Aqueous composition, polishing slurry, and kit for preparing polishing slurry

Abstract

To provide an aqueous composition containing an acid, wherein the aqueous composition is less prone to bacterial propagation and coloration during storage.SOLUTION: The present invention discloses an aqueous composition for polishing an object. The aqueous composition contains an acid, a preservative, and water. The aqueous composition contains, as the preservative, a compound Q free of both sulfur and nitrogen atoms.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an aqueous composition, an abrasive slurry containing the aqueous composition, and an abrasive slurry preparation kit containing the aqueous composition as a component thereof. [Background technology]

[0002] Polishing processes using polishing slurries containing abrasive grains are performed on the surfaces of materials such as metals, semimetals, nonmetals, and their oxides. The polishing slurries can be distributed and stored in the form of an abrasive grain dispersion in which abrasive grains are dispersed in water, and an aqueous composition (hereinafter also referred to as the secondary composition) containing water and at least some of the components other than the abrasive grains (hereinafter also referred to as the secondary components). The secondary composition can be used to polish an object to be polished, for example, by mixing it with the abrasive grain dispersion and dilution water to prepare a polishing slurry, and then supplying the polishing slurry to the object to be polished.

[0003] A preservative may be added to the above-mentioned abrasive dispersion to prevent spoilage during distribution and storage. Patent documents 1 to 3 are cited as technical documents relating to this type of technology. Patent documents 2 and 3 disclose silica dispersions with a pH of 7 or higher containing an organic preservative with a specific structure (

[0030] of Patent document 2,

[0030] of Patent document 3). The above-mentioned silica dispersions do not contain acid. On the other hand, Patent documents 4 and 5 disclose the coloration of the container, which is a problem specific to polishing compositions containing alumina and a preservative (

[0030] of Patent document 4).

[0004] ,

[0013] , Patent Document 5

[0004] ,

[0020] ) have proposed compounds having an isothiazolone group, disulfide compounds, and imidazoline compounds represented by specific formulas. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-064852 [Patent Document 2] Japanese Patent Application Laid-Open No. 2016-124743 [Patent Document 3] Japanese Patent Application Laid-Open No. 2016-124977 [Patent Document 4] Japanese Patent Application Laid-Open No. 2006-206698 [Patent Document 5] Japanese Patent Application Laid-Open No. 2006-176733 Summary of the Invention [Problem to be solved by the invention]

[0005] Aqueous compositions for preparing acidic polishing slurries by mixing with abrasive dispersions contain a relatively high concentration of acid, and so it has been recognized that bacteria are less likely to grow. However, the present inventors have noticed that certain types of bacteria can survive and grow even in such aqueous compositions. When used as a polishing slurry, the growth of bacteria in an acid-containing aqueous composition can cause problems such as the growth of bacteria clogging the filtration filter and adhering to the polishing substrate.

[0006] Therefore, an object of the present invention is to provide an aqueous composition containing an acid, which inhibits bacterial growth and is less likely to become discolored during storage. Another related object is to provide a polishing slurry and a polishing slurry preparation kit containing the aqueous composition. [Means for solving the problem]

[0007] According to this specification, an aqueous composition for use in polishing a polishing target object is provided. The aqueous composition comprises an acid, a preservative, and water. The preservative comprises a compound Q containing neither a sulfur atom (S) nor a nitrogen atom (N). The use of such compound Q as a preservative can inhibit bacterial growth and prevent coloration during storage. Furthermore, compound Q is less likely to cause deterioration in the polishing performance (e.g., removal rate, silica residue) of a polishing slurry containing the aqueous composition, even when the aqueous composition is used after long-term storage.

[0008] In some embodiments of the technology disclosed herein (including aqueous compositions, polishing slurries prepared using the aqueous compositions, and polishing slurry preparation kits containing the aqueous compositions, the same applies hereinafter), a compound having a structure in which a hydroxyl group and an etheric oxygen are bonded to the same carbon can be preferably used as compound Q. By having such a structure, compound Q, which does not contain either S or N, can preferably exhibit the effect of inhibiting bacterial growth in an aqueous composition containing acid. The structure in which a hydroxyl group and an etheric oxygen are bonded to the same carbon can be, for example, a -O-CHOH group. The -O-CHOH group may also constitute a -CH-O-CHOH group.

[0009] The compound Q can be used alone or in combination of two or more. For example, an aliphatic chain compound Q1 having two or more hydroxyl groups can be used in combination with a compound Q2 having a substituent on an aromatic ring in which the hydroxyl group and an ether oxygen are bonded to the same carbon. Such a combination can exhibit a higher antiseptic effect.

[0010] In some embodiments, the pH of the aqueous composition is in the range of 0.5 to 4.0. In an aqueous composition having a pH in this range, the antiseptic effect of compound Q can be preferably exhibited.

[0011] A preferred example of the object to be polished in the technology disclosed herein is a magnetic disk substrate. Among them, a glass substrate or a magnetic disk substrate having a nickel-phosphorus plating layer on its surface is preferred. Hereinafter, a magnetic disk substrate having a nickel-phosphorus plating layer on its surface is also referred to as a "Ni-P substrate" for short. The aqueous composition disclosed herein can be used as a polishing slurry supplied to a substrate to be polished or as a raw material for preparing the polishing slurry in the polishing process carried out in the manufacturing process of a magnetic disk substrate, and can be useful for realizing a high-quality substrate surface. For example, even if the aqueous composition is used after long-term storage, the polishing performance (e.g., polishing rate, silica residue) of a polishing slurry containing the aqueous composition can be suppressed from deteriorating.

[0012] The aqueous composition according to some embodiments further contains abrasive grains in addition to an acid, a preservative, and water. The aqueous composition containing abrasive grains can be used as a polishing slurry to be applied to the surface of an object to be polished, either as is or by adding additives (e.g., volatile components such as hydrogen peroxide), water for dilution, a pH adjuster, additional abrasive grains, etc. as needed.

[0013] The aqueous composition disclosed herein can be preferably mixed with abrasive grains to prepare a polishing slurry to be supplied to the object to be polished. The abrasive grains mixed with the aqueous composition can be in the form of an abrasive grain dispersion. The aqueous composition is preservatively treated with compound Q, thereby inhibiting bacterial growth and reducing the risk of coloration during storage. Furthermore, even after long-term storage, the polishing performance (e.g., removal rate, silica residue) of a polishing slurry containing the aqueous composition can be prevented from deteriorating.

[0014] According to this specification, a polishing slurry is provided which is supplied to an object to be polished and used to polish the object, and which contains any of the aqueous compositions disclosed herein. When polishing using such a polishing slurry, bacterial growth is suppressed and discoloration due to storage is unlikely to occur. Furthermore, even when used after long-term storage, deterioration of polishing performance (e.g., polishing rate, silica residue) can be suppressed.

[0015] According to this specification, for example, a polishing slurry preparation kit can be provided, which includes an abrasive dispersion containing abrasive grains and water, and a sub-composition consisting of any of the aqueous compositions disclosed herein. In the kit, the abrasive dispersion and the sub-composition are stored separately. The polishing slurry preparation kit configured in this manner has good antiseptic properties of the sub-composition and is less likely to discolor during distribution and storage of the kit. Furthermore, even if the polishing slurry is prepared and used after long-term storage of the kit, deterioration of polishing performance can be prevented. DETAILED DESCRIPTION OF THE INVENTION

[0016] Preferred embodiments of the present invention will be described below. It should be noted that matters necessary for carrying out the present invention other than those specifically mentioned in this specification can be understood as design matters for a person skilled in the art based on the prior art in the relevant field. The present invention can be carried out based on the contents disclosed in this specification and the common general technical knowledge in the relevant field.

[0017] <Aqueous composition> The aqueous composition disclosed herein is a composition used for polishing a workpiece, and contains at least an acid, water, and a predetermined preservative. The aqueous composition may contain abrasive grains or may not contain abrasive grains. Abrasive-free aqueous compositions are typically used by mixing them with abrasive grains to prepare a polishing slurry, which is then supplied to the workpiece. The abrasive grains mixed into the aqueous composition may be in the form of an abrasive grain dispersion in which the abrasive grains are dispersed in water. Abrasive-containing aqueous compositions may be directly supplied to the workpiece to be used as a polishing slurry, or may be used by adding water for dilution, additives (e.g., volatile components such as hydrogen peroxide), a pH adjuster, additional abrasive grains, etc., as needed, to prepare a polishing slurry, which is then supplied to the workpiece to be polished. That is, the aqueous composition disclosed herein may be in the form of a polishing slurry supplied directly to a polishing object, in the form of a polishing slurry concentrate diluted and supplied to a polishing object, or in the form of a sub-composition mixed with abrasive grains, other components that may be used as needed, and dilution water to prepare a polishing slurry. The effects of employing the configuration of the present invention can be appropriately achieved in one or more of these aqueous compositions. The aqueous composition in the form of the slurry concentrate or the sub-composition may be concentrated, for example, about 1.5 to 50 times compared to the polishing slurry at the point of use (POU). In some embodiments, the concentration ratio is preferably about 2 to 20 times, and may be about 5 to 15 times, taking into consideration convenience in transportation and storage, and the storage stability of the aqueous composition. The aqueous composition disclosed herein may be diluted according to the concentration ratio and used to prepare a polishing slurry.

