JP5440786B2 - Glass substrate and manufacturing method thereof - Google Patents

Description

  In the present invention, a polishing surface protruding outward from the outer peripheral edge of each of the front surface and the back surface to the central portion in the plate thickness direction is formed on the end surface existing between the outer peripheral edges of the front surface and the back surface, and then further polished in place. The present invention relates to a glass substrate to which is applied and a manufacturing method thereof.

  As is well known, glass substrates for flat panel displays (FPDs) such as liquid crystal displays (LCDs) and plasma displays (PDPs) are being promoted to become larger as the screen size of FPDs increases. This is the current situation. This type of glass substrate for FPD, etc. is molded by a glass maker using a downdraw method, a float method, etc., then cut to a predetermined size and shipped, but the outer periphery of the front and back surfaces of the glass substrate The end face after cutting existing between the ends is a fracture surface. For this reason, defects and breakage are likely to occur in the subsequent process, and chamfering by polishing is usually performed on the end face for the purpose of preventing this.

  It is advantageous that the chamfering process on the end surface of the glass substrate after the cutting is performed by a polishing process over a plurality of times (for example, twice). As an example, according to Patent Document 1 (paragraphs [0005], [0009], etc.), first, using an auxiliary polishing grindstone whose outer peripheral surface parallel to the rotation axis is a polished surface having a high roughness, the glass is used. Preliminary rough polishing (primary polishing) of the end face of the substrate is performed, and then the rough polishing processing unit is used by using a polishing grindstone whose outer peripheral surface parallel to the rotation axis is a concave polishing surface having a low roughness. It is disclosed that final polishing (secondary polishing) is performed.

  In the polishing method described in paragraph [0005] of the same document, both the primary polishing and the secondary polishing form a polishing surface having an arcuate cross-sectional shape that protrudes outward on the end surface of the glass substrate. In contrast, the polishing method described in paragraph [0009] of the same document is a method of polishing with a circular arc cross section that is convex outward on the end surface of the glass substrate by primary polishing. After performing a rough polishing process so that a surface is formed, both side corners of the end surface (each boundary between the end surface, the front surface, and the back surface) are finish-polished by secondary polishing. Also, in paragraph [0009] of the same document, as a secondary polishing, a pair of upper and lower rotary grinding wheels for finishing polishing are brought into pressure contact with an end face of the glass substrate after the primary polishing process at an angle of 45 °. Is described.

  On the other hand, according to Patent Document 2, a polished surface having an arcuate cross section is formed on the end surface between the outer peripheral ends of the front and back surfaces of the heat strengthened glass plate that has been subjected to the heat strengthening treatment. Polishing to form a planar polishing surface with an inclination of about 45 ° at each boundary between the end surface, the front surface and the back surface after the polishing processing (primary polishing) It is disclosed that a treatment (secondary polishing) is performed. Further, in the same document, the surface maximum unevenness of the end surface of the above-mentioned circular arc shape is finished to be 0.05 mm or less, and the surface unevenness of the boundary between the end surface and the surface and the back surface is 0.007 mm or less. It is also disclosed that it can be finished.

JP 2002-59346 A Japanese Patent Laid-Open No. 9-278466

  By the way, among the polishing methods disclosed in the above-mentioned Patent Documents 1 and 2, first, after performing a primary polishing process to form a polished surface having an arcuate cross-sectional shape that protrudes outward on the end surface of the glass substrate. According to the method of performing the secondary polishing treatment to form a planar polishing surface at each boundary between the end surface and the front and back surfaces, there are problems as shown below.

  That is, when a polishing surface having an arcuate cross section that is convex outward is formed on the end surface of the glass substrate by performing a primary polishing process, the boundary between the front and back surfaces and the end surface after polishing is in the longitudinal direction. It does not have a form extending linearly. Specifically, as shown in a plan view in FIG. 7, a boundary portion z1 between the end surface 3b1 having an arcuate cross section after the primary polishing and the front surface (or back surface) 2a1 has an uneven shape, and the boundary portion z1 Is originally present at the position indicated by the straight line zx, but is actually biased toward the center of the front surface (or back surface) 2a1.

  Such a phenomenon is caused by the fact that the abrasive grains of the grindstone bite into the front surface (or back surface) 2a1 side rather than the straight line zx that should be the original boundary when the end surface 3b1 of the glass substrate 11 is polished. This is caused by peeling off the front surface (or back surface) 2a1 side portion. Such a situation becomes more prominent due to the necessity of relatively moving the grindstone at a high speed with respect to the longitudinal direction of the end face of the glass substrate in order to improve productivity.

  However, according to Patent Documents 1 and 2, as shown in a longitudinal section in FIG. 8, in the vicinity of the straight line zx that should essentially be the boundary between the front surface (or back surface) 2a of the glass substrate 11 and the end surface 3b1, When the grinding surface 6b1 of the grindstone contacts with an inclination of about 45 °, the grinding surface 6b1 of the grindstone is not in contact with the actual boundary portion z1. Therefore, the grindstone cannot polish the uneven boundary portion z1 or can only polish a part of the boundary portion z1, and as a result, the uneven boundary portion z is completely polished. Therefore, a situation occurs in which a chamfered portion made of a specific polished surface cannot be formed at the boundary portion. In such a situation, in order to improve productivity, it is necessary to relatively move the grindstone at a high speed with respect to the longitudinal direction in the vicinity of the straight line zx that should essentially be a boundary. If you can't do it, it will be even more pronounced.

  And, as a result of intensive efforts, the inventors have lost or damaged the glass substrate after polishing with respect to the end face because of the occurrence of chipping, cracking, etc. starting from the boundary z1 or It was found that the cracks and the like originate from the progress. Therefore, with the polishing methods disclosed in Patent Documents 1 and 2, it is extremely difficult to avoid the glass substrate from being damaged or damaged in the post-processing step after end face polishing.

