina or zircon has been conventionally proposed. However, the purpose of adding these inorganic powders was to keep the glass in a molten state in the step of firing after molding the partition walls with glass powder.

On the other hand, if the reflectance of the partition wall formed of glass powder can be improved, light emitted from the phosphor applied to the partition wall surface can be efficiently used for display, and the screen can be substantially reduced. Can be improved. By using an inorganic powder having a higher refractive index than alumina or zircon as a filler for the glass of the partition wall, the light emitted from the phosphor behind the panel at the partition wall is reflected and scattered by the high refractive index filler particles toward the front of the panel, Brightness may be improved. The idea of using titanium oxide having a refractive index as high as 2.6 as a reflector is disclosed in, for example, Japanese Patent Application Laid-Open No. H8-32257, "In order to effectively guide the light emission of the phosphor to the front surface of the panel, the partition walls are made white on the contrary. In this case, titania or the like is used as a fire-resistant white pigment. "However, titanium oxide (titania) has a relative dielectric constant of rutile type and is 100 to 100%.
110, 50 for anatase type, and high dielectric constant as PDP partition wall filler. In PDPs, studies have been made to reduce the electric capacity of the cells of the PDP, and a low dielectric constant is also required for the partition wall filler. In addition, by using a material having a higher refractive index than alumina or zircon and a lower dielectric constant than titanium oxide as a filler for the glass of the partition walls, the light emitted from the phosphor behind the panel at the partition walls has high refractive index filler particles. By reflecting and scattering to the front of the panel by
In addition, the possibility of reducing the electric capacity of the cell is assumed.
Conventionally, silica, alumina, titania, and zircon have been studied as fillers, but none of them has sufficient high refractive index and low dielectric constant.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a PD
An object of the present invention is to provide a glass paste compounding filler obtained by adding an inorganic powder to a glass material and suitable for a partition wall or the like that needs to be formed on a P substrate.

[0005]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, have found that magnesium titanate has a high refractive index, a specific particle diameter and a BET.
The present inventors have found that a magnesium titanate powder having a specific surface area is suitable as a filler material for a glass paste for forming a rib of a plasma display panel partition wall, and completed the present invention.

That is, the present invention provides the following (1) to (6)
I will provide a. (1) An inorganic filler for blending a glass paste, comprising a magnesium titanate powder. (2) The magnesium titanate powder has a primary particle size of 0.1 μm or more and 10 μm or less in a SEM photograph, and a BET
The inorganic filler for blending glass paste according to the above (1), having a specific surface area of 0.1 m ² / g or more and 10 m ² / g or less. (3) The inorganic filler for blending glass paste according to the above (2), wherein the magnesium titanate powder has a value obtained by dividing the primary particle size in the SEM photograph by the primary particle size calculated from the BET specific surface area is 0.1 or more and 5 or less. (4) The inorganic filler for blending glass paste according to the above (2) or (3), wherein the particles of the magnesium titanate powder have a polyhedral shape having substantially no crushed surface. (5) A glass paste obtained by adding an organic substance to a composition obtained by mixing the magnesium titanate powder of (2) with 1 wt% to 80 wt% of low melting glass powder having a glass transition point of 500 ° C. or less and 1 to 80 wt%. . (6) A plasma display panel using the glass paste according to (5).

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. The relative permittivity of magnesium titanate is 18 (literature value)
As a result of measuring the refractive index, a high value of 2.2 to 2.3 was obtained, and it was confirmed that the refractive index was high, and it was found that magnesium titanate can be used as a PDP partition material filler. However, considering the mixing with the glass powder as the PDP partition wall material, the difference in particle diameter from the glass powder is small, and the primary particle diameter in the SEM photograph is from 0.1 μm to 10 μm.
m or less, preferably 0.3 to 5 μm
Range. If it is less than 0.1 μm or more than 10 μm, mixing with glass powder may not be performed properly. Although the particle shape is more suitable for reflection and scattering than a spherical shape, a polyhedral shape is preferable.

[0008] A low BET specific surface area range, which indicates that the particles are large and the particle surface has few irregularities, ie, 0.1
m is preferably from ² / g or more 10 m ² / g, 0.3 to 5 m
² / g is more preferred. When the particle diameter calculated from the BET specific surface area is 10 μm, the BET specific surface area is 0.1 m ² /
g, the BET specific surface area is 0.1 m ² / g or more.

