JP2005317247A - Dielectric structure of plasma display panel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dielectric structure of a plasma display panel capable of obtaining a dielectric layer having excellent transparency and a high withstand voltage, wherein yellowing is hardly caused by reaction with a silver electrode. <P>SOLUTION: This dielectric structure of a plasma display panel includes a lower dielectric layer covering an electrode, and an upper dielectric layer formed on the lower dielectric layer, and is characterized by that the lower dielectric layer and the upper dielectric layer are formed of glass; and the upper dielectric layer is formed of glass having a softening point in the range of 545-600°C. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a dielectric structure of a plasma display panel.

  In the plasma display panel, a transparent dielectric layer having a film thickness of 30 to 40 μm is formed on a scan electrode for plasma discharge formed on a front glass plate in order to maintain discharge. Silver is widely used for the scanning electrode. The dielectric layer is required to have excellent transparency and high withstand voltage, but these characteristics are the reactivity between the dielectric and the electrode, the surface smoothness of the dielectric layer, and the state of bubbles in the layer. Depends greatly on

Conventionally, as a method of forming such a dielectric layer, a paste-like dielectric forming material prepared by kneading a powder component such as glass powder and a vehicle (a solution obtained by dissolving a thermoplastic resin in a solvent) is screen-printed. Thus, a firing method is known.
JP 11-162355 A

  However, in the conventional dielectric material, the silver electrode and glass react to cause a phenomenon that the dielectric layer is colored yellow (yellowing), resulting in a decrease in transmittance. If the dielectric layer is formed at a low temperature in order to prevent yellowing, it is difficult to form a coating layer having a smooth and uniform film thickness, and many bubbles remain. As a result, there arises a problem that it is difficult to form a dielectric layer having high transparency and high withstand voltage.

  Therefore, by suppressing the reaction with the silver electrode by forming a two-layered dielectric layer using a high softening point glass that does not easily react with the silver electrode as the lower dielectric layer and a low softening point glass as the upper dielectric layer, At the same time, the surface smoothness is improved (for example, Patent Document 1).

  However, even in this method, a dielectric layer having a sufficiently high transparency and withstand voltage has not been obtained yet.

  An object of the present invention is to provide a dielectric structure of a plasma display panel that is less susceptible to yellowing due to a reaction with a silver electrode, has excellent transparency, and can obtain a dielectric layer having a high withstand voltage.

  As a result of various verifications by the present inventors, the upper dielectric material that has been used in the past generates many bubbles during firing, and the upper dielectric is fired at a temperature considerably higher than the softening point. It has been found that the generated bubbles grow into large bubbles, and the present invention has been proposed.

  That is, the dielectric structure of the plasma display panel of the present invention is a dielectric structure of a plasma display panel having a lower dielectric layer covering the electrodes and an upper dielectric layer formed on the lower dielectric layer. The lower dielectric layer and the upper dielectric layer are made of glass, and the upper dielectric layer is made of glass having a softening point of 545 to 600 ° C.

The upper dielectric layer is composed of PbO 25-55%, B ₂ O ₃ 10-40%, SiO ₂ 1-15%, BaO 5-30%, ZnO 3-35%, Al ₂ O ₃ 0 by mass percentage. It consists of glass containing 10 to 10%, CaO + MgO + SrO + Bi ₂ O ₃ 0 to 20%, TiO ₂ + ZrO ₂ + SnO ₂ 0 to 10%.

The upper dielectric layer is composed of ZnO 15-55%, B ₂ O ₃ 26-60%, SiO ₂ 0-30%, Al ₂ O ₃ 0-10%, K ₂ O 3-20% by mass percentage, It consists of a glass containing Li ₂ O + Na ₂ O 0-10%, CaO + BaO 0-15%.

The upper dielectric layer is made of glass containing ZnO 25 to 45%, B ₂ O ₃ 15 to 35%, BaO 30 to 45%, and SiO ₂ 3 to 10% by mass percentage.

  The upper dielectric layer is made of glass having a softening point of glass constituting the lower dielectric layer plus a softening point of 20 ° C. or lower.

  The lower dielectric layer is made of glass having a softening point of 550 to 600 ° C.

The lower dielectric layer is made of glass containing PbO 50 to 75%, B ₂ O ₃ 2 to 35%, SiO _{2 2 to} 35%, ZnO + CaO 0 to 20% by mass percentage.

The lower dielectric layer, 25 to 45% ZnO in percent by _{mass, B 2 O 3 10~30%,} Bi 2 O 3 15~40%, SiO 2 0.5~10%, CaO + BaO + MgO + SrO 5~25% content It consists of the glass which does.

The lower dielectric layer is made of glass containing ZnO 15 to 50%, B ₂ O ₃ 26 to 60%, SiO ₂ 5 to 30, Li ₂ O + Na ₂ O + K ₂ O 3 to 20% by mass percentage. Features.

  In the plasma display panel dielectric forming method of the present invention, a lower dielectric material is applied to an electrode formed on a front glass substrate of a plasma display panel, fired, and then an upper dielectric material is applied and fired. A method for forming a dielectric for a display panel, wherein glass having a softening point of 545 to 600 ° C. is used as an upper dielectric material.

Further, as the upper dielectric material, PbO 25 to 55% in mass _{percentage, B 2 O 3 10~40%,} SiO 2 1~15%, BaO 5~30%, ZnO 3~35%, Al 2 O 3 0 A glass containing 10 to 10%, CaO + MgO + SrO + Bi ₂ O ₃ 0 to 20%, TiO ₂ + ZrO ₂ + SnO ₂ 0 to 10% is used.

