Composition, polymer, cured product, molded body, and method for producing polymethyl methacrylate

Abstract

The present invention addresses the problem of providing: a composition having excellent storage stability; a polymer, a cured product, and a molded body obtained by using the composition; and a method for producing polymethyl methacrylate using the composition.　The present invention pertains to a composition which contains methyl methacrylate and toluene, and in which the concentration of toluene is more than 0 mass ppm but less than 1000 mass ppm of the entire composition.

Description

Composition, polymer, cured product, molded product, and method for producing polymethyl methacrylate

[0001] The present disclosure relates to a composition, a polymer, a cured product, a molded article, and a method for producing polymethyl methacrylate.

[0002] Polymethyl(meth)acrylate obtained by polymerizing methyl(meth)acrylate is used in various fields as a resin material with excellent transparency and weather resistance. In recent years, with the rise in resource prices and growing awareness of environmental issues, products (molded articles) containing polymethyl(meth)acrylate used for various applications as described above are being collected and recycled.

[0003] Methods for recycling polymethyl(meth)acrylate include, for example, material recycling, in which recovered molded bodies are subjected to a molding process again to produce new molded bodies; chemical recycling, in which recovered molded bodies are heat-treated to thermally decompose (depolymerize) the polymethyl(meth)acrylate to recover methyl (meth)acrylate, and new molded bodies are produced using the recovered methyl (meth)acrylate (sometimes referred to as recycled MMA or recycled MA); and thermal recycling, in which recovered molded bodies are burned as fuel and the combustion energy is used directly as a heat source and further used to generate electricity.

[0004] Furthermore, in response to the recent diversification of applications of polymethyl(meth)acrylate, techniques for improving the quality of polymethyl(meth)acrylate have been investigated. For example, as a polymerization apparatus suitable for obtaining high-quality polymethyl(meth)acrylate, a polymerization apparatus that suppresses the formation of gelled products in a reaction vessel in which raw material monomers and a polymerization initiator are reacted has been proposed (see Patent Document 1).

[0005] JP 2012-102190 A

[0006] In addition to improving the polymerization process of raw material monomers as described in Patent Document 1, measures to improve the quality of polymethyl(meth)acrylate include measures to suppress deterioration in quality of raw material monomers during storage. In view of the above circumstances, an object of one embodiment of the present disclosure is to provide a composition that has excellent storage stability, particularly storage stability when stored for a long period of time, a polymer, a cured product, and a molded article obtained using this composition, and a method for producing polymethyl methacrylate using this composition.

[0007] Means for solving the above problems include the following embodiments. <1> A composition containing methyl methacrylate and toluene, wherein the toluene concentration is more than 0 ppm by mass and less than 1,000 ppm by mass of the total composition. <2> The composition according to <1>, wherein the methyl methacrylate content is 85% by mass or more of the total composition. <3> The composition according to <1> or <2>, wherein the methyl methacrylate content is 90% by mass or more of the total composition. <4> The composition according to any one of <1> to <3>, wherein the toluene concentration is 5 ppm by mass to 700 ppm by mass of the total composition. <5> The composition according to any one of <1> to <4>, wherein the toluene concentration is 100 ppm by mass to 600 ppm by mass of the total composition. <6> The composition according to any one of <1> to <5>, wherein the methyl methacrylate includes recycled methyl methacrylate or bio-derived methyl methacrylate. <7> The composition according to any one of <1> to <6>, further comprising a (meth)acrylic acid ester other than methyl methacrylate. <8> The composition according to any one of <1> to <7>, further comprising a polymer comprising structural units derived from methyl methacrylate. <9> A polymer comprising structural units derived from methyl methacrylate, contained in the composition according to any one of <1> to <8>. <10> A molded article comprising the polymer according to <9>. <11> A cured product of the composition according to any one of <1> to <8>. <12> A molded article comprising the cured product according to <11>. <13> A method for producing polymethyl methacrylate, comprising a step of polymerizing methyl methacrylate contained in the composition according to any one of <1> to <8>.

[0008] According to one embodiment of the present disclosure, there are provided a composition having excellent storage stability, particularly excellent storage stability when stored for a long period of time, a polymer, a cured product, and a molded article obtained using this composition, and a method for producing polymethyl methacrylate using this composition.

