Thermoplastic resin composition and method for producing the same, molded article, film, and laminate

Abstract

To provide a thermoplastic resin composition comprising a methacrylic copolymer that includes methyl methacrylate units and one or more isopropenyl aromatic compound units, the thermoplastic resin composition exhibiting superior heat resistance, rigidity, and thermal decomposition resistance.SOLUTION: A thermoplastic resin composition of the present disclosure comprises: 1-99 mass% of a methacrylic copolymer (A) composed of 40-99 mass% of methyl methacrylate units, 1-40 mass% of one or more isopropenyl aromatic compound units (UI), and 0-30 mass% of one or more other units (UO); 99-1 mass% of a thermoplastic resin (B), other than the methacrylic copolymer (A), having a deflection temperature under load of 60-150°C as measured in accordance with JIS K 7191 A method; and 1-1000 ppm of an organic disulfide compound (C).SELECTED DRAWING: None

Description

Technical Field

[0001] The present disclosure relates to a thermoplastic resin composition, a method for producing the same, a molded article, a film, and a laminate.

Background Art

[0002] Thermoplastic resins (compositions) are used in a wide range of fields due to their excellent properties. In recent years, thermoplastic resins (compositions) have been required to have higher heat resistance and rigidity with the complication, enlargement, and thinning of molded articles. In response to this requirement, a technique of blending a methacrylic copolymer containing a methyl methacrylate (MMA) unit and an isopropenyl aromatic compound unit such as an α-methylstyrene (αMSt) unit with a thermoplastic resin has been proposed.

[0003] For example, Patent Document 1 discloses a transparent heat-resistant resin composition containing a methyl methacrylate (MMA)-styrene (St) copolymer and a methyl methacrylate (MMA)-α-methylstyrene (αMSt) copolymer (Claim 1). Patent Document 2 discloses a heat-resistant resin composition containing a polycarbonate resin and an α-methylstyrene (αMSt)-methyl methacrylate (MMA)-styrene (St) copolymer (Claim 1). Patent Document 3 discloses a thermoplastic resin composition containing a polybutylene terephthalate resin and an α-methylstyrene (αMSt) copolymer containing a methyl methacrylate (MMA) unit and an α-methylstyrene (αMSt) unit (Claim 1). Patent Document 4 discloses a thermoplastic resin composition containing a polyamide resin and a methyl methacrylate (MMA)-α-methylstyrene (αMSt)-maleic anhydride (Mah) copolymer (Claim 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

[0005] However, methacrylic copolymers containing MMA units and isopropenyl aromatic compound units such as αMSt units tend to have a relatively low thermal decomposition temperature. Therefore, in a thermoplastic resin composition containing this copolymer, the copolymer may thermally decompose during heating and melting during the production and molding process of the resin composition, increasing the amount of residual monomer in the resin composition and potentially reducing heat resistance and / or rigidity. In addition, if the residence time in the heat-melted state is prolonged during the production and molding process of the resin composition, appearance defects such as foaming and the generation of gel-like foreign substances may occur due to the thermal decomposition of the methacrylic copolymer.

[0006] The present disclosure has been made in view of the above circumstances, and an object thereof is to provide a thermoplastic resin composition containing a methacrylic copolymer containing methyl methacrylate units and one or more isopropenyl aromatic compound units, having good heat resistance, rigidity, and thermal decomposition resistance. [Means for Solving the Problems]

[0007] The present disclosure provides the following thermoplastic resin compositions [1] to

[11] , and methods for producing the same, molded articles, films, and laminates. [1] 1 to 99% by mass of a methacrylic copolymer (A) composed of 40 to 99% by mass of methyl methacrylate units, 1 to 40% by mass of one or more isopropenyl aromatic compound units (UI), and 0 to 30% by mass of one or more other units (UO), and 99 to 1% by mass of a thermoplastic resin (B) whose deflection temperature under load measured in accordance with JIS K 7191 Method A is 60 to 150°C, excluding the methacrylic copolymer (A), and 1 to 1000 ppm of an organic disulfide compound (C), a thermoplastic resin composition.

[0008] [2] The thermoplastic resin composition of [1], wherein one or more isopropenyl aromatic compound units (UI) contain α-methylstyrene units. [3] The thermoplastic resin composition of [1] or [2], wherein the methacrylic copolymer (A) contains, as other units (UO), aromatic vinyl compound units other than isopropenyl aromatic compound units. [4] The thermoplastic resin composition according to any one of [1] to [3], wherein the methacrylic copolymer (A) contains, as other units (UO), one or more ring structure units (UR) selected from the group consisting of acid anhydride units, maleimide units, and lactone ring units.

[0009] [5] The thermoplastic resin composition according to any one of [1] to [4], wherein the glass transition temperature of the methacrylic copolymer (A) is 120 to 150°C. [6] The thermoplastic resin composition according to any one of [1] to [5], wherein one or more organic disulfide compounds (C) contain di-tert-dodecyl disulfide (DDS). [7] The thermoplastic resin composition according to any one of [1] to [6], wherein the total light transmittance of a 3 mm thick flat plate made of the thermoplastic resin composition, measured in accordance with JIS K 7361-1, is 80% or more.

[0010] [8] A molded article containing the thermoplastic resin composition according to any one of [1] to [7]. [9] A film containing the thermoplastic resin composition according to any one of [1] to [7].

[10] A laminate containing a layer made of the thermoplastic resin composition according to any one of [1] to [7].

[0011]

[11] A process (S1) for producing a methacrylic copolymer (AC) added with an organic disulfide compound, which contains a methacrylic copolymer (A) and an organic disulfide compound (C); A method for producing a thermoplastic resin composition according to any one of [1] to [7], which includes a step (S2) of melt-kneading 1 to 99% by mass of the methacrylic copolymer (AC) added with an organic disulfide compound and 99 to 1% by mass of a thermoplastic resin (B).

Effects of the Invention

[0012] According to the present disclosure, a thermoplastic resin composition can be provided which contains a methacrylic copolymer containing a methyl methacrylate unit and one or more isopropenyl aromatic compound units, and has good heat resistance, rigidity, and thermal decomposition resistance.

Modes for Carrying Out the Invention

[0013] In this specification, unless otherwise specified, the "unit" contained in the polymer is a repeating unit contained in the polymer, and is a monomer unit derived from a raw material monomer or a derivative unit derived from one or more monomer units. In this specification, (meth)acrylic is a general term for acrylic and methacrylic, and the same applies to (meth)acrylonitrile and the like.

[0014] [Thermoplastic Resin Composition] The thermoplastic resin composition of the present disclosure contains one or more methacrylic copolymers (A) composed of 40 to 99% by mass of methyl methacrylate (MMA) units, 1 to 40% by mass of one or more isopropenyl aromatic compound units (UI), and 0 to 30% by mass of one or more other units (UO). The thermoplastic resin composition of the present disclosure further contains one or more thermoplastic resins (B) whose heat distortion temperature (HDT) measured in accordance with JIS K 7191 A method is 60 to 150°C, other than the methacrylic copolymer (A). In the thermoplastic resin composition of the present disclosure, the content of the methacrylic copolymer (A) (the total amount in the case of multiple types unless otherwise specified) is 1 to 99% by mass, and the content of the thermoplastic resin (B) (the total amount in the case of multiple types unless otherwise specified) is 99 to 1% by mass.

[0015] (Organic disulfide compound (C)) The thermoplastic resin composition of the present disclosure contains 1 to 1000 ppm of one or more organic disulfide compounds (C) as an additive. The lower limit is preferably 10 ppm, more preferably 20 ppm, still more preferably 30 ppm, still more preferably 50 ppm, particularly preferably 70 ppm, and most preferably 100 ppm. The upper limit is preferably 800 ppm, more preferably 700 ppm, still more preferably 600 ppm, still more preferably 500 ppm, still more preferably 400 ppm, particularly preferably 300 ppm, and most preferably 250 ppm.

[0016] As described in the section of [Background Art], generally, a methacrylic copolymer containing MMA units and isopropenyl aromatic compound units such as αMSt units tends to have a relatively low thermal decomposition temperature. The thermal degradation of this copolymer includes a thermal decomposition reaction accompanied by a depolymerization reaction. Therefore, in a thermoplastic resin composition containing this copolymer, when heated and melted during the production and molding process of the resin composition, the copolymer thermally decomposes, increasing the amount of residual monomer in the resin composition, and there is a risk of deterioration in heat resistance and / or rigidity.

[0017] According to the research of the present inventors, the following has been found. In the thermoplastic resin composition of the present disclosure containing an appropriate amount of the organic disulfide compound (C), during heating and melting such as during the production and molding process of the resin composition, due to the presence of an appropriate amount of the organic disulfide compound (C), the thermal degradation and thermal decomposition accompanied by the depolymerization reaction of the copolymer are effectively suppressed, and the deterioration of physical properties such as the heat resistance and rigidity of the resin composition is effectively suppressed. An appropriate amount of the organic disulfide compound (C) can also contribute to the thermal stabilization of the thermoplastic resin (B). For example, when the thermoplastic resin (B) contains monomer units that undergo thermal decomposition through a radical chain mechanism such as a depolymerization reaction and a radical transfer reaction involving β-scission, the presence of an appropriate amount of the organic disulfide compound (C) effectively suppresses the thermal deterioration and thermal decomposition of the thermoplastic resin (B), and effectively suppresses the degradation of physical properties such as the heat resistance and rigidity of the resin composition.

[0018] It is considered that the thiyl radical generated by the cleavage of the disulfide bond in the organic disulfide compound (C) can effectively capture the alkyl radical generated by the thermal deterioration or thermal decomposition of the methacrylic copolymer (A) and the specific thermoplastic resin (B), thereby effectively suppressing the thermal deterioration and thermal decomposition of these resins. For the above reasons, the thermoplastic resin composition of the present disclosure can be excellent in heat resistance, rigidity, and thermal decomposition resistance (thermal stability).

