Cleaning liquid and cleaning method

Abstract

The present invention employs a cleaning liquid containing a solvent and a metal remover. The cleaning liquid contains two or more kinds of solvents, a distance (HSP distance) between a Hansen solubility parameter of the cleaning liquid and a Hansen solubility parameter of dimethylacetamide is 1.0 or less, and a content of a metal impurity is 0.1 × 10-9 parts by mass or greater and 102 × 10-6 parts by mass or less with respect to 100 parts by mass of a total amount of the solvents and the metal remover. According to such a cleaning liquid, removability of impurity stains is enhanced.

Description

TECHNICAL FIELD

[0001] The present invention relates to a cleaning liquid and a cleaning method.

[0002] Priority is claimed on Japanese Patent Application No. 2023-187033, filed October 31, 2023, the content of which is incorporated herein by reference.BACKGROUND ART

[0003] A cleaning liquid is required to be selected according to the type of stain and the material of a cleaning target.

[0004] In the industrial field, for example, in a film to be produced from a high-molecular-weight material, particularly a porous film, the influence of organic impurity stains such as high-molecular-weight residues derived from the high-molecular-weight material or metal impurity stains derived from a metal catalyst and the like used in a film production step is a problem.

[0005] In dealing with this problem, a film cleaning liquid in which a specific solvent is selected according to the material of the film has been proposed (see Patent Document 1).Citation ListPatent Document

[0006] Patent Document 1: Japanese Unexamined Patent Application, First Publication No. 2017-202479SUMMARY OF INVENTIONTechnical Problem

[0007] In the related art, in a filter to be produced from a porous film, a chemical liquid purified by the filter may be contaminated unintentionally. The contamination source is a high-molecular-weight or low-molecular-weight organic impurity or a metal impurity, which coexists in the filter. These impurities are not only derived from a high-molecular-weight material or a metal catalyst, but are also easily mixed from various places such as each pipe in a production line, a container to be used, and an instrument. On the other hand, with the miniaturization and high performance of industrial products, there is a strong demand for further reduction of the impurity stains as described above.

[0008] The present invention has been made in consideration of the above-described circumstances, and an object thereof is to provide a cleaning liquid having improved removability of impurity stains, and a cleaning method using the cleaning liquid. Solution to Problem

[0009] In order to solve the above-described problems, the present invention employs the following configurations.

[0010] According to a first aspect of the present invention, there is provided a cleaning liquid containing: a solvent and a metal remover, in which the cleaning liquid contains two or more kinds of solvents, a distance (HSP distance) between a Hansen solubility parameter of the cleaning liquid and a Hansen solubility parameter of dimethylacetamide is 1.0 or less, and a content of a metal impurity is 0.1 × 10 -9< parts by mass or greater and 10 2< × 10 -6< parts by mass or less with respect to 100 parts by mass of a total amount of the solvents and the metal remover.

[0011] According to a second aspect of the present invention, there is provided a cleaning method including cleaning a cleaning target by bringing the cleaning liquid according to the first aspect into contact with the cleaning target.Advantageous Effects of Invention

[0012] According to the present invention, it is possible to provide a cleaning liquid having improved removability of impurity stains, and a cleaning method using the cleaning liquid.

[0013] Such a cleaning liquid and a cleaning method using the cleaning liquid are useful for removing impurity stains from various cleaning targets.DESCRIPTION OF EMBODIMENTS(First aspect: cleaning liquid)

[0014] According to an embodiment, a cleaning liquid contains two or more kinds of solvents and a metal remover.

[0015] In the present embodiment, a distance (HSP distance) between a Hansen solubility parameter of the cleaning liquid and a Hansen solubility parameter of dimethylacetamide is 1.0 or less.

[0016] In addition, a content of a metal impurity in the cleaning liquid of the present embodiment is 0.1 × 10 -9< parts by mass or greater and 10 2< × 10 -6< parts by mass or less with respect to 100 parts by mass of a total amount of the solvents and the metal remover.<Solvent>

[0017] The cleaning liquid of the present embodiment contains two or more kinds of solvents.

[0018] The solvents contained in the cleaning liquid of the present embodiment can be appropriately selected from known organic solvents such that the HSP distance is 1.0 or less. Examples of the organic solvents include polar solvents such as a ketone-based solvent, an ester-based solvent, an alcohol-based solvent, a nitrile-based solvent, an amide-based solvent, an ether-based solvent, a sulfoxide-based solvent, and a sulfone-based solvent, and non-polar solvents such as a hydrocarbon-based solvent.

[0019] Among the organic solvents, organic solvents containing a plurality of kinds of functional groups that characterize each of the above-described solvents in the structure thereof are also present, but in this case, the organic solvent is considered to correspond to any solvent species containing the functional group of the organic solvent, as described below. For example, diethylene glycol monomethyl ether is considered to correspond to both the alcohol-based solvent and the ether-based solvent in the above-described classification.<<Ketone-based solvent>>

[0020] The ketone-based solvent is an organic solvent containing C-C(=O)-C in the structure thereof.

[0021] Specific examples of the ketone-based solvent include 1-octanone, 2-octanone, 1-nonanone, 2-nonanone, acetone, 4-heptanone, 1-hexanone, 2-hexanone, diisobutyl ketone, phenylacetone, methyl ethyl ketone, methyl isobutyl ketone, ionone, diacetonyl alcohol, acetyl carbinol, acetophenone, methyl naphthyl ketone, and methyl amyl ketone (2-heptanone).

[0022] In addition, the ketone-based solvent may be a cyclic ketone-based solvent. Specific examples of the cyclic ketone-based solvent include cyclohexanone (CH), methylcyclohexanone, isophorone, propylene carbonate, ethylene carbonate, and dihydrolevoglucosenone (Cyrene).<<Ester-based solvent>>

[0023] The ester-based solvent is an organic solvent containing C-C(=O)-O-C in the structure thereof.

[0024] Specific examples of the ester-based solvent include methyl acetate, butyl acetate, ethyl acetate, isopropyl acetate, amyl acetate, isoamyl acetate, ethyl methoxyacetate, ethyl ethoxyacetate, ethylene glycol monoethyl ether acetate, ethylene glycol monopropyl ether acetate, ethylene glycol monobutyl ether acetate, ethylene glycol monophenyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monopropyl ether acetate, diethylene glycol monophenyl ether acetate, diethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate, 2-methoxybutyl acetate, 3-methoxybutyl acetate, 4-methoxybutyl acetate, 3-methyl-3-methoxybutyl acetate, 3-ethyl-3-methoxybutyl acetate, propylene glycol monomethyl ether acetate (PGMEA), propylene glycol monoethyl ether acetate, propylene glycol monopropyl ether acetate, 2-ethoxybutyl acetate, 4-ethoxybutyl acetate, 4-propoxybutyl acetate, 2-methoxypentyl acetate, 3-methoxypentyl acetate, 4-methoxypentyl acetate, 2-methyl-3-methoxypentyl acetate, 3-methyl-3-methoxypentyl acetate, 3-methyl-4-methoxypentyl acetate, 4-methyl-4-methoxypentyl acetate, propylene glycol diacetate, methyl formate, ethyl formate, butyl formate, propyl formate, ethyl lactate, butyl lactate, propyl lactate, ethyl carbonate, propyl carbonate, butyl carbonate, methyl pyruvate, ethyl pyruvate, propyl pyruvate, butyl pyruvate, methyl acetoacetate, ethyl acetoacetate, methyl propionate, ethyl propionate, propyl propionate, isopropyl propionate, methyl 2-hydroxypropionate, ethyl 2-hydroxypropionate, methyl-3-methoxypropionate, ethyl-3-methoxypropionate, ethyl-3-ethoxypropionate, and propyl-3-methoxypropionate.

[0025] In addition, the ester-based solvent may be a cyclic ester-based solvent (lactone-based solvent). Specific examples of the lactone-based solvent include γ-butyrolactone (GBL), ε-caprolactone, γ-valerolactone, and δ-valerolactone.<<Alcohol-based solvent>

[0026] The alcohol-based solvent is an organic solvent containing an alcoholic hydroxy group in the structure thereof.

[0027] The term "alcoholic hydroxy group" denotes a hydroxy group bonded to a carbon atom of an aliphatic hydrocarbon group.

[0028] Specific examples of the alcohol-based solvent include 2-propanol (isopropanol), 1-butanol (n-butanol), 1-hexanol, 1-heptanol, 1-octanol, 2-hexanol, 2-heptanol, 2-octanol, 3-hexanol, 3-heptanol, 3-octanol, 4-octanol, benzyl alcohol, ethylene glycol, diethylene glycol, propylene glycol (PG), and dipropylene glycol.<<Nitrile-based solvent>>

[0029] The nitrile-based solvent is an organic solvent containing a nitrile group in the structure thereof.

[0030] Specific examples of the nitrile-based solvent include acetonitrile, propionitrile, valeronitrile, and butyronitrile.<<Amide-based solvent>>

[0031] The amide-based solvent is an organic solvent containing an amide group in the structure thereof.

[0032] Specific examples of the amide-based solvent include chain-like amide-based solvents such as dimethylacetamide (DMAc), dimethylformamide, and tetramethylurea, and cyclic amide (lactam)-based solvents such as dimethylimidazolidinone, N-methylpyrrolidone, 1-ethyl-2-pyrrolidone, and 1-butyl-2-pyrrolidone.<<Ether-based solvent>>

[0033] The ether-based solvent is an organic solvent containing C-O-C in the structure thereof.

[0034] Specific examples of the ether-based solvent include ethylene glycol monomethyl ether (EGME), ethylene glycol isopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monohexyl ether, propylene glycol monomethyl ether (PGME), propylene glycol monoethyl ether (PGEE), propylene glycol monopropyl ether, propylene glycol monobutyl ether, and diisopropylene glycol monomethyl ether.<<Sulfoxide-based solvent>>

[0035] The sulfoxide-based solvent is an organic solvent containing a sulfinyl group - S(=O)- in the structure thereof.

[0036] Specific examples of the sulfoxide-based solvent include dimethyl sulfoxide (DMSO).<<Sulfone-based solvent>>

[0037] The sulfone-based solvent is an organic solvent containing a sulfonyl group - S(=O) 2 - in the structure thereof.

[0038] Specific examples of the sulfone-based solvent include sulfolane.<<Hydrocarbon-based solvent>>

[0039] The hydrocarbon-based solvent is a hydrocarbon solvent formed of a hydrocarbon which may be halogenated and having no substituent other than a halogen atom. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. Among these, a fluorine atom is preferable.

[0040] Specific examples of the hydrocarbon-based solvent include n-nonane, n-decane, n-undecane, n-dodecane, n-tridecane, n-tetradecane, n-pentadecane, and n-hexadecane.

[0041] Among the examples, the two or more kinds of solvents in the cleaning liquid according to the present embodiment are preferably a mixed solvent of two or more kinds of solvents selected from the group consisting of a ketone-based solvent, an ester-based solvent, an alcohol-based solvent, and an ether-based solvent, more preferably a mixed solvent of two or more kinds of solvents selected from the group consisting of a ketone-based solvent, an ester-based solvent, and an ether-based solvent, and still more preferably a mixed solvent of two or more kinds of solvents selected from the group consisting of an ester-based solvent and an ether-based solvent.

[0042] Further, in the present specification, the two or more kinds of solvents may be two or more kinds of solvents that contain two kinds of compounds and are classified into the same kind. For example, the two or more kinds of solvents may be a mixed solvent of 1-octanone and cyclohexanone, both of which are classified as ketone-based solvents.

[0043] <<Metal remover>>

[0044] Examples of the metal remover contained in the cleaning liquid according to the present embodiment include a metal chelating agent and an organic acid.<<Metal chelating agent>>

[0045] Examples of the metal chelating agent in the present embodiment include an amino carboxylic acid-based chelating agent such as ethylenediaminetetraacetic acid, nitrilotriacetic acid, or diethylenetriaminepentaacetic acid, a phosphonic acid-based chelating agent such as 1-hydroxyethane-1,1-diphosphonic acid or nitrilotris(methylenephosphonic acid), and a compound (A1) represented by General Formula (a-1) (hereinafter, also simply referred to as "compound (A1)"). Among these, the compound (A1) is preferable as the metal chelating agent.

[0046] [In the formula, Ra 1< and Ra 2< each independently represent an alkyl group having 1 to 3 carbon atoms. Ra 3< and Ra 4< each independently represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. Ya 1< and Ya 2< each independently represent a single bond, -O-, -S-, or -N(Ra 5< )-. Ra 5< represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. n represents an integer of 0 to 3.]

[0047] In Formula (a-1), examples of the alkyl group having 1 to 3 carbon atoms as Ra 1< to Ra 5< include a methyl group, an ethyl group, a propyl group, and an isopropyl group.

