Styrene resin composition and molded article

Abstract

To provide a styrene-based resin composition that generates an extremely small amount of a gelled substance and produces a molded article having excellent appearance.SOLUTION: The styrene-based resin composition includes a styrene-based resin and an ether compound. In the styrene-based resin composition, the styrene-based resin is produced by copolymerizing a monomer mixture including a styrene-based monomer and a (meth)acrylic acid-based monomer and the ether compound has a specific structure.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a styrene-based resin composition and a molded article.

Background Art

[0002] Styrene-(meth)acrylic acid copolymer resins are superior in heat resistance compared to general polystyrene and are mainly used as materials for food packaging materials for microwave heating. Specifically, after being formed into an extrusion foamed sheet or a biaxially stretched sheet, they are shaped into food containers and lids for use. Also, because they have an excellent balance of transparency and heat resistance, they are also suitable for light diffusing resin sheets containing a light diffusing agent, such as lighting covers and light diffusing plates for transmissive displays.

[0003] As drawbacks of styrene-(meth)acrylic acid copolymer resins, it has been pointed out that, due to the heat history during processing into a sheet or the like, the carboxyl groups in the polymer may undergo a condensation reaction between polymer molecules to form a gel-like substance, and that a gel-like substance may also be formed by a similar reaction even in the manufacturing process of the copolymer resin.

[0004] Patent Document 1 discloses a technique for suppressing the formation of a gel-like substance by adding a polyoxyethylene alkyl ether.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, even if the technique of Patent Document 1 is adopted, the formation of a gel-like substance cannot be completely suppressed, and it is desired to further suppress the formation of a gel-like substance.

[0007] The present invention has been made in view of such circumstances, and provides a styrene resin composition capable of effectively suppressing the formation of a gel-like substance.

Means for Solving the Problems

[0008] According to the present invention, there is provided a styrene resin composition containing a styrene resin and an ether compound, wherein the styrene resin is obtained by copolymerizing a monomer mixture containing a styrene monomer and a (meth)acrylic acid monomer, and the ether compound is represented by the general formula (1).

Effects of the Invention

[0009] As a result of intensive studies by the present inventors, it has been found that the formation of a gel-like substance can be effectively suppressed by adding the ether compound represented by the general formula (1), and the present invention has been completed.

Modes for Carrying Out the Invention

[0010] 1. Styrene Resin Composition The styrene resin composition of the present invention contains a styrene resin A and an ether compound B. Each component will be described in detail below.

[0011] <<Styrene Resin A>> The styrene resin A is obtained by copolymerizing a monomer mixture containing a styrene monomer and a (meth)acrylic acid monomer.

[0012] The styrenic monomer is a monocyclic or polycyclic aromatic vinyl monomer, for example, styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, 2,4-dimethylstyrene, 2,5-dimethylstyrene, 3,4-dimethylstyrene, 3,5-dimethylstyrene, p-ethylstyrene, m-ethylstyrene, o-ethylstyrene, p-tert-butylstyrene, 1-vinylnaphthalene, 2-vinylnaphthalene, 1,1-diphenylethylene, isopropenylbenzene (α-methylstyrene), isopropenyltoluene, isopropenylethylbenzene, isopropenylpropylbenzene, isopropenylbutylbenzene, isopropenylpentylbenzene, isopropenylhexylbenzene, isopropenyloctylbenzene, etc., either alone or as a mixture of two or more, preferably