[0009] Magnesium titanate with a small amount of aggregated particles, wherein the value obtained by dividing the primary particle size in the SEM photograph by the primary particle size calculated from the BET specific surface area is 0.1 to 5 and preferably 0.5 to 1.5. Powders are preferred. BET
To calculate the particle size from the specific surface area, 6 (constant) ÷ 3.9
(Theoretical density of magnesium titanate is g / c
m ³ ) ÷ BET specific surface area (m ² / g). When there are many agglomerated particles, the surfaces of the particles are connected to each other, so that the surface area becomes small. As a result, the value obtained by dividing the primary particle size in the SEM photograph by the particle size calculated from the BET specific surface area becomes small. Is desirable, and 0.
5 or more is more desirable. Agglomerated particles cause defects in the partition walls when the partition walls are formed. On the other hand, when the particle shape is irregular, the surface has many defects, and when there are many irregularities, the value obtained by dividing the primary particle size in the SEM photograph by the particle size calculated from the BET specific surface area becomes large, and is preferably 3 or less, and 1.5 or less. The following are more preferred. If there are many defects and many irregularities on the particle surface,
The light reflection effect is not sufficiently exhibited.

Regarding the particle shape, a polyhedral shape which is not spherical and has substantially no crushed surface suitable for reflection and scattering is preferred. The polyhedral particles are realized by particles made of a single crystal of magnesium titanate. In a single crystal particle, a crystal plane resulting from the arrangement of atoms appears on the particle surface, giving the particle a polyhedral shape. Since the shape of magnesium titanate is basically a rectangular parallelepiped, the number of faces is six or more. If the number of faces exceeds 30, the shape becomes nearly spherical, and light reflection does not differ from spherical particles.

The titanium magnesium oxide powder of the present invention comprises:
It can be manufactured as follows. For example, a raw material for firing can be obtained by mixing magnesium oxide powder or magnesium hydroxide powder with anatase or rutile type titanium oxide powder. Alternatively, a raw material for firing can be obtained by mixing magnesium chloride or magnesium sulfate with anatase or rutile type titanium oxide powder in a wet manner, and drying the mixture. By firing the raw material for firing in the temperature range of 600 to 1200 ° C. in the air, a target titanium magnesium oxide powder is produced.

Further, the magnesium titanate powder used in the present invention can be produced as follows. Titanium compounds that can be converted to titanium oxide by heating, such as powder obtained by drying metatitanic acid slurry generated in the process of manufacturing titanium oxide by the sulfuric acid method and orthotitanic acid generated by neutralization or hydrolysis of an aqueous solution of titanium tetrachloride. Is mixed with magnesium hydroxide, and in an atmosphere containing 1% by volume or more, desirably 10% by volume or more of hydrogen chloride, 600 to 1200
C., preferably at a temperature in the range of 800 to 1100 ° C., preferably for 10 minutes to 6 hours.

For the firing, a batch-type firing furnace, a tunnel furnace, and a rotary kiln, which are industrially used, can be used as long as the furnace can control the gas atmosphere. When the obtained particles are large, by mixing the fine magnesium titanate powder with the raw material for firing, the fine magnesium titanate powder particles act as seed crystals and can reduce the particle diameter. The larger the amount of fine magnesium titanate powder added, the smaller the particle size.

The method of mixing the magnesium titanate powder into the glass paste for forming the partition walls is not particularly limited. A mixing method using a mixer equipped with a high-speed stirring blade such as a mixer or a medium such as a ball mill can perform dry mixing or wet mixing with addition of water or an organic solvent.

[0015]

EXAMPLES Examples of the present invention will be described below, but the present invention is not limited to these examples.

Various measurements in the present invention were performed as follows. 1. Primary particle size by SEM photograph SEM (scanning electron microscope, manufactured by JEOL Ltd .: T-
220), a photograph of the powder was taken, 5 to 10 particles were selected from the photograph, the size was measured, and the average value was determined. 2. BET Specific Surface Area BET specific surface area was measured by BET one-point method using Flowsorb II2300 manufactured by Micromeritics.