  In addition, after polishing the end surface of the glass substrate, if the actual boundary between the end surface and the front surface or the back surface is uneven, glass chipping or glass particles are peeled and removed from that portion, and the effective surface of the glass substrate ( It adheres to the surface having a region to be a surface on which a film such as a pattern is formed in the display manufacturing process, and causes a problem that it cannot be removed even after a cleaning process. In addition, glass particles and the like that are generated during the polishing of the end face and adhere to the surface of the glass substrate tend to stay at the uneven boundary between the end face and the surface in the cleaning process. For these reasons, in the drying process, glass particles and the like are attached to the surface of the glass substrate, leading to a fatal defect that the quality of the glass substrate is degraded.

  On the other hand, in Patent Document 2, as described above, the surface maximum unevenness of the end surface is finished to be 0.05 mm or less, and the surface unevenness of the boundary portion between the end surface and the surface and the back surface is 0.007 mm or less. It is described that it will be finished. However, even if productivity is ignored and the chamfered portion is formed by increasing the amount of polishing at the boundary portion, as shown in FIG. 9, the end surface is rough as shown by the roughness curve Y (solid line). If it is a surface state and the boundary portion (chamfered portion) is a rough surface state as shown by the roughness curve Z (broken line), it becomes meaningless as will be described later.

  In this case, according to the polishing method disclosed in the same document, the roughness curve Z indicating the rough surface state of the boundary portion has a lower height difference than the roughness curve Y indicating the rough surface state of the end surface. Although predictable, the roughness of the grindstone surface, the number of trajectory trains and the trajectory direction of the abrasive grains, and other factors affect the period in a complicated manner. Therefore, in such a polishing method, the period of the roughness curve Z indicating the rough surface state of the boundary is unknown, and is equal to the period of the roughness curve Y indicating the rough surface state of the end face as illustrated, or It may be shorter.

  Therefore, the glass substrate still has the problem that in accordance with the knowledge of the present inventors, chipping, cracking, etc. occur starting from this boundary, and the glass substrate may be damaged or broken. Further, there remains a problem that glass particles and the like may still stay in the boundary portion and reduce the quality of the glass substrate.

  In view of the above circumstances, the present invention improves productivity and reliably forms an appropriate chamfered portion at the boundary between the polished end surface and the front surface and / or the back surface of the glass substrate. Appropriate relationship between the surface properties of the end surface and the surface properties of the front and / or back side boundary portions of the end surface, effectively preventing defects and breakage of the glass substrate, and glass particles, etc. The technical problem is to improve the quality of the glass substrate while avoiding the problems.

An apparatus according to the present invention, created to solve the above technical problem, has a front surface, a back surface, and an end surface existing between outer peripheral ends of the front surface and the back surface, and performs a polishing process on the end surface. With respect to the glass substrate on which the polished surface protruding outward from the outer peripheral edge of each of the front surface and the back surface to the central portion in the plate thickness direction is formed, each of the end surface after the polishing treatment and each of the front surface and the back surface at least one of the boundary portion, wherein with the chamfered portion comprising a specific polishing surface by applying different specific grinding process and the polishing process is formed, ten-point average roughness Rz ₂ of the particular polished surface of the chamfer, The specific length RSm ₂ of the roughness curve element of the specific polished surface of the chamfered portion is smaller than the ten-point average roughness Rz ₁ of the polished surface of the end face not subjected to the specific polishing treatment, Polishing process Characterized in that greater than the average length RSm ₁ of the roughness curve element of the polished surface of the end face that is not a. Here, as the “polishing surface projecting outward from the outer peripheral edge of each of the front surface and the back surface to the center portion in the plate thickness direction”, a polishing surface (end surface) having a substantially arc-shaped cross section or a part of the end surface A case where a chamfered portion is formed can be mentioned. Note that the surface roughness was measured by using a Tokyo Seimitsu Co. Surfcom 590A, JIS B0601: at 2001, the ten-point average roughness _{Rzjis (Rz 1, Rz 2)} , and average length of roughness curve element RSm (RSm ₁ , RSm ₂ ) is calculated (hereinafter the same).

  According to such a configuration, by first polishing only the end surface of the glass substrate, each boundary portion between the end surface, the front surface, and the back surface has an uneven shape in a plan view, and the center side and the back surface of the front surface. Even if it is formed to be deviated toward the center side, at least one of these boundary portions, that is, the required boundary portion, is a completely chamfered portion made of a specific polishing surface by performing a specific polishing process. It is formed with. Therefore, even though the actual boundary portion is uneven in plan view and is biased toward the center side of the front and back surfaces as in the prior art, the position of the boundary portion that should originally exist has an inclination of about 45 °. Since the grindstone is in contact, the problem that a chamfered part made of a specific polishing surface cannot be formed at the actual boundary part, particularly the problem when the productivity is increased, is effectively avoided. In detail, chipping or cracking occurs from the boundary, and the glass substrate is chipped or damaged, glass pieces or glass particles are peeled and removed from the boundary, and glass particles stay in the boundary during the cleaning process. And problems such as glass particles and the like adhering to the surface of the glass substrate in the drying step and degrading the quality are avoided. Moreover, not only is the 10-point average roughness of the chamfered portion formed of the specific polished surface formed at the boundary portion smaller than the 10-point average roughness of the end surface not subjected to the specific polishing treatment, but also the roughness of the chamfered portion. Since the average length of the curved element is larger than the average length of the roughness curve element of the end face, the glass substrate is damaged starting from the boundary as described above, or the boundary is the cause. Thus, problems such as glass particles degrading the quality of the glass substrate can be avoided.

In this case, the ten-point average roughnesses Rz ₂ and Rz ₁ of the specific polished surface satisfy Rz ₂ ≦ 1.5 μm and satisfy the relationship of 1.5 ≦ Rz ₁ / Rz ₂ ≦ 10.0. preferable.

