阅读说明：本技术 铝制磁盘的制造方法 (Method for manufacturing aluminum magnetic disk ) 是由 安藤庆介 于 2017-12-27 设计创作，主要内容包括：本发明在一个方案中提供一种铝制磁盘的制造方法,其提高磁性层形成前的基板表面的平滑性,能够高成品率地获得能够介质化的硬盘用基板。本发明在一个方案中涉及一种铝制磁盘的制造方法,其包括下述工序1及2,工序1：使含有具有至少1个下述式(I)所示的结构且分子量为50以上且100,000以下的化合物(成分A)的组合物与镀Ni-P的铝合金基板的基板表面接触的工序；工序2：在工序1中所得的基板上形成磁性层的工序。<Image he="282" wi="700" file="DDA0002555331440000011.GIF" imgContent="drawing" imgFormat="GIF" orientation="portrait" inline="no"></Image>(In one aspect, the present invention provides a method for manufacturing an aluminum magnetic disk, which can improve the smoothness of the substrate surface before the formation of a magnetic layer and can obtain a substrate for a hard disk that can be made intermediate in high yield. In one aspect, the present invention relates to a method for manufacturing an aluminum magnetic disk, including the following steps 1 and 2, step 1: a step in which a composition containing a compound (component A) having at least 1 structure represented by the following formula (I) and a molecular weight of 50 or more and 100,000 or less is brought into contact with the substrate surface of an Ni-P-plated aluminum alloy substrate; and a step 2: and a step of forming a magnetic layer on the substrate obtained in the step 1.)

1. A method for manufacturing an aluminum magnetic disk, comprising the following steps 1 and 2:

step 1: a step of bringing a composition containing a component A, which is a compound having at least 1 structure represented by the following formula (I) and having a molecular weight of 50 or more and 100,000 or less, into contact with the substrate surface of an Ni-P plated aluminum alloy substrate;

and a step 2: a step of forming a magnetic layer on the substrate obtained in the step 1,

in the formula (I), R¹Is at least 1 selected from ethylene, propylene and isopropylene, and represents a bond.

2. The method of manufacturing an aluminum magnetic disk according to claim 1, wherein the step 1 is a step of bringing the composition containing the component A into contact with a substrate, rinsing with an aqueous solvent, and drying.

3. The method for producing an aluminum magnetic disk according to claim 1 or 2, wherein the composition containing component a is an aqueous solution.

4. The method for producing an aluminum magnetic disk according to any of claims 1 to 3, wherein the Ni-P plated aluminum alloy substrate is a Ni-P plated aluminum alloy substrate having a reduced smoothness as compared with that immediately after polishing.

5. The method for producing an aluminum magnetic disk according to any of claims 1 to 4, wherein the composition containing component A is a leveler composition for smoothing the surface of a substrate on which a magnetic layer is to be formed.

6. The method for producing an aluminum magnetic disk according to any of claims 1 to 5, wherein the component A is at least 1 selected from the group consisting of a compound represented by the following formula (II) and polyethyleneimine,

in the formula (II), R¹Is at least 1 selected from ethylene, propylene and isopropylene, R²And R³Each independently selected from the group consisting of hydrogen, methyl, ethyl, hydroxymethyl, hydroxyethyl, hydroxypropyl, aminoethyl, aminopropyl and- (CH)₂)₂NH(CH₂)₂NH₂At least 1 of the groups.

7. The method for producing an aluminum magnetic disk according to any of claims 1 to 6, wherein the composition containing component A has a pH of 9 or more and 14 or less.

8. The method for producing an aluminum magnetic disk according to any of claims 1 to 7, wherein the composition containing component A has a pH of 11.8 or more and 14 or less.

9. The method for producing an aluminum magnetic disk according to any of claims 1 to 8, wherein the composition containing component A further contains a chelating agent, component B.

10. The method for producing an aluminum magnetic disk according to any of claims 1 to 9, wherein the composition containing component a contains substantially no at least 1 selected from the group consisting of a compound having an aromatic sulfonic acid group, an anionic surfactant, a nonionic surfactant, and an abrasive.

11. The method for producing an aluminum magnetic disk according to any of claims 1 to 10, wherein the composition containing component A further comprises component B which is a chelating agent, component C which is water, and component D which is an alkaline agent other than component A,

the composition comprises a component A, a component B, a component C and a component D.

12. The method for producing an aluminum magnetic disk according to any of claims 1 to 11, wherein the substrate in the step 1 is a substrate having an oxidized substrate surface.

13. The method for producing an aluminum magnetic disk according to any of claims 1 to 12, wherein the substrate in the step 1 is a substrate which has been polished for 1 hour or more.

14. The method for manufacturing an aluminum magnetic disk according to any of claims 1 to 13, wherein step 1 is performed immediately before step 2.

15. The method for producing an aluminum magnetic disk according to any of claims 1 to 14, wherein the step 1 and the step 2 are successively performed in this order.

16. A smoothing agent composition for smoothing the surface of a substrate on which a magnetic layer is to be formed,

which contains a component A which is a compound having at least 1 structure represented by the following formula (I) and having a molecular weight of 50 or more and 100,000 or less,

in the formula (I), R¹Is at least 1 selected from ethylene, propylene and isopropylene, and represents a bond.

17. A smoothing method for smoothing a surface of a substrate using the smoothing agent composition of claim 16.

Technical Field

The present invention relates to a method for producing an aluminum magnetic disk, a smoothing agent composition and a smoothing method.

Background

In recent years, personal computers and various electronic devices have been required to be capable of handling large data such as moving images and audio, and large-capacity information recording devices have been required. As a result, the demand for higher recording density of information recording media has increased year by year. In order to cope with this, the adoption and mass production of the perpendicular magnetic recording system have been advanced in the hard disk. In the perpendicular magnetic recording system, smoothness of the substrate surface is required to a higher level than that of a conventional substrate for an information recording medium (hereinafter, also referred to as a "substrate for a hard disk"). This is because the magnetic material has to be miniaturized due to the increase in recording density, and the recording/reading head needs to be brought closer to the substrate for a hard disk in accordance with the decrease in magnetic force of the magnetic material due to the miniaturization, and the small unevenness on the substrate surface, which has not been a problem in the past, affects the decrease in reliability of the information recording apparatus or the increase in defect rate. Therefore, the surface of the substrate for hard disks is required to have high smoothness and high cleanliness.

