N-phenylmaleimide compound and copolymer obtained using the same

Abstract

To provide an N-phenylmaleimide compound that employs N-phenylmaleimide containing impurities at or below a specified level as at least one component in a comonomer, thereby enabling improved quality in the resulting copolymer and molded product.SOLUTION: An N-phenylmaleimide (PMI) compound contains 0.06 mass% or less of N-phenylmaleamic acid (PMA) and 0.01 mass% or less of 2-anilino-N-phenylsuccinimide (APSI).SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to an N-phenylmaleimide compound and a copolymer obtained using the same. More specifically, the present invention relates to an N-phenylmaleimide compound having a low content of compounds inevitably generated during the production of the maleimide compound, and a copolymer obtained by copolymerization using the N-phenylmaleimide compound as at least one component of the monomer.

Background Art

[0002] Maleimide compounds are compounds useful as raw materials for resins, raw materials for pharmaceuticals, agricultural chemicals, etc. In particular, they are widely used as one of the copolymerization components for improving the heat resistance of styrene resins such as ABS resin, AS resin, AB resin, ACS resin, AES resin, AAS resin, and polyvinyl chloride resin, polymethyl methacrylate resin, phenolic resin, etc. Among them, N-phenylmaleimide (hereinafter also referred to as PMI) is particularly widely used because of its excellent reactivity and heat resistance.

[0003] Regarding the production method of maleimide compounds, there are many conventionally known methods, such as a method obtained by subjecting maleic anhydride and primary amines to a dehydration reaction in one step (for example, Patent Documents 1 and 2), a method of generating maleamic acids from maleic anhydride and primary amines and obtaining them by the dehydration cyclization imidization reaction of these maleamic acids (for example, Patent Documents 3 to 6), a method obtained by the cyclization imidization reaction of corresponding maleamic acid monoesters (for example, Patent Documents 7 to 9), etc. Among these methods, in the method of obtaining from maleic anhydride and primary amines in one step, there is a problem that the productivity is poor because the yield is still low, and in the method of obtaining from maleamic acid monoesters, there is a problem that the alcohol generated by the cyclization imidization reaction remains and mixes into the product. Therefore, industrially, the method of obtaining by the dehydration cyclization imidization reaction of maleamic acids is generally used. The primary amines in the production of N-phenylmaleimide are aniline, and the maleamic acids are N-phenylmaleamic acids.

[0004] Incidentally, in producing N-phenylmaleimide by the above method, the production of N-phenylmaleamic acid (hereinafter also referred to as PMA) will be involved as an intermediate. When this PMA undergoes hydrolysis, aniline and maleic acid are produced. It is known that the produced aniline (or aniline derived from the raw material) reacts with the target product PMI to produce 2-anilino-N-phenylsuccinimide (hereinafter also referred to as APSI). Further, when PMI containing these intermediates and by-products as impurities is used as one of the copolymerization components for obtaining the resin product as described above, for some reason, the impurities are converted into PMI and its analogs during polymerization or molding, resulting in problems such as the obtained copolymer being colored or discolored, or the quality (heat resistance, strength) of the copolymer being deteriorated.

[0005] In order to solve such problems, for example, Patent Document 10 discloses that after removing the catalyst layer from the reaction mixture after ring-closing imidization, the PMI-containing organic solvent layer is washed with water at a temperature of 55°C or higher, then the organic solvent layer and the aqueous layer are separated, and after distilling off the organic solvent from the organic solvent layer, distillation is carried out at 160°C under a reduced pressure of 3 mmHg to reduce the total content of impurities PMA, APSI, N-(2,5-dioxo-1-phenyl-3-pyrrolidinyl)-N-phenylmaleamic acid (PPMA) and N-phenylfumaramic acid (PFA) to 0.5% by mass or less, thereby producing N-phenylmaleimide.

[0006] However, as disclosed in Example 2 of Patent Document 10, only the production process by water washing and distillation results in a total of 5000 ppm of impurities PMA, APSI, PPMA and PFA contained in N-phenylmaleimide. Therefore, from the viewpoint of solving the problems in the above resin product, the contents of impurities PMA and APSI in PMI are not sufficiently reduced.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

[0008] An object of the present invention is to provide an N-phenylmaleimide compound that improves the color tone of a copolymer, and a copolymer obtained by copolymerization using the N-phenylmaleimide compound as at least one component of a monomer. [Means for Solving the Problems]

[0009] As a result of intensive studies to solve the above-described problems of the prior art, the present inventors have found that specific impurities, specifically N-phenylmaleamic acid (PMA) and 2-anilino-N-phenylsuccinimide (APSI), are denatured into coloring components by heating, and by setting the content of N-phenylmaleamic acid (PMA) to 0.06% by mass or less and the content of 2-anilino-N-phenylsuccinimide (APSI) to 0.01% by mass or less, it has been clarified that the above problems can be solved.

[0010] That is, the present invention is as follows. [1] An N-phenylmaleimide (PMI) compound containing 0.06% by mass or less of N-phenylmaleamic acid (PMA) and 0.01% by mass or less of 2-anilino-N-phenylsuccinimide (APSI). [2] A copolymer using the N-phenylmaleimide compound described in [1] as a raw material. [3] A methacrylic copolymer using the N-phenylmaleimide compound described in [1] as a raw material. [4] A molded article characterized by containing the copolymer according to any one of [2] or [3].

Effects of the Invention

[0011] According to the present invention, a molded article containing a copolymer using an N-phenylmaleimide compound as a raw material, in which the color tone is improved without deteriorating the quality, can be obtained.

Brief Description of the Drawings

[0012]

Figure 1

Modes for Carrying Out the Invention

[0013] Hereinafter, the modes for carrying out the present invention (hereinafter referred to as "the present embodiment") will be described in detail. However, the present invention is not limited to the following description and can be variously modified and implemented within the scope of the gist.

[0014] (N-phenylmaleimide compound) As a method for producing N-substituted maleimide compounds typified by N-phenylmaleimide (PMI), it can be produced by a method as described in the above-mentioned prior art documents and the like, and is not particularly limited. Specifically, (a) a method obtained by subjecting maleic anhydride and primary amines to a dehydration reaction in one step; (b) a method obtained by generating maleamic acids from maleic anhydride and primary amines and subjecting the maleamic acids to a dehydration cyclization imidization reaction; (c) a method obtained by subjecting corresponding maleamic acid monoesters to a cyclization imidization reaction, etc. Among these, the method (b) is preferred. That is, for example, as a method for producing N-phenylmaleimide, a method of reacting maleic anhydride and aniline as raw materials to generate N-phenylmaleamic acid (PMA) and subjecting this N-phenylmaleamic acid to a dehydration cyclization imidization reaction is particularly preferred.

[0015] When producing N-phenylmaleimide by the above method (b), aniline and maleic acid are generated by hydrolysis of N-phenylmaleamic acid (PMA) as an intermediate. The generated aniline, or aniline derived from the raw material, reacts with the target product N-phenylmaleimide to generate 2-anilino-N-phenylsuccinimide (APSI) (see the following reaction formula).

[0016]

Chemical formula

[0017] Here, N-phenylmaleimide (PMI) as referred to in the present invention is a compound having a chemical structure represented by the following formula.

[0018]

Chemical formula

[0019] Also, N-phenylmaleamic acid (PMA) as referred to in the present invention is a compound having a chemical structure represented by the following formula.

[0020] [Chemical formula]

[0021] In addition, 2-anilino-N-phenylsuccinimide (APSI) as referred to in the present invention is a compound having a chemical structure represented by the following formula.

[0022] [Chemical formula]

[0023] As described above, the intermediate PMA can obtain the target product PMI through a dehydration ring-closing imidization reaction, or undergo a hydrolysis reaction to generate aniline and maleic acid, and aniline reacts with PMI to by-produce APSI. However, not all of its total amount will necessarily undergo a complete change through any of these reactions, and it will exist as an impurity in PMI.

[0024] Thus, the N-phenylmaleimide compound (PMI) according to the present invention contains PMA and APSI as impurities. When PMI containing these impurities is used as one component of the copolymer monomer, PMA and APSI will be later converted into PMI and its analogs through dehydration condensation reactions, oxidation reactions, etc. Therefore, as described above, the quality of its molded body, such as appearance, heat resistance, and strength, may deteriorate, and it is desirable to reduce their contents as much as possible.

[0025] As a result of the inventors' research, by heating PMA and APSI alone at 200 °C for 10 minutes each, it can be confirmed from the ultraviolet-visible absorption spectrum that the average gram absorption coefficient at 400 to 500 nm increases from 1.6 L / (g·cm) to 35.5 L / (g·cm) for PMA and from 0.02 L / (g·cm) to 3.3 L / (g·cm) for APSI. It has become clear that PMA and APSI decompose or denature into components having coloring in the visible light region by heating. That is, it has been found that the contents of the above impurities PMA and APSI affect the quality of the copolymer obtained using the N-phenylmaleimide compound, particularly coloring. From the above results, the N-phenylmaleimide compound of the present invention is characterized in that PMA is 0.06% by mass or less and APSI is 0.01% by mass or less with respect to the total amount of the N-phenylmaleimide compound.

[0026] Therefore, in the present invention, N-phenylmaleimide (PMI) containing 0.06% by mass or less of PMA and 0.01% by mass or less of APSI is used as at least one component of the copolymer monomer.

[0027] The content of PMA in the N-phenylmaleimide compound is 0.06% by mass or less with respect to the total amount of the N-phenylmaleimide compound. Here, when an N-phenylmaleimide compound having a PMA content exceeding 0.06% by mass is used as one component of the copolymer monomer, the yellowness index YI of the molded body containing the produced copolymer increases, which is not preferable. Although the detailed mechanism is not clear, it is presumed that the yellowness index YI increases because PMA is heated during polymerization and molding and is converted to PMI by a dehydration condensation reaction, or some PMA is hydrolyzed to generate aniline, which reacts with PMI to generate APSI, and then is oxidized during polymerization or molding to be converted to a PMI analog. The content of PMA in the N-phenylmaleimide compound is 0.06% by mass or less, preferably 0.05% by mass or less, and more preferably 0.02% by mass or less, based on the total amount of the N-phenylmaleimide compound. The lower limit of the content of PMA in the N-phenylmaleimide compound is preferably as low as possible (i.e., 0% by mass), but from an industrial perspective, it is usually more than 0% by mass, and preferably 0.01% by mass or more.

[0028] In addition, the content of APSI in the N-phenylmaleimide compound is 0.01% by mass or less based on the total amount of the N-phenylmaleimide compound. Here, if an N-phenylmaleimide compound having an APSI content exceeding 0.01% by mass is used as one component of the copolymerizable monomer, the yellowness index YI of the molded article containing the produced copolymer increases, which is not preferable. Although the detailed mechanism is not clear, it is presumed that not only APSI itself is colored, but also APSI is oxidized during polymerization or molding and converted into a PMI analog, resulting in coloring. The content of APSI in the N-phenylmaleimide compound is preferably 0.008% by mass or less, and more preferably 0.004% by mass or less, based on the total amount of the N-phenylmaleimide compound. The lower limit of the content of APSI in the N-phenylmaleimide compound is preferably as low as possible (i.e., 0% by mass), but from an industrial perspective, it is usually more than 0% by mass, and preferably 0.002% by mass or more. In this specification, the content of APSI is a value that can be measured by the method described in the following examples.

[0029] (Method for producing N-phenylmaleimide compound) As a method for producing N-substituted maleimide compounds represented by N-phenylmaleimide, as described above, it is not particularly limited, and known methods such as those described in the above-mentioned prior art documents can be applied in the same manner or with appropriate modifications, and can also be applied to N-phenylmaleimide obtained by commercial purchase.

