Monomer composition, method for producing methacrylic resin composition, methacrylic resin composition, and resin molding

Abstract

To provide a monomer composition excellent in storage stability, and to provide a methacrylic resin composition and a resin molding which are excellent in heat resistance and capable of suppressing thermal shrinkage.SOLUTION: The monomer composition contains methyl methacrylate, a component A represented by formula (1), a component B represented by formula (2), and at least one compound selected from diacetyl, a nitrile compound, a sulfide compound, a disulfide compound, and thiophene (component C). The concentration of the component A is more than 20 mass ppm and less than 2,000 mass ppm. (R1-R3 are each H, a C1-5 alkyl group or a C1-6 alkoxy group; R4-R5 are each H or a C1-5 alkyl group; and R6 is a C1-5 alkyl group.)SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a monomer composition, a method for producing a methacrylic resin composition, a methacrylic resin composition, and a resin molded article. [Background technology]

[0002] Methyl methacrylate (hereinafter, also referred to as "MMA") is known to be an extremely useful substance used as a raw material for various types of polymers for various applications. For example, methacrylic resins obtained by polymerization of MMA have excellent transparency, heat resistance, and weather resistance, and also have well-balanced performance in terms of resin properties such as mechanical strength, thermal properties, and moldability. Due to such excellent properties, they are used in many applications, such as vehicle components, medical components, toys, liquid containers, optical materials, optical fibers, signs, displays, decorative components, architectural components, and face plates of electronic devices, and are particularly used in light-transmitting components.

[0003] As a method for producing a methacrylic resin, for example, a method of solution polymerization of a polymerizable composition containing MMA using a solvent such as benzene or toluene is known (Patent Documents 1 to 3). MMA, which is used as a raw material for methacrylic resins, generates color-causing substances such as methyl pyruvate during storage, which can reduce the transparency of methacrylic resins produced using the MMA. This reduction in transparency has a significant impact on the quality of the parts subsequently molded, and it is therefore necessary to reduce or remove the color-causing substances at the stage of the monomer composition. Thus, a method has been proposed in which (meth)acrylic esters such as MMA are purified to remove color-causing substances such as methyl pyruvate (Patent Documents 4 and 5). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 63-172709 [Patent Document 2] Patent No. 3227209 [Patent Document 3] JP 2001-151811 A [Patent Document 4] Patent No. 4942878 [Patent Document 5] Patent No. 3672818 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the methacrylic resin compositions and resin molded articles obtained using the conventional techniques such as those described in Patent Documents 1 to 3 have insufficient heat resistance, and it is difficult to sufficiently suppress thermal shrinkage. Furthermore, although the techniques described in Patent Documents 4 and 5 can remove methyl pyruvate and suppress coloration of the methacrylic resin composition and the resin molded article, the production process becomes complicated because purification is required.

[0006] An object of the present invention is to provide a monomer composition capable of producing a methacrylic resin composition having excellent storage stability, excellent heat resistance, and suppressed thermal shrinkage, as well as a methacrylic resin composition and a resin molded article using the monomer composition. [Means for solving the problem]

[0007] The present invention includes the following configurations. [1] A monomer composition comprising methyl methacrylate and an aromatic compound (component A) represented by the following formula (1): A monomer composition, in which, when a concentration of the component A relative to the total mass of the monomer composition is designated as XA (ppm by mass), the concentration of the component A is more than 20 ppm by mass and less than 2000 ppm by mass, and the monomer composition further comprises an ester compound having an α-hydrogen (component B) represented by the following formula (2), and at least one compound selected from the group consisting of diacetyl, a nitrile compound, a sulfide compound, a disulfide compound, and a thiophene (component C): [ka] (In the above formula (1), R 1 , R 2 and R 3 are each independently a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. [ka] (In the above formula (2), R 4 and R 5 are each independently a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and R 6 is an alkyl group having 1 to 5 carbon atoms. [2] The monomer composition according to [1], wherein XA is 20 to 1000 ppm by mass. [3] The monomer composition according to [1], wherein XA is 20 to 500 ppm by mass. [4] The monomer composition according to any one of [1] to [3], wherein the component A contains an aromatic compound having a boiling point of 90°C to 150°C. [5] The monomer composition according to any one of [1] to [3], wherein the component A contains an aromatic compound having a boiling point of 95°C to 120°C. [6] The monomer composition according to any one of [1] to [5], wherein the component A contains at least one selected from the group consisting of xylene, ethylbenzene and toluene. [7] The monomer composition according to any one of [1] to [6], wherein the component A contains toluene. [8] The monomer composition according to any one of [1] to [7], wherein the component B is isobutyl isobutyrate, methyl isovalerate, methyl 2-methylbutyrate, ethyl acetate, methyl butyrate, and isoamyl isobutyrate. [9] The monomer composition according to any one of [1] to [8], wherein the nitrile compound is acetonitrile, methacrylonitrile, or isobutyronitrile.

[10] The monomer composition according to any one of [1] to [9], wherein the sulfide compound and the disulfide compound are dimethyl sulfide, dimethyl disulfide and ethylene sulfide.

[11] The monomer composition according to any one of [1] to

[10] , wherein, when a concentration of the component B relative to a total mass of the monomer composition is XB (ppm by mass), the XB is 1 to 10,000 ppm by mass.

[12] The monomer composition according to any one of [1] to

[11] , wherein XB / XA is 0.001 to 1000, where XB is a concentration of the component B relative to the total mass of the monomer composition (ppm by mass).

[13] The monomer composition according to any one of [1] to

[12] , wherein a concentration of the methyl methacrylate relative to the total mass of the monomer composition is defined as XM (mass%), and the XM is 85 mass% or more.

[14] The monomer composition according to any one of [1] to

[13] , further comprising an acrylic acid ester.

[15] The monomer composition according to

[14] , wherein the acrylic ester is at least one selected from the group consisting of methyl acrylate, ethyl acrylate, and n-butyl acrylate.

[16] The monomer composition according to any one of [1] to

[15] , further containing styrene.

[17] A method for producing a methacrylic resin composition, comprising a step of radically polymerizing a polymerizable composition containing the monomer composition according to any one of [1] to

[16] .

[18] A methacrylic resin composition comprising a polymer of the monomer composition according to any one of [1] to

[16] .

[19] A methacrylic resin composition comprising a methacrylic polymer and an aromatic compound (component A) represented by the following formula (1): A methacrylic resin composition, wherein when a concentration of the component A relative to the total mass of the methacrylic resin composition is defined as YA (ppm by mass), the YA is more than 20 ppm by mass and less than 2000 ppm by mass. [ka] (In the above formula (1), R 1 , R 2 and R 3 are each independently a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms.

[20] The methacrylic resin composition according to

[19] , wherein the YA is 20 to 1,000 ppm by mass.

[21] The methacrylic resin composition according to

[19] , wherein the YA is 20 to 500 ppm by mass.

[22] The methacrylic resin composition according to any one of

[19] to

[21] , wherein Component A contains an aromatic compound having a boiling point of 90°C to 150°C.

[23] The methacrylic resin composition according to any one of

[19] to

[22] , wherein the component A contains an aromatic compound having a boiling point of 95°C to 120°C.

[24] The methacrylic resin composition according to any one of

[19] to

[23] , wherein the component A contains at least one selected from the group consisting of xylene, ethylbenzene, and toluene.

[25] The methacrylic resin composition according to any one of

[19] to

[24] , further comprising an ester compound (component B) having an α-hydrogen atom, represented by the following formula (2): [ka] (In the above formula (2), R 4 and R 5 are each independently a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and R 6 is an alkyl group having 1 to 5 carbon atoms.

[26] The methacrylic resin composition according to any one of

[25] , wherein a concentration of the component B relative to the total mass of the methacrylic resin composition is defined as YB (ppm by mass), and the YB is 1 to 10,000 ppm by mass.

