JPH11236244A - Low melting point glass composition for coating electrode and plasma display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the transparency of a glass coating layer by incorporating the powder of low m.p. glass having a specified particle size distribution and a softening point lower than a specified temp. SOLUTION: This low m.p. glass compsn. has the particle size in which the 10% diameter under an integrated minus sieve is <=1.5 μm, the 50% diameter is 0.5-5.0 μm and the 90% diameter is <=10.0 μm and contains the powder of the low m.p. glass having a softening point lower than 480 deg.C. The low m.p. glass consists essentially of, by weight on the oxide basis, 52-68% PbO, 14-28% B2 O3 , 5-23% ZnO, 0-5% SiO2 , 0-8% Al2 O3 and 0-5% SnO2 . In a plasma display device, an electrode on the glass substrate of a front substrate is coated with the low m.p. glass layer made from the low m.p. glass compsn lower than 480 deg.C. The number of bubbles having >=10 μm diameter in the layer depending on the low m.p. glass is <=50 per the 1 mm<2> layer surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ITO (tin-doped indium oxide) or tin oxide (fluorine,
A low-melting glass composition suitable for insulatingly covering a transparent electrode such as antimony, including tin oxide doped with
And a plasma display device.

[0002]

2. Description of the Related Art In recent years, thin flat panel color display devices have attracted attention. In such a display device, an electrode must be formed in each pixel in order to control the display state of the pixel forming an image. A transparent electrode is used as such an electrode in order to prevent deterioration in image quality. As the transparent electrode, a thin film of ITO or tin oxide formed on the surface of a glass sheet is often used.

[0003] Such a transparent electrode is processed into a thin linear shape in order to realize a fine image, particularly in the display device. In order to control each pixel independently, it is necessary to ensure the insulation between the finely processed transparent electrodes. However, when moisture or an alkali component in the sheet glass exists on the surface of the sheet glass, a slight current may flow through the surface of the sheet glass. In order to prevent such a current, it is effective to form an insulating layer between the transparent electrodes. Further, in order to prevent deterioration of image quality due to the insulating layer formed between the transparent electrodes, the insulating layer is preferably transparent.

Various insulating materials for forming such an insulating layer are known, and among them, a glass material which is a transparent and highly reliable insulating material is widely used. As a method of coating using a glass material,
Although there is a method of forming a film under vacuum such as a sputtering method, a method of applying and firing a low-melting glass composition containing a low-melting glass powder is economically preferable.

In particular, a plasma display device (a cell is defined by a front substrate, a rear substrate, and a partition wall) which is expected to be a large flat color display recently, and an image is formed by generating a plasma discharge in the cell. In the front substrate of the display device), a glass coating layer having excellent plasma durability for protecting the transparent electrode from plasma is essential. Conventionally, such a glass coating layer is formed by applying a glass composition containing a glass powder on a glass substrate and firing the glass composition.

[0006]

The glass coating layer formed by applying a conventional glass composition on a glass substrate and firing the glass composition has a problem of low transparency. An object of the present invention is to provide a low-melting-point glass composition for electrode coating and a plasma display device that solve the above problems.

[0007]

According to the present invention, the 10% diameter under the integrated sieve is 1.5 μm or less, and the 50% diameter is 0.5 to 5.0.
Low melting glass composition for electrode coating, having a particle size of μm, a 90% diameter under an integrated sieve of 10.0 μm or less, and a powder of a low melting glass having a softening point lower than 480 ° C., and a front substrate In a plasma display device in which cells are defined by a back substrate and partition walls, the number of bubbles having a diameter of 10 μm or more in a glass layer made of a low melting point glass having a softening point lower than 480 ° C. A plasma display device in which an electrode provided on a glass substrate of a front substrate is coated with a glass layer of 50 or less per 1 mm ^{2 of the} surface of the glass layer, and cells are formed by the front substrate, the rear substrate, and the partition walls. Plasma display device has a softening point of 4
Provided is a plasma display device using a front substrate in which an electrode provided on a glass substrate of the front substrate is covered with a low-melting glass lower than 80 ° C. and a transmittance of light having a wavelength of 550 nm is 70% or more.