Moreover, as an upper layer dielectric material, ZnO 15 to 55%, B ₂ O ₃ 26 to 60%, SiO ₂ 0 to 30%, Al ₂ O ₃ 0 to 10%, K ₂ O 3 to 20% by mass percentage, Glass containing Li ₂ O + Na ₂ O 0-10%, CaO + BaO 0-15% is used.

Moreover, as an upper-layer dielectric material, glass containing ZnO 25 to 45%, B ₂ O ₃ 15 to 35%, BaO 30 to 45%, and SiO ₂ 3 to 10% by mass percentage is used.

  Further, as the upper dielectric material, glass having an upper dielectric layer having a softening point not higher than + 20 ° C. of the glass constituting the lower dielectric layer is used.

  In firing the upper dielectric material, the glass used as the upper dielectric material is fired at a softening point of ± 10 ° C.

  The upper dielectric material of the plasma display panel of the present invention is a plasma display panel used for producing a dielectric structure having a lower dielectric layer covering an electrode and an upper dielectric layer formed on the lower dielectric layer. The upper dielectric material is made of glass having a softening point of 545 to 600 ° C.

Further, PbO 25 to 55% in mass _{percentage, B 2 O 3 10~40%,} SiO 2 1~15%, BaO 5~30%, ZnO 3~35%, Al 2 O 3 0~10%, CaO + MgO + SrO + Bi 2 It is characterized by being made of glass containing 0 to 20% O _{3 and} 0 to 10% TiO ₂ + ZrO ₂ + SnO ₂ .

Moreover, 15 to 55% ZnO in percent by _{mass, B 2 O 3 26~60%,} SiO 2 0~30%, Al 2 O 3 0~10%, K 2 O 3~20%, Li 2 O + Na 2 O 0 It is characterized by comprising a glass containing 10% to 10% and 0 to 15% CaO + BaO.

Moreover, 25 to 45% ZnO in percent by _{mass, B 2 O 3 15~35%,} BaO 30~45%, characterized in that it consists of glass containing SiO ₂ 3 to 10%.

  Further, it is characterized in that it is made of glass having a softening point not higher than + 20 ° C. of the glass constituting the lower dielectric layer.

  If the dielectric structure of the plasma display panel of the present invention is employed, a dielectric layer having no reaction with the silver electrode during firing, high transparency, and high withstand voltage can be obtained. Therefore, it is suitable as a dielectric structure of a plasma display panel.

  The dielectric structure of the present invention is formed of a two-layer dielectric of a lower dielectric layer and an upper dielectric layer. Moreover, the upper dielectric layer has a dielectric layer of 545 to 600 ° C. (preferably 545 to 595 ° C., more preferably Glass having a softening point of 545 to 590 ° C. is employed. By adopting such a dielectric structure, it is possible to obtain a dielectric layer having high transparency and high withstand voltage by suppressing the reaction with the silver electrode and at the same time suppressing the generation of bubbles during firing. When the softening point of the glass used for the upper dielectric layer is higher than 600 ° C., it becomes difficult to fire at a temperature of 600 ° C. or lower, and when it is lower than 545 ° C., bubbles tend to be generated at the time of baking, and transparency and withstand voltage are reduced. It is difficult to obtain a high dielectric layer.

  Further, in order to obtain a dielectric layer having higher transparency and withstand voltage, it is preferable to use glass whose viscosity change near the softening point is abrupt (short) in the upper dielectric layer. This is because by using such glass, the generated bubbles can be easily removed and the remaining bubbles can be reduced.

As a glass whose viscosity change near the softening point is abrupt (short), for example, PbO 25 to 55%, B ₂ O ₃ 10 to 40%, SiO ₂ 1 to 15%, BaO 5 to 30% in mass percentage, Glass (upper layer glass A) containing ZnO 3 to 35%, Al ₂ O ₃ 0 to 10%, CaO + MgO + SrO + Bi ₂ O ₃ 0 to 20%, TiO ₂ + ZrO ₂ + SnO ₂ 0 to 10%, ZnO 15 to 55 by mass percentage _{%, B 2 O 3 26~60%} , SiO 2 0~30%, Al 2 O 3 0~10%, K 2 O 3~20%, Li 2 O + Na 2 O 0~10%, CaO + BaO 0~15% (Upper layer glass B), ZnO 25-45% by mass percentage, B ₂ O ₃ 15-35%, BaO 30-45%, SiO ₂ 3-10%, glass containing (upper layer glass C). These glasses have a thermal expansion coefficient (about 85 × 10 ⁻⁷ / ° C.) of soda lime glass and 70 to 80 × 10 ^{− −} which meet the thermal expansion coefficient (about 83 × 10 ⁻⁷ / ° C.) of high strain point glass. ^It has a thermal expansion coefficient of ⁷ / ° C.

  It is also conceivable to form a single dielectric layer using only the above glass without using the lower dielectric layer. However, the glass may be very easily yellowed depending on the composition, and a two-layer structure should be adopted in order to obtain a stable dielectric layer without yellowing.

