JP2017120332A - Cleaning fluid for glass substrate for liquid crystal, and cleaning method for glass substrate for liquid crystal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cleaning fluid for a glass substrate for liquid crystal that can effectively remove an adhesive foreign material adhered to a surface of a glass substrate due to reception of load and an adhesive foreign material deteriorated due to lapse of time.SOLUTION: There is provided a cleaning fluid for a glass substrate for liquid crystal that has a cloudy point determined by the concentration of a cleaning agent and the concentration of an alkaline component, where the concentration of the cleaning agent is 1.5% to 4%; the alkaline component is formed of one or more alkaline components selected from KOH, NaOH, ETDA-4Na, ETDA-4K, NaPO, and KPO; and the cloudy point is 60°C or more.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a liquid crystal glass substrate cleaning liquid and a liquid crystal glass substrate cleaning method.

  When transporting the molded glass substrate for liquid crystal, the recycled paper and the glass substrate may be alternately stacked and stacked on a pallet on which the glass substrate is tilted. In this case, the load of the glass substrate loaded later is applied to the glass substrate loaded previously. When recycled paper is used as the paper sandwiched between the glass substrates, sticky foreign substances having adhesiveness derived from ink, resin components, or the like contained in the recycled paper may adhere to the glass substrate. The adhesive foreign matter attached to the glass substrate previously loaded on the pallet is pressed against the glass substrate under the above load, and adheres more firmly to the glass substrate than the foreign matter attached to the glass substrate subsequently loaded on the pallet. Tend. Therefore, in order to remove the sticking foreign matter adhering to the surface of the glass substrate, as disclosed in Patent Document 1, a method of cleaning the surface of the glass substrate using an inorganic alkaline cleaning agent is used.

JP 2001-181686 A

  The above-mentioned adhesive foreign matter is, for example, when the glass substrate is stored for a long period of time, for example, several weeks to several months or more, and changes in quality over time to increase the adhesiveness or solidify. Then, removal becomes difficult.

  Therefore, the present invention provides a cleaning liquid for a glass substrate for liquid crystal, which can effectively remove adhesive foreign matter adhering to the surface of the glass substrate under load, and adhesive foreign matter that has changed in quality over time, and liquid crystal glass It is an object of the present invention to provide a method for cleaning a substrate.

One aspect of the present invention is a cleaning liquid for a glass substrate for liquid crystal,
A diluted solution obtained by diluting the cleaning agent with water having a concentration of 1.5% to 4%, KOH, NaOH, ETDA-4Na, ETDA-4K, Na ₄ P ₂ O ₇ , K ₄ P ₂ O ₇ The alkali component was added to the diluent so that the total concentration of one or more alkali components selected from 1 to 4% was obtained.
It is characterized by that.

Another aspect of the present invention is a liquid crystal glass substrate cleaning liquid having a cloud point determined by the concentration of a cleaning agent and the concentration of an alkali component,
The concentration of the cleaning agent is 1.5% to 4%,
The alkaline component comprises one or more alkaline components selected from KOH, NaOH, ETDA-4Na, ETDA-4K, Na ₄ P ₂ O ₇ , K ₄ P ₂ O ₇ ,
The cloud point is 60 ° C. or higher.
It is characterized by that.

The alkaline component is KOH;
The concentration of the KOH is preferably 1% to 4%.

  It is preferable that the cleaning agent includes a surfactant and includes an inorganic alkaline cleaning agent having a cloud point.

Another aspect of the present invention is a method for cleaning a glass substrate for liquid crystal, which includes a cleaning step of removing foreign matter attached to the glass substrate using the liquid crystal glass substrate cleaning liquid described above,
Prior to the cleaning step, the glass substrate is laminated with recycled paper sandwiched therebetween,
The foreign matter is an adhesive foreign matter derived from a substance contained in the recycled paper.
It is characterized by that.

  In the cleaning step, it is preferable that the temperature of the cleaning liquid is higher than 60 ° C.

  ADVANTAGE OF THE INVENTION According to this invention, the adhesive foreign material which received the load and adhered to the surface of the glass substrate and the adhesive foreign material which changed in quality with the passage of time can be removed effectively.

It is a figure which shows an example of the manufacturing process of the glass substrate of this embodiment. It is a schematic diagram of the pallet which mounts a glass substrate. It is a figure which shows an example of a washing | cleaning process. It is a schematic diagram of a single wafer cleaning system. It is the figure which showed the cloud point which changes with the density | concentration of a cleaning agent, and the density | concentration of an alkali component.

Hereinafter, the manufacturing method of the glass plate (glass substrate, sheet glass) of this invention is demonstrated in detail based on this embodiment.
The glass plate manufactured by this embodiment is a glass substrate used for the display for liquid crystal display devices, for example, thickness is 0.3-0.7 mm, and is a thin plate of the size of 2200 mm x 2500 mm (length x width). is there.

  In addition, the glass plate manufactured by this embodiment is not limited to the above, Cover glass used for the display screen of electronic devices, such as a mobile telephone, a plasma display panel, organic electroluminescence (EL), etc. It may be a plate glass used for a flat panel display (FPD).

