JP2014188420A - Method of manufacturing glass substrate, method of manufacturing glass substrate for display, and method of cleaning end surface of the glass substrate for display - Google Patents

Abstract

Cleaning is performed to remove residual foreign matters from an end surface of a glass substrate, and dust generation in a subsequent process is suppressed.
A method for producing a glass substrate according to the present invention is the method for producing a glass plate having a polished processing portion, wherein the processing portion is polished and brought into contact with a magnetic abrasive grain. By supplying an acidic cleaning solution to the processing unit and charging the processing unit and the surface of the magnetic body attached to the processing unit to the same, the processing unit and the magnetic body are repelled, and the metal deposit Is transferred to an acidic cleaning solution.
[Selection] Figure 1

Description

  The present invention relates to an end face treatment of a glass plate and a method for producing a glass substrate for display.

  A manufacturing process of a display panel such as a liquid crystal display or a glass substrate for display includes a step of chamfering an end surface formed by cutting the glass substrate. The end surface of the glass substrate is ground by a diamond wheel to remove cracks and sharp edges caused by cutting. For example, the shape is adjusted so that the cross section has an R shape by a diamond wheel. Thereafter, the end surface of the glass substrate is polished by a polishing process using a flexible polishing wheel made of, for example, a foamed resin.

  As a polishing technique, a technique using a polishing slurry containing a magnetic material for polishing an end face of a glass substrate is known, as described in Patent Document 1. Further, as described in Patent Documents 2 and 3, a technique is known that uses a polishing slurry containing a magnetic material to perform mirror surface processing.

  Moreover, it is necessary to remove the glass powder generated at the time of polishing, the attached abrasive, and abrasive grains from the glass substrate by cleaning the front and back surfaces and the end surface of the glass substrate.

International Publication No. 2012/066757 JP 2011-83827 A JP 2000-233359 A

In recent years, with the progress of higher definition and higher resolution display panels, thinning of the TFT wiring width is required on the drive panel side, and further thinning of the black matrix is required on the color filter panel side. In order to meet the demand for such a glass substrate, higher cleanliness is required on the surface of the glass substrate.
Therefore, the present invention provides a technique for cleaning foreign matter adhering to the end face of a glass plate by polishing and a method for producing a glass substrate for display.

  As one of the generation factors of foreign matters attached to the surface of the glass substrate, it is known that foreign matters attached to the end face of the glass substrate remain attached to the surface. Even on the end face of the glass substrate mirror-polished with magnetic abrasive grains, foreign substances that cannot be removed by the conventional cleaning process remain.

  Accordingly, the present invention provides a method for producing a glass plate having a polished processing portion, wherein the processing portion is polished by contacting magnetic abrasive grains, and a cleaning liquid is supplied to the polished processing portion, The surface of the processing unit and the surface of the magnetic material attached to the processing unit are charged to the same polarity to repel the processing unit and the magnetic material, and the magnetic material is transferred to a cleaning liquid and removed. For example, in a glass plate having an end face polished by magnetic abrasive grains, an acidic cleaning liquid, preferably a cleaning liquid containing an organic acid, is supplied to the polished end face, and the surface of the end face of the glass plate is processed. By charging the surface of the metal deposit that is a magnetic substance attached to the end face with the same, the end face and the metal deposit are repelled, and the metal deposit is transferred to the cleaning liquid.

  In addition, the present invention ionizes the surface of a magnetic foreign material adhering to the end surface of the glass substrate under a predetermined pH environment as a method of removing the magnetic material adhering to the end surface of the glass substrate polished with magnetic abrasive grains. In addition, the surface potential of the end surface of the glass substrate is made positive, and magnetic foreign substances are levitated from the end surface of the glass substrate, and are prevented from being reattached by chelating action, and washed and removed from the glass substrate. A substrate manufacturing process is provided. The glass substrate is subjected to an end surface rinsing step after the end surface cleaning step, and then the glass substrate surface is cleaned with an alkali cleaning detergent or the like.

Moreover, the manufacturing method of the glass substrate of the present invention includes a forming step of forming a glass sheet from molten glass, a cutting step of cutting the glass sheet to form a glass substrate, and an end face of the glass substrate with a magnetic body. An end surface treatment step for mirror polishing by bringing the held magnetic abrasive grains into contact, and an iron-based fine particle caused by the magnetic abrasive particles adhering to the glass end surface in the mirror polishing step for an acidic chemical solution having a pH of 2 or less A cleaning step of cleaning using Fe, and the cleaning step reduces Fe ³⁺ constituting the iron-based fine particles to Fe ²⁺ ions, and forms a complex by the bidentate coordination or more of the Fe ions. Features.

Moreover, the manufacturing method of the glass substrate for a display of the present invention includes a forming step of forming a glass sheet from molten glass, a cutting step of cutting the glass sheet to form a glass substrate, and a magnetic force on the end surface of the glass substrate. It has an end surface processing step of performing mirror polishing by bringing magnetic abrasive grains held on the body into contact with each other, and a cleaning step of cleaning with the end surface acidic chemical solution. The end face processing step is magnetic abrasive grain polishing using magnetic abrasive grains, and is arranged with an interval in the axial direction of the rotary shaft, and rotates with the rotary shaft. A magnetic field forming unit comprising: a magnetic fluid for polishing, which is constituted by the magnetic abrasive grains and the liquid and is held by the magnetic field formed between the first magnetic body and the second magnetic body. Using the polishing wheel provided, the concentration of the magnetic abrasive grains in the magnetic fluid is adjusted to 85% or more, and the magnetic fluid is in contact with the end surface of the glass substrate in a state where the rotating shaft is rotated. And mirror polishing. The cleaning step comprises the iron-based fine particles using an acidic chemical solution having a pH of 2 or less in order to remove the iron-based fine particles caused by the magnetic abrasive grains adhering to the glass end surface in the end surface treatment step. the ^{Fe 3+} which is reduced to ^{Fe 2+} ions, two or more places of the ^{Fe 2+} ions and forming a complex coordinated.

