JP7670231B2 - Cerium-based abrasive, polishing liquid, method for producing polishing liquid, and method for polishing glass - Google Patents

Description

The present invention relates to a cerium-based abrasive, abrasive liquid, a method for producing the abrasive liquid, and a method for polishing glass, which are used for polishing glass materials such as glass substrates used in liquid crystal panels, hard disks, filters for cutting specific frequencies, and glass substrates for optical lenses.

Glass materials are used for a variety of purposes, and surface polishing may be required depending on the application. In particular, glass materials such as glass substrates used in liquid crystal panels, hard disks, and filters for cutting specific frequencies, and glass substrates for optical lenses, require surface polishing with a high degree of smoothness and high efficiency.

In the surface polishing of glass materials, which require such excellent polishing performance, cerium-based abrasives, such as those described in Patent Documents 1 and 2, are widely used.

International Publication No. 2005/042661 International Publication No. 2002/031079

Cerium-based abrasives are generally used as glass abrasives, and many of them contain lanthanum. Cerium-based abrasives are generally used in the form of a slurry dispersed in water. This slurry is neutral to alkaline, and depending on the user, it can irritate the skin, causing symptoms such as rough skin and dermatitis. For this reason, there was a demand for a cerium-based abrasive that is easier to handle and causes less skin irritation.

The present invention has been made to solve the above-mentioned problems, and aims to provide a cerium-based abrasive, a polishing liquid, a method for manufacturing a polishing liquid, and a method for polishing glass that suppress the occurrence of rough skin and dermatitis.

The present invention is based on the discovery that in a cerium abrasive containing mixed rare earth abrasive particles containing lanthanum and cerium, the oxide-equivalent content of the cerium in the oxide-equivalent content (TREO) of all rare earth elements is 55.0 mass% or more, and the amount of lanthanum dissolved in a mixed liquid containing the cerium-based abrasive and obtained by a specified method is 40 mg/L or less, thereby reducing rough skin and dermatitis that occurs when the mixed liquid adheres to the skin.

That is, the present invention provides the following [1] to [16].
[1] A cerium-based abrasive containing mixed rare earth abrasive particles containing lanthanum and cerium,
The content of the cerium in terms of oxide in the total rare earth element content in terms of oxide (TREO) is 55.0 mass% or more,
A 100 mL polyethylene container is charged with 10 g of the cerium-based abrasive, 40 g of pure water, and 130 g of zirconia beads having a particle size of 1 mm. The cerium-based abrasive is pulverized using a ball mill stand at a container rotation speed of 210 rpm for 30 minutes to obtain a mixed liquid having a dissolved amount of lanthanum of 40 mg/L or less.
[2] The cerium-based abrasive according to the above [1], further comprising a lanthanum dissolution inhibitor.
[3] A first agent containing the mixed rare earth abrasive particles;
A second agent containing a lanthanum dissolution inhibitor;
The cerium-based abrasive according to the above [1], which is a two-component type containing
[4] The cerium-based abrasive according to the above [1], containing 0.1 to 10 mass % of fluorine atoms.
[5] The cerium-based abrasive according to the above [1], wherein the content of the lanthanum in the TREO calculated as an oxide is 0.01 to 45.0 mass %.
[6] The cerium-based abrasive according to [2] or [3] above, wherein the lanthanum dissolution inhibitor is at least one selected from the group consisting of alkali metal carbonates, alkali metal phosphates, alkali metal hydroxides, alkali metal sulfates, alkali metal nitrates, alkali metal organic acid salts, alkaline earth metal carbonates, alkaline earth metal phosphates, alkaline earth metal hydroxides, alkaline earth metal sulfates, alkaline earth metal nitrates, alkaline earth metal organic acid salts, ammonium carbonates, ammonium phosphates, ammonium hydroxides, ammonium sulfates, ammonium nitrates, and ammonium organic acid salts.
[7] The cerium-based abrasive according to the above [6], wherein the lanthanum dissolution inhibitor is at least one selected from the group consisting of alkaline earth metal carbonates, alkaline earth metal phosphates, alkaline earth metal organic acid salts, and alkali metal carbonates.
[8] The cerium-based abrasive according to the above [2] or [3], wherein the molecular weight of the lanthanum dissolution inhibitor is 300 or less.
[9] The cerium-based abrasive according to the above [2] or [3], containing 0.001 to 0.9 parts by mass of the lanthanum dissolution inhibitor per 100 parts by mass of the mixed rare earth abrasive particles.
[10] A polishing liquid comprising the cerium-based abrasive according to [1] above and at least one selected from water and a water-soluble organic solvent.
[11] A method for producing the polishing liquid according to [10] above,
The cerium-based abrasive;
one or more selected from the group consisting of water and the water-soluble organic solvent;
and (I) mixing the above to form a slurry.
[12] The method for producing a polishing liquid according to the above [11], wherein the cerium-based abrasive contains the lanthanum dissolution inhibitor.
[13] A method for producing the polishing liquid according to [10] above,
The cerium-based abrasive;
The lanthanum dissolution inhibitor;
one or more selected from the group consisting of water and the water-soluble organic solvent;
and (II) mixing the above to form a slurry.
[14] A method for producing the polishing liquid according to [10] above,
The cerium-based abrasive;
one or more selected from the group consisting of water and the water-soluble organic solvent;
(III) mixing the above to form a slurry;
The slurry obtained in the step (III) is
A method for producing a polishing liquid, comprising: a step (IV) of adding and mixing the lanthanum dissolution inhibitor.
[15] The method for producing a polishing liquid according to the above [14], wherein the cerium-based abrasive does not contain the dissolution inhibitor.
[16] A method for polishing glass, comprising using the polishing liquid according to [10] above.

According to the present invention, it is possible to provide a cerium-based abrasive, an abrasive liquid, a method for producing an abrasive liquid, and a method for polishing glass, which suppress the occurrence of rough skin and dermatitis.

Hereinafter, embodiments of the cerium-based abrasive, the polishing liquid, the method for producing the polishing liquid, and the method for polishing glass of the present invention will be described in detail.
In this specification, the terms "50% particle size in a cumulative particle size distribution based on volume" and " _D50 " refer to the particle size at 50% in a cumulative particle size distribution based on volume, determined from a particle size distribution measured by a laser diffraction/scattering method. Specifically, the value is measured using a Microtrack particle size distribution analyzer described in the Examples below.

