JP6498947B2 - Manufacturing method of glass substrate - Google Patents

Description

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

  A glass substrate used for manufacturing a flat panel display (FPD) such as a liquid crystal display and a plasma display is manufactured by, for example, an overflow down draw method. In the overflow down-draw method, the molten glass that has flowed into the groove on the upper surface of the molded body flows down on both sides of the molded body and joins at the lower end of the molded body, so that the glass ribbon is continuously formed. Molded. The formed glass ribbon is cooled while being drawn downward, and then cut to obtain a glass substrate having a predetermined size. The obtained glass substrate is packed and shipped through an end face processing step, a surface cleaning step, an inspection step, and the like.

  In the step of cutting the glass ribbon into a glass substrate having a predetermined dimension, a cutting method using a cutter or a laser is generally used. In the cutting method using a cutter, a glass ribbon is mechanically cut and cut. Therefore, a crack having a depth of about several μm to 100 μm is formed on the cut surface of the glass substrate. This crack causes deterioration of the mechanical strength of the glass substrate. In the laser cutting method, the glass ribbon is cut by using thermal stress. Therefore, the cut surface of the glass substrate becomes sharp and easily chipped. These cracks and sharp parts need to be removed by grinding and polishing. That is, in order to increase the mechanical strength of the glass substrate, suppress the occurrence of defects in the glass substrate, and facilitate handling in a subsequent process, an end face processing step of the glass substrate is performed.

  In the end face machining step, a chamfering process for chamfering the corners of the end face is performed using a grindstone. Since the cooling performance used in the chamfering process is higher than that of pure water, the use of an aqueous solution containing a nonionic surfactant as an organic substance has been studied (for example, Patent Document 1). An aqueous solution containing a nonionic surfactant has a low contact resistance with a grindstone, suppresses a grinding resistance during polishing, and has a good grinding efficiency. However, when an aqueous solution containing a nonionic surfactant is used as a cooling liquid, it is required to be recovered and reused for the purpose of reducing the load on the environment.

JP2011-63466A

When the coolant is supplied to the grindstone, moisture is evaporated by the heat generated by grinding, and the nonionic surfactant concentration increases. In addition, in order to prevent the cooling liquid containing glass particles generated by grinding of the glass end surface from scattering and the glass particles from adhering to the glass surface, a shower may be applied from the top to the glass substrate surface. When this shower water is mixed into the recovered coolant, the concentration of the nonionic surfactant in the coolant decreases. For these reasons, the concentration of the recovered coolant is not constant. When such a coolant is circulated and used, the cooling capacity is not constant and the life of the grindstone is shortened.
Patent Document 1 discloses a processing liquid containing a nonionic surfactant for the purpose of obtaining rust prevention properties, and solves the above-described problems that occur when the concentration of the cooling liquid is not constant. It is not a thing.

  The objective of this invention provides the manufacturing method of the glass substrate which cools a grindstone stably and prolongs a lifetime of a grindstone.

One aspect of the present invention is a glass substrate manufacturing method including an end face processing step of processing an end face of the glass substrate with the grindstone while supplying a cooling liquid to a contact portion between the grindstone and the glass end face. in the process step, the contact portion by supplying the cooling liquid is an aqueous solution containing a nonionic surfactant, a cooling step of cooling the contact portion, the concentration of the nonionic surfactant of the cooling liquid and the measurement result is compared with the concentration as a reference, when the concentration becomes the reference and the measurement results are different, the so that the concentration of the nonionic surfactant is the concentration to be the reference non-ionic A control step for managing the concentration of the non-ionic surfactant, and the concentration of the non-ionic surfactant is a correspondence relationship between the concentration of the non-ionic surfactant prepared in advance and the refractive index of the coolant See before Determined from the measured values of the refractive index of the cooling liquid.

Furthermore, it comprises a circulation step of circulating the coolant that has undergone the control step ,
Measuring the electrical conductivity of the circulating coolant, and when the measurement result of the electrical conductivity is equal to or higher than a preset value, the step of replacing the coolant with another coolant , It is preferable.
Moreover, it is preferable that pH of the said cooling fluid is 8-11.

Furthermore, it is preferable to provide the supply process which supplies water to the said glass substrate surface during supplying the said cooling fluid to the said contact part .

  The glass substrate is preferably a glass substrate for a color filter.

  The glass substrate is preferably a glass substrate for a flat panel display.

