Classifications

• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K3/00—Materials not provided for elsewhere
  • C09K3/14—Anti-slip materials; Abrasives
  • C09K3/1409—Abrasive particles per se
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
  • C01F17/00—Compounds of rare earth metals
  • C01F17/20—Compounds containing only rare earth metals as the metal element
  • C01F17/206—Compounds containing only rare earth metals as the metal element oxide or hydroxide being the only anion
  • C01F17/241—Compounds containing only rare earth metals as the metal element oxide or hydroxide being the only anion containing two or more rare earth metals, e.g. NdPrO3 or LaNdPrO3
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09G—POLISHING COMPOSITIONS; SKI WAXES
  • C09G1/00—Polishing compositions
  • C09G1/02—Polishing compositions containing abrasives or grinding agents
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K3/00—Materials not provided for elsewhere
  • C09K3/14—Anti-slip materials; Abrasives

Definitions

• the present invention provides a cerium-based abrasive material, a polishing liquid, and a method for producing a polishing liquid used for polishing glass materials such as glass substrates used for liquid crystal panels, hard disks, specific frequency cut filters, glass substrates for optical lenses, etc. , and a glass polishing method.
• Glass materials are used for various purposes, and depending on the purpose, surface polishing may be required.
• glass materials such as glass substrates used in liquid crystal panels, hard disks, specific frequency cut filters, glass substrates for optical lenses, etc. are required to be polished with high smoothness and high efficiency.
• cerium-based abrasives such as those described in Patent Document 1 and Patent Document 2, are often used, for example.
• Cerium-based abrasives are generally used as glass abrasives, and those containing lanthanum are often used. Cerium-based abrasives are generally used in the form of a slurry dispersed in water. The slurry is neutral to alkaline and may irritate the skin of some users, causing symptoms such as rough skin and dermatitis. Therefore, there has been a need for a cerium-based abrasive material that has less skin irritation and is easier to handle.
• the present invention has been made to solve the above-mentioned problems, and provides a cerium-based abrasive material, a polishing liquid, a method for producing a polishing liquid, and a glass polishing method that suppress the occurrence of rough skin and dermatitis.
• the task is to do so.
• the present invention provides a cerium abrasive material containing mixed rare earth abrasive particles containing lanthanum and cerium, in which the content of cerium in terms of oxide in the total content of rare earth elements in terms of oxide (TREO) is 55.0% by mass.
• the dissolved amount of lanthanum in the mixed liquid containing the cerium-based abrasive and obtained by a predetermined method is 40 mg/L or less, rough skin and dermatitis that occur when it adheres to the skin can be prevented. Based on the discovery that it can be reduced.
• 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 oxide equivalent content of the cerium in the total rare earth element oxide equivalent content (TREO) is 55.0% by mass or more,
• a 100 mL polyethylene container put 10 g of the cerium-based abrasive material and 40 g of pure water as well as 130 g of zirconia beads with a particle size of 1 mm as beads, and use a ball mill stand to perform the cerium-based polishing at the container rotation speed of 210 rpm for 30 minutes.
• a cerium-based abrasive material in which the amount of lanthanum dissolved in a liquid mixture obtained by pulverizing the material is 40 mg/L or less.
• the cerium-based abrasive material according to [1] above further containing a lanthanum dissolution inhibitor.
• the cerium-based abrasive material according to the above [1] which is a two-part type containing.
• the lanthanum dissolution inhibitor is an alkali metal carbonate, an alkali metal phosphate, an alkali metal hydroxide salt, an alkali metal sulfate, an alkali metal nitrate, an alkali metal organic acid salt, an alkali Earth metal carbonates, alkaline earth metal phosphates, alkaline earth metal hydroxide salts, alkaline earth metal sulfates, alkaline earth metal nitrates, alkaline earth metal organic acid salts, [2] or [3] above, which is one or more selected from ammonium carbonate, ammonium phosphate, ammonium hydroxide salt, ammonium sulfate, ammonium nitrate, and ammonium organic acid salt.
• the lanthanum dissolution inhibitor is one or more selected from alkaline earth metal carbonates, alkaline earth metal phosphates, alkaline earth metal organic acid salts, and alkali metal carbonates. , the cerium-based abrasive material according to [6] above. [8] The cerium-based abrasive material according to [2] or [3] above, wherein the lanthanum dissolution inhibitor has a molecular weight of 300 or less.
• the cerium-based abrasive material according to [2] or [3] above which contains 0.001 to 0.9 parts by mass of the lanthanum dissolution inhibitor based on 100 parts by mass of the mixed rare earth abrasive particles.
• the present invention it is possible to provide a cerium-based abrasive material, a polishing liquid, a method for producing a polishing liquid, and a glass polishing method in which the occurrence of rough skin and dermatitis is suppressed.
• volume-based cumulative particle size distribution refers to volume-based cumulative particle size distribution determined from particle size distribution measured by laser diffraction/scattering method. This is the particle size that is 50% of the total. Specifically, it is a value measured using a Microtrac particle size distribution analyzer described in the Examples below.