[0030] (Purification method of N-phenylmaleimide compound) The purification method of N-phenylmaleimide according to the present invention can also be obtained by conventionally known purification methods such as the methods described in the above-mentioned patent documents. However, it is preferable because it can be stably and efficiently obtained in the long term by repeating the purification process or making the purification conditions more stringent.

[0031] Hereinafter, preferred embodiments of the purification method according to the present invention will be described. However, the present invention is not limited to the following forms. That is, for example, a method in which solid PMI is dissolved in an organic solvent, washed with water at 30°C or lower to remove impurities, and then dried; a method in which solid PMI is dissolved in an organic solvent, washed with an acidic or basic aqueous solution, and the solution is dried; a method in which solid PMI is completely dissolved in an organic solvent, filtered through a filter to remove impurities, and then the filtrate is dried, etc. can be used. Among them, a method in which solid PMI is completely dissolved in an organic solvent, filtered through a filter to remove impurities, and then the filtrate is dried is more preferable in terms of suppressing the hydrolysis of PMI.

[0032] (Purification method by filtration) The purification method of N-phenylmaleimide according to the present invention is preferably a purification method using a filter filtration step that utilizes the difference in solubility of impurities and N-phenylmaleimide in a solvent.

[0033] The organic solvents that can be used when purifying PMI herein are not particularly limited, but solvents that are insoluble or immiscible with water and are inert (do not participate in the reaction) are preferred. Such solvents include, for example, benzene, toluene, petroleum fractions with a boiling point of 50 to 120 °C, xylene, ethylbenzene, isopropylbenzene, cumene, mesitylene, tert-butylbenzene, methoxybenzene, pseudocumene, trimethylhexane, octane, tetrachloroethane, nonane, chlorobenzene, ethylcyclohexane, petroleum fractions with a boiling point of 120 to 170 °C, m-dichlorobenzene, sec-butylbenzene, p-dichlorobenzene, decane, p-cymene, o-dichlorobenzene, butylbenzene, decahydronaphthalene, tetrahydronaphthalene, dodecane, naphthalene, cyclohexylbenzene, petroleum fractions with a boiling point of 170 to 250 °C, and the like. The above organic solvents may be used alone or in the form of a mixture of two or more.

[0034] The amount of the above organic solvent used is not particularly limited, but those that can perform filtration smoothly and have a large difference between the solubility of PMI and the solubilities of PMA and APSI are selected. Furthermore, considering the separation of PMI and the solvent after purification, it may be advantageous to use a low-boiling solvent and perform purification under pressure. Here, the concentration of PMI during filter filtration is not particularly limited as long as PMI can be dissolved. Specifically, it is preferably added and dissolved at 1 to 50 g, more preferably 5 to 30 g, and even more preferably 10 to 20 g of the organic solvent per 1 g of PMI.

[0035] Also, the weight ratio of PMA to PMI contained in the mixture of PMI and the organic solvent for performing filter filtration is preferably PMA / PMI = 6×10 -5 or less. Here, when the weight ratio of PMA to PMI is PMA / PMI = 6×10 -5 or more, too much PMA dissolves in the organic solvent and cannot be removed by filtration, so the PMA content in PMI cannot be sufficiently reduced. It is more preferably that the weight ratio of PMA to PMI is PMA / PMI = 4×10 -5 or less, and PMA / PMI = 3×10 -5The following are particularly preferred. The above weight ratio can be controlled by the temperature of the mixture and the type of solvent.

[0036] The temperature at which the filter filtration is carried out is not particularly limited, but from the viewpoint of increasing the solubility difference between PMA and APSI and the solubility of PMI, it is preferably 60 °C or lower, more preferably 40 °C or lower, and particularly preferably 20 °C or lower.

[0037] The pore size of the filter used for filtration is not particularly limited, but from the viewpoint of the efficiency of the filter capturing PMA and APSI, it is preferably 1 μm or less, more preferably 0.5 μm or less, and particularly preferably 0.2 μm or less.

[0038] By the above method, an N-phenylmaleimide compound containing 0.06% by mass or less of N-phenylmaleamic acid (PMA) and 0.01% by mass or less of 2-anilino-N-phenylsuccinimide (APSI) can be obtained. As described above, since the N-phenylmaleimide compound of the present invention has a very low content of these impurities, the copolymer obtained using this N-phenylmaleide compound has a low content of colored compounds derived from impurities that may be generated during polymerization, and the coloring of the molded body can be reduced.

[0039] (Copolymer using an N-phenylmaleimide compound as a raw material) The copolymer of the present invention is obtained by copolymerizing an N-phenylmaleimide compound (PMI) and one or more other monomers copolymerizable with the N-phenylmaleimide compound. Here, the monomers other than PMI used as production raw materials (other monomers) are not particularly limited as long as they are copolymerizable with PMI. Specifically, examples of other monomers include maleimide compounds (excluding N-phenylmaleimide), methacrylic acid esters, aromatic vinyls, acrylic acid esters, unsaturated nitriles, olefins, dienes, vinyl ethers, vinyl esters, vinyl fluorides, allyl esters of saturated fatty acid monocarboxylic acids such as allyl propionate or (meth)acrylic esters, polyvalent (meth)acrylates, polyvalent allylates, glycidyl compounds, unsaturated carboxylic acids, etc. Among these exemplified compounds, maleimide compounds, methacrylic acid esters, aromatic vinyls, and acrylic acid esters are particularly preferred. Note that the above other monomers may be used alone or in the form of a mixture of two or more kinds.

[0040] The structural unit derived from the maleimide compound in the copolymer using the maleimide compound is formed from at least one selected from the monomers represented by the following formula (1).

[0041]

Chemical formula

[0042] Examples of the monomer represented by the formula (1) include N-benzylmaleimide, N-(2-chlorophenyl)maleimide, N-(4-chlorophenyl)maleimide, N-(4-bromophenyl)maleimide, N-(2-methylphenyl)maleimide, N-(2-ethylphenyl)maleimide, N-(2-methoxyphenyl)maleimide, N-(2-nitrophenyl)maleimide, N-(2,4,6-trimethylphenyl)maleimide, N-(4-benzylphenyl)maleimide, N-(2,4,6-tribromophenyl)maleimide, N-naphthylmaleimide, N-anthracenylmaleimide, 3-methyl-1-phenyl-1H-pyrrole-2,5-dione, 3,4-dimethyl-1-phenyl-1H-pyrrole-2,5-dione, 1,3-diphenyl-1H-pyrrole-2,5-dione, 1,3,4-triphenyl-1H-pyrrole-2,5-dione, 2-anilino-N-phenylmaleimide, and the like. Among these monomers, N-cyclohexylmaleimide and N-benzylmaleimide are preferably used in consideration of the ease of availability and the physical properties of the resulting copolymer. In addition, a plurality of these maleimide compounds can be used in combination. The molar ratio (A1 / A2) of the content (A1) of the structural unit derived from PMI to the content (A2) of the structural unit derived from the monomer represented by the formula (1) is preferably more than 0 and 15 or less, more preferably more than 0 and 10 or less. When the molar ratio A1 / A2 is within this range, the molded article containing the copolymer of this embodiment maintains transparency, does not involve yellowing, and exhibits good heat resistance without impairing the environmental resistance.

[0043] The monomer forming the methacrylic acid ester monomer unit constituting the copolymer of this embodiment is formed from at least one selected from the monomers represented by the following formula (2).

[0044]

Chemical formula

[0045] Examples of the monomer represented by formula (2) include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, amyl methacrylate, 2-ethylhexyl methacrylate, cyclopentyl methacrylate, cyclohexyl methacrylate, cyclooctyl methacrylate, tricyclodecyl methacrylate, dicyclooctyl methacrylate, tricyclododecyl methacrylate, isobornyl methacrylate, phenyl methacrylate, benzyl methacrylate, 1-phenylethyl methacrylate, 2-phenoxyethyl methacrylate, 3-phenylpropyl methacrylate, 2,4,6-tribromophenyl methacrylate, and the like. These monomers may be used alone or in combination of two or more. Among the above methacrylic acid esters, methyl methacrylate and benzyl methacrylate are preferable in terms of excellent transparency and weather resistance of the resulting methacrylic resin. The structural unit derived from the methacrylic acid ester monomer may contain only one kind or two or more kinds.

[0046] The monomer forming the aromatic vinyl-based monomer unit constituting the copolymer of the present embodiment is not particularly limited, but an aromatic vinyl-based monomer represented by the following general formula (3) is preferable.

[0047]

Chemical formula

[0048] Specific examples of the monomer represented by the general formula (3) are not particularly limited, but include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, 2,4-dimethylstyrene, 2,5-dimethylstyrene, 3,4-dimethylstyrene, 3,5-dimethylstyrene, p-ethylstyrene, m-ethylstyrene, o-ethylstyrene, p-tert-butylstyrene, 1-vinylnaphthalene, 2-vinylnaphthalene, 1,1-diphenylethylene, isopropenylbenzene (α-methylstyrene), isopropenyltoluene, isopropenylethylbenzene, isopropenylpropylbenzene, isopropenylbutylbenzene, isopropenylpentylbenzene, isopropenylhexylbenzene, isopropenyloctylbenzene, α-hydroxymethylstyrene, α-hydroxyethylstyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, etc. Among these, styrene and isopropenylbenzene are preferable, and styrene is more preferable from the viewpoints of imparting fluidity and reducing unreacted monomers by improving the polymerization conversion rate. These may be appropriately selected according to the required characteristics in the copolymer of the present embodiment.

[0049] When using the aromatic vinyl monomer unit (B1), the ratio (mass ratio) of the content of the (B1) monomer unit to the total content (A3) of the PMI structural unit and the maleimide structural unit described above (that is, (B1) content / (A3) content) is preferably 0.3 to 5 from the viewpoints of the processing fluidity when forming the film and the effect of reducing silver streaks by reducing residual monomers. Here, from the viewpoint of maintaining good color tone and heat resistance, the upper limit value is preferably 5 or less, more preferably 3 or less, and still more preferably 1 or less. Also, from the viewpoint of reducing residual monomers, the lower limit value is preferably 0.3 or more, more preferably 0.4 or more. The above-mentioned aromatic vinyl monomer may be used alone or in combination of two or more.

[0050] The monomer forming the acrylate monomer unit constituting the copolymer of the present embodiment is not particularly limited, but an acrylate monomer represented by the following general formula (4) is preferable.

[0051]

Chemical formula

[0052] As the monomer for forming the acrylic acid ester monomer unit, in the methacrylic resin for the film of the present embodiment, from the viewpoints of enhancing weather resistance, heat resistance, fluidity, and thermal stability, methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, sec-butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, phenyl acrylate, etc. are preferable, and more preferably, methyl acrylate, ethyl acrylate, and n-butyl acrylate. From the viewpoint of easy availability, methyl acrylate and ethyl acrylate are even more preferable. Only one kind of the above acrylic acid ester monomer unit may be used alone, or two or more kinds may be used in combination.

[0053] The monomer forming the vinyl cyanide-based monomer unit constituting the copolymer of the present embodiment is not particularly limited. For example, acrylonitrile, methacrylonitrile, ethacrylonitrile, vinylidene cyanide, etc. may be mentioned. Among them, acrylonitrile is preferable from the viewpoints of easy availability and imparting chemical resistance. Only one kind of the above vinyl cyanide-based monomer unit may be used alone, or two or more kinds may be used in combination.

