JP2008030994A - Bismuth-based lead-free powdered glass - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bismuth-based lead-free powdered glass which is used for the formation of dielectric layers or barrier ribs for flat display panels such as PDP's, is capable of being fired on glass plates such as high strain point glass plates and is inhibited in the formation of bubbles on firing. <P>SOLUTION: The bismuth-based lead-free powdered glass is composed of a bismuth-based lead-free glass containing, in terms of oxide equivalent mass%, 30-75% Bi<SB>2</SB>O<SB>3</SB>, 1-15% SiO<SB>2</SB>, 5-20% B<SB>2</SB>O<SB>3</SB>, 2-8% ZrO<SB>2</SB>, 0-5% Al<SB>2</SB>O<SB>3</SB>, 0-30% ZnO, 0-5% TiO<SB>2</SB>and 0-15% one or more of CaO, MgO, SrO and BaO in total. The bismuth-based lead-free glass is pulverized into a powder having a 50% value on the volume-based cumulative particle distribution curve of less than 2.0 μm. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a bismuth-based lead-free powder glass used for forming a dielectric layer or partition of a flat display panel such as a plasma display panel.

  Due to the increasing demand for space saving and energy saving in recent years, flat display panels have been used in place of cathode ray tube image display devices (hereinafter also referred to as “CRT”), for example, plasma display panels (hereinafter referred to as “PDP”). And field emission displays are widely used.

In this PDP, two glass substrates each having an electrode or the like formed on the surface of a glass plate are used with the front and back sides facing each other.
In the PDP, usually, electrodes are formed in a stripe shape on a glass substrate on the back side, and a partition made of glass is provided between the electrodes. In addition, electrodes are formed in stripes on the front glass substrate surface in a direction perpendicular to the back electrodes, and the front electrodes and back electrodes are usually made of a glass layer called a dielectric layer. It is covered. The dielectric layer (front dielectric layer) of the front glass substrate is supported by the partition wall in a state of being separated from the dielectric layer (back dielectric layer) of the rear glass substrate. A space is defined by the back dielectric layer and the barrier ribs, and a phosphor is arranged in the space to form a display cell. The phosphor of the display cell is caused to emit light by plasma discharge between the front and back electrodes. Is displayed.

This dielectric layer and partition walls are usually formed of a material such as a glass paste or a green sheet mixed with a resin component and glass (powder glass) formed into a powder and, if necessary, a filler such as Al ₂ O _3. Has been. For example, these dielectric layers and barrier ribs may be baked after patterning by a screen printing method using glass paste, a photosensitive method using glass paste or a green sheet, or a film using a glass paste or a green sheet. After being formed into a film and fired, it is formed by patterning by a sandblasting method or a chemical etching method.

By the way, normally, the glass plate used for the front and back glass substrates of this PDP is soda lime glass or high strain point glass with reduced alkali content. Therefore, the powder glass used for the dielectric layer and the partition walls is usually one that can be fired on a glass plate such as this high strain point glass, and it is required to use a glass with a lower softening point. Yes.
In addition, for example, when bubbles are formed in the dielectric layer after firing, there is a risk of causing poor insulation, and when bubbles are formed in the partition walls, chipping or partial strength may occur. Therefore, there is a demand for powder glass used for the dielectric layer and partition walls that can be fired at a low temperature and can be fired more uniformly and densely.

As the glass having a low softening point used for the dielectric layer and the partition wall, a glass mainly composed of PbO has been used as described in Patent Document 1 below.
In recent years, in order to improve environmental awareness, there is a demand for lead-free electrical and electronic equipment, and bismuth-based lead-free glass is used instead of glass containing PbO as a main component.
However, powder glass using bismuth-based lead-free glass (bismuth-based lead-free powder glass) is difficult to sufficiently suppress the formation of bubbles and the like while sufficiently lowering its softening point. Nothing has been found that satisfies the above demands required for use in forming a layer or partition.
Such a problem is common to not only PDPs but also flat display panels in which a dielectric layer or barrier ribs are formed by firing bismuth-based lead-free powdered glass on a glass plate using high strain point glass or the like. It is.