  The manufacturing method of the glass substrate which concerns on this invention can cool a grindstone stably, and can prolong the life of a grindstone.

It is a flowchart of a glass substrate manufacturing process. It is a figure which shows an example of an end surface processing apparatus. It is a figure which shows an example of an end surface grinding apparatus.

Hereinafter, the manufacturing method of the glass substrate of this invention is demonstrated based on embodiment.
(1) Manufacturing process of glass substrate First, the manufacturing process of the glass substrate 10 processed with an end surface processing apparatus is demonstrated. A glass substrate is used for manufacturing flat panel displays (FPD) such as liquid crystal displays, plasma displays, and organic EL displays. The glass substrate includes not only a flat glass substrate but also a curved glass substrate. The glass substrate has, for example, a thickness of 0.2 mm to 0.8 mm, and dimensions of 680 mm to 2200 mm in length and 880 mm to 2500 mm in width.

An example of the glass substrate is a glass substrate that is a boroaluminosilicate glass having the following compositions (a) to (j).
(A) SiO ₂ : 50% by mass to 70% by mass,
(B) Al ₂ O ₃ : 10% by mass to 25% by mass,
(C) B ₂ O ₃ : 1% by mass to 18% by mass,
(D) MgO: 0% by mass to 10% by mass,
(E) CaO: 0% by mass to 20% by mass,
(F) SrO: 0% by mass to 20% by mass,
(G) BaO: 0% by mass to 10% by mass,
(H) RO: 5% by mass to 20% by mass (R is at least one selected from Mg, Ca, Sr and Ba),
(I) R ′ ₂ O: 0% by mass to 2.0% by mass (R ′ is at least one selected from Li, Na and K),
(J) At least one metal oxide selected from SnO ₂ , Fe ₂ O ₃ and CeO ₂ .
The glass having the above composition is allowed to contain other trace components in the range of less than 0.1% by mass.

FIG. 1 is an example of a flowchart showing a glass substrate manufacturing process. The glass substrate manufacturing process mainly includes a forming process (step S1), a plate-making process (step S2), a cutting process (step S3), a roughening process (step S4), and an end face processing process (step S5). ), A cleaning process (step S6), an inspection process (step S7), and a packing process (step S8).
In the forming step S1, a glass ribbon is continuously formed from a molten glass obtained by heating a glass raw material by an overflow down draw method or a float method. The molded glass ribbon is cooled to a glass annealing point or lower while the temperature is controlled so that distortion and warpage do not occur.
In the plate-drawing step S2, the glass ribbon formed in the forming step S1 is cut to obtain a base plate glass having a predetermined dimension.
In the cutting step S3, the base glass obtained in the plate-drawing step S2 is cut to obtain a product-sized glass substrate.
In the roughening step S4, a roughening treatment is performed to increase the surface roughness of the glass substrate obtained in the cutting step S3. The roughening process of the glass substrate is, for example, a wet etching process using an etchant containing hydrogen fluoride.

In the end face processing step S5, chamfering and polishing of the end face of the glass substrate that has been subjected to the roughening process in the roughening step S4 are performed. The end face processing step S5 is performed by an end face processing apparatus described later. The chamfering process of the end face is a process of grinding a corner portion between the pair of main surfaces and the end face of the glass substrate into an R shape. The end face polishing process is a process for reducing (smoothing) the surface roughness of the chamfered end face.
In the cleaning step S6, the glass substrate that has been subjected to the end surface processing in the end surface processing step S5 is cleaned. On the glass substrate, foreign matter such as minute glass pieces generated in the cutting step S3 and the end face processing step S5 and organic substances existing in the atmosphere is attached. These foreign substances are removed by cleaning the glass substrate.
In the inspection step S7, the glass substrate cleaned in the cleaning step S6 is inspected. Specifically, the shape of the glass substrate is measured, and the defect of the glass substrate is optically detected. The defects of the glass substrate are, for example, scratches and cracks existing on the surface of the glass substrate, foreign matters adhering to the surface of the glass substrate, and fine bubbles existing inside the glass substrate.
In packing process S8, the glass substrate which passed the test | inspection in test process S7 is laminated | stacked and packed on a pallet alternately with the slip sheet for protecting a glass substrate. The packed glass substrate is shipped to an FPD manufacturer or the like.

