JP2006111463A - Plasma display panel sealing powder and plasma display panel sealing paste using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plasma display panel (PDP) sealing powder having thermal expansion coefficient matched to that of a glass substrate and excellent fluidity to air-tightly seal, and PDP sealing paste using the same. <P>SOLUTION: The PDP sealing powder comprises SnO-P<SB>2</SB>O<SB>5</SB>-based glass powder and filler powder. As the filler powder, KZr<SB>2</SB>(PO<SB>4</SB>)<SB>3</SB>is used. The PDP sealing paste is prepared by kneading the PDP sealing powder comprising the SnO-P<SB>2</SB>O<SB>5</SB>-based glass powder and using KZr<SB>2</SB>(PO<SB>4</SB>)<SB>3</SB>as the filler powder with vehicle. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a powder used for sealing a front panel and a rear panel or a rear panel and an exhaust pipe of a plasma display (PDP) and a PDP sealing paste using the powder.

  In recent years, development of flat panel displays (FPDs) such as liquid crystal displays (LCDs) and PDPs has been rapidly progressing as large flat TVs and wall-mounted TVs.

  In the PDP, minute cells are regularly formed in the vertical and horizontal directions between the front plate and the back plate, and when discharging inside the cell, ultraviolet light is radiated from a rare gas enclosed in the cell, and a phosphor that absorbs the ultraviolet light is formed. Characters and images are displayed by emitting visible light fluorescence.

  Therefore, in the manufacturing process of the PDP, a step of sealing a predetermined amount of rare gas inside the panel (between the front plate and the back plate) is essential.

  In order to seal the gas, the front plate and the back plate are hermetically sealed over the entire periphery of the non-display portion by adding a vehicle to a mixture of low melting glass powder and filler powder (sealing powder) and kneading the paste. .

  Also, in order to exhaust the gas inside the panel or inject a rare gas inside the panel, a hole with a diameter of several mm is provided in the non-display portion of the back plate, an exhaust pipe is provided so as to cover the hole, and the back Air-sealing the base plate and exhaust pipe using a paste prepared by adding a vehicle to a mixture of low-melting glass powder and filler powder (sealing powder), or using a tablet with resin added to the sealing powder and molded into a ring shape To wear.

Until now, lead glass has been used as the low melting point glass powder, but SnO—P ₂ O ₅ based low melting point glass containing no lead has been developed due to environmental problems due to toxicity of lead (for example, Patent Documents 1 and 2).
JP 2001-19472 A JP 2002-293573 A

Conventionally, as a glass substrate for PDP, soda-lime glass (thermal expansion coefficient: 80 to 90 × 10 ⁻⁷ / ° C.) and high strain point glass developed as a glass substrate for PDP (thermal expansion coefficient: 80 to 85 × 10 ⁻⁷ / ° C.) is used. In order to produce a PDP, a heat treatment step such as sealing glass substrates is necessary, but a thermal shock is easily applied to the substrate by heating and cooling before and after the heat treatment step. Therefore, in order to reduce thermal shock, a glass substrate having a thermal expansion coefficient of 60 to 80 × 10 ⁻⁷ / ° C. has been developed.

Since the thermal expansion coefficient of SnO—P ₂ O ₅ based low melting point glass is as large as about 100 × 10 ⁻⁷ / ° C., filler powder with a small thermal expansion coefficient is mixed to correspond to the thermal expansion coefficient of a conventional glass substrate. The sealing material was adjusted to do. If the difference in thermal expansion coefficient between the sealing material and the glass substrate is large, cracks may occur at the sealing portion.

  However, when the content of the filler powder is increased in order to cope with a glass substrate having a small thermal expansion coefficient, the fluidity of the sealing material is lowered and it is difficult to hermetically seal.

  An object of the present invention is to provide a PDP sealing powder which has a thermal expansion coefficient matching with a glass substrate and has excellent fluidity and can be hermetically sealed, and a PDP sealing paste using the same.

The inventors of the present invention have the reason that the fluidity of the sealing material is lowered because SnO—P ₂ O ₅ -based low melting point glass powder reacts with the filler powder during sealing and devitrification is likely to occur. I found out.