  When the dielectric structure is a two-layer structure, the upper dielectric layer has a softening point of + 20 ° C. or lower (preferably + 10 ° C. or lower, more preferably + 5 ° C. or lower) of the glass constituting the lower dielectric layer. It is preferable to use glass having When the softening point of the glass used for the upper dielectric layer is higher than the softening point of the glass used for the lower dielectric layer + 20 ° C., when the upper dielectric layer is fired, the lower dielectric layer that has already been fired is formed. , It becomes easy to soften and it becomes difficult to obtain surface smoothness. When the lower dielectric layer and the upper dielectric layer are co-fired at the same temperature, the glass used for the upper dielectric layer is a glass having a softening point of ± 20 ° C. or lower of the glass used for the lower dielectric layer. It is desirable to use it.

  The total thickness of the dielectric layer is preferably 30 to 40 μm. The thickness of the lower dielectric layer is 25 to 50% with respect to the entire dielectric layer, and the thickness of the upper dielectric layer is dielectric. It is desirable to adjust so that it may become the range of 50 to 75% with respect to the whole body layer. The reason is that if the thickness of the lower dielectric layer relative to the entire dielectric layer becomes too small, the upper dielectric layer and the electrode are likely to react and yellow easily, whereas the thickness of the lower dielectric layer relative to the entire dielectric layer This is because it becomes difficult to obtain a dielectric material having a high transmittance if is too large.

  Hereinafter, the reason for limiting the glass composition constituting the upper dielectric layer as described above will be described.

  The reason for limiting the composition of the upper glass A will be described.

  PbO is a component that lowers the softening point, and its content is 25 to 55%, preferably 30 to 50%. When PbO is less than 25%, the softening point exceeds 600 ° C., and thus many bubbles remain in the glass after firing. If it exceeds 55%, the thermal expansion coefficient becomes high.

B ₂ O ₃ is a component that expands the vitrification range and affects the defoaming property. The content of B ₂ O ₃ is 10 to 40%, preferably 15 to 35%. If B ₂ O ₃ is less than 10%, vitrification becomes difficult, and if it is more than 40%, the glass tends to phase-separate, which is not preferable.

SiO ₂ is a component that forms a glass skeleton, and its content is 1 to 15%, preferably 2 to 13%. If the SiO ₂ content is less than 1%, vitrification becomes difficult. If the SiO ₂ content exceeds 15%, the softening point becomes too high and firing at 600 ° C. or less becomes difficult. Further, since the viscosity change of the glass becomes gradual (long glass), it is difficult for bubbles to escape.

  BaO is a particularly important component for adjusting the high-temperature viscosity that lowers the softening point and affects defoaming properties, and its content is 5 to 30%, preferably 10 to 25%.

Although detailed reason is not known, in order to reduce the formation of bubbles during the _{firing, PbO, B 2 O 3,} SiO 2 and BaO is important to be in the above range.

  ZnO is a component that lowers the thermal expansion coefficient and lowers the softening point, and its content is 3 to 35%, preferably 5 to 30%. If the ZnO content is less than 3%, the above effect cannot be obtained. If the ZnO content is more than 35%, the glass tends to devitrify during firing.

Al ₂ O ₃ is a component for suppressing phase separation and obtaining uniform glass. Further, coexistence with TiO ₂ , ZrO ₂ and SnO ₂ has an effect of further increasing chemical durability. The content of Al ₂ O ₃ is 0 to 10%, preferably 1 to 8%. If the Al ₂ O ₃ content is more than 10%, the softening point increases and bubbles are difficult to escape. The reason why the dielectric material is required to have chemical durability is as follows. That is, in the dielectric material, the particle size distribution is strictly controlled in order to minimize the number of bubbles after firing. At that time, it is necessary to finely pulverize, but in the case of glass with low chemical durability, the surface after pulverization is likely to be deteriorated by mechanical energy at the time of pulverization, and conversely, fine bubbles are likely to be generated at the time of firing. Moreover, if it is left in a powder state having a large specific surface area, it easily reacts with moisture in the air and the surface is easily altered. When the surface of the powder is altered, bubbles are likely to be generated from the altered layer present at the powder grain boundary during firing. Therefore, it is desirable that the dielectric material has as high chemical durability as possible, particularly water resistance.

CaO, MgO, SrO and Bi ₂ O ₃ are components for lowering the softening point and adjusting high temperature viscosity that affects defoaming properties, and their content is 0 to 20% in total, preferably 0 ~ 18%. In addition, content of each component is CaO 0-20% (preferably 0-18%), MgO 0-20% (preferably 0-18%), SrO 0-20% (preferably 0-18%), Bi ₂ O _{3 is} 0 to 20% (preferably 0 to 18%). If the total amount of these components is more than 20%, the softening point will be too low, and foaming will easily occur during firing, and the thermal expansion coefficient will be too high. Moreover, when there is too much content of each component, it becomes easy to foam or to be highly expanded, and it is not preferable.

TiO ₂ , ZrO ₂ and SnO ₂ are components necessary for improving chemical durability. There is also an effect of finely adjusting the softening point. The total amount of TiO ₂ , ZrO ₂ and SnO ₂ is 0 to 10%, preferably 0.1 to 7%. If these components exceed 10%, the glass tends to be devitrified, which is not preferable. The content of each component is TiO ₂ 0-10% (preferably 0-7%, more preferably 0.5-5%), ZrO ₂ 0-10% (preferably 0-7%, more preferably). is 0 to 5%), SnO ₂ 0% (preferably 0 to 7%, more preferably from 0 to 5%).

In addition to the above components, the upper glass A can contain various components within a range that does not impair the required characteristics. For example, Sb ₂ O ₃ , CeO ₂ , La ₂ O ₃ , CuO, Ta ₂ O ₅ , Nb ₂ O ₅ , MnO ₂ , V ₂ O ₅ , CoO, NiO, Nd ₂ O _3, etc. in a total amount of 10% Can be added.

