JP4972946B2 - Substrate glass for display devices - Google Patents

Description

  The present invention relates to a glass composition having excellent heat resistance and durability. For example, the present invention relates to a substrate glass for a display device suitable as a substrate glass for a flat panel display device such as a plasma display panel (PDP), a field emission display (FED), or a liquid crystal display (LCD).

  Conventionally, high strain point glass has been used in the PDP manufacturing field, and alkali-free glass has been used in the LCD manufacturing field.

  For example, in the PDP manufacturing field, alkali / alkaline earth / silica glass similar to soda lime silica glass is used, which has a thermal expansion coefficient close to that of soda lime silica glass and a strain point exceeding 550 ° C. Or high strain point glass exceeding 600 ° C. (see Patent Documents 1 to 3). Substrates using these glasses have a problem in that the thermal expansion coefficient is close to that of soda lime silica glass in the manufacturing process of the display panel, so that the thermal contraction is large and the thermal deformation is large in the panel manufacturing process.

On the other hand, in the LCD manufacturing field, alkali-free glass containing no alkali metal oxide is used. This is because it dislikes the movement of alkali ions from the glass to the electrode side during various heat treatments during the LCD manufacturing process. Since the substrate using such glass has a small average linear expansion coefficient at 30 to 300 ° C. of 40 × 10 ⁻⁷ / ° C. or less and a high strain point of 640 ° C. or more in the display panel manufacturing process, the heat shrinkage is caused. Is small (see Patent Documents 4 and 5).
Japanese Patent Laid-Open No. 10-045423 Japanese Patent Application Laid-Open No. 11-240735 JP 2000-103638 A JP 2002-029776 A JP 2002-308643 A

  The high strain point glass described in, for example, JP-A-10-045423, JP-A-11-240735, JP-A-2000-103638, etc. has a thermal expansion coefficient of soda lime silica in the display panel manufacturing process. Since it is close to glass, there is a problem that thermal shrinkage is large and thermal deformation is large in the panel manufacturing process.

  In addition, so-called alkali-free glass described in JP-A-2002-029776, JP-A-2002-308643 and the like does not contain an alkali metal oxide, so that the melting temperature is 1590 ° C. or higher. Is mainly produced by the fusion method, and there is a problem that productivity is poor.

  In order to eliminate the above problems, the glass of the present invention is a glass having a thermal expansion coefficient lower than that of the high strain point glass and higher than that of the alkali-free glass. The substrate using this glass in the PDP manufacturing process has a low thermal expansion coefficient, so that there is little thermal deformation, and the thermal expansion consistency with other members constituting the panel is not a big problem. Further, since the strain point is 615 ° C. or higher, which is higher than 580 ° C. of the conventional high strain point glass, the substrate is less likely to warp or shrink than the conventional glass when performing various heat treatments in the display panel manufacturing process.

  On the other hand, even when this glass is used in the LCD manufacturing process, the substrate is not easily warped or contracted for the same reason as described above, and alkali ions are less likely to elute so that the movement of alkali ions during heat treatment is suppressed. Is done. The most important issue for LCD industry is how large glass substrates can be handled in terms of cost, but the glass of the present invention has a melting temperature comparable to that of conventional high strain point glass and is suitable for manufacturing by the FL method. High productivity and easy area enlargement.

  From the above, the glass of the present invention can improve the problems of the high strain point glass substrate and the non-alkali glass substrate, respectively, and has intermediate characteristics, so that it can be used for both.

The present invention is substantially expressed by weight%, SiO ₂ is 52 to 59, Al ₂ O ₃ is 3 to 12, Na ₂ O is 2.0 to 3.5, and K ₂ O is 0.3 to 1. 5, R ₂ O (where R is Li, Na, K) is 2.5 to 4, Na ₂ O / R ₂ O is 0.55 to 0.88, MgO is 3 to 5.5, and CaO is 4 to 8, SrO is 5 to 11, BaO is 9 to 17, R'O (provided that, R 'is Mg, Ca, Sr, Ba) is 25 to 32, ZrO ₂ is for a display apparatus is from 1 to 4.5 It is substrate glass.

Moreover, it is said substrate glass for display apparatuses characterized by the average linear expansion coefficient in 30-300 degreeC being (60-65) * 10 < ^-7 > / degreeC.

  Moreover, it is said substrate glass for display apparatuses characterized by a strain point being 615 degreeC or more.