Further, it is found that when KZr ₂ (PO ₄ ) ₃ is used as a filler powder, the reaction with the glass powder can be suppressed, and sufficient fluidity for sealing can be secured, and is proposed as the present invention.

The PDP sealing powder of the present invention comprises SnO—P ₂ O ₅ glass powder and filler powder, and is characterized in that KZr ₂ (PO ₄ ) ₃ is used as the filler powder.

The PDP sealing paste of the present invention is composed of SnO—P ₂ O ₅ glass powder and filler powder, and KDPr sealing powder and vehicle using KZr ₂ (PO ₄ ) ₃ as filler powder are kneaded. It is characterized by becoming.

The PDP sealing powder of the present invention is used as a sealing material in the form of a paste or a tablet, but since it is difficult to react between the SnO-P ₂ O ₅ glass powder and the filler powder, Sufficient fluidity can be obtained. Therefore, it can be hermetically sealed.

Moreover, even if the powder for PDP sealing of this invention seals a glass substrate with a thermal expansion coefficient of 60-80 * 10 < ^-7 > / (degreeC), a crack does not generate | occur | produce in a sealing part.

The PDP sealing powder of the present invention has a thermal expansion coefficient of 50 to 75 × 10 ⁻⁷ / ° C., even if a glass substrate having a thermal expansion coefficient of 60 to 80 × 10 ⁻⁷ / ° C. is sealed. This is preferable because no crack is generated in the portion and the glass substrate is hardly warped. A preferable thermal expansion coefficient is 50 to 72 × 10 ⁻⁷ / ° C., and more preferably 55 to 70 × 10 ⁻⁷ / ° C.

The PDP sealing powder of the present invention has a volume percentage display of SnO—P ₂ O ₅ glass powder of 55 to 85% and KZr ₂ (PO ₄ ) ₃ (hereinafter referred to as KZP) of 15 to 45%. In addition, it is preferable because sufficient fluidity for sealing can be obtained and the above thermal expansion coefficient can be obtained.

  In addition, among filler powders, filler powders other than KZP can be added up to 15% by volume of the PDP sealing powder. As filler powders other than KZP, cordierite, tin dioxide, β-eucryptite, mullite, silica, β-quartz solid solution, aluminum titanate, zircon, willemite, niobium pentoxide, etc. can be used alone or Used as a mixture.

The PDP sealing powder of the present invention preferably has an SnO—P ₂ O ₅ glass powder having an average particle size of 2 to 50 μm because the glass is easily melted at a low temperature.

  The PDP sealing powder of the present invention is preferably 4 to 60 μm in average particle size of the filler powder because the fluidity of the glass is hardly inhibited. If the average particle size of the filler powder is smaller than 4 μm, the surface area of the filler powder increases, so that it tends to react with glass during sealing. For this reason, the fluidity of the sealing material is likely to decrease, and it becomes difficult to hermetically seal. On the other hand, when it is larger than 60 μm, the mechanical strength after sealing of the sealing material tends to be low, and there is a possibility of leakage at the sealing portion.

Further, PDP sealing powder of the present invention, the composition of the SnO-P ₂ O ₅ based glass powder _{mol%, SnO 35~60%, P 2 O} 5 18~45%, B 2 O 3 0~30 %, ZnO 0-20%, SiO ₂ 0-15%, Al ₂ O ₃ 0-10%, R ₂ O 0-10% (R is Li, Na, K and Cs).

  The reason for limiting to the above composition range is shown below.

  SnO is a component that lowers the melting point of glass. If the SnO content is less than 35%, the viscosity of the glass increases and the sealing temperature tends to increase, and if it exceeds 60%, vitrification becomes difficult. In addition, since it will become easy to devitrify at the time of sealing when there is much SnO, it is preferable that it is 55% or less. Moreover, if it is 40% or more, since it is excellent in fluidity | liquidity and high airtightness is obtained, it is preferable.

P ₂ O ₅ is a glass forming oxide. If the P ₂ O ₅ content is less than 18%, it is difficult to obtain sufficient glass stability. If it is in the range of 18 to 45%, sufficient stability can be obtained for the glass, but if it exceeds 45%, the moisture resistance tends to deteriorate. Further, if P ₂ O ₅ is 20% or more, the glass is further stabilized, but if it exceeds 35%, the weather resistance of the sealing glass tends to be slightly deteriorated, so it is 20 to 35%. Is more preferable.

