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

Abstract

The purpose of the present invention is to provide a methacrylate–containing composition that has high quality stability during storage.　The methacrylate-containing composition according to one example contains methacrylate, a compound (component A1) represented by formula (11), and a polymerization inhibitor (component B), wherein the concentration of the methacrylate is 98.00-99.99 mass%. R1a, R2a, R3a, R4a, R5a and R6a are: a monovalent group comprising a hydrogen atom, an alkyl group, an alkenyl group, an aryl group, a hydroxy group, an alkoxy group, an amino group, and a carbonyl group; an alkylthio group; or an arylthio group.　At least two among R1a, R2a, R3a, R4a and R5a are a group other than a hydrogen atom.　R7a is: a monovalent group comprising a hydrogen atom, an alkenyl group, an aryl group, a hydroxy group, an alkoxy group, an amino group, and a carbonyl group; an alkylthio group; or an arylthio group.

Description

[Technical Field]

[0001] The present invention relates to a methacrylic acid-containing composition, a method for producing a methacrylic acid ester, a polymerizable composition, and a method for producing a methacrylic acid polymer. This application claims priority based on Japanese Patent Applications No. 2022-172927, 2022-172928, 2022-173123, 2022-173124, 2022-173222, and 2022-173223, which were filed with the Japan Patent Office on 28 October 2022, and the contents thereof are incorporated herein by reference. [Background technology]

[0002] Methacrylic acid (hereinafter also referred to as "MAA") is known to be an extremely useful substance used as an industrially important methacrylic acid ester and as a raw material for various types and applications of polymers. For example, polymethyl methacrylate, a homopolymer of methyl methacrylate, is used in signage, lighting equipment, automotive parts, building materials, light guide plates for flat displays, light diffusers, etc., taking advantage of its excellent transparency and weather resistance. Furthermore, copolymers of methacrylic acid with other monomers are used in paints, adhesives, textile treatment agents, resin modifiers, rubber modifiers, leather treatment agents, paper processing agents, lubricant additives, cement admixtures, concrete admixtures, latex, photosensitive resins, ion exchange resins, water treatment polymers, etc. Various methods have been developed for the industrial production of methacrylic acid, for example, as a byproduct of the acetone cyanohydrin (ACH) method or as an intermediate in the C4 direct oxidation method (Non-Patent Literature 1). In these manufacturing methods, the methacrylic acid produced is purified by methods such as distillation or crystallization to remove unreacted raw materials and by-products, thereby obtaining methacrylic acid of a quality suitable for the intended application.

[0003] Because methacrylic acid is easily polymerized, it is known that polymerization inhibitors are added to maintain the quality of methacrylic acid during its production and storage (Non-Patent Document 2). For example, Patent Document 1 states that among various polymerization inhibitors, methyl ether of hydroquinone (MEHQ) is particularly preferred. Patent Document 2 states that phenothiazine and hydroquinone are added as polymerization inhibitors to a methacrylic acid-containing substance. Patent Document 3 states that methacrylic acid is distilled in the presence of 4-methoxyphenol, which is a polymerization inhibitor. Patent Document 4 states that diphenylamine derivatives are used as polymerization inhibitors. Patent Document 5 states that benzenetriamine derivatives are used as polymerization inhibitors. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2004-155757 [Patent Document 2] Japanese Patent Publication No. 2001-072639 [Patent Document 3] Japanese Patent Publication No. 2008-101013 [Patent Document 4] Special Publication No. 2002-533309 [Patent Document 5] Special Publication No. 2002-513034 [Non-patent literature]

[0005] [Non-Patent Document 1] Kuroda, Toru, "Development of a catalyst for the production of methyl methacrylate," Catalysis, The Catalysis Society of Japan, 2003, Vol. 45, No. 5, pp. 366-371. [Non-Patent Document 2] Takayuki Otsu, "On the Function of Polymerization Inhibitors," Organic Synthesis Chemistry, The Society of Organic Synthesis, 1975, Vol. 33, No. 8, pp. 634-640. [Overview of the project] [Problems that the invention aims to solve]

[0006] However, even when the polymerization inhibitor is added, methacrylic acid may deteriorate in quality during storage. Therefore, the present invention provides a methacrylic acid-containing composition that has high quality stability during storage. [Means for solving the problem]

[0007] The inventors diligently conducted research to achieve the above objectives. As a result, they discovered that the inclusion of a compound with a specific structure in the methacrylic acid-containing composition improves its quality stability during storage and suppresses the decomposition of polymerization inhibitors, thus completing the present invention.

[0008] According to one aspect of the present invention, the following methacrylic acid-containing composition is provided. Methacrylic acid and, At least one selected from the group consisting of component A1, which is a compound represented by the following formula (11); component A21, which is a compound represented by the following formula (21); component A3, which is a compound represented by the following formula (31); component A4, which is a compound represented by the following formula (41); component A5, which is a compound represented by the following formula (51); and component A6, which is a compound represented by the following formula (61). It contains, Furthermore, it optionally contains component B, which is a polymerization inhibitor, A methacrylic acid-containing composition having a methacrylic acid concentration of 98.00 to 99.99% by mass.

[0009] [ka]

[0010] In formula (11), R 1a , R 2a , R 3a , R 4a , R 5a and R 6aEach independently represents a hydrogen atom, an alkyl group, an alkenyl group, a hydroxy 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 a hydrogen atom. R 7a represents a hydrogen atom, an alkenyl group, an aryl group, a hydroxy group, an alkoxy group, an amino group, a monovalent group containing a carbonyl group, an alkylthio group or an arylthio group.

[0011]

Chemical formula

[0012] 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 hydroxy group, an alkoxy group, an amino group, a monovalent group containing a carbonyl group, an alkylthio group or an arylthio group.

[0013]

Chemical formula

[0014] 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 hydroxy group, an alkoxy group, an amino group, a monovalent group containing a carbonyl group, an alkylthio group or an arylthio group.

[0015]

Chemical formula

[0016] 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 substituents.

[0017] [ka]

[0018] In formula (51), R 1e and R 2e Each of these 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 This represents a hydrogen atom, alkyl group, alkenyl group, aryl group, hydroxyl group, alkoxy group, amino group, alkylthio group, or arylthio group. R 1e and R 2e , R 2e and R 3e , R 3e and R 1e These may be connected to each other to form a ring. However, R 1e and R 2e The total number of carbon atoms is 2 or more.

[0019] [ka]

[0020] In formula (61), R 1f , R 2f and R 3f Each of these 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 4fThis represents a monovalent group including an alkyl group, alkenyl group, aryl group, hydroxyl group, alkoxy group, amino group, or carbonyl group, as well as an alkylthio group or arylthio group. However, R 1f =H and R 2f =H and R 3f =CH3 and R 4f Except when =OH, i.e., when component A6 is methacrylic acid. Also, R 1f , R 2f and R 3f The total number of carbon atoms is 1 or more. H represents a hydrogen atom, C represents a carbon atom, and O represents an oxygen atom.

[0021] According to yet another aspect of the present invention, a method for producing a methacrylic acid ester is provided, which includes esterifying the methacrylic acid in the methacrylic acid-containing composition.

[0022] According to yet another aspect of the present invention, a polymerizable composition containing the methacrylic acid-containing composition is provided.

[0023] According to yet another aspect of the present invention, a method for producing a methacrylic acid polymer is provided, comprising polymerizing the polymerizable composition. [Effects of the Invention]

[0024] According to the present invention, it is possible to provide a methacrylic acid-containing composition with high quality stability in which the decomposition of polymerization inhibitors during storage is suppressed. [Modes for carrying out the invention]

[0025] The following describes several embodiments, but the present invention is not limited to these. In this specification, a numerical range represented by "~" means a range that includes the numbers written before and after "~" as the lower and upper limits, and "A~B" means A or greater and B or less. A new numerical range can be created by arbitrarily combining the lower and upper limits of the numerical ranges disclosed in this specification.

[0026] [Methacrylic acid-containing composition according to the first embodiment] The methacrylic acid-containing composition according to the first embodiment contains methacrylic acid, component A1 which is a compound represented by the following formula (11), and component B which is a polymerization inhibitor. The concentration of methacrylic acid is 98.00 to 99.99% by mass.

[0027] [ka]

[0028] In formula (11), R 1a , R 2a , R 3a , R 4a , R 5a and R 6a Each of these independently represents a hydrogen atom, an alkyl group, an alkenyl group, a hydroxyl group, an alkoxy group, an amino group, a carbonyl group, a monovalent group, an alkylthio group, or an arylthio group, and R 1a , R 2a , R 3a , R 4a and R 5a Two or more of these are groups other than hydrogen atoms. 7a This represents a hydrogen atom, an alkenyl group, an aryl group, a hydroxyl group, an alkoxy group, an amino group, a carbonyl group, a monovalent group, an alkylthio group, or an arylthio group. Furthermore, the methacrylic acid-containing composition may also contain other compounds (component C) or water, as long as the concentration of methacrylic acid satisfies 98.00 to 99.99% by mass. Each item will be explained in detail below.

[0029] (Methacrylic acid) The methacrylic acid-containing composition according to the first embodiment contains methacrylic acid. Methacrylic acid can be produced, for example, as a by-product of the acetone cyanohydrin (ACH) process or as an intermediate of the C4 direct oxidation process. The methacrylic acid contained in the methacrylic acid-containing composition is preferably produced by the C4 direct oxidation process, and more preferably produced by the C4 direct oxidation process using biomass-derived isobutanol as a starting material.

[0030] (Component A1) The methacrylic acid-containing composition according to the first embodiment contains component A1, which is a compound represented by formula (11). The coexistence of component A1 and component B, described later, can suppress the decomposition of polymerization inhibitors during storage of the methacrylic acid-containing composition. The reason for this is presumed to be as follows.

[0031] Methacrylic acid is known to polymerize due to radicals generated during storage, and a polymerization inhibitor (component B) is added to prevent polymerization. Component B has a polymerization inhibitory function by trapping radicals generated during the storage of methacrylic acid. However, because the polymerization inhibitor decomposes into other compounds when trapping radicals, the concentration of component B in the methacrylic acid-containing composition gradually decreases during storage, and the polymerization inhibitory function gradually deteriorates. Furthermore, the amount of unwanted decomposition products generated by component B trapping radicals gradually increases. An example of a radical generated during the storage of methacrylic acid is the hydroxyl radical, which is generated when an oxygen molecule absorbs ultraviolet light from sunlight. Component A1 is a π-conjugated compound having a benzene ring, and therefore absorbs ultraviolet light, with its absorption wavelength and intensity varying depending on the type of substituent. Component A1 has an alkyl group with appropriate bulk and electron-donating properties bonded to the benzene ring, so it can absorb ultraviolet light across a wide range of wavelengths. Therefore, when a methacrylic acid-containing composition contains component A1, ultraviolet light across a wide range of wavelengths is absorbed, and the generation of hydroxyl radicals is suppressed. Therefore, since the number of radicals that component B needs to trap is reduced, the decrease in the concentration of component B and the generation of degradation products can be suppressed.

[0032] The molecular weight of component A1 is preferably 2000 or less. By having a molecular weight of 2000 or less, the number of benzene rings per unit mass in component A1 can be increased, so that the effects of the present invention can be obtained with a small mass. The molecular weight of component A1 is more preferably 1600 or less, even more preferably 1200 or less, and particularly preferably 800 or less.

[0033] R in equation (11) 1a , R 2a , R 3a , R 4a , R 5a and R 6a Each of these independently represents a hydrogen atom, an alkyl group, an alkenyl group, a hydroxyl group, an alkoxy group, an amino group, a carbonyl group, a monovalent group, an alkylthio group, or an arylthio group. Also, in formula (11) above, R 7a R represents a monovalent group containing a hydrogen atom, an alkenyl group, an aryl group, a hydroxyl group, an alkoxy group, an amino group, or a carbonyl group, and R represents a monovalent group containing an alkylthio group or an arylthio group. 1a , R 2a , R 3a , R 4a and R 5a Two or more of these 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 carbonyl group, a monovalent group, an alkylthio group, or an arylthio group. 1a , R 2a , R 3a , R 4a , R 5a , R 6a and R 7a These may be the same or different.

[0034] In the above equation (11), R 1a , R 2a , R 3a , R 4a , R 5a , R 6a and R 7a If the steric hindrance is large, distortion occurs in the benzene ring, and the π-conjugated system cannot be maintained, R 1a , R2a and R 3a and R 4a and R 5a and R 6a and R 7a When R satisfies the above conditions, it has an appropriate bulkiness, and since the π-conjugated system of component A1 is maintained, it has the property of absorbing ultraviolet light with a wide range of wavelengths, and the effects of the present invention can be obtained. From the viewpoint of increasing the absorbance of ultraviolet light and suppressing the generation of hydroxyl radicals, R 1a and R 2a and R 3a and R 4a and R 5a and R 6a are preferably monovalent groups containing a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, a hydroxy group, an alkoxycarbonyl group having 1 to 6 carbon atoms, an amino group having 0 to 6 carbon atoms, or a carbonyl group having 1 to 6 carbon atoms, more preferably a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, a hydroxy group, or an alkoxycarbonyl group having 1 to 6 carbon atoms, still more preferably a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an s-butyl group, an i-butyl group, a hydroxy group, or a methoxy group, and particularly preferably a hydrogen atom, a hydroxy group, or a methoxy group. Also, from the viewpoint of increasing the absorbance of ultraviolet light and suppressing the generation of hydroxyl radicals, R 7a is preferably a monovalent group containing a hydrogen atom, an alkenyl group having 2 to 5 carbon atoms, an aryl group having 6 to 12 carbon atoms, a hydroxy group, an alkoxycarbonyl group having 1 to 6 carbon atoms, an amino group having 0 to 6 carbon atoms, or a carbonyl group having 1 to 6 carbon atoms, more preferably a hydrogen atom, a carboxy group, or an alkoxycarbonyl group having 2 to 6 carbon atoms, and still more preferably a hydrogen atom, a carboxy group, or a methoxycarbonyl group.

[0035] The alkyl group is a linear (linear or branched) alkyl group or a cyclic alkyl group. Alkyl groups having 1 to 20 carbon atoms are preferred, alkyl groups having 1 to 10 carbon atoms are more preferred, and alkyl groups having 1 to 5 carbon atoms are even more preferred. Examples of linear alkyl groups include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, s-butyl group, t-butyl group, n-pentyl group, isopentyl group, hexyl group, octyl group, decyl group, hydroxymethyl group, 1-hydroxyethyl group, and 2-hydroxyethyl group, with methyl group, ethyl group, n-propyl group, isopropyl group, and t-butyl group being preferred. Examples of cyclic alkyl groups include cyclopentyl group, cyclohexyl group, and cyclooctyl group.

[0036] The alkenyl group is a linear (linear or branched) alkenyl group or a cyclic alkenyl group. Alkenyl groups with 2 to 20 carbon atoms are preferred, alkenyl groups with 2 to 10 carbon atoms are more preferred, and alkenyl groups with 2 to 5 carbon atoms are even more preferred. Examples of linear alkenyl groups include vinyl, 1-propenyl, isopropenyl, 2-butenyl, 1,3-butadienyl, 2-pentenyl, and 2-hexenyl groups. Examples of cyclic alkenyl groups include cyclopentenyl and cyclohexenyl groups.

[0037] 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 heteroaryl groups containing oxygen, nitrogen, sulfur, etc. Examples of aryl groups include phenyl, mesityl, naphthyl, 2-methylphenyl, 3-methylphenyl, 4-methylphenyl, 2,3-dimethylphenyl, 2,4-dimethylphenyl, 2,5-dimethylphenyl, 2,6-dimethylphenyl, 2-ethylphenyl, isoxazolyl, isothiazolyl, imidazolyl, oxazolyl, thiazolyl, thiadiazolyl, thienyl, triazolyl, tetrazolyl, pyridyl, pyrazinyl, pyrimidinyl, pyridadinyl, pyrazolyl, pyrrolyl, furyl, fluzanyl, isoquinolyl, isoindolyl, indolyl, quinolyl, pyridothiazolyl, benzimidazolyl, benzoxazolyl, benzothiazolyl, benzotriazolyl, benzofuranyl, imidazopyridinyl, triazopyridinyl, and prinyl groups.

[0038] 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 even more preferably an alkoxy group having 1 to 6 carbon atoms. Examples of alkoxy groups include methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, s-butoxy, t-butoxy, n-pentoxy, isopentoxy, and phenoxy groups.

[0039] The amino group includes an amino group (-NH2) (0 carbon atoms) with no substituents on the nitrogen atom, and an amino group in which some or all of the hydrogen atoms bonded to the nitrogen atom are substituted with carbon atoms. The number of carbon atoms in the amino group in which some 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 even more preferably 1 to 6. Examples of amino groups include an unsubstituted amino group (-NH2), methylamino group, ethylamino group, propylamino group, butylamino group, dimethylamino group, diethylamino group, anilino group, toluidino group, anisidino group, diphenylamino group, and N-methyl-N-phenylamino group.

[0040] Examples of monovalent groups containing a carbonyl group include formyl group, acyl group, carboxyl group, amide group, alkoxycarbonyl group, thiocarboxyl group, thioester group, etc., with monovalent groups containing a carbonyl group having 1 to 6 carbon atoms being preferred.

[0041] An acyl group is a substituent formed by linking a carbonyl group with an alkyl group, alkenyl group, or aryl group. The total number of carbon atoms derived from the carbonyl group (1) and the alkyl group, alkenyl group, or aryl group of the acyl group is preferably 2 to 20, more preferably 2 to 10, and even more preferably 2 to 6. Examples of acyl groups include acetyl group, propionyl group, butylcarbonyl group, vinylcarbonyl group, and benzoyl group.

[0042] The amide group includes an amide group (-CONH2) without substituents on the nitrogen atom, and an amide group in which some or all of the hydrogen atoms bonded to the nitrogen atom are substituted with carbon atoms. The total number of carbon atoms in the amide group is the sum of the carbon atoms derived from the carbonyl group (1) and the carbon atoms substituted on the nitrogen atom, which is preferably 1 to 20, more preferably 1 to 10, and even more preferably 1 to 5. Examples of amide groups include unsubstituted amide groups, N-methylamide groups, N-ethylamide groups, N-phenylamide groups, N,N-dimethylamide groups, and N-methyl-N-phenylamide groups.

[0043] An alkoxycarbonyl group is a substituent formed by linking a carbonyl group and an alkoxy group, and is also called an ester group. The total number of carbon atoms from the carbonyl group (1) and the alkoxy group is preferably 2 to 20, more preferably 2 to 10, and even more preferably 2 to 6. Examples of alkoxycarbonyl groups include methoxycarbonyl group, ethoxycarbonyl group, butoxycarbonyl group, and phenoxycarbonyl group.

[0044] A thioester group is a substituent formed by linking a carbonyl group with an alkylthio or arylthio group. The total number of carbon atoms derived from the carbonyl group (1) and the alkylthio or arylthio group is preferably 2 to 20, more preferably 2 to 10, and even more preferably 2 to 6. Examples of thioester groups include methylthiocarbonyl group, ethylthiocarbonyl group, butylthiocarbonyl group, and phenylthiocarbonyl group.

[0045] Furthermore, the monovalent group containing a carbonyl group may be a substituent in which one or more hydrogen atoms of an alkyl group are substituted with a carbonyl group. Examples of such substituents include 2-acetoxyethyl group, 2-acetoethyl group, and 2-(acetoacetoxy)ethyl group.

[0046] 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 even more preferably an alkylthio group having 1 to 5 carbon atoms. Examples of alkylthio groups include methylthio group, ethylthio group, propylthio group, isopropylthio group, and the like.

[0047] 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 even more preferably an arylthio group having 6 to 10 carbon atoms. Examples of arylthio groups include phenylthio groups and tolylthio groups.

[0048] Among the compounds that satisfy the above conditions, from the viewpoint of quality stability during storage of the methacrylic acid-containing composition, component A1 is 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-methylpropionate, methyl 2-(2-methoxy-5-hydroxyphenyl)-2-methylpropionate, or 2-(2,5-dihydroxyphenyl Methyl 2-methylpropionate is preferred, methyl 2-phenylisobutyrate, 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 is more preferred, methyl 2-phenylisobutyrate, 2-phenylisobutyric acid, 2-isopropylhydroquinone, 2-isopropyl-4-methoxyphenol, 2-(2-hydroxy-5-methoxyphenyl)-2-methylpropionic acid is even more preferred, and methyl 2-phenylisobutyrate, 2-phenylisobutyric acid, 2-isopropylhydroquinone, and 2-isopropyl-4-methoxyphenol are particularly preferred.

[0049] Component A1 may consist of one type or two or more types.

[0050] (Component B) The methacrylic acid-containing composition according to the first embodiment contains component B, which is a polymerization inhibitor. A polymerization inhibitor is a compound that has the function of suppressing the polymerization reaction of methacrylic acid. Examples of polymerization inhibitors include phenolic compounds, quinone compounds, nitrobenzene compounds, N-oxyl compounds, amine compounds, phosphorus-containing compounds, sulfur-containing compounds, iron-containing compounds, copper-containing compounds, and manganese-containing compounds. By containing component B, the polymerization reaction of methacrylic acid by the radical polymerization mechanism can be suppressed during storage of methacrylic acid. In addition, component B can trap the aforementioned hydroxyl radicals that are generated during storage of methacrylic acid. That is, when the methacrylic acid-containing composition contains component B in addition to component A1, the amount of hydroxyl radicals can be reduced by two different mechanisms: component A1 suppresses the generation of hydroxyl radicals, and component B removes the generated hydroxyl radicals. Therefore, it is considered that the decrease of component B and the generation of decomposition products can be efficiently suppressed.

[0051] Examples of polymerization inhibitors that are phenolic compounds include alkylphenols, hydroxyphenols, aminophenols, nitrophenols, nitrosophenols, alkoxyphenols, and tocopherols.

[0052] Examples of alkylphenols include o-cresol, m-cresol, p-cresol, 2-t-butyl-4-methylphenol, 2,4-dimethyl-6-t-butylphenol, 2,6-di-t-butyl-4-methylphenol, 2-t-butylphenol, 4-t-butylphenol, 2,4-di-t-butylphenol, 2-methyl-4-t-butylphenol, 4-t-butyl-2,6-dimethylphenol, 2,2'-methylenebis(6-t-butyl-4-methylphenol), 2,2'-methylenebis(4-ethyl-6-t-butylphenol), 4,4'-thiobis(3-methyl-6-t-butylphenol), and 3,5-di-t-butyl-4-hydroxytoluene.

[0053] Examples of hydroxyphenols include hydroquinone, 2-methylhydroquinone, 2-t-butylhydroquinone, 2,5-di-t-butylhydroquinone, 2,6-di-t-butylhydroquinone, 2,5-di-t-amylhydroquinone, 2-t-butylmethoxyhydroquinone, 2,3,5-trimethylhydroquinone, 2,5-dichlorohydroquinone, 1,2-dihydroxybenzene, 2-acetylhydroquinone, 4-methylcatechol, 4-t-butylcatechol, 2-methylresorcinol, 4-methylresorcinol, and 2,3-dihydroxyacetophenone.

[0054] Examples of aminophenols include o-aminophenol, m-aminophenol, p-aminophenol, 2-(N,N-dimethylamino)phenol, and 4-(ethylamino)phenol.

[0055] Examples of nitrophenols include o-nitrophenol, m-nitrophenol, p-nitrophenol, and 2,4-dinitrophenol. Examples of nitrosophenols include o-nitrosophenol, m-nitrosophenol, p-nitrosophenol, and α-nitroso-β-naphthol.

[0056] Examples of alkoxyphenols include 2-methoxyphenol, 2-ethoxyphenol, 2-isopropoxyphenol, 2-t-butoxyphenol, 4-methoxyphenol, 4-ethoxyphenol, 4-propoxyphenol, 4-butoxyphenol, 4-t-butoxyphenol, 4-heptoxyphenol, hydroquinone monobenzyl ether, t-butyl-4-methoxyphenol, di-t-butyl-4-methoxyphenol, pyrogallol-1,2-dimethyl ether, and hydroquinone monobenzoate.

[0057] Examples of tocopherols include α-tocopherol and 2,3-dihydro-2,2-dimethyl-7-hydroxybenzofuran.

[0058] Examples of polymerization inhibitors that are quinone compounds 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.

[0059] Examples of polymerization inhibitors that are nitrobenzene compounds include nitrobenzene, o-dinitrobenzene, m-dinitrobenzene, p-dinitrobenzene, 2,4-dinitrotoluene, dinitrojulene, and 2,2-diphenyl-1-picrylhydrazyl.

[0060] Examples of polymerization inhibitors that are N-oxyl compounds include 4-hydroxy-2,2,6,6-tetramethyl-piperidine-N-oxyl, 4-oxo-2,2,6,6-tetramethyl-piperidine-N-oxyl, 4-acetoxy-2,2,6,6-tetramethyl-piperidine-N-oxyl, 2,2,6,6-tetramethyl-piperidine-N-oxyl, piperidine-1-oxyl, 4-(dimethylamino)-2,2,6,6-tetramethyl-piperidine-N-oxyl, 4-amino-2,2,6,6-tetramethyl-piperidine-N-oxyl, 4-ethanoloxy-2,2,6,6-tetramethyl-piperidine-N-oxyl, and 4-benzoyloxy-2,2,6,6-tetramethylpiperidine-N-oxyl Examples include 2,2,5,5-tetramethyl-piperidine-N-oxyl, 3-amino-2,2,5,5-tetramethyl-piperidine-N-oxyl, 4,4',4''-tris(2,2,6,6-tetramethyl-piperidine-N-oxyl) phosphite, 3-oxo-2,2,5,5-tetramethylpyrrolidine-N-oxyl, pyrrolidine-1-oxyl, 2,2,5,5-tetramethyl-1-oxa-3-azacyclopentyl-3-oxy, 2,2,5,5-tetramethyl-3-pyrrolinyl-1-oxy-3-carboxylic acid, 2,2,3,3,5,5,6,6-octamethyl-1,4-diazacyclohexyl-1,4-dioxy, di-tert-butyl nitroxide, di-tert-amyl nitroxide, etc.

[0061] Examples of polymerization inhibitors that are amine compounds include N,N-diphenylamine, alkylated diphenylamine, 4,4'-dicumyl-diphenylamine, 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, and each group consists of 1 to 4 carbon atoms independently of each other, 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, Examples include N,N'-di-2-naphthyl-p-phenylenediamine, N,N-diethylhydroxylamine, 1,4-benzenediamine, N-(1,4-dimethylpentyl)-N'-phenyl-1,4-benzenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-1,4-benzenediamine, 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline, 2,2,4-trimethyl-1,2-dihydroquinoline polymer, aldol-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, and 1-hydroxy-4-benzoyloxy-2,2,6,6-tetramethylpiperidine.

[0062] Examples of polymerization inhibitors containing phosphorus include triphenylphosphine, triphenyl phosphite, triethyl phosphite, tris(isodecyl) phosphite, tris(tridecyl) phosphite, phenyldiisooctyl phosphite, phenyldiisodecyl phosphite, phenyldi(tridecyl) phosphite, diphenylisooctyl phosphite, diphenylisodecyl phosphite, diphenyltridecyl phosphite, phosphonic acid [1,1-diphenyl-4,4'-diylbistetrakis-2,4-bis(1,1-dimethylethyl)phenyl]ester, tris(nonylphenyl) phosphite, 4,4'-isopropylidenediphenolalkyl phosphite, tris(2,4-di-tert-butylphenyl) phosphite, tris(biphenyl) phosphite, and distearylpentaerythritol. Examples include di(2,4-di-tert-butylphenyl)pentaerythritol diphosphite, di(nonylphenyl)pentaerythritol diphosphite, phenylbisphenol A pentaerythritol diphosphite, tetra(tridecyl)-4,4'-butylidenebis(3-methyl-6-tert-butylphenol) diphosphite, hexa(tridecyl)-1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane triphosphite, 3,5-di-tert-butyl-4-hydroxybenzyl phosphate diethyl ester, sodium-bis(4-tert-butylphenyl) phosphate, sodium-2,2'-methylene-bis(4,6-di-tert-butylphenyl) phosphate, and 1,3-bis(diphenoxyphosphonyloxy)benzene.

[0063] Examples of polymerization inhibitors containing sulfur include diphenyl sulfide, phenothiazine, 3-oxofhenothiazine, 5-oxofhenothiazine, phenothiazine dimers, 1,4-dimercaptobenzene, 1,2-dimercaptobenzene, 2-mercaptophenol, 4-mercaptophenol, 2-(methylthio)phenol, 3,7-bis(dimethylamino)phenothiazinium chloride, and elemental sulfur.

[0064] Examples of polymerization inhibitors that contain iron include iron(III) chloride.

[0065] Examples of polymerization inhibitors containing copper include copper dimethyldithiocarbamate, copper diethyldithiocarbamate, copper dibutyldithiocarbamate, copper salicylate, copper acetate, copper thiocyanate, copper nitrate, copper chloride, copper carbonate, copper hydroxide, copper acrylate, and copper methacrylate.

[0066] Examples of manganese-containing polymerization inhibitors include manganese dialkyldithiocarbamate (the alkyl group is one of methyl, ethyl, propyl, or butyl groups, and may be the same or different), manganese diphenyldithiocarbamate, manganese formate, manganese acetate, manganese octanoate, manganese naphthenate, manganese permanganate, and manganese salts of ethylenediaminetetraacetic acid.

[0067] Among the above, from the viewpoint of quality stability during storage of the methacrylic acid-containing composition, component B is preferably at least one polymerization inhibitor selected from the group consisting of phenolic compounds, N-oxyl compounds, amine compounds, phosphorus-containing compounds, and sulfur-containing compounds. For example, it is preferably at least one polymerization inhibitor selected from the group consisting of hydroquinone, 4-methoxyphenol, 2,4-dimethyl-6-t-butylphenol, 2,6-di-t-butyl-4-methylphenol, 4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl, N,N-diphenylamine, N-nitrosodiphenylamine, triphenyl phosphite, and phenothiazine. Component B is more preferably a phenolic compound, for example at least one polymerization inhibitor selected from the group consisting of hydroquinone, 4-methoxyphenol, 2,4-dimethyl-6-t-butylphenol, and 2,6-di-t-butyl-4-methylphenol. Component B is more preferably at least one polymerization inhibitor selected from the group consisting of, for example, hydroquinone, 4-methoxyphenol, and 2,6-di-t-butyl-4-methylphenol. Component B is particularly preferably at least one polymerization inhibitor selected from the group consisting of, for example, hydroquinone and 4-methoxyphenol.

