JP4613688B2 - Materials for plasma display panels - Google Patents

Description

  The present invention relates to a plasma display panel material.

  The plasma display panel is a self-luminous flat display, has excellent characteristics such as light weight and thinness, high viewing angle, etc., and can have a large screen, so it is one of the most promising display devices. It is attracting attention as one.

In general, a plasma display panel is provided with a front glass substrate and a rear glass substrate facing each other, and a large number of partition walls (also referred to as barrier ribs) are formed in the space between the substrates to separate the gas discharge portions. ing. As a material for forming the partition wall, a material in which glass powder and ceramic filler powder are mixed is widely used. This partition wall forming material needs to be able to be fired at 600 ° C. or lower in order to prevent deformation of the glass substrate. Therefore, the glass powder contains glass containing PbO, which is a component that lowers the softening point. In recent years, however, glass containing PbO has been affected by the effects on human bodies and the disposal of waste when glass powder is produced. Therefore, various partition wall forming materials for plasma display panels using ZnO—B ₂ O ₃ glass powder have been proposed. (For example, Patent Document 1)
In addition, for the purpose of improving the brightness of the plasma display panel, it is desired to employ a light-transmitting partition. Therefore, Patent Document 2 proposes a material capable of forming a light-transmitting partition. This material uses alumina powder having a specific particle size as filler powder.
JP 2002-326839 A JP 2002-110035 A

Patent Document 2 discloses that a translucent partition wall can be obtained by adding alumina powder to ZnO—B ₂ O ₃ glass powder. However, in the case of the ZnO—B ₂ O ₃ glass, the case where the technique of Patent Document 2 can be used is limited. For example, the ZnO—B ₂ O ₃ glass powder of Patent Document 2 contains a large amount of BaO, but a glass powder with a low BaO content produces a light-transmitting partition even when combined with alumina powder. Hateful.

  An object of the present invention is to provide a plasma display panel material capable of forming a partition wall having high luminance.

When the present inventors conducted various experiments, when mullite powder was used instead of alumina powder, even when ZnO—B ₂ O ₃ glass powder having a low BaO content was used, a light-transmitting partition wall It became clear that can be formed. This is presumably because this kind of ZnO—B ₂ O ₃ glass tends to have a refractive index closer to that of mullite than alumina. However, the obtained partition wall had a deep beige color tone, and even when it had translucency, it was difficult to produce a plasma display panel with high brightness. As a result of further investigations by the present inventors, it has been found that the above-mentioned problems can be solved by pre-calcining mullite powder, and is proposed as the present invention.

That is, a plasma display panel for material of the present invention comprises a glass powder and filler powder, Ri least some gum light powder der of the filler powder, the mullite powder mullite powder subjected to calcination before use It is characterized by being.

  The mullite powder is preferably fired at 600 to 1100 ° C.

  The 50% average particle size of the mullite powder is preferably 0.5 to 6 μm.

The glass powder is preferably made of ZnO—B ₂ O ₃ glass powder, particularly ZnO—B ₂ O ₃ lead-free glass. More specifically, the ZnO—B ₂ O ₃ glass powder is in mass percentage, ZnO 20-60%, B ₂ O ₃ 15-50%, BaO 0-25%, SiO ₂ 1-25%, Li ₂ O + Na. Glass containing ₂ O + K ₂ O 0-17%, in particular by mass percentage, ZnO 30-60%, B ₂ O ₃ 15-35%, BaO 0-25%, SiO ₂ 3-20%, Li ₂ O 0. Examples include BaO—ZnO—B ₂ O ₃ -based glass containing _{2 to} 6% and Li ₂ O + Na ₂ O + K ₂ O 1 to 12%.

  Moreover, it is preferable that the material of this invention contains 60-90 mass% of glass powder and 10-40 mass% of filler powder, and it is desirable for the mullite powder which baked 20-100 mass% of filler powder to occupy.

  In addition, the plasma display panel paste and the green sheet of the present invention are characterized by including the above-mentioned materials.

  Moreover, the partition of this invention is formed using the said material, a paste, or a green sheet, It is characterized by the above-mentioned.