  ZnO is an intermediate oxide. ZnO is not an essential component, but is desirably 4% or more because it has a great effect of stabilizing the glass. However, if ZnO exceeds 20%, devitrification tends to occur on the glass surface during sealing. The ZnO content is desirably 5 to 15%.

SiO ₂ is a glass forming oxide. Although SiO ₂ is not an essential component, it is desirable to contain it because it has an effect of suppressing devitrification. If it exceeds 15%, the softening temperature rises and the sealing temperature tends to be high.

Al ₂ O ₃ is an intermediate oxide. Al ₂ O ₃ is not an essential component, but it is desirable to contain Al ₂ O _{3 because} it has the effect of stabilizing the glass and the effect of reducing the thermal expansion coefficient. However, if it exceeds 10%, the softening temperature rises and the sealing temperature tends to increase. In addition, when the stability of glass, a thermal expansion coefficient, fluidity | liquidity, etc. are considered, the range of 0.5 to 5% is more preferable.

R ₂ O (R is Li, Na, K and Cs) is not an essential component, but there is a tendency that the adhesive force is improved by adding at least one of the R ₂ O components in the composition. However, if the total amount exceeds 10%, devitrification tends to occur during sealing. Of R ₂ O, Li ₂ O is most likely to improve the adhesive strength.

  In addition to the above, the following components may be contained.

B ₂ O ₃ is a glass forming oxide. B ₂ O ₃ is not an essential component but has an effect of stabilizing the glass. However, if it exceeds 30%, the viscosity of the glass becomes too high, the fluidity at the time of sealing is remarkably deteriorated, and the airtightness of the sealing part tends to be impaired. A preferable range of B ₂ O ₃ is 0 to 25%. Since B ₂ O ₃ has a strong tendency to increase the viscosity of glass, it is required to have very high fluidity, and when it is necessary to significantly lower the softening point, B ₂ O ₃ should not be contained.

Although lanthanoid oxides such as La ₂ O ₃ and CeO ₂ are not essential components, the weather resistance of the glass tends to be improved by containing a total amount of 0.1% or more in the glass component.

In addition to the lanthanoid oxide, the use of other rare earths such as Y ₂ O ₃ is effective for improving the weather resistance of the glass. The amount of rare earth added excluding the lanthanoid oxide is preferably 0 to 5%.

  R′O (R ′ is Mg, Ca, Sr, and Ba) is not an essential component, but is useful as a component that stabilizes the glass. When the total amount of R′O exceeds 15%, devitrification tends to occur. Therefore, the content of R′O is desirably 15% or less, more preferably 10% or less.

In addition, for example, components that stabilize the glass, such as Nb ₂ O ₅ , TiO ₂ , ZrO ₂ , CuO, MnO, In ₂ O _3, can be contained in a total amount of up to 20%. In addition, when content of these stabilization components exceeds 20%, glass will become unstable and it will become difficult to manufacture. In order to obtain a more stable glass, the content is preferably 15% or less.

The contents of Nb ₂ O ₅ , TiO ₂ , and ZrO ₂ are all 0 to 15%, particularly preferably 0 to 10%. If the content of any component exceeds 15%, the glass tends to be unstable.

  The contents of CuO and MnO are both 0 to 10%, particularly preferably 0 to 5%. If the content of any component exceeds 10%, the glass tends to be unstable.

In ₂ O ₃ can be used for the purpose of obtaining high weather resistance. The content of In ₂ O ₃ is preferably 0 to 5%.

  Since PbO is an environmental load substance, it is preferable not to contain PbO substantially. In the present specification, “substantially not containing a certain substance” means that the content is 0.1% or less.

  Further, it is preferable that halogens such as F and Cl are not substantially contained since there is a risk of lowering the display luminance.

  Below, the preparation methods of the PDP sealing paste are demonstrated.

First, SnO—P ₂ O ₅ -based glass powder and filler powder having the above-described composition and average particle diameter are prepared.

Then, by volume percentage, SnO-P ₂ O ₅ based glass powder is 55 to 85 percent of mixed such filler powder is 15 to 45%, to produce a sealing powder.

