Method for manufacturing glass plates and method for inspecting glass plates

Abstract

Provided is a glass plate production method comprising: a collection step for collecting a sample glass plate 2 from a glass plate production line; and an inspection step for carrying out an inspection using a main surface 2a of the sample glass plate 2, wherein a preservation step for preserving the state of a main surface 2a by affixing main surfaces 2a of collected sample glass plates 2 to each other or by affixing a main surface 2a of a collected sample glass plate to an affixation surface of a prepared protective glass plate is provided between the collection step and the inspection step.

Description

Technical Field

[0001] The present disclosure relates to a method for manufacturing a glass plate and a method for inspecting a glass plate.

Background Art

[0002] As is well known, when manufacturing a glass plate, it is often the case that a sample glass plate is taken from among a large number of glass plates flowing on a production line and a predetermined inspection is performed on the glass plate.

[0003] In the above-described inspection, the inspection may be performed using one main surface (one of the front and back surfaces) of the glass plate. For example, Patent Document 1 discloses an inspection for measuring the thermal shrinkage rate of a glass plate. In this inspection, a mark serving as a reference for measuring the thermal shrinkage rate is formed on one main surface of the glass plate.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, the glass plate sampled as a sample is not always immediately subjected to inspection after sampling, and may be subjected to inspection after being stored due to process convenience or the like. In such a case, between sampling and the start of inspection, for example, the glass plate is stored in a state where it is placed on a pallet and packed.

[0006] However, when glass plates are stored in the manner described above, one main surface of the glass plate becomes contaminated by the packaging material during storage, which makes it difficult to perform subsequent inspections accurately. For example, as disclosed in Patent Document 1, when a mark is formed on one main surface for measuring the thermal shrinkage rate, contamination of the main surface makes it impossible to form a clear mark, which negatively affects the accurate measurement of the thermal shrinkage rate.

[0007] Furthermore, the problem of difficulty in accurate testing, as mentioned above, is not limited to tests measuring thermal shrinkage. It can also occur when testing glass plates after storage. For example, consider a test that analyzes the contamination adhering to one main surface of a glass plate taken as a sample. In this test, accurate analysis becomes difficult if the analysis is performed after storage. This is because new contamination adheres to one main surface of the glass plate during storage, so the state of contamination on one main surface differs between the time the glass plate is taken as a sample and the time when the contamination is actually analyzed after storage.

[0008] In light of the above circumstances, the technical challenge to be addressed is to enable accurate testing of a glass plate taken as a sample, even when the test is performed after storage following collection, by utilizing one of its main surfaces. [Means for solving the problem]

[0009] (1) A method for manufacturing a glass plate according to the present disclosure is a method comprising a sampling step of taking a sample glass plate from a glass plate manufacturing line and an inspection step of performing an inspection using one main surface of the sample glass plate, characterized in that a preservation step is provided between the sampling step and the inspection step to preserve the state of one main surface by bonding the two main surfaces of the sampled sample glass plates together, or by bonding one main surface of the sampled sample glass plate to the mating surface of a prepared protective glass plate.

[0010] In this manufacturing method, a storage step is included between the sampling step, in which a sample glass plate is taken from the glass plate production line, and the inspection step, in which an inspection is performed using one main surface of the sample glass plate. In the storage step, the state of one main surface is preserved by bonding the main surfaces of the collected sample glass plates together, or by bonding one main surface of the collected sample glass plate to the mating surface of a prepared protective glass plate. In other words, it is possible to prevent changes in the state of one main surface, such as the adhesion of new dirt to the main surface. As a result, accurate inspection is possible even when the sample glass plate is stored after sampling before being inspected.

[0011] (2) In the method of (1) above, in the storage step, it is preferable to pressurize the sample glass plates with a pressure of 0.5 Pa or more and 1.0 Pa or less when bonding the sample glass plates together.

