JP6148858B2 - Polishing liquid composition for magnetic disk substrate - Google Patents

Description

  The present disclosure relates to a polishing liquid composition for a magnetic disk substrate and a method for producing a magnetic disk substrate using the same.

  In recent years, magnetic disk drives have been reduced in size and capacity, and high recording density has been demanded. In order to achieve a high recording density, it is necessary to reduce the flying height of the magnetic head in order to improve the detection sensitivity of the weakened magnetic signal by reducing the unit recording area. The magnetic disk substrate responds to the low flying height of the magnetic head and the reduction of the recording area. Therefore, the smoothness and flatness are improved (reduction of surface roughness, waviness and edge sagging) and defects are reduced (scratches, protrusions, pits). Etc.) is becoming stricter. Furthermore, the recording system for magnetic disks is shifting from a horizontal magnetic recording system to a perpendicular magnetic recording system in response to a request for an increase in recording capacity. In the manufacturing process of the perpendicular magnetic recording type magnetic disk substrate, the magnetic layer is formed without going through the texturing process. For this reason, the required characteristics for the substrate are more severe.

  Patent Document 1 discloses a method for manufacturing a hard disk substrate using a polishing composition containing an oxyalkylene ether sulfate having a specific structure for the purpose of reducing roll-off.

  Patent Document 2 proposes a magnetic disk polishing liquid composition containing an anionic polymer having at least one of a sulfonic acid group and a carboxylic acid group. By using this polishing liquid composition, silica particles are bonded to each other. A technique is disclosed in which the number of scratches is reduced by suppressing the agglomeration and suppressing the friction between the polishing pad and the substrate to be polished.

  Patent Document 3 discloses a polishing liquid composition containing an aliphatic amine compound or an alicyclic amine compound, and according to this polishing liquid composition, the Ni microcrystalline portion of the Ni-P plating layer has A technique for reducing the number of scratches by forming a protective layer by adsorbing to an amorphous Ni-P plating layer with little adsorption is disclosed.

  Patent Document 4 discloses an abrasive for a magnetic recording medium substrate using alumina particles for the purpose of lowering the surface roughness and improving the polishing rate.

JP 2007-130728 A Japanese Patent Application No. 2009-131947 JP 2011-131346 A International Publication No. 98/21289

  However, these techniques cannot sufficiently satisfy the number of scratches and productivity required for the substrate surface with the recent shift to the perpendicular magnetic recording system. For example, if the number of scratches is to be reduced sufficiently, there is a problem that productivity is impaired due to a decrease in the polishing rate.

  Accordingly, in one aspect, the present disclosure provides a polishing composition for a magnetic disk substrate that can reduce scratches without impairing productivity, and a method for manufacturing a magnetic disk substrate using the same.

In one aspect, the present invention provides (a) silica particles, (b) an acid, (c) an oxidizing agent, (d) an oxyalkylene alkyl ether sulfate compound represented by the following general formula (I), (e) An anionic polymer having at least one of a sulfonic acid group and a carboxylic acid group, and (f) a polishing composition for a magnetic disk substrate (hereinafter referred to as “a”) having a pH of less than 3.0 at 25 ° C. Also referred to as “polishing liquid composition according to the present disclosure”.
R-O- (EO) n- SO 3 M (I)
[In formula (I), R represents a linear or branched hydrocarbon group having 9 to 17 carbon atoms, and M represents hydrogen, an alkali metal, an ammonium ion, or an alkylammonium ion. EO represents an ethylene oxide group, and n represents a natural number of 2 or more and 4 or less. ]

  In another aspect, the present invention relates to a method for manufacturing a magnetic disk substrate including a step of polishing a substrate to be polished using the polishing composition for a magnetic disk substrate according to the present disclosure. In another aspect, the present invention relates to a magnetic disk substrate polishing method including a step of polishing a substrate to be polished using the magnetic disk substrate polishing liquid composition according to the present disclosure.

  In one embodiment, the present disclosure can exhibit an effect of reducing scratches on the surface of a substrate to be polished after polishing without impairing the polishing rate. In addition, in another aspect, the present disclosure can produce an effect that a magnetic disk substrate with reduced scratches and improved substrate surface quality, particularly a perpendicular magnetic recording type magnetic disk substrate, can be manufactured without impairing productivity. .

  In one aspect, the present disclosure provides, as an abrasive liquid composition for polishing a surface of a substrate to be polished for a magnetic disk, an oxyalkylene alkyl ether sulfate compound having a specific structure, and at least one of a sulfonic acid group and a carboxylic acid group. Based on the knowledge that the use of a polishing composition containing a combination with an anionic polymer can produce a magnetic disk substrate with a low number of scratches that can meet the demand for higher recording capacity and can maintain the polishing rate. .

  In the present disclosure, “scratch” is a fine scratch on a substrate surface having a depth of 1 nm or more, a width of 50 nm or more, and a length of 500 nm or more in one or a plurality of embodiments. It can be detected by a Candela 7100 series manufactured by KLA Tencor or NS1500 series manufactured by Hitachi High-Technology, and can be quantitatively evaluated as the number of scratches. Further, the size and shape of the detected scratch can be analyzed with an atomic force microscope (AFM), a scanning electron microscope (SEM), and a transmission electron microscope (TEM).

  Details of the mechanism by which the polishing composition according to the present disclosure can reduce scratches while maintaining productivity are not clear, but are considered as follows.

  In the oxyalkylene alkyl ether sulfate-based compound, it is considered that the alkyl portion is arranged and strongly adsorbed on the pad surface, suppresses friction between the polishing pad and the substrate to be polished, and reduces the number of scratches while reducing the polishing rate. Similarly, the anionic polymer having at least one of a sulfonic acid group and a carboxylic acid group also reduces the number of scratches by the hydrophobic unit adsorbing to the polishing pad and suppressing friction between the polishing pad and the substrate to be polished. However, since the pad surface is thickly covered, the polishing rate decreases.

  However, when the polishing composition according to the present disclosure in which an oxyalkylene alkyl ether sulfate-based compound is combined with an anionic polymer having at least one of a sulfonic acid group and a carboxylic acid group, the pH is less than 3.0. At first, the alkyl part of the oxyalkylene alkyl ether sulfate compound is first adsorbed and arranged on the surface of the pad. Similarly, the hydrophobic unit of an anionic polymer having at least one of sulfonic acid group and carboxylic acid group is adsorbed on the pad. By doing so, it is considered that the entire surface of the polishing pad is adsorbed without any gap, and the number of scratches is remarkably reduced. At the same time, an anionic polymer having at least one of a sulfonic acid group and a carboxylic acid group disturbs the adsorption sequence of the oxyalkylene alkyl ether sulfate compound, thereby weakening the strong adsorption to the pad, which is the cause of the polishing rate reduction. It is considered that productivity can be maintained while the number of scratches is significantly reduced. However, the present disclosure is not limited to this mechanism.

[Component (a): Silica particles]
The polishing liquid composition according to the present disclosure contains silica particles. Examples of the silica particles include, but are not limited to, colloidal silica, fumed silica, surface-modified silica, and the like in one or more embodiments. In one or more embodiments, the silica particles are preferably colloidal silica from the viewpoint of reducing scratches on the substrate after polishing. The colloidal silica may be composed of one type or a mixture of two or more types of colloidal silica.

  From the viewpoint of improving the polishing rate, the average particle size of the primary particles of silica is preferably 1 nm or more, more preferably 3 nm or more, still more preferably 5 nm or more, even more preferably 10 nm or more, even more preferably 20 nm or more, Further, from the viewpoint of reducing the surface roughness (centerline average roughness: Ra, Peak to Valley value: Rmax), it is preferably 40 nm or less, more preferably 35 nm or less, and even more preferably 30 nm or less. When primary particles are aggregated to form secondary particles, the average particle size of the secondary particles is preferably 1 nm or more, more preferably 5 nm or more, and even more preferably 10 nm, from the viewpoint of improving the polishing rate. From the viewpoint of reducing the surface roughness of the substrate, it is preferably 150 nm or less, more preferably 100 nm or less, still more preferably 80 nm or less, and even more preferably, 20 nm or more, even more preferably 25 nm or more. It is 50 nm or less, still more preferably 40 nm or less, and even more preferably 35 nm or less.

  Further, the average particle size of the primary particles of the silica is determined by using an image observed with a transmission electron microscope to obtain a particle size (D50) at which the cumulative volume frequency from the small particle size side of the primary particles becomes 50%. The value is the average particle size of the primary particles. The average particle diameter of the secondary particles can be measured as a volume average particle diameter using a laser light scattering method.

  As the particle size distribution of silica, from the viewpoint of improving the polishing rate, D90 / D50 is preferably 1.0 or more, more preferably 1.1 or more, preferably from the viewpoint of reducing the number of scratches and reducing the surface roughness. It is 5.0 or less, more preferably 3.0 or less, and still more preferably 2.00 or less. Note that D90 is a particle size at which the cumulative volume frequency from the small particle size side of the primary particles becomes 90% using an image observed with a transmission electron microscope.

  From the viewpoint of improving the polishing rate, the content of silica in the polishing composition according to the present disclosure is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and further preferably 1% by mass or more. From the viewpoint of reducing scratches, it is preferably 20% by mass or less, more preferably 15% by mass or less, still more preferably 13% by mass or less, and even more preferably 10% by mass or less. Even more preferably, it is 8% by mass or less.

