Monomer composition, resin composition, method for producing resin composition, resin molded article, and method for producing resin molded article

Abstract

A monomer composition containing methyl methacrylate, an alpha-olefin, and at least one compound selected from the group consisting of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate, the total content of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate being more than 36 ppm by mass with respect to the total mass of the monomer composition, and the alpha-olefin being at least one compound selected from the group consisting of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate. The alpha-olefin includes at least one member selected from the group consisting of 2-ethyl-1-hexene, 1-octene, and 1-dodecene.

Description

Technical Field

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

[0002] Methacrylic resins have excellent transparency, heat resistance, and weather resistance, and have good balance in resin physical properties such as mechanical strength, thermal properties, and moldability. Due to such excellent characteristics, they are used for various applications such as vehicle parts, medical parts, toys, liquid containers, optical materials, billboards, displays, decorative parts, building parts, and electronic device panels, especially for parts with light transmissibility.

[0003] In the above applications, when a part using a methacrylic resin plate is set in an environment exposed to light such as direct sunlight or a UV lamp, there is a problem that the transparency of the methacrylic resin plate is significantly reduced. Therefore, there is a demand for a methacrylic resin that can maintain transparency even when exposed to light for a long time, that is, a methacrylic resin with excellent light stability.

[0004] As a technique for improving the light stability of methacrylic resins, for example, Patent Document 1 discloses a methacrylic resin obtained by polymerizing a monomer such as methyl methacrylate in the presence of a hindered amine compound having a specific structure, which is one of the light stabilizers. Patent Document 2 discloses a methacrylic resin containing a polymer having a triazine compound as a structural unit. Prior Art Documents Patent Documents

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 55-139404 Patent Document 2: Japanese Patent Application Laid-Open No. 2012-72333 Summary of the Invention Problems to be Solved by the Invention

[0006] However, the methacrylic resins described in Patent Documents 1 and 2 have improved light stability as the additives during polymerization increase. On the other hand, there is a problem of coloring caused by the additives. Therefore, there is a problem that it cannot be used when specific hue and transparency are required simultaneously.

[0007] In view of the above situation, an object of the present invention is to provide a monomer composition, a resin composition, a method for producing a resin composition, a resin molded article, and a method for producing a resin molded article for obtaining a resin composition that maintains the transparency and heat resistance inherent to methacrylic resins and has excellent light stability. Technical Solution for Solving the Problems

[0008] To solve the above problems, the present invention has the following features.

[0009] 〔1〕 A monomer composition, characterized by containing: methyl methacrylate, an α-olefin, and at least one compound selected from the group consisting of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate, The total content of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate is greater than 36 mass ppm with respect to the total mass of the monomer composition, The α-olefin contains at least one selected from the group consisting of 2-ethyl-1-hexene, 1-octene, and 1-dodecene. 〔2〕 The monomer composition according to 〔1〕, wherein the content of methyl methacrylate is 85 mass% or more with respect to the total mass of the monomer composition. 〔3〕 The monomer composition according to 〔1〕 or 〔2〕, wherein the content of methyl methacrylate is 90 mass% or more with respect to the total mass of the monomer composition. 〔4〕 The monomer composition according to any one of 〔1〕 to 〔3〕, wherein the content of the α-olefin is 0.1 mass ppm or more with respect to the total mass of the monomer composition. 〔5〕 The monomer composition according to any one of 〔1〕 to 〔4〕, wherein the content of the α-olefin is 10 mass ppm or more with respect to the total mass of the monomer composition. 〔6〕 The monomer composition according to any one of 〔1〕 to 〔5〕, wherein the content of the α-olefin is 60 mass ppm or more with respect to the total mass of the monomer composition. 〔7〕 The monomer composition according to any one of 〔1〕 to 〔6〕, wherein the content of the α-olefin is 80 mass ppm or more with respect to the total mass of the monomer composition. 〔8〕 The monomer composition according to any one of 〔1〕 to 〔7〕, wherein the content of at least one compound selected from the group consisting of a compound of a transition metal and a compound of a Group 13 element is 2×10 4 mass ppm or less with respect to the total mass of the α-olefin. 〔9〕 The monomer composition according to any one of [1] to [8], wherein the total content of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate is 40 mass ppm or more relative to the total mass of the monomer composition. 〔10〕 The monomer composition according to any one of [1] to [9], wherein the total content of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate is 60 mass ppm or more relative to the total mass of the monomer composition. 〔11〕 The monomer composition according to any one of [1] to

[10] , wherein the total content of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate is 70 mass ppm or more relative to the total mass of the monomer composition. 〔12〕 The monomer composition according to any one of [1] to

[11] , wherein the total content of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate is 100 mass ppm or more relative to the total mass of the monomer composition. 〔13〕 The monomer composition according to any one of [1] to

[12] , wherein the ratio of the content of the α-olefin to the total content of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate ([mass of the α-olefin] / [total mass of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate]) is 0.00001 or more and 1,000 or less. 〔14〕 The monomer composition according to any one of [1] to

[13] , which further contains an acrylate. 〔15〕 The monomer composition according to

[14] , wherein the acrylate is at least one compound selected from the group consisting of methyl acrylate, ethyl acrylate, and n-butyl acrylate. 〔16〕 The monomer composition according to

[14] , wherein the acrylate is methyl acrylate or ethyl acrylate. 〔17〕 The monomer composition according to any one of [1] to

[16] , which further contains styrene. 〔18〕 The monomer composition according to any one of [1] to

[17] , which further contains methyl isobutyrate. 〔19〕 A method for producing a resin composition, which includes a radical polymerization step of subjecting a polymerizable composition to radical polymerization, and the polymerizable composition contains the monomer composition according to any one of [1] to

[18] .

[20] A resin composition containing a polymer of the monomer composition described in any one of [1] to

[18] .[[-END]]

[21] A resin composition characterized by containing: a methacrylic polymer (P), an α-olefin, and at least one compound selected from the group consisting of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate. The total content of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate is greater than 26 mass ppm with respect to the total mass of the resin composition. The α-olefin contains at least one selected from the group consisting of 2-ethyl-1-hexene, 1-octene, and 1-dodecene.

[22] The resin composition according to

[21] , wherein the methacrylic polymer (P) contains 50 mass% or more of repeating units derived from methyl methacrylate with respect to the total mass of the methacrylic polymer (P).

[23] The resin composition according to

[21] or

[22] , wherein the methacrylic polymer (P) contains 70 mass% or more of repeating units derived from methyl methacrylate with respect to the total mass of the methacrylic polymer (P).

[24] The resin composition according to any one of

[21] to

[23] , wherein the content of the α-olefin is 0.1 mass ppm or more with respect to the total mass of the resin composition.

[25] The resin composition according to any one of

[21] to

[24] , wherein the content of the α-olefin is 10 mass ppm or more with respect to the total mass of the resin composition.

[26] The resin composition according to any one of

[21] to

[25] , wherein the content of the α-olefin is 60 mass ppm or more with respect to the total mass of the resin composition.

[27] The resin composition according to any one of

[21] to

[26] , wherein the content of the α-olefin is 80 mass ppm or more with respect to the total mass of the resin composition.

[28] The resin composition according to any one of

[21] to

[27] , wherein the total content of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate is 30 mass ppm or more with respect to the total mass of the resin composition.

[29] The resin composition according to any one of

[21] to

[28] , wherein the total content of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate is 40 mass ppm or more based on the total mass of the resin composition. 〔30〕 The resin composition according to any one of

[21] to

[29] , wherein the total content of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate is 60 mass ppm or more based on the total mass of the resin composition. 〔31〕 The resin composition according to any one of

[21] to

[30] , wherein the total content of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate is 80 mass ppm or more based on the total mass of the resin composition. 〔32〕 The resin composition according to any one of

[21] to

[31] , wherein the resin composition further contains methyl isobutyrate. 〔33〕 The resin composition according to any one of

[21] to

[32] , wherein the methacrylic polymer (P) contains repeating units derived from methyl methacrylate and repeating units derived from an acrylate. 〔34〕 The resin composition according to any one of

[21] to

[32] , wherein the methacrylic polymer (P) contains repeating units derived from methyl methacrylate and repeating units derived from styrene. 〔35〕 A resin molded article comprising the resin composition according to any one of

[20] to

[34] . 〔36〕 A vehicle component comprising the resin molded article according to

[35] . 〔37〕 A medical component comprising the resin molded article according to

[35] . 〔38〕 A toy comprising the resin molded article according to

[35] . 〔39〕 A liquid container comprising the resin molded article according to

[35] . 〔40〕 An optical material comprising the resin molded article according to

[35] . 〔41〕 A billboard comprising the resin molded article according to

[35] . 〔42〕 A display comprising the resin molded article according to

[35] . 〔43〕 A method for manufacturing a resin molded body, which includes a molding step of molding a resin composition containing a methacrylic polymer (P), an α-olefin, and at least one compound selected from the group consisting of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate. The total content of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate in the resin composition is greater than 26 mass ppm with respect to the total mass of the resin composition. The α-olefin includes at least one selected from the group consisting of 2-ethyl-1-hexene, 1-octene, and 1-dodecene. Advantages of the Invention

