JP2012248289A - Plasma display panel and dielectric paste - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plasma display panel that ensures high reliability in view of an environmental problem and to provide a dielectric paste that forms a dielectric layer thereof.SOLUTION: The dielectric paste includes a glass component, a resin component and solvent. The glass component substantially contains no bismuth component nor lead component. The glass component is comprised of glass powder with a value of 10% cumulative grain size D10 of over 1.0 μm to 1.3 μm exclusive.

Description

  The present invention relates to a plasma display panel and a dielectric paste used for display devices and the like.

  A plasma display panel (hereinafter referred to as a PDP) can realize a high definition and a large screen, and thus a 100-inch class television or the like has been commercialized. In recent years, PDP has been applied to high-definition televisions that have more than twice the number of scanning lines compared to conventional NTSC systems, and PDPs that do not contain lead components have been commercialized in consideration of environmental issues. .

  A PDP basically includes a front plate and a back plate. The front plate covers a display electrode composed of a glass substrate of sodium borosilicate glass by a float method, a striped transparent electrode and a bus electrode formed on one main surface of the glass substrate, and the display electrode. The dielectric layer functions as a capacitor, and a protective layer made of magnesium oxide (MgO) formed on the dielectric layer. On the other hand, the back plate is a glass substrate, stripe-shaped address electrodes formed on one main surface thereof, a base dielectric layer covering the address electrodes, a partition formed on the base dielectric layer, It is comprised with the fluorescent substance layer which light-emits each of red, green, and blue formed between the partition walls.

  The front plate and the back plate are hermetically sealed with their electrode forming surfaces facing each other, and Ne—Xe discharge gas is sealed at a pressure of 55 kPa to 80 kPa in a discharge space partitioned by a partition wall. PDP discharges by selectively applying a video signal voltage to the display electrodes, and the ultraviolet rays generated by the discharge excite each color phosphor layer to emit red, green, and blue light, thereby realizing color image display doing.

  Silver electrodes for ensuring conductivity are used for the bus electrodes of the display electrodes, and low-melting glass mainly composed of lead oxide is used for the dielectric layer. However, due to recent environmental concerns An example in which a lead component is not included as a dielectric layer is disclosed (for example, see Patent Document 1).

JP 2003-128430 A

  In recent years, PDP has been increasingly applied to high-definition televisions having twice or more scanning lines as compared with the conventional NTSC system.

  As a result of such high definition, the number of scanning lines is increased, the number of display electrodes is increased, and the display electrode interval is further reduced. Therefore, it is necessary that the dielectric layer covering the display electrode also has a small gap between the display electrodes and has a smooth film surface. If there are voids, film surface defects, etc., the dielectric strength characteristics required for the dielectric layer will deteriorate.

  On the other hand, from the viewpoint of increasing the efficiency of the PDP, it is desirable that the dielectric constant of the dielectric layer of the front plate is low. This is because if the dielectric constant of the dielectric layer is low, the generation efficiency of ultraviolet rays is improved, which contributes to lower power consumption of the PDP. Here, by removing Bi, which is a heavy element, in the glass composition of the dielectric layer, a low dielectric constant of about 5 to 7 can be obtained. However, by removing Bi, various physical property temperatures such as glass transition point, yield point, and softening point are also increased. Such a glass having a large physical property temperature difference is called a long glass. In the case of a glass composition having a high softening point, the firing temperature for firing the dielectric layer also requires high-temperature firing to obtain a high transmittance, and a large amount of energy for firing is also required. Conventionally, the temperature of the part that promotes and accelerates the sintering of glass in the firing process is as low as possible near the softening point in order to suppress gas generation from residual organic matter in the display electrode. However, since glass with a low dielectric constant composition is a long glass with a large temperature difference between physical properties, sufficient sintering cannot be obtained at this temperature, which may cause film surface defects. is there. At the film surface defect portion, the withstand voltage is insufficient, which causes a withstand voltage failure during lighting.

  An object of the present invention is to solve such problems and to realize a PDP that secures high luminance and high reliability even in high-definition display and further considers environmental problems.

  In order to achieve the above object, the dielectric paste of the present invention includes a glass component, a resin component and a solvent, the glass component substantially does not contain a bismuth component and a lead component, and the glass component is It is characterized by comprising a glass powder having a 10% cumulative particle size D10 value of greater than 1.0 μm and less than 1.3 μm. The PDP of the present invention has a dielectric layer formed by this dielectric layer paste.

