Method for recovering methyl methacrylate-containing composition and methacrylic resin composition

Abstract

An object of the present invention is to effectively recover a methyl methacrylate-containing composition from an acrylic resin comprising a methyl methacrylate copolymer containing a crosslinked portion, a non-crosslinked methyl methacrylate copolymer, and an inorganic filler. [Solution] A method for recovering a methyl methacrylate-containing composition, comprising: thermally decomposing, in an extruder, a composition (1) containing 5 to 80 parts by weight of an inorganic filler per 100 parts by weight of the total of the methyl methacrylate copolymer (A) containing a crosslinked portion and the non-crosslinked methyl methacrylate copolymer (B), in which the weight ratio of A:B is 95:5 to 5:95, to obtain a methyl methacrylate-containing composition.

Description

[Technical field]

[0001] The present invention relates to a method for recovering a methyl methacrylate-containing composition from a methyl methacrylate copolymer, and a methacrylic resin composition obtained by using the recovered methyl methacrylate-containing composition. [Background technology]

[0002] The need for recycling synthetic resins derived from petroleum is increasing in order to reduce the environmental burden. The most widely known types of recycling are mechanical recycling, in which the resin is processed by thermal melting again, and chemical recycling, in which the monomer obtained by depolymerization through pyrolysis is reused. Methyl methacrylate copolymers are often used from the viewpoint of design and weather resistance due to their excellent transparency, but in mechanical recycling, the scope of recycling is limited in terms of the need to select compounds such as additives, the deterioration of design due to the presence of impurities, and the deterioration of the physical properties of the polymer due to thermal history when used as a recycled material. On the other hand, chemical recycling has the advantage that the physical properties of the methyl methacrylate copolymer when polymerized using the monomers can be made equivalent to the physical properties of the copolymer using non-recycled monomers and the physical properties before recycling by depolymerizing the monomers into monomers.

[0003] On the other hand, methyl methacrylate copolymers are known to be resins that are easier to depolymerize than other resins. However, no method is known for chemically recycling crosslinked methyl methacrylate copolymers, particularly those that contain inorganic fillers. In order to meet societal demands for petrochemistry, a method for recovering methyl methacrylate-containing compositions by chemical recycling is needed.

[0004] Patent Document 1 describes a method for recovering high-purity monomers by stabilizing the temperature during pyrolysis by coexisting methyl methacrylate copolymer waste with inorganic materials or metal powder using an externally heated rotary kiln.

[0005] Patent Document 2 describes a method for efficiently processing resin materials such as waste plastics by using a first extruder and a second extruder and setting their cylinder temperatures. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 1370656 [Patent Document 2] JP 2024-1935 A Summary of the Invention [Problem to be solved by the invention]

[0007] Patent Document 1 does not disclose the use of an extruder as a pyrolysis device. In addition, the details of the methyl methacrylate copolymer to be pyrolyzed are not disclosed, and general-purpose non-crosslinked PMMA is assumed.

[0008] Patent Document 2 relates to an apparatus for pyrolyzing resin, but does not disclose details of the raw materials for pyrolysis.

[0009] Therefore, an object of the present invention is to provide a method for effectively recovering a methyl methacrylate-containing composition from an acrylic resin comprising a methyl methacrylate copolymer containing a crosslinked portion, a non-crosslinked methyl methacrylate copolymer, and an inorganic filler. [Means for solving the problem]

[0010] In order to solve the above problems, the present inventors have conducted extensive research and have found that the problems can be solved by the following means.

