JP7311842B2 - GLASS SUBSTRATE FOR DISPLAY AND METHOD FOR MANUFACTURING GLASS SUBSTRATE FOR DISPLAY - Google Patents

Description

TECHNICAL FIELD The present invention relates to a glass plate, a method for manufacturing a glass plate, and an end face inspection method.

As is well known, flat panel displays (FPDs) such as liquid crystal displays, plasma displays, and organic EL displays are being promoted to have higher definition. Along with this, a dense electric circuit is formed in the glass plate used as the substrate for the FPD in the manufacturing process of the FPD.

The end face of the glass plate for FPD is usually subjected to end face processing such as grinding or polishing with a grindstone, but cracks occur on the surface of the end face after processing (surface processed by the grindstone). exist. This crack may be evaluated by surface roughness such as arithmetic mean roughness Ra. In addition, cracks existing on the end face after processing grow due to various treatments in the FPD manufacturing process, and can cause generation of glass powder (particles) from the end face. The glass powder generated from the end faces tends to hinder the formation of the electric circuit (for example, disconnection of the electric circuit, etc.) and cause manufacturing defects of the FPD. Therefore, it is required to inspect the properties of the end surface of the glass plate after processing the end surface to grasp the amount of glass powder that may be generated from the end surface in the subsequent process.

Here, Patent Literature 1 discloses a method for grasping the amount of glass powder that can be generated from the end surface of the glass plate. In this method, the end face of the glass plate is slid while being pressed against the end face of the resin tube. As a result, the glass powder present on the end surface of the glass plate is scraped off while applying friction to the end surface of the glass plate. Then, the scraped glass powder is sucked from the tip of the resin tube, and the number thereof is counted by a counter.

JP 2010-230646 A

However, even with the method disclosed in Patent Document 1, the amount of glass powder that may be generated cannot be accurately grasped, and it is difficult to accurately inspect the properties of the end face. The present invention, which has been made in view of such circumstances, is to establish a technique that can accurately inspect the properties of the end face of a glass plate after end face processing, and to remove glass powder that may be generated from the end face in a post-process as much as possible. A technical problem is to provide a glass plate in which the

As a result of extensive research, the inventors of the present invention have found that the glass powder generated from the end surface in the post-process is not caused only by cracks evaluated by surface roughness such as arithmetic mean roughness Ra, It was found that microcracks not evaluated by surface roughness such as arithmetic mean roughness Ra and latent cracks existing inside the surface are also generated. In order to accurately evaluate the properties of the end face in consideration of the effects of microcracks and latent cracks, that is, the amount of glass powder generated from the end face in a subsequent process (for example, the manufacturing process of FPD), microcracks and latent cracks It was found that it is effective to grow the surface of the end face and to evaluate the number of concave portions formed on the surface of the end face. Here, the term "recess" includes not only cracks present on the surface of the end face but also depressions formed on the surface of the end face due to peeling of glass powder (the same shall apply hereinafter).

Based on the above findings, the method for inspecting the end face of a glass plate according to the present invention, which was invented to solve the above problems, is a method for inspecting the properties of the end face of a glass plate having an end face formed by a grindstone. A treatment step of chemically treating the end face to promote formation of recesses on the end face, an imaging step of taking an image of the end face after the chemical treatment, and an image is used to determine the area of the recess with respect to the area of the end face. is characterized by comprising a calculation step of calculating the ratio occupied by

In this inspection method, chemical treatment (for example, chemical cleaning) is performed in the treatment process, and the end face (end face after end face processing) made of a ground or polished surface is evaluated by surface roughness such as arithmetic mean roughness Ra. It grows microcracks that are not exposed and latent cracks that exist inside the surface of the end face. As a result, a concave portion is formed on the end face, and a state that can be evaluated with a scanning electron microscope or the like is obtained. In addition, recesses are also formed on the surface of the end surface by partly peeling off the glass and generating glass powder. Then, by performing the imaging step and the calculation step, the ratio of the area of the recesses to the area of the end face is calculated, and the amount of recesses formed on the surface of the end face and the quality of the properties based on this can be evaluated. As described above, according to this inspection method, it is possible to accurately inspect the properties of the end face of the glass plate after the end face processing.