(2) End surface processing step Next, an end surface processing step S5 in which the end surface processing apparatus chamfers and polishes the end surface of the glass substrate will be described with reference to FIG. FIG. 2 is a diagram for explaining an end surface processing step S5 performed by the end surface processing apparatus 100. FIG. The glass substrate 10 is conveyed along a predetermined path in the end face processing apparatus 100 in a state where the main surface is parallel to the horizontal plane.

The glass substrate 10 processed by the end surface processing apparatus 100 has a rectangular shape. The glass substrate 10 has a pair of first end surfaces 11a and 11b and a pair of second end surfaces 12a and 12b. The first end faces 11 a and 11 b are end faces parallel to the short side of the glass substrate 10. The second end faces 12 a and 12 b are end faces parallel to the long side of the glass substrate 10.
The end face processing apparatus 100 mainly includes a first chamfering apparatus 101, a rotating apparatus 102, a second chamfering apparatus 103, and a corner cutting apparatus 104. The respective devices are arranged in this order from the upstream side to the downstream side of the conveyance path of the glass substrate 10, and the glass substrate 10 passes in this order.

First, the 1st chamfering processing apparatus 101 chamfers the corner | angular part of 1st end surface 11a, 11b of the glass substrate 10 using a pair of 1st diamond wheel 111 installed in the both sides of the conveyance path | route of the glass substrate 10. FIG. . Then, the 1st chamfering apparatus 101 grind | polishes the 1st end surfaces 11a and 11b of the glass substrate 10 using a pair of 1st grinding | polishing wheel 121 installed in the both sides of the conveyance path | route of the glass substrate 10. FIG. Thereafter, the glass substrate 10 is conveyed to the rotating device 102.
Next, the rotating device 102 rotates the glass substrate 10 by 90 ° in a horizontal plane. Thereafter, the glass substrate 10 is conveyed to the second chamfering apparatus 103.
Next, the second chamfering apparatus 103 chamfers the corners of the second end surfaces 12 a and 12 b of the glass substrate 10 using a pair of second diamond wheels 112 installed on both sides of the conveyance path of the glass substrate 10. . Then, the 2nd chamfering processing apparatus 103 grind | polishes the 2nd end surfaces 12a and 12b of the glass substrate 10 using a pair of 2nd grinding | polishing wheel 122 installed in the both sides of the conveyance path | route of the glass substrate 10. FIG. Thereafter, the glass substrate 10 is conveyed to the corner cutting device 104.

  Next, the corner cutting device 104 chamfers four corners of the main surface of the glass substrate 10 using the four third diamond wheels 113. Thereafter, the glass substrate 10 is transported to the cleaning step S6.

For the first diamond wheel 111, the second diamond wheel 112, and the third diamond wheel 113, for example, diamond abrasive grains having a particle size of # 400 are hardened with a metallic binder containing iron. The first diamond wheel 111, the second diamond wheel 112, and the third diamond wheel 113 may be the same type of wheel.
For the first polishing wheel 121 and the second polishing wheel 122, for example, silicon carbide abrasive grains having a particle size of # 400 are hardened with a metallic binder containing iron. The first grinding wheel 121 and the second grinding wheel 122 may be the same type of wheel. The binder may be a cobalt-based or copper-based bond material or a resin-based bond material.

Here, the embodiment of the present invention includes the following steps when grinding each end surface in the end surface processing step.
(I) a cooling step of cooling the contact portion by supplying a coolant that is an aqueous solution containing a nonionic surfactant to the contact portion between the grindstone and the glass substrate end surface;
(Ii) The concentration of the nonionic surfactant in the cooling liquid is measured, the reference concentration and the measured value are compared, and when the reference concentration and the measured value are different, the reference concentration is obtained. A control process for managing the concentration of the nonionic surfactant in the coolant.

Furthermore, you may provide the process selected from the following.
(Iii) a supply step of supplying water so as to prevent glass particles from adhering to the glass substrate surface;
(Iv) a recovery step for recovering the coolant;
(V) a filtering step of filtering the coolant;
(Vi) A circulation step for circulating the coolant.

  In the step (i), the cooling liquid may be supplied to the contact portion between the grindstone and the glass substrate end face, and for example, supplied using a cooling liquid supply apparatus included in an end face grinding apparatus described later.

  Although it does not specifically limit as a nonionic surfactant, For example, alcohol amines, glycols, and ethers can be used. As alcohol amines, for example, diethanolamine, triethanolamine, and alkanolamine can be used. As glycols, for example, ethylene glycol and propylene glycol can be used.