  Next, the reason why the composition of the upper glass B is limited will be described.

  ZnO is a component that lowers the softening point while being a main component constituting glass. The content of ZnO is 15 to 55%, preferably 20 to 40%. If the ZnO content is less than 15%, the above effect is insufficient. If the ZnO content is more than 55%, the glass is crystallized during firing and the transparency is impaired.

B ₂ O ₃ is a component that forms a glass skeleton, expands the vitrification range, and further affects defoaming properties. The content of B ₂ O ₃ is 26 to 60%, preferably 28 to 50%. If the B ₂ O ₃ content is less than 26%, the glass is easily crystallized at the time of firing and the transparency is impaired. If the content is more than 60%, the softening point of the glass becomes too high and firing at 600 ° C. or less becomes difficult.

SiO ₂ is a component that forms a glass skeleton. The content of SiO ₂ is 0 to 30%, preferably 1 to 25%. If SiO ₂ is more than 30%, the softening point of the glass becomes too high and firing at a temperature of 600 ° C. or lower becomes impossible. Further, since the viscosity change of the glass becomes gradual (long glass), it is difficult for bubbles to escape.

Al ₂ O ₃ is a component that suppresses the phase separation of glass. The content of Al ₂ O ₃ is 0 to 10%, preferably 0.5 to 8%. When Al ₂ O ₃ is more than 10%, the softening point becomes too high, and firing at a temperature of 600 ° C. or less becomes difficult.

K ₂ O is a component that lowers the melting point of the glass and adjusts the thermal expansion coefficient. Moreover, it is a component which suppresses yellowing by reaction with a silver electrode. The content of K ₂ O is 3 to 20%, preferably 3 to 15%. If the K ₂ O content is less than 3%, the above-described effects are not obtained.

Na ₂ O and Li ₂ O are components added to lower the melting point of the glass and adjust the thermal expansion coefficient. Those components are 0 to 10% in total amount, preferably 0 to 5%. When the total amount of these components is more than 10%, it is difficult to prevent yellowing due to reaction with the silver electrode even when K ₂ O is used.

  CaO and BaO are components added to lower the softening point of the glass or adjust the thermal expansion coefficient. Those components are 0 to 15% in total, preferably 0 to 10%. When the total amount of these components is more than 15%, the thermal expansion coefficient becomes larger than that of the glass substrate.

The upper glass B can contain various components in addition to the above components as long as the required characteristics are not impaired. For example _{TiO 2, ZrO 2, SnO 2} , Sb 2 O 3, CeO 2, La 2 O 3, CuO, Ta 2 O 5, Nb 2 O 5, MnO 2, V 2 O 5, CoO, NiO, Nd 2 O ₃ etc. can be added up to 10% in total.

  Next, the reason why the composition of the upper glass C is limited will be described.

  ZnO is a component that lowers the thermal expansion coefficient as well as lowering the softening point. The content of ZnO is 25 to 45%, preferably 25 to 40%. If the ZnO content is less than 25%, it is difficult to obtain the above effect. If the ZnO content is more than 45%, crystals are precipitated in the glass and a dense sintered body cannot be obtained.

B ₂ O ₃ is a component that forms a glass skeleton, expands the vitrification range, and further affects defoaming properties. The content of B ₂ O ₃ is 15 to 35%, preferably 15 to 30%. If the B ₂ O ₃ content is less than 15%, the glass is easily crystallized at the time of firing, and the transparency is impaired.

  BaO is a component that lowers the softening point and adjusts the thermal expansion coefficient. The content of BaO is 30 to 45%, preferably 35 to 45%. If BaO is less than 30%, the effect is not sufficient, and if it is more than 45%, the thermal expansion coefficient is larger than that of the glass substrate.

SiO ₂ is a component that forms a glass skeleton. The content of SiO ₂ is 3 to 10%, preferably 3 to 9%. If the SiO ₂ content is more than 10%, the softening point of the glass becomes too high and firing at a temperature of 600 ° C. or lower becomes impossible. Further, since the viscosity change of the glass becomes gradual (long glass), it is difficult for bubbles to escape.

In addition to the above components, the upper glass C can contain various components within a range that does not impair the required characteristics. For example _{TiO 2, ZrO 2, SnO 2} , Sb 2 O 3, CeO 2, La 2 O 3, CuO, Ta 2 O 5, Nb 2 O 5, MnO 2, V 2 O 5, CoO, NiO, Nd 2 O ₃ etc. can be added up to 10% in total.

Various glass materials can be used for the lower dielectric layer in the dielectric structure of the present invention. Lower The characteristics required for the dielectric layer, the thermal expansion coefficient of soda lime glass which is the material of the front glass plate (about 85 × 10 ^-7 / ℃) and thermal expansion coefficient of the high strain point glass (approximately 83 × 10 ^{- 7} / ° C.) and can be fired at a temperature of 600 ° C. or lower. Specifically, a glass having a thermal expansion coefficient of 70 to 80 × 10 ⁻⁷ / ° C. and a glass softening point in the range of 550 to 595 ° C. is preferable. Furthermore, it is important that the material is less susceptible to yellowing due to reaction with the silver electrode than the upper dielectric material.