  Subsequently, 20 to 80 parts by mass of a vehicle is added to 100 parts by mass of the sealing powder, and after stirring so that the sealing powder is uniformly dispersed, the powder aggregates and bubbles are removed using a roll mill to remove PDP. A sealing paste is prepared.

  The viscosity of the PDP sealing paste is preferably 200 to 1500 poise. If it is smaller than 200 poise, the glass powder or filler powder constituting the paste tends to settle, and if it is larger than 1500 poise, it tends to be difficult to uniformly apply to the glass substrate.

  The vehicle is obtained by uniformly mixing a binder resin and a solvent.

  The binder resin is a component that adjusts the viscosity of the vehicle. As the binder resin, polyethylene glycol derivatives (PEGD), nitrocellulose (NCE), polymethylstyrene (PMS), polyethylene carbonate (PEC), and the like can be used.

  The solvent is a component for diluting the sealing material in the form of paste. Examples of the solvent include N, N′-dimethylformamide (DMF), γ-butyrolactone (γ-BL), tetralin, butyl carbitol acetate (BCA), acetic acid. Ethyl, isoamyl acetate (IAA), dimethyl sulfoxide (DMSO), propylene carbonate (PRC), 2,4-diethyl-1,5-pentanediol, N-methyl-2-pyrrolidone, diethylene glycol monoethyl ether, diethylene glycol monoethyl ether Acetate, benzyl alcohol, toluene, 3-methoxy-3-methylbutanol, water, triethylene glycol monomethyl ether, triethylene glycol dimethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol It is possible to use allyl monobutyl ether, tripropylene glycol monomethyl ether, tripropylene glycol monobutyl ether, or the like. A highly viscous solvent can be used alone as a vehicle.

  When the vehicle is less than 20 parts by mass, it does not become a paste and tends to be difficult to handle. On the other hand, when the amount is more than 80 parts by mass, the vehicle component is burned or volatilized at the time of sealing, so that microbubbles are likely to be contained in the sealed part and the sealed part tends to leak.

  Next, a method for producing a PDP sealing tablet will be described.

First, SnO—P ₂ O ₅ -based glass powder and filler powder having the above-described composition and average particle diameter are prepared.

Then, by volume percentage, SnO-P ₂ O ₅ based glass powder 60 to 80% of mixed such filler powder is 20 to 40%, to produce a sealing powder.

  Subsequently, 0.1 to 25 parts by mass of a resin binder is added to 100 parts by mass of the sealing powder, and the mixture is uniformly stirred and granulated.

  Further, after filling the mold with a granular sealing material, a tablet precursor formed into a ring shape by press molding is prepared.

  Finally, the tablet precursor is baked at 350 to 430 ° C. for 5 to 30 minutes to produce a PDP sealing tablet.

  As the resin binder, polyethylene carbonate, polyethylene glycol derivatives, polymethylstyrene, nitrocellulose and the like can be used. In particular, a low-temperature decomposable resin binder is preferable because an organic component hardly remains in the glass and does not adversely affect the glass.

  When the amount of the resin is less than 0.1 parts by mass, it is not preferable because it is fragile and easily broken even when a tablet precursor is produced. On the other hand, when the amount is more than 25 parts by mass, the resin is easily carbonized during firing, which tends to inhibit hermetic adhesion, which is not preferable.

  When the baking temperature of the tablet precursor is lower than 350 ° C., the PDP sealing tablet is fragile and easily collapses. On the other hand, when the temperature is higher than 430 ° C., the tablet precursor may be softened and deformed.

  Hereinafter, the present invention will be described in detail based on examples.

  Table 1 shows the glass samples and Table 2 shows the sealing powder. Table 3 shows paste samples.

  The glass samples shown in Table 1 were produced as follows.

  First, glass raw materials were prepared so as to have the composition shown in the table, put into a quartz crucible, and melted at the temperature shown in the table for 2 hours with the quartz crucible covered.

  Subsequently, the molten glass was formed into a thin plate through two water-cooled rollers positioned in parallel, and pulverized using a ball mill to prepare a glass sample.

  The glass transition point was determined by differential thermal analysis (DTA).

  The softening point was determined from the temperature at the bottom of the second absorption peak of DTA.

  The thermal expansion coefficient was determined by a push rod type thermal expansion measuring device.

