JP2007031258A - Low melting glass, sealing composition and sealing paste - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide bismuth-based glass which can be used for sealing without being crystallized even when it is tentatively fired at a temperature higher than the sealing temperature and melted stably for a long period of time by using a material such as platinum or platinum-rhodium; a sealing composition comprising the glass; and a sealing paste. <P>SOLUTION: The sealing paste is obtained by mixing a refractory ceramic filler and vehicle with a powder of low melting glass containing substantially no lead, thallium, cadmium and vanadium and containing, by mass, 70-90% Bi<SB>2</SB>O<SB>3</SB>, 5-15% ZnO, 2-8% B<SB>2</SB>O<SB>3</SB>, 0.1-5% Al<SB>2</SB>O<SB>3</SB>, 0.01-2% SiO<SB>2</SB>, 0.01-5% CeO<SB>2</SB>, 0.01-5% CuO, 0.01-0.2% Fe<SB>2</SB>O<SB>3</SB>, and 0.05-5% of CuO+Fe<SB>2</SB>O<SB>3</SB>, wherein the total content of alkali metal oxides, such as Li<SB>2</SB>O, Na<SB>2</SB>O or K<SB>2</SB>O, and alkaline earth metal oxides, such as MgO, CaO, BaO or SrO, is <0.1%. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a sealing composition, and particularly does not substantially contain lead, thallium, cadmium and vanadium components (hereinafter referred to as lead components), and is a plasma display panel (hereinafter referred to as PDP). .) Is used for flat displays. The simple “%” notation used in this specification means “% by mass”.

Conventionally, a sealing composition typified by an outer peripheral seal of a PDP is generally a lead-based material composed of a lead-based glass powder such as PbO—SiO ₂ —B ₂ O ₃ and a filler such as a refractory ceramic powder. However, in recent years, development of a composition that can be sealed at a low temperature without containing a lead component or the like has been demanded from an environmental viewpoint.

  Known examples of low-melting glass that does not contain a lead component include phosphate glass, borosilicate glass, alkali silicate glass, and bismuth glass. Among them, bismuth-based glass has attracted attention because it can be fired at a low temperature and has excellent chemical durability.

Bismuth glass that has been developed so far has a coefficient of thermal expansion of 90 to 110 × 10 ⁻⁷ / ° C., and the thermal expansion of glass used for sealing displays and their accessories (such as flat backlights). In order to match the coefficient (70 to 80 × 10 ⁻⁷ / ° C.), a low expansion refractory ceramic filler was blended.

However, if the amount of ZnO contained in the low melting point glass component in the bismuth glass is small, the thermal expansion coefficient is as large as 110 × 10 ⁻⁷ / ° C. or more, and in order to lower this, a larger amount of refractory ceramic filler is blended. There was a problem that the viscosity of the material increased and sealing could not be performed at less than 500 ° C. (Patent Document 1).

Conversely, a low melting point glass containing a large amount of ZnO has also been developed, but the chemical durability of the low melting point glass is lowered because the content of Bi ₂ O ₃ is large and Al ₂ O ₃ is not contained. There was a problem (Patent Document 2).

  On the other hand, the sealing member formed by pasting the sealing composition in the production of the PDP suppresses the generation of bubbles due to excessive flow of the sealing portion. Further, the sealing member is applied to other members such as ribs, phosphors and electrodes. In order to suppress thermal damage, the sealing temperature was baked at 500 ° C. or lower (preferably 480 ° C. or lower). However, these other members are also manufactured by a baking process in the same manner as the sealing of the sealing member, and there has been a problem that if the baking is performed individually, the process becomes longer and the manufacturing cost increases. In recent years, as a countermeasure, a plurality of members are simultaneously fired to shorten the process, and the seal member is also degreased and pre-baked (hereinafter referred to as pre-baking) in combination with these members. . That is, the sealing temperature of the other member and the temporary firing temperature of the sealing member were the same temperature.

  Therefore, the firing temperature of the seal member has to be lower than the firing temperature of other members such as ribs, phosphors, and electrodes for the above reasons. As a result, the sealing temperature of the sealing member is lower than the pre-baking temperature, and low melting point glass that can be sealed without impairing fluidity even by such a method of use has begun to be demanded. The conventional lead-based glass has a wide sealing temperature range (when the low-melting glass is used as an amorphous glass, it means a temperature range in which the low-melting glass can be sealed without crystallization). The above required characteristics were satisfied.