[Component (b): Acid]
The polishing composition according to the present disclosure contains an acid. In the present disclosure, the use of an acid includes the use of an acid and / or a salt thereof. The acid used in the polishing composition according to the present disclosure is preferably a compound having a pK1 of 2 or less from the viewpoint of improving the polishing rate, and preferably pK1 from the viewpoint of reducing scratches on the substrate surface after polishing. Is 1.5 or less, more preferably 1 or less, and still more preferably a compound exhibiting strong acidity that cannot be expressed by pK1. Preferred acids are nitric acid, sulfuric acid, sulfurous acid, persulfuric acid, hydrochloric acid, perchloric acid, phosphoric acid, phosphonic acid, phosphinic acid, pyrophosphoric acid, tripolyphosphoric acid, amidosulfuric acid, 2-aminoethylphosphonic 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, ethane-1-hydroxy-1,1,2-triphosphonic acid, ethane-1,2-dicarboxy-1,2-diphosphonic acid, methanehydroxy Phosphonic acid, 2-phosphonobutane-1,2-dicarboxylic acid, 1-phosphonobutane-2,3,4 Organic phosphonic acids such as tricarboxylic acid and α-methylphosphonosuccinic acid, aminocarboxylic acids such as glutamic acid, picolinic acid and aspartic acid, carboxylic acids such as citric acid, tartaric acid, oxalic acid, nitroacetic acid, maleic acid and oxaloacetic acid Is mentioned. Among these, from the viewpoint of reducing scratches, inorganic acids, carboxylic acids, and organic phosphonic acids are preferable. From the viewpoints of improving the stability of the oxidizing agent and improving waste liquid treatment properties, inorganic acids and organic phosphonic acids are more preferable, and inorganic acids are more preferable. . Among inorganic acids, from the same viewpoint, nitric acid, sulfuric acid, hydrochloric acid, and perchloric acid are more preferable, phosphoric acid and sulfuric acid are more preferable, and sulfuric acid is even more preferable. Among the carboxylic acids, citric acid, tartaric acid, and maleic acid are more preferable, and citric acid is more preferable. Among organic phosphonic acids, 1-hydroxyethylidene-1,1-diphosphonic acid, aminotri (methylenephosphonic acid), ethylenediaminetetra (methylenephosphonic acid), diethylenetriaminepenta (methylenephosphonic acid), and salts thereof are more preferred. More preferred are -hydroxyethylidene-1,1-diphosphonic acid and aminotri (methylenephosphonic acid). These acids and salts thereof may be used alone or in admixture of two or more. Here, pK1 is a logarithmic value of the reciprocal of the first acid dissociation constant (25 ° C.) of the organic compound or inorganic compound. The pK1 of each compound is described in, for example, the revised 4th edition, Chemical Handbook (Basic Edition) II, pp316-325 (Edited by Chemical Society of Japan).

  The content of the acid and its salt in the polishing composition is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, and still more preferably 0.05% by mass from the viewpoint of improving the polishing rate. From the viewpoint of reducing the number of scratches, it is preferably 5.0% by mass or less, more preferably 4.0% by mass, more preferably 0.1% by mass or more, still more preferably 0.3% by mass or more. Hereinafter, it is more preferably 3.0% by mass or less, still more preferably 2.0% by mass or less, and still more preferably 1.0% by mass or less. In addition, the acid corresponding to the sulfonic acid as the surfactant used in the present disclosure is not included in the “acid” used in the polishing composition according to the present disclosure.

[Component (c): Oxidizing agent]
The polishing liquid composition concerning this indication contains an oxidizing agent. As an oxidizing agent that can be used in the polishing liquid composition according to the present disclosure, from the viewpoint of improving the polishing rate and reducing scratches on the substrate surface after polishing, peroxide, permanganic acid or a salt thereof, chromic acid or a salt thereof, Examples include peroxo acids or salts thereof, oxygen acids or salts thereof, metal salts, nitric acids, sulfuric acids, and the like.

  Examples of the peroxide include hydrogen peroxide, sodium peroxide, barium peroxide, etc., examples of the permanganic acid or salt thereof include potassium permanganate, and examples of the chromic acid or salt thereof include chromium. Acid metal salts, metal dichromates, and the like. Peroxo acids or salts thereof include peroxodisulfuric acid, ammonium peroxodisulfate, peroxodisulfate metal salts, peroxophosphoric acid, peroxosulfuric acid, sodium peroxoborate, and performic acid. Peroxyacetic acid, perbenzoic acid, perphthalic acid, etc., and oxygen acids or salts thereof include hypochlorous acid, hypobromite, hypoiodous acid, chloric acid, bromic acid, iodic acid, hypochlorous acid. Examples include sodium chlorate, calcium hypochlorite, and metal salts include iron (III) chloride, iron (III) nitrate, iron (III) sulfate, and iron citrate. III), ammonium iron (III), and the like.

  Preferable oxidizing agents from the viewpoint of reducing the number of scratches include hydrogen peroxide, iron (III) nitrate, peracetic acid, ammonium peroxodisulfate, iron (III) sulfate, and iron (III) ammonium sulfate. As a more preferable oxidizing agent, hydrogen peroxide is mentioned from the viewpoint that metal ions do not adhere to the surface and are generally used and inexpensive. These oxidizing agents may be used alone or in admixture of two or more.

  The content of the oxidizing agent in the polishing liquid composition is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and further preferably 0.1% by mass or more from the viewpoint of improving the polishing rate. From the viewpoint of reducing the number of scratches, it is preferably 4.0% by mass or less, more preferably 2.0% by mass or less, and further preferably 1.0% by mass or less.

[Component (d): Oxyalkylene alkyl ether sulfate compound]
The oxyalkylene alkyl ether sulfate-based compound used in the polishing liquid composition according to the present disclosure is represented by the following general formula (I).
R-O- (EO) n- SO 3 M (I)
[In Formula (I), R represents a linear or branched hydrocarbon group having 9 to 17 carbon atoms, and M represents hydrogen, an alkali metal, an ammonium ion, or an alkylammonium ion. EO represents an ethylene oxide group, and n represents a natural number of 2 or more and 4 or less. ]

  The added mole number n of ethylene oxide groups in the oxyalkylene alkyl ether sulfate-based compound is 2 or more and 4 or less, preferably 2 or more and 3 or less, more preferably 3 from the viewpoint of adsorptivity to the silica surface. .

  Examples of the counter ion of the oxyalkylene alkyl ether sulfate compound used in the polishing liquid composition according to the present disclosure include an organic cation such as a quaternary ammonium ion in addition to an inorganic cation such as an alkali metal ion or an animmonium ion. Is mentioned. From the viewpoint of solubility of sulfonate in water, alkali metal ions are preferable, and sodium ions are more preferable.

  R in the oxyalkylene alkyl ether sulfate-based compound is preferably a linear or branched alkyl group or alkenyl group from the viewpoint of improving the polishing rate and reducing scratches on the substrate surface after polishing. The carbon number of R is preferably 10 or more and 16 or less, more preferably 12 or more and 16 or less, still more preferably 14 or more and 16 or less, and even more preferably 16 from the viewpoint of improving the polishing rate and reducing scratches on the substrate surface after polishing. It is.

  The oxyalkylene alkyl ether sulfate-based compound used in the polishing composition according to the present disclosure may be used alone or in combination of two or more.

  The content of the oxyalkylene alkyl ether sulfate-based compound in the polishing composition is preferably 0.005% by mass or more, more preferably 0.010, from the viewpoint of improving the polishing rate and reducing scratches on the substrate surface after polishing. % By mass or more, more preferably 0.03% by mass or more, still more preferably 0.05% by mass or more, and even more preferably 0.08% by mass or more, from the viewpoint of reducing scratches on the substrate surface after polishing. And from the viewpoint of operability such as foaming resistance, preferably 2.0% by mass or less, more preferably 1.0% by mass or less, still more preferably 0.5% by mass or less, and even more preferably 0.3% by mass. Hereinafter, it is still more preferably 0.2% by mass or less. Further, from the viewpoint of improving the polishing rate, reducing scratches on the surface of the substrate after polishing, and from the viewpoint of operability such as foaming resistance, it is preferably 0.005 to 2.0 mass%, more preferably 0.005 to 1.0. % By weight, more preferably from 0.010 to 0.5% by weight, even more preferably from 0.010 to 0.3% by weight, even more preferably from 0.03 to 0.3% by weight, even more preferably from 0.001%. It is 05-0.2 mass%, More preferably, it is 0.08-0.2 mass%.

[Component (e): Anionic polymer having at least one of sulfonic acid group and carboxylic acid group]
The polishing composition according to the present disclosure contains an anionic polymer having at least one of a sulfonic acid group and a carboxylic acid group from the viewpoint of maintaining the polishing rate and reducing scratches. The anionic polymer having at least one of a sulfonic acid group and a carboxylic acid group in the present disclosure is preferably water-soluble. Here, “water-soluble” means that the solubility in 100 g of water at 20 ° C. is 2 g or more.

  The anionic polymer having at least one of a sulfonic acid group and a carboxylic acid group in the present disclosure is composed of one or more monomers of a monomer having a sulfonic acid group and a monomer having a carboxylic acid group as a constituent unit. It is preferable to include. An anionic polymer having at least one of a sulfonic acid group and a carboxylic acid group is obtained by polymerizing, for example, a monomer having a sulfonic acid group, a monomer having a carboxylic acid group, and, if necessary, other monomers. Can be obtained. The arrangement of these monomers may be random, block, or graft, but is preferably random from the viewpoint of maintaining the polishing rate and reducing scratches.

  The salt in the case where the anionic group is a salt is not particularly limited, and specific examples include salts with metals, ammonium, alkylammonium and the like. Specific examples of the metal include metals belonging to the periodic table (long-period type) 1A, 1B, 2A, 2B, 3A, 3B, 4A, 6A, 7A, or Group 8. Specific examples of alkylammonium include tetramethylammonium, tetraethylammonium, tetrabutylammonium and the like. Among these, when the anionic group is a salt, the salt with a metal belonging to Group 1A or ammonium is preferable, and the salt with ammonium, sodium or potassium is more preferable from the viewpoint of maintaining the polishing rate and reducing scratches. Sodium is more preferred.