[0048] In Formula (a-1), Ra 1< and Ra 2< each independently represent preferably a methyl group or an ethyl group and more preferably a methyl group.

[0049] It is preferable that Ra 3< and Ra 4< each represent a hydrogen atom.

[0050] Ya 1< represents preferably a single bond or -O- and more preferably a single bond.

[0051] Ya 2< represents preferably a single bond or -O- and more preferably a single bond.

[0052] n represents preferably 1 or 2 and more preferably 1.

[0053] Among the examples, the compound (A1) is preferably acetylacetone (AcAc) or acetonylacetone and more preferably acetylacetone (AcAc).

[0054] In the cleaning liquid according to the present embodiment, the metal chelating agent may be used alone or in combination of two or more kinds thereof.<<Organic acid>>

[0055] Examples of the organic acid in the present embodiment include a carboxylic acid such as lactic acid (LA), citric acid, malic acid, formic acid, acetic acid, oxalic acid, 2-nitrophenylacetic acid, 2-ethylhexanoic acid, or dodecanoic acid, saccharic acid such as ascorbic acid or glucuronic acid, sulfonic acid such as methanesulfonic acid, benzenesulfonic acid, or p-toluenesulfonic acid, and phosphoric acid ester and phosphoric acid, such as bis(2-ethylhexyl)phosphoric acid.

[0056] Among the examples, the organic acid is preferably a carboxylic acid, more preferably a hydroxy acid, still more preferably at least one selected from the group consisting of lactic acid, citric acid, and malic acid, and particularly preferably lactic acid.

[0057] In the cleaning liquid according to the present embodiment, the organic acid may be used alone or in combination of two or more kinds thereof.

[0058] It is preferable that the cleaning liquid according to the present embodiment contains two or more kinds of the metal removers.

[0059] The cleaning liquid according to the present embodiment contains preferably two or more kinds of metal removers selected from the group consisting of the above-described metal chelating agent and the above-described organic acid, more preferably two or more kinds of metal removers selected from the group consisting of the above-described compound (A1) and the above-described organic acid, and still more preferably two or more kinds of metal removers selected from the group consisting of the above-described compound (A1) and the above-described carboxylic acid.

[0060] In the cleaning liquid according to the present embodiment, among the examples, it is preferable to use the above-described metal chelating agent and the above-described organic acid in combination, more preferable to use the above-described compound (A1) and the above-described organic acid in combination, and still more preferable to use the above-described compound (A1) and the above-described carboxylic acid in combination.<Optional components>

[0061] The cleaning liquid according to the present embodiment may contain optional components other than the above-described solvent and the above-described metal remover within a range where the effects of the present invention are not impaired.

[0062] Examples of the optional components include a pH adjuster and a surfactant.[Distance between Hansen solubility parameters (HSP distance)]

[0063] The cleaning liquid according to the present embodiment contains the above-described two or more kinds of solvents and metal removers, and the distance (HSP distance) between the Hansen solubility parameter of the cleaning liquid and the Hansen solubility parameter of dimethylacetamide (DMAc) is 1.0 or less, preferably 0.8 or less, and more preferably 0.5 or less.

[0064] In a case where the HSP distance of the cleaning liquid according to the present embodiment is less than or equal to the above-described upper limits, the effect of removing impurity stains of the cleaning liquid is enhanced regardless of the material of the cleaning target. The HSP distance of the cleaning liquid according to the present embodiment is preferably as low as possible from the viewpoint of enhancing the effect of removing impurity stains of the cleaning liquid.

[0065] The term "Hansen solubility parameter" in the present specification is a numerical constant that is theoretically calculated and is a useful tool for predicting the ability of a solvent material to dissolve a specific solute.

[0066] The Hansen solubility parameter can be used as a measure of the overall strength and selectivity of a material by combining the following three Hansen solubility parameters (δ d (dispersion force term), δ p (polar term), and δ h (hydrogen bond term)) that are experimentally and theoretically derived. The Hansen solubility parameter is in units of MPa 0.5< or (J / cc) 0.5< . δ d : energy derived from dispersion force between molecules δ p : energy derived from polar force between molecules δ h : energy derived from hydrogen bond force between molecules

[0067] The "Hansen solubility parameter" can be calculated, for example, by Hansen Solubility from "Molecular Modeling Pro" software, version 5.1.9 (ChemSW, Fairfield CA, www.chemsw.com) or Dynacomp Software.

[0068] Since the cleaning liquid according to the present embodiment is a mixture, the Hansen solubility parameter of the cleaning liquid according to the present embodiment can be determined as follows.

[0069] For example, in a case where a cleaning liquid CS formed of a solvent S 1< (δ ds1 , δ ps1 , δ hs1 ), a solvent S 2< (δ ds2 , δ ps2 , δ hs2 ), a metal remover B 1< (δ dB1 , δ pB1 , δ hB1 ), and a metal remover B 2< (δ dB2 , δ pB2 , δ hB2 ) has a blending amount of the solvent S 1< of a, a blending amount of the solvent S 2< of b, a blending amount of the metal remover B 1< of c, and a blending amount of the metal remover B 2< of d, δ dcs (dispersion force term), δ pcs (polar term), and δ hcs (hydrogen bond term) of the cleaning liquid CS are calculated by the following equations. It is noted that a + b + c + d = 100. δ dcs = δ ds 1 × a + δ ds 2 × b + δ dB 1 × c + δ dB 2 × d / 100 δ pcs = δ ps 1 × a + δ ps 2 × b + δ pB 1 × c + δ pB 2 × d / 100 δ hcs = δ hs 1 × a + δ hs 2 × b + δ hB 1 × c + δ hB 2 × d / 100

[0070] The distance (HSP distance) between the Hansen solubility parameter of the cleaning liquid CS (cleaning liquid according to the present embodiment) and the Hansen solubility parameter of dimethylacetamide (DMAc) is calculated by Equation (1). HSP distance = 4 δ dcs − δ dDMAc 2 + δ pcs − δ pDMAc 2 + δ hcs − δ hDMA c 2 0.5

[0071] Further, a value of 16.8 is used for the dispersion force term (δ dDMAc ) of dimethylacetamide, a value of 11.5 is used for the polar term (δ pDMAc ), and a value of 9.4 is used for the hydrogen bond term (δ hDMAc ).

[0072] The HSP distance in the cleaning liquid according to the present embodiment can be controlled, for example, by adopting a solvent or a metal remover close to the values of the dispersion force term (δ dDMAc ), the polar term (δ pDMAc ), and the hydrogen bond term (δ hDMAc ) of dimethylacetamide or by selecting a combination of each component.[Content of metal impurities]

[0073] The content of the metal impurities in the cleaning liquid according to the present embodiment is 0.1 × 10 -9< parts by mass or greater and 10 2< × 10 -6< parts by mass or less, preferably 0.25 × 10 -9< parts by mass or greater and 1 × 10 -6< (1000 × 10 -9< ) parts by mass or less, more preferably 0.5 × 10 -9< parts by mass or greater and 500 × 10 -9< parts by mass or less, still more preferably 0.75 × 10 -9< parts by mass or greater and 100 × 10 -9< parts by mass or less, and particularly preferably 1 × 10 -9< parts by mass or greater and 20 × 10 -9< parts by mass or less with respect to 100 parts by mass of the total amount of the solvents and the metal remover.

[0074] In a case where the content of the metal impurities in the cleaning liquid according to the present embodiment is in the above-described ranges, the effect of removing the impurity stains of the cleaning liquid is further enhanced regardless of the material of the cleaning target.

[0075] The term "metal impurities" contained in the cleaning liquid according to the present embodiment denotes metal components including metal elements selected from the group consisting of Na, Ca, K, Fe, Ti, Al, Ni, Zn, Cr, and Mg.

[0076] The term "content of the metal impurities" denotes the total content of the metal components including metal elements selected from the group consisting of Na, Ca, K, Fe, Ti, Al, Ni, Zn, Cr, and Mg.

[0077] The mass of the metal impurities in the cleaning liquid is determined by inductively coupled plasma mass spectrometry.

[0078] In practice, the content (mass fraction) of the metal impurities in the cleaning liquid is obtained by specifying the metal elements to be measured and measuring the total amount thereof.

[0079] The metal elements to be measured are, for example, 12 to 28 elements, and further include any metal element of Li, V, Mn, Co, Cu, Ge, As, Sr, Zr, Mo, Ag, Cd, Sn, Sb, Ba, W, Au, or Pb in addition to Na, Ca, K, Fe, Ti, Al, Ni, Zn, Cr, and Mg.

[0080] The content of the metal impurities in the cleaning liquid can be adjusted by controlling the amount of the metal impurities contained in the solvent or the metal remover to be blended; or can be adjusted by mixing the solvent, the metal remover, and the optional component and adding a metal element separately from these; or can be adjusted by separating and removing an excess metal element.

[0081] Suitable examples of the cleaning liquid according to the present embodiment include a composition (X) containing a mixed solvent of two or more kinds of solvents selected from the group consisting of a ketone-based solvent, an ester-based solvent, an alcohol-based solvent, and an ether-based solvent, the above-described metal chelating agent, and the above-described organic acid, in which the HSP distance is 1.0 or less, and the content of the metal impurities is 0.1 × 10 -9< parts by mass or greater and 10 2< × 10 -6< parts by mass or less with respect to 100 parts by mass of the total amount of the mixed solvent, the metal chelating agent, and the organic acid.

[0082] The distance (HSP distance) between the Hansen solubility parameter of the composition (X) and the Hansen solubility parameter of DMAc is 1.0 or less, preferably 0.8 or less, more preferably 0.5 or less, still more preferably 0.4 or less, and particularly preferably 0.3 or less, and it is preferable that the distance thereof is as small as possible.

[0083] The mixed solvent in the composition (X) is more preferably a mixed solvent of one or more kinds of solvents selected from the group consisting of a ketone-based solvent and an ester-based solvent (hereinafter, also referred to as "solvent S1") and one or more kinds of solvents selected from the group consisting of an alcohol-based solvent and an ether-based solvent (hereinafter, also referred to as "solvent S2"), still more preferably a mixed solvent of an ester-based solvent and an ether-based solvent, and particularly preferably a mixed solvent of a lactone-based solvent and an ether-based solvent.

[0084] For example, in a case where the two or more kinds of solvents in the composition (X) are a mixed solvent of the solvent S1 and the solvent S2, the mixing ratio of the solvent S1 to the solvent S2 (solvent S1:solvent S2) is preferably 20:80 to 80:20, more preferably 30:70 to 70:30, and still more preferably 40:60 to 60:40 in terms of the mass ratio.

[0085] Examples of a suitable combination of the two or more kinds of solvents in the composition (X) include a mixed solvent of one or more kinds of solvents selected from the group consisting of γ-butyrolactone, ε-caprolactone, and γ-valerolactone and one or more kinds of solvents selected from the group consisting of EGME, PGME, and PGEE, and a mixed solvent of dihydrolevoglucosenone (Cyrene) and PG.

[0086] Among these, as a suitable combination of the two or more kinds of solvents, a mixed solvent of one or more kinds of solvents selected from the group consisting of γ-butyrolactone, ε-caprolactone, and γ-valerolactone and one or more kinds of solvents selected from the group consisting of EGME, PGME, and PGEE is preferable, and a mixed solvent of γ-butyrolactone and PGME is more preferable.

[0087] The metal chelating agent in the composition (X) is preferably a compound (A1) and more preferably acetylacetone (AcAc).

[0088] The organic acid in the composition (X) is preferably a carboxylic acid, more preferably a hydroxy acid, and still more preferably lactic acid.

[0089] The content of the metal impurities in the composition (X) is 0.1 × 10 -9< parts by mass or greater and 10 2< × 10 -6< parts by mass or less, preferably 0.25 × 10 -9< parts by mass or greater and 1 × 10 -6< (1000 × 10 -9< ) parts by mass or less, more preferably 0.5 × 10 -9< parts by mass or greater and 500 × 10 -9< parts by mass or less, still more preferably 0.75 × 10 -9< parts by mass or greater and 100 × 10 -9< parts by mass or less, and particularly preferably 1 × 10 -9< parts by mass or greater and 20 × 10 -9< parts by mass or less with respect to 100 parts by mass of the total amount of the mixed solvent, the metal chelating agent, and the organic acid.

[0090] The content of each of the mixed solvent, the metal chelating agent, and the organic acid in the composition (X) is appropriately selected such that the HSP distance reaches 1.0 or less.

[0091] The content of the mixed solvent in the composition (X) is preferably 90% to 99.5% by mass and more preferably 95% to 99% by mass with respect to the total amount of the composition (X).

[0092] The content of the metal chelating agent in the composition (X) is preferably 0.1% to 9% by mass, more preferably 0.5% to 9% by mass, and still more preferably 0.5% to 5% by mass with respect to the total amount of the composition (X).

