Methacrylic acid-containing composition, method for producing methacrylic acid ester, polymerizable composition, and method for producing methacrylic acid polymer

Abstract

The purpose of the present invention is to provide a methacrylic acid-containing composition having high quality stability during storage. An example composition containing methacrylic acid contains methacrylic acid, a compound represented by formula (11) (component A1), and a polymerization inhibitor (component B), and the concentration of methacrylic acid is 98.00-99.99 mass%. R1a, R2a, R3a, R4a, R5a and R6a are hydrogen atoms, alkyl groups, alkenyl groups, aryl groups, hydroxyl groups, alkoxy groups, amino groups, monovalent groups containing carbonyl groups, alkylthio groups or arylthio groups. And two or more of R1a, R2a, R3a, R4a, and R5a are groups other than hydrogen atoms. R7a represents a hydrogen atom, an alkenyl group, an aryl group, a hydroxyl group, an alkoxy group, an amino group, a monovalent group containing a carbonyl group, an alkylthio group, or an arylthio group. # imgabs0 #

Description

Technical Field

[0001] The present invention relates to a composition containing methacrylic acid, a method for producing a methacrylic acid ester, a polymerizable composition, and a method for producing a methacrylic acid polymer.

[0002] This application claims priority based on Japanese Patent Application Nos. 2022-172927, 2022-172928, 2022-173123, 2022-173124, 2022-173222, and 2022-173223 filed with the Japan Patent Office on October 28, 2022, and the contents of which are incorporated herein by reference. Background Art

[0003] It is known that methacrylic acid (hereinafter also referred to as "MAA") is an extremely useful substance used as a raw material for industrially important methacrylates and polymers of various uses and types. For example, polymethyl methacrylate, which is a homopolymer of methyl methacrylate, is used for signboards, lighting equipment, automobile parts, building-related materials, light guide plates for flat panel displays, light diffusion plates, etc., due to its excellent transparency and weather resistance. In addition, copolymers of methacrylic acid and other monomers are used in coatings, adhesives, fiber treatment agents, resin modifiers, rubber modifiers, leather treatment agents, paper processing agents, lubricating oil additives, cement admixtures, concrete admixtures, latex, photosensitive resins, ion exchange resins, water treatment polymers, etc. Various methods for industrially manufacturing methacrylic acid have been developed, for example, as a by-product of the acetone cyanohydrin (ACH) method and as an intermediate of the C4 direct oxidation method (Non-Patent Document 1). In these manufacturing methods, in order to remove unreacted raw materials, by-products, etc. contained in the generated methacrylic acid, purification such as distillation and crystallization is performed to obtain methacrylic acid of a quality suitable for the target use.

[0004] It is known that since methacrylic acid has the property of being easily polymerized, a polymerization inhibitor is added during the production and storage of methacrylic acid to maintain the quality of methacrylic acid (Non-Patent Document 2). For example, Patent Document 1 states that methyl ether of hydroquinone (MEHQ) is particularly preferred among various polymerization inhibitors. Patent Document 2 states that phenothiazine and hydroquinone are added as polymerization inhibitors to a substance containing methacrylic acid. Patent Document 3 states that methacrylic acid is distilled in the presence of 4-methoxyphenol as a polymerization inhibitor. Patent Document 4 states that a diphenylamine derivative is used as a polymerization inhibitor. Patent Document 5 states that a benzenetriamine derivative is used as a polymerization inhibitor.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2004-155757

[0008] Patent Document 2: Japanese Patent Application Publication No. 2001-072639

[0009] Patent Document 3: Japanese Patent Application Publication No. 2008-101013

[0010] Patent Document 4: Japanese Patent Application No. 2002-533309

[0011] Patent Document 5: Japanese Patent Application No. 2002-513034

[0012] Non-patent literature

[0013] Non-patent document 1: Kuroda Toru, "Development of a catalyst for the production of methyl methacrylate", Catalysts, The Japanese Society of Catalysis, 2003, Vol. 45, No. 5, pp. 366-371

[0014] Non-patent document 2: Otsu Takayuki, "Function of polymerization inhibitors", Organic Synthetic Chemistry, The Society of Organic Synthetic Chemistry, 1975, Vol. 33, No. 8, pp. 634-640 Summary of the invention

[0015] However, even when the above-mentioned polymerization inhibitor is added, the quality of methacrylic acid may deteriorate during storage. Therefore, the present invention provides a composition containing methacrylic acid having high quality stability during storage.

[0016] The present inventors have conducted intensive studies to achieve the above-mentioned object and have found that the quality stability during storage is improved and the decomposition of the polymerization inhibitor is suppressed by the composition containing methacrylic acid containing a compound of a specific structure, thereby completing the present invention.

[0017] According to one embodiment of the present invention, the following methacrylic acid-containing composition is provided.

[0018] A composition containing methacrylic acid, comprising:

[0019] Methacrylic acid, and

[0020] at least one selected from the group consisting of a compound represented by the following formula (11), namely component A1; a compound represented by the following formula (21), namely component A21; a compound represented by the following formula (31), namely component A3; a compound represented by the following formula (41), namely component A4; a compound represented by the following formula (51), namely component A5; and a compound represented by the following formula (61), namely component A6;

[0021] Furthermore, the component B as a polymerization inhibitor may be optionally contained as required.

[0022] The concentration of methacrylic acid is 98.00 to 99.99% by mass.

[0023]

[0024] In formula (11),

[0025] R 1a , R 2a , R 3a , R 4a , R 5a and R 6a each independently represents a hydrogen atom, an alkyl group, an alkenyl group, a hydroxyl group, an alkoxy group, an amino group, a monovalent group containing a carbonyl group, an alkylthio group or an arylthio group,

[0026] R 1a , R 2a , R 3a , R 4a and R 5a Two or more of them are groups other than hydrogen atoms,

[0027] R 7a It represents a hydrogen atom, an alkenyl group, an aryl group, a hydroxyl group, an alkoxy group, an amino group, a monovalent group including a carbonyl group, an alkylthio group, or an arylthio group.

[0028]

[0029] In formula (21),

[0030] R 1b , R 2b , R 3b and R 4b Each independently represents a hydrogen atom, an alkyl group, an alkenyl group, an aryl group, a hydroxyl group, an alkoxy group, an amino group, a monovalent group including a carbonyl group, an alkylthio group or an arylthio group.

[0031]

[0032] In formula (31),

[0033] R 1c , R 2c , R 3c , R 4c , R 5c , R 6c and R 7c Each of the groups independently represents a hydrogen atom, an alkyl group, an alkenyl group, an aryl group, a hydroxyl group, an alkoxy group, an amino group, a monovalent group including a carbonyl group, an alkylthio group or an arylthio group.

[0034] R d -C≡N…(41)

[0035] In formula (41),

[0036] R d It represents an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, or an aryl group having 1 to 12 carbon atoms, and these groups may further have a substituent.

[0037]

[0038] In formula (51),

[0039] R 1e and R 2e each independently represents a hydrogen atom, an alkyl group, an alkenyl group, an aryl group, a hydroxyl group, an alkoxy group, an alkylthio group or an arylthio group,

[0040] R 3e represents a hydrogen atom, an alkyl group, an alkenyl group, an aryl group, a hydroxyl group, an alkoxy group, an amino group, an alkylthio group or an arylthio group,

[0041] R 1e With R 2e , R 2e With R 3e , R 3e With R 1e They may be connected to each other to form a ring.

[0042] Among them, R 1e With R 2e The total number of carbon atoms is 2 or more.

[0043]

[0044] In formula (61),

[0045] R 1f , R 2f and R 3f each independently represents a hydrogen atom, an alkyl group, an alkenyl group, an aryl group, a hydroxyl group, an alkoxy group, an amino group, an alkylthio group or an arylthio group,

[0046] R 4f It represents an alkyl group, an alkenyl group, an aryl group, a hydroxyl group, an alkoxy group, an amino group, a monovalent group including a carbonyl group, an alkylthio group, or an arylthio group.

[0047] Among them, R is not included 1f =H, R 2f =H, R 3f =CH 3 And R 4f =OH is the case where the component A6 is methacrylic acid. 1f , R 2f and R 3fThe total number of carbon atoms is greater than or equal to 1. H represents a hydrogen atom, C represents a carbon atom, and O represents an oxygen atom.

[0048] According to another aspect of the present invention, there is provided a method for producing a methacrylic acid ester, the method comprising the step of esterifying methacrylic acid in the methacrylic acid-containing composition.

[0049] According to another aspect of the present invention, there is provided a polymerizable composition including the above-mentioned methacrylic acid-containing composition.

[0050] According to another aspect of the present invention, there is provided a method for producing a methacrylic acid polymer, the method comprising the step of polymerizing the polymerizable composition.

[0051] According to the present invention, it is possible to provide a methacrylic acid-containing composition in which decomposition of a polymerization inhibitor during storage is suppressed and which has high quality stability. DETAILED DESCRIPTION

[0052] Some embodiments will be described below, but the present invention is not limited thereto.

[0053] In this specification, a numerical range expressed using "to" means a range including the numerical values ​​described before and after "to" as the lower limit and upper limit, and "A to B" means A or more and B or less. In this specification, the lower limit and upper limit of the numerical range disclosed in the specification can be arbitrarily combined to form a new numerical range.

[0054] [Methacrylic acid-containing composition of the first embodiment]

[0055] The methacrylic acid-containing composition of the first embodiment contains methacrylic acid, Component A1 which is a compound represented by the following formula (11), and Component B as a polymerization inhibitor. The concentration of methacrylic acid is 98.00 to 99.99% by mass.

[0056]

[0057] In formula (11), R 1a , R 2a , R 3a , R 4a , R 5a and R 6a Each independently represents a hydrogen atom, an alkyl group, an alkenyl group, a hydroxyl group, an alkoxy group, an amino group, a monovalent group containing a carbonyl group, an alkylthio group or an arylthio group, and R 1a , R 2a , R 3a , R 4a and R 5a Two or more of them are groups other than hydrogen atoms. 7aIt represents a hydrogen atom, an alkenyl group, an aryl group, a hydroxyl group, an alkoxy group, an amino group, a monovalent group including a carbonyl group, an alkylthio group, or an arylthio group.

[0058] Furthermore, the composition containing methacrylic acid may contain other compounds (component C) and water as long as the concentration of methacrylic acid satisfies 98.00 to 99.99% by mass. Each item will be described in detail below.

[0059] (Methacrylic acid)

[0060] The methacrylic acid-containing composition of the first embodiment contains methacrylic acid. Methacrylic acid can be produced, for example, as a byproduct of the acetone cyanohydrin (ACH) method or as an intermediate of the C4 direct oxidation method. The methacrylic acid contained in the methacrylic acid-containing composition is preferably produced by the C4 direct oxidation method, and more preferably produced by the C4 direct oxidation method using biomass-derived isobutanol as a starting material.

[0061] (ingredient A1)

[0062] The methacrylic acid-containing composition of the first embodiment contains Component A1, which is a compound represented by the above formula (11). The coexistence of Component A1 and Component B described later can suppress the decomposition of the polymerization inhibitor during storage of the methacrylic acid-containing composition. The reason for this is presumed to be as follows.

[0063] It is known that methacrylic acid will polymerize due to free radicals generated during storage, and an inhibitor (component B) is added to prevent polymerization. Component B has an anti-polymerization function by capturing free radicals generated during the storage of methacrylic acid, but since the inhibitor decomposes into other compounds when capturing free radicals, the concentration of component B in the composition containing methacrylic acid during storage slowly decreases, resulting in a slow decrease in the anti-polymerization function. In addition, the unwanted decomposition products generated by component B capturing free radicals slowly increase. As an example of free radicals generated during the storage of methacrylic acid, hydroxyl radicals generated by oxygen molecules absorbing ultraviolet light from sunlight can be cited. Component A1 absorbs ultraviolet light because it is a π-conjugated system compound having a benzene ring, and its absorption wavelength and absorption intensity vary depending on the type of substituent. Component A1 is bonded to the benzene ring because an alkyl group with a suitable large volume and suitable electron donating property is bonded to the benzene ring, so it can absorb ultraviolet light of a wide range of wavelengths. Therefore, when a composition containing methacrylic acid contains component A1, ultraviolet light of a wide range of wavelengths is absorbed to suppress the generation of hydroxyl radicals. Therefore, the free radicals that component B needs to capture are reduced, so that a decrease in the concentration of component B and generation of decomposition products can be suppressed.

[0064] The molecular weight of component A1 is preferably 2000 or less. By making the molecular weight 2000 or less, the number of benzene rings per unit mass in component A1 can be increased, so the effect of the present invention can be obtained with less mass. The molecular weight of component A1 is more preferably 1600 or less, further preferably 1200 or less, and particularly preferably 800 or less.

[0065] In the above formula (11), R 1a , R 2a , R 3a , R 4a , R 5a and R 6a Each independently represents a hydrogen atom, an alkyl group, an alkenyl group, a hydroxyl group, an alkoxy group, an amino group, a monovalent group containing a carbonyl group, an alkylthio group or an arylthio group. 7a represents a hydrogen atom, an alkenyl group, an aryl group, a hydroxyl group, an alkoxy group, an amino group, a monovalent group including a carbonyl group, an alkylthio group or an arylthio group, and R 1a , R 2a , R 3a , R 4a and R 5a Two or more of them are groups other than hydrogen atoms. 7a R represents a hydrogen atom, an alkenyl group, an aryl group, a hydroxyl group, an alkoxy group, an amino group, a monovalent group including a carbonyl group, an alkylthio group or an arylthio group. 1a , R 2a , R 3a , R 4a , R 5a , R 6a and R 7a They may be the same or different.

[0066] In the above formula (11), if R 1a , R 2a , R 3a , R 4a , R 5a , R 6a and R 7a If the steric hindrance of R is large, the benzene ring will be deformed and it will be impossible to maintain the π conjugated system. 1a , R 2a , R 3a , R 4a , R 5a , R 6a and R 7a When the above conditions are met, the volume is of an appropriate size, and the π conjugated system of component A1 is maintained, so that it has the property of absorbing ultraviolet light of a wide range of wavelengths, and the effect of the present invention can be obtained. From the viewpoint of increasing the absorbance of ultraviolet light and inhibiting the generation of hydroxyl radicals, R 1a , R 2a, R 3a , R 4a , R 5a and R 6a Preferably, it is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, a hydroxyl group, an alkoxycarbonyl group having 1 to 6 carbon atoms, an amino group having 0 to 6 carbon atoms, or a monovalent group containing a carbonyl group having 1 to 6 carbon atoms, more preferably a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, a hydroxyl group, or an alkoxycarbonyl group having 1 to 6 carbon atoms, further preferably a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, an isobutyl group, a hydroxyl group, or a methoxy group, and particularly preferably a hydrogen atom, a hydroxyl group, or a methoxy group. In addition, from the viewpoint of increasing the absorbance of ultraviolet light and suppressing the generation of hydroxyl radicals, R 7a Preferred are hydrogen atoms, alkenyl groups having 2 to 5 carbon atoms, aryl groups having 6 to 12 carbon atoms, hydroxyl groups, alkoxycarbonyl groups having 1 to 6 carbon atoms, amino groups having 0 to 6 carbon atoms, or monovalent groups containing carbonyl groups having 1 to 6 carbon atoms; more preferred are hydrogen atoms, carboxyl groups, or alkoxycarbonyl groups having 2 to 6 carbon atoms; and further preferred are hydrogen atoms, carboxyl groups, or methoxycarbonyl groups.

[0067] The alkyl group is a chain (straight or branched) alkyl group or a cyclic alkyl group. Preferably, it is an alkyl group having 1 to 20 carbon atoms, more preferably an alkyl group having 1 to 10 carbon atoms, and further preferably an alkyl group having 1 to 5 carbon atoms. As chain alkyl groups, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, hexyl, octyl, decyl, hydroxymethyl, 1-hydroxyethyl, 2-hydroxyethyl, etc. can be mentioned, preferably methyl, ethyl, n-propyl, isopropyl, tert-butyl. In addition, as cyclic alkyl groups, for example, cyclopentyl, cyclohexyl, cyclooctyl, etc. can be mentioned.

[0068] The alkenyl group is a chain (straight or branched) alkenyl group or a cyclic alkenyl group. Preferably, the alkenyl group has 2 to 20 carbon atoms, more preferably, the alkenyl group has 2 to 10 carbon atoms, and further preferably, the alkenyl group has 2 to 5 carbon atoms. Examples of chain alkenyl groups include vinyl, 1-propenyl, isopropenyl, 2-butenyl, 1,3-butadienyl, 2-pentenyl, and 2-hexenyl. In addition, examples of cyclic alkenyl groups include cyclopentenyl and cyclohexenyl.

[0069] The aryl group is preferably an aryl group having 1 to 20 carbon atoms, and more preferably an aryl group having 1 to 12 carbon atoms. The aryl group includes a heteroaryl group containing oxygen, nitrogen, sulfur, and the like. Examples of the aryl group include phenyl, mesityl, naphthyl, 2-methylphenyl, 3-methylphenyl, 4-methylphenyl, 2,3-dimethylphenyl, 2,4-dimethylphenyl, 2,5-dimethylphenyl, 2,6-dimethylphenyl, 2-ethylphenyl, isothiophenyl, 2-thiophenyl, 2-ethylphenyl, 2-isothio ... Azolyl, isothiazolyl, imidazolyl, oxazolyl, thiazolyl, thiadiazolyl, thienyl, triazolyl, tetrazolyl, pyridyl, pyrazinyl, pyrimidinyl, pyridazinyl, pyrazolyl, pyrrolyl, furanyl, furazanyl, isoquinolyl, isoindolyl, indolyl, quinolyl, pyridothiazolyl, benzimidazolyl, benzo oxazolyl, benzothiazolyl, benzotriazolyl, benzofuranyl, imidazopyridinyl, triazolopyridinyl, purinyl and the like.

[0070] The alkoxy group is preferably an alkoxy group having 1 to 20 carbon atoms, more preferably an alkoxy group having 1 to 10 carbon atoms, and still more preferably an alkoxy group having 1 to 6 carbon atoms. Examples of the alkoxy group include methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, sec-butoxy, tert-butoxy, n-pentoxy, isopentoxy, and phenoxy.

[0071] Amino groups include amino groups with no substituent on the nitrogen atom (-NH 2 ) (carbon number 0), and an amino group in which a part or all of the hydrogen atoms bonded to the nitrogen atom are substituted with carbon atoms. The number of carbon atoms of the amino group in which a part or all of the hydrogen atoms bonded to the nitrogen atom are substituted with carbon atoms is preferably 1 to 20, more preferably 1 to 10, and further preferably 1 to 6. Examples of the amino group include an unsubstituted amino group (—NH 2 ), methylamino, ethylamino, propylamino, butylamino, dimethylamino, diethylamino, aniline, toluidine, anisidine, diphenylamino, N-methyl-N-phenylamino, etc.

[0072] Examples of the monovalent group containing a carbonyl group include a formyl group, an acyl group, a carboxyl group, an amide group, an alkoxycarbonyl group, a thiocarboxyl group, and a thioester group. A monovalent group containing a carbonyl group having 1 to 6 carbon atoms is preferred.

[0073] The acyl group is a substituent formed by connecting a carbonyl group to an alkyl group, an alkenyl group, or an aryl group. The total number of carbon atoms (1) derived from the carbonyl group and the number of carbon atoms derived from the alkyl group, the alkenyl group, or the aryl group is preferably 2 to 20, more preferably 2 to 10, and even more preferably 2 to 6. Examples of the acyl group include acetyl, propionyl, butyryl, vinylcarbonyl, and benzoyl.

[0074] The amide group includes an amide group with no substituent on the nitrogen atom (-CONH 2), and an amide group in which a part or all of the hydrogen atoms bonded to the nitrogen atom are substituted with carbon atoms. The number of carbon atoms in the amide group is preferably 1 to 20, more preferably 1 to 10, and even more preferably 1 to 5, based on the total number of carbon atoms from the carbonyl group (1) and the number of carbon atoms substituted on the nitrogen atom. Examples of the amide group include an unsubstituted amide group, an N-methylamide group, an N-ethylamide group, an N-phenylamide group, an N,N-dimethylamide group, and an N-methyl-N-phenylamide group.

[0075] The alkoxycarbonyl group is a substituent formed by connecting a carbonyl group to an alkoxy group, and is also called an ester group. The total number of carbon atoms (1) derived from the carbonyl group and the number of carbon atoms derived from the alkoxy group is preferably 2 to 20, more preferably 2 to 10, and further preferably 2 to 6. Examples of the alkoxycarbonyl group include methoxycarbonyl, ethoxycarbonyl, butoxycarbonyl, and phenoxycarbonyl.

[0076] The thioester group is a substituent formed by connecting a carbonyl group to an alkylthio group or an arylthio group. The total number of carbon atoms (1) derived from the carbonyl group and the number of carbon atoms derived from the alkylthio group or the arylthio group is preferably 2 to 20, more preferably 2 to 10, and further preferably 2 to 6. Examples of the thioester group include methylthiocarbonyl, ethylthiocarbonyl, butylthiocarbonyl, and phenylthiocarbonyl.

[0077] In addition, the monovalent group containing a carbonyl group may be a substituent in which one or more hydrogen atoms of an alkyl group are replaced by a carbonyl group. Examples of such a substituent include 2-acetoxyethyl, 2-acetylethyl, and 2-(acetoacetoxy)ethyl.

[0078] The alkylthio group is preferably an alkylthio group having 1 to 20 carbon atoms, more preferably an alkylthio group having 1 to 10 carbon atoms, and further preferably an alkylthio group having 1 to 5 carbon atoms. Examples of the alkylthio group include methylthio, ethylthio, propylthio, and isopropylthio.

[0079] The arylthio group is preferably an arylthio group having 1 to 20 carbon atoms, more preferably an arylthio group having 3 to 10 carbon atoms, and further preferably an arylthio group having 6 to 10 carbon atoms. Examples of the arylthio group include a phenylthio group and a tolylthio group.

[0080] Among the compounds satisfying the above conditions, from the viewpoint of quality stability of the methacrylic acid-containing composition during storage, component A1 is preferably methyl 2-phenylisobutyrate, 2-phenylisobutyric acid, 2-isopropylhydroquinone, 2-isopropyl-4-methoxyphenol, 2-methyl-2-phenylpropionamide, 2-(2-hydroxy-5-methoxyphenyl)-2-methylpropionic acid, 2-(2-methoxy-5-hydroxyphenyl)-2-methylpropionic acid, 2-(2,5-dihydroxyphenyl)-2-methylpropionic acid, methyl 2-(2-hydroxy-5-methoxyphenyl)-2-methylpropionic acid, methyl 2-(2-methoxy-5-hydroxyphenyl)-2-methylpropionic acid, or methyl 2-( 2,5-dihydroxyphenyl)-2-methylpropionic acid methyl ester, more preferably 2-phenylisobutyric acid methyl ester, 2-phenylisobutyric acid, 2-isopropylhydroquinone, 2-isopropyl-4-methoxyphenol, 2-(2-hydroxy-5-methoxyphenyl)-2-methylpropionic acid, 2-(2-methoxy-5-hydroxyphenyl)-2-methylpropionic acid, further preferably 2-phenylisobutyric acid methyl ester, 2-phenylisobutyric acid, 2-isopropylhydroquinone, 2-isopropyl-4-methoxyphenol, 2-(2-hydroxy-5-methoxyphenyl)-2-methylpropionic acid, particularly preferably 2-phenylisobutyric acid methyl ester, 2-phenylisobutyric acid, 2-isopropylhydroquinone, 2-isopropyl-4-methoxyphenol.

[0081] Component A1 may be used in one kind or in two or more kinds.

[0082] (ingredient B)

[0083] The composition containing methacrylic acid in the first embodiment contains component B as a polymerization inhibitor. A polymerization inhibitor refers to a compound having the function of inhibiting the polymerization reaction of methacrylic acid. As the polymerization inhibitor, for example, phenolic compounds, quinone compounds, nitrobenzene compounds, N-oxy radical compounds, amine compounds, phosphorus-containing compounds, sulfur-containing compounds, iron-containing compounds, copper-containing compounds and manganese-containing compounds can be cited. By containing component B, the polymerization reaction of methacrylic acid based on the free radical polymerization mechanism during the storage of methacrylic acid can be inhibited. In addition, component B can capture the above-mentioned hydroxyl radicals generated during the storage of methacrylic acid. That is, when the composition containing methacrylic acid contains component B in addition to component A1, the amount of hydroxyl radicals can be reduced by the following two different mechanisms, that is, the generation of hydroxyl radicals can be inhibited by component A1, and the generated hydroxyl radicals can be removed by component B. Therefore, it is believed that the reduction of component B and the generation of decomposition products can be efficiently inhibited.

[0084] Examples of the polymerization inhibitor as a phenolic compound include alkylphenols, hydroxyphenols, aminophenols, nitrophenols, nitrosophenols, alkoxyphenols, and tocopherol.

[0085] Examples of the alkylphenol include o-cresol, m-cresol, p-cresol, 2-tert-butyl-4-methylphenol, 2,4-dimethyl-6-tert-butylphenol, 2,6-di-tert-butyl-4-methylphenol, 2-tert-butylphenol, 4-tert-butylphenol, 2,4-di-tert-butylphenol, 2-methyl-4-tert-butylphenol, 4-tert-butyl-2,6-dimethylphenol, 2,2′-methylenebis(4-ethyl-6-tert-butylphenol), 4,4′-thiobis(3-methyl-6-tert-butylphenol), and 3,5-di-tert-butyl-4-hydroxytoluene.

[0086] Examples of the hydroxyphenol include hydroquinone, 2-methylhydroquinone, 2-tert-butylhydroquinone, 2,5-di-tert-butylhydroquinone, 2,6-di-tert-butylhydroquinone, 2,5-di-tert-amylhydroquinone, 2-tert-butylmethoxyhydroquinone, 2,3,5-trimethylhydroquinone, 2,5-dichlorohydroquinone, 1,2-dihydroxybenzene, 2-acetylhydroquinone, 4-methylcatechol, 4-tert-butylcatechol, 2-methylresorcinol, 4-methylresorcinol, and 2,3-dihydroxyacetophenone.

[0087] Examples of the aminophenol include o-aminophenol, m-aminophenol, p-aminophenol, 2-(N,N-dimethylamino)phenol, and 4-(ethylamino)phenol.

[0088] Examples of the nitrophenol include o-nitrophenol, m-nitrophenol, p-nitrophenol, and 2,4-dinitrophenol.

[0089] Examples of the nitrosophenol include o-nitrosophenol, m-nitrosophenol, p-nitrosophenol, and α-nitroso-β-naphthol.

[0090] Examples of the alkoxyphenol include 2-methoxyphenol, 2-ethoxyphenol, 2-isopropoxyphenol, 2-tert-butoxyphenol, 4-methoxyphenol, 4-ethoxyphenol, 4-propoxyphenol, 4-butoxyphenol, 4-tert-butoxyphenol, 4-heptyloxyphenol, hydroquinone monobenzyl ether, tert-butyl-4-methoxyphenol, di-tert-butyl-4-methoxyphenol, pyrogallol-1,2-dimethyl ether, and hydroquinone monobenzoate.

[0091] Examples of tocopherol include α-tocopherol and 2,3-dihydro-2,2-dimethyl-7-hydroxybenzofuran.

[0092] Examples of the polymerization inhibitor as a quinone compound include p-benzoquinone, chloro-p-benzoquinone, 2,5-dichloro-p-benzoquinone, 2,6-dichloro-p-benzoquinone, tetrachloro-p-benzoquinone, tetrabromo-p-benzoquinone, 2,3-dimethyl-p-benzoquinone, 2,5-dimethyl-p-benzoquinone, methoxy-p-benzoquinone, and methyl-p-benzoquinone.

[0093] Examples of the polymerization inhibitor as a nitrobenzene compound include nitrobenzene, o-dinitrobenzene, m-dinitrobenzene, p-dinitrobenzene, 2,4-dinitrobenzene, dinitrodurene, and 2,2-diphenyl-1-picrylhydrazyl.

[0094] Examples of the polymerization inhibitor as an N-oxyl radical compound include 4-hydroxy-2,2,6,6-tetramethyl-piperidin-N-oxyl radical, 4-oxo-2,2,6,6-tetramethyl-piperidin-N-oxyl radical, 4-acetoxy-2,2,6,6-tetramethyl-piperidin-N-oxyl radical, 2,2,6,6-tetramethyl-piperidin-N-oxyl radical, piperidine-1-oxyl radical, 4-(dimethylamino)-2,2,6,6-tetramethyl-piperidin-N-oxyl radical, 4-amino-2,2,6,6-tetramethyl-piperidin-N-oxyl radical, 4-vinyloxy-2,2,6,6-tetramethyl-piperidin-N-oxyl radical, 4-benzoyloxy-2,2,6,6-tetramethyl-piperidin-N-oxyl radical, -N-oxyl free radical, 2,2,5,5-tetramethyl-piperidinyl-N-oxyl free radical, 3-amino-2,2,5,5-tetramethyl-piperidinyl-N-oxyl free radical, 4,4',4"-tris(2,2,6,6-tetramethyl-piperidinyl-N-oxyl free radical)phosphite, 3-oxo-2,2,5,5-tetramethylpyrrolidine-N-oxyl free radical, pyrrolidine-1-oxyl free radical, 2,2,5,5-tetramethyl-1-oxa-3-azacyclopentyl-3-oxyl free radical, 2,2,5,5-tetramethyl-3-pyrrolinyl-1-oxyl-3-carboxylic acid, 2,2,3,3,5,5,6,6-octamethyl-1,4-diazacyclohexyl-1,4-dioxyl free radical, di-tert-butylnitroxide, di-tert-amylnitroxide, etc.

[0095] Examples of the polymerization inhibitor as an amine compound include N,N-diphenylamine, alkylated diphenylamine, 4,4'-dicumyldiphenylamine, 4,4'-dioctyldiphenylamine, 4-aminodiphenylamine, p-nitrosodiphenylamine, N-nitrosodinaphthylamine, N-nitrosodiphenylamine, N-nitrosophenylnaphthylamine, N-nitrosophenylhydroxylamine, N,N'-dialkyl-p-phenylenediamine (the alkyl groups may be the same or different, each independently having 1 to 4 carbon atoms, and may be linear or branched), N,N'-diphenyl-p-phenylenediamine, N-phenyl-N'-isopropyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-1,4-phenylenediamine, N,N'-di-2-naphthylamine, 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline, 2,2,4-trimethyl-1,2-dihydroquinoline polymer, butyral-α-naphthylamine, N-phenyl-β-naphthylamine, 4-hydroxy-2,2,6,6-tetramethylpiperidine, 4-benzoyloxy-2,2,6,6-tetramethylpiperidine, 1,4-dihydroxy-2,2,6,6-tetramethylpiperidine, 1-hydroxy-4-benzoyloxy-2,2,6,6-tetramethylpiperidine, etc.

[0096] Examples of the polymerization inhibitor as a phosphorus-containing compound include triphenylphosphine, triphenyl phosphite, triethyl phosphite, tris(isodecyl) phosphite, tris(tridecyl) phosphite, phenyl diisooctyl phosphite, phenyl diisodecyl phosphite, phenyl di(tridecyl) phosphite, diphenyl isooctyl phosphite, diphenyl isodecyl phosphite, diphenyl tridecyl phosphite, [1,1-diphenyl-4,4'-diyl-bis[tetrakis-2,4-bis(1,1-dimethylethyl)phenyl]]phosphonate, tris(nonylphenyl) phosphite, 4,4'-isopropylidene diphenol alkyl phosphite, tris(2,4-di-tert-butylphenyl) phosphite, and terphenyl phosphite. Ester, distearyl pentaerythritol diphosphite, di(2,4-di-tert-butylphenyl) pentaerythritol diphosphite, di(nonylphenyl) pentaerythritol diphosphite, phenyl bisphenol A pentaerythritol diphosphite, tetra(tridecyl)-4,4'-butylidene bis(3-methyl-6-tert-butylphenol) diphosphite, hexa(tridecyl)-1,1,3-tri(2-methyl-4-hydroxy-5-tert-butylphenyl) butane triphosphite, 3,5-di-tert-butyl-4-hydroxybenzyl phosphate diethyl ester, bis(4-tert-butylphenyl) phosphate sodium salt, 2,2'-methylene-bis(4,6-di-tert-butylphenyl) phosphate sodium salt, 1,3-bis(diphenoxyphosphoryloxy)benzene, etc.

[0097] Examples of the polymerization inhibitor as a sulfur-containing compound include diphenyl sulfide, phenothiazine, 3-oxophenothiazine, 5-oxophenothiazine, phenothiazine dimer, 1,4-dimercaptobenzene, 1,2-dimercaptobenzene, 2-mercaptophenol, 4-mercaptophenol, 2-(methylthio)phenol, and 3,7-bis(dimethylamino)phenothiazine. Chloride, sulfur (elemental), etc.

[0098] Examples of the polymerization inhibitor as an iron-containing compound include iron (III) chloride and the like.

[0099] Examples of the polymerization inhibitor as a copper compound include copper dimethyldithiocarbamate, copper diethyldithiocarbamate, copper dibutyldithiocarbamate, copper salicylate, copper acetate, copper thiocyanate, copper nitrate, copper chloride, copper carbonate, copper hydroxide, copper acrylate, copper methacrylate, and the like.

[0100] Examples of the polymerization inhibitor as a manganese-containing compound include manganese dialkyldithiocarbamate (the alkyl group is any of methyl, ethyl, propyl and butyl, and may be the same or different), manganese diphenyldithiocarbamate, manganese formate, manganese acetate, manganese octoate, manganese naphthenate, manganese permanganate, and manganese salt of ethylenediaminetetraacetic acid.

[0101] Among the above, from the viewpoint of quality stability of the composition containing methacrylic acid during storage, as component B, at least one polymerization inhibitor selected from phenolic compounds, N-oxyl radical compounds, amine compounds, phosphorus-containing compounds and sulfur-containing compounds is preferred, for example, at least one polymerization inhibitor selected from hydroquinone, 4-methoxyphenol, 2,4-dimethyl-6-tert-butylphenol, 2,6-di-tert-butyl-4-methylphenol, 4-hydroxy-2,2,6,6-tetramethylpiperidinyl-N-oxyl radical, N,N-diphenylamine, N-nitrosodiphenylamine, triphenyl phosphite and phenothiazine is preferred. Component B is more preferably a phenolic compound, for example, at least one polymerization inhibitor selected from hydroquinone, 4-methoxyphenol, 2,4-dimethyl-6-tert-butylphenol and 2,6-di-tert-butyl-4-methylphenol is more preferred. Component B is preferably at least one polymerization inhibitor selected from the group consisting of hydroquinone, 4-methoxyphenol, and 2,6-di-tert-butyl-4-methylphenol. Component B is particularly preferably at least one polymerization inhibitor selected from the group consisting of hydroquinone and 4-methoxyphenol.

[0102] Component B may be one kind or two or more kinds. When Component B contains two or more kinds, the total amount is regarded as the content of Component B.

[0103] When the composition containing methacrylic acid contains a compound corresponding to both component A1 and component B, the compound is regarded as component B. That is, the composition containing methacrylic acid needs to contain component A1 different from the compound. When the compound corresponding to both component A1 and component B contains two or more kinds of compounds, the compound with the highest molar concentration in the composition containing methacrylic acid is regarded as component B, and the other compounds are regarded as component A1.