[27] The methacrylic resin composition according to either

[25] or

[26] , wherein YB / YA is 0.001 to 1000, where YB is a concentration of the component B relative to the total mass of the methacrylic resin composition (ppm by mass).

[28] The methacrylic resin composition according to any one of

[19] to

[27] , further comprising at least one compound selected from the group consisting of diacetyl, a nitrile compound, a sulfide compound, a disulfide compound, and a thiophene (component C).

[29] The methacrylic resin composition according to any one of

[19] to

[28] , wherein the methacrylic polymer contains 50 to 100 mass% of repeating units derived from methyl methacrylate, based on the total mass of the methacrylic polymer.

[30] The methacrylic resin composition according to any one of

[19] to

[29] , wherein the methacrylic polymer contains 50 to 100 mass% of repeating units derived from methyl methacrylate and 0 to 50 mass% of repeating units derived from an acrylic ester, based on the total mass of the methacrylic polymer.

[31] The methacrylic resin composition according to any one of

[19] to

[28] , wherein the methacrylic polymer contains 50 to 100% by mass of repeating units derived from methyl methacrylate and 0 to 50% by mass of repeating units derived from styrene.

[32] A resin molded product comprising the methacrylic resin composition according to any one of

[19] to

[29] .

[33] A vehicle part comprising the resin molded article according to

[32] .

[34] A toy comprising the resin molded article described in

[32] .

[35] A signboard comprising the resin molding described in

[32] .

[36] A building material comprising the resin molded article according to

[32] .

[37] A sanitary part comprising the resin molded article according to

[32] .

[38] A cosmetic container comprising the resin molded article according to

[32] .

[39] An optical member comprising the resin molded article according to

[32] . Effect of the Invention

[0008] According to the present invention, a monomer composition having excellent storage stability is provided, and further, a methacrylic resin composition having excellent heat resistance and capable of suppressing thermal shrinkage, and a resin molded article are provided. [Brief description of the drawings]

[0009] [Figure 1] FIG. 2 is an explanatory diagram showing the measurement positions of the dimensional change rate of a test piece in the heat resistance evaluation of the methacrylic resin composition of the examples. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] As used in the specification and claims, the following terms have the following definitions: "Monomer" means a compound that has a polymerizable carbon-carbon double bond. The "repeating unit based on a monomer" is a general term for an atomic group formed directly by polymerization of one monomer molecule, and an atomic group obtained by chemically converting a part of the above-mentioned atomic group. The term "(meth)acrylate" refers to at least one selected from "acrylate" and "methacrylate". "(Meth)acrylic acid" means at least one selected from "acrylic acid" and "methacrylic acid". "(Meth)acryloyl" means at least one selected from "acryloyl" and "methacryloyl". In this specification, a numerical range expressed with "~" means a range that includes the numerical values ​​before and after "~" as the lower and upper limits, and "A~B" means A or more and B or less.

[0011] Hereinafter, an embodiment of the present invention will be described, however, the present invention is not limited to the following.

[0012] [Monomer composition] The monomer composition according to the embodiment contains methyl methacrylate (MMA) and an aromatic compound (component A) described below, and when the concentration of component A relative to the total mass of the monomer composition is defined as XA (ppm by mass), XA is more than 20 ppm by mass and less than 2000 ppm by mass. The monomer composition further contains an ester compound having an α-hydrogen (component B) and at least one compound selected from the group consisting of diacetyl, a nitrile compound, a sulfide compound, a disulfide compound, and a thiophene (component C).

[0013] (Methyl methacrylate) MMA can be produced by, for example, the acetone cyanohydrin method, the new acetone cyanohydrin method, the C4 direct oxidation method, the direct meta method, the ethylene method, the new ethylene method, etc. It may also be MMA obtained by recycling. The MMA contained in the monomer composition is preferably MMA produced by the C4 direct oxidation method or MMA obtained by recycling, more preferably MMA produced by the C4 direct oxidation method using biomass-derived isobutanol as a starting material or MMA obtained by recycling, and particularly preferably MMA obtained by recycling.

[0014] (Component A) Component A is an aromatic compound represented by the following formula (1).

[0015] [ka]

[0016] In the above formula (1), R 1 , R 2 and R 3 are each independently a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms.

[0017] The monomer composition contains a specific amount of component A and at least one compound selected from components B and C, and thus the production of methyl pyruvate, an oxidation product of MMA, is suppressed in the monomer composition during storage, resulting in a monomer composition with excellent storage stability. The reason why component A provides excellent storage stability is not necessarily clear, but is presumed to be as follows.

[0018] During storage of a monomer composition containing MMA, ultraviolet light-induced radicals, such as hydroxyl radicals, are generated when oxygen molecules absorb ultraviolet light from sunlight, and these radicals can oxidize MMA to produce methyl pyruvate. In contrast, aromatic compounds are π-conjugated compounds having a benzene ring, and therefore can absorb ultraviolet light, with the absorption wavelength and absorption intensity varying depending on the type of substituent. The aromatic compound of component A having the structure represented by formula (1) has an appropriate bulkiness and can absorb ultraviolet light of a wide range of wavelengths. In addition, by bonding an alkyl group or alkoxy group having an appropriate electron-donating property to the benzene ring, it can absorb ultraviolet light of an even wider range of wavelengths. In this way, it is believed that component A contained in the monomer composition absorbs ultraviolet light and suppresses the generation of hydroxyl radicals, thereby suppressing the oxidation of MMA to generate methyl pyruvate. Furthermore, by including at least one compound selected from components B and C, the generation of methyl pyruvate can be further suppressed.

[0019] R in the above formula (1) 1 ~R 3 may be the same or different. R 1 ~R 3 At least one of these is preferably an alkyl group.

[0020] In the formula (1), R 1 ~R 3 If the steric hindrance of is large, the benzene ring will be distorted and it will be difficult to maintain the π-conjugated system. 1 ~R 3 satisfies the above condition, the component A has an appropriate bulkiness and maintains the π-conjugated system. Therefore, the component A has the property of absorbing ultraviolet light over a wide wavelength range, and the effects of the present invention can be obtained.

[0021] R 1 ~R 3 The alkyl group may be linear or branched, or may have a ring. R 1 ~R 3 The alkyl group has 1 to 5 carbon atoms, and preferably 1 to 3 carbon atoms. R 1 ~R 3Examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, an s-butyl group, a t-butyl group, an n-pentyl group, an isopentyl group, a cyclopentyl group, etc. Among these, a methyl group and an ethyl group are preferable, and a methyl group is more preferable.

[0022] R 1 ~R 3 The alkoxy group may be linear or branched, or may have a ring. R 1 ~R 3 The alkoxy group has 1 to 6 carbon atoms, and preferably 1 to 3 carbon atoms. R 1 ~R 3 Examples of the alkoxy group include a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, an n-butoxy group, an isobutoxy group, an s-butoxy group, a t-butoxy group, an n-pentoxy group, an isopentoxy group, a phenoxy group, etc. Among these, a methoxy group and an ethoxy group are preferable.

[0023] From the viewpoint of increasing the absorbance of ultraviolet light and suppressing the generation of hydroxyl radicals, R 1 ~R 3 As the group, a hydrogen atom or an alkyl group having 1 to 5 carbon atoms is preferable, a hydrogen atom, a methyl group or an ethyl group is more preferable, and a hydrogen atom or a methyl group is particularly preferable.

[0024] Specific examples of component A include toluene, xylene (o-xylene, m-xylene, p-xylene), ethylbenzene, n-propylbenzene, cumene, t-butylbenzene, mesitylene, etc. Component A may be used alone or in combination of two or more kinds. Component A preferably contains at least one selected from xylene, ethylbenzene, and toluene, more preferably contains xylene or toluene, even more preferably contains toluene, and particularly preferably is toluene.

