TWI811414B - Polishing composition for magnetic disk substrate - Google Patents

Abstract

An abrasive composition is provided that can maintain the polishing speed and at the same time reduce the dent and roll-off phenomena of the substrate after polishing. The abrasive composition is an aqueous composition containing at least alumina particles, a water-soluble polymer compound, and an organic sulfate ester salt compound. Here, the water-soluble polymer compound is 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, and/or a mixture of Monomers with carboxylic acid groups and monomers with sulfonic acid groups are copolymers of essential monomers.

Description

Abrasive composition for disk substrates

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

Traditionally, from the viewpoint of production efficiency, as an abrasive composition for polishing the surface of the electroless nickel-phosphorus plating film of an aluminum disk substrate, alumina particles that can achieve a high polishing speed have been used with water. Dispersed abrasive composition.

In order to increase the grinding speed, reduce dents and reduce roll-off phenomena, it is proposed to use alumina particles with various crystal structures in abrasive compositions using alumina-based abrasive particles to increase the grinding speed and reduce dents and roll-off phenomena. A solution that coexists with high grinding surface quality such as phenomena.

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

Patent Document 2 proposes a method of reducing the degree of surface depression and increasing the polishing speed by using an abrasive composition containing aluminum oxide other than α-alumina, that is, intermediate alumina.

Patent Document 3 proposes a solution to achieve high polishing speed and reduce dents by using an abrasive composition containing α-alumina and intermediate alumina. However, the dent reduction effect is not sufficient, and improvements are being sought.

In Patent Document 4, it is proposed that when polishing a magnetic recording medium substrate using an abrasive composition containing abrasives, grinding aids and water, an aliphatic organic sulfate can be used as a grinding aid to increase the polishing speed and improve the stability of the magnetic recording medium substrate. Solution to reduce surface roughness. However, this solution is not sufficient for increasing the grinding speed and reducing surface roughness, and improvements are being sought.

[Prior technical literature]

patent documents

Patent document 1: Japanese Patent Application Laid-Open No. 11-268911

Patent document 2: Japanese Patent Application Publication No. 2001-89746

Patent Document 3: Japanese Patent Application Publication No. 2005-23266

Patent Document 4: International Publication No. 1998/021289

However, as described in Patent Documents 1 to 4, if a polishing composition containing intermediate alumina is used to polish the disk substrate, problems such as deterioration of post-polishing dents and lower product quality will occur.

The subject of the present invention is to maintain the polishing speed and reduce the degree of depression and roll-off phenomenon of the polished substrate.

In view of the above-mentioned problems, the present inventors devoted themselves to research on 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] A polishing composition for magnetic disk substrates containing alumina particles, a water-soluble polymer compound, an organic sulfate ester salt compound, and water. The water-soluble polymer compound is 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, and/or a mixture having a monomer having a carboxylic acid group as an essential monomer. The monomer with carboxylic acid group and the monomer with sulfonic acid group 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) where, R Represents a linear or branched alkyl, alkenyl, allyl or allyl group with a carbon number of 5 to 21, and M represents an alkali metal, alkaline earth metal, ammonium ion or organic cation.

[2] A polishing composition for magnetic disk substrates containing alumina particles, a water-soluble polymer compound, an organic sulfate ester salt compound, and water. The water-soluble polymer compound is 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, and/or a mixture having a monomer having a carboxylic acid group as an essential monomer. The monomer with carboxylic acid group and the monomer with sulfonic acid group 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, alkenyl, allyl or allyl group with a carbon number of 5 to 21, AO represents an oxyalkylene group with a carbon number of 2 or 3, and n represents 1 to A natural number of 30, M represents an alkali metal, alkaline earth metal, ammonium ion or organic cation.

[3] The abrasive composition for disk substrates as described in [1] or [2] above, wherein the water-soluble polymer compound is composed of a monomer having a carboxylic acid group and a monomer having a sulfonic acid group. The copolymer of essential monomers is a copolymer containing a monomer with a carboxylic acid group, a monomer with a sulfonic acid group and a monomer with an amide group as essential monomers.

[4] The abrasive composition for magnetic disk substrates according to any one of the above [1] to [3], 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 to 50% by mass.

[5] The abrasive composition for magnetic disk substrates according to any one of the above [1] to [4], wherein the monosystem having a carboxylic acid group is selected from the group consisting of acrylic acid or its salts, methacrylic acid or Monomers of its salts.