Examples of the material used for the substrate for hard disks include aluminum and glass having a nickel-phosphorus plated surface. Aluminum is more processable than glass, and therefore, can be produced at a lower cost, and is widely used.

Patent document 1 discloses a cleaning agent composition for a substrate for a hard disk having a Ni — P-containing layer, which contains a specific acrylic copolymer and/or a salt thereof (component (a)), polyamine (component (B)), and water (component (C)), and which contains substantially no nonionic surfactant, wherein the content of the component (B) in the total weight of components other than the component (C) is 30 to 95% by weight, and the weight ratio of the component (a) to the component (B) { component (a)/component (B) } is 0.04 to 0.8.

Patent document 2 discloses a cleaning agent for a magnetic disk substrate, which contains an anionic surfactant (a) and/or a chelating agent (B), has a content of alkali metal cations of 100ppm or less based on the weight of the cleaning agent for a magnetic disk substrate, and is used in a scrubbing cleaning step in which a liquid obtained by diluting the cleaning agent to 5% by weight has a pH value of 7.0 to 12.5 at 25 ℃.

Patent document 3 discloses a cleaning agent composition for a hard disk substrate, which is characterized in that: contains 0.01 to 5.00 mass% of the component (A): an alkali metal hydroxide, 0.10 to 20.00 mass% of component (B): 1-hydroxyethane-1, 1-diphosphonic acid and/or a salt thereof, 0.05 to 10.00 mass% of component (C): polyoxyethylene alkyl ether sulfate, the content of the surfactant being less than 1.00 mass%.

Patent document 4 discloses a cleaning liquid for an electronic material substrate, which is characterized in that: the cleaning solution for the electronic material substrate comprises water-soluble amine (A), the pH value of the cleaning solution at 25 ℃ is 10.5-11.6, and the condition that the concentration of the water-soluble amine is more than or equal to 0.61)/the pH value of the cleaning solution is more than or equal to 0.059 is satisfied.

Disclosure of Invention

Problems to be solved by the invention

In order to obtain high smoothness of the substrate surface, the substrate surface is precisely polished in a polishing step, but the following may be used: even if the substrate is smooth immediately after polishing, the smoothness is reduced by adhesion of foreign matters and oxidation of the substrate surface during storage or transportation until a magnetic layer is formed on the substrate surface (hereinafter also referred to as "medium").

In view of the above, one aspect of the present invention is to provide a method for manufacturing an aluminum magnetic disk, which can improve the smoothness of the substrate surface before the magnetic layer is formed, and can obtain a substrate for a hard disk that can be made intermediate with high yield.

Means for solving the problems

In one aspect, the present invention relates to a method for manufacturing an aluminum magnetic disk, including the following steps 1 and 2:

step 1: a step in which a composition containing a compound (component A) having at least 1 structure represented by the following formula (I) and a molecular weight of 50 or more and 100,000 or less is brought into contact with the substrate surface of an Ni-P-plated aluminum alloy substrate;

and a step 2: a step of forming a magnetic layer on the substrate obtained in step 1;

[ chemical formula 1]

In the formula (I), R¹Is at least 1 selected from ethylene, propylene and isopropylene, and represents a bond.

The present invention relates to a smoothing agent composition, which is used for smoothing the surface of a substrate for forming a magnetic layer,

the smoothing agent composition contains a compound (component A) having at least 1 structure represented by formula (I) and having a molecular weight of 50 or more and 100,000 or less;

[ chemical formula 2]

In the formula (I), R¹Is at least 1 selected from ethylene, propylene and isopropylene, and represents a bond.

In other aspects, the present invention relates to a smoothing method for smoothing a surface of a substrate using the smoothing agent composition of the present invention.

ADVANTAGEOUS EFFECTS OF INVENTION

According to one aspect of the present invention, smoothness of the substrate surface before the magnetic layer is formed is improved, and a substrate for a hard disk that can be made intermediate in quality can be obtained with high yield.

Detailed Description

The invention is based on the following insight: by smoothing the substrate surface having reduced smoothness as compared with the substrate surface immediately after polishing using a smoothing agent composition containing a specific compound (component a), the smoothness of the substrate surface before formation of the magnetic layer can be improved, and a substrate for a hard disk that can be made intermediate can be obtained with high yield.

That is, the present invention relates to a method for manufacturing an aluminum magnetic disk (hereinafter, also referred to as "manufacturing method of the present invention"), which includes, in one embodiment, the following steps 1 and 2:

step 1: a step of bringing a composition (hereinafter also referred to as "the composition of the present invention") containing a compound (component a) having at least 1 structure represented by the formula (I) and having a molecular weight of 50 or more and 100,000 or less into contact with the substrate surface of the Ni — P plated aluminum alloy substrate;

and a step 2: and a step of forming a magnetic layer on the substrate obtained in the step 1.

The details of the mechanism for expressing the effect of the present invention are not clear, and are presumed as follows.

Unlike a glass substrate, a nickel-phosphorus amorphous layer plated on the surface of an aluminum hard disk tends to be oxidized by reaction with oxygen in the air when it comes into contact with the air, and the surface tends to be uneven due to unevenness of the nickel-phosphorus ratio on the surface or the influence of unevenness, thereby reducing surface smoothness.

In general, a substrate for a hard disk can be manufactured by subjecting a base material serving as a base of the substrate for a hard disk to a shape processing step, a rough polishing step, a finish polishing step, and the like. The cleaning step may not be included between the steps. The substrate for a hard disk is completely dried at a time after the finish polishing step or the final cleaning step, and then, in the magnetic disk manufacturing step, a magnetic layer is formed on the surface of the substrate to form a magnetic hard disk (magnetic disk). In general, since the polishing step and the cleaning step are performed in different factories from the magnetic disk manufacturing step, the substrate for hard disks obtained after the finish polishing step or the final cleaning step is transported to the magnetic disk manufacturing step through a storage and/or transport step.