  As described above, according to the present invention, it is possible to realize a PDP that ensures high reliability and further considers environmental problems.

The perspective view which shows the structure of PDP in embodiment of this invention Sectional drawing which shows the structure of the front plate of the PDP

  Hereinafter, a PDP according to an embodiment of the present invention will be described with reference to the drawings.

(Embodiment)
FIG. 1 is a perspective view showing the structure of a PDP according to an embodiment of the present invention. The basic structure of the PDP is the same as that of a general AC surface discharge type PDP. As shown in FIG. 1, the PDP 1 has a front plate 2 made of a front glass substrate 3 and a back plate 10 made of a back glass substrate 11 facing each other, and its outer peripheral portion is sealed with a glass frit or the like. The material is hermetically sealed. The discharge space 16 inside the sealed PDP 1 is filled with a discharge gas such as Ne and Xe at a pressure of 55 kPa to 80 kPa.

  On the front glass substrate 3 of the front plate 2, a pair of strip-like display electrodes 6 made up of scanning electrodes 4 and sustain electrodes 5 and black stripes (light-shielding layers) 7 are arranged in a plurality of rows in parallel with each other. A dielectric layer 8 serving as a capacitor is formed on the front glass substrate 3 so as to cover the display electrode 6 and the light shielding layer 7, and a protective layer 9 made of magnesium oxide (MgO) is formed on the surface. Has been.

  On the back glass substrate 11 of the back plate 10, a plurality of strip-like address electrodes 12 are arranged in parallel to each other in a direction orthogonal to the scanning electrodes 4 and the sustain electrodes 5 of the front plate 2. Layer 13 is covering. Further, a partition wall 14 having a predetermined height is formed on the base dielectric layer 13 between the address electrodes 12 to divide the discharge space 16. For each address electrode 12, a phosphor layer 15 that emits red, blue, and green light by ultraviolet rays is sequentially applied to the grooves between the barrier ribs 14 and formed. A discharge cell is formed at a position where the scan electrode 4 and the sustain electrode 5 intersect with the address electrode 12, and the discharge cell having red, blue and green phosphor layers 15 arranged in the direction of the display electrode 6 is used for color display. Become a pixel.

FIG. 2 is a cross-sectional view of front plate 2 showing the configuration of dielectric layer 8 of the PDP in the embodiment of the present invention. 2 is shown upside down from FIG. As shown in FIG. 2, display electrodes 6 and black stripes 7 made of scanning electrodes 4 and sustain electrodes 5 are formed in a pattern on a front glass substrate 3 manufactured by a float process or the like. Scan electrode 4 and sustain electrode 5 are made of transparent electrodes 4a and 5a made of indium tin oxide (ITO) or tin oxide (SnO ₂ ), respectively, and metal bus electrodes 4b and 5b formed on transparent electrodes 4a and 5a. It is comprised by. The metal bus electrodes 4b and 5b are used for the purpose of imparting conductivity in the longitudinal direction of the transparent electrodes 4a and 5a, and are formed of a conductive material whose main component is a silver (Ag) material.

  The dielectric layer 8 is formed so as to cover these transparent electrodes 4a and 5a, the metal bus electrodes 4b and 5b and the black stripe 7 formed on the front glass substrate 3, and a protective layer 9 is further formed on the dielectric layer 8. Forming.

  Next, a method for manufacturing a PDP will be described. First, the scan electrode 4, the sustain electrode 5, and the light shielding layer 7 are formed on the front glass substrate 3. The transparent electrodes 4a and 5a and the metal bus electrodes 4b and 5b are formed by patterning using a photolithography method or the like. The transparent electrodes 4a and 5a are formed using a thin film process or the like, and the metal bus electrodes 4b and 5b are solidified by baking a paste containing a silver (Ag) material at a desired temperature. Similarly, the light-shielding layer 7 is formed by screen printing a paste containing a black pigment or by forming a black pigment on the entire surface of the glass substrate, and then patterning and baking using a photolithography method.