Although the glass plate manufactured by this embodiment is not specifically limited, For example, it can be applied to the glass plate of the following composition ratios. For example, any component of Li, Na, and K is not contained, or even if at least one component of Li, Na, and K is contained, It is preferable that the total amount of the components to be contained has a glass composition that is 0.5% by mass or less. The glass composition is preferably exemplified as follows.
(A) SiO ₂ : 50 to 70% by mass,
(B) B2O _3: 5~18 wt%,
(C) Al ₂ O ₃ : 10 to 25% by mass,
(D) MgO: 0 to 10% by mass,
(E) CaO: 0 to 20% by mass,
(F) SrO: 0 to 20% by mass,
(G) BaO: 0 to 10% by mass,
(H) RO: 5 to 20% by mass (wherein R is at least one selected from Mg, Ca, Sr and Ba, and RO is the total of components contained in MgO, CaO, SrO and BaO),
(I) R ′ ₂ O: more than 0.05% by mass and 0.5% by mass or less (where R ′ is at least one selected from Li, Na and K, and R ′ ₂ O is Li ₂ O, Na ₂ O and the sum of the components contained in K ₂ O),
(J) 0.05 to 1.5% by mass in total of tin oxide and at least one metal oxide selected from iron oxide and cerium oxide.
The compositions (i) and (j) are not essential, but preferably include the compositions (i) and (j). The glass is substantially free of As ₂ O ₃ , Sb ₂ O ₃ and PbO and contains SnO ₂ .
Moreover, the glass used for the glass plate of this embodiment may be an alkali-free glass in which the content of R ′ ₂ O in (i) is substantially 0% by mass. That is, the glass used for the glass plate of the present embodiment is a glass containing a trace amount of alkali or a non-alkali glass containing the composition (i).

FIG. 1 is a flowchart showing the flow of the glass plate manufacturing method of the present embodiment.
As shown in FIG. 1, the melted glass is formed into a glass sheet which is a strip-shaped glass having a predetermined thickness by, for example, a down draw method or a float method (step S1).
Next, the formed glass sheet is scribed and cut to obtain a raw glass plate of a predetermined size (step S2). The obtained base glass is loaded on a pallet for storing and transporting the base glass as a laminated body alternately laminated with paper protecting the base glass (step S3).

  The base glass is transported to the cutting step, and the base glass is taken out from a laminate in which glass plates and paper are alternately stacked. The extracted base glass is scribed and cut to obtain a glass substrate having a product size (step S4). The obtained glass substrate is subjected to end face processing including end face grinding, polishing, and corner cutting (step S5). In the scribe, a cutting line (scribe line) which is a fine streak-like scratch is formed on the glass using a diamond cutter or the like. The glass plate including the base glass and the product size glass substrate is cut along a scribe line by a machine or a manual. Alternatively, the glass plate can be cut by scribing with laser light and thermal shock.

  Thereafter, the glass substrate is cleaned (step S6). The cleaned glass plate is optically inspected for scratches, dust, dirt, or scratches including optical defects (step S7). The glass plate having the quality matched by the inspection is loaded on the pallet and packed as a laminated body alternately laminated with paper protecting the glass plate (step S8). The packed glass plate is shipped to a supplier (step S9). Pulp paper that does not contain recycled paper is used as the paper that is sandwiched between the glass plates to be shipped to protect the surface of the glass plate from the viewpoint of preventing contamination of the surface of the glass plate.

  Note that the base glass may be transported and stored for a long period of time, for example, several weeks to several months after being loaded on the pallet (step S3) and packed (step S10). Recycled paper is used from the viewpoints of cost and environmental protection as the paper that is sandwiched between the glass plates to be stored and protects the surface of the glass plate. The base glass thus stored for a long period of time is then shipped through steps from cutting (step S4) to packaging (step S8) in the same manner as described above (step S9).

  Further, after the packaging (step S8), the glass substrate may be transported and stored for a long period of time, for example, several weeks to several months (step S10). Recycled paper is used as the paper that is sandwiched between the glass substrates to be stored and protects the surface of the glass substrate from the viewpoint of cost and environmental protection. Thus, the glass substrate stored for a long period of time is shipped (step S9) through the processes from cutting (step S4) to packing (step S8) in the same manner as the base glass.

  FIG. 2 is a diagram schematically showing a glass plate loaded on a pallet. As shown in FIG. 2, the glass sheet G including the base glass and the glass substrate is alternately stacked with the interleaving paper P in a state where the glass sheet G is leaned against the stacking portion of the pallet 100. As a result, the interleaving paper P is sandwiched between the glass plates G. In such a state, the load of the glass plate G loaded later is applied to the glass plate G previously loaded on the loading portion of the pallet 100. Therefore, the load that presses the slip sheet P against the glass plate G increases as the glass plate G is loaded first.