The substrate surface of a hard disk substrate immediately after polishing (for example, a hard disk substrate obtained after a finish polishing step or a final cleaning step) has high smoothness, but the substrate surface is oxidized by oxygen in the air to form an uneven oxide film during storage and/or transportation in a magnetic disk manufacturing step, and the smoothness may be reduced. In addition, smoothness may be reduced by foreign matter such as dust adhering to the sheet during storage or transportation. In this way, the substrate transported to the magnetic disk manufacturing process tends to have reduced smoothness as compared with the substrate surface immediately after polishing. If the smoothness of the substrate surface is reduced, it is difficult to form a magnetic layer uniformly in the magnetic disk manufacturing process, and the recording density as a substrate for a hard disk is reduced, and further, the magnetic head collides with the substrate due to the influence of the unevenness, and the recording and writing are not completed as defective products, thereby reducing the production yield.

In contrast, in the present invention, the nitrogen atom, particularly the amino group, of the specific component a contained in the composition reduces the nickel oxide formed on the substrate surface, and dissolves the nickel oxide in the composition. It is thus presumed that the oxide film on the substrate surface is removed, and a smooth surface is regenerated or formed, which is one of the causes of the reduction in the smoothness of the substrate surface before the magnetic layer is formed.

Further, since the component a has 2 or more nitrogen atoms, it is considered that the nitrogen atoms are coordinately bonded to a metal such as nickel, which is a polyvalent metal ion, to form a chelate having a cyclic structure such as a 5-membered ring or a 6-membered ring. It is considered that since the chelate structure is stable if it is a cyclic structure such as a 5-membered ring or a 6-membered ring, dissolution of nickel oxide is promoted, and the oxide film is more effectively removed.

Further, it is presumed that the foreign substance adsorption component a such as dust adhering to the substrate surface, which is one of the causes of the reduction in smoothness of the substrate surface before the magnetic layer formation, causes charge repulsion between the substrate surface and the foreign substance, and removes the foreign substance from the substrate surface.

When the composition of the present invention further contains a chelating agent (component B), it is considered that the reduction of the nickel oxide can be more effectively caused, or dissolved nickel can be chelated and stably held in the composition, and the removal of foreign matter from the substrate surface can be improved.

However, the present invention is not limited to these mechanisms for explanation.

< composition >

[ component A ]

The component a contained in the composition of the present invention is a compound having at least 1 structure represented by the following formula (I) and having a molecular weight of 50 or more and 100,000 or less. The component A may be used alone or in combination of 2 or more.

[ chemical formula 3]

In the formula (I), R¹Is at least 1 selected from ethylene, propylene and isopropylene, and represents a bond. In one or more embodiments, denotes a bond to other constituent or other atoms. Examples of the other structure include an organic group. Examples of the other atoms include at least 1 selected from a hydrogen atom, a halogen atom, and a metal. Sometimes also referred to as a bonding site, or bonding site.

The number of nitrogen atoms in the molecule of the component a is preferably 2 or more from the viewpoint of improving smoothness, and 1300 or less, more preferably 1000 or less, further preferably 100 or less, further preferably 10 or less, and further preferably 4 or less from the viewpoint of solubility of nickel oxide.

The number of amino groups in the molecule of the component a is preferably 1 or more, more preferably 2 or more, from the viewpoint of improving smoothness, and is preferably 500 or less, more preferably 30 or less, and even more preferably 10 or less, from the viewpoint of solubility of nickel oxide.

From the viewpoint of improving smoothness, the component a is preferably at least 1 selected from the group consisting of the compound represented by the formula (II) and polyethyleneimine.

[ chemical formula 4]

In the formula (II), R¹Is at least 1 selected from ethylene, propylene and isopropylene, R²And R³Are each independently selected from the group consisting of hydrogen, methyl, ethyl, hydroxymethyl, hydroxyethyl, hydroxypropyl, aminoethyl, aminopropyl and- (CH)₂)₂NH(CH₂)₂NH₂At least 1 of the groups.

Examples of the compound represented by the formula (II) as the component a include: amino alcohols such as N- (β -aminoethyl) ethanolamine and N- (β -aminoethyl) isopropanolamine; amines such as ethylenediamine, N-ethylethylenediamine, 1, 2-propylenediamine, 1, 3-propylenediamine, N-bis (aminopropyl) methylamine, diethylenetriamine, and triethylenetetramine.

In one or more embodiments, the component a is preferably at least 1 selected from N- (β -aminoethyl) ethanolamine, N- (β -aminoethyl) isopropanolamine, ethylenediamine, N-ethylethylenediamine, 1, 2-propylenediamine, 1, 3-propylenediamine, diethylenetriamine, triethylenetetramine and polyethyleneimine, more preferably at least 1 selected from N- (β -aminoethyl) ethanolamine, N- (β -aminoethyl) isopropanolamine, ethylenediamine, N-ethylethylenediamine, 1, 2-propylenediamine, diethylenetriamine, triethylenetetramine and polyethyleneimine, still more preferably at least 1 selected from N- (β -aminoethyl) ethanolamine, N- (β -aminoethyl) isopropanolamine, At least 1 of ethylenediamine, N-ethylethylenediamine, 1, 2-propylenediamine, and diethylenetriamine.

In one or more other embodiments, the component a is preferably at least 1 selected from N- (β -aminoethyl) ethanolamine, N- (β -aminoethyl) isopropanolamine, ethylenediamine, N-ethylethylenediamine, 1, 2-propylenediamine, diethylenetriamine, triethylenetetramine and polyethyleneimine, more preferably at least 1 selected from N- (β -aminoethyl) ethanolamine, N- (β -aminoethyl) isopropanolamine, ethylenediamine, N-ethylethylenediamine and 1, 2-propylenediamine, still more preferably at least 1 selected from N- (β -aminoethyl) ethanolamine, N- (β -aminoethyl) isopropanolamine, ethylenediamine and N-ethylethylenediamine, more preferably N- (. beta. -aminoethyl) ethanolamine and/or N- (. beta. -aminoethyl) isopropanolamine.

In one or more other embodiments, the component a is preferably at least 1 selected from N- (β -aminoethyl) ethanolamine, N- (β -aminoethyl) isopropanolamine, ethylenediamine, N-ethylethylenediamine, 1, 2-propylenediamine, diethylenetriamine, triethylenetetramine and polyethyleneimine, more preferably at least 1 selected from N- (β -aminoethyl) isopropanolamine, N-ethylethylenediamine, 1, 2-propylenediamine and diethylenetriamine, even more preferably N- (β -aminoethyl) isopropanolamine and/or 1, 2-propanediamine.

