JP4336550B2 - Polishing liquid kit for magnetic disk - Google Patents

Description

The present invention relates to a magnetic disk polishing liquid kit, a magnetic disk substrate polishing method, and a magnetic disk substrate manufacturing method.

  Hard disks are required to reduce the flying height of the magnetic head and prevent surface defects (surface contamination) in order to reduce the minimum recording area and increase the capacity. In order to reduce the flying height of the head, polishing liquid compositions containing alumina, an oxidizing agent, and an acid have been studied (Patent Documents 1 and 2).

However, these polishing liquid compositions have a problem in reproducibility because the polishing rate may not be sufficiently exhibited depending on the storage period after preparation. Therefore, for example, when the polishing rate decreases, in order to ensure the necessary amount of polishing, the polishing time is lengthened or the polishing liquid composition is used at a lower dilution rate to increase the polishing liquid concentration during use. It is necessary to perform work such as maintaining speed, resulting in problems such as higher costs and lower productivity.
JP 2003-147337 A Japanese Patent Laid-Open No. 11-246849

  SUMMARY OF THE INVENTION An object of the present invention is to provide a magnetic disk polishing liquid kit and a magnetic disk substrate that can exhibit a high polishing rate with good reproducibility without depending on the storage period in a magnetic disk polishing liquid containing alumina, an oxidizing agent, and an acid. It is another object of the present invention to provide a polishing method and a method for manufacturing a high-quality magnetic disk substrate.

That is, the gist of the present invention is as follows.
[1] A slurry (A) composed of alumina , sulfuric acid and / or a salt thereof, water , an additive liquid (D) containing an inorganic acid selected from sulfuric acid, sulfurous acid and amidosulfuric acid and hydrogen peroxide, and organic A polishing liquid kit for a magnetic disk comprising at least an acid solution (c) containing an organic acid selected from sulfonic acids, organic phosphonic acids, and polyvalent carboxylic acids, each contained in a separate container, In the slurry (A), when the sulfuric acid is contained, the content is 0.01 to 3% by weight, and when the sulfuric acid salt is contained, the content is 0.05 to 15% by weight . Polishing fluid kit,
[2] At least an inorganic acid and hydrogen peroxide selected from a slurry (A) made of alumina, sulfuric acid and / or a salt thereof, water, sulfuric acid, sulfurous acid and amidosulfuric acid, each contained in a separate container. And a liquid mixture obtained by mixing an additive liquid (D) containing a liquid and an acid liquid (c) containing an organic acid selected from organic sulfonic acids, organic phosphonic acids and polyvalent carboxylic acids. And polishing cloth to polish the magnetic disk substrate, wherein the slurry (A) has a content of 0.01 to 3% by weight when sulfuric acid is contained. A polishing method in which the content in the case of containing a salt is 0.05 to 15% by weight , and [3] a method of manufacturing a polished magnetic disk substrate having the following steps:
(1) At least an inorganic acid and hydrogen peroxide selected from a slurry (A) made of alumina, sulfuric acid and / or a salt thereof, water, sulfuric acid, sulfurous acid and amidosulfuric acid, each contained in a separate container. A step of preparing a polishing liquid by mixing an additive liquid (D) containing an acid solution (c) containing an organic acid selected from organic sulfonic acids, organic phosphonic acids and polyvalent carboxylic acids, wherein In the slurry (A), the content when containing sulfuric acid is 0.01 to 3% by weight, and the content when containing a salt of sulfuric acid is 0.05 to 15% by weight.
(2) a step of pressing the magnetic disk substrate against the polishing cloth of the polishing platen and applying pressure;
(3) The present invention relates to a step of polishing the magnetic disk substrate by moving the substrate and the polishing platen while supplying the polishing liquid prepared in step (1) between the magnetic disk substrate and the polishing pad .

  By using the magnetic disk polishing liquid kit of the present invention, a high polishing rate is expressed with good reproducibility without depending on the storage period, and therefore, an effect that a high-quality magnetic disk can be manufactured at low cost. Played.

a) Magnetic Disk Polishing Liquid Kit The magnetic disk polishing liquid kit of the present invention is roughly classified into the following three types.
(Aspect a-1) Magnetic disk polishing liquid kit comprising at least a slurry (A) containing alumina, an oxidant solution (B) containing an oxidant, and an acid solution (C) containing an acid,
(Aspect a-2) A magnetic disk comprising at least an acid solution (c) containing an organic acid, and at least a slurry (A) containing alumina and an additive solution (D) containing an oxidant and an inorganic acid. Polishing liquid kit,
(Aspect a-3) A polishing disk kit for a magnetic disk, which is composed of at least a slurry (A) containing alumina and an acid solution (C) containing an acid and used together with an oxidant solution (B) containing an oxidant.

  The magnetic disk polishing liquid kit of the present invention (hereinafter simply referred to as a kit) has one major characteristic in having the above-described configuration. By having such characteristics, it is possible to prevent the decrease in polishing rate by suppressing the generation of salt and decomposition of each component caused by the reaction of each component, so reproducibility without depending on the shelf life of the kit. There is an effect that a high polishing rate can be expressed well.

  Each component used in the embodiments a-1 to a-3 will be described below.