[0010] According to the present invention, it is possible to provide a monomer composition, a resin composition, a method for manufacturing a resin composition, a resin molded body, and a method for manufacturing a resin molded body for obtaining a resin composition that retains the transparency and heat resistance inherent in a methacrylic resin and has excellent light stability. Detailed Embodiments

[0011] The definitions of the following terms in this specification and the claims are as follows: "Monomer" refers to a compound having a polymerizable carbon-carbon double bond. "Repeating unit" refers to a unit derived from the monomer formed by polymerizing the monomer. The repeating unit may be a unit directly formed by a polymerization reaction or a unit formed by converting a part of the unit into another structure by treating the polymer. "(Meth)acrylate" refers to one or both of "acrylate" and "methacrylate". "(Meth)acryloyl" refers to one or both of "acryloyl" and "methacryloyl". "(Meth)acrylic acid" refers to one or both of "acrylic acid" and "methacrylic acid". "Conjugated" refers to the overlap of p orbitals across the σ bond present therebetween. "Non-conjugated" refers to the absence of conjugation. "Obtained resin composition" refers to a resin composition obtained by free-radical polymerization of a monomer mixture containing a monomer composition. "Obtained resin molded body" refers to a resin molded body obtained by molding a resin composition. "Mass %" represents the content ratio of a specified component contained in 100 mass % of the total amount. "Weight-average molecular weight" is a value measured by gel permeation chromatography using standard polystyrene as a standard sample. "UV" and "ultraviolet rays" refer to light mainly composed of light with a wavelength range of 295 to 430 nm.

[0012] "Transition metal" refers to the metallic elements in Groups 3 to 12 of the Periodic Table of Elements. Typically, they are scandium (Sc), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), yttrium (Y), zirconium (Zr), niobium (Nb), molybdenum (Mo), technetium (Tc), ruthenium (Ru), rhodium (Rh), palladium (Pd), silver (Ag), cadmium (Cd), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu), hafnium (Hf), tantalum (Ta), tungsten (W), rhenium (Re), osmium (Os), iridium (Ir), platinum (Pt), gold (Au), and mercury (Hg), etc. "Group 13 element" refers to the elements in Group 13 of the Periodic Table of Elements. Typically, they are boron (B), aluminum (Al), gallium (Ga), indium (In), and thallium (Tl). "Periodic Table of Elements" refers to "Periodic Table of Elements" (”Periodic Table ofElements”, [online], National Center for Biotechnology Information, [retrieved November 7, 2022], Internet, <URL: https: / / pubchem.ncbi.nlm.nih.gov / periodic-table / >).

[0013] In this specification, the numerical range represented by "~" means the range including the numerical values described before and after "~" as the lower limit value and the upper limit value. "A~B" means A or more and B or less.

[0014] <1. Monomer Composition> The monomer composition of the first embodiment of the present invention is characterized in that the monomer composition contains methyl methacrylate, an α-olefin, and at least one compound selected from the group consisting of propionic acid, methyl pyruvate, and methyl 2-methylbutyrate. The total content of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate is greater than 36 mass ppm with respect to the total mass of the monomer composition. The α-olefin contains at least one selected from the group consisting of 2-ethyl-1-hexene, 1-octene, and 1-dodecene (hereinafter, unless otherwise specified, "α-olefin" means at least one selected from the group consisting of 2-ethyl-1-hexene, 1-octene, and 1-dodecene). In addition, within the range that does not impair the effects of the present invention, other components may also be contained.

[0015] <1-1. Methyl methacrylate> The monomer composition of this embodiment contains methyl methacrylate. Methyl methacrylate can be produced, for example, by methods such as the acetone cyanohydrin method, the new acetone cyanohydrin method, the C4 direct oxidation method, the direct esterification method, the ethylene method, and the new ethylene method. In addition, methyl methacrylate obtained by thermally decomposing a resin composition obtained by polymerizing a monomer composition containing methyl methacrylate can also be used. Methyl methacrylate is more preferably methyl methacrylate obtained by thermally decomposing a resin composition obtained by polymerizing a monomer composition containing methyl methacrylate. By containing methyl methacrylate in the monomer composition of this embodiment, a resin composition having excellent light stability and the inherent heat resistance of the methacrylic resin can be provided.

[0016] The lower limit of the content of methyl methacrylate with respect to the total mass of the monomer composition is not particularly limited, and is preferably 85% by mass or more, more preferably 90% by mass or more, further preferably 95% by mass or more, and particularly preferably 97% by mass or more. In addition, the upper limit of the content of methyl methacrylate is not particularly limited, and is usually 99.99% by mass or less, and may also be 99.98% by mass or less or 99.97% by mass or less. Therefore, for example, ranges such as 85% by mass or more and 99.99% by mass or less, 90% by mass or more and 99.98% by mass or less, 95% by mass or more and 99.97% by mass or less, 97% by mass or more and 99.97% by mass or less, and 97% by mass or more and 99.97% by mass or less can be cited.

[0017] In addition, the total content of methyl methacrylate, an α-olefin, and at least one compound selected from the group consisting of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate with respect to the total mass of the monomer composition of this embodiment is not particularly limited, and is usually 100% by mass or less.

[0018] <1-2. α-olefin> The monomer composition of the present embodiment contains the following α-olefins, and the α-olefins include at least one selected from the group consisting of 2-ethyl-1-hexene, 1-octene, and 1-dodecene, and can provide a resin composition having excellent light stability. The α-olefins can be used alone or two or more thereof can be used in combination at any ratio.

[0019] The lower limit of the α-olefin content relative to the total mass of the monomer composition of the present embodiment is not particularly limited. From the viewpoint of providing a resin composition with good light stability, it is preferably 0.1 mass ppm or more, more preferably 10 mass ppm or more, further preferably 60 mass ppm or more, still more preferably 80 mass ppm or more, and particularly preferably 100 mass ppm or more.

[0020] The upper limit of the α-olefin content in the monomer composition of the present embodiment is not particularly limited. From the viewpoint of providing a resin composition that can maintain heat resistance well, it is preferably 10,000 mass ppm or less, more preferably 5,000 mass ppm or less, further preferably 4,000 mass ppm or less, still more preferably 3,000 mass ppm or less, and particularly preferably 2,000 mass ppm or less.

[0021] The above-mentioned preferred upper and lower limit values can be combined arbitrarily. Specifically, relative to the total mass of the monomer composition of the present embodiment, the content of the α-olefin is preferably 0.1 mass ppm or more and 10,000 mass ppm or less, more preferably 10 mass ppm or more and 5,000 mass ppm or less, further preferably 60 mass ppm or more and 4,000 mass ppm or less, still more preferably 80 mass ppm or more and 3,000 mass ppm or less, and particularly preferably 100 mass ppm or more and 2,000 mass ppm or less. It should be noted that when the monomer composition contains two or more α-olefins, the above content is the total content of the two or more α-olefins.

[0022] It is speculated that the coupling products of the α-olefins with free radicals generated by ultraviolet rays are stable to each other, and the free radical capture effect is excellent.

[0023] 2-Ethyl-1-hexene, 1-octene, and 1-dodecene do not volatilize due to heating during polymerization and are likely to remain in the resulting resin composition. Therefore, they can sufficiently contribute to improving the light stability of the resin composition obtained by polymerizing the monomer composition. At least one α-olefin selected from the group consisting of 2-ethyl-1-hexene, 1-octene, and 1-dodecene can easily exhibit the effect of improving light stability in a relatively small content. As described later, it is considered that the effect of improving light stability brought by α-olefins is related to the hydrogen bonded to the carbon adjacent to the double bond. Therefore, it is considered that even for the same mass, those with fewer carbon atoms have a larger number of carbon atoms participating in the double bond in one molecule of α-olefin, and thus are more likely to exhibit the effect of improving light stability.

[0024] As the α-olefin, among 2-ethyl-1-hexene, 1-octene, and 1-dodecene, more preferably one or more selected from 1-octene and 2-ethyl-1-hexene, and further preferably 1-octene in view of being likely to remain in the resin composition after polymerization. The ratio of 1-octene in the α-olefin is not particularly limited relative to the total mass of the α-olefin, preferably 50% by mass or more, more preferably 80% by mass or more, further preferably 90% by mass or more, and usually 100% by mass or less.

[0025] In the monomer composition of the present embodiment, the content of at least one compound selected from the group consisting of a compound of a transition metal and a compound of a Group 13 element is preferably 0 mass ppm or more and 2×10 4 mass ppm or less relative to the total mass of the α-olefin.

