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 methyl isobutyrate, in which the content of the methyl isobutyrate is greater than 260 ppm by mass with respect to the total mass of the monomer composition, and the alpha-olefin contains 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 properties, 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 having light transmittance.

[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 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 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 derived from the additives. Therefore, there is a problem that it cannot be used in cases where a specific hue and transparency are simultaneously required.

[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 in 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, α-olefin, and methyl isobutyrate, wherein, relative to the total mass of the monomer composition, the content of methyl isobutyrate is greater than 260 mass ppm, and 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 〔1〕, wherein, relative to the total mass of the monomer composition, the content of methyl methacrylate is 85 mass% or more. 〔3〕 The monomer composition according to 〔1〕 or 〔2〕, wherein, relative to the total mass of the monomer composition, the content of methyl methacrylate is 90 mass% or more. 〔4〕 The monomer composition according to any one of 〔1〕 to 〔3〕, wherein, relative to the total mass of the monomer composition, the content of the α-olefin is 0.1 mass ppm or more. 〔5〕 The monomer composition according to any one of 〔1〕 to 〔4〕, wherein, relative to the total mass of the monomer composition, the content of the α-olefin is 10 mass ppm or more. 〔6〕 The monomer composition according to any one of 〔1〕 to 〔5〕, wherein, relative to the total mass of the monomer composition, the content of the α-olefin is 60 mass ppm or more. 〔7〕 The monomer composition according to any one of 〔1〕 to 〔6〕, wherein, relative to the total mass of the monomer composition, the content of the α-olefin is 80 mass ppm or more. 〔8〕 The monomer composition according to any one of 〔1〕 to 〔7〕, wherein, relative to the total mass of the α-olefin, 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. 〔9〕 The monomer composition according to any one of 〔1〕 to 〔8〕, wherein, relative to the total mass of the monomer composition, the content of methyl isobutyrate is 270 mass ppm or more. 〔10〕 The monomer composition according to any one of [1] to [9], wherein the content of methyl isobutyrate is 280 mass ppm 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 content of methyl isobutyrate is 290 mass ppm 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 content of methyl isobutyrate is 450 mass ppm or more based on 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 content of methyl isobutyrate ([mass of the α-olefin] / [mass of methyl isobutyrate]) 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 at least one compound selected from the group consisting of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate.

[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 according to any one of [1] to

[18] .

[21] A resin composition, characterized by containing: a methacrylic polymer (P), an α-olefin, and methyl isobutyrate, The content of methyl isobutyrate is greater than 49 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. 〔22〕 The resin composition according to 〔21〕, wherein the methacrylic polymer (P) contains 50% by 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 〔21〕 or 〔22〕, wherein the methacrylic polymer (P) contains 70% by 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 〔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 〔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 〔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 〔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 〔21〕 to 〔27〕, wherein the content of methyl isobutyrate is 60 mass ppm or more relative to the total mass of the resin composition. 〔29〕 The resin composition according to any one of 〔21〕 to 〔28〕, wherein the content of methyl isobutyrate is 80 mass ppm or more relative to the total mass of the resin composition. 〔30〕 The resin composition according to any one of 〔21〕 to 〔29〕, wherein the content of methyl isobutyrate is 100 mass ppm or more relative to the total mass of the resin composition. 〔31〕 The resin composition according to any one of

[21] to

[30] , wherein the content of methyl isobutyrate is 200 mass ppm or more relative to the total mass of the resin composition.

[32] The resin composition according to any one of

[21] to

[31] , further comprising at least one compound selected from the group consisting of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate.

[33] 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 an acrylate.