In this way, it is possible to efficiently eliminate the presence of minute chips, cracks, etc. that existed before polishing on the specific polished surface of the chamfered portion formed at the above-described boundary portion. Breakage of the glass substrate starting from the portion is more reliably suppressed, the breaking strength around the end face is increased, and problems such as generation and retention of glass particles at the boundary are further effectively avoided. . In particular, by making Rz ₂ ≦ 1.5 μm and making the chamfered portion substantially a mirror surface, a chamfered portion comprising a specific polished surface at a boundary portion where a large uneven portion remaining after polishing of the end surface is removed and stress concentration easily occurs Is flattened. And since the end surface is rougher than the chamfered portion, the surface properties of the part from the end surface to the front surface and / or back surface through the chamfered portion are, in order from the end surface side, rough surface, polished mirror surface, molding surface, etc. Since it becomes a perfect mirror surface and the roughness and smoothness gradually change, stress concentration is effectively suppressed, and the fracture strength around the end face is remarkably improved. When Rz ₁ / Rz ₂ is less than 1.5, the chamfered portion is not sufficiently polished, and the effect of increasing the breaking strength around the end surface due to the formation of the chamfered portion is reduced. In contrast, when the Rz ₁ / Rz ₂ exceeds 10.0, the time required for the particular polishing of the chamfered portion is prolonged, the productivity is lowered, the roughness difference between the chamfered portion and the end face There is a risk that damage due to a new stress concentration is induced at the boundary between both surfaces. Therefore, if Rz ₁ / Rz ₂ is within the above numerical range, these problems do not occur.

Moreover, it is preferable that the average length RSm ₂ of the roughness curve element of the specific polished surface satisfies the relationship of RSm ₂ ≧ 100 μm.

Even in such a case, in the same manner as described above, the microscopic chips and cracks existing before the polishing are appropriately removed on the specific polished surface of the chamfered portion formed in the boundary portion, and the boundary Problems such as breakage of the glass substrate starting from the portion and generation and retention of glass particles at the boundary portion can be more effectively avoided. In particular, when RSm ₂ ≧ 100 μm, the crevice unevenness interval (cycle) of the chamfered portion is increased and the surface area is suppressed, so that the remaining amount of grinding fluid containing a large amount of glass particles is reduced, and the post-process The problem that glass particles adhere to the effective surface (surface) is effectively avoided. In this case, the ratio of the average lengths of the roughness curve elements, that is, RSm ₁ / RSm ₂ is preferably 0.1 or more and 0.7 or less. That is, when RSm ₁ / RSm ₂ is less than 0.1, an end face having a very small interval between the undulations and an extremely large chamfered portion are adjacent to each other, and the difference in surface properties between the two becomes large. Since the surface properties change abruptly at the boundary between the two, a new breakage starting point occurs at the boundary. On the other hand, when RSm ₁ / RSm ₂ exceeds 0.7, the difference in waviness unevenness between the end face and the chamfered portion is reduced, and as a result, the unevenness is efficiently made by the specific polishing process. It is not removed well, and the effect of increasing the breaking strength is insufficient. Therefore, if RSm ₁ / RSm ₂ is within the above numerical range, these problems do not occur.

  Further, in a cross section orthogonal to the longitudinal direction of the end surface, an angle α formed between a tangent to the front surface side of the specific polishing surface formed on the front surface side boundary portion and the front surface side, and a rear surface side boundary portion. It is preferable that the angle β formed between the tangent to the back surface side of the specific polishing surface to be formed and the back surface satisfies the relationship of 10 ° ≦ α ≦ 30 ° and 10 ° ≦ β ≦ 30 °, respectively.

  That is, as shown in FIG. 7 and FIG. 8 described above, by performing only the polishing of the end surface, the boundary between the end surface, the front surface, and the back surface has an uneven shape in plan view and the center of the surface. Even if it is formed biased to the center side of the side and the back side, if the above-mentioned angles α and β are not less than 10 ° and not more than 30 °, the specific polishing surface is surely ensured with a small amount of polishing so as to increase productivity. A chamfered portion can be formed. In this case, if the above-mentioned angles α and β are smaller than 10 °, the polishing region on the end face side in the chamfered portion is narrowed, and the chipping remaining on each boundary portion between the end face portion and the front surface and the back surface is reduced. Removal of cracks or chipping by specific polishing becomes insufficient. On the other hand, when the above angles α and β exceed 30 °, it is difficult to perform the specific polishing process in a manner including the boundary portion. Therefore, if the angles α and β are within the above numerical range, such a problem does not occur. From such a viewpoint, it is more preferable that the lower limits of the angles α and β are 15 ° and the upper limit is 20 °.

  The plate thickness T and the width W in the direction perpendicular to the longitudinal direction of the chamfered portion preferably satisfy the relationship of 200 μm ≦ T ≦ 1500 μm and 0.07 ≦ W / T ≦ 0.30.

  That is, for example, a glass substrate for FPD has a high required quality of the display surface. In particular, glass particles induce a display defect when forming a display image, so that adhesion of glass particles of several μm to several tens of μm becomes a problem. Therefore, miniaturization by chamfering each boundary portion between the end face after polishing and the front and back surfaces, where glass particles are likely to be generated during cleaning, is important. On the other hand, when the glass substrate breaks from the periphery of the end surface, the inventors have determined that the origin of breakage (origin) is around the boundary portion between the end surface and the front and back surfaces when only the end surface is polished, particularly the boundary portion. It was found that it was concentrated on the end face side within 100 μm (and further within 50 μm). This is because chips, cracks or chipping are concentrated in the range, and therefore it is necessary to preferentially remove this range by specific polishing. In that case, if W / T is less than 0.07, the specific polishing of the chamfered portion is insufficient, and the effect of increasing the end face strength due to the formation of the chamfered portion is reduced. On the other hand, when W / T exceeds 0.30, the time required for forming the chamfered portion is prolonged, and the productivity is lowered. Therefore, if W / T is within the above numerical range, such a problem does not occur. From such a viewpoint, more preferably, for example, in the case of a glass substrate for FPD (particularly for LCD) having a plate thickness T of 700 μm, the width W of the chamfered portion is 70 to 140 μm (0.10 ≦ W / T ≦ 0.20). Furthermore, the positional relationship between both ends in the direction perpendicular to the longitudinal direction of the chamfered portion formed thereafter is determined from the reference position, with the respective boundary portions between the end surface and the front and back surfaces when only the end surface is polished as the reference position. It is preferable that W1> W2> 0, where W1 is the dimension to the chamfered end on the end face side, and W2 is the dimension from the reference position to the chamfered end on the center side of the front and back surfaces. By doing so, the amount of polishing on the end face side including the boundary portion and easily inducing damage increases, so that the strength around the end face can be increased efficiently. From such a viewpoint, it is more preferable that 1.3 ≦ W1 / W2 ≦ 9.0.