[0009] 1 is a graph showing the relationship between the toluene concentration and the average transmittance of the compositions prepared in the examples.

[0010] Hereinafter, embodiments of the present invention will be described. However, the present invention is not limited to the following embodiments. In this specification, numerical ranges indicated using "to" include the numerical values ​​before and after "to" as the minimum and maximum values, respectively. In numerical ranges described in stages in this specification, the upper or lower limit value described in one numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. Furthermore, in numerical ranges described in this specification, the upper or lower limit value of that numerical range may be replaced with a value shown in an example.

[0011] <Composition> The composition of the present disclosure contains methyl methacrylate and toluene, and the toluene concentration is greater than 0 ppm by mass and less than 1000 ppm by mass in the total composition. The composition of the present disclosure may be in a liquid form or in a solid form such as pellets. In the case of a liquid form, it may be, for example, a monomer composition or may contain a polymer of a monomer, such as a syrup. As shown in the examples described below, the composition of the present disclosure has excellent storage stability.

[0012] (Methyl methacrylate) The composition of the present disclosure contains methyl methacrylate. In this disclosure, "methyl methacrylate" refers to methyl methacrylate that is essentially free of impurities such as by-products generated during the synthesis of methyl methacrylate. However, the methyl methacrylate in this disclosure is not limited to this, provided that the purpose of the invention is not impaired. In other words, "methyl methacrylate" may contain impurities that cannot be completely removed by conventional purification methods, or may contain impurities at a level that cannot be detected by conventional detection methods.

[0013] The content of methyl methacrylate in the composition is not particularly limited and can be selected depending on the application of polymethyl methacrylate obtained using the composition. The content of methyl methacrylate may be, for example, 85% by mass or more, 90% by mass or more, 95% by mass or more, or 99% by mass or more of the total composition. A content of methyl methacrylate in the composition within the above range is preferable from the viewpoint of at least heat resistance or transparency (light transmittance) of a polymer obtained by polymerizing the composition and a molded article containing the same.

[0014] The methyl methacrylate contained in the composition may be synthesized by a known synthesis method. The synthesis method is not particularly limited, and may be the ACH method, the C4 direct acid method, or the alpha method.

[0015] The methyl methacrylate contained in the composition may include recycled methyl methacrylate. In this disclosure, recycled methyl methacrylate refers to methyl methacrylate obtained by depolymerization of polymethyl methacrylate (a reaction in which a polymer decomposes to produce monomers). Depolymerization of polymethyl methacrylate can be achieved, for example, by heat-treating polymethyl methacrylate. The source of polymethyl methacrylate, which is the raw material for recycled methyl methacrylate, is not particularly limited as long as methyl methacrylate can be recovered. For example, the source of polymethyl methacrylate may be a molded product containing polymethyl methacrylate.

[0016] The methyl methacrylate contained in the composition may include bio-derived methyl methacrylate. In the present disclosure, bio-derived methyl methacrylate refers to methyl methacrylate synthesized from a biologically derived raw material. The biologically derived raw material may be a plant-derived raw material or an animal-derived raw material, and is preferably a raw material derived from vegetable oil.

[0017] (Toluene) The composition of the present disclosure contains toluene. The concentration of toluene contained in the composition is more than 0 ppm by mass and less than 1000 ppm by mass of the entire composition. From the viewpoint of long-term storage stability of the composition, the concentration of toluene contained in the composition is preferably 5 ppm by mass or more, more preferably 50 ppm by mass or more, and even more preferably 100 ppm by mass or more of the entire composition. From the viewpoint of optical stability of the composition, the concentration of toluene contained in the composition is preferably 700 ppm by mass or less, more preferably 600 ppm by mass or less, even more preferably 500 ppm by mass or less, particularly preferably 400 ppm by mass or less, and particularly preferably 300 ppm by mass or less of the entire composition.

[0018] If necessary, the composition may contain a component other than methyl methacrylate and toluene, for example, a (meth)acrylic acid ester other than methyl methacrylate, a polymer containing a structural unit derived from methyl methacrylate, a low-content component, or an additive, as described below.

