JP4873166B2 - Setter for glass substrate heat treatment - Google Patents

Description

  The present invention relates to a setter for heat treatment of a large glass substrate, and in particular, 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. It relates to a setter for heat treatment of a flat glass substrate.

  In recent years, with the diversification of display devices, large screen flat displays are becoming the mainstream of display devices instead 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 gas discharge by application of a gas containment voltage, and the display screen is thinner than the display screen. For example, a 42-inch PDP module having a 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. It is made of crystallized glass, the flatness, which is the ratio of the warp per unit length specified in JIS R 3202, is 0.3% or less, and the surface roughness of the mounting surface is Ra value. A setter in the range of 0.1 to 1 μm is disclosed (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). As a further heat treatment for the setter, it is the gloss of the surface is 5 degrees or more, petalite _{(Li 2 O · Al 2 O} 3 · 8SiO 2) ceramics, beta-spodumene _{(Li 2 O · Al 2 O} 3 · 4SiO ₂₎ ceramics or β- Yuktobanian descriptor setter made of tight _{(Li 2 O · Al 2 O} 3 · 2SiO 2) ceramics have been disclosed (e.g., see Patent Document 3.).
JP 2002-114537 A JP 2006-8487 A JP 2005-180743 A

  When the setter for heat treatment described in Patent Documents 1 to 3 described above 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.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a setter for glass substrate heat treatment that is unlikely to warp and deform even when used repeatedly in the heat treatment temperature range of the glass substrate.

The present inventor has found that the cause of warping deformation of the setter is an increase in volume due to a diffusion reaction of an alkali component in the glass substrate generated during the heat treatment to the setter. That is, since the glass substrate for PDP usually contains about 10 to 15% by mass of Na ₂ O or K ₂ O in total, the glass substrate is directly placed on the setter mounting surface and fired at 450 to 650 ° C. When heat treatment is performed in the furnace, Na ⁺ ions and K ⁺ ions in the glass substrate diffuse to the setter in close contact with the glass substrate. For this reason, it was found that the crystal composition and the matrix glass phase composition on the setting surface of the setter were changed, causing an increase in volume and causing warping deformation.

  As a result of diligent research to solve the above problems, the present inventors have made it difficult for warp deformation to occur by forming concave portions with a specific depth and ratio on the mounting surface of the setter for heat treatment of a glass substrate. Are proposed as the present invention.

That is, a glass substrate for heat treatment setter of the present invention, the crystallization glass manufactured der is, a glass substrate for heat treatment setters for thermal treatment by placing the mounting surface of the glass substrate, the depth in the mounting surface 3 μm or more and 20 μm or less of recesses are present on average at a rate of 1 or more per 500 μm. The recess formed on the mounting surface of the setter can absorb the volume change due to the movement of ions, and warpage deformation is less likely to occur. The depth and number of the recesses on the setter mounting surface can be measured using, for example, a stylus type surface roughness measuring instrument. Specifically, it can be calculated by measuring the number of recesses having a depth of 3 μm or more and 20 μm or less at a constant distance, and converting the number to the number per 500 μm. Here, the depth of the concave portion indicates a distance D from the average line of the measurement curve to the tip of the concave portion as shown in the schematic diagram of the measurement curve of the setter surface shape in FIG. In addition, the width | variety of the recessed part in the vicinity of the setter surface mentioned later refers to the width W of the recessed part on the average line of a measurement curve.

  2ndly, the setter for heat processing of the glass substrate of this invention is characterized by the average surface roughness of a mounting surface being 0.1 micrometer-2 micrometers. By having a specific average surface roughness, it is possible to prevent the glass substrate from slipping due to the air cushion action and place the glass substrate stably. The average surface roughness is calculated according to the arithmetic average roughness specified in JIS B 0601.

Third, the setter for heat treatment of a glass substrate according to the present invention is a Li ₂ O—Al ₂ O ₃ —SiO ₂ based crystallized glass in which the crystallized glass contains β-quartz solid solution or β-spodumene solid solution as a crystal phase. characterized in that there.

