TWI881081B - Method for manufacturing glass plate - Google Patents

Abstract

The cleaning step S2 of the glass plate manufacturing method includes: a first cleaning step S21, supplying a first cleaning liquid CS1 to the glass plate G and cleaning the glass plate G; and a second cleaning step S23, after the first cleaning step S21, supplying a second cleaning liquid CS2 to the glass plate G and cleaning the glass plate G. The first cleaning liquid CS1 is an acidic cleaning liquid, and the second cleaning liquid CS2 is an alkaline cleaning liquid.

Description

Method for manufacturing glass plate

The present invention relates to a method for manufacturing a glass sheet.

In recent years, panel displays such as liquid crystal displays and organic EL (electroluminescent) displays have been continuously advanced in precision. Along with this, a sophisticated electrical circuit is formed on a glass plate used as a substrate for the display using the manufacturing steps of the display. Therefore, such a glass plate is required to be highly clean without dust or dirt.

The manufacturing steps of the glass plate include: an unbundling step of taking out the glass original plate stored on a pallet, for example; a cutting step of cutting the taken out glass original plate into glass plates of a specified size; an end surface processing step of applying end surface processing to the glass plate; and a cleaning step of cleaning the end surface processed glass plate. As a method for cleaning the glass plate, a method of cleaning the glass plate conveyed in a specified direction by a cleaning tool such as a cleaning plate or a cleaning brush (for example, refer to Patent Document 1) can be cited.

[Prior art literature] [Patent Literature]

[Patent document 1] Japanese Patent Publication No. 2017-14060

The glass original plate supplied to the manufacturing step of the glass plate is loaded on a pallet for storage, and on the pallet, a plurality of glass original plates are stacked via resin sheets.

In this case, if it is stored on the pallet for a long time, calcium dirt or dirt containing organic matter may be generated. In addition, these dirts are firmly attached to the original glass plate and are sometimes difficult to remove from the glass plate during the cleaning step.

Therefore, the technical problem of the present invention is to improve the cleaning power in the cleaning step of the glass plate.

The present invention is a method for manufacturing a glass plate for solving the above-mentioned problem, comprising: a storage step, storing the glass plate in contact with the resin sheet; a cleaning step, cleaning the glass plate after the storage step; the method for manufacturing the glass plate is characterized in that: the cleaning step comprises: a first cleaning step, supplying a first cleaning liquid to the glass plate and cleaning the glass plate; and a second cleaning step, supplying a second cleaning liquid to the glass plate and cleaning the glass plate after the first cleaning step; the first cleaning liquid is an acidic cleaning liquid, and the second cleaning liquid is an alkaline cleaning liquid.

According to the active research of the inventors, it has been confirmed that when a glass plate is stored for a long period of time in contact with a resin sheet, the dirt transferred from the resin sheet to the surface of the glass plate contains calcium (hereinafter referred to as "calcium dirt"), and it is difficult to remove the calcium dirt from the glass plate by cleaning compared to other dirt.

The inventors of the present invention have found that after performing a first cleaning step in which the first cleaning liquid is set to an acidic cleaning liquid, performing a second cleaning step in which the second cleaning liquid is set to an alkaline cleaning liquid can effectively remove calcium dirt and dirt containing organic matter from the glass plate.

The acid cleaning solution may contain a hydroxy acid. Examples of hydroxy acids (oxyacids) include glycolic acid, lactic acid, tartaric acid, citric acid, apple acid, and salicylic acid. Hydroxy acid is a carboxylic acid that also has a hydroxyl group and is highly water-soluble. In addition, the carboxyl group contained in the molecule of the hydroxy acid reacts with the calcium ion (Ca ²⁺ ) of the calcium dirt on the surface of the glass plate through a chelate effect, extracting the calcium ion within one molecule or through a plurality of molecules and stabilizing it, thereby being effective in removing the calcium component fixed to the surface of the glass plate.

The alkaline cleaning solution may contain a hydroxide salt, for example, at least one of sodium hydroxide and potassium hydroxide.

In the first cleaning step, the glass plate can be cleaned by bringing the cleaning tool into contact with the glass plate. In this way, the first cleaning step can be performed efficiently.

In the second cleaning step, the glass plate can be cleaned by bringing the cleaning tool into contact with the glass plate. In this way, the second cleaning step can be performed efficiently.

The method may include a liquid removal step of removing the first cleaning liquid attached to the glass plate by supplying a removal liquid to the glass plate after the first cleaning step and before the second cleaning step, wherein the removal liquid is warm water. The first cleaning liquid attached to the glass plate after the first cleaning step is removed by the liquid removal step, and the glass plate can be cleaned more effectively by the second cleaning liquid in the subsequent second cleaning step.

This method may include a rinsing step of removing the second cleaning liquid attached to the glass plate by supplying a rinsing liquid to the glass plate after the second cleaning step, wherein the rinsing liquid contains alkaline electrolyzed water. By covering the surface of the glass plate with anions in the rinsing step, it is possible to prevent the particulate matter dispersed in the rinsing liquid from being attached to the surface of the glass plate, thereby improving the cleanliness of the surface of the glass plate after the rinsing step.