  Although the plasma display panel material of the present invention uses mullite powder as a filler, it is possible to produce a plasma display panel with high whiteness and high brightness of the partition walls obtained. Furthermore, since mullite powder has high mechanical strength and relatively low dielectric constant, the material of the present invention is advantageous in forming a partition having a low dielectric constant.

Further, when used in combination with ZnO—B ₂ O ₃ glass powder, a light-transmitting partition wall can be formed, and a plasma display panel with higher brightness can be manufactured. In addition, since both materials have low dielectric constants, partition walls having a low dielectric constant (ε10 or less) can be formed, and it becomes easy to produce a panel with low power consumption.

  Hereinafter, the material of the present invention will be described in detail.

  The material for a plasma display panel of the present invention mainly uses mullite powder as a filler powder. As the mullite powder, either an alumina and silica fired product or an electromelted product can be used.

  By the way, the mullite powder decreases in whiteness as the particle size of the powder decreases, and colors the partition walls. This seems to be due to foreign matters contained in the mullite powder and structural defects of the crystal. Therefore, in the present invention, mullite powder fired in advance is used. If the mullite powder is baked in advance, foreign matters are removed and defects are improved, so that a mullite powder with high whiteness is obtained.

  The mullite powder used in advance is used. The firing temperature is preferably in the range of 600 to 1100 ° C. When fired at a temperature lower than 600 ° C., a white appearance is difficult to obtain. Firing at a temperature higher than 1100 ° C. is not preferable because sintering of the mullite powder proceeds and the particle size easily changes. As the firing furnace, any of a resistance heating type, induction heating type, plasma heating type electric furnace, and a firing furnace using a fuel such as liquid or gas can be used. In addition, any of batch and continuous operation methods can be applied.

  In the present invention, all of the filler powder may be mullite powder, but other filler powders may be used in combination as long as the object of the present invention is not impaired. For example, a ceramic filler such as alumina or silica can be introduced for adjusting the thermal expansion coefficient. Further, for the purpose of improving the shape maintaining property, in addition to alumina and silica, a ceramic filler other than mullite such as cordierite may be introduced. The ratio of the mullite powder to the whole filler powder is 20 to 100% by mass, preferably 25 to 100% by mass, and more preferably 30 to 100% by mass. When the proportion of the mullite powder is small, the translucency of the obtained partition wall is lowered.

  The mullite powder preferably has a 50% average particle size of 0.5 to 6 μm, particularly 0.6 to 5 μm. If the average particle size of the mullite powder is too small, rheology adjustment becomes difficult in the process of being supplied in the form of a paste, and the cost becomes high. On the other hand, when the average particle size is increased, the shape maintainability tends to be deteriorated. Two or more kinds of mullite having different average particle diameters can be mixed and used at an arbitrary mixing ratio. For filler powders other than mullite, it is desirable to use those having a 50% average particle diameter in the range of 0.5 to 6 μm for the same reason as in the case of mullite. However, when titania is used, the translucency of the partition wall is remarkably impaired, so it should not be used in the present invention.

The plasma display panel material of the present invention can use various materials as glass powder. For example, PbO—B ₂ O ₃ glass powder, ZnO—B ₂ O ₃ glass powder, Bi ₂ O ₃ —B ₂ O ₃ glass powder, etc., any glass powder that can be used for partition walls can be used without any problem. Is possible.

In particular, when combined with ZnO—B ₂ O ₃ glass powder, a light-transmitting partition wall can be produced. The ZnO—B ₂ O ₃ glass is a glass containing, for example, 30% by mass or more of ZnO and 15% by mass or more of B ₂ O ₃ . Moreover, it is preferable that it is glass of the composition which does not contain BaO or does not exceed 25 mass% even when it contains. The reason for this is that glass in this range is more advantageous in producing a partition wall having excellent translucency when combined with mullite powder than alumina powder. Further, for the purpose of reducing PbO from the partition wall material, it is desired that PbO is 1% by mass or less, preferably not contained at all.