[0018] (acid) The acid used in the aqueous composition disclosed herein may be either an inorganic acid or an organic acid. Examples of the organic acid include organic carboxylic acids, organic sulfonic acids, and amino acids each having about 1 to 18 carbon atoms, typically about 1 to 10. The acids may be used alone or in combination of two or more.

[0019] Specific examples of inorganic acids include phosphoric acid (orthophosphoric acid), nitric acid, sulfuric acid, hydrochloric acid, boric acid, sulfamic acid, phosphinic acid, phosphonic acid, pyrophosphoric acid, tripolyphosphoric acid, tetrapolyphosphoric acid, hexametaphosphoric acid, carbonic acid, hydrofluoric acid, sulfurous acid, thiosulfuric acid, chloric acid, perchloric acid, chlorous acid, hydroiodic acid, periodic acid, iodic acid, hydrobromic acid, perbromic acid, bromic acid, chromic acid, and nitrous acid.

[0020] Specific examples of organic acids include citric acid, maleic acid, malic acid, glycolic acid, succinic acid, itaconic acid, malonic acid, iminodiacetic acid, gluconic acid, lactic acid, mandelic acid, tartaric acid, formic acid, acetic acid, propionic acid, butyric acid, adipic acid, oxalic acid, valeric acid, enanthic acid, caproic acid, caprylic acid, pelargonic acid, capric acid, lauric acid, myristic acid, palmitic acid, margaric acid, stearic acid, cyclohexanecarboxylic acid, phenylacetic acid, benzoic acid, crotonic acid, oleic acid, linoleic acid, linolenic acid, ricinoleic acid, and methacrylic acid. , glutaric acid, fumaric acid, phthalic acid, isophthalic acid, terephthalic acid, tartronic acid, glyceric acid, hydroxybutyric acid, hydroxyacetic acid, hydroxybenzoic acid, salicylic acid, isocitric acid, methylenesuccinic acid, gallic acid, ascorbic acid, nitroacetic acid, oxaloacetic acid, chloroacetic acid, dichloroacetic acid, trichloroacetic acid, and other organic carboxylic acids; glycine, alanine, glutamic acid, aspartic acid, valine, leucine, isoleucine, serine, threonine, cysteine, methionine, phenylalanine, tryptophan, tyrosine, proline, Amino acids such as lysine, cystine, glutamine, asparagine, lysine, and arginine; nicotinic acid; picric acid; picolinic acid; phytic acid; 1-hydroxyethylidene-1,1-diphosphonic acid, aminotri(methylenephosphonic acid), ethylenediaminetetra(methylenephosphonic acid), diethylenetriaminepenta(methylenephosphonic acid), ethane-1,1-diphosphonic acid, ethane-1,1,2-triphosphonic acid, ethane-1-hydroxy-1,1-diphosphonic acid, ethanehydroxy-1,1,2-triphosphonic acid, ethane-1 , 2-dicarboxy-1,2-diphosphonic acid, methanehydroxyphosphonic acid, 2-phosphonobutane-1,2-dicarboxylic acid, 1-phosphonobutane-2,3,4-tricarboxylic acid, α-methylphosphonosuccinic acid, aminopoly(methylenephosphonic acid), etc.; organic sulfonic acids such as methanesulfonic acid, ethanesulfonic acid, aminoethanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, 2-naphthalenesulfonic acid, sulfosuccinic acid, 10-camphorsulfonic acid, isethionic acid, taurine, etc.

[0021] The acid may be used in the form of a salt thereof. Examples of the salt include metal salts, ammonium salts, alkanolamine salts, etc. of the inorganic acids and organic acids described above. Examples of the metal salts include alkali metal salts such as lithium salts, sodium salts, and potassium salts. Examples of the ammonium salts include quaternary ammonium salts such as tetramethylammonium salts and tetraethylammonium salts. Examples of the alkanolamine salts include monoethanolamine salts, diethanolamine salts, and triethanolamine salts. Specific examples of salts include alkali metal phosphates and alkali metal hydrogen phosphates such as tripotassium phosphate, dipotassium hydrogen phosphate, potassium dihydrogen phosphate, trisodium phosphate, disodium hydrogen phosphate, and sodium dihydrogen phosphate; alkali metal salts of the organic acids exemplified above; and alkali metal salts of glutamic acid diacetic acid, alkali metal salts of diethylenetriaminepentaacetic acid, alkali metal salts of hydroxyethylethylenediaminetriacetic acid, and alkali metal salts of triethylenetetraminehexaacetic acid. The alkali metal in these alkali metal salts may be, for example, lithium, sodium, or potassium.

[0022] The acid and its salt can be used alone or in combination of two or more (for example, two or three). In some preferred embodiments, an acid can be used in combination with a salt of an acid different from the acid. The acid is preferably an inorganic acid. The acid salt is preferably an inorganic acid salt.

[0023] The acid content in the aqueous composition (when two or more acids are used, the total amount of those acids; the same applies hereinafter unless otherwise specified) may be, for example, 1 g / L or more, preferably 3 g / L or more, and more preferably 5 g / L or more (e.g., 10 g / L or more), from the viewpoint of optimally exerting the effects of the application of the present invention. There is no particular upper limit to the acid content in the aqueous composition, but from the viewpoint of the handleability of the aqueous composition, the solubility of the preservative, etc., it may be, for example, 700 g / L or less, preferably 500 g / L or less, and more preferably 350 g / L or less (e.g., 250 g / L or less). The preferred content of acid in aqueous composition can also vary depending on the purpose and mode of use of this aqueous composition.For example, in the aqueous composition that is diluted and used as polishing slurry or its constituents, from the viewpoint of easily increasing polishing removal rate, the lower limit of the content of acid is advantageously 10g / L or more, preferably 30g / L or more, can be 50g / L or more, 100g / L or more, 125g / L or more, or can be 150g / L or more.In addition, in the aqueous composition that is used as polishing slurry or its constituents as it is or after undergoing treatment (for example, adding additional components such as oxidizing agent, adjusting pH, etc.) to the extent that the concentration of acid does not significantly decrease, from the viewpoint of easily improving the surface quality after polishing, the upper limit of the content of acid can be, for example, 100g / L or less, 70g / L or less, 50g / L or less, 35g / L or less, or 15g / L or less.

[0024] (preservatives) The aqueous composition disclosed herein is characterized by containing, as a preservative, a compound Q that does not contain either a sulfur atom or a nitrogen atom. Compound Q can be used alone or in appropriate combination of two or more types.

[0025] By incorporating a preservative containing compound Q into an aqueous composition, bacterial growth in the aqueous composition can be suppressed. Furthermore, discoloration of the container during storage can be prevented. By using compound Q, which does not contain either sulfur or nitrogen atoms as a preservative, it is possible to impart preservative properties to an acid-containing aqueous composition while suppressing discoloration of the aqueous composition or the container containing the aqueous composition that occurs with the use of preservatives. The absence of sulfur or nitrogen atoms in compound Q is also preferable from the viewpoint of suppressing the residue of abrasive particles on the surface after polishing with a polishing slurry containing the aqueous composition containing compound Q. The reason for this effect is thought to be that compound Q prevents the promotion of the residue of abrasive particles due to the unshared electron pairs of sulfur and nitrogen atoms. However, the present invention is not limited to this mechanism.

[0026] A compound that can exert a desired antiseptic effect in an aqueous composition containing an acid is used as the compound Q. For example, in an antiseptic performance evaluation performed using a test solution containing 0.50 g / L of the compound to be evaluated and 175 g / L of acid, with the remainder being water, and the test solution is added at least twice (preferably three times, more preferably four times), the test bacterial solution is added, and the viable cell counts determined from the measurement sample two days later are 10 cfu / mL or less for all of Penicillium chermesinum, Teratosphaeria acidotherma, and Rhinocladiella.

