Method for manufacturing a glass film

Abstract

A manufacturing method of a glass film, comprising the following steps: using a forming area (ZN1) for forming a glass ribbon (5) by means of a forming body (3), an annealing area (ZN2) for annealing while guiding the glass ribbon (5) downward, and a cooling area (ZN3) for cooling while pulling the glass ribbon (5) downward, obtaining the glass ribbon (5) that has passed through the cooling area (ZN3) as a strip-shaped glass film (2), in the cooling area (ZN3), a wrinkle-removing roller (12) for eliminating wrinkles generated in the glass ribbon (5) is in contact with the glass ribbon (5), the feeding direction of the wrinkle-removing roller (12) is inclined outward in the width direction of the glass ribbon (5) with respect to the conveying direction of the glass ribbon (5), and the peripheral speed (V2) of the wrinkle-removing roller (12) is higher than the conveying speed (V1) of the glass ribbon.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a glass film. Background Art

[0002] In recent years, mobile terminals such as smart phones and tablet PCs that have rapidly spread require thinness and light weight. Therefore, at present, there is a higher demand for thinning of glass substrates, which are constituent parts of the terminals. In order to meet this demand, it has been developed to manufacture a glass film as a thinned (for example, with a thickness of 250 μm or less) glass substrate in the form of a film.

[0003] Generally, in the manufacturing process of a glass film, there is a process of obtaining a ribbon-shaped glass film that becomes the raw material of the glass film. For example, Patent Document 1 discloses a method of obtaining a ribbon-shaped glass film by using an overflow down-draw method, which is a kind of down-draw method. In this method, the glass ribbon formed in the forming zone is sequentially passed through the annealing zone and the cooling zone, and the passed glass ribbon is obtained as a ribbon-shaped glass film.

[0004] If this method is described in detail, first, in the forming zone, a glass ribbon is continuously formed from molten glass using a forming body having a wedge-shaped cross-sectional shape. The glass ribbon just after being formed is suppressed from shrinking in the width direction by using edge rollers (cooling rollers) arranged directly below the forming body. Next, in the annealing zone, the glass ribbon descending from the forming zone is annealed to a temperature below the strain point while being guided downward by annealing rollers arranged in multiple upper and lower stages. Finally, in the cooling zone, the glass ribbon that has passed through the annealing zone is cooled while being pulled downward by support rollers. Through this process, the glass ribbon that has passed through the cooling zone is obtained as a ribbon-shaped glass film.

[0005] Prior Art Documents

[0006] Patent Documents

[0007] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2018-62430 Summary of the Invention

[0008] Problems to be Solved by the Invention

[0009] In the above method, since the thickness of the glass ribbon is extremely thin and it has flexibility, there is a problem that the glass ribbon is likely to be wrinkled during handling. Due to this wrinkle, there is a case where the obtained ribbon-shaped glass film is broken when the conveying direction of the ribbon-shaped glass film is changed or the ribbon-shaped glass film is cut in the width direction.

[0010] In view of the above situation, the technical problem to be solved is to eliminate the wrinkles generated in the glass ribbon when the glass ribbon formed in the forming zone is sequentially passed through the annealing zone and the cooling zone and the passed glass ribbon is obtained as a ribbon-shaped glass film.

[0011] Solution to the problem

[0012] The method for manufacturing a glass film for solving the above problem includes the following steps: a forming area where a glass ribbon is formed from molten glass using a forming body for the down-draw method, an annealing area where the glass ribbon descending from the forming area is guided downward while annealing is performed, and a cooling area where the glass ribbon that has passed through the annealing area is pulled downward by a support roller while cooling is performed, and the glass ribbon that has passed through the cooling area is obtained as a strip-shaped glass film. The method for manufacturing the glass film is characterized in that, in the cooling area, a wrinkle-removing roller for eliminating wrinkles generated in the glass ribbon contacts the glass ribbon, the feeding direction of the wrinkle-removing roller is inclined outward in the width direction of the glass ribbon with respect to the conveying direction of the glass ribbon, and the peripheral speed of the wrinkle-removing roller is higher than the conveying speed of the glass ribbon.