[0104] (Concentrations of Component A1 and Component B)

[0105] The concentration of component A1 is M A1 (μmol / L), the concentration of component B is M B (μmol / L), from the viewpoint of the efficiency of inhibiting the consumption of the polymerization inhibitor, M B / M A1 It is preferably 0.0005 to 100, more preferably 0.001 to 85, further preferably 0.005 to 70, particularly preferably 0.005 to 60.

[0106] M A1 It is preferably 1 to 500,000 μmol / L. A1 When the content of M is 1 μmol / L or more, the effect of suppressing the consumption of the polymerization inhibitor can be fully obtained. A1 When the concentration is 500,000 μmol / L or less, the amount of impurities in producing a methacrylic acid polymer by polymerizing the methacrylic acid-containing composition of the first embodiment can be reduced, thereby preventing adverse effects on the physical properties of the polymer. A1 The lower limit of M is more preferably 10 μmol / L or more, further preferably 30 μmol / L or more, more preferably 50 μmol / L or more, and particularly preferably 70 μmol / L or more. A1 The upper limit is more preferably 450,000 μmol / L or less, further preferably 400,000 μmol / L or less, particularly preferably 350,000 μmol / L or less, and particularly preferably 300,000 μmol / L or less.

[0107] M B It is preferably 1 to 50000 μmol / L. B When the content of M is 1 μmol / L or more, the effect of suppressing the consumption of the polymerization inhibitor can be fully obtained. B When the concentration is 50000 μmol / L or less, the amount of impurities in producing a methacrylic acid polymer by polymerizing the methacrylic acid-containing composition of the first embodiment can be reduced, thereby preventing adverse effects on the physical properties of the polymer. BThe lower limit of M is more preferably 10 μmol / L or more, further preferably 100 μmol / L or more, particularly preferably 1000 μmol / L or more, and even more preferably 2000 μmol / L or more. B The upper limit is more preferably 40000 μmol / L or less, further preferably 30000 μmol / L or less, and particularly preferably 25000 μmol / L or less.

[0108] (Methacrylic acid concentration)

[0109] The methacrylic acid concentration of the methacrylic acid-containing composition of the first embodiment is 98.00 to 99.99% by mass. By setting the methacrylic acid concentration to 98.00% by mass or more, the amount of impurities when producing a methacrylic acid polymer by polymerization of the methacrylic acid-containing composition of the first embodiment can be reduced, thereby preventing adverse effects on the physical properties of the polymer. In addition, by setting the methacrylic acid concentration to 99.99% by mass or less, the purification cost can be reduced. The lower limit of the methacrylic acid concentration is more preferably 98.50% or more, further preferably 99.00% or more, particularly preferably 99.50% or more, and most preferably 99.80% or more by mass.

[0110] (Ingredient C)

[0111] The composition containing methacrylic acid of the first embodiment may further contain component C as another compound as long as the concentration of methacrylic acid is 98.00 to 99.99% by mass. Examples of component C include impurities generated in the production process of methacrylic acid. For example, methacrylic acid may contain diacetyl as an impurity. From the viewpoint of reducing the coloration of the composition containing methacrylic acid, the concentration of diacetyl is preferably 55 μmol / L or less, more preferably 20 μmol / L or less, further preferably 10 μmol / L or less, and particularly preferably 1 μmol / L or less.

[0112] (Analysis of Compositions Containing Methacrylic Acid)

[0113] The composition containing methacrylic acid can be confirmed to contain component A1, component B, component C and water by, for example, GC-MS measurement. In the GC-MS spectrum of the composition containing methacrylic acid, if there is a peak at the same retention time as the standard of component A1, and the m / z value detected in the mass spectrum of the peak is consistent with the exact mass of component A1, it can be determined that the composition containing methacrylic acid contains component A1. In the case where a standard of component A1 cannot be obtained, when the pattern of the mass spectrum of the peak appearing in the GC-MS spectrum of the composition containing methacrylic acid is consistent with the pattern of the mass spectrum of component A1 included in the mass spectrum database, it can be determined that the peak is the peak of component A1. That is, it can be determined that the composition containing methacrylic acid contains component A1. As mass spectrum databases, NIST20, NIST17, NIST14, NIST14s, etc. can be cited. In addition, when the volatility is low and it cannot be detected by GC-MS measurement, LC-MS can be used for detection. Component B, component C and water can also be confirmed by the same method.

[0114] In addition, the concentration of methacrylic acid can be calculated by, for example, performing GC-FID measurement on a composition containing methacrylic acid, quantifying it using the area percentage method, and correcting it using the amount of water quantified by a Karl Fischer titrator. The concentration of component A1 can be quantified by, for example, performing GC measurement on a composition containing methacrylic acid and using an internal standard method. When a standard product of component A1 is not available and quantification cannot be performed using the internal standard method, the concentration of component A1 can be calculated by performing GC-FID measurement on any organic compound whose content is known and using the following formula.

[0115]

[0116] Here, N is the number of carbon atoms in one molecule of an organic compound with a known concentration. A1 is the number of carbon atoms in one molecule of component A1, S A1 is the peak area of ​​component A1, S is the peak area of ​​the organic compound of known concentration, and M is the concentration (μmol / L) of the organic compound of known concentration.

[0117] When volatility is low and quantification by GC is not possible, quantification can be performed by chromatography such as LC.

[0118] The concentrations of Component B and Component C can also be calculated by the same method as that of Component A1.

[0119] In addition, the presence of water in the composition containing methacrylic acid and the concentration of water can be confirmed by Karl Fischer method.

[0120] [Method for producing a composition containing methacrylic acid]

[0121] As a method for producing a composition containing methacrylic acid in the first embodiment, there can be mentioned a method of adding component A1 and component B to methacrylic acid. Methacrylic acid can use a commercial product, or methacrylic acid produced by a known method such as the acetone cyanohydrin (ACH) method and the C4 direct oxidation method. Component A1 and component B can use a commercial product, or a compound synthesized by a known method. When a commercial product containing component B is used as methacrylic acid, component B contained in the commercial product can be used as component B of the present invention, or component B can be added. When a substance produced by a known method such as the acetone cyanohydrin (ACH) method and the C4 direct oxidation method is used for methacrylic acid, component A1 or component B can be added in the middle of the raw material or the production process to produce a composition containing methacrylic acid. In addition, when component A1 or component B is generated as a by-product in the methacrylic acid production process, a composition containing methacrylic acid can also be produced by leaving a portion of the generated component A1 or component B.

[0122] [Evaluation method of storage stability and thermal stability]

[0123] The first embodiment has high quality stability of the composition containing methacrylic acid during storage. As an evaluation method for the quality stability of the composition containing methacrylic acid during storage, for example, a method of actually storing the composition containing methacrylic acid for a long time and confirming the reduction in the amount of the polymerization inhibitor can be cited. In addition, from the perspective of simplicity of operation, a method of heating the composition containing methacrylic acid for a short time and confirming the reduction in the amount of the polymerization inhibitor can be used. When heating for a short time, the heating temperature is preferably 50 to 100°C, and the heating time is preferably 1 to 24 hours. In the present invention, the quality stability of the composition containing methacrylic acid during storage is evaluated based on the reduction in the amount of the polymerization inhibitor when the composition containing methacrylic acid is stored at 25°C for 21 days.

[0124] [Method for producing methacrylic acid ester according to the first aspect]

[0125] The method for producing a methacrylic acid ester of the first embodiment includes a step of esterifying methacrylic acid in the methacrylic acid-containing composition of the first embodiment.

[0126] The alcohol to be reacted with the composition containing methacrylic acid is not particularly limited, and examples thereof include methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, and the like. Examples of the methacrylic acid esters obtained include methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, butyl methacrylate, and isobutyl methacrylate. The esterification reaction may be carried out in the presence of an acidic catalyst such as a sulfonic acid type cation exchange resin. The temperature in the esterification reaction is preferably 50 to 200°C.

[0127] The pressure during the esterification reaction, the position of the catalyst in the reactor, the ratio of the catalyst in the reactor, and the like are not particularly limited, and commonly used methods can be applied.

[0128] [Method for producing methacrylic acid polymer according to the first aspect]

[0129] The method for producing a methacrylic acid polymer of the first embodiment includes a step of polymerizing a polymerizable composition containing the methacrylic acid-containing composition of the first embodiment.

[0130] The polymerizable composition may further contain a monomer copolymerizable with methacrylic acid and other additives as necessary.

[0131] Examples of the monomer copolymerizable with methacrylic acid include the following monomers.

[0132] Methacrylates such as methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, 2-ethylhexyl methacrylate, phenyl methacrylate, or benzyl methacrylate;

[0133] Acrylates such as methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, tert-butyl acrylate, or 2-ethylhexyl acrylate;

[0134] Unsaturated carboxylic acids such as acrylic acid, maleic acid, or itaconic acid;

[0135] Unsaturated carboxylic anhydrides such as maleic anhydride or itaconic anhydride;

[0136] Maleimides such as N-phenylmaleimide or N-cyclohexylmaleimide;

[0137] A vinyl monomer containing a hydroxyl group, such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, or 2-hydroxypropyl methacrylate;

[0138] Vinyl esters such as vinyl acetate or vinyl benzoate;

[0139] Vinyl chloride, vinylidene chloride and their derivatives;

[0140] Nitrogen-containing vinyl monomers such as methacrylamide or acrylonitrile;

[0141] Monomers containing epoxy groups such as glycidyl acrylate or glycidyl methacrylate;

[0142] Aromatic vinyl monomers such as styrene or α-methylstyrene;

[0143] Alkanediol di(meth)acrylates such as ethylene glycol di(meth)acrylate, 1,2-propylene glycol di(meth)acrylate, 1,3-butylene glycol di(meth)acrylate, or 1,6-hexanediol di(meth)acrylate;

[0144] Polyoxyalkylene glycol di(meth)acrylates such as diethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, triethylene glycol (meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, or neopentyl glycol di(meth)acrylate;

[0145] Vinyl monomers having two or more ethylenically unsaturated bonds in the molecule, such as divinylbenzene;

[0146] An unsaturated polyester prepolymer obtained from at least one polycarboxylic acid including an ethylenically unsaturated polycarboxylic acid and at least one diol;

[0147] A vinyl ester prepolymer obtained by modifying the epoxy group terminal with acrylic acid.

[0148] Among the above, the monomer copolymerizable with methacrylic acid is preferably at least one selected from methacrylic acid esters and acrylates. The monomer copolymerizable with methacrylic acid is more preferably methacrylic acid ester, and particularly preferably methyl methacrylate.

[0149] The monomer copolymerizable with methacrylic acid may be one or two or more. In addition, when component A1 is a monomer copolymerizable with methacrylic acid, component A1 may be used as a monomer copolymerizable with methacrylic acid, or a monomer copolymerizable with methacrylic acid different from component A1 may be used.

[0150] In the polymerizable composition, the content of the monomer copolymerizable with methacrylic acid is preferably 50.00 to 99.99 parts by mass relative to 100 parts by mass of the polymerizable composition. The lower limit of the content of the monomer copolymerizable with methacrylic acid is more preferably 60 parts by mass or more, further preferably 70 parts by mass or more, particularly preferably 80 parts by mass or more, and most preferably 90 parts by mass or more, relative to 100 parts by mass of the polymerizable composition. The upper limit of the content of the monomer copolymerizable with methacrylic acid is more preferably 99.9 parts by mass or less, further preferably 99 parts by mass or less, relative to 100 parts by mass of the polymerizable composition.

[0151] As other additives, for example, polymerization initiators, chain transfer agents, mold release agents, lubricants, plasticizers, antioxidants, antistatic agents, light stabilizers, ultraviolet absorbers, flame retardants, flame retardant aids, polymerization inhibitors, fillers, pigments, dyes, silane coupling agents, leveling agents, defoamers, and fluorescent agents can be cited. The other additives can be one or more.

[0152] As other additives, a polymerization initiator is preferable. As the polymerization initiator, for example, the following compounds can be mentioned.

[0153] Azo compounds such as 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), 2,2'-azobis(2-methylpropionitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2,4,4-trimethylpentane), 2,2'-azobis(2-methylpropane), 1,1-azobis(cyclohexanecarbonitrile), and 2,2'-azobisisobutyric acid dimethyl ester;

[0154] Benzoyl peroxide, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, 1,1-bis(tert-butylperoxy)cyclohexane, 1,1-bis(tert-butylperoxy)-3,5,5-trimethylcyclohexane, tert-butyl peroxy-2-ethylhexanoate, tert-butyl peroxyisobutyrate, tert-butyl peroxybenzoate, tert-hexyl peroxybenzoate, tert-butyl peroxyisopropyl monocarbonate, tert-butyl peroxy-3,5,5-trimethylhexanoate, tert-butyl peroxylaurate, tert-butyl peroxyacetate, tert-hexyl peroxyisopropyl monocarbonate, tert-ethyl peroxy Organic peroxides such as tert-hexyl hexanoate, tert-amyl peroxy-2-ethylhexanoate, 1,1,3,3-tetramethylbutyl peroxyethylhexanoate, 1,1,2-trimethylpropyl peroxy-2-ethylhexanoate, 1,1,3,3-tetramethylbutyl peroxyisopropyl monocarbonate, 1,1,2-trimethylpropyl peroxyisopropyl monocarbonate, 1,1,3,3-tetramethylbutyl peroxyisononanoate, 1,1,2-trimethylpropyl peroxy-isononanoate, di-tert-butyl peroxide, di-tert-hexyl peroxide, lauroyl peroxide, and dilauroyl peroxide;

[0155] Persulfate compounds such as potassium persulfate;

[0156] Redox polymerization initiator.

[0157] Among the above, the polymerization initiator is preferably at least one selected from azo compounds and organic peroxides from the viewpoint of storage stability and reactivity of methacrylic acid with a copolymerizable monomer.

[0158] The amount of the polymerization initiator used is preferably 0.0001 to 1 part by mass based on 100 parts by mass of the total of methacrylic acid and the monomer copolymerizable with methacrylic acid.

[0159] Examples of the polymerization method for the polymerizable composition include bulk polymerization, solution polymerization, emulsion polymerization, and suspension polymerization.

[0160] The polymerization temperature is preferably 125 to 210° C. This allows for an appropriate polymerization rate. More preferably, the lower limit of the polymerization temperature is 130° C. or higher and the upper limit is 180° C. or lower. The polymerization time is not particularly limited and may be, for example, 0.5 to 24 hours.

[0161] [Methacrylic acid-containing composition of the second embodiment]

[0162] In the first embodiment of the second aspect, the methacrylic acid-containing composition contains methacrylic acid, component A21 which is a compound represented by the following formula (21), and a polymerization inhibitor (component B). The concentration of methacrylic acid is 98.00 to 99.99% by mass.

[0163]

[0164] In formula (21), R 1b , R 2b , R 3b and R 4b Each independently represents a hydrogen atom, an alkyl group, an alkenyl group, an aryl group, a hydroxyl group, an alkoxy group, an amino group, a monovalent group including a carbonyl group, an alkylthio group or an arylthio group. 1b With R 2b , R 3b With R 4b They may be connected to each other to form a ring.

[0165] Furthermore, the composition containing methacrylic acid may contain other compounds (component C) and water as long as the concentration of methacrylic acid satisfies 98.00 to 99.99% by mass. Each item will be described in detail below.

[0166] (Methacrylic acid)

[0167] The methacrylic acid-containing composition of the second embodiment contains methacrylic acid. Methacrylic acid can be produced, for example, as a byproduct of the acetone cyanohydrin (ACH) method or as an intermediate of the C4 direct oxidation method. The methacrylic acid contained in the methacrylic acid-containing composition is preferably produced by the C4 direct oxidation method, and more preferably produced by the C4 direct oxidation method using biomass-derived isobutanol as a starting material.

[0168] (ingredient A21)

[0169] The first embodiment of the methacrylic acid-containing composition of the second aspect contains the compound represented by the above formula (21), namely component A21. The coexistence of component A21 and component B described later can suppress the decomposition of the polymerization inhibitor during storage of the methacrylic acid-containing composition. The reason for this is presumed to be as follows.

[0170] It is known that methacrylic acid will polymerize due to free radicals generated during storage, and an inhibitor (component B) is added to prevent polymerization. Component B has an anti-polymerization function by capturing free radicals generated during storage of methacrylic acid, but since the inhibitor decomposes into other compounds when capturing free radicals, the concentration of component B in the composition containing methacrylic acid gradually decreases during storage, resulting in a gradual decrease in the anti-polymerization function. In addition, the unwanted decomposition products generated by component B capturing free radicals gradually increase. As an example of free radicals generated during storage of methacrylic acid, hydroxyl radicals generated by oxygen molecules absorbing ultraviolet light from sunlight can be cited. Component A21 absorbs ultraviolet light because it has an aromatic ring, and its absorption wavelength varies depending on the type of substituent. Component A21 having a structure represented by the above formula (21) can absorb ultraviolet light in a wide range of wavelengths. Therefore, by containing component A21 in the composition containing methacrylic acid, ultraviolet light in a wide range of wavelengths is absorbed, and the generation of hydroxyl radicals due to the absorption of ultraviolet light by oxygen molecules is suppressed. Therefore, the free radicals that component B needs to capture are reduced, thereby suppressing the reduction in the concentration of component B and the generation of decomposition products.

[0171] The molecular weight of component A21 is preferably 1000 or less. As a result, the number of pyrazine rings per unit mass of component A21 increases, so the effect of the present invention can be obtained with a small amount of component A21. The molecular weight of component A21 is more preferably 800 or less, further preferably 600 or less, and particularly preferably 400 or less.

[0172] In the above formula (21), R 1b , R 2b , R 3b and R 4b Each independently represents a hydrogen atom, an alkyl group, an alkenyl group, an aryl group, a hydroxyl group, an alkoxy group, an amino group, a monovalent group including a carbonyl group, an alkylthio group or an arylthio group. 1b , R 2b, R 3b and R 4b Can be the same or different.

[0173] From the perspective of increasing the absorbance of ultraviolet light and inhibiting the generation of hydroxyl radicals, R 1b , R 2b , R 3b and R 4b Preferred are hydrogen atoms, alkyl groups having 1 to 5 carbon atoms, alkenyl groups having 2 to 5 carbon atoms, aryl groups having 6 to 12 carbon atoms, alkoxy groups having 1 to 6 carbon atoms, amino groups having 0 to 6 carbon atoms, monovalent groups containing carbonyl groups having 1 to 6 carbon atoms, alkylthio groups having 1 to 5 carbon atoms, or arylthio groups having 6 to 10 carbon atoms; more preferred are hydrogen atoms, alkyl groups having 1 to 5 carbon atoms, alkoxy groups having 1 to 6 carbon atoms, monovalent groups containing carbonyl groups having 1 to 6 carbon atoms, or alkylthio groups having 6 to 10 carbon atoms; further preferred are hydrogen atoms, methyl groups, ethyl groups, n-propyl groups, isopropyl groups, methylthio groups, methoxy groups, carboxyl groups, carbonylmethoxy groups, and hydroxymethyl groups; and particularly preferred are hydrogen atoms, methyl groups, isopropyl groups, methylthio groups, methoxy groups, carboxyl groups, carbonylmethoxy groups, and hydroxymethyl groups.

[0174] The alkyl group is a chain (straight or branched) alkyl group or a cyclic alkyl group. Preferably, it is an alkyl group having 1 to 20 carbon atoms, more preferably an alkyl group having 1 to 10 carbon atoms, and further preferably an alkyl group having 1 to 5 carbon atoms. As chain alkyl groups, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, hexyl, octyl, decyl, hydroxymethyl, 1-hydroxyethyl, 2-hydroxyethyl, etc. can be mentioned, preferably methyl, ethyl, n-propyl, isopropyl. In addition, as cyclic alkyl groups, for example, cyclopentyl, cyclohexyl, cyclooctyl, etc. can be mentioned.

[0175] The alkenyl group is a chain (straight or branched) alkenyl group or a cyclic alkenyl group. Preferably, the alkenyl group has 2 to 20 carbon atoms, more preferably, the alkenyl group has 2 to 10 carbon atoms, and further preferably, the alkenyl group has 2 to 5 carbon atoms. Examples of chain alkenyl groups include vinyl, 1-propenyl, isopropenyl, 2-butenyl, 1,3-butadienyl, 2-pentenyl, and 2-hexenyl. In addition, examples of cyclic alkenyl groups include cyclopentenyl and cyclohexenyl.

[0176] The aryl group is preferably an aryl group having 1 to 20 carbon atoms, and more preferably an aryl group having 1 to 12 carbon atoms. The aryl group includes a heteroaryl group containing oxygen, nitrogen, sulfur, and the like. Examples of the aryl group include phenyl, mesityl, naphthyl, 2-methylphenyl, 3-methylphenyl, 4-methylphenyl, 2,3-dimethylphenyl, 2,4-dimethylphenyl, 2,5-dimethylphenyl, 2,6-dimethylphenyl, 2-ethylphenyl, isothiophenyl, 2-thiophenyl, 2-ethylphenyl, 2-isothio ... Azolyl, isothiazolyl, imidazolyl, oxazolyl, thiazolyl, thiadiazolyl, thienyl, triazolyl, tetrazolyl, pyridyl, pyrazinyl, pyrimidinyl, pyridazinyl, pyrazolyl, pyrrolyl, furanyl, furazanyl, isoquinolyl, isoindolyl, indolyl, quinolyl, pyridothiazolyl, benzimidazolyl, benzo oxazolyl, benzothiazolyl, benzotriazolyl, benzofuranyl, imidazopyridinyl, triazolopyridinyl, purinyl.

[0177] The alkoxy group is preferably an alkoxy group having 1 to 20 carbon atoms, more preferably an alkoxy group having 1 to 10 carbon atoms, further preferably an alkoxy group having 1 to 6 carbon atoms, and particularly preferably an alkoxy group having 1 to 5 carbon atoms. Examples of the alkoxy group include methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, sec-butoxy, tert-butoxy, n-pentoxy, isopentoxy, and phenoxy.

[0178] Amino groups include amino groups with no substituent on the nitrogen atom (-NH 2 ) (carbon number 0), and an amino group in which a part or all of the hydrogen atoms bonded to the nitrogen atom are substituted with carbon atoms. The number of carbon atoms of the amino group in which a part or all of the hydrogen atoms bonded to the nitrogen atom are substituted with carbon atoms is preferably 1 to 20, more preferably 1 to 10, and further preferably 1 to 6. Examples of the amino group include an unsubstituted amino group (—NH 2 ), methylamino, ethylamino, propylamino, butylamino, dimethylamino, diethylamino, aniline, toluidine, anisidine, diphenylamino, N-methyl-N-phenylamino, etc.

[0179] Examples of the monovalent group containing a carbonyl group include a formyl group, an acyl group, a carboxyl group, an amide group, an alkoxycarbonyl group, a thiocarboxyl group, and a thioester group. A monovalent group containing a carbonyl group having 1 to 6 carbon atoms is preferred.

[0180] The acyl group is a substituent formed by connecting a carbonyl group to an alkyl group, an alkenyl group, or an aryl group. The total number of carbon atoms (1) derived from the carbonyl group and the number of carbon atoms derived from the alkyl group, the alkenyl group, or the aryl group is preferably 2 to 20, more preferably 2 to 10, and even more preferably 2 to 6. Examples of the acyl group include acetyl, propionyl, butyryl, vinylcarbonyl, and benzoyl.

[0181] The amide group includes an amide group with no substituent on the nitrogen atom (-CONH 2), and an amide group in which a part or all of the hydrogen atoms bonded to the nitrogen atom are substituted with carbon atoms. The number of carbon atoms in the amide group is preferably 1 to 20, more preferably 1 to 10, and even more preferably 1 to 5, based on the total number of carbon atoms from the carbonyl group (1) and the number of carbon atoms substituted on the nitrogen atom. Examples of the amide group include an unsubstituted amide group, an N-methylamide group, an N-ethylamide group, an N-phenylamide group, an N,N-dimethylamide group, and an N-methyl-N-phenylamide group.

[0182] The alkoxycarbonyl group is a substituent formed by connecting a carbonyl group to an alkoxy group, and is also called an ester group. The total number of carbon atoms (1) derived from the carbonyl group and the number of carbon atoms derived from the alkoxy group is preferably 2 to 20, more preferably 2 to 10, and further preferably 2 to 6. Examples of the alkoxycarbonyl group include methoxycarbonyl, ethoxycarbonyl, butoxycarbonyl, and phenoxycarbonyl.

[0183] The thioester group is a substituent formed by connecting a carbonyl group to an alkylthio group or an arylthio group. The total number of carbon atoms (1) derived from the carbonyl group and the number of carbon atoms derived from the alkylthio group or the arylthio group is preferably 2 to 20, more preferably 2 to 10, and further preferably 2 to 6. Examples of the thioester group include methylthiocarbonyl, ethylthiocarbonyl, butylthiocarbonyl, and phenylthiocarbonyl.

[0184] In addition, the monovalent group containing a carbonyl group may be a substituent in which one or more hydrogen atoms of an alkyl group are replaced by a carbonyl group. Examples of such a substituent include 2-acetoxyethyl, 2-acetylethyl, and 2-(acetoacetoxy)ethyl.

[0185] The alkylthio group is preferably an alkylthio group having 1 to 20 carbon atoms, more preferably an alkylthio group having 1 to 10 carbon atoms, and further preferably an alkylthio group having 1 to 5 carbon atoms. Examples of the alkylthio group include methylthio, ethylthio, propylthio, and isopropylthio.

[0186] The arylthio group is preferably an arylthio group having 1 to 20 carbon atoms, more preferably an arylthio group having 3 to 10 carbon atoms, and further preferably an arylthio group having 6 to 10 carbon atoms. Examples of the arylthio group include a phenylthio group and a tolylthio group.

[0187] Among the compounds satisfying the above conditions, from the viewpoint of quality stability of the methacrylic acid-containing composition during storage, component A21 is preferably 2,3,5,6-tetramethylpyrazine, pyrazine, 2,3,5-trimethylpyrazine, 2-methoxypyrazine, 2-isopropyl-3-methoxypyrazine, 2,5-dimethylpyrazine, 2-aminopyrazine, 2-pyrazinecarboxylic acid methyl ester, 2-(methylthio)pyrazine, 2-pyrazinemethanol, quinoxaline, 2-vinylpyrazine, 2,5-diisopropylpyrazine, 2-ethyl-3,5-dimethylpyrazine, 2,5-dimethyl-3-isobutylpyrazine, 2-isopropyl-3-methoxy-5-isobutylpyrazine, 2,5-dimethyl-3-(methylthio)pyrazine, pyrazinemethylamine, 2-phenyl The present invention further comprises 2,3,5,6-tetramethylpyrazine, pyrazine, 2,3,5-trimethylpyrazine, 2-methoxypyrazine, 2-isopropyl-3-methoxypyrazine, 2,5-dimethylpyrazine, 2-aminopyrazine, methyl 2-pyrazinecarboxylate, 2-(methylthio)pyrazine, 2-pyrazinemethanol, quinoxaline, or 2-vinylpyrazine, and further preferably 2,3,5,6-tetramethylpyrazine, pyrazine, 2,3,5-trimethylpyrazine, 2-methoxypyrazine, 2-isopropyl-3-methoxypyrazine, 2,5-dimethylpyrazine, methyl 2-pyrazinecarboxylate, 2-(methylthio)pyrazine, and 2-pyrazinemethanol.

[0188] The component A21 may be one kind or two or more kinds.

[0189] (ingredient B)

[0190] In the first embodiment of the second mode, the composition containing methacrylic acid contains component B. Component B is a compound that acts as an inhibitor. In the present specification, an inhibitor refers to a compound that has the function of inhibiting the polymerization reaction of methacrylic acid. As an inhibitor, for example, phenolic compounds, quinone compounds, nitrobenzene compounds, N-oxy radical compounds, amine compounds, phosphorus-containing compounds, sulfur-containing compounds, iron-containing compounds, copper-containing compounds and manganese-containing compounds can be cited. By containing component B, the polymerization reaction of methacrylic acid based on the free radical polymerization mechanism during the storage of methacrylic acid can be inhibited. In addition, component B can capture the above-mentioned hydroxyl radicals generated during the storage of methacrylic acid. That is, when the composition containing methacrylic acid contains component B in addition to component A21, the amount of hydroxyl radicals can be reduced by the following two different mechanisms, that is, component A21 can be used to inhibit the generation of hydroxyl radicals, and component B can be used to remove the generated hydroxyl radicals. Therefore, it is believed that the reduction of component B can be efficiently suppressed.

[0191] Examples of the polymerization inhibitor as a phenolic compound include alkylphenols, hydroxyphenols, aminophenols, nitrophenols, nitrosophenols, alkoxyphenols, and tocopherol.

[0192] Examples of the alkylphenol include o-cresol, m-cresol, p-cresol, 2-tert-butyl-4-methylphenol, 2,4-dimethyl-6-tert-butylphenol, 2,6-di-tert-butyl-4-methylphenol, 2-tert-butylphenol, 4-tert-butylphenol, 2,4-di-tert-butylphenol, 2-methyl-4-tert-butylphenol, 4-tert-butyl-2,6-dimethylphenol, 2,2′-methylenebis(4-ethyl-6-tert-butylphenol), 4,4′-thiobis(3-methyl-6-tert-butylphenol), and 3,5-di-tert-butyl-4-hydroxytoluene.

[0193] Examples of the hydroxyphenol include hydroquinone, 2-methylhydroquinone, 2-tert-butylhydroquinone, 2,5-di-tert-butylhydroquinone, 2,6-di-tert-butylhydroquinone, 2,5-di-tert-amylhydroquinone, 2-tert-butylmethoxyhydroquinone, 2,3,5-trimethylhydroquinone, 2,5-dichlorohydroquinone, 1,2-dihydroxybenzene, 2-acetylhydroquinone, 4-methylcatechol, 4-tert-butylcatechol, 2-methylresorcinol, 4-methylresorcinol, and 2,3-dihydroxyacetophenone.

[0194] Examples of the aminophenol include o-aminophenol, m-aminophenol, p-aminophenol, 2-(N,N-dimethylamino)phenol, and 4-(ethylamino)phenol.

[0195] Examples of the nitrophenol include o-nitrophenol, m-nitrophenol, p-nitrophenol, and 2,4-dinitrophenol.

[0196] Examples of the nitrosophenol include o-nitrosophenol, m-nitrosophenol, p-nitrosophenol, and α-nitroso-β-naphthol.

[0197] Examples of the alkoxyphenol include 2-methoxyphenol, 2-ethoxyphenol, 2-isopropoxyphenol, 2-tert-butoxyphenol, 4-methoxyphenol, 4-ethoxyphenol, 4-propoxyphenol, 4-butoxyphenol, 4-tert-butoxyphenol, 4-heptyloxyphenol, hydroquinone monobenzyl ether, tert-butyl-4-methoxyphenol, di-tert-butyl-4-methoxyphenol, pyrogallol-1,2-dimethyl ether, and hydroquinone monobenzoate.

[0198] Examples of tocopherol include α-tocopherol and 2,3-dihydro-2,2-dimethyl-7-hydroxybenzofuran.

[0199] Examples of the polymerization inhibitor as a quinone compound include p-benzoquinone, chloro-p-benzoquinone, 2,5-dichloro-p-benzoquinone, 2,6-dichloro-p-benzoquinone, tetrachloro-p-benzoquinone, tetrabromo-p-benzoquinone, 2,3-dimethyl-p-benzoquinone, 2,5-dimethyl-p-benzoquinone, methoxy-p-benzoquinone, and methyl-p-benzoquinone.

[0200] Examples of the polymerization inhibitor as a nitrobenzene compound include nitrobenzene, o-dinitrobenzene, m-dinitrobenzene, p-dinitrobenzene, 2,4-dinitrobenzene, dinitrodurene, and 2,2-diphenyl-1-picrylhydrazyl.

[0201] Examples of the polymerization inhibitor as an N-oxyl radical compound include 4-hydroxy-2,2,6,6-tetramethyl-piperidin-N-oxyl radical, 4-oxo-2,2,6,6-tetramethyl-piperidin-N-oxyl radical, 4-acetoxy-2,2,6,6-tetramethyl-piperidin-N-oxyl radical, 2,2,6,6-tetramethyl-piperidin-N-oxyl radical, piperidine-1-oxyl radical, 4-(dimethylamino)-2,2,6,6-tetramethyl-piperidin-N-oxyl radical, 4-amino-2,2,6,6-tetramethyl-piperidin-N-oxyl radical, 4-vinyloxy-2,2,6,6-tetramethyl-piperidin-N-oxyl radical, 4-benzoyloxy-2,2,6,6-tetramethyl-piperidin-N-oxyl radical, -N-oxyl free radical, 2,2,5,5-tetramethyl-piperidinyl-N-oxyl free radical, 3-amino-2,2,5,5-tetramethyl-piperidinyl-N-oxyl free radical, 4,4',4"-tris(2,2,6,6-tetramethyl-piperidinyl-N-oxyl free radical)phosphite, 3-oxo-2,2,5,5-tetramethylpyrrolidine-N-oxyl free radical, pyrrolidine-1-oxyl free radical, 2,2,5,5-tetramethyl-1-oxa-3-azacyclopentyl-3-oxyl free radical, 2,2,5,5-tetramethyl-3-pyrrolinyl-1-oxyl-3-carboxylic acid, 2,2,3,3,5,5,6,6-octamethyl-1,4-diazacyclohexyl-1,4-dioxyl free radical, di-tert-butylnitroxide, di-tert-amylnitroxide, etc.

[0202] Examples of the polymerization inhibitor as an amine compound include N,N-diphenylamine, alkylated diphenylamine, 4,4'-dicumyldiphenylamine, 4,4'-dioctyldiphenylamine, 4-aminodiphenylamine, p-nitrosodiphenylamine, N-nitrosodinaphthylamine, N-nitrosodiphenylamine, N-nitrosophenylnaphthylamine, N-nitrosophenylhydroxylamine, N,N'-dialkyl-p-phenylenediamine (the alkyl groups may be the same or different, each independently having 1 to 4 carbon atoms, and may be linear or branched), N,N'-diphenyl-p-phenylenediamine, N-phenyl-N'-isopropyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-1,4-phenylenediamine, N,N'-di-2-naphthylamine, 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline, 2,2,4-trimethyl-1,2-dihydroquinoline polymer, butyral-α-naphthylamine, N-phenyl-β-naphthylamine, 4-hydroxy-2,2,6,6-tetramethylpiperidine, 4-benzoyloxy-2,2,6,6-tetramethylpiperidine, 1,4-dihydroxy-2,2,6,6-tetramethylpiperidine, 1-hydroxy-4-benzoyloxy-2,2,6,6-tetramethylpiperidine, etc.

[0203] Examples of the polymerization inhibitor as a phosphorus-containing compound include triphenylphosphine, triphenyl phosphite, triethyl phosphite, tris(isodecyl) phosphite, tris(tridecyl) phosphite, phenyl diisooctyl phosphite, phenyl diisodecyl phosphite, phenyl di(tridecyl) phosphite, diphenyl isooctyl phosphite, diphenyl isodecyl phosphite, diphenyl tridecyl phosphite, [1,1-diphenyl-4,4'-diyl-bis[tetrakis-2,4-bis(1,1-dimethylethyl)phenyl]]phosphonate, tris(nonylphenyl) phosphite, 4,4'-isopropylidene diphenol alkyl phosphite, tris(2,4-di-tert-butylphenyl) phosphite, and terphenyl phosphite. Ester, distearyl pentaerythritol diphosphite, di(2,4-di-tert-butylphenyl) pentaerythritol diphosphite, di(nonylphenyl) pentaerythritol diphosphite, phenyl bisphenol A pentaerythritol diphosphite, tetra(tridecyl)-4,4'-butylidene bis(3-methyl-6-tert-butylphenol) diphosphite, hexa(tridecyl)-1,1,3-tri(2-methyl-4-hydroxy-5-tert-butylphenyl) butane triphosphite, 3,5-di-tert-butyl-4-hydroxybenzyl phosphate diethyl ester, bis(4-tert-butylphenyl) phosphate sodium salt, 2,2'-methylene-bis(4,6-di-tert-butylphenyl) phosphate sodium salt, 1,3-bis(diphenoxyphosphoryloxy)benzene, etc.

