Method for manufacturing resin molded articles and resin sheets

Abstract

To provide a method for producing a resin molding which can improve impact resistance while maintaining a high elastic modulus.SOLUTION: A method for producing a resin molding includes polymerizing a monomer (B) containing methyl (meth)acrylate, in the presence of a graft copolymer (A) containing a polymer chain (E) having a glass transition temperature (Tg) of lower than 20°C, and a polymer chain (D) having the Tg of 20°C or higher.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to a method for manufacturing resin molded articles and resin sheets. [Background technology]

[0002] Acrylic resin is widely used in display front panels for liquid crystal and organic EL displays, signage, lighting equipment, home appliances, vehicle interior and exterior materials, industrial materials, building materials, lenses, light guide plates, light concentrators, and optical films used in liquid crystal and organic EL displays, due to its excellent transparency, weather resistance, high elastic modulus, and surface hardness. However, although acrylic resin has a high elastic modulus, it is a brittle material that is susceptible to impact, and depending on the application, there is a requirement to improve impact resistance while maintaining a high elastic modulus. Acrylic resin molded articles (hereinafter also called cast sheets) obtained by the cast polymerization method, in which a liquid acrylic monomer mixture containing polymerizable components (hereinafter also called syrup) is injected into a mold and polymerized, exhibit high elastic modulus, weather resistance, and transparency, but there is a need for improved impact resistance. Furthermore, in the cast polymerization method, since the molded body is created by polymerizing the syrup after pouring it into a mold, it is also required that the viscosity of the injected syrup not be too high.

[0003] One known method for improving the impact resistance of cast sheets is to add a block copolymer containing a soft component to an acrylic monomer mixture. Patent Document 1 describes a method for obtaining a cast sheet (PMMA sheet) by polymerizing methyl methacrylate (MMA) in the presence of an ABA-type block copolymer consisting of a rubber component (B) and a polymethyl methacrylate (PMMA) component (A). Patent Document 2 describes a method for producing a cast sheet by adding a polymer consisting solely of rubber components and having initiators at both ends to a syrup mainly composed of MMA, and simultaneously carrying out cast polymerization and the synthesis of a block copolymer. [Prior art documents]

Patent Document

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the method described in Patent Document 1, as the amount of the ABA-type block copolymer added increases, the syrup viscosity increases proportionally, so the addition amount is limited, and there is a problem that the effect of improving the impact resistance of the molded product cannot be sufficiently obtained. In the method described in Patent Document 2, the polymer composed only of the rubber component has poor solubility in the monomer mixture mainly composed of MMA, and there is a problem that the addition amount is limited. Also, since the polymer to be added consists only of the rubber component which is a soft component, there is a problem that the elastic modulus of the molded product tends to decrease.

[0006] The present invention has been made in view of the above circumstances, and an object thereof is to provide a method for producing a resin molded product capable of improving impact resistance while maintaining a high elastic modulus.

Means for Solving the Problems

[0007] ​​​​​​​​​​​​ [3] A method for producing a resin molded article of [1] or [2], wherein the polymer chain (D) is a polymer chain derived from a macromonomer (d) represented by the following formula (1).

[0008] [ka]

[0009] (In equation (1), R and R 1 ~R n Each of these may independently be a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, or a heterocyclic group, and may have substituents. 1 ~X n Each of these is independently either a hydrogen atom or a methyl group. Z is a terminal group. n is a natural number between 2 and 10,000. [4] A method for producing a resin sheet, comprising cast polymerization of a polymerizable composition (Z) containing a polymer chain (E) having a glass transition temperature (Tg) of less than 20°C, a polymer chain (D) having a Tg of 20°C or higher, and a monomer (B) containing methyl (meth)acrylate. [5] A method for producing the resin sheet of [4], wherein the graft copolymer (A) has an α in the Mark-Houwink formula represented by the following formula (I) that is less than 0.6. η = K × M α …(I) (In the formula, η is the intrinsic viscosity, M is the absolute molecular weight, and K and α are constants.) [6] A method for producing a resin sheet according to [4] or [5], wherein the polymer chain (D) is a polymer chain derived from the macromonomer (d) represented by formula (1). [Effects of the Invention]

[0010] According to the present invention, a resin molded article can be obtained that has improved impact resistance while maintaining a high modulus of elasticity. [Modes for carrying out the invention]

[0011] The following describes in detail embodiments for carrying out the present invention, but the present invention is not limited to the following description and can be implemented in various ways within the scope of its gist. In this invention, "(meth)acrylic acid" means at least one selected from "acrylic acid" and "methacrylic acid." Also, "(meth)acrylate" refers to methacrylate or acrylate. "(meth)acryloyl" refers to "acryloyl" or "methacryloyl." In the present invention, "monomer" means an unpolymerized compound, and "repeating unit" means a constituent unit that makes up a polymer derived from the monomer, which is formed by the polymerization of the monomer. The "repeating unit" may be a unit directly formed by a polymerization reaction, or a part of the unit may be converted to a different structure by processing the polymer. In this invention, "mass%" indicates the content of a specific component in 100% of the total amount by mass. In the present invention, unless otherwise specified, a numerical range represented by "~" in this specification means a range that includes the numbers written before and after "~" as the lower and upper limits, and "A~B" means A or greater and B or less. In the present invention, "resin molded article" means an article formed when a polymerizable composition has solidified through a polymerization reaction and taken on an arbitrary shape.

[0012] In this invention, the Tg of the polymer chain is determined by adopting values ​​from known literature such as the Polymer Handbook (POLYMER HANDBOOK FOURTH EDITION 2003) as the Tg of the homopolymer of each monomer constituting the polymer chain, and can be calculated using Fox's formula depending on the monomer composition.

[0013] In this invention, the mass-average molecular weight of the copolymer is the mass-average molecular weight obtained as the relative molecular weight of the copolymer, and is determined using gel permeation chromatography (GPC). The calibration curve used to determine the relative molecular weight is prepared using standard polymers having known peak molecular weights. It is preferable to use standard polymers that are similar in properties to the polymer being measured, and when measuring copolymers, a calibration curve is prepared using 5 to 10 types of polymethyl methacrylate with known peak molecular weights. A differential refractometer (RI) is used as the detector. In this specification, the mass-average molecular weight may be denoted as "Mw" and the number-average molecular weight as "Mn".

[0014] ≪Method for manufacturing resin molded products≫ The method for producing the resin molded article of this embodiment (hereinafter also referred to as "molded article") comprises the step of polymerizing a monomer (B) containing (meth)acrylate in the presence of a specific graft copolymer (A). One embodiment in which the resin molded article is a resin sheet is a method for producing a resin sheet, which involves cast polymerization of a polymerizable composition (Z) containing a graft copolymer (A) and a monomer (B).

[0015] ≪Graft copolymer (A)≫ The graft copolymer (A) used in the present invention (hereinafter also referred to as "polymer (A)") has two or more polymer segments. Because the graft copolymer (A) has two or more chemically bonded polymer segments, it can improve impact resistance while maintaining a high modulus of elasticity. Furthermore, by introducing polymer segments that contribute to improved compatibility with monomer (B), the solubility in monomer (B) can be improved. Graft copolymer (A) has a branched structure, and compared to linear polymers, the viscosity increase of the polymerizable composition (Z) due to the addition of copolymer (A) is smaller. Therefore, performance can be improved by increasing the amount of copolymer (A) added.

[0016] The graft copolymer (A) is preferably a graft copolymer comprising a polymer chain (E) with a Tg of less than 20°C and a polymer chain (D) with a Tg of 20°C or higher. The polymer chain (E) functions as a soft segment, contributing to improved impact resistance. Polymer chain (D) contributes to improved compatibility with the resin after molding. The Tg of the polymer chain (E) is less than 20°C, preferably 10°C or lower, and more preferably 0°C or lower. The lower limit is not particularly limited, but from the viewpoint of handling the copolymer, -110°C or higher is preferred. The Tg of polymer chain (D) is 20°C or higher, preferably 55°C or higher, and more preferably 90°C or higher. The upper limit is not particularly limited, but from the viewpoint of the heat processability of the prepared resin molded article, 280°C or lower is preferred. The graft copolymer (A) may consist only of a graft copolymer containing polymer chains (E) with a Tg of less than 20°C and polymer chains (D) with a Tg of 20°C or higher, or it may contain a block copolymer containing polymer chains (E) with a Tg of less than 20°C and polymer chains (D) with a Tg of 20°C or higher, a polymer consisting of polymer chains (E) with a Tg of less than 20°C, and a polymer consisting of polymer chains (D) with a Tg of 20°C or higher.

[0017] [Branching degree α] The graft copolymer (A) is preferably a graft copolymer in which α in the Mark-Houwink formula represented by the following formula (I) is less than 0.6. η = K × M α …(I) (In the formula, η is the intrinsic viscosity, M is the absolute molecular weight, and K and α are constants.) The aforementioned α (also referred to as "branching degree α" in this specification) can be calculated from the slope of the logarithmic plot (Mark-Houwink plot) of intrinsic viscosity and absolute molecular weight measured using SEC-LS / DP. A smaller α indicates a greater degree of branching.