[0013] In this method, regarding the wrinkle-removing roller that contacts the glass ribbon in the cooling area, its feeding direction is inclined outward in the width direction of the glass ribbon with respect to the conveying direction of the glass ribbon, and its peripheral speed is higher than the conveying speed of the glass ribbon. Along with the contact with this wrinkle-removing roller, a pulling force in the width direction can be effectively applied to the glass ribbon, so that the wrinkles generated in the glass ribbon can be eliminated using this pulling force.

[0014] In the above method, preferably, in the conveying path of the glass ribbon, the wrinkle-removing roller is arranged at a position upstream of the support roller.

[0015] In this way, the wrinkles generated in the glass ribbon can be eliminated at a position upstream of the support roller in the conveying path of the glass ribbon. Therefore, the risk that the glass ribbon breaks due to the wrinkles reaching the support roller (the wrinkles are clamped by the support roller from both the front and back sides) can be appropriately eliminated.

[0016] In the above method, preferably, as the wrinkle-removing roller, a roller having a softness that can be deformed along with the contact with the glass ribbon on its peripheral portion is used, and a pair of wrinkle-removing rollers sandwich the glass ribbon in the thickness direction and contact it from both the front and back sides.

[0017] In this way, since the peripheral portion of the wrinkle-removing roller has softness, the risk that the glass ribbon breaks due to the contact with the wrinkle-removing roller can be appropriately eliminated. Moreover, since a pair of wrinkle-removing rollers sandwich the glass ribbon in the thickness direction, although the peripheral portion of the wrinkle-removing roller has softness, a pulling force in the width direction can be reliably applied to the glass ribbon.

[0018] In the above method, preferably, as the wrinkle-removing roller, a brush roller having bristles on its peripheral portion is used.

[0019] In this way, the bristles provided on the circumferential portion of the brush roll are flexed and deformed as they come into contact with the glass ribbon. As a result, an excessive load that would cause breakage is not applied to the glass ribbon, and a pulling force in the width direction can be applied.

[0020] In the above method, it is preferable that the circumferential portion of the wrinkle-removing roll slides relative to the glass ribbon.

[0021] In this way, the surface of the glass ribbon slides against the circumferential portion of the wrinkle-removing roll, which is advantageous in preventing an excessive load from being applied to the glass ribbon when preventing a pulling force in the width direction from acting on the glass ribbon.

[0022] In the above method, it is preferable that the feeding direction of the support roll is the same direction as the conveying direction of the glass ribbon.

[0023] In this way, since the feeding direction of the support roll that pulls the glass ribbon is the same direction as the conveying direction of the glass ribbon, the risk that the glass ribbon is displaced in the width direction due to the inclination of the feeding direction of the wrinkle-removing roll relative to the conveying direction of the glass ribbon can be appropriately eliminated.

[0024] In the above method, it is preferable that, as the support roll, a roll is used that includes a first roll that comes into contact with one end portion in the width direction of the glass ribbon and a second roll that is connected to the first roll via a shaft and comes into contact with the other end portion in the width direction of the glass ribbon.

[0025] In this way, the feeding directions of the first roll and the second roll reliably become the same direction as the conveying direction of the glass ribbon, and thus the effect of eliminating the above-mentioned displacement of the glass ribbon can be obtained more effectively.

[0026] In the above method, it is preferable that the glass ribbon has an effective portion that exists at the center in the width direction of the glass ribbon and non-effective portions that sandwich the effective portion and exist at both ends in the width direction, and the wrinkle-removing roll is brought into contact with the non-effective portions of the glass ribbon.

[0027] In this way, since the wrinkle-removing roll comes into contact with the non-effective portions of the glass ribbon, it is possible to prevent the effective portion from being damaged or contaminated by the wrinkle-removing roll. In addition, the width direction ends of the glass ribbon are pulled by the wrinkle-removing roll, so that the region where the pulling force acts on the glass ribbon can be widened as much as possible, which is more advantageous in eliminating wrinkles.

