JP2008030978A - Setter for heat treatment of glass substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a setter for heat treatment of a glass substrate, which is hardly warped and deformed even if it is repeatedly used in the temperature range in which the glass substrate is heat treated. <P>SOLUTION: The setter for heat treatment of the glass substrate is formed from a plate-like crystallized glass and mounts the glass substrate on one surface thereof for heat treating the substrate. The crystallized glass contains 0.8-4 mass% K<SB>2</SB>O and 0.5-4 mass% Na<SB>2</SB>O. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a setter for heat treatment of a large glass substrate, and in particular, a flat plate for placing a large glass substrate used for a plasma display panel (hereinafter referred to as PDP) or the like directly on a placement surface and introducing it into a heating furnace. The present invention relates to a setter for heat treatment of a glass substrate.

  In recent years, with the diversification of display devices, large-screen flat displays are becoming the mainstream of display devices in place of CRTs. The typical PDP has two glass substrates facing each other on the front and back, both glass substrates on the top and bottom, and a 100-150 μm cell sandwiched between the sides. Characters and images are displayed by discharging gas by applying a gas containment voltage, which is characterized by being thinner than the size of the display screen. For example, a PDP module having a 42-inch display screen is a rectangular panel having a length of about 520 mm, a width of 920 mm, and a depth of about 50 mm.

  As a glass substrate for PDP, flat soda-lime glass or high strain point glass having a thickness of less than 3 mm is generally used, and a paste is used to form electrodes, dielectrics, phosphors, etc. on the glass substrate. Applied. In order to fix the applied paste to the glass substrate, the glass substrate is placed on a heat treatment setter and subjected to heat treatment in a temperature range of 450 to 650 ° C. in a heating furnace such as a roller hearth kiln.

As the setter for heat treatment of the glass substrate, for example, SiO ₂ , Al ₂ O ₃ , Li ₂ O, P ₂ O ₅ , TiO ₂ , ZrO ₂ are the main components, and the thermal expansion coefficient is 15 × 10 ⁻⁷ / K or less. A setter is disclosed which is made of crystallized glass, the flatness of the mounting surface is 0.3% or less, and the surface roughness of the mounting surface is in the range of 0.1 to 1 μm in Ra value ( For example, see Patent Document 1.)

As another setter for heat treatment, it is composed of a Li ₂ O—Al ₂ O ₃ —SiO ₂ crystallized glass plate containing a β-spodumene solid solution as a crystal phase, and the surface area of the surface on which the glass substrate is placed has a surface area of 14000 cm ^2. The setter which is the above is disclosed (for example, refer to Patent Document 2).
JP 2002-114537 A JP 2004-192205 A

  When the setter for heat treatment described in Patent Documents 1 and 2 is repeatedly used in the heat treatment temperature range of the glass substrate, warpage deformation occurs such that the mounting surface becomes convex, and the warpage deformation increases with use time. When this warpage deformation becomes large, the glass substrate is deformed following the warpage deformation of the setter. Furthermore, when heat treatment is performed with a roller hearth kiln, when the setter is transported with a roller, the contact area between the setter and the roller is reduced, so that not only the transport is not performed properly, but the setter gets caught on the roller, which is the worst case There was a risk that the roller or setter would break and the firing furnace had to be stopped.

  This invention is made | formed in view of the said situation, Comprising: It aims at providing the setter for glass substrate heat processing which is hard to generate | occur | produce a curvature deformation even if it uses repeatedly in the heat processing temperature range of a glass substrate.

The present inventors have found that the cause of warping deformation of the setter is due to the diffusion reaction of the alkali component in the glass substrate generated during the heat treatment to the setter. That is, the glass substrate for PDP usually contains Na ₂ O and K ₂ O, and the total amount thereof is about 7 to 18% by mass. Therefore, the glass substrate is directly placed on the setting surface of the setter and 450 to 650. When heat treatment is performed in a baking furnace set at 0 ° C., K and Na in the glass substrate diffuse to a setter in close contact with the glass substrate. Therefore, the crystal composition and the matrix glass phase composition on the setting surface of the setter change, and a volume difference occurs between the surface and the inside of the mounting surface, causing warpage deformation.

As a result of diligent research to solve the above problems, the present inventors have increased the contents of K ₂ O and Na ₂ O in the glass phase to such an extent that the heat resistance is not impaired. The present inventors have found that warp deformation hardly occurs even when used repeatedly in the temperature range, and propose as the present invention.