(A) Component: Slurry Containing Alumina The slurry of component (A) contains at least alumina and does not substantially contain an organic acid or an oxidizing agent described below from the viewpoint of storage stability.

  The alumina used in the present invention is preferably alumina having a purity of 95% or more, more preferably 97% or more, and still more preferably from the viewpoints of waviness reduction, surface roughness reduction, polishing rate improvement and surface defect prevention. Is 99% or more of alumina. Further, α-alumina is preferable from the viewpoint of improving the polishing rate, and intermediate alumina such as γ-alumina, δ-alumina, θ-alumina, η-alumina, and κ-alumina is preferable from the viewpoint of reducing the surface properties and waviness. preferable. The intermediate alumina of the present invention is a general term for alumina particles other than α-alumina particles, and specifically includes γ-alumina, δ-alumina, θ-alumina, η-alumina, κ-alumina, and mixtures thereof. Can be mentioned. Among the intermediate aluminas, γ-alumina, δ-alumina, θ-alumina and a mixture thereof are preferable from the viewpoint of improving the polishing rate and reducing waviness, and γ-alumina and θ-alumina are particularly preferable.

  From the viewpoint of reducing waviness, the average particle size of primary particles of alumina is more preferably 0.005 to 0.8 μm, particularly preferably 0.01 to 0.4 μm, and the average particle size of secondary particles is 0.01 to 2 μm is more preferable, 0.05 to 1.0 μm is more preferable, and 0.1 to 0.5 μm is particularly preferable. The average particle size of the primary particles of the abrasive is observed with a scanning electron microscope (preferably 3000 to 30000 times) or observed with a transmission electron microscope (preferably 10000 to 300000 times), and image analysis is performed. It can be determined by measuring the diameter. The average particle size of the secondary particles can be measured as a volume average particle size using a laser beam diffraction method.

In particular, when the alumina is intermediate alumina, the specific surface area measured by the BET method is preferably 30 to 300 m ² / g, more preferably 50 to 200 m ² / g.

  From the viewpoint of improving the polishing rate and reducing waviness, a mixed system of α-alumina and intermediate alumina is effective as the alumina abrasive grains. In this case, the weight ratio of α-alumina to intermediate alumina (α-alumina / intermediate alumina) is preferably 99/1 to 30/70, more preferably 97/3 to 40/60, and still more preferably 95/5. 50/50, most preferably 93/7 to 55/45.

  The content of alumina is preferably 0.1% by weight or more, more preferably 0.5% by weight or more, and still more preferably 1% by weight or more in the slurry from the viewpoint of improving the polishing rate and economy. From the viewpoint of dispersion stability of the slurry, it is preferably 60% by weight or less, more preferably 50% by weight or less, and still more preferably 40% by weight or less. That is, the content of alumina in the slurry is preferably 0.1 to 60% by weight, more preferably 0.5 to 50% by weight, and still more preferably 1 to 40% by weight.

  The slurry of component (A) may contain a necessary amount of an inorganic acid such as sulfuric acid or nitric acid or a salt thereof in order to enhance dispersion stability and anti-caking property. As content of an inorganic acid, Preferably it is 0.01 to 5 weight%, More preferably, it is 0.02 to 3 weight%, More preferably, it is 0.03 to 1 weight%. The content of the inorganic acid salt is preferably 0.01 to 30% by weight, more preferably 0.05 to 20% by weight, and still more preferably 0.1 to 15% by weight.

  Examples of the slurry medium include water such as ion-exchanged water, pure water, and ultrapure water, but may contain a bactericide, an antibacterial agent, a pH adjuster, and the like. Moreover, you may contain abrasives, such as a silica. The water content is more preferably 40% by weight or more, and further preferably 40 to 99.9% by weight in the slurry from the viewpoint of dispersion stability.

(B) Component: Oxidizing agent solution containing an oxidizing agent The (B) component oxidizing agent solution is a solution containing at least an oxidizing agent, and from the viewpoint of storage stability, a metal ion that causes decomposition of the oxidizing agent, A metal oxide and an organic compound are not substantially contained. Therefore, an organic phosphonic acid such as hydroxyethylidene-1,1-diphosphonic acid that does not decompose the oxidizing agent may be contained.

