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

Abstract

The present invention addresses the problem of providing: a composition from which molded objects having excellent heat resistance are obtained; a polymer, a cured object, and a molded object which are obtained using this composition; and a method for producing poly(methyl methacrylate) using this composition.　This composition comprises methyl methacrylate, methyl pivalate, and water and has a methyl pivalate concentration higher than 0 mass ppm but not higher than 10,000 mass ppm with respect to the whole composition and a water concentration higher than 0 mass ppm but not higher than 10,000 mass ppm with respect to the whole 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 the improvement of the polymerization process of raw material monomers as described in Patent Document 1, there is a need for a method for improving the quality of polymethyl(meth)acrylate by optimizing 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 heat resistance, 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, methyl pivalate, and water, wherein 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, and the concentration of water is greater than 0 ppm by mass and not greater than 10,000 ppm by mass in the entire composition. <2> The composition according to <1>, wherein the content of methyl methacrylate is 85% by mass or more in the entire composition. <3> The composition according to <1> or <2>, wherein the content of methyl methacrylate is 90% by mass or more in the entire composition. <4> The composition according to any one of <1> to <3>, wherein the methyl methacrylate includes recycled methyl methacrylate or bio-derived methyl methacrylate. <5> The composition according to any one of <1> to <4>, further comprising a (meth)acrylic acid ester other than methyl methacrylate. <6> The composition according to any one of <1> to <5>, further comprising a polymer including a structural unit derived from methyl methacrylate. <7> A polymer comprising a structural unit derived from methyl methacrylate contained in the composition according to any one of <1> to <6>. <8> A molded article comprising the polymer according to <7>. <9> A cured product of the composition according to any one of <1> to <6>. <10> A molded article comprising the cured product according to <9>. <11> A method for producing polymethyl methacrylate, comprising a step of polymerizing methyl methacrylate contained in the composition according to any one of <1> to <6>.

[0008] According to one embodiment of the present disclosure, there are provided a composition that can give a molded article having excellent heat resistance, 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.

[0009] 1 is a graph showing the relationship between the water concentration of the compositions prepared in the examples and the 5% weight loss temperature of the cast plates.

[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 is a composition containing methyl methacrylate, methyl pivalate, and water, wherein the concentration of methyl pivalate is more than 0 ppm by mass and not more than 10,000 ppm by mass of the total composition, and the concentration of water is more than 0 ppm by mass and not more than 10,000 ppm by mass of the total composition.

[0012] As shown in the examples described below, molded articles obtained using a composition in which methyl pivalate and water are added to a composition containing methyl methacrylate exhibit superior heat resistance compared to molded articles obtained using a composition in which only methyl pivalate is added to a composition containing methyl methacrylate. Specific indicators of the heat resistance of molded articles include the 5% weight loss temperature and glass transition temperature. The higher the 5% weight loss temperature of the molded article, the less likely the molded article is to thermally decompose, and the molded article can be judged to have excellent durability (thermal stability). The higher the glass transition temperature of the molded article, the more likely the molded article is to have excellent heat resistance. Molded articles obtained using the composition of the present disclosure have at least an improved 5% weight loss temperature or glass transition temperature, or both.

[0013] (Methyl methacrylate) The composition of the present disclosure contains methyl methacrylate. In the present 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 the present disclosure is not limited thereto, 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. 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.

[0015] 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.

[0016] 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.

[0017] 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.

[0018] (Methyl pivalate) The composition of the present disclosure contains 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.

[0019] As shown in the Reference Examples described later, a composition containing methyl methacrylate to which methyl pivalate has been added tends to produce a molded article with a lower residual MMA concentration than a composition containing methyl methacrylate but not methyl pivalate. A low residual MMA concentration in a molded article means that the molded article contains fewer unpolymerized components and has superior durability or heat resistance.

[0020] 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.

[0021] The upper limit of the concentration of methyl pivalate contained in the composition may be, for example, 5000 ppm by mass or less, 2000 ppm by mass or less, 1000 ppm by mass or less, or 600 ppm by mass or less.

[0022] (Water) The composition of the present disclosure contains water. The concentration of water 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.

[0023] From the viewpoint of improving the heat resistance of the molded body, the concentration of water contained in the composition is preferably 10 ppm by mass or more, more preferably 50 ppm by mass or more, even more preferably 100 ppm by mass or more, even more preferably 500 ppm by mass or more, and even more preferably 1000 ppm by mass or more, based on the total composition.

[0024] The upper limit of the concentration of water contained in the composition may be, for example, less than 10,000 ppm by mass, 9,000 ppm by mass or less, 8,000 ppm by mass or less, or 7,000 ppm by mass or less.