According to the present invention, the cleaning power in the cleaning step of the glass plate can be improved.

1: Cleaning device

2: First cleaning section

2a: Upper cleaning machine, cleaning machine

2b: Lower side cleaning machine, cleaning machine

3: Liquid removal section

3a: Upper side air knife, air knife

3b: Lower side air knife, air knife

4: Second cleaning section

4a: Upper cleaning machine

4b: Lower side cleaning machine

5: Rinsing section

5a: Upper flushing liquid supply part, flushing liquid supply part

5b: Lower side flushing liquid supply part, flushing liquid supply part

6: Drying section

6a: Upper side air knife, air knife

6b: Lower side air knife, air knife

7: Transport device

7a: Transport roller

8a: Upper cleaning tools, cleaning tools

8b: Lower side cleaning tools, cleaning tools

9a: The main body of the upper cleaning tool

9b: The main body of the lower cleaning tool

10: Cleaning components

11: Shaft

12: Supply hole

13: Storage slot

14: Bearing part

15a: Upper cleaning tools, cleaning tools

15b: Lower side cleaning tools, cleaning tools

16a: The main body of the upper cleaning tool

16b: The main body of the lower cleaning tool

17a: Upper side removal liquid supply unit

17b: Lower side removal liquid supply unit

CS1: First cleaning solution

CS2: Second cleaning solution

G: Glass plate

Ga: first main surface, main surface

Gb: Second main surface, main surface

P: Pallet

PB: Bale body

RS: Resin sheet

S1: Storage steps

S2: Cleaning step

S21: First cleaning step

S22: Liquid removal step

S23: Second cleaning step

S24: Rinse step

S25: Drying step

SS: Storage space

X: Transport direction

FIG1 is a cross-sectional view showing a method for manufacturing a glass plate according to a first embodiment of the present invention.

Figure 2 is a cross-sectional view showing the structure of the cleaning machine in the first cleaning section and the second cleaning section.

Figure 3 is a flow chart showing the cleaning steps.

FIG4 is a cross-sectional view showing a method for manufacturing a glass plate according to a second embodiment of the present invention.

Below, the embodiments for implementing the present invention are described with reference to the drawings. Figures 1 to 3 show the first embodiment of the method for manufacturing a glass plate of the present invention.

As shown in FIG1 , the method includes: a storage step S1 for storing the glass plate G, and a cleaning step S2 for cleaning the glass plate G. The method may also include the unbundling step, the cutting step, and the end surface processing step between the storage step S1 and the cleaning step S2. The method may also include, as a subsequent step of the cleaning step S2, an inspection step of the glass plate G, and a packing step of loading the glass plate G on a pallet.

In the storage step S1, the glass plates G are managed in the state of a package body PB. The package body PB is formed by loading a plurality of glass plates G on a pallet P. In the storage step S1 of this embodiment, the glass plates G are stored in a flat position, but the glass plates G may also be stored in a tilted position.

The glass sheet G is formed by cutting a long glass ribbon formed by, for example, an overflow down draw method. In the overflow down draw method, molten glass flows into an overflow groove provided at the upper portion of a forming body having a substantially wedge-shaped cross section, and the molten glass overflowing from the overflow groove flows down along the side walls of the forming body and is fused and integrated at the lower end of the forming body, thereby continuously forming the glass ribbon. The glass sheet G is not limited to the overflow down draw method, and can also be manufactured by various other forming methods such as the float method.

The glass plate G is formed into a rectangular shape, but is not limited to the above shape. The glass plate G includes a first main surface Ga and a second main surface Gb. In this embodiment, the first main surface Ga is used as a guarantee surface, and the second main surface Gb is used as a non-guaranteed surface. Here, the so-called "guaranteed surface" means, for example, the surface on the film-forming side where a transparent conductive film is applied during the manufacturing process of the display.

The glass plate G uses, for example, silicate glass and silica glass, preferably borosilicate glass, sodium calcium glass, aluminum silicate glass, chemically strengthened glass, and alkali-free glass. Here, the so-called alkali-free glass is glass that does not substantially contain alkali components (alkali metal oxides), specifically, glass with a weight ratio of alkali components of 3000ppm or less. The weight ratio of the alkali component in the present invention is preferably 1000ppm or less, more preferably 500ppm or less, and most preferably 300ppm or less.

A resin sheet RS is stacked on each glass plate G. The resin sheet RS prevents the glass plates G from contacting each other in the package body PB.

The resin sheet RS includes a rectangular sheet having a larger surface area than the glass plate G. The resin sheet RS includes, for example, a foamed resin sheet formed of a resin having polyethylene as a main component, a resin protective film, etc. The resin sheet RS may contain an antistatic agent such as a polymer antistatic agent, or a surfactant such as an anionic surfactant or a non-ionic surfactant.

