JP2013075808A - Method for producing glass substrate and glass substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a glass substrate, which can increase end face strength, can reduce variation of the end face strength and can effectively inhibit generation of particles in the end face; and to provide the glass substrate.SOLUTION: A method for producing a glass substrate includes an end face treatment step of grinding the end face of the glass substrate, and etching the ground end face; where the roughness of the end face of the glass substrate after etching treatment in the end face treatment step is 10-35 μm in an Rsm value.

Description

  The present invention relates to a glass substrate manufacturing method and a glass substrate.

  Conventionally, in the manufacturing process of glass substrates used for image display devices such as liquid crystal displays and plasma displays, the molded glass substrate is cut into a predetermined size, and then is chipped or cracked due to impact during transportation. The cut end face is chamfered to prevent it. Fine irregularities are formed on the end surface of the chamfered glass substrate, and extraneous glass pieces, so-called glass particles, and foreign matters such as abrasive particles adhere to them. In order to remove these foreign substances, in Patent Document 1 (Japanese Patent Laid-Open No. 2002-160147), a process of mirror-finishing the end surface of the glass substrate is performed. In Patent Document 2 (Japanese Patent Laid-Open No. 2007-51017), A process of etching the end surface of the glass substrate to remove foreign matters attached to the unevenness of the end surface is performed. Moreover, in patent document 3 (Unexamined-Japanese-Patent No. 2005-162519), the process which smoothes the acute convex part currently formed in the end surface of a glass substrate by the process etc. which etch the end surface of a glass substrate with an acidic solution is performed. It has been broken.

  However, in order to remove the minute unevenness formed on the end surface of the glass substrate, there is a problem that it takes time and cost to completely mirror the end surface of the glass substrate. Further, the conventional etching method has a problem that the end face strength after the etching process is low and the end face strength varies greatly. There is also a problem that the generation of particles with the passage of time after the etching process cannot be sufficiently suppressed.

  An object of the present invention is to provide a glass substrate manufacturing method and a glass substrate that can improve end face strength, reduce variation in end face strength, and effectively suppress generation of particles on the end face. is there.

  The manufacturing method of the glass substrate which concerns on this invention includes the end surface process process of grinding the end surface of a glass substrate and etching-processing the ground end surface. In the end face processing step, the roughness of the end face of the glass substrate after the etching process is 10 μm or more and 35 μm or less in terms of Rsm value.

  The glass substrate manufacturing method according to the present invention includes an end surface processing step of processing an end surface that is a cut surface of a glass substrate manufactured by an overflow downdraw method or the like and cut to a predetermined size. Specifically, the end surface is subjected to polishing processing such as R chamfering, and then isotropic etching is performed on the end surface. The end face before the etching treatment has a concavo-convex shape in which cracks of various sizes are formed. On the other hand, the end face after the etching process has a concavo-convex shape with a relatively large Rsm value, that is, with an increased periodicity, because a small-sized crack changes to a large-sized crack by the etching process. That is, on the end face after the etching process, the recess formed on the surface has a wide and shallow shape. This effectively suppresses the generation of glass particles on the end face after the etching treatment, as compared with the end face having many small size cracks. Further, even when foreign matter such as glass particles adheres to the end face after the etching treatment, the foreign face can be easily removed by cleaning the end face. Furthermore, since the end face after the etching process has a large irregularity periodicity and the curvature radius of the tip of the recess is also large, the strength of the end face of the glass substrate is sufficiently ensured, and variations in the end face strength are sufficiently reduced. .

  In the manufacturing method of the glass substrate which concerns on this invention, it is preferable to make an etching chemical | medical solution penetrate | penetrate inside the crack of an end surface, and to etch an end surface in an end surface processing process. In the present invention, an etching chemical that can penetrate deeply into a small crack on the end face is used so that the crack formed on the end face by the etching process is enlarged and, as a result, a wide and shallow recess is formed on the end face. It is preferable.

  In the manufacturing method of the glass substrate which concerns on this invention, it is preferable to etch-process an end surface so that the curvature radius of the front-end | tip of the concave crack of an end surface may be enlarged in an end surface processing process.

In the method for producing a glass substrate according to the present invention, in the end face processing step, the viscosity of the etching chemical is preferably 4 × 10 ⁻¹ Pa · s or less. In the present invention, the viscosity of the etchant is appropriately adjusted with a thickener or the like in order to penetrate the etchant deeply into the cracks at the end face of the glass substrate.