[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 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 article, wherein the manufacturing method includes a molding step of molding a resin composition containing a methacrylic polymer (P), an α-olefin, and methyl isobutyrate, the content of methyl isobutyrate in the resin composition is greater than 49 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. Advantages of the Invention

[0010] According to the present invention, 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 can be provided, which are used to obtain a resin composition that maintains the transparency and heat resistance inherent in a methacrylic resin and has excellent light stability. Detailed Description of the Invention

[0011] The definitions of the following terms in this specification and 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 in which a part of the unit is transformed 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" means that conjugation does not occur. "The obtained resin composition" refers to a resin composition obtained by subjecting a monomer mixture containing a monomer composition to radical polymerization. "The obtained resin molded article" refers to a resin molded article 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 ray" refer to light mainly including 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 of Elements”, [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 indicated 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, α-olefin, and methyl isobutyrate. With respect to the total mass of the monomer composition, the content of methyl isobutyrate is greater than 260 mass ppm. The α-olefin includes 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 not impairing the effects of the present invention, other components may also be contained.

[0015] <1-1. Methyl methacrylate> The monomer composition of the present 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 polymerized from a monomer composition containing methyl methacrylate can also be used. Methyl methacrylate is more preferably methyl methacrylate obtained by thermally decomposing a resin composition polymerized from a monomer composition containing methyl methacrylate. By containing methyl methacrylate, the monomer composition of the present embodiment can provide a resin composition ensuring excellent light stability and the inherent heat resistance of the methacrylic resin.

[0016] The lower limit of the content of methyl methacrylate relative 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, still more 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, α-olefin, and methyl isobutyrate relative to the total mass of the monomer composition of the present embodiment is not particularly limited, and is usually 100% by mass or less.

[0018] <1-2.α-olefin> By containing the following α-olefin, the monomer composition of the present embodiment, where the α-olefin contains at least one selected from the group consisting of 2-ethyl-1-hexene, 1-octene, and 1-dodecene, can provide a resin composition having excellent light stability. The α-olefin 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, and from the viewpoint of being able to provide a resin composition with good light stability, it is preferably 0.1 mass ppm or more, more preferably 10 mass ppm or more, still more 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 is not particularly limited with respect to the total mass of the monomer composition of the present embodiment. From the viewpoint of providing a resin composition that can well maintain heat resistance, 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 arbitrarily combined. Specifically, with respect to the total mass of the monomer composition of the present embodiment, the content of 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 two or more α-olefins.

[0022] It is speculated that the coupling product of the α-olefins with attached free radicals generated by ultraviolet rays is stable, and the free radical scavenging effect is excellent.

[0023] 2-Ethyl-1-hexene, 1-octene, and 1-dodecene do not volatilize due to heating during polymerization and are easily retained in the obtained resin composition. Therefore, it can sufficiently contribute to improving the light stability of the resin composition obtained by polymerization of 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 at a lower 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 more 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 from the viewpoint of being easily retained in the resin composition after polymerization. The ratio of 1-octene in the α-olefin is not particularly limited with respect to the total mass of the α-olefin, preferably 50 mass% or more, more preferably 80 mass% or more, and usually 100 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.

[0026] In the present embodiment, compared with methyl methacrylate as a conjugated monomer, the α-olefin cannot obtain a resonance stabilization effect and the reactivity is significantly low. 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, unless it is a special condition for exerting the effect as a catalyst, unreacted α-olefin (hereinafter also referred to as "α-olefin monomer") remains in the obtained resin composition. It is considered that a resin composition with good light stability can be provided by the α-olefin monomer remaining in the resin composition. That is, in order for the at least one compound not to exert the effect as 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 the type of the at least one compound, for example, a compound of a transition metal of Group 5 to Group 11 having a chelating ligand or a Lewis acid catalyst can be cited. As specific examples of the transition metal, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, manganese, iron, platinum, ruthenium, cobalt, rhodium, nickel, palladium, and copper can be cited. Among these transition metals, preferably, transition metals of Group 8 to Group 11 are used, more preferably, transition metals of Group 10 are used, and further preferably, nickel (Ni) or palladium (Pd) is used. These transition metals can be used alone or in combination of two or more.

[0028] The above chelating ligand has at least two 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 structures of chelating ligands are 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, bidentate anionic P, O ligands can be cited. As the bidentate anionic P, O ligands, for example, phosphosulfonic acid, phosphocarboxylic acid, phosphophenol, and phosphoenol can be cited. As chelating ligands other than the bidentate anionic P, O ligands, for example, bidentate anionic N, O ligands can be cited. As the bidentate anionic N, O ligands, for example, salicylaldimine and pyridinecarboxylic acid can be cited. As chelating ligands other than the bidentate anionic P, O ligands and the bidentate anionic N, O ligands, for example, diimine ligands, diphenoxide ligands, and diamide ligands can be cited.

