JP2011165487A - Paste for plasma display panel dielectric layer, plasma display panel using the paste, and manufacturing method of plasma display panel using the paste - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve a PDP which secures high reliability and high quality image although having a high definition display, and can reduce the amount of use of a plasticizer such a harmful substance as DBP. <P>SOLUTION: The paste for dielectric layer is used for a PDP in which an electrode and a dielectric layer are formed on at least one of substrates. The paste contains a glass material and a resin component, and the content of acrylic resin contained in the paste in terms of a weight fraction is 5 wt.% or more and 20 wt.% or less against the total amount of the paste, and the content of plasticizer contained in the paste in terms of a volume fraction is 1.0 vol.% or less against the glass material. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a plasma display panel used for a display device or 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 is doing.

  A silver electrode for ensuring conductivity is used for the bus electrode of the display electrode, and a low melting point glass mainly composed of lead oxide is used for the dielectric layer. In these methods, a paste composed of components such as a binder resin, a plasticizer, and a solvent is applied using a screen printing method, a die coating method, and the like, dried, and then fired at about 450 ° C. to 600 ° C. Yes. And the example which does not contain a lead component as a dielectric material layer from the consideration to the environmental problem in recent years is disclosed (for example, refer patent document 1 etc.).

JP 2003-128430 A

  In recent years, with the progress of science and technology and the diversification of lifestyles, there are many kinds of chemical substances that are produced and used, and are used in every scene of life. However, many of these chemicals are concerned about harmful effects on human health and ecosystems. Among them, plasticizers such as dibutyl phthalate (hereinafter referred to as DBP) are highly harmful substances such as suspected teratogenicity and endocrine disruption. ing. On the other hand, as the name suggests, plasticizers such as DBP are currently added to a wide variety of materials due to the feature that they can be processed easily by imparting flexibility to the material.

  On the other hand, PDP has been applied to high-definition televisions having more than twice the number of scanning lines as compared with the conventional NTSC system. By such high definition, the number of scanning lines is increased and the number of display electrodes is increased. Increases, and the distance between the display electrodes decreases. For this reason, the dielectric layer covering the display electrodes also needs to be formed without any gaps in the display electrode intervals that have become smaller. If there is a gap or the like, the dielectric strength characteristics required for the dielectric layer will deteriorate. Therefore, conventionally, in order to form such a dielectric layer, a dielectric layer without voids is formed by forming the dielectric layer by using a screen printing method or a die coating method using the paste containing the plasticizer described above. .

  However, as mentioned above, plasticizers such as dibutyl phthalate are highly harmful substances such as suspected teratogenicity and endocrine disruption, and it is highly desirable to reduce the amount used and not use them.

The present invention solves the above-described problems and ensures high reliability even in high-definition display.
The object is to reduce the amount of plasticizers such as DBP, which are harmful substances, while realizing DP.

  In order to solve the above problems, the paste of the present invention is a dielectric layer paste used for a PDP in which an electrode and a dielectric layer are formed on at least one substrate, and the paste is made of a glass material and a resin component. The content expressed by the weight fraction of the acrylic resin contained in the paste is 5% by weight or more and 20% by weight or less with respect to the total amount of the paste, and is represented by the volume fraction of the plasticizer contained in the paste. Content is 1.0 volume% or less with respect to glass material, It is characterized by the above-mentioned. The PDP of the present invention is a PDP in which an electrode and a dielectric layer are formed on at least one substrate, wherein the dielectric layer is formed using the dielectric layer paste. Furthermore, it is a method of manufacturing a PDP having a step of forming an electrode and a dielectric layer on at least one substrate, and the coating step using the dielectric paste is performed only once in the step of forming the dielectric layer. It is characterized by being.

  As described above, an object of the present invention is to reduce the amount of plasticizers such as DBP, which are harmful substances, while realizing a PDP that ensures high reliability and high quality image quality even for high-definition display. And

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), tin oxide (SnO ₂ ), etc., and metal bus electrodes 4b and 5b formed on transparent electrodes 4a and 5a, respectively. 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 also 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 a discharge space is obtained. 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. Conventionally, as a method of forming a dielectric layer, a paste composed of a dielectric glass powder component (hereinafter referred to as a dielectric glass material) and components such as a binder resin, a plasticizer, and a solvent is screen printed or die coated. Using a method such as coating on the substrate on which the electrode is formed, drying and baking at about 450 ° C. to 600 ° C., or applying the dielectric paste on the film and drying to transfer it onto the substrate on which the electrode is formed In addition, a dry film method in which baking is performed at about 450 ° C. to 600 ° C. is known.

