JP5018032B2 - Lead-free glass for electrode coating - Google Patents

Description

  The present invention is a lead-free glass for electrode coating suitable for insulatingly coating electrodes such as silver, ITO (indium oxide doped with tin), tin oxide, zinc oxide, aluminum and chromium formed on a glass substrate, The present invention also relates to a method for manufacturing a glass substrate with a partition wall used for manufacturing a plasma display device (hereinafter referred to as PDP).

  In recent years, thin flat panel color display devices have attracted attention. In such a display device, an electrode is formed in each pixel in order to control a display state in the pixel forming the image. As such an electrode, silver, ITO, tin oxide, aluminum, chromium, or the like is used.

  The electrodes formed on the surface of the glass substrate used as the display surface of the display device are processed into thin lines in order to realize a fine image. In order to control each pixel independently, it is necessary to ensure insulation between such finely processed electrodes. However, when moisture is present on the surface of the glass substrate or when an alkali component is present in the glass substrate, a slight current may flow through the surface of the glass substrate. In order to prevent such a current, it is effective to form an insulating layer between the electrodes. Various insulating materials for forming such an insulating layer are known, and among these, glass materials that are highly reliable insulating materials are widely used. In many cases, the glass containing lead is used for the said insulating layer for a coating | cover from points, such as sinterability and insulation.

In addition to electrical insulation as described above, the electrode coating glass typically has a softening point (Ts) of 450 to 600 ° C., and an average coefficient of linear expansion (α at 50 to 350 ° C. ) Is 60 × 10 ^{−7 to} 90 × 10 ⁻⁷ / ° C., etc., and various glasses have been conventionally proposed.
In recent years, glass containing no lead has been desired. For example, in terms of mass percentage, B ₂ O ₃ 34.0%, SiO ₂ 4.4%, ZnO 49.9%, BaO 3.9%, K ₂ An electrode coating glass composed of 7.8% O is disclosed (see Patent Document 1).

  In a PDP that has recently been expected as a large flat color display device, cells are defined by a front substrate, a rear substrate, and barrier ribs used as a display surface, and an image is generated by generating plasma discharge in the cells. It is formed. Electrodes are formed on the surfaces of the front substrate and the rear substrate. In order to protect the electrodes from plasma, it is necessary to cover the electrodes with glass having excellent plasma durability.

  The glass used for such electrode coating is usually used as a glass powder. For example, after adding a filler or the like to the glass powder as necessary, it is mixed with a resin, a solvent or the like to form a glass paste, which is applied to a glass substrate on which an electrode is formed and then fired. Furthermore, if necessary, a paste obtained by mixing an inorganic oxide filler is applied on a glass substrate on which an electrode is formed, fired after drying, a slurry is formed into a green sheet, and the electrode is formed The electrode is coated by a method such as laminating and baking on a glass substrate.

In the PDP, a partition wall is formed on an insulating layer (electrode covering glass layer) covering the electrode on the back substrate. Various methods for forming the partition walls have been proposed, and an etching method is known as one of them.
In the etching method, a partition wall paste is applied on an insulating layer and baked to form a partition wall forming glass layer, and then unnecessary portions for partition wall formation are exposed by patterning and selectively removed with an acid or the like. Then, the partition walls are formed (see Patent Document 2).

  In the etching method, partition walls are formed by eroding the partition-forming glass layer with an acid or the like, and in this process, a part of the electrode-covered glass layer located under the partition is also exposed to acids or the like. For this reason, the electrode coating material used for the etching method is required to have high chemical durability.

JP 2002-249343 A JP 2000-95542 A

Lead-containing glass is used as the electrode-covered glass layer used in the etching method, but if it is not included in lead, the chemical durability is reduced and the electrode-covered glass layer is easily eroded during etching. There was a problem.
An object of the present invention is to provide a lead-free glass for electrode coating that is excellent in chemical durability and can be used for electrode coating of a PDP back substrate.

The present invention, in mol% based on the following _{oxides, SiO 2 25~55%, B 2} O 3 4~25%, 5~30% ZnO, Al 2 O 3 0~10%, TiO 2 0~10 %, Li ₂ O 0-17%, Na ₂ O + K ₂ O 0-10%, Bi ₂ O ₃ 0-25%, CoO + CuO + CeO ₂ + SnO ₂ 0-3%, containing Al ₂ O ₃ In the case where B ₂ O ₃ + Al ₂ O ₃ is 26 mol% or less and TiO ₂ , Na ₂ O or K ₂ O is contained (TiO ₂ +4 mol%) ≧ (Na ₂ O + K ₂ O) A lead-free glass for coating (hereinafter sometimes referred to as first glass) is provided.