The molecular weight of the component a is 50 or more from the viewpoint of improving smoothness, and is 100,000 or less, preferably 70,000 or less, more preferably 10,000 or less, further preferably 2,000 or less, and further preferably 1,000 or less from the viewpoint of solubility of nickel oxide.

When the component a is polyethyleneimine, the weight average molecular weight of the component a is preferably 50 or more from the viewpoint of improving smoothness, and is preferably 70,000 or less, more preferably 10,000 or less, and even more preferably 2,000 or less from the viewpoint of solubility of nickel oxide. In the present invention, the weight average molecular weight can be measured by a Gel Permeation Chromatography (GPC) under the following conditions using a liquid chromatography (L-6000 high performance liquid chromatography manufactured by Hitachi, Ltd.).

< GPC conditions >

Sample solution: adjusted to a concentration of 0.5g/100mL

A detector: shodex RI SE-61 differential refractive index detector

Pipe column: obtained by connecting G4000PWXL and G2500PWXL manufactured by Tosoh Corp

Eluent: 0.2M phosphate buffer/acetonitrile 90/10 (volume ratio)

Temperature of the pipe column: 40 deg.C

Flow rate: 1.0mL/min

Sample liquid injection amount: 20 μ L

Standard polymer: monodisperse polyethylene glycols of known molecular weight

The content of the component a in the use of the composition of the present invention is, in one or more embodiments, preferably 0.01% by mass or more, more preferably 0.03% by mass or more, and further preferably 0.1% by mass or more, from the viewpoint of obtaining smoothness in a short time, and is preferably 1.0% by mass or less, more preferably 0.5% by mass or less, further preferably 0.3% by mass or less, and further preferably 0.2% by mass or less, from the same viewpoint. Further, the content of the component a in the use of the composition of the present invention is preferably 0.01% by mass or more and 1.0% by mass or less, more preferably 0.03% by mass or more and 0.5% by mass or less, further preferably 0.1% by mass or more and 0.3% by mass or less, and further preferably 0.1% by mass or more and 0.2% by mass or less, from the same viewpoint.

In another embodiment or embodiments, the content of the component a in the use of the composition of the present invention is preferably 0.01% by mass or more, more preferably 0.03% by mass or more, and still more preferably 0.05% by mass or more, from the viewpoint of obtaining a smoother substrate surface, and is preferably 1.0% by mass or less, more preferably 0.5% by mass or less, still more preferably 0.3% by mass or less, and still more preferably 0.1% by mass or less, from the same viewpoint. From the same viewpoint, the content of the component a in the use of the composition of the present invention is preferably 0.01% by mass or more and 1.0% by mass or less, more preferably 0.03% by mass or more and 0.5% by mass or less, still more preferably 0.05% by mass or more and 0.3% by mass or less, and still more preferably 0.05% by mass or more and 0.1% by mass or less.

In the present invention, the "content of each component in the use of the composition" refers to the content of each component of the composition used in the step 1 in one or more embodiments.

[ component B: chelating agent ]

From the viewpoint of improving smoothness, the composition of the present invention may contain a chelating agent (component B). The component B may be used alone or in combination of 2 or more.

Examples of the chelating agent as the component B include chelating agents selected from the group consisting of aldonic acids such as gluconic acid and glucoheptonic acid; aminocarboxylic acids such as ethylenediaminetetraacetic acid and diethylenetriaminepentaacetic acid; hydroxycarboxylic acids such as citric acid and malic acid; phosphonic acids such as 1-hydroxyethylidene-1, 1-diphosphonic acid; thioacids such as thioglycolic acid; amino acids such as glycine; and salts thereof, and acetylacetone. Examples of the salt include: alkali metals, alkaline earth metals, ammonium, and the like.

In one or more embodiments, from the viewpoint of improving smoothness, the component B is preferably at least 1 selected from the group consisting of gluconic acid, ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, citric acid, 1-hydroxyethylidene-1, 1-diphosphonic acid, thioglycolic acid, glycine and a salt thereof, and acetylacetone, more preferably at least 1 selected from the group consisting of gluconic acid, ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, 1-hydroxyethylidene-1, 1-diphosphonic acid, thioglycolic acid, glycine and a salt thereof, and further preferably at least 1 selected from the group consisting of ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, thioglycolic acid, glycine and a salt thereof.

In one or more other embodiments, from the viewpoint of obtaining smoothness in a short time, the component B is preferably at least 1 selected from the group consisting of gluconic acid, ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, citric acid, 1-hydroxyethylidene-1, 1-diphosphonic acid, thioglycolic acid, glycine and salts thereof, and acetylacetone, more preferably at least 1 selected from the group consisting of gluconic acid, ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, 1-hydroxyethylidene-1, 1-diphosphonic acid, thioglycolic acid, glycine and salts thereof, and still more preferably at least 1 selected from the group consisting of ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, glycine and salts thereof.

In one or more other embodiments, the component B is preferably at least 1 selected from the group consisting of gluconic acid, ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, citric acid, 1-hydroxyethylidene-1, 1-diphosphonic acid, thioglycolic acid, glycine and salts thereof, and acetylacetone, more preferably at least 1 selected from the group consisting of gluconic acid, ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, citric acid, thioglycolic acid, glycine and salts thereof, and further preferably at least 1 selected from the group consisting of ethylenediaminetetraacetic acid, thioglycolic acid, glycine and salts thereof, from the viewpoint of obtaining a smoother substrate surface.

The content of the component B in the use of the composition of the present invention is preferably 0.001% by mass or more, more preferably 0.005% by mass or more, and even more preferably 0.01% by mass or more from the viewpoint of improving smoothness and reducing the load of drainage treatment, and is preferably 0.2% by mass or less, more preferably 0.1% by mass or less, even more preferably 0.05% by mass or less, and even more preferably 0.02% by mass or less from the viewpoint of improving smoothness and reducing the load of drainage treatment. From the same viewpoint, the content of the component B in the use of the composition of the present invention is preferably 0.001 mass% or more and 0.2 mass% or less, more preferably 0.005 mass% or more and 0.1 mass% or less, still more preferably 0.01 mass% or more and 0.05 mass% or less, and still more preferably 0.01 mass% or more and 0.02 mass% or less.

