JP2007112686A - Electrode coating glass and plasma display panel - Google Patents

Abstract

An object of the present invention is to provide a glass for electrode coating which does not contain PbO and contains Bi ₂ O ₃ and which can suppress silver coloring when coated with a silver electrode.
An electrode coating glass containing Bi ₂ O ₃ and not containing PbO, which contains CeO ₂ and MnO ₂ . By _{mol%, B 2 O 3 25~60%,} SiO 2 0~18%, 0~60% ZnO, MgO + CaO + SrO + BaO 7~18%, Bi 2 O 3 3~15%, Al 2 O 3 0~10% , CeO ₂ 0.05 to 0.2%, MnO ₂ 0.05 to 0.2%, and glass for electrode coating that does not contain PbO.
[Selection figure] None

Description

  The present invention relates to a plasma display panel (PDP) and an electrode coating glass suitable for coating a transparent electrode or the like formed on a glass substrate of the 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, a transparent electrode such as an ITO or tin oxide thin film formed on a glass substrate and a thick film type Ag electrode or a thin film type Cr—Cu—Cr electrode are used in order to prevent deterioration in image quality. It has been.

The transparent electrode formed on the surface of the glass substrate used as the display surface of the display device is processed into a thin line shape in order to realize a fine image. And in order to control each pixel independently, it is necessary to ensure the insulation between such finely processed transparent 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 transparent electrodes. The insulating layer is preferably transparent in order to prevent deterioration in image quality due to the insulating layer formed between the transparent electrodes.
Various insulating materials for forming such an insulating layer are known. Among them, glass materials that are transparent and highly reliable insulating materials are widely used.

  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. A transparent electrode is formed on the surface of the front substrate, and an electrode called a bus electrode is formed to supplement the conductivity of the transparent electrode. As this bus electrode, an Ag electrode, a Cr—Cu—Cr electrode, or the like is used. In order to protect the transparent electrode and the bus electrode from plasma discharge, it is essential to cover the electrode 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 a transparent electrode or the like is formed and then fired. A slurry obtained by mixing a resin and, if necessary, a filler or the like is formed into a green sheet, laminated on a glass substrate on which a transparent electrode or the like is formed, and then fired. Coating.

Currently, PbO-containing glass is used as an electrode coating glass for PDP. However, development has been made to make this a glass that does not contain PbO (for example, Patent Document 1).
Patent Document 1 discloses that the occurrence of yellowing (hereinafter referred to as silver coloration) caused by a bus electrode in a dielectric layer (corresponding to the insulating layer) of a PDP can be reduced in terms of mass percentage, Bi ₂ O. _{3 25~50%, 10~20% ZnO,} BaO 5~20%, B 2 O 3 5~35%, SiO 2 0~15%, Al 2 O 3 0~10%, the glass powder having a composition of Including PDP dielectric materials are described.

JP 2003-226549 A

Bi ₂ O ₃ based lead-free glass as described in Patent Document 1 is relatively easy to match its dielectric constant with the dielectric constant of PbO-containing glass currently used as PDP electrode coating glass, In this case, since the capacitance of the PDP cell does not change, the conventional driving circuit can be used.
On the other hand, in recent years, there has been a demand for further suppression of the silver color development.
An object of the present invention is to provide a glass for electrode coating which is Bi ₂ O ₃ based lead-free glass and can reduce silver coloring.

The present invention provides an electrode coating glass containing Bi ₂ O ₃ and not containing PbO, and containing CeO ₂ and MnO ₂ (hereinafter sometimes referred to as a first glass). To do.
Further, in mole% based on the following _{oxides, B 2 O 3 25~60%,} SiO 2 0~18%, 0~60% ZnO, MgO + CaO + SrO + BaO 7~18%, Bi 2 O 3 3~15%, Al ₂ O ₃ 0 to 10%, CeO ₂ 0.05 to 0.2%, MnO ₂ 0.05 to 0.2%, and a glass for electrode coating that does not contain PbO (hereinafter referred to as second glass). May be provided).

In addition, a PDP in which cells are defined by a front substrate, a rear substrate, and partition walls used as a display surface, the electrodes formed on the glass substrate constituting the front substrate or the glass substrate constituting the rear substrate A PDP in which an electrode formed in (1) is covered with the electrode coating glass is provided.
The present inventor, when coating a silver electrode with a glass for electrode coating containing Bi ₂ O ₃ and not containing PbO, contains both CeO ₂ and MnO _{2 in} the glass, so that not only silver coloring but silver It discovered that coloring of an electrode covering glass layer could be reduced, and resulted in this invention.

Silver color development or the like of PDP using electrode coating glass containing Bi ₂ O ₃ and not containing PbO can be reduced.
In addition, in a PDP in which the dielectric layer does not contain PbO, it is possible to use a current PDP drive circuit in which PbO-containing glass is used for the dielectric layer.
Further, the coloring of the dielectric layer can be reduced, and an image with high color purity can be displayed.