JP-A-8-119725

  In view of the above problems, the present invention can be fired on a glass plate using a high strain point glass or the like as a bismuth-based lead-free powder glass used for forming a dielectric layer or partition of a flat display panel such as a PDP. However, it is an object to provide a bismuth-based lead-free powder glass that can suppress the formation of bubbles during firing.

  As a result of intensive studies on the bismuth-based lead-free powder glass used for forming the dielectric layer or partition of the flat display panel, the present inventors have found that a predetermined component is used in a predetermined amount as a component of the bismuth-based lead-free powder glass. In addition, by forming the bismuth-based lead-free powder glass on a glass plate using a high strain point glass or the like, it is possible to suppress the formation of bubbles during firing by forming the powder into a powder having a predetermined particle size. As a result, the present invention has been completed.

That is, the present invention has been made to solve the above-mentioned problems, and the invention according to claim 1 concerning bismuth-based lead-free powder glass is formed into a powder form using bismuth-based lead-free glass, and is a flat display. A bismuth-based lead-free powder glass used for forming a dielectric layer or partition wall of a panel, and Bi ₂ O ₃ : 30 to 75%, SiO ₂ : 1 to 15%, B ₂ O _{3 in} terms of mass% in terms of oxide. _{: 5~20%, ZrO 2: 2~8} %, Al 2 O 3: 0~5%, ZnO: 0~30%, TiO 2: 0~5%, and, CaO, MgO, SrO, of BaO 1 Bismuth-based lead-free glass containing 0-15% in total is used, and the 50% value of the volume-based cumulative particle size distribution curve is less than 2.0 μm. It is characterized by
In the present specification, the “volume-based cumulative particle size distribution curve” can measure the sphere equivalent diameter of a particle such as a laser diffraction / scattering particle size measuring device, and the distribution of the equivalent sphere diameter. Is intended to be measured using a device capable of measuring as a cumulative particle size distribution curve, and "50% value of volume-based cumulative particle size distribution curve" is a point at which the cumulative particle size distribution curve has a value of 50% Is intended for a sphere equivalent diameter. This “50% value of the volume-based cumulative particle size distribution curve” can be measured using, for example, a laser diffraction / scattering particle size analyzer (trade name “MICROTRAC HRA MODEL: 9320-X100”) manufactured by Nikkiso Co., Ltd. it can.

The invention according to claim 2 concerning the bismuth-based lead-free powder glass is the oxide according to claim 1, wherein the Bi ₂ O ₃ content is 30 to 50% and the SiO ₂ It is characterized in that the content of is ₂ to 10%, the content of B ₂ O ₃ is 10 to 20%, and the content of ZnO is 0 to 25%.
The invention according to claim 3 is characterized in that, in the invention according to claim 1 or 2, a 90% value of the volume-based cumulative particle size distribution curve is less than 5.0 μm, and according to claim 4, The invention is characterized in that, in the invention according to any one of claims 1 to 3, a temperature difference between a softening point and a glass transition point of the bismuth lead-free glass is 60 to 80K.
This “90% value of the volume-based cumulative particle size distribution curve” is also equivalent to the sphere equivalent diameter at the point where the cumulative particle size distribution curve has a value of 90%, similar to the above “50% value of the volume-based cumulative particle size distribution curve”. And can be measured using a Nikkiso Co., Ltd. laser diffraction / scattering particle size analyzer (trade name “MICROTRAC HRA MODEL: 9320-X100”).

The invention according to claim 5, which includes a bismuth-based lead-free powder glass and a filler, and relates to a back dielectric layer forming material used for forming a back-surface dielectric layer of a flat display panel. The bismuth-based lead-free glass according to any one of Items 1 to 4, wherein the filler is one or more of Al ₂ O ₃ , TiO ₂ , ZnO, SiO ₂ , ZrO ₂ , and MgO. The ratio of the filler to the total amount of the bismuth-based lead-free powder glass and the filler is 1 to 40% by mass.

