Glass plate manufacturing method

Abstract

This glass sheet manufacturing method comprises a storing step for storing a glass sheet in contact with a resin sheet and a cleaning step for cleaning the glass sheet after the storing step. Said cleaning step S2 includes: a first cleaning step S21 for cleaning the glass sheet G by supplying a first cleaning solution CS1 to the glass sheet G; and a second cleaning step S23 for cleaning the glass sheet G by supplying a second cleaning solution CS2 to the glass sheet G after the first cleaning step S21. The first cleaning solution CS1 is an acidic cleaning solution and the second cleaning solution CS2 is an alkaline cleaning solution.

Description

[Technical field]

[0001] The present invention relates to a method for producing a glass sheet. [Background technology]

[0002] In recent years, panel displays such as liquid crystal displays and organic electroluminescence displays have been moving toward higher definition. Accordingly, glass plates used as substrates for such displays are required to have dense electrical circuits formed thereon during the manufacturing process of such displays. Therefore, such glass plates are required to be highly clean and free of dust and dirt.

[0003] The manufacturing process of glass plates includes, for example, an unpacking process of taking out glass original plates stored on a pallet, a cutting process of cutting out glass plates of a predetermined size from the taken out glass original plates, an edge processing process of processing the edges of the glass plates, and a cleaning process of cleaning the edge-processed glass plates. Methods for cleaning glass plates include a method of cleaning glass plates transported in a predetermined direction with a cleaning tool such as a cleaning disk or a cleaning brush (roll brush) (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2017-14060 A Summary of the Invention [Problem to be solved by the invention]

[0005] The glass original plates supplied to the glass plate manufacturing process are stored while being loaded on a pallet, and a plurality of glass original plates may be stacked on the pallet with resin sheets interposed therebetween.

[0006] In this case, if the glass plate is stored on the pallet for a long period of time, calcium stains and stains containing organic matter may occur. Furthermore, these stains may adhere firmly to the glass plate and become difficult to remove from the glass plate during the cleaning process.

[0007] Therefore, an object of the present invention is to improve the cleaning power in the glass plate cleaning process. [Means for solving the problem]

[0008] The present invention has been made to solve the above-mentioned problems, and provides a method for manufacturing a glass plate, comprising: 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, wherein the cleaning step comprises: a first cleaning step of supplying a first cleaning liquid to the glass plate to clean the glass plate; and a second cleaning step of supplying a second cleaning liquid to the glass plate after the first cleaning step to clean the glass plate, wherein the first cleaning liquid is an acidic cleaning liquid, and the second cleaning liquid is an alkaline cleaning liquid.

[0009] According to intensive research by the present inventors, it has been confirmed that when a glass plate is stored for a long period of time with a resin sheet in contact with it, if the dirt transferred from the resin sheet to the surface of the glass plate contains calcium (hereinafter referred to as "calcium dirt"), it is more difficult to remove the calcium dirt from the glass plate by cleaning than other types of dirt.

[0010] The present inventors have found that calcium stains and stains containing organic matter can be effectively removed from a glass plate by performing a first cleaning step using an acidic cleaning solution as a first cleaning solution and then performing a second cleaning step using an alkaline cleaning solution as a second cleaning solution.

[0011] The acidic cleaning solution may contain a hydroxy acid. Examples of hydroxy acids (oxy acids) include glycolic acid, lactic acid, tartaric acid, citric acid, malic acid, and salicylic acid. Hydroxy acids are carboxylic acids that also have a hydroxyl group, and are highly water-soluble. In addition, the carboxyl group contained in the hydroxy acid molecule converts calcium ions (Ca 2+ ) through a chelating effect, absorbing and stabilizing calcium ions within one or more molecules, making it effective in removing calcium components that have adhered to the surface of glass plates.

[0012] The alkaline cleaning solution may include a hydroxide salt, for example sodium hydroxide and / or potassium hydroxide.

[0013] In the first cleaning step, the glass plate may be cleaned by bringing a cleaning tool into contact with the glass plate, thereby making it possible to efficiently perform the first cleaning step.

[0014] In the second cleaning step, the glass plate may be cleaned by contacting a cleaning tool with the glass plate, thereby making it possible to efficiently perform the second cleaning step.

[0015] The method further includes a step of removing the first cleaning liquid adhering to the glass plate by supplying a removing liquid to the glass plate after the first cleaning step and before the second cleaning step, the removing liquid being warm water. By removing the first cleaning liquid adhering to the glass plate after the first cleaning step through the removing liquid step, the glass plate can be more effectively cleaned with the second cleaning liquid in the subsequent second cleaning step.