[0025] From the viewpoint of preventing evaporation during molding, component A preferably contains an aromatic compound having a boiling point of 90°C to 150°C, and more preferably contains an aromatic compound having a boiling point of 95°C to 120°C.

[0026] (Component B) The monomer composition according to the embodiment preferably further contains an ester compound (component B) having an α-hydrogen, represented by the following formula (2).

[0027] [ka]

[0028] In the formula (2), R 4 and R 5 are each independently a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and R 6 is an alkyl group having 1 to 5 carbon atoms.

[0029] In this specification, "α hydrogen" refers to a hydrogen atom bonded to a carbon atom adjacent to the carbon atom of a carbonyl group. When the monomer composition contains component B, the production of methyl pyruvate can be suppressed more efficiently. The reason why component B suppresses the production of methyl pyruvate is not necessarily clear, but is presumed to be as follows.

[0030] Methyl pyruvate is produced by the oxidation of MMA with hydroxyl radicals and oxygen molecules. Component B can trap the radical intermediate produced by the reaction of hydroxyl radicals with MMA, and convert the intermediate back to MMA. This is presumably what inhibits the production of methyl pyruvate.

[0031] The molecular weight of component B is preferably 200 or less. By having a molecular weight of 200 or less, the number of α hydrogens per unit mass in component B can be increased, so that the effects of the present invention can be obtained with a small mass. The molecular weight of component B is more preferably 190 or less, further preferably 180 or less, and particularly preferably 170 or less.

[0032] R in the above formula (2) 4 and R 5 R each independently represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. 4 and R 5 may be the same or different. R in the above formula (2) 6 R represents an alkyl group having 1 to 5 carbon atoms. 6 and R 4 , and R 6 and R 5 may be the same or different. Also, R 4 ~R 6 At least one of these is preferably an alkyl group having 2 to 5 carbon atoms.

[0033] In general, the α-hydrogen of an ester compound has the property of reacting with anions and radicals, but depending on the type of substituent, the reactivity may decrease. 4 , R 5 and R 6 When the above condition is satisfied, the reactivity of the α hydrogen of component B with anions and radicals is maintained, and the effect of suppressing the production of methyl pyruvate is obtained.

[0034] R 4 and R 5 are preferably each independently a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, or an isopropyl group. R 6 is preferably a methyl group, an isobutyl group or an isoamyl group. Since these are highly stable substituents, they can prevent component B from changing into other compounds during storage.

[0035] From the viewpoints of the storage stability of the monomer composition and the quality of the methacrylic resin composition obtained by polymerizing the monomer composition, it is more preferable that component B is at least one selected from the group consisting of isobutyl isobutyrate, methyl isovalerate, methyl 2-methylbutyrate, ethyl acetate, methyl butyrate, and isoamyl isobutyrate. Component B may be used alone or in combination of two or more kinds.

[0036] (Monomers other than methyl methacrylate) The monomer composition according to the embodiment may contain a monomer other than MMA. Examples of the monomer other than MMA include the following monomers (1) to (16). The following monomers (1) to (16) may be used alone or in any combination of two or more kinds in any ratio.

[0037] (1) Methacrylate esters: For example, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, iso-butyl methacrylate, tert-butyl methacrylate, 2-ethylhexyl methacrylate, phenyl methacrylate, or benzyl methacrylate. (2) Acrylic esters: For example, methyl acrylate, ethyl acrylate, n-butyl acrylate, iso-butyl acrylate, tert-butyl acrylate, or 2-ethylhexyl acrylate. (3) Unsaturated carboxylic acids: For example, acrylic acid, methacrylic acid, maleic acid, or itaconic acid. (4) Unsaturated carboxylic acid anhydrides: For example, maleic anhydride, or itaconic anhydride. (5) Maleimide: For example, N-phenylmaleimide, or N-cyclohexylmaleimide. (6) Hydroxy group-containing vinyl monomers: For example, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, or 2-hydroxypropyl methacrylate. (7) Vinyl ester: For example, vinyl acetate, or vinyl benzoate. (8) Vinyl chloride, vinylidene chloride, or their derivatives. (9) Nitrogen-containing vinyl monomers: For example, methacrylamide, or acrylonitrile. (10) Epoxy group-containing monomer: For example, glycidyl acrylate, or glycidyl methacrylate. (11) Aromatic vinyl monomers: For example, styrene, or alpha-methylstyrene. (12) Alkanediol di(meth)acrylate: For example, 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. (13) Polyoxyalkylene glycol di(meth)acrylate: For example, 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. Here, "(meth)acrylate" means at least one selected from "acrylate" and "methacrylate". (14) Vinyl monomers having two or more ethylenically unsaturated bonds in the molecule: For example, divinylbenzene. (15) Unsaturated polyester prepolymers obtained from at least one polycarboxylic acid including an ethylenically unsaturated polycarboxylic acid and at least one diol. (16) Vinyl ester prepolymers obtained by modifying the terminals of epoxy groups with acrylic.

[0038] The methacrylic polymer contained in the methacrylic resin composition described later is preferably a copolymer containing a repeating unit derived from MMA and a repeating unit derived from a vinyl monomer copolymerizable with MMA, and more preferably contains a repeating unit derived from an acrylic ester or a repeating unit derived from styrene as the repeating unit derived from the vinyl monomer. Therefore, the monomer composition according to the embodiment preferably further contains an acrylic ester or styrene as a monomer other than MMA. The acrylic ester is preferably at least one selected from the group consisting of methyl acrylate, ethyl acrylate, and n-butyl acrylate.

[0039] (Component C) The monomer composition according to the embodiment preferably further contains one or more compounds (component C) selected from diacetyl, a nitrile compound, a sulfide compound, a disulfide compound, and thiophene, in addition to the monomer, component A, and component B. One type of component C may be used alone, or two or more types may be used in combination. The composition may contain either one of the components B and C, or may contain both of them.

[0040] Preferable examples of component C include impurities such as diacetyl produced in the production process of MMA, nitrile compounds such as acetonitrile, methacrylonitrile, and isobutyronitrile, sulfide compounds, disulfide compounds such as dimethyl sulfide, dimethyl disulfide, and ethylene sulfide, and other sulfur compounds such as thiophene.

[0041] When the monomer composition according to the embodiment contains diacetyl, from the viewpoint of reducing coloration of the monomer composition, the concentration of diacetyl relative to the total mass of the monomer composition 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. When converted to mass ppm, it is preferably 5 mass ppm or less, more preferably 2 mass ppm or less, even more preferably 1 mass ppm or less, and particularly preferably 0.1 mass ppm or less. The lower limit of the concentration of diacetyl is not particularly limited, but can be, for example, 0.01 mass ppm. In addition, when the monomer composition according to the embodiment also contains component C other than diacetyl, the concentration of component C relative to the total mass of the monomer composition is preferably 100 mass ppm or less, more preferably 50 mass ppm or less, even more preferably 10 mass ppm or less, and particularly preferably 1 mass ppm or less. The lower limit of the concentration of component C is not particularly limited, but can be, for example, 0.01 mass ppm.

[0042] (Component D) The monomer composition according to the embodiment may further contain a compound other than the monomer, component A, component B and component C (component D). Examples of component D include known additives such as polymerization inhibitors, release agents, heat stabilizers, lubricants, plasticizers, antioxidants, antistatic agents, light stabilizers, ultraviolet absorbers, flame retardants, flame retardant assistants, fillers, pigments, dyes, silane coupling agents, leveling agents, defoamers, and fluorescent agents. Component D may be used alone or in combination of two or more.

[0043] (Concentration of each component) When the concentration of MMA relative to the total mass in the monomer composition is designated as XM (mass%), XM is preferably 85 mass% or more, more preferably 90 mass% or more, further preferably 95 mass% or more, and particularly preferably 97 mass% or more. XM is usually 99.99 mass% or less, and may be 99.98 mass% or less or 99.97 mass% or less. Therefore, XM is in the range of, for example, 85 to 99.99 mass %, 90 to 99.98 mass %, 95 to 99.97 mass %, 97 to 99.97 mass %, and 97 to 99.97 mass %.