However, this bismuth-based glass has a narrow sealing temperature range even if it can be sealed at a low temperature. If the pre-baking temperature exceeds this sealing possible temperature range, it is included in Bi ₂ O ₃ and its glass component. B ₂ O ₃ , ZnO, etc. are prone to crystal formation and cannot be sealed at the sealing temperature during the main firing.
In addition, bismuth-based glass is excellent in fluidity at 500 ° C. or higher than other low melting glass, and when pre-baked at 500 ° C. or higher, the sealing portion of the sealing member flows too much and a depression is generated at the center. After sealing, there was a problem that this part became a cavity and remained as residual bubbles or the adhesive surface was deformed, so that the airtightness could not be maintained.

Furthermore, for mass production, it is preferable to melt in a continuous melting furnace that continuously performs the process from charging of raw materials to molding. However, normally, bismuth-based glass, like lead-based glass, needs to be melted by heating to 1000 ° C or higher in order to obtain a homogeneous glass. Since glass is highly erodible, the amount of material melted from the brick surface (for example, alkali metal oxides and zirconia) increases, which becomes the crystal nucleus of the glass and causes crystallization of the glass during temporary firing. was there. In addition, since this glass has a very low viscosity during melting and a low surface tension, there was a problem that the glass leaked from the joint portion of the brick that spread due to erosion during operation, and the glass could not be melted stably for a long time. .
Japanese Patent Laid-Open No. 9-278483 Japanese Patent Laid-Open No. 10-139478

  As described above, along with the shortening of the manufacturing process, the sealing member is once heated to a temperature exceeding the temperature for originally performing the sealing in the pre-baking stage. Conventional lead-based materials can be sealed at a temperature lower than the pre-baking temperature in the next main baking after pre-baking. However, bismuth-based glasses that have been developed so far have not been found for glass that can be sealed at a temperature lower than the pre-baking temperature, especially in flat displays such as PDPs, and sealing is possible. However, no glass has been found that can provide a good seal because the sealing strength is weak or the foam remaining after sealing is increased.

  Further, even a melting furnace whose surface is coated with an alloy such as platinum or platinum-rhodium is not sufficient as a continuous melting furnace that can be mass-produced stably for a long period of time due to deterioration (erosion and cracking) of platinum and the like.

  Therefore, the present invention eliminates the problems in the above conventional sealing composition, can be sealed at a temperature below the pre-baking without crystallization even if pre-baked above the sealing temperature, and platinum or An object of the present invention is to provide a low melting point glass of bismuth-based glass which can be stably melted for a long period of time with a material such as platinum-rhodium, a sealing composition using this glass, and a sealing paste.

  As a result of intensive studies to solve the above-mentioned problems, the present inventor has found that a composition containing a low-melting-point glass powder containing a glass composition shown below and a refractory ceramic filler solves the above-mentioned problems. Based on this finding, the present invention has been completed.

That is, the invention corresponding to claim 1 of the present invention substantially does not contain a lead component or the like, and is expressed in mass%, Bi ₂ O ₃ 70 to 90%, ZnO 5 to 15%, B ₂ O ₃ 2. _{~8%, Al 2 O 3 0.1~5} %, SiO 2 0.01~2%, CeO 2 0.1~5%, CuO 0.01~5%, Fe 2 O 3 0.01~0 2%, CuO + Fe ₂ O ₃ 0.05-5%, and alkali metal oxides such as Li ₂ O, Na ₂ O, K ₂ O and alkaline earths such as MgO, CaO, BaO, SrO The total amount of metal oxide is less than 0.1%.

The invention corresponding to claim 2 contains substantially no lead component, etc., and is expressed in mass%, Bi ₂ O ₃ 70 to 90%, ZnO 5 to 15%, B ₂ O ₃ 2 to 8%, Al ₂ O ₃ 0.1-5%, SiO ₂ 0.01-2%, CeO ₂ 0.1-5%, CuO 0.01-4.99%, Fe ₂ O ₃ 0.01-0.2% CuO + Fe ₂ O ₃ 0.05 to 5%, and alkali metal oxides such as Li ₂ O, Na ₂ O and K ₂ O and alkaline earth metal oxides such as MgO, CaO, BaO and SrO The total amount was less than 0.1%.

The invention corresponding to claim 3 is the low-melting glass of the invention corresponding to claim 1 or 2, wherein Al ₂ O ₃ / Bi ₂ O ₃ = 0.01 to 0.1 in terms of molar ratio and (CuO + Fe ₂ O ₃ ) / Bi ₂ O ₃ = 0.01 to 0.05.

  The invention corresponding to claim 4 is the low melting point glass of the invention corresponding to any one of claims 1 to 3, and can be sealed at a temperature equal to or lower than this pre-baked without crystallizing even if pre-fired. .

  The invention corresponding to claim 5 is a low melting point glass powder of 60 to 99% by volume of the invention corresponding to any one of claims 1 to 4, zircon, cordierite, aluminum titanate, alumina, mullite, silica (quartz) , Α-quartz, quartz glass, cristobalite, tridymite, etc.), one or more refractories selected from the group consisting of tin oxide ceramics, β-eucryptite, β-spodumene, zirconium phosphate ceramics and β-quartz solid solution It is the sealing composition which mix | blended 1-40 volume% of the powder of a ceramic ceramic filler.