  Further, the method for cleaning an end surface of a glass substrate for display of the present invention is a method for cleaning an end surface of a glass substrate that has been end-polished using a magnetic abrasive grain, and the end surface has a predetermined pH or lower, preferably 2 or lower. Preferably, an acidic chemical solution of 1.6 or less is supplied to physically wash the end face. The acidic chemical used in the washing step has a chelating effect at a predetermined pH, and includes salicylic acid, phthalic acid, glyoxylic acid, oxalic acid, fumaric acid, maleic acid, malonic acid, succinic acid, gluconic acid, trans-aconite. Organic acids such as acid, tartalonic acid, lactic acid, pyruvic acid, citric acid, isocitric acid, glycolic acid, malic acid, tartaric acid. Aminocarboxylic acids such as nitrilotriacetic acid, ethylenediaminetetraacetic acid, hydroxyethylethylenediaminetriacetic acid, and diethylenetriaminepentaacetic acid; One or more kinds selected from amino acids such as serine, aspartic acid, glutamic acid, cysteine and the like are used, and magnetic abrasive grains adhering to the end face of the glass substrate are removed.

  According to the method for cleaning a glass plate of the present invention, magnetic substances and metal deposits adhering to the glass surface can be removed, and reattachment to the glass surface can be suppressed.

It is process drawing explaining the process of the manufacturing method of the glass substrate of this invention. It is a figure for demonstrating from the melt | dissolution process of this invention to a cutting process. It is a figure for demonstrating the end surface processing of this invention. It is a figure for demonstrating the grinding | polishing process using the magnetic body abrasive grain of this invention. It is a figure for demonstrating the glass substrate processed by this invention. It is a figure for demonstrating the washing | cleaning apparatus of this invention. It is a figure for demonstrating the washing jig with which the washing | cleaning apparatus of this invention is equipped. It is a figure for demonstrating the process of the glass surface in other embodiment of this invention.

Hereinafter, the manufacturing method of the portable glass substrate of the present embodiment will be described with reference to the drawings.
(1) Overview of Glass Substrate Manufacturing Method FIG. 1 is a partial flowchart of the glass substrate manufacturing method according to this embodiment.
As shown in FIG. 1, the glass substrate is manufactured through steps of a melting step T1, a forming step T2, a cutting step T3, a processing step T4, a cleaning step T5, and an inspection step T6.

A part (apparatus 100) of the manufacturing process of the glass substrate of this invention is demonstrated using FIG.
In the melting step T1, the glass raw material is heated and melted in the melting apparatus 200 to obtain molten glass. And the gas component contained in a molten glass is discharge | released from a molten glass within the refining apparatus 300, or the gas component contained in a molten glass is absorbed in a molten glass. For example, the glass raw material has a composition such as SiO ₂ or Al ₂ O ₃ .

  In the forming step T2, the clarified molten glass is supplied to the forming apparatus 500 through the transfer pipe 400 and formed into a strip-shaped glass sheet G1.

  In the cutting step T3, the glass sheet G1 is cut in the width direction by a cutting device (not shown) to be turned into a single sheet. Further, the four sides are cut so as to have a predetermined size, and a glass substrate G having a product size is obtained.

  In the processing step T4, the end surface formed by cutting is processed by the first end surface processing machine 30 shown in FIG. The end surface 33 of the glass substrate G is processed by contacting the first grinding wheel 31 and the second grinding wheel 32 that are rotated by a rotating shaft (not shown) on both end surfaces of the moving glass substrate G. After the end surface 33 on the long side of the glass substrate G is processed, the end surface 33 on the short side is processed. Thereafter, mirror polishing of the end face 33 is performed by the polishing apparatus 40 provided in the second end face processing machine 34 shown in FIG. Here, a polishing slurry containing a magnetic material is used and mirror-polished. The polishing slurry containing a magnetic substance includes magnetic abrasive grains in which the magnetic substance mainly acts as polishing abrasive grains, and magnetic fluid that acts as a carrier for the magnetic substance to mainly carry abrasive grains.

  Next, a description will be given of a cleaning process including a process of removing from the end surface a magnetic material that is a metal deposit adhered in the polishing process of the processing process T4.

  In the cleaning step T5, the end surface cleaning jig 61 cleans the end surface of the glass substrate G that has been mirror-polished in the processing step T4 by the first end surface cleaning device 60 shown in FIG. In the first end surface cleaning device 60, first end surface cleaning jigs 61 are provided on both sides of the glass substrate G transported on the transport roller 62, and a shower is sprayed from the main surface side to the end surface side of the glass substrate G. An end face cleaning nozzle 63 is provided.

  The glass substrate G that has passed through the first end surface cleaning device 60 is then washed away by the second end surface cleaning device 70 shown in FIG. In the second end surface cleaning device 70, second end surface cleaning jigs 64 are provided on both sides of the glass substrate G transported on the transport roller 62.

  The glass substrate G whose long side end surface 33 has been cleaned by the first end surface cleaning device 60 and the second end surface cleaning device 70 is rotated by 90 degrees with the reversing machine (not shown), The short side of the substrate G is cleaned in the same manner as the long side.

  Further, after cleaning the four sides of the end surface 33 of the glass substrate G, the main surface of the glass substrate G is cleaned. The front and back surfaces of the glass substrate G are cleaned by the front surface cleaning apparatus 80 shown in FIG. A cleaning roller 65 is provided on the front side / back side of the glass substrate G transported on the transport roller 62, and an alkaline cleaning detergent for the glass substrate is applied to clean the main surface of the glass substrate G. In this embodiment, the cleaning roller 65 is used in combination with a brush roller and a sponge roller, and organic substances and particles adhering to the surface of the glass substrate are removed.