[0016] The method further includes a rinsing step of removing the second cleaning solution adhering to the glass sheet by supplying a rinsing solution to the glass sheet after the second cleaning step, and the rinsing solution may include alkaline electrolyzed water. By covering the surface of the glass sheet with anions in the rinsing step, particulate matter dispersed in the rinsing solution can be prevented from re-adhering to the surface of the glass sheet, and the cleanliness of the surface of the glass sheet after the rinsing step can be increased. Effect of the Invention

[0017] According to the present invention, it is possible to improve the cleaning power in the process of cleaning a glass plate. [Brief description of the drawings]

[0018] [Figure 1] 1 is a cross-sectional view illustrating a method for producing a glass plate according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a cross-sectional view showing the configuration of a cleaning device in the first cleaning section and the second cleaning section. [Diagram 3] 1 is a flowchart showing a cleaning process. [Figure 4] FIG. 4 is a cross-sectional view showing a method for producing a glass plate according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings. Figures 1 to 3 show a first embodiment of a method for producing a glass plate according to the present invention.

[0020] 1, the method includes a storage step S1 for storing a glass sheet G, and a cleaning step S2 for cleaning the glass sheet G. The method may further include the above-mentioned unpacking step, cutting step, and edge processing step between the storage step S1 and the cleaning step S2. The method may further include an inspection step of the glass sheet G and a packaging step of loading the glass sheet G on a pallet as steps following the cleaning step S2.

[0021] In the storage step S1, the glass sheets G are managed in a state of a package PB. The package PB is formed by stacking a plurality of glass sheets G on a pallet P. In the storage step S1 of the present embodiment, the glass sheets G are stored in a flat position, but the glass sheets G may be stored in an inclined position.

[0022] The glass sheet G is formed, for example, by cutting a long glass ribbon formed by an overflow downdraw method. In the overflow downdraw method, molten glass is poured into an overflow groove provided in the upper part of a forming body having a substantially wedge-shaped cross section, and the molten glass overflowing on both sides from the overflow groove is allowed to flow down along both sidewalls of the forming body and is fused and integrated at the lower end of the forming body to continuously form a glass ribbon. The glass sheet G can be produced not only by the overflow downdraw method, but also by various other forming methods such as the float method.

[0023] The glass plate G is configured to have a rectangular shape, but is not limited to this 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 a guaranteed surface, and the second main surface Gb is a non-guaranteed surface. Here, the "guaranteed surface" refers to a surface on the side on which a film formation process such as a transparent conductive film is performed, for example, in the manufacturing process of a display.

[0024] The glass plate G is made of, for example, silicate glass or silica glass, and is preferably made of borosilicate glass, soda-lime glass, aluminosilicate glass, chemically strengthened glass, or alkali-free glass. Here, alkali-free glass refers to glass that does not substantially contain an alkali component (alkali metal oxide), and specifically refers to glass having an alkali component weight ratio of 3000 ppm or less. The alkali component weight ratio in the present invention is preferably 1000 ppm or less, more preferably 500 ppm or less, and most preferably 300 ppm or less.

[0025] A resin sheet RS is laid over each glass plate G. The resin sheet RS prevents the glass plates G from coming into contact with each other when in the package PB.

[0026] The resin sheet RS is composed of a rectangular sheet having a surface area larger than that of the glass plate G. The resin sheet RS is composed of, for example, a foamed resin sheet made of a resin mainly composed of polyethylene, a resin protective film, etc. The resin sheet RS may contain an antistatic agent such as a polymer-type antistatic agent, or a surfactant such as an anionic surfactant or a nonionic surfactant.

[0027] In the storage step S1, the package PB is stored for, for example, several days to a year. The longer the storage period, the more soiled the glass plate G becomes, and the more pronounced the effect of improving the cleaning power of the present invention becomes. For this reason, the storage period is preferably two months or more, and more preferably four months or more. After the storage step S1, the package PB is carried out of the storage space SS.

[0028] The glass sheet G taken out of the package PB is supplied to the cleaning step S2. In this case, the resin sheet RS is peeled off from the glass sheet G. In the cleaning step S2, the glass sheet G is cleaned by the cleaning device 1 shown in FIG.

