JP2006096594A - Substrate glass for display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide substrate glass for a flat panel display device having a high strain point, high heat resistance, high toughness and a low density. <P>SOLUTION: The substrate glass substantially comprises, in wt.%, 63-69 SiO<SB>2</SB>, 0.5-5 Al<SB>2</SB>O<SB>3</SB>, 2-7 Na<SB>2</SB>O, 14-17 K<SB>2</SB>O, 10-18 MgO, 0-7 CaO, 0-3 SrO, 0-3 BaO and 0.5-7 ZrO<SB>2</SB>, and has ≥570°C strain point, (86-90)×10<SP>-7</SP>/°C average linear thermal expansion coefficient at 30-300°C, ≥0.7 MPa×m<SP>1/2</SP>fracture toughness K<SB>IC</SB>and <2.6 g/cm<SP>3</SP>density. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a glass composition having excellent heat resistance, light weight and high strength. In particular, glass substrates that require the same thermal expansion coefficient and high heat resistance as ordinary soda lime silica glass, such as electronic displays such as PDP (plasma display panel), EL (electroluminescence), and FED (field emission display). The present invention relates to a glass composition suitable for an industrial substrate.

Conventionally, in the PDP manufacturing field, soda lime silica glass having a thermal expansion coefficient of about 80 to 90 × 10 ⁻⁷ / ° C. and a strain point of about 510 to 520 ° C. has been used as a substrate glass. Soda lime silica glass is used in many fields and is advantageous in that it can be easily procured at a low price. However, since the strain point is low, the electrode glass pattern is arranged on the glass substrate, and the insulation coating with low melting point glass is formed. The problem that it is easy to occur arises.

In order to solve the above problems, in recent years, alkali lime glass similar to soda lime silica glass has a thermal expansion coefficient close to that of soda lime silica glass, and its strain point exceeds 550 ° C or 600 ° C. High-strain-point glass has been proposed (for example, Patent Documents 1 to 3). These glasses are less likely to be thermally deformed in the manufacturing process of the display panel and have good expansion consistency with other members.
Japanese Patent No. 2738036 JP-A-9-202641 JP-A-9-255354

    However, the conventional high strain point glass has a composition slightly different from that of soda lime silica glass, and the density of the conventional high strain point glass is heavier than that of soda lime silica glass and exceeds 2.6. There are many things. This has a problem that it is difficult to reduce the weight of the display device, and also causes a problem of deflection due to the weight of the glass substrate. That is, the amount of deflection (W) due to the weight of the glass substrate increases in proportion to the density (ρ) of the glass as represented by the formula (1). For this reason, when the glass substrate is increased in size, the amount of deflection becomes larger, and there is a problem that problems such as breakage occur in the process of transporting and moving the substrate.

W = c (ρ / E) (L ⁴ / t ² ) (1)
W: Maximum deflection, L: Distance between two side supports, t: Plate thickness, ρ: Glass density, E: Young's modulus of glass, c: Constant Further, conventional high strain point glass is made of soda lime silica glass Since they are more fragile, there is a problem that they are easily broken when various treatments are performed. Generally, glass cracking is considered to be brittle fracture starting from scratches, and resistance to this fracture is called fracture toughness (K _IC ). Therefore, a glass with a high K _IC is required to improve the cracking problem.
In order to solve these problems, an object of the present invention is to provide a glass substrate composition characterized by having a linear expansion coefficient comparable to that of soda lime silica glass, a high strain point, a high K _IC , and a low density. Is to provide.

The present invention is substantially expressed by weight%, SiO ₂ is 63 to 69, Al ₂ O ₃ is 0.5 to 5, Na ₂ O is 2 to 7, K ₂ O is 14 to 17, and MgO is 10 to 10. 18. For a flat panel display device characterized in that CaO is 0 to 7, SrO is 0 to 3, BaO is 0 to 3, ZrO ₂ is 0.5 to 7, and the strain point is 570 ° C. or higher. It is substrate glass.

Moreover, it is said substrate glass for flat panel display apparatuses characterized by the average linear thermal expansion coefficient in 30 degreeC-300 degreeC being (86-90) x10 < ^-7 > / degreeC.

Furthermore, it is said substrate glass for flat panel display apparatuses characterized by fracture toughness K _IC being 0.7 MPa · m ^1/2 or more.

Furthermore, the substrate glass for a flat panel display device described above, wherein the density is less than 2.6 g / cm ³ .