[0012] In this way, the main surfaces of the sample glass plates can be bonded together more firmly, or one main surface to the other surface. Therefore, the condition of one main surface can be preserved for a longer period of time.

[0013] (3) In the method of (1) or (2) above, it is preferable that the surface roughness Ra of one main surface is 0.35 nm or less.

[0014] In this way, because one main surface is smooth, the two main surfaces, or one main surface and the mating surface, can be bonded together simply by bringing them into contact (adhering tightly) during the preservation process. Moreover, since the two main surfaces, or one main surface and the mating surface, adhere to each other to a degree that allows for separation, the inspection process can be carried out quickly after the preservation process. This is extremely advantageous for smoothly inspecting the sample glass plates.

[0015] (4) In any of the methods described in (1) to (3) above, the laminated sample glass plates may be placed on a pallet during the storage process.

[0016] When sample glass plates are stored on a pallet without bonding one main surface to another, or one main surface to a mating surface, measures such as bagging the sample glass plates are necessary to prevent new dirt from adhering to one main surface during storage. However, this manufacturing method prevents new dirt from adhering to one main surface as described above. Therefore, even when sample glass plates are placed on a pallet, the measures described above become unnecessary.

[0017] (5) In any of the methods (1) to (4) above, if the inspection step is a step to inspect the thermal shrinkage rate of the sample glass plate, the inspection step may involve drawing lines for inspecting the thermal shrinkage rate on one main surface.

[0018] (6) In any of the methods described in (1) to (4) above, the preservation step may involve bonding together the main surfaces of the collected sample glass plates to preserve the state of one main surface, and if the inspection step is a step to inspect for contamination of the sample glass plates, the inspection step may involve analyzing the dirt adhering to the main surface.

[0019] When drawing lines on one main surface to inspect the thermal shrinkage rate of a sample glass plate, or when analyzing dirt adhering to one main surface to inspect for contamination of a sample glass plate, the aforementioned functions and effects obtained by the glass plate manufacturing method described above can be favorably enjoyed.

[0020] (7) The glass plate inspection method according to the present disclosure is characterized by comprising a preservation step of preserving the state of one main surface by bonding one main surface of a sample glass plate to another, or by bonding one main surface of a sample glass plate to the mating surface of a protective glass plate, and an inspection step of performing an inspection using one main surface of a sample glass plate after the preservation step.

[0021] By doing so, it is possible to prevent the state of one main surface of the sample glass plate from changing, such as new dirt adhering to the one main surface, due to the execution of the storage process. As a result, accurate inspection is possible even when the sample glass plate is inspected after storage.

Effect of the Invention

[0022] According to the method for manufacturing a glass plate and the method for inspecting a glass plate according to the present disclosure, when performing an inspection using one main surface of a glass plate collected as a sample, accurate inspection is possible even when the inspection is performed after storage after collection.

Brief Description of the Drawings

[0023] [Figure 1] It is a diagram showing a sampling step in the method for manufacturing a glass plate. [Figure 2] It is a diagram showing a storage step in the method for manufacturing a glass plate. [Figure 3] It is a diagram showing a storage step in the method for manufacturing a glass plate. [Figure 4a] It is a diagram showing an inspection step (method for inspecting a glass plate) in the method for manufacturing a glass plate. [Figure 4b] It is a diagram showing an inspection step (method for inspecting a glass plate) in the method for manufacturing a glass plate. [Figure 4c] It is a diagram showing an inspection step (method for inspecting a glass plate) in the method for manufacturing a glass plate. [Figure 4d] It is a diagram showing an inspection step (method for inspecting a glass plate) in the method for manufacturing a glass plate. [Figure 4e] It is a diagram showing an inspection step (method for inspecting a glass plate) in the method for manufacturing a glass plate. [Figure 5a] It is a diagram showing a method for manufacturing a glass plate (comparative example). [Figure 5b] It is a diagram showing a method for manufacturing a glass plate (comparative example). [Figure 5c] It is a diagram showing a method for manufacturing a glass plate (comparative example). [Figure 5d]This figure shows a method for manufacturing a glass plate (comparative example). [Figure 5e] This figure shows a method for manufacturing a glass plate (comparative example). [Figure 6] This figure shows a method for manufacturing a glass plate (comparative example). [Modes for carrying out the invention]

[0024] The method for manufacturing a glass plate according to this embodiment will be described below with reference to the attached drawings.