[0018] The more branched the graft copolymer (A) is, the more easily the increase in viscosity caused by blending copolymer (A) with monomer (B) is suppressed. This allows for the incorporation of a larger amount of graft copolymer (A), thereby further enhancing the performance improvement effect of graft copolymer (A). The degree of branching α of the graft copolymer (A) is preferably less than 0.6, more preferably 0.55 or less, and even more preferably 0.5 or less. When the degree of branching α is less than 0.6, the resulting molded article has good impact resistance.

[0019] The lower limit of Mw for the graft copolymer (A) is 240,000 or higher, which is preferable for good impact resistance of the molded article. 300,000 or higher is preferred, and 600,000 or higher is more preferable. On the other hand, the upper limit of Mw for the graft copolymer (A) is 3,500,000 or lower, which is preferable for good handling of the polymerizable composition (Z). 2,000,000 or lower is preferred, and 1,500,000 or lower is more preferable. The above upper and lower limits can be combined arbitrarily. Alternatively, the Mw of the graft copolymer (A) is between 240,000 and 3,500,000, preferably between 300,000 and 2,000,000, and more preferably between 600,000 and 1,500,000.

[0020] The graft copolymer (A) preferably has a polymer chain (D) derived from a macromonomer having a radically polymerizable unsaturated double bond at one end of a poly(meth)acrylate segment, and a polymer chain (E) derived from a monomer (e) copolymerizable with the macromonomer. Having macromonomer units results in good transparency, mechanical strength, and impact resistance of the resulting molded article. As the macromonomer, macromonomer (d) represented by general formula (1), described later, is preferred because it provides better impact resistance to the molded article. Macromonomers (d) and monomers (e) will be discussed later.

[0021] <Polymer chain (D)> The polymer chain (D) of the graft copolymer (A) is preferably a methyl methacrylate-based polymer chain (hereinafter referred to as "MMA-based polymer chain") having repeating units derived from methyl methacrylate (hereinafter referred to as "MMA units"). The MMA-based polymer chain contributes to improved compatibility with monomer (B). The polymer chain (D) is more preferably a polymer chain derived from the macromonomer (d) and is an MMA-based polymer chain.

[0022] [MMA-based polymer chains] When the polymer chain (D) of the graft copolymer (A) is an MMA-based polymer chain, the compatibility between the copolymer (A) and monomer (B) is good when preparing the polymerizable composition (Z). As a result, the transparency, mechanical strength, and impact resistance of the resulting molded article are excellent. The compatibility between the copolymer (A) and monomer (B) can be improved by designing the type and composition ratio of the repeating units constituting the MMA-based polymer chain and the type and composition ratio of the monomer (B) to be similar to each other.

[0023] The lower limit of the content of MMA units in the MMA-based polymer chain is not particularly limited, and can be 80% by mass or more, relative to 100% by mass of the total mass of the MMA-based polymer chain, as this results in good transparency, mechanical strength, and weather resistance of the resulting molded article. More preferably 90% by mass or more, and even more preferably 95% by mass or more. On the other hand, the upper limit of the content of MMA units is not particularly limited, and can be 100% by mass of MMA units or 99% by mass or less.

[0024] The lower limit of the content of MMA-based polymer chains in the graft copolymer (A) is not particularly limited, but can be 35% by mass or more based on 100% by mass of the total mass of copolymer (A) in order to improve the handling properties of copolymer (A). More preferably 37% by mass or more, even more preferably 38% by mass or more, and particularly preferably 40% by mass or more. On the other hand, the upper limit of the content of MMA-based polymer chains is not particularly limited, but can be 75% by mass or less based on 100% by mass of the total mass of copolymer (A) in order to reduce the amount of copolymer (A) used and obtain a modification effect with a small amount of additive. More preferably 70% by mass or less, even more preferably 65% ​​by mass or less, and particularly preferably 60% by mass or less. The above upper and lower limits can be combined arbitrarily. Alternatively, the content of MMA-based polymer chains in the graft copolymer (A) can be 35% to 75% by mass, based on 100% by mass of the total mass of copolymer (A). More preferably 37% to 70% by mass, even more preferably 38% to 65% by mass, and particularly preferably 40% to 60% by mass.

[0025] In the graft copolymer (A), the MMA-based polymer chain may contain repeating units derived from methacrylate other than MMA units (hereinafter referred to as "methacrylate units") in order to adjust the compatibility between copolymer (A) and monomer (B). Alternatively, the MMA-based polymer chain may contain repeating units derived from acrylate (hereinafter referred to as "acrylate units") in order to improve the thermal decomposition resistance of copolymer (A).

[0026] The lower limit of the acrylate unit content in the MMA polymer chain can be 0.5% by mass or more, based on 100% by mass of the total mass of the MMA polymer chain, in order to ensure good thermal decomposition resistance of copolymer (A). More preferably 2.0% by mass or more, and even more preferably 4.0% by mass or more. On the other hand, the upper limit of the acrylate unit content can be 20.0% by mass or less, based on 100% by mass of the total mass of the MMA polymer chain, in order to maintain good heat resistance, hardness, scratch resistance, weather resistance, transparency, and processability of the resulting resin molded article. More preferably 10.0% by mass or less, and even more preferably 5.0% by mass or less.

[0027] The monomers constituting the MMA-based polymer chain are not particularly limited as long as they are monomers copolymerizable with methyl methacrylate, and examples include the following a) to i). a) (meth)acrylate ester monomers other than methyl methacrylate, such as methyl acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, i-propyl (meth)acrylate, n-butyl (meth)acrylate, i-butyl (meth)acrylate, t-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-lauryl (meth)acrylate, n-stearyl (meth)acrylate, cyclohexyl (meth)acrylate, phenyl (meth)acrylate, benzyl (meth)acrylate, isobornyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, and phenoxyethyl (meth)acrylate. b) Hydroxyl group-containing (meth)acrylate monomers such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and glycerol (meth)acrylate. c) Carboxyl group-containing vinyl monomers such as (meth)acrylic acid, 2-(meth)acryloyloxyethylhexahydrophthalic acid, 2-(meth)acryloyloxypropylhexahydrophthalic acid, 2-(meth)acryloyloxyethyl phthalic acid, 2-(meth)acryloyloxypropyl phthalic acid, 2-(meth)acryloyloxyethyl maleic acid, 2-(meth)acryloyloxypropyl maleic acid, 2-(meth)acryloyloxyethyl succinic acid, 2-(meth)acryloyloxypropyl succinic acid, crotonic acid, fumaric acid, maleic acid, itaconic acid, monomethyl maleate, monomethyl itaconic acid, etc. d) Vinyl monomers containing acid anhydride groups such as maleic anhydride and itaconic anhydride. e) Epoxy group-containing vinyl monomers such as glycicyl (meth)acrylate, glycicyl α-ethyl acrylate, and 3,4-epoxybutyl (meth)acrylate. f) Vinyl monomers containing amino groups, such as dimethylaminoethyl (meth)acrylate and diethylaminoethyl (meth)acrylate. g) Vinyl monomers containing amide groups such as (meth)acrylamide, Nt-butyl(meth)acrylamide, N-methylol(meth)acrylamide, N-methoxymethyl(meth)acrylamide, N-butoxymethyl(meth)acrylamide, diacetone acrylamide, maleic acid amide, and maleimide. h) Vinyl monomers such as styrene, α-methylstyrene, vinyltoluene, (meth)acrylonitrile, vinyl chloride, vinyl acetate, and vinyl propionate. i) Polyfunctional vinyl monomers such as divinylbenzene, ethylene glycol di(meth)acrylate, 1,3-butylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, allyl(meth)acrylate, and N,N'-methylenebis(meth)acrylamide.

[0028] These monomers can be used individually or in combination of two or more. Among the monomers mentioned above, n-butyl methacrylate and 2-ethylhexyl methacrylate are preferred as monomers constituting the methacrylate unit. Among the monomers mentioned above, methyl acrylate, ethyl acrylate, and n-butyl acrylate are preferred as monomers constituting the acrylate unit in terms of availability.

[0029] Furthermore, in the graft copolymer (A), when polymerizing monomer (B) in the presence of copolymer (A), the impact resistance of the resulting molded article can be further improved by controlling the molecular weight of the MMA-based polymer chain to the extent that entanglement occurs between the MMA-based polymer chain in copolymer (A) and the polymer chain generated by the polymerization of monomer (B).

[0030] The lower limit of Mw of the MMA polymer chain is not particularly limited, and it can be set to 10,000 or more, more preferably 15,000 or more, and even more preferably 20,000 or more, in order to maintain good compatibility between the graft copolymer (A) and the monomer (B). Alternatively, the Mw of the MMA-based polymer chains contained in the graft copolymer (A) can be between 10,000 and 100,000. More preferably between 15,000 and 90,000, and even more preferably between 20,000 and 80,000.

[0031] <Polymer chain (E)> The monomer (e) units that make up the polymer chain (E) may be one type or two or more types. The monomer (e) can be selected from monomers copolymerizable with the macromonomer (d) such that the Tg of the polymer chain (E) is less than 20°C.

[0032] In the polymer chain (E), it is preferable that the monomer (e) unit contains repeating units derived from the acrylate (e1) described later (hereinafter also referred to as "acrylate (e1) unit"). The acrylate (e1) unit contributes to improving the impact resistance of the molded article.

[0033] In the polymer chain (E), it is preferable that the monomer (e) unit contains repeating units derived from aromatic vinyl (e2), which will be described later (hereinafter also referred to as "aromatic vinyl (e2) units"). The refractive index of the polymer chain (E) can be adjusted by introducing aromatic vinyl (e2) units. Aromatic vinyl (e2) units contribute to improving the transparency of the molded article in high-temperature environments.