That is, the setter for glass substrate heat treatment is made of plate-like crystallized glass. In the setter for glass substrate heat treatment for placing a glass substrate on one surface for heat treatment, the crystallized glass has a K ₂ O value of 0.0. It is characterized by containing 8 to 4% by mass and 0.5 to 4% by mass of Na ₂ O.

Since the setter for heat treatment of a glass substrate according to the present invention is configured as described above, even if it is repeatedly used in the heat treatment temperature range of the glass substrate, warpage deformation is unlikely to occur. That is, if K ₂ O is less than 0.8% by mass or Na ₂ O is less than 0.5% by mass, the difference in concentration between K ₂ O and Na ₂ O between the setter and the glass substrate becomes large. K and Na in the substrate are likely to diffuse into the setter in close contact with the glass substrate, the composition of the crystal phase and glass phase near the setter surface changes, and the volume difference between the surface near the setter and inside increases. It is. On the other hand, when K ₂ O is more than 4% by mass or Na ₂ O is more than 4% by mass, the setter is likely to be deformed or warped due to low heat resistance. In addition, the thermal expansion coefficient increases and the thermal shock resistance decreases. A preferable range of K ₂ O is 1 to 3.5% by mass, and a preferable range of Na ₂ O is 0.8 to 3% by mass.

In the above configuration, when the heat-treating setter contains Li, specifically, the crystallized glass contains Li-β eucryptite, β-spodumene, β-quartz solid solution or β-spodumene solid solution as a crystal phase. _{In the case of 2} O—Al ₂ O ₃ —SiO ₂ based crystallized glass, if K ₂ O is less than 0.8% by mass and Na ₂ O is less than 0.5% by mass, Li and Due to the ion exchange reaction with K and Na in the glass substrate, the diffusion of K and Na from the glass substrate into the setter is increased, so that warping deformation is further increased. Therefore, if the amount of K ₂ O or Na ₂ O of the setter made of a material containing Li is increased, the ion exchange reaction can be prevented, and the effect of suppressing the warp deformation of the setter becomes large.

Further, it is preferable that the crystal phase does not contain crystals containing Na or K (for example, NaAlSiO ₄ , KAlSiO ₄ , KAlSi ₂ O ₆ , KNa ₃ (AlSiO ₄ ) _4, etc.). When Na or K in the glass substrate diffuses into the setter, Na or K mainly diffuses into the matrix glass phase of the crystallized glass. In this way, Na or K in the glass substrate is setter. Difficult to diffuse inside. That is, if crystals containing Na and K do not precipitate, Na and K in the matrix glass phase are not used as crystal components, and the amount of Na and K in the matrix glass phase can be maintained. This is because the Na or K concentration difference from the setter is difficult to be attached.

In the above-described configuration, it is preferable that the crystallized glass contains 1 to 6% by mass of Li ₂ O. The Li ₂ O content is preferably as small as possible in order to suppress the ion exchange reaction during the heat treatment of the glass substrate. Specifically, the Li ₂ O content is preferably 6% by mass or less, but is damaged by rapid heating / cooling. In order to prevent the occurrence of slag, a large amount of Li ₂ O—Al ₂ O ₃ —SiO ₂ -based low expansion crystal or negative expansion crystal is precipitated, and the thermal expansion coefficient of the setter is 25 × 10 ⁻⁷ × / K or less. Since it is necessary, the content of Li ₂ O is required to be 1% by mass or more.

Further, the glass substrate is a glass substrate for PDP, may become a K ₂ O 3 mass% or more and a Na ₂ O glass containing more than 1.5%, K ₂ O is less than 0.8 wt% If Na ₂ O is less than 0.5% by mass, the difference in the concentration of K ₂ O and Na ₂ O between the glass substrate and the setter will increase, so that the diffusion of K and Na from the glass substrate into the setter will increase. , Warpage deformation is further increased. Therefore, if the amount of Na ₂ O or K ₂ O in the setter is increased, the effect of suppressing the warp deformation of the setter becomes large. Incidentally, Na ₂ O and K ₂ O of the glass substrate for PDP, since the content thereof is too too large strain point is low, is limited both in the 18 wt% at most.