[0019] Examples of the organic disulfide compound (C) include dialkyl disulfide compounds such as diethyl disulfide, di-n-propyl disulfide, di-n-butyl disulfide, di-sec-butyl disulfide, di-tert-butyl disulfide, di-n-amyl disulfide, di-tert-amyl disulfide, di-tert-hexyl disulfide, di-n-octyl disulfide, di-tert-octyl disulfide, di-n-dodecyl disulfide, di-tert-dodecyl disulfide (DDS), di-n-stearyl disulfide, ethyl-n-propyl disulfide, ethyl-tert-butyl disulfide, ethyl-sec-butyl disulfide, and n-propyl-isopropyl disulfide; aromatic disulfide compounds such as diphenyl disulfide, dibenzyl disulfide (DBS), and di-p-tolyl disulfide; cyclic disulfide compounds such as ditrimethylene disulfide, ditetramethylene disulfide, and dicyclohexyl disulfide; amino group-containing disulfide compounds such as cystine and diaminodiphenyl disulfide; disulfides of carboxylic acids or their derivatives such as dithiodiglycolic acid, dithiodipropionic acid, and 2-ethylhexyl dithiodiglycolate; and unsaturated bond-containing disulfide compounds such as diallyl disulfide. Among them, dialkyl disulfide compounds and / or aromatic disulfide compounds are preferred. From the viewpoint of the cleavage temperature of the disulfide bond, as the dialkyl disulfide compound, di-tert-alkyl disulfides such as di-tert-dodecyl disulfide (DDS) are preferred. As the aromatic disulfide compound, dibenzyl disulfide (DBS) is preferred. The addition timing of the organic disulfide compound (C) is not particularly limited and can be arbitrary, such as before, during, or after the polymerization of the methacrylic copolymer (A) or the thermoplastic resin (B), and during the production of the thermoplastic resin composition.

[0020] (Physical properties) The thermoplastic resin composition of the present disclosure can be excellent in transparency. The total light transmittance measured in accordance with JIS K7136-1 of a 3-mm thick flat plate made of the thermoplastic resin composition of the present disclosure is preferably 80% or more. The lower limit is more preferably 82%, still more preferably 85%, particularly preferably 87%, and most preferably 90%. The upper limit is not particularly limited, and is, for example, 98% or 95%.

[0021] The thermoplastic resin composition of the present disclosure can be excellent in heat resistance and rigidity even under load. The heat distortion temperature (HDT) measured in accordance with JIS K7191 Method A of a test piece having a length of 80 mm, a width of 10 mm, and a thickness of 4 mm made of the thermoplastic resin composition of the present disclosure is preferably 70°C or higher. The lower limit is more preferably 72°C, still more preferably 75°C, particularly preferably 80°C, and most preferably 90°C. The upper limit is not particularly limited, and is, for example, 130°C or 120°C.

[0022] The thermoplastic resin composition of the present disclosure can be excellent in rigidity. The flexural modulus measured in accordance with JIS K7171 of a test piece having a length of 80 mm, a width of 10 mm, and a thickness of 4 mm made of the thermoplastic resin composition of the present disclosure is preferably 2000 MPa or more. The lower limit is more preferably 2200 MPa, still more preferably 2500 MPa, particularly preferably 2800 MPa, and most preferably 3000 MPa. The upper limit is not particularly limited, and is, for example, 5000 MPa or 4000 MPa. For the specific evaluation methods of the total light transmittance, the heat distortion temperature (HDT), and the flexural modulus, refer to the section of [Examples] described later.

[0023] (Methacrylic copolymer (A)) The content of the methacrylic copolymer (A) in the thermoplastic resin composition of the present disclosure is 1 to 99% by mass. The lower limit is preferably 3% by mass, more preferably 5% by mass, still more preferably 10% by mass, particularly preferably 15% by mass, and most preferably 20% by mass. The upper limit is preferably 95% by mass, more preferably 90% by mass, particularly preferably 85% by mass, and most preferably 80% by mass. If the content of the methacrylic copolymer (A) in the thermoplastic resin composition of the present disclosure is at least the above lower limit value, it can have excellent rigidity, and if it is at most the above upper limit value, it can have excellent impact resistance.

[0024] The methacrylic copolymer (A) contains methyl methacrylate (MMA) units and one or more isopropenyl aromatic compound units (UI), and may further contain one or more other units (UO).

[0025] The content of MMA units in the methacrylic copolymer (A) is 40 to 99% by mass. The lower limit value is preferably 45% by mass, more preferably 50% by mass, still more preferably 55% by mass, particularly preferably 60% by mass, and most preferably 65% by mass. The upper limit value is preferably 95% by mass, more preferably 90% by mass, particularly preferably 85% by mass, and most preferably 80% by mass.

[0026] The content (total amount in the case of multiple types unless otherwise specified) of one or more isopropenyl aromatic compound units (UI) in the methacrylic copolymer (A) is 1 to 40% by mass. The lower limit value is preferably 5% by mass, more preferably 10% by mass, and particularly preferably 15% by mass. The upper limit value is preferably 35% by mass, more preferably 30% by mass, particularly preferably 25% by mass, and most preferably 20% by mass.

[0027] If the content of the isopropenyl aromatic compound unit (UI) is less than the above lower limit, the heat resistance of the methacrylic copolymer (A) may be insufficient. If the content of the isopropenyl aromatic compound unit (UI) exceeds the above upper limit, the polymerizability, thermal decomposition resistance, and molding processability of the methacrylic copolymer (A) may decrease. If the content of the isopropenyl aromatic compound unit (UI) exceeds the above upper limit, it becomes difficult to control the copolymerization of the isopropenyl aromatic compound (I), and it may become difficult to stably produce a methacrylic copolymer (A) with a uniform composition such as the content of the isopropenyl aromatic compound unit (UI). Variations in the composition such as the content of the isopropenyl aromatic compound unit (UI) may lead to a decrease in mechanical properties such as heat resistance and rigidity.

[0028] If the content of the MMA unit and the content of the isopropenyl aromatic compound unit (UI) are within the above ranges, the methacrylic copolymer (A) can have good transparency, heat resistance, thermal decomposition resistance, polymerizability, and molding processability. Also, if the content of the MMA unit and the content of the isopropenyl aromatic compound unit (UI) are within the above ranges, the copolymerization of the isopropenyl aromatic compound (I) in the methacrylic copolymer (A) can be relatively easily controlled, and a methacrylic copolymer (A) with a uniform composition such as the content of the isopropenyl aromatic compound unit (UI) can be stably produced, and a methacrylic copolymer (A) with good mechanical properties such as heat resistance and rigidity can be stably produced.

[0029] The methacrylic copolymer (A) is obtained by copolymerizing methyl methacrylate (MMA), one or more isopropenyl aromatic compounds (I), and optionally one or more other monomers (O). Examples of the isopropenyl aromatic compound (I) include alkyl-substituted isopropenylbenzenes such as isopropenylbenzene (α-methylstyrene (αMSt)), isopropenylnaphthalene, isopropenyltoluene, isopropenylethylbenzene, isopropenylpropylbenzene, isopropenylbutylbenzene, isopropenylpentylbenzene, isopropenylhexylbenzene, and isopropenyloctylbenzene. From the viewpoint of ease of obtaining raw materials and the like, it is preferable that the one or more isopropenyl aromatic compounds (I) include one or more alkyl-substituted isopropenylbenzenes, and it is particularly preferable that they include isopropenylbenzene (α-methylstyrene (αMSt)).

[0030] Examples of the other monomer (O) include vinyl monomers (V) having one polymerizable unsaturated bond in one molecule, other than methyl methacrylate (MMA) and isopropenyl aromatic compounds (I). Examples of the vinyl monomer (V) include methyl acrylate; alkyl (meth)acrylates such as ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate; aryl (meth)acrylates such as phenyl (meth)acrylate; and cycloalkyl (meth)acrylates such as cyclohexyl (meth)acrylate and norbornenyl (meth)acrylate. (Meth)acrylic acid esters other than MMA are mentioned. Other examples of the vinyl monomer (V) include (meth)acrylic acid, (meth)acrylamide, and (meth)acrylonitrile. Other examples of the vinyl monomer (V) include styrene (St); alkyl-substituted styrenes such as o-, m-, or p-methylstyrene, 2,4-dimethylstyrene, 2,5-dimethylstyrene, 3,4-dimethylstyrene, 3,5-dimethylstyrene, o-, m-, or p-ethylstyrene; and aromatic vinyl compounds other than isopropenyl aromatic compounds (I) such as 1,1-diphenylethylene. From the viewpoints of the melt fluidity and productivity of the methacrylic copolymer (A) and the like, styrene (St) and the like are preferable.

[0031] The methacrylic copolymer (A) may contain one or more ring structure units (UR) as one or more other units (UO). Examples of the ring structure unit (UR) include acid anhydride units, maleimide units, and lactone ring units. Examples of other monomers (O) that can introduce a ring structure into the main chain by radical polymerization reaction include acid anhydrides such as maleic anhydride (Mah) and itaconic anhydride; N-alkyl maleimides such as N-methyl maleimide, N-ethyl maleimide, N-butyl maleimide, and N-cyclohexyl maleimide (ChMI); N-aryl maleimides such as N-phenyl maleimide, N-methylphenyl maleimide, and N-chlorophenyl maleimide; and cycloolefins such as norbornene, ethylidene norbornene, dicyclopentadiene, and tetracyclododecene. Among them, maleic anhydride (Mah), N-cyclohexyl maleimide (ChMI), and N-phenyl maleimide are preferred.

[0032] The content of other units (UO) in the methacrylic copolymer (A) (the total amount in the case of multiple types unless otherwise specified) is 0 to 30% by mass. The upper limit is preferably 25% by mass, more preferably 20% by mass, particularly preferably 15% by mass, and most preferably 10% by mass.