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

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

[0031] <1-3. Methyl isobutyrate> Methyl isobutyrate is one of the components contained in the monomer composition of the present embodiment. By making the content of methyl isobutyrate greater than 260 mass ppm with respect to the total mass of the monomer composition, a resin composition having excellent light stability can be provided.

[0032] Based on the total mass of the monomer composition of the present embodiment, starting from the perspective of being able to provide a resin composition with good light stability, the lower limit of the content of methyl isobutyrate is generally greater than 260 mass ppm, preferably 270 mass ppm or more, more preferably 280 mass ppm or more, further preferably 290 mass ppm or more, further more preferably 450 mass ppm or more, and particularly preferably 500 mass ppm or more.

[0033] Based on the total mass of the monomer composition of the present embodiment, the upper limit of the content of methyl isobutyrate is not particularly limited. Starting from the perspective of being able to provide a resin composition that can maintain heat resistance well, 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, further more preferably 5,000 mass ppm or less, and particularly preferably 3,000 mass ppm or less.

[0034] The above-mentioned preferred upper and lower limit values can be combined arbitrarily. Specifically, based on the total mass of the monomer composition of the present embodiment, the content of methyl isobutyrate is preferably greater than 260 mass ppm and 20,000 mass ppm or less, more preferably 270 mass ppm or more and 20,000 mass ppm or less, further preferably 280 mass ppm or more and 15,000 mass ppm or less, further more preferably 290 mass ppm or more and 10,000 mass ppm or less, particularly preferably 450 mass ppm or more and 5,000 mass ppm or less, and most preferably 500 mass ppm or more and 3,000 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 content of methyl isobutyrate (also referred to as "[mass of α-olefin] / [mass of methyl isobutyrate] ratio") is not particularly limited. Due to the interaction between methyl isobutyrate and α-olefin, from the perspective of being able to provide a resin molded body with good light stability, it is preferably 1,000 or less, more preferably 500 or less, further preferably 300 or less, further more preferably 100 or less, particularly preferably 10 or less, and most preferably 5 or less. The lower limit of the [mass of α-olefin] / [mass of methyl isobutyrate] ratio is not particularly limited. From the perspective of the heat resistance of the resin molded body becoming good, it is preferably 0.00001 or more, more preferably 0.0001 or more, further preferably 0.001 or more, further more preferably 0.01 or more, particularly preferably 0.1 or more, and most preferably 0.2 or more.

[0036] The above upper limit value and lower limit value can be arbitrarily combined. For example, as the preferred range of the ratio of [mass of α-olefin] / [mass of methyl isobutyrate], the following can be cited: 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, 0.1 or more and 10 or less, and 0.2 or more and 5 or less. Among these, the ratio of [mass of α-olefin] / [mass of methyl isobutyrate] is more preferably 0.0001 or more and 500 or less, and even more preferably 0.001 or more and 300 or less.

[0037] <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 two or more can be used in any ratio and combination. (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-phenyl maleimide or N-cyclohexyl maleimide. (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 monomer having two or more ethylenically unsaturated bonds in the molecule: For example, divinylbenzene. (15) Unsaturated polyester prepolymer obtained from at least one polycarboxylic acid containing ethylenically unsaturated polycarboxylic acid and at least one diol. (16) Vinyl ester prepolymer obtained by acrylate-modifying the terminal of an epoxy group.

[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, and more preferably methyl acrylate or ethyl acrylate. Further, the content of the acrylate is preferably 0% by mass or more and 30% by mass or less with respect to the total mass of the monomer composition. By containing an acrylate in the monomer composition, a resin composition having excellent light stability can be provided. In addition, it is possible to suppress a decrease in light stability when a resin molded body containing the resin composition is exposed to light for a long time. 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. At least one compound selected from the group consisting of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate> The above monomer composition preferably further contains at least one compound selected from the group consisting of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate. By containing this compound, a resin composition with further excellent light stability can be provided. In addition, it is possible to suppress a decrease in light stability when a resin molded body containing this resin composition is exposed to light for a long time.

