TW202018053A - Polishing composition for magnetic disk substrate - Google Patents

Abstract

To reduce rolling and roll-off of a substrate after polishing while maintaining a polishing rate. A polishing agent composition is an aqueous composition containing at least alumina particles, a water-soluble polymer compound, and an organic sulfuric acid ester compound. Here, the water-soluble polymer compound is a mixture including a polymer containing a monomer having a carboxylic acid group as an essential monomer and a polymer containing a monomer having a sulfonic acid group as an essential monomer, and/or a copolymer containing a monomer having a carboxylic acid group and a monomer having a sulfonic acid group as an essential monomer.

Description

Abrasive composition for magnetic disk substrate

The present invention relates to an abrasive composition for polishing electronic components such as so-called magnetic recording media such as semiconductors and hard disks. In particular, it relates to an abrasive composition for polishing the surface of a substrate for a magnetic recording medium such as a glass disk substrate or an aluminum disk substrate. In addition, it relates to an abrasive composition for polishing the surface of an aluminum disk substrate for a magnetic recording medium in which an electroless nickel-phosphorus plating film is formed on the surface of an aluminum alloy substrate.

Traditionally, from the viewpoint of production efficiency, as an abrasive composition for polishing the surface of electroless nickel-phosphorus electroplated coatings on aluminum disk substrates, aluminum oxide particles which can achieve a higher polishing rate with water have been used Dispersed abrasive composition.

For the purpose of increasing the polishing speed, reducing dents and reducing roll-off, it is proposed to use alumina particles of various crystal structures in the abrasive composition using alumina-based abrasive particles to increase the polishing speed and reduce dents and roll-off Phenomenon and other high-quality polished surfaces coexist.

Patent Document 1 proposes that by using an abrasive composition containing alumina abrasive grains of a predetermined size of γ, δ, and θ type, the polishing speed is increased, and a higher quality polishing surface can be obtained than in the past.

Patent Document 2 proposes that by using an abrasive composition containing alumina other than α-alumina, that is, intermediate alumina, the degree of surface recession can be reduced and the polishing rate can be increased case.

Patent Document 3 proposes that by using an abrasive composition containing α-alumina and intermediate alumina, it is possible to achieve a high polishing rate and reduce dents. However, the dent reduction effect is not sufficient, and improvement is being sought.

Patent Document 4 proposes that when an abrasive material composition containing abrasives, grinding aids and water is used to polish a magnetic recording medium substrate, an aliphatic organic sulfate can be used as a grinding aid to increase the grinding speed and Plan to reduce surface roughness. However, this solution is not sufficient for increasing the polishing speed and reducing the surface roughness, and is seeking improvement.

[Prior Technical Literature]

Patent Literature

Patent Document 1: Japanese Patent Laid-Open No. 11-268911

Patent Document 2: Japanese Patent Laid-Open No. 2001-89746

Patent Document 3: Japanese Patent Laid-Open No. 2005-23266

Patent Literature 4: International Publication No. 1998/021289

However, as described in Patent Documents 1 to 4, if an abrasive composition added with intermediate alumina is used to polish a magnetic disk substrate, it will cause problems such as deterioration of the dent after polishing and product quality degradation.

The problem of the present invention is to maintain the polishing speed, and to achieve the reduction of the degree of depression of the substrate after the polishing and the reduction of the roll-off phenomenon.

In view of the above-mentioned problems, the present inventors diligently studied the addition of various etchants, found that the above-mentioned problems can be solved, and completed the present invention. That is, the present invention is the following abrasive composition.

[1] An abrasive composition for a magnetic disk substrate containing alumina particles, a water-soluble high molecular weight compound, an organic sulfate ester compound, and water. Wherein the water-soluble high molecular weight compound is a mixture of a polymer containing a monomer having a carboxylic acid group as an essential monomer and a polymer using a monomer having a sulfonic acid group as an essential monomer, and/or The carboxylic acid group monomer and the sulfonic acid group monomer are copolymers of essential monomers; and the organic sulfate ester salt compound is represented by the following general formula (1) RO-SO ₃ M (1) In the formula, R It represents a linear or branched alkyl group, alkenyl group, allyl group or allyl group with a carbon number of 5 to 21. M represents an alkali metal, alkaline earth metal, ammonium ion or organic cation.

[2] An abrasive composition for a magnetic disk substrate containing alumina particles, a water-soluble high molecular weight compound, an organic sulfate ester compound, and water. Wherein the water-soluble high molecular weight compound is a mixture of a polymer containing a monomer having a carboxylic acid group as an essential monomer and a polymer using a monomer having a sulfonic acid group as an essential monomer, and/or The carboxylic acid group monomer and the sulfonic acid group monomer are copolymers of essential monomers; and the organic sulfate ester salt compound is represented by the following general formula (2) RO-(AO) _n -SO ₃ M (2) In the formula, R represents a linear or branched alkyl group, alkenyl group, allyl group or allyl group having 5 to 21 carbon atoms, AO represents an oxyalkylene group having 2 or 3 carbon atoms, and n represents 1 to 1 Natural number of 30, M represents alkali metal, alkaline earth metal, ammonium ion or organic cation.

[3] The abrasive composition for a magnetic disk substrate as described in [1] or [2] above, in which the water-soluble high molecular weight compound is a monomer having a carboxylic acid group and a monomer having a sulfonic acid group A monomer copolymer is a copolymer in which a monomer having a carboxylic acid group, a monomer having a sulfonic acid group and a monomer having an amide group are essential monomers.

[4] The abrasive composition for a magnetic disk substrate as described in any one of [1] to [3] above, wherein the alumina particles contain α-alumina and the average particle diameter is 0.1 to 2.0 μm, and The concentration in the composition is 1-50% by mass.

[5] The abrasive composition for a magnetic disk substrate as described in any one of [1] to [4] above, wherein the single system having a carboxylic acid group is selected from acrylic acid or its salts, methacrylic acid or Monomers of its salts.

