TW201319231A - Method for producing glass substrate - Google Patents

Abstract

The present invention relates to a method for producing a glass substrate, wherein at least one main surface of a glass substrate main body is polished with a polishing liquid which is obtained by dispersing abrasive grains in a dispersion medium that is composed of a liquid medium other than water, said dispersion medium substantially containing no water or containing some water (provided that the water content in the dispersion medium is 85% by mass or less).

Description

Method for manufacturing glass substrate

The present invention relates to a method of manufacturing a glass substrate. More specifically, it relates to a method for producing a high-strength glass substrate suitable for a glass substrate used in a flat panel display (FPD) such as a liquid crystal display (LCD).

A flat panel display (FPD) such as a liquid crystal display (LCD) is used as an information terminal such as a personal computer or a mobile phone, or a display device such as a liquid crystal television.

The glass substrate for FPD is required to be lighter and thinner as the size of the machine is reduced. However, if the thickness of the glass substrate is made small, the strength is lowered, and cracking is likely to occur due to dropping or the like. Therefore, it is required to have a glass substrate which is thinned and has high strength and which can provide an excellent protective function.

The glass substrate for FPD is formed into a plate shape by a manufacturing method called, for example, a float technique, and the glass substrate is polished by, for example, a polishing tool that performs rotation and revolution, and the surface is slightly uneven. The undulation is removed to produce a thin plate having a specific thickness (for example, 0.4 to 1.1 mm) which satisfies the flatness required for the glass substrate for FPD (for example, refer to Patent Document 1).

When such a thin glass substrate has irregularities or scratches on its surface, it is inferior in appearance, and it is easy to cause cracks or cracks due to external pressure from the above-mentioned portions, and sufficient strength cannot be obtained. Therefore, for such a thin glass substrate, the surface is polished with high precision to obtain higher strength.

For example, Patent Document 1 discloses that a colloidal cerium oxide aggregate obtained by connecting condensed colloidal cerium oxide particles is dispersed in water. Slurry, a surface grinding method for polishing the surface of a glass substrate. Further, Patent Document 2 discloses a polishing liquid composition pair using cerium oxide particles having a specific ratio of an area ratio of a projected area of the cerium oxide particles to a maximum inscribed circular area of the cerium oxide particles. The step of polishing the glass substrate.

Although the glass substrate is surface-treated by the above method, the unevenness or undulation of the surface of the glass substrate can be removed to some extent, but the effect of improving the strength of the glass substrate after polishing is not necessarily sufficient. Therefore, a method of improving the strength of a glass substrate with higher precision has been sought.

As a method of strengthening the glass substrate, for example, a method of forming a compressive stress layer on the surface of a glass substrate to increase the strength is known. In the chemical strengthening treatment method, the glass substrate is immersed in a molten salt containing an alkali metal ion, and the alkali metal ions in the glass on the surface of the substrate are replaced with alkali metal ions in the molten salt, thereby forming a compressive stress on the surface of the glass substrate. The method of the layer is widely used as a method for improving the strength of a glass substrate (for example, refer to Patent Document 3).

Since the chemical strengthening treatment method does not require the thickness of the glass substrate itself, it is particularly suitable for the improvement of the strength of the thin glass substrate, but there is a problem that the equipment required for the treatment is large in size and poor in cost.

In addition, a glass substrate for a display such as a liquid crystal display device is often used as a film of a metal or a metal oxide on the surface, and if an alkali metal is contained in the glass, alkali metal ions are diffused into the film to deteriorate the film properties. Therefore, as a glass substrate for a display, an alkali-free glass which does not substantially contain an alkali metal is used, and the above-mentioned chemical strengthening cannot be applied to such a glass substrate. The problem of handling.

[Previous Technical Literature] [Patent Literature]

Patent Document 1: Japanese Patent Laid-Open Publication No. 2010-250915

Patent Document 2: Japanese Patent Laid-Open Publication No. 2008-13655

Patent Document 3: Japanese Patent Laid-Open Publication No. 2010-202514

The present invention has been made to solve the above problems, and an object of the invention is to provide a glass substrate manufacturing method which can obtain a glass substrate which is improved in strength with high precision for a glass substrate which is applied to a liquid crystal display device or the like.

The method for producing a glass substrate of the present invention is dispersed in a dispersion medium containing a liquid medium other than water containing no water or containing water (wherein the content of water in the dispersion medium is 85% by mass or less) The polishing liquid of the abrasive grains is polished on at least one main surface of the glass substrate body.

In the method for producing a glass substrate of the present invention, it is preferred that the content of water in the dispersion medium is from 3 to 60% by mass.

In the method for producing a glass substrate of the present invention, it is preferred that the content of water in the dispersion medium is less than 3% by mass.

In the method for producing a glass substrate of the present invention, it is preferred that the liquid medium other than the water is an organic solvent.

In the method for producing a glass substrate of the present invention, the above organic solvent is preferred. The agent is a monohydric or polyhydric alcohol.

In the method for producing a glass substrate of the present invention, it is preferred that the organic solvent is a hydrocarbon, an ether, an ester or a ketone.

In the method for producing a glass substrate of the present invention, it is preferred that the liquid medium other than the water is selected from the group consisting of methanol, ethanol, n-propanol, isopropanol, n-butanol, ethylene glycol, propylene glycol, n-hexane, and octane. At least one of the group consisting of alkane, ethyl acetate, methyl ethyl ketone, toluene and diethyl ether.

In the method for producing a glass substrate of the present invention, it is preferable that the abrasive grains are at least one metal oxide selected from the group consisting of cerium oxide, aluminum oxide, cerium oxide, titanium oxide, zirconium oxide, and manganese oxide. Microparticles.