  In the inspection step T6, the end face and the main surface of the glass substrate are inspected, and then shipped to a display panel manufacturer or the like as a display glass substrate.

Hereinafter, end face processing and end face cleaning of the present invention will be described with reference to the drawings.
The processing steps of the present embodiment include the first and second grinding steps shown in FIG. 3 and the polishing step shown in FIG.

First, the 1st end surface processing machine 30 and the 2nd end surface processing machine 34 are demonstrated.
As shown in FIG. 3, in the first end face processing machine 30, the first grinding wheel 31 and the second grinding wheel 32 provided at both ends of the glass substrate are first long while conveying the glass substrate G in the direction of the arrow. The end face on the side is ground sequentially. Then, after the long side is ground, the short side is similarly ground, and orientation flat processing and corner cutting (not shown) are performed as necessary.

The first grinding wheel 31 is a grinding wheel in which diamond abrasive grains are hardened with a metallic binder containing iron. As the binder for the first grinding wheel, a binder having higher hardness and rigidity than the binder for the second grinding wheel 32 is used. Here, hardness is Shore hardness, and rigidity is Young's modulus. If the binder of the first grinding wheel 31 is a metal, another metal binder such as a cobalt or bronze may be used. Further, if the hardness and rigidity are higher than the binder of the second grinding wheel, a ceramic binder may be used as the binder of the first grinding wheel 31. For the first grinding wheel 31, for example, diamond abrasive grains having a grain size of about # 300 to # 400 defined by JIS R6001-1987 can be used. In the present embodiment, the first grinding wheel 31 uses diamond abrasive grains having a particle size of # 400. The abrasive grains are not limited to diamond but may be CBN (borazone).
The grain size of the first grinding wheel 31 may be equal to or coarser than the grain size of the diamond abrasive grains of the second grinding wheel 32.

The second grinding wheel 32 is a grinding wheel obtained by hardening diamond abrasive grains with a resin-based binder containing epoxy. As the binder for the second grinding wheel 32, one having lower hardness and rigidity than the binder for the first grinding wheel 31 is used. As the binder of the second grinding wheel 32, a ceramic binder may be used as long as the hardness and the synthesis are lower than the binder of the first grinding wheel 31. As long as it is resin-based, for example, a polyimide-based material may be used. The abrasive grains are not limited to diamond but may be CBN. In the present embodiment, the second grinding wheel 32 uses diamond abrasive grains having a grain size of # 400 defined by JIS R6001-1987.
Note that the grain size of the abrasive grains of the first grinding wheel 31 is preferably equal to or coarser than the grain size of the abrasive grains of the second grinding wheel 32 for efficient grinding.

  In the first grinding step, the end surface of the glass substrate G is ground by a predetermined grinding amount with a shape formed on the first grinding wheel 31, for example, a grinding groove having a predetermined curvature. As a result, the end surface of the glass substrate G is retreated to the center side of the glass substrate from the original end surface, and the cross-sectional shape of the end surface is a convex having a curvature corresponding to the cross-sectional shape of the grinding groove of the first grinding wheel 31. It is ground into a shape, arc shape or R shape. Here, the grinding amount is the distance from the original end face before grinding to the apex of the convex end face after grinding which has been ground and retreated. That is, the amount of the end surface of the glass substrate G ground in the direction of the main surface of the glass substrate G. The amount of grinding of the glass substrate G by the first grinding wheel 31 is, for example, in the range from 40 μm to 80 μm. It is preferable that the conveyance speed of the glass substrate G in a 1st grinding process is 10 m / min or more from a viewpoint of ensuring productivity. In this embodiment, the conveyance speed of the glass substrate G is 10 m / min.

  In the first grinding step, the glass substrate G is adjusted such that the maximum height Rmax defined by JIS B 0601-1982 of the end surface of the glass substrate G is at least 10 μm and 18 μm, more preferably 13 μm and 14 μm. The end face of is ground. Moreover, the arithmetic average roughness Ra prescribed | regulated by JISB0601-1994 of the end surface of the glass substrate G will be about 0.5 micrometer, for example.

  Thereafter, in a second grinding step provided continuously with the first grinding step, the glass substrate G is ground at the end face by the grinding groove of the second grinding wheel 32. Thereby, the cross-sectional shape of the end surface of the glass substrate G is ground into a convex shape, a circular arc shape, or an R shape with a curvature corresponding to the cross-sectional shape of the grinding groove of the second grinding wheel 32. In the present embodiment, the grinding groove of the second grinding wheel 32 is made substantially the same shape as the grinding groove of the first grinding wheel 31, so that the apparent shape of the end surface of the glass substrate is not changed. The end face is ground for a predetermined grinding amount.

  The amount of grinding of the glass substrate G by the second grinding wheel 32 is in the range of 10 μm to 30 μm, for example. In the second grinding step, the end surface of the glass substrate G is such that the maximum height Rmax defined by JIS B 0601-1982 of the end surface 33 of the glass substrate G is at least 4 μm and 8 μm or less, more preferably about 6 μm. Grind. The arithmetic average roughness Ra of the end face of the glass substrate G is 0.2 μm or less, for example, about 0.1 μm to 0.2 μm.

  After processing the long side of the glass substrate G by the first and second grinding steps described above, the direction of the glass substrate G is rotated 90 degrees by a reversing machine (not shown), and the short side of the glass substrate G is changed to the long side. Process the same as the side.

