Polishing agent, glass plate, method for polishing glass, and method for producing glass

Abstract

The purpose of the present invention is to improve the amount of polishing per unit time while achieving a high level of smoothness. The polishing agent (1) contains amorphous carbon (10), water (12), and an acid (14) other than a polymer, the content of the amorphous carbon (10) is 0.005-50 mass% with respect to the entire polishing agent (1), and the number of acid groups contained per 1 kg of the polishing agent is 0.45 mmol / kg or more.

Description

Technical Field

[0001] The present invention relates to an abrasive, a glass plate, a method for grinding glass, and a method for manufacturing glass. Background Art

[0002] As an abrasive for the surface of a glass plate, cerium oxide, colloidal silica, etc. are generally used. Further, in recent years, the requirement for the smoothness of the glass plate has become higher, and particularly in the case of being used as an optical material such as a light guide plate, a higher level of smoothness is required. For example, Patent Document 1 describes using amorphous carbon as an abrasive in order to achieve a high level of smoothness.

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: WO 2021 / 053732 Summary of the Invention

[0006] Here, in the case of using carbon as an abrasive, it is required to achieve a high level of smoothness and increase the grinding amount per unit time.

[0007] An object of the present invention is to provide an abrasive, a glass plate, a method for grinding glass, and a method for manufacturing glass that can achieve a high level of smoothness and increase the grinding amount per unit time.

[0008] The abrasive of the present disclosure contains amorphous carbon, water, and an acid other than a polymer-based one. The content of the amorphous carbon is 0.005% by mass to 50% by mass with respect to the whole of the abrasive, and the number of acid groups contained in 1 kg of the abrasive is 0.45 mmol / kg or more.

[0009] The glass plate of the present disclosure is a glass plate ground using the above abrasive.

[0010] The method for grinding glass of the present disclosure is to grind glass using the above abrasive.

[0011] The method for manufacturing glass of the present disclosure is to manufacture glass using the above method for grinding glass.

[0012] According to the present invention, a high level of smoothness can be achieved and the grinding amount per unit time can be increased. Brief Description of the Drawings

[0013] Figure 1 is a schematic view of the abrasive of the present embodiment.

[0014] Figure 2 is a schematic view for explaining the method for manufacturing glass of the present embodiment. Detailed Description

[0015] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that the present invention is not limited by this embodiment, and in the case of having a plurality of embodiments, it also includes embodiments constituted by combining each embodiment. In addition, for numerical values, ranges including rounding are included.

[0016] (Abrasive)

[0017] Figure 1 is a schematic diagram of the abrasive of this embodiment. The abrasive 1 of this embodiment is an abrasive for grinding glass. As Figure 1 shown, the abrasive 1 includes amorphous carbon 10, water 12, and acid 14.

[0018] (Amorphous carbon)

[0019] The abrasive 1 includes amorphous carbon 10 as abrasive grains. Amorphous carbon 10 is an amorphous carbon that does not have a crystal structure, and is a carbon that does not have a planar crystal structure such as a graphite structure or a crystal structure such as a diamond. Amorphous carbon is sometimes also called amorphous carbon. Amorphous carbon 10 can be manufactured, for example, by the oil furnace method. In the oil furnace method, for example, after spraying the raw material oil in a high-temperature atmosphere of 1300 degrees or more and thermally decomposing it, rapid cooling is performed to manufacture amorphous carbon. However, the manufacturing method of amorphous carbon 10 is not limited to this and can be arbitrary.

[0020] Amorphous carbon can be identified by X-ray diffraction method. For example, when the peak waveform in the X-ray diffraction analysis result of the carbon as the analysis object is different from the peak waveforms in the known graphite structure and the known diamond structure, it can be determined as amorphous carbon. It should be noted that as the peak waveform in the graphite structure, the data of ICSD No.53780 and No.53781 can be used, and as the peak waveform in the diamond structure, the data of ICSD No.53779 can be used.

[0021] In addition, in this application, since an amorphous does not have a crystal structure, it is sometimes called a primary structure, an extended graphite having a two-dimensional crystal structure is sometimes called a secondary structure, and an extended crystal having a three-dimensional crystal structure is sometimes called a tertiary structure.

[0022] The amorphous carbon 10 is preferably hydrophilic. For example, by subjecting the hydrophobic amorphous carbon 10 contained in the abrasive 1 to a hydrophilization treatment, the amorphous carbon 10 can be made hydrophilic. Generally, amorphous carbon exhibits hydrophobicity and has poor dispersibility in water. Hydrophilic amorphous carbon has good dispersibility in pure water. Therefore, compared with the hydrophobic amorphous carbon whose surface has not been subjected to a hydrophilization treatment, it can be appropriately used even at a lower concentration, and thus is preferred. The method of hydrophilization treatment is not limited. For example, hydrophilic groups can be formed on the surface of the amorphous carbon by known methods such as surface modification using plasma treatment, UV treatment, surfactants, etc. That is, amorphous carbon having hydrophilic groups on the surface and relatively high affinity with water can be said to be hydrophilic amorphous carbon. As hydrophilic groups, hydroxyl groups are generally used, but in addition, carboxyl groups, amino groups, ethylene oxide, etc. can also be cited.

[0023] The shape and particle size of the amorphous carbon 10 can be arbitrary. For example, the average primary particle size of the amorphous carbon 10 is preferably 20 nm to 500 nm, more preferably 20 nm to 150 nm. It should be noted that the primary particle size refers to the particle size of one particle, and the average primary particle size refers to the average value of the primary particle sizes. By setting the average primary particle size of the amorphous carbon 10 to 20 nm or more, the surface roughness of the ground glass can be appropriately reduced, and by setting it to 500 nm or less, the formation of damage on the surface of the ground glass can be appropriately suppressed.

[0024] It should be noted that the method for measuring the average primary particle size of the amorphous carbon 10 can be arbitrary. For example, based on the specific surface area (m 2 / g) measured by the BET method and the density of carbon (for example, 1.5 g·cm 3 ), assuming that the particles are spherical and there are no pores in the abrasive grains, the BET diameter is obtained, and the average primary particle size is calculated based on this BET diameter. In addition, methods such as directly observing the particles using a scanning electron microscope, measuring the particle sizes of hundreds of particles using image analysis, and measuring the average primary particle size based on their average values can be cited. A transmission electron microscope can be used instead of a scanning electron microscope.

[0025] The average dispersion diameter of the amorphous carbon 10 is preferably 20 nm to 500 nm, more preferably 50 nm to 300 nm, and further preferably 100 nm to 200 nm. By the average dispersion diameter being in this range, the glass can be appropriately ground.

[0026] The average dispersion diameter of the amorphous carbon 10 can be measured using a particle size distribution meter using the dynamic light scattering method.

[0027] The zeta potential of the amorphous carbon 10 in the polishing agent 1 is preferably -80 mV to -5 mV, more preferably -50 mV to -5 mV, further preferably -40 mV to -5 mV, and most preferably -30 mV to -5 mV. When the zeta potential is within this range, the contact barrier between the amorphous carbon and the glass substrate becomes small, and the glass can be polished while increasing the polishing amount per unit time.