[0025] If necessary, the composition may contain a component other than methyl methacrylate, methyl pivalate, and water. 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.

[0026] ((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 (meth)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.

[0027] 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 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, based on the total composition.

[0028] 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.

[0029] (Low Content Component) The composition may contain a low content component other than methyl pivalate or water. 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 10,000 ppm by mass or less.

[0030] Examples of low content components other than methyl pivalate or water that may be contained in the composition include carboxylic acid esters other than methyl pivalate, aromatic hydrocarbon compounds, aliphatic hydrocarbon compounds, alcohols, butyl acrylate, etc. The low content components other than methyl pivalate or water contained in the composition may be one type only or two or more types.

[0031] 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 aliphatic hydrocarbon compounds include 1-octene and 1-octadecene.

[0032] When the composition contains low-content components other than methyl pivalate or water, 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, based on the total composition. When the composition contains low-content components other than methyl pivalate or water, the concentration of each low-content component 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.

[0033] (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.

[0034] 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.

[0035] 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.

[0036] 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 slows it down. 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.

[0037] 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.

[0038] 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.

[0039] 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).

[0040] 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.

[0041] 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.

[0042] Specific examples of percarbonate initiators include tert-butylperoxyallyl carbonate and tert-butylperoxyisopropyl carbonate.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] <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 a polymer 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 cured composition and may also contain components not involved in polymerization. However, depending on the method for curing the composition, it may be considered the same as the above-mentioned polymer (i.e., does not contain 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 the same as a polymer, the molded product will contain a polymer of the composition of the present disclosure. Preferably, the molded product is a molded product containing 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.

[0053] The polymer, cured product, and molded article of the present disclosure contain methyl pivalate. 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. From the viewpoint of the durability of the molded article, the concentration of methyl pivalate 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 of the present disclosure. The upper limit of the concentration of methyl pivalate may be, for example, 5,000 ppm by mass or less, 2,000 ppm by mass or less, 1,000 ppm by mass or less, or 600 ppm by mass or less, relative to the total mass of the polymer, cured product, or molded article of the present disclosure.

[0054] The polymer, cured product, or molded article of the present disclosure contains water. The concentration of water 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. From the viewpoint of improving the heat resistance of the polymer, cured product, or molded article, the concentration of water is preferably 10 ppm by mass or more, more preferably 50 ppm by mass or more, even more preferably 100 ppm by mass or more, even more preferably 500 ppm by mass or more, and even more preferably 1,000 ppm by mass or more, relative to the total mass of the polymer, cured product, or molded article.

[0055] The upper limit of the water concentration contained in the polymer, cured product, or molded product may be, for example, less than 10,000 ppm by mass, 9,000 ppm by mass or less, 8,000 ppm by mass or less, or 7,000 ppm by mass or less, relative to the total mass of the polymer, cured product, or molded product.

[0056] From the viewpoint of the heat resistance of the molded body, it is preferable that the concentration of methyl pivalate is more than 0 ppm by mass and not more than 10,000 ppm by mass, and the concentration of water is more 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 body. The combination of the preferred ranges of the methyl pivalate concentration and the water concentration may be any combination of appropriate ranges within the respective concentration ranges described above. From the viewpoint of improving the 5% weight loss temperature and glass transition temperature of the molded body, it is preferable that the concentration of methyl pivalate is more than 0 ppm by mass and not more than 9,000 ppm by mass, and the concentration of water is more than 0 ppm by mass and not more than 9,000 ppm by mass. The combination of the preferred ranges of the methyl pivalate concentration and the water concentration may be any combination of appropriate ranges within the respective concentration ranges described above.

[0057] Whether the polymer and cured product of the present disclosure contain methyl methacrylate, methyl pivalate, water, or other components can be determined by known analytical methods. Examples of known analytical methods include gas chromatography and liquid chromatography. Note that whether the composition of the present disclosure contains methyl methacrylate, methyl pivalate, methyl methylbutenoate, or other components can also be determined by known analytical methods similar to those described above. Examples of known analytical methods include gas chromatography and liquid chromatography.

[0058] From the viewpoint of the heat resistance of the molded body, the 5% weight loss temperature of the polymer, cured product, and molded body is preferably 278°C or higher, more preferably 280°C or higher, and even more preferably 282°C or higher. In the present disclosure, the 5% weight loss temperature of the polymer, cured product, or molded body is measured by the method described in the Examples. Note that the following is an example of a measurement method, and the 5% weight loss temperature may be measured by a similar method that can measure the 5% weight loss temperature (for example, a method in which appropriate conditions such as the mass or shape of the pulverized material, the heating temperature or heating rate are appropriately changed so that the 5% weight loss temperature can be measured) or by other known methods.