[0029] The cleaning apparatus 1 mainly includes a first cleaning unit 2 that cleans the glass sheet G while supplying a first cleaning liquid CS1 to the glass sheet G, a liquid draining unit 3 that removes the first cleaning liquid CS1 adhering to the glass sheet G, a second cleaning unit 4 that cleans the glass sheet G while supplying a second cleaning liquid CS2 to the glass sheet G, a rinsing unit 5 that removes the second cleaning liquid CS2 adhering to the glass sheet G while supplying a rinsing liquid to the glass sheet G, and a drying unit 6. In addition, the cleaning apparatus 1 includes a conveying device 7 that conveys the glass sheet G along a predetermined conveying direction X.

[0030] The first cleaning section 2 includes an upper cleaning machine 2a for cleaning a first main surface Ga of the glass sheet G, and a lower cleaning machine 2b for cleaning a second main surface Gb of the glass sheet G.

[0031] The upper cleaning machine 2a includes an upper cleaning tool 8a that contacts the first principal surface Ga and a main body 9a that supports the upper cleaning tool 8a. The lower cleaning machine 2b includes a lower cleaning tool 8b that contacts the second principal surface Gb and a main body 9b that supports the lower cleaning tool 8b. The upper cleaning machine 2a and the lower cleaning machine 2b are of the same type.

[0032] The configuration of each of the cleaners 2a and 2b will be described below using the upper cleaner 2a shown in Fig. 2 as an example. The upper cleaner 8a is configured in a disk shape, but is not limited to this shape. The upper cleaner 8a includes a cleaning member 10 that contacts the first main surface Ga of the glass sheet G and a shaft portion 11 that supports the cleaning member 10.

[0033] The cleaning member 10 is formed into a disk shape (circular plate shape) from, for example, a foamed resin molded body or a foamed rubber molded body (foam sponge), or a felt-like fiber molded body (felt sponge). The cleaning member 10 is not limited to this configuration, and may be formed of a brush.

[0034] The cleaning member 10 has a supply hole 12 for supplying the first cleaning liquid CS1 to the glass sheet G. The shaft portion 11 is configured in a tubular shape, and allows the first cleaning liquid CS1 to pass through the inside. The shaft portion 11 is in communication with the supply hole 12 of the cleaning member 10.

[0035] The main body 9a includes a storage tank 13 that stores the first cleaning liquid CS1, a bearing 14 that rotatably supports the shaft 11 of the first cleaning tool, and a drive unit (not shown) that rotates the shaft 11.

[0036] The storage tank 13 stores an acidic cleaning liquid as the first cleaning liquid CS1. The acidic cleaning liquid is, for example, an aqueous solution containing a hydroxy acid. Examples of hydroxy acids include glycolic acid, lactic acid, tartaric acid, citric acid, malic acid, and salicylic acid. Hydroxy acids are carboxylic acids that also have a hydroxyl group, and are highly water-soluble. In addition, the carboxyl groups contained in the hydroxy acid molecules react with calcium ions (Ca 2+) by a chelating effect, and calcium ions are taken in and stabilized in one molecule or multiple molecules, so that it is effective in removing calcium components fixed to each of the main surfaces Ga and Gb of the glass plate G. For example, when glycolic acid is used as the acidic cleaning solution, its concentration is preferably 1.5 to 10%, but is not limited to this range. The acidic cleaning solution may contain one or more types of hydroxy acids.

[0037] In addition, the first cleaning liquid CS1 may contain a surfactant for cleaning and removing dirt containing organic matter on the glass sheet G. The surfactant may be selected from the group consisting of anionic surfactants represented by sodium alkylbenzene sulfonate and the like, and nonionic surfactants represented by polyoxyethylene alkyl ether and the like. The surfactant is effective in capturing organic-based dirt in the dirt transferred from the resin sheet RS to each of the main surfaces Ga and Gb of the glass sheet G, and removing it from each of the main surfaces Ga and Gb of the glass sheet G.

[0038] The acidic cleaning solution is used to remove calcium ions (Ca 2+ ) to the respective main surfaces Ga and Gb of the glass sheet G. The added chelating aid may further contain a chelating aid that preferentially captures calcium ions in order to prevent redeposition of the calcium ions on the respective main surfaces Ga and Gb of the glass sheet G. As the chelating aid, sodium tripolyphosphate, EDTA (ethylenediaminetetraacetic acid), NTA (nitrilotriacetic acid), sodium citrate, or various organic polymer chelating aids may be used, or an inorganic substance such as zeolite that selectively adsorbs calcium ions may be used.

[0039] The storage tank 13 may be provided with a heater for heating the first cleaning solution CS1. In this case, the temperature of the first cleaning solution CS1 is preferably set to 40 to 50° C., but is not limited to this range.