[0028] Zeta potential can be measured by electrophoresis or using an electroacoustic zeta potential meter.

[0029] As amorphous carbon 10, compared with the structure formed by other inorganic materials or organic materials, it is preferred that the composition unevenness from the center to the surface of the particle is smaller, and it is preferred to use amorphous carbon that does not contain elements other than carbon as much as possible. In other words, amorphous carbon 10 is not a core-shell structure consisting of a core composed of an inorganic material or organic material other than carbon and a shell composed of amorphous carbon covering the core, or a core-shell structure consisting of a core composed of amorphous carbon and a shell composed of an inorganic material or organic material other than carbon covering the core, but is preferably a structure of amorphous carbon simple substance. For example, even if some particles are used as cores and the core is covered with carbon, the effect obtained will not change. Not only that, there is also a particle disintegration from the interface of the core and the carbon as the shell, and the material forming the core acts as an abrasive, thereby promoting the possibility of damage to the glass surface. Or even if carbon is used as a core and covered with a certain material such a core-shell structure, since carbon cannot directly contact the substrate surface, it is impossible to suppress damage and achieve a high level of smoothness.

[0030] The ratio of the content of the amorphous carbon 10 in the abrasive 1 (amount of amorphous carbon / abrasive amount) relative to the entire abrasive 1 is 0.005% to 50% by mass, preferably 0.001% to 20% by mass, more preferably 0.01% to 15% by mass, further preferably 0.05% to 10% by mass, particularly preferably 0.1% to 5% by mass, and further preferably 0.5% to 3% by mass. When the content of the amorphous carbon 10 is within this range, the glass can be polished while increasing the polishing amount per unit time, and further, the glass can be appropriately polished while suppressing damage to the surface of the glass.

[0031] (water)

[0032] The water 12 contained in the polishing agent 1 can be said to be a medium for dissolving the acid 14. That is, the polishing agent 1 can be said to be an aqueous solution containing the amorphous carbon 10 as abrasive grains and the acid 14. The water 12 is preferably pure water.

[0033] (acid)

[0034] The acid 14 contained in the abrasive 1 is an acidic substance. The acid 14 exists in the abrasive 1 in a state dissolved in water 12, and further, in a state where at least a part thereof is ionized.

[0035] The acid 14 can be any acidic substance. For example, the acid dissociation constant Ka at 25°C is preferably -4 to 6, more preferably -2 to 5, and still more preferably 0 to 4. The acid 14 is a strong acid with an acid dissociation constant Ka in this range, whereby the glass can be polished while increasing the polishing amount per unit time. The acid dissociation constant Ka can be measured by filtering the amorphous carbon 10 from the abrasive 1 in advance using centrifugation, membrane filters, etc., neutralizing and titrating the obtained filtrate with KOH, and plotting the KOH addition amount and the pH change amount.

[0036] The acid 14 is preferably an organic acid, more preferably a chelating agent. When the acid 14 is an organic acid, the molecular weight of the acid 14 is preferably from 30 g / mol to 1000 g / mol, more preferably from 60 g / mol to 800 g / mol, still more preferably from 80 g / mol to 700 g / mol, particularly preferably from 100 g / mol to 600 g / mol, and even more particularly preferably from 150 g / mol to 500 g / mol. By using an organic acid having a molecular weight in this range, it is possible to grind the glass while increasing the grinding amount per unit time. In addition, by using an acid having a not-too-large molecular weight in this way, it is possible to suppress the hindrance to the grinding rate caused by the firm adsorption of the organic acid to the glass substrate, and in addition, it is possible to suppress the induction of defects due to the residue of the organic acid as an organic residue on the glass substrate. The structure of the acid 14 is arbitrary, but compared with an acid contained in a monomer unit in a polymer, it is preferably present as a monomer. This is because: when present as a polymer, the effect of increasing the grinding amount per unit time is weakened, and when present as a monomer, the effect of increasing the grinding amount per unit time can be maximized. In other words, the acid 14 is an acid other than a polymer-based acid, that is, it is not a polymer-based acid. A polymer-based acid refers to an acid formed by dissolving an acidic water-soluble polymer in water, and examples thereof include polycarboxylic acid, polyphosphonocarboxylic acid, polyacrylic acid, and polysulfonic acid. A polymer refers to a high molecule formed by connecting a plurality of monomers that form a unit structure. Although there is no clear definition, a substance with a degree of polymerization of several hundred or more is called a polymer. In terms of molecular weight, sometimes a substance with a molecular weight of 10,000 or more is called a polymer, but sometimes a substance with a repeating structure with a molecular weight of about several thousand is also included in the polymer. In the present embodiment, a substance with a repeating structure with a molecular weight of 10,000 or more is called a polymer, and preferably a substance with a molecular weight of 1,000 or more is called a polymer. It should be noted that a substance formed by connecting two monomers is called a dimer, a substance formed by connecting three is called a trimer, and a substance formed by connecting four is called a tetramer, and these are mostly distinguished from polymers. In addition, sometimes a polymer with a relatively low degree of polymerization of up to about a dozen molecules is also called an oligomer. In the present embodiment, a polymer-based acid refers to an acid of an organic substance with a degree of polymerization of 100 or more that does not include monomers, dimers, trimers, tetramers, and oligomers, and preferably refers to an acid of an organic substance with a degree of polymerization of 20 or more. However, as the polymer-based acid in the present embodiment, oligomers may be included, and more preferably refers to an acid of an organic substance with a degree of polymerization of 5 or more.

[0037] As the acid 14, at least one of hydrochloric acid, sulfuric acid, hydroxylethylidene diphosphonic acid (HEDP), phytic acid, orthophosphoric acid, pyrophosphoric acid, nitrilotrimethylphosphonic acid, ethylenediaminetetraacetic acid, and diethylenetriaminepentaacetic acid is preferably used. As the acid 14, HEDP is more preferably used.

[0038] The content of acid 14 in abrasive 1 can be arbitrary. For example, with respect to the content of amorphous carbon 10 in abrasive 1, the ratio of the content of acid 14 in abrasive 1 (acid amount / amorphous carbon amount) is preferably 0.02% by mass to 100% by mass, more preferably 0.04% by mass to 50% by mass, still more preferably 0.1% by mass to 40% by mass, particularly preferably 0.2% by mass to 30% by mass, and even more particularly preferably 0.5% by mass to 20% by mass. By the content of acid 14 being within this range, the grinding amount per unit time can be increased and the deterioration of operability caused by excessive acid 14 can be suppressed.