[0093] The proportion of the compound (A1) in the metal chelating agent is preferably 50% by mass or more and more preferably 75% by mass or more, and may be 100% by mass with respect to the total mass of the metal chelating agent.

[0094] The content of the organic acid in the composition (X) is preferably 0.1% to 9% by mass, more preferably 0.5% to 9% by mass, and still more preferably 0.5% to 5% by mass with respect to 100% by mass of the total amount of the composition (X).

[0095] The proportion of the carboxylic acid in the organic acid is preferably 50% by mass or greater and more preferably 75% by mass or greater, and may be 100% by mass with respect to the total mass of the organic acid.

[0096] The composition (X) may further contain the optional components described above as necessary, in addition to the mixed solvent, the metal chelating agent, and the organic acid.

[0097] The cleaning liquid of the present embodiment is a cleaning liquid useful for cleaning a membrane.

[0098] The form and the shape of the membrane are not particularly limited, and examples thereof include a flat membrane, a hollow fiber membrane, a tubular membrane, a spiral membrane, and a thin membrane (film).

[0099] In addition, the material of the membrane is not particularly limited, and examples thereof include polyolefin (polyethylene, polypropylene, or the like), polysulfone, polyacrylonitrile, polyamide, polyimide, polyvinyl alcohol, a cellulose acetate-based material, a fluoropolymer, and ceramic.

[0100] In addition, the cleaning liquid of the present embodiment is also useful for removing impurity stains from various cleaning targets. Examples of the various cleaning targets include each pipe in a production line, a container to be used, and an instrument. For example, the cleaning liquid of the present embodiment can be used for cleaning a cleaning target selected from the group consisting of a metal pipe, a resin pipe, a glass pipe, a metal joint, a resin joint, a glass joint, a filter, a chemical liquid container, a measurement cell, and a chromatography column.

[0101] The cleaning liquid of the present embodiment described above contains two or more kinds of solvents and a metal remover. In addition, the distance (HSP distance) between the Hansen solubility parameter of the cleaning liquid and the Hansen solubility parameter of dimethylacetamide (DMAc) is 1.0 or less, and the content of the metal impurities is 0.1 × 10 -9< parts by mass or greater and 10 2< × 10 -6< parts by mass or less with respect to 100 parts by mass of the total amount of the solvents and the metal remover.

[0102] The reason is not clear, but a satisfactory cleaning and removing effect is exhibited even with respect to both a polar cleaning target and a non-polar cleaning target in a case where such a cleaning liquid contains a metal remover while the Hansen solubility parameter of the entire cleaning liquid is adjusted to be close to that of DMAc. In addition, since the cleaning liquid contains a metal remover, the removability of metal impurity stains is excellent.

[0103] Further, such a cleaning liquid is intentionally made to contain a specific content of metal impurities. In this manner, the effect of removing impurity stains from various cleaning targets is further enhanced, and particularly, the effect of removing metal impurity stains is greatly enhanced.(Second aspect: cleaning method)

[0104] According to an embodiment, the cleaning method is a method of cleaning a cleaning target by bringing the above-described cleaning liquid into contact with the cleaning target.

[0105] Examples of the cleaning target in the cleaning method of the present embodiment include a membrane, each pipe in a production line, a container to be used, and an instrument. For example, the cleaning target may be a membrane such as a flat membrane, a hollow fiber membrane, a tubular membrane, a spiral membrane, or a thin membrane (film). Alternatively, the cleaning target may be selected from the group consisting of a metal pipe, a resin pipe, a glass pipe, a metal joint, a resin joint, a glass joint, a filter, a chemical liquid container, a measurement cell, and a chromatography column.

[0106] More specific examples of a cleaning operation of cleaning the cleaning target by bringing the above-described cleaning liquid into contact with the cleaning target include a method of immersing a cleaning target in the cleaning liquid and a method of spraying the cleaning liquid onto a cleaning target.

[0107] The cleaning operation may be performed only once or a plurality of times.

[0108] In addition, the cleaning liquid may be heated or the cleaning operation may be performed at room temperature (for example, 23°C) during the cleaning operation.

[0109] The cleaning method of the present embodiment may include a drying step of drying the cleaning target cleaned by the above-described cleaning operation. A known method such as a method of air drying at room temperature, a method of placing the cleaned cleaning target in a constant-temperature tank and heating the cleaning target, or a method of vacuum drying can be applied in the drying step.

[0110] According to the cleaning method of the present embodiment described above, since the above-described cleaning liquid is used, the cleaning method has excellent stain removability for organic impurities or metal impurities from various cleaning targets.

[0111] The cleaning method according to another embodiment is a method further including, before or after a step of cleaning the cleaning target by bringing the above-described cleaning liquid into contact with the cleaning target (hereinafter, also referred to as "cleaning step A"), a step of cleaning the cleaning target by bringing the cleaning target into contact with a second cleaning liquid different from the cleaning liquid (hereinafter, also referred to as "cleaning step B").

[0112] The cleaning method according to another embodiment described above may include (i) a step of cleaning the cleaning target by bringing the second cleaning liquid different from the above-described cleaning liquid (referred to as a first cleaning liquid) into contact with the cleaning target and a step of cleaning the cleaning target by bringing the first cleaning liquid into contact with the cleaning target cleaned with the second cleaning liquid, (ii) a step of cleaning the cleaning target by bringing the above-described cleaning liquid (first cleaning liquid) into contact with the cleaning target and a step of cleaning the cleaning target by bringing the second cleaning liquid different from the first cleaning liquid into contact with the cleaning target cleaned with the first cleaning liquid, or (iii) a step of cleaning the cleaning target by bringing the second cleaning liquid different from the above-described cleaning liquid (first cleaning liquid) into contact with the cleaning target, a step of cleaning the cleaning target by bringing the first cleaning liquid into contact with the cleaning target cleaned with the second cleaning liquid, and a step of cleaning the cleaning target by bringing a third cleaning liquid different from the first cleaning liquid into contact with the cleaning target cleaned with the first cleaning liquid.

[0113] In the item (iii), the second cleaning liquid and the third cleaning liquid may be the same as or different from each other.· Cleaning step B

[0114] Examples of the method of cleaning the cleaning target by bringing the second cleaning liquid different from the above-described cleaning liquid in the cleaning step B into contact with the cleaning target include the same method as the method in the above-described cleaning step A (a method of immersing the cleaning target in the cleaning liquid, a method of spraying the cleaning liquid onto the cleaning target, or the like).

[0115] The cleaning step B may be performed only once or a plurality of times before or after the cleaning step A.· Second cleaning liquid and third cleaning liquid

[0116] Examples of the cleaning liquid (the second cleaning liquid or the third cleaning liquid) different from the above-described cleaning liquid include a cleaning liquid containing a solvent and no metal remover. Typical examples of the cleaning liquid (the second cleaning liquid or the third cleaning liquid) include a cleaning liquid formed of only a solvent.

[0117] Examples of the solvent in the cleaning liquid (the second cleaning liquid or the third cleaning liquid) include polar solvents such as a ketone-based solvent, an ester-based solvent, an alcohol-based solvent, a nitrile-based solvent, an amide-based solvent, an ether-based solvent, a sulfoxide-based solvent, and a sulfone-based solvent, and non-polar solvents such as a hydrocarbon-based solvent, and specific examples thereof include the same solvents as those in the above-described cleaning liquid.

[0118] Among these, the cleaning liquid (the second cleaning liquid or the third cleaning liquid) contains preferably an alcohol-based solvent, more preferably an alcohol-based solvent having 1 to 5 carbon atoms, and still more preferably 2-propanol (isopropanol).

[0119] According to another embodiment of the cleaning method, a method including the cleaning step A and a step of cleaning the cleaning target by bringing the cleaning target into contact with an alcohol-based solvent (preferably 2-propanol) before or after the cleaning step A is suitable.

[0120] According to another embodiment, the cleaning method may further include a drying step of drying the cleaning target cleaned in the cleaning step A or the cleaning step B.

[0121] A known method such as a method of air drying at room temperature, a method of placing the cleaned cleaning target in a constant-temperature tank and heating the cleaning target, or a method of vacuum drying can be applied in the drying step.

[0122] According to another embodiment of the cleaning method described above, since the cleaning method further includes the cleaning step B in addition to the cleaning step A described above, the effect of removing impurity stains adhering to the cleaning target is further enhanced as compared with the cleaning method including only the cleaning step A described above.Examples

[0123] Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.<Preparation of cleaning liquid>

[0124] Each component was mixed according to the composition listed in Table 1 to prepare a cleaning liquid of each example.(Example 1)

[0125] In a cleaning liquid of Example 1, the content of metal impurities after mixing each component was 1.1 × 10 -9< parts by mass in total of 28 elements of metal elements with respect to 100 parts by mass of the total amount of the solvent and the metal remover, as a result of [Measurement of content of metal impurities] described below.(Examples 2 and 3)

[0126] A cleaning liquid of Example 2 in which the content of metal impurities was 4.5 × 10 -9< parts by mass and a cleaning liquid of Example 3 in which the content of metal impurities was 23.9 × 10 -9< parts by mass with respect to 100 parts by mass of the total amount of the solvent and the metal remover were prepared by adding a standard solution for metal analysis in a solvent (manufactured by Agilent Technologies, Inc., part number: 5190-8715) as a mineral oil to the cleaning liquid of Example 1.(Comparative Examples 1 and 2)

[0127] As a cleaning liquid of Comparative Example 1, OK73 thinner was used. The composition of the OK73 thinner was a mixed solvent of PGMEA and PGME at a mass ratio of 30:70.

[0128] As a cleaning liquid of Comparative Example 2, isopropanol was used. The content of metal impurities in the isopropanol was set to 2.5 × 10 -9< parts by mass with respect to 100 parts by mass of the total amount of the solvent and the metal remover. [Table 1]Cleaning liquidSolventMetal removerHSP distanceProportion of metal impurities with respect to 100 parts by mass of total amount of solvent and metal remover (parts by mass)Comparative Example 1PGMEA

[30] PGME

[70] --6.150Example 1GBL

[49] PGME

[49] AcAc [1]LA [1]0.271.1 × 10 -9< Example 2GBL

[49] PGME

[49] AcAc [1]LA [1]0.274.5 × 10 -9< Example 3GBL

[49] PGME

[49] AcAc [1]LA [1]0.2723.9 × 10 -9< Comparative Example 2IPA

[100] ---5.612.5 × 10 -9<

[0129] The abbreviations in the table represent the following compounds. The numerical values in the brackets in the table are blending amounts (parts by mass). GBL: γ-butyrolactone PGME: propylene glycol monomethyl ether PGMEA: propylene glycol monomethyl ether acetate AcAc: acetylacetone LA: lactic acid IPA: isopropanol [Calculation of HSP distance]

[0130] The Hansen solubility parameter of each component of the cleaning liquid was calculated using "Molecular Modeling Pro" software, version 5.1.9 (ChemSW, Fairfield CA, www.chemsw.com). The Hansen solubility parameter of each component is shown below.

[0131] A value of 18 was used as the dispersion force term (δ dGBL ) of GBL, a value of 16.6 was used as the polar term (δ pGBL ) of GBL, and a value of 7.4 was used as the hydrogen bond term (δ hGBL ) of GBL.

[0132] A value of 15.6 was used as the dispersion force term (δ dPGME ) of PGME, a value of 6.3 was used as the polar term (δ pPGME ) of PGME, and a value of 11.6 was used as the hydrogen bond term (δ hPGME ) of PGME.

[0133] A value of 16.1 was used as the dispersion force term (δ dAcAc ) of AcAc, a value of 10 was used as the polar term (δ pAcAc ) of AcAc, and a value of 6.2 was used as the hydrogen bond term (δ hAcAc ) of AcAc.

[0134] A value of 17 was used as the dispersion force term (δ dLA ) of LA, a value of 8.3 was used as the polar term (δ pLA ) of LA, and a value of 28.4 was used as the hydrogen bond term (δ hLA ) of LA.

[0135] A value of 15.6 was used as the dispersion force term (δ dPGMEA ) of PGMEA, a value of 6.3 was used as the polar term (δ pPGMEA ) of PGMEA, and a value of 7.7 was used as the hydrogen bond term (δ hPGMEA ) of PGMEA.

[0136] A value of 16.3 was used as the dispersion force term (δ dIPA ) of IPA, a value of 6.8 was used as the polar term (δ pIPA ) of IPA, and a value of 6.5 was used as the hydrogen bond term (δ hIPA ) of IPA.

