Composition, polymer, cured object, molded object, and method for producing poly(methyl methacrylate)

Abstract

To provide: a composition from which molded objects having excellent durability are obtained; a polymer, a cured object and a molded object which are obtained using the composition; and a method for producing poly(methyl methacrylate) using the composition.SOLUTION: The composition comprises methyl methacrylate and methyl pivalate and has a methyl pivalate concentration greater than 0 mass ppm and less than or equal to 10,000 mass ppm based on the entire composition.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[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 the various applications 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 the methyl(meth)acrylate, and the recovered methyl(meth)acrylate (sometimes referred to as recycled MMA or recycled MA) is used to produce new molded bodies; 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 uses for 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 matter in a reaction vessel in which raw material monomers and a polymerization initiator are reacted has been proposed (see Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-102190 Summary of the Invention [Problem to be solved by the invention]

[0006] In addition to improving the polymerization process of raw material monomers as described in Patent Document 1, another possible measure to improve the quality of polymethyl(meth)acrylate is to optimize the composition of raw material monomers. In view of the above circumstances, an object of one embodiment of the present disclosure is to provide a composition that can give a molded article having excellent durability, a polymer, a cured product, and a molded article that can be obtained using this composition, and a method for producing polymethyl methacrylate that uses this composition. [Means for solving the problem]

[0007] Means for solving the above problems include the following embodiments. <1> Contains methyl methacrylate and methyl pivalate, A composition having a concentration of methyl pivalate of more than 0 ppm by mass and not more than 10,000 ppm by mass in the entire composition. <2> The content of methyl methacrylate in the entire composition is 85% by mass or more. <1> The composition described in <3> The content of methyl methacrylate in the entire composition is 90% by mass or more. <1> or <2> The composition described in <4> The concentration of methyl pivalate is greater than 0 ppm by mass and less than 1000 ppm by mass in the entire composition. <1> ~ <3> The composition according to any one of the preceding claims. <5> The concentration of methyl pivalate is 50 ppm by mass to 600 ppm by mass of the total composition. <1> ~ <4> The composition according to any one of the preceding claims. <6> The methyl methacrylate comprises recycled methyl methacrylate or bio-derived methyl methacrylate; <1> ~ <5> The composition according to any one of the preceding claims. <7> Further containing (meth)acrylic acid esters other than methyl methacrylate, <1> ~ <6> The composition according to any one of the preceding claims. <8> Further comprising a polymer containing structural units derived from methyl methacrylate, <1> ~ <7> The composition according to any one of the preceding claims. <9> <1> ~ <8> A polymer comprising a structural unit derived from methyl methacrylate contained in the composition according to any one of claims 1 to 4. <10> <9> A molded article comprising the polymer described in 1. <11> <1> ~ <8> A cured product of the composition according to any one of claims 1 to 4. <12> <11> A molded article comprising the cured product according to claim 1. <13> <1> ~ <8> 10. A method for producing polymethyl methacrylate, comprising the step of polymerizing methyl methacrylate contained in the composition according to any one of claims 1 to 9. [Effects of the Invention]

[0008] According to one embodiment of the present disclosure, there are provided a composition that can give a molded article with excellent durability, a polymer, a cured product, and a molded article obtained using this composition, and a method for producing polymethyl methacrylate using this composition. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a graph showing the relationship between the concentration of methyl pivalate in the compositions prepared in the examples (with storage tests) and the 5% weight loss temperature of the cast plates. [Figure 2] 1 is a graph showing the relationship between the concentration of methyl pivalate in the compositions prepared in the examples (no storage test) and the 5% weight loss temperature of the cast plates. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present invention will be described, but 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 the present specification, the upper or lower limit of one numerical range may be replaced with the upper or lower limit of another numerical range. In addition, in the present specification, the upper or lower limit of a numerical range may be replaced with a value shown in the examples.

[0011] <Composition> The composition of the present disclosure contains methyl methacrylate and methyl pivalate, and the concentration of methyl pivalate is greater than 0 ppm by mass and not greater than 10,000 ppm by mass in the entire composition.