[0039] It should be noted that the ratio of the content of acid 14 to the content of amorphous carbon 10 can be measured, for example, in the following manner. By filtering using centrifugation, membrane filters, etc., amorphous carbon 10 is pre-separated from abrasive 1. After completely removing the moisture from the separated solid component (amorphous carbon 10), the weight of this solid component is measured, whereby the abrasive grain concentration (the content of amorphous carbon 10 in abrasive 1) contained in the slurry can be measured. The abrasive grain concentration can also be simply measured using a solid component meter. The acid concentration (the content of acid 14 in abrasive 1) can be measured using the calibration curve method. Specifically, a plurality of standard samples with known acid concentrations are prepared, and the signal intensities of the standard samples are measured by the analysis methods of the ionic species of the acid groups described later (liquid chromatography such as ion chromatography, colorimetry, precipitation titration, FT-IR, etc.), and a calibration curve showing the corresponding relationship between the signal intensity and the acid concentration is generated. Then, the signal intensity of abrasive 1 to be measured can be measured using the same analysis method as the standard sample, and the acid concentration can be measured based on the measured signal intensity and the calibration curve. When amorphous carbon 10 becomes an obstructive factor in the measurement of the acid concentration, it can be carried out by pre-separating amorphous carbon through filtering using centrifugation, membrane filters, etc. In addition, when cations have a negative impact on the measurement, treatment using a cation exchange resin, etc. can be carried out in advance for pre-separation.

[0040] The ratio of the content of acid 14 to the content of amorphous carbon 10 can be measured based on these values (abrasive grain concentration and acid concentration).

[0041] (acid group)

[0042] As described above, since at least a part of acid 14 ionizes in abrasive 1, acid groups are contained in abrasive 1. It can also be said that the acid groups in abrasive 1 are included in the ions in which protons are separated from the molecules of acid 14.

[0043] For abrasive 1, the amount of acid groups contained in 1 kg of the abrasive (the number of moles of acid groups per 1 kg of the abrasive) is 0.45 mmol / kg or more, preferably 0.45 mmol / kg to 400 mmol / kg, more preferably 0.095 mmol / kg to 300 mmol / kg, still more preferably 1.8 mmol / kg to 200 mmol / kg, particularly preferably 4 mmol / kg to 100 mmol / kg, and even more particularly preferably 9 mmol / kg to 50 mmol / kg. In addition, by having the amount of acid groups contained in 1 kg of the abrasive be 0.45 mmol / kg or more, the grinding amount per unit time can be increased, and by being 400 mmol / kg or less, deterioration of workability caused by an excessive amount of acid groups can be suppressed.

[0044] The amount of acid groups contained in 1 kg of the abrasive can be measured as follows. That is, amorphous carbon 10 can be separated in advance from abrasive 1 by filtration using centrifugation, membrane filters, etc., and the filtrate obtained can be analyzed by the analysis method of the type of acid group described later to determine the type of acid, and the structure of the acid skeleton can be determined based on 1H NMR and 13C NMR for measurement. If acid 14 is a polymer having a repeating structure, it can be measured by colloid titration.

[0045] It should be noted that the amount of acid groups contained in 1 kg of the abrasive can be adjusted by any method. For example, it can be adjusted by setting the ratio of the content of acid 14 and water 12 according to the type of acid 14.

[0046] In addition, when multiple types of acid 14 are included and the acid groups contained in abrasive 1 also have multiple types, the above-mentioned amount of acid groups can refer to the total value of the amounts of various acid groups contained in 1 kg of the abrasive.

[0047] Abrasive 1 preferably contains at least one of a phosphonic acid group, a carboxylic acid group, and a sulfonic acid group as the acid group. Abrasive 1 more preferably contains a phosphonic acid group as the acid group. When the acid group is a phosphonic acid group, it is preferred to contain 2 to 4 acid groups in one molecule (ion) of acid 14.

[0048] The type of the acid group can be determined by various analysis methods according to the ionic species of the acid group, and can be determined by liquid chromatography such as ion chromatography, colorimetric determination, precipitation titration, and FT-IR. In addition, the approximate acid group can be inferred by obtaining the acid dissociation constant pKa. For the case of having multiple acid dissociation constants pKa, the acid group can be determined by comparison with the literature values. When amorphous carbon 10 becomes an obstacle, it can be carried out by pre-separating amorphous carbon 10 from the abrasive 1 by filtration using centrifugation, membrane filters, etc. In addition, when cations have a negative impact on the determination, treatment using a cation exchange resin, etc. can be carried out in advance for pre-separation.

[0049] (Other components)

[0050] In addition to amorphous carbon 10, water 12, and acid 14, the abrasive 1 may contain other components. As the other components, known additives such as a dispersant can be used, and the additive can be contained at most 10% by mass based on the whole of the abrasive 1. As the dispersant, polymers having a carboxyl group, a sulfone group, a hydroxyl group, etc. at the terminal, nonionic surfactants, anionic surfactants, cationic surfactants, etc. can be cited. By adding a dispersant to the abrasive 1, amorphous carbon can be appropriately dispersed in water, and the grinding surface of the glass G can be made uniform. For example, the content of the dispersant in the abrasive 1 is preferably 0.001% by mass to 10% by mass based on the whole of the abrasive 1. When the content of the dispersant is 0.001% or more, amorphous carbon can be appropriately dispersed in water, and when the content of the dispersant is 10% or less, excessive consumption of the dispersant can be suppressed.

[0051] (Effect)

[0052] Here, when grinding glass using an abrasive containing carbon, sometimes the grinding amount of the glass per unit time becomes less. The grinding amount of the glass per unit time refers to the change amount of the thickness of the glass when the glass is ground for a unit time using the abrasive, and hereinafter, it is appropriately described as the grinding rate. If the grinding rate becomes low, the time required for the grinding process becomes long, or carbon accumulates on the grinding surface of the glass, causing white fog (a phenomenon of white turbidity on the glass surface).

[0053] In contrast, in the present embodiment, after setting the content of the amorphous carbon 10 to 0.005 wt% to 50 wt%, the abrasive 1 contains the acid 14, and the number of acid groups contained in each 1 kg of the abrasive is set to 0.45 mmol / kg or more. Thereby, the polishing of glass can be promoted, the decrease in the polishing rate can be suppressed, and the elongation of the time required for the polishing process or the white fog can be suppressed. It is known that amorphous carbon does not have hydroxyl groups on its surface, or has fewer hydroxyl groups compared to particles of inorganic materials generally used as abrasive grains. When polishing glass with an inorganic material, after the hydroxyl groups present on the surface of the inorganic material form a bond with the glass, a part of the glass is removed by physical force due to the pressure or rotation of the polishing machine. Therefore, amorphous carbon with fewer or almost no surface hydroxyl groups is inherently not conducive to polishing. As a result, it is considered that a slurry containing amorphous carbon without additives does not exhibit a polishing rate. However, it is considered that by adding the acid 14 as in the abrasive 1 of the present embodiment, when an inorganic material is used as the abrasive grains, the surface hydroxyl groups of the inorganic material itself form a bond with the glass, and the acid plays a part of the role of the bond, thereby exhibiting a polishing rate. The substrate to be polished using the abrasive 1 is not particularly limited, but a glass substrate is most suitable. As substrates that require precision polishing to improve surface smoothness, there are aluminum substrates for hard disks, silicon substrates for semiconductors, various thin films formed on silicon, silicon carbide substrates for power devices, gallium nitride substrates, etc. However, as described above, it is considered that the present embodiment exhibits an effect through the interaction generated between the substrate and the abrasive grains. By using a glass substrate as the polishing object, the interaction with the abrasive 1 can be appropriately exerted, and polishing can be appropriately performed. In addition, the abrasive 1 is also effective for glass having a high refractive index used for optical materials such as light guide plates in a glass substrate. In particular, for a glass substrate having a refractive index of 1.8 or more, the mechanical properties of the glass itself, especially the hardness or Young's modulus, become high, and thus there is a problem that the amount of glass polished per unit time becomes low. It is known that if the slurry in Patent Document 1 is used, even for glass having a refractive index of less than 1.8, the amount of glass polished per unit time is very low. In contrast, according to the abrasive 1 of the present embodiment, a high level of smoothness can be achieved for glass having a refractive index of less than 1.8 and the polishing amount per unit time can be increased, and for glass having a refractive index of 1.8 or more, this effect can be further significant.