  The electrode coating glass of the present invention (hereinafter referred to as the glass of the present invention) is usually used in powder form. For example, the glass powder of the present invention is made into a glass paste using an organic vehicle or the like for imparting printability, and the glass paste is applied onto 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. Further, the electrode may be coated using the green sheet method as described above.

  In the PDP, a transparent electrode is formed on the glass substrate of the front substrate, and the glass of the present invention is suitably used for coating the transparent electrode. In this case, the PDP is the PDP of the present invention. The glass of the present invention can also be used for coating the opaque electrode of the PDP back substrate, and the PDP in this case is also the PDP of the present invention.

The thickness of the glass substrate used for the front substrate is usually 2.8 mm, and the transmittance (linear light transmittance) for light having a wavelength of 550 nm of the glass substrate itself is typically 90%.
The transparent electrode has, for example, a strip shape having a width of 0.5 mm, and is formed so that the strip electrodes are parallel to each other. The distance between the strip electrode center lines is, for example, 0.83 to 1.0 mm. In this case, the ratio of the transparent electrode to the surface of the glass substrate is 50 to 60%.
For the front substrate in which the transparent electrode of the PDP front substrate is coated with the glass of the present invention, the linear light transmittance (T ₅₅₀ ) for light having a wavelength of 550 nm is preferably 70% or more. If it is less than 70%, the image quality of the PDP may be insufficient.

The PDP of the present invention in which the glass of the present invention is used for electrode coating on the front substrate is manufactured as follows if it is of an alternating current type, for example.
A patterned transparent electrode and a bus electrode (typically Ag wire) are formed on the surface of the glass substrate, and the glass powder of the present invention is applied and fired thereon to form a glass layer, and finally protected. A magnesium oxide layer is formed as a 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 the glass powder of which Ts is comparable to the glass of the present invention, or the powder of these glasses A glass layer is formed by applying and firing a powder of a metal oxide such as alumina mixed with an inorganic pigment such as titania to form a glass layer, on which a barrier rib is formed in a stripe shape, a lattice shape, etc., and a phosphor layer Is printed and fired to obtain 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).
Although the above example is an AC type, the present invention can also be applied to a DC type.

It is preferable that Ts of the glass of this invention is 605 degrees C or less. If it exceeds 605 ° C., the firing temperature becomes high and the glass substrate may be deformed. The temperature is typically 580 to 600 ° C.
The glass transition point (Tg) of the glass of the present invention is preferably 480 to 500 ° C.
The average linear expansion coefficient at 50 to 350 ° C. of glass of the present invention (alpha) is preferably ^{70 × 10 -7 ~80 × 10 -7} / ℃.

  The relative dielectric constant (ε) of the glass of the present invention at 20 ° C. and 1 kHz is preferably 11.0 to 12.5. If ε is outside this range, the difference from ε of the conventionally used PbO-containing / electrode-covering glass becomes large, and the capacitance of the cell changes greatly, and the conventional drive circuit may not be usable.

It is preferable that the glass of the present invention does not contain any of Li ₂ O, Na ₂ O and K ₂ O. If any of these is contained, silver coloring or the like may become remarkable.

The first glass of the present invention contains both CeO ₂ and MnO ₂ . If it does not contain any of these, silver coloration or the like becomes remarkable, or coloring of the electrode-coated glass layer becomes strong.
Typically, the contents of CeO ₂ and MnO ₂ are 0.05 to 0.2 mol% and 0.05 to 0.2 mol%, respectively, and 0.15 to 0.35% and 0.0. It is 05 to 0.15%.

The composition of the second glass of the present invention will be described below with mol% simply expressed as%.
B ₂ O ₃ is a glass network former and is essential. If it is less than 25%, the transmittance of the glass layer obtained by firing (hereinafter sometimes simply referred to as transmittance) tends to decrease. Typically 28% or more. If it exceeds 60%, the transmittance tends to decrease. Preferably it is 35% or less, typically 32% or less.
SiO ₂ is not essential, but may be contained up to 18% for glass stabilization. If it exceeds 18%, the transmittance tends to decrease. When SiO ₂ is contained, its content is typically 11 to 17%.
ZnO is not essential, but may be contained up to 60% in order to reduce Ts. If it exceeds 60%, the glass becomes unstable. Typically 35% or less. When ZnO is contained, its content is preferably 27% or more, and typically 29% or more.

MgO, CaO, SrO and BaO are components that lower Ts, and must contain at least one component. If the total content of these four components is less than 7%, the transmittance tends to decrease. If it exceeds 18%, α tends to be large.
Of the four components, BaO is preferably contained. When BaO is contained, its content is preferably 7 to 16%, typically 10 to 14%.
When it is desired to loosen the viscous behavior of the glass, it is preferable to contain MgO.
When CaO is contained, the content is preferably 9% or less. If it exceeds 9%, the transmittance tends to decrease.

