JP2012140523A - Alkali detergent composition for glass substrate for hard disk - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an alkali detergent composition for a glass substrate for a hard disk having higher detergency, and to provide a method for producing a glass substrate for a hard disk by using the same.SOLUTION: The alkali detergent composition for a glass substrate for a hard disk includes: an alkali agent (component A); a chelating agent (component B); an amphoteric polymer compound (component C) containing a structural unit (c1) comprising at least one of an ammonium group and an amino group, and a structural unit (c2) comprising an anionic group; and water (component D), wherein: the content of the component A is 10-55 wt.%, the content of the component B is 5-60 wt.%, and the content of the component C is 5-60 wt.%, provided that the total content of components other than the component D is 100 wt.%; and the total content of the component A, component B and component C is 30-100 wt.%.

Description

  The present invention relates to an alkaline detergent composition for a glass substrate for hard disk and a method for producing a glass substrate for hard disk using the same.

  In order to increase the recording density, the glass hard disk drive is required to reduce the flying height of the magnetic head and reduce the unit recording area for the purpose of increasing the recording density. Accordingly, surface quality such as cleanliness required for a polished surface obtained by polishing an object to be polished is also increasing in the glass hard disk manufacturing process.

  By the way, the manufacturing process of the glass hard disk includes a polishing process using inorganic particles such as ceria and colloidal silica. If fine particles (inorganic particles) such as abrasive grains and polishing residue remain on the substrate surface that has undergone the polishing process, the performance and yield of the magnetic disk are adversely affected. In particular, even if fine particles are once peeled off from the substrate surface, they are likely to be reattached to the substrate surface. Therefore, the cleaning composition is required to have high dispersibility of inorganic particles. In order to prevent such redeposition of inorganic particles, a cleaning composition containing a dispersant such as a surfactant or a polymer compound has been disclosed (see Patent Documents 1 to 3).

  The cleaning agent described in Patent Document 1 includes polysaccharides and derivatives thereof, or poval (polyvinyl alcohol) and phosphate esters as dispersants. The detergent composition described in Patent Document 2 contains a cationic polymer as a dispersant. The cleaning composition described in Patent Document 3 contains a carboxylic acid copolymer or the like as a dispersant.

JP 2009-87523 A JP 2007-16110 A JP 2009-84509 A

  However, in recent years, along with the increase in capacity of glass hard disk drives, the level of cleanliness required for the substrate surface that has undergone the polishing process has become remarkably high, and the cleaning properties of the cleaning compositions described in Patent Documents 1 to 3 have been increased. However, it was found that the demand for high cleaning was insufficient. In particular, colloidal silica suitably used as abrasive grains has a high surface energy, so once it adheres to the substrate surface, it is difficult to peel off from the substrate surface, and even once peeled off, it tends to reattach to the substrate surface.

  Then, this invention provides the manufacturing method of the glass substrate for hard disks performed using the alkaline cleaning composition for glass substrates for hard disks with higher detergency.

The alkaline detergent composition for the glass substrate for hard disk of the present invention is:
An alkali agent (component A);
A chelating agent (component B);
An amphoteric polymer compound (component C) comprising a structural unit (c1) containing at least one of an ammonium group and an amino group and a structural unit (c2) containing an anionic group;
Water (component D),
When the total content of components other than the component D is 100% by weight,
The content of component A is 10 to 55% by weight,
The content of component B is 5 to 60% by weight,
The content of component C is 5 to 60% by weight,
And the total content of the said component A, the said component B, and the said component C is 30 to 100 weight%.

The method for producing a glass substrate for hard disk of the present invention comprises:
Polishing the substrate to be cleaned with a polishing composition containing inorganic fine particles and rinsing with water to obtain a substrate to be cleaned;
Cleaning the substrate to be cleaned using the alkaline cleaning composition for a glass substrate for hard disk of the present invention.

  ADVANTAGE OF THE INVENTION According to this invention, the alkaline cleaning composition for glass substrates for hard disks with higher detergency can be provided. Therefore, according to the method for producing a glass substrate for hard disk of the present invention using the alkaline detergent composition for glass substrate for hard disk of the present invention, a highly purified glass substrate for hard disk can be obtained.

  As a result of intensive studies, the present inventors have found that a cationic group and an anionic group are not used as a dispersant in water (component D), but in the surfactant and / or polymer compound conventionally used. A specific amphoteric polymer compound (component C) having both, and a predetermined amount of component A, component B, and component C, respectively, thereby providing a highly cleanable alkaline detergent composition for glass substrates for hard disks. It was found that a product (hereinafter sometimes abbreviated as “the cleaning composition of the present invention”) is obtained. In addition, when the structural unit (c1) of the amphoteric polymer compound (component C) contains an amino group, a hydrogen ion is coordinated to the amino group in water (component D), so that the amphoteric polymer compound (component) C) comes to have a cationic group. The structural unit (c2) of the amphoteric polymer compound (component C) has an anionic group by ionic dissociation in water (component D).