[0026] In the present embodiment, the α-olefin cannot obtain a resonance stabilization effect and has significantly lower reactivity compared to methyl methacrylate as a conjugated monomer. Therefore, as long as a specific polymerization catalyst such as at least one compound selected from the group consisting of a compound of a transition metal and a compound of a Group 13 element is used, and under non-special conditions where the catalyst effect is exerted, unreacted α-olefin (hereinafter also referred to as "α-olefin monomer") remains in the resulting resin composition. It is considered that a resin composition with good light stability can be provided by the remaining α-olefin monomer in the resin composition. That is, in order for the at least one compound not to exert the effect of a catalyst, the content of the at least one compound is preferably 2×10 4 mass ppm or less, more preferably 1×10 4 mass ppm or less, further preferably 1,000 mass ppm or less, particularly preferably 500 mass ppm or less, and particularly preferably not contained. Here, "not contained" means less than the detection limit.

[0027] As species of the above at least one compound, for example, there may be mentioned: compounds of transition metals of Group 5 to Group 11 having a chelating ligand or a Lewis acid catalyst. Specific examples of the transition metal include: vanadium, niobium, tantalum, chromium, molybdenum, tungsten, manganese, iron, platinum, ruthenium, cobalt, rhodium, nickel, palladium, and copper. Among these transition metals, preferably, they are transition metals of Group 8 to Group 11, more preferably, they are transition metals of Group 10, and further preferably, they are nickel (Ni) or palladium (Pd). These transition metals may be used alone or in combination of two or more.

[0028] The above chelating ligand has at least 2 atoms selected from the group consisting of P, N, O, and S, includes a ligand as bidentate or multidentate coordination, and is electronically neutral or anionic. The structure of the chelating ligand is exemplified in the general review by Ittel et al. (Ittel et al., “Late-Metal Catalysts for Ethylene Homo-and Copolymerization”, Chemical Reviews, March 25, 2000, Vol. 100, No. 4, pp. 1169-1204). As the chelating ligand, for example, there may be mentioned: bidentate anionic P, O ligands. As the bidentate anionic P, O ligands, for example, there may be mentioned: phosphonic acid, phosphonic carboxylic acid, phosphophenol, and phosphoenol. As chelating ligands other than the bidentate anionic P, O ligands, for example, there may be mentioned: bidentate anionic N, O ligands. As the bidentate anionic N, O ligands, for example, there may be mentioned: salicylaldimine and pyridinecarboxylic acid. As chelating ligands other than the bidentate anionic P, O ligands and the bidentate anionic N, O ligands, for example, there may be mentioned: diimine ligands, diphenoxide ligands, and diamide ligands.

[0029] Here, as the compound of transition metals of Group 5 to Group 11 having the above chelating ligand, that is, the catalyst, catalysts such as the so-called SHOP-type catalyst and Drent-type catalyst are typically known. The SHOP-type catalyst is a catalyst formed by coordination of a phosphorus-based ligand having an optionally substituted aryl group with nickel metal. In addition, the Drent-type catalyst is a catalyst formed by coordination of a phosphorus-based ligand having an optionally substituted aryl group with palladium metal.

[0030] In addition, as a representative Lewis acid catalyst, cationic complexes of divalent palladium or platinum can be cited. The cationic complexes of divalent palladium or platinum exhibit Lewis acidity and are useful as Lewis acid catalysts for Diels-Alder reactions and the like. In addition, compounds of group 13 elements boron and aluminum, titanium of the fourth-period transition metals, and zirconium of the fifth-period transition metals also exhibit Lewis acidity and are therefore preferred.

[0031] <1-3. At least one compound selected from the group consisting of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate> At least one compound selected from the group consisting of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate is one of the components contained in the monomer composition of the present embodiment. By making the total content of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate greater than 36 mass ppm with respect to the total mass of the monomer composition, a resin composition having excellent light stability can be provided. It should be noted that when the monomer composition contains two or more compounds selected from the group consisting of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate, the above content refers to the total content of these compounds. As a specific example, when only one of the three compounds is contained, it is sufficient that the content of one compound is greater than 36 mass ppm, and when all three compounds are contained, it is sufficient that the total content of the three compounds is greater than 36 mass ppm.

[0032] The lower limit of the total content of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate with respect to the total mass of the monomer composition of the present embodiment is not particularly limited, and is generally greater than 36 mass ppm, preferably 40 mass ppm or more, more preferably 60 mass ppm or more, further preferably 70 mass ppm or more, further more preferably 80 mass ppm or more, and particularly preferably 100 mass ppm or more, in order to provide a resin composition having good light stability.

[0033] The upper limit of the total content of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate with respect to the total mass of the monomer composition of the present embodiment is not particularly limited, and is preferably 20,000 mass ppm or less, more preferably 15,000 mass ppm or less, further preferably 10,000 mass ppm or less, further more preferably 6,000 mass ppm or less, and particularly preferably 5,000 mass ppm or less, in order to provide a resin composition that can maintain heat resistance well.

[0034] The above-mentioned preferred upper and lower limit values can be arbitrarily combined. Specifically, in the monomer composition of the present embodiment, the total content of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate is greater than 36 mass ppm and preferably 20,000 mass ppm or less, more preferably 40 mass ppm or more and 20,000 mass ppm or less, still more preferably 60 mass ppm or more and 15,000 mass ppm or less, even more preferably 70 mass ppm or more and 10,000 mass ppm or less, particularly preferably 80 mass ppm or more and 6,000 mass ppm or less, and most preferably 100 mass ppm or more and 5,000 mass ppm or less.

[0035] In the monomer composition of the present embodiment, the upper limit of the ratio of the content of α-olefin to the total content of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate (also referred to as "[mass of α-olefin] / [total mass of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate] ratio") is not particularly limited. From the perspective of being able to provide a resin molded article with good light stability through the interaction between at least one compound selected from the group consisting of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate and α-olefin, it is preferably 1,000 or less, more preferably 500 or less, still more preferably 300 or less, even more preferably 100 or less, particularly preferably 10 or less. The lower limit of the [mass of α-olefin] / [total mass of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate] ratio is not particularly limited. From the perspective of improving the heat resistance of the resin molded article, it is preferably 0.00001 or more, more preferably 0.0001 or more, still more preferably 0.001 or more, even more preferably 0.01 or more, particularly preferably 0.5 or more.

[0036] The above upper limit value and lower limit value can be arbitrarily combined. For example, as the preferred range of the [mass of α-olefin] / [total mass of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate] ratio, the ranges of 0.00001 or more and 1,000 or less, 0.0001 or more and 500 or less, 0.001 or more and 300 or less, 0.01 or more and 100 or less, and 0.5 or more and 10 or less can be cited. Among these, the [mass of α-olefin] / [total mass of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate] ratio is more preferably 0.0001 or more and 500 or less, and still more preferably 0.001 or more and 300 or less.

[0037] <1-4. Monomers other than methyl methacrylate> The monomer composition of this embodiment may also contain monomers other than methyl methacrylate. It should be noted that in this specification, "monomer" refers to an unpolymerized compound. As monomers other than methyl methacrylate, for example, the monomers shown in the following (1) to (16) can be cited. The monomers shown in the following (1) to (16) can be used alone or in combination of two or more in any ratio. (1) Methacrylate: For example, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, 2-ethylhexyl methacrylate, phenyl methacrylate or benzyl methacrylate. (2) Acrylate: For example, methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, tert-butyl acrylate or 2-ethylhexyl acrylate. (3) Unsaturated carboxylic acid: For example, acrylic acid, methacrylic acid, maleic acid or itaconic acid. (4) Unsaturated carboxylic anhydride: For example, maleic anhydride or itaconic anhydride. (5) Maleimide: For example, N-phenylmaleimide or N-cyclohexylmaleimide. (6) Hydroxyl-containing vinyl monomer: 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 monomer: For example, methacrylamide or acrylonitrile. (10) Epoxy group-containing monomer: For example, glycidyl acrylate or glycidyl methacrylate. (11) Aromatic vinyl monomer: For example, styrene or α-methylstyrene. (12) Alkanediol di(meth)acrylate: For example, ethylene glycol di(meth)acrylate, 1,2-propanediol di(meth)acrylate, 1,3-butanediol di(meth)acrylate, neopentyl 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, or polyethylene glycol di(meth)acrylate. (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 containing an ethylenically unsaturated polycarboxylic acid and at least one diol. (16) Vinyl ester prepolymers obtained by acrylate-modifying the terminals of epoxy groups.

[0038] Among these, from the viewpoint of providing a resin composition having an excellent balance of transparency, heat resistance, and moldability, the monomer is preferably at least one acrylate selected from the group consisting of methyl acrylate, ethyl acrylate, and n-butyl acrylate, more preferably methyl acrylate or ethyl acrylate. Further, relative to the total mass of the monomer composition, the content of the acrylate is preferably 0% by mass or more and 30% by mass or less. By containing an acrylate in the monomer composition, a resin composition having excellent light stability can be provided. In addition, a decrease in light stability when a resin molded body containing the resin composition is exposed to light for a long time can be suppressed. Further, by changing the acrylate to styrene, it can also be applied to the production of a methacrylic polymer (P1) containing repeating units derived from methyl methacrylate (hereinafter also referred to as "methyl methacrylate units") and repeating units derived from styrene (hereinafter also referred to as "styrene units"). At this time, the content of styrene can also be applied to the content ratio of the styrene units described in <3-2. Methacrylic polymer (P)>.