[0019] ((Meth)acrylic acid ester) In addition to methyl methacrylate, the composition may contain a (meth)acrylic acid ester other than methyl methacrylate (hereinafter simply referred to as a (meth)acrylic acid ester). Specific examples of the (meth)acrylic acid ester include methyl acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, sec-butyl (meth)acrylate, tert-butyl (meth)acrylate, cyclohexyl (meth)acrylate, benzyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, and cyclopentanyl (meth)acrylate. Among these, methyl acrylate or ethyl acrylate is preferred, and methyl acrylate is more preferred. These may be used alone or in combination of two or more. In the present disclosure, the term "(meth)acrylic acid ester" indicates that the compound may be an acrylic acid ester or a methacrylic acid ester. The (meth)acrylic acid ester may be contained in the composition as a by-product produced during the production of methyl methacrylate or during the regeneration treatment of polymethyl methacrylate, or may be intentionally mixed into the composition.

[0020] When the composition contains a (meth)acrylic acid ester, the concentration thereof is preferably 50,000 ppm by mass or less, more preferably 40,000 ppm by mass or less, and even more preferably 30,000 ppm by mass or less, based on the total composition. When the composition contains another (meth)acrylic acid ester, the concentration thereof may be 1 ppm by mass or more, 2 ppm by mass or more, or 5 ppm by mass or more, based on the total composition.

[0021] The composition may contain, in addition to methyl methacrylate, a polymer containing structural units derived from methyl methacrylate. This polymer may be a homopolymer of methyl methacrylate or a copolymer of methyl methacrylate with another (meth)acrylic acid ester polymerizable with methyl methacrylate. Examples of the other (meth)acrylic acid ester polymerizable with methyl methacrylate include the same as those described above.

[0022] (Low Content Component) The composition may contain a low content component other than toluene. The low content component may be contained in the composition as a by-product generated during the production of methyl methacrylate or the regeneration process of polymethyl methacrylate. In the present disclosure, the low content component means a component contained in the composition at a concentration of less than 1000 ppm by mass.

[0023] Examples of the low content component other than toluene that may be contained in the composition include carboxylic acid esters, aromatic hydrocarbon compounds, aliphatic hydrocarbon compounds, alcohols, butyl acrylate, etc. The low content component other than toluene contained in the composition may be one type only or two or more types.

[0024] Specific examples of carboxylic acid esters include methyl isobutyrate, methyl propionate, methyl 2,4-dimethyl-4-pentenoate, methyl 2-methyl-3-butenoate, methyl tiglate, methyl 3-methyl-3-butenoate, methyl 3-methyl-2-butenoate, dimethyl itaconate, and dimethyl 2-methyl-5-methylenehexanedioate. Specific examples of aromatic hydrocarbon compounds include styrene. Specific examples of aliphatic hydrocarbon compounds include 1-octene and 1-octadecene.

[0025] When the composition contains low-content components other than toluene, the concentration of each low-content component is preferably 700 ppm by mass or less relative to the total composition, and may be 1 ppm by mass or more, 2 ppm by mass or more, or 5 ppm by mass or more relative to the total composition.

[0026] (Additives) The composition may contain additives as needed. Specific examples of additives include a release agent, a polymerization regulator, a polymerization initiator, an ultraviolet absorber, and a colorant. The composition may contain one or more additives.

[0027] Examples of the release agent that can be contained in the composition include higher fatty acid esters, higher fatty alcohols, higher fatty acids, higher fatty acid amides, higher fatty acid metal salts, and fatty acid derivatives. Specific examples of the release agent include sodium di-(2-ethylhexyl)sulfosuccinate, stearyl alcohol, methyl stearate, and stearic acid amide.

[0028] The composition may contain one or more types of release agents. The content of the release agent in the composition may be, for example, 0.01% by mass to 1.0% by mass of the total composition.