[6] The abrasive composition for magnetic disk substrates according to any one of the above [1] to [5], wherein the monosystem having a sulfonic acid group is selected from the group consisting of isoprene sulfonic acid and 2-propylene. Amido-2-methylpropanesulfonic acid, 2-methacrylamide-2-methylpropanesulfonic acid, styrenesulfonic acid, ethylenesulfonic acid, propylenesulfonic acid, isopentenesulfonic acid, vinylnaphthalenesulfonic acid And one or more than two monomers of its salts.

[7] The abrasive composition for disk substrates as described in the above [3], wherein the monosystem having an amide group is selected from the group consisting of acrylamide, methacrylamide, N-alkyl acrylamide, Monomer of N-alkyl methacrylamide.

[8] The abrasive composition for magnetic disk substrates according to any one of the above [1] to [7], wherein the monomer having a carboxylic acid group is a polymer that is an essential monomer, and the monomer having a sulfonate group is a polymer. Polymers in which the monomer with an acid group is an essential monomer, copolymers in which the monomer with a carboxylic acid group and a monomer with a sulfonic acid group are essential monomers, and copolymers in which the monomer with a carboxylic acid group and a monomer with a sulfonic acid group are essential monomers The weight average molecular weight of the copolymer in which the acid group monomer and the amide group-containing monomer are essential monomers is each between 1,000 and 1,000,000.

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

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

[11] The abrasive composition for magnetic disk substrates according to any one of the above [1] to [10], used for polishing electroless nickel-phosphorus electroplated aluminum magnetic disk substrates.

The abrasive composition for magnetic disk substrates 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 line

j, k, m, t: line

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

The following describes the embodiments of the present invention, but the present invention is not limited to the following embodiments. Those with ordinary knowledge in the technical field to which the present invention belongs can make appropriate changes and improvements to the following embodiments without departing from the scope of the invention. etc., and still belong to the scope of the present invention.

1. Abrasive composition

The abrasive composition of the present invention is an aqueous composition containing at least alumina particles, a water-soluble polymer compound, and an organic sulfate ester salt compound. Here, the water-soluble polymer compound is 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, and/or a mixture of Monomers with carboxylic acid groups and monomers with sulfonic acid groups It is a copolymer of essential monomers.

(1)Alumina particles

The colloidal silicon oxide contained in the abrasive composition for disk substrates of the present invention preferably has an average particle size (D50) of 5 to 200 nm. By setting the average particle diameter (D50) to 5 nm or more, a decrease in the polishing speed can be suppressed. By setting the average particle diameter (D50) to 200 nm or less, deterioration of surface smoothness can be suppressed. The average particle size (D50) of colloidal silicon oxide is preferably 10~150nm, especially 20~120nm.

Raw materials for preparing alumina include gibbsite: Al ₂ O ₃ ‧3H ₂ O, diaspore: Al ₂ O ₃ ‧H ₂ O, and diaspore: Al ₂ O ₃ ‧nH ₂ O(n=1~2) etc. The alumina raw materials can be prepared in the following manner, for example.

Gibbsite: Al ₂ O ₃ ‧3H ₂ O

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

Diaspore: Al ₂ O ₃ ‧H ₂ O

Aluminum alkoxide: Al(OR) ₃ obtained by reacting metal aluminum with ethanol is hydrolyzed to obtain diaspore.

Diaspore: Al ₂ O ₃ ‧nH ₂ O(n=1~2)

After treating the gibbsite with water vapor under an alkaline ambient gas, a gibbsite-like stone can be obtained.

After the alumina raw materials are fired, α-alumina, γ-alumina, δ-alumina, θ-alumina, etc. can be obtained.

The average particle size (D50) of alumina particles is preferably 0.1~2.0μm, especially is 0.2~1.0μm. By setting the average particle diameter of the alumina particles to 0.1 μm or more, a decrease in the polishing speed can be suppressed. By setting the average particle diameter of the alumina particles to 2.0 μm or less, deterioration of the degree of depression after polishing can be suppressed.

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

(2) Water-soluble polymer compounds

The water-soluble polymer compound used in the present invention is a mixture containing 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 The monomer with carboxylic acid group and the monomer with sulfonic acid group are copolymers of essential monomers. In addition, monomers other than these may also be used. Examples of the monomer other than the monomer having a carboxylic acid group and the monomer having a sulfonic acid group include a monomer having a amide group.