• the cerium-based abrasive of the present embodiment is a cerium-based abrasive containing mixed rare earth abrasive particles containing lanthanum and cerium, and has a total rare earth element oxide equivalent content (TREO; an abbreviation for Total Rare Earth Oxides).
• the content of cerium in terms of oxide (CeO 2 ) (hereinafter referred to as "amount of CeO 2 /TREO") is 55.0% by mass or more.
• the TREO in the cerium-based abrasive of this embodiment is derived from mixed rare earth abrasive particles.
• the TREO in the mixed rare earth abrasive particles is preferably 85.0% by mass or more, more preferably 90.0% by mass or more, even more preferably 92.0% by mass or more, from the viewpoint of improving the polishing rate.
• the content is preferably 95.0% by mass or less.
• the cerium oxide (CeO 2 ) equivalent content (CeO 2 amount/TREO) in TREO is 55.0% by mass or more, and from the viewpoint of improving the polishing rate, preferably 60.0% by mass or more, more Preferably it is 62.0% by mass or more, more preferably 64.0% by mass or more.
• the amount of CeO2 /TREO is preferably 90.0% by mass or less, more preferably 80.0% by mass. % or less, more preferably 75.0% by mass or less, even more preferably 70.0% by mass or less.
• La 2 O 3 amount/TREO The lanthanum oxide (La 2 O 3 ) equivalent content (hereinafter referred to as La 2 O 3 amount/TREO) in TREO is preferably 0.00 to suppress the occurrence of scratches on the polished surface. 01% by mass or more, more preferably 1.0% by mass or more, still more preferably 10.0% by mass or more, even more preferably 20.0% by mass or more, even more preferably 30.0% by mass or more.
• the amount of La 2 O 3 /TREO is 45.0% by mass or less since the amount of Ce in TREO is 55.0% by mass or more, from the viewpoint of improving the polishing rate and from the viewpoint of reducing rough skin and dermatitis. , preferably 40.0% by mass or less, more preferably 37.0% by mass or less, even more preferably 35.0% by mass or less.
• TREO can be measured by oxalate precipitation, calcination, and gravimetric methods, and specifically, it can be measured by the method described in the Examples below.
• the content of each rare earth element such as Ce and La can be measured by instrumental analysis such as high-frequency inductively coupled plasma (ICP) analysis or fluorescent X-ray analysis.
• ICP inductively coupled plasma
• fluorescent X-ray analysis The value obtained by converting each rare earth element as an oxide from the measured value by -AES) is defined as the oxide equivalent amount.
• cerium-based abrasive material of this embodiment can suppress rough skin and dermatitis.
• the lanthanum contained in the cerium-based abrasive is eluted and dissolved in water, water-soluble organic solvents, etc. as lanthanum ions when the cerium-based abrasive is manufactured or made into a slurry. If a large amount of lanthanum is dissolved in the liquid, it will combine with chloride ions derived from the raw material of the cerium-based abrasive to produce highly toxic lanthanum chloride, which will adhere to human skin and cause rough skin and dermatitis.
• the amount of lanthanum dissolved in the liquid mixture obtained by the above prescribed method is 40 mg/L or less, and from the viewpoint of further suppressing the occurrence of rough skin and dermatitis, it is preferably 35 mg/L or less, more preferably 30 mg/L. Below, it is more preferably 25 mg/L or less, and from the viewpoint of cost, preferably 0.1 mg/L or more, more preferably 0.5 mg/L or more, and still more preferably 1.0 mg/L or more.
• the ratio of the cerium-based abrasive material, water as a dispersion medium, and water-soluble organic solvent in the slurry is determined according to the above-described method. Although it may differ from the above, the effect of the present embodiment is exhibited as long as the dissolved lanthanum concentration is equal to or lower than that measured by the measurement method.
• the amount of lanthanum dissolved is a value calculated from ICP analysis, and specifically, a value calculated by the method described in the following example.
• chloride ions derived from the raw materials of the cerium-based abrasives are dissolved in water, water-soluble organic solvents, etc. along with lanthanum ions.
• the amount of chlorine dissolved in the mixed liquid obtained by the above-described method is preferably 40 mg/L or less, more preferably 35 mg/L or less, still more preferably 25 mg/L, from the viewpoint of further suppressing the occurrence of rough skin and dermatitis. From the viewpoint of cost, it is preferably 0.1 mg/L or more, more preferably 0.5 mg/L or more, and still more preferably 1.0 mg/L or more.
• the "chlorine dissolution amount" is a value calculated from IC analysis, specifically, a value calculated by the method described in the following example.
• the particle size (D 50 ) of the cerium-based abrasive of this embodiment is preferably 0.10 ⁇ m or more, more preferably 0.3 ⁇ m or more, and even more preferably D50 is preferably 0.5 ⁇ m or more, more preferably 0.7 ⁇ m or more, 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 ⁇ m or less, more preferably Preferably it is 5.0 ⁇ m or less, more preferably 3.0 ⁇ m or less.
