Monomer composition, resin composition, method for manufacturing a resin composition, resin molded article, and method for manufacturing a resin molded article.

Abstract

Provided is a monomer composition 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, wherein: the total content value for methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate is greater than 36 mass ppm relative to the total mass of the monomer composition; and the α-olefin contains at least one 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 the resin composition, a resin molded body, and a method for producing the resin molded body.

Background Art

[0002] Methacrylic resins are excellent in transparency, heat resistance, and weather resistance, and have balanced performance in resin physical properties such as mechanical strength, thermal properties, and molding processability. Due to such excellent characteristics, they are used in many applications such as vehicle members, medical members, toys, liquid containers, optical materials, signboards, displays, decorative members, building members, and front panels of electronic devices, and are particularly used for members having light transmittance.

[0003] In the above applications, when a member in which a methacrylic resin plate is used is installed 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 greatly reduced. Therefore, there has been a demand for a methacrylic resin that maintains its transparency even when exposed to light for a long time, that is, a methacrylic resin having 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-based compound as a structural unit.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

[0006] However, the methacrylic resins described in Patent Documents 1 and 2 had a problem in that, while photostability improved with increasing amounts of additives during polymerization, discoloration caused by the additives occurred. Therefore, they could not be used when a specific color tone and transparency were required simultaneously.

[0007] Based on the above circumstances, the object of the present invention is to provide a monomer composition, a resin composition, a method for producing a resin composition, a molded resin article, and a method for producing a molded resin article, for obtaining a resin composition with excellent photostability while maintaining the transparency and heat resistance inherent in methacrylic resins. [Means for solving the problem]

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

[0009] [1] A monomeric composition 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 ppm by mass relative to the total mass of the monomer composition. A monomeric composition wherein the α-olefin comprises 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% by 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% by 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 ppm by mass 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 ppm by mass 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 ppm by mass 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 ppm by mass or more with respect to the total mass of the monomer composition. [8] The content of at least one compound selected from the group consisting of transition metal compounds and group 13 element compounds is 2 × 10¹⁶ relative to the total mass of the α-olefin. 4 A monomer composition according to any one of [1] to [7], wherein the mass is less than or equal to ppm. [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 ppm by mass or more based on 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 ppm by mass or more based on 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 ppm by mass or more based on 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 ppm by mass or more based on the total mass of the monomer composition.

[13] 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, and the monomer composition according to any one of [1] to

[12] .

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

[13] , further containing an acrylate ester.

[15] The monomer composition according to

[14] , wherein the acrylate ester 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 ester is methyl acrylate or ethyl acrylate.

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

[16] , further containing styrene.

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

[17] , further containing methyl isobutyrate.

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

[18] .[[]]

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

[18] .[[]]

[21] A resin composition 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, where the total content of methyl propionate, methyl pyruvate and methyl 2-methylbutyrate is more than 26 ppm by mass based on the total mass of the resin composition, A resin composition in which 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 a repeating unit derived from methyl methacrylate in an amount of 50% by mass or more based on the total mass of the methacrylic polymer (P). 〔23〕 The resin composition according to

[21] or

[22] , wherein the methacrylic polymer (P) contains a repeating unit derived from methyl methacrylate in an amount of 70% by mass or more based on 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 based on 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 based on 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 based on 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 based on 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 based on 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 ppm by mass 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 ppm by mass or more based on the total mass of the resin composition.

[32] The resin composition according to any one of

[21] to

[31] , further containing methyl isobutyrate in the resin composition.

[33] The resin composition according to any one of

[21] to

[32] , wherein the methacrylic polymer (P) includes repeating units derived from methyl methacrylate and repeating units derived from acrylic acid ester.

[34] The resin composition according to any one of

[21] to

[32] , wherein the methacrylic polymer (P) comprises repeating units derived from methyl methacrylate and repeating units derived from styrene.

[35] A resin molded article comprising the resin composition described in any of

[20] to

[34] .

[36] A vehicle component including the resin molded body described in

[35] .

[37] Medical component including the resin molded article described in

[35] .

[38] A toy, including the resin molded body described in

[35] .

[39] A liquid container including the resin molded body described in

[35] .

[40] Optical materials, including the resin molded articles described in

[35] .

[41] A sign, including the resin molded product described in

[35] .

[42] A display including the resin molded body described in

[35] .

[43] The process includes a molding step of molding a resin composition 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 in the resin composition is greater than 26 ppm by mass relative to the total mass of the resin composition. A method for producing a resin molded article, wherein the α-olefin comprises at least one selected from the group consisting of 2-ethyl-1-hexene, 1-octene, and 1-dodecene. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a monomer composition, a resin composition, a method for producing the resin composition, a molded resin article, and a method for producing the molded resin article, which are capable of obtaining a resin composition with excellent photostability while maintaining the transparency and heat resistance inherent in methacrylic resins. [Modes for carrying out the invention]

[0011] The following terms used in this specification and in the claims are defined as follows: A "monomer" refers to a compound that has a polymerizable carbon-carbon double bond. "Repeating units" refer to units derived from monomers formed by the polymerization of monomers. Repeating units may be units directly formed by the polymerization reaction, or they may be units in which a portion of the polymer has been converted to a different structure by processing the polymer. "(Meth)acrylate" refers to either "acrylate" or "methacrylate," or both. "(Meth)acryloyl" means either "acryloyl" or "methacryloyl," or both. "(Meth)acrylic acid" refers to either or both "acrylic acid" and "methacrylic acid." "Conjugation" refers to the overlap of p orbitals beyond the sigma bond between them. "Non-conjugated" means that conjugation does not occur. "The resulting resin composition" means a resin composition obtained by radical polymerization of a monomer mixture containing a monomer composition. "The obtained resin molded article" refers to a resin molded article obtained by molding a resin composition. "Mass %" indicates the percentage of a given component contained in 100% of the total amount by mass. "Mass-average molecular weight" is a value measured using gel permeation chromatography with standard polystyrene as the standard sample. "UV" and "ultraviolet light" refer to light that primarily includes light with a wavelength range of 295 to 430 nm.

[0012] "Transition metals" refer to metallic elements located in groups 3 through 12 of the periodic table. Typically, these include 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), and praseodymium (Pr). These include 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). "Group 13 elements" refers to elements located in Group 13 of the periodic table. Typical examples include boron (B), aluminum (Al), gallium (Ga), indium (In), and thallium (Tl). "Periodic Table" refers to the "Periodic Table of Elements" ("Periodic Table of Elements", [online], National Center for Biotechnology Information, [Accessed November 7, 2022], Internet).<URL: https: / / pubchem.ncbi.nlm.nih.gov / periodic-table / > ) means.

[0013] In this specification, a numerical range represented by "~" means a range that includes the numbers written before and after "~" as the lower and upper limits, respectively, and "A~B" means that it is greater than or equal to A and less than or equal to B.

[0014] <1. Monomer Composition> A monomer composition according to the first embodiment of the present invention comprises methyl methacrylate, an α-olefin, and at least one compound selected from the group consisting of propionic acid, methyl pyruvate, and methyl 2-methylbutyrate, wherein the total content of methyl propionic acid, methyl pyruvate, and methyl 2-methylbutyrate is greater than 36 ppm by mass relative to the total mass of the monomer composition, and the α-olefin comprises at least one selected from the group consisting of 2-ethyl-1-hexene, 1-octene, and 1-dodecene (hereinafter, unless otherwise specified, "α-olefin" refers to at least one selected from the group consisting of 2-ethyl-1-hexene, 1-octene, and 1-dodecene). In addition, other components may be included to the extent that they do not impair the effects of the present invention.