[Cerium-based abrasive]
The cerium-based abrasive of this embodiment is a cerium-based abrasive containing mixed rare earth abrasive particles containing lanthanum and cerium, and the content of the cerium oxide ( _CeO2 ) converted into the oxide content of all rare earth elements (TREO; abbreviation for Total Rare Earth Oxides) (hereinafter referred to as `` _CeO2 amount/TREO'') is 55.0 mass% or more.
Then, 10 g of the cerium-based abrasive and 40 g of pure water are placed in a 100 mL polyethylene container, along with 130 g of zirconia beads having a particle size of 1 mm. The cerium-based abrasive is pulverized using a ball mill stand at a container rotation speed of 210 rpm for 30 minutes, resulting in a mixed liquid in which the amount of lanthanum dissolved is 40 mg/L or less.

The TREO in the cerium-based abrasive of this embodiment is derived from mixed rare earth abrasive particles.
From the viewpoint of improving the polishing rate, the content of TREO in the mixed rare earth abrasive particles is preferably 85.0% by mass or more, more preferably 90.0% by mass or more, and even more preferably 92.0% by mass or more, and from the viewpoint of further improving the polishing rate by containing elements other than the elements constituting TREO and suppressing the occurrence of surface defects on the polished surface, the content of TREO is preferably 99.0% by mass or less, more preferably 98.0% by mass or less, and even more preferably 95.0% by mass or less.

The content of cerium oxide ( _CeO2 ) in TREO ( _CeO2 amount/TREO) is 55.0 mass% or more, and from the viewpoint of improving the polishing rate, it is preferably 60.0 mass% or more, more preferably 62.0 mass% or more, and even more preferably 64.0 mass% or more. Also, from the viewpoint of ensuring the content of rare earth elements other than Ce and suppressing the occurrence of surface defects on the polished surface, the CeO2 _amount /TREO is preferably 90.0 mass% or less, more preferably 80.0 mass% or less, even more preferably 75.0 mass% or less, and even more preferably 70.0 mass% or less.

The content of lanthanum oxide ( _La2O3 ) in TREO (hereinafter referred to as _La2O3 amount/TREO) is preferably _0.01 mass% or more, more preferably _1.0 mass% or more, even more preferably 10.0 mass% or more, still more preferably 20.0 mass% or more, and even more preferably 30.0 mass% or more from the viewpoint of suppressing the occurrence of scratches on the polished surface. _{The La2O3} amount/TREO is 45.0 mass% or less because the Ce amount in TREO is 55.0 mass% or more, and is preferably 40.0 mass% or less, more preferably 37.0 mass% or less, and even more preferably 35.0 mass% or less from the viewpoint of improving the polishing rate and further reducing rough skin and dermatitis.

The TREO can be measured by oxalate precipitation, calcination and gravimetric methods, specifically, by the method described in the examples below.
In addition, the content of each rare earth element such as Ce or La can be measured by instrumental analysis such as high-frequency inductively coupled plasma (ICP) analysis or X-ray fluorescence analysis. In this embodiment, the oxide equivalent amount is the value obtained by converting each rare earth element into an oxide from the measured value by ICP atomic emission spectrometry (ICP-AES).

The reason why the cerium-based abrasive of the present embodiment can suppress rough skin and dermatitis is not clear, but is thought to be as follows.
Lanthanum contained in cerium-based abrasives is dissolved as lanthanum ions in water or water-soluble organic solvents during the manufacture of cerium-based abrasives or when slurried. If the amount of lanthanum dissolved in the liquid is large, it will combine with chloride ions derived from the raw materials of the cerium-based abrasives to produce highly toxic lanthanum chloride, which will adhere to the skin of the human body and cause rough skin and dermatitis. On the other hand, by setting the amount of lanthanum dissolved to a low concentration of 40 mg/L or less, the production of lanthanum chloride, etc. is suppressed, and as a result, it is thought that the occurrence of rough skin and dermatitis is suppressed.

The amount of lanthanum dissolved in the mixed solution obtained by the above-mentioned specified method is 40mg/L or less, and from the viewpoint of suppressing the occurrence of rough skin and dermatitis, it is preferably 35mg/L or less, more preferably 30mg/L or less, and even more preferably 25mg/L or less, and from the viewpoint of cost, it is preferably 0.1mg/L or more, more preferably 0.5mg/L or more, and even more preferably 1.0mg/L or more. When the cerium-based abrasive of this embodiment is used in a slurry state in an actual machine, the ratio of the cerium-based abrasive to the dispersion medium water and water-soluble organic solvent in the slurry may differ from that in the above-mentioned specified method, but the effect of this embodiment is manifested as long as it is below the lanthanum dissolved concentration measured by the measurement method.
In this specification, the "amount of dissolved lanthanum" is a value calculated from ICP analysis, specifically, a value calculated by the method described in the following examples.

During the production of a cerium-based abrasive or when it is made into a slurry, chloride ions derived from the raw materials of the cerium-based abrasive dissolve in water, a water-soluble organic solvent, or the like together with lanthanum ions.
The amount of dissolved chlorine in the mixed solution obtained by the above-mentioned specified method is preferably 40 mg/L or less, more preferably 35 mg/L or less, and even more preferably 25 mg/L or less, from the viewpoint of further suppressing the occurrence of rough skin and dermatitis, and is preferably 0.1 mg/L or more, more preferably 0.5 mg/L or more, and even more preferably 1.0 mg/L or more, from the viewpoint of cost.
In this specification, the "amount of dissolved chlorine" is a value calculated from IC analysis, specifically, a value calculated by the method described in the following examples.

The particle size ( _D50 ) of the cerium-based abrasive of this embodiment is preferably 0.10 μm or more, more preferably 0.3 μm or more, even more preferably 0.5 μm or more, and even more preferably 0.7 μm or more, from the viewpoint of producing the cerium-based abrasive with good productivity, and from the viewpoint of obtaining excellent polishing performance that can reduce polishing scratches and satisfactorily smooth the polished surface, _D50 is preferably 10.0 μm or less, more preferably 5.0 μm or less, and even more preferably 3.0 μm or less.

The specific surface area of the cerium-based abrasive of this embodiment is preferably 1.0 m ² /g or more, more preferably 2.0 m ² /g or more, and even more preferably 3.0 m ² /g or more, from the viewpoint of suppressing the occurrence of scratches on the polishing surface, and is preferably 10.0 m 2 /g or less, more preferably 8.0 m ² /g or less, even more preferably 7.0 m ² /g or less, and even more preferably 6.0 m ² /g or less, from the viewpoint of improving the ^polishing rate.
In this specification, the specific surface area is a value measured by the BET method (single point method).