[0059] (Measurement of 5% weight loss temperature) The polymer, cured product, or molded product to be measured is crushed to a diameter or side length of 0.5 mm or less, and the crushed product obtained is placed on a commercially available aluminum pan. Using a commercially available thermogravimetric / differential thermal analyzer, the nitrogen gas flow rate is 200 mL / min, and the temperature is increased from 45 ° C to 520 ° C at a heating rate of 10 ° C / min, and the weight change of the crushed product is measured. Since the weight of the crushed product decreases as the temperature increases, the weight of the crushed product at the temperature at the start of the measurement (45 ° C) is taken as 100 wt%, and the temperature at which the weight of the crushed product has decreased to 95 wt% (5% weight loss temperature, ° C) is determined. In the examples, the aluminum pan used is a "P / N SSC000E030 Open Sample Pan" (diameter 5 mm) manufactured by Hitachi High-Tech Science Corporation. However, other aluminum pans or pans made of different metals that can be used may also be used. In the examples, the thermogravimetric / differential thermal analyzer used is a "TG / DTA7200" manufactured by Hitachi High-Tech Science Corporation, but other commercially available products may also be used for the measurements.

[0060] From the viewpoint of the heat resistance of the molded article, the glass transition temperature of the polymer, cured product, or molded article is preferably 108°C or higher, more preferably 109°C or higher, and even more preferably 110°C or higher. In the present disclosure, the glass transition temperature of the polymer, cured product, or molded article is measured by the method described in the Examples. Note that the following is an example of a measurement method similar to that in the Examples, and measurement may be performed by a similar method (for example, a method in which appropriate conditions such as the shape of the object to be measured, the temperature or rate of heating are appropriately changed so that the glass transition temperature can be measured) or by another known method.

[0061] The glass transition temperature (°C) can be measured in accordance with JIS-K7121 using a sample obtained by pulverizing a polymer, cured product, or molded article to be measured to a diameter or side length of 0.5 mm or less. The glass transition temperature can be measured using a commercially available differential scanning calorimeter with a nitrogen gas flow rate of 50 mL / min. Specifically, the sample is heated from room temperature (approximately 23°C) to 150°C at a rate of 20°C / min (primary heating) and held at 150°C for 5 minutes to completely melt. The sample is then cooled from 150°C to -35°C at a rate of 10°C / min and held at -35°C for 1 minute. The sample is then heated again to 210°C at a rate of 10°C / min (secondary heating). The glass transition temperature (°C) is determined by the intersection of the step-change partial curve during the secondary heating with a straight line equidistant from the two baseline extensions along the vertical axis (midpoint glass transition temperature). In the examples, a differential scanning calorimeter "DSC7020" manufactured by Hitachi High-Tech Science Corporation is used.

[0062] From the viewpoint of durability of the molded article, the residual MMA concentration of the polymer, cured product, and molded article may be, for example, 9,000 ppm by mass or less. In the present disclosure, the residual MMA concentration of the polymer, cured product, or molded article is measured by the method described in the Examples. Note that the following is an example of the measurement method, and the residual MMA concentration may be measured by a similar method that can measure the residual MMA concentration (for example, a method in which the cutting amount, dissolution temperature, type of solvent, or measurement conditions are appropriately changed so that the residual MMA concentration can be measured) or by other known methods.

[0063] (Measurement of Residual MMA Concentration) 0.5 g is cut and precisely weighed from the polymer, cured product, or molded article to be measured, and 10 cc of acetone (special grade) is added and dissolved. 1 cc of an internal standard solution (a solution of 1% methyl isobutyl ketone (MIBK) dissolved in methanol) is added to the resulting acetone solution and stirred. Methanol is added to the resulting mixture to reprecipitate the methyl methacrylate polymer. The supernatant solution is then collected as a sample solution. The amount of residual methyl methacrylate contained in the sample solution is measured using the following gas chromatography apparatus.

[0064] (Measurement conditions) Apparatus: GC-2010 Plus (Shimadzu Corporation) Column: DB-1 (Agilent Technologies, Inc.) Detector: FID 2010 Plus (Shimadzu Corporation) Column oven conditions Initial temperature: 40°C (hold time 1 min) Heating rate: 8°C / min Intermediate temperature: 120°C (hold time 0 min) Heating rate: 20°C / min Final temperature: 250°C (hold time 5 min) Sample vaporization conditions Vaporization chamber temperature: 300°C Carrier gas: Helium Pressure: 50 kPa Total flow rate: 58.3 mL / min Column flow rate: 1.08 mL / min Linear velocity: 31.1 cm / sec Purge dose: 3.0 mL / min Split ratio: 50 Detector conditions Detector temperature: 300°C Sampling rate: 40 msec Make-up gas: N ２ Make-up flow rate: 30 mL / min H2 flow rate: 40 mL / min Air flow rate: 400 mL / min Autosampler conditions Injection volume: 1 μL

[0065] The peak area (a1) corresponding to methyl methacrylate and the peak area (b1) corresponding to methyl isobutyl ketone detected when the sample solution is measured under the above measurement conditions are measured. From these peak areas, the peak area ratio A (= a1 / b1) is calculated.

