Methods for manufacturing acrylic resins, acrylic resin films, and acrylic resin molded articles

Abstract

A method for manufacturing an acrylic resin, an acrylic resin film, and an acrylic resin molded article. The method for manufacturing an acrylic resin molded article includes a step of melt-molding an acrylic resin using an extruder. The acrylic resin comprises methyl methacrylate units, and its main chain comprises one or more ring structures selected from the group consisting of glutarimide rings, lactone rings, maleic anhydride rings, glutaric anhydride rings, and maleimide rings. When the content of methyl methacrylate dimer in the acrylic resin and the content of methyl methacrylate dimer in the acrylic resin molded article are set as A [weight ppm] and B [weight ppm] respectively, the reduction rate of methyl methacrylate dimer calculated by the formula: [(A-B) / A]×100 is 50% or more.

Description

Technical Field

[0001] This invention relates to methods for manufacturing acrylic resins, acrylic resin films, and acrylic resin molded articles. Background Technology

[0002] Acrylic resins have excellent transparency, color, appearance, heat resistance and processability, and are therefore used in optical films such as polarizer protective films and phase difference films.

[0003] Patent Document 1 describes a method for manufacturing a methacrylic acid copolymer, which includes the following steps: continuously supplying a raw material liquid into a trough reactor, carrying out bulk polymerization in the trough reactor to obtain a reaction product, and continuously extracting the reaction product from the trough reactor to remove volatile components from the reaction product.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: International Publication No. 2019 / 093385 Summary of the Invention

[0007] The problem the invention aims to solve

[0008] However, in recent years, with the improvement of optical film performance, there is a growing demand for higher quality optical films. On the other hand, when forming films of the methacrylic acid copolymers described in Patent Document 1 using the melt extrusion film-forming method, the casting rollers are sometimes contaminated. It can be inferred that this is because when manufacturing methacrylic acid copolymers through bulk polymerization, low molecular weight components such as methyl methacrylate dimers are generated, and these low molecular weight components will leach out during film formation.

[0009] The purpose of this invention is to provide a method for manufacturing acrylic resins, acrylic resin films, and acrylic resin molded articles with excellent resistance to roller contamination and heat resistance during film making.

[0010] Solution for solving the problem

[0011] (1) A method for manufacturing an acrylic resin molded body, the method comprising a step of melt molding an acrylic resin using an extruder, the acrylic resin comprising methyl methacrylate units, and the main chain comprising one or more ring structures selected from the group consisting of glutarimide ring, lactone ring, maleic anhydride ring, glutaric anhydride ring and maleimide ring, wherein when the content of methyl methacrylate dimer in the aforementioned acrylic resin and the content of methyl methacrylate dimer in the aforementioned acrylic resin molded body are respectively set as A [weight ppm] and B [weight ppm], the reduction rate of methyl methacrylate dimer calculated by formula: [(AB) / A]×100 is 50% or more.

[0012] (2) A method for manufacturing an acrylic resin molded body, the method comprising a step of melting and molding an acrylic resin using an extruder, wherein the acrylic resin contains methyl methacrylate units and has a glass transition temperature of 120°C or higher, and when the content of methyl methacrylate dimer in the aforementioned acrylic resin and the content of methyl methacrylate dimer in the aforementioned acrylic resin molded body are set as A [weight ppm] and B [weight ppm] respectively, the reduction rate of methyl methacrylate dimer calculated by formula: [(AB) / A]×100 is 50% or higher.

[0013] (3) The method for manufacturing an acrylic resin molded article according to (1) or (2), wherein the aforementioned acrylic resin molded article is granules or film.

[0014] (4) The method for manufacturing an acrylic resin molded article according to any one of (1) to (3), wherein the molecular weight dispersion (Mw / Mn) of the acrylic resin is 1.60 or more.

[0015] (5) The method for manufacturing an acrylic resin molded article according to any one of (1) to (4), wherein the content of methyl methacrylate dimer in the aforementioned acrylic resin molded article is less than 200 ppm by weight.

[0016] (6) The method for manufacturing an acrylic resin molded body according to any one of (1) to (5), wherein a 2cm square test piece cut from a 160μm thick film formed by molding the aforementioned acrylic resin molded body is placed in a glass petri dish with a diameter of 4cm and a height of 1cm, and the aforementioned glass petri dish is covered with a glass plate covered with aluminum foil, and heated at 285°C for 1 hour, wherein the relative fluorescence intensity of the volatiles transferred to the surface of the aforementioned aluminum foil is less than 2000RFU.

[0017] (7) The method for manufacturing an acrylic resin molded article according to any one of (1) to (6) further includes: a step of polymerizing methyl methacrylate in a solvent or dispersion medium to obtain a polymer; and a step of reacting the aforementioned polymer to obtain the aforementioned acrylic resin.

[0018] (8) The method for manufacturing an acrylic resin molded body according to (7), wherein the aforementioned methyl methacrylate is polymerized by solution polymerization, suspension polymerization or emulsion polymerization.

[0019] (9) An acrylic resin comprising methyl methacrylate units and having a main chain comprising one or more ring structures selected from the group consisting of glutarimide ring, lactone ring, maleic anhydride ring, glutaric anhydride ring and maleimide ring, wherein the content of methyl methacrylate dimer in the acrylic resin is less than 200 ppm by weight.

[0020] (10) According to the acrylic resin of (9), a 2cm square test piece cut from a 160μm thick film formed by molding the acrylic resin is placed in a glass petri dish with a diameter of 4cm and a height of 1cm. The glass petri dish is covered with a glass plate covered with aluminum foil, and heated at 285°C for 1 hour. The relative fluorescence intensity of the volatiles transferred to the surface of the aluminum foil is less than 2000RFU.

[0021] (11) The acrylic resin according to (9) or (10) has a molecular weight dispersion (Mw / Mn) of 1.60 or more.

[0022] (12) An acrylic resin film comprising a resin comprising methyl methacrylate units and a main chain comprising one or more ring structures selected from the group consisting of glutarimide ring, lactone ring, maleic anhydride ring, glutaric anhydride ring and maleimide ring, wherein the content of methyl methacrylate dimer in the acrylic resin film is less than 200 ppm by weight.

[0023] (13) The acrylic resin film according to (12) has an internal haze of less than 0.30%.

[0024] (14) The acrylic resin film according to (12) or (13) is a polarizer protective film.

[0025] (15) An acrylic resin comprising methyl methacrylate units, wherein the glass transition temperature of the acrylic resin is above 120°C and the content of methyl methacrylate dimer is less than 200 ppm by weight.

[0026] (16) An acrylic resin film comprising a resin, the resin comprising methyl methacrylate units and having a glass transition temperature of 120°C or higher, wherein the content of methyl methacrylate dimer in the acrylic resin film is less than 200 ppm by weight.