• the specific surface area of the cerium-based abrasive material of this embodiment is preferably 1.0 m 2 /g or more, more preferably 2.0 m 2 /g or more, from the viewpoint of suppressing the occurrence of scratches on the polished surface. It is preferably 3.0 m 2 /g or more, and from the viewpoint of improving the polishing rate, it is preferably 10.0 m 2 /g or less, more preferably 8.0 m 2 /g or less, and even more preferably 7.0 m 2 /g or less. , even more preferably 6.0 m 2 /g or less. Note that in this specification, the specific surface area is a value measured by the BET method (single point method).
• the cerium-based abrasive material of this embodiment may contain fluorine atoms from the viewpoint of improving the polishing rate.
• the fluorine atom content in the cerium-based abrasive is preferably 0.1% by mass or more, more preferably 1.0% by mass or more, and It is preferably 3.0% by mass or more, and from the viewpoint of suppressing the occurrence of scratches on the polished surface, preferably 10.0% by mass or less, more preferably 9.0% by mass or less, and even more preferably 8.0% by mass.
• the content is more preferably 7.0% by mass or less.
• the fluorine atom content in a cerium-based abrasive can be measured by melting the cerium-based abrasive into an aqueous solution using an ion electrode method.
• TREO in the cerium-based abrasive material of this embodiment 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. , preferably 99.0% by mass or less, from the viewpoint of further improving the polishing rate by containing elements other than the elements constituting TREO, and from the viewpoint of suppressing the occurrence of surface defects (fine surface irregularities) on the polished surface. , more preferably 97.0% by mass or less, still more preferably 96.0% by mass or less.
• the mixed rare earth abrasive particles may contain rare earth elements other than Ce and La (lanthanum). Examples of the rare earth elements include Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, and Yb.
• the particle size (D 50 ) of the mixed rare earth abrasive particles of this embodiment is preferably 0.10 ⁇ m or more, more preferably 0.3 ⁇ m or more, and even more preferably is 0.5 ⁇ m or more, more preferably 0.7 ⁇ m or more, and is preferably 10.0 ⁇ m or less, more preferably It is 5.0 ⁇ m or less, more preferably 3.0 ⁇ m or less.
• 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, from the viewpoint of suppressing the occurrence of scratches on the polished surface. More preferably, it is 3.0 m 2 /g or more, and from the viewpoint of improving the polishing rate, it is preferably 10.0 m 2 /g or less, more preferably 8.0 m 2 /g or less, and even more preferably 7.0 m 2 /g. Below, it is still more preferably 6.0 m 2 /g or less. Note that 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.
• the fluorine atom content in the mixed rare earth abrasive particles is preferably 0.1% by mass or more, more preferably 1.0% by mass or more, from the viewpoint of improving the polishing rate. , more preferably 3.0% by mass or more, and from the viewpoint of suppressing the occurrence of scratches on the polished surface, preferably 10.0% by mass or less, more preferably 9.0% by mass or less, even more preferably 8.0% by mass. It is not more than 7.0% by mass, more preferably not more than 7.0% by mass.
• the cerium-based abrasive of this embodiment may contain, in addition to the mixed rare earth abrasive particles, a lanthanum dissolution inhibitor that suppresses dissolution of lanthanum.
• Lanthanum dissolution inhibitors include those that have the effect of converting lanthanum ions dissolved in water or water-soluble organic solvents into insoluble salts, etc. and precipitate them, and those that have the effect of fixing lanthanum ions through chelating action. Preferably.
• Such lanthanum dissolution inhibitors include alkali metal carbonates, alkali metal phosphates, alkali metal hydroxides, alkali metal sulfates, alkali metal nitrates, alkali metal organic acid salts, alkali Earth metal carbonates, alkaline earth metal phosphates, alkaline earth metal hydroxide salts, alkaline earth metal sulfates, alkaline earth metal nitrates, alkaline earth metal organic acid salts, Preferably, it is one or more selected from ammonium carbonate, ammonium phosphate, ammonium hydroxide salt, ammonium sulfate, ammonium nitrate, and ammonium organic acid salt, and the resulting salt is safe. From the viewpoint of properties, it is more preferable that the carbonate is one or more selected from alkaline earth metal carbonates, alkaline earth metal phosphates, alkaline earth metal organic acid salts, and alkali metal carbonates.
• the alkali metal sodium and potassium are preferred, and sodium is more preferred, from the viewpoint of safety of the generated salt.
• calcium and magnesium are preferred as the alkaline earth metals.
• the lanthanum dissolution inhibitors include monocalcium phosphate, dibasic calcium phosphate, calcium hydroxide, calcium carbonate, calcium gluconate, calcium citrate, sodium bicarbonate, ammonium bicarbonate, dibasic magnesium phosphate, dibasic Calcium phosphate and the like are preferred, and among these, dibasic calcium phosphate is more preferred from the viewpoint of further suppressing the occurrence of rough skin and dermatitis, ensuring the safety of the produced salt, and suppressing the occurrence of scratches on the polished surface.