[0012] As will be shown in the examples described later, a composition containing methyl methacrylate and methyl pivalate tends to have a lower concentration of methyl methacrylate (residual MMA concentration) remaining in a molded article obtained from the composition, or a higher 5% weight loss temperature of the molded article, compared to a composition containing methyl methacrylate but not methyl pivalate. The lower the residual MMA concentration in the molded product, the fewer unpolymerized components there are in the molded product, and the more durable the molded product can be. The higher the 5% weight loss temperature of the molded body, the more resistant the molded body is to thermal decomposition, and the more excellent the durability (thermal stability) of the molded body is.

[0013] (methyl methacrylate) The compositions of the present disclosure include 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.

[0014] 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, etc. 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. When the content of methyl methacrylate in the composition is within the above range, it 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.

[0015] The methyl methacrylate contained in the composition may be synthesized by a known synthesis method, which is not particularly limited and may be the ACH method, the C4 direct oxidation method, or the alpha method.

[0016] The methyl methacrylate contained in the composition may include recycled methyl methacrylate. In this disclosure, recycled methyl methacrylate means methyl methacrylate obtained by depolymerization of polymethyl methacrylate (a reaction in which a polymer is decomposed to produce monomers). Depolymerization of polymethyl methacrylate can be effected, for example, by subjecting polymethyl methacrylate to heat treatment. The source of polymethyl methacrylate, which is the raw material for recycled methyl methacrylate, is not particularly limited as long as it is possible to recover methyl methacrylate. For example, the source of polymethyl methacrylate may be a molded article containing polymethyl methacrylate.

[0017] The methyl methacrylate included 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 preferably is a raw material derived from vegetable oil.

[0018] (Methyl pivalate) The compositions of the present disclosure include methyl pivalate. The concentration of methyl pivalate contained in the composition is not particularly limited, as long as it is more than 0 ppm by mass and 10,000 ppm by mass or less of the total composition. From the viewpoint of durability of the molded article, the concentration of methyl pivalate contained in the composition is preferably 10 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 total composition. The upper limit of the concentration of methyl pivalate contained in the composition is not particularly limited, and may be, for example, 8000 ppm by mass or less, 5000 ppm by mass or less, or 2000 ppm by mass or less. The addition of methyl pivalate to the composition can improve the durability of molded articles obtained from the composition. More specifically, the addition of methyl pivalate reduces the residual MMA concentration in the molded article or increases the 5% weight loss temperature of the molded article. Furthermore, this effect of adding methyl pivalate is observed whether the composition is stored or not.

[0019] As will be shown in the examples described later, when the concentration of methyl pivalate is in the range of less than 1000 ppm by mass, the 5% weight loss temperature of a molded article obtained from the composition tends to be high. Therefore, from the viewpoint of the durability of the molded article, the concentration of methyl pivalate contained in the composition 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, and particularly preferably 500 ppm by mass or less, of the total composition.

[0020] If necessary, the composition may contain a component other than methyl methacrylate and methyl pivalate. For example, the composition may contain 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.

[0021] ((Meth)acrylic acid ester) The composition may contain, in addition to methyl methacrylate, a (meth)acrylic acid ester other than methyl methacrylate (hereinafter also simply referred to as a (meth)acrylic acid ester). Specific examples of (meth)acrylic acid esters include methyl acrylate, (meth)acrylic acid esters, Examples of the acrylate include 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 it may be either 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.

[0022] 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, of the entire composition. When the composition contains a (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 of the total composition.

[0023] 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 other (meth)acrylic acid esters polymerizable with methyl methacrylate include the same as those described above.

[0024] (low content ingredients) The composition may contain minor components other than methyl pivalate, which may be present in the composition as by-products produced during the production of methyl methacrylate or during the recycling process of polymethyl methacrylate. In the present disclosure, a low content component means a component that is contained in the composition at a concentration of 10,000 ppm by mass or less.