  As a suitable example of the anionic polymer having at least one of a sulfonic acid group and a carboxylic acid group in the present disclosure, from the viewpoint of maintaining a polishing rate and reducing scratches, the monomer and carboxylic acid having a sulfonic acid group shown below are shown. A polymer containing a structural unit derived from a monomer having an acid group or a salt thereof is preferred.

  Specific examples of the monomer having a sulfonic acid group include isoprene sulfonic acid, 2- (meth) acrylamide-2-methylpropane sulfonic acid, styrene sulfonic acid, methallyl sulfonic acid, vinyl sulfonic acid, allyl sulfonic acid, iso Amylene sulfonic acid, naphthalene sulfonic acid and the like are mentioned, and 2- (meth) acrylamide-2-methylpropane sulfonic acid and styrene sulfonic acid are preferable from the viewpoint of maintaining the polishing rate and reducing scratches, and 2- (meth) acrylamide- 2-methylpropanesulfonic acid is more preferred. Examples of the monomer having a carboxylic acid group include itaconic acid, (meth) acrylic acid, and maleic acid. From the viewpoint of maintaining the polishing rate and reducing scratches, (meth) acrylic acid and maleic acid are preferable.

  Further, the anionic polymer having at least one of a sulfonic acid group and a carboxylic acid group in the present disclosure may contain a structural unit derived from a monomer other than the above. Examples of other monomers include aromatic vinyl compounds such as styrene, α-methylstyrene, vinyltoluene, and p-methylstyrene, methyl (meth) acrylate, ethyl (meth) acrylate, and (meth) acrylic acid. (Meth) acrylic acid alkyl esters such as octyl, aliphatic conjugated dienes such as butadiene, isoprene, 2-chloro-1,3-butadiene, 1-chloro-1,3-butadiene, and cyanation of (meth) acrylonitrile Examples thereof include vinyl compounds, and styrene and bisphenol are preferable from the viewpoint of ease of polymerization with a monomer having a sulfonic acid group and a monomer having a carboxylic acid group.

  In addition, as a suitable example of the anionic polymer having at least one of a sulfonic acid group and a carboxylic acid group in the present disclosure, the anionic polymer has a sulfonic acid group and an aromatic ring in each of the main chain and the side chain. Preferred are water-soluble polymers. It can be produced by polymerizing a compound having a sulfonic acid group and a compound capable of introducing an aromatic ring into both the main chain and side chain of the water-soluble polymer by a known means such as an addition condensation method in the presence of formaldehyde. Specifically, the compound currently disclosed by Unexamined-Japanese-Patent No. 2012-135863 is mentioned. From the viewpoint of improving the polishing rate and reducing scratches on the substrate surface after polishing, a formaldehyde addition condensate of bisphenol S and phenolsulfonic acid is preferred.

  Preferable specific examples of the anionic polymer having at least one of a sulfonic acid group and a carboxylic acid group in the present disclosure include (meth) acrylic acid / 2- (meth) acrylamide-2-methylpropanesulfonic acid copolymer, malee Examples include acid / styrene sulfonic acid copolymer, styrene / styrene sulfonic acid copolymer, bisphenol S / phenol sulfonic acid formaldehyde addition condensate, and polyacrylic acid. Another preferred specific example is sodium lignin sulfonate as a sulfonated polymer derived from a natural product. Among these, (meth) acrylic acid / 2- (meth) acrylamide-2-methylpropanesulfonic acid copolymer, maleic acid / styrenesulfonic acid copolymer, bisphenol S / Phenolsulfonic acid formaldehyde addition condensate and polyacrylic acid are preferable, (meth) acrylic acid / 2- (meth) acrylamide-2-methylpropanesulfonic acid copolymer, bisphenol S / phenolsulfonic acid formaldehyde addition condensate, polyacrylic An acid is more preferable, and a (meth) acrylic acid / 2- (meth) acrylamide-2-methylpropanesulfonic acid copolymer is more preferable.

[Weight average molecular weight of anionic polymer having at least one of sulfonic acid group and carboxylic acid group]
The weight average molecular weight of the anionic polymer having at least one of a sulfonic acid group and a carboxylic acid group is preferably 500 or more, more preferably 1000 or more, further preferably 1500 or more, from the viewpoint of reducing scratches on the substrate surface after polishing. Even more preferably, it is 5000 or more, and from the viewpoint of improving the polishing rate, it is preferably 120,000 or less, more preferably 100,000 or less, still more preferably 30,000 or less, and even more preferably 15,000 or less. The weight average molecular weight is a value measured by the method described in Examples using gel permeation chromatography (GPC).

  When the anionic polymer having at least one of a sulfonic acid group and a carboxylic acid group forms a salt at least partially, the counter ion is not particularly limited and is the same as in the case of the above-mentioned hydrophilic structural unit. And salts with metals, ammonium, alkylammonium and the like, and sodium ion is preferred.

  The content of the anionic polymer having at least one of a sulfonic acid group and a carboxylic acid group in the polishing composition is preferably 0.001% by mass or more, more preferably from the viewpoint of reducing scratches on the substrate surface after polishing. 0.005% by mass or more, more preferably 0.010% by mass or more, still more preferably 0.020% by mass or more, and even more preferably 0.030% by mass or more. From the viewpoint of improving the polishing rate, preferably 1.0% by mass or less, more preferably 0.10% by mass or less, further preferably 0.080% by mass or less, still more preferably 0.060% by mass or less, and still more preferably 0.050% by mass or less. .

  In the polishing composition according to the present disclosure, the content ratio of the component (d) oxyalkylene alkyl ether sulfate compound and the component (e) an anionic polymer having at least one of a sulfonic acid group and a carboxylic acid group [ (D) (mass%) / (e) (mass%)] is preferably 0.05 or more, more preferably 0.10 or more, and further preferably 0.30 or more, from the viewpoint of maintaining the polishing rate and reducing scratches. Even more preferably, it is 0.50 or more, and even more preferably 1.0 or more. From the same viewpoint, the content ratio [(d) (mass%) / (e) (mass%)] is preferably 15 or less, more preferably 12 or less, still more preferably 10 or less, and even more preferably 5. 0 or less. In addition, the content ratio of the component (d) oxyalkylene alkyl ether sulfate compound and the component (e) an anionic polymer having at least one of a sulfonic acid group and a carboxylic acid group [(d) (mass%) / (E) (mass%)] is preferably 0.05 or more and 15 or less, more preferably 0.10 or more and 12 or less, and still more preferably 0.00 from the viewpoint of maintaining the polishing rate and reducing scratches on the substrate surface after polishing. It is 10 or more and 10 or less, more preferably 0.30 or more and 10 or less, still more preferably 0.50 or more and 5 or less, and still more preferably 1.0 or more and 5 or less.

[Component (f): Water]
Water in the polishing composition according to the present disclosure is used as a medium, and examples thereof include distilled water, ion exchange water, and ultrapure water. From the viewpoint of the surface cleanliness of the substrate to be polished, ion exchange water and ultrapure water are preferable, and ultrapure water is more preferable. The water content in the polishing composition is preferably 60% by mass or more, more preferably 70% by mass or more from the viewpoint of economy, and preferably 99.9% by mass from the viewpoint of reducing the number of scratches and improving the polishing rate. % Or less, more preferably 98.9% by mass or less. Moreover, you may mix | blend organic solvents, such as alcohol, in the range which does not inhibit the effect in this indication.

[Component (g): Aliphatic amine compound or alicyclic amine compound]
The polishing composition according to the present disclosure preferably contains an aliphatic amine compound or an alicyclic amine compound from the viewpoint of maintaining the polishing rate and reducing scratches. The aliphatic amine compound or alicyclic amine compound that can be contained in the polishing liquid composition according to the present disclosure has 2 or more nitrogen atoms in the molecule from the viewpoint of reducing the number of scratches on the substrate surface after polishing. The aliphatic amine compound or alicyclic amine compound has 4 or less nitrogen atoms, preferably 3 or less, and more preferably 2 or less from the viewpoint of maintaining the polishing rate. Therefore, the aliphatic amine compound or alicyclic amine compound has 2 to 4 nitrogen atoms, preferably 2 to 3 in terms of maintaining the polishing rate and reducing the number of scratches. More preferably.

  The aliphatic amine compound used in the polishing liquid composition according to the present disclosure includes ethylenediamine, N, N, N ′, N′-tetramethylethylenediamine, 1 from the viewpoint of improving the polishing rate and reducing scratches on the substrate surface after polishing. , 2-diaminopropane, 1,3-diaminopropane, 1,4-diaminobutane, hexamethylenediamine, 3- (diethylamino) propylamine, 3- (dibutylamino) propylamine, 3- (methylamino) propylamine, Preferably selected from the group consisting of 3- (dimethylamino) propylamine, N-aminoethylethanolamine, N-aminoethylisopropanolamine, N-aminoethyl-N-methylethanolamine, diethylenetriamine, and triethylenetetramine. , Ethylenediamine, N N, N ′, N′-tetramethylethylenediamine, 1,2-diaminopropane, 1,3-diaminopropane, 1,4-diaminobutane, hexamethylenediamine, 3- (diethylamino) propylamine, 3- (dibutylamino ) Propylamine, 3- (methylamino) propylamine, 3- (dimethylamino) propylamine, N-aminoethylethanolamine, N-aminoethylisopropanolamine, and N-aminoethyl-N-methylethanolamine Is more preferably selected from N-aminoethylethanolamine.