[0011] [1] A method for recovering a methyl methacrylate-containing composition, comprising: thermally decomposing, in an extruder, a composition (1) containing 5 to 80 parts by weight of an inorganic filler per 100 parts by weight in total of a methyl methacrylate copolymer (A) containing a crosslinked portion and a non-crosslinked methyl methacrylate copolymer (B) in a weight ratio of A:B=95:5 to 5:95, to obtain a methyl methacrylate-containing composition. [2] The method for recovering a methyl methacrylate-containing composition according to [1], wherein the non-crosslinked methyl methacrylate copolymer (B) contains at least a component having a weight average molecular weight of 50,000 or more and less than 300,000. [3] A method for recovering a methyl methacrylate-containing composition according to [1] or [2], wherein the methyl methacrylate copolymer (A) containing the crosslinked portion is pulverized together with the inorganic filler (Property 1), and the non-crosslinked methyl methacrylate copolymer (B) is in one or more of the following forms (Property 2): pulverized, spherical powder, or pellets. [4] The method for recovering a methyl methacrylate-containing composition according to any one of [1] to [3], further comprising the step of containing 0.01 to 10% by weight of a spreading agent relative to 100% by weight of the combined weight of the methyl methacrylate copolymer (A) containing the crosslinked portion and the inorganic filler. [5] The method for recovering a methyl methacrylate-containing composition according to [3], wherein (Property 1) and (Property 2) are mixed by dry blending. [6] The method for recovering a methyl methacrylate-containing composition according to any one of [1] to [5], wherein the inorganic filler is made of aluminum hydroxide or silica. [7] A method for recovering a methyl methacrylate-containing composition according to any one of [1] to [6], comprising separating a residual component containing an uncracked component discharged from an outlet of the pyrolysis section of the extruder into a storage tank, and separating a gas containing recycled methyl methacrylate generated by pyrolysis into a recovery tank as a liquid component by cooling. [8] The inorganic component contained in the residue component described in [7] is an aluminum compound, and by firing the residue component, an aluminum oxide-containing composition from which the organic component has been removed is obtained. The method for recovering the methyl methacrylate-containing composition described in [7]. [9] The inorganic component contained in the residue component described in [7] is a silicon compound, and by firing the residue component, silica from which the organic component has been removed is obtained. The method for recovering the methyl methacrylate-containing composition described in [7].

[10] The method for recovering the methyl methacrylate-containing composition according to any one of [1] to [9], wherein the composition (1) is made of waste artificial marble.

[11] A methacrylic resin composition obtained using the methyl methacrylate-containing composition obtained by any one of [1] to

[10] . [Advantages of the Invention]

[0012] In the present invention, a method for effectively recovering a methyl methacrylate-containing composition from an acrylic resin composed of a methyl methacrylate copolymer containing a crosslinked portion, a non-crosslinked methyl methacrylate copolymer, and an inorganic filler can be provided. By improving the plasticity with a non-crosslinked methacrylic copolymer, a continuous process of thermal decomposition using an extruder is made possible. Further, in one aspect of the present invention, resource circulation of the inorganic component is also possible by firing the inorganic component. [Brief Description of the Drawings]

[0013] [Figure 1] FIG. 1 is a schematic diagram showing the recovery process of the methyl methacrylate-containing composition of the present embodiment. [Modes for Carrying Out the Invention]

[0014] Hereinafter, modes for carrying out the present invention (hereinafter referred to as "the present embodiment") will be described in detail. The present invention is not limited to the following embodiments, and various changes can be made and implemented within the scope of the gist thereof.

[0015] [Methyl methacrylate copolymer (A) containing crosslinked portions] The methyl methacrylate copolymer (A) containing the crosslinked portion (crosslinked portion) of this embodiment, unless otherwise specified, contains a structure (monomer unit) derived from a methyl methacrylate monomer as a monomer unit as a main component, and contains a structure derived from a monomer having a difunctional or higher (meth)acryloyl group for crosslinking. That is, the methyl methacrylate copolymer (A) has a portion crosslinked by this difunctional or higher (meth)acryloyl group as a crosslinked portion. In addition, the methyl methacrylate copolymer (A) may or may not contain a structure derived from a monomer having a radically polymerizable carbon-carbon double bond as another monomer unit.

[0016] The monomer having a bifunctional or higher (meth)acryloyl group is not particularly limited as long as it can be copolymerized with methyl methacrylate, and specific examples thereof include 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, 3-methyl-1,5-pentanediol diacrylate, 1,9-nonanediol diacrylate, dimethylol-tricyclodecane diacrylate, trimethylolpropane triacrylate, pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, 2-methacryloyloxyethyl acid phosphate, 1,6-hexanediol dimethacrylate, 1,9-nonanediol dimethacrylate, ethylene glycol dimethacrylate, diethylene Examples of the monomers include glycol dimethacrylate, triethylene glycol diacrylate, triethylene glycol dimethacrylate, glycerin dimethacrylate, 2-hydroxy-3-acryloyloxypropyl methacrylate, ethylene oxide adduct dimethacrylate of bisphenol A, ethylene oxide adduct diacrylate of bisphenol A, trimethylolpropane trimethacrylate, 2-hydroxy-3-acryloyloxypropyl methacrylate, pentaerythritol triacrylate, isocyanuric acid ethylene oxide modified diacrylate, isocyanuric acid ethylene oxide modified triacrylate, (caprolactone modified) isocyanurate multifunctional acrylate, etc. These may be used alone or in combination of two or more.