[0029] As the polymerization regulator (an additive that regulates the polymerization rate in a polymerization reaction) that may be contained in the composition, any suitable polymerization regulator known in the art can be used. Examples of such polymerization regulators that can be used include compounds that can regulate the polymerization rate in a direction that slows down the polymerization rate. Specific examples of polymerization regulators include mercaptan compounds such as n-butyl mercaptan and n-octyl mercaptan, terpenoid compounds such as limonene, myrcene, α-terpinene, β-terpinene, γ-terpinene, terpinolene, β-pinene, and α-pinene, and α-methylstyrene dimer.

[0030] The composition may contain one or more polymerization regulators, and the content of the polymerization regulator in the composition may be, for example, 0.001% by mass to 0.5% by mass of the total composition.

[0031] The polymerization initiator that the composition may contain includes a radical polymerization initiator, a diacyl peroxide initiator, a dialkyl peroxide initiator, a peroxyester initiator, a percarbonate initiator, and a peroxyketal initiator.

[0032] Specific examples of radical polymerization initiators include azo compounds such as 1,1′-azobis(cyclohexane-1-carbonitrile), 2,2′-azobis(2,4,4-trimethylpentene), 2,2′-azobis(2-methylpropane), 2-cyano-2-propylazoformamide, 2,2′-azobis(2-hydroxymethylpropionate), 2,2′-azobis(2-methylbutyronitrile), 2,2′-azobisisobutyronitrile, 2,2′-azobis[2-(2-imidazolin-2-yl)propane], and dimethyl 2,2′-azobis(2-methylpropionate).

[0033] Specific examples of diacyl peroxide initiators and dialkyl peroxide initiators include dicumyl peroxide, tert-butylcumyl peroxide, di-tert-butyl peroxide, benzoyl peroxide, and lauroyl peroxide.

[0034] Specific examples of peroxyester initiators include tert-butylperoxy-3,3,5-trimethylhexanoate, tert-butylperoxylaurate, tert-butylperoxyisobutyrate, tert-butylperoxyacetate, di-tert-butylperoxyhexahydroterephthalate, di-tert-butylperoxyazelate, tert-butylperoxy-2-ethylhexanoate, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, and tert-amylperoxy-2-ethylhexanoate.

[0035] Specific examples of percarbonate initiators include tert-butylperoxyallyl carbonate and tert-butylperoxyisopropyl carbonate.

[0036] Specific examples of peroxyketal initiators include 1,1-di-tert-butylperoxycyclohexane, 1,1-di-tert-butylperoxy-3,3,5-trimethylcyclohexane, and 1,1-di-tert-hexylperoxy-3,3,5-trimethylcyclohexane.

[0037] The composition may contain one or more polymerization initiators, and the content of the polymerization initiator in the composition may be, for example, 0.01% by mass to 5% by mass of the total composition.

[0038] Examples of UV absorbers that the composition may contain include benzophenone UV absorbers, cyanoacrylate UV absorbers, benzotriazole UV absorbers, malonic acid ester UV absorbers, and oxalanilide UV absorbers.

[0039] Specific examples of ultraviolet absorbers include 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-hydroxy-4-n-octylbenzophenone, 2-(3-tert-butyl-2-hydroxy-5-methylphenyl)-5-chlorobenzotriazole, 2-(2-hydroxy-3,5-di-tert-pentylphenyl)benzotriazole, and 2,4-di-tert-butylphenyl-3,5-di-tert-butyl-4-hydroxybenzoate.

[0040] The composition may contain one or more types of ultraviolet absorbers. The content of the ultraviolet absorbers in the composition may be, for example, 0.001% by mass to 1% by mass of the total composition.

[0041] Colorants that the composition may contain include perylene dyes, perinone dyes, pyrazolone dyes, methine dyes, coumarin dyes, quinophthalone dyes, quinoline dyes, anthraquinone dyes, asdolapyridone dyes, thioindigo dyes, coumarin dyes, isoindolinone pigments, sichetopyrrolopyrrole pigments, condensed azo pigments, benzimidazolone pigments, dioxazine pigments, copper phthalocyanine pigments, and quinacridone pigments.

[0042] The colorant contained in the composition may be one kind or two or more kinds. The content of the colorant in the composition is, for example, 1.0 × 10 －８ It can be 0.5% by mass to 0.5% by mass.