Bi ₂ O ₃ is a component that lowers Ts and is essential. If it is less than 3%, Ts becomes high. Typically 7% or more. If it exceeds 15%, α or ε may increase. Typically 10% or less.
Al ₂ O ₃ is not essential, but may be contained up to 10% in order to stabilize the glass. If it exceeds 10%, the transmittance tends to decrease. Typically 5% or less. When Al ₂ O ₃ is contained, its content is typically 1.5% or more.
CeO ₂ and MnO ₂ are components that prevent silver coloring and the like from becoming prominent and prevent the electrode-coated glass layer from becoming strongly colored, both of which are essential. Typically, both are 0.05 to 0.15%.

In a preferred embodiment, B ₂ O ₃ is 25 to 35%, ZnO is 27 to 60%, BaO is 7 to 16%, Bi ₂ O ₃ is 3 to 10%, and Al ₂ O ₃ is 0 to 5%. Typically, B ₂ O ₃ is 28 to 32%, SiO ₂ is 11 to 17%, ZnO is 29 to 35%, BaO is 10 to 14%, and Bi ₂ O ₃ is 7 to 10%. %.

Although the 2nd glass of this invention consists essentially of the said component, you may contain another component in the range which does not impair the objective of this invention. In that case, the total content of the other components is preferably 4% or less.
Examples of such components include CoO, CuO, TiO ₂ , SnO ₂ for the purpose of promoting the decomposition of the resin, La ₂ O ₃ for the purpose of adjusting ε, and the like.

The second glass of the present invention does not contain PbO, it is preferred not to contain even P ₂ O ₅ in the other. If P ₂ O ₅ is contained, the transmittance may decrease.
Moreover, when it contains CuO, it is preferable that the content is 0.3% or less. If it exceeds 0.3%, the transmittance may decrease.
When TiO ₂ is contained, the content is preferably 2% or less. If it exceeds 2%, the glass may become unstable or the transmittance may be lowered.

The raw materials were prepared and mixed so as to have a composition represented by mol% in the column from B ₂ O ₃ to MnO _{2 in} Table 1, and melted for 1 hour using a platinum crucible in an electric furnace at 1200 to 1350 ° C. After forming into thin glass, it was pulverized with a ball mill and classified by air classification to obtain glass powder. Examples 1 to 3 are examples, and examples 4 to 9 are comparative examples. Examples 8 and 9 are included in the glass composition range described in Patent Document 1 and the mass percentage display compositions are shown in Table 2.

Tg (unit: ° C.), Ts (unit: ° C.), α (unit: 10 ⁻⁷ / ° C.), and ε were measured for these glasses as follows. The results are shown in Table 1.
Tg, Ts: measured using a differential thermal analyzer.
α: After the glass powder is molded, a sintered body obtained by firing at 580 ° C. for 10 minutes is processed into a cylindrical shape having a diameter of 5 mm and a length of 2 cm, and an average linear expansion at 50 to 350 ° C. with a thermal dilatometer The coefficient was measured.
ε: Molten glass was gradually cooled and formed into a plate shape, cut and polished into a diameter shape with a diameter of 50 mm and a thickness of 3 mm, and gold electrodes were formed on both surfaces thereof by a vacuum deposition method to prepare a sample. The relative dielectric constant of this sample at 20 ° C. and 1 kHz was measured using an LCR meter.

  A glass paste was prepared by kneading 32.5 g of the glass powder with 12.5 g of an organic vehicle. The organic vehicle was prepared by dissolving 10% ethyl cellulose in α-terpineol in terms of mass percentage.

  Two glass substrates (PD200 manufactured by Asahi Glass Co., Ltd.) having a size of 50 mm × 75 mm and a thickness of 2.8 mm were prepared. The glass paste is uniformly applied to a 48 mm × 38 mm portion of the top surface of the glass substrate manufactured by the float process (the surface not in contact with molten tin at the time of float forming) using a metal mask having a thickness of 100 μm or 125 μm. The blade was coated and dried at 120 ° C. for 10 minutes. These glass substrates were heated at a heating rate of 10 ° C./min until the temperatures reached 570 ° C. and 590 ° C., respectively, held at that temperature for 30 minutes, and fired. Thus, the thickness of the glass layer formed on the glass substrate was 20-30 micrometers.

  About these glass substrates with a glass layer, the transmittance | permeability of the linear light of wavelength 550nm was measured as described below. The results are shown in Table 1. T (570 ° C.) and T (590 ° C.) are transmittances when fired at 570 ° C. and 590 ° C., respectively.