[6] The abrasive composition for a magnetic disk substrate as described in any one of [1] to [5] above, wherein the single system having a sulfonic acid group is selected from isoprenesulfonic acid and 2-propene Acetylamine-2-methylpropanesulfonic acid, 2-methacrylamide-2-methylpropanesulfonic acid, styrenesulfonic acid, ethylenesulfonic acid, propylenesulfonic acid, isopentenylsulfonic acid, ethylenenaphthalenesulfonic acid And one or more than two monomers of its salts.

[7] The abrasive composition for a magnetic disk substrate as described in [3] above, wherein the single system having an amide group is selected from acrylamide, methacrylamide, N-alkylacrylamide, N-alkyl methacrylamide monomer.

[8] The abrasive composition for a magnetic disk substrate as described in any one of [1] to [7] above, wherein the polymer having the carboxylic acid group-containing monomer as an essential monomer, the sulfonate The acid group-based monomer is a polymer of essential monomers, the copolymer having the carboxylic acid group-containing monomer and the sulfonic acid group-based monomer as essential monomers, and the carboxylic acid group-containing monomer and the sulfonate group The weight average molecular weight of the acid group-based monomer and the amide group-based monomer are essential monomers, each of which is 1,000 or more and 1,000,000. under.

[9] The abrasive composition for a magnetic disk substrate according to any one of the above [1] to [8], wherein the abrasive composition further contains an acid and/or its salt, and the pH value (25°C ) Ranges from 0.1 to 4.0.

[10] The abrasive composition for a magnetic disk substrate according to any one of [1] to [9] above, wherein the abrasive composition further contains an oxidizing agent.

[11] The abrasive composition for a magnetic disk substrate according to any one of the above [1] to [10], which is used to polish an electroless nickel-phosphorus plated aluminum magnetic disk substrate.

The polishing composition for a magnetic disk substrate of the present invention can maintain the polishing speed, and at the same time reduce the degree of depression on the surface of the substrate and reduce the roll-off phenomenon.

A, B, C, D ‧‧‧ points

h‧‧‧Vertical

j, k, m, t ‧‧‧ line

FIG. 1 is a diagram illustrating the measurement of the roll-off phenomenon when polishing the surface of a substrate.

The embodiments of the present invention are described below, but the present invention is not limited to the following embodiments. Those with ordinary knowledge in the technical field to which the present invention pertains may make appropriate changes and improvements to the following embodiments without departing from the scope of the invention. Etc., and still fall within the scope of the invention.

1. Abrasive composition

The abrasive composition of the present invention is an aqueous composition containing at least alumina particles, a water-soluble high molecular weight compound, and an organic sulfate salt compound. Here, the water-soluble polymer Is a mixture of a polymer containing a monomer having a carboxylic acid group as an essential monomer and a polymer having a monomer having a sulfonic acid group as an essential monomer, and/or a monomer having a carboxylic acid group And monomers with sulfonic acid groups are copolymers of essential monomers.

(1) Alumina particles

The colloidal silica contained in the abrasive composition for a magnetic disk substrate of the present invention preferably has an average particle diameter (D50) of 5 to 200 nm. By setting the average particle diameter (D50) to 5 nm or more, it is possible to suppress a decrease in the polishing rate. By setting the average particle diameter (D50) to 200 nm or less, the deterioration of surface smoothness can be suppressed. The average particle diameter (D50) of colloidal silica is more preferably 10 to 150 nm, and particularly preferably 20 to 120 nm.

As a raw material for preparing alumina, gibbsite: Al ₂ O ₃ ‧3H ₂ O, diaspore: Al ₂ O ₃ ‧H ₂ O, diaspore-like: Al ₂ O ₃ ‧nH ₂ O(n=1~2) etc. These alumina raw materials can be prepared as follows, for example.

Gibbsite: Al ₂ O ₃ ‧3H ₂ O

Dissolve the bauxite with a hot solution of sodium hydroxide, and then cool the solution obtained by filtering to remove insoluble components. Finally, the resulting precipitate is dried to obtain gibbsite.

Diaspore: Al ₂ O ₃ ‧H ₂ O

The aluminum alkoxide obtained after the reaction of metallic aluminum and ethanol: Al(OR) ₃ is hydrolyzed to obtain diaspore.

Diaspore-like: Al ₂ O ₃ ‧nH ₂ O(n=1~2)

The gibbsite is treated with water vapor under alkaline ambient gas, it can be like diaspore.

After firing these alumina raw materials, α-alumina, γ-alumina, δ-oxidation can be obtained Aluminum, θ-alumina, etc.

The average particle diameter (D50) of the alumina particles is preferably 0.1 to 2.0 μm, and particularly preferably 0.2 to 1.0 μm. By setting the average particle diameter of the alumina particles to 0.1 μm or more, it is possible to suppress a decrease in the polishing rate. By setting the average particle diameter of the alumina particles to 2.0 μm or less, it is possible to suppress the deterioration of the degree of depression after polishing.

The concentration of alumina particles in the entire abrasive composition is preferably 1 to 50% by mass, particularly preferably 2 to 40% by mass. By setting the concentration of the alumina particles to 1% by mass or more, the decrease in the polishing rate can be suppressed. By setting the concentration of alumina particles to 50% by mass or less, unnecessary alumina particles need not be used, and grinding can be performed more economically and advantageously.

(2) Water-soluble high molecular weight compounds

The water-soluble high molecular weight compound used in the present invention is a mixture of a polymer containing a monomer having a carboxylic acid group as an essential monomer and a polymer using a monomer having a sulfonic acid group as an essential monomer, and/or The monomer having a carboxylic acid group and the monomer having a sulfonic acid group are copolymers of essential monomers. In addition, monomers other than these can also be used. Examples of monomers other than monomers having a carboxylic acid group and monomers having a sulfonic acid group include monomers having an amide group.

(2-1) Monomer with carboxylic acid group

As the monomer having a carboxylic acid group, an unsaturated aliphatic amide and its salts are preferably used. More specifically, acrylic acid, methacrylic acid, maleic acid, itaconic acid, and salts of these can be mentioned. Examples of the salts include sodium salt, potassium salt, magnesium salt, ammonium salt, amine salt, and alkyl ammonium salt.