  As the water used for the cooling liquid, pure water, ultrapure water, or RO water that has been subjected to filter treatment with a reverse osmosis membrane can be used. In addition, the water used for the cooling liquid is pure water that has been subjected to ion exchange treatment, EDI (Electrodeionization) treatment, filter treatment with a reverse osmosis membrane, and decarbonation treatment through a decarbonation device. It is preferable in terms of keeping the surface clean. Specifically, foreign substances such as fine particles are removed from the water using a filter, and after this, organic substances are removed by permeating activated carbon, ion exchange treatment, EDI (Electrodeionization) treatment, filter treatment using 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.

In consideration of cooling performance, the concentration of the nonionic surfactant is preferably such that the surface tension of the cooling liquid is 55 mN / m or less, and more preferably 50 mN / m or less.
In consideration of the remaining amount of the nonionic surfactant on the glass substrate surface after glass substrate cleaning, the concentration at which the surface tension of the cooling liquid is 35 mN / m or more is preferable, and 40 mN / m or more is more preferable. When the concentration of the nonionic surfactant is within the above range, the remaining of the nonionic surfactant on the glass substrate surface is reduced.
If the organic matter remains on the glass substrate surface, there arises a problem that the black matrix is peeled off from the glass substrate. Organic substances include organic substances derived from slip paper contained in laminates of glass substrates, organic substances in atmospheres under transport and storage environments, as well as nonionic surfactants in the cooling liquid remaining on the glass substrate surface. It is. Therefore, by defining the upper limit of the concentration of the nonionic surfactant, it is possible to reduce the nonionic surfactant remaining on the surface of the glass substrate and suppress the peeling of the black matrix.

To adjust the concentration of the nonionic surfactant, create a calibration curve for the relationship between the surface tension and the coolant containing the nonionic surfactant having various concentrations in advance. Thus, water and a nonionic surfactant may be added so as to obtain a desired surface tension.
The surface tension is measured by, for example, a commercially available surface tension meter using a static surface tension measurement method, a ring method, or a plate method.

The coolant is preferably adjusted to have a pH of 8 to 11, and more preferably pH 8 to 10. The pH of the cooling liquid is adjusted by, for example, adding an alkali neutralizing agent to the chemical liquid or adjusting the concentration when using an inorganic alkali. As an alkali neutralizer, the neutralizer containing caustic soda, quicklime, slaked lime, limestone, magnesium hydroxide etc. can be used, for example.
When the pH of the cooling liquid is within the above range, the glass substrate is not eroded by the cooling liquid, but the organic matter adhering to the surface of the glass substrate is dissolved by the cooling liquid, so that the organic matter can be easily removed during cleaning. The cleaning property of the glass substrate can be improved.

The cooling liquid is supplied to the contact point between the glass substrate end face and the grindstone, and then the aromatic compound remaining on the surface of the glass substrate when the glass substrate is washed with pure water is, for example, 5 ng or less per 1 cm ^2. It is preferable to adjust. Here, the aromatic compound is a group of cyclic unsaturated organic compounds, and is an organic substance or a hydrophobic organic substance that causes a decrease in the adhesion of the black matrix resin to the surface of the glass substrate. The organic matter adhering to the surface of the glass substrate after the pure water cleaning of the glass substrate may be 10 ng or less per 1 cm ^{2 of} the glass substrate surface, and more preferably 5 ng or less.
Moreover, it is preferable that the organic substance adhering to the surface of the glass substrate after washing | cleaning of the alkaline cleaning liquid of a glass substrate is 0.15 ng or less per 1 cm < ² > of glass substrate surfaces.
When a coolant containing liquids other than water is used for the end face processing of glass substrates for displays, the quality of the surface of the glass substrate changes, and even if the surface of the glass substrate is cleaned by the cleaning process, the yield of the panel manufacturing process is reduced. May bring. As one factor of the yield reduction, the adhesion of the black matrix to the surface of the glass substrate is changed, and for example, there has been a problem that the black matrix is peeled off from the surface of the glass substrate. By using the cooling liquid, high adhesion can be maintained even when a semiconductor element or a color filter is formed on the surface of the glass substrate.