(2-1) Monomers with carboxylic acid groups

As the monomer having a carboxylic acid group, unsaturated aliphatic amide and its salts are preferably used. More specifically, acrylic acid, methacrylic acid, maleic acid, itaconic acid, and salts thereof are included. Examples of salts include sodium salts, potassium salts, magnesium salts, ammonium salts, amine salts, alkylammonium salts, and the like.

Among water-soluble polymer compounds, the pH value of water-soluble polymer compounds can be evaluated based on whether the proportion of monomers with carboxylic acid groups that exist in the acid state is greater, or whether the monomers that have carboxylic acid groups exist in the salt state. . The higher the proportion of acid present, the lower the pH value becomes; the higher the proportion of salt present, the higher the pH value becomes. In the present invention, for example, in an aqueous solution with a water-soluble polymer compound concentration of 10% by mass, a pH value (25°C) in the range of 0.1 to 13 can be used. Surrounded by water-soluble polymer compounds.

(2-2) Monomers with sulfonic acid groups

Specific examples of the monomer having a sulfonic acid group include isoprene sulfonic acid, 2-acrylamide-2-methylpropanesulfonic acid, and 2-methacrylamide-2-methylpropanesulfonic acid. , styrene sulfonic acid, ethylene sulfonic acid, propylene sulfonic acid, isopentenesulfonic acid, vinyl naphthalene sulfonic acid and their salts, etc. One or two or more types of these can be selected and used as a single substance. Preferred examples include 2-acrylamide-2-methylpropanesulfonic acid, 2-methacrylamide-2-methylpropanesulfonic acid, and salts thereof.

(2-3)Other monomers

The water-soluble polymer compound used in the present invention uses a monomer having a carboxylic acid group and a monomer having a sulfonic acid group as essential monomers, but monomers other than these may also be used. For example, monomers having amide groups can also be used. Specifically, acrylamide, methacrylamide, N-alkyl acrylamide, N-alkyl methacrylamide, etc. can be used.

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

(2-4)Polymer mixture

The water-soluble polymer compound used in the present invention may also be a mixture containing 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. The situation In this case, as the polymer constituting the mixture, as the polymer containing a monomer having a carboxylic acid group as an essential monomer, a polymer obtained by polymerizing a monomer having a carboxylic acid group, a monomer having a carboxylic acid group, etc. Copolymers of monomers with sulfonic acid groups, copolymers of monomers with carboxylic acid groups and other monomers, copolymers of monomers with carboxylic acid groups, monomers with sulfonic acid groups and other monomers wait.

In addition, examples of the polymer containing a monomer having a sulfonic acid group as an essential monomer include 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 of monomers, copolymers of monomers with sulfonic acid groups and other monomers, copolymers of monomers with carboxylic acid groups, monomers with sulfonic acid groups and other monomers, etc.

Mixtures containing polymers containing monomers with carboxylic acid groups as essential monomers and polymers containing monomers with sulfonic acid groups as essential monomers are derived from those containing monomers with carboxylic acid groups as essential monomers. A mixture of more than one polymer each of polymers containing monomers and polymers containing monomers with sulfonic acid groups as essential monomers. In the mixture, the proportion of the polymer in which the monomer with a carboxylic acid group is an essential monomer is preferably 5 to 95 mass %, more preferably 8 to 92 mass %, and more preferably 10 to 90 mass %. In the mixture, the proportion of the polymer in which the monomer with a sulfonic acid group is an essential monomer is preferably 5 to 95 mass %, more preferably 8 to 92 mass %, and more preferably 10 to 90 mass %.

(2-5)Copolymer

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

(2-6) Preparation method of water-soluble polymer compounds

Although the method for preparing the water-soluble polymer compound is not particularly limited, an aqueous solution polymerization method is preferred. Through the aqueous solution polymerization method, a uniform solution can be formed to obtain a water-soluble polymer compound. The polymerization solvent in the above aqueous solution polymerization is preferably an aqueous solvent, particularly water. In addition, in order to improve the solubility of the above-mentioned monomer components in the solvent, an organic solvent can be appropriately added within the 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. The above-mentioned solvents may be used alone or in combination of two or more.