[0027] Compound Q in the technology disclosed herein is preferably organic compound.Compound Q is the organic compound that does not contain sulfur atom and nitrogen atom, and can preferably achieve the effect of preventing the coloration of the aqueous composition that contains acid during storage and preserving the aqueous composition, and the effect of preventing the increase in the number of residual abrasive grains that is caused by the deterioration of the aqueous composition during polishing with the polishing slurry that contains the aqueous composition, and the effect of preventing the decrease in polishing rate.

[0028] In some embodiments, compound Q is a nonionic organic compound. Such compound Q is preferred because it tends not to be excessively adsorbed to abrasive grains or the object to be polished during polishing with a polishing slurry containing the aqueous composition disclosed herein. This can be advantageous in terms of suppressing the decrease in polishing removal rate and reducing residual abrasive grains.

[0029] In some embodiments, compound Q is a compound that does not contain halogen atoms such as chlorine and bromine.Compound Q that does not contain sulfur atom, nitrogen atom and halogen atom is less likely to cause the coloring of aqueous composition, and tends to easily suppress the residual abrasive grains in the polishing slurry that uses the aqueous composition that contains compound Q.

[0030] In some embodiments, compound Q is preferably a compound that does not have multiple bonds.The term "multiple" in the above-mentioned multiple bonds means double or more.Therefore, the compound that has an aryl group such as a benzene ring is included in the concept of the compound that does not have multiple bonds, except for those that have multiple bonds in addition to the aryl group.Specific examples of multiple bonds referred to here include, but are not limited to, carbon-carbon double bonds, carbon-oxygen double bonds, carbon-nitrogen double bonds, carbon-nitrogen triple bonds, etc.Compound Q that does not have multiple bonds is less likely to cause the coloring of aqueous compositions, and tends to easily suppress the residual abrasive grains in the polishing slurry that uses the aqueous composition that contains compound Q.

[0031] In some embodiments, the molecular weight (chemical formula weight based on the molecular structure) of compound Q may be, for example, 2000 or less, and from the viewpoint of easily exerting a good preservative effect with a small amount (by weight) of use, it is preferably 1000 or less, and may be 500 or less, 300 or less, or 200 or less. Furthermore, from the viewpoint of easily exerting an appropriate preservative effect, the molecular weight of compound Q is suitably 50 or more, preferably 70 or more, and may be 100 or more, or 120 or more.

[0032] In some embodiments, compound Q can be a compound represented by the following general formula (1) or general formula (2).

[0033] [ka] [ka]

[0034] In the general formula (1), R1, R2, and R3 are each independently selected from the group consisting of saturated aliphatic hydrocarbon groups and aromatic groups. The saturated aliphatic hydrocarbon group may be linear, branched, or cyclic. Two or more of R1, R2, and R3 may be bonded to each other to form a ring structure. In some embodiments, R1 preferably has 1 to 3 carbon atoms, more preferably 1 to 2 (e.g., 1). R2 preferably has 1 to 4 carbon atoms, more preferably 1 to 3 (e.g., 2). R3 preferably has 1 to 3 carbon atoms, more preferably 1 to 2 (e.g., 1). Furthermore, in the general formula (1), n ​​is 1 to 3, more preferably 1 to 2 (e.g., 1). In the general formula (2), R4 and R5 are each independently selected from the group consisting of saturated aliphatic hydrocarbon groups and aromatic groups. The saturated aliphatic hydrocarbon group may be linear, branched, or cyclic. R4 and R5 may be bonded to each other to form a ring structure. In some embodiments, the number of carbon atoms in R4 is, for example, 1 to 3, preferably 1 to 2 (e.g., 1). The number of carbon atoms in R5 is, for example, 1 to 3, preferably 1 to 2 (e.g., 1).

[0035] In some embodiments, compound Q may be a combination of one or more compounds represented by the general formula (1) (hereinafter also referred to as compound (1)) and one or more compounds represented by the general formula (2) (hereinafter also referred to as compound (2)) in any weight ratio. Such a combination can exhibit a higher preservative effect. This is likely due to the fact that compound (2) is thought to have stronger preservative properties than compound (1), but compound (2) is less likely to hydrate due to its aromatic ring. Furthermore, the combined use of compound (1) and compound (2) may result in compound (1) promoting the hydration of compound (2), thereby enhancing the activity of compound (2) in the solution, thereby improving preservative properties. The above mechanism is the result of the inventors' speculation, and the technology disclosed herein should not be construed as being limited to the above mechanism. When the above combination is used, the amount of compound (2) used relative to 100 parts by weight of the total amount of compound (1) and compound (2) used can be, for example, 10 parts by weight or more and 90 parts by weight or less.

[0036] In some embodiments, compound Q may preferably be a compound having a structure in which a hydroxyl group and an etheric oxygen are bonded to the same carbon. Compound Q, which does not contain either a sulfur atom or a nitrogen atom, can preferably exhibit the effect of inhibiting bacterial growth in an acid-containing aqueous composition. Compound Q having a structure in which a hydroxyl group and an etheric oxygen are bonded to the same carbon may be a compound represented by the general formula (1) or (2) above. Non-limiting examples of compound Q having a structure in which a hydroxyl group and an etheric oxygen are bonded to the same carbon include compounds represented by the general formula (1) above in which one or both of R and R are CR R groups, and compounds represented by the general formula (2) above in which R and R are CR R groups. Here, R and R are each independently selected from a hydrogen atom and an alkyl group (e.g., a methyl group). Preferably, both R and R are hydrogen atoms. Alternatively, compound Q may be a compound having a structure in which a hydroxyl group and an etheric oxygen are bonded to the same carbon, but which does not correspond to either the general formula (1) or (2) above.

[0037] A preferred example of a structure in which a hydroxyl group and an ether oxygen are bonded to the same carbon is an -O-CHOH group. The -O-CHOH group may constitute a -CH-O-CHOH group. Compound Q having one or more (preferably one or two) such groups can be preferably used as a preservative in the aqueous composition disclosed herein.

[0038] A preferred example of compound Q is an aliphatic chain compound Q1 having two or more hydroxyl groups and a structure in which a hydroxyl group and an ether oxygen are bonded to the same carbon. At least one of the two or more hydroxyl groups is a hydroxyl group contained in the structure in which a hydroxyl group and an ether oxygen are bonded to the same carbon. Compound Q1 may be a compound having one structure in which a hydroxyl group and an ether oxygen are bonded to the same carbon, or a compound having two or more (e.g., two) of the above structures. A preferred specific example of compound Q1 is a compound represented by the above general formula (1), in which R1 and R3 are both CR6R7 groups (e.g., CH2 groups).

[0039] Another preferred example of compound Q is compound Q2, which has one or more (e.g., one or two) substituents on the aromatic ring containing a structure in which the hydroxyl group and the etheric oxygen are bonded to the same carbon atom. Preferred examples of compound Q2 include compounds of general formula (2) in which R5 is a CR6R7 group (e.g., a CH2 group).

[0040] In some embodiments, compound Q can be a combination of one or more compounds Q1 and one or more compounds Q2 in any weight ratio. Such a combination can provide a higher antiseptic effect. The total amount of compound Q2 used relative to 100 parts by weight of the total amount of compound Q1 and compound Q2 can be, for example, 10 parts by weight or more, and can be, for example, 90 parts by weight or less.

[0041] From the viewpoint of easily exerting the antiseptic effect, the content of compound Q in the aqueous composition is, for example, suitably 0.001 g / L or more, preferably 0.005 g / L or more, and may be 0.010 g / L or more, or may be 0.025 g / L or more. Furthermore, from the viewpoint of preventing discoloration and suppressing residual abrasive grains, the content of compound Q in the aqueous composition is suitably 10 g / L or less, preferably 5 g / L or less, and more preferably 2 g / L or less (for example, 1 g / L or less). The preferred content of compound Q in aqueous composition can vary depending on the purpose and mode of use of this aqueous composition.In the aqueous composition to be diluted and used as a polishing slurry or its constituent, from the viewpoint of enhancing antiseptic effect, the lower limit of the content of compound Q can be, for example, 0.01g / L or more, can be 0.05g / L or more, and can be 0.10g / L or more (for example, 0.25g / L or more).In addition, in the aqueous composition to be used as a polishing slurry or its constituent after being treated (for example, by adding additional components such as oxidizing agent, pH adjustment, etc.) to the extent that the concentration of compound Q is not significantly reduced, taking into account the influence on polishing removal rate and the number of remaining abrasive grains, the upper limit of the content of compound Q is, for example, 1g / L or less, preferably 0.5g / L or less, more preferably 0.2g / L or less (for example, 0.1g / L or less).