The present inventors have conducted intensive studies on a glass coating layer for insulatingly coating a transparent electrode, and as a result, have found that the transparency of the glass coating layer is greatly affected by bubbles in the glass coating layer. Furthermore, bubbles in the glass coating layer are not generated from the glass during firing of the glass composition, and voids between the glass particles existing in the coating layer of the glass powder before firing are caused by the softening flow of the glass particles during firing. The present inventors have found that the shape has become spherical with the completion of the present invention.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The integrated sieve below 10
% Diameter D ₁₀ represent respectively the particle diameters is the particle diameter corresponding to 10% of the volume-based, cumulative distribution curve representing the particle size distribution. Also, 50% diameter D ₅₀
Is 50% of the volume-based / integrated distribution curve representing the particle size distribution
Is the particle diameter. The 90% diameter D ₉₀ under the integrated sieve is 9% of the volume-based / integrated distribution curve representing the particle size distribution.
The particle diameter is equivalent to 0%.

The low-melting glass referred to in the present specification is a glass having a softening point of 620 ° C. or less, and the low-melting glass powder is a powder of such a low-melting glass. The low-melting glass composition referred to in the present specification comprises low-melting glass powder, an organic vehicle for imparting printability, and the like.

[0011] of the present invention, for covering electrodes low melting point glass composition, D ₁₀ is 1.5μm or less, D ₅₀ is 0.5~5.0μ
m, D ₉₀ contains a low-melting glass powder particle size is less, 10.0 [mu] m. D ₁₀ is greater than 1.5 μm, or D
_{When 50} is larger than 5.0 μm or D ₉₀ is larger than 10.0 μm, the gap between the glass particles of the low melting point glass powder in the coating layer formed by applying the low melting point glass composition increases. As a result, bubbles in the glass coating layer formed by firing increase. In addition, the cause of the increase in the gap between the glass particles in the coating layer of the low-melting glass powder is an increase in the glass particle diameter and a decrease in the filling rate of the glass particles. Also, D
_{If 50} is smaller than 0.5 μm, the time required for pulverizing the low-melting glass becomes too long, and the cost increases.

As a glass substrate on which electrodes are formed, 50
Glass substrates having an average linear expansion coefficient (hereinafter, referred to as a thermal expansion coefficient) α of ８０350 ° C. and 80 × 10 ^{-7 to} 90 × 10 ^-7 / ° C. are widely used. In such a case, as the low melting point glass powder of the low melting point glass composition, α is 70 × 10 ^{−7 to} 90 to match the expansion characteristics with the glass substrate and to prevent the warpage and strength of the glass substrate. × 1
It is preferable to use one having 0 ^-7 / ° C.

The low-melting glass composition for coating an electrode of the present invention forms a glass coating layer by coating it on a glass substrate and firing it.
It is preferable to carry out at the following firing temperature.

The low-melting glass composition for coating an electrode according to the present invention includes, as oxide-based weight percents, PbO: 52 to 68%, B ₂ O ₃ : 14 to 28%, ZnO: 5 to 23%, _{SiO 2: 0~ 5%, Al} 2 O 3: 0~ 8%, SnO 2: 0~ 5%, it is preferable to use a powder of low melting glass consisting essentially of.

PbO is an essential component for lowering the melting point of glass, and is preferably contained in an amount of 52 to 68%.
If the content is less than 52%, the softening point of the glass becomes high,
Baking at 620 ° C. or lower makes it difficult to form a sufficiently transparent layer. It is preferably at least 53%. On the other hand, when the content is 6
If it exceeds 8%, the coefficient of thermal expansion of the low-melting glass becomes too large, and the glass layer tends to be colored yellow. Preferably it is 64% or less.