[0068] Component B may be one type or two or more types. If two or more types of component B are present, the total amount shall be considered the content of component B. If a methacrylic acid-containing composition contains a compound that corresponds to both component A1 and component B, that compound shall be considered as component B. In other words, the methacrylic acid-containing composition must contain a component A1 other than that compound. If two or more compounds that correspond to both component A1 and component B are contained, the compound with the highest molar concentration in the methacrylic acid-containing composition shall be considered as component B, and the other compounds shall be considered as component A1.

[0069] (Concentrations of component A1 and component B) The concentration of component A1 is M A1 (μmol / L), the concentration of component B is MB When expressed as (μmol / L), from the viewpoint of efficiency in suppressing the consumption of polymerization inhibitors, M B / M A1 The value is preferably 0.0005 to 100, more preferably 0.001 to 85, even more preferably 0.005 to 70, and particularly preferably 0.005 to 60.

[0070] M A1 The concentration is preferably 1 to 500,000 μmol / L. A1 When the concentration is 1 μmol / L or higher, the effect of suppressing the consumption of polymerization inhibitors can be sufficiently obtained. A1 By having a concentration of 500,000 μmol / L or less, the amount of impurities produced when a methacrylic acid polymer is manufactured by polymerization of the methacrylic acid-containing composition according to the first embodiment can be reduced, thereby preventing adverse effects on the physical properties of the polymer. A1 The lower limit is more preferably 10 μmol / L or higher, even more preferably 30 μmol / L or higher, even more preferably 50 μmol / L or higher, and particularly preferably 70 μmol / L or higher. A1 The upper limit is more preferably 450,000 μmol / L or less, even more preferably 400,000 μmol / L or less, particularly preferably 350,000 μmol / L or less, and especially preferably 300,000 μmol / L or less.

[0071] M B The concentration is preferably 1 to 50,000 μmol / L. B When the concentration is 1 μmol / L or higher, the effect of suppressing the consumption of polymerization inhibitors can be sufficiently obtained. B By having a concentration of 50,000 μmol / L or less, the amount of impurities produced when a methacrylic acid polymer is manufactured by polymerization of the methacrylic acid-containing composition according to the first embodiment can be reduced, thereby preventing adverse effects on the physical properties of the polymer. B The lower limit is more preferably 10 μmol / L or higher, even more preferably 100 μmol / L or higher, particularly preferably 1000 μmol / L or higher, and especially preferably 2000 μmol / L or higher. BThe upper limit is more preferably 40,000 μmol / L or less, even more preferably 30,000 μmol / L or less, and particularly preferably 25,000 μmol / L or less.

[0072] (Concentration of methacrylic acid) The concentration of methacrylic acid in the methacrylic acid-containing composition according to the first embodiment is 98.00 to 99.99% by mass. By having a methacrylic acid concentration of 98.00% by mass or higher, the amount of impurities produced when a methacrylic acid polymer is manufactured by polymerization of the methacrylic acid-containing composition according to the first embodiment can be reduced, and adverse effects on the physical properties of the polymer can be prevented. Furthermore, by having a methacrylic acid concentration of 99.99% by mass or lower, purification costs can be reduced. The lower limit of the methacrylic acid concentration is more preferably 98.50% or higher, even more preferably 99.00% or higher, particularly preferably 99.50% or higher, and most preferably 99.80% by mass or higher.

[0073] (Component C) The methacrylic acid-containing composition according to the first embodiment may further contain component C, which is another compound, as long as the concentration of methacrylic acid satisfies 98.00 to 99.99% by mass. Component C may include impurities generated during the production of methacrylic acid. For example, methacrylic acid may contain diacetyl as an impurity, but 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, even more preferably 10 μmol / L or less, and particularly preferably 1 μmol / L or less.

[0074] (Analysis of methacrylic acid-containing compositions) The presence of component A1, component B, component C, and water in a methacrylic acid-containing composition can be confirmed, for example, by GC-MS measurement. If the GC-MS chart of the methacrylic acid-containing composition shows a peak at the same retention time as the standard of component A1, and the m / z value detected in the mass spectrum of that peak matches the exact mass of component A1, then it can be determined that the methacrylic acid-containing composition contains component A1. If a standard of component A1 is not available, the peak can be determined to be component A1 if the mass spectrum pattern of the peak appearing in the GC-MS chart of the methacrylic acid-containing composition matches the mass spectrum pattern of component A1 recorded in a mass spectrum database. In other words, it can be determined that the methacrylic acid-containing composition contains component A1. Examples of mass spectrum databases include NIST20, NIST17, NIST14, and NIST14s. Furthermore, if the volatility is low and detection by GC-MS measurement is not possible, detection can be performed using LC-MS. The presence of component B, component C, and water can also be confirmed by a similar method. Furthermore, the concentration of methacrylic acid can be calculated, for example, by performing a GC-FID measurement of the methacrylic acid-containing composition, quantifying it using the area percentage method, and correcting it using the moisture concentration quantified with a Karl Fischer moisture meter. The concentration of component A1 can be calculated, for example, by performing a GC measurement of the methacrylic acid-containing composition and quantifying it using the internal standard method. If a standard sample of component A1 cannot be obtained and quantification cannot be performed by the internal standard method, the concentration of component A1 can be calculated using the following formula by performing a GC-FID measurement of any organic compound with a known concentration under the same conditions as the methacrylic acid-containing composition.

[0075]

number

[0076] 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 A1is the peak area of ​​component A1, S is the peak area of ​​the organic compound with a known concentration, and M is the concentration (μmol / L) of the organic compound with a known concentration.

[0077] If the volatility is low and quantification by GC measurement is not possible, quantification can be performed using chromatographic methods such as LC. The concentrations of components B and C can also be calculated using the same method as for component A1 described above. Furthermore, the presence of water in the methacrylic acid-containing composition, and its concentration, can be confirmed by the Karl Fischer method.

[0078] [Methacrylic acid-containing composition production method] A method for producing a methacrylic acid-containing composition according to the first embodiment includes adding component A1 and component B to methacrylic acid. The methacrylic acid may be a commercially available product, or methacrylic acid produced by known methods such as the acetone cyanohydrin (ACH) method or the C4 direct oxidation method may be used. Components A1 and B may be commercially available products, or synthesized by known methods. When using a commercially available product containing component B as methacrylic acid, component B contained in the commercially available product may be used as component B of the present invention, or component B may be added in addition. When using methacrylic acid produced by known methods such as the acetone cyanohydrin (ACH) method or the C4 direct oxidation method, component A1 or component B may be added as a raw material or during the manufacturing process to produce the methacrylic acid-containing composition. Furthermore, if component A1 or component B is produced as a by-product in the methacrylic acid manufacturing process, the methacrylic acid-containing composition may be produced by leaving a portion of the produced component A1 or component B.

[0079] [Methods for evaluating storage stability and thermal stability] The methacrylic acid-containing composition according to the first embodiment exhibits high quality stability during storage. Methods for evaluating the quality stability of the methacrylic acid-containing composition during storage include, for example, actually storing the methacrylic acid-containing composition for a long period and confirming the decrease in polymerization inhibitor. Alternatively, from the viewpoint of ease of operation, a method of heating the methacrylic acid-containing composition for a short time and confirming the decrease in polymerization inhibitor may 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 this invention, the quality stability of the methacrylic acid-containing composition during storage was evaluated by the decrease in polymerization inhibitor when the methacrylic acid-containing composition was stored at 25°C for 21 days.

[0080] [Methacrylic acid ester production method according to the first embodiment] The method for producing a methacrylic acid ester according to the first embodiment includes a step of esterifying the methacrylic acid in the methacrylic acid-containing composition according to the first embodiment. The alcohol reacted with the methacrylic acid-containing composition is not particularly limited and includes, for example, methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, etc. The resulting methacrylic acid esters include, for example, methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, butyl methacrylate, isobutyl methacrylate, etc. The esterification reaction can be carried out in the presence of an acidic catalyst such as a sulfonic acid type cation exchange resin. The temperature during the esterification reaction is preferably 50 to 200°C. The pressure during the esterification reaction, the position of the catalyst in the reactor, and the proportion of the catalyst in the reactor are not particularly limited, and commonly used configurations can be applied.

[0081] [Methacrylic acid polymer production method according to the first embodiment] A method for producing a methacrylic acid polymer according to the first embodiment includes a step of polymerizing a polymerizable composition containing the methacrylic acid-containing composition according to the first embodiment.

[0082] The polymerizable composition may further contain monomers copolymerizable with methacrylic acid and other additives, as needed.

[0083] Examples of monomers copolymerizable with methacrylic acid include the following: Methacrylic acid esters such as methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, iso-butyl methacrylate, tert-butyl methacrylate, 2-ethylhexyl methacrylate, phenyl methacrylate, or benzyl methacrylate; Acrylic acid esters such as methyl acrylate, ethyl acrylate, n-butyl acrylate, iso-butyl acrylate, tert-butyl acrylate, or 2-ethylhexyl acrylate; Unsaturated carboxylic acids such as acrylic acid, maleic acid, or itaconic acid; Unsaturated carboxylic acid anhydrides such as maleic anhydride or itaconic anhydride; Maleimides such as N-phenylmaleimide or N-cyclohexylmaleimide; 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, or 2-hydroxypropyl methacrylate, or other hydroxyl group-containing vinyl monomers; Vinyl esters such as vinyl acetate or vinyl benzoate; Vinyl chloride, vinylidene chloride, and their derivatives; Nitrogen-containing vinyl monomers such as methacrylamide or acrylonitrile; Epoxy group-containing monomers such as glycidyl acrylate or glycidyl methacrylate; Aromatic vinyl monomers such as styrene or α-methylstyrene; Alkane diol 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; 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; Vinyl monomers having two or more ethylenically unsaturated bonds in their molecules, such as divinylbenzene; Unsaturated polyester prepolymer obtained from at least one polycarboxylic acid containing an ethylenically unsaturated polycarboxylic acid and at least one diol; A vinyl ester prepolymer obtained by modifying the ends of epoxy groups with acrylic.

[0084] Among the above, the monomer copolymerizable with methacrylic acid is preferably at least one selected from the group consisting of methacrylic acid esters and acrylic acid esters. The monomer copolymerizable with methacrylic acid is more preferably a methacrylic acid ester, and particularly preferably methyl methacrylate.

[0085] The monomer copolymerizable with methacrylic acid may be one type or two or more types. Furthermore, if component A1 is a monomer copolymerizable with methacrylic acid, component A1 may be used as the monomer copolymerizable with methacrylic acid, or a monomer copolymerizable with methacrylic acid may be used separately from component A1.

[0086] In the polymerizable composition, the content of monomers copolymerizable with methacrylic acid is preferably 50.00 to 99.99 parts by mass per 100 parts by mass of the polymerizable composition. The lower limit of the content of monomers copolymerizable with methacrylic acid is more preferably 60 parts by mass or more, even more preferably 70 parts by mass or more, particularly preferably 80 parts by mass or more, and most preferably 90 parts by mass or more, per 100 parts by mass of the polymerizable composition. The upper limit of the content of monomers copolymerizable with methacrylic acid is more preferably 99.9 parts by mass or less, and even more preferably 99 parts by mass or less, per 100 parts by mass of the polymerizable composition.

[0087] Other additives include, for example, polymerization initiators, chain transfer agents, mold release agents, lubricants, plasticizers, antioxidants, antistatic agents, light stabilizers, UV absorbers, flame retardants, flame retardant aids, polymerization inhibitors, fillers, pigments, dyes, silane coupling agents, leveling agents, defoamers, and fluorescent agents. These other additives may be one type or two or more types.

[0088] Other additives that are preferred include polymerization initiators. Examples of polymerization initiators include the following: 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(cyclohexanecarbonitride), and dimethyl-2,2'-azobisisobutyrate; Benzoyl peroxide, 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane, 1,1-bis(t-butylperoxy)cyclohexane, 1,1-bis(t-butylperoxy)-3,5,5-trimethylcyclohexane, t-butylperoxy-2-ethylhexanoate, t-butylperoxyisobutyrate, t-butylperoxybenzoate, t-hexylperoxybenzoate, t-butylperoxyisopropyl monocarbonate, t-butylperoxy-3,5,5-trimethylhexanoate, t-butylperoxylaurate, t-butylperoxyacetate, t-hexylperoxyisopropyl monocarbonate, t-hexyl peroxy Organic peroxides such as -oxy-2-ethylhexanoate, t-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 peroxyisononate, 1,1,2-trimethylpropyl peroxyisononate, di-t-butyl peroxide, di-t-hexyl peroxide, lauroyl peroxide, and dilauroyl peroxide; Persulfate compounds such as potassium persulfate; A redox polymerization initiator.

[0089] Among the above, from the viewpoint of storage stability and reactivity with methacrylic acid and copolymerizable monomers, the polymerization initiator is preferably at least one selected from the group consisting of azo compounds and organic peroxides. The amount of polymerization initiator used is preferably 0.0001 to 1 part by mass per 100 parts by mass of methacrylic acid and monomers copolymerizable with methacrylic acid.

[0090] Polymerization methods for polymerizable compositions include, for example, bulk polymerization, solution polymerization, emulsion polymerization, and suspension polymerization. The polymerization temperature is preferably 125 to 210°C. This allows for obtaining an appropriate polymerization rate. The lower limit of the polymerization temperature is more preferably 130°C or higher, and the upper limit is more preferably 180°C or lower. The polymerization time is not particularly limited and can be, for example, 0.5 to 24 hours.

[0091] [Methacrylic acid-containing composition according to the second embodiment] 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.

[0092] [ka]

[0093] In formula (21), R 1b , R 2b , R 3b and R 4b Each of these independently represents a hydrogen atom, an alkyl group, an alkenyl group, an aryl group, a hydroxyl group, an alkoxy group, an amino group, a carbonyl group (all monovalent), an alkylthio group, or an arylthio group. 1b and R 2b , R 3b and R 4b These may be connected to each other to form a ring. Furthermore, the methacrylic acid-containing composition may also contain other compounds (component C) or water, as long as the concentration of methacrylic acid satisfies 98.00 to 99.99% by mass. Each item will be explained in detail below.

[0094] (Methacrylic acid) The methacrylic acid-containing composition according to the second embodiment contains methacrylic acid. Methacrylic acid can be produced, for example, as a by-product of the acetone cyanohydrin (ACH) process or as an intermediate of the C4 direct oxidation process. The methacrylic acid contained in the methacrylic acid-containing composition is preferably produced by the C4 direct oxidation process, and more preferably produced by the C4 direct oxidation process using biomass-derived isobutanol as a starting material.

[0095] (Ingredient A21) The first embodiment of the methacrylic acid-containing composition according to the second aspect contains component A21, which is a compound represented by formula (21). 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.

[0096] Methacrylic acid is known to polymerize due to radicals generated during storage, and a polymerization inhibitor (component B) is added to prevent polymerization. Component B has a polymerization inhibitory function by trapping radicals generated during the storage of methacrylic acid, but because the polymerization inhibitor decomposes into other compounds when trapping radicals, the concentration of component B in the methacrylic acid-containing composition gradually decreases during storage, and the polymerization inhibitory function gradually deteriorates. Furthermore, the amount of unwanted decomposition products generated by component B trapping radicals gradually increases. An example of a radical generated during the storage of methacrylic acid is the hydroxyl radical, which is generated when oxygen molecules absorb ultraviolet light from sunlight. Component A21 has an aromatic ring and therefore absorbs ultraviolet light, and its absorption wavelength changes depending on the type of substituent. Component A21, having the structure represented by formula (21), can absorb ultraviolet light of a wide range of wavelengths. Therefore, by containing component A21 in the methacrylic acid-containing composition, ultraviolet light of a wide range of wavelengths is absorbed, and the generation of hydroxyl radicals due to oxygen molecules absorbing ultraviolet light is suppressed. Therefore, since the number of radicals that component B needs to trap is reduced, the decrease in the concentration of component B and the generation of degradation products can be suppressed.

[0097] The molecular weight of component A21 is preferably 1000 or less. This increases the number of pyrazine rings per unit mass of component A21, so that the effects 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, even more preferably 600 or less, and particularly preferably 400 or less.

[0098] In equation (21) above, R 1b , R 2b , R 3b and R 4b Each of these independently represents a hydrogen atom, an alkyl group, an alkenyl group, an aryl group, a hydroxyl group, an alkoxy group, an amino group, a carbonyl group (monovalent group), an alkylthio group, or an arylthio group. 1b , R 2b , R 3b and R 4b They may be the same or different.

[0099] From the perspective of increasing the absorbance of ultraviolet light and suppressing the generation of hydroxyl radicals, R 1b , R 2b , R 3b and R 4b It is preferably a hydrogen atom, a C1-C5 alkyl group, a C2-C5 alkenyl group, a C6-C2 aryl group, a C1-C6 alkoxy group, a C0-C6 amino group, a C1-C6 carbonyl group, a C1-C5 alkylthio group, or a C6-C10 arylthio group; more preferably a hydrogen atom, a C1-C5 alkyl group, a C1-C6 alkoxy group, a C1-C6 carbonyl group, or a C6-C10 alkylthio group; even more preferably a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, a methylthio group, a methoxy group, a carboxyl group, a carbomethoxy group, or a hydroxymethyl group; and particularly preferably a hydrogen atom, a methyl group, an isopropyl group, a methylthio group, a methoxy group, a carboxyl group, a carbomethoxy group, or a hydroxymethyl group.

[0100] The alkyl group is a linear (linear or branched) alkyl group or a cyclic alkyl group. Alkyl groups having 1 to 20 carbon atoms are preferred, alkyl groups having 1 to 10 carbon atoms are more preferred, and alkyl groups having 1 to 5 carbon atoms are even more preferred. Examples of linear alkyl groups include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, s-butyl group, t-butyl group, n-pentyl group, isopentyl group, hexyl group, octyl group, decyl group, hydroxymethyl group, 1-hydroxyethyl group, and 2-hydroxyethyl group, with methyl group, ethyl group, n-propyl group, and isopropyl group being preferred. Examples of cyclic alkyl groups include cyclopentyl group, cyclohexyl group, and cyclooctyl group.

[0101] The alkenyl group is a linear (linear or branched) alkenyl group or a cyclic alkenyl group. Alkenyl groups with 2 to 20 carbon atoms are preferred, alkenyl groups with 2 to 10 carbon atoms are more preferred, and alkenyl groups with 2 to 5 carbon atoms are even more preferred. Examples of linear alkenyl groups include vinyl, 1-propenyl, isopropenyl, 2-butenyl, 1,3-butadienyl, 2-pentenyl, and 2-hexenyl groups. Examples of cyclic alkenyl groups include cyclopentenyl and cyclohexenyl groups.

[0102] 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 heteroaryl groups containing oxygen, nitrogen, sulfur, etc. Examples of aryl groups include phenyl, mesityl, naphthyl, 2-methylphenyl, 3-methylphenyl, 4-methylphenyl, 2,3-dimethylphenyl, 2,4-dimethylphenyl, 2,5-dimethylphenyl, 2,6-dimethylphenyl, 2-ethylphenyl, isoxazolyl, isothiazolyl, imidazolyl, oxazolyl, thiazolyl, thiadiazolyl, thienyl, triazolyl, tetrazolyl, pyridyl, pyrazinyl, pyrimidinyl, pyridadinyl, pyrazolyl, pyrrolyl, furyl, fluzanyl, isoquinolyl, isoindolyl, indolyl, quinolyl, pyridothiazolyl, benzimidazolyl, benzoxazolyl, benzothiazolyl, benzotriazolyl, benzofuranyl, imidazopyridinyl, triazopyridinyl, and prinyl groups.

[0103] 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, even more preferably an alkoxy group having 1 to 6 carbon atoms, and particularly preferably an alkoxy group having 1 to 5 carbon atoms. Examples of alkoxy groups include methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, s-butoxy, t-butoxy, n-pentoxy, isopentoxy, and phenoxy groups.

[0104] The amino group includes an amino group (-NH2) (0 carbon atoms) with no substituents on the nitrogen atom, and an amino group in which some or all of the hydrogen atoms bonded to the nitrogen atom are substituted with carbon atoms. The number of carbon atoms in the amino group in which some 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 even more preferably 1 to 6. Examples of amino groups include an unsubstituted amino group (-NH2), methylamino group, ethylamino group, propylamino group, butylamino group, dimethylamino group, diethylamino group, anilino group, toluidino group, anisidino group, diphenylamino group, and N-methyl-N-phenylamino group.

[0105] Examples of monovalent groups containing a carbonyl group include formyl group, acyl group, carboxyl group, amide group, alkoxycarbonyl group, thiocarboxyl group, thioester group, etc., with monovalent groups containing a carbonyl group having 1 to 6 carbon atoms being preferred.

[0106] An acyl group is a substituent formed by linking a carbonyl group with an alkyl group, alkenyl group, or aryl group. The total number of carbon atoms derived from the carbonyl group (1) and the alkyl group, alkenyl group, or aryl group of the acyl group is preferably 2 to 20, more preferably 2 to 10, and even more preferably 2 to 6. Examples of acyl groups include acetyl group, propionyl group, butylcarbonyl group, vinylcarbonyl group, and benzoyl group.

[0107] The amide group includes an amide group (-CONH2) without substituents on the nitrogen atom, and an amide group in which some or all of the hydrogen atoms bonded to the nitrogen atom are substituted with carbon atoms. The total number of carbon atoms in the amide group is the sum of the carbon atoms derived from the carbonyl group (1) and the carbon atoms substituted on the nitrogen atom, which is preferably 1 to 20, more preferably 1 to 10, and even more preferably 1 to 5. Examples of amide groups include unsubstituted amide groups, N-methylamide groups, N-ethylamide groups, N-phenylamide groups, N,N-dimethylamide groups, and N-methyl-N-phenylamide groups.

[0108] An alkoxycarbonyl group is a substituent formed by linking a carbonyl group and an alkoxy group, and is also called an ester group. The total number of carbon atoms from the carbonyl group (1) and the alkoxy group is preferably 2 to 20, more preferably 2 to 10, and even more preferably 2 to 6. Examples of alkoxycarbonyl groups include methoxycarbonyl group, ethoxycarbonyl group, butoxycarbonyl group, and phenoxycarbonyl group.

[0109] A thioester group is a substituent formed by linking a carbonyl group with an alkylthio or arylthio group. The total number of carbon atoms derived from the carbonyl group (1) and the alkylthio or arylthio group is preferably 2 to 20, more preferably 2 to 10, and even more preferably 2 to 6. Examples of thioester groups include methylthiocarbonyl group, ethylthiocarbonyl group, butylthiocarbonyl group, and phenylthiocarbonyl group.

[0110] Furthermore, the monovalent group containing a carbonyl group may be a substituent in which one or more hydrogen atoms of an alkyl group are substituted with a carbonyl group. Examples of such substituents include 2-acetoxyethyl group, 2-acetoethyl group, and 2-(acetoacetoxy)ethyl group.

[0111] 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 even more preferably an alkylthio group having 1 to 5 carbon atoms. Examples of alkylthio groups include methylthio group, ethylthio group, propylthio group, isopropylthio group, and the like.

[0112] 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 even more preferably an arylthio group having 6 to 10 carbon atoms. Examples of arylthio groups include phenylthio groups and tolylthio groups.

[0113] Among the compounds that satisfy the above conditions, from the viewpoint of quality stability during storage of methacrylic acid-containing compositions, component A21 is selected as follows: 2,3,5,6-tetramethylpyrazine, pyrazine, 2,3,5-trimethylpyrazine, 2-methoxypyrazine, 2-isopropyl-3-methoxypyrazine, 2,5-dimethylpyrazine, 2-aminopyrazine, 2-methylpyrazinecarboxylate, 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-phenylpyrazine, 5,6,7,8-tetramethylpyrazine Lahydroquinoxaline, phenazine, or 1,2,3,4,6,7,8,9-octahydrophanazine is preferred, 2,3,5,6-tetramethylpyrazine, pyrazine, 2,3,5-trimethylpyrazine, 2-methoxypyrazine, 2-isopropyl-3-methoxypyrazine, 2,5-dimethylpyrazine, 2-aminopyrazine, 2-methylpyrazinecarboxylate, 2-(methylthio)pyrazine, 2-pyrazinemethanol, quinoxaline, or 2-vinylpyrazine is more preferred, and 2,3,5,6-tetramethylpyrazine, pyrazine, 2,3,5-trimethylpyrazine, 2-methoxypyrazine, 2-isopropyl-3-methoxypyrazine, 2,5-dimethylpyrazine, 2-pyrazinecarboxylate, 2-(methylthio)pyrazine, or 2-pyrazinemethanol is even more preferred.

[0114] Component A21 may be one type or two or more types.

[0115] (Component B) In the first embodiment of the second aspect, the methacrylic acid-containing composition contains component B. Component B is a compound that acts as a polymerization inhibitor. In this specification, a polymerization inhibitor means a compound that has the function of suppressing the polymerization reaction of methacrylic acid. Examples of polymerization inhibitors include phenolic compounds, quinone compounds, nitrobenzene compounds, N-oxyl compounds, amine compounds, phosphorus-containing compounds, sulfur-containing compounds, iron-containing compounds, copper-containing compounds, and manganese-containing compounds. By containing component B, the polymerization reaction of methacrylic acid by the radical polymerization mechanism can be suppressed during storage of methacrylic acid. In addition, component B can trap the aforementioned hydroxyl radicals that are generated during the storage of methacrylic acid. That is, when the methacrylic acid-containing composition contains component B in addition to component A21, the amount of hydroxyl radicals can be reduced by two different mechanisms: component A21 suppresses the generation of hydroxyl radicals, and component B removes the generated hydroxyl radicals. Therefore, it is considered that the decrease of component B can be efficiently suppressed.

[0116] Examples of polymerization inhibitors that are phenolic compounds include alkylphenols, hydroxyphenols, aminophenols, nitrophenols, nitrosophenols, alkoxyphenols, and tocopherols.

[0117] Examples of alkylphenols include o-cresol, m-cresol, p-cresol, 2-t-butyl-4-methylphenol, 2,4-dimethyl-6-t-butylphenol, 2,6-di-t-butyl-4-methylphenol, 2-t-butylphenol, 4-t-butylphenol, 2,4-di-t-butylphenol, 2-methyl-4-t-butylphenol, 4-t-butyl-2,6-dimethylphenol, 2,2'-methylenebis(6-t-butyl-4-methylphenol), 2,2'-methylenebis(4-ethyl-6-t-butylphenol), 4,4'-thiobis(3-methyl-6-t-butylphenol), and 3,5-di-t-butyl-4-hydroxytoluene.

[0118] Examples of hydroxyphenols include hydroquinone, 2-methylhydroquinone, 2-t-butylhydroquinone, 2,5-di-t-butylhydroquinone, 2,6-di-t-butylhydroquinone, 2,5-di-t-amylhydroquinone, 2-t-butylmethoxyhydroquinone, 2,3,5-trimethylhydroquinone, 2,5-dichlorohydroquinone, 1,2-dihydroxybenzene, 2-acetylhydroquinone, 4-methylcatechol, 4-t-butylcatechol, 2-methylresorcinol, 4-methylresorcinol, and 2,3-dihydroxyacetophenone.

[0119] Examples of aminophenols include o-aminophenol, m-aminophenol, p-aminophenol, 2-(N,N-dimethylamino)phenol, and 4-(ethylamino)phenol.

[0120] Examples of nitrophenols include o-nitrophenol, m-nitrophenol, p-nitrophenol, and 2,4-dinitrophenol. Examples of nitrosophenols include o-nitrosophenol, m-nitrosophenol, p-nitrosophenol, and α-nitroso-β-naphthol.

[0121] Examples of alkoxyphenols include 2-methoxyphenol, 2-ethoxyphenol, 2-isopropoxyphenol, 2-t-butoxyphenol, 4-methoxyphenol, 4-ethoxyphenol, 4-propoxyphenol, 4-butoxyphenol, 4-t-butoxyphenol, 4-heptoxyphenol, hydroquinone monobenzyl ether, t-butyl-4-methoxyphenol, di-t-butyl-4-methoxyphenol, pyrogallol-1,2-dimethyl ether, and hydroquinone monobenzoate.

[0122] Examples of tocopherols include α-tocopherol and 2,3-dihydro-2,2-dimethyl-7-hydroxybenzofuran.

[0123] Examples of polymerization inhibitors that are quinone compounds 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.

[0124] Examples of polymerization inhibitors that are nitrobenzene compounds include nitrobenzene, o-dinitrobenzene, m-dinitrobenzene, p-dinitrobenzene, 2,4-dinitrotoluene, dinitrojulene, and 2,2-diphenyl-1-picrylhydrazyl.

[0125] Examples of polymerization inhibitors that are N-oxyl compounds include 4-hydroxy-2,2,6,6-tetramethyl-piperidine-N-oxyl, 4-oxo-2,2,6,6-tetramethyl-piperidine-N-oxyl, 4-acetoxy-2,2,6,6-tetramethyl-piperidine-N-oxyl, 2,2,6,6-tetramethyl-piperidine-N-oxyl, piperidine-1-oxyl, 4-(dimethylamino)-2,2,6,6-tetramethyl-piperidine-N-oxyl, 4-amino-2,2,6,6-tetramethyl-piperidine-N-oxyl, 4-ethanoloxy-2,2,6,6-tetramethyl-piperidine-N-oxyl, and 4-benzoyloxy-2,2,6,6-tetramethylpiperidine-N-oxyl Examples include 2,2,5,5-tetramethyl-piperidine-N-oxyl, 3-amino-2,2,5,5-tetramethyl-piperidine-N-oxyl, 4,4',4''-tris(2,2,6,6-tetramethyl-piperidine-N-oxyl) phosphite, 3-oxo-2,2,5,5-tetramethylpyrrolidine-N-oxyl, pyrrolidine-1-oxyl, 2,2,5,5-tetramethyl-1-oxa-3-azacyclopentyl-3-oxy, 2,2,5,5-tetramethyl-3-pyrrolinyl-1-oxy-3-carboxylic acid, 2,2,3,3,5,5,6,6-octamethyl-1,4-diazacyclohexyl-1,4-dioxy, di-tert-butyl nitroxide, di-tert-amyl nitroxide, etc.