[0028] Advantages of the Invention

[0029] According to the method for manufacturing a glass film of the present invention, it is possible to eliminate wrinkles generated in a glass ribbon when the glass ribbon formed in a forming region is sequentially passed through an annealing region and a cooling region and the passed glass ribbon is taken as a strip-shaped glass film. Description of the Drawings

[0030] Figure 1 This is a cross-sectional view showing a method for manufacturing a glass film.

[0031] Figure 2 This is a cross-sectional view showing a method for manufacturing a glass film.

[0032] Figure 3a This is a front view showing a brush roll.

[0033] Figure 3b This is a side view showing a brush roll. Detailed implementation mode

[0034] Hereinafter, a method for manufacturing a glass film according to an embodiment will be described with reference to the accompanying drawings. It should be noted that the X direction, Y direction, and Z direction shown in the respective drawings referred to in the description of the embodiment are orthogonal directions.

[0035] This manufacturing method includes using Figure 1 and Figure 2 shown manufacturing apparatus 1 to obtain a strip-shaped glass film 2 that is a raw material for the glass film. This process includes a forming process P1 performed in the forming zone ZN1, an annealing process P2 performed in the annealing zone ZN2, a cooling process P3 performed in the cooling zone ZN3, and a wrinkle removal process P4.

[0036] The forming process P1 is a process of continuously forming a glass ribbon 5 from molten glass 4 using a forming body 3 (here, for overflow down-draw method). The forming body 3 is housed in a forming furnace 6, and a heating device (such as a plate heater) (not shown) for heating the forming body 3 is provided in the forming furnace 6.

[0037] The forming body 3 has: a groove 3a for allowing the molten glass 4 to flow in; a pair of side faces 3b, 3b for allowing the molten glass 4 that overflows from the groove 3a to both sides to flow down respectively; and a lower end portion 3c for fusing (confluencing) the molten glass 4 flowing along each side face 3b. The glass ribbon 5 is continuously formed from the molten glass 4 fused at the lower end portion 3c.

[0038] The glass ribbon 5 has an effective portion 5a existing at the center in its width direction (X direction) and non-effective portions 5b sandwiching the effective portion 5a and existing at both ends in the width direction respectively. The effective portion 5a is a portion that includes the part that will become the product glass film later, and the non-effective portion 5b is a portion that will not become the product and will be discarded later. Ears having a thicker wall than other portions are formed at the portions corresponding to the width direction edges (edges) of the non-effective portions 5b at the width direction ends of the glass ribbon 5.

[0039] The glass ribbon 5 immediately after forming is restrained from shrinking in the width direction by using an edge roll 7 (cooling roll) disposed directly below the forming body 3.

[0040] A pair of edge rollers 7 are arranged to sandwich the glass ribbon 5 in the thickness direction (Z direction). Each of the pair of edge rollers 7, 7 includes a shaft 7a extending in the width direction of the glass ribbon 5 and a first roller 7b and a second roller 7c connected to each other via the shaft 7a. The two rollers 7b, 7c are made of a heat-resistant material and are both in contact with the non-effective portion 5b of the glass ribbon 5. By sandwiching the glass ribbon 5 in the thickness direction between the first rollers 7b, 7b and the second rollers 7c, 7c of the pair of edge rollers 7, 7, the shrinkage of the glass ribbon 5 in the width direction is suppressed while feeding it downward.

[0041] The annealing process P2 is a process of annealing the glass ribbon 5 descending from the forming zone ZN1 to a temperature below the strain point while guiding it downward. An annealing furnace 8 and annealing rollers 9 arranged in multiple upper and lower stages (five upper and lower stages in the illustrated example) are used in the execution of the annealing process P2.

[0042] The annealing furnace 8 is arranged below the forming furnace 6. A heating device (such as a plate heater), not shown, for adjusting the ambient temperature inside the annealing furnace 8 is provided in the annealing furnace 8.

[0043] In each of the multiple upper and lower stages, a pair of annealing rollers 9 are arranged to sandwich the glass ribbon 5 in the thickness direction. Each of the pair of annealing rollers 9, 9 includes a shaft 9a extending in the width direction of the glass ribbon 5 and a first roller 9b and a second roller 9c connected to each other via the shaft 9a. The two rollers 9b, 9c are made of ceramics as an example and are both capable of contacting the non-effective portion 5b of the glass ribbon 5. The glass ribbon 5 is guided downward by the first rollers 9b, 9b and the second rollers 9c, 9c of the pair of annealing rollers 9, 9.