[0033] The weight average molecular weight (Mw) of the methacrylic copolymer (A) is not particularly limited and is preferably 40,000 to 400,000. The lower limit is more preferably 50,000, particularly preferably 60,000, and most preferably 70,000. The upper limit is more preferably 300,000, particularly preferably 200,000, and most preferably 100,000. When the Mw of the methacrylic copolymer (A) is at least the above lower limit, it can have excellent mechanical properties, and when it is at most the above upper limit, it can have excellent melt fluidity and moldability. In this specification, unless otherwise specified, the "weight average molecular weight (Mw)" is the weight average molecular weight in terms of standard polystyrene (PSt) determined by gel permeation chromatography (GPC) analysis using a differential refractive index detector.

[0034] The glass transition temperature (Tg) of the methacrylic copolymer (A) is preferably 120°C or higher. The lower limit is more preferably 123°C, still more preferably 125°C, particularly preferably 128°C, and most preferably 130°C. The upper limit is not particularly limited and is, for example, 150°C. The higher the Tg, the higher the heat resistance of the methacrylic copolymer (A), which is preferable. A molded article containing a methacrylic copolymer (A) with a high Tg is less likely to undergo deformation and / or shrinkage due to heat, which is preferable. In this specification, the "glass transition temperature (Tg)" can be measured by the method described in the section [Examples] below in accordance with JIS K7121.

[0035] As described above, the thermoplastic resin composition of the present disclosure contains one or more organic disulfide compounds (C). The addition timing of the organic disulfide compound (C) is not particularly limited. The thermoplastic resin composition of the present disclosure can preferably be produced using an organic disulfide compound-added methacrylic copolymer (AC) containing a methacrylic copolymer (A) and an organic disulfide compound (C).

[0036] The organic disulfide compound-added methacrylic copolymer (AC) can be excellent in thermal decomposition resistance. The thermal decomposition resistance can be indicated by, for example, the 1% thermogravimetric reduction temperature measured by performing thermogravimetric analysis (TGA) in an inert gas atmosphere. The 1% thermogravimetric reduction temperature of the organic disulfide compound-added methacrylic copolymer (AC) is preferably 270°C or higher. The lower limit can be more preferably 275°C, particularly preferably 280°C, and most preferably 285°C. The upper limit is not particularly limited and is, for example, 360°C or 350°C. The 1% thermogravimetric reduction temperature can be measured using a thermogravimetric measurement device and is the temperature at which the weight loss rate becomes 1% with respect to 100% of the weight before heating. For example, under a nitrogen atmosphere, at a heating rate of 10°C / min, thermogravimetric analysis (TGA) is performed under the condition of heating from room temperature (20 - 25°C) to 500°C to obtain a TG curve, and the 1% thermogravimetric reduction temperature can be determined from this TG curve.

[0037] The methacrylic copolymer (AC) added with an organic disulfide compound can be excellent in heat resistance and rigidity even under load. The heat distortion temperature (HDT) measured in accordance with JIS K7191A method of a test piece made of the methacrylic copolymer (A) with a length of 80 mm, a width of 10 mm, and a thickness of 4 mm is preferably 110 °C or higher. The lower limit value is more preferably 112 °C, particularly preferably 115 °C. The upper limit value is not particularly limited, and is, for example, 150 °C, 145 °C, or 140 °C.

[0038] The methacrylic copolymer (AC) added with an organic disulfide compound can be excellent in rigidity. The flexural modulus measured in accordance with JIS K7171 of a test piece made of the methacrylic copolymer (A) with a length of 80 mm, a width of 10 mm, and a thickness of 4 mm is preferably 3200 MPa or higher. The lower limit value is more preferably 3300 MPa, particularly preferably 3500 MPa. The upper limit value is not particularly limited, and is, for example, 5000 MPa or 4500 MPa.

[0039] (Thermoplastic resin (B)) The content of the thermoplastic resin (B) in the thermoplastic resin composition of the present disclosure (the total amount in the case of a plurality of types unless otherwise specified) is 99 to 1% by mass. The lower limit value is preferably 5% by mass, more preferably 10% by mass, particularly preferably 15% by mass, and most preferably 20% by mass. The upper limit value is preferably 95% by mass, more preferably 90% by mass, particularly preferably 85% by mass, and most preferably 80% by mass. The thermoplastic resin composition of the present disclosure can retain the physical properties inherent to the thermoplastic resin (B) if the content of the thermoplastic resin (B) is equal to or higher than the above lower limit value, and can be excellent in heat resistance if it is equal to or lower than the above upper limit value.

[0040] The thermoplastic resin (B) has a heat distortion temperature (HDT) measured in accordance with JIS K7191A method of 60 to 150 °C for a test piece with a length of 80 mm, a width of 10 mm, and a thickness of 4 mm. The lower limit is preferably 65 °C, more preferably 70 °C, particularly preferably 75 °C, and most preferably 80 °C. The upper limit can be 145 °C, 140 °C, 135 °C, or 130 °C.

[0041] The type of the thermoplastic resin (B) is not particularly limited, and examples thereof include (meth)acrylic resins other than the above-mentioned methacrylic copolymer (A), olefin resins, styrene resins, vinyl resins, polyesters, polyamides, polycarbonates, polyethers, polyphenylene ethers (also referred to as polyphenylene oxides), or modified products thereof, polysulfones, polyethersulfones, polyetherimides, polyamideimides, fluorine-containing resins (also referred to as fluorine-based resins), cellulose-based polymers, and multilayer-structured polymer particles.

[0042] Examples of the (meth)acrylic resin include homopolymers or copolymers containing (meth)acrylic acid units or (meth)acrylic acid ester units; modified products thereof, etc. The (meth)acrylic resin can contain one or more units other than (meth)acrylic acid units, (meth)acrylic acid ester units, and derivative units derived from these monomer units. As the thermoplastic resin (B), a (meth)acrylic resin containing methyl methacrylate units and one or more isopropenyl aromatic compound units (UI) and having a content outside the definition of the methacrylic copolymer (A) may be used. Specific examples of the (meth)acrylic resin as the thermoplastic resin (B) include polymethyl methacrylate (PMMA), methyl methacrylate-(meth)acrylic acid copolymer, methyl methacrylate-alkyl acrylate copolymer, and methyl methacrylate-styrene copolymer (MS resin).

[0043] As the (meth)acrylic resin as the thermoplastic resin (B), a homopolymer or copolymer containing (meth)acrylate ester units is preferable, and a homopolymer or copolymer containing methyl methacrylate (MMA) units is preferable. As the (meth)acrylic resin containing methyl methacrylate (MMA) units as the thermoplastic resin (B), a methacrylic homopolymer or copolymer containing methyl methacrylate units, not containing isopropenyl aromatic compound units (UI), and optionally containing other units (UO); a methacrylic copolymer containing methyl methacrylate units and one or more isopropenyl aromatic compound units (UI), wherein the content of the one or more isopropenyl aromatic compound units (UI) is less than 1% by mass, and optionally containing one or more other units (UO); a methacrylic copolymer containing methyl methacrylate units and one or more isopropenyl aromatic compound units (UI), wherein the content of methyl methacrylate units is less than 40% by mass, the content of the one or more isopropenyl aromatic compound units (UI) is 1 to 40% by mass, and optionally containing one or more other units (UO); combinations thereof may be mentioned.

[0044] The olefin resin is a homopolymer or copolymer containing one or more α-olefin units and optionally containing one or more other monomer units. Examples of the α-olefin include ethylene, propylene, butene, hexene, octene, nonene, decene, dodecene and the like. Examples of the form of the copolymer include random copolymer, block copolymer, graft copolymer and the like. Examples of other monomers copolymerizable with the α-olefin include non-conjugated dienes such as 1,4-hexadiene, dicyclopentadiene, 5-ethylidene-2-norbornene and 2,5-norbornadiene; conjugated dienes such as butadiene, isoprene and piperylene; α,β-unsaturated carboxylic acids or their derivatives such as (meth)acrylic acid, their acid anhydrides and (meth)acrylic acid alkyl esters; (meth)acrylonitrile; aromatic vinyl compounds or their derivatives such as styrene and α-methylstyrene; vinyl esters or their derivatives such as vinyl acetate; vinyl ethers or their derivatives such as vinyl methyl ether and the like. The degree of polymerization, presence or absence of side chains or branched chains, degree of branching, and ratio of each unit of the olefin resin are not particularly limited.

[0045] Specific examples of the olefin resin include polyethylene such as high-density polyethylene, medium-density polyethylene, low-density polyethylene, and linear low-density polyethylene; polypropylene; polybutene; polybutylene; methylpentene resin; ethylene-α-olefin copolymers such as ethylene-propylene copolymer and ethylene-1-butene copolymer; ethylene-propylene-diene copolymer; ethylene-vinyl ester copolymers such as ethylene-vinyl acetate copolymer; ethylene-acrylic acid copolymer; ethylene-acrylic acid ester copolymers such as ethylene-ethyl acrylate copolymer; ionomers and the like. Polyethylene; polypropylene; ethylene-α-olefin copolymers such as ethylene-propylene copolymer and ethylene-1-butene copolymer are preferred.

[0046] The styrene resin is a homopolymer or copolymer containing one or more styrene monomer units and may contain one or more other monomer units. Examples of the styrene monomer include styrene, α-methylstyrene, vinyltoluene, t-butylstyrene, and chloromethylstyrene. Examples of the copolymer form include random copolymer, block copolymer, and graft copolymer. Other monomers copolymerizable with the styrene monomer include acrylic monomers; acid anhydrides or their derivatives; conjugated dienes; α-olefins and the like. Examples of the acrylic monomer include (meth)acrylic acid; (meth)acrylic acid esters such as (meth)methyl acrylate; (meth)acrylonitrile and the like. Examples of the acid anhydride or its derivative include maleic anhydride, N-methylmaleimide, and N-phenylmaleimide. Examples of the conjugated diene include butadiene. Examples of the α-olefin include ethylene and propylene. The styrene resin may be a hydrogenated product of a copolymer containing styrene monomer units and conjugated diene units and / or α-olefin units. The styrene resin may be a copolymer obtained by polymerizing the above styrene monomer and the above acrylic monomer with a rubber component such as butadiene rubber, acrylic rubber, chlorinated polyethylene, ethylene-propylene-diene rubber, and ethylene-vinyl acetate copolymer, or a hydrogenated product thereof. The degree of polymerization, presence or absence of side chains or branched chains, branching degree, ratio of each unit, etc. of the styrene resin are not particularly limited.

