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

Abstract

The present invention addresses the problem of providing: a composition capable of controlling thermal decomposability of a molded body; a polymer obtained by using the composition; a cured product and a molded body; and a method for producing polymethyl methacrylate.　The present invention relates to: a composition containing methyl methacrylate, methyl pivalate, and methyl isobutyrate, wherein the content of methyl pivalate in the composition is more than 0 ppm by mass and 50000 ppm by mass or less, and the content of methyl isobutyrate in the composition is more than 0 ppm by mass and 2000 ppm by mass or less; a polymer obtained using the composition; a cured product; a molded body; and a method for producing polymethyl methacrylate obtained by polymerizing methyl methacrylate in the 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 product, and a method for producing polymethyl methacrylate.

[0002] Polymethyl(meth)acrylate, such as polymethyl methacrylate obtained by polymerizing methyl methacrylate, 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; 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 a polymer such as high-quality polymethyl methacrylate, 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] Incidentally, for molded articles intended for chemical recycling after use, the required quality level according to the application is becoming higher. On the other hand, if the thermal stability, among other qualities, of the molded article is too high, the suitability for recycling processing will be poor. Therefore, when it comes to the quality of molded articles containing polymethyl (meth)acrylate, it is important to consider the required level according to the application and the suitability for recycling processing, and to achieve a good balance between these. As an indicator of such quality, the thermal decomposition rate of the molded article is attracting attention.

[0007] In view of the above circumstances, an object of the present disclosure is to provide a composition capable of controlling the thermal decomposition of a molded article, a polymer, a cured product, and a molded article obtained using the composition, and a method for producing polymethyl methacrylate.

[0008] Means for solving the above problems include the following embodiments. <1> A composition containing methyl methacrylate, methyl pivalate, and methyl isobutyrate, wherein the content of the methyl pivalate in the entire composition is more than 0 ppm by mass and not more than 50,000 ppm by mass, and the content of the methyl isobutyrate in the entire composition is more than 0 ppm by mass and not more than 2,000 ppm by mass. <2> The composition according to <1>, wherein the content of the methyl methacrylate in the entire composition is 85% by mass or more. <3> The composition according to <1> or <2>, wherein the content of the methyl methacrylate in the entire composition is 90% by mass or more. <4> The composition according to any one of <1> to <3>, wherein the content of the methyl isobutyrate is less than 2,000 ppm by mass. <5> The composition according to any one of <1> to <4>, wherein the methyl methacrylate includes recycled methyl methacrylate or bio-derived methyl methacrylate. <6> The composition according to any one of <1> to <5>, further comprising a (meth)acrylic acid ester other than methyl methacrylate. <7> A polymer comprising a structural unit derived from the methyl methacrylate contained in the composition according to any one of <1> to <6> above. <8> A molded article comprising the polymer according to <7> above. <9> A cured product of the composition according to any one of <1> to <6> above. <10> A molded article comprising the cured product according to <9> above. <11> A method for producing polymethyl methacrylate, comprising a step of polymerizing the methyl methacrylate contained in the composition according to any one of <1> to <6> above.

[0009] The present disclosure provides a composition capable of controlling the thermal decomposition of a molded article, a polymer, a cured product, and a molded article obtained using the composition, and a method for producing polymethyl methacrylate using the composition, for example.

[0010] FIG. 1 is a graph showing the relationship between the methyl isobutyrate content of the compositions prepared in the Examples (not stored after preparation) and the 5% weight loss temperature of cast plates formed from the compositions.

[0011] An embodiment of the present disclosure will be described below, but the present disclosure is not limited to the following embodiment. In the present disclosure and this specification, "(meth)acrylic" means one or both of acrylic and methacrylic. The same applies to "(meth)acrylic acid ester" and "(meth)acrylic acid." Furthermore, in the present disclosure and this specification, when describing content, physical properties, etc., by indicating a numerical range, if the upper and lower limits of the numerical range are described separately, any of the upper and lower limits can be appropriately combined to form a specific numerical range. On the other hand, when describing multiple numerical ranges expressed using "to", the upper and lower limits forming the numerical range are not limited to the specific combination written before and after "to" as a specific numerical range, but can be a numerical range obtained by appropriately combining the upper and lower limits of each numerical range. Note that in the present disclosure and this specification, a numerical range expressed using "to" means a range that includes the numerical values ​​written before and after "to" as the upper and lower limits.