[0044] Here, as long as the first rollers 9b, 9b and the second rollers 9c, 9c sandwich the glass ribbon 5 in the thickness direction, there is also a case where they do not sandwich but only restrict the oscillation of the glass ribbon 5 along the thickness direction.

[0045] The cooling process P3 is a process of cooling the glass ribbon 5 that has passed through the annealing zone ZN2 while pulling it downward by the support rollers 10. The support rollers 10 are arranged in a cooling chamber 11 arranged below the annealing furnace 8.

[0046] A pair of supporting rollers 10 are arranged sandwiching the glass ribbon 5 in the thickness direction. Each of the pair of supporting rollers 10, 10 includes a shaft 10a extending in the width direction of the glass ribbon 5 and a first roller 10b and a second roller 10c connected to each other via the shaft 10a. The two rollers 10b, 10c are made of rubber as an example and can both contact the non-effective portion 5b of the glass ribbon 5. The first rollers 10b, 10b of the pair of supporting rollers 10, 10 and the second rollers 10c, 10c sandwich and pull the glass ribbon 5 in the thickness direction, thereby determining the conveying speed V1 (drawing speed) of the glass ribbon 5. The glass ribbon 5 that has passed through the cooling zone ZN3 during conveyance is obtained as the strip glass film 2.

[0047] The wrinkle-removing process P4 is a process for eliminating wrinkles generated in the glass ribbon 5. In the wrinkle-removing process P4, the wrinkle-removing roller 12 is brought into contact with the glass ribbon 5, and a pulling force in the width direction is applied to the glass ribbon 5 accordingly to eliminate the wrinkles.

[0048] Here, the thinner the thickness of the glass ribbon 5, the easier it is for wrinkles to be generated in the glass ribbon 5. Therefore, this manufacturing method is preferably applied to the case where the thickness of the glass ribbon 5 (the thickness of the effective portion 5a) is 250 μm or less, more preferably applied to the case where it is 100 μm or less, and most preferably applied to the case where it is 70 μm or less. On the other hand, in order to stably manufacture the glass ribbon 5, the thickness of the glass ribbon 5 is preferably 10 μm or more.

[0049] The wrinkle-removing roller 12 is arranged in the conveying path of the glass ribbon 5 at a position downstream of the annealing roller 9 and upstream of the supporting roller 10. Moreover, the wrinkle-removing roller 12 is arranged on both the one end side and the other end side in the width direction of the glass ribbon 5 in a symmetric configuration with the center line in the width direction of the glass ribbon 5 as the reference. In each of the one end side and the other end side, the wrinkle-removing roller 12 is paired sandwiching the glass ribbon 5 in the thickness direction, and the pair of wrinkle-removing rollers 12, 12 contact the non-effective portion 5b of the glass ribbon 5 from both the front and back sides. Specifically, the wrinkle-removing roller 12 contacts a portion of the non-effective portion 5b that is closer to the inner side in the width direction than the ear portion. It should be noted that the wrinkle-removing roller 12 can move axially as shown by the two end arrows in Figure 1 Thus, regarding the arrangement of the wrinkle-removing roller 12 (the arrangement of the roller portion), it can be changed to a position closer to the inner side, closer to the outer side, and the same position in the width direction as the first roller 10b and the second roller 10c of the supporting roller 10.

[0050] The axis of the wrinkle removing roller 12 is inclined with respect to the width direction (horizontal direction) of the glass ribbon 5. Thus, the feeding direction of the wrinkle removing roller 12 is inclined outward in the width direction of the glass ribbon 5 with respect to the conveying direction (Y direction) of the glass ribbon 5. On the other hand, the feeding direction of the supporting roller 10 arranged in the cooling zone ZN3 in the same manner as the wrinkle removing roller 12 becomes the same direction as the conveying direction of the glass ribbon 5. Here, the inclination of the feeding direction of the wrinkle removing roller 12 with respect to the conveying direction of the glass ribbon 5 (the inclination when looking down at the glass ribbon 5) is preferably 10° or less, more preferably 5° or less, in order to prevent excessive pulling force from acting on the glass ribbon 5. On the other hand, the inclination of the feeding direction of the wrinkle removing roller 12 with respect to the conveying direction of the glass ribbon 5 is preferably 1° or more in order to maintain good wrinkle removing performance.