[0027] (17) The acrylic resin film according to (16) has a water contact angle of less than 70° at 23°C.

[0028] The effects of the invention

[0029] According to the present invention, a method for manufacturing acrylic resins, acrylic resin films, and acrylic resin molded articles with excellent resistance to roller contamination and heat resistance during film formation is provided. Detailed Implementation

[0030] The embodiments of the present invention will be described below.

[0031] (The first method using acrylic resins)

[0032] The acrylic resin of this embodiment comprises methyl methacrylate units, and the main chain comprises one or more ring structures selected from the group consisting of glutarimide rings, lactone rings, maleic anhydride rings, glutaric anhydride rings, and maleimide rings. Therefore, the acrylic resin of this embodiment exhibits higher heat resistance.

[0033] In this specification and claims, acrylic resins refer to resins containing methyl methacrylate units and optionally structural units other than methyl methacrylate units. There are no particular limitations on structural units other than methyl methacrylate units; examples include alkyl (meth)acrylate units other than methyl methacrylate units; aromatic vinyl units such as styrene units and methylstyrene units; (meth)acrylonitrile units; and structural units containing ring structures, described later.

[0034] The acrylic resin of this embodiment contains less than 200 ppm by weight of methyl methacrylate dimer, preferably less than 150 ppm by weight. Because the acrylic resin of this embodiment contains less than 200 ppm by weight of methyl methacrylate dimer, the acrylic resin of this embodiment exhibits higher resistance to roller fouling and heat resistance during film formation. It can be inferred that the reason for the increased resistance to roller fouling during film formation of the acrylic resin of this embodiment is that even when the acrylic resin of this embodiment is formed by melt extrusion film formation, the amount of methyl methacrylate dimer exuded is reduced.

[0035] It should be noted that when synthesizing the acrylic resin of this embodiment, in order to suppress the formation of methyl methacrylate dimers, it is necessary to reduce the frequency of contact between free radicals during the polymerization of methyl methacrylate. In polymerization methods using solvents or dispersion media, such as suspension polymerization, emulsion polymerization, and solution polymerization, the monomer concentration in the polymerization system is low; therefore, there is a tendency for the frequency of contact between free radicals to decrease, and the formation of dimers to be suppressed. Furthermore, in aqueous polymerization methods using dispersants or surfactants, such as suspension polymerization and emulsion polymerization, free radicals are generated in the aqueous phase or at the interface with the aqueous phase, and monomers are present in the particles or droplets; therefore, there is a tendency for the frequency of contact between free radicals to further decrease, and the formation of dimers to be suppressed.

[0036] It should be noted that when synthesizing the acrylic resin of this embodiment, in order to suppress the formation of methyl methacrylate dimers, from the viewpoint of suppressing the rapid generation of free radicals, the polymerization temperature needs to be controlled at a low level during the polymerization of methyl methacrylate. Here, in polymerization methods using solvents or dispersion media, such as suspension polymerization, emulsion polymerization, and solution polymerization, the viscosity of the polymerization system increases less due to the absorption of polymerization heat by the solvent or dispersion media; therefore, it is not necessary to increase the polymerization temperature to maintain the polymerization rate. On the other hand, in polymerization methods without solvents or dispersion media, such as bulk polymerization, the monomer concentration in the polymerization system is high; therefore, there is a tendency for the viscosity to increase rapidly if polymerization proceeds, hindering the diffusion of free radicals. Therefore, in order to maintain the polymerization rate, it is necessary to increase the polymerization temperature. It can be inferred that these phenomena will affect the formation of methyl methacrylate dimers. Furthermore, in continuous bulk polymerization, unreacted monomers are heated and recovered after polymer synthesis; therefore, this is a major reason for the increased formation of methyl methacrylate dimers.

[0037] There are no particular limitations on the method for polymerizing methyl methacrylate, and examples include solution polymerization, suspension polymerization, and emulsion polymerization. Among these, suspension polymerization and emulsion polymerization are preferred because: by using water with high heat removal efficiency, the polymerization temperature can be maintained at a low level, and by having monomers in the particles or droplets, the frequency of contact between free radicals can be suppressed.

[0038] A 2cm square test piece, cut from a 160μm thick film formed from the acrylic resin of this embodiment, was placed in a glass petri dish with a diameter of 4cm and a height of 1cm. With the glass petri dish covered entirely by an aluminum foil plate, it was heated at 285°C for 1 hour. The relative fluorescence intensity of the volatiles transferred to the aluminum foil surface was preferably less than 2000 RFU, more preferably less than 1500 RFU. If the relative fluorescence intensity of the volatiles was less than 2000 RFU, the acrylic resin of this embodiment exhibited higher resistance to roller contamination during film formation. Furthermore, the relative fluorescence intensity of the volatiles was, for example, 500 RFU or higher.

[0039] The molecular weight dispersion (Mw / Mn) of the acrylic resin in this embodiment is preferably 1.60 or more, more preferably 1.70 or more, even more preferably 1.80 or more, and even more preferably more than 1.80. If the molecular weight dispersion of the acrylic resin in this embodiment is 1.60 or more, the acrylic resin in this embodiment exhibits higher resistance to roller contamination during film formation. Furthermore, the molecular weight dispersion (Mw / Mn) of the acrylic resin in this embodiment is, for example, 2.00 or less. Additionally, the weight-average molecular weight (Mw) of the acrylic resin in this embodiment is not particularly limited, but is, for example, 50,000 or more and 200,000 or less.

[0040] The content of methyl methacrylate dimer in the acrylic resin of this embodiment is set as D1 [weight ppm], and the shear rate is 24s. -1 When the content of methyl methacrylate dimer after heating the acrylic resin of this embodiment for 1 hour at a temperature where the melt viscosity reaches 7000 Poise is set as D2 [wt ppm], it is preferable to satisfy the formula: D2-D1≤1000, more preferably satisfying the formula: D2-D1≤500. If (D2-D1) is 1000 or less, the acrylic resin of this embodiment exhibits higher resistance to roller contamination during film formation. Furthermore, (D2-D1) is, for example, 100 or more.

[0041] The glass transition temperature of the acrylic resin in this embodiment is preferably 120°C or higher, more preferably above 120°C, even more preferably 121°C or higher, and even more preferably 122°C or higher. When the glass transition temperature of the acrylic resin in this embodiment is 120°C or higher, the heat resistance of the acrylic resin film is increased. Furthermore, the glass transition temperature of the acrylic resin in this embodiment is preferably 160°C or lower, more preferably 150°C or lower, and even more preferably 145°C or lower.

[0042] The following describes acrylic resins whose main chain contains a glutarimide ring or a lactone ring.

[0043] Acrylic resins whose main chain contains a glutarimide ring, for example, contain the structural unit shown in formula (1) and a methyl methacrylate unit.