• the lanthanum dissolution inhibitors may be used alone or in combination of two or more.
• 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 preferably 300 or less, more preferably It is 200 or less, more preferably 150 or less.
• a molecular weight of 300 or less is preferable because it has high reactivity with lanthanum ions and a high lanthanum dissolution suppressing effect.
• the cerium-based abrasive of this embodiment contains a lanthanum dissolution inhibitor
• the cerium-based abrasive may be a one-component type containing the lanthanum dissolution inhibitor in advance, and the mixed rare earth abrasive particles It may be a two-dose type containing a first part containing a lanthanum dissolution inhibitor and a second part containing a lanthanum dissolution inhibitor.
• the content of the mixed rare earth abrasive particles is preferably 85.0% by mass or more, more preferably 90.0% by mass or more, even more preferably 92.0% by mass or more, from the viewpoint of improving the polishing rate, and prevents rough skin and From the viewpoint of suppressing the occurrence of dermatitis, the content is preferably 99.9% by mass or less, more preferably 99.5% by mass or less, even more preferably 99.2% by mass or less.
• the content of the lanthanum dissolution inhibitor in the cerium-based abrasive is preferably 0.95 parts by mass per 100 parts by mass of mixed rare earth abrasive particles in both one-part and two-part types. It is not more than 0.85 parts by mass, more preferably not more than 0.75 parts by mass. Further, from the viewpoint of suppressing the occurrence of rough skin and dermatitis, the amount 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.
• 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, in both one-part and two-part types. It is not more than 0.80% by mass, more preferably not more than 0.70% by mass, even more preferably not more than 0.70% by mass.
• 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, in both one-part and two-part types. It is not more than 0.80% by mass, more preferably not more than 0.70% by mass, even more preferably not more than 0.70% by mass.
• the cerium-based abrasive material of this embodiment contains additives such as glycols such as ethylene glycol and polyethylene glycol, polyacrylate, etc., in order to improve dispersibility, prevent sedimentation, prevent solidification, improve stability, and improve workability. Even if sodium salts of acids, polymeric dispersants such as polycarboxylic acid polymers and polysulfonic acid polymers, cellulose ethers such as methylcellulose and carboxymethylcellulose, water-soluble polymers such as polyvinyl alcohol, and phosphoric acid compounds are added. good. These may be used alone or in combination of two or more.
• polymer dispersants When adding additives, among these, polymer dispersants, phosphoric acid compounds, and cellulose ethers are preferred from the viewpoint of further improving dispersibility, preventing sedimentation, preventing solidification, improving stability, and improving workability.
• polymeric dispersants include poly(meth)acrylic acid, polyhydroxy(meth)acrylic acid, (meth)acrylic acid copolymers such as copolymers of (meth)acrylic acid and maleic acid, and copolymers of olefin and maleic acid.
• Examples include copolymers, copolymers of maleic acid and allyl alcohol with alkylene oxide adducts such as ethylene oxide and propylene oxide, copolymers of allylsulfonic acid and maleic acid, and alkali metal salts thereof such as sodium salts and potassium salts. It will be done. Among these, polyacrylic acid, a copolymer of acrylic acid and maleic acid, or an alkali metal salt thereof is preferable, a copolymer of acrylic acid and maleic acid or an alkali metal salt thereof is more preferable, and a copolymer of acrylic acid and maleic acid or an alkali metal salt thereof is more preferable. Even more preferred is the sodium salt of a copolymer of .
• Examples of phosphoric acid compounds include inorganic phosphoric acids such as tripolyphosphoric acid, pyrophosphoric acid, tetrametaphosphoric acid, hexametaphosphoric acid, orthophosphoric acid, and phosphorous acid; aminotrimethylenephosphonic acid, and 1-hydroxyethylidene-1,1-diphosphonic acid. , organic phosphonic acids such as ethylenediaminetetramethylenephosphonic acid and diethylenetriaminepentamethylenephosphonic acid; or alkali metal salts thereof such as sodium salts and potassium salts. Among these, tripolyphosphoric acid, pyrophosphoric acid, hexametaphosphoric acid, or alkali metal salts thereof are preferred, and sodium tripolyphosphate is more preferred.
• inorganic phosphoric acids such as tripolyphosphoric acid, pyrophosphoric acid, tetrametaphosphoric acid, hexametaphosphoric acid, orthophosphoric acid, and phosphorous acid
• the content of the additive relative to 100 parts by mass of the mixed rare earth abrasive particles is preferably from the viewpoint of improving dispersibility, preventing sedimentation, preventing solidification, improving stability, and improving workability.
• the amount is 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, even more preferably 0.5 parts by mass or more, and from the viewpoint of cost, preferably 10.0 parts by mass or more. It is not more than 5.0 parts by mass, more preferably not more than 3.0 parts by mass.