[0137] The dispersion force terms (δ dt ), the polar terms (δ pt ), and the hydrogen bond terms (δ ht ) of the cleaning liquids of Examples 1 to 3 were obtained as follows. δ dt = δ dGBL × 49 + δ dPGME × 49 + δ dAcAc × 1 + δ dLA × 1 / 100 δ pt = δ pGBL × 49 + δ pPGME × 49 + δ dAcAc × 1 + δ dLA × 1 / 100 δ ht = δ hGBL × 49 + δ hPGME × 49 + δ dAcAc × 1 + δ dLA × 1 / 100

[0138] The dispersion force term (δ dt ), the polar term (δ pt ), and the hydrogen bond term (δ ht ) of the cleaning liquid of Comparative Example 1 were determined as follows. δ dt = δ dPGMEA × 30 + δ dPGME × 70 / 100 δ pt = δ pPGMEA × 30 + δ pPGME × 70 / 100 δ ht = δ hPGMEA × 30 + δ hPGME × 70 / 100

[0139] The dispersion force term (δ dt ), the polar term (δ pt ), and the hydrogen bond term (δ ht ) of the cleaning liquid of Comparative Example 2 were determined as follows. δ dt = δ dIPA × 100 / 100 δ pt = δ pIPA × 100 / 100 δ ht = δ hIPA × 100 / 100

[0140] In Examples 1 to 3, the distance (HSP distance) between the Hansen solubility parameter (MPa 0.5< ) of the cleaning liquid and the Hansen solubility parameter (MPa 0.5< ) of dimethylacetamide was calculated according to Equation (1t).

[0141] A value of 16.8 was used as the dispersion force term (δ dDMAc ) of dimethylacetamide, a value of 11.5 was used as the polar term (δ pDMAc ), and a value of 9.4 was used as the hydrogen bond term (δ hDMAc ). HSP distance = 4 δ dt − δ dDMAc 2 + δ dp − δ pDMAc 2 + δ ht − δ hDMAc 2 0.5

[0142] In Comparative Examples 1 and 2, the distance (HSP distance) between the Hansen solubility parameter (MPa 0.5< ) of the cleaning liquid and the Hansen solubility parameter (MPa 0.5< ) of dimethylacetamide was also calculated in the same manner as in Examples 1 to 3.[Measurement of content of metal impurities]

[0143] The content of the metal impurities in the cleaning liquid was measured using an inductively coupled plasma mass spectrometer (trade name: ICP-MS 8900, manufactured by Agilent Technologies, Inc.).

[0144] The measured metal elements were 28 elements of Na, Ca, K, Fe, Ti, Al, Ni, Zn, Cr, Mg, Li, V, Mn, Co, Cu, Ge, As, Sr, Zr, Mo, Ag, Cd, Sn, Sb, Ba, W, Au, and Pb, and the total amount thereof was defined as the content (mass fraction) of the metal impurities in the cleaning liquid.

[0145] The metal impurity stains in the cleaning evaluation described below, that is, the total metal amount in the OK73 thinner was also measured in the same manner as described above.<Cleaning evaluation (1)>

[0146] The removability of the metal impurity stains was evaluated by the cleaning method described below using the cleaning liquid of each example with respect to a porous polyethylene film serving as a cleaning target. The results thereof are listed in Table 2.(Comparative Example 1-1)

[0147] 100 mL of the cleaning liquid (OK73 thinner) of Comparative Example 1 was added to a container.

[0148] A porous polyethylene film with a size of 1000 cm 2< was placed in the container and immersed for 1 day.

[0149] Thereafter, the porous polyethylene film was taken out, and the total metal amount in the OK73 thinner was measured, which was 37.4 ppb.(Example 1-1)

[0150] 100 mL of the cleaning liquid of Example 1 was added to a container.

[0151] A porous polyethylene film with a size of 1000 cm 2< was placed in the container and immersed for 1 day.

[0152] Thereafter, the cleaning liquid was discarded from the container, isopropanol (content of metal impurities: 2.5 ppb) was added thereto, and the porous polyethylene film was rinsed.

[0153] After the rinsing, the isopropanol was discarded from the container and replaced with 100 mL of the OK73 thinner (cleaning liquid of Comparative Example 1), and the porous polyethylene film was immersed in the OK73 thinner for 1 day.

[0154] Thereafter, the porous polyethylene film was taken out, and the total metal amount in the OK73 thinner was measured, which was 0.6 ppb.(Examples 1-2 and 1-3)

[0155] The removability of the metal impurity stains from the cleaning target was evaluated by using the above-described cleaning method in the same manner as described above except that the cleaning liquid of Example 1 was changed to each of the cleaning liquids of Examples 2 and 3.

[0156] In a case where the cleaning liquid of Example 2 was used, the total metal amount in the OK73 thinner was 0.1 ppb.

[0157] In a case where the cleaning liquid of Example 3 was used, the total metal amount in the OK73 thinner was 2.1 ppb.(Comparative Example 1-2)

[0158] 100 mL of the cleaning liquid of Comparative Example 2 was added to a container.

[0159] A porous polyethylene film with a size of 1000 cm 2< was placed in the container and immersed for 1 day.

[0160] Thereafter, the cleaning liquid was discarded from the container, isopropanol (content of metal impurities: 2.5 ppb) was added thereto, and the porous polyethylene film was rinsed.

[0161] After the rinsing, the isopropanol was discarded from the container and replaced with 100 mL of the OK73 thinner (cleaning liquid of Comparative Example 1), and the porous polyethylene film was immersed in the OK73 thinner for 1 day.

[0162] Thereafter, the porous polyethylene film was taken out, and the total metal amount in the OK73 thinner was measured, which was 15.7 ppb. [Table 2]Total metal amount (ppb)Comparative Example 1-137.4Example 1-10.6Example 1-20.1Example 1-32.1Comparative Example 1-215.7

[0163] As shown in the results listed in Table 2, it can be confirmed that, in a case where the cleaning liquids of Examples 1 to 3 were used, the total metal amounts were smaller than those in a case where the cleaning liquids of Comparative Examples 1 and 2 were used, and thus, according to the cleaning liquid and the cleaning method to which the present invention was applied, the effect of removing the metal impurity stains from the cleaning target was greatly enhanced.<Cleaning evaluation (2)>

[0164] The removability of the impurity stains was evaluated based on the number of defects on the wafer surface as an index by the cleaning method described below using the cleaning liquid of each example with respect to a chemical liquid supply line (HDPE 2 nm filter connection, pipe) serving as a cleaning target. The results thereof are listed in Table 3.(Comparative Example 2-1)

[0165] An HDPE 2 nm filter (manufactured by Pall Corporation) was connected to the chemical liquid supply line of a resist chemical liquid coating and developing device (Lithius ProZ, manufactured by Tokyo Electron Limited), and 3 GAL of the cleaning liquid (OK73 thinner) of Comparative Example 1 was allowed to pass through the filter.

[0166] A 12-inch wafer was coated with the OK73 thinner allowed to pass through the HDPE 2 nm filter and baked at 80°C for 60 seconds. Thereafter, the number of defects having a size of 17 nm or greater was measured by a wafer surface defect device (Surf Scan SP5 XP, manufactured by KLA Tencor), and the number of defects in a case where only the OK73 thinner was allowed to pass through the filter was 584.(Example 2-1)

[0167] An HDPE 2 nm filter (manufactured by Pall Corporation) was connected to the chemical liquid supply line of a resist chemical liquid coating and developing device (Lithius ProZ, manufactured by Tokyo Electron Limited), 1 GAL of the cleaning liquid of Example 1 was allowed to pass through the filter, the cleaning liquid was switched to the OK73 thinner, and 2 GAL of the OK73 thinner was allowed to pass through the filter.

[0168] A 12-inch wafer was coated with the OK73 thinner, which had been allowed to pass through the HDPE 2 nm filter, and baked at 80°C for 60 seconds. Thereafter, the number of defects having a size of 17 nm or greater was measured by the wafer surface defect device, and the number of defects of the OK73 thinner in a case where only the OK73 thinner was allowed to pass through the filter was 359, but was reduced to 44.(Example 2-2)

[0169] The cleaning liquid of Example 1 was changed to the cleaning liquid of Example 2, the cleaning liquid of Example 2 was allowed to pass through the chemical liquid supply line, 1 L of the cleaning liquid of Example 2 was allowed to pass through after immersion in the chemical liquid supply line for 1 day, and switched to the OK73 thinner, and 1 L of the OK73 thinner was allowed to pass through.

[0170] A 12-inch wafer was coated with the OK73 thinner, which had been allowed to pass through, and baked at 80°C for 60 seconds. Thereafter, the number of defects having a size of 17 nm or greater was measured by the wafer surface defect device, and the number of defects was reduced to 53.(Example 2-3)

[0171] The cleaning liquid of Example 1 was changed to the cleaning liquid of Example 3, the cleaning liquid of Example 3 was allowed to pass through the chemical liquid supply line, 1 L of the cleaning liquid of Example 3 was allowed to pass through after immersion in the chemical liquid supply line for 1 day, and switched to the OK73 thinner, and 1 L of the OK73 thinner was allowed to pass through.

[0172] A 12-inch wafer was coated with the OK73 thinner, which had been allowed to pass through, and baked at 80°C for 60 seconds. Thereafter, the number of defects having a size of 17 nm or greater was measured by the wafer surface defect device, and the number of defects was reduced to 47. [Table 3]Number of defects on wafer surface (pieces)Comparative Example 2-1584Example 2-144Example 2-253Example 2-347

[0173] As shown in the results listed in Table 3, it can be confirmed that, in a case where the cleaning liquids of Examples 1 to 3 were used, the number of defects on the wafer surface was reduced as compared with a case where only the cleaning liquid of Comparative Example 1 was used, and thus the effect of removing impurity stains from the cleaning target could be enhanced by applying the present invention.

[0174] Hereinbefore, preferred examples of the present invention have been described, but the present invention is not limited to these examples. Configurations can be added, omitted, and replaced, and other modifications can be made within a range not departing from the gist of the present invention. The present invention is not limited by the description above, but only by the scope of the appended claims.

Examples

example 1

(Example 1)

[0125]In a cleaning liquid of Example 1, the content of metal impurities after mixing each component was 1.1 × 10 -9< parts by mass in total of 28 elements of metal elements with respect to 100 parts by mass of the total amount of the solvent and the metal remover, as a result of [Measurement of content of metal impurities] described below.

examples 2 and 3

(Examples 2 and 3)

[0126]A cleaning liquid of Example 2 in which the content of metal impurities was 4.5 × 10 -9< parts by mass and a cleaning liquid of Example 3 in which the content of metal impurities was 23.9 × 10 -9< parts by mass with respect to 100 parts by mass of the total amount of the solvent and the metal remover were prepared by adding a standard solution for metal analysis in a solvent (manufactured by Agilent Technologies, Inc., part number: 5190-8715) as a mineral oil to the cleaning liquid of Example 1.

(Comparative Examples 1 and 2)

[0127]As a cleaning liquid of Comparative Example 1, OK73 thinner was used. The composition of the OK73 thinner was a mixed solvent of PGMEA and PGME at a mass ratio of 30:70.

[0128]As a cleaning liquid of Comparative Example 2, isopropanol was used. The content of metal impurities in the isopropanol was set to 2.5 × 10 -9

[Table 1]

Cleaning liquidSolventMetal removerHSP distanceProportion of metal impurities with respect to 100 parts by ma...

example 1-1

(Example 1-1)

[0150]100 mL of the cleaning liquid of Example 1 was added to a container.

[0151]A porous polyethylene film with a size of 1000 cm 2< was placed in the container and immersed for 1 day.

[0152]Thereafter, the cleaning liquid was discarded from the container, isopropanol (content of metal impurities: 2.5 ppb) was added thereto, and the porous polyethylene film was rinsed.

[0153]After the rinsing, the isopropanol was discarded from the container and replaced with 100 mL of the OK73 thinner (cleaning liquid of Comparative Example 1), and the porous polyethylene film was immersed in the OK73 thinner for 1 day.

[0154]Thereafter, the porous polyethylene film was taken out, and the total metal amount in the OK73 thinner was measured, which was 0.6 ppb.

(Examples 1-2 and 1-3)

[0155]The removability of the metal impurity stains from the cleaning target was evaluated by using the above-described cleaning method in the same manner as described above except that the cleaning liquid of Ex...

TECHNICAL FIELD

[0001] The present invention relates to a cleaning liquid and a cleaning method.

[0002] Priority is claimed on Japanese Patent Application No. 2023-187033, filed October 31, 2023, the content of which is incorporated herein by reference.BACKGROUND ART

[0003] A cleaning liquid is required to be selected according to the type of stain and the material of a cleaning target.

[0004] In the industrial field, for example, in a film to be produced from a high-molecular-weight material, particularly a porous film, the influence of organic impurity stains such as high-molecular-weight residues derived from the high-molecular-weight material or metal impurity stains derived from a metal catalyst and the like used in a film production step is a problem.