  Moreover, it is said substrate glass for display apparatuses characterized by having a Young's modulus of 78 to 88 GPa.

Further, the substrate glass for a display device described above, wherein the fracture toughness K _IC is 0.6 MPa · m ^1/2 or more.

Moreover, it is said substrate glass for display apparatuses characterized by a density being 3.0 g / cm < ³ > or less.

  The above-mentioned substrate glass for a display device is characterized in that the melting temperature (temperature (° C.) when the viscosity is log η = 2.0) is 1535 ° C. or less.

Furthermore, in the alkali elution test of the JIS R 3502 standard, the alkali elution amount converted to Na ₂ O is 0.01 (mg / 50 mL) or less.

  According to the present invention, since a glass substrate having an intermediate property between a high strain point glass substrate and a non-alkali glass substrate can be obtained, both problems can be improved and a glass substrate that can be used for both can be obtained. Can be obtained.

In the present invention, the thermal expansion coefficient and strain point are characteristics indicating the heat resistance of glass. If the thermal expansion coefficient exceeds 65 × 10 ⁻⁷ / ° C., thermal deformation becomes too large in the display panel manufacturing process, which is not suitable. It is. Therefore, 65 × 10 ⁻⁷ / ° C. or less is appropriate. In addition, if the strain point is low, thermal deformation becomes excessive in the display panel manufacturing process, so 615 ° C. or higher is appropriate.

In the present invention, the fracture toughness K _IC is preferably 0.6 MPa · m ^1/2 or more, and the Young's modulus is preferably 78 to 88 GPa. These characteristics are related to the fragility of the glass. Outside these ranges, there is a problem that the glass is easily broken during the manufacturing process of the display device.

In the present invention, the density is desirably 3.0 g / cm ³ or less. If the density exceeds 3.0 g · cm ³ , the display device cannot be reduced in weight.

  In the present invention, the melting temperature (temperature (° C.) when the viscosity is log η = 2.0) is preferably 1535 ° C. or less. This is because the melting temperature is related to the ease of molding of the glass substrate, and if it exceeds 1535 ° C., molding is difficult, or molding means with poor productivity such as a fusion method is required.

  Furthermore, in the present invention, the amount of alkali elution is a characteristic indicating the durability of glass, and when it increases, the substrate deteriorates within the production process. Therefore, it is 0.01 mg / 50 mL or less.

In the component system of the present invention, SiO ₂ is a main component of glass, and if it is less than 52% by weight, the heat resistance or chemical durability of the glass is deteriorated. On the other hand, if it exceeds 59%, the high-temperature viscosity of the glass melt becomes high and glass molding becomes difficult. Moreover, the linear expansion coefficient of glass becomes too small, and the compatibility with other members constituting the display panel is deteriorated. Therefore, the range is 52 to 59%, preferably 52 to 56%.

Al ₂ O ₃ is a component that increases the strain point and decreases the density. If the weight percentage is less than 3%, the heat resistance or chemical durability of the glass deteriorates. On the other hand, if it exceeds 12%, the tendency of devitrification of the glass becomes large, and it becomes difficult to mold molten glass. Therefore, it is 3 to 12% of range.

Na ₂ O acts as a flux at the time of glass melting together with K ₂ O. If the weight percentage is less than 2.0%, the high-temperature viscosity of the glass melt increases and glass molding becomes difficult. On the other hand, if it exceeds 3.5%, the thermal expansion coefficient becomes large. Therefore, the range is 2.0 to 3.5%.

K ₂ O exhibits the same effect as Na ₂ O. If the weight percent is less than 0.3%, the high-temperature viscosity of the glass melt becomes high and glass molding becomes difficult. On the other hand, if it exceeds 1.5%, the thermal expansion coefficient increases. Therefore, the range is 0.3 to 1.5%.

With respect to the amount of the alkali component (Na ₂ O, K ₂ O), the linear thermal expansion coefficient, the high temperature viscosity, and the devitrification temperature are within appropriate ranges by setting the total amount to _2.5 to 4% by weight. Can be maintained. If the total amount of the alkali components is less than 2.5%, the high-temperature viscosity of the glass melt becomes high, and glass molding becomes difficult. Further, the tendency of glass to devitrify increases. If it exceeds 4%, the thermal expansion coefficient increases excessively. Therefore, the range is 2.5 to 4%.