[0012] <Composition> The composition of the present disclosure (the composition in one embodiment of the present disclosure) contains methyl methacrylate, methyl pivalate, and methyl isobutyrate, wherein the content of methyl pivalate in the entire composition is more than 0 ppm by mass and not more than 50,000 ppm by mass, and the content of methyl isobutyrate in the entire composition is more than 0 ppm by mass and not more than 2,000 ppm by mass.

[0013] As shown in the examples described below, by incorporating methyl pivalate and methyl isobutyrate into a composition containing methyl methacrylate and then setting the contents of methyl pivalate and methyl isobutyrate within the above-mentioned specific ranges, the 5% weight loss temperature of a molded article formed using the composition can be improved while maintaining the glass transition temperature of the molded article (polymer, specifically, a homopolymer or copolymer of methyl methacrylate). As a result, the composition of the present disclosure is resistant to thermal decomposition, and when formed into a molded article, it can impart the desired thermal stability and improve heat resistance. Meanwhile, the polymethyl methacrylate contained in a molded article formed using the composition of the present disclosure maintains thermal decomposition even when its thermal stability is enhanced. Therefore, when formed into a molded article, the composition of the present disclosure can achieve both high thermal stability and excellent recyclability after use, and the thermal decomposition of the molded article can be controlled.

[0014] (Methyl methacrylate) The composition of the present disclosure contains methyl methacrylate. In the present disclosure, compounds such as methyl methacrylate generally refer to compounds as a single component, but may contain inevitable impurities. In addition, in the present disclosure, each compound, particularly methyl methacrylate, can also be used as a mixture with methyl pivalate, methyl isobutyrate, other components (particularly low-content components) described below, solvents, etc., in addition to inevitable impurities, as long as the purpose of the present disclosure is not impaired and the composition, cured product, or molded product of the present disclosure meets the composition (components and contents).

[0015] The content of methyl methacrylate in the composition (of the entire composition) is not particularly limited and can be determined appropriately depending on the application of polymethyl methacrylate obtained using the composition, etc. The content of methyl methacrylate is not particularly limited, but is, for example, preferably 85% by mass or more of the entire composition (of the total mass of the composition), more preferably 90% by mass or more, and can also be 95% by mass or more or 99% by mass or more, in terms of maintaining excellent properties of polymethyl methacrylate, its molded body, etc.

[0016] The methyl methacrylate contained in the composition may include methyl methacrylate synthesized by a known synthesis method (sometimes referred to as "synthetic methyl methacrylate"). The synthesis method is not particularly limited, and may be any of the ACH method, the C4 direct oxidation method, and the Alpha method.

[0017] 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 performed, for example, by heating polymethyl methacrylate to a temperature equal to or higher than its thermal decomposition temperature. 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.

[0018] The methyl methacrylate contained in the composition may include bio-derived methyl methacrylate. In the present disclosure, "bio-derived methyl methacrylate" means 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, but a raw material derived from vegetable oil is preferred.

[0019] The methyl methacrylate contained in the composition of the present disclosure may include at least one of synthetic methyl methacrylate, recycled methyl methacrylate, and bio-derived methyl methacrylate. From the perspective of addressing the above-mentioned rising resource prices and environmental issues, the composition of the present disclosure preferably includes at least one of recycled methyl methacrylate and bio-derived methyl methacrylate as the methyl methacrylate. Note that, in the present disclosure, the content of each of synthetic methyl methacrylate, recycled methyl methacrylate, and bio-derived methyl methacrylate relative to the total mass of methyl methacrylate contained in the composition of the present disclosure is not particularly limited and can be determined as appropriate.