  In addition, about the rotation direction of the 1st grinding wheel 31 and the 2nd grinding wheel 32, the moving direction of the outer peripheral surface of the grinding wheel 31 in the point which contacts the glass substrate G becomes the same as the conveyance direction of the glass substrate G. It may be set or may be set in the opposite direction. In the present embodiment, the movement direction of the outer peripheral surfaces of the first grinding wheel 31 and the second grinding wheel 32 at the point of contact with the glass substrate G in the first and second grinding steps is the direction opposite to the conveyance direction of the glass substrate G. Thus, the first and second grinding wheels 31 and 32 are rotated in one direction.

  In the grinding step, as described above, the cross-sectional shape of the end surface of the glass substrate G is ground into a convex shape having a curvature, an arc shape, or an R shape, and the arithmetic average roughness Ra of the end surface of the glass substrate G is 0. . Grind to 2 μm or less. However, a layer containing micro cracks called micro cracks or hair cracks is formed on the end surface of the glass substrate G ground by the grinding wheel 12a which is a diamond wheel. This layer is called a work-affected layer or a brittle fracture layer, and is present in a thickness of about 1 μm to 3 μm even after the first grinding step and the second grinding step. Due to the presence of such a layer, the breaking strength at the end face of the glass substrate G is reduced, or the glass falls off from minute cracks. In order to remove such a layer and improve the breaking strength at the end face of the glass substrate G, a polishing process is performed.

  In the polishing process, the work-affected layer or the fragile fracture layer on the end surface of the glass substrate G is removed, and the glass substrate G is polished by the polishing wheel 12b so that the arithmetic average roughness Ra of the end surface of the glass substrate G is less than 0.01 μm, for example. Polish the end face of G.

  As shown in FIG. 4, the glass substrate G that has finished the grinding of the end surfaces 33 of the glass substrate on the long side and the short side in the grinding step is transported to a position where polishing is performed by the polishing wheel 12 b. Thereafter, the glass substrate is processed on a stage (not shown) and processed by the polishing apparatus 40 attached to the second end surface processing machine 34 shown in FIGS. FIG. 4B is a cross-sectional view taken along the line II-II in FIG. The polishing apparatus 40 rotates the polishing wheel 36 around the rotation shaft 35. In the rotating wheel 36, magnetic abrasive grains 37 (also referred to as polishing media) are provided in a gap (also referred to as a magnetic field forming portion) between disk-shaped magnetic bodies 36 a and 36 b provided in parallel with the length direction of the rotating shaft 35. Configured.

  The end of the glass substrate G bites into the magnetic abrasive grains 37 applied with a magnetic field by the magnetic bodies 36 a and 36 b, and the polishing wheel 36 rotates in a state where the end face of the glass substrate G is in contact with the magnetic abrasive grains 37. . Accordingly, the magnetic abrasive grains 37 and the end face of the glass substrate G move relatively, and the end face of the glass substrate G is polished by the magnetic abrasive grains constrained by the magnetic field formed by the magnetic field forming unit.

The abrasive grain shape included in the magnetic abrasive grain 37 is a polygonal shape with a small roundness or an indefinite shape having corners. An indefinite shape having a corner includes a three-dimensional non-uniform shape having one or more sharp corners. Also, having a corner means that the particle is thinning toward the edge, that the cross-sectional outline of the particle forms one or more acute or obtuse angles, and that the edge of the particle is sharp. including.
The magnetic abrasive grains may be spherical. The spherical shape includes not only a circular cross-sectional shape but also a rounded shape with no corners such as an elliptical shape or an oval cross-sectional shape.

  Through the polishing process, the end surface 33 of the glass substrate G has a top portion A and boundary portions B and C between the end surface and the main surface, as shown in FIG. The layer or the fragile fracture layer is removed, and the arithmetic average roughness Ra is mirror-polished to less than 0.01 μm. In particular, when Ra of the boundary portions B and C is less than 0.01, generation of glass powder from the end surface 33 is suppressed, and adhesion to the main surface of the glass substrate G is reduced. Further, the bending strength of the glass substrate G can be improved.

  In addition, although this embodiment demonstrated using the example which grind | polishes the glass substrate G fixed on the stage, you may move the glass substrate G with respect to the fixed grinding | polishing wheel. Further, the end surface 33 of the glass substrate G may be polished one by one, or a plurality of polishing wheels may be prepared and the plurality of sides of the end surface 33 of the glass substrate G may be polished simultaneously. Further, as the polishing slurry containing the magnetic material used in the present embodiment, the magnetic material has been described using the magnetic material abrasive grains in which the magnetic material mainly acts as the abrasive grains. However, the magnetic material is mainly used as a carrier for carrying the abrasive grains. Polishing with a working magnetic fluid may be used.

  Moreover, the measurement of arithmetic removal average roughness Ra which is the removal amount and surface roughness of glass is using the surf comb A1400 by Tokyo Seimitsu Co., Ltd., the vertex A of the end surface of the glass substrate G shown in FIG. This was performed at points B and C in the vicinity of the boundary. The measurement of the glass removal amount was performed with the measurement mode being the cross-section measurement mode, the measurement speed being 0.6 mm / s, the inclination correction being the first half correction, and the measurement distance being 20 mm. Further, the surface roughness was measured by measuring the roughness in the measurement mode, measuring the measurement speed by 0.3 mm / s, and measuring the method by JIS 1994. The arithmetic average roughness Ra is measured with a cutoff of 0.08 and a measurement length of 0.4 mm when Ra <0.02, and a cutoff of 0.25 when 0.02 <Ra <0.2. The measurement length was 1.25 mm, and when 0.1 <Ra <2, the cut-off was 0.8 and the measurement length was 4 mm.

  Next, the cleaning action of the present invention will be described. In the present invention, as a method of removing the magnetic substance attached to the end face of the glass substrate polished with the magnetic abrasive grains, the surface of the magnetic foreign substance attached to the end face of the glass substrate is positively ionized under a predetermined pH environment. At the same time, the surface potential of the end face of the glass substrate was set to be positive so that the magnetic foreign matter floated from the end face of the glass substrate and the reattachment was prevented by chelating action.