[0042] (water) The water used in the technology disclosed herein may be ion-exchanged water, pure water, ultrapure water, distilled water, etc. Ion-exchanged water may typically be deionized water.

[0043] (pH) The pH of the aqueous composition disclosed herein is typically less than 7.0, preferably 6.0 or less, and may be 5.0 or less. In some embodiments, the pH of the aqueous composition is suitably 4.5 or less, preferably 4.0 or less, more preferably 3.5 or less, and may be 3.0 or less, or may be 2.5 or less. The preservative effect of compound Q can be more preferably exhibited in an aqueous composition having such a pH. The lower limit of the pH of the aqueous composition is not particularly limited, but may be, for example, 0.5 or more, 0.8 or more, or 1.0 or more, from the viewpoint of the handleability of the aqueous composition, etc. The preferred pH of aqueous composition can vary depending on the purpose and mode of use of the aqueous composition.For example, in the aqueous composition that is diluted and used as a polishing slurry or its constituents, from the viewpoint of the polishing removal efficiency of the polishing slurry, the upper limit of the pH of the aqueous composition is preferably 4.0 or less, may be 3.0 or less, may be 2.5 or less, may be less than 2.0, may be less than 1.7, or may be less than 1.5.The pH of the aqueous composition can be, for example, 0.5 or more or 0.8 or more.In addition, in the aqueous composition that is used as a polishing slurry or its constituents as it is or after being treated to such an extent that the pH does not change significantly, from the viewpoint of easily improving the surface quality after polishing with the polishing slurry, the lower limit of the pH of the aqueous composition is suitably 1.0 or more, may be 1.5 or more, may be 1.7 or more, or may be 2.0 or more. Furthermore, from the viewpoint of the polishing removal efficiency of the polishing slurry, the pH of the aqueous composition is suitably 5.0 or less, preferably 4.0 or less, or may be 3.5 or less, 3.0 or less, or 2.5 or less.

[0044] In the technology disclosed herein, the pH of a liquid (which may be an aqueous composition, abrasive dispersion, polishing slurry, etc.) can be determined by performing three-point calibration using a pH meter and then immersing a glass electrode in the liquid to be measured. Examples of standard buffer solutions include phthalate pH buffer solution: pH 4.01 (25°C), neutral phosphate pH buffer solution: pH 6.86 (25°C), and carbonate pH buffer solution: pH 10.01 (25°C).

[0045] (abrasive grain) The aqueous composition disclosed herein may be in a form containing abrasive grains. The aqueous composition containing abrasive grains can be used as a polishing slurry to be supplied to the surface of an object to be polished, either as is or after dilution, or by adding additives (e.g., volatile components such as hydrogen peroxide), a pH adjuster, additional abrasive grains, etc., as needed.

[0046] The type of abrasive grains that can be contained in the aqueous composition can be selected from the same abrasive grains that can be contained in the abrasive grain dispersion liquid described below, and therefore a duplicated explanation will be omitted.

[0047] In the aqueous composition containing abrasive grains, the content of the abrasive grains is not particularly limited, but is typically 5 g / L or more, preferably 10 g / L or more, and more preferably 20 g / L or more (e.g., 35 g / L or more). By increasing the content of the abrasive grains, a higher polishing rate tends to be achieved. Furthermore, from the viewpoint of the dispersion stability of the abrasive grains, the content is usually suitably 800 g / L or less, and preferably 700 g / L or less (e.g., 600 g / L or less). The preferred content of abrasive grains in an aqueous composition containing abrasive grains may vary depending on the purpose and mode of use of the aqueous composition.In an aqueous composition that is diluted and used as a polishing slurry or a component thereof, from the viewpoint of easily achieving a suitable polishing removal rate in the polishing slurry, the lower limit of the content of abrasive grains is preferably 20 g / L or more, more preferably 50 g / L or more, and may be 100 g / L or more, or may be 200 g / L or more.In addition, in an aqueous composition that is used as a polishing slurry or a component thereof as is or after being treated to such an extent that the concentration of abrasive grains does not decrease significantly, from the viewpoint of easily improving the surface quality after polishing, the upper limit of the content of abrasive grains may be, for example, 300 g / L or less, 200 g / L or less, 100 g / L or less, or 70 g / L or less.

[0048] <Abrasive dispersion liquid> In some embodiments, the aqueous composition disclosed herein can be mixed with an abrasive dispersion to prepare a polishing slurry or a concentrate thereof. The abrasive dispersion typically contains abrasive grains and water to disperse the abrasive grains. The water used in the aqueous composition can be the same as that used in the aqueous composition.

[0049] The material and properties of the abrasive grains are not particularly limited, and inorganic particles, organic particles, and organic-inorganic composite particles can all be used. Specific examples of inorganic particles include oxide particles such as silica particles, alumina particles, cerium oxide particles, chromium oxide particles, titanium dioxide particles, zirconium oxide particles, magnesium oxide particles, manganese dioxide particles, zinc oxide particles, and red iron oxide particles; nitride particles such as silicon nitride particles and boron nitride particles; carbide particles such as silicon carbide particles and boron carbide particles; diamond particles; and carbonates such as calcium carbonate and barium carbonate. Examples of the alumina particles include α-alumina, intermediate aluminas other than α-alumina, and composites thereof. Intermediate alumina refers to alumina particles other than α-alumina, and examples include γ-alumina, δ-alumina, θ-alumina, η-alumina, κ-alumina, and composites thereof. Specific examples of organic particles include polymethyl methacrylate (PMMA) particles, poly(meth)acrylic acid particles, and polyacrylonitrile particles. Here, (meth)acrylic acid refers to acrylic acid and methacrylic acid in a comprehensive sense. The abrasive grains can be used alone or in combination of two or more.

[0050] A suitable example of abrasive grains that can be used in the technology disclosed herein is silica particles. The silica particles can be any type of silica particle primarily composed of silica. Here, silica particles primarily composed of silica refer to particles that are 90% by weight or more, e.g., 95% by weight or more, typically 98% by weight or more, of the particles. Examples of silica particles that can be used include, but are not limited to, colloidal silica, agglomerated silica, precipitated silica (also referred to as precipitated silica), sodium silicate silica, alkoxide silica, fumed silica, dried silica, and detonation silica. Furthermore, silica particles obtained using the above silica particles as raw materials can also be used. Examples of such silica particles include silica particles obtained by subjecting the above raw silica particles (hereinafter also referred to as "raw silica") to one or more treatments selected from heat treatments such as heating, drying, and calcination, pressure treatments such as autoclaving, mechanical treatments such as crushing and grinding, and surface modification. Examples of surface modification include chemical modifications such as the introduction of functional groups and metal modification. The silica particles in the technology disclosed herein may contain one type of silica particles as described above, or two or more types in combination.

[0051] A suitable example of silica particles is colloidal silica. Among them, colloidal silica synthesized through particle growth in an aqueous phase, such as sodium silicate silica or alkoxide silica, is preferably used. Silica abrasives containing this type of colloidal silica can achieve excellent surface quality. When the silica abrasives disclosed herein contain colloidal silica, the colloidal silica contained in the silica abrasives may be one type or two or more types with different manufacturing conditions and / or physical properties. Furthermore, the silica abrasives may be composed of one or more types of colloidal silica, or may be composed of a combination of colloidal silica and silica particles other than colloidal silica. In some embodiments, the abrasives contained in the polishing slurry contain colloidal silica alone. By using colloidal silica alone, better surface quality can be achieved.

[0052] The particle shape of colloidal silica is not particularly limited, and may be, for example, spherical or non-spherical. Specific examples of non-spherical shapes include peanut shapes, cocoon shapes, shapes with protrusions, and rugby ball shapes. The peanut shape may be, for example, the shape of a peanut shell. The protrusion shape may be, for example, the shape of a confetti candy.

[0053] The technology disclosed herein can be preferably implemented in an embodiment in which the polishing slurry supplied to the workpiece is substantially free of alumina particles. Such a polishing slurry prevents quality degradation due to the use of alumina particles. Examples of quality degradation include scratches, dents, residual alumina, and penetration defects. In this specification, "substantially free of alumina particles" means that the proportion of alumina particles in the total solid content of the polishing slurry is 1% by weight or less, more preferably 0.5% by weight or less (e.g., 0.1% by weight or less). A polishing slurry with a 0% by weight proportion of alumina particles, i.e., a polishing slurry containing no alumina particles, is particularly preferred. The polishing slurry disclosed herein can also be preferably implemented in an embodiment in which the polishing slurry is substantially free of α-alumina particles.