Further, in mole% based on the following _{oxides, SiO 2 25~55%, B 2} O 3 4~25%, 5~30% ZnO, Al 2 O 3 0~10%, TiO 2 2~10%, When consisting essentially of Li ₂ O 0-17%, Na ₂ O + K ₂ O 0-10%, Bi ₂ O ₃ 0-25%, CoO + CuO + CeO ₂ + SnO ₂ 0-3%, and containing Al ₂ O ₃ Provided is a lead-free glass for electrode coating (hereinafter sometimes referred to as second glass) in which B ₂ O ₃ + Al ₂ O ₃ is 26 mol% or less.
Moreover, the glass ceramics composition containing the said lead-free glass powder for electrode coating and the inorganic oxide powder of the ratio of 0.1-40 mass parts with respect to 100 mass parts of the powder is provided.

  Moreover, it is a manufacturing method of the glass substrate with a partition used for manufacture of PDP, Comprising: The electrode formed on the glass substrate is coat | covered with the said lead-free glass for electrode coating, By the etching method on the glass which coat | covered the electrode A method for manufacturing a glass substrate with a partition wall for forming a partition wall is provided.

  Moreover, it is a manufacturing method of the glass substrate with a partition used for manufacture of PDP, Comprising: The electrode formed on the glass substrate by the green paste containing the said glass ceramic composition, or the glass paste containing the same glass ceramic composition Provided is a method for producing a glass substrate with a partition, which is coated and fired, and a partition is formed by etching on the green sheet or glass paste fired body.

  According to the present invention, glass used for electrode coating when performing partition formation using an etching method can be made to contain no lead.

The lead-free glass for electrode coating of the present invention (hereinafter referred to as the glass of the present invention) is usually used in a powder form.
For example, the glass powder of the present invention, or a glass ceramic composition in which an inorganic oxide filler is added to the glass powder of the present invention to adjust optical properties, electrical properties or color tone, an organic vehicle for imparting printability, etc. The glass paste is applied to the electrode formed on the glass substrate and fired to coat the electrode.
The organic vehicle is obtained by dissolving a binder such as ethyl cellulose in an organic solvent such as α-terpineol. Moreover, you may coat | cover an electrode using not only a glass paste but the green sheet method as stated above.

In the PDP, the glass of the present invention is suitably used for coating a silver electrode.
Production of the PDP using the glass of the present invention is carried out as follows, for example, in the case of an alternating current type.
A patterned transparent electrode and a bus wire (typically a silver wire) are formed on the surface of a glass substrate, and a glass for transparent electrode coating glass is applied and fired thereon by a glass paste method or a green sheet method. A layer is formed, and finally a magnesium oxide layer is formed as a protective film to form a front substrate.

On the other hand, a patterned address electrode is formed on the surface of another glass substrate, and the glass powder of the present invention or a mixture of the glass powder of the present invention and an inorganic oxide powder (glass ceramic composition) is formed on the glass paste. Then, a glass layer or a glass-containing layer (hereinafter also referred to as a glass layer) is formed, and a partition wall is formed thereon by an etching method or a sand blast method.
When the partition walls are formed by the etching method, the conventional lead-free glass for electrode coating easily eroded, but the problem is eliminated or reduced by using the glass of the present invention.

After the partition walls are formed to form a glass substrate with partition walls, the phosphor layer is further printed and baked to form a back substrate. The glass layer may be formed by using a green sheet method or the like without using glass paste.
A sealant is applied to the peripheral edges of the front substrate and the rear substrate with a dispenser, assembled so that the transparent electrode and the address electrode face each other, and then baked to form a PDP. Then, the inside of the PDP is exhausted, and a discharge gas such as Ne or He—Xe is sealed in the discharge space (cell).
In addition, although said example is a thing of an alternating current system, the glass of this invention is applicable also to a direct current system.

  It is preferable that Ts of the glass of this invention is 450-600 degreeC. If it exceeds 600 ° C., a glass substrate (glass transition point: 550 to 620 ° C.) usually used may be deformed during firing.