[0015] <1-1. Methyl methacrylate> The monomer composition according to this embodiment contains methyl methacrylate. Methyl methacrylate can be produced by methods such as the acetone cyanohydrin method, the new acetone cyanohydrin method, the C4 direct oxidation method, the direct methacrylate method, the ethylene method, and the new ethylene method. Alternatively, methyl methacrylate obtained by thermal decomposition of a resin composition polymerized from a monomer composition containing methyl methacrylate may be used. It is more preferable that the methyl methacrylate is obtained by thermal decomposition of a resin composition polymerized from a monomer composition containing methyl methacrylate. By containing methyl methacrylate, the monomer composition according to this embodiment can provide a resin composition that ensures excellent photostability and the inherent heat resistance of methacrylic resins.

[0016] The lower limit of the methyl methacrylate content relative to the total mass of the monomer composition is not particularly limited, but it is preferably 85% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and particularly preferably 97% by mass or more. The upper limit of the methyl methacrylate content is also not particularly limited, but it is usually 99.99% by mass or less, and may 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 97% by mass or more and 99.97% by mass or less can be cited.

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

[0018] <1-2. α-olefins> The monomer composition according to this embodiment contains an α-olefin selected from the group consisting of 2-ethyl-1-hexene, 1-octene, and 1-dodecene, thereby providing a resin composition with excellent photostability. The α-olefin may be used alone, or two or more may be used in any ratio and combination.

[0019] The lower limit of the α-olefin content relative to the total mass of the monomer composition according to this embodiment is not particularly limited, but it is preferably 0.1 ppm by mass or more, more preferably 10 ppm by mass or more, even more preferably 60 ppm by mass or more, even more preferably 80 ppm by mass or more, and particularly preferably 100 ppm by mass or more, in order to provide a resin composition with good photostability.

[0020] The upper limit of the α-olefin content in the monomer composition according to this embodiment is not particularly limited, but it is preferably 10,000 ppm by mass or less, more preferably 5,000 ppm by mass or less, even more preferably 4,000 ppm by mass or less, even more preferably 3,000 ppm by mass or less, and particularly preferably 2,000 ppm by mass or less, in order to provide a resin composition that can maintain good heat resistance.

[0021] The preferred upper and lower limits mentioned above can be combined in any way. Specifically, the content of α-olefins relative to the total mass of the monomer composition according to this embodiment is preferably 0.1 ppm or more and 10,000 ppm or less, more preferably 10 ppm or more and 5,000 ppm or less, even more preferably 60 ppm or more and 4,000 ppm or less, even more preferably 80 ppm or more and 3,000 ppm or less, and particularly preferably 100 ppm or more and 2,000 ppm or less. If the monomer composition contains two or more types of α-olefins, the above content is the total content of the two or more types of α-olefins.

[0022] The aforementioned α-olefin is presumed to have excellent radical scavenging properties because the coupling products of olefins to which radicals generated by ultraviolet light are attached are stable.

[0023] 2-ethyl-1-hexene, 1-octene, and 1-dodecene tend to remain in the resulting resin composition without volatilizing during polymerization heating. Therefore, they can significantly contribute to improving the photostability of the resin composition obtained by polymerization of monomer compositions. At least one α-olefin selected from the group consisting of 2-ethyl-1-hexene, 1-octene, and 1-dodecene is likely to exhibit a photostability-improving effect even in small amounts. As described later, the photostability-improving effect of α-olefins is thought to involve hydrogen atoms bonded to carbon atoms adjacent to the double bond. Therefore, even with the same mass, a smaller number of carbon atoms results in a larger number of carbon atoms involved in the double bond within one α-olefin molecule, making it easier to exhibit a photostability-improving effect.

[0024] As the α-olefin, one or more selected from 1-octene and 2-ethyl-1-hexene are more preferred among 2-ethyl-1-hexene, 1-octene, and 1-dodecene, and 1-octene is even more preferred because it tends to remain in the resin composition after polymerization. The proportion of 1-octene in the α-olefin is not particularly limited, but is preferably 50% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and usually 100% by mass or less, based on the total mass of the α-olefin.

[0025] In the monomer composition according to this embodiment, the content of at least one compound selected from the group consisting of transition metal compounds and group 13 element compounds is 0 ppm or more by mass, relative to the total mass of α-olefin, which is 2 × 10⁻¹⁶. 4 It is preferable that the mass be less than or equal to ppm.

[0026] In this embodiment, the α-olefin exhibits significantly lower reactivity compared to methyl methacrylate, which is a conjugated monomer, and does not provide resonance stabilization. Therefore, unless a specific polymerization catalyst is used, such as at least one compound selected from the group consisting of transition metal compounds and group 13 element compounds, and special conditions are met to exhibit catalytic effects, unreacted α-olefins (hereinafter also referred to as "α-olefin monomers") remain in the resulting resin composition. It is believed that the presence of α-olefin monomers in the resin composition provides a resin composition with good photostability. In other words, because the at least one compound does not exhibit catalytic effects, the content of the at least one compound is 2 × 10⁻¹⁶ of the total mass of α-olefin. 4 Preferably, the mass is less than or equal to 1 × 10¹⁶ ppm. 4 It is more preferable that the amount is less than or equal to ppm by mass, even more preferable that it is less than or equal to 1,000 ppm by mass, particularly preferable that it is less than or equal to 500 ppm by mass, and particularly preferable that it is not present at all. Here, "not present" means that it is below the detection limit.

[0027] Examples of the at least one compound include compounds of transition metals from groups 5 to 11 having a chelating ligand, and Lewis acid catalysts. Specific examples of the transition metals include vanadium, niobium, tantalum, chromium, molybdenum, tungsten, manganese, iron, platinum, ruthenium, cobalt, rhodium, nickel, palladium, and copper. Among these, transition metals from groups 8 to 11 are preferred, transition metals from group 10 are more preferred, and nickel (Ni) or palladium (Pd) is even more preferred. These transition metals may be used individually or in combination of two or more.

[0028] The chelating ligand contains at least two atoms selected from the group consisting of P, N, O, and S, and is bidentate or multidentate, and is electronically neutral or anionic. The structure of the chelating ligand is illustrated in a 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). Examples of the chelating ligand include the bidentate anionic P,O ligand. Examples of the bidentate anionic P,O ligand include phosphosulfonic acid, phosphocarboxylic acid, phosphorusphenol, and phosphorus enolate. Examples of chelating ligands other than the bidentate anionic P,O ligand include the bidentate anionic N,O ligand. Examples of the bidentate anionic N,O ligands include salicylaldehyde and pyridinecarboxylic acid. Examples of chelating ligands other than the bidentate anionic P,O ligands and bidentate anionic N,O ligands include diimine ligands, diphenoxide ligands, and diamide ligands.

[0029] Here, typical catalysts that are compounds of transition metals from groups 5 to 11 having the aforementioned chelating ligand include so-called SHOP catalysts and Drent catalysts. The SHOP catalyst is a catalyst in which a phosphorus ligand having an aryl group, which may have substituents, is coordinated to nickel metal. The Drent catalyst is a catalyst in which a phosphorus ligand having an aryl group, which may have substituents, is coordinated to palladium metal.