  The invention corresponding to claim 6 is a sealing paste obtained by mixing a vehicle with the composition of claim 5.

  The reason for limitation of each component of the low melting glass which comprises the sealing composition of this invention is demonstrated below.

Bi ₂ O ₃ is an oxide that forms the network of the glass of the present invention, and is preferably contained in the range of 70 to 90%. When Bi ₂ O ₃ is less than 70%, the softening point of the low-melting glass becomes high and it cannot be used as a sealing composition capable of low-temperature sealing. On the other hand, if it exceeds 90%, it will not vitrify and the thermal expansion coefficient will be too high. The content of Bi ₂ O ₃ is more preferably 75 to 85% by weight in consideration of the load softening point, the thermal expansion coefficient, and the like. Here, the load softening point is the second variation of the heat balance curve obtained by raising the temperature of the glass-coated sample at a rate of 10 ° C./min using a differential thermal analyzer (DTA). The temperature indicated by the inflection point.

  ZnO is a component that lowers the thermal expansion coefficient and lowers the load softening point, and is preferably contained in the range of 5 to 15%. If ZnO is less than 5%, vitrification is difficult, and if it exceeds 15%, the stability at the time of molding a low-melting-point glass is poor and devitrification is likely to occur, and glass may not be obtained. The ZnO content is more preferably 7 to 12% in consideration of the stability of the glass and the like.

Al ₂ O ₃ is a component that lowers the coefficient of thermal expansion and improves the stability of the low-melting glass during temporary firing, and is preferably contained in the range of 0.1 to 5%. When Al ₂ O ₃ is less than 0.1%, crystal nuclei or crystals are precipitated in the low-melting glass at the time of calcining at 500 ° C. or higher, and cannot be sealed at a temperature lower than that at the calcining. On the other hand, if it exceeds 5%, the viscosity of the glass increases, and Al ₂ O ₃ may remain as an unmelted material in the low-melting glass. Considering the thermal expansion coefficient, the stability of the glass, the meltability, etc., it is more preferably 0.5 to 2%.

Further, in order to expand the temperature range where low-melting glass can be sealed and to generate crystals even if pre-baked at a temperature higher than the expected sealing temperature, Al ₂ O ₃ / Bi ₂ O ₃ = 0.01- 0.1 is preferable. When the molar ratio is less than 0.01, crystal nuclei or crystals are precipitated in the low-melting glass at the time of pre-baking and cannot be sealed at a temperature lower than that of pre-baking. On the other hand, when the molar ratio exceeds 0.1, the viscosity of the glass increases, and even when the glass is melted at 1200 ° C., Al ₂ O ₃ is not completely melted. If Al ₂ O ₃ / Bi ₂ O ₃ is in the above range, a stable glass network can be formed without crystallizing the glass even if pre-baking at a temperature higher than the expected sealing temperature.

As a result of the inventors' investigation, SiO ₂ is an essential component for suppressing excessive flow of the sealing composition during temporary firing and reducing residual foam after sealing, and further refractory during glass melting Has the effect of suppressing the erosion. Moreover, there exists an effect which reduces a thermal expansion coefficient and improves the stability of the low melting glass at the time of temporary baking, and it is preferable to make it contain in 0.01 to 2% of range. When SiO ₂ is less than 0.01%, an excessive flow is not suppressed at the time of pre-baking at 500 ° C. or more, and a refractory during melting is easily eroded. If it exceeds 2%, the viscosity of the glass increases, sealing at 500 ° C. or lower becomes difficult, and the melting temperature of the glass increases, so that the deterioration of the refractory is accelerated. Considering the thermal expansion coefficient, glass stability, meltability, etc., it is more preferably 0.1 to 1.5%.

B ₂ O ₃ is a component that forms a glass skeleton and widens the range in which vitrification is possible, and is preferably contained in an amount of 2 to 8%. If B ₂ O ₃ is less than 2%, vitrification becomes difficult, and if it exceeds 8%, the softening point becomes too high, and even if a load is applied during sealing, sealing at low temperatures becomes difficult. The content of B ₂ O ₃ is more preferably 3 to 7% in consideration of the thermal expansion coefficient, glass stability, load softening point, and the like.

Furthermore, in order to obtain a low melting point glass stably, it is preferable that the relationship of B ₂ O ₃ with respect to ZnO satisfies the relationship of B ₂ O ₃ /ZnO=0.4 to 1.0 in terms of molar ratio. When the molar ratio is less than 0.4 and exceeds 1.0, devitrification occurs in the glass after melting, and vitrification becomes difficult. More preferably, the relationship of 0.5 to 0.9 is satisfied.