[0034] In the graft copolymer (A), the lower limit of the content of aromatic vinyl (e2) units contained in the polymer chain (E) can be set to 15 to 30% by mass, more preferably 16 to 28% by mass, and even more preferably 17 to 25% by mass, based on 100% by mass of the total mass of monomer (e), in order to improve the transparency of the resulting molded article in a high-temperature environment.

[0035] The ratio of macromonomer (d) units to monomer (e) units in the graft copolymer (A) can be (d) units:(e) units = 35-75% by mass:65-25% by mass, based on 100% by mass of the total mass of copolymer (A). More preferably, (d) units:(e) units = 37-72%:63-28% by mass, even more preferably (d) units:(e) units = 38-70% by mass:62-30% by mass, and particularly preferably (d) units:(e) units = 40-65%:60-35% by mass. The handling properties of copolymer (A) are good if the lower limit of the macromonomer (d) unit content in 100% by mass of copolymer (A) is 35% by mass or more, or the upper limit of the monomer (e) unit content is 65% by mass or less. Furthermore, if the upper limit of the content of macromonomer (d) units in 100% by mass of copolymer (A) is 75% by mass or less, or the lower limit of the content of monomer (e) units is 25% by mass or more, the impact resistance of the resulting molded article can be maintained well.

[0036] [Method for producing graft copolymer (A)] One embodiment of a method for producing a graft copolymer (A) involves polymerizing a polymerizable mixture containing a polymerizable composition (X) described later and a polymerization initiator described later. The polymerizable composition (X) contains a macromonomer (d) represented by the general formula (1) and a monomer (e) copolymerizable with the macromonomer (d). The monomer (e) preferably contains an acrylate (e1) and an aromatic vinyl (e2).

[0037] In the method for producing the graft copolymer (A), the polymerization reaction is preferably carried out using a radical polymerization method. Examples of radical polymerization methods include bulk polymerization methods such as bulk polymerization and cast polymerization, or solution polymerization, and aqueous dispersion polymerization methods such as suspension polymerization and emulsion polymerization. Since the recovery process for copolymer (A) can be simplified, aqueous dispersion polymerization methods such as suspension polymerization and emulsion polymerization are preferred, and suspension polymerization is even more preferred because the resulting polymer particles are easy to handle. In suspension polymerization, copolymer (A) is obtained as spherical particles with an average particle size of approximately 5 μm to 1 mm. The resulting spherical particles are preferable because they are easy to handle and have good solubility in monomer (B). The reason for this is not entirely clear, but it is presumed that trace amounts of abnormal polymers and residual emulsifiers generated in emulsion polymerization cause foreign matter and thickening, resulting in suspension polymerization being superior to emulsion polymerization. Details of the suspension polymerization method will be described later.

[0038] Alternatively, in a method for producing the graft copolymer (A), the polymerization reaction may be carried out using a bulk polymerization method such as a bulk polymerization method or a cast polymerization method, and the method may include a step of heating the polymerizable mixture to polymerize it. Furthermore, with solution polymerization, it is possible to produce macromonomer (d) by solution polymerization and then directly add monomer (e) and a thermal polymerization initiator to the solution to carry out a copolymerization reaction and obtain graft copolymer (A).

[0039] In the method for producing the graft copolymer (A), it is preferable that the upper limit of the sulfur-containing chain transfer agent content in the polymerizable mixture is less than 0.01 parts by mass per 100 parts by mass of the polymerizable composition (X). If the upper limit of the sulfur-containing chain transfer agent content is less than 0.01 parts by mass, it is possible to suppress the broadening of the copolymer's compositional distribution, thereby improving the impact resistance of the molded article. There is no particular lower limit to the sulfur-containing chain transfer agent content, and it is more preferable that the product does not contain a sulfur-containing chain transfer agent. The aforementioned sulfur-containing chain transfer agent refers to mercaptan compounds such as n-butyl mercaptan and n-octyl mercaptan that are added as chain transfer agents during polymerization to adjust the molecular weight of the polymer.

[0040] The method for controlling the mass-average molecular weight (Mw) of the graft copolymer (A) is not particularly limited and may include adjusting the polymerization method, the type and amount of polymerization initiator added, the amount of chain transfer agent added, the polymerization temperature, etc.

[0041] [Polymerizable composition (X)] Polymerizable composition (X) is one of the raw materials for graft copolymer (A).

[0042] The content of the macromonomer (d) in the polymerizable composition (X) is preferably 35% by mass or more, as this improves the handling properties of the graft copolymer (A) and maintains good impact resistance of the molded article.

[0043] More specifically, the content ratio of macromonomer (d) (Xd, unit: mass%) and monomer (e) (Xe, unit: mass%) in the polymerizable composition (X) can be Xd:Xe = 35~75% mass:65~25% mass. Xd:Xe = 37~72%:63~28% mass% is more preferable, Xd:Xe = 38~70% mass:62~30% mass% is even more preferable, and Xd:Xe = 40~65%:60~45% mass% is particularly preferable. If the lower limit of the content ratio of macromonomer (d) in 100% mass of the polymerizable composition (X) is 35% mass or more, or the upper limit of the content ratio of monomer (e) is 65% mass or less, the copolymer (A) will have good handling properties. Furthermore, if the lower limit of the content of monomer (e) in 100% by mass of polymerizable composition (X) is 25% by mass or more, or the upper limit of the content of macromonomer (d) is 75% by mass or less, the amount of copolymer (A) used can be reduced, and the impact resistance of the molded article can be improved with a small amount of additive.

[0044] [Production of copolymers by suspension polymerization] In the method for producing the graft copolymer (A), the case in which the polymerization reaction is carried out using suspension polymerization will be described in detail below. When producing a graft copolymer (A) using suspension polymerization, there are two methods: one in which the macromonomer (d) production process, including steps i) to v) below, and the graft copolymer (A) production process are carried out separately; and another in which, instead of steps i) to ii) below, the macromonomer (d) production process, including steps a) to b) below, and the graft copolymer (A) production process are carried out continuously.

[0045] i) Polymerizable composition (X) preparation process A syrup is prepared by dissolving bead-shaped macromonomers (d) produced by suspension polymerization in a solution containing monomer (e), and this is designated as polymerizable composition (X). When preparing the polymerizable composition (X), the mixture containing macromonomer (d) and monomer (e) can be heated at a temperature below the boiling point of monomer (e) to promote the dissolution of macromonomer (d). The temperature for preparing the polymerizable composition (X) is preferably in the range of 20°C to 100°C, and more preferably in the range of 40°C to 80°C. If the radical polymerization initiator used does not react at the temperature for preparing the polymerizable composition (X), the radical polymerization initiator can be mixed with the polymerizable composition (X) to obtain a polymerizable mixture, and then the polymerizable mixture can be heated.

[0046] ii) Dissolution step of radical polymerization initiator If the radical polymerization initiator reacts at the temperature at which the polymerizable composition (X) obtained in step i) is prepared, the polymerizable composition (X) is cooled to room temperature or below, and then the radical polymerization initiator is added and uniformly dissolved to obtain a polymerizable mixture. When the radical polymerization initiator is added, the temperature of the polymerizable composition (X) is preferably at or below the temperature obtained by subtracting 15°C from the 10-hour half-life temperature of the radical polymerization initiator.

[0047] iii) Preparation of aqueous solution After mixing the polymerizable mixture and the aqueous solution, the mixture is stirred to prepare a suspension in which droplets of the polymerizable mixture are dispersed in the aqueous solution. The aqueous solution is an aqueous solution for dispersing the polymerizable mixture and may contain a dispersant, an electrolyte, and other auxiliary agents. By appropriately selecting a combination of the dispersant and the electrolyte, the dispersibility of the droplets of the polymerizable mixture formed in the aqueous solution can be controlled when the polymerizable mixture is dispersed in the aqueous solution. When using water in an aqueous solution, it is preferable to use deionized water because it allows for good dispersion of droplets of the polymerizable mixture. Examples of dispersants include alkali metal salts of poly(meth)acrylic acid, copolymers of alkali metal salts of (meth)acrylic acid and (meth)acrylic acid esters, copolymers of alkali metal salts of (meth)acrylate sulfoalkyl and (meth)acrylic acid esters, alkali metal salts of polystyrene sulfonic acid, copolymers of alkali metal salts of styrene sulfonic acid and (meth)acrylic acid esters, or copolymers consisting of combinations of these monomers; polyvinyl alcohol with a degree of saponification of 70-100%, methylcellulose, starch, and hydroxyapatite. These can be used alone or in combination of two or more. Among these, copolymers of alkali metal salts of (meth)acrylate sulfoalkyl and (meth)acrylic acid esters and copolymers of alkali metal salts of (meth)acrylate and (meth)acrylic acid esters are preferred due to their good dispersion stability during suspension polymerization. The amount of dispersant added is, for example, in the range of 0.0005 to 0.5 parts by mass per 100 parts by mass of polymerizable composition (X). Examples of electrolytes include sodium carbonate, sodium sulfate, and manganese sulfate. The amount of electrolyte added is, for example, in the range of 0.01 to 1.0 parts by mass per 100 parts by mass of polymerizable composition (X).