[0017] The methyl methacrylate copolymer (A) containing a crosslinked portion of the present embodiment may be used alone or in combination of two or more kinds.

[0018] [Non-crosslinked methyl methacrylate copolymer (B)] The non-crosslinked methyl methacrylate copolymer (B) of the present embodiment is a non-crosslinked methyl methacrylate copolymer (B). Unless otherwise specified, the non-crosslinked methyl methacrylate copolymer (B) may be composed of only methyl methacrylate monomer units, or may be composed of only methyl methacrylate monomer units and alkyl acrylate monomer units, or may further contain other monomer units such as other vinyl monomer units copolymerizable with methyl methacrylate.

[0019] The other monomer units may be vinyl monomers copolymerizable with methyl methacrylate. Specifically, they include alkyl methacrylates with an alkyl group having 2 to 18 carbon atoms; alkyl acrylates with an alkyl group having 1 to 3 carbon atoms; aromatic vinyl compounds such as styrene, α-methylstyrene, and styrene having a substituent on the benzene ring; vinyl cyanide compounds such as acrylonitrile and methacrylonitrile; maleic anhydride, maleimide, N-substituted maleimide, etc. These may be used alone or in combination of two or more. From the social perspective of recovering from the market and performing chemical recycling, it is preferable to contain an alkyl acrylate having an alkyl group with 1 to 4 carbon atoms rather than ease of availability.

[0020] The non-crosslinked methyl methacrylate copolymer (B) of the present embodiment may be used alone or in combination of two or more. However, from the viewpoint of extrudability in an extruder, it preferably contains a component having a weight average molecular weight of 50,000 or more and less than 300,000. When the object to be thermally decomposed is derived from artificial marble, a non-crosslinked methacrylic acid copolymer may be used as a thickener when producing artificial marble. In that case, from the viewpoints of thickening property and processability during the production of artificial marble, it is more preferable that the weight average molecular weight is 100,000 or more and less than 300,000.

[0021] [Inorganic filler] From a social perspective of collecting the inorganic filler from the market and chemically recycling it, it is preferable that the inorganic filler of this embodiment has a size of 100 nm to 10 mm in terms of ease of availability, and the shape is not important.

[0022] The composition of the inorganic filler is not particularly limited, and examples thereof include calcium carbonate, silica, talc, clay, glass flakes, glass fibers, mica, potassium titanate, alumina, aluminum hydroxide, aluminum hydroxide, antimony oxide, zinc compounds, carbon nanotubes, graphite, etc. These may be used alone or in combination of two or more. When the object to be thermally decomposed is derived from artificial marble, silica or aluminum hydroxide may be used as the inorganic filler.

[0023] [Composition (1)] The composition (1) of this embodiment has a weight ratio of methyl methacrylate copolymer (A) containing a crosslinked portion and non-crosslinked methyl methacrylate copolymer (B) of A:B=95:5 to 5:95, and contains 5 to 80 parts by weight of inorganic filler for a total of 100 parts by weight of methyl methacrylate copolymer (A) and non-crosslinked methyl methacrylate copolymer (B). The object of the present invention is to solve the chemical recycling of methyl methacrylate copolymers containing crosslinked bodies or inorganic fillers, so it is necessary to contain methyl methacrylate copolymer (A) and inorganic filler. Therefore, it is not preferable that the weight ratio of non-crosslinked methyl methacrylate copolymer (B) to methyl methacrylate copolymer (A) containing a crosslinked portion is in the range of A:B=4.9:95.1 to 0:100 because the significance of the object is weakened. During pyrolysis in an extruder, in order to increase the pyrolysis efficiency, it is preferable that the object to be pyrolyzed is plasticized by heat, that is, it is preferable that it exhibits extrudability. For these reasons, the weight ratio of the methyl methacrylate copolymer (A) to the non-crosslinked methyl methacrylate copolymer (B) is preferably A:B=90:10 to 5:95, more preferably 80:20 to 5:95. If the inorganic filler is 0 to 4.9 parts by weight per 100 parts by weight of the total of the methyl methacrylate copolymer (A) containing a crosslinked portion and the non-crosslinked methyl methacrylate copolymer (B), the significance of the object of the present invention is weakened, so this is not preferred, and from the viewpoint of extrudability, it is preferably 5 to 70 parts by weight, more preferably 5 to 60 parts by weight.