[0126] Examples of polymerization inhibitors that are amine compounds include N,N-diphenylamine, alkylated diphenylamine, 4,4'-dicumyl-diphenylamine, 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, and each group consists of 1 to 4 carbon atoms independently of each other, 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, Examples include N,N'-di-2-naphthyl-p-phenylenediamine, N,N-diethylhydroxylamine, 1,4-benzenediamine, N-(1,4-dimethylpentyl)-N'-phenyl-1,4-benzenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-1,4-benzenediamine, 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline, 2,2,4-trimethyl-1,2-dihydroquinoline polymer, aldol-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, and 1-hydroxy-4-benzoyloxy-2,2,6,6-tetramethylpiperidine.

[0127] Examples of polymerization inhibitors containing phosphorus include triphenylphosphine, triphenyl phosphite, triethyl phosphite, tris(isodecyl) phosphite, tris(tridecyl) phosphite, phenyldiisooctyl phosphite, phenyldiisodecyl phosphite, phenyldi(tridecyl) phosphite, diphenylisooctyl phosphite, diphenylisodecyl phosphite, diphenyltridecyl phosphite, phosphonic acid [1,1-diphenyl-4,4'-diylbistetrakis-2,4-bis(1,1-dimethylethyl)phenyl]ester, tris(nonylphenyl) phosphite, 4,4'-isopropylidenediphenolalkyl phosphite, tris(2,4-di-tert-butylphenyl) phosphite, tris(biphenyl) phosphite, and distearylpentaerythritol. Examples include di(2,4-di-tert-butylphenyl)pentaerythritol diphosphite, di(nonylphenyl)pentaerythritol diphosphite, phenylbisphenol A pentaerythritol diphosphite, tetra(tridecyl)-4,4'-butylidenebis(3-methyl-6-tert-butylphenol) diphosphite, hexa(tridecyl)-1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane triphosphite, 3,5-di-tert-butyl-4-hydroxybenzyl phosphate diethyl ester, sodium-bis(4-tert-butylphenyl) phosphate, sodium-2,2'-methylene-bis(4,6-di-tert-butylphenyl) phosphate, and 1,3-bis(diphenoxyphosphonyloxy)benzene.

[0128] Examples of polymerization inhibitors containing sulfur include diphenyl sulfide, phenothiazine, 3-oxofhenothiazine, 5-oxofhenothiazine, phenothiazine dimers, 1,4-dimercaptobenzene, 1,2-dimercaptobenzene, 2-mercaptophenol, 4-mercaptophenol, 2-(methylthio)phenol, 3,7-bis(dimethylamino)phenothiazinium chloride, and elemental sulfur.

[0129] Examples of polymerization inhibitors that contain iron include iron(III) chloride.

[0130] Examples of polymerization inhibitors containing copper include copper dimethyldithiocarbamate, copper diethyldithiocarbamate, copper dibutyldithiocarbamate, copper salicylate, copper acetate, copper thiocyanate, copper nitrate, copper chloride, copper carbonate, copper hydroxide, copper acrylate, and copper methacrylate.

[0131] Examples of manganese-containing polymerization inhibitors include manganese dialkyldithiocarbamate (the alkyl group is one of methyl, ethyl, propyl, or butyl groups, and may be the same or different), manganese diphenyldithiocarbamate, manganese formate, manganese acetate, manganese octanoate, manganese naphthenate, manganese permanganate, and manganese salts of ethylenediaminetetraacetic acid.

[0132] Among the above, from the viewpoint of quality stability during storage of the methacrylic acid-containing composition, component B is preferably at least one polymerization inhibitor selected from the group consisting of phenolic compounds, N-oxyl compounds, amine compounds, phosphorus-containing compounds, and sulfur-containing compounds. For example, it is preferably at least one polymerization inhibitor selected from the group consisting of hydroquinone, 4-methoxyphenol, 2,4-dimethyl-6-t-butylphenol, 2,6-di-t-butyl-4-methylphenol, 4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl, N,N-diphenylamine, N-nitrosodiphenylamine, triphenyl phosphite, and phenothiazine. Component B is more preferably a phenolic compound, for example at least one polymerization inhibitor selected from the group consisting of hydroquinone, 4-methoxyphenol, 2,4-dimethyl-6-t-butylphenol, and 2,6-di-t-butyl-4-methylphenol. Component B is more preferably a phenolic compound, and even more preferably at least one polymerization inhibitor selected from the group consisting of, for example, hydroquinone and 4-methoxyphenol.

[0133] Component B may be one type or two or more types. If a methacrylic acid-containing composition contains a compound that corresponds to both component A21 and component B, that compound shall be considered as component B. In other words, the methacrylic acid-containing composition must contain a component A21 that is different from that compound. If two or more compounds that correspond to both component A21 and component B are contained, the compound with the highest molar concentration in the methacrylic acid-containing composition shall be considered as component B, and the other compounds shall be considered as component A21.

[0134] (Concentrations of components A21 and B) The concentration of component A21 is M A21 (μmol / L), the concentration of component B is M B When expressed as (μmol / L), from the viewpoint of inhibiting pyruvate production, M B / M A21The value is preferably 0.005 to 100, more preferably 0.01 to 80, even more preferably 0.05 to 60, and particularly preferably 0.1 to 40.

[0135] M A21 The concentration is preferably 1 to 50,000 μmol / L. A21 When the concentration is 1 μmol / L or higher, the effect of suppressing the decomposition of polymerization inhibitors can be sufficiently obtained. A21 By having a concentration of 50,000 μmol / L or less, the amount of impurities produced when a methacrylic acid polymer is manufactured by polymerization of the methacrylic acid-containing composition according to the second embodiment can be reduced, thereby preventing adverse effects on the physical properties of the polymer. A21 The lower limit is more preferably 10 μmol / L or higher, even more preferably 30 μmol / L or higher, particularly preferably 50 μmol / L or higher, and especially preferably 60 μmol / L or higher. A21 The upper limit is more preferably 30,000 μmol / L or less, even more preferably 10,000 μmol / L or less. It is particularly preferably 5,000 μmol / L or less, especially preferably 2,500 μmol / L or less, and most preferably 500 μmol / L or less.

[0136] M B The concentration is preferably 1 to 50,000 μmol / L. B A concentration of 1 μmol / L or higher is sufficient to suppress the analysis of polymerization inhibitors. B By having a concentration of 50,000 μmol / L or less, the amount of impurities produced when a methacrylic acid polymer is manufactured by polymerization of the methacrylic acid-containing composition according to the second embodiment can be reduced, thereby preventing adverse effects on the physical properties of the polymer. B The lower limit is more preferably 10 μmol / L or more, even more preferably 100 μmol / L or more, particularly preferably 1000 μmol / L or more, especially preferably 1500 μmol / L or more, and most preferably 2000 μmol / L or more. BThe upper limit is more preferably 10000 μmol / L or less, even more preferably 5000 μmol / L or less, particularly preferably 3000 μmol / L or less, and especially preferably 2500 μmol / L or more.

[0137] (Concentration of methacrylic acid) In the first embodiment of the methacrylic acid-containing composition according to the second aspect, the concentration of methacrylic acid is 98.00 to 99.99% by mass. 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 according to the second aspect can be reduced, and it can be prevented from adversely affecting the physical properties of the polymer. Further, when the concentration of methacrylic acid is 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, even more preferably 99.00% or more, particularly preferably 99.50% or more, and most preferably 99.80% by mass or more.

[0138] (Component C) In the first embodiment of the methacrylic acid-containing composition according to the second aspect, as long as the concentration of methacrylic acid satisfies 98.00 to 99.99% by mass, it may further contain component C which is another compound. Examples of component C include impurities generated in the process of producing methacrylic acid. For example, methacrylic acid may contain diacetyl as an impurity, but from the viewpoint of reducing the coloring of the methacrylic acid-containing composition, the concentration of diacetyl is preferably 55 μmol / L or less, more preferably 20 μmol / L or less, even more preferably 10 μmol / L or less, and particularly preferably 1 μmol / L or less.

[0139] (Analysis of methacrylic acid-containing composition) The presence of methacrylic acid in a methacrylic acid-containing composition can be confirmed, for example, by GC-MS measurement. If the GC-MS chart of the methacrylic acid-containing composition shows a peak at the same retention time as the standard of component A21, and the m / z value detected in the mass spectrum of that peak matches the exact mass of component A21, then the methacrylic acid-containing composition can be determined to contain component A21. If a standard of component A21 is unavailable, the peak can be determined to be component A21 if the mass spectrum pattern of the peak appearing in the GC-MS chart of the methacrylic acid-containing composition matches the mass spectrum pattern of component A21 recorded in a mass spectrum database. In other words, the methacrylic acid-containing composition can be determined to contain component A21. Examples of mass spectrum databases include NIST20, NIST17, NIST14, and NIST14s. Furthermore, if the volatility is low and detection by GC-MS measurement is not possible, detection can be performed using LC-MS. The presence of components B, C, and water can also be confirmed by the same method. Furthermore, the concentration of methacrylic acid can be calculated, for example, by performing a GC-FID measurement of the methacrylic acid-containing composition, quantifying it using the area percentage method, and correcting it using the moisture concentration quantified with a Karl Fischer moisture meter. The concentration of component A21 can be calculated, for example, by performing a GC measurement of the methacrylic acid-containing composition and quantifying it using the internal standard method. If a standard sample of component A21 cannot be obtained and quantification cannot be performed by the internal standard method, the concentration of component A21 can be calculated using the following formula by performing a GC-FID measurement of any organic compound with a known concentration under the same conditions as the methacrylic acid-containing composition.

[0140]

number

[0141] Here, N is the number of carbon atoms in one molecule of an organic compound with a known concentration. A21 is the number of carbon atoms in one molecule of component A21, SA21 is the peak area of ​​component A21, S is the peak area of ​​the organic compound with a known concentration, and M is the concentration (μmol / L) of the organic compound with a known concentration.

[0142] If the volatility is low and quantification by GC measurement is not possible, quantification can be performed using chromatographic methods such as LC. The concentrations of components B and C can also be calculated using the same method as for component A21 described above. Furthermore, the presence of water in the methacrylic acid-containing composition, and its concentration, can be confirmed by the Karl Fischer method.

[0143] (Component B) In the second embodiment of the second aspect, the methacrylic acid-containing composition preferably contains component B. The preferred form of component B is the same as in the first embodiment. Furthermore, component B may be one type or two or more types.

[0144] (Concentration of component B) M B The preferred mode is the same as in the first embodiment.

[0145] (Concentration of methacrylic acid) The preferred concentration of methacrylic acid is the same as in the first embodiment.

[0146] (Component C) The details and preferred form of component C are the same as in the first embodiment.

[0147] (Analysis of methacrylic acid-containing compositions) The method for confirming that the methacrylic acid-containing composition contains component B, component C, and water, and the method for measuring the concentrations of methacrylic acid, component B, component C, and water, are the same as in the first embodiment.

[0148] [Methacrylic acid-containing composition production method] A method for producing a methacrylic acid-containing composition according to the second embodiment includes adding component A21 and, if necessary, component B to methacrylic acid. The methacrylic acid may be a commercially available product, or methacrylic acid produced by known methods such as the acetone cyanohydrin (ACH) method or the C4 direct oxidation method may be used. Components A21 and B may be commercially available products, or synthesized by known methods may be used. When using methacrylic acid produced by known methods such as the acetone cyanohydrin (ACH) method or the C4 direct oxidation method, component A21 or component B may be added as a raw material or during the manufacturing process to produce the methacrylic acid-containing composition. Furthermore, if component A21 or component B is produced as a by-product in the methacrylic acid manufacturing process, the methacrylic acid-containing composition may be produced by leaving a portion of the produced component A21 or component B.

[0149] [Methods for evaluating storage stability and thermal stability] The methacrylic acid-containing composition according to the second embodiment exhibits high quality stability during storage. Methods for evaluating the quality stability of the methacrylic acid-containing composition during storage include, for example, actually storing the methacrylic acid-containing composition for a long period and confirming the decrease in polymerization inhibitor. Alternatively, from the viewpoint of ease of operation, a method of heating the methacrylic acid-containing composition for a short time and confirming the decrease in polymerization inhibitor may 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 this invention, the quality stability of the methacrylic acid-containing composition during storage was evaluated based on the decrease in polymerization inhibitor when the methacrylic acid-containing composition was stored at 25°C for 21 days.

[0150] [Methacrylic acid ester production method] The method for producing methacrylic acid ester according to the second embodiment includes a step of esterifying the methacrylic acid-containing composition according to the second embodiment. The alcohol to be reacted with the methacrylic acid-containing composition is not particularly limited, and examples thereof include methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, and the like. Examples of the resulting methacrylic acid ester include methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, butyl methacrylate, isobutyl methacrylate, and the like. The esterification reaction can be carried out in the presence of an acidic catalyst such as a sulfonic acid type cation exchange resin. The temperature during the esterification reaction is preferably 50 to 200°C. The pressure during the esterification reaction, the position of the catalyst in the reactor, the proportion of the catalyst in the reactor, etc. are not particularly limited, and the commonly used forms can be applied.

[0151] [Method for producing methacrylic acid polymer according to the second aspect] The method for producing a methacrylic acid polymer according to the second aspect includes a step of polymerizing a polymerizable composition containing a methacrylic acid-containing composition according to the second aspect.

[0152] The polymerizable composition may contain, if necessary, a monomer copolymerizable with methacrylic acid and other additives.

[0153] Examples of the monomer copolymerizable with methacrylic acid include the following. Methacrylic acid esters such as methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, iso-butyl methacrylate, tert-butyl methacrylate, 2-ethylhexyl methacrylate, phenyl methacrylate, or benzyl methacrylate; Acrylic acid esters such as methyl acrylate, ethyl acrylate, n-butyl acrylate, iso-butyl acrylate, tert-butyl acrylate, or 2-ethylhexyl acrylate; Unsaturated carboxylic acids such as acrylic acid, maleic acid, or itaconic acid; Unsaturated carboxylic acid anhydrides such as maleic anhydride or itaconic anhydride; Maleimides such as N-phenylmaleimide or N-cyclohexylmaleimide; 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, or 2-hydroxypropyl methacrylate, or other hydroxyl group-containing vinyl monomers; Vinyl esters such as vinyl acetate or vinyl benzoate; Vinyl chloride, vinylidene chloride, and their derivatives; Nitrogen-containing vinyl monomers such as methacrylamide or acrylonitrile; Epoxy group-containing monomers such as glycidyl acrylate or glycidyl methacrylate; Aromatic vinyl monomers such as styrene or α-methylstyrene; Alkane diol 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; 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; Vinyl monomers having two or more ethylenically unsaturated bonds in their molecules, such as divinylbenzene; Unsaturated polyester prepolymer obtained from at least one polycarboxylic acid containing an ethylenically unsaturated polycarboxylic acid and at least one diol; A vinyl ester prepolymer obtained by modifying the terminals of epoxy groups with acrylic.

[0154] Among the above, the monomer copolymerizable with methacrylic acid is preferably at least one selected from the group consisting of methacrylic acid esters and acrylic acid esters. The monomer copolymerizable with methacrylic acid is more preferably a methacrylic acid ester, and particularly preferably methyl methacrylate.

[0155] The monomer copolymerizable with methacrylic acid may be one type or two or more types. Furthermore, if component A21 is a monomer copolymerizable with methacrylic acid, component A21 may be used as the monomer copolymerizable with methacrylic acid, or a monomer copolymerizable with methacrylic acid may be used separately from component A21.

[0156] In the polymerizable composition, the content of monomers copolymerizable with methacrylic acid is preferably 50.00 to 99.99 parts by mass per 100 parts by mass of the polymerizable composition. The lower limit of the content of monomers copolymerizable with methacrylic acid is more preferably 60 parts by mass or more, even more preferably 70 parts by mass or more, particularly preferably 80 parts by mass or more, and most preferably 90 parts by mass or more, per 100 parts by mass of the polymerizable composition. The upper limit of the content of monomers copolymerizable with methacrylic acid is more preferably 99.9 parts by mass or less, and even more preferably 99 parts by mass or less, per 100 parts by mass of the polymerizable composition.

[0157] Other additives include polymerization initiators. The polymerizable composition may also contain, as needed, chain transfer agents, release agents, lubricants, plasticizers, antioxidants, antistatic agents, light stabilizers, UV absorbers, flame retardants, flame retardant aids, polymerization inhibitors, fillers, pigments, dyes, silane coupling agents, leveling agents, defoamers, fluorescent agents, etc. The other additives may be one type or two or more types.

[0158] Examples of polymerization initiators include the following: 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(cyclohexanecarbonitride), and dimethyl-2,2'-azobisisobutyrate; Benzoyl peroxide, 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane, 1,1-bis(t-butylperoxy)cyclohexane, 1,1-bis(t-butylperoxy)-3,5,5-trimethylcyclohexane, t-butylperoxy-2-ethylhexanoate, t-butylperoxyisobutyrate, t-butylperoxybenzoate, t-hexylperoxybenzoate, t-butylperoxyisopropyl monocarbonate, t-butylperoxy-3,5,5-trimethylhexanoate, t-butylperoxylaurate, t-butylperoxyacetate, t-hexylperoxyisopropyl monocarbonate, t-hexyl peroxy Organic peroxides such as -oxy-2-ethylhexanoate, t-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 peroxyisononate, 1,1,2-trimethylpropyl peroxyisononate, di-t-butyl peroxide, di-t-hexyl peroxide, lauroyl peroxide, and dilauroyl peroxide; Persulfate compounds such as potassium persulfate; A redox polymerization initiator.

[0159] Among the above, from the viewpoint of storage stability and reactivity with methacrylic acid and copolymerizable monomers, the polymerization initiator is preferably at least one selected from the group consisting of azo compounds and organic peroxides. The amount of polymerization initiator used is preferably 0.0001 to 1 part by mass per 100 parts by mass of methacrylic acid and monomers copolymerizable with methacrylic acid.

[0160] Polymerization methods for polymerizable compositions include, for example, bulk polymerization, solution polymerization, emulsion polymerization, and suspension polymerization. The polymerization temperature is preferably 125 to 210°C. This allows for obtaining an appropriate polymerization rate. The lower limit of the polymerization temperature is more preferably 130°C or higher, and the upper limit is more preferably 180°C or lower. The polymerization time is not particularly limited and can be, for example, 0.5 to 24 hours.

[0161] [Methacrylic acid-containing composition according to the third embodiment] The methacrylic acid-containing composition according to the third embodiment contains methacrylic acid and component A3, which is a compound represented by the following formula (31). The concentration of methacrylic acid is 98.00 to 99.99% by mass.

[0162] [ka]

[0163] In formula (31), R 1c , R 2c , R 3c , R 4c , R 5c , R 6c and R 7c This independently represents a hydrogen atom, an alkyl group, an alkenyl group, an aryl group, a hydroxyl group, an alkoxy group, an amino group, a carbonyl group, a monovalent group, an alkylthio group, or an arylthio group. Furthermore, the methacrylic acid-containing composition may also contain polymerization inhibitors (component B), 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 explained in detail below.

[0164] (Methacrylic acid) The methacrylic acid-containing composition according to the third embodiment contains methacrylic acid. Methacrylic acid can be produced, for example, as a by-product of the acetone cyanohydrin (ACH) process or as an intermediate of the C4 direct oxidation process. The methacrylic acid contained in the methacrylic acid-containing composition is preferably produced by the C4 direct oxidation process, and more preferably produced by the C4 direct oxidation process using biomass-derived isobutanol as a starting material.

[0165] (Ingredient A3) The methacrylic acid-containing composition according to the third embodiment contains the compound represented by formula (31) (component A3). The inclusion of component A3 in the methacrylic acid-containing composition suppresses the decomposition of polymerization inhibitors during storage of the methacrylic acid-containing composition. The reason for this is presumed to be as follows.

[0166] Methacrylic acid is known to polymerize due to radicals generated during storage, and a polymerization inhibitor (component B) is added to prevent polymerization. Component B has a polymerization inhibitory function by trapping radicals generated during the storage of methacrylic acid, but because the polymerization inhibitor decomposes into other compounds when trapping radicals, the concentration of component B in the methacrylic acid-containing composition gradually decreases during storage, and the polymerization inhibitory function gradually deteriorates. Furthermore, the amount of unwanted decomposition products generated by component B trapping radicals gradually increases. An example of a radical generated during the storage of methacrylic acid is the hydroxyl radical, which is generated when oxygen molecules absorb ultraviolet light from sunlight. Component A3 is a π-conjugated compound with a benzene ring, so it absorbs ultraviolet light, and its absorption wavelength changes depending on the type of substituent. Component A3 can absorb ultraviolet light across a wide range of wavelengths. Therefore, when a methacrylic acid-containing composition contains component A3, ultraviolet light across a wide range of wavelengths is absorbed, and the generation of hydroxyl radicals is suppressed. Therefore, since the number of radicals that component B needs to trap is reduced, the decrease in the concentration of component B and the generation of degradation products can be suppressed.

[0167] The molecular weight of component A3 is preferably 2000 or less. By having a molecular weight of 2000 or less, the number of benzene rings per unit mass in component A3 can be increased, so that the effects of the present invention can be obtained with a small mass. The molecular weight of component A3 is more preferably 1600 or less, even more preferably 1200 or less, and particularly preferably 800 or less.

[0168] R in equation (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 carbonyl group, a monovalent group, an alkylthio group, or an arylthio group. 1c , R 2c , R 3c , R 4c , R 5c , R 6c and R 7c They may be the same or different.

[0169] R 1c , R 2c , R 3c , R 4c , R 5c , R 6c and R 7c When the above conditions are met, the π-conjugated system of component A3 is maintained, and ultraviolet light of a wide range of wavelengths can be absorbed, thereby suppressing the generation of hydroxyl radicals and obtaining the effects of the present invention. From the viewpoint 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 7cIt is preferably a monovalent group comprising 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 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, an alkoxy group having 1 to 5 carbon atoms, a carboxyl group, or an alkoxycarbonyl group having 2 to 6 carbon atoms; even more preferably a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a hydroxyl group; even more preferably a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an s-butyl group, an i-butyl group, a t-butyl group, or a hydroxyl group; and most preferably a hydrogen atom, a methyl group, or a hydroxyl group.

[0170] The alkyl group is a linear (linear or branched) alkyl group or a cyclic alkyl group. Alkyl groups having 1 to 20 carbon atoms are preferred, alkyl groups having 1 to 10 carbon atoms are more preferred, and alkyl groups having 1 to 5 carbon atoms are even more preferred. Examples of linear alkyl groups include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, s-butyl group, t-butyl group, n-pentyl group, isopentyl group, hexyl group, octyl group, decyl group, hydroxymethyl group, 1-hydroxyethyl group, and 2-hydroxyethyl group, with methyl group, ethyl group, n-propyl group, and isopropyl group being preferred. Examples of cyclic alkyl groups include cyclopentyl group, cyclohexyl group, and cyclooctyl group.

[0171] The alkenyl group is a linear (linear or branched) alkenyl group or a cyclic alkenyl group. Alkenyl groups with 2 to 20 carbon atoms are preferred, alkenyl groups with 2 to 10 carbon atoms are more preferred, and alkenyl groups with 2 to 5 carbon atoms are even more preferred. Examples of linear alkenyl groups include vinyl, 1-propenyl, isopropenyl, 2-butenyl, 1,3-butadienyl, 2-pentenyl, and 2-hexenyl groups. Examples of cyclic alkenyl groups include cyclopentenyl and cyclohexenyl groups.

[0172] 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 heteroaryl groups containing oxygen, nitrogen, sulfur, etc. Examples of aryl groups include phenyl, mesityl, naphthyl, 2-methylphenyl, 3-methylphenyl, 4-methylphenyl, 2,3-dimethylphenyl, 2,4-dimethylphenyl, 2,5-dimethylphenyl, 2,6-dimethylphenyl, 2-ethylphenyl, isoxazolyl, isothiazolyl, imidazolyl, oxazolyl, thiazolyl, thiadiazolyl, thienyl, triazolyl, tetrazolyl, pyridyl, pyrazinyl, pyrimidinyl, pyridadinyl, pyrazolyl, pyrrolyl, furyl, fluzanyl, isoquinolyl, isoindolyl, indolyl, quinolyl, pyridothiazolyl, benzimidazolyl, benzoxazolyl, benzothiazolyl, benzotriazolyl, benzofuranyl, imidazopyridinyl, triazopyridinyl, and prinyl groups.

[0173] 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 even more preferably an alkoxy group having 1 to 6 carbon atoms. Examples of alkoxy groups include methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, s-butoxy, t-butoxy, n-pentoxy, isopentoxy, and phenoxy groups.

[0174] The amino group includes an amino group (-NH2) (0 carbon atoms) with no substituents on the nitrogen atom, and an amino group in which some or all of the hydrogen atoms bonded to the nitrogen atom are substituted with carbon atoms. The number of carbon atoms in the amino group in which some 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 even more preferably 1 to 6. Examples of amino groups include an unsubstituted amino group (-NH2), methylamino group, ethylamino group, propylamino group, butylamino group, dimethylamino group, diethylamino group, anilino group, toluidino group, anisidino group, diphenylamino group, and N-methyl-N-phenylamino group.

[0175] Examples of monovalent groups containing a carbonyl group include formyl group, acyl group, carboxyl group, amide group, alkoxycarbonyl group, thiocarboxyl group, thioester group, etc., with monovalent groups containing a carbonyl group having 1 to 6 carbon atoms being preferred.

[0176] An acyl group is a substituent formed by linking a carbonyl group with an alkyl group, alkenyl group, or aryl group. The total number of carbon atoms derived from the carbonyl group (1) and the alkyl group, alkenyl group, or aryl group of the acyl group is preferably 2 to 20, more preferably 2 to 10, and even more preferably 2 to 6. Examples of acyl groups include acetyl group, propionyl group, butylcarbonyl group, vinylcarbonyl group, and benzoyl group.

[0177] The amide group includes an amide group (-CONH2) without substituents on the nitrogen atom, and an amide group in which some or all of the hydrogen atoms bonded to the nitrogen atom are substituted with carbon atoms. The total number of carbon atoms in the amide group is the sum of the carbon atoms derived from the carbonyl group (1) and the carbon atoms substituted on the nitrogen atom, which is preferably 1 to 20, more preferably 1 to 10, and even more preferably 1 to 5. Examples of amide groups include unsubstituted amide groups, N-methylamide groups, N-ethylamide groups, N-phenylamide groups, N,N-dimethylamide groups, and N-methyl-N-phenylamide groups.

[0178] An alkoxycarbonyl group is a substituent formed by linking a carbonyl group and an alkoxy group, and is also called an ester group. The total number of carbon atoms from the carbonyl group (1) and the alkoxy group is preferably 2 to 20, more preferably 2 to 10, and even more preferably 2 to 6. Examples of alkoxycarbonyl groups include methoxycarbonyl group, ethoxycarbonyl group, butoxycarbonyl group, and phenoxycarbonyl group.

[0179] A thioester group is a substituent formed by linking a carbonyl group with an alkylthio or arylthio group. The total number of carbon atoms derived from the carbonyl group (1) and the alkylthio or arylthio group is preferably 2 to 20, more preferably 2 to 10, and even more preferably 2 to 6. Examples of thioester groups include methylthiocarbonyl group, ethylthiocarbonyl group, butylthiocarbonyl group, and phenylthiocarbonyl group.

[0180] Furthermore, the monovalent group containing a carbonyl group may be a substituent in which one or more hydrogen atoms of an alkyl group are substituted with a carbonyl group. Examples of such substituents include 2-acetoxyethyl group, 2-acetoethyl group, and 2-(acetoacetoxy)ethyl group.

[0181] 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 even more preferably an alkylthio group having 1 to 5 carbon atoms. Examples of alkylthio groups include methylthio group, ethylthio group, propylthio group, isopropylthio group, and the like.

[0182] 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 even more preferably an arylthio group having 6 to 10 carbon atoms. Examples of arylthio groups include phenylthio groups and tolylthio groups.

[0183] Among the compounds that satisfy the above conditions, from the viewpoint of quality stability during storage of methacrylic acid-containing compositions, component A3 is t-butylphenyl ether, isopropylphenyl ether, 1-isopropoxy-3-methylbenzene, 4-isopropoxyphenol, 1-t-butoxy-4-methylbenzene, 2-(2,4-dimethyl-6-t-butylphenoxy)-2-methylpropionic acid, 2-(2,6-di-t-butyl-4-methylphenoxy)-2-methylpropionic acid, 2-(4-methoxyphenoxy)-2-methylpropionic acid, 2-(4-hydroxyphenoxy)-2-methylpropionic acid, 2-(2,4-dimethyl-6-t- Methyl butylphenoxy)-2-methylpropionate, methyl 2-(2,6-di-t-butyl-4-methylphenoxy)-2-methylpropionate, methyl 2-(4-methoxyphenoxy)-2-methylpropionate, or methyl 2-(4-hydroxyphenoxy)-2-methylpropionate are preferred, t-butylphenyl ether, isopropylphenyl ether, 1-isopropoxy-3-methylbenzene, 4-isopropoxyphenol, or 2-(4-methoxyphenoxy)-2-methylpropionic acid are more preferred, and t-butylphenyl ether or 2-(4-methoxyphenoxy)-2-methylpropionic acid are even more preferred.

[0184] Component A3 may be one type or two or more types.