The cerium-based abrasive of this embodiment may contain fluorine atoms from the viewpoint of improving the polishing rate.
When the cerium-based abrasive contains fluorine atoms, the fluorine atom content in the cerium-based abrasive is preferably 0.1 mass % or more, more preferably 1.0 mass % or more, and even more preferably 3.0 mass % or more from the viewpoint of improving the polishing rate, and is preferably 10.0 mass % or less, more preferably 9.0 mass % or less, even more preferably 8.0 mass % or less, and even more preferably 7.0 mass % or less from the viewpoint of suppressing the occurrence of scratches on the polished surface.
The fluorine atom content in the cerium-based abrasive can be measured by melting the cerium-based abrasive in an alkali to prepare an aqueous solution, and then subjecting the solution to an ion electrode method.

In the cerium-based abrasive of this embodiment, the TREO is preferably 85.0% by mass or more, more preferably 90.0% by mass or more, and even more preferably 92.0% by mass or more, from the viewpoint of improving the polishing rate, and from the viewpoint of containing elements other than the elements constituting the TREO to further improve the polishing rate and to suppress the occurrence of surface defects (fine surface irregularities) on the polishing surface, the TREO is preferably 99.0% by mass or less, more preferably 97.0% by mass or less, and even more preferably 96.0% by mass or less.

(Mixed rare earth abrasive particles)
In the present embodiment, the "mixture" of the mixed rare earth abrasive particles means that it contains a plurality of rare earth elements.The mixed rare earth abrasive particles may contain rare earth elements other than Ce and La (lanthanum).The rare earth elements include, for example, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, etc.

The particle size ( _D50 ) of the mixed rare earth abrasive particles of this embodiment is preferably 0.10 μm or more, more preferably 0.3 μm or more, even more preferably 0.5 μm or more, and even more preferably 0.7 μm or more, from the viewpoint of producing a cerium-based abrasive with good productivity, and is preferably 10.0 μm or less, more preferably 5.0 μm or less, and even more preferably 3.0 μm or less, from the viewpoint of obtaining excellent polishing performance that can reduce polishing scratches and satisfactorily smooth the polished surface.

The specific surface area of the mixed rare earth abrasive particles of this embodiment is preferably 1.0 m ² /g or more, more preferably 2.0 m ² /g or more, and even more preferably 3.0 m ² /g or more, from the viewpoint of suppressing the occurrence of scratches on the polishing surface, and is preferably 10.0 m 2 /g or less, more preferably 8.0 m ² /g or less, even more preferably 7.0 ^{m 2} /g or less, and even more preferably 6.0 m ² / ^g or less, from the viewpoint of improving the polishing rate.
In this specification, the specific surface area is a value measured by the BET method (single point method).

The mixed rare earth abrasive particles of this embodiment may contain fluorine atoms from the viewpoint of improving the polishing rate.
When the mixed rare earth abrasive particles contain fluorine atoms, the fluorine atom content in the mixed rare earth abrasive particles is preferably 0.1 mass% or more, more preferably 1.0 mass% or more, and even more preferably 3.0 mass% or more from the viewpoint of improving the polishing rate, and is preferably 10.0 mass% or less, more preferably 9.0 mass% or less, even more preferably 8.0 mass% or less, and even more preferably 7.0 mass% or less from the viewpoint of suppressing the occurrence of scratches on the polished surface.

(Lanthanum dissolution inhibitor)
The cerium-based abrasive of this embodiment may contain, in addition to the mixed rare earth abrasive particles, a lanthanum dissolution inhibitor that inhibits the dissolution of lanthanum.
As the lanthanum dissolution inhibitor, a compound having the effect of converting lanthanum ions dissolved in water or a water-soluble organic solvent, etc., into an insoluble salt, etc., and precipitating the salt, or a compound having the effect of immobilizing lanthanum ions by a chelating action, is preferred.
Such a lanthanum dissolution inhibitor is preferably one or more selected from alkali metal carbonates, alkali metal phosphates, alkali metal hydroxides, alkali metal sulfates, alkali metal nitrates, alkali metal organic acid salts, alkaline earth metal carbonates, alkaline earth metal phosphates, alkaline earth metal hydroxides, alkaline earth metal sulfates, alkaline earth metal nitrates, alkaline earth metal organic acid salts, ammonium carbonates, ammonium phosphates, ammonium hydroxides, ammonium sulfates, ammonium nitrates, and ammonium organic acid salts, and from the viewpoint of the safety of the salts produced, more preferably one or more selected from alkaline earth metal carbonates, alkaline earth metal phosphates, alkaline earth metal organic acid salts, and alkali metal carbonates.

As the alkali metal, from the viewpoint of the safety of the salt to be produced, sodium and potassium are preferred, and sodium is more preferred.
From the same viewpoint, calcium and magnesium are preferred as the alkaline earth metal.
Specific examples of preferred lanthanum dissolution inhibitors include monocalcium phosphate, dicalcium phosphate, calcium hydroxide, calcium carbonate, calcium gluconate, calcium citrate, sodium bicarbonate, ammonium bicarbonate, dimagnesium phosphate, dicalcium phosphate, and the like. Of these, dicalcium phosphate is more preferred from the viewpoints of further suppressing the occurrence of rough skin and dermatitis, the safety of the salt produced, and suppressing the occurrence of scratches on the polishing surface.
The lanthanum dissolution inhibitor may be used alone or in combination of two or more kinds.

From the viewpoint of further suppressing the occurrence of rough skin and dermatitis, the molecular weight of the lanthanum dissolution inhibitor is preferably 50 or more, more preferably 75 or more, even more preferably 100 or more, and is preferably 300 or less, more preferably 200 or less, even more preferably 150 or less. A molecular weight of 300 or less is preferred because it has high reactivity with lanthanum ions and is highly effective in suppressing lanthanum dissolution.

When the cerium-based abrasive of this embodiment contains a lanthanum dissolution inhibitor, the cerium-based abrasive may be a one-component type that already contains the lanthanum dissolution inhibitor, or it may be a two-component type that contains a first component containing the mixed rare earth abrasive particles and a second component containing the lanthanum dissolution inhibitor.

When the cerium-based abrasive is a two-component type containing a first agent containing the mixed rare earth abrasive particles and a second agent containing a lanthanum dissolution inhibitor, etc., the content of the mixed rare earth abrasive particles in the first agent is preferably 85.0% by mass or more, more preferably 90.0% by mass or more, and even more preferably 92.0% by mass or more from the viewpoint of improving the polishing rate, and is preferably 99.9% by mass or less, more preferably 99.5% by mass or less, and even more preferably 99.2% by mass or less from the viewpoint of suppressing the occurrence of rough skin and dermatitis.