[0054] (Glass)

[0055] The glass G polished using the abrasive 1 can be arbitrary, but preferably has the following composition. That is, for example, in the glass G polished using the abrasive 1, in terms of mass % based on oxides, it preferably contains at least one selected from La2O3, TiO2, and Bi2O3 in an amount of 1 mass % to 80 mass % as a glass-forming component. The abrasive 1 is particularly effective for polishing the glass G having such a composition. Additionally, the glass G is more preferably within any of the following compositional ranges of glass GA, GB, GC, and GD.

[0056] (Glass GA)

[0057] For example, in the glass GA, in terms of mass % based on oxides, when the total of the basic composition of the glass GA is set to 100 mass %, it contains 5 mass % to 70 mass % of La2O3 and 5 mass % to 70 mass % of TiO2. Hereinafter, unless otherwise specified, the content of the oxide is based on oxides when the total of the basic composition is set to 100%.

[0058] In addition, in terms of mole % based on oxides, the glass GA preferably contains: 5% to 20% of SiO2, 10% to 30% of B2O3, 3% to 10% of ZrO2, 10% to 40% of TiO2, 1% to 7% of Nb2O5, 10% to 30% of La2O3, 0% to 10% of Gd2O3, and 0% to 10% of Y2O3.

[0059] (SiO2)

[0060] In addition, in terms of mole % based on oxides in the glass GA, the content of SiO2 is preferably 5.0% or more, more preferably 7.0% or more, and further preferably 9.0% or more. In addition, in terms of mole % based on oxides in the glass GA, the content of SiO2 is preferably 20.0% or less, more preferably 18.0% or less, further preferably 16.0% or less, further preferably 14.0% or less, and further preferably 12.0% or less.

[0061] It should be noted that the upper limit value and the lower limit value of the content here can be appropriately combined, and the same applies hereinafter.

[0062] (B2O3)

[0063] In addition, in glass GA, when expressed in terms of mol% based on oxides, the content of B2O3 is preferably 10.0% or more, more preferably 14.0% or more, further preferably 17.0% or more, and still further preferably 20.0% or more. In addition, when expressed in terms of mol% based on oxides, the content of B2O3 in glass GA is preferably 30.0% or less, more preferably 29.0% or less, further preferably 27.0% or less, still further preferably 25.0% or less, and even further preferably 24.0% or less.

[0064] (ZrO2)

[0065] In addition, in glass GA, when expressed in terms of mol% based on oxides, the content of ZrO2 is preferably 3.0% or more, more preferably 4.0% or more, further preferably 5.0% or more, and still further preferably 6.0% or more. In addition, when expressed in terms of mol% based on oxides, the content of ZrO2 in glass GA is preferably 10.0% or less, more preferably 9.0% or less, further preferably 8.0% or less, and still further preferably 7.0% or less.

[0066] (TiO2)

[0067] In addition, in glass GA, when expressed in terms of mol% based on oxides, the content of TiO2 is preferably 10.0% or more, more preferably 15.0% or more, further preferably 20.0% or more, still further preferably 25.0% or more, and even further preferably 30.0% or more. In addition, when expressed in terms of mol% based on oxides, the content of TiO2 in glass GA is preferably 40.0% or less, more preferably 38.0% or less, further preferably 36.0% or less, still further preferably 34.0% or less, and even further preferably 32.0% or less.

[0068] (Nb2O5)

[0069] In addition, in glass GA, when expressed in terms of mol% based on oxides, the content of Nb2O5 is preferably 1.0% or more, more preferably 2.0% or more, further preferably 3.0% or more. In addition, when expressed in terms of mol% based on oxides, the content of Nb2O5 in glass GA is preferably 7.0% or less, more preferably 6.0% or less, further preferably 5.0% or less, and still further preferably 4.0% or less.

[0070] (La2O3)

[0071] In addition, in glass GA, in terms of mol% based on oxides, the content of La2O3 is preferably 10.0% or more, more preferably 12.0% or more, further preferably 14.0% or more, and further preferably 18.0% or more. In addition, in glass GA, in terms of mol% based on oxides, the content of La2O3 is preferably 30.0% or less, more preferably 28.0% or less, further preferably 26.0% or less, further preferably 24.0% or less, and further preferably 22.0% or less.

[0072] (Gd2O3)

[0073] In addition, in glass GA, in terms of mol% based on oxides, the content of Gd2O3 is preferably 0.0% or more, more preferably 1.0% or more, further preferably 2.0% or more, further preferably 3.0% or more, and further preferably 3.5% or more. In addition, in glass GA, in terms of mol% based on oxides, the content of Gd2O3 is preferably 10.0% or less, more preferably 9.0% or less, further preferably 8.0% or less, further preferably 7.0% or less, further preferably 6.0% or less, further preferably 5.0% or less, and further preferably 4.0% or less.

[0074] (Y2O3)

[0075] In addition, in glass GA, in terms of mol% based on oxides, the content of Y2O3 is preferably 0.0% or more, more preferably 1.0% or more, further preferably 2.0% or more, further preferably 3.0% or more. In addition, in glass GA, in terms of mol% based on oxides, the content of Y2O3 is preferably 10.0% or less, more preferably 9.0% or less, further preferably 8.0% or less, further preferably 7.0% or less, further preferably 6.0% or less, and further preferably 5.0% or less.

[0076] (Glass GB)

[0077] For example, in glass GB, in terms of mass% based on oxides, when the total of the basic composition of glass GB is set to 100%, it contains 10% to 80% by mass of Bi2O3 and 5% to 60% by mass of TeO2.

[0078] In terms of mol% based on oxides, glass GB preferably contains: 1% to 30% of P2O5, 1% to 15% of Nb2O5, and 15% to 40% of Bi2O3.

[0079] (P2O5)

[0080] In the glass GB, the content of P2O5 is preferably 1.0% or more, more preferably 3.0% or more, further preferably 5.0% or more, further preferably 7.0% or more, and further preferably 9.0% or more, in terms of mol% based on oxides. In the glass GB, the content of P2O5 is preferably 30.0% or less, more preferably 25.0% or less, further preferably 20.0% or less, further preferably 15.0% or less, and further preferably 10.0% or less, in terms of mol% based on oxides.