[0054] The monomers forming the monomer units other than maleimides, methacrylic acid esters, aromatic vinyls, acrylic acid esters, and vinyl cyanides in the copolymer of the present embodiment are not particularly limited. For example, amides such as acrylamide and methacrylamide; glycidyl compounds such as glycidyl (meth)acrylate and allyl glycidyl ether; unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, and fumaric acid, and their semi-esterified products or anhydrides; unsaturated alcohols such as methallyl alcohol and allyl alcohol; olefins such as ethylene, propylene, and 4-methyl-1-pentene; dienes such as butadiene and isoprene; vinyl fluorides such as vinylidene fluoride; and vinyl compounds or vinylidene compounds other than the above such as vinyl acetate, 2-hydroxymethyl-1-butene, methyl vinyl ketone, N-vinylpyrrolidone, and N-vinylcarbazole. Furthermore, as the crosslinkable compound having a plurality of reactive double bonds, those obtained by esterifying both terminal hydroxyl groups of ethylene glycol or its oligomer such as ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, and tetraethylene glycol di(meth)acrylate with acrylic acid or methacrylic acid; those obtained by esterifying the hydroxyl groups of two alcohols such as neopentyl glycol di(meth)acrylate and di(meth)acrylate with acrylic acid or methacrylic acid; those obtained by esterifying polyhydric alcohol derivatives such as trimethylolpropane and pentaerythritol with acrylic acid or methacrylic acid; polyfunctional monomers such as divinylbenzene, etc. can be mentioned.

[0055] Among the monomers constituting the above-mentioned monomer units, at least one selected from the group consisting of N-cyclohexylmaleimide, N-benzylmaleimide, methyl methacrylate, benzyl methacrylate, methyl acrylate, ethyl acrylate, styrene, and acrylonitrile is preferable from the viewpoint of easy availability.

[0056] The content of monomers other than the above-mentioned PMI is not particularly limited as long as the resulting copolymer satisfies the glass transition temperature range of the present embodiment. However, based on 100% by mass of the copolymer, it is preferably in the range of 50 to 95% by mass, more preferably in the range of 60 to 95% by mass, and even more preferably in the range of 65 to 95% by mass. When within this range, the molded article containing the copolymer can obtain a more sufficient heat resistance improvement effect, and more preferable improvement effects can be obtained for weather resistance, low water absorption, and optical properties. When the content of monomers other than the above-mentioned PMI is less than 50% by mass, the viscosity of the resulting copolymer during melting tends to increase, which is disadvantageous in terms of molding processability. When it exceeds 95% by weight, it tends to be difficult to recognize the improvement in heat resistance due to the structure derived from PMI. That is, when producing the copolymer according to the present invention, the content of the N-phenylmaleimide compound is preferably in the range of 5 to 50% by mass, more preferably in the range of 5 to 40% by mass, and even more preferably in the range of 5 to 35% based on 100% by mass of the copolymer. With such an amount, the heat resistance by N-phenylmaleimide can be sufficiently improved.

[0057] Hereinafter, the characteristics of the copolymer of the present embodiment will be described.

[0058] (Glass transition temperature) The glass transition temperature (Tg) of the copolymer of the present embodiment is preferably above 120°C and below 160°C. If the glass transition temperature of the copolymer exceeds 120°C, it is easier to obtain the necessary and sufficient heat resistance for optical components such as lens molded articles in recent years, automotive components such as in-vehicle displays, film molded articles for liquid crystal displays, optical films, etc. From the perspective of dimensional stability at the use environment temperature, the glass transition temperature (Tg) is more preferably 125°C or higher, and even more preferably 130°C or higher. On the other hand, when the glass transition temperature (Tg) of the copolymer is 160°C or lower, extreme high-temperature melt processing can be avoided, thermal decomposition of resins, etc. can be suppressed, and good products can be obtained. For the above reasons, the glass transition temperature (Tg) is preferably 150°C or lower. The glass transition temperature (Tg) can be determined by measuring in accordance with JIS-K7121. Specifically, it can be measured using the method described in the examples below.

[0059] (Weight-average molecular weight) The copolymer of this embodiment preferably has a weight-average molecular weight (Mw) in terms of polymethyl methacrylate measured by gel permeation chromatography (GPC) in the range of 65,000 to 220,000, more preferably in the range of 80,000 to 180,000, and even more preferably in the range of 90,000 to 150,000. When the weight-average molecular weight (Mw) is within the above range, the balance between mechanical strength and fluidity is also excellent. Regarding the ratios among the Z-average molecular weight (Mz), weight-average molecular weight (Mw), and number-average molecular weight (Mn) as parameters representing the molecular weight distribution, in the copolymer of this embodiment, considering the balance between fluidity and mechanical strength, Mw / Mn is preferably 1.5 to 3.0, more preferably 1.6 to 2.5, and even more preferably 1.6 to 2.3; Mz / Mw is preferably 1.3 to 2.0, more preferably 1.3 to 1.8, and even more preferably 1.4 to 1.7. Note that the weight-average molecular weight and number-average molecular weight of the copolymer can be measured by the methods described in the examples below.

[0060] (Method for producing the copolymer) Hereinafter, the method for producing the copolymer of this embodiment will be described. In the manufacturing method of the present embodiment, as the polymerization method, a batch process, a semi-batch process, or a continuous process can be used. Here, the batch process is a process in which the reaction is started and allowed to proceed after all the raw materials are charged into the reactor, and the product is recovered after completion. The semi-batch process is a process in which either the raw material charging or the product recovery is carried out simultaneously during the reaction progress. The continuous process is a process in which both the raw material charging and the product recovery are carried out simultaneously during the reaction progress. As the manufacturing method of the copolymer having a ring structure in the main chain in the present embodiment, from the viewpoint of precisely controlling the copolymer composition, a semi-batch process in which a part of the raw materials are charged after the start of the reaction is preferable. In the manufacturing method of the copolymer in the present embodiment, it is preferable to use the polymerization of monomers by radical polymerization.

[0061] Hereinafter, the manufacturing method of the methacrylic copolymer obtained by copolymerization with a methacrylic acid ester will be described in detail. As the manufacturing method of the methacrylic copolymer in the present embodiment, the solution polymerization method is preferable.

[0062] The polymerization solvent to be used is not particularly limited as long as it can increase the solubility of the methacrylic copolymer obtained by polymerization and can appropriately maintain the viscosity of the reaction solution for the purpose of preventing gelation. Specific examples of the polymerization solvent include aromatic hydrocarbons such as toluene, xylene, ethylbenzene, and isopropylbenzene; ketones such as methyl isobutyl ketone, butyl cellosolve, methyl ethyl ketone, and cyclohexanone; and polar solvents such as dimethylformamide and 2-methylpyrrolidone. Also, alcohols such as methanol, ethanol, and isopropanol may be used in combination as the polymerization solvent within a range that does not inhibit the dissolution of the polymerization product during polymerization. These may be used alone or in combination of two or more.

[0063] The amount of the solvent at the time of polymerization is not particularly limited as long as the polymerization proceeds, no precipitation of the copolymer or the monomer used occurs during production, and it can be easily removed. For example, when the total amount of the monomers to be blended is 100 parts by mass, it is preferably 10 to 200 parts by mass. More preferably, it is 25 to 200 parts by mass, still more preferably 50 to 200 parts by mass, and even more preferably 50 to 150 parts by mass.

[0064] The polymerization temperature is not particularly limited as long as the polymerization proceeds, but it is preferably 70 to 180°C, more preferably 80 to 160°C, still more preferably 90 to 150°C, and even more preferably 100 to 150°C. From the viewpoint of productivity, it is preferably 70°C or higher, and from the viewpoint of suppressing side reactions during polymerization and obtaining a polymer with a desired molecular weight and quality, it is preferably 180°C or lower.

[0065] Regarding the polymerization time, there is no particular limitation as long as the required degree of polymerization can be obtained at the required conversion rate. However, from the viewpoints of productivity and the like, it is preferably 2 to 15 hours, more preferably 3 to 12 hours, and still more preferably 4 to 10 hours.

[0066] The polymerization conversion rate at the end of the polymerization of the methacrylic copolymer in this embodiment is preferably 93 to 99.9%, more preferably 95 to 99.9%, and still more preferably 97 to 99.8%. Here, the polymerization conversion rate is the ratio of the value obtained by subtracting the total mass of the monomers remaining at the end of the polymerization from the total mass of the monomers added to the polymerization system to the total mass of the monomers added to the polymerization system.

[0067] The amount of the PMI monomer remaining (PMI residual amount) in the solution after polymerization is preferably 0.005 to 0.5% by mass, more preferably 0.01 to 0.3% by mass, and still more preferably 0.02 to 0.1% by mass. The higher the coincidence conversion rate and the lower the PMI residual amount, the less monomer returns to the solvent recovery system, so the load on the purification system is reduced, and the yield increases, making it economical. However, if the polymerization conversion rate is too high or the PMI residual amount is reduced too much, the amount of low molecular weight components with poor colorability increases, which may have an adverse effect on the color tone and molding processability.

[0068] During the polymerization reaction, a chain transfer agent may be added and polymerized as necessary. As the chain transfer agent, any chain transfer agent used in general radical polymerization can be used. For example, mercaptan compounds such as n-butyl mercaptan, n-octyl mercaptan, n-decyl mercaptan, n-dodecyl mercaptan, 2-ethylhexyl thioglycolate; halogen compounds such as carbon tetrachloride, methylene chloride, bromoform; unsaturated hydrocarbon compounds such as α-methylstyrene dimer, α-terpinene, dipentene, terpinolene; etc. can be mentioned. These may be used alone or in combination of two or more. These chain transfer agents may be added at any stage as long as the polymerization reaction is in progress, and are not particularly limited. The addition amount of the chain transfer agent may be 0.01 to 1% by mass, preferably 0.05 to 0.5% by mass, when the total amount of the monomers used in the polymerization is 100% by mass.

[0069] Also, a polymerization initiator may be added during the polymerization reaction. As the polymerization initiator, any initiator generally used in radical polymerization can be used. For example, organic peroxides such as cumene hydroperoxide, diisopropylbenzene hydroperoxide, di-t-butyl peroxide, lauroyl peroxide, benzoyl peroxide, t-butyl peroxyisopropyl carbonate, t-amyl peroxy-2-ethylhexanoate, t-amyl peroxyisononanoate, 1,1-di-t-butyl peroxycyclohexane; azo compounds such as 2,2’-azobis(isobutyronitrile), 1,1’-azobis(cyclohexanecarbonitrile), 2,2’-azobis(2,4-dimethylvaleronitrile), dimethyl-2,2’-azobisisobutyrate; etc. can be mentioned. These may be used alone or in combination of two or more. These polymerization initiators may be added at any stage as long as the polymerization reaction is in progress. As the addition amount of the polymerization initiator, when the total amount of the monomers used in the polymerization is 100% by mass, it may be 0.01 to 1% by mass, preferably 0.05 to 0.5% by mass.

[0070] In solution polymerization, it is important to reduce the dissolved oxygen concentration in the polymerization solution as much as possible. For example, the dissolved oxygen concentration is preferably 10 ppm or less. The dissolved oxygen concentration can be measured, for example, using a dissolved oxygen meter DO meter B-505 (manufactured by Iijima Electronics Industry Co., Ltd.). As a method for reducing the dissolved oxygen concentration, methods such as bubbling an inert gas into the polymerization solution, repeating the operation of pressurizing the container containing the polymerization solution with an inert gas to about 0.2 MPa and then releasing the pressure before polymerization, and passing an inert gas through the container containing the polymerization solution can be appropriately selected.

[0071] In order to reduce the difference in the bonded monomer composition among copolymers with different molecular weights, it is preferable to carry out polymerization while additionally adding some monomer units so that the monomer composition in the polymerization system during polymerization becomes as uniform as possible. For example, the difference in the consumption rate of each monomer when about 70% of the total amount of monomers finally added to the system has been consumed is preferably 10% or less, more preferably 5% or less, and even more preferably 3% or less. Adjust the type, amount, and timing of the additionally added monomers. Furthermore, the polymerization is carried out so that the difference in the final conversion rate among the monomers at the end of polymerization is 10% or less, more preferably 5% or less, and even more preferably 3% or less. Note that the consumption rate of a certain monomer at a certain time point refers to the ratio of the amount of the monomer consumed in the polymerization reaction out of the total amount of the monomer added, and the total amount of the monomer added includes both the amount already added and the amount not yet added at a certain time point.