  The alicyclic amine compound used in the polishing liquid composition according to the present disclosure includes piperazine, 2-methylpiperazine, 2,5-dimethylpiperazine, 1-, from the viewpoint of improving the polishing rate and reducing scratches on the substrate surface after polishing. Preferably selected from the group consisting of amino-4-methylpiperazine, N-methylpiperazine, 1- (2-aminoethyl) piperazine, and hydroxyethylpiperazine, piperazine, 2-methylpiperazine, 2,5-dimethylpiperazine More preferably, it is selected from the group consisting of N-methylpiperazine and hydroxyethylpiperazine, more preferably hydroxyethylpiperazine.

  The content of the aliphatic amine compound or the alicyclic amine compound in the polishing liquid composition according to the present disclosure is preferably 0.00 with respect to the mass of the entire polishing liquid composition from the viewpoint of reducing scratches on the substrate surface after polishing. 001% by mass or more, more preferably 0.003% by mass or more, further preferably 0.010% by mass or more, still more preferably 0.030% by mass or more, and preferably 1 from the viewpoint of improving the polishing rate. It is 0.0 mass% or less, More preferably, it is 0.50 mass% or less, More preferably, it is 0.10 mass% or less, More preferably, it is 0.08 mass% or less, More preferably, it is 0.070 mass% or less. In addition, the aliphatic amine compound in polishing liquid composition may be one type, and may be two or more types.

  Further, the content ratio [(d) (mass%) of the component (d) oxyalkylene alkyl ether sulfate-based compound and the component (g) aliphatic amine compound or alicyclic amine compound in the polishing composition. ) / (G) (mass%)] is preferably 0.01 or more, more preferably 0.05 or more, still more preferably 0.10 or more, and even more preferably 0, from the viewpoint of maintaining the polishing rate and reducing scratches. .25 or more, even more preferably 0.50 or more, and from the same viewpoint, it is preferably 20 or less, more preferably 15 or less, still more preferably 10 or less, even more preferably 5.0 or less, and even more preferably 3 0.0 or less. Further, the content ratio [(d) (mass%) of the component (d) oxyalkylene alkyl ether sulfate-based compound and the component (g) aliphatic amine compound or alicyclic amine compound in the polishing composition. ) / (G) (mass%)] is preferably from 0.01 to 20, more preferably from 0.05 to 20, and even more preferably from the viewpoint of maintaining the polishing rate and reducing scratches on the substrate surface after polishing. 10-15, even more preferably 0.10-10, even more preferably 0.25-5, even more preferably 0.25-3, even more preferably 0.50-3.

[Component (h): Heteroaromatic compound]
The polishing composition according to the present disclosure preferably contains a heterocyclic aromatic compound from the viewpoint of improving the polishing rate and reducing scratches on the substrate surface after polishing. The heterocyclic aromatic compound that can be contained in the polishing liquid composition according to the present disclosure is a heterocyclic aromatic compound containing two or more nitrogen atoms in the heterocyclic ring from the viewpoint of improving the polishing rate and reducing scratches on the substrate surface after polishing. It is a compound and preferably has 3 or more nitrogen atoms in the heterocyclic ring, more preferably 3 or more and 9 or less, still more preferably 3 or more and 5 or less, and even more preferably 3 or 4.

  From the viewpoint of reducing scratches on the substrate surface after polishing, the heterocyclic aromatic compound contained in the polishing liquid composition according to the present disclosure has a low pKa of the protonated heteroaromatic compound, that is, electrophilicity. In particular, the pKa is preferably −3 to 4, more preferably −3 to 3, and still more preferably −3 to 2.5. Heterocyclic aromatic compounds containing two or more nitrogen atoms in the heterocyclic ring include pyrimidine, pyrazine, pyridazine, 1,2,3-triazine, 1,2,4-triazine, 1,2,5-triazine, 1 , 3,5-triazine, 1,2,4-oxadiazole, 1,2,5-oxadiazole, 1,3,4-oxadiazole, 1,2,5-thiadiazole, 1,3,4 -Thiadiazole, 3-aminopyrazole, 4-aminopyrazole, 3,5-dimethylpyrazole, pyrazole, 2-aminoimidazole, 4-aminoimidazole, 5-aminoimidazole, 2-methylimidazole, 2-ethylimidazole, imidazole, benzo Imidazole, 1,2,3-triazole, 4-amino-1,2,3-triazole, 5-amino-1,2,3-tri Sol, 1,2,4-triazole, 3-amino-1,2,4-triazole, 5-amino-1,2,4-triazole, 3-mercapto-1,2,4-triazole, 1H-tetrazole, 5- Aminotetrazole, 1H-benzotriazole, 1H-tolyltriazole, 2-aminobenzotriazole, 3-aminobenzotriazole, or these alkyl or amine substituents are preferred, and 1H-tetrazole, 1H-benzotriazole, 1H- Toryltriazole is more preferable, 1H-tetrazole, 1H-benzotriazole is more preferable, and 1H-benzotriazole is still more preferable. Examples of the alkyl group of the alkyl-substituted product include a lower alkyl group having 1 to 4 carbon atoms, and more specifically, a methyl group and an ethyl group. Examples of the amine-substituted product include 1- [N, N-bis (hydroxyethylene) aminomethyl] benzotriazole and 1- [N, N-bis (hydroxyethylene) aminomethyl] tolyltriazole. The pKa of the protonated heterocyclic aromatic compound is described in, for example, “Aromatic Heterocyclic Compound Chemistry” (Nao Sakamoto, Kodansha Scientific).

  The content of the heterocyclic aromatic compound in the polishing liquid composition according to the present disclosure is preferably 0.01% by mass or more, more preferably 0%, based on the total mass of the polishing liquid composition, from the viewpoint of reducing the number of scratches. 0.05% by mass or more, more preferably 0.1% by mass or more, and preferably 3.0% by mass or less, more preferably 1.0% by mass or less, and further preferably 0.8% by mass from the viewpoint of improving the polishing rate. % Or less, still more preferably 0.5% by mass or less. In addition, the heterocyclic aromatic compound in the polishing composition may be one kind or two or more kinds.

[Other ingredients]
In the polishing liquid composition according to the present disclosure, other components can be blended as necessary. Examples of other components include thickeners, dispersants, rust inhibitors, and basic substances. The content of these other optional components in the polishing composition may be in a range that does not interfere with the effects of the present disclosure, but is preferably 0% by mass or more from the viewpoint of reducing scratches and improving the polishing rate. In view of the above, it is preferably 10% by mass or less, more preferably 5% by mass or less. However, the polishing composition according to the present disclosure can exhibit the effect of reducing scratches on the substrate surface after polishing without including other components.

  In addition, it is preferable that the polishing liquid composition concerning this indication does not contain an alumina abrasive grain. In the present disclosure, “not containing alumina abrasive grains” means that, in one or a plurality of embodiments, it does not contain alumina particles, does not substantially contain alumina particles, and contains alumina particles in an amount that functions as abrasive grains. The absence of an amount of alumina particles that affect the polishing results. The specific content of alumina particles is not particularly limited, but is preferably 5% by mass or less, more preferably 2% by mass or less, still more preferably 1% by mass or less, and substantially 0%. Is even more preferred.

[PH of polishing composition]
The pH of the polishing composition according to the present disclosure is less than 3.0 from the viewpoint of reducing scratches and improving the polishing rate, preferably 2.5 or less, more preferably 2.0 or less, and still more preferably 1. 5 or less. Further, from the viewpoint of securing the machining allowance and reducing scratches on the substrate surface after polishing, 0.5 or more is preferable, more preferably 0.8 or more, still more preferably 1.0 or more, and even more preferably 1.2. That's it. In addition, said pH is pH of polishing liquid composition in 25 degreeC, can be measured using a pH meter, and is a numerical value 40 minutes after immersion of an electrode.

[Method for preparing polishing liquid composition]
The polishing composition according to the present disclosure includes, for example, silica particles, an acid, an oxidizing agent, an oxyalkylene alkyl ether sulfate-based compound, an anionic polymer having at least one of a sulfonic acid group and a carboxylic acid group, water, and It can prepare by mixing by a well-known method including components, such as an aliphatic amine compound and a heterocyclic aromatic compound, as needed. At this time, the silica particles may be mixed in a concentrated slurry state, or may be mixed after being diluted with water or the like. The content and concentration of each component in the polishing liquid composition according to the present disclosure are in the above-described ranges, but as another aspect, the polishing liquid composition according to the present disclosure may be prepared as a concentrate. The concentration factor is preferably 20 times or less, preferably 10 times or less, and more preferably 2 times or more, from the viewpoints of storage stability, operability, and transportability.

[Polished substrate]
The substrate to be polished by the polishing composition according to the present disclosure is an aluminum alloy substrate plated with Ni—P. By using the polishing composition according to the present disclosure for polishing an Ni-P plated aluminum alloy substrate, the number of scratches on the surface of the substrate after polishing is reduced, and productivity maintenance that is an effect that exceeds the conventional prediction is achieved. There is an effect. In the present disclosure, “Ni—P plated aluminum alloy substrate” refers to a surface of an aluminum alloy plate material for a magnetic disk substrate that has been subjected to electroless Ni—P plating after being ground. A magnetic disk substrate can be manufactured by polishing the surface of the Ni-P plated aluminum alloy substrate and forming a magnetic film on the substrate surface by sputtering or the like. There is no restriction | limiting in particular in the shape of the said to-be-polished substrate, For example, what is necessary is just the shape which has planar parts, such as a disk shape, plate shape, slab shape, prism shape, and the shape which has curved surface parts, such as a lens. Of these, a disk-shaped substrate to be polished is suitable. In the case of a disk-shaped substrate to be polished, the outer diameter is, for example, about 2 to 95 mm, and the thickness is, for example, about 0.5 to 2 mm.