[0054] The technology disclosed herein can also be preferably implemented in the embodiment that the polishing slurry that is supplied to object to be polished contains silica particles as abrasive grains, and does not substantially contain particles other than silica particles, that is, non-silica particles.Here, "does not substantially contain non-silica particles" means that the proportion of non-silica particles in the total solid content of the polishing slurry is 1 wt% or less, more preferably 0.5 wt% or less, typically 0.1 wt% or less.In this embodiment, the application effect of the technology disclosed herein can be preferably exhibited.

[0055] In some embodiments, the average secondary particle diameter of the abrasive grains (e.g., silica particles) may be, for example, approximately 10 nm to 500 nm. From the viewpoint of polishing efficiency, etc., in some embodiments, the average secondary particle diameter may be, for example, 25 nm or more, or even 40 nm or more. The technology disclosed herein may also be suitably implemented in embodiments in which the average secondary particle diameter of the abrasive grains is 50 nm or more, 60 nm or more, or 70 nm or more. On the other hand, from the viewpoint of improving the surface quality after polishing, the average secondary particle diameter is suitably, for example, 300 nm or less, and may be 200 nm or less, 150 nm or less, 120 nm or less, or 100 nm or less. The above-mentioned average secondary particle diameter may be preferably applied to abrasive grains used for polishing magnetic disk substrates such as Ni-P substrates and glass substrates.

[0056] The average secondary particle size (volume average particle size) of the abrasive grains can be determined by measuring the particle size based on dynamic light scattering using an abrasive-containing liquid containing abrasive grains as a measurement sample. This particle size measurement can be performed using, for example, a Nikkiso Co., Ltd. "UPA-UT151" model. The same applies to the examples described below.

[0057] The content of abrasive grains in the abrasive grain dispersion is not particularly limited. To allow compact storage and distribution of the abrasive grain dispersion, the content of abrasive grains may be, for example, 10 g / L or more, preferably 20 g / L or more, more preferably 50 g / L or more, 100 g / L or more, 200 g / L or more, or 300 g / L or more. From the viewpoint of the dispersion stability of the abrasive grains, the content is usually suitably 800 g / L or less, and preferably 700 g / L or less (e.g., 600 g / L or less).

[0058] The pH of the abrasive dispersion is not particularly limited and can be selected depending on the material of the abrasive grains, the application of the abrasive dispersion, and the like. The pH of the abrasive dispersion can be selected, for example, from the range of 2.0 to 12.5. In an abrasive dispersion containing silica particles as abrasive grains, the pH of the abrasive dispersion (silica dispersion) can be, for example, 5.0 or higher, 7.0 or higher, 8.0 or higher, or 9.0 or higher. As the pH of the silica dispersion increases, the dispersion stability of the silica dispersion tends to improve. Furthermore, from the viewpoint of preventing dissolution of the silica particles, the pH of the silica dispersion is usually suitably 12.0 or lower, preferably 11.0 or lower, and may be 10.5 or lower, for example, 10.0 or lower.

[0059] <Polishing slurry> The polishing slurry containing the aqueous composition disclosed herein may optionally contain, for example, one or more of the components exemplified below as components to be newly mixed with the aqueous composition (which may be components contained in the abrasive dispersion mixed with the aqueous composition).

[0060] The polishing slurry disclosed herein can contain an oxidizing agent if necessary.Examples of oxidizing agents include, but are not limited to, peroxide, nitric acid or its salt, periodic acid or its salt, peroxo acid or its salt, permanganic acid or its salt, chromic acid or its salt, oxyacid or its salt, metal salts, sulfuric acid, etc.One oxidizing agent can be used alone or two or more can be used in combination. Specific examples of the oxidizing agent include hydrogen peroxide, sodium peroxide, barium peroxide, nitric acid, iron nitrate, aluminum nitrate, ammonium nitrate, peroxomonosulfuric acid, ammonium peroxomonosulfate, metal peroxomonosulfates, peroxodisulfate, ammonium peroxodisulfate, metal peroxodisulfates, peroxolinic acid, peroxosulfuric acid, sodium peroxoborate, performic acid, peracetic acid, perbenzoic acid, perphthalic acid, hypobromous acid, hypoiodous acid, chloric acid, bromic acid, iodic acid, periodic acid, perchloric acid, hypochlorous acid, sodium hypochlorite, calcium hypochlorite, potassium permanganate, metal chromates, metal dichromates, iron chloride, iron sulfate, iron citrate, ammonium iron sulfate, etc. Preferred oxidizing agents include hydrogen peroxide, iron nitrate, periodic acid, peroxomonosulfuric acid, peroxodisulfuric acid, and nitric acid. It preferably contains at least hydrogen peroxide, and more preferably consists of hydrogen peroxide.

[0061] When oxidizing agent is contained in polishing slurry, the content of this oxidizing agent is not particularly limited, and can be set so as to achieve desired use effect.In some embodiments, the content of oxidizing agent is preferably 1g / L or more, more preferably 3g / L or more, and even more preferably 4g / L or more.By increasing the content of oxidizing agent, the speed of oxidizing the object to be polished (for example, magnetic disk substrate such as Ni-P substrate) can be increased, and the polishing removal rate can be improved.In addition, the content of oxidizing agent in polishing slurry can be, for example, 50g / L or less, preferably 30g / L or less, and can be 20g / L or less, or 15g / L or less, taking into consideration the surface quality after polishing.

[0062] The polishing slurry disclosed herein may further contain, as necessary, known additives that can be used in polishing slurries, such as surfactants, water-soluble polymers, dispersants, chelating agents, basic compounds, etc., to the extent that the effects of the present invention are not significantly impaired.

[0063] The surfactant is not particularly limited, and any of anionic surfactants, nonionic surfactants, cationic surfactants, and amphoteric surfactants can be used. The use of a surfactant can improve the dispersion stability of the polishing slurry. The surfactant can be used alone or in combination of two or more. The surfactant typically has a molecular weight of 1×10 4 The water-soluble organic compound may be less than 1000 ppm. Specific examples of anionic surfactants include polyoxyethylene alkyl ether acetates, polyoxyethylene alkyl sulfates, alkyl sulfates, polyoxyethylene alkyl sulfates, alkyl sulfates, alkyl benzene sulfonates, alkyl phosphates, polyoxyethylene alkyl phosphates, polyoxyethylene sulfosuccinates, alkyl sulfosuccinates, alkyl naphthalene sulfonates, alkyl diphenyl ether disulfonic acids, polyacrylic acids, sodium lauryl sulfate, ammonium lauryl sulfate, sodium dodecylbenzene sulfonate, polyoxyethylene alkyl ether sodium sulfate, polyoxyethylene alkyl phenyl ether ammonium sulfate, polyoxyethylene alkyl phenyl ether sodium sulfate, and salts thereof. Other specific examples of anionic surfactants include polyalkylarylsulfonic acid compounds such as naphthalenesulfonic acid-formaldehyde condensates, methylnaphthalenesulfonic acid-formaldehyde condensates, anthracenesulfonic acid-formaldehyde condensates, and benzenesulfonic acid-formaldehyde condensates; melamine-formaldehyde resin sulfonic acid compounds such as melamine sulfonic acid-formaldehyde condensates; ligninsulfonic acid compounds such as ligninsulfonic acid and modified ligninsulfonic acid; aromatic aminosulfonic acid compounds such as aminoarylsulfonic acid-phenol-formaldehyde condensates; polyisoprene sulfonic acid, polyvinylsulfonic acid, polyallylsulfonic acid, polyisoamylenesulfonic acid, polystyrenesulfonic acid; and salts thereof. Alkali metal salts such as sodium salts and potassium salts are preferred as salts. Specific examples of nonionic surfactants include polyoxyethylene alkyl ethers, polyoxyalkylene alkyl ethers, sorbitan fatty acid esters, glycerin fatty acid esters, polyoxyethylene fatty acid esters, polyoxyethylene alkylamines, and alkylalkanolamides. Specific examples of cationic surfactants include alkyltrimethylammonium salts, alkyldimethylammonium salts, alkylbenzyldimethylammonium salts, and alkylamine salts. Specific examples of amphoteric surfactants include alkyl betaine type, fatty acid amidopropyl betaine type, alkyl imidazole type, amino acid type, and alkyl amine oxide type.