[0204] Examples of the polymerization inhibitor as a sulfur-containing compound include diphenyl sulfide, phenothiazine, 3-oxophenothiazine, 5-oxophenothiazine, phenothiazine dimer, 1,4-dimercaptobenzene, 1,2-dimercaptobenzene, 2-mercaptophenol, 4-mercaptophenol, 2-(methylthio)phenol, and 3,7-bis(dimethylamino)phenothiazine. Chloride, sulfur (elemental), etc.

[0205] Examples of the polymerization inhibitor as an iron-containing compound include iron (III) chloride and the like.

[0206] Examples of the polymerization inhibitor as a copper compound include copper dimethyldithiocarbamate, copper diethyldithiocarbamate, copper dibutyldithiocarbamate, copper salicylate, copper acetate, copper thiocyanate, copper nitrate, copper chloride, copper carbonate, copper hydroxide, copper acrylate, copper methacrylate, and the like.

[0207] Examples of the polymerization inhibitor as a manganese-containing compound include manganese dialkyldithiocarbamate (the alkyl group is any of methyl, ethyl, propyl and butyl, and may be the same or different), manganese diphenyldithiocarbamate, manganese formate, manganese acetate, manganese octoate, manganese naphthenate, manganese permanganate, and manganese salt of ethylenediaminetetraacetic acid.

[0208] Among the above, from the viewpoint of quality stability of the composition containing methacrylic acid during storage, as component B, at least one polymerization inhibitor selected from phenolic compounds, N-oxyl radical compounds, amine compounds, phosphorus-containing compounds and sulfur-containing compounds is preferred, for example, at least one polymerization inhibitor selected from hydroquinone, 4-methoxyphenol, 2,4-dimethyl-6-tert-butylphenol, 2,6-di-tert-butyl-4-methylphenol, 4-hydroxy-2,2,6,6-tetramethylpiperidinyl-N-oxyl radical, N,N-diphenylamine, N-nitrosodiphenylamine, triphenyl phosphite and phenothiazine is preferred. Component B is more preferably a phenolic compound, for example, at least one polymerization inhibitor selected from hydroquinone, 4-methoxyphenol, 2,4-dimethyl-6-tert-butylphenol and 2,6-di-tert-butyl-4-methylphenol is more preferred. Component B is more preferably a phenolic compound, and for example, is more preferably at least one polymerization inhibitor selected from the group consisting of hydroquinone and 4-methoxyphenol.

[0209] Component B may be one kind or two or more kinds.

[0210] When the composition containing methacrylic acid contains a compound corresponding to both component A21 and component B, the compound is regarded as component B. That is, the composition containing methacrylic acid needs to contain component A21 different from the compound. When two or more compounds corresponding to both component A21 and component B are contained, the compound with the highest molar concentration in the composition containing methacrylic acid is regarded as component B, and the other compounds are regarded as component A21.

[0211] (Concentrations of Component A21 and Component B)

[0212] The concentration of component A21 is M A21 (μmol / L), the concentration of component B is M B (μmol / L), from the perspective of inhibiting pyruvic acid production, M B / M A21 It is preferably 0.005 to 100, more preferably 0.01 to 80, further preferably 0.05 to 60, and particularly preferably 0.1 to 40.

[0213] M A21 It is preferably 1 to 50000 μmol / L. A21 When the concentration of M is 1 μmol / L or more, the effect of inhibiting the decomposition of the polymerization inhibitor can be fully obtained. A21 When the concentration is 50000 μmol / L or less, the amount of impurities in producing a methacrylic acid polymer by polymerizing the methacrylic acid-containing composition of the second embodiment can be reduced, thereby preventing adverse effects on the physical properties of the polymer. A21 The lower limit of M is more preferably 10 μmol / L or more, further preferably 30 μmol / L or more, particularly preferably 50 μmol / L or more, and even more preferably 60 μmol / L or more. A21 The upper limit is more preferably 30000 μmol / L or less, further preferably 10000 μmol / L or less, particularly preferably 5000 μmol / L or less, still more preferably 2500 μmol / L or less, and most preferably 500 μmol / L or less.

[0214] M B It is preferably 1 to 50000 μmol / L. B When the concentration of M is 1 μmol / L or more, the effect of inhibiting the decomposition of the polymerization inhibitor can be fully obtained. B When the concentration is 50000 μmol / L or less, the amount of impurities in producing a methacrylic acid polymer by polymerizing the methacrylic acid-containing composition of the second embodiment can be reduced, thereby preventing adverse effects on the physical properties of the polymer. BThe lower limit of is more preferably 10 μmol / L or more, further preferably 100 μmol / L or more, particularly preferably 1000 μmol / L or more, even more preferably 1500 μmol / L or more, and most preferably 2000 μmol / L or more. B The upper limit is more preferably 10000 μmol / L or less, further preferably 5000 μmol / L or less, particularly preferably 3000 μmol / L or less, and particularly preferably 2500 μmol / L or more.

[0215] (Methacrylic acid concentration)

[0216] The concentration of methacrylic acid in the methacrylic acid-containing composition of the second embodiment is 98.00 to 99.99% by mass in the first embodiment. When the concentration of methacrylic acid is 98.00% by mass or more, the amount of impurities when producing a methacrylic acid polymer by polymerization of the methacrylic acid-containing composition of the second embodiment can be reduced, and the physical properties of the polymer can be prevented from being adversely affected. In addition, by making the concentration of methacrylic acid 99.99% by mass or less, the purification cost can be reduced. The lower limit of the concentration of methacrylic acid is more preferably 98.50% or more, further preferably 99.00% or more, particularly preferably 99.50% or more, and most preferably 99.80% or more by mass.

[0217] (Ingredient C)

[0218] The first embodiment of the methacrylic acid-containing composition of the second aspect may further contain component C as another compound as long as the concentration of methacrylic acid is 98.00 to 99.99% by mass. Component C includes impurities generated in the production process of methacrylic acid. For example, methacrylic acid may contain diacetyl as an impurity. From the viewpoint of reducing the coloration of the methacrylic acid-containing composition, the concentration of diacetyl is preferably 55 μmol / L or less, more preferably 20 μmol / L or less, further preferably 10 μmol / L or less, and particularly preferably 1 μmol / L or less.

[0219] (Analysis of Compositions Containing Methacrylic Acid)

[0220] The fact that the composition containing methacrylic acid contains component A21, component B, component C, and water can be confirmed by, for example, GC-MS measurement. In the GC-MS spectrum of the composition containing methacrylic acid, if there is a peak at the same retention time as the standard of component A21, and the m / z value detected in the mass spectrum of the peak is consistent with the accurate mass of component A21, it can be determined that the composition containing methacrylic acid contains component A21. In the case where a standard of component A21 is not available, when the pattern of the mass spectrum of the peak appearing in the GC-MS spectrum of the composition containing methacrylic acid is consistent with the pattern of the mass spectrum of component A21 included in the mass spectrum database, it can be determined that the peak is the peak of component A21. That is, it can be determined that the composition containing methacrylic acid contains component A21. Examples of mass spectrum databases include NIST20, NIST17, NIST14, and NIST14s. In addition, when the volatility is low and cannot be detected by GC-MS measurement, LC-MS can be used for detection. Component B, component C, and water can also be confirmed by the same method as that of component A1.

[0221] In addition, the concentration of methacrylic acid can be calculated by, for example, performing GC-FID measurement on a composition containing methacrylic acid, quantifying it using the area percentage method, and correcting it using the amount of water quantified by a Karl Fischer titrator. The concentration of component A21 can be quantified by, for example, performing GC measurement on a composition containing methacrylic acid and using an internal standard method. If a standard product of component A21 is not available and quantification cannot be performed using the internal standard method, an organic compound with a known concentration can be subjected to GC-FID measurement under the same conditions as the composition containing methacrylic acid, and the concentration of component A21 can be calculated using the following formula.

[0222]

[0223] Here, N is the number of carbon atoms in one molecule of an organic compound of known concentration. A21 is the number of carbon atoms in one molecule of component A21, S A21 is the peak area of ​​component A21, S is the peak area of ​​the organic compound of known concentration, and M is the concentration (μmol / L) of the organic compound of known concentration.

[0224] When volatility is low and quantification by GC is not possible, quantification can be performed by chromatography such as LC.

[0225] The concentrations of Component B and Component C can also be calculated by the same method as that of Component A21 described above.

[0226] In addition, the fact that the composition containing methacrylic acid contains water and the concentration of water can be confirmed by Karl Fischer method.

[0227] (ingredient B)

[0228] In the second embodiment of the second aspect, the methacrylic acid-containing composition preferably contains component B. Preferred embodiments of component B are the same as those of the first embodiment. Component B may be one type or two or more types.

[0229] (Concentration of ingredient B)

[0230] M B The preferred embodiment is the same as that of the first embodiment.

[0231] (Methacrylic acid concentration)

[0232] The preferred concentration of methacrylic acid is the same as that in the first embodiment.

[0233] (Ingredient C)

[0234] The details and preferred aspects of component C are the same as those of the first embodiment.

[0235] (Analysis of Compositions Containing Methacrylic Acid)

[0236] The method of confirming that the composition containing methacrylic acid contains component B, component C, and water, and the method of measuring the concentrations of methacrylic acid, component B, component C, and water are the same as those in the first embodiment.

[0237] [Method for producing a composition containing methacrylic acid]

[0238] As a second method for producing a composition containing methacrylic acid, there can be mentioned a method of adding component A21 and, if necessary, component B to methacrylic acid. Methacrylic acid can use a commercial product, or methacrylic acid produced by a known method such as the acetone cyanohydrin (ACH) method or the C4 direct oxidation method. Component A21 and component B can use a commercial product, or a compound synthesized by a known method. In the case of using a substance produced by a known method such as the acetone cyanohydrin (ACH) method or the C4 direct oxidation method for methacrylic acid, component A21 or component B can be added midway in the process of the raw material or the manufacturing process to produce a composition containing methacrylic acid. In addition, in the case where component A21 or component B is generated as a by-product in the methacrylic acid manufacturing process, a composition containing methacrylic acid can also be produced by leaving a portion of the generated component A21 or component B.

[0239] [Evaluation method of storage stability and thermal stability]

[0240] The second embodiment has high quality stability of the composition containing methacrylic acid during storage. As an evaluation method for the quality stability of the composition containing methacrylic acid during storage, for example, a method of actually storing the composition containing methacrylic acid for a long time and confirming the reduction in the amount of the polymerization inhibitor can be cited. In addition, from the perspective of simplicity of operation, a method of heating the composition containing methacrylic acid for a short time and confirming the reduction in the amount of the polymerization inhibitor can be used. When heating for a short time, the heating temperature is preferably 50 to 100°C, and the heating time is preferably 1 to 24 hours. In the present invention, the quality stability of the composition containing methacrylic acid during storage is evaluated based on the reduction in the amount of the polymerization inhibitor when the composition containing methacrylic acid is stored at 25°C for 21 days.

[0241] [Method for producing methacrylate]

[0242] The method for producing a methacrylic acid ester of the second embodiment includes a step of esterifying the methacrylic acid-containing composition of the second embodiment.

[0243] The alcohol to be reacted with the composition containing methacrylic acid is not particularly limited, and examples thereof include methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, and the like. Examples of the methacrylic acid esters obtained include methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, butyl methacrylate, and isobutyl methacrylate. The esterification reaction may be carried out in the presence of an acidic catalyst such as a sulfonic acid type cation exchange resin. The temperature in the esterification reaction is preferably 50 to 200°C.

[0244] The pressure during the esterification reaction, the position of the catalyst in the reactor, the ratio of the catalyst in the reactor, and the like are not particularly limited, and commonly used methods can be applied.

[0245] [Method for producing methacrylic acid polymer according to the second aspect]

[0246] The method for producing a methacrylic acid polymer of the second embodiment includes a step of polymerizing a polymerizable composition containing the methacrylic acid-containing composition of the second embodiment.

[0247] The polymerizable composition may contain a monomer copolymerizable with methacrylic acid and other additives as necessary.

[0248] Examples of the monomer copolymerizable with methacrylic acid include the following monomers: methacrylic acid esters such as methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, 2-ethylhexyl methacrylate, phenyl methacrylate, or benzyl methacrylate;

[0249] Acrylates such as methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, tert-butyl acrylate, or 2-ethylhexyl acrylate;

[0250] Unsaturated carboxylic acids such as acrylic acid, maleic acid, or itaconic acid;

[0251] Unsaturated carboxylic anhydrides such as maleic anhydride or itaconic anhydride;

[0252] Maleimides such as N-phenylmaleimide or N-cyclohexylmaleimide;

[0253] A vinyl monomer containing a hydroxyl group, such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, or 2-hydroxypropyl methacrylate;

[0254] Vinyl esters such as vinyl acetate or vinyl benzoate;

[0255] Vinyl chloride, vinylidene chloride and their derivatives;

[0256] Nitrogen-containing vinyl monomers such as methacrylamide or acrylonitrile;

[0257] Monomers containing epoxy groups such as glycidyl acrylate or glycidyl methacrylate;

[0258] Aromatic vinyl monomers such as styrene or α-methylstyrene;

[0259] Alkanediol di(meth)acrylates such as ethylene glycol di(meth)acrylate, 1,2-propylene glycol di(meth)acrylate, 1,3-butylene glycol di(meth)acrylate, or 1,6-hexanediol di(meth)acrylate;

[0260] Polyoxyalkylene glycol di(meth)acrylates such as diethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, triethylene glycol (meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, or neopentyl glycol di(meth)acrylate;

[0261] Vinyl monomers having two or more ethylenically unsaturated bonds in the molecule, such as divinylbenzene;

[0262] An unsaturated polyester prepolymer obtained from at least one polycarboxylic acid including an ethylenically unsaturated polycarboxylic acid and at least one diol;

[0263] A vinyl ester prepolymer obtained by modifying the epoxy group terminal with acrylic acid.

[0264] Among the above, the monomer copolymerizable with methacrylic acid is preferably at least one selected from methacrylic acid esters and acrylates. The monomer copolymerizable with methacrylic acid is more preferably methacrylic acid ester, and particularly preferably methyl methacrylate.

[0265] The monomer copolymerizable with methacrylic acid may be one or more. In addition, when component A21 is a monomer copolymerizable with methacrylic acid, component A21 may be used as a monomer copolymerizable with methacrylic acid, or a monomer copolymerizable with methacrylic acid different from component A21 may be used.

[0266] In the polymerizable composition, the content of the monomer copolymerizable with methacrylic acid is preferably 50.00 to 99.99 parts by mass relative to 100 parts by mass of the polymerizable composition. The lower limit of the content of the monomer copolymerizable with methacrylic acid is more preferably 60 parts by mass or more, further preferably 70 parts by mass or more, particularly preferably 80 parts by mass or more, and most preferably 90 parts by mass or more, relative to 100 parts by mass of the polymerizable composition. The upper limit of the content of the monomer copolymerizable with methacrylic acid is more preferably 99.9 parts by mass or less, further preferably 99 parts by mass or less, relative to 100 parts by mass of the polymerizable composition.

[0267] As other additives, polymerization initiators are preferred. In addition, the polymerizable composition may further contain chain transfer agents, mold release agents, lubricants, plasticizers, antioxidants, antistatic agents, light stabilizers, ultraviolet absorbers, flame retardants, flame retardant aids, polymerization inhibitors, fillers, pigments, dyes, silane coupling agents, leveling agents, defoamers, fluorescent agents, etc. as needed. Other additives may be one or more.

[0268] As a polymerization initiator, the following polymerization initiators are mentioned, for example.

[0269] Azo compounds such as 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), 2,2'-azobis(2-methylpropionitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2,4,4-trimethylpentane), 2,2'-azobis(2-methylpropane), 1,1-azobis(cyclohexanecarbonitrile), and 2,2'-azobisisobutyric acid dimethyl ester;

[0270] Benzoyl peroxide, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, 1,1-bis(tert-butylperoxy)cyclohexane, 1,1-bis(tert-butylperoxy)-3,5,5-trimethylcyclohexane, tert-butyl peroxy-2-ethylhexanoate, tert-butyl peroxyisobutyrate, tert-butyl peroxybenzoate, tert-hexyl peroxybenzoate, tert-butyl peroxyisopropyl monocarbonate, tert-butyl peroxy-3,5,5-trimethylhexanoate, tert-butyl peroxylaurate, tert-butyl peroxyacetate, tert-hexyl peroxyisopropyl monocarbonate, tert-ethyl peroxy Organic peroxides such as tert-hexyl hexanoate, tert-amyl peroxy-2-ethylhexanoate, 1,1,3,3-tetramethylbutyl peroxyethylhexanoate, 1,1,2-trimethylpropyl peroxy-2-ethylhexanoate, 1,1,3,3-tetramethylbutyl peroxyisopropyl monocarbonate, 1,1,2-trimethylpropyl peroxyisopropyl monocarbonate, 1,1,3,3-tetramethylbutyl peroxyisononanoate, 1,1,2-trimethylpropyl peroxy-isononanoate, di-tert-butyl peroxide, di-tert-hexyl peroxide, lauroyl peroxide, and dilauroyl peroxide;

[0271] Persulfate compounds such as potassium persulfate;

[0272] Redox polymerization initiator.

[0273] Among the above, the polymerization initiator is preferably at least one selected from azo compounds and organic peroxides from the viewpoint of storage stability and reactivity of methacrylic acid with a copolymerizable monomer.

[0274] The amount of the polymerization initiator used is preferably 0.0001 to 1 part by mass based on 100 parts by mass of the total of methacrylic acid and the monomer copolymerizable with methacrylic acid.

[0275] Examples of the polymerization method for the polymerizable composition include bulk polymerization, solution polymerization, emulsion polymerization, and suspension polymerization.

[0276] The polymerization temperature is preferably 125 to 210° C. This allows for an appropriate polymerization rate. More preferably, the lower limit of the polymerization temperature is 130° C. or higher and the upper limit is 180° C. or lower. The polymerization time is not particularly limited and may be, for example, 0.5 to 24 hours.

[0277] [Methacrylic acid-containing composition of the third aspect]

[0278] The methacrylic acid-containing composition of the third embodiment contains methacrylic acid and a compound represented by the following formula (31), namely, component A3. The concentration of methacrylic acid is 98.00 to 99.99% by mass.

[0279]

[0280] In formula (31), R 1c , R 2c , R 3c , R 4c , R 5c , R 6c and R 7c Each of the groups independently represents a hydrogen atom, an alkyl group, an alkenyl group, an aryl group, a hydroxyl group, an alkoxy group, an amino group, a monovalent group including a carbonyl group, an alkylthio group or an arylthio group.

[0281] The methacrylic acid-containing composition may contain a polymerization inhibitor (component B), other compounds (component C), and water as long as the methacrylic acid concentration satisfies 98.00 to 99.99% by mass.

[0282] (Methacrylic acid)

[0283] The methacrylic acid-containing composition of the third embodiment contains methacrylic acid. Methacrylic acid can be produced, for example, as a byproduct of the acetone cyanohydrin (ACH) method or as an intermediate of the C4 direct oxidation method. The methacrylic acid contained in the methacrylic acid-containing composition is preferably produced by the C4 direct oxidation method, and more preferably produced by the C4 direct oxidation method using biomass-derived isobutanol as a starting material.

[0284] (ingredient A3)

[0285] The methacrylic acid-containing composition of the third embodiment contains the compound (component A3) represented by the above formula (31). Since the methacrylic acid-containing composition contains component A3, decomposition of the polymerization inhibitor during storage of the methacrylic acid-containing composition can be suppressed. The reason for this is presumed to be as follows.

[0286] It is known that methacrylic acid will polymerize due to free radicals generated during storage, and an inhibitor (component B) is added to prevent polymerization. Component B has an anti-polymerization function by capturing free radicals generated during the storage of methacrylic acid, but since the inhibitor decomposes into other compounds when capturing free radicals, the concentration of component B in the composition containing methacrylic acid during storage slowly decreases, resulting in a slow decrease in the anti-polymerization function. In addition, the unwanted decomposition products generated by component B capturing free radicals slowly increase. As an example of free radicals generated during the storage of methacrylic acid, hydroxyl radicals generated by oxygen molecules absorbing ultraviolet light from sunlight can be cited. Component A3 absorbs ultraviolet light because it is a π-conjugated system compound having a benzene ring, and its absorption wavelength varies depending on the type of substituent. Component A3 can absorb ultraviolet light in a wide range of wavelengths. Therefore, when a composition containing methacrylic acid contains component A3, ultraviolet light in a wide range of wavelengths is absorbed to suppress the generation of hydroxyl radicals. Therefore, the free radicals that component B needs to capture are reduced, thereby suppressing the reduction in the concentration of component B and the generation of decomposition products.

[0287] The molecular weight of component A3 is preferably 2000 or less. By making the molecular weight 2000 or less, the number of benzene rings per unit mass in component A3 can be increased, so the effect of the present invention can be obtained with less mass. The molecular weight of component A3 is more preferably 1600 or less, further preferably 1200 or less, and particularly preferably 800 or less.

[0288] R in formula (31) 1c , R 2c , R 3c , R 4c , R 5c , R 6c and R 7c R independently represents a hydrogen atom, an alkyl group, an alkenyl group, an aryl group, a hydroxyl group, an alkoxy group, an amino group, a monovalent group including a carbonyl group, an alkylthio group or an arylthio group. 1c , R 2c , R 3c , R 4c , R 5c , R 6c and R 7c Can be the same or different.

[0289] R 1c , R 2c , R 3c , R 4c , R 5c , R 6c and R 7cWhen the above conditions are met, the π conjugated system of component A3 can be maintained, and ultraviolet light of a wide range of wavelengths can be absorbed, thereby suppressing the generation of hydroxyl radicals and obtaining the effect of the present invention. From the perspective of increasing the absorbance of ultraviolet light and suppressing the generation of hydroxyl radicals, R 1c , R 2c , R 3c , R 4c , R 5c , R 6c and R 7c Preferred are a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, an aryl group having 6 to 12 carbon atoms, a hydroxyl group, an alkoxy group having 1 to 6 carbon atoms, an amino group having 0 to 6 carbon atoms, or a monovalent group containing a carbonyl group having 1 to 6 carbon atoms; more preferred are a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, a hydroxyl group, an alkoxy group having 1 to 5 carbon atoms, a carboxyl group, or an alkoxycarbonyl group having 2 to 6 carbon atoms; further preferred are a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, and a hydroxyl group; further preferred are a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, an isobutyl group, a tert-butyl group, and a hydroxyl group; particularly preferred are a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, and a hydroxyl group; and most preferred are a hydrogen atom, a methyl group, and a hydroxyl group.

[0290] The alkyl group is a chain (straight or branched) alkyl group or a cyclic alkyl group. Preferably, it is an alkyl group having 1 to 20 carbon atoms, more preferably an alkyl group having 1 to 10 carbon atoms, and further preferably an alkyl group having 1 to 5 carbon atoms. As chain alkyl groups, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, hexyl, octyl, decyl, hydroxymethyl, 1-hydroxyethyl, 2-hydroxyethyl, etc. can be mentioned, preferably methyl, ethyl, n-propyl, isopropyl. In addition, as cyclic alkyl groups, for example, cyclopentyl, cyclohexyl, cyclooctyl, etc. can be mentioned.

[0291] The alkenyl group is a chain (straight or branched) alkenyl group or a cyclic alkenyl group. Preferably, the alkenyl group has 2 to 20 carbon atoms, more preferably, the alkenyl group has 2 to 10 carbon atoms, and further preferably, the alkenyl group has 2 to 5 carbon atoms. Examples of chain alkenyl groups include vinyl, 1-propenyl, isopropenyl, 2-butenyl, 1,3-butadienyl, 2-pentenyl, and 2-hexenyl. In addition, examples of cyclic alkenyl groups include cyclopentenyl and cyclohexenyl.

[0292] The aryl group is preferably an aryl group having 1 to 20 carbon atoms, and more preferably an aryl group having 1 to 12 carbon atoms. The aryl group includes a heteroaryl group containing oxygen, nitrogen, sulfur, and the like. Examples of the aryl group include phenyl, mesityl, naphthyl, 2-methylphenyl, 3-methylphenyl, 4-methylphenyl, 2,3-dimethylphenyl, 2,4-dimethylphenyl, 2,5-dimethylphenyl, 2,6-dimethylphenyl, 2-ethylphenyl, isothiophenyl, 2-thiophenyl, 2-ethylphenyl, 2-isothio ... Azolyl, isothiazolyl, imidazolyl, oxazolyl, thiazolyl, thiadiazolyl, thienyl, triazolyl, tetrazolyl, pyridyl, pyrazinyl, pyrimidinyl, pyridazinyl, pyrazolyl, pyrrolyl, furanyl, furazanyl, isoquinolyl, isoindolyl, indolyl, quinolyl, pyridothiazolyl, benzimidazolyl, benzo oxazolyl, benzothiazolyl, benzotriazolyl, benzofuranyl, imidazopyridinyl, triazolopyridinyl, purinyl.

[0293] The alkoxy group is preferably an alkoxy group having 1 to 20 carbon atoms, more preferably an alkoxy group having 1 to 10 carbon atoms, and still more preferably an alkoxy group having 1 to 6 carbon atoms. Examples of the alkoxy group include methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, sec-butoxy, tert-butoxy, n-pentoxy, isopentoxy, and phenoxy.

[0294] Amino groups include amino groups with no substituent on the nitrogen atom (-NH 2 ) (carbon number 0), and an amino group in which a part or all of the hydrogen atoms bonded to the nitrogen atom are substituted with carbon atoms. The number of carbon atoms of the amino group in which a part or all of the hydrogen atoms bonded to the nitrogen atom are substituted with carbon atoms is preferably 1 to 20, more preferably 1 to 10, and further preferably 1 to 6. Examples of the amino group include an unsubstituted amino group (—NH 2 ), methylamino, ethylamino, propylamino, butylamino, dimethylamino, diethylamino, aniline, toluidine, anisidine, diphenylamino, N-methyl-N-phenylamino, etc.

[0295] Examples of the monovalent group containing a carbonyl group include a formyl group, an acyl group, a carboxyl group, an amide group, an alkoxycarbonyl group, a thiocarboxyl group, and a thioester group. A monovalent group containing a carbonyl group having 1 to 6 carbon atoms is preferred.

[0296] The acyl group is a substituent formed by connecting a carbonyl group to an alkyl group, an alkenyl group, or an aryl group. The total number of carbon atoms (1) derived from the carbonyl group and the number of carbon atoms derived from the alkyl group, the alkenyl group, or the aryl group is preferably 2 to 20, more preferably 2 to 10, and even more preferably 2 to 6. Examples of the acyl group include acetyl, propionyl, butyryl, vinylcarbonyl, and benzoyl.

[0297] The amide group includes an amide group with no substituent on the nitrogen atom (-CONH 2 ), and an amide group in which a part or all of the hydrogen atoms bonded to the nitrogen atom are substituted with carbon atoms. The number of carbon atoms in the amide group is preferably 1 to 20, more preferably 1 to 10, and even more preferably 1 to 5, based on the total number of carbon atoms from the carbonyl group (1) and the number of carbon atoms substituted on the nitrogen atom. Examples of the amide group include an unsubstituted amide group, an N-methylamide group, an N-ethylamide group, an N-phenylamide group, an N,N-dimethylamide group, and an N-methyl-N-phenylamide group.

[0298] The alkoxycarbonyl group is a substituent formed by connecting a carbonyl group to an alkoxy group, and is also called an ester group. The total number of carbon atoms (1) derived from the carbonyl group and the number of carbon atoms derived from the alkoxy group is preferably 2 to 20, more preferably 2 to 10, and further preferably 2 to 6. Examples of the alkoxycarbonyl group include methoxycarbonyl, ethoxycarbonyl, butoxycarbonyl, and phenoxycarbonyl.

[0299] The thioester group is a substituent formed by connecting a carbonyl group to an alkylthio group or an arylthio group. The total number of carbon atoms (1) derived from the carbonyl group and the number of carbon atoms derived from the alkylthio group or the arylthio group is preferably 2 to 20, more preferably 2 to 10, and further preferably 2 to 6. Examples of the thioester group include methylthiocarbonyl, ethylthiocarbonyl, butylthiocarbonyl, and phenylthiocarbonyl.

[0300] In addition, the monovalent group containing a carbonyl group may be a substituent in which one or more hydrogen atoms of an alkyl group are replaced by a carbonyl group. Examples of such a substituent include 2-acetoxyethyl, 2-acetylethyl, and 2-(acetoacetoxy)ethyl.

[0301] The alkylthio group is preferably an alkylthio group having 1 to 20 carbon atoms, more preferably an alkylthio group having 1 to 10 carbon atoms, and further preferably an alkylthio group having 1 to 5 carbon atoms. Examples of the alkylthio group include methylthio, ethylthio, propylthio, and isopropylthio.

[0302] The arylthio group is preferably an arylthio group having 1 to 20 carbon atoms, more preferably an arylthio group having 3 to 10 carbon atoms, and further preferably an arylthio group having 6 to 10 carbon atoms. Examples of the arylthio group include a phenylthio group and a tolylthio group.

[0303] Among the compounds satisfying the above conditions, from the viewpoint of quality stability of the methacrylic acid-containing composition during storage, preferred as component A3 are tert-butylphenyl ether, isopropylphenyl ether, 1-isopropoxy-3-methylbenzene, 4-isopropoxyphenol, 1-tert-butoxy-4-methylbenzene, 2-(2,4-dimethyl-6-tert-butylphenoxy)-2-methylpropionic acid, 2-(2,6-di-tert-butyl-4-methylphenoxy)-2-methylpropionic acid, 2-(4-methoxyphenoxy)-2-methylpropionic acid, 2-(4-hydroxyphenoxy)-2-methylpropionic acid, 2 The tert-butylphenyl ether is preferably tert-butylphenyl ether, isopropylphenyl ether, 1-isopropoxy-3-methylbenzene, 4-isopropoxyphenol, or 2-(4-methoxyphenoxy)-2-methylpropionic acid methyl ester, and the tert-butylphenyl ether and 2-(4-methoxyphenoxy)-2-methylpropionic acid methyl ester are more preferably tert-butylphenyl ether, isopropylphenyl ether, 1-isopropoxy-3-methylbenzene, 4-isopropoxyphenol, or 2-(4-methoxyphenoxy)-2-methylpropionic acid.

[0304] Component A3 may be one kind or two or more kinds.

[0305] (ingredient B)

[0306] The composition containing methacrylic acid in the third embodiment preferably contains an inhibitor (component B). In the present specification, an inhibitor refers to a compound having the function of inhibiting the polymerization reaction of methacrylic acid. As inhibitors, for example, phenolic compounds, quinone compounds, nitrobenzene compounds, N-oxy radical compounds, amine compounds, phosphorus-containing compounds, sulfur-containing compounds, iron-containing compounds, copper-containing compounds and manganese-containing compounds can be cited. By containing component B, the polymerization reaction of methacrylic acid based on the free radical polymerization mechanism during the storage of methacrylic acid can be inhibited. In addition, component B can capture the above-mentioned hydroxyl radicals generated during the storage of methacrylic acid. That is, when the composition containing methacrylic acid contains component B in addition to component A3, the amount of hydroxyl radicals can be reduced by the following two different mechanisms, that is, the generation of hydroxyl radicals can be inhibited by component A3, and the generated hydroxyl radicals can be removed by component B. Therefore, it is believed that the reduction of component B and the generation of decomposition products can be efficiently inhibited.

[0307] Examples of the polymerization inhibitor as a phenolic compound include alkylphenols, hydroxyphenols, aminophenols, nitrophenols, nitrosophenols, alkoxyphenols, and tocopherol.

[0308] Examples of the alkylphenol include o-cresol, m-cresol, p-cresol, 2-tert-butyl-4-methylphenol, 2,4-dimethyl-6-tert-butylphenol, 2,6-di-tert-butyl-4-methylphenol, 2-tert-butylphenol, 4-tert-butylphenol, 2,4-di-tert-butylphenol, 2-methyl-4-tert-butylphenol, 4-tert-butyl-2,6-dimethylphenol, 2,2′-methylenebis(4-ethyl-6-tert-butylphenol), 4,4′-thiobis(3-methyl-6-tert-butylphenol), and 3,5-di-tert-butyl-4-hydroxytoluene.

[0309] Examples of the hydroxyphenol include hydroquinone, 2-methylhydroquinone, 2-tert-butylhydroquinone, 2,5-di-tert-butylhydroquinone, 2,6-di-tert-butylhydroquinone, 2,5-di-tert-amylhydroquinone, 2-tert-butylmethoxyhydroquinone, 2,3,5-trimethylhydroquinone, 2,5-dichlorohydroquinone, 1,2-dihydroxybenzene, 2-acetylhydroquinone, 4-methylcatechol, 4-tert-butylcatechol, 2-methylresorcinol, 4-methylresorcinol, and 2,3-dihydroxyacetophenone.

[0310] Examples of the aminophenol include o-aminophenol, m-aminophenol, p-aminophenol, 2-(N,N-dimethylamino)phenol, and 4-(ethylamino)phenol.

[0311] Examples of the nitrophenol include o-nitrophenol, m-nitrophenol, p-nitrophenol, and 2,4-dinitrophenol.

[0312] Examples of the nitrosophenol include o-nitrosophenol, m-nitrosophenol, p-nitrosophenol, and α-nitroso-β-naphthol.

[0313] Examples of the alkoxyphenol include 2-methoxyphenol, 2-ethoxyphenol, 2-isopropoxyphenol, 2-tert-butoxyphenol, 4-methoxyphenol, 4-ethoxyphenol, 4-propoxyphenol, 4-butoxyphenol, 4-tert-butoxyphenol, 4-heptyloxyphenol, hydroquinone monobenzyl ether, tert-butyl-4-methoxyphenol, di-tert-butyl-4-methoxyphenol, pyrogallol-1,2-dimethyl ether, and hydroquinone monobenzoate.

[0314] Examples of the tocopherol include α-tocopherol and 2,3-dihydro-2,2-dimethyl-7-hydroxybenzofuran.

[0315] Examples of the polymerization inhibitor as a quinone compound include p-benzoquinone, chloro-p-benzoquinone, 2,5-dichloro-p-benzoquinone, 2,6-dichloro-p-benzoquinone, tetrachloro-p-benzoquinone, tetrabromo-p-benzoquinone, 2,3-dimethyl-p-benzoquinone, 2,5-dimethyl-p-benzoquinone, methoxy-p-benzoquinone, and methyl-p-benzoquinone.

[0316] Examples of the polymerization inhibitor as a nitrobenzene compound include nitrobenzene, o-dinitrobenzene, m-dinitrobenzene, p-dinitrobenzene, 2,4-dinitrobenzene, dinitrodurene, and 2,2-diphenyl-1-picrylhydrazyl.