As a lower layer dielectric material satisfying such requirements, for example, glass containing PbO 50 to 75%, B ₂ O ₃ 2 to 35%, SiO _{2 2 to} 35%, ZnO + CaO 0 to 20% by mass percentage (lower glass) A), 25~45% ZnO in percent by _{mass, B 2 O 3 10~30%,} Bi 2 O 3 15~40%, SiO 2 0.5~10%, CaO + BaO + MgO + SrO 5~25% content for glasses (lower glass B), 15~50% ZnO in percent by _{mass, B 2 O 3 26~60%,} SiO 2 5~30%, Li 2 O + Na 2 O + K 2 O 3~20% content for glasses (lower glass C) can be mentioned .

  Hereinafter, the reason for limiting the glass composition constituting the lower dielectric layer as described above will be described.

  The reason for limiting the composition of the lower glass A will be described.

  PbO is a component that lowers the softening point, and its content is 50 to 75%, preferably 55 to 70%. If the PbO content is less than 50%, the softening point exceeds 600 ° C., and many bubbles remain in the glass when fired at 600 ° C. or less. If it exceeds 75%, the thermal expansion coefficient becomes high.

B ₂ O ₃ is a component that widens the vitrification range, and its content is 2 to 35%, preferably 5 to 25%. If B ₂ O ₃ is less than 2%, vitrification becomes difficult, and if it exceeds 35%, the thermal expansion coefficient becomes too high.

SiO ₂ is a component that forms a glass skeleton, and its content is 2 to 35%, preferably 3 to 31%. If SiO ₂ is less than 2%, crystals are deposited during firing, and a transparent film cannot be obtained. If it is more than 35%, the softening point becomes too high, and firing at a temperature of 600 ° C. or lower becomes impossible.

  ZnO and CaO are components for finely adjusting the softening point of the glass, and their content is 0 to 20%, preferably 0 to 10%. If it exceeds 20%, the thermal expansion coefficient becomes too high. The contents of ZnO and CaO are ZnO 0 to 20% (preferably 0 to 15%) and CaO 0 to 20% (preferably 0 to 15%).

In addition, the lower layer glass A can add a various component in the range which does not impair the required characteristic other than the said component. For example, BaO, TiO ₂ , ZrO ₂ , SnO ₂ , Al ₂ O _{3 and the} like can be contained up to 10% in total.

  Next, the reason why the composition of the lower layer glass B is limited will be described.

  ZnO is a component that lowers the softening point and lowers the thermal expansion coefficient, and its content is 25 to 45%, preferably 25 to 40%. If the amount is less than 25%, the above-mentioned effects cannot be obtained. If the amount is more than 45%, the glass tends to devitrify, and it is difficult to obtain a uniform glass.

B ₂ O ₃ is a component that widens the vitrification range, and its content is 10 to 30%, preferably 15 to 30%. When B ₂ O ₃ is less than 10%, vitrification becomes difficult, and when it is more than 30%, the thermal expansion coefficient becomes too high.

Bi ₂ O ₃ is a component that adjusts the softening point, and its content is 15 to 40%, preferably 15 to 38%. When Bi ₂ O ₃ is less than 15%, the softening point becomes high, and when it exceeds 40%, the thermal expansion coefficient becomes too high.

SiO ₂ is a component that forms a glass skeleton, and its content is 0.5 to 10%, preferably 2 to 10%. If the SiO ₂ content is less than 0.5%, the glass tends to devitrify and it is difficult to obtain a uniform glass. If the SiO ₂ content exceeds 10%, the softening point becomes too high and the glass cannot be fired at a temperature of 600 ° C. or lower.

  CaO, BaO, MgO and SrO are components for lowering the softening point and adjusting the thermal expansion coefficient, and the total content thereof is 5 to 25%, preferably 7 to 20%. The content of each component is CaO 0-25% (preferably 0-20%), BaO 0-25% (preferably 0-20%), MgO 0-25% (preferably 0-20%). , SrO 0 to 25% (preferably 0 to 20%). If the total amount of these components is more than 25%, the softening point will be too low, and foaming will easily occur during firing, and the thermal expansion coefficient will be too high. Moreover, when there is too much content of each component, it becomes easy to foam or to be highly expanded, and it is not preferable.

In addition, the lower layer glass B can be added with various components in addition to the above components as long as the required characteristics are not impaired. For example, TiO ₂ , ZrO ₂ , SnO ₂ , Al ₂ O _{3 and the} like can be contained up to 10% in total.

  Next, the reason for limiting the composition of the lower glass C will be described.

  ZnO is a main component constituting glass and has a function of lowering the softening point, and its content is 15 to 50%, preferably 20 to 40%. If the ZnO content is less than 15%, the above effect is insufficient. If the ZnO content is more than 50%, the glass is crystallized during firing and the transparency is impaired.

B ₂ O ₃ is a component that forms a glass skeleton and widens the vitrification range, and its content is 26 to 60%, preferably 28 to 50%. If the B ₂ O ₃ content is less than 26%, the glass is easily crystallized at the time of firing and the transparency is impaired, and if it exceeds 60%, the softening point of the glass becomes too high and firing at 600 ° C. or less becomes difficult.

SiO ₂ is a component that forms a glass skeleton, and its content is 5 to 30%, preferably 5 to 25%. When SiO ₂ is more than 30%, the softening point of the glass becomes too high and firing at a temperature of 600 ° C. or less becomes difficult.

Li ₂ O is an alkali metal oxide, Na ₂ O, K ₂ O or by low-melting the glass, there is work to adjust the thermal expansion coefficient, the content thereof is 3-20% in total, preferably 10-20%. If the total amount is less than 3%, the above effect cannot be obtained.