[0025] Examples of components other than methyl pivalate that may be contained in the composition at low content include carboxylic acid esters other than methyl pivalate, aromatic hydrocarbon compounds, aliphatic hydrocarbon compounds, alcohols, and butyl acrylate. The composition may contain only one or two or more low content components other than methyl pivalate.

[0026] 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 toluene and styrene. Specific examples of the aliphatic hydrocarbon compound include 1-octene and 1-octadecene.

[0027] When the composition contains low-content components other than methyl pivalate, the concentration of each low-content component is preferably 8000 ppm by mass or less, more preferably 6000 ppm by mass or less, and even more preferably 5000 ppm by mass or less, of the total composition. When the composition includes low-content components other than methyl pivalate, the concentration of each low-content component may be 1 ppm by weight or more, 2 ppm by weight or more, or 5 ppm by weight or more of the total composition.

[0028] (additives) If necessary, the composition may contain additives, such as a mold release agent, a polymerization regulator, a polymerization initiator, an ultraviolet absorber, and a colorant. The composition may contain one or more additives.

[0029] Examples of release agents that the composition may contain 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 mold release agents include sodium di-(2-ethylhexyl) sulfosuccinate, stearyl alcohol, methyl stearate, and stearic acid amide.

[0030] The composition may contain one or more types of release agents. The content of the release agent in the composition can be, for example, 0.01% by mass to 1.0% by mass of the entire composition.

[0031] The polymerization regulator (an additive that regulates the polymerization rate in a polymerization reaction) that may be contained in the composition may be any suitable polymerization regulator known in the art. Examples of such polymerization regulators include compounds that can regulate the polymerization rate in a direction that decreases the polymerization rate. Specific examples of the polymerization regulator 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.

[0032] The composition may contain one or more types of polymerization regulators. The content of the polymerization regulator in the composition can be, for example, 0.001% by mass to 0.5% by mass of the total composition.

[0033] 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.

[0034] 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).

[0035] 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.

[0036] 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-tert-butylperoxy-2-ethylhexanoate, and 1,1,3,3-tert-butylperoxy-2-ethylhexanoate. tetramethylbutylperoxy-2-ethylhexanoate, and tert-amylperoxy-2-ethylhexanoate.

[0037] Specific examples of percarbonate initiators include tert-butylperoxyallyl carbonate and tert-butylperoxyisopropyl carbonate.

[0038] 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.

[0039] The composition may contain one or more types of polymerization initiators. The content of the polymerization initiator in the composition can be, for example, 0.01% by mass to 5% by mass of the entire composition.

[0040] 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.

[0041] 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.

[0042] The composition may contain one or more types of ultraviolet absorbers. The content of the ultraviolet absorber in the composition can be, for example, 0.001% by mass to 1% by mass of the entire composition.

[0043] 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.

[0044] The composition may contain one or more types of colorants. The content of the colorant in the composition is, for example, 1.0 × 10 -8 The content can be 0.5% by mass to 0.5% by mass.

[0045] 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.

[0046] 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°C to 30°C.

[0047] <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 contain components that are not involved in polymerization. However, depending on the method for curing the composition, it may be considered to be the same as the above-mentioned polymer (i.e., not containing components that are not involved in polymerization). The molded article of the present disclosure includes the polymer or cured product of the present disclosure described above. If the cured product can be considered the same as the polymer, the molded article will include a polymer of the composition of the present disclosure. The molded article is preferably a molded article containing a cured product obtained by curing only the composition of the present disclosure. The molded article may also be an object obtained by molding the polymer or cured product into any shape.

[0048] Whether the polymer, cured product, and molded article of the present disclosure contain methyl methacrylate, methyl pivalate, or other components can be determined by known analytical methods, such as gas chromatography and liquid chromatography.

[0049] The residual MMA concentration in the polymer, cured product, and molded product of the present disclosure may be, for example, less than 8,300 ppm by mass, 8,100 ppm by mass or less, 8,000 ppm by mass or less, 7,800 ppm by mass or less, or 7,600 ppm by mass or less. In the present disclosure, the residual MMA concentration in the polymer, cured product, or molded product is measured by the method described in the Examples.