  The reason why the cleaning composition of the present invention has an excellent effect is considered as follows. In an alkaline solution, the silica particle surface and the substrate surface are generally negatively charged. However, with the electrification imparting force using only the alkali agent, the silica particles easily reattach to the substrate, and it is not easy to remove the reattached silica particles having a primary particle diameter of several nm from the substrate. Therefore, it is necessary to improve the dispersibility of the silica particles in the cleaning composition. In the present invention, a cationic group of an amphoteric polymer compound is adsorbed on the surface of a silica particle or a substrate, and charge repulsion due to the anionic group of the amphoteric polymer compound and steric hindrance of the amphoteric polymer compound are applied to the substrate. The reattachment of silica particles is effectively suppressed.

  Hereinafter, each component contained in the cleaning composition of the present invention will be described.

[Alkaline agent (component A)]
The alkaline agent (component A) contained in the cleaning composition of the present invention may be either an inorganic alkaline agent or an organic alkaline agent. Examples of the inorganic alkaline agent include ammonia, potassium hydroxide, and sodium hydroxide. Examples of the organic alkali agent include one or more selected from the group consisting of hydroxyalkylamine, tetramethylammonium hydroxide, and choline. These alkaline agents may be used alone or in combination of two or more.

  Examples of the hydroxyalkylamine include monoethanolamine, diethanolamine, triethanolamine, methylethanolamine, methyldiethanolamine, monopropanolamine, dipropanolamine, tripropanolamine, methylpropanolamine, methyldipropanolamine, aminoethylethanolamine. Etc.

  Among the alkaline agents, selected from the group consisting of potassium hydroxide, sodium hydroxide, monoethanolamine, methyldiethanolamine, and aminoethylethanolamine, from the viewpoint of improving the cleanability, and particularly from the viewpoint of facilitating etching control for glass. And at least one selected from the group consisting of potassium hydroxide and sodium hydroxide is more preferable.

  The content of the alkaline agent contained in the cleaning composition of the present invention is the sum of the contents of components other than water (component D), from the viewpoint of improving cleaning properties and ease of etching control for glass. Assuming 100% by weight, it is 10 to 55% by weight, preferably 15 to 50% by weight, and more preferably 20 to 50% by weight.

[Chelating agent (component B)]
The chelating agent (component B) contained in the cleaning composition of the present invention includes aldonic acids such as gluconic acid and glucoheptonic acid; aminocarboxylic acids such as ethylenediaminetetraacetic acid; hydroxycarboxylic acids such as citric acid and malic acid; And phosphonic acids such as methylenephosphonic acid and hydroxyethylidene diphosphonic acid; and alkali metal salts, lower amine salts, ammonium salts and alkanolamine salts thereof. Among the chelating agents, sodium gluconate, hydroxyethylidene diphosphonic acid, hydroxyethylidene diphosphonate sodium, or aminotrimethylene phosphonic acid ethylenediamine tetrasilane is used from the viewpoint of improving the cleaning property of the cleaning composition against dirt such as silica particles. Tetrasodium acetate is preferred. These chelating agents may be used alone or in admixture of two or more.

  The content of the chelating agent in the cleaning composition of the present invention is 100 in terms of the total content of components other than water (component D) from the viewpoint of improving the cleaning properties against dirt such as silica particles of the cleaning composition. In terms of weight%, it is 5 to 60% by weight, preferably 10 to 50% by weight, and more preferably 15 to 45% by weight.

[Amphoteric polymer compound (component C)]
The amphoteric polymer compound (component C) contained in the cleaning composition of the present invention is a structural unit (c1) containing at least one of an ammonium group and an amino group (hereinafter referred to as “structural unit (c1)”). ] And a structural unit (c2) having an anionic group [hereinafter referred to as “structural unit (c2)”. ]. The amphoteric polymer compound includes not only a polymer compound containing the structural unit (c1) and the structural unit (c2) but also a salt thereof. The amino group is preferably at least one of a tertiary amine group and a secondary amine group from the viewpoint of increasing the charge imparting power and improving the detergency.

  The structural unit (c1) is a monomer represented by the following general formula (1) and a single monomer represented by the following general formula (2) from the viewpoint of improving the cleaning properties and ease of etching control for glass. The structural unit derived from any one monomer selected from the body is preferable, and the structural unit represented by the following general formula (3) is more preferable.

In the general formulas (1) and (2), R ¹ , R ² , R ³ , R ⁷ , R ⁸ and R ⁹ are each independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. X, Y are each independently an alkylene group having 1 to 12 carbon ^{atoms, -COOR 12 -, - CONHR 12} -, - OCOR 12 -, - a group selected from - R ¹³ -OCO-R ^12. Here, R ¹² and R ¹³ are each independently an alkylene group having 1 to 5 carbon atoms. R ⁴ is an alkyl group having 1 to 3 carbon atoms, a hydroxyalkyl group having 1 to 3 carbon atoms, or R ¹ R ² C═C (R ³ ) —X—. R ⁵ is an alkyl group having 1 to 3 carbon atoms, or a hydroxyalkyl group having 1 to 3 carbon atoms, and R ⁶ is an alkyl group having 1 to 3 carbon atoms, a hydroxyalkyl group having 1 to 3 carbon atoms, or a benzyl group. And Z ⁻ represents an anion. R ¹⁰ is a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, a hydroxyalkyl group having 1 to 3 carbon atoms, or R ⁷ R ⁸ C═C (R ⁹ ) —Y—. R ¹¹ is a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or a hydroxyalkyl group having 1 to 3 carbon atoms.