Moreover, the invention according to claim 6, which includes a bismuth-based lead-free powder glass and a filler and is used for forming a partition wall of a flat display panel, is the bismuth-based lead-free powder glass according to any one of claims 1 to 4. The bismuth-based lead-free glass according to claim 1 is used, and the filler is one or more of Al ₂ O ₃ , TiO ₂ , ZnO, SiO ₂ , ZrO ₂ , MgO, and the bismuth-based glass The ratio of the filler to the total amount of the lead-free powdered glass and the filler is 1 to 40% by mass.

According to the present invention, Bi ₂ O ₃ : 30 to 75%, SiO ₂ : 1 to 15%, B ₂ O ₃ : 5 to 20%, ZrO ₂ : _{2~8%, Al 2 O 3:} 0~5%, ZnO: 0~30%, TiO 2: 0~5%, and, CaO, MgO, SrO, 0~15 % with one or more the sum of BaO Because the low softening point bismuth-based lead-free glass contained is used, high strain point glass, etc. was used when using bismuth-based lead-free powdered glass for the formation of dielectric layers or barrier ribs for flat display panels. It can be made bakable on a glass plate.

  Moreover, since the bismuth-based lead-free powder glass is formed in a powder form in which the 50% value of the volume-based cumulative particle size distribution curve is less than 2.0 μm, the formation of bubbles during firing can be suppressed.

  That is, according to the present invention, while firing is possible on a glass plate using a high strain point glass or the like as required in the formation of a dielectric layer or partition of a flat display panel such as a PDP, It is possible to provide a bismuth-based lead-free powder glass in which the formation of bubbles at the time is suppressed.

  Hereinafter, a preferred embodiment of the present invention will be described by taking bismuth-based lead-free powder glass used for PDP as an example.

The bismuth-based lead-free powder glass of the present embodiment is used for forming a dielectric layer and partition walls on the front side and the back side of the PDP. And the bismuth-type lead-free powder glass of this embodiment is formed in the powder form from which the 50% value of the volume-based cumulative particle size distribution curve will be less than 2.0 micrometers with a bismuth-type lead-free glass.
In this bismuth-based lead-free glass, Bi ₂ O ₃ : 30 to 75%, SiO ₂ : 1 to 15%, B ₂ O ₃ : 5 to 20%, ZrO ₂ : It comprises 2-8%, as optional components, in terms of oxide mass% in _{Al 2 O 3: 0~5%,} ZnO: 0~30%, TiO 2: 0~5%, and, CaO, MgO, SrO One or more kinds of BaO are contained in a total of 0 to 15%.
As this bismuth-based lead-free glass, because it is fired on a glass plate using high strain point glass or the like, it is usually set to a softening point of 600 ° C. or less due to the above components, and is deformed into a glass plate. It has a softening point of 580 ° C. or lower, and more preferably a softening point of 560 ° C. or lower, in that it can be fired on a glass plate while reducing the possibility of generating odor.

The Bi ₂ O ₃ is an essential component for obtaining the bismuth-based lead-free powder glass of the present invention, and the content of the Bi ₂ O ₃ is 30% to 75% by mass% because the content is less than 30%. In this case, the softening point of the obtained bismuth-based lead-free glass becomes high. For example, the softening point exceeds 600 ° C., and the bismuth-based lead-free powder glass is fired on a glass plate using a high strain point glass or the like. This is because it becomes difficult. On the other hand, if the content exceeds 75%, the thermal expansion coefficient becomes too large, causing cracks during firing or crystallization, which is not preferable.
The Bi ₂ O ₃ content is preferably 30 to 60%, more preferably 30 to 50%, in that the increase in softening point, cracking, and crystallization can be reliably prevented.