[0044] When the concentration of component A relative to the total mass of the monomer composition is designated as XA (ppm by mass), XA is more than 20 ppm by mass and less than 2000 ppm by mass. If XA is more than 20 ppm by mass, the production of methyl pyruvate during storage is suppressed, resulting in a monomer composition with excellent storage stability. When XA is less than 2000 ppm by mass, when a methacrylic resin composition and a resin molded article are produced using the monomer composition, they are less likely to undergo heat shrinkage and heat resistance can be maintained.

[0045] The reason why the methacrylic resin composition becomes less susceptible to heat shrinkage by adjusting the XA content to less than 2000 ppm by mass is not necessarily clear, but is presumed to be as follows. If an aromatic compound with a skeleton different from that of MMA is included, the aromatic compound acts as a plasticizer, which disentangles the molecular chains of the methacrylic resin, making it more likely to deform. For this reason, it is believed that if component A1 is 2000 ppm by mass or more, the methacrylic resin composition is more likely to shrink due to heat. On the other hand, if XA is less than 2000 ppm by mass, it is presumed that the function of component A1 as a plasticizer is reduced, making the composition less likely to shrink due to heat.

[0046] XA is preferably more than 20 ppm by mass, more preferably 60 ppm by mass or more, even more preferably 100 ppm by mass or more, particularly preferably 200 ppm by mass or more, and most preferably 250 ppm by mass or more. XA is preferably 1000 ppm by mass or less, more preferably 900 ppm by mass or less, even more preferably 800 ppm by mass or less, particularly preferably 700 ppm by mass or less, and most preferably 500 ppm by mass or less. The preferable lower limit and upper limit of XA can be arbitrarily combined, and for example, it is preferably from 20 to 1000 ppm by mass, and more preferably from 20 to 500 ppm by mass.

[0047] When the monomer composition according to the embodiment contains component B, when the concentration of component B relative to the total mass of the monomer composition is XB (ppm by mass), XB is preferably 1 ppm by mass or more, more preferably 10 ppm by mass or more, and even more preferably 100 ppm by mass or more. If XB is equal to or more than the lower limit, the storage stability of the monomer composition is improved. In addition, XB is preferably 10,000 ppm by mass or less, more preferably 5,000 ppm by mass or less, and even more preferably 1,000 ppm by mass or less. If XB is equal to or less than the upper limit, the light stability of the methacrylic resin composition and the resin molded product produced using the monomer composition is likely to be excellent. The preferable lower limit and upper limit of XB can be arbitrarily combined, and for example, a range of 1 to 10,000 ppm by mass is preferable.

[0048] From the viewpoint of improving the storage stability of the monomer composition, XB / XA is preferably 0.001 or more, more preferably 0.5 or more, and even more preferably 2 or more, while it is preferably 1000 or less, more preferably 500 or less, and even more preferably 300 or less. The preferred lower and upper limits of XB / XA can be arbitrarily combined, and for example, 0.001 to 1000 is preferable.

[0049] When the monomer composition according to the embodiment contains a monomer other than MMA, the concentration of the monomer other than MMA relative to the total mass of the monomer composition is preferably 0 to 15% by mass. The lower limit of the concentration of the monomer other than MMA is more preferably 1% by mass or more, and the upper limit is more preferably 10% by mass or less. The preferable lower and upper limits of the concentration of the monomer other than MMA can be combined in any desired manner.

[0050] The water content of the monomer composition is preferably 5000 mass ppm or less, more preferably 4000 mass ppm or less, further preferably 3000 mass ppm or less, particularly preferably 2000 mass ppm or less, and most preferably 1000 mass ppm or less, based on the total mass of the monomer composition. When the water content of the monomer composition is equal to or less than the upper limit, the physical properties of the methacrylic resin composition obtained by polymerizing the monomer composition can be better maintained. The lower limit of the water content in the monomer composition is 0 ppm by mass.

[0051] (Analysis of Monomer Composition) The concentrations of component A, component B, monomers other than MMA, component C, and water in the monomer composition can be calculated, for example, from the amounts charged when the monomer composition is prepared.

[0052] When the charged amounts are unknown, it can be confirmed that the monomer composition contains component A, component B, component C and water by, for example, GC-MS measurement. If the GC-MS chart of the monomer composition has a peak at the same retention time as a standard specimen of component A, and the m / z value detected in the mass spectrum of the peak matches the exact mass of component A, the monomer composition can be determined to contain component A. If a standard specimen of component A cannot be obtained, the peak can be determined to be a component A peak if the mass spectrum pattern of the peak appearing in the GC-MS chart of the monomer composition matches the mass spectrum pattern of component A recorded in the mass spectrum database. In other words, it can be determined that the monomer composition contains component A. Examples of mass spectrum databases include NIST20, NIST17, NIST14, and NIST14s. In addition, if the volatility is low and detection by GC-MS measurement is not possible, it can be detected using LC-MS. The inclusion of components B, C, and water can also be confirmed by the same method.

[0053] The MMA concentration can be calculated, for example, by subjecting the monomer composition to GC-FID measurement, quantifying it using the area percentage method, and correcting it using the water concentration quantified using a Karl Fischer moisture meter.

[0054] The content (concentration) of component A can be determined, for example, by subjecting the monomer composition to GC or GC-MS measurement and using the internal standard method or absolute calibration curve method. If a standard sample of component A cannot be obtained and quantification cannot be performed using the internal standard method or absolute calibration curve method, any organic compound with a known concentration can be subjected to GC-FID measurement under the same conditions as the monomer composition, and the content of component A can be calculated using the following formula.

[0055]

number

[0056] Here, N is the number of carbon atoms in one molecule of an organic compound with a known concentration, N A is the number of carbon atoms contained in one molecule of component A, S A is the peak area of ​​component A, S is the peak area of ​​the organic compound of known concentration, and M is the content (ppm by mass) of the organic compound of known concentration. In addition, when the volatility is low and quantification by GC measurement is not possible, chromatographic methods such as LC can be used for quantification. The contents of components B and C can be calculated in the same manner as for component A. Furthermore, the presence and concentration of water in the monomer composition can be confirmed by the Karl Fischer method.

[0057] (Method for Producing Monomer Composition) The monomer composition according to the embodiment can be produced, for example, by using MMA containing component A, component B, or component C, or by adding component A, component B, or component C to MMA, and may further contain a monomer other than MMA as desired. The monomer composition is preferably produced using recycled MMA or MMA produced by a C4 direct oxidation method, more preferably using recycled MMA or MMA produced by a C4 direct oxidation method using biomass-derived isobutanol as a starting material, and particularly preferably recycled MMA. Note that the MMA used may be a commercially available product.

[0058] Components A, B, and C may be commercially available products or may be synthesized by known methods. When using MMA produced by the above-mentioned method, components A, B, and C, and optionally further monomers other than MMA, may be added as raw materials or during the manufacturing process to produce a monomer composition. When components A, B, or C are produced as by-products in the MMA production process, a part of the produced components A, B, or C may be left to produce a monomer composition.

[0059] [Methacrylic resin composition] The methacrylic resin composition according to the embodiment contains a methacrylic polymer and a component A, and when the concentration of the component A relative to the total mass of the methacrylic resin composition is defined as YA (ppm by mass), YA is more than 20 ppm by mass and less than 2000 ppm by mass. The form of the methacrylic resin composition is not particularly limited, but is usually a solid.

[0060] (Methacrylic polymer) In this specification, a methacrylic polymer is a polymer containing repeating units derived from MMA (hereinafter also referred to as "MMA units"). The methacrylic resin composition according to the embodiment contains a methacrylic polymer, and thus exhibits good transparency. In addition, decomposition due to heat or light is suppressed, and the composition exhibits good thermoformability, heat resistance, and mechanical strength. The methacrylic polymer contained in the methacrylic resin composition may be one type or two or more types.