  However, the dry film method is not preferable in terms of high production costs and environmental problems as described above. Further, in the screen printing method or die coating method using a dielectric paste, it is necessary to cover the display electrode 6 without a gap in order to ensure high voltage resistance of the dielectric layer, and conventionally a method of applying and baking the paste multiple times Has been taken. For this reason, many production facilities are required, and further, the cost is increased due to an increase in energy consumption during production.

  That is, in order to form the dielectric layer 8 at a low cost, it is necessary to form the dielectric layer 8 having a high withstand voltage while using a dielectric paste only once. When the coating process is performed only once using the dielectric paste, the following problem occurs.

  When silver is contained in the component of the display electrode 6, diffusion of silver ions to the dielectric layer 8 and the front glass substrate 3 occurs. The diffusion of silver ions is reduced by alkali metal ions in the dielectric layer 8 and divalent tin ions contained in the front glass substrate 3 to form silver colloids.

  As a result, not only the yellowing phenomenon that the dielectric layer and the glass substrate are strongly colored yellow or brown, but also the presence of silver colloid leads to a decrease in the dielectric strength of the dielectric layer 8.

  In forming the dielectric layer 8, it has been found that such a phenomenon appears more remarkably when the dielectric paste is used and the coating process is performed only once. In particular, with the recent shift to high-definition, the number of scanning lines increases, the number of display electrodes increases, and the distance between display electrodes decreases. Therefore, the yellowing phenomenon and the dielectric layer dielectric withstand voltage drop become remarkable, the image quality is remarkably impaired, and the production yield is lowered by the insulation failure of the dielectric layer 8.

  In contrast, the prior art discloses an example in which yellowing is alleviated by reducing the amount of plasticizer in the dielectric paste. However, as a result of investigations by the inventors, when the plasticizer contained in the dielectric paste is reduced to 1.0% by volume or less with respect to the dielectric glass material, 50% of the dry film is obtained by drying the dielectric paste. It has been found that minute cracks of about ˜500 μm are likely to occur, and this crack causes dielectric breakdown of the dielectric layer 8 after firing, resulting in deterioration of the dielectric strength of the dielectric layer 8.

  On the other hand, with respect to the dielectric paste of the dielectric layer 8, the acrylic resin contained in the dielectric paste is set to 5% by weight or more and 20% by weight or less with respect to the total amount of the paste. It has been found that even when the content is 0% or less, minute cracks are not generated in the dried film obtained by drying the dielectric paste. This is because the dry film itself using acrylic resin is plastic.

  Here, when the content of the acrylic resin is lower than 5% by weight with respect to the total amount of the paste, sufficient plasticity cannot be obtained, and minute cracks of about 50 to 500 μm are easily formed in the dry film. Also, if the content is greater than 20% by weight, the resin component remains in the dielectric layer even after the subsequent firing step, resulting in an increase in residual gas brought into the PDP discharge space, resulting in an image. The display state is deteriorated, which is not preferable.

  As described above, in the embodiment of the present invention, with respect to the dielectric paste of the dielectric layer 8, the acrylic resin contained in the dielectric paste is 5% by weight or more and 20% by weight or less in terms of the weight fraction with respect to the total amount of paste, and The plasticizer contained in the dielectric paste is 1.0 volume% or less in terms of the volume fraction with respect to the dielectric glass material. As a result, the dielectric layer 8 is formed at a low cost, while maintaining a high withstand voltage, realizing a PDP with excellent display quality free from defects of the light emitting pixels, and using a plasticizer such as DBP which is a harmful substance The amount can be reduced.

Next, the manufacturing method of the dielectric layer 8 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).

  The dielectric material composed of these composition components is pulverized by a wet jet mill or a ball mill so that the average particle diameter is 0.5 μm to 3.0 μm, and a dielectric glass material powder is produced. Next, 35% to 65% by weight of the powder of the dielectric glass material, 35% to 65% by weight of the binder component, and 1.0% by volume or less of the plasticizer based on the volume fraction of the dielectric glass material, A dielectric layer paste for die coating or printing is prepared by kneading well with three rolls.

  The binder component is a solvent containing ethyl cellulose or acrylic resin. However, the acrylic resin is 5% by weight to 20% by weight with respect to the total amount of paste. Further, as a dispersant, glycerol monooleate, sorbitan sesquioleate, homogenol (a product name of Kao Corporation), phosphate ester of alkylallyl group, or the like may be added to improve printability.