  Next, a dielectric paste is applied on the front glass substrate 3 by a die coating method or the like so as to cover the scan electrode 4, the sustain electrode 5, and the light shielding layer 7, thereby forming a dielectric paste layer (dielectric material layer). After the dielectric paste is applied, the surface of the applied dielectric paste is leveled by leaving it to stand for a predetermined time, so that a flat surface is obtained. Thereafter, the dielectric paste layer is baked and solidified to form the dielectric layer 8 that covers the scan electrode 4, the sustain electrode 5, and the light shielding layer 7. The dielectric paste is a paint containing a dielectric material such as glass powder, a binder and a solvent. Next, a protective layer 9 made of magnesium oxide (MgO) is formed on the dielectric layer 8 by a vacuum deposition method. Through the above steps, predetermined components (scanning electrode 4, sustaining electrode 5, light shielding layer 7, dielectric layer 8, and protective layer 9) are formed on front glass substrate 3, and front plate 2 is completed.

  On the other hand, the back plate 10 is formed as follows. First, the structure for the address electrode 12 is formed by a method of screen printing a paste containing silver (Ag) material on the rear glass substrate 11 or a method of patterning using a photolithography method after forming a metal film on the entire surface. An address electrode 12 is formed by forming a material layer to be an object and firing it at a desired temperature. Next, a dielectric paste is applied on the rear glass substrate 11 on which the address electrodes 12 are formed by a die coating method so as to cover the address electrodes 12 to form a dielectric paste layer. Thereafter, the base dielectric layer 13 is formed by firing the dielectric paste layer. The dielectric paste is a paint containing a dielectric material such as glass powder, a binder and a solvent.

  Next, a partition wall forming paste including a partition wall material is applied on the base dielectric layer 13 and patterned into a predetermined shape to form a partition wall material layer and then fired to form the partition walls 14. Here, as a method of patterning the partition wall paste applied on the base dielectric layer 13, a photolithography method or a sand blast method can be used. Next, the phosphor layer 15 is formed by applying a phosphor paste containing a phosphor material on the base dielectric layer 13 between the adjacent barrier ribs 14 and on the side surfaces of the barrier ribs 14 and baking it. Through the above steps, the back plate 10 having predetermined components on the back glass substrate 11 is completed.

  In this way, the front plate 2 and the back plate 10 having predetermined constituent members are arranged to face each other so that the scanning electrodes 4 and the address electrodes 12 are orthogonal to each other, and the periphery thereof is sealed with a glass frit, so that the discharge space 16 is filled with a discharge gas containing Ne, Xe or the like, thereby completing the PDP 1.

  Next, the dielectric layer 8 of the front plate 2 will be described in detail. As described above, the dielectric layer is required to have a high withstand voltage, but is required to have a high light transmittance. This characteristic greatly depends on the composition of the glass component contained in the dielectric layer.

In the past, in order to enable firing at about 450 ° C. to 600 ° C., the glass component contained in the dielectric layer contained 20% by weight or more of lead oxide. For consideration, the glass contains substantially no lead component and 0.5 to 40% by weight of Bi ₂ O ₃ .

As described above, Bi ₂ O ₃ is added as an alternative material for the lead component in the dielectric glass, but the softening point of the dielectric glass can be lowered by increasing the amount of Bi ₂ O ₃ added. There are various advantages to the manufacturing process. However, since Bi-based materials are expensive, increasing the amount of Bi ₂ O ₃ added will increase the cost of the raw materials used. Therefore, there is a technical example including an alkali metal oxide selected from Li, Na, K, Rb, Cs, and the like as an alternative material for the Bi-based material. Bi is an element having a large atomic weight of 209, and it is necessary to reduce the content of the glass having a large atomic weight in consideration of a low dielectric constant glass that will be required to improve the characteristics of PDP in the future.

  In contrast, the embodiment of the present invention is characterized in that Bi is not included. Therefore, the dielectric constant can be kept low, the generation efficiency of ultraviolet rays can be improved, and the power consumption of the PDP can be reduced. On the other hand, by removing Bi, various physical property temperatures such as a transition point, a yield point, and a softening point of the glass are also increased. Such a glass having a large physical property temperature difference is called a long glass. In the case of a glass composition having a high softening point, the firing temperature for firing the dielectric layer also requires high-temperature firing to obtain a high transmittance, and a large amount of energy for firing is also required.

