JP2006111512A - Lead-free glass having low melting point - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide lead-free glass having a low melting point, which is prevented from yellowing due to silver reaction and has high visible light transmittance, and which is required in the development of an electronic material substrate represented by a plasma display panel. <P>SOLUTION: The lead-free glass having a low melting point is an SiO<SB>2</SB>-B<SB>2</SB>O<SB>3</SB>-ZnO-R<SB>2</SB>O-CuO-based glass, which contains, by weight, 7-20% SiO<SB>2</SB>, 32-50% B<SB>2</SB>O<SB>3</SB>, 25-42% ZnO, 7-20% R<SB>2</SB>O(Li<SB>2</SB>O+Na<SB>2</SB>O+K<SB>2</SB>O), 0.1-2% CuO, 0-2% MnO<SB>2</SB>, and 0-10% RO(MgO+CaO+SrO+BaO) and is characterized in that the weight ratio of B<SB>2</SB>O<SB>3</SB>to ZnO is within a range of 0.85-2, the weight ratio of (B<SB>2</SB>O<SB>3</SB>+R<SB>2</SB>O) to SiO<SB>2</SB>is within a range of 2-7, and Co or Mn is contained in an amount of 0-2 wt.% expressed in terms of oxide. Further, the SiO<SB>2</SB>-B<SB>2</SB>O<SB>3</SB>-ZnO-R<SB>2</SB>O-CuO-based glass is characterized in that the coefficient of thermal expansion in a temperature range of 30-300°C is (65-95)×10<SP>-7</SP>/°C and the softening point is within a range of 500-600°C. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an insulating coating material for an electronic material substrate typified by a plasma display panel, a liquid crystal display panel, an electroluminescence panel, a fluorescent display panel, an electrochromic display panel, a light emitting diode display panel, a gas discharge display panel, and the like. The present invention relates to a low melting point glass used as a sealing material.

  With the recent development of electronic components, many types of display panels such as plasma display panels, liquid crystal display panels, electroluminescence panels, fluorescent display panels, electrochromic display panels, light emitting diode display panels, and gas discharge display panels have been developed. Has been. Among them, a plasma display panel (hereinafter abbreviated as PDP) is attracting attention as a thin and large flat color display device. In a PDP, a large number of cells are provided between a front substrate and a rear substrate used as a display surface, and an image is formed by performing plasma discharge in the cells. This cell is partitioned by partition walls, and an electrode is formed for each pixel unit in order to control the display state of each pixel forming an image.

  An electrode for discharging plasma is formed on the front glass plate of the plasma display panel, and thin linear silver is often used as the electrode. A highly transparent insulating material is disposed around the electrode. This insulating material is preferably excellent in plasma durability and transparent. For this reason, dielectric glass is often used as an insulating material. The dielectric glass is naturally required to have a melting point lower than that of the glass plate serving as the substrate in the process, and therefore low-melting glass is used.

  However, with conventional low melting point dielectric glass, firing at a low temperature of 450 to 600 ° C. causes a phenomenon that the dielectric glass reacts with the silver of the bus electrode and the dielectric glass is colored yellow (yellowing), resulting in high transmission. There was a big problem that the rate could not be obtained.

Regarding this yellowing, there are various known techniques to be solved by adjusting the glass component. A material for plasma display which contains SiO ₂ , Al ₂ O _3, etc. as essential components, for example, limits the contents of PbO and CuO and prevents silver diffusion by Cu (for example, see Patent Document 1), and CuO In addition to the above, the same effect can be obtained by further adding SrO, and a material for plasma display in which the content of BaO + SrO + MgO is limited (see, for example, Patent Document 2), and a material for plasma display in which the content of BaO + CaO + Bi ₂ O ₃ is limited ( For example, see Patent Document 3), and materials for plasma display (see, for example, Patent Document 4) with limited contents of SiO ₂ , B ₂ O ₃ , ZnO, Bi ₂ O ₃ , BaO, and Al ₂ O ₃ are disclosed. Has been.
JP 2001-52621 A JP 2001-80934 A JP 2001-48577 A JP 2003-226549 A

  The conventional dielectric glass (insulating material) has a problem that the glass and silver electrode react with each other to cause the dielectric layer to be colored yellow (yellowing), resulting in a decrease in visible light transmittance. It is difficult to respond to this yellowing phenomenon, and it has not yet been able to respond to the level desired by the market.