[0317] Examples of the polymerization inhibitor as an N-oxyl radical compound include 4-hydroxy-2,2,6,6-tetramethyl-piperidin-N-oxyl radical, 4-oxo-2,2,6,6-tetramethyl-piperidin-N-oxyl radical, 4-acetoxy-2,2,6,6-tetramethyl-piperidin-N-oxyl radical, 2,2,6,6-tetramethyl-piperidin-N-oxyl radical, piperidine-1-oxyl radical, 4-(dimethylamino)-2,2,6,6-tetramethyl-piperidin-N-oxyl radical, 4-amino-2,2,6,6-tetramethyl-piperidin-N-oxyl radical, 4-vinyloxy-2,2,6,6-tetramethyl-piperidin-N-oxyl radical, 4-benzoyloxy-2,2,6,6-tetramethyl-piperidin-N-oxyl radical, -N-oxyl free radical, 2,2,5,5-tetramethyl-piperidinyl-N-oxyl free radical, 3-amino-2,2,5,5-tetramethyl-piperidinyl-N-oxyl free radical, 4,4',4"-tris(2,2,6,6-tetramethyl-piperidinyl-N-oxyl free radical)phosphite, 3-oxo-2,2,5,5-tetramethylpyrrolidine-N-oxyl free radical, pyrrolidine-1-oxyl free radical, 2,2,5,5-tetramethyl-1-oxa-3-azacyclopentyl-3-oxyl free radical, 2,2,5,5-tetramethyl-3-pyrrolinyl-1-oxyl-3-carboxylic acid, 2,2,3,3,5,5,6,6-octamethyl-1,4-diazacyclohexyl-1,4-dioxyl free radical, di-tert-butylnitroxide, di-tert-amylnitroxide, etc.

[0318] Examples of the polymerization inhibitor as an amine compound include N,N-diphenylamine, alkylated diphenylamine, 4,4'-dicumyldiphenylamine, 4,4'-dioctyldiphenylamine, 4-aminodiphenylamine, p-nitrosodiphenylamine, N-nitrosodinaphthylamine, N-nitrosodiphenylamine, N-nitrosophenylnaphthylamine, N-nitrosophenylhydroxylamine, N,N'-dialkyl-p-phenylenediamine (the alkyl groups may be the same or different, each independently having 1 to 4 carbon atoms, and may be linear or branched), N,N'-diphenyl-p-phenylenediamine, N-phenyl-N'-isopropyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-1,4-phenylenediamine, N,N'-di-2-naphthylamine, 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline, 2,2,4-trimethyl-1,2-dihydroquinoline polymer, butyral-α-naphthylamine, N-phenyl-β-naphthylamine, 4-hydroxy-2,2,6,6-tetramethylpiperidine, 4-benzoyloxy-2,2,6,6-tetramethylpiperidine, 1,4-dihydroxy-2,2,6,6-tetramethylpiperidine, 1-hydroxy-4-benzoyloxy-2,2,6,6-tetramethylpiperidine, etc.

[0319] Examples of the polymerization inhibitor as a phosphorus-containing compound include triphenylphosphine, triphenyl phosphite, triethyl phosphite, tris(isodecyl) phosphite, tris(tridecyl) phosphite, phenyl diisooctyl phosphite, phenyl diisodecyl phosphite, phenyl di(tridecyl) phosphite, diphenyl isooctyl phosphite, diphenyl isodecyl phosphite, diphenyl tridecyl phosphite, [1,1-diphenyl-4,4'-diyl-bis[tetrakis-2,4-bis(1,1-dimethylethyl)phenyl]]phosphonate, tris(nonylphenyl) phosphite, 4,4'-isopropylidene diphenol alkyl phosphite, tris(2,4-di-tert-butylphenyl) phosphite, and terphenyl phosphite. Ester, distearyl pentaerythritol diphosphite, di(2,4-di-tert-butylphenyl) pentaerythritol diphosphite, di(nonylphenyl) pentaerythritol diphosphite, phenyl bisphenol A pentaerythritol diphosphite, tetra(tridecyl)-4,4'-butylidene bis(3-methyl-6-tert-butylphenol) diphosphite, hexa(tridecyl)-1,1,3-tri(2-methyl-4-hydroxy-5-tert-butylphenyl) butane triphosphite, 3,5-di-tert-butyl-4-hydroxybenzyl phosphate diethyl ester, bis(4-tert-butylphenyl) phosphate sodium salt, 2,2'-methylene-bis(4,6-di-tert-butylphenyl) phosphate sodium salt, 1,3-bis(diphenoxyphosphoryloxy)benzene, etc.

[0320] Examples of the polymerization inhibitor as a sulfur-containing compound include diphenyl sulfide, phenothiazine, 3-oxophenothiazine, 5-oxophenothiazine, phenothiazine dimer, 1,4-dimercaptobenzene, 1,2-dimercaptobenzene, 2-mercaptophenol, 4-mercaptophenol, 2-(methylthio)phenol, and 3,7-bis(dimethylamino)phenothiazine. Chloride, sulfur (elemental), etc.

[0321] Examples of the polymerization inhibitor as an iron-containing compound include iron (III) chloride and the like.

[0322] Examples of the polymerization inhibitor as a copper compound include copper dimethyldithiocarbamate, copper diethyldithiocarbamate, copper dibutyldithiocarbamate, copper salicylate, copper acetate, copper thiocyanate, copper nitrate, copper chloride, copper carbonate, copper hydroxide, copper acrylate, copper methacrylate, and the like.

[0323] Examples of the polymerization inhibitor as a manganese-containing compound include manganese dialkyldithiocarbamate (the alkyl group is any of methyl, ethyl, propyl and butyl, and may be the same or different), manganese diphenyldithiocarbamate, manganese formate, manganese acetate, manganese octoate, manganese naphthenate, manganese permanganate, and manganese salt of ethylenediaminetetraacetic acid.

[0324] Among the above, from the viewpoint of quality stability of the composition containing methyl methacrylate during storage, as component B, at least one polymerization inhibitor selected from phenolic compounds, N-oxyl radical compounds, amine compounds, phosphorus-containing compounds and sulfur-containing compounds is preferred, for example, at least one polymerization inhibitor selected from hydroquinone, 4-methoxyphenol, 2,4-dimethyl-6-tert-butylphenol, 2,6-di-tert-butyl-4-methylphenol, 4-hydroxy-2,2,6,6-tetramethylpiperidinyl-N-oxyl radical, N,N-diphenylamine, N-nitrosodiphenylamine, triphenyl phosphite and phenothiazine is preferred. Component B is more preferably a phenolic compound, for example, at least one polymerization inhibitor selected from hydroquinone, 4-methoxyphenol, 2,4-dimethyl-6-tert-butylphenol and 2,6-di-tert-butyl-4-methylphenol is more preferred. Component B is particularly preferably at least one polymerization inhibitor selected from the group consisting of hydroquinone and 4-methoxyphenol.

[0325] Component B may be one kind or two or more kinds.

[0326] When the composition containing methacrylic acid contains a compound corresponding to both component A3 and component B, the compound is regarded as component A3. That is, when the composition containing methacrylic acid contains component A3 and component B, it means that component B different from the compound is contained. When two or more compounds corresponding to both component A3 and component B are contained, the compound with the highest molar concentration in the composition containing methacrylic acid is regarded as component A3, and the other compounds are regarded as component B.

[0327] (Concentration of component A3 and component B)

[0328] The concentration of component A3 is M A3 (μmol / L), the concentration of component B is M B (μmol / L), from the perspective of the efficiency of inhibiting the production of methacrylic acid dimers and pyruvic acid, M B / M A3 It is preferably 0.005-100, more preferably 0.05-10.

[0329] M A3 It is preferably 1 to 50000 μmol / L. A3 When the concentration of M is 1 μmol / L or more, the effect of inhibiting the decomposition of the polymerization inhibitor can be fully obtained. A3 When the concentration is 50000 μmol / L or less, the amount of impurities in producing a methacrylic acid polymer by polymerizing the methacrylic acid-containing composition of the third embodiment can be reduced, thereby preventing adverse effects on the physical properties of the polymer. A3 The lower limit of M is more preferably 10 μmol / L or more, further preferably 30 μmol / L or more, further preferably 50 μmol / L or more, further preferably 55 μmol / L or more, and particularly preferably 60 μmol / L or more. A3 The upper limit is more preferably 25000 μmol / L or less, further preferably 10000 μmol / L or less, and particularly preferably 7500 μmol / L or less.

[0330] M B It is preferably 1 to 50000 μmol / L. B When the concentration of M is 1 μmol / L or more, the effect of inhibiting the production of methacrylic acid dimers and pyruvic acid can be fully obtained. B When the concentration is 50000 μmol / L or less, the amount of impurities in producing a methacrylic acid polymer by polymerizing the methacrylic acid-containing composition of the third embodiment can be reduced, thereby preventing adverse effects on the physical properties of the polymer. BThe lower limit of M is more preferably 10 μmol / L or more, further preferably 100 μmol / L or more, particularly preferably 1500 μmol / L or more, and most preferably 2000 μmol / L or more. B The upper limit is more preferably 45000 μmol / L or less, further preferably 40000 μmol / L or less, particularly preferably 35000 μmol / L or less, even more preferably 30000 μmol / L or less, and most preferably 25000 μmol / L or less.

[0331] (Methacrylic acid concentration)

[0332] The methacrylic acid concentration of the methacrylic acid-containing composition of the third embodiment is 98.00 to 99.99% by mass. When the methacrylic acid concentration is 98.00% by mass or more, the amount of impurities when the methacrylic acid polymer is produced by polymerization of the methacrylic acid-containing composition of the third embodiment can be reduced, and the physical properties of the polymer can be prevented from being adversely affected. In addition, by setting the methacrylic acid concentration to 99.99% by mass or less, the purification cost can be reduced. The lower limit of the methacrylic acid concentration is more preferably 98.50% or more, further preferably 99.00% or more, and particularly preferably 99.50% or more.

[0333] (Ingredient C)

[0334] The composition containing methacrylic acid of the third embodiment may further contain component C as another compound as long as the concentration of methacrylic acid is 98.00 to 99.99% by mass. Examples of component C include impurities generated in the production process of methacrylic acid. For example, methacrylic acid may contain diacetyl as an impurity. From the viewpoint of reducing the coloration of the composition containing methacrylic acid, the concentration of diacetyl is preferably 55 μmol / L or less, more preferably 20 μmol / L or less, further preferably 10 μmol / L or less, and particularly preferably 1 μmol / L or less.

[0335] (Analysis of Compositions Containing Methacrylic Acid)

[0336] The fact that the composition containing methacrylic acid contains component A3, component B, component C, and water can be confirmed by, for example, GC-MS measurement. In the GC-MS spectrum of the composition containing methacrylic acid, if there is a peak at the same retention time as the standard of component A3, and the m / z value detected in the mass spectrum of the peak is consistent with the accurate mass of component A3, it can be determined that the composition containing methacrylic acid contains component A3. In the case where a standard of component A3 cannot be obtained, when the pattern of the mass spectrum of the peak appearing in the GC-MS spectrum of the composition containing methacrylic acid is consistent with the pattern of the mass spectrum of component A3 included in the mass spectrum database, it can be determined that the peak is the component A3 peak. That is, it can be determined that the composition containing methacrylic acid contains component A3. As mass spectrum databases, NIST20, NIST17, NIST14, NIST14s, etc. can be cited. In addition, when the volatility is low and it cannot be detected by GC-MS measurement, LC-MS can be used for detection. Component B, component C, and water can also be confirmed by the same method as component A1.

[0337] In addition, the concentration of methacrylic acid can be calculated by, for example, performing GC-FID measurement on a composition containing methacrylic acid, quantifying it using the area percentage method, and correcting it using the amount of water quantified by a Karl Fischer titrator. The concentration of component A3 can be quantified by, for example, performing GC measurement on a composition containing methacrylic acid and using an internal standard method. If a standard product of component A3 is not available and quantification cannot be performed using the internal standard method, an organic compound with a known concentration can be subjected to GC-FID measurement under the same conditions as the composition containing methacrylic acid, and the concentration of component A3 can be calculated using the following formula.

[0338]

[0339] Here, N is the number of carbon atoms in one molecule of an organic compound with a known concentration. A3 is the number of carbon atoms in one molecule of component A3, S A3 is the peak area of ​​component A3, S is the peak area of ​​the organic compound of known concentration, and M is the concentration (μmol / L) of the organic compound of known concentration.

[0340] When volatility is low and quantification by GC is not possible, quantification can be performed by chromatography such as LC.

[0341] The concentrations of Component B and Component C can also be calculated by the same method as that of Component A3 described above.

[0342] In addition, the presence of water in the composition containing methacrylic acid and the concentration of water can be confirmed by Karl Fischer method.

[0343] [Method for producing a composition containing methacrylic acid]

[0344] As a method for producing a composition containing methacrylic acid in the third embodiment, a method of adding component A3 to methacrylic acid can be cited, and a method of adding component A3 and component B to methacrylic acid can be preferably cited. Methacrylic acid can use a commercial product, or methacrylic acid produced by a known method such as the acetone cyanohydrin (ACH) method and the C4 direct oxidation method. Component A3 and component B can use a commercial product, or a compound synthesized by a known method. In the case of using a substance produced by a known method such as the acetone cyanohydrin (ACH) method and the C4 direct oxidation method for methacrylic acid, component A3 or component B can be added in the middle of the raw material or the production process to produce a composition containing methacrylic acid. In addition, in the case where component A3 or component B is generated as a by-product in the methacrylic acid production process, a composition containing methacrylic acid can be produced by leaving a portion of the generated component A3 or component B.

[0345] [Evaluation method of storage stability and thermal stability]

[0346] The third embodiment has high quality stability of the composition containing methacrylic acid during storage. As an evaluation method for the quality stability of the composition containing methacrylic acid during storage, for example, a method of actually storing the composition containing methacrylic acid for a long time and confirming the reduction in the amount of the polymerization inhibitor can be cited. In addition, from the perspective of simplicity of operation, a method of heating the composition containing methacrylic acid for a short time and confirming the reduction in the amount of the polymerization inhibitor can be used. When heating for a short time, the heating temperature is preferably 50 to 100°C, and the heating time is preferably 1 to 24 hours. In the present invention, the quality stability of the composition containing methacrylic acid during storage is evaluated based on the reduction in the amount of the polymerization inhibitor when the composition containing methacrylic acid is stored at 25°C for 21 days.

[0347] [Method for producing methacrylate]

[0348] The method for producing a methacrylic acid ester of the third embodiment includes a step of esterifying the methacrylic acid-containing composition of the third embodiment.

[0349] The alcohol to be reacted with the composition containing methacrylic acid is not particularly limited, and examples thereof include methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, and the like. Examples of the methacrylic acid esters obtained include methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, butyl methacrylate, and isobutyl methacrylate. The esterification reaction may be carried out in the presence of an acidic catalyst such as a sulfonic acid type cation exchange resin. The temperature in the esterification reaction is preferably 50 to 200°C.

[0350] The pressure during the esterification reaction, the position of the catalyst in the reactor, the ratio of the catalyst in the reactor, and the like are not particularly limited, and commonly used methods can be applied.

[0351] [Third Embodiment of the Method for Producing Methacrylic Acid Polymer]

[0352] The method for producing a methacrylic acid polymer of the third embodiment includes a step of polymerizing a polymerizable composition containing the methacrylic acid-containing composition of the third embodiment.

[0353] The polymerizable composition may contain a monomer copolymerizable with methacrylic acid and other additives as necessary.

[0354] Examples of the monomer copolymerizable with methacrylic acid include the following monomers.

[0355] Methacrylates such as methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, 2-ethylhexyl methacrylate, phenyl methacrylate, or benzyl methacrylate;

[0356] Acrylates such as methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, tert-butyl acrylate, or 2-ethylhexyl acrylate;

[0357] Unsaturated carboxylic acids such as acrylic acid, maleic acid, or itaconic acid;

[0358] Unsaturated carboxylic anhydrides such as maleic anhydride or itaconic anhydride;

[0359] Maleimides such as N-phenylmaleimide or N-cyclohexylmaleimide;

[0360] A vinyl monomer containing a hydroxyl group, such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, or 2-hydroxypropyl methacrylate;

[0361] Vinyl esters such as vinyl acetate or vinyl benzoate;

[0362] Vinyl chloride, vinylidene chloride and their derivatives;

[0363] Nitrogen-containing vinyl monomers such as methacrylamide or acrylonitrile;

[0364] Monomers containing epoxy groups such as glycidyl acrylate or glycidyl methacrylate;

[0365] Aromatic vinyl monomers such as styrene or α-methylstyrene;

[0366] Alkanediol di(meth)acrylates such as ethylene glycol di(meth)acrylate, 1,2-propylene glycol di(meth)acrylate, 1,3-butylene glycol di(meth)acrylate, or 1,6-hexanediol di(meth)acrylate;

[0367] Polyoxyalkylene glycol di(meth)acrylates such as diethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, triethylene glycol (meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, or neopentyl glycol di(meth)acrylate;

[0368] Vinyl monomers having two or more ethylenically unsaturated bonds in the molecule, such as divinylbenzene;

[0369] An unsaturated polyester prepolymer obtained from at least one polycarboxylic acid including an ethylenically unsaturated polycarboxylic acid and at least one diol;

[0370] A vinyl ester prepolymer obtained by modifying the epoxy group terminal with acrylic acid.

[0371] Among the above, the monomer copolymerizable with methacrylic acid is preferably at least one selected from methacrylic acid esters and acrylates. The monomer copolymerizable with methacrylic acid is more preferably methacrylic acid ester, and particularly preferably methyl methacrylate.

[0372] The monomer copolymerizable with methacrylic acid may be one or more. In addition, when component A3 is a monomer copolymerizable with methacrylic acid, component A3 may be used as a monomer copolymerizable with methacrylic acid, or a monomer copolymerizable with methacrylic acid different from component A3 may be used.

[0373] In the polymerizable composition, the content of the monomer copolymerizable with methacrylic acid is preferably 50.00 to 99.99 parts by mass relative to 100 parts by mass of the polymerizable composition. The lower limit of the content of the monomer copolymerizable with methacrylic acid is more preferably 60 parts by mass or more, further preferably 70 parts by mass or more, particularly preferably 80 parts by mass or more, and most preferably 90 parts by mass or more, relative to 100 parts by mass of the polymerizable composition. The upper limit of the content of the monomer copolymerizable with methacrylic acid is more preferably 99.9 parts by mass or less, further preferably 99 parts by mass or less, relative to 100 parts by mass of the polymerizable composition.

[0374] As other additives, polymerization initiators are preferred. In addition, the polymerizable composition may contain chain transfer agents, mold release agents, lubricants, plasticizers, antioxidants, antistatic agents, light stabilizers, ultraviolet absorbers, flame retardants, flame retardant aids, polymerization inhibitors, fillers, pigments, dyes, silane coupling agents, leveling agents, defoamers, fluorescent agents, etc. as needed. The other additives may be one or more.

[0375] Examples of the polymerization initiator include the following compounds.

[0376] Azo compounds such as 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), 2,2'-azobis(2-methylpropionitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2,4,4-trimethylpentane), 2,2'-azobis(2-methylpropane), 1,1-azobis(cyclohexanecarbonitrile), and 2,2'-azobisisobutyric acid dimethyl ester;

[0377] Benzoyl peroxide, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, 1,1-bis(tert-butylperoxy)cyclohexane, 1,1-bis(tert-butylperoxy)-3,5,5-trimethylcyclohexane, tert-butyl peroxy-2-ethylhexanoate, tert-butyl peroxyisobutyrate, tert-butyl peroxybenzoate, tert-hexyl peroxybenzoate, tert-butyl peroxyisopropyl monocarbonate, tert-butyl peroxy-3,5,5-trimethylhexanoate, tert-butyl peroxylaurate, tert-butyl peroxyacetate, tert-hexyl peroxyisopropyl monocarbonate, tert-ethyl peroxy Organic peroxides such as tert-hexyl hexanoate, tert-amyl peroxy-2-ethylhexanoate, 1,1,3,3-tetramethylbutyl peroxyethylhexanoate, 1,1,2-trimethylpropyl peroxy-2-ethylhexanoate, 1,1,3,3-tetramethylbutyl peroxyisopropyl monocarbonate, 1,1,2-trimethylpropyl peroxyisopropyl monocarbonate, 1,1,3,3-tetramethylbutyl peroxyisononanoate, 1,1,2-trimethylpropyl peroxy-isononanoate, di-tert-butyl peroxide, di-tert-hexyl peroxide, lauroyl peroxide, and dilauroyl peroxide;

[0378] Persulfate compounds such as potassium persulfate;

[0379] Redox polymerization initiator.

[0380] Among the above, the polymerization initiator is preferably at least one selected from azo compounds and organic peroxides from the viewpoint of storage stability and reactivity of methacrylic acid with a copolymerizable monomer.

[0381] The amount of the polymerization initiator used is preferably 0.0001 to 1 part by mass based on 100 parts by mass of the total of methacrylic acid and the monomer copolymerizable with methacrylic acid.

[0382] Examples of the polymerization method for the polymerizable composition include bulk polymerization, solution polymerization, emulsion polymerization, and suspension polymerization.

[0383] The polymerization temperature is preferably 125 to 210° C. This allows for an appropriate polymerization rate. More preferably, the lower limit of the polymerization temperature is 130° C. or higher and the upper limit is 180° C. or lower. The polymerization time is not particularly limited and may be, for example, 0.5 to 24 hours.

[0384] [Methacrylic acid-containing composition of the fourth aspect]

[0385] The methacrylic acid-containing composition of the fourth embodiment contains methacrylic acid, a compound represented by the following formula (41) (component A4), and a polymerization inhibitor (component B). The concentration of methacrylic acid is 98.00 to 99.99% by mass.

[0386] R d -C≡N…(41)

[0387] In formula (41), R d It represents an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms, and these groups may further have a substituent.

[0388] Furthermore, the composition containing methacrylic acid may contain other compounds (component C) and water as long as the concentration of methacrylic acid satisfies 98.00 to 99.99% by mass. Each item will be described in detail below.

[0389] (Methacrylic acid)

[0390] The methacrylic acid-containing composition of the fourth embodiment contains methacrylic acid. Methacrylic acid can be produced, for example, as a byproduct of the acetone cyanohydrin (ACH) method or as an intermediate of the C4 direct oxidation method. The methacrylic acid contained in the methacrylic acid-containing composition is preferably produced by the C4 direct oxidation method, and more preferably produced by the C4 direct oxidation method using biomass-derived isobutyl alcohol as a starting material.

[0391] (ingredient A4)

[0392] The methacrylic acid-containing composition of the fourth embodiment contains the compound represented by the above formula (41) (component A4). When the methacrylic acid-containing composition contains component A4, decomposition of the polymerization inhibitor can be suppressed. The reason for this is presumed to be as follows.

[0393] It is known that methacrylic acid will polymerize due to free radicals generated during storage, and a polymerization inhibitor (component B) is added to prevent polymerization. Component B has an anti-polymerization function by capturing free radicals generated during storage of methacrylic acid, but since the polymerization inhibitor decomposes into other compounds when capturing free radicals, the concentration of component B in the composition containing methacrylic acid gradually decreases during storage, resulting in a gradual decrease in the anti-polymerization function. In addition, the unwanted decomposition products generated by component B capturing free radicals gradually increase. As an example of free radicals generated during storage of methacrylic acid, hydroxyl radicals generated by oxygen molecules absorbing ultraviolet light from sunlight can be cited. Since component A4 has weak alkalinity, it preferably generates hydroxyl ions (OH － ), inhibiting the generation of hydroxyl radicals. Therefore, the radicals that component B needs to capture are reduced, thereby suppressing the reduction in the concentration of component B.

[0394] The molecular weight of component A4 is preferably 1000 or less. By having a molecular weight of 1000 or less, the number of cyano groups per unit mass in component A4 can be increased, thereby being able to obtain the effect of the present invention with less mass. The molecular weight of component A4 is more preferably 800 or less, further preferably 600 or less, and particularly preferably 400 or less.

[0395] In the above formula (41), R d It represents an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms, and these groups may further have a substituent.

[0396] R d When the above conditions are met, the weak alkalinity of component A4 and its reactivity with acidic substances and free radicals can be maintained, so the effect of the present invention can be obtained. In addition, since it is a highly stable group, component A4 can be prevented from changing into other compounds during storage. d It is preferably an alkyl group having 1 to 3 carbon atoms, an alkenyl group having 2 to 3 carbon atoms, or an aryl group having 6 to 8 carbon atoms. d More preferred are methyl, ethyl, vinyl, isopropenyl, phenyl, methylthiophenyl, acetoxyphenyl and cyanophenyl; further preferred are methyl, ethyl, vinyl, isopropenyl, methylthiophenyl, acetoxyphenyl and cyanophenyl; particularly preferred are methyl, ethyl, vinyl, isopropenyl, acetoxyphenyl and cyanophenyl.

[0397] The alkyl group is a chain (straight or branched) alkyl group or a cyclic alkyl group. Examples of chain alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, etc. Among them, methyl, ethyl, n-propyl, isopropyl, and methyl or ethyl are preferred. In addition, examples of cyclic alkyl groups include cyclopropyl, cyclobutyl, cyclopentyl, etc.

[0398] The alkenyl group is a chain (straight or branched) alkenyl group or a cyclic alkenyl group. Examples of chain alkenyl groups include vinyl, 1-propenyl, isopropenyl, 2-butenyl, 1,3-butadienyl, and 2-pentenyl. Among them, vinyl, 1-propenyl, and isopropenyl are preferred, and vinyl or isopropenyl is more preferred. In addition, examples of cyclic alkenyl groups include cyclopropenyl, cyclobutene, and cyclopentenyl.

[0399] The aryl group includes a heteroaryl group containing oxygen, nitrogen, sulfur, etc. Examples of the aryl group include phenyl, mesityl, naphthyl, 2-methylphenyl, 3-methylphenyl, 4-methylphenyl, 2,3-dimethylphenyl, 2,4-dimethylphenyl, 2,5-dimethylphenyl, 2,6-dimethylphenyl, 2-ethylphenyl, isothiophene, 1-butylphenyl, 1-butylphenyl, 2-isothiophene ... Azolyl, isothiazolyl, imidazolyl, oxazolyl, thiazolyl, thiadiazolyl, thienyl, triazolyl, tetrazolyl, pyridyl, pyrazinyl, pyrimidinyl, pyridazinyl, pyrazolyl, pyrrolyl, furanyl, furazanyl, isoquinolyl, isoindolyl, indolyl, quinolyl, pyridothiazolyl, benzimidazolyl, benzo oxazolyl, benzothiazolyl, benzotriazolyl, benzofuranyl, imidazopyridinyl, triazolopyridinyl, purinyl.

[0400] R d In the case of an alkyl group, alkenyl group or aryl group having a substituent, examples of the substituent include alkyl groups, alkenyl groups, aryl groups, hydroxyl groups, alkoxyl groups, amino groups, monovalent groups containing carbonyl groups, alkylthio groups and arylthio groups. Among them, hydroxyl groups, alkoxyl groups, amino groups, monovalent groups containing carbonyl groups and alkylthio groups are preferred, and hydroxyl groups, methoxyl groups, amino groups, acetyl groups and methylthio groups are more preferred. The molecular weight of the substituent is preferably 200 or less, more preferably 100 or less, and further preferably 50 or less. R d The number of carbon atoms in the alkyl, alkenyl or aryl group includes the carbon atoms of the substituents. d It is 4-(methylthio)phenyl, which is regarded as an aryl group having 7 carbon atoms.

[0401] As a substituent, the alkyl group only needs R d The alkyl group is the same as the above-mentioned alkyl group when it is an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, or an aryl group having 1 to 12 carbon atoms. The alkyl group as a substituent has 1 to 11 carbon atoms, preferably 1 to 6 carbon atoms, and more preferably 1 to 3 carbon atoms.

[0402] As a substituent, alkenyl groups only need R dThe same as the above-mentioned alkenyl group when it is an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, or an aryl group having 1 to 12 carbon atoms. The alkenyl group as a substituent has 2 to 11 carbon atoms, preferably 2 to 6 carbon atoms, and more preferably 2 to 3 carbon atoms.

[0403] As an aryl substituent, R d The aryl group is the same as the above-mentioned aryl group when it is an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, or an aryl group having 1 to 12 carbon atoms. The aryl group as a substituent has 1 to 11 carbon atoms, preferably 3 to 9 carbon atoms, and more preferably 5 to 7 carbon atoms.

[0404] The alkoxy group as a substituent is an alkoxy group having 1 to 11 carbon atoms, preferably an alkoxy group having 1 to 6 carbon atoms, and more preferably an alkoxy group having 1 to 3 carbon atoms. d It is an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, or an aryl group having 1 to 12 carbon atoms. Examples of the alkoxy group include methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, sec-butoxy, tert-butoxy, n-pentoxy, isopentyloxy, and phenoxy.

[0405] The amino group as a substituent includes an amino group without a substituent on the nitrogen atom (-NH 2 ) (carbon number 0), and an amino group in which a part or all of the hydrogen atoms bonded to the nitrogen atom are substituted with carbon atoms. The number of carbon atoms of the amino group in which a part or all of the hydrogen atoms bonded to the nitrogen atom are substituted with carbon atoms is 1 to 11, preferably 1 to 6, and more preferably 1 to 3. d is an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, or an aryl group having 1 to 12 carbon atoms. Examples of the amino group include an unsubstituted amino group (—NH 2 ), methylamino, ethylamino, propylamino, butylamino, dimethylamino, diethylamino, aniline, toluidine, anisidine, N-methyl-N-phenylamino, etc.

[0406] Examples of the monovalent group containing a carbonyl group as a substituent include a formyl group, an acyl group, a carboxyl group, an amide group, an alkoxycarbonyl group, a thiocarboxyl group, and a thioester group.

[0407] The acyl group is a substituent formed by connecting a carbonyl group to an alkyl group, an alkenyl group, or an aryl group. The total number of carbon atoms (1) derived from the carbonyl group and the number of carbon atoms derived from the alkyl group, the alkenyl group, or the aryl group is 2 to 11, preferably 2 to 7, and more preferably 2 to 4. d It is an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, or an aryl group having 1 to 12 carbon atoms. Examples of the acyl group include acetyl, propionyl, butyryl, vinylcarbonyl, and benzoyl.

[0408] The amide group includes an amide group with no substituent on the nitrogen atom (-CONH 2 ), and an amide group in which a part or all of the hydrogen atoms bonded to the nitrogen atom are substituted with carbon atoms. The number of carbon atoms in the amide group is 1 to 11, preferably 1 to 7, and more preferably 1 to 4, based on the total number of carbon atoms from the carbonyl group (1) and the number of carbon atoms substituted on the nitrogen atom. d It is an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, or an aryl group having 1 to 12 carbon atoms. Examples of the amide group include an unsubstituted amide group, an N-methylamide group, an N-ethylamide group, an N-phenylamide group, an N,N-dimethylamide group, and an N-methyl-N-phenylamide group.

[0409] The alkoxycarbonyl group is a substituent formed by connecting a carbonyl group to an alkoxy group, and is also called an ester group. The total number of carbon atoms derived from the carbonyl group (1) and the number of carbon atoms derived from the alkoxy group is 2 to 11, preferably 2 to 7, and more preferably 2 to 4. d It is an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, or an aryl group having 1 to 12 carbon atoms. Examples of the alkoxycarbonyl group include a methoxycarbonyl group, an ethoxycarbonyl group, a butoxycarbonyl group, and a phenoxycarbonyl group.

[0410] The thioester group is a substituent formed by connecting a carbonyl group to an alkylthio group or an arylthio group. The total number of carbon atoms (1) derived from the carbonyl group and the number of carbon atoms derived from the alkylthio group or the arylthio group is 2 to 11, preferably 2 to 7, and more preferably 2 to 4. d It is an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, or an aryl group having 1 to 12 carbon atoms. Examples of the thioester group include methylthiocarbonyl, ethylthiocarbonyl, butylthiocarbonyl, and phenylthiocarbonyl.

[0411] In addition, the monovalent group containing a carbonyl group may be a substituent in which one or more hydrogen atoms of an alkyl group are replaced by a carbonyl group. Examples of such a substituent include 2-acetoxyethyl, 2-acetylethyl, and 2-(acetoacetoxy)ethyl.

[0412] The alkylthio group as a substituent is an alkylthio group having 1 to 11 carbon atoms, preferably an alkylthio group having 1 to 6 carbon atoms, and more preferably an alkylthio group having 1 to 3 carbon atoms. d It is an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, or an aryl group having 1 to 12 carbon atoms. Examples of the alkylthio group include a methylthio group, an ethylthio group, a propylthio group, and an isopropylthio group.

[0413] The arylthio group as a substituent is an arylthio group having 1 to 11 carbon atoms, preferably an arylthio group having 3 to 10 carbon atoms, and more preferably an arylthio group having 6 to 10 carbon atoms. d It is an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, or an aryl group having 1 to 12 carbon atoms. Examples of the arylthio group include a phenylthio group and a tolylthio group.

[0414] Among the compounds satisfying the above conditions, from the viewpoint of quality stability of the methacrylic acid-containing composition during storage, component A4 is preferably methacrylonitrile, acetonitrile, propionitrile, acrylonitrile, benzonitrile, 3-hydroxypropionitrile, 3-methoxypropionitrile, 4-aminobenzonitrile, 4'-cyanoacetophenone, 4-(methylthio)benzonitrile, 2-hydroxypropionitrile, 2-aminopropionitrile, or 4-cyanophenol; more preferably methacrylonitrile, acetonitrile, propionitrile, acrylonitrile, benzonitrile, 3-hydroxypropionitrile, 3-methoxypropionitrile, 4-aminobenzonitrile, 4'-cyanoacetophenone, or 4-(methylthio)benzonitrile; further preferably methacrylonitrile, acetonitrile, propionitrile, acrylonitrile, 4-cyanoacetophenone, and 4-(methylthio)benzonitrile; and particularly preferably methacrylonitrile, acetonitrile, propionitrile, acrylonitrile, and 4-cyanoacetophenone.

[0415] Component A4 may be used in one kind or in two or more kinds.

[0416] (ingredient B)

[0417] The composition containing methacrylic acid in the fourth embodiment contains a polymerization inhibitor (component B). In the present specification, a polymerization inhibitor refers to a compound having the function of inhibiting the polymerization reaction of methacrylic acid. As the polymerization inhibitor, for example, phenolic compounds, quinone compounds, nitrobenzene compounds, N-oxyl radical compounds, amine compounds, phosphorus-containing compounds, sulfur-containing compounds, iron-containing compounds, copper-containing compounds and manganese-containing compounds can be cited. By containing component B, the polymerization reaction of methacrylic acid based on the free radical polymerization mechanism during the storage of methacrylic acid can be inhibited. In addition, component B can capture the above-mentioned hydroxyl radicals generated during the storage of methacrylic acid. That is, when the composition containing methacrylic acid contains component B in addition to component A4, the amount of hydroxyl radicals can be reduced by the following two different mechanisms, namely, the generation of hydroxyl radicals can be inhibited by component A4, and the generated hydroxyl radicals can be removed by component B. Therefore, it is believed that the reduction of component B can be effectively inhibited.

[0418] Examples of the polymerization inhibitor as a phenolic compound include alkylphenols, hydroxyphenols, aminophenols, nitrophenols, nitrosophenols, alkoxyphenols, and tocopherol.