[0005] In dealing with this problem, a film cleaning liquid in which a specific solvent is selected according to the material of the film has been proposed (see Patent Document 1).Citation ListPatent Document

[0006] Patent Document 1: Japanese Unexamined Patent Application, First Publication No. 2017-202479SUMMARY OF INVENTIONTechnical Problem

[0007] In the related art, in a filter to be produced from a porous film, a chemical liquid purified by the filter may be contaminated unintentionally. The contamination source is a high-molecular-weight or low-molecular-weight organic impurity or a metal impurity, which coexists in the filter. These impurities are not only derived from a high-molecular-weight material or a metal catalyst, but are also easily mixed from various places such as each pipe in a production line, a container to be used, and an instrument. On the other hand, with the miniaturization and high performance of industrial products, there is a strong demand for further reduction of the impurity stains as described above.

[0008] The present invention has been made in consideration of the above-described circumstances, and an object thereof is to provide a cleaning liquid having improved removability of impurity stains, and a cleaning method using the cleaning liquid. Solution to Problem

[0009] In order to solve the above-described problems, the present invention employs the following configurations.

[0010] According to a first aspect of the present invention, there is provided a cleaning liquid containing: a solvent and a metal remover, in which the cleaning liquid contains two or more kinds of solvents, a distance (HSP distance) between a Hansen solubility parameter of the cleaning liquid and a Hansen solubility parameter of dimethylacetamide is 1.0 or less, and a content of a metal impurity is 0.1 × 10 -9< parts by mass or greater and 10 2< × 10 -6< parts by mass or less with respect to 100 parts by mass of a total amount of the solvents and the metal remover.

[0011] According to a second aspect of the present invention, there is provided a cleaning method including cleaning a cleaning target by bringing the cleaning liquid according to the first aspect into contact with the cleaning target.Advantageous Effects of Invention

[0012] According to the present invention, it is possible to provide a cleaning liquid having improved removability of impurity stains, and a cleaning method using the cleaning liquid.

[0013] Such a cleaning liquid and a cleaning method using the cleaning liquid are useful for removing impurity stains from various cleaning targets.DESCRIPTION OF EMBODIMENTS(First aspect: cleaning liquid)

[0014] According to an embodiment, a cleaning liquid contains two or more kinds of solvents and a metal remover.

[0015] In the present embodiment, a distance (HSP distance) between a Hansen solubility parameter of the cleaning liquid and a Hansen solubility parameter of dimethylacetamide is 1.0 or less.

[0016] In addition, a content of a metal impurity in the cleaning liquid of the present embodiment is 0.1 × 10 -9< parts by mass or greater and 10 2< × 10 -6< parts by mass or less with respect to 100 parts by mass of a total amount of the solvents and the metal remover.<Solvent>

[0017] The cleaning liquid of the present embodiment contains two or more kinds of solvents.

[0018] The solvents contained in the cleaning liquid of the present embodiment can be appropriately selected from known organic solvents such that the HSP distance is 1.0 or less. Examples of the organic solvents include polar solvents such as a ketone-based solvent, an ester-based solvent, an alcohol-based solvent, a nitrile-based solvent, an amide-based solvent, an ether-based solvent, a sulfoxide-based solvent, and a sulfone-based solvent, and non-polar solvents such as a hydrocarbon-based solvent.

[0019] Among the organic solvents, organic solvents containing a plurality of kinds of functional groups that characterize each of the above-described solvents in the structure thereof are also present, but in this case, the organic solvent is considered to correspond to any solvent species containing the functional group of the organic solvent, as described below. For example, diethylene glycol monomethyl ether is considered to correspond to both the alcohol-based solvent and the ether-based solvent in the above-described classification.<<Ketone-based solvent>>

[0020] The ketone-based solvent is an organic solvent containing C-C(=O)-C in the structure thereof.

[0021] Specific examples of the ketone-based solvent include 1-octanone, 2-octanone, 1-nonanone, 2-nonanone, acetone, 4-heptanone, 1-hexanone, 2-hexanone, diisobutyl ketone, phenylacetone, methyl ethyl ketone, methyl isobutyl ketone, ionone, diacetonyl alcohol, acetyl carbinol, acetophenone, methyl naphthyl ketone, and methyl amyl ketone (2-heptanone).

[0022] In addition, the ketone-based solvent may be a cyclic ketone-based solvent. Specific examples of the cyclic ketone-based solvent include cyclohexanone (CH), methylcyclohexanone, isophorone, propylene carbonate, ethylene carbonate, and dihydrolevoglucosenone (Cyrene).<<Ester-based solvent>>

[0023] The ester-based solvent is an organic solvent containing C-C(=O)-O-C in the structure thereof.

[0024] Specific examples of the ester-based solvent include methyl acetate, butyl acetate, ethyl acetate, isopropyl acetate, amyl acetate, isoamyl acetate, ethyl methoxyacetate, ethyl ethoxyacetate, ethylene glycol monoethyl ether acetate, ethylene glycol monopropyl ether acetate, ethylene glycol monobutyl ether acetate, ethylene glycol monophenyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monopropyl ether acetate, diethylene glycol monophenyl ether acetate, diethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate, 2-methoxybutyl acetate, 3-methoxybutyl acetate, 4-methoxybutyl acetate, 3-methyl-3-methoxybutyl acetate, 3-ethyl-3-methoxybutyl acetate, propylene glycol monomethyl ether acetate (PGMEA), propylene glycol monoethyl ether acetate, propylene glycol monopropyl ether acetate, 2-ethoxybutyl acetate, 4-ethoxybutyl acetate, 4-propoxybutyl acetate, 2-methoxypentyl acetate, 3-methoxypentyl acetate, 4-methoxypentyl acetate, 2-methyl-3-methoxypentyl acetate, 3-methyl-3-methoxypentyl acetate, 3-methyl-4-methoxypentyl acetate, 4-methyl-4-methoxypentyl acetate, propylene glycol diacetate, methyl formate, ethyl formate, butyl formate, propyl formate, ethyl lactate, butyl lactate, propyl lactate, ethyl carbonate, propyl carbonate, butyl carbonate, methyl pyruvate, ethyl pyruvate, propyl pyruvate, butyl pyruvate, methyl acetoacetate, ethyl acetoacetate, methyl propionate, ethyl propionate, propyl propionate, isopropyl propionate, methyl 2-hydroxypropionate, ethyl 2-hydroxypropionate, methyl-3-methoxypropionate, ethyl-3-methoxypropionate, ethyl-3-ethoxypropionate, and propyl-3-methoxypropionate.

[0025] In addition, the ester-based solvent may be a cyclic ester-based solvent (lactone-based solvent). Specific examples of the lactone-based solvent include γ-butyrolactone (GBL), ε-caprolactone, γ-valerolactone, and δ-valerolactone.<<Alcohol-based solvent>

[0026] The alcohol-based solvent is an organic solvent containing an alcoholic hydroxy group in the structure thereof.

[0027] The term "alcoholic hydroxy group" denotes a hydroxy group bonded to a carbon atom of an aliphatic hydrocarbon group.

[0028] Specific examples of the alcohol-based solvent include 2-propanol (isopropanol), 1-butanol (n-butanol), 1-hexanol, 1-heptanol, 1-octanol, 2-hexanol, 2-heptanol, 2-octanol, 3-hexanol, 3-heptanol, 3-octanol, 4-octanol, benzyl alcohol, ethylene glycol, diethylene glycol, propylene glycol (PG), and dipropylene glycol.<<Nitrile-based solvent>>

[0029] The nitrile-based solvent is an organic solvent containing a nitrile group in the structure thereof.

[0030] Specific examples of the nitrile-based solvent include acetonitrile, propionitrile, valeronitrile, and butyronitrile.<<Amide-based solvent>>

[0031] The amide-based solvent is an organic solvent containing an amide group in the structure thereof.

[0032] Specific examples of the amide-based solvent include chain-like amide-based solvents such as dimethylacetamide (DMAc), dimethylformamide, and tetramethylurea, and cyclic amide (lactam)-based solvents such as dimethylimidazolidinone, N-methylpyrrolidone, 1-ethyl-2-pyrrolidone, and 1-butyl-2-pyrrolidone.<<Ether-based solvent>>

[0033] The ether-based solvent is an organic solvent containing C-O-C in the structure thereof.

[0034] Specific examples of the ether-based solvent include ethylene glycol monomethyl ether (EGME), ethylene glycol isopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monohexyl ether, propylene glycol monomethyl ether (PGME), propylene glycol monoethyl ether (PGEE), propylene glycol monopropyl ether, propylene glycol monobutyl ether, and diisopropylene glycol monomethyl ether.<<Sulfoxide-based solvent>>

[0035] The sulfoxide-based solvent is an organic solvent containing a sulfinyl group - S(=O)- in the structure thereof.

[0036] Specific examples of the sulfoxide-based solvent include dimethyl sulfoxide (DMSO).<<Sulfone-based solvent>>

[0037] The sulfone-based solvent is an organic solvent containing a sulfonyl group - S(=O) 2 - in the structure thereof.

[0038] Specific examples of the sulfone-based solvent include sulfolane.<<Hydrocarbon-based solvent>>

[0039] The hydrocarbon-based solvent is a hydrocarbon solvent formed of a hydrocarbon which may be halogenated and having no substituent other than a halogen atom. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. Among these, a fluorine atom is preferable.

[0040] Specific examples of the hydrocarbon-based solvent include n-nonane, n-decane, n-undecane, n-dodecane, n-tridecane, n-tetradecane, n-pentadecane, and n-hexadecane.

[0041] Among the examples, the two or more kinds of solvents in the cleaning liquid according to the present embodiment are preferably a mixed solvent of two or more kinds of solvents selected from the group consisting of a ketone-based solvent, an ester-based solvent, an alcohol-based solvent, and an ether-based solvent, more preferably a mixed solvent of two or more kinds of solvents selected from the group consisting of a ketone-based solvent, an ester-based solvent, and an ether-based solvent, and still more preferably a mixed solvent of two or more kinds of solvents selected from the group consisting of an ester-based solvent and an ether-based solvent.

[0042] Further, in the present specification, the two or more kinds of solvents may be two or more kinds of solvents that contain two kinds of compounds and are classified into the same kind. For example, the two or more kinds of solvents may be a mixed solvent of 1-octanone and cyclohexanone, both of which are classified as ketone-based solvents.

[0043] <<Metal remover>>

[0044] Examples of the metal remover contained in the cleaning liquid according to the present embodiment include a metal chelating agent and an organic acid.<<Metal chelating agent>>

[0045] Examples of the metal chelating agent in the present embodiment include an amino carboxylic acid-based chelating agent such as ethylenediaminetetraacetic acid, nitrilotriacetic acid, or diethylenetriaminepentaacetic acid, a phosphonic acid-based chelating agent such as 1-hydroxyethane-1,1-diphosphonic acid or nitrilotris(methylenephosphonic acid), and a compound (A1) represented by General Formula (a-1) (hereinafter, also simply referred to as "compound (A1)"). Among these, the compound (A1) is preferable as the metal chelating agent.

[0046] [In the formula, Ra 1< and Ra 2< each independently represent an alkyl group having 1 to 3 carbon atoms. Ra 3< and Ra 4< each independently represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. Ya 1< and Ya 2< each independently represent a single bond, -O-, -S-, or -N(Ra 5< )-. Ra 5< represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. n represents an integer of 0 to 3.]

[0047] In Formula (a-1), examples of the alkyl group having 1 to 3 carbon atoms as Ra 1< to Ra 5< include a methyl group, an ethyl group, a propyl group, and an isopropyl group.

[0048] In Formula (a-1), Ra 1< and Ra 2< each independently represent preferably a methyl group or an ethyl group and more preferably a methyl group.

[0049] It is preferable that Ra 3< and Ra 4< each represent a hydrogen atom.

[0050] Ya 1< represents preferably a single bond or -O- and more preferably a single bond.

[0051] Ya 2< represents preferably a single bond or -O- and more preferably a single bond.

[0052] n represents preferably 1 or 2 and more preferably 1.

[0053] Among the examples, the compound (A1) is preferably acetylacetone (AcAc) or acetonylacetone and more preferably acetylacetone (AcAc).

[0054] In the cleaning liquid according to the present embodiment, the metal chelating agent may be used alone or in combination of two or more kinds thereof.<<Organic acid>>

[0055] Examples of the organic acid in the present embodiment include a carboxylic acid such as lactic acid (LA), citric acid, malic acid, formic acid, acetic acid, oxalic acid, 2-nitrophenylacetic acid, 2-ethylhexanoic acid, or dodecanoic acid, saccharic acid such as ascorbic acid or glucuronic acid, sulfonic acid such as methanesulfonic acid, benzenesulfonic acid, or p-toluenesulfonic acid, and phosphoric acid ester and phosphoric acid, such as bis(2-ethylhexyl)phosphoric acid.

[0056] Among the examples, the organic acid is preferably a carboxylic acid, more preferably a hydroxy acid, still more preferably at least one selected from the group consisting of lactic acid, citric acid, and malic acid, and particularly preferably lactic acid.