  Among the structural units (c1), from the viewpoint of improving detergency, a structural unit containing an ammonium group is preferred, a structural unit containing a quaternary ammonium group is more preferred, and a structural unit represented by the following general formula (3) Further preferred.

In General Formula (3), R ^1b is an alkyl group having 1 to 3 carbon atoms or a hydroxyalkyl group having 1 to 3 carbon atoms, m and n are each a number of 0 or 1, and m + n = 1. . When m = 1 and n = 0, the structural unit (c1) includes a five-membered ring, and when m = 0 and n = 1, the structural unit (c1) includes a six-membered ring. When all of the structural unit (c1) of the amphoteric polymer compound (component C) is the structural unit represented by the general formula (3), the amphoteric polymer compound is structural unit (c1) from the viewpoint of improving detergency. ) Are all preferably the structural unit (c1) containing the five-membered ring, or the structural unit (c1) containing the six-membered ring. Z ⁻ represents an anion.

In general formula (3), R ^1b is preferably a methyl group from the viewpoint of improving detergency, and Z ⁻ is a halide ion, sulfate ion, phosphate ion, fatty acid ion having 1 to 12 carbon atoms, or 1 to 3 carbon atoms. A benzenesulfonate ion that may be substituted by 1 to 3 alkyl groups is preferred, and a chloride ion is more preferred. n is preferably 0.

  As the structural unit (c2), a structural unit represented by the following general formula (4) is preferable from the viewpoint of improving the detergency.

In General Formula (4), R ^2b is a hydrogen atom, a methyl group, or —COOM, and R ^3b is a hydrogen atom, a methyl group, or a hydroxy group. A is -COOM, or -ph-SO ₃ M. Here, M is a hydrogen atom, an alkali metal or an alkaline earth metal, and ph represents a phenylene group.

  The amphoteric polymer compound (component C) contained in the cleaning composition of the present invention can be produced by polymerizing a monomer corresponding to the constituent unit of component C by an ordinary polymerization reaction. Alternatively, an ionic group is introduced into a polymer compound obtained by polymerization of a monomer different from the monomer corresponding to the constituent unit of component C and ionization treatment is performed, and finally the amphoteric polymer compound (component C ) May be manufactured. For example, in addition to a method of obtaining a component C by polymerizing a monomer having a cationic group and a monomer having an anionic group, a monomer having no cationic group and an anion A component C having both the anionic group and the cationic group may be finally obtained by cationizing a polymer compound obtained by polymerization with a monomer having a cationic group. Specifically, when the amphoteric polymer compound (component C) contains a quaternary ammonium group as a cationic group, a monomer having a quaternary ammonium group and an anionic group in the monomer In addition to the method of obtaining a component C by polymerizing the product, the polymer compound obtained by polymerizing a monomer having an amino group and a monomer having an anionic group is subjected to quaternization treatment. To obtain component C. In addition, the anionic group is finally obtained by anionizing a polymer compound obtained by polymerization of a monomer having no anionic group and a monomer having a cationic group. And component C having both cationic groups. The “monomer corresponding to the constituent unit of component C” means a monomer that can be a constituent unit of component C without being ionized. The “monomer having an anionic group” means a monomer having an anionic group by ion dissociation in water.

  As a monomer represented by the general formula (1), acryloyl (or methacryloyl) aminoalkyl (C1-5) -N, N, N-trialkyl (C1-3) quaternary ammonium salt, Acryloyl (or methacryloyl) oxyalkyl (1 to 5 carbon atoms) -N, N, N-trialkyl (1 to 3 carbon atoms) quaternary ammonium salt, N- (ω-alkenyl (2 to 10 carbon atoms))- N, N, N-trialkyl (C1-C3) quaternary ammonium salt, N, N-di (ω-alkenyl (C2-C10))-N, N-dialkyl (C1-C3) A quaternary ammonium salt etc. are mentioned, The structural unit of General formula (3) originating in these comprises a part of amphoteric polymer compound (component C).

  In addition, examples of the monomer represented by the general formula (2) include acryloyl (or methacryloyl) aminoalkyl (1 to 5 carbon atoms) -N, N-dialkyl (1 to 3 carbon atoms) amine, acryloyl (or methacryloyl). ) Oxyalkyl (C1-5) -N, N-dialkyl (C1-3) amine, N- (ω-alkenyl (C2-10))-N, N-dialkyl (C1 3) Amine, N, N-di (ω-alkenyl (2 to 10 carbon atoms))-N-alkyl (1 to 3 carbon atoms) amine, allylamine, diallylmethylamine, diallylamine and the like.

  Monomer represented by general formula (2) in a polymer compound obtained by polymerizing a monomer represented by general formula (2) and a monomer that is a supply source of structural unit (c2) Component C can also be produced by alkylating the structural unit (c1) derived from 1 with a quaternizing agent such as methyl chloride, dimethyl sulfate, diethyl sulfate, ethylene oxide, propylene oxide or the like. When ethylene oxide and / or propylene oxide is used as the quaternizing agent, the amino group is neutralized with an acid represented by ZH (Z is a group corresponding to the anion Z-).