  The glass substrate according to the present invention includes an end face that is etched after the grinding process. The roughness of the end surface of the glass substrate is 10 μm or more and 35 μm or less in terms of Rsm value.

  The glass substrate according to the present invention is preferably a glass substrate for a display device having a length of 1000 mm or more on each side and a thickness of less than 1.5 mm.

  The method for producing a glass substrate and the glass substrate according to the present invention can improve end face strength, reduce variation in end face strength, and effectively suppress generation of particles on the end face.

It is a whole block diagram of the glass plate manufacturing apparatus which concerns on this embodiment. It is a graph showing the relationship between the end surface roughness and intensity | strength of the glass substrate which concerns on a present Example. It is a graph showing the relationship between the end surface roughness of the glass substrate which concerns on a present Example, and the number of particles adhering to an end surface.

<Embodiment>
(1) Whole structure of glass plate manufacturing apparatus First, the whole structure of the glass plate manufacturing apparatus 100 in which the manufacturing method of the glass substrate which concerns on this invention is performed is demonstrated, referring FIG. The glass plate manufacturing apparatus 100 mainly includes a dissolution tank 200, a clarification tank 300, a molding apparatus 400, and a cleaning tank 500. In the melting tank 200, the glass raw material is melted to produce molten glass. The molten glass generated in the melting tank 200 is sent to the clarification tank 300. In the clarification tank 300, bubbles contained in the molten glass are removed. The molten glass from which bubbles have been removed in the clarification tank 300 is sent to the molding apparatus 400. In the forming apparatus 400, a glass plate is continuously formed from molten glass by an overflow down draw method and cut into a predetermined size. The glass plate formed and cut by the forming apparatus 400 is sent to the cutting / processing apparatus 450. In the cutting / processing apparatus 450, the glass plate is cut into a glass substrate of a predetermined size, and after the end face processing of the glass substrate is performed as will be described later, the glass plate is sent to the cleaning tank 500. In the cleaning tank 500, the surface of the glass substrate is cleaned. The glass substrate cleaned in the cleaning tank 500 is shipped as a product. The glass substrate is used as a glass substrate for flat panel displays such as liquid crystal displays and plasma displays.

  In the present embodiment, the cut end surface of the glass substrate that has been formed by the forming apparatus 400 and cut to a predetermined size is processed in the cutting / processing apparatus 450 before being sent to the cleaning tank 500. Next, the glass substrate end face process, which is a process characteristic of the glass substrate manufacturing method according to the present invention, will be described in detail.

(2) End surface treatment of glass substrate The glass plate formed and cut by the forming device 400 is sent to the cutting / processing device 450, where the four sides of the glass plate are cut and processed into a glass substrate of a predetermined size. . That is, the glass substrate has four end surfaces formed by cutting a glass plate. The thickness of the glass substrate is less than 1.5 mm.

  2. Description of the Related Art Conventionally, chamfering is performed by grinding an end surface of a glass substrate into an R surface or a C surface in order to prevent chipping or cracking due to impact or the like during conveyance of the glass substrate. By this chamfering process, foreign substances such as glass particles and abrasive particles are generated from the end face. Specifically, since the minute unevenness derived from the grinding process of the glass substrate is formed on the end surface of the glass substrate, by applying vibration or the like to the end surface, stress is applied to the minute unevenness, It drops off from the end face as glass particles and particle generation occurs. As described above, when glass particles are spawned from the end surface, which is a grinding / polishing surface of the glass substrate, with time, the glass particles adhere to the surface of the glass substrate and the like. As a result, simplification of the cleaning of the glass substrate in a subsequent process is hindered, or scratches are formed on the glass substrate.

  The inventor has studied the end face etching of the glass substrate to be carried out after the chamfering step, and by performing etching by a method described later, while suppressing the generation of glass particles over time, the large glass substrate It was found that the generation of dust can be reduced without unevenness in the side direction.

  Specifically, in the end surface processing step of the glass substrate of the present invention, after chamfering the glass substrate, the end surfaces formed on the four sides of the glass substrate are etched with an etching chemical solution, and the roughness of the end surface is determined as an Rsm value. To 10 μm to 35 μm.