  In addition, it is preferable that the chamfered portion is formed over the entire side of the glass substrate having the above configuration. However, for a glass substrate having a thin plate thickness, considering the difficulty of the specific polishing treatment of the chamfered portion. Then, the vicinity of the corner portion may be excluded from the chamfered portion. And the glass substrate which finished the specific grinding | polishing process of the chamfering part after grinding | polishing of an end surface is sent to a washing | cleaning process and an inspection process with conveyance after that, and is finally packed in a glass maker. In addition, the packed glass substrate is transferred to a panel manufacturing process for manufacturing an FPD by a display manufacturer or the like, for example, and the glass substrate is also transported in this process. In these transport processes, if the predetermined chamfered portion is formed between the end surface and the back surface of the glass substrate, when the glass substrate is transported on a transport roller or the like, the back surface and the end surface The situation that a defect or breakage occurs starting from the boundary portion of is effectively avoided.

  Furthermore, it is possible to form the predetermined chamfered portion not only between the end surface and the back surface of the glass substrate but also between the end surface and the surface, from the viewpoint of conveyance in addition to the measures against the glass particles described above. preferable. That is, in the transport process, the glass substrate is lifted and transferred using a plurality of forks, pins, etc., but particularly in the case of a large plate, the glass substrate is bent by weight, and the surface side of the end surface and There is a risk of stress concentration on both sides of the back surface, leading to breakage. In addition, when the glass substrate is at a high temperature, due to thermal stress, thermal stress concentration is likely to occur around the edge surface with the lowest strength, particularly the boundary between the edge surface and the front and back surfaces, which may cause damage. . Considering these circumstances, the significance of forming the predetermined chamfered portion between both the end surface of the glass substrate and the front surface and the back surface is increased.

  On the other hand, the method according to the present invention created in order to solve the above technical problem is a method of manufacturing the glass substrate according to the present invention described above, and a rough polishing process is performed on the end surface of the glass substrate. A finish polishing process is performed later to form a polishing surface that protrudes outward from the outer peripheral edge of each of the front and back surfaces to the central portion in the plate thickness direction, and then each of the end surface, the front surface, and the back surface is formed. It is characterized in that at least one of the boundary portions is subjected to a specific polishing process using a polishing tool having a finer particle size than the final polishing process.

  According to such a method, the end face of the glass substrate can be polished efficiently in a short time by rough polishing and finish polishing, for example, in a substantially arc-shaped cross section, and the end face is further polished at a finer grain size as subsequent polishing. The chamfered portion is not polished to the same shape with a tool, but a chamfered portion is formed with a finer-grained polishing tool at at least one of the boundary portions between the end surface and the front and back surfaces. Therefore, the end face strength can be efficiently improved by optimizing the three kinds of surface properties of the end face, the chamfered portion, and the front surface and / or the back surface. And, preferably, by arranging a polishing tool for performing rough polishing processing of the end surface, a polishing tool for performing final polishing processing of the end surface, and a polishing tool for performing specific polishing processing on the same path, Each polishing tool can perform each polishing process while continuously moving relatively linearly, and compared with the case where each chamfering process is performed separately, the processing time is greatly shortened and productivity is improved. Can be achieved. Furthermore, preferably, the surface property of the chamfered portion is made suitable by pressing the polishing tool for performing a specific polishing treatment with the boundary portion of the glass substrate in a state where the polishing tool is elastically supported using an elastic body such as a spring. can do.

  Furthermore, a method according to the present invention created to solve the above technical problem is a method of manufacturing the glass substrate according to the present invention described above, and a rotating shaft is used as the polishing tool for the specific polishing process. Using a rotary polishing tool having an orthogonal polishing surface, and forming the roughness of the outer peripheral portion of the polishing surface smaller than the roughness of the inner peripheral portion, and the end surface after polishing and the front and back surfaces of the glass substrate The rotary polishing tool rotates about the rotation axis while relatively linearly moving in the longitudinal direction with respect to at least one of the boundary portions of both of the outer peripheral portion and the inner peripheral portion of the polishing surface. Is characterized by forming a chamfered portion comprising the specific polished surface.

  According to such a method, the polishing surface (abrasive surface) of the rotary polishing tool is orthogonal to the rotation axis, and the roughness of the outer peripheral portion of the polishing surface is smaller than the roughness of the inner peripheral portion. When the specific polishing process for the boundary portion is performed by rotating the rotary polishing tool around the rotation axis while linearly moving relative to the boundary portion of the glass substrate, first, the outer periphery having a small roughness on the polishing surface. By the portion, the boundary portion is finely cut (fine polishing) to obtain a so-called “running” effect. Thereby, in the initial stage of the specific chamfering process for the boundary portion of the glass substrate, unreasonable stress concentration is suppressed, and occurrence of chipping (initial chipping) or cracks due to flapping of the glass substrate is suppressed, A chamfered surface corresponding to the initial stage is formed at the boundary portion. Thereafter, as the next stage, the rotary polishing tool relatively linearly moves, so that the inner peripheral portion having a large roughness on the polished surface comes into contact with the chamfered surface corresponding to the initial stage described above, and the relative roughening is performed. Polishing is performed. Since this relative rough polishing increases the speed of polishing, the chamfering processing time is shortened, and at the start of the relative rough polishing, the boundary portion is finely polished to perform the above-described “running”. Therefore, the relative rough polishing is smoothly started and proceeds without causing the occurrence of cracks, cracks, or the like or the extension thereof. After this, as a final step, the rotary polishing tool further moves relatively linearly, so that the outer peripheral portion having the above-mentioned small roughness on the polishing surface comes into contact with the chamfered surface that has been subjected to relative rough polishing, and finishes. Polishing is performed. As a result, the occurrence of chipping or cracking at the rear end of the chamfered surface due to the vibration of the rotary polishing tool acting on the chamfered surface from the rear end in the moving direction of the polishing surface is suppressed, and due to relative rough polishing. Thus, the fine grinding powder or glass powder remaining on the chamfered surface is removed. As described above, a series of polishing processes including fine polishing (relative polishing), relative rough polishing, and final polishing are performed along the relative linear movement of a single rotary polishing tool. Since it is possible to perform specific chamfering processing in a short time while suppressing the occurrence of chipping, cracks, etc., it is possible to simplify the equipment and ensure good quality around the chamfered part. As a result, productivity can be greatly improved. It should be noted that either one or both of the rotary polishing tool and the glass substrate may be linearly moved. However, in the case of a large glass substrate having a longitudinal dimension of the boundary portion of the glass substrate of 1000 mm or more, the glass substrate It is advantageous to move the rotating polishing tool in the longitudinal direction of the boundary portion while the tool is fixed on the work table or the like. It is advantageous to move the substrate linearly across the polishing surface. And preferably, the surface property of the chamfered portion can be made suitable by bringing the rotary polishing tool into elastic contact with an elastic body such as a spring and pressing it against the boundary portion of the glass substrate. .