[0048] a) Preparation process for polymerizable composition (X) The polymerizable composition (X) is prepared by adding a solution containing monomer (e) to a solution in which macromonomers (d) on beads produced by suspension polymerization are dispersed in an aqueous solution. The temperature at which macromonomers (d) are dissolved in the solution containing monomer (e) is preferably in the range of 20°C to 100°C, and more preferably in the range of 40°C to 80°C. In the polymerizable composition (X) preparation step, the monomer (e) may also be added to a suspension in which the macromonomer (d) is dispersed in an aqueous solution with an average particle size of 10 to 500 μm.

[0049] i) Dissolution step of radical polymerization initiator If the radical polymerization initiator reacts at the temperature at which the polymerizable composition (X) obtained in step (a) above is prepared, the polymerizable composition (X) is cooled to room temperature or below, and then the radical polymerization initiator is added and uniformly dissolved to obtain a polymerizable mixture. When the radical polymerization initiator is added, the temperature of the polymerizable composition (X) is preferably at or below the temperature obtained by subtracting 15°C from the 10-hour half-life temperature of the radical polymerization initiator.

[0050] iv) Polymerization reaction process Next, the obtained suspension is heated while stirring to start the polymerization reaction. It is preferable to remove dissolved oxygen from the polymerizable mixture and the aqueous solution by vacuum degassing or nitrogen purging before heating. The polymerization temperature when carrying out the polymerization reaction is an important condition for obtaining graft copolymer (A) in high yield. The polymerization temperature referred to here is the temperature of the suspension. The polymerization temperature is preferably 50°C to 90°C, more preferably 60°C to 86°C, and even more preferably 65°C to 82°C. If the polymerization temperature is too low, there is a concern that the reaction will proceed slowly and the polymerization time will be long. Also, if the polymerization temperature is too high, the cleavage of adduct radicals, which are reaction intermediates, will take precedence, and the yield of graft copolymer (A) tends to decrease. In the later stages of the polymerization reaction, the suspension can be heated to increase the reaction rate of the polymerizable composition (X) and to eliminate any unreacted radical polymerization initiator. The temperature at which the suspension is heated is preferably 80°C or higher, and more preferably 85°C or higher. The heating time can be determined by calculating the time it takes for the radical polymerization initiator to disappear, and is usually between 30 minutes and 2 hours.

[0051] v) Recovery process After the above steps, the suspension is cooled to below room temperature, and the resulting bead-shaped copolymer is recovered using a known method such as filtration. If necessary, washing steps to remove impurities such as dispersants and electrolytes, steps to remove beads containing air bubbles, drying steps, etc., can be performed. The final bead-shaped copolymer is designated as graft copolymer (A).

[0052] [Macromonomers (d)] The macromonomer (d) is one of the monomer raw materials for forming the graft copolymer (A), and is a compound represented by the following general formula (1).

[0053] [Chemical formula]

[0054] [In formula (1), R and R 1 ~R n each independently represent a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group or a heterocyclic group. X 1 ~X n each independently represent a hydrogen atom or a methyl group. Z represents a terminal group. n represents a natural number from 2 to 10,000.]

[0055] [R and R in formula (1) 1 ~R n In the general formula (1), the alkyl group, cycloalkyl group, aryl group or heterocyclic group of R and R 1 ~R n can have substituents.

[0056] Examples of the alkyl group of R and R 1 ~R n include, for example, a branched or straight-chain alkyl group having 1 to 20 carbon atoms. Specific examples include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, a t-butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, a tridecyl group, a tetradecyl group, a pentadecyl group, a hexadecyl group, a heptadecyl group, an octadecyl group, a nonadecyl group, and an icosyl group. Among these, from the viewpoint of availability, a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, a t-butyl group, a pentyl group, a hexyl group, a heptyl group, and an octyl group are preferred, a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, and a t-butyl group are more preferred, and a methyl group is particularly preferred.

[0057] ​ R and R 1 ~R n Examples of cycloalkyl groups include cycloalkyl groups having 3 to 20 carbon atoms. Specific examples include cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, cycloheptyl group, cyclooctyl group, t-butylcyclohexyl group, isobornyl group, adamantyl group, etc. Due to their availability, cyclopropyl group, cyclobutyl group, and adamantyl group are preferred.

[0058] R and R 1 ~R n Examples of aryl groups include aryl groups having 6 to 18 carbon atoms. Specific examples include phenyl groups, benzyl groups, and naphthyl groups.

[0059] R and R 1 ~R n Examples of heterocyclic groups include heterocyclic groups with 5 to 18 carbon atoms. Specific examples include γ-lactone groups, ε-caprolactone groups, and morpholine groups. Heteroatoms included in the heterocycle include oxygen atoms, nitrogen atoms, and sulfur atoms.

[0060] R or R 1 ~R n The substituents can be any group or atom selected from the group consisting of alkyl groups, aryl groups, carboxyl groups, alkoxycarbonyl groups (-COOR'), carbamoyl groups (-CONR'R''), cyano groups, hydroxyl groups, amino groups, amide groups (-NR'R''), halogen atoms, allyl groups, epoxy groups, alkoxy groups (-OR'), and hydrophilic or ionic groups. Examples of R' or R'' can be any group similar to R (excluding heterocyclic groups).

[0061] R or R 1 ~R n An example of an alkoxycarbonyl group as a substituent is a methoxycarbonyl group. R or R1 ~R n Examples of carbamoyl groups used as substituents include N-methylcarbamoyl groups and N,N-dimethylcarbamoyl groups. R or R 1 ~R n An example of an amide group as a substituent is the dimethylamide group. R or R 1 ~R n Examples of halogen atoms used as substituents include fluorine, chlorine, bromine, and iodine atoms. R or R 1 ~R n Examples of alkoxy groups used as substituents include alkoxy groups having 1 to 12 carbon atoms. A specific example is the methoxy group. R or R 1 ~R n Examples of hydrophilic or ionic substituents include alkali salts of carboxyl groups or sulfoxyl groups, poly(alkylene oxide) groups such as polyethylene oxide groups and polypropylene oxide groups, and cationic substituents such as quaternary ammonium bases.

[0062] R and R 1 ~R n Preferably, at least one selected from alkyl groups and cycloalkyl groups is used, with alkyl groups being more preferred. The alkyl group is preferably a methyl group, an ethyl group, an n-propyl group, or an i-propyl group, with the methyl group being more preferred from the viewpoint of availability.

[0063] [X in equation (1)] 1 ~X n ] In the above general formula (1), X 1 ~X n From the viewpoint of ease of synthesis of macromonomer (d) in the present invention, X 1 ~X n It is preferable that 80 mol% or more of the total moles are methyl groups.

[0064] [Z in equation (1)] In the general formula (1) above, Z is a terminal group of macromonomer (d) in the present invention. Examples of terminal groups of macromonomer (d) include hydrogen atoms and groups derived from radical polymerization initiators, similar to the terminal groups of polymers obtained by known radical polymerization.

[0065] The lower limit of the content of the macromonomer (d) units in the graft copolymer (A) is not particularly limited, but can be 35% by mass or more based on 100% by mass of the total mass of copolymer (A) in order to improve the handling properties of copolymer (A). More preferably 37% by mass or more, even more preferably 38% by mass or more, and particularly preferably 40% by mass or more. On the other hand, the upper limit of the content of the macromonomer (d) units is not particularly limited, but can be 75% by mass or less based on 100% by mass of the total mass of copolymer (A) in order to reduce the amount of copolymer (A) used and to obtain the effect of improving impact resistance with a small amount of additive. More preferably 70% by mass or less, even more preferably 65% ​​by mass or less, and particularly preferably 60% by mass or less. The above upper and lower limits can be combined arbitrarily. Alternatively, the content of the macromonomer (d) units in the graft copolymer (A) can be 35% by mass or more and 75% by mass or less, based on 100% by mass of the total mass of copolymer (A). More preferably 37% by mass or more and 70% by mass or less, even more preferably 38% by mass or more and 65% by mass or less, and particularly preferably 40% by mass or more and 60% by mass or less.

[0066] When polymerizing monomer (B) in the presence of a graft copolymer (A), which is a copolymer of macromonomer (d) and monomer (e), the impact resistance of the resulting molded article can be improved by controlling the molecular weight of the polymer chain consisting of macromonomer (d) units to the extent that the polymer chain produced by the polymerization of monomer (B) and the MMA-based polymer chain in copolymer (A) become entangled. Here, the inter-entanglement molecular weight Me of polymethyl methacrylate is known to be approximately 9,200 g / mol (Wu et al.: POLYMER ENGINEERING AND SCIENCE, JUNE 1992, Vol.32, No.12 p823). Therefore, the lower limit of Mw for macromonomer (d) can be 10,000 or more, more preferably 12,000 or more, and particularly preferably 15,000 or more. On the other hand, the upper limit of Mw for macromonomer (d) can be 1,000,000 or less, as this allows for good copolymerization between macromonomer (d) and monomer (e) and maintains good impact resistance of the molded article. A value of 500,000 or less is more preferable, and 100,000 or less is particularly preferable. The above upper and lower limits can be combined arbitrarily. Alternatively, the Mw of macromonomer (d) can be between 10,000 and 1,000,000. More preferably between 12,000 and 500,000, and particularly preferably between 15,000 and 100,000. The Mw of the macromonomer (d) refers to the mass-average molecular weight, which is the relative molecular weight obtained using gel permeation chromatography (GPC) and converted to (meth)acrylic polymer (PMMA).