[0040] The first cleaning unit 2 can perform scrubbing cleaning on the glass plate G by rotating the shaft portion 11 using the drive unit while the cleaning tools 8a, 8b are in contact with the main surfaces Ga, Gb of the glass plate G.

[0041] The draining unit 3 is for removing the first cleaning liquid CS1 adhering to the glass sheet G that has passed through the first cleaning unit 2. The draining unit 3 includes an upper air knife 3a and a lower air knife 3b. The draining unit 3 can remove the first cleaning liquid CS1 from the glass sheet G by blowing air from each of the air knives 3a and 3b onto each of the main surfaces Ga and Gb of the glass sheet G.

[0042] The second cleaning unit 4 includes an upper cleaning machine 4a and a lower cleaning machine 4b capable of scrubbing and cleaning the glass sheet 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 unit 4 have the same structure as the upper cleaning machine 2a and the lower cleaning machine 2b in the first cleaning unit 2.

[0043] However, the second cleaning section 4 differs 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 salt, 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 0.5 to 10%, more preferably 1.5 to 10%. The second cleaning liquid CS2 may contain a surfactant or a chelating agent. The temperature of the second cleaning liquid CS2 is preferably 40 to 50° C., but is not limited to this range.

[0044] The alkaline cleaning liquid is not limited to hydroxide salts and may contain carbonate salts. Examples of carbonate salts that can be used include sodium carbonate, potassium carbonate, sodium sesquicarbonate, and sodium hydrogencarbonate (sodium bicarbonate). In addition, the alkaline cleaning liquid may contain an alkali builder assistant such as silicate salt.

[0045] The alkaline cleaning liquid can more effectively remove other contaminants, including organic matter, from the glass sheet G. In addition, by alkalizing each of the main surfaces Ga, Gb of the glass sheet G and causing them to retain a negative charge, it becomes possible to particularly effectively remove highly polar surfactant components that remain adsorbed on each of the main surfaces Ga, Gb of the glass sheet G after using the first cleaning liquid CS1 (acidic cleaning agent).

[0046] The alkaline cleaning liquid may contain a surfactant component for effectively removing organic-containing dirt and residues of the acidic cleaning agent on the glass sheet G. The surfactant may be selected from the group consisting of anionic surfactants such as sodium alkylbenzene sulfonate and nonionic surfactants such as polyoxyethylene alkyl ether. The surfactant is effective in capturing organic-based residues on each of the main surfaces Ga and Gb of the glass sheet G and removing them from each of the main surfaces Ga and Gb of the glass sheet G.

[0047] More preferably, the alkaline cleaning solution may contain a chelating agent similar to the first cleaning solution CS1 in order to prevent calcium ions removed from the glass sheet G and liberated in the alkaline cleaning solution from re-adhering to each of the main surfaces Ga, Gb of the glass sheet G.

[0048] The rinsing section 5 is for removing the second cleaning liquid CS2 adhering to the glass sheet G that has passed 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 a rinsing liquid to a first main surface Ga of the glass sheet G. The lower rinsing liquid supply section 5b supplies a rinsing liquid to a second main surface Gb of the glass sheet G.

[0049] As the rinse liquid, for example, pure water is used, but is not limited thereto. For example, pure water containing alkaline electrolytic water with a pH of about 11 formed by electrolysis from a low-concentration potassium carbonate aqueous solution may be used as the rinse liquid. This causes each of the main surfaces Ga and Gb of the glass sheet G to be negatively charged (covered with anions), and calcium ions, organic matter, particles, etc. dispersed in the drainage liquid to be negatively charged and have a repulsive effect, which can prevent foreign matter from reattaching to the main surfaces Ga and Gb of the glass sheet G after cleaning, and is particularly effective in reducing microparticles that are invisible during visual inspection. When using pure water containing alkaline electrolytic water, the pH of the pure water containing alkaline electrolytic water can be set to, for example, 9 to 12.

[0050] The rinsing unit 5 is equipped with a spray nozzle, and can remove the second cleaning liquid CS from the glass sheet G by spraying a high-pressure rinsing liquid to clean the glass sheet G. The rinsing unit 5 may remove the second cleaning liquid CS2 from the glass sheet G by spraying a rinsing liquid obtained by mixing air into pure water using a mixed jet nozzle. The rinsing unit 5 may also remove the second cleaning liquid CS from the glass sheet G by using a cleaning tool.

[0051] The drying section 6 is for removing the rinsing liquid adhering to the glass sheet G that has passed 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 onto a first main surface Ga of the glass sheet G that has passed through the rinsing section 5. The lower air knife 6b blows air onto a second main surface Gb of the glass sheet G.