[0039] <1-5. Methyl isobutyrate> The monomer composition preferably further contains methyl isobutyrate. By containing this compound, a resin composition having further excellent light stability can be provided. The reason is presumed as follows: By containing the α-olefin described in <3-1. Effects> and a specific amount of at least one compound selected from the group consisting of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate, the effect of improving light stability is further enhanced. In addition, a decrease in light stability when a resin molded body containing the resin composition is exposed to light for a long time can be suppressed.

[0040] When the monomer composition of the present embodiment contains methyl isobutyrate, the total content of methyl isobutyrate, methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate is preferably an amount within the range of the total content of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate described above.

[0041] In addition, when the monomer composition of the present embodiment contains methyl isobutyrate, the content of methyl isobutyrate is preferably 10 mass ppm or more, more preferably 50 mass ppm or more, still more preferably 100 mass ppm or more, particularly preferably 200 mass ppm or more, most preferably 250 mass ppm or more, and preferably 10,000 mass ppm or less, more preferably 8,000 mass ppm or less, still more preferably 5,000 mass ppm or less, particularly preferably 3,000 mass ppm or more, most preferably 1,500 mass ppm or more, based on the total mass of the monomer composition.

[0042] The above-mentioned preferred upper and lower limit values can be arbitrarily combined. Specifically, as the preferred range of the content of methyl isobutyrate based on the total mass of the monomer composition of the present embodiment, there can be mentioned ranges of 10 mass ppm or more and 10,000 mass ppm or less, 50 mass ppm or more and 8,000 mass ppm or less, 100 mass ppm or more and 5,000 mass ppm or less, 200 mass ppm or more and 3,000 mass ppm or less, and 250 mass ppm or more and 1,500 mass ppm or less.

[0043] <1-6. Additives> The monomer composition of the present embodiment may also contain other additives. Examples of the additives include known additives such as a mold release agent, a heat stabilizer, a flow aid, a plasticizer, an antioxidant, an antistatic agent, a light stabilizer (excluding α-olefins, methyl isobutyrate, methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate), an ultraviolet absorber, a flame retardant, a flame retardant aid, a filler, a pigment, a dye, a silane coupling agent, a leveling agent, an antifoaming agent, and a fluorescent agent. These additives can be used alone or in combination of any two or more in any ratio.

[0044] In the present embodiment, it is considered that α-olefins and at least one compound selected from the group consisting of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate exhibit excellent light stability through an action mechanism different from that of commonly known UV absorbers and radical scavengers (HALS). Therefore, α-olefins and at least one compound selected from the group consisting of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate can also be used in combination with additives such as UV absorbers and HALS. By the monomer composition containing α-olefins, at least one compound selected from the group consisting of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate, and the additive, a resin composition and a resin molded body having further increased light stability can be provided.

[0045] In addition, the monomer composition of the present embodiment may contain compounds such as methacrolein and methanol that are inevitably mixed into methyl methacrylate.

[0046] <2. Polymerizable composition> The polymerizable composition of the second embodiment of the present invention is a form of raw material for obtaining the resin composition of the third embodiment of the present invention described later. The polymerizable composition of the present embodiment (also referred to as "polymerizable composition (X2)") is a polymerizable composition containing the monomer composition and a radical polymerization initiator known as needed.

[0047] <2-1. Radical polymerization initiator> Examples of the radical polymerization initiator include: known azo compounds such as 2,2'-azobis(isobutyronitrile) and 2,2'-azobis(2,4-dimethylvaleronitrile); known organic peroxides such as benzoyl peroxide and lauroyl peroxide; and the like. They can be used alone or in combination of two or more in any ratio. In addition, known polymerization accelerators such as amines and thiols can be used in combination with the radical polymerization initiator as needed.

[0048] The content of the radical polymerization initiator in the polymerizable composition (X2) is not particularly limited, and those skilled in the art can appropriately determine it according to known techniques. Specifically, with respect to 100 parts by mass of the total mass of the polymerizable composition (X2), the content of the radical polymerization agent can be 0.005 parts by mass or more and 5 parts by mass or less, or can be 0.01 parts by mass or more and 1.0 part by mass or less.

[0049] <2-2. Additive> The form of the additive is the same as that described in <1-6. Additive>. It should be noted that the additive can be one kind or two or more kinds.

[0050] <3. Resin composition> The resin composition of the third embodiment of the present invention (hereinafter also simply referred to as "resin composition") is a resin composition containing at least a methacrylic polymer (P), an α-olefin, and at least one compound selected from the group consisting of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate. Among them, relative to the total mass of the resin composition, the total content of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate is greater than 26 mass ppm, and the α-olefin contains at least one selected from the group consisting of 2-ethyl-1-hexene, 1-octene, and 1-dodecene. It should be noted that when the resin composition contains two or more compounds selected from the group consisting of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate, the above content refers to the total content of these compounds. As a specific example, when only one of the three compounds is contained, it is sufficient that the content of one compound is greater than 26 mass ppm, and when all three compounds are contained, it is sufficient that the total content of the three compounds is greater than 26 mass ppm. The resin composition of this embodiment may be a composition of a polymer containing the monomer composition of the first embodiment of the present invention, or a composition obtained by subjecting the polymerizable composition of the second embodiment of the present invention to radical polymerization.

[0051] By containing the methacrylic polymer (P), the resin composition of this embodiment can provide a resin molded body having excellent heat resistance and good transparency. In the resin composition containing the methacrylic polymer (P), by containing an α-olefin and at least one compound selected from the group consisting of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate in a specific content, the following resin molded body can be provided. In the polymerization chain of the methacrylic polymer (P), the α-olefin and at least one compound selected from the group consisting of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate exist in a monomer state, and even when exposed to UV for a long time, yellowing can be suppressed, and further reduction of light stability can be suppressed. In addition, the form of the resin composition is not particularly limited, and it is usually solid. The form of at least one compound selected from the group consisting of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate is the same as that described in <1-3. At least one compound selected from the group consisting of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate>. The form of the α-olefin is the same as that described in <1-2. α-olefin>.

[0052] The content of the methacrylic polymer (P) is not particularly limited with respect to the total mass of the resin composition. From the viewpoint of improving heat resistance, it is usually 80.0% by mass or more, preferably 85.0% by mass or more, more preferably 90.0% by mass or more, further preferably 95.0% by mass or more, and particularly preferably 99.0% by mass or more. On the other hand, from the viewpoint of obtaining excellent light stability, the content is usually 99.99% by mass or less, preferably 99.9785% by mass or less, more preferably 99.97% by mass or less, further preferably 99.95% by mass or less, and particularly preferably 99.90% by mass or less. The above upper and lower limits can be arbitrarily combined. For example, as the preferred content of the methacrylic polymer (P), the ranges of 80.0% by mass or more and 99.99% by mass or less, 85.0% by mass or more and 99.9785% by mass or less, 90.0% by mass or more and 99.97% by mass or less, 95.0% by mass or more and 99.95% by mass or less, and 99.0% by mass or more and 99.90% by mass or less can be cited. It should be noted that when the resin composition contains two or more methacrylic polymers (P), the above content is the total content of the two or more methacrylic polymers (P).

[0053] The content of the α-olefin is not particularly limited with respect to the total mass of the resin composition. From the viewpoint of obtaining excellent light stability, it is usually 0.1 mass ppm or more, preferably 10 mass ppm or more, more preferably 60 mass ppm or more, further preferably 80 mass ppm or more, and particularly preferably 100 mass ppm or more.

[0054] The upper limit of the α-olefin content is not particularly limited with respect to the total mass of the resin composition of the present embodiment. From the viewpoint of improving the heat resistance of the resin molded body, it is usually 10,000 mass ppm or less, preferably 5,000 mass ppm or less, more preferably 4,000 mass ppm or less, further preferably 3,000 mass ppm or less, and particularly preferably 2,000 mass ppm or less.

[0055] The above upper limit value and lower limit value can be arbitrarily combined. For example, with respect to the total mass of the resin composition, as the preferred content of the α-olefin, the following ranges can be cited: 0.1 mass ppm or more and 10,000 mass ppm or less, 10 mass ppm or more and 5,000 mass ppm or less, 60 mass ppm or more and 4,000 mass ppm or less, 80 mass ppm or more and 3,000 mass ppm or less, and 100 mass ppm or more and 2,000 mass ppm or less. Among these, the content of the α-olefin is more preferably 10 mass ppm or more and 5,000 mass ppm or less, and further preferably 100 mass ppm or more and 2,000 mass ppm or less.