[0072] The method for recovering the polymer from the polymerization solution obtained by solution polymerization is not particularly limited. For example, after adding the polymerization solution into an excessive amount of a poor solvent such as a hydrocarbon-based solvent or an alcohol-based solvent in which the polymerization product obtained by polymerization does not dissolve, treatment (emulsification and dispersion) is performed with a homogenizer, and pretreatment such as liquid-liquid extraction and solid-liquid extraction is performed on the unreacted monomer to separate it from the polymerization solution; or a method of separating the polymerization solvent and the unreacted monomer through a process called a devolatilization step and recovering the polymerization product; etc. can be mentioned. Here, the devolatilization step refers to a step of removing volatile components such as the polymerization solvent, residual monomers, and reaction by-products under heating and reduced pressure conditions.

[0073] Examples of the apparatus used in the devolatilization step include a devolatilization apparatus composed of a tubular heat exchanger and a devolatilization tank; thin-film evaporators such as Wiplen and Exeva manufactured by Shinko Environmental Solutions Co., Ltd., Contra and Inclined Blade Contra manufactured by Hitachi, Ltd.; an extruder with a vent having a residence time and surface area sufficient to exhibit devolatilization performance; etc. It is also possible to utilize a devolatilization step using a devolatilization apparatus combining any two or more of these apparatuses.

[0074] The treatment temperature in the devolatilization device is preferably 150 to 350 °C, more preferably 170 to 300 °C, and even more preferably 200 to 280 °C. By setting the temperature above the lower limit, the residual volatile content can be suppressed, and by setting the temperature below the upper limit, coloring and decomposition of the resulting acrylic resin can be suppressed.

[0075] As the degree of vacuum in the devolatilization device, it is preferably used in the range of 10 to 500 Torr, and more preferably in the range of 10 to 300 Torr. By setting the degree of vacuum below the upper limit value, the remaining amount of volatile components can be suppressed. Also, a degree of vacuum above the lower limit value is realistic for industrial implementation. The treatment time is appropriately selected according to the amount of residual volatile content, but it is preferably as short as possible in order to suppress coloring and decomposition of the resulting acrylic resin.

[0076] The polymer recovered through the devolatilization step may be processed into pellets in a step called the pelletizing step. In the pelletizing step, the molten resin may be extruded in a strand shape through a porous die and processed into pellets by a cold cut method, an air hot cut method, or an under water cut method.

[0077] When a vented extruder is adopted as the devolatilization device, the devolatilization step and the pelletizing step may be combined.

[0078] (Composition containing methacrylic copolymer) The composition containing the methacrylic copolymer of the present embodiment contains the methacrylic copolymer of the present embodiment described above. The composition containing the methacrylic copolymer may optionally contain additives in addition to the methacrylic copolymer of the present embodiment described above, and may also contain other thermoplastic polymers, rubbery polymers, etc. other than the methacrylic copolymer, or may contain only the methacrylic copolymer. The content of the methacrylic copolymer in 100% by mass of the composition containing the methacrylic copolymer is preferably 50% by mass or more, more preferably 60% by mass or more, still more preferably 70% by mass or more, and particularly preferably 80% by mass or more.

[0079] - Additives - The composition containing the methacrylic copolymer according to this embodiment may contain various additives as long as the effects of the present invention are not significantly impaired. The additives are not particularly limited, and examples thereof include antioxidants, light stabilizers such as hindered amine light stabilizers, ultraviolet absorbers, mold release agents, other thermoplastic polymers, paraffinic process oils, naphthenic process oils, aromatic process oils, paraffin, organopolysiloxanes, softeners / plasticizers such as mineral oils, flame retardants, antistatic agents, inorganic fillers such as pigments such as organic fibers and iron oxides, reinforcing agents such as glass fibers, carbon fibers, and metal whiskers, colorants; organic phosphorus compounds such as phosphites, phosphonites, and phosphates, other additives, or mixtures thereof.

[0080] -- Antioxidant -- The methacrylic resin composition according to this embodiment preferably contains an antioxidant that suppresses deterioration and coloring during molding or use. Examples of the antioxidant include, but are not limited to, hindered phenol antioxidants, phosphorus antioxidants, sulfur antioxidants, etc. The methacrylic copolymer of this embodiment is suitably used in various applications such as melt extrusion, injection molding, and film molding applications. The thermal history received during processing varies depending on the processing method, and ranges from about several tens of seconds like an extruder to those receiving a thermal history of several tens of minutes to several hours like the molding of thick-walled products or sheet molding. When undergoing a long-term heat history, it is necessary to increase the addition amount of the heat stabilizer to obtain the desired heat stability. From the viewpoints of suppressing the bleed-out of the heat stabilizer and preventing the film from sticking to the roll during film formation, it is preferable to use a plurality of types of heat stabilizers in combination. For example, it is preferable to use in combination at least one selected from phosphorus-based antioxidants and sulfur-based antioxidants and a hindered phenol-based antioxidant. These antioxidants may be used alone or in combination of two or more.

[0081] Examples of the hindered phenol antioxidant include, but are not limited to, pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], thiodiethylene bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 3,3’,3’’,5,5’,5’’-hexa-tert-butyl-a,a’,a’’-(mesitylene-2,4,6-triyl)tri-p-cresol, 4,6-bis(octylthiomethyl)-o-cresol, 4,6-bis(dodecylthiomethyl)-o-cresol, ethylene bis(oxyethylene) bis[3-(5-tert-butyl-4-hydroxy-m-tolyl)propionate], hexamethylene bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 1,3,5-tris[(4-tert-butyl-3-hydroxy-2,6-xylyl)methyl]-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 2,6-di-tert-butyl-4-(4,6-bis(octylthio)-1,3,5-triazin-2-ylamine)phenol, 2-[1-(2-hydroxy-3,5-di-tert-pentylphenyl)ethyl]-4,6-di-tert-pentylphenyl acrylate, 2-tert-butyl-4-methyl-6-(2-hydroxy-3-tert-butyl-5-methylbenzyl)phenyl acrylate, and the like. Particularly preferred are pentaerythritol terakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], octadecyl 3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, and 2-[1-(2-hydroxy-3,5-di-tert-pentylphenyl)ethyl]-4,6-di-tert-pentylphenyl acrylate.

[0082] In addition, as the antioxidant, a hindered phenol-based antioxidant may be a commercially available phenol-based antioxidant. Such commercially available phenol-based antioxidants include, but are not limited to, for example, Irganox 1010 (Irganox 1010: pentaerythritol tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], manufactured by BASF), Irganox 1076 (Irganox 1076: octadecyl 3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, manufactured by BASF), Irganox 1330 (Irganox 1330: 3,3’,3’’,5,5’,5’’-hexa-t-butyl-a,a’,a’’-(mesitylene-2,4,6-triyl)tri-p-cresol, manufactured by BASF), Irganox 3114 (Irganox3114: 1,3,5-tris(3,5-di-t-butyl-4-hydroxybenzyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, manufactured by BASF), Irganox 3125 (Irganox 3125, manufactured by BASF), Adeka Stab AO-60 (pentaerythritol tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], manufactured by ADEKA), Adeka Stab AO-80 (3,9-bis{2-[3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxyoxy]-1,1-dimethylethyl}-2,4,8,10-tetraoxaspiro[5.5]undecane, manufactured by ADEKA), Sumilizer BHT (Sumilizer BHT, manufactured by Sumitomo Chemical), Cyanox 1790 (Cyanox 1790, manufactured by Cytec), Sumilizer GA-80 (Sumilizer GA-80, manufactured by Sumitomo Chemical), Sumilizer GS (Sumilizer GS: 2-[1-(2-hydroxy-3,5-di-tert-pentylphenyl)ethyl]-4,6-di-tert-pentylphenyl acrylate, manufactured by Sumitomo Chemical), Sumilizer GM (Sumilizer GM: 2-tert-butyl-4-methyl-6-(2-hydroxy-3-tert-butyl-5-methylbenzyl)phenyl acrylate, manufactured by Sumitomo Chemical), vitamin E (manufactured by Eisai), and the like. Among these commercially available phenolic antioxidants, from the viewpoint of the effect of imparting thermal stability to the resin, Irganox 1010, Adeka Stab AO-60, Adeka Stab AO-80, Irganox 1076, Sumilizer GS, etc. are preferable. These may be used alone or in combination of two or more.

[0083] In addition, examples of the phosphorus-based antioxidant as the antioxidant include, but are not limited to, tris(2,4-di-t-butylphenyl) phosphite, bis(2,4-bis(1,1-dimethylethyl)-6-methylphenyl) ethyl ester phosphite, tetrakis(2,4-di-t-butylphenyl)(1,1-biphenyl)-4,4'-diylbisphosphonite, bis(2,4-di-t-butylphenyl)pentaerythritol diphosphite, bis(2,6-di-t-butyl-4-methylphenyl)pentaerythritol diphosphite, bis(2,4-dicumylphenyl)pentaerythritol-diphosphite, tetrakis(2,4-t-butylphenyl)(1,1-biphenyl)-4,4'-diylbisphosphonite, di-t-butyl-m-cresyl-phosphonite, 4-[3-[(2,4,8,10-tetra-tert-butyldibenzod[f][1,3,2]dioxaphosphepin)-6-yloxy]propyl]-2-methyl-6-tert-butylphenol, and the like. Furthermore, a commercially available phosphorus-based antioxidant may be used as the phosphorus-based antioxidant. Examples of such commercially available phosphorus-based antioxidants include, but are not limited to, Irgafos 168 (tris(2,4-di-t-butylphenyl) phosphite, manufactured by BASF), Irgafos 12 (tris[2-[[2,4,8,10-tetra-t-butyldibenzo[d,f][1,3,2] dioxaphosphocin-6-yl]oxy]ethyl]amine, manufactured by BASF), Irgafos 38 (bis(2,4-bis(1,1-dimethylethyl)-6-methylphenyl) ethyl ester phosphite, manufactured by BASF), ADK STAB 329K (manufactured by ADEKA), ADK STAB PEP-36 (manufactured by ADEKA), ADK STAB PEP-36A (manufactured by ADEKA), ADK STAB PEP-8 (manufactured by ADEKA), ADK STAB HP-10 (manufactured by ADEKA), ADK STAB 2112 (manufactured by ADEKA), ADK STAB 1178 (manufactured by ADEKA), ADK STAB 1500 (manufactured by ADEKA), Sandstab P-EPQ (manufactured by Clariant), Weston 618 (manufactured by GE), Weston 619G (manufactured by GE), Ultranox 626 (manufactured by GE), Sumilizer GP (4-[3-[(2,4,8,10-tetra-tert-butyldibenzo[d,f][1,3,2] dioxaphosphocin)-6-yloxy]propyl]-2-methyl-6-tert-butylphenol, manufactured by Sumitomo Chemical), HCA (9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, manufactured by Sanko Co., Ltd.), and the like. Among these commercially available phosphorus-based antioxidants, from the viewpoints of the effect of imparting thermal stability to the resin and the combined effect with various antioxidants, Irgafos 168, AdekaStab PEP-36, AdekaStab PEP-36A, AdekaStab HP-10, and AdekaStab 1178 are preferred, and AdekaStab PEP-36A and AdekaStab PEP-36 are particularly preferred. These phosphorus-based antioxidants may be used alone or in combination of two or more.