[0030] Furthermore, typical Lewis acid catalysts include cationic complexes of divalent palladium or platinum. These cationic complexes of divalent palladium or platinum exhibit Lewis acidity and are useful as Lewis acid catalysts for reactions such as the Diels-Alder reaction. Compounds of group 13 elements boron and aluminum, the fourth transition metal titanium, and the fifth transition metal zirconium are also preferred because they exhibit Lewis acidity.

[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 according to this embodiment. A resin composition with excellent photostability can be provided if the total content of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate relative to the total mass of the monomer composition is greater than 36 ppm by mass. If 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, if only one of the three compounds is contained, the content of that one compound should be greater than 36 ppm by mass, and if all three compounds are contained, the total content of the three compounds should be greater than 36 ppm by mass.

[0032] The lower limit of the total content of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate relative to the total mass of the monomer composition according to this embodiment is not particularly limited, but is usually greater than 36 ppm by mass, preferably 40 ppm by mass or more, more preferably 60 ppm by mass or more, even more preferably 70 ppm by mass or more, even more preferably 80 ppm by mass or more, and particularly preferably 100 ppm by mass or more, in order to provide a resin composition with good photostability.

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

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

[0035] In the monomer composition according to this 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 the ratio of "[mass of α-olefin] / [total mass of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate]") is not particularly limited, but it is preferably 1,000 or less, more preferably 500 or less, even more preferably 300 or less, even more preferably 100 or less, and particularly preferably 10 or less, in that 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 can provide a resin molded article with good photostability. The lower limit of the ratio of [mass of α-olefin] / [total mass of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate] is not particularly limited, but from the viewpoint of having good heat resistance of the resin molded article, it is preferably 0.00001 or higher, more preferably 0.0001 or higher, even more preferably 0.001 or higher, even more preferably 0.01 or higher, and particularly preferably 0.5 or higher.

[0036] The above upper and lower limits can be combined in any way. For example, preferred ranges for the ratio of [mass of α-olefin] / [total mass of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate] include 0.00001 to 1,000, 0.0001 to 500, 0.001 to 300, 0.01 to 100, and 0.5 to 10. Of these, the ratio of [mass of α-olefin] / [total mass of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate] is more preferably 0.0001 to 500, and even more preferably 0.001 to 300.

[0037] <1-4. Monomers other than methyl methacrylate> The monomer composition according to this embodiment may contain monomers other than methyl methacrylate. In this specification, "monomer" means an unpolymerized compound. Examples of monomers other than methyl methacrylate include the monomers listed in (1) to (16) below. The monomers listed in (1) to (16) below can be used individually or in any ratio and combination of two or more. (1) Methacrylic acid ester: For example, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, iso-butyl methacrylate, tert-butyl methacrylate, 2-ethylhexyl methacrylate, phenyl methacrylate, or benzyl methacrylate. (2) Acrylates: For example, methyl acrylate, ethyl acrylate, n-butyl acrylate, iso-butyl acrylate, tert-butyl acrylate, or 2-ethylhexyl acrylate. (3) Unsaturated carboxylic acids: For example, acrylic acid, methacrylic acid, maleic acid, or itaconic acid. (4) Unsaturated carboxylic acid anhydrides: For example, maleic anhydride or itaconic anhydride. (5) Maleimide: For example, N-phenylmaleimide or N-cyclohexylmaleimide. (6) Hydroxyl group-containing vinyl monomers: For example, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, or 2-hydroxypropyl methacrylate. (7) Vinyl ester: For example, vinyl acetate or vinyl benzoate. (8) Vinyl chloride, vinylidene chloride, or derivatives thereof. (9) Nitrogen-containing vinyl monomers: For example, methacrylamide or acrylonitrile. (10) Epoxy group-containing monomers: For example, glycidyl acrylate or glycidyl methacrylate. (11) Aromatic vinyl monomers: For example, styrene, or alpha-methylstyrene. (12) Alkanediolic di(meth)acrylate: For example, ethylene glycol di(meth)acrylate, 1,2-propylene glycol di(meth)acrylate, 1,3-butylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, or 1,6-hexanediol di(meth)acrylate. (13) Polyalkylene 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) An unsaturated polyester prepolymer obtained from at least one polycarboxylic acid containing an ethylenically unsaturated polycarboxylic acid and at least one diol. (16) A vinyl ester prepolymer obtained by modifying the terminals of epoxy groups with acrylic.

[0038] Of these, the monomer is preferably at least one acrylic acid ester selected from the group consisting of methyl acrylate, ethyl acrylate, and n-butyl acrylate, and more preferably methyl acrylate or ethyl acrylate, in order to provide a resin composition with an excellent balance of transparency, heat resistance, and moldability. Furthermore, the content of this acrylic acid ester is preferably 0% by mass or more and 30% by mass or less based on the total mass of the monomer composition. By including an acrylic acid ester in the monomer composition, a resin composition with excellent photostability can be provided. In addition, the decrease in photostability when a resin molded article containing this resin composition is exposed to light for a long period of time can be suppressed. Furthermore, by changing the acrylic acid ester 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"). In this case, the styrene content can be the same as the styrene unit content ratio described in <3-2. Methacrylic Polymer (P)>.

[0039] <1-5. Methyl isobutyrate> Preferably, the monomer composition further contains methyl isobutyrate. Including this compound provides a resin composition with even better photostability. This is presumed to further enhance the photostability improvement effect caused by including α-olefin and at least one compound selected from the group consisting of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate in specific amounts, as described in <3-1. Effects>. Furthermore, it is possible to suppress the decrease in photostability when a resin molded article containing this resin composition is exposed to light for a long period of time.

[0040] When the monomer composition according to this embodiment contains methyl isobutyrate, it is preferable that the total content of methyl isobutyrate, methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate relative to the total mass of the monomer composition is within the range of the total content of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate described above.

[0041] Furthermore, if the monomer composition according to this embodiment contains methyl isobutyrate, the content of methyl isobutyrate relative to the total mass of the monomer composition is preferably 10 ppm by mass or more, more preferably 50 ppm by mass or more, even more preferably 100 ppm by mass or more, particularly preferably 200 ppm by mass or more, most preferably 250 ppm by mass or more, and also preferably 10,000 ppm by mass or less, more preferably 8,000 ppm by mass or less, even more preferably 5,000 ppm by mass or less, particularly preferably 3,000 ppm by mass or less. Down Most preferably, 1,500 ppm by mass or less. Down That is the case.

[0042] The above preferred upper and lower limits can be combined in any way. Specifically, preferred ranges for the methyl isobutyrate content relative to the total mass of the monomer composition according to this embodiment include 10 ppm to 10,000 ppm, 50 ppm to 8,000 ppm, 100 ppm to 5,000 ppm, 200 ppm to 3,000 ppm, and 250 ppm to 1,500 ppm.

[0043] <1-6. Additives> The monomer composition according to this embodiment may contain other additives. Examples of known additives include mold release agents, heat stabilizers, lubricants, plasticizers, antioxidants, antistatic agents, light stabilizers (other than α-olefins, methyl isobutyrate, methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate), ultraviolet absorbers, flame retardants, flame retardant aids, fillers, pigments, dyes, silane coupling agents, leveling agents, defoamers, and fluorescent agents. The additives can be used individually or in any combination of two or more in any ratio and combination.