  When the interleaf paper P is recycled paper, adhesive foreign substances having adhesiveness derived from a resin component such as ink contained in the recycled paper may adhere to the front and back surfaces of the glass plate G in some cases. Therefore, when a load as described above is applied, as the glass plate G is loaded earlier, the adhesive foreign matter receives a larger load and tends to adhere firmly to the surface of the glass plate G. The foreign matter adhering to the glass plate G under such a load cannot be sufficiently removed by cleaning using a dilute solution obtained by diluting a conventional cleaning agent.

  In addition, when the glass plate G to which the above-mentioned adhesive foreign matter adheres is cleaned through a long-term storage (step 10) as shown in FIG. 1, the above-mentioned adhesive foreign matter changes in quality over time. However, it cannot be sufficiently removed by washing with a diluting solution obtained by diluting a conventional cleaning agent with increased tackiness or solidification.

  Glass scribing and cutting (steps S2 and S4) and glass plate G end-face processing (step S5) and other mechanical processing generate glass fragments that adhere to the surface of the glass plate G as dust. To do. Alternatively, dirt attached to a tool, jig, or the like may adhere to the surface of the glass plate G during the machining.

  The glass substrate is cleaned (S5) in order to remove dust, dirt, adhesive foreign matter, and the like attached to the surface of the glass plate G as described above. In particular, a glass substrate used for a display for a liquid crystal display device requires a high degree of cleaning because a semiconductor element is formed on the surface.

Hereinafter, the cleaning process of this embodiment will be described in more detail.
FIG. 3 is a flowchart illustrating an example of the cleaning process of the present embodiment.
First, in the step (S61) of generating a diluted solution shown in FIG. 3, a glass substrate cleaning agent is diluted with water to generate a diluted solution. As the cleaning agent for the glass substrate, an inorganic alkaline cleaning agent, for example, PK-LCG series manufactured by Parker Corporation, or semi-clean series manufactured by Yokohama Oil & Fats Co., Ltd. can be used. When these cleaning agents are used, the cleaning agent is diluted with water so as to have a concentration in the range of, for example, 1 wt% to 5 wt% to generate a diluted solution. More preferably, the cleaning solution is diluted with water so as to have a concentration in the range of 1.5 wt% or more to 4 wt% or less to generate a diluted solution.

  The water for diluting the cleaning agent may be pure water or ultrapure water that has been subjected to ion exchange treatment, EDI (Electrodeionization) treatment, filter treatment using a reverse osmosis membrane, and decarbonation treatment through a decarbonation device. It is preferable in that the surface of the glass substrate is kept clean. In order to remove the soluble foreign matter, it is preferable to pass activated carbon. Specifically, foreign substances such as fine particles are removed from the water using a filter, and after this, the activated carbon is permeated to remove organic matter, followed by ion exchange treatment, EDI (Electrodeionization) treatment, filter treatment with a reverse osmosis membrane, And it is preferable to perform a decarbonation treatment through a decarbonation device.

  In the ion exchange treatment, ionic substances contained in water, such as chlorine ions and sodium ions, are removed from the water using an ion exchange resin membrane. In the EDI treatment, an ionic substance is removed from water with higher accuracy by using an ion exchange resin membrane and utilizing a potential gradient formed by applying a potential to the electrode. Furthermore, in the filter process using a reverse osmosis membrane (RO membrane), ionic substances, salts, or organic substances are removed from water. Further, in the carbon dioxide removal treatment, carbon dioxide is removed from the water using a carbon dioxide removal device.

The concentration of the alkali component in the diluted solution generated by diluting the cleaning agent with water as described above is, for example, about 0.02 wt% to 0.15 wt% in terms of the concentration of potassium hydroxide (KOH). .
As shown in FIG. 3, in this embodiment, the diluted solution includes one or more selected from KOH, NaOH, ETDA-4Na, ETDA-4K, Na ₄ P ₂ O ₇ , and K ₄ P ₂ O ₇ . An alkaline component is added so that the total concentration is 1.0 wt% or more and 4 wt% or less to generate a cleaning liquid (S62). The above alkali component has higher etching properties of glass and excellent solubility than other alkali components. In particular, it is preferable to use KOH alone as the alkali component from the viewpoints of etching property and solubility and preventing adverse effects on the thin film transistor formed on the glass substrate. KOH and NaOH are advantageous in terms of wastewater treatment as compared with other alkali components.

  In the present embodiment, a diluent obtained by diluting the cleaning agent with water is clearly distinguished from a cleaning solution obtained by adding the alkali component to the diluted solution. The addition of the alkali component to the diluent can be performed simultaneously with or in parallel with the dilution of the cleaning agent with water.

  The total concentration of the alkali components in the cleaning liquid of the present embodiment is preferably as high as possible in terms of cleaning power for removing the sticking foreign matter. However, if the concentration of the alkali component becomes too high, detergent residue remaining on the surface of the glass substrate increases, so that the cleaning performance of the glass substrate is reduced, the apparatus is corroded, and crystals are generated in the cleaning liquid. There are problems such as.