Example 1 A magnesium titanate powder was prepared as follows. 4645 g of water was added to 5223 g of an aqueous solution of titanium tetrachloride manufactured by Sumitomo Sitix. Titania STR- made by Sakai Chemical Industry
Weigh 1.4 g of 60N (trade name), add hydrochloric acid and adjust pH
Was added to 70 g of water adjusted to 2, and dispersed by an ultrasonic homogenizer, and then the dispersion was added to an aqueous titanium tetrachloride solution. A pH electrode and a stirrer were attached to a reaction vessel containing 3.3 kg of water, and the titanium tetrachloride aqueous solution was dropped by a tube pump, and the pH electrode was set to pH = 2.
Another tube pump was controlled by connecting to a pH controller set at 7, and a 48% by weight aqueous sodium hydroxide solution was dropped into the reaction vessel to carry out a neutralization precipitation reaction at pH = 2.7. Stirring was continued after the reaction was completed, and the stirring was stopped one hour later. The reaction solution after the neutralization precipitation is a state in which a white precipitate is dispersed, and a cake of the precipitate is obtained by suction filtration using a filter paper, and the cake is washed by pouring water thereon and performing suction filtration. did. The obtained washed cake was dried by a dryer set at 130 ° C. to obtain a dried cake. To 10.9 g of the obtained dried cake, 8.0 g of magnesium hydroxide and 25 g of isopropyl alcohol were added, and 250 ml together with a plastic ball containing an iron core were added.
The mixture was placed in a polyethylene wide-mouth bottle and mixed with a ball mill for 2 hours. The obtained slurry was dried using a rotary evaporator to obtain a powder before firing. 4 g of the powder before firing was charged into an alumina boat and fired in a furnace having a quartz glass furnace core tube. The heating rate was 10 ° C./min. From 400 ° C., HCl gas was 30 ml / min and nitrogen was 7
0 ml / min (HCl concentration 30% by volume), 950
After holding at 30 ° C. for 30 minutes, HCl gas and nitrogen gas were stopped, and air was allowed to flow at 100 ml / min to cool.

The obtained powder was examined by X-ray diffraction. As a result, the powder was found to be composed of a single phase of MgTiO ₃ . It mainly consisted of polyhedral particles, and the average particle diameter obtained from the SEM photograph was 1.8 μm. BET specific surface area is 0.54m
² / g. The particle diameter was calculated from the literature value of 3.9 g / cm ^{3 of} magnesium titanate and the BET specific surface area to be 2.8 μm, (average particle diameter by SEM photograph) /
(Particle size calculated from the BET specific surface area) was 0.6.

The glass addition test can be performed as follows. 2 g of the obtained magnesium titanate powder and Asahi Glass glass powder ASF having a low glass transition point of 420 ° C.
8 g of -1340 (trade name) is added to an alumina ball and 250 g.
Mix in a ball mill for 1 hour using a ml polyethylene jar. The obtained mixed powder is press-formed into a pellet at a pressure of 300 kg / cm ² using a 13 mmφ mold. Baking is performed at 600 ° C. for 20 minutes in air at a rate of 5 ° C./min. The relative permittivity of the obtained pellet can be calculated by a known calculation formula (Barium Titanate Practical Use Study Group Annual Report XIV-7)
4-Special "Recently Crystallized Glass" Sakuhana Saio, page 18, D
It is 14 when calculated using the formula).

Example 2 The powder before firing (mixture of titanium tetrachloride precipitate and magnesium hydroxide) used in Example 1 was used in the same furnace as in Example 1 except that the firing temperature was 1100 ° C. It baked on the same conditions. The powder obtained was examined by X-ray diffraction. As a result, it was confirmed that the main phase was MgTiO _3, but MgTi ₂ O ₅
Was a mixed powder. It mainly consisted of polyhedral particles, and the average particle diameter obtained from the SEM photograph was 5.1 μm. The BET specific surface area was 0.42 m ² / g. B
The particle size calculated from the ET specific surface area was 3.7 μm,
(Average particle size by SEM photograph) / (particle size calculated from BET specific surface area) is 1.4. The refractive index was measured using the obtained powder. The refractive index was measured to be 2.2 to 2.3 by embedding in a medium having a high refractive index and observing a Becke line with an optical microscope. The obtained magnesium titanate powder can be mixed with low melting point glass and fired in the same manner as in Example 1. The relative permittivity of the obtained pellet is calculated to be 14.

Example 3 The powder before calcining used in Example 1 (with titanium tetrachloride precipitates)
A mixture of magnesium hydroxide) in the same furnace as in Example 1.
Using a heating rate of 10 ° C./min and air of 100 ml / min.
The mixture was baked at 1100 ° C. for 30 minutes while flowing separately. The resulting powder
The end was examined by X-ray diffraction and found to be MgTiO_ThreeIs the main phase
But the intensity ratio of the main peak is MgTiO_Three: Mg
Ti_TwoO_Five: TiO_Two= 93: 2: 5
Was. The average particle size obtained from the SEM photograph was 0.51 μm.
there were. BET specific surface area is 2.1m ^Two/ G. B
The particle size calculated from the ET specific surface area is 0.73 μm,
(Average particle size by SEM photograph) / (From BET specific surface area)
(Calculated particle size) is 0.7. The resulting titanate mug
Nesium powder was mixed with low melting glass in the same manner as in Example 1.
Can be fired. Relative permittivity of obtained pellet
Is calculated to be 14.