Fe ₂ O ₃ is an essential component for expanding the sealable temperature range by suppressing crystallization at the time of sealing without almost increasing the viscosity, but when added excessively, the vitrification range becomes narrow. Therefore, the content is preferably 0.01 to 0.2%.

  CuO is an essential component for lowering the viscosity of the glass, especially for expanding the temperature range where sealing is possible on the low temperature side, and its content is 0.01 to 5% or 0.01 to 4.99%, preferably It is 0.1 to 3% or 0.1 to 1.99%, more preferably 0.1 to 1.5% or 0.1 to 1.49%. When CuO exceeds 5% or 4.99%, the precipitation rate of crystals increases and there is no effect of expanding the temperature range that can be sealed on the high temperature side, and when it is less than 0.01%, the temperature range that can be sealed on the low temperature side. There is no effect to spread. In addition, it is preferable to avoid excessive addition since the phosphor may be deteriorated in electronic parts.

Further, CuO and Fe ₂ O ₃ are essential components for improving the fluidity of the glass at 480 ° C. or less and stabilizing the glass at the time of temporary firing, and the total amount thereof is 0.05 to 5%. It is preferable. If it is less than 0.05%, the above effect cannot be obtained, and if it is more than 5%, the glass becomes unstable and the temperature range at which sealing can be performed on the high temperature side becomes narrow and crystallization tends to occur. A more preferable range is 0.1 to 2%, and a further preferable range is 0.1 to 1.5.

Moreover, expanding the sealable temperature range, in order to achieve both sealable viscosity at the crystallization-inhibitor and the temporary baking temperature below the temperature during false firing at sealing predetermined temperature or higher, for Bi ₂ O ₃ The relationship between Fe ₂ O ₃ and CuO preferably satisfies the relationship (CuO + Fe ₂ O ₃ ) / Bi ₂ O ₃ = 0.01 to 0.05 in terms of molar ratio. If the molar ratio is less than 0.01, glass fluidity sufficient for sealing at low temperatures cannot be obtained even when a load is applied, and if the molar ratio exceeds 0.05, the sealable temperature range is narrow. As a result, the glass is crystallized at a temperature higher than the expected sealing temperature, and the low-melting glass targeted by the present invention cannot be obtained. Cu and Fe are elements that are likely to cause valence changes. When added within the above range, the viscosity of the glass decreases, and the valence change during heating suppresses the valence change of Bi, and the glass crystallizes. There is an effect of not.

CeO ₂ has the effect of suppressing Bi ₂ O ₃ in the glass composition from precipitating as metal bismuth during glass melting and stabilizing the fluidity of the glass, so its content is 0.1 to 5%. is there. If the content is less than 0.1%, the above effect cannot be obtained. If the content is 5% or more, the viscosity of the glass is increased and it becomes difficult to seal at 480 ° C. or less. Preferably it is 0.1 to 3%, More preferably, it is 0.1 to 1.5%.

Further, when an alkali metal oxide such as Li ₂ O, Na ₂ O and K ₂ O and an alkaline earth metal oxide such as MgO, CaO, BaO and SrO are contained in an amount of 0.1% or more, the preliminary firing temperature is 480 ° C. or more. In order to generate ultraviolet rays, the alkali metal element or alkaline earth metal element diffuses inside the display element of a flat display such as a PDP by heating and depressurizing. Interfering with the mixed gas to be sealed, reducing the amount of ultraviolet rays generated, or moving part of the above elements to the dielectric or electrode material that is in contact with the sealing composition at the time of prefiring to change the dielectric constant There is a possibility that the conductivity is deteriorated. Furthermore, it has been found that when bismuth-based glass is melted with a crucible made of platinum or an alloy containing platinum as a main component, these refractories are likely to be accelerated (eroded or cracked). In order to solve these problems, the total of alkali metal oxides and alkaline earth metal oxides in the glass raw material is preferably less than 0.1%, more preferably 0.01% or less. .

In addition, the composition other than the above is within 3% within a range of Ag ₂ O, Co ₂ O ₃ , MoO ₃ , Nb ₂ O ₃ , Ta ₂ O ₅ , Ga ₂ O ₃ , Sb ₂ O ₃ , WO ₃ , P ₂ O ₅ , SnO x (x = 1 or 2), Cs ₂ O and the like can be contained, but addition of highly toxic components such as lead, thallium, cadmium, vanadium must be avoided from the viewpoint of environmental problems.