In the above method, in the calculation step, before calculating the ratio, it is preferable to discriminate between the concave portion and the portion other than the concave portion by performing a binarization process on the image.

This makes it easier to more accurately calculate the ratio of the area occupied by the concave portion on the image in the calculation process, which is more advantageous in accurately and efficiently inspecting the properties of the end face.

In the above method, it is preferable to use a treatment liquid at 40° C. to 80° C. in the treatment step.

In this way, microcracks and latent cracks can be efficiently grown in the treatment process, and the formation of recesses on the end faces can be efficiently promoted.

Further, a method for manufacturing a glass plate according to the present invention, which has been invented to solve the above problems, includes a manufacturing step of manufacturing a plurality of glass plates having an end surface formed by a grindstone-processed surface under the same conditions; A sampling step of extracting an inspection glass plate from a glass plate, an inspection step of performing the above end face inspection method on the inspection glass plate, and the properties of the end faces of the plurality of glass plates based on the results of the inspection step. It is characterized by comprising a determination step of determining

In this manufacturing method, a plurality of glass plates having end surfaces formed by grinding surfaces are manufactured under the same conditions by executing the manufacturing process. Then, the inspection glass plate is extracted from the plurality of glass plates by executing the extraction step. Here, both the glass plate for inspection and the plurality of glass plates excluding this glass plate for inspection are manufactured under the same conditions, so both are regarded as substantially the same glass plate. can be done. Therefore, as a result of the inspection process performed on the inspection glass plate, if the properties of the end face of the inspection glass plate are good, each of the plurality of glass plates excluding the inspection glass plate is subjected to the determination process. It is possible to obtain a glass plate having good end face properties, that is, a glass plate in which glass powder that may be generated from the end face in a post-process is suppressed as much as possible.

In the manufacturing method described above, in the manufacturing process, it is preferable to manufacture a plurality of glass plates using a grindstone having a dynamic balance of 8 g·mm or less.

In this way, it is possible to efficiently obtain a glass plate having good end face properties.

In the above manufacturing method, in the manufacturing process, F [N] is the magnitude of the force that presses the grindstone against the end surface of the glass plate, R [m/min] is the peripheral speed of the grindstone during rotation, and R [m/min] is the end surface of the glass plate. When the speed at which the grindstone is moved relative to the surface is set to V [m/min], it is preferable to carry out the polishing step with the value of W represented by the following formula [Equation 1] set to 30 or less.

In this way, it is possible to obtain a glass plate with even better end face properties.

Further, a glass plate according to the present invention, which has been devised to solve the above problems, is a glass plate having a polished end face, and is a glass plate containing 5% by mass of KOH and 5% by mass of NaOH. After chemically treating the end face with an alkaline solution for 2 hours to promote the formation of recesses on the end face, when observed with a scanning electron microscope at a magnification of 1000 times, the area of the end face It is characterized in that the ratio of the area occupied by the concave portion is 30% or less.

According to such a glass plate, it is possible to suppress as much as possible glass powder that may be generated from the end surface in a post-process.

In the above glass plate, the above ratio is preferably 7% or less.

According to such a glass plate, it is possible to further suppress glass powder that may be generated from the end surface in a post-process.

Further, a method for manufacturing a glass plate according to the present invention, which has been devised to solve the above-described problems, is a method comprising the step of polishing the end face of the glass plate with a whetstone, wherein the end face of the glass plate is F [N] is the force that presses the grindstone, R [m/min] is the peripheral speed of the rotating grindstone, and V [m/min] is the speed at which the grindstone moves relative to the end face of the glass plate. Then, the value of W represented by the above [Equation 1] is set to 30 or less, and the step of polishing is performed.

According to this production method, it is possible to obtain a glass plate in which glass powder that may be generated from the end surface in a post-process is suppressed as much as possible, specifically a glass plate in which the above ratio is 7% or less.

ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to test|inspect the property of the end face correctly about the glass plate after end face processing. In addition, it is possible to provide a glass plate in which glass powder that can be generated from the end surface in a post-process is suppressed as much as possible.

It is a top view which shows the preparation process in the manufacturing method of the glass plate which concerns on 1st embodiment of this invention. It is a top view which shows the extraction process in the manufacturing method of the glass plate which concerns on 1st embodiment of this invention. FIG. 4 is a plan view showing an inspection step (a cutting step in the method for inspecting an end face of a glass plate) in the method for manufacturing a glass plate according to the first embodiment of the present invention; FIG. 2 is a three-dimensional view conceptually showing an inspection step (processing step in the method for inspecting an end face of a glass plate) in the method for manufacturing a glass plate according to the first embodiment of the present invention. FIG. 2 is a three-dimensional view conceptually showing an inspection step (processing step in the method for inspecting an end face of a glass plate) in the method for manufacturing a glass plate according to the first embodiment of the present invention. FIG. 2 is a three-dimensional view conceptually showing an inspection step (processing step in the method for inspecting an end face of a glass plate) in the method for manufacturing a glass plate according to the first embodiment of the present invention. It is a vertical side view which shows the inspection process (process process in the end surface inspection method of a glass plate) in the manufacturing method of the glass plate which concerns on 1st embodiment of this invention. It is a figure which shows the image used for the inspection process (calculation process in the end face inspection method of a glass plate) in the manufacturing method of the glass plate which concerns on 1st embodiment of this invention. It is a top view which shows the manufacturing method of the glass plate which concerns on 2nd embodiment of this invention. FIG. 2 is a diagram showing the relationship between the value of W represented by the formula [Formula 1] (formula [Formula 2]) and the ratio (crack rate) of the area of the concave portion to the area of the end surface of the glass plate in the example. is.

<First embodiment>
DESCRIPTION OF THE PREFERRED EMBODIMENTS A glass plate, a method for manufacturing a glass plate, and an end surface inspection method according to a first embodiment of the present invention will be described below with reference to the accompanying drawings.

The method for manufacturing a glass plate according to the present embodiment includes a manufacturing step ( FIG. 1 ) of manufacturing a plurality of glass plates G having end faces Ga made of polished surfaces under the same conditions (FIG. 1); A sampling process (FIG. 2) for extracting the glass plate GX, an inspection process (FIGS. 3 to 6) for inspecting the properties of the end surface Ga of the inspection glass plate GX, and a plurality of sheets based on the results of the inspection process. and a determination step of determining the properties of the end surface Ga of the glass plate G.

As shown in FIG. 1, in the production process, in the production of each glass plate G, the grinding wheel 1 for grinding the end face Ga of the glass plate G and the end face Ga of the glass plate G after grinding are polished. Polishing whetstone 2 is used. In the present embodiment, one grinding wheel 1 and one polishing wheel 2 are used for processing one end face Ga, but at least one of the two grinding wheels 1 and 2 may be used in plurality. Note that the end face Ga of the glass plate G before grinding and polishing is a cut end face formed in a cutting process that has already been performed before the manufacturing process.

The grinding wheel 1 and the polishing wheel 2 process an end face Ga parallel to the X direction while moving synchronously in the T direction with respect to a glass plate G fixed on a surface plate (not shown). Grooves (not shown) for processing the end face Ga are formed in a plurality of upper and lower stages on the outer peripheral portions (rotating peripheral portions) of both grindstones 1 and 2 . The end surface Ga is machined by pressing one of the grooves of the plurality of stages against the end surface Ga. Further, the rotating direction of both grindstones 1 and 2 may be clockwise or counterclockwise when viewed from the Z direction (in a plan view). Here, the dynamic balance of both grindstones 1 and 2 is 8 g·mm or less (the same is true when using a plurality of at least one of both grindstones 1 and 2). As a result, microcracks and latent cracks introduced into the end surface Ga can be reduced, and the ratio of the area of the concave portion to the area of the end surface described later can be reduced to 30% or less. In addition, the moving speed of both grindstones 1 and 2 in the T direction may be set arbitrarily.