[0047] Specific examples of the styrene resin include polystyrene, high-impact polystyrene, styrene-(meth)acrylic acid copolymer, acrylonitrile-styrene copolymer (AS resin), styrene-maleic anhydride copolymer, styrene-(meth)methyl acrylate copolymer, styrene-acrylonitrile-ethylene copolymer, styrene-acrylonitrile-butadiene copolymer (ABS resin) or its hydrogenated product, acrylonitrile-ethylene-propylene-diene-styrene copolymer (AES resin), acrylonitrile-acrylic rubber-styrene copolymer (AAS resin), acrylonitrile-chlorinated ethylene-styrene copolymer (ACS resin), and methyl methacrylate-butadiene-styrene copolymer (MBS resin), etc.

[0048] Examples of the vinyl resin include polyvinyl chloride, chlorinated polyvinyl chloride, polyvinyl acetate, polyvinyl alcohol, polyvinyl acetal, polyvinyl ether, polyvinyl ketone, polyvinyl pyrrolidone, and vinyl chloride-vinyl acetate copolymer, etc.

[0049] Polyester is a polymer having an ester bond in the main chain and is usually obtained by polycondensation of a dicarboxylic acid or its derivative and a dihydric alcohol, polycondensation of a hydroxycarboxylic acid, or ring-opening polymerization of a cyclic ester. Examples of polyester include polyalkylene terephthalates such as polyethylene terephthalate and polybutylene terephthalate; copolyesters containing alkylene terephthalate units and other units such as isophthalic acid, bisphenol A, and cyclohexanedimethanol; aromatic polyesters such as polyarylate obtained by esterification of an aromatic diol such as bisphenol A and an aromatic dicarboxylic acid such as terephthalic acid and isophthalic acid; liquid crystalline polyester; polyester elastomer and the like. Polyalkylene terephthalates such as polyethylene terephthalate and polybutylene terephthalate; aromatic polyesters; liquid crystalline polyester; polyester elastomer and the like are preferred.

[0050] Polyamide is a polymer having an amide bond in the main chain and is usually obtained by polycondensation of a dicarboxylic acid and a diamine, or ring-opening polymerization of a cyclic lactam. Examples of polyamide include aliphatic polyamide, aromatic polyamide, liquid crystalline polyamide, liquid crystalline copolyesteramide, and polyamide elastomer and the like. Examples of aliphatic polyamide include polyamide 6, polyamide 12, polyamide 11, polyamide 46, polyamide 66, polyamide 610, polyamide 612, and copolyamides containing the constituent units of these polyamides. Aliphatic polyamides such as polyamide 6, polyamide 66, polyamide 11, and polyamide 12; aromatic polyamide; liquid crystalline copolyesteramide; polyamide elastomer and the like are preferred.

[0051] Polycarbonate is a polymer having carbonate bonds in the main chain and is usually obtained by polycondensation of a dihydroxy compound and phosgene or by transesterification of a dihydroxy compound and a carbonate ester. The polycarbonate may be any of aliphatic polycarbonate, alicyclic polycarbonate, and aromatic polycarbonate. Aromatic polycarbonate is preferred, and bisphenol-type polycarbonate such as bisphenol A type polycarbonate is particularly preferred.

[0052] Polyether is a polymer having ether bonds in the main chain and is usually obtained by ring-opening polymerization of a cyclic ether or by self-condensation of a glycol. Examples of polyether include polyethylene oxide, polypropylene oxide, and polytetramethylene oxide.

[0053] Examples of the fluorine-containing resin (fluororesin) include a homopolymer or copolymer containing one or more fluorine atom-containing monomer units. Examples of the fluorine atom-containing monomer include tetrafluoroethylene, chlorotrifluoroethylene, hexafluoropropylene, perfluoroalkyl vinyl ether, vinylidene fluoride, and vinyl fluoride. Specific examples of the fluorine-containing resin include polytetrafluoroethylene, tetrafluoroethylene-hexafluoropropylene copolymer, ethylene-tetrafluoroethylene copolymer, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, ethylene-chlorotrifluoroethylene copolymer, polychlorotrifluoroethylene, polyvinylidene fluoride, and polyvinyl fluoride.

[0054] Examples of the cellulose-based polymer include cellulose acetate. Examples of the multilayer structure polymer particles include acrylic multilayer structure polymer particles having a core-shell structure of 2 to 4 layers.

[0055] As the thermoplastic resin (B), from the viewpoints of compatibility with the methacrylic resin (A) and the transparency of the resulting thermoplastic resin composition, methacrylic resins such as polymethyl methacrylate (PMMA), methyl methacrylate-alkyl acrylate copolymer, and methyl methacrylate-styrene copolymer (MS resin); styrenic resins compatible with the methacrylic resin (A) such as methyl methacrylate-styrene copolymer (MS resin), acrylonitrile-styrene copolymer (AS resin), and styrene-maleic anhydride copolymer; polyvinyl chloride; polyvinylidene fluoride; phenoxy resin; combinations thereof, etc. are preferred.

[0056] As the thermoplastic resin (B), even if the compatibility or miscibility with the methacrylic resin (A) is not good, a thermoplastic resin capable of exhibiting excellent properties by blending with the methacrylic resin (A) can be preferably used. Examples of such thermoplastic resins include styrenic resins immiscible with the methacrylic resin (A), polyamides, polyesters, polycarbonates, and fluorine-containing resins (fluororesins).

[0057] As described above, an appropriate amount of the organic disulfide compound (C) can also contribute to the thermal stabilization of the thermoplastic resin (B). For example, when the thermoplastic resin (B) contains monomer units in which thermal decomposition proceeds by a radical chain mechanism such as a depolymerization reaction and a radical transfer reaction accompanied by β-scission, the presence of an appropriate amount of the organic disulfide compound (C) effectively suppresses the thermal deterioration and thermal decomposition of the thermoplastic resin (B), and effectively suppresses the deterioration of physical properties such as the heat resistance and rigidity of the resin composition. Examples of the depolymerization reaction type thermoplastic resin (B) include methacrylic resins, styrenic resins, and polyethers. Examples of the radical transfer reaction type thermoplastic resin (B) accompanied by β-scission include olefinic resins.

[0058] (Other polymers) The thermoplastic resin composition of the present disclosure can contain one or more other polymers as long as the effects of the present disclosure are not impaired. Examples of other polymers include thermosetting resins such as phenolic resins, melamine resins, silicone resins, and epoxy resins; polyurethane and chlorinated polyurethane resins; silicone-modified resins; acrylic rubbers, silicone rubbers; acrylic thermoplastic elastomers such as acrylic block copolymers; styrenic thermoplastic elastomers such as SEPS, SEBS, and SIS; and olefin rubbers such as IR, EPR, and EPDM.

[0059] The total content of the methacrylic copolymer (A) and the thermoplastic resin (B) in the thermoplastic resin composition of the present disclosure is preferably 90 to 100% by mass. The lower limit is more preferably 95% by mass. The amount of other polymers (in the case of multiple types, the total amount unless otherwise specified) in the thermoplastic resin composition of the present disclosure is preferably 10 to 0% by mass. The upper limit is more preferably 5% by mass.

[0060] (Filler) The thermoplastic resin composition of the present disclosure can contain one or more fillers as additives as needed, as long as the effects of the present disclosure are not impaired. Examples of fillers include inorganic fine particles containing metal oxides such as silicon oxide (silica) and titanium oxide, metal carbonates such as calcium carbonate and magnesium carbonate, metal sulfates such as barium sulfate, carbon black, talc, clay, or combinations thereof; organic fine particles such as polysiloxane-based crosslinked polymer fine particles; and combinations thereof. The filler can function as a light diffusing agent or a matting agent. From the perspective of transparency, it is preferable that the content of the filler in the thermoplastic resin composition of the present disclosure is low, preferably 0 to 3% by mass. The upper limit is more preferably 1.5% by mass, particularly preferably 1% by mass, and most preferably 0.5% by mass. The thermoplastic resin composition of the present disclosure preferably does not contain particles other than the multilayered structure polymer particles as the thermoplastic resin (B).

[0061] (Other additives other than the above) The thermoplastic resin composition of the present disclosure can contain, as additives, an organic disulfide compound (C) and one or more other additives other than fillers, as long as the effects of the present invention are not impaired. Examples of the other additives include antioxidants, heat deterioration inhibitors, ultraviolet absorbers, light stabilizers, lubricants, mold release agents, polymer processing aids, antistatic agents, flame retardants, colorants (dyes, pigments, organic dyes, etc.), and phosphors. The content of the organic disulfide compound (C) and other additives other than fillers in the thermoplastic resin composition of the present disclosure (total amount in the case of multiple types unless otherwise specified) is preferably 0 to 7% by mass from the viewpoint of suppressing appearance defects of the molded article. The upper limit is more preferably 5% by mass, particularly preferably 4% by mass. The addition timing of other polymers and additives other than the organic disulfide compound (C) that can be contained in the thermoplastic resin composition of the present disclosure is not particularly limited, and is optional, similar to the addition timing of the organic disulfide compound (C).

[0062] [Method for Producing Thermoplastic Resin Composition] The method for producing the thermoplastic resin composition of the present disclosure is not particularly limited. The method for producing the thermoplastic resin composition of the present disclosure can have, for example, a step of melt-kneading one or more methacrylic copolymers (A), one or more thermoplastic resins (B), and, if necessary, one or more other polymers. In the method for producing the thermoplastic resin composition of the present disclosure, one or more additives including the organic disulfide compound (C) can be added at any timing.