  In the present embodiment, a cleaning solution obtained by adding the alkali component to a diluted solution obtained by diluting a cleaning agent with water is indicated by a cloud point. Here, the cloud point is an index uniquely determined by the concentration of the cleaning agent and the concentration of the alkali component. Phase separation occurs due to a temperature change of the cleaning solution, and the cleaning agent dissolved in the cleaning solution, a part of the alkaline component Is the temperature at which precipitation begins. When an alkaline component such as KOH is added to the cleaning agent, the hydrogen bond between the surfactant and water is broken, and the water solubility rapidly decreases, so that the cleaning agent becomes opaque. This opaque temperature is the cloud point. If a cleaning solution having a cloud point or higher is used for cleaning the glass substrate, the deposited cleaning agent and alkali component may adhere to the glass substrate. In the cleaning of the glass substrate (S5), even if the cleaning liquid can remove dust, dirt, sticking foreign matters, etc. attached to the surface of the glass substrate, the cleaning agent and alkali components remain on the surface of the glass substrate. If so, there arises a problem that the cleaning property of the glass substrate surface cannot be ensured due to the cleaning agent and the alkali component remaining on the surface of the glass substrate. For this reason, it is necessary to clean the glass substrate using a cleaning liquid that can remove dust, dirt, adhesive foreign matter, and the like attached to the surface of the glass substrate and does not leave a cleaning agent or an alkali component. By removing dust, dirt, adhesive foreign matter, and the like and leaving no cleaning agent or alkali component, it is possible to realize the cleaning performance of the glass substrate surface.

  In the cleaning liquid of this embodiment, the concentration of the cleaning agent and the concentration of the alkali component are set so that the cloud point is 60 ° C. or higher. As described above, the concentration of the cleaning agent is set to a concentration in the range of 1.5 wt% to 4 wt%. When the concentration of the cleaning agent exceeds 4 wt%, the detergent residue remaining on the surface of the glass substrate increases when the glass substrate is cleaned using this cleaning agent, so that the cleanliness of the glass substrate is lowered. Therefore, the concentration of the cleaning agent is determined so that the concentration of the cleaning agent is 4 wt% or less. On the other hand, when the concentration of the cleaning agent is less than 1.5 wt%, dust, dirt, adhesive foreign matters, etc. attached to the surface of the glass substrate cannot be removed when the glass substrate is cleaned using this cleaning agent. For this reason, the concentration of the cleaning agent is determined so that the concentration of the cleaning agent is 1.5 wt% or more.

  As described above, the concentration of the alkali component in the cleaning liquid is set to a concentration ranging from 1.0 wt% to 4 wt% at which the cloud point is 60 ° C. or higher. Here, the alkali component is preferably KOH as the alkali component from the viewpoints of etching property and solubility and preventing adverse effects on the thin film transistor formed on the glass substrate. When the cloud point is less than 60 ° C., when the glass substrate is washed with this cleaning agent, the organic matter derived from the alkali component remaining on the surface of the glass substrate is increased, so that the cleanliness of the glass substrate is lowered. For this reason, the density | concentration of the alkali component which a cloud point becomes 60 degreeC or more is defined. On the other hand, when the concentration of the alkali component is less than 1.0 wt%, when the glass substrate is cleaned with this cleaning agent, dust, dirt, sticking foreign matters and the like attached to the surface of the glass substrate cannot be removed. For this reason, the concentration of the alkali component is determined so that the concentration of the alkali component is 1.0 wt% or more.

  A cleaning liquid of this embodiment is generated by adding KOH to a cleaning agent having a concentration in the range of 1.5 wt% or more and 4 wt% or less so that the cloud point of the cleaning liquid is 60% or more. Use the PK-LCG series manufactured by Parker Corporation or the semi-clean series manufactured by Yokohama Oil & Fats Co., Ltd. as a cleaning agent so that the concentration of this cleaning agent is in the range of 1.5 wt% to 4 wt%. The cleaning liquid of this embodiment having a cloud point of 60% or more can be generated by adding KOH having a concentration in the range of 1.0 wt% to 4 wt% to the diluted cleaning agent. .

  The cleaning liquid generated as described above is used in single wafer cleaning and batch cleaning of the glass plate G including brush cleaning (S63) and sponge cleaning (S64) shown in FIG. Hereinafter, a method of using the cleaning liquid of this embodiment for single wafer cleaning will be described, but it can also be used for batch cleaning.

Hereinafter, a cleaning system used for single wafer cleaning will be described.
4 (a) and 4 (b) are diagrams showing an outline of a single wafer cleaning system 10 for performing wafer cleaning, FIG. 4 (a) is a plan view, and FIG. 4 (b) It is a side view. 4 (a) and 4 (b), the illustration of the conveying device that conveys the glass plate G is omitted.

  As shown in FIG. 4A, the single wafer cleaning system 10 includes a brush unit 12, a sponge unit 14, and a shower unit 16. These devices are arranged in this order from the upstream side in the conveyance direction of the glass plate G. The single wafer cleaning system 10 includes a cleaning liquid tank 18 and a pure water tank 20 as shown in FIG.