  The average particle diameter was measured using a laser diffraction type particle size distribution measuring apparatus (SALD2000 manufactured by Shimadzu Corporation).

  Moreover, KZP was used as a filler powder. This KZP was produced as follows.

First, 265.2 g of zirconium phosphate: ZrP ₂ O ₇ equivalent to 1 mol, 123.2 g of zirconium oxide: ZrO ₂ equivalent to 1 mol, and 118.1 g of potassium phosphate: KPO ₃ equivalent to 1 mol as raw materials were mixed, As a crystallization aid, 15.1 g of magnesium oxide corresponding to 3 wt% of the total amount was added and mixed with an alumina ball mill for 1 hour.

  Next, this mixed powder was fired at 1400 ° C. for 15 hours in an alumina crucible to synthesize KZP.

  After cooling, the sintered product of KZP was taken out from the crucible, pulverized and classified with an alumina ball mill, passed through a metal 325 mesh sieve, and a filler powder made of KZP having an average particle size of 15 μm was produced.

  The sealing powder shown in Table 2 was prepared by mixing the glass sample prepared in Table 1 and the filler powder using KZP at a ratio shown in the table.

  The fluidity was evaluated as follows.

  First, a mass corresponding to the density of the obtained sealing powder was put into a mold and press-molded to prepare a cylindrical button having an outer diameter of 20 mm.

  Next, the button was placed on the window glass, heated to the firing temperature described in the table in the air at a rate of 10 ° C./min and held for 10 minutes, and then the button diameter was measured. .

  The paste samples shown in Table 3 were produced as follows.

  First, a glass sample, a sealing powder composed of a filler powder and a vehicle were mixed and stirred so as to have a mixing ratio in the table to prepare a pre-kneaded paste. In addition, the vehicle used what mixed resin and a solvent of a table | surface in the ratio in the table | surface in the table | surface uniformly.

  Next, a paste sample from which aggregates and bubbles were removed from the pre-kneaded paste using a roll mill was prepared.

  Next, each obtained glass paste was apply | coated to the uniform thickness by the screen-printing method on the soda glass plate.

  Finally, in order to volatilize the solvent, drying was performed at 150 ° C. for 10 minutes, and then the glass paste was heated to the firing temperature in air and held for 10 minutes to perform firing. Using the sample thus prepared, the leveling property and firing state of the paste were examined.

  As for the leveling property of the paste, the surface of the paste after application was observed, and “◯” if smooth and glossy, and “x” otherwise.

  In addition, the firing state was “◯” for smooth and glossy, and “x” for other cases.

As is clear from Table 2, Samples A to F had a thermal expansion coefficient of 55.0 to 72.9 × 10 ⁻⁷ / ° C. and a fluidity of 21 to 23 mm and a good fluidity.

  Further, as apparent from Table 3, Samples 1 to 6 were good in both leveling properties and fired state.

Claims (7)

A PDP sealing powder comprising a SnO—P ₂ O ₅ glass powder and a filler powder, wherein KZr ₂ (PO ₄ ) ₃ is used as the filler powder. _2. The PDP sealing powder according to claim 1, wherein the SnO—P ₂ O ₅ glass powder is 55 to 85% and KZr ₂ (PO ₄ ) ₃ is 15 to 45% by volume%. The powder for sealing PDP according to claim 1 or 2, wherein the SnO-P ₂ O ₅ glass powder has an average particle diameter of 2 to 50 µm.   4. The PDP sealing powder according to claim 1, wherein the filler powder has an average particle size of 4 to 60 [mu] m. The composition of SnO—P ₂ O ₅ glass powder is expressed in mol%, SnO 35-60%, P ₂ O ₅ 18-45%, ZnO 0-20%, B ₂ O ₃ 0-30%, SiO ₂ 0 _{~15%, Al 2 O 3 0~10} %, R 2 O 0~10% (R is Li, Na, K and Cs) according to any one of claims 1 to 4, characterized in that it contains PDP sealing powder.   A PDP sealing paste obtained by kneading the PDP sealing powder according to claim 1 and a vehicle.   The PDP sealing paste according to claim 6, wherein 20 to 80 parts by mass of a vehicle is added to 100 parts by mass of the PDP sealing powder.