[0185] (Component B) The methacrylic acid-containing composition according to the third embodiment preferably contains a polymerization inhibitor (component B). In this specification, a polymerization inhibitor means a compound that has the function of suppressing the polymerization reaction of methacrylic acid. Examples of polymerization inhibitors include phenolic compounds, quinone compounds, nitrobenzene compounds, N-oxyl compounds, amine compounds, phosphorus-containing compounds, sulfur-containing compounds, iron-containing compounds, copper-containing compounds, and manganese-containing compounds. By containing component B, the polymerization reaction of methacrylic acid by the radical polymerization mechanism can be suppressed during storage of methacrylic acid. In addition, component B can trap the aforementioned hydroxyl radicals that are generated during storage of methacrylic acid. That is, when the methacrylic acid-containing composition contains component B in addition to component A3, the amount of hydroxyl radicals can be reduced by two different mechanisms: component A3 suppresses the generation of hydroxyl radicals, and component B removes the generated hydroxyl radicals. Therefore, it is considered that the decrease of component B and the generation of decomposition products can be efficiently suppressed.

[0186] Examples of polymerization inhibitors that are phenolic compounds include alkylphenols, hydroxyphenols, aminophenols, nitrophenols, nitrosophenols, alkoxyphenols, and tocopherols.

[0187] Examples of alkylphenols include o-cresol, m-cresol, p-cresol, 2-t-butyl-4-methylphenol, 2,4-dimethyl-6-t-butylphenol, 2,6-di-t-butyl-4-methylphenol, 2-t-butylphenol, 4-t-butylphenol, 2,4-di-t-butylphenol, 2-methyl-4-t-butylphenol, 4-t-butyl-2,6-dimethylphenol, 2,2'-methylenebis(6-t-butyl-4-methylphenol), 2,2'-methylenebis(4-ethyl-6-t-butylphenol), 4,4'-thiobis(3-methyl-6-t-butylphenol), and 3,5-di-t-butyl-4-hydroxytoluene.

[0188] Examples of hydroxyphenols include hydroquinone, 2-methylhydroquinone, 2-t-butylhydroquinone, 2,5-di-t-butylhydroquinone, 2,6-di-t-butylhydroquinone, 2,5-di-t-amylhydroquinone, 2-t-butylmethoxyhydroquinone, 2,3,5-trimethylhydroquinone, 2,5-dichlorohydroquinone, 1,2-dihydroxybenzene, 2-acetylhydroquinone, 4-methylcatechol, 4-t-butylcatechol, 2-methylresorcinol, 4-methylresorcinol, and 2,3-dihydroxyacetophenone.

[0189] Examples of aminophenols include o-aminophenol, m-aminophenol, p-aminophenol, 2-(N,N-dimethylamino)phenol, and 4-(ethylamino)phenol.

[0190] Examples of nitrophenols include o-nitrophenol, m-nitrophenol, p-nitrophenol, and 2,4-dinitrophenol. Examples of nitrosophenols include o-nitrosophenol, m-nitrosophenol, p-nitrosophenol, and α-nitroso-β-naphthol.

[0191] Examples of alkoxyphenols include 2-methoxyphenol, 2-ethoxyphenol, 2-isopropoxyphenol, 2-t-butoxyphenol, 4-methoxyphenol, 4-ethoxyphenol, 4-propoxyphenol, 4-butoxyphenol, 4-t-butoxyphenol, 4-heptoxyphenol, hydroquinone monobenzyl ether, t-butyl-4-methoxyphenol, di-t-butyl-4-methoxyphenol, pyrogallol-1,2-dimethyl ether, and hydroquinone monobenzoate.

[0192] Examples of tocopherols include α-tocopherol and 2,3-dihydro-2,2-dimethyl-7-hydroxybenzofuran.

[0193] Examples of polymerization inhibitors that are quinone compounds 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.

[0194] Examples of polymerization inhibitors that are nitrobenzene compounds include nitrobenzene, o-dinitrobenzene, m-dinitrobenzene, p-dinitrobenzene, 2,4-dinitrotoluene, dinitrojulene, and 2,2-diphenyl-1-picrylhydrazyl.

[0195] Examples of polymerization inhibitors that are N-oxyl compounds include 4-hydroxy-2,2,6,6-tetramethyl-piperidine-N-oxyl, 4-oxo-2,2,6,6-tetramethyl-piperidine-N-oxyl, 4-acetoxy-2,2,6,6-tetramethyl-piperidine-N-oxyl, 2,2,6,6-tetramethyl-piperidine-N-oxyl, piperidine-1-oxyl, 4-(dimethylamino)-2,2,6,6-tetramethyl-piperidine-N-oxyl, 4-amino-2,2,6,6-tetramethyl-piperidine-N-oxyl, 4-ethanoloxy-2,2,6,6-tetramethyl-piperidine-N-oxyl, and 4-benzoyloxy-2,2,6,6-tetramethylpiperidine-N-oxyl Examples include 2,2,5,5-tetramethyl-piperidine-N-oxyl, 3-amino-2,2,5,5-tetramethyl-piperidine-N-oxyl, 4,4',4''-tris(2,2,6,6-tetramethyl-piperidine-N-oxyl) phosphite, 3-oxo-2,2,5,5-tetramethylpyrrolidine-N-oxyl, pyrrolidine-1-oxyl, 2,2,5,5-tetramethyl-1-oxa-3-azacyclopentyl-3-oxy, 2,2,5,5-tetramethyl-3-pyrrolinyl-1-oxy-3-carboxylic acid, 2,2,3,3,5,5,6,6-octamethyl-1,4-diazacyclohexyl-1,4-dioxy, di-tert-butyl nitroxide, di-tert-amyl nitroxide, etc.

[0196] Examples of polymerization inhibitors that are amine compounds include N,N-diphenylamine, alkylated diphenylamine, 4,4'-dicumyl-diphenylamine, 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, and each group consists of 1 to 4 carbon atoms independently of each other, 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, Examples include N,N'-di-2-naphthyl-p-phenylenediamine, N,N-diethylhydroxylamine, 1,4-benzenediamine, N-(1,4-dimethylpentyl)-N'-phenyl-1,4-benzenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-1,4-benzenediamine, 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline, 2,2,4-trimethyl-1,2-dihydroquinoline polymer, aldol-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, and 1-hydroxy-4-benzoyloxy-2,2,6,6-tetramethylpiperidine.

[0197] Examples of polymerization inhibitors containing phosphorus include triphenylphosphine, triphenyl phosphite, triethyl phosphite, tris(isodecyl) phosphite, tris(tridecyl) phosphite, phenyldiisooctyl phosphite, phenyldiisodecyl phosphite, phenyldi(tridecyl) phosphite, diphenylisooctyl phosphite, diphenylisodecyl phosphite, diphenyltridecyl phosphite, phosphonic acid [1,1-diphenyl-4,4'-diylbistetrakis-2,4-bis(1,1-dimethylethyl)phenyl]ester, tris(nonylphenyl) phosphite, 4,4'-isopropylidenediphenolalkyl phosphite, tris(2,4-di-tert-butylphenyl) phosphite, tris(biphenyl) phosphite, and distearylpentaerythritol. Examples include di(2,4-di-tert-butylphenyl)pentaerythritol diphosphite, di(nonylphenyl)pentaerythritol diphosphite, phenylbisphenol A pentaerythritol diphosphite, tetra(tridecyl)-4,4'-butylidenebis(3-methyl-6-tert-butylphenol) diphosphite, hexa(tridecyl)-1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane triphosphite, 3,5-di-tert-butyl-4-hydroxybenzyl phosphate diethyl ester, sodium-bis(4-tert-butylphenyl) phosphate, sodium-2,2'-methylene-bis(4,6-di-tert-butylphenyl) phosphate, and 1,3-bis(diphenoxyphosphonyloxy)benzene.

[0198] Examples of polymerization inhibitors containing sulfur include diphenyl sulfide, phenothiazine, 3-oxofhenothiazine, 5-oxofhenothiazine, phenothiazine dimers, 1,4-dimercaptobenzene, 1,2-dimercaptobenzene, 2-mercaptophenol, 4-mercaptophenol, 2-(methylthio)phenol, 3,7-bis(dimethylamino)phenothiazinium chloride, and elemental sulfur.

[0199] Examples of polymerization inhibitors that contain iron include iron(III) chloride.

[0200] Examples of polymerization inhibitors containing copper include copper dimethyldithiocarbamate, copper diethyldithiocarbamate, copper dibutyldithiocarbamate, copper salicylate, copper acetate, copper thiocyanate, copper nitrate, copper chloride, copper carbonate, copper hydroxide, copper acrylate, and copper methacrylate.

[0201] Examples of manganese-containing polymerization inhibitors include manganese dialkyldithiocarbamate (the alkyl group is one of methyl, ethyl, propyl, or butyl groups, and may be the same or different), manganese diphenyldithiocarbamate, manganese formate, manganese acetate, manganese octanoate, manganese naphthenate, manganese permanganate, and manganese salts of ethylenediaminetetraacetic acid.

[0202] Among the above, from the viewpoint of quality stability during storage of the methyl methacrylate-containing composition, component B is preferably at least one polymerization inhibitor selected from the group consisting of phenolic compounds, N-oxyl compounds, amine compounds, phosphorus-containing compounds, and sulfur-containing compounds. For example, it is preferably at least one polymerization inhibitor selected from the group consisting of hydroquinone, 4-methoxyphenol, 2,4-dimethyl-6-t-butylphenol, 2,6-di-t-butyl-4-methylphenol, 4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl, N,N-diphenylamine, N-nitrosodiphenylamine, triphenyl phosphite, and phenothiazine. Component B is more preferably a phenolic compound, for example at least one polymerization inhibitor selected from the group consisting of hydroquinone, 4-methoxyphenol, 2,4-dimethyl-6-t-butylphenol, and 2,6-di-t-butyl-4-methylphenol. Component B is particularly preferably at least one polymerization inhibitor selected from the group consisting of, for example, hydroquinone and 4-methoxyphenol.

[0203] Component B may be one type or two or more types. If a methacrylic acid-containing composition contains a compound that corresponds to both component A3 and component B, that compound shall be considered as component A3. In other words, if a methacrylic acid-containing composition contains both component A3 and component B, it means that it contains a different component B. If two or more compounds that correspond to both component A3 and component B are contained, the compound with the highest molar concentration in the methacrylic acid-containing composition shall be considered as component A3, and the other compounds shall be considered as component B.

[0204] (Concentrations of components A3 and B) The concentration of component A3 is M A3 (μmol / L), the concentration of component B is M B When expressed as (μmol / L), from the viewpoint of the efficiency of suppressing the formation of methacrylic acid dimer and pyruvate, M B / M A3It is preferably 0.005 to 100, and more preferably 0.05 to 10.

[0205] M A3 The concentration is preferably 1 to 50,000 μmol / L. A3 When the concentration is 1 μmol / L or higher, the effect of suppressing the decomposition of polymerization inhibitors can be sufficiently obtained. A3 By having a concentration of 50,000 μmol / L or less, the amount of impurities produced when a methacrylic acid polymer is manufactured by polymerization of the methacrylic acid-containing composition according to the third embodiment can be reduced, and adverse effects on the physical properties of the polymer can be prevented. A3 The lower limit is more preferably 10 μmol / L or higher, even more preferably 30 μmol / L or higher, even more preferably 50 μmol / L or higher, even more preferably 55 μmol / L or higher, and particularly preferably 60 μmol / L or higher. A3 The upper limit is more preferably 25,000 μmol / L or less, even more preferably 10,000 μmol / L or less, and particularly preferably 7,500 μmol / L or less.

[0206] M B The concentration is preferably 1 to 50,000 μmol / L. B By having a concentration of 1 μmol / L or higher, the effect of suppressing the formation of methacrylic acid dimers and pyruvate can be sufficiently obtained. B By having a concentration of 50,000 μmol / L or less, the amount of impurities produced when a methacrylic acid polymer is manufactured by polymerization of the methacrylic acid-containing composition according to the third embodiment can be reduced, and adverse effects on the physical properties of the polymer can be prevented. B The lower limit is more preferably 10 μmol / L or more, even more 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 45,000 μmol / L or less, even more preferably 40,000 μmol / L or less, particularly preferably 35,000 μmol / L or less, especially preferably 30,000 μmol / L or less, and most preferably 25,000 μmol / L or less.

[0207] (Concentration of methacrylic acid) The concentration of methacrylic acid in the methacrylic acid-containing composition according to the third embodiment is 98.00 to 99.99% by mass. By having a methacrylic acid concentration of 98.00% by mass or higher, the amount of impurities produced when a methacrylic acid polymer is manufactured by polymerization of the methacrylic acid-containing composition according to the third embodiment can be reduced, and adverse effects on the physical properties of the polymer can be prevented. Furthermore, by having a methacrylic acid concentration of 99.99% by mass or lower, purification costs can be reduced. The lower limit of the methacrylic acid concentration is more preferably 98.50% or higher, even more preferably 99.00% or higher, and particularly preferably 99.50% or higher.

[0208] (Component C) The methacrylic acid-containing composition according to the third embodiment may further contain component C, which is another compound, as long as the concentration of methacrylic acid satisfies 98.00 to 99.99% by mass. Component C may include impurities generated during the production of methacrylic acid. For example, methacrylic acid may contain diacetyl as an impurity, but from the viewpoint of reducing the discoloration of the methacrylic acid-containing composition, the concentration of diacetyl is preferably 55 μmol / L or less, more preferably 20 μmol / L or less, even more preferably 10 μmol / L or less, and particularly preferably 1 μmol / L or less.

[0209] (Analysis of methacrylic acid-containing compositions) The presence of component A3, component B, component C, and water in a methacrylic acid-containing composition can be confirmed, for example, by GC-MS measurement. If the GC-MS chart of the methacrylic acid-containing composition shows a peak at the same retention time as the component A3 standard, and the m / z value detected in the mass spectrum of that peak matches the exact mass of component A3, then the methacrylic acid-containing composition can be determined to contain component A3. If a standard of component A3 is unavailable, the peak can be determined to be component A3 if the mass spectrum pattern of the peak appearing in the GC-MS chart of the methacrylic acid-containing composition matches the mass spectrum pattern of component A3 recorded in a mass spectrum database. In other words, the methacrylic acid-containing composition can be determined to contain component A3. Examples of mass spectrum databases include NIST20, NIST17, NIST14, and NIST14s. Furthermore, if the volatility is low and detection by GC-MS is not possible, detection can be performed using LC-MS. The presence of component B, component C, and water can also be confirmed by a similar method. Furthermore, the concentration of methacrylic acid can be calculated, for example, by performing a GC-FID measurement of the methacrylic acid-containing composition, quantifying it using the area percentage method, and correcting it using the moisture concentration quantified with a Karl Fischer moisture meter. The concentration of component A3 can be calculated, for example, by performing a GC measurement of the methacrylic acid-containing composition and quantifying it using the internal standard method. If a standard sample of component A3 cannot be obtained and quantification cannot be performed by the internal standard method, the concentration of component A3 can be calculated using the following formula by performing a GC-FID measurement of any organic compound with a known concentration under the same conditions as the methacrylic acid-containing composition.

[0210]

number

[0211] 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 A3is the peak area of ​​component A3, S is the peak area of ​​the organic compound with a known concentration, and M is the concentration (μmol / L) of the organic compound with a known concentration.

[0212] If the volatility is low and quantification by GC measurement is not possible, quantification can be performed using chromatographic methods such as LC. The concentrations of components B and C can also be calculated using the same method as for component A3 described above. Furthermore, the presence of water in the methacrylic acid-containing composition, and its concentration, can be confirmed by the Karl Fischer method.

[0213] [Methacrylic acid-containing composition production method] A method for producing a methacrylic acid-containing composition according to the third embodiment includes adding component A3 to methacrylic acid, preferably adding component A3 and component B to methacrylic acid. The methacrylic acid may be a commercially available product, or methacrylic acid produced by known methods such as the acetone cyanohydrin (ACH) method or the C4 direct oxidation method may be used. Components A3 and B may be commercially available products, or synthesized by known methods. When using methacrylic acid produced by known methods such as the acetone cyanohydrin (ACH) method or the C4 direct oxidation method, component A3 or component B may be added as a raw material or during the manufacturing process to produce the methacrylic acid-containing composition. Furthermore, if component A3 or component B is produced as a by-product in the methacrylic acid manufacturing process, the methacrylic acid-containing composition may be produced by leaving a portion of the produced component A3 or component B.

[0214] [Methods for evaluating storage stability and thermal stability] The methacrylic acid-containing composition according to the third embodiment exhibits high quality stability during storage. Methods for evaluating the quality stability of the methacrylic acid-containing composition during storage include, for example, actually storing the methacrylic acid-containing composition for a long period and confirming the decrease in polymerization inhibitor. Alternatively, from the viewpoint of ease of operation, a method of heating the methacrylic acid-containing composition for a short time and confirming the decrease in polymerization inhibitor may 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 this invention, the quality stability of the methacrylic acid-containing composition during storage was evaluated by the decrease in polymerization inhibitor when the methacrylic acid-containing composition was stored at 25°C for 21 days.

[0215] [Methacrylic acid ester production method] The method for producing methacrylic acid ester according to the third embodiment includes a step of esterifying the methacrylic acid-containing composition according to the third embodiment. The alcohol reacted with the methacrylic acid-containing composition is not particularly limited and includes, for example, methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, etc. The resulting methacrylic acid esters include, for example, methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, butyl methacrylate, isobutyl methacrylate, etc. The esterification reaction can be carried out in the presence of an acidic catalyst such as a sulfonic acid type cation exchange resin. The temperature during the esterification reaction is preferably 50 to 200°C. The pressure during the esterification reaction, the position of the catalyst in the reactor, and the proportion of the catalyst in the reactor are not particularly limited, and commonly used configurations can be applied.

[0216] [Methacrylic acid polymer production method according to the third embodiment] A method for producing a methacrylic acid polymer according to the third embodiment includes a step of polymerizing a polymerizable composition containing the methacrylic acid-containing composition according to the third embodiment.

[0217] The polymerizable composition may optionally contain monomers copolymerizable with methacrylic acid and other additives.

[0218] Examples of monomers copolymerizable with methacrylic acid include the following: Methacrylic acid esters such as methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, iso-butyl methacrylate, tert-butyl methacrylate, 2-ethylhexyl methacrylate, phenyl methacrylate, or benzyl methacrylate; Acrylic acid esters such as methyl acrylate, ethyl acrylate, n-butyl acrylate, iso-butyl acrylate, tert-butyl acrylate, or 2-ethylhexyl acrylate; Unsaturated carboxylic acids such as acrylic acid, maleic acid, or itaconic acid; Unsaturated carboxylic acid anhydrides such as maleic anhydride or itaconic anhydride; Maleimides such as N-phenylmaleimide or N-cyclohexylmaleimide; 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, or 2-hydroxypropyl methacrylate, or other hydroxyl group-containing vinyl monomers; Vinyl esters such as vinyl acetate or vinyl benzoate; Vinyl chloride, vinylidene chloride, and their derivatives; Nitrogen-containing vinyl monomers such as methacrylamide or acrylonitrile; Epoxy group-containing monomers such as glycidyl acrylate or glycidyl methacrylate; Aromatic vinyl monomers such as styrene or α-methylstyrene; Alkane diol 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; 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; Vinyl monomers having two or more ethylenically unsaturated bonds in their molecules, such as divinylbenzene; Unsaturated polyester prepolymer obtained from at least one polycarboxylic acid containing an ethylenically unsaturated polycarboxylic acid and at least one diol; A vinyl ester prepolymer obtained by modifying the terminals of epoxy groups with acrylic.

[0219] Among the above, the monomer copolymerizable with methacrylic acid is preferably at least one selected from the group consisting of methacrylic acid esters and acrylic acid esters. The monomer copolymerizable with methacrylic acid is more preferably a methacrylic acid ester, and particularly preferably methyl methacrylate.

[0220] The monomer copolymerizable with methacrylic acid may be one type or two or more types. Furthermore, if component A3 is a monomer copolymerizable with methacrylic acid, component A3 may be used as the monomer copolymerizable with methacrylic acid, or a monomer copolymerizable with methacrylic acid may be used separately from component A3.

[0221] In the polymerizable composition, the content of monomers copolymerizable with methacrylic acid is preferably 50.00 to 99.99 parts by mass per 100 parts by mass of the polymerizable composition. The lower limit of the content of monomers copolymerizable with methacrylic acid is more preferably 60 parts by mass or more, even more preferably 70 parts by mass or more, particularly preferably 80 parts by mass or more, and most preferably 90 parts by mass or more, per 100 parts by mass of the polymerizable composition. The upper limit of the content of monomers copolymerizable with methacrylic acid is more preferably 99.9 parts by mass or less, and even more preferably 99 parts by mass or less, per 100 parts by mass of the polymerizable composition.

[0222] Other additives include polymerization initiators. The polymerizable composition may also contain, as needed, chain transfer agents, mold release agents, lubricants, plasticizers, antioxidants, antistatic agents, light stabilizers, UV absorbers, flame retardants, flame retardant aids, polymerization inhibitors, fillers, pigments, dyes, silane coupling agents, leveling agents, defoamers, fluorescent agents, etc. The other additives may be one type or two or more types.

[0223] Examples of polymerization initiators include the following: 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(cyclohexanecarbonitride), and dimethyl-2,2'-azobisisobutyrate; Benzoyl peroxide, 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane, 1,1-bis(t-butylperoxy)cyclohexane, 1,1-bis(t-butylperoxy)-3,5,5-trimethylcyclohexane, t-butylperoxy-2-ethylhexanoate, t-butylperoxyisobutyrate, t-butylperoxybenzoate, t-hexylperoxybenzoate, t-butylperoxyisopropyl monocarbonate, t-butylperoxy-3,5,5-trimethylhexanoate, t-butylperoxylaurate, t-butylperoxyacetate, t-hexylperoxyisopropyl monocarbonate, t-hexyl peroxy Organic peroxides such as -oxy-2-ethylhexanoate, t-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 peroxyisononate, 1,1,2-trimethylpropyl peroxyisononate, di-t-butyl peroxide, di-t-hexyl peroxide, lauroyl peroxide, and dilauroyl peroxide; Persulfate compounds such as potassium persulfate; A redox polymerization initiator.

[0224] Among the above, from the viewpoint of storage stability and reactivity with methacrylic acid and copolymerizable monomers, the polymerization initiator is preferably at least one selected from the group consisting of azo compounds and organic peroxides. The amount of polymerization initiator used is preferably 0.0001 to 1 part by mass per 100 parts by mass of methacrylic acid and monomers copolymerizable with methacrylic acid.

[0225] Polymerization methods for polymerizable compositions include, for example, bulk polymerization, solution polymerization, emulsion polymerization, and suspension polymerization. The polymerization temperature is preferably 125 to 210°C. This allows for obtaining an appropriate polymerization rate. The lower limit of the polymerization temperature is more preferably 130°C or higher, and the upper limit is more preferably 180°C or lower. The polymerization time is not particularly limited and can be, for example, 0.5 to 24 hours.

[0226] [Methacrylic acid-containing composition according to the fourth embodiment] The methacrylic acid-containing composition according to 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.

[0227] [ka]

[0228] 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 6 to 12 carbon atoms, and these groups may further have substituents. Furthermore, the methacrylic acid-containing composition may also contain other compounds (component C) or water, as long as the concentration of methacrylic acid satisfies 98.00 to 99.99% by mass. Each item will be explained in detail below.

[0229] (Methacrylic acid) The methacrylic acid-containing composition according to the fourth embodiment contains methacrylic acid. Methacrylic acid can be produced, for example, as a by-product of the acetone cyanohydrin (ACH) process or as an intermediate of the C4 direct oxidation process. The methacrylic acid contained in the methacrylic acid-containing composition is preferably produced by the C4 direct oxidation process, and more preferably produced by the C4 direct oxidation process using biomass-derived isobutanol as a starting material.

[0230] (Ingredient A4) The methacrylic acid-containing composition according to the fourth embodiment contains the compound represented by formula (41) (component A4). The inclusion of component A4 in the methacrylic acid-containing composition can suppress the decomposition of the polymerization inhibitor. The reason for this is presumed to be as follows.

[0231] Methacrylic acid is known to polymerize due to radicals generated during storage, and a polymerization inhibitor (component B) is added to prevent polymerization. Component B has a polymerization inhibitory function by trapping radicals generated during the storage of methacrylic acid, but because the polymerization inhibitor decomposes into other compounds when trapping radicals, the concentration of component B in the methacrylic acid-containing composition gradually decreases during storage, and the polymerization inhibitory function gradually deteriorates. Furthermore, the amount of unwanted decomposition products generated when component B traps radicals gradually increases. An example of a radical generated during the storage of methacrylic acid is the hydroxyl radical, which is generated when oxygen molecules absorb ultraviolet light from sunlight. Since component A4 is weakly basic, it is more effective against hydroxyl ions (OH) than against hydroxyl radicals. - The generation of ) is prioritized, and the generation of hydroxyl radicals is suppressed. Therefore, the number of radicals that component B needs to trap is reduced, and thus the decrease in the concentration of component B can be suppressed.

[0232] 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, so that the effects of the present invention can be obtained with a small mass. The molecular weight of component A4 is more preferably 800 or less, even more preferably 600 or less, and particularly preferably 400 or less.

[0233] R in equation (41) d This 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 substituents.

[0234] R dWhen the above conditions are met, the weak basicity of component A4 and its reactivity with acidic substances and radicals are maintained, thus the effects of the present invention can be obtained. Furthermore, because it is a highly stable group, it is possible to prevent component A4 from changing into other compounds during storage. d R 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 It is more preferably a methyl group, ethyl group, vinyl group, isopropenyl group, phenyl group, methylthiophenyl, acetoxyphenyl group, or cyanophenyl group; even more preferably a methyl group, ethyl group, vinyl group, isopropenyl group, methylthiophenyl group, acetoxyphenyl group, or cyanophenyl group; and particularly preferably a methyl group, ethyl group, vinyl group, isopropenyl group, acetoxyphenyl group, or cyanophenyl group.

[0235] Alkyl groups are linear (linear or branched) alkyl groups or cyclic alkyl groups. Examples of linear alkyl groups include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, s-butyl group, t-butyl group, n-pentyl group, and isopentyl group. Among these, methyl group, ethyl group, n-propyl group, and isopropyl group are preferred, with methyl group or ethyl group being more preferred. Examples of cyclic alkyl groups include cyclopropyl group, cyclobutyl group, and cyclopentyl group.

[0236] The alkenyl group is a linear (linear or branched) alkenyl group or a cyclic alkenyl group. Examples of linear alkenyl groups include vinyl, 1-propenyl, isopropenyl, 2-butenyl, 1,3-butadienyl, and 2-pentenyl groups. Among these, vinyl, 1-propenyl, and isopropenyl groups are preferred, with vinyl or isopropenyl groups being more preferred. Examples of cyclic alkenyl groups include cyclopropenyl, cyclobutenyl, and cyclopentenyl groups.

[0237] The aryl group includes heteroaryl groups containing oxygen, nitrogen, sulfur, etc. Examples of aryl groups include phenyl, mesityl, naphthyl, 2-methylphenyl, 3-methylphenyl, 4-methylphenyl, 2,3-dimethylphenyl, 2,4-dimethylphenyl, 2,5-dimethylphenyl, 2,6-dimethylphenyl, 2-ethylphenyl, isoxazolyl, isothiazolyl, imidazolyl, oxazolyl, thiazolyl, thiadiazolyl, thienyl, triazolyl, tetrazolyl, pyridyl, pyrazinyl, pyrimidinyl, pyridadinyl, pyrazolyl, pyrrolyl, furyl, fluzanyl, isoquinolyl, isoindolyl, indolyl, quinolyl, pyridothiazolyl, benzimidazolyl, benzoxazolyl, benzothiazolyl, benzotriazolyl, benzofuranyl, imidazopyridinyl, triazopyridinyl, and prinyl groups.

[0238] R d When the substituent is a substituted alkyl group, alkenyl group, or aryl group, examples of substituents include monovalent groups including alkyl groups, alkenyl groups, aryl groups, hydroxyl groups, alkoxy groups, amino groups, and carbonyl groups, as well as alkylthio groups and arylthio groups. Among these, monovalent groups including hydroxyl groups, alkoxy groups, amino groups, and carbonyl groups, and alkylthio groups are preferred, and hydroxyl groups, methoxy 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 even more preferably 50 or less. d The number of carbon atoms in R is the number of carbon atoms in the substituents of the alkyl, alkenyl, or aryl group. For example, 4-(methylthio)benzonitrile is R d This is considered to be a 4-(methylthio)phenyl group, which has an aryl group with 7 carbon atoms.

[0239] Alkyl substituents are R dThe alkyl group is the same as described above, insofar as 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, and more preferably 1 to 3.

[0240] The alkenyl group as a substituent is R d The above-described alkenyl group is the same as the above-described alkenyl group, insofar as 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 number of carbon atoms of the alkenyl group as a substituent is 2 to 11, preferably 2 to 6, and more preferably 2 to 3.

[0241] The aryl group as a substituent is R d The aryl group is the same as described above, insofar as 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, and more preferably 5 to 7.

[0242] 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. However, R d These are alkyl groups having 1 to 5 carbon atoms, alkenyl groups having 2 to 5 carbon atoms, or aryl groups having 1 to 12 carbon atoms. Examples of alkoxy groups include methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, s-butoxy, t-butoxy, n-pentoxy, isopentoxy, and phenoxy groups.

[0243] The amino group as a substituent includes an amino group (-NH2) (0 carbon atoms) with no substituent on the nitrogen atom, and an amino group in which some or all of the hydrogen atoms bonded to the nitrogen atom are replaced by carbon atoms. The number of carbon atoms in the amino group in which some or all of the hydrogen atoms bonded to the nitrogen atom are replaced by carbon atoms is 1 to 11, preferably 1 to 6, and more preferably 1 to 3. However, Rd The amino group 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 amino groups include an unsubstituted amino group (-NH2), methylamino group, ethylamino group, propylamino group, butylamino group, dimethylamino group, diethylamino group, anilino group, toluidino group, anisidino group, and N-methyl-N-phenylamino group.

[0244] Examples of monovalent groups containing a carbonyl group that can be used as substituents include formyl group, acyl group, carboxyl group, amide group, alkoxycarbonyl group, thiocarboxyl group, and thioester group.

[0245] An acyl group is a substituent formed by linking a carbonyl group with an alkyl group, alkenyl group, or aryl group. The total number of carbon atoms derived from the carbonyl group (1) and the alkyl group, alkenyl group, or aryl group of the acyl group is 2 to 11, preferably 2 to 7, and more preferably 2 to 4. However, R d The acyl group 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 acyl groups include acetyl, propionyl, butylcarbonyl, vinylcarbonyl, and benzoyl groups.