[0044]

[0045] (where R) 1 and R 2 Each is independently an alkyl group having 1 or more but less than 8 hydrogen atoms, R 3 (It can be a hydrogen atom, an alkyl group having 1 or more but less than 18 carbon atoms, or a cycloalkyl group having 3 or more but less than 12 carbon atoms.)

[0046] Acrylic resins comprising the structural unit shown in Formula (1) and the methyl methacrylate unit can be manufactured using known methods. Hereinafter, an example of a method for manufacturing an acrylic resin comprising the structural unit shown in Formula (1) and the methyl methacrylate unit will be described.

[0047] First, methyl methacrylate is homopolymerized to obtain polymethyl methacrylate. Next, using a twin-screw extruder with a die at the outlet, the polymethyl methacrylate is melted, imidized, and extruded as strands from the die. Then, the strands are cooled in a water bath and granulated using a granulator to obtain imidized polymethyl methacrylate. Next, using a twin-screw extruder with a die at the outlet, the imidized polymethyl methacrylate is melted, esterified, and extruded as strands from the die. Then, the strands are cooled in a water bath and granulated using a granulator to obtain an acrylic resin containing the structural unit shown in formula (1) and a methyl methacrylate unit.

[0048] The imidizing agent used for imidizing polymethyl methacrylate is not particularly limited, and examples include ammonia and the primary amine shown in formula (2) below. Among them, ammonia and monomethylamine are preferred. In this case, the imidization rate of polymethyl methacrylate is not particularly limited, and can be appropriately set according to the glass transition temperature of acrylic resin.

[0049] R 3 NH2 (2)

[0050] (where R) 3 Synonymous with equation (1).

[0051] Examples of esterifying agents used in the esterification of imidized polymethyl methacrylate include: dimethyl carbonate, 2,2-dimethoxypropane, dimethyl sulfoxide, triethyl orthoformate, trimethyl orthoacetate, trimethyl orthoformate, diphenyl carbonate, dimethyl sulfate, methyl toluenesulfonate, methyl trifluoromethyl sulfonate, methyl acetate, methanol, ethanol, methyl isocyanate, p-chlorophenyl isocyanate, dimethylcarbodiimide, dimethyl tert-butylchlorosilane, isopropylene acetate, dimethylurea, tetramethylammonium hydroxide, dimethyldiethoxysilane, tetra-n-butoxysilane, dimethyl (trimethylsilane) phosphite, trimethyl phosphite, trimethyl phosphate, tricresyl phosphate, diazomethane, ethylene oxide, propylene oxide, cyclohexane oxide, 2-ethylhexyl glycidyl ether, phenyl glycidyl ether, and benzyl glycidyl ether. Dimethyl carbonate is preferred.

[0052] Acrylic resins whose main chain contains a lactone ring are obtained, for example, by copolymerizing the monomer shown in formula (3) with methyl methacrylate and then subjecting it to heat treatment to form a lactone ring.

[0053]

[0054] (where R) 4 and R 5 Each is independently an alkyl group having 1 or more hydrogen atoms and 20 or fewer carbon atoms.

[0055] Examples of monomers represented by formula (3) include methyl 2-(hydroxymethyl)acrylate, ethyl 2-(hydroxymethyl)acrylate, isopropyl 2-(hydroxymethyl)acrylate, n-butyl 2-(hydroxymethyl)acrylate, and tert-butyl 2-(hydroxymethyl)acrylate, and two or more may be used in combination. Among these, methyl 2-(hydroxymethyl)acrylate and ethyl 2-(hydroxymethyl)acrylate are preferred, and methyl 2-(hydroxymethyl)acrylate is particularly preferred.

[0056] As a method for copolymerizing the monomer shown in formula (3) with methyl methacrylate, there are no particular limitations as long as the content of methyl methacrylate dimer in the acrylic resin is less than 200 ppm by weight. For example, suspension polymerization and emulsion polymerization can be used.

[0057] It should be noted that, as an acrylic resin whose main chain contains ring structures other than glutarimide rings and lactone rings, a known acrylic resin used in acrylic resin films can be used.

[0058] The content of structural units comprising one or more ring structures selected from the group consisting of glutarimide rings, lactone rings, maleic anhydride rings, glutaric anhydride rings, and maleimide rings in the acrylic resin is preferably 1% by weight or more and 70% by weight or less, more preferably 2% by weight or more and 50% by weight or less, and even more preferably 4% by weight or more and 30% by weight or less. If the content of structural units comprising one or more ring structures selected from the group consisting of glutarimide rings, lactone rings, maleic anhydride rings, glutaric anhydride rings, and maleimide rings in the acrylic resin is 2% by weight or more, the heat resistance of the acrylic resin film is increased; if it is 50% by weight or less, the processability of the acrylic resin film is increased.

[0059] (The first method for acrylic resin films)

[0060] The acrylic resin film of this embodiment comprises a resin containing methyl methacrylate units, and the main chain comprises one or more ring structures selected from the group consisting of glutarimide rings, lactone rings, maleic anhydride rings, glutaric anhydride rings, and maleimide rings. Therefore, the acrylic resin film of this embodiment exhibits higher heat resistance.

[0061] The acrylic resin film of this embodiment contains less than 200 ppm by weight of methyl methacrylate dimer, preferably less than 100 ppm by weight. Because the acrylic resin film of this embodiment contains less than 200 ppm by weight of methyl methacrylate dimer, it exhibits higher resistance to roller contamination and heat resistance during film formation.

[0062] The internal haze of the acrylic resin film in this embodiment is preferably 0.30% or less, more preferably 0.25% or less. When the internal haze of the acrylic resin film in this embodiment is 0.30% or less, the optical properties of the acrylic resin film in this embodiment are improved. It should be noted that the internal haze of the acrylic resin film in this embodiment is, for example, 0.10% or more. In addition, the haze of the acrylic resin film in this embodiment is not particularly limited, for example, it is 0.10% or more and 0.35% or less.

[0063] The acrylic resin film of this embodiment preferably has a contact angle with water of less than 70° at 23°C, more preferably less than 69°, and even more preferably less than 68°. If the acrylic resin film of this embodiment has a contact angle with water of less than 70° at 23°C, good coatability can be obtained when coating the acrylic resin film of this embodiment with an easy-to-adhere agent or other aqueous coating agent. Furthermore, the acrylic resin film of this embodiment tends to exhibit improved resistance to roller contamination during film formation. This is presumably because the surface of the acrylic resin film, which contains acrylic resin manufactured by aqueous polymerization, tends to be hydrophilic, making it easily compatible with aqueous coating agents. Additionally, the hydrophobic methyl methacrylate dimer becomes less likely to migrate to the hydrophilic surface.