[0084] In addition, examples of the sulfur-based antioxidants as the antioxidants include, but are not limited to, 2,4-bis(dodecylthiomethyl)-6-methylphenol (Irganoix 1726, manufactured by BASF), 2,4-bis(octylthiomethyl)-6-methylphenol (Irganoix 1520L, manufactured by BASF), 2,2-bis{[3-(dodecylthio)-1-oxopropoxy]methyl}propane-1,3-diylbis[3-dodecylthio]propionate (AdekaStab AO-412S, manufactured by ADEKA), 2,2-bis{[3-(dodecylthio)-1-oxopropoxy]methyl}propane-1,3-diylbis[3-dodecylthio]propionate (Cheminox PLS, manufactured by Chemipro Kasei Co., Ltd.), di(tridecyl) 3,3'-thiodipropionate (AO-503, manufactured by ADEKA), and the like. Among these commercially available sulfur antioxidants, from the viewpoints of the effect of imparting thermal stability to the resin, the combined effect with various antioxidants, and the handleability, AdekaStab AO-412S and Cheminox PLS are preferred. These sulfur-based antioxidants may be used alone or in combination of two or more.

[0085] The content of the antioxidant may be any amount as long as it can achieve the effect of improving thermal stability. If the content is excessive, problems such as bleeding out during processing may occur. Therefore, it is preferably 5 parts by mass or less, more preferably 3 parts by mass or less, still more preferably 1 part by mass or less, even more preferably 0.8 part by mass or less, even more preferably 0.01 to 0.8 part by mass, and particularly preferably 0.01 to 0.5 part by mass, based on 100 parts by mass of the methacrylic copolymer.

[0086] There is no particular limitation on the timing of adding the antioxidant. Examples include a method of starting polymerization after adding it to the monomer solution before polymerization, a method of subjecting it to a devolatilization step after adding and mixing it to the polymer solution after polymerization, a method of pelletizing after adding and mixing it to the molten polymer after devolatilization, and a method of adding and mixing it when remelting and extruding the pellets after devolatilization and pelletizing. Among these, from the perspective of preventing thermal degradation and coloring in the devolatilization step, it is preferable to add the antioxidant after adding and mixing it to the polymer solution after polymerization and then subject it to the devolatilization step before the devolatilization step.

[0087] --Hindered amine light stabilizer-- The composition containing the methacrylic copolymer of the present embodiment may contain a hindered amine light stabilizer. The hindered amine light stabilizer is not particularly limited, but is preferably a compound containing three or more ring structures. Here, the ring structure is preferably at least one selected from the group consisting of an aromatic ring, an aliphatic ring, an aromatic heterocyclic ring, and a non-aromatic heterocyclic ring. When one compound has two or more ring structures, they may be the same or different from each other.

[0088] Examples of hindered amine light stabilizers include, but are not limited to, for example, specifically, bis(1,2,2,6,6-pentamethyl-4-piperidyl) [[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]methyl]butyl malonate, a mixture of bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate and methyl 1,2,2,6,6-pentamethyl-4-piperidyl sebacate, bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate, N,N'-bis(2,2,6,6-tetramethyl-4-piperidyl)-N,N'-diformylhexamethylenediamine, dibutylamine·1,3,5-triazine·N,N'-bis(2,2,6,6-tetramethyl-4-piperidyl-1,6-hexamethylenediamine and a polycondensate of N-(2,2,6,6-tetramethyl-4-piperidyl)butylamine, poly[{6-(1,1,3,3-tetramethylbutyl)amino-1,3,5-triazine-2,4-diyl}{(2,2,6,6-tetramethyl-4-piperidyl)imino}hexamethylene{(2,2,6,6-tetramethyl-4-piperidyl)imino}], tetrakis(1,2,2,6,6-pentamethyl-4-piperidyl) butane-1,2,3,4-tetracarboxylate, tetrakis(2,2,6,6-tetramethyl-4-piperidyl) butane-1,2,3,4-tetracarboxylate, a reaction product of 1,2,2,6,6-pentamethyl-4-piperidol and β,β,β',β'-tetramethyl-2,4,8,10-tetraoxaspiro[5.5]undecane-3,9-diol, a reaction product of 2,2,6,6-tetramethyl-4-piperidol and β,β,β',β'-tetramethyl-2,4,8,10-tetraoxaspiro[5.5]undecane-3,9-diol, bis(1-undecanoxy-2,2,6,6-tetramethylpiperidin-4-yl) carbonate, 1,2,2,6,6-pentamethyl-4-piperidyl methacrylate, 2,2,6,6-tetramethyl-4-piperidyl methacrylate, and the like. Among them, bis(1,2,2,6,6-pentamethyl-4-piperidyl) [[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]methyl]butyl malonate, dibutylamine·1,3,5-triazine·N,N'-bis(2,2,6,6-tetramethyl-4-piperidyl)-1,6-hexamethylenediamine and N-(2,2,6,6-tetramethyl-4-piperidyl)butylamine polycondensate, poly[{6-(1,1,3,3-tetramethylbutyl)amino-1,3,5-triazine-2,4-diyl}{(2,2,6,6-tetramethyl-4-piperidyl)imino}hexamethylene{(2,2,6,6-tetramethyl-4-piperidyl)imino}], the reaction product of 1,2,2,6,6-pentamethyl-4-piperidol and β,β,β',β'-tetramethyl-2,4,8,10-tetraoxaspiro[5.5]undecane-3,9-diol, and the reaction product of 2,2,6,6-tetramethyl-4-piperidol and β,β,β',β'-tetramethyl-2,4,8,10-tetraoxaspiro[5.5]undecane-3,9-diol are preferred.

[0089] The content of the hindered amine light stabilizer may be an amount that can obtain the effect of improving the light stability. If the content is excessive, problems such as bleeding out during processing may occur. Therefore, it is preferably 5 parts by mass or less, more preferably 3 parts by mass or less, still more preferably 1 part by mass or less, even more preferably 0.8 part by mass or less, even more preferably 0.01 to 0.8 part by mass, and particularly preferably 0.01 to 0.5 part by mass, based on 100 parts by mass of the methacrylic copolymer.

[0090] --Ultraviolet Absorber-- The composition containing the methacrylic copolymer of this embodiment can contain an ultraviolet absorber. The ultraviolet absorber is not particularly limited, but it is preferably an ultraviolet absorber having a maximum absorption wavelength of 280 to 380 nm. For example, benzotriazole-based compounds, benzotriazine-based compounds, benzophenone-based compounds, oxybenzophenone-based compounds, benzoate-based compounds, phenol-based compounds, oxazole-based compounds, cyanoacrylate-based compounds, benzoxazinone-based compounds, etc. can be mentioned.

[0091] Examples of the benzotriazole-based compounds include 2,2'-methylenebis[4-(1,1,3,3-tetramethylbutyl)-6-(2H-benzotriazol-2-yl)phenol], 2-(3,5-di-tert-butyl-2-hydroxyphenyl)-5-chlorobenzotriazole, 2-(2H-benzotriazol-2-yl)-p-cresol, 2-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol, 2-benzotriazol-2-yl-4,6-di-tert-butylphenol, 2-[5-chloro(2H)-benzotriazol-2-yl]-4-methyl-6-t-butylphenol, 2-(2H-benzotriazol-2-yl)-4,6-di-t-butylphenol, 2-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol, 2-(2H-benzotriazol-2-yl)-4-methyl-6-(3,4,5,6-tetrahydrophthalimidylmethyl)phenol, the reaction product of methyl 3-(3-(2H-benzotriazol-2-yl)-5-t-butyl-4-hydroxyphenyl)propionate / polyethylene glycol 300, 2-(2H-benzotriazol-2-yl)-6-(linear and branched dodecyl)-4-methylphenol, 2-(5-methyl-2-hydroxyphenyl)benzotriazole, 2-[2-hydroxy-3,5-bis(α,α-dimethylbenzyl)phenyl]-2H-benzotriazole, 3-(2H-benzotriazol-2-yl)-5-(1,1-dimethylethyl)-4-hydroxy-C7-9 side chain and linear alkyl ester. Among these, benzotriazole compounds with a molecular weight of 400 or more are preferred. For example, in the case of commercially available products, Kemisorb (registered trademark) 2792 (manufactured by Chemipro Kasei Co., Ltd.), Adeka Stab (registered trademark) LA31 (manufactured by ADEKA CORPORATION), Tinuvin (registered trademark) 234 (manufactured by BASF), etc. can be mentioned.

[0092] Examples of benzotriazine compounds include 2-mono(hydroxyphenyl)-1,3,5-triazine compounds, 2,4-bis(hydroxyphenyl)-1,3,5-triazine compounds, and 2,4,6-tris(hydroxyphenyl)-1,3,5-triazine compounds. Specifically, 2,4-diphenyl-6-(2-hydroxy-4-methoxyphenyl)-1,3,5-triazine, 2,4-diphenyl-6-(2-hydroxy-4-ethoxyphenyl)-1,3,5-triazine, 2,4-diphenyl-(2-hydroxy-4-propoxyphenyl)-1,3,5-triazine, 2,4-diphenyl-(2-hydroxy-4-butoxyphenyl)-1,3,5-triazine, 2,4-diphenyl-6-(2-hydroxy-4-butoxyphenyl)-1,3,5-triazine, 2,4-diphenyl-6-(2-hydroxy-4-hexyloxyphenyl)-1,3,5-triazine, 2,4-diphenyl-6-(2-hydroxy-4-octyloxyphenyl)-1,3,5-triazine, 2,4-diphenyl-6-(2-hydroxy-4-dodecyloxyphenyl)-1,3,5-triazine, 2,4-diphenyl-6-(2-hydroxy-4-benzyloxyphenyl)-1,3,5-triazine, 2,4-diphenyl-6-(2-hydroxy-4-butoxyethoxy)-1,3,5-triazine, 2,4-bis(2-hydroxy-4-butoxyphenyl)-6-(2,4-dibutoxyphenyl)-1,3-5-triazine, 2,4,6-tris(2-hydroxy-4-methoxyphenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-4-ethoxyphenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-4-propoxyphenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-4-butoxyphenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-4-butoxyphenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-4-hexyloxyphenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-4-octyloxyphenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-4-dodecyloxyphenyl)-1,3,5-triazine, 2,4,6-Tris(2-hydroxy-4-benzyloxyphenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-4-ethoxyethoxyphenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-4-butoxyethoxyphenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-4-propoxyethoxyphenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-4-methoxycarbonylpropyloxyphenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-4-ethoxycarbonylethyloxyphenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-4-(1-(2-ethoxyhexyloxy)-1-oxopropan-2-yloxy)phenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-3-methyl-4-methoxyphenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-3-methyl-4-ethoxyphenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-3-methyl-4-propoxyphenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-3-methyl-4-butoxyphenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-3-methyl-4-butoxyphenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-3-methyl-4-hexyloxyphenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-3-methyl-4-octyloxyphenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-3-methyl-4-dodecyloxyphenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-3-methyl-4-benzyloxyphenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-3-methyl-4-ethoxyethoxyphenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-3-methyl-4-butoxyethoxyphenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-3-methyl-4-propoxyethoxyphenyl)-1,3,5-triazine, 2,4,Examples include 6-tris(2-hydroxy-3-methyl-4-methoxycarbonylpropyloxyphenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-3-methyl-4-ethoxycarbonylethyloxyphenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-3-methyl-4-(1-(2-ethoxyhexyloxy)-1-oxopropan-2-yloxy)phenyl)-1,3,5-triazine, etc. As the benzotriazine compound, commercially available products may be used. For example, Kemisorb 102 (manufactured by Chemipro Kasei Co., Ltd.), LA-F70 (manufactured by ADEKA Corporation), LA-46 (manufactured by ADEKA Corporation), Tinuvin 405 (manufactured by BASF), Tinuvin 460 (manufactured by BASF), Tinuvin 479 (manufactured by BASF), Tinuvin 1577FF (manufactured by BASF), etc. can be used. Among them, from the viewpoints of high compatibility with acrylic resins and excellent ultraviolet absorption characteristics, an ultraviolet absorber having a 2,4-bis(2,4-dimethylphenyl)-6-[2-hydroxy-4-(3-alkyloxy-2-hydroxypropyloxy)-5-α-cumylphenyl]-s-triazine skeleton (where "alkyloxy" means a long-chain alkyloxy group such as octyloxy, nonyloxy, decyloxy, etc.) can be more preferably used.