[0057] In the cleaning liquid according to the present embodiment, the organic acid may be used alone or in combination of two or more kinds thereof.

[0058] It is preferable that the cleaning liquid according to the present embodiment contains two or more kinds of the metal removers.

[0059] The cleaning liquid according to the present embodiment contains preferably two or more kinds of metal removers selected from the group consisting of the above-described metal chelating agent and the above-described organic acid, more preferably two or more kinds of metal removers selected from the group consisting of the above-described compound (A1) and the above-described organic acid, and still more preferably two or more kinds of metal removers selected from the group consisting of the above-described compound (A1) and the above-described carboxylic acid.

[0060] In the cleaning liquid according to the present embodiment, among the examples, it is preferable to use the above-described metal chelating agent and the above-described organic acid in combination, more preferable to use the above-described compound (A1) and the above-described organic acid in combination, and still more preferable to use the above-described compound (A1) and the above-described carboxylic acid in combination.<Optional components>

[0061] The cleaning liquid according to the present embodiment may contain optional components other than the above-described solvent and the above-described metal remover within a range where the effects of the present invention are not impaired.

[0062] Examples of the optional components include a pH adjuster and a surfactant.[Distance between Hansen solubility parameters (HSP distance)]

[0063] The cleaning liquid according to the present embodiment contains the above-described two or more kinds of solvents and metal removers, and the distance (HSP distance) between the Hansen solubility parameter of the cleaning liquid and the Hansen solubility parameter of dimethylacetamide (DMAc) is 1.0 or less, preferably 0.8 or less, and more preferably 0.5 or less.

[0064] In a case where the HSP distance of the cleaning liquid according to the present embodiment is less than or equal to the above-described upper limits, the effect of removing impurity stains of the cleaning liquid is enhanced regardless of the material of the cleaning target. The HSP distance of the cleaning liquid according to the present embodiment is preferably as low as possible from the viewpoint of enhancing the effect of removing impurity stains of the cleaning liquid.

[0065] The term "Hansen solubility parameter" in the present specification is a numerical constant that is theoretically calculated and is a useful tool for predicting the ability of a solvent material to dissolve a specific solute.

[0066] The Hansen solubility parameter can be used as a measure of the overall strength and selectivity of a material by combining the following three Hansen solubility parameters (δ d (dispersion force term), δ p (polar term), and δ h (hydrogen bond term)) that are experimentally and theoretically derived. The Hansen solubility parameter is in units of MPa 0.5< or (J / cc) 0.5< . δ d : energy derived from dispersion force between molecules δ p : energy derived from polar force between molecules δ h : energy derived from hydrogen bond force between molecules

[0067] The "Hansen solubility parameter" can be calculated, for example, by Hansen Solubility from "Molecular Modeling Pro" software, version 5.1.9 (ChemSW, Fairfield CA, www.chemsw.com) or Dynacomp Software.

[0068] Since the cleaning liquid according to the present embodiment is a mixture, the Hansen solubility parameter of the cleaning liquid according to the present embodiment can be determined as follows.

[0069] For example, in a case where a cleaning liquid CS formed of a solvent S 1< (δ ds1 , δ ps1 , δ hs1 ), a solvent S 2< (δ ds2 , δ ps2 , δ hs2 ), a metal remover B 1< (δ dB1 , δ pB1 , δ hB1 ), and a metal remover B 2< (δ dB2 , δ pB2 , δ hB2 ) has a blending amount of the solvent S 1< of a, a blending amount of the solvent S 2< of b, a blending amount of the metal remover B 1< of c, and a blending amount of the metal remover B 2< of d, δ dcs (dispersion force term), δ pcs (polar term), and δ hcs (hydrogen bond term) of the cleaning liquid CS are calculated by the following equations. It is noted that a + b + c + d = 100. δ dcs = δ ds 1 × a + δ ds 2 × b + δ dB 1 × c + δ dB 2 × d / 100 δ pcs = δ ps 1 × a + δ ps 2 × b + δ pB 1 × c + δ pB 2 × d / 100 δ hcs = δ hs 1 × a + δ hs 2 × b + δ hB 1 × c + δ hB 2 × d / 100

[0070] The distance (HSP distance) between the Hansen solubility parameter of the cleaning liquid CS (cleaning liquid according to the present embodiment) and the Hansen solubility parameter of dimethylacetamide (DMAc) is calculated by Equation (1). HSP distance = 4 δ dcs − δ dDMAc 2 + δ pcs − δ pDMAc 2 + δ hcs − δ hDMA c 2 0.5

[0071] Further, a value of 16.8 is used for the dispersion force term (δ dDMAc ) of dimethylacetamide, a value of 11.5 is used for the polar term (δ pDMAc ), and a value of 9.4 is used for the hydrogen bond term (δ hDMAc ).

[0072] The HSP distance in the cleaning liquid according to the present embodiment can be controlled, for example, by adopting a solvent or a metal remover close to the values of the dispersion force term (δ dDMAc ), the polar term (δ pDMAc ), and the hydrogen bond term (δ hDMAc ) of dimethylacetamide or by selecting a combination of each component.[Content of metal impurities]

[0073] The content of the metal impurities in the cleaning liquid according to the present embodiment is 0.1 × 10 -9< parts by mass or greater and 10 2< × 10 -6< parts by mass or less, preferably 0.25 × 10 -9< parts by mass or greater and 1 × 10 -6< (1000 × 10 -9< ) parts by mass or less, more preferably 0.5 × 10 -9< parts by mass or greater and 500 × 10 -9< parts by mass or less, still more preferably 0.75 × 10 -9< parts by mass or greater and 100 × 10 -9< parts by mass or less, and particularly preferably 1 × 10 -9< parts by mass or greater and 20 × 10 -9< parts by mass or less with respect to 100 parts by mass of the total amount of the solvents and the metal remover.

[0074] In a case where the content of the metal impurities in the cleaning liquid according to the present embodiment is in the above-described ranges, the effect of removing the impurity stains of the cleaning liquid is further enhanced regardless of the material of the cleaning target.

[0075] The term "metal impurities" contained in the cleaning liquid according to the present embodiment denotes metal components including metal elements selected from the group consisting of Na, Ca, K, Fe, Ti, Al, Ni, Zn, Cr, and Mg.

[0076] The term "content of the metal impurities" denotes the total content of the metal components including metal elements selected from the group consisting of Na, Ca, K, Fe, Ti, Al, Ni, Zn, Cr, and Mg.

[0077] The mass of the metal impurities in the cleaning liquid is determined by inductively coupled plasma mass spectrometry.

[0078] In practice, the content (mass fraction) of the metal impurities in the cleaning liquid is obtained by specifying the metal elements to be measured and measuring the total amount thereof.

[0079] The metal elements to be measured are, for example, 12 to 28 elements, and further include any metal element of Li, V, Mn, Co, Cu, Ge, As, Sr, Zr, Mo, Ag, Cd, Sn, Sb, Ba, W, Au, or Pb in addition to Na, Ca, K, Fe, Ti, Al, Ni, Zn, Cr, and Mg.

[0080] The content of the metal impurities in the cleaning liquid can be adjusted by controlling the amount of the metal impurities contained in the solvent or the metal remover to be blended; or can be adjusted by mixing the solvent, the metal remover, and the optional component and adding a metal element separately from these; or can be adjusted by separating and removing an excess metal element.

[0081] Suitable examples of the cleaning liquid according to the present embodiment include a composition (X) containing a mixed solvent of two or more kinds of solvents selected from the group consisting of a ketone-based solvent, an ester-based solvent, an alcohol-based solvent, and an ether-based solvent, the above-described metal chelating agent, and the above-described organic acid, in which the HSP distance is 1.0 or less, and the content of the metal impurities is 0.1 × 10 -9< parts by mass or greater and 10 2< × 10 -6< parts by mass or less with respect to 100 parts by mass of the total amount of the mixed solvent, the metal chelating agent, and the organic acid.

[0082] The distance (HSP distance) between the Hansen solubility parameter of the composition (X) and the Hansen solubility parameter of DMAc is 1.0 or less, preferably 0.8 or less, more preferably 0.5 or less, still more preferably 0.4 or less, and particularly preferably 0.3 or less, and it is preferable that the distance thereof is as small as possible.

[0083] The mixed solvent in the composition (X) is more preferably a mixed solvent of one or more kinds of solvents selected from the group consisting of a ketone-based solvent and an ester-based solvent (hereinafter, also referred to as "solvent S1") and one or more kinds of solvents selected from the group consisting of an alcohol-based solvent and an ether-based solvent (hereinafter, also referred to as "solvent S2"), still more preferably a mixed solvent of an ester-based solvent and an ether-based solvent, and particularly preferably a mixed solvent of a lactone-based solvent and an ether-based solvent.

[0084] For example, in a case where the two or more kinds of solvents in the composition (X) are a mixed solvent of the solvent S1 and the solvent S2, the mixing ratio of the solvent S1 to the solvent S2 (solvent S1:solvent S2) is preferably 20:80 to 80:20, more preferably 30:70 to 70:30, and still more preferably 40:60 to 60:40 in terms of the mass ratio.

[0085] Examples of a suitable combination of the two or more kinds of solvents in the composition (X) include a mixed solvent of one or more kinds of solvents selected from the group consisting of γ-butyrolactone, ε-caprolactone, and γ-valerolactone and one or more kinds of solvents selected from the group consisting of EGME, PGME, and PGEE, and a mixed solvent of dihydrolevoglucosenone (Cyrene) and PG.

[0086] Among these, as a suitable combination of the two or more kinds of solvents, a mixed solvent of one or more kinds of solvents selected from the group consisting of γ-butyrolactone, ε-caprolactone, and γ-valerolactone and one or more kinds of solvents selected from the group consisting of EGME, PGME, and PGEE is preferable, and a mixed solvent of γ-butyrolactone and PGME is more preferable.

[0087] The metal chelating agent in the composition (X) is preferably a compound (A1) and more preferably acetylacetone (AcAc).

[0088] The organic acid in the composition (X) is preferably a carboxylic acid, more preferably a hydroxy acid, and still more preferably lactic acid.

[0089] The content of the metal impurities in the composition (X) is 0.1 × 10 -9< parts by mass or greater and 10 2< × 10 -6< parts by mass or less, preferably 0.25 × 10 -9< parts by mass or greater and 1 × 10 -6< (1000 × 10 -9< ) parts by mass or less, more preferably 0.5 × 10 -9< parts by mass or greater and 500 × 10 -9< parts by mass or less, still more preferably 0.75 × 10 -9< parts by mass or greater and 100 × 10 -9< parts by mass or less, and particularly preferably 1 × 10 -9< parts by mass or greater and 20 × 10 -9< parts by mass or less with respect to 100 parts by mass of the total amount of the mixed solvent, the metal chelating agent, and the organic acid.

[0090] The content of each of the mixed solvent, the metal chelating agent, and the organic acid in the composition (X) is appropriately selected such that the HSP distance reaches 1.0 or less.

[0091] The content of the mixed solvent in the composition (X) is preferably 90% to 99.5% by mass and more preferably 95% to 99% by mass with respect to the total amount of the composition (X).

[0092] The content of the metal chelating agent in the composition (X) is preferably 0.1% to 9% by mass, more preferably 0.5% to 9% by mass, and still more preferably 0.5% to 5% by mass with respect to the total amount of the composition (X).

[0093] The proportion of the compound (A1) in the metal chelating agent is preferably 50% by mass or more and more preferably 75% by mass or more, and may be 100% by mass with respect to the total mass of the metal chelating agent.

[0094] The content of the organic acid in the composition (X) is preferably 0.1% to 9% by mass, more preferably 0.5% to 9% by mass, and still more preferably 0.5% to 5% by mass with respect to 100% by mass of the total amount of the composition (X).

[0095] The proportion of the carboxylic acid in the organic acid is preferably 50% by mass or greater and more preferably 75% by mass or greater, and may be 100% by mass with respect to the total mass of the organic acid.

[0096] The composition (X) may further contain the optional components described above as necessary, in addition to the mixed solvent, the metal chelating agent, and the organic acid.

[0097] The cleaning liquid of the present embodiment is a cleaning liquid useful for cleaning a membrane.

[0098] The form and the shape of the membrane are not particularly limited, and examples thereof include a flat membrane, a hollow fiber membrane, a tubular membrane, a spiral membrane, and a thin membrane (film).

[0099] In addition, the material of the membrane is not particularly limited, and examples thereof include polyolefin (polyethylene, polypropylene, or the like), polysulfone, polyacrylonitrile, polyamide, polyimide, polyvinyl alcohol, a cellulose acetate-based material, a fluoropolymer, and ceramic.