As the glass substrate, those having α of 80 × 10 ^{−7 to} 90 × 10 ⁻⁷ / ° C. are usually used. Therefore, in order to match the expansion characteristics with such a glass substrate and prevent warpage of the glass substrate and a decrease in strength, α of the fired body of the glass of the present invention or the ceramic composition of the present invention is preferably 60 × 10. ^{It is −7 to} 90 × 10 ⁻⁷ / ° C., more preferably 70 × 10 ^{−7 to} 85 × 10 ⁻⁷ / ° C.
The glass of the present invention preferably has Ts of 450 to 600 ° C. and α of 60 × 10 ^{−7 to} 90 × 10 ⁻⁷ / ° C.

The specific resistance (ρ) at 250 ° C. of the glass of the present invention is preferably 10 ⁹ Ωcm or more. If it is less than 10 ⁹ Ωcm, electrical insulation failure may occur.

Next, the composition of the glass of the present invention will be described using a mole percentage display.
SiO ₂ is a component that improves chemical durability and is essential. When SiO ₂ is less than 25%, the chemical durability is lowered, preferably 30% or more, more preferably 35% or more. If SiO ₂ exceeds 55%, Ts is high, preferably 50% or less, more preferably 48% or less.

B ₂ O ₃ is a component that can stabilize the glass without increasing Ts as much as SiO ₂ and is essential. When B ₂ O ₃ is less than 4%, Ts is high, preferably 6% or more, and more preferably 8% or more. If B ₂ O ₃ exceeds 25%, the chemical durability is lowered, preferably 20% or less, more preferably 18% or less.

  ZnO is a component that lowers Ts and is essential. If ZnO is less than 5%, Ts becomes high, preferably 9% or more, more preferably 11% or more. If ZnO exceeds 30%, the chemical durability decreases, and crystals tend to precipitate during firing, preferably 28% or less, more preferably 27% or less, particularly preferably 26% or less, typically 24%. % Or less.

Al ₂ O ₃ is not essential, but may be contained up to 10% in order to stabilize the glass. When Al ₂ O ₃ exceeds 10%, Ts becomes high, preferably 8% or less, more preferably 5% or less.
When Al ₂ O ₃ is contained, the content is preferably 1% or more.
Further, the total content _{B 2 O 3 + Al 2 O} 3 in that case _B 2 _{O 3} and _Al 2 _{O 3} is not more than 26%. If it exceeds 26%, the chemical durability is lowered.

In the first glass, TiO ₂ is not essential, but may be contained up to 10% for the purpose of improving chemical durability, and the content in that case is typically 2% or more. If TiO ₂ exceeds 10%, the glass tends to be devitrified, preferably 8% or less, more preferably 7% or less.
In the second glass, TiO ₂ is a component that improves chemical durability and is essential. TiO ₂ is typically less than 3%, preferably 3.2% or more. If TiO ₂ exceeds 10%, the glass tends to be devitrified, preferably 8% or less, more preferably 7% or less.

Li ₂ O is not essential, but has an effect of lowering Ts and may be contained up to 17%. If Li ₂ O exceeds 17%, α becomes too large, preferably 15% or less, and typically 13% or less. When Li ₂ O is contained, the content is preferably 2% or more. If Li ₂ O is less than 2%, the effect of lowering Ts is small, preferably 4% or more.
Both Na ₂ O and K ₂ O are not essential, but either or both may be contained in a total range of up to 10% in order to reduce Ts. If Na ₂ O + K ₂ O exceeds 10%, the chemical durability decreases, or α becomes too large, preferably 8% or less, more preferably 7% or less, and typically 6% or less.

In the first glass, in order to improve chemical durability, when TiO ₂ , Na ₂ O or K ₂ O is contained, the value obtained by adding 4 mol% to the TiO ₂ content is Na ₂ O and K It is set to be equal to or more than the total content of ₂ O. For example, when not containing TiO ₂ and containing Na ₂ O or K ₂ O, Na ₂ O + K ₂ O is 4% or less. (TiO ₂ + 2%) is preferably (Na ₂ O + K ₂ O) or more.
When it is desired to lower Ts in the first glass, it is preferable not to contain TiO ₂ or to contain it in a range of less than 2%.