[0040] When the monomer composition of the present embodiment contains at least one compound selected from the group consisting of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate, the total content of methyl isobutyrate, methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate is preferably an amount within the range of the content of the above-mentioned methyl isobutyrate with respect to the total mass of the monomer composition.

[0041] In addition, when the monomer composition of the present embodiment contains 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 preferably 5 mass ppm or more, more preferably 10 mass ppm or more, further preferably 15 mass ppm or more, particularly preferably 20 ppm or more, most preferably 25 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 less, most preferably 100 mass ppm or less. It is preferably an amount within the range of the content of the above-mentioned methyl isobutyrate.

[0042] The above-mentioned preferred upper and lower limit values can be arbitrarily combined. Specifically, with respect to the total mass of the monomer composition of the present embodiment, as the preferred range of the total content of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate, there can be mentioned ranges of 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, 20 mass ppm or more and 500 mass ppm or less, and 25 mass ppm or more and 100 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 mold release agents, heat stabilizers, flow aids, plasticizers, antioxidants, antistatic agents, light stabilizers other than α-olefins and methyl isobutyrate, ultraviolet absorbers, flame retardants, flame retardant aids, fillers, pigments, dyes, silane coupling agents, leveling agents, defoaming agents, and fluorescent agents. These additives can be used alone or in combination of any two or more in any ratio and combination.

[0044] In this embodiment, α-olefin and methyl isobutyrate are considered to exhibit excellent light stability through a mechanism different from that of commonly known UV absorbers and radical scavengers (HALS). Therefore, α-olefin and methyl isobutyrate can also be used in combination with additives such as UV absorbers and HALS. By including α-olefin, methyl isobutyrate, and such additives in the monomer composition, a resin composition and a resin molded article with further increased light stability can be provided.

[0045] In addition, the monomer composition of this 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 one form of the raw material for obtaining the resin composition of the third embodiment of the present invention described later. The polymerizable composition of this embodiment (also referred to as "polymerizable composition (X2)") is a polymerizable composition containing the monomer composition and a known radical polymerization initiator 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. Additives> The form of the additives is the same as that described in <1-6. Additives>. It should be noted that the additives 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 methyl isobutyrate. Among them, relative to the total mass of the resin composition, the content of methyl isobutyrate is greater than 49 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. 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 may be 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 a specific content of methyl isobutyrate, the following resin molded body can be provided. In the polymer chain of the methacrylic polymer (P), the α-olefin and methyl isobutyrate exist in a monomer state, and even when exposed to UV for a long time, yellowing can be suppressed, and further reduction in light stability can be suppressed. In addition, the form of the resin composition is not particularly limited and is usually solid. The form of methyl isobutyrate is the same as that described in <1-3. Methyl isobutyrate>. 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 following ranges can be mentioned: 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. 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, the content of the α-olefin 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, still further preferably 90 mass ppm or more, and particularly preferably 100 mass ppm or more.

[0054] The upper limit of the content of the α-olefin is not particularly defined with respect to the total mass of the resin composition. 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, still further preferably 2,000 mass ppm or less, and particularly preferably 1,000 mass ppm or less.

[0055] The above upper limit value and lower limit value can be combined arbitrarily. For example, 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, 90 mass ppm or more and 2,000 mass ppm or less, and 100 mass ppm or more and 1,000 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, from the viewpoint of obtaining excellent light stability, the lower limit of the content of methyl isobutyrate is usually greater than 49 mass ppm, preferably 50 mass ppm or more, more preferably 60 mass ppm or more, further preferably 80 mass ppm or more, particularly preferably 100 mass ppm or more, and most preferably 200 mass ppm or more.