[0020] (Methyl pivalate) The composition of the present disclosure contains methyl pivalate. The content of methyl pivalate in the entire composition is greater than 0 ppm by mass and 50,000 ppm by mass or less, relative to the total mass of the composition. In the composition of the present disclosure, the coexistence of methyl pivalate and methyl isobutyrate (described later) at a predetermined content relative to methyl methacrylate can improve the storage stability of the composition or the thermal stability of a molded article.

[0021] The content of methyl pivalate in the entire composition can be appropriately determined within the above range. For example, from the viewpoint of the storage stability of the composition and / or the control of the thermal decomposition of the molded article, the content 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 composition.

[0022] On the other hand, the upper limit of the content of methyl pivalate in the entire composition can be appropriately determined within the above range, and can be, for example, 2000 ppm by mass or less, preferably 1000 ppm by mass or less, and more preferably 600 ppm by mass or less.

[0023] (Methyl isobutyrate) The composition of the present disclosure contains methyl isobutyrate. The content of methyl isobutyrate in the entire composition is greater than 0 ppm by mass and not more than 2000 ppm by mass, relative to the total mass of the composition. In the composition of the present disclosure, the coexistence of methyl isobutyrate and methyl pivalate at a predetermined content relative to methyl methacrylate can improve the storage stability of the composition or the thermal stability of a molded article.

[0024] The content of methyl isobutyrate in the entire composition can be appropriately determined within the above range. For example, from the viewpoint of the storage stability of the composition and / or the viewpoint of controlling the thermal decomposition of a molded article, the content 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 composition.

[0025] On the other hand, the upper limit of the methyl isobutyrate content in the entire composition can be appropriately determined within the above range. For example, from the viewpoint of increasing the 5% weight loss temperature of the molded body to control thermal decomposition (enhancing thermal stability), the upper limit can be set to less than 2000 ppm by mass, relative to the total mass of the composition. Taking into consideration the thermal decomposition of the molded body, the upper limit is preferably 1800 ppm by mass or less, more preferably 1500 ppm by mass or less, and even more preferably 1000 ppm by mass or less.

[0026] The composition of the present disclosure may contain components other than methyl methacrylate, methyl pivalate, and methyl isobutyrate (hereinafter, sometimes referred to as "other components"). Examples of other components include (meth)acrylic acid esters, polymers described below, low-content components, and additives.

[0027] ((Meth)acrylic acid ester) The composition of the present disclosure may contain a (meth)acrylic acid ester other than methyl methacrylate (also simply referred to as "(meth)acrylic acid ester"). The (meth)acrylic acid ester is not particularly limited, and examples thereof include methyl acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, sec-butyl (meth)acrylate, tert-butyl (meth)acrylate, cyclohexyl (meth)acrylate, benzyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, and cyclopentanyl (meth)acrylate. Among these, methyl acrylate or ethyl acrylate is preferred, and methyl acrylate is more preferred. The composition of the present disclosure may contain one type of (meth)acrylic acid ester, or may contain two or more types of (meth)acrylic acid esters. The (meth)acrylic acid ester contained in the composition of the present disclosure is usually one that is (intentionally) mixed separately from the above-mentioned methyl methacrylate, etc., but it may also be a by-product produced during the synthesis of methyl methacrylate or the regeneration treatment of polymethyl methacrylate.

[0028] When the composition of the present disclosure contains a (meth)acrylic acid ester, its content is not particularly limited and can be determined appropriately.For example, the upper limit of the content of the (meth)acrylic acid ester is preferably 50,000 mass ppm or less, more preferably 40,000 mass ppm or less, and even more preferably 30,000 mass ppm or less, based on the total composition.On the other hand, the lower limit of the content of the (meth)acrylic acid ester can be 1 mass ppm or more, 2 mass ppm or more, or 5 mass ppm or more, based on the total composition.

[0029] (Low Content Components) The composition of the present disclosure may contain low content components other than methyl pivalate and methyl isobutyrate. The low content components may be contained in the composition as by-products generated during the production of methyl methacrylate or the regeneration process of polymethyl methacrylate. In the present disclosure, the term "low content components" refers to components contained in the composition at a content of 10,000 ppm by mass or less. However, the (meth)acrylic acid esters and the additives described below are not included in the low content components even if their content in the composition is 10,000 ppm by mass or less.