The grinding wheel 1 is a grindstone for shaping the cross-sectional shape of the end face Ga (cross-sectional shape perpendicular to the X direction), and processes the end face Ga while the position in the Y direction is fixed. At that time, the end face is ground and the ridgeline of the end face is chamfered to form a round or planar chamfered surface. The end surface Ga after processing by the grinding wheel 1 becomes a ground surface. On the other hand, the polishing whetstone 2 is a whetstone for finishing the end surface Ga after grinding, and includes a chamfered surface while being pressed against the end surface Ga with a constant pressing force. The end face Ga is processed. The end face Ga after processing by the polishing grindstone 2 becomes a polished surface. The grinding wheel 1 may process the end surface Ga while being pressed against the end surface Ga with a constant pressing force.

The grinding wheel 1 is preferably a metal-bonded grindstone that employs a metal bond as a bonding material for abrasive grains. The metal used as the binder is preferably a mixture of two or more selected from iron, copper, cobalt, nickel, tungsten, etc., and particularly preferably contains iron. The abrasive grains bonded to the grinding wheel 1 are preferably diamond abrasive grains, and the grain size is preferably #300-600.

The polishing whetstone 2 is preferably a resin-bonded whetstone that employs a resin bonding material (resin bond) as a bonding material for abrasive grains. A thermosetting resin is preferably used as the resin binder. As specific examples, phenol resins, epoxy resins, polyimide resins, polyurethane resins, and the like can be used as resin binders. As the abrasive grains bonded to the grinding wheel 2, diamond grains, aluminum oxide grains, silicon carbide grains, cubic boron nitride grains, metal oxide grains, metal carbide grains, metal nitride grains and the like can be used. The grain size of the abrasive grains is preferably #100 to #3000, more preferably #200 to #1000.

At this point, the glass plate G whose end surface Ga parallel to the X direction has been ground and polished is turned 90° in plan view so that the end surface Ga parallel to the Y direction is ground and polished. Let Then, the end face Ga, which was parallel to the Y direction before the direction change, is ground and polished in the same manner. Thus, in the present embodiment, all of the end faces Ga corresponding to the four sides of the rectangular glass plate G are polished surfaces.

Using both the grinding wheels 1 and 2, a plurality of glass plates G successively carried onto the surface plate are ground and polished, respectively, to obtain a glass having an end surface Ga formed by a polished surface. A plurality of plates G are obtained. This completes the manufacturing process. The plurality of glass plates G are processed under the same conditions (e.g., the same forming conditions, the same cutting conditions, and the same grinding/polishing conditions) throughout the entire process until the grinding and polishing processes are completed, or processing is done. That is, the plurality of glass plates G are substantially the same glass plate.

When the manufacturing process is completed, the sampling process is performed. As shown in FIG. 2, in the sampling step, a glass plate G randomly extracted from a plurality of glass plates G is used as an inspection glass plate GX. The number of glass plates G extracted as the inspection glass plate GX may be one or more. In this embodiment, the case of extracting only one sheet will be exemplified.

When the sampling process is completed, the inspection process is executed. The inspection process is performed by the glass plate end surface inspection method according to the present embodiment. This inspection process includes an extraction process, a processing process, an imaging process, and a calculation process, which will be described later.

In the inspection step (glass plate end face inspection method), first, as shown in FIG. 3, a cutting step is performed to cut out a portion of the outer peripheral edge of the inspection glass plate GX to form a glass sample GS. The glass sample GS includes the end surface Ga (polished surface) of the inspection glass plate GX. The size of the glass sample GS may be any size, but in this embodiment, it is 15 mm×10 mm in plan view.