Preferred exemplary compositions of ZnO-B ₂ O ₃ based glass, in percent by _{mass, 20~60% ZnO, B 2 O} 3 15~50%, BaO 0~25%, SiO 2 1~25%, Li 2 O + Na Glass containing ₂ O + K ₂ O 0-17%, in particular by mass percentage, ZnO 30-60%, B ₂ O ₃ 15-35%, BaO 0-25%, SiO ₂ 3-20%, Li ₂ O 0. Examples include ZnO—B ₂ O ₃ -based glass containing _{2 to} 6% and Li ₂ O + Na ₂ O + K ₂ O 1 to 12%. The glass having the above composition can produce a partition wall material that can be fired at a low temperature of 600 ° C. or less, particularly about 560 ° C. Each component will be described below.

  ZnO is a component that lowers the thermal expansion coefficient while lowering the softening point, and its content is 20 to 60%, preferably 30 to 60%, more preferably 35 to 55%, and further preferably 37 to 54%. is there. When the ZnO content is less than 20%, it is difficult to obtain the above effect. When the ZnO content is more than 60%, crystals are precipitated in the glass and a dense sintered body cannot be obtained.

B ₂ O ₃ is a component constituting the skeleton of the glass, and its content is 15 to 50%, preferably 15 to 35%, more preferably 16 to 33%. If B ₂ O ₃ is less than 15%, vitrification becomes difficult. On the other hand, if B ₂ O ₃ is more than 50%, the softening point becomes high, and if it is fired at a temperature of 560 ° C. or less, it becomes difficult to obtain a dense sintered body and the panel characteristics may be deteriorated.

  BaO is a component that stabilizes the glass, and its content is 0 to 25%, preferably 3 to 25%, particularly preferably 5 to 20%. BaO is not an essential component, but if it is less than 3%, the glass becomes unstable and tends to crystallize, causing problems with the adhesion to the dry film, and crystals are precipitated during firing to obtain a dense sintered body. It may become impossible. On the other hand, if it exceeds 25%, the coefficient of thermal expansion becomes high and it becomes incompatible with that of the glass substrate, or the translucency is lowered.

SiO ₂ is a component that forms a glass skeleton, and its content is 1 to 25%, preferably 3 to 20%, more preferably 4 to 17%, and still more preferably 4 to 16%. If the SiO ₂ content is less than 1%, the glass becomes unstable. If the SiO ₂ content is more than 25%, the softening point becomes high and it becomes difficult to fire at a temperature of 560 ° C. or less.

The alkali component needs to be 0 to 17%, preferably 1 to 12%, more preferably 2 to 10% in terms of the total content of Li ₂ O, Na ₂ O and K ₂ O. By containing 1% or more in the total amount, the softening point of the glass is easily lowered, and firing at a temperature of 560 ° C. or less is facilitated. On the other hand, if it exceeds 17%, the glass becomes unstable and tends to crystallize, resulting in a decrease in adhesion to the dry film and a problem in durability of the glass.

Among the alkali components, Li ₂ O is a component that significantly lowers the softening point of the glass, preferably 0.2 to 6%, more preferably 0.5 to 5%. If the Li ₂ O content is less than 0.2%, the softening point is difficult to lower, and it is difficult to fire at a temperature of 560 ° C. or lower. On the other hand, if Li ₂ O is more than 6%, the glass becomes extremely unstable and easily crystallized, the adhesion to the dry film is reduced, or crystals are precipitated during firing to obtain a dense sintered body. Disappear.

For the purpose of maintaining the stability of the glass, when it is not possible to add more in the glass of Li ₂ O, as with Li ₂ O is a component to lower the softening point of the glass Na ₂ O or K ₂ O, or both It is desirable to use together. However, if the content of Na ₂ O and K ₂ O is increased, the stability of the glass is lowered, and there is a concern that the adhesiveness with the dry film may be reduced and a dense fired body may not be obtained. It is desirable to limit Na ₂ O to 9% or less, 8% or less, particularly 6% or less, and K ₂ O to 6% or less, particularly 5% or less.

When an alkali metal component is added, the adhesion to the dry film tends to be lowered. Therefore, Al ₂ O ₃ may be contained in order to improve adhesion. However, as the Al ₂ O ₃ content increases, the softening point increases, so it is desirable to limit it to 1.5% or less.