[0044] In this embodiment, the α-olefin and at least one compound selected from the group consisting of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate are thought to exhibit superior photostability through a mechanism of action different from that of generally known UV absorbers and radical scavengers (HALS). Therefore, it is possible to use the α-olefin and at least one compound selected from the group consisting of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate in combination with additives such as UV absorbers and HALS. By including the α-olefin, at least one compound selected from the group consisting of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate, and the additive in the monomer composition, it is possible to provide resin compositions and resin molded articles with increased photostability.

[0045] Furthermore, the monomer composition according to this embodiment may contain compounds that inevitably become mixed with methyl methacrylate, such as methacrolein and methanol.

[0046] <2. Polymerizable composition> The polymerizable composition according to the second embodiment of the present invention is one form of raw material for obtaining the resin composition according to the third embodiment of the present invention, which will be described later. The polymerizable composition according to this embodiment (also referred to as "polymerizable composition (X2)") is, for example, a polymerizable composition comprising the monomer composition and, optionally, a known radical polymerization initiator.

[0047] <2-1. Radical polymerization initiators> Examples of radical polymerization initiators include known azo compounds such as 2,2'-azobis(isobutyronitrile) and 2,2'-azobis(2,4-dimethylvaleronitrile); and known organic peroxides such as benzoyl peroxide and lauroyl peroxide. These can be used individually or in any ratio and combination of two or more. In addition, known polymerization accelerators such as amines and mercaptans 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 can be appropriately determined by those skilled in the art in accordance with well-known technology. Specifically, the content of the radical polymerization agent may be 0.005 parts by mass or more and 5 parts by mass or less, or 0.01 parts by mass or more and 1.0 part by mass or less, per 100 parts by mass of the total mass of the polymerizable composition (X2).

[0049] <2-2. Additives> The form of the additive is the same as described in <1-6. Additives>. The additive may be one type or two or more types.

[0050] <3.Resin composition> A resin composition according to a 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, wherein the total content of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate is greater than 26 ppm by mass relative to the total mass of the resin composition, and the α-olefin contains at least one selected from the group consisting of 2-ethyl-1-hexene, 1-octene, and 1-dodecene. If 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, if only one of the three compounds is contained, the content of that one compound must be greater than 26 ppm by mass; if all three compounds are contained, the total content of the three compounds must be greater than 26 ppm by mass. The resin composition according to this embodiment may be a composition containing a polymer of the monomer composition according to the first embodiment of the present invention, or it may be a composition obtained by radical polymerization of a polymerizable composition according to the second embodiment of the present invention.

[0051] The resin composition according to this embodiment, by containing a methacrylic polymer (P), can provide a resin molded article with excellent heat resistance and good transparency. The resin composition, comprising a methacrylic polymer (P), includes an α-olefin and at least one compound selected from the group consisting of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate in specific amounts. This ensures that the α-olefin and at least one compound selected from the group consisting of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate exist in monomeric form within the polymerization chain of the methacrylic polymer (P). This suppresses the occurrence of yellowing even after prolonged exposure to UV light, and further suppresses the decrease in photostability, resulting in a resin molded article. While the form of the resin composition is not particularly limited, it is typically 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 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 described in <1-2. α-olefin>.

[0052] The content of methacrylic polymer (P) relative to the total mass of the resin composition is not particularly limited, but from the viewpoint of good 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, even more 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 photostability, this content is usually 99.99% by mass or less, preferably 99.9785% by mass or less, more preferably 99.97% by mass or less, even more preferably 99.95% by mass or less, and particularly preferably 99.90% by mass or less. The above upper and lower limits can be combined arbitrarily. For example, preferred content of methacrylic polymer (P) ranges from 80.0% by mass to 99.99% by mass, 85.0% by mass to 99.97% by mass, 90.0% by mass to 99.97% by mass, 95.0% by mass to 99.95% by mass, and 99.0% by mass to 99.90% by mass. If the resin composition contains two or more types of methacrylic polymer (P), the above content refers to the total content of the two or more types of methacrylic polymer (P).

[0053] The content of α-olefin relative to the total mass of the resin composition is not particularly limited, but from the viewpoint of obtaining excellent photostability, it is usually 0.1 ppm by mass or more, preferably 10 ppm by mass or more, more preferably 60 ppm by mass or more, even more preferably 80 ppm by mass or more, and particularly preferably 100 ppm by mass or more.

[0054] The upper limit of the α-olefin content relative to the total mass of the resin composition according to this embodiment is not particularly limited, but from the viewpoint of having good heat resistance of the resin molded article, it is usually 10,000 ppm by mass or less, preferably 5,000 ppm by mass or less, more preferably 4,000 ppm by mass or less, even more preferably 3,000 ppm by mass or less, and particularly preferably 2,000 ppm by mass or less.

[0055] The above upper and lower limits can be combined in any way. For example, preferred α-olefin content relative to the total mass of the resin composition includes ranges of 0.1 ppm to 10,000 ppm, 10 ppm to 5,000 ppm, 60 ppm to 4,000 ppm, 80 ppm to 3,000 ppm, and 100 ppm to 2,000 ppm. Of these, the α-olefin content is more preferably 10 ppm to 5,000 ppm, and even more preferably 100 ppm to 2,000 ppm.

[0056] The total content of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate relative to the total mass of the resin composition according to this embodiment is usually 26 ppm by mass or more, preferably 30 ppm by mass or more, more preferably 40 ppm by mass or more, even more preferably 60 ppm by mass or more, particularly preferably 80 ppm by mass or more, and most preferably 100 ppm by mass or more, from the viewpoint of obtaining excellent photostability.

[0057] The upper limit of the total content of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate relative to the total mass of the resin composition according to this embodiment is not particularly limited, but from the viewpoint of having good heat resistance of the resin molded article, it is preferably 20,000 ppm by mass or less, more preferably 15,000 ppm by mass or less, even more preferably 10,000 ppm by mass or less, particularly preferably 5,000 ppm by mass or less, and most preferably 3,000 ppm by mass or less.

[0058] The above upper and lower limits can be combined in any way. For example, the total content of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate can range from over 26 ppm by mass to 20,000 ppm by mass, 30 ppm by mass to 20,000 ppm by mass, 40 ppm by mass to 15,000 ppm by mass, 60 ppm by mass to 10,000 ppm by mass, 80 ppm by mass to 5,000 ppm by mass, and 100 ppm by mass to 3,000 ppm by mass. Of these, the total content of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate is more preferably 30 ppm by mass to 20,000 ppm by mass, and even more preferably 40 ppm by mass to 15,000 ppm by mass.

[0059] <3-1. Effects> A monomer composition according to the first embodiment of the present invention comprises methyl methacrylate, an α-olefin, and at least one compound selected from the group consisting of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate in specific amounts. A resin composition obtained by radical polymerization of a polymerizable composition (X2) containing the monomer composition exhibits excellent heat resistance, excellent light stability, and suppressed yellowing. The reason why the monomer composition according to 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 specific amounts, thereby obtaining a resin composition that ensures excellent heat resistance, has excellent light stability, and suppresses yellowing, is presumed to be as follows.

[0060] Polymers containing units based on methyl methacrylate (methacrylic polymers) undergo cleavage of the main chain or side chains upon exposure to light, generating radical species. Typically, these generated radical species cause yellowing of methacrylic resins and a decrease in mechanical strength due to a reduction in molecular weight.