When the cutting process is completed, next, as conceptually shown in FIGS. 4a to 4c, the end surface Ga of the glass sample GS (the surface that was the end surface Ga of the inspection glass plate GX before the cutting process) is cut. A treatment step is performed to promote the formation of the recesses GC on the end surface Ga by chemical treatment. In this embodiment, an alkaline cleaning liquid L is used as a processing liquid for chemical treatment. Specifically, by immersing the end face Ga of the glass sample GS shown in FIG. 4a in the alkaline cleaning liquid L shown in FIG. , forming a recess GC that can be evaluated with a scanning electron microscope or the like (see FIG. 4c). In addition, recesses GC that can be evaluated with a scanning electron microscope or the like are also formed when latent cracks existing inside the end face Ga grow, become coarser, and are exposed on the surface. In addition, a recess is formed on the surface of the end surface Ga as part of the glass is peeled off to generate glass powder. This also forms a concave portion GC that can be evaluated with a scanning electron microscope or the like.

As the alkaline cleaning liquid L, a commercially available alkaline cleaning agent for glass substrates can be used. An acid cleaning liquid may be used as the treatment liquid, and a commercially available acid cleaning agent for glass substrates can be used as the acid cleaning liquid. In these cases, the undiluted solution may be used as the alkaline cleaning solution L without diluting the glass substrate cleaning agent. Alternatively, the cleaning agent for glass substrates may be diluted with water and used. The processing liquid is not limited to the cleaning liquid, and a solution having the same ability as the cleaning liquid to promote the formation of the concave portions GC may be used. The temperature of these treatment liquids (washing liquids) is preferably 20°C to 90°C, more preferably 40°C to 80°C. The time (treatment time) for immersing the end face Ga of the glass sample GS in the treatment liquid is preferably 15 minutes to 3 hours, more preferably 1 hour to 2 hours.

When an alkaline processing liquid such as the alkaline cleaning liquid L is used, one or more of KOH, (CH ₃ ) ₄ NOH, NaOH and the like can be used as the alkaline component. The total content of alkaline components can be 0.05% to 20% by mass, preferably 3% to 15% by mass. When an acidic treatment liquid such as an acid cleaning liquid is used, one or more of HF, HCl, HNO ₃ , H ₂ SO ₄ and the like can be used as the acid component, and HF is essential. is preferred. In the present embodiment, KOH and NaOH are used as the alkaline components of the alkaline cleaning liquid L, and their concentrations are both 5% by mass. Further, the temperature of the alkaline cleaning liquid L is 50° C., and the end surface Ga of the glass sample GS is immersed in the alkaline cleaning liquid L for 2 hours.

Here, FIG. 4b is a diagram conceptually showing a manner in which the end surface Ga of the glass sample GS is immersed in the alkaline cleaning solution L. Specifically, under the condition shown in FIG. soaked in L.

As shown in FIG. 5, the glass sample GS is immersed in an alkaline cleaning liquid L contained in a container 4 (for example, a beaker) while being suspended and supported by a support member 3. At this time, the end surface Ga is positioned so as not to come into contact with the inner side surface or the bottom surface of the container 4 . The container 4 is placed in a hot bath 5 in which water W is stored as an ultrasonic transmission medium, and the end surface Ga is ultrasonically cleaned by ultrasonic vibrations propagated through the water W to the alkaline cleaning liquid L. The temperature of the water W in the hot bath 5 can be controlled so as to adjust the temperature of the alkaline cleaning liquid L. Note that the ultrasonic cleaning may not be performed, and the end surface Ga may be subjected to chemical cleaning only.

When ultrasonic cleaning is performed, the time for performing ultrasonic cleaning within the above cleaning time is preferably 1 minute to 60 minutes, more preferably 3 minutes to 30 minutes. The temperature of the water W during ultrasonic cleaning is preferably 15°C to 80°C, more preferably 25°C to 60°C. Furthermore, the frequency of ultrasonic cleaning is preferably 10 kHz to 1000 kHz, more preferably 20 kHz to 200 kHz.

After the above cleaning time has passed, the glass sample GS is pulled out of the alkaline cleaning solution L, washed to remove the alkaline cleaning solution L adhering to the end surface Ga thereof, and then dried until the water content disappears. This completes the process.