[0064] The number of foreign objects present in a 20cm square area of ​​the acrylic resin film of this embodiment is preferably less than 5, more preferably less than 2. If the number of foreign objects present in a 20cm square area of ​​the acrylic resin film of this embodiment is less than 5, the optical properties of the acrylic resin film of this embodiment are improved. Here, the major diameter of the foreign object is 30μm or more.

[0065] The glass transition temperature of the resin contained in the acrylic resin film of this embodiment is preferably 120°C or higher, more preferably exceeding 120°C, even more preferably 121°C or higher, and even more preferably 122°C or higher. When the glass transition temperature of the resin contained in the acrylic resin film of this embodiment is 120°C or higher, the heat resistance of the acrylic resin film of this embodiment is higher. Furthermore, the glass transition temperature of the resin contained in the acrylic resin of this embodiment is, for example, 130°C or lower.

[0066] The use of the acrylic resin film in this embodiment is not particularly limited; for example, optical films such as polarizer protective films and phase difference films can be cited.

[0067] (Method for manufacturing acrylic resin films)

[0068] The acrylic resin film of this embodiment can be manufactured using known methods. Hereinafter, an example of a method for manufacturing the acrylic resin film of this embodiment will be described.

[0069] First, using an extruder equipped with a T-die at the outlet, the acrylic resin of this embodiment is melted and extruded as a sheet from the T-die. The sheet is then cooled by cooling rollers to obtain a roll of film. Next, the roll of film is biaxially stretched to obtain the acrylic resin film of this embodiment. The biaxial stretching can be simultaneous or sequential.

[0070] When the glass transition temperature of the acrylic resin in this embodiment is set to Tg, the temperature for biaxial stretching of the original roll film is preferably (Tg+5)°C or higher and (Tg+20)°C or lower, more preferably (Tg+6)°C or higher and (Tg+18)°C or lower, and even more preferably (Tg+7)°C or higher and (Tg+15)°C or lower. Furthermore, the aspect ratio for biaxial stretching of the original roll film is not particularly limited, for example, it is 2 times or higher and 10 times or lower. The stretching speed for biaxial stretching of the original roll film is not particularly limited, for example, it is 1.1 times / minute or higher and 100 times / minute or lower. When performing successive biaxial stretching of the original roll film, the stretching speed of the first stage and the stretching speed of the second stage can be the same or different. It should be noted that in successive biaxial stretching, typically, the first stage stretching is in the length direction (MD direction), and the second stage stretching is in the width direction (TD direction).

[0071] (Second method using acrylic resins)

[0072] The acrylic resin of this embodiment contains methyl methacrylate units and has a glass transition temperature of 120°C or higher. Therefore, the heat resistance of the acrylic resin film is improved.

[0073] The glass transition temperature of the acrylic resin in this embodiment is 120°C or higher, preferably higher than 120°C, more preferably 121°C or higher, and even more preferably 122°C or higher. Furthermore, the glass transition temperature of the acrylic resin in this embodiment is preferably 160°C or lower, more preferably 150°C or lower, and even more preferably 145°C or lower.

[0074] In this embodiment, the methyl methacrylate dimer content in the acrylic resin is less than 200 ppm by weight, preferably less than 180 ppm by weight, more preferably less than 160 ppm by weight, further preferably less than 150 ppm by weight, and even more preferably less than 100 ppm by weight. Because the methyl methacrylate dimer content in the acrylic resin of this embodiment is less than 200 ppm by weight, the acrylic resin of this embodiment exhibits higher resistance to roller contamination and heat resistance during film formation.

[0075] It should be noted that the acrylic resin in this embodiment can also serve as the first type of acrylic resin described above.

[0076] (Second method for acrylic resin films)

[0077] The acrylic resin film of this embodiment comprises a resin containing methyl methacrylate units and has a glass transition temperature of 120°C or higher. Therefore, the acrylic resin film of this embodiment exhibits higher heat resistance.

[0078] The acrylic resin film of this embodiment contains a resin with a glass transition temperature of 120°C or higher, preferably exceeding 120°C, more preferably 121°C or higher, and even more preferably 122°C or higher. It should be noted that the acrylic resin film of this embodiment contains a resin with a glass transition temperature preferably below 160°C, more preferably below 150°C, and even more preferably below 145°C.

[0079] The acrylic resin film of this embodiment contains less than 200 ppm by weight of methyl methacrylate dimer, preferably less than 150 ppm by weight. Because the acrylic resin film of this embodiment contains less than 200 ppm by weight of methyl methacrylate dimer, it exhibits higher resistance to roller contamination and heat resistance during film formation.

[0080] It should be noted that the acrylic resin film of this embodiment can also serve as the first type of acrylic resin film described above.

[0081] (Manufacturing method of acrylic resin molded articles)

[0082] The first aspect of the method for manufacturing an acrylic resin molded article according to this embodiment includes a step of melt molding an acrylic resin using an extruder. The acrylic resin comprises methyl methacrylate units, and its main chain includes one or more ring structures selected from the group consisting of glutarimide rings, lactone rings, maleic anhydride rings, glutaric anhydride rings, and maleimide rings. In this case, it is preferable to feed the acrylic resin to the extruder. When the molded article is in granule form, a raw material resin of the acrylic resin (e.g., a polymer described later) can be fed to the extruder to melt mold the acrylic resin, or an acrylic resin with a ring structure in its main chain (e.g., beads) can be fed to the extruder for melt molding.

[0083] The second aspect of the method for manufacturing an acrylic resin molded article according to this embodiment includes a step of melt molding an acrylic resin using an extruder, wherein the acrylic resin contains methyl methacrylate units and has a glass transition temperature of 120°C or higher.

[0084] If the content of methyl methacrylate dimer in the acrylic resin and the content of methyl methacrylate dimer in the acrylic resin molded body are set as A [weight ppm] and B [weight ppm], respectively, then the reduction rate of methyl methacrylate dimer calculated by the formula: [(AB) / A]×100 is 50% or more, preferably 60% or more, more preferably 75% or more, further preferably 80% or more, and even more preferably 90% or more. Since the reduction rate of methyl methacrylate dimer is 50% or more, the resistance of the acrylic resin molded body to roller contamination is increased.

[0085] As an acrylic resin molded body, there are no particular limitations; for example, granules and films can be included.

[0086] The molecular weight dispersion (Mw / Mn) of the acrylic resin is preferably 1.60 or higher, more preferably 1.70 or higher, even more preferably 1.80 or higher, and even more preferably greater than 1.80. If the molecular weight dispersion of the acrylic resin is 1.60 or higher, the acrylic resin molded article exhibits higher resistance to roller contamination during film formation. Furthermore, the molecular weight dispersion (Mw / Mn) of the acrylic resin is, for example, 2.00 or lower. Additionally, the weight-average molecular weight (Mw) of the acrylic resin is not particularly limited, but is, for example, 50,000 or higher and 200,000 or lower.

