JP2000053443A - Lead-free glass composition and composition for forming plasma display panel partition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a stable composition having the same properties as a lead glass and specified in the softening point by mixing substantially ZnO, Al2O3, P2O5 and the like in a specific ratio. SOLUTION: 25-55% ZnO, 1-15% Al2O3, 30-55% P2O5, 0-15% SiO2 and 0-20% BaO+CaO+MgO+SrO by mol. are mixed. The softening point of the resultant composition is 460-590 deg.C. The average linear expansion coefficient at 3-300 deg.C is preferably 50×10-7 to 95×10-7/ deg.C. A paste prepared by mixing preferably this composition with an inorganic filler and/or an inorganic pigment and further mixing a binder and a solvent therewith is applied on a rear glass substrate by printing or the like, fired and pattered to obtain a plasma display panel partition. The total quantity of the inorganic filler and/or the inorganic pigment is preferably 5-200 pts.wt. per 100 pts.wt. lead-free glass composition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lead-free glass composition and a PDP particularly suitable for forming barrier ribs on a back glass substrate of a plasma display panel (hereinafter referred to as "PDP").
The present invention relates to a composition for forming a partition.

[0002]

2. Description of the Related Art A large and thin PDP has been developed as a display replacing a conventional cathode ray tube.
FIG. 1 is a schematic configuration diagram of a PDP. In the PDP, stripe-shaped electrodes orthogonal to each other are arranged on the inner surfaces of two glass substrates, that is, a front glass substrate 1 and a rear glass substrate 2. The front glass substrate 1 has display electrodes 3 and bus electrodes 4, the rear glass substrate 2 has address electrodes 8,
Each is arranged.

Each electrode is covered with a dielectric film 5. The dielectric film 5 of the front glass substrate 1 is covered with a protective film 6. Partitions 7 having a height of about 100 μm are arranged on the rear glass substrate 2 in the same direction (vertical direction) as the address electrodes 8, and a layer of a phosphor 9 is formed between the partitions 7. After the periphery of the front glass substrate 1 and the rear glass substrate 2 is hermetically sealed with a sealing material (not shown), a gas such as a Ne—Xe mixed gas is filled.

[0004] Various methods have been proposed for forming the partition walls 7, but the mainstream in recent years is a method called a sand blast method. The sand blasting method is a method in which a glass paste, which is a composition for forming a partition having a predetermined thickness, is applied to the surface of a glass substrate, and after drying, a photosensitive dry film having blast resistance is laminated thereon, and then a predetermined partition shape is formed. After patterning by exposure and development, a portion without a photosensitive dry film is removed by spraying abrasive powder, followed by baking to form partition walls. By using this method, a partition having a high definition pattern can be formed.

[0005] The glass paste used in the sandblasting method is mainly composed of glass, and contains inorganic pigments, inorganic fillers,
Etc. Since the glass is fired on the glass substrate constituting the PDP by the above method, it is necessary to fire the glass at 600 ° C. or less in consideration of the heat resistance of the substrate glass such as soda lime silica glass conventionally used as the glass substrate. There is. For this reason, a glass having a relatively low melting point is used. The glass of the glass paste which is currently the mainstream is PbO—SiO ₂ containing 50% by weight or more of PbO.
It is a system glass.

As described above, the method of forming partition walls by a sand blast method using a glass paste containing a lead-containing low-melting glass as a main component is mainly used. However, in the sand blast method, unnecessary portions are cut off. As a result, a large amount of lead-containing waste is generated, which may cause environmental problems. Therefore, a lead-free glass paste for forming a PDP partition wall is required.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a lead-free glass composition containing no lead and a composition for forming a PDP partition wall, which may cause environmental problems.

[0008]

According to the present invention, there is substantially provided, in terms of mole% on an oxide basis, ZnO: 25 to 55%, Al ₂
O ₃ : 1 to 15%, P ₂ O ₅ : 30 to 55%, SiO
₂ : 0 to 15%, BaO + CaO + MgO + SrO: 0
A lead-free glass composition having a softening point of 460 to 590 ° C, and a PDP partition wall-forming composition containing the lead-free glass composition.

[0009] The present inventor has suggested that environmental problems arise.
ZnO, Al without it_Two O_Three , P _Two O_Five Oxides such as
As a result of intensive research focusing on
Found a stable lead-free glass composition with the characteristics of
Reached.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The lead-free glass composition of the present invention is a glass composition containing substantially no lead. ZnO is an essential component, and if it exceeds 55 mol%, it tends to crystallize, making it difficult to obtain stable glass. It is preferably at most 48 mol%. If it is less than 25 mol%, the softening point becomes too high, and it becomes difficult to fire at a predetermined temperature. It is preferably at least 30 mol%.

