JP6110715B2 - Abrasive composition for rough polishing of Ni-P plated aluminum magnetic disk substrate, method for polishing Ni-P plated aluminum magnetic disk substrate, method for manufacturing Ni-P plated aluminum magnetic disk substrate, and Ni-P Plated aluminum magnetic disk substrate - Google Patents

Description

  The present invention relates to an abrasive composition for rough polishing used for polishing a substrate or the like, a method for polishing a magnetic disk substrate, a manufacturing method, and a magnetic disk substrate.

  In polishing a magnetic disk substrate, various polishing characteristics are required to be improved in order to improve the magnetic recording density. For example, the end face shape of the magnetic disk substrate is cut more than the other parts, so that the edge of the end of the face may drop and the end face may be rounded. When the end face droop occurs, information cannot be recorded in that portion, which causes a reduction in recording capacity per one face of the substrate. Therefore, at the time of polishing, it is an important issue to reduce the end face droop on the polished surface of the magnetic disk substrate as much as possible.

  On the other hand, mechanical conditions such as making the polishing pad hard and reducing the polishing load have been studied, but sufficient effects have not been obtained.

  Further, various additives have been studied for reducing the end face droop. For example, addition of nonionic surfactants (Patent Documents 1 and 2), addition of polymer surfactants (Patent Document 3), addition of cellulose derivatives (Patent Document 4), alkylbenzene sulfonic acid surfactants and polyoxyethylene Addition of sulfate surfactants (Patent Documents 5 and 6) is considered.

JP 2002-167575 A Japanese Patent Laid-Open No. 2003-160781 JP 2003-342556 A Special table 2003-510446 gazette JP 2007-63372 A JP 2007-130728 A

  However, although the dripping of the end face is observed with these additives, the effect is not sufficient, and there is also a drawback that the polishing rate is extremely lowered.

  An object of the present invention is to reduce the end face droop (roll-off) of a substrate after polishing, and to prevent an extreme decrease in the polishing rate as compared with an abrasive composition having a good end face shape. Another object of the present invention is to provide an abrasive composition for rough polishing. Also provided are a magnetic disk substrate polishing method, a production method, and a magnetic disk substrate using a rough polishing abrasive composition.

  In order to solve the above problems, according to the present invention, the following abrasive composition for rough polishing, a method for polishing a magnetic disk substrate, a production method, and a magnetic disk substrate are provided.

[1] An abrasive, one or more of an acid and / or an acid salt, an oxidizing agent, a roll-off reducing agent that reduces roll-off, and water, wherein the roll-off reducing agent is a sulfonic acid-based anion An abrasive composition for rough polishing of an aluminum magnetic disk substrate plated with Ni-P , which is an ionic surfactant and / or sulfate anionic surfactant, and the anionic surfactant has an amide structure.

[2] The abrasive composition for rough polishing of an Ni-P plated aluminum magnetic disk substrate according to [1], wherein the roll-off reducing agent is an anionic surfactant represented by the structural formula ( I ).

（式中、Ｒ^１は炭素数が８〜１８のアルキル基、アルケニル基を示し、Ｒ^２は水素原子、メチル基又はエチル基を示し、Ｒ^３は炭素数が１〜８のアルキレン基、−（ＣＨ_２ＣＨ_２Ｏ）_ｍ−及び−（ＣＨ_２ＣＨ（ＣＨ_３）Ｏ）_ｎ−から選ばれる少なくとも一種からなる繰返し単位を示し、Ｍは水素、アルカリ金属、アルカリ土類金属、アンモニウム又は有機カチオンを示す。ここで、ｍ及びｎの合計は１〜８の整数である。）

(Wherein R ¹ represents an alkyl group or alkenyl group having 8 to 18 carbon atoms, R ² represents a hydrogen atom, a methyl group or an ethyl group, R ³ represents an alkylene group having 1 to 8 carbon atoms,- (CH ₂ CH ₂ O) _m — and — (CH ₂ CH (CH ₃ ) O) _n — represents a repeating unit consisting of at least one selected from the group consisting of hydrogen, alkali metal, alkaline earth metal, ammonium or organic. Represents a cation, where the sum of m and n is an integer from 1 to 8.)