[0093] As the ultraviolet absorber, particularly from the viewpoints of compatibility with resins and volatility during heating, benzotriazole compounds and benzotriazine compounds having a molecular weight of 400 or more are preferable. Also, from the viewpoint of suppressing decomposition of the ultraviolet absorber itself due to heating during extrusion processing, benzotriazine compounds are particularly preferable.

[0094] Further, the melting point (Tm) of the ultraviolet absorber is preferably 80°C or higher, more preferably 100°C or higher, still more preferably 130°C or higher, and even more preferably 160°C or higher. It is preferable that the weight loss rate of the ultraviolet absorber when heated at a rate of 20 °C / min from 23 °C to 260 °C is 50% or less, more preferably 30% or less, even more preferably 15% or less, even more preferably 10% or less, and even more preferably 5% or less.

[0095] These ultraviolet absorbers may be used alone or in combination of two or more. By using two types of ultraviolet absorbers having different structures in combination, ultraviolet rays in a wide wavelength range can be absorbed.

[0096] The content of the ultraviolet absorber is not particularly limited as long as it does not inhibit heat resistance, heat and humidity resistance, thermal stability, and molding processability and exhibits the effects of the present invention. However, it is preferably 0.1 to 5 parts by mass, preferably 0.2 to 4 parts by mass or less, more preferably 0.25 to 3 parts by mass, and even more preferably 0.3 to 3 parts by mass with respect to 100 parts by mass of the methacrylic copolymer. Within this range, the balance of ultraviolet absorption performance, moldability, etc. is excellent.

[0097] --Release agent-- The composition containing the methacrylic copolymer of the present embodiment may contain a release agent. Examples of the release agent include, but are not limited to, fatty acid esters, fatty acid amides, fatty acid metal salts, hydrocarbon lubricants, alcohol lubricants, polyalkylene glycols, carboxylic acid esters, and paraffinic mineral oils such as hydrocarbons.

[0098] There is no particular limitation on the fatty acid ester that can be used as the release agent, and conventionally known ones can be used. Examples of the fatty acid ester include ester compounds of fatty acids having 12 to 32 carbon atoms such as lauric acid, palmitic acid, heptadecanoic acid, stearic acid, oleic acid, arachidic acid, behenic acid, etc. and monohydric aliphatic alcohols such as cetyl alcohol, stearyl alcohol, behenyl alcohol, etc. or polyhydric aliphatic alcohols such as glycerin, pentaerythritol, dipentaerythritol, sorbitan, etc.; composite ester compounds of fatty acids, polybasic organic acids and monohydric aliphatic alcohols or polyhydric aliphatic alcohols, etc. can be used. Examples of such fatty acid ester lubricants include cetyl palmitate, butyl stearate, stearyl stearate, stearyl citrate, glycerin monocaprylate, glycerin monocaprate, glycerin monolaurate, glycerin monopalmitate, glycerin dipalmitate, glycerin monostearate, glycerin distearate, glycerin tristearate, glycerin monooleate, glycerin dioleate, glycerin trioleate, glycerin monolinoate, glycerin monobehenate, glycerin mono 12-hydroxystearate, glycerin di 12-hydroxystearate, glycerin tri 12-hydroxystearate, glycerin diacetomonostearate, glycerin citrate fatty acid ester, pentaerythritol adipate stearate, montanic acid partial saponified ester, pentaerythritol tetrastearate, dipentaerythritol hexastearate, sorbitan tristearate, etc. These fatty acid ester lubricants can be used alone or in combination of two or more. Examples of commercially available products include, for example, the Rikemal series, Piem series, Rikestar series, Rikemaster series manufactured by Riken Vitamin Co., Ltd., the Excel series, Leodor series, Exepal series, Cocnard series manufactured by Kao Corporation. More specifically, Rikemal S-100, Rikemal H-100, Piem V-100, Rikemal B-100, Rikemal HC-100, Rikemal S-200, Piem B-200, Rikestar EW-200, Rikestar EW-400, Excel S-95, Leodor MS-50, etc. can be mentioned.

[0099] There are no particular restrictions on the fatty acid amide-based lubricants, and conventionally known ones can be used. Examples of the fatty acid amide-based lubricants include saturated fatty acid amides such as lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, hydroxystearic acid amide; unsaturated fatty acid amides such as oleic acid amide, erucic acid amide, ricinoleic acid amide; substituted amides such as N-stearyl stearic acid amide, N-oleyl oleic acid amide, N-stearyl oleic acid amide, N-oleyl stearic acid amide, N-stearyl erucic acid amide, N-oleyl palmitic acid amide; methylol amides such as methylol stearic acid amide, methylol behenic acid amide; saturated fatty acid bisamides such as methylene bis stearic acid amide, ethylene bis capric acid amide, ethylene bis lauric acid amide, ethylene bis stearic acid amide (ethylene bis stearyl amide), ethylene bis isostearic acid amide, ethylene bis hydroxystearic acid amide, ethylene bis behenic acid amide, hexamethylene bis stearic acid amide, hexamethylene bis behenic acid amide, hexamethylene bis hydroxystearic acid amide, N,N'-distearyl adipic acid amide, N,N'-distearyl sebacic acid amide; unsaturated fatty acid bisamides such as ethylene bis oleic acid amide, hexamethylene bis oleic acid amide, N,N'-dioleyl adipic acid amide, N,N'-dioleyl sebacic acid amide; aromatic bisamides such as m-xylylene bis stearic acid amide, N,N'-distearyl isophthalic acid amide, etc. These fatty acid amide-based mold release agents can be used alone or in combination of two or more kinds. Examples of commercially available products include, for example, Diamid series (manufactured by Nippon Kasei Co., Ltd.), Amide series (manufactured by Nippon Kasei Co., Ltd.), Nikka Amide series (manufactured by Nippon Kasei Co., Ltd.), Methylol Amide series, Bisamide series, Slipax series (manufactured by Nippon Kasei Co., Ltd.), Kao Wax series (manufactured by Kao Corporation), Fatty Acid Amide series (manufactured by Kao Corporation), Ethylene Bis Stearic Acid Amides (manufactured by Dainichi Chemical Industry Co., Ltd.), and the like.

[0100] The fatty acid metal salt refers to a metal salt of a higher fatty acid. For example, lithium stearate, magnesium stearate, calcium stearate, calcium laurate, calcium ricinoleate, strontium stearate, barium stearate, barium laurate, barium ricinoleate, zinc stearate, zinc laurate, zinc ricinoleate, zinc 2-ethylhexoate, lead stearate, dibasic lead stearate, lead naphthenate, 12-hydroxystearic acid calcium, 12-hydroxystearic acid lithium, etc. can be mentioned. Among them, calcium stearate, magnesium stearate, and zinc stearate are particularly preferred because the processability of the obtained transparent resin composition is excellent and the transparency is extremely excellent. Examples of commercially available products include, for example, the SZ series, SC series, SM series, SA series, etc. manufactured by Sakai Chemical Industry Co., Ltd. When using the above fatty acid metal salt, the content is preferably 0.2% by mass or less based on 100% by mass of the composition containing the methacrylic copolymer from the viewpoint of maintaining transparency. The above mold release agent may be used alone or in combination of two or more kinds.

[0101] As the mold release agent to be used, those having a decomposition start temperature of 200 °C or higher are preferred. Here, the decomposition start temperature can be measured by the 1% mass loss temperature by TGA. The content of the release agent only needs to be an amount that can achieve the effect as a release agent. If the content is excessive, problems such as bleed-out during processing and extrusion defects due to screw slippage may occur. Therefore, based on 100 parts by mass of the methacrylic copolymer, it is preferably 5 parts by mass or less, more preferably 3 parts by mass or less, still more preferably 1 part by mass or less, even more preferably 0.8 parts by mass or less, and even more preferably 0.01 to 0.8 parts by mass, particularly preferably 0.01 to 0.5 parts by mass. Adding in the amount within the above range can suppress the decrease in transparency due to the addition of the release agent, and also tends to suppress mold release failure during injection molding and sticking to the metal roll during sheet molding, so it is preferable.

[0102] --Other thermoplastic polymers-- The composition containing the methacrylic copolymer of the present embodiment can also contain other thermoplastic polymers other than the methacrylic copolymer for the purpose of adjusting the birefringence and improving the flexibility without impairing the object of the present invention. Examples of other thermoplastic polymers include polyacrylates such as polybutyl acrylate; styrene-based polymers such as polystyrene, styrene-methyl methacrylate copolymer, styrene-butyl acrylate copolymer, styrene-acrylonitrile copolymer, acrylonitrile-butadiene-styrene block copolymer; and further, for example, acrylic rubber particles having a 3-4 layer structure described in JP-A-59-202213, JP-A-63-27516, JP-A-51-129449, JP-A-52-56150, etc.; rubbery polymers disclosed in JP-B-60-17406, JP-A-8-245854; methacrylic rubber-containing graft copolymer particles obtained by multi-stage polymerization described in WO2014 / 002491; and the like. Among these, from the viewpoint of obtaining good optical properties and mechanical properties, styrene-acrylonitrile copolymers and rubber-containing graft copolymer particles having a graft part composed of a composition compatible with the methacrylic copolymer on their surface layer are preferable. The average particle diameters of the aforementioned acrylic rubber particles, methacrylic rubber-containing graft copolymer particles, and rubbery polymers are preferably from 0.03 to 1 μm, more preferably from 0.05 to 0.5 μm, from the viewpoint of enhancing the impact strength, optical properties, etc. of the molded article obtained from the composition of the present embodiment.

[0103] The content of other thermoplastic polymers is preferably from 0 to 50 parts by mass, more preferably from 0 to 25 parts by mass, when the methacrylic copolymer is 100 parts by mass.

[0104] (Method for producing a composition containing a methacrylic copolymer) Examples of the method for producing a methacrylic resin composition include a method of kneading using a kneader such as an extruder, a heating roll, a kneader, a roller mixer, a Banbury mixer, etc. Among them, kneading by an extruder is preferable in terms of productivity. The kneading temperature may follow the preferable processing temperature of the methacrylic copolymer and other polymers to be mixed, and as a guideline, it is in the range of 140 to 300 °C, preferably in the range of 180 to 280 °C. Further, it is preferable to provide a vent port to the extruder for the purpose of reducing volatile components.

[0105] The glass transition temperature (Tg), weight average molecular weight (Mw), and number average molecular weight (Mn) of the composition containing the methacrylic copolymer may be the same as those described above for the methacrylic resin.

[0106] (Molded article) By performing molding using the pellets containing the methacrylic copolymer of the present embodiment, a molded article made of a composition containing the methacrylic copolymer can be obtained.

[0107] (Method for producing a molded article) The method for manufacturing the molded article of the present embodiment includes performing a molding process using pellets containing the methacrylic copolymer of the present embodiment. For the molding process, various molding methods such as extrusion molding, injection molding, compression molding, calender molding, inflation molding, and hollow molding can be used. Among them, injection molding and injection compression molding are preferably applied from the viewpoint of productivity. Generally, the injection molding method includes: (1) an injection step of melting the resin and filling the molten resin into the cavity of a temperature-controlled mold; (2) a holding pressure step of applying pressure to the cavity until the gate is sealed, and injecting resin corresponding to the amount by which the molten resin filled in the injection step contacts the mold, cools, and shrinks; (3) a cooling step of holding the molded article until the resin is cooled after releasing the holding pressure; and (4) a step of opening the mold and taking out the cooled molded article.