In the method for producing a glass substrate of the present invention, it is preferred that the abrasive grains are particles having an average particle diameter of 5 to 500 nm.

In the method for producing a glass substrate of the present invention, it is preferable that the content of the abrasive grains contained in the polishing liquid is 0.1 to 40% by mass based on the total mass of the polishing liquid.

In the method for producing a glass substrate of the present invention, preferably, the polishing liquid is supplied to the polishing pad, and the polished surface of the glass substrate main body is brought into contact with the polishing pad, and the glass substrate is opposed to the glass substrate. The surface of the body is ground.

In the method for producing a glass substrate of the present invention, it is preferable that the glass substrate is a glass substrate containing an alkali-free glass.

In the method for producing a glass substrate of the present invention, it is preferable that the glass substrate has a thickness of 0.1 to 5 mm.

According to the present invention, a glass substrate having an increased strength higher than the previous precision can be obtained.

Hereinafter, an embodiment of the present invention will be described by taking a method of manufacturing a glass substrate for use in an FPD application such as an LCD.

The present invention is not limited to the embodiments, and is included in the present invention as long as it conforms to the gist of the present invention.

The method for producing a glass substrate of the present invention can be carried out by supplying a polishing liquid to a polishing pad and bringing the polished surface of the glass substrate into contact with the polishing pad, and the glass substrate is moved by the relative movement therebetween. The surface to be polished is ground.

As the polishing apparatus used in the above polishing, a conventionally known polishing apparatus can be used. Fig. 1 is a view showing an example of a polishing apparatus which can be used in the method for producing a glass substrate of the present invention.

In the grinding apparatus 10 shown in Fig. 1, the grinding platen 1 is arranged to be supported in a manner rotatable about its vertical axis C1, which is driven by the platen driving motor 2 Rotate the drive in the direction indicated by the arrow. A known polishing pad 3 is adhered to the upper surface of the polishing platen 1.

On the other hand, the substrate holding member (carrier) 5 that holds the object to be polished, such as a glass substrate, is adsorbed on the lower surface of the polishing platen 1 at a position offset from the axis C1, so as to be rotatable about its axis C2. It can be supported in such a manner that it can move in the direction of the axis C2. The substrate holding member 5 is configured to be driven by a workpiece driving motor (not shown) or by a rotational moment received from the polishing platen 1 in a direction indicated by an arrow. Substrate holding member 5 The lower surface, that is, the surface facing the polishing pad 3, holds the glass substrate body 4 as an object to be polished. The glass substrate body 4 is pressed against the polishing pad 3 with a specific load.

Further, a drip nozzle 6 or the like is provided in the vicinity of the substrate holding member 5, and the polishing liquid 7 sent from a storage tank (not shown) is supplied to the polishing platen 1.

When polishing is performed by the polishing apparatus 10, the polishing pad 3 and the polishing pad 3 adhered thereto, the substrate holding member 5, and the glass substrate body 4 held on the lower surface thereof are driven by the platen motor 2 and When the workpiece drive motor is rotationally driven around the respective axes, the polishing liquid 7 is supplied from the drip nozzle 6 or the like to the surface of the polishing pad 3, and the glass substrate main body 4 held by the substrate holding member 5 is pressed against the substrate. Grinding pad 3 on. Thereby, the surface to be polished of the glass substrate body 4, that is, the surface facing the polishing pad 3 is polished.

The polishing liquid 7 is a slurry in which abrasive grains are dispersed in a dispersion medium. In the present invention, as the dispersion medium, a dispersion medium containing a liquid medium other than water which does not substantially contain water or contains water of a specific limit or less is used.

By polishing the surface to be polished of the glass substrate body by using such a polishing liquid 7, it is possible to suppress penetration of moisture in the polishing liquid into the inside of the glass substrate body during polishing, and it is possible to reduce the amount of moisture contained in the glass substrate body. Therefore, the strength of the glass substrate obtained after the polishing can be improved with high precision.

The dispersion medium is used to stably disperse the abrasive grains, and to add a liquid medium in which any of the components described later are dispersed and dissolved as needed. The liquid medium in the present invention refers to an organic compound or water which is liquid at normal temperature, and may be a mixture of one or more of them.

The organic compound as the liquid medium is not limited to a low molecular compound generally called an organic solvent, and may be a polymer compound (for example, a polymer compound called oil) which is liquid at normal temperature. The boiling point of the liquid medium is preferably 60 ° C or higher, but is not limited thereto.

The dispersion medium of the polishing liquid used in the present invention is a liquid medium containing no water or water containing water, and in the case of a water-containing dispersion medium, the content of water in the dispersion medium is 85% by mass. the following.

In the present invention, the dispersion medium which does not substantially contain water means that the content ratio of water is less than 3% by mass. Generally, it means a dispersion medium which is used without adding a substantial amount of water to a liquid medium other than water. In addition, hereinafter, a liquid medium other than water is simply referred to as a liquid medium unless otherwise specified.

In the case where the dispersion medium of the present invention contains water, it is preferably a homogeneous mixture in which the liquid medium and water are mutually dissolved. When the liquid medium and the water do not dissolve each other, for example, if water is not dissolved in the dispersion medium, water may easily enter the inside of the glass substrate during the polishing process, and the strength of the glass substrate obtained after the polishing may not be sufficiently improved. Hey. In the case of a dispersion medium which does not substantially contain water, it is also preferred that a small amount of water existing in the range of less than 3% by mass is dissolved in the liquid medium.