• the content of the additive in the cerium-based abrasive is preferably 0 from the viewpoint of improving dispersibility, preventing sedimentation, preventing solidification, improving stability, and improving workability. .01% by mass or more, more preferably 0.1% by mass or more, even more preferably 0.3% by mass or more, even more preferably 0.5% by mass or more, and from the viewpoint of cost, preferably 10.0% by mass. % or less, more preferably 5.0% by mass or less, still more preferably 3.0% by mass or less.
• the method for producing the cerium-based abrasive is not particularly limited, but specifically includes the step (1) of preparing a mixed light rare earth compound, and the production of a mixed rare earth oxide raw material from the mixed light rare earth compound.
• a cerium-based abrasive is produced through step (2) of wet-pulverizing the mixed rare earth oxide raw material, followed by firing, crushing, and classification to obtain mixed rare earth abrasive particles. It is preferable to do so.
• a step (4) of further adding and mixing a lanthanum dissolution inhibitor after the step (3), or preparing a second agent containing a lanthanum dissolution inhibitor (4) ) It is more preferable to produce a cerium-based abrasive. "Mixing” here is also synonymous with “mixing” of the mixed rare earth abrasive particles described above. Each step will be explained in order below.
• 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 impurity components other than rare earth elements and medium and heavy rare earths from an ore containing rare earth elements by chemical treatment.
• the mixed light rare earth compound is preferably one in which the content of impurity components such as alkali metals, alkaline earth metals, and non-rare earth components such as radioactive substances, as well as the content of medium and heavy rare earths is reduced.
• medium-heavy rare earth refers to a rare earth element having an atomic number larger than Pm
• rare earth elements other than medium-heavy rare earth are referred to as light rare earth.
• the ore containing rare earth elements for example, rare earth concentrate obtained from raw material ores such as natural monazite and bastnasite, which contain a large amount of Ce, are preferably used.
• sulfuric acid roasting is a common chemical treatment method for reducing the content of impurity components.
• the pulverized raw material ore is roasted with sulfuric acid to produce sulfate (rare earth sulfate), and this sulfate is dissolved in water to form a rare earth sulfate solution, which removes impurity components that are insoluble matter.
• This method removes the substances by filtration or the like.
• the content of impurity components in the mixed light rare earth compound is preferably reduced to 1.0% by mass or less.
• a chemical treatment method for reducing the content of medium and heavy rare earth for example, carbonate is added to the sulfuric acid rare earth solution after the sulfuric acid roasting to obtain crude rare earth carbonate, and then hydrochloric acid is added to this.
• it can be carried out by preparing a mixed rare earth chloride aqueous solution and performing solvent extraction using an organic solvent.
• 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 and using additives.
• the content of medium and heavy rare earths in the mixed light rare earth compound is preferably reduced to 1.0% by mass or less.
• 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 is obtained by, for example, producing mixed rare earth carbonate, which is a carbonate, using a mixed light rare earth compound, sodium carbonate, ammonium bicarbonate, etc., and then firing the mixed rare earth carbonate. .
• the firing temperature when firing the mixed rare earth carbonate to obtain the mixed rare earth oxide raw material is adjusted appropriately depending on the composition of the mixed rare earth carbonate, but is preferably 500 to 1200°C, more preferably 600°C. ⁇ 1100°C, more preferably 700 ⁇ 1000°C.
• the firing time is preferably 0.5 to 48 hours, more preferably 1 to 40 hours, and still more preferably 1.5 to 30 hours.
• the firing atmosphere is preferably an air atmosphere. After firing, the mixed rare earth oxide raw material may be crushed by a mechanical method to adjust it to particles having a desired particle size.
• the mixed rare earth oxide raw material is also commercially available, and commercially available products may be used.
• Mixed rare earth oxide raw materials can be obtained by firing mixed light rare earth compounds such as mixed rare earth carbonate, mixed monooxy rare earth carbonate, mixed rare earth oxalate, and mixed rare earth hydroxide, and are therefore commercially available.
• mixed rare earth oxide raw material of the product mixed rare earth carbonate, mixed rare earth monooxycarbonate, mixed rare earth oxalate, etc., which are the manufacturing raw materials, may remain in the mixed rare earth oxide raw material of the product.
• step (3) the mixed rare earth oxide raw material is wet-pulverized, then fired, crushed, and classified to obtain mixed rare earth abrasive particles.
• Wet pulverization is preferably carried out using a media mill such as a wet ball mill from the viewpoint of obtaining homogeneous mixed rare earth abrasive particles.
• a media mill such as a wet ball mill from the viewpoint of obtaining homogeneous mixed rare earth abrasive particles.
• water, water-soluble organic solvents, etc. are preferably used.
• mixed rare earth abrasive particles are obtained by drying, firing, crushing, and classifying. Drying, calcination, crushing and classification can be carried out in a manner similar to that applied in the production of conventional mixed rare earth abrasive particles.