[0081] (Nb2O5)

[0082] In the glass GB, the content of Nb2O5 is preferably 1.0% or more, more preferably 2.0% or more, further preferably 3.0% or more, further preferably 4.0% or more, further preferably 5.0% or more, further preferably 6.0% or more, and further preferably 6.5% or more, in terms of mol% based on oxides. In the glass GB, the content of Nb2O5 is preferably 15.0% or less, more preferably 13.0% or less, further preferably 11.0% or less, further preferably 9.0% or less, and further preferably 7.0% or less, in terms of mol% based on oxides.

[0083] (Bi2O3)

[0084] In the glass GB, the content of Bi2O3 is preferably 15.0% or more, more preferably 20.0% or more, and further preferably 30.0% or more, in terms of mol% based on oxides. In the glass GB, the content of Bi2O3 is preferably 40.0% or less, more preferably 35.0% or less, and further preferably 33.0% or less, in terms of mol% based on oxides.

[0085] (Glass GC)

[0086] For example, in terms of mass% based on oxides, when the total of the basic composition of the glass GC is set to 100%, the glass GC contains 40 mass% to 95 mass% of at least one selected from SiO2, Al2O3, and B2O3, and 0.1 mass% to 5 mass% of at least one selected from TiO2 and ZrO2.

[0087] In terms of mol% based on oxides, the glass GC preferably contains: 55% to 75% of SiO2, 5% to 25% of Al2O3, 0% to 15% of B2O3, 0% to 15% of MgO, 0% to 15% of CaO, 0% to 10% of SrO, 0% to 10% of BaO, 0% to 10% of Na2O, 0% to 10% of K2O, 0% to 15% of Li2O, 0% to 5% of TiO2, and 0% to 5% of ZrO2.

[0088] (Glass GD)

[0089] For example, when the total of the basic composition of glass GD is set to 100% in terms of mass% on an oxide basis, it contains 40 mass% to 95 mass% of at least one selected from SiO2, Al2O3, and B2O3.

[0090] In terms of mole% on an oxide basis, glass GD preferably contains: 55% to 75% of SiO2, 5% to 20% of Al2O3, 0% to 15% of B2O3, 0% to 30% of MgO, 0% to 30% of CaO, 0% to 30% of SrO, 0% to 30% of BaO, 0% to 25% of Na2O, 0% to 25% of K2O, and 0% to 25% of Li2O.

[0091] (Method for manufacturing glass)

[0092] In this embodiment, glass G is ground using the abrasive 1 as described above to manufacture glass G. Figure 2 It is a schematic diagram for explaining the method for manufacturing the glass of this embodiment. As Figure 2 shown, in the manufacturing method of this embodiment, first, glass G before grinding is prepared (step S10). For example, the glass manufactured by any method such as the melt casting method is cut into a specified size, and the cut glass is thinned (lightweighted) to prepare glass G before grinding. As a method for thinning, for example, a method of dry grinding the cut glass with a grindstone can be cited. However, the method for preparing glass G before grinding is not limited to the above description and is arbitrary.

[0093] After preparing the glass G before polishing, a cerium oxide polishing step (step S12) is performed on the glass G before polishing. In the cerium oxide polishing step, the glass G is polished using a cerium oxide abrasive A1 as an abrasive. The cerium oxide abrasive A1 is an abrasive containing cerium oxide as abrasive grains and water. In the cerium oxide polishing step, the glass G is polished using a polishing apparatus D having a polishing pad Da on its surface. In the cerium oxide polishing step, the liquid cerium oxide abrasive A1 is supplied to the surface of the glass G and the polishing pad Da is rotated while pressing the polishing pad Da against the surface of the glass G, thereby polishing the surface of the glass G. By polishing the surface of the glass G using the cerium oxide abrasive A1, the surface roughness Ra (arithmetic mean roughness) of the surface of the polished glass G is set within a range of, for example, 0.2 nm to 0.6 nm. It should be noted that in the cerium oxide polishing step, at least one of one surface Ga of the glass G and the surface Gb on the side opposite to the surface Ga is polished. In addition, after performing the cerium oxide polishing step, the glass G can be cleaned by the same method as that in step S16 described later. In addition, in the cerium oxide polishing step, it is not limited to polishing the glass G using the polishing apparatus D having the structure shown in Figure 2 As long as the cerium oxide abrasive A1 is used, the glass G can be polished by any method.

[0094] After polishing the glass G using the cerium oxide abrasive A1, a silica polishing step (step S14) is performed on the glass G polished using the cerium oxide abrasive A1. In the silica polishing step, the glass G is polished using a silica abrasive A2 as an abrasive. The silica abrasive A2 is an abrasive containing silica as abrasive grains and water. As the silica, colloidal silica can be used. In the silica polishing step, the glass G is polished using the polishing apparatus D. In the silica polishing step, the liquid silica abrasive A2 is supplied to the surface of the glass G and the polishing pad Da is rotated while pressing the polishing pad Da against the surface of the glass G, thereby polishing the surface of the glass G. By polishing the surface of the glass G using the silica abrasive A2, the surface roughness Ra of the surface of the polished glass G is within a range of, for example, 0.1 nm to 0.3 nm. It should be noted that in the silica polishing step, at least one of one surface Ga of the glass G and the surface Gb is polished. In addition, in the silica polishing step, it is not limited to polishing the glass G using the polishing apparatus D, and as long as the silica abrasive A2 is used, the glass G can be polished by any method.

[0095] After grinding the glass G using the silica abrasive A2, the glass G is cleaned (step S16). In step S16, the glass G that has been ground using the silica abrasive A2 is placed in a cleaning container E for cleaning. For example, the cleaning container E is filled with a liquid such as water inside, and the liquid is aerated by an aeration device. The glass G is cleaned by being immersed in the liquid in the cleaning container E and being aerated using the aeration device. However, the cleaning method of the glass G is not limited to this and can be arbitrary. In addition, the cleaning of the glass G is not essential.

[0096] After cleaning the glass G, a grinding step is performed on the cleaned glass G (step S18). In the grinding step, the glass G is ground using the abrasive 1, but a test grinding step can also be set in advance under the same conditions as the grinding step. In the grinding step, the glass G is ground using a grinding device D1. The grinding device D1 includes, for example, a cylindrical grinding pad D1a. The side surface of the grinding pad D1a is pressed against the surface of the glass G, and the grinding pad D1a is relatively moved with respect to the glass G in a direction along the surface of the glass G, thereby grinding the surface of the glass G. In the grinding step, the surface of the glass G is ground by supplying the liquid abrasive 1 to the surface of the glass G and relatively moving the grinding pad D1a while pressing the grinding pad D1a against the surface of the glass G. By grinding the surface of the glass G using the abrasive 1, the surface roughness Ra of the surface of the ground glass G is, for example, in the range of 0.03 nm to 0.05 nm. It should be noted that in the grinding step, at least one of the surfaces Ga and Gb of the glass G is ground. It should be noted that in the grinding step, it is not limited to using a cylindrical grinding pad D1a to grind the glass. For example, a grinding device D can also be used for grinding. That is, in the grinding step, as long as the abrasive 1 is used, the glass G can be ground by any method.