Fourth, the glass substrate for heat treatment setter of the present invention is characterized in that the crystallization glass contains 1-8 wt% of Li 2 _O.

Fifth, the setter for heat treatment of a glass substrate according to the present invention is characterized in that the glass substrate is a high strain point glass and is made of a glass containing 5 to 30% by mass of Na ₂ O and K ₂ O in a total amount. To do.

Sixth, the setter for heat treatment of a glass substrate of the present invention is characterized in that the area of the mounting surface is 8500 cm ² or more.

The setter for heat treatment of a glass substrate according to the present invention forms Na ⁺ ions and K ⁺ ions in the glass substrate by diffusing into the setter in close contact with the glass substrate by forming a recess having a specific depth and ratio on the mounting surface. It is possible to absorb the volume change caused by this. Further, by forming the recess on the setter surface, the contact area between the glass substrate and the setter is reduced, and diffusion of ions to the setter can be reduced. As a result, warpage deformation due to repeated use is unlikely to occur.

A glass substrate for heat treatment setter of the present invention, characterized in that Ri crystallized glass made der, the depth 3μm or more and 20μm or less of the recess in the mounting surface, present in a proportion more than one per 500μm average of And

As described above, when Na ⁺ ions or K ⁺ ions diffuse from the glass substrate to the setter, the glass phase or crystal phase in the setter is altered, resulting in a volume change. If there is a recess capable of absorbing the volume change due to this alteration, the setter will not easily warp and deform even if it is diffused and altered. Since the setter for heat treatment of a glass substrate of the present invention has a recess that absorbs a volume change on the surface, even if a volume change occurs due to diffusion of Na ⁺ ions or K ⁺ ions, the volume change is absorbed by the recess. For this reason, even if the glass substrate is repeatedly used in the heat treatment temperature region, warpage deformation is unlikely to occur.

  When the concave portions formed on the setter surface are present as evenly dispersed as possible, the volume change can be absorbed by the entire setter, and even when heated for a long time, it is difficult to warp and deform. Specifically, on the setting surface of the setter, it is necessary that the recesses having a depth of 3 μm or more exist on average at a rate of 1 or more per 500 μm, and on the average, exist at a rate of 2 or more per 500 μm. It is preferable that the average amount is 5 or more per 500 μm. Although an upper limit is not specifically limited, Since it becomes easy to transfer the setter shape to substrate glass, it is preferable that it is 20 or less per 500 micrometers on average.

It should be noted that the depth of the concave portion needs to be 3 μm or more, preferably 3.5 μm or more, from the viewpoint of sufficiently absorbing the volume change of the setter when heated for a long time and suppressing warpage deformation. The above is preferable. The upper limit is preferably 20 μm or less because the glass substrate softens during heat treatment and the shape of the recesses on the setter surface may be transferred as it is.

The shape of the concave portion is not particularly limited, and if the depth is 3 μm or more and 20 μm or less , it can contribute to the absorption of the volume change of the setter, so any shape such as a groove shape or a hole shape can be used. I do not care. In particular, the groove shape is preferable in that the effect of absorbing the volume change is large and it is easy to form on the setter surface.

  When a groove is formed as a recess on the setter surface, the length is not particularly limited, but the larger the width, the greater the effect of absorbing the volume increase due to K diffusion, which is preferable. For example, when a groove is formed on the setter surface by polishing with abrasive grains, the width decreases from the surface to the depth direction, but the groove width near the surface is preferably 10 μm or more, and 15 μm. More preferably, it is more preferably 20 μm or more. However, if the width of the groove is too large, the shape of the groove on the setter surface may be transferred as it is due to the softening of the glass substrate during the heat treatment.

  The method for forming the recesses on the setter surface is not particularly limited, and examples thereof include polishing using a polishing machine, specifically, a method of lapping with a polishing machine using a predetermined number of abrasive grains.