• the firing temperature is preferably 600 to 1200°C, more preferably 650 to 1150°C, and still more preferably 700 to 1100°C.
• the firing time at the target 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.
• mixed rare earth abrasive particles may contain fluorine atoms.
• the method of incorporating fluorine atoms is not particularly limited, but the mixed fluorinated rare earth raw material is mixed with the mixed rare earth oxide raw material, wet-pulverized, calcined, crushed and classified, and then mixed. Preferred are methods for obtaining rare earth abrasive particles.
• the method for obtaining the mixed rare earth fluoride raw material is not particularly limited, but for example, a fluoride such as hydrofluoric acid, ammonium fluoride, or acidic ammonium fluoride is added to the mixed light rare earth compound as a fluorine source. It can be obtained by heat treatment.
• the temperature of the heat treatment is preferably 400° C. or lower from the viewpoint of obtaining a cerium-based abrasive that is homogeneous and has excellent polishing properties.
• the heat treatment atmosphere is preferably in the air.
• the heat treatment time is preferably 0.1 to 10 hours, more preferably 0.5 to 5 hours, and still more preferably 1.0 to 4 hours.
• the firing atmosphere is preferably an air atmosphere.
• a method of obtaining mixed rare earth abrasive particles by mixing a mixed fluorinated rare earth raw material with a mixed rare earth oxide raw material is to add fluorides such as ammonium fluoride or hydrofluoric acid directly to the mixed rare earth oxide raw material to obtain mixed rare earth polishing.
• This method is safer and lower cost than the method of obtaining raw material particles, and can easily obtain mixed rare earth abrasive particles containing fluorine.
• 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. Further, it is preferable that the mixed rare earth fluoride raw material contains cerium as a main component among all rare earth elements contained.
• the cerium oxide equivalent content ( CeO2 amount/TREO) in TREO is preferably 55.0% by mass or more, more preferably 60.0% by mass or more from the viewpoint of improving the polishing rate, and further Preferably it is 62.0% by mass or more, and even more preferably 64.0% by mass or more.
• the amount of CeO2 /TREO is preferably 90.0% by mass or less, more preferably 80.0% by mass. % or less, more preferably 75.0% by mass or less, even more preferably 70.0% by mass or less.
• the fluorine atom content in the mixed rare earth fluoride raw material is preferably 10 to 30% by mass, more preferably 15 to 30% by mass, and still more preferably 20 to 30% by mass.
• the amount of the mixed rare earth fluoride raw material added to the mixed rare earth oxide raw material is appropriately determined depending on 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 is added in an amount of 1 to 40% by mass relative to the total of 100% by mass of the mixed rare earth oxide raw material and the mixed rare earth fluoride raw material. The amount is preferably 3 to 35% by weight, and even more preferably 5 to 30% by weight.
• Step (4) is, after step (3), adding and mixing a lanthanum dissolution inhibitor to the mixed rare earth abrasive particles obtained in step (3), or preparing a second agent containing a lanthanum dissolution inhibitor.
• the cerium-based abrasive is a one-component type
• the mixed rare earth abrasive particles may be directly used as the cerium-based abrasive without going through step (4), or the mixed rare earth abrasive particles obtained in step (3) may be used as the cerium-based abrasive.
• a cerium-based abrasive may be obtained by adding and mixing a lanthanum dissolution inhibitor to rare earth abrasive particles.
• additives may be added and mixed together with the lanthanum dissolution inhibitor.
• the mixing method is not particularly limited, and for example, the mixture may be mixed using a stirrer such as a batch type stirrer, or may be mixed using a medium mill such as a ball mill or a bead mill.
• a stirrer such as a batch type stirrer
• a medium mill such as a ball mill or a bead mill.
• a second part containing a lanthanum dissolution inhibitor is prepared in step (4).
• the cerium-based abrasive is a two-part type containing a first part containing the mixed rare earth abrasive particles and a second part containing a lanthanum dissolution inhibitor
• the mixed rare earth abrasive A first part containing particles and a second part containing a lanthanum dissolution inhibitor may be prepared separately, and the first part and second part may be mixed at the time of manufacturing the polishing liquid.
• the second agent may or may not contain water, a water-soluble organic solvent, additives, etc. in addition to the lanthanum dissolution inhibitor.
• 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 contain components other than a cerium-based abrasive, one or more selected from water and a water-soluble organic solvent, and a lanthanum dissolution inhibitor.
• the polishing liquid of this embodiment is a polishing liquid that suppresses skin roughness, dermatitis, etc. caused by adhesion to human skin.
• the polishing liquid is used in such a manner that the content of the cerium-based abrasive in the polishing liquid is in the range of 0.1 to 40.0% by mass from the viewpoint of exhibiting good polishing performance and from the viewpoint of cost. It is preferably from 1.0 to 35.0% by weight, even more preferably from 3.0 to 30.0% by weight, even more preferably from 5.0 to 20.0% by weight.