  The cleaning liquid tank 18 stores the above-described cleaning liquid generated by adding KOH at a predetermined concentration to the diluent for the glass substrate cleaning agent while keeping the temperature at a predetermined temperature. In this embodiment, the cleaning liquid tank 18 is provided with temperature adjusting means such as a heater for adjusting the temperature of the cleaning liquid, and the cleaning liquid is heated to a constant temperature in the range of 60 ° C. to 80 ° C. and kept warm. More preferably, the cleaning solution is kept at a temperature in the range of 60 ° C to 75 ° C.

  The nozzles 18 a and 18 b are provided so as to spray and supply the cleaning liquid supplied from the cleaning liquid tank 18 to the front and back surfaces of the glass plate G in the brush unit 12. The nozzles 18 c and 18 d are provided so as to spray and supply the cleaning liquid supplied from the cleaning liquid tank 18 to the front and back surfaces of the glass plate G in the sponge unit 14.

The pure water tank 20 stores the pure water or ultrapure water generated as described above.
The nozzles 20 a and 20 b are provided so as to inject pure water or ultrapure water supplied from the pure water tank 20 onto the front and back surfaces of the glass plate G in the shower unit 16.

  The brush unit 12 includes cleaning brush rows 12a and 12b.

  The cleaning brush rows 12a and 12b are arranged at different positions in the conveying direction of the glass plate G, that is, at an upstream position and a downstream position. The cleaning brush rows 12a and 12b are arranged so that the front and back surfaces of the glass plate G can be cleaned up and down, and are provided so as to clean the glass plate G with the glass plate G interposed therebetween.

  The cleaning brush rows 12a and 12b are each provided with a plurality of cleaning brushes in a direction crossing the conveying direction of the glass plate G. The brush unit 12 cleans the front and back surfaces of the glass plate G by rotating the cleaning brush. In the illustrated example, the cleaning brush rows 12a and 12b are provided in two rows, but three or more rows may be provided, or only one row may be provided.

  The sponge unit 14 includes cleaning sponge rows 14a and 14b.

  The cleaning sponge rows 14a and 14b are arranged at different positions in the conveying direction of the glass plate G, that is, at an upstream position and a downstream position. The cleaning sponge rows 14a and 14b are arranged so that the front and back surfaces of the glass plate G can be cleaned up and down, and are provided with the glass plate G sandwiched between them.

  The cleaning sponge rows 14a and 14b are each provided with a plurality of cleaning sponges in a direction crossing the conveying direction of the glass plate G. The sponge unit 14 cleans the front and back surfaces of the glass plate G by rotating the cleaning sponge. In the illustrated example, the cleaning sponge rows 14a and 14b are provided in two rows, but three or more rows may be provided, or only one row may be provided.

Next, the flow of cleaning the glass plate G in the single wafer cleaning system 10 will be described.
In the cleaning liquid tank 18, the cleaning liquid is kept at a predetermined temperature in the range of 60 ° C. to 80 ° C., more preferably 60 ° C. to 75 ° C., by temperature adjusting means such as a heater.

In the brush unit 12, brush cleaning (S63) shown in FIG. 3 is performed.
The cleaning liquid supplied from the cleaning liquid tank 18 is sprayed from the nozzles 18a and 18c, and is supplied to the front and back surfaces of the glass plate G transferred into the brush unit 12 by the transfer device. The cleaning liquid supplied to the front and back surfaces of the glass plate G is heated to a predetermined temperature in the range of 60 ° C. to 75 ° C., more preferably 65 ° C. to 75 ° C., for example.

  In the brush unit 12, the front and back surfaces of the glass plate G have a predetermined temperature in the range of 60 ° C. to 75 ° C., more preferably 65 ° C. to 75 ° C. It is cleaned by a plurality of cleaning brushes 12b. Thereafter, the glass plate G is transported to the sponge unit 14 by the transport device.

In the sponge unit 14, the sponge cleaning (S64) shown in FIG. 3 is performed.
The cleaning liquid supplied from the cleaning liquid tank 18 is sprayed from the nozzles 18c and 18d, and is supplied to the front and back surfaces of the glass plate G transferred into the sponge unit 14 by the transfer device. The cleaning liquid supplied to the front and back surfaces of the glass plate G is heated to a predetermined temperature in the range of 60 ° C. to 75 ° C., more preferably 65 ° C. to 75 ° C., for example.

  In the sponge unit 14, the front and back surfaces of the glass plate G have a predetermined temperature of 60 ° C. to 75 ° C., more preferably 65 ° C. to 75 ° C., and the front and back surfaces of the cleaning sponge rows 14a and 14b are present. It is cleaned by a plurality of cleaning sponges. Thereafter, the glass plate G is transported to the shower unit 16 by a transport device.

  Pure water or ultrapure water supplied from the pure water tank 20 is sprayed from the nozzles 20a and 20b, and supplied to the front and back surfaces of the glass plate G transferred into the shower unit 16 by the transfer device. Thereby, the glass plate G is rinsed with pure water or ultrapure water, and the components of the cleaning liquid are washed away.