[0057] With respect to the total mass of the resin composition, the upper limit of the content of methyl isobutyrate 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 combined arbitrarily. For example, as the preferred content of methyl isobutyrate, the following ranges can be cited: greater than 49 mass ppm and 20,000 mass ppm or less, 50 mass ppm or more and 20,000 mass ppm or less, 60 mass ppm or more and 15,000 mass ppm or less, 80 mass ppm or more and 10,000 mass ppm or less, 100 mass ppm or more and 5,000 mass ppm or less, and 200 mass ppm or more and 3,000 mass ppm or less. Among these, the content of methyl isobutyrate is more preferably 10 mass ppm or more and 20,000 mass ppm or less, and further preferably 30 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 a specific content of methyl isobutyrate. The resin composition obtained by free-radical polymerization of the polymerizable composition (X2) containing the monomer composition has excellent heat resistance, excellent light stability, and suppressed yellowing. By containing an α-olefin and a specific content of methyl isobutyrate, the monomer composition of the first embodiment of the present invention can obtain a resin composition that has excellent heat resistance, excellent light stability, and suppressed yellowing. The reason is presumed 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 the specific content of methyl isobutyrate contained in the monomer composition of the first embodiment of the present invention cannot obtain a resonance stabilization effect and have significantly lower reactivity compared to methyl methacrylate as a conjugated monomer. Therefore, as long as under normal conditions, in the obtained resin composition, unreacted α-olefin (also referred to as α-olefin monomer) and unreacted methyl isobutyrate (also referred to as methyl isobutyrate monomer) remain. Moreover, it is considered that the unreacted α-olefin and methyl isobutyrate 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 whose hydrogen atom has been abstracted interacts with the unreacted methyl isobutyrate to replace the hydrogen atom, so that the α-olefin acts 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 the α-olefin and methyl isobutyrate alone, but also the synergistic effect obtained by using the α-olefin and methyl isobutyrate together, 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 content of methyl isobutyrate (also referred to as "[mass of α-olefin] / [mass of methyl isobutyrate] ratio") is not particularly limited. From the perspective of improving the light stability of the resin molded body due to the interaction between methyl isobutyrate and the α-olefin, it is preferably 1,000 or less, more preferably 500 or less, further preferably 300 or less, further more preferably 100 or less, particularly preferably 10 or less, and most preferably 5 or less. The lower limit of the "[mass of α-olefin] / [mass of methyl isobutyrate] ratio" is not particularly limited. From the perspective of improving the heat resistance of the resin molded body, it is preferably 0.00001 or more, more preferably 0.0001 or more, further preferably 0.001 or more, further more preferably 0.01 or more, particularly preferably 0.05 or more, and most particularly preferably 0.1 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] / [mass of methyl isobutyrate] ratio", the following can be cited: a range 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, 0.05 or more and 10 or less, and 0.1 or more and 5 or less. Among these, the "[mass of α-olefin] / [mass of methyl isobutyrate] 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. By containing the methacrylic polymer (P), the resin composition can improve transparency while suppressing decomposition caused by heat or light, and make the heat formability, heat resistance, and mechanical strength good. Further, due to the synergistic effect of the heat resistance originally possessed by the methacrylic polymer (P) with the α-olefin and a specific content of methyl isobutyrate, a methacrylic resin molded body with high light stability and maintained 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 improving 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 (hereinafter also referred to as "acrylate units") from acrylates or styrene units as required. 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 from acrylates, they are repeating units from acrylates 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 two or more of them can be used in any ratio and combination. Among these monomers, from the perspective of ensuring high light stability, the resin molded body of 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 improving 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.

[0070] The content ratio of acrylate units in the methacrylic 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 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 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, further more 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 where the inventive effects are achieved, the methacrylic 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 group, allyl group, (meth)acryloyl group, (meth)acryloyloxy group, etc. In particular, the (meth)acryloyl group is preferred from the viewpoints of excellent storage stability of the compound 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 the monomer having two radically polymerizable functional groups may be the same or different. By containing polyfunctional monomer units, the methacrylic polymer (P) can improve solvent resistance, chemical resistance, etc.