  Examples of the oxidizing agent used in the present invention include peroxides, metal peroxo acids or salts thereof, oxygen acids or salts thereof, nitrates, sulfates, and metal salts of acids. Oxidizing agents are roughly classified into inorganic oxidizing agents and organic oxidizing agents based on their structures. Specific examples of these oxidizing agents are shown below. Examples of inorganic oxidizing agents include hydrogen peroxide, and also alkali metals such as sodium peroxide, potassium peroxide, calcium peroxide, barium peroxide, magnesium peroxide, or alkaline earth metal peroxides, peroxo Peroxocarbonates such as sodium carbonate, potassium peroxocarbonate, peroxosulfuric acid such as ammonium peroxodisulfate, sodium peroxodisulfate, potassium peroxodisulfate, peroxomonosulfuric acid or the like, peroxonitric acid such as peroxonitric acid, sodium peroxonitrate, potassium peroxonitrate Or peroxophosphoric acid such as sodium peroxophosphate, potassium peroxophosphate, ammonium peroxophosphate or salts thereof, peroxophosphoric acid such as sodium peroxoborate, potassium peroxoborate, etc. Acid salts, peroxochromates such as potassium peroxochromate and sodium peroxochromate, permanganates such as potassium permanganate and sodium permanganate, sodium perchlorate, potassium perchlorate, chloric acid, hypochlorous acid Halogen acids such as sodium chlorate, sodium periodate, potassium periodate, iodic acid, sodium iodate, or derivatives thereof, and inorganic acid metal salts such as iron (III) chloride and iron (III) sulfate may be used. it can. Examples of organic oxidants include percarboxylic acids such as peracetic acid, performic acid and perbenzoic acid, peroxides such as t-butyl peroxide and cumene peroxide, and organic acid iron salts such as iron (III) citrate. Can be used. Of these, inorganic oxidizers are preferred when the polishing rate improvement property, availability, and handleability such as water solubility are compared. Furthermore, in view of environmental problems, an inorganic peroxide containing no heavy metal is preferable. Further, from the viewpoint of preventing surface contamination of the substrate to be polished, hydrogen peroxide, peroxosulfates, halogen acids or derivatives thereof are more preferable, and hydrogen peroxide is particularly preferable. These peroxides may be used alone or in combination of two or more.

  Further, the oxidizing agent solution of the component (B) may contain an inorganic acid such as sulfuric acid, nitric acid, hydrochloric acid, phosphoric acid, etc. described later.

  The content of the oxidizing agent is preferably 0.005% by weight or more, more preferably 0.007% by weight or more in the oxidizing agent solution from the viewpoint of improving the polishing rate and reducing waviness. Moreover, from a viewpoint of surface quality, Preferably it is 60 weight% or less, More preferably, it is 50 weight% or less. That is, the content of the oxidizing agent in the oxidizing agent solution is preferably 0.005 to 60% by weight, more preferably 0.007 to 50% by weight.

  The medium for the oxidant liquid is preferably water such as ion exchange water, pure water, or ultrapure water. The water content is preferably 40% by weight or more, and more preferably 40 to 99.995% by weight.

(C) Component: Acid solution containing acid (C) The acid solution of component (C) is a solution containing at least an acid, and from the viewpoint of storage stability, a metal oxide such as alumina that reacts with the acid. Is not substantially contained. Moreover, when an acid agent liquid contains an organic acid, it does not contain an oxidizing agent further.

Examples of the acid include inorganic acids and organic acids.
Inorganic acids include nitrogen-containing inorganic acids such as nitric acid and nitrous acid, sulfur-containing inorganic acids such as sulfuric acid, sulfurous acid and amidosulfuric acid, phosphorus-containing inorganic acids such as phosphoric acid, pyrophosphoric acid, polyphosphoric acid and phosphonic acid, hydrochloric acid and odorous acid And halogen-containing inorganic acids such as Among these, from the viewpoint of improving the polishing rate, nitric acid, nitrous acid, sulfuric acid, sulfurous acid, and amidosulfuric acid are preferable, sulfuric acid, sulfurous acid, and amidosulfuric acid are more preferable, and sulfuric acid is particularly preferable. The content of the inorganic acid is preferably 0.005% by weight or more, more preferably 0.007% by weight or more in the acid solution, and preferably 60% by weight or less, more preferably 50% from the viewpoint of surface quality. % By weight or less. That is, the content of the inorganic acid in the acid agent solution is preferably 0.005 to 60% by weight, more preferably 0.007 to 50% by weight.

  The organic acid preferably has a pK1 of 7 or less, more preferably 5 or less, still more preferably 4 or less, and particularly preferably 2 or less from the viewpoint of improving the polishing rate and reducing waviness. Here, pK1 represents the logarithmic value of the reciprocal of the first acid dissociation constant at 25 ° C. PK1 of each compound is described in Chemical Handbook 4th edition (basic edition) II, pp316-325 (edited by Chemical Society of Japan).

  The organic acid is preferably a sulfur-containing organic acid, a carboxylic acid, or a phosphorus-containing organic acid from the viewpoints of improving the polishing rate, reducing waviness, and preventing surface contamination. Specific examples are shown below. Monocarboxylic acid such as formic acid, acetic acid, glycolic acid, lactic acid, propanoic acid, hydroxypropanoic acid, butyric acid, benzoic acid, glycine, oxalic acid, succinic acid, glutaric acid, adipic acid, maleic acid, fumaric acid, itaconic acid, apple Acid, tartaric acid, citric acid, isocitric acid, phthalic acid, nitrotriacetic acid, ethylenediaminetetraacetic acid and other polyvalent carboxylic acids, methanesulfonic acid, paratoluenesulfonic acid, sulfur-containing organic acids such as alkyl sulfuric acid, ethyl phosphoric acid, butyl phosphoric acid, Examples thereof include phosphorus-containing organic acids such as lauryl phosphoric acid, phosphonohydroxyacetic acid, hydroxyethylidene-1,1-diphosphonic acid, phosphonobutanetricarboxylic acid, and ethylenediaminetetramethylenephosphonic acid. Of these, sulfur-containing organic acids and phosphorus-containing organic acids are preferable from the viewpoint of improving the polishing rate and reducing waviness, more preferably organic sulfonic acids and organic phosphonic acids, and still more preferably organic sulfonic acids. From the viewpoint of contamination of the object to be polished, sulfur-containing organic acids and carboxylic acids are preferable, and organic sulfonic acids and polyvalent carboxylic acids are more preferable. These compounds may be used alone or in combination.