Bi ₂ O ₃ is not essential, but may be contained up to 25% in order to reduce Ts. If Bi ₂ O ₃ exceeds 25%, α tends to be high, preferably 20% or less, more preferably 15% or less. When Bi ₂ O ₃ is contained, the content is preferably 1% or more. If Bi ₂ O ₃ is less than 1%, the effect of lowering Ts is small.

CoO, CuO, CeO ₂ and SnO ₂ are not essential, but when one or more of these components are contained, the total content of these four components is 3% or less.
CoO, CuO, and CeO ₂ are suitable components when it is desired to suppress the silver coloring phenomenon, and one or more of these components may be contained up to 2% in total.
SnO ₂ is a suitable component for improving weather resistance, and may be contained up to 2%.

In the second glass, typically, SiO ₂ is 30 to 50%, B ₂ O ₃ is 6 to 20%, ZnO is 9 to 28%, Al ₂ O ₃ is 0 to 8%, and TiO ₂ is 2 to 8%, Li ₂ O is ₂ to 17%, Na ₂ O + K ₂ O is 0 to 8%, and as a typical embodiment in which Bi ₂ O ₃ is contained in an amount of 1% or more, SiO ₂ is _35~48%, B 2 _{O 3} is 8 to 18%, ZnO is 11~26%, _Al 2 _{O 3} is 0 to 5%, TiO ₂ is 2~7%, Li ₂ O is 4 to 15%, Na ₂ O + K ₂ O is 0 to 6%, and Bi ₂ O ₃ is 1 to 15%.
The second glass is a suitable mode when it is desired to further improve the chemical durability.

The glass of the present invention consists essentially of the above components, but may contain other components as long as the object of the present invention is not impaired. When such components are contained, the total content thereof is preferably 10% or less, more preferably 7% or less.
Examples of the other components include MgO, CaO, SrO, BaO and the like for the purpose of stabilizing the glass. When MgO, CaO, SrO or BaO is contained, the total content of these components is preferably 5% or less.
The glass of the present invention do not contain PbO, it is preferred not to contain even _Sb 2 _{O 3.}

The raw materials were prepared and mixed so as to have a composition expressed in mole percentages in the columns from SiO ₂ to BaO in the table, and melted for 1 hour using a platinum crucible in an electric furnace at 1200 to 1350 ° C. After forming into glass, it was pulverized with a ball mill to obtain glass powder. The B + Al column of the table shows B ₂ O ₃ + Al ₂ O ₃ .
Examples 1 to 9 are examples, and examples 10 to 19 are comparative examples.

For these glass powders, the softening point Ts (unit: ° C.) and the average linear expansion coefficient α (unit: 10 ⁻⁷ / ° C.) were measured as described below. The results are shown in the table.
Ts: Measured using a differential thermal analyzer in the range up to 800 ° C.
α: After the glass powder is pressure-molded, a fired body obtained by firing at a temperature 30 ° C. higher than Ts for 10 minutes is processed into a cylindrical shape having a diameter of 5 mm and a length of 2 cm, and an average of 50 to 350 ° C. with a thermal dilatometer. The linear expansion coefficient was measured.

Moreover, each glass powder 70g of Examples 1-19 and 10g of titania powders were knead | mixed with 20g of organic vehicles, and the glass paste was produced. The organic vehicle was prepared by dissolving 12% of ethyl cellulose in α-terpineol in terms of mass percentage.
Next, a glass substrate having a size of 50 mm × 75 mm and a thickness of 2.8 mm was prepared. The glass substrate has a mass percentage display composition of SiO ₂ 58%, Al ₂ O ₃ 7%, Na ₂ O 4%, K ₂ O 6.5%, MgO 2%, CaO 5%, SrO 7%. BaO 7.5%, ZrO ₂ 3%, and a glass transition point of 626 ° C. and α of 83 × 10 ⁻⁷ / ° C.

The glass paste was uniformly screen-printed on a 50 mm × 50 mm portion of the glass substrate, and then dried at 120 ° C. for 10 minutes. These glass substrates were heated at a heating rate of 10 ° C./min until the temperature reached Ts, and further, the temperature was maintained at Ts for 10 minutes to be fired. Thus, the thickness of the glass layer formed on the glass substrate was 10-15 micrometers.
The chemical durability of the sample having the glass layer formed on the glass substrate was measured as described below. The results are shown in the table.