The glass plate G carried out from the shower unit 16 is sent to a batch cleaning system that performs batch cleaning (S65) shown in FIG. In the batch cleaning (S65), a plurality of glass plates G are accommodated in a cassette, and are sequentially immersed and cleaned in a plurality of liquid tanks.
Depending on the configuration of the single wafer cleaning system 10, batch cleaning (S65) may not be performed. In that case, the glass plate G is dried through an air knife or a heat drying step, and sent to the inspection (S7) shown in FIG.

Next, the effect | action of the washing | cleaning method of the glass plate G of this embodiment is demonstrated.
In this embodiment, as described above, an alkaline component such as KOH is added to a diluted solution having a concentration range of 1.5 wt% or more and 4 wt% or less generated by diluting the cleaning agent with water to generate a cleaning solution. In this way, a cleaning liquid having a cloud point of 60 ° C. or higher can be obtained by adding an alkaline component such as KOH at a concentration of 0.4 wt% or higher to the diluted diluent of the cleaning agent to produce a cleaning liquid.

  In this embodiment, the glass plate G is cleaned using a cleaning solution having a total concentration of alkali components such as KOH of 1.0 wt% to 4 wt% and a cleaning solution having a cloud point of 60 ° C. or higher. The concentration of alkali components such as KOH has a cloud point of 60 ° C. or higher, and it is possible to remove adhesive foreign substances derived from recycled paper attached to the surface of the glass plate G regardless of the order in which the glass plates G are loaded on the pallet. become. That is, according to the cleaning liquid of the present embodiment, the effect of removing foreign substances including adhesive foreign matter, glass pieces, and dust that are attached to the surface of the glass plate G under load can be obtained. Moreover, since the precipitation of the surfactant dissolved in the cleaning liquid is limited by using a cleaning liquid having a cloud point of 60 ° C. or higher in a temperature range of 60 ° C. to 75 ° C., an organic residue based on the surfactant Is suppressed, and the glass plate G surface is rinsed with pure water, thereby ensuring the cleanability of the glass plate G surface.

  As described above, the cleaning liquid in which an alkaline component such as KOH is added to the cleaning liquid diluted so as to have a cloud point of 60 ° C. or more has a higher etching property of the glass plate G by the cleaning liquid than the conventional cleaning liquid dilution. In addition to the foreign matter including glass pieces and dust, the adhesive foreign matter attached to the surface of the glass plate G under the load can be removed from the surface of the glass plate G to be removed. . Moreover, the residue of the organic substance based on a cleaning agent etc. is suppressed by using the washing | cleaning liquid which has a cloud point at the temperature of a cloud point vicinity, and the washability of the surface of the glass plate G can be ensured.

  In addition, the surface tension of the cleaning liquid obtained by adding an alkaline component such as KOH to the cleaning liquid is lower than that of the conventional liquid. That is, by adding an alkaline component such as KOH to a diluent containing a surfactant, the surface tension of the cleaning agent is hardly obtained when an alkaline component such as KOH is added to pure water alone. The effect of reducing can be acquired. This makes it easier for the cleaning agent to penetrate between the adhesive foreign material and the glass plate than before, and the synergistic effect of improving the etching property of the glass plate G by the cleaning agent results in glass containing adhesive foreign material, glass pieces, and dust. Foreign matter adhering to the plate G is removed more effectively.

  Furthermore, by increasing the concentration of alkaline components such as KOH added to the diluent of the cleaning agent, it is possible to remove sticking foreign substances attached to the surface of the glass plate stored over a long period of several weeks to several months. Increases effectiveness. For example, by using a cleaning solution in which an alkaline component such as KOH is added to a diluted solution obtained by diluting the cleaning agent with pure water to 1.5 wt% to 4 wt% at a concentration at which the cloud point becomes 60 ° C or higher, The effect of removing the adhesive foreign matter derived from recycled paper which has been changed in quality and increased in curing or tackiness by the above synergistic effect becomes more remarkable.

  The higher the concentration of alkaline components such as KOH in the cleaning liquid, the better the effect of removing adhesive foreign matter, but the viewpoint of suppressing organic residue derived from the cleaning liquid and the burden on the cleaning device are reduced. From the viewpoint of preventing crystallization of components and facilitating handling of the cleaning liquid, the concentration of alkali components such as KOH in the cleaning agent is preferably 1 wt% or more and 4 wt% or less in total, and from 1.5 wt% or more More preferably, it is 4 wt% or less. By setting the concentration of the alkali component to 1 wt% or more to 4 wt% or less, the cloud point of the cleaning liquid becomes 60 ° C. or higher, and even if the cleaning liquid is used in a temperature range of 60 ° C. to 75 ° C. where the effect of the cleaning liquid is easily obtained, Since precipitation of the surfactant dissolved in the cleaning liquid can be suppressed, organic residue based on the surfactant can be suppressed.