[Method of manufacturing magnetic disk substrate]
As another aspect, the present disclosure relates to a method for manufacturing a magnetic disk substrate (hereinafter also referred to as a manufacturing method according to the present disclosure). The manufacturing method according to the present disclosure includes a step of polishing a substrate to be polished using the above-described polishing liquid composition according to the present disclosure (hereinafter also referred to as a polishing step using the polishing liquid composition according to the present disclosure). This is a method of manufacturing a magnetic disk substrate. Thus, a magnetic disk substrate with reduced scratches on the polished substrate surface can be provided without impairing productivity. The manufacturing method according to the present disclosure is particularly suitable for a method of manufacturing a magnetic disk substrate for perpendicular magnetic recording. Therefore, the manufacturing method according to the present disclosure is a method for manufacturing a magnetic disk substrate for a perpendicular magnetic recording system, which includes a polishing step using the polishing composition according to the present disclosure as another aspect.

  As a specific example of a method for polishing a substrate to be polished using the polishing composition according to the present disclosure, the substrate to be polished is sandwiched between a surface plate to which a polishing pad such as a non-woven organic polymer polishing cloth is attached, Examples include a method of polishing the substrate to be polished by moving the surface plate and / or the substrate to be polished while supplying the polishing composition according to the present disclosure to a polishing machine.

  When the polishing process of the substrate to be polished is performed in multiple stages, the polishing process using the polishing composition according to the present disclosure is preferably performed in the second stage or more, and more preferably performed in the final polishing process. . At that time, in order to avoid mixing of the polishing agent and polishing liquid composition in the previous step, different polishing machines may be used, and when different polishing machines are used, polishing is performed for each polishing process. It is preferable to clean the substrate. The polishing machine is not particularly limited, and a known polishing machine for polishing a magnetic disk substrate can be used.

[Polishing pad]
The polishing pad used in the production method according to the present disclosure is not particularly limited, and a polishing pad of a suede type, a nonwoven fabric type, a polyurethane closed-cell foam type, or a two-layer type in which these are laminated can be used. From the viewpoint of polishing rate, a suede type polishing pad is preferable.

  The average hole diameter of the surface member of the polishing pad is preferably 50 μm or less, more preferably 45 μm or less, still more preferably 40 μm or less, and even more preferably 35 μm or less, from the viewpoint of scratch reduction and pad life. On the other hand, from the viewpoint of holding the polishing liquid of the pad, the average pore diameter is preferably 0.01 μm or more, more preferably 0.1 μm or more, and still more preferably in order to keep the polishing liquid in the pores and prevent the liquid from running out. Is 1 μm or more, and more preferably 10 μm or more. Further, the maximum value of the opening diameter of the polishing pad is preferably 100 μm or less, more preferably 70 μm or less, still more preferably 60 μm or less, and even more preferably 50 μm or less from the viewpoint of maintaining the polishing rate.

[Polishing load]
The polishing load in the polishing step using the polishing composition according to the present disclosure is preferably 3.0 kPa or more, more preferably 5.0 kPa or more, and even more preferably 6.0 kPa or more, from the viewpoint of improving the polishing rate. Further, from the viewpoint of reducing scratches on the substrate surface after polishing, it is preferably 20 kPa or less, more preferably 15 kPa or less, still more preferably 10 kPa or less, and even more preferably 8 kPa or less. In the manufacturing method according to the present disclosure, the polishing load refers to the pressure of the surface plate applied to the polishing surface of the substrate to be polished during polishing. The polishing load can be adjusted by applying air pressure or weight to at least one of the surface plate and the substrate to be polished.

[Supply of polishing liquid composition]
The supply rate of the polishing liquid composition according to the present disclosure in the polishing step using the polishing liquid composition according to the present disclosure is preferably 0.025 mL / min or more per 1 cm ^{2 of the} substrate to be polished from the viewpoint of reducing the number of scratches. More preferably, it is 0.04 mL / min or more, more preferably 0.06 mL / min or more, and from the viewpoint of economy, it is preferably 15 mL / min or less, more preferably 10 mL / min or less, and even more preferably 1 mL / min. Min or less, even more preferably 0.5 mL / min or less, even more preferably 0.2 mL / min or less, and even more preferably 0.1 mL / min or less.

  Examples of a method of supplying the polishing composition according to the present disclosure to a polishing machine include a method of continuously supplying using a pump or the like. When supplying the polishing composition to the polishing machine, in addition to the method of supplying one component containing all the components, considering the stability of the polishing composition, etc., it is divided into a plurality of compounding component liquids, Two or more liquids can be supplied. In the latter case, for example, the plurality of compounding component liquids are mixed in the supply pipe or on the substrate to be polished to obtain the polishing liquid composition according to the present disclosure.

[Polishing method]
As another aspect, the present disclosure relates to a method for polishing a substrate to be polished, including polishing the substrate to be polished while bringing the polishing composition according to the present disclosure described above into contact with a polishing pad. By using the polishing method of this embodiment, a magnetic disk substrate with reduced scratches on the surface of the substrate after polishing, particularly a perpendicular magnetic recording type magnetic disk substrate, can be provided without impairing productivity. Examples of the substrate to be polished in the polishing method of this aspect include those used for the manufacture of magnetic disk substrates and magnetic recording medium substrates, as mentioned above. A substrate used for production is preferred. The specific polishing method and conditions can be the same as those in the manufacturing method according to the present disclosure described above.

  Regarding the above-described embodiment, the present disclosure further discloses the following composition, production method, or application.

<1> (a) silica particles, (b) acid, (c) oxidizing agent, (d) oxyalkylene alkyl ether sulfate compound represented by the following general formula (I), (e) sulfonic acid group and carvone A polishing composition for a magnetic disk substrate, comprising an anionic polymer having at least one of acid groups, and (f) water, wherein the pH at 25 ° C. is less than 3.0.
R-O- (EO) n- SO 3 M (I)
[In formula (I), R represents a linear or branched hydrocarbon group having 9 to 17 carbon atoms, and M represents hydrogen, an alkali metal, an ammonium ion, or an alkylammonium ion. EO represents an ethylene oxide group, and n represents a natural number of 2 or more and 4 or less. ]