[0246] The amide group includes an amide group (-CONH2) without substituents on the nitrogen atom, and an amide group in which some or all of the hydrogen atoms bonded to the nitrogen atom are replaced by carbon atoms. The number of carbon atoms in the amide group is the sum of the number of carbon atoms derived from the carbonyl group (1) and the number of carbon atoms substituted on the nitrogen atom, and is 1 to 11, preferably 1 to 7, and more preferably 1 to 4. However, R d The amide group 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 amide groups include unsubstituted amide groups, N-methylamide groups, N-ethylamide groups, N-phenylamide groups, N,N-dimethylamide groups, and N-methyl-N-phenylamide groups.

[0247] An alkoxycarbonyl group is a substituent formed by the linkage of a carbonyl group and an alkoxy group, and is also called an ester group. The total number of carbon atoms from the carbonyl group (1) and the alkoxy group is 2 to 11, preferably 2 to 7, and more preferably 2 to 4. However, R d These are alkyl groups having 1 to 5 carbon atoms, alkenyl groups having 2 to 5 carbon atoms, or aryl groups having 1 to 12 carbon atoms. Examples of alkoxycarbonyl groups include methoxycarbonyl groups, ethoxycarbonyl groups, butoxycarbonyl groups, and phenoxycarbonyl groups.

[0248] A thioester group is a substituent formed by linking a carbonyl group with an alkylthio or arylthio group. The total number of carbon atoms derived from the carbonyl group (1) and the alkylthio or arylthio group is 2 to 11, preferably 2 to 7, and more preferably 2 to 4. However, R d These are alkyl groups having 1 to 5 carbon atoms, alkenyl groups having 2 to 5 carbon atoms, or aryl groups having 1 to 12 carbon atoms. Examples of thioester groups include methylthiocarbonyl group, ethylthiocarbonyl group, butylthiocarbonyl group, and phenylthiocarbonyl group.

[0249] Furthermore, the monovalent group containing a carbonyl group may be a substituent in which one or more hydrogen atoms of an alkyl group are substituted with a carbonyl group. Examples of such substituents include 2-acetoxyethyl group, 2-acetoethyl group, and 2-(acetoacetoxy)ethyl group.

[0250] 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. However, R d These are alkyl groups having 1 to 5 carbon atoms, alkenyl groups having 2 to 5 carbon atoms, or aryl groups having 1 to 12 carbon atoms. Examples of alkylthio groups include methylthio, ethylthio, propylthio, and isopropylthio groups.

[0251] 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. However, R d These are alkyl groups having 1 to 5 carbon atoms, alkenyl groups having 2 to 5 carbon atoms, or aryl groups having 1 to 12 carbon atoms. Examples of arylthio groups include phenylthio groups and tolylthio groups.

[0252] Among the compounds that satisfy the above conditions, from the viewpoint of quality stability during storage of the methacrylic acid-containing composition, 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; even more preferably methacrylonitrile, acetonitrile, propionitrile, acrylonitrile, 4-cyanoacetophenone, or 4-(methylthio)benzonitrile; and particularly preferably methacrylonitrile, acetonitrile, propionitrile, acrylonitrile, or 4-cyanoacetophenone.

[0253] Component A4 may consist of one type or two or more types.

[0254] (Component B) The methacrylic acid-containing composition according to the fourth embodiment contains a polymerization inhibitor (component B). In this specification, a polymerization inhibitor means a compound that has the function of suppressing the polymerization reaction of methacrylic acid. Examples of polymerization inhibitors include phenolic compounds, quinone compounds, nitrobenzene compounds, N-oxyl compounds, amine compounds, phosphorus-containing compounds, sulfur-containing compounds, iron-containing compounds, copper-containing compounds, and manganese-containing compounds. By including component B, the polymerization reaction of methacrylic acid by the radical polymerization mechanism can be suppressed during storage of methacrylic acid. In addition, component B can trap the aforementioned hydroxyl radicals that are generated during storage of methacrylic acid. That is, when the methacrylic acid-containing composition contains component B in addition to component A4, the amount of hydroxyl radicals can be reduced by two different mechanisms: component A4 suppresses the generation of hydroxyl radicals, and component B removes the generated hydroxyl radicals. Therefore, it is considered that the decrease of component B can be efficiently suppressed.

[0255] Examples of polymerization inhibitors that are phenolic compounds include alkylphenols, hydroxyphenols, aminophenols, nitrophenols, nitrosophenols, alkoxyphenols, and tocopherols.

[0256] Examples of alkylphenols include o-cresol, m-cresol, p-cresol, 2-t-butyl-4-methylphenol, 2,4-dimethyl-6-t-butylphenol, 2,6-di-t-butyl-4-methylphenol, 2-t-butylphenol, 4-t-butylphenol, 2,4-di-t-butylphenol, 2-methyl-4-t-butylphenol, 4-t-butyl-2,6-dimethylphenol, 2,2'-methylenebis(6-t-butyl-4-methylphenol), 2,2'-methylenebis(4-ethyl-6-t-butylphenol), 4,4'-thiobis(3-methyl-6-t-butylphenol), and 3,5-di-t-butyl-4-hydroxytoluene.

[0257] Examples of hydroxyphenols include hydroquinone, 2-methylhydroquinone, 2-t-butylhydroquinone, 2,5-di-t-butylhydroquinone, 2,6-di-t-butylhydroquinone, 2,5-di-t-amylhydroquinone, 2-t-butylmethoxyhydroquinone, 2,3,5-trimethylhydroquinone, 2,5-dichlorohydroquinone, 1,2-dihydroxybenzene, 2-acetylhydroquinone, 4-methylcatechol, 4-t-butylcatechol, 2-methylresorcinol, 4-methylresorcinol, and 2,3-dihydroxyacetophenone.

[0258] Examples of aminophenols include o-aminophenol, m-aminophenol, p-aminophenol, 2-(N,N-dimethylamino)phenol, and 4-(ethylamino)phenol.

[0259] Examples of nitrophenols include o-nitrophenol, m-nitrophenol, p-nitrophenol, and 2,4-dinitrophenol. Examples of nitrosophenols include o-nitrosophenol, m-nitrosophenol, p-nitrosophenol, and α-nitroso-β-naphthol.

[0260] Examples of alkoxyphenols include 2-methoxyphenol, 2-ethoxyphenol, 2-isopropoxyphenol, 2-t-butoxyphenol, 4-methoxyphenol, 4-ethoxyphenol, 4-propoxyphenol, 4-butoxyphenol, 4-t-butoxyphenol, 4-heptoxyphenol, hydroquinone monobenzyl ether, t-butyl-4-methoxyphenol, di-t-butyl-4-methoxyphenol, pyrogallol-1,2-dimethyl ether, and hydroquinone monobenzoate.

[0261] Examples of tocopherols include α-tocopherol and 2,3-dihydro-2,2-dimethyl-7-hydroxybenzofuran.

[0262] Examples of polymerization inhibitors that are quinone compounds 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.

[0263] Examples of polymerization inhibitors that are nitrobenzene compounds include nitrobenzene, o-dinitrobenzene, m-dinitrobenzene, p-dinitrobenzene, 2,4-dinitrotoluene, dinitrojulene, and 2,2-diphenyl-1-picrylhydrazyl.

[0264] Examples of polymerization inhibitors that are N-oxyl compounds include 4-hydroxy-2,2,6,6-tetramethyl-piperidine-N-oxyl, 4-oxo-2,2,6,6-tetramethyl-piperidine-N-oxyl, 4-acetoxy-2,2,6,6-tetramethyl-piperidine-N-oxyl, 2,2,6,6-tetramethyl-piperidine-N-oxyl, piperidine-1-oxyl, 4-(dimethylamino)-2,2,6,6-tetramethyl-piperidine-N-oxyl, 4-amino-2,2,6,6-tetramethyl-piperidine-N-oxyl, 4-ethanoloxy-2,2,6,6-tetramethyl-piperidine-N-oxyl, and 4-benzoyloxy-2,2,6,6-tetramethylpiperidine-N-oxyl Examples include 2,2,5,5-tetramethyl-piperidine-N-oxyl, 3-amino-2,2,5,5-tetramethyl-piperidine-N-oxyl, 4,4',4''-tris(2,2,6,6-tetramethyl-piperidine-N-oxyl) phosphite, 3-oxo-2,2,5,5-tetramethylpyrrolidine-N-oxyl, pyrrolidine-1-oxyl, 2,2,5,5-tetramethyl-1-oxa-3-azacyclopentyl-3-oxy, 2,2,5,5-tetramethyl-3-pyrrolinyl-1-oxy-3-carboxylic acid, 2,2,3,3,5,5,6,6-octamethyl-1,4-diazacyclohexyl-1,4-dioxy, di-tert-butyl nitroxide, di-tert-amyl nitroxide, etc.

[0265] Examples of polymerization inhibitors that are amine compounds include N,N-diphenylamine, alkylated diphenylamine, 4,4'-dicumyl-diphenylamine, 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, and each group consists of 1 to 4 carbon atoms independently of each other, 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, Examples include N,N'-di-2-naphthyl-p-phenylenediamine, N,N-diethylhydroxylamine, 1,4-benzenediamine, N-(1,4-dimethylpentyl)-N'-phenyl-1,4-benzenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-1,4-benzenediamine, 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline, 2,2,4-trimethyl-1,2-dihydroquinoline polymer, aldol-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, and 1-hydroxy-4-benzoyloxy-2,2,6,6-tetramethylpiperidine.

[0266] Examples of polymerization inhibitors containing phosphorus include triphenylphosphine, triphenyl phosphite, triethyl phosphite, tris(isodecyl) phosphite, tris(tridecyl) phosphite, phenyldiisooctyl phosphite, phenyldiisodecyl phosphite, phenyldi(tridecyl) phosphite, diphenylisooctyl phosphite, diphenylisodecyl phosphite, diphenyltridecyl phosphite, phosphonic acid [1,1-diphenyl-4,4'-diylbistetrakis-2,4-bis(1,1-dimethylethyl)phenyl]ester, tris(nonylphenyl) phosphite, 4,4'-isopropylidenediphenolalkyl phosphite, tris(2,4-di-tert-butylphenyl) phosphite, tris(biphenyl) phosphite, and distearylpentaerythritol. Examples include di(2,4-di-tert-butylphenyl)pentaerythritol diphosphite, di(nonylphenyl)pentaerythritol diphosphite, phenylbisphenol A pentaerythritol diphosphite, tetra(tridecyl)-4,4'-butylidenebis(3-methyl-6-tert-butylphenol) diphosphite, hexa(tridecyl)-1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane triphosphite, 3,5-di-tert-butyl-4-hydroxybenzyl phosphate diethyl ester, sodium-bis(4-tert-butylphenyl) phosphate, sodium-2,2'-methylene-bis(4,6-di-tert-butylphenyl) phosphate, and 1,3-bis(diphenoxyphosphonyloxy)benzene.

[0267] Examples of polymerization inhibitors containing sulfur include diphenyl sulfide, phenothiazine, 3-oxofhenothiazine, 5-oxofhenothiazine, phenothiazine dimers, 1,4-dimercaptobenzene, 1,2-dimercaptobenzene, 2-mercaptophenol, 4-mercaptophenol, 2-(methylthio)phenol, 3,7-bis(dimethylamino)phenothiazinium chloride, and elemental sulfur.

[0268] Examples of polymerization inhibitors that contain iron include iron(III) chloride.

[0269] Examples of polymerization inhibitors containing copper include copper dimethyldithiocarbamate, copper diethyldithiocarbamate, copper dibutyldithiocarbamate, copper salicylate, copper acetate, copper thiocyanate, copper nitrate, copper chloride, copper carbonate, copper hydroxide, copper acrylate, and copper methacrylate.

[0270] Examples of manganese-containing polymerization inhibitors include manganese dialkyldithiocarbamate (the alkyl group is one of methyl, ethyl, propyl, or butyl groups, and may be the same or different), manganese diphenyldithiocarbamate, manganese formate, manganese acetate, manganese octanoate, manganese naphthenate, manganese permanganate, and manganese salts of ethylenediaminetetraacetic acid.

[0271] Among the above, from the viewpoint of quality stability during storage of the methacrylic acid-containing composition, component B is preferably at least one polymerization inhibitor selected from the group consisting of phenolic compounds, N-oxyl compounds, amine compounds, phosphorus-containing compounds, and sulfur-containing compounds. For example, it is preferably at least one polymerization inhibitor selected from the group consisting of hydroquinone, 4-methoxyphenol, 2,4-dimethyl-6-t-butylphenol, 2,6-di-t-butyl-4-methylphenol, 4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl, N,N-diphenylamine, N-nitrosodiphenylamine, triphenyl phosphite, and phenothiazine. Component B is more preferably a phenolic compound, for example at least one polymerization inhibitor selected from the group consisting of hydroquinone, 4-methoxyphenol, 2,4-dimethyl-6-t-butylphenol, and 2,6-di-t-butyl-4-methylphenol. Component B is particularly preferably at least one polymerization inhibitor selected from the group consisting of hydroquinone and 4-methoxyphenol.

[0272] Component B may be one type or two or more types. If a methacrylic acid-containing composition contains a compound that corresponds to both component A4 and component B, that compound shall be considered as component B. In other words, the methacrylic acid-containing composition must contain a component A4 other than that compound. If two or more compounds that correspond to both component A4 and component B are contained, the compound with the highest molar concentration in the methacrylic acid-containing composition shall be considered as component B, and the other compounds shall be considered as component A4.

[0273] (Concentrations of components A4 and B) The concentration of component A4 is M A4 (μmol / L), the concentration of component B is M B When expressed as (μmol / L), from the viewpoint of the efficiency of suppressing the formation of methacrylic acid dimer and pyruvate, M B / M A4 It is preferably 0.005 to 100, and more preferably 0.05 to 10.

[0274] M A4 The concentration is preferably 1 to 40,000 μmol / L. A4 When the concentration is 1 μmol / L or higher, the effect of suppressing the decomposition of polymerization inhibitors can be sufficiently obtained. A4 By having a concentration of 40,000 μmol / L or less, the amount of impurities produced when a methacrylic acid polymer is manufactured by polymerization of the methacrylic acid-containing composition according to the fourth embodiment can be reduced, thereby preventing adverse effects on the physical properties of the polymer. A4 The lower limit is more preferably 10 μmol / L or higher, even more preferably 30 μmol / L or higher, even more preferably 50 μmol / L or higher, even more preferably 60 μmol / L or higher, particularly preferably 70 μmol / L or higher, and especially preferably 80 μmol / L or higher. A4 The upper limit is more preferably 3000 μmol / L or less, even more preferably 25000 μmol / L or less, and particularly preferably 20000 μmol / L or less.

[0275] M B The concentration is preferably 1 to 50,000 μmol / L. B By having a concentration of 1 μmol / L or higher, the effect of suppressing the formation of methacrylic acid dimers and pyruvate can be sufficiently obtained. B By having a concentration of 50,000 μmol / L or less, the amount of impurities produced when a methacrylic acid polymer is manufactured by polymerization of the methacrylic acid-containing composition according to the fourth embodiment can be reduced, thereby preventing adverse effects on the physical properties of the polymer. B The lower limit is more preferably 10 μmol / L or more, even more preferably 100 μmol / L or more, particularly preferably 1500 μmol / L or more, and especially preferably 2000 μmol / L or more. B The upper limit is more preferably 45,000 μmol / L or less, even more preferably 40,000 μmol / L or less, particularly preferably 35,000 μmol / L or less, especially preferably 30,000 μmol / L or less, and most preferably 25,000 μmol / L or less.

[0276] (Concentration of methacrylic acid) The concentration of methacrylic acid in the methacrylic acid-containing composition according to the fourth embodiment is 98.00 to 99.99% by mass. By having a methacrylic acid concentration of 98.00% by mass or higher, the amount of impurities produced when a methacrylic acid polymer is manufactured by polymerization of the methacrylic acid-containing composition according to the fourth embodiment can be reduced, and adverse effects on the physical properties of the polymer can be prevented. Furthermore, by having a methacrylic acid concentration of 99.99% by mass or lower, purification costs can be reduced. The lower limit of the methacrylic acid concentration is more preferably 98.50% or higher, even more preferably 99.00% or higher, particularly preferably 99.50% or higher, and most preferably 99.80% by mass or higher.

[0277] (Component C) The methacrylic acid-containing composition according to the fourth embodiment may further contain component C, which is another compound, as long as the concentration of methacrylic acid satisfies 98.00 to 99.99% by mass. Component C may include impurities generated during the production of methacrylic acid. For example, methacrylic acid may contain diacetyl as an impurity, but from the viewpoint of reducing the coloration of the methacrylic acid-containing composition, the concentration of diacetyl is preferably 55 μmol / L, more preferably 20 μmol / L or less, even more preferably 10 μmol / L or less, and particularly preferably 1 μmol / L or less.

[0278] (Analysis of methacrylic acid-containing compositions) The presence of component A4, component B, component C, and water in a methacrylic acid-containing composition can be confirmed, for example, by GC-MS measurement. If the GC-MS chart of the methacrylic acid-containing composition shows a peak at the same retention time as the component A4 standard, and the m / z value detected in the mass spectrum of that peak matches the exact mass of component A4, then the methacrylic acid-containing composition can be determined to contain component A4. If a standard of component A4 is unavailable, the peak can be determined to be component A4 if the mass spectrum pattern of the peak appearing in the GC-MS chart of the methacrylic acid-containing composition matches the mass spectrum pattern of component A4 recorded in a mass spectrum database. In other words, the methacrylic acid-containing composition can be determined to contain component A4. Examples of mass spectrum databases include NIST20, NIST17, NIST14, and NIST14s. Furthermore, if the volatility is low and detection by GC-MS is not possible, detection can be performed using LC-MS. The presence of component B, component C, and water can also be confirmed by a similar method. Furthermore, the concentration of methacrylic acid can be calculated, for example, by performing a GC-FID measurement of the methacrylic acid-containing composition, quantifying it using the area percentage method, and correcting it using the moisture concentration quantified with a Karl Fischer moisture meter. The concentration of component A4 can be calculated, for example, by performing a GC measurement of the methacrylic acid-containing composition and quantifying it using the internal standard method. If a standard sample of component A4 cannot be obtained and it cannot be quantified by the internal standard method, the concentration of component A4 can be calculated using the following formula by performing a GC-FID measurement of any organic compound with a known concentration under the same conditions as the methacrylic acid-containing composition.

[0279]

number

[0280] 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 A4is the peak area of ​​component A4, S is the peak area of ​​the organic compound with a known concentration, and M is the concentration (μmol / L) of the organic compound with a known concentration.

[0281] If the volatility is low and quantification by GC measurement is not possible, quantification can be performed using chromatographic methods such as LC. The concentrations of components B and C can also be calculated using the same method as for component A4 described above. Furthermore, the presence of water in the methacrylic acid-containing composition, and its concentration, can be confirmed by the Karl Fischer method.

[0282] [Methacrylic acid-containing composition production method] A method for producing a methacrylic acid-containing composition according to the fourth embodiment is to add component A4 and component B to methacrylic acid. The methacrylic acid may be a commercially available product, or methacrylic acid produced by known methods such as the acetone cyanohydrin (ACH) method or the C4 direct oxidation method may be used. Component A4 and component B may be commercially available products, or synthesized by known methods may be used. When using methacrylic acid produced by known methods such as the acetone cyanohydrin (ACH) method or the C4 direct oxidation method, component A4 or component B may be added as a raw material or during the manufacturing process to produce the methacrylic acid-containing composition. Furthermore, if component A4 or component B is produced as a by-product in the methacrylic acid manufacturing process, the methacrylic acid-containing composition may be produced by leaving a portion of the produced component A4 or component B.

[0283] [Methods for evaluating storage stability and thermal stability] The methacrylic acid-containing composition according to the fourth embodiment exhibits high quality stability during storage. Methods for evaluating the quality stability of the methacrylic acid-containing composition during storage include, for example, actually storing the methacrylic acid-containing composition for a long period and confirming the decrease in polymerization inhibitor. Alternatively, from the viewpoint of ease of operation, a method of heating the methacrylic acid-containing composition for a short time and confirming the decrease in polymerization inhibitor may 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 this invention, the quality stability of the methacrylic acid-containing composition during storage was evaluated by the decrease in polymerization inhibitor when the methacrylic acid-containing composition was stored at 25°C for 21 days.

[0284] [Methacrylic acid ester production method] The method for producing methacrylic acid ester according to the fourth embodiment includes a step of esterifying the methacrylic acid-containing composition according to the fourth embodiment. The alcohol reacted with the methacrylic acid-containing composition is not particularly limited and includes, for example, methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, etc. The resulting methacrylic acid esters include, for example, methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, butyl methacrylate, isobutyl methacrylate, etc. The esterification reaction can be carried out in the presence of an acidic catalyst such as a sulfonic acid type cation exchange resin. The temperature during the esterification reaction is preferably 50 to 200°C. The pressure during the esterification reaction, the position of the catalyst in the reactor, and the proportion of the catalyst in the reactor are not particularly limited, and commonly used configurations can be applied.

[0285] [Methacrylic acid polymer production method according to the fourth embodiment] A method for producing a methacrylic acid polymer according to the fourth embodiment includes a step of polymerizing a polymerizable composition containing the methacrylic acid-containing composition according to the fourth embodiment.

[0286] The polymerizable composition may optionally contain monomers copolymerizable with methacrylic acid and other additives.

[0287] Examples of monomers copolymerizable with methacrylic acid include the following: Methacrylic acid esters such as methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, iso-butyl methacrylate, tert-butyl methacrylate, 2-ethylhexyl methacrylate, phenyl methacrylate, or benzyl methacrylate; Acrylic acid esters such as methyl acrylate, ethyl acrylate, n-butyl acrylate, iso-butyl acrylate, tert-butyl acrylate, or 2-ethylhexyl acrylate; Unsaturated carboxylic acids such as acrylic acid, maleic acid, or itaconic acid; Unsaturated carboxylic acid anhydrides such as maleic anhydride or itaconic anhydride; Maleimides such as N-phenylmaleimide or N-cyclohexylmaleimide; 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, or 2-hydroxypropyl methacrylate, or other hydroxyl group-containing vinyl monomers; Vinyl esters such as vinyl acetate or vinyl benzoate; Vinyl chloride, vinylidene chloride, and their derivatives; Nitrogen-containing vinyl monomers such as methacrylamide or acrylonitrile; Epoxy group-containing monomers such as glycidyl acrylate or glycidyl methacrylate; Aromatic vinyl monomers such as styrene or α-methylstyrene; Alkane diol 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; 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; Vinyl monomers having two or more ethylenically unsaturated bonds in their molecules, such as divinylbenzene; Unsaturated polyester prepolymer obtained from at least one polycarboxylic acid containing an ethylenically unsaturated polycarboxylic acid and at least one diol; A vinyl ester prepolymer obtained by modifying the terminals of epoxy groups with acrylic.

[0288] Among the above, the monomer copolymerizable with methacrylic acid is preferably at least one selected from the group consisting of methacrylic acid esters and acrylic acid esters. The monomer copolymerizable with methacrylic acid is more preferably a methacrylic acid ester, and particularly preferably methyl methacrylate.

[0289] The monomer copolymerizable with methacrylic acid may be one type or two or more types. Furthermore, if component A4 is a monomer copolymerizable with methacrylic acid, component A4 may be used as the monomer copolymerizable with methacrylic acid, or a monomer copolymerizable with methacrylic acid may be used separately from component A4.

[0290] In the polymerizable composition, the content of monomers copolymerizable with methacrylic acid is preferably 50.00 to 99.99 parts by mass per 100 parts by mass of the polymerizable composition. The lower limit of the content of monomers copolymerizable with methacrylic acid is more preferably 60 parts by mass or more, even more preferably 70 parts by mass or more, particularly preferably 80 parts by mass or more, and most preferably 90 parts by mass or more, per 100 parts by mass of the polymerizable composition. The upper limit of the content of monomers copolymerizable with methacrylic acid is more preferably 99.9 parts by mass or less, and even more preferably 99 parts by mass or less, per 100 parts by mass of the polymerizable composition.

[0291] Other additives include polymerization initiators. The polymerizable composition may also contain, as needed, chain transfer agents, mold release agents, lubricants, plasticizers, antioxidants, antistatic agents, light stabilizers, UV absorbers, flame retardants, flame retardant aids, polymerization inhibitors, fillers, pigments, dyes, silane coupling agents, leveling agents, defoamers, fluorescent agents, etc. The other additives may be one type or two or more types.

[0292] Examples of polymerization initiators include the following: 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(cyclohexanecarbonitride), and dimethyl-2,2'-azobisisobutyrate; Benzoyl peroxide, 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane, 1,1-bis(t-butylperoxy)cyclohexane, 1,1-bis(t-butylperoxy)-3,5,5-trimethylcyclohexane, t-butylperoxy-2-ethylhexanoate, t-butylperoxyisobutyrate, t-butylperoxybenzoate, t-hexylperoxybenzoate, t-butylperoxyisopropyl monocarbonate, t-butylperoxy-3,5,5-trimethylhexanoate, t-butylperoxylaurate, t-butylperoxyacetate, t-hexylperoxyisopropyl monocarbonate, t-hexyl peroxy Organic peroxides such as -oxy-2-ethylhexanoate, t-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 peroxyisononate, 1,1,2-trimethylpropyl peroxyisononate, di-t-butyl peroxide, di-t-hexyl peroxide, lauroyl peroxide, and dilauroyl peroxide; Persulfate compounds such as potassium persulfate; A redox polymerization initiator.

[0293] Among the above, from the viewpoint of storage stability and reactivity with methacrylic acid and copolymerizable monomers, the polymerization initiator is preferably at least one selected from the group consisting of azo compounds and organic peroxides. The amount of polymerization initiator used is preferably 0.0001 to 1 part by mass per 100 parts by mass of methacrylic acid and monomers copolymerizable with methacrylic acid.

[0294] Polymerization methods for polymerizable compositions include, for example, bulk polymerization, solution polymerization, emulsion polymerization, and suspension polymerization. The polymerization temperature is preferably 125 to 210°C. This allows for obtaining an appropriate polymerization rate. The lower limit of the polymerization temperature is more preferably 130°C or higher, and the upper limit is more preferably 180°C or lower. The polymerization time is not particularly limited and can be, for example, 0.5 to 24 hours.

[0295] [Methacrylic acid-containing composition according to the fifth embodiment] The methacrylic acid-containing composition according to 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.

[0296] [ka]

[0297] In the above equation (51), R 1e and R 2e Each of these 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 R represents a hydrogen atom, alkyl group, alkenyl group, aryl group, hydroxyl group, alkoxy group, amino group, alkylthio group, or arylthio group. 1e and R 2e , R 2e and R 3e , R 3e and R 1e They may each be connected to each other to form a ring. However, R 1e and R 2e The total number of carbon atoms is 2 or more. Furthermore, the methacrylic acid-containing composition may also contain other compounds (component C) or water, as long as the concentration of methacrylic acid satisfies 98.00 to 99.99% by mass. Each item will be explained in detail below.

[0298] (Methacrylic acid) The methacrylic acid-containing composition according to the fifth embodiment contains methacrylic acid. Methacrylic acid can be produced, for example, as a by-product of the acetone cyanohydrin (ACH) process or as an intermediate of the C4 direct oxidation process. The methacrylic acid contained in the methacrylic acid-containing composition is preferably produced by the C4 direct oxidation process, and more preferably produced by the C4 direct oxidation process using biomass-derived isobutanol as a starting material.

[0299] (Ingredient A5) The methacrylic acid-containing composition according to the fifth embodiment contains a compound represented by formula (51) (component A5). "α-hydrogen" refers to a hydrogen atom bonded to a carbon atom adjacent to a 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.

[0300] Methacrylic acid is known to polymerize due to radicals generated during storage, and a polymerization inhibitor (component B) is added to prevent polymerization. Component B has a polymerization inhibitory function by trapping radicals generated during the storage of methacrylic acid, but because the polymerization inhibitor decomposes into other compounds when trapping radicals, the concentration of component B in the methacrylic acid-containing composition gradually decreases during storage, and the polymerization inhibitory function gradually deteriorates. Furthermore, the amount of unwanted decomposition products generated when component B traps radicals gradually increases. An example of a radical generated during the storage of methacrylic acid is the hydroxyl radical, which is generated when oxygen molecules absorb ultraviolet light from sunlight. Component A5 can trap the radical intermediate generated by the reaction of hydroxyl radicals and methacrylic acid, and can convert the intermediate back into methacrylic acid. Therefore, the amount of radicals that component B needs to trap is reduced, and the decrease in the concentration of component B can be suppressed. Furthermore, if the methacrylic acid composition contains carboxylic acids such as propionic acid or acrylic acid as impurities, the concentration of these carboxylic acids decreases during storage. This is presumed to be due to decomposition by decarboxylation. Since component A5 acts as a proton donor, it can donate protons to the anionic intermediate produced by the decarboxylation reaction, and is therefore presumed to promote the decarboxylation reaction.

[0301] The molecular weight of component A5 is preferably 1000 or less. By having a molecular weight of 1000 or less, the number of α-hydrogen atoms per unit mass in component A5 can be increased, so that the effects of the present invention can be obtained with a small mass. The molecular weight of component A5 is more preferably 800 or less, even more preferably 600 or less, and particularly preferably 400 or less.

[0302] R in equation (51) 1e and R 2e Each of these 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, and an alkylamino group. 1e and R 2e They may be the same or different. Also, R in formula (51) above 3e R represents a hydrogen atom, alkyl group, alkenyl group, aryl group, hydroxyl group, alkoxy group, amino group, alkylthio group, or arylthio group. 3e and R 1e , and R 3e and R 2e They may be the same or different. Also, R 1e and R 2e , R 2e and R 3e , R 3e and R 1e These may be connected to each other to form a ring.