In the storage step S1, the package PB is stored for several days to one year, for example. The longer the storage period, the more dirt on the glass plate G, and the more significant the cleaning effect of the present invention. Therefore, the storage period is preferably more than two months, and more preferably more than four months. The package PB after the storage step S1 is transported out of the storage space SS.

In the cleaning step S2, the glass plate G taken out from the package body PB is supplied. In this case, the resin sheet RS is peeled off from the glass plate G. In the cleaning step S2, the glass plate G is cleaned by the cleaning device 1 shown in FIG. 1 .

The cleaning device 1 mainly includes: a first cleaning section 2, which supplies the first cleaning liquid CS1 to the glass plate G while cleaning the glass plate G; a liquid removal section 3, which removes the first cleaning liquid CS1 attached to the glass plate G; a second cleaning section 4, which supplies the second cleaning liquid CS2 to the glass plate G while cleaning the glass plate G; a rinse section 5, which supplies the rinse liquid to the glass plate G while removing the second cleaning liquid CS2 attached to the glass plate G; and a drying section 6. In addition, the cleaning device 1 also includes a conveying device 7 for conveying the glass plate G along a predetermined conveying direction X.

The first cleaning unit 2 includes: an upper cleaning machine 2a for cleaning the first main surface Ga of the glass plate G, and a lower cleaning machine 2b for cleaning the second main surface Gb of the glass plate G.

The upper cleaning machine 2a includes an upper cleaning tool 8a in contact with the first main surface Ga, and a main body 9a supporting the upper cleaning tool 8a. The lower cleaning machine 2b includes a lower cleaning tool 8b in contact with the second main surface Gb, and a main body 9b supporting the lower cleaning tool 8b. The upper cleaning machine 2a and the lower cleaning machine 2b are the same type of cleaning machines.

The following describes the structures of the cleaning machines 2a and 2b by taking the upper cleaning machine 2a shown in FIG. 2 as an example. The upper cleaning tool 8a is configured in a disc shape, but is not limited to the above shape. The upper cleaning tool 8a includes: a cleaning member 10 in contact with the first main surface Ga of the glass plate G, and a shaft 11 supporting the cleaning member 10.

The cleaning member 10 is formed into a disk shape (disk shape) by, for example, a foam resin molded body or a foam rubber molded body (foam sponge), or a felt-like fiber molded body (felt sponge). The cleaning member 10 is not limited to the above structure, and may also include a brush.

The cleaning member 10 has a supply hole 12 for supplying the first cleaning liquid CS1 to the glass plate G. The shaft 11 is configured as a tube, and the first cleaning liquid CS1 can pass through the inside. The shaft 11 is connected to the supply hole 12 of the cleaning member 10.

The main body 9a includes: a storage tank 13 for storing the first cleaning liquid CS1; a bearing portion 14 for rotatably supporting the shaft portion 11 of the first cleaning tool; and a driving portion (not shown) for rotating the shaft portion 11.

The storage tank 13 stores an acidic cleaning liquid as the first cleaning liquid CS1. The acidic cleaning liquid includes, for example, an aqueous solution containing a hydroxy acid. Examples of the hydroxy acid include glycolic acid, lactic acid, tartaric acid, citric acid, apple acid, salicylic acid, and the like. Hydroxylic acid is a carboxylic acid that also has a hydroxyl group and is highly water-soluble. In addition, the carboxyl group contained in the molecule of the hydroxyl acid reacts with the calcium ion (Ca2 ⁺ ) of the calcium stain on the surface (each main surface Ga, main surface Gb) of the glass plate G through a chelating effect, extracting the calcium ion within one molecule or through a plurality of molecules and stabilizing it, thereby being effective in removing the calcium component attached to each main surface Ga, main surface Gb of the glass plate G. For example, when glycolic acid is used as the acid cleaning solution, its concentration is preferably set to 1.5% to 10%, but is not limited to the above range. Furthermore, the acid cleaning solution may contain one or more hydroxy acids.

In addition, the first cleaning liquid CS1 may also contain a surfactant for cleaning and removing organic dirt on the glass plate G. As the surfactant, it can be selected from a group including anionic surfactants represented by alkylbenzene sulfonates, etc., or nonionic surfactants represented by polyoxyethylene alkyl ethers, etc. The surfactant has the following effects: it captures organic dirt from the dirt transferred from the resin sheet RS to the main surfaces Ga and Gb of the glass plate G and removes it from the main surfaces Ga and Gb of the glass plate G.

The acidic cleaning solution may further contain a chelating agent that preferentially replenishes calcium ions to prevent the calcium ions (Ca ²⁺ ) released in the cleaning solution from being attached to the main surfaces Ga and Gb of the glass plate G. As the added chelating agent, various organic polymer chelating agents such as sodium tripolyphosphate, ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid (NTA), sodium citrate, etc. may be used, and inorganic substances such as zeolite that selectively adsorb calcium ions may also be used.

The storage tank 13 may also include a heater for heating the first cleaning liquid CS1. In this case, the temperature of the first cleaning liquid CS1 is preferably set to 40°C~50°C, but is not limited to the above range.