K ₂ O has the effect of suppressing yellowing due to silver in addition to the above effects, and is desirably contained. The content of K ₂ O is preferably 3 to 20%, particularly preferably 7 to 15%. If the K ₂ O content is less than 3%, the above-described effects are not obtained. The content of Na ₂ O and Li ₂ O is 0 to 20%, preferably 0 to 10%, respectively.

  In addition, in the lower glass C, various components can be added in addition to the above components as long as the required characteristics are not impaired. For example, BaO, CaO, MgO and the like can be contained up to 10% in total.

  Next, a method for forming a dielectric layer having the above structure on the front glass plate of the plasma display panel will be described.

  First, an upper dielectric material and a lower dielectric material made of the glass powder described above are prepared.

It is important that the glass powder has a predetermined particle size distribution by pulverization using a ball mill, a fluid energy mill or the like, and further classification by airflow classification or the like. Specifically, each glass powder preferably has a maximum particle diameter D _MAX of 15 μm or less, particularly 8 to 14 μm. When D _MAX exceeds 15 μm, the distance between the particles becomes too large and a large number of bubbles remain, and the bubble diameter also increases, so that it is difficult to ensure sufficient transparency. Further, the surface smoothness of the dielectric layer is lowered, and the withstand voltage is deteriorated. When the maximum particle diameter D _MAX of the glass powder is smaller than 8 μm, the yield of the glass powder is lowered and the production efficiency is deteriorated. Furthermore, the particle size distribution of the glass powder is as follows: 90% particle diameter D ₉₀ is 7 μm or less (particularly 3 ≦ D ₉₀ <7 μm), 75% particle diameter D ₇₅ is 5 μm or less (particularly 2 ≦ D ₇₅ ≦ 5 μm), 50% particle diameter It is desirable that D ₅₀ is 3 μm or less (particularly 1 ≦ D ₅₀ ≦ 3 μm) and the 25% particle diameter D ₂₅ is 2 μm or less (particularly 0.5 ≦ D ₂₅ ≦ 2 μm). When larger than each particle diameter, the space | interval of particle | grains becomes large, the number of bubbles increases, or a bubble diameter becomes large and transparency falls. Further, the surface smoothness of the dielectric layer is likely to be lowered.

  In addition, filler powders such as alumina, zircon, zirconia, and titanium oxide can be added to each dielectric material in order to improve the glass strength after firing and adjust the appearance. In this case, the ratio of the glass powder to the filler powder is 90 to 100% by mass of the glass powder and 0 to 10% by mass of the filler powder. When there is more filler powder than 10%, visible light will be scattered and it will become opaque. The maximum particle size of the ceramic powder is preferably 15 μm or less.

  Next, each dielectric material is made into a paste or a green sheet.

  In the case of forming a paste, in addition to the dielectric material, a thermoplastic resin, a plasticizer, a solvent, and the like are used, and these are kneaded at a predetermined ratio to obtain an upper layer dielectric paste and a lower layer dielectric paste.

  In addition, it is preferable that content of dielectric material exists in the range of 30-90 mass% of the whole paste, especially 50-70 mass%. As described above, the dielectric material may contain ceramic powder.

  The thermoplastic resin is a component that increases the film strength after drying and imparts flexibility, and its content is in the range of 0.1 to 30% by mass, particularly 1 to 20% by mass of the entire paste. Is preferred. 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 preferably in the range of 0 to 50 mass%, particularly 5 to 30 mass% of the entire paste. 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 component for pasting the material, and the content thereof is preferably in the range of 5 to 60% by mass, particularly 20 to 50% by mass of the entire paste. 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.

  Dielectric layers are sequentially formed on the front glass plate on which the scanning electrodes are formed, using the lower dielectric forming paste and the upper dielectric forming paste thus prepared.

  Each dielectric layer is formed by first applying a lower-layer dielectric forming paste to a film thickness of about 30 to 40 μm by a screen printing method or a batch coating method on a front glass plate on which scanning electrodes have been previously formed. After drying at about 80 to 120 ° C., baking is performed at a temperature of 500 to 600 ° C. for 5 to 15 minutes. Subsequently, an upper layer dielectric forming paste is applied on the film to a thickness of about 40 to 50 μm by screen printing or a batch coating method, and dried at about 80 to 120 ° C. Thereafter, it is baked at a temperature of 500 to 600 ° C. for 5 to 15 minutes.

  In addition, when forming a green sheet, in addition to the dielectric material, a thermoplastic resin, a plasticizer, or the like is used, and a main solvent such as toluene or an auxiliary solvent such as isopropyl alcohol is added to the slurry to form a slurry. Is formed on a film of polyethylene terephthalate or the like by a doctor blade method or the like and dried to obtain a dielectric green sheet for upper layer and a lower dielectric green sheet.

  In addition, it is preferable that the ratio for which a dielectric material accounts in a green sheet exists in the range of 50-90 mass%, especially 60-80 mass%. As described above, the dielectric material may contain ceramic powder.

  As a thermoplastic resin and a plasticizer, the same thing as what was used for the said paste can be used, and as a ratio of a thermoplastic resin, it may exist in the range of 5-40 mass%, especially 5-30 mass%. Preferably, the proportion of the plasticizer is preferably 0 to 20% by mass, particularly preferably 0 to 10% by mass.

  Using the lower dielectric forming green sheet and the upper dielectric forming green sheet thus prepared, the dielectric layers are sequentially formed on the front glass plate on which the scan electrodes are formed.