  First, in the present invention, in the first end face cleaning step, an acidic chemical solution having a pH of less than 2, preferably less than 1.6 is supplied to the end face of the glass substrate G, and the magnetic abrasive remaining on the end face surface of the glass substrate. Ionization of grains (hereinafter also referred to as magnetic foreign matter) is performed. Thereby, the electrostatic interaction between the glass surface having a positive surface potential and the magnetic foreign material is reduced, and the magnetic foreign material is easily separated from the end surface of the glass substrate. Then, in a state where electrostatic interaction between the glass surface and the magnetic foreign material is reduced, physical cleaning with a sponge is performed to reliably release the magnetic foreign material from the end surface of the glass substrate.

  Furthermore, the chemical solution supplied in the first end face cleaning step includes a chemical solution having a chelating effect on iron in an environment of less than pH 2 to chelate ionized iron and prevent reattachment to the glass. Yes.

The chemical solution having a reducing effect preferably includes at least an acidic chemical solution having a standard oxidation-reduction potential of −0.35 V or less. For example, although there is a need -0.77V for the reduction of Fe ³⁺ ions, it can be lowered reduction potential of Fe ³⁺ ions by the use of a chemical solution with a chelating effect. That is, the reduction effect can be obtained even at the above potential or higher, and the end face cleaning action is further enhanced.

  The magnetic foreign matter is chelated even if the magnetic foreign matter separated from the glass surface by physical cleaning fluctuates to a pH that increases the electrostatic interaction between the glass surface and the magnetic foreign matter surface. This prevents magnetic foreign matter from reattaching to the glass substrate.

  In the second end face cleaning step, rinsing for cleaning and removing the magnetic foreign substance chelated in the first end face cleaning step is performed. In the second end face cleaning step, it is preferable not to bring magnetic foreign substances into the subsequent step. For example, in order to remove the chelated iron component, an acidic chemical solution having a pH of about 2 may be used, and then the chemical solution used for rinsing may be dropped by washing with pure water.

The first end surface cleaning jig 61 in FIG. 6A will be described with reference to FIGS. 7A and 7B.
FIG. 7A shows a part of the end surface of the glass substrate in the first end surface cleaning machine 60.
The first end surface cleaning jig 61 has a cleaning pad 61c provided on a support portion 61b rotated by a rotating shaft 61a, and cleans both ends of the glass substrate conveyed by the conveying roller 62.

  An acidic chemical solution having a pH of about 1.6 is discharged from the end surface cleaning nozzle 63a to the end surfaces of the cleaning pad 61c and the glass substrate. As an example, a mixed solution of oxalic acid and tartaric acid is applied to the end surface of the glass substrate. The cleaning pad 61c contains an acidic chemical solution and slides in contact with the end surface of the glass substrate, thereby bringing chemical cleaning and physical cleaning to the end surface of the glass substrate, and adhering to the end surface of the glass substrate. The magnetic foreign material can be detached from the glass. The detached magnetic foreign matter is chelated by tartaric acid.

  The end surface cleaning jig that contacts the end surface of the glass substrate may be a cleaning roller 611 whose rotational direction is substantially perpendicular to the end surface, as shown in FIG. Moreover, you may supply a chemical | medical solution from the front direction with respect to an end surface like 63b.

Next, the second end surface cleaning apparatus 70 in FIG. 6B will be described with reference to FIG.
The glass substrate G that has passed through the first end surface cleaning device 60 is put into the second end surface cleaning device 70, and the chemical solution of the previous process is washed away by the second end surface cleaning jigs 64a and 64b.

FIG. 7C shows a part of the end surface of the glass substrate in the second end surface cleaning apparatus 70.
In the second cleaning step, the magnetic foreign substance chelated to the surface cleaning device in the subsequent process is washed away by the rinse liquid, and the pH of the acidic chemical liquid adhering to the glass substrate is lowered, and the acidic chemical liquid is brought into the subsequent process. It is necessary to suppress this.

  As shown in FIG. 7C, the second end surface cleaning jig 64 has a cleaning nozzle 64 provided to face the end surface of the glass substrate G so as to have a predetermined angle. First, the end surface is washed away by the first rinse liquid discharged from the washing nozzle 64a. As the first rinsing liquid, one having a pH equivalent to that of the chemical liquid used in the first cleaning step was used. After the chemical solution adhering from the first cleaning step is washed away by the first rinse solution, the end surface of the glass substrate is washed away using pure water as the second rinse solution. Thereby, it can prevent bringing an acidic chemical | medical solution into the surface cleaning process of a post process. Moreover, the magnetic foreign material is reliably washed away by using a chemical solution having a pH equivalent to that in the first cleaning step as the first rinse solution.

  In the present embodiment, a cleaning nozzle that discharges the rinsing liquid from the main surface side to the end surface side is provided on the main surface side of the glass substrate G, and the cleaning nozzle that also discharges the rinsing liquid on the front side of the end surface May be provided.

In the method for producing a glass substrate for display according to the present invention, it is considered preferable to form a complex after setting the number of valence electrons of Fe to Fe ²⁺ . It added to the acidic chemical | medical solution used in 1 end surface washing | cleaning apparatus.