[0097] In the grinding step, it is preferable to set the supply amount of the abrasive 1 to the surface of the glass G per unit time to be 1 mL / min to 30 mL / min. By setting the supply amount of the abrasive 1 to be 1 mL / min or more, a sufficient amount of abrasive grains can be supplied to the grinding pad D1a, and the surface smoothness becomes good. By setting it to 30 mL / min or less, the excessive consumption of the abrasive grains can be suppressed. In addition, in the grinding step, it is preferable to set the pressure at which the grinding pad is pressed against the surface of the glass G, that is, the pressing pressure, to be 40 g / cm 2 ~200 g / cm 2 . By setting the pressing pressure to be 40 g / cm 2 or more, the glass G can be appropriately ground. By setting it to 200 g / cm 2Hereinafter, damage formation on the surface of the glass G can be suppressed. It should be noted that the pressing force of the polishing pad in the polishing step can be set smaller than the pressing force of the polishing pad in the cerium oxide polishing step and the silica polishing step. In addition, in the polishing step, it is preferable to set the polishing time using the polishing pad to 1 minute to 10 minutes. By setting the polishing time to 1 minute or more, the glass G can be appropriately polished, and by setting it to 10 minutes or less, damage formation on the surface of the glass G can be suppressed. It should be noted that the polishing time in the polishing step can be set shorter than the polishing time in the cerium oxide polishing step and the silica polishing step.

[0098] After polishing the glass G using the abrasive 1, the glass G is cleaned (step S20). In step S20, the glass G is placed in the cleaning container E using the abrasive 1, and the glass G is cleaned in the same manner as in step S16. However, the cleaning method of the glass G in step S20 is also arbitrary, and step S20 is not an essential process.

[0099] As described above, in the present embodiment, the glass G is polished using the cerium oxide abrasive A1, the glass G polished using the cerium oxide abrasive A1 is polished using the silica abrasive A2, and the glass G polished using the silica abrasive A2 is polished using the abrasive 1. By polishing the glass G in this way, the glass G with a small surface roughness and high smoothness can be manufactured. However, the polishing process of the glass G is not limited to this. For example, the polishing using the silica abrasive A2 (step S14) may not be performed. In this case, the glass G is polished using the cerium oxide abrasive A1, and the glass G polished using the cerium oxide abrasive A1 is polished using the abrasive 1. In addition, the polishing using the cerium oxide abrasive A1 is not essential, and in the present embodiment, it is sufficient to polish the glass G using at least the abrasive 1.

[0100] Regarding the potential of the glass G, the Zeta potential at pH 6 is preferably -100 mV to 20 mV, more preferably -80 mV to 10 mV, further preferably -60 mV to 0 mV, still further preferably -40 mV to -3 mV, and most preferably -30 mV to -5 mV. By making the Zeta potential within this range, the interaction between the carbon particles contained in the abrasive 1 and the glass can be effectively exerted, and the glass can be polished while increasing the polishing amount per unit time.

[0101] The absolute value of the difference (Δζ potential) between the Zeta potential of the abrasive 1 and the glass G is preferably less than 130.0 mV, more preferably less than 58 mV, still more preferably less than 57 mV, further preferably less than 50 mV, still further preferably less than 45 mV, and most preferably less than 40 mV.

[0102] The Zeta potential of the glass G can be measured using a Zeta potentiometer by electrophoresis light scattering method. In this embodiment, the Otsuka Electronics Zeta potential measurement system ELSZ-1000Z is used. An aqueous hydrochloric acid solution or an aqueous sodium hydroxide solution is added as a pH adjuster to a 10 mmol / L aqueous sodium chloride solution, and 250 μL of a suspension containing polystyrene latex particles as monitoring particles is added thereto to prepare a measurement solution.

[0103] The ratio of the refractive index of the glass G to the surface roughness Ra (nm) of the glass G (refractive index / Ra) is preferably 28 or more and less than 100, more preferably 30 to 80, and further preferably 33 to 70. Thereby, a glass having a high refractive index and a smooth surface can be provided.

[0104] It should be noted that the refractive index here refers to the refractive index of the d line of helium (wavelength 587.6 nm), and it can be measured by the V-block method. In addition, the surface roughness Ra is the arithmetic mean roughness defined by JIS B0601 (2001). In this specification, the value is obtained by measuring a 10 μm × 10 μm area using an atomic force microscope (AFM).

[0105] (Effect)

[0106] As described above, the abrasive 1 of the first aspect of the present disclosure contains amorphous carbon 10, water 12, and an acid 14. The content of the amorphous carbon 10 is 0.005 mass% to 50 mass% with respect to the whole of the abrasive 1, and the number of acid groups contained in 1 kg of the abrasive is 0.45 mmol / kg or more. According to the present disclosure, by setting the content of the amorphous carbon 10 and the number of acid groups within the above ranges, a high level of smoothness can be achieved, the grinding of the glass G can be promoted, and the grinding rate (the amount of grinding per unit time) can be increased.

[0107] The abrasive 1 of the second aspect of the present disclosure is the abrasive 1 of the first aspect, and the number of acid groups contained in 1 kg of the abrasive is preferably 400 mmol / kg or less. By setting the number of acid groups within the above range, the grinding rate can be increased and the deterioration of workability can be suppressed.

[0108] The abrasive 1 of the third aspect of the present disclosure is the abrasive 1 of the first aspect or the second aspect, and the content of the acid 14 is preferably 0.02 mass% to 100 mass% with respect to the content of the amorphous carbon 10. By setting the content of the acid 14 within the above range, the grinding rate can be increased and the deterioration of workability can be suppressed.

[0109] The abrasive 1 of the fourth aspect of the present disclosure is any one of the abrasives 1 of the first to third aspects, and the acid 14 is preferably an organic acid. By using an organic acid, the grinding rate can be increased.

[0110] The abrasive 1 according to the fifth aspect of the present disclosure is the abrasive 1 according to the fourth aspect, and the acid 14 is preferably a chelating agent. By using a chelating agent, the polishing rate can be increased by chelation.

[0111] The abrasive 1 according to the sixth aspect of the present disclosure is the abrasive 1 according to the fourth or fifth aspect. Preferably, the acid group is a sulfonic acid group and two to four acid groups are contained in one molecule of the acid 14. By using the abrasive 1 having a sulfonic acid group, the polishing rate can be increased.

[0112] The abrasive 1 according to the seventh aspect of the present disclosure is any one of the abrasives 1 according to the first to sixth aspects. Preferably, the amorphous carbon 10 is hydrophilic. By using the hydrophilic amorphous carbon 10, the glass G can be polished appropriately.