  Transmittance: The transmittance of linear light having a wavelength of 550 nm was measured using a self-recording spectrophotometer U-4100 manufactured by Hitachi, Ltd. (the state where there was no sample was taken as 100%). This transmittance is preferably 70% or more.

Separately, two glass substrates (PD200 manufactured by Asahi Glass Co., Ltd.) having a size of 50 mm × 75 mm and a thickness of 2.8 mm were prepared.
Silver paste NP-4028A of Noritake Company Limited was screen-printed on a 46 mm × 32 mm portion of the top surface of these glass substrates, and then dried and fired to produce a silver layer-formed glass substrate.

  The glass paste is uniformly blade-coated on a 48 mm × 38 mm portion of the surface on which the silver layer is formed using a metal mask having a thickness of 100 μm or 125 μm so as to cover the silver layer of the silver layer-formed glass substrate. Dry at 10 ° C. for 10 minutes. These glass substrates were heated at a heating rate of 10 ° C./min until the temperatures reached 570 ° C. and 590 ° C., respectively, held at that temperature for 30 minutes, and fired. The thickness of the obtained glass layer was 20-30 micrometers.

About these, L value, a value, and b value were measured using the spectrocolorimeter. That is, the glass substrate was placed so that the surface on which the glass layer was formed on the white reference plate was the measurement surface, and the L value, a value, and b value were measured using a spectrocolorimeter manufactured by Minolta. Table 1 shows the b value when baked at 570 ° C and 590 ° C.
The b value is preferably 12 or less. If it exceeds 12, suppression of silver coloring or the like is insufficient.

Further, ΔL, Δa, and Δb were measured as follows in order to examine the degree of coloring by the glass layer having a thickness of 25 μm.
First, two glass substrates (PD200 manufactured by Asahi Glass Co., Ltd.) having a size of 50 mm × 75 mm and a thickness of 2.8 mm were prepared.
The glass paste is uniformly blade-coated on a 48 mm × 38 mm portion of the top surface of these glass substrates using a metal mask having a thickness of 100 μm on one glass substrate and a thickness of 125 μm on the other glass substrate. Dried for minutes.

Thereafter, the mixture was heated at a heating rate of 10 ° C./min until the temperature reached 590 ° C., held at that temperature for 30 minutes and fired to obtain a glass substrate with a glass layer. The thickness of the obtained glass layer was about 20 μm and about 30 μm, respectively.
About these two glass substrate with a glass layer, L value, a value, and b value were measured like the silver layer formation glass substrate with a glass layer previously. The L value, a value, and b of the glass substrate with a glass layer having a thickness of 25 μm by interpolation from the L value, a value, and b value of the glass substrate having a glass layer thickness of about 20 μm and about 30 μm. The value was determined.
Moreover, L value, a value, and b value were measured also about the glass substrate which has not formed the glass layer.

  Values obtained by subtracting the L value, a value, and b value of the glass substrate on which the glass layer is not formed from the L value, a value, and b value of the glass substrate with the glass layer having a glass layer thickness of 25 μm ΔL, Δa, Δb Is shown in Table 1. Δa is preferably −0.5 to +0.5. If it is less than −0.5, green coloring is strong, and if it exceeds +0.5, red coloring is strong. Δb is preferably −2.0 to +2.0. If it is less than −2.0, blue coloring is strong, and if it exceeds +2.0, yellow coloring is strong.

It can be used for electrode coating of a PDP substrate.

Claims (6)

A glass for electrode coating containing Bi ₂ O ₃ and not containing PbO, the glass for electrode coating containing CeO ₂ and MnO ₂ . In mole% based on the following _{oxides, B 2 O 3 25~60%,} SiO 2 0~18%, 0~60% ZnO, MgO + CaO + SrO + BaO 7~18%, Bi 2 O 3 3~15%, Al 2 O _{3 0~10%, CeO 2 0.05~0.2%} , MnO 2 0.05~0.2%, glass for covering electrodes containing no PbO consisting essentially. In the above display, B ₂ O ₃ is 25 to 35%, ZnO is 27 to 60%, BaO is 7 to 16%, Bi ₂ O ₃ is 3 to 10%, and Al ₂ O ₃ is 0 to 5%. The electrode coating glass according to claim 2. In the display, B ₂ O ₃ is 28 to 32%, SiO ₂ is 11 to 17%, ZnO is 29 to 35%, BaO is 10 to 14%, and Bi ₂ O ₃ is 7 to 10%. 3. The electrode coating glass according to 3. Li ₂ O, glass for covering electrodes according to claim 1 which does not contain any Na ₂ O and _{K 2} O. A plasma display panel in which cells are defined by a front substrate, a rear substrate and partition walls used as a display surface, the electrodes formed on the glass substrate constituting the front substrate or the glass substrate constituting the rear substrate A plasma display panel in which the electrode formed on the electrode is covered with the electrode coating glass according to claim 1.