[0024] The properties of the methyl methacrylate copolymer (A) containing a crosslinked portion, the non-crosslinked methyl methacrylate copolymer (B) and the inorganic filler in the composition (1) are not particularly limited. For example, in the case of artificial marble, since the inorganic filler is present in a dispersed state in the methyl methacrylate copolymer (A) containing a crosslinked portion, it is preferable in terms of convenience of feeding into an extruder if the methyl methacrylate copolymer (A) containing a crosslinked portion is pulverized together with the inorganic filler. The non-crosslinked methyl methacrylate copolymer (B) may be pulverized together with the methyl methacrylate copolymer (A) and the inorganic filler, and may be in any form such as powder, beads, or pellets. It is more preferable that they are dry-blended before being fed into an extruder. Dry blending refers to a state in which both the methyl methacrylate copolymer (A) and the non-crosslinked methyl methacrylate copolymer (B) are mixed by physical stirring in a solid state before being melted or pyrolyzed. Dry blending can be performed using any method, such as a blender, a Henschel mixer, a tumbler, or manually, and by dry blending, the components of the methyl methacrylate copolymer (A) containing crosslinked portions, the inorganic filler, and the non-crosslinked methyl methacrylate copolymer (B) are uniformly mixed, ensuring stable extrudability, thereby stabilizing the recovery rate of the methyl methacrylate-containing composition and the yield of the methyl methacrylate-containing composition.

[0025] [Spreader] In order to ensure further stable extrudability, it is more preferable to use a spreading agent in addition to the methyl methacrylate copolymer (A) containing a crosslinked portion, the non-crosslinked methyl methacrylate copolymer (B) and the inorganic filler in the composition (1). The amount of the spreading agent is, for example, preferably 0.01 to 10% by weight, more preferably 0.01 to 3% by weight, based on 100% by weight of the total of the methyl methacrylate copolymer (A) containing a crosslinked portion and the inorganic filler. By setting the amount of the spreading agent to 10% by weight or less, the recovery rate of the methyl methacrylate-containing composition can be increased and impurities in thermal decomposition can be suppressed. On the other hand, by setting the amount of the spreading agent to 0.01% by weight, the solid dispersion is increased, the extrudability is more stable, the recovery rate of the methyl methacrylate-containing composition can be increased, and blockage by the inorganic filler in the extruder can be suppressed, thereby improving safety.

[0026] The composition of the spreading agent is not particularly limited, and one type may be used alone, or two or more types may be used in combination. Liquid paraffin is particularly preferred in terms of solid dispersion, suppression of unwanted side reactions during thermal decomposition, and ease of identification and separation.

[0027] The composition (1) may contain additives, such as ultraviolet absorbers, heat stabilizers, light stabilizers, plasticizers, flame retardants, flame retardant assistants, curing agents, curing accelerators, antistatic agents, conductivity imparting agents, stress relaxation agents, release agents, crystallization accelerators, hydrolysis inhibitors, lubricants, impact imparting agents, sliding property improvers, compatibilizers, nucleating agents, reinforcing agents, flow adjusters, dyes, sensitizers, colorants, anti-settling agents, anti-sagging agents, fillers, defoamers, light diffusing fine particles, rust inhibitors, antibacterial agents, anti-fungal agents, anti-fouling agents, conductive polymers, and the like.