  Conventionally, the temperature of the part that promotes and accelerates the sintering of glass in the firing process is as low as possible near the softening point in order to suppress gas generation from residual organic matter in the display electrode. However, since glass with a low dielectric constant composition is a long glass with a large temperature difference between physical properties, sufficient sintering cannot be obtained at this temperature, which may cause film surface defects. is there. At the film surface defect portion, the withstand voltage is insufficient, which causes a withstand voltage failure during lighting.

  By the way, in the case of a low dielectric constant glass composition, since the glass specific gravity is small, it is necessary to greatly increase the organic component in the paste composition in order to form a layer using conventional coating means. Here, it is not desirable to make up with only the solvent because it is difficult to sufficiently dry in the drying step. On the other hand, when filling with a resin component, it becomes easy to generate uneven distribution of resin (hereinafter referred to as “resin dama”) in the paste.

  This resin dama burns and disappears in the firing step, but at the same time, a dent-like defect is generated in the dielectric layer. In this recessed portion, the withstand voltage characteristic is lowered, and a withstand voltage failure is caused at the time of lighting. This dent is blocked by glass sintering in the firing step, and can be reduced by promoting the sintering such as raising the firing temperature. However, in the case of a long glass with a high softening point, the above-mentioned problem For this reason, it is difficult to reduce the occurrence of dents.

  In addition, the greater the amount of resin relative to the amount of glass in the paste, the greater the frequency of occurrence of dents due to resin lumps, but if the amount of resin is decreased to reduce the frequency of resin dams, the paste viscosity will decrease. There was a problem that it was difficult to obtain sufficient coatability.

  In order to solve such a problem, in the embodiment of the present invention, the dielectric paste used in the step of forming the dielectric layer 8 does not substantially contain a bismuth component and a lead component in the glass component, and the glass powder 10% cumulative particle size (D10) is greater than 1.0 μm and less than 1.3 μm. Thereby, generation | occurrence | production of the dent part by said resin dama can be reduced, and display quality is not impaired.

  The inventors consider such a phenomenon as follows. The uneven distribution of the resin described above is generated with the glass having a small particle size as a nucleus, and the generation of resin lumps can be suppressed by reducing the amount of the glass having a small particle size present in the paste. As a result, the recesses in the dielectric layer are reduced, and the dielectric breakdown points are also reduced. On the other hand, the small particle size glass has the effect of promoting the sintering of the glass in the firing process and promoting the formation of a denser film. As a result, the optical characteristics are deteriorated.

Next, the manufacturing method of the dielectric layer 8 of the front plate 2 in the embodiment of the present invention will be described in detail. The dielectric glass material contained in the dielectric layer 8 is mainly composed of components other than lead (Pb) -based components, and is further selected from copper oxide (CuO) and R ₂ O (R is Li, Na, K, Rb and Cs). It is comprised by the material composition containing at least 1 sort (s).

  A dielectric material powder is produced by pulverizing a dielectric material composed of these composition components with a wet jet mill or a ball mill so that the average particle diameter is 0.5 μm to 3.0 μm. Next, the dielectric material powder 35 wt% to 65 wt% and the binder component 35 wt% to 65 wt% are well kneaded with three rolls to prepare a dielectric layer paste for die coating or printing.

  As a resin component in a binder component, an acrylic resin is necessarily contained, and includes 1% by weight to 25% by weight together with ethyl cellulose. As a solvent component in the binder component, a solvent having a boiling point of less than 250 ° C. is contained in an amount of 20% to 85% by weight, and a solvent having a boiling point of 250 ° C. or more is contained in an amount of 15% to 80% by weight. Further, the solvent contained in the dielectric paste is composed of three or more types. Examples of the solvent having a boiling point of less than 250 ° C. include terpineol or butyl carbitol acetate (BCA), and examples of the solvent having a boiling point of 250 ° C. or more include phenyl diglycol (PhDG), terpinyloxyethanol (TOE), and texanol. Terpenes such as α-, β-, and γ-terpineol, ethylene glycol monoalkyl ethers, ethylene glycol dialkyl ethers, diethylene glycol monoalkyl ethers, diethylene glycol dialkyl ethers, ethylene glycol monoalkyl ether acetates, ethylene Glycol dialkyl ether acetates, diethylene glycol monoalkyl ether acetates, diethylene glycol dialkyl ether acetates, Lenglycol monoalkyl ethers, propylene glycol dialkyl ethers, propylene glycol monoalkyl ether acetates, propylene glycol dialkyl ether acetates, dipropylene glycol monoalkyl ethers, dipropylene glycol dialkyl ethers, dipropylene glycol monoalkyl ether acetate Dipropylene glycol dialkyl ether acetates, tripropylene glycol monoalkyl ethers, tripropylene glycol dialkyl ethers, tripropylene glycol trialkyl ethers, tripropylene glycol monoalkyl ether acetates, tripropylene glycol dialkyl ether acetates, Tripropylene glycol Trialkyl ether acetates, methanol, ethanol, isopropanol, may be selected as appropriate also alcohols such as such as 1-butanol.