Among the water-soluble high-molecular-weight compounds, the pH value of the water-soluble high-molecular-weight compound can be evaluated according to the proportion of the monomer having a carboxylic acid group in the acid state or in the salt state. . If the ratio of acid is higher, the pH value becomes lower, If the proportion of salt is higher, the pH value becomes higher. In the present invention, for example, in an aqueous solution having a water-soluble high molecular weight compound concentration of 10% by mass, a water-soluble high molecular weight compound having a pH value (25° C.) in the range of 0.1 to 13 can be used.

(2-2) Monomer with sulfonic acid group

Specific examples of the monomer having a sulfonic acid group include isoprenesulfonic acid, 2-acrylamide-2-methylpropanesulfonic acid, 2-methacrylamide-2-methylpropanesulfonic acid , Styrenesulfonic acid, ethylenesulfonic acid, propylenesulfonic acid, isopentenylsulfonic acid, vinylnaphthalenesulfonic acid and their salts. One kind or two or more kinds can be selected and used as a monomer. Preferred examples include 2-acrylamide-2-methylpropanesulfonic acid, 2-methacrylamide-2-methylpropanesulfonic acid, and salts thereof.

(2-3) Other monomers

The water-soluble high-molecular-weight compound used in the present invention uses monomers having a carboxylic acid group and monomers having a sulfonic acid group as essential monomers, but monomers other than these can also be used. For example, a monomer having an amide group can also be used. Specifically, acrylamide, methacrylamide, N-alkylacrylamide, N-alkylmethacrylamide, and the like can be used.

Specific examples of N-alkylacrylamide and N-alkylmethacrylamide include N-methacrylamide, N-ethylacrylamide, Nn-propylacrylamide, and N- Isopropylacrylamide, Nn-butylacrylamide, N-isobutylacrylamide, N-secondary butylacrylamide, N-tert-butylacrylamide, N-methylmethacryl Acetamide, N-ethylmethacrylamide, Nn-propylmethacrylamide, N-isopropylmethacrylamide, Nn-butylmethacrylamide, N-isobutylmethacrylamide , N-secondary butyl methacrylamide, N-tert-butyl methacrylamide, etc.

(2-4) Mixture of polymers

The water-soluble high molecular weight compound used in the present invention may also be a mixture of a polymer containing a monomer having a carboxylic acid group as an essential monomer and a polymer containing a monomer having a sulfonic acid group as an essential monomer. In this case, as a polymer constituting the mixture, as a polymer having a monomer having a carboxylic acid group as an essential monomer, a polymer obtained by polymerizing a monomer having a carboxylic acid group, a polymer having a carboxylic acid group Copolymer of monomer and monomer with sulfonic acid group, copolymer of monomer with carboxylic acid group and other monomer, copolymerization of monomer with carboxylic acid group and monomer with sulfonic acid group and other monomer Things.

In addition, as a polymer in which a monomer having a sulfonic acid group is an essential monomer, a polymer obtained by polymerizing a monomer having a sulfonic acid group, a monomer having a carboxylic acid group, and a monomer having a sulfonic acid group Copolymers, copolymers of monomers with sulfonic acid groups and other monomers, copolymers of monomers with carboxylic acid groups and monomers with sulfonic acid groups and other monomers, etc.

Mixtures of polymers containing monomers with carboxylic acid groups as essential monomers and polymers with monomers with sulfonic acid groups as essential monomers are derived from these monomers with carboxylic acid groups as essential monomers Among polymers of polymers and polymers that use monomers with sulfonic acid groups as essential monomers, a mixture of more than one polymer. In the mixture, the proportion of the polymer having a monomer having a carboxylic acid group as an essential monomer is preferably 5 to 95% by mass, particularly preferably 8 to 92% by mass, and more preferably 10 to 90% by mass. In the mixture, the ratio of the polymer having a monomer having a sulfonic acid group as an essential monomer is preferably 5 to 95% by mass, particularly preferably 8 to 92% by mass, and more preferably 10 to 90% by mass.

(2-5) Copolymer

The water-soluble high molecular weight compound used in the present invention may also be a copolymer in which a monomer having a carboxylic acid group and a monomer having a sulfonic acid group are essential monomers. In the copolymer, the proportion of monomers having a carboxylic acid group as a constituent unit is preferably 5 to 95 mol%, particularly preferably 8 to 92 mol%, and more preferably 10 to 90 mol%. The proportion of monomers with sulfonic acid groups as constituent units, preferably 5 to 95 mol%, particularly preferred It is 8 to 92 mol%, more preferably 10 to 90 mol%.

(2-6) Preparation method of water-soluble high molecular weight compound

Although the preparation method of the water-soluble high molecular weight compound is not particularly limited, it is preferably an aqueous solution polymerization method. By the aqueous solution polymerization method, a uniform solution can be formed to obtain a water-soluble high molecular weight compound. The polymerization solvent in the above-mentioned aqueous solution polymerization is preferably an aqueous solvent, particularly preferably water. In addition, in order to improve the solubility of the above monomer components to the solvent, an organic solvent can be added appropriately within a range that does not adversely affect the polymerization of each monomer. Examples of the organic solvent include ethanols such as isopropyl ethanol and ketones such as acetone. These solvents can be used alone or in combination of two or more.

The following describes the preparation method of the water-soluble high molecular weight compound using the above-mentioned aqueous solvent. During the polymerization reaction, a well-known polymerization initiator can be used, and a radical polymerization initiator is particularly preferably used. Examples of radical polymerization initiators include: persulfates such as sodium persulfate, potassium persulfate or ammonium persulfate; hydroperoxides such as t-butyl hydroperoxide; water-soluble peroxides such as hydrogen peroxide, Ketone peroxides such as methyl ethyl ketone peroxide and cyclohexanone peroxide; dialkyl peroxides such as di-tert-butyl peroxide and tert-butyl cumene peroxide Soluble peroxides; azo compounds such as azobisisobutyronitrile, 2,2-azobis(2-methylpropionamidine) dihydrochloride. Only one kind of these peroxide-based radical polymerization initiators may be used, or two or more kinds may be selected for use in combination. Among the above-mentioned peroxide-based radical polymerization initiators, if it is easy to control the molecular weight of the water-soluble high molecular weight compound produced, it is preferably a persulfate or an azo compound, and particularly preferably an azobis Isobutyronitrile.