[0028] [Extruder] The extruder of this embodiment can be of any form as long as it can heat the raw material to be pyrolyzed to a temperature of at least 300°C or higher, and can depolymerize at least a part of the raw material components into recycled monomers by pyrolysis. The pyrolysis temperature is preferably 300 to 500°C, more preferably 350 to 450°C, in order to increase the recovery rate of the methyl methacrylate-containing composition obtained by pyrolysis. Pyrolysis in an extruder is a continuous process, and is superior to the kettle method and fluidized bed method in terms of stabilization of the depolymerization process and ease of maintenance due to the stabilized thermal history. In addition, the rotary kiln method, which is the same continuous process, only performs pyrolysis by a heat source, but when an extruder is used, the depolymerization is promoted by the heat source and screw shear, making it possible to achieve more efficient chemical recycling. Furthermore, there is also the advantage that a temperature gradient can be provided between the raw material inlet and the outlet to prevent the decomposition gas from flowing back into the hopper.

[0029] After extrusion, a configuration in which residual components including undecomposed components such as inorganic components discharged from the outlet of the pyrolysis section of the extruder are separated into a storage tank, and the decomposition gas containing recycled methyl methacrylate generated by pyrolysis is separated into a recovery tank as a liquid component by cooling is preferable because this not only facilitates the recovery of the methyl methacrylate-containing composition but also facilitates the recycling of the inorganic components.

[0030] As a method for recycling inorganic components, any form can be used as long as the temperature is high enough to volatilize all organic components and calcinate the inorganic components by heating the storage tank or another tank to which the residual components, including undecomposed components such as inorganic components, are transferred to the storage tank.

[0031] When the object to be pyrolyzed is derived from artificial marble, silica or aluminum hydroxide is used as an inorganic filler, and in the former case it can be recycled as silica, and in the latter case it can be recycled as aluminum oxide through the firing process.

[0032] 1 is a schematic diagram showing the recovery process of a methyl methacrylate-containing composition according to the present embodiment, in which the arrows indicate the flow of the recycling process.

[0033] [Methacrylic resin composition using recycled methyl methacrylate-containing composition] In order to obtain a methacrylic resin composition from a recycled methyl methacrylate-containing composition, the component containing recycled methyl methacrylate separated in a recovery tank may be used for polymerization as is, or may be used for polymerization after increasing the purity through a process such as distillation or evaporation.

[0034] The polymerization method is not particularly limited, and it is preferable to use solution polymerization, bulk polymerization, suspension polymerization, emulsion polymerization, or the like, which are methods for producing methacrylic resin compositions that are available on the market. EXAMPLES

[0035] The present invention will be described in more detail with reference to the following examples and comparative examples, but the present invention is not limited to the following examples in any way.

[0036] [Methyl methacrylate copolymer (A) containing crosslinked portions] A-1: Methyl methacrylate copolymer containing a cross-linking portion contained in artificial marble containing aluminum hydroxide currently available on the market (the artificial marble in question is composed of A-1 and C-1 in a weight ratio of 45:55) A-2: Methyl methacrylate copolymer containing a cross-linking portion contained in artificial marble containing aluminum hydroxide that is available on the market (the artificial marble in question is composed of A-2 and C-1 in a weight ratio of 60:40) A-3: Methyl methacrylate copolymer containing a cross-linking portion contained in artificial marble containing silica currently available on the market (the artificial marble in question is composed of A-3 and C-2 in a weight ratio of 45:55) [Non-crosslinked methyl methacrylate copolymer (B)] B-1: Asahi Kasei Corporation, methacrylic resin "Delpet 80N" (weight average molecular weight 102,500), pellet form B-2: Asahi Kasei Corporation, methacrylic resin "Delpet 80NB" (weight average molecular weight 182,000), pellet form B-3: Asahi Kasei Corporation, methacrylic resin "Delpowder 80N" (weight average molecular weight 102,500), beads [Inorganic filler] The following inorganic fillers are contained in artificial marble on the market: C-1: Aluminum hydroxide C-2: Silica [Spreader] D-1: MORESCO liquid paraffin "Moresco White P-260"