According to the present invention, a high strain point glass having a thermal expansion coefficient comparable to that of ordinary soda lime silica glass, low density, and high fracture toughness K _IC can be provided, such as PDP, EL and FED. It is extremely suitable as a glass substrate for electronic displays.

Substantially expressed by weight%, SiO ₂ is 63 to 69, Al ₂ O ₃ is 0.5 to 5, Na ₂ O is 2 to 7, K ₂ O is 14 to 17, MgO is 10 to 18, CaO is A substrate glass for a flat panel display device comprising 0 to 7, SrO of 0 to 3, BaO of 0 to 3, ZrO ₂ of 0.5 to 7, and a strain point of 570 ° C. or higher. .

SiO ₂ is a main component of glass, and if it is less than 63% by weight, the desired fracture toughness K _IC cannot be obtained, and the heat resistance or chemical durability of the glass is deteriorated. On the other hand, if it exceeds 69%, the high-temperature viscosity of the glass melt increases, and glass molding becomes difficult. Moreover, the linear thermal expansion coefficient of glass becomes too small, and compatibility with other members constituting the display panel is deteriorated. Therefore, the range is 63 to 69%, preferably 64 to 68%.

Al ₂ O ₃ is a component that increases the strain point and fracture toughness K _IC and is an essential component. If the weight percentage is less than 0.5%, the glass strain point and fracture toughness K _IC will decrease. On the other hand, if it exceeds 5%, the high-temperature viscosity of the glass melt will increase and the tendency to devitrification will increase. It becomes difficult. Therefore, the range of 0.5 to 5%, preferably 1 to 4% is preferable.

Na ₂ O acts as a flux at the time of glass melting together with K ₂ O, and is indispensable for maintaining the linear expansion coefficient of the glass at an appropriate size. If it is less than 2%, the effect as a flux is insufficient, and the linear expansion coefficient becomes too low. If it exceeds 7%, the strain point is too low. Therefore, the range is 2 to 7%, preferably 3 to 6%.

K 2 _O is, with shows the same effect as Na 2 _O, and suppress the movement of the alkali ions by mixed alkali effect with Na 2 _O, it is an essential component to improve the volume resistivity of the glass. If it is less than 14%, the action thereof is insufficient, and if it exceeds 17%, the linear expansion coefficient is excessive and the strain point is excessively lowered. Therefore, the range of 14-17%, preferably 15-17% And

MgO is an essential component that can increase the fracture toughness K _IC of the glass and increase the strain point. If it is less than 10%, their action is insufficient. On the other hand, if it exceeds 18%, the tendency of devitrification becomes large, so that it becomes difficult to form glass. Accordingly, the range is 10 to 18%, preferably 10.5 to 16%.

CaO is not an essential component, but has an effect of lowering the viscosity of the molten glass at the time of melting the glass and an effect of raising the strain point of the glass. Therefore, you may contain to 7% or less. If it exceeds 7%, the hardness of the glass is raised and the fracture toughness K _IC is lowered. Therefore, it is desirably introduced in a range of 7% or less.

  SrO and BaO are not essential components, but have the effect of suppressing the occurrence of devitrification by lowering the high-temperature viscosity of the glass melt in the presence of CaO. If it exceeds 3%, the coefficient of linear expansion becomes excessive, so a range of 3% or less is desirable.

ZrO ₂ is an essential component that has the effect of raising the strain point of glass and improving the chemical durability of glass, and is preferably contained in an amount of 0.5% or more. If it exceeds 7%, the density increases and the desired value cannot be maintained. Accordingly, the range is 0.5 to 7%, preferably 1 to 6%.

B ₂ O ₃ is not an essential component, but may have an effect of lowering the viscosity of the molten glass at the time of melting the glass and may be contained up to 5% in order to have an effect of reducing the tendency to devitrification. If it exceeds 5%, the strain point becomes too low, so it is desirable to introduce it in the range of 5% or less.

Li ₂ O is not an essential component, but lowers the high temperature viscosity of the glass and promotes melting of the glass raw material. However, if the content exceeds 3%, the strain point is excessively lowered, so it is desirable to introduce it in a range of 3% or less.

Although the glass of the preferable aspect of this invention consists of the said component substantially, in the range which does not impair the objective of this invention, you may contain other components to 3% in a total amount by weight% display. 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%.

  When the strain point is less than 570 ° C., deformation of the substrate glass, such as warping and shrinkage, is performed when various heat treatments are performed on the panel production, such as arranging an electrode line pattern on the glass substrate and further forming an insulating coating with low-melting glass. The problem that it is easy to produce occurs.