[0030] Examples of low content components include carboxylic acid ester compounds, aromatic hydrocarbon compounds, aliphatic hydrocarbon compounds, alcohol compounds, etc. The composition of the present disclosure may contain only one type of low content component, or two or more types of low content components.

[0031] Examples of carboxylic acid ester compounds include 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. Examples of aromatic hydrocarbon compounds include toluene and styrene. Examples of aliphatic hydrocarbon compounds include 1-octene and 1-octadecene. Examples of alcohol compounds include methanol, ethanol, propanol (including isomers), and butanol (including isomers).

[0032] When the composition of the present disclosure contains a low content component, the content of each compound group is not particularly limited and can be determined appropriately.For example, the upper limit of the content of each compound group is preferably 8000 mass ppm or less, more preferably 6000 mass ppm or less, and even more preferably 5000 mass ppm or less of the total composition.On the other hand, the lower limit of the content of each compound group can be 1 mass ppm or more, 2 mass ppm or more, or 5 mass ppm or more of the total composition.

[0033] (Additives) The composition of the present disclosure may contain additives as needed. The additives are not particularly limited, and examples thereof include a release agent, a polymerization regulator, a polymerization initiator, an ultraviolet absorber, and a colorant. The composition of the present disclosure may contain one or more additives.

[0034] Examples of release agents 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 release agents include sodium di-(2-ethylhexyl)sulfosuccinate, stearyl alcohol, methyl stearate, and stearic acid amide. The composition of the present disclosure may contain one or more types of release agents. The content of the release agent is not particularly limited and can be determined as appropriate, and may be, for example, 0.01 to 1.0% by mass of the total composition.

[0035] As the polymerization regulator (an additive that controls the polymerization rate in a polymerization reaction), any suitable polymerization regulator known in the art can be used. Examples of such polymerization regulators include compounds that can control 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. The composition of the present disclosure may contain one or more polymerization regulators. The content of the polymerization regulator is not particularly limited and can be determined appropriately, and can be, for example, 0.001 to 0.5% by mass of the total composition.

[0036] Examples of the polymerization initiator include a radical polymerization initiator, a diacyl peroxide initiator, a dialkyl peroxide initiator, a peroxyester initiator, a percarbonate initiator, and a peroxyketal initiator.

[0037] Specific examples of the radical polymerization initiator 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).

[0038] Specific examples of diacyl peroxide initiators and dialkyl peroxide initiators include, for example, dicumyl peroxide, tert-butylcumyl peroxide, di-tert-butyl peroxide, benzoyl peroxide, and lauroyl peroxide.

[0039] 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.

[0040] Specific examples of percarbonate initiators include tert-butylperoxyallyl carbonate and tert-butylperoxyisopropyl carbonate.

[0041] 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.

[0042] The composition of the present disclosure may contain one or more polymerization initiators. The content of the polymerization initiator is not particularly limited and can be determined appropriately, and can be, for example, 0.01 to 5% by mass of the total composition.

[0043] Examples of UV absorbers include benzophenone UV absorbers, cyanoacrylate UV absorbers, benzotriazole UV absorbers, malonic acid ester UV absorbers, and oxalanilide UV absorbers. Specific examples of UV 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. The composition may contain one or more UV absorbers. The content of the UV absorber is not particularly limited and can be determined as appropriate, for example, from 0.001 to 1% by mass of the total composition.

[0044] Examples of colorants 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. The colorant contained in the composition of the present disclosure may be one type or two or more types. The content of the colorant is not particularly limited and can be determined appropriately, for example, when the content of the colorant is 1.0 × 10 of the total composition. －８ It can be up to 0.5% by mass.

[0045] When the composition of the present disclosure contains two or more additives, their total content is not particularly limited and can be determined appropriately.The upper limit of the total content of the additives can be, for example, 15% by mass or less of the total composition, but can also be appropriately set to 10% by mass or less, 5% by mass or less, or 1% by mass or less.On the other hand, the lower limit of the total content of the additives can be, for example, 0.01% by mass or more of the total composition, but can also be appropriately set to 0.05% by mass or more or 0.1% by mass or more.