[3] The abrasive composition for rough polishing of an Ni-P plated aluminum magnetic disk substrate according to [1] or [2], wherein an average particle size of the abrasive is larger than 0.03 μm and smaller than 5 μm.

[4] the [1] to [3] Aluminum, which is Ni-P plating polishing a magnetic disk substrate with a Ni-P plated aluminum disk substrate rough polishing abrasive composition according to any one of A method for polishing a magnetic disk substrate.

[ 5 ] A method for producing a Ni-P plated aluminum magnetic disk substrate using the method for polishing a magnetic disk substrate according to [ 4 ].

[ 6 ] A Ni-P plated aluminum magnetic disk substrate polished with the abrasive composition for rough polishing according to any one of [1] to [ 3 ].

  The abrasive composition for rough polishing of the present invention can polish the end face shape in a good state. In addition, while the existing roll-off reducing agent shows an extreme rate decrease, the rough polishing abrasive composition of the present invention polishes the end face shape in a good state while suppressing the decrease in the polishing rate. Can do.

It is sectional drawing of a board | substrate for demonstrating the measurement of Roll-off at the time of grind | polishing the surface of a board | substrate.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to the following embodiments, and changes, modifications, and improvements can be added without departing from the scope of the invention.

1. Abrasive composition for rough polishing:
The rough polishing abrasive composition of the present invention contains an abrasive, at least one acid and / or acid salt, an oxidizing agent, a roll-off reducing agent that reduces roll-off, and water. When an “acid” and an “acid salt” are included, the acids of the “acid” and “acid salt” may be the same acid or different acids. That is, the rough polishing abrasive composition may contain an acid and a salt of the acid or a salt of a different acid. The roll-off reducing agent is a sulfonic acid anionic surfactant and / or a sulfate ester anionic surfactant, and these anionic surfactants have an amide structure.

  Examples of the roll-off reducing agent include an anionic surfactant represented by the structural formula (I).

（式中、Ｒ^１は炭素数が８〜１８のアルキル基、アルケニル基を示し、Ｒ^２は水素原子、メチル基又はエチル基を示し、Ｒ^３は炭素数が１〜８のアルキレン基、−（ＣＨ_２ＣＨ_２Ｏ）_ｍ−及び−（ＣＨ_２ＣＨ（ＣＨ_３）Ｏ）_ｎ−から選ばれる少なくとも一種からなる繰返し単位を示し、Ｍは水素、アルカリ金属、アルカリ土類金属（Ｂｅ、Ｍｇ、Ｃａ、Ｓｒ、Ｂａ、Ｒａ）、アンモニウム又は有機カチオンを示す。ここで、ｍ及びｎの合計は１〜８の整数である。）

(Wherein R ¹ represents an alkyl group or alkenyl group having 8 to 18 carbon atoms, R ² represents a hydrogen atom, a methyl group or an ethyl group, R ³ represents an alkylene group having 1 to 8 carbon atoms,- (CH ₂ CH ₂ O) _m — and — (CH ₂ CH (CH ₃ ) O) _n — represents a repeating unit consisting of at least one selected from the group consisting of hydrogen, alkali metal, alkaline earth metal (Be, Mg). , Ca, Sr, Ba, Ra), ammonium or an organic cation, where the sum of m and n is an integer from 1 to 8.

As the surfactant in which R ³ is composed of at least one repeating unit selected from — (CH ₂ CH ₂ O) _m — and — (CH ₂ CH (CH ₃ ) O) _n —, amide ether sulfate Type anionic surfactants. Furthermore, among the amide ether sulfate type anionic surfactants, polyoxyalkylene fatty acid alkanol amide sulfate and salts thereof may be mentioned as surfactants in which the sum of m and n is 2 or more.

  Specific examples of these surfactants include polyoxyethylene coconut oil fatty acid monoethanolamide sulfate, polyoxyethyleneoxypropylene coconut oil fatty acid monoethanolamide sulfate, polyoxypropylene coconut oil fatty acid monoethanolamide sulfate, Examples thereof include oxyethylene myristic acid monoethanolamide sulfate and polyoxyethylene lauric acid monoethanolamide sulfate.

Examples of the surfactant in which R ³ is an alkylene group include N-acyl sulfonic acid type anionic surfactants. Furthermore, among the N-acyl sulfonic acid type anionic surfactants, N-acyl-N-alkyl taurates and N-acyl taurates are mentioned as surfactants whose alkylene group is an ethylene group.