In this embodiment, the etchant used for etching the end face of the glass substrate is an aqueous solution containing one or more substances selected from the group consisting of hydrofluoric acid, hydrochloric acid, sulfuric acid, nitric acid and phosphoric acid. Is used. In particular, the etching chemical solution preferably contains hydrofluoric acid as a main component. In this embodiment, the etching chemical solution has a viscosity of 4 × 10 ⁻¹ Pa · s or less at the temperature at which the etching process is performed. In order to achieve this viscosity range, the viscosity of the etching chemical is adjusted by adding a thickener. As the thickener, one or more substances selected from the group consisting of magnesium compounds, surfactants, flocculants, water-absorbing polymers, antifoaming agents, urea, natural sugars, adhesives and the like are used. . In addition, when the solubility of the thickener in water is low, an etching solvent may be prepared by further adding an organic solvent such as ethanol.

  In the present embodiment, the glass substrate that has been subjected to the R chamfering process and the etching process on the end surface is then cleaned in the cleaning tank 500 and finally shipped as a product.

(3) Features In this embodiment, the end surface of the glass substrate is etched, and the roughness of the end surface is set to 10 μm or more and 35 μm or less in terms of Rsm, so that the size of the crack formed on the end surface of the glass substrate is uniform. Isotropic etching is performed. Usually, the end surface of the glass substrate before an etching process has a crack of various sizes. In the present embodiment, by performing isotropic etching on the end face of the glass substrate, the size of the crack on the end face is increased regardless of the size of the crack. Thereby, with the progress of the etching process, adjacent cracks are integrated with each other, and the periodicity of the irregularities on the end surface of the glass substrate becomes large, and the concave portions on the end surface become wide and shallow. As a result, even when foreign matter such as glass particles adheres to the end surface of the etched glass substrate, since the size of the crack on the end surface is relatively large, the foreign matter can be easily removed by cleaning the end surface.

  Further, in this embodiment, compared to the end face before the etching process having a large number of small size cracks, the generation of glass particles due to the chipping or cracking of the small size crack is effective on the end face after the etching process. It is suppressed. That is, the amount of foreign matter generated from the end surface of the glass substrate with time can be suppressed by the etching process. Thereby, generation | occurrence | production of the particle which generate | occur | produces from the end surface of a glass substrate and adheres to the surface of a glass substrate can be suppressed. That is, since the cleanliness of the surface of the glass substrate is improved, it is possible to simplify a cleaning process required in a subsequent process such as a reception process in a panel manufacturer or a device manufacturer.

  Moreover, in this embodiment, the end surface of the glass substrate is etched, and an etching chemical solution is infiltrated into the crack, thereby increasing the size of the crack and making the concave portion of the end surface of the glass substrate wide and shallow. . Specifically, the roughness of the end surface of the glass substrate is adjusted within the range of 10 μm or more and 35 μm or less in terms of Rsm value, thereby increasing the periodicity of the unevenness of the end surface. Thereby, the strength of the end surface of the glass substrate can be sufficiently secured, and the variation in the end surface strength can be sufficiently reduced.

Moreover, in this embodiment, in order to etch the end surface of a glass substrate, the etching chemical | medical solution whose viscosity is 4 * 10 < ^-1 > Pa * s or less is used. The lower the viscosity of the etchant, the easier it is for the etchant to penetrate deeper into the cracks at the end face of the glass substrate, so isotropic etching can be performed efficiently even with small cracks. As a result, the end surface of the glass substrate can be formed into a desired shape.

<Example>
Hereinafter, based on the present embodiment, the relationship between the Rsm value representing the roughness of the end surface of the glass substrate, the strength of the glass substrate, and the number of particles attached to the end surface of the glass substrate over time was measured. Examples will be described with reference to the following Table 1.