[0061] The methacrylic polymer is preferably a copolymer containing MMA units and repeating units derived from a vinyl monomer copolymerizable with MMA (hereinafter also simply referred to as "vinyl monomer"). From the viewpoint of heat resistance and light stability of the methacrylic resin composition, it is more preferable that the content of MMA units is 50 to 100 mass% and the content of repeating units derived from vinyl monomers is 0 to 50 mass% relative to the total mass of the methacrylic polymer. The content of MMA units is more preferably 60 mass% or more, even more preferably 70 mass% or more, particularly preferably 80 mass% or more, and most preferably 90 mass% or more. On the other hand, the content of repeating units derived from vinyl monomers is more preferably 40 mass% or less, even more preferably 30 mass% or less, particularly preferably 20 mass% or less, and most preferably 10 mass% or less.

[0062] When the methacrylic polymer is a copolymer, the sequence of the copolymer is not particularly limited and may be, for example, a random copolymer, a block copolymer, an alternating copolymer, or the like, with a random copolymer being preferred.

[0063] For the MMA used in the methacrylic polymer, the explanation given in relation to the monomer composition is applicable as is. When the methacrylic polymer is a copolymer containing a repeating unit derived from a vinyl monomer, the vinyl monomer is preferably an acrylic acid ester or styrene, which improves the light stability of the methacrylic resin composition.

[0064] When the vinyl monomer is an acrylic acid ester, the methacrylic polymer preferably contains 50 to 100% by mass of MMA units and 0 to 50% by mass of repeating units derived from an acrylic acid ester. When the vinyl monomer is styrene, the methacrylic polymer preferably contains 50 to 100% by mass of MMA units and 0 to 50% by mass of repeating units derived from styrene.

[0065] The acrylic acid ester is preferably an acrylic acid ester having an alkyl group having 1 to 6 carbon atoms in the side chain, and examples thereof include methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, and t-butyl acrylate. These may be used alone or in combination of two or more. Among these, from the viewpoint of the light stability of the methacrylic resin composition, at least one selected from the group consisting of methyl acrylate, ethyl acrylate, and n-butyl acrylate is preferred, and methyl acrylate and ethyl acrylate are more preferred. The vinyl monomers may be used alone or in combination of two or more kinds.

[0066] The methacrylic polymer may contain repeating units derived from a polyfunctional monomer containing two or more radically polymerizable functional groups in one molecule, within the range in which the effects of the invention can be obtained, thereby improving the solvent resistance or chemical resistance, etc.

[0067] The radical polymerizable functional group is not particularly limited as long as it has a carbon-carbon double bond and is radically polymerizable. Specific examples include vinyl groups, allyl groups, (meth)acryloyl groups, and (meth)acryloyloxy groups. In particular, (meth)acryloyl groups are preferred from the viewpoint of excellent storage stability of a compound having a radical polymerizable functional group and easy control of the polymerizability of the compound. In addition, each radical polymerizable functional group in a monomer having two radical polymerizable functional groups may be the same or different.

[0068] Examples of the polyfunctional monomer include, but are not limited to, allyl methacrylate, allyl acrylate, ethylene glycol di(meth)acrylate, ethylene glycol tri(meth)acrylate, neopentyl glycol di(meth)acrylate, and trimethylolpropane tri(meth)acrylate. These may be used alone or in combination of two or more. As the polyfunctional monomer, from the viewpoint of obtaining better solvent resistance and chemical resistance, one selected from ethylene glycol di(meth)acrylate and neopentyl glycol di(meth)acrylate is more preferable, and ethylene glycol di(meth)acrylate is even more preferable.

[0069] (Component A) Component A is as described above. The methacrylic resin composition may contain one type or two or more types of component A.

[0070] (Component B) The methacrylic resin composition according to the embodiment preferably further contains Component B. Component B is as described above. The methacrylic resin composition may contain one type or two or more types of component B.

[0071] (Component C) It is preferable that the methacrylic resin composition further contains Component C. Component C is as described above. The composition may contain either one of the components B and C, or may contain both of them.

[0072] (Component D) The methacrylic resin composition may further contain Component D. Component D is as described above.

[0073] (Concentration of each component) When the concentration of the methacrylic polymer relative to the total mass of the methacrylic resin composition is YM (mass%), YM is preferably 95 mass% or more, more preferably 97.5 mass% or more, even more preferably 98 mass% or more, and particularly preferably 99 mass% or more from the viewpoint of good heat resistance. On the other hand, from the viewpoint of obtaining excellent light stability, it is preferably 99.99 mass% or less, more preferably 99.985 mass% or less, even more preferably 99.98 mass% or less, particularly preferably 99.975 mass% or less, particularly preferably 99.97 mass% or less, even more preferably 99.95 mass% or less, and most preferably 99.9 mass% or less. The preferable lower limit and upper limit of YM can be arbitrarily combined. For example, YM may be in the range of 95 to 99.99 mass%, 95 to 99.985 mass%, 97.5 to 99.98 mass%, 97.5 to 99.975 mass%, 98 to 99.97 mass%, 98 to 99.95 mass%, or 99 to 99.9 mass%. When the methacrylic resin composition contains two or more types of methacrylic polymers, YM is the total concentration of the two or more types of methacrylic polymers.

[0074] When the concentration of component A relative to the total mass of the methacrylic resin composition is YA (ppm by mass), YA is more than 20 ppm by mass and less than 2000 ppm by mass. If YA is more than 20 ppm by mass, a resin molded article having excellent transparency can be produced. If YA is less than 2000 ppm by mass, a resin molded article maintaining good heat resistance can be produced.

[0075] The YA is preferably 20 ppm or more, more preferably 60 ppm or more, even more preferably 100 ppm or more, particularly preferably 200 ppm or more, and most preferably 250 ppm or more. The YA is preferably 1000 ppm by mass or less, and more preferably 500 ppm by mass or less. The preferred lower and upper limits of YA can be arbitrarily combined, and are, for example, preferably 20 to 1000 ppm by mass, more preferably 20 to 500 ppm by mass.

[0076] When the methacrylic resin composition according to the embodiment contains component B, the concentration of component B relative to the total mass of the methacrylic resin composition is defined as YB (ppm by mass), and YB is preferably 1 ppm by mass or more, more preferably 2 ppm by mass or more, and even more preferably 3 ppm by mass or more. If YB is equal to or more than the lower limit, a resin molded product having excellent transparency can be produced. In addition, YB is preferably 10,000 ppm by mass or less, more preferably 5,000 ppm by mass or less, even more preferably 1,000 ppm by mass or less, particularly preferably 500 ppm by mass or less, and most preferably 100 ppm by mass or less. If YB is equal to or less than the upper limit, a resin molded product having good heat resistance can be produced. The preferable lower limit and upper limit of YB can be arbitrarily combined, and for example, a range of 1 to 10,000 ppm by mass is preferable.

[0077] When the methacrylic resin composition according to the embodiment contains diacetyl as component C, the concentration of diacetyl relative to the total mass of the methacrylic resin composition 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, from the viewpoint of reducing coloration of the monomer composition. When converted to mass ppm, it is preferably 5 mass ppm or less, more preferably 2 mass ppm or less, even more preferably 1 mass ppm or less, and particularly preferably 0.1 mass ppm or less. The lower limit of the concentration of diacetyl is not particularly limited, but can be, for example, 0.01 mass ppm. In addition, when the methacrylic resin composition according to the embodiment contains a component C other than diacetyl, the concentration of the component C relative to the total mass of the methacrylic resin composition is preferably 100 mass ppm or less, more preferably 50 mass ppm or less, even more preferably 10 mass ppm or less, and particularly preferably 1 mass ppm or less. The lower limit of the concentration of the component C is not particularly limited, but can be, for example, 0.01 mass ppm.