[0056] With respect to the total mass of the resin composition of the present embodiment, the total content of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate is usually 26 mass ppm or more, preferably 30 mass ppm or more, more preferably 40 mass ppm or more, further preferably 60 mass ppm or more, particularly preferably 80 mass ppm or more, and most preferably 100 mass ppm or more, from the viewpoint of obtaining excellent light stability.

[0057] With respect to the total mass of the resin composition of the present embodiment, the upper limit of the total content of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate is not particularly limited. From the viewpoint of improving the heat resistance of the resin molded body, it is preferably 20,000 mass ppm or less, more preferably 15,000 mass ppm or less, further preferably 10,000 mass ppm or less, particularly preferably 5,000 mass ppm or less, and most preferably 3,000 mass ppm or less.

[0058] The above upper limit value and lower limit value can be arbitrarily combined. For example, as the total content of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate, the following ranges can be cited: more than 26 mass ppm and 20,000 mass ppm or less, 30 mass ppm or more and 20,000 mass ppm or less, 40 mass ppm or more and 15,000 mass ppm or less, 60 mass ppm or more and 10,000 mass ppm or less, 80 mass ppm or more and 5,000 mass ppm or less, and 100 mass ppm or more and 3,000 mass ppm or less. Among these, the total content of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate is more preferably 30 mass ppm or more and 20,000 mass ppm or less, and further preferably 40 mass ppm or more and 15,000 mass ppm or less.

[0059] <3-1. Effects> The monomer composition of the first embodiment of the present invention contains methyl methacrylate, an α-olefin, and at least one compound selected from the group consisting of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate. The resin composition obtained by subjecting the polymerizable composition (X2) containing the monomer composition to radical polymerization has excellent light stability and suppressed yellowing while ensuring excellent heat resistance. It is presumed that the resin composition having excellent light stability and suppressed yellowing while ensuring excellent heat resistance is obtained because the monomer composition of the first embodiment of the present invention contains a specific α-olefin and at least one compound selected from the group consisting of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate in a specific content, as follows.

[0060] The main chain or side chain of a polymer containing units based on methyl methacrylate (methacrylic polymer) is cleaved by light to generate radical species. Moreover, generally, the generated radical species cause yellowing of the methacrylic resin and a decrease in mechanical strength due to a decrease in molecular weight.

[0061] However, the α-olefin and at least one compound selected from the group consisting of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate contained in the monomer composition of the first embodiment of the present invention have a significantly lower reactivity compared to methyl methacrylate as a conjugated monomer and cannot obtain a resonance stabilization effect. Therefore, unless under special conditions, in the obtained resin composition, unreacted α-olefin (also referred to as α-olefin monomer) and at least one compound selected from the group consisting of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate (also referred to as at least one compound monomer selected from the group consisting of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate) remain. Moreover, it is considered that the unreacted α-olefin and at least one compound selected from the group consisting of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate act as radical scavengers to supplement the radical species. Thus, the hydrogen atom bonded to the carbon atom adjacent to the double bond site of the unreacted α-olefin is abstracted to supplement the radical species.

[0062] At this time, it is considered that the unreacted α-olefin from which a hydrogen atom has been abstracted interacts with at least one compound selected from the group consisting of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate to substitute the hydrogen atom, so that the α-olefin functions as a radical scavenger again. Therefore, it can be considered that not only the effect of improving the light stability of the resin composition obtained by each of the α-olefin and at least one compound selected from the group consisting of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate alone, but also the synergistic effect obtained by using the α-olefin and at least one compound selected from the group consisting of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate in combination, so that the light stability of the obtained resin composition shows significantly good light stability.

[0063] In the resin composition of the present embodiment, the upper limit of the ratio of the content of the α-olefin to the total content of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate (also referred to as "[mass of α-olefin] / [total mass of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate] ratio") is not particularly limited. From the viewpoint of improving the light stability of the resin molded article, it is preferably 1,000 or less, more preferably 500 or less, further preferably 300 or less, still further preferably 100 or less, and particularly preferably 10 or less due to the interaction between at least one compound selected from the group consisting of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate and the α-olefin. The lower limit of the [mass of α-olefin] / [total mass of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate] ratio is not particularly limited. From the viewpoint of improving the heat resistance of the resin molded article, it is preferably 0.00001 or more, more preferably 0.0001 or more, further preferably 0.001 or more, still further preferably 0.01 or more, and particularly preferably 0.5 or more.

[0064] The above upper limit value and lower limit value can be arbitrarily combined. For example, as the preferred range of the [mass of α-olefin] / [total mass of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate] ratio, there can be mentioned ranges of 0.00001 or more and 1,000 or less, 0.0001 or more and 500 or less, 0.001 or more and 300 or less, 0.01 or more and 100 or less, and 0.5 or more and 10 or less. Among these, the [mass of α-olefin] / [total mass of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate] ratio is more preferably 0.0001 or more and 500 or less, and further preferably 0.001 or more and 300 or less.

[0065] <3-2.Methacrylic polymer (P)> The methacrylic polymer (P) is one of the components contained in the resin composition of the present embodiment. The resin composition contains a methacrylic polymer (P), and can improve transparency while suppressing decomposition caused by heat or light, making the heat formability, heat resistance, and mechanical strength good. Further, due to the heat resistance originally possessed by the methacrylic polymer (P) and the synergistic effect of an α-olefin and at least one compound selected from the group consisting of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate in a specific content, a methacrylic resin molded article with high light stability and retained heat resistance can be obtained for the resulting resin composition.

[0066] The content ratio of methyl methacrylate units in the methacrylic polymer (P) is not particularly limited with respect to the total mass of the methacrylic polymer (P). From the perspective of good heat resistance, it is preferably 50% by mass or more, more preferably 60% by mass or more, further preferably 70% by mass or more, further more preferably 80% by mass or more, particularly preferably 90% by mass or more, and usually 100% by mass or less.

[0067] The methacrylic polymer (P) is preferably a copolymer methacrylic polymer (P1) containing methyl methacrylate units and repeating units derived from an acrylate (hereinafter also referred to as "acrylate units") or styrene units as needed. The arrangement of these copolymers is not particularly limited. For example, it can be a random copolymer, a block copolymer, an alternating copolymer, etc., and a random copolymer is preferred.

[0068] As the above repeating units derived from an acrylate, they are repeating units derived from an acrylate having an alkyl group with 1 to 6 carbon atoms in the side chain. As the monomer constituting this unit, as long as it is a monomer capable of copolymerizing with methyl methacrylate, there is no particular limitation. For example, acrylates such as methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, or tert-butyl acrylate can be cited. They can be used alone or in combination of two or more in any ratio. Among these monomers, from the perspective of ensuring high light stability, the resin molded article containing the resin composition is preferably at least one acrylate selected from the group consisting of methyl acrylate, ethyl acrylate, and n-butyl acrylate, and more preferably methyl acrylate and ethyl acrylate.

[0069] The content ratio of methyl methacrylate units in the methacrylic polymer (P1) is not particularly limited with respect to the total mass of the methacrylic polymer (P1). From the perspective of good heat resistance, it is preferably 50% by mass or more, more preferably 60% by mass or more, further preferably 70% by mass or more, further preferably 80% by mass or more, particularly preferably 90% by mass or more, and usually 100% by mass or less.

[0070] The content ratio of acrylate units in the methacrylic acid-based polymer (P1) is not particularly limited. From the perspective of improving heat resistance and light stability, it is preferably 50% by mass or less, more preferably 30% by mass or less, further preferably 20% by mass or less, particularly preferably 10% by mass or less, and usually 0% by mass or more. It should be noted that when the methacrylic acid-based polymer (P1) contains two or more types of acrylate units, the above content ratio is the total content ratio of the two or more types of acrylate units.

[0071] The content ratio of styrene units in the methacrylic acid-based polymer (P1) is not particularly limited. From the perspective of improving transparency, it is preferably 50% by mass or less, more preferably 40% by mass or less, further preferably 30% by mass or less, still further preferably 20% by mass or less, particularly preferably 10% by mass or less, and usually 0% by mass or more.

[0072] Furthermore, within the range of achieving the inventive effect, the methacrylic acid-based polymer (P) in the present embodiment may contain structural units derived from a polyfunctional monomer having two or more radically polymerizable functional groups in one molecule (hereinafter referred to as "polyfunctional monomer units"). The radically polymerizable functional group mentioned here refers to any group having a carbon-carbon double bond and capable of radical polymerization. Specifically, examples include vinyl, allyl, (meth)acryloyl, (meth)acryloyloxy, etc. In particular, (meth)acryloyl is preferred from the perspective of excellent storage stability of compounds having a radically polymerizable functional group and easy control of the polymerizability of the compound. It should be noted that the respective radically polymerizable functional groups in a monomer having two radically polymerizable functional groups may be the same or different. By including polyfunctional monomer units, the methacrylic acid-based polymer (P) can improve solvent resistance, chemical resistance, etc.