[0046] (Preparation of Composition) The composition of the present disclosure can be produced by known methods and can typically be prepared by mixing methyl methacrylate, methyl pivalate, methyl isobutyrate, and other components as appropriate in the proportions that result in the above-mentioned respective contents. The mixing method is not particularly limited, and the components may be mixed all at once or sequentially. When mixed sequentially, the order of mixing is not particularly limited. Furthermore, the mixing conditions are not particularly limited and can be determined as appropriate, but it is preferable to select conditions that suppress the evaporation of methyl isobutyrate and the like. In the present disclosure, as described above, methyl pivalate, methyl isobutyrate, and other components can also be used as a mixture with methyl methacrylate, and in this case, the amount of methyl pivalate and the like mixed is determined taking into account the content in the mixture with methyl methacrylate used. Note that, with respect to methyl pivalate and the like, if the content in the mixture with methyl methacrylate used satisfies the content in the composition of the present disclosure, there is no need to deliberately adjust the content of methyl pivalate and the like.

[0047] The composition of the present disclosure may be used immediately after preparation, or may be stored before use. Because the composition of the present disclosure exhibits excellent storage stability, one preferred embodiment is to store the composition after preparation and then use it. The storage conditions for storing the composition of the present disclosure are not particularly limited, but the storage temperature can be, for example, 0 to 45°C. From the viewpoint of ensuring good quality, the storage temperature is preferably selected from the range of 0 to 39°C, more preferably from the range of about 25°C ± 10°C, and even more preferably from the range of about 25 to 30°C. The storage time can be determined appropriately depending on the state, quality, etc. of the composition of the present disclosure.

[0048] <Polymer, Cured Product, and Molded Article> 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. Examples of other polymerization components include the above-mentioned (meth)acrylic acid esters. The polymer of the present disclosure is preferably polymethyl methacrylate. This polymethyl methacrylate is produced by the method for producing polymethyl methacrylate of the present disclosure described below. 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.

[0049] 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 a composition and may contain components that are not involved in polymerization. However, depending on the method for curing the composition and the composition of the composition, it may be considered the same as the polymer of the present disclosure described above (i.e., it does not contain components that are not involved in polymerization). In the present disclosure, the curing method may be any method that is normally applied to compositions, including polymerization methods and crosslinking methods, with polymerization methods being preferred. The properties of the cured product of the present disclosure are not particularly limited, but it is usually a non-molded product that is not molded into a predetermined shape. The cured product of the present disclosure is produced by the method for producing a cured product described below.

[0050] 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 of the present disclosure will include a polymer of the composition of the present disclosure. The molded article of the present disclosure is preferably a molded article containing a cured product obtained by curing only the composition of the present disclosure. The molded article is an object obtained by molding a polymer or cured product into a form, shape, and dimensions suitable for the intended use using various known molding methods. Examples of shapes include sheet-like shapes (including film-like, strip-like, and plate-like shapes, which may be long or short (leaf-like)), block-like shapes, and various three-dimensional shapes. The molded article of the present disclosure is manufactured by the molded article manufacturing method described below.

[0051] In the cured product and molded article of the present disclosure, the content of the polymer of the present disclosure can be appropriately determined depending on the content of methyl methacrylate in the composition of the present disclosure, the curing conditions of the composition, the molding conditions, etc. In one embodiment, the cured product or molded article of the present disclosure may contain (remain) residual (unpolymerized) methyl methacrylate, methyl pivalate, methyl isobutyrate, and other components. In another embodiment of the molded article of the present disclosure, it is preferable that the remaining components are removed to an extent that satisfies the required properties of the application.