[0052] The conveying device 7 conveys the glass sheet G from the first cleaning section 2 to the drying section 6. The conveying device 7 is configured, for example, by a roller conveyor, but is not limited to this configuration. The conveying device 7 includes a plurality of conveying rollers 7a arranged at a predetermined interval. Each of the conveying rollers 7a conveys the glass sheet G along the conveying direction X by being rotated while contacting the second main surface Gb of the glass sheet G.

[0053] As shown in FIG. 3, the cleaning process S2 includes a first cleaning process S21, a draining process S22, a second cleaning process S23, a rinsing process S24, and a drying process S25.

[0054] In the first cleaning step S21, in the first cleaning section 2, the glass sheet G is transported by the transport device 7 along the transport direction X, while the upper cleaning tool 8a and the lower cleaning tool 8b in the first cleaning section 2 are brought into contact with the first principal surface Ga and the second principal surface Gb of the glass sheet G. As a result, the glass sheet G is sandwiched between the cleaning tools 8a and 8b. Each of the cleaning tools 8a and 8b rotates the cleaning member 10 while supplying an acidic cleaning solution as the first cleaning solution CS1 to each of the principal surfaces Ga and Gb of the glass sheet G. As a result, the first principal surface Ga and the second principal surface Gb of the glass sheet G are simultaneously cleaned.

[0055] In the draining process S22, air is blown from each air knife 3a, 3b of the draining section 3 onto the glass sheet G that has passed through the first cleaning section 2, thereby removing the first cleaning liquid CS1 adhering to the first principal surface Ga and the second principal surface Gb of the glass sheet G.

[0056] In the second cleaning step S23, while the glass sheet G is transported in the transport direction X in the second cleaning unit 4, the upper cleaning tool 15a and the lower cleaning tool 15b in the second cleaning unit 4 are brought into contact with the first principal surface Ga and the second principal surface Gb of the glass sheet G. Each of the cleaning tools 15a, 15b rotates the cleaning member 10 while supplying an alkaline cleaning solution as the second cleaning solution CS2 to each of the principal surfaces Ga, Gb of the glass sheet G. As a result, the first principal surface Ga and the second principal surface Gb of the glass sheet G are simultaneously cleaned.

[0057] In the rinsing step S24, a rinsing liquid is supplied from each of the rinsing liquid supply parts 5a and 5b of the rinsing part 5 to the glass sheet G that has passed through the second cleaning part 4. This makes it possible to remove the second cleaning liquid CS2 adhering to the first principal surface Ga and the second principal surface Gb of the glass sheet G.

[0058] In the drying step S25, air is blown from the air knives 6a, 6b of the drying section 6 onto the glass sheet G that has passed through the rinsing section 5. In this case, for example, it is desirable to spray high-pressure air from the air knives 6a, 6b toward the glass sheet G. This makes it possible to remove the rinsing liquid adhering to the glass sheet G.

[0059] According to the manufacturing method of the glass sheet G of this embodiment, calcium stains transferred from the resin sheet RS to the glass sheet G in the storage step S1 can be effectively removed in the first cleaning step S21. Also, in the second cleaning step S23, stains containing organic matter can be effectively removed. This makes it possible to improve the cleaning power in the cleaning step S2 of the glass sheet G. Here, it is presumed that calcium stains are generated when a trace amount of calcium contained in moisture in the air precipitates and concentrates and adheres to the glass during the process in which additives (e.g., polyethylene glycol or a copolymer of polyethylene glycol and polypropylene) contained in the resin sheet RS absorb moisture in the air. Also, it is presumed that stains containing organic matter are generated by bleeding out various additives (e.g., hydrophobic substances) contained in the resin sheet RS.

[0060] 4 shows a second embodiment of the method for producing a glass sheet according to the present invention. In this embodiment, the configuration of the liquid draining step S22 is different from that of the first embodiment. In the first embodiment, the liquid draining unit 3 of the cleaning device 1 is configured by an air knife, but in this embodiment, the liquid draining unit 3 is configured by a shower cleaning device that supplies a removal liquid to remove the first cleaning liquid CS1 adhering to the glass sheet G.

[0061] The liquid drainer 3 includes an upper removing liquid supply unit 17a and a lower removing liquid supply unit 17b. The upper removing liquid supply unit 17a supplies the removing liquid to a first main surface Ga of the glass sheet G. The lower removing liquid supply unit 17b supplies the removing liquid to a second main surface Gb of the glass sheet G.