If the content ratio of the water in the dispersion medium exceeds 85% by mass based on the total mass of the dispersion medium, even if the water and the liquid medium dissolve in a uniform dispersion medium, water is easily allowed to enter during the polishing of the glass substrate. Inside the glass substrate, the strength of the glass substrate obtained after polishing cannot be sufficiently improved. In the case of a dispersion medium containing water, the water in the dispersion medium The total content of the content ratio with respect to the dispersion medium is preferably 60% by mass or less, and more preferably 20% by mass or less.

More preferably, the polishing liquid 7 is a polishing liquid having a water content of 80% by mass or less, more preferably 50% by mass or less based on the total mass of the polishing liquid.

The liquid medium is preferably an organic solvent having a boiling point of 40 ° C or higher, preferably 60 ° C or higher.

In an organic solvent, a hydrophilic organic solvent is easily mixed with a relatively large amount of water to form a homogeneous mixture. Therefore, the hydrophilic organic solvent is suitable as a liquid medium in a dispersion medium containing water. Further, even if the hydrophilic organic solvent is not substantially water-containing, that is, the content ratio of water is less than 3% by mass, it can be used as a dispersion medium which does not substantially contain water.

On the other hand, since the organic solvent having a high hydrophobicity has a small amount of water which can be uniformly mixed therein, it is usually used as a liquid medium which is a substantially non-aqueous dispersion medium.

In addition, the organic solvent having a certain degree of hydrophilicity can be used as a liquid medium in a water-containing dispersion medium when the water content is less than or equal to the solubility of the water and the water content is 3% by mass or more. Further, in the case where the water content is not substantially contained, that is, when the water content ratio is less than 3% by mass, it can be used as a liquid medium in a dispersion medium which is substantially free from water.

As the liquid medium, for example, an organic solvent such as a monohydric or polyhydric alcohol, a hydrocarbon, an ether, an ester or a ketone can be preferably used. Further, as the liquid medium, a mixture of two or more kinds of organic solvents having compatibility may be used.

Among these organic solvents, a low carbon number one alcohol or a polyol is hydrophilic The organic solvent, as described above, is suitable as a liquid medium in a dispersion medium containing water or a dispersion medium which is substantially free of water. As the monohydric or polyhydric alcohol, an alkanol having a carbon number of 4 or less or a monoalkylene glycol or dialkylene glycol having a carbon number of 2 to 8 is more preferable.

On the other hand, hydrocarbons such as aliphatic hydrocarbons, alicyclic hydrocarbons, and aromatic hydrocarbons are hydrophobic, and as described above, they are suitable as a liquid medium which is a substantially non-aqueous dispersion medium. As the hydrocarbon, a saturated aliphatic hydrocarbon having 5 to 12 carbon atoms is more preferable.

As the ether, an alkylene glycol monoalkyl ether or an alkylene glycol dialkyl ether having a carbon number of 8 or less is preferable; and as the ester, an aliphatic carboxylic acid alkyl group having a carbon number of 8 or less is preferable. ester. Further, aromatic hydrocarbons such as toluene, dialkyl ethers such as diethyl ether, and dialkyl ketones such as methyl ethyl ketone are also preferred.

Specific examples of the organic solvent include methanol, ethanol, n-propanol, isopropanol (hereinafter referred to as IPA), n-butanol, tert-butanol, pentanol, hexanol, heptanol, and octane. Alcohol, decyl alcohol, lauryl alcohol and other carbon atoms of 1 to 12; unsaturated alcohols such as allyl alcohol, crotyl alcohol and methyl vinyl alcohol; cyclopentanol, cyclohexanol, benzyl alcohol, phenylethanol a cyclic alcohol; a glycol such as ethylene glycol, propylene glycol, diethylene glycol or dipropylene glycol; a trihydric or higher polyol such as glycerol or pentaerythritol; diethyl ether, dipropyl ether, dibutyl ether, ethyl ethylene Ether, anisole, diphenyl ether, two Ethers such as alkane, tetrahydrofuran, acetal, propylene glycol monomethyl ether, propylene glycol monoethyl ether; esters of ethyl formate, methyl formate, methyl acetate, ethyl acetate, butyl acetate, benzoate, oxalate, etc. ; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, 2-pentanone, 3-pentanone, 2-hexanone, 2-heptanone, cyclohexanone, acetophenone; pentane, a saturated aliphatic hydrocarbon such as hexane, heptane, octane, decane, decane, undecane, dodecane, methylpentane, dimethylbutane, trimethylpentane or isooctane; An unsaturated aliphatic hydrocarbon such as hexene, heptene or octene; an alicyclic hydrocarbon such as cyclopentane, cyclohexane, methylcyclohexane, cyclohexene, bicyclohexane or decahydronaphthalene; Aromatic hydrocarbons such as toluene, xylene, ethylbenzene, cumene, mesitylene, dodecylbenzene, naphthalene, methylnaphthalene, styrene; methyl chloride, dichloromethane, chloroform, dichloroethane , halogenated hydrocarbons such as trichloroethane, tetrachloroethylene, dichloropropane, allyl chloride, chlorobutane, chlorobenzene, ethyl bromide, dibromoethane; formic acid, acetic acid, propionic acid, caproic acid, oleic acid Organic acids; Methane, nitroethane, nitrobenzene, acetonitrile, methylamine, dimethylamine, ethylamine, diethylamine, allylamine, aniline, dimethylaniline, toluidine, pyrrole, piperidine, pyridine, methyl Nitrogen compounds such as pyridine, quinoline, ethylenediamine, diethylenetriamine, formamide, methylformamide, dimethylformamide, pyrrolidone, caprolactam, etc.; thiophene, dimethylene Sulfur compounds such as hydrazine.