The following describes the preparation method of the water-soluble polymer compound using the above-mentioned aqueous solvent. During the polymerization reaction, well-known polymerization initiators can be used, and a free radical polymerization initiator is particularly preferred. Examples of radical polymerization initiators include persulfates such as sodium persulfate, potassium persulfate, and ammonium persulfate; hydroperoxides such as tert-butyl hydroperoxide; water-soluble peroxides such as hydrogen peroxide; Methyl ethyl ketone peroxide, cyclohexanone peroxide and other ketone peroxides; oils such as di-tert-butyl peroxide, tert-butylcumyl peroxide and other dialkyl peroxides Soluble peroxide; azo compounds such as azobisisobutyronitrile, 2,2-azobis(2-methylpropionamidine)dihydrochloride. Only one type of peroxide radical polymerization initiator may be used, or two or more types may be used in combination. Among the above-mentioned peroxide radical polymerization initiators, from the viewpoint of easy control of the molecular weight of the produced water-soluble polymer compound, persulfate or azo compound is preferred, and azobis is particularly preferred. Isobutyronitrile.

Although the amount of the above-mentioned free radical polymerization initiator is not particularly limited, based on the total mass of all monomers of the water-soluble polymer compound, it is preferably used in a proportion of 0.1 to 15 mass %, and particularly preferably 0.5 Use the ratio of ~10% by mass. By increasing the ratio to more than 0.1 mass%, the copolymerization rate can be increased, and controlling the ratio below 15 mass% can improve the stability of the water-soluble polymer compound.

In addition, depending on the situation, the water-soluble polymer compound can be prepared using a water-soluble redox polymerization initiator. Examples of the redox 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 polymer compounds, in order to adjust the molecular weight, a chain transfer agent can 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, mercaptodiethylketo acid, thioglycolic acid, 2-propanethiol, 2- Mercaptoethanol and thiophenol, etc.

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

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

After the polymerization reaction, a basic compound can be used for neutralization reaction if necessary. Examples of alkaline compounds 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, etc.

In an aqueous solution with a water-soluble polymer compound concentration of 10% by mass, the pH value (25°C) after neutralization or when no neutralization reaction is performed is preferably 2 to 9, and more preferably 3 to 8.

(2-7) Weight average molecular weight

The water-soluble polymer compound used in the present invention contains a monomer having a carboxylic acid group as an essential monomer. Polymers of monomers, polymers containing monomers with sulfonic acid groups as essential monomers, and copolymers containing monomers with carboxylic acid groups and monomers with sulfonic acid groups as essential monomers, containing carboxylic acid The weight average molecular weight of the copolymer in which the monomer with a sulfonic acid group and the monomer with an amide group are essential monomers is preferably 1,000 or more and 1,000,000 or less, particularly preferably 3,000 or more and 800,000 or less. , preferably more than 5,000 and less than 600,000. In addition, the weight average molecule of the water-soluble polymer compound is measured by gel permeation chromatography (GPC) in terms of polyacrylic acid. If the weight average molecular weight of the water-soluble polymer compound is less than 1,000, the degree of denting after grinding will worsen; if the weight average molecular weight exceeds 10,000,000, the viscosity of the aqueous solution will increase, making it difficult to handle.

(2-8)Concentration

The concentration of the water-soluble polymer compound in the abrasive composition, when converted in terms of 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 % More than and 1.0 mass% or less. If the concentration of the water-soluble polymer compound is less than 0.0001% by mass, the effect of adding the water-soluble polymer compound cannot be fully obtained. If the concentration is greater than 3.0% by mass, the effect of adding the water-soluble polymer compound will reach the upper limit, so add more than the necessary amount. Water-soluble polymer compound, no economical effect.

(3) Organic sulfate ester salt compounds

The abrasive composition of the present invention contains an organic sulfate ester salt compound as an essential component. The organic sulfate ester salt compound may include any of the following first and second forms.

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

The first form of the organic sulfate ester 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 group with a carbon number of 5 to 21, and M represents an alkali metal, alkaline earth metal, ammonium ionic or organic cations.

In the above general formula (1), if the number of carbon atoms in R is less than 5, the dispersion and removal ability of grinding dust generated by grinding and the ability to prevent re-adhesion may be insufficient. If the number of carbon atoms in 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 8 to 14, more preferably 10 to 14.