  MgO has the effect | action which lowers | hangs the viscosity of the molten glass at the time of glass melting. If the weight percentage is less than 3%, the high-temperature viscosity of the glass melt increases and glass molding becomes difficult. On the other hand, if it exceeds 5.5%, the tendency of devitrification of the glass increases and it becomes difficult to mold the molten glass. Therefore, the range is 3 to 5.5%.

  CaO has the effect of lowering the viscosity of the molten glass at the time of melting the glass and the effect of increasing the thermal expansion coefficient of the glass. If the weight percentage is less than 4%, the thermal expansion coefficient of the glass is too low. On the other hand, if it exceeds 8%, the tendency of devitrification increases, and it becomes difficult to mold molten glass. Therefore, the range is 4 to 8%.

  SrO is not an essential component, but has the effect of suppressing the occurrence of devitrification by lowering the high-temperature viscosity of the glass melt in the presence of CaO. If the weight percentage is less than 5%, the high-temperature viscosity of the glass melt increases and glass molding becomes difficult. On the other hand, if it exceeds 11%, the density becomes too high, so a range of 5 to 11% or less is desirable.

  BaO is not an essential component, but has the effect of suppressing the devitrification tendency of the glass melt and has the effect of lowering the Young's modulus. If the weight percentage is less than 9%, the tendency of the glass to devitrify becomes large, and it becomes difficult to mold the molten glass. Since density will rise when it exceeds 17%, the range of 9-17% or less is desirable.

  Further, within the above composition range, the total amount of the divalent metal oxide RO (R is Mg, Ca, Sr, Ba) is in the range of 25 to 32% by weight%, thereby improving the meltability of the glass. While maintaining in a good range, a glass having a suitable viscosity-temperature gradient and good glass moldability, excellent heat resistance, chemical durability and the like, and having an appropriate range of thermal expansion coefficient can be obtained. If the total RO is less than 25%, the high-temperature viscosity increases and it becomes difficult to melt and mold the glass. In addition, the strain point is lowered too much and the thermal expansion coefficient is lowered. On the other hand, if it exceeds 32%, the density increases, the tendency to devitrification increases, and the chemical durability decreases. A more preferable range is 27 to 31%.

ZrO ₂ has the effect of increasing the strain point of the glass and improving the chemical durability of the glass. If the weight percentage is less than 1%, the strain point of the glass cannot maintain the desired range. If it exceeds 4.5%, the density increases, and any desired value cannot be maintained. Therefore, it is 1 to 4.5%, preferably 1 to 4.5%.

The glass of the preferred embodiment of the present invention consists essentially of the above components, but may contain other components in a total amount of up to 1% by weight within a range not impairing the object of the present invention. For example, a total amount of SO ₃ , Cl, F, As ₂ O _{3 and the} like may be contained up to 1% in order to improve melting, fining, and moldability of glass. Further, _Fe 2 _O 3 to color the glass, CoO, may contain NiO, etc. up to 1% in total. Further, in order to prevent electron beam browning in the PDP, TiO ₂ and CeO ₂ may each be contained up to 1%, and the total amount may be contained up to 1%.

  Hereinafter, an example explains.

  A prepared raw material consisting of silica sand, aluminum oxide, sodium carbonate, sodium sulfate, potassium carbonate, magnesium oxide, calcium carbonate, strontium carbonate, barium carbonate and zirconium silicate is filled in a platinum crucible, and 1500-1600 ° C., about 6 in an electric furnace. It was melted by heating for hours. During the heating and melting, the glass melt was stirred with a platinum rod to homogenize the glass.

  Next, the molten glass was poured into a mold to form a glass block, which was transferred to an electric furnace maintained at 550 to 650 ° C. and gradually cooled in the furnace. The obtained glass sample was homogeneous without bubbles or striae.

Table 1 shows the glass composition (as oxide) based on the raw material formulation. For these glasses, an average linear expansion coefficient (10 ⁻⁷ / ° C.) of 30 to 300 ° C., melting temperature / working temperature (° C.), strain point (° C.), density (g / cm ³ ), Young's modulus (GPa) The fracture toughness K _IC (MPa · m ^1/2 ) and the alkali elution amount (mg) were measured by the following methods.