[0100] In addition, the cleaning liquid of the present embodiment is also useful for removing impurity stains from various cleaning targets. Examples of the various cleaning targets include each pipe in a production line, a container to be used, and an instrument. For example, the cleaning liquid of the present embodiment can be used for cleaning a cleaning target selected from the group consisting of a metal pipe, a resin pipe, a glass pipe, a metal joint, a resin joint, a glass joint, a filter, a chemical liquid container, a measurement cell, and a chromatography column.

[0101] The cleaning liquid of the present embodiment described above contains two or more kinds of solvents and a metal remover. In addition, the distance (HSP distance) between the Hansen solubility parameter of the cleaning liquid and the Hansen solubility parameter of dimethylacetamide (DMAc) is 1.0 or less, and the content of the metal impurities is 0.1 × 10 -9< parts by mass or greater and 10 2< × 10 -6< parts by mass or less with respect to 100 parts by mass of the total amount of the solvents and the metal remover.

[0102] The reason is not clear, but a satisfactory cleaning and removing effect is exhibited even with respect to both a polar cleaning target and a non-polar cleaning target in a case where such a cleaning liquid contains a metal remover while the Hansen solubility parameter of the entire cleaning liquid is adjusted to be close to that of DMAc. In addition, since the cleaning liquid contains a metal remover, the removability of metal impurity stains is excellent.

[0103] Further, such a cleaning liquid is intentionally made to contain a specific content of metal impurities. In this manner, the effect of removing impurity stains from various cleaning targets is further enhanced, and particularly, the effect of removing metal impurity stains is greatly enhanced.(Second aspect: cleaning method)

[0104] According to an embodiment, the cleaning method is a method of cleaning a cleaning target by bringing the above-described cleaning liquid into contact with the cleaning target.

[0105] Examples of the cleaning target in the cleaning method of the present embodiment include a membrane, each pipe in a production line, a container to be used, and an instrument. For example, the cleaning target may be a membrane such as a flat membrane, a hollow fiber membrane, a tubular membrane, a spiral membrane, or a thin membrane (film). Alternatively, the cleaning target may be selected from the group consisting of a metal pipe, a resin pipe, a glass pipe, a metal joint, a resin joint, a glass joint, a filter, a chemical liquid container, a measurement cell, and a chromatography column.

[0106] More specific examples of a cleaning operation of cleaning the cleaning target by bringing the above-described cleaning liquid into contact with the cleaning target include a method of immersing a cleaning target in the cleaning liquid and a method of spraying the cleaning liquid onto a cleaning target.

[0107] The cleaning operation may be performed only once or a plurality of times.

[0108] In addition, the cleaning liquid may be heated or the cleaning operation may be performed at room temperature (for example, 23°C) during the cleaning operation.

[0109] The cleaning method of the present embodiment may include a drying step of drying the cleaning target cleaned by the above-described cleaning operation. A known method such as a method of air drying at room temperature, a method of placing the cleaned cleaning target in a constant-temperature tank and heating the cleaning target, or a method of vacuum drying can be applied in the drying step.

[0110] According to the cleaning method of the present embodiment described above, since the above-described cleaning liquid is used, the cleaning method has excellent stain removability for organic impurities or metal impurities from various cleaning targets.

[0111] The cleaning method according to another embodiment is a method further including, before or after a step of cleaning the cleaning target by bringing the above-described cleaning liquid into contact with the cleaning target (hereinafter, also referred to as "cleaning step A"), a step of cleaning the cleaning target by bringing the cleaning target into contact with a second cleaning liquid different from the cleaning liquid (hereinafter, also referred to as "cleaning step B").

[0112] The cleaning method according to another embodiment described above may include (i) a step of cleaning the cleaning target by bringing the second cleaning liquid different from the above-described cleaning liquid (referred to as a first cleaning liquid) into contact with the cleaning target and a step of cleaning the cleaning target by bringing the first cleaning liquid into contact with the cleaning target cleaned with the second cleaning liquid, (ii) a step of cleaning the cleaning target by bringing the above-described cleaning liquid (first cleaning liquid) into contact with the cleaning target and a step of cleaning the cleaning target by bringing the second cleaning liquid different from the first cleaning liquid into contact with the cleaning target cleaned with the first cleaning liquid, or (iii) a step of cleaning the cleaning target by bringing the second cleaning liquid different from the above-described cleaning liquid (first cleaning liquid) into contact with the cleaning target, a step of cleaning the cleaning target by bringing the first cleaning liquid into contact with the cleaning target cleaned with the second cleaning liquid, and a step of cleaning the cleaning target by bringing a third cleaning liquid different from the first cleaning liquid into contact with the cleaning target cleaned with the first cleaning liquid.

[0113] In the item (iii), the second cleaning liquid and the third cleaning liquid may be the same as or different from each other.· Cleaning step B

[0114] Examples of the method of cleaning the cleaning target by bringing the second cleaning liquid different from the above-described cleaning liquid in the cleaning step B into contact with the cleaning target include the same method as the method in the above-described cleaning step A (a method of immersing the cleaning target in the cleaning liquid, a method of spraying the cleaning liquid onto the cleaning target, or the like).

[0115] The cleaning step B may be performed only once or a plurality of times before or after the cleaning step A.· Second cleaning liquid and third cleaning liquid

[0116] Examples of the cleaning liquid (the second cleaning liquid or the third cleaning liquid) different from the above-described cleaning liquid include a cleaning liquid containing a solvent and no metal remover. Typical examples of the cleaning liquid (the second cleaning liquid or the third cleaning liquid) include a cleaning liquid formed of only a solvent.

[0117] Examples of the solvent in the cleaning liquid (the second cleaning liquid or the third cleaning liquid) include polar solvents such as a ketone-based solvent, an ester-based solvent, an alcohol-based solvent, a nitrile-based solvent, an amide-based solvent, an ether-based solvent, a sulfoxide-based solvent, and a sulfone-based solvent, and non-polar solvents such as a hydrocarbon-based solvent, and specific examples thereof include the same solvents as those in the above-described cleaning liquid.

[0118] Among these, the cleaning liquid (the second cleaning liquid or the third cleaning liquid) contains preferably an alcohol-based solvent, more preferably an alcohol-based solvent having 1 to 5 carbon atoms, and still more preferably 2-propanol (isopropanol).

[0119] According to another embodiment of the cleaning method, a method including the cleaning step A and a step of cleaning the cleaning target by bringing the cleaning target into contact with an alcohol-based solvent (preferably 2-propanol) before or after the cleaning step A is suitable.

[0120] According to another embodiment, the cleaning method may further include a drying step of drying the cleaning target cleaned in the cleaning step A or the cleaning step B.

[0121] A known method such as a method of air drying at room temperature, a method of placing the cleaned cleaning target in a constant-temperature tank and heating the cleaning target, or a method of vacuum drying can be applied in the drying step.

[0122] According to another embodiment of the cleaning method described above, since the cleaning method further includes the cleaning step B in addition to the cleaning step A described above, the effect of removing impurity stains adhering to the cleaning target is further enhanced as compared with the cleaning method including only the cleaning step A described above.Examples

[0123] Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.<Preparation of cleaning liquid>

[0124] Each component was mixed according to the composition listed in Table 1 to prepare a cleaning liquid of each example.(Example 1)

[0125] In a cleaning liquid of Example 1, the content of metal impurities after mixing each component was 1.1 × 10 -9< parts by mass in total of 28 elements of metal elements with respect to 100 parts by mass of the total amount of the solvent and the metal remover, as a result of [Measurement of content of metal impurities] described below.(Examples 2 and 3)

[0126] A cleaning liquid of Example 2 in which the content of metal impurities was 4.5 × 10 -9< parts by mass and a cleaning liquid of Example 3 in which the content of metal impurities was 23.9 × 10 -9< parts by mass with respect to 100 parts by mass of the total amount of the solvent and the metal remover were prepared by adding a standard solution for metal analysis in a solvent (manufactured by Agilent Technologies, Inc., part number: 5190-8715) as a mineral oil to the cleaning liquid of Example 1.(Comparative Examples 1 and 2)

[0127] As a cleaning liquid of Comparative Example 1, OK73 thinner was used. The composition of the OK73 thinner was a mixed solvent of PGMEA and PGME at a mass ratio of 30:70.

[0128] As a cleaning liquid of Comparative Example 2, isopropanol was used. The content of metal impurities in the isopropanol was set to 2.5 × 10 -9< parts by mass with respect to 100 parts by mass of the total amount of the solvent and the metal remover. [Table 1]Cleaning liquidSolventMetal removerHSP distanceProportion of metal impurities with respect to 100 parts by mass of total amount of solvent and metal remover (parts by mass)Comparative Example 1PGMEA

[30] PGME

[70] --6.150Example 1GBL

[49] PGME

[49] AcAc [1]LA [1]0.271.1 × 10 -9< Example 2GBL

[49] PGME

[49] AcAc [1]LA [1]0.274.5 × 10 -9< Example 3GBL

[49] PGME

[49] AcAc [1]LA [1]0.2723.9 × 10 -9< Comparative Example 2IPA

[100] ---5.612.5 × 10 -9<

[0129] The abbreviations in the table represent the following compounds. The numerical values in the brackets in the table are blending amounts (parts by mass). GBL: γ-butyrolactone PGME: propylene glycol monomethyl ether PGMEA: propylene glycol monomethyl ether acetate AcAc: acetylacetone LA: lactic acid IPA: isopropanol [Calculation of HSP distance]

[0130] The Hansen solubility parameter of each component of the cleaning liquid was calculated using "Molecular Modeling Pro" software, version 5.1.9 (ChemSW, Fairfield CA, www.chemsw.com). The Hansen solubility parameter of each component is shown below.

[0131] A value of 18 was used as the dispersion force term (δ dGBL ) of GBL, a value of 16.6 was used as the polar term (δ pGBL ) of GBL, and a value of 7.4 was used as the hydrogen bond term (δ hGBL ) of GBL.

[0132] A value of 15.6 was used as the dispersion force term (δ dPGME ) of PGME, a value of 6.3 was used as the polar term (δ pPGME ) of PGME, and a value of 11.6 was used as the hydrogen bond term (δ hPGME ) of PGME.

[0133] A value of 16.1 was used as the dispersion force term (δ dAcAc ) of AcAc, a value of 10 was used as the polar term (δ pAcAc ) of AcAc, and a value of 6.2 was used as the hydrogen bond term (δ hAcAc ) of AcAc.

[0134] A value of 17 was used as the dispersion force term (δ dLA ) of LA, a value of 8.3 was used as the polar term (δ pLA ) of LA, and a value of 28.4 was used as the hydrogen bond term (δ hLA ) of LA.

[0135] A value of 15.6 was used as the dispersion force term (δ dPGMEA ) of PGMEA, a value of 6.3 was used as the polar term (δ pPGMEA ) of PGMEA, and a value of 7.7 was used as the hydrogen bond term (δ hPGMEA ) of PGMEA.

[0136] A value of 16.3 was used as the dispersion force term (δ dIPA ) of IPA, a value of 6.8 was used as the polar term (δ pIPA ) of IPA, and a value of 6.5 was used as the hydrogen bond term (δ hIPA ) of IPA.

[0137] The dispersion force terms (δ dt ), the polar terms (δ pt ), and the hydrogen bond terms (δ ht ) of the cleaning liquids of Examples 1 to 3 were obtained as follows. δ dt = δ dGBL × 49 + δ dPGME × 49 + δ dAcAc × 1 + δ dLA × 1 / 100 δ pt = δ pGBL × 49 + δ pPGME × 49 + δ dAcAc × 1 + δ dLA × 1 / 100 δ ht = δ hGBL × 49 + δ hPGME × 49 + δ dAcAc × 1 + δ dLA × 1 / 100

[0138] The dispersion force term (δ dt ), the polar term (δ pt ), and the hydrogen bond term (δ ht ) of the cleaning liquid of Comparative Example 1 were determined as follows. δ dt = δ dPGMEA × 30 + δ dPGME × 70 / 100 δ pt = δ pPGMEA × 30 + δ pPGME × 70 / 100 δ ht = δ hPGMEA × 30 + δ hPGME × 70 / 100

[0139] The dispersion force term (δ dt ), the polar term (δ pt ), and the hydrogen bond term (δ ht ) of the cleaning liquid of Comparative Example 2 were determined as follows. δ dt = δ dIPA × 100 / 100 δ pt = δ pIPA × 100 / 100 δ ht = δ hIPA × 100 / 100

[0140] In Examples 1 to 3, the distance (HSP distance) between the Hansen solubility parameter (MPa 0.5< ) of the cleaning liquid and the Hansen solubility parameter (MPa 0.5< ) of dimethylacetamide was calculated according to Equation (1t).