  As described above, according to the present invention, the productivity is improved and an appropriate chamfered portion is reliably formed at the boundary between the polished end surface of the glass substrate and the front surface and / or the back surface. The relationship between the surface properties of the end surface of the glass substrate and the surface properties of the chamfered portion formed at the front surface and / or back surface side of the end surface is optimized, and the glass substrate is effectively damaged or broken. In addition, problems such as glass particles are avoided, and the quality of the glass substrate is improved.

It is the principal part expanded vertical sectional view which cut | disconnected the glass substrate which concerns on embodiment of this invention in the direction orthogonal to the longitudinal direction of an end surface. It is the schematic which shows the glass substrate obtained by cut | disconnecting a glass original plate, and the polishing tool which grind | polishes the end surface part of the glass substrate. It is a longitudinal cross-sectional view which shows the principal part of the glass substrate which performed only the end surface grinding | polishing process. It is a schematic front view which shows the state which is performing the chamfering process with respect to the glass substrate after an end surface process. It is a schematic plan view which shows the state which is performing the chamfering process with respect to the glass substrate after an end surface process. It is a schematic plan view which shows the principal part of the glass substrate after a chamfering process. It is a schematic plan view which shows the principal part of the glass substrate which shows the conventional problem. It is a longitudinal cross-sectional view which shows the principal part of the glass substrate which shows the conventional problem. It is a graph which shows the conventional problem.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. In the following embodiments, a glass substrate for FPD typified by LCD is targeted.

  FIG. 1 is an enlarged longitudinal sectional view of a main part of the glass substrate 1 according to the present embodiment. In addition, although the figure has shown only the form of the surface 2a side part of the glass substrate 1, the back side part has also comprised the form which becomes symmetrical on both sides of the plate | board thickness direction center line X. As shown in the figure, the glass substrate 1 has a planar surface 2a, an end surface 3 having a convex arcuate cross section, and a planar chamfer formed between the surface 2a and the end surface 3. Part 4.

In this embodiment, the end surface 3 of the glass substrate 1 is a polished surface that has been subjected to a final polishing process after being subjected to a rough polishing process, and the surface 2a is a molded surface, that is, an unpolished surface, and a chamfered portion. Reference numeral 4 denotes a specific polished surface that has been subjected to a specific polishing process after the finish polishing of the end face 3. The ten-point average roughness Rz ₂ of the specific polished surface of the chamfered portion 4 is smaller than the ten-point average roughness Rz ₁ of the end surface 3 and the average length of the roughness curve elements of the specific polished surface of the chamfered portion 4 The thickness RSm ₂ is set larger than the average length RSm ₁ of the roughness curve element of the polished surface of the end face 3. The surface 2a, since a mirror surface, the average roughness thereof ten-point is smaller than the ten-point average roughness Rz ₂ of the particular polished surface of the chamfered portion 4, and an average length of roughness curve element of Is larger than the average length RSm ₂ of the roughness curve element of the specific polished surface of the chamfered portion 4.

In this case, the 10-point average roughness Rz ₂ of the specific polished surface of the chamfered portion 4 is 1.5 μm or less, and Rz ₁ / Rz which is a ratio to the 10-point average roughness Rz ₁ of the polished surface of the end face 3. ₂ is 1.5 or more and 10.0 or less. Further, the average length RSm ₂ of the roughness curve element of the specific polished surface of the chamfered portion 4 is 100 μm or more, and is the ratio RSm ₁ to the average length RSm ₁ of the roughness curve element of the polished surface of the end face 3. ₁ / RSm ₂ is and 0.7 or less 0.1 or more.

  Furthermore, in the cross section shown in FIG. 1 (cross section perpendicular to the longitudinal direction of the end face 3), the angle α formed between the tangent line A to the surface 2a side of the chamfered portion 4 and the surface 2a is 10 ° or more and 30 ° or less. (In this embodiment, the angle between the tangent to the back surface side and the back surface is 10 ° or more and 30 ° or less (not illustrated). 18 °).

  In this case, the chamfered portion 4 removes the periphery of the boundary portion z between the surface 2a and the end surface 3 (part indicated by a broken line in FIG. 1) in a state where the polishing process of the end surface 3 has been performed by a specific polishing process. The removal portion is a region having a width W1 from the boundary portion z to the end face 3 side of 70 μm and a width W2 from the boundary portion z to the surface 2a side of 30 μm. The angle γ formed between the tangent line B of the boundary z and the surface 2a is 25 ° in the present embodiment.

  Further, the glass substrate 1 has a thickness T of 200 μm or more and 1500 μm or less, and a width W of the chamfered portion 4 (a dimension in a direction orthogonal to the longitudinal direction (direction along the side) of the chamfered portion 4). W / T, which is the ratio of the thickness to the plate thickness T, is set to be 0.07 or more and 0.30 or less.

  The glass substrate 1 having the above configuration is manufactured as follows.