[0052] In one embodiment of the present disclosure, when the cured product or molded product of the present disclosure contains methyl pivalate, the content of methyl pivalate is not particularly limited and can be, for example, more than 0 ppm by mass and 50,000 ppm by mass or less, relative to the total mass (100 parts by mass) of the cured product or molded product. From the viewpoint of controlling the thermal decomposition property of the molded product, for example, from the viewpoint of increasing the thermal decomposition property of the cured product or molded product, the content of methyl pivalate is, for example, 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 cured product or molded product. On the other hand, from the viewpoint of increasing the 5% weight loss temperature of the cured product or molded product, the content of methyl pivalate can be, for example, 2,000 ppm by mass or less, preferably 1,000 ppm by mass or less, and more preferably 600 ppm by mass or less, relative to the total mass of the cured product or molded product.

[0053] In one embodiment of the present disclosure, when the cured product or molded product of the present disclosure contains methyl isobutyrate, the content of methyl isobutyrate is not particularly limited and can be, for example, more than 0 ppm by mass and 2000 ppm by mass or less, relative to the total mass (100 parts by mass) of the cured product or molded product. From the viewpoint of controlling the thermal decomposition property of the molded product, for example, from the viewpoint of increasing the thermal decomposition property of the cured product or molded product, the content of methyl isobutyrate is, for example, 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 cured product or molded product. On the other hand, from the viewpoint of increasing the 5% weight loss temperature of the cured product or molded product, the content of methyl isobutyrate can be, for example, 2000 ppm by mass or less, preferably less than 2000 ppm by mass, more preferably 1800 ppm by mass or less, even more preferably 1500 ppm by mass or less, and particularly preferably 1000 ppm by mass or less, relative to the total mass of the cured product or molded product.

[0054] When the cured product or molded article of the present disclosure contains the other components described above, the content of each component is not particularly limited and can be set, for example, within the same range as the content of each component in the entire composition, except for components that decompose or volatilize during polymerization or molding, such as polymerization regulators and polymerization initiators.

[0055] Whether or not the cured product or molded article of the present disclosure contains methyl methacrylate, methyl pivalate, methyl isobutyrate, and other components can be determined by known analytical methods. Examples of known analytical methods include gas chromatography and liquid chromatography. Note that whether or not 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.

[0056] The 5% weight loss temperature of the molded product is measured by the method described in the Examples. Note that the following is an example of the measurement method, and the measurement may be performed 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 temperature or rate of heating are appropriately changed so that the 5% weight loss temperature can be measured) or by another known method.

[0057] (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.

[0058] <Methods for Producing Polymers, Cured Products, and Molded Articles> A method for producing a polymer (polymethyl methacrylate) according to the present disclosure includes a step of polymerizing methyl methacrylate contained in the composition according to the present disclosure. The method for polymerizing methyl methacrylate contained in the composition according to the present disclosure is not particularly limited and may be any known method, such as bulk polymerization, solution polymerization, suspension polymerization, or emulsion polymerization. In the polymerization step, other polymerization components may be copolymerized when polymerizing methyl methacrylate contained in the composition according to the present disclosure. The method for producing a polymer according to the present disclosure is not limited to a method in which the polymerization step is carried out using a pre-prepared composition according to the present disclosure, as long as methyl pivalate and methyl isobutyrate are present in a predetermined content (mixing amount) when polymerizing methyl methacrylate. For example, a method for producing a polymer according to the present disclosure includes a method in which, without pre-preparing the composition according to the present disclosure, methyl pivalate and methyl isobutyrate are mixed with methyl methacrylate in a predetermined mixing amount to form a polymerization system corresponding to the composition according to the present disclosure, and then methyl methacrylate is polymerized. Therefore, in this disclosure and this specification, when referring to a polymer obtained using the composition of the present disclosure or a polymer formed using the composition of the present disclosure, as described above, it includes polymers obtained in at least two embodiments, namely, an embodiment in which the composition of the present disclosure is used and an embodiment in which the composition of the present disclosure is formed in a polymerization system. This also applies to the cured product and molded article described below.

[0059] The cured product of the present disclosure can be produced by any known method and under any known conditions depending on the curing method, etc., and can be produced, for example, by the polymerization step described above.