B ₂ O ₃ is a component that makes the PbO-based low melting glass a stable glass, and preferably contains 14 to 28%. If the content is less than 14%, the low-melting glass may crystallize during firing and impair transparency. Also,
There is a possibility that the amount of PbO contained relatively becomes large and the thermal expansion coefficient of the low melting point glass becomes large. Content is 28
%, The content of PbO is relatively reduced, and the softening point of the low-melting glass may increase.

ZnO is a component for reducing the thermal expansion coefficient of the low-melting glass, and is preferably contained at 5 to 23%. If the content is less than 5%, the coefficient of thermal expansion of the low-melting glass may increase. It is preferably at least 9%. If the content is more than 23%, the low-melting glass may crystallize during firing and may impair transparency. Preferably 21%
It is as follows.

Although SiO ₂ is not an essential component, it can be added to make the PbO-based low-melting glass stable. 5
%, The softening point of the glass increases, which promotes crystallization of the low-melting glass during firing, and may impair transparency.
Further, the amount of PbO relatively contained may increase, and the coefficient of thermal expansion of the low-melting glass may increase.

Although Al ₂ O ₃ is not an essential component, PbO
The low-melting glass can be added to make the glass stable. If it exceeds 8%, crystallization of the low-melting glass during sintering is promoted, and the transparency may be impaired.

Although SnO ₂ is not an essential component, it can be added to oxidize carbon remaining in the glass and prevent coloring of the glass. If it exceeds 5%, the viscosity of the low-melting glass increases, making it difficult for air bubbles to float, which may impair transparency.

In the above glass composition, in addition to these components, MgO, CaO is used to adjust the thermal expansion coefficient, chemical durability, softening point, transparency, and stability of the low melting glass. , SrO, BaO, La ₂ O ₃ , T
iO ₂ , ZrO ₂ , CeO _2, etc. are set in a range that does not impair the effects of the present invention (preferably each of 10
% Or less). Li ₂ O, Na ₂
Alkali metal oxides such as O and K ₂ O, and halogen components such as F are components that lower the softening point of the glass and do not impair the electrical characteristics and the like (preferably 10% or less of the low melting point glass composition). May be added.

In the plasma display device of the present invention, the low melting point glass is made of low melting point glass having a softening point lower than 480 ° C., and bubbles having a diameter of 10 μm or more exist in the low melting point glass at 50 or less per mm ^{2 of the} low melting point glass layer surface. The electrode on the glass substrate of the front substrate is covered with the low melting point glass layer.

The diameter of the low melting point glass layer is 10 μm.
The number of the above bubbles is 5 per 1 mm ^{2 of the} surface of the low-melting glass layer.
The reason why the number is zero or less is as follows. That is,
The number of bubbles having a diameter of 10 μm or more is the low melting point glass layer surface 1
If the number is larger than 50 per mm ^2, the light transmittance of the glass layer is reduced, and the image quality of the plasma display device is reduced. In addition, bubbles existing in the glass are a major cause of dielectric breakdown, and the withstand voltage characteristics of the glass layer are reduced.

In another plasma display device of the present invention, an electrode provided on a glass substrate as a front substrate is covered with a low melting point glass having a softening point lower than 480 ° C., and has a transmittance of 70 nm at a wavelength of 550 nm. % Or more. By using such a front substrate, it is possible to prevent a decrease in image quality of the plasma display device.

In the plasma display device of the present invention, the low-melting glass composition for coating an electrode of the present invention is applied to an electrode such as a transparent electrode provided on a glass substrate as a front substrate, and then fired to obtain a transparent material. A glass coating layer having high properties can be formed.

[0026]

EXAMPLE Lead oxide, boric anhydride, zinc oxide, silica sand, aluminum oxide, and stannic oxide were mixed so as to have a composition (% by weight) as shown in Table 1, and the mixture was placed in a platinum crucible at 1300 ° C. For 1 hour, formed into a thin glass sheet, and then pulverized with a ball mill to obtain a low-melting glass powder. Table 1 shows the particle sizes D ₁₀ , D ₅₀ , D ₉₀ and the softening point (° C.) of the low-melting glass powder measured by a differential thermal analyzer. Further, after molding the low melting point glass powder, the fired body obtained by firing at 500 ° C. for 10 minutes is processed into a columnar shape having a diameter of 5 mm and a length of 2 cm, and a thermal expansion coefficient α of 50 to 350 ° C. Unit: × 10 ^-7
/ ° C) (α in Table 1).