[0061] However, the α-olefin contained in the monomer composition according to the first embodiment of the present invention and at least one compound selected from the group consisting of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate in specific amounts do not provide a resonance stabilization effect and are significantly less reactive compared to methyl methacrylate, which is a conjugated monomer. Therefore, unless under special conditions, the resulting resin composition contains unreacted α-olefin (also called α-olefin monomer) and at least one compound selected from the group consisting of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate (also called at least one compound monomer selected from the group consisting of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate). It is thought that this unreacted α-olefin and at least one compound selected from the group consisting of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate function as radical scavengers that capture the radical species. As a result, the unreacted α-olefin has a hydrogen atom bonded to a carbon atom adjacent to the double bond site removed, thereby capturing the radical species.

[0062] At this time, it is thought that at least one compound selected from the group consisting of unreacted methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate interacts with the unreacted α-olefin from which a hydrogen atom has been abstracted, and replaces the hydrogen atom, thereby allowing the α-olefin to function as a radical scavenger again. Therefore, it is thought that the photostability of the resulting resin composition is significantly improved not only by the effect of improving the photostability of the resin composition obtained by using α-olefin and at least one compound selected from the group consisting of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate alone, but also by the synergistic effect of using α-olefin and at least one compound selected from the group consisting of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate in combination.

[0063] In the resin composition according to this 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 the ratio of "[mass of α-olefin] / [total mass of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate]") is not particularly limited, but from the viewpoint of improving the photostability of the resin molded article 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, even more preferably 300 or less, even more preferably 100 or less, and particularly preferably 10 or less. The lower limit of the ratio of [mass of α-olefin] / [total mass of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate] is not particularly limited, but from the viewpoint of having good heat resistance of the resin molded article, it is preferably 0.00001 or higher, more preferably 0.0001 or higher, even more preferably 0.001 or higher, even more preferably 0.01 or higher, and particularly preferably 0.5 or higher.

[0064] The above upper and lower limits can be combined in any way. For example, preferred ranges for the ratio of [mass of α-olefin] / [total mass of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate] include 0.00001 to 1,000, 0.0001 to 500, 0.001 to 300, 0.01 to 100, and 0.5 to 10. Of these, the ratio of [mass of α-olefin] / [total mass of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate] is more preferably 0.0001 to 500, and even more preferably 0.001 to 300.

[0065] <3-2. Methacrylic polymer (P)> The methacrylic polymer (P) is one of the components included in the resin composition according to this embodiment. By including a methacrylic polymer (P) in the resin composition, transparency can be improved, decomposition due to heat and light can be suppressed, and heat moldability, heat resistance, and mechanical strength can be improved. Furthermore, due to the synergistic effect of the heat resistance inherent in the methacrylic polymer (P) and α-olefin and at least one compound selected from the group consisting of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate in specific amounts, it is possible to obtain a methacrylic resin molded article with high photostability and maintained heat resistance in the resulting resin composition.

[0066] The content of methyl methacrylate units in the methacrylic polymer (P) is not particularly limited, but from the viewpoint of good heat resistance, it is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, even more preferably 80% by mass or more, particularly preferably 90% by mass or more, and usually 100% by mass or less, based on the total mass of the methacrylic polymer (P).

[0067] The methacrylic polymer (P) is preferably a copolymer methacrylic polymer (P1) containing methyl methacrylate units and, optionally, repeating units derived from acrylic acid esters (hereinafter also referred to as "acrylic acid ester units") or styrene units. The arrangement of these copolymers is not particularly limited and may be, for example, a random copolymer, a block copolymer, or an alternating copolymer, but a random copolymer is preferred.

[0068] The repeating unit derived from the acrylic acid ester is a repeating unit derived from an acrylic acid ester having an alkyl group with 1 to 6 carbon atoms in its side chain. The monomer constituting this unit is not particularly limited as long as it is a monomer copolymerizable with methyl methacrylate. Examples include acrylic acid esters such as methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, or tert-butyl acrylate. These may be used individually or two or more in any ratio and combination. Among these monomers, from the viewpoint of ensuring high photostability, the resin molded article containing the resin composition is preferably at least one acrylic acid ester selected from the group consisting of methyl acrylate, ethyl acrylate, and n-butyl acrylate, and more preferably methyl acrylate or ethyl acrylate.

[0069] The content of methyl methacrylate units in the methacrylic polymer (P1) is not particularly limited, but from the viewpoint of good heat resistance, it is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, even more preferably 80% by mass or more, particularly preferably 90% by mass or more, and usually 100% by mass or less, based on the total mass of the methacrylic polymer (P1).

[0070] The content of acrylic acid ester units in the methacrylic polymer (P1) is not particularly limited, but from the viewpoint of good heat resistance and photostability, it is preferably 50% by mass or less, more preferably 30% by mass or less, even more preferably 20% by mass or less, particularly preferably 10% by mass or less, and usually 0% by mass or more. If the methacrylic polymer (P1) contains two or more types of acrylic acid ester units, the above content percentage is the total content percentage of the two or more types of acrylic acid ester units.

[0071] The styrene unit content in the methacrylic polymer (P1) is not particularly limited, but from the viewpoint of good transparency, it is preferably 50% by mass or less, more preferably 40% by mass or less, even more preferably 30% by mass or less, even more preferably 20% by mass or less, particularly preferably 10% by mass or less, and usually 0% by mass or more.

[0072] Furthermore, the methacrylic polymer (P) in this embodiment may contain structural units derived from polyfunctional monomers containing two or more radical polymerizable functional groups in one molecule (hereinafter referred to as "polyfunctional monomer units"), to the extent that the effects of the invention are obtained. The radical polymerizable functional group referred to herein can be any group having a carbon-carbon double bond and capable of radical polymerization. Specifically, examples include vinyl groups, allyl groups, (meth)acryloyl groups, and (meth)acryloyloxy groups. The (meth)acryloyl group is particularly preferred from the viewpoint of excellent storage stability of compounds having radical polymerizable functional groups and the ease with which the polymerizability of such compounds can be controlled. In a monomer having two radical polymerizable functional groups, each radical polymerizable functional group may be the same or different. The methacrylic polymer (P) can have improved solvent resistance or chemical resistance by containing polyfunctional monomer units.

[0073] Examples of polyfunctional monomers include, but are not limited to, allyl methacrylate, allyl acrylate, ethylene glycol di(meth)acrylate, ethylene glycol tri(meth)acrylate, neopentyl glycol di(meth)acrylate, and trimethylolpropane tri(meth)acrylate. These may be used individually or in any ratio and combination. Of these, the polyfunctional monomer is more preferably selected from ethylene glycol di(meth)acrylate and neopentyl glycol di(meth)acrylate, and even more preferably ethylene glycol di(meth)acrylate, from the viewpoint of obtaining better solvent resistance and chemical resistance.

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

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

[0076] <3-3. Methyl isobutyrate> Preferably, the resin composition further contains methyl isobutyrate. Including this compound provides a resin composition with even better photostability. This is presumed to further enhance the photostability improvement effect caused by including α-olefin and at least one compound selected from the group consisting of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate in specific amounts, as described in <3-1. Effects>. Furthermore, it is possible to suppress the decrease in photostability when a resin molded article containing this resin composition is exposed to light for a long period of time.