[0066] A standard sample having a mass ratio of methyl methacrylate content to methyl isobutyl ketone content of W0 (known) is measured under the above measurement conditions, and the detected peak area (a0) corresponding to methyl methacrylate and the peak area (b0) corresponding to methyl isobutyl ketone are measured. The peak area ratio A0 (= a0 / b0) is then calculated from these peak areas. The factor f (= W0 / A0) is then calculated from the peak area ratio A0 and the mass ratio W0.

[0067] Next, the mass ratio W of methyl methacrylate to methyl isobutyl ketone contained in sample solution 1 is calculated by multiplying the peak area ratio A by the factor f. The residual MMA concentration (ppm by mass) of the cast plate is calculated from the calculated mass ratio W and the mass of the cast plate used to prepare the sample solution.

[0068] <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.

[0069] 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.

[0070] Specifically, the composition of the present disclosure can be used, for example, by bulk polymerization to form a methyl methacrylate polymer into a sheet (molded product). Furthermore, in cell-cast polymerization, the composition is heated under predetermined heating conditions to promote the polymerization reaction, thereby forming a cured product (molded product) from the composition.

[0071] 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.

[0072] 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.

[0073] 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.

[0074] 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.

[0075] 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.

[0076] 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.

[0077] 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.

[0078] 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.

[0079] 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.

[0080] 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 outside the cells and a heat medium such as hot air, hot water, or steam is introduced into the jacket.

[0081] <Applications of Polymethyl Methacrylate and Molded Articles Thereof> 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 further to heat and light sources, such as lighting fixtures, automobile parts, signs, and building materials.

[0082] Hereinafter, embodiments of the present disclosure will be described based on examples, but the present disclosure is not limited to the following examples.

[0083] Example 1 Preparation of Composition 99.87% by mass of methyl methacrylate was mixed with 0.03% by mass of methyl pivalate (manufactured by Tokyo Chemical Industry Co., Ltd.) and 0.1% by mass (1000 ppm by mass) of water to prepare Composition 1. The resulting Composition 1 was liquid. The composition of Composition 1 is also shown in Table 1.

[0084] 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) to evaluate the stability after long-term storage.

[0085] 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 60°C. Step 6: Store in the oil bath for 24 or 18 hours. Step 7: Remove the pressure vessel from the oil bath and place it in ice-cold water to rapidly cool it.

[0086] 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 article (cast plate). The obtained Composition 1" was in a liquid state.

[0087] (Preparation of Cast Plate) A cell was prepared in which a 3.8 mm thick vinyl chloride resin gasket was sandwiched between two opposing glass plates, and a gap could be defined by 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 a cast plate was prepared as a molded product of a methyl methacrylate polymer, measuring 3 mm thick and 100 mm square.

[0088] 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 90 minutes.

[0089] <Examples 2 to 4, 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 water added was changed to the values ​​shown in Table 1 were used.

[0090] (Measurement of 5% Weight Loss Temperature) The 5% weight loss temperatures of the cast plates produced in Examples 1 to 4 and Comparative Example 1 were measured by the following method. The results are shown in Table 1 and FIG.

[0091] The cast plate was crushed to a diameter or length of each side of 0.5 mm or less, and 9.3 mg of the resulting crushed material was placed on an aluminum pan (Hitachi High-Tech Science Corporation, "P / N SSC000E030 Open Sample Pan," diameter 5 mm). Using a thermogravimetric / differential thermal analyzer (Hitachi High-Tech Science Corporation, "TG / DTA7200"), the weight change of the crushed material was measured while heating from 45 ° C. to 520 ° C. at a nitrogen gas flow rate of 200 mL / min and a heating rate of 10 ° C. / min. As a result, the weight of the crushed material decreased as the temperature increased. The weight of the crushed material at the temperature at the start of the measurement (45 ° C.) was taken as 100 wt%, and the temperature at which the weight of the crushed material decreased to 95 wt% (5% weight loss temperature) was determined.