The glass having the above composition is an amorphous glass having a low glass transition point of 400 ° C. or less and showing good fluidity. In addition, the thermal expansion coefficient at 30 to 300 ° C. is 90 × 10 ⁻⁷ / ° C. or more and 110 × 10 ⁻⁷ / ° C. or less, and high expansion material suitable for this is sealed without blending a refractory ceramic filler. Is possible.

  On the other hand, when sealing various packages and display devices made of materials that do not conform to the thermal expansion coefficient, it is necessary to use a mixture of refractory ceramic fillers to correct the difference in thermal expansion coefficient from the material to be sealed. Is possible. A fire-resistant ceramic filler can also be used when mechanical strength is insufficient.

  When mixing the refractory ceramic filler, the mixing ratio is preferably 60 to 99% by volume of the low-melting glass powder and 1 to 40% by volume of the refractory ceramic filler. The reason for limiting the ratio of the two in this way is that if the refractory ceramic filler is less than 1% by volume, the effect is not achieved, and if it exceeds 40% by volume, the fluidity is deteriorated.

Examples of the refractory ceramic filler include zircon, cordierite, aluminum titanate, alumina, mullite, silica (quartz, α-quartz, quartz glass, cristobalite, tridymite, etc.), tin oxide ceramic, β-eucryptite, β- It is preferable to use at least one selected from the group consisting of spodomen, zirconium phosphate ceramics and β-quartz solid solution. Particularly filler mainly composed of Al ₂ O ₃ or SiO ₂ is part of the Al ₂ O ₃ or SiO ₂ at the time of calcination has the effect of suppressing the crystallization during calcination eluting the glass.

However, if these components are eluted too much, the glass viscosity is increased and sealing becomes impossible. Therefore, the specific surface area of these fillers is 5 m ² / g or less, preferably 3 m ² / g or less. The value of the specific surface area is measured by the gas adsorption BET method specified in JIS R 1626. Moreover, it is also possible to use black pigments, such as a Fe-Co-Cr complex oxide type, as a heat-resistant pigment.

  The vehicle used in the present invention is, for example, methyl cellulose, ethyl cellulose, carboxymethyl cellulose, oxyethyl cellulose, benzyl cellulose, propyl cellulose, nitrocellulose, etc. dissolved in a solvent such as terpineol, butyl carbitol acetate, ethyl carbitol acetate, etc. And acrylic resins such as methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-hydroxyethyl methacrylate, for example, methyl ethyl ketone, terpineol, butyl carbitol acetate, ethyl carbitol acetate, etc. And those dissolved in these solvents.

  The viscosity of the sealing glass paste may be adjusted to the viscosity suitable for the apparatus applied to the substrate, and can be adjusted by the ratio of the resin and the solvent and the ratio of the vehicle and the sealing composition.

  Known additives can be added to the glass paste for sealing, such as an antifoaming agent and a dispersing agent.

  For the production of the sealing glass paste, a known method such as a rotary mixer equipped with a stirring blade, a roll mill, a ball mill or the like can be used.

  Since the bismuth-based glass composition of the present invention does not contain a lead component or the like, there is no fear of causing environmental problems. In addition, the sealable temperature range is wide and it is possible to perform sealing without crystallizing even if pre-baking above the sealing temperature, and simultaneous baking with a plurality of members carried out in the mass production process of PDP is possible. .

In addition, the low melting point glass of the present invention is less than 0.1% in total of alkali metal oxides and alkaline earth metal oxide components, and has SiO ₂ as an essential component to prevent erosion of the refractory during melting. Since it can suppress, even if it fuse | melts with refractories, such as platinum and platinum- rhodium, almost no deterioration is recognized and it can operate stably in mass production. Further, by suppressing the mixing of alkali metal oxide and alkaline earth metal oxide, there is no occurrence of defective color development of the phosphor after sealing, a change in dielectric constant of the dielectric, and a decrease in conductivity of the electrode.

The low melting point glass of the present invention substantially does not contain a lead component or the like, and is expressed by mass%, Bi ₂ O ₃ 70 to 90%, ZnO 5 to 15%, B ₂ O ₃ 2 to 8%, Al _2. O ₃ 0.1-5%, SiO ₂ 0.01-2%, CeO ₂ 0.1-5%, CuO 0.01-5%, Fe ₂ O ₃ 0.01-0.2%, CuO + Fe ₂ O ₃ 0.05 to 5%, contains, and the total amount of Li ₂ O, Na ₂ O, an alkali metal oxide K ₂ O, etc., and MgO, CaO, BaO, alkaline earth metal oxides such as SrO Is less than 0.1%.

  Then, the raw materials were mixed so as to be in the composition range described above to obtain a batch raw material, and this batch raw material was put in a platinum crucible and put in a furnace adjusted to 1000 to 1200 ° C. and melted for 30 to 90 minutes. The melted glass was formed into a sheet shape with a water-cooled roller, pulverized with a ball mill, and then passed through a 150-mesh sieve to obtain a low-melting glass.