[0303] Generally, the α-hydrogen of component A5 has the property of reacting with anions and radicals, but its reactivity may decrease depending on the type of substituent it has. 1e , R 2e and R 3eWhen the above conditions are met, the reactivity of the α-hydrogen of component A5 with anions and radicals is maintained, and therefore the effects of the present invention can be obtained. 1e and R 2e Preferably, the substituents 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 alkylthio group having 1 to 5 carbon atoms, an arylthio group having 6 to 10 carbon atoms, or an alkylamino group having 0 to 6 carbon atoms. Because these substituents are highly stable, they prevent component A5 from changing into other compounds during storage. Furthermore, their low electron-donating ability improves the acidity of the α-hydrogen of component A5. 1e and R 2e It is more preferably a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, an aryl group having 6 to 12 carbon atoms, 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, or an alkylamino group having 0 to 6 carbon atoms; it is even more preferably a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, an aryl group having 6 to 12 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an alkylamino group having 0 to 6 carbon atoms; it is particularly preferably a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an alkylamino group having 0 to 6 carbon atoms; it is especially preferably a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an s-butyl group, an isobutyl group, a hydroxyl group, a methoxy group, a cyclohexyl group, or an N,N-dimethylamino group; and it is most preferably a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, a hydroxyl group, a methoxy group, a cyclohexyl group, or an N,N-dimethylamino group.

[0304] Also, R 3eIt is more preferable that the substituents 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, an alkylthio group having 1 to 5 carbon atoms, or an arylthio group having 6 to 10 carbon atoms. Since these substituents are highly stable, they can prevent component A5 from changing into other compounds during storage. 3e It is more preferably a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, a hydroxyl group, or an alkoxy group having 1 to 6 carbon atoms, or an amino group having 0 to 6 carbon atoms; even more preferably a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, an amino group having 0 to 6 carbon atoms, or a hydroxyl group; particularly preferably a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, or an isopropyl group, an isopropenyl group, or a hydroxyl group; and most preferably a hydrogen atom, a methyl group, an isopropyl group, or a hydroxyl group.

[0305] Alkyl groups are linear (linear or branched) alkyl groups or cyclic alkyl groups. In the case of linear alkyl groups, those having 1 to 20 carbon atoms are preferred, those having 1 to 10 carbon atoms are more preferred, and those having 1 to 5 carbon atoms are even more preferred. Examples of linear alkyl groups include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, s-butyl group, t-butyl group, n-pentyl group, isopentyl group, hexyl group, octyl group, decyl group, hydroxymethyl group, 1-hydroxyethyl group, 2-hydroxyethyl group, etc., with methyl group, ethyl group, n-propyl group, and isopropyl group being preferred. In the case of cyclic alkyl groups, those having 3 to 20 carbon atoms are preferred, those having 4 to 10 carbon atoms are more preferred, and those having 5 to 7 carbon atoms are even more preferred. Examples of cyclic alkyl groups include cyclopentyl group, cyclohexyl group, and cyclooctyl group.

[0306] The alkenyl group is either a linear (linear or branched) alkenyl group or a cyclic alkenyl group. In the case of a linear alkenyl group, a linear alkenyl group having 2 to 20 carbon atoms is preferred, a linear alkenyl group having 2 to 10 carbon atoms is more preferred, and a linear alkenyl group having 2 to 5 carbon atoms is even more preferred. Examples of linear alkenyl groups include vinyl, 1-propenyl, isopropenyl, 2-butenyl, 1,3-butadienyl, 2-pentenyl, and 2-hexenyl groups. 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 even more preferred. Examples of cyclic alkenyl groups include cyclopentenyl and cyclohexenyl groups.

[0307] 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 even more preferably an alkoxy group having 1 to 6 carbon atoms. Examples of alkoxy groups include methoxy, ethoxy, butoxy, and phenoxy groups.

[0308] The amino group includes an amino group (-NH2) (0 carbon atoms) with no substituents on the nitrogen atom, and an amino group in which some or all of the hydrogen atoms bonded to the nitrogen atom are substituted with carbon atoms. The number of carbon atoms in the amino group in which some 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 even more preferably 1 to 6. Examples of amino groups include an unsubstituted amino group (-NH2), methylamino group, ethylamino group, propylamino group, butylamino group, dimethylamino group, diethylamino group, anilino group, toluidino group, anisidino group, diphenylamino group, and N-methyl-N-phenylamino group.

[0309] 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 even more preferably an alkylthio group having 1 to 5 carbon atoms. Examples of alkylthio groups include methylthio group, ethylthio group, propylthio group, isopropylthio group, and the like.

[0310] 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 even more preferably an arylthio group having 6 to 10 carbon atoms. Examples of arylthio groups include phenylthio groups and tolylthio groups.

[0311] 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 heteroaryl groups containing oxygen, nitrogen, sulfur, etc. Examples of aryl groups include phenyl, mesityl, naphthyl, 2-methylphenyl, 3-methylphenyl, 4-methylphenyl, 2,3-dimethylphenyl, 2,4-dimethylphenyl, 2,5-dimethylphenyl, 2,6-dimethylphenyl, 2-ethylphenyl, isoxazolyl, isothiazolyl, imidazolyl, oxazolyl, thiazolyl, thiadiazolyl, thienyl, triazolyl, tetrazolyl, pyridyl, pyrazinyl, pyrimidinyl, pyridadinyl, pyrazolyl, pyrrolyl, furyl, fluzanyl, isoquinolyl, isoindolyl, indolyl, quinolyl, pyridothiazolyl, benzimidazolyl, benzoxazolyl, benzothiazolyl, benzotriazolyl, benzofuranyl, imidazopyridinyl, triazopyridinyl, and prinyl groups.

[0312] R 1e and R 2e , R 2e and R 3e , R 3e and R 1e They may each be connected to each other to form a ring. 1e and R 2eExamples of compounds in which these molecules are linked to form a ring include cyclohexanecarboxylic acid, methyl cyclohexanecarboxylic acid, cyclopentanecarboxylic acid, and methyl cyclopentanecarboxylic acid. 2e and R 3e Compounds in which R is linked to form a ring, and 3e and R 1e Examples of compounds in which these molecules are 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.

[0313] Among the compounds that satisfy the above conditions, from the viewpoint of quality stability during storage of methacrylic acid-containing compositions, component A5 includes isobutyric acid, isovaleric acid, 2-methylbutyric acid, acetonylacetone, 3-methyl-3-buten-2-one, isobutyraldehyde, cyclohexanecarboxylic acid, 2-methoxypropionic acid, N,N-dimethylglycine, malonic acid, methylthioacetic acid, 3-butenic acid, butyric acid, palmitic acid, stearic acid, methyl isobutyrate, ethyl isobutyrate, isobutyl isobutyrate, isoamyl isobutyrate, phenyl isobutyrate, methyl butyrate, methyl isovalerate, methylisopropyl ketone, 3-hexen-2-one, 2,5-dimethyl-2-cyclopenten-1-one, 2-methyl-5-isopropyl-1-cyclohexanone, 2-acetylfuran, butyraldehyde, 2-methylbutyraldehyde, 3-methylbutyraldehyde, (R)-(-)-3-hydroxyisobutyric acid, cyclopentyl acetone. Isobutan carboxylic acid, α-methyl-δ-valerolactone, or α-methyl-γ-butyrolactone are preferred, isobutyric acid, isovaleric acid, 2-methylbutyric acid, acetonylacetone, 3-methyl-3-buten-2-one, isobutyraldehyde, cyclohexanecarboxylic acid, 2-methoxypropionic acid, N,N-dimethylglycine, malonic acid, methylthioacetic acid, 3-butenic acid, and methylisopropenyl ketone are more preferred, isobutyric acid, isovaleric acid, 2-methylbutyric acid, 2-methoxypropionic acid, N,N-dimethylglycine, acetonylacetone, 3-methyl-3-buten-2-one, isobutyraldehyde, and methylisopropenyl ketone are even more preferred, and isobutyric acid, isovaleric acid, 2-methylbutyric acid, acetonylacetone, isopropenylmethyl ketone, isobutyraldehyde, cyclohexanecarboxylic acid, 2-methoxypropionic acid, and N,N-dimethylglycine are particularly preferred.

[0314] Component A5 may be one type or two or more types.

[0315] (Component B) The methacrylic acid-containing composition according to the fifth embodiment contains a polymerization inhibitor (component B). In this specification, a polymerization inhibitor means a compound that has the function of suppressing the polymerization reaction of methacrylic acid. Examples of polymerization inhibitors include phenolic compounds, quinone compounds, nitrobenzene compounds, N-oxyl compounds, amine compounds, phosphorus-containing compounds, sulfur-containing compounds, iron-containing compounds, copper-containing compounds, and manganese-containing compounds. By including component B, the polymerization reaction of methacrylic acid by a radical polymerization mechanism can be suppressed during storage. Furthermore, as mentioned above, the coexistence of component A5 and component B can efficiently suppress the decrease of component B.

[0316] Examples of polymerization inhibitors that are phenolic compounds include alkylphenols, hydroxyphenols, aminophenols, nitrophenols, nitrosophenols, alkoxyphenols, and tocopherols.

[0317] Examples of alkylphenols include o-cresol, m-cresol, p-cresol, 2-t-butyl-4-methylphenol, 2,4-dimethyl-6-t-butylphenol, 2,6-di-t-butyl-4-methylphenol, 2-t-butylphenol, 4-t-butylphenol, 2,4-di-t-butylphenol, 2-methyl-4-t-butylphenol, 4-t-butyl-2,6-dimethylphenol, 2,2'-methylenebis(6-t-butyl-4-methylphenol), 2,2'-methylenebis(4-ethyl-6-t-butylphenol), 4,4'-thiobis(3-methyl-6-t-butylphenol), and 3,5-di-t-butyl-4-hydroxytoluene.

[0318] Examples of hydroxyphenols include hydroquinone, 2-methylhydroquinone, 2-t-butylhydroquinone, 2,5-di-t-butylhydroquinone, 2,6-di-t-butylhydroquinone, 2,5-di-t-amylhydroquinone, 2-t-butylmethoxyhydroquinone, 2,3,5-trimethylhydroquinone, 2,5-dichlorohydroquinone, 1,2-dihydroxybenzene, 2-acetylhydroquinone, 4-methylcatechol, 4-t-butylcatechol, 2-methylresorcinol, 4-methylresorcinol, and 2,3-dihydroxyacetophenone.

[0319] Examples of aminophenols include o-aminophenol, m-aminophenol, p-aminophenol, 2-(N,N-dimethylamino)phenol, and 4-(ethylamino)phenol.

[0320] Examples of nitrophenols include o-nitrophenol, m-nitrophenol, p-nitrophenol, and 2,4-dinitrophenol.

[0321] Examples of nitrosophenols include o-nitrosophenol, m-nitrosophenol, p-nitrosophenol, and α-nitroso-β-naphthol.

[0322] Examples of alkoxyphenols include 2-methoxyphenol, 2-ethoxyphenol, 2-isopropoxyphenol, 2-t-butoxyphenol, 4-methoxyphenol, 4-ethoxyphenol, 4-propoxyphenol, 4-butoxyphenol, 4-t-butoxyphenol, 4-heptoxyphenol, hydroquinone monobenzyl ether, t-butyl-4-methoxyphenol, di-t-butyl-4-methoxyphenol, pyrogallol-1,2-dimethyl ether, and hydroquinone monobenzoate.

[0323] Examples of tocopherols include α-tocopherol and 2,3-dihydro-2,2-dimethyl-7-hydroxybenzofuran.

[0324] Examples of polymerization inhibitors that are quinone compounds 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.

[0325] Examples of polymerization inhibitors that are nitrobenzene compounds include nitrobenzene, o-dinitrobenzene, m-dinitrobenzene, p-dinitrobenzene, 2,4-dinitrotoluene, dinitrojulene, and 2,2-diphenyl-1-picrylhydrazyl.

[0326] Examples of polymerization inhibitors that are N-oxyl compounds include 4-hydroxy-2,2,6,6-tetramethyl-piperidine-N-oxyl, 4-oxo-2,2,6,6-tetramethyl-piperidine-N-oxyl, 4-acetoxy-2,2,6,6-tetramethyl-piperidine-N-oxyl, 2,2,6,6-tetramethyl-piperidine-N-oxyl, piperidine-1-oxyl, 4-(dimethylamino)-2,2,6,6-tetramethyl-piperidine-N-oxyl, 4-amino-2,2,6,6-tetramethyl-piperidine-N-oxyl, 4-ethanoloxy-2,2,6,6-tetramethyl-piperidine-N-oxyl, and 4-benzoyloxy-2,2,6,6-tetramethylpiperidine-N-oxyl Examples include 2,2,5,5-tetramethyl-piperidine-N-oxyl, 3-amino-2,2,5,5-tetramethyl-piperidine-N-oxyl, 4,4',4''-tris(2,2,6,6-tetramethyl-piperidine-N-oxyl) phosphite, 3-oxo-2,2,5,5-tetramethylpyrrolidine-N-oxyl, pyrrolidine-1-oxyl, 2,2,5,5-tetramethyl-1-oxa-3-azacyclopentyl-3-oxy, 2,2,5,5-tetramethyl-3-pyrrolinyl-1-oxy-3-carboxylic acid, 2,2,3,3,5,5,6,6-octamethyl-1,4-diazacyclohexyl-1,4-dioxy, di-tert-butyl nitroxide, di-tert-amyl nitroxide, etc.

[0327] Examples of polymerization inhibitors that are amine compounds include N,N-diphenylamine, alkylated diphenylamine, 4,4'-dicumyl-diphenylamine, 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, and each group consists of 1 to 4 carbon atoms independently of each other, 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, Examples include N,N'-di-2-naphthyl-p-phenylenediamine, N,N-diethylhydroxylamine, 1,4-benzenediamine, N-(1,4-dimethylpentyl)-N'-phenyl-1,4-benzenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-1,4-benzenediamine, 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline, 2,2,4-trimethyl-1,2-dihydroquinoline polymer, aldol-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, and 1-hydroxy-4-benzoyloxy-2,2,6,6-tetramethylpiperidine.

[0328] Examples of polymerization inhibitors containing phosphorus include triphenylphosphine, triphenyl phosphite, triethyl phosphite, tris(isodecyl) phosphite, tris(tridecyl) phosphite, phenyldiisooctyl phosphite, phenyldiisodecyl phosphite, phenyldi(tridecyl) phosphite, diphenylisooctyl phosphite, diphenylisodecyl phosphite, diphenyltridecyl phosphite, phosphonic acid [1,1-diphenyl-4,4'-diylbistetrakis-2,4-bis(1,1-dimethylethyl)phenyl]ester, tris(nonylphenyl) phosphite, 4,4'-isopropylidenediphenolalkyl phosphite, tris(2,4-di-tert-butylphenyl) phosphite, tris(biphenyl) phosphite, and distearylpentaerythritol. Examples include di(2,4-di-tert-butylphenyl)pentaerythritol diphosphite, di(nonylphenyl)pentaerythritol diphosphite, phenylbisphenol A pentaerythritol diphosphite, tetra(tridecyl)-4,4'-butylidenebis(3-methyl-6-tert-butylphenol) diphosphite, hexa(tridecyl)-1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane triphosphite, 3,5-di-tert-butyl-4-hydroxybenzyl phosphate diethyl ester, sodium-bis(4-tert-butylphenyl) phosphate, sodium-2,2'-methylene-bis(4,6-di-tert-butylphenyl) phosphate, and 1,3-bis(diphenoxyphosphonyloxy)benzene.

[0329] Examples of polymerization inhibitors containing sulfur include diphenyl sulfide, phenothiazine, 3-oxofhenothiazine, 5-oxofhenothiazine, phenothiazine dimers, 1,4-dimercaptobenzene, 1,2-dimercaptobenzene, 2-mercaptophenol, 4-mercaptophenol, 2-(methylthio)phenol, 3,7-bis(dimethylamino)phenothiazinium chloride, and elemental sulfur.

[0330] Examples of polymerization inhibitors that contain iron include iron(III) chloride.

[0331] Examples of polymerization inhibitors containing copper include copper dimethyldithiocarbamate, copper diethyldithiocarbamate, copper dibutyldithiocarbamate, copper salicylate, copper acetate, copper thiocyanate, copper nitrate, copper chloride, copper carbonate, copper hydroxide, copper acrylate, and copper methacrylate.

[0332] Examples of manganese-containing polymerization inhibitors include manganese dialkyldithiocarbamate (the alkyl group is one of methyl, ethyl, propyl, or butyl groups, and may be the same or different), manganese diphenyldithiocarbamate, manganese formate, manganese acetate, manganese octanoate, manganese naphthenate, manganese permanganate, and manganese salts of ethylenediaminetetraacetic acid.

[0333] Among the above, from the viewpoint of quality stability during storage of the methacrylic acid-containing composition, component B is preferably at least one polymerization inhibitor selected from the group consisting of phenolic compounds, N-oxyl compounds, amine compounds, phosphorus-containing compounds, and sulfur-containing compounds. For example, it is preferably at least one polymerization inhibitor selected from the group consisting of hydroquinone, 4-methoxyphenol, 2,4-dimethyl-6-t-butylphenol, 2,6-di-t-butyl-4-methylphenol, 4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl, N,N-diphenylamine, N-nitrosodiphenylamine, triphenyl phosphite, and phenothiazine. Component B is more preferably a phenolic compound, for example at least one polymerization inhibitor selected from the group consisting of hydroquinone, 4-methoxyphenol, 2,4-dimethyl-6-t-butylphenol, and 2,6-di-t-butyl-4-methylphenol. Component B is particularly preferably at least one polymerization inhibitor selected from the group consisting of hydroquinone and 4-methoxyphenol.

[0334] Component B may be one type or two or more types. If a methacrylic acid-containing composition contains a compound that corresponds to both component A5 and component B, that compound shall be considered as component B. In other words, the methacrylic acid-containing composition must contain a component A5 other than that compound. If two or more compounds that correspond to both component A5 and component B are contained, the compound with the highest molar concentration in the methacrylic acid composition shall be considered as component B, and the other compounds shall be considered as component A5.

[0335] (Concentrations of component A5 and component B) The concentration of component A5 is M A5 (μmol / L), the concentration of component B is M B When given (μmol / L), M B / M A5 It is preferable that it is between 0.005 and 100. From the viewpoint of the efficiency of suppressing pyruvate production, M B / M A5A lower limit of 0.05 or higher and an upper limit of 10 or lower are more preferable.

[0336] M A5 The concentration is preferably 1 to 40,000 μmol / L. A5 When the concentration is 1 μmol / L or higher, the effect of suppressing the decomposition of polymerization inhibitors can be sufficiently obtained. A5 By having a concentration of 40,000 μmol / L or less, the amount of impurities produced when a methacrylic acid polymer is manufactured by polymerization of the methacrylic acid-containing composition according to the fifth embodiment can be reduced, and adverse effects on the physical properties of the polymer can be prevented. A5 The lower limit is more preferably 10 μmol / L or higher, even more preferably 30 μmol / L or higher, even more preferably 50 μmol / L or higher, and even more preferably 55 μmol / L or higher. A3 The upper limit is more preferably 3000 μmol / L or less, even more preferably 25000 μmol / L or less, and particularly preferably 20000 μmol / L or less.

[0337] M B The concentration is preferably 1 to 50,000 μmol / L. B By having a concentration of 1 μmol / L or higher, the effect of suppressing the formation of methacrylic acid dimers and pyruvate can be sufficiently obtained. B By having a concentration of 50,000 μmol / L or less, the amount of impurities produced when a methacrylic acid polymer is manufactured by polymerization of the methacrylic acid-containing composition according to the fifth embodiment can be reduced, and adverse effects on the physical properties of the polymer can be prevented. B The lower limit is more preferably 10 μmol / L or more, even more preferably 100 μmol / L or more, particularly preferably 1500 μmol / L or more, and especially preferably 2000 μmol / L or more. B The upper limit is more preferably 45,000 μmol / L or less, even more preferably 40,000 μmol / L or less, particularly preferably 35,000 μmol / L or less, especially preferably 30,000 μmol / L or less, and most preferably 25,000 μmol / L or less.

[0338] (Concentration of methacrylic acid) The concentration of methacrylic acid in the methacrylic acid-containing composition according to the fifth embodiment is 98.00 to 99.99% by mass. By having a methacrylic acid concentration of 98.00% by mass or higher, the amount of impurities produced when a methacrylic acid polymer is manufactured by polymerization of the methacrylic acid-containing composition according to the fifth embodiment can be reduced, and adverse effects on the physical properties of the polymer can be prevented. Furthermore, by having a methacrylic acid concentration of 99.99% by mass or lower, purification costs can be reduced. The lower limit of the methacrylic acid concentration is more preferably 98.50% or higher, even more preferably 99.00% or higher, particularly preferably 99.50% or higher, and most preferably 99.80% by mass or higher.

[0339] (Component C) The methacrylic acid-containing composition according to the fifth embodiment may further contain component C, which is another compound, as long as the concentration of methacrylic acid satisfies 98.00 to 99.99% by mass. Component C may include impurities generated during the production of methacrylic acid. For example, methacrylic acid may contain diacetyl as an impurity, but from the viewpoint of reducing the discoloration of the methacrylic acid-containing composition, the concentration of diacetyl is preferably 55 μmol / L or less, more preferably 20 μmol / L or less, even more preferably 10 μmol / L or less, and particularly preferably 1 μmol / L or less.

[0340] (Analysis of methacrylic acid-containing compositions) The presence of component A5, component B, component C, and water in a methacrylic acid-containing composition can be confirmed, for example, by GC-MS measurement. If the GC-MS chart of the methacrylic acid-containing composition shows a peak at the same retention time as the standard of component A5, and the m / z value detected in the mass spectrum of that peak matches the exact mass of component A5, then the methacrylic acid-containing composition can be determined to contain component A5. If a standard of component A5 is not available, the peak can be determined to be the component A5 peak if the mass spectrum pattern of the peak appearing in the GC-MS chart of the methacrylic acid-containing composition matches the mass spectrum pattern of component A5 recorded in a mass spectrum database. In other words, the methacrylic acid-containing composition can be determined to contain component A5. Examples of mass spectrum databases include NIST20, NIST17, NIST14, and NIST14s. Furthermore, if the volatility is low and detection by GC-MS measurement is not possible, detection can be performed using LC-MS. The presence of component B, component C, and water can also be confirmed by a similar method. Furthermore, the concentration of methacrylic acid can be calculated, for example, by performing a GC-FID measurement of the methacrylic acid-containing composition, quantifying it using the area percentage method, and correcting it using the moisture concentration quantified with a Karl Fischer moisture meter. The concentration of component A5 can be calculated, for example, by performing a GC measurement of the methacrylic acid-containing composition and quantifying it using the internal standard method. If a standard sample of component A5 cannot be obtained and quantification cannot be performed by the internal standard method, the concentration of component A5 can be calculated using the following formula by performing a GC-FID measurement of any organic compound with a known concentration under the same conditions as the methacrylic acid-containing composition.

[0341]

number

[0342] Here, N is the number of carbon atoms in one molecule of an organic compound with a known concentration. A5 is the number of carbon atoms in one molecule of component A5, S A5is the peak area of ​​component A5, S is the peak area of ​​the organic compound with a known concentration, and M is the concentration (μmol / L) of the organic compound with a known concentration.

[0343] If the volatility is low and quantification by GC measurement is not possible, quantification can be performed using chromatographic methods such as LC. The concentrations of components B and C can also be calculated using the same method as for component A5 described above. Furthermore, the presence of water in the methacrylic acid-containing composition, and its concentration, can be confirmed by the Karl Fischer method.

[0344] [Methacrylic acid-containing composition production method] A method for producing a methacrylic acid-containing composition according to the fifth embodiment is to add component A5 and component B to methacrylic acid. The methacrylic acid may be a commercially available product, or methacrylic acid produced by known methods such as the acetone cyanohydrin (ACH) method or the C4 direct oxidation method may be used. Component A5 and component B may be commercially available products, or synthesized by known methods may be used. When using methacrylic acid produced by known methods such as the acetone cyanohydrin (ACH) method or the C4 direct oxidation method, component A5 or component B may be added as a raw material or during the manufacturing process to produce the methacrylic acid-containing composition. Furthermore, if component A5 or component B is produced as a by-product in the methacrylic acid manufacturing process, the methacrylic acid-containing composition may be produced by leaving a portion of the produced component A5 or component B.

[0345] [Methods for evaluating storage stability and thermal stability] The methacrylic acid-containing composition according to the fifth embodiment exhibits high quality stability during storage. Methods for evaluating the quality stability of the methacrylic acid-containing composition during storage include, for example, actually storing the methacrylic acid-containing composition for a long period and confirming the decrease in polymerization inhibitor. Alternatively, from the viewpoint of ease of operation, a method of heating the methacrylic acid-containing composition for a short time and confirming the decrease in polymerization inhibitor may 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 methacrylic acid-containing composition during storage was evaluated by the decrease in polymerization inhibitor when the methacrylic acid-containing composition was stored at 25°C for 21 days.

[0346] [Methacrylic acid ester production method] The method for producing methacrylic acid ester according to the fifth embodiment includes a step of esterifying the methacrylic acid-containing composition according to the fifth embodiment. The alcohol reacted with the methacrylic acid-containing composition is not particularly limited and includes, for example, methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, etc. The resulting methacrylic acid esters include, for example, methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, butyl methacrylate, isobutyl methacrylate, etc. The esterification reaction can be carried out in the presence of an acidic catalyst such as a sulfonic acid type cation exchange resin. The temperature during the esterification reaction is preferably 50 to 200°C. The pressure during the esterification reaction, the position of the catalyst in the reactor, and the proportion of the catalyst in the reactor are not particularly limited, and commonly used configurations can be applied.

[0347] [Methacrylic acid polymer production method according to the fifth embodiment] The method for producing a methacrylic acid polymer according to the present invention includes a step of polymerizing a polymerizable composition containing the methacrylic acid-containing composition according to the present invention.

[0348] The polymerizable composition may optionally contain monomers copolymerizable with methacrylic acid and other additives.

[0349] Examples of monomers copolymerizable with methacrylic acid include the following: Methacrylic acid esters such as ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, iso-butyl methacrylate, tert-butyl methacrylate, 2-ethylhexyl methacrylate, phenyl methacrylate, or benzyl methacrylate; Acrylic acid esters such as methyl acrylate, ethyl acrylate, n-butyl acrylate, iso-butyl acrylate, tert-butyl acrylate, or 2-ethylhexyl acrylate; Unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, or itaconic acid; Unsaturated carboxylic acid anhydrides such as maleic anhydride or itaconic anhydride; Maleimides such as N-phenylmaleimide or N-cyclohexylmaleimide; 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, or 2-hydroxypropyl methacrylate, or other hydroxyl group-containing vinyl monomers; Vinyl esters such as vinyl acetate or vinyl benzoate; Vinyl chloride, vinylidene chloride, and their derivatives; Nitrogen-containing vinyl monomers such as methacrylamide or acrylonitrile; Epoxy group-containing monomers such as glycidyl acrylate or glycidyl methacrylate; Aromatic vinyl monomers such as styrene or α-methylstyrene; Alkane diol 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; 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; Vinyl monomers having two or more ethylenically unsaturated bonds in their molecules, such as divinylbenzene; Unsaturated polyester prepolymer obtained from at least one polycarboxylic acid containing an ethylenically unsaturated polycarboxylic acid and at least one diol; A vinyl ester prepolymer obtained by modifying the terminals of epoxy groups with acrylic.

[0350] Among the above, the monomer copolymerizable with methacrylic acid is preferably at least one selected from the group consisting of methacrylic acid esters and acrylic acid esters. The monomer copolymerizable with methacrylic acid is more preferably a methacrylic acid ester, and methyl methacrylate is particularly preferred. The monomers copolymerizable with methacrylic acid may be one type or two or more types.

[0351] In the polymerizable composition, the content of monomers copolymerizable with methacrylic acid is preferably 50.00 to 99.99 parts by mass per 100 parts by mass of the polymerizable composition. The lower limit of the content of monomers copolymerizable with methacrylic acid is more preferably 60 parts by mass or more, even more preferably 70 parts by mass or more, particularly preferably 80 parts by mass or more, and most preferably 90 parts by mass or more, per 100 parts by mass of the polymerizable composition. The upper limit of the content of monomers copolymerizable with methacrylic acid is more preferably 99.9 parts by mass or less, and even more preferably 99 parts by mass or less, per 100 parts by mass of the polymerizable composition.

[0352] Other additives include polymerization initiators. The polymerizable composition may also contain, as needed, chain transfer agents, mold release agents, lubricants, plasticizers, antioxidants, antistatic agents, light stabilizers, UV absorbers, flame retardants, flame retardant aids, polymerization inhibitors, fillers, pigments, dyes, silane coupling agents, leveling agents, defoamers, fluorescent agents, etc. The other additives may be one type or two or more types.

[0353] Examples of polymerization initiators include the following: 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(cyclohexanecarbonitride), and dimethyl-2,2'-azobisisobutyrate; Benzoyl peroxide, 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane, 1,1-bis(t-butylperoxy)cyclohexane, 1,1-bis(t-butylperoxy)-3,5,5-trimethylcyclohexane, t-butylperoxy-2-ethylhexanoate, t-butylperoxyisobutyrate, t-butylperoxybenzoate, t-hexylperoxybenzoate, t-butylperoxyisopropyl monocarbonate, t-butylperoxy-3,5,5-trimethylhexanoate, t-butylperoxylaurate, t-butylperoxyacetate, t-hexylperoxyisopropyl monocarbonate, t-hexyl peroxy Organic peroxides such as -oxy-2-ethylhexanoate, t-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 peroxyisononate, 1,1,2-trimethylpropyl peroxyisononate, di-t-butyl peroxide, di-t-hexyl peroxide, lauroyl peroxide, and dilauroyl peroxide; Persulfate compounds such as potassium persulfate; A redox polymerization initiator.

[0354] Among the above, from the viewpoint of storage stability and reactivity with methacrylic acid and copolymerizable monomers, the polymerization initiator is preferably at least one selected from the group consisting of azo compounds and organic peroxides. The amount of polymerization initiator used is preferably 0.0001 to 1 part by mass per 100 parts by mass of methacrylic acid and monomers copolymerizable with methacrylic acid.