[0087] The content of methyl methacrylate dimer in the acrylic resin molded article is preferably less than 200 ppm by weight, more preferably less than 150 ppm by weight. When the content of methyl methacrylate dimer in the acrylic resin molded article is less than 200 ppm by weight, the acrylic resin molded article has higher resistance to roller contamination and heat resistance during film making.

[0088] A 2cm square test piece, cut from a 160μm thick film formed by molding an acrylic resin body, is placed in a glass petri dish with a diameter of 4cm and a height of 1cm. The petri dish is then covered with a glass plate entirely covered with aluminum foil and heated at 285°C for 1 hour. The relative fluorescence intensity of the volatiles transferred to the aluminum foil surface is preferably less than 2000 RFU, more preferably less than 1500 RFU. If the relative fluorescence intensity of the volatiles is less than 2000 RFU, the resistance of the acrylic resin body to roller contamination during film formation is increased. Alternatively, the relative fluorescence intensity of the volatiles is, for example, 500 RFU or higher.

[0089] The method for manufacturing the acrylic resin molded article of this embodiment may further include: a step of polymerizing methyl methacrylate in a solvent or dispersion medium to obtain a polymer; and a step of reacting the polymer to obtain the acrylic resin of this embodiment. As for the polymer, there is no particular limitation as long as it contains methyl methacrylate units; for example, polymethyl methacrylate can be listed.

[0090] The embodiments of the present invention have been described above, but the present invention is not limited to the above embodiments, and the above embodiments may be appropriately modified within the scope of the present invention.

[0091] Example

[0092] (Aggregation Conversion Rate)

[0093] The polymerization conversion rate [%) is determined by gravimetric method based on the ratio of the weight of the solid components of the polymerization liquid to the weight of the fed monomers. The polymerization liquid is then dried in an oven set at 150°C for 30 minutes to determine the weight of the solid components.

[0094] (Glass transition temperature Tg)

[0095] The glass transition temperature of the resin composition was determined using a differential scanning calorimetry (DSC) device (manufactured by Hitachi High-Tech Science). Specifically, firstly, the temperature was increased from 40°C to 160°C at a rate of 10°C / min under a nitrogen flow rate of 40 mL / min, cooled to 40°C, and then increased from 40°C to 160°C again at a rate of 10°C / min. Next, the glass transition temperature Tg (midpoint glass transition temperature) was read from the DSC curve measured during the second heating. Here, the midpoint glass transition temperature is the temperature at the intersection of the following straight line with the step-like change portion of the glass transition of the DSC curve. This straight line is a straight line equidistant from the baseline before the inflection point of the DSC curve towards the high-temperature side and the straight line after the inflection point of the DSC curve towards the low-temperature side.

[0096] (Content of methyl methacrylate (MMA) dimer)

[0097] The content of MMA dimers in acrylic resins or acrylic resin films was determined using a gas chromatograph GC2010 (manufactured by Shimadzu Corporation) and a liquid chromatography column RTX-1 (manufactured by RESTEK Corporation) with a film thickness of 5 μm, a length of 30 μm, and an inner diameter of 0.5 mm, under the following test conditions.

[0098] Sample to be tested: 1g of acrylic resin or acrylic resin film, 20g of dichloromethane

[0099] Temperature of the vaporization chamber: 200℃

[0100] Detector temperature: 270℃

[0101] Column oven temperature profile:

[0102] 1) Keep at 35℃ for 5 minutes.

[0103] 2) Heat to 70°C at a rate of 5°C / minute.

[0104] 3) Increase the temperature to 270℃ at a rate of 20℃ / minute and hold for 40 minutes.

[0105] Gas flow rates: Helium (30 ml / min), Air (400 ml / min), Hydrogen (40 ml / min)

[0106] It should be noted that the amount of MMA dimer is determined based on the area of ​​the peak detected at the retention time corresponding to dimethyl 1-hexene-2,5-dicarboxylate in the gas chromatogram, according to the pre-prepared standard curve of MMA.

[0107] (Reduction rate of methyl methacrylate (MMA) dimer)

[0108] If the content of methyl methacrylate dimer in acrylic resin and the content of methyl methacrylate dimer in acrylic resin molded body (film) are set as A [weight ppm] and B [weight ppm] respectively, the reduction rate of methyl methacrylate dimer [%] can be calculated by the formula: [(AB) / A]×100.

[0109] (Weight-average molecular weight (Mw) and molecular weight dispersion (Mw / Mn))

[0110] Using a high-speed GPC apparatus HLC-8420GPC (manufactured by Tosoh Corporation), the weight-average molecular weight (Mw) and molecular weight dispersion (Mw / Mn) of acrylic resins were calculated using the standard polystyrene conversion method. Specifically, the analysis was performed using a sample solution prepared by dissolving 15 mg of acrylic resin in 10 mL of tetrahydrofuran under the following conditions.

[0111] Detector: RI detector

[0112] Solvent: Tetrahydrofuran

[0113] Protective column: TSKguardcolumn SuperH-L

[0114] Analytical columns: TSKgel SuperH5000, TSKgel SuperH4000, TSKgel SuperH3000, TSKgelSuperH2000

[0115] Measurement temperature: 40℃

[0116] Standard material: Standard polystyrene (manufactured by Tosoh Corporation)

[0117] (Total transmittance)

[0118] The total transmittance of acrylic resin films was measured using a haze meter NDH2000 (manufactured by Nippon Denshoku Kogyo Co., Ltd.) in accordance with JIS7361-1.

[0119] (Haze)

[0120] The haze of acrylic resin films was measured using an NDH2000 haze meter (manufactured by Nippon Denshoku Kogyo Co., Ltd.) in accordance with JIS 7136:2000.

[0121] (Internal haze)

[0122] The internal haze of acrylic resin films was measured using an NDH2000 haze meter (manufactured by Nippon Denshoku Kogyo Co., Ltd.) according to JIS 7136:2000. Specifically, firstly, to eliminate the influence of surface scattering of the acrylic resin film, glycerin was dropped onto both the surface and back of the film, which was then held in place with a glass plate. The haze was measured with the interface between the film and the glass plate filled with glycerin. Next, the internal haze of the acrylic resin film was calculated by subtracting the previously measured haze from the glass plate haze.