  60% to 99% by volume of this low melting glass, zircon, cordierite, aluminum titanate, alumina, mullite, silica (crystal, α-quartz, quartz glass, cristobalite, tridymite, etc.), tin oxide ceramic, β-eucrypt A sealing composition was prepared by mixing 1 to 40% by volume of a powder of one or more refractory ceramic fillers selected from tight, β-spodumene, zirconium phosphate ceramic and β-quartz solid solution. Then, the sealing composition is made into a paste with an organic vehicle or the like that decomposes below the glass softening point so that it can be easily applied to an object to be sealed. Moreover, you may use, after shape | molding the composition for sealing previously in the shape of a to-be-adhered part.

  Hereinafter, examples and comparative examples of the present invention will be described in detail with reference to Tables 1 to 3.

Example 1 As shown in Table 1, Bi ₂ O ₃ 82.46%, B ₂ O ₃ 5.68%, ZnO 10.67%, SiO ₂ 0.15%, CeO ₂ 0.20%, The raw materials are prepared so as to be 0.62% Al ₂ O ₃ , 0.10% Fe ₂ O _{3, and} 0.10% CuO to obtain a batch raw material. This batch raw material was put into a platinum crucible, put into a melting furnace adjusted to 1100 ° C., and melted for 50 minutes. The molten glass was formed into a sheet shape with a water-cooled roller, and the glass having passed through a 150-mesh sieve was used as the low melting glass.

The low melting point glass has a Al ₂ O ₃ / Bi ₂ O ₃ molar ratio of 0.035, a (Fe ₂ O ₃ + CuO) / Bi ₂ O ₃ molar ratio of 0.011, and B ₂ O ₃ / ZnO. The molar ratio was 0.62.

To 77% by volume of this low-melting glass, 23% by volume of cordierite was added as a refractory ceramic filler to obtain a sealing composition. The specific surface area of cordierite was 3 m ² / g or less. The glass transition point, load softening point, and softening point of this sealing composition were determined by a differential thermal analyzer (DTA). The glass transition point was 354 ° C, the load softening point was 379 ° C, and the softening point was 403 ° C. .

The sealing composition had a flow button diameter of 21 mm, a sealing temperature after calcination at 500 ° C. of 460 ° C., and a thermal expansion coefficient of 71 × 10 ⁻⁷ / ° C. These measuring methods are shown below.

Flow button diameter: This indicates the fluidity of the composition at the time of sealing, and a sample powder (6.0 g) of the sealing composition is pressed into a cylindrical shape having a diameter of 12.7 mm with a load of 50 to 100 kg / cm ^2. It is the diameter which the composition for sealing flowed when it hold | maintained for 10 minutes at 480 degreeC after shaping | molding. The flow button diameter is desirably 17 mm or greater and 26 mm or less. If the thickness is less than 17 mm, the glass composition is not sufficiently softened and does not adhere to the object to be sealed. If it is larger than 26 mm, the glass will flow too much and, after sealing, residual bubbles will be formed due to cavities, or the bonding surface will be deformed.

  Coefficient of thermal expansion: The sealing composition is filled in an alumina container, baked at 490 ° C. for 10 minutes, cooled, and then polished into a cylindrical shape having a length of 15 mm and a diameter of 5 mm. The amount of elongation was measured with a temperature increase rate of 10 ° C./min using a Rigaku thermomechanical analyzer 8310), and an average coefficient of thermal expansion of 30 to 300 ° C. was calculated.

  The glass paste was prepared by mixing the vehicle and the sealing composition as shown below.

  Vehicle: 3% ethyl cellulose as a resin, 20% terpineol as a solvent, 72% butyl carbitol acetate and 5% isoamyl acetate were stirred for 2 hours while heating to 60 ° C.

  Paste: A sealing paste was obtained by adding a vehicle to the sealing composition at a mass ratio of 86:14 and mixing with a roll mill. When the viscosity of the paste was measured with a B-type viscometer (HDBVII + manufactured by Brookfield), it was 55 Pa · s.

The sealing temperature was measured as follows. First, a sample substrate is prepared by applying the paste obtained above on a glass substrate (Asahi Glass Co., Ltd .: PD-200) with a thickness of 400 to 500 μm and a width of 3 mm. After pre-baking this sample substrate in an electric furnace set to the pre-baking temperature, another glass substrate is put on this sample substrate and a load of 500 g / cm ² is applied to the coating area of the sealing composition. A temperature at which bonding was possible when the distance between the glass substrates after baking was 200 μm or less was shown.

  The erodibility of platinum was obtained by charging the platinum crucible with a raw material and melting it 20 times. The portion where the glass of the platinum crucible was in contact every 5 times was confirmed with a microscope.