  The monomer that is the source of the structural unit represented by the general formula (4) includes acrylic acid or a salt thereof, methacrylic acid or a salt thereof, crotonic acid or a salt thereof, α-hydroxyacrylic acid or a salt thereof, maleic Examples thereof include acids or salts thereof, maleic anhydride, and styrene sulfonate. In addition, the structural unit derived from styrene sulfonate is neutralized after sulfonating a polymer compound containing the structural unit derived from styrene using a sulfonating agent such as sulfur trioxide, chlorosulfonic acid, sulfuric acid or the like. You can also get it.

  The amphoteric polymer compound preferably includes a structural unit having a quaternary ammonium group as the structural unit (c1) from the viewpoint of improving detergency, but as a structural unit having a quaternary ammonium group, from the same viewpoint, A constitutional unit derived from an N, N-diallyl-N, N-dialkyl (C1-C3) quaternary ammonium salt, or a constitution derived from an N, N-diallyl-N-alkyl (C1-C3) amine A structural unit obtained by alkylating a unit with a quaternizing agent such as methyl chloride, dimethyl sulfate, diethyl sulfate, ethylene oxide, propylene oxide or the like is preferable. From the same viewpoint, the structural unit having an anionic group is derived from at least one monomer selected from acrylic acid or a salt thereof, methacrylic acid or a salt thereof, maleic acid or a salt thereof, and maleic anhydride. These structural units are preferred. Examples of N, N-diallyl-N, N-dialkyl (C1-3) quaternary ammonium salts include diallyldimethylammonium chloride, diallyldihydroxymethylammonium chloride, diallyldiethylammonium chloride, diallyldihydroxyethylammonium chloride, diallyl. Examples thereof include dimethylammonium hydrochloride, diallyldiethylammonium sulfate, and dimethylaminoethyl methacrylate chloride. Examples of the N, N-diallyl-N-alkyl (C1-3) amine include diallylmethylamine, diallylhydroxymethylamine, diallylethylamine, diallylhydroxyethylamine, and the like.

  In the amphoteric polymer compound (component C) contained in the cleaning composition of the present invention, from the viewpoint of improving the cleaning properties, [total number of moles of ammonium group and amine group] / [total number of moles of anionic group] The molar ratio is preferably 30/70 to 95/5, more preferably 40/60 to 70/25, and still more preferably 50/50 to 70/25. From the same viewpoint, the total number of moles of ammonium groups and amine groups contained in one structural unit (c1) is equal to the total number of moles of anionic groups contained in one structural unit (c2). The molar ratio (c1 / c2) between the structural unit (c1) and the structural unit (c2) is preferably 30/70 to 95/5, more preferably 40/60 to 70/25, and 50/50 to 70/25 is more preferable.

  In the amphoteric polymer compound (component C) contained in the cleaning composition of the present invention, the total molar percentage of the structural unit (c1) and the structural unit (c2), preferably from the general formula ( The total mole percentage of the structural unit represented by 3) and the structural unit represented by the general formula (4) is preferably 50 to 100 mol%, assuming that all the structural units constituting Component C are 100 mol%. 70-100 mol% is more preferable, 80-100 mol% is further more preferable, and 90-100 mol% is still more preferable. Moreover, in the component C contained in the cleaning composition of the present invention, from the viewpoint of improving the cleaning property, the total mole percentage of the structural unit (c1) containing at least one of an ammonium group and an amine group (preferably, The mole percentage of the structural unit (c1) when all of the structural units (c1) are quaternary ammonium groups) is preferably 30 to 90 mol%, assuming that all the structural units constituting the component C are 100 mol%. 40-80 mol% is more preferable, and 50-70 mol% is further more preferable.

  In the present invention, in addition to the structural unit (c1) and the structural unit (c2), preferably the structural unit represented by the general formula (3) and the structural unit represented by the general formula (4) The structural unit (c3) may be included so as not to impair the effect. The monomers that are the supply sources of the structural unit (c1), the structural unit (c2), and the structural unit (c3) are copolymerizable with each other.

  Examples of the monomer that is a supply source of the structural unit (c3) include acrylamide, N, N-dimethylaminopropylacrylic acid (or methacrylic acid) amide, N, N-dimethylacrylic (or methacrylic) amide, N, N- Dimethylaminoethyl acrylic acid (or methacrylic acid) amide, N, N-dimethylaminoethyl acrylic acid (or methacrylic acid) amide, N-vinyl-2-caprolactam, N-vinyl-2-pyrrolidone, acrylic acid (or methacrylic acid) ) Alkyl (1-5 carbon atoms), acrylic acid (or methacrylic acid) 2-hydroxyethyl, acrylic acid (or methacrylic acid) -N, N-dimethylaminoalkyl (1-5 carbon atoms), vinyl acetate, ethylene, Propylene, N-butylene, isobutylene, N-pentene, isoprene, 2-methyl-1-butyl N-hexene, 2-methyl-1-pentene, 3-methyl-1-pentene, 4-methyl-1-pentene, 2-ethyl-1-butene, styrene, vinyltoluene, α-methylstyrene, ethylene oxide, Examples include propylene oxide, 2-vinylpyridine, 4-vinylpyridine, sulfur dioxide and the like.