Specific examples of the alkyl group represented by R include pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, and pentadecyl Base, hexadecyl, octadecyl, nonadecyl, tert-butyl, isooctyl, isododecanyl, etc. Examples of the alkenyl group include an oleyl group and the like. Furthermore, examples of allyl groups include phenyl group, biphenyl group, naphthyl group, and the like. Furthermore, examples of the allyl group include tolyl group, xylyl group, octylphenol group, and the like. From the viewpoint of oxidation stability, decomposition stability, etc., 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 salt compound represented by the above general formula (1) include heptyl sulfate, octyl sulfate, lauryl sulfate, higher alcohol (coconut oil) sulfate, stearyl sulfate, etc., among which it is preferred to use Octyl sulfate, lauryl sulfate, stearyl sulfate. In the abrasive composition of the present invention, one type of organic sulfate ester salt compound represented by the above-mentioned general formula (1) can be used alone, or two or more types can be used in combination.

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

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

The second form of the organic sulfate ester salt compound used in the polishing 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 group with a carbon number of 5 to 21, and AO represents a carbon number of Oxyalkylene group 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 8 to 14, more preferably 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 from 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 ester 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 compound represented by the above general formula (2) refers to polyoxyalkylene ether sulfate ester salt, polyoxyalkylene alkenyl ether sulfate ester salt, polyoxyalkylene aryl ether Any of sulfate ester salts and polyoxyalkylene alkylaryl ether sulfate ester salts.

More specifically, examples of the organic sulfate ester salt compound represented by the general formula (2) include polyoxyethylene tridecyl ether sulfate (2 or 3 polyoxyethylene groups per molecule), polyoxyethylene tridecyl ether sulfate, Oxyethylene lauryl ether sulfate (2 or 3 polyoxyethylene groups per molecule), polyoxyethylene nonyl ether sulfate (3 polyoxyethylene groups per molecule), polyoxyethylene octylphenol ether sulfate (3 polyoxyethylene groups per molecule) polyoxyethylene groups), polyoxyethylene nonylphenyl ether sulfate (3 polyoxyethylene groups per molecule), etc. Among them, polyoxyethylene tridecyl ether sulfate (3 polyoxyethylene groups per molecule), polyoxyethylene lauryl ether sulfate (3 polyoxyethylene groups per molecule), and polyoxyethylene octylphenol ether sulfate are particularly preferred. Salt (3 polyoxyethylene groups per molecule), polyoxyethylene nonylphenyl ether sulfate (3 polyoxyethylene groups per molecule).

The abrasive composition of the present invention may contain one type of organic sulfate ester salt compound represented by the above-mentioned general formula (2) alone, or a combination of two or more types thereof. In addition, it can also be used in combination with the organic sulfate ester salt compound represented by the above-mentioned 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 mass%, preferably 0.0005 to 1.0 mass%.

(4)Acid and/or its salts

In the present invention, acids and/or salts thereof may be used to adjust the pH value or as an optional ingredient. Examples of acids and/or salts thereof used include inorganic acids and/or salts thereof and organic acids and/or salts thereof.

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 salts thereof.

Examples of organic acids and/or salts thereof include aminocarboxylic acids such as glutamic acid or aspartic acid and/or salts thereof, as well as citric acid, tartaric acid, oxalic acid, nitroacetic acid, maleic acid, and malic acid. acid, succinic acid and other carboxylic acids and/or their salts, organic phosphonic acids and/or their salts. These acids and/or their salts can be used individually by 1 type, or in combination of 2 or more types.

Organic phosphonic acid and/or its salts are at least one compound selected from the following: 2-aminoethylphosphonic acid, 1-hydroxyethylene-1,1-diphosphonic acid, aminotris(methylene methylphosphonic acid), ethylenediaminetetrakis(methylenephosphonic acid), diethylenetriaminepenta(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-phosphonidine Alkane-1,2-dicarboxylic acid, 1-phosphonobutane-2,3,4-tricarboxylic acid, α-methylphosphonosuccinic acid and their salts.

It is also a preferred embodiment to use two or more of the above compounds in combination. 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 an organic phosphine. Combinations 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 oxidants used include peroxides, permanganic acid or its salts, chromic acid or its salts, peroxyacids or its salts, halogen acids or their salts, oxyacids or their salts, and Mixtures of two or more such oxidants, etc.

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 perborate, performic 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 oxidizing agent content in the abrasive composition is preferably 0.01 to 10.0 mass%. Especially preferably, it is 0.1~5.0% by mass.