The content of the lanthanum dissolution inhibitor in the cerium-based abrasive, in both the single-component type and the double-component type, is preferably 0.95 parts by mass or less, more preferably 0.85 parts by mass or less, and even more preferably 0.75 parts by mass or less, based on 100 parts by mass of mixed rare earth abrasive particles, from the viewpoint of cost.Furthermore, from the viewpoint of suppressing the occurrence of rough skin and dermatitis, it is preferably 0.001 parts by mass or more, more preferably 0.01 parts by mass or more, and even more preferably 0.1 parts by mass or more.
In addition, the content of the lanthanum dissolution inhibitor in the cerium-based abrasive is preferably 0.95% by mass or less, more preferably 0.90% by mass or less, even more preferably 0.80% by mass or less, and even more preferably 0.70% by mass or less, in terms of cost, in both the one-component type and two-component type. In addition, in terms of suppressing the occurrence of rough skin and dermatitis, it is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, even more preferably 0.05% by mass or more, and even more preferably 0.1% by mass or more.
It is.

(Additives)
In the cerium-based abrasive of this embodiment, additives such as glycols such as ethylene glycol and polyethylene glycol, polymer dispersants such as sodium salt of polyacrylic acid, polycarboxylic acid polymer, polysulfonic acid polymer, cellulose ethers such as methyl cellulose and carboxymethyl cellulose, water-soluble polymers such as polyvinyl alcohol, phosphoric acid compounds, etc. may be added to improve dispersibility, prevent sedimentation, prevent solidification, improve stability and improve workability. These may be used alone or in combination of two or more. When additives are added, polymer dispersants, phosphoric acid compounds, and cellulose ethers are preferred from the viewpoint of improving dispersibility, preventing sedimentation, preventing solidification, improving stability and improving workability.
Examples of polymer dispersants include poly(meth)acrylic acid, polyhydroxy(meth)acrylic acid, (meth)acrylic acid copolymers such as copolymers of (meth)acrylic acid and maleic acid, copolymers of olefin and maleic acid, copolymers of maleic acid and alkylene oxide adducts of allyl alcohol such as ethylene oxide or propylene oxide, copolymers of allylsulfonic acid and maleic acid, etc., or alkali metal salts such as sodium salts and potassium salts thereof. Among these, polyacrylic acid, copolymers of acrylic acid and maleic acid, or alkali metal salts thereof are preferred, copolymers of acrylic acid and maleic acid or alkali metal salts thereof are more preferred, and sodium salts of copolymers of acrylic acid and maleic acid are even more preferred.
Examples of phosphoric acid compounds include inorganic phosphoric acids such as tripolyphosphoric acid, pyrophosphoric acid, tetrametaphosphoric acid, hexametaphosphoric acid, orthophosphoric acid, and phosphorous acid; organic phosphonic acids such as aminotrimethylenephosphonic acid, 1-hydroxyethylidene-1,1-diphosphonic acid, ethylenediaminetetramethylenephosphonic acid, and diethylenetriaminepentamethylenephosphonic acid; and alkali metal salts thereof such as sodium salts and potassium salts. Among these, tripolyphosphoric acid, pyrophosphoric acid, hexametaphosphoric acid, and alkali metal salts thereof are preferred, and sodium tripolyphosphate is more preferred.

When the cerium-based abrasive contains an additive, the content of the additive per 100 parts by mass of the mixed rare earth abrasive particles is, from the viewpoints of improving dispersibility, preventing sedimentation, preventing solidification, improving stability, and improving workability, preferably 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, even more preferably 0.3 parts by mass or more, and even more preferably 0.5 parts by mass or more, and from the viewpoint of cost, is preferably 10.0 parts by mass or less, more preferably 5.0 parts by mass or less, and even more preferably 3.0 parts by mass or less.
Furthermore, when the cerium-based abrasive contains an additive, the content of the additive in the cerium-based abrasive is preferably 0.01 mass % or more, more preferably 0.1 mass % or more, even more preferably 0.3 mass % or more, and still more preferably 0.5 mass % or more, from the viewpoint of improving dispersibility, preventing sedimentation, preventing solidification, improving stability, and improving workability, and is preferably 10.0 mass % or less, more preferably 5.0 mass % or less, and even more preferably 3.0 mass % or less, from the viewpoint of cost.

[Method of manufacturing cerium-based abrasive]
The method for producing cerium-based abrasive is not particularly limited, but specifically, it is preferable to produce cerium-based abrasive by going through the process (1) of preparing mixed light rare earth compound, the process (2) of producing mixed rare earth oxide raw material from mixed light rare earth compound, and the process (3) of wet grinding the mixed rare earth oxide raw material, followed by calcination, crushing and classification to obtain mixed rare earth abrasive particles.In addition, from the viewpoint of further suppressing the occurrence of rough skin and dermatitis, it is more preferable to produce cerium-based abrasive by further adding and mixing lanthanum dissolution inhibitor after the process (3), or by going through the process (4) of preparing a second agent containing lanthanum dissolution inhibitor.The "mixing" referred to here is also synonymous with the "mixing" of the above-mentioned mixed rare earth abrasive particles.
Each step will be described in order below.

(Step (1))
In step (1), a mixed light rare earth compound is prepared.
The method for preparing the mixed light rare earth compound is not particularly limited. The mixed light rare earth compound can be obtained, for example, by separating and reducing impurities other than rare earth elements and medium and heavy rare earths from ore containing rare earth elements by chemical treatment. As the mixed light rare earth compound, it is preferable that the content of non-rare earth impurities such as alkali metals, alkaline earth metals, and radioactive substances, as well as the content of medium and heavy rare earths is reduced.
In this specification, medium and heavy rare earths refer to rare earth elements having atomic numbers greater than that of Pm, and rare earth elements other than medium and heavy rare earths are referred to as light rare earths.
As the ore containing rare earth elements, for example, rare earth concentrates obtained from raw material ores such as natural monazite and bastnaesite, which contain a large amount of Ce, are suitably used.

In the preparation of the mixed light rare earth compound, roasting with sulfuric acid is a common chemical treatment method for reducing the content of impurities. The roasting with sulfuric acid is a method in which the pulverized raw ore is roasted with sulfuric acid to generate sulfates (rare earth sulfates), which are dissolved in water to obtain a rare earth sulfate solution, and the impurities, which are insoluble, are removed by filtration or the like. The content of the impurities in the mixed light rare earth compound is preferably reduced to 1.0 mass% or less.
In addition, a chemical treatment method for reducing the content of medium and heavy rare earths can be carried out, for example, by adding carbonate to the rare earth sulfate solution after the sulfuric acid roasting to obtain a crude rare earth carbonate, adding hydrochloric acid to the crude rare earth carbonate to obtain a mixed rare earth chloride aqueous solution, and then performing solvent extraction using an organic solvent. In the solvent extraction, the contents of cerium, lanthanum, and other light rare earths can be adjusted as necessary using known methods such as adjusting the degree of extraction or using additives. The content of medium and heavy rare earths in the mixed light rare earth compound is preferably reduced to 1.0 mass% or less.