Regarding the stability of the complex, Fe ³⁺ has higher stability than Fe ^{2+ in the} number of valence electrons of iron. However, in a state where the separated iron component attached to the glass end face is in Fe ³⁺ , when the iron component separated from the end face cannot be completely chelated, the magnetic foreign matter remaining on the glass substrate is removed by Fe in the rinsing step described above. Compared to ²⁺ , it is passivated on the surface of the glass substrate and reattachment is likely to occur.
Therefore, in the present invention, in the rinsing step of removing the complex of magnetic foreign substances from the glass substrate before reducing the possibility that the magnetic foreign substances remain without being chelated and transported to the surface cleaning process, Even if the pH is shifted from acidic to neutral, foreign matter is prevented from reattaching to the surface of the glass substrate and being passivated.
In other words, in the present invention, the iron foreign matter constituting the magnetic foreign matter is reduced to Fe ²⁺ , thereby suppressing reattachment due to passivation on the glass surface compared to Fe ³⁺ even by the cleaning step of the present invention. There is an effect that it is possible.

The chelating agent of the present invention is preferably a chelating agent that performs bidentate coordination or more.
Specifically, it is preferable to have a molecular structure at a distance of 3 mm or less in the xyz axis direction from the hexacoordinate iron ion center of the Fe octahedron.

  As a specific example, the chemical solution having the chelating effect is salicylic acid, phthalic acid, glyoxylic acid, oxalic acid, fumaric acid, maleic acid, malonic acid, succinic acid, gluconic acid, trans-aconitic acid, tartalonic acid, lactic acid, pyruvin. Organic acids such as acid, citric acid, isocitric acid, glycolic acid, malic acid, tartaric acid. Aminocarboxylic acids such as nitrilotriacetic acid, ethylenediaminetetraacetic acid, hydroxyethylethylenediaminetriacetic acid, and diethylenetriaminepentaacetic acid; One or more selected from amino acids such as serine, aspartic acid, glutamic acid, and cysteine are used.

  As mentioned above, although embodiment of the manufacturing method of the glass substrate of this embodiment was described 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, various improvement and a change are carried out. Also good.

Examples of the present invention will be described in detail below.
First, the magnetic abrasive used in the polishing process of the present invention is a ferrite-based magnetic body, the particle shape is an indefinite shape having a corner, and the average particle diameter is 5 μm or more and 10 μm or less, Abrasive grains made of a magnetic material having a maximum magnetic flux density of 1.3 T and a maximum permeability of 3.0 H / m were prepared. Next, polishing media were prepared by mixing the prepared abrasive grains and water. As an example, magnetic abrasive grains and water may be mixed so that the concentration of abrasive grains in the polishing media is 85% or more.

  In this example, the concentration of the magnetic fluid was controlled using wt% in consideration of the ease of management and mass production applicability, but the concentration of the magnetic fluid should be controlled using vol%. You can also. The conversion between wt% and vol% can be calculated based on the bulk specific gravity of the magnetic abrasive grains and the density of water 1 g / cm 3. In the above comparative examples and examples, in consideration of evaporation of water from the magnetic fluid during polishing, the evaporated water is replenished to the magnetic fluid. Specifically, a magnetic fluid for supply in which magnetic abrasive grains and water were mixed was supplied to the wheel at a predetermined interval. The magnetic fluid for supply is supplied in a state where the concentration is lower than that of the magnetic fluid held on the wheel and the fluidity is high.

On the end surface of the glass substrate G obtained by the above polishing process, magnetic foreign substances made of magnetic abrasive grains adhere to the boundary portions B and C shown in FIG.
The end surface of the glass substrate G was washed with an acidic chemical solution described in the following examples and evaluated. The evaluation results are shown in Table 1.

(Experiment 1)
Each organic acid chemical was adjusted to a concentration of 2 wt%. When rinsing, the work was performed so that the pH did not become 2 or more.
After processing with magnetic abrasive grains, the end face was cleaned in the following steps.
1) Injection of the above chemical solution with a nozzle, 2) Disc sponge in which the chemical solution is immersed, 3) Rinse by injection of the chemical solution with a nozzle, 4) Rinse by injection of pure water. In Examples and Comparative Examples, a glass substrate having a thickness of 0.5 mm was used.

  The evaluation method was performed by peeling the foreign matter remaining on the end face of the glass substrate with an adhesive jig and measuring the amount of adhesion per unit area. Specifically, regarding the remaining area ratio of the foreign matter remaining on the glass substrate end surface, the cellophane tape is applied to the center of each of the four side end surfaces of the glass substrate of each sample, the cellophane tape is peeled off, and the surface of the peeled cellophane tape Were observed using an optical microscope equipped with a CCD imaging device. In addition, the cellophane tape was affixed on the thickness direction full length (from the B point of FIG. 5 to the C point) of the process area | region of the end surface of a glass substrate.

  The observation area by the optical microscope was an area of 0.75 mm which is a distance from point B to point C on the end face of the glass substrate in FIG. 5 × 0.75 mm in the length direction of the glass substrate. The number of foreign matters in this region was counted and evaluated.

  Moreover, it evaluated also about the foreign material adhering to the main surface (front and back) of the glass substrate after a washing | cleaning process. Specifically, the amount of foreign matter adhering to the front and back surfaces of the glass was measured using a glass substrate surface inspection device (GI4830 manufactured by Hitachi High-Tech Electronics Engineering). As measurement conditions, measurement was performed under the condition of detecting polystyrene standard particles of 1 μm or more.

  As shown in Table 1, with respect to the end face state of the glass substrate after cleaning, surface observation with a laser microscope was performed at points A, B, and C shown in FIG. 5 to evaluate the cleaning effect. The pH, reducing effect, and chelating effect conditions were scaled based on chemical properties.

  In the examples and comparative examples of Table 1, the acid dissociation constant (pKa) is indicated as ◎ when pH is 4.4 or less, ◎ when pH is 4.4 to 6, and × when pH is less than 6. In addition, the reducing power was evaluated as ◎ for -0.35 V or less, ◎ for -0.35 V to -0.05 V, and x for -0.05 V or more from the electrode potential of the standard hydrogen electrode.