SiO ₂ is an essential component for expanding the vitrification range and stabilizing the glass, and the content of SiO ₂ is 1 to 15% by mass in the range of bismuth. This is because lead-free glass is stable and easy to fire. If the lower limit is less than 1%, the bismuth-based lead-free glass becomes unstable, and the durability of the material against environmental changes such as moisture in the air and durability against modification (hereinafter also referred to as “chemical durability”) Becomes worse. When this chemical durability deteriorates, for example, when the surface of the bismuth lead-free powder glass is altered or modified by moisture in the air, a glass paste using this bismuth lead-free powder glass is produced. There is a possibility that problems such as change in workability and change in sinterability at the time of firing tend to easily cause residual bubbles. On the other hand, when the content exceeds 15% which is the upper limit, the softening point of the bismuth-based lead-free glass becomes high, and the bismuth-based lead-free powder glass can be fired on a glass plate using a high strain point glass or the like. This is because it becomes difficult.
The content of SiO ₂ is preferably 1 to 13%, more preferably 1 to 10%, in order to ensure both the stabilization of the glass and the suppression of the increase in the softening point. .

B ₂ O _{3 is} also an essential component for obtaining the bismuth-based lead-free powder glass of the present invention, and is effective in stabilizing the glass. Further, compared with SiO ₂ , B ₂ O ₃ is effective in lowering the softening point of bismuth-based lead-free glass. Are better. The content of B ₂ O ₃ is set to 5 to 20% by mass. When the content of B ₂ O ₃ is less than 5%, the resulting bismuth-based lead-free glass becomes unstable. There is a fear. Further, when the content exceeds 20%, the softening point of the bismuth-based lead-free glass obtained becomes high, and it becomes difficult to fire the bismuth-based lead-free powder glass on a glass plate using high strain point glass or the like. Because.
The content of B ₂ O ₃ is preferably 10 to 20% in that both the stabilization of the glass and the suppression of the increase in the softening point can be ensured.

ZrO _{2 is} also an essential component for obtaining the bismuth-based lead-free powder glass of the present invention, and is effective in adjusting the viscosity and thermal expansion coefficient of the glass. When the content is less than 2%, the bismuth-based lead-free glass cannot be adjusted to an appropriate viscosity at the time of firing, and the dielectric layer and partition walls after firing. It is not preferable because air bubbles are present inside.
On the other hand, if the content exceeds 8%, crystals are precipitated in the glass. The content of ZrO ₂ in the bismuth-based lead-free glass is preferably 2 to 5% in that it is possible to prevent the precipitation of crystals while suppressing the formation of such bubbles.

Al ₂ O ₃ is an optional component for obtaining the bismuth-based lead-free powder glass of the present invention, and has the effect of expanding the vitrification range to stabilize the glass and improving the chemical durability.
The reason why the content of Al ₂ O ₃ is 0 to 5% by mass is that if it exceeds 5%, not only the bismuth-based lead-free glass after calcination is easily crystallized. This is because the softening point of bismuth-based lead-free glass is increased, and it may be difficult to fire bismuth-based lead-free powdered glass on a glass plate using high strain point glass or the like.
Al ₂ O ₃ content in that it can provide stability and chemical durability as glass while making bismuth-based lead-free powder glass bakable on a glass plate using high strain point glass or the like The amount is preferably 2-5%.

ZnO is also an optional component for obtaining the bismuth-based lead-free powder glass of the present invention, and when contained, exhibits the effect of lowering the softening point of the bismuth-based lead-free powder glass. The reason why the content of ZnO is 0 to 30% by mass is that the bismuth-based lead-free glass obtained when the content exceeds 30% may cause crystallization during firing. .
In terms of reliably preventing this crystallization, the content of ZnO is preferably 0 to 25%.

TiO _{2 is} also an optional component for obtaining the bismuth-based lead-free powder glass of the present invention, and the thermal expansion coefficient of the bismuth-based lead-free glass can be adjusted by adjusting the content. By being contained in, it has the effect of improving the chemical durability of the bismuth-based lead-free glass.
The content of TiO ₂ is 0% to 5% by mass. When the content of TiO ₂ exceeds 5%, the softening point of the bismuth-based lead-free glass increases, and the bismuth-based lead-free powder glass. This is because it may be difficult to fire the glass on a glass plate using high strain point glass or the like.