  Conventionally, lead glass has been employed for low melting glass, for example, low melting glass for coating a substrate. The lead component is an important component for lowering the melting point of glass, but it has a great adverse effect on the human body and the environment. In recent years, there is a tendency to avoid its use. Lead-free electronic materials such as PDP are being studied. Yes.

  That is, Japanese Patent Application Laid-Open Nos. 2001-52621, 2001-80934, and 2001-48577 show a considerable improvement against yellowing, but basically contain lead. There is a problem. Furthermore, JP 2003-226549 A does not contain lead, and a considerable improvement against yellowing is recognized, but as well as lead, it contains bismuth which has a tendency to be avoided from an environmental standpoint. Yes.

The present invention is a transparent insulating lead-free low melting point glass in which 7 to 20 SiO ₂ , 32 to 50 B ₂ O ₃ , 25 to 42 ZnO, R ₂ O (Li ₂ O + Na ₂ O + K ₂ O) by weight%. ) 7-20 is the RO (MgO + CaO + SrO + BaO) of _{0~10, SiO 2 -B 2 O 3} -ZnO-R 2 O-CuO system lead-free low-melting glass, which comprises a CuO 0.1 to 2 .

The lead-free low-melting glass as described above, wherein the weight ratio of B ₂ O ₃ / ZnO is 0.85 or more and 2 or less.

The lead-free low-melting glass is characterized in that the weight ratio of (B ₂ O ₃ + R ₂ O) / SiO ₂ is 2 or more and 7 or less.

  Further, the lead-free low-melting glass as described above, which contains 0 to 2 of Co and Mn as oxides by weight%.

Moreover, it is said lead-free low melting glass whose thermal expansion coefficient in 30 degreeC-300 degreeC is (65-95) * 10 < ^-7 > / degreeC, and a softening point is 500 degreeC or more and 600 degrees C or less.

  Furthermore, it is an electronic material substrate using the above lead-free low-melting glass.

  Still further, the present invention is a PDP panel using the above lead-free low melting point glass.

  According to the present invention, in an electronic substrate material typified by a plasma display panel, it is possible to obtain a lead-free low-melting-point glass composition that suppresses yellowing due to a silver reaction and has high visible light transmittance.

  In addition, since PbO is not substantially contained, there is no influence on the human body and the environment. Here, “substantially free of PbO” means an amount of PbO mixed as an impurity in the glass raw material. For example, if it is in the range of 0.3 wt% or less in the low-melting glass, there is almost no influence on the adverse effects described above, that is, the influence on the human body and the environment, the insulation characteristics, etc., and it is not substantially affected by PbO. Become.

The present invention is a transparent insulating lead-free low melting point glass in which 7 to 20 SiO ₂ , 32 to 50 B ₂ O ₃ , 25 to 42 ZnO, R ₂ O (Li ₂ O + Na ₂ O + K ₂ O) by weight%. ) 7-20 is the RO (MgO + CaO + SrO + BaO) of _{0~10, SiO 2 -B 2 O 3} -ZnO-R 2 O-CuO system lead-free low-melting glass, which comprises a CuO 0.1 to 2 .

SiO ₂ is a glass-forming component that can form a stable glass and is a component that controls fluidity during glass firing. If the amount is less than 7% (weight percent, the same applies to the following), the above-described effect cannot be exhibited. If it exceeds 20%, the softening point of the glass increases, and the formability and workability become difficult. More preferably, it is 9 to 18% of range.

B ₂ O ₃ is a glass-forming component similar to SiO ₂ , facilitates glass melting, suppresses an excessive increase in the thermal expansion coefficient of the glass, and imparts moderate fluidity to the glass during baking, together with SiO ₂ It decreases the dielectric constant. It is preferable to make it contain at 32 to 50% in glass. If it is less than 32%, the flowability of the glass becomes insufficient, and the sinterability is impaired. On the other hand, if it exceeds 50%, the stability of the glass is lowered. More preferably, it is 36 to 45% of range.