  Regarding the cleaning effect, the case where the number of end face particles after cleaning was less than 150 was set as “cleaning effect: high”, and the case where it was less than 300 was set as “cleaning effect: present”. Moreover, the case where it was 300 or more was made into "the cleaning effect: nothing".

  If there is no foreign matter exceeding 300 in the observation area, the yield is not reduced due to the presence of iron-based foreign matter in the display manufacturing process. There was no problem even in the TFT panel manufacturing process in which the influence of iron-based foreign matters is a concern. Further, no foreign matter exceeding 1 μm was detected by the glass substrate surface inspection apparatus from a glass substrate having no foreign matter exceeding 300 in the observation area.

  As a result of the above Examples and Comparative Examples, a high cleaning effect could be confirmed by using organic acid acidity, oxalic acid having a reducing ability, and tartaric acid having a high chelate value. In Example 4, a particularly high cleaning effect was obtained.

  From the above examples, it is preferable to use a chemical solution containing a carboxyl group of an organic acid and adjust the chemical solution so as to have a pH at which at least a part of the carboxyl group is ionized. More preferably, it is preferable to use a chemical solution having a plurality of carboxyl groups, adjusted so that the carboxyl groups at a plurality of locations are ionized and lower than the pH of the glass isoelectric point.

As described above, in one aspect of the present invention, by making the pH less than 2, preferably less than 1.6, the electrostatic interaction between the glass surface and the magnetic foreign material is reduced to reduce the iron that is the magnetic foreign material. Ionization is caused to float from the end face of the glass substrate, and ionized iron is chelated to prevent reattachment to the glass. Then, it is removed by washing in a subsequent rinsing step. Also in the rinsing step, the chemical solution used for rinsing may have the same pH as the chemical solution used for reduction or chelation. For example, the chemical solution used for rinsing is preferably pH 3 or lower, or within a pH range of 2-3.
Even in an acidic chemical solution, if an acid having strong oxidizing power such as concentrated nitric acid or concentrated sulfuric acid is used, the surface of iron is passivated, and thus an acid having strong oxidizing power is not preferable.

Moreover, in the manufacturing method of the glass substrate of this invention, it is preferable to form a complex after setting the valence electron number of iron to Fe ^<2+> . Regarding the stability of the complex, Fe ³⁺ has higher stability than Fe ^{2+ in the} number of valence electrons of iron. However, when reducing the iron component adhering to the glass end face to Fe ³⁺ , if the iron component distant from the end face could not be chelated completely, it was passivated and reattached on the surface of the glass substrate in the rinsing process. There is a risk that.
Therefore, in the present invention, in the rinsing step of removing the iron complex and removing other foreign substances, the iron foreign substances are reduced to Fe ²⁺ even if the pH of the cleaning liquid is shifted from acidic to neutral for rinsing. As a result, passivation on the glass surface can be suppressed as compared with Fe ³⁺ , and iron foreign matter can be prevented from reattaching to the surface of the glass substrate. That is, the iron foreign matter adhering to the end face is prevented from entering the surface.

Moreover, it is preferable that the chemical | medical solution which has the said reduction effect contains an acidic chemical | medical solution with a standard oxidation-reduction potential of -0.35V or less at least. The reduction of Fe ³⁺ ions are needed -0.77V, but can be lowered reduction potential of Fe ³⁺ ions by the use of a chemical solution with a chelating effect. That is, a reduction effect can be obtained even at the set potential or higher, and end face cleaning becomes possible. In the above embodiment, oxalic acid is used. In addition, since -0.77V is required for reduction | restoration of Fe3 ⁺ ion, in order to obtain higher detergency, you may use the chemical | medical solution which has the standard oxidation potential of -0.8V or less acidic chemical | medical solution.

  Moreover, as a chelating agent, the chelating agent which performs bidentate coordination or more is preferable. Specifically, it is preferable to have a molecular structure having an electron donating group at a distance of 3 mm or less in the xyz-axis direction from the hexacoordinate iron ion center of the Fe octahedron. As a specific example, the chemical solution having the chelating effect is salicylic acid, phthalic acid, glyoxylic acid, oxalic acid, fumaric acid, maleic acid, malonic acid, succinic acid, gluconic acid, trans-aconitic acid, tartalonic acid, lactic acid, pyruvin. Organic acids such as acid, citric acid, isocitric acid, glycolic acid, malic acid, tartaric acid. Aminocarboxylic acids such as nitrilotriacetic acid, ethylenediaminetetraacetic acid, hydroxyethylethylenediaminetriacetic acid, and diethylenetriaminepentaacetic acid; One or more selected from amino acids such as serine, aspartic acid, glutamic acid, and cysteine are used.

  The end face is preferably washed with physical washing. In order to surely remove the foreign matter away from the end surface of the glass substrate, a cleaning jig for cleaning the end surface by contacting the end surface of the glass substrate while containing or holding a chemical solution may be used. For example, a disc-shaped sponge or brush is preferable.

  As a glass substrate manufactured using this invention, it is not limited to a display use, You may apply to manufacture of another glass substrate. Moreover, you may apply to the thin glass substrate wound up by roll shape. In the glass substrate wound up in a roll shape, both side portions of the formed glass sheet are cut, processed on the cut surfaces of the both side portions, and processing and washing are performed on the cut surfaces.

  In the above embodiment, the polishing apparatus 40 described in the embodiment and FIG. 4 is used to perform mirror polishing of the end face by the polishing media held between the magnetic bodies 36a and 36b attached to the rotary shaft 35. Depending on the form, it can also be used for cleaning glass polished by bringing the magnetic abrasive grains into contact with the end face of the glass substrate. FIG. 8 shows another type of polishing apparatus 180. A polishing slurry 187 containing a magnetic material is supplied from a supply unit 184 to a groove of a rotating wheel 182 having a groove (not shown), and the polishing slurry 187 containing a magnetic material is held and moved by a magnetic body 185 provided on the rotating wheel. . The polishing slurry 187 containing a magnetic material comes into contact with the end surface of the glass plate as it rotates and is collected by the collection unit 186.