本実施例では、ガラス基板の端面をＲ面取り加工した後に、エッチング薬液を染み込ませたロールをガラス基板の端面に押し当てて端面にエッチング処理を施したガラス基板を９枚作成した。なお、エッチング処理に用いたエッチング薬液はフッ酸系の薬液であり、その使用温度範囲は４５℃〜５５℃であった。また、エッチング薬液は、その使用温度範囲における粘度が１×１０^-2Ｐａ・ｓ〜１×１０^-1Ｐａ・ｓとなるように、増粘剤で粘度があらかじめ調整された。以下、これらの９枚のガラス基板を、試料１〜９という。試料１〜９は、表１に示されるように、互いに異なる端面粗さ（Ｒｓｍ値）を有するように、端面のエッチング処理が行われた。図２は、試料１〜９の「端面のＲｓｍ値（μｍ）」を横軸に採り、試料１〜９の端面の「平均強度（Ｎ／ｍｍ²）」および「０．０１％強度（Ｎ／ｍｍ²）」を縦軸に採ったグラフである。「平均強度」は、ガラス基板の端面に荷重を負荷して破損した時点における荷重（破壊応力）についての複数回の測定結果の平均値である。「０．０１％強度」は、測定対象であるガラス基板の０．０１％が破損する破壊応力である。一般的に、「０．０１％強度」が「平均強度」に比べて小さいほど、ガラス基板の端面強度のバラツキが大きい。図３は、試料１〜９の「端面のＲｓｍ値（μｍ）」を横軸に採り、試料１〜９の「端面のパーティクル数」を縦軸に採ったグラフである。「端面のパーティクル数」は、エッチング処理後に、それぞれ２日、１週間または１ヶ月保管した時点における試料１〜９の端面に付着していたパーティクル（微粒子状の異物）の数である。なお、端面粗さの測定には、凹凸の詳細な形状を測定するために、レーザ顕微鏡（オリンパス製ＯＬＳ３１００）を使用した。

In this example, after the end surface of the glass substrate was chamfered, nine glass substrates were prepared by pressing a roll soaked with an etching chemical solution against the end surface of the glass substrate and etching the end surfaces. In addition, the etching chemical | medical solution used for the etching process was a hydrofluoric acid type chemical | medical solution, and the use temperature range was 45 to 55 degreeC. Moreover, the viscosity of the etching chemical solution was adjusted in advance with a thickener so that the viscosity in the operating temperature range was 1 × 10 ⁻² Pa · s to ¹ × 10 ⁻¹ Pa · s. Hereinafter, these nine glass substrates are referred to as Samples 1 to 9. As shown in Table 1, the samples 1 to 9 were subjected to the etching process on the end faces so as to have different end face roughnesses (Rsm values). FIG. 2 shows “Rsm value (μm) of end face” of samples 1 to 9 on the horizontal axis, and “average strength (N / mm ² )” and “0.01% strength (N / Mm ² ) ”on the vertical axis. The “average strength” is an average value of a plurality of measurement results for a load (fracture stress) at the time when the end surface of the glass substrate is damaged by applying a load. “0.01% strength” is a breaking stress at which 0.01% of a glass substrate to be measured is broken. Generally, the smaller the “0.01% strength” is than the “average strength”, the greater the variation in the end face strength of the glass substrate. FIG. 3 is a graph in which “Rsm value (μm) of end face” of samples 1 to 9 is taken on the horizontal axis and “number of particles on end face” of samples 1 to 9 is taken on the vertical axis. The “number of particles on the end face” is the number of particles (particulate foreign matter) adhering to the end faces of the samples 1 to 9 when stored for 2 days, 1 week, or 1 month after the etching process, respectively. For measuring the end face roughness, a laser microscope (OLYMPUS OLS3100) was used to measure the detailed shape of the irregularities.

  Table 1 also includes measurement data regarding Comparative Example 1 and Comparative Example 2. Comparative Example 1 relates to a glass substrate whose end face is R-chamfered and is not etched thereafter. Comparative Example 2 relates to a glass substrate that has been subjected to polishing using a polishing wheel after R-chamfering the end face, and thereafter not subjected to etching treatment.

  From Table 1, FIG. 2 and FIG. 3, the following can be understood. FIG. 2 shows that the end face strength of the glass substrate tends to increase as the Rsm value of the end face of the glass substrate increases. That is, the Rsm value of the end surface of the glass substrate is preferably as high as possible from the viewpoint of strength. On the other hand, FIG. 3 shows the result of suppressing the generation of glass particles from the end surface of the glass substrate with the passage of time as the Rsm value of the end surface of the glass substrate is larger.

  In this example, it was confirmed that the Rsm value of the end surface of the glass substrate was 10 μm or more, and the effect of reducing the variation in end surface strength was confirmed as compared with Comparative Example 1 and Comparative Example 2. In Samples 1 to 9 in Table 1, the number of glass particles detected on the end surface of the glass substrate was kept low regardless of the Rsm value of the end surface of the glass substrate when two days passed after the etching process. With the passage of time after the etching treatment, the number of glass particles detected on the end face of the glass substrate tended to increase gradually. However, the detected values were all within the allowable range, and were sufficiently removed by the subsequent cleaning process.