After the treatment process is completed, an image 6 as shown in FIG. 6 is obtained by performing an imaging process of imaging an image 6 of the end face Ga after cleaning. In this imaging step, the end surface Ga of the glass sample GS is magnified and imaged using a microscope. The term "microscope" as used herein includes an optical microscope, a scanning electron microscope, a laser microscope, an X-ray CT, a CCD camera, and the like. Magnification for imaging is preferably 100 times to 10000 times, more preferably 500 times to 2000 times.

In this embodiment, a scanning electron microscope, Quanta250FEG manufactured by FEI, is used to capture an image 6 of the end face Ga after cleaning under conditions of 1000 times magnification and 173 dpi resolution. More specifically, the backscattered electron image of the end face Ga was taken. Also, the brightness was set to 90 and the contrast was set to 80.

After the imaging process is completed, the image 6 is then used to perform a calculation process of calculating the ratio of the area of the recesses GC to the area of the end face Ga. In this calculation step, the image 6 is subjected to a binarization process before the ratio is calculated, thereby distinguishing between the concave portion GC and the portion other than the concave portion GC.

In this embodiment, the image 6 shown in FIG. Accordingly, the portion of the image 6 corresponding to the concave portion GC becomes black, and the portion corresponding to the portion other than the concave portion GC becomes white. Then, the ratio of the number of black pixels after the binarization processing to the number of pixels of the image 6 was calculated, and the ratio was defined as the ratio of the area of the concave portion GC to the area of the end surface Ga. The ratio calculated under the above conditions was 24.3%. Scion Image manufactured by Scion was used as image analysis software. Thereby, the calculation process is completed, and the inspection process (the end surface inspection method of the glass plate) is completed.

When the inspection process is completed, finally, the determination process is performed. In this embodiment, if the area ratio calculated in the inspection step (calculation step) is 30% or less, the plurality of glass plates G are judged to be acceptable, and if the area ratio exceeds 30%, the plurality of glass plates The glass plate G of was determined to be unacceptable. Here, the inspection glass plate GX, which is the base of the glass sample GS, and the plurality of glass plates G other than the inspection glass plate GX are substantially the same glass plate. Therefore, it is possible to determine pass/fail for a plurality of glass plates G based on the ratio of the area calculated using the inspection glass plate GX. Then, when it is judged as acceptable, each of the plurality of glass plates G is shipped as a glass plate in which glass powder that can be generated from the end surface Ga is suppressed as much as possible. On the other hand, if it is determined to be unsatisfactory, an adjustment process may be performed to adjust the grinding and polishing conditions in the manufacturing process. In this embodiment, in the adjustment process, it is confirmed whether the dynamic balance of the grinding wheel 1 and the polishing wheel 2 is 8 g mm or less. should be done. As a result, the ratio of the area of the subsequent glass plates G can be made 30% or less.

According to the method for manufacturing a glass plate according to this embodiment, it is possible to obtain a glass plate in which the ratio of the area of the concave portion to the area of the end face is 30% or less. According to such a glass plate, it is possible to suppress as much as possible glass powder that may be generated from the end surface in a post-process. From the viewpoint of further suppressing the generation of glass powder, the ratio is preferably 25% or less, more preferably 20% or less. From the viewpoint of suppressing an increase in manufacturing cost, the above ratio is preferably 1% or more, more preferably 5% or more, and most preferably 10% or more.

In the glass plate of the present invention, the ratio of the area of the concave portion to the area of the edge surface is determined by chemically treating the edge surface for 2 hours using an alkaline solution containing 5% by mass of KOH and 5% by mass of NaOH at 50 ° C. After promoting the formation of recesses on the end face by using a scanning electron microscope, the measurement shall be made by observing at a magnification of 1000 times. Ultrasonic cleaning shall not be performed in the above chemical treatment. Further, in the above observation, a Quanta250FEG manufactured by FEI was used as a scanning electron microscope, and the end surface was imaged as a backscattered electron image. shall identify the part of Assume that the resolution is set to 173 dpi, the brightness is set to 90, and the contrast is set to 80 for image pickup. For the binarization processing, Scion Image manufactured by Scion Co. is used as image analysis software, and brightness is set to 100 as a threshold value.