  In the paste, dioctyl phthalate, dibutyl phthalate, triphenyl phosphate, and tributyl phosphate are added as needed, and glycerol monooleate, sorbitan sesquioleate, and homogenol (Kao Corporation) as dispersants. The printability may be improved by adding a phosphoric ester of an alkyl allyl group or the like.

  Next, using this dielectric layer paste, the front glass substrate 3 is printed by a die coating method or a screen printing method so as to cover the display electrode 6 and dried, and then the temperature is slightly higher than the softening point of the dielectric material. Bake at 575 ° C to 600 ° C.

  Regarding the PDP in the embodiment of the present invention, the inventors have performed the following evaluation. In order to be compatible with 42-inch high-definition televisions as discharge cells, the height of the barrier ribs is 0.15 mm, the interval between the barrier ribs (cell pitch) is 0.15 mm, the distance between display electrodes is 0.06 mm, and Xe is contained Twenty sets of PDPs in which an amount of 15% by volume of Ne—Xe-based mixed gas was sealed at a sealing pressure of 60 kPa were prepared, and the number of dielectric breakdown points during the lighting test was evaluated. Moreover, optical property evaluation was implemented regarding the dielectric paste from which the particle size distribution used in this evaluation differs. The evaluation results are shown in Table 1.

  The particle size distribution is measured by a laser diffraction / scattering type / particle diameter / particle size distribution measuring apparatus (Nikkiso Co., Ltd./MICROTRAC-HRA-X100).

  The optical characteristics are measured with a haze meter (manufactured by Murakami Color Research Laboratory, HM-150). In order to increase the efficiency of the PDP, it is desirable that the total light transmittance of the dielectric layer is 80% or more.

  As shown in Table 1, with respect to Samples 1 to 3 meeting the conditions of the present invention, no dielectric breakdown occurred even in the 42-inch class PDP, and the total light transmittance showed a good value. On the other hand, in Sample 4 and Sample 5, since fine powder exists in the glass component, a dent portion due to a resin dama occurs in the dielectric layer, and dielectric breakdown cannot be prevented.

  Since the effect of improving the panel brightness and reducing the discharge voltage becomes more significant as the thickness of the dielectric layer 8 is smaller, it is desirable to set the thickness as small as possible within the range where the withstand voltage does not decrease. . From the viewpoint of such conditions and visible light transmittance, in the embodiment of the present invention, the thickness of the dielectric layer 8 is set to 41 μm or less.

  Further, “substantially not containing” a lead component and a bismuth component is considered to correspond to the present invention for a dielectric layer containing a lead component or a bismuth component due to impurities or the like.

  As described above, the PDP of the present invention realizes a PDP having consideration for the environment and high reliability, and is useful for a display device having a large screen.

1 PDP
2 Front plate 3 Front glass substrate 4 Scan electrode 4a, 5a Transparent electrode 4b, 5b Metal bus electrode 5 Sustain electrode 6 Display electrode 7 Black stripe (light shielding layer)
8 Dielectric layer 9 Protective layer 10 Back plate 11 Rear glass substrate 12 Address electrode 13 Base dielectric layer 14 Partition 15 Phosphor layer 16 Discharge space

Claims (2)

Contains glass component, resin component and solvent,
The glass component does not substantially contain a bismuth component and a lead component,
The said glass component is a dielectric paste of a plasma display panel which consists of glass powder whose value of 10% cumulative particle size D10 is larger than 1.0 micrometer, and is less than 1.3 micrometers. A plasma display panel having a dielectric layer formed using the dielectric paste according to claim 1.

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