[0051] The wrinkle removing roller 12 is a driving roller connected to a driving source (such as a motor) not shown. The peripheral speed V2 of the wrinkle removing roller 12 is higher than the conveying speed V1 of the glass ribbon 5. Here, the peripheral speed V2 of the wrinkle removing roller 12 is preferably 1.01 to 1.5 times, more preferably 1.05 to 1.3 times, the speed of the conveying speed V1 of the glass ribbon 5 in order to effectively eliminate the wrinkles generated in the glass ribbon 5.

[0052] As Figure 3a and Figure 3b shown, as the wrinkle removing roller 12, a brush roller 13 whose roller part is formed by a brush is used. The peripheral part of the brush roller 13 is composed of a plurality of tufts 13a arranged along the circumferential direction, and each tuft 13a includes a plurality of bristles 13aa. The tuft 13a (bristles 13aa) has flexibility and can be flexibly deformed along with the contact with the glass ribbon 5. Thus, when the brush roller 13 contacts the glass ribbon 5, the tuft 13a (bristles 13aa) slides relative to the surface of the glass ribbon 5 while being flexibly deformed. It should be noted that only the tuft 13a (bristles 13aa) in the whole brush roller 13 contacts the surface of the glass ribbon 5.

[0053] Here, the peripheral part of the wrinkle removing roller 12 (brush roller 13) is preferably made of a material having heat resistance such that the melting point is 180°C or higher. In the present embodiment, hair made of 66 nylon with a melting point of 265°C is used as the bristles 13aa.

[0054] A cutting process for cutting the strip-shaped glass film 2 in the width direction, a conversion process for converting the conveying direction of the strip-shaped glass film 2 from the up-and-down direction to the horizontal direction, etc. are performed on the strip-shaped glass film 2 obtained through the cooling process P3 and the wrinkle removing process P4. After that, by performing various processes (cleaning process, inspection process, etc.), a product glass film is manufactured from the strip-shaped glass film 2.

[0055] In the method for manufacturing the glass film described above, regarding the wrinkle-removing roller 12 that contacts the glass ribbon 5 in the cooling zone ZN3, its feeding direction is inclined outward in the width direction of the glass ribbon 5 with respect to the conveying direction of the glass ribbon 5, and its peripheral speed V2 is higher than the conveying speed V1 of the glass ribbon 5. Thus, a pulling force in the width direction can be effectively applied to the glass ribbon 5 along with the contact with the wrinkle-removing roller 12, and the wrinkles generated in the glass ribbon 5 can be eliminated using this pulling force.

[0056] Here, the following modification examples can be applied to the above-described embodiment. In the above-described embodiment, in the cooling zone ZN3, the wrinkle-removing roller 12 is disposed at a position upstream of the support roller 10 in the conveying path of the glass ribbon 5, but it is not necessarily limited to this, and the wrinkle-removing roller 12 can also be disposed at a position downstream of the support roller 10.

[0057] In addition, in the above-described embodiment, the bristles 13aa provided on the circumferential portion of the brush roller 13 are made of 66 nylon, but of course, it is not limited to this, and they can also be made of materials other than 66 nylon (such as polyphenylene sulfide, meta-aramid fiber, etc.). Moreover, as the wrinkle-removing roller 12, it is not limited to the brush roller 13, and a roller having flexibility in its circumferential portion that can deform along with the contact with the glass ribbon 5 can be used. Therefore, for example, a roller whose circumferential portion is made of resin, rubber, glass fiber cloth, carbon fiber cloth, sponge, etc. can also be used as the wrinkle-removing roller 12.