  ZnO lowers the softening point of the glass and adjusts the thermal expansion coefficient to an appropriate range, and is preferably contained in the glass in a range of 25 to 42%. If it is less than 25%, the above-mentioned action cannot be exhibited, while if it exceeds 42%, the glass becomes unstable and devitrification tends to occur. More preferably, it is 28 to 37% of range.

R ₂ O (Li ₂ O, Na ₂ O, K ₂ O) lowers the softening point of glass, imparts moderate fluidity, and adjusts the thermal expansion coefficient to an appropriate range, and is in the range of 7 to 20%. It is preferable to contain. If it is less than 7%, the above-mentioned action cannot be exhibited, and if it exceeds 20%, the thermal expansion coefficient is excessively increased. More preferably, it is 10 to 17% of range.

  CuO has the effect of relieving the silver electrode used as the bus electrode wire and the dielectric layer reacting to diffuse silver into the dielectric layer and causing silver colloid coloration (yellowing). It is preferable to make it contain in 2% of range. If it is less than 0.1%, the above effect cannot be exhibited, and if it exceeds 2%, the glass is colored and the transparency is lowered. More preferably, it is 0.1 to 1% of range.

Co and Mn oxides react with silver electrodes used as bus electrode wires for PDP panels and dielectric layers, and silver diffuses into the dielectric layers, causing silver colloid coloration (yellowing). It has an effect of mitigating and is preferably contained in a range of 0 to 2%. If it exceeds 2%, the glass is colored and the transparency is lowered. More preferably, it is 0 to 1% of range.
RO (MgO + CaO + SrO + BaO) imparts moderate fluidity to the glass and adjusts the thermal expansion coefficient to an appropriate range, and is contained in the range of 0 to 10%. If it exceeds 10%, the thermal expansion coefficient excessively increases. More preferably, it is 0 to 7% of range.

The weight ratio of B ₂ O ₃ / ZnO is preferably 0.85 or more and 2 or less. If it is less than 0.85, the yellowing is remarkably exhibited, and if it exceeds 2, the softening point becomes too high. More preferably, it is the range of 1.0-1.6.

The weight ratio of (B ₂ O ₃ + R ₂ O) / SiO ₂ is preferably 2 or more and 7 or less. If it is less than 2, the glass viscosity is high and sintering is insufficient, and if it exceeds 7, the fluidity becomes too high and the fluctuation of the transmittance becomes large. More preferably, it is the range of 4-6.

In addition, the total amount of In ₂ O ₃ , TiO ₂ , V ₂ O ₅ , Fe ₂ O ₃ , SnO ₂ , TeO _{2 and the} like represented by a general oxide is within a range that does not impair the object of the present invention. Up to 0.5%.

The thermal expansion coefficient at 30 ° C. to 300 ° C. is preferably (65 to 95) × 10 ⁻⁷ / ° C., and the softening point is preferably 500 ° C. or more and 600 ° C. or less. When the thermal expansion coefficient is outside (65 to 95) × 10 ⁻⁷ / ° C., problems such as peeling of the coating film and warping of the substrate occur when the thick film is formed. Preferably, it is in the range of (75 to 85) × 10 ⁻⁷ / ° C.

  If the softening point exceeds 600 ° C., problems such as softening deformation of the substrate occur. Preferably, they are 520 degreeC or more and 580 degrees C or less.

  Furthermore, it is a substrate for electronic materials using the low melting point glass. By using the low-melting glass described above, a substrate for electronic material in which yellowing is suppressed can be obtained.

  Furthermore, the present invention is a PDP panel using the above-mentioned low melting point glass. By using the low melting point glass described above, a PDP panel in which yellowing is suppressed can be obtained.

  Although the present invention is preferable as a low melting point glass corresponding to the yellowing phenomenon due to the reaction with silver, the object of use is not limited to the insulating material around the silver electrode.

  The lead-free low-melting glass of the present invention can be used, for example, on the front plate or the back plate of PDP glass. When used as a back plate, it is used as a sealing material or a covering material, and is often used after being powdered. This powdered glass is mixed with a low expansion ceramic filler represented by mullite or alumina, a heat-resistant pigment, etc. at a ratio of 0.6 {glass / (glass + filler) weight ratio} or more, and then organically. Generally, it is kneaded with oil to form a paste.

  As the glass substrate, a transparent glass substrate, particularly soda-lime-silica glass, or similar glass (high strain point glass), or an alumino-lime borosilicate glass with little (or almost no) alkali content is used. Yes.