  In addition, each dielectric layer is formed by first forming a lower dielectric film by thermocompression bonding a green sheet for forming a lower dielectric on a front glass plate on which a scanning electrode has been formed in advance, and then at 500 to 600 ° C. Bake at temperature for 5-15 minutes. Subsequently, the upper dielectric layer forming green sheet is thermocompression-bonded thereon to form an upper dielectric layer, and then baked at a temperature of 500 to 600 ° C. for 5 to 15 minutes.

  When the upper dielectric layer is formed, whether the paste or the green sheet is used, if the upper dielectric material is fired in the temperature range of ± 10 ° C. of the glass for the upper layer, it is generated at the interface of the glass powder. It becomes difficult for the grain boundary bubbles to grow, and the generation of large bubbles can be suppressed.

  In this manner, a dielectric layer having a two-layer structure including a lower dielectric layer having a thickness of 7.5 to 20 μm and an upper dielectric layer having a thickness of 15 to 30 μm is formed on the front glass substrate of the plasma display panel. it can.

  The glass combination used for the upper dielectric layer and the lower dielectric layer is not particularly limited. Upper glass A-lower glass A, upper glass A-lower glass B, upper glass A-lower glass C, upper layer Glass B-lower glass A, upper glass B-lower glass B, upper glass B-lower glass C, upper glass C-lower glass A, upper glass C-lower glass B, upper glass C-lower glass C A combination may be used. In particular, if you do not want to use PbO in consideration of the environment, a combination of upper glass B-lower glass B, upper glass B-lower glass C, upper glass C-lower glass B, upper glass C-lower glass C Is preferably used.

  In addition, when the firing temperatures of the upper dielectric material and the lower dielectric material are the same, in addition to the above formation method, after drying the lower dielectric film, forming the upper dielectric film, drying, A method of simultaneously firing both layers at a temperature can also be employed.

  Further, it is also possible to use a hybrid forming method in which the lower dielectric layer is formed using a paste and the upper dielectric layer is formed using a green sheet.

  Hereinafter, the dielectric structure of the plasma display of the present invention will be described in detail based on examples.

  Tables 1 to 3 show examples of the present invention (sample Nos. 1 to 9), and Table 4 shows comparative examples (samples No. 10 and 11).

Each sample in the table was prepared as follows.

  First, the raw materials were prepared so as to have the glass composition shown in Table by mass%, and mixed uniformly. Subsequently, after putting in a platinum crucible and melting at 1300 ° C. for 2 hours, the molten glass was formed into a thin plate shape. Subsequently, these were pulverized by a fluid energy mill, and airflow classification was performed to obtain a dielectric glass powder for a lower layer and an upper layer. The softening point and thermal expansion coefficient of the glass powder thus obtained were measured. The particle size of the glass powder was confirmed with a Shimadzu laser diffraction particle size distribution analyzer SALD-2000.

  Furthermore, 65% of glass powder, 5% of ethyl cellulose, and 30% of terpineol were kneaded to obtain a paste for forming a lower dielectric and an upper dielectric.

  Next, a lower layer dielectric forming paste is screen-printed on the surface of a 1.7 mm thick soda lime glass plate on which silver electrodes are formed, dried, and then fired at the temperature shown in the table for 10 minutes to obtain a film thickness of about 10 μm The lower dielectric layer was formed. Subsequently, sample No. As for Nos. 1 to 10, an upper dielectric layer having a thickness of about 20 μm was formed by screen-printing and drying an upper dielectric forming paste thereon and drying it, followed by baking at the temperature in the table for 10 minutes.

  The yellowing state, transmittance, bubble state, and surface roughness Ra of the dielectric layer thus obtained were evaluated. The results are shown in each table.

  As is apparent from the table, sample No. which is an example of the present invention is shown. Nos. 1 to 9 had no yellowing and had good transmittance of 85% or more. Further, the number of bubbles of 10 μm or more was as small as 5 or less, and the surface roughness Ra of the film was 0.15 μm or less, and a dielectric layer exhibiting excellent surface smoothness was obtained.

  On the other hand, sample No. which is a comparative example. 10 had as many as 20 bubbles of 10 μm or more, and the transmittance was as low as 78%. Sample No. 11 yellowing occurred.

In addition, the softening point was calculated | required from the macro type | mold DTA curve, and the value of the 4th inflection point was described. The thermal expansion coefficient was measured with a thermal expansion coefficient measuring device TMA, and was calculated by calculating an average thermal expansion coefficient of 30 to 300 ° C. The appearance of yellowing was visually evaluated. The transmittance was measured using a spectrophotometer. The state of bubbles was evaluated by counting the number of bubbles of 10 μm or more existing in a 1 cm ² range of the sample after firing using a stereomicroscope. The surface roughness of the glass film was measured using a stylus type surface roughness meter.