[0058] In addition, in the above-described embodiment, only one stage of the pair of wrinkle-removing rollers 12, 12 is used, but it is not limited to this method, and multiple stages of the pair of wrinkle-removing rollers 12, 12 can also be arranged vertically.

[0059] In addition, in the above-described embodiment, as the edge roller 7, the first roller 7b and the second roller 7c are installed on one shaft 7a, but it is not limited to this method, and the first roller 7b and the second roller 7c can also be separately provided with shafts 7a.

[0060] In addition, in the above-described embodiment, as the annealing roller 9, the first roller 9b and the second roller 9c are installed on one shaft 9a, but it is not limited to this method, and the first roller 9b and the second roller 9c can also be separately provided with shafts 9a.

[0061] In addition, in the above-described embodiment, as the support roller 10, the first roller 10b and the second roller 10c are installed on one shaft 10a, but it is not limited to this method, and the first roller 10b and the second roller 10c can also be separately provided with shafts 10a.

[0062] Description of Reference Numerals

[0063] 2 Strip-shaped glass film

[0064] 3 Forming body

[0065] 4 Molten glass

[0066] 5 Glass ribbon

[0067] 5a Effective part

[0068] 5b Non-effective part

[0069] 10 Support roll

[0070] 10a Shaft

[0071] 10b First roll

[0072] 10c Second roll

[0073] 12 Wrinkle-removing roll

[0074] 13 Brush roll

[0075] 13aa Bristles

[0076] V1 Conveying speed of the glass ribbon

[0077] V2 Peripheral speed of the wrinkle-removing roll

[0078] ZN1 Forming zone

[0079] ZN2 Annealing zone

[0080] ZN3 Cooling zone.

Claims

1. A method for manufacturing a glass film, comprising the following steps: a forming zone for forming a glass ribbon from molten glass using a forming body for the down-draw method, an annealing zone for annealing while guiding the glass ribbon descending from the forming zone downward, and a cooling zone for cooling while pulling the glass ribbon that has passed through the annealing zone downward by a support roller, and obtaining the glass ribbon that has passed through the cooling zone as a strip-shaped glass film. The method for manufacturing the glass film is characterized in that in the cooling zone, a wrinkle-removing roller for eliminating wrinkles generated in the glass ribbon contacts the glass ribbon. The feeding direction of the wrinkle-removing roller is inclined outward in the width direction of the glass ribbon with respect to the conveying direction of the glass ribbon, and the peripheral speed of the wrinkle-removing roller is higher than the conveying speed of the glass ribbon.

2. The method for manufacturing a glass film according to claim 1, characterized in that in the conveying path of the glass ribbon, the wrinkle-removing roller is arranged at a position upstream of the support roller.

3. The method for manufacturing a glass film according to claim 1 or 2, characterized in that as the wrinkle-removing roller, a roller having flexibility in its peripheral portion that can be deformed by contact with the glass ribbon is used, and a pair of the wrinkle-removing rollers sandwich the glass ribbon in the thickness direction and contact it from both the front and back sides.

4. The method for manufacturing a glass film according to claim 3, characterized in that as the wrinkle-removing roller, a brush roller having bristles in its peripheral portion is used.

5. The method for manufacturing a glass film according to claim 4, characterized in that the peripheral portion of the wrinkle-removing roller slides relative to the glass ribbon.

6. The method for manufacturing a glass film according to any one of claims 1, 2, 4, and 5, characterized in that the feeding direction of the support roller is set to the same direction as the conveying direction of the glass ribbon.

7. The method for manufacturing a glass film according to claim 6, characterized in that as the support roller, a roller having a first roller that contacts one end portion in the width direction of the glass ribbon and a second roller that is connected to the first roller via a shaft and contacts the other end portion in the width direction of the glass ribbon is used.

8. The method for manufacturing a glass film according to any one of claims 1, 2, 4, 5, and 7, characterized in that the glass ribbon has an effective portion existing at the center in the width direction of the glass ribbon and non-effective portions sandwiching the effective portion and existing at both ends in the width direction respectively, and the wrinkle-removing roller contacts the non-effective portions of the glass ribbon.

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