[ component C: water ]

The composition of the present invention may further contain water (component C). The water as the component C is not particularly limited as long as it can act as a solvent, and examples thereof include ultrapure water, pure water, ion-exchanged water, and distilled water, and the like, and ultrapure water, pure water, or ion-exchanged water is preferable, and ultrapure water is more preferable. Pure water and ultrapure water can be obtained by, for example, introducing tap water into activated carbon, performing ion exchange treatment, and further distilling, and irradiating a specific ultraviolet germicidal lamp or introducing a filter as required.

The content of the component C in the use of the composition of the present invention is preferably 90% by mass or more, more preferably 95% by mass or more, and still more preferably 99% by mass or more, from the viewpoint of improving smoothness and stabilizing the composition, and is preferably 99.99% by mass or less, more preferably 99.9% by mass or less, and still more preferably 99.8% by mass or less from the same viewpoint.

[ component D: alkaline agent

The composition of the present invention may further contain an alkaline agent (component D) other than the component A. The component D may be used alone or in combination of two or more.

Examples of the alkaline agent as the component D include compounds capable of imparting alkalinity to the composition of the present invention and compounds capable of adjusting the pH of the composition of the present invention within the above-described range, and examples thereof include inorganic alkaline agents and organic alkaline agents. Examples of the inorganic alkaline agent as the component D include: ammonia; alkali metal hydroxides such as potassium hydroxide and sodium hydroxide; and the like. Examples of the organic alkaline agent as the component D include hydroxyalkylamine and quaternary ammonium salt. Examples of hydroxyalkylamines include: monoethanolamine, diethanolamine, triethanolamine, methylethanolamine, methyldiethanolamine, monopropanolamine, dipropanolamine, tripropanolamine, methylpropanolamine, and methyldipranolamine. Examples of the quaternary ammonium salt include tetramethylammonium hydroxide and choline.

The component D is preferably at least 1 selected from the group consisting of an alkali metal hydroxide, a hydroxyalkyl amine and a quaternary ammonium salt from the viewpoint of improving smoothness, more preferably an alkali metal hydroxide from the viewpoint of reducing the load of wastewater treatment, and still more preferably at least 1 selected from the group consisting of potassium hydroxide and sodium hydroxide.

The content of the component D in the use of the composition of the present invention may be adjusted to a pH value described later.

[ other ingredients ]

The composition of the present invention may contain the components A to D, and may further contain other components except the components A to D within a range not to impair the effects of the present invention. As other components, there may be mentioned: anionic polymers, nonionic surfactants, solubilizing agents, antioxidants, preservatives, defoamers, antimicrobials, and the like. The content of other components in the use of the composition of the present invention is preferably 0% by mass or more and 2.0% by mass or less, more preferably 0% by mass or more and 1.5% by mass or less, still more preferably 0% by mass or more and 1.3% by mass or less, and still more preferably 0% by mass or more and 1.0% by mass or less.

Examples of the anionic polymer include carboxylic acid polymers. Examples of the carboxylic acid-based polymer include: and carboxylic acid-based polymers containing methacrylic acid or acrylic acid as a constituent unit, such as acrylic acid polymers, methacrylic acid polymers, maleic acid polymers, acrylic acid/methacrylic acid copolymers, acrylic acid/maleic acid copolymers, and methacrylic acid/methyl acrylate copolymers.

Examples of the nonionic surfactant include polyalkylene glycol alkyl ethers.

Examples of the dissolving agent include at least 1 selected from the group consisting of p-toluenesulfonic acid, dimethylbenzenesulfonic acid, 2-ethylhexanoic acid, and salts thereof.

The composition of the present invention may further contain an aqueous solvent (for example, an alcohol such as ethanol) as a solvent in addition to the water (component C), but it is preferable that the solvent contained in the composition of the present invention contains only water (component C).

In one or more embodiments, the compositions of the present invention may be those that do not substantially contain a polymer other than ingredient a. The content of the polymer other than the component a in the use of the composition of the present invention is preferably less than 0.1% by mass, more preferably less than 0.001% by mass, and even more preferably substantially 0% by mass.

In one or more embodiments, the compositions of the present invention may be substantially free of anionic surfactants. The content of the anionic surfactant in the use of the composition of the present invention is preferably less than 0.1% by mass, more preferably less than 0.001% by mass, and even more preferably substantially 0% by mass.

In one or more embodiments, the composition of the present invention may be one that does not substantially contain a nonionic surfactant. That is, the content of the nonionic surfactant in the use of the composition of the present invention is preferably less than 0.001% by mass, and more preferably substantially 0% by mass.

In one or more embodiments, the composition of the present invention may also be one that does not substantially contain a compound having an aromatic sulfonic acid group. That is, the content of the compound having an aromatic sulfonic acid group in the use of the composition of the present invention is preferably less than 0.001% by mass, and more preferably substantially less than 0% by mass.

In one or more embodiments, the compositions of the present invention may also be substantially free of abrasive materials. That is, the content of the abrasive in the use of the composition of the present invention is preferably less than 0.05% by mass, and more preferably substantially 0% by mass.

In one or more embodiments, the compositions of the present invention may also be aqueous solutions. The composition of the present invention is, in one or more embodiments, a smoothing agent composition for smoothing a surface of a substrate on which a magnetic layer is formed.

[ method for producing composition ]

The composition of the present invention can be produced by blending the component a, and if necessary, the component B, the component C, the component D, and other components by a known method. For example, the composition of the present invention may be prepared by blending at least component A. In the present invention, "blending" includes mixing the component A and, if necessary, the component B, the component C, the component D and other components at the same time or in an arbitrary order. In the method for producing the composition of the present invention, the amounts of the respective components may be the same as the amounts of the respective components of the composition of the present invention.