  The solvent component is terpineol or butyl carbitol acetate, but terpenes such as α-, β-, γ-terpineol, ethylene glycol monoalkyl ethers, ethylene glycol dialkyl ethers, diethylene glycol monoalkyl ethers, diethylene glycol dialkyl ether. , Ethylene glycol monoalkyl ether acetates, ethylene glycol dialkyl ether acetates, diethylene glycol monoalkyl ether acetates, diethylene glycol dialkyl ether acetates, propylene glycol monoalkyl ethers, propylene glycol dialkyl ethers, propylene glycol monoalkyl ether acetates , Propylene glycol dialki Ether acetates, dipropylene glycol monoalkyl ethers, dipropylene glycol dialkyl ethers, dipropylene glycol monoalkyl ether acetates, 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, alcohols such as methanol, ethanol, isopropanol, 1-butanol, etc. It can be selected as appropriate.

  Moreover, although dibutyl phthalate is used as the plasticizer, dioctyl phthalate, triphenyl phosphate, tributyl phosphate and the like can be selected as appropriate. If necessary, glycerol monooleate, sorbitan sesquioleate, homogenol (product name of Kao Corporation), phosphate ester of alkylallyl group, or the like may be added as a dispersant to improve printability.

  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.

  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.

(Example)
As the PDP 1 in the embodiment of the present invention, the height of the barrier ribs 14 is 0.15 mm, the interval of the barrier ribs (cell pitch) is 0.15 mm, and the electrodes of the display electrodes 6 so that the discharge cells are adapted to a high-definition television of 42 inch class. A PDP1 in which a distance between the electrodes is 0.06 mm and the electrode film thickness is 6.0 μm and a Ne—Xe mixed gas having a Xe content of 15% and a volume fraction of 15% is enclosed in an enclosure pressure of 60 kPa is produced. The performance was evaluated.

  Table 1 shows the plasticizer content, ethylcellulose content, and acrylic resin content of the dielectric pastes that were studied. And the measurement result of the crack number of the dry film produced using the paste is shown. Dielectric pastes shown in the same table were produced, and PDPs having these dielectric layers 8 were produced.

  The plasticizer content, ethylcellulose content, and acrylic resin content described in Table 1 are as described above, and the plasticizer content is the volume fraction of the dielectric glass material, ethylcellulose. Content and acrylic resin content are weight fractions with respect to the total amount of paste. Then, in order to evaluate the characteristics of the PDP composed of the dielectric paste shown in Table 1, as an index for degrading the dielectric strength, there is a minute amount present on the surface of the dielectric layer of the front plate on which the dielectric layer is formed. The number of cracks was measured. The evaluation results are also shown in Table 1.

  As shown in the table, in the comparative example, the plasticizer is 0.9% by volume, but since the acrylic resin is not included, two micro cracks are generated, which is not preferable. On the other hand, since no plasticizer is contained in the examples and 8.8% by weight of the acrylic resin is contained, generation of microcracks is not observed.

  As described above, the PDP of the present invention is a PDP in which an electrode and a dielectric layer are formed on at least one substrate, and the dielectric layer is formed using the dielectric paste, and the acrylic contained in the dielectric paste. The resin is characterized by containing 5% by weight or more and 20% by weight or less of a weight fraction with respect to the total amount of the paste, and containing a plasticizer contained in the dielectric paste by 1.0% by volume or less with respect to the dielectric glass material. To do. By adopting such a configuration, it is possible to reduce the amount of plasticizers such as DBP, which are harmful substances, while realizing a PDP that ensures high reliability and high quality image quality even in high-definition display. I can do it.

  In addition, the numerical value of the content of each material composition described above has a measurement error of about ± 0.05% for dielectric materials, and a measurement error of about ± 0.1% for dielectric layers after firing. To do. The same effects as those of the present invention can be obtained even in a material composition with a content in a numerical range including these errors. 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 present invention reduces the amount of plasticizers such as DBP, which are harmful substances, while realizing a PDP that ensures high reliability and high-quality image quality even for high-definition display. It is useful in that it can.

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 (3)

A dielectric layer paste used in a plasma display panel in which an electrode and a dielectric layer are formed on at least one substrate, the paste including a glass material and a resin component, and a weight of an acrylic resin included in the paste The content expressed as a fraction is 5% by weight or more and 20% by weight or less with respect to the total amount of the paste, and the content expressed as a volume fraction of a plasticizer contained in the paste is based on the glass material. 1.0% by volume or less, a dielectric layer paste used for a plasma display panel. A plasma display panel in which an electrode and a dielectric layer are formed on at least one substrate, wherein the dielectric layer is formed using the dielectric layer paste according to claim 1. Plasma display panel. A method of manufacturing a plasma display panel comprising a step of forming an electrode and a dielectric layer on at least one substrate, wherein the coating step using the dielectric paste is performed once in the step of forming the dielectric layer. A method for producing a plasma display panel, comprising:

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