  CaO, MgO, SrO, and BaO are also optional components for the bismuth-based lead-free glass of the present embodiment, and the thermal expansion coefficient of the bismuth-based lead-free glass can be adjusted by adjusting the content. It has the effect of stabilizing. The content is set to 0 to 15%. When the content exceeds 15%, the softening point of the bismuth-based lead-free glass is increased, and the bismuth-based lead-free powder glass is changed to a high strain point glass or the like. This is because it may be difficult to fire on the used glass plate.

  Moreover, as a bismuth-type lead-free glass, it is preferable to adjust the difference between the softening point and the glass transition point to be 60 to 80K using the above components in the above content. . By setting the difference between the softening point and the glass transition point of the bismuth-based lead-free glass to 60 to 80K, the viscosity of the bismuth-based lead-free glass at the time of firing is reduced without hindering the defoaming behavior. It can suppress more reliably that a bubble remains in a dielectric material layer or a partition.

The softening point and glass transition point can usually be measured using a differential thermal analyzer (DTA). For example, a differential type differential thermal balance (trade name “TG-DTA” manufactured by Rigaku Corporation). TG8120 ”), about 50 mg of bismuth-based lead-free powder glass sample and a reference of about the same weight of alumina powder are placed in a platinum cell, and the temperature is increased from room temperature at a rate of 20 ° C./min. It can obtain | require from the DTA curve obtained.
For example, the endothermic start temperature at the endothermic peak can be obtained by extrapolation by the tangent method and used as the glass transition point, and the endothermic end temperature at the endothermic peak can be obtained by extrapolation by the tangential method and obtained as the softening point.

The bismuth-based lead-free glass preferably has a thermal expansion coefficient of 60 to 85 × 10 ⁻⁷ / ° C., and the thermal expansion coefficient can be measured using a thermomechanical analyzer (TMA), For example, a rod-shaped sample having a diameter of about 5 mm × length of 10 to 20 mm using bismuth-based lead-free glass and a standard sample formed of quartz glass are used as a thermomechanical analyzer (trade name “TMA8310” manufactured by Rigaku Corporation). )), It can be obtained from the thermal expansion curve obtained by raising the temperature from room temperature at 10 ° C./min.
For example, the coefficient of thermal expansion observed from 50 ° C. to 350 ° C. can be averaged to obtain the coefficient of thermal expansion of the bismuth lead-free glass.

  Next, a method for producing a bismuth-based lead-free powder glass will be described. The bismuth-based lead-free glass produced with the above components is made into a powder form in which the volume-based cumulative particle size distribution curve has a 50% value of less than 2.0 μm. For example, all the raw materials are blended so that the components as described above have the content as described above, and are mixed and melted at a temperature of, for example, 1000 to 1100 ° C. to produce a uniform glass. It can be carried out by classifying glass after it is made into powder by a grinding means such as a ball mill.

As the classifying means, generally used classification means such as sieving and airflow classification can be employed.
At this time, the 50% value of the volume-based cumulative particle size distribution curve is set to less than 2.0 μm, and further, the 90% value is classified so as to be less than 5.0 μm, whereby the dielectric layer and the partition wall of the PDP after firing are classified. It can suppress more reliably that a bubble remains.
In addition, it is more preferable that the 50% value of the volume-based cumulative particle size distribution curve is less than 1.0 μm in that the remaining of bubbles after firing can be more reliably suppressed.

Further, when the bismuth-based lead-free powder glass of this embodiment is used as a dielectric layer forming material or a partition forming material such as a glass paste or a green sheet for forming a dielectric layer or a partition, it is usually a bismuth-based A resin material is used as a vehicle together with lead-free powdered glass. Also, the dielectric layer forming material (back dielectric layer forming material) on the back side of the dielectric layer forming material and the partition wall forming material are blended with fillers in addition to bismuth-based lead-free powder glass and resin material. .
By including a filler in the back dielectric layer forming material or the partition wall forming material, the mechanical strength of the sintered back dielectric layer and partition walls can be improved, and the color can be adjusted.