[ pH value of composition ]

From the viewpoint of improving smoothness, the pH value of the composition of the present invention when used is preferably 9 or more, more preferably 9.5 or more, further preferably 10 or more, further preferably 10.5 or more, further preferably 11.8 or more, and from the same viewpoint, is preferably 14 or less, more preferably 13 or less, further preferably 12.5 or less. More specifically, the pH value of the composition of the present invention when used is preferably 9 or more and 14 or less, more preferably 9.5 or more and 14 or less, further preferably 10 or more and 14 or less, further preferably 10.5 or more and 14 or less, further preferably 11.8 or more and 13 or less, further preferably 11.8 or more and 12.5 or less. The pH of the composition of the present invention can be adjusted, for example, using an acid or an alkaline agent (component D) other than the component a. Examples of the acid include: inorganic acids such as nitric acid, sulfuric acid, and hydrochloric acid; organic acids such as hydroxycarboxylic acids and amino acids; and the like. In the present invention, the "pH value at the time of use" refers to the pH value at 25 ℃ at the time of use of the composition, and is measured using a pH meter, and is preferably a value obtained by immersing an electrode of the pH meter in the composition for 3 minutes.

The compositions of the invention may also be manufactured as concentrates, diluted at the time of use, from the standpoint of storage and transport. The concentrate of the composition is preferably a concentrate having a dilution ratio of 3 times or more from the viewpoint of storage and transportation, and is preferably a concentrate having a dilution ratio of 200 times or less from the viewpoint of storage stability. The concentrate of the composition can be diluted with water (component C) so that the respective components become the above-mentioned contents at the time of use. Further, the concentrate of the composition can be used by adding each component separately at the time of use. In the present invention, the term "at the time of use" of the concentrate of the composition means a state in which the concentrate of the composition is diluted.

The pH of the concentrate of the composition of the present invention is preferably 9 or more, more preferably 10 or more, further preferably 11 or more, and still more preferably 12 or more from the viewpoint of improving the smoothness after dilution, and is preferably 14 or less, more preferably 13.8 or less, and still more preferably 13.5 or less from the same viewpoint. The pH of the concentrate of the composition of the present invention can be measured by the same method as the pH of the composition of the present invention described above.

[ smoothed substrate ]

In one or more embodiments, the composition of the present invention is used for smoothing the surface of a substrate having reduced smoothness as compared to the substrate immediately after polishing. In one or more embodiments, the compositions of the present invention are used to smooth the surface of substrates that are stored and/or transported after polishing. Further, the period required for storage and/or transportation is not constant. In one or more embodiments, the composition of the present invention is used for surface smoothing of a substrate on which a magnetic layer is formed. In one or more embodiments, the compositions of the present invention are preferably used for surface smoothing of substrates for substrate surface oxidation. In one or more embodiments, the composition of the present invention is preferably used for surface smoothing of a substrate after 1 hour or more after polishing. The elapsed time after polishing is preferably 1 hour or more, more preferably 2 hours or more, further preferably 5 hours or more, further preferably 12 hours or more, further preferably 20 hours or more, further preferably 1 day or more, further preferably 2 days or more, and further preferably 5 days or more.

The substrate may be an Ni-P plated aluminum alloy substrate. In the present invention, the phrase "Ni-P plated aluminum alloy substrate having reduced smoothness as compared with that immediately after polishing" refers to, in one or more embodiments, a Ni-P plated aluminum alloy substrate which is stored and/or transported after polishing.

As described above, in one or more embodiments, although the polished substrate may have a reduced smoothness of the substrate surface during storage and/or transportation, a substrate having an improved surface smoothness can be obtained by using the composition of the present invention. Accordingly, in other aspects, the present invention is directed to a smoothing method for smoothing a surface of a substrate using the composition of the present invention.

In the present invention, the "Ni-P plated aluminum alloy substrate" refers to an aluminum alloy substrate obtained by grinding the surface of an aluminum alloy substrate and then subjecting the aluminum alloy substrate to electroless Ni-P plating. The shape of the Ni — P plated aluminum alloy substrate includes, for example: the disk-like shape is preferable among those having a flat surface such as a disk-like shape, a plate-like shape, a flat plate-like shape, and a prism-like shape, and those having a curved surface such as a lens. In the case of a disk-shaped substrate, the outer diameter is about 30 to 97mm and the thickness is about 0.5 to 2 mm.

In the production method of the present invention, before the magnetic layer forming step, the surface of the substrate on which the magnetic layer is to be formed is smoothed using the composition of the present invention. That is, the production method of the present invention includes the following steps 1 and 2 in this order. Hereinafter, each step will be described in detail.

[ Process 1]

In one or more embodiments, step 1 in the production method of the present invention is a step of bringing the composition of the present invention into contact with an Ni — P plated aluminum alloy substrate. In one or more embodiments, step 1 is a step of smoothing the substrate surface of an Ni — P plated aluminum alloy substrate (hereinafter simply referred to as "smoothed substrate") having a reduced smoothness as compared to the substrate surface immediately after polishing, using the composition of the present invention (smoothing step).

Examples of the method for bringing the composition of the present invention into contact with a substrate to be smoothed include: a method of immersing a substrate to be smoothed in the composition of the present invention (immersion method), a method of brushing the substrate to be smoothed with the composition of the present invention (brushing method), and the like. The dipping method and/or the brushing method may be performed in the same manner as in the dipping cleaning and/or the brushing cleaning used in the ordinary cleaning step. The dipping method and the brushing method are specifically described below.

(impregnation method)

The conditions for immersing the composition into the smoothed substrate are not particularly limited. For example, the temperature of the composition is preferably 20 to 100 ℃ from the viewpoint of workability and workability. For example, the immersion time is preferably 5 seconds or more, more preferably 10 seconds or more, and further preferably 100 seconds or more from the viewpoint of improving smoothness, and is preferably 30 minutes or less, more preferably 10 minutes or less, and further preferably 5 minutes or less from the viewpoint of improving the production efficiency of the substrate. From the viewpoint of improving smoothness and promoting smoothing, it is preferable that the composition is given ultrasonic vibration. The frequency of the ultrasonic wave is, for example, preferably 20 to 2000kHz, more preferably 40 to 2000kHz, and still more preferably 100 to 1500 kHz.

(scrubbing method)

As the brushing method, from the viewpoint of improving the smoothness, it is preferable to spray the composition to which ultrasonic vibration is applied to contact the surface of the substrate to be smoothed, or to spray the composition to supply the composition onto the surface of the substrate to be smoothed, and to rub the surface to which the composition has been supplied with a brush.