[0063] The method for producing the thermoplastic resin composition according to one embodiment of the present invention is a step (S1) of producing an organic disulfide compound-added methacrylic copolymer (AC) containing a methacrylic copolymer (A) and an organic disulfide compound (C); and a step (S2) of melt-kneading 1 to 99% by mass of the organic disulfide compound-added methacrylic copolymer (AC) and 99 to 1% by mass of the thermoplastic resin (B).

[0064] (Step (S1)) Step (S1) includes: a step (S1-1) of preparing a polymerization raw material containing methyl methacrylate (MMA) and one or more isopropenyl aromatic compounds (I) as raw material monomers and further containing a polymerization initiator; a step (S1-2) of polymerizing the above polymerization raw material to obtain a resin solution containing a methacrylic copolymer (A); and a step (S1-3) of volatilizing and removing at least a part of the raw material monomers present in the above resin solution in one or more steps to obtain a methacrylic copolymer (A). In the method for producing the thermoplastic resin composition of the present embodiment, one or more organic disulfide compounds (C) can be added to at least one of the above polymerization raw material, the above resin solution obtained after the completion of step (S1-2), and the above resin solution during the implementation of step (S1-3).

[0065] <Step (S1-1)> Prepare a polymerization raw material containing the above plurality of types of raw material monomers and a polymerization initiator. As the polymerization initiator, one or more known radical polymerization initiators can be used. Specific examples include t-hexyl peroxyisopropyl monocarbonate, t-hexyl peroxy 2-ethylhexanoate, 1,1,3,3-tetramethylbutyl peroxy 2-ethylhexanoate, t-butyl peroxypivalate, t-hexyl peroxypivalate, t-butyl peroxyneodecanoate, t-hexyl peroxyneodecanoate, 1,1,3,3-tetramethylbutyl peroxyneodecanoate, 1,1-bis(t-hexylperoxy)cyclohexane, benzoyl peroxide, 3,5,5-trimethylhexanoyl peroxide, lauroyl peroxide, 2,2'-azobis(2-methylpropionitrile) (AIBN), 2,2'-azobis(2-methylbutyronitrile), and dimethyl 2,2'-azobis(2-methylpropionate), etc. Among them, 2,2'-azobis(2-methylpropionitrile) (AIBN), t-hexyl peroxy 2-ethylhexanoate, 1,1-bis(t-hexylperoxy)cyclohexane, and dimethyl 2,2'-azobis(2-methylpropionate) are preferred.

[0066] The polymerization raw material can contain one or more chain transfer agents as needed. The chain transfer agent can be used for purposes such as adjusting the molecular weight of the methacrylic copolymer (A). Examples of the chain transfer agent include alkyl mercaptans such as n-octyl mercaptan (n-OM), n-dodecyl mercaptan, t-dodecyl mercaptan, 1,4-butanedithiol, 1,6-hexanedithiol, ethylene glycol bisthiopropionate, butanediol bisthioglycolate, butanediol bisthiopropionate, hexanediol bisthioglycolate, hexanediol bisthiopropionate, trimethylolpropane tris-(β-thiopropionate), and pentaerythritol tetrakisthiopropionate; α-methylstyrene (αMSt) dimer; terpinolene, etc. Among them, monofunctional alkyl mercaptans such as n-octyl mercaptan (n-OM) and n-dodecyl mercaptan are preferred. The amount of the chain transfer agent used (in the case of multiple types, the total amount unless otherwise specified) is not particularly limited, and is preferably 0 to 1 part by mass with respect to 100 parts by mass of the total amount of the plurality of raw material monomers. The upper limit value is more preferably 0.5 part by mass, particularly preferably 0.4 part by mass, and most preferably 0.3 part by mass.

[0067] The polymerization raw materials can contain one or more additives other than the above, if necessary. The polymerization raw materials can be prepared by mixing a plurality of raw material monomers, one or more polymerization initiators, one or more chain transfer agents if necessary, and one or more additives if necessary, in an inert gas atmosphere such as nitrogen gas or in the presence of oxygen. They can be mixed all at once or dividedly, and the compounding procedure in the case of divided mixing is not particularly limited. The water content in the polymerization raw materials is preferably 1000 ppm or less, more preferably 700 ppm or less, and particularly preferably 280 ppm or less. The polymerization raw materials can be dehydrated by a known method if necessary. The polymerization raw materials preferably have the dissolved oxygen amount reduced to 10 ppm or less by nitrogen purging or the like. The dissolved oxygen amount is more preferably 5 ppm or less, particularly preferably 4 ppm or less, and most preferably 3 ppm or less.

[0068] <Step (S1-2)> The polymerization can be carried out by a known method, and the bulk polymerization method is preferred. For example, a continuous bulk polymerization method is preferred in which the polymerization raw materials prepared in step (S1-1) are continuously supplied to a tank-type reactor, bulk polymerization is carried out in the tank-type reactor to obtain a resin solution containing the methacrylic copolymer (A), and the obtained resin solution is continuously withdrawn from the tank-type reactor. The polymerization is preferably carried out in an atmosphere of an inert gas such as nitrogen gas. The polymerization temperature is not particularly limited, and is preferably 110 to 160 °C, more preferably 120 to 155 °C. The average residence time in the tank-type reactor is not particularly limited, and is preferably 1.5 to 6 hours, more preferably 2 to 5.5 hours, and particularly preferably 2.5 to 5 hours. The average concentration of the radical polymerization initiator present in the liquid in the trough reactor is not particularly limited, and is preferably 1.0×10 -6 ~2.0×10 -5 mol / L. The polymerization conversion rate is preferably 20 to 60%. The lower limit is more preferably 25%. The upper limit is preferably 55%, more preferably 50%.

[0069] <Step (S1-3)> At least a part of the unreacted raw material monomer present in the resin solution is volatilized and removed in one or a plurality of steps. Examples of the volatilization and removal method include an adiabatic flash evaporation method, an equilibrium flash evaporation method, and a combination thereof, and an adiabatic flash evaporation method or the like is preferable. The volatilization and removal of the unreacted raw material monomer present in the resin solution can be carried out by a known method using a heat exchanger, an extruder with a vent, and a combination thereof, and the combined use of a heat exchanger and an extruder with a vent is preferable.

[0070] The heating temperature by the heat exchanger (also referred to as the set temperature of the heat exchanger or the heat exchanger temperature) is not particularly limited, and is preferably 180 to 280°C. The lower limit is more preferably 190°C, particularly preferably 200°C. The upper limit is more preferably 270°C, particularly preferably 260°C, and most preferably 250°C. Examples of the extruder include a single-screw extruder, a twin-screw extruder, and a multi-screw extruder. The extruder has a resin inlet into which the resin solution is introduced, a cylinder containing a screw, and a die including a resin outlet for discharging the methacrylic copolymer (A) obtained after the step (S1-3), and can have an additive supply port as necessary. The number of vents included in the extruder with a vent is one or more, and preferably a plurality. The molten resin temperature in the die (also referred to as the die resin temperature) is not particularly limited, and is preferably 230 to 260°C. The lower limit is more preferably 235°C, particularly preferably 240°C. The upper limit is more preferably 255°C, particularly preferably 250°C.

[0071] If the heating temperature by the heat exchanger and the molten resin temperature in the die are within the above ranges, thermal decomposition of the methacrylic copolymer (A) is suppressed, and a methacrylic copolymer (A) excellent in heat resistance and thermal decomposition resistance (thermal stability) can be produced. Further, a methacrylic copolymer (A) having a uniform composition such as the content of the isopropenyl aromatic compound unit (UI) can be stably produced, and a methacrylic copolymer (A) having good heat resistance and mechanical properties such as rigidity and surface hardness can be stably produced. The unreacted raw material monomers removed from the resin solution may be recovered and reused as raw material monomers.

[0072] In the production method of this embodiment, at least one of the polymerization raw material, the resin solution obtained after the completion of step (S1-2), and the resin solution during the implementation of step (S1-3) is added with one or more organic disulfide compounds (C) so that an appropriate amount of one or more organic disulfide compounds (C) is present in the organic disulfide compound-added methacrylic copolymer (AC) obtained after step (S1). It is preferable to add one or more organic disulfide compounds (C) to at least the polymerization raw material among the polymerization raw material, the resin solution obtained after the completion of step (S1-2), and the resin solution during the implementation of step (S1-3).

[0073] The addition amount of the organic disulfide compound (C) to the polymerization raw material (the total amount in the case of a plurality of types unless otherwise specified) is preferably 10 to 2000 ppm. The lower limit value is more preferably 20 ppm, further preferably 30 ppm, further preferably 50 ppm, further preferably 80 ppm, particularly preferably 100 ppm, and most preferably 200 ppm. The upper limit value is more preferably 1500 ppm, particularly preferably 1200 ppm, and most preferably 1000 ppm.

[0074] The content (in the case of multiple types, the total amount unless otherwise specified) of the organic disulfide compound (C) in the methacrylic copolymer (AC) added with the organic disulfide compound obtained after the step (S1) is preferably 10 to 2000 ppm. More preferably 20 ppm, even more preferably 30 ppm, even more preferably 50 ppm, even more preferably 70 ppm, particularly preferably 80 ppm, and most preferably 100 ppm. The upper limit value is more preferably 1500 ppm, particularly preferably 1200 ppm, and most preferably 1000 ppm. The methacrylic copolymer (AC) added with the organic disulfide compound contains a methacrylic copolymer (A) containing isopropenyl aromatic compound units (UI) and an appropriate amount of the organic disulfide compound (C), and can be excellent in heat resistance, thermal decomposition resistance (thermal stability), and mechanical properties such as rigidity and surface hardness.