  The amphoteric polymer compound (component C) contained in the cleaning composition of the present invention is a copolymer containing the structural unit (c1), the structural unit (c2), and the structural unit (c3) from the viewpoint of improving detergency. And / or a salt thereof, and assuming that the total structural unit constituting the amphoteric polymer compound (component C) is 100 mol%, the total molar percentage of the structural unit (c3) derived from sulfur dioxide is 1 to 15 mol. % Is preferable. The structural unit (c3) derived from sulfur dioxide is represented by the following formula (5).

Component C may be obtained by any polymerization method, but a radical polymerization method is particularly preferred, and this can be done in a bulk, solution, or emulsion system. The radical polymerization may be started by heating, but as an initiator, 2,2′-azobis (2-amidinopropane) dihydrochloride, 2,2′-azobis (N, N-dimethyleneisobutylamidine) ) Azo initiators such as dihydrochloride; hydrogen peroxide, benzoyl peroxide, t-butyl hydroperoxide, cumene hydroperoxide, methyl ethyl ketone peroxide, and organic peroxides such as perbenzoic acid, sodium persulfate, Persulfates such as potassium persulfate and ammonium persulfate, redox initiators such as hydrogen peroxide and Fe ³⁺ ; existing radical initiators and the like may be used. Alternatively, the polymerization may be initiated by light irradiation in the presence / absence of a photosensitizer or irradiation.

  The weight average molecular weight of Component C is preferably 1,000 to 6,000,000, more preferably 5,000 to 3,000,000, and still more preferably 10,000 to 2,000,000. Specifically, the weight average molecular weight is measured by the measurement method described in Examples.

  The content of the amphoteric polymer compound (component C) in the cleaning composition of the present invention is 5 when the total content of components other than water (component D) is 100% by weight from the viewpoint of improving cleaning properties. -60% by weight, preferably 5-50% by weight, more preferably 9-40% by weight.

[Water (component D)]
The water (component D) contained in the cleaning composition of the present invention is not particularly limited as long as it can serve as a solvent. For example, ultrapure water, pure water, ion exchange water, or distillation Although water etc. can be mentioned, an ultrapure water, a pure water, or ion-exchange water is preferable, and an ultrapure water is more preferable. Pure water and ultrapure water can be obtained, for example, by passing tap water through activated carbon, subjecting it to ion exchange treatment, and further distilling it, irradiating it with a predetermined ultraviolet germicidal lamp or passing it through a filter as necessary. Can do. For example, the electrical conductivity at 25 ° C. is often 1 μS / cm or less for pure water and 0.1 μS / cm or less for ultrapure water. The cleaning composition of the present invention may further contain a water-soluble organic solvent (for example, alcohol such as ethanol) in addition to the water as a solvent, but is included in the cleaning composition of the present invention. The solvent is preferably made of water only.

[Optional ingredients]
In addition to the components A to D, the cleaning composition of the present invention may contain nonionic surfactants, solubilizers, antioxidants, preservatives, and the like.

[Nonionic surfactant (component E)]
The cleaning composition of the present invention may contain a nonionic surfactant (component E) from the viewpoint of improving the cleaning properties of the cleaning composition. As the nonionic surfactant (component E) contained in the cleaning composition of the present invention, for example, a nonionic surfactant represented by the following general formula (6) is used as the cleaning composition. It is preferable from the viewpoint of improvement of detergency.
R ¹⁴ —O— (EO) _o (PO) _p —H (6)

In the general formula (5), R ¹⁴ is preferably a linear or branched alkyl group having 8 to ¹⁴ carbon atoms, EO is an ethyleneoxy group, and PO is an oxypropylene group. o and p are the average added moles of EO and PO, respectively. o is preferably a number of 5 to 20, and p is preferably a number of 0 to 4.

  Specific examples of the compound represented by the general formula (6) include alcohols such as decanol, isodecyl alcohol, tridecyl alcohol, lauryl alcohol, myristyl alcohol, stearyl alcohol, oleyl alcohol, octylphenol, nonylphenol, dodecylphenol, and the like. Examples thereof include compounds in which an oxyethylene group and / or an oxypropylene group are added to the above phenols. The compound represented by the general formula (6) may be used alone or in combination of two or more.

  The content of the nonionic surfactant (component E) in the cleaning composition of the present invention is the content of components other than water (component D) from the viewpoint of improving the cleaning performance of the cleaning composition against organic soil. When the total content is 100% by weight, 1 to 30% by weight is preferable, 1 to 20% by weight is more preferable, and 1 to 15% by weight is even more preferable.

[Solubilizer (Component F)]
The cleaning composition of the present invention is selected from the group consisting of p-toluenesulfonic acid, dimethylbenzenesulfonic acid, 2-ethylhexanoic acid, and salts thereof from the viewpoint of improving the storage stability of the cleaning composition. One or more solubilizers (component F) may be included. The solubilizer improves the dispersibility in a detergent composition such as a nonionic surfactant (component E).

  The content of component F in the cleaning composition of the present invention is 1 when the total content of components other than water (component D) is 100% by weight from the viewpoint of improving the storage stability of the cleaning composition. -60% by weight is preferred, 3-50% by weight is more preferred, 5-50% by weight is more preferred, and 10-50% by weight is even more preferred.