  The content of the organic acid is preferably 0.005% by weight or more, more preferably 0.007% by weight or more in the acid solution, from the viewpoint of improving the polishing rate and reducing waviness. Moreover, from a viewpoint of surface quality and economical efficiency, Preferably it is 60 weight% or less, More preferably, it is 50 weight% or less. That is, the content of the organic acid in the acid agent solution is preferably 0.005 to 60% by weight, more preferably 0.007 to 50% by weight.

  As the medium for the acid solution, water such as ion exchange water, pure water, or ultrapure water is preferable. The water content is preferably 40% by weight or more, and more preferably 40 to 99.95% by weight.

  Further, the pH of the acid agent solution is preferably 6 or less, more preferably 0.1 to 5, and further preferably 0.2 to 4. These pHs can be adjusted by adding a basic substance such as ammonia, sodium hydroxide, or potassium hydroxide, or adding a salt such as an ammonium salt, sodium salt, or potassium salt of the contained acid.

Component (D): Additive liquid containing oxidizing agent and inorganic acid (D) The additive liquid of component includes at least the above oxidizing agent and inorganic acid, and causes metal ions and metals that cause decomposition of the oxidizing agent. It is substantially free of oxides and organic compounds. Therefore, an organic phosphonic acid such as hydroxyethylidene-1,1-diphosphonic acid that does not decompose the oxidizing agent may be contained. The content of the oxidizing agent and the content of the inorganic acid are the same as described above.
The total amount of these components is preferably 0.01% by weight or more, more preferably 0.01 to 80% by weight in the additive solution.

  Moreover, as a medium of this additive liquid, water, such as ion-exchange water, a pure water, and an ultrapure water, is preferable. The water content is preferably 20% by weight or more, and more preferably 20 to 99.99% by weight.

(C) Component: Acid solution containing an organic acid (c) Component refers to an acid solution containing at least an organic acid and used in combination with the component (D). If it is the same as that of the said (C) component as a kind of organic acid and its usage-amount, there will be no limitation in particular.

  Each kit of this aspect a-1, a-2, and a-3 has each alumina, an oxidizing agent, and an acid in the polishing liquid composition obtained by mix | blending the component of each kit in predetermined range. As shown, each component is blended and used. Moreover, you may mix and use water, such as ion-exchange water, a pure water, and an ultrapure water, as needed.

  The content of alumina in the polishing composition is preferably 0.05% by weight or more, more preferably 0.1% by weight or more, still more preferably 0.5% by weight or more, and particularly preferably 1 from the viewpoint of improving the polishing rate and reducing waviness. % By weight or more. Further, from the viewpoint of surface quality and economy, it is preferably 40% by weight or less, more preferably 30% by weight or less, still more preferably 25% by weight or less, and particularly preferably 20% by weight or less. That is, the content of alumina in the polishing composition is preferably 0.05 to 40% by weight, more preferably 0.1 to 30% by weight, still more preferably 0.5 to 25% by weight, and particularly preferably 1 to 20% by weight. .

  The content of the oxidizing agent in the polishing liquid composition is preferably 0.002% by weight or more, more preferably 0.005% by weight or more, and further preferably 0.007% by weight or more, from the viewpoints of improving the polishing rate, reducing waviness, and reducing substrate contamination. Particularly preferred is 0.01% by weight or more. From the viewpoint of surface quality and economy, it is preferably 20% by weight or less, more preferably 15% by weight or less, still more preferably 10% by weight or less, and particularly preferably 5% by weight or less. That is, the content of the oxidizing agent in the polishing composition is preferably 0.002 to 20% by weight, more preferably 0.005 to 15% by weight, still more preferably 0.007 to 10% by weight, and particularly preferably 0.01 to 5% by weight. is there.

  The acid content in the polishing composition is preferably 0.002% by weight or more, more preferably 0.005% by weight or more, and still more preferably 0.007% by weight, from the viewpoint of achieving both improvement in polishing rate, reduction in waviness, and substrate contamination. Above, particularly preferably 0.01% by weight or more. From the viewpoint of surface quality and economy, it is preferably 20% by weight or less, more preferably 15% by weight or less, still more preferably 10% by weight or less, and particularly preferably 5% by weight or less. That is, the acid content in the polishing composition is preferably 0.002 to 20% by weight, more preferably 0.005 to 15% by weight, still more preferably 0.007 to 10% by weight, and particularly preferably 0.01 to 5% by weight. .

  Moreover, in the kit of this invention, an inorganic salt, a thickener, a rust preventive agent, a basic substance, etc. can be suitably mix | blended with each component as needed. These compounds may be used alone or in combination of two or more. Moreover, the content is preferably 0.05 to 20% by weight, more preferably 0.05 to 10% by weight, and still more preferably 0.05 to 5% in the polishing composition obtained from the kit, from the viewpoint of economy. % By weight.