[0075] Generally, a methacrylic copolymer containing isopropenyl aromatic compound units such as MMA units and αMSt units tends to have a relatively low thermal decomposition temperature. Therefore, when this copolymer is heated and melted during resin production and molding processing, etc., the copolymer may thermally decompose, increasing the amount of residual monomer in the resin and reducing the heat resistance. Also, when the residence time in the heated and melted state is long during resin production and molding processing, etc., appearance defects such as foaming and generation of gel-like foreign substances may occur due to the thermal decomposition of the methacrylic copolymer.

[0076] In the production method of this embodiment, in the step (S1), the thermal decomposition of the methacrylic copolymer (A) is effectively suppressed by the presence of an appropriate amount of the organic disulfide compound (C). As a result, a methacrylic copolymer (A) with a small amount of residual monomer and excellent heat resistance and thermal decomposition resistance (thermal stability) can be stably produced. In addition, in step (S1), due to the presence of an appropriate amount of the organic disulfide compound (C), the copolymerization of the isopropenyl aromatic compound (I) can be relatively easily controlled, and a methacrylic copolymer (A) with a uniform composition such as the content of the isopropenyl aromatic compound unit (UI) can be stably produced. A methacrylic copolymer (A) having good heat resistance and mechanical properties such as rigidity and surface hardness can be stably produced. In step (S1), even if the residence time in the heat-melted state becomes long, appearance defects such as foaming due to thermal decomposition of the methacrylic copolymer (A) and generation of gel-like foreign matters are suppressed.

[0077] Even when the organic disulfide compound-added methacrylic copolymer (AC) is heat-melted during step (S2) and subsequent molding processes, etc., the thermal degradation and thermal decomposition of the methacrylic copolymer (A) and the thermoplastic resin (B) can be effectively suppressed due to the presence of an appropriate amount of the organic disulfide compound (C).

[0078] (Step (S2)) The melt-kneading can be carried out in one step or multiple steps, and the blending procedure of multiple types of copolymers is arbitrary. The melt-kneading can be carried out using a known mixing device or kneading device such as an extruder (preferably a twin-screw extruder), a kneader extruder, a mixing roll, and a Banbury mixer. The thermoplastic resin composition of the present disclosure can be processed into a form suitable as a molding material such as pellets and powders by a known method.

[0079] As described above, according to the present disclosure, a thermoplastic resin composition containing a methacrylic copolymer containing a methyl methacrylate unit and one or more isopropenyl aromatic compound units, having good heat resistance, rigidity, and thermal decomposition resistance, and a method for producing the same can be provided.

[0080] [Molded article] The molded article of the present disclosure includes a layer or member made of the above-described thermoplastic resin composition of the present disclosure, and may be entirely a layer or member made of the above-described thermoplastic resin composition of the present disclosure. The form of the molded article is not particularly limited, and examples include flat articles having a single-layer structure or a laminated structure such as films, sheets, and plates; fibers, pipes, tubes, rods; particles; any three-dimensional structure, etc. The molded article may be a laminate or composite including a layer or member made of the thermoplastic resin composition of the present disclosure and a layer or member made of other resins or various materials other than resins. For the molded article obtained by a known molding method, surface treatments such as printing, painting, plating, vapor deposition, and sputtering; shape processing such as bending, folding, and cutting (also referred to as secondary molding), etc. may be carried out as necessary. Generally, for thin film molded articles, depending on the thickness, the terms "film", "sheet", or "plate" are used, but there is no clear definition for these, and there is no clear distinction between them.

[0081] The molding method is not particularly limited, and examples include melt molding methods such as extrusion molding, injection molding, inflation molding, blow molding, and calender molding; compression molding (also referred to as press molding); vacuum molding and pressure air molding; solution casting method (also referred to as solution cast method), etc. Among the above, the melt molding method is preferred. The melt molding temperature is not particularly limited, and is preferably 180 to 280 °C, more preferably 200 to 260 °C. Since the thermoplastic resin composition of the present disclosure containing one or more organic disulfide compounds (C) is excellent in heat decomposition resistance (thermal stability), even when heated at a relatively high temperature, thermal degradation and thermal decomposition are suppressed, and a molded article with good appearance and high quality can be provided.

[0082] [Applications] The thermoplastic resin composition of the present disclosure and the molded article containing the same can be used for any application. Applications include furniture, household goods, storage and stockpiling goods, building materials such as walls and roofs, toys and play equipment, gaming applications such as pachinko machine panels, medical and welfare goods, OA equipment, AV equipment, battery and electrical equipment, lighting equipment, and vehicle applications, etc. The thermoplastic resin composition of the present disclosure and the molded article containing the same are suitable for optical applications; vehicle applications such as body parts and interior and exterior members of transportation equipment such as automobiles, ships, and airplanes; electrical and electronic applications, etc.

[0083] As optical applications, for example, display applications such as liquid crystal displays, plasma displays, organic electroluminescence (EL) displays, and touch panel displays combining touch panels and various displays can be mentioned. Examples of optical members for displays include display substrates, display front panels, polarizer protection films, retardation plates, optical compensation films (such as viewing angle control films), transparent conductive substrates of touch panels, light guide plates, and lenses (arrays) such as head-up displays and prisms. In this specification, unless otherwise specified, "lens (array)" is a general term for lenses and lens arrays. As other optical members, optical members for solar cells (such as transparent substrates, back films, and front films); optical members used in fields such as optical communication, optical switching, and optical measurement (such as waveguides, lenses (arrays), optical fibers, and coating materials for optical fibers); optical members for light-emitting elements such as light-emitting diodes (LEDs) (such as lenses and lens covers) and the like can be mentioned.

[0084] As vehicle applications, automotive interior members such as side visors, rear visors, head wings, headlight covers, parts around the instrument panel, air conditioner outlets, dashboards, and console boxes; automotive exterior members such as mirror housings, spoilers, pillar garnishes, wheel caps, rear lamp housings, bumpers, front grilles, rear grilles, and number plate garnishes and the like can be mentioned.

[0085] As electrical and electronic applications, electronic devices with displays such as personal computers, televisions, car navigation systems, mobile phones, tablet terminals, electronic paper, electronic dictionaries, electronic notebooks, electronic desktop calculators, and game machines; OA devices such as drives and reading devices for recording media, keyboards, numeric keypads, mice, printers, copiers, scanners, and fax machines; cameras and video cameras; audio players such as CD players and MD players, and portable radios; battery packs; home appliances such as dryers, electric kettles, and lighting devices and the like can be mentioned.

Examples

[0086] Examples and comparative examples according to the present invention will be described. [Evaluation Items and Evaluation Methods] The evaluation items and evaluation methods are as follows. (Polymerization Conversion Rate) The polymerization conversion rate was determined by gas chromatography analysis. To the "Gas Chromatograph GC-14A" manufactured by Shimadzu Corporation, "INERTCAP1" (film thickness 0.4 μm, inner diameter 0.25 mmφ, length 60 m) manufactured by GL Sciences Inc. was connected as a column. Analysis was performed under the following conditions, and the polymerization conversion rate was calculated from the obtained data. Injection temperature: 250 °C, Detector temperature: 250 °C, Temperature profile: Hold at 60 °C for 5 minutes → Heat up to 250 °C at a heating rate of 10 °C / min → Hold at 250 °C for 10 minutes.

[0087] (Weight-Average Molecular Weight (Mw)) The weight-average molecular weight (Mw) of the resin was determined by gel permeation chromatography (GPC) analysis. As a measuring device, the GPC device "HLC-8320" manufactured by Tosoh Corporation was used. As a separation column, a series connection of "TSKguardcolum SuperHZ-H", "TSKgel HZM-M", and "TSKgel SuperHZ4000" manufactured by Tosoh Corporation was used. As a detector, a differential refractive index detector (RI detector) was used. 4 mg of the resin to be measured was dissolved in 5 ml of tetrahydrofuran to prepare a sample solution. The temperature of the column oven was set to 40 °C. Tetrahydrofuran was used as the eluent, the eluent flow rate was set to 0.35 ml / min, 20 μl of the sample solution was injected into the apparatus, and the chromatogram was measured. GPC measurements were performed on 10 standard polystyrenes (PSt) within the molecular weight range of 400 to 5,000,000, and a calibration curve showing the relationship between the retention time and the molecular weight was created. Based on this calibration curve, the Mw of the resin to be measured in terms of standard PSt was determined.

[0088] (Glass Transition Temperature (Tg)) The glass transition temperature (Tg) of the resin to be measured was measured using a differential scanning calorimeter ("DSC-50" manufactured by Shimadzu Corporation) in accordance with JIS K7121. 10 mg of the resin to be measured was placed in an aluminum pan and set in the above apparatus. After nitrogen substitution for 30 minutes or more, the temperature was raised from room temperature (20 to 25 °C) to 250 °C at a rate of 20 °C / min in a nitrogen stream of 10 ml / min, held for 5 minutes, and then cooled to room temperature (primary scan). Subsequently, the temperature was raised to 200 °C at a rate of 10 °C / min (secondary scan), and the DSC curve was measured. The midpoint glass transition temperature obtained from the DSC curve obtained in the secondary scan was defined as the glass transition temperature (Tg).

[0089] (Unit composition of methacrylic copolymer) 1 The 1H-NMR spectrum or 13 the 13C-NMR spectrum was measured, and the unit composition of the methacrylic copolymer was determined from the ratio of the integral values of the peaks derived from each unit. The following shows an example of a specific measurement method.

[0090] For methyl methacrylate-α-methylstyrene copolymer (MMA-αMSt copolymer), 1 the 1H-NMR spectrum was measured, the peaks derived from the protons of the methoxy group of the methyl methacrylate (MMA) unit and the peaks derived from the protons of the phenyl group of the α-methylstyrene (αMSt) unit were identified, and the unit composition was determined from the ratio of the integral values of each peak.