[0067] [Raw material monomers for macromonomers (d)] The raw material monomer for producing macromonomer (d) contains methyl methacrylate as an essential component, and monomers copolymerizable with methyl methacrylate as other components. The monomers copolymerizable with methyl methacrylate can be the same monomers as those listed above as "monomers constituting MMA-based polymer chains" (a) to i)). These monomers can be used individually or in combination of two or more.

[0068] Among these monomers, methyl (meth)acrylate, n-butyl (meth)acrylate, lauryl (meth)acrylate, dodecyl (meth)acrylate, stearyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, glycidyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate are preferred in terms of the ease of obtaining the raw material monomers, and methyl (meth)acrylate, n-butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate are more preferred.

[0069] Furthermore, as raw material monomers for producing macromonomer (d), it is preferable that the resulting graft copolymer (A), polymerizable composition (Z) containing copolymer (A), and molded articles formed using polymerizable composition (Z) contain acrylate in part, as these have excellent resistance to thermal decomposition. Examples of the acrylates include methyl acrylate, ethyl acrylate, n-propyl acrylate, i-propyl acrylate, n-butyl acrylate, i-butyl acrylate, and t-butyl acrylate. Among these, methyl acrylate, ethyl acrylate, and n-butyl acrylate are preferred in terms of availability.

[0070] In the graft copolymer (A), the polymer chain consisting of macromonomer (d) units represented by general formula (1) can contribute to improving the compatibility between the graft copolymer (A) and the monomer (B). Therefore, by designing the type and composition ratio of the repeating units constituting the polymer chain consisting of macromonomer (d) units and the type and composition ratio of the monomer (B) to be similar to each other, the compatibility between the copolymer (A) and the monomer (B) can be improved.

[0071] A polymer chain consisting of macromonomer (d) units may contain 80% by mass or more of MMA units based on 100% by mass of the total mass of the polymer chain. More preferably, it may contain 90% by mass or more, and even more preferably, 95% by mass or more. The polymer chain may also contain methacrylate units other than MMA units.

[0072] The macromonomer (d) preferably contains acrylate units in order to improve the heat decomposition resistance of the graft copolymer (A). The upper limit of the acrylate unit content in the macromonomer (d) is preferably 20% by mass or less, more preferably 10% by mass or less, and particularly preferably 5% by mass or less, based on 100% by mass of the total mass of the macromonomer (d).

[0073] [Method for producing macromonomers (d)] Macromonomers (d) can be produced by known methods. Examples of methods for producing macromonomers include a method using a cobalt chain transfer agent (U.S. Patent No. 4680352), a method using an α-substituted unsaturated compound such as α-bromomethylstyrene as a chain transfer agent (International Publication No. 88 / 04304), a method of chemically bonding polymerizable groups (Japanese Patent Publication No. 60-133007, U.S. Patent No. 5147952), and a method by thermal decomposition (Japanese Patent Publication No. 11-240854). Among these methods, the method using a cobalt chain transfer agent is preferred because it involves fewer manufacturing steps and utilizes a catalyst with a high chain transfer constant.

[0074] Methods for producing macromonomer (d) using a cobalt chain transfer agent include, for example, bulk polymerization, solution polymerization, and aqueous dispersion polymerization methods such as suspension polymerization and emulsion polymerization. Among these, aqueous dispersion polymerization is preferred from the viewpoint of simplifying the macromonomer (d) recovery step, and suspension polymerization is particularly preferred. Furthermore, with solution polymerization, it is possible to obtain graft copolymer (A) by copolymerization reaction by adding monomer (e) and a thermal polymerization initiator directly without recovering macromonomer (d).

[0075] As the cobalt chain transfer agent used in the present invention, a cobalt chain transfer agent represented by the following general formula (2) can be used, for example, those described in Japanese Patent No. 3587530, Japanese Unexamined Patent Publication No. Hei 6-23209, Japanese Unexamined Patent Publication No. Hei 7-35411, U.S. Patent No. 45269945, U.S. Patent No. 4694054, U.S. Patent No. 4834326, U.S. Patent No. 4886861, U.S. Patent No. 5324879, International Publication No. 95 / 17435, Japanese Patent Publication No. Hei 9-510499, etc. can be used.

[0076] [ka] [In formula (2), R 1 ~R 4 Each of the following is independently an alkyl group, a cycloalkyl group, and an aryl group; each of the following is independently a F atom, a Cl atom, a Br atom, an OH group, an alkoxy group, an aryloxy group, an alkyl group, and an aryl group.

[0077] [Monomer(e)] Monomer (e) is one of the monomer raw materials that form the graft copolymer (A), and is a monomer that copolymerizes with macromonomer (d). The presence of monomer (e) units in the graft copolymer (A) improves the impact resistance of the resulting molded article. The copolymerization reaction mechanism between macromonomer (d) and monomer (e) is described in detail in the paper by Yamada et al. (Prog. Polym. Sci.31 (2006) pp. 835-877), etc. As monomer (e), monomers having a double bond and exhibiting radical polymerizability can be used alone or in combination of two or more.

[0078] [Acrylate (e1)] The monomer (e) preferably contains an acrylate (e1) which exhibits good copolymerization with the macromonomer (d). The presence of acrylate (e1) units in the copolymer (A) results in good impact resistance of the molded article.

[0079] Preferably, the acrylate (e1) has a glass transition temperature (Tg) upper limit of less than 20°C for the homopolymer of acrylate (e1). If the glass transition temperature (Tg) is less than 20°C, the impact resistance of the molded article can be improved.

[0080] The acrylate (e1) content in monomer (e) can be 65% by mass or more, based on 100% by mass of the total mass of monomer (e). More preferably 67 parts by mass or more, and particularly preferably 70% by mass or more.

[0081] As acrylate (e1), for example, monomers that have one acryloyl group in one molecule can be used from among the monomers listed above as "monomers constituting the MMA polymer chain" (a) to i)). These can be used alone or in combination of two or more.

[0082] [Aromatic vinyl (e2)] The monomer (e) preferably contains an aromatic vinyl (e2) which exhibits good copolymerization properties with the macromonomer (d). The inclusion of aromatic vinyl (e2) units in the graft copolymer (A) allows the refractive index of the polymer chain containing monomer (e) units to be matched to that of the polymer chain of monomer (B) mixed with copolymer (A), resulting in good transparency of the molded article at room temperature and high-temperature environments. The aromatic vinyl (e2) content in monomer (e) can be 15 to 30% by mass, based on 100% by mass of the total mass of monomer (e). 16 to 28% by mass is more preferable, and 17 to 25% by mass is particularly preferable.

[0083] The aromatic vinyl (e2) is not particularly limited and includes polymerizable compounds, for example. Specifically, examples include styrene, α-methylstyrene, o-methylstyrene, p-methylstyrene, o-ethylstyrene, p-ethylstyrene and pt-butylstyrene, vinylethylbenzene, vinyltoluene, vinylxylene, vinylnaphthalene, diphenylethylene, and divinylbenzene. These can be used individually or in combination of two or more. Among these, styrene is preferred from the viewpoint of practical properties and productivity.

[0084] [Other monomers (e3)] The monomer (e) may optionally include other monomers (e3) that exhibit good copolymerization with macromonomer (d) and aromatic vinyl (e2). Examples of monomers (e3) include (meth)acrylic acid, 2-(meth)acryloyloxyethylhexahydrophthalic acid, 2-(meth)acryloyloxypropylhexahydrophthalic acid, 2-(meth)acryloyloxyethyl phthalic acid, 2-(meth)acryloyloxypropyl phthalic acid, 2-(meth)acryloyloxyethyl maleic acid, 2-(meth)acryloyloxypropyl maleic acid, 2-(meth)acryloyloxyethyl succinic acid, 2-(meth)acryloyloxypropyl succinic acid, crotonic acid, fumaric acid, maleic acid, itaconic acid, and mono-maleic acid. Examples include vinyl monomers containing carboxyl groups such as methyl and monomethyl itaconic acid; vinyl monomers containing acid anhydride groups such as maleic anhydride and itaconic anhydride; vinyl monomers containing amide groups such as (meth)acrylamide, Nt-butyl(meth)acrylamide, N-methylol(meth)acrylamide, N-methoxymethyl(meth)acrylamide, N-butoxymethyl(meth)acrylamide, diacetone acrylamide, maleic acid amide, and maleimide; and vinyl monomers such as (meth)acrylonitrile, vinyl chloride, vinyl acetate, and vinyl propionate. These can be used individually or in combination of two or more.

[0085] Among the monomers listed above, methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, and 4-hydroxybutyl acrylate are preferred because they exhibit excellent rigidity and impact resistance in the molded product. Alternatively, among the above monomers, phenyl acrylate, benzyl acrylate, and phenoxyethyl acrylate are preferred because they can reduce the refractive index difference between the polymer chain obtained by polymerization of monomer (B) and the graft copolymer (A), thereby improving the transparency of the molded article. Alternatively, among the above monomers, methyl acrylate and ethyl acrylate are preferred because they exhibit good compatibility between macromonomer (d) and monomer (e), resulting in good transparency and impact resistance of the molded article.