[0037] [Weight average molecular weight] The weight average molecular weight of the non-crosslinked methyl methacrylate copolymer (B) was measured using the following device and under the following conditions. Measurement device: gel permeation chromatography (HLC-8320GPC) manufactured by Tosoh Corporation. Column: one TSKguardcolumn SuperH-H, two TSKgel SuperHM-M, and one TSKgel SuperH2500 were used, connected in series in this order. In this column, high molecular weight compounds elute early, while low molecular weight compounds elute late. Detector: RI (differential refractometer) detector Detection sensitivity: 3.0mV / min Column temperature: 40℃ Sample: 0.02 g of methacrylic resin in 20 mL of tetrahydrofuran Injection volume: 10μL Developing solvent: tetrahydrofuran, flow rate: 0.6 mL / min 2,6-di-t-butyl-4-methylphenol (BHT) was added at 0.1 g / L as an internal standard. As standard samples for the calibration curve, the following ten types of polymethyl methacrylate (PMMA Calibration Kit MM-10, manufactured by Polymer Laboratories) with different molecular weights and known monodisperse peak top molecular weights were used. Peak top molecular weight (Mp) Standard sample 1 1,916,000 Standard sample 2 625,500 Standard sample 3 298,900 Standard sample 4 138,600 Standard sample 5 60,150 Standard sample 6 27,600 Standard sample 7 10,290 Standard sample 8 5,000 Standard sample 9 2,810 Standard material 10 850 Under the above conditions, the RI detection intensity was measured versus the elution time of the methacrylic resin. The weight average molecular weight (Mw) of the methacrylic resin was determined based on the area in the GPC elution curve and a calibration curve of a third-order approximation equation.

[0038] [Recovery rate of methyl methacrylate-containing composition] The recovery rate of the component containing the recovered recycled methyl methacrylate, i.e., the methyl methacrylate-containing composition, was calculated from the following formula. Recovery rate (%) = weight of recovered methyl methacrylate-containing composition / weight of composition (1) excluding inorganic components

[0039] [Recycled methyl methacrylate yield] The yield (purity) of recycled methyl methacrylate in the recovered methyl methacrylate-containing composition was investigated using a gas chromatograph mass spectrometer. Equipment: Agilent7890B / 5977B Column: HP-5MS (L 30 m, I.D 0.250 mm, Film 0.25 μm) Carrier: Helium Detector: MSD Ionization method: EI (electron ionization) Oven temperature: 40℃(5min hold)→20℃ / min→320℃(10min hold) Inlet temperature: 320℃ Mass range: m / z 10-800

[0040] Example 1 <Preparation of composition (1)> Artificial marble containing a cross-linked methyl methacrylate copolymer (A-1) and an inorganic filler (C-1) was crushed to obtain a crushed product with a maximum length of 10 mm. The crushed product and a non-cross-linked methyl methacrylate copolymer (B-1) were uniformly dry-blended using a blender to prepare a composition (1). The weight ratio of the methyl methacrylate copolymer (A-1) to the non-cross-linked methyl methacrylate copolymer (B-1) was 50:50, and the inorganic filler (C-1) was 61 parts by weight per 100 parts by weight of the total of the methyl methacrylate copolymer (A-1) and the non-cross-linked methyl methacrylate copolymer (B-1).

[0041] <Pyrolysis> Composition (1) was fed into the raw material inlet of a commercially available twin-screw extruder, the flow path of which was filled with nitrogen gas as an inert gas. The temperature below the inlet was adjusted to 250°C, and the raw material was passed through a thermoplastic zone and a thermal decomposition zone adjusted to 450°C, where it was thermally decomposed at a feed rate of 40 kg / h. After extrusion, the residual components including undecomposed components such as inorganic components discharged from the outlet of the thermal decomposition section of the extruder were separated into a storage tank, and the gas containing recycled methyl methacrylate generated by thermal decomposition was separated into a recovery tank as a liquid component by cooling. The recovery rate was 92%, and the yield was 92%. Table 1 shows the recovery rate and yield.

[0042] (Examples 2 to 9) Preparation and pyrolysis of composition (1) were carried out in the same manner as in Example 1, except that the types and dry blend ratios of the methyl methacrylate copolymer (A) containing a crosslinked portion, the inorganic filler (C) and the non-crosslinked methyl methacrylate copolymer (B) were changed as shown in Table 1. Table 1 shows the recovery rate and yield.

[0043] (Examples 10 to 11) The composition (1) was prepared and pyrolyzed in the same manner as in Example 2, except that the spreading agent (D) was added per 100 parts by weight of the total of the methyl methacrylate copolymer (A-1) containing a crosslinked portion and the inorganic filler (C-1) during dry blending. The recovery rate and yield are shown in Table 1.