[0091] For methyl methacrylate-α-methylstyrene-styrene copolymer (MMA-αMSt-St copolymer), under the conditions of the measurement mode: inverse gated decoupling method, 13 the 13C-NMR spectrum was measured, the peaks derived from the carbon of the carbonyl group of the methyl methacrylate (MMA) unit, the peaks derived from the carbon of the phenyl group of the α-methylstyrene (αMSt) unit, and the peaks derived from the carbon of the phenyl group of the styrene (St) unit were identified, and the unit composition was determined from the ratio of the integral values of each peak.

[0092] Regarding the methyl methacrylate-α-methylstyrene-maleic anhydride copolymer (MMA-αMSt-Mah copolymer), under the conditions of the measurement mode: inverse gated decoupling method, 13 The 13C-NMR spectrum was measured, and the peak derived from the carbon of the carbonyl group of the methyl methacrylate (MMA) unit, the peak derived from the carbon of the phenyl group of the α-methylstyrene (αMSt) unit, and the peak derived from the carbon of the carbonyl group of the maleic anhydride (Mah) unit were identified, and the unit composition was determined from the ratio of the integral values of each peak.

[0093] (Content of the organic disulfide compound (C)) The content of the organic disulfide compound (C) in the organic disulfide compound-added methacrylic copolymer (AC) or the thermoplastic resin composition was measured as follows. After dissolving 2 g of the resin (composition) to be measured in 10 mL of dichloromethane, 30 mL of hexane was added and reprecipitation was carried out. The supernatant obtained after this reprecipitation treatment was separated, and the solvent in this supernatant was removed by distillation under reduced pressure and concentrated. The obtained concentrate was dissolved again in 1 mL of dichloromethane, then 4 mL of hexane was added and reprecipitation was carried out. 25 μL of the supernatant obtained after this reprecipitation treatment was collected on a platinum board as a measurement sample, and after removing dichloromethane, pyrolysis gas chromatography analysis was performed. To the "Gas Chromatograph GC-14A" manufactured by Shimadzu Corporation, "Agilent J&W Series DB-5" (inner diameter: 0.25 mm, film thickness: 0.25 μm, length: 30.0 m) manufactured by Agilent Technologies was connected as a column. Analysis was carried out under the following conditions. Based on the calibration curve obtained from the pyrolysis gas chromatography analysis of standard solutions of multiple organic disulfide compounds with different concentrations, the content of the organic disulfide compound (C) was determined. Vaporization chamber temperature: 260 °C, Column oven temperature: 100 °C, Temperature profile: Heating rate 20 °C / min to 320 °C → Hold at 320 °C for 30 minutes.

[0094] (1% Thermogravimetric weight loss temperature) Using a thermogravimetric analyzer (TGA-50 manufactured by Shimadzu Corporation), in a nitrogen atmosphere, at a heating rate of 10 °C / min, approximately 5 mg of the resin to be measured was heated from room temperature (20 - 25 °C) to 500 °C to obtain a TG curve. The temperature at which the weight loss rate reached 1% with respect to the weight before heating was determined as the 1% thermogravimetric temperature.

[0095] (Melt Flow Rate (MFR)) Using a melt indexer (L225-11 manufactured by Tatsuyama Science & High Technology Co., Ltd.), in accordance with JIS-K7210, the melt flow rate (MFR) of the methacrylic copolymer was measured under the conditions of 230 °C, a load of 3.8 kg, and for 10 minutes.

[0096] (Flexural Modulus) Using an injection molding machine (M-100C manufactured by Meiki Seisakusho Co., Ltd.), test pieces with a length of 80 mm, a width of 10 mm, and a thickness of 4 mm were obtained. The obtained test pieces were conditioned in accordance with JIS K6712-2. The flexural modulus of this test piece was measured in accordance with JIS K7171 using a precision universal testing machine Autograph (AG-IS5kN manufactured by Shimadzu Corporation).

[0097] (Heat Deflection Temperature (HDT)) Using an injection molding machine (M-100C manufactured by Meiki Seisakusho Co., Ltd.), test pieces with a length of 80 mm, a width of 10 mm, and a thickness of 4 mm were obtained. The obtained test pieces were conditioned in accordance with JIS K6712-2. The heat deflection temperature (HDT) of this test piece was measured in accordance with JIS K7191.

[0098] (Total Light Transmittance) Using an injection molding machine (M-100C manufactured by Meiki Seisakusho Co., Ltd.), test pieces with a size of 50 mm square and a thickness of 3 mm were obtained. The total light transmittance of this test piece was measured in accordance with JIS K7361 using a haze meter (HM-150 manufactured by Murakami Color Research Laboratory).

[0099] [Thermoplastic Resin (B)] The thermoplastic resin (B) used is as follows. (B-1) Methacrylic resin: "Parapet G" manufactured by Kuraray Co., Ltd., HDT = 93°C, (B-2) MS resin (methyl methacrylate-styrene copolymer): "Toyo MS MS-600" manufactured by Toyo Styrene Co., Ltd., HDT = 79°C, (B-3) AS resin (acrylonitrile-styrene copolymer): "Denka AS AS-C-800" manufactured by Denka Co., Ltd., HDT = 83°C, (B-4) PVDF (polyvinylidene fluoride): "KYNAR Homopolymer Series KYNAR720" manufactured by Arkema, HDT = 75°C, (B-5) Vinyl chloride resin compound: "Vinica CF60LA" manufactured by Mitsubishi Chemical Corporation, HDT = 65°C, (B-6) Polyamide: "UBE Nylon Polyamide 6 1013B" manufactured by UBE Industries, Ltd., HDT = 60°C, (B-7) Polycarbonate: "SD Polyca 301-22" manufactured by Sumitomo Chemical Polycarbonate Co., Ltd., HDT = 126°C, (B-8) Polybutylene terephthalate: "Duranex 457EV" manufactured by Polyplastics Co., Ltd., HDT = 75°C, (B-9) Polyacetal: "Duracon M90-44" manufactured by Polyplastics Co., Ltd., HDT = 95°C, (B-10) Ethylene-tetrafluoroethylene copolymer (ETFE): "Fluon C-88AXP" manufactured by AGC Inc., HDT = 63°C.

[0100] [Additives] The additives used are as follows. <Organic disulfide compound (C)> (DDS) Di-tert-dodecyl disulfide.

[0101] [Production Example PE1] Production of DDS-added methacrylic copolymer (AC-1) A stirrer and an autoclave equipped with a sampling tube were charged with 60 parts by mass of purified methyl methacrylate (MMA), 31 parts by mass of α-methylstyrene (αMSt), 9 parts by mass of styrene (St), 100 ppm of n-octyl mercaptan (n-OM) as a chain transfer agent, and 300 ppm of di-tert-dodecyl disulfide (DDS), and uniformly mixed. To this, 500 ppm of 2,2'-azobis(2-methylpropionitrile) (AIBN) was added as a polymerization initiator and uniformly mixed to obtain a polymerization raw material. Nitrogen gas was blown into this polymerization raw material to set the dissolved oxygen concentration to 3 ppm.

[0102] Next, a continuous flow tank reactor equipped with a brine cooling condenser was prepared and the inside was purged with nitrogen gas. The above polymerization raw material was continuously supplied to this reactor at a constant flow rate so that the average residence time was 4.0 hours, and bulk polymerization was carried out at a polymerization temperature of 140°C, and a resin solution containing a methacrylic copolymer as a reaction product was continuously discharged from the reactor. The pressure inside the reactor was adjusted by a pressure regulating valve connected to the brine cooling condenser. The polymerization conversion rate was 42%.

[0103] A die having a resin inlet for introducing the resin solution discharged from the above reactor and a resin outlet for discharging the produced resin was prepared. Further, a first vent (also referred to as a rear vent) located relatively close to the resin inlet, a second vent (also referred to as a front vent) located relatively close to the resin outlet, and an additive supply port located between the second vent (front vent) and the resin outlet were provided.

[0104] The resin solution discharged from the above reactor was heated using a heat exchanger and then supplied into the above extruder through a resin inlet. The set temperature of the heat exchanger was 200 °C, and the set temperature of the cylinder of the extruder was 255 °C. Volatile components mainly composed of unreacted monomers were flash-evaporated from the resin solution supplied into the cylinder of the extruder and discharged from the first vent (rear vent). Further, the resin was conveyed in the axial direction of the cylinder by a screw, and the volatile components evaporating during that time were discharged from the second vent (front vent). The obtained strand was cut by a pelletizer. As described above, pellets of the DDS-added methacrylic copolymer (AC-1) were obtained. The unit composition of the copolymer, the content of DDS in the DDS-added methacrylic copolymer (AC-1), and the results of physical property evaluation are shown in Table 1.

[0105] [Production Example PE2] Production of DDS-free methacrylic copolymer (A-1) Pellets of the DDS-free methacrylic copolymer (A-1) were obtained in the same manner as in Production Example PE1, except that the charged composition was changed to be free of di-tert-dodecyl disulfide (DDS). The unit composition of the copolymer and the results of physical property evaluation of the DDS-free methacrylic copolymer (A-1) are shown in Table 1.

[0106] [Production Example PE3] Production of DDS-added methacrylic copolymer (AC-2) Pellets of the DDS-added methacrylic copolymer (AC-2) were obtained in the same manner as in Production Example PE1, except that the charged composition was changed to 80 parts by mass of methyl methacrylate (MMA), 20 parts by mass of α-methylstyrene (αMSt), 400 ppm of n-octyl mercaptan (n-OM), and 500 ppm of di-tert-dodecyl disulfide (DDS), the amount of 2,2'-azobis(2-methylpropionitrile) (AIBN) was changed to 500 ppm, the average residence time was changed to 3.5 hours, and the polymerization temperature was changed to 120 °C. The unit composition of the copolymer, the content of DDS in the DDS-added methacrylic copolymer (AC-2), and the results of physical property evaluation are shown in Table 1.