  Furthermore, a bactericidal agent, an antibacterial agent, etc. can be mix | blended with each component of a kit as needed. The content of these bactericides and antibacterial agents is preferably 0.0001 to 0.1% by weight, more preferably in the polishing liquid composition obtained from the kit, from the viewpoint of exerting the function, and from the viewpoints of influence on polishing performance and economy. Is 0.001 to 0.05% by weight, more preferably 0.002 to 0.02% by weight.

  The balance of the polishing composition is water. The amount of water is preferably 55 to 99% by weight, more preferably 60 to 99% by weight, and still more preferably 70 to 95% by weight in the polishing composition.

  Further, the kit of the present invention has an advantage that extremely excellent storage stability can be obtained by storing each component such as the component (A) without mixing with other components. A specific embodiment of such a kit includes a kit in which each component such as the component (A) is placed in a container such as a can, drum, or container having a material resistant to each component.

  Moreover, each component of a kit can be manufactured by adding and mixing a target component by arbitrary methods.

  It is preferable that the pH of the polishing liquid obtained by blending the components of the kit of the present invention is appropriately determined according to the type of the object to be polished and the required quality. The pH is preferably as low as possible from the viewpoint of polishing rate and reduction of waviness, but the pH is preferably closer to 7 from the viewpoint of corrosion prevention of processing machines and the safety of workers. Therefore, when both are taken into account, it is preferably 0.1 or more and less than 6, more preferably 0.5 or more and less than 5, more preferably 1 or more and less than 4, and particularly preferably 1 or more and less than 3. The pH of the kit is inorganic acid such as nitric acid and sulfuric acid, oxycarboxylic acid, polyvalent carboxylic acid, aminopolycarboxylic acid, organic acid such as amino acid, and metal salts and ammonium salts thereof, ammonia, sodium hydroxide, potassium hydroxide, It can adjust by mix | blending basic substances, such as an amine, with a desired quantity suitably.

  The magnetic disk substrate, which is the substrate to be polished, which is the subject of the present invention, is used as a substrate for a magnetic recording medium. As a specific example of the magnetic disk substrate, a substrate obtained by plating a Ni—P alloy on an aluminum alloy is typical. However, a glass or glassy carbon is used instead of the aluminum alloy, and a substrate obtained by applying Ni—P plating to the glass or glass. Alternatively, instead of Ni-P plating, a substrate in which various metal compounds are coated by plating or vapor deposition can be used.

  The kit of the present invention is particularly effective in the polishing process, but can be similarly applied to other polishing processes such as a lapping process.

b) Polishing Method of Magnetic Disk Substrate The magnetic disk substrate polishing method of the present invention is roughly divided into the following modes.
(Aspect b-1) At least a mixed liquid obtained by mixing a slurry (A) containing alumina, an oxidant liquid (B) containing an oxidant, and an acid agent liquid (C) containing an acid is magnetic. A polishing method for polishing a magnetic disk substrate by supplying between the disk substrate and a polishing cloth,
(Aspect b-2) A mixed liquid obtained by mixing at least the slurry (A) containing alumina and the additive liquid (D) containing an oxidizing agent and an inorganic acid is placed between the magnetic disk substrate and the polishing cloth. Polishing method for polishing the magnetic disk substrate by supplying to
(Aspect b-3) Obtained by mixing at least a slurry (A) containing alumina, an additive solution (D) containing an oxidizing agent and an inorganic acid, and an acid solution (c) containing an organic acid. A polishing method for polishing a magnetic disk substrate by supplying a mixed liquid between the magnetic disk substrate and a polishing cloth.

  Here, the components (A), (B), (C), (D), (c), the magnetic disk substrate, etc. used in the magnetic disk substrate polishing method of the present invention are all the same as described above. If it is. Therefore, the liquid mixture used in the aspect b-1 is a polishing liquid obtained by blending the components of the kit of the aspect a-1, and the liquid mixture used in the aspects b-2 and b-3 is that of the aspect a-2. This is the same as the polishing liquid obtained by blending the components of the kit.

  The polishing cloth is not particularly limited as long as it is used in a general magnetic disk substrate polishing process, but a porous organic polymer type is preferable.

  In the polishing method of the above aspects b-1 to b-3, as a method of supplying the mixed liquid obtained by mixing each component between the magnetic disk substrate and the polishing cloth, for example, porous organic high The magnetic disk substrate is sandwiched by a polishing surface plate with a molecular polishing cloth or the like, the mixed liquid is supplied to the polishing surface, and the polishing surface plate or the magnetic disk substrate is moved while pressure is applied. Can be polished. The polishing platen is not particularly limited as long as it is used in a general magnetic disk substrate polishing process. Further, there are no particular limitations on other conditions (type of polishing apparatus, polishing temperature, polishing rate, supply amount of polishing liquid, etc.) when polishing.

  As an example of the polishing method of Embodiments b-1 to b-3, it is preferable to supply the liquid mixture obtained by stirring the components in the container before the polishing. “Before polishing” means before polishing, and from the viewpoint of the stability of the mixed solution, it is preferable that the time from mixing to use for polishing is short. The structure, size, and material of the container are not particularly limited, and may be appropriately determined according to the supply amount of the polishing liquid.