Among these, from the viewpoints of ease of dispersion of the abrasive grains or obtaining excellent polishing characteristics, it is preferably used selected from the group consisting of methanol, ethanol, n-propanol, isopropanol, n-butanol, and ethylene glycol. At least one organic solvent selected from the group consisting of propylene glycol, n-hexane, octane, ethyl acetate, methyl ethyl ketone, toluene and diethyl ether.

Further, the liquid medium is not limited to the above-described organic solvent as long as it has a low water content ratio. For example, petroleum solvents such as petroleum ether, kerosene, and gasoline, and natural fats and oils may be used. Low molecular polymer, polyoxygenated oil, and the like.

As the abrasive particles dispersed in the dispersion medium, it can be self-known in the abrasive grains. Suitable choice. Specifically, it is preferably at least one selected from the group consisting of cerium oxide, aluminum oxide, ceria, zirconia, titania, tin oxide, Microparticles of metal oxides such as zinc oxide, manganese oxide, and cerium oxide, fine particles of nitrides such as boron nitride, tantalum nitride, and titanium nitride, fine particles of carbides such as tantalum carbide and boron carbide, polyethylene, polypropylene, and poly Fine particles of resin such as styrene, acrylic resin, phenol resin, polyester, polyoxyn resin, fine particles of metals such as gold, silver, and copper, fine particles of carbon such as graphite and diamond, sodium carbonate, calcium carbonate, calcium sulfate, and chlorine. Microparticles of salt such as sodium and potassium chloride.

Among these, from the viewpoint of obtaining higher polishing precision and polishing speed, it is preferable to use a group selected from the group consisting of cerium oxide, aluminum oxide, cerium oxide, zirconium oxide, titanium oxide, and manganese oxide. At least one metal oxide microparticle.

As the cerium oxide, a manufacturer can be used by a known method. For example, colloidal cerium oxide obtained by hydrolyzing a cerium alkoxide such as ethyl decanoate or methyl decanoate by a sol-gel method can be used. Further, colloidal cerium oxide obtained by ion-exchange of ceric acid salt such as sodium citrate or smoked cerium oxide obtained by gas phase synthesis of cerium tetrachloride in a flame of oxygen and hydrogen can be used.

Further, as the cerium oxide particles, those having a concave-convex shape on the surface may be used.

Likewise, colloidal alumina can also be preferably used. Further, cerium oxide, zirconium oxide, titanium oxide, tin oxide, or zinc oxide produced by a liquid phase method or a vapor phase method can also be preferably used. Among these, in terms of easily controlling the particle diameter and obtaining a high-purity product, colloidal cerium oxide is preferably used.

The average particle diameter of the abrasive grains is preferably in the range of 5 to 500 nm, more preferably in the range of 10 to 200 nm, in terms of polishing rate, polishing property, and dispersion stability. When the average particle diameter of the abrasive grains is less than 5 nm, the abrasive grains tend to aggregate in the polishing liquid, and a stable polishing liquid cannot be obtained. On the other hand, when the average particle diameter of the abrasive grains exceeds 500 nm, the damage to the surface to be polished of the glass substrate is large, and a smooth and high-quality surface cannot be obtained. That is, when polishing is performed using a polishing liquid containing cerium oxide particles having an average particle diameter of more than 500 nm, the surface of the polished glass substrate is likely to be scratched or strained, and the strength of the polished glass substrate is lowered. Hey.

Further, the average particle diameter of the abrasive grains in the present invention means an average particle diameter measured by a dynamic light scattering type particle size distribution meter. In the measurement, a sample having a suitable concentration range specified by the apparatus diluted with pure water or an organic solvent is used as a measurement sample to obtain an appropriate scattering and reflected light intensity. Specifically, a particle size analyzer "Microtrac UPA-ST150" (product name, manufactured by NIKKISO Co., Ltd.) is used as a measurement sample, and is used as a suitable concentration range specified by the device. The method uses a pure water or an organic solvent to dilute the abrasive particles.

The content ratio (concentration) of the abrasive grains in the polishing liquid can be appropriately set in consideration of the polishing rate, the uniformity of the polishing rate in the surface of the glass substrate, the dispersion stability, and the like, and is preferably relative to the polishing liquid in order to obtain sufficient polishing characteristics. The total mass is set to be 0.1% by mass or more and 40% by mass or less. When the content ratio of the abrasive grains is less than 0.1% by mass based on the total mass of the polishing liquid, the effect of improving the strength of the glass substrate by polishing cannot be sufficiently obtained, and if it exceeds 40 mass %, there is a reduction in dispersion. A more preferable content ratio is 1 to 20% by mass, and further preferably a content ratio of 5 to 10% by mass.

It is preferable that the polishing liquid used in the present invention contains the above-mentioned components in the above specific ratio, and is prepared by mixing the abrasive grains such as colloidal cerium oxide uniformly and uniformly mixing the components other than the above, but using the same. In the range in which the effect of the polishing can be stably obtained, the components in the polishing liquid may be unevenly distributed to some extent. Specifically, even when the specific gravity of the abrasive grains is high and the precipitate is precipitated in the polishing liquid, if the abrasive grains are supplied to the polishing machine at a fixed ratio by designing the supply method of the polishing liquid, the polishing pad can be maintained. In the state of the state of the fixed abrasive grains, even if the abrasive grains are not uniformly dispersed in the polishing liquid, the effect of polishing can be sufficiently obtained. Mixing may be carried out by a stirring mixing method generally used for producing a polishing liquid, for example, a stirring mixing method using an ultrasonic disperser, a homogenizer or the like. The polishing liquid used in the present invention is not necessarily supplied to the polishing site in such a manner that all of the constituent polishing components are mixed in advance. When the material is supplied to the polishing site, the polishing components may be mixed to form a composition of the polishing liquid.