[0073] Examples of the polyfunctional monomer 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 may be used alone or two or more of them may be used in combination at any ratio. Among these, from the viewpoint 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 article, etc. For example, it may be 10,000 or more, it may be 100,000 or more, it may be 150,000 or more, and may be 1,000,000 or less, may be 2,000,000 or less, and may also be 4,000,000 or less. By appropriately increasing the weight-average molecular weight, 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] <3-3. At least one compound selected from the group consisting of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate> It is also preferable that the above resin composition contains at least one compound selected from the group consisting of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate. By containing this compound, a resin composition having further excellent light stability is obtained, and 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.

[0077] When the resin composition of the present embodiment contains at least one compound selected from the group consisting of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate, the total content of methyl isobutyrate, methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate is preferably an amount within the range of the content of methyl isobutyrate described above with respect to the total mass of the resin composition.

[0078] In addition, when the resin composition of the present embodiment contains 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 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 60 mass ppm or more, and 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 more, most preferably 3,000 mass ppm or more with respect to the total mass of the resin composition.

[0079] The above preferable upper limit value and lower limit value can be arbitrarily combined. Specifically, as the preferable range of the total content of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate with respect to the total mass of the resin composition of the present embodiment, there can be mentioned ranges of 5 mass ppm or more and 20,000 mass ppm or less, 10 mass ppm or more and 15,000 mass ppm or less, 15 mass ppm or more and 10,000 mass ppm or less, 15 mass ppm or more and 10,000 mass ppm or less, 30 mass ppm or more and 5,000 mass ppm or less, and 60 mass ppm or more and 3,000 mass ppm or less.

[0080] <3-4. Characteristics of the resin composition> The resin composition of the present embodiment contains the above methacrylic polymer (P), α-olefin, and a specific amount of methyl isobutyrate, and thus has excellent light stability.

[0081] Specifically, when performing the following UV exposure test on 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 a resin composition, for the above 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 6.0 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.

[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 this embodiment contains the resin composition of the third embodiment of the present invention. By undergoing a molding process of molding this resin composition, the following resin molded article can be obtained, which retains the transparency and heat resistance originally possessed by the methacrylic resin and has excellent light stability. As the molding method in the molding process, for example, there can be mentioned: compression molding, injection molding, gas-assisted injection molding, deposition molding, extrusion molding, blow molding, film molding, hollow molding, multilayer molding, melt spinning, etc. In this specification, the resin molded article is not particularly limited as long as it is a molded article containing the above 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 article is not limited to the following. For example, there can be mentioned: granular pellets, plate-shaped resin molded articles (resin plates), sheet- or film-shaped resin molded articles (resin sheets). The thickness of the resin molded article can be adjusted to any thickness from thick plate-like to thin film-like as needed. 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 article contains the above resin composition, it has excellent light stability. That is, the resin molded article exhibits the following excellent light stability: 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 6.0 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 article> The method for producing the resin composition or the resin molded article containing the resin composition (hereinafter, the resin composition and the resin molded article may also be collectively referred to as "resin composition, etc.") is not particularly limited. As a specific production method of the resin composition, etc., for example, a method including the following radical polymerization step can be mentioned, in which 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, is subjected 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 manner that the content of the methacrylic 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] The polymerization temperature when polymerizing the polymerizable composition (X2) is not particularly limited, and those skilled in the art can appropriately determine it according to known techniques. Generally, depending on the type of the radical polymerization initiator used, it is preferably set appropriately in the range of 40°C or higher and 180°C or lower, more preferably 50°C or higher and 150°C or lower. 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 mentioned. Among these, from the perspective of productivity, the bulk polymerization method is preferred.

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

[0089] As a casting polymerization method, for example, the 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 the edge thereof is used as a mold. A polymerizable composition (X2) or a slurry obtained by polymerizing a part of the polymerizable composition (X2) is poured into the mold, and polymerization is completed by performing heat polymerization treatment, and the resin composition or the like is taken out from the mold. Alternatively, the continuous casting method can be cited. In this method, 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 at both side edges thereof is used as a mold. The polymerizable composition (X2) or a slurry obtained by polymerizing a part of the polymerizable composition (X2) is continuously poured into the mold from one end of the endless belt, and polymerization is completed by performing 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. Uses> The uses of the above resin composition and resin molded article (“resin composition or the like”) are not particularly limited, and it is preferably used as a translucent 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 will be 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 by 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 isobutyrate (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 methyl methacrylate (manufactured by Mitsubishi Chemical Corporation) contains 260 mass ppm of methyl isobutyrate, 8 mass ppm of methyl propionate, 19 mass ppm of methyl pyruvate, and 8 mass ppm of 2-methylbutyl methacrylate relative to the total mass of methyl methacrylate.