The first cleaning unit 2 uses the driving unit to rotate the shaft 11 while the cleaning tools 8a and 8b are in contact with the main surfaces Ga and Gb of the glass plate G, thereby wiping and cleaning the glass plate G.

The liquid removal section 3 is used to remove the first cleaning liquid CS1 attached to the glass plate G after passing through the first cleaning section 2. The liquid removal section 3 includes an upper air knife 3a and a lower air knife 3b. The liquid removal section 3 can remove the first cleaning liquid CS1 from the glass plate G by blowing the air of each air knife 3a and air knife 3b toward each main surface Ga and main surface Gb of the glass plate G.

The second cleaning section 4 includes an upper cleaning machine 4a and a lower cleaning machine 4b that can perform wiping cleaning on the glass plate G. The upper cleaning machine 4a includes an upper cleaning tool 15a and a main body 16a that supports the upper cleaning tool 15a. The lower cleaning machine 4b includes a lower cleaning tool 15b and a main body 16b that supports the lower cleaning tool 15b. The upper cleaning machine 4a and the lower cleaning machine 4b of the second cleaning section 4 have the same structure as the upper cleaning machine 2a and the lower cleaning machine 2b in the first cleaning section 2.

However, the second cleaning section 4 is different from the first cleaning section 2 in that an alkaline cleaning liquid is used as the second cleaning liquid CS2. The alkaline cleaning liquid contains a hydroxide, for example, an aqueous solution containing at least one of sodium hydroxide and potassium hydroxide. The total concentration of sodium hydroxide and potassium hydroxide in the alkaline cleaning liquid is preferably set to 0.5%~10%, and more preferably set to 1.5%~10%. The second cleaning liquid CS2 may also contain a surfactant or a chelating agent. In addition, the temperature of the second cleaning liquid CS2 is preferably set to 40℃~50℃, but is not limited to the above range.

Alkaline cleaning liquids are not limited to those containing hydroxides, but may also contain carbonates. As carbonates, sodium carbonate, potassium carbonate, sodium sesquicarbonate, sodium bicarbonate (sodium bicarbonate), etc. may be used. Moreover, the alkaline cleaning liquids are not limited to the above contents, and may also contain alkaline builder aids such as silicates.

The alkaline cleaning liquid can more effectively remove other dirt containing organic matter from the glass plate G. In addition, by alkalizing the main surfaces Ga and Gb of the glass plate G to maintain a negative charge, the highly polar surfactant components adsorbed and remaining on the main surfaces Ga and Gb of the glass plate G after using the first cleaning liquid CS1 (acidic cleaning agent) can be particularly effectively removed.

The alkaline cleaning solution may also contain a surfactant component for effectively removing organic dirt or residues of the acidic cleaning agent on the glass plate G. The surfactant may be selected from a group including anionic surfactants represented by alkylbenzenesulfonates, etc., or nonionic surfactants represented by polyoxyethylene alkyl ethers, etc. The surfactant is effective in the following aspects: extracting the residues of the organic main body on each main surface Ga and main surface Gb of the glass plate G and removing them from each main surface Ga and main surface Gb of the glass plate G.

More preferably, the alkaline cleaning liquid may also contain a chelating agent like the first cleaning liquid CS1 in order to prevent the calcium ions that are free in the alkaline cleaning liquid after being removed from the glass plate G from being attached to the main surfaces Ga and Gb of the glass plate G.

The rinsing section 5 is used to remove the second cleaning liquid CS2 attached to the glass plate G after passing through the second cleaning section 4. The rinsing section 5 includes an upper rinsing liquid supply section 5a and a lower rinsing liquid supply section 5b. The upper rinsing liquid supply section 5a supplies rinsing liquid to the first main surface Ga of the glass plate G. The lower rinsing liquid supply section 5b supplies rinsing liquid to the second main surface Gb of the glass plate G.

As a rinse liquid, pure water is used, for example, but it is not limited to this. For example, as a rinse liquid, pure water containing alkaline electrolyzed water with a pH of about 11 formed by electrolysis of a potassium carbonate aqueous solution with a small concentration can also be used. Thereby, each main surface Ga and main surface Gb of the glass plate G are negatively charged (covered by anions), and the calcium ions or organic matter, particles, etc. dispersed in the drainage are negatively charged and have a repelling effect, thereby preventing foreign matter from being attached to the main surface Ga and main surface Gb of the glass plate G after cleaning, which is particularly effective in reducing fine particles that cannot be seen in appearance inspection. When using pure water containing alkaline electrolyzed water, the pH of the pure water containing alkaline electrolyzed water can be set to 9~12, for example.

The rinsing section 5 includes a spray nozzle, which can remove the second cleaning liquid CS2 from the glass plate G by spraying a high-pressure cleaning liquid and performing cleaning. The rinsing section 5 can also remove the second cleaning liquid CS2 from the glass plate G by spraying a cleaning liquid mixed with air in pure water using a mix jet nozzle. In addition, the rinsing section 5 can also remove the second cleaning liquid CS2 from the glass plate G using a cleaning tool.