Moreover, it is said substrate glass for flat panel display apparatuses characterized by the average linear thermal expansion coefficient in 30 degreeC-300 degreeC being (86-90) x10 < ^-7 > / degreeC. When the average linear thermal expansion coefficient is out of (86 to 90) × 10 ⁻⁷ / ° C., the compatibility with other members constituting the display panel is deteriorated.

In particular, it is more desirable that the average linear thermal expansion coefficient of soda lime silica glass generally produced by the float process is approximately (87 to 88) × 10 ⁻⁷ / ° C.

Furthermore, it is said substrate glass for flat panel display apparatuses characterized by fracture toughness K _IC being 0.7 MPa · m ^1/2 or more. When the fracture toughness K _IC is less than 0.7 MPa · m ^1/2, there is a problem that it is easily broken during the manufacturing process of the display device.

Furthermore, the substrate glass for a flat panel display device described above, wherein the density is less than 2.6 g / cm ³ . When the density is 2.6 g / cm ³ or more, the value becomes larger than that of general soda lime silica glass, and when the display device is increased in size, there is a risk of causing problems such as deformation and cracking due to the weight of the glass substrate. .

  Hereinafter, a description will be given based on examples.

(Creation of glass)
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 charged into 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, transferred to an electric furnace maintained at 600 to 700 ° C. for cooling, and cooled in the furnace. Examples 1 to 5 in Table 1 and Comparative Example 1 in Table 2 A glass having the composition shown in -4 was obtained. The obtained glass sample was homogeneous without bubbles or striae.

For these glasses, the strain point (° C.), average linear thermal expansion coefficient (10 ⁻⁷ / ° C.), fracture toughness K _IC (MPa · m ^1/2 ) and density (g / cm ³ ) were measured by the following methods. did.

  The strain point was measured by a beam bending method based on JIS R3103-2. For the linear thermal expansion coefficient, an average linear thermal expansion coefficient at 30 to 300 ° C. was measured using a thermomechanical analyzer TMA8310 (manufactured by Rigaku Corporation). Fracture toughness was calculated by a fine ceramic fracture toughness test method (indentation press-in method) described in JIS R 1607 using a microhardness meter DMH-2 (manufactured by Matsuzawa Seiki Co., Ltd.). The density was measured by Archimedes method on glass without bubbles (about 50 g).

(result)
Examples 1 to 5 in Table 1 are glasses in the present invention, and Comparative Example 1 is soda lime silica glass. Comparative Examples 2 to 4 are conventional high strain point glasses. In the soda lime silica glass of Comparative Example 1, the density is less than 2.6 and the fracture toughness K _IC is 0.7 MPa · m ^1/2 , but the strain point is the same as that of the high strain point glasses of Comparative Examples 2 to 4. It shows that it is significantly lower than that. On the other hand, in the high strain point glasses of Comparative Examples 2 to 4, although the strain point is as high as 580 ° C. or higher, the density exceeds 2.6 and the fracture toughness K _IC is less than 0.7 MPa · m ^1/2 . It shows that there is.

In contrast, the glasses of Examples 1 to 5 have a sufficiently high strain point of 570 ° C. or higher, a density of less than 2.6, and a fracture toughness K _{IC of} over 0.75 MPa · m ^1/2. , 0.7 MPa · m ^1/2 or more is sufficiently satisfied. Therefore, it is clear that the glass of the present invention has a linear expansion coefficient equivalent to that of soda lime silica glass, heat resistance equivalent to that of a conventional high strain point glass, and low density and high fracture toughness. is there.

Claims (4)

Substantially expressed by weight%, SiO ₂ is 63 to 69, Al ₂ O ₃ is 0.5 to 5, Na ₂ O is 2 to 7, K ₂ O is 14 to 17, MgO is 10 to 18, CaO is A substrate glass for a flat panel display device comprising 0 to 7, SrO of 0 to 3, BaO of 0 to 3, ZrO ₂ of 0.5 to 7, and a strain point of 570 ° C or higher. 2. The substrate glass for a flat panel display device according to claim 1, wherein an average linear thermal expansion coefficient at 30 ° C. to 300 ° C. is (86 to 90) × 10 ⁻⁷ / ° C. 3. The substrate glass for flat panel display devices according to claim 1, wherein the fracture toughness K _IC is 0.7 MPa · m ^1/2 or more. The substrate glass for a flat panel display device according to any one of claims 1 to ^{3, wherein the} density is less than 2.6 g / cm ³ .