[0086] [Radical polymerization initiator] When the polymerization reaction of polymerizable composition (X) is carried out in the presence of a radical polymerization initiator, known organic peroxides such as 2,4-dichlorobenzoyl peroxide and t-butyl peroxypivalate, or known azo compounds such as 2,2'-azobisisobutyronitrile and 2,2'-azobis(2,4-dimethylvaleronitrile) can be used as the radical polymerization initiator. The amount of radical polymerization initiator can be appropriately selected according to well-known techniques by those skilled in the art. The usual amount is 0.0001 to 10 parts by mass of radical polymerization initiator per 100 parts by mass of the total amount of polymerizable composition (X).

[0087] The polymerization temperature for polymerizing the polymerizable composition (X) can be appropriately selected according to the well-known techniques by those skilled in the art. The typical polymerization temperature is 50°C to 85°C.

[0088] [Tracking the synthesis reaction of copolymers] When producing the graft copolymer (A), the reaction rate of the macromonomer (d) can be measured to confirm whether the copolymer is being produced efficiently. The reaction rate of macromonomer (d) is the value obtained by dividing the total amount of macromonomer (d) before polymerization initiation by the total amount of macromonomer (d) converted into graft copolymer (A). The reaction rate of macromonomer (d) in the present invention is the value obtained by subtracting from 1.0 the value obtained by dividing the peak area of ​​macromonomer (d) after polymerization completion by the peak area of ​​macromonomer (d) before polymerization completion in the respective elution curves of the reaction solutions measured by HPLC (high-performance liquid chromatography) before polymerization commencement.

[0089] On the other hand, the reaction rate of monomer (e) is, for example, 1 H-NMR method and 13 It can be measured using nuclear magnetic resonance spectroscopy methods such as 13C-NMR, or gas chromatography (GC). The reaction rate of monomer(e) in the present invention is determined by the reaction solution before polymerization initiation and after polymerization completion. 1 Each measured by H-NMR 1 This value is obtained by subtracting from 1.0 the value obtained by dividing the peak area of ​​the proton of the double bond of monomer (e) after polymerization is complete in the 1H-NMR spectrum by the peak area of ​​the proton of the double bond of monomer (e) before polymerization begins. Since the reaction rate of monomer (e) obtained by the NMR method and the reaction rate of monomer (e) obtained by the GC method are equivalent, the reaction rate of monomer (e) can also be calculated using the GC method.

[0090] [Monomer (B)] In the present invention, the monomer (B) used in the production of the molded article may be a single monomer or a mixture of two or more monomers. Monomer (B) contains methyl (meth)acrylate; that is, it contains either or both methyl acrylate and methyl methacrylate. Preferably, monomer (B) contains at least methyl methacrylate.

[0091] In a molded article obtained by polymerizing monomer (B) in the presence of graft copolymer (A), monomer (B) forms a matrix phase. The total content of methyl (meth)acrylate is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, particularly preferably 80% by mass or more, and may also be 100% by mass, based on 100% by mass of the total mass of monomer (B). If the lower limit of the methyl (meth)acrylate content relative to monomer (B) is 50% by mass or more per 100% by mass of the total mass of monomer (B), the molded article is likely to have good heat resistance, hardness, scratch resistance, weather resistance, transparency, and processability. The content of methyl methacrylate is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, particularly preferably 80% by mass or more, and may also be 100% by mass, relative to 100% by mass of monomer (B).

[0092] Monomer (B) may contain one or more monomers other than methyl (meth)acrylate in order to improve various physical properties of the molded article, such as mechanical strength and elastic modulus. Other monomers can be used, for example, the monomers listed above as "monomers constituting the MMA polymer chain" (a) to i) above, as well as monomers similar to those mentioned above. Other specific examples of monomers include (meth)acrylic acid esters having alicyclic hydrocarbon groups with 6 to 20 carbon atoms to reduce hygroscopicity, (meth)acrylic acid esters having linear or branched hydrocarbon groups with 3 to 10 carbon atoms, and polyfunctional acrylate monomers to improve mechanical strength, such as polyol polyacrylate, alkylene glycol polyacrylate or allyl acrylate, ethylene glycol diacrylate, 1,3-butylene glycol diacrylate or 1,4-butylene glycol diacrylate, dipentaerythritol hexaacrylate, and polyfunctional methacrylate monomers, such as polyol polymethacrylate, alkylene glycol polymethacrylate or allyl methacrylate, ethylene glycol dimethacrylate, 1,3-butylene glycol dimethacrylate or 1,4-butylene glycol dimethacrylate, divinylbenzene or trivinylbenzene.

[0093] ≪Method for manufacturing resin molded products≫ The method for producing the resin molded article of this embodiment includes a step of polymerizing monomer (B) in the presence of graft copolymer (A). Specifically, a polymerizable composition (Z) containing a graft copolymer (A) and a monomer (B) is prepared, and if necessary, it is filled into a mold, and the monomer (B) is polymerized to obtain a molded article.

[0094] The polymerizable composition (Z) can be prepared by dissolving the graft copolymer (A) in the monomer (B). Additives may be added to the polymerizable composition (Z) as needed. Examples of additives include chain transfer agents for molecular weight adjustment, various stabilizers such as antioxidants, UV absorbers, and heat stabilizers; colorants such as inorganic pigments, organic pigments, and dyes; conductivity imparting agents such as carbon black and ferrite; and inorganic fillers, lubricants, plasticizers, organic peroxides, neutralizing agents, and crosslinking agents.

[0095] The blending ratio of the graft copolymer (A) and monomer (B) is preferably such that the polymer chain (E) content is 5 to 25% by mass, and more preferably 10 to 20% by mass, relative to 100% by mass of the total mass of the graft copolymer (A) and monomer (B). When the content of the polymer chain (E) is 10% by mass or more, the molded article exhibits excellent impact resistance, and when it is 20% by mass or less, the molded article exhibits excellent elastic modulus.

[0096] The shape of the resin molded article is not particularly limited, but when the resin molded article is a resin sheet, it is preferable to prepare a polymerizable composition (Z), fill it into a mold for sheet molding, and polymerize (cast polymerization) to obtain a resin sheet. Specifically, a polymerizable composition (Z) is mixed with a polymerization initiator to prepare a syrup, and then a resin molded article can be manufactured by polymerizing the syrup while it is sealed in a mold (for example, a mold consisting of two parallel plates placed with a gap between them, a sealing material positioned in the gap between the two plates along the perimeter of the plates, and clamps to hold them in place). There are no restrictions on the material of the mold, but considering factors such as smoothness, heat resistance, and release from the resulting resin molded product, glass or metal (such as stainless steel) is usually used, and glass is preferred when polymerization is carried out by irradiation with active energy rays. The internal dimensions of the mold are determined by the desired size and shape of the resin molded product and are not particularly limited, however, when manufacturing a sheet-like resin molded product, for example, they are generally set to a thickness range of 1 mm to 20 mm. If the syrup contains a thermal polymerization initiator, polymerization of the polymerizable components in the syrup is usually initiated by heating the mold. If the heat of reaction associated with polymerization is not adequately removed or if there is an uneven accumulation of heat, the resulting resin molded article may have surface defects or internal foaming. To avoid these issues, circulating hot water or circulating hot air is usually applied as a heat transfer medium. The polymerization temperature is usually 30 to 140°C, and the polymerization time is usually 2 to 35 hours, although this is determined by the conditions under which polymerization is carried out by heating as described above, the type and amount of polymerization initiator and chain transfer agent used, the composition of the monomer mixture, and the desired size of the resin molded product. The polymerization temperature may be changed during the process. For example, polymerization at 30 to 80°C for 1 to 30 hours, followed by polymerization at 110 to 140°C for 1 to 5 hours is preferable from the viewpoint of not leaving behind unpolymerized monomers (B) that can cause defects in appearance. If the above-mentioned syrup contains a photopolymerization initiator, the polymerizable components in the syrup can be polymerized by irradiation with active energy rays. As such active energy rays, light rays, electromagnetic waves, particle beams, and combinations thereof can be used, but from the viewpoint of polymerization rate, availability of irradiation equipment, and cost, ultraviolet light or electron beams are preferred, and ultraviolet light is more preferred. The activated energy beams used for irradiation can be delivered using known equipment. For electron beams (EB), an appropriate accelerating voltage is 0.1 to 10 MeV, and an irradiation dose is 1 to 500 kGy. For ultraviolet irradiation, high-pressure mercury lamps, ultra-high-pressure mercury lamps, carbon arc lamps, metal halide lamps, xenon lamps, chemical lamps, LEDs, etc., that emit light in the 150-450 nm wavelength range can be used. The integrated light intensity of the active energy rays is typically 10-20000 mJ / cm². 2 The range is 30-5000 mJ / cm². 2 A range of 10 mJ / cm is preferred. Below 10 mJ / cm, the polymerization rate of syrup tends to decrease, and 20,000 mJ / cm is preferable. 2 Using too much may cause the resulting resin molded product to become discolored. When irradiating the above-mentioned syrup with active energy rays, the relative humidity is preferably 30% or less, and more preferably 10% or less, from the viewpoint of suppressing the decomposition of the syrup. After polymerization is complete, the mold can be removed to obtain a resin molded product.

[0097] According to the manufacturing method of this embodiment, as shown in the examples described later, a resin molded article with improved impact resistance can be obtained while maintaining a high modulus of elasticity. [Examples]

[0098] The present invention will be described in more detail below using examples, but the present invention is not limited to these examples. In the following, "parts" refers to "parts by mass".

[0099] <Measurement method> The following measurement method was used.