A setter made of crystallized glass has a long life because it is relatively excellent in strength and is not easily damaged, and has a feature such as a high thermal conductivity and a large soaking effect. Since it is denser, it is more susceptible to volume changes due to the diffusion of Na ⁺ ions and K ⁺ ions as described above. Therefore, when crystallized glass is used as the setter, the effect of the present invention obtained by forming a recess on the setter surface is significant.

  Regarding the surface roughness of the setter, the arithmetic average roughness defined in JIS B 0601 is preferably 0.1 to 2 μm, and more preferably 0.2 to 1.5 μm. If the surface roughness of the setter is less than 0.1 μm, there is almost no gap between the surface of the glass substrate and the setting surface of the setter when the glass substrate is placed, and an air cushion action is generated and the glass substrate is setter. It is likely to be difficult to slide stably on the predetermined position. On the other hand, when the surface roughness of the setter is 2 μm or more, the glass substrate is softened during the heat treatment, and the uneven shape of the setter surface may be transferred as it is.

In the above-described configuration, the crystallized glass includes Li ₂ O—Al ₂ O ₃ —SiO ₂ based crystallized glass containing β-quartz solid solution or β-spodumene solid solution as a crystal phase . When using the crystallization glass, by ion exchange reaction between Na ⁺ ions and K ⁺ ions of Li ⁺ ions and the glass in the substrate contained in the setter, from the glass substrate into the setter Na ⁺ ions and K ⁺ Since the diffusion of ions increases, warpage deformation is further increased. In this case, the effect of this invention obtained by forming a recessed part in the setter surface will become a big thing.

In the above configuration, it is preferable that the crystallization glass contains 1-8 wt% of Li ₂ O. The Li ₂ O content is preferably as small as possible in order to suppress the ion exchange reaction in the heat treatment process of the glass substrate. Specifically, the Li ₂ O content is preferably 8% 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 low expansion crystal or negative expansion crystal is precipitated, and the thermal expansion coefficient of the setter is approximately 25 × 10 ⁻⁷ / K or less. Since it is necessary, the content of Li ₂ O is preferably 1% by mass or more.

In addition, when the glass substrate to be heat-treated is a glass substrate for PDP and is made of glass containing Na ₂ O and K ₂ O in a total amount of 5% by mass or more, warp deformation occurs particularly with a volume change due to ion exchange. It becomes easy. Therefore, when it uses for the heat processing of this glass substrate, the effect which suppresses the curvature deformation of the setter for glass substrate heat processing in this invention becomes a big thing. Incidentally, Na ₂ O and K ₂ O of the glass substrate for PDP, since the strain point when the content thereof is too large, too low, being limited to 30 weight% at the maximum in total. 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 present invention is further enhanced.

In the case of a large setter in which the area of the setter mounting surface is 8500 cm ² or more, and further 12000 cm ² or more, since warpage deformation is particularly large, the effect of the present invention obtained by forming a recess on the setter surface can be obtained. large.

  Although the thickness of a setter is not specifically limited, It is preferable that it is 2-10 mm. If the setter thickness is less than 2 mm, warping due to heating tends to occur, and the strength tends to be insufficient. On the other hand, when the thickness of the setter exceeds 10 mm, handling tends to be difficult or the amount of power used in the heat treatment furnace due to an increase in the heat capacity of the setter tends to increase.

  Although the setter for glass substrate heat processing of this invention is demonstrated in detail below based on an Example, this invention is not limited to this Example.

As crystallized glass for setter, transparent crystallized glass (manufactured by Nippon Electric Glass Co., Ltd., Neoceram N-0 (Li ₂ O content: 4% by mass)) is used, and as the ceramic sintered body, petalite crystal Li ₂ O—Al ₂ O ₃ —SiO ₂ ceramic sintered body (Li ₂ O content: 6% by mass) containing 70% by mass. After the surfaces of the crystallized glass and ceramic sintered body were ground by a diamond generator, in Example 1 and Reference Example 1 , a polishing machine was used using # 600 polishing abrasive grains mixed with 1 wt% # 400 polishing abrasive grains. In Example 2 and Reference Example 2 , lapping is performed with a polishing machine using # 600 abrasive grains mixed with 10% by weight of # 400 abrasive grains. In Comparative Examples 1 and 2, # 1000 abrasive grains are used. The surface was processed by lapping each using a polishing machine to form groove-like recesses.