<2> The average particle size of the primary particles of the silica particles is preferably 1 nm or more, more preferably 3 nm or more, still more preferably 5 nm or more, even more preferably 10 nm or more, even more preferably 20 nm or more, and / or Preferably, it is 40 nm or less, More preferably, it is 35 nm or less, More preferably, it is 30 nm or less, The polishing liquid composition for magnetic disk substrates as described in <1>.
<3> The average particle size of the secondary particles of the silica particles is preferably 1 nm or more, more preferably 5 nm or more, still more preferably 10 nm or more, even more preferably 20 nm or more, and even more preferably 25 nm or more, and / Or preferably 150 nm or less, more preferably 100 nm or less, still more preferably 80 nm or less, even more preferably 50 nm or less, even more preferably 40 nm or less, and even more preferably 35 nm or less, in <1> or <2> The polishing liquid composition for magnetic disk substrates as described.
<4> D90 / D50 of the particle size distribution of the silica particles is preferably 1.0 or more, more preferably 1.1 or more, and / or preferably 5.0 or less, more preferably 3.0 or less. The polishing composition for a magnetic disk substrate according to any one of <1> to <3>, more preferably 2.00 or less.
<5> The content of silica in the polishing composition is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, still more preferably 1% by mass or more, and even more preferably 3% by mass or more. And / or preferably 20% by weight or less, more preferably 15% by weight or less, still more preferably 13% by weight or less, even more preferably 10% by weight or less, and even more preferably 8% by weight or less. The polishing composition for a magnetic disk substrate according to any one of <1> to <4>.
<6> The content of the acid and its salt in the polishing composition is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, still more preferably 0.05% by mass or more, and even more. Preferably it is 0.1% by weight or more, even more preferably 0.3% by weight or more, and / or preferably 5.0% by weight or less, more preferably 4.0% by weight or less, still more preferably 3. The polishing composition for a magnetic disk substrate according to any one of <1> to <5>, which is 0% by mass or less, more preferably 2.0% by mass or less, and still more preferably 1.0% by mass or less. .
<7> The content of the oxidizing agent in the polishing composition is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, still more preferably 0.1% by mass or more, and / or Alternatively, it is preferably 4.0% by mass or less, more preferably 2.0% by mass or less, and further preferably 1.0% by mass or less, for the magnetic disk substrate according to any one of <1> to <6>. Polishing liquid composition.
<8> The content of the oxyalkylene alkyl ether sulfate-based compound in the polishing composition is preferably 0.005% by mass or more, more preferably 0.010% by mass or more, and further preferably 0.03% by mass. Or more, more preferably 0.05% by mass or more, still more preferably 0.08% by mass or more, and / or preferably 2.0% by mass or less, more preferably 1.0% by mass or less. More preferably 0.5% by mass or less, still more preferably 0.3% by mass or less, still more preferably 0.2% by mass or less, or preferably 0.005% by mass or more and 2.0% by mass. Or less, more preferably 0.005% by mass or more and 1.0% by mass or less, further preferably 0.010% by mass or more and 0.5% by mass or less, and even more preferably 0.010% by mass or less. 0.3% by mass or less, still more preferably 0.03% by mass or more and 0.3% by mass or less, still more preferably 0.05% by mass or more and 0.2% by mass or less, and even more preferably 0.08% by mass. The polishing composition for a magnetic disk substrate according to any one of <1> to <7>, wherein the polishing composition is from 1% to 0.2% by mass.
<9> An anionic polymer having at least one of a sulfonic acid group and a carboxylic acid group is a (meth) acrylic acid / 2- (meth) acrylamide-2-methylpropanesulfonic acid copolymer, bisphenol S / phenolsulfonic acid The polishing composition for a magnetic disk substrate according to any one of <1> to <8>, which is a formaldehyde addition condensate or polyacrylic acid.
<10> The content of the anionic polymer having at least one of a sulfonic acid group and a carboxylic acid group in the polishing liquid composition is preferably 0.001% by mass or more, more preferably 0.005% by mass or more, and still more preferably. Is 0.010% by mass or more, still more preferably 0.020% by mass or more, still more preferably 0.030% by mass or more, and / or preferably 1.0% by mass or less, more preferably 0.0. <1> to <9>, which is 10% by mass or less, more preferably 0.080% by mass or less, still more preferably 0.060% by mass or less, and still more preferably 0.050% by mass or less. The polishing liquid composition for magnetic disk substrates as described.
<11> Content ratio of the component (d) oxyalkylene alkyl ether sulfate compound and the component (e) an anionic polymer having at least one of a sulfonic acid group and a carboxylic acid group [(d) (mass%) / (E) (mass%)] is preferably 0.05 or more, more preferably 0.10 or more, still more preferably 0.30 or more, still more preferably 0.50 or more, and even more preferably 1.0. And / or, preferably 15 or less, more preferably 12 or less, even more preferably 10 or less, even more preferably 5.0 or less, or preferably 0.05 or more and 15 or less, more preferably 0.10 or more and 12 or less, more preferably 0.10 or more and 10 or less, still more preferably 0.30 or more and 10 or less, and even more preferably 0.50 or more and 5 or less. The polishing composition for a magnetic disk substrate according to any one of <1> to <10>, which is still more preferably 1.0 or more and 5 or less.
<12> The polishing composition for a magnetic disk substrate according to any one of <1> to <11>, for polishing an aluminum alloy substrate plated with Ni—P.
<13> The polishing composition for a magnetic disk substrate according to any one of <1> to <12>, further comprising a component (g) an aliphatic amine compound or an alicyclic amine compound.
<14> The content of the aliphatic amine compound or the alicyclic amine compound in the polishing composition is preferably 0.001% by mass or more, more preferably 0.003% by mass with respect to the total mass of the polishing composition. Or more, more preferably 0.010% by mass or more, even more preferably 0.030% by mass or more, and / or preferably 1.0% by mass or less, more preferably 0.50% by mass or less, still more preferably The polishing composition for magnetic disk substrates according to <13>, wherein is 0.10% by mass or less, more preferably 0.08% by mass or less, and still more preferably 0.070% by mass or less.
<15> Content ratio [(d) (mass) of the component (d) oxyalkylene alkyl ether sulfate compound and the component (g) aliphatic amine compound or alicyclic amine compound in the polishing composition. %) / (G) (mass%)] is preferably 0.01 or more, more preferably 0.05 or more, still more preferably 0.10 or more, even more preferably 0.25 or more, and even more preferably 0. .50 and / or, preferably 20 or less, more preferably 15 or less, even more preferably 10 or less, even more preferably 5.0 or less, even more preferably 3.0 or less, or preferably Is 0.01 or more and 20 or less, more preferably 0.05 or more and 20 or less, further preferably 0.10 or more and 15 or less, and even more preferably 0.10 or more and 10 or less. More preferably 0.25 or more and 5 or less, even more preferably 0.25 or more and 3 or less, and even more preferably 0.50 or more and 3 or less, polishing for a magnetic disk substrate according to <13> or <14> Liquid composition.
<16> The polishing composition for a magnetic disk substrate according to any one of <1> to <15>, further comprising a component (h) a heteroaromatic compound.
<17> The content of the heterocyclic aromatic compound in the polishing composition is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, still more preferably 0.1% by mass or more, and / Or preferably 3.0% by mass or less, more preferably 1.0% by mass or less, further preferably 0.8% by mass or less, and still more preferably 0.5% by mass or less, according to <16>. Polishing liquid composition for magnetic disk substrates.
<18> The pH of the polishing composition is preferably 2.5 or less, more preferably 2.0 or less, still more preferably 1.5 or less, and / or 0.5 or more, more preferably The polishing composition for a magnetic disk substrate according to any one of <1> to <17>, which is 0.8 or more, more preferably 1.0 or more, and even more preferably 1.2 or more.
<19> A method for producing a magnetic disk substrate, comprising a step of polishing a substrate to be polished using the polishing composition for a magnetic disk substrate according to any one of <1> to <18>.
<20> A method for polishing a magnetic disk substrate, comprising a step of polishing a substrate to be polished using the polishing composition for a magnetic disk substrate according to any one of <1> to <18>.

[ Reference Examples 1 to 6 and Comparative Examples 1 to 10]
The polishing liquid compositions of Reference Examples 1 to 6 and Comparative Examples 1 to 10 were prepared to polish the substrate to be polished, and scratches on the substrate after polishing were evaluated. The evaluation results are shown in Table 1 below. The used oxylalkylene alkyl ether sulfate, anionic polymer having at least one of sulfonic acid group and carboxylic acid group, preparation method of polishing liquid composition, measurement method of each parameter, polishing condition (polishing method) and evaluation method are as follows: It is as follows.

[Component (a): Colloidal silica]
As the colloidal silica, one having an average primary particle size of 24 nm, an average secondary particle size of 32 nm, and D90 / D50 of 1.16 (manufactured by JGC Catalysts & Chemicals) was used.

[Component (d): Oxyalkylene alkyl ether sulfate compound]
In Reference Examples 1 to 6, an alkyl group having 12 carbon atoms, an ethylene oxide group of 3 and a sodium salt C ₁₂ —O (EO) ₃ SO ₃ Na (Emar 20C, manufactured by Kao Corporation) were used.

[Component (e): Anionic polymer having at least one of sulfonic acid group and carboxylic acid group]
The anionic polymer having at least one of a sulfonic acid group and a carboxylic acid group used in the polishing liquid composition is the following five types of AA / AMPS, BisS / PhS, PAA, MA / SS, Lig and St / SS. . St / SS was manufactured by the following method. Moreover, the weight average molecular weight of these polymers was measured on condition of the following.
<Anionic polymer having at least one of sulfonic acid group and carboxylic acid group>
AA / AMPS: acrylic acid / acrylamido-2-methylpropanesulfonic acid copolymer sodium salt (molar ratio 80/20, weight average molecular weight 10,000, manufactured by Toagosei Co., Ltd.)
BisS / PhS: Sodium salt of bisphenol S / phenolsulfonic acid formaldehyde addition condensate (weight average molecular weight 5,000, manufactured by Konishi Chemical Co., Ltd.)
PAA: sodium polyacrylate (weight average molecular weight 10,000, manufactured by Wako Pure Chemical Industries, Ltd.)
MA / SS: maleic acid / styrene sulfonic acid (weight average molecular weight 5,000, VERSA-TL YE-920, manufactured by Akzo Nobel)
St / SS: Sodium salt of styrene / styrene sulfonic acid copolymer (molar ratio 33/67, weight average molecular weight 10,000, produced by the following method)
Lig: High purity high molecular weight sodium lignin sulfonate (Pearl Rex NP, manufactured by Nippon Paper Chemicals)
<Anionic polymer used in comparative example>
PAM: Polyacrylamide (weight average molecular weight 10,000, manufactured by Wako Pure Chemical Industries, Ltd.)
PVA: Polyvinyl alcohol (weight average molecular weight 22,000, manufactured by Wako Pure Chemical Industries, Ltd.)

[Method for producing sodium salt of styrene / styrene sulfonic acid copolymer]
Into a 1 L four-necked flask, 180 g of isopropyl alcohol (manufactured by Kishida Chemical), 270 g of ion-exchanged water, 10 g of styrene (manufactured by Kishida Chemical), and 40 g of sodium styrenesulfonate (manufactured by Wako Pure Chemical Industries) were charged. Using 7.2 g of azobis (2-methylpropionamidine) dihydrochloride (V-50, manufactured by Wako Pure Chemical Industries, Ltd.) as a reaction initiator, the polymerization was carried out dropwise at 83 ± 2 ° C. for 2 hours, followed by further aging for 2 hours. The solvent was removed under reduced pressure to obtain a white powdery styrene / styrenesulfonic acid copolymer sodium salt polymer.

[Method for measuring weight average molecular weight of polymer]
The weight average molecular weight of the polymer was measured by a gel permeation chromatography (GPC) method under the following measurement conditions.
[GPC conditions for AA / AMPS, MA / SS]
Column: TSKgel G4000PWXL + TSKgel G2500PWXL
(Tosoh product)
Guard column: TSK guard column PWXL (manufactured by Tosoh Corporation)
Eluent: 0.2M phosphate buffer / CH3CN = 9/1 (volume ratio)
Temperature: 40 ° C
Flow rate: 1.0 mL / min
Sample size: 5 mg / mL
Detector: RI
Conversion standard: Polyacrylic acid Na (Molecular weight (Mp): 115,000, 288,000, 4100, 1250 (manufactured by Soka Kagaku and American Polymer Standards Corp.))
[GPC conditions for St / SS]
Column: TSKgel α-M + TSKgel α-M (manufactured by Tosoh Corporation)
Guard column: TSK guard column α (Tosoh)
Eluent: 60 mmol / L phosphoric acid, 50 mmol / L LiBr / DMF
Temperature: 40 ° C
Flow rate: 1.0 mL / min
Sample size: 5 mg / mL
Detector: RI
Conversion standard: Polystyrene (Molecular weight (Mw): 590, 3600, 30,000, 96,000, 929,000, 842,000 (manufactured by Tosoh, Nishio Kogyo, and Chemco))
[GPC conditions for BisS / PhS]
Column: TSKgel GMPWXL + TSKgel GMPWXL (Tosoh Corporation)
Eluent: 0.2M phosphate buffer / CH ₃ CN = 7/3 (volume ratio)
Temperature: 40 ° C
Flow rate: 1.0 ml / min
Sample size: 2 mg / ml
Detector: RI
Standard substance: Sodium polystyrene sulfonate (weight average molecular weight: 1,100, 3,610, 14,900, 152,000, manufactured by POLMER STANDARDS SERVICE)

[Method for preparing polishing liquid composition]
Polishing liquid compositions of Reference Examples 1 to 6 and Comparative Examples 1 to 10 using the colloidal silica, the anionic polymer, the oxyalkylene alkyl ether sulfate compound, an acid (sulfuric acid), and an oxidizing agent (hydrogen peroxide) Was prepared. The colloidal silica concentration was 5% by mass, the sulfuric acid concentration was 0.5% by mass, and the hydrogen peroxide concentration was 0.5% by mass. The pH of the polishing composition was adjusted to 1.3 using sulfuric acid. In addition, said pH is a pH of polishing liquid composition in 25 degreeC, and is a numerical value 40 minutes after immersion of an electrode using pH meter "HM-30G" (made by Toa Denpa Kogyo Co., Ltd.) (below) The same).