2. Physical properties (pH) of the abrasive composition

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

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

3. Polishing method of disk substrate

The abrasive composition of the present invention is suitable for polishing magnetic disk substrates such as aluminum magnetic disk substrates and glass magnetic disk substrates. It is particularly suitable for grinding electroless nickel-phosphorus electroplated aluminum 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 the flat plate of a grinding machine, and the abrasive composition is applied to the polishing surface of the polishing object (such as an aluminum disc) or the polishing pad at the same time. The method of rubbing the surface with a polishing pad (called polishing). For example, when grinding the front and back sides of an aluminum disc at the same time, there is a method of using a double-sided grinder and grinding pads attached to the upper and lower plates respectively. In this method, an aluminum disc is sandwiched between polishing pads attached to the upper and lower flat plates, and an abrasive composition is applied between the polishing surface and the polishing pads by rotating the two polishing pads simultaneously. , grinding the front and back of the aluminum disc. Polishing pads can use polyurethane polishing pads, suede polishing pads, non-woven polishing pads and any other material. Sanding pad.

[Example]

The present invention will be specifically described below based on the embodiments. However, the present invention is not limited to these embodiments and can be implemented in various forms 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 are abrasive compositions containing the materials described in Table 1 in the contents described in Table 1. In addition, the grinding test results of each Example and each Comparative Example are shown in Table 2 and Table 3. In addition, sodium polyoxyethylene tridecyl sulfate is the second type of organic sulfate ester salt compound; sodium lauryl sulfate is the first type of organic sulfate ester salt compound. In addition, synthesis numbers 1 to 5 are water-soluble polymer compounds of copolymers using monomers with carboxylic acid groups and monomers with sulfonic acid groups as essential monomers. Synthesis numbers 6 and 7 are homopolymers. Furthermore, in Examples 11 and 12, the water-soluble high molecular weight compound is a mixture containing 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. Synthesis No. 8 is a water-soluble polymer compound that is a copolymer of a monomer with a carboxylic acid group, a monomer with a sulfonic acid group, and a monomer with an amide group as essential monomers.

AA: acrylic

ATBS: 2-Acrylamide-2-methylpropanesulfonic acid

TBAA: tert-butylacrylamide

average particle size

The average particle diameter of the alumina particles was measured using a laser diffraction particle size distribution analyzer (SALD2200, manufactured by Shimadzu Corporation). The average particle size of alumina particles is the average particle size (D50) corresponding to when the cumulative particle size distribution starting from the small particle size is 50% based on volume.

weight average molecular weight

The weight average molecular weight of a water-soluble polymer compound is measured by gel permeation chromatography (GPC) in terms of polyacrylic acid. The GPC measurement conditions are as follows.

GPC conditions

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

Eluate: 0.2M phosphate buffer/acetonitrile=9/1 (volume ratio)

Flow rate: 1.0mL/min

Temperature: 40℃

Detection: 210nm(UV)

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

Polymer for standard curve: polyacrylic acid, molecular weight (peak molecular weight: Mp) 115,000, 28,000, 4100, 1250 (Chuangwa Science Co., Ltd., American Polymer Standards Corp.)

Grinding conditions

An electroless nickel-phosphorus electroplated aluminum disc with an outer diameter of 95 mm was used as the substrate to be polished, and polishing was carried out under the following polishing conditions.

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

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

Number of plate rotations: Upper plate -7.5min- ¹

Lower the plate 22.5min- ¹

Abrasive composition supply volume: 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 measured by measuring the mass of the aluminum disc reduced after grinding, and then calculating the value based on the following formula.

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

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

The polishing speed ratio is a relative value when the polishing speed of Comparative Example 1 is 1 (standard) calculated by the above mathematical formula. The actual measured value of Comparative Example 1 is 0.354 μm/min.

depression

The dents of the aluminum disc were measured using a scanning white light three-dimensional surface structure analysis microscope manufactured by Ametek Co., Ltd. The measurement conditions are a measurement device (New View 8300 (lens: 1.4x, magnification: 1.0x) manufactured by Ametek Co., Ltd., a wavelength of 500~1000 μm, a measurement range of 6mm×6mm, and Ametek Co., Ltd. Manufacturing analysis software (Mx) Perform analysis. In addition, the numerical values shown in Table 2 and Table 3 are relative values when the degree of dent in Comparative Example 1 is 1 (standard). The actual measured value in Comparative Example 1 was 1.9Å.

roll-off ratio

As an evaluation of the end surface shape, the degree of peripheral sag, which represents the degree of roll-off numerically, is measured. The roll-off was measured using the measurement device New View 8300 (lens: 1.4x, magnification: 1.0x) manufactured by Ametek Co., Ltd. and the analysis software (Mx) manufactured by Ametek Co., Ltd.