[0123] (In-plane phase difference Re and thickness direction phase difference Rth)

[0124] After cutting 40mm × 40mm test pieces from an acrylic resin film, the in-plane phase difference Re was measured at a wavelength of 590nm and an incident angle of 0° using a KOBRA-WR phase difference measuring device (manufactured by Oji Measurement Co., Ltd.) under conditions of 23±2℃ and 50±5% humidity. Next, the thickness d of the test piece was measured using a digital indicator (manufactured by MITUTOYO Co., Ltd.), and the refractive index n was measured using a precision Abbe refractometer NAR-3T (manufactured by Atago Co., Ltd.). Then, based on the in-plane phase difference Re and the phase difference along the 40° tilt direction, the three-dimensional refractive indices nx, ny, and nz were calculated. Finally, the phase difference Rth in the thickness direction was calculated using the formula: Rth = |(nx + ny) / 2 - nz| × d.

[0125] (Containment percentage of structural units with glutarimide rings)

[0126] The properties of acrylic resins were determined using an Avance III nuclear magnetic resonance (NMR) system with a proton resonance frequency of 400 MHz (manufactured by BRUKER). 1 H-NMR spectrum. Next, based on the acrylic resin... 1 By analyzing the peak area ratio of the H-NMR spectra, the molar ratio of methyl methacrylate units to structural units containing glutarimide rings was determined. Then, a weight conversion was performed to calculate the content of structural units containing glutarimide rings. At this point, the molar ratio was calculated based on the peak areas of O-CH3 protons from methyl methacrylate units (around 3.5–3.8 ppm) and N-CH3 protons from structural units containing glutarimide rings (around 3.0–3.3 ppm).

[0127] (Containment percentage of structural units with lactone rings)

[0128] Using tetrahydrofuran as a good solvent and hexane as a poor solvent, the acrylic resin was reprecipitated and purified. After drying in a hot air oven at 75°C for 10 hours, the content of structural units containing lactone rings was determined according to the method described in Japanese Patent Application Publication No. 2021-42353

[0228] .

[0129] (Resistance to roller contamination)

[0130] Acrylic resin was supplied to a KZW15TWIN-45MG (manufactured by TECHNOVEL) co-rotating twin-screw extruder with a 15mm diameter T-die and an L / D ratio of 45. The acrylic resin film was continuously formed for 1 hour at a feeder speed of 65 rpm, a screw speed of 300 rpm, and an extrusion temperature of 270°C. During this time, the sheet discharged from the T-die was cooled and wound up via a casting roller set to 110°C to form a film with a thickness of 100 μm. It should be noted that before film formation, the surface of the casting roller was wiped with a nonwoven cloth impregnated with chloroform. After the acrylic resin film was formed, the contamination status of the casting roller surface was visually observed to evaluate the roller contamination resistance. The evaluation criteria for roller contamination resistance are as follows.

[0131] A: No white haze-like contamination was detected on the surface of the casting roller.

[0132] B: White haze-like contamination was confirmed on the surface of the casting roller.

[0133] (Relative fluorescence intensity of volatiles)

[0134] After cutting 2cm square test pieces from a 160μm thick acrylic resin film, they were placed in a 4cm diameter, 1cm high glass petri dish. Next, a 5cm square glass plate, entirely covered with aluminum foil, was placed over the petri dish and heated on a hot plate set to 285°C for 1 hour. After removing the glass plate, the relative fluorescence intensity of the volatiles transferred to the aluminum foil surface was measured using a CLEANOSPECTOR (manufactured by SITA). It should be noted that the CLEANOSPECTOR measures relative fluorescence intensity by irradiating the surface with UV light and detecting the fluorescence of organic matter, allowing for the quantification of the amount of organic matter transferred to the aluminum foil surface based on the intensity. Relative fluorescence intensity is expressed in RFU (Relative Fluorescence Units); a lower RFU value indicates a smaller amount of transferred organic matter. In addition, the metal surface cleanliness tester has a measurement range of 0~2,000 RFU.

[0135] (Changes in the content of methyl methacrylate dimer before and after retention (D2-D1))

[0136] Using a Capirograph 1D and a capillary die (manufactured by Toyo Seiki Co., Ltd.) with a length of 10 mm and an aperture of 1 mm, at a shearing speed of 24 s -1 Under the given conditions, the correlation curves representing the relationship between temperature and melt viscosity of acrylic resins were obtained. Then, the temperature T [°C] at which the melt viscosity of the acrylic resin reaches 7000 Poise was determined using interpolation or extrapolation.

[0137] Using a Capirograph 1D microscope and a capillary mold (manufactured by Toyo Seiki Co., Ltd.) with a length of 10 mm and an aperture of 1 mm, acrylic resin was allowed to remain in the barrel for 1 hour at T [°C]. The content of methyl methacrylate dimer in the discharged strand, D2 [wt ppm], was then determined using the analytical method described above. Similarly, the content of methyl methacrylate dimer in the acrylic resin before retention, D1 [wt ppm], was also determined, and the change in the content of methyl methacrylate dimer before and after retention (D2-D1) [wt ppm] was calculated.

[0138] (Water contact angle)

[0139] Using an SImage AUTO 100 automatic contact angle meter (manufactured by Excimer), the water contact angle of an acrylic resin film at 23°C was determined by the droplet method in AutoMode mode. The measurement position on the surface of the acrylic resin film was changed, and the contact angle relative to water was measured a total of 10 times, with the average value (n=10) used to calculate the result.

[0140] (Example 1)

[0141] (Manufacturing of acrylic resin A)

[0142] In a 4L glass reactor equipped with an H-type impeller stirrer, 150 parts by weight of deionized water, 0.20 parts by weight of tricalcium phosphate as a dispersant, 0.0075 parts by weight of sodium α-olefin sulfonate, and 0.30 parts by weight of sodium chloride were added. Then, under a nitrogen atmosphere, while stirring at 250 rpm, 100 parts by weight of methyl methacrylate, 0.289 parts by weight of n-octyl mercaptan as a chain transfer agent, and 0.074 parts by weight of dimethyl 2,2'-azobis(isobutyrate) V-601 (manufactured by Fujifilm and Koko Pure Chemical Industries Co., Ltd.) as a polymerization initiator were added to the reactor. The reactor temperature was then raised to 70°C to begin polymerization. Two hours after the start of polymerization, 0.10 parts by weight of tricalcium phosphate were added to the polymerization solution. At this point, four hours and twenty minutes after the start of polymerization, an exothermic peak associated with the gelation effect was observed. The temperature was raised to 95°C 7 hours after the start of polymerization. At this point, the polymerization conversion rate was 93%. Two hours after the reactor temperature reached 95°C, the reactor was cooled to room temperature, ending the polymerization and yielding a dispersion of acrylic resin. At this point, the polymerization conversion rate was 99%. The acrylic resin dispersion was then washed with 1 equivalent of hydrochloric acid (0.1 times the weight of the added monomer), followed by washing with water to remove the dispersant. The washed acrylic resin was then dehydrated and dried to obtain bead-like acrylic resin.