[0419] Examples of the alkylphenol include o-cresol, m-cresol, p-cresol, 2-tert-butyl-4-methylphenol, 2,4-dimethyl-6-tert-butylphenol, 2,6-di-tert-butyl-4-methylphenol, 2-tert-butylphenol, 4-tert-butylphenol, 2,4-di-tert-butylphenol, 2-methyl-4-tert-butylphenol, 4-tert-butyl-2,6-dimethylphenol, 2,2′-methylenebis(4-ethyl-6-tert-butylphenol), 4,4′-thiobis(3-methyl-6-tert-butylphenol), and 3,5-di-tert-butyl-4-hydroxytoluene.

[0420] Examples of the hydroxyphenol include hydroquinone, 2-methylhydroquinone, 2-tert-butylhydroquinone, 2,5-di-tert-butylhydroquinone, 2,6-di-tert-butylhydroquinone, 2,5-di-tert-amylhydroquinone, 2-tert-butylmethoxyhydroquinone, 2,3,5-trimethylhydroquinone, 2,5-dichlorohydroquinone, 1,2-dihydroxybenzene, 2-acetylhydroquinone, 4-methylcatechol, 4-tert-butylcatechol, 2-methylresorcinol, 4-methylresorcinol, and 2,3-dihydroxyacetophenone.

[0421] Examples of the aminophenol include o-aminophenol, m-aminophenol, p-aminophenol, 2-(N,N-dimethylamino)phenol, and 4-(ethylamino)phenol.

[0422] Examples of the nitrophenol include o-nitrophenol, m-nitrophenol, p-nitrophenol, and 2,4-dinitrophenol.

[0423] Examples of the nitrosophenol include o-nitrosophenol, m-nitrosophenol, p-nitrosophenol, and α-nitroso-β-naphthol.

[0424] Examples of the alkoxyphenol include 2-methoxyphenol, 2-ethoxyphenol, 2-isopropoxyphenol, 2-tert-butoxyphenol, 4-methoxyphenol, 4-ethoxyphenol, 4-propoxyphenol, 4-butoxyphenol, 4-tert-butoxyphenol, 4-heptyloxyphenol, hydroquinone monobenzyl ether, tert-butyl-4-methoxyphenol, di-tert-butyl-4-methoxyphenol, pyrogallol-1,2-dimethyl ether, and hydroquinone monobenzoate.

[0425] Examples of the tocopherol include α-tocopherol and 2,3-dihydro-2,2-dimethyl-7-hydroxybenzofuran.

[0426] Examples of the polymerization inhibitor as a quinone compound include p-benzoquinone, chloro-p-benzoquinone, 2,5-dichloro-p-benzoquinone, 2,6-dichloro-p-benzoquinone, tetrachloro-p-benzoquinone, tetrabromo-p-benzoquinone, 2,3-dimethyl-p-benzoquinone, 2,5-dimethyl-p-benzoquinone, methoxy-p-benzoquinone, and methyl-p-benzoquinone.

[0427] Examples of the polymerization inhibitor as a nitrobenzene compound include nitrobenzene, o-dinitrobenzene, m-dinitrobenzene, p-dinitrobenzene, 2,4-dinitrobenzene, dinitrodurene, and 2,2-diphenyl-1-picrylhydrazyl.

[0428] Examples of the polymerization inhibitor as an N-oxyl radical compound include 4-hydroxy-2,2,6,6-tetramethyl-piperidin-N-oxyl radical, 4-oxo-2,2,6,6-tetramethyl-piperidin-N-oxyl radical, 4-acetoxy-2,2,6,6-tetramethyl-piperidin-N-oxyl radical, 2,2,6,6-tetramethyl-piperidin-N-oxyl radical, piperidine-1-oxyl radical, 4-(dimethylamino)-2,2,6,6-tetramethyl-piperidin-N-oxyl radical, 4-amino-2,2,6,6-tetramethyl-piperidin-N-oxyl radical, 4-vinyloxy-2,2,6,6-tetramethyl-piperidin-N-oxyl radical, 4-benzoyloxy-2,2,6,6-tetramethyl-piperidin-N-oxyl radical, -N-oxyl free radical, 2,2,5,5-tetramethyl-piperidinyl-N-oxyl free radical, 3-amino-2,2,5,5-tetramethyl-piperidinyl-N-oxyl free radical, 4,4',4"-tris(2,2,6,6-tetramethyl-piperidinyl-N-oxyl free radical)phosphite, 3-oxo-2,2,5,5-tetramethylpyrrolidine-N-oxyl free radical, pyrrolidine-1-oxyl free radical, 2,2,5,5-tetramethyl-1-oxa-3-azacyclopentyl-3-oxyl free radical, 2,2,5,5-tetramethyl-3-pyrrolinyl-1-oxyl-3-carboxylic acid, 2,2,3,3,5,5,6,6-octamethyl-1,4-diazacyclohexyl-1,4-dioxyl free radical, di-tert-butylnitroxide, di-tert-amylnitroxide, etc.

[0429] Examples of the polymerization inhibitor as an amine compound include N,N-diphenylamine, alkylated diphenylamine, 4,4'-dicumyldiphenylamine, 4,4'-dioctyldiphenylamine, 4-aminodiphenylamine, p-nitrosodiphenylamine, N-nitrosodinaphthylamine, N-nitrosodiphenylamine, N-nitrosophenylnaphthylamine, N-nitrosophenylhydroxylamine, N,N'-dialkyl-p-phenylenediamine (the alkyl groups may be the same or different, each independently having 1 to 4 carbon atoms, and may be linear or branched), N,N'-diphenyl-p-phenylenediamine, N-phenyl-N'-isopropyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-1,4-phenylenediamine, N,N'-di-2-naphthylamine, 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline, 2,2,4-trimethyl-1,2-dihydroquinoline polymer, butyral-α-naphthylamine, N-phenyl-β-naphthylamine, 4-hydroxy-2,2,6,6-tetramethylpiperidine, 4-benzoyloxy-2,2,6,6-tetramethylpiperidine, 1,4-dihydroxy-2,2,6,6-tetramethylpiperidine, 1-hydroxy-4-benzoyloxy-2,2,6,6-tetramethylpiperidine, etc.

[0430] Examples of the polymerization inhibitor as a phosphorus-containing compound include triphenylphosphine, triphenyl phosphite, triethyl phosphite, tris(isodecyl) phosphite, tris(tridecyl) phosphite, phenyl diisooctyl phosphite, phenyl diisodecyl phosphite, phenyl di(tridecyl) phosphite, diphenyl isooctyl phosphite, diphenyl isodecyl phosphite, diphenyl tridecyl phosphite, [1,1-diphenyl-4,4'-diyl-bis[tetrakis-2,4-bis(1,1-dimethylethyl)phenyl]]phosphonate, tris(nonylphenyl) phosphite, 4,4'-isopropylidene diphenol alkyl phosphite, tris(2,4-di-tert-butylphenyl) phosphite, and terphenyl phosphite. Ester, distearyl pentaerythritol diphosphite, di(2,4-di-tert-butylphenyl) pentaerythritol diphosphite, di(nonylphenyl) pentaerythritol diphosphite, phenyl bisphenol A pentaerythritol diphosphite, tetra(tridecyl)-4,4'-butylidene bis(3-methyl-6-tert-butylphenol) diphosphite, hexa(tridecyl)-1,1,3-tri(2-methyl-4-hydroxy-5-tert-butylphenyl) butane triphosphite, 3,5-di-tert-butyl-4-hydroxybenzyl phosphate diethyl ester, bis(4-tert-butylphenyl) phosphate sodium salt, 2,2'-methylene-bis(4,6-di-tert-butylphenyl) phosphate sodium salt, 1,3-bis(diphenoxyphosphoryloxy)benzene, etc.

[0431] Examples of the polymerization inhibitor as a sulfur-containing compound include diphenyl sulfide, phenothiazine, 3-oxophenothiazine, 5-oxophenothiazine, phenothiazine dimer, 1,4-dimercaptobenzene, 1,2-dimercaptobenzene, 2-mercaptophenol, 4-mercaptophenol, 2-(methylthio)phenol, and 3,7-bis(dimethylamino)phenothiazine. Chloride, sulfur (elemental), etc.

[0432] Examples of the polymerization inhibitor as an iron-containing compound include iron (III) chloride and the like.

[0433] Examples of the polymerization inhibitor as a copper compound include copper dimethyldithiocarbamate, copper diethyldithiocarbamate, copper dibutyldithiocarbamate, copper salicylate, copper acetate, copper thiocyanate, copper nitrate, copper chloride, copper carbonate, copper hydroxide, copper acrylate, copper methacrylate, and the like.

[0434] Examples of the polymerization inhibitor as a manganese-containing compound include manganese dialkyldithiocarbamate (the alkyl group is any of methyl, ethyl, propyl and butyl, and may be the same or different), manganese diphenyldithiocarbamate, manganese formate, manganese acetate, manganese octoate, manganese naphthenate, manganese permanganate, and manganese salt of ethylenediaminetetraacetic acid.

[0435] Among the above, from the viewpoint of quality stability of the composition containing methacrylic acid during storage, as component B, at least one polymerization inhibitor selected from phenolic compounds, N-oxyl radical compounds, amine compounds, phosphorus-containing compounds and sulfur-containing compounds is preferred, for example, preferably at least one polymerization inhibitor selected from hydroquinone, 4-methoxyphenol, 2,4-dimethyl-6-tert-butylphenol, 2,6-di-tert-butyl-4-methylphenol, 4-hydroxy-2,2,6,6-tetramethylpiperidinyl-N-oxyl radical, N,N-diphenylamine, N-nitrosodiphenylamine, triphenyl phosphite and phenothiazine. Component B is more preferably a phenolic compound, for example, more preferably at least one polymerization inhibitor selected from hydroquinone, 4-methoxyphenol, 2,4-dimethyl-6-tert-butylphenol and 2,6-di-tert-butyl-4-methylphenol. Component B is particularly preferably at least one polymerization inhibitor selected from hydroquinone and 4-methoxyphenol.

[0436] Component B may be one kind or two or more kinds.

[0437] When the composition containing methacrylic acid contains a compound corresponding to both component A4 and component B, the compound is regarded as component B. That is, the composition containing methacrylic acid needs to contain component A4 different from the compound. When two or more compounds corresponding to both component A4 and component B are contained, the compound with the highest molar concentration in the composition containing methacrylic acid is regarded as component B, and the other compounds are regarded as component A4.

[0438] (Concentration of Component A4 and Component B)

[0439] The concentration of component A4 is M A4 (μmol / L), the concentration of component B is set to M B (μmol / L), from the perspective of the efficiency of inhibiting the production of methacrylic acid dimers and pyruvic acid, M B / M A4 It is preferably 0.005-100, more preferably 0.05-10.

[0440] M A4 It is preferably 1 to 40000 μmol / L. A4 When the concentration of M is 1 μmol / L or more, the effect of inhibiting the decomposition of the polymerization inhibitor can be fully obtained. A4 When the concentration is 40000 μmol / L or less, the amount of impurities in producing a methacrylic acid polymer by polymerization of the methacrylic acid-containing composition of the fourth embodiment can be reduced, and adverse effects on the physical properties of the polymer can be prevented. A4 The lower limit of M is more preferably 10 μmol / L or more, further preferably 30 μmol / L or more, further preferably 50 μmol / L or more, further preferably 60 μmol / L or more, particularly preferably 70 μmol / L or more, and even more preferably 80 μmol / L or more. A4 The upper limit is more preferably 3000 μmol / L or less, further preferably 25000 μmol / L or less, and particularly preferably 20000 μmol / L or less.

[0441] M B It is preferably 1 to 50000 μmol / L. B When the concentration of M is 1 μmol / L or more, the effect of inhibiting the production of methacrylic acid dimers and pyruvic acid can be fully obtained. B When the concentration is 50000 μmol / L or less, the amount of impurities in producing a methacrylic acid polymer by polymerization of the methacrylic acid-containing composition of the fourth embodiment can be reduced, and the physical properties of the polymer can be prevented from being adversely affected. BThe lower limit of M is more preferably 10 μmol / L or more, further preferably 100 μmol / L or more, particularly preferably 1500 μmol / L or more, and even more preferably 2000 μmol / L or more. B The upper limit is more preferably 45000 μmol / L or less, further preferably 40000 μmol / L or less, particularly preferably 35000 μmol / L or less, even more preferably 30000 μmol / L or less, and most preferably 25000 μmol / L or less.

[0442] (Methacrylic acid concentration)

[0443] The methacrylic acid concentration of the methacrylic acid-containing composition of the fourth embodiment is 98.00 to 99.99% by mass. When the methacrylic acid concentration is 98.00% by mass or more, the amount of impurities when the methacrylic acid polymer is produced by polymerization of the methacrylic acid-containing composition of the fourth embodiment can be reduced, and the physical properties of the polymer can be prevented from being adversely affected. In addition, by setting the methacrylic acid concentration to 99.99% by mass or less, the purification cost can be reduced. The lower limit of the methacrylic acid concentration is more preferably 98.50% or more, further preferably 99.00% or more, particularly preferably 99.50% or more, and most preferably 99.80% or more by mass.

[0444] (Ingredient C)

[0445] The composition containing methacrylic acid of the fourth embodiment may further contain component C as another compound as long as the concentration of methacrylic acid is 98.00 to 99.99% by mass. Examples of component C include impurities generated in the production process of methacrylic acid. For example, methacrylic acid may contain diacetyl as an impurity. From the viewpoint of reducing the coloration of the composition containing methacrylic acid, the concentration of diacetyl is preferably 55 μmol / L, more preferably 20 μmol / L or less, further preferably 10 μmol / L or less, and particularly preferably 1 μmol / L or less.

[0446] (Analysis of Compositions Containing Methacrylic Acid)

[0447] The fact that the composition containing methacrylic acid contains component A4, component B, component C, and water can be confirmed by, for example, GC-MS measurement. In the GC-MS spectrum of the composition containing methacrylic acid, if there is a peak at the same retention time as the standard of component A4, and the m / z value detected in the mass spectrum of the peak is consistent with the accurate mass of component A4, it can be determined that the composition containing methacrylic acid contains component A4. In the case where a standard of component A4 is not available, when the pattern of the mass spectrum of the peak appearing in the GC-MS spectrum of the composition containing methacrylic acid is consistent with the pattern of the mass spectrum of component A4 included in the mass spectrum database, it can be determined that the peak is the component A4 peak. That is, it can be determined that the composition containing methacrylic acid contains component A4. As mass spectrum databases, NIST20, NIST17, NIST14, NIST14s, etc. can be cited. In addition, when the volatility is low and it cannot be detected by GC-MS measurement, LC-MS can be used for detection. Component B, component C, and water can also be confirmed by the same method as component A1.

[0448] In addition, the concentration of methacrylic acid can be calculated by, for example, performing GC-FID measurement on a composition containing methacrylic acid, quantifying it using the area percentage method, and correcting it using the amount of water quantified by a Karl Fischer titrator. The concentration of component A4 can be quantified by, for example, performing GC measurement on a composition containing methacrylic acid and using an internal standard method. If a standard product of component A4 is not available and quantification cannot be performed using the internal standard method, an organic compound with a known concentration can be subjected to GC-FID measurement under the same conditions as the composition containing methacrylic acid, and the concentration of component A4 can be calculated using the following formula.

[0449]

[0450] Here, N is the number of carbon atoms in one molecule of an organic compound with a known concentration. A4 is the number of carbon atoms in one molecule of component A4, S A4 is the peak area of ​​component A4, S is the peak area of ​​the organic compound of known concentration, and M is the concentration (μmol / L) of the organic compound of known concentration.

[0451] When volatility is low and quantification by GC is not possible, quantification can be performed by chromatography such as LC.

[0452] The concentrations of component B and component C can also be calculated by the same method as that of component A4 described above.

[0453] In addition, the presence of water in the composition containing methacrylic acid and the concentration of water can be confirmed by Karl Fischer method.

[0454] [Method for producing a composition containing methacrylic acid]

[0455] As a fourth method for producing a composition containing methacrylic acid, there can be mentioned a method of adding component A4 and component B to methacrylic acid. Methacrylic acid can use a commercial product, or methacrylic acid produced by a known method such as the acetone cyanohydrin (ACH) method and the C4 direct oxidation method. Component A4 and component B can use a commercial product, or a compound synthesized by a known method. In the case of using a substance produced by a known method such as the acetone cyanohydrin (ACH) method and the C4 direct oxidation method for methacrylic acid, component A4 or component B can be added in the middle of the raw material or the production process to produce a composition containing methacrylic acid. In addition, in the case where component A4 or component B is generated as a by-product in the methacrylic acid production process, a composition containing methacrylic acid can be produced by leaving a portion of the generated component A4 or component B.

[0456] [Evaluation method of storage stability and thermal stability]

[0457] The fourth embodiment has high quality stability of the methacrylic acid-containing composition during storage. As an evaluation method for the quality stability of the methacrylic acid-containing composition during storage, for example, a method of actually storing the methacrylic acid-containing composition for a long time and confirming the reduction in the amount of the polymerization inhibitor can be cited. In addition, from the perspective of simplicity of operation, a method of heating the methacrylic acid-containing composition for a short time and confirming the reduction in the amount of the polymerization inhibitor can be used. When heating for a short time, the heating temperature is preferably 50 to 100°C, and the heating time is preferably 1 to 24 hours. In the present invention, the reduction in the amount of the polymerization inhibitor when the methacrylic acid-containing composition is stored at 25°C for 21 days is confirmed, and the quality stability of the methacrylic acid-containing composition during storage is evaluated based on the reduction in the amount of the polymerization inhibitor.

[0458] [Method for producing methacrylate]

[0459] The method for producing a methacrylic acid ester of the fourth aspect includes a step of esterifying the methacrylic acid-containing composition of the fourth aspect.

[0460] The alcohol to be reacted with the composition containing methacrylic acid is not particularly limited, and examples thereof include methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, and the like. Examples of the methacrylic acid esters obtained include methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, butyl methacrylate, and isobutyl methacrylate. The esterification reaction may be carried out in the presence of an acidic catalyst such as a sulfonic acid type cation exchange resin. The temperature in the esterification reaction is preferably 50 to 200°C.

[0461] The pressure during the esterification reaction, the position of the catalyst in the reactor, the ratio of the catalyst in the reactor, and the like are not particularly limited, and commonly used methods can be applied.

[0462] [Method for producing methacrylic acid polymer according to the fourth aspect]

[0463] The method for producing a methacrylic acid polymer of the fourth embodiment includes a step of polymerizing a polymerizable composition containing the methacrylic acid-containing composition of the fourth embodiment.

[0464] The polymerizable composition may contain a monomer copolymerizable with methacrylic acid and other additives as necessary.

[0465] Examples of the monomer copolymerizable with methacrylic acid include the following monomers.

[0466] Methacrylates such as methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, 2-ethylhexyl methacrylate, phenyl methacrylate, or benzyl methacrylate;

[0467] Acrylates such as methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, tert-butyl acrylate, or 2-ethylhexyl acrylate;

[0468] Unsaturated carboxylic acids such as acrylic acid, maleic acid, or itaconic acid;

[0469] Unsaturated carboxylic anhydrides such as maleic anhydride or itaconic anhydride;

[0470] Maleimides such as N-phenylmaleimide or N-cyclohexylmaleimide;

[0471] A vinyl monomer containing a hydroxyl group, such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, or 2-hydroxypropyl methacrylate;

[0472] Vinyl esters such as vinyl acetate or vinyl benzoate;

[0473] Vinyl chloride, vinylidene chloride and their derivatives;

[0474] Nitrogen-containing vinyl monomers such as methacrylamide or acrylonitrile;

[0475] Monomers containing epoxy groups such as glycidyl acrylate or glycidyl methacrylate;

[0476] Aromatic vinyl monomers such as styrene or α-methylstyrene;

[0477] Alkanediol di(meth)acrylates such as ethylene glycol di(meth)acrylate, 1,2-propylene glycol di(meth)acrylate, 1,3-butylene glycol di(meth)acrylate, or 1,6-hexanediol di(meth)acrylate;

[0478] Polyoxyalkylene glycol di(meth)acrylates such as diethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, triethylene glycol (meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, or neopentyl glycol di(meth)acrylate;

[0479] Vinyl monomers having two or more ethylenically unsaturated bonds in the molecule, such as divinylbenzene;

[0480] An unsaturated polyester prepolymer obtained from at least one polycarboxylic acid including an ethylenically unsaturated polycarboxylic acid and at least one diol;

[0481] A vinyl ester prepolymer obtained by modifying the epoxy group terminal with acrylic acid.

[0482] Among the above, the monomer copolymerizable with methacrylic acid is preferably at least one selected from methacrylic acid esters and acrylates. The monomer copolymerizable with methacrylic acid is more preferably methacrylic acid ester, and particularly preferably methyl methacrylate.

[0483] The monomer copolymerizable with methacrylic acid may be one or more. In addition, when component A4 is a monomer copolymerizable with methacrylic acid, component A4 may be used as a monomer copolymerizable with methacrylic acid, or a monomer copolymerizable with methacrylic acid different from component A4 may be used.

[0484] In the polymerizable composition, the content of the monomer copolymerizable with methacrylic acid is preferably 50.00 to 99.99 parts by mass relative to 100 parts by mass of the polymerizable composition. The lower limit of the content of the monomer copolymerizable with methacrylic acid is more preferably 60 parts by mass or more, further preferably 70 parts by mass or more, particularly preferably 80 parts by mass or more, and most preferably 90 parts by mass or more, relative to 100 parts by mass of the polymerizable composition. The upper limit of the content of the monomer copolymerizable with methacrylic acid is more preferably 99.9 parts by mass or less, further preferably 99 parts by mass or less, relative to 100 parts by mass of the polymerizable composition.

[0485] As other additives, polymerization initiators are preferred. In addition, the polymerizable composition may contain chain transfer agents, mold release agents, lubricants, plasticizers, antioxidants, antistatic agents, light stabilizers, ultraviolet absorbers, flame retardants, flame retardant aids, polymerization inhibitors, fillers, pigments, dyes, silane coupling agents, leveling agents, defoamers, fluorescent agents, etc. as needed. The other additives may be one or more.

[0486] Examples of the polymerization initiator include the following compounds.

[0487] Azo compounds such as 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), 2,2'-azobis(2-methylpropionitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2,4,4-trimethylpentane), 2,2'-azobis(2-methylpropane), 1,1-azobis(cyclohexanecarbonitrile), and 2,2'-azobisisobutyric acid dimethyl ester;

[0488] Benzoyl peroxide, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, 1,1-bis(tert-butylperoxy)cyclohexane, 1,1-bis(tert-butylperoxy)-3,5,5-trimethylcyclohexane, tert-butyl peroxy-2-ethylhexanoate, tert-butyl peroxyisobutyrate, tert-butyl peroxybenzoate, tert-hexyl peroxybenzoate, tert-butyl peroxyisopropyl monocarbonate, tert-butyl peroxy-3,5,5-trimethylhexanoate, tert-butyl peroxylaurate, tert-butyl peroxyacetate, tert-hexyl peroxyisopropyl monocarbonate, tert-ethyl peroxy Organic peroxides such as tert-hexyl hexanoate, tert-amyl peroxy-2-ethylhexanoate, 1,1,3,3-tetramethylbutyl peroxyethylhexanoate, 1,1,2-trimethylpropyl peroxy-2-ethylhexanoate, 1,1,3,3-tetramethylbutyl peroxyisopropyl monocarbonate, 1,1,2-trimethylpropyl peroxyisopropyl monocarbonate, 1,1,3,3-tetramethylbutyl peroxyisononanoate, 1,1,2-trimethylpropyl peroxy-isononanoate, di-tert-butyl peroxide, di-tert-hexyl peroxide, lauroyl peroxide, and dilauroyl peroxide;

[0489] Persulfate compounds such as potassium persulfate;

[0490] Redox polymerization initiator.

[0491] Among the above, the polymerization initiator is preferably at least one selected from azo compounds and organic peroxides from the viewpoint of storage stability and reactivity of methacrylic acid with a copolymerizable monomer.

[0492] The amount of the polymerization initiator used is preferably 0.0001 to 1 part by mass based on 100 parts by mass of the total of methacrylic acid and the monomer copolymerizable with methacrylic acid.

[0493] Examples of the polymerization method for the polymerizable composition include bulk polymerization, solution polymerization, emulsion polymerization, and suspension polymerization.

[0494] The polymerization temperature is preferably 125 to 210° C. This allows for an appropriate polymerization rate. More preferably, the lower limit of the polymerization temperature is 130° C. or higher and the upper limit is 180° C. or lower. The polymerization time is not particularly limited and may be, for example, 0.5 to 24 hours.

[0495] [Methacrylic acid-containing composition of the fifth aspect]

[0496] The methacrylic acid-containing composition of the fifth embodiment contains methacrylic acid, a compound represented by the following formula (51) (component A5), and a polymerization inhibitor (component B). The concentration of methacrylic acid is 98.00 to 99.99% by mass.

[0497]

[0498] In the above formula (51), R 1e and R 2e R each independently represents a hydrogen atom, an alkyl group, an alkenyl group, an aryl group, a hydroxyl group, an alkoxy group, an alkylthio group or an arylthio group. 3e represents a hydrogen atom, an alkyl group, an alkenyl group, an aryl group, a hydroxyl group, an alkoxy group, an amino group, an alkylthio group or an arylthio group. 1e With R 2e , R 2e With R 3e , R 3e With R 1e can be connected to each other to form a ring. 1e With R 2e The total number of carbon atoms is 2 or more.

[0499] Furthermore, the composition containing methacrylic acid may contain other compounds (component C) and water as long as the concentration of methacrylic acid satisfies 98.00 to 99.99% by mass. Each item will be described in detail below.

[0500] (Methacrylic acid)

[0501] The methacrylic acid-containing composition of the fifth embodiment contains methacrylic acid. Methacrylic acid can be produced, for example, as a byproduct of the acetone cyanohydrin (ACH) method or as an intermediate of the C4 direct oxidation method. The methacrylic acid contained in the methacrylic acid-containing composition is preferably produced by the C4 direct oxidation method, and more preferably produced by the C4 direct oxidation method using biomass-derived isobutanol as a starting material.

[0502] (ingredient A5)

[0503] The methacrylic acid-containing composition of the fifth embodiment contains a compound represented by the above formula (51) (component A5). "α hydrogen" means a hydrogen atom bonded to a carbon atom adjacent to the carbon atom of the carbonyl group. The coexistence of component A5 and component B described later can suppress the decomposition of the polymerization inhibitor. The reason for this is presumed to be as follows.

[0504] It is known that methacrylic acid will polymerize due to free radicals generated during storage, and an inhibitor (component B) is added to prevent polymerization. Component B has an anti-polymerization function by capturing free radicals generated during the storage of methacrylic acid, but since the inhibitor decomposes into other compounds when capturing free radicals, the concentration of component B in the composition containing methacrylic acid slowly decreases during storage, resulting in a slow decrease in the anti-polymerization function. In addition, the unwanted decomposition products generated by component B capturing free radicals slowly increase. As an example of free radicals generated during the storage of methacrylic acid, hydroxyl radicals generated by oxygen molecules absorbing ultraviolet light from sunlight can be cited. Component A5 can capture free radical intermediates generated by the reaction of hydroxyl radicals with methacrylic acid and recover methacrylic acid from the intermediate. Therefore, the free radicals that component B needs to capture are reduced, thereby suppressing the reduction in the concentration of component B.

[0505] In addition, when the methacrylic acid composition contains carboxylic acids such as propionic acid and acrylic acid as impurities, the concentration of the carboxylic acid decreases during storage. This is presumably due to decomposition caused by a decarboxylation reaction. Since component A5 is a proton donor, it can donate protons to the anion intermediate generated by the decarboxylation reaction, thereby promoting the decarboxylation reaction.

[0506] The molecular weight of component A5 is preferably 1000 or less. By having a molecular weight of 1000 or less, the number of α hydrogens per unit mass in component A5 can be increased, thereby achieving the effect of the present invention with less mass. The molecular weight of component A5 is more preferably 800 or less, further preferably 600 or less, and particularly preferably 400 or less.

[0507] In the above formula (51), R 1e and R 2e Each independently represents a hydrogen atom, an alkyl group, an alkenyl group, an aryl group, a hydroxyl group, an alkoxy group, an alkylthio group, an arylthio group, or an alkylamino group. 1e and R 2e can be the same or different. In addition, R in the above formula (51) 3e represents a hydrogen atom, an alkyl group, an alkenyl group, an aryl group, a hydroxyl group, an alkoxy group, an amino group, an alkylthio group or an arylthio group. 3e With R 1e and R 3e With R 2e can be the same or different. 1e With R 2e , R 2eWith R 3e , R 3e With R 1e They may be connected to each other to form a ring.

[0508] Generally, the α hydrogen of component A5 has the property of reacting with anions and free radicals, and its reactivity may be reduced depending on the type of substituent it has. 1e , R 2e and R 3e When the above conditions are met, the reactivity of the α hydrogen of component A5 with anions and radicals can be maintained, so the effects of the present invention can be obtained. 1e and R 2e Preferred are hydrogen atoms, alkyl groups having 1 to 5 carbon atoms, alkenyl groups having 2 to 5 carbon atoms, aryl groups having 6 to 12 carbon atoms, hydroxyl groups, alkoxy groups having 1 to 6 carbon atoms, alkylthio groups having 1 to 5 carbon atoms, arylthio groups having 6 to 10 carbon atoms, and alkylamino groups having 0 to 6 carbon atoms. Since these are highly stable substituents, it is possible to prevent component A5 from changing into other compounds during storage. In addition, since the electron donating property is low, the acidity of the α hydrogen of component A5 is increased. R 1e and R 2e More preferred are hydrogen atom, alkyl group having 1 to 5 carbon atoms, aryl group having 6 to 12 carbon atoms, alkoxy group having 1 to 6 carbon atoms, alkylthio group having 1 to 5 carbon atoms, arylthio group having 6 to 10 carbon atoms, and alkylamino group having 0 to 6 carbon atoms. Further preferred are hydrogen atom, alkyl group having 1 to 5 carbon atoms, aryl group having 6 to 12 carbon atoms, alkoxy group having 1 to 6 carbon atoms, and alkylamino group having 0 to 6 carbon atoms. Particularly preferred are hydrogen atom, alkyl group having 1 to 5 carbon atoms, alkoxy group having 1 to 6 carbon atoms, and alkylamino group having 0 to 6 carbon atoms. Even more preferred are hydrogen atom, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, isobutyl group, hydroxyl group, methoxy group, cyclohexyl group, and N,N-dimethylamino group. Most preferred are hydrogen atom, methyl group, ethyl group, n-propyl group, isopropyl group, hydroxyl group, methoxy group, cyclohexyl group, and N,N-dimethylamino group.

[0509] In addition, R 3e More preferably, it is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, an aryl group having 6 to 12 carbon atoms, a hydroxyl group, an alkoxy group having 1 to 6 carbon atoms, an amino group having 0 to 6 carbon atoms, an alkylthio group having 1 to 5 carbon atoms, or an arylthio group having 6 to 10 carbon atoms. Since these are highly stable substituents, they can prevent component A5 from changing into other compounds during storage. 3eMore preferred are hydrogen atoms, alkyl groups having 1 to 5 carbon atoms, alkenyl groups having 2 to 5 carbon atoms, hydroxyl groups or alkoxy groups having 1 to 6 carbon atoms, and amino groups having 0 to 6 carbon atoms; further preferred are hydrogen atoms, alkyl groups having 1 to 5 carbon atoms, alkenyl groups having 2 to 5 carbon atoms, amino groups having 0 to 6 carbon atoms, and hydroxyl groups; particularly preferred are hydrogen atoms, methyl groups, ethyl groups, n-propyl groups or isopropyl groups, isopropenyl groups, and hydroxyl groups; and most preferred are hydrogen atoms, methyl groups, isopropyl groups, and hydroxyl groups.

[0510] The alkyl group is a chain (straight or branched) alkyl group or a cyclic alkyl group. In the case of a chain alkyl group, a chain alkyl group having 1 to 20 carbon atoms is preferred, a chain alkyl group having 1 to 10 carbon atoms is more preferred, and a chain alkyl group having 1 to 5 carbon atoms is further preferred. As chain alkyl groups, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, hexyl, octyl, decyl, hydroxymethyl, 1-hydroxyethyl, 2-hydroxyethyl, etc. can be cited, and methyl, ethyl, n-propyl, isopropyl can be cited. In addition, in the case of a cyclic alkyl group, a cyclic alkyl group having 3 to 20 carbon atoms is preferred, a cyclic alkyl group having 4 to 10 carbon atoms is more preferred, and a cyclic alkyl group having 5 to 7 carbon atoms is further preferred. As cyclic alkyl groups, for example, cyclopentyl, cyclohexyl, cyclooctyl, etc. can be cited.

[0511] The alkenyl group is a chain (straight or branched) alkenyl group or a cyclic alkenyl group. In the case of a chain alkenyl group, a chain alkenyl group having 2 to 20 carbon atoms is preferred, a chain alkenyl group having 2 to 10 carbon atoms is more preferred, and a chain alkenyl group having 2 to 5 carbon atoms is further preferred. Examples of chain alkenyl groups include vinyl, 1-propenyl, isopropenyl, 2-butenyl, 1,3-butadienyl, 2-pentenyl, and 2-hexenyl. In the case of a cyclic alkenyl group, a cyclic alkenyl group having 3 to 20 carbon atoms is preferred, a cyclic alkenyl group having 4 to 10 carbon atoms is more preferred, and a cyclic alkenyl group having 5 to 7 carbon atoms is further preferred. Examples of cyclic alkenyl groups include cyclopentenyl and cyclohexenyl.

[0512] The alkoxy group is preferably an alkoxy group having 1 to 20 carbon atoms, more preferably an alkoxy group having 1 to 10 carbon atoms, and further preferably an alkoxy group having 1 to 6 carbon atoms. Examples of the alkoxy group include methoxy, ethoxy, butoxy, and phenoxy.

[0513] Amino groups include amino groups with no substituent on the nitrogen atom (-NH 2 ) (carbon number 0), and an amino group in which a part or all of the hydrogen atoms bonded to the nitrogen atom are substituted with carbon atoms. The number of carbon atoms of the amino group in which a part or all of the hydrogen atoms bonded to the nitrogen atom are substituted with carbon atoms is preferably 1 to 20, more preferably 1 to 10, and further preferably 1 to 6. Examples of the amino group include an unsubstituted amino group (—NH2 ), methylamino, ethylamino, propylamino, butylamino, dimethylamino, diethylamino, aniline, toluidine, anisidine, diphenylamino, N-methyl-N-phenylamino, etc.

[0514] The alkylthio group is preferably an alkylthio group having 1 to 20 carbon atoms, more preferably an alkylthio group having 1 to 10 carbon atoms, and further preferably an alkylthio group having 1 to 5 carbon atoms. Examples of the alkylthio group include methylthio, ethylthio, propylthio, and isopropylthio.

[0515] The arylthio group is preferably an arylthio group having 1 to 20 carbon atoms, more preferably an arylthio group having 3 to 10 carbon atoms, and further preferably an arylthio group having 6 to 10 carbon atoms. Examples of the arylthio group include a phenylthio group and a tolylthio group.