  Moreover, by using the temperature of the cleaning liquid in the range of, for example, 60 ° C. to 75 ° C., more preferably 65 ° C. to 75 ° C., at least one of the single wafer cleaning and the batch cleaning, the adhesive foreign matter can be softened and expanded. Due to the synergistic effect of the softening and expansion effects of the adhesive foreign matter and the effect of adding an alkaline component such as KOH to the diluent, the adhesive foreign matter attached to the front and rear surfaces of the glass plate G and subjected to a load The deteriorated adhesive foreign matter can be removed more effectively. Moreover, even when a cleaning liquid having a cloud point of 60 ° C. or higher is used in a temperature range of 60 ° C. or higher to 75 ° C. or lower, the phase separation of the cleaning liquid is limited, and there are few residues of cleaning agents and alkaline components Since the residue can be removed by washing with pure water or the like, the surface of the glass plate G can be cleaned.

  As explained above, according to the cleaning liquid of this embodiment and the glass plate G cleaning method using the cleaning liquid, not only the effect of removing various foreign substances attached to the glass plate G is improved, but also the load is received. Thus, the adhesive foreign matter derived from recycled paper adhering to the surface of the glass plate G and the adhesive foreign matter that has changed in quality over time can be effectively removed from the front and back surfaces of the glass plate G. Moreover, since the residue of the cleaning agent after cleaning is suppressed, the cleaning property of the surface of the glass plate G can be realized.

Example 1
The cloud point of the cleaning liquid was measured by changing the concentration of the cleaning agent and the concentration of the alkali component. Semi-clean KG, an inorganic alkaline cleaner manufactured by Yokohama Oil & Fats Co., Ltd. as a cleaning agent, KOH as an alkaline component, semi-clean KG is diluted with pure water to obtain a diluted solution, and KOH is added to the diluted solution. Thus, a cleaning liquid was obtained. FIG. 5 is a diagram showing the cloud point that varies depending on the concentration of the cleaning agent and the concentration of the alkali component. By changing the concentration of the cleaning agent KG and the concentration of the alkaline component KOH, the cloud point of the cleaning liquid changes as shown in the figure, and the cloud point varies depending on the concentration of the cleaning agent and the concentration of the alkaline component. Was determined uniquely. By using the cleaning liquid in a temperature range where the cloud point is uniquely determined, phase separation of the cleaning liquid can be prevented, and organic residue derived from the cleaning liquid can be suppressed.

(Example 2)
Hereinafter, examples to which the present invention is applied and comparative examples to which the present invention is not applied will be described.
In this example, after cleaning the glass plate, the number of deposits adhered to the surface of the glass plate was measured, and the cleaning power was compared. Hereinafter, a specific procedure will be described.

Sample used for particle removal evaluation (1) Detergent: Semi-clean KG, an inorganic alkaline detergent manufactured by Yokohama Oil & Fat Co., Ltd.
(2) Alkali component: KOH
(3) Glass plate: non-alkali glass (4) Deposit: CeO ₂ for polishing particle size 1 μm to 4 μm
In all Examples and Comparative Examples, semi-clean KG was diluted with pure water to obtain a diluted solution, and KOH was added to the diluted solution to obtain a cleaning solution.
Sample used for evaluation of removal of adhesive foreign matter (1) Cleaning agent: Semi-clean KG, an inorganic alkaline cleaning agent manufactured by Yokohama Oil & Fat Co., Ltd.
(2) Alkali component: KOH
(3) Glass plate: Alkali-free glass (4) Deposit: Polyvinyl chloride (PVC) gloves In all examples and comparative examples, dilute semi-clean KG with pure water to obtain a diluted solution. A cleaning solution was obtained by adding KOH.

First, in one sample, polishing CeO ₂ is dispersed in pure water to form a slurry, and the slurry-like CeO ₂ is rubbed against a clean glass plate. The surface of the glass plate G on which the slurry-like CeO ₂ is rubbed is washed with pure water, and excess CeO ₂ is removed. The slurry-like CeO ₂ corresponds to particles adhering to the glass plate G when the glass plates G shown in FIG. 2 are alternately laminated with the interleaf paper P and the interleaf paper P is pressed against the glass plate G. Another sample was a clean glass plate with PVC glove marks used in a clean room and baked in a clean oven at 170 ° C. for 60 seconds. The PVC glove mark adhering to the glass plate corresponds to an adhesive foreign matter derived from a resin component such as ink contained in the interleaf paper P. The glass plate G was sponge-cleaned using cleaning solutions having different cleaning agent concentrations, alkali component (KOH) concentrations, cleaning solution temperatures, and cloud points, as shown in Tables 1 and 2 below. After the sponge was washed, the glass plate G was washed with pure water and then dried. Then, the number of particles adhering to the surface of the glass plate G that had been cleaned and dried was measured with an optical automatic inspection device. Further, the amount of organic matter remaining on the surface of the glass plate G after washing the particle evaluation sample was measured by gas chromatography / mass spectrometry (GC-MS). The adhesive foreign material sample was visually confirmed using a condenser. Here, the particles shown in Tables 1 and 2 are attached substances such as CeO ₂ , glass pieces, dust, and dirt, the organic substances are attached substances of interleaf paper P component and detergent residue, and the adhesive foreign matter is PVC. It is a deposit.