[0077] When the resin composition according to this embodiment contains methyl isobutyrate, it is preferable that the total content of methyl isobutyrate, methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate relative to the total mass of the resin composition is within the range of the total content of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate described above.

[0078] Furthermore, if the resin composition according to this embodiment contains methyl isobutyrate, the content of methyl isobutyrate relative to the total mass of the resin composition is preferably 5 ppm by mass or more, more preferably 10 ppm by mass or more, even more preferably 15 ppm by mass or more, particularly preferably 30 ppm by mass or more, most preferably 40 ppm by mass or more, and also preferably 20,000 ppm by mass or less, more preferably 5,000 ppm by mass or less, even more preferably 1,000 ppm by mass or less, particularly preferably 500 ppm by mass or less. Down Most preferably, 100 ppm by mass or less. Down That is the case.

[0079] The above preferred upper and lower limits can be combined in any way. Specifically, preferred ranges for the methyl isobutyrate content relative to the total mass of the resin composition according to this embodiment include 5 ppm to 20,000 ppm by mass, 10 ppm to 5,000 ppm by mass, 15 ppm to 1,000 ppm by mass, 30 ppm to 500 ppm by mass, and 40 ppm to 100 ppm by mass.

[0080] <3-4. Properties of the resin composition> The resin composition according to this embodiment contains the methacrylic polymer (P), an α-olefin, and at least one compound selected in a specific amount from the group consisting of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate, and therefore exhibits excellent photostability.

[0081] Specifically, when a test piece made of a resin composition (square shape, 50 mm long x 50 mm wide, 3 mm thick) is subjected to the UV exposure test described below, the yellowness (YI) of the test piece, measured in accordance with ASTM D1925, obtained from before the start of the UV exposure test to 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, even more preferably 5.5 or less, even more preferably 5.0 or less, and particularly preferably 4.8 or less.

[0082] <4. Resin molded product> A resin molded article (also simply referred to as "resin molded article") according to the fourth embodiment of the present invention is a resin molded article containing the resin composition according to the third embodiment of the present invention. That is, the resin molded article according to this embodiment contains the resin composition according to the third embodiment of the present invention. By going through a molding process to mold the resin composition, a resin molded article having excellent photostability can be obtained while maintaining the transparency and heat resistance inherent in the methacrylic resin. Examples of molding methods in the molding process include press molding, injection molding, gas-assisted injection molding, welding molding, extrusion molding, blow molding, film molding, hollow molding, multilayer molding, melt spinning, etc. In this specification, the term "resin molded article" is not particularly limited as long as it contains the above-mentioned resin composition, and a molded article consisting only of the resin composition is substantially equivalent to either the resin composition or the resin molded article.

[0083] The shape of the resin molded body is not limited to the following, but examples include granular pellets, plate-shaped resin molded bodies (resin plates), or sheet or film-shaped resin molded bodies (resin sheets). The thickness of the resin molded body can be adjusted to any thickness as needed, from thick plates to thin films. For example, the thickness can be 0.1 μm to 30 mm or 1 mm to 30 mm.

[0084] The resin molded article has excellent photostability because it contains the resin composition described above. Specifically, the resin molded article exhibits excellent photostability such that the yellowness (YI) measured in accordance with ASTM D1925, obtained from before the start of the UV exposure test to 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, even more preferably 4.5 or less, and particularly preferably 4.0 or less.

[0085] <5. Method for manufacturing resin compositions or resin molded articles> There are no particular limitations on the method for producing a resin composition or a resin molded article containing the resin composition (hereinafter, the resin composition and the resin molded article are collectively referred to as "resin composition, etc."). Specific methods for producing resin composition, etc. include, for example, a method that includes a radical polymerization step of a polymerizable composition (X2) comprising a polymerizable composition (X2) according to a second embodiment of the present invention, preferably a monomer composition according to a first embodiment of the present invention. The radical polymerization step may include a syrup preparation step of polymerizing a portion of the polymerizable composition (X2) to prepare a syrup, and a polymerization step of polymerizing the polymerizable components in the syrup. In the syrup preparation step, "polymerizing a portion of the polymerizable composition (X2)" means polymerizing so that the content of the methacrylic polymer in the resulting syrup is 10% by mass or more and 80% by mass or less, preferably 10% by mass or more and 60% by mass or less, and more preferably 10% by mass or more and 40% by mass or less.

[0086] The polymerization temperature when polymerizing the polymerizable composition (X2) is not particularly limited and can be appropriately determined by those skilled in the art in accordance with well-known techniques. Typically, it is appropriately set in a range of preferably 40°C to 180°C, more preferably 50°C to 150°C, depending on the type of radical polymerization initiator used. Furthermore, the polymerizable composition (X2) can be polymerized under multiple temperature conditions as needed. The polymerization time can be appropriately determined according to the progress of polymerization curing.

[0087] Examples of polymerization methods for the polymerizable composition (X2) include bulk polymerization, suspension polymerization, emulsion polymerization, or dispersion polymerization. Among these, bulk polymerization is preferred in terms of productivity.

[0088] Furthermore, specific methods for producing resin compositions include, for example, obtaining resin compositions by bulk polymerization using known cast polymerization methods such as the cell-cast method or the continuous-cast method, or obtaining resin compositions by molding a composition produced by bulk polymerization. From the viewpoint of further improving the heat resistance of the resin composition by increasing the molecular weight and introducing cross-linked structures, it is more preferable to employ a method using cast polymerization (injection polymerization).

[0089] As an example of a cast polymerization method, when obtaining a resin composition having a plate-like form, a cell cast method is used in which a space formed by two opposing glass plates or metal plates (SUS plates) and gaskets such as flexible resin tubes placed on their edges is used as a mold, a polymerizable composition (X2) or syrup polymerized with respect to a portion of the polymerizable composition (X2) is injected into the mold, polymerization is completed by heat polymerization treatment, and the resin composition is removed from the mold. Alternatively, a continuous cast method is used in which a space formed by two stainless steel endless belts traveling opposite each other in the same direction at the same speed with a predetermined distance between them and gaskets such as flexible resin tubes placed on both sides of the endless belts is used as a mold, a polymerizable composition (X2) or syrup polymerized with respect to a portion of the polymerizable composition (X2) is continuously injected into the mold from one end of the endless belts, polymerization is completed by heat polymerization treatment, and the resin composition is continuously removed from the other end of the endless belts. By appropriately adjusting the spacing of the voids in the mold using the gasket thickness (diameter), a resin composition of the desired thickness can be obtained. The thickness of the plate-shaped resin composition is usually set within the range of 1 mm to 30 mm.

[0090] <6.Applications> The uses of the above-mentioned resin composition and resin molded articles ("resin composition, etc.") are not particularly limited, but they are preferably used as translucent members, especially transparent members, for use in vehicle components, medical components, toys, liquid containers, optical materials, signs, displays, decorative components, building components, or panels for electronic equipment. [Examples]

[0091] The features of the present invention will be further described below with reference to examples and reference examples. The materials, amounts used, proportions, processing content, processing procedures, etc., shown in the following examples can be modified as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be interpreted as being limited by the specific examples shown below. In addition, in the following, "parts" refers to "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.) Furthermore, the methyl methacrylate (manufactured by Mitsubishi Chemical Corporation) contained 260 ppm by mass of methyl isobutyrate, 8 ppm by mass of methyl propionate, 19 ppm by mass of methyl pyruvate, and 8 ppm by mass of methyl 2-methylbutyrate, relative to the total mass of methyl methacrylate.