[0516] The aryl group is preferably an aryl group having 1 to 20 carbon atoms, and more preferably an aryl group having 1 to 12 carbon atoms. The aryl group includes a heteroaryl group containing oxygen, nitrogen, sulfur, and the like. Examples of the aryl group include phenyl, mesityl, naphthyl, 2-methylphenyl, 3-methylphenyl, 4-methylphenyl, 2,3-dimethylphenyl, 2,4-dimethylphenyl, 2,5-dimethylphenyl, 2,6-dimethylphenyl, 2-ethylphenyl, isothiophenyl, 2-thiophenyl, 2-ethylphenyl, 2-isothio ... Azolyl, isothiazolyl, imidazolyl, oxazolyl, thiazolyl, thiadiazolyl, thienyl, triazolyl, tetrazolyl, pyridyl, pyrazinyl, pyrimidinyl, pyridazinyl, pyrazolyl, pyrrolyl, furanyl, furazanyl, isoquinolyl, isoindolyl, indolyl, quinolyl, pyridothiazolyl, benzimidazolyl, benzo oxazolyl, benzothiazolyl, benzotriazolyl, benzofuranyl, imidazopyridinyl, triazolopyridinyl, purinyl.

[0517] R 1e With R 2e , R 2e With R 3e , R 3e With R 1e They may be connected to each other to form a ring. 1e With R 2e Examples of compounds that are linked to form a ring include cyclohexanecarboxylic acid, cyclohexanecarboxylic acid methyl ester, cyclopentanecarboxylic acid, and cyclopentanecarboxylic acid methyl ester. 2e With R 3e The compound connected to form a ring and R 3e With R 1e Examples of the compound linked to form a ring include 2,5-dimethyl-2-cyclopenten-1-one, 2-methyl-5-isopropyl-1-cyclohexanone, α-methyl-δ-valerolactone, and α-methyl-γ-butyrolactone.

[0518] Among the compounds satisfying the above conditions, from the viewpoint of quality stability of the methacrylic acid-containing composition during storage, component A5 is preferably isobutyric acid, isovaleric acid, 2-methylbutyric acid, acetonylacetone, 3-methyl-3-butene-2-one, isobutyraldehyde, cyclohexanecarboxylic acid, 2-methoxypropionic acid, N,N-dimethylglycine, malonic acid, methylthioacetic acid, 3-butenoic acid, butyric acid, palmitic acid, stearic acid, methyl isobutyrate, ethyl isobutyrate, isobutyl isobutyrate, isoamyl isobutyrate, phenyl isobutyrate, methyl butyrate, methyl isovaleric acid, methyl isopropyl ketone, 3-hexen-2-one, 2,5-dimethyl-2-cyclopentene-1-one, 2-methyl-5-isopropyl-1-cyclohexanone, 2-acetylfuran, butyraldehyde, 2-methylbutyraldehyde, 3-methylbutyraldehyde, (R)-(- )-3-hydroxyisobutyric acid, cyclopentanecarboxylic acid, α-methyl-δ-valerolactone, or α-methyl-γ-butyrolactone, more preferably isobutyric acid, isovaleric acid, 2-methylbutyric acid, acetonylacetone, 3-methyl-3-butene-2-one, isobutyraldehyde, cyclohexanecarboxylic acid, 2-methoxypropionic acid, N,N-dimethylglycine, malonic acid, methylthioacetic acid, 3-butenoic acid, and methylisopropenyl ketone, further preferably isobutyric acid, isovaleric acid, 2-methylbutyric acid, 2-methoxypropionic acid, N,N-dimethylglycine, acetonylacetone, 3-methyl-3-butene-2-one, isobutyraldehyde, and methylisopropenyl ketone, and particularly preferably isobutyric acid, isovaleric acid, 2-methylbutyric acid, acetonylacetone, isopropenylmethyl ketone, isobutyraldehyde, cyclohexanecarboxylic acid, 2-methoxypropionic acid, and N,N-dimethylglycine.

[0519] Component A5 may be used in one kind or in two or more kinds.

[0520] (ingredient B)

[0521] The composition containing methacrylic acid in the fifth embodiment contains a polymerization inhibitor (component B). In the present specification, a polymerization inhibitor refers to a compound having the function of inhibiting the polymerization reaction of methacrylic acid. As the polymerization inhibitor, for example, phenolic compounds, quinone compounds, nitrobenzene compounds, N-oxyl radical compounds, amine compounds, phosphorus-containing compounds, sulfur-containing compounds, iron-containing compounds, copper-containing compounds and manganese-containing compounds can be cited. By containing component B, the polymerization reaction of methacrylic acid based on the free radical polymerization mechanism during the storage of methacrylic acid can be inhibited. In addition, as described above, by the coexistence of component A5 and component B, the reduction of component B can be effectively suppressed.

[0522] Examples of the polymerization inhibitor as a phenolic compound include alkylphenols, hydroxyphenols, aminophenols, nitrophenols, nitrosophenols, alkoxyphenols, and tocopherol.

[0523] Examples of the alkylphenol include o-cresol, m-cresol, p-cresol, 2-tert-butyl-4-methylphenol, 2,4-dimethyl-6-tert-butylphenol, 2,6-di-tert-butyl-4-methylphenol, 2-tert-butylphenol, 4-tert-butylphenol, 2,4-di-tert-butylphenol, 2-methyl-4-tert-butylphenol, 4-tert-butyl-2,6-dimethylphenol, 2,2′-methylenebis(4-ethyl-6-tert-butylphenol), 4,4′-thiobis(3-methyl-6-tert-butylphenol), and 3,5-di-tert-butyl-4-hydroxytoluene.

[0524] Examples of the hydroxyphenol include hydroquinone, 2-methylhydroquinone, 2-tert-butylhydroquinone, 2,5-di-tert-butylhydroquinone, 2,6-di-tert-butylhydroquinone, 2,5-di-tert-amylhydroquinone, 2-tert-butylmethoxyhydroquinone, 2,3,5-trimethylhydroquinone, 2,5-dichlorohydroquinone, 1,2-dihydroxybenzene, 2-acetylhydroquinone, 4-methylcatechol, 4-tert-butylcatechol, 2-methylresorcinol, 4-methylresorcinol, and 2,3-dihydroxyacetophenone.

[0525] Examples of the aminophenol include o-aminophenol, m-aminophenol, p-aminophenol, 2-(N,N-dimethylamino)phenol, and 4-(ethylamino)phenol.

[0526] Examples of the nitrophenol include o-nitrophenol, m-nitrophenol, p-nitrophenol, and 2,4-dinitrophenol.

[0527] Examples of the nitrosophenol include o-nitrosophenol, m-nitrosophenol, p-nitrosophenol, and α-nitroso-β-naphthol.

[0528] Examples of the alkoxyphenol include 2-methoxyphenol, 2-ethoxyphenol, 2-isopropoxyphenol, 2-tert-butoxyphenol, 4-methoxyphenol, 4-ethoxyphenol, 4-propoxyphenol, 4-butoxyphenol, 4-tert-butoxyphenol, 4-heptyloxyphenol, hydroquinone monobenzyl ether, tert-butyl-4-methoxyphenol, di-tert-butyl-4-methoxyphenol, pyrogallol-1,2-dimethyl ether, and hydroquinone monobenzoate.

[0529] Examples of the tocopherol include α-tocopherol and 2,3-dihydro-2,2-dimethyl-7-hydroxybenzofuran.

[0530] Examples of the polymerization inhibitor as a quinone compound include p-benzoquinone, chloro-p-benzoquinone, 2,5-dichloro-p-benzoquinone, 2,6-dichloro-p-benzoquinone, tetrachloro-p-benzoquinone, tetrabromo-p-benzoquinone, 2,3-dimethyl-p-benzoquinone, 2,5-dimethyl-p-benzoquinone, methoxy-p-benzoquinone, and methyl-p-benzoquinone.

[0531] Examples of the polymerization inhibitor as a nitrobenzene compound include nitrobenzene, o-dinitrobenzene, m-dinitrobenzene, p-dinitrobenzene, 2,4-dinitrobenzene, dinitrodurene, and 2,2-diphenyl-1-picrylhydrazyl.

[0532] Examples of the polymerization inhibitor as an N-oxyl radical compound include 4-hydroxy-2,2,6,6-tetramethyl-piperidin-N-oxyl radical, 4-oxo-2,2,6,6-tetramethyl-piperidin-N-oxyl radical, 4-acetoxy-2,2,6,6-tetramethyl-piperidin-N-oxyl radical, 2,2,6,6-tetramethyl-piperidin-N-oxyl radical, piperidine-1-oxyl radical, 4-(dimethylamino)-2,2,6,6-tetramethyl-piperidin-N-oxyl radical, 4-amino-2,2,6,6-tetramethyl-piperidin-N-oxyl radical, 4-vinyloxy-2,2,6,6-tetramethyl-piperidin-N-oxyl radical, 4-benzoyloxy-2,2,6,6-tetramethyl-piperidin-N-oxyl radical, -N-oxyl free radical, 2,2,5,5-tetramethyl-piperidinyl-N-oxyl free radical, 3-amino-2,2,5,5-tetramethyl-piperidinyl-N-oxyl free radical, 4,4',4"-tris(2,2,6,6-tetramethyl-piperidinyl-N-oxyl free radical)phosphite, 3-oxo-2,2,5,5-tetramethylpyrrolidine-N-oxyl free radical, pyrrolidine-1-oxyl free radical, 2,2,5,5-tetramethyl-1-oxa-3-azacyclopentyl-3-oxyl free radical, 2,2,5,5-tetramethyl-3-pyrrolinyl-1-oxyl-3-carboxylic acid, 2,2,3,3,5,5,6,6-octamethyl-1,4-diazacyclohexyl-1,4-dioxyl free radical, di-tert-butylnitroxide, di-tert-amylnitroxide, etc.

[0533] Examples of the polymerization inhibitor as an amine compound include N,N-diphenylamine, alkylated diphenylamine, 4,4'-dicumyldiphenylamine, 4,4'-dioctyldiphenylamine, 4-aminodiphenylamine, p-nitrosodiphenylamine, N-nitrosodinaphthylamine, N-nitrosodiphenylamine, N-nitrosophenylnaphthylamine, N-nitrosophenylhydroxylamine, N,N'-dialkyl-p-phenylenediamine (the alkyl groups may be the same or different, each independently having 1 to 4 carbon atoms, and may be linear or branched), N,N'-diphenyl-p-phenylenediamine, N-phenyl-N'-isopropyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-1,4-phenylenediamine, N,N'-di-2-naphthylamine, 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline, 2,2,4-trimethyl-1,2-dihydroquinoline polymer, butyral-α-naphthylamine, N-phenyl-β-naphthylamine, 4-hydroxy-2,2,6,6-tetramethylpiperidine, 4-benzoyloxy-2,2,6,6-tetramethylpiperidine, 1,4-dihydroxy-2,2,6,6-tetramethylpiperidine, 1-hydroxy-4-benzoyloxy-2,2,6,6-tetramethylpiperidine, etc.

[0534] Examples of the polymerization inhibitor as a phosphorus-containing compound include triphenylphosphine, triphenyl phosphite, triethyl phosphite, tris(isodecyl) phosphite, tris(tridecyl) phosphite, phenyl diisooctyl phosphite, phenyl diisodecyl phosphite, phenyl di(tridecyl) phosphite, diphenyl isooctyl phosphite, diphenyl isodecyl phosphite, diphenyl tridecyl phosphite, [1,1-diphenyl-4,4'-diyl-bis[tetrakis-2,4-bis(1,1-dimethylethyl)phenyl]]phosphonate, tris(nonylphenyl) phosphite, 4,4'-isopropylidene diphenol alkyl phosphite, tris(2,4-di-tert-butylphenyl) phosphite, and terphenyl phosphite. Ester, distearyl pentaerythritol diphosphite, di(2,4-di-tert-butylphenyl) pentaerythritol diphosphite, di(nonylphenyl) pentaerythritol diphosphite, phenyl bisphenol A pentaerythritol diphosphite, tetra(tridecyl)-4,4'-butylidene bis(3-methyl-6-tert-butylphenol) diphosphite, hexa(tridecyl)-1,1,3-tri(2-methyl-4-hydroxy-5-tert-butylphenyl) butane triphosphite, 3,5-di-tert-butyl-4-hydroxybenzyl phosphate diethyl ester, bis(4-tert-butylphenyl) phosphate sodium salt, 2,2'-methylene-bis(4,6-di-tert-butylphenyl) phosphate sodium salt, 1,3-bis(diphenoxyphosphoryloxy)benzene, etc.

[0535] Examples of the polymerization inhibitor as a sulfur-containing compound include diphenyl sulfide, phenothiazine, 3-oxophenothiazine, 5-oxophenothiazine, phenothiazine dimer, 1,4-dimercaptobenzene, 1,2-dimercaptobenzene, 2-mercaptophenol, 4-mercaptophenol, 2-(methylthio)phenol, and 3,7-bis(dimethylamino)phenothiazine. Chloride, sulfur (elemental), etc.

[0536] Examples of the polymerization inhibitor as an iron-containing compound include iron (III) chloride and the like.

[0537] Examples of the polymerization inhibitor as a copper compound include copper dimethyldithiocarbamate, copper diethyldithiocarbamate, copper dibutyldithiocarbamate, copper salicylate, copper acetate, copper thiocyanate, copper nitrate, copper chloride, copper carbonate, copper hydroxide, copper acrylate, copper methacrylate, and the like.

[0538] Examples of the polymerization inhibitor as a manganese-containing compound include manganese dialkyldithiocarbamate (the alkyl group is any of methyl, ethyl, propyl and butyl, and may be the same or different), manganese diphenyldithiocarbamate, manganese formate, manganese acetate, manganese octoate, manganese naphthenate, manganese permanganate, and manganese salt of ethylenediaminetetraacetic acid.

[0539] Among the above, from the viewpoint of quality stability of the composition containing methacrylic acid during storage, component B is preferably at least one polymerization inhibitor selected from phenolic compounds, N-oxyl radical compounds, amine compounds, phosphorus-containing compounds and sulfur-containing compounds, and for example, preferably at least one polymerization inhibitor selected from hydroquinone, 4-methoxyphenol, 2,4-dimethyl-6-tert-butylphenol, 2,6-di-tert-butyl-4-methylphenol, 4-hydroxy-2,2,6,6-tetramethylpiperidinyl-N-oxyl radical, N,N-diphenylamine, N-nitrosodiphenylamine, triphenyl phosphite and phenothiazine. Component B is more preferably a phenolic compound, and for example, more preferably at least one polymerization inhibitor selected from hydroquinone, 4-methoxyphenol, 2,4-dimethyl-6-tert-butylphenol and 2,6-di-tert-butyl-4-methylphenol. Component B is particularly preferably at least one polymerization inhibitor selected from hydroquinone and 4-methoxyphenol.

[0540] Component B may be one kind or two or more kinds.

[0541] When the composition containing methacrylic acid contains a compound corresponding to both component A5 and component B, the compound is regarded as component B. That is, the composition containing methacrylic acid needs to contain component A5 different from the compound. When two or more compounds corresponding to both component A5 and component B are contained, the compound with the highest molar concentration in the methacrylic acid composition is regarded as component B, and the other compounds are regarded as component A5.

[0542] (Concentration of Component A5 and Component B)

[0543] The concentration of component A5 is considered as M A5 (μmol / L), the concentration of component B is considered as M B (μmol / L), M B / M A5 It is preferably 0.005 to 100. From the viewpoint of the efficiency of inhibiting the production of pyruvic acid, M B / M A5 The lower limit is 0.05 or more, and the upper limit is more preferably 10 or less.

[0544] M A5 It is preferably 1 to 40000 μmol / L. A5 When the concentration of M is 1 μmol / L or more, the effect of inhibiting the decomposition of the polymerization inhibitor can be fully obtained. A5 When the concentration is 40000 μmol / L or less, the amount of impurities in producing a methacrylic acid polymer by polymerizing the methacrylic acid-containing composition of the fifth embodiment can be reduced, thereby preventing adverse effects on the physical properties of the polymer. A5 The lower limit of M is more preferably 10 μmol / L or more, further preferably 30 μmol / L or more, further preferably 50 μmol / L or more, further preferably 55 μmol / L or more. A3 The upper limit is more preferably 3000 μmol / L or less, further preferably 25000 μmol / L or less, and particularly preferably 20000 μmol / L or less.

[0545] M B It is preferably 1 to 50000 μmol / L. B When the concentration of M is 1 μmol / L or more, the effect of inhibiting the generation of methacrylic acid dimers and pyruvic acid can be fully obtained. B When the concentration is 50000 μmol / L or less, the amount of impurities in producing a methacrylic acid polymer by polymerizing the methacrylic acid-containing composition of the fifth embodiment can be reduced, thereby preventing adverse effects on the physical properties of the polymer. B The lower limit of M is more preferably 10 μmol / L or more, further preferably 100 μmol / L or more, particularly preferably 1500 μmol / L or more, and even more preferably 2000 μmol / L or more. B The upper limit is more preferably 45000 μmol / L or less, further preferably 40000 μmol / L or less, particularly preferably 35000 μmol / L or less, even more preferably 30000 μmol / L or less, and most preferably 25000 μmol / L or less.

[0546] (Methacrylic acid concentration)

[0547] The methacrylic acid concentration of the methacrylic acid-containing composition of the fifth embodiment is 98.00 to 99.99% by mass. When the methacrylic acid concentration is 98.00% by mass or more, the amount of impurities when the methacrylic acid polymer is produced by polymerization of the methacrylic acid-containing composition of the fifth embodiment can be reduced, and the physical properties of the polymer can be prevented from being adversely affected. In addition, by setting the methacrylic acid concentration to 99.99% by mass or less, the purification cost can be reduced. The lower limit of the methacrylic acid concentration is more preferably 98.50% or more, further preferably 99.00% or more, particularly preferably 99.50% or more, and most preferably 99.80% or more by mass.

[0548] (Ingredient C)

[0549] The composition containing methacrylic acid of the fifth embodiment may further contain component C as another compound as long as the concentration of methacrylic acid is 98.00 to 99.99% by mass. Examples of component C include impurities generated in the production process of methacrylic acid. For example, methacrylic acid may contain diacetyl as an impurity. From the viewpoint of reducing the coloration of the composition containing methacrylic acid, the concentration of diacetyl is preferably 55 μmol / L or less, more preferably 20 μmol / L or less, further preferably 10 μmol / L or less, and particularly preferably 1 μmol / L or less.

[0550] (Analysis of Compositions Containing Methacrylic Acid)

[0551] The fact that the composition containing methacrylic acid contains component A5, component B, component C, and water can be confirmed by, for example, GC-MS measurement. In the GC-MS spectrum of the composition containing methacrylic acid, if there is a peak at the same retention time as the standard of component A5, and the m / z value detected in the mass spectrum of the peak is consistent with the accurate mass of component A5, it can be determined that the composition containing methacrylic acid contains component A5. In the case where a standard of component A5 is not available, when the pattern of the mass spectrum of the peak appearing in the GC-MS spectrum of the composition containing methacrylic acid is consistent with the pattern of the mass spectrum of component A5 included in the mass spectrum database, it can be determined that the peak is the component A5 peak. That is, it can be determined that the composition containing methacrylic acid contains component A5. Examples of mass spectrum databases include NIST20, NIST17, NIST14, and NIST14s. In addition, when the volatility is low and cannot be detected by GC-MS measurement, LC-MS can be used for detection. Component B, component C, and water can also be confirmed by the same method as component A1.

[0552] In addition, the concentration of methacrylic acid can be calculated by, for example, performing GC-FID measurement on a composition containing methacrylic acid, quantifying it using the area percentage method, and correcting it using the amount of water quantified by a Karl Fischer titrator. The concentration of component A5 can be quantified by, for example, performing GC measurement on a composition containing methacrylic acid and using an internal standard method. If a standard product of component A5 is not available and quantification cannot be performed using the internal standard method, an organic compound with a known concentration can be subjected to GC-FID measurement under the same conditions as the composition containing methacrylic acid, and the concentration of component A5 can be calculated using the following formula.

[0553]

[0554] Here, N is the number of carbon atoms in one molecule of an organic compound of known concentration. A5 is the number of carbon atoms in one molecule of component A5, S A5 is the peak area of ​​component A5, S is the peak area of ​​the organic compound of known concentration, and M is the concentration (μmol / L) of the organic compound of known concentration.

[0555] When volatility is low and quantification by GC is not possible, quantification can be performed by chromatography such as LC.

[0556] The concentrations of Component B and Component C can also be calculated by the same method as that of Component A5 described above.

[0557] In addition, the presence of water in the composition containing methacrylic acid and the concentration of water can be confirmed by Karl Fischer method.

[0558] [Method for producing a composition containing methacrylic acid]

[0559] As a method for producing a composition containing methacrylic acid in the fifth embodiment, there can be mentioned a method of adding component A5 and component B to methacrylic acid. Methacrylic acid can use a commercial product, or methacrylic acid produced by a known method such as the acetone cyanohydrin (ACH) method and the C4 direct oxidation method. Component A5 and component B can use a commercial product, or a compound synthesized by a known method. In the case of using a substance produced by a known method such as the acetone cyanohydrin (ACH) method and the C4 direct oxidation method for methacrylic acid, component A5 or component B can also be added in the middle of the raw material or the production process to produce a composition containing methacrylic acid. In addition, in the case where component A5 or component B is generated as a by-product in the methacrylic acid production process, a composition containing methacrylic acid can be produced by leaving a portion of the generated component A5 or component B.

[0560] [Evaluation method of storage stability and thermal stability]

[0561] The fifth embodiment has high quality stability during storage of the composition containing methacrylic acid. As an evaluation method for the quality stability of the composition containing methacrylic acid during storage, for example, a method of actually storing the composition containing methacrylic acid for a long time and confirming the reduction in the amount of the polymerization inhibitor can be cited. In addition, from the perspective of simplicity of operation, a method of heating the composition containing methacrylic acid for a short time and confirming the reduction in the amount of the polymerization inhibitor can be used. When heating for a short time, the heating temperature is preferably 50 to 100°C, and the heating time is preferably 1 to 24 hours. In the fifth embodiment, the quality stability of the composition containing methacrylic acid during storage is evaluated based on the reduction in the amount of the polymerization inhibitor when the composition containing methacrylic acid is stored at 25°C for 21 days.

[0562] [Method for producing methacrylate]

[0563] The method for producing a methacrylic acid ester of the fifth aspect includes the step of esterifying the methacrylic acid-containing composition of the fifth aspect.

[0564] The alcohol to be reacted with the composition containing methacrylic acid is not particularly limited, and examples thereof include methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, and the like. Examples of the methacrylic acid esters obtained include methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, butyl methacrylate, and isobutyl methacrylate. The esterification reaction may be carried out in the presence of an acidic catalyst such as a sulfonic acid type cation exchange resin. The temperature in the esterification reaction is preferably 50 to 200°C.

[0565] The pressure during the esterification reaction, the position of the catalyst in the reactor, the ratio of the catalyst in the reactor, and the like are not particularly limited, and commonly used methods can be applied.

[0566] [Fifth aspect of the method for producing a methacrylic acid polymer]

[0567] The method for producing a methacrylic acid polymer of the present invention includes a step of polymerizing a polymerizable composition containing the methacrylic acid-containing composition of the present invention.

[0568] The polymerizable composition may contain a monomer copolymerizable with methacrylic acid and other additives as necessary.

[0569] Examples of the monomer copolymerizable with methacrylic acid include the following monomers.

[0570] Methacrylates such as ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, 2-ethylhexyl methacrylate, phenyl methacrylate, or benzyl methacrylate;

[0571] Acrylates such as methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, tert-butyl acrylate, or 2-ethylhexyl acrylate;

[0572] Unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, or itaconic acid;

[0573] Unsaturated carboxylic anhydrides such as maleic anhydride or itaconic anhydride;

[0574] Maleimides such as N-phenylmaleimide or N-cyclohexylmaleimide;

[0575] A vinyl monomer containing a hydroxyl group, such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, or 2-hydroxypropyl methacrylate;

[0576] Vinyl esters such as vinyl acetate or vinyl benzoate;

[0577] Vinyl chloride, vinylidene chloride and their derivatives;

[0578] Nitrogen-containing vinyl monomers such as methacrylamide or acrylonitrile;

[0579] Monomers containing epoxy groups such as glycidyl acrylate or glycidyl methacrylate;

[0580] Aromatic vinyl monomers such as styrene or α-methylstyrene;

[0581] Alkanediol di(meth)acrylates such as ethylene glycol di(meth)acrylate, 1,2-propylene glycol di(meth)acrylate, 1,3-butylene glycol di(meth)acrylate, or 1,6-hexanediol di(meth)acrylate;

[0582] Polyoxyalkylene glycol di(meth)acrylates such as diethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, triethylene glycol (meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, or neopentyl glycol di(meth)acrylate;

[0583] Vinyl monomers having two or more ethylenically unsaturated bonds in the molecule, such as divinylbenzene;

[0584] An unsaturated polyester prepolymer obtained from at least one polycarboxylic acid including an ethylenically unsaturated polycarboxylic acid and at least one diol;

[0585] A vinyl ester prepolymer obtained by modifying the epoxy group terminal with acrylic acid.

[0586] Among the above, the monomer copolymerizable with methacrylic acid is preferably at least one selected from methacrylic acid esters and acrylates. The monomer copolymerizable with methacrylic acid is more preferably methacrylic acid ester, and particularly preferably methyl methacrylate.

[0587] The monomer copolymerizable with methacrylic acid may be one kind or two or more kinds.

[0588] In the polymerizable composition, the content of the monomer copolymerizable with methacrylic acid is preferably 50.00 to 99.99 parts by mass relative to 100 parts by mass of the polymerizable composition. The lower limit of the content of the monomer copolymerizable with methacrylic acid is more preferably 60 parts by mass or more, further preferably 70 parts by mass or more, particularly preferably 80 parts by mass or more, and most preferably 90 parts by mass or more, relative to 100 parts by mass of the polymerizable composition. The upper limit of the content of the monomer copolymerizable with methacrylic acid is more preferably 99.9 parts by mass or less, further preferably 99 parts by mass or less, relative to 100 parts by mass of the polymerizable composition.

[0589] As other additives, polymerization initiators are preferred. In addition, the polymerizable composition may contain chain transfer agents, mold release agents, lubricants, plasticizers, antioxidants, antistatic agents, light stabilizers, ultraviolet absorbers, flame retardants, flame retardant aids, polymerization inhibitors, fillers, pigments, dyes, silane coupling agents, leveling agents, defoamers, fluorescent agents, etc. as needed. The other additives may be one or more.

[0590] Examples of the polymerization initiator include the following compounds.

[0591] Azo compounds such as 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), 2,2'-azobis(2-methylpropionitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2,4,4-trimethylpentane), 2,2'-azobis(2-methylpropane), 1,1-azobis(cyclohexanecarbonitrile), and 2,2'-azobisisobutyric acid dimethyl ester;

[0592] Benzoyl peroxide, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, 1,1-bis(tert-butylperoxy)cyclohexane, 1,1-bis(tert-butylperoxy)-3,5,5-trimethylcyclohexane, tert-butyl peroxy-2-ethylhexanoate, tert-butyl peroxyisobutyrate, tert-butyl peroxybenzoate, tert-hexyl peroxybenzoate, tert-butyl peroxyisopropyl monocarbonate, tert-butyl peroxy-3,5,5-trimethylhexanoate, tert-butyl peroxylaurate, tert-butyl peroxyacetate, tert-hexyl peroxyisopropyl monocarbonate, tert-ethyl peroxy Organic peroxides such as tert-hexyl hexanoate, tert-amyl peroxy-2-ethylhexanoate, 1,1,3,3-tetramethylbutyl peroxyethylhexanoate, 1,1,2-trimethylpropyl peroxy-2-ethylhexanoate, 1,1,3,3-tetramethylbutyl peroxyisopropyl monocarbonate, 1,1,2-trimethylpropyl peroxyisopropyl monocarbonate, 1,1,3,3-tetramethylbutyl peroxyisononanoate, 1,1,2-trimethylpropyl peroxy-isononanoate, di-tert-butyl peroxide, di-tert-hexyl peroxide, lauroyl peroxide, and dilauroyl peroxide;

[0593] Persulfate compounds such as potassium persulfate;

[0594] Redox polymerization initiator.

[0595] Among the above, the polymerization initiator is preferably at least one selected from azo compounds and organic peroxides from the viewpoint of storage stability and reactivity of methacrylic acid with a copolymerizable monomer.

[0596] The amount of the polymerization initiator used is preferably 0.0001 to 1 part by mass based on 100 parts by mass of the total of methacrylic acid and the monomer copolymerizable with methacrylic acid.

[0597] Examples of the polymerization method for the polymerizable composition include bulk polymerization, solution polymerization, emulsion polymerization, and suspension polymerization.

[0598] The polymerization temperature is preferably 125 to 210° C. This allows for an appropriate polymerization rate. More preferably, the lower limit of the polymerization temperature is 130° C. or higher and the upper limit is 180° C. or lower. The polymerization time is not particularly limited and may be, for example, 0.5 to 24 hours.

[0599] [Methacrylic acid-containing composition of the sixth aspect]

[0600] The methacrylic acid-containing composition of the sixth embodiment contains methacrylic acid, a compound represented by the following formula (61) (component A6), and a polymerization inhibitor (component B). The concentration of methacrylic acid is 98.00 to 99.99% by mass.

[0601]

[0602] In formula (61), R 1f , R 2f and R 3f R each independently represents a hydrogen atom, an alkyl group, an alkenyl group, an aryl group, a hydroxyl group, an alkoxy group, an amino group, an alkylthio group or an arylthio group. 4f represents an alkyl group, an alkenyl group, an aryl group, a hydroxyl group, an alkoxy group, an amino group, a monovalent group containing a carbonyl group, an alkylthio group or an arylthio group. 1f =H, R 2f =H, R 3f =CH 3 And R 4f =OH, that is, when the compound represented by formula (61) is methacrylic acid, H represents a hydrogen atom, C represents a carbon atom, and O represents an oxygen atom.

[0603] Furthermore, the composition containing methacrylic acid may contain other compounds (component C) and water as long as the concentration of methacrylic acid satisfies 98.00 to 99.99% by mass. Each item will be described in detail below.

[0604] (Methacrylic acid)

[0605] The methacrylic acid-containing composition of the sixth embodiment contains methacrylic acid. Methacrylic acid can be produced, for example, as a byproduct of the acetone cyanohydrin (ACH) method or as an intermediate of the C4 direct oxidation method. The methacrylic acid contained in the methacrylic acid-containing composition is preferably produced by the C4 direct oxidation method, and more preferably produced by the C4 direct oxidation method using biomass-derived isobutyl alcohol as a starting material.

[0606] (ingredient A6)

[0607] The methacrylic acid-containing composition of the sixth embodiment contains a compound (component A6) represented by the above formula (61). The coexistence of component A6 and component B described later can suppress the decomposition of the polymerization inhibitor during storage of the methacrylic acid-containing composition. In addition, when the methacrylic acid-containing composition contains impurities such as acrylic acid and propionic acid, the decomposition thereof can be promoted to reduce the impurity concentration. The reason for this is presumed to be as follows.

[0608] It is known that methacrylic acid will polymerize due to free radicals generated during storage, and an inhibitor (component B) is added to prevent polymerization. Component B has an anti-polymerization function by capturing free radicals generated during the storage of methacrylic acid, but since the inhibitor decomposes into other compounds when capturing free radicals, the concentration of component B in the composition containing methacrylic acid during storage slowly decreases, resulting in a slow decrease in the anti-polymerization function. In addition, the unwanted decomposition products generated by component B capturing free radicals slowly increase. As an example of free radicals generated during the storage of methacrylic acid, hydroxyl radicals generated by oxygen molecules absorbing ultraviolet light from sunlight can be cited. In addition, hydroxyl radicals can also become the cause of pyruvic acid generation due to the oxidation of methacrylic acid. Component A6 absorbs ultraviolet light due to its conjugated double bonds, and its absorption wavelength varies depending on the type of substituent. And component A6 can absorb ultraviolet light of a wide range of wavelengths. Therefore, when the composition containing methacrylic acid contains component A6, ultraviolet light of a wide range of wavelengths is absorbed to suppress the generation of hydroxyl radicals. Therefore, the free radicals that component B needs to capture are reduced, thereby suppressing the reduction in the concentration of component B. Among various organic compounds that absorb ultraviolet light, component A6 has a molecular structure similar to methacrylic acid. Therefore, when a composition containing methacrylic acid is used as a raw material to produce a polymer, the adverse effects of component A6 contained as an impurity can be reduced.

[0609] The molecular weight of component A6 is preferably 1000 or less. By having a molecular weight of 1000 or less, the number of conjugated double bonds per unit mass in component A6 can be increased, and the effect of the present invention can be obtained with less mass. The molecular weight of component A6 is more preferably 800 or less, further preferably 600 or less, and particularly preferably 400 or less.

[0610] In the above formula (61), R 1f , R 2f and R 3f Each independently represents a hydrogen atom, an alkyl group, an alkenyl group, an aryl group, a hydroxyl group, an alkoxy group, an amino group, an alkylthio group or an arylthio group. 4f R represents an alkyl group, an alkenyl group, an aryl group, a hydroxyl group, an alkoxy group, an amino group, a monovalent group including a carbonyl group, an alkylthio group or an arylthio group. 1f , R 2f , R 3f and R 4f They may be the same or different.

[0611] R 1f , R 2f , R 3f and R 4f When the above conditions are met, the π-conjugated system of component A6 can be maintained, so that the component A6 can have the property of absorbing ultraviolet light in a wide range of wavelengths, and the effects of the present invention can be obtained.1f , R 2f and R 3f Preferably, it is a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, a hydroxyl group, an alkoxy group having 1 to 6 carbon atoms, an amino group having 0 to 6 carbon atoms, an alkylthio group having 1 to 5 carbon atoms, or an arylthio group having 6 to 10 carbon atoms. Since these are highly stable substituents, it is possible to prevent component A6 from changing into other compounds during storage. In addition, when having these substituents, one molecule of component A6 can absorb a sufficient amount of ultraviolet light. 1f , R 2f and R 3f More preferred is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or an aryl group having 6 to 12 carbon atoms, further preferred is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or an aryl group having 6 to 12 carbon atoms, and at least one of them is an alkyl group having 1 to 5 carbon atoms or an aryl group having 6 to 12 carbon atoms, particularly preferred is a hydrogen atom, a methyl group, an ethyl group, n-propyl or isopropyl group, or a phenyl group, and at least one of them is a methyl group, an ethyl group, n-propyl or isopropyl group, or a phenyl group, and even more preferred is a hydrogen atom, a methyl group, an ethyl group, isopropyl group, or a phenyl group, and at least one of them is a methyl group, an ethyl group, isopropyl group, or a phenyl group.

[0612] In addition, R 4f Preferred are alkyl groups having 1 to 10 carbon atoms, alkenyl groups having 2 to 10 carbon atoms, aryl groups having 6 to 12 carbon atoms, hydroxyl groups, alkoxy groups having 1 to 6 carbon atoms, amino groups having 0 to 6 carbon atoms, monovalent groups containing carbonyl groups having 1 to 6 carbon atoms, alkylthio groups having 1 to 5 carbon atoms, or arylthio groups having 6 to 10 carbon atoms. Since these are highly stable substituents, they can prevent component A6 from changing into other compounds during storage. 4f More preferably, it is an alkyl group having 1 to 5 carbon atoms, a hydroxyl group, an alkoxy group having 1 to 6 carbon atoms, or an amino group having 0 to 6 carbon atoms, and particularly preferably, it is a methyl group, an ethyl group, an n-propyl group or an isopropyl group, a hydroxyl group, a methoxy group, or an amino group, and most preferably, it is a methyl group, a hydroxyl group, a methoxy group, or an amino group. 4f In the case of this structure, the quality stability of the composition containing methacrylic acid during storage can be improved.