[0078] From the viewpoint of easily producing a resin molded product having excellent transparency and heat resistance, YB / YA is preferably 0.001 or more, more preferably 0.5 or more, and even more preferably 2 or more, while it is preferably 1000 or less, more preferably 500 or less, and even more preferably 300 or less. The preferred lower and upper limits of YB / YA can be arbitrarily combined, and for example, 0.001 to 1000 is preferable.

[0079] (Analysis of Methacrylic Resin Composition) The concentrations of Component A, Component B, and Component C present in the methacrylic resin composition can be measured, for example, by the following method. The methacrylic resin composition is finely crushed, and 0.2 g of the crushed methacrylic resin composition is dissolved in 10 mL of acetone for residual pesticide testing (hereinafter, also simply referred to as "acetone"). Next, 1 mL of the internal standard solution is added to the obtained solution using a volumetric pipette. Here, the internal standard solution used is a 0.1 volume % methyl salicylate / acetone solution. The standard reagent of component A is diluted with acetone to prepare three test solutions with different concentrations of component A, and the internal standard solution is added to create a three-point calibration curve by GC-MS measurement. Using this, the concentration of each component in the methacrylic resin composition is quantified. The concentrations of components B and C can be measured in the same manner as for component A.

[0080] [Methacrylic resin composition manufacturing method] The methacrylic resin composition according to the embodiment can be produced by a method including a step of radically polymerizing a polymerizable composition containing MMA. Examples of the polymerizable composition include a polymerizable composition (M1) containing a raw material composition, component A, and a radical polymerization initiator, or a polymerizable composition (M2) containing a monomer composition according to an embodiment and a radical polymerization initiator, with the polymerizable composition (M2) being preferred. That is, the methacrylic resin composition according to the embodiment preferably contains a polymer of the monomer composition according to the embodiment.

[0081] (Polymerizable composition (M1)) The polymerizable composition (M1) contains a raw material composition, a component A, and a radical polymerization initiator. The polymerizable composition (M1) preferably further contains a component B. In addition, the polymerizable composition (M1) may contain a component C within a range that does not impair the effects of the present invention.

[0082] The raw material composition is also a raw material component of the methacrylic polymer contained in the methacrylic resin composition according to the embodiment. The raw material composition may be a composition containing only MMA, or a composition containing MMA and a vinyl monomer copolymerizable with MMA. The vinyl monomer copolymerizable with MMA is as described above.

[0083] Relative to the total mass of the raw material composition, the content of MMA is preferably 50-100% by mass, and the content of vinyl monomer is preferably 0-50% by mass. The content of MMA is more preferably 60% by mass or more, even more preferably 70% by mass or more, particularly preferably 80% by mass or more, and most preferably 90% by mass or more. The content of vinyl monomer is more preferably 40% by mass or less, even more preferably 30% by mass or less, particularly preferably 20% by mass or less, and most preferably 10% by mass or less.

[0084] The raw material composition may contain a polymer containing MMA units in advance. When the raw material composition contains a polymer, it becomes a viscous liquid (hereinafter also referred to as "syrup"), so that the polymerization time can be shortened and the productivity can be improved. Specific examples of the polymer containing MMA units include polymers containing 50% by mass or more of MMA units and 50% by mass or less of repeating units derived from vinyl monomers relative to the total mass of the polymer, and polymers consisting of 100% by mass of MMA units.

[0085] Examples of methods for obtaining the syrup include a method of dissolving a polymer containing MMA units in a raw material composition, and a method of adding a known radical polymerization initiator to a raw material composition and polymerizing a part of it. The concentration of the raw material composition relative to the total mass of the polymerizable composition (M1) can be in the range of 97.5 to 99.99 mass %.

[0086] The component A contained in the polymerizable composition (M1) may be one type or two or more types. The concentration of component A relative to the total mass of the polymerizable composition (M1) is preferably more than 20 ppm by mass and less than 2000 ppm by mass, more preferably more than 20 ppm by mass and 1000 ppm by mass or less, and even more preferably more than 20 ppm by mass and 500 ppm by mass or less.

[0087] When the polymerizable composition (M1) contains the component B, the polymerizable composition (M1) may contain one type of component B or two or more types of component B. When the polymerizable composition (M1) contains the component B, the concentration of the component B relative to the total mass of the polymerizable composition (M1) is preferably from 1 to 10,000 ppm by mass.

[0088] When the polymerizable composition (M1) contains the component C, the polymerizable composition (M1) may contain one type of component C or two or more types of component C. When the polymerizable composition (M1) contains component C, the concentration of component C relative to the total mass of the polymerizable composition (M1) is preferably 100 mass ppm or less, more preferably 50 mass ppm or less, even more preferably 10 mass ppm or less, and particularly preferably 1 mass ppm or less. The lower limit of the concentration of component C is not particularly limited, but can be, for example, 0.01 mass ppm.

[0089] (Radical polymerization initiator) As the radical polymerization initiator, known ones can be used. As the radical polymerization initiator, for example, known azo compounds such as 2,2'-azobis(isobutyronitrile) and 2,2'-azobis(2,4-dimethylvaleronitrile); known organic peroxides such as t-hexyl peroxypivalate, benzoyl peroxide, and lauroyl peroxide; etc. can be mentioned. These may be used alone or in combination of two or more kinds. If necessary, a known polymerization accelerator such as an amine or mercaptan may be used in combination with the radical polymerization initiator. The concentration of the radical polymerization initiator relative to the total mass of the polymerizable composition (M1) is not particularly limited, and can be, for example, 0.005 to 5 mass %, or may be 0.01 to 1 mass %.

[0090] (Polymerizable composition (M2)) The polymerizable composition (M2) contains the monomer composition according to the embodiment and a known radical polymerization initiator. Examples of the radical polymerization initiator used in the polymerizable composition (M2) include the same ones as those exemplified for the polymerizable composition (M1). The concentration of the radical polymerization initiator relative to the total mass of the polymerizable composition (M2) is not particularly limited, and can be, for example, 0.005 to 5 mass %, or may be 0.01 to 1 mass %.

[0091] (Radical Polymerization Process of Polymerizable Composition) The radical polymerization step of the polymerizable composition may include a syrup preparation step of preparing a syrup by polymerizing a part of the polymerizable composition, and a polymerization step of polymerizing a polymerizable component in the obtained syrup. Note that "polymerizing a part of the polymerizable composition" in the syrup preparation step means polymerization so that the concentration of the polymer is 10 to 80 mass%, preferably 10 to 60 mass%, more preferably 10 to 40 mass%, based on the total mass of the obtained syrup.

[0092] The polymerization temperature when polymerizing the polymerizable composition is not particularly limited, and can be appropriately determined by a person skilled in the art according to well-known techniques. Usually, it is appropriately set in the range of preferably 40 to 180°C, more preferably 50 to 150°C, depending on the type of radical polymerization initiator used. In addition, the polymerizable composition can be polymerized under multiple temperature conditions as necessary. The polymerization time may be appropriately determined depending on the progress of polymerization and curing.

[0093] Examples of the polymerization method for the polymerizable composition include bulk polymerization, suspension polymerization, emulsion polymerization, dispersion polymerization, etc. Among them, the bulk polymerization is preferred from the viewpoint of excellent productivity, since it can produce a methacrylic resin composition and form a resin molded article at the same time. Specific examples of the bulk polymerization method include a method of obtaining a resin molded product by bulk polymerization using a known cast polymerization method, or a method of obtaining a resin molded product by molding a composition produced by bulk polymerization, etc. It is preferable to use a method utilizing cast polymerization from the viewpoint of further improving the heat resistance of the resin molded product by increasing the molecular weight or introducing a crosslinked structure.