The drying section 6 is used to remove the rinsing liquid attached to the glass plate G after passing through the rinsing section 5. The drying section 6 includes an upper air knife 6a and a lower air knife 6b. The upper air knife 6a blows air to the first main surface Ga of the glass plate G after passing through the rinsing section 5. The lower air knife 6b blows air to the second main surface Gb of the glass plate G.

The conveying device 7 conveys the glass plate G from the first washing section 2 to the drying section 6. The conveying device 7 includes, for example, a roller conveyor, but is not limited to the above structure. The conveying device 7 includes a plurality of conveying rollers 7a arranged at predetermined intervals. Each conveying roller 7a is in contact with the second main surface Gb of the glass plate G and is driven to rotate, thereby conveying the glass plate G along the conveying direction X.

As shown in FIG3 , the cleaning step S2 includes: a first cleaning step S21, a liquid removal step S22, a second cleaning step S23, a rinsing step S24, and a drying step S25.

In the first cleaning step S21, in the first cleaning section 2, the glass plate G is transported along the transport direction X by the transport device 7, and the upper cleaning tool 8a and the lower cleaning tool 8b of the first cleaning section 2 are brought into contact with the first main surface Ga and the second main surface Gb of the glass plate G. Thus, the glass plate G is clamped by each cleaning tool 8a and the cleaning tool 8b. Each cleaning tool 8a and the cleaning tool 8b supply the acidic cleaning liquid as the first cleaning liquid CS1 to each main surface Ga and the main surface Gb of the glass plate G while rotating the cleaning member 10. Thus, the first main surface Ga and the second main surface Gb of the glass plate G are cleaned simultaneously.

In the liquid removal step S22, air is blown from the air knives 3a and 3b of the liquid removal section 3 to the glass plate G after passing through the first cleaning section 2, thereby removing the first cleaning liquid CS1 attached to the first main surface Ga and the second main surface Gb of the glass plate G.

In the second cleaning step S23, in the second cleaning section 4, the glass plate G is transported along the transport direction X, while the upper cleaning tool 15a and the lower cleaning tool 15b of the second cleaning section 4 are brought into contact with the first main surface Ga and the second main surface Gb of the glass plate G. Each cleaning tool 15a and the cleaning tool 15b supply the alkaline cleaning liquid as the second cleaning liquid CS2 to each main surface Ga and the main surface Gb of the glass plate G while rotating the cleaning member 10. In this way, the first main surface Ga and the second main surface Gb of the glass plate G are cleaned simultaneously.

In the rinsing step S24, the rinsing liquid is supplied from the rinsing liquid supplying parts 5a and 5b of the rinsing part 5 to the glass plate G after passing through the second cleaning part 4. In this way, the second cleaning liquid CS2 attached to the first main surface Ga and the second main surface Gb of the glass plate G can be removed.

In the drying step S25, air is blown from the air knives 6a and 6b of the drying section 6 to the glass sheet G after passing through the rinsing section 5. In this case, it is desirable to spray high-pressure air from the air knives 6a and 6b toward the glass sheet G. In this way, the rinsing liquid attached to the glass sheet G can be removed.

According to the manufacturing method of the glass plate G of the present embodiment, the calcium dirt transferred from the resin sheet RS to the glass plate G in the storage step S1 can be effectively removed by the first cleaning step S21. In addition, in the second cleaning step S23, the dirt containing organic matter can be effectively removed. Thereby, the cleaning power in the cleaning step S2 of the glass plate G can be improved. Here, it is speculated that the calcium dirt is generated by the additives (such as polyethylene alcohol or a copolymer of polyethylene alcohol and polypropylene) contained in the resin sheet RS absorbing moisture in the atmosphere, and the trace amount of calcium contained in the moisture in the atmosphere is precipitated, concentrated and attached to the glass. In addition, it is speculated that the dirt containing organic matter is generated by the penetration of various additives (such as hydrophobic substances) contained in the resin sheet RS.

FIG. 4 shows a second embodiment of the glass plate manufacturing method of the present invention. In this embodiment, the structure of the liquid removal step S22 is different from that of the first embodiment. In the first embodiment, the liquid removal section 3 of the cleaning device 1 includes an air knife, but the liquid removal section 3 in this embodiment includes a shower cleaning device that supplies a removal liquid for removing the first cleaning liquid CS1 attached to the glass plate G.

The liquid removal section 3 includes an upper side liquid removal supply section 17a and a lower side liquid removal supply section 17b. The upper side liquid removal supply section 17a supplies liquid removal to the first main surface Ga of the glass plate G. The lower side liquid removal supply section 17b supplies liquid removal to the second main surface Gb of the glass plate G.

The removal liquid supplied to the glass plate G includes, for example, pure water. The removal liquid is preferably supplied to the glass plate G in the form of heated warm water. The temperature of the removal liquid is preferably set to, for example, 40°C to 60°C, but is not limited to the above range.