[0613] The alkyl group is a chain (straight or branched) alkyl group or a cyclic alkyl group. Preferably, it is an alkyl group having 1 to 20 carbon atoms, more preferably an alkyl group having 1 to 10 carbon atoms, and further preferably an alkyl group having 1 to 5 carbon atoms. As chain alkyl groups, for example, preferably, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, hexyl, octyl, decyl, hydroxymethyl, 1-hydroxyethyl, 2-hydroxyethyl, etc., methyl, ethyl, n-propyl, isopropyl. In addition, as cyclic alkyl groups, for example, cyclopentyl, cyclohexyl, cyclooctyl, etc. can be mentioned.

[0614] The alkenyl group is a chain (straight or branched) alkenyl group or a cyclic alkenyl group. Preferably, the alkenyl group has 2 to 20 carbon atoms, more preferably, the alkenyl group has 2 to 10 carbon atoms, and further preferably, the alkenyl group has 2 to 5 carbon atoms. Examples of chain alkenyl groups include vinyl, 1-propenyl, isopropenyl, 2-butenyl, 1,3-butadienyl, 2-pentenyl, and 2-hexenyl. In addition, examples of cyclic alkenyl groups include cyclopentenyl and cyclohexenyl.

[0615] The aryl group is preferably an aryl group having 1 to 20 carbon atoms, and more preferably an aryl group having 1 to 12 carbon atoms. The aryl group includes a heteroaryl group containing oxygen, nitrogen, sulfur, and the like. Examples of the aryl group include phenyl, mesityl, naphthyl, 2-methylphenyl, 3-methylphenyl, 4-methylphenyl, 2,3-dimethylphenyl, 2,4-dimethylphenyl, 2,5-dimethylphenyl, 2,6-dimethylphenyl, 2-ethylphenyl, isothiophenyl, 2-thiophenyl, 2-ethylphenyl, 2-isothio ... Azolyl, isothiazolyl, imidazolyl, oxazolyl, thiazolyl, thiadiazolyl, thienyl, triazolyl, tetrazolyl, pyridyl, pyrazinyl, pyrimidinyl, pyridazinyl, pyrazolyl, pyrrolyl, furanyl, furazanyl, isoquinolyl, isoindolyl, indolyl, quinolyl, pyridothiazolyl, benzimidazolyl, benzo oxazolyl, benzothiazolyl, benzotriazolyl, benzofuranyl, imidazopyridinyl, triazolopyridinyl, purinyl.

[0616] The alkoxy group is preferably an alkoxy group having 1 to 20 carbon atoms, more preferably an alkoxy group having 1 to 10 carbon atoms, and further preferably an alkoxy group having 1 to 6 carbon atoms. Examples of the alkoxy group include methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, sec-butoxy, tert-butoxy, n-pentyloxy, isopentyloxy, and phenoxy.

[0617] Amino groups include amino groups with no substituent on the nitrogen atom (-NH 2 ) (carbon number 0), and an amino group in which a part or all of the hydrogen atoms bonded to the nitrogen atom are substituted with carbon atoms. The number of carbon atoms of the amino group in which a part or all of the hydrogen atoms bonded to the nitrogen atom are substituted with carbon atoms is preferably 1 to 20, more preferably 1 to 10, and further preferably 1 to 6. Examples of the amino group include an unsubstituted amino group (—NH 2 ), methylamino, ethylamino, propylamino, butylamino, dimethylamino, diethylamino, aniline, toluidine, anisidine, diphenylamino, N-methyl-N-phenylamino, etc.

[0618] Examples of the monovalent group containing a carbonyl group include a formyl group, an acyl group, a carboxyl group, an amide group, an alkoxycarbonyl group, a thiocarboxyl group, and a thioester group. A monovalent group containing a carbonyl group having 1 to 6 carbon atoms is preferred.

[0619] The acyl group is a substituent formed by connecting a carbonyl group to an alkyl group, an alkenyl group, or an aryl group. The total number of carbon atoms (1) derived from the carbonyl group and the number of carbon atoms derived from the alkyl group, the alkenyl group, or the aryl group is preferably 2 to 20, more preferably 2 to 10, and even more preferably 2 to 6. Examples of the acyl group include acetyl, propionyl, butyryl, vinylcarbonyl, and benzoyl.

[0620] The amide group includes an amide group with no substituent on the nitrogen atom (-CONH 2 ), and an amide group in which a part or all of the hydrogen atoms bonded to the nitrogen atom are substituted with carbon atoms. The number of carbon atoms in the amide group is preferably 1 to 20, more preferably 1 to 10, and even more preferably 1 to 5, based on the total number of carbon atoms from the carbonyl group (1) and the number of carbon atoms substituted on the nitrogen atom. Examples of the amide group include an unsubstituted amide group, an N-methylamide group, an N-ethylamide group, an N-phenylamide group, an N,N-dimethylamide group, and an N-methyl-N-phenylamide group.

[0621] The alkoxycarbonyl group is a substituent formed by connecting a carbonyl group to an alkoxy group, and is also called an ester group. The total number of carbon atoms (1) derived from the carbonyl group and the number of carbon atoms derived from the alkoxy group is preferably 2 to 20, more preferably 2 to 10, and further preferably 2 to 6. Examples of the alkoxycarbonyl group include methoxycarbonyl, ethoxycarbonyl, butoxycarbonyl, and phenoxycarbonyl.

[0622] The thioester group is a substituent formed by connecting a carbonyl group to an alkylthio group or an arylthio group. The total number of carbon atoms (1) derived from the carbonyl group and the number of carbon atoms derived from the alkylthio group or the arylthio group is preferably 2 to 20, more preferably 2 to 10, and further preferably 2 to 6. Examples of the thioester group include methylthiocarbonyl, ethylthiocarbonyl, butylthiocarbonyl, and phenylthiocarbonyl.

[0623] In addition, the monovalent group containing a carbonyl group may be a substituent in which one or more hydrogen atoms of an alkyl group are replaced by a carbonyl group. Examples of such a substituent include 2-acetoxyethyl, 2-acetylethyl, and 2-(acetoacetoxy)ethyl.

[0624] The alkylthio group is preferably an alkylthio group having 1 to 20 carbon atoms, more preferably an alkylthio group having 1 to 10 carbon atoms, and further preferably an alkylthio group having 1 to 5 carbon atoms. Examples of the alkylthio group include methylthio, ethylthio, propylthio, and isopropylthio.

[0625] The arylthio group is preferably an arylthio group having 1 to 20 carbon atoms, more preferably an arylthio group having 3 to 10 carbon atoms, and further preferably an arylthio group having 6 to 10 carbon atoms. Examples of the arylthio group include a phenylthio group and a tolylthio group.

[0626] Among the compounds satisfying the above conditions, from the viewpoint of quality stability of the methacrylic acid-containing composition during storage, component A6 is preferably crotonic acid, 2-methyl crotonic acid, 3,3-dimethylacrylic acid, 2-methylene-3-butenoic acid, 2-pentenoic acid, 2-methyl-2-pentenoic acid, methyl methacrylate, methyl acrylate, 3-methyl-3-butene-2-one (isopropenyl methyl ketone), N-propyl methacrylamide, cinnamic acid, 3-methoxyacrylic acid, cis-crotonic acid, 2-ethylacrylic acid, 2-methylenepentanoic acid, 4-methyl-2-pentenoic acid, 2,4-pentadienoic acid, 2-methyl-2,4-pentadienoic acid, 2-hexenoic acid, 2-methyl-2 2-Hexenoic acid, 2-methylenehexanoic acid, 2-heptenoic acid, 2,4-heptadienoic acid, 2-octenoic acid, 2,4-octadienoic acid, 2,6-dimethyl-2-heptenoic acid, 6-methyl-2-methyleneheptanoic acid, 2,6-dimethyl-2,4-heptadienoic acid, 6-methyl-2-methylene-3-heptenoic acid, 2,5-dimethyl-2,4-hexadienedioic acid, ethyl methacrylate, isobutyl methacrylate, butyl methacrylate, propyl methacrylate, isopentyl methacrylate, cyclohexyl methacrylate, isobornyl methacrylate, hexyl methacrylate, propyl acrylate, butyl acrylate, methyl crotonate, cis-methyl crotonate, methyl 3,3-dimethacrylate, 2-ethylhexanoic acid, methyl acrylate, methyl 2-methylene-3-butenoate, methyl 2-pentenoate, methyl 2,4-pentadienoate, dimethyl fumarate, trans-3-hexen-2-one, methyl vinyl ketone, acrolein, crotonaldehyde, cis-crotonaldehyde, 2-methylene-3-butyraldehyde, 3,3-dimethylacrolein, 2-ethylacrolein, 2,4-pentadienal, 2-pentenal, 2-methyl-2,4-pentadienal, 4-methyl-2-pentenal, 2-methyl-2-pentenal, 2-methylenepentanal, 2-hexanal, 2-methyl-2-hexenal, 2-methylenehexanal, 2-heptanal, 2,4-heptadienal, 2-octanal, 2,4-octadienal, 2,6-dimethyl-2-heptadienal More preferably, it is crotonic acid, 2-methyl crotonic acid, 3,3-dimethylacrylic acid, 2-methylene-3-butenoic acid, 2-pentenoic acid, 2-methyl-2-pentenoic acid, methyl methacrylate, methyl acrylate, 3-methyl-3-butene-2-one (isopropenyl methyl ketone), N-propyl methacrylamide, cinnamic acid, or 3-methoxyacrylic acid, and more preferably, it is crotonic acid, 2-methyl crotonic acid, 3,3-dimethylacrylic acid, 2-methylene-3-butenoic acid, 2-pentenoic acid, 2-methyl-2-pentenoic acid, methyl methacrylate, methyl acrylate, 3-methyl-3-butene-2-one (isopropenyl methyl ketone), N-propyl methacrylamide, cinnamic acid, or 3-methoxyacrylic acid, and more preferably, it is crotonic acid, 2-methyl crotonic acid, 3,3-dimethylacrylic acid, 2-methylene-3-butenoic acid, 2-pentenoic acid, 2-methyl-2-pentenoic acid, methyl methacrylate, methyl acrylate, 3-methyl-3-butene-2-one (isopropenyl methyl ketone), N-propyl methacrylamide, cinnamic acid, or 3-methoxyacrylic acid.3-dimethylacrylic acid, 2-methylene-3-butenoic acid, 2-pentenoic acid, 2-methyl-2-pentenoic acid, methyl acrylate, 3-methyl-3-butene-2-one (isopropenyl methyl ketone), N-propyl methacrylamide, methacrylamide, cinnamic acid, particularly preferably crotonic acid, 2-methyl crotonic acid, 3,3-dimethylacrylic acid, 2-pentenoic acid, 2-methyl-2-pentenoic acid, methyl acrylate, isopropenyl methyl ketone, methacrylamide, cinnamic acid.

[0627] Component A6 may be used in one kind or in two or more kinds.

[0628] (ingredient B)

[0629] The methacrylic acid-containing composition of the sixth embodiment contains a polymerization inhibitor (component B). In the present specification, a polymerization inhibitor refers to a compound having the function of inhibiting the polymerization reaction of methacrylic acid. As the polymerization inhibitor, for example, phenolic compounds, quinone compounds, nitrobenzene compounds, N-oxyl radical compounds, amine compounds, phosphorus-containing compounds, sulfur-containing compounds, iron-containing compounds, copper-containing compounds and manganese-containing compounds can be cited. By containing component B, the polymerization reaction of methacrylic acid based on the free radical polymerization mechanism during the storage of methacrylic acid can be inhibited. In addition, component B can capture the above-mentioned hydroxyl radicals generated during the storage of methacrylic acid. That is, when the methacrylic acid-containing composition contains component B in addition to component A6, the amount of hydroxyl radicals can be reduced by the following two different mechanisms, that is, the generation of hydroxyl radicals can be inhibited by component A6, and the generated hydroxyl radicals can be removed by component B. Therefore, it is believed that the reduction of component B can be efficiently inhibited.

[0630] Examples of the polymerization inhibitor as a phenolic compound include alkylphenols, hydroxyphenols, aminophenols, nitrophenols, nitrosophenols, alkoxyphenols, and tocopherol.

[0631] Examples of the alkylphenol include o-cresol, m-cresol, p-cresol, 2-tert-butyl-4-methylphenol, 2,4-dimethyl-6-tert-butylphenol, 2,6-di-tert-butyl-4-methylphenol, 2-tert-butylphenol, 4-tert-butylphenol, 2,4-di-tert-butylphenol, 2-methyl-4-tert-butylphenol, 4-tert-butyl-2,6-dimethylphenol, 2,2′-methylenebis(4-ethyl-6-tert-butylphenol), 4,4′-thiobis(3-methyl-6-tert-butylphenol), and 3,5-di-tert-butyl-4-hydroxytoluene.

[0632] Examples of the hydroxyphenol include hydroquinone, 2-methylhydroquinone, 2-tert-butylhydroquinone, 2,5-di-tert-butylhydroquinone, 2,6-di-tert-butylhydroquinone, 2,5-di-tert-amylhydroquinone, 2-tert-butylmethoxyhydroquinone, 2,3,5-trimethylhydroquinone, 2,5-dichlorohydroquinone, 1,2-dihydroxybenzene, 2-acetylhydroquinone, 4-methylcatechol, 4-tert-butylcatechol, 2-methylresorcinol, 4-methylresorcinol, and 2,3-dihydroxyacetophenone.

[0633] Examples of the aminophenol include o-aminophenol, m-aminophenol, p-aminophenol, 2-(N,N-dimethylamino)phenol, and 4-(ethylamino)phenol.

[0634] Examples of the nitrophenol include o-nitrophenol, m-nitrophenol, p-nitrophenol, and 2,4-dinitrophenol.

[0635] Examples of the nitrosophenol include o-nitrosophenol, m-nitrosophenol, p-nitrosophenol, and α-nitroso-β-naphthol.

[0636] Examples of the alkoxyphenol include 2-methoxyphenol, 2-ethoxyphenol, 2-isopropoxyphenol, 2-tert-butoxyphenol, 4-methoxyphenol, 4-ethoxyphenol, 4-propoxyphenol, 4-butoxyphenol, 4-tert-butoxyphenol, 4-heptyloxyphenol, hydroquinone monobenzyl ether, tert-butyl-4-methoxyphenol, di-tert-butyl-4-methoxyphenol, pyrogallol-1,2-dimethyl ether, and hydroquinone monobenzoate.

[0637] Examples of the tocopherol include α-tocopherol and 2,3-dihydro-2,2-dimethyl-7-hydroxybenzofuran.

[0638] Examples of the polymerization inhibitor as a quinone compound include p-benzoquinone, chloro-p-benzoquinone, 2,5-dichloro-p-benzoquinone, 2,6-dichloro-p-benzoquinone, tetrachloro-p-benzoquinone, tetrabromo-p-benzoquinone, 2,3-dimethyl-p-benzoquinone, 2,5-dimethyl-p-benzoquinone, methoxy-p-benzoquinone, and methyl-p-benzoquinone.

[0639] Examples of the polymerization inhibitor as a nitrobenzene compound include nitrobenzene, o-dinitrobenzene, m-dinitrobenzene, p-dinitrobenzene, 2,4-dinitrobenzene, dinitrodurene, and 2,2-diphenyl-1-picrylhydrazyl.

[0640] Examples of the polymerization inhibitor as an N-oxyl radical compound include 4-hydroxy-2,2,6,6-tetramethyl-piperidin-N-oxyl radical, 4-oxo-2,2,6,6-tetramethyl-piperidin-N-oxyl radical, 4-acetoxy-2,2,6,6-tetramethyl-piperidin-N-oxyl radical, 2,2,6,6-tetramethyl-piperidin-N-oxyl radical, piperidine-1-oxyl radical, 4-(dimethylamino)-2,2,6,6-tetramethyl-piperidin-N-oxyl radical, 4-amino-2,2,6,6-tetramethyl-piperidin-N-oxyl radical, 4-vinyloxy-2,2,6,6-tetramethyl-piperidin-N-oxyl radical, 4-benzoyloxy-2,2,6,6-tetramethyl-piperidin-N-oxyl radical, -N-oxyl free radical, 2,2,5,5-tetramethyl-piperidinyl-N-oxyl free radical, 3-amino-2,2,5,5-tetramethyl-piperidinyl-N-oxyl free radical, 4,4',4"-tris(2,2,6,6-tetramethyl-piperidinyl-N-oxyl free radical)phosphite, 3-oxo-2,2,5,5-tetramethylpyrrolidine-N-oxyl free radical, pyrrolidine-1-oxyl free radical, 2,2,5,5-tetramethyl-1-oxa-3-azacyclopentyl-3-oxyl free radical, 2,2,5,5-tetramethyl-3-pyrrolinyl-1-oxyl-3-carboxylic acid, 2,2,3,3,5,5,6,6-octamethyl-1,4-diazacyclohexyl-1,4-dioxyl free radical, di-tert-butylnitroxide, di-tert-amylnitroxide, etc.

[0641] Examples of the polymerization inhibitor as an amine compound include N,N-diphenylamine, alkylated diphenylamine, 4,4'-dicumyldiphenylamine, 4,4'-dioctyldiphenylamine, 4-aminodiphenylamine, p-nitrosodiphenylamine, N-nitrosodinaphthylamine, N-nitrosodiphenylamine, N-nitrosophenylnaphthylamine, N-nitrosophenylhydroxylamine, N,N'-dialkyl-p-phenylenediamine (the alkyl groups may be the same or different, each independently having 1 to 4 carbon atoms, and may be linear or branched), N,N'-diphenyl-p-phenylenediamine, N-phenyl-N'-isopropyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-1,4-phenylenediamine, N,N'-di-2-naphthylamine, 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline, 2,2,4-trimethyl-1,2-dihydroquinoline polymer, butyral-α-naphthylamine, N-phenyl-β-naphthylamine, 4-hydroxy-2,2,6,6-tetramethylpiperidine, 4-benzoyloxy-2,2,6,6-tetramethylpiperidine, 1,4-dihydroxy-2,2,6,6-tetramethylpiperidine, 1-hydroxy-4-benzoyloxy-2,2,6,6-tetramethylpiperidine, etc.

[0642] Examples of the polymerization inhibitor as a phosphorus-containing compound include triphenylphosphine, triphenyl phosphite, triethyl phosphite, tris(isodecyl) phosphite, tris(tridecyl) phosphite, phenyl diisooctyl phosphite, phenyl diisodecyl phosphite, phenyl di(tridecyl) phosphite, diphenyl isooctyl phosphite, diphenyl isodecyl phosphite, diphenyl tridecyl phosphite, [1,1-diphenyl-4,4'-diyl-bis[tetrakis-2,4-bis(1,1-dimethylethyl)phenyl]]phosphonate, tris(nonylphenyl) phosphite, 4,4'-isopropylidene diphenol alkyl phosphite, tris(2,4-di-tert-butylphenyl) phosphite, and terphenyl phosphite. Ester, distearyl pentaerythritol diphosphite, di(2,4-di-tert-butylphenyl) pentaerythritol diphosphite, di(nonylphenyl) pentaerythritol diphosphite, phenyl bisphenol A pentaerythritol diphosphite, tetra(tridecyl)-4,4'-butylidene bis(3-methyl-6-tert-butylphenol) diphosphite, hexa(tridecyl)-1,1,3-tri(2-methyl-4-hydroxy-5-tert-butylphenyl) butane triphosphite, 3,5-di-tert-butyl-4-hydroxybenzyl phosphate diethyl ester, bis(4-tert-butylphenyl) phosphate sodium salt, 2,2'-methylene-bis(4,6-di-tert-butylphenyl) phosphate sodium salt, 1,3-bis(diphenoxyphosphoryloxy)benzene, etc.

[0643] Examples of the polymerization inhibitor as a sulfur-containing compound include diphenyl sulfide, phenothiazine, 3-oxophenothiazine, 5-oxophenothiazine, phenothiazine dimer, 1,4-dimercaptobenzene, 1,2-dimercaptobenzene, 2-mercaptophenol, 4-mercaptophenol, 2-(methylthio)phenol, and 3,7-bis(dimethylamino)phenothiazine. Chloride, sulfur (elemental), etc.

[0644] Examples of the polymerization inhibitor as an iron-containing compound include iron (III) chloride and the like.

[0645] Examples of the polymerization inhibitor as a copper compound include copper dimethyldithiocarbamate, copper diethyldithiocarbamate, copper dibutyldithiocarbamate, copper salicylate, copper acetate, copper thiocyanate, copper nitrate, copper chloride, copper carbonate, copper hydroxide, copper acrylate, copper methacrylate, and the like.

[0646] Examples of the polymerization inhibitor as a manganese-containing compound include manganese dialkyldithiocarbamate (the alkyl group is any of methyl, ethyl, propyl and butyl, and may be the same or different), manganese diphenyldithiocarbamate, manganese formate, manganese acetate, manganese octoate, manganese naphthenate, manganese permanganate, and manganese salt of ethylenediaminetetraacetic acid.

[0647] Among the above, from the viewpoint of quality stability of the composition containing methacrylic acid during storage, as component B, at least one polymerization inhibitor selected from phenolic compounds, N-oxyl radical compounds, amine compounds, phosphorus-containing compounds and sulfur-containing compounds is preferred, and for example, at least one polymerization inhibitor selected from hydroquinone, 4-methoxyphenol, 2,4-dimethyl-6-tert-butylphenol, 2,6-di-tert-butyl-4-methylphenol, 4-hydroxy-2,2,6,6-tetramethylpiperidinyl-N-oxyl radical, N,N-diphenylamine, N-nitrosodiphenylamine, triphenyl phosphite and phenothiazine is preferred. Component B is more preferably a phenolic compound, and for example, at least one polymerization inhibitor selected from hydroquinone, 4-methoxyphenol, 2,4-dimethyl-6-tert-butylphenol and 2,6-di-tert-butyl-4-methylphenol is more preferred. Component B is more preferably at least one polymerization inhibitor selected from, for example, hydroquinone, 4-methoxyphenol, and 2,6-di-tert-butyl-4-methylphenol. Component B is particularly preferably at least one polymerization inhibitor selected from, for example, hydroquinone and 4-methoxyphenol.

[0648] Component B may be one kind or two or more kinds.

[0649] When the composition containing methacrylic acid contains a compound corresponding to both component A6 and component B, the compound is regarded as component B. That is, the composition containing methacrylic acid needs to contain component A6 different from the compound. When two or more compounds corresponding to both component A6 and component B are contained, the compound with the highest molar concentration in the composition containing methacrylic acid is regarded as component B, and the other compounds are regarded as component A6.

[0650] (Concentration of Component A6 and Component B)

[0651] The concentration of component A6 is M A6 (μmol / L), the concentration of component B is M B (μmol / L), from the viewpoint of the efficiency of inhibiting the consumption of the polymerization inhibitor, M B / M A6 It is preferably 0.0005 to 500, more preferably 0.001 to 450, further preferably 0.005 to 400, further preferably 0.005 to 350.

[0652] M A6 It is preferably 1 to 85000 μmol / L. A6 When the concentration of M is 1 μmol / L or more, the effect of inhibiting the decomposition of the polymerization inhibitor can be fully obtained. A6 When the concentration is 85000 μmol / L or less, the amount of impurities when producing a methacrylic acid polymer by polymerizing the methacrylic acid-containing composition of the sixth embodiment can be reduced, thereby preventing adverse effects on the physical properties of the polymer. A6 The lower limit of M is more preferably 10 μmol / L or more, further preferably 30 μmol / L or more, more preferably 50 μmol / L or more, particularly preferably 70 μmol / L or more, even more preferably 80 μmol / L or more, and most preferably 85 μmol / L or more. A6 The upper limit is more preferably 65000 μmol / L or less, further preferably 45000 μmol / L or less, particularly preferably 25000 μmol / L or less, even more preferably 15000 μmol / L or less, and most preferably 5000 μmol / L or less.

[0653] M B It is preferably 1 to 50000 μmol / L. B When the concentration of M is 1 μmol / L or more, the effect of inhibiting the decomposition of the polymerization inhibitor can be fully obtained. BWhen the concentration is 50000 μmol / L or less, the amount of impurities when producing a methacrylic acid polymer by polymerizing the methacrylic acid-containing composition of the sixth embodiment can be reduced, thereby preventing adverse effects on the physical properties of the polymer. B The lower limit of M is more preferably 10 μmol / L or more, further preferably 100 μmol / L or more, particularly preferably 1000 μmol / L or more, and even more preferably 2000 μmol / L or more. B The upper limit is more preferably 40000 μmol / L or less, further preferably 30000 μmol / L or less, and particularly preferably 25000 μmol / L or less.

[0654] (Methacrylic acid concentration)

[0655] The methacrylic acid concentration of the methacrylic acid-containing composition of the sixth embodiment is 98.00 to 99.99% by mass. When the methacrylic acid concentration is 98.00% by mass or more, the amount of impurities when the methacrylic acid polymer is produced by polymerization of the methacrylic acid-containing composition can be reduced, and the physical properties of the polymer can be prevented from being adversely affected. In addition, by making the methacrylic acid concentration 99.99% by mass or less, the purification cost can be reduced. The lower limit of the methacrylic acid concentration is more preferably 98.50% or more, further preferably 99.00% or more, particularly preferably 99.50% or more, and most preferably 99.80% or more by mass.

[0656] (Ingredient C)

[0657] The methacrylic acid-containing composition of the sixth embodiment may further contain component C as another compound as long as the methacrylic acid concentration satisfies 98.00 to 99.99% by mass. Examples of component C include impurities generated in the production process of methacrylic acid. For example, methacrylic acid may contain diacetyl as an impurity, and from the viewpoint of reducing coloration of the methacrylic acid-containing composition, the concentration of diacetyl is preferably 55 μmol / L or less, more preferably 20 μmol / L or less, further preferably 10 μmol / L or less, and particularly preferably 1 μmol / L or less.

[0658] (Analysis of Compositions Containing Methacrylic Acid)

[0659] The fact that the composition containing methacrylic acid contains component A6, component B, component C, and water can be confirmed by, for example, GC-MS measurement. In the GC-MS spectrum of the composition containing methacrylic acid, if there is a peak at the same retention time as the standard of component A6, and the m / z value detected in the mass spectrum of the peak is consistent with the accurate mass of component A6, it can be determined that the composition containing methacrylic acid contains component A6. In the case where a standard of component A6 is not available, when the pattern of the mass spectrum of the peak appearing in the GC-MS spectrum of the composition containing methacrylic acid is consistent with the pattern of the mass spectrum of component A6 included in the mass spectrum database, it can be determined that the peak is the component A6 peak. That is, it can be determined that the composition containing methacrylic acid contains component A6. Examples of mass spectrum databases include NIST20, NIST17, NIST14, and NIST14s. In addition, when the volatility is low and cannot be detected by GC-MS measurement, LC-MS can be used for detection. Component B, component C, and water can also be confirmed by the same method as component A1.

[0660] In addition, the concentration of methacrylic acid can be calculated by, for example, performing GC-FID measurement on a composition containing methacrylic acid, quantifying it using the area percentage method, and correcting it using the amount of water quantified by a Karl Fischer titrator. The concentration of component A6 can be quantified by, for example, performing GC measurement on a composition containing methacrylic acid and using an internal standard method. In the case where a standard product of component A6 is not available and quantification cannot be performed using the internal standard method, an organic compound with a known concentration can be subjected to GC-FID measurement under the same conditions as the composition containing methacrylic acid, and the concentration of component A6 can be calculated using the following formula.

[0661]

[0662] Here, N is the number of carbon atoms in one molecule of an organic compound with a known concentration. A6 is the number of carbon atoms in one molecule of component A6, S A6 is the peak area of ​​component A6, S is the peak area of ​​the organic compound of known concentration, and M is the concentration (μmol / L) of the organic compound of known concentration.

[0663] When volatility is low and quantification by GC is not possible, quantification can be performed by chromatography such as LC.

[0664] The concentrations of Component B and Component C can also be calculated by the same method as that of Component A6 described above.

[0665] In addition, the presence of water in the composition containing methacrylic acid and the concentration of water can be confirmed by Karl Fischer method.

[0666] [Method for producing a composition containing methacrylic acid]

[0667] As a sixth method for producing a composition containing methacrylic acid, there can be mentioned a method of adding component A6 and component B to methacrylic acid. Methacrylic acid can use a commercial product, or methacrylic acid produced by a known method such as the acetone cyanohydrin (ACH) method and the C4 direct oxidation method. Component A6 and component B can use a commercial product, or a compound synthesized by a known method. In the case of using a substance produced by a known method such as the acetone cyanohydrin (ACH) method and the C4 direct oxidation method for methacrylic acid, component A6 or component B can be added in the middle of the raw material or the production process to produce a composition containing methacrylic acid. In addition, in the case where component A6 or component B is generated as a by-product in the methacrylic acid production process, a composition containing methacrylic acid can be produced by leaving a portion of the generated component A6 or component B.

[0668] [Evaluation method of storage stability and thermal stability]

[0669] The methacrylic acid-containing composition of the sixth embodiment has high quality stability during storage. As an evaluation method for the quality stability of the methacrylic acid-containing composition during storage, for example, a method of actually storing the methacrylic acid-containing composition for a long time and confirming the reduction in the amount of the polymerization inhibitor can be cited. In addition, from the perspective of simplicity of operation, a method of heating the methacrylic acid-containing composition for a short time and confirming the reduction in the amount of the polymerization inhibitor can be used. When heating for a short time, the heating temperature is preferably 50 to 100°C, and the heating time is preferably 1 to 24 hours. In the present invention, the quality stability of the methacrylic acid-containing composition during storage is evaluated based on the reduction in the amount of the polymerization inhibitor when the methacrylic acid-containing composition is stored at 25°C for 21 days.

[0670] [Method for producing methacrylate]

[0671] The method for producing a methacrylic acid ester of the sixth aspect includes a step of esterifying the methacrylic acid-containing composition of the sixth aspect.

[0672] The alcohol to be reacted with the composition containing methacrylic acid is not particularly limited, and examples thereof include methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, and the like. Examples of the methacrylic acid esters obtained include methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, butyl methacrylate, and isobutyl methacrylate. The esterification reaction may be carried out in the presence of an acidic catalyst such as a sulfonic acid type cation exchange resin. The temperature in the esterification reaction is preferably 50 to 200°C.

[0673] The pressure during the esterification reaction, the position of the catalyst in the reactor, the ratio of the catalyst in the reactor, and the like are not particularly limited, and commonly used methods can be applied.

[0674] [Method for producing methacrylic acid polymer according to the sixth aspect]

[0675] The method for producing a methacrylic acid polymer of the sixth embodiment includes a step of polymerizing a polymerizable composition containing the methacrylic acid-containing composition of the sixth embodiment.

[0676] The polymerizable composition may contain a monomer copolymerizable with methacrylic acid and other additives as necessary.

[0677] Examples of the monomer copolymerizable with methacrylic acid include the following monomers.

[0678] Methacrylates such as methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, 2-ethylhexyl methacrylate, phenyl methacrylate, or benzyl methacrylate;

[0679] Acrylates such as methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, tert-butyl acrylate, or 2-ethylhexyl acrylate;

[0680] Unsaturated carboxylic acids such as acrylic acid, maleic acid, or itaconic acid;

[0681] Unsaturated carboxylic anhydrides such as maleic anhydride or itaconic anhydride;

[0682] Maleimides such as N-phenylmaleimide or N-cyclohexylmaleimide;

[0683] A vinyl monomer containing a hydroxyl group, such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, or 2-hydroxypropyl methacrylate;

[0684] Vinyl esters such as vinyl acetate or vinyl benzoate;

[0685] Vinyl chloride, vinylidene chloride and their derivatives;

[0686] Nitrogen-containing vinyl monomers such as methacrylamide or acrylonitrile;

[0687] Monomers containing epoxy groups such as glycidyl acrylate or glycidyl methacrylate;

[0688] Aromatic vinyl monomers such as styrene or α-methylstyrene;

[0689] Alkanediol di(meth)acrylates such as ethylene glycol di(meth)acrylate, 1,2-propylene glycol di(meth)acrylate, 1,3-butylene glycol di(meth)acrylate, or 1,6-hexanediol di(meth)acrylate;

[0690] Polyoxyalkylene glycol di(meth)acrylates such as diethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, triethylene glycol (meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, or neopentyl glycol di(meth)acrylate;

[0691] Vinyl monomers having two or more ethylenically unsaturated bonds in the molecule, such as divinylbenzene;

[0692] An unsaturated polyester prepolymer obtained from at least one polycarboxylic acid including an ethylenically unsaturated polycarboxylic acid and at least one diol;

[0693] A vinyl ester prepolymer obtained by modifying the epoxy group terminal with acrylic acid.

[0694] Among the above, the monomer copolymerizable with methacrylic acid is preferably at least one selected from methacrylic acid esters and acrylates. The monomer copolymerizable with methacrylic acid is more preferably methacrylic acid ester, and particularly preferably methyl methacrylate.

[0695] The monomer copolymerizable with methacrylic acid may be one or more. In addition, when component A6 is a monomer copolymerizable with methacrylic acid, component A6 may be used as a monomer copolymerizable with methacrylic acid, or a monomer copolymerizable with methacrylic acid different from component A6 may be used.

[0696] In the polymerizable composition, the upper limit of the content of the monomer copolymerizable with methacrylic acid is preferably 99.99 parts by mass or less relative to 100 parts by mass of the polymerizable composition. The lower limit of the content of the monomer copolymerizable with methacrylic acid is preferably 50 parts by mass or more, more preferably 60 parts by mass or more, further preferably 70 parts by mass or more, particularly preferably 80 parts by mass or more, and most preferably 90 parts by mass or more, relative to 100 parts by mass of the polymerizable composition. The upper limit of the content of the monomer copolymerizable with methacrylic acid is more preferably 99.9 parts by mass or less, and further preferably 99 parts by mass or less, relative to 100 parts by mass of the polymerizable composition.

[0697] As other additives, polymerization initiators are preferred. In addition, the polymerizable composition may contain chain transfer agents, mold release agents, lubricants, plasticizers, antioxidants, antistatic agents, light stabilizers, ultraviolet absorbers, flame retardants, flame retardant aids, polymerization inhibitors, fillers, pigments, dyes, silane coupling agents, leveling agents, defoamers, fluorescent agents, etc. as needed. The other additives may be one or more.

[0698] Examples of the polymerization initiator include the following compounds.

[0699] Azo compounds such as 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), 2,2'-azobis(2-methylpropionitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2,4,4-trimethylpentane), 2,2'-azobis(2-methylpropane), 1,1-azobis(cyclohexanecarbonitrile), and 2,2'-azobisisobutyric acid dimethyl ester;

[0700] Benzoyl peroxide, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, 1,1-bis(tert-butylperoxy)cyclohexane, 1,1-bis(tert-butylperoxy)-3,5,5-trimethylcyclohexane, tert-butyl peroxy-2-ethylhexanoate, tert-butyl peroxyisobutyrate, tert-butyl peroxybenzoate, tert-hexyl peroxybenzoate, tert-butyl peroxyisopropyl monocarbonate, tert-butyl peroxy-3,5,5-trimethylhexanoate, tert-butyl peroxylaurate, tert-butyl peroxyacetate, tert-hexyl peroxyisopropyl monocarbonate, tert-ethyl peroxy Organic peroxides such as tert-hexyl hexanoate, tert-amyl peroxy-2-ethylhexanoate, 1,1,3,3-tetramethylbutyl peroxyethylhexanoate, 1,1,2-trimethylpropyl peroxy-2-ethylhexanoate, 1,1,3,3-tetramethylbutyl peroxyisopropyl monocarbonate, 1,1,2-trimethylpropyl peroxyisopropyl monocarbonate, 1,1,3,3-tetramethylbutyl peroxyisononanoate, 1,1,2-trimethylpropyl peroxy-isononanoate, di-tert-butyl peroxide, di-tert-hexyl peroxide, lauroyl peroxide, and dilauroyl peroxide;

[0701] Persulfate compounds such as potassium persulfate;

[0702] Redox polymerization initiator.