Further, in order to stabilize the glass, it is desirable that the ratio of _{BaO / (B 2 O 3 +} SiO 2) in the range of 0.1 to 0.8. If this ratio is less than 0.1, the glass becomes unstable and crystals are likely to precipitate during firing, making it difficult to form a dense sintered body. On the other hand, if it is larger than 0.8, the thermal expansion coefficient of the material becomes high and it becomes difficult to match that of the glass substrate. A more preferable range is 0.15 to 0.6.

In addition to the above components, other components can be added as long as the effects of the present invention are not impaired. For example, in order to improve water resistance and chemical resistance, alkaline earth metal oxides such as MgO, CaO and SrO, Ta ₂ O ₅ , La ₂ O ₃ , SnO ₂ , ZrO ₂ , TiO ₂ and Nb ₂ O _{5 are used.} And P ₂ O ₅ may be added for glass stabilization. The total amount of these components should be limited to 12% or less, preferably 10% or less.

  In the material of the present invention, the ratio of the glass powder to the filler powder is 60 to 90% by weight of glass powder, 10 to 40% by weight of filler powder, preferably 60 to 85% by weight of glass powder, 15 to 40% by weight of filler powder, Preferably they are 63-84 mass% of glass powder, and 16-37 mass% of filler powder. When there is little filler powder (that is, there are many glass powders), shape maintainability will fall. On the other hand, when the filler powder increases (that is, when the glass powder is small), the sinterability tends to be insufficient, and it becomes difficult to form a dense partition. Moreover, the translucency of the partition obtained is reduced.

  The material for a plasma display panel of the present invention can be used in the form of a paste or a green sheet.

  When used in the form of a paste, a thermoplastic resin, a plasticizer, a solvent and the like are used together with the above-described materials. As content in the paste of forming materials, such as a partition, about 30-90 mass% is common. The viscosity of the paste is preferably 200 to 1500 poise. If it is 200 poise or less, there is a problem in the storage property of the paste, and if it is 1500 poise or more, a problem occurs in printability. Further, when the paste viscosity is provided in a state of 1000 poise or less, it is desirable to add up to 3% of an antioxidant or a surfactant in order to prevent paste separation, viscosity reduction, resin degradation, etc. . In addition, the viscosity as used in the field of this invention is a value when it measures on conditions of 23 degreeC and shear rate 5.7 / sec.

  The thermoplastic resin is a component that increases the film strength after drying and imparts flexibility, and the content is generally about 0.1 to 20% by mass. As the thermoplastic resin, polybutyl methacrylate, polyvinyl butyral, polymethyl methacrylate, polyethyl methacrylate, ethyl cellulose and the like can be used, and these are used alone or in combination.

  The plasticizer is a component that controls the drying speed and imparts flexibility to the dry film, and the content thereof is generally about 0 to 10% by mass. As the plasticizer, butylbenzyl phthalate, dioctyl phthalate, diisooctyl phthalate, dicapryl phthalate, dibutyl phthalate and the like can be used, and these are used alone or in combination.

  The solvent is a material for pasting the material, and its content is generally about 10 to 30% by mass. As the solvent, for example, terpineol, diethylene glycol monobutyl ether acetate, 2,2,4-trimethyl-1,3-pentadiol monoisobutyrate or the like can be used alone or in combination.

  The paste can be prepared by preparing forming materials such as partition walls (glass powder and filler powder), a thermoplastic resin, a plasticizer, a solvent, and the like, and kneading them at a predetermined ratio.

  For example, in order to form partition walls using such a paste, these pastes are first applied using a screen printing method or a batch coating method, and then unnecessary portions are removed using a sand blast method. Baking is performed to obtain a partition having a predetermined shape.

  When the plasma display panel material of the present invention is used in the form of a green sheet, a thermoplastic resin, a plasticizer, or the like is used together with the forming material such as the partition wall.

  The content of the forming material such as the partition walls in the green sheet is generally about 60 to 80% by mass.