  FIG. 2 shows a substantially rectangular glass substrate 1 obtained by putting scribes at four locations on the surface of the glass original plate after molding, and folding the glass original plate starting from the scribe marks, and folding the glass substrate 1 A polishing tool 5 for polishing the cracked end surface portion 3a is illustrated. The end surface portion 3a of the glass substrate 1 is first subjected to a rough polishing process using a first polishing tool, and then a final polishing process using a second polishing tool. As shown in FIG. 2, the first polishing tool is a rough polishing rotary grindstone wheel (metal) that is formed by attaching a diamond abrasive grain layer held by a metal bond to an outer peripheral surface having a concave arc shape when viewed from the front. Bond diamond wheel). Then, with the first polishing tool pressed against the end surface portion 3a of the glass substrate 1, the first polishing tool is relatively moved in the longitudinal direction (direction along the side) of the end surface portion 3a of the glass substrate 1. Rough polishing is performed. The second polishing tool is a grinding wheel for finishing polishing (resin bond wheel) having the same shape as the first polishing tool, and fine abrasive grains such as silicon carbide bonded to the outer peripheral surface thereof with polyurethane resin or the like. The second polishing tool is subjected to a final polishing process by moving in the same manner as described above while being pressed against the end surface of the glass substrate 1 subjected to the rough polishing process. As a result, as shown in FIG. The glass substrate 1 is formed with an end face 3 having a substantially arc-shaped cross section having a ten-point average roughness Rzjis of about 1 to 3 μm. The formation of the end face 3 of the glass substrate 1 is not limited to the two-stage polishing process as described above, and may be performed by a three-stage or more polishing process.

  As described above, when the end surface 3b having a substantially arc-shaped cross section is formed on the glass substrate 1, the boundary portion z between the end surface 3b and the surface 2a, and the boundary portion z between the end surface 3b and the back surface 2b, In a plan view, the concave and convex shape is as indicated by reference numeral z1 in FIG. After becoming such a form, the chamfered portion 4 is formed by performing a specific polishing process on the boundary portion z of the glass substrate 1 using the third polishing tool 6. As shown in FIG. 4, the third polishing tool 6 has a flat polishing surface (abrasive surface) 6b orthogonal to the rotation shaft 6a. The polishing surface 6b is finer than the second polishing tool. It is made of abrasive grains. The glass substrate 1 is set on the upper surface of the work table (surface plate) 7 with the periphery of the end surface 3 protruding.

  Then, while simultaneously pressing and rotating the polishing surface 6b of the two third polishing tools 6 against the boundary z on the front surface 2a side and the boundary z on the back surface 2b side of the glass substrate 1, the third polishing tool The specific polishing process is performed by relatively moving 6 in the longitudinal direction of the boundary portion z of the glass substrate 1. Thereby, a large number of glass chippings and the like remaining at the boundary z of the glass substrate 1 are removed. In this case, the angles formed between the polishing surfaces 6b of the two third polishing tools 6 and the front surface 2a and the back surface 2b of the glass substrate 1 are each set to 10 ° or more and 30 ° or less (18 ° in this embodiment). . Preferably, as shown in FIG. 5, the third polishing tool 6 is a concave portion having a circular central portion, and an inner peripheral side polishing portion 6 ba having a relatively small roughness so as to surround the concave portion, and the roughness Are arranged with a relatively large outer peripheral side polishing portion 6bb, and the boundary portion z of the glass substrate 1 is subjected to a specific polishing treatment by both of the polishing portions 6ba and 6bb. Note that the two third polishing tools 6 are spaced apart from each other in the relative movement direction.

  Then, by completing this specific polishing treatment, as shown in FIG. 6 (and FIG. 1), a chamfered portion 4 formed by completely removing the boundary portion z between the surface 2a and the end surface 3 of the glass substrate 1 is obtained. It is formed. By forming the chamfered portion 4, the breaking strength of the end surface 3 is increased, and problems such as glass particles or glass chipping are avoided.

  In order to confirm the effects of the glass substrate illustrated in FIG. 1, the present inventors performed comparison between Examples 1 to 5 of the present invention and Comparative Examples 1 to 3 as follows. . In each of these Examples and Comparative Examples, OA-10 manufactured by Nippon Electric Glass Co., Ltd., which was molded by the overflow downdraw method, was used as the glass original plate.

  For Examples 1 to 3 and Comparative Examples 1 and 2 of the present invention shown in Table 1 below, as a sample to be used, a glass original plate having a plate thickness of 700 μm is folded and divided along a scribe mark, whereby a short side dimension is obtained. A glass substrate having a length of 1500 mm and a long side dimension of 1800 mm was obtained. Similarly, in Examples 4 and 5 and Comparative Example 3, as a sample to be used, a glass original plate having a thickness of 500 μm is folded and divided along a scribe mark so that the short side dimension is 550 mm and the long side dimension. Obtained a glass substrate of 670 mm. Then, with respect to the end surface portions of these glass substrates, a polishing process for forming an end surface having a circular arc shape with a convex cross section, and a chamfered portion at each boundary portion between the end surface, the front surface, and the back surface after the polishing The specific polishing treatment for forming the film was performed according to the following procedure.

  Regarding Examples 1 to 3 and Comparative Examples 1 and 2 of the present invention, first, a rough polishing as a first polishing tool having the form shown in FIG. 2 in a state where a glass substrate is placed on a surface plate and fixed by suction. The outer peripheral surface of the polishing grindstone (abrasive grain # 400) is brought into pressure contact with the end surface portion of the glass substrate and linearly moved at the grinding speed shown in Table 1 to obtain an end surface portion that is a rough surface having a substantially arc-shaped cross section. Formed. Next, similarly, the outer peripheral surface of the rotary grindstone for finishing polishing (abrasive grain # 1000) as the second polishing tool having the form shown in FIG. 2 is brought into pressure contact with the end surface portion after rough polishing of the glass substrate, and Table 1 The end face finished and polished into a substantially circular arc shape was formed by linear movement at the grinding speed shown in FIG. Further, in Examples 4 and 5 and Comparative Example 3 of the present invention, first, the glass substrate is linearly moved at the grinding speed shown in Table 2 while being fixedly arranged at a fixed position as shown in FIG. The outer peripheral surface of the rotating grindstone for rough polishing (abrasive grain # 400) as a polishing tool was brought into pressure contact with the end surface portion of the glass substrate, thereby forming an end surface portion that was a rough surface having a substantially arc-shaped cross section. Next, similarly, while rotating the glass substrate linearly at the grinding speed shown in Table 2, the final polishing rotary grindstone (abrasive grain # 1000) as the second polishing tool having the form shown in FIG. ) Was pressed into contact with the end surface of the glass substrate after rough polishing to form an end surface that was finished and polished into a substantially circular arc cross section.