  Specific examples of these surfactants include coconut oil fatty acid methyl taurate, lauroyl methyl taurate, myristoyl methyl taurate, palmitoyl methyl taurate, stearoyl methyl taurate, oleoyl methyl taurate, Examples include tallow fatty acid methyl taurate, palm oil fatty acid taurate, lauroyl taurate, myristoyl taurate, palmitoyl taurate, stearoyl taurate, oleoyl taurate, and beef tallow fatty acid taurate.

  The content of the roll-off reducing agent contained in the abrasive composition for rough polishing is preferably 0.001 to 5% by mass, more preferably 0.002 to 2% by mass, Most preferably, it is -1 mass%. When the content is small, a sufficient roll-off reduction effect cannot be obtained, and when the content is large, the rate is remarkably lowered, so that the content is preferably within the above range.

  As the abrasive, silicon oxide particles, aluminum oxide particles, titanium oxide particles, zirconium oxide particles, cerium oxide particles and the like can be used singly or in combination. In particular, it is preferable to use silicon oxide particles and aluminum oxide particles.

  Silicon oxide particles can be broadly classified into crystalline ones and amorphous ones. Examples of the crystalline silicon oxide particles include quartz, scale quartz, cristobalite, coatite, keatite, and stationite. Examples of amorphous silicon oxide particles include Rusaturjeite, opal, diatomaceous earth, and synthetic silica. Among these, amorphous synthetic silicon oxide particles are roughly classified into dry process silica, wet process silica, fused solid silica, colloidal silica, and the like. The dry process silica further includes flame hydrolysis process silica, arc process silica, plasma process silica and the like, depending on the production method. The wet method silica further includes precipitation method silica, gel method silica and the like depending on the production method. Examples of the fused solid silica include quartz glass. The colloidal silica may further be decationized colloidal silica, sol-gel colloidal silica, etc., depending on the production method. Colloidal silica has a general spherical shape, and can be chained, beaded, oval, confetti (small spheres with irregular protrusions (squares) on the surface) by adjusting the production method, etc. A shape other than the spherical shape is known. One or a combination of two or more of these silicon oxide particles can be used. Here, in the present specification, particles containing silicon oxide are referred to as silicon oxide particles. Further, silicon oxide particles are distinguished from colloidal silica and silicon oxide particles excluding colloidal silica, and silicon oxide particles excluding colloidal silica are referred to as silica particles.

  Aluminum oxide particles include α-type, γ-type, δ-type, η-type, θ-type, κ-type, and χ-type as crystal types, and crystal types other than α-type are collectively referred to as intermediate alumina. One or a combination of two or more of these crystal forms can be used.

  The average particle size of the abrasive contained in the abrasive composition for rough polishing is preferably larger than 0.03 μm and smaller than 5 μm, more preferably larger than 0.03 μm and smaller than 3 μm, and further larger than 0.03 μm. It is more preferably smaller than 1 μm, most preferably larger than 0.04 μm and smaller than 0.6 μm. When the average particle diameter is small, a sufficient polishing rate cannot be obtained, and when the average particle diameter is large, surface roughness, waviness, abrasive piercing, and the like occur, so the particle diameter is within the above range. It is preferable. In addition, when it uses in combination of 2 or more types as an abrasive | polishing material, the average particle diameter of the abrasive | polishing material contained in the abrasive | polishing agent composition for rough polishing is the average particle diameter of the whole after mixing.

  In this specification, the average particle diameter of colloidal silica means the particle diameter measured by the Sears method. As described in Analytical Chemistry Vol. 28, No. 12 (December 1956), p. 1981, the Sears method is a particle converted from a specific surface area by titration with sodium hydroxide. This is a diameter measurement method.

  Measurement of the average particle diameter of abrasive particles other than colloidal silica, such as silica particles and aluminum oxide particles, is obtained by measuring with a particle size distribution measuring device using a laser light diffraction method or a dynamic light scattering method. be able to. Here, the average particle diameter is arithmetically calculated from the particle size distribution obtained as a measurement result under the names of “average particle diameter”, “average value”, “average diameter”, etc., which are arithmetically calculated from the particle size distribution with a particle size distribution measuring device. Value.