[0043] When the composition contains additives, the total content thereof may be 15% by mass or less, 10% by mass or less, 5% by mass or less, or 1% by mass or less of the total composition. When the composition contains additives, the total content thereof may be 0.01% by mass or more, 0.05% by mass or more, or 0.1% by mass or more of the total composition.

[0044] The composition of the present disclosure may be used immediately after preparation, or may be stored before use. The storage conditions for storage are not particularly limited, but may be, for example, 0°C to 45°C. From the viewpoint of ensuring good quality, the storage temperature is preferably selected from the range of 0°C to 39°C, more preferably selected from the range of about 25°C ± 10°C, and even more preferably selected from the range of about 25 to 30°C.

[0045] The composition of the present disclosure has excellent storage stability. Specifically, the transmittance of the composition after storage is improved compared to when toluene is not added. Therefore, the composition of the present disclosure can maintain high transmittance even when stored for a long period of time. In the present disclosure, the storage stability of the composition was measured by measuring the transmittance of the composition stored under accelerated conditions. The transmittance measurement method used to evaluate storage stability will be described below.

[0046] In the examples described below, the storage stability of the composition was evaluated by (1) preparing a composition containing methyl methacrylate and toluene, (2) conducting a storage test including the following steps 1 to 7 in this order, and (3) measuring the transmittance of the composition stored under accelerated conditions.

[0047] Step 1: Inject 25 mL of the composition into the bottom of a pressure vessel (TVS-N2 type manufactured by Taiatsu Glass Industry Co., Ltd.). Step 2: Place a gasket between the top and bottom of the pressure vessel and seal the pressure vessel. Step 3: Feed nitrogen into the top tip of the pressure vessel and seal it at an internal pressure of 0.2 MPa, then check for one minute to see if the internal pressure changes. Step 4: Remove the internal pressure from the pressure vessel and attach a stopcock to the top tip of the pressure vessel. Step 5: Place the pressure vessel in an oil bath set to 80°C. Step 6: Store in the oil bath for 24 hours. Step 7: After 24 hours, remove the pressure vessel from the oil bath and place it in ice-cold water to rapidly cool it.

[0048] In the examples described below, the transmittance of a composition stored under accelerated conditions was measured by measuring the transmittance of the composition after storage. Specifically, the average transmittance (%) of the composition after storage was measured for light in the wavelength range of 300 nm to 370 nm when the optical path length was 10 mm. The average transmittance refers to the average value of the transmittance values ​​at each wavelength in 5-nm increments within the measured wavelength range of 300 nm to 370 nm. A spectrophotometer (Hitachi High-Tech Fielding Corporation's "Hitachi Spectrophotometer U-4000") was used for the measurement, but any commercially available spectrophotometer may also be used. A higher transmittance of a composition indicates improved transparency. Furthermore, a higher transmittance after storage indicates that the optical properties, such as transparency, of the composition are maintained. The average transmittance of a composition stored under accelerated conditions is preferably 98.10% or higher, and more preferably 98.50% or higher. Compositions containing methyl methacrylate are often used in molded articles that require transparency, and compositions exhibiting such transmittance are useful for molded articles that require transparency.

[0049] By mixing toluene and methyl methacrylate in a predetermined ratio, the composition of the present disclosure exhibits improved transmittance after storage compared to a composition that does not contain toluene, and exhibits high transmittance even after storage. This effect can be said to be an unexpected and surprising effect. Although the reason for this is unclear, it is thought that the addition of a small amount of toluene to methyl methacrylate causes some kind of effect (e.g., interaction between monomers) during storage.

[0050] <Polymer, Cured Product, and Molded Product> The polymer of the present disclosure is a polymer containing structural units derived from methyl methacrylate contained in the composition of the present disclosure described above. Here, the polymer is obtained by polymerizing components involved in polymerization contained in the composition and has structural units derived from the components involved in polymerization. The polymer of the present disclosure may contain structural units derived from methyl methacrylate contained in the composition of the present disclosure and structural units derived from other polymerization components. The weight-average molecular weight of the polymer of the present disclosure is not particularly limited and can be selected depending on the application of the polymer. The cured product of the present disclosure is a cured product of the composition of the present disclosure described above. Here, the cured product is a product obtained by curing the composition and may also contain components not involved in polymerization. However, depending on the method for curing the composition, it may be considered to be the same as the polymer described above (i.e., not containing components not involved in polymerization). The molded product of the present disclosure includes the polymer or cured product of the present disclosure described above. If the cured product can be considered to be the same as a polymer, the molded product will contain a polymer of the composition of the present disclosure. Preferably, the molded product contains a cured product obtained by curing only the composition of the present disclosure. The molded article may be an object obtained by molding a polymer or a cured product into any shape.