(Step (2))
In step (2), a mixed rare earth oxide raw material is produced from the mixed light rare earth compound.
The method for producing the mixed rare earth oxide raw material from the mixed light rare earth compound is not particularly limited. The mixed rare earth oxide raw material can be obtained, for example, by producing a mixed rare earth carbonate, which is a carbonate, using the mixed light rare earth compound and sodium carbonate, ammonium bicarbonate, or the like, and calcining the mixed rare earth carbonate.
The firing temperature when the mixed rare earth carbonate is fired to obtain a mixed rare earth oxide raw material is appropriately adjusted depending on the composition of the mixed rare earth carbonate, but is preferably 500 to 1200° C., more preferably 600 to 1100° C., and even more preferably 700 to 1000° C. The firing time is preferably 0.5 to 48 hours, more preferably 1 to 40 hours, and even more preferably 1.5 to 30 hours. The firing atmosphere is preferably air.
After firing, the mixed rare earth oxide raw material may be crushed by a mechanical method to adjust the particle size to a desired size.

Mixed rare earth oxide raw materials are commercially available, and commercially available products may be used. Mixed rare earth oxide raw materials can be obtained by calcining mixed light rare earth compounds such as mixed rare earth carbonates, mixed rare earth monooxycarbonates, mixed rare earth oxalates, and mixed rare earth hydroxides, and therefore the mixed rare earth carbonates, mixed rare earth monooxycarbonates, mixed rare earth oxalates, and the like, which are the raw materials used for producing the mixed rare earth oxide raw materials, may remain in commercially available mixed rare earth oxide raw materials.

(Step (3))
In step (3), the mixed rare earth oxide raw material is wet-pulverized, then calcined, crushed and classified to obtain mixed rare earth abrasive particles.
From the viewpoint of obtaining homogeneous mixed rare earth abrasive particles, the wet grinding is preferably carried out using a media mill such as a wet ball mill. As the dispersion medium, water, a water-soluble organic solvent, etc. are preferably used.
After the wet grinding, the mixture is dried, calcined, crushed, and classified to obtain mixed rare earth abrasive particles.
The drying, calcination, crushing and classification can be carried out in the same manner as in the conventional production of mixed rare earth abrasive particles.

From the viewpoint of sufficiently reacting the raw material to be fired by firing, the firing temperature is preferably 600 to 1200°C, more preferably 650 to 1150°C, and even more preferably 700 to 1100°C. The firing time at the target set temperature is preferably 0.1 to 10 hours, more preferably 0.5 to 6 hours, and even more preferably 0.5 to 4 hours. The firing atmosphere is preferably air.

In order to improve the polishing rate, fluorine atoms may be incorporated into the mixed rare earth abrasive particles. In this case, the method for incorporating fluorine atoms is not particularly limited, but a preferred method is to mix the mixed rare earth oxide raw material with the mixed rare earth fluoride raw material, wet grind the mixture, and then calcinate, crush and classify the mixture to obtain the mixed rare earth abrasive particles.

The method for obtaining the mixed rare earth fluoride raw material is not particularly limited, but for example, it can be obtained by adding a fluoride such as hydrofluoric acid, ammonium fluoride or acidic ammonium fluoride as a fluorine source to the mixed light rare earth compound and performing a heat treatment. From the viewpoint of obtaining a cerium-based abrasive that is homogeneous and has excellent polishing properties, the heat treatment is preferably performed at 400° C. or less. The heat treatment atmosphere is preferably air. The heat treatment time is preferably 0.1 to 10 hours, more preferably 0.5 to 5 hours, and even more preferably 1.0 to 4 hours. The firing atmosphere is preferably air.
The method of obtaining mixed rare earth abrasive particles by mixing a mixed rare earth oxide raw material with a mixed rare earth fluoride raw material is safer and less costly than the method of obtaining mixed rare earth abrasive particles by directly adding a fluoride such as ammonium fluoride or hydrofluoric acid to a mixed rare earth oxide raw material, and makes it easy to obtain mixed rare earth abrasive particles containing fluorine.

The content of TREO in the mixed rare earth fluoride raw material is preferably 75% by mass or more, more preferably 80% by mass or more, and even more preferably 82% by mass or more. The mixed rare earth fluoride raw material is preferably one in which cerium is the main component of all rare earth elements contained therein. The content of cerium in TREO in terms of oxide ( _CeO2 amount/TREO) is preferably 55.0% by mass or more, and from the viewpoint of improving the polishing rate, it is more preferably 60.0% by mass or more, even more preferably 62.0% by mass or more, and even more preferably 64.0% by mass or more. The content of CeO2 _amount /TREO is preferably 90.0% by mass or less, more preferably 80.0% by mass or less, even more preferably 75.0% by mass or less, and even more preferably 70.0% by mass or less, from the viewpoint of ensuring the content of rare earth elements other than Ce and suppressing the occurrence of surface defects on the polished surface.

The fluorine atom content in the mixed rare earth fluoride raw material is preferably 10 to 30 mass %, more preferably 15 to 30 mass %, and further preferably 20 to 30 mass %.
The amount of the mixed rare earth fluoride raw material added to the mixed rare earth oxide raw material is appropriately determined according to the fluorine atom content required for the cerium-based abrasive to be manufactured. From the viewpoint of obtaining excellent polishing properties, the amount of the mixed rare earth fluoride raw material added is preferably 1 to 40 mass%, more preferably 3 to 35 mass%, and even more preferably 5 to 30 mass%, relative to 100 mass% in total of the mixed rare earth oxide raw material and the mixed rare earth fluoride raw material.

(Step (4))
In step (4), after step (3), a lanthanum dissolution inhibitor is added to and mixed with the mixed rare earth abrasive particles obtained in step (3), or a second agent containing a lanthanum dissolution inhibitor is prepared.
In this embodiment, when the cerium-based abrasive is a one-component type, the mixed rare earth abrasive particles can be used as the cerium-based abrasive without going through step (4), or the mixed rare earth abrasive particles obtained in step (3) can be added and mixed with a lanthanum dissolution inhibitor to be used as the cerium-based abrasive. Also, if necessary, an additive can be added and mixed together with the lanthanum dissolution inhibitor.
The mixing method is not particularly limited, and for example, mixing may be performed using a mixer such as a batch mixer, or mixing may be performed using a media mill such as a ball mill or a bead mill.
In this embodiment, when the cerium-based abrasive is a two-component type, a second component containing a lanthanum dissolution inhibitor is prepared in step (4).
In this embodiment, when the cerium-based abrasive is a two-component type containing a first agent containing the mixed rare earth abrasive particles and a second agent containing a lanthanum dissolution inhibitor, the first agent containing the mixed rare earth abrasive particles and the second agent containing the lanthanum dissolution inhibitor may be prepared separately, and the first agent and the second agent may be mixed when producing the polishing liquid.
The second agent may or may not contain water, a water-soluble organic solvent, additives, and the like in addition to the lanthanum dissolution inhibitor.