The shape of the end face can be, for example, a shape having a planar end face and a round or planar chamfered surface. In this case, it is assumed that a scanning electron microscope is used to take an image of a planar end surface. Moreover, the shape of the end face may be a shape consisting only of a curved surface (for example, a semi-cylindrical surface) without a flat surface. In this case, the tip (top) of the curved surface is imaged with a scanning electron microscope.

<Second embodiment>
Hereinafter, a method for manufacturing a glass plate according to a second embodiment of the present invention will be described with reference to the accompanying drawings.

As shown in FIG. 7, the method for manufacturing a glass plate according to the second embodiment is similar to the manufacturing process in the method for manufacturing a glass plate according to the first embodiment. Therefore, in the description of the second embodiment, elements that are substantially the same as the elements already described in the first embodiment are given the same reference numerals to omit duplicate descriptions, and the first embodiment ( Only differences from the manufacturing process) will be described.

The method for manufacturing a glass plate according to the second embodiment manufactures a glass plate G in which the ratio of the area of the concave portions GC to the area of the end surface Ga (hereinafter referred to as crack rate) is 7% or less. It is a method for The second embodiment differs from the manufacturing process of the first embodiment described above in that two grindstones are used for processing the end surface Ga of the glass plate G. FIG. That is, in the second embodiment, in addition to the grinding wheel 1 and the polishing wheel 2, a polishing wheel 7 for polishing the end surface Ga between the two grinding wheels 1 and 2 is used. As a result, the end surface Ga of the glass plate G is successively subjected to grinding by the grinding wheel 1, polishing by the polishing wheel 7 (rough polishing), and polishing by the polishing wheel 2 (finish polishing).

The grinding wheel 1 is preferably a metal-bonded grindstone that employs a metal bond as a bonding material for abrasive grains. The metal employed as the binder is preferably copper, iron, cobalt, or the like. The abrasive grains bonded to the grinding wheel 1 are preferably diamond abrasive grains, and the grain size is preferably #350-500. The surface roughness Ra of the end surface Ga after grinding by the grinding wheel 1 is, for example, 0.5 μm to 0.8 μm.

The polishing whetstone 7 used for rough polishing is preferably a resin-bonded whetstone that employs a resin bonding material (resin bond) as a bonding material for abrasive grains. The resin used as the binder is preferably polyurethane resin, polyimide resin, phenol resin, or the like. The abrasive grains bonded to the polishing grindstone 7 are preferably diamond grains, and the grain size is preferably #400 to #600. The surface roughness Ra of the end surface Ga after polishing by the polishing grindstone 7 is, for example, 0.1 μm to 0.3 μm.

The polishing whetstone 2 used for final polishing is preferably a resin bond whetstone that employs a resin bonding material (resin bond) as a bonding material for abrasive grains. The resin used as the binder is preferably polyurethane resin, polyimide resin, phenol resin, or the like. The abrasive grains bonded to the grinding wheel 2 are preferably diamond grains or silicon carbide grains. When diamond particles are used, the particle size is preferably #1000 to #1500, and when silicon carbide particles are used, the particle size is preferably #400 to #800. The surface roughness Ra of the end surface Ga after polishing by the polishing grindstone 2 is, for example, 0.06 μm to 0.09 μm.

In the present embodiment, when polishing the end face Ga with the polishing wheel 2, the magnitude of the force (magnitude of the force along the Y direction) pressing the polishing wheel 2 against the end face Ga is F [N], When the peripheral speed of the polishing grindstone 2 during rotation is R [m/min], and the speed at which the polishing grindstone 2 is moved relative to the end surface Ga (speed along the X direction) is V [m/min], the following is adjusted to 30 or less. By doing so, it is possible to manufacture a glass plate G having a crack rate of 7% or less. From the viewpoint of reliably removing microcracks on the end surface Ga and latent cracks existing inside the end surface Ga, it is preferable that the value of W is 1 or more.