In the control step of the above step (ii), the concentration of the nonionic surfactant in the cooling liquid is measured, the reference concentration and the measured value are compared, and the reference concentration and the measured value are different. In addition, the concentration of the nonionic surfactant in the coolant is controlled so as to be a reference concentration.
The concentration of the nonionic surfactant may be measured directly or indirectly. Although the method for indirectly measuring is not particularly limited, for example, the concentration is measured using a refractive index. In this case, the refractive index is measured in advance for an aqueous solution containing a nonionic surfactant with a known concentration, and a calibration curve is created for the relationship between the nonionic surfactant concentration and the refractive index. And the refractive index of a cooling fluid is measured and the density | concentration of the nonionic surfactant in a cooling fluid is determined from the measured value of a refractive index using a calibration curve.
A commercially available refractometer can be used for the measurement of the refractive index, and the refractive index may be measured according to JISK 0062.
The reference concentration can be determined depending on the purpose, but considering the cooling performance, the surface tension is preferably selected from a concentration that is 55 mN / m or less, more preferably 50 mN / m or less. In consideration of the cooling performance of the grindstone and the suppression of the remaining nonionic surfactant, the surface tension of the coolant is preferably 55 mN / m or less, more preferably 50 mN / m or more, and preferably 35 mN / m. As described above, the concentration is preferably selected so as to be 40 mN / m or more.
If the concentration, that is, the surface tension fluctuates, the cooling ability will not be constant and the life of the wheel will be shortened.
When the reference concentration and measured value are different from each other, the measured value can be lower than the reference concentration as a method for managing the concentration of the non-ionic surfactant in the coolant so that the reference concentration is obtained. For example, a nonionic surfactant is added to adjust the concentration to be constant. Conversely, if the measured value is higher than the reference concentration, water is added to adjust the concentration to a constant value. As described above, when the concentration of the nonionic surfactant is indirectly measured using, for example, the refractive index, the reference concentration is also converted into the refractive index, and the refractive indexes are compared with each other. Also good.

  In the step (iii), water is supplied to the surface of the glass substrate, the surface of the glass substrate is covered with a film of water, and adhesion of glass particles is prevented. In order to effectively prevent the adhesion of glass particles to the glass substrate surface, it is preferable to perform this step simultaneously with or immediately after the grinding of the glass substrate end surface, in order to reduce the amount of water mixed in the recovered coolant. For this, it is preferable to perform this step immediately after grinding.

In the above step (iv), the coolant is recovered using, for example, a coolant recovery device included in an end surface grinding device described later. The recovery of the cooling liquid can be performed between the above steps (i) and (ii).
In the step (v), the cooling liquid is filtered. Glass waste etc. are contained in the cooling liquid which passed through said process (i). When these are sandwiched between the grinding wheel and the glass, processing defects are caused, and therefore it is preferable to remove them with a filter. The filter used for the filtration is preferably a filter that can remove glass dust of 5 μm or more, more preferably 1 μm or more, and further preferably 0.3 μm or more. If a filter capable of removing finer glass debris than the above is used, the filter replacement cycle is accelerated and the operating rate is lowered.

Furthermore, about the glass particle which cannot be removed with a filter, you may remove by the process of controlling the quantity of the glass particle in a cooling liquid below to constant. Even if the glass particles are so small that they do not affect the end face processing, adhesion to the glass surface may be a problem in the glass substrate for LCD. If a convex of several μm is formed on the surface of a glass substrate, there is a possibility that a wiring defect in manufacturing a TFT panel, a gap variation of a liquid crystal when used as a liquid crystal panel, and display unevenness due to this may occur. Removal of particles by a filter is difficult or expensive. However, if the amount of fine particles in the coolant is small, the possibility of adhering to the surface of the glass substrate is low. Thus, by controlling the content of fine particles, it is possible to prevent particles from adhering to the glass substrate surface.
As the management of the fine particle content, for example, the amount of glass particles in the coolant is measured, the measured value is compared with the reference value, and the coolant is replaced when the measured value is equal to or higher than the reference value.
The amount of glass particles can be measured indirectly using, for example, electrical conductivity. When measuring using electrical conductivity, it can utilize that electrical conductivity rises, when the glass particle in aqueous solution increases. Specifically, a calibration curve is prepared in advance for the relationship between the known glass particle amount and the electrical conductivity, the electrical conductivity in the coolant is measured, and the measured value of the electrical conductivity is measured using the calibration curve. The amount of glass particles can be calculated.
The reference value is set as a reference value, for example, by preparing a cooling liquid containing a glass particle amount sufficient to maintain the surface cleanliness of the glass substrate, measuring the glass amount in advance. The reference value is appropriately determined in consideration of the required surface cleanliness of the glass substrate.
As for the comparison between the measured value and the reference value, when the glass particle amount is measured by electric conductivity, the electric conductivities may be compared with each other.