[Polishing solution]
The polishing liquid of this embodiment contains the above-mentioned cerium-based abrasive and one or more selected from water and a water-soluble organic solvent. The polishing liquid preferably contains a lanthanum dissolution inhibitor from the viewpoint of further suppressing the occurrence of rough skin and dermatitis. The polishing liquid may also contain components other than the cerium-based abrasive, one or more selected from water and a water-soluble organic solvent, and the lanthanum dissolution inhibitor.
The polishing liquid of the present embodiment is a polishing liquid that suppresses rough skin, dermatitis, and the like that may occur when the polishing liquid adheres to human skin.

From the viewpoint of exhibiting good polishing performance and from the viewpoint of cost, the content of the cerium-based abrasive in the polishing liquid is preferably within the range of 0.1 to 40.0 mass%, more preferably 1.0 to 35.0 mass%, even more preferably 3.0 to 30.0 mass%, and still more preferably 5.0 to 20.0 mass%.
In addition, when preparing the polishing liquid, additives such as a pH adjuster, an antifoaming agent, and an anti-rust agent may be added as necessary, within a range that does not impair the polishing performance, taking into consideration the object to be polished and the specifications of the polishing apparatus, etc.

The polishing liquid is particularly suitable for use in the finish polishing of various glass materials and glass products, such as glass substrates for optical and magnetic disks, glass substrates for liquid crystal displays, glass substrates for color filters and photomasks, and glass substrates for optical lenses.

[Method of manufacturing the polishing liquid]
The method for producing a polishing liquid of the present invention is a method for producing a polishing liquid containing the above-mentioned cerium-based abrasive and at least one selected from water and a water-soluble organic solvent.
In one aspect of the present invention, the method for producing a polishing liquid includes a step (I) of mixing the cerium-based abrasive with at least one selected from the group consisting of water and the water-soluble organic solvent to form a slurry, in which the cerium-based abrasive may or may not contain the lanthanum dissolution inhibitor.

In addition, when the cerium-based abrasive is a two-component type containing a first agent containing mixed rare earth abrasive particles and a second agent containing a lanthanum dissolution inhibitor, step (I) is carried out using the first agent and the second agent as the cerium-based abrasive.

In step (I), the method of forming a slurry is not particularly limited. For example, the slurry may be formed by mixing with a stirrer, or the slurry may be formed using a grinding machine such as a wet ball mill, an attritor, or a bead mill.

In another aspect of the present invention, the method for producing a polishing liquid includes a step (II) of mixing the cerium-based abrasive, the lanthanum dissolution inhibitor, and at least one selected from the group consisting of water and the water-soluble organic solvent to form a slurry. In this case, the cerium-based abrasive may or may not contain the lanthanum dissolution inhibitor.
The method for forming a slurry in the step (II) is the same as the method for forming a slurry in the above step (I).

In yet another embodiment of the present invention, the method for producing a polishing liquid includes a step (III) of mixing the cerium-based abrasive with one or more selected from the group consisting of water and the water-soluble organic solvent to form a slurry, and a step (IV) of adding and mixing the lanthanum dissolution inhibitor to the slurry obtained in the step (III). The cerium-based abrasive may or may not contain the lanthanum dissolution inhibitor.
The method for forming a slurry in the step (III) is the same as the method for forming a slurry in the above step (I).

[Glass polishing method]
The method for polishing glass of the present invention is a method for performing polishing using the polishing liquid as described above.
The glass polishing method is not particularly limited except for using the polishing liquid, and can be a method using a known polishing device, etc. The polishing liquid can be used by a known method, for example, when performing finish polishing such as mirror polishing of a glass material with a single-sided polisher or a double-sided polisher.

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.
In the preparation of the mixed rare earth oxide raw material, the preparation of the mixed rare earth fluoride raw material, the examples, and the comparative examples, the TREO, the oxide-equivalent content of each rare earth element in TREO ( ₂ amounts of CeO/TREO, ₃ amounts of _La2O /TREO, ₃ amounts of _Nd2O /TREO, and ₁₁ amounts of _Pr6O /TREO), and the fluorine atom content were determined as follows.
[TREO]
Ammonia water was added to the solution in which the measurement sample was dissolved in acid. The resulting precipitate was filtered and washed to remove the alkali metal, and then dissolved in acid again. Oxalic acid was added to this solution, and the resulting precipitate was baked in air at 800°C for 2 hours, and the TREO was determined by gravimetric method. The TREO of the mixed rare earth abrasive particles was obtained from "total rare earth oxide mass obtained after baking/mixed rare earth abrasive particle mass before acid dissolution treatment", and the TREO of the cerium abrasive was obtained from "total rare earth oxide mass obtained after baking/cerium abrasive mass before acid dissolution treatment".
[Oxide-equivalent content of each rare earth element in TREO]
The measurement sample was dissolved in acid, and the amount of each rare earth element measured by ICP-AES was converted into an oxide value and the value relative to TREO was calculated.
[Fluorine atom content]
The measurement sample was fused with an alkali, extracted with hot water, and measured with a fluorine ion meter (manufactured by Horiba, Ltd.; ion electrode method).

[Preparation of mixed rare earth oxide raw material]
(Mixed rare earth oxide raw material A)
A raw material ore (rare earth concentrate) containing 47% by mass of TREO, 2% by mass of medium and heavy rare earths calculated as oxides, and 8% by mass of neodymium calculated as oxides was treated by a sulfuric acid calcination method and a solvent extraction method to reduce impurity components other than rare earth elements to 1% by mass or less and medium and heavy rare earths to 1% by mass or less calculated as oxides, thereby obtaining a mixed light rare earth compound with an adjusted rare earth element content. In this mixed light rare earth compound, the content of cerium in TREO in terms of oxide ([ _CeO2 ]) ( _CeO2 amount/TREO) was 64.7% by mass, the content of lanthanum in terms of oxide ([ _La2O3 ]) ( _{La2O3 amount} /TREO) was 34.1% by mass, the content of neodymium in terms of oxide ([ _Nd2O3 ] ₎ ( _{Nd2O3 amount} /TREO) was 0.6% by mass, and the content of _praseodymium in terms of oxide ( _{[ Pr6O11} ]) ( _Pr6O11 amount/TREO) was 0.2 _% by mass.
This mixed light rare earth compound was treated with ammonium bicarbonate to obtain a mixed rare earth carbonate having 49% by mass of TREO.
This mixed rare earth carbonate was heat-treated in a calciner in the atmosphere at 800° C. for 10 hours to obtain mixed rare earth oxide raw material A. Table 1 shows the TREO, _CeO2 amount/TREO, _La2O3 amount/TREO, _{Nd2O3 amount} /TREO, and _Pr6O11 amount/TREO of mixed _rare earth oxide raw _material A.