[0062] The removing liquid supplied to the glass sheet G is composed of, for example, pure water. The removing liquid is preferably supplied to the glass sheet G in the form of heated water. The temperature of the removing liquid is preferably, for example, 40 to 60° C., but is not limited to this range.

[0063] The removing solution may contain alkaline electrolyzed water. By using alkaline electrolyzed water as the removing solution, each of the main surfaces Ga, Gb of the glass sheet G is covered with anions, and particulate matter removed from the glass sheet G and dispersed in the removing solution can be prevented from reattaching to each of the main surfaces Ga, Gb of the glass sheet G. This can increase the cleanliness of each of the main surfaces Ga, Gb of the glass sheet G after the first cleaning step S21.

[0064] The present invention is not limited to the configuration of the above embodiment, nor is it limited to the above-mentioned effects and advantages. Various modifications of the present invention are possible without departing from the spirit and scope of the present invention.

[0065] In the above embodiment, the method for manufacturing the glass sheet G including the draining step S22 between the first cleaning step S21 and the second cleaning step S23 is illustrated, but the present invention is not limited to this configuration. In the present invention, for example, the draining step S22 may be omitted.

[0066] In the above embodiment, the cleaning tools 8a, 8b, 15a, and 15b are illustrated as being disk-shaped, but the present invention is not limited to this configuration. The cleaning tools may be cleaning rollers or other cleaning tools.

[0067] The present invention may include a liquid draining step between the second cleaning step S23 and the rinsing step S24, in which the second cleaning liquid CS2 (alkaline cleaning liquid) adhered to the glass sheet G in the second cleaning step S23 is removed. EXAMPLES

[0068] Hereinafter, examples of the present invention will be described, but the present invention is not limited to these examples. The inventors conducted tests to confirm the quality of the glass plate manufactured by the present invention. The tests were conducted by two methods, a first method and a second method, as described in detail below.

[0069] In the test by the first method, a cleaned and dried rectangular test soda 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 storing the resin sheet in contact with the glass plate for three months, the resin sheet was removed from the glass plate to prepare test pieces of the glass plate (Examples 1 to 5, Comparative Example 1) on whose surfaces calcium stains and stains containing organic matter were formed.

[0070] In the test, the glass plates according to Examples 1 to 5 were washed with an acidic cleaning solution (first cleaning solution), and then washed with an alkaline cleaning solution (second cleaning solution). In this case, the glass plates according to Examples 1 to 5 were washed with different concentrations of the acidic cleaning solution and the alkaline cleaning solution. In addition, the glass plate according to Comparative Example 1 was washed with an alkaline cleaning solution (first cleaning solution), and then washed with an acidic cleaning solution (second cleaning solution).

[0071] Specifically, the cleaning solution of a predetermined concentration was sprayed onto the glass plate using a shower, and the glass plate was rubbed for 30 seconds using a polyvinyl alcohol (PVA) sponge impregnated with the cleaning solution, after which the glass plate was manually rinsed with pure water and dried with dry air.

[0072] The present inventors evaluated the cleaning results for the glass plates according to Examples 1 to 5 and Comparative Example 1. The cleaning results were evaluated by a visual inspection (visual inspection) in which the presence or absence of dirt on the surface of the glass plate was visually confirmed by utilizing the reflection and transmission of light on the surface of the glass plate using fluorescent lighting with an illuminance of 1500 lux. In addition, the cleaning results were evaluated by a visual inspection using the reflection of light on the surface of the glass plate using a stronger halogen lighting with an illuminance of 10000 lux. The evaluation results were graded into three levels: ◯ (good), △ (normal), and × (unacceptable).

[0073] A rating of ○ (good) in Table 1 indicates that, in visual inspection under conditions of 1,500 lux illumination from fluorescent lighting and 10,000 lux illumination from halogen lighting, a clean and transparent glass plate was obtained with no observable spot-like or linear surface foreign matter or translucent unevenness due to residual detergent.

[0074] A rating of △ (normal) in Table 1 indicates that no surface foreign matter was observed under fluorescent lighting with an illuminance of 1,500 lux, but visual inspection under halogen lighting with an illuminance of 10,000 lux found minute foreign matter remaining, or translucent unevenness thought to be bleed-out foreign matter or a thin film-like residue of detergent ingredients.

[0075] On the other hand, a rating of × (unacceptable) in Table 1 is given when residual foreign matter or uneven translucency is observed during visual inspection using fluorescent lighting with an illuminance of 1,500 lux.