100 g of the low-melting glass powder was kneaded with 25 g of an organic vehicle in which 7% by weight of ethyl cellulose was dissolved in diethylene glycol monobutyl ether acetate to prepare a paste ink.

Next, a film thickness of 200 nm and a width of 0.5 mm
75mm x 50m with ITO transparent electrodes
m, a glass substrate of soda lime glass having a thickness of 2.8 mm was prepared, and the paste-like ink was uniformly screen-printed on a 48 mm × 24 mm portion on the transparent electrode, and then heated at 120 ° C.
For 10 minutes. This glass substrate was heated at a rate of 10 ° C.
Per minute to the calcination temperature (° C.) shown in Table 1 and calcination by maintaining the temperature for 10 minutes. The thickness (μm) of the low-melting glass layer after firing was measured (low-melting glass layer thickness in Table 1). The light transmittance and the number of bubbles of the fired glass substrate were measured by the following methods. Table 1 shows the results.

Light transmittance: 550 wavelength using a self-recording spectrophotometer U-3500 (integrating sphere type) manufactured by Hitachi, Ltd.
Measure the transmittance of light in nm. 100 without sample
%, And the transmittance (%) of a sample obtained by firing a low melting point glass powder on a glass substrate was measured. If it is 70% or more, it passes. Number of bubbles: A photograph of the low-melting glass layer was taken at a magnification of 500 using an optical microscope (transmitted light), the number of bubbles in the obtained photograph was counted, and the number of bubbles per 1 mm × 1 mm surface of the glass layer (pieces / mm ² ).

[0030]

[Table 1]

[0031]

As described above, the low melting glass composition of the present invention can form a glass coating layer which is a transparent insulating layer without deteriorating the characteristics of various electrodes such as a transparent electrode such as ITO. Suitable for use. Further, in the plasma display device of the present invention, the image quality is not deteriorated by the glass coating layer that covers various electrodes such as the transparent electrode provided on the glass substrate of the front substrate.

Claims (5)

[Claims] 1. A 10% diameter under an integrated sieve is 1.5 μm or less,
The particle size is such that the 50% diameter is 0.5 to 5.0 μm, the 90% diameter under the integrated sieve is 10.0 μm or less, and the softening point is 48.
A low-melting glass composition for coating an electrode, comprising a low-melting glass powder lower than 0 ° C. 2. The composition of the low-melting glass has a weight percentage based on oxides.
In _{view, PbO: 52~68%, B 2} O 3: 14~28%, ZnO: 5~23%, SiO 2: 0~ 5%, Al 2 O 3: 0~ 8%, SnO 2: 0~ The low melting glass composition for electrode coating according to claim 1, which is substantially 5%. 3. A glass layer made of a low-melting glass having a softening point lower than 480 ° C. in a plasma display device in which cells are defined by a front substrate, a rear substrate and partition walls. A plasma display device in which an electrode provided on a glass substrate as a front substrate is covered with a glass layer in which the number of bubbles having a size of 10 μm or more is 50 or less per 1 mm ^{2 of the} surface of the glass layer. 4. In a plasma display device in which cells are defined by a front substrate, a rear substrate and partition walls, electrodes provided on a glass substrate of the front substrate are covered with a low-melting glass having a softening point lower than 480 ° C. And a plasma display device using a front substrate having a transmittance of light having a wavelength of 550 nm of 70% or more. 5. An electrode provided on a glass substrate of a front substrate is coated with a low-melting glass obtained by firing the low-melting glass composition for electrode coating according to claim 1 or 2, and a light having a wavelength of 550 nm is coated. A plasma display device using a front substrate having a transmittance of 70% or more.