[0050] The 5% weight loss temperature of the polymer, cured product, and molded product of the present disclosure may be, for example, 280° C. or higher. In the present disclosure, the 5% weight loss temperature of the polymer, cured product, or molded product is measured by the method described in the Examples.

[0051] The polymer, cured product, and molded article of the present disclosure contain methyl pivalate, and the concentration of methyl pivalate is greater than 0 ppm by mass and not more than 10,000 ppm by mass relative to the total mass of the polymer, cured product, or molded article. The concentration of methyl pivalate contained in the polymer, cured product, or molded article is preferably 10 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 of the polymer, cured product, or molded article. The upper limit of the concentration of methyl pivalate contained in the polymer, cured product, or molding is not particularly limited, and may be, for example, 8000 ppm by mass or less, 5000 ppm by mass or less, or 2000 ppm by mass or less.

[0052] Furthermore, when the concentration of methyl pivalate contained in the polymer, cured product, or molded article is less than 1000 ppm by mass, the polymer, cured product, or molded article tends to have a high 5% weight loss temperature. The higher the 5% weight loss temperature of the polymer, cured product, or molded article, the less susceptible to thermal decomposition and the more excellent the thermal stability. From the viewpoint of thermal stability, the concentration of methyl pivalate 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, and particularly preferably 500 ppm by mass or less, relative to the total mass of the polymer, cured product, or molded article.

[0053] <Method for producing polymethyl methacrylate> The method for producing polymethyl methacrylate of the present disclosure includes a step of polymerizing the methyl methacrylate contained in the composition of the present disclosure. Here, the polymethyl methacrylate of the present disclosure includes a polymer obtained from the composition of the present disclosure and a cured product obtained from the composition.

[0054] 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.

[0055] 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. Furthermore, in cell-cast polymerization, the composition is heated under predetermined heating conditions to allow the polymerization reaction to proceed, thereby forming a cured product (molded product) from the composition.

[0056] 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, such as 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.

[0057] In cell cast polymerization, when producing a cured product and its molded article, the heating temperature can be, for example, 50°C to 120°C. The heating time 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.

[0058] A cured product obtained by cell cast polymerization and a molded product thereof can be produced, for example, by carrying out a heat treatment under heating conditions including the following steps 1 to 7.

[0059] 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: Reduce the temperature from 68°C to 64°C over 20 minutes. Step 4: Hold at 64°C for 90 minutes. Step 5: Increase the temperature from 64°C to 123°C over 10 minutes. Step 6: Hold at 123°C for 120 minutes. Step 7: Cool from 123°C to room temperature over 78 minutes.

[0060] 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.

[0061] 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.

[0062] In manufacturing a green body by the cell casting method, a cell is first prepared. Here, an example of forming a green body in the form of a plate (sometimes called a cast plate) will be described. Such a cell can be composed of at least two flat plate-like members and a sealing material (gasket) that is sandwiched between the two flat plate-like members and can seal the gap between the two opposing flat plate-like members as an airtight space.

[0063] 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.

[0064] 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.

[0065] 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, as in the conventionally known cell casting method, a method in which the cells are directly heat-treated from the outside using a hot air circulating oven, an infrared heater, or the like, or a method in which a conventionally known jacket is further provided on the outside of the cells and a heat medium such as hot air, hot water, or steam is introduced into the jacket.

[0066] <Uses of polymethyl methacrylate and its molded products> Polymethyl methacrylate and molded articles thereof obtained from the composition of the present disclosure have excellent light transmittance, heat resistance, and weather resistance, and are therefore suitable for a variety of applications that may be exposed to the external environment and even heat and light sources, such as lighting fixtures, automobile parts, signs, and building materials. [Example]

[0067] Hereinafter, embodiments of the present disclosure will be described based on examples, but the present disclosure is not limited to the following examples.