The removal liquid may also contain alkaline electrolytic water. By using alkaline electrolytic water as the removal liquid, the main surfaces Ga and Gb of the glass plate G can be covered with anions, thereby preventing the particulate matter removed from the glass plate G and dispersed in the removal liquid from being attached to the main surfaces Ga and Gb of the glass plate G. In this way, the cleanliness of the main surfaces Ga and Gb of the glass plate G after the first cleaning step S21 can be improved.

The present invention is not limited to the structure of the implementation form described above, nor is it limited to the effects described above. The present invention can be modified in various ways without departing from the scope of the present invention.

In the above-mentioned embodiment, a method for manufacturing a glass plate G including a liquid removal step S22 between the first cleaning step S21 and the second cleaning step S23 is exemplified, but the present invention is not limited to the above-mentioned structure. In the present invention, for example, the liquid removal step S22 may be omitted.

In the above-mentioned embodiment, the cleaning tools 8a, 8b, 15a, and 15b are exemplified as cleaning tools in the shape of a disk (disc), but the present invention is not limited to the above-mentioned structure. The cleaning tools may also include other cleaning tools such as cleaning rollers.

The present invention may also include a liquid removal step for removing the second cleaning liquid CS2 (alkaline cleaning liquid) attached to the glass plate G due to the second cleaning step S23 between the second cleaning step S23 and the rinsing step S24.

[Implementation example]

The following describes an embodiment of the present invention, but the present invention is not limited to the embodiment. The inventors of the present invention conducted a test to confirm the quality of the glass plate manufactured by the present invention. The test was conducted by two methods, the first method and the second method, as described in detail below.

In the test using the first method, a clean, dry rectangular test sodium glass plate and a resin sheet were used. The size of the glass plate was 100 mm × 100 mm and the thickness was 0.7 mm. The size of the resin sheet was 150 mm × 150 mm. After the resin sheet and the glass plate were placed in contact for three months, the resin sheet was removed from the glass plate to prepare a test piece of a glass plate with calcium dirt and organic dirt formed on the surface (Example 1 to Example 5, Comparative Example 1).

In the experiment, after the glass plates of Examples 1 to 5 were cleaned with an acidic cleaning solution (first cleaning solution), the glass plates were cleaned with an alkaline cleaning solution (second cleaning solution). In this case, the glass plates of Examples 1 to 5 were cleaned with different concentrations of the acidic cleaning solution and the alkaline cleaning solution. In addition, the glass plate of Comparative Example 1 was cleaned with an alkaline cleaning solution (first cleaning solution) and then with an acidic cleaning solution (second cleaning solution).

Specifically, the cleaning liquid of a specified concentration is applied by spraying, a sponge made of polyvinyl alcohol (PVA) is soaked with the cleaning liquid and the glass plate is wiped for 30 seconds, then it is manually rinsed with pure water and dried with dry air.

The inventors of the present invention evaluated the cleaning results of the glass plates of Examples 1 to 5 and Comparative Example 1. The evaluation of the cleaning results was performed by the following inspection (visual inspection), namely, the presence or absence of dirt on the surface of the glass plate was visually confirmed by the reflection and transmission of light on the surface of the glass plate using a fluorescent lamp with an illumination of 1500 lux. In addition, the evaluation of the cleaning results was performed by the following visual inspection, namely, the reflection of light on the surface of the glass plate using a halogen lighting with a higher intensity of 10000 lux. The evaluation results were performed in three stages: ○ (good), △ (general), and × (bad).

The evaluation of ○ (good) in Table 1 indicates that in visual inspection, under the conditions of illuminance of 1500 lux from fluorescent lighting and 10000 lux from halogen lighting, a clean and transparent glass plate was obtained with no observed dot-shaped or line-shaped surface foreign matter or translucent spots caused by residual cleaning agent.

The evaluation of △ (normal) in Table 1 indicates that although no surface foreign matter was observed under fluorescent lighting illumination of 1500 lux, microscopic foreign matter residues or translucent spots that are considered to be film-like residues of seeping foreign matter or cleaning agent components were observed in visual inspection under the condition of illumination of 10000 lux emitted by halogen lighting.

On the other hand, the evaluation of × (bad) in Table 1 is made when the remnants of foreign matter or translucent spots are observed under visual inspection using illumination of 1500 lux emitted by a fluorescent lamp.

The test results are shown in Table 1. The concentration of the acidic cleaning solution indicates the concentration of glycolic acid (mass %), and the concentration of the alkaline cleaning solution indicates the total concentration of sodium hydroxide and potassium hydroxide (mass %). In the alkaline cleaning solution, the concentrations of sodium hydroxide and potassium hydroxide (mass %) are set to be the same.

As shown in Table 1, the cleaning results of Examples 1 to 5 were judged to be good and fair. In Examples 3 and 4, no dirt was confirmed in the visual inspection under fluorescent light, but in the visual inspection with strong illumination using a halogen lamp, some tiny foreign matter that was considered to be insufficient cleaning, or white opaque light spots that were considered to be caused by the residue of acid detergent or the residue of film-like foreign matter were observed.