(Mixed rare earth oxide raw materials B to E)
Similarly to the preparation of mixed rare earth oxide raw material A, mixed light rare earth compounds were used and the treatment conditions thereof and the heat treatment conditions of the mixed rare earth carbonate were adjusted to prepare mixed rare earth oxide raw materials B to E. The TREO, _CeO2 amount/TREO, _La2O3 amount/TREO, _Nd2O3 amount/TREO, and _{Pr6O11 amount} /TREO _of mixed rare earth oxide _raw materials B to E are shown in Table 1.

[Preparation of mixed rare earth fluoride raw materials]
(Mixed rare earth fluoride raw material F)
Hydrofluoric acid was added to the mixed light rare earth compound and mixed, and then the mixture was heat-treated in air at 400° C. for 2 hours to obtain a mixed fluorinated rare earth material F. Table 2 shows the TREO, _CeO2 amount/TREO, and fluorine content of this mixed fluorinated rare earth material F.

(Mixed rare earth fluoride raw materials G to I)
Similarly to the preparation of the mixed fluorinated rare earth raw material F, the mixed light rare earth compounds were used and the treatment conditions were adjusted to prepare the mixed fluorinated rare earth raw materials G to I. The TREO, _CeO2 amount/TREO, and fluorine content of the mixed fluorinated rare earth raw materials G to I are shown in Table 2.

[Production of cerium-based abrasives]
Cerium-based abrasives were produced according to the following examples and comparative examples.
Details of the additives used in the following Examples and Comparative Examples are given below.
Additive 1: Sodium tripolyphosphate (Kanto Chemical Co., Ltd.): Molecular weight over 300 Additive 2: Sodium salt of polyacrylic acid "Poise 530" (Kao Corporation): Molecular weight over 300 Additive 3: Sodium salt of copolymer of acrylic acid and maleic acid "Poise 521" (Kao Corporation): Molecular weight over 300 Additive 4: Carboxymethylcellulose (Kanto Chemical Co., Ltd.): Molecular weight over 300 Additive 5: Crystalline cellulose "Cellulose microcrystal" (Kanto Chemical Co., Ltd.): Molecular weight over 300

Example 1
1000 kg of water and a total of 1400 kg of the mixed rare earth oxide raw material A and the mixed rare earth fluoride raw material F (mass ratio 76:24) were stirred and mixed in a slurry tank, and then mixed and pulverized for 17 hours in a wet ball mill (medium: zirconia balls with a diameter of 5 mm) to obtain a uniform mixed solution.
This mixed solution was put into a rotary kiln, dried in air at 700°C for 1 hour, and then fired at 960°C for 4 hours. The fired body obtained was allowed to cool, then crushed and classified to obtain mixed rare earth abrasive particles. Dicalcium phosphate was added as a lanthanum dissolution inhibitor to the mixed rare earth abrasive particles in an amount of 0.1 parts by mass per 100 parts by mass of the mixed rare earth abrasive particles, and mixed with a stirrer to produce a cerium-based abrasive.

(Examples 2 to 25 and Comparative Examples 1 to 5)
In Example 1, the mixed rare earth oxide raw material, the mixed rare earth fluoride raw material, the firing temperature, the lanthanum dissolution inhibitor, and additives 1 to 5 were as shown in Tables 3 and 4, except that a cerium-based abrasive was produced in the same manner.

[Measurement of physical properties of mixed rare earth abrasive particles and cerium-based abrasives]
The mixed rare earth abrasive and the cerium-based abrasive produced as described above were subjected to the following physical property measurements. The results of these physical property measurements are shown in Tables 3 and 4 below.

(Particle size distribution _D50 )
Cerium-based abrasive or mixed rare earth abrasive particles were dispersed in pure water containing a dispersant to prepare a measurement sample, and the particle size distribution of the cerium-based abrasive was measured by a laser diffraction scattering method using a Microtrac particle size distribution meter "MT3300II" (manufactured by Nikkiso Co., Ltd.) to determine the particle diameter ( _D50 ) at 50% cumulative volume.

(Specific surface area)
The specific surface area of the cerium-based abrasive or mixed rare earth abrasive particles was measured in accordance with "6.2 Fluid method (3.5) One-point method" of JIS R 1626:1996 (Method for measuring the specific surface area of fine ceramic powder by the gas adsorption BET method). Nitrogen was used as the adsorbate gas.

[Evaluation of cerium-based abrasives]
The cerium-based abrasives produced in the above Examples and Comparative Examples were evaluated as follows. The evaluation results are summarized in Table 5 below.

(Dissolved Ion Analysis)
When the cerium-based abrasive was dispersed in water, the amounts of lanthanum, fluorine, and chlorine dissolved in the water were calculated by ICP analysis and IC analysis.
[Preparation of samples for ICP analysis and IC analysis]
A 100 mL polyethylene container was charged with 10 g of the cerium-based abrasive and 40 g of pure water as slurry components, as well as 130 g of zirconia beads with a particle size of 1 mm as beads. Using a ball mill stand, the cerium-based abrasive was pulverized at a container rotation speed of 210 rpm for 30 minutes to obtain a mixed solution.
20 mL of the resulting mixed solution was collected and filtered with a membrane filter "SLHN033NS" (manufactured by Nihon Millipore Co., Ltd.) with an aperture of 0.45 μm, and then further filtered with a membrane filter "VSWP02500" (manufactured by Nihon Millipore Co., Ltd.) with an aperture of 0.025 μm attached to a syringe holder to prepare an analytical sample. Note that the analytical sample was used within 48 hours after preparation, and ICP and IC analyses were performed.

[ICP analysis]
To 10 mL of the obtained analytical sample, 10 mL of an aqueous solution of nitric acid (concentration 70% by mass) and ultrapure water mixed at a volume ratio of 1:1 was added, and then the volume was increased to 100 mL with ultrapure water to prepare an ICP analytical sample. The absorbance of this ICP analytical sample at a wavelength of 333.749 nm was measured using an ICP optical emission spectrometer "iCap7000Duo" (manufactured by Thermo Fisher Scientific Co., Ltd.), and the mass concentration (mg/L) of lanthanum atoms was calculated.