[0100] [Mass-average molecular weight (Mw) and number-average molecular weight (Mn) of macromonomer (d)] The Mw and Mn of macromonomer (d) were measured using gel permeation chromatography (GPC). 10 mg of the macromonomer (d) to be measured was dissolved in 10 ml of tetrahydrofuran, and the resulting solution, filtered through a 0.45 μm filter, was used as the sample for GPC measurement. A gel permeation chromatography analyzer (Tosoh Corporation, model name: HLC-8320) was used, with a polymer measurement guard column (Tosoh Corporation, product name: TSK-GUARD COLUMN SUPER HH) and two polymer measurement columns (Tosoh Corporation, product name: TSK-GEL SUPER HM-H) connected in series. A differential refractometer (RI) was used as the detector. Measurements were performed under the following conditions: separation column temperature: 40°C, mobile phase: tetrahydrofuran, mobile phase flow rate: 0.6 mL / min, sample injection volume: 10 μl. Several types of polymethyl methacrylate with known molecular weights (manufactured by Polymer Laboratories, peak molecular weight (Mp) 1,560 to 19,500,000) were used as standard polymers to create calibration curves and determine Mw and Mn.

[0101] [Mass-average molecular weight (Mw) and number-average molecular weight (Mn) of copolymer (A)] The Mw and Mn of copolymer (A) were measured using gel permeation chromatography (GPC). 10 mg of the copolymer to be measured was dissolved in 10 ml of tetrahydrofuran, and the resulting solution, filtered through a 0.45 μm filter, was used as the sample for GPC measurement. A high-performance liquid chromatography (HLC-8320, manufactured by Tosoh Corporation) was used, with a polymer measurement guard column (TSK-GUARD COLUMN SUPER HH, manufactured by Tosoh Corporation) and one ultra-high molecular weight measurement column (TSK-GEL GMHHR-H, manufactured by Tosoh Corporation) connected in series. A differential refractometer (RI) was used as the detector. Measurements were performed under the following conditions: separation column temperature: 40°C, mobile phase: tetrahydrofuran, mobile phase flow rate: 0.6 mL / min, sample injection volume: 10 μl. Several types of polymethyl methacrylate with known molecular weights (manufactured by Polymer Laboratories, peak molecular weight (Mp) 1,560 to 19,500,000) were used as standard polymers to create calibration curves, and the relative molecular weights Mw and Mn, calculated in terms of polymethyl methacrylate, were determined.

[0102] [Degree of branching α of copolymer (A)] Copolymer (A) was used as the target of measurement. The absolute molecular weight (M) and intrinsic viscosity ([η]) were measured using gel permeation chromatography (GPC) and a light scattering detector (LS) under the following measurement conditions, and the degree of branching α was determined from the slope of the resulting Mark-Houwink plot. Equipment: SEC 1260 Infinity II, manufactured by Agilent. LS: Multi-angle light scattering detector DAWN HELEOS II (Wyatt) Column: Two TSK guardcolumn HXL-H+TSKgel GMHXL (manufactured by Tosoh Corporation) and one TSKgel 3000HXL (manufactured by Tosoh Corporation) are connected in series. Column temperature: 40°C. Mobile phase: Stabilized tetrahydrofuran (THF), injection volume: 100 μL, flow rate: 1 mL / min. Sample concentration: 3 mg / mL.

[0103] <Evaluation Method> The following evaluation method was used. [Charpy impact test] As an indicator of the impact resistance of resin sheets, a Charpy impact tester (manufactured by Toyo Seiki Co., Ltd., product name: DG-CP) was used, and the Charpy impact strength (unit: kJ / m²) was measured in accordance with JIS K7111. 2 The Charpy impact strength was measured. Specifically, test pieces (without notches) made by cutting the sheet to be measured to a width of 10 mm and a length of 80 mm were used, and five pieces were tested at a time using a 15 J hammer. The average value was used as the measurement result for Charpy impact strength. The following criteria were used for evaluation. (Judgment criteria) AA: Charpy impact strength is 30 kJ / m 2 That's all. A: Charpy impact strength is 20 kJ / m 2 More than 30kJ / m 2 less than. B: Charpy impact strength is 20 kJ / m 2 less than.

[0104] [Bending test] As an indicator of the rigidity of the resin sheet, the flexural modulus (unit: MPa) was measured using a Tensilon universal testing machine (manufactured by Orientec Co., Ltd., product name: RTC-1250A) in accordance with JIS K7171. Specifically, test specimens cut from the resin sheet were used as the test subjects, and the flexural modulus was determined from the stress-strain curve obtained under conditions of room temperature of 23°C and a test speed of 2 mm / min. A flexural modulus of 1500 MPa or higher was judged as AA.

[0105] <Ingredients> The abbreviations for the compounds used in the following examples are as follows: MMA: Methyl methacrylate (trade name: Acryester® M, manufactured by Mitsubishi Chemical Corporation). MA: Methyl acrylate (manufactured by Mitsubishi Chemical Corporation). EA: Ethyl acrylate (manufactured by Mitsubishi Chemical Corporation). BA: n-butyl acrylate (manufactured by Mitsubishi Chemical Corporation). St: Styrene (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.). Chain transfer agent (1): Chain transfer catalyst produced in Production Example 2. Dispersant (1): The dispersant produced in Production Example 1. Polymerization initiator (1): 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate (manufactured by NOF Corporation, trade name: Perocta-O). Polymerization initiator (2): 2,2'-Azobis(2-methylbutyronitrile) (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., trade name: V-59). Polymerization initiator (3): t-hexyl peroxypivalate (manufactured by NOF Corporation, trade name: Perhexyl PV).

[0106] [Manufacturing Example 1: Synthesis of Dispersant (1)] In a reaction apparatus equipped with a stirrer, condenser, and thermometer, 61.6 parts of a 17% by mass potassium hydroxide aqueous solution, 19.1 parts of MMA, and 19.3 parts of deionized water were charged. The mixture in the reaction apparatus was then stirred at room temperature, and after confirming the exothermic peak, it was stirred for 4 hours. After this, the reaction mixture in the reaction apparatus was cooled to room temperature to obtain an aqueous potassium methacrylate solution. Next, 900 parts of deionized water, 70 parts of 42% by mass sodium 2-sulfoethyl methacrylate aqueous solution (manufactured by Mitsubishi Chemical Corporation, trade name: Acryester SEM-Na), 16 parts of the above potassium methacrylate aqueous solution, and 7 parts of MMA were added to a polymerization apparatus equipped with a stirrer, condenser, and thermometer, and stirred. The liquid in the reaction apparatus was heated to 50°C while purging nitrogen into the polymerization apparatus. 0.053 parts of V-50 (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., 2,2'-azobis(2-methylpropionamidine) dihydrochloride, trade name) was added to the polymerization apparatus as a polymerization initiator, and the liquid in the reaction apparatus was heated to 60°C. After the addition of the polymerization initiator, 1.4 parts of MMA were added every 15 minutes for a total of 5 times (total amount of MMA: 7 parts). After this, the liquid in the polymerization apparatus was kept at 60°C for 6 hours while stirring, and then cooled to room temperature to obtain a clear aqueous solution of dispersant (1) with a solid content of 8% by mass.

[0107] [Manufacturing Example 2: Synthesis of Chain Transfer Agent (1)] In a synthesis apparatus equipped with a stirring device, 2.00 g (8.03 mmol) of cobalt(II) acetate tetrahydrate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., Wako Special Grade), 3.86 g (16.1 mmol) of diphenylglyoxime (manufactured by Tokyo Chemical Industry Co., Ltd., EP Grade), and 100 ml of diethyl ether that had been deoxygenated beforehand by nitrogen bubbling were added under a nitrogen atmosphere and stirred at room temperature for 2 hours. Next, 20 ml of boron trifluoride diethyl ether complex (Tokyo Chemical Industries, Ltd., EP grade) was added, and the mixture was stirred for a further 6 hours. The resulting solution was filtered, the solid was washed with diethyl ether, and dried at 20°C under pressure of 100 MPa or less for 12 hours to obtain 5.02 g (7.93 mmol, yield 99% by mass) of the brownish solid chain transfer agent (1).

[0108] [Production Example 3: Synthesis of Macromonomer (d-1)] In a polymerization apparatus equipped with a stirrer, condenser, and thermometer, 145 parts of deionized water, 0.1 parts of sodium sulfate (Na2SO4), and 0.26 parts by mass of dispersant (1) (8% solids by mass) prepared in Production Example 1 were added and stirred to obtain a homogeneous aqueous solution. Next, 95 parts of MMA, 5.0 parts of MA, 0.0012 parts of chain transfer agent (1) prepared in Production Example 2, and 0.25 parts of polymerization initiator (1) were added to obtain an aqueous dispersion. Next, the polymerization apparatus was thoroughly purged with nitrogen, the aqueous dispersion was heated to 80°C and held for 3 hours, then heated to 90°C and held for 2 hours. After that, the reaction solution was cooled to 40°C to obtain an aqueous suspension of macromonomers. This aqueous suspension was filtered through a filter cloth, the filtrate was washed with deionized water, and the filtrate was dried at 40°C for 16 hours to obtain a dried product of macromonomer (d-1). The Mn and Mw of the obtained macromonomer (d-1) were measured using the method described above. The Mn value was 20,700 and the Mw value was 37,600.