The polishing liquid is preferably prepared by dissolving an organic solvent or water in a dispersion liquid such as colloidal cerium oxide in which the abrasive grains are uniformly dispersed, and adjusting the composition of the dispersion medium as appropriate. For example, as a commercially available colloidal cerium oxide, there may be a water-dispersed colloidal cerium oxide or an organic solvent-dispersed colloidal cerium oxide, and the slurry may be a commercially available water-dispersed colloidal cerium oxide or an organic solvent-dispersed colloidal cerium oxide. And manufacturing.

Specifically, for example, it can be formulated by dispersing colloidal cerium oxide in water. The organic solvent or a method of formulating water or the like in an organic solvent-dispersed colloidal cerium oxide, and a slurry obtained by dispersing cerium oxide abrasive grains in a dispersion medium containing a specific amount of water.

Further, a commercially available organic solvent-dispersed colloidal cerium oxide can be used as the polishing liquid in the present invention by adjusting its abrasive particle content as needed. Generally, a specific abrasive content of the slurry is prepared by formulating an organic solvent which is the same as the organic solvent contained in the organic solvent-dispersed colloidal ceria. However, the polishing liquid used in the present invention is not limited thereto, and an organic solvent different from the organic solvent contained in the organic solvent-dispersed colloidal cerium oxide may be blended.

By using the above-mentioned hydrophilic organic solvent, an organic solvent used in the case of preparing an organic solvent in a water-dispersed colloidal cerium oxide to prepare a polishing liquid, or a water prepared by dissolving water in an organic solvent-dispersed colloidal cerium oxide. In the case of a polishing liquid, the organic solvent disperses the organic solvent contained in the colloidal ceria to form a dispersion medium in which water and an organic solvent dissolve each other. In the organic solvent-dispersed colloidal cerium oxide, when the organic solvent contained in the organic solvent-dispersed colloidal cerium oxide is prepared as a different type of organic solvent to prepare a polishing liquid, the organic solvent preferably has compatibility.

The polishing liquid used in the present invention may suitably contain a surfactant, a chelating agent, a reducing agent, a viscosity-imparting agent or a viscosity adjusting agent, an anti-aggregating agent or a dispersing agent as long as it does not deviate from the gist of the present invention. , rust inhibitors, etc. When at least one of the optional components is used, the total amount of the optional components is preferably 10% by mass or less based on the polishing liquid.

The substrate holding member 5 can perform not only a rotational motion but also a linear motion. Further, the polishing platen 1 and the polishing pad 3 may be used as objects to be polished. The glass substrate body 4 is the same size or less. In this case, it is preferable to polish the entire surface of the surface to be polished of the glass substrate body 4 by moving the substrate holding member 5 and the polishing platen 1 relatively. Further, the polishing platen 1 and the polishing pad 3 may not be rotated, and for example, may be moved in one direction by a conveyor belt type.

By polishing the surface to be polished of the glass substrate body 4 in this manner, a glass substrate having improved strength with high precision can be obtained.

In addition, the polishing apparatus 10 is a polishing apparatus that polishes a single surface of the glass substrate main body 4 as the object to be polished as a surface to be polished. For example, the polishing apparatus 10 may be disposed on the lower surface of the glass substrate main body 4 in the same manner as the polishing apparatus 10 The double-sided simultaneous polishing apparatus of the polishing pad polishes the polished surface (both sides) of the object to be polished.

The conditions for polishing by the polishing apparatus 10 are not particularly limited, and pressing the substrate holding member 5 against the polishing pad 3 can further increase the polishing pressure and increase the polishing rate. The polishing pressure is preferably about 5 to 30 kPa, and is preferably about 5 to 15 kPa from the viewpoint of uniformity of polishing rate in the polishing surface, flatness, and polishing defects such as scratch prevention. The number of rotations of the polishing platen 1 and the substrate holding member 5 is preferably about 20 to 100 rpm, but is not limited thereto. In addition, the amount of the polishing liquid 7 to be supplied can be appropriately adjusted and selected depending on the composition of the surface to be polished or the composition of the polishing liquid, the respective polishing conditions, and the like. For example, when the glass substrate having a side of 50 mm is polished, Preferably, the supply amount is about 20 to 40 cm ³ /min.

As the polishing pad 3, a nonwoven fabric or a foamed polyamine group can be used. A polishing pad such as a formate or a porous resin or a non-porous resin. Further, in order to promote the supply of the polishing liquid 7 to the polishing pad 3, or to deposit a certain amount of the polishing liquid 7 on the polishing pad 3, the surface of the polishing pad 3 may be grooved in a lattice shape, a concentric shape, or a spiral shape. machining. Further, if necessary, the polishing pad conditioner may be brought into contact with the surface of the polishing pad 3 to polish the surface of the polishing pad 3 while being polished.

Further, in the above-described embodiment, a method of using a so-called flow type polishing apparatus for discharging the polishing liquid after one polishing is described as an example, but polishing to be supplied to the polishing pad may be used. The liquid was carried out in the form of a polishing apparatus of a so-called circulation type used for recycling after polishing.

As a polishing apparatus of the circulation type, for example, a polishing apparatus 20 including the following parts as shown in FIG. 2 can be used: a substrate holding member (carrier) 22 that holds the glass substrate body 21 as an object to be polished, a polishing platen 23, and a paste. The polishing pad 24 on the surface of the polishing platen 23, the storage tank 28 storing the polishing liquid 25, and the dropping nozzle 26 for supplying the polishing liquid 25 from the storage tank 28 to the polishing pad 24 using the polishing liquid supply unit 27.

The polishing apparatus 20 is configured to include a recovery unit (not shown) that collects the polishing liquid 25 used for polishing from the polishing pad 24, and transports the collected polishing liquid 25 to the storage tank 28. The polishing liquid 25 returned to the storage tank 28 is again used by the polishing liquid supply unit 27 to be supplied to the polishing pad 24 through the dropping nozzle 26 for recycling.