[0051] (Physical Properties of Polymer and Cured Product) The polymer and cured product of the present disclosure have excellent optical properties. Specifically, they tend to have excellent optical properties, such as transparency, compared to polymers or cured products obtained from compositions containing methyl methacrylate but not containing toluene. Polymers and cured products of methyl methacrylate compositions are often required to have high transparency for their applications. Therefore, the composition of the present application can provide a polymer or cured product with higher transparency than a polymer or cured product obtained from a composition not containing toluene. Furthermore, the composition of the present application exhibits higher transmittance than a composition not containing toluene even after long-term storage. Therefore, the composition of the present application can provide a polymer or cured product with high transparency even after long-term storage of the composition.

[0052] The transparency of a polymer or a cured product can be determined by measuring its transmittance. In the present disclosure, the transmittance may be measured on a produced polymer or cured product, or may be measured after the polymer or cured product has been subjected to an accelerated aging treatment. This method allows for efficient evaluation of the transparency of a polymer or cured product after long-term use.

[0053] The transmittance of a polymer or a cured product can be measured, for example, by the following method. First, a 50 mm x 50 mm x 3 mm test piece prepared from the polymer or the cured product is subjected to accelerated aging treatment by leaving it for 200 hours in an incubator ("Vacuum Oven VOS-301SD" manufactured by Tokyo Rikakikai Co., Ltd.) set at 80°C. Next, using the test piece after the accelerated aging treatment, the average transmittance (%) of light in the wavelength range of 380 nm to 780 nm when the optical path length is set to 50 mm is measured. The measurement is performed using a spectrophotometer ("Hitachi Spectrophotometer U-4000" manufactured by Hitachi High-Tech Fielding Corporation). From the viewpoint of optical properties, the average transmittance of the polymer or cured product after the accelerated aging treatment is preferably 81% or more, and more preferably 81.5% or more.

[0054] Whether the polymer and cured product of the present disclosure contain methyl methacrylate, toluene, or other components can be determined by known analytical methods, such as gas chromatography and liquid chromatography.

[0055] The polymer, cured product, and molded article of the present disclosure contain toluene in an amount of more than 0 ppm by mass and not more than 1000 ppm by mass, relative to the total mass of the polymer, cured product, or molded article. The concentration of toluene contained in the polymer, cured product, or molded article is preferably 5 ppm by mass or more, more preferably 50 ppm by mass or more, and even more preferably 100 ppm by mass or more, relative to the total mass. The upper limit of the toluene concentration contained in the polymer, cured product, or molded article is not particularly limited, and may be, for example, 800 ppm by mass or less, 700 ppm by mass or less, 600 ppm by mass or less, or 500 ppm by mass or less.

[0056] Furthermore, when the toluene concentration is in the range of less than 1000 ppm by mass, the transparency of a molded article obtained from the composition tends to be high. From the viewpoint of the transparency of the molded article, the concentration of toluene contained in the polymer, cured product, or molded article is preferably 800 ppm by mass or less, more preferably 700 ppm by mass or less, even more preferably 600 ppm by mass or less, particularly preferably 500 ppm by mass or less, and particularly preferably 400 ppm by mass or less, relative to the total mass of the polymer, cured product, or molded article.

[0057] <Method for producing polymethyl methacrylate> The method for producing polymethyl methacrylate of the present disclosure is a method for producing polymethyl methacrylate, including a step of polymerizing the methyl methacrylate contained in the composition of the present disclosure described above. Here, the polymethyl methacrylate of the present disclosure corresponds to a polymer obtained from the composition of the present disclosure, and also corresponds to a cured product obtained from the composition.