On the other hand, in Comparative Example 1, the dirt containing organic matter could not be sufficiently removed from the glass plate, and was judged to be poorly cleaned.

Here, on the surface of the glass plate, calcium dirt is often attached after dirt containing organic matter that oozes out is attached. Therefore, in many cases, part or all of the surface of the dirt containing organic matter is covered with calcium dirt. Therefore, if cleaning is performed with an alkaline cleaning solution (first cleaning solution) and then with an acidic cleaning solution (second cleaning solution) as in the comparative example, the exposed portion of the surface of the dirt containing organic matter tends to be removed in the cleaning with the alkaline cleaning solution, and the calcium dirt tends to be removed in the cleaning with the acidic cleaning solution. As a result, it is speculated that the non-exposed portion of the surface of the dirt containing organic matter tends to remain, and the dirt containing organic matter cannot be fully removed from the glass plate. The test results confirmed that after the glass plate was cleaned with an acidic cleaning solution, it was cleaned with an alkaline cleaning solution, thereby improving the cleaning power.

In the test using the second method, a rectangular glass plate and a polyethylene foam resin sheet cleaned and dried by a prescribed method were used. The glass plate has a size of 370 mm × 470 mm and a thickness of 0.5 mm. The glass plate is an alkali-free borosilicate glass plate for liquid crystal displays (material: OA-11 manufactured by Nippon Electric Glass Co., Ltd.). The resin sheet has a size of 400 mm × 500 mm and a thickness of 0.085 mm.

A glass laminate is formed by overlapping a polyethylene foam resin sheet with a glass plate. A glass laminate is a set of a glass plate and a resin sheet, and a plurality of sets of glass laminates are stacked in a horizontal position. The plurality of sets of glass laminates are glass laminates reproduced in a storage state assumed to be loaded on a transport pallet.

The glass laminate was placed in a constant temperature and humidity tester, and an accelerated environmental test was performed by changing the temperature and humidity in the tester. The following describes the details of the accelerated environmental test.

In the test, the first step and the second step were repeated at different temperatures and humidity. Specifically, the combination of the first step and the second step was a cycle, and the cycle was repeated 180 times.

In the first step, set the test machine to high temperature and high humidity. The set temperature in the test machine in the first step is 50℃, and the set humidity is 70%. In the second step, set the test machine to normal temperature and humidity. The set temperature in the test machine in the second step is 25℃, and the set humidity is 50%.

The cycle of the first step and the second step is set as follows. First, the temperature and humidity of the first step are maintained for one hour. After that, it takes one hour to lower the temperature and humidity in the test machine to the conditions of the second step. Then, the temperature and humidity of the second step are maintained for one hour. After that, it takes one hour to raise the temperature and humidity in the test machine to the conditions of the first step. The maintenance, decrease, and increase of the temperature and humidity constitute a cycle. The cycle reproduces in a short time the changes in the temperature and humidity of the surrounding environment when the glass laminate is stored for one day. In the test, the glass laminate was stored for 180 days, which was simulated by repeating 180 cycles.

By the accelerated environmental test as described above, the components of the resin sheet are transferred to the glass plate to contaminate it. Afterwards, the resin sheet is removed from the glass plate to produce a test piece of a glass plate with calcium dirt and dirt containing organic matter formed on the surface (Example 6 to Example 10, Comparative Example 2).

The cleaning of the glass plate in the second method is performed by the cleaning device 1 of the first embodiment. In the cleaning of the glass plate by the cleaning device 1, in the rinsing step, cleaning condition 1 using pure water without alkaline electrolyzed water as the rinsing liquid and cleaning condition 2 using pure water containing alkaline electrolyzed water as the rinsing liquid are set.

The evaluation of the cleaning results was the same as the first method described above, and was performed by visual inspection of the surface of the glass plate using light emitted by a fluorescent lamp with an illumination of 1500 lux, and by visual inspection of the surface of the glass plate using light emitted by a halogen lamp with an illumination of 10000 lux. For Example 6 to Example 10 and Comparative Example 2, five glass plates were inspected each and evaluated in three stages: ○ (good), △ (fair), and × (bad).

Furthermore, in the test using the second method, the number of microscopic foreign matter (particles) larger than 1 μm on the surface of the cleaned glass plate was measured using a particle measuring machine G17200 manufactured by Hitachi High-Technologies Corporation. For each of Examples 6 to 10 and Comparative Example 2, one glass plate was measured and the results were compared. The number of particles was expressed by converting the number detected within 370 mm × 470 mm into the number per 1 m ² (1000 mm × 1000 mm).

The test results are shown in Table 2. The concentration of the acidic cleaning solution indicates the concentration of glycolic acid (mass %), and the concentration of the alkaline cleaning solution indicates the total concentration (mass %) of sodium hydroxide and potassium hydroxide. In the alkaline cleaning solution, the concentrations (mass %) of sodium hydroxide and potassium hydroxide are set to be the same. Regarding the results of the fluorescent light inspection and halogen inspection in Table 2, since there is no obvious difference between the glass plate after cleaning with cleaning condition 1 and the glass plate after cleaning with cleaning condition 2, the glass plate after cleaning with cleaning condition 1 is shown.