Similarly to the above-described polishing apparatus 10, the polishing apparatus 20 can be held by the substrate holding member (carrier) 22 while supplying the polishing liquid 25 from the dropping nozzle 26. The surface to be polished of the glass substrate body 21 contacts the polishing pad 24, and the substrate holding member (carrier) 22 and the polishing platen 23 are relatively rotated and polished.

Examples of the glass of the glass substrate body in the present invention include quartz glass, soda lime glass, aluminosilicate glass, borosilicate glass, aluminum borosilicate glass, alkali-free glass, and crystallized glass.

In particular, for a glass substrate containing an alkali-free glass used in an FPD such as a liquid crystal display (LCD), a strength improvement effect superior to that of the prior art can be obtained.

In the present invention, the alkali-free glass refers to a citrate-based glass in which the content of the alkali metal oxide is less than 2% by mass based on the oxide. More preferably, it is a borosilicate glass or an aluminoborosilicate glass having an alkali metal oxide content of less than 0.5% by mass based on the oxide.

The thickness of the glass substrate is not particularly limited, but is preferably 0.1 to 5 mm. The reinforcement using the polishing in the present invention can obtain a strength improvement effect superior to that of the prior art for a relatively thin glass substrate. As a relatively thin glass substrate, a glass substrate having a thickness of 0.1 to 1.1 mm can be cited.

Furthermore, in the present invention, it is preferable that the difference between the thickness of the glass substrate before polishing and the thickness of the glass substrate obtained after polishing is extremely small, and the thickness of the glass substrate body is preferably 0.1~. 5 mm.

According to the present invention, by using a polishing liquid having a water content of a dispersion medium or less as a specific value or less as a polishing liquid for polishing a glass substrate body, minute irregularities or scratches on the surface of the glass substrate body can be removed with high precision.

Further, by using such a polishing liquid, it is possible to suppress penetration of moisture into the glass during polishing, and it is possible to reduce the amount of moisture in the glass substrate obtained after polishing. Therefore, the strength of the polished glass substrate can be improved with high precision.

[Examples]

Hereinafter, the embodiments of the present invention will be specifically described, but the present invention is not limited to the examples. In the following examples, "%" means % by mass unless otherwise specified.

(1) Preparation of polishing liquid (1-1) Colloidal cerium oxide dispersion <Organic cerium oxide>

Organic cerium oxide dispersion a: EG-ST-ZL manufactured by Nissan Chemical Industry Co., Ltd.

(colloidal cerium oxide (average particle size: 100 nm) 20% by mass, ethylene glycol and water 80% by mass, and water 2% by mass or less)

Organic cerium oxide dispersion b: IPA-ST-ZL manufactured by Nissan Chemical Industry Co., Ltd.

(colloidal cerium oxide (average particle diameter: 120 nm) 20% by mass, isopropyl alcohol and water 80% by mass, and water 1% by mass or less)

Organic ceria dispersion c: MEK-ST-ZL manufactured by Nissan Chemical Industry Co., Ltd.

(colloidal cerium oxide (average particle diameter: 130 nm) 20% by mass, methyl ethyl ketone and water 80% by mass, and water 0.5% by mass or less)

<Water-dispersed colloidal cerium oxide>

Water-dispersed colloidal cerium oxide dispersion a: COMPOL 80 manufactured by Fujimi Incorporated

(colloidal cerium oxide (average particle size 110 nm) 40% by mass, water 60% by mass)

Water-dispersed colloidal cerium oxide dispersion b: ST-ZL manufactured by Nissan Chemical Industry Co., Ltd.

(colloidal cerium oxide (average particle size: 140 nm) 40% by mass, water 60% by mass)

<organic solvent>

Ethanol: Manufactured from Wako Pure Chemicals (reagent grade, moisture 0.2% by mass or less)

Ethylene glycol: manufactured by Wako Pure Chemical (special grade reagent, moisture 0.2% by mass or less)

Methanol: manufactured by Wako Pure Chemicals (special grade reagent, water content 0.1% by mass or less)

n-Propanol: manufactured by Wako Pure Chemicals (reagent grade, moisture 0.2% by mass or less)

N-butanol: Wako Pure Chemical Manufacturing (and light level, moisture 0.3% by mass or less)

Isopropyl alcohol: manufactured by Wako Pure Chemical (special grade reagent, water content 0.1% by mass or less)

Hexane: Wako Pure Chemical Manufacturing (reagent grade, moisture 0.05% by mass or less)

Ethyl acetate: manufactured by Wako Pure Chemical Industries (reagent grade, moisture 0.1% by mass or less)

Toluene: Manufactured from Wako Pure Chemicals (reagent grade, moisture 0.03 mass% or less)

Methyl ethyl ketone: manufactured by Wako Pure Chemical (special grade reagent, water content 0.1% by mass or less)

In addition, the average particle diameter of the abrasive grains in the polishing liquid was measured by a dynamic light scattering method using a particle size analyzer "Microtrac UPA-ST150" (product name, manufactured by NIKKISO Co., Ltd.). The measurement sample is measured by using a pure water or an organic solvent and diluting it to an appropriate concentration range of the device defined by the appropriate scattering and reflected light intensity at the time of measurement.

(1-2)

The studies of Examples 1 to 21 and Comparative Examples 1 to 3 were prepared in the following manner. Grinding liquid.

[Experiment A]

The polishing liquids of Example 1 and Comparative Example 1 were prepared in the following manner.