The above value of F is preferably adjusted within the range of 10N to 70N. Moreover, it is preferable to adjust the value of R in the range of 500 m/min to 5000 m/min. Furthermore, the value of V is preferably adjusted within the range of 0.5 m/min to 50 m/min.

In order to verify the effect of the present invention, regarding the glass plate G manufactured in the same manner as in the second embodiment, the value of W represented by the above [Formula 2] formula ([Formula 1] formula), The relationship with the above crack rate was investigated.

The glass plate G was manufactured under a total of 26 conditions while changing the values of F, R and V above. Specifically, the glass plate G was manufactured under each of 17 conditions under which the value of W was 30 or less and 9 conditions under which the value of W was over 30. Then, the value of the crack rate was calculated for the glass plate G manufactured under each condition in the same manner as the inspection process of the first embodiment.

FIG. 8 shows the relationship between the value of W and the crack rate clarified from this verification. As shown in the figure, the glass sheets G manufactured under 17 conditions in which the value of W is 30 or less have a crack rate of 7% or less. On the other hand, most of the glass sheets G manufactured under the nine conditions in which the value of W exceeds 30 had a crack rate of more than 7%.

From the above, if the glass plate G is manufactured in the same manner as in the second embodiment, the glass plate G having a crack rate of 7% or less (glass powder that can be generated from the end surface Ga in a later process can be used as much as possible. It can be seen that it is possible to suitably produce a glass sheet G) which is effectively suppressed.

Here, the method for manufacturing a glass plate and the method for inspecting an end face according to the present invention are not limited to the configurations and modes described in the above embodiments. In the above-described first embodiment, the properties of the end face formed by the polished surface are inspected, but the properties of the end face formed by the ground surface may be inspected.

Also, images may be captured at a plurality of locations on the end surface. For example, in the case of having a planar end surface and a round or planar chamfered surface, images are taken of the planar end surface and both chamfered surfaces sandwiching the end surface, and the area of the recess is determined for each image. You may calculate the ratio which occupies. When images are taken at a plurality of locations on the end face, an average value may be calculated from the ratios at the plurality of locations and used in the determination step. Alternatively, the determination step may use the maximum value among the above ratios at a plurality of locations.

Also, in the second embodiment described above, two whetstones for polishing are used, but the present invention is not limited to this. Only one whetstone may be used for polishing, or three or more may be used. In either case, the surface roughness Ra of the end face of the glass plate is reduced to 0.1 μm immediately before the end face of the glass plate is processed by the polishing grindstone whose W value is adjusted to 30 or less. It is preferable to keep the thickness within the range of up to 0.3 μm.

G Glass plate Ga End surface GC Recess GX Glass plate for inspection L Alkaline cleaning solution R Peripheral speed of grindstone V Speed of relative movement of grindstone to the end surface of the glass plate 2 Polishing grindstone 6 Image

Claims (3)

A display glass substrate having an end face made of a polished surface,
Using an alkaline solution containing 5% by mass of KOH and 5% by mass of NaOH at 50° C., the end face was chemically treated for 2 hours to promote the formation of a plurality of recesses on the end face. A glass substrate for a display, wherein the ratio of the area of the plurality of concave portions to the area of the end face is 1% or more and 30% or less when observed with a microscope at a magnification of 1000 times. 2. The glass substrate for display according to claim 1 , wherein the ratio is 1% or more and 7% or less. 3. The method for producing a glass substrate for display according to claim 1 or 2, comprising the step of polishing the end face of the glass plate with a grindstone,
F [N] is the force of pressing the grindstone against the end surface of the glass plate, R [m/min] is the peripheral speed of the grindstone during rotation, and the grindstone is pressed against the end surface of the glass plate. A display glass characterized in that the polishing step is performed with the value of W represented by the following formula [Equation 1 ] set to 30 or less, where V [m/min] is the speed of relative movement. Substrate manufacturing method.

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