As the resin material and filler used for the back surface dielectric layer forming material and partition wall forming material, those used for general dielectric layer forming materials and partition wall forming materials such as glass paste and green sheet can be used. .
However, for this filler, it is preferable to use at least one of Al ₂ O ₃ , TiO ₂ , ZnO, SiO ₂ , ZrO ₂ , and MgO, and this filler and the bismuth type as described above are used. It is preferable that the proportion of the filler in the total amount with the lead-free powdered glass is 40% or less by mass and is blended in the back dielectric layer forming material and the partition wall forming material.

  In addition, it is possible to adopt a generally used method for manufacturing a dielectric layer forming material such as a glass paste or a green sheet or a partition wall forming material, such as a method of kneading a bismuth-based lead-free powder glass, a resin material and a filler. it can.

  EXAMPLES Next, although an Example is given and this invention is demonstrated in more detail, this invention is not limited to these.

(Examples 1-11, Comparative Examples 1-5):
The raw materials were prepared so as to have the composition shown in Table 1 and Table 2, and after mixing, they were melted at a temperature of 1000 to 1200 ° C. for 1 to 2 hours. The molten glass was quenched with a stainless steel cooling roll to produce glass flakes.
Next, after the glass flakes were pulverized, airflow classification was performed so that the 50% value (D50 value) and 90% value (D90 value) of the volume-based cumulative particle size distribution curve were as shown in Tables 1 and 2. Bismuth-based lead-free powder glass of each example and comparative example was produced.

  The 50% value (D50 value) and 90% value (D90 value) of the volume-based cumulative particle size distribution curve of this bismuth-based lead-free powdered glass are obtained by dispersing about 100 mg of bismuth-based lead-free powdered glass in water and then Nikkiso Co., Ltd. This was confirmed by measuring a volume-based cumulative particle size distribution curve using a company-made laser diffraction / scattering particle size analyzer (trade name “MICROTRAC HRA MODEL: 9320-X100”).

(Evaluation)
1) Thermal expansion coefficient A rod-shaped sample having a diameter of about 5 mm and a length of 10 to 20 mm was prepared using the bismuth-based lead-free powder glass of each Example and Comparative Example, and a standard sample formed by the rod-shaped sample and quartz glass Using a thermomechanical analyzer (trade name “TMA8310”) manufactured by Rigaku Denki Co., Ltd., the temperature is measured at a rate of 10 ° C./min from room temperature to measure the thermal expansion curve, and from 50 ° C. to 350 ° C. The values of the observed thermal expansion coefficients were averaged to obtain the thermal expansion coefficients of the bismuth-based lead-free powder glasses of the examples and comparative examples. The results are shown in Tables 1 and 2.

2) Glass transition point and softening point About 50 mg of lead-free powder glass of each example and comparative example was sampled in a platinum cell, and approximately the same amount of alumina powder was sampled in the same platinum cell as a reference. A DTA curve was collected by raising the temperature from room temperature at a rate of temperature increase of 20 ° C./min using a company-made differential type differential thermal balance (trade name “TG-DTA TG8120”). The obtained endothermic start temperature at the endothermic peak of the DTA curve was extrapolated by the tangent method to obtain the glass transition point, and the endothermic end temperature at the endothermic peak was extrapolated by the tangential method to obtain the softening point. The results are shown in Tables 1 and 2.

3) Apparent porosity The bismuth-based lead-free powder glass of each example and comparative example and Al ₂ O ₃ powder (average particle size: 1.5 μm) were mixed in a mass ratio of 8: 2, and press-molded. It was formed into a pellet shape having a diameter of 30 mm and a thickness of 5 mm using a machine. This pellet was fired at 570 ° C. for 30 minutes in an electric firing furnace to produce an apparent porosity measurement sample.
The apparent porosity of this produced sample was measured based on JIS C 2141.
The results are shown in Table 3.