Specifically, in each of the colloidal cerium oxide dispersions shown in Table 1, the organic solvent or water as a liquid medium was mixed so as to have a ratio shown in Table 1, and then sufficiently stirred to obtain Example 1 And the polishing liquid of Comparative Example 1.

The mixing ratio of the colloidal cerium oxide dispersion liquid, the liquid medium (organic solvent), and water in each of the polishing liquids of Example 1 and Comparative Example 1 was set to a mass ratio when the total mass of each polishing liquid was 100% by mass ( The mass %) is shown in Table 1. As water, pure water is used.

[Experiment B]

The polishing liquids of Examples 2 to 9 and Comparative Examples 2 to 3 were prepared in the following manner.

Specifically, in each of the colloidal cerium oxide dispersions shown in Table 1, the organic solvent or water as a liquid medium was mixed so as to have a ratio shown in Table 1, and then sufficiently stirred to obtain Example 2 ~9 and the polishing solutions of Comparative Examples 2 to 3.

When the ratio of the colloidal cerium oxide dispersion liquid, the liquid medium (organic solvent), and water in each of the polishing liquids of Examples 2 to 9 and Comparative Examples 2 to 3 was set so that the total mass of each polishing liquid was 100% by mass The mass ratio (% by mass) is shown in Table 1. As water, pure water is used.

[Experiment C]

The polishing liquids of Examples 10 to 21 were prepared in the following manner.

Specifically, in each of the colloidal cerium oxide dispersions shown in Table 1, the organic solvent as the liquid medium was mixed so as to have a ratio shown in Table 1, and then sufficiently stirred to obtain Examples 10 to 21. The slurry.

The mixing ratio of the colloidal cerium oxide dispersion liquid and the liquid medium (organic solvent) in each of the polishing liquids of Examples 10 to 21 is a mass ratio (% by mass) when the total mass of each polishing liquid is 100% by mass. Shown in Table 1. As water, pure water is used.

In Table 1, the polishing liquid compositions of Examples 1 to 21 and Comparative Examples 1 to 3, the abrasive grains, the dispersion medium (total amount), and water (including the organic solvent and the water-dispersed colloid-derived dioxide) of each polishing liquid. The content ratio (concentration: mass%) of the entire liquid to the polishing liquid, and the content ratio (% by mass) of water to the entire dispersion medium are shown together with the ratio of the above-mentioned respective colloidal cerium oxides. Table 1.

Further, the polishing liquid composition (abrasive grains, dispersion medium, and water) is described in terms of the mass % of the entire polishing liquid obtained by the preparation. In addition, the ratio of the water content to the entire polishing liquid (concentration: mass%) and the ratio of water in the dispersion medium are calculated based on the amount of water contained in the colloidal cerium oxide dispersion liquid and the organic solvent, and the water is calculated in the entire polishing liquid. The value obtained by the ratio of the content of the medium and the ratio of the water to the total value of the dispersion medium as a whole.

(2) Evaluation of the grinding characteristics of the polishing liquid

With respect to the polishing liquids obtained in Examples 1 to 21 and Comparative Examples 1 to 3, the polishing performance was evaluated by the following method.

(2-1) Grinding conditions

The polishing was carried out under the conditions shown below using the following apparatus.

Grinding machine: table lapping machine NF-300 (manufactured by Nano Factor)

Grinding pressure: shown in Table 2.

Platen speed: shown in Table 2.

Head (substrate holding portion) rotation speed: shown in Table 2.

Slurry supply speed: 40 ml / min

Grinding pad: Suede Pad H7000 (manufactured by FUJIBO EHIME)

Grinding time: shown in Table 2.

(2-2) the object to be polished

As the object to be polished, the following pretreated glass substrate was applied to an alkali-free glass AN100 (trade name, manufactured by Asahi Glass Co., Ltd.) for FPD having a thickness of 0.5 mm.

(a) [Experiment A]

A glass substrate obtained by polishing the surface of the AN100 substrate for 3 minutes using a ruthenium abrasive (铈 concentration: 10% by mass, ruthenium particle diameter: 0.5 μm) was used.

(b) [Experiment B]

A mixture of a water-dispersed colloidal ceria dispersion a and pure water in a ratio of 1:1 by mass ratio is used for the AN100 substrate. The surface was polished for 30 minutes to obtain a glass substrate.

(c) [Experiment C]

A glass substrate obtained by polishing the surface of the AN100 substrate for 30 minutes by using a mixed liquid obtained by mixing a water-dispersed colloidal cerium oxide dispersion a and pure water at a mass ratio of 1:1 was used.

(2-3) Method for evaluating characteristics of polishing liquid

The strength of the glass substrate obtained after the polishing was evaluated by the method shown below (Ball on Ring measurement method). In other words, each of the glass substrates of Examples 1 to 21 and Comparative Examples 1 to 3 was placed on an annular table (diameter: 30 mm) with the evaluation surface facing downward, and then a steel ball having a diameter of 10 mm was pressed against the glass substrate. On the upper surface, a load was applied under the condition of a head speed of 1 mm/sec, and the load when the substrate was broken was used as the strength of the glass substrate.

In the measurement of the strength of the glass substrate, Autograph AG-1 (trade name, manufactured by Shimadzu Corporation) was used. In the evaluation of the strength of the above-mentioned glass substrate, three glass substrates of the respective examples and comparative examples were prepared, and the highest value of the measurement value obtained by each was used as the strength of the glass substrate. In addition, the glass substrate strength before the polishing treatment is a value obtained by evaluating the glass substrate processed and treated under the same conditions as those in the respective experiments A to C using the above-described strength measurement method.

The evaluation results are shown in Table 2. Further, in Examples 2 to 9 and Comparative Examples 2 to 3 (Experiment B), the relationship between the content ratio of water in the dispersion medium of the polishing liquid and the strength of the glass substrate after polishing is shown in Fig. 3 .