[0076] The test results are shown in Table 1. The concentration of the acidic cleaning solution indicates the concentration (mass%) of glycolic acid, 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 were the same. [Table 1]

[0077] As shown in Table 1, the cleaning results were judged to be good and normal for Examples 1 to 5. Of these, in Examples 3 and 4, no dirt was found in visual inspection with a fluorescent lamp, but in visual inspection with strong illumination using a halogen lamp, minute foreign matter thought to be slightly insufficient for cleaning and thin opaque white unevenness thought to be caused by remaining acid detergent or remaining film-like foreign matter were observed.

[0078] On the other hand, in Comparative Example 1, the dirt containing organic matter could not be sufficiently removed from the glass plate, and cleaning was judged to be insufficient.

[0079] Here, calcium stains are often attached to the surface of the glass plate after organic stains due to bleed-out are attached. Therefore, in many cases, a part or all of the surface of the organic stains is covered with calcium stains. Therefore, when the glass plate is washed 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 part of the organic stains on the surface is removed by the alkaline cleaning solution, and the calcium stains are removed by the acidic cleaning solution. As a result, the non-exposed part of the organic stains on the surface tends to remain, and it is presumed that the organic stains could not be sufficiently removed from the glass plate. From the test results, it was confirmed that the cleaning power was improved by washing the glass plate with an acidic cleaning solution and then washing the glass plate with an alkaline cleaning solution.

[0080] In the test by the second method, a rectangular glass plate cleaned and dried by a predetermined method and a polyethylene foam resin sheet were used. The size of the glass plate was 370 mm × 470 mm, and the thickness was 0.5 mm. This glass plate was an alkali-free borosilicate glass plate for liquid crystal displays (material: OA-11 manufactured by Nippon Electric Glass Co., Ltd.). The size of the resin sheet was 400 mm × 500 mm, and the thickness was 0.085 mm.

[0081] A polyethylene foam resin sheet was laminated on a glass plate to form a glass laminate. A combination of one glass plate and one resin sheet constitutes one glass laminate set, and multiple sets of glass laminates were laminated in a horizontal position. These multiple sets of glass laminates were created to simulate the storage state of the glass laminates loaded on a pallet for transportation.

[0082] This glass laminate was placed in a thermo-hygroscopic tester, and an accelerated environmental test was carried out by changing the temperature and humidity inside the tester. The details of the accelerated environmental test will be described below.

[0083] In this test, the first and second steps were repeated at different temperatures and humidities. Specifically, one cycle was defined as a combination of the first and second steps, and this cycle was repeated 180 times.

[0084] In the first step, the inside of the test machine was set to high temperature and high humidity. The temperature inside the test machine in the first step was set to 50°C, and the humidity was set to 70%. In the second step, the inside of the test machine was set to normal temperature and normal humidity. The temperature inside the test machine in the second step was set to 25°C, and the humidity was set to 50%.

[0085] The cycle of the first and second steps was set as follows. First, the temperature and humidity of the first step were maintained for one hour. Then, the temperature and humidity in the tester were decreased for one hour until the conditions of the second step were reached. Then, the temperature and humidity of the second step were maintained for one hour. Then, the temperature and humidity in the tester were increased for one hour until the conditions of the first step were reached. The above-mentioned maintenance, decrease, and increase of the temperature and humidity constitute one cycle. This one cycle reproduces in a short period of time the changes in temperature and humidity of the surrounding environment when the glass laminate is stored for one day. In this test, the condition of the glass laminate stored for 180 days was virtually reproduced by repeating 180 cycles.

[0086] The components of the resin sheet were transferred onto the glass plate by the accelerated environmental test described above to cause contamination. After that, the resin sheet was removed from the glass plate to prepare test pieces of the glass plate (Examples 6 to 10, Comparative Example 2) with calcium stains and stains containing organic matter formed on the surface.

[0087] The cleaning of the glass plate in this second method was performed by the cleaning apparatus 1 according to the first embodiment. In the cleaning of the glass plate by the cleaning apparatus 1, cleaning condition 1 in which pure water not containing alkaline electrolyzed water was used as a rinsing liquid in the rinsing step, and cleaning condition 2 in which pure water containing alkaline electrolyzed water was used were provided.

[0088] The cleaning results were evaluated by visually inspecting the surfaces of the glass plates using fluorescent light with an illuminance of 1500 lux and halogen lighting with an illuminance of 10000 lux, as in the first method described above. Five glass plates were inspected for each of Examples 6 to 10 and Comparative Example 2, and were evaluated on a three-level scale of ○ (good), △ (normal), and × (unacceptable).