  Further, as another example of the polishing method of the embodiments b-1 to b-3, when supplying each component, supply means for supplying each component are connected at the same or different sites, and the respective components are joined together. The method of supplying a liquid mixture using the supply means to supply is mentioned. A pipe is preferably used as the supply means.

  For example, as the polishing method of aspect b-1, the component (A), the component (B), and the component (C) are supplied to the first pipe, the second pipe, and the third pipe, respectively. , The components (A) to (C) are mixed in the fourth pipe joined with the first pipe, the second pipe, and the third pipe, and then the obtained mixed solution is mixed with the fourth pipe. The method of supplying from is mentioned. Further, the fifth pipe may be joined to one or more of the first to fourth pipes for mixing water. The joining position of the first to third pipes in the fourth pipe and the size, shape, arrangement, etc. of each pipe are contained in the number, size and each component of the magnetic disk substrate to be polished. It cannot be generally limited by the concentration of a compound such as alumina, an oxidizing agent, and an acid.

  Similarly, as the polishing method of aspect b-2, the component (A) and (D) are supplied to the first pipe and the second pipe, respectively, and the first pipe and the second pipe are joined. In addition, there is a method in which the components (A) and (D) are mixed in the third pipe, and then the obtained mixed solution is supplied from the third pipe. Further, the fourth pipe may be joined to one or more of the first to third pipes for mixing water. As the polishing method of aspect b-3, the component (A), the component (D), and the component (c) are supplied to the first pipe, the second pipe, and the third pipe, respectively. In the fourth pipe in which the first pipe, the second pipe, and the third pipe are joined, the components (A), (D), and (c) are mixed, and then the obtained mixed liquid is added to the fourth pipe. The method of supplying from the pipe of this is mentioned. Further, the fifth pipe may be joined to one or more of the first to fourth pipes for mixing water. The joining position of other pipes in the third and fourth pipes, the size, shape, arrangement, etc. of each pipe are the number, size, and alumina contained in each component of the magnetic disk substrate to be polished. However, it cannot be generally limited by the concentration of a compound such as an oxidizing agent or an acid.

  By using the magnetic disk substrate polishing method of the present invention having such a configuration, an effect that a high polishing rate can be expressed with high reproducibility without depending on the storage period is exhibited.

c) Manufacturing Method of Magnetic Disk Substrate The manufacturing method of the magnetic disk substrate of the present invention is roughly divided into the following aspects.
(Aspect c-1) Magnetic disk substrate manufacturing method having the following steps:
(1) A step of preparing a polishing liquid by mixing at least a slurry (A) containing alumina, an oxidant liquid (B) containing an oxidant, and an acid agent liquid (C) containing an acid,
(2) a step of pressing the magnetic disk substrate against the polishing cloth of the polishing platen and pressurizing; and (3) supplying the polishing liquid prepared in step (1) between the magnetic disk substrate and the polishing cloth, The process of polishing the magnetic disk substrate by moving the polishing platen.
(Aspect c-2) Magnetic disk substrate manufacturing method having the following steps:
(1) A step of preparing a polishing liquid by mixing at least a slurry (A) containing alumina and an additive liquid (D) containing an oxidizing agent and an inorganic acid,
(2) a step of pressing the magnetic disk substrate against the polishing cloth of the polishing platen and pressurizing; and (3) supplying the polishing liquid prepared in step (1) between the magnetic disk substrate and the polishing cloth, The process of polishing the magnetic disk substrate by moving the polishing platen.
(Aspect c-3) Magnetic disk substrate manufacturing method having the following steps:
(1) A step of preparing a polishing liquid by mixing at least a slurry (A) containing alumina, an additive liquid (D) containing an oxidizing agent and an inorganic acid, and an acid liquid (c) containing an organic acid. ,
(2) a step of pressing the magnetic disk substrate against the polishing cloth of the polishing platen and pressurizing; and (3) supplying the polishing liquid prepared in step (1) between the magnetic disk substrate and the polishing cloth, The process of polishing the magnetic disk substrate by moving the polishing platen.

  The components (A), (B), (C), (D), (c), the magnetic disk substrate, the polishing cloth, the polishing surface plate, etc. may all be the same as described above. Therefore, the polishing liquid used in the aspect c-1 is a polishing liquid obtained by blending the components of the kit of the aspect a-1, and the mixed liquid used in the aspects c-2 and c-3 is that of the aspect a-2. This is the same as the polishing liquid obtained by blending the components of the kit.

  In the polishing step, the pressure for pressing and pressing is preferably 1 to 20 kPa, more preferably 3 to 15 kPa, from the viewpoints of improving surface smoothness, reducing surface defects, and improving the polishing rate.

Further, the method for moving the substrate and the polishing platen is not particularly limited as long as it is a known method.
By using the method for manufacturing a magnetic disk substrate of the present invention having such a configuration, the surface smoothness is improved and a high-quality magnetic disk substrate having few surface defects can be manufactured economically with good reproducibility. There is.