4) Dielectric breakdown voltage / discoloration The bismuth-based lead-free powder glass of each Example and Comparative Example and a vehicle mainly composed of ethylcellulose were mixed and kneaded to prepare a glass paste.
On the electrode (silver electrode) formed by printing and firing a silver conductor in a predetermined pattern on a high strain point glass plate, the glass paste obtained as described above is 20 μm thick after firing. By screen printing and baking, a glass film made of the bismuth-based lead-free powder glass of each example and comparative example was formed on the silver electrode.
At this time, the firing temperature was 570 ° C., and the firing time was 30 minutes.
An electrode was further provided on the glass film, and the dielectric breakdown voltage with the silver electrode was measured based on JIS C2110.
The results are shown in Table 3.
Moreover, it was observed visually whether the discoloration by reaction with a silver electrode has generate | occur | produced in the glass film formed on the silver electrode. The results are shown in Table 3.

As described above, the glass film fired using the bismuth-based lead-free powder glass of the present invention is superior in the dielectric breakdown voltage, and the bismuth-based lead-free powder glass of the present invention is mixed with the filler and fired. The apparent porosity is also reduced.
That is, from Table 3, according to the present invention, firing is possible on a glass plate using high strain point glass or the like as required in the formation of dielectric layers or partition walls of flat display panels such as PDP. However, it can be seen that a bismuth-based lead-free powder glass in which the formation of bubbles during firing is suppressed can be provided.

Claims (6)

Bismuth-based lead-free glass is formed into a powder form, and is a bismuth-based lead-free powder glass used for forming a dielectric layer or partition of a flat display panel,
Bi ₂ O ₃ : 30 to 75%, SiO ₂ : 1 to 15%, B ₂ O ₃ : 5 to 20%, ZrO ₂ : 2 to 8%, Al ₂ O ₃ : 0 to 0% by mass in terms of oxide Bismuth-based lead-free glass containing 5%, ZnO: 0 to 30%, TiO ₂ : 0 to 5%, and one or more of CaO, MgO, SrO, BaO in a total of 0 to 15% is used. In addition, a bismuth-based lead-free powder glass characterized in that the 50% value of the volume-based cumulative particle size distribution curve is formed in a powder form that is less than 2.0 μm. In terms of mass% in terms of oxide, the content of Bi ₂ O ₃ is 30 to 50%, the content of SiO ₂ is 1 to 10%, the content of B ₂ O ₃ is 10 to 20%, and The bismuth-based lead-free powder glass according to claim 1, wherein the ZnO content is 0 to 25%. The bismuth-based lead-free powder glass according to claim 1 or 2, wherein a 90% value of the volume-based cumulative particle size distribution curve is less than 5.0 µm. The bismuth lead-free powder glass according to any one of claims 1 to 3, wherein a temperature difference between a softening point and a glass transition point of the bismuth lead-free glass is 60 to 80K. A back dielectric layer forming material used for forming a back dielectric layer of a flat display panel, comprising a bismuth-based lead-free powder glass and a filler,
The bismuth lead-free glass according to any one of claims 1 to 4 is used for the bismuth lead-free powder glass, and the filler is any one of Al ₂ O ₃ , TiO ₂ , ZnO, SiO ₂ , ZrO ₂ , and MgO. 1 or more types are used, and the ratio of the filler to the total amount of the bismuth-based lead-free powder glass and the filler is 1 to 40% by mass, forming a back dielectric layer Wood. A bismuth-based lead-free powder glass and a filler, and a partition wall forming material used for forming a partition wall of a flat display panel,
The bismuth lead-free glass according to any one of claims 1 to 4 is used for the bismuth lead-free powder glass, and the filler is any one of Al ₂ O ₃ , TiO ₂ , ZnO, SiO ₂ , ZrO ₂ , and MgO. 1 or more types are used, The ratio of the said filler to the total amount of the said bismuth-type lead-free powder glass and the said filler shall be 1-40% by mass, The partition wall forming material characterized by the above-mentioned.