[0064] In the polishing slurry of an embodiment containing a surfactant, the content of the surfactant can be, for example, 0.005 g / L or more. From the viewpoint of the smoothness of the surface after polishing, the content is preferably 0.01 g / L or more, more preferably 0.1 g / L or more. In addition, taking into consideration the polishing removal rate, the content is suitably 100 g / L or less, preferably 50 g / L or less, for example 10 g / L or less. The technology disclosed herein can also be preferably implemented in an embodiment in which a surfactant is not substantially used. Here, "not substantially used" means that a surfactant is not used at least intentionally.

[0065] The polishing slurry disclosed herein may contain a water-soluble polymer. By including a water-soluble polymer, the surface precision after polishing can be improved. Examples of water-soluble polymers include polyalkylarylsulfonic acid compounds such as naphthalenesulfonic acid formaldehyde condensate, methylnaphthalenesulfonic acid formaldehyde condensate, and anthracenesulfonic acid formaldehyde; melamine formalin resin sulfonic acid compounds such as melamine sulfonic acid formaldehyde condensate; ligninsulfonic acid compounds such as ligninsulfonic acid and modified ligninsulfonic acid; aromatic aminosulfonic acid compounds such as aminoarylsulfonic acid-phenol-formaldehyde condensate; and others, such as polyisoprene sulfonic acid, polyvinyl sulfonic acid, and polyallyl sulfonic acid. Examples of water-soluble polymers include sulfonic acid, polyisoamylene sulfonic acid, polystyrene sulfonate, polyacrylate, polyvinyl acetate, polymaleic acid, polyitaconic acid, polyvinyl alcohol, polyglycerin, polyvinylpyrrolidone, copolymers of isoprene sulfonic acid and acrylic acid, polyvinylpyrrolidone-polyacrylic acid copolymers, polyvinylpyrrolidone-vinyl acetate copolymers, diallylamine hydrochloride-sulfur dioxide copolymers, carboxymethyl cellulose, salts of carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, pullulan, chitosan, chitosan salts, etc. The water-soluble polymers can be used alone or in combination of two or more.

[0066] In the polishing slurry of the embodiment containing water-soluble polymer, the content of the water-soluble polymer in the polishing slurry is suitably, for example, 0.01g / L or more.From the viewpoint of surface smoothness after polishing, the content is preferably 0.05g / L or more, more preferably 0.08g / L or more, and even more preferably 0.1g / L or more.In addition, from the viewpoint of polishing removal rate, the content is suitably 10g / L or less, preferably 5g / L or less, for example 1g / L or less.The technology disclosed herein can also be preferably implemented in an embodiment in which water-soluble polymer is not substantially used.Here, "not substantially used" means that at least not used intentionally.

[0067] Examples of dispersants include polycarboxylic acid-based dispersants such as sodium polycarboxylic acid salts and ammonium polycarboxylic acid salts; naphthalenesulfonic acid-based dispersants such as sodium naphthalenesulfonate and ammonium naphthalenesulfonate salts; alkylsulfonic acid-based dispersants; polyphosphate-based dispersants; polyalkylenepolyamine-based dispersants; quaternary ammonium-based dispersants; alkylpolyamine-based dispersants; alkylene oxide-based dispersants; and polyhydric alcohol ester-based dispersants.

[0068] Examples of chelating agents include aminocarboxylic acid chelating agents and organic phosphonic acid chelating agents. Of these, organic phosphonic acid chelating agents are more preferred, and particularly preferred are ethylenediaminetetrakis(methylenephosphonic acid) and diethylenetriaminepenta(methylenephosphonic acid). A particularly preferred chelating agent is ethylenediaminetetrakis(methylenephosphonic acid).

[0069] The polishing slurry may contain one or more basic compounds as needed for purposes such as pH adjustment. Examples of basic compounds include alkali metal hydroxides such as potassium hydroxide and sodium hydroxide; carbonates and bicarbonates such as ammonium bicarbonate, ammonium carbonate, potassium bicarbonate, potassium carbonate, sodium bicarbonate, and sodium carbonate; quaternary ammonium compounds; ammonia; etc. The basic compound contained in the polishing slurry may be derived from an aqueous composition or an abrasive dispersion.

[0070] The pH of the polishing slurry is not particularly limited and can be appropriately set depending on the purpose and mode of use of the polishing slurry. The pH of the polishing slurry can be, for example, 12.0 or less, typically 0.5 to 12.0, or 10.0 or less, typically 0.5 to 10.0. From the viewpoint of the polishing removal rate and surface quality after polishing, the pH of the polishing slurry can be 7.0 or less, for example, 0.5 to 7.0, more preferably 5.0 or less, typically 1.0 to 5.0, and even more preferably 4.0 or less, for example, 1.0 to 4.0. The pH of the polishing slurry can be, for example, 3.0 or less, typically 1.0 to 3.0, preferably 1.0 to 2.5 (e.g., 1.5 to 2.5). The above pH is preferably applied to a polishing slurry used for polishing a nickel-phosphorus substrate, for example. In particular, it is preferably applied to a polishing slurry for primary polishing of a nickel-phosphorus substrate.

[0071] The polishing slurry containing the aqueous composition disclosed herein may be a single-component type, or may be a multi-component type such as a two-component type. The multi-component polishing slurry may be prepared by, for example, mixing the abrasive dispersion and the sub-component consisting of the aqueous composition with water and other components as needed.

[0072] The aqueous composition disclosed herein can be preferably used as a component of a polishing slurry preparation kit. In particular, it is suitable as a component of a kit for preparing a polishing slurry by mixing the aqueous composition with an abrasive dispersion. Such a kit can be configured to include at least a first composition comprising the above-described abrasive dispersion and a second composition comprising any of the aqueous compositions disclosed herein. Here, the first composition and the second composition are preferably stored separately.

[0073] The polishing slurry containing the aqueous composition disclosed herein can be preferably used for polishing, for example, nickel phosphorus substrates, glass substrates, carbon substrates, etc. Furthermore, the plating material may be a disk substrate having a metal layer or metal compound layer other than a nickel phosphorus plating layer on the surface of the substrate disk. In particular, the aqueous composition disclosed herein is suitable as a polishing slurry for nickel phosphorus-plated substrates having a nickel phosphorus plating layer on an aluminum alloy substrate disk. For such applications, the application of the technology disclosed herein is particularly meaningful.

[0074] The polishing slurry containing the aqueous composition disclosed herein can be particularly useful in applications where it is desired to reduce the number of residual abrasive grains on the surface after polishing.A suitable example of such an application is the pre-polishing step carried out before the above-mentioned finish polishing step in the manufacturing process of a magnetic disk substrate, which requires a high-precision surface after the finish polishing step.If there are multiple pre-polishing steps before the finish polishing step, the polishing slurry can be used in any of the pre-polishing steps, and the same or different polishing slurries can be used in these pre-polishing steps.The polishing slurry containing the aqueous composition disclosed herein is suitable, for example, as a polishing slurry used in the first polishing step of a magnetic disk substrate.In particular, it can be preferably used in the first polishing step after nickel phosphorus plating, i.e., the first polishing step, in the manufacturing process of a nickel phosphorus substrate.

[0075] The polishing slurry disclosed herein is suitable for polishing a magnetic disk substrate having a surface roughness of approximately 20 Å to 300 Å as measured by a laser scanning surface roughness meter "TMS-3000WRC" manufactured by Schmitt Measurement System Inc., for example, and adjusting the surface roughness of the magnetic disk substrate to 10 Å or less. For such applications, it is particularly useful to apply the technology disclosed herein. The surface roughness referred to here refers to the arithmetic mean roughness (Ra).

[0076] <Polishing method> A polishing slurry containing the aqueous composition disclosed herein (which may be a polishing slurry prepared using the aqueous composition disclosed herein) can be suitably used for polishing an object to be polished, for example, in an embodiment including the following operations. A preferred embodiment of a method for polishing an object to be polished using the polishing slurry disclosed herein will be described below. Hereinafter, the object to be polished will also be referred to as a substrate to be polished or simply as a substrate. That is, a polishing slurry (working slurry) containing any of the aqueous compositions disclosed herein is prepared. Then, the polishing slurry is supplied to an object to be polished, and polished by a conventional method. For example, the object to be polished is set in a general polishing device, and the polishing slurry is supplied to the surface of the object to be polished, i.e., the surface to be polished, through the polishing pad of the polishing device. Typically, while the polishing slurry is continuously supplied, the polishing pad is pressed against the surface of the object to be polished, and the two are moved relative to each other. The movement can be, for example, a rotational movement. Through this polishing process, the polishing of the object to be polished is completed.