As is clear from the results of Table 2, in Comparative Example 1 in which the polishing liquid containing 100% of the total mass of water with respect to the dispersion medium was used, the strength of the glass substrate obtained after the polishing was only 690 N. On the other hand, the glass substrate of Example 1 obtained by polishing the polishing liquid having a content ratio of water to the total mass of the dispersion medium of 1% or less obtained a high strength of 836 N, and the precision was high. Increase the strength of the glass substrate.

In addition, as is clear from the results of Table 2 and FIG. 3, the glass substrates of Examples 2 to 9 obtained by polishing using a polishing liquid having a water content of 85% by mass or less based on the total mass of the dispersion medium were confirmed. In the middle, the strength of the glass substrate body having a strength of 690 N is increased to 763 N or more, and as the water content ratio is lowered, higher strength can be obtained. On the other hand, it was confirmed that the glass substrates of Comparative Examples 2 to 3 obtained by polishing using a polishing liquid containing more than 85% by mass of water based on the total mass of the dispersion medium obtained only a strength of 723 N or less, particularly in a dispersion medium. In Comparative Example 3 in which the water content ratio was 100%, the strength was lower than that of the glass substrate before polishing.

In addition, in Examples 10 to 21 in which the types of the organic solvents to be blended in the polishing liquid were variously changed, the glass substrate obtained after the polishing also obtained a high strength of 747 N or more, and was improved with high precision. The strength of the glass substrate. It can be confirmed that in Examples 10 to 14 in which a polishing liquid containing ethylene glycol in a dispersion medium is used, a higher strength of 810 to 840 N can be obtained.

The present application is based on Japanese Patent Application No. 2011-240117, filed on Jan.

[Industrial availability]

According to the present invention, it is possible to perform high-precision polishing on the glass substrate body, in particular, the alkali-free glass substrate body for FPD, and it is possible to improve the strength of the glass substrate obtained after polishing with higher precision than before.

1‧‧‧grinding platen

2‧‧‧ Platen drive motor

3‧‧‧ polishing pad

4‧‧‧glass substrate body

5‧‧‧Substrate holding member

6‧‧‧Drip nozzle

7‧‧‧Slurry

10‧‧‧ grinding device

20‧‧‧ grinding device

21‧‧‧ glass substrate body

22‧‧‧Substrate holding member

23‧‧‧grinding platen

24‧‧‧ polishing pad

25‧‧‧Slurry

26‧‧‧Drip nozzle

27‧‧‧Slurry supply unit

28‧‧‧Storage tank

C1‧‧‧ Axis

C2‧‧‧ Axis

Fig. 1 is a view showing an example of a polishing apparatus which can be used in the method for producing a glass substrate of the present invention.

Fig. 2 is a view showing an example of a polishing apparatus which can be used in the method for producing a glass substrate of the present invention.

Fig. 3 is a graph showing the relationship between the content ratio of water in the dispersion medium and the strength of the glass substrate obtained after the polishing.

1‧‧‧grinding platen

2‧‧‧ Platen drive motor

3‧‧‧ polishing pad

4‧‧‧glass substrate body

5‧‧‧Substrate holding member

6‧‧‧Drip nozzle

7‧‧‧Slurry

10‧‧‧ grinding device

C1‧‧‧ Axis

C2‧‧‧ Axis

Claims (13)

A method for producing a glass substrate, which is dispersed in a dispersion medium containing a liquid medium other than water containing no water or containing water (in which the content of water in the dispersion medium is 85% by mass or less) The polishing liquid of the abrasive grains is polished on at least one main surface of the glass substrate body. The method for producing a glass substrate according to claim 1, wherein the content of water in the dispersion medium is from 3 to 60% by mass. The method for producing a glass substrate according to claim 1, wherein the content of water in the dispersion medium is less than 3% by mass. The method for producing a glass substrate according to any one of claims 1 to 3, wherein the liquid medium other than the water is an organic solvent. The method for producing a glass substrate according to claim 4, wherein the organic solvent is a monohydric or polyhydric alcohol. The method for producing a glass substrate according to claim 4, wherein the organic solvent is a hydrocarbon, an ether, an ester or a ketone. The method for producing a glass substrate according to any one of claims 1 to 4, wherein the liquid medium other than the water is selected from the group consisting of methanol, ethanol, n-propanol, isopropanol, n-butanol, ethylene glycol, propylene glycol, At least one of a group consisting of n-hexane, octane, ethyl acetate, methyl ethyl ketone, toluene, and diethyl ether. The method for producing a glass substrate according to any one of claims 1 to 7, wherein the abrasive particles are at least one selected from the group consisting of cerium oxide, aluminum oxide, cerium oxide, titanium oxide, zirconium oxide and manganese oxide. A fine particle of a metal oxide. The method for producing a glass substrate according to any one of claims 1 to 8, wherein the abrasive grains are particles having an average particle diameter of 5 to 500 nm. The method for producing a glass substrate according to any one of claims 1 to 9, wherein the content of the abrasive grains contained in the polishing liquid is 0.1 to 40% by mass based on the total mass of the polishing liquid. The method for producing a glass substrate according to any one of claims 1 to 10, wherein the polishing liquid is supplied to the polishing pad to bring the polished surface of the glass substrate main body into contact with the polishing pad, and the relative movement between the two The surface to be polished is ground. The method for producing a glass substrate according to any one of claims 1 to 11, wherein the glass substrate is a glass substrate comprising an alkali-free glass. The method for producing a glass substrate according to any one of claims 1 to 12, wherein the glass substrate has a thickness of 0.1 to 5 mm.