[0025] <First Embodiment> The method for manufacturing a glass plate according to the first embodiment comprises, in chronological order, a sampling step shown in Figure 1, a storage step shown in Figures 2 and 3, and an inspection step (glass plate inspection method) shown in Figure 4. In this embodiment, a sample glass plate 2 taken from a large number of glass plates 1 in the sampling step is stored for a predetermined storage period while the storage step is performed, and then an inspection is conducted in the inspection step to measure the thermal shrinkage rate.

[0026] The sampling process shown in Figure 1 is the process of taking a sample glass plate 2 from the glass plate manufacturing line. The glass plate manufacturing line in this embodiment is a manufacturing line for glass plates used as glass substrates or cover glass in various displays (for example, liquid crystal displays and organic EL displays). Such glass plates are formed using methods such as the overflow method or the float method.

[0027] In the sampling process, sample glass plates 2 are randomly selected from a group G of glass plates 1 flowing along the manufacturing line. Of course, sample glass plates 2 may also be selected at regular intervals from the large number of glass plates 1 lined up on the manufacturing line. Note that the large number of glass plates 1 are manufactured under the same conditions. In this embodiment, an even number of glass plates 1 are selected as sample glass plates 2. Of course, the number of glass plates 1 selected as sample glass plates 2 is not particularly limited and may include an odd number. If the size of the glass plate 1 is large, a glass plate of a predetermined size may be cut from the selected glass plate 1, and the cut glass plate may be used as sample glass plate 2.

[0028] The preservation process shown in Figures 2 and 3 involves bonding together two main surfaces 2a of the collected sample glass plates 2 to preserve the state of each main surface 2a. This preservation process prevents changes in the state of each main surface 2a, such as the adhesion of new dirt (dirt that was not present when the sample glass plates 2 were collected). It is preferable that the preservation process be continued from the completion of the sampling process until the start of the inspection process.

[0029] Here, "one main surface 2a" refers to one of the front and back surfaces of the sample glass plate 2. In this embodiment, the surface that serves as the guaranteed surface is designated as the one main surface 2a. The "guaranteed surface" is the surface of the front and back that has relatively fewer opportunities to come into contact with rollers, etc., during the manufacturing process, and is relatively free of scratches and dirt, making it suitable for film deposition treatment. Of course, the surface on the back side of the guaranteed surface (the non-guaranteed surface) may also be designated as the one main surface 2a.

[0030] In the preservation process, as shown in Figure 2, two sample glass plates 2 of approximately the same dimensions are bonded together by directly contacting (adhering tightly to) one main surface 2a of the two sample glass plates 2. At this time, the main surfaces 2a are bonded together without misalignment so that the edges of the two main surfaces 2a are aligned. As a result of this bonding, the two sample glass plates 2 become one unit, forming a laminate 3. Note that the sample glass plates 2 may also be provided with an orientation flat to determine their orientation (see Figure 3).

[0031] In this embodiment, siloxane bonds are used to bond two main surfaces 2a of the sample glass plate 2 together. For siloxane bonds to be used, it is preferable that the main surfaces 2a of the sample glass plate 2 be as smooth and clean as possible. Therefore, in this embodiment, the surface roughness Ra of the main surfaces 2a is controlled to be 0.35 nm or less. More preferably, the surface roughness Ra of the main surfaces 2a is 0.3 nm or less, and even more preferably 0.2 nm or less. Furthermore, in this embodiment, the particle count of the main surfaces 2a is 1500 pcs / m 2 The following applies: The number of particles on one main surface 2a is more preferably 1000 pcs / m 2 More preferably, 500 pcs / m 2 The following applies. Here, the number of particles can be measured using, for example, a surface particle measuring instrument (GI 3200) manufactured by Hitachi High-Technologies Corporation.