  The cleaning composition of the present invention is used after being diluted, for example. The dilution rate is preferably 20 to 500 times in consideration of cleaning efficiency. The water for dilution may be the same as component D described above. When the cleaning composition of the present invention is used after being diluted, the content of each component contained in the cleaning composition before dilution is from 5 to 12% by weight from the viewpoint of improving cleaning properties. %, The chelating agent (component B) is preferably 2 to 10% by weight, the amphoteric polymer compound (component C) is preferably 0.5 to 10% by weight, and the water (component D) is 68 to 92.5% by weight. % Is preferred.

  The content of each component contained in the diluted cleaning composition is, for example, preferably from 0.009 to 0.7% by weight, preferably 0.01 to 0% by weight from the viewpoint of improving cleaning properties. 0.5 wt% is more preferable, 0.04 to 0.4 wt% is more preferable, and the chelating agent (component B) is preferably 0.003 to 0.6 wt%, and 0.01 to 0.5 wt% More preferably, 0.01 to 0.3% by weight is more preferable, and the amphoteric polymer compound (component C) is preferably 0.001 to 0.5% by weight, more preferably 0.002 to 0.4% by weight, 0.005 to 0.3% by weight is more preferable, and water (component D) is preferably 97 to 99.98% by weight, more preferably 98 to 99.98% by weight, and further 99 to 99.98% by weight. preferable. In addition, the cleaning composition having the diluted composition described above may be prepared and used as it is so as not to be diluted.

  The weight ratio (component C (% by weight) / component B (% by weight)) of the amphoteric polymer compound (component C) and the chelating agent (component B) contained in the cleaning composition of the present invention is a viewpoint of improving cleaning properties. 1 / 0.1 to 1/5 is preferable, 1 / 0.5 to 1/5 is more preferable, and 1 / 0.5 to 1 / 4.5 is more preferable.

  The total content of the component A, the component B, and the component C in the cleaning composition of the present invention is improved when the total content of components other than water (component D) is 100% by weight. However, from the same viewpoint, it is preferably 40 to 100% by weight, and more preferably 50 to 100% by weight.

[pH]
The pH at 25 ° C. of the cleaning composition of the present invention is not particularly limited as long as the glass surface is not damaged, but is preferably 11 to 14, more preferably 12 or more, from the viewpoint of improving cleaning properties. 13 is more preferable. The pH can be measured using a pH meter (HM-30G, manufactured by Toa Denpa Kogyo Co., Ltd.), and is a value 40 minutes after immersion of the electrode in the cleaning composition.

[Method of manufacturing glass substrate for hard disk]
In the method for producing a glass substrate for hard disk of the present invention, for example, a substrate to be cleaned having a glass surface and subjected to polishing using a polishing composition on the glass surface is used with the cleaning composition of the present invention. Cleaning step. In the polishing, for example, a rough polishing process and a final polishing process are performed in this order. The inorganic fine particles contained in the abrasive composition used in the rough polishing treatment are preferably cerium oxide particles because they can be polished at high speed. Silica particles are preferable because the inorganic fine particles contained in the abrasive composition used in the final polishing treatment improve surface flatness (low roughness).

  In one example of the method for producing a glass substrate for hard disk of the present invention, after rough polishing, cleaning (first cleaning), rinsing (first rinsing), and drying using the cleaning composition of the present invention. (First drying treatment), finish polishing treatment, washing treatment using the cleaning composition of the present invention (second washing treatment), rinsing treatment (second rinsing treatment), and drying treatment (second drying treatment). Done in order.

  A hard disk is obtained by forming a magnetic layer having a magnetic recording region and including a metal thin film on the glass substrate for hard disk by a method such as sputtering. Examples of the metal material constituting the metal thin film include a cobalt alloy that is an alloy of chromium, tantalum, platinum, or the like and cobalt. In addition, a magnetic layer may be formed in the both main surface side of the glass substrate for hard disks, and may be formed only in one main surface side.

[How to clean the glass substrate surface for hard disks]
In the method for cleaning a glass substrate for a hard disk of the present invention (hereinafter sometimes abbreviated as “cleaning method of the present invention”), for example, polishing using a polishing composition on a glass surface having the glass surface. The cleaning process which wash | cleans the to-be-cleaned board | substrate which was given using the cleaning composition of this invention is included. In the cleaning step, for example, (a) the substrate to be cleaned is immersed in the cleaning composition, and / or (b) the cleaning composition is injected and the cleaning composition is formed on the surface of the substrate to be cleaned. Is supplied.

  In the method (a), the conditions for immersing the substrate to be cleaned in the cleaning composition are not particularly limited. For example, the temperature of the cleaning composition may be the cleaning property, safety, and operation of the cleaning composition. From the viewpoint of safety, the temperature is preferably 20 to 100 ° C., and the immersion time is preferably 10 seconds to 30 minutes from the viewpoint of the cleaning performance and production efficiency of the cleaning composition. Further, from the viewpoint of improving detergency, it is preferable that ultrasonic vibration is applied to the cleaning composition. The frequency of the ultrasonic wave is preferably 20 to 2000 kHz, more preferably 30 to 2000 kHz, and further preferably 30 to 1500 kHz.