[0109] [Manufacturing Example 4: Synthesis of Copolymer (A-1)] An aqueous suspension containing 60 parts by mass of macromonomer (d-1) was obtained using the same method as in Production Example 3. Specifically, 145 parts of deionized water, 0.1 parts of sodium sulfate (Na2SO4), and 0.26 parts by mass of dispersant (1) (8% solids by mass) prepared in Production Example 1 were added to a polymerization apparatus equipped with a stirrer, a condenser, and a thermometer, and stirred to obtain a homogeneous aqueous solution. Next, 57 parts of MMA, 3 parts of MA, 0.0015 parts of chain transfer agent (1) prepared in Production Example 2, and 0.15 parts of polymerization initiator (1) as a polymerization initiator were added to obtain an aqueous dispersion. Then, the polymerization apparatus was thoroughly purged with nitrogen, the aqueous dispersion was heated to 80°C and held for 3 hours, and then heated to 90°C and held for 2 hours to obtain an aqueous suspension of macromonomer (d-1). Next, the resulting reaction solution (aqueous suspension) was cooled to 60°C, 33.2 parts of BA and 6.8 parts of St were added, and the mixture was stirred for 1 hour to dissolve the macromonomer (d-1) in BA and St, obtaining a dispersion (polymerizable composition (X)). Next, after cooling to 40°C, 0.5 parts of polymerization initiator (2) were added and stirred to dissolve. The dispersion was heated to 80°C and held for 5 hours, then heated to 90°C and held for 1 hour. After cooling to below 40°C, it was filtered through a filter cloth and the filtrate was washed with deionized water. The filtrate was then dried under reduced pressure at 40°C for 12 hours to obtain bead-shaped copolymer (A-1). The Mn, Mw, and α of copolymer (A-1) were measured using the method described above. The results are shown in Table 1 (the same method applies hereafter).

[0110] [Manufacturing Example 5: Synthesis of Copolymer (A-2)] In Production Example 4, the amount of macromonomer in the aqueous suspension was changed to 50 parts by mass, and the amounts of BA and St added were changed to 41.5 parts BA and 8.5 parts St. Otherwise, suspension polymerization was carried out in the same manner as in Production Example 4 to obtain a bead-shaped copolymer (A-2).

[0111] [Manufacturing Example 6: Synthesis of Copolymer (A-3)] In Production Example 4, the amount of macromonomer in the aqueous suspension was changed to 40 parts by mass, and the amounts of BA and St added were changed to 49.8 parts BA and 10.2 parts St. Otherwise, suspension polymerization was carried out in the same manner as in Production Example 4 to obtain a bead-shaped copolymer (A-3).

[0112] Copolymers (A-1) to (A-3) include graft copolymers containing polymer chains (E) formed by the polymerization of BA and St, and polymer chains (D) derived from macromonomer (d-1). In copolymers (A-1) to (A-3), the Tg of polymer chain (E), determined from the compositions of BA and St used in production examples 4 to 6, was -38.4°C, and the Tg of polymer chain (D), determined from the composition of macromonomer (d-1), was 98.6°C.

[0113] [Table 1]

[0114] [Examples 1-5: Manufacturing of resin sheets (resin molded products)] Polymerizable compositions (Z) were prepared with the compositions shown in Table 2. Specifically, in each example formulation, the graft copolymer (A) was dissolved in MMA, and the polymerization initiator (3) was added to prepare polymerizable composition (Z). The obtained polymerizable composition (Z) was used in the next step after removing dissolved oxygen under reduced pressure. Next, the polymerizable composition (Z) was poured into a cell formed by a gasket and two pieces of tempered glass. The cell size (internal dimensions) was 100 mm in length, 100 mm in width, and 3 mm in thickness. A cell filled with polymerizable composition (Z) was heated in a hot water atmosphere at 80°C for 40 minutes, and then cast polymerized under conditions of heating in an air atmosphere at 120°C for another 60 minutes. As a result, the monomer components in the polymerizable composition (Z) polymerized, and a cured resin sheet (molded article) was obtained within the cell. The obtained resin sheets were subjected to Charpy impact tests (without notches) and bending tests using the method described above. The results are shown in Table 2 (the same method applies hereafter).

[0115] [Reference example 1] In this example, polymethyl methacrylate resin (Acrypet VH 001, manufactured by Mitsubishi Chemical Corporation) was used instead of the graft copolymer (A). The Acrypet pellets were previously ground into a fine powder using a stamp mill (Nittokagaku Co., Ltd., model name: ANS-143). Specifically, a polymerizable composition (Z) was prepared by dissolving polymethyl methacrylate resin in MMA according to the formulation shown in Table 2 and adding a polymerization initiator. The resin sheet was then manufactured in the same manner as in Example 1.

[0116] [Table 2]

[0117] As shown in the results in Table 2, Examples 1 to 5, in which a graft copolymer (A) was dissolved in monomer (B), which is methyl methacrylate, and subjected to a polymerization reaction, showed improved impact resistance while maintaining a high modulus of elasticity compared to Reference Example 1, in which only methyl methacrylate was polymerized.

Claims

1. A method for producing a resin molded article, comprising polymerizing a monomer (B) containing methyl (meth)acrylate in the presence of a graft copolymer (A) comprising a polymer chain (E) having a glass transition temperature (Tg) of less than 20°C and a polymer chain (D) having a Tg of 20°C or higher, The polymer chain (D) is a polymer chain derived from a macromonomer (d) represented by the following formula (1), The content ratio of repeating units derived from methyl methacrylate is 80% by mass or more with respect to the total mass of the polymer chain (D), The content ratio of repeating units derived from acrylate (e1) is 65% by mass or more relative to the total mass of the polymer chain (E), and the glass transition temperature (Tg) of the homopolymer of acrylate (e1) is less than 20°C. The polymer chain (D) has a content of 35 to 75% by mass and the polymer chain (E) has a content of 65 to 25% by mass, based on 100% by mass of the total mass of the graft copolymer (A). The content ratio of methyl methacrylate is 80% by mass or more with respect to the total mass of the monomer (B), A method for producing a resin molded article, wherein the content ratio of the polymer chain (E) is 5 to 20% by mass relative to the total mass of the graft copolymer (A) and the monomer (B). 【Chemistry 1】 (In equation (1), R and R １ ~R ｎ Each of these may independently be a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, or a heterocyclic group, and may have substituents. １ ~X ｎ R' and R'' are each independently a hydrogen atom or a methyl group. Z is a terminal group. n is a natural number between 2 and 10,000. The substituent is a group or atom selected from the group consisting of alkyl groups, aryl groups, carboxyl groups, alkoxycarbonyl groups (-COOR'), carbamoyl groups (-CONR'R''), cyano groups, hydroxyl groups, amino groups, amide groups (-NR'R''), halogen atoms, allyl groups, epoxy groups, alkoxy groups (-OR'), and hydrophilic or ionic groups, and R' or R'' are each independently a group similar to R (except heterocyclic groups).

2. The method for producing a resin molded article according to claim 1, wherein the graft copolymer (A) has an α of less than 0.6 in the Mark-Houwink formula represented by the following formula (I). η=K×M α …(I) (In the formula, η is the intrinsic viscosity, M is the absolute molecular weight, and K and α are constants.)

3. A method for producing a resin sheet, comprising cast polymerization of a polymerizable composition (Z) containing a polymer chain (E) having a glass transition temperature (Tg) of less than 20°C, a polymer chain (D) having a Tg of 20°C or higher, and a monomer (B) containing methyl (meth)acrylate, The polymer chain (D) is a polymer chain derived from a macromonomer (d) represented by the following formula (1), The content ratio of repeating units derived from methyl methacrylate is 80% by mass or more with respect to the total mass of the polymer chain (D), The content ratio of repeating units derived from acrylate (e1) is 65% by mass or more relative to the total mass of the polymer chain (E), and the glass transition temperature (Tg) of the homopolymer of acrylate (e1) is less than 20°C. The polymer chain (D) has a content of 35 to 75% by mass and the polymer chain (E) has a content of 65 to 25% by mass, based on 100% by mass of the total mass of the graft copolymer (A). The content ratio of methyl methacrylate is 80% by mass or more with respect to the total mass of the monomer (B), A method for producing a resin sheet, wherein the content ratio of the polymer chain (E) is 5 to 20% by mass relative to the total mass of the graft copolymer (A) and the monomer (B). 【Chemistry 2】 (In formula (1), R and R １ ~R ｎ are each independently a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group or a heterocyclic group, which may have a substituent. X １ ~X ｎ are each independently a hydrogen atom or a methyl group. Z is a terminal group. n is a natural number from 2 to 10,000. The substituent is a group or atom selected from the group consisting of an alkyl group, an aryl group, a carboxy group, an alkoxycarbonyl group (—COOR'), a carbamoyl group (—CONR'R''), a cyano group, a hydroxy group, an amino group, an amide group (—NR'R''), a halogen atom, an allyl group, an epoxy group, an alkoxy group (—OR'), and a group or atom showing hydrophilicity or ionic property, and the R' or R'' is each independently a group similar to the above R (excluding a heterocyclic group).)

4. The method for producing a resin sheet according to claim 3, wherein the graft copolymer (A) has an α of less than 0.6 in the Mark-Houwink formula represented by the following formula (I). η=K×M α …(I) (In the formula, η is the intrinsic viscosity, M is the absolute molecular weight, and K and α are constants.)

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