[0094] [Resin molding] The resin molded article according to the embodiment includes the methacrylic resin composition according to the embodiment. By molding the methacrylic resin composition, a resin molded article having excellent transparency and heat resistance can be obtained. Examples of the molding method include press molding, injection molding, gas-assisted injection molding, welding molding, extrusion molding, blow molding, film molding, blow molding, multi-layer molding, and melt spinning.

[0095] The resin molded article according to the embodiment may be a molded article containing a methacrylic resin composition, or may be a molded article made only of the methacrylic resin composition. When the resin molded article is a molded article made only of the methacrylic resin composition, the methacrylic resin composition substantially corresponds to both the methacrylic resin composition and the resin molded article.

[0096] The shape of the resin molded body is not particularly limited, but examples thereof include a plate-shaped resin molded body (resin plate), a sheet-shaped resin molded body (resin sheet), granular pellets, etc. The thickness of the resin molded body can be adjusted to any thickness as needed, from a thick plate to a thin film, and can be, for example, 1 to 30 mm.

[0097] Applications of the resin molded articles are not particularly limited, but they can be suitably used for vehicle components, medical components, toys, liquid containers, optical materials, optical fibers, signs, displays, decorative components, architectural components, and face plates of electronic devices. EXAMPLES

[0098] The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to these examples. In the examples and comparative examples, "%" and "ppm" mean "% by mass" and "ppm by mass" unless otherwise specified. In addition, "parts" means "parts by mass".

[0099] The abbreviations and names of the compounds used in the examples and comparative examples are as follows. Methyl methacrylate: Methyl methacrylate (Mitsubishi Chemical Corporation) Toluene (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) The methyl methacrylate (manufactured by Mitsubishi Chemical Corporation) contained toluene at a concentration of 20 ppm by mass and diacetyl at a concentration of 0.5 ppm by mass relative to the total mass of the methyl methacrylate.

[0100] [Analysis of Monomer Composition] The contents of the components of the monomer compositions produced in the Examples and Comparative Examples can be calculated by adding the amounts added shown in Table 1 and the amount of toluene contained in the methyl methacrylate itself. In addition, in the storage stability evaluation described below, the amount of methyl pyruvate in the monomer composition after storage was quantified by the absolute calibration curve method using GC-MS. The measurement conditions for GC-MS are shown below.

[0101] (GC-MS measurement conditions) Equipment: GC-MS measurement equipment (product name: QP-2010SE, manufactured by Shimadzu Corporation) Carrier gas: Helium Ionization method: EI (Electron Ionization) method Column: DB-WAX 60m x 320μm x 1.0μm (Agilent) Heating conditions: hold at 35°C for 10 minutes, heat from 35°C to 150°C at 5°C / min, hold at 150°C for 17 minutes, heat from 150°C to 220°C at 5°C / min, hold at 220°C for 6 minutes. Inlet temperature: 210℃ Interface temperature: 250℃ Ion source temperature: 250℃ Injection mode: Split Split ratio: 50:1 Flow rate: 0.97mL / min Total flow: 52.5mL / min Purge flow rate: 3.0mL / min Control mode: Constant linear velocity Pressure: 26.1KPa Average linear velocity: 25.0cm / sec Injection volume: 1μL Measurement mode: Scan mode m / z detection range: 10-300 Detection time: 70 minutes

[0102] [Storage stability evaluation of monomer composition] The storage stability of the monomer compositions produced in the Examples and Comparative Examples was evaluated by measuring the amount of methyl pyruvate produced in the monomer compositions before heating, in the monomer compositions stored at 50°C for one week, and in the monomer compositions stored at 60°C for three days.

[0103] [Analysis of methacrylic resin composition] The concentrations of the components of the methacrylic resin compositions produced in the Examples and Comparative Examples were calculated by the following method. The obtained methacrylic resin composition was finely crushed, and 0.2 g of the crushed methacrylic resin composition was dissolved in 10 mL of acetone. Next, 1 mL of the internal standard solution was added to the obtained solution using a whole pipette. A 0.1% by volume methyl salicylate / acetone solution was used as the internal standard solution. Three types of test solutions with different concentrations were prepared by diluting the target standard reagent with acetone, and the internal standard solution was added to create a three-point calibration curve by GC-MS measurement. Using this, the concentrations of the components in the methacrylic resin composition were quantified. The measurement conditions for GC-MS are shown below.

[0104] (GC-MS measurement conditions) Equipment: GC HP6890 / MS HP5973 (Agilent) Ionization method: EI (Electron Ionization) method Column: DB-WAX 60m x 250μm x 0.5μm (Agilent) Temperature rise conditions: 70℃(5min)→200℃(5min) Rate=10℃ / min Inlet temperature: 220℃ AUX temperature: 230℃ Ion source temperature: 230℃ Split ratio: 10:1 Flow rate: 2.0mL / min Average linear velocity: 37cm / sec Injection volume: 1μL Measurement mode: SIM

[0105] [Evaluation of heat resistance of methacrylic resin composition] (1) Heat shrinkability Heat shrinkage was used as an index of heat resistance of the methacrylic resin compositions produced in the examples and comparative examples. A test piece of the methacrylic resin composition (length 120 mm × width 12.7 mm × thickness 3 mm) was heated at 100°C for 7 days, and the dimensions in the direction in which the syrup was injected (called MD) and the direction perpendicular to the MD (called TD) were measured before and after heating, and the change rate (%) of each dimension in the MD and TD directions was calculated. Specifically, the change rates (n=2) in the MD direction at (4), (5), and (6) in the figure, and the change rates (n=2) in the TD direction at (1), (2), and (3) in Figure 1 were calculated, and the average values ​​were calculated. The results are shown in Table 2.

[0106] (2) Heat deflection temperature (HDT) As another index of heat resistance of the methacrylic resin compositions produced in the Examples and Comparative Examples, the deflection temperature under load (HDT) was used. HDT was measured in accordance with JIS K 7191 for test pieces of the methacrylic resin compositions (length 120 mm × width 12.7 mm × thickness 3 mm).

[0107] [Example 1] Toluene was used as component A, and 0.025 parts of component A was added to 100 parts of methyl methacrylate as a reagent to prepare a monomer composition with a component A content of 270 ppm by mass.

[0108] [Examples 2 to 3] A monomer composition was prepared in the same manner as in Example 1, except that the amount of toluene added in the monomer composition was changed as shown in Table 1.

[0109] [Comparative Example 1] A monomer composition containing only methyl methacrylate without adding toluene was prepared.

[0110] The monomer compositions obtained in each example were stored at 50°C for one week and at 60°C for three days, and the amount of methyl pyruvate produced in the monomer compositions after storage was measured. The results are shown in Table 1.

[0111] [Table 1]

[0112] As shown in Table 1, the monomer compositions of Examples 1 to 3, which contained an appropriate amount of toluene as component A and further contained diacetyl as component C, produced a small amount of methyl pyruvate after storage and had excellent storage stability. On the other hand, the monomer composition of Comparative Example 1, which contained a small amount of component A, produced a large amount of methyl pyruvate after storage and had poor storage stability.

[0113] [Example 4] Toluene was used as component A, and 0.020 parts of component A was added to 100 parts of methyl methacrylate as a reagent to prepare a monomer composition with a component A content of 220 ppm by mass. The monomer composition was fed into a reactor (polymerization kettle) equipped with a cooling tube, a thermometer, and a stirrer, and after bubbling with nitrogen gas while stirring, heating was started. When the internal temperature of the reactor reached 80°C, 0.12 parts of 2,2'-azobis(2,4-dimethylvaleronitrile) was added as a radical polymerization initiator, and the reactor was further heated until the internal temperature reached 100°C and then maintained for 9 minutes. The reactor was then cooled until the internal temperature reached room temperature to obtain a syrup. The concentration of the polymer in the syrup was 20% by mass relative to the total mass of the syrup. To 100 parts of the obtained syrup, 0.3 parts of t-hexyl peroxypivalate was added as a radical polymerization initiator to obtain a polymerizable composition. Two SUS plates were placed facing each other with a soft resin gasket placed on the end of the SUS plate between them. The polymerizable composition was poured into the space between the SUS plates, which was 4.1 mm apart, and cured by heating at 80°C for 45 minutes and then at 130°C for 30 minutes to obtain a methacrylic resin composition. Next, the obtained methacrylic resin composition was cooled together with the SUS plate, and the SUS plate was removed to obtain a plate-shaped resin molded product having a thickness of 3 mm. The resin molded product was a molded product consisting only of the methacrylic resin composition, and corresponds to both the methacrylic resin composition and the resin molded product.