[0143] The temperature settings of each temperature control zone of a 40mm diameter, L / D=90 co-rotating twin-screw extruder with an outlet die were set to 250~280℃, and the screw speed was set to 85rpm. Beads of acrylic resin were melted and filled using a kneading block. Next, 1.8% by weight of monomethylamine (manufactured by Mitsubishi Gas Chemical Co., Ltd.) was injected through the nozzle relative to the acrylic resin to imidize it. The extruded strands were then cooled in a water bath and granulated using a granulator to obtain acrylic resin A granules. Acrylic resin A has a Mw of 101,300, an Mw / Mn ratio of 1.72, and contains 6% by weight of structural units containing glutarimide rings.

[0144] (Manufacturing of acrylic resin film A)

[0145] Acrylic resin A granules are fed into a KZW15TWIN-45MG (TECHNOVEL) co-rotating twin-screw extruder with a 15mm diameter T-die and an L / D ratio of 45. Film is formed by melt extrusion at an extrusion temperature of 260°C. The sheet exiting the T-die is cooled and wound up via a casting roller to obtain a roll of film with a width of 160mm and a thickness of 160μm. Next, 100mm × 100mm films are cut from the roll of film with both sides parallel to the extrusion direction. The films are then placed in a biaxial stretching device and simultaneously biaxially stretched at a stretching temperature of 142°C and a stretching speed of 100mm / min, with a stretching ratio of 2 times in both the parallel and perpendicular directions relative to the extrusion direction. The film is then removed and cooled at room temperature to obtain an acrylic resin film A with a thickness of 40μm.

[0146] (Example 2)

[0147] (Manufacturing of acrylic resin B)

[0148] In an 8L glass reactor equipped with a paddle mixer, 350 parts by weight of deionized water, 0.004 parts by weight of sodium hydroxide, and 0.2 parts by weight of sodium dioctyl sulfosuccinate were added. Under a nitrogen atmosphere, the reactor was stirred at 140 rpm while the temperature was raised to 60°C. Next, 0.1 parts by weight of tert-butyl hydroperoxide were added, followed by a mixed aqueous solution of disodium ethylenediaminetetraacetate (EDTA), 0.0055 parts by weight of ferrous sulfate heptahydrate, and 0.1 parts by weight of sodium formaldehyde sulfoxylate. Then, a monomer mixture comprising 80 parts by weight of methyl methacrylate, 20 parts by weight of ethyl 2-(hydroxymethyl)acrylate, and 0.3 parts by weight of 2-ethylhexyl mercaptoacetate was continuously added to the reactor over 240 minutes to initiate polymerization. At this point, 30 minutes after the addition of the monomer mixture, 0.7 parts by weight of sodium dioctyl sulfosuccinate was continuously added to the reactor. Additionally, 90 minutes after the monomer mixture was added, the stirring speed was changed to 165 rpm. Then, 150 minutes after the monomer mixture was added, 0.1 parts by weight of sodium formaldehyde sulfoxylate and 0.1 parts by weight of tert-butyl hydroperoxide were added sequentially to the reactor. After the monomer mixture addition was completed, polymerization was continued for 15 minutes, and then 0.05 parts by weight of sodium formaldehyde sulfoxylate and 0.05 parts by weight of tert-butyl hydroperoxide were added sequentially to the reactor. Next, the reactor temperature was raised to 80°C, and polymerization was continued for 30 minutes. Then, 0.05 parts by weight of sodium formaldehyde sulfoxylate and 0.05 parts by weight of tert-butyl hydroperoxide were added sequentially to the reactor, and polymerization was continued for another 30 minutes. Finally, the reactor temperature was cooled to room temperature, and the polymerization was terminated to obtain an acrylic resin latex. At this point, the polymerization conversion rate was 99.2%.

[0149] A magnesium chloride aqueous solution containing 3 parts by weight of magnesium chloride in 200 parts by weight of deionized water was added to a stainless steel container. The solution was stirred with a paddle mixer while the temperature was raised to 95°C. Next, 100 parts by weight of acrylic resin latex (converted to solids content) was added to the magnesium chloride aqueous solution, causing the acrylic resin latex to coagulate. Then, 325 parts by weight of deionized water were added, and the temperature was raised to 98°C. The mixture was stirred for 1 minute to obtain an acrylic resin slurry. The slurry was then cooled to room temperature and vacuum filtered to remove water, yielding a filter cake containing trace amounts of water. Finally, the filter cake was dried at 75°C for 10 hours using a hot air dryer to obtain a white powdery acrylic resin.

[0150] A white powdered acrylic resin was dispersed in ethanol at a concentration of 25% by weight and stirred for 30 minutes. The ethanol was then removed by vacuum filtration, yielding an acrylic resin containing trace amounts of ethanol. Next, the obtained acrylic resin was dispersed in deionized water at a concentration of 25% by weight and stirred for 30 minutes. The water was then removed by vacuum filtration. The resin was then dried at 75°C for 10 hours using a hot air dryer, yielding a white powdered acrylic resin with impurities removed. The obtained acrylic resin was then spread in a stainless steel container and heated at 200°C for 1 hour using a hot air dryer. The heated, solidified acrylic resin was then pulverized using a mixer to obtain granular acrylic resin B. Acrylic resin B has a Mw of 86,000, an Mw / Mn ratio of 1.84, and contains 24% by weight of structural units containing lactone rings. It should be noted that the acrylic resin B, which is a precursor of acrylic resin, has hydroxyl and ester groups. By heating, the hydroxyl and ester groups undergo a cyclization condensation reaction to form a structural unit containing an lactone ring.

[0151] (Manufacturing of acrylic resin film B)

[0152] Granular acrylic resin B is fed into a KZW15TWIN-45MG (TECHNOVEL) co-rotating twin-screw extruder with a 15mm diameter T-die at the outlet and an L / D ratio of 45. Film is formed by melt extrusion at an extrusion temperature of 260°C. The sheet exiting the T-die is cooled and wound up via casting rollers to obtain a roll of film with a width of 160mm and a thickness of 160μm. Next, 100mm × 100mm films are cut from the roll of film with both sides parallel to the extrusion direction. The films are then placed in a biaxial stretching device and simultaneously biaxially stretched at a stretching temperature of 137°C and a stretching speed of 100mm / min, with a stretching ratio of 2 times in both the parallel and perpendicular directions relative to the extrusion direction. The film is then removed and cooled at room temperature to obtain an acrylic resin film B with a thickness of 40μm.

[0153] (Comparative Example 1)

[0154] (Manufacturing of acrylic resin C)

[0155] As the acrylic resin supplied to the co-rotating twin-screw extruder, PMMA resin SUMIPEX MH (manufactured by Sumitomo Chemical Co., Ltd.) was used. Otherwise, acrylic resin C granules were obtained in the same manner as in the production of acrylic resin A. Acrylic resin C had a Mw of 115,000, an Mw / Mn ratio of 1.58, and contained 5.8% by weight of structural units including glutarimide rings.