[0073] Examples of polyfunctional monomers include allyl methacrylate, allyl acrylate, ethylene glycol di(meth)acrylate, ethylene glycol tri(meth)acrylate, neopentyl glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, etc., but are not particularly limited to these. They can be used alone or in combination of two or more in any ratio. Among these, from the perspective of better solvent resistance and chemical resistance, the polyfunctional monomer is more preferably selected from ethylene glycol di(meth)acrylate and neopentyl glycol di(meth)acrylate, and further preferably ethylene glycol di(meth)acrylate.

[0074] Furthermore, in the resin composition of the present embodiment, the weight average molecular weight (Mw) of the above-mentioned methacrylic polymer (P) measured by gel permeation chromatography (GPC) is not particularly limited. The weight average molecular weight (Mw) can be appropriately set according to the use of the resin molded body and the like. For example, it can be 10,000 or more, it can be 100,000 or more, it can be 150,000 or more, and it can be 1,000,000 or less, it can be 2,000,000 or less, and it can also be 4,000,000 or less. By appropriately increasing the weight average molecular weight, the solvent resistance and chemical resistance can be improved.

[0075] The weight average molecular weight (Mw) of the methacrylic polymer (P) can be controlled by adjusting the polymerization temperature, polymerization time, addition amount of the polymerization initiator, or the type and addition amount of the chain transfer agent, etc.

[0076] <3-Methyl isobutyrate> The above resin composition preferably further contains methyl isobutyrate. By containing this compound, a resin composition with further excellent light stability can be provided. The speculation is as follows: By containing the α-olefin described in <3-1. Effect> and at least one compound selected from the group consisting of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate in a specific amount, the effect of improving light stability is further enhanced. In addition, it is possible to suppress the decrease in light stability when the resin molded body containing the resin composition is exposed to light for a long time.

[0077] When the resin composition of the present embodiment contains methyl isobutyrate, the total content of methyl isobutyrate, methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate is preferably an amount within the range of the total content of the above-mentioned methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate with respect to the total mass of the resin composition.

[0078] In addition, when the resin composition of the present embodiment contains methyl isobutyrate, the content of methyl isobutyrate is preferably 5 mass ppm or more, more preferably 10 mass ppm or more, further preferably 15 mass ppm or more, particularly preferably 30 mass ppm or more, most preferably 40 mass ppm or more, and preferably 20,000 mass ppm or less, more preferably 5,000 mass ppm or less, further preferably 1,000 mass ppm or less, particularly preferably 500 mass ppm or more, most preferably 100 mass ppm or more.

[0079] The above-mentioned preferred upper and lower limit values can be combined arbitrarily. Specifically, with respect to the total mass of the resin composition of the present embodiment, the preferred range of the content of methyl isobutyrate may be: 5 mass ppm or more and 20,000 mass ppm or less, 10 mass ppm or more and 5,000 mass ppm or less, 15 mass ppm or more and 1,000 mass ppm or less, 30 mass ppm or more and 500 mass ppm or less, and 40 mass ppm or more and 100 mass ppm or less.

[0080] <3-4. Properties of the resin composition> The resin composition of the present embodiment contains the above-mentioned methacrylic polymer (P), an α-olefin, and a specific amount of at least one compound selected from the group consisting of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate, and thus has excellent light stability.

[0081] Specifically, when a test piece (a square shape with a length of 50 mm × a width of 50 mm and a thickness of 3 mm) composed of the resin composition is subjected to the UV exposure test shown below, for the above-mentioned test piece, the yellowness index (YI) measured according to ASTM D1925 between before the start of the UV exposure test and 200 hours after the start of the UV exposure test is 6.2 or less, preferably 6.0 or less, more preferably 5.8 or less, further preferably 5.5 or less, further more preferably 5.0 or less, and particularly preferably 4.8 or less.

[0082] <4. Resin molded article> The resin molded article of the fourth embodiment of the present invention (also simply referred to as "resin molded article") is a resin molded article containing the resin composition of the third embodiment of the present invention. That is, the resin molded article of the present embodiment contains the resin composition of the third embodiment of the present invention. By passing through a molding process of molding the resin composition, the following resin molded article can be obtained, which retains the transparency and heat resistance inherent in the methacrylic resin and has excellent light stability. Examples of the molding method in the molding process include: compression molding, injection molding, gas-assisted injection molding, melt deposition molding, extrusion molding, blow molding, film molding, hollow molding, multilayer molding, melt spinning, etc. In the present specification, the resin molded article is not particularly limited as long as it is a molded article containing the above-mentioned resin composition, and a molded article composed only of the resin composition substantially belongs to either the resin composition or the resin molded article.

[0083] The shape of the above resin molded body is not limited to the following. For example, granular pellets, plate-shaped resin molded bodies (resin plates), and sheet- or film-shaped resin molded bodies (resin sheets) can be cited. As the thickness of the resin molded body, it can be adjusted to any thickness according to needs from thick plate shape to thin film shape. For example, it can be set to a thickness of 0.1 μm or more and 30 mm or less, or 1 mm or more and 30 mm or less.

[0084] Since the resin molded body contains the above resin composition, it has excellent light stability. That is, the resin molded body exhibits the following excellent light stability: the yellow index (YI) measured according to ASTM D1925 between before the start of the UV exposure test and 200 hours after the start of the UV exposure test is 6.0 or less, preferably 5.5 or less, more preferably 5.0 or less, further preferably 4.5 or less, and particularly preferably 4.0 or less.

[0085] <5. Manufacturing method of resin composition or resin molded body> The method for manufacturing a resin composition or a resin molded body containing the resin composition (hereinafter, the resin composition and the resin molded body are collectively referred to as "resin composition, etc.") is not particularly limited. As a specific manufacturing method of the resin composition, etc., for example, a method including the following radical polymerization step can be cited, and the radical polymerization step is to subject the polymerizable composition (X2) of the second embodiment of the present invention, preferably the polymerizable composition (X2) containing the monomer composition of the first embodiment of the present invention, to radical polymerization. The radical polymerization step may also include the following steps: a slurry preparation step of polymerizing a part of the polymerizable composition (X2) to prepare a slurry, and a polymerization step of polymerizing the polymerizable components in the slurry. It should be noted that "polymerizing a part of the polymerizable composition (X2)" in the slurry preparation step means polymerizing in such a way that the content of the methacrylic acid-based polymer in the obtained slurry is 10% by mass or more and 80% by mass or less, preferably 10% by mass or more and 60% by mass or less, more preferably 10% by mass or more and 40% by mass or less.

[0086] When polymerizing the polymerizable composition (X2), the polymerization temperature is not particularly limited, and those skilled in the art can appropriately determine it according to known techniques. Generally, according to the type of the radical polymerization initiator used, it is preferably set appropriately in the range of 40°C or more and 180°C or less, more preferably 50°C or more and 150°C or less. In addition, the polymerizable composition (X2) can be polymerized under multi-stage temperature conditions as needed. The polymerization time can be appropriately determined according to the progress of polymerization and curing.

[0087] As a polymerization method of the polymerizable composition (X2), for example, bulk polymerization method, suspension polymerization method, emulsion polymerization method, dispersion polymerization method, etc. can be cited. Among these, from the viewpoint of productivity, the bulk polymerization method is preferred.

[0088] In addition, specific examples of the method for producing a resin composition or the like include the following methods: using a known casting polymerization method such as a cell-cast method or a continuous casting method, a method of obtaining a resin composition or the like by a bulk polymerization method, or a method of obtaining a resin composition or the like by shaping a composition produced by a bulk polymerization method. From the viewpoint of being able to further improve the heat resistance of the resin composition by high molecular weightization and introduction of a crosslinked structure, a method using a casting polymerization (injection molding polymerization) method is more preferred.

[0089] As a casting polymerization method, for example, a cell-cast method can be cited. In the case of obtaining a resin composition or the like having a plate-like form, a space formed by two opposed glass plates or metal plates (SUS plates) and a gasket such as a soft resin tube disposed at its edge is used as a mold, and the polymerizable composition (X2) or a slurry obtained by polymerizing a part of the polymerizable composition (X2) is injected into the mold, and polymerization is completed by performing a heat polymerization treatment, and the resin composition or the like is taken out from the mold. Alternatively, a continuous casting method can be cited, which uses a space formed by two stainless steel endless belts traveling relatively in the same direction at the same speed with a predetermined interval therebetween and gaskets such as soft resin tubes disposed on both side edges thereof as a mold, and the polymerizable composition (X2) or a slurry obtained by polymerizing a part of the polymerizable composition (X2) is continuously injected into the mold from one end of the endless belt, and polymerization is completed by performing a heat polymerization treatment, and the resin composition or the like is continuously taken out from the other end of the endless belt. By appropriately adjusting the gap interval of the mold by the thickness (diameter) of the gasket, a resin composition or the like having a desired thickness can be obtained. The thickness of the plate-like resin composition or the like is usually set in the range of 1 mm or more and 30 mm or less.