  As the acid, one or more inorganic acids and / or organic acids can be used. As the inorganic acid, nitric acid, nitrous acid, sulfuric acid, phosphoric acid, hydrochloric acid, polyphosphoric acid, molybdic acid, perchloric acid, persulfuric acid, sulfurous acid, and the like can be used, but the use is not limited thereto. As the organic acid, carboxylic acid, organic phosphonic acid, and the like can be used. Specific examples include glycolic acid, oxalic acid, malonic acid, lactic acid, malic acid, tartaric acid, citric acid, isocitric acid, allocic acid, β- Hydroxypropionic acid, gluconic acid, glyoxylic acid, glyceric acid, mandelic acid, benzylic acid, salicylic acid, formic acid, acetic acid, propionic acid, butyric acid, hexanoic acid, heptanoic acid, octanoic acid, 2-ethylhexanoic acid, nonanoic acid, decane Acid, lauric acid, isobutyric acid, 1-hydroxyethylidene-1,1-diphosphonic acid, aminotrismethylenephosphonic acid, phosphonobutanetricarboxylic acid, ethylenediaminetetramethylenephosphonic acid, sulfamic acid, alkylbenzenesulfonic acid, naphthalenesulfonic acid, etc. It is preferable to use It is not limited to the use of al.

  Examples of the acid salt include the above-described acid metal salts, ammonium salts, organic amine salts, quaternary ammonium salts, and the like, but are not limited to these uses. Examples of the metal salt include metals belonging to Groups 1, 2, 3, 4, 6, 7, 8, 9, 10, 11, 12, and 13 of the periodic table. Examples of organic amines include dimethylamine, trimethylamine, alkanolamine and the like. Examples of quaternary ammonium include tetramethylammonium, tetraethylammonium, tetrabutylammonium and the like. Among these, ammonium salts and sodium salts and potassium salts which are salts of metals belonging to Group 1 are preferable, and ammonium salts are particularly preferable from the viewpoint of reducing end face sagging, but are not limited to these uses. Alternatively, an acid and a basic substance may be mixed to produce a salt in the system of the abrasive composition. Although it is possible to use only an acid or an acid salt alone, it is more preferable to include both an acid and an acid salt from the viewpoint of reducing end face drooping.

  Examples of the oxidizing agent include peroxide, permanganic acid or a salt thereof, chromic acid or a salt thereof, peroxo acid or a salt thereof, halogen oxo acid or a salt thereof, oxygen acid or a salt thereof, metal salt, sulfuric acid, oxidation thereof. Although what mixed 2 or more types of agents can be used, it is not limited to these use. Specifically, hydrogen peroxide, sodium peroxide, barium peroxide, potassium permanganate, chromic acid metal salt, dichromic acid metal salt, peroxodisulfate, ammonium peroxodisulfate, peroxodisulfate metal salt, peroxo Phosphoric acid, peroxosulfuric acid, sodium peroxoborate, performic acid, peracetic acid, perbenzoic acid, perphthalic acid, hypochlorous acid, hypobromous acid, chloric acid, bromic acid, iodic acid, sodium hypochlorite, Calcium hypochlorite, iron chloride (III), iron sulfate (III), iron citrate (III), ammonium iron sulfate (III), and the like can be used. In particular, among peroxides and peroxo acids, use of hydrogen peroxide, peroxodisulfuric acid and its salt, hypochlorous acid and its salt, etc. is preferable, but it is not limited to these uses.

  Furthermore, the abrasive composition for rough polishing of the present invention has an effect of promoting polishing, an effect of reducing surface roughness, an effect of reducing waviness and nodules, an effect of improving redispersibility of an abrasive composition for rough polishing and an effect of suppressing aggregation. Other additives shown may be included, and these additives include thickeners, dispersants, rust inhibitors, basic substances, surfactants, alumina sol (alumina hydrate and aluminum hydroxide selected Or the like in which at least one kind dispersed in a colloidal form is used. Moreover, in the abrasive | polishing agent used for grinding | polishing of a general semiconductor etc., an anticorrosive agent may be contained, but anticorrosive agent becomes a factor which causes a fall of a polishing rate in the abrasive | polishing agent composition for rough polishing of this invention. In some cases, it is preferable not to include an anticorrosive.