As shown in Table 2, the cleaning results of Examples 6 to 10 were judged to be good and fair. In Examples 7 and 8, the results of the fluorescent light inspection and the halogen inspection were both 100 to 200 particles/m ² , which were good.

In Example 6 and Example 10, no dirt was confirmed in the visual inspection using a fluorescent lamp, but in the visual inspection using a halogen lamp, very faint white spots were observed, which were believed to be caused by the residual detergent components, and the number of particles was a relatively high number of 500 to 1000 particles/ ^m2 .

In Example 9, no dirt was confirmed in the visual inspection using a fluorescent lamp, but in the visual inspection using a halogen lamp, tiny foreign matter that was considered to be insufficient cleaning was observed, and the number of particles was as high as 700 particles/ ^m2 . Furthermore, in the rinsing step, it was confirmed that under the cleaning condition 2 using pure water containing alkaline electrolyzed water, the number of particles in Examples 6 to 10 decreased compared with the cleaning condition 1 using pure water not containing alkaline electrolyzed water, and the effect of preventing foreign matter from re-attaching was achieved.

On the other hand, in Comparative Example 2, the dirt containing organic matter could not be sufficiently removed from the glass plate, and was judged as poor cleaning. The number of fine particles was as high as 10,000 pieces/m ² , and in the visual inspection, the foreign matter caused by the unevenness of the surface of the foamed resin sheet remained on the glass plate in an irregular shape. Therefore, Comparative Example 2 was poor.

1: Cleaning device

2: First cleaning section

2a: Upper cleaning machine, cleaning machine

2b: Lower side cleaning machine, cleaning machine

3: Liquid removal section

3a: Upper side air knife, air knife

3b: Lower side air knife, air knife

4: Second cleaning section

4a: Upper cleaning machine

4b: Lower side cleaning machine

5: Rinsing section

5a: Upper flushing liquid supply part, flushing liquid supply part

5b: Lower side flushing liquid supply part, flushing liquid supply part

6: Drying section

6a: Upper side air knife, air knife

6b: Lower side air knife, air knife

7: Transport device

7a: Transport roller

8a: Upper cleaning tools, cleaning tools

8b: Lower side cleaning tools, cleaning tools

9a: The main body of the upper cleaning tool

9b: The main body of the lower cleaning tool

15a: Upper cleaning tools, cleaning tools

15b: Lower side cleaning tools, cleaning tools

16a: The main body of the upper cleaning tool

16b: The main body of the lower cleaning tool

CS1: First cleaning solution

CS2: Second cleaning solution

G: Glass plate

Ga: first main surface, main surface

Gb: Second main surface, main surface

P: Pallet

PB: Bale body

RS: Resin sheet

S1: Storage step

S2: Cleaning step

SS: Storage space

X: Transport direction

Claims (9)

A method for manufacturing a glass plate includes: a storage step of storing a glass plate in contact with a resin sheet; and a cleaning step of cleaning the glass plate after the storage step; and the method for manufacturing the glass plate is characterized in that: the cleaning step includes: a first cleaning step of supplying a first cleaning liquid to the glass plate and cleaning the glass plate; and a second cleaning step of supplying a second cleaning liquid to the glass plate and cleaning the glass plate after the first cleaning step; the first cleaning liquid is an acidic cleaning liquid, the second cleaning liquid is an alkaline cleaning liquid, and the acidic cleaning liquid contains a hydroxy acid. A method for manufacturing a glass sheet as described in claim 1, wherein the hydroxy acid comprises glycolic acid. A method for manufacturing a glass sheet as described in claim 1, wherein the alkaline cleaning solution contains hydroxide. A method for manufacturing a glass sheet as described in claim 2, wherein the alkaline cleaning solution contains hydroxide. A method for manufacturing a glass plate as described in any one of claim 1 to claim 4, wherein the alkaline cleaning solution contains at least one of sodium hydroxide and potassium hydroxide. A method for manufacturing a glass plate as described in any one of claim 1 to claim 4, wherein in the first cleaning step, the glass plate is cleaned by bringing a cleaning tool into contact with the glass plate. A method for manufacturing a glass plate as described in any one of claim 1 to claim 4, wherein in the second cleaning step, the glass plate is cleaned by bringing a cleaning tool into contact with the glass plate. The method for manufacturing a glass plate as described in any one of claim 1 to claim 4 includes a liquid removal step of removing the first cleaning liquid attached to the glass plate by supplying a removal liquid to the glass plate after the first cleaning step and before the second cleaning step, wherein the removal liquid is warm water. The method for manufacturing a glass plate as described in any one of claims 1 to 4 includes, after the second cleaning step, a rinsing step of removing the second cleaning liquid attached to the glass plate by supplying a rinsing liquid to the glass plate, wherein the rinsing liquid contains alkaline electrolyzed water.