  Hereinafter, a description will be given based on examples.

(Production of low melting point glass mixed paste)
The fine silica sand as a SiO _{2 source,} a boric acid as a B 2 _{O 3} source, a zinc oxide as a ZnO source, lithium carbonate as Li ₂ O source, sodium carbonate as Na ₂ O source, potassium carbonate as _{K 2} O source Further, cupric oxide was required as the CuO source, manganese dioxide as the MnO ₂ source, magnesium carbonate as the MgO source, calcium carbonate as the CaO source, strontium carbonate as the SrO source, and barium carbonate as the BaO source. After preparing these as a desired low melting glass composition, it puts into a platinum crucible and heat-melts in 1000-1300 degreeC and 1-2 hours in an electric heating furnace, Examples 1-6 of Table 1, Table 1 The glass of the composition shown in 2 comparative examples 1-6 was obtained.

  A part of the glass was poured into a mold, made into a block shape, and used for measurement of thermal properties (thermal expansion coefficient, softening point). The remaining glass was formed into flakes with a rapid cooling twin roll molding machine and sized with a pulverizer into a powder having an average particle size of 1 to 3 μm and a maximum particle size of less than 10 μm.

  Next, paste oil composed of α-terpineol and butyl carbitol acetate was mixed with ethyl cellulose as a binder and the above glass powder to prepare a paste having a viscosity of about 300 ± 50 poise.

(Formation of insulating coating)
The paste was applied using an applicator to a soda-lime glass substrate having a thickness of 2 to 3 mm and a size of 100 mm square so that the film thickness after baking was about 20 μm, thereby forming an application layer.

  Next, after drying, a clear dielectric layer was formed by firing at 600 ° C. or lower for 10 to 60 minutes.

  The obtained sample was observed with the naked eye and a microscope, and it was judged that the yellowing phenomenon was markedly suppressed as compared with the conventional sample, and the others were marked with x.

  Regarding the variation in transmittance, the transmittance (550 nm) variation when the firing temperature was varied by 30 ° C. was 4% or less, and the others were evaluated as x.

The softening point was the temperature when the viscosity coefficient η = 10 ^7.6 was reached using a Littleton viscometer. Moreover, the thermal expansion coefficient was calculated | required from the amount of elongation at 30-300 degreeC when it heated up at 5 degree-C / min using the thermal dilatometer.

(result)
The low melting point glass composition and various test results are shown in the table.

  As shown in Examples 1 to 6 in Table 1, within the composition range of the present invention, the occurrence of yellowing was significantly suppressed as compared with the conventional case.

  On the other hand, Comparative Examples 1 to 6 in Table 2 outside the compositional range of the present invention show remarkable yellowing as in the prior art, or do not show preferable physical properties, and low melting point glass for substrate coating such as PDP. As inapplicable.

Claims (7)

7 in the transparent insulating lead-free low-melting-point glass, SiO ₂ 7-20 _weight%, B 2 _{O 3} and 32-50, the ZnO 25 to _42, R 2 O and _{(Li 2 O + Na 2 O} + K 2 O) 20. A SiO ₂ —B ₂ O ₃ —ZnO—R ₂ O—CuO-based lead-free low-melting glass characterized by containing 0.1 to 2 CuO and 0 to 10 RO (MgO + CaO + SrO + BaO). The lead-free low-melting glass according to claim 1, wherein the weight ratio of B ₂ O ₃ / ZnO is 0.85 or more and 2 or less. The lead-free low-melting glass according to claim 1 or _{2, wherein} a weight ratio of (B ₂ O ₃ + R ₂ O) / SiO ₂ is 2 or more and 7 or less. The lead-free low-melting glass according to any one of claims 1 to 3, wherein the lead-free low-melting glass contains Co or Mn as an oxide in an amount of 0 to 2% by weight. The lead-free lead according to any one of claims 1 to 4, wherein the coefficient of thermal expansion at 30 to 300 ° C is (65 to 95) x 10 ^-7 / ° C, and the softening point is 500 to 600 ° C. Low melting glass. 6. A substrate for electronic materials, wherein the lead-free low-melting glass according to claim 1 is used. 6. A PDP panel using the lead-free low-melting glass according to claim 1.