2. Use of abrasive composition for rough polishing:
The abrasive composition for rough polishing of the present invention is suitable for use in polishing a magnetic disk substrate such as an Ni-P plated aluminum magnetic disk substrate (hereinafter “aluminum disk”) or a glass magnetic disk substrate. It is particularly suitable for use in polishing aluminum disks. Accordingly, the present invention is a magnetic disk substrate polishing method for polishing a magnetic disk substrate using the above-described rough polishing abrasive composition, and a magnetic disk substrate manufacturing method using the polishing method. Further, the abrasive composition for rough polishing of the present invention comprises a semiconductor substrate such as silicon carbide, silicon, germanium, gallium arsenide, gallium phosphide, indium phosphide, gallium nitride, or a single material such as sapphire, lithium tantalate, or lithium niobate. It can also be used for polishing crystal substrates and magnetic heads.

  As a polishing method to which the rough polishing abrasive composition of the present invention can be applied, for example, a polishing pad is affixed to a surface plate of a polishing machine, and the surface or polishing pad of an object (for example, an aluminum disk) is polished. There is a method of supplying a rough polishing abrasive composition to the surface and rubbing the surface to be polished with a polishing pad (referred to as polishing). For example, when simultaneously polishing the front surface and the back surface of an aluminum disk used for a magnetic disk substrate, there is a method using a double-side polishing machine in which a polishing pad is attached to each of an upper surface plate and a lower surface plate. In this method, an aluminum disk is sandwiched between polishing pads attached to an upper surface plate and a lower surface plate, a polishing composition for rough polishing is supplied between the polishing surface and the polishing pad, and the two polishing pads are rotated simultaneously. Then cut the front and back of the aluminum disc.

  As the polishing pad, a urethane type, a suede type, a non-woven fabric type, or any other type can be used.

  In polishing, a process called rough polishing is generally performed in which a surface of an object is roughly roughened using an abrasive composition containing an abrasive having a large average particle size, and then rough polishing is performed. For the surface, a process called finish polishing is performed in which a polishing composition containing an abrasive having a small average particle diameter is used to gradually scrape the surface. In addition, the rough polishing process may be performed in a plurality of polishing processes. For example, after performing a polishing process to adjust the shape of the entire substrate such as edge sag and undulation, another abrasive composition is flowed to the same polishing machine polishing pad to deteriorate the shape of the entire substrate such as edge swell and swell. In some cases, a polishing process such as removing residuals such as abrasive grains may be performed. In the rough polishing process, the main focus is on adjusting the shape of the entire substrate, such as edge sag and waviness. On the other hand, in the final polishing process, the main focus is on adjusting the surface accuracy of the substrate surface such as surface roughness and scratches. For these reasons, it is preferable to apply the abrasive composition for rough polishing of the present invention showing the effect of reducing the end face dripping to any step included in the rough polishing.

  In addition, the pad used is different in the rough polishing process and the final polishing process due to the above-described difference in purpose. For example, in the polishing of a magnetic disk substrate, a suede pad is mainly used, but the polishing pad used in the rough polishing process tends to have a larger hole diameter than the polishing pad used in the final polishing process. . In order for the abrasive composition for rough polishing of the present invention to sufficiently exhibit the effect of reducing the end face droop, it is preferable to use a polishing pad used in the rough polishing step.

  The method for producing a magnetic disk substrate of the present invention includes a polishing step using the coarse polishing abrasive composition. Here, the polishing step is not particularly limited as long as the polishing method is used, but the polishing composition for rough polishing is preferably used in any step included in the rough polishing.

  The reason why the polishing composition for rough polishing according to the present invention can reduce the end face sagging is as follows, although the mechanism is not clear. By adding the surfactant of the present invention, the viscosity and surface tension of the abrasive composition for rough polishing, and the dispersed state of the abrasive particles in the abrasive composition for rough polishing become suitable. During this period, the abrasive smoothly enters, and the retention of the abrasive near the end face of the substrate is suppressed. As a result, it is considered that the end face is prevented from being excessively shaved, leading to reduction of the end face dripping.

  EXAMPLES Hereinafter, although this invention is demonstrated further in detail based on an Example, this invention is not limited to these Examples.