  In the method (b), from the viewpoint of promoting the cleaning properties of the inorganic particles and the solubility of the oil, the cleaning agent composition to which ultrasonic vibration is applied is injected to the surface of the substrate to be cleaned. The surface is contacted to clean the surface, or the cleaning composition is supplied by injection onto the surface of the substrate to be cleaned and then cleaned by rubbing the surface supplied with the cleaning composition with a cleaning brush. It is preferable to do. Furthermore, the cleaning composition to which ultrasonic vibration is applied is supplied to the surface to be cleaned by injection, and the surface to which the cleaning composition is supplied is cleaned by rubbing with a cleaning brush. Is preferred.

  As means for supplying the cleaning composition onto the surface of the substrate to be cleaned, known means such as a spray nozzle can be used. Moreover, there is no restriction | limiting in particular as a brush for washing | cleaning, For example, well-known things, such as a nylon brush and a PVA (polyvinyl alcohol) sponge brush, can be used. The ultrasonic frequency may be the same as the value preferably adopted in the method (a).

  In addition to the method (a) and / or the method (b), the cleaning method of the present invention includes one step using known cleaning such as rocking cleaning, cleaning using rotation of a spinner, paddle cleaning and the like. The above may be included.

  The substrate to be cleaned to which the cleaning method of the present invention is suitably applied is, for example, a glass substrate made of borosilicate glass substrate, aluminosilicate glass or crystallized glass, aluminosilicate glass or crystallized glass.

  In the glass surface cleaning method of the present invention, the substrates to be cleaned may be cleaned one by one, or a plurality of substrates to be cleaned may be cleaned at once. The number of cleaning tanks used for cleaning may be one or more.

[Preparation of cleaning composition]
Each component was blended by weight% so as to have the composition described in Table 1 and Table 2, and mixed to obtain cleaning compositions of Examples and Comparative Examples. A commercially available aqueous solution (concentration: 48% by weight) was used for KOH and NaOH in the table. The weight average molecular weights of the amphoteric polymer compounds 1 to 3 were measured as follows.

(Method for measuring weight average molecular weight of amphoteric polymer compound)
The weight average molecular weights of the amphoteric polymer compounds 1 to 3 were measured by a gel permeation chromatography (GPC) method under the following measurement conditions.
[GPC conditions]
Column: TSKgel G4000PWXL + TSKgel G2500PWXL (manufactured by Tosoh Corporation)
Guard column: TSKguardcolumn PWXL (manufactured by Tosoh Corporation)
Eluent: 0.2M phosphate buffer / CH ₃ CN = 9/1 (volume ratio)
Temperature: 40 ° C
Flow rate: 1.0 mL / min
Sample size: 5 mg / mL
Detector: RI
Conversion standard: Polyethylene glycol

[Cleaning test method for glass substrates for hard disks]
By performing polishing using a polishing slurry (abrasive composition) having the following composition, a substrate to be cleaned contaminated with abrasive particles derived from the polishing slurry and polishing scraps derived from the substrate material was prepared. The cleaning property of the cleaning composition was evaluated using the substrate to be cleaned.

(Evaluation board)
As an evaluation substrate, an aluminosilicate glass substrate (outer diameter: 65 mmφ, inner diameter: 20 mmφ, thickness: 0.635 mm) was prepared.

(Polishing conditions)
Polishing machine: Double-sided 9B polishing machine (manufactured by Hamai Sangyo Co., Ltd.)
Polishing pad: Suede pad polishing agent for finish polishing manufactured by FILWEL Co., Ltd .: Colloidal silica slurry (number average particle size of colloidal silica particles 24 nm, concentration of colloidal silica particles: 8% by weight, medium: water; manufactured by Kao Corporation)
Pre-polishing: Load 40g / cm ² , time 60 seconds, polishing fluid flow rate 100mL / min
Main polishing: Load 100g / cm ² , time 1200 seconds, polishing fluid flow 100mL / min
Water rinse: load 40g / cm ² , time 60 seconds, rinse water flow rate 2L / min

(Washing)
The contaminated substrates to be cleaned (5 sheets) were cleaned with a cleaning apparatus under the following conditions. Two sets of washing tank and rinsing tank were prepared.
(1) Cleaning-1: A cleaning tank (1500 l) containing 450 g of the cleaning composition is set at 40 ° C., the substrate to be cleaned is immersed, and cleaning is performed for 120 seconds while irradiating ultrasonic waves (40 kHz).
(2) Rinsing-1: The substrate to be cleaned is transferred to a rinsing tank (40 ° C.) containing ultrapure water, and rinsing is performed for 120 seconds while irradiating ultrasonic waves (40 kHz).
(3) Repeat (1) and (2) again using a washing tank containing an unused detergent composition and a rinsing tank containing unused ultrapure water.
(4) Cleaning-2: The substrate to be cleaned is transferred from the rinsing tank to a scrub cleaning unit (A) on which a cleaning brush is set, and a cleaning composition at room temperature (25 ° C.) is injected onto the cleaning brush. Cleaning is performed at 25 ° C. for 5 seconds by pressing the cleaning brush against both surfaces of the substrate while rotating at 400 rpm in the presence of the agent composition. The cleaning composition having the same composition as the cleaning composition used in “(1) Cleaning-1” is used.
(5) Rinsing-2: Transfer the substrate to be cleaned to an unused scrub cleaning unit (B), inject ultra-pure water at 25 ° C., and rinse the cleaning brush on both sides of the substrate in the same manner as in (4). Perform for 5 seconds.
(6) Repeat (4) and (5) again.
(7) Rinsing-3: The substrate to be cleaned is transferred to a resin tank containing ultrapure water and rinsed at 25 ° C. for 600 seconds.
(8) Drying: The substrate to be cleaned is transferred to a resin tank containing warm pure water and immersed for 60 seconds, and then the substrate to be cleaned is pulled up at a rate of 250 mm / min, and then the substrate surface is completely dried.