  Chemical durability: The sample was immersed in a 3.0% by mass nitric acid solution maintained at 42 ° C. for 90 seconds, and the chemical durability was evaluated by the degree of decrease in film thickness before and after immersion. Those having preferable durability were indicated as ◯, those having a decrease in film thickness and inferior in durability were indicated by Δ, and those in which the fired film itself disappeared and extremely inferior were indicated as ×. In the above evaluation, among those having preferable durability, those in which no change in the properties of the fired film surface was observed even when the immersion time was 180 seconds were marked as ◎ as having high durability.

  It can be used for electrode coating on the back substrate of the PDP and for the back substrate.

Claims (11)

In mole% based on the following _{oxides, SiO 2 25~55%, B 2} O 3 4~25%, 5~30% ZnO, Al 2 O 3 0~10%, TiO 2 0~10%, Li 2 O _{2 to} 17%, Na ₂ O + K ₂ O 0 to 10%, Bi ₂ O ₃ 0 to 25%, CoO + CuO + CeO ₂ + SnO ₂ 0 to 3%, and when Al ₂ O ₃ is contained, B ₂ Lead-free glass for electrode coating in which O ₃ + Al ₂ O ₃ is 26 mol% or less and contains TiO ₂ , Na ₂ O or K ₂ O (TiO ₂ +4 mol%) ≧ (Na ₂ O + K ₂ O) . SiO ₂ 30 to 50 _mol%, B 2 _{O 3} 6 to 20 mol%, ZnO is 9 to 27 mol%, TiO ₂ 0 to 8 mol%, Li ₂ O 2 to 15 mol%, _Na 2 O + K _The lead-free glass for electrode coating according to claim 1, wherein ₂ O is 0 to 8 mol%. In mole% based on the following _{oxides, SiO 2 25~55%, B 2} O 3 4~25%, 5~30% ZnO, Al 2 O 3 0~10%, TiO 2 2~10%, Li 2 O _{2 to} 17%, Na ₂ O + K ₂ O 0 to 10%, Bi ₂ O ₃ 0 to 25%, CoO + CuO + CeO ₂ + SnO ₂ 0 to 3%, and when Al ₂ O ₃ is contained, B _{2 O 3} + _Al 2 O ₃ is for covering electrodes lead-free glass is less than 26 mol%. SiO ₂ 30 to 50 _mol%, B 2 _{O 3} 6 to 20 mol%, ZnO is 9 to 27 mol%, TiO ₂ is 2-8 mol%, Li ₂ O 2 to 15 mol%, _Na 2 O + K _The lead-free glass for electrode coating according to claim 3, wherein ₂ O is 0 to 8 mol%. Claim 3 or 4 for covering electrodes lead-free glass TiO ₂ is 3.2 mol% or more. The lead-free glass for electrode coating according to any one of claims 1 to 5, comprising 1 to 15 mol% of Bi ₂ O ₃ . SiO ₂ is 35-48 _mol%, B 2 _{O 3} is 8 to 18 mol%, ZnO is 11-27 mol%, Li ₂ O is for covering electrodes lead-free glass according to claim 6 which is 2 to 15 mol%.   A glass ceramic composition comprising the lead-free glass powder for electrode coating according to any one of claims 1 to 7 and an inorganic oxide powder in a proportion of 0.1 to 40 parts by mass with respect to 100 parts by mass of the powder. The inorganic oxide powder is selected from the group consisting of TiO ₂ , ZnO, SiO ₂ , Al ₂ O ₃ , ZrO ₂ , P ₂ O ₅ , Fe ₂ O ₃ , MnO ₂ , Cr ₂ O ₃ and Co ₂ O _3. The glass ceramic composition according to claim 8, which is a powder of one or more inorganic oxides.   A method for manufacturing a glass substrate with a partition wall used for manufacturing a plasma display device, wherein the electrode formed on the glass substrate is covered with the lead-free glass for electrode coating according to any one of claims 1 to 7, and the electrode is covered The manufacturing method of the glass substrate with a partition which forms a partition on an etched glass by an etching method.   A method for manufacturing a glass substrate with a partition wall used for manufacturing a plasma display device, wherein the electrode formed on the glass substrate is a green sheet containing the glass ceramic composition of claim 8 or 9, or the glass ceramic composition. A method for producing a glass substrate with barrier ribs, which is covered with a glass paste and fired, and a barrier rib is formed by etching on the green sheet or the fired body of the glass paste.