[0032] Furthermore, when bonding the two main surfaces 2a of the sample glass plates 2 together, pressure may be applied to the sample glass plates 2 in a direction perpendicular to the main surface 2a. The lower limit of the pressure applied is preferably 0.5 Pa or more, more preferably 0.7 Pa or more, and the upper limit is preferably 1.0 Pa or less, more preferably 0.9 Pa or less. This allows the two main surfaces 2a of the sample glass plates 2 to bond together more firmly. Therefore, the condition of the main surface 2a can be preserved for a longer period of time.

[0033] The bonding of the two main surfaces 2a of two sample glass plates 2 is preferably performed in a semi-cleanroom (Class 10000 or lower), and more preferably in a cleanroom (Class 1000 or lower). If the bonding is performed outside of a cleanroom, foreign matter may be trapped between the two main surfaces 2a of the two sample glass plates 2, and the condition of the main surfaces 2a may change during the storage process.

[0034] If necessary, one main surface 2a of the sample glass plate 2 may be cleaned before bonding. For example, cleaning of the main surface 2a can be performed by scrubbing with an alkaline detergent and plasma cleaning. This ensures that one main surface 2a of the sample glass plate 2 is as clean as possible before bonding.

[0035] Herein, as a modification of this embodiment, the two main surfaces 2a of the two sample glass plates 2 may be bonded together by a method other than utilizing siloxane bonds. That is, the two main surfaces 2a may be bonded together by a method other than utilizing siloxane bonds, as long as it prevents problems such as foreign matter (source of dirt) entering between the opposing main surfaces 2a of the two integrated sample glass plates 2.

[0036] In the storage process, as shown in Figure 3, a laminate 3 consisting of two integrated sample glass plates 2 is placed on a pallet 4. Although the structure of the pallet 4 is not limited, in this embodiment an L-shaped pallet 4 is used. The pallet 4 has multiple grooves (not shown) that can hold the ends of the laminate 3. As a result, multiple laminates 3 are placed on the pallet 4 in an arranged state. The sample glass plates 2 are stored in this state for a predetermined storage period (from the completion of the sampling process to the start of the inspection process).

[0037] The inspection process involves performing an inspection using one main surface 2a of the sample glass plate 2. In this embodiment, as described above, the inspection is performed to measure the thermal shrinkage rate of the sample glass plate 2.

[0038] In the inspection process, first, as preparation for inspection, the two integrated sample glass plates 2 are separated from each other. This exposes one main surface 2a of each sample glass plate 2 again. Furthermore, the presence of an orientation flat on the sample glass plates 2 improves the efficiency of the separation process.

[0039] Here, as a modification of this embodiment, one of the sample glass plates 2 may be smaller in size, or two sample glass plates 2 of approximately the same size may be bonded together with a slight offset. By offsetting the position of the edges between the two main surfaces 2a, the work efficiency when separating the two sample glass plates 2 can be improved without providing an orientation flat.

[0040] Alternatively, multiple sample glass plates 2 may be bonded together to one main surface 2a of a single sample glass plate 2.

[0041] Next, a line 5 for inspecting the thermal shrinkage rate is drawn on one main surface 2a of the exposed sample glass plate 2, as shown in Figures 4a to 4e (Figures 4a to 4e are enlarged views of the area around line 5 on the sample glass plate 2). Line 5 is drawn, for example, by applying ink to one main surface 2a. In this embodiment, line 5 is a reference mark for measuring the thermal shrinkage rate and extends in a straight line. In addition to line 5 as in this embodiment, other marks (such as a mark formed by two intersecting lines) may also be drawn as a reference mark.