Examples 1 to 3 (Reference Example) , Comparative Examples 1 to 4
[Preparation of polishing liquid]
α-alumina (average primary particle size 0.07 μm, secondary particle average particle size 0.3 μm, specific surface area 15 m ² / g, purity 99.9%) 12.75% by weight, sulfuric acid 0.8% by weight, citric acid 4.28% by weight, 35 % Hydrogen peroxide solution (7.31% by weight (2.56% by weight as hydrogen peroxide)) and the remaining ion-exchanged water in a 2L polyethylene resin container so that the total weight is 1.5kg. A liquid was obtained. Furthermore, this polishing liquid and ion-exchanged water were put in a 4 L polyethylene resin container at a mixing ratio (weight ratio) of 1: 4 so that the total weight would be 4 kg, mixed by stirring, and the polishing liquid composition of Reference Example 1 was obtained. Got.

  The components (A), (B) or (D) and (C) or (c) of the polishing liquid kits of Examples 1 to 3 and Comparative Examples 1 to 4 having the configurations shown in Table 1 are each 2 L. It put into the container made from a polyethylene resin, airtight, and left still at 60 degreeC for 28 days. After allowing to stand, the components of each polishing liquid kit and ion-exchanged water were placed in a 4 L polyethylene resin container at a blending ratio (weight ratio) shown in the table so that the total weight was 4 kg, and stirred and mixed. 3 and Comparative Examples 1-4 were obtained.

As the component (A), a slurry containing 12.75% by weight of α-alumina using water as a medium was used. In the table, those having other components described were those containing a predetermined amount of these components in the slurry.
As component (B), 7.31% by weight of 35% hydrogen peroxide water (2.56% by weight as hydrogen peroxide) was used. In the table, those having other components described were used in which these components were contained in a predetermined amount in this hydrogen peroxide solution.
As the component (C), sulfuric acid and citric acid were used. The content is the amount described in the table. As the component (c), citric acid was used. The content is the amount described in the table. As component (D), sulfuric acid and hydrogen peroxide were used. The content is the amount described in the table.

  Polishing evaluation of the obtained polishing liquid composition was performed and the polishing rate was measured. Using the polishing rate of the polishing composition of Reference Example 1 as the reference value 1, the relative value (relative polishing rate) of the polishing rates of the polishing solution compositions of Examples and Comparative Examples was determined. The results are shown in Table 1. The measurement of the polishing method and the polishing rate is shown below.

[Polishing method]
Centerline average roughness Ra measured by rank tailor Hobson's tally step (stylus tip size: 25 μm x 25 μm, high-pass filter: 80 μm, measurement length: 0.64 mm), thickness 1.27 mm, diameter Polishing the surface of a 3.5-inch Ni-P plated aluminum alloy with a double-sided machine with the following double-sided machine setting conditions, and using it as a magnetic recording medium substrate Ni-P-plated aluminum alloy A polished product of the substrate was obtained.

The setting conditions for the double-sided machine are shown below.
<Setting conditions of double-sided machine>
Double-sided processing machine: Speed Farm Co., Ltd., 9B type double-sided processing machine Processing pressure: 9.8kPa
Polishing pad: “H9900S” (trade name) manufactured by Fujibow Corporation
Plate rotation speed: 50r / min
Polishing liquid composition supply flow rate: 100ml / min
Polishing time: 5min
Number of substrates loaded: 10

[Polishing speed]
Weigh each substrate before and after polishing (measured by “BP-210S” manufactured by Sartorius) to determine the change in the weight of each substrate. The average value of 10 substrates is taken as the reduction amount and divided by the polishing time. The value was used as the weight reduction rate. The weight reduction rate was introduced into the following equation and converted to a polishing rate (μm / min).
Weight reduction rate (g / min) = {weight before polishing (g) −weight after polishing (g)}
/ Polishing time (min)
Polishing rate (μm / min) = Weight reduction rate (g / min) / Substrate single side area (mm ² )
/ Ni-P plating density (g / cm ³ ) × 10 ⁶

  As shown in Table 1, the polishing liquid compositions obtained from the polishing liquid kits of Comparative Examples 1 to 4 have a polishing rate after storage at 60 ° C. When the polishing evaluation is performed immediately after preparation without storage. Whereas the polishing rate obtained from the polishing solution kits of Examples 1 to 3 is significantly lower than the polishing rate of (Reference Example 1), the polishing rate after storage at 60 ° C. is that of Reference Example 1. It can be seen that, as in the case, it is maintained with high reproducibility and high.

Examples 4 and 5 and Comparative Examples 5 to 7 (however, Examples 4 and 5 are reference examples)
A polishing composition was obtained in the same manner as in Example 1 except that the polishing liquid kits of Examples 4 and 5 and Comparative Examples 5 to 7 having the configurations shown in Table 2 were used, and the polishing evaluation of the polishing liquid composition was performed. Then, the polishing rate of the polishing composition of Reference Example 2 was used as a reference value 1, and the relative values of the polishing rates of the polishing compositions of Examples and Comparative Examples were determined. The results are shown in Table 2. The polishing composition of Reference Example 2 was prepared in the same manner as the polishing composition of Reference Example 1 except that the composition shown in Table 2 was used.