[0108] At this time, as the molding temperature, based on the glass transition temperature of the composition containing the methacrylic copolymer, it is preferably in the range of Tg + 100°C to Tg + 160°C, and more preferably in the range of Tg + 110°C to Tg + 150°C. Here, the molding temperature refers to the control temperature of the band heater wound around the injection nozzle. Also, as the mold temperature, based on the glass transition temperature (Tg) of the composition containing the methacrylic copolymer, it is preferably in the range of Tg - 70°C to Tg, and more preferably in the range of Tg - 50°C to Tg - 20°C.

[0109] Also, the injection speed can be appropriately selected according to the thickness and dimensions of the injection molded article to be obtained. For example, it can be appropriately selected from the range of 200 to 1000 mm / second. Also, the pressure for holding pressure can be appropriately selected according to the shape of the injection molded article to be obtained. For example, it can be appropriately selected in the range of 30 to 120 MPa. In the case of a thin-walled molded article with a high solidification rate, the holding pressure may not be applied. Here, the pressure for holding pressure is the pressure held by the screw for further sending out the molten resin from the gate after filling the molten resin.

[0110] Injection compression molding is an injection molding method in which, at the start of injection molding, the mold is slightly opened in advance, and after filling the molten resin into the mold at high speed and low pressure, the mold clamping pressure is increased at high speed, and a compression holding pressure process for uniformly holding pressure on the entire surface of the resin is added. This makes it possible to mold a molded body with excellent surface characteristics and optical characteristics. When attempting to obtain an injection molded body that is thinner, for example, with a thickness of less than 1 mm and a diagonal dimension exceeding 100 mm, it is particularly preferable to adopt injection compression molding because a molded body with superior optical characteristics and color tone can be obtained.

[0111] In addition, when using an injection molded body obtained using pellets of the composition containing the above methacrylic copolymer as a light guide plate, those having fine irregularities embossed on their surfaces are also included. By providing such fine irregularities, it becomes unnecessary to separately provide a reflective layer by printing or the like, which is preferable. The fine irregularities are not particularly limited, but include irregularities with distinct structural units such as rectangular parallelepipeds, cylinders, elliptical cylinders, triangular prisms, spherical surfaces, aspherical surfaces, etc., and irregularity shapes such as satin finish or hairline finish, but with indistinct structural units or combinations thereof, and further irregularities with distinct structural units but with varying shapes, especially sizes. Examples of the shape of the irregularities include a height or recess of 0.1 to 500 μm, and examples of the pitch distance between the irregularities include 10 to 1000 μm.

[0112] Various molded bodies using the pellets of the methacrylic copolymer and the composition containing the copolymer of this embodiment can further be subjected to surface functionalization treatments such as antireflection treatment, transparent conductive treatment, electromagnetic wave shielding treatment, gas barrier treatment, etc.

[0113] (Applications of the Molded Body) The molded body obtained from the pellets of this embodiment uses N-phenylmaleimide with reduced impurities such as PMA and APSI as a raw material, so it has excellent heat resistance and coloring during molding is suppressed while maintaining transparency. Therefore, it can be suitably used for applications such as optical members in household goods, OA equipment, AV equipment, battery electrical components, lighting equipment, automobiles, etc. As optical members for household goods, OA equipment, AV equipment, battery and electrical components, lighting equipment, etc., for example, there are light guide plates, display front panels, touch panels used for displays of smartphones, PDAs, tablet PCs, liquid crystal TVs, etc., and further, lenses for smartphone and tablet PC cameras, etc., and optical lens components such as head-mounted displays and liquid crystal projectors, for example, prism elements, waveguides, lenses, especially small and thin and uneven-shaped optical lenses, optical fibers, coating materials for optical fibers, lenses, Fresnel lenses, phase provided with a microlens array, optical cover components, etc. As optical members for automobiles, etc., there are light guide plates for in-vehicle displays; front panels for in-vehicle meter panels,; front panels for car navigation, combiners, optical cover components, etc., optical components for head-up displays; in-vehicle camera lenses, light guide rods, etc. In addition to the above, it can also be preferably used for components for digital signage display devices that flow information to thin displays connected to a network for the purpose of advertising, etc. at places such as camera focusing plates, outdoors, storefronts, public institutions, transportation facilities, etc.

Examples

[0114] Hereinafter, the content of the present invention will be specifically described with reference to Examples and Comparative Examples. Note that the present invention is not limited to the following Examples.

[0115] <1. Measurement of impurity content in PMI> The PMI in the Examples and Comparative Examples was dissolved in acetonitrile to prepare a 4 mass% solution, and measured under the following apparatus and conditions. · Measuring apparatus: High Performance Liquid Chromatography (LC Ultra3000 LTQ XL) manufactured by Thermо · Measurement conditions: Column: kinetex 2.6XB C-18 5.0×2.1mm, Column temperature: 40°C, flow rate: 0.2 mL / min, injection volume: 10 μL, Detector: PMA: UV detector (wavelength: 254 nm), APSI: MS (ionization: ESI+, scan range: m / z = 50 - 1000), Mobile phase: 0.1 mass% aqueous formic acid solution as A, 0.1 mass% formic acid acetonitrile solution as B, and the gradient conditions described in Table 1 below were used.

[0116]

Table 1

[0117] <2. Measurement of polymerization conversion rate> A part of the polymerization solution in the examples and comparative examples was collected. The amount of monomer remaining in this polymerization solution sample was determined by dissolving the sample in chloroform to prepare a 5 mass% solution, adding n-decane as an internal standard substance, and measuring the monomer concentration remaining in the sample using gas chromatography (GC-2010 manufactured by Shimadzu Corporation). The total mass (a) of the monomer remaining in the polymerization solution was obtained. Then, from this total mass (a), the total mass (b) assuming that all the monomers added up to the time of sample collection remained in the polymerization solution, and the total mass (c) of the monomers added until the end of the polymerization step, the polymerization conversion rate (%) was calculated using the formula (b - a) / c × 100.

[0118] <3. Analysis of structural units> 1 1H-NMR measurement and 13 13C-NMR measurement were used to identify the structural units of the produced methacrylic copolymer and calculate their abundances. 1 1H-NMR measurement and 13 13C-NMR measurement conditions are as follows. · Measuring instrument: DPX-400 manufactured by Bruker · Measuring solvent: CDCl 3 or DMSO-d 6 · Measuring temperature: 40 °C

[0119] <4. Measurement of molecular weight and molecular weight distribution> The weight average molecular weight (Mw) and number average molecular weight (Mn) of the methacrylic copolymers produced in the Examples and Comparative Examples described below were measured under the following apparatus and conditions. · Measuring apparatus: Gel Permeation Chromatography (HLC-8320GPC) manufactured by Tosoh Corporation · Measuring conditions: Column: One TSKguardcolumn SuperH-H, two TSKgel SuperHM-M, and one TSKgel SuperH2500 were connected in series and used. Column temperature: 40 °C Developing solvent: Tetrahydrofuran, Flow rate: 0.6 mL / min. As an internal standard, 2,6-di-t-butyl-4-methylphenol (BHT) was added at 0.1 g / L. Detector: RI (Differential Refractometer) detector, Detection sensitivity: 3.0 mV / min Sample: 0.02 g of methacrylic copolymer or a 20 mL solution of methacrylic copolymer in tetrahydrofuran. Injection volume: 10 μL Calibration curve standard sample: Ten types of polymethyl methacrylate (manufactured by Polymer Laboratories; PMMA Calibration Kit M-M-10) with known monodisperse weight peak molecular weights and different molecular weights were used. Weight peak molecular weight (Mp) Standard sample 1 1,916,000 Standard sample 2 625,500 Standard sample 3 298,900 Standard sample 4 138,600 Standard sample 5 60,150 Standard sample 6 27,600 Standard sample 7 10,290 Standard sample 8 5,000 Standard sample 9 2,810 Standard sample 10 850 Under the above conditions, the RI detection intensity was measured with respect to the elution time of the methacrylic copolymer. Based on the calibration curve obtained by measuring the above calibration curve standard sample, the weight average molecular weight (Mw) and number average molecular weight (Mn) of the methacrylic copolymer were determined.

[0120] <5. Glass transition temperature> In accordance with JIS-K7121, the glass transition temperature (Tg) (°C) of the methacrylic copolymer was measured. First, four samples (four locations), each approximately 10 mg, were cut out from the sample conditioned (left to stand at 23°C for one week) under standard conditions (23°C, 65% RH). Next, a differential scanning calorimeter (Diamond DSC manufactured by PerkinElmer Japan Co., Ltd.) was used under the condition of a nitrogen gas flow rate of 25 mL / min. Here, the temperature was raised from room temperature (23°C) to 200°C at 10°C / min (first heating), held at 200°C for 5 minutes to completely melt the sample, then cooled from 200°C to 40°C at 10°C / min, held at 40°C for 5 minutes, and further heated again at the above heating conditions (second heating). Among the DSC curves drawn during the second heating, the intersection point (midpoint glass transition temperature) between the stepped change part curve during the second heating and a straight line equidistant in the vertical axis direction from each baseline extension line was measured as the glass transition temperature (Tg) (°C). Four measurements were taken for each sample, and the arithmetic mean (rounded off to the nearest decimal place) of the four points was used as the measured value.

[0121] <6. Measurement of the composition distribution of structural units> For the methacrylic copolymers obtained in the examples and comparative examples, molecular weight fractionation was performed using the following apparatus and conditions. · Fractionation apparatus: LC-908 manufactured by Nippon Analytical Industry Co., Ltd. · Fractionation conditions: Column: SHODEX K-2004 Eluent: Chloroform, flow rate: 3 mL / min Detector: UV detector (254 nm) Sample: 3 mass% chloroform solution Fractionation method: 3 mL of the sample was injected, and fractions were collected at 1-minute intervals for an elution time of 18 - 43 minutes. The fractionation operation was repeated three times. The composition ratio of the structural units was determined for the samples selected from the obtained fractions in accordance with the aforementioned <3. Analysis of structural units>, and the molecular weight distribution was measured in accordance with <4. Measurement of molecular weight and molecular weight distribution>. The peak top molecular weight (Mp) was determined from the position of the peak apex.

[0122] <7. Production of Molded Body> Using the composition pellets containing the methacrylic copolymer obtained in the examples, an injection molding machine (AUTO SHOT C Series MODEL 15A, manufactured by FANUC Corporation) was used to obtain strip-shaped molded pieces as shown in Fig. 1. Injection molding was carried out using a strip-shaped mold with a side gate having a thickness of 4 mm, a width of 10 mm, and a length of 80 mm. First, with the cylinder temperature set at 270 °C, the mold temperature at 90 °C, and the cooling time at 600 seconds, the minimum injection pressure (short shot point, SSP) at which the resin was completely filled into the mold while varying the injection pressure was determined. Next, the strip-shaped molded pieces were obtained by setting the injection pressure at SSP + 50 kgf / cm 2 and performing injection molding.

[0123] <8. Measurement of Color Tone of Molded Body> The obtained strip-shaped molded pieces were used to measure the spectral transmittance (%) and yellowness index YI at a wavelength of 400 to 700 nm with a long optical path of 80 mm using a long optical path spectroscopic transmittance colorimeter ASA1 manufactured by Nippon Denshoku Industries Co., Ltd. 成形体 Similar to the color tone measurement of the pellets, the yellowness index YI 成形体 was calculated from the tristimulus values X, Y, and Z obtained from the measurement according to JIS K7105 using the calculation formula of YI 成形体 = 100(1.28X - 1.06Z) / Y.