However,
Particle removal state ○ = 98% or more, Δ = 95% or more and less than 98%, × = less than 95%.
Organic residue state (residue per 1 cm ² ) A = 0.05 ng or more and less than 0.10 ng, ◯ = 0.10 ng or more and less than 0.25 ng, Δ = 0.25 ng or more and less than 0.50 ng, x = 0.50 ng or more.
Adhesive foreign matter removal state ○ = No residue, Δ = Slight residue, × = Many residues.

  The cleaning liquids shown in Examples 1 to 6 in Table 1 have a concentration of the cleaning agent in the range of 1.5 wt% to 4 wt%, have a cloud point of 60 ° C. or higher, and soften and expand the adhesive foreign matter attached to the glass plate. By using the cleaning liquid at a cleaning liquid temperature range of 60 ° C. to 75 ° C., it was possible to remove the sticking foreign matter. In addition, by using a cleaning solution having a cloud point of 60 ° C. or higher in the temperature range from 60 ° C. to 75 ° C. near the cloud point, the phase separation of the cleaning solution is suppressed, so the organic residue should be less than 0.50 ng. I was able to. Further, the particle removal state was 95% or more. It was confirmed that the cleaning liquids shown in Examples 1 to 6 in Table 1 were able to remove the sticking foreign matter and further suppress the organic residue while removing the particles. From the above, the cleaning liquid having a cleaning agent concentration of 1.5 wt% to 4 wt%, containing an alkaline component of KOH, and having a cloud point of 60 ° C. or higher can remove adhesive foreign matter, and further remove particles. However, since organic residue can be suppressed, it was confirmed that it is suitable for cleaning a glass substrate for liquid crystal.

  The cleaning liquid shown in Comparative Examples 1 to 6 in Table 2 has a cloud point of less than 60 ° C., and the cleaning liquid can be softened and expanded in the temperature range of 60 ° C. to 70 ° C. When used, phase separation of the cleaning liquid occurs. For this reason, even after washing, it was confirmed that the organic residue was 0.50 ng or more. Further, in the cleaning liquid having a cloud point of less than 60 ° C., the particle removal state was less than 95%, and the adhesive foreign matter could not be completely removed. For this reason, it has been confirmed that the cleaning liquid having a cloud point of less than 60 ° C. is not suitable for cleaning the glass substrate for liquid crystal because it cannot remove the sticking foreign matters and particles and also has organic residue.

  As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to said embodiment. Additions, omissions, substitutions, and other modifications can be made without departing from the spirit of the present invention. For example, in the above-described embodiment, the glass plate for FPD has been described as the glass plate, but the present invention is not limited to the glass plate for FPD.

10 single wafer cleaning system 12 brush unit 12a, 12b cleaning brush row 14 sponge unit 14a, 14b cleaning sponge row 16 shower unit 18 cleaning liquid tank 18a, 18b, 18c, 18d nozzle 20 pure water tank 20a, 20b nozzle 100 pallet G glass plate P slip

Claims (6)

A diluted solution obtained by diluting the cleaning agent with water having a concentration of 1.5% to 4%, KOH, NaOH, ETDA-4Na, ETDA-4K, Na ₄ P ₂ O ₇ , K ₄ P ₂ O ₇ The alkali component was added to the diluent so that the total concentration of one or more alkali components selected from 1 to 4% was obtained.
A cleaning liquid for a glass substrate for liquid crystal. A cleaning liquid having a cloud point determined by the concentration of the cleaning agent and the concentration of the alkali component,
The concentration of the cleaning agent is 1.5% to 4%,
The alkaline component comprises one or more alkaline components selected from KOH, NaOH, ETDA-4Na, ETDA-4K, Na ₄ P ₂ O ₇ , K ₄ P ₂ O ₇ ,
The cloud point is 60 ° C. or higher.
A cleaning liquid for a glass substrate for liquid crystal. The alkaline component is KOH;
The concentration of the KOH is 1% to 4%.
A cleaning liquid for a glass substrate for liquid crystal according to claim 1 or 2. The cleaning agent includes a surfactant and is composed of an inorganic alkaline cleaning agent having a cloud point.
The cleaning liquid for glass substrates for liquid crystals according to any one of claims 1 to 3. A method for cleaning a glass substrate for liquid crystal, comprising a cleaning step of removing foreign matter adhering to the glass substrate using the liquid crystal glass substrate cleaning liquid according to any one of claims 1 to 4,
Prior to the cleaning step, the glass substrate is laminated with recycled paper sandwiched therebetween,
The foreign matter is an adhesive foreign matter derived from a substance contained in the recycled paper.
A method for cleaning a glass substrate for liquid crystal. In the cleaning step, the temperature of the cleaning liquid is set higher than 60 ° C.,
The method for cleaning a glass substrate for liquid crystal according to claim 5.

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