(1) Preparation method of rough polishing abrasive composition (Examples 1-14, Comparative Examples 1-12)
A rough polishing abrasive composition containing ion-exchanged water and the following materials in the proportions shown in Tables 1 to 3 (the total of the ion-exchanged water and the following materials was 100% by mass) was prepared.

Colloidal silica particles I (average particle size: 44 nm, commercially available colloidal silica. Content is shown in the table)
Colloidal silica particles II (average particle size: 55 nm, commercially available colloidal silica. The content is shown in the table. However, Example 10 and Comparative Example 11 are not included.)
Silica particles (average particle size: 0.3 μm, commercially available precipitated silica was adjusted to the above particle size. The content is shown in the table. However, Example 10 and Comparative Example 11 are not included.)
Sulfuric acid (content is shown in the table)
Ammonium sulfate (content is shown in the table. However, Example 11 and Comparative Example 12 are not included.)
Hydrogen peroxide 1.24% by mass
Roll-off reducing agent (the following surfactants A to F, the contents are shown in the table. However, Comparative Examples 1, 11 and 12 are not included)

A: Polyoxyethylene coconut oil fatty acid monoethanolamide sulfate sodium salt (NOF Sanamide C-3)

（Ｒ^１はヤシ油由来）

^{(R 1} is derived from coconut oil)

B: Fatty acid amide ether sulfate sodium salt (NOF Sanamide CF-3)

C: Palm oil fatty acid methyl taurate sodium salt (Nippon Diapon K-SF)

（Ｒ^１はヤシ油由来）

^{(R 1} is derived from coconut oil)

D: Sodium lauryl sulfate (manufactured by Toho Chemical, ALSCO LS-30)

E: Sodium polyoxyethylene tridecyl ether sulfate (Daiichi Kogyo Seiyaku Hightenol 330T)

F: Polyoxyethylene alkylsulfosuccinate disodium (Kohaku L-400A manufactured by Toho Chemical)

  The average particle size of the colloidal silica particles used was measured by the Sears method. Hereinafter, the particle diameter measuring method by the Sears method will be described.

(1) The amount of colloidal silica dispersion containing 1.5 g of colloidal silica was calculated by the following equation.
Sample amount Wr (g) = 150 / Colloidal silica concentration (%) in the colloidal silica dispersion
(2) The amount of colloidal silica dispersion calculated in (1) was weighed into a beaker. The actual weighing value was defined as Wa (g).
(3) 100 ml of pure water was added to the weighed colloidal silica dispersion.
(4) A 0.1 mol / l hydrochloric acid aqueous solution was further added so that the pH was 3 to 3.5.
(5) 30 g of sodium chloride was added, and 50 ml of pure water was added and stirred.
(6) A 0.1 mol / l sodium hydroxide aqueous solution was titrated until the pH reached 4.0 while the pH electrode was immersed in the solution and stirred.
(7) Subsequently, a 0.1 mol / l aqueous sodium hydroxide solution was titrated until the pH reached 9.0. Here, the amount of 0.1 mol / l aqueous sodium hydroxide solution required for titration from pH 4.0 to 9.0 was defined as Vs (ml).
(8) Blank measurement was performed. 150 ml of pure water was added to 30 g of sodium chloride and stirred, and 0.1 mol / l hydrochloric acid aqueous solution was added so that the pH was 3 to 3.5. Further, titration was performed in the same manner as in (6) and (7), and the amount of 0.1 mol / l sodium hydroxide aqueous solution required for titration to pH 4.0 to 9.0 was defined as Vb (ml). .
(9) The specific surface area SSA was calculated.
Specific surface area SSA (m ² /g)=26.5 (Vs−Vb) / (Wr / Wa)
(10) The average particle diameter D was calculated from the specific surface area.
Average particle diameter D (nm) = 3100 / SSA
(The colloidal silica density was calculated as 1.9 g / cm ^3. )

  The average particle diameter of the silica particles is measured using a dynamic light scattering particle size distribution measuring device (Microtrac UPA, manufactured by Nikkiso), and the particle size distribution is based on volume. Moreover, the average particle diameter of the silicon oxide particle abrasive | polishing material of Examples 1-9, 11-14, Comparative Examples 1-10, and Comparative Example 12 which mixed the colloidal silica particle I, the colloidal silica particle II, and the silica particle is dynamic. It was 0.1 μm when measured using a light scattering particle size distribution analyzer (Microtrac UPA, manufactured by Nikkiso). The particle size distribution is based on volume.