  The glass plate and glass substrate produced using the present invention are not limited to display applications, but can be suitably used for display applications. The glass substrate for display manufactured using the present invention is not limited to the glass substrate for driving TFT panel, and includes, for example, a glass substrate for color filter, a glass substrate for cover glass, and the like. Further, the display device is not limited to a liquid crystal display or an organic EL display, and may be used for other displays.

Claims (12)

  In the method of manufacturing a glass plate having a polished processing unit, the processing unit is polished by contacting a polishing slurry containing a magnetic material, and a cleaning liquid is supplied to the polished processing unit, so that the processing unit A method for producing a glass plate, wherein the surface and the surface of the magnetic material attached to the processing unit are charged to the same polarity, the processing unit and the magnetic material are repelled, and the magnetic material is transferred to a cleaning liquid. A forming step of forming a glass sheet from molten glass, a cutting step of cutting the glass sheet to form a glass substrate, and an end surface of the glass substrate are brought into contact with a polishing slurry containing a magnetic body held by a magnetic body End surface processing step for mirror polishing,
A cleaning step of cleaning the iron-based fine particles caused by the magnetic substance brought into contact with the end surface in the mirror polishing step using an acidic chemical solution having a pH of 2 or less;
In the method of manufacturing a glass substrate, the cleaning step includes reducing Fe ³⁺ constituting the iron-based fine particles into Fe ²⁺ ions to form a complex by bidentate coordination or more of the Fe ²⁺ ions.   The said acidic chemical | medical solution is a manufacturing method of the glass substrate of Claim 2 which consists of 2 or more types of chemical | medical solutions containing the chemical | medical solution which has a chelate effect.   The said cleaning process is a manufacturing method of the glass substrate of Claim 2 or 3 provided with the cleaning jig for contacting the said end surface and physically cleaning the said end surface.   5. The chemical solution having a chelate effect according to claim 2, wherein the chemical solution has a molecular structure having an electron donating group at a distance of 3 mm or less in the xyz axis direction from the hexacoordinate iron ion center of Fe octahedron. A method for producing a glass substrate.   The chemical solution having the chelating effect is salicylic acid, phthalic acid, glyoxylic acid, oxalic acid, fumaric acid, maleic acid, malonic acid, succinic acid, gluconic acid, trans-aconitic acid, tartalonic acid, lactic acid, pyruvic acid, citric acid, From organic acids such as isocitric acid, glycolic acid, malic acid and tartaric acid, aminocarboxylic acids such as nitrilotriacetic acid, ethylenediaminetetraacetic acid, hydroxyethylethylenediaminetriacetic acid and diethylenetriaminepentaacetic acid, amino acids such as serine, aspartic acid, glutamic acid and cysteine The manufacturing method of the glass substrate of Claim 4 or 5 made into 1 or more types selected.   The manufacturing method of the glass substrate of Claim 6 using the chemical | medical solution selected in the said washing | cleaning process from oxalic acid, tartaric acid, or a citric acid, and the density | concentration was adjusted to 0.5 wt% or more.   The first rinsing step and the second rinsing step are included in the subsequent steps of the washing step, a chemical solution having a pH of 3 or less is used in the first rinsing step, and a chemical solution having a pH of more than 3 is used in the second rinsing step. The manufacturing method of the glass substrate in any one of. In the method for manufacturing a glass substrate for display, a forming step of forming a glass sheet from molten glass, a cutting step of cutting the glass sheet to form a glass substrate,
An end surface processing step for mirror polishing by bringing a polishing slurry containing a magnetic body held by a magnetic body into contact with the end surface of the glass substrate; and a cleaning step for cleaning with the end surface acidic chemical solution,
The end face processing step includes a magnetic field forming unit provided with a first magnetic body and a second magnetic body that are arranged at an interval in the axial direction of the rotary shaft and rotate together with the rotary shaft, the magnetic abrasive grains, and the liquid The magnetic body in the polishing slurry using a polishing wheel comprising a polishing slurry comprising a magnetic body held by a magnetic field formed between the first magnetic body and the second magnetic body And adjusting the concentration of the magnetic material to 85% or more and contacting the end face of the glass substrate with the magnetic body in a state where the rotating shaft is rotated,
In the cleaning step, in order to remove the iron-based fine particles caused by the magnetic substance attached to the glass end surface in the end surface treatment step, Fe iron constituting the iron-based fine particles using an acidic chemical solution having a pH of 1.6 or less. ^A method for producing a glass substrate for a display, wherein ³⁺ is reduced to Fe ²⁺ ions, and two or more of the Fe ions are coordinated to form a complex. The end surface processing step has a grinding process for grinding the end surface of the glass substrate before the mirror polishing process,
The grinding process includes a first grinding process for grinding an end surface of the glass substrate using a first grinding wheel in which abrasive grains are hardened with a first binder.
After the first grinding process, the end surface of the glass substrate is ground using a second grinding wheel in which abrasive grains are hardened with a second binder having lower hardness and rigidity than the first binder. The manufacturing method of the glass substrate of Claim 9 which has 2 grinding processes. The first binder is a metal binder and the second binder is a resin binder;
The manufacturing method of the glass substrate of Claim 10. In the grinding treatment, the end face of the glass substrate is ground so that the arithmetic average roughness Ra specified by JIS B 0601-1994 is 0.2 μm or less,
12. The method of manufacturing a glass substrate according to claim 10, wherein in the mirror polishing process, an end surface of the glass substrate is polished so that the arithmetic average roughness Ra is less than 0.01 μm.

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