[0068] Example 1 (Preparation of Composition) Composition 1 was prepared by adding 0.01% by mass of methyl pivalate (manufactured by Tokyo Chemical Industry Co., Ltd.) to 99.99% by mass of methyl methacrylate and mixing them. The obtained composition 1 was in a liquid state. The composition of composition 1 is also shown in Table 1.

[0069] Composition 1 was subjected to a storage test including the following steps 1 to 7 in this order to obtain composition 1' after the storage test. The storage test was carried out under accelerated conditions (60°C) in order to evaluate the durability of a molded article obtained using the composition after long-term storage.

[0070] Step 1: 25 mL of the composition is poured 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 to seal it. Step 3: Nitrogen is fed into the top tip of the pressure vessel, and the vessel is sealed with an internal pressure of 0.2 MPa. Check that the internal pressure does not change for one minute. Step 4: Release the internal pressure from the pressure vessel and attach a stopcock to the top of the pressure vessel. Step 5: Place the pressure vessel in an oil bath set at 60°C. Step 6: Store in an 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 down.

[0071] Composition 1' (99.84 parts by mass), sodium di-(2-ethylhexyl) sulfosuccinate (0.05 parts by mass) as a mold release agent, terpinolene (0.03 parts by mass) as a polymerization regulator, and 2,2'-azobisisobutyronitrile (0.08 parts by mass) as a polymerization initiator were mixed to obtain Composition 1'' for forming a molded body (cast plate). The obtained Composition 1'' was in a liquid state.

[0072] (Cast plate production) A cell was prepared in which a 3.8 mm thick vinyl chloride resin gasket was sandwiched between two opposing glass plates, thereby defining a sealed gap between the vinyl chloride resin gasket and the two glass plates. Composition 1″ was poured into the gap within this cell. The cell into which Composition 1″ had been poured was placed in an oven, and a heat treatment was carried out under heating conditions including the following steps 1 to 7 in this order, thereby polymerizing Composition 1″ and producing a cast plate, which was a 3 mm thick, 100 mm square molded body.

[0073] 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: Reduce the temperature from 68°C to 64°C over 20 minutes. Step 4: Hold at 64°C for 90 minutes. Step 5: Increase the temperature from 64°C to 123°C over 10 minutes. Step 6: Hold at 123°C for 120 minutes. Step 7: Cool from 123°C to room temperature over 90 minutes.

[0074] (Measurement of residual MMA concentration) 0.5 g of the cast plate prepared as described above was cut and precisely weighed, and 10 cc of acetone (special grade) was added and dissolved. 1 cc of an internal standard solution (a solution of 1% methyl isobutyl ketone (MIBK) dissolved in methanol) was added to the resulting acetone solution and stirred. 30 cc of methanol was added to the resulting mixture to reprecipitate the methyl methacrylate polymer. The supernatant solution was then collected as a sample solution. The amount of residual methyl methacrylate in the sample solution was measured using the following gas chromatography apparatus.

[0075] (Measurement conditions) Equipment: GC-2010 Plus (manufactured by Shimadzu Corporation) Column: DB-1 (Agilent Technologies) Detector: FID 2010 Plus (Shimadzu Corporation) Column oven conditions Initial temperature: 40°C (hold time 1 minute) Heating rate: 8°C / min Intermediate temperature: 120℃ (hold time 0 minutes) Heating rate: 20°C / min Final temperature: 250℃ (hold time 5 minutes) Sample vaporization conditions Vaporization chamber temperature: 300℃ Carrier gas: Helium Pressure: 50kPa Total flow: 58.3mL / min Column flow rate: 1.08 mL / min Linear speed: 31.1cm / sec Purge dose: 3.0mL / min Split ratio: 50 Detector conditions Detector temperature: 300℃ Sampling rate: 40msec Make-up gas: N2 Make-up flow rate: 30 mL / min H2 flow rate: 40mL / min Air flow rate: 400mL / min Autosampler conditions Injection volume: 1μL

[0076] The peak area (a1) corresponding to methyl methacrylate and the peak area (b1) corresponding to methyl isobutyl ketone detected when the sample solution was measured under the above measurement conditions were measured. From these peak areas, the peak area ratio A (=a1 / b1) was calculated.