From the above results, the sealing composition of Example 1 was able to seal the glass substrate at 460 ° C. after the pre-baking without crystals being precipitated in the glass even when pre-baking at 500 ° C. . Moreover, since the glass does not contain alkali metal components (Li ₂ O, Na ₂ O and K ₂ O) and alkaline earth metal components (MgO, CaO, BaO, SrO), platinum erosion is not observed. It was.

(Examples 2 to 18)
Examples 2 to 18 are examples in which sealing compositions were prepared by the same method as in Example 1.

  As shown in Tables 1 and 2, the glass was melted in the same manner as in Example 1 except that the raw materials were mixed into batch raw materials, formed into a sheet by a water-cooled roller, and passed through a sieve with 150 mesh openings. This was used as a low melting glass.

The low melting point glass has a Al ₂ O ₃ / Bi ₂ O ₃ molar ratio of 0.028 to 0.086, a (CuO + Fe ₂ O ₃ ) / Bi ₂ O ₃ molar ratio of 0.010 to 0.047, B The molar ratio of ₂ O ₃ / ZnO is 0.62 to 0.80. Even when the sealing composition in which the low-melting glass and the refractory ceramic filler were mixed was fired at a temporary firing temperature of 500 to 550 ° C., no crystal deposition was observed in all the glasses. Moreover, since the load softening point of low melting glass is 378-409 degreeC, it can be made to flow fully at 480 degrees C or less also as a sealing composition by mixing a refractory ceramic filler. Actually, as shown in Tables 1 and 2, when the flow button diameter of the sealing composition was measured, it was 17 to 24 mm.

  In this sealing composition, Examples 2 to 5, 15 to 17 were the same method as Example 1, Examples 6 to 10 and 18 were the composition, 3% nitrocellulose for resin, 20% terpineol for solvent, A vehicle prepared by stirring 2 hours while heating butyl carbitol acetate 72% and isoamyl acetate 5% to 80 ° C., Examples 11 to 14 are the composition, 3% methyl methacrylate as resin, and terpineol as solvent. A vehicle prepared by stirring 30% and 67% butyl carbitol acetate while stirring at 70 ° C. for 2 hours was added at a mass ratio of 86:14 and mixed with a roll mill to obtain a sealing paste. When the viscosity of the paste was measured with a B-type viscometer, it was 54 to 74 Pa · s.

  Moreover, when the sealing temperature was evaluated using this paste, it was possible to bond the substrates in the range of 440 to 480 ° C.

When the thermal expansion coefficient of this sealing composition was measured using TMA, it was 68 to 75 × 10 ⁻⁷ / ° C., which was very close to the thermal expansion coefficient of the glass used for PDP and was distorted after sealing. There is nothing.

  In the present invention, no deterioration was observed in the platinum crucible even after fusing 15 times in all examples. Further, in Examples 1 to 14 containing no alkali metal component or alkaline earth metal component, no deterioration or erosion was observed in the platinum crucible even after the 20th melting.

In addition, in the refractory ceramic filler, Tables 1 and 2 show only those using silica glass among the components contained in silica, but the same effect is obtained with other quartz, α-quartz, cristobalite and tridymite. was gotten. Moreover, although the specific surface area of the used refractory ceramic filler is not indicated, the specific surface area of each was 5 m ² / g or less.

(Comparative Example 1)
Comparative Example 1 is an example not containing Al ₂ O ₃ , Fe ₂ O ₃ and CuO. The obtained sealing composition crystallized when pre-baked at 480 ° C. and could not be sealed.

(Comparative Example 2)
Comparative Example 2 is an example not containing Al ₂ O ₃ . The obtained sealing composition crystallized when pre-baked at 480 ° C. and could not be sealed.

(Comparative Example 3)
Comparative Example 3 is an example not containing Fe ₂ O ₃ . The obtained sealing composition crystallized when pre-baked at 480 ° C. and could not be sealed.

(Comparative Example 4)
Comparative Example 4 is an example not containing CuO. The resulting sealing composition was slightly crystallized at 480 ° C. and could not be sealed.

(Comparative Example 5)
Comparative Example 5 is an example in which a _{(Fe 2 O 3 + CuO)} / molar ratio of Bi ₂ O ₃ is _{(Fe 2 O 3 + CuO)} / Bi 2 O 3> 0.05. The obtained sealing composition crystallized when pre-baked at 480 ° C. and could not be sealed.

(Comparative Example 6)
Comparative Example 4 is an example in which the molar ratio of _{Al 2 O 3 / Bi 2 O} 3 is in the <0.01 _{Al 2 O 3 / Bi 2 O} 3. The obtained sealing composition crystallized when pre-baked at 480 ° C. and could not be sealed.