Further, in the case of a large setter in which the area of the placement surface on which the glass substrate is placed is 8500 cm ² or more, since warpage deformation is particularly large, as described above, 0.8 to 4 mass of K ₂ O. % containing preferably contains Na ₂ O 0.5 to 4% by weight. In addition, even when the thickness of the glass substrate is 2 mm or less, the warp deformation of the glass substrate is more likely to occur following the deformation of the setter during the heat treatment, so that the effect of the above configuration is further increased.

Further, the glass substrate for heat treatment setter of the present invention, by mass _{percentage, Li 2 O 1~6%, Al} 2 O 3 15~30%, SiO 2 50~70%, TiO 2 + ZrO 2 2.5~6% It is produced by heat-treating a crystalline glass plate produced by a melting method at 700 to 1100 ° C. for 2 to 10 hours so as to contain 0.5 to 4% of Na ₂ O and 0.8 to 4% of K ₂ O. .

Preferred crystallized glass (crystallinity glass) is a mass _{percentage, SiO 2 50~70%, Al 2} O 3 15~30%, Li 2 O 1~6%, 0~2% ZnO, BaO 0~3% TiO ₂ 1-5%, ZrO ₂ 0.5-4%, P ₂ O ₅ 0-6%, MgO 0-2%, Na ₂ O 0.5-4%, K ₂ O 0.8-4 When the heat treatment is performed, β-quartz solid solution (β-eucryptite solid solution) or β-spodumene solid solution is precipitated as the main crystal.

  Below, the setter for glass substrate heat processing of this invention is demonstrated in detail using an Example.

  Table 1 shows Examples 1 and 2 and Comparative Examples 1 and 2 of the present invention.

  The crystallized glasses of Examples 1 and 2 and Comparative Examples 1 and 2 were prepared in batches so as to have the compositions shown in Table 1, and melted at 1650 ° C. for 20 hours. It was obtained by firing under the firing conditions described in 1.

  Identification of the precipitated crystal phase in the crystallized glass was performed using an X-ray diffractometer (manufactured by Rigaku Corporation).

The warp deformation is performed at a substantially central portion of the mounting surface of a setter having a size of 1250 × 700 × 5 mm (mounting surface area: 8750 cm ² ) at a high strain point glass for PDP having a size of 1000 × 560 × 2.8 mm ( After placing PP-8 manufactured by Nippon Electric Glass Co., Ltd., Na ₂ O: 5 mass%, K ₂ O: 10 mass%) and heating at 600 ° C. for 2 weeks, the setting surface shape of the setter is 3 Measurement was performed using a dimensional shape measuring apparatus, and evaluation was made based on the difference in height between the highest part and the lowest part.

  As can be seen from Table 1, in Examples 1 and 2, no warp deformation occurred. On the other hand, in Comparative Examples 1 and 2, warpage deformation occurred.

  As described above, the setter for heat treatment of a glass substrate according to the present invention is suitable as a setter for heat treatment of a glass substrate used not only for PDP but also for flat panel displays such as liquid crystal displays and FEDs.

Claims (7)

In a setter for glass substrate heat treatment comprising a plate-like crystallized glass and placing a glass substrate on one surface for heat treatment, the crystallized glass contains K ₂ O in an amount of 0.8 to 4% by mass, Na ₂ O Is contained in an amount of 0.5 to 4% by mass. The crystallized glass is a Li ₂ O—Al ₂ O ₃ —SiO ₂ based crystallized glass containing β-eucryptite, β-spodumene, β-quartz solid solution or β-spodumene solid solution as a crystal phase. The setter for heat-treating a glass substrate according to claim 1.   The setter for heat-treating a glass substrate according to claim 2, wherein the crystal phase does not contain crystals containing K and Na. The crystallized glass contains 1 to 6% by mass of Li ₂ O, The setter for heat treatment of a glass substrate according to any one of claims 1 to 3. Glass substrate is a glass substrate for PDP, a glass substrate for heat treatment setter according to any one of claims 1 to 4, characterized in that it consists of glass containing K ₂ O 3 to 15 wt%. Glass substrate, a glass substrate for heat treatment setter according to claim 5, characterized in that it consists of glass containing Na ₂ O 1.5 to 15 wt%. The setter for heat treatment of a glass substrate according to any one of claims 1 to 6, wherein an area of a placement surface on which the glass substrate is placed is 8500 cm ² or more.