Example 4 10 L of 462 g of commercially available anatase type titanium oxide powder, A-100 (trade name) manufactured by Ishihara Sangyo Co., Ltd., and 344 g of high purity magnesium hydroxide 200-06H (trade name) manufactured by Kyowa Chemical Co., Ltd. The resultant was put in a polyethylene container together with 9.7 kg of plastic balls containing an iron core, and mixed in a dry ball mill for 2 hours. The powder removed from the ball mill was placed in an alumina container and fired in air at 1100 ° C. for 1 hour. Jet mill PJM-100S manufactured by Nippon Pneumatic Industrial Co., Ltd.
Using a P-type, pulverization was performed under the conditions of air pressure of 6 kg / cm ² . As a result of examining the obtained powder by X-ray diffraction, only MgTiO ₃ was found. The average particle size obtained from the SEM photograph was 0.42 μm. The BET specific surface area was 3.7 m ² / g. The particle size calculated from the BET specific surface area was 0.42 μm, and (average particle size based on SEM photograph) / (particle size calculated from BET specific surface area) was 1.0.
Becomes 2 g of the obtained magnesium titanate powder and 8 g of glass powder ASF-1340 (trade name) manufactured by Asahi Glass Co., Ltd. having a low glass transition point of 420 ° C. were ball milled for 1 hour using alumina balls and 250 ml polyethylene wide-mouth bottles. did. The obtained mixed powder was press-formed into a pellet at a pressure of 300 kg / cm ² using a 13 mmφ mold. Baking was performed at 600 ° C. for 20 minutes in air at a temperature rising rate of 5 ° C./min. The relative permittivity of the obtained pellet was measured using an RF impedance analyzer 4291A manufactured by Hewlett-Packard Company, USA and a sample holder 16453.
As a result of measurement using A, the relative dielectric constant at 10 MHz was 14.7, and the dielectric loss at 15 and 10 MHz was 0.0017 even at 1 MHz and 0.0017. The calculated value of the relative permittivity is 14.

Comparative Example 1 A commercially available rutile type titanium oxide powder, CR-EL (trade name) manufactured by Ishihara Sangyo Co., Ltd. (BET specific surface area: 6.8 m ²
/ G, the particle size calculated from the BET specific surface area is 0.21 μm.
m, particle size of 0.2 μm by SEM) was mixed with low-melting glass in the same manner as in Example 1 and fired. The density of the obtained pellets was 4.92 g / cm ³ (relative density 98.8%). When the relative dielectric constant of rutile is set to 100 and the relative dielectric constant of the pellet is calculated in the same manner as in Example 1, it is 21. The relative permittivity at 10 MHz was measured in the same manner as in Example 4, and was found to be 20 at 20.1 and 1 MHz.

[0024]

Table 1 SEM diameter BET particle diameter / glass addition Glass addition (μm) (μm) ε calculated value ε measured value Example 1 1.8 2.8 0.6 14 Example 2 5.1 3.7 1.7. 414 Example 3 0.51 0.73 0.7 14 Example 4 0.42 0.42 1.0 14 14.7 Comparative Example 1 0.2 0.21 1.0 21 20.1

[0025]

According to the present invention, it is possible to provide a filler for a glass paste for forming ribs on a plasma display panel partition wall suitable for a plasma display panel.

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Claims (6)

[Claims] An inorganic filler for blending a glass paste, comprising a magnesium titanate powder. 2. The magnesium titanate powder has a primary particle size of 0.1 μm or more and 10 μm or less according to a SEM photograph,
Glass paste blend inorganic filler according to claim 1, wherein BET specific surface area is less than 0.1 m ² / g or more 10 m ² / g. 3. The magnesium titanate powder has a value obtained by dividing a primary particle size in an SEM photograph by a primary particle size calculated from a BET specific surface area is 0.1 or more and 5 or less.
An inorganic filler for blending glass paste as described in the above. 4. The inorganic filler for blending glass paste according to claim 2, wherein the particles of the magnesium titanate powder have a polyhedral shape having substantially no crushed surface. 5. The low melting point glass powder having a glass transition point of 500 ° C. or lower is obtained by adding the magnesium titanate powder of claim 2 to 1
A glass paste in which an organic substance is added to and mixed with a composition containing at least 80% by weight and not more than 80% by weight. 6. A plasma display panel using the glass paste according to claim 6.