[0355] Polymerization methods for polymerizable compositions include, for example, bulk polymerization, solution polymerization, emulsion polymerization, and suspension polymerization. The polymerization temperature is preferably 125 to 210°C. This allows for obtaining an appropriate polymerization rate. The lower limit of the polymerization temperature is more preferably 130°C or higher, and the upper limit is more preferably 180°C or lower. The polymerization time is not particularly limited and can be, for example, 0.5 to 24 hours.

[0356] [Sixth aspect: Methacrylic acid-containing composition] The methacrylic acid-containing composition according to 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.

[0357] [ka]

[0358] In formula (61), R 1f , R 2f and R 3f Each of these 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 a monovalent group including an alkyl group, alkenyl group, aryl group, hydroxyl group, alkoxy group, amino group, or carbonyl group, an alkylthio group, or an arylthio group. However, R 1f =H and R 2f =H and R 3f =CH3 and R 4f Except when the case is =OH, i.e., 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. Furthermore, the methacrylic acid-containing composition may also contain other compounds (component C) or water, as long as the concentration of methacrylic acid satisfies 98.00 to 99.99% by mass. Each item will be explained in detail below.

[0359] (Methacrylic acid) The methacrylic acid-containing composition according to the sixth embodiment contains methacrylic acid. Methacrylic acid can be produced, for example, as a by-product of the acetone cyanohydrin (ACH) process or as an intermediate of the C4 direct oxidation process. The methacrylic acid contained in the methacrylic acid-containing composition is preferably produced by the C4 direct oxidation process, and more preferably produced by the C4 direct oxidation process using biomass-derived isobutanol as a starting material.

[0360] (Ingredient A6) The methacrylic acid-containing composition according to the sixth embodiment contains a compound represented by formula (61) (component A6). The coexistence of component A6 and component B, described later, can suppress the decomposition of polymerization inhibitors during storage of the methacrylic acid-containing composition. Furthermore, if the methacrylic acid-containing composition contains impurities such as acrylic acid or propionic acid, their decomposition can be promoted, thereby reducing the concentration of impurities. The reason for this is presumed to be as follows.

[0361] Methacrylic acid is known to polymerize due to radicals generated during storage, and a polymerization inhibitor (component B) is added to prevent polymerization. Component B has a polymerization inhibitory function by trapping radicals generated during the storage of methacrylic acid, but because the polymerization inhibitor decomposes into other compounds when trapping radicals, the concentration of component B in the methacrylic acid-containing composition gradually decreases during storage, and the polymerization inhibitory function gradually deteriorates. Furthermore, the amount of unwanted decomposition products generated by component B trapping radicals gradually increases. An example of a radical generated during the storage of methacrylic acid is the hydroxyl radical, which is generated when oxygen molecules absorb ultraviolet light from sunlight. Hydroxyl radicals also cause the production of pyruvate through the oxidation of methacrylic acid. Component A6 has a conjugated double bond and therefore absorbs ultraviolet light, and its absorption wavelength changes depending on the type of substituent. Component A6 can absorb ultraviolet light across a wide range of wavelengths. Therefore, when a methacrylic acid-containing composition contains component A6, ultraviolet light across a wide range of wavelengths is absorbed, and the generation of hydroxyl radicals is suppressed. Therefore, since the number of radicals that component B needs to trap is reduced, the decrease in the concentration of component B can be suppressed. Among various organic compounds that absorb ultraviolet light, component A6 has a molecular structure similar to methacrylic acid. Therefore, when polymers are manufactured using a methacrylic acid-containing composition as a raw material, the adverse effects of component A6 being included as an impurity can be reduced.

[0362] 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, so that the effects of the present invention can be obtained with a small mass. The molecular weight of component A6 is more preferably 800 or less, even more preferably 600 or less, and particularly preferably 400 or less.

[0363] R in equation (61) 1f , R 2f and R 3fEach of these 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. Also, in formula (61) above, R 4f R represents a monovalent group including an alkyl group, alkenyl group, aryl group, hydroxyl group, alkoxy group, amino group, or carbonyl group, an alkylthio group, or an arylthio group. 1f , R 2f , R 3f and R 4f These may be the same or different.

[0364] R 1f 、 R 2f 、 R 3f and R 4f When the above conditions are met, the π-conjugated system of component A6 is maintained, so it has the property of absorbing ultraviolet light of a wide range of wavelengths, and the effects of the present invention can be obtained. 1f , R 2f and R 3f Preferably, the substituent 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. Because these substituents are highly stable, they prevent component A6 from changing into other compounds during storage. Furthermore, when these substituents are present, a sufficient amount of ultraviolet light can be absorbed by one molecule of component A6. 1f , R 2f and R 3fIt is more preferably a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or an aryl group having 6 to 12 carbon atoms; it is even more preferably 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; it is particularly preferably a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, or an isopropyl group, or a phenyl group, and at least one of them is a methyl group, an ethyl group, an isopropyl group, or a phenyl group; and it is especially preferable that it is a hydrogen atom, a methyl group, an ethyl group, an isopropyl group, or a phenyl group, and at least one of them is a methyl group, an ethyl group, an isopropyl group, or a phenyl group.

[0365] Also, R 4f Preferably, the substituent is a monovalent group including 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, or a carbonyl group having 1 to 6 carbon atoms, or an alkylthio group having 1 to 5 carbon atoms or an arylthio group having 6 to 10 carbon atoms. Since these substituents are highly stable, they can prevent component A6 from changing into other compounds during storage. 4f It is more preferably 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 is particularly preferably 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 is especially preferably a methyl group, a hydroxyl group, a methoxy group, or an amino group. 4f When the structure is as described above, the quality stability of the methacrylic acid-containing composition during storage can be improved.

[0366] The alkyl group is a linear (linear or branched) alkyl group or a cyclic alkyl group. Alkyl groups having 1 to 20 carbon atoms are preferred, alkyl groups having 1 to 10 carbon atoms are more preferred, and alkyl groups having 1 to 5 carbon atoms are even more preferred. Examples of linear alkyl groups include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, s-butyl group, t-butyl group, n-pentyl group, isopentyl group, hexyl group, octyl group, decyl group, hydroxymethyl group, 1-hydroxyethyl group, and 2-hydroxyethyl group, with methyl group, ethyl group, n-propyl group, and isopropyl group being preferred. Examples of cyclic alkyl groups include cyclopentyl group, cyclohexyl group, and cyclooctyl group.

[0367] The alkenyl group is a linear (linear or branched) alkenyl group or a cyclic alkenyl group. Alkenyl groups with 2 to 20 carbon atoms are preferred, alkenyl groups with 2 to 10 carbon atoms are more preferred, and alkenyl groups with 2 to 5 carbon atoms are even more preferred. Examples of linear alkenyl groups include vinyl, 1-propenyl, isopropenyl, 2-butenyl, 1,3-butadienyl, 2-pentenyl, and 2-hexenyl groups. Examples of cyclic alkenyl groups include cyclopentenyl and cyclohexenyl groups.

[0368] 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 heteroaryl groups containing oxygen, nitrogen, sulfur, etc. Examples of aryl groups include phenyl, mesityl, naphthyl, 2-methylphenyl, 3-methylphenyl, 4-methylphenyl, 2,3-dimethylphenyl, 2,4-dimethylphenyl, 2,5-dimethylphenyl, 2,6-dimethylphenyl, 2-ethylphenyl, isoxazolyl, isothiazolyl, imidazolyl, oxazolyl, thiazolyl, thiadiazolyl, thienyl, triazolyl, tetrazolyl, pyridyl, pyrazinyl, pyrimidinyl, pyridadinyl, pyrazolyl, pyrrolyl, furyl, fluzanyl, isoquinolyl, isoindolyl, indolyl, quinolyl, pyridothiazolyl, benzimidazolyl, benzoxazolyl, benzothiazolyl, benzotriazolyl, benzofuranyl, imidazopyridinyl, triazopyridinyl, and prinyl groups.

[0369] 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 even more preferably an alkoxy group having 1 to 6 carbon atoms. Examples of alkoxy groups include methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, s-butoxy, t-butoxy, n-pentoxy, isopentoxy, and phenoxy groups.

[0370] The amino group includes an amino group (-NH2) (0 carbon atoms) with no substituents on the nitrogen atom, and an amino group in which some or all of the hydrogen atoms bonded to the nitrogen atom are substituted with carbon atoms. The number of carbon atoms in the amino group in which some 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 even more preferably 1 to 6. Examples of amino groups include an unsubstituted amino group (-NH2), methylamino group, ethylamino group, propylamino group, butylamino group, dimethylamino group, diethylamino group, anilino group, toluidino group, anisidino group, diphenylamino group, and N-methyl-N-phenylamino group.

[0371] Examples of monovalent groups containing a carbonyl group include formyl group, acyl group, carboxyl group, amide group, alkoxycarbonyl group, thiocarboxyl group, thioester group, etc., with monovalent groups containing a carbonyl group having 1 to 6 carbon atoms being preferred.

[0372] An acyl group is a substituent formed by linking a carbonyl group with an alkyl group, alkenyl group, or aryl group. The total number of carbon atoms derived from the carbonyl group (1) and the alkyl group, alkenyl group, or aryl group of the acyl group is preferably 2 to 20, more preferably 2 to 10, and even more preferably 2 to 6. Examples of acyl groups include acetyl group, propionyl group, butylcarbonyl group, vinylcarbonyl group, and benzoyl group.

[0373] The amide group includes an amide group (-CONH2) without substituents on the nitrogen atom, and an amide group in which some or all of the hydrogen atoms bonded to the nitrogen atom are substituted with carbon atoms. The total number of carbon atoms in the amide group is the sum of the carbon atoms derived from the carbonyl group (1) and the carbon atoms substituted on the nitrogen atom, which is preferably 1 to 20, more preferably 1 to 10, and even more preferably 1 to 5. Examples of amide groups include unsubstituted amide groups, N-methylamide groups, N-ethylamide groups, N-phenylamide groups, N,N-dimethylamide groups, and N-methyl-N-phenylamide groups.

[0374] An alkoxycarbonyl group is a substituent formed by linking a carbonyl group and an alkoxy group, and is also called an ester group. The total number of carbon atoms from the carbonyl group (1) and the alkoxy group is preferably 2 to 20, more preferably 2 to 10, and even more preferably 2 to 6. Examples of alkoxycarbonyl groups include methoxycarbonyl group, ethoxycarbonyl group, butoxycarbonyl group, and phenoxycarbonyl group.

[0375] A thioester group is a substituent formed by linking a carbonyl group with an alkylthio or arylthio group. The total number of carbon atoms derived from the carbonyl group (1) and the alkylthio or arylthio group is preferably 2 to 20, more preferably 2 to 10, and even more preferably 2 to 6. Examples of thioester groups include methylthiocarbonyl group, ethylthiocarbonyl group, butylthiocarbonyl group, and phenylthiocarbonyl group.

[0376] Furthermore, the monovalent group containing a carbonyl group may be a substituent in which one or more hydrogen atoms of an alkyl group are substituted with a carbonyl group. Examples of such substituents include 2-acetoxyethyl group, 2-acetoethyl group, and 2-(acetoacetoxy)ethyl group.

[0377] 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 even more preferably an alkylthio group having 1 to 5 carbon atoms. Examples of alkylthio groups include methylthio group, ethylthio group, propylthio group, isopropylthio group, and the like.

[0378] 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 even more preferably an arylthio group having 6 to 10 carbon atoms. Examples of arylthio groups include phenylthio groups and tolylthio groups.

[0379] Among the compounds that satisfy the above conditions, from the viewpoint of quality stability during storage of methacrylic acid-containing compositions, component A6 is selected from crotonic acid, 2-methylcrotonic 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-buten-2-one (isopropenylmethyl ketone), N-propylmethacrylamide, cinnamic acid, 3-methoxyacrylic acid, cis-crotonic acid, 2-ethylacrylic acid, 2-methylenepentanoic acid, and 4-methyl-2-pentenoic acid. Tenic acid, 2,4-pentadienoic acid, 2-methyl-2,4-pentadienoic acid, 2-hexenoic acid, 2-methyl-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-hexadienoic acid, ethyl methacrylate, isobutyl methacrylate, butyl methacrylate, methyl methacrylate Ropil, isoamyl methacrylate, cyclohexyl methacrylate, isobornyl methacrylate, hexyl methacrylate, propyl acrylate, butyl acrylate, methyl crotonate, cis-methyl crotonate, methyl 3,3-dimethylacrylate, methyl 2-ethylacrylate, methyl 2-methylene-3-butenoate, methyl 2-pentenoate, methyl 2,4-pentadienate, dimethyl fumarate, trans-3-hexen-2-one, methyl vinyl ketone, acrolein, crotonaldehyde, cis-crotonaldehyde, 2-methylene-3- Butanal, 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-octenal, 2,4-octadienal, 2,6-dimethyl-2-heptenal, 6-methyl-2-methyleneheptanal, 2,6-dimethyl-2,4-heptadienal, 6-methyl-2-methylene-3-heptenal, 2,5-dimethyl-2,4-hexadienedial, methacrylamide, hexadecanamide, 9-octadecenamide, or methacrylic anhydride are preferred, and crotonic acid, 2-methylcrotonic 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-buten-2-one (isopropenylmethyl ketone), N-propylmethacrylamide, cinnamic acid, or 3-methoxyacrylate Lylic acid is more preferred, crotonic acid, 2-methylcrotonic acid, 3,3-dimethylacrylic acid, 2-methylene-3-butenoic acid, 2-pentenoic acid, 2-methyl-2-pentenoic acid, methyl acrylate, 3-methyl-3-buten-2-one (isopropenylmethyl ketone), N-propylmethacrylamide, methacrylamide, and cinnamic acid are even more preferred, and crotonic acid, 2-methylcrotonic acid, 3,3-dimethylacrylic acid, 2-pentenoic acid, 2-methyl-2-pentenoic acid, methyl acrylate, isopropenylmethyl ketone, methacrylamide, and cinnamic acid are particularly preferred.

[0380] Component A6 may consist of one type or two or more types.

[0381] (Component B) The methacrylic acid-containing composition according to the sixth embodiment contains a polymerization inhibitor (component B). In this specification, a polymerization inhibitor means a compound that has the function of suppressing the polymerization reaction of methacrylic acid. Examples of polymerization inhibitors include phenolic compounds, quinone compounds, nitrobenzene compounds, N-oxyl compounds, amine compounds, phosphorus-containing compounds, sulfur-containing compounds, iron-containing compounds, copper-containing compounds, and manganese-containing compounds. By including component B, the polymerization reaction of methacrylic acid by the radical polymerization mechanism can be suppressed during storage of methacrylic acid. In addition, component B can trap the aforementioned hydroxyl radicals that are generated during 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 two different mechanisms: component A6 suppresses the generation of hydroxyl radicals, and component B removes the generated hydroxyl radicals. Therefore, it is considered that the decrease of component B can be efficiently suppressed.

[0382] Examples of polymerization inhibitors that are phenolic compounds include alkylphenols, hydroxyphenols, aminophenols, nitrophenols, nitrosophenols, alkoxyphenols, and tocopherols.

[0383] Examples of alkylphenols include o-cresol, m-cresol, p-cresol, 2-t-butyl-4-methylphenol, 2,4-dimethyl-6-t-butylphenol, 2,6-di-t-butyl-4-methylphenol, 2-t-butylphenol, 4-t-butylphenol, 2,4-di-t-butylphenol, 2-methyl-4-t-butylphenol, 4-t-butyl-2,6-dimethylphenol, 2,2'-methylenebis(6-t-butyl-4-methylphenol), 2,2'-methylenebis(4-ethyl-6-t-butylphenol), 4,4'-thiobis(3-methyl-6-t-butylphenol), and 3,5-di-t-butyl-4-hydroxytoluene.

[0384] Examples of hydroxyphenols include hydroquinone, 2-methylhydroquinone, 2-t-butylhydroquinone, 2,5-di-t-butylhydroquinone, 2,6-di-t-butylhydroquinone, 2,5-di-t-amylhydroquinone, 2-t-butylmethoxyhydroquinone, 2,3,5-trimethylhydroquinone, 2,5-dichlorohydroquinone, 1,2-dihydroxybenzene, 2-acetylhydroquinone, 4-methylcatechol, 4-t-butylcatechol, 2-methylresorcinol, 4-methylresorcinol, and 2,3-dihydroxyacetophenone.

[0385] Examples of aminophenols include o-aminophenol, m-aminophenol, p-aminophenol, 2-(N,N-dimethylamino)phenol, and 4-(ethylamino)phenol.

[0386] Examples of nitrophenols include o-nitrophenol, m-nitrophenol, p-nitrophenol, and 2,4-dinitrophenol. Examples of nitrosophenols include o-nitrosophenol, m-nitrosophenol, p-nitrosophenol, and α-nitroso-β-naphthol.

[0387] Examples of alkoxyphenols include 2-methoxyphenol, 2-ethoxyphenol, 2-isopropoxyphenol, 2-t-butoxyphenol, 4-methoxyphenol, 4-ethoxyphenol, 4-propoxyphenol, 4-butoxyphenol, 4-t-butoxyphenol, 4-heptoxyphenol, hydroquinone monobenzyl ether, t-butyl-4-methoxyphenol, di-t-butyl-4-methoxyphenol, pyrogallol-1,2-dimethyl ether, and hydroquinone monobenzoate.

[0388] Examples of tocopherols include α-tocopherol and 2,3-dihydro-2,2-dimethyl-7-hydroxybenzofuran.

[0389] Examples of polymerization inhibitors that are quinone compounds 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.

[0390] Examples of polymerization inhibitors that are nitrobenzene compounds include nitrobenzene, o-dinitrobenzene, m-dinitrobenzene, p-dinitrobenzene, 2,4-dinitrotoluene, dinitrojulene, and 2,2-diphenyl-1-picrylhydrazyl.

[0391] Examples of polymerization inhibitors that are N-oxyl compounds include 4-hydroxy-2,2,6,6-tetramethyl-piperidine-N-oxyl, 4-oxo-2,2,6,6-tetramethyl-piperidine-N-oxyl, 4-acetoxy-2,2,6,6-tetramethyl-piperidine-N-oxyl, 2,2,6,6-tetramethyl-piperidine-N-oxyl, piperidine-1-oxyl, 4-(dimethylamino)-2,2,6,6-tetramethyl-piperidine-N-oxyl, 4-amino-2,2,6,6-tetramethyl-piperidine-N-oxyl, 4-ethanoloxy-2,2,6,6-tetramethyl-piperidine-N-oxyl, and 4-benzoyloxy-2,2,6,6-tetramethylpiperidine-N-oxyl Examples include 2,2,5,5-tetramethyl-piperidine-N-oxyl, 3-amino-2,2,5,5-tetramethyl-piperidine-N-oxyl, 4,4',4''-tris(2,2,6,6-tetramethyl-piperidine-N-oxyl) phosphite, 3-oxo-2,2,5,5-tetramethylpyrrolidine-N-oxyl, pyrrolidine-1-oxyl, 2,2,5,5-tetramethyl-1-oxa-3-azacyclopentyl-3-oxy, 2,2,5,5-tetramethyl-3-pyrrolinyl-1-oxy-3-carboxylic acid, 2,2,3,3,5,5,6,6-octamethyl-1,4-diazacyclohexyl-1,4-dioxy, di-tert-butyl nitroxide, di-tert-amyl nitroxide, etc.

[0392] Examples of polymerization inhibitors that are amine compounds include N,N-diphenylamine, alkylated diphenylamine, 4,4'-dicumyl-diphenylamine, 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, and each group consists of 1 to 4 carbon atoms independently of each other, 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, Examples include N,N'-di-2-naphthyl-p-phenylenediamine, N,N-diethylhydroxylamine, 1,4-benzenediamine, N-(1,4-dimethylpentyl)-N'-phenyl-1,4-benzenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-1,4-benzenediamine, 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline, 2,2,4-trimethyl-1,2-dihydroquinoline polymer, aldol-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, and 1-hydroxy-4-benzoyloxy-2,2,6,6-tetramethylpiperidine.

[0393] Examples of polymerization inhibitors containing phosphorus include triphenylphosphine, triphenyl phosphite, triethyl phosphite, tris(isodecyl) phosphite, tris(tridecyl) phosphite, phenyldiisooctyl phosphite, phenyldiisodecyl phosphite, phenyldi(tridecyl) phosphite, diphenylisooctyl phosphite, diphenylisodecyl phosphite, diphenyltridecyl phosphite, phosphonic acid [1,1-diphenyl-4,4'-diylbistetrakis-2,4-bis(1,1-dimethylethyl)phenyl]ester, tris(nonylphenyl) phosphite, 4,4'-isopropylidenediphenolalkyl phosphite, tris(2,4-di-tert-butylphenyl) phosphite, tris(biphenyl) phosphite, and distearylpentaerythritol. Examples include di(2,4-di-tert-butylphenyl)pentaerythritol diphosphite, di(nonylphenyl)pentaerythritol diphosphite, phenylbisphenol A pentaerythritol diphosphite, tetra(tridecyl)-4,4'-butylidenebis(3-methyl-6-tert-butylphenol) diphosphite, hexa(tridecyl)-1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane triphosphite, 3,5-di-tert-butyl-4-hydroxybenzyl phosphate diethyl ester, sodium-bis(4-tert-butylphenyl) phosphate, sodium-2,2'-methylene-bis(4,6-di-tert-butylphenyl) phosphate, and 1,3-bis(diphenoxyphosphonyloxy)benzene.

[0394] Examples of polymerization inhibitors containing sulfur include diphenyl sulfide, phenothiazine, 3-oxofhenothiazine, 5-oxofhenothiazine, phenothiazine dimers, 1,4-dimercaptobenzene, 1,2-dimercaptobenzene, 2-mercaptophenol, 4-mercaptophenol, 2-(methylthio)phenol, 3,7-bis(dimethylamino)phenothiazinium chloride, and elemental sulfur.

[0395] Examples of polymerization inhibitors that contain iron include iron(III) chloride.

[0396] Examples of polymerization inhibitors containing copper include copper dimethyldithiocarbamate, copper diethyldithiocarbamate, copper dibutyldithiocarbamate, copper salicylate, copper acetate, copper thiocyanate, copper nitrate, copper chloride, copper carbonate, copper hydroxide, copper acrylate, and copper methacrylate.

[0397] Examples of manganese-containing polymerization inhibitors include manganese dialkyldithiocarbamate (the alkyl group is one of methyl, ethyl, propyl, or butyl groups, and may be the same or different), manganese diphenyldithiocarbamate, manganese formate, manganese acetate, manganese octanoate, manganese naphthenate, manganese permanganate, and manganese salts of ethylenediaminetetraacetic acid.

[0398] Among the above, from the viewpoint of quality stability during storage of the methacrylic acid-containing composition, component B is preferably at least one polymerization inhibitor selected from the group consisting of phenolic compounds, N-oxyl compounds, amine compounds, phosphorus-containing compounds, and sulfur-containing compounds. For example, it is preferably at least one polymerization inhibitor selected from the group consisting of hydroquinone, 4-methoxyphenol, 2,4-dimethyl-6-t-butylphenol, 2,6-di-t-butyl-4-methylphenol, 4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl, N,N-diphenylamine, N-nitrosodiphenylamine, triphenyl phosphite, and phenothiazine. Component B is more preferably a phenolic compound, for example at least one polymerization inhibitor selected from the group consisting of hydroquinone, 4-methoxyphenol, 2,4-dimethyl-6-t-butylphenol, and 2,6-di-t-butyl-4-methylphenol. Component B is more preferably at least one polymerization inhibitor selected from the group consisting of, for example, hydroquinone, 4-methoxyphenol, and 2,6-di-t-butyl-4-methylphenol. Component B is particularly preferably at least one polymerization inhibitor selected from the group consisting of, for example, hydroquinone and 4-methoxyphenol.

[0399] Component B may be one type or two or more types. If a methacrylic acid-containing composition contains a compound that corresponds to both component A6 and component B, that compound shall be considered as component B. In other words, the methacrylic acid-containing composition must contain a component A6 other than that compound. If two or more compounds that correspond to both component A6 and component B are contained, the compound with the highest molar concentration in the methacrylic acid-containing composition shall be considered as component B, and the other compounds shall be considered as component A6.

[0400] (Concentrations of component A6 and component B) The concentration of component A6 is M A6 (μmol / L), the concentration of component B is M BWhen expressed as (μmol / L), from the viewpoint of efficiency in suppressing the consumption of polymerization inhibitors, M B / M A6 It is preferably 0.0005 to 500, more preferably 0.001 to 450, even more preferably 0.005 to 400, and even more preferably 0.005 to 350.

[0401] M A6 The concentration is preferably 1 to 85,000 μmol / L. A6 When the concentration is 1 μmol / L or higher, the effect of suppressing the decomposition of polymerization inhibitors can be sufficiently obtained. A6 By having a concentration of 85,000 μmol / L or less, the amount of impurities produced when a methacrylic acid polymer is manufactured by polymerization of the methacrylic acid-containing composition according to the sixth embodiment can be reduced, thereby preventing adverse effects on the physical properties of the polymer. A6 The lower limit is more preferably 10 μmol / L or more, even more preferably 30 μmol / L or more, even more preferably 50 μmol / L or more, particularly preferably 70 μmol / L or more, especially preferably 80 μmol / L or more, and most preferably 85 μmol / L or more. A6 The upper limit is more preferably 65,000 μmol / L or less, even more preferably 45,000 μmol / L or less, particularly preferably 25,000 μmol / L or less, especially preferably 15,000 μmol / L or less, and most preferably 5,000 μmol / L or less.

[0402] M B The concentration is preferably 1 to 50,000 μmol / L. B When the concentration is 1 μmol / L or higher, the effect of suppressing the decomposition of polymerization inhibitors can be sufficiently obtained. B By having a concentration of 50,000 μmol / L or less, the amount of impurities produced when a methacrylic acid polymer is manufactured by polymerization of the methacrylic acid-containing composition according to the sixth embodiment can be reduced, thereby preventing adverse effects on the physical properties of the polymer. BThe lower limit is more preferably 10 μmol / L or higher, even more preferably 100 μmol / L or higher, particularly preferably 1000 μmol / L or higher, and especially preferably 2000 μmol / L or higher. B The upper limit is more preferably 40,000 μmol / L or less, even more preferably 30,000 μmol / L or less, and particularly preferably 25,000 μmol / L or less.

[0403] (Concentration of methacrylic acid) The concentration of methacrylic acid in the methacrylic acid-containing composition according to the sixth embodiment is 98.00 to 99.99% by mass. By having a methacrylic acid concentration of 98.00% by mass or higher, the amount of impurities produced when a methacrylic acid polymer is manufactured by polymerization of the methacrylic acid-containing composition can be reduced, and adverse effects on the physical properties of the polymer can be prevented. Furthermore, by having a methacrylic acid concentration of 99.99% by mass or lower, purification costs can be reduced. The lower limit of the methacrylic acid concentration is more preferably 98.50% or higher, even more preferably 99.00% or higher, particularly preferably 99.50% or higher, and most preferably 99.80% by mass or higher.

[0404] (Component C) The methacrylic acid-containing composition according to the sixth embodiment may further contain component C, which is another compound, as long as the concentration of methacrylic acid satisfies 98.00 to 99.99% by mass. Component C may include impurities generated during the production of methacrylic acid. For example, methacrylic acid may contain diacetyl as an impurity, but 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, even more preferably 10 μmol / L or less, and particularly preferably 1 μmol / L or less.

[0405] (Analysis of methacrylic acid-containing compositions) The presence of component A6, component B, component C, and water in a methacrylic acid-containing composition can be confirmed, for example, by GC-MS measurement. If the GC-MS chart of the methacrylic acid-containing composition shows a peak at the same retention time as the standard of component A6, and the m / z value detected in the mass spectrum of that peak matches the exact mass of component A6, then the methacrylic acid-containing composition can be determined to contain component A6. If a standard of component A6 is not available, the peak can be determined to be the component A6 peak if the mass spectrum pattern of the peak appearing in the GC-MS chart of the methacrylic acid-containing composition matches the mass spectrum pattern of component A6 recorded in a mass spectrum database. In other words, the methacrylic acid-containing composition can be determined to contain component A6. Examples of mass spectrum databases include NIST20, NIST17, NIST14, and NIST14s. Furthermore, if the volatility is low and detection by GC-MS measurement is not possible, detection can be performed using LC-MS. The presence of component B, component C, and water can also be confirmed by a similar method. Furthermore, the concentration of methacrylic acid can be calculated, for example, by performing a GC-FID measurement of the methacrylic acid-containing composition, quantifying it using the area percentage method, and correcting it using the moisture concentration quantified with a Karl Fischer moisture meter. The concentration of component A6 can be calculated, for example, by performing a GC measurement of the methacrylic acid-containing composition and quantifying it using the internal standard method. If a standard sample of component A6 cannot be obtained and quantification cannot be performed by the internal standard method, the concentration of component A6 can be calculated using the following formula by performing a GC-FID measurement of any organic compound with a known concentration under the same conditions as the methacrylic acid-containing composition.

[0406]

number

[0407] 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 A6is the peak area of ​​component A6, S is the peak area of ​​the organic compound with a known concentration, and M is the concentration (μmol / L) of the organic compound with a known concentration.

[0408] If the volatility is low and quantification by GC measurement is not possible, quantification can be performed using chromatographic methods such as LC. The concentrations of components B and C can also be calculated using the same method as for component A6 described above. Furthermore, the presence of water in the methacrylic acid-containing composition, and its concentration, can be confirmed by the Karl Fischer method.

[0409] [Methacrylic acid-containing composition production method] A method for producing a methacrylic acid-containing composition according to the sixth embodiment is to add component A6 and component B to methacrylic acid. The methacrylic acid may be a commercially available product, or methacrylic acid produced by known methods such as the acetone cyanohydrin (ACH) method or the C4 direct oxidation method may be used. Component A6 and component B may be commercially available products, or synthesized by known methods may be used. When using methacrylic acid produced by known methods such as the acetone cyanohydrin (ACH) method or the C4 direct oxidation method, component A6 or component B may be added as a raw material or during the manufacturing process to produce the methacrylic acid-containing composition. Furthermore, if component A6 or component B is produced as a by-product in the methacrylic acid manufacturing process, the methacrylic acid-containing composition may be produced by leaving a portion of the produced component A6 or component B.