[0703] Among the above, the polymerization initiator is preferably at least one selected from azo compounds and organic peroxides from the viewpoint of storage stability and reactivity of methacrylic acid with a copolymerizable monomer.

[0704] The amount of the polymerization initiator used is preferably 0.0001 to 1 part by mass based on 100 parts by mass of the total of methacrylic acid and the monomer copolymerizable with methacrylic acid.

[0705] Examples of the polymerization method for the polymerizable composition include bulk polymerization, solution polymerization, emulsion polymerization, and suspension polymerization.

[0706] The polymerization temperature is preferably 125 to 210° C. This allows for an appropriate polymerization rate. More preferably, the lower limit of the polymerization temperature is 130° C. or higher and the upper limit is 180° C. or lower. The polymerization time is not particularly limited and may be, for example, 0.5 to 24 hours.

[0707] Example

[0708] Hereinafter, the embodiment will be described in more detail by way of examples and comparative examples, but the present invention is not limited to these examples. "%" and "ppm" in the examples and comparative examples mean "% by weight" and "ppm by weight" unless otherwise specified.

[0709] The water concentration contained in the methacrylic acid of the reagent was calculated by Karl Fischer method. The composition of the constituent components of the composition containing methacrylic acid before storage was calculated based on the amount of each raw material added. The amount of the polymerization inhibitor after storage was quantified using GC-FID using the absolute standard curve method. The measurement conditions of GC-FID are shown below.

[0710] Apparatus: GC-FID (product name: GC7890B, manufactured by Agilent)

[0711] [GC conditions]

[0712] Column (product name: Rtx-1701, manufactured by Restek, length: 30 m, inner diameter: 0.25 mm, membrane thickness: 1.00 μm)

[0713] Injection volume: 1.0 μL

[0714] Gasification chamber temperature: 260℃

[0715] Column oven temperature: maintained at 40°C for 10 minutes, increased from 40°C to 2400°C at 10°C / min and maintained at 240°C for 10 minutes.

[0716] Carrier gas: Helium

[0717] Injection mode: split (split ratio 50)

[0718] Control mode: Constant linear speed (39.723 cm / s)

[0719] Detector temperature: 260°C

[0720] Detector H2 flow rate: 30mL / min

[0721] Detector Air flow: 400mL / min

[0722] Tail blowing He flow rate: 25mL / min

[0723] The quantitative determination of the water concentration by the Karl Fischer method was performed using an automatic water content measuring device (product name: AQV-2200, manufactured by Hiranuma Industry Co., Ltd.).

[0724] (Example a1)

[0725] Using 2-isopropylhydroquinone as the component A1 reagent, 10.0081 g of methacrylic acid reagent (containing a water concentration of 366 ppm and a 4-methoxyphenol concentration of 306 ppm as the component B1) was added to 0.0192 g of the component A1 to prepare a methacrylic acid solution (A-a1 liquid). The concentration of the component A1 in the A-a1 liquid is shown in Table 1.

[0726] Next, 0.0526 g of the A-a1 liquid was added to 9.9585 g of methacrylic acid (water concentration 366 ppm, 4-methoxyphenol concentration as component B1 306 ppm) to prepare a composition containing methacrylic acid.

[0727] The obtained methacrylic acid-containing composition was stored at 25° C. for 21 days. Table 2 shows the reduction rate of the polymerization inhibitor (component B1) in the methacrylic acid-containing composition after the storage.

[0728] (Examples a2, a3, a5)

[0729] A-a solutions were prepared in the same manner as in Example a1 except that the compounds shown in Table 1 were used as Component A and the amounts of the reagent MAA and Component A were changed as shown in Table 1.

[0730] Next, MAA-containing compositions were prepared in the same manner as in Example a1 except that the amounts of reagent MAA and A-a solution were changed as shown in Table 2. Table 2 shows the reduction rate of the polymerization inhibitor (component B1) in the methacrylic acid-containing composition after storage.

[0731] (Example a4)

[0732] A-a4 liquid was prepared by the same method as in Example a1 except that 2-phenylisobutyric acid was used as the reagent for Component A.

[0733] Next, using hydroquinone as component B2, 0.4323 g of component B2 was added to 40.0050 g of methacrylic acid reagent (water concentration 366 ppm, 4-methoxyphenol concentration 306 ppm as component B1) to prepare a methacrylic acid solution (B-a4). The concentration of component B2 in this B-a4 solution is shown in Table 1.

[0734] Next, 0.0600 g of A-a4 liquid and 0.2507 g of B-a4 liquid were added to 9.7103 g of methacrylic acid (water concentration 366 ppm, 4-methoxyphenol concentration 306 ppm as component B1) to prepare a composition containing methacrylic acid. The concentrations of the components in the composition containing methacrylic acid are shown in Table 2. The reduction rate of the polymerization inhibitor (component B1) in the composition containing methacrylic acid after storage is shown in Table 2.

[0735] (Example a6)

[0736] A methacrylic acid-containing composition was prepared by using reagent 2-phenylisobutyric acid as component A1 and adding 0.0089 g of component A1 to 9.9955 g of reagent methacrylic acid (water concentration 366 ppm, 4-methoxyphenol concentration 306 ppm as component B1). The concentrations of the components in the methacrylic acid-containing composition are shown in Table 2.

[0737] (Examples a7, a8)

[0738] A-a solutions were prepared in the same manner as in Example a1 except that the compounds shown in Table 1 were used as Component A and the amounts of the reagent MAA and Component A were changed as shown in Table 1.

[0739] Each B-b solution was prepared in the same manner as in Example a4 except that the compound shown in Table 1 was used as Component B and the amounts of the reagent MAA and Component B were changed as shown in Table 1.

[0740] Next, MAA-containing compositions were prepared in the same manner as in Example a4 except that the amounts of reagent MAA, A-a solution, and B-b solution were changed as shown in Table 2. Table 2 shows the reduction rate of the polymerization inhibitor (component B1) in the methacrylic acid-containing composition after storage.

[0741] (Comparative Example a1)

[0742] Using the reagent 4-methoxyphenol as the component B1, 0.4016 g of 4-methoxyphenol was added to 40.0219 g of the reagent methacrylic acid (water concentration 366 ppm, 4-methoxyphenol concentration as the component B1 306 ppm) to prepare a mixture A-b1.

[0743] Next, 0.5000 g of the B-a1 liquid was added to 19.5000 g of methacrylic acid (water concentration: 366 ppm) as a reagent to prepare a composition containing methacrylic acid. Table 2 shows the concentrations of the components in the composition containing methacrylic acid.

[0744] The obtained methacrylic acid-containing composition was stored in the same manner as in Example a1. Table 2 shows the reduction rate of the polymerization inhibitor (component B1) in the methacrylic acid-containing composition after the storage.

[0745] (Comparative Example a2)

[0746] Methacrylic acid as a reagent (water concentration 366 ppm, 4-methoxyphenol concentration 306 ppm as component B1) was stored at 25° C. for 21 days. Table 2 shows the reduction rate of the polymerization inhibitor (component B1) in the methacrylic acid-containing composition after the storage.

[0747] (Comparative Example a3)

[0748] A solution A-a was prepared in the same manner as in Example a1 except that the compounds shown in Table 1 were used as component A and the amounts of reagent MAA and component A were changed as shown in Table 1.

[0749] A composition containing methacrylic acid was prepared by adding 0.0971 g of A-a liquid and 0.0565 g of pure water to 19.4088 g of methacrylic acid (water concentration 366 ppm, 4-methoxyphenol concentration 306 ppm). The concentrations of the components in the composition containing methacrylic acid are shown in Table 2. The reduction rate of the polymerization inhibitor (component B1) in the composition containing methacrylic acid after storage is shown in Table 2.

[0750]

[0751]

[0752] As shown in Table 1 and Table 2, in Examples a1 to a8, the reduction rate of the polymerization inhibitor (component B1) in the methacrylic acid composition after storage was suppressed. It can be said that the quality stability during storage is high.

[0753] (Examples b1-b9)

[0754] A C-a solution was prepared in the same manner as in Example a1 except that the compound shown in Table 3 was used as Component A21 and the amounts of the reagent MAA and Component A21 were changed as shown in Table 3.

[0755] Next, a composition containing MAA was prepared in the same manner as in Example a1 except that the amounts of reagent MAA and C-a solution were changed as shown in Table 4. The concentrations of the components in the composition containing methacrylic acid are shown in Table 4. The reduction rate of the polymerization inhibitor (component B1) in the composition containing methacrylic acid after storage at 25° C. for 21 days is shown in Table 4.

[0756] (Comparative Example b1)

[0757] A composition containing methacrylic acid was prepared by adding 0.4611 g of component A21 to 19.5520 g of methacrylic acid (water concentration 366 ppm, 4-methoxyphenol concentration 306 ppm as component B1) using reagent 2,3,5,6-tetramethylpyrazine as component A21. The concentration of each component in the composition containing methacrylic acid is shown in Table 4. The reduction rate of the polymerization inhibitor (component B1) in the composition containing methacrylic acid after storage at 25°C for 21 days is shown in Table 4.

[0758]

[0759]

[0760] As shown in Tables 3 and 4, in Examples b1 to b9, the decomposition of the polymerization inhibitor (component B1) in the methacrylic acid composition after storage was suppressed. It can be said that the quality stability during storage is high.

[0761] (Examples c1, c2, c3, c5)

[0762] C-a solutions were prepared in the same manner as in Example a1 except that the compounds shown in Table 5 were used as Component A3 and the amounts of the reagent MAA and Component A3 were changed as shown in Table 5.

[0763] Next, compositions containing MAA were prepared in the same manner as in Example a1 except that the amounts of reagent MAA and C-a solution were changed as shown in Table 6. The concentrations of the components in the compositions containing methacrylic acid are shown in Table 6. The reduction rate of the polymerization inhibitor (component B1) in the compositions containing methacrylic acid after storage at 25° C. for 21 days is shown in Table 6.

[0764] (Example c4)

[0765] A composition containing MAA was prepared by the same method as Example a4 except that tert-butylphenyl ether was used as the reagent for component A3. The concentrations of the components in the composition containing methacrylic acid are shown in Table 6. The reduction rate of the polymerization inhibitor (component B1) in the composition containing methacrylic acid after storage at 25° C. for 21 days is shown in Table 6.

[0766] (Example c6)

[0767] A composition containing MAA was prepared by the same method as in Example a6 except that tert-butylphenyl ether was used as the reagent for component A3. The concentrations of the components in the composition containing methacrylic acid are shown in Table 6. The reduction rate of the polymerization inhibitor (component B1) in the composition containing methacrylic acid after storage at 25° C. for 21 days is shown in Table 6.

[0768] (Examples c7, c8)

[0769] Except having used tert-butylphenyl ether as Component A3, C-a liquid was prepared in the same manner as in Example a1. Next, C-b liquid was prepared in the same manner as in Example a7.

[0770] The reagent MAA, C-a solution, and C-b solution were added in the amounts shown in Table 6 to prepare compositions containing methacrylic acid. The concentrations of the components in the compositions containing methacrylic acid are shown in Table 6. The reduction rate of the polymerization inhibitor (component B1) in the compositions containing methacrylic acid after storage at 25° C. for 21 days is shown in Table 6.

[0771] (Comparative Example c1)

[0772] A methacrylic acid-containing composition was prepared in the same manner as in Comparative Example b1 except that tert-butylphenyl ether was used as component A. The concentrations of the components in the methacrylic acid-containing composition are shown in Table 6. The reduction rate of the polymerization inhibitor (component B1) in the methacrylic acid-containing composition after storage at 25° C. for 21 days is shown in Table 6.

[0773] (Comparative Example c2)

[0774] A methacrylic acid-containing composition was prepared in the same manner as in Comparative Example a3 except that tert-butylphenyl ether was used as Component A3. The concentrations of the components in the methacrylic acid-containing composition are shown in Table 6. The reduction rate of the polymerization inhibitor (Component B1) in the methacrylic acid-containing composition after storage at 25° C. for 21 days is shown in Table 6.

[0775]

[0776]

[0777] As shown in Tables 5 and 6, in Examples c1 to c8, the decomposition of the polymerization inhibitor (component B1) in the methacrylic acid composition after storage was suppressed. It can be said that the quality stability during storage is high.

[0778] (Examples d1-d6)

[0779] The D-a liquids were prepared in the same manner as in Example a1 except that the compounds shown in Table 7 were used as Component A4 and the amounts of the reagent MAA and Component A4 were changed as shown in Table 7.

[0780] Next, compositions containing MAA were prepared in the same manner as in Example a1 except that the amounts of reagent MAA and D-a solution were changed as shown in Table 8. The concentrations of the components in the compositions containing methacrylic acid are shown in Table 8. The reduction rate of the polymerization inhibitor (component B1) in the compositions containing methacrylic acid after storage at 25° C. for 21 days is shown in Table 8.

[0781] (Example d7)

[0782] A methacrylic acid-containing composition was prepared in the same manner as in Example a4 except that methacrylonitrile was used as Component A4. The concentrations of the components in the methacrylic acid-containing composition are shown in Table 8. The reduction rate of the polymerization inhibitor (Component B1) in the methacrylic acid-containing composition after storage at 25° C. for 21 days is shown in Table 8.

[0783] (Example d8)

[0784] A D-a solution was prepared in the same manner as in Example a1 except that the compound shown in Table 7 was used as Component A4 and the amounts of the reagent MAA and Component A4 were changed as shown in Table 7.

[0785] Next, a composition containing MAA was prepared in the same manner as in Example a1 except that the amounts of reagent MAA and D-a solution were changed as shown in the table. The concentrations of the components in the composition containing methacrylic acid are shown in Table 8. The reduction rate of the polymerization inhibitor (component B1) in the composition containing methacrylic acid after storage at 25°C for 21 days is shown in Table 8.

[0786] (Example d9)

[0787] A methacrylic acid-containing composition was prepared in the same manner as in Example a6 except that methacrylonitrile was used as Component A4. The concentrations of the components in the methacrylic acid-containing composition are shown in Table 8. The reduction rate of the polymerization inhibitor (Component B1) in the methacrylic acid-containing composition after storage at 25° C. for 21 days is shown in Table 8.

[0788] (Examples d10, d11)

[0789] Each D-a liquid was prepared in the same manner as in Example a1 except that methacrylonitrile was used as Component A4. Next, each D-b liquid was prepared in the same manner as in Example a7.

[0790] The reagent MAA, D-a liquid, and D-b liquid were added in the amounts shown in Table 8 to prepare a composition containing methacrylic acid. The concentrations of the components in the composition containing methacrylic acid are shown in Table 8. The reduction rate of the polymerization inhibitor (component B1) in the composition containing methacrylic acid after storage at 25° C. for 21 days is shown in Table 8.

[0791] (Comparative Example d1)

[0792] A methacrylic acid-containing composition was prepared in the same manner as in Comparative Example b1, except that methacrylonitrile was used as Component B. Table 8 shows the concentration of each component in the methacrylic acid-containing composition.

[0793] The obtained methacrylic acid-containing composition was stored in the same manner as in Example d1. Table 8 shows the reduction rate of the polymerization inhibitor (component B1) in the methacrylic acid-containing composition after the storage.

[0794] (Comparative Example d2)

[0795] A methacrylic acid-containing composition was prepared in the same manner as in Comparative Example a1 except that methacrylonitrile was used as component B. The concentrations of the components in the methacrylic acid-containing composition are shown in Table 8. The reduction rate of the polymerization inhibitor (component B1) in the methacrylic acid-containing composition after storage at 25° C. for 21 days is shown in Table 8.

[0796]

[0797]

[0798] As shown in Tables 7 and 8, in Examples d1 to d11, the decomposition of the polymerization inhibitor (component B1) in the methacrylic acid composition after storage was suppressed. It can be said that the quality stability during storage is high.

[0799] (Examples e1-e9)

[0800] Liquid E-a was prepared in the same manner as in Example a1 except that the compounds shown in Table 9 were used as Component A5 and the amounts of the reagent MAA and Component A5 were changed as shown in Table 9.

[0801] Next, a composition containing MAA was prepared in the same manner as in Example a1 except that the amounts of reagent MAA and E-a solution were changed as shown in the table. The concentrations of the components in the composition containing methacrylic acid are shown in Table 10. The reduction rate of the polymerization inhibitor (component B1) in the composition containing methacrylic acid after storage at 25° C. for 21 days is shown in Table 10.

[0802] (Example e10)

[0803] A methacrylic acid-containing composition was prepared in the same manner as in Example a4 except that isobutyric acid was used as Component A5. The concentrations of the components in the methacrylic acid-containing composition are shown in Table 10. The reduction rate of the polymerization inhibitor (Component B1) in the methacrylic acid-containing composition after storage at 25° C. for 21 days is shown in Table 10.

[0804] (Example e11)

[0805] A methacrylic acid-containing composition was prepared in the same manner as in Example a6 except that isobutyric acid was used as Component A5. The concentrations of the components in the methacrylic acid-containing composition are shown in Table 10. The reduction rate of the polymerization inhibitor (Component B1) in the methacrylic acid-containing composition after storage at 25° C. for 21 days is shown in Table 10.

[0806] (Example e12)

[0807] A methacrylic acid-containing composition was prepared in the same manner as in Example a7 except that isobutyric acid was used as Component A5. The concentrations of the components in the methacrylic acid-containing composition are shown in Table 10. The reduction rate of the polymerization inhibitor (Component B1) in the methacrylic acid-containing composition after storage at 25° C. for 21 days is shown in Table 10.

[0808] (Comparative Example e1)

[0809] A methacrylic acid-containing composition was prepared by the same method as in Comparative Example b1 except that isobutyric acid was used as Component A5. The concentrations of the components in the methacrylic acid-containing composition are shown in Table 10. The reduction rate of the polymerization inhibitor (Component B1) in the methacrylic acid-containing composition after storage at 25° C. for 21 days is shown in Table 10.

[0810]

[0811]

[0812] As shown in Tables 9 and 10, in Examples e1 to e12, the decomposition of the polymerization inhibitor (component B1) in the methacrylic acid composition after storage was suppressed. It can be said that the quality stability during storage is high.

[0813] (Examples f1-f10)

[0814] The compounds shown in Table 11 were used as Component A6, and the amounts of the reagent MAA and Component A6 were changed as shown in Table 11. In the same manner as in Example a1, F-a solutions were prepared.

[0815] Next, compositions containing MAA were prepared in the same manner as in Example a1 except that the amounts of reagent MAA and F-a solution were changed as shown in the table. The concentrations of the components in the compositions containing methacrylic acid are shown in Table 12. The reduction rate of the polymerization inhibitor (component B1) in the compositions containing methacrylic acid after storage at 25° C. for 21 days is shown in Table 12.

[0816]

[0817]

[0818] As shown in Tables 11 and 12, in Examples f1 to f10, the decomposition of the polymerization inhibitor (component B1) in the methacrylic acid composition after storage was suppressed. It can be said that the quality stability during storage is high.

[0819] By esterifying the methacrylic acid-containing composition obtained in this example, a methacrylic acid ester can be obtained. Also, by polymerizing a polymerizable composition containing the methacrylic acid-containing composition obtained in this example, a methacrylic acid polymer can be obtained.

[0820] Industrial Applicability

[0821] According to the present invention, it is possible to provide a methacrylic acid-containing composition in which decomposition of a polymerization inhibitor during storage is suppressed and which has high quality stability.

[0822] According to the present invention, a composition containing methacrylic acid which can be used as a raw material for acrylic resin or the like can be stably stored for a long period of time, and the present invention is industrially useful.

Claims

1. A composition containing methacrylic acid, comprising: Methacrylic acid, and at least one selected from the group consisting of a compound represented by the following formula (11), namely component A1; a compound represented by the following formula (21), namely component A21; a compound represented by the following formula (31), namely component A3; a compound represented by the following formula (41), namely component A4; a compound represented by the following formula (51), namely component A5; and a compound represented by the following formula (61), namely component A6; Furthermore, the component B as a polymerization inhibitor may be optionally contained as required. The concentration of methacrylic acid is 98.00 to 99.99% by mass. In formula (11), R 1a , R 2a , R 3a , R 4a , R 5a and R 6a each independently represents a hydrogen atom, an alkyl group, an alkenyl group, a hydroxyl group, an alkoxy group, an amino group, a monovalent group containing a carbonyl group, an alkylthio group or an arylthio group, R 1a , R 2a , R 3a , R 4a and R 5a Two or more of them are groups other than hydrogen atoms, R 7a represents a hydrogen atom, an alkenyl group, an aryl group, a hydroxyl group, an alkoxy group, an amino group, a monovalent group including a carbonyl group, an alkylthio group or an arylthio group, In formula (21), R 1b , R 2b , R 3b and R 4b each independently represents a hydrogen atom, an alkyl group, an alkenyl group, an aryl group, a hydroxyl group, an alkoxy group, an amino group, a monovalent group containing a carbonyl group, an alkylthio group or an arylthio group, In formula (31), R 1c , R 2c , R 3c , R 4c , R 5c , R 6c and R 7c independently represent a hydrogen atom, an alkyl group, an alkenyl group, an aryl group, a hydroxyl group, an alkoxy group, an amino group, a monovalent group containing a carbonyl group, an alkylthio group or an arylthio group, R d -C≡N…(41) In formula (41), R d represents an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, or an aryl group having 1 to 12 carbon atoms, and these groups may further have a substituent, In formula (51), R 1e and R 2e each independently represents a hydrogen atom, an alkyl group, an alkenyl group, an aryl group, a hydroxyl group, an alkoxy group, an alkylthio group or an arylthio group, R 3e represents a hydrogen atom, an alkyl group, an alkenyl group, an aryl group, a hydroxyl group, an alkoxy group, an amino group, an alkylthio group or an arylthio group, R 1e With R 2e , R 2e With R 3e , R 3e With R 1e can be connected to each other to form a ring, in, R 1e With R 2e The total number of carbon atoms is 2 or more, In formula (61), R 1f , R 2f and R 3f each independently represents a hydrogen atom, an alkyl group, an alkenyl group, an aryl group, a hydroxyl group, an alkoxy group, an amino group, an alkylthio group or an arylthio group, R 4f represents an alkyl group, an alkenyl group, an aryl group, a hydroxyl group, an alkoxy group, an amino group, a monovalent group containing a carbonyl group, an alkylthio group or an arylthio group, Among them, R is not included 1f =H, R 2f =H, R 3f =CH3 and R 4f =OH, that is, when the component A6 is methacrylic acid, H represents a hydrogen atom, C represents a carbon atom, O represents an oxygen atom, and R 1f , R 2f and R 3f The total number of carbon atoms is 1 or more.

2. The methacrylic acid-containing composition according to claim 1, wherein The concentration of the component A1 is set to M A1 , the unit is μmol / L, and the concentration of the component B is set to M B , when the unit is μmol / L, M B / M A1 It is 0.005~100.

3. The methacrylic acid-containing composition according to claim 1, wherein The concentration of the component A1 is set to M A1 , when the unit is μmol / L, M A1 1~50000μmol / L.

4. The methacrylic acid-containing composition according to claim 3, wherein The M A1 It is 10~30000μmol / L.

5. The methacrylic acid-containing composition according to claim 1, wherein The concentration of the component A21 is set to M A21 , the unit is μmol / L, and the concentration of the component B is set to M B , when the unit is μmol / L, M B / M A21 It is 0.005~100.

6. The methacrylic acid-containing composition according to claim 1, wherein The concentration of the component A21 is set to M A21 , when the unit is μmol / L, M A21 1~50000μmol / L.

7. The methacrylic acid-containing composition according to claim 6, wherein The M A21 It is 10~30000μmol / L.

8. The methacrylic acid-containing composition according to claim 1, wherein The concentration of the component A3 is set to M A3 , when the unit is μmol / L, M A3 1~50000μmol / L.

9. The methacrylic acid-containing composition according to claim 8, wherein The M A3 It is 10~30000μmol / L.

10. The methacrylic acid-containing composition according to claim 1, wherein The concentration of the component A3 is set to M A3 , the unit is μmol / L, and the concentration of the component B is set to M B When the unit is μmol / L, M B / M A3 It is 0.005~100.

11. The methacrylic acid-containing composition according to claim 1, wherein The concentration of the component A4 is set to M A4 The unit is μmol / L, and the concentration of the component B is set to M B When the unit is μmol / L, M B / M A4 It is 0.005~100.

12. The methacrylic acid-containing composition according to claim 1, wherein The concentration of the component A4 is set to M A4 , when the unit is μmol / L, M A4 1~20000μmol / L.

13. The methacrylic acid-containing composition according to claim 12, wherein The M A4 It is 10~15000μmol / L.

14. The methacrylic acid-containing composition according to claim 1, wherein The concentration of the component A5 is set to M A5 , the unit is μmol / L, and the concentration of the component B is set to M B , when the unit is μmol / L, M B / M A5 It is 0.005~100.

15. The methacrylic acid-containing composition according to claim 1, wherein The concentration of the component A5 is set to M A5 , when the unit is μmol / L, M A5 1~50000μmol / L.

16. The methacrylic acid-containing composition according to claim 15, wherein The M A5 It is 10~30000μmol / L.

17. The methacrylic acid-containing composition according to claim 1, wherein The concentration of the component A6 is set to M A6 , the unit is μmol / L, and the concentration of the component B is set to M B , when the unit is μmol / L, M B / M A6 It is 0.005~100.

18. The methacrylic acid-containing composition according to claim 1, wherein The concentration of component A is set to M A6 , when the unit is μmol / L, M A6 1~85000μmol / L.

19. The methacrylic acid-containing composition according to claim 18, wherein The M A6 It is 10~40000μmol / L.

20. The methacrylic acid-containing composition according to claim 1, wherein The concentration of component B is set to M B , when the unit is μmol / L, M B 1~50000μmol / L.

21. The methacrylic acid-containing composition according to claim 20, wherein The M B It is 10~10000μmol / L.

22. The methacrylic acid-containing composition according to claim 1, wherein in formula (11), R 1a , R 2a , R 3a , R 4a , R 5a and R 6a each independently represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, an aryl group having 1 to 12 carbon atoms, a hydroxyl group, an alkoxy group having 1 to 6 carbon atoms, an amino group having 0 to 6 carbon atoms, or a monovalent group containing a carbonyl group having 1 to 6 carbon atoms, R 7a It is a hydrogen atom, an alkenyl group having 2 to 5 carbon atoms, an aryl group having 1 to 12 carbon atoms, a hydroxyl group, an alkoxy group having 1 to 6 carbon atoms, an amino group having 0 to 6 carbon atoms, or a monovalent group including a carbonyl group having 1 to 6 carbon atoms.

23. The methacrylic acid-containing composition according to claim 1, wherein in formula (11), R 1a , R 2a , R 3a , R 4a , R 5a and R 6a are each independently a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, a hydroxyl group, or an alkoxy group having 1 to 6 carbon atoms, R 7a It is a hydrogen atom, a carboxyl group or an alkoxycarbonyl group having 2 to 6 carbon atoms.

24. The methacrylic acid-containing composition according to claim 1, wherein in formula (11), R 1a , R 2a , R 3a , R 4a , R 5a and R 6a are each independently a hydrogen atom, a methyl group, an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, a sec-butyl group, an isobutyl group, a tert-butyl group, a hydroxyl group or a methoxy group, R 7a is a hydrogen atom, a carboxyl group or a methoxycarbonyl group.

25. The methacrylic acid-containing composition according to claim 1, wherein in formula (21), R 1b , R 2b , R 3b and R 4b Each is independently a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, an aryl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an amino group having 0 to 6 carbon atoms, a monovalent group containing a carbonyl group having 1 to 6 carbon atoms, an alkylthio group having 1 to 5 carbon atoms, or an arylthio group having 6 to 10 carbon atoms.

26. The methacrylic acid-containing composition according to claim 1, wherein in formula (21), R 1b , R 2b , R 3b and R 4b Each is independently a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms.

27. The methacrylic acid-containing composition according to claim 1, wherein in formula (21), R 1b , R 2b , R 3b and R 4b Each is independently a hydrogen atom, a methyl group, an ethyl group, a n-propyl group, an isopropyl group, or a methoxy group.

28. The methacrylic acid-containing composition according to claim 1, wherein in formula (31), R 1c , R 2c , R 3c , R 4c , R 5c , R 6c and R 7c Each is independently a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, an aryl group having 1 to 12 carbon atoms, a hydroxyl group, an alkoxy group having 1 to 6 carbon atoms, an amino group having 0 to 6 carbon atoms, or a monovalent group having 1 to 6 carbon atoms and including a carbonyl group.

29. The methacrylic acid-containing composition according to claim 1, wherein in formula (31), R 1c , R 2c , R 3c , R 4c , R 5c , R 6c and R 7c Each is independently a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, a hydroxyl group, an alkoxy group having 1 to 5 carbon atoms, a carboxyl group, or an alkoxycarbonyl group having 2 to 6 carbon atoms.

30. The methacrylic acid-containing composition according to claim 1, wherein in formula (31), R 1c , R 2c , R 3c , R 4c , R 5c , R 6c and R 7c Each is independently a hydrogen atom, a methyl group, an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, a sec-butyl group, an isobutyl group, a tert-butyl group, a hydroxyl group, a methoxy group, a carboxyl group or a methoxycarbonyl group.

31. The methacrylic acid-containing composition according to claim 1, wherein in formula (41), R d It is an alkyl group having 1 to 3 carbon atoms, an alkenyl group having 2 to 3 carbon atoms, or an aryl group having 6 to 8 carbon atoms.

32. The methacrylic acid-containing composition according to claim 1, wherein in formula (41), R d It is methyl, ethyl, vinyl, isopropenyl or phenyl.

33. The methacrylic acid-containing composition according to claim 1, wherein in formula (51), R 1e and R 2e each independently represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, an aryl group having 1 to 12 carbon atoms, a hydroxyl group, an alkoxy group having 1 to 6 carbon atoms, an alkylthio group having 1 to 5 carbon atoms, or an arylthio group having 6 to 10 carbon atoms, R 3e It is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, an aryl group having 1 to 12 carbon atoms, a hydroxyl group, an alkoxy group having 1 to 6 carbon atoms, an amino group having 0 to 6 carbon atoms, an alkylthio group having 1 to 5 carbon atoms, or an arylthio group having 6 to 10 carbon atoms.

34. The methacrylic acid-containing composition according to claim 1, wherein in formula (51), R 1e and R 2e are each independently a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, R 3e It is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, a hydroxyl group, or an alkoxy group having 1 to 6 carbon atoms.

35. The methacrylic acid-containing composition according to claim 1, wherein in formula (51), R 1e and R 2e are each independently a hydrogen atom, a methyl group, an ethyl group, a n-propyl group or an isopropyl group, R 3e It is hydroxyl.

36. The methacrylic acid-containing composition according to claim 1, wherein in formula (61), R 1f , R 2f and R 3f each independently represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an aryl group having 1 to 12 carbon atoms, a hydroxyl group, an alkoxy group having 1 to 6 carbon atoms, an amino group having 0 to 6 carbon atoms, a monovalent group containing a carbonyl group having 1 to 6 carbon atoms, an alkylthio group having 1 to 5 carbon atoms, or an arylthio group having 6 to 10 carbon atoms, R 4f It is an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an aryl group having 1 to 12 carbon atoms, a hydroxyl group, an alkoxy group having 1 to 6 carbon atoms, an amino group having 0 to 6 carbon atoms, a monovalent group containing a carbonyl group having 1 to 6 carbon atoms, an alkylthio group having 1 to 5 carbon atoms, or an arylthio group having 6 to 10 carbon atoms.

37. The methacrylic acid-containing composition according to claim 1, wherein in formula (61), R 1f , R 2f and R 3f are each independently a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, R 4f It is an alkyl group having 1 to 5 carbon atoms, a hydroxy group, or an alkoxy group having 1 to 6 carbon atoms.

38. The methacrylic acid-containing composition according to claim 1, wherein in formula (61), R 1f , R 2f and R 3f are each independently a hydrogen atom, a methyl group, an ethyl group, a n-propyl group or an isopropyl group, R 4f It is hydroxyl.

39. The methacrylic acid-containing composition according to claim 1, wherein The molecular weight of the component A1 is 2,000 or less.

40. The methacrylic acid-containing composition according to claim 1, wherein The molecular weight of the component A21 is 1,000 or less.

41. The methacrylic acid-containing composition according to claim 1, wherein The molecular weight of the component A3 is 2,000 or less.

42. The methacrylic acid-containing composition according to claim 1, wherein The molecular weight of the component A4 is 1,000 or less.

43. The methacrylic acid-containing composition according to claim 1, wherein The molecular weight of the component A5 is 1,000 or less.

44. The methacrylic acid-containing composition according to claim 1, wherein The molecular weight of the component A6 is 1,000 or less.

45. The methacrylic acid-containing composition according to claim 1, wherein The component B is at least one selected from phenolic compounds, quinone compounds, nitrobenzene compounds, N-oxyl radical compounds, amine compounds, phosphorus-containing compounds, sulfur-containing compounds, iron-containing compounds, copper-containing compounds and manganese-containing compounds.

46. ​​The methacrylic acid-containing composition according to claim 1, wherein The component B is at least one selected from the group consisting of phenolic compounds, N-oxyl radical compounds, amine compounds, phosphorus-containing compounds, and sulfur-containing compounds.

47. The methacrylic acid-containing composition according to claim 1, wherein The component B is a phenolic compound.

48. The methacrylic acid-containing composition according to claim 1, wherein The component B is at least one selected from the group consisting of hydroquinone, 4-methoxyphenol, 2,4-dimethyl-6-tert-butylphenol, 2,6-di-tert-butyl-4-methylphenol, 4-hydroxy-2,2,6,6-tetramethylpiperidinyl-N-oxyl free radical, N,N-diphenylamine, N-nitrosodiphenylamine, triphenyl phosphite and phenothiazine.

49. The methacrylic acid-containing composition according to claim 1, wherein The component B is at least one selected from the group consisting of hydroquinone, 4-methoxyphenol, 2,4-dimethyl-6-tert-butylphenol and 2,6-di-tert-butyl-4-methylphenol.

50. The methacrylic acid-containing composition according to claim 1, wherein The concentration of methacrylic acid is 98.50 to 99.99% by mass. The methacrylic acid-containing composition according to claim 1 , which contains no diacetyl or contains diacetyl at a concentration of 55 μmol / L or less.

52. A method for producing a methacrylic acid ester, comprising the step of esterifying the methacrylic acid in the composition containing methacrylic acid according to any one of claims 1 to 51.

53. A polymerizable composition comprising the methacrylic acid-containing composition according to any one of claims 1 to 51.

54. The polymerizable composition according to claim 53, wherein It further contains a monomer copolymerizable with methacrylic acid.

55. A method for producing a methacrylic acid polymer, comprising the step of polymerizing a polymerizable composition comprising the methacrylic acid-containing composition according to any one of claims 1 to 51.

56. The manufacturing method according to claim 55, wherein: The polymerizable composition further contains a monomer copolymerizable with methacrylic acid.

57. The manufacturing method according to claim 56, wherein: The polymerizable composition contains 50 parts by mass or more of a monomer copolymerizable with methacrylic acid based on 100 parts by mass of the polymerizable composition.

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