Claims (20)

  A dielectric structure of a plasma display panel having a lower dielectric layer covering an electrode and an upper dielectric layer formed on the lower dielectric layer, wherein the lower dielectric layer and the upper dielectric layer are made of glass. A dielectric structure of a plasma display panel, wherein the upper dielectric layer is made of glass having a softening point of 545 to 600 ° C. Upper dielectric layer, PbO 25 to 55% in mass _{percentage, B 2 O 3 10~40%,} SiO 2 1~15%, BaO 5~30%, ZnO 3~35%, Al 2 O 3 0~10 _2. The dielectric structure of a plasma display panel according to claim 1, wherein the dielectric structure is made of glass containing 1%, CaO + MgO + SrO + Bi ₂ O ₃ 0-20%, TiO ₂ + ZrO ₂ + SnO ₂ 0-10%. Upper dielectric layer, 15 to 55% ZnO in percent by _{mass, B 2 O 3 26~60%,} SiO 2 0~30%, Al 2 O 3 0~10%, K 2 O 3~20%, Li 2 _2. The dielectric structure of a plasma display panel according to claim 1, wherein the dielectric structure is made of glass containing 0 + 10% of O + Na2O and 0-15% of CaO + BaO. 2. The upper dielectric layer is made of glass containing ZnO 25 to 45%, B ₂ O ₃ 15 to 35%, BaO 30 to 45%, SiO ₂ 3 to 10% by mass percentage. The dielectric structure of the plasma display panel.   2. The dielectric structure of a plasma display panel according to claim 1, wherein the upper dielectric layer is made of glass having a softening point of glass constituting the lower dielectric layer + 20 ° C. or lower.   The dielectric structure of the plasma display panel according to claim 1, wherein the lower dielectric layer is made of glass having a softening point of 550 to 600 ° C. The lower dielectric layer is made of glass containing 50 to 75% PbO, _{2 to} 35% B ₂ O ₃ , _{2 to} 35% SiO ₂ , and 0 to 20% ZnO + CaO by mass percentage. Dielectric structure of plasma display panel. Glass in which the lower dielectric layer contains ZnO 25-45%, B ₂ O ₃ 10-30%, Bi ₂ O ₃ 15-40%, SiO ₂ 0.5-10%, CaO + BaO + MgO + SrO 5-25% by mass percentage The dielectric structure of the plasma display panel according to claim 1, comprising: The lower dielectric layer is made of glass containing ZnO 15 to 50%, B ₂ O ₃ 26 to 60%, SiO ₂ 5 to 30, Li ₂ O + Na ₂ O + K ₂ O 3 to 20% by mass percentage. The dielectric structure of the plasma display panel according to claim 1.   A dielectric formation method for a plasma display panel, in which a lower dielectric material is applied to an electrode formed on a front glass substrate of a plasma display panel and baked, and then an upper dielectric material is applied and baked. As a method for forming a dielectric for a plasma display panel, glass having a softening point of 545 to 600 ° C. is used. As upper dielectric material, PbO 25 to 55% in mass _{percentage, B 2 O 3 10~40%,} SiO 2 1~15%, BaO 5~30%, ZnO 3~35%, Al 2 O 3 0~10 11. The method of forming a dielectric material for a plasma display panel according to claim 10, wherein glass containing 0.1%, CaO + MgO + SrO + Bi ₂ O ₃ 0-20%, TiO ₂ + ZrO ₂ + SnO ₂ 0-10% is used. As the upper layer dielectric materials, 15 to 55% ZnO in percent by _{mass, B 2 O 3 26~60%,} SiO 2 0~30%, Al 2 O 3 0~10%, K 2 O 3~20%, Li 2 11. The method of forming a dielectric for a plasma display panel according to claim 10, wherein glass containing O + Na ₂ O 0-10% and CaO + BaO 0-15% is used. The glass containing ZnO 25 to 45%, B ₂ O ₃ 15 to 35%, BaO 30 to 45%, SiO ₂ 3 to 10% by mass percentage is used as the upper dielectric material. The dielectric material formation method of the plasma display panel of description.   11. The method of forming a dielectric for a plasma display panel according to claim 10, wherein the upper dielectric material is a glass having a softening point of glass constituting the lower dielectric layer plus 20 [deg.] C. or lower.   11. The method of forming a dielectric for a plasma display panel according to claim 10, wherein the upper dielectric material is fired at a temperature of a softening point of glass used as the upper dielectric material ± 10 ° C.   An upper dielectric material for a plasma display panel used for manufacturing a dielectric structure having a lower dielectric layer covering an electrode and an upper dielectric layer formed on the lower dielectric layer, wherein the dielectric material is 545 to 600 ° C. A dielectric material for an upper layer of a plasma display panel, characterized by comprising a glass having a softening point of PbO 25 to 55% in mass _{percentage, B 2 O 3 10~40%,} SiO 2 1~15%, BaO 5~30%, ZnO 3~35%, Al 2 O 3 0~10%, CaO + MgO + SrO + Bi 2 O 3 17. The upper dielectric material for a plasma display panel according to claim 16, wherein the upper dielectric material is made of glass containing 0 to 20%, TiO ₂ + ZrO ₂ + SnO ₂ 0 to 10%. ZnO 15-55% by mass percentage, B ₂ O ₃ 26-60%, SiO ₂ 0-30%, Al ₂ O ₃ 0-10%, K ₂ O 3-20%, Li ₂ O + Na ₂ O 0-10 The upper layer dielectric material of a plasma display panel according to claim 16, wherein the upper layer dielectric material is made of glass containing 0 to 15% of CaO + BaO. The upper layer of a plasma display panel according to claim 16, wherein the upper layer is made of glass containing ZnO 25 to 45%, B ₂ O ₃ 15 to 35%, BaO 30 to 45%, SiO ₂ 3 to 10% by mass percentage. Dielectric material.   17. The upper dielectric material of a plasma display panel according to claim 16, wherein the upper dielectric material of the plasma display panel is made of glass having a softening point of glass constituting the lower dielectric layer + 20 ° C. or lower.