The measurement method of roll-off is explained with reference to Figure 1. Figure 1 is a vertical cross-sectional view of an electroless nickel-phosphorus electroplated aluminum disc with an outer diameter of 95 mm, which is the target object for grinding, and passes through the center of the disc to the grinding surface. When measuring the roll-off, first set a vertical line H along the outer peripheral end of the disc, set a line j parallel to the vertical line H and 3.90mm away from the vertical line H from the vertical line H toward the center of the disc on the grinding surface, and take the disc The intersection of the section line and line j is point A. In addition, set a line k parallel to the vertical line H and at a distance of 0.30 mm from the vertical line H, and take the intersection of the disc's section line and the line k as point B. Set a line m connecting point A and point B, and then set a line t perpendicular to line m. The intersection of the disc's cross-section line and line t is point C, and the intersection of line m and line t is 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 (standard). The measured value of Comparative Example 1 is 913Å.

AA: acrylic

ATBS: 2-Acrylamide-2-methylpropanesulfonic acid

TBAA: tert-butylacrylamide

330T: polyoxyethylene sodium tridecyl ether sulfate

LS-30: Sodium Laurel Sulfate

In all Examples and Comparative Examples, hydrogen peroxide: 0.6 mass% and sulfuric acid: 1.1 mass% (the amount added to make pH=1.2) were added.

AA: acrylic

ATBS: 2-Acrylamide-2-methylpropanesulfonic acid

TBAA: tert-butylacrylamide

330T: polyoxyethylene sodium tridecyl ether sulfate

LS-30: Sodium Laurel Sulfate

In all Examples and Comparative Examples, hydrogen peroxide: 0.6 mass% and sulfuric acid: 1.1 mass% (the amount added to make pH=1.2) were added.

Conclusion

Compared to Comparative Example 1, Example 1 was an experiment in which an organic sulfate ester salt compound was added, in which the grinding speed, dents, roll-off, etc. were all improved. In addition, compared to Comparative Example 2, Example 1 was an experiment in which a water-soluble polymer compound was added, and the polishing speed, denting, roll-off, etc. were all improved. Next, compared to Comparative Example 3, Example 1 is an experiment in which a copolymer is used instead of a homopolymer as the water-soluble polymer compound, and the grinding speed, denting, roll-off, etc. are all improved. Example 2 is an experiment in which the molecular weight of the water-soluble polymer compound in Example 1 was changed.

Example 3 is an experiment in which an organic sulfate ester compound is added compared to Comparative Example 1. The grinding speed is the same, but the dent and roll-off are improved. In addition, compared to Comparative Example 4, Example 3 is an experiment in which a water-soluble polymer compound is added, in which the grinding speed, denting, roll-off, etc. are all improved. Next, Example 3 is an experiment in which a copolymer is used instead of a homopolymer as the water-soluble polymer compound compared to Comparative Example 5, in which the grinding speed, denting, roll-off, etc. are all improved. Example 4 is an experiment in which the molecular weight of the water-soluble polymer compound in Example 3 was changed.

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

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

Compared to Comparative Example 7, Example 9 is an experiment in which a copolymer was used instead of a homopolymer as the water-soluble polymer compound, and the grinding speed, denting, roll-off, etc. were all improved. Compared to Comparative Example 8, Example 10 uses a copolymer instead of a homopolymer as the water-soluble polymer. In experiments with sub-compounds, the grinding speed, dent and roll-off were all improved.

Compared to Comparative Example 3, which only uses AA (acrylic acid) homopolymer as the water-soluble polymer compound, Example 11 uses AA homopolymer and ATBS (2-acrylamide-2-methylpropanesulfonic acid). ) Experiments on homopolymer mixtures, in which the grinding speed, dent and roll-off were all improved. In addition, Comparative Example 7 is an experiment using only ATBS homopolymer. In contrast, Example 11 has improvements in grinding speed, denting, roll-off, etc.