  The expansion coefficient measured the average linear expansion coefficient in 30-300 degreeC using the thermomechanical analyzer TMA8310 (Rigaku Denki Co., Ltd. product). Melting temperature and working temperature were measured by a ball pulling method using a ball pulling viscometer (manufactured by Opto Corporation), with log η = 2.0 and 4.0 as melt temperature and working temperature, respectively. The strain point was measured by a beam bending method based on JIS R3103-2. The density was measured by the Archimedes method using glass without bubbles (about 50 g). The Young's modulus was measured using a single-around type acoustic wave measuring device UVM-2 (manufactured by Ultrasonic Industry Co., Ltd.). Fracture toughness was calculated by a fine ceramic fracture toughness test method (indentation press-in method) described in JIS R 1607 using a microhardness tester HM (manufactured by Akashi Co., Ltd.). The alkali elution amount was measured by an alkali elution test method described in JIS R 3502.

(result)
Examples 1 to 6 in Table 1 and Examples 7 to 11 in Table 2 are glasses in the present invention, and Comparative Example 1 in Table 3 is soda lime silica glass. Comparative Examples 2 and 3 are conventional high strain point glasses, and Comparative Example 4 is a conventional alkali-free glass.

In the soda-lime silica glass of Comparative Example 1 and the high strain point glasses of Comparative Examples 2 and 3, the density, Young's modulus, and fracture toughness are appropriate values, but the thermal expansion coefficients are all 65 × 10 ⁻⁷ / ° C. The amount of alkali elution is greater than 0.01 mg. Further, in the alkali-free glass of Comparative Example 4, although the density and strain point are appropriate values, the thermal expansion coefficient is 60 × 10 ⁻⁷ / ° C. or lower, and the melting temperature is 1590 ° C. or higher.

On the other hand, the glasses of Examples 1 to 11 have a thermal expansion coefficient in the range of 60 to 65 × 10 ⁻⁷ / ° C., and also have a density, strain point, melting temperature, fracture toughness value, Young's modulus and alkali. The elution amount is a desired value. Accordingly, the glass of the present invention has the same density, strain point, fracture toughness value and Young's modulus as the conventional high strain point glass, and has a lower thermal expansion coefficient than the high strain point glass. As compared with the strain point glass, it is obvious that the thermal deformation of the glass substrate in the heat treatment process in the display panel manufacturing process is small and the generation of thermal stress is small.

  Compared to conventional alkali-free glass, the thermal deformation of the glass substrate in the heat treatment process in the display panel manufacturing process is comparable, and alkali ions are less likely to elute and can be manufactured by the FL method, improving productivity. However, it is obvious that the area can be easily increased.

  The present invention can be used not only for conventional display panel applications such as PDP and LCD, but also in the entire electronic material field requiring a heat treatment process.

Claims (8)

Substantially expressed by weight%, SiO ₂ is 52 to 59, Al ₂ O ₃ is 3 to 12, Na ₂ O is 2.0 to 3.5, K ₂ O is 0.3 to 1.5, R ₂ O (wherein, R is Li, Na, K) is _{2.5~4, Na 2 O / R 2} O is from 0.55 to .88, MgO is 3 to 5.5, CaO is 4 to 8, SrO 5 to 11, BaO 9 to 17, R′O (where R ′ is Mg, Ca, Sr, Ba) 25 to 32, and ZrO _{2 1} to 4.5. The average linear expansion coefficient in 30-300 degreeC is (60-65) * 10 < ^-7 > / degreeC, The substrate glass for display apparatuses of Claim 1 characterized by the above-mentioned. 3. The substrate glass for a display device according to claim 1, wherein the strain point is 615 [deg.] C. or higher. The substrate glass for a display device according to any one of claims 1 to 3 , wherein the Young's modulus is 78 to 88 GPa. The substrate glass for a display device according to any one of claims 1 to 4 , wherein the fracture toughness K _IC is 0.6 MPa · m ^1/2 or more. The substrate glass for a display device according to any one of claims 1 to 5, wherein a density is 3.0 g / cm ³ or less. Melting temperature (temperature at the viscosity logη = 2.0 (℃)) is a display device substrate glass according to any one of claims 1 to 6, wherein not more than 1535 ° C.. The substrate for display device according to any one of claims 1 to 7 , wherein an alkali elution amount converted to Na ₂ O is 0.01 (mg / 50 mL) or less in an alkali elution test of JIS R 3502 standard. Glass.