(Comparative Example 7)
Comparative Example 7 is an example in which the molar ratio of _{Al 2 O 3 / Bi 2 O} 3 is in the _{Al 2 O 3 / Bi 2 O} 3> 0.1. The resulting sealing composition did not crystallize even when pre-baked at 550 ° C., but the viscosity of the low-melting glass was increased, and the flow button of 480 ° C. was less than 16 mm and the fluidity was poor and could not be sealed. . Further, in order to melt the glass, it is necessary to raise the melting temperature to 1250 ° C. When the platinum crucible was observed after the 15th melting, slight erosion was observed at the bottom.

(Comparative Example 8)
In Comparative Example 8, the amount of SiO ₂ added exceeded 2%. The obtained sealing composition did not crystallize even when pre-baked at 570 ° C., but the viscosity of the low-melting glass was high, and the flow button at 480 ° C. was less than 16 mm, and the fluidity was poor and could not be sealed. Further, in order to melt the glass, it is necessary to raise the melting temperature to 1250 ° C. When the platinum crucible was observed after the 15th melting, slight erosion was observed at the bottom.

(Comparative Example 9)
Comparative Example 9 is an example not containing SiO ₂ . The resulting sealing composition did not crystallize even when pre-baked at 500 ° C., and could be sealed at 430 ° C., but a streak-like residue probably due to a dent generated during pre-baking near the center of the sealing surface Foam was generated and it was not suitable as a sealing material. Further, when the platinum crucible was observed after the 15th melting, slight erosion was observed at the bottom.

(Comparative Example 10)
Comparative Example 10 is an example in which the molar ratio of B ₂ O ₃ / ZnO is 1 or more. In this comparative example, crystals were already deposited in the glass obtained by melting, and a low-melting glass could not be obtained.

(Comparative Example 11)
Comparative Example 11 is an example in which the total amount of alkaline earth metal components (CaO and BaO) exceeds 0.1%. All of the obtained sealing compositions were crystallized by calcination at 480 ° C. and could not be sealed. Further, when the platinum crucible was observed after the tenth melting, a slight erosion was observed at the bottom, and a crack occurred at the bottom of the crucible 15 to 20, and the melting of the glass could not be continued.

  Since the sealing composition of the present invention may be crystallized at a temperature exceeding 550 ° C., it can be used as a lead-free crystallized glass of a member that can be sealed at a high temperature exceeding 550 ° C.

Claims (6)

Substantially free of lead, thallium, cadmium and vanadium components, expressed in terms of mass%, Bi ₂ O ₃ 70-90%, ZnO 5-15%, B ₂ O ₃ 2-8%, Al ₂ O _{3 0.1~5%, SiO 2 0.01~2%} , CeO 2 0.1~5%, CuO 0.01~5%, Fe 2 O 3 0.01~0.2%, CuO + Fe 2 O ₃ and a total amount of alkali metal oxides such as Li ₂ O, Na ₂ O and K ₂ O and alkaline earth metal oxides such as MgO, CaO, BaO and SrO A low-melting glass characterized by being less than 0.1%. Substantially free of lead, thallium, cadmium and vanadium components, expressed in terms of mass%, Bi ₂ O ₃ 70-90%, ZnO 5-15%, B ₂ O ₃ 2-8%, Al ₂ O _{3 0.1~5%, SiO 2 0.01~2%} , CeO 2 0.1~5%, CuO 0.01~4.99%, Fe 2 O 3 0.01~0.2%, CuO + Fe ₂ O ₃ 0.05 to 5%, and the total of alkali metal oxides such as Li ₂ O, Na ₂ O, K ₂ O and alkaline earth metal oxides such as MgO, CaO, BaO, SrO Low melting point glass characterized in that the amount is less than 0.1%. A molar ratio of Al ₂ O ₃ / Bi ₂ O ₃ = 0.01 to 0.1 and satisfying a relationship of (CuO + Fe ₂ O ₃ ) / Bi ₂ O ₃ = 0.01 to 0.05 The low melting point glass according to claim 1 or 2. The low-melting glass according to any one of claims 1 to 3, which can be sealed at a temperature equal to or lower than the pre-baking without crystallizing even if pre-baking. 60 to 99% by volume of the low melting glass powder according to any one of claims 1 to 4, and zircon, cordierite, aluminum titanate, alumina, mullite, silica (crystal, α-quartz, quartz glass, cristobalite, tridymite. Etc.), 1 to 40% by volume of powder of one or more refractory ceramic fillers selected from the group consisting of tin oxide ceramics, β-eucryptite, β-spodumene, zirconium phosphate ceramics and β-quartz solid solution A sealing composition. A sealing paste obtained by mixing a sealing composition according to claim 5 with a vehicle.