[0093] [Measurement methods and evaluation methods] <Method for measuring the content of at least one compound selected from the group consisting of compounds of transition metals and compounds of Group 13 elements in a 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, heat and cool it, add 3 mL of nitric acid for re-digestion, 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 to volatilize the nitric acid and hydrogen peroxide in the Kjeldahl flask, add sulfuric acid to make the sulfuric acid content in the Kjeldahl flask 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. Quantify each element in this solution using an ICP optical emission spectrometer under the following conditions.

[0094] Device used: ICP optical emission spectrometer (manufactured by PerkinElmer, model name: Optima8300) Output power: 1300 W Pump speed: 1.0 mL / minute Plasma gas flow rate: 10 L / minute Auxiliary gas flow rate: 0.2 L / minute Nebulizer gas flow rate: 0.55 L / minute Detector: SCD (segmented 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 measuring the residual amount of the target substance in the resin composition> (1) Operating steps for sample and test solution preparation The resin molded articles 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 simply referred to as "acetone"). After the resin was dissolved, 1 mL of an internal standard solution was added using a single-mark pipette. The internal standard solution used was 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, and a three-point calibration curve was made by gas chromatography-mass spectrometry (GC / MS) described below to quantify the content of each target substance in the sample. The internal standard solution used was 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 / minute Injection port temperature: 220 °C AUX temperature: 230 °C Ion source temperature: 230 °C Split ratio: 10:1 Flow rate: 2.0 mL / minute Average linear velocity: 37 cm / second Injection volume: 1 μL Measurement mode: SIM

[0097] ><Evaluation method of heat resistance> As an index of the heat resistance of the resin compositions obtained in the examples and reference examples, for the test pieces (length 127 mm × width 12.7 mm × thickness 3 mm) of the resin molded articles 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.

[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 made of a resin composition (a square shape with a length of 50 mm × a width of 50 mm and a thickness of 3 mm) was set, and the test piece was irradiated with light 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 The test piece was irradiated with visible light and UV using the metal halide lamp. The evaluation chamber of the Metal Weather super-accelerated light stability testing machine was set to an environment with a temperature of 63 °C and a humidity of 50 RH%.

[0100] <Manufacture of Resin Composition> [Example 1] (1) Manufacture of Slurry 1-Octene and methyl isobutyrate as α-olefins were added to a reactor (polymerization kettle) equipped with a condenser, a thermometer, and a stirrer, and methyl methacrylate was further supplied. While stirring, nitrogen was bubbled, 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 a slurry containing 500 ppm of 1-octene and methyl isobutyrate respectively. The content of the polymer in the slurry was 25% by mass based on the total mass of the slurry.

[0101] (2) Injection Molding Polymerization To 100 parts of the above-mentioned slurry, 0.15 part of tert-hexyl peroxypivalate 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 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. Next, 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 properties 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 Table 1, a resin composition and a resin molded body were produced in the same manner as in Example 1. The composition of the obtained resin composition is shown in Table 1. The evaluation results of the properties of the obtained resin molded body are shown in Table 1.