  As the thermoplastic resin and the plasticizer, the same thermoplastic resin and plasticizer used in the preparation of the paste can be used, and the mixing ratio of the thermoplastic resin is about 5 to 30% by mass. Generally, the mixing ratio of the plasticizer is generally about 0 to 10% by mass.

  As a general method of producing a green sheet, a forming material such as a partition wall, a thermoplastic resin and a plasticizer are prepared, and a main solvent such as toluene and an auxiliary solvent such as isopropyl alcohol are added thereto. A slurry is formed, and this slurry is formed into a sheet on a film of polyethylene terephthalate (PET) or the like by a doctor blade method. After forming the sheet, the solvent and the solvent can be removed by drying to obtain a green sheet.

  A glass layer can be formed by thermocompression-bonding the green sheet obtained as described above to a portion where a glass layer is to be formed, and then firing it. In the case of forming the partition, after forming the coating layer by thermocompression, it is processed into a predetermined partition shape in the same manner as in the case of the paste described above.

  In the above description, the sandblasting method using paste or green sheet is described as an example of the partition wall forming method, but the method is not limited to these methods, and is not limited to the printing lamination method, lift-off method, photosensitivity. It is a material that can be applied to other forming methods such as a paste method, a photosensitive green sheet method, and a press molding method.

The partition walls of the plasma display panel manufactured as described above exhibit a white color tone. As a parameter for evaluating whiteness, an L ^* value measured with a color difference meter can be used. Specifically, the L ^* value obtained by press-molding the partition wall forming material to form a powder molded body and measuring the surface of the fired body with a color difference meter is used. In the present invention, the L ^* value is preferably 60% or more, particularly 65% or more, and more preferably 70% or more.

  When a light-transmitting partition wall is produced, as a parameter for evaluating the light-transmitting property, after baking for 10 minutes at the softening point of the glass powder, a diffuse transmittance value of 550 nm in terms of 30 μm is used. Can do. In the present invention, this value is desirably 50% or more, particularly 55% or more. If the diffuse transmittance value is 50% or more, an improvement in the brightness of the plasma display panel can be expected.

  Note that the material of the present invention can be used for purposes other than partition walls, and can be used for dielectrics for protecting address electrodes, for example.

  Hereinafter, the present invention will be described in detail based on examples. However, the present invention is not limited to the following examples.

  Table 1 shows the glass powder composition (samples A to F) used in this example, and Tables 2 and 3 show the filler powder (samples a to h) used in this example. Tables 4 to 6 show examples of the partition wall material (sample Nos. 1 to 22) and their evaluation results.

Each sample in Table 1 was prepared as follows. First, glass materials such as various oxides and carbonates were prepared so as to have the composition shown in the table, mixed uniformly, and then placed in a platinum crucible and melted at 1250 ° C. for 2 hours to obtain a uniform glass body. This was then pulverized with an alumina ball mill to obtain a glass powder having an average particle size of 3 μm and a maximum particle size of 20 μm. The thermal expansion coefficient and softening point of the obtained glass powder were measured. As a result, each of the samples A to E had a thermal expansion coefficient of 69.3 to 80.0 × 10 ⁻⁷ / ° C. and a softening point of 564 ° C. or less.

  Moreover, the filler powder of Tables 2 and 3 was prepared. In particular, the mullite powders of Samples a to e were fired before use. Further, when the particle size was confirmed after firing, it was confirmed that the sample d had a particle size change. This seems to have been due to the progress of sintering.

  Next, partition wall materials were prepared using the glass powder of Table 1 and the filler powders of Tables 2 and 3.

  First, each glass powder and various ceramic filler powders were mixed so that the blending ratios shown in Tables 4 to 7 were obtained. In addition, the mixture ratio shown to a table | surface is shown by the weight% display. Next, the obtained mixture was kneaded with a terpineol solution of ethyl cellulose to obtain a partition wall forming paste.

Using this paste, shape maintenance, transmittance, and film thickness were evaluated. Moreover, L ^* value was evaluated using the mixed powder which consists of glass powder and filler powder. The results are shown in the table.