[0077] A standard sample with a mass ratio of methyl methacrylate content to methyl isobutyl ketone content of W0 (known) was measured under the above measurement conditions, and the peak area (a0) corresponding to the detected methyl methacrylate and the peak area (b0) corresponding to methyl isobutyl ketone were measured. The peak area ratio A0 (= a0 / b0) was then calculated from these peak areas. Next, the factor f (= W0 / A0) was calculated from the peak area ratio A0 and the above mass ratio W0.

[0078] Next, the mass ratio W of methyl methacrylate to methyl isobutyl ketone contained in sample solution 1 was calculated by multiplying the peak area ratio A by the factor f. The residual MMA concentration (ppm by mass) of the cast plate was calculated from the calculated mass ratio W and the mass of the cast plate used to prepare the sample solution. The results are shown in Table 1.

[0079] (Measurement of 5% weight loss temperature) The cast plate prepared as described above was crushed to a diameter or side length of 0.5 mm or less, and 9.3 mg of the crushed material was placed on an aluminum pan (Hitachi High-Tech Science Corporation, P / N SSC000E030 Open Sample Pan, diameter 5 mm). The weight change of the crushed material was measured using a thermogravimetric / differential thermal analyzer (Hitachi High-Tech Science Corporation, TG / DTA7200) at a nitrogen gas flow rate of 200 mL / min and a heating rate of 10 °C / min from 45 °C to 520 °C. The crushed material's weight decreased with increasing temperature. The temperature at which the crushed material's weight had decreased by 95 wt% (5% weight loss temperature, °C) was calculated, with the weight of the crushed material at the initial temperature (45 °C) defined as 100 wt%. The results are shown in Table 1.

[0080] <Examples 2 to 4 and Comparative Example 1> Cast plates of Examples 2 to 4 and Comparative Example 1 were produced in the same manner as in Example 1, except that compositions in which the amount of methyl pivalate added was changed to the values ​​shown in Table 1 were used. The residual MMA concentration and 5% weight loss temperature of the cast plate were measured in the same manner as in Example 1. The results are shown in Table 1.

[0081] [Table 1]

[0082] <Examples 5 to 7 and Comparative Example 2> Cast plates of Examples 5 to 7 and Comparative Example 2 were produced in the same manner as in Example 1, except that compositions in which the amount of methyl pivalate added was changed to the values ​​shown in Table 1 were used and that the prepared compositions were not subjected to a storage test. The residual MMA concentration and 5% weight loss temperature of the cast plate were measured in the same manner as in Example 1. The results are shown in Table 2.

[0083] [Table 2]

[0084] As shown in Tables 1 and 2, the cast plates of the examples produced using a composition in which methyl pivalate was added to methyl methacrylate satisfied at least one of the following conditions A and B and exhibited excellent durability. Condition A: The residual MMA concentration of the molded body is lower than that of the molded body of the comparative example in which methyl pivalate is not added to methyl methacrylate. Condition B: The 5% weight loss temperature of the molded body is higher than that of the molded body of the comparative example in which methyl pivalate is not added to methyl methacrylate Furthermore, as shown in Tables 1 and 2, the effect of adding methyl pivalate on improving the durability of the molded article was observed both in the case where the composition was stored after preparation and in the case where it was not stored.

Claims

1. Contains methyl methacrylate and methyl pivalate, A composition having a concentration of methyl pivalate of more than 0 ppm by mass and not more than 10,000 ppm by mass of the total 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. 2. The composition of claim 1, wherein the concentration of methyl pivalate is greater than 0 ppm by weight and less than 1000 ppm by weight of the total composition.

5. 2. The composition according to claim 1, wherein the concentration of methyl pivalate is from 50 ppm by mass to 600 ppm by mass of the total composition.

6. 10. The composition of claim 1, wherein the methyl methacrylate comprises recycled methyl methacrylate or bio-sourced 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 a structural unit 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 a step of polymerizing methyl methacrylate contained in the composition according to any one of claims 1 to 8.

Images