Although the amount of the above radical polymerization initiator is not particularly limited, if it is based on the total mass of all monomers of the water-soluble high molecular weight compound, it is preferably used at a ratio of 0.1 to 15% by mass, and particularly preferably 0.5 ~10% by mass. By raising the ratio to 0.1 Above mass%, the copolymerization rate can be improved, and controlling the ratio below 15 mass% can improve the stability of the water-soluble high molecular weight compound.

In addition, water-soluble high-molecular-weight compounds can be prepared using water-soluble redox-type polymerization initiators according to circumstances. Examples of the redox-based polymerization initiator include an oxidizing agent (such as the above-mentioned peroxide) and a reducing agent such as sodium bisulfite, ammonium bisulfite, ammonium sulfite, sodium hydrosulfite, or a combination of iron alum and potassium alum.

In the process of preparing water-soluble high molecular weight compounds, in order to adjust the molecular weight, a chain transfer agent may be appropriately added to the polymerization system. Examples of chain transfer agents include sodium phosphite, sodium hypophosphite, potassium hypophosphite, sodium sulfite, sodium bisulfite, thioglycolic acid, mercaptodiethyl keto acid, thioglycolic acid, 2-propanethiol, 2- Mercaptoethanol and thiophenol etc.

The polymerization temperature when preparing a water-soluble high molecular weight compound is not particularly limited, but it is preferably prepared when the polymerization temperature is 60 to 100°C. By setting the polymerization temperature to 60°C or higher, the polymerization reaction can proceed smoothly and the productivity is excellent, and by controlling it to 100°C or lower, coloring can be suppressed.

In addition, the polymerization reaction can be carried out under pressure or reduced pressure. However, the equipment for the pressure or reduced pressure reaction requires additional costs, so it is preferably carried out under normal pressure. The polymerization reaction time is preferably 2 to 20 hours, and particularly preferably 3 to 10 hours.

After the polymerization reaction, a basic compound can be used for neutralization as needed. Examples of the basic compound used in the neutralization reaction include: alkali metal hydroxides such as sodium hydroxide or potassium hydroxide, alkaline earth metal hydroxides such as calcium hydroxide and magnesium hydroxide, ammonia water, and monoethanolamine, diethanolamine, Organic amines such as triethanolamine.

In an aqueous solution with a water-soluble high molecular weight compound concentration of 10% by mass, medium The pH value (25°C) after the neutralization reaction or without the neutralization reaction is preferably 2 to 9, and more preferably 3 to 8.

(2-7) Weight average molecular weight

The polymer having a carboxylic acid group-based monomer as an essential monomer, the polymer having a sulfonic acid group-based monomer as an essential monomer, and the carboxylic acid group The monomers and monomers with sulfonic acid groups are copolymers of essential monomers, and the copolymers of monomers with carboxylic acid groups and monomers with sulfonic acid groups and monomers with amide groups are essential monomers The weight average molecular weight is preferably 1,000 or more and 1,000,000 or less, particularly preferably 3,000 or more and 800,000 or less, and more preferably 5,000 or more and 600,000 or less. In addition, the weight average molecular weight of the water-soluble high molecular weight compound is measured by gel permeation chromatography (GPC) in terms of polyacrylic acid. If the weight average molecular weight of the water-soluble high molecular weight compound is less than 1,000, the degree of dents after grinding will be deteriorated; while the weight average molecular weight of more than 10,000,000 will increase the viscosity of the aqueous solution and become difficult to handle.

(2-8) Concentration

The concentration of the water-soluble high molecular weight compound in the abrasive composition, when converted to solid content, is 0.0001 mass% or more and 3.0 mass% or less, preferably 0.001 mass% or more and 2.0 mass% or less, more preferably 0.005 mass% Above and below 1.0% by mass. If the concentration of the water-soluble high-molecular-weight compound is less than 0.0001% by mass, the effect of adding the water-soluble high-molecular-weight compound cannot be sufficiently obtained, and if the concentration is greater than 3.0% by mass, the effect of the addition of the water-soluble high-molecular-weight compound will reach the upper limit, so the addition of more than the necessary amount Water-soluble high molecular weight compounds have no economic effect.

(3) Organic sulfate ester compound

The abrasive composition of the present invention contains an organic sulfate ester salt compound as an essential component. As the organic sulfate ester salt compound, any one of the following first type and second type may be included.

(3-1) Organic sulfate salt compound (first type)

The first type of organic sulfate salt compound used in the abrasive composition of the present invention is a compound represented by the following general formula (1).

RO-SO ₃ M (1) In the formula, R represents a linear or branched alkyl, alkenyl, allyl or allyl alkyl group having 5 to 21 carbon atoms, and M represents an alkali metal, alkaline earth metal, ammonium Ion or organic cation.

In the above general formula (1), if the carbon number of R is less than 5, the dispersing and removing ability and re-adhesion preventing ability of the grinding debris generated by polishing may sometimes be insufficient. If the carbon number of R exceeds 21, the organic sulfate ester salt The solubility and dispersion stability of the compound itself in the abrasive composition will decrease. During the use of the abrasive composition, the solubility and dispersion stability may sometimes decrease. The carbon number of R is preferably from 8 to 14, more preferably from 10 to 14.

Specific examples of the alkyl group shown by R include pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecane Group, hexadecyl, octadecyl, nonadecyl, tert-butyl, isooctyl, isododecyl, etc. In addition, examples of alkenyl groups include oleoyl groups and the like. In addition, examples of allyl groups include phenyl, biphenyl, and naphthyl. In addition, examples of allyl groups include tolyl, xylyl, and octylphenol groups. From the viewpoint of oxidation stability and decomposition stability, R is preferably an alkyl group.