[0156] (Manufacturing of acrylic resin film C)

[0157] By using granules of acrylic resin C instead of granules of acrylic resin A, and changing the stretching temperature to 129°C, acrylic resin film C is obtained in the same manner as in (the manufacture of acrylic resin film A).

[0158] (Comparative Example 2)

[0159] (Manufacturing of acrylic resin D)

[0160] As the acrylic resin supplied to the co-rotating twin-screw extruder, PMMA resin ACRYPET VH5 (manufactured by Mitsubishi Chemical Corporation) was used. Otherwise, acrylic resin D granules were obtained in the same manner as in the production of acrylic resin A. Acrylic resin D had a Mw of 81,500, an Mw / Mn ratio of 1.57, and contained 5.9% by weight of structural units including glutarimide rings.

[0161] (Manufacturing of acrylic resin film D)

[0162] By using acrylic resin D granules instead of acrylic resin A granules and changing the stretching temperature to 134°C, acrylic resin film D is obtained in the same manner as in (the manufacture of acrylic resin film A).

[0163] Table 1 shows the evaluation results of the resistance to roller contamination of acrylic resin films.

[0164] [Table 1]

[0165]

[0166] As shown in Table 1, the acrylic resins and acrylic resin films of Examples 1 and 2 have high resistance to roller contamination and heat resistance during film making.

[0167] In contrast, the acrylic resin of Comparative Example 1 had a MMA dimer content of 600 ppm by weight, resulting in low resistance to roller contamination and heat during film formation. Furthermore, the acrylic resin film of Comparative Example 1 had an MMA dimer content of 400 ppm by weight, a water contact angle as high as 70°, and a MMA dimer reduction rate of 33.3%, thus also exhibiting low resistance to roller contamination and heat during film formation.

[0168] The acrylic resin of Comparative Example 2 had a MMA dimer content of 450 ppm by weight, resulting in low resistance to roller contamination and heat during film formation. Furthermore, the acrylic resin film of Comparative Example 2 had an MMA dimer content of 250 ppm by weight, a water contact angle as high as 72°, and a MMA dimer reduction rate of 44.4%, thus also exhibiting low resistance to roller contamination and heat during film formation.

Claims

1. A method for manufacturing an acrylic resin molded article, comprising a method for manufacturing an acrylic resin molded article. The method includes a step of melt-molding an acrylic resin using an extruder, the acrylic resin comprising methyl methacrylate units and having a main chain comprising one or more ring structures selected from the group consisting of glutarimide rings, lactone rings, maleic anhydride rings, glutaric anhydride rings, and maleimide rings. When the content of methyl methacrylate dimer in the acrylic resin and the content of methyl methacrylate dimer in the acrylic resin molded body are set as A [weight ppm] and B [weight ppm] respectively, the reduction rate of methyl methacrylate dimer calculated by formula: [(AB) / A]×100 is more than 50%.

2. A method for manufacturing an acrylic resin molded article, comprising a method for manufacturing an acrylic resin molded article. The method includes a step of melt-molding an acrylic resin using an extruder, the acrylic resin comprising methyl methacrylate units and having a glass transition temperature of 120°C or higher. When the content of methyl methacrylate dimer in the acrylic resin and the content of methyl methacrylate dimer in the acrylic resin molded body are set as A [weight ppm] and B [weight ppm] respectively, the reduction rate of methyl methacrylate dimer calculated by formula: [(AB) / A]×100 is more than 50%.

3. The method for manufacturing an acrylic resin molded article according to claim 1 or 2, wherein, The acrylic resin molded body is in the form of granules or film.

4. The method for manufacturing an acrylic resin molded article according to claim 1 or 2, wherein, The molecular weight dispersion (Mw / Mn) of the acrylic resin is greater than 1.

60.

5. The method for manufacturing an acrylic resin molded article according to claim 1 or 2, wherein, The content of methyl methacrylate dimer in the acrylic resin molded article is less than 200 ppm by weight.

6. The method for manufacturing an acrylic resin molded article according to claim 1 or 2, wherein, A 2cm square test piece was cut from a 160μm thick film formed by molding the acrylic resin in a glass petri dish with a diameter of 4cm and a height of 1cm. The glass petri dish was covered with a glass plate with aluminum foil covering the entire surface and heated at 285°C for 1 hour. The relative fluorescence intensity of the volatiles transferred to the surface of the aluminum foil was less than 2000 RFU.

7. The method for manufacturing an acrylic resin molded article according to claim 1 or 2, further comprising: The process of polymerizing methyl methacrylate in a solvent or dispersion medium to obtain a polymer, and The process of reacting the polymer to obtain the acrylic resin.

8. The method for manufacturing an acrylic resin molded article according to claim 7, wherein, The methyl methacrylate is polymerized by solution polymerization, suspension polymerization or emulsion polymerization.

9. An acrylic resin comprising methyl methacrylate units, wherein the main chain comprises one or more ring structures selected from the group consisting of glutarimide rings, lactone rings, maleic anhydride rings, glutaric anhydride rings, and maleimide rings. The content of methyl methacrylate dimer is less than 200 ppm by weight.

10. The acrylic resin according to claim 9, wherein, A 2cm square test piece cut from a 160μm thick film formed from the acrylic resin was placed in a glass petri dish with a diameter of 4cm and a height of 1cm. The glass petri dish was covered with a glass plate with aluminum foil covering the entire surface and heated at 285°C for 1 hour. The relative fluorescence intensity of the volatiles transferred to the surface of the aluminum foil was less than 2000 RFU.

11. The acrylic resin according to claim 9 or 10, wherein the molecular weight dispersion (Mw / Mn) is 1.60 or higher.

12. An acrylic resin film comprising a resin, said resin comprising methyl methacrylate units, and the main chain comprising one or more ring structures selected from the group consisting of glutarimide rings, lactone rings, maleic anhydride rings, glutaric anhydride rings, and maleimide rings. The content of methyl methacrylate dimer in the acrylic resin film is less than 200 ppm by weight.

13. The acrylic resin film according to claim 12, wherein the internal haze is less than 0.30%.

14. The acrylic resin film according to claim 12 or 13, wherein it is a polarizer protective film.

15. An acrylic resin comprising methyl methacrylate units, The acrylic resin has a glass transition temperature of 120°C or higher, and the content of methyl methacrylate dimer is less than 200 ppm by weight.

16. An acrylic resin film comprising an acrylic resin, said acrylic resin containing methyl methacrylate units, and having a glass transition temperature of 120°C or higher. The content of methyl methacrylate dimer in the acrylic resin film is less than 200 ppm by weight.

17. The acrylic resin film according to claim 16, wherein the water contact angle at 23°C is less than 70°.

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