[0058] The method for polymerizing methyl methacrylate contained in the composition is not particularly limited, and may be carried out by a known method, such as bulk polymerization, cell cast polymerization, solution polymerization, suspension polymerization, or emulsion polymerization.

[0059] Specifically, the composition of the present disclosure can be used, for example, to form a methyl methacrylate polymer into a sheet (molded product) by bulk polymerization. Alternatively, in cell-cast polymerization, the composition can be cured into a cured product (molded product) by carrying out a polymerization reaction by subjecting the composition to heat treatment under predetermined heating conditions.

[0060] In the method for polymerizing methyl methacrylate contained in the composition of the present disclosure or the method for producing a molded article, the heating conditions, that is, the heating temperature and heating time, can be set taking into consideration, for example, the type and content of the selected polymerization regulator, polymerization initiator, and / or other components.

[0061] In cell cast polymerization, the heating temperature for producing a cured product and its molded article can be, for example, 50°C to 120°C. The heating time for production can be, for example, 1 hour to 20 hours. The heat treatment can be a heat treatment including multiple steps with different heating temperatures and / or heating times.

[0062] The cured product obtained by cell cast polymerization and its molded article can be produced, for example, by carrying out a heat treatment under heating conditions including the following steps 1 to 7.

[0063] Step 1: Raise the temperature from room temperature to 68°C over 20 minutes. Step 2: Hold at 68°C for 90 minutes. Step 3: Lower the temperature from 68°C to 64°C over 20 minutes. Step 4: Hold at 64°C for 90 minutes. Step 5: Raise the temperature from 64°C to 123°C over 10 minutes. Step 6: Hold at 123°C for 120 minutes. Step 7: Lower the temperature from 123°C to room temperature over 78 minutes.

[0064] In the method for producing a cured product and a molded article thereof, by carrying out the above steps 1 to 7 in this order, heat generation during the polymerization reaction can be suppressed and the polymerization can be completed stably.

[0065] When the composition of the present disclosure is subjected to a heat treatment, for example, a cell casting method (cell cast polymerization) using a cell capable of defining an enclosed space of a predetermined shape inside can be applied to form a molded article of a predetermined shape. The method for producing a molded article by the cell casting method will be specifically described below.

[0066] To produce a molded body by the cell casting method, a cell is first prepared. Here, an example of forming a plate-shaped molded body (sometimes called a cast plate) is described. Such a cell can be composed of at least two flat plate-shaped members and a sealing material (gasket) that is sandwiched between the two flat plate-shaped members and can seal the gap between the two opposing flat plate-shaped members as an airtight space.

[0067] The flat plate-like member may be in the form of a sheet or a belt. The flat plate-like member is made of a material that is not dissolved by the composition of the present disclosure, does not inhibit the polymerization reaction of the composition, and has sufficient heat resistance to the heating temperature in the heat treatment. Examples of suitable materials for the flat plate-like member include glass and metal.

[0068] Any suitable conventional sealing material can be used as the sealing material. The sealing material is composed of a material that is not dissolved by the composition of the present disclosure, does not inhibit the polymerization reaction of the composition, and has sufficient heat resistance to the heating temperature in the heat treatment. A specific example of a suitable sealing material is a gasket made of vinyl chloride resin.

[0069] Next, the composition of the present disclosure is injected into the gap (void) defined by the prepared cells by any suitable conventional method. The cells are then heat-treated under the heating conditions already described. The method of heat-treating the cells into which the composition of the present disclosure has been injected is not particularly limited. The heat-treating method for the cells may be the same as the conventionally known cell casting method, for example, by directly heating the cells from the outside using a hot air circulating oven, an infrared heater, or the like, or by providing any suitable conventionally known jacket on the outside of the cells and introducing a heat medium such as hot air, hot water, or steam into the jacket.

[0070] <Applications of Polymethyl Methacrylate and Molded Articles Thereof> The polymethyl methacrylate and molded articles thereof obtained from the composition of the present disclosure have excellent light transmittance, heat resistance, and weather resistance. Therefore, the composition of the present disclosure can be suitably applied to various applications that may be exposed to the external environment and further to heat sources and light sources, such as lighting fixtures, automobile parts, signs, and building materials.