In the above general formula (1), examples of M include alkali metals such as sodium or potassium, alkaline earth metals such as calcium or magnesium, ammonium ions, quaternary ammonium ions, or organic amines such as triethanolamine.

Specific examples of the organic sulfate ester compound represented by the above general formula (1) include heptyl sulfate, octyl sulfate, lauryl sulfate, higher alcohol (coconut oil) sulfate, stearic sulfate, etc., among which preferably used Caprylic sulfate, laurel sulfate, stearate sulfate. Represented by the above general formula (1) The organic sulfate ester compound may be used alone or in combination of two or more in the abrasive composition of the present invention.

The content of the organic sulfate ester salt compound represented by the general formula (1) in the abrasive composition is usually 0.0001 to 2.0% by mass, preferably 0.0005 to 1.0% by mass.

(3-2) Organic sulfate ester compound (second type)

The second type of organic sulfate salt compound used in the abrasive composition of the present invention is a compound represented by the following general formula (2).

RO-(AO)n-SO ₃ M (2) In the formula, R represents a linear or branched alkyl, alkenyl, allyl or allyl alkyl group having 5 to 21 carbon atoms, and AO represents a carbon number of Oxyalkylene of 2 or 3, n represents a natural number from 1 to 30, M represents alkali metal, alkaline earth metal, ammonium ion or organic cation.

In the organic sulfate ester salt compound represented by the above general formula (2), R is a linear or branched alkyl group, alkenyl group, allyl group or allyl group having 5 to 21 carbon atoms. The carbon number of R is preferably from 8 to 14, more preferably from 10 to 14. In addition, R is preferably an alkyl group.

In the above general formula (2), AO is an oxyalkylene group having 2 or 3 carbon atoms.

In the above general formula (2), n is a natural number of 1 to 30, preferably 2 to 4.

In the above general formula (2), examples of M include alkali metals such as sodium or potassium, alkaline earth metals such as calcium or magnesium, ammonium ions, quaternary ammonium ions, or organic amines such as triethanolamine.

As the organic sulfate salt compound represented by the general formula (2), a well-known water-soluble compound is used as an anionic surfactant. In the present invention, the organic sulfate ester salt compound represented by the above general formula (2) refers to polyoxyalkylene ether sulfate salt, polyoxyalkylene ether ether sulfate salt, polyoxyalkylene aryl ether Sulfate salt and polyoxyalkylene alkyl aryl ether sulfate salt Any of them.

More specifically, examples of the organic sulfate ester compound represented by the above general formula (2) include polyoxyethylene tridecyl ether sulfate (2 or 3 polyoxyethylene groups per molecule), polyoxyethylene lauryl ether Sulfate (2 or 3 polyoxyethylene per molecule), polyoxyethylene nonyl ether sulfate (3 polyoxyethylene per molecule), polyoxyethylene octphenol ether sulfate (3 polyoxyethylene per molecule) Group), polyoxyethylene nonyl phenyl ether sulfate (3 polyoxyethylene groups per molecule), etc. Among them, the best is the use of polyoxyethylene tridecyl ether sulfate (3 polyoxyethylene per molecule), polyoxyethylene lauryl ether sulfate (3 polyoxyethylene per molecule), polyoxyethylene octyl phenol ether sulfate Salt (3 polyoxyethylene groups per molecule), polyoxyethylene nonoxyphenate sulfate (3 polyoxyethylene groups per molecule).

The organic sulfate ester salt compound represented by the above general formula (2) may contain one kind alone or two or more kinds in combination in the abrasive composition of the present invention. In addition, it can also be used in combination with the organic sulfate ester salt compound represented by the general formula (1).

The content of the organic sulfate ester salt compound represented by the above general formula (2) in the abrasive composition is usually 0.0001 to 2.0% by mass, preferably 0.0005 to 1.0% by mass.

(4) Acids and/or their salts

In the present invention, acids and/or their salts can be used to adjust pH or as a selective component. Examples of the acid and/or its salt used include inorganic acid and/or its salt and organic acid and/or its salt.

Examples of inorganic acids and/or salts thereof include inorganic acids such as nitric acid, sulfuric acid, hydrochloric acid, phosphoric acid, phosphonic acid, pyrophosphoric acid, and tripolyphosphoric acid and/or their salts.

Examples of organic acids and/or salts thereof include amino carboxyl such as glutamic acid or aspartic acid Acids and/or their salts, and carboxylic acids and/or their salts such as citric acid, tartaric acid, oxalic acid, nitroacetic acid, maleic acid, malic acid and succinic acid, organic phosphonic acids and/or their salts . These acids and/or their salts can be used alone or in combination of two or more.

Organic phosphonic acid and/or its salts are at least one compound selected from the group consisting of 2-aminoethylphosphonic acid, 1-hydroxyethylene-1,1-diphosphonic acid, and aminotri(methylene Phosphonic acid), ethylenediamine tetrakis (methylenephosphonic acid), diethylenetriamine penta (methylenephosphonic acid), ethane-1,1-diphosphonic acid, ethane-1,1,2 -Triphosphonic acid, ethane-1-hydroxy-1,1,2-triphosphonic acid, ethane-1,2-dicarboxy-1,2-diphosphonic acid, methanehydroxyphosphonic acid, 2-phosphonobutane Alkane-1,2-dicarboxylic acid, 1-phosphonobutane-2,3,4-tricarboxylic acid, α-methylphosphono succinic acid and salts thereof.

The above compounds are used in combination of two or more types, and may also be a preferred embodiment. Specific examples include a combination of sulfuric acid and/or its salts and organic phosphonic acid and/or its salts, phosphoric acid and/or its salts and organic phosphine Combination of acids and/or their salts, etc.

(5) Oxidizing agent

In the present invention, an oxidizing agent can be used as a grinding accelerator. Examples of the oxidizing agent used include peroxide, permanganic acid or its salts, chromic acid or its salts, peroxyacid or its salts, oxyhalic acid or its salts, oxyacid or its salts, and A mixture of two or more of these oxidants.