Further, from the same viewpoint, the brushing method preferably sprays the composition to which the ultrasonic vibration is given, supplies the composition to the surface of the substrate to be smoothed, and rubs the surface to which the composition has been supplied with a brush.

As a means for supplying the composition onto the surface of the smoothed substrate, for example, a means such as a spray nozzle can be used. As the brush, for example, a cleaning brush used in a general cleaning process can be used, and specifically, a nylon brush, a PVA (polyvinyl alcohol) sponge brush, or the like can be used. The frequency of the ultrasonic wave may be, for example, the same as that preferably used in the above-mentioned dipping method.

In the smoothing in step 1, in addition to the above-described dipping and/or brushing method, a method similar to known cleaning such as swing cleaning, cleaning by rotation of a rotator or the like, agitation cleaning, or the like can be used. In the smoothing in step 1, in one or more embodiments, a cleaning tape is not used.

In step 1, the smoothed substrates may be smoothed one by one, or a plurality of smoothed substrates to be smoothed may be collectively smoothed at a time. The number of grooves used for smoothing may be 1 or more.

In one or more embodiments, step 1 is preferably a step of bringing the composition of the present invention into contact with a substrate to be smoothed and washing the substrate with an aqueous solvent such as water, and more preferably a step of bringing the composition of the present invention into contact with the substrate to be smoothed, washing the substrate with an aqueous solvent such as water, and drying the substrate.

[ Process 2]

Step 2 is a step of forming a magnetic layer on the substrate obtained in step 1 (magnetic layer forming step).

In step 2, the magnetic layer is formed by forming a magnetic layer including a metal thin film having a magnetic recording region on a substrate for a hard disk by a method such as sputtering. However, the magnetic layer forming step is not limited thereto. Examples of the metal material constituting the metal thin film include: alloys of cobalt with chromium, tantalum, platinum, etc., alloys of iron with platinum, etc., and the like. The magnetic layers may be formed on both main surfaces of the hard disk substrate, or may be formed on only one main surface.

In the production method of the present invention, it is preferable to perform step 1 immediately before step 2 from the viewpoint of the expression of the effects of the present invention. In the production method of the present invention, it is preferable that the steps 1 and 2 are continuously performed in this order from the viewpoint of exhibiting the effects of the present invention. In the production method of the present invention, the time from the end of step 1 to the start of step 2 is preferably 12 hours or less, more preferably 3 hours or less, and still more preferably 1 hour or less, from the viewpoint of the expression of the effects of the present invention.

[ hard disk recording device ]

By using the aluminum magnetic disk produced by the production method of the present invention as a recording medium of a hard disk recording device, a hard disk recording device with high recording density can be provided. As the recording method, a horizontal magnetic recording method, a vertical magnetic recording method, and a single magnetic recording method can be used.

The invention further relates to one or more of the following embodiments.

<1> a method for manufacturing an aluminum magnetic disk, comprising the following steps 1 and 2:

step 1: a step in which a composition containing a compound (component A) having at least 1 structure represented by the following formula (I) and a molecular weight of 50 or more and 100,000 or less is brought into contact with the substrate surface of an Ni-P-plated aluminum alloy substrate;

and a step 2: a step of forming a magnetic layer on the substrate obtained in step 1;

[ chemical formula 5]

In the formula (I), R¹Is at least 1 selected from ethylene, propylene and isopropylene, and represents a bond.

<2> the method for producing an aluminum magnetic disk according to <2>, wherein the step 1 is a step of bringing the composition containing the component A into contact with a substrate, and rinsing and drying the composition with an aqueous solvent.

<3> the method for producing an aluminum magnetic disk according to <1> or <2>, wherein the composition containing the component A is an aqueous solution.

<4> the method for producing an aluminum magnetic disk according to any of <1> to <3>, wherein the Ni-P plated aluminum alloy substrate is an Ni-P plated aluminum alloy substrate having a reduced smoothness as compared with that immediately after polishing.

<5> the method for producing an aluminum magnetic disk according to any of <1> to <4>, wherein the composition containing the component A is a leveler composition for smoothing the surface of a substrate on which the magnetic layer is formed.

<6> the method for producing an aluminum magnetic disk according to any one of <1> to <5>, wherein the number of nitrogen atoms in a molecule of component A is 2 or more.

<7> the method for producing an aluminum magnetic disk according to any one of <1> to <6>, wherein the number of nitrogen atoms in a molecule of component A is preferably 1300 or less, more preferably 1000 or less, further preferably 100 or less, further preferably 10 or less, and further preferably 4 or less.

<8> the method for producing an aluminum magnetic disk according to any one of <1> to <7>, wherein the number of amino groups in a molecule of component A is preferably 1 or more, more preferably 2 or more.

<9> the method for producing an aluminum magnetic disk according to any one of <1> to <8>, wherein the number of amino groups in a molecule of component A is preferably 500 or less, more preferably 30 or less, and still more preferably 10 or less.

<10> the method for manufacturing an aluminum magnetic disk according to any one of <1> to <9>, wherein the component A is at least 1 selected from the group consisting of a compound represented by formula (II) and polyethyleneimine;

[ chemical formula 6]

In the formula (II), R¹Is at least 1 selected from ethylene, propylene and isopropylene, R²And R³Are each independently selected from the group consisting of hydrogen, methyl, ethyl, hydroxymethyl, hydroxyethyl, hydroxypropyl, aminoethyl, aminopropyl and- (CH)₂)₂NH(CH₂)₂NH₂At least 1 of the groups.

<11> the method for producing an aluminum magnetic disk according to any one of <1> to <10>, wherein the molecular weight of component A is 50 or more and 100,000 or less, preferably 70,000 or less, more preferably 10,000 or less, further preferably 2,000 or less, and still further preferably 1,000 or less.

<12> the method for producing an aluminum magnetic disk according to any one of <1> to <11>, wherein when the component A is polyethyleneimine, the weight average molecular weight of the component A is preferably 50 or more.

<13> the method for producing an aluminum magnetic disk according to any one of <1> to <12>, wherein when the component A is polyethyleneimine, the weight average molecular weight of the component A is preferably 70,000 or less, more preferably 10,000 or less, and still more preferably 2,000 or less.

<14> the method for producing an aluminum magnetic disk according to any one of <1> to <13>, wherein the content of the component A in the use of the composition containing the component A is preferably 0.01% by mass or more, more preferably 0.03% by mass or more, and still more preferably 0.1% by mass or more.