[0093] [Measurement Methods and Evaluation Methods] <Method for determining the content of at least one compound selected from the group consisting of transition metal compounds and group 13 element compounds in a monomeric composition> Two g of monomeric composition was accurately weighed and placed in a Kjeldahl decomposition flask. Three mL of sulfuric acid was added, and the mixture was completely carbonized in a Kjeldahl decomposition apparatus and then cooled. Two mL of sulfuric acid was then added, heated, cooled, and three mL of nitric acid was added to decompose it again. This series of operations was repeated three times. After cooling, 3 mL of nitric acid and 1 mL of hydrogen peroxide were added, and the mixture was heated and then cooled again. This procedure was repeated until the color disappeared. After heating the nitric acid and hydrogen peroxide in the Kjeldahl flask to evaporate them, sulfuric acid was added to the Kjeldahl flask until the sulfuric acid content reached 5 mL, and the solution was prepared. The entire volume of this solution was transferred to a 100 mL volumetric flask and diluted with ultrapure water. The elements of this solution were quantified using an ICP emission spectrometer under the following conditions.

[0094] Equipment used: ICP emission spectrometer (PerkinElmer, model: Optima 8300) Output: 1300W Pump speed: 1.0 mL / min Plasma gas flow rate: 10 L / min Auxiliary gas flow rate: 0.2 L / min Nebulizer gas flow rate: 0.55 L / min Detector: SCD (Segmented Array CCD) Integration time: Auto (1~5sec) Number of measurements: 3 Measurement method: Absolute calibration curve method Chrome orientation: Axial

[0095] <Method for measuring the remaining amount of target substance in a resin composition> (1) Procedure for preparing samples and test solutions The resin molded bodies obtained in the examples and reference examples were finely crushed, and 0.2 g of the crushed resin was dissolved in 10 mL of acetone for residual pesticide testing (hereinafter simply referred to as "acetone"). After the resin was dissolved, 1 mL of the internal standard solution was added using a volumetric pipette. A 0.1 vol% methyl salicylate / acetone solution was used as the internal standard solution. Three different concentrations of test solutions were prepared by diluting the target standard reagent with acetone, and a three-level calibration curve was created by gas chromatography-mass spectrometry (GC / MS) measurement described later, and the content of each target substance in the sample was quantified. A 0.1 vol% methyl salicylate / acetone solution was used as the internal standard solution.

[0096] (GC / MS measurement conditions) Equipment: GC HP6890 / MS HP5973 (manufactured by Agilent) Ionization method: EI (Electron Ionization) method Column: DB-WAX 60m x 250μm x 0.5μm (manufactured by Agilent) Heating conditions: 70°C (5 min) → 200°C (5 min) Rate = 10°C / min Inlet temperature: 220°C AUX temperature: 230℃ Ion source temperature: 230℃ Split ratio: 10:1 Flow rate: 2.0mL / min Average linear velocity: 37cm / sec Injection volume: 1μL Measurement mode: SIM

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

[0098] [Photostable evaluation] The change in yellowness (ΔYI) was used as an indicator of the photostability of the resin compositions produced in the examples and reference examples.

[0099] <Photostability Test> The photostability test was performed using a metal weather accelerated photostability tester (DW-R8PL-A, manufactured by Daipla Wintes Co., Ltd.) equipped with a metal halide lamp (MW-60W, manufactured by Daipla Wintes Co., Ltd., model: KF-1) and a light cut filter (KF-1, manufactured by Daipla Wintes Co., Ltd.). Specifically, a test piece made of resin composition (50mm x 50mm square, 3mm thick) was placed in the evaluation chamber of the metal weather accelerated photostability tester, and light was irradiated onto the test piece from the metal halide lamp for 300 hours. The UV irradiation intensity was measured at a wavelength of 300-400nm using an ultraviolet irradiometer (UVP-365-03, manufactured by Ushio Inc.), and the irradiation intensity was 130mW / cm². 2 The values ​​were corrected accordingly. The test specimens were irradiated with visible light and UV light from a metal halide lamp. The evaluation chamber of the metal weather accelerated photostability tester was set to an environment of 63°C and 50 RH.

[0100] <Manufacturing of resin compositions> [Example 1] (1) Manufacturing of syrup In a reactor (polymerization vessel) equipped with a condenser, thermometer, and stirrer, 1-octene and methyl propionate, both α-olefins, were added, followed by the supply of methyl methacrylate. After bubbling with nitrogen gas while stirring, heating was started. When the internal temperature of the reactor reached 80°C, 0.12 parts of 2,2'-azobis-(2,4-dimethylvaleronitrile) as a radical polymerization initiator and 0.075 parts of 1-dodecanethiol as a chain transfer agent were added. The reactor was then heated further until the internal temperature reached 100°C and held for 9 minutes. Subsequently, the reactor was cooled to room temperature to obtain a syrup containing 500 ppm each of 1-octene and at least one compound selected from the group consisting of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate. The polymer content in the syrup was 25% by mass relative to the total mass of the syrup.

[0101] (2) Cast polymerization To 100 parts of the above syrup, 0.15 parts of t-hexylperoxypivared as a radical polymerization initiator was added to obtain a polymerizable composition (X2). Next, the polymerizable composition (X2) was poured into a space with a gap of 6.5 mm, which was created by placing a soft resin gasket at the edge of the SUS plates between two opposing SUS plates. The polymerizable composition (X2) was cured by heating at 80°C for 30 minutes, and then at 130°C for 30 minutes, to obtain a resin composition. The composition of the resin composition is shown in Table 1. Next, the (meth)acrylic resin composition was cooled together with the SUS plates, and then the SUS plates were removed to obtain a plate-shaped resin molded body with a thickness of 5 mm. The evaluation results of the properties of the obtained resin molded body are shown in Table 1. In Table 1, "-" means that no measurement was performed.

[0102] [Examples 2-7, Reference Examples 1-6] Resin compositions and resin molded articles were produced in the same manner as in Example 1, except that the monomer composition was changed as shown in Tables 1 and 2. The composition of the obtained resin compositions is shown in Tables 1 and 2. The results of the property evaluation of the obtained resin molded articles are shown in Tables 1 and 2.

[0103] Examples 1 to 10 used monomeric compositions 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, wherein the total content of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate is greater than 36 ppm by mass relative to the total mass of the monomeric composition, and the monomeric composition used comprises at least one α-olefin selected from the group consisting of 2-ethyl-1-hexene, 1-octene, and 1-dodecene. The resin compositions obtained by polymerizing these monomer compositions were resin compositions 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, wherein the total content of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate was greater than 26 ppm by mass, and the α-olefin was at least one selected from the group consisting of 2-ethyl-1-hexene, 1-octene, and 1-dodecene. The resin molded articles obtained by molding these resin compositions were found to have excellent photostability while maintaining the transparency and heat resistance inherent in methacrylic resins.

[0104] On the other hand, although the monomer compositions of Reference Examples 1, 2, 4, and 5 contain α-olefins, the total content of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate is 36 ppm by mass or less. The monomer composition of Reference Example 3 does not contain α-olefins, and the total content of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate is also 36 ppm by mass or less. The monomer compositions of Reference Examples 6 and 7 contain a total content of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate exceeding 36 ppm by mass, but do not contain α-olefins. Furthermore, although the resin compositions of Reference Examples 1, 2, 4, and 5 contain α-olefins, the total content of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate is 26 ppm by mass or less. The monomer composition of Reference Example 3 does not contain α-olefins, and the total content of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate is also 26 ppm by mass or less. The monomer compositions of Reference Examples 6 and 7 contain a total amount of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate exceeding 36 ppm by mass, but do not contain α-olefins.