[0113] The abrasive 1 according to the eighth aspect of the present disclosure is any one of the abrasives 1 according to the first to seventh aspects. Preferably, the average primary particle diameter of the amorphous carbon 10 is 20 nm to 500 nm. By using the amorphous carbon 10 having such a particle diameter, the glass G can be polished appropriately.

[0114] The abrasive 1 according to the ninth aspect of the present disclosure is any one of the abrasives 1 according to the first to eighth aspects. Preferably, the average dispersion diameter of the amorphous carbon 10 is 100 nm to 200 nm and the Zeta potential is -80 mV to -5 mV. By using the amorphous carbon 10 having such properties, the polishing rate can be increased.

[0115] The abrasive 1 according to the tenth aspect of the present disclosure is any one of the abrasives 1 according to the first to ninth aspects. Preferably, it is used for glass polishing. The abrasive 1 can increase the polishing rate of glass.

[0116] The glass plate (glass) according to the eleventh aspect of the present disclosure is polished using any one of the abrasives 1 according to the first to tenth aspects. According to the present disclosure, a properly polished glass plate can be obtained.

[0117] The glass plate (glass) according to the twelfth aspect of the present disclosure is the glass plate according to the eleventh aspect. Preferably, the absolute value of the difference (Δζ potential) between the Zeta potential of the amorphous carbon and the Zeta potential of the glass plate is less than 57.0 mV. According to the present disclosure, a properly polished glass plate can be obtained.

[0118] The glass plate (glass) according to the thirteenth aspect of the present disclosure is the glass plate according to the eleventh or twelfth aspect. Preferably, the refractive index is 1.8 or more. According to the present disclosure, a properly polished glass plate with a high refractive index can be obtained.

[0119] The glass grinding method of the 14th aspect of the present disclosure is to grind glass using any one of the abrasives 1 in the 1st to 10th aspects. According to this method, by using the abrasive 1, the grinding rate of the glass can be increased.

[0120] The glass grinding method of the 15th aspect of the present disclosure is the glass grinding method of the 14th aspect, including: a cerium oxide grinding step of grinding glass with a cerium oxide abrasive containing cerium oxide; and a grinding step of grinding glass with the abrasive 1 after the cerium oxide grinding step. According to this method, the grinding rate of the glass can be increased and the glass can be properly ground.

[0121] The glass grinding method of the 16th aspect of the present disclosure is the glass grinding method of the 14th aspect, further including a silica grinding step of grinding glass with a silica abrasive containing silica after the cerium oxide grinding step, and grinding the glass with the abrasive 1 after the silica grinding step. According to this method, the grinding rate of the glass can be increased and the glass can be properly ground.

[0122] The glass manufacturing method of the 17th aspect of the present disclosure is to manufacture glass using any one of the grinding methods in the 12th to 16th aspects. According to this method, glass can be properly manufactured.

[0123] (Example)

[0124] Next, the examples will be described. It should be noted that the embodiments can be changed within the scope of achieving the effects of the invention. Tables 1 and 2 are tables showing the conditions and evaluation results of each example. It should be noted that Glass A is the composition of Glass GA described in the above embodiments.

[0125] More specifically, in terms of mol% based on oxide basis, Glass A contains: 15% of SiO2, 25% of B2O3, 6% of ZrO2, 24% of TiO2, 4% of Nb2O5, and 23% of La2O3.

[0126]

[0127]

[0128] (Example 1)

[0129] (Glass)

[0130] In Example 1, glass with a length of the first side of 50 mm, a length of the second side intersecting the first side of 50 mm, and a thickness of 1.0 mm was prepared. Glass A was used as the glass.

[0131] (Abrasive)

[0132] In Example 1, a polishing agent containing amorphous carbon (manufactured by Tokai Carbon Co., Ltd.) as abrasive grains, water, and an acid was prepared. The characteristics of the polishing agent of Example 1 are shown in Table 1. That is, HEDP (CHELEST PH-210 manufactured by CHELEST Co., Ltd.), which is an organic acid and a chelating agent, was used as the acid. The content (concentration) of amorphous carbon in the whole polishing agent was 1% by mass, the content of the acid relative to the amount of amorphous carbon (addition amount vs. abrasive grains) was 10% by mass, and the number of acid groups per 1 kg of the polishing agent was 9.71 mmol / kg. Amorphous carbon, water (pure water), and an acid (HEDP) were mixed to obtain the polishing agent of Example 1. It should be noted that in Example 1, since HEDP was used as the acid, the acid group was a sulfonic acid group, and 2 to 4 sulfonic acid groups were contained in one molecule of the acid. In addition, the amorphous carbon in Example 1 was hydrophilic.

[0133] In addition, the Zeta potential of the amorphous carbon in the polishing agent and the Zeta potential of the glass were measured by the same method as in the present embodiment. The ΔZeta potential represents the difference between the Zeta potential of the amorphous carbon and the Zeta potential of the glass. The measurement results are shown in Table 1.

[0134] (Polishing conditions)

[0135] In Example 1, the prepared glass was polished in three stages. As the first stage, the prepared glass was polished with a cerium oxide polishing agent A1, and the glass after polishing in the first stage was polished with a silica polishing agent A2. Then, the glass after polishing in the second stage was polished with the above polishing agent.

[0136] (First-stage polishing)

[0137] In the first-stage polishing, the prepared glass was polished with a cerium oxide polishing agent A1 under the conditions shown below. That is, FAM12BS manufactured by SPEEDFAM Co., Ltd. was used as the polishing apparatus, and a polishing agent containing 95% by weight of water and 5% by weight of cerium oxide abrasive grains manufactured by Showa Denko was used as the cerium oxide polishing agent A1. In addition, a suede pad AG8 manufactured by FILWEL Co., Ltd. was used as the polishing pad, the rotational speed of the polishing disk was set to 40 rpm, the pressing force of the polishing pad was set to 144 g / cm 2 , the polishing time was set to 30 minutes, and the supply amount of the cerium oxide polishing agent A1 was set to 5 ml / min. Hereinafter, the glass polished with the cerium oxide polishing agent A1 under such conditions is appropriately referred to as the glass after cerium oxide polishing. The surface roughness Ra of the glass after cerium oxide polishing was 0.55 nm.

[0138] (Second-stage polishing)

[0139] In the grinding in the second stage, the glass after the grinding in the first stage is ground using silica abrasive A2 under the conditions shown below. That is, FAM12BS manufactured by SPEEDFAM Co., Ltd. is used as the grinding device, and an abrasive containing 93% by weight of water and 7% by weight of colloidal silica abrasive grains manufactured by FUJIMI INCORPORATED is used as silica abrasive A2. In addition, suede pad NP787 manufactured by FILWEL Co., Ltd. is used as the grinding pad, the rotational speed of the grinding disk is set to 40 rpm, and the pressing force of the grinding pad is set to 100 g / cm 2 , the grinding time is set to 20 minutes, and the supply rate of silica abrasive A2 is set to 5 ml / min. Hereinafter, the glass ground using silica abrasive A2 under such conditions is appropriately referred to as silica-ground glass. The surface roughness Ra of the silica-ground glass is 0.15 nm.