  As shown in Table 2, the polishing liquid compositions obtained from the polishing liquid kits of Comparative Examples 5 to 7 have a polishing rate after storage at 60 ° C. When the polishing evaluation is performed immediately after preparation without storage The polishing liquid composition obtained from the polishing liquid kits of Examples 4 and 5 has a polishing speed after storage at 60 ° C. of Reference Example 2 while it is significantly lower than the polishing speed of (Reference Example 2). As in the case, it can be seen that the high level is maintained with good reproducibility.

Example 6 (Reference Example) and Comparative Examples 8 to 11
A polishing composition was obtained in the same manner as in Example 1 except that the polishing liquid kits of Example 6 and Comparative Examples 8 to 11 having the configurations shown in Table 3 were used, and polishing evaluation of the polishing liquid composition was performed. With the polishing rate of the polishing composition of Reference Example 3 as the reference value 1, the relative values of the polishing rates of the polishing compositions of Examples and Comparative Examples were determined. The results are shown in Table 3. The polishing composition of Reference Example 3 was prepared in the same manner as the polishing composition of Reference Example 1 except that the composition shown in Table 3 was used.

  As shown in Table 3, when the polishing liquid compositions obtained from the polishing liquid kits of Comparative Examples 8 to 11 were subjected to polishing evaluation immediately after preparation without preparation at a polishing rate after storage at 60 ° C. The polishing liquid composition obtained from the polishing liquid kit of Example 6 is significantly lower than the polishing speed of (Reference Example 3), while the polishing speed after storage at 60 ° C. is the same as that of Reference Example 3. Similarly, it can be seen that the high level is maintained with good reproducibility.

Examples 7-18 and Comparative Examples 12-18 (However, Examples 7-10, 13, 14, 16-18 are reference examples)
A polishing composition was obtained in the same manner as in Example 1 except that the polishing liquid kits of Examples 7 to 18 and Comparative Examples 12 to 18 having the configurations shown in Tables 4 and 5 were used. Polishing of the polishing liquid composition The evaluation was performed, and the polishing rate of the polishing composition of Reference Example 4 was used as a reference value 1, and the relative values of the polishing rates of the polishing compositions of Examples and Comparative Examples were determined. The results are shown in Tables 4 and 5. The polishing composition of Reference Example 4 was prepared in the same manner as the polishing composition of Reference Example 1 except that the composition shown in Table 5 was used.

  As shown in the results of Tables 4 and 5, the polishing liquid compositions obtained from the polishing liquid kits of Comparative Examples 12 to 18 were subjected to polishing evaluation immediately after preparation without storage at a polishing rate after storage at 60 ° C. In contrast, the polishing rate obtained from the polishing solution kits of Examples 7 to 18 was significantly lower than the polishing rate in Reference Example 4 (Reference Example 4). As in the case of No. 4, it can be seen that the high level is maintained with good reproducibility.

  The magnetic disk polishing liquid kit of the present invention can be suitably used for production of a magnetic disk substrate such as a high-quality hard disk.

Claims (3)

A slurry (A) composed of alumina , sulfuric acid and / or a salt thereof, water , an additive liquid (D) containing an inorganic acid selected from sulfuric acid, sulfurous acid and amidosulfuric acid, and hydrogen peroxide , organic sulfonic acids, A magnetic disk polishing liquid kit comprising at least an acid solution (c) containing an organic acid selected from organic phosphonic acids and polyvalent carboxylic acids , each of which is contained in a separate container , wherein the slurry ( In A), the content of sulfuric acid in the case of containing sulfuric acid is 0.01 to 3% by weight, and the content of sulfuric acid in the case of containing a salt of sulfuric acid is 0.05 to 15% by weight. . At least a slurry (A) made of alumina , sulfuric acid and / or a salt thereof, water , an inorganic acid selected from sulfuric acid, sulfurous acid and amidosulfuric acid, and hydrogen peroxide, each contained in a separate container. A mixed liquid obtained by mixing the additive liquid (D) and an acid liquid (c) containing an organic acid selected from organic sulfonic acids, organic phosphonic acids and polyvalent carboxylic acids is used as a magnetic disk substrate and a polishing cloth. And polishing the magnetic disk substrate , wherein the slurry (A) has a content of 0.01 to 3% by weight when sulfuric acid is contained, and contains a salt of sulfuric acid. A polishing method, wherein the content is 0.05 to 15% by weight . A method of manufacturing a polished magnetic disk substrate having the following steps:
(1) At least an inorganic acid and hydrogen peroxide selected from a slurry (A) made of alumina , sulfuric acid and / or a salt thereof, water , sulfuric acid, sulfurous acid and amidosulfuric acid, each contained in a separate container. A step of preparing a polishing liquid by mixing an additive liquid (D) containing an acid solution (c) containing an organic acid selected from organic sulfonic acids, organic phosphonic acids and polyvalent carboxylic acids, wherein In the slurry (A), the content when containing sulfuric acid is 0.01 to 3% by weight, and the content when containing a salt of sulfuric acid is 0.05 to 15% by weight.
(2) a step of pressing the magnetic disk substrate against the polishing cloth of the polishing platen and pressurizing; and (3) supplying the polishing liquid prepared in step (1) between the magnetic disk substrate and the polishing cloth, The process of polishing the magnetic disk substrate by moving the polishing platen.