[0105] Comparing Examples 1-10 with Reference Example 3, it can be seen that the resin molded articles obtained in Examples 1-10 maintain performance equivalent to that of conventional resin molded articles made from methacrylic resin, including transparency and heat resistance. Since the transparency (YI at 0 hours of light irradiation) required for typical methacrylic resin molded articles is 0.5 or less, and the heat resistance (HDT) is 100°C or higher, it can be seen that the resin molded articles obtained in Examples 1 to 10 have transparency and heat resistance that exceed the levels required for typical methacrylic resin molded articles.

[0106] Furthermore, comparing Examples 1-10 with Reference Examples 1-7, it can be seen that the resin molded articles obtained in Examples 1-10 have significantly higher photostability than the molded articles obtained in Reference Examples 1-7.

[0107] Furthermore, Examples 1 to 10 show that, as long as the monomer composition and resin composition contain 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, a resin molded article with excellent transparency, heat resistance, and light stability can be obtained, regardless of the content.

[0108] Furthermore, in Example 10, the monomer composition and resin composition contain α-olefin and at least one compound selected from the group consisting of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate, and also contain two compounds selected from the group consisting of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate. From Example 10, it can be seen that if the total content of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate is above a certain amount, a resin molded article can be obtained that exhibits significantly higher photostability in addition to transparency and heat resistance equivalent to conventional methacrylic resin molded articles, regardless of which compound is selected.

[0109] [Table 1]

[0110] [Table 2]

Claims

1. A monomeric composition comprising methyl methacrylate, an α-olefin, and at least one compound selected from the group consisting of methyl pyruvate and methyl 2-methylbutyrate, The total content of methyl pyruvate and methyl 2-methylbutyrate is greater than 36 ppm by mass relative to the total mass of the monomer composition. A monomeric composition wherein the α-olefin comprises 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% by mass or more with respect to the total mass of the monomer composition.

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

4. The monomer composition according to claim 1, wherein the content of the α-olefin is 0.1 ppm by mass or more with respect to the total mass of the monomer composition.

5. The monomer composition according to claim 1, wherein the content of the α-olefin is 10 ppm by mass or more with respect to the total mass of the monomer composition.

6. The monomer composition according to claim 1, wherein the content of the α-olefin is 60 ppm by mass or more with respect to the total mass of the monomer composition.

7. The monomer composition according to claim 1, wherein the content of the α-olefin is 80 ppm by mass or more with respect to the total mass of the monomer composition.

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

9. The monomer composition according to claim 1, wherein the total content of methyl pyruvate and methyl 2-methylbutyrate is 40 ppm by mass or more based on the total mass of the monomer composition.

10. The monomer composition according to claim 1, wherein the total content of methyl pyruvate and methyl 2-methylbutyrate is 60 ppm by mass or more based on the total mass of the monomer composition.

11. The monomer composition according to claim 1, wherein the total content of methyl pyruvate and methyl 2-methylbutyrate is 70 ppm by mass or more, relative to the total mass of the monomer composition.

12. The monomer composition according to claim 1, wherein the total content of methyl pyruvate and methyl 2-methylbutyrate is 100 ppm by mass or more, relative to the total mass of the monomer composition.

13. The monomer composition according to claim 1, wherein the ratio of the content of the α-olefin to the total content of methyl pyruvate and methyl 2-methylbutyrate ([mass of the α-olefin] / [total mass of methyl pyruvate and methyl 2-methylbutyrate]) is 0.00001 or more and 1,000 or less.

14. The monomer composition according to claim 1, further containing an acrylic acid ester.

15. The monomer composition according to claim 14, wherein the acrylic acid ester 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 acrylic acid ester is methyl acrylate or ethyl acrylate.

17. The monomer composition according to claim 1, further containing styrene.

18. The monomer composition according to claim 1, further containing methyl isobutyrate.

19. A method for producing a resin composition, comprising a radical polymerization step of radically polymerizing a polymerizable composition containing the monomer composition described in any one of claims 1 to 18.

20. A resin composition comprising a polymer of the monomer composition described in any one of claims 1 to 18.

21. A resin composition comprising a methacrylic polymer (P), an α-olefin, and at least one compound selected from the group consisting of methyl pyruvate and methyl 2-methylbutyrate, The total content of methyl pyruvate and methyl 2-methylbutyrate is greater than 26 ppm by mass relative to the total mass of the resin composition. A resin composition wherein the α-olefin comprises 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% by mass or more of repeating units derived from methyl methacrylate, based on the total mass of the methacrylic polymer (P).

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

24. The resin composition according to claim 21, wherein the content of the α-olefin is 0.1 ppm by mass or more with respect to the total mass of the resin composition.

25. The resin composition according to claim 21, wherein the content of the α-olefin is 10 ppm by mass or more with respect to the total mass of the resin composition.

26. The resin composition according to claim 21, wherein the content of the α-olefin is 60 ppm by mass or more with respect to the total mass of the resin composition.

27. The resin composition according to claim 21, wherein the content of the α-olefin is 80 ppm by mass or more with respect to the total mass of the resin composition.

28. The resin composition according to claim 21, wherein the total content of methyl pyruvate and methyl 2-methylbutyrate is 30 ppm by mass or more with respect to the total mass of the resin composition.

29. The resin composition according to claim 21, wherein the total content of methyl pyruvate and methyl 2-methylbutyrate is 40 ppm by mass or more with respect to the total mass of the resin composition.

30. The resin composition according to claim 21, wherein the total content of methyl pyruvate and methyl 2-methylbutyrate is 60 ppm by mass or more with respect to the total mass of the resin composition.

31. The resin composition according to claim 21, wherein the total content of methyl pyruvate and methyl 2-methylbutyrate is 80 ppm by mass or more with respect to the total mass of the resin composition.

32. The resin composition according to claim 21, further comprising methyl isobutyrate in the resin composition.

33. The resin composition according to claim 21, wherein the methacrylic polymer (P) comprises repeating units derived from methyl methacrylate and repeating units derived from acrylic acid ester.

34. The resin composition according to claim 21, wherein the methacrylic polymer (P) comprises 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 claims 21 to 34.

36. A vehicle component comprising the resin molded body described in claim 35.

37. A medical component comprising the resin molded body described in claim 35.

38. A toy comprising a resin molded body as described in claim 35.

39. A liquid container comprising a resin molded body as described in claim 35.

40. An optical material comprising a resin molded article as described in claim 35.

41. A sign, comprising the resin molded body described in claim 35.

42. A display comprising a resin molded body as described in claim 35.

43. The process includes a molding step of molding a resin composition comprising a methacrylic polymer (P), an α-olefin, and at least one compound selected from the group consisting of methyl pyruvate and methyl 2-methylbutyrate. The total content of methyl pyruvate and methyl 2-methylbutyrate in the resin composition is greater than 26 ppm by mass relative to the total mass of the resin composition. A method for producing a resin molded article, wherein the α-olefin comprises at least one selected from the group consisting of 2-ethyl-1-hexene, 1-octene, and 1-dodecene.

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