(Examples 15 to 17, Comparative Example 13)
A rough polishing abrasive composition containing ion-exchanged water and the following materials in the proportions shown in Table 4 (the total of the ion-exchanged water and the following materials was 100% by mass) was prepared.

α-Alumina (average particle size: 0.4 μm, commercially available α-alumina was pulverized and wet-classified to adjust the particle size. The content is shown in the table.)
Intermediate alumina (average particle size: 0.4 μm, commercially available aluminum hydroxide was calcined, pulverized and wet classified to adjust the particle size. The content is shown in the table.)
Sulfuric acid 0.96% by mass
Ammonium sulfate 1.20% by mass
Hydrogen peroxide 1.24% by mass
Roll-off reducing agent (Surfactant A, content is shown in the table. However, Comparative Example 13 is not included)

  The average particle diameters of α-alumina and intermediate alumina are measured using a laser diffraction particle size distribution analyzer (SALD2200, manufactured by Shimadzu Corporation), and the particle size distribution is based on volume. Moreover, the average particle diameter of the aluminum oxide particle abrasive | polishing material of Examples 15-17 and the comparative example 13 which mixed (alpha) -alumina and intermediate | middle alumina was measured using the laser diffraction type particle size distribution measuring machine (SALD2200, Shimadzu Corporation make). However, it was 0.4 μm. The particle size distribution is based on volume.

(2) Polishing conditions Polishing was performed under the following polishing conditions using an Ni-P electroless plated aluminum disk with an outer diameter of 2.5 inches as a substrate to be polished.
Polishing machine: 9B double-side polishing machine made by Speed Fem Co., Ltd. Polishing pad: PIL pad surface plate made by FILWEL Co., Ltd .: Upper platen-7.5 rpm
Lower surface plate 22.5rpm
Abrasive supply amount: 100 ml / min Polishing time: Polishing is performed for a time during which the polishing amount is 1.2 to 1.5 μm / single side (130 to 1500 seconds).
Processing pressure: 9.8 kPa

(3) Evaluation of Polished Disk Surface (3-1) Polishing Rate Ratio The polishing rate was calculated based on the following formula by measuring the mass of the aluminum disk that decreased after polishing.
Polishing rate (μm / min) = Amount of mass reduction of aluminum disk (g) / Polishing time (min) / Aluminum disk one side area (cm ² ) / Ni-P plating density (g / cm ³ ) × 10 ⁴
(However, in the above formula, the area of one side of the aluminum disk is 28.3 cm ² and the density of the Ni-P plating is 8.0 g / cm ³ )

  The polishing rate ratio is a relative value when the polishing rate of Comparative Example 1 obtained by using the above formula is set to 1 in Examples 1 to 9 and Comparative Examples 2 to 10. In Example 10, it is a relative value when the polishing rate of Comparative Example 11 obtained using the above formula is 1. In Examples 11-14, it is a relative value when the polishing rate of Comparative Example 12 obtained using the above formula is 1. In Examples 15-17, it is a relative value when the polishing rate of Comparative Example 13 obtained using the above formula is 1.

(3-2) Roll-off ratio As an evaluation of the end face shape, roll-off was measured by quantifying the degree of end face droop. Roll-off was measured using a measuring apparatus [New View 5010 (lens: 2.5 times, zoom: 0.5 times)] manufactured by Zygo and analysis software (Metro Pro) manufactured by Zygo.

  The roll-off measurement method will be described with reference to FIG. FIG. 1 is a cross-sectional view of a 2.5-inch aluminum disk plated with electroless Ni-P, which is an object to be polished, perpendicular to the polished surface passing through the center of the disk. In measurement of Roll-off, first, a perpendicular h is provided along the outer peripheral edge of the disk, and the distance from the perpendicular h is parallel to the perpendicular h toward the center of the disk on the polished surface from the perpendicular h. A line j having a length of 50 mm was provided, and a position where the line of the cross section of the disk intersected with the line j was defined as a point A. Further, a line k parallel to the perpendicular h and having a distance of 0.50 mm from the perpendicular h is provided, and a position where a line of the cross section of the disk intersects with the line k is defined as a point B. A line m connecting point A and point B is provided, a line t perpendicular to the line m is provided, a position where the cross section line of the disk intersects the line t is a point C, and a position where the line m intersects the line t is a point D. It was. Then, the distance at which the distance between the points C and D was maximized was measured as Roll-off.