[0044] Example 12 Composition (1) was subjected to pyrolysis in the same manner as in Example 1, except that dry blending was not carried out in the preparation of composition (1).

[0045] (Example 13) Composition (1) was subjected to pyrolysis in the same manner as in Example 9, except that dry blending was not carried out in the preparation of composition (1).

[0046] Comparative Example 1 Except for changing the dry blend ratio of the methyl methacrylate copolymer (A-1) containing a crosslinked portion, the inorganic filler (C-1) and the non-crosslinked methyl methacrylate copolymer (B-1), the composition (1) was prepared and pyrolyzed in the same manner as in Example 1. The raw materials could not be extruded stably, and pyrolysis was not possible.

[0047] Comparative Example 2 Except for changing the dry blend ratio of the methyl methacrylate copolymer (A-2) containing a crosslinked portion, the inorganic filler (C-1) and the non-crosslinked methyl methacrylate copolymer (B-1), the composition (1) was prepared and pyrolyzed in the same manner as in Example 5. The raw materials could not be extruded stably, and pyrolysis was not possible.

[0048] [Table 1]

[0049] In Examples 1 and 9, in which dry blending was performed, the recovery rate and yield were better than in Examples 12 and 13, in which dry blending was not performed. [Explanation of symbols]

[0050] 1: Raw material input port 2: Pyrolysis device (extruder) 2a: Plasticization zone 2b: Pyrolysis zone 3: Methyl methacrylate-containing composition recovery section 3a: Cooling section 3b: Recovery tank 4: Storage tank [Industrial Applicability]

[0051] According to the method for recovering a methyl methacrylate-containing composition of the present invention, a methyl methacrylate-containing composition can be efficiently recovered by chemical recycling from a crosslinked methyl methacrylate copolymer containing an inorganic filler.

Claims

1. A method for recovering a methyl methacrylate-containing composition, comprising pyrolyzing a composition (1) in an extruder to obtain a methyl methacrylate-containing composition, the composition comprising a methyl methacrylate copolymer (A) containing a crosslinked portion and a non-crosslinked methyl methacrylate copolymer (B) in a weight ratio of A:B=95:5 to 5:95, the composition comprises 5 to 80 parts by weight of an inorganic filler per 100 parts by weight of the total of the methyl methacrylate copolymer (A) containing a crosslinked portion and the non-crosslinked methyl methacrylate copolymer (B), the methyl methacrylate copolymer (A) containing a crosslinked portion is pulverized together with the inorganic filler (property 1), and the non-crosslinked methyl methacrylate copolymer (B) is at least pulverized, in the form of a spherical powder or in the form of a pellet (property 2), and the (property 1) and (property 2) are mixed by dry blending.

2. The method for recovering a methyl methacrylate-containing composition according to claim 1, wherein the non-crosslinked methyl methacrylate copolymer (B) contains at least a component having a weight average molecular weight of 50,000 or more and less than 300,000.

3. The method for recovering a methyl methacrylate-containing composition according to claim 1, further comprising the step of: containing 0.01 to 10% by weight of a spreading agent relative to a total of 100% by weight of the methyl methacrylate copolymer (A) containing the crosslinked portion and the inorganic filler.

4. 2. The method for recovering a methyl methacrylate-containing composition according to claim 1, wherein the inorganic filler comprises aluminum hydroxide or silica.

5. The method for recovering a methyl methacrylate-containing composition according to claim 1, wherein a residual component containing an undecomposed component discharged from an outlet of the pyrolysis section of the extruder is separated into a storage tank, and a gas containing recycled methyl methacrylate generated by pyrolysis is separated into a liquid component by cooling into a recovery tank.

6. 6. The method for recovering a methyl methacrylate-containing composition according to claim 5, wherein the inorganic component contained in the residual component according to claim 5 is an aluminum compound, and the residual component is fired to obtain an aluminum oxide-containing composition from which organic components have been removed.

7. The method for recovering a methyl methacrylate-containing composition according to claim 5, wherein the inorganic component contained in the residual component according to claim 5 is a silicon compound, and the residual component is fired to obtain silica from which organic components have been removed.

8. The method for recovering a methyl methacrylate-containing composition according to claim 1, wherein the composition (1) is made of waste artificial marble.

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