[Polishing]
Using the polishing liquid compositions of Reference Examples 1 to 6 and Comparative Examples 1 to 10 prepared as described above, the following substrate to be polished was polished under the following polishing conditions. After polishing, the substrate was immersed in ion exchange water for 5 minutes, and then rinsed with ion exchange water for 20 seconds. Subsequently, the scratch of the polished substrate was measured and evaluated based on the following conditions. The results are shown in Table 1 below. The data shown in the following Table 1 is obtained by polishing four polished substrates for each example , each reference example, and each comparative example, and then measuring both surfaces of each polished substrate. ) Data average.

[Polished substrate]
As the substrate to be polished, a substrate obtained by rough polishing an aluminum alloy substrate plated with Ni-P in advance with a polishing composition containing an alumina abrasive was used. The substrate to be polished has a thickness of 1.27 mm, an outer diameter of 95 mm, an inner diameter of 25 mm, a center line average roughness Ra measured by AFM (Digital Instrument Nanoscope IIIa Multi Mode AFM), 1 nm, and a long wavelength. The amplitude of the undulation (wavelength 0.4 to 2 mm) was 2 nm, and the amplitude of the short wavelength undulation (wavelength 50 to 400 μm) was 2 nm.

[Polishing conditions]
Polishing tester: "Fast double-sided 9B polishing machine" manufactured by Speedfam
Polishing pad: Fujibo's suede type (thickness 0.9mm, average hole diameter 30μm)
Polishing liquid composition supply amount: 100 mL / min (supply rate per 1 cm ^{2 of} polishing substrate: 0.072 mL / min)
Lower platen rotation speed: 32.5 rpm
Polishing load: 6.6 kPa
Polishing time: 6 minutes

[Measurement method of polishing rate]
The weight of each substrate before and after polishing was measured using a mass meter (“BP-210S” manufactured by Sartorius) to determine the mass change of each substrate, and the average value of 10 substrates was used as the mass reduction amount, which was used as the polishing time. The value divided by was taken as the mass reduction rate. This mass reduction rate was introduced into the following equation and converted into a polishing rate (μm / min). The results are shown in Table 1 below as relative values with Comparative Example 1 taken as 100.
Polishing rate (μm / min) = mass reduction rate (g / min) / substrate single-sided area (mm ² ) / Ni-P plating density (g / cm ³ ) × 10 ⁶ (substrate single-sided area: 6597 mm ² , Ni-P Plating density: calculated as 7.9 g / cm ³ )

[Scratch evaluation method]
Measuring instrument: OSA7100, manufactured by KLA Tencor
Evaluation: Four substrates were randomly selected from the substrates put into the polishing tester, and each substrate was irradiated with a laser at 10,000 rpm to measure scratches. The total number of scratches (lines) on each of the four substrates was divided by 8 to calculate the number of scratches per substrate surface. The results are shown in Table 1 below as relative values with Comparative Example 1 taken as 100.

As shown in Table 1, when Comparative Examples 1 to 6 and Comparative Examples 3 to 8 are correspondingly compared, the combination of the component (d) and the component (e) makes it possible to add scratch without impairing the polishing rate. Or synergistically reduced. On the other hand, in the PAM (Comparative Example 9), which is a water-soluble polymer not containing carboxylic acid and sulfonic acid, the polishing rate was greatly impaired. In PVA (Comparative Example 10), aggregation occurred and polishing could not be performed.

[ Reference Example 7 and Comparative Examples 11 to 13]
In addition to using those described in the following Table 2 instead of the components of Example 1 (d) was prepared polishing composition of Example 1 in the same manner as in Reference Example 7 and Comparative Examples 11 to 13, as described above Next, the substrate to be polished was polished, and the scratch and polishing rate were calculated. The results are shown in the following Table 2 together with the results of Reference Example 1 as relative values with Comparative Example 1 taken as 100.
<Used component (d)>
Reference Example 7: The number of carbon atoms in the alkyl group was 12, the number of ethylene oxide groups was 2, and the sodium salt C ₁₂ —O (EO) ₂ SO ₃ Na (Emar E-27C, manufactured by Kao Corporation) was used.
Comparative Example 11: The number of carbon atoms in the alkyl group was 12, the number of ethylene oxide groups was 0, and the sodium salt C ₁₂ -OSO ₃ Na (Emar 2F-30, manufactured by Kao Corporation) was used.
Comparative example 12: 12 carbon atoms of alkyl group, 1 ethylene oxide group, sodium salt C ₁₂ -O (EO) ₁ SO ₃ Na (Emar 125HP, manufactured by Kao Corporation) was used.
Comparative Example 13: The number of carbon atoms in the alkyl group was 13, the number of ethylene oxide groups was 5, and the sodium salt C ₁₃ —O (EO) ₅ SO ₃ Na (Newcol 1305SF, manufactured by Nippon Emulsifier Co., Ltd.) was used.

As shown in Table 2, in Reference Examples 1 and 7 having 3 and 2 ethylene oxide groups, the polishing rate was maintained as compared with Comparative Examples 11 to 13 having 0, 1, and 5 ethylene oxide groups, and scratches were maintained. The number was decreasing. In Comparative Example 13, aggregation occurred.

[ Reference Example 8 , Examples 9 to 10 and Comparative Examples 14 to 17]
Reference Example 1 component instead in (d) of addition was used in the following Table 3 the same manner as in Reference Example 1 Reference Example 8, the polishing compositions of Examples 9-10 and Comparative Examples 14 to 17 The prepared substrate was polished in the same manner as described above, and the scratch and polishing rate were calculated. The results are shown in the following Table 3 together with the results of Reference Example 1 as relative values with Comparative Example 1 taken as 100.
<Used component (d)>
Reference Example 8: The number of carbon atoms in the alkyl group was 10, the number of ethylene oxide groups was 3, and the sodium salt C ₁₀ —O (EO) ₃ SO ₃ Na was used. (Synthetic product: Synthesis was performed according to the method disclosed in International Publication No. 2009/069826.)
Example 9: The number of carbon atoms in the alkyl group was 14, the number of ethylene oxide groups was 3, and the sodium salt C ₁₄ —O (EO) ₃ SO ₃ Na was used. ((Synthetic product: Synthesis was performed according to the method disclosed in International Publication No. 2009/069826).
Example 10: The number of carbon atoms in the alkyl group was 16, the number of ethylene oxide groups was 3, and the ammonium salt C ₁₆ —O (EO) ₃ SO ₃ NH ₄ was used. (Synthetic product: Synthesis was performed according to the method disclosed in International Publication No. 2009/069826.)
Comparative Example 14: An alkyl group having 8 carbon atoms, 3 ethylene oxide groups, and an ammonium salt C ₈ —O (EO) ₃ SO ₃ NH ₄ (Witcolate 1247H, manufactured by Akzo Nobel) was used.
Comparative Example 15: The number of carbon atoms in the alkyl group was 18, the number of ethylene oxide groups was 3, and the ammonium salt C ₁₈ —O (EO) ₃ SO ₃ NH ₄ was used. (Synthetic product: Synthesis was performed according to the method disclosed in International Publication No. 2009/069826.)
Comparative Example 16: —SO ₃ Na group, ethylene oxide group number 3, sodium salt NaSO ₃ —O (EO) ₅ SO ₃ Na was used instead of the alkyl group. (Synthetic product: Synthesis was performed according to the method disclosed in International Publication No. 2009/069826.)
Comparative Example 17: Bz—O (EO) ₂ H (Bz-20, manufactured by Nippon Emulsifier Co., Ltd.), which is a hydrogen atom, was used in place of the alkyl group instead of the benzyl group, ethylene oxide group number 3, and sulfonic acid group sodium salt.

As shown in Table 3, in Reference Examples 1 and 8 where the carbon number of the alkyl group is 10 to 16, and Examples 9 to 10, there are no Comparative Examples 14 and 15 of the alkyl group having 8 and 18 carbon atoms, and no alkyl group. As compared with Comparative Examples 16 and 17, the number of scratches was reduced while maintaining the polishing rate.