[0092]

[0093] (Measurement of Glass Transition Temperature (Tmg)) The glass transition temperatures of the cast plates produced in Examples 2 and 4 and Comparative Example 1 were measured by the following method. The results are shown in Table 2.

[0094] The cast plate was crushed to a diameter or length of each side of 0.5 mm or less, and the resulting crushed material was used as a sample. The glass transition temperature (°C) was measured in accordance with JIS-K7121. The glass transition temperature was measured using a differential scanning calorimeter ("DSC7020" manufactured by Hitachi High-Tech Science Corporation) at a nitrogen gas flow rate of 50 mL / min. Specifically, the sample was heated from room temperature (23°C) to 150°C at a rate of 20°C / min (first heating), and then held at 150°C for 5 minutes to completely melt the sample. The sample was then cooled from 150°C to -35°C at a rate of 10°C / min and held at -35°C for 1 minute. The sample was then heated again to 210°C at a rate of 10°C / min (second heating).

[0095] Of the DSC curves obtained from the above temperature profile, the intersection of the step-change partial curve during the second temperature rise and the straight lines equidistant in the vertical direction from the two baseline extensions (midpoint glass transition temperature) was taken as the glass transition temperature (°C).

[0096]

[0097] As shown in Tables 1 and 2, the cast plates made from the compositions containing methyl methacrylate, methyl pivalate, and water had a higher 5% weight loss temperature or glass transition temperature than the cast plates made from the compositions containing methyl methacrylate and methyl pivalate but not water, and exhibited excellent heat resistance.

[0098] Reference Examples 1 to 4 Compositions were prepared by adding methyl pivalate to methyl methacrylate in the amounts shown in Table 3. The compositions were subjected to the same storage test as in the Examples. Cast plates were prepared using the compositions after the storage test in the same manner as in the Examples, and the residual MMA concentration of the cast plates was measured by the method described below. The results are shown in Table 3.

[0099] (Measurement of Residual MMA Concentration) 0.5 g was cut from the cast plate 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 obtained acetone solution and stirred. 30 cc of methanol was added to the obtained mixed solution to reprecipitate the methyl methacrylate polymer. The supernatant solution was then collected as a sample solution. The amount of residual methyl methacrylate contained in the sample solution was measured using the following gas chromatography apparatus.

[0100] (Measurement conditions) Apparatus: GC-2010 Plus (Shimadzu Corporation) Column: DB-1 (Agilent Technologies, Inc.) Detector: FID 2010 Plus (Shimadzu Corporation) Column oven conditions Initial temperature: 40°C (hold time 1 min) Heating rate: 8°C / min Intermediate temperature: 120°C (hold time 0 min) Heating rate: 20°C / min Final temperature: 250°C (hold time 5 min) Sample vaporization conditions Vaporization chamber temperature: 300°C Carrier gas: Helium Pressure: 50 kPa Total flow rate: 58.3 mL / min Column flow rate: 1.08 mL / min Linear velocity: 31.1 cm / sec Purge dose: 3.0 mL / min Split ratio: 50 Detector conditions Detector temperature: 300°C Sampling rate: 40 msec Make-up gas: N ２ Make-up flow rate: 30 mL / min H2 flow rate: 40 mL / min Air flow rate: 400 mL / min Autosampler conditions Injection volume: 1 μL

[0101] 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, and the peak area ratio A (=a1 / b1) was calculated from these peak areas.

[0102] A standard sample having 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. The factor f (= W0 / A0) was then calculated from the peak area ratio A0 and the mass ratio W0.

[0103] Next, the mass ratio W of methyl methacrylate to methyl isobutyl ketone contained in the sample solution 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.

[0104]

[0105] As shown in Table 3, the cast plates of Reference Examples 2 to 4, which were made using a composition in which methyl pivalate was added to methyl methacrylate, had a lower residual MMA concentration and exhibited superior durability compared to the cast plate made using the composition of Reference Example 1 in which methyl pivalate was not added to methyl methacrylate.

Claims

1. A composition comprising methyl methacrylate, methyl pivalate, and water, wherein the concentration of methyl pivalate is greater than 0 ppm by mass and not greater than 10,000 ppm by mass of the total composition, and the concentration of water is greater than 0 ppm by mass and not greater 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. The composition of claim 1, wherein the methyl methacrylate comprises recycled methyl methacrylate or bio-sourced methyl methacrylate.

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

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

7. A polymer containing structural units derived from methyl methacrylate contained in the composition according to any one of claims 1 to 6.

8. A molded article comprising the polymer according to claim 7.

9. A cured product of the composition according to any one of claims 1 to 6.

10. A molded article comprising the cured product according to claim 9.

11. 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 6.

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