[0124] [Raw Materials] The raw materials used in the production examples described below are shown below. [Monomers] · Methyl methacrylate: manufactured by Asahi Kasei Corporation · N-Phenylmaleimide (PMI): manufactured by Nippon Shokubai Co., Ltd. · N-Cyclohexylmaleimide (CMI): manufactured by Nippon Shokubai Co., Ltd. [Polymerization Initiator] · 1,1-Di(t-butylperoxy)cyclohexane: "Perhexa C" manufactured by NOF Corporation [Chain Transfer Agent] · n-Octyl mercaptan: manufactured by Kao Corporation

[0125] [Example 1] (Production of PMI with Reduced PMA and APSI Contents) To a 50 mL screw tube (manufactured by AS ONE Corporation, model number: No. 7) equipped with a stir bar (manufactured by AS ONE Corporation, model number: C 5×15), 3.5 g of metaxylene (manufactured by Mitsubishi Gas Chemical Company, hereinafter referred to as mXy) and 0.30 g of N-phenylmaleimide (manufactured by Nippon Shokubai Co., Ltd., hereinafter referred to as PMI) were weighed and added, and stirred at 18 °C for 20 minutes (150 rpm) to dissolve PMI in mXy to obtain a PMI suspension solution. Next, the PMI suspension solution was filtered at 18 °C using a 6 mL plastic syringe (manufactured by AS ONE Corporation, product number: 2-4031-02) equipped with a polytetrafluoroethylene (PTFE) syringe filter (manufactured by Advantec Toyo Co., Ltd., 13JP020AN, pore size 0.2 μm) to obtain 3.8 g of a solution layer. From this solution layer, the temperature was raised to 60 °C under a reduced pressure of 4 kPa using an evaporator (manufactured by Tokyo Rikakikai Co., Ltd., model number: N-1300E) to distill off the mXy solvent, and the remaining yellow solid was placed in a dryer (manufactured by AS ONE Corporation, model number: AVO-200SB-D) and dried under reduced pressure at 60 °C for 2 hours. Finally, 0.29 g of a purified PMI yellow solid was obtained. The amounts of PMA and APSI contained in the obtained purified PMI are shown in Table 2 below.

[0126] (Production of Methacrylic Copolymer Using PMI as a Raw Material and Molded Article Containing the Same) 358.6 kg of methyl methacrylate (hereinafter referred to as MMA), 29.4 kg of purified PMI, 67.7 kg of N-cyclohexylmaleimide (hereinafter referred to as CMI), 0.77 kg of n-octyl mercaptan as a chain transfer agent, and 224.3 kg of mXy were weighed and added to a 1.25 m 3 reactor equipped with a temperature control device by a jacket and a stirring blade, and stirred to obtain a mixed monomer solution. Next, 88.0 kg of MMA, 6.3 kg of purified PMI, and 142.4 kg of mXy were weighed and added to Tank 1 and stirred to obtain a supplementary mixed monomer solution. The content liquid of the reactor was bubbled with nitrogen at a rate of 30 L / min for 1 hour, and the liquid in Tank 1 was bubbled with nitrogen at a rate of 10 L / min for 30 minutes to remove dissolved oxygen. Thereafter, steam was blown into the jacket to raise the solution temperature in the reactor to 115 °C, and while stirring at 50 rpm, a polymerization initiator solution prepared by dissolving 0.487 kg of 1,1 - di(t - butylperoxy)cyclohexane in 1.888 kg of mXy was added at a rate of 1.0 kg / hour to initiate polymerization. During polymerization, the solution temperature in the reactor was controlled at 115 ± 2 °C by temperature adjustment with the jacket. Thirty minutes after the start of polymerization, the addition rate of the polymerization initiator solution was decreased to 0.5 kg / hour. Also, from 1 hour after the start of polymerization to 4 hours, the additional mixed monomer solution from Tank 1 was added at a constant rate in its entirety. Furthermore, the addition rate of the polymerization initiator solution was decreased to 0.25 kg / hour 3.5 hours after the start of polymerization, and the addition was stopped 5 hours after the start of polymerization. After 12 hours had elapsed since the start of polymerization, a polymer solution containing a methacrylic copolymer was obtained. Samples of the polymer solution were taken 2 hours and 12 hours after the start of polymerization, and the polymerization conversion rate was analyzed from the remaining monomer concentration. As a result, the polymerization conversion rate 2 hours after the start was 78.9% for MMA, 77.3% for PMI, and 70.4% for CMI, and 97.9% for MMA, 99.4% for PMI, and 99.3% for CMI 12 hours after the start. When the monomers added after 2 hours from the start of polymerization were taken into account and the polymerization conversion rate 2 hours after the start was converted to the consumption rate with respect to the total amount of each monomer added until the end of polymerization, it was 67.2% for MMA, 67.1% for PMI, and 70.4% for CMI. This polymer solution was fed to a concentration device consisting of a tubular heat exchanger and a vaporization tank pre - heated to 250 °C for devolatilization. The degree of vacuum in the vaporization tank was set under the condition of 10 - 15 Torr. The resin flowing down from the vaporization tank was discharged by a gear pump, extruded from a strand die, pelletized after water cooling, and pellets of a composition containing a methacrylic copolymer were obtained. When the composition of the obtained pellets was confirmed, the structural units derived from the MMA, PMI, and CMI monomers were 81.0% by mass, 6.6% by mass, and 12.4% by mass, respectively. Also, the weight-average molecular weight was 108,000, and Mw / Mn was 2.04. The glass transition temperature was 134°C. Also, the measurement results of the composition distribution of the structural units were Mp: 253,000 (MMA: 81.4% by mass, PMI: 6.5% by mass, CMI: 12.1% by mass), Mp: 176,000 (MMA: 81.1% by mass, PMI: 6.6% by mass, CMI: 12.3% by mass), Mp: 111,000 (MMA: 80.9% by mass, PMI: 6.7% by mass, CMI: 12.4% by mass), Mp: 88,000 (MMA: 80.8% by mass, PMI: 6.7% by mass, CMI: 12.5% by mass), and Mp: 48,000 (MMA: 80.4% by mass, PMI: 6.8% by mass, CMI: 12.8% by mass). Also, the pellets were injection molded into the above-mentioned strip-shaped molded pieces to obtain a molded body. As a result of performing color tone measurement on the molded body with a long optical path of 80 mm, the yellowness index YI 成形体 was 32.9. In the case of the molded body using the unpurified PMI of Comparative Example 1 described later as a raw material, it was 37.6 (the average value of two measurements each), and ΔYI 成形体 = 37.6 - 32.9 = 4.7, and by reducing the impurities PMA and APSI in PMI, ΔYI 成形体 was improved by 4.7.

[0127] [Example 2] As a raw material for producing the methacrylic copolymer, polymerization was carried out using the purified PMI (the contents of impurities PMA and APSI are shown in Table 2) obtained by filtering the PMI suspension solution of Example 1 at 40°C. Under other conditions, a molded body was obtained by the same procedure as in Example 1.

[0128] [Example 3] As a raw material for producing the methacrylic copolymer, polymerization was carried out using the purified PMI (the contents of impurities PMA and APSI are shown in Table 2) obtained by filtering the PMI suspension solution of Example 1 at 60°C. Under other conditions, a molded body was obtained by the same procedure as in Example 1.

[0129] [Comparative Example 1] As a raw material for producing the methacrylic copolymer, polymerization was carried out without purifying the PMI used in Example 1 (the contents of impurities PMA and APSI are shown in Table 2). Under other conditions, a molded body was obtained by the same procedure as in Example 1.

[0130] [Comparative Example 2] As a raw material for producing the methacrylic copolymer, the PMI used in Example 1 was stirred at 60 °C for 20 minutes (150 rpm), and a PMI suspension solution in which the PMI was dissolved in mXy was filtered at 60 °C to obtain purified PMI (the contents of impurities PMA and APSI are shown in Table 2), and polymerization was carried out using this. Under other conditions, a molded body was obtained by the same procedure as in Example 1.

[0131] [Comparative Example 3] As a raw material for producing the methacrylic copolymer, APSI was added to the purified PMI obtained in Example 1, and polymerization was carried out using PMI prepared so that the APSI content was 0.03% by mass (the contents of impurities PMA and APSI are shown in Table 2). Under other conditions, a molded body was obtained by the same procedure as in Example 1.

[0132] [Table 2]

[0133] (Evaluation of mechanical properties) Furthermore, regarding the injection-molded pieces of the comparative example data and the example data, when the mechanical properties were evaluated from the measurements of the tensile test and the bending test, no difference in mechanical properties was found due to the impurity content in the PMI.

[0134] (Evaluation of thermal properties) Regarding the thermal properties of each of the injection-molded pieces of the comparative example data and the example data, using a TG-DTA apparatus manufactured by Shimadzu Corporation (product name: DTG-60A) and an aluminum krypton cell, each pellet was heated at a rate of 10 °C / min in a nitrogen gas stream. The thermal decomposition (TGA) of each was measured, and when the thermal decomposition start temperatures were compared from the tangent intersection points of the TGA curves, no difference in the thermal decomposition start temperature was found due to the impurity content in the PMI.

[0135] The pellets of the composition containing a methacrylic copolymer using PMI with reduced impurity PMA and APSI contents as a raw material in this embodiment have high heat resistance, the coloring of the molded body obtained by (injection) molding the pellets is suppressed, and since it has a higher transmittance, the molded body can be suitably used for optical component applications such as light guide plates, light guide plates for in-vehicle displays; in-vehicle meter panels,; front panels of car navigation systems, combiners, optical cover parts, etc., optical components for head-up displays, etc., in automotive parts applications.

Industrial Applicability

[0136] According to the method of the present invention, N-phenylmaleimide is used as at least one component of the copolymerizable monomer and a copolymer obtained by using it can be efficiently produced, which has reduced yellowness and improved quality (appearance, heat resistance, strength). In addition, a molded body containing a methacrylic copolymer using the PMI of the present invention as a raw material has high heat resistance, low yellowness, and excellent transparency, so it can be suitably used for applications such as optical members in household goods, OA equipment, AV equipment, parts for battery electrical equipment, lighting equipment, automobiles, etc. Examples of optical members in household goods, OA equipment, AV equipment, parts for battery electrical equipment, lighting equipment, etc. include, for example, light guide plates, display front panels, touch panels used in displays of smartphones, PDAs, tablet PCs, liquid crystal TVs, etc., and further, lenses for smartphone and tablet PC cameras, etc., and optical lens parts such as head-mounted displays and liquid crystal projectors, for example, prism elements, waveguides, lenses, especially small and thin and uneven-shaped optical lenses, optical fibers, coating materials for optical fibers, lenses, Fresnel lenses, phase plates equipped with microlens arrays, optical cover parts, etc. Examples of optical members in automobiles, etc. include light guide plates for in-vehicle displays, in-vehicle meter panels, front panels of car navigation systems, combiners, optical cover parts, etc., optical components for head-up displays; in-vehicle camera lenses, light guide rods, etc. In addition to the above, it can also be preferably used for components for a display device for digital signage that transmits information to a thin display connected to a network for the purpose of advertising, promotion, etc. at places such as a camera focusing screen, outdoors, storefronts, public institutions, and transportation facilities.

Claims

1. An N-phenylmaleimide (PMI) compound containing 0.06% by mass or less of N-phenylmaleamic acid (PMA) and 0.01% by mass or less of 2-anilino-N-phenylsuccinimide (APSI).

2. A copolymer using the N-phenylmaleimide compound according to claim 1 as a raw material.

3. A methacrylic copolymer using the N-phenylmaleimide compound according to claim 1 as a raw material.

4. A molded article comprising the copolymer according to claim 2 or 3.

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