[IC Analysis]
10 mL of the obtained analytical sample was diluted 20 times with ultrapure water to prepare an IC analysis sample. This IC analysis sample was measured using an ion chromatography system "ICS-1600" (manufactured by Thermo Fisher Scientific Co., Ltd.) with an eluent containing sodium carbonate and sodium bicarbonate, and the mass concentrations (mg/L) of fluoride ions and chloride ions were calculated.

(Evaluation of rough skin and dermatitis occurrence)
10g of the cerium-based abrasive obtained in the examples and comparative examples and 40g of pure water were placed in a 100mL polyethylene container, and 130g of zirconia beads with a particle size of 1mm were placed in the container. The cerium-based abrasive was pulverized using a ball mill stand at a container rotation speed of 210 rpm for 30 minutes to obtain a mixed solution with a cerium-based abrasive content of 20% by mass. The occurrence of rough skin and dermatitis was examined using this mixed solution.
Specifically, 0.2 ml of the abrasive slurry was applied to the gauze of a bandage on five subjects, and after thorough application, the test substance was directly applied to the inside of the forearm of each subject, and the condition of the skin surface was observed after 30 minutes. Based on the fact that itching and erythema are observed as the rough skin and dermatitis progress, if no itching or erythema is observed, it is considered as no change, if there is itching, it is considered as slightly worse, if there is slight erythema, it is considered as worse, and if there is clearly erythema, it is considered as clearly worse. Based on this, the condition was scored according to the following rough skin evaluation criteria.
[Criteria for assessing the effect of suppressing rough skin and dermatitis]
0 points: no change 1 point: slight worsening 2 points: worsening 3 points: obvious worsening

(Polishing evaluation)
Using each of the cerium-based abrasives obtained in the above Examples and Comparative Examples, 48 g of the cerium-based abrasive, 272 g of pure water, and a rotor φ8×40 mm were placed in a 500 ml beaker, and the mixture was stirred for 1 hour at 500 rpm using a magnetic stirrer REXIM "RS-1DN" manufactured by AS ONE Corporation, to prepare an abrasive slurry containing 15 mass % of the cerium-based abrasive. Using this abrasive slurry, a sample of alkali-free glass for TFT liquid crystal displays (50 mm×50 mm×thickness 1.1 mm, polishing area 25 ^cm2 ) was polished with a single-sided polisher under the following polishing conditions, and the polishing speed and polishing scratches were evaluated.
[Polishing conditions]
Polishing pad: Suede pad Lower platen rotation speed: 260 rpm
Polishing pressure: 100g/ ^cm2
Polishing time: 20 minutes x 3 sheets

The evaluation methods are as follows:
[Polishing speed]
The thickness of each sample was measured before and after polishing at five points with a micrometer, and the average thickness reduction amount (ΔT [μm]) was calculated. The average value of [ΔT/polishing time (20 minutes)] for three samples was taken as the polishing rate.
[Grinding scratches]
The polished surface of the sample after polishing was observed under a differential interference microscope (Olympus Corporation, "BX51M") at a magnification of 50 times to count the number of scratches, and the average value for three samples was calculated.

As can be seen from Table 5, it was confirmed that the cerium-based abrasives (Examples 1 to 25) in which the amount of lanthanum dissolved in the mixed solution obtained by a predetermined method was 40 mg/L or less suppressed the occurrence of rough skin and dermatitis. It was also confirmed that the polishing solution containing the cerium-based abrasive suppressed the occurrence of polishing scratches and enabled polishing at a good polishing rate.

Claims (10)

A cerium-based abrasive containing mixed rare earth abrasive particles containing lanthanum, cerium and fluorine atoms , and a lanthanum dissolution inhibitor,
The mixed rare earth abrasive particles have a fluorine atom content of 0.1% by mass or more and 10% by mass or less;
The content of cerium in terms of oxide is 55.0 mass% or more and 90.0 mass% or less in terms of oxide, and the content of lanthanum in terms of oxide is 1.0 mass% or more and 45.0 mass% or less in terms of oxide, in the total content of rare earth elements in terms of oxide (TREO),
The particle size ( _D50 ) is 0.10 μm or more and 10.0 μm or less,
The specific surface area is 1.0 m ² /g or more and 10.0 m ² /g or less,
the lanthanum dissolution inhibitor is at least one selected from the group consisting of an alkali metal carbonate, an alkaline earth metal carbonate, an alkaline earth metal phosphate, and an alkaline earth metal organic acid salt ;
The content of the lanthanum dissolution inhibitor is 0.01 parts by mass or more and 1.00 parts by mass or less per 100 parts by mass of the mixed rare earth abrasive particles,
A 100 mL polyethylene container is charged with 10 g of the cerium-based abrasive, 40 g of pure water, and 130 g of zirconia beads having a particle size of 1 mm. The cerium-based abrasive is pulverized using a ball mill stand at a container rotation speed of 210 rpm for 30 minutes to obtain a mixed liquid having a dissolved amount of lanthanum of 40 mg/L or less. a first agent containing the mixed rare earth abrasive particles;
A second agent containing a lanthanum dissolution inhibitor;
2. The cerium-based abrasive according to claim 1, which is a two-component type comprising: The cerium-based abrasive according to claim 1, containing 0.1 to 10 mass% of fluorine atoms. 4. The cerium-based abrasive according to claim 1 , wherein the molecular weight of the lanthanum dissolution inhibitor is 300 or less. 4. The cerium-based abrasive according to claim 1, wherein the lanthanum dissolution inhibitor is contained in an amount of 0.01 to 0.9 parts by mass per 100 parts by mass of the mixed rare earth abrasive particles. A polishing solution containing the cerium-based abrasive according to claim 1 and at least one selected from water and a water-soluble organic solvent. A method for producing the polishing liquid according to claim 6 , comprising the steps of:
The cerium-based abrasive;
one or more selected from the group consisting of water and the water-soluble organic solvent;
and (I) mixing the above to form a slurry. A method for producing the polishing liquid according to claim 6 , comprising the steps of:
The cerium-based abrasive;
The lanthanum dissolution inhibitor;
one or more selected from the group consisting of water and the water-soluble organic solvent;
and (II) mixing the above to form a slurry. A method for producing the polishing liquid according to claim 6 , comprising the steps of:
The cerium-based abrasive;
one or more selected from the group consisting of water and the water-soluble organic solvent;
(III) mixing the above to form a slurry;
The slurry obtained in the step (III) is
A method for producing a polishing liquid, comprising: a step (IV) of adding and mixing the lanthanum dissolution inhibitor. A method for polishing glass, comprising the step of carrying out polishing using the polishing liquid according to claim 6 .