  Further, in the step (vi), the coolant is circulated. The temperature of the coolant at the time of circulation may be 20 ° C. or less, and the coolant may be supplied to the contact portion between the grindstone and the glass substrate end surface.

(3) End surface grinding apparatus An example of an end surface grinding apparatus that can be used in the present embodiment will be described below with reference to FIG.
The end surface grinding device 200 mainly includes a housing 202, a chamfering grindstone 203, a motor (not shown), a coolant supply device 204, a coolant recovery device 205, a filtration device 206, and a concentration control device 207. Prepare.
The housing 202 is a rectangular parallelepiped container assembled from metal plates.
The chamfering grindstone 203 is provided in the internal space of the housing 202 and chamfers the end surface of the glass substrate 201 inserted from a slit provided on the outer surface of the housing 202.
The motor is attached to the upper surface of the housing 202, and is connected to the chamfering grindstone 203 through a shaft. The motor is a power source for rotating the shaft to rotate the chamfering grindstone 203 around the rotation axis.
The cooling liquid supply device 204 supplies the cooling liquid stored in the external space of the housing to the side surface of the chamfering grindstone 203 in the internal space of the housing via a pipe penetrating the housing.
The cooling liquid recovery device 205 is connected to the housing via a suction pipe, sucks the gas in the internal space of the housing 202, makes the internal space of the housing negative pressure with respect to the external space of the housing, and sucks liquid and gas can do.
The filtration device 206 removes the glass piece by filtering the coolant recovered by the coolant recovery device 205 through a filter.
The concentration control device 207 includes a measurement unit that measures the concentration of the nonionic surfactant in the coolant, a comparison unit that compares the reference value and the measurement value, and a command for concentration adjustment when the reference value and the measurement value are different. And a concentration adjusting unit that adjusts the concentration of the coolant to a target concentration in response to an instruction from the commanding unit. The coolant that has passed through the concentration adjusting unit is supplied to the coolant supply device 204.

  Hereinafter, the present invention will be described in more detail with reference to examples. In addition, this invention is not limited to a following example.

Example 1
While supplying the coolant, which is an aqueous solution containing a nonionic surfactant, to the contact portion between the grindstone and the end surface of the glass substrate, the contact portion was cooled to process the end surface of the glass substrate.

  A diamond wheel with abrasive grains # 600 was used as the grindstone. The diamond wheel was rotated at a peripheral speed of 33 m / sec, and the glass substrate was conveyed at a feed speed of 7 m / min.

As the glass substrate, a glass substrate having a size of 1100 mm × 1300 mm × 0.7 mm having the following composition was used.
SiO ₂ : 60% by mass,
B ₂ O ₃ : 10% by mass,
Al ₂ O ₃ : 19.8% by mass,
CaO: 5% by mass,
SrO: 5% by mass,
SnO _2: 0.2 wt%.

  The concentration of the aqueous solution containing the nonionic surfactant was adjusted so that the surface tension was 53 mN / m. Here, the concentration of the nonionic surfactant in the cooling liquid is adjusted with a commercially available surface tension meter using a static surface tension measurement method for the cooling liquid containing a nonionic surfactant with a known concentration. Was measured, a calibration curve was created in advance for the relationship between the concentration of the nonionic surfactant and the surface tension, and the coolant was adjusted using the created calibration curve.

  The processing of the end face of the glass substrate was continuously performed until a plurality of glass substrates were continuously processed and the processing distance exceeded 1000 m. At this time, in order to prevent the scattered glass particles from adhering to the substrate surface, a shower was applied to the glass substrate surface from above. The supply and recovery of the cooling liquid was performed by an end surface grinding apparatus shown in FIG. Furthermore, the recovered coolant was filtered using a filter.

Next, the concentration of the nonionic surfactant in the recovered coolant was indirectly measured using the refractive index.
Here, the refractive index is measured by measuring the refractive index according to JISK 0062 for a coolant containing a nonionic surfactant whose concentration is known at 20 ° C., and measuring the refractive index and the nonionic surfactant concentration. A calibration curve was created in advance for the relationship between and the concentration of the nonionic surfactant was determined from the measured value of the refractive index of the coolant using the created calibration curve.