• the polishing liquid may be added with, for example, a pH adjuster or an antifoaming agent, if necessary, within a range that does not impede the polishing performance, when preparing the polishing liquid, taking into account the polishing target and the specifications of the polishing apparatus. , an additive such as a rust preventive agent may be added.
• the polishing liquid is particularly suitable for final polishing of various glass materials and glass products, such as glass substrates for optical disks and magnetic disks, glass substrates for liquid crystal displays, glass substrates for color filters and photomasks, and glass substrates for optical lenses. It is suitably used for.
• 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 one or more selected from water and a water-soluble organic solvent.
• the method for producing a polishing liquid includes a step (I) of mixing the cerium-based abrasive and one or more selected from the water and the water-soluble organic solvent to form a slurry.
• the cerium-based abrasive may or may not contain the lanthanum dissolution inhibitor.
• the cerium-based abrasive is a two-part type containing a first part containing mixed rare earth abrasive particles and a second part containing a lanthanum dissolution inhibitor
• the cerium-based abrasive is Step (I) is performed using the first agent and the second agent.
• the method of making the slurry is not particularly limited, but for example, it may be made into a slurry by mixing with a stirrer, or it may be made using a grinder such as a wet ball mill, an attritor, or a bead mill. It may also be made into a slurry.
• the method for producing a polishing liquid comprises mixing the cerium-based abrasive, the lanthanum dissolution inhibitor, and one or more selected from the water and the water-soluble organic solvent to form a slurry.
• the cerium-based abrasive may or may not contain the lanthanum dissolution inhibitor.
• the method of making a slurry in step (II) is the same as the method of making a slurry in step (I).
• the method for producing a polishing liquid includes a step (III) of mixing the cerium-based polishing material and one or more selected from the 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 of making a slurry in step (III) is the same as the method of making a slurry in step (I).
• the glass polishing method of the present invention is a method of polishing using the above polishing liquid.
• the glass polishing method is not particularly limited other than using the polishing liquid, and a method using a known polishing device or the like can be applied.
• the polishing liquid can be used in a known manner when performing final polishing such as mirror polishing of a glass material using, for example, a single-sided polisher or a double-sided polisher.
• TREO in the preparation of the mixed rare earth oxide raw material, the preparation of the mixed fluoride rare earth raw material, Examples, and Comparative Examples, the oxide equivalent content of each rare earth element in TREO ( CeO2 amount/TREO, La2O
• the fluorine atom content was determined as follows. [TREO] Aqueous ammonia was added to a solution in which the measurement sample was dissolved in acid. The generated precipitate was filtered and washed to remove alkali metals, and then dissolved in acid again. Oxalic acid was added to this solution, and the resulting precipitate was calcined in the air at 800° C.
• the TREO of the mixed rare earth abrasive particles is obtained from "the total amount of rare earth oxide obtained after firing/the mass of the mixed rare earth abrasive particles before acid dissolution treatment", and the TREO of the cerium abrasive is obtained from "the total amount of rare earth oxide obtained after firing/the mass of the mixed rare earth abrasive particles before acid dissolution treatment”. It is obtained from the formula: total amount of rare earth oxide substances/mass of cerium abrasive material before acid dissolution treatment.
• This mixed light rare earth compound has a cerium oxide equivalent ([CeO 2 ]) content (CeO 2 amount/TREO) of 64.7% by mass in TREO and a lanthanum oxide equivalent ([La 2 O 3 ] ) content (La 2 O 3 amount/TREO) is 34.1% by mass, neodymium oxide equivalent ([Nd 2 O 3 ]) content (Nd 2 O 3 amount/TREO) is 0.6% by mass, The praseodymium oxide equivalent ([Pr 6 O 11 ]) content (Pr 6 O 11 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.
• the mixed rare earth carbonate had a TREO content of 49% by mass.
• This mixed rare earth carbonate was heat treated at 800° C. for 10 hours in the atmosphere in a firing furnace to obtain a mixed rare earth oxide raw material A.
• Table 1 shows the TREO, amount of CeO 2 /TREO, amount of La 2 O 3 /TREO, amount of Nd 2 O 3 /TREO, and amount of Pr 6 O 11 /TREO of mixed rare earth oxide raw material A.
• mixed rare earth oxide raw materials B to E In the same way as in the preparation of mixed rare earth oxide raw material A, mixed rare earth oxide raw materials B to E were prepared by using a mixed light rare earth compound and adjusting the treatment conditions thereof and the heat treatment conditions of mixed rare earth carbonate. .
• Table 1 shows the TREO, CeO 2 amount/TREO, La 2 O 3 amount/TREO, Nd 2 O 3 amount/TREO, and Pr 6 O 11 amount/TREO of the mixed rare earth oxide raw materials B to E.