  Moreover, in the samples 5 to 9 etched so that the Rsm value of the end face of the glass substrate is 15 μm or more, the number of glass particles detected on the end face of the glass substrate is 1 month after the etching process. While being suppressed to less than 10, extremely good results were obtained such as improvement in end face strength and reduction in variation in end face strength.

  Note that the Rsm value of the end surface of the glass substrate is preferably 11 μm or more when compared with the measurement data of Comparative Example 1, and the Rsm value of the end surface of the glass substrate is 12 μm or more when compared with the measurement data of Comparative Example 2. It turned out to be more preferable.

<Modification>
(1) Modification A
In this embodiment, an acidic etchant is used to etch the end face of the glass substrate, but an alkaline etchant may be used.

(2) Modification B
In this embodiment, an etching chemical solution having a viscosity of 4 × 10 ⁻¹ Pa · s or less is used to etch the end surface of the glass substrate, but a plurality of types of etching chemical solutions having different viscosities may be used. In this case, the end face may be etched using an etchant having a high viscosity after the end face is etched using an etchant having a low viscosity. First, by using an etching chemical solution having a low viscosity, an etching process is mainly performed to increase small-sized cracks formed on the end face. Next, an etching process is performed to make the size of the cracks on the end face uniform by using an etching chemical having a high viscosity.

(3) Modification C
In the present embodiment, the grinding process for chamfering the end surface of the glass substrate is performed before the etching process of the end surface of the glass substrate. However, the R chamfering process is performed before the etching process, and then the polishing process is performed using a grinding wheel. You may go. Since the depth of cracks on the end face can be suppressed within a predetermined value by polishing with the polishing wheel, the end face can be etched more effectively in the subsequent steps, and the end face strength can be improved. Can do.

(4) Modification D
In the present embodiment, the R chamfered shape is formed on the end surface by grinding the end surface of the glass substrate. However, the same etching process may be performed by forming the C chamfered shape by grinding.

(5) Modification E
In the present embodiment, end face processing was performed using a glass substrate of G5.5 size (1300 mm × 1500 mm). In the etching process of the end surface using a chemical solution, processing variation in the side direction becomes a problem. By using the Rsm value as a parameter, etching unevenness in the side direction of the glass substrate can be achieved only by measuring the roughness of the end surface. It is possible to grasp whether or not Therefore, according to the present embodiment, even if the glass substrate is G5 size (1100 mm × 1300 mm) or larger, the etching process can be fed back without performing a destructive inspection.

(6) Modification F
In this embodiment, the etching process was performed using a glass substrate having a thickness of 0.5 mm, but the same effect can be obtained even if the thickness of the end surface is a thin substrate having a thickness of 0.3 mm to 0.4 mm. Play. In particular, by applying the present invention to a thin substrate, it is possible to reduce variations in end face strength and improve end face strength, and to effectively reduce cracks resulting from end face cracks.

  The method for producing a glass substrate and the glass substrate according to the present invention can improve end face strength, reduce variation in end face strength, and effectively suppress generation of particles on the end face.

DESCRIPTION OF SYMBOLS 100 Glass plate manufacturing apparatus 200 Dissolution tank 300 Clarification tank 400 Molding apparatus 450 Cutting / processing apparatus 500 Cleaning tank

JP 2002-160147 A JP 2007-51017 A JP 2005-162519 A

Claims (6)

In the manufacturing method of a glass substrate including an end face processing step of grinding an end face of the glass substrate and etching the ground end face,
In the end face processing step, the roughness of the end face after the etching process is 10 μm or more and 35 μm or less in terms of Rsm value.
A method for producing a glass substrate. In the end face processing step, an etchant is infiltrated into the cracks on the end face, and the end face is etched.
The manufacturing method of the glass substrate of Claim 1. In the end face processing step, the end face is etched so as to increase the radius of curvature of the tip of the concave crack on the end face.
The manufacturing method of the glass substrate of Claim 2. In the end surface treatment step, the viscosity of the etching chemical is 4 × 10 ⁻¹ Pa · s or less.
The manufacturing method of the glass substrate of Claim 2 or 3. It has an end face that has been etched after grinding,
The roughness of the end face is 10 μm or more and 35 μm or less in terms of Rsm value.
Glass substrate. It is a glass substrate for a display device having a length of 1000 mm or more on each side and a thickness of less than 1.5 mm.
The glass substrate according to claim 5.

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