  The shape maintainability was evaluated as follows. First, two pieces of window glass (plate thickness 1.7 mm) were prepared, and a coating layer having a thickness of 200 μm was formed on each glass plate by a screen printing method. Next, a dry film resist (DFR) was laminated on the coating layer. Subsequently, using this resist as a mask, a portion not covered with the resist was removed by a sandblasting method to form a partition wall shape. Next, one was fired at a softening point of the glass powder and the other was fired for 10 minutes at a temperature 20 ° C. higher than the softening point of the glass powder. The height, H (softening point), and H (softening point + 20 ° C.) of the two types of partition walls thus formed were evaluated, and the change rate ΔH was obtained by the following calculation formula. The shape maintenance property as a material was evaluated. The height of the partition was obtained from the photograph of the cross section of the partition observed by SEM.

ΔH = (H (softening point + 20 ° C.) / H (softening point)) × 100
The transmittance and film thickness were evaluated as follows. First, a coating layer of about 50 μm is formed on a window glass (plate thickness 1.7 mm) in the same manner as described above so that the fired film thickness becomes 30 ± 1 μm, and fired for 10 minutes at the softening point of the glass powder. Thus, a fired film was produced. The diffusion transmittance at 550 nm was measured for the barrier ribs thus produced. Furthermore, this value was converted into a film thickness of 30 μm and described as transmittance. The diffuse transmittance was measured with a spectrophotometer UV-3100 manufactured by Shimadzu under a detector with an integrating sphere, and the value including the glass substrate was measured. The film thickness of each sample is a value evaluated with respect to the film thickness after firing, and was measured with a micrometer.

The L ^* value was evaluated as follows. First, a partition wall forming material in which each glass powder and various ceramic filler powders are mixed so as to have the blending ratios shown in Tables 4 to 6 is weighed for each density, and pressed with a mold having an inner diameter of 20 mm to obtain a powder. A molded body was produced. Subsequently, the molded body was fired at the firing temperature in the table, and then the surface of the obtained sintered body was subjected to a reflection method using a color difference meter JS-555 manufactured by Color Techno System Co., Ltd. with a D65 light source ^. a ^* b ^* colorimetry was performed, and the L ^* value obtained at this time was used.

Claims (13)

Comprises glass powder and filler powder, wherein at least a portion gum light powder der filler powder is, the mullite powder plasma display panel material, characterized in that the mullite powder having been subjected to firing treatment before use. The material for a plasma display panel according to claim 1, wherein the mullite powder is fired at 600 to 1100 ° C. The material for a plasma display panel according to claim 1, wherein the glass powder is made of ZnO-B ₂ O ₃ glass powder. _ZnO-B 2 _{O 3} based glass powder, a plasma display panel for material according to claim 3, characterized in that it consists of _ZnO-B 2 _{O 3} based lead-free glass. _ZnO-B 2 _{O 3} based glass powder, by mass _{percentage, 20~60% ZnO, B 2 O} 3 15~50%, BaO 0~25%, SiO 2 1~25%, Li 2 O + Na 2 O + K 2 O The material for a plasma display panel according to claim 3 , wherein the material comprises 0 to 17% glass. _ZnO-B 2 _{O 3} based glass powder, by mass _{percentage, 30~60% ZnO, B 2 O} 3 15~35%, BaO 0~25%, SiO 2 3~20%, Li 2 O 0.2~ _{6%, Li 2 O + Na} 2 O + K 2 O 1~12% plasma display panel material according to claim 3, characterized in that it consists of glass containing. The material for a plasma display panel according to claim 1, comprising 60 to 90% by mass of glass powder and 10 to 40% by mass of filler powder. The material for a plasma display panel according to claim 1, wherein the baked mullite powder accounts for 20 to 100% by mass of the filler powder. PDP paste characterized by containing any of the materials of claims 1-8. PDP green sheet characterized by comprising any of the material of claims 1-8. A partition wall for a plasma display panel, which is formed using the material according to any one of claims 1 to 8 . A partition of a plasma display panel formed by using the paste according to claim 9 . A partition of a plasma display panel formed using the green sheet of claim 10 .