[ Reference Example 11 and Comparative Examples 18 and 19]
In addition to using those described in the following Table 4 in place of the components of Example 1 (d) was prepared polishing composition in the same manner as in Reference Example 1 Reference Example 11 and Comparative Examples 18 and 19, as described above Next, the substrate to be polished was polished, and the scratch and polishing rate were calculated. The results are shown in the following Table 4 together with the results of Reference Example 1 as relative values with Comparative Example 1 taken as 100.
<Used component (d)>
Reference Example 11 12 carbon atoms in the alkyl group, ethylene oxide groups 3, of the sulfonic acid groups ammonium salt instead of the sulfonic acid sodium salt _{C 12 -O (EO) 3 SO} 3 NH 4 ( Tainorin AESA-25, New Japan Rika Co., Ltd.) was used.
Comparative Example 18: 13 carbon atoms of alkyl group, 3 ethylene oxide groups, C ₁₃ -O (EO) ₃ PO ₃ H of phosphoric acid group instead of sodium salt of sulfonic acid group (phosphanol RS-410, Toho Chemical Industry) Used).
Comparative Example 19 12 carbon atoms in the alkyl group, ethylene oxide groups 3, C ₁₂ -O hydrogen atom in place of the sulfonic acid group, sodium salt (EO) ₃ H (Newcol 2303, manufactured by Nippon Emulsifier Co., Ltd.) was used.

As shown in Table 4, even when the sodium salt of component (d) in Reference Example 1 became an ammonium salt ( Reference Example 11), the effects of maintaining the polishing rate and reducing scratches were similarly shown. On the other hand, in Comparative Examples 18 and 19 in which the sulfonic acid group of the component (d) of Reference Example 1 was a phosphoric acid group or a hydrogen atom, the polishing rate decreased and the scratch reduction effect was also low.

[ Reference Example 12-16]
0.005 wt% and the content of the components of Example 1 (d), 0.010 wt%, 0.100 wt%, and the reference example 12 to 16 0.300 wt%, and 0.500 wt% A polishing composition was prepared, the substrate to be polished was polished in the same manner as described above, and the scratch and polishing rate were calculated. The results are shown in Table 5 below together with the results of Comparative Examples 1 and 3 as relative values with Comparative Example 1 taken as 100.

As shown in Table 5, in Reference Examples 12 to 16 to which the component (d) was added, the polishing rate was maintained and the number of scratches was reduced as compared with Comparative Examples 1 and 3. In Reference Example 16, bubbles were generated during polishing.

[ Reference Example 17-20]
The content of component (d) in Reference Example 1 is 0.005% by mass, 0.010% by mass, 0.050% by mass, and 0.059% by mass, and the content of component (e) is 0.059%, respectively. The polishing liquid compositions of Reference Examples 17 to 20 having a mass%, 0.054 mass%, 0.014 mass%, and 0.005 mass% were prepared, and the substrate to be polished was polished in the same manner as described above, and scratched. And the polishing rate was calculated. The results are shown in the following Table 6 together with the results of Reference Example 1 as relative values with Comparative Example 1 taken as 100. Further, the content ratio (% by mass /% by mass) of the component (d) and the component (e) is calculated and shown in Table 6 below.

  As shown in Table 6, the number of scratches can be reduced while maintaining the polishing rate when the content ratio (mass% / mass%) of the ingredient (d) and the ingredient (e) is in the range of 0.08 to 11.80. It has been shown.

[ Reference Examples 21-24]
The polishing liquid composition of Reference Examples 21-24 was prepared by adding the component (g) aliphatic amine compound or alicyclic amine compound and the component (h) heterocyclic aromatic compound to the polishing liquid composition of Reference Example 19. (Table 7 below). Using these polishing liquid compositions, the substrate to be polished was polished in the same manner as described above, and scratches and polishing rates were calculated. The results are shown in Table 7 below together with the results of Reference Example 1 and Comparative Examples 1 and 3 as relative values with Comparative Example 1 taken as 100. Further, A-EA (N-aminoethylethanolamine) and HEP (hydroxyethylpiperazine) were used as the component (g), and BTA (1H-benzotriazole) was used as the component (h).

As shown in Table 7, Reference Example 21-24 containing (g) an aliphatic amine compound and an alicyclic amine compound and further a component (h) a heterocyclic aromatic compound was polished even when compared with Reference Example 1. It was shown that the reduction in the number of scratches was further promoted while maintaining the speed.

[ Reference Examples 25-29]
Components of the polishing composition of Example 21 oxyalkylene alkyl ether sulfate and component (g) of Reference Example 25 to 29 which changes were added as shown in Table 8 aliphatic amine compound content of the complex of (d) A polishing composition was prepared (Table 8 below). Using these polishing liquid compositions, the substrate to be polished was polished in the same manner as described above, and scratches and polishing rates were calculated. The results are shown in Table 8 below as relative values with Comparative Example 1 taken as 100. Further, the content ratio (% by mass /% by mass) of the component (d) and the component (g) is calculated and shown in Table 8 below. In addition, A-EA (N-aminoethylethanolamine) was used as a component (g).

  As shown in Table 8 above, the number of scratches can be reduced while maintaining the polishing rate when the content ratio (% by mass /%) of the component (d) and the component (g) is in the range of 0.05 to 19.0. It has been shown.

[Examples 30 and 31]
The polishing liquid compositions of Examples 30 and 31 were prepared in the same manner as in Reference Example 1 except that the components listed in Table 9 below were used instead of the component (d) in Reference Example 22, and the substrate to be polished was the same as described above. The scratches and the polishing rate were calculated. The results are shown in Table 9 below together with the results of Reference Example 22 as relative values with Comparative Example 1 taken as 100.
<Used component (d)>
Example 30: The alkyl group used in Example 9 had 14 carbon atoms, 3 ethylene oxide groups, and the sodium salt C ₁₄ —O (EO) ₃ SO ₃ Na.
Example 31: The alkyl group used in Example 10 had 16 carbon atoms, 3 ethylene oxide groups, and the sodium salt C ₁₆ -O (EO) ₃ SO ₃ NH ₄ was used.

As shown in Table 9, in Reference Example 22, Examples 30 and 31, where the alkyl group had 12 to 16 carbon atoms, the number of scratches was reduced while maintaining the polishing rate.

[Comparative Examples 20-22]
The polishing liquid compositions of Comparative Examples 20 to 22 using alumina particles (secondary particle size: 340 nm) in place of the silica particles of component (a) were prepared (Table 10 below). Polishing was performed, and scratches and polishing rates were calculated. The results are shown in the following Table 10 together with the results of Reference Example 1 as relative values with Comparative Example 1 taken as 100.

  As shown in Table 10, in the polishing liquid compositions of Comparative Examples 20 to 22 containing alumina particles, no improvement in scratch was confirmed against a decrease in polishing rate.

[ Reference Example 32, Comparative Examples 23 to 25]
The pH (1.3) of the polishing composition of Example 1, except that was pH2.0 or 3.0 to prepare a polishing composition in the same manner as in Reference Example 1 Reference Example 32 and Comparative Example 23, The substrate to be polished was polished in the same manner as described above, and the scratch and polishing rate were calculated. Further, the polishing composition of Comparative Examples 24 and 25 was prepared in the same manner as Comparative Example 3 except that the pH (1.3) of the polishing composition of Comparative Example 3 was set to pH 2.0 or 3.0. The substrate to be polished was polished in the same manner as described above, and the scratch and polishing rate were calculated. These results are shown in Table 11 below together with the results of Reference Example 1 as relative values with Comparative Example 1 taken as 100.

As shown in Table 11, in Reference Example 1 and Reference Example 32 having a pH of less than 3.0, the number of scratches was reduced while maintaining the polishing rate.

Claims (9)

(A) silica particles, (b) acid, (c) oxidizing agent, (d) oxyalkylene alkyl ether sulfate compound represented by the following general formula (I), (e) sulfonic acid group and carboxylic acid group Magnetic disk substrate polishing liquid for polishing an Ni-P plated aluminum alloy substrate, containing an anionic polymer having at least one and (f) water and having a pH of less than 3.0 at 25 ° C. Composition.
R-O- (EO) n- SO 3 M (I)
[In the formula (I), R represents a linear or branched hydrocarbon group having 14 to 16 carbon atoms, and M represents hydrogen, an alkali metal, an ammonium ion, or an alkylammonium ion. EO represents an ethylene oxide group, and n represents a natural number of 2 or more and 4 or less. ]   2. The polishing composition for a magnetic disk substrate according to claim 1, wherein the content of the component (d) oxyalkylene alkyl ether sulfate-based compound is 0.005% by mass or more and 0.5% by mass or less when used.   Content ratio [(d) (mass%) / (e) of said component (d) oxyalkylene alkyl ether sulfate type compound and said component (e) at least one of a sulfonic acid group and a carboxylic acid group ) (Mass%)] is a polishing composition for a magnetic disk substrate according to claim 1, wherein the polishing composition is 0.05 to 12.00. The polishing composition for a magnetic disk substrate according to any one of claims 1 to 3 , further comprising a component (g) an aliphatic amine compound or an alicyclic amine compound. Content ratio [(d) (mass%) / (g) (mass%)] of component (d) oxyalkylene alkyl ether sulfate compound and component (g) aliphatic amine compound and alicyclic amine compound The polishing composition for a magnetic disk substrate according to claim 4 , wherein is from 0.04 to 20.00. The polishing composition for a magnetic disk substrate according to any one of claims 1 to 5 , further comprising a component (h) a heteroaromatic compound. The anionic polymer having at least one of the component (e) sulfonic acid group and carboxylic acid group is an acrylic acid / 2-acrylamido-2-methylpropanesulfonic acid copolymer and / or a salt thereof. 7. A polishing composition for a magnetic disk substrate according to any one of items 1 to 6 . Using magnetic disk substrate polishing composition according to any one of claims 1 to 7 comprising the step of polishing the substrate, a manufacturing method of a magnetic disk substrate. Using magnetic disk substrate polishing composition according to any one of claims 1 to 7 comprising the step of polishing the substrate, a polishing method of a magnetic disk substrate.