  The depth and number of the recesses formed on the surface of the setter were measured by using a Surfcom 756A manufactured by Tokyo Seimitsu Co., Ltd. at a driving speed of 0.3 mm / s, 1500 μm, and the detected recesses having a depth of 3 μm or more were measured. It calculated | required converted into the number per 500 micrometers. In addition, the measurement was performed at a central part of the setter surface and at a total of five places in the central part and four places near the midpoints of the four corners, and the average value was calculated.

The warp deformation of the setter is a high strain point for PDP having a size of 1000 × 560 × 2.8 mm at the substantially central portion of the setting surface of the setter having a size of 1250 × 700 × 5 mm (mounting surface area: 8750 cm ² ). Glass (manufactured by Nippon Electric Glass Co., Ltd., PP-8; containing Na ₂ O: 5 mass%, K ₂ O: 10 mass%) was heated at 600 ° C. for 2 weeks, and then the setting surface shape of the setter Was measured using a three-dimensional shape measuring apparatus, and evaluated by the difference in height between the highest part and the lowest part. The results are shown in Table 1.

  About slip of the glass substrate due to the air cushion action, the same high-strain-point glass for PDP of 1000 × 560 × 2.8 mm as above from 10 cm above the center of the mounting surface of the same 1250 × 700 × 5 mm setter as above. The movement of the glass substrate due to the air cushion action was examined. When the glass substrate did not protrude from the setter due to the air cushion action, it was indicated as ◯, and when even a part of the corner of the glass substrate protruded from the setter, it was indicated as x. The results are shown in Table 1.

As can be seen from Table 1, the glass substrate heat treatment setters of Examples 1 and 2 and Reference Examples 1 and 2 did not warp, and in Comparative Examples 1 and 2, warp deformation occurred. Further, in Examples 1 and 2 and Reference Examples 1 and 2 , the problem of slipping of the glass substrate due to the air cushion action did not occur, but in Comparative Examples 1 and 2, the glass substrate slipped and moved due to the air cushion action. , Protruded from the setter.

  As described above, the setter for heat treatment of a glass substrate of the present invention is suitable as a setter for heat treatment of a glass substrate used for flat panel displays such as liquid crystal displays and FEDs as well as PDPs.

It is a schematic diagram of the measurement curve in the setter surface measured using the stylus type surface roughness measuring device.

Explanation of symbols

D Depth of recess W Width of recess near the setter surface

Claims (7)

Crystallization glass manufactured der is, a glass substrate for heat treatment setters for thermal treatment by placing the mounting surface of the glass substrate, the depth 3μm or more and 20μm or less of the recess in the mounting surface, and the average A setter for heat-treating a glass substrate, wherein the setter is present at a rate of 1 or more per 500 μm.   The setter for heat treatment of a glass substrate according to claim 1, wherein an average surface roughness of the mounting surface is 0.1 to 2 μm. _{3. The} crystallized glass is Li ₂ O—Al ₂ O ₃ —SiO ₂ based crystallized glass containing β-quartz solid solution or β-spodumene solid solution as a crystal phase. Setter for heat treatment of glass substrate. Crystallization glass is a glass substrate for heat treatment setter according to any one of claims 1 to 3, characterized in that it contains 1-8 wt% of Li 2 _O. Glass substrate, a high strain point glass, a glass substrate according to any one of claims 1 to 4, characterized in that it consists of glass containing 5 to 30 mass% of Na 2 _O and K _{2 O} in total Setter for heat treatment. The glass substrate heat treatment setter according to any one of claims 1 to 5, wherein the glass substrate is a glass substrate for a plasma display panel. The setter for heat treatment of a glass substrate according to any one of claims 1 to 6 , wherein an area of the mounting surface is 8500 cm ² or more.