The concentration of the obtained nonionic surfactant was lower than the target value (concentration at which the surface tension was 53 mN / m) because the amount of shower water mixed was larger than the evaporation amount due to grinding heat.
Therefore, using the calibration curve showing the relationship between the nonionic surfactant concentration and the surface tension created above, the addition amount of the nonionic surfactant necessary to obtain the target value is calculated, and the pump A The calculated amount of nonionic surfactant was added to the cooling liquid, and the concentration of the cooling liquid was adjusted to the target value.

Next, the obtained cooling liquid was circulated, and the end face was processed under the same conditions as above to produce a glass substrate for a color filter.
As a result, even if the number of workpieces increased (even if the machining distance was long), the machining current value required for driving the diamond wheel was small and stable. Moreover, the processing defect did not arise in the glass substrate end surface.

Next, in order to confirm the surface quality of the processed glass substrate, a black matrix resin pattern is formed on the glass substrate, and compared with the glass substrate when water is used as the cooling liquid, the black matrix adheres more closely. Sex was judged. Specifically, a black matrix resin is applied to the surface of each glass substrate to form a pattern with a film thickness of 1 μm and a line width of 1 μm to 15 μm, and the black matrix resin is peeled off from the glass surface and the residue. Was confirmed.
As a result, it was confirmed that there was no change in the adhesion of the black matrix between the glass substrate of Example 1 and the glass substrate when water was used as the coolant.

Next, the processed glass substrate is put into the above-described cleaning step S6, the surface of the glass substrate is cleaned, and then a black matrix resin pattern is formed on the glass substrate, and water is used as a coolant. Compared with the glass substrate in the case, the adhesion of the black matrix was determined. Specifically, a black matrix resin is applied to the surface of each glass substrate to form a pattern with a film thickness of 1 μm and a line width of 1 μm to 15 μm, and the black matrix resin is peeled off from the glass surface and the residue. Was confirmed.
As a result, even after cleaning, it was confirmed that there was no change in the adhesion of the black matrix between the glass substrate of Example 1 and the glass substrate when water was used as the coolant.

(Example 2)
In Example 1, the concentration of the nonionic surfactant was changed from a concentration at which the surface tension was 53 mN / m to a concentration at which the surface tension was 50 mN / m, and the surface tension was 53 mN as a target value. A glass for color filters was prepared by circulating the cooling liquid under the same conditions as in Example 1 except that the concentration was changed to a concentration so that the surface tension was 50 mN / m. A substrate was produced.
As a result, as compared with Example 1, even if the number of processed sheets increased (even if the processing distance was long), the increase in the processing current value was small and stable. Moreover, the processing defect did not arise in the glass substrate end surface.

Next, the adhesion of the black matrix was determined under the same conditions as in Example 1 except that the glass substrate in Example 1 was changed to the glass substrate in Example 2.
It was confirmed that there was no change in the adhesion of the black matrix between the glass substrate of Example 2 and the glass substrate when water was used as the coolant before and after the cleaning step S6.

(Example 3)
In Example 1, the concentration of the nonionic surfactant was changed from the concentration at which the surface tension was 53 mN / m to the concentration at which the surface tension was 38 N / m, and the surface tension was 53 mN as the target value. Except that the concentration is changed to a concentration so that the surface tension is 38 mN / m, the end surface is processed by circulating the coolant under the same conditions as in Example 1, and the flat panel display is used. A glass substrate was produced.
As a result, as compared with Example 2, the increase in the machining current value was small and stable even when the number of machining sheets increased (the machining distance increased). Moreover, the processing defect did not arise in the glass substrate end surface.

Example 4
In Example 1, the concentration of the nonionic surfactant in the recovered coolant was tested under the same conditions as in Example 1 except that the glass substrate surface was not showered during end face processing. Was measured using the refractive index.
The measured value obtained was higher than the target value (concentration at which the surface tension was 55 mN / m) because water was evaporated due to grinding heat but no shower water was mixed. Therefore, using the calibration curve showing the relationship between the concentration of the nonionic surfactant and the surface tension created above, the amount of water necessary to obtain the target value was calculated.
Next, the pump B was pushed, and the calculated amount of water was added to the coolant, and the concentration of the coolant was adjusted to the target value.
Next, the obtained cooling liquid was circulated and used for end face processing under the same conditions as described above to produce a glass substrate for a color filter.
As a result, as in Example 1, even when the number of workpieces increased (even when the machining distance was long), the machining current value did not increase and was stable. Moreover, the processing defect did not arise in the glass substrate end surface.