[0071] Hereinafter, embodiments of the present disclosure will be described based on examples, but the present disclosure is not limited to the following examples.

[0072] Example 1 0.005% by mass of toluene (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added to and mixed with 99.999% by mass of methyl methacrylate to prepare composition 1. The resulting composition 1 was in the form of a solution.

[0073] Examples 2 and 3 and Comparative Examples 1 and 2 Compositions were prepared in the same manner as in Example 1, except that the toluene and its concentration (ppm by mass) added to methyl methacrylate were changed from Example 1 as shown in Table 1. All of the obtained compositions were in the form of solutions.

[0074] (1) Evaluation of Storage Stability of Compositions A storage test including the following steps 1 to 7 in this order was carried out on the compositions prepared in Examples 1 to 3 and Comparative Examples 1 and 2. The storage test was carried out under accelerated conditions (80°C) to evaluate the stability after long-term storage.

[0075] Step 1: Inject 25 mL of the composition into the bottom of a pressure vessel (TVS-N2 type manufactured by Taiatsu Glass Industry Co., Ltd.). Step 2: Place a gasket between the top and bottom of the pressure vessel and seal the pressure vessel. Step 3: Feed nitrogen into the top tip of the pressure vessel and seal it at an internal pressure of 0.2 MPa, then check for one minute to see if the internal pressure changes. Step 4: Remove the internal pressure from the pressure vessel and attach a stopcock to the top tip of the pressure vessel. Step 5: Place the pressure vessel in an oil bath set to 80°C. Step 6: Store in the oil bath for 24 hours. Step 7: After 24 hours, remove the pressure vessel from the oil bath and place it in ice-cold water to rapidly cool it.

[0076] The composition (3 mL) after the storage test was placed in a quartz glass cell (T-1, manufactured by Taiko Seisakusho Co., Ltd.) measuring 10 mm in length, 10 mm in width, and 45 mm in height. Using the composition placed in the quartz glass cell, the average transmittance (%) of light in the wavelength range of 300 nm to 370 nm was measured when the optical path length was 10 mm. The average transmittance is the average value of the transmittance values ​​at each wavelength in 5 nm increments from 300 nm to 370 nm. A spectrophotometer (Hitachi Spectrophotometer U-4000, manufactured by Hitachi High-Tech Fielding Corporation) was used for the measurement. The higher the average transmittance, the more it can be determined that optical properties such as high transparency are maintained even after storage. The results are shown in Table 1 and Figure 1.

[0077]

[0078] 1, the compositions of Examples 1 to 3, in which toluene was added to methyl methacrylate at a concentration of less than 1000 ppm by mass, had higher average transmittance after the storage test than Comparative Example 1, in which toluene was not added to methyl methacrylate, and Comparative Example 2, in which toluene was added to methyl methacrylate at a concentration of 1000 ppm by mass. These results suggest that adding toluene to methyl methacrylate at a concentration of less than 1000 ppm by mass contributes to improving the storage stability of the composition.

Claims

1. A composition comprising methyl methacrylate and toluene, wherein the concentration of the toluene is greater than 0 ppm by mass and less than 1,000 ppm by mass of the entire composition.

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

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

4. The composition according to claim 1, wherein the concentration of toluene is from 5 ppm by mass to 700 ppm by mass of the total composition.

5. The composition according to claim 1, wherein the concentration of toluene is from 100 ppm by mass to 600 ppm by mass of the total composition.

6. The composition of claim 1, wherein the methyl methacrylate comprises recycled methyl methacrylate or bio-derived methyl methacrylate.

7. The composition of claim 1 further comprising a (meth)acrylic acid ester other than methyl methacrylate.

8. The composition of claim 1, further comprising a polymer containing structural units derived from methyl methacrylate.

9. A polymer comprising structural units derived from methyl methacrylate contained in the composition according to any one of claims 1 to 8.

10. A molded article comprising the polymer according to claim 9.

11. A cured product of the composition according to any one of claims 1 to 8.

12. A molded article comprising the cured product according to claim 11.

13. A method for producing polymethyl methacrylate, comprising the step of polymerizing the methyl methacrylate contained in the composition according to any one of claims 1 to 8.

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