[0410] [Methods for evaluating storage stability and thermal stability] The methacrylic acid-containing composition according to the sixth embodiment exhibits high quality stability during storage. Methods for evaluating the quality stability of the methacrylic acid-containing composition during storage include, for example, actually storing the methacrylic acid-containing composition for a long period and confirming the decrease in polymerization inhibitor. Alternatively, from the viewpoint of ease of operation, a method of heating the methacrylic acid-containing composition for a short time and confirming the decrease in polymerization inhibitor may 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 this invention, the quality stability of the methacrylic acid-containing composition during storage was evaluated by the decrease in polymerization inhibitor when the methacrylic acid-containing composition was stored at 25°C for 21 days.

[0411] [Methacrylic acid ester production method] The method for producing methacrylic acid ester according to the sixth embodiment includes a step of esterifying the methacrylic acid-containing composition according to the sixth embodiment. The alcohol reacted with the methacrylic acid-containing composition is not particularly limited and includes, for example, methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, etc. The resulting methacrylic acid esters include, for example, methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, butyl methacrylate, isobutyl methacrylate, etc. The esterification reaction can be carried out in the presence of an acidic catalyst such as a sulfonic acid type cation exchange resin. The temperature during the esterification reaction is preferably 50 to 200°C. The pressure during the esterification reaction, the position of the catalyst in the reactor, and the proportion of the catalyst in the reactor are not particularly limited, and commonly used configurations can be applied.

[0412] [Methacrylic acid polymer production method according to the sixth embodiment] A method for producing a methacrylic acid polymer according to the sixth embodiment includes a step of polymerizing a polymerizable composition containing the methacrylic acid-containing composition according to the sixth embodiment.

[0413] The polymerizable composition may optionally contain monomers copolymerizable with methacrylic acid and other additives.

[0414] Examples of monomers copolymerizable with methacrylic acid include the following: Methacrylic acid esters such as methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, iso-butyl methacrylate, tert-butyl methacrylate, 2-ethylhexyl methacrylate, phenyl methacrylate, or benzyl methacrylate; Acrylic acid esters such as methyl acrylate, ethyl acrylate, n-butyl acrylate, iso-butyl acrylate, tert-butyl acrylate, or 2-ethylhexyl acrylate; Unsaturated carboxylic acids such as acrylic acid, maleic acid, or itaconic acid; Unsaturated carboxylic acid anhydrides such as maleic anhydride or itaconic anhydride; Maleimides such as N-phenylmaleimide or N-cyclohexylmaleimide; 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, or 2-hydroxypropyl methacrylate, or other hydroxyl group-containing vinyl monomers; Vinyl esters such as vinyl acetate or vinyl benzoate; Vinyl chloride, vinylidene chloride, and their derivatives; Nitrogen-containing vinyl monomers such as methacrylamide or acrylonitrile; Epoxy group-containing monomers such as glycidyl acrylate or glycidyl methacrylate; Aromatic vinyl monomers such as styrene or α-methylstyrene; Alkane diol 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; 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; Vinyl monomers having two or more ethylenically unsaturated bonds in their molecules, such as divinylbenzene; Unsaturated polyester prepolymer obtained from at least one polycarboxylic acid containing an ethylenically unsaturated polycarboxylic acid and at least one diol; A vinyl ester prepolymer obtained by modifying the terminals of epoxy groups with acrylic.

[0415] Among the above, the monomer copolymerizable with methacrylic acid is preferably at least one selected from the group consisting of methacrylic acid esters and acrylic acid esters. The monomer copolymerizable with methacrylic acid is more preferably a methacrylic acid ester, and particularly preferably methyl methacrylate.

[0416] The monomer copolymerizable with methacrylic acid may be one type or two or more types. Furthermore, if component A6 is a monomer copolymerizable with methacrylic acid, component A6 may be used as the monomer copolymerizable with methacrylic acid, or a monomer copolymerizable with methacrylic acid may be used separately from component A6.

[0417] In a polymerizable composition, the upper limit of the content of monomers copolymerizable with methacrylic acid is preferably 99.99 parts by mass or less per 100 parts by mass of the polymerizable composition. The lower limit of the content of monomers copolymerizable with methacrylic acid is preferably 50 parts by mass or more, more preferably 60 parts by mass or more, even more preferably 70 parts by mass or more, particularly preferably 80 parts by mass or more, and most preferably 90 parts by mass or more per 100 parts by mass of the polymerizable composition. The upper limit of the content of monomers copolymerizable with methacrylic acid is more preferably 99.9 parts by mass or less per 100 parts by mass of the polymerizable composition, and even more preferably 99 parts by mass or less.

[0418] Other additives include polymerization initiators. The polymerizable composition may also contain, as needed, chain transfer agents, mold release agents, lubricants, plasticizers, antioxidants, antistatic agents, light stabilizers, UV absorbers, flame retardants, flame retardant aids, polymerization inhibitors, fillers, pigments, dyes, silane coupling agents, leveling agents, defoamers, fluorescent agents, etc. The other additives may be one type or two or more types.

[0419] Examples of polymerization initiators include the following: 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(cyclohexanecarbonitride), and dimethyl-2,2'-azobisisobutyrate; Benzoyl peroxide, 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane, 1,1-bis(t-butylperoxy)cyclohexane, 1,1-bis(t-butylperoxy)-3,5,5-trimethylcyclohexane, t-butylperoxy-2-ethylhexanoate, t-butylperoxyisobutyrate, t-butylperoxybenzoate, t-hexylperoxybenzoate, t-butylperoxyisopropyl monocarbonate, t-butylperoxy-3,5,5-trimethylhexanoate, t-butylperoxylaurate, t-butylperoxyacetate, t-hexylperoxyisopropyl monocarbonate, t-hexyl peroxy Organic peroxides such as -oxy-2-ethylhexanoate, t-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 peroxyisononate, 1,1,2-trimethylpropyl peroxyisononate, di-t-butyl peroxide, di-t-hexyl peroxide, lauroyl peroxide, and dilauroyl peroxide; Persulfate compounds such as potassium persulfate; A redox polymerization initiator.

[0420] Among the above, from the viewpoint of storage stability and reactivity with methacrylic acid and copolymerizable monomers, the polymerization initiator is preferably at least one selected from the group consisting of azo compounds and organic peroxides. The amount of polymerization initiator used is preferably 0.0001 to 1 part by mass per 100 parts by mass of methacrylic acid and monomers copolymerizable with methacrylic acid.

[0421] Polymerization methods for polymerizable compositions include, for example, bulk polymerization, solution polymerization, emulsion polymerization, and suspension polymerization. The polymerization temperature is preferably 125 to 210°C. This allows for obtaining an appropriate polymerization rate. The lower limit of the polymerization temperature is more preferably 130°C or higher, and the upper limit is more preferably 180°C or lower. The polymerization time is not particularly limited and can be, for example, 0.5 to 24 hours. [Examples]

[0422] The embodiments will be described in more detail below in the Examples and Comparative Examples, but the present invention is not limited to these embodiments. Unless otherwise specified, "%" and "ppm" in the Examples and Comparative Examples mean "weight percent" and "weight ppm" respectively. The water concentration in the methacrylic acid reagent was calculated using the Karl Fischer method. The composition of the methacrylic acid-containing composition before storage was calculated from the amount of each raw material added. The amount of polymerization inhibitor after storage was quantified using the absolute calibration curve method with GC-FID. The measurement conditions for GC-FID are shown below. Equipment: GC-FID (product name: GC7890B, manufactured by Agilent)

[0423] [GC conditions] Column (Product name: Rtx-1701, manufactured by Restek) Length: 30m, Inner diameter: 0.25mm, Film thickness: 1.00μm Injection volume: 1.0μL Evaporation chamber temperature: 260℃ Column oven temperature: Hold at 40°C for 10 minutes, then increase the temperature from 40°C to 2400°C at a rate of 10°C / minute, and hold at 240°C for 10 minutes. Carrier gas: Helium Injection mode: Split (Split ratio 50) Control mode: Constant linear velocity (39.723 cm / sec) Detector temperature: 260℃ Detector H2 flow rate: 30 mL / min Detector air flow rate: 400 mL / min Makeup helium flow rate: 25 mL / min

[0424] The moisture concentration was quantified using the Karl Fischer method with an automated moisture analyzer (product name: AQV-2200, manufactured by Hiranuma Sangyo Co., Ltd.).

[0425] (Example a1) Reagent 2-isopropylhydroquinone was used as component A1, and 0.0192 g of component A1 was added to 10.0081 g of reagent methacrylic acid (containing a water concentration of 366 ppm and a 4-methoxyphenol concentration of 306 ppm as component B1) to prepare a methacrylic acid solution (Solution A-a1). The concentration of component A1 in Solution A-a1 is shown in Table 1. Next, 0.0526 g of solution A-a1 was added to 9.9585 g of reagent methacrylic acid (water concentration 366 ppm, 4-methoxyphenol concentration as component B1 306 ppm) to prepare a methacrylic acid-containing composition. The concentrations of each component in the methacrylic acid-containing composition are shown in Table 2. The obtained methacrylic acid-containing composition was stored at 25°C for 21 days. Table 2 shows the rate of decrease of the polymerization inhibitor (component B1) in the methacrylic acid-containing composition after storage.

[0426] (Examples a2, a3, a5) Solution Aa 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. Next, MAA-containing compositions were prepared in the same manner as in Example a1, except that the amounts of reagent MAA and Aa solution were changed as shown in Table 2. The rate of decrease of polymerization inhibitor (component B1) in the methacrylic acid-containing compositions after storage is shown in Table 2.

[0427] (Example a4) Solution A-a4 was prepared in the same manner as in Example a1, except that reagent 2-phenylisobutyric acid was used for component A. Next, using hydroquinone as component B2, 0.4323 g of component B2 was added to 40.0050 g of reagent methacrylic acid (water concentration 366 ppm, 4-methoxyphenol concentration as component B1 306 ppm) to prepare methacrylic acid solution (B-a4). The concentration of component B2 in the B-a4 solution is shown in Table 1. Next, 0.0600 g of solution A-a4 and 0.2507 g of solution B-a4 were added to 9.7103 g of reagent methacrylic acid (water concentration 366 ppm, 4-methoxyphenol concentration as component B1 306 ppm) to prepare a methacrylic acid-containing composition. The concentrations of each component in the methacrylic acid-containing composition are shown in Table 2. The rate of decrease of the polymerization inhibitor (component B1) in the methacrylic acid-containing composition after storage is also shown in Table 2.

[0428] (Example a6) Using reagent-grade 2-phenylisobutyric acid as component A1, a methacrylic acid-containing composition was prepared by adding 0.0089 g of reagent-grade methacrylic acid (water concentration 366 ppm, 4-methoxyphenol concentration as component B1 306 ppm) to 9.9955 g of reagent-grade methacrylic acid. The concentrations of each component in the methacrylic acid-containing composition are shown in Table 2.

[0429] (Examples a7, a8) Solution Aa 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. Solution Bb 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 reagent MAA and component B were changed as shown in Table 1. Next, MAA-containing compositions were prepared in the same manner as in Example a4, except that the amounts of reagent MAA, solution Aa, and solution Bb were changed as shown in Table 2. The rate of decrease of polymerization inhibitor (component B1) in the methacrylic acid-containing compositions after storage is shown in Table 2.

[0430] (Comparative Example a1) Using reagent 4-methoxyphenol as component B1, ratio A-b1 was prepared by adding 0.4016 g of 4-methoxyphenol to 40.0219 g of reagent methacrylic acid (water concentration 366 ppm, 4-methoxyphenol concentration as component B1 306 ppm). Next, 0.5000 g of solution B-a1 was added to 19.5000 g of reagent methacrylic acid (water concentration 366 ppm) to prepare a methacrylic acid-containing composition. The concentrations of each component in the methacrylic acid-containing composition are shown in Table 2. The obtained methacrylic acid-containing composition was stored in the same manner as in Example a1. Table 2 shows the rate of decrease of the polymerization inhibitor (component B1) in the methacrylic acid-containing composition after storage.

[0431] (Comparative example a2) The reagent methacrylic acid (water concentration 366 ppm, 4-methoxyphenol concentration as component B1 306 ppm) was stored at 25°C for 21 days. Table 2 shows the rate of decrease of the polymerization inhibitor (component B1) in the methacrylic acid-containing composition after storage.

[0432] (Comparative example a3) Solution Aa was prepared in the same manner as in Example a1, except that the compound shown in Table 1 was used as component A, and the amounts of reagent MAA and component A were changed as shown in Table 1. A methacrylic acid-containing composition was prepared by adding 0.0971 g of solution Aa and 0.0565 g of pure water to 19.4088 g of reagent methacrylic acid (water concentration 366 ppm, 4-methoxyphenol concentration 306 ppm). The concentrations of each component in the methacrylic acid-containing composition are shown in Table 2. The rate of decrease of the polymerization inhibitor (component B1) in the methacrylic acid-containing composition after storage is also shown in Table 2.

[0433] [Table 1]

[0434] [Table 2]

[0435] As shown in Tables 1 and 2, in Examples a1 to a8, the rate of decrease in polymerization inhibitor (component B1) in the methacrylic acid composition after storage was suppressed. This indicates high quality stability during storage.

[0436] (Examples b1-b9) The Ca 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 reagent MAA and component A21 were changed as shown in Table 3. Next, an MAA-containing composition was prepared in the same manner as in Example a1, except that the amounts of reagent MAA and Ca solution were changed as shown in Table 4. The concentrations of each component in the methacrylic acid-containing composition are shown in Table 4. The rate of decrease of the polymerization inhibitor (component B1) in the methacrylic acid-containing composition after being stored at 25°C for 21 days is shown in Table 4.

[0437] (Comparative Example b1) A methacrylic acid-containing composition was prepared by adding 0.4611 g of reagent 2,3,5,6-tetramethylpyrazine as component A21 to 19.5520 g of reagent methacrylic acid (water concentration 366 ppm, 4-methoxyphenol concentration as component B1 306 ppm). The concentrations of each component in the methacrylic acid-containing composition are shown in Table 4. The rate of decrease of the polymerization inhibitor (component B1) in the methacrylic acid-containing composition after storage at 25°C for 21 days is shown in Table 4.

[0438] [Table 3]

[0439] [Table 4]

[0440] 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. This indicates high quality stability during storage.

[0441] (Examples c1, c2, c3, c5) Ca 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 reagent MAA and component A3 were changed as shown in Table 5. Next, MAA-containing compositions were prepared in the same manner as in Example a1, except that the amounts of reagent MAA and Ca solution were changed as shown in Table 6. The concentrations of each component in the methacrylic acid-containing compositions are shown in Table 6. The rate of decrease of the polymerization inhibitor (component B1) in the methacrylic acid-containing compositions stored at 25°C for 21 days is shown in Table 6.

[0442] (Example c4) A MAA-containing composition was prepared in the same manner as in Example a4, except that reagent t-butylphenyl ether was used for component A3. The concentrations of each component in the methacrylic acid-containing composition are shown in Table 6. The rate of decrease 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.

[0443] (Example c6) A MAA-containing composition was prepared in the same manner as in Example a6, except that reagent t-butylphenyl ether was used for component A3. The concentrations of each component in the methacrylic acid-containing composition are shown in Table 6. The rate of decrease 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.

[0444] (Examples c7, c8) The Ca solution was prepared in the same manner as in Example a1, except that t-butylphenyl ether was used as component A3. Then, the Cb solutions were prepared in the same manner as in Example a7. The amounts of reagent MAA, Ca solution, and Cb solution were added as shown in Table 6 to prepare methacrylic acid-containing compositions. The concentrations of each component in the methacrylic acid-containing compositions are shown in Table 6. The rate of decrease of the polymerization inhibitor (component B1) in the methacrylic acid-containing compositions stored at 25°C for 21 days is shown in Table 6.

[0445] (Comparative Example c1) A methacrylic acid-containing composition was prepared in the same manner as in Comparative Example b1, except that t-butylphenyl ether was used for component A. The concentrations of each component in the methacrylic acid-containing composition are shown in Table 6. The rate of decrease 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.

[0446] (Comparative Example c2) A methacrylic acid-containing composition was prepared in the same manner as in Comparative Example a3, except that t-butylphenyl ether was used as component A3. The concentrations of each component in the methacrylic acid-containing composition are shown in Table 6. The rate of decrease 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.

[0447] [Table 5]

[0448] [Table 6]

[0449] 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. This indicates high quality stability during storage.

[0450] (Examples d1-d6) Da 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 reagent MAA and component A4 were changed as shown in Table 7. Next, MAA-containing compositions were prepared in the same manner as in Example a1, except that the amounts of reagent MAA and Da solution were changed as shown in Table 8. The concentrations of each component in the methacrylic acid-containing compositions are shown in Table 8. The rate of decrease of the polymerization inhibitor (component B1) in the methacrylic acid-containing compositions stored at 25°C for 21 days is shown in Table 8.

[0451] (Example d7) 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 each component in the methacrylic acid-containing composition are shown in Table 8. The rate of decrease 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.

[0452] (Example d8) Solution Da 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 reagent MAA and component A4 were changed as shown in Table 7. Next, an MAA-containing composition was prepared in the same manner as in Example a1, except that the amounts of reagent MAA and Da solution were changed as shown in the table. The concentrations of each component in the methacrylic acid-containing composition are shown in Table 8. The rate of decrease 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.

[0453] (Example d9) 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 each component in the methacrylic acid-containing composition are shown in Table 8. The rate of decrease 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.

[0454] (Examples d10, d11) The Da solution was prepared in the same manner as in Example a1, except that methacrylonitrile was used as component A4. Then, the Db solution was prepared in the same manner as in Example a7. A methacrylic acid-containing composition was prepared by adding reagent MAA, solution Da, and solution Db in the amounts shown in Table 8. The concentrations of each component in the methacrylic acid-containing composition are shown in Table 8. The rate of decrease 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.

[0455] (Comparative Example d1) A methacrylic acid-containing composition was prepared in the same manner as in Comparative Example b1, except that methacrylonitrile was used for component B. The concentrations of each component in the methacrylic acid-containing composition are shown in Table 8. The obtained methacrylic acid-containing composition was stored in the same manner as in Example d1. Table 8 shows the rate of decrease in polymerization inhibitor (component B1) in the methacrylic acid-containing composition after storage.

[0456] (Comparative example d2) A methacrylic acid-containing composition was prepared in the same manner as in Comparative Example a1, except that methacrylonitrile was used for component B. The concentrations of each component in the methacrylic acid-containing composition are shown in Table 8. The rate of decrease 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.

[0457] [Table 7]

[0458] [Table 8]

[0459] As shown in Tables 7 and 8, in Examples d1 to d11, the decomposition of the polymerization inhibitor (component B1) was suppressed in the methacrylic acid composition after storage. This indicates high quality stability during storage.

[0460] (Examples e1-e9) Solution Ea was prepared in the same manner as in Example a1, except that the compound shown in Table 9 was used as component A5, and the amounts of reagent MAA and component A5 were changed as shown in Table 9. Next, an MAA-containing composition was prepared in the same manner as in Example a1, except that the amounts of reagent MAA and solution Ea were changed as shown in the table. The concentrations of each component in the methacrylic acid-containing composition are shown in Table 10. The rate of decrease 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.

[0461] (Example e10) A methacrylic acid-containing composition was prepared in the same manner as in Example a4, except that isobutyric acid was used for component A5. The concentrations of each component in the methacrylic acid-containing composition are shown in Table 10. The rate of decrease 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.

[0462] (Example e11) A methacrylic acid-containing composition was prepared in the same manner as in Example a6, except that isobutyric acid was used for component A5. The concentrations of each component in the methacrylic acid-containing composition are shown in Table 10. The rate of decrease 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.

[0463] (Example e12) A methacrylic acid-containing composition was prepared in the same manner as in Example a7, except that isobutyric acid was used for component A5. The concentrations of each component in the methacrylic acid-containing composition are shown in Table 10. The rate of decrease 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.

[0464] (Comparative Example e1) A methacrylic acid-containing composition was prepared in the same manner as in Comparative Example b1, except that isobutyric acid was used as component A5. The concentrations of each component in the methacrylic acid-containing composition are shown in Table 10. The rate of decrease 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.

[0465] [Table 9]

[0466] [Table 10]

[0467] 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. This indicates high quality stability during storage.

[0468] (Examples f1–f10) Each Fa solution was prepared in the same manner as in Example a1, except that the compounds shown in Table 11 were used as component A6, and the amounts of reagent MAA and component A6 were changed as shown in Table 11. Next, MAA-containing compositions were prepared in the same manner as in Example a1, except that the amounts of reagent MAA and Fa solution were changed as shown in the table. The concentrations of each component in the methacrylic acid-containing compositions are shown in Table 12. The rate of decrease of the polymerization inhibitor (component B1) in the methacrylic acid-containing compositions stored at 25°C for 21 days is shown in Table 12.

[0469] [Table 11]

[0470] [Table 12]

[0471] 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. This indicates high quality stability during storage.

[0472] A methacrylic acid ester can be obtained by esterifying the methacrylic acid-containing composition obtained in this embodiment. Furthermore, a methacrylic acid polymer can be obtained by polymerizing a polymerizable composition containing the methacrylic acid-containing composition obtained in this embodiment. [Industrial applicability]

[0473] According to the present invention, it is possible to provide a methacrylic acid-containing composition with high quality stability in which the decomposition of polymerization inhibitors during storage is suppressed. According to the present invention, a methacrylic acid-containing composition that can be used as a raw material for acrylic resins, etc., can be stored stably for a long period of time, making it industrially useful.

Claims

1. Methacrylic acid and, Component A1 is a compound represented by the following formula (11), Component A5 is a compound represented by the following formula (51), Component B, which is a polymerization inhibitor, It contains, The aforementioned component B contains at least one selected from the group consisting of hydroquinone, 4-methoxyphenol, 2,4-dimethyl-6-t-butylphenol, and 2,6-di-t-butyl-4-methylphenol. The concentration of methacrylic acid is 98.00 to 99.99% by mass. A methacrylic acid-containing composition wherein the concentration M of component A5 is 1 to 50,000 μmol / L. 【Chemistry 1】 In formula (11), R １ａ , R ２ａ , R ３ａ , R 4a and R ６ａ Each of these is independently a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an s-butyl group, an i-butyl group, a t-butyl group, a hydroxyl group, or a methoxy group. R 5a is a hydroxyl group, R ７ａ This is a hydrogen atom, a carboxyl group, or a methoxycarbonyl group. 【Chemistry 2】 In formula (51), R １ｅ and R ２ｅ Each of these is independently a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, or an isopropyl group. R ３ｅ It is a hydroxyl group. However, R １ｅ and R ２ｅ have a total number of carbon atoms of 2 or more.

2. The concentration of component A1 is M Ａ１ (μmol / L), the concentration of component B is M Ｂ When expressed as (μmol / L), M Ｂ / M Ａ１ The methacrylic acid-containing composition according to claim 1, wherein the ratio is 0.005 to 100.

3. The concentration of component A1 is M Ａ１ When expressed as (μmol / L), M Ａ１ The methacrylic acid-containing composition according to claim 1, wherein the concentration is 1 to 50,000 μmol / L.

4. Said M Ａ１ The methacrylic acid-containing composition according to claim 3, wherein the concentration is 10 to 30,000 μmol / L.

5. The methacrylic acid-containing composition according to Claim 1, further comprising at least one selected from the group consisting of component A21, which is a compound represented by the following formula (21); component A3, which is a compound represented by the following formula (31); component A4, which is a compound represented by the following formula (41); and component A6, which is a compound represented by the following formula (61). 【Transformation 3】 In formula (21), R1b, R2b, R3b, and R4b are each independently a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, or a methoxy group. 【Chemistry 4】 In formula (31), R1c, R2c, R3c, R4c, R5c, R6c, and R7c are each independently a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an s-butyl group, an i-butyl group, a t-butyl group, a hydroxyl group, a methoxy group, a carboxyl group, or a methoxycarbonyl group. 【Transformation 5】 In formula (41), R d is a methyl group, an ethyl group, a vinyl group, an isopropenyl group, or a phenyl group, and these groups may have further substituents. 【Transformation 6】 In formula (61), R1f, R2f, and R3f are each independently a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, or an isopropyl group. R 4f is a hydroxyl group. However, this excludes the case where R1f = H, R2f = H, R3f = CH3, and R4f = OH, i.e., when component A6 is methacrylic acid. H represents a hydrogen atom, C represents a carbon atom, and O represents an oxygen atom. The sum of the number of carbon atoms in R1f, R2f, and R3f is 1 or more.

6. The concentration of component A21 is M Ａ２１ (μmol / L), the concentration of component B is M Ｂ When expressed as (μmol / L), M Ｂ / M Ａ２１ The methacrylic acid-containing composition according to claim 5, wherein the ratio is 0.005 to 100.

7. The concentration of component A21 is M Ａ２１ When expressed as (μmol / L), M Ａ２１ The methacrylic acid-containing composition according to claim 5, wherein the concentration is 1 to 50,000 μmol / L.

8. Said M Ａ２１ The methacrylic acid-containing composition according to claim 7, wherein the concentration is 10 to 30,000 μmol / L.

9. The concentration of component A3 is M Ａ３ When expressed as (μmol / L), M Ａ３ The methacrylic acid-containing composition according to claim 5, wherein the concentration is 1 to 50,000 μmol / L.

10. Said M Ａ３ The methacrylic acid-containing composition according to claim 9, wherein the concentration is 10 to 30,000 μmol / L.

11. The concentration of component A3 is M Ａ３ (μmol / L), and the concentration of component B is M Ｂ When expressed as (μmol / L), M Ｂ / M Ａ３ The methacrylic acid-containing composition according to claim 5, wherein the ratio is 0.005 to 100.

12. The concentration of component A4 is M Ａ４ (μmol / L), the concentration of component B is M Ｂ When expressed as (μmol / L), M Ｂ / M Ａ４ The methacrylic acid-containing composition according to claim 5, wherein the ratio is 0.005 to 100.

13. The concentration of component A4 is M Ａ４ When expressed as (μmol / L), M Ａ４ The methacrylic acid-containing composition according to claim 5, wherein the concentration is 1 to 20,000 μmol / L.

14. Said M Ａ４ The methacrylic acid-containing composition according to claim 13, wherein the concentration is 10 to 15,000 μmol / L.

15. The concentration of component B is M Ｂ When expressed as (μmol / L), M Ｂ / M Ａ５ The methacrylic acid-containing composition according to claim 1, wherein the ratio is 0.005 to 100.

16. Said M Ａ５ The methacrylic acid-containing composition according to claim 1, wherein the concentration is 10 to 30,000 μmol / L.

17. The concentration of component A6 is M Ａ６ (μmol / L), the concentration of component B is M Ｂ When expressed as (μmol / L), M Ｂ / M Ａ６ The methacrylic acid-containing composition according to claim 5, wherein the ratio is 0.005 to 100.

18. The concentration of component A6 is M Ａ６ When expressed as (μmol / L), M Ａ６ The methacrylic acid-containing composition according to claim 5, wherein the concentration is 1 to 85,000 μmol / L.

19. Said M Ａ６ The methacrylic acid-containing composition according to claim 18, wherein the concentration is 10 to 40,000 μmol / L.

20. The concentration of component B is M Ｂ When expressed as (μmol / L), M Ｂ The methacrylic acid-containing composition according to claim 1, wherein the concentration is 1 to 50,000 μmol / L.

21. Said M Ｂ The methacrylic acid-containing composition according to claim 20, wherein the concentration is 10 to 10,000 μmol / L.

22. The methacrylic acid-containing composition according to claim 1, wherein the molecular weight of component A1 is 2000 or less.

23. The methacrylic acid-containing composition according to claim 5, wherein the molecular weight of component A21 is 1000 or less.

24. The methacrylic acid-containing composition according to claim 5, wherein the molecular weight of component A3 is 2000 or less.

25. The methacrylic acid-containing composition according to claim 5, wherein the molecular weight of component A4 is 1000 or less.

26. The methacrylic acid-containing composition according to claim 1, wherein the molecular weight of component A5 is 1000 or less.

27. The methacrylic acid-containing composition according to claim 5, wherein the molecular weight of component A6 is 1000 or less.

28. The methacrylic acid-containing composition according to claim 1, further comprising, as component B, at least one selected from the group consisting of phenolic compounds, quinone compounds, nitrobenzene compounds, N-oxyl compounds, amine compounds, phosphorus-containing compounds, sulfur-containing compounds, iron-containing compounds, copper-containing compounds, and manganese-containing compounds.

29. The methacrylic acid-containing composition according to claim 1, further comprising, as component B, at least one selected from the group consisting of phenolic compounds, N-oxyl compounds, amine compounds, phosphorus-containing compounds, and sulfur-containing compounds.

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

31. The methacrylic acid-containing composition according to claim 1, further comprising, as component B, at least one selected from the group consisting of 4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl, N,N-diphenylamine, N-nitrosodiphenylamine, triphenylphosphite, and phenothiazine.

32. The methacrylic acid-containing composition according to claim 1, wherein the concentration of methacrylic acid is 98.50 to 99.99% by mass.

33. The methacrylic acid-containing composition according to claim 1, which does not contain diacetyl, or contains diacetyl at a concentration of 55 μmol / L or less.

34. A method for producing a methacrylic acid ester, comprising esterifying the methacrylic acid in a methacrylic acid-containing composition according to any one of claims 1 to 33.

35. A polymerizable composition containing the methacrylic acid-containing composition according to any one of claims 1 to 33.

36. The polymerizable composition according to claim 35, further comprising a monomer copolymerizable with methacrylic acid.

37. A method for producing a methacrylic acid polymer, comprising polymerizing a polymerizable composition containing the methacrylic acid-containing composition described in any one of claims 1 to 33.

38. The manufacturing method according to claim 37, wherein the polymerizable composition further contains a monomer copolymerizable with methacrylic acid.

39. The manufacturing method according to claim 38, wherein the polymerizable composition contains 50 parts by mass or more of a monomer copolymerizable with methacrylic acid per 100 parts by mass of the polymerizable composition.

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