[0090] <6. Use> The uses of the above-mentioned resin composition and resin molded body (“resin composition or the like”) are not particularly limited, and it is preferably used as a light-transmissive component, particularly a transparent component, used in any of vehicle components, medical components, toys, liquid containers, optical materials, billboards, displays, decorative components, building components, and electronic device panels. Examples

[0091] Hereinafter, examples and reference examples are given to more specifically illustrate the features of the present invention. The materials, amounts used, ratios, treatment contents, treatment operation steps, etc. shown in the following examples can be appropriately changed as long as they do not depart from the gist of the present invention. Therefore, the scope of the present invention is not limited to the specific examples shown below. In addition, "parts" hereinafter means "parts by mass".

[0092] The abbreviations and names of the compounds used in the examples and reference examples are as follows: · Methyl methacrylate: Methyl methacrylate (manufactured by Mitsubishi Chemical Corporation) · Methyl pyruvate (manufactured by Tokyo Chemical Industry Co., Ltd.) · Methyl 2-methylbutyrate (manufactured by Tokyo Chemical Industry Co., Ltd.) · Methyl propionate (manufactured by Tokyo Chemical Industry Co., Ltd.) · 1-Octene (manufactured by Tokyo Chemical Industry Co., Ltd.) · 2-Ethyl-1-hexene (manufactured by Tokyo Chemical Industry Co., Ltd.) It should be noted that in methyl methacrylate (manufactured by Mitsubishi Chemical Corporation), relative to the total mass of methyl methacrylate, it contains 260 mass ppm of methyl isobutyrate, 8 mass ppm of methyl propionate, 19 mass ppm of methyl pyruvate, and 8 mass ppm of methyl 2-methylbutyrate.

[0093] [Measurement method and evaluation method] <Measurement method for the content of at least one compound selected from the group consisting of compounds of transition metals and compounds of Group 13 elements in the monomer composition> Precisely weigh 2 g of the monomer composition and place it in a Kjeldahl digestion flask. Add 3 mL of sulfuric acid, completely carbonize it in a Kjeldahl digestion apparatus, and then cool it. Add 2 mL of sulfuric acid to it, heat and cool, add 3 mL of nitric acid for re-decomposition, and repeat this series of operations 3 times. After cooling, add 3 mL of nitric acid and 1 mL of hydrogen peroxide, heat and then cool again, and repeat this operation until there is no coloring. After heating and volatilizing the nitric acid and hydrogen peroxide in the Kjeldahl flask, add sulfuric acid so that the sulfuric acid content in the Kjeldahl flask is 5 mL to prepare a solution. Transfer the entire amount of this solution to a 100 mL volumetric flask and dilute it with ultrapure water. Quantitative analysis of each element in this solution was carried out with an ICP emission spectroscopic analysis apparatus under the following conditions.

[0094] Apparatus used: ICP emission spectroscopic analysis apparatus (manufactured by PerkinElmer, model name: Optima8300) Output power: 1300 W Pump speed: 1.0 mL / minute Plasma gas flow rate: 10 L / min Auxiliary gas flow rate: 0.2 L / min Atomizing gas flow rate: 0.55 L / min Detector: SCD (Split array type CCD) Integration time: Automatic (1 - 5 seconds) Number of measurements: 3 times Measurement method: Absolute calibration curve method Observation direction: Axial

[0095] <Method for determining the residual amount of the target substance in the resin composition> (1) Operating steps for sample and test solution preparation The resin molded bodies obtained in the examples and reference examples were finely pulverized, and 0.2 g of the pulverized resin was dissolved in 10 mL of acetone for residual pesticide test (hereinafter only referred to as "acetone"). After the resin was dissolved, 1 mL of the internal standard solution was added using a single - mark pipette. The internal standard solution used a 0.1% by volume methyl salicylate / acetone solution. Three test solutions with different concentrations were prepared by diluting the target standard reagent with acetone. By performing gas chromatography - mass spectrometry (GC / MS) measurement described below, a three - point calibration curve was made to quantify the content of each target substance in the sample. The internal standard solution used a 0.1% by volume methyl salicylate / acetone solution.

[0096] (GC / MS measurement conditions) Apparatus: GC HP6890 / MS HP5973 (manufactured by Agilent Technologies) Ionization method: EI (Electron Ionization) method Chromatographic column: DB - WAX 60 m × 250 μm × 0.5 μm (manufactured by Agilent Technologies) Temperature rising conditions: 70°C (5 minutes) → 200°C (5 minutes) Rate = 10°C / min Injection port temperature: 220°C AUX temperature: 230°C Ion source temperature: 230°C Split ratio: 10:1 Flow rate: 2.0 mL / min Average linear velocity: 37 cm / s Injection volume: 1 μL Measurement mode: SIM

[0097] <Method for evaluating heat resistance> As an index of the heat resistance of the resin compositions obtained in the Examples and Reference Examples, the heat distortion temperature (hereinafter referred to as "HDT") (°C) was measured in accordance with JIS K 7191 for test pieces (length 127 mm × width 12.7 mm × thickness 3 mm) of the resin molded articles obtained in the Examples and Reference Examples.

[0098] [Light stability evaluation] As an index of the light stability of the resin compositions produced in the Examples and Reference Examples, the change in the yellowness index (ΔYI) was used.

[0099] [Light stability test] The light stability test was carried out using a Metal Weather super accelerated light stability testing machine (manufactured by DAIPLA WINTES Co., Ltd., model name: DW-R8PL-A), which is equipped with a metal halide lamp (manufactured by DAIPLA WINTES Co., Ltd., model: MW-60W) and a light cut-off filter (manufactured by DAIPLA WINTES Co., Ltd., model: KF-1). Specifically, in the evaluation chamber of the Metal Weather super accelerated light stability testing machine, a test piece (square shape with length 50 mm × width 50 mm, thickness 3 mm) composed of the resin composition was set, and light was irradiated on the test piece from the metal halide lamp for 300 hours. The irradiation intensity of UV was corrected to 130 mW / cm at wavelengths of 300 to 400 nm measured by an ultraviolet illuminometer (manufactured by USHIO Electric Co., Ltd., model name: UVP-365-03). 2 Visible light and UV from the metal halide lamp were irradiated on the test piece. The evaluation chamber of the Metal Weather super accelerated light stability testing machine was set in an environment of temperature 63 °C and humidity 50 RH%.

[0100] [Manufacture of resin composition] [Example 1] (1) Manufacture of slurry 1-Octene as an α-olefin and methyl propionate were added to a reactor (polymerization kettle) equipped with a condenser, a thermometer, and a stirrer. Methyl methacrylate was further supplied, and nitrogen was bubbled while stirring, and then heating was started. When the internal temperature of the reactor reached 80 °C, 0.12 part of 2,2'-azobis(2,4-dimethylvaleronitrile) as a radical polymerization initiator and 0.075 part of 1-dodecanethiol as a chain transfer agent were added. After further heating until the internal temperature of the reactor reached 100 °C, it was maintained for 9 minutes. Then, the internal temperature of the reactor was cooled to room temperature to obtain the following slurry, which contained 500 ppm of 1-octene and at least one compound selected from the group consisting of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate. The content of the polymer in the slurry was 25% by mass based on the total mass of the slurry.

[0101] (2) Cast polymerization To 100 parts of the above slurry, 0.15 part of tert-hexyl perneodecanoate as a radical polymerization initiator was added to obtain a polymerizable composition (X2). Then, the polymerizable composition (X2) was poured into a space with a gap interval of 6.5 mm formed by disposing a soft resin gasket at the end of SUS plates between two opposed SUS plates, heated at 80 °C for 30 minutes, and then heated at 130 °C for 30 minutes to cure the polymerizable composition (X2) to obtain a resin composition. The composition of the resin composition is shown in Table 1. Then, after cooling the (meth)acrylic resin composition together with the SUS plates, the SUS plates were removed to obtain a plate-shaped resin molded body with a thickness of 5 mm. The evaluation results of the characteristics of the obtained resin molded body are shown in Table 1. It should be noted that in Table 1, "-" indicates that the measurement was not performed.

[0102] [Examples 2 to 7, Comparative Examples 1 to 6] Except that the composition of the monomer composition was changed as described in Tables 1 and 2, resin compositions and resin molded bodies were produced in the same manner as in Example 1. The compositions of the obtained resin compositions are shown in Tables 1 and 2. The evaluation results of the characteristics of the obtained resin molded bodies are shown in Tables 1 and 2.

[0103] In Examples 1 to 10, the following monomer composition was used. The monomer composition contains methyl methacrylate, an α-olefin, and at least one compound selected from the group consisting of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate. Among them, with respect to the total mass of the monomer composition, the total content of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate is greater than 36 mass ppm. The α-olefin contains at least one monomer selected from the group consisting of 2-ethyl-1-hexene, 1-octene, and 1-dodecene. The resin composition obtained by polymerizing these monomer compositions is a resin composition containing a methacrylic polymer (P), an α-olefin, and at least one compound selected from the group consisting of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate. Among them, the total content of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate is greater than 26 mass ppm. The α-olefin contains at least one monomer selected from the group consisting of 2-ethyl-1-hexene, 1-octene, and 1-dodecene. It is known that the resin molded article obtained by molding these resin compositions maintains the transparency and heat resistance inherent in the methacrylic resin and has excellent light stability.