[0103] In Examples 1 to 7, a monomer composition containing methyl methacrylate, an α-olefin, and methyl isobutyrate was used, wherein the content of methyl isobutyrate was greater than 260 mass ppm relative to the total mass of the monomer composition, and the α-olefin included 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 methyl isobutyrate, wherein the content of methyl isobutyrate is greater than 49 mass ppm relative to the total mass of the resin composition, and the α-olefin includes at least one monomer selected from the group consisting of 2-ethyl-1-hexene, 1-octene, and 1-dodecene. As can be seen from Table 1, the resin molded body obtained by molding these resin compositions retains 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 α-olefins, the content of methyl isobutyrate is 260 mass ppm or less. The monomer composition of Reference Example 3 does not contain α-olefins, and the content of methyl isobutyrate is also 260 mass ppm or less. Although the monomer composition of Reference Example 6 contains methyl isobutyrate in an amount greater than 260 mass ppm, it does not contain α-olefins. In addition, although the resin compositions of Reference Examples 1, 2, 4, and 5 contain α-olefins, the content of methyl isobutyrate is 49 mass ppm or less. The monomer composition of Reference Example 3 does not contain α-olefins, and the content of methyl isobutyrate is also 49 mass ppm or less. Although the monomer composition of Reference Example 6 contains methyl isobutyrate in an amount greater than 49 mass ppm, it does not contain α-olefins.

[0105] When Examples 1 to 7 are compared with Reference Example 3, it can be seen that the resin molded articles obtained in Examples 1 to 7 maintain the same properties as those of the resin molded articles made of conventional methacrylic resins in terms of transparency and heat resistance. The transparency (YI at 0 hours of light irradiation) required for a typical 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 7 exceed the standards required for typical methacrylic resin molded articles.

[0106] Furthermore, when Examples 1 to 7 are compared with Reference Examples 1 to 6, it can be seen that the light stability of the resin molded articles obtained in Examples 1 to 7 is also significantly higher than that of the molded articles obtained in Reference Examples 1 to 6.

[0107] In addition, from Examples 2, 3, and 5, it can be seen that as long as the monomer composition and the resin composition contain a specific amount or more of methyl isobutyrate, regardless of its content, a resin molded article having excellent transparency, heat resistance, and light stability can be obtained. In addition, it can be seen that by containing 1-octene or 2-ethyl-1-hexene as an α-olefin in the monomer composition and the resin composition, the following resin molded article can be obtained. The resin molded article has the same transparency and heat resistance as those of the conventional methacrylic resin molded articles and also exhibits particularly high light stability.

[0108] [Table 1]

Claims

1. A monomer composition, characterized in that, Comprising: methyl methacrylate, α-olefin, and methyl isobutyrate, The content of methyl isobutyrate is greater than 260 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 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 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 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 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 content of methyl isobutyrate is 270 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 content of methyl isobutyrate is 280 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 content of methyl isobutyrate is 290 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 content of methyl isobutyrate is 450 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 α-olefin to the content of methyl isobutyrate, i.e., [mass of α-olefin] / [mass of methyl isobutyrate], 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 an 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 at least one compound selected from the group consisting of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate.

19. A method for manufacturing a resin composition, wherein, Including a radical polymerization step of radically polymerizing a polymerizable composition, the polymerizable composition containing the monomer composition according to any one of claims 1 to 18.

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

21. A resin composition, characterized in that, Comprising: methacrylic polymer P, α-olefin, and methyl isobutyrate, The content of methyl isobutyrate is greater than 49 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, Relative to the total mass of the methacrylic polymer P, the methacrylic polymer P contains 50 mass % or more of repeating units derived from methyl methacrylate.

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

24. The resin composition according to any one of claims 21 to 23, wherein, The content of 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 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 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 content of methyl isobutyrate is 60 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 content of methyl isobutyrate is 80 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 content of methyl isobutyrate is 100 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 content of methyl isobutyrate is 200 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, It further contains at least one compound selected from the group consisting of methyl propionate, methyl pyruvate, and methyl 2-methylbutyrate.

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 comprising the resin composition according to any one of claims 20 to 34.

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

37. A medical component, which comprises the resin molded body described in claim 35.

38. A toy, which comprises the resin molded body described in claim 35.

39. A liquid container, which comprises the resin molded body described in claim 35.

40. An optical material, which comprises the resin molded body described in claim 35.

41. A billboard, which comprises the resin molded body described in claim 35.

42. A display, which comprises the resin molded body described in claim 35.

43. A method for manufacturing a resin molded body, wherein, The manufacturing method includes a shaping step of shaping a resin composition containing a methacrylic polymer P, an α-olefin, and methyl isobutyrate. The content of methyl isobutyrate in the resin composition is greater than 49 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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