<15> the method for producing an aluminum magnetic disk according to any one of <1> to <14>, wherein the content of the component A in the use of the composition containing the component A is preferably 1.0% by mass or less, more preferably 0.5% by mass or less, still more preferably 0.3% by mass or less, and still more preferably 0.2% by mass or less.

<16> the method for producing an aluminum magnetic disk according to any one of <1> to <15>, wherein the content of the component A in the use of the composition containing the component A is preferably 0.01% by mass or more and 1.0% by mass or less, more preferably 0.03% by mass or more and 0.5% by mass or less, still more preferably 0.1% by mass or more and 0.3% by mass or less, and still more preferably 0.1% by mass or more and 0.2% by mass or less.

<17> the method for producing an aluminum magnetic disk according to any one of <1> to <16>, wherein the content of the component A in the use of the composition containing the component A is preferably 0.01% by mass or more, more preferably 0.03% by mass or more, and still more preferably 0.05% by mass or more.

<18> the method for producing an aluminum magnetic disk according to any one of <1> to <17>, wherein the content of the component A in the use of the composition containing the component A is preferably 1.0% by mass or less, more preferably 0.5% by mass or less, still more preferably 0.3% by mass or less, and still more preferably 0.1% by mass or less.

<19> the method for producing an aluminum magnetic disk according to any one of <1> to <18>, wherein the content of the component A in the use of the composition containing the component A is preferably 0.01% by mass or more and 1.0% by mass or less, more preferably 0.03% by mass or more and 0.5% by mass or less, still more preferably 0.05% by mass or more and 0.3% by mass or less, and still more preferably 0.05% by mass or more and 0.1% by mass or less.

<20> the method for producing an aluminum magnetic disk according to any one of <1> to <19>, wherein the composition containing the component A further contains a chelating agent (component B).

<21> the method of producing an aluminum magnetic disk according to <20>, wherein the content of the component B in the use of the composition containing the component A is preferably 0.001% by mass or more, more preferably 0.005% by mass or more, and still more preferably 0.01% by mass or more.

<22> the method for producing an aluminum magnetic disk according to <20> or <21>, wherein the content of the component B in the use of the composition containing the component A is preferably 0.2% by mass or less, more preferably 0.1% by mass or less, still more preferably 0.05% by mass or less, and still more preferably 0.02% by mass or less.

<23> the method for producing an aluminum magnetic disk according to any one of <20> to <22>, wherein the content of the component B in the use of the composition containing the component A is preferably 0.001% by mass or more and 0.2% by mass or less, more preferably 0.005% by mass or more and 0.1% by mass or less, further preferably 0.01% by mass or more and 0.05% by mass or less, and further preferably 0.01% by mass or more and 0.02% by mass or less.

<24> the method for producing an aluminum magnetic disk according to any one of <1> to <23>, wherein the composition containing component A further contains water (component C).

<25> the method for producing an aluminum magnetic disk according to <24>, wherein the content of the component C in the use of the composition containing the component A is preferably 90% by mass or more, more preferably 95% by mass or more, and still more preferably 99% by mass or more.

<26> the method for producing an aluminum magnetic disk according to <24> or <25>, wherein the content of the component C in the use of the composition containing the component A is preferably 99.99% by mass or less, more preferably 99.9% by mass or less, and still more preferably 99.8% by mass or less.

<27> the method for producing an aluminum magnetic disk according to any one of <1> to <26>, wherein the composition containing component A further contains an alkaline agent (component D) other than component A.

<28> the method for producing an aluminum magnetic disk according to any one of <1> to <27>, wherein the composition containing component A has a pH value at the time of use of preferably 9 or more, more preferably 9.5 or more, further preferably 10 or more, further preferably 10.5 or more, and further preferably 11.8 or more.

<29> the method for producing an aluminum magnetic disk according to any one of <1> to <28>, wherein the pH of the composition containing component a is preferably 14 or less, more preferably 13 or less, and still more preferably 12.5 or less.

<30> the method for producing an aluminum magnetic disk according to any one of <1> to <29>, wherein the pH of the composition containing component a is preferably 9 or more and 14 or less, more preferably 9.5 or more and 14 or less, still more preferably 10 or more and 14 or less, yet more preferably 10.5 or more and 14 or less, yet more preferably 11.8 or more and 13 or less, yet more preferably 11.8 or more and 12.5 or less.

<31> the method for producing an aluminum magnetic disk according to any one of <1> to <30>, wherein the composition containing component A contains substantially no at least 1 selected from the group consisting of a compound having an aromatic sulfonic acid group, an anionic surfactant, a nonionic surfactant and an abrasive.

<32> the method for producing an aluminum magnetic disk according to any one of <1> to <31>, wherein the composition containing component A further contains a chelating agent (component B), water (component C) and an alkaline agent (component D) other than component A,

the composition comprises a component A, a component B, a component C and a component D.

<33> the method of manufacturing an aluminum magnetic disk according to any of <1> to <32>, wherein the substrate in the step 1 is a substrate having an oxidized substrate surface.

<34> the method of manufacturing an aluminum magnetic disk according to any one of <1> to <29>, wherein the substrate in the step 1 is a substrate which has been polished for 1 hour or more.

<35> the method of manufacturing an aluminum magnetic disk according to any one of <1> to <34>, which comprises performing step 1 immediately before step 2.

<36> the method for manufacturing an aluminum magnetic disk according to any one of <1> to <35>, which comprises the steps 1 and 2 being performed successively in this order.

<37> the method of manufacturing an aluminum magnetic disk according to any one of <1> to <36>, wherein the time from the end of step 1 to the start of step 2 is preferably 12 hours or less, more preferably 3 hours or less, and still more preferably 1 hour or less.

<38> a smoothing agent composition for smoothing the surface of a substrate on which a magnetic layer is formed,

the smoothing agent composition contains a compound (component A) having at least 1 structure represented by the following formula (I) and having a molecular weight of 50 or more and 100,000 or less;

[ chemical formula 7]

In the formula (I), R¹Is at least 1 selected from ethylene, propylene and isopropylene, and represents a bond.

<39> a smoothing method for smoothing the surface of a substrate using the smoothing agent composition <38 >.