[0141] A value of 16.8 was used as the dispersion force term (δ dDMAc ) of dimethylacetamide, a value of 11.5 was used as the polar term (δ pDMAc ), and a value of 9.4 was used as the hydrogen bond term (δ hDMAc ). HSP distance = 4 δ dt − δ dDMAc 2 + δ dp − δ pDMAc 2 + δ ht − δ hDMAc 2 0.5

[0142] In Comparative Examples 1 and 2, the distance (HSP distance) between the Hansen solubility parameter (MPa 0.5< ) of the cleaning liquid and the Hansen solubility parameter (MPa 0.5< ) of dimethylacetamide was also calculated in the same manner as in Examples 1 to 3.[Measurement of content of metal impurities]

[0143] The content of the metal impurities in the cleaning liquid was measured using an inductively coupled plasma mass spectrometer (trade name: ICP-MS 8900, manufactured by Agilent Technologies, Inc.).

[0144] The measured metal elements were 28 elements of Na, Ca, K, Fe, Ti, Al, Ni, Zn, Cr, Mg, Li, V, Mn, Co, Cu, Ge, As, Sr, Zr, Mo, Ag, Cd, Sn, Sb, Ba, W, Au, and Pb, and the total amount thereof was defined as the content (mass fraction) of the metal impurities in the cleaning liquid.

[0145] The metal impurity stains in the cleaning evaluation described below, that is, the total metal amount in the OK73 thinner was also measured in the same manner as described above.<Cleaning evaluation (1)>

[0146] The removability of the metal impurity stains was evaluated by the cleaning method described below using the cleaning liquid of each example with respect to a porous polyethylene film serving as a cleaning target. The results thereof are listed in Table 2.(Comparative Example 1-1)

[0147] 100 mL of the cleaning liquid (OK73 thinner) of Comparative Example 1 was added to a container.

[0148] A porous polyethylene film with a size of 1000 cm 2< was placed in the container and immersed for 1 day.

[0149] Thereafter, the porous polyethylene film was taken out, and the total metal amount in the OK73 thinner was measured, which was 37.4 ppb.(Example 1-1)

[0150] 100 mL of the cleaning liquid of Example 1 was added to a container.

[0151] A porous polyethylene film with a size of 1000 cm 2< was placed in the container and immersed for 1 day.

[0152] Thereafter, the cleaning liquid was discarded from the container, isopropanol (content of metal impurities: 2.5 ppb) was added thereto, and the porous polyethylene film was rinsed.

[0153] After the rinsing, the isopropanol was discarded from the container and replaced with 100 mL of the OK73 thinner (cleaning liquid of Comparative Example 1), and the porous polyethylene film was immersed in the OK73 thinner for 1 day.

[0154] Thereafter, the porous polyethylene film was taken out, and the total metal amount in the OK73 thinner was measured, which was 0.6 ppb.(Examples 1-2 and 1-3)

[0155] The removability of the metal impurity stains from the cleaning target was evaluated by using the above-described cleaning method in the same manner as described above except that the cleaning liquid of Example 1 was changed to each of the cleaning liquids of Examples 2 and 3.

[0156] In a case where the cleaning liquid of Example 2 was used, the total metal amount in the OK73 thinner was 0.1 ppb.

[0157] In a case where the cleaning liquid of Example 3 was used, the total metal amount in the OK73 thinner was 2.1 ppb.(Comparative Example 1-2)

[0158] 100 mL of the cleaning liquid of Comparative Example 2 was added to a container.

[0159] A porous polyethylene film with a size of 1000 cm 2< was placed in the container and immersed for 1 day.

[0160] Thereafter, the cleaning liquid was discarded from the container, isopropanol (content of metal impurities: 2.5 ppb) was added thereto, and the porous polyethylene film was rinsed.

[0161] After the rinsing, the isopropanol was discarded from the container and replaced with 100 mL of the OK73 thinner (cleaning liquid of Comparative Example 1), and the porous polyethylene film was immersed in the OK73 thinner for 1 day.

[0162] Thereafter, the porous polyethylene film was taken out, and the total metal amount in the OK73 thinner was measured, which was 15.7 ppb. [Table 2]Total metal amount (ppb)Comparative Example 1-137.4Example 1-10.6Example 1-20.1Example 1-32.1Comparative Example 1-215.7

[0163] As shown in the results listed in Table 2, it can be confirmed that, in a case where the cleaning liquids of Examples 1 to 3 were used, the total metal amounts were smaller than those in a case where the cleaning liquids of Comparative Examples 1 and 2 were used, and thus, according to the cleaning liquid and the cleaning method to which the present invention was applied, the effect of removing the metal impurity stains from the cleaning target was greatly enhanced.<Cleaning evaluation (2)>

[0164] The removability of the impurity stains was evaluated based on the number of defects on the wafer surface as an index by the cleaning method described below using the cleaning liquid of each example with respect to a chemical liquid supply line (HDPE 2 nm filter connection, pipe) serving as a cleaning target. The results thereof are listed in Table 3.(Comparative Example 2-1)

[0165] An HDPE 2 nm filter (manufactured by Pall Corporation) was connected to the chemical liquid supply line of a resist chemical liquid coating and developing device (Lithius ProZ, manufactured by Tokyo Electron Limited), and 3 GAL of the cleaning liquid (OK73 thinner) of Comparative Example 1 was allowed to pass through the filter.

[0166] A 12-inch wafer was coated with the OK73 thinner allowed to pass through the HDPE 2 nm filter and baked at 80°C for 60 seconds. Thereafter, the number of defects having a size of 17 nm or greater was measured by a wafer surface defect device (Surf Scan SP5 XP, manufactured by KLA Tencor), and the number of defects in a case where only the OK73 thinner was allowed to pass through the filter was 584.(Example 2-1)

[0167] An HDPE 2 nm filter (manufactured by Pall Corporation) was connected to the chemical liquid supply line of a resist chemical liquid coating and developing device (Lithius ProZ, manufactured by Tokyo Electron Limited), 1 GAL of the cleaning liquid of Example 1 was allowed to pass through the filter, the cleaning liquid was switched to the OK73 thinner, and 2 GAL of the OK73 thinner was allowed to pass through the filter.

[0168] A 12-inch wafer was coated with the OK73 thinner, which had been allowed to pass through the HDPE 2 nm filter, and baked at 80°C for 60 seconds. Thereafter, the number of defects having a size of 17 nm or greater was measured by the wafer surface defect device, and the number of defects of the OK73 thinner in a case where only the OK73 thinner was allowed to pass through the filter was 359, but was reduced to 44.(Example 2-2)

[0169] The cleaning liquid of Example 1 was changed to the cleaning liquid of Example 2, the cleaning liquid of Example 2 was allowed to pass through the chemical liquid supply line, 1 L of the cleaning liquid of Example 2 was allowed to pass through after immersion in the chemical liquid supply line for 1 day, and switched to the OK73 thinner, and 1 L of the OK73 thinner was allowed to pass through.

[0170] A 12-inch wafer was coated with the OK73 thinner, which had been allowed to pass through, and baked at 80°C for 60 seconds. Thereafter, the number of defects having a size of 17 nm or greater was measured by the wafer surface defect device, and the number of defects was reduced to 53.(Example 2-3)

[0171] The cleaning liquid of Example 1 was changed to the cleaning liquid of Example 3, the cleaning liquid of Example 3 was allowed to pass through the chemical liquid supply line, 1 L of the cleaning liquid of Example 3 was allowed to pass through after immersion in the chemical liquid supply line for 1 day, and switched to the OK73 thinner, and 1 L of the OK73 thinner was allowed to pass through.

[0172] A 12-inch wafer was coated with the OK73 thinner, which had been allowed to pass through, and baked at 80°C for 60 seconds. Thereafter, the number of defects having a size of 17 nm or greater was measured by the wafer surface defect device, and the number of defects was reduced to 47. [Table 3]Number of defects on wafer surface (pieces)Comparative Example 2-1584Example 2-144Example 2-253Example 2-347

[0173] As shown in the results listed in Table 3, it can be confirmed that, in a case where the cleaning liquids of Examples 1 to 3 were used, the number of defects on the wafer surface was reduced as compared with a case where only the cleaning liquid of Comparative Example 1 was used, and thus the effect of removing impurity stains from the cleaning target could be enhanced by applying the present invention.

[0174] Hereinbefore, preferred examples of the present invention have been described, but the present invention is not limited to these examples. Configurations can be added, omitted, and replaced, and other modifications can be made within a range not departing from the gist of the present invention. The present invention is not limited by the description above, but only by the scope of the appended claims.

Examples

example 1

(Example 1)

[0125]In a cleaning liquid of Example 1, the content of metal impurities after mixing each component was 1.1 × 10 -9< parts by mass in total of 28 elements of metal elements with respect to 100 parts by mass of the total amount of the solvent and the metal remover, as a result of [Measurement of content of metal impurities] described below.

examples 2 and 3

(Examples 2 and 3)

[0126]A cleaning liquid of Example 2 in which the content of metal impurities was 4.5 × 10 -9< parts by mass and a cleaning liquid of Example 3 in which the content of metal impurities was 23.9 × 10 -9< parts by mass with respect to 100 parts by mass of the total amount of the solvent and the metal remover were prepared by adding a standard solution for metal analysis in a solvent (manufactured by Agilent Technologies, Inc., part number: 5190-8715) as a mineral oil to the cleaning liquid of Example 1.

(Comparative Examples 1 and 2)

[0127]As a cleaning liquid of Comparative Example 1, OK73 thinner was used. The composition of the OK73 thinner was a mixed solvent of PGMEA and PGME at a mass ratio of 30:70.

[0128]As a cleaning liquid of Comparative Example 2, isopropanol was used. The content of metal impurities in the isopropanol was set to 2.5 × 10 -9

[Table 1]

Cleaning liquidSolventMetal removerHSP distanceProportion of metal impurities with respect to 100 parts by ma...

example 1-1

(Example 1-1)

[0150]100 mL of the cleaning liquid of Example 1 was added to a container.

[0151]A porous polyethylene film with a size of 1000 cm 2< was placed in the container and immersed for 1 day.

[0152]Thereafter, the cleaning liquid was discarded from the container, isopropanol (content of metal impurities: 2.5 ppb) was added thereto, and the porous polyethylene film was rinsed.

[0153]After the rinsing, the isopropanol was discarded from the container and replaced with 100 mL of the OK73 thinner (cleaning liquid of Comparative Example 1), and the porous polyethylene film was immersed in the OK73 thinner for 1 day.

[0154]Thereafter, the porous polyethylene film was taken out, and the total metal amount in the OK73 thinner was measured, which was 0.6 ppb.

(Examples 1-2 and 1-3)

[0155]The removability of the metal impurity stains from the cleaning target was evaluated by using the above-described cleaning method in the same manner as described above except that the cleaning liquid of Ex...

Claims

1. A cleaning liquid comprising: a solvent; and a metal remover, wherein the cleaning liquid contains two or more kinds of solvents, a distance (HSP distance) between a Hansen solubility parameter of the cleaning liquid and a Hansen solubility parameter of dimethylacetamide is 1.0 or less, and a content of a metal impurity is 0.1 × 10-9 parts by mass or greater and 102 × 10-6 parts by mass or less with respect to 100 parts by mass of a total amount of the solvents and the metal remover.

2. The cleaning liquid according to Claim 1, wherein the metal impurity includes at least one metal element selected from the group consisting of Na, Ca, K, Fe, Ti, Al, Ni, Zn, Cr, and Mg.

3. The cleaning liquid according to Claim 1, wherein the distance (HSP distance) is 0.5 or less.

4. The cleaning liquid according to Claim 1, wherein the cleaning liquid contains two or more kinds of the metal removers.

5. The cleaning liquid according to Claim 1, wherein the metal remover contains an organic acid.

6. The cleaning liquid according to Claim 5, wherein the organic acid is a carboxylic acid.

7. The cleaning liquid according to Claim 1, wherein the cleaning liquid is used for cleaning a cleaning target selected from the group consisting of a metal pipe, a resin pipe, a glass pipe, a metal joint, a resin joint, a glass joint, a filter, a chemical liquid container, a measurement cell, and a chromatography column.

8. A cleaning method comprising: cleaning a cleaning target by bringing the cleaning liquid according to any one of Claims 1 to 7 into contact with the cleaning target.

9. The cleaning method according to Claim 8, wherein the cleaning target is selected from the group consisting of a metal pipe, a resin pipe, a glass pipe, a metal joint, a resin joint, a glass joint, a filter, a chemical liquid container, a measurement cell, and a chromatography column.

10. The cleaning method according to Claim 8, further comprising: a step of cleaning the cleaning target by bringing the cleaning target into contact with a second cleaning liquid different from the cleaning liquid before or after the step of cleaning the cleaning target by bringing the cleaning liquid according to any one of Claims 1 to 7 into contact with the cleaning target.

11. The cleaning method according to Claim 10, wherein the second cleaning liquid contains an alcohol-based solvent.

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