[0060] The molded article of the present disclosure can be produced by various known molding methods. For example, the composition of the present disclosure can be bulk polymerized to polymerize and mold methyl methacrylate in the composition of the present disclosure to produce a sheet-shaped molded article. In addition, in cell-cast polymerization, the composition of the present disclosure can be heat-treated under predetermined heating conditions to allow the polymerization reaction to proceed, thereby obtaining a molded article in which the composition is cured.

[0061] 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, for example, taking into consideration the type and content of the selected polymerization regulator, polymerization initiator, and / or other components. In cell cast polymerization, the heating temperature can be, for example, 50 to 130°C. The heating time can be, for example, 1 to 20 hours. The heat treatment can also include multiple steps with different heating temperatures and / or heating times. A molded article produced by cell cast polymerization can be produced, for example, by performing heat treatment under heating conditions including steps C1 to C7 described in the Examples below. This heat treatment suppresses heat generation during the polymerization reaction and allows the polymerization to be completed stably.

[0062] When the composition of the present disclosure is subjected to the 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.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] The cured product and molded article of the present disclosure can be melt-kneaded after appropriate crushing treatment, etc., to recover the polymer (polymethyl methacrylate) (material recycling). Examples of conditions for melt-kneading include kneading at a temperature at which the polymer (polymethyl methacrylate) melts. The polymer (polymethyl methacrylate), cured product, and molded article of the present disclosure can be thermally decomposed (depolymerized) to recover the methyl (meth)acrylate (chemical recycling). The conditions for thermal decomposition are not particularly limited, and examples include heating to 380 to 500°C.

[0068] <Applications of Polymer, Cured Product, and Molded Product> The polymer (polymethyl methacrylate), cured product, and molded product obtained from the composition of the present disclosure each 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 to heat and light sources, such as lighting fixtures, automobile parts, signs, and building materials.

[0069] Hereinafter, embodiments of the present disclosure will be described based on examples, but the present disclosure is not limited to the following examples.

[0070] Example 1 (Preparation of Composition) Composition 1 was prepared by adding 0.03% by mass of methyl pivalate (manufactured by Tokyo Chemical Industry Co., Ltd.) and 0.01% by mass of methyl isobutyrate (manufactured by Tokyo Chemical Industry Co., Ltd.) to 99.96% by mass of methyl methacrylate and mixing them at room temperature (25°C). The obtained composition 1 was liquid at room temperature and under 0.1 MPa (1 atm). The composition of composition 1 (the content of methyl pivalate and methyl isobutyrate) is also shown in Table 1. Composition 1 corresponds to the composition of the present disclosure (not stored after preparation).

[0071] 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 a test to evaluate stability after long-term storage, and was carried out under accelerated conditions (60°C).

[0072] Step 1: 25 mL of the composition was poured into the bottom of a pressure vessel ("TVS-N2 type" manufactured by Taiatsu Glass Industry Co., Ltd.). Step 2: A gasket was placed between the top and bottom of the pressure vessel, and the pressure vessel was sealed. Step 3: Nitrogen was fed from the top tip of the pressure vessel, and the vessel was sealed with an internal pressure of 0.2 MPa, and it was confirmed that the internal pressure did not change for 1 minute. Step 4: The internal pressure in the pressure vessel was removed, and a stopcock was attached to the top tip of the pressure vessel. Step 5: The pressure vessel was placed in an oil bath set to 60°C. Step 6: The pressure vessel was stored in the oil bath for 24 hours. Step 7: After 24 hours had passed, the pressure vessel was removed from the oil bath and placed in ice-cold water to rapidly cool it.

[0073] Next, composition 1' (99.84 parts by mass), sodium di-(2-ethylhexyl)sulfosuccinate (0.05 parts by mass) as a mold release agent, terpinolene (0.013 parts by mass) as a polymerization regulator, and 2,2'-azobisisobutyronitrile (0.08 parts by mass) as a polymerization initiator were mixed at room temperature to obtain composition 1" for forming a molded body (cast plate). The obtained composition 1" was liquid at room temperature and under 0.1 MPa (1 atm). Note that composition 1' and composition 1" correspond to the compositions (after storage test) of the present disclosure.