[0042] Once the drawing of line 5 is complete, the next step is to perform an inspection to measure the thermal shrinkage rate of sample glass plate 2. Since the specific methods and procedures for measuring the thermal shrinkage rate are already publicly known, a detailed explanation will be omitted.

[0043] Here, Figures 4a to 4e show, as an example, how lines 5 were drawn on five sample glass plates 2 with different storage periods (from the completion of the sampling process to the start of the inspection process). The sample glass plates 2 shown in Figures 4a to 4e had storage periods of 0 days (0.5 hours), 1 day, 9 days, 16 days, and 45 days, respectively. As can be seen, despite the significant difference in storage periods, clear lines 5 were drawn on all of the sample glass plates 2. This is because the storage process described above preserved the state of one main surface 2a of the sample glass plate 2 during the storage period, preventing new dirt from adhering to the main surface 2a. As a result, in this example, accurate inspection of the thermal shrinkage rate can be performed regardless of the length of the storage period.

[0044] For comparison with the above example, we show the case where the main surfaces 2a of the sample glass plates 2 were not bonded together during the storage period. Figures 5a to 5e show, as a comparative example, how lines 5 were drawn on five sample glass plates 2 (without bonding of the main surfaces 2a) with different storage periods. The sample glass plates 2 shown in Figures 5a to 5e were stored for 0 days (0.5 hours), 1 day, 9 days, 16 days, and 45 days, respectively. As shown in Figure 6, these sample glass plates 2 were placed on a pallet 4 with gaps between them during the storage period. As shown in Figures 5a to 5e, it can be seen that the lines 5 drawn on the sample glass plates 2 become less clear as the storage period increases. This is because the main surface 2a of the sample glass plate 2 is exposed during the storage period, and it is not possible to prevent new dirt from adhering to the main surface 2a.

[0045] <Second Embodiment> The following describes a method for manufacturing a glass plate according to the second embodiment. Note that only the differences between the second embodiment and the first embodiment described above will be explained.

[0046] The difference between the second embodiment and the first embodiment is that the inspection process involves inspecting the sample glass plate 2 for contamination, and analyzes the dirt adhering to one main surface 2a of the sample glass plate 2. Here, "dirt adhering to one main surface 2a" refers to the dirt that was adhering to one main surface 2a of the sample glass plate 2 at the time the sampling process was completed.

[0047] In the inspection process, one main surface 2a of the sample glass plate 2 is exposed, and as an example, contamination adhering to the main surface 2a is analyzed using TOF-SIMS (Time-of-Flight Secondary Ion Mass Spectrometry) with a mass spectrometer. In addition to the above analytical method, contamination may also be analyzed using FT-IR (Fourier Transform Infrared Spectroscopy) or EPMA (Electron Probe Microanalyzer). The specific analytical methods and procedures are already publicly known, so a detailed explanation will be omitted.

[0048] Here, the difference in the state of contamination of one main surface 2a between the case where the two main surfaces 2a of the sample glass plate 2 were bonded together by performing the preservation process during the above storage period (Example) and the case where the bonding was not performed (Comparative Example) is summarized in [Table 1] below. Specifically, the contact angle was used as an indicator of the state of contamination, and the change in the contact angle was compared between the Example and the Comparative Example while changing the length of the storage period. The measurement method for the contact angle was adopted in accordance with JIS R3257-1999.

[0049] [Table 1]

[0050] From the results in [Table 1] above, it can be seen that in the examples, despite the significant difference in storage period, there is almost no difference in the size of the contact angle. In other words, in the examples, regardless of the length of the storage period, there is no difference in the state of contamination of the main surface 2a between the time the sample glass plate 2 was taken and the time when the contamination was actually analyzed after the storage period. As a result, in the examples, regardless of the length of the storage period, the contamination adhering to the main surface 2a of the sample glass plate 2 at the time the sampling process is completed can be accurately analyzed. On the other hand, in the comparative example, it can be seen that the contact angle gradually increases as the storage period lengthens. This is because the main surface 2a of the sample glass plate 2 is exposed during the storage period, and it is not possible to prevent the adhesion of new contamination to the main surface 2a.