[0089] Furthermore, in the test relating to the second method, the number of minute foreign objects (particles) of 1 μm or more on the surface of the glass plate after cleaning was measured using a particle measuring instrument GI7200 manufactured by Hitachi High-Tech 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 calculated by dividing the number of particles detected within an area of ​​370 mm × 470 mm by 1 m. 2 The figures are converted into the number per 1000mm x 1000mm.

[0090] The test results are shown in Table 2. The concentration of the acidic cleaning solution indicates the concentration (mass%) of glycolic acid, and the concentration of the alkaline cleaning solution indicates the combined concentration (mass%) of sodium hydroxide and potassium hydroxide. In the alkaline cleaning solution, the concentrations (mass%) of sodium hydroxide and potassium hydroxide were the same. The results of the fluorescent light test and halogen test in Table 2 showed no significant difference between the glass plate after cleaning under cleaning condition 1 and the glass plate after cleaning under cleaning condition 2, so the results for the glass plate after cleaning under cleaning condition 1 are shown. [Table 2]

[0091] As shown in Table 2, the cleaning results were judged to be good and normal for Examples 6 to 10. Among them, for Examples 7 and 8, the particle count was 100 to 200 particles / m along with the results of the fluorescent lamp test and halogen test. 2 There were few, and it was good.

[0092] In Examples 6 and 10, no stains were observed in visual inspection using a fluorescent lamp, but in visual inspection using a halogen lamp, very thin white unevenness was observed, which was thought to be caused by residual detergent components, and the particle count was 500 to 1000 particles / m. 2 showed a relatively high figure.

[0093] In Example 9, no dirt was found in the visual inspection using a fluorescent lamp, but minute foreign matter thought to be due to insufficient cleaning was observed in the visual inspection using a halogen lamp, and the particle count was 700 pieces / m 2 In the rinsing process, the particle count was reduced in cleaning condition 2, which uses pure water containing alkaline electrolyzed water, compared with cleaning condition 1, which uses pure water not containing alkaline electrolyzed water, in all of Examples 6 to 10, demonstrating the effect of preventing reattachment of foreign matter.

[0094] On the other hand, in Comparative Example 2, dirt including organic matter could not be sufficiently removed from the glass plate, and cleaning was judged to be insufficient. The particle value was also 10,000 pieces / m 2 In the visual inspection, bleeding marks (striped unevenness) were observed on the glass plate due to irregularly shaped foreign matter caused by the unevenness of the surface of the foamed resin sheet, and Comparative Example 2 was therefore determined to be defective. [Explanation of symbols]

[0095] 8a Upper cleaning tool 8b Lower cleaning tool 15a Upper cleaning tool 15b Lower cleaning tool CS1 First Cleaning Solution CS2 Second Cleaning Solution G Glass plate RS Resin Sheet S1 Storage process S2 cleaning process S21 First cleaning process S22 Draining process S23 Second cleaning process S24 Rinse process

Claims

1. A method for producing a glass plate, comprising: 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, The cleaning step includes a first cleaning step of supplying a first cleaning liquid to the glass plate to clean the glass plate, and a second cleaning step of supplying a second cleaning liquid to the glass plate after the first cleaning step to clean the glass plate, 13. A method for producing a glass plate, comprising the steps of: (a) forming a first cleaning liquid on a substrate; (b) cleaning the substrate with a first cleaning liquid; and (c) cleaning the substrate with a second cleaning liquid.

2. The method for producing a glass sheet according to claim 1 , wherein the hydroxy acid includes glycolic acid.

3. The method for producing a glass sheet according to claim 1 or 2, wherein the alkaline cleaning liquid contains a hydroxide salt.

4. The method for producing a glass sheet according to claim 1 , wherein the alkaline cleaning liquid contains at least one of sodium hydroxide and potassium hydroxide.

5. The method for producing a glass plate according to claim 1 , wherein in the first cleaning step, the glass plate is cleaned by bringing a cleaning tool into contact with the glass plate.

6. The method for producing a glass plate according to claim 1 , wherein in the second cleaning step, the glass plate is cleaned by bringing a cleaning tool into contact with the glass plate.

7. a liquid removing step of removing the first cleaning liquid adhering to the glass plate by supplying a removing liquid to the glass plate after the first cleaning step and before the second cleaning step, The method for producing a glass sheet according to claim 1 , wherein the removing liquid is hot water.

8. a rinsing step of removing the second cleaning liquid adhering to the glass plate by supplying a rinsing liquid to the glass plate after the second cleaning step, The method for producing a glass sheet according to claim 1 , wherein the rinsing liquid contains alkaline electrolyzed water.

Images