  Thereafter, a specific polishing process was performed with a third polishing tool on each boundary portion between the end surface, the front surface, and the back surface of the glass substrate. As the third polishing tool, there was used a flat diamond polishing plate in which diamond abrasive grains were dispersed in a resin material on a circular base. In addition, the magnitude | size of said abrasive grain and the magnitude | size of the abrasive grain shown to Table 1, 2 are based on JISR6001: 1998.

  When performing the specific polishing process, the angle formed by the front and back surfaces of the glass substrate and the tangent line of the chamfered portion (angle α in FIG. 1; the same applies to the back surface side) is 18 ° to 22 ° as appropriate. After adjusting the angle of the 3 polishing tool, a grinding liquid (grinding water) was supplied to the contact surface between the third polishing tool and the glass substrate. Then, while rotating the third polishing tool (polishing plate) at a peripheral speed of 2000 m / min so as to obtain a desired chamfer dimension, it is linearly moved at different grinding speeds as shown in Tables 1 and 2, and near the corner portion. A specific polishing treatment was performed over the entire outer periphery of the glass substrate except for. As described above, glass substrates of Examples 1 to 3 and Examples 4 and 5 were obtained.

  In Examples 1, 2, and 4, the abrasive grains of the third polishing tool are # 3000, and in Examples 3 and 5, the abrasive grains of the third polishing tool are # 2000, whereas in Comparative Examples 1 to 3. Without performing the specific polishing process with the third polishing tool, only the rough polishing process with the first polishing tool and the final polishing process with the second polishing tool were performed on the end surface portion of the glass substrate. In all the examples, the moving speed and grinding conditions of the third polishing tool are selected so that the chamfer dimension (chamfer width) is in the range of 60 to 200 μm, and all the end surfaces of the glass substrate as a sample are selected. A substantially flat chamfered portion was formed at the boundary between the front surface and the back surface.

  In addition, in the above Example, after forming a substantially circular-arc-shaped grinding | polishing surface in the end surface part of a glass substrate, the method of forming a chamfering part in the boundary part with the surface of an end surface, and a back surface using a 3rd polishing tool. However, the first polishing tool, the second polishing tool, and the third polishing tool are installed on the same traveling rail in a state where the glass substrate is sucked and fixed on the surface plate, and simultaneously along the traveling rail. You may make it complete | finish polishing operation | movement continuously by making 3 types of grinding | polishing tools drive | work. In this way, since all polishing processes are completed in a shorter time, the processing efficiency can be remarkably increased, and in the polishing process step of a large-sized glass substrate having a dimension of each side of 1000 mm or more. The handling becomes easy. For glass substrates with small sizes, three types of polishing tools are installed so as to be parallel to the sides of the glass substrate, and each glass substrate is continuously polished while being transported using a transport means such as a transport belt. You may use the method of performing.

On the other hand, about each glass substrate of Examples 1-5 and Comparative Examples 1-3, roughness measurement is performed with a measurement length of 5.0 mm using a surfcom 590A manufactured by Tokyo Seimitsu Co., Ltd., and glass is measured according to JIS B0601: 2001. The roughness parameters of the ten-point average roughness Rzjis (Rz ₁ , Rz ₂ ) and the average length RSm (RSm ₁ , RSm ₂ ) value of the roughness curve element of the end face and chamfered portion of the substrate were calculated. The ten-point average roughness Rz ₁ and Rz ₂ and the average lengths RSm ₁ and RSm ₂ of the roughness curve elements were subjected to chamfering treatment on 10 glass substrates under the same conditions, and 10 times for each. Measurements were made and evaluated by calculating the average value. The results are shown in Tables 1 and 2 below.

  About the intensity | strength of the glass substrate after grinding | polishing, the fracture strength was measured by the three-point bending test method using Orientec Tensilon RTA-250. For the sample of the bending test, a test piece obtained by cutting out the central part of the side of the end face of the glass substrate into a size of 80 × 15 mm is used, and the load is applied with the apex of the end face (the apex of the substantially arc of the cross section) facing upward. The fracture stress (end face strength) σ was measured by applying the load, measuring the load at the time of breakage, and calculating by the equation shown in the following formula 1.

  In the equation expressed by the above equation 1, P is a breaking load, L is a distance between fulcrums, B is a sample width, and h is a glass thickness.

  In Tables 1 and 2 below, the breaking stress of the glass substrate is described, and these are measured for 10 breaking stresses of each Example and each Comparative Example, and the minimum value (the one with the smallest strength) is measured. ). Furthermore, in order to evaluate the adhesion characteristics of the glass particles adhering to or remaining on the surface of the glass substrate, the glass remaining on the surface of the glass substrate after washing and drying each glass substrate of each Example and each Comparative Example The surface particle value per sheet was measured. For the particle value, the number of particles of 1 μm or more was measured using a particle measuring device GI-7200 manufactured by Hitachi High-Technologies Corporation, and the numerical value was converted to the number per square meter. The results are shown in Tables 1 and 2 below. Further, with respect to each glass substrate of each example and each comparative example, the remaining state of the step due to chipping at the boundary portion between the front surface and the back surface of the end face was magnified and observed with a microscope. The results are shown in Tables 1 and 2 below. In this case, in Tables 1 and 2, “○” indicates that no chipping level difference is observed, “Δ” indicates that a small level difference is observed, and “×” indicates a large level level remaining. Indicates what is observed.