[0074] (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, forming 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 containing Composition 1″ was placed in an oven, and heat treatment was carried out under heating conditions including the following steps C1 to C7 in this order, thereby polymerizing Composition 1″. A 3 mm thick, 100 mm square cast plate 1 was produced as a molded product of a cured product containing methyl methacrylate as a polymer. Steps C1 to C7 below were carried out in this order to suppress heat generation during the polymerization reaction and ensure stable completion of the polymerization.

[0075] Step C1: The temperature was raised from room temperature to 68°C over 20 minutes. Step C2: 68°C was maintained for 90 minutes. Step C3: The temperature was lowered from 68°C to 64°C over 20 minutes. Step C4: 64°C was maintained for 90 minutes. Step C5: The temperature was raised from 64°C to 123°C over 10 minutes. Step C6: 123°C was maintained for 120 minutes. Step C7: The temperature was lowered from 123°C to room temperature over 90 minutes.

[0076] (Measurement of 5% weight loss temperature) 9.3 mg of the pulverized material obtained by pulverizing the cast plate 1 to a diameter or length of each side of 0.5 mm or less 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 pulverized material was measured while heating from 45 ° C. to 520 ° C. under conditions of a nitrogen gas flow rate of 200 mL / min and a heating rate of 10 ° C. / min. As a result, the weight of the pulverized material decreased as the temperature increased. The weight of the pulverized 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 pulverized material decreased to 95 wt% (5% weight loss temperature) was determined. A higher 5% weight loss temperature indicates a higher thermal stability of the polymer. The results are shown in Table 1 and FIG.

[0077] Examples 2 and 3, Comparative Example 1 Compositions 2, 3, and C1 (2′, 2″, 3′, 3″, C1′, C1″) and cast plates 2, 3, and C1 of Examples 2 and 3 and Comparative Example 1 were produced in the same manner as in Example 1, except that the amount of methyl isobutyrate mixed in Example 1 was changed to the value shown in Table 1 and the amount of methyl methacrylate mixed in was changed accordingly so that the total mixed amount was 100% by mass, and the resulting compositions were used. The 5% weight loss temperatures of cast plates 2, 3, and C1 were measured in the same manner as in Example 1. The results are shown in Table 1 and FIG. 1 .

[0078]

[0079] As is clear from the results shown in Table 1 and Figure 1, the composition of Comparative Example 1, which contains methyl methacrylate and a specified amount of methyl pivalate but does not contain methyl isobutyrate, exhibits a low 5% weight loss temperature when molded under the above conditions. Therefore, while the composition of Comparative Example 1 is susceptible to thermal decomposition and is suitable for chemical recycling, it is unable to produce molded products with sufficient thermal stability. In contrast, the compositions of Examples 1 to 3, which contain a specified amount of methyl pivalate and methyl isobutyrate relative to methyl methacrylate, exhibit a high 5% weight loss temperature when molded and have excellent thermal stability even when stored under the above conditions, and are also capable of material recycling and chemical recycling via thermal decomposition. That is, the compositions of Examples 1 to 3 can achieve both high thermal stability and excellent recyclability after use when molded into molded products, making it possible to control the thermal decomposition of the molded products. Furthermore, the compositions of Examples 1 to 3 also exhibit excellent storage stability, as they are able to control the thermal decomposition of molded products even when stored under the above conditions. Furthermore, from the above results, it can be seen that when a composition containing methyl methacrylate contains methyl pivalate and methyl isobutyrate at predetermined contents, similar results can be obtained even when recycled methyl methacrylate or bio-derived methyl methacrylate is used as the methyl methacrylate.

Claims

1. A composition containing methyl methacrylate, methyl pivalate, and methyl isobutyrate, wherein the content of the methyl pivalate in the entire composition is greater than 0 ppm by mass and not more than 50,000 ppm by mass, and the content of the methyl isobutyrate in the entire composition is greater than 0 ppm by mass and not more than 2,000 ppm by mass.

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

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

4. The composition of claim 1, wherein the content of methyl isobutyrate is less than 2000 ppm by weight.

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

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

7. A polymer containing structural units derived from the 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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