[0077] The polishing pad that can be used is not particularly limited. For example, polishing pads such as hard foam polyurethane type, nonwoven fabric type, and suede type can be used. The suede type may be a buff pad or a polishing pad in a non-buffed state (so-called non-buff pad) whose surface has not been buffed. Such suede type polishing pads (typically polyurethane polishing pads) are easy to process and easily achieve high-quality substrate surfaces. The polishing pads used in the technology disclosed herein are typically polishing pads that do not contain abrasive grains.

[0078] After polishing (specifically, after the primary polishing of the magnetic disk substrate), it is preferable to wash the substrate (washing step). The washing step is typically carried out using a washer. In the washing step, a washing liquid may be used, or washing may be carried out using only running water without using a washing liquid. Ultrasonic treatment may be carried out by applying ultrasonic waves to the substrate immersed in the washing liquid or water. By carrying out such a washing step, abrasive grains remaining on the substrate after polishing can be efficiently removed.

[0079] The polishing machine used in the polishing step may be a double-sided polishing machine that polishes both sides of the object to be polished simultaneously, or a single-sided polishing machine that polishes only one side of the object to be polished. When the polishing step is a preliminary polishing step, in some embodiments, a double-sided polishing machine can be preferably used as the polishing machine that performs the polishing step. When a finish polishing step is performed after the primary polishing step, a single-sided polishing machine can be preferably used as the polishing machine that performs the finish polishing step.

[0080] The polishing step as described above can be part of a manufacturing process for a magnetic disk substrate, such as a nickel phosphorus substrate. Therefore, this specification provides a method for manufacturing and polishing a magnetic disk substrate, which includes the polishing step.

[0081] The aqueous composition disclosed herein can be preferably used as a polishing slurry or a component thereof for a preliminary polishing step of an object to be polished, such as a primary polishing step. This specification provides a method for manufacturing and polishing a magnetic disk substrate, including a step of performing preliminary polishing using a polishing slurry containing any of the aqueous compositions described above. The method includes step (1) of supplying the polishing slurry to the object to be polished to polish the object. The method may include a final polishing step after the preliminary polishing step. The polishing slurry used in the final polishing step is not particularly limited. Therefore, the subject matter disclosed herein includes a method for manufacturing and polishing a magnetic disk substrate, including, in this order, step (1) of polishing the object to be polished with a polishing slurry containing the aqueous composition disclosed herein, and step (2) of polishing the object to be polished with a polishing slurry different from the polishing slurry used in step (1) (e.g., a final polishing slurry). This manufacturing method allows for efficient production of magnetic disk substrates.

[0082] The abrasive grains used in step (2) are not particularly limited, and for example, colloidal silica is preferably used. By using colloidal silica, a polished product with high surface precision can be efficiently produced. The particle shape of the colloidal silica is not particularly limited, and may be, for example, spherical or non-spherical. In some embodiments, spherical colloidal silica is preferably used.

[0083] The final polishing slurry used in step (2) contains water in addition to abrasive grains, and may contain other components (such as acids, oxidizing agents, basic compounds, and various additives) similar to those of the polishing slurry described above, as needed. [Example]

[0084] Hereinafter, several examples of the present invention will be described, but it is not intended that the present invention be limited to those shown in these examples.

[0085] Experimental Example 1: Preparation and Evaluation of Abrasive-Free Aqueous Composition (Examples A1 to A11 and Comparative Examples A2 to A7) Acid, preservative, and deionized water were mixed to prepare aqueous compositions having the composition and pH shown in Table 1. In Table 1, the abbreviations a to g indicating the types of preservatives respectively represent the compounds shown in Table 2 (the same applies hereinafter).

[0086] (Examples A12 to A14) Aqueous compositions having the formulations and pHs shown in Table 1 were prepared in the same manner as in the preparation of the aqueous composition of Example A9, except that the pH was adjusted using potassium hydroxide.

[0087] (Comparative Example A1) Aqueous compositions having the compositions and pHs shown in Table 1 were prepared in the same manner as in the preparation of the aqueous composition of Example A1, except that no preservatives were used.

[0088] (Evaluation of anti-discoloration properties during storage) 2000 g of the aqueous composition according to each example was placed in a 2000 mL transparent polypropylene container and stored at 70°C for 168 hours or 336 hours, respectively. After storage, the aqueous composition (contents) was removed from the container, the inside of the container was washed with water, and the presence or absence of discoloration was determined by visual comparison with an unused container. The aqueous composition (contents) removed from the container was also visually compared with the aqueous composition immediately after preparation (specifically, 3 hours at room temperature after mixing the ingredients; the same applies below) to determine the presence or absence of discoloration. From the results obtained, the storage discoloration resistance of the aqueous compositions was evaluated using the following three levels, and the results are shown in Table 1. The higher the score, the better the storage discoloration resistance. 2 points: No discoloration was observed in either the container or the aqueous composition after storage for 168 hours or 336 hours. 1 point: No discoloration was observed in either the container or the aqueous composition after 168 hours of storage, but discoloration was observed in at least one of the container and the aqueous composition after 336 hours of storage. 0 points: After 168 hours of storage, discoloration was observed in at least one of the container and the aqueous composition.

[0089] (Method for evaluating antiseptic performance) Three types of bacteria (Penicillium chermesinum, Teratosphaeria acidotherma, and Rhinocladiella) were transferred to potato dextrose agar medium and cultured at 25°C ± 2°C for 7 days. Spores were extracted from the cultured bacteria using a sterilized 0.005% dioctyl sodium sulfosuccinate solution, and the spore count was then counted at 10 5 The test bacterial solution was prepared by adjusting the concentration to about 1 / mL. The aqueous composition according to each example was dispensed in 100 g portions into clean containers, and 1 g of the test bacterial solution was added to each sample every two days. The samples were then cultured in a thermostatic chamber adjusted to 28±2°C to prepare measurement samples. After the culture, the viable bacterial count was counted every two days. The viable bacterial count was measured by dividing the measurement samples into 10, 10 2 The solution was serially diluted 1:1 and dispensed into petri dishes in 1 mL portions, and then potato dextrose agar medium was added, stirred well, and left to stand. After the medium had solidified, it was placed in an incubator adjusted to 28°C ± 2°C and cultured for 3 to 5 days, and the number of grown colonies was counted to determine the number of viable bacteria. The above-mentioned addition of the test bacterial solution every two days was repeated up to eight times to evaluate the preservative performance. In the above-mentioned viable count measurement, if the viable counts of all three types of bacteria were 10 cfu / mL or less, the score was "2 points." If the viable counts of all three types of bacteria were 100 cfu / mL or less and the viable count of at least one of the three types of bacteria was greater than 10 cfu / mL, the score was "1 point." If the viable count of at least one of the three types of bacteria was greater than 100 cfu / mL, the score was "1 point." The results are shown in Table 1. The higher the score, and the higher the score maintained over the course of the test bacterial solution addition, the better the preservative performance.

[0090] <Experimental Example 2: Preparation and Evaluation of Polishing Slurry> In the following Experimental Example 2, the aqueous composition prepared in Experimental Example 1 was used as a sub-composition for mixing with abrasive grains to prepare a polishing slurry.

[0091] Example C1 Silica particles (colloidal silica with an average secondary particle diameter of 80 nm) as abrasive grains, (ethylenedioxy)dimethanol (preservative a shown in Table 2) as a preservative, and deionized water were mixed to prepare an abrasive grain dispersion having the composition shown in Table 3. The above abrasive dispersion and aqueous composition A1 prepared in Experimental Example 1 were both used immediately after preparation (i.e., after 3 hours at room temperature) to prepare a polishing slurry having the composition shown in Table 3. The polishing slurry was prepared by adding 100 mL of the above abrasive dispersion and 100 mL of the above aqueous composition (sub-composition), and then adding 12 g of an active ingredient of an aqueous hydrogen peroxide solution and deionized water to make a total volume of 1000 mL, and mixing them.

[0092] The abrasive dispersion prepared above and the aqueous composition A1 prepared in Experimental Example 1 were each placed in a 2000 mL transparent polypropylene container and stored at 70°C for 168 hours. The amount placed in each container was 2000 g. After the liquid temperatures of the abrasive dispersion and the aqueous composition after storage were lowered to 23°C, 100 mL of the abrasive dispersion and 100 mL of the aqueous composition (subcomposition) were added, and then 12 g of an active ingredient of an aqueous hydrogen peroxide solution and deionized water were added to make a total volume of 1000 mL, and mixed to prepare a polishing slurry having the composition shown in Table 3.