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

Compared to Comparative Example 9, Example 13 was an experiment in which an organic sulfate ester salt compound was added, in which the grinding speed, dents, roll-off, etc. were all improved.

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

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

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

[Industrial availability]

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

Point A, B, C, D‧‧‧

h‧‧‧vertical line

j, k, m, t‧‧‧ line

Claims (10)

An abrasive composition for disk substrates, which includes: alumina particles; water-soluble polymer compounds; organic sulfate ester salt compounds; acids and/or salts thereof; and water, wherein the water-soluble polymer compound is a compound containing A mixture of a polymer containing a monomer with a carboxylic acid group as an essential monomer and a polymer containing a monomer with a sulfonic acid group as an essential monomer, and/or a mixture of a monomer with a carboxylic acid group and a polymer with a sulfonic acid group The monomer is a copolymer of essential monomers, and the organic sulfate ester salt compound is represented by the following general formula (1), and the pH value (25°C) ranges from 0.1 to 4.0 RO-SO ₃ M (1) in the formula , R represents a linear or branched alkyl, alkenyl, allyl or allyl group with a carbon number of 5 to 21, M represents an alkali metal, alkaline earth metal, ammonium ion or organic cation. An abrasive composition for disk substrates, which includes: alumina particles; water-soluble polymer compounds; organic sulfate ester salt compounds; acids and/or salts thereof; and water; wherein the water-soluble polymer compound is a compound containing A mixture of polymers containing monomers with carboxylic acid groups as essential monomers and polymers containing monomers with sulfonic acid groups as essential monomers, and/or mixtures of polymers containing monomers with carboxylic acid groups and monomers with sulfonic acid groups The monomer is a copolymer of essential monomers, and the organic sulfate ester salt compound is represented by the following general formula (2), and the pH value (25°C) ranges from 0.1 to 4.0 RO-(AO) _n -SO ₃ M ( 2) In the formula, R represents a linear or branched alkyl, alkenyl, allyl or allyl group with a carbon number of 5 to 21, AO represents an oxyalkylene group with a carbon number of 2 or 3, and 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 disk substrates described in the first or second patent scope, wherein the water-soluble polymer compound contains a monomer with a carboxylic acid group and a monomer with a sulfonic acid group as essential monomers The copolymer is a copolymer with monomers having carboxylic acid groups, monomers having sulfonic acid groups and monomers having amide groups as essential monomers. The abrasive composition for disk substrates as described in item 1 or 2 of the patent application, wherein the alumina particles contain α-alumina, and the average particle size is 0.1~2.0 μm, and in the composition The concentration is 1~50% by mass. The abrasive composition for disk substrates as described in item 1 or 2 of the patent application, wherein the monomer with a carboxylic acid group is selected from the group consisting of acrylic acid or its salts, methacrylic acid or its salts. . The abrasive composition for disk substrates as described in item 1 or 2 of the patent application, wherein the monosystem with a sulfonic acid group is selected from isoprene sulfonic acid, 2-acrylamide-2-methyl Propanesulfonic acid, 2-methacrylamide-2-methylpropanesulfonic acid, styrenesulfonic acid, ethylenesulfonic acid, propylenesulfonic acid, isopentenesulfonic acid, vinyl naphthalenesulfonic acid and one of their salts Or two or more monomers. The abrasive composition for disk substrates as described in item 3 of the patent application, wherein the monosystem with an amide group is selected from the group consisting of acrylamide, methacrylamide, N-alkyl acrylamide, N -Monomer of alkyl methacrylamide. The abrasive composition for magnetic disk substrates described in item 1 or 2 of the patent application, wherein the monomer with a carboxylic acid group is a polymer that is an essential monomer, and the monomer with a sulfonic acid group is Polymers of essential monomers, copolymers using the monomer with a carboxylic acid group and a monomer with a sulfonic acid group as essential monomers, and copolymers with the monomer having a carboxylic acid group and a monomer with a sulfonic acid group and The weight average molecular weight of the copolymer in which the monomer having a amide group is an essential monomer is 1,000 or more and 1,000,000 or less. The abrasive composition for magnetic disk substrates described in the first or second patent application, wherein the abrasive composition further contains an oxidizing agent. The abrasive composition for magnetic disk substrates described in item 1 or 2 of the patent application is used for polishing aluminum magnetic disk substrates electroless nickel-phosphorus electroplated.

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