  The Roll-off ratio is a relative value in Examples 1 to 9 and Comparative Examples 2 to 10, where the Roll-off of Comparative Example 1 obtained using the above formula is 1. In Example 10, it is a relative value when Roll-off of Comparative Example 11 obtained using the above formula is 1. In Examples 11-14, it is a relative value when Roll-off of Comparative Example 12 obtained using the above formula is 1. In Examples 15-17, it is a relative value when Roll-off of the comparative example 13 calculated | required using the said Formula is set to 1. Therefore, if the value is smaller than 1, it can be said that the end face is improved.

(3-3) Results When silicon oxide particles are used for the abrasive, Comparative Examples 1, 11 and 12 that do not contain a roll-off reducing agent and Examples 1 to 9, 10 and 11 to 14 are compared. When the roll-off reducing agent of the invention is used, Roll-off is small, and it can be seen that the end face droop is reduced. Moreover, when Comparative Examples 2-10 containing the roll-off reducing agent known until now and Examples 1-9 are compared, even if it is the same content, when the roll-off reducing agent of this invention is used, It can be seen that the Roll-off is smaller, and the end face droop is reduced. When the ammonium salt is contained from Examples 11 to 14, the end face droop can be further reduced. In addition, with the roll-off reducing agent that has been known so far, the polishing rate is drastically reduced depending on the content. However, when the roll-off reducing agent of the present invention is used, the reduction of the polishing rate can be suppressed. You can see that

  When aluminum oxide particles are used for the abrasive, Comparative Example 13 not containing a roll-off reducing agent and Examples 15 to 17 are compared. When the roll-off reducing agent of the present invention is used, Roll-off is small. It can be seen that the end face sagging is reduced.

  The rough polishing abrasive composition of the present invention can be used for polishing magnetic disk substrates, magnetic heads, semiconductor substrates, single crystal substrates and the like. Among these, it is particularly suitable for use in polishing a magnetic disk substrate, and can finish a polished surface at a higher rate than an abrasive having a good end face shape and a good end face shape.

Claims (6)

An abrasive, at least one acid and / or acid salt, an oxidizing agent, a roll-off reducing agent that reduces roll-off, and water;
The roll-off reducing agent is a sulfonic acid anionic surfactant and / or a sulfate ester anionic surfactant, and these anionic surfactants have an amide structure and are plated with Ni-P. An abrasive composition for rough polishing of a disk substrate. The abrasive composition for rough polishing of an Ni-P plated aluminum magnetic disk substrate according to claim 1, wherein the roll-off reducing agent is an anionic surfactant represented by the structural formula ( I ).

(Wherein R ¹ represents an alkyl group or alkenyl group having 8 to 18 carbon atoms, R ² represents a hydrogen atom, a methyl group or an ethyl group, R ³ represents an alkylene group having 1 to 8 carbon atoms,- (CH ₂ CH ₂ O) _m — and — (CH ₂ CH (CH ₃ ) O) _n — represents a repeating unit consisting of at least one selected from the group consisting of hydrogen, alkali metal, alkaline earth metal, ammonium or organic. Represents a cation, where the sum of m and n is an integer from 1 to 8.)   The abrasive composition for rough polishing of an Ni-P plated aluminum magnetic disk substrate according to claim 1 or 2, wherein the abrasive has an average particle size of more than 0.03 µm and less than 5 µm.   A Ni-P plated aluminum magnetic disk substrate, wherein the Ni-P plated aluminum magnetic disk substrate rough polishing abrasive composition according to any one of claims 1 to 3 is used to polish the magnetic disk substrate. Polishing method.   A method for manufacturing a Ni-P plated aluminum magnetic disk substrate using the magnetic disk substrate polishing method according to claim 4.   An aluminum magnetic disk substrate plated with Ni-P and polished using the abrasive composition for rough polishing according to claim 1.

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