[0140] (Grinding in the third stage)

[0141] In the grinding in the third stage, the glass after the grinding in the second stage is ground using the above-mentioned abrasive under the conditions shown below. That is, FAM12BS manufactured by SPEEDFAM Co., Ltd. is used as the grinding device, suede pad NP787 manufactured by FILWEL Co., Ltd. is used as the grinding pad, the rotational speed of the grinding disk is set to 40 rpm, and the pressing force of the grinding pad is set to 44 g / cm 2 , the grinding time is set to 1 minute, and the supply rate of the abrasive is set to 5 ml / min.

[0142] (Examples 2 to 42)

[0143] In Examples 2 to 42, except that the glass and the abrasive are as shown in Tables 1 and 2, the glass is ground using the abrasive in the same manner as in Example 1. It should be noted that glass B refers to the glass having the composition of glass GB in the above-mentioned embodiment, glass C refers to the glass having the composition of glass GC in the above-mentioned embodiment, and glass D refers to the glass having the composition of glass GD in the above-mentioned embodiment.

[0144] In addition, in terms of mol% based on oxides, glass B contains: 10% of P2O5, 7% of Nb2O5, 30.5% of Bi2O3, 26.5% of TeO2, 5.5% of ZnO, and 21.5% of B2O3.

[0145] In addition, in terms of mol% based on oxides, glass C contains: 64.5% of SiO2, 12.0% of Al2O3, 1.8% of ZrO2, 12.8% of Li2O, 5.5% of Na2O, and 3.4% of K2O.

[0146] In addition, in terms of molar % based on oxides, glass D contains: 65.8% of SiO2, 11.1% of Al2O3, 7.6% of B2O3, 5.7% of MgO, 4.9% of CaO, and 4.9% of SrO.

[0147] (Evaluation)

[0148] In the evaluation, the grinding rate, the presence or absence of white fog, and the arithmetic mean roughness Ra of the ground glass surface are evaluated. Additionally, as an optional evaluation, the ratio of the refractive index of the glass to the arithmetic mean roughness Ra (nm) of the ground glass surface is evaluated.

[0149] The grinding rate is calculated by measuring the thickness of the glass before and after grinding, and dividing the difference between the thickness of the glass before grinding and the thickness of the glass after grinding by the grinding time (here it is 1 minute).

[0150] The presence or absence of white fog is determined by visually observing while irradiating light with a high-brightness light source. When the light is irradiated perpendicularly to the glass and when the light is irradiated at an angle of 30 degrees to the glass, if there is a difference in the degree of light scattering on the glass surface and the glass appears white, it is considered to have white fog, and if there is no difference in degree, it is considered to have no white fog.

[0151] The arithmetic mean roughness Ra of the surface of the ground glass is measured by an atomic force microscope (AFM). The refractive index of the glass is measured using the method described in this embodiment.

[0152] In the evaluation, an example that simultaneously satisfies a grinding rate of 3 (nm / min) or more, no white fog, and an arithmetic mean roughness Ra of 0.05 nm or less is considered qualified, and an example that does not satisfy at least one of these is considered unqualified.

[0153] As shown in Table 1 and Table 2, it can be seen that Examples 1 to 6, Examples 10 to 16, Examples 23 to 24, Examples 27 to 28, Examples 31 to 32, Examples 36 to 37, Examples 41, and 42 of the examples are qualified, and the grinding rate of the glass can be improved and the glass can be properly ground. On the other hand, it can be seen that Comparative Examples 7 to 9, Examples 17 to 22, Examples 25 to 26, Examples 29 to 30, Examples 33 to 35, and Examples 38 to 40 are unqualified and cannot achieve the effect of improving the grinding rate of the glass and properly grinding the glass.

[0154] In addition, for example, as shown in Examples 2, 23, 27, and 31, it can be seen that the grinding agents of the examples can more appropriately improve the grinding rate of glasses with compositions such as Glass A and Glass B.

[0155] As described above, the embodiments of the present invention have been explained, but the embodiments are not limited to the content of these embodiments. In addition, among the above-described constituent elements, there are included constituent elements that can be easily conceived by those skilled in the art, constituent elements that are substantially the same, and constituent elements within the so-called equivalent range. Moreover, the above-described constituent elements can be appropriately combined. Also, various omissions, substitutions, or changes of the constituent elements can be made without departing from the gist of the above-described embodiments.

[0156] Symbol Explanation

[0157] 1 Abrasive

[0158] 10 Amorphous Carbon

[0159] 12 Water

[0160] 14 Acid

Claims

1. An abrasive, comprising amorphous carbon, water, and an acid other than a polymer system, The content of the amorphous carbon is 0.005% by mass to 50% by mass relative to the whole of the abrasive, The number of acid groups contained in each 1 kg of the abrasive is 0.45 mmol / kg or more.

2. The abrasive according to claim 1, wherein The number of acid groups contained in each 1 kg of the abrasive is 400 mmol / kg or less.

3. The abrasive according to claim 1 or 2, wherein The content of the acid is 0.02% by mass to 100% by mass relative to the content of the amorphous carbon.

4. The abrasive according to claim 1 or 2, wherein The acid is an organic acid.

5. The abrasive according to claim 4, wherein, The acid is a chelating agent.

6. The abrasive according to claim 4, wherein, The acid group is a phosphonic acid group, and 2 to 4 of the acid groups are contained in one molecule of the acid.

7. The abrasive according to claim 1 or 2, wherein The amorphous carbon is hydrophilic.

8. The abrasive according to claim 1 or 2, wherein, The average primary particle diameter of the amorphous carbon is 20 nm to 500 nm.

9. The abrasive according to claim 1 or 2, wherein The average dispersion diameter of the amorphous carbon is 100 nm to 200 nm, and the Zeta potential is -80 mV to -5 mV.

10. The abrasive according to claim 1 or 2, which is used for glass grinding.

11. A glass plate that has been ground using the abrasive according to claim 10.

12. The glass plate according to claim 11, wherein, The absolute value of the difference (Δζ potential) between the Zeta potential of the amorphous carbon and the Zeta potential of the glass plate is less than 57.0 mV.

13. The glass plate according to claim 11, wherein, The refractive index of the glass plate is 1.8 or more.

14. A method for grinding glass, which grinds glass using the abrasive according to claim 1 or 2.

15. The grinding method of glass according to claim 14, wherein, It includes the following steps: A cerium oxide grinding step of grinding the glass with a cerium oxide abrasive containing cerium oxide; and A grinding step of grinding the glass with the abrasive after the cerium oxide grinding step.

16. The grinding method of glass according to claim 15, wherein, It further includes a silica grinding step of grinding the glass with a silica abrasive containing silica after the cerium oxide grinding step, and grinding the glass with the abrasive after the silica grinding step.

17. A method for manufacturing glass, which manufactures glass using the method for grinding glass according to claim 14.

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