[0093] (Examples C2, C5, C10 to C11 and Comparative Examples C2 to C7) An abrasive dispersion liquid having the composition shown in Table 3 was prepared by mixing silica particles (colloidal silica with an average secondary particle diameter of 80 nm) as abrasive particles, an antiseptic, and deionized water. This abrasive dispersion and each aqueous composition shown in Table 3 (each aqueous composition (sub-composition) prepared in Examples A2, A5, A10 to A11, and Comparative Examples A2 to A7) were used immediately after preparation or after storing at 70°C for 168 hours, and polishing slurries with the compositions shown in Table 3 were prepared in the same manner as in Example C1 in all other respects.

[0094] (Comparative Example C1) An abrasive dispersion having the composition shown in Table 3 was prepared in the same manner as in the preparation of the abrasive dispersion of Example C1, except that no preservative was used. This abrasive dispersion and the aqueous composition prepared in Comparative Example A1 were used either immediately after preparation or after storing at 70°C for 168 hours, and the other points were the same as in Example C1 to prepare a polishing slurry having the composition shown in Table 3.

[0095] The following polishing test was carried out on the day each polishing slurry was prepared, and the number of residual silica particles and the polishing removal rate were evaluated to investigate the influence of storing the compositions (abrasive dispersion and sub-composition) used to prepare the polishing slurry on the number of residual silica particles and the polishing removal rate. The number of residual silica particles and the polishing removal rate were evaluated using the following method. The pH of each polishing slurry at the time of supply to the polishing object (POU) was 2.2.

[0096] (Polishing test) The polishing slurry according to each example was directly applied to the object to be polished, and the object was polished under the following conditions. The object to be polished was an aluminum substrate for hard disks (substrate to be polished) with an electroless nickel-phosphorus plating layer on its surface. The substrate was doughnut-shaped, with a diameter of 3.5 inches, an outer diameter of approximately 95 mm, an inner diameter of approximately 25 mm, and a thickness of 1.75 mm, and its surface roughness Ra before polishing was 130 Å. [Polishing conditions] Polishing equipment: Speedfam double-sided polishing machine, model "9.0B-5P" Polishing pad: Suede pad manufactured by FILWEL, product name "CR200" (a pad having a base layer and a surface layer, the surface layer being made of foamed polyurethane) Number of substrates to be polished: 10 (2 substrates / carrier x 5 carriers) Polishing slurry supply rate: 90 mL / min Polishing load: 100g / cm 2 Upper surface plate rotation speed: 27 rpm Lower surface plate rotation speed: 36rpm Sun gear rotation speed: 8 rpm Polishing amount: Total thickness of both sides of each substrate: approx. 2.0 μm The amount of polishing was calculated based on the following formula. Polishing amount [μm] = weight loss of substrate due to polishing [g] / (substrate area [cm 2 ] × density of nickel phosphorus plating [g / cm 3 ]) x 10 4

[0097] (Calculation of polishing removal rate) For each example, the polishing removal rate on both sides of the substrate to be polished under the above polishing conditions was calculated using a polishing slurry prepared using the abrasive dispersion and the sub-composition immediately after preparation (after 3 hours at room temperature) or after 168 hours of storage at 70°C, based on the following calculation formula. Polishing removal rate [μm / min] = weight loss of substrate due to polishing [g] / (substrate area [cm 2 ] × density of nickel phosphorus plating [g / cm 3 ] × polishing time [min]) × 10 4

[0098] The results were converted into relative values, with the polishing removal rate of the polishing slurry using the abrasive dispersion and sub-composition immediately after preparation being set at 100, and are shown in the "Polishing Removal Rate" column in Table 3. If the polishing removal rate decreases by less than 10% (relative value greater than 90) when preparing a polishing slurry using the material stored at 70°C for 168 hours, the decrease in storage stability due to the use of the preservative is judged to be within an acceptable range. If the decrease in the polishing removal rate is 5% or less (relative value 95 or more), it is judged to exhibit good storage stability, and if it is 2% or less (relative value 98 or more), it is judged to exhibit excellent storage stability.

[0099] (Measurement of the number of residual silica particles) The substrates polished under the same conditions as those used to measure the polishing rate were washed using a cleaning machine manufactured by CRESEN, and the number of particles remaining on the substrate surface was then measured. Specifically, the substrates were washed in running water without using a brush or cleaning agent, and water droplets adhering to the substrates were removed using a spin dryer, followed by drying. The specific cleaning conditions were as follows: (Washing conditions) Cleaning agent application time: 0 seconds Disk substrate rotation speed during cleaning: 40 rpm First wash time (running water only): 15 seconds First wash flow rate: 750 mL / min Second wash time (running water only): 20 seconds Second wash flow rate: 900 mL / min Ultrasonic cleaning time (running water only): 20 seconds Ultrasonic cleaning flow rate: 3000 mL / min Spin dry time: 20 seconds Spin dry rotation speed: 3000 rpm Next, the cleaned substrate surfaces (both sides) were observed at 50,000x magnification using a Hitachi High-Technologies Corporation "SU8000" scanning electron microscope, with 10 fields per side. Then, using Mitani Corporation's "WinROOF" image analysis software, the number of residual silica particles in each field was measured, and the average number of residual silica particles per field was calculated. The results were converted into relative values, with the polishing removal rate of the polishing slurry containing the abrasive dispersion and auxiliary composition immediately after preparation being set at 100, and are shown in the "Residual Silica Count" column in Table 3. If the increase in the number of residual silica particles due to the use of a preservative is less than 10% (relative value less than 110) when preparing a polishing slurry using the material stored at 70°C for 168 hours, the increase in the number of residual silica particles due to the use of a preservative is considered to be within the acceptable range.

[0100] [Table 1]

[0101] [Table 2]

[0102] [Table 3]

[0103] As shown in Table 1, the aqueous compositions of Examples A1 to A14, which used a preservative corresponding to compound Q, exhibited significantly higher antiseptic properties and also had excellent storage coloration prevention properties compared to the aqueous composition of Comparative Example A1, which did not contain a preservative. Furthermore, as can be seen from the comparison of Examples A1, A2, and A3, for example, the use of a combination of preservative a and preservative b achieved a higher antiseptic effect than the use of preservative a or preservative b alone. Furthermore, as shown in Table 3, the aqueous compositions of Examples A1, A2, A5, and A10 to A11 showed little increase in the number of residual silica particles and little decrease in the polishing removal rate, even when used to prepare polishing slurries after storage, and thus had excellent storage stability. On the other hand, the aqueous compositions of Comparative Examples A1 to A7, which used only preservatives that did not correspond to Compound Q, were inferior to the aqueous compositions of the above Examples in one or more of the following: preservative properties, prevention of discoloration during storage, suppression of an increase in the number of residual silica particles due to use after storage, and suppression of a decrease in the polishing removal rate.

[0104] Although specific examples of the present invention have been described above in detail, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and alterations of the specific examples exemplified above.

Claims

1. An aqueous composition used for polishing an object to be polished, comprising: The aqueous composition comprises an acid, a preservative, and water; The preservative comprises a compound Q that does not contain any of a sulfur atom and a nitrogen atom, As the compound Q, an aliphatic chain compound Q1 having two or more hydroxyl groups; A compound Q2 having, on an aromatic ring, a substituent containing a structure in which a hydroxyl group and an ether oxygen are bonded to the same carbon; in combination.

2. An aqueous composition for use in polishing an object to be polished, comprising: The aqueous composition comprises an acid, a preservative, and water; The preservative comprises a compound Q that does not contain any of a sulfur atom and a nitrogen atom, An aqueous composition comprising, as the compound Q, a compound Q2 having, on an aromatic ring, a substituent containing a structure in which a hydroxyl group and an etheric oxygen are bonded to the same carbon.

3. The compound Q has a structure in which the hydroxyl group and the ether oxygen are bonded to the same carbon, and the structure is represented by the formula: ２ 3. The aqueous composition of claim 1, which comprises OH groups.

4. 4. The aqueous composition according to claim 1, wherein the pH is in the range of 0.5 to 4.

0.

5. The aqueous composition according to any one of claims 1 to 4, wherein the object to be polished is a magnetic disk substrate.

6. The aqueous composition according to any one of claims 1 to 5, further comprising an abrasive.

7. The aqueous composition according to any one of claims 1 to 5, which is used to prepare a polishing slurry by mixing with abrasive grains and supplying to an object to be polished.

8. 8. A polishing slurry to be supplied to an object to be polished and used for polishing the object, comprising the aqueous composition according to claim 1.

9. an abrasive dispersion liquid containing abrasive grains and water; A sub-composition comprising the aqueous composition according to any one of claims 1 to 5; Including, The abrasive grain dispersion liquid and the sub-composition are stored separately from each other in the abrasive slurry preparation kit.

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