[0114] [Comparative Example 1] A resin molded article was produced in the same manner as in Example 1, except that the amount of toluene (component A) added was changed as shown in Table 2.

[0115] [Comparative Example 2] A resin molded article was produced in the same manner as in Example 1, except that the amount of toluene (component A) added was changed as shown in Table 2.

[0116] Table 2 shows the evaluation results of the resin molded articles obtained in each example. In Table 2, "MD direction" means the injection direction of the polymerizable composition when pouring the polymerizable composition into the space between the SUS plates, and "TD direction" means the direction parallel to the SUS plates and perpendicular to the MD direction.

[0117] [Table 2]

[0118] As shown in Table 2, the resin molded product of Example 4, which contained an appropriate amount of toluene as component A and further contained diacetyl as component C, had superior heat resistance and suppressed thermal shrinkage compared to the resin molded product of Comparative Example 2, which contained a higher amount of toluene.

Claims

1. A monomer composition comprising methyl methacrylate and an aromatic compound (component A) represented by the following formula (1): A monomer composition, wherein, when a concentration of the component A relative to a total mass of the monomer composition is defined as XA (ppm by mass), the concentration of the component A is more than 20 ppm by mass and less than 2000 ppm by mass, and the monomer composition further comprises an ester compound having an α-hydrogen (component B) represented by the following formula (2), and at least one compound selected from the group consisting of diacetyl, a nitrile compound, a sulfide compound, a disulfide compound, and a thiophene (component C): 【Chemistry 1】 (In the above formula (1), R １ , R ２ and R ３ are each independently a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. 【Chemistry 2】 (In the above formula (2), R ４ and R ５ are each independently a hydrogen atom or an alkyl group having 1 to 5 carbon atoms; R ６ is an alkyl group having 1 to 5 carbon atoms.

2. The monomer composition according to claim 1, wherein the XA is 20 to 1000 ppm by mass.

3. The monomer composition according to claim 1, wherein the XA is 20 to 500 ppm by mass.

4. 2. The monomer composition according to claim 1, wherein the component A comprises an aromatic compound having a boiling point of 90°C to 150°C.

5. 2. The monomer composition according to claim 1, wherein said component A comprises an aromatic compound having a boiling point of 95°C to 120°C.

6. 2. The monomer composition according to claim 1, wherein the component A contains at least one selected from the group consisting of xylene, ethylbenzene and toluene.

7. The monomer composition of claim 1 , wherein component A contains toluene.

8. 2. The monomer composition according to claim 1, wherein said component B is isobutyl isobutyrate, methyl isovalerate, methyl 2-methylbutyrate, ethyl acetate, methyl butyrate and isoamyl isobutyrate.

9. 2. The monomer composition according to claim 1, wherein the nitrile compounds are acetonitrile, methacrylonitrile and isobutyronitrile.

10. 2. The monomer composition according to claim 1, wherein the sulfide compound and disulfide compound are dimethyl sulfide, dimethyl disulfide and ethylene sulfide.

11. The monomer composition according to claim 1, wherein the concentration of said component B relative to the total mass of said monomer composition is XB (ppm by mass), and said XB is 1 to 10,000 ppm by mass.

12. The monomer composition according to claim 1, wherein XB / XA is 0.001 to 1000, where XB is a concentration of the component B relative to the total mass of the monomer composition (ppm by mass).

13. The monomer composition according to claim 1, wherein the concentration of the methyl methacrylate relative to the total mass of the monomer composition is XM (mass%), and the XM is 85 mass% or more.

14. The monomer composition of claim 1 further comprising an acrylic acid ester.

15. The monomer composition according to claim 14, wherein the acrylic ester is at least one selected from the group consisting of methyl acrylate, ethyl acrylate, and n-butyl acrylate.

16. The monomer composition of claim 1 further comprising styrene.

17. A method for producing a methacrylic resin composition, comprising a step of radically polymerizing a polymerizable composition containing the monomer composition according to any one of claims 1 to 16.

18. A methacrylic resin composition comprising a polymer of the monomer composition according to any one of claims 1 to 16.

19. A methacrylic resin composition comprising a methacrylic polymer and an aromatic compound (component A) represented by the following formula (1): A methacrylic resin composition, wherein YA (ppm by mass) is a concentration of the component A relative to the total mass of the methacrylic resin composition, and the YA is more than 20 ppm by mass and less than 2,000 ppm by mass. 【Chemistry 3】 (In the above formula (1), R １ , R ２ and R ３ are each independently a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms.

20. The methacrylic resin composition according to claim 19, wherein the YA is 20 to 1000 ppm by mass.

21. The methacrylic resin composition according to claim 19, wherein the YA is 20 to 500 ppm by mass.

22. The methacrylic resin composition according to claim 19, wherein the component A contains an aromatic compound having a boiling point of 90°C to 150°C.

23. The methacrylic resin composition according to claim 19, wherein the component A contains an aromatic compound having a boiling point of 95°C to 120°C.

24. The methacrylic resin composition according to claim 19, wherein the component A contains at least one selected from the group consisting of xylene, ethylbenzene, and toluene.

25. The methacrylic resin composition according to claim 19, further comprising an ester compound (component B) having an α-hydrogen represented by the following formula (2): 【Chemistry 4】 (In the above formula (2), R ４ and R ５ are each independently a hydrogen atom or an alkyl group having 1 to 5 carbon atoms; R ６ is an alkyl group having 1 to 5 carbon atoms.

26. The methacrylic resin composition according to claim 25, wherein the concentration of the component B relative to the total mass of the methacrylic resin composition is YB (ppm by mass), and the YB is 1 to 10,000 ppm by mass.

27. The methacrylic resin composition according to claim 25, wherein YB / YA is 0.001 to 1000, where YB is the concentration of the component B relative to the total mass of the methacrylic resin composition (ppm by mass).

28. The methacrylic resin composition according to claim 19, further comprising at least one compound selected from the group consisting of diacetyl, a nitrile compound, a sulfide compound, a disulfide compound, and a thiophene (component C).

29. The methacrylic resin composition according to claim 19, wherein the methacrylic polymer contains 50 to 100% by mass of repeating units derived from methyl methacrylate, based on the total mass of the methacrylic polymer.

30. The methacrylic resin composition according to claim 19, wherein the methacrylic polymer contains 50 to 100% by mass of repeating units derived from methyl methacrylate and 0 to 50% by mass of repeating units derived from an acrylic ester, based on the total mass of the methacrylic polymer.

31. The methacrylic resin composition according to claim 19, wherein the methacrylic polymer contains 50 to 100% by mass of repeating units derived from methyl methacrylate and 0 to 50% by mass of repeating units derived from styrene.

32. A resin molded product comprising the methacrylic resin composition according to any one of claims 19 to 31.

33. A vehicle part comprising the resin molded article according to claim 32.

34. A toy comprising the resin molded article according to claim 32.

35. A signboard comprising the resin molded article according to claim 32.

36. A building material comprising the resin molded article according to claim 32.

37. A sanitary part comprising the resin molded article according to claim 32.

38. A cosmetic container comprising the resin molded article according to claim 32.

39. An optical member comprising the resin molded article according to claim 32.

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