(Cleanability evaluation)
A cleaned substrate rotating at 10000 rpm is irradiated with a laser using MODE Q-Scatter of an optical fine defect inspection apparatus (Candela 6100, manufactured by KLA Tencor) to measure the number of defects (the number of foreign matter on the substrate). Carried out. For each of the cleaning compositions of each example and comparative example, the measurement was performed on 10 substrates each, and the average was taken. The cleaning property was evaluated as a relative value when the number of defects in Comparative Example 2 was 100. The results are shown in Tables 1 and 2.

  As shown in Table 1 and Table 2, when the cleaning compositions of Examples 1 to 7 are used, the number of defects is smaller than when the cleaning compositions of Comparative Examples 1 to 6 are used. It can be seen that the cleaning compositions of Examples 1 to 7 each containing a predetermined amount of each of Component A to Component D have higher cleaning properties than the cleaning compositions of Comparative Examples 1 to 6.

The detail of each component in Table 1 and Table 2 is as follows.
(1) Hydroxyethylidene diphosphonic acid: Dequest 2010, manufactured by Solusia Japan
(2) Amphoteric polymer compound 1: copolymer of diallyldimethylammonium chloride, maleic acid and sulfur dioxide [diallyldimethylammonium chloride / maleic acid / sulfur dioxide = 66.7 / 26.7 / 6.6 (molar ratio) , Weight average molecular weight 20,000]
(3) Amphoteric polymer compound 2: copolymer of diallyldimethylammonium chloride and maleic acid [diallyldimethylammonium chloride / maleic acid = 50/50 (molar ratio), weight average molecular weight 13,000]
(4) Amphoteric polymer compound 3: Copolymer of dimethylaminoethyl methacrylate chloride and acrylic acid [dimethylaminoethyl methacrylate chloride / acrylic acid = 50/50 (molar ratio), weight average molecular weight 450,000]
(5) Water-soluble polymer: copolymer sodium salt of acrylic acid and 2-acrylamido-2-methylpropanesulfonic acid, [manufactured by Toagosei Co., Ltd., trade name: Aron A-6017, weight average molecular weight: 6000, AA / AMPS (Weight ratio 80:20, molar ratio: 90: 10%)
(6) Nonionic surfactant: polyoxyethylene polyoxypropylene alkyl ether (alkyl: 12 to 14 (carbon number of R ¹⁴ )) EO average added mole number o: 10 PO average added mole number p: 1. 5 Weight average molecular weight 700 (manufactured by Kao Corporation))
(7) Solubilizer: p-toluenesulfonic acid Na (manufactured by Kao Corporation)

  By using the cleaning composition of the present invention, it is possible to obtain a highly purified glass surface for a glass substrate for hard disk. Therefore, the present invention can contribute to an improvement in product yield.

Claims (6)

An alkali agent (component A);
A chelating agent (component B);
An amphoteric polymer compound (component C) comprising a structural unit (c1) containing at least one of an ammonium group and an amino group and a structural unit (c2) containing an anionic group;
Water (component D),
When the total content of components other than the component D is 100% by weight,
The content of component A is 10 to 55% by weight,
The content of component B is 5 to 60% by weight,
The content of component C is 5 to 60% by weight,
And the alkali cleaning composition for the glass substrate for hard disks whose sum total content of the said component A, the said component B, and the said component C is 30-100 weight%.   The alkaline detergent composition for glass substrates for hard disks according to claim 1, wherein the pH is 12 or more.   The alkaline cleaner for glass substrates for hard disks according to claim 1 or 2, wherein the molar ratio (c1 / c2) between the structural unit (c1) and the structural unit (c2) is 30/70 to 95/5. Composition.   The alkaline cleaning composition for glass substrates for hard disks according to any one of claims 1 to 3, further comprising a nonionic surfactant (component E).   5. The composition according to claim 1, further comprising one or more solubilizers (component F) selected from the group consisting of p-toluenesulfonic acid, dimethylbenzenesulfonic acid, 2-ethylhexanoic acid, and salts thereof. Item 4. An alkaline detergent composition for a glass substrate for hard disk according to the item. Polishing the substrate to be cleaned with a polishing composition containing inorganic fine particles and rinsing with water to obtain a substrate to be cleaned;
A step of cleaning the substrate to be cleaned using the alkaline cleaner composition for a glass substrate for hard disk according to any one of claims 1 to 5, and a method for producing a glass substrate for hard disk.