  Note that the angle α (see FIG. 1) between the surface of the glass substrate and the tangent to the surface side of the chamfer adjacent to the surface of the glass substrate during the specific polishing process of the chamfered portion, and the back surface of the glass substrate and the chamfered portion adjacent thereto. Table 3 below shows the actual measurement value of the angle β formed by the tangent to the back surface side and the measured value of the width W of the chamfered portion.

  According to Tables 1 and 2 above, it is obvious that any of Examples 1 to 5 of the present invention has a small ten-point average roughness at the boundary between the front surface and the back surface of the glass substrate and is close to a mirror surface. That is, a chamfered portion having a sufficient width is formed, and a remarkably high fracture strength (that is, the end surface strength exceeds 160 MPa) as compared with a glass substrate not formed with a chamfered portion as in the comparative example. It was confirmed to have. Further, in the chamfered portion of each example, no step or minute crack at the polishing boundary due to chipping was confirmed, and it was confirmed that good or extremely good results were exhibited in all of the adhesion of glass particles and the like.

  Therefore, the glass substrate according to the embodiment of the present invention hardly induces breakage in the post-process, becomes extremely high strength, and generates very little glass particles due to the end face. Even when used in a high-resolution display such as an organic EL, it is possible to effectively suppress a disconnection defect or the like that occurs when a display element or device is formed on a glass substrate.

  In the case of the embodiment of the present invention, even if the grinding speed is increased from 100 mm / min to 400 mm / min, the same chamfered portion can be efficiently formed by appropriately selecting the polishing plate of the polishing tool and setting the grinding conditions. Can be obtained, and the efficiency of the process can be improved.

  On the other hand, in the comparative example, not only when the moving speed of the polishing tool is 200 mm / sec or 400 mm / sec, but even when the polishing tool is slowed down to 100 mm / sec, the minimum fracture strength of the end face is relatively low, and the end face with low strength There is a risk of causing breakage due to contact of the conveying means to the part or concentration of thermal stress. In any of the comparative examples, since the particle value is relatively high and the chipping level difference at the boundary is large, for example, in the process such as cleaning, drying, transporting, and packing, the glass is higher than the chipping part at the boundary. Particles may peel off and adhere to the glass substrate, causing a disconnection failure when forming a display element or device. Therefore, it was confirmed that the glass substrate according to each example of the present invention was extremely excellent in both the breaking strength and the glass particle as compared with the glass substrate according to these comparative examples.

DESCRIPTION OF SYMBOLS 1 Glass substrate 2a Front surface 2b Back surface 3 End surface 4 Chamfer part 5 Polishing tool (1st, 2nd polishing tool)
6 Third polishing tool 6a Rotating shaft 6b of third polishing tool Polishing surface (abrasive surface) of third polishing tool
6ba Inner peripheral part 6bb of the polishing surface (abrasive surface) of the third polishing tool Ab Outer peripheral part A of the polishing surface (the abrasive surface) of the third polishing tool A Tangent line z to the surface side of the chamfered part Boundary part

Claims (7)

It has a front surface, a back surface, and an end surface existing between the outer peripheral edges of the front surface and the back surface. For a glass substrate on which a polished surface protruding to
A chamfered portion made of a specific polished surface is formed by performing a specific polishing process different from the polishing process on at least one of the boundary portions between the end face after the polishing process and the front surface and the back surface,
The chamfer ten-point average roughness Rz ₂ of the particular polished surface of the particular polishing process is smaller than the ten-point average roughness Rz ₁ of the polishing surface of said end faces have not been subjected and,
The average length RSm ₂ of the roughness curve element of the specific polishing surface of the chamfered portion is larger than the average length RSm ₁ of the roughness curve element of the polishing surface of the end face not subjected to the specific polishing treatment. Characteristic glass substrate. The ten-point average roughnesses Rz ₂ and Rz ₁ of the specific polished surface satisfy Rz ₂ ≦ 1.5 μm and satisfy a relationship of 1.5 ≦ Rz ₁ / Rz ₂ ≦ 10.0. The glass substrate according to claim 1. 3. The glass substrate according to claim 1, wherein an average length RSm ₂ of the roughness curve element of the specific polished surface satisfies a relationship of RSm ₂ ≧ 100 μm.   In a cross section orthogonal to the longitudinal direction of the end face, an angle α formed between the tangent to the front surface side of the specific polishing surface formed at the front surface side boundary portion and the front surface, and a rear surface side boundary portion are formed. The angle β formed between the tangent to the back surface side of the specific polishing surface and the back surface satisfies a relationship of 10 ° ≦ α ≦ 30 ° and 10 ° ≦ β ≦ 30 °, respectively. The glass substrate in any one of 1-3.   The thickness W and the width W in the direction perpendicular to the longitudinal direction of the chamfered portion satisfy the relationship of 200 μm ≦ T ≦ 1500 μm and 0.07 ≦ W / T ≦ 0.30. The glass substrate in any one of.   A method for producing the glass substrate according to any one of claims 1 to 5, wherein the outer peripheral edge of each of the front surface and the rear surface is subjected to a final polishing treatment after performing a rough polishing treatment on the end surface of the glass substrate. Forming a polishing surface that protrudes outward from the central portion in the plate thickness direction, and then, at least one of the boundary portions between the end surface, the front surface, and the back surface, has a finer particle size than the finish polishing treatment. A method for producing a glass substrate, comprising performing a specific polishing treatment using a polishing tool having the same.   A method for producing a glass substrate according to any one of claims 1 to 5, wherein a rotating polishing tool having a polishing surface orthogonal to a rotation axis is used as the polishing tool for the specific polishing process, and the polishing is performed. The rotary polishing tool is formed so that the roughness of the outer peripheral portion of the surface is smaller than the roughness of the inner peripheral portion, and at least one of the boundary portions between the end surface after polishing and the front and back surfaces of the glass substrate. Is rotated around the rotation axis while linearly moving in the longitudinal direction thereof, thereby forming a chamfered portion made of the specific polishing surface by both the outer peripheral portion and the inner peripheral portion of the polishing surface. A method for manufacturing a glass substrate.

Images