Specific examples include hydrogen peroxide, sodium peroxide, barium peroxide, potassium peroxide, potassium permanganate, metal salts of chromic acid, metal salts of dichromic acid, persulfuric acid, sodium persulfate, potassium persulfate, persulfate Ammonium, peroxyphosphoric acid, sodium peroxyborate, perforic acid, peracetic acid, hypochlorous acid, sodium hypochlorite, calcium hypochlorite, etc. Among them, hydrogen peroxide, persulfuric acid and its salts, hypochlorous acid and its salts, etc. are preferred, and hydrogen peroxide is more preferred.

The content of the oxidizing agent in the abrasive composition is preferably 0.01 to 10.0% by mass. especially It is preferably 0.1 to 5.0% by mass.

2. Physical properties (pH) of the abrasive composition

The abrasive composition of the present invention preferably has a pH value (25°C) in the range of 0.1 to 4.0, particularly preferably 0.5 to 3.0. By setting the pH value (25° C.) of the abrasive composition to 0.1 or more, the surface roughness can be suppressed. By setting the pH value (25° C.) of the abrasive composition to 4.0 or less, it is possible to suppress a decrease in the polishing rate.

The abrasive composition of the present invention can be used for polishing various electronic components such as hard disks and so-called magnetic recording media. In particular, it is suitable for polishing aluminum disk substrates. It is more suitable for the polishing of aluminum disk substrates made of electroless nickel-phosphorus plating. Electroless nickel-phosphorus electroplating is generally carried out under the conditions of pH value (25℃) 4.0~6.0. For electroplating conditions where the pH value (25°C) is less than 4.0, nickel tends to dissolve and electroplating will be difficult. On the other hand, during polishing, for example, under a pH value (25°C) of less than 4.0, nickel tends to dissolve, but the polishing rate can be increased by using the polishing composition of the present invention.

3. Grinding method of disk substrate

The abrasive composition of the present invention is suitable for polishing disk substrates such as aluminum disk substrates and glass disk substrates. Especially suitable for the polishing of electroless nickel-phosphorus plated aluminum magnetic disk substrates (hereinafter referred to as "aluminum disks").

As a polishing method applicable to the abrasive composition of the present invention, for example, a polishing pad is attached to a flat plate of a polishing machine, and at the same time, an abrasive composition is applied to the polishing surface or polishing pad of an object to be polished, such as an aluminum dish, The method of rubbing the surface with a polishing pad (called polishing). For example, when grinding the front and back of an aluminum dish at the same time, there is a method of using a double-sided grinding machine to grind the polishing pads attached to the upper and lower plates, respectively. In this method, the aluminum disc is clipped and attached to The polishing composition is applied between the polishing pads of the upper and lower plates, and between the polishing surface and the polishing pads, and the front and back sides of the aluminum dish are polished by the simultaneous rotation of the two polishing pads. The polishing pad can use polyurethane polishing pad, suede polishing pad, non-woven cloth polishing pad and any other material polishing pad.

[Example]

The present invention will be specifically described below based on embodiments, but the present invention is not limited to these embodiments, and can be implemented in various types without departing from the technical scope of the present invention.

Preparation method of abrasive composition

The abrasive compositions used in Examples 1 to 15 and Comparative Examples 1 to 9 were the abrasive compositions containing the materials described in Table 1 at the contents described in Table 1. In addition, the polishing test results of each example and each comparative example are shown in Table 2 and Table 3. In addition, polyoxyethylene tridecyl ether sodium sulfate is the second type of organic sulfate ester compound; sodium lauryl sulfate is the first type of organic sulfate ester compound. In addition, Synthesis Nos. 1 to 5 are water-soluble high molecular weight compounds of copolymers in which monomers having carboxylic acid groups and monomers having sulfonic acid groups are essential monomers. Synthetic numbers 6, 7 are homopolymers. In addition, in Examples 11 and 12, the water-soluble high molecular weight compound is a mixture containing a polymer having a monomer having a carboxylic acid group as an essential monomer and a polymer having a monomer having a sulfonic acid group as an essential monomer. Synthetic number 8 is a water-soluble high molecular weight compound of a copolymer in which a monomer having a carboxylic acid group, a monomer having a sulfonic acid group and a monomer having an amide group are essential monomers.

AA: Acrylic

ATBS: 2-Acrylamido-2-methylpropanesulfonic acid

TBAA: tert-butyl acrylamide

The average particle size

The average particle size of the alumina particles was measured using a laser diffraction particle size distribution measuring device (manufactured by Shimadzu Corporation, SALD 2200). The average particle size of alumina particles is the average particle size (D50) when the cumulative particle size distribution from the small particle size is 50% based on the volume.

Weight average molecular weight

The weight average molecular weight of the water-soluble high molecular weight compound is measured by gel permeation chromatography (GPC) in terms of polyacrylic acid. The GPC measurement conditions are shown below.

GPC conditions

Column: G4000PWXL (manufactured by Tosoh Corporation) + G2500PWXL (manufactured by Tosoh Corporation)

Eluent: 0.2M phosphate buffer/acetonitrile = 9/1 (capacity ratio)

Flow rate: 1.0mL/min

Temperature: 40℃

Detection: 210nm (UV)

Sample: concentration 5mg/mL (injection volume 100μL)

Standard curve polymer: Polyacrylic acid Molecular weight (peak molecular weight: Mp) 115,000, 28,000, 4100, 1250 (Chuanghe Science Co., Ltd., American Polymer Standards Corp.)

Grinding conditions

An aluminum dish with an outer diameter of 95 mm electroless nickel-phosphorus plating was used as the substrate for polishing, and the polishing was performed under the following polishing conditions.

Grinding machine: 9B double-sided grinding machine manufactured by SpeedFam Company Ltd.

Grinding pad: P1 pad manufactured by FILWEL CO.,LTD.

Rotation number of flat plate: upper plate-7.5min- ¹

Lower plate 22.5min- ¹

Supply amount of abrasive composition: 100ml/min

Grinding time: 4.5 minutes

Processing pressure: 100g/cm ²

The results of the polishing test under the above polishing conditions are shown in Table 2 and Table 3.