• mixed rare earth fluoride raw materials G to I Similarly to the preparation of mixed rare earth fluoride raw material F, mixed rare earth fluoride raw materials G to I were each prepared by adjusting the treatment conditions using a mixed light rare earth compound. Table 2 shows the TREO, CeO 2 amount/TREO, and fluorine content of the mixed rare earth fluoride raw materials G to I.
• Cerium-based abrasives were manufactured according to the following Examples and Comparative Examples. Details of the additives used in the following Examples and Comparative Examples are shown below.
• ⁇ Additive 1 Sodium tripolyphosphate (Kanto Kagaku Co., Ltd.): Molecular weight over 300
• ⁇ Additive 2 Sodium salt of polyacrylic acid "Poise 530" (Kao Corporation): Molecular weight over 300
• ⁇ Additive 3 Acrylic acid and Maleic acid copolymer sodium salt “Poise 521” (Kao Corporation): Molecular weight over 300
• ⁇ Additive 4 Carboxymethylcellulose (Kanto Kagaku Co., Ltd.): Molecular weight over 300 ⁇ Additive 5: Crystalline cellulose “Cellulose microcrystals” (Kanto Kagaku Co., Ltd.): Molecular weight over 300
• Example 1 After stirring and mixing 1,000 kg of water and a total of 1,400 kg of the mixed rare earth oxide raw material A and the mixed rare earth fluoride raw material F (mass ratio 76:24) in a slurry tank, a wet ball mill (media: 5 mm diameter zirconia A uniform mixed solution was obtained by mixing and pulverizing for 17 hours using a ball. This mixed solution was put into a rotary kiln, dried in the atmosphere at 700°C for 1 hour, and then fired at 960°C for 4 hours. The obtained fired body was left to cool, then crushed and classified to obtain mixed rare earth abrasive particles.
• a cerium-based abrasive was produced by adding dibasic calcium phosphate as a lanthanum dissolution inhibitor to the mixed rare earth abrasive particles in an amount of 0.1 part by mass per 100 parts by mass of the mixed rare earth abrasive particles and mixing with a stirrer. .
• Examples 2 to 25 and Comparative Examples 1 to 5 In the same manner as in Example 1, except that the mixed rare earth oxide raw material, mixed rare earth fluoride raw material, firing temperature, lanthanum dissolution inhibitor, and additives 1 to 5 were as shown in Tables 3 and 4, A cerium-based abrasive was manufactured.
• Particle size distribution D50 Disperse cerium-based abrasive or mixed rare earth abrasive particles in pure water containing a dispersant, prepare a measurement sample, and use a Microtrac particle size distribution meter "MT3300II" (manufactured by Nikkiso Co., Ltd.) by laser diffraction scattering method. The particle size distribution of the cerium-based abrasive was measured, and the particle diameter (D 50 ) at a cumulative volume of 50% was determined.
• MT3300II Microtrac particle size distribution meter
• ICP analysis After adding 10 mL of an aqueous solution in which nitric acid (concentration 70% by mass) and ultrapure water were mixed at a volume ratio of 1:1 to the obtained 10 mL of the sample for analysis, the volume was diluted to 100 mL with ultrapure water, and the sample for ICP analysis was prepared. adjusted. The absorbance of this ICP analysis sample at a wavelength of 333.749 nm was measured using an ICP emission spectrometer "iCap7000Duo" (manufactured by Thermo Fisher Scientific Co., Ltd.), and the mass concentration (mg/L) of lanthanum atoms was determined. Calculated.
• abrasive slurry which is the test substance
• 0.2 ml of the abrasive slurry was applied to the gauze part of a bandage on five subjects, and after it was thoroughly absorbed, it was applied directly to the inside of each person's forearm, and after 30 minutes had passed, The condition of the skin surface was observed. As rough skin and dermatitis progress, itching and erythema are observed.If no itching or erythema is observed, no change is considered, those with itching are considered to have worsened slightly, and those with slight erythema are considered to be no change.
• polishing pad Suede pad Lower surface plate rotation speed: 260 rpm Pressure during polishing: 100g/cm 2 Polishing time: 20 minutes x 3 pieces
• Each evaluation method is as follows. [Polishing speed] The thickness before and after polishing at five locations per sample was measured with a micrometer, and the average value of the amount of decrease in thickness ( ⁇ T [ ⁇ m]) was determined. The average value of [ ⁇ T/polishing time (20 minutes)] for the three samples was taken as the polishing rate. [Polishing scratches] The polished surface of the polished sample was observed using a differential interference microscope ("BX51M” manufactured by Olympus Corporation) at a magnification of 50 times, the number of scratches was measured, and the average value for the three samples was determined.
• the cerium-based abrasives (Examples 1 to 25) in which the amount of lanthanum dissolved in the mixed liquid obtained by the prescribed method was 40 mg/L or less suppressed the occurrence of rough skin and dermatitis. It was recognized that this was done. Furthermore, it has been found that the polishing liquid containing the cerium-based abrasive material suppresses the occurrence of polishing scratches and allows polishing to be performed at a good polishing rate.

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