[0104] On the other hand, although the monomer compositions of Reference Examples 1, 2, 4, and 5 contain an α-olefin, the total content of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate is 36 mass ppm or less. The monomer composition of Reference Example 3 does not contain an α-olefin, and the total content of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate is also 36 mass ppm or less. Although the total content of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate in the monomer compositions of Reference Examples 6 and 7 is greater than 36 mass ppm, they do not contain an α-olefin. In addition, although the resin compositions of Reference Examples 1, 2, 4, and 5 contain an α-olefin, the total content of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate is 26 mass ppm or less. The monomer composition of Reference Example 3 does not contain an α-olefin, and the total content of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate is also 26 mass ppm or less. Although the total content of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate in the monomer compositions of Reference Examples 6 and 7 is greater than 36 mass ppm, they do not contain an α-olefin.

[0105] When comparing Examples 1 to 10 with Reference Example 3, it can be seen that the resin molded articles obtained in Examples 1 to 10 maintain the same properties as the transparency and heat resistance inherent in the conventional resin molded articles formed from methacrylic resins. The transparency (YI at 0 hours of light irradiation) required for a general methacrylic resin molded article is 0.5 or less, and the heat resistance (HDT) is 100°C or higher. Therefore, it can be seen that the transparency and heat resistance of the resin molded articles obtained in Examples 1 to 10 exceed the standards required for general methacrylic resin molded articles.

[0106] Furthermore, when Examples 1 to 10 were compared with Reference Examples 1 to 7, it was found that the light stability of the resin molded articles obtained in Examples 1 to 10 was also significantly higher than that of the molded articles obtained in Reference Examples 1 to 7.

[0107] In addition, from Examples 1 to 10, it was found that as long as the monomer composition and the resin composition contain an α-olefin and at least one compound selected from the group consisting of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate in a specific amount or more, regardless of the content thereof, a resin molded article having excellent transparency, heat resistance, and light stability can be obtained.

[0108] Furthermore, in Example 10, the monomer composition and the resin composition contained an α-olefin and at least one compound selected from the group consisting of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate, and further contained two compounds selected from the group consisting of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate. From Example 10, it was found that as long as the total content of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate is a specific amount or more, in the case of selecting any compound, the following resin molded article can also be obtained. The resin molded article has the same transparency and heat resistance as the conventional methacrylic resin molded article, and also exhibits particularly high light stability.

[0109] [Table 1]

[0110] [Table 2]

Claims

1. A monomer composition, characterized in that, comprising: methyl methacrylate, an α-olefin, and at least one compound selected from the group consisting of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate, the total content of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate is greater than 36 mass ppm relative to the total mass of the monomer composition, the α-olefin includes at least one selected from the group consisting of 2-ethyl-1-hexene, 1-octene, and 1-dodecene.

2. The monomer composition according to claim 1, wherein, the content of methyl methacrylate is 85 mass% or more relative to the total mass of the monomer composition.

3. The monomer composition according to claim 1 or 2, wherein, the content of methyl methacrylate is 90 mass% or more relative to the total mass of the monomer composition.

4. The monomer composition according to any one of claims 1 to 3, wherein, the content of the α-olefin is 0.1 mass ppm or more relative to the total mass of the monomer composition.

5. The monomer composition according to any one of claims 1 to 4, wherein, the content of the α-olefin is 10 mass ppm or more relative to the total mass of the monomer composition.

6. The monomer composition according to any one of claims 1 to 5, wherein, the content of the α-olefin is 60 mass ppm or more relative to the total mass of the monomer composition.

7. The monomer composition according to any one of claims 1 to 6, wherein, the content of the α-olefin is 80 mass ppm or more relative to the total mass of the monomer composition.

8. The monomer composition according to any one of claims 1 to 7, wherein, The content of at least one compound selected from the group consisting of a compound of a transition metal and a compound of a Group 13 element is 2×10 4 mass ppm or less, relative to the total mass of the α-olefin.

9. The monomer composition according to any one of claims 1 to 8, wherein, the total content of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate is 40 mass ppm or more relative to the total mass of the monomer composition.

10. The monomer composition according to any one of claims 1 to 9, wherein, the total content of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate is 60 mass ppm or more relative to the total mass of the monomer composition.

11. The monomer composition according to any one of claims 1 to 10, wherein, the total content of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate is 70 mass ppm or more relative to the total mass of the monomer composition.

12. The monomer composition according to any one of claims 1 to 11, wherein, the total content of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate is 100 mass ppm or more relative to the total mass of the monomer composition.

13. The monomer composition according to any one of claims 1 to 12, wherein, the ratio of the content of the α-olefin to the total content of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate, i.e., [mass of the α-olefin] / [total mass of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate], is 0.00001 or more and 1,000 or less.

14. The monomer composition according to any one of claims 1 to 13, further comprising acrylate.

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

16. The monomer composition according to claim 14, wherein, the acrylate is methyl acrylate or ethyl acrylate.

17. The monomer composition according to any one of claims 1 to 16, further comprising styrene.

18. The monomer composition according to any one of claims 1 to 17, further comprising methyl isobutyrate.

19. A method for producing a resin composition, which includes a radical polymerization step of subjecting a polymerizable composition to radical polymerization, wherein the polymerizable composition contains the monomer composition according to any one of claims 1 to 18.

20. A resin composition, which contains a polymer of the monomer composition according to any one of claims 1 to 18.

21. A resin composition, characterized in that comprising: a methacrylic polymer P, an α-olefin, and at least one compound selected from the group consisting of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate, the total content of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate is greater than 26 mass ppm relative to the total mass of the resin composition, the α-olefin includes at least one selected from the group consisting of 2-ethyl-1-hexene, 1-octene, and 1-dodecene.

22. The resin composition according to claim 21, wherein the methacrylic polymer P contains 50 mass% or more of repeating units derived from methyl methacrylate relative to the total mass of the methacrylic polymer P.

23. The resin composition according to claim 21 or 22, wherein the methacrylic polymer P contains 70 mass% or more of repeating units derived from methyl methacrylate relative to the total mass of the methacrylic polymer P.

24. The resin composition according to any one of claims 21 to 23, wherein The content of the α-olefin is 0.1 mass ppm or more relative to the total mass of the resin composition.

25. The resin composition according to any one of claims 21 to 24, wherein The content of the α-olefin is 10 mass ppm or more relative to the total mass of the resin composition.

26. The resin composition according to any one of claims 21 to 25, wherein The content of the α-olefin is 60 mass ppm or more relative to the total mass of the resin composition.

27. The resin composition according to any one of claims 21 to 26, wherein The content of the α-olefin is 80 mass ppm or more relative to the total mass of the resin composition.

28. The resin composition according to any one of claims 21 to 27, wherein The total content of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate is 30 mass ppm or more relative to the total mass of the resin composition.

29. The resin composition according to any one of claims 21 to 28, wherein The total content of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate is 40 mass ppm or more relative to the total mass of the resin composition.

30. The resin composition according to any one of claims 21 to 29, wherein The total content of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate is 60 mass ppm or more relative to the total mass of the resin composition.

31. The resin composition according to any one of claims 21 to 30, wherein The total content of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate is 80 mass ppm or more relative to the total mass of the resin composition.

32. The resin composition according to any one of claims 21 to 31, wherein The resin composition further contains methyl isobutyrate.

33. The resin composition according to any one of claims 21 to 32, wherein The methacrylic polymer P contains repeating units derived from methyl methacrylate and repeating units derived from an acrylate.

34. The resin composition according to any one of claims 21 to 32, wherein The methacrylic polymer P contains repeating units derived from methyl methacrylate and repeating units derived from styrene.

35. A resin molded article, which contains the resin composition according to any one of claims 20 to 34.

36. A vehicle component comprising the resin molded body according to claim 35.

37. A medical component comprising the resin molded body according to claim 35.

38. A toy comprising the resin molded body according to claim 35.

39. A liquid container comprising the resin molded body according to claim 35.

40. An optical material comprising the resin molded body according to claim 35.

41. A billboard comprising the resin molded body according to claim 35.

42. A display comprising the resin molded body according to claim 35.

43. A method for manufacturing a resin molded body, wherein, A forming step of forming a resin composition is included, the resin composition containing a methacrylic polymer P, an α-olefin, and at least one compound selected from the group consisting of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate. The total content of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate in the resin composition is greater than 26 mass ppm relative to the total mass of the resin composition. The α-olefin contains at least one selected from the group consisting of 2-ethyl-1-hexene, 1-octene, and 1-dodecene.

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