Grinding speed ratio

The grinding speed is the value of the aluminum disc that is reduced after grinding, and then calculated according to the following formula.

Grinding speed (μm/min)=Aluminum disc mass reduction (g)/grinding time (min)/aluminum disc single-sided area (cm ² )/electroless nickel-phosphorus plating density (g/cm ³ )/2× 10 ⁴

(However, in the above formula, the single-sided area of the aluminum dish is 65.9 cm ² , and the density of the electroless nickel-phosphorus plating film is 8.0 g/cm ³ )

The polishing rate ratio is a relative value obtained when the polishing rate of Comparative Example 1 is 1 (reference) obtained by the above formula, and the actual measured value of Comparative Example 1 is 0.354 μm/min.

Depression

The depressions of the aluminum dish were measured using a scanning white light three-dimensional surface structure analysis microscope manufactured by Ametek Co., Ltd. The measurement conditions used a measurement device (New View 8300 (lens: 1.4 times, magnification: 1.0 times) manufactured by Ametek Co., Ltd., with a wavelength of 500 to 1000 μm, a measurement range of 6 mm×6 mm, and Ametek Co., Ltd. Manufacturing analysis software (Mx) 行分析。 Line analysis. In addition, the numerical values shown in Table 2 and Table 3 are relative values when the degree of depression of Comparative Example 1 is 1 (reference). The measured value of Comparative Example 1 was 1.9Å.

Roll-off ratio

As an evaluation of the shape of the end face, the degree of sagging of the periphery showing the degree of roll-off numerically was measured. The roll-off was measured using a measurement device New View 8300 (lens: 1.4 times, magnification: 1.0 times) manufactured by Ametek Co., Ltd and analysis software (Mx) manufactured by Ametek Co., Ltd.

The measurement method of roll-off will be described with reference to FIG. 1. FIG. 1 is a vertical cross-sectional view of an electroless nickel-phosphorus electroplated aluminum dish with an outer diameter of 95 mm, which passes through the center of the dish to the grinding surface. When measuring roll-off, first set a vertical line H along the outer peripheral end of the disc. From the vertical line H to the center of the disc on the grinding surface, set a line j parallel to the vertical line H and the distance from the vertical line H to 3.90 mm. The intersection of the cross-sectional line and the line j is point A. In addition, a line k is provided at a distance parallel to the vertical line H and a distance of 0.30 mm from the vertical line H, and the point where the cross-section line of the disc intersects the line k is the point B. Set the line m connecting point A and point B, then set the line t perpendicular to line m, and take the intersection of the cross-section line of the disc and line t as point C, and the intersection of line m and line t as point D. Next, measure the maximum distance between points C-D and use this distance as the roll-off.

The roll-off ratio is a relative value when the roll-off ratio of Comparative Example 1 measured by the above method is 1 (reference). The measured value of Comparative Example 1 is 913Å.

AA: Acrylic

ATBS: 2-Acrylamido-2-methylpropanesulfonic acid

TBAA: tert-butyl acrylamide

330T: sodium polyoxyethylene tridecyl ether sulfate

LS-30: sodium laurel sulfate

In all examples and comparative examples, hydrogen peroxide: 0.6% by mass, sulfuric acid: 1.1% by mass (addition amount for pH=1.2)

AA: Acrylic

ATBS: 2-Acrylamido-2-methylpropanesulfonic acid

TBAA: tert-butyl acrylamide

330T: sodium polyoxyethylene tridecyl ether sulfate

LS-30: sodium laurel sulfate

In all examples and comparative examples, hydrogen peroxide: 0.6% by mass, sulfuric acid: 1.1% by mass (addition amount for pH=1.2)

in conclusion

Example 1 is an experiment in which an organic sulfate ester compound is added to Comparative Example 1, in which the polishing speed, dents, and roll-off are all improved. In addition, Example 1 is an experiment in which a water-soluble high-molecular-weight compound is added to Comparative Example 2, in which the polishing speed, dents, and roll-off are all improved. Next, Example 1 is an experiment in which a copolymer is used instead of a homopolymer as a water-soluble high-molecular-weight compound, as compared with Comparative Example 3. The polishing speed, dents, and roll-off are all improved. Example 2 is an experiment to change the molecular weight of the water-soluble high molecular weight compound of Example 1.

Example 3 is an experiment of adding an organic sulfate ester compound to Comparative Example 1, in which the grinding speed is equal, but both the dent and roll-off are improved. In addition, Example 3 is an experiment in which a water-soluble high-molecular-weight compound is added to Comparative Example 4, in which the polishing speed, dents, and roll-off are all improved. Next, Example 3 is an experiment using a copolymer instead of a homopolymer as a water-soluble high molecular weight compound, as compared to Comparative Example 5, in which the polishing speed, dents, and roll-off are all improved. Example 4 is an experiment to change the molecular weight of the water-soluble high molecular weight compound of Example 3.

Example 5 is an experiment in which an organic sulfate ester compound is added to Comparative Example 6, in which the grinding speed, dents, and roll-off are all improved. Example 6 is an experiment to change the molecular weight of the water-soluble high molecular weight compound of Example 5.

Example 7 is an experiment in which an organic sulfate ester salt compound is added to Comparative Example 6, in which the grinding speed, dents, and roll-off are all improved. Example 8 is an experiment to change the molecular weight of the water-soluble high molecular weight compound of Example 7.

Example 9 is an experiment using a copolymer instead of a homopolymer as a water-soluble high molecular weight compound, as compared to Comparative Example 7, in which the polishing speed, dents, and roll-off are all improved. Example 10 is an experiment in which a copolymer is used instead of a homopolymer as a water-soluble high-molecular-weight compound, as compared with Comparative Example 8, in which the polishing speed, dents, and roll-off are all improved.

Compared with Comparative Example 3, an experiment using only AA (acrylic acid) homopolymer as a water-soluble high molecular weight compound, Example 11 uses an AA homopolymer and ATBS (2-acrylamide-2-methylpropanesulfonic acid ) Experiments on mixtures of homopolymers, in which the grinding speed, dents and roll-off are all improved. In addition, Comparative Example 7 is an experiment using only ATBS homopolymer. In contrast, the polishing speed, dents, and roll-off of Example 11 are improved.