Next, the adhesion of the black matrix was determined under the same conditions as in Example 1 except that the glass substrate of Example 1 was changed to the glass substrate of Example 5.
It was confirmed that there was no change in the adhesion of the black matrix between the glass substrate of Example 5 and the glass substrate when water was used as the coolant before and after the cleaning step S6.

(Comparative Example 1)
A glass substrate for a color filter was produced under the same conditions as in Example 1 except that the concentration of the recovered coolant was not adjusted.
As a result, as in Example 1, when the end surface processing was performed by circulating the coolant, processing defects were continuously or sporadically formed on the end surface of the processed glass substrate until the processing distance reached 1000 m. Occurred.
It was also confirmed that the machining current value indicating the machining load also increased from the start of machining.
In the grinding of the end face, the penetration of the cooling liquid is insufficient until the processing point between the processing wheel and the glass substrate. As a result, when continuous processing is performed, processing defects are generated, and further, the processing load current value is increased. In this case, a dressing operation for the machining groove of the machining wheel is required.

Next, the adhesion of the black matrix was determined under the same conditions as in Example 1 except that the glass substrate of Example 1 was changed to the glass substrate of Comparative Example 1.
It was confirmed that there was no change in the adhesion of the black matrix between the glass substrate of Comparative Example 1 and the glass substrate when water was used as the coolant before and after the cleaning step S6.

From the above results, according to the glass substrate manufacturing method of Examples 1 to 4 according to the present invention, it is possible to stably cool the grindstone, reduce wear due to the heat of the grindstone, and extend the life of the grindstone. . Furthermore, by defining the upper limit concentration of the nonionic surfactant in the cooling liquid, the residual of the nonionic surfactant on the glass substrate surface is reduced, and the black matrix adhesion is extremely excellent. Is possible.
On the other hand, according to the manufacturing method of the glass substrate of Comparative Example 1 in which the coolant concentration control was not performed, the dressing operation of the processing groove is required, which leads to shortening of the life of the grindstone.

  As mentioned above, although the manufacturing method of the glass substrate of this invention was demonstrated in detail, this invention is not limited to the said embodiment, In the range which does not deviate from the main point of this invention, you may make various improvement and a change. Of course.

10, 201 Glass substrate 11a, 11b 1st end surface 12a, 12b 2nd end surface 100 End surface processing apparatus 101 1st chamfering apparatus 102 Rotating device 103 2nd chamfering apparatus 104 Corner cut apparatus 111, 112, 113 Diamond wheel 121, 122 , Polishing wheel 202 Housing 203 Grinding stone 204 Coolant supply device 205 Coolant recovery device 206 Filtration device 207 Concentration control device

Claims (6)

A glass substrate manufacturing method comprising an end face processing step of processing an end face of the glass substrate with the grindstone while supplying a coolant to a contact portion between the grindstone and the glass end face,
In the end face processing step,
A cooling step of cooling the contact portion by supplying a coolant that is an aqueous solution containing a nonionic surfactant to the contact portion;
Wherein in the cooling liquid and the measurement result of the concentration of non-ionic surface active agent, compared with the concentration as a reference, if said measurement result and concentration serving as the reference is different, the non-ionic surfactant a control step of the concentration to manage the concentration of the nonionic surfactant to a concentration serving as the reference,
The concentration of the nonionic surfactant is a measured value of the refractive index of the cooling liquid with reference to the correspondence relationship between the concentration of the nonionic surfactant and the refractive index of the cooling liquid prepared in advance. The manufacturing method of the glass substrate calculated | required from . Furthermore, it comprises a circulation step of circulating the coolant that has undergone the control step,
Measuring the electrical conductivity of the circulating coolant, and when the measurement result of the electrical conductivity is equal to or higher than a preset value, the step of replacing the coolant with another coolant , The manufacturing method of the glass substrate of Claim 1. The manufacturing method of the glass substrate of Claim 1 or 2 whose pH of the said cooling fluid is 8-11. Furthermore, the manufacturing method of the glass substrate of any one of Claims 1-3 provided with the supply process which supplies water to the said glass substrate surface during supplying the said cooling fluid to the said contact part . The glass substrate is a glass substrate for a color filter, method of manufacturing a glass substrate for a color filter according to any one of claims 1-4. The said glass substrate is a manufacturing method of the glass substrate for flat panel displays of any one of Claims 1-4 which is a glass substrate for flat panel displays.

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