[0107] [Production Example PE4] Production of DDS-free methacrylic copolymer (A-2) The feed composition was changed to 75 parts by mass of methyl methacrylate (MMA), 25 parts by mass of α-methylstyrene (αMSt), and no addition of di-tert-dodecyl disulfide (DDS). Otherwise, in the same manner as in Production Example PE3, pellets of the DDS-free methacrylic copolymer (A-2) were obtained. The unit composition of the copolymer and the physical property evaluation results of the DDS-free methacrylic copolymer (A-2) are shown in Table 1.

[0108] [Production Example PE5] Production of DDS-added methacrylic copolymer (AC-3) The feed composition was changed to 75 parts by mass of methyl methacrylate (MMA), 15 parts by mass of α-methylstyrene (αMSt), 10 parts by mass of maleic anhydride (Mah), 200 ppm of n-octyl mercaptan (n-OM), and 300 ppm of di-tert-dodecyl disulfide (DDS). The amount of 2,2'-azobis(2-methylpropionitrile) (AIBN) was changed to 300 ppm, and the average residence time was changed to 2.5 hours, and the polymerization temperature was changed to 130 °C. Otherwise, in the same manner as in Production Example PE1, pellets of the DDS-added methacrylic copolymer (AC-3) were obtained. The unit composition of the copolymer, the content of DDS in the DDS-added methacrylic copolymer (AC-3), and the physical property evaluation results are shown in Table 1.

[0109] [Production Example PE6] Production of DDS-free methacrylic copolymer (A-3) The feed composition was changed to 62 parts by mass of methyl methacrylate (MMA), 25 parts by mass of α-methylstyrene (αMSt), 13 parts by mass of maleic anhydride (Mah), and no addition of di-tert-dodecyl disulfide (DDS). Otherwise, in the same manner as in Production Example PE5, pellets of the DDS-free methacrylic copolymer (A-3) were obtained. The unit composition of the copolymer and the physical property evaluation results of the DDS-free methacrylic copolymer (A-3) are shown in Table 1.

[0110]

Table 1

[0111] [Examples 1 to 14, Comparative Examples 1 to 14] In each of Examples 1 to 14 and Comparative Examples 1 to 14, with the formulation compositions shown in Table 2 or Table 3, a DDS-added methacrylic copolymer (AC) or a DDS-free methacrylic copolymer (A) and a thermoplastic resin (B) were blended, and melt-kneaded at 250°C using a twin-screw extruder with L / D = 32.5 and a screw diameter of 62.5 mmφ, and then extruded to obtain a thermoplastic resin composition. Note that L / D is the ratio of the effective length (L) of the screw to the diameter (D) of the screw. In each example, for the sample of the thermoplastic resin (B) alone used in each example and the sample of the thermoplastic resin composition obtained in each example, evaluations were carried out on the total light transmittance (transparency), heat distortion temperature (HDT) (heat resistance), 1% thermal weight loss temperature (thermal stability), or flexural modulus (rigidity). For each evaluation item, judgment was made according to the following criteria. A: The evaluation result of the sample of the thermoplastic resin composition is superior to the evaluation result of the sample of the thermoplastic resin (B) alone. B: The evaluation results of the sample of the thermoplastic resin (B) alone and the sample of the thermoplastic resin composition are equivalent. C: The evaluation result of the sample of the thermoplastic resin composition is inferior to the evaluation result of the sample of the thermoplastic resin (B) alone. The evaluation results are shown in Table 2 and Table 3. In these tables, the conditions not described in the table were taken as common conditions. In the tables, the symbol E indicates an example, and the symbol EC indicates a comparative example.

[0112]

Table 2

[0113]

Table 3

[0114] [Summary of Results] In all of the production examples PE1, PE3, and PE5, the DDS-added methacrylic copolymer (AC) obtained had good heat resistance, thermal decomposition resistance (thermal stability), and rigidity, and all contained an appropriate amount of the organic disulfide compound (C). In Examples 1 to 9, a thermoplastic resin composition was obtained that contained 1 to 99% by mass of a DDS-added methacrylic copolymer (AC) containing a methacrylic copolymer (A) and an organic disulfide compound (C), 99 to 1% by mass of a thermoplastic resin (B) having good compatibility with the methacrylic copolymer (A), and 1 to 1000 ppm of the organic disulfide compound (C). Since all of the thermoplastic resin compositions obtained in these examples contained the DDS-added methacrylic copolymer (AC) having the above properties, they had good heat resistance and thermal stability. Since all of the thermoplastic resin compositions obtained in these examples contained an appropriate amount of the organic disulfide compound (C), thermal degradation of the resin, and the resulting foaming and generation of gel-like foreign substances were effectively suppressed during the production of the thermoplastic resin composition and the molded article. In all of these examples, the compatibility between the methacrylic copolymer (A) and the thermoplastic resin (B) was good, and foaming and the generation of gel-like foreign substances due to thermal degradation of the resin were suppressed, resulting in a thermoplastic resin composition having a total light transmittance of 80% or more and good transparency.

[0115] In Examples 10 to 14, a thermoplastic resin composition was obtained that contained 1 to 99% by mass of a DDS-added methacrylic copolymer (AC) containing a methacrylic copolymer (A) and an organic disulfide compound (C), 99 to 1% by mass of a thermoplastic resin (B) having poor compatibility with the methacrylic resin (A), and 1 to 1000 ppm of the organic disulfide compound (C). Since all of the thermoplastic resin compositions obtained in these examples contained the DDS-added methacrylic copolymer (AC) having the above properties, they had good heat resistance, thermal stability, and rigidity. All of the thermoplastic resin compositions obtained in these examples contained an appropriate amount of the organic disulfide compound (C), thereby effectively suppressing thermal degradation of the resin during the production of the thermoplastic resin composition and the molded article, and the resulting reduction in the molecular weight of the resin and increase in residual monomers, and a thermoplastic resin composition having good rigidity was obtained.

[0116] In the methacrylic copolymers (A) obtained in Production Examples PE2, PE4, and PE6, since the organic disulfide compound (C) was not added as a polymerization raw material, the 1% thermogravimetric reduction temperature was lower and the thermal decomposition resistance (thermal stability) was lower than that of the DDS-added methacrylic copolymer (AC).

[0117] In Comparative Examples 1 to 9, a thermoplastic resin composition containing 1 to 99% by mass of the methacrylic copolymer (A) and 99 to 1% by mass of the thermoplastic resin (B) having good compatibility with the methacrylic copolymer (A) and not containing the organic disulfide compound (C) was obtained. All of the thermoplastic resin compositions obtained in these comparative examples had poor heat resistance and / or thermal decomposition resistance (thermal stability). In Comparative Examples 3, 4, and 6, further, foaming and / or generation of gel-like foreign substances due to thermal degradation of the resin were observed during the production of the thermoplastic resin composition and / or the molded article, and the resulting thermoplastic resin composition had poor transparency.

[0118] In Comparative Examples 10 to 14, a thermoplastic resin composition containing 1 to 99% by mass of the methacrylic copolymer (A) and 99 to 1% by mass of the thermoplastic resin (B) having poor compatibility with the methacrylic copolymer (A) and not containing the organic disulfide compound (C) was obtained. All of the thermoplastic resin compositions obtained in these comparative examples had poor heat resistance and thermal decomposition resistance (thermal stability). In the thermoplastic resin compositions obtained in these comparative examples, a decrease in rigidity was observed compared to the thermoplastic resin compositions obtained in Examples 10 to 14. In these comparative examples, it is presumed that during the production of the thermoplastic resin composition and / or the molded article, thermal degradation of the resin caused a decrease in the molecular weight of the resin and / or an increase in residual monomers, resulting in a decrease in rigidity.

[0119] The present invention is not limited to the above-described embodiments and examples, and design changes can be made as appropriate without departing from the spirit of the present invention.

Claims

1. 1 to 99% by mass of a methacrylic copolymer (A) composed of 40 to 99% by mass of methyl methacrylate units, 1 to 40% by mass of one or more isopropenyl aromatic compound units (UI), and 0 to 30% by mass of one or more other units (UO); 99 to 1% by mass of a thermoplastic resin (B) having a deflection temperature under load measured in accordance with JIS K 7191 A method other than the methacrylic copolymer (A) and being 60 to 150°C; A thermoplastic resin composition containing 1 to 1000 ppm of an organic disulfide compound (C).

2. The thermoplastic resin composition according to claim 1, wherein one or more isopropenyl aromatic compound units (UI) contain α-methylstyrene units.

3. The thermoplastic resin composition according to claim 1, wherein the methacrylic copolymer (A) contains, as other units (UO), aromatic vinyl compound units other than isopropenyl aromatic compound units.

4. The thermoplastic resin composition according to claim 1, wherein the methacrylic copolymer (A) contains, as other units (UO), one or more cyclic structure units (UR) selected from the group consisting of acid anhydride units, maleimide units, and lactone ring units.

5. The thermoplastic resin composition according to claim 1, wherein the glass transition temperature of the methacrylic copolymer (A) is 120 to 150°C.

6. The thermoplastic resin composition according to claim 1, wherein one or more organic disulfide compounds (C) contain di-tert-dodecyl disulfide (DDS).

7. The thermoplastic resin composition according to claim 1, wherein the total light transmittance measured in accordance with JIS K 7361-1 of a 3 mm-thick flat plate made of the thermoplastic resin composition is 80% or more.

8. A molded article containing the thermoplastic resin composition according to any one of claims 1 to 7.

9. A film containing the thermoplastic resin composition according to any one of claims 1 to 7.

10. A laminate containing a layer made of the thermoplastic resin composition according to any one of claims 1 to 7.

11. A step (S1) of producing an organic disulfide compound-added methacrylic copolymer (AC) containing a methacrylic copolymer (A) and an organic disulfide compound (C); A method for producing the thermoplastic resin composition according to any one of claims 1 to 7, comprising a step (S2) of melt-kneading 1 to 99% by mass of the organic disulfide compound-added methacrylic copolymer (AC) and 99 to 1% by mass of the thermoplastic resin (B).

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