Compared with the experiment of using only AA homopolymers in Comparative Example 5, Example 12 is an experiment using a mixture of AA homopolymers and ATBS homopolymers, in which the grinding speed, dents, and roll-off are all improved. In addition, Comparative Example 8 is an experiment using only the ATBS homopolymer. In contrast, the polishing speed, dents, and roll-off of Example 12 are also improved.

Example 13 is an experiment in which an organic sulfate ester salt compound is added to Comparative Example 9, in which the grinding speed, dents, and roll-off are all improved.

Example 14 is an experiment in which the composition of the water-soluble high molecular weight compound used in Example 1 is changed, and a copolymer composed of three monomer components is used.

Example 15 is an experiment in which the composition of the water-soluble high molecular weight compound used in Example 3 is changed, and a copolymer composed of three monomer components is used.

From the above results, it is obvious that by using the abrasive composition of the present invention, the polishing speed, pitting, and roll-off phenomenon can be improved. According to the present invention, while maintaining the polishing speed, the degree of depression of the substrate surface can be reduced and the roll-off phenomenon can be reduced.

[Industry availability]

The abrasive composition of the present invention can be used for so-called magnetic recording of semiconductors, hard disks, etc. Grinding of various electronic components such as media. In particular, it can be used to polish the surface of substrates for magnetic recording media such as glass disk substrates and aluminum disk substrates. In addition, it can be used to polish the surface of an aluminum disk substrate for magnetic recording media where an electroless nickel-phosphorus plating film is formed on the surface of an aluminum alloy substrate.

A, B, C, D ‧‧‧ points

h‧‧‧Vertical

j, k, m, t ‧‧‧ line

Claims (11)

An abrasive composition for a magnetic disk substrate, comprising: alumina particles; a water-soluble high molecular weight compound; an organic sulfate ester compound; and water, wherein the water-soluble high molecular weight compound is a monomer containing a carboxylic acid group Mixture of polymers with essential monomers and polymers with monomers with sulfonic acid groups as essential monomers, and/or with monomers with carboxylic acid groups and monomers with sulfonic acid groups as essential monomers Copolymer, and the organic sulfate ester compound is represented by the following general formula (1) RO-SO ₃ M (1) In the formula, R represents a linear or branched alkyl group, alkenyl group having 5 to 21 carbon atoms, Allyl or allyl, M represents alkali metal, alkaline earth metal, ammonium ion or organic cation. An abrasive composition for a magnetic disk substrate, comprising: alumina particles; a water-soluble high molecular weight compound; an organic sulfate ester compound; and water; wherein the water-soluble high molecular weight compound is a monomer containing a carboxylic acid group Mixture of polymers with essential monomers and polymers with monomers with sulfonic acid groups as essential monomers, and/or with monomers with carboxylic acid groups and monomers with sulfonic acid groups as essential monomers Copolymer, and the organic sulfate ester salt compound is represented by the following general formula (2) RO-(AO) _n -SO ₃ M (2) In the formula, R represents a linear or branched alkane with a carbon number of 5 to 21 Group, alkenyl, allyl or allyl group, AO represents an oxyalkylene group with a carbon number of 2 or 3, n represents a natural number from 1 to 30, M represents an alkali metal, alkaline earth metal, ammonium ion or organic cation . The abrasive composition for a magnetic disk substrate as described in item 1 or 2 of the patent application scope, wherein the water-soluble high molecular weight compound uses monomers having a carboxylic acid group and monomers having a sulfonic acid group as essential monomers The copolymer is a copolymer in which a monomer having a carboxylic acid group, a monomer having a sulfonic acid group and a monomer having an amide group are essential monomers. The abrasive composition for a magnetic disk substrate as described in item 1 or 2 of the patent application range, wherein the alumina particles contain α-alumina and the average particle diameter is 0.1-2.0 μm, and the The concentration is 1-50% by mass. The abrasive composition for a magnetic disk substrate as described in item 1 or 2 of the patent application scope, wherein the single system having a carboxylic acid group is selected from monomers of acrylic acid or its salts, methacrylic acid or its salts . The abrasive composition for a magnetic disk substrate as described in item 1 or 2 of the patent application range, wherein the single system with a sulfonic acid group is selected from isoprenesulfonic acid, 2-propenamide-2-methyl Propylsulfonic acid, 2-methacrylamide-2-methylpropanesulfonic acid, styrenesulfonic acid, ethylenesulfonic acid, propylenesulfonic acid, isopentenylsulfonic acid, ethylene naphthalenesulfonic acid and one of its salts Or more than two monomers. The abrasive composition for a magnetic disk substrate as described in item 3 of the patent application range, wherein the single system with an amide group is selected from acrylamide, methacrylamide, N-alkylacrylamide, N -Alkyl methacrylamide monomer. The abrasive composition for a magnetic disk substrate as described in item 1 or 2 of the patent application scope, wherein the polymer having the monomer having a carboxylic acid group as an essential monomer, and the monomer having a sulfonic acid group are Mandatory Polymers, copolymers in which the monomer having a carboxylic acid group and a monomer having a sulfonic acid group are essential monomers, and the monomer having a carboxylic acid group and a monomer having a sulfonic acid group The amine-based monomers are copolymers of essential monomers each having a weight average molecular weight of 1,000 or more and 1,000,000 or less. The abrasive composition for a magnetic disk substrate as described in item 1 or 2 of the patent application range, wherein the abrasive composition further contains an acid and/or its salts, and the pH value (25°C) ranges from 0.1 to 4.0 . The abrasive composition for a magnetic disk substrate as described in item 1 or 2 of the patent application range, wherein the abrasive composition further contains an oxidizing agent. The abrasive composition for a magnetic disk substrate as described in item 1 or 2 of the patent application scope is used for polishing an electroless nickel-phosphorus plated aluminum magnetic disk substrate.

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