[0051] Herein, the following modifications can also be applied to the first and second embodiments described above. In the first and second embodiments described above, in the storage step, two sample glass plates 2 are made into a pair and one main surface 2a of the two sample glass plates 2 are bonded together. However, one sample glass plate 2 may be cut into two pieces, and the one main surface 2a of the cut sample glass plates 2 may be bonded together. In this case, the number of glass plates 1 taken as sample glass plates 2 in the sampling step may be an odd number or an even number.

[0052] Furthermore, as a modification of the first embodiment described above (a form in which the thermal shrinkage rate is measured by the inspection process), in the storage process, one main surface 2a of the sample glass plate 2 and the mating surface of a protective glass plate prepared separately from the sample glass plate 2 may be bonded together. The mating surface of the protective glass plate is one of the front and back surfaces of the protective glass plate. It is preferable that the mating surface is cleaner than the one main surface 2a of the sample glass plate 2, and that the mating surface has fewer particles than the one main surface 2a. The number of particles on the protective glass plate can be measured in the same way as the sample glass plate 2, for example, using a surface particle measuring instrument (GI 3200) manufactured by Hitachi High-Technologies Corporation.

[0053] Furthermore, in the first and second embodiments described above, the sample glass plate 2 was taken from a glass plate manufacturing line, but the sample glass plate 2 may be taken from a source other than a glass plate manufacturing line. For example, the sample glass plate 2 may be taken from a manufacturing line for producing electronic devices that use glass plates as components, and then the storage and inspection processes may be carried out. [Explanation of Symbols]

[0054] 1 glass plate 2 Sample glass plates 2a One principal surface 3. Laminate 4 pallets 5 lines

Claims

1. A method for manufacturing a glass plate, comprising a sampling step of taking a sample glass plate from a glass plate manufacturing line, and an inspection step of performing an inspection using one main surface of the sample glass plate, A method for manufacturing a glass plate, characterized by providing a preservation step between the sampling step and the inspection step, in which the state of one main surface is preserved by bonding the two main surfaces of the sampled glass plates together, or by bonding the one main surface of the sampled glass plate to the mating surface of a prepared protective glass plate.

2. The method for manufacturing a glass plate according to claim 1, characterized in that, in the storage step, when bonding the sample glass plates together, the sample glass plates are pressurized with a pressure of 0.5 Pa or more and 1.0 Pa or less.

3. The method for manufacturing a glass plate according to claim 1 or 2, characterized in that the surface roughness Ra of the one main surface is 0.35 nm or less.

4. The method for manufacturing a glass plate according to claim 1 or 2, characterized in that the laminated sample glass plates are placed on a pallet in the storage step.

5. The inspection step is a step of inspecting the thermal shrinkage rate of the sample glass plate, The method for manufacturing a glass plate according to claim 1 or 2, characterized in that the inspection step involves drawing a line for inspecting the thermal shrinkage rate on the main surface.

6. In the aforementioned preservation step, the state of the one main surface is preserved by bonding the two main surfaces of the collected sample glass plates together. The inspection step is a step of inspecting the sample glass plate for contamination, The method for manufacturing a glass plate according to claim 1 or 2, characterized in that the inspection step involves analyzing the dirt adhering to the one main surface.

7. A method for inspecting glass plates, comprising: a preservation step of preserving the state of one main surface by bonding one main surface of a sample glass plate to another, or by bonding one main surface of a sample glass plate to the mating surface of a protective glass plate; and an inspection step of performing an inspection using the one main surface of the sample glass plate after the preservation step.

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