Al ₂ O ₃ is an essential component and has an effect of improving water resistance. If it exceeds 15 mol%, the softening point will be too high and it will be difficult to fire at a predetermined temperature. Preferably it is 9 mol% or less. If it is less than 1 mol%, the effect of improving the water resistance is lost. It is preferably at least 2 mol%.

P ₂ O ₅ is an essential component and the most important component for forming glass. If it exceeds 55 mol%, it tends to be crystallized, making it difficult to obtain stable glass. Preferably it is 50 mol% or less. If it is less than 30 mol%, the softening point becomes too high, and it becomes difficult to fire at a predetermined temperature. It is preferably at least 38 mol%.

Although SiO ₂ is not an essential component, it is effective for stabilizing the glass, and may be contained up to 15 mol%. 1
If it exceeds 5 mol%, the softening point becomes too high, and it becomes difficult to fire at a predetermined temperature. Preferably it is 10 mol% or less.

BaO, C which is an alkaline earth metal oxide
Although aO, MaO, and SrO are not essential components, they are mainly effective for adjusting the softening point and the coefficient of thermal expansion. Like general glass, ZnO-Al ₂ O _3-
There is a correlation between the softening point and the coefficient of thermal expansion even in the three-component glass system of P ₂ O ₅ , and the coefficient of thermal expansion decreases as the softening point increases. Therefore, when glasses having the same softening point and different thermal expansion coefficients are required, or when glasses having the same thermal expansion coefficient and different softening points are required, ZnO—Al ₂ O
This is extremely difficult to achieve with a _3- P ₂ O ₅ ternary glass system. However, by adjusting the content of these alkaline earth metal oxides, it is possible to produce glasses having the same softening point and different thermal expansion coefficients, or glasses having the same thermal expansion coefficient and different softening points.

The effect of increasing the coefficient of thermal expansion is as follows: BaO>
It becomes smaller in the order of SrO>CaO> MgO. The effect of increasing the softening point is as follows: MgO>CaO>SrO> Ba
It becomes smaller in the order of O. BaO, CaO, MaO, SrO
May contain up to 20 mol% of their total amount. 2
If it exceeds 0 mol%, it tends to crystallize, making it difficult to obtain stable glass. It is preferably at most 12 mol%.

In addition to the above components, a coloring component such as Fe ₂ O ₃ may be added up to 0.5 mol%. Further, other components may be added as long as the object of the present invention is not impaired, but the total amount is 5 mol% or less.

The softening point of the lead-free glass composition of the present invention is 46
0-590 ° C. When the temperature exceeds 590 ° C., the flow of the PDP partition wall forming composition is reduced when the PDP partition wall forming composition containing the lead-free glass composition of the present invention is fired at 600 ° C. or lower on a glass substrate in the PDP partition wall forming step. This makes it difficult to form a partition having a high-definition pattern, and also reduces the adhesion to a glass substrate.

If the softening point is lower than 460 ° C., a problem occurs in the hermetic sealing around the front glass substrate and the rear glass substrate performed at the end of the PDP manufacturing process. That is, in the hermetic sealing, heat treatment at about 450 ° C. is performed. However, when the softening point is lower than 460 ° C., the partition shape is deformed, the lower portion of the partition expands, the width between the partitions becomes narrower, and the height of the partition becomes lower. Problems such as the inability to obtain a predetermined width / height ratio occur.

In the lead-free glass composition of the present invention, "30 to 30"
The “average coefficient of linear expansion at 0 ° C.” (hereinafter referred to as the coefficient of thermal expansion) is preferably from 50 × 10 ^{−7 to} 95 × 10 ⁻⁷ / ° C. The reason is described below.

The rear glass substrate has a coefficient of thermal expansion of 70
Soda-lime silica-based glass having a temperature of ^{10-7 to} 85 ^10-7 / ° C is generally used. However, since the partition walls formed on the rear glass substrate are subjected to heat treatment several times in the PDP manufacturing process, the heat is It is desirable that the difference between the expansion coefficient and the thermal expansion coefficient of the rear glass substrate is small. The difference is preferably 10 × 10 ⁻⁷ / ° C. or less, and the coefficient of thermal expansion of
It is preferably from 0 × 10 ^{−7 to} 85 × 10 ⁻⁷ / ° C.

The composition for forming a PDP partition wall of the present invention preferably contains an inorganic filler or an inorganic pigment for adjusting the thermal expansion coefficient of the partition wall in addition to the lead-free glass composition of the present invention. The lead-free glass composition of the present invention has a coefficient of thermal expansion of 50 × 1
If it is 0 ^{-7 to} 95 × 10 ^-7 / ° C., the coefficient of thermal expansion of the partition wall is within the above-mentioned preferable range by adjusting the coefficient of thermal expansion.
X 10 ^{-7 to} 85 x 10 ^-7 / ° C.

When the coefficient of thermal expansion of the lead-free glass composition of the present invention exceeds 95 × 10 ⁻⁷ / ° C., the expansion coefficient of the partition walls becomes 85 × 1.
If the temperature exceeds 0 ^-7 / ° C, the partition walls may be cracked or peeled off. If it is less than 50 × 10 ⁻⁷ / ° C., the expansion coefficient of the partition wall becomes less than 60 × 10 ⁻⁷ / ° C., and there is a possibility that the rear glass substrate may be cracked or the rear glass substrate may be deformed.

The composition for forming a PDP partition wall of the present invention contains the lead-free glass composition of the present invention. The composition for forming a PDP partition wall of the present invention preferably contains an inorganic filler and / or an inorganic pigment in addition to the lead-free glass composition.

The inorganic filler is used not only for adjusting the coefficient of thermal expansion of the partition, but also for improving the strength of the partition, adjusting the shrinkage during firing, or adjusting the denseness of the partition. Alumina, zirconia, or the like is used to improve the strength of the partition. For adjusting the thermal expansion coefficient of the partition, zircon, cordierite, mullite, amorphous silica, alumina, forsterite, α-quartz, fluorite, or the like is used.

The inorganic pigment is used for adjusting the thermal expansion coefficient of the partition walls.
It is used for coloring the partition walls, adjusting the shrinkage during firing, or adjusting the denseness of the partition walls. In order to make the color tone of the partition walls white, titanium oxide, alumina, or the like is used. Cu-Cr, Cu-Cr-
Mn-based or the like is used.

When an inorganic filler or an inorganic pigment is excessively added for the purpose of adjusting the thermal expansion coefficient or the like, the flowability of the composition for forming a PDP partition wall is reduced upon firing at a predetermined temperature, so that a partition wall having a high definition pattern is formed. And the adhesion to the glass substrate may be reduced.

The total amount of the inorganic filler and the inorganic pigment is preferably 5 to 200 parts by weight based on 100 parts by weight of the lead-free glass composition. If the amount is less than 5 parts by weight, the shrinkage during firing may be too large. It is more preferably at least 10 parts by weight, particularly preferably at least 15 parts by weight. If the amount is more than 200 parts by weight, the denseness of the partition may be reduced. It is more preferably at most 100 parts by weight, particularly preferably at most 45 parts by weight.

The composition for forming a PDP partition wall of the present invention preferably contains a binder and an organic solvent. Powders such as lead-free glass, inorganic fillers, inorganic pigments, and the like are mixed with a binder and an organic solvent to form a glass paste, applied to a rear glass substrate by printing or the like, and then fired and patterned to form PDP partition walls.

The binder and the organic solvent are not particularly limited, and those conventionally used can be used. As the binder, for example, cellulosic materials such as methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, hydroxyethyl ethyl cellulose,
Polyvinyl butyral, polyvinyl acetate, polyvinyl alcohol, and the like are used. As an organic solvent,
For example, α-terpineol, butyl carbitol acetate, 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate, and the like are used.

The maximum particle diameter of the powder of lead-free glass, inorganic filler, inorganic pigment, etc. is preferably 2 to 20 μm. If it exceeds 20 μm, it may be difficult to densify the partition after firing and obtain a partition with a high definition pattern.
Preferably it is 15 μm or less. If it is less than 2 μm, the viscosity of the glass paste becomes too high and the workability may be impaired.

The composition for forming a PDP partition wall of the present invention is produced by a method similar to that of a conventional glass paste. That is, the raw materials are prepared, mixed and heated and melted so as to have a predetermined composition, and then poured into a mold to obtain a lead-free glass block. Next, it is pulverized by a pulverizer such as a ball mill to produce a lead-free glass powder. After blending and mixing an inorganic filler and an inorganic pigment with the lead-free glass powder so as to obtain desired properties, a binder and an organic solvent are added, and the mixture is kneaded with a three-roll mill or the like to obtain a glass paste.

[0032]

EXAMPLES Next, the present invention will be described specifically with reference to examples, but the present invention is not limited to the following examples. Each raw material is prepared so as to have a composition (unit: mol%) shown in Table 1,
It was put in a platinum crucible, heated and melted in an electric furnace at 1200 to 1400 ° C. for 2 hours, then rapidly cooled and formed into a plate to obtain a plate-shaped glass block. Next, the glass block is pulverized using a ball mill to have a maximum particle size of 2 to 2.
A glass powder of 20 μm was obtained. The glass transition point, softening point and thermal expansion coefficient of these glasses were measured, and the maximum particle size of the obtained glass powder was measured. The measurement method is described below, and the measurement results are shown in Table 1.

Glass transition point (° C.) and softening point (° C.):
Glass was used as a powder and measured using a differential thermal analyzer.
The heating rate was 10 ° C./min. Thermal expansion coefficient (× 10 ^-7 / ° C): 30 to
The average linear expansion coefficient at 300 ° C. was measured. The heating rate was 10 ° C./min. Maximum particle size (μm): Measured with a laser diffraction type particle size distribution analyzer.

In Table 1, Examples 1 to 7 are Examples and Examples 8 to
9 is a comparative example. In Examples 1 to 7, stable glasses were obtained. In contrast, Example 8 did not become glass, and Example 9 was vitrified, but had a high softening point and a large thermal expansion coefficient.

The glass powders of Examples 1 to 7 and Example 9 were added to Table 2
The inorganic filler and the inorganic pigment shown in Table 2 were mixed at the ratio shown in the column of content (unit:% by weight) in Table 2. Further, ethyl cellulose was added as a binder, and α-terpineol was added as a solvent. After stirring well, the mixture was kneaded using a ceramic three-roll mill to produce a glass paste having a viscosity of 15 × 10 ⁴ centipoise.

Next, a glass paste is printed by screen printing on a soda lime silica glass substrate having a coefficient of thermal expansion of 83 × 10 ⁻⁷ / ° C., dried at 125 ° C. for 10 minutes, and baked at 560 ° C. for 30 minutes. A fired body having a height of 100 μm was formed. The fired body formed on the glass substrate was observed with an optical microscope to check for cracks and peelings. The results are shown in the column of evaluation in Table 2.

The fired bodies obtained by combining the glasses of Examples 1 to 7, various inorganic fillers and various inorganic pigments have no cracks or peeling off, and are suitable as PDP partition walls. On the other hand, cracks and peeling were observed in the fired body using the glass of Example 9, which was not suitable as a PDP partition wall.

[0038]

[Table 1]

[0039]

[Table 2]

[0040]

The lead-free glass composition and PDP of the present invention
The partition wall forming composition does not contain a lead component, and there is no possibility of causing environmental problems. Moreover, cracks in the rear glass substrate or the partition walls, separation of the partition walls from the rear glass substrate, and PDP partition walls that are less likely to occur can be formed.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a PDP.

[Description of Signs] 1: Front glass substrate 2: Rear glass substrate 3: Display electrode 4: Pass electrode 5: Dielectric film 6: Protective film 7: Partition wall 8: Address electrode 9: Phosphor

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4G062 AA08 AA09 AA15 BB09 CC10 DA01 DA02 DA03 DA04 DB03 DB04 DC01 DD05 DD06 DE04 DE05 DE06 DF01 EA01 EA10 EB01 EC01 ED01 ED02 ED03 ED04 EE01 EE02 EE03 EE04 EF03 EF04 EF03 EG04 FA01 FA10 FB01 FC01 FD01 FE01 FF01 FG01 FH01 FJ01 FK01 FL01 GA01 GA10 GB01 GC01 GD01 GE01 HH01 HH03 HH05 HH07 HH09 HH11 HH13 HH15 HH17 HH20 JJ01 JJ03 JJ05 JJ07 PP03 KK10 KK03 KK10 KK10 KK10 KK PP14 PP16 5C027 AA09 5C040 GF18 KA09 KA10 KA17 KB03 KB19 KB28 KB29 MA23 5C094 AA33 AA36 AA60 BA31 BA32 CA19 EB02 EC04 FA01 FA02 FB02 GB10 JA01 JA20

Claims (6)

[Claims] 1. A substantially represented by mol% based on _{oxides, ZnO 25~55%, Al 2 O} 3 1~15%, P 2 O 5 30~55%, SiO 2 0~15%, BaO + CaO + MgO + SrO 0 A lead-free glass composition having a softening point of 460 to 590 ° C. 2. In terms of mol% on an oxide basis, ZnO 30 to 48%, Al ₂ O ₃ 2 to 9%, P ₂ O ₅ 38 to 50%, SiO ₂ 0 to 10%, BaO + CaO + MgO + SrO 0 The lead-free glass composition according to claim 1, comprising: 3. The lead-free glass composition according to claim 1, wherein the average linear expansion coefficient at 30 to 300 ° C. is 50 × 10 ^{−7 to} 95 × 10 ⁻⁷ / ° C. 4. A composition for forming a partition wall of a plasma display panel, comprising the lead-free glass composition according to claim 1, 2 or 3. 5. The composition for forming a partition wall of a plasma display panel according to claim 4, comprising an inorganic filler and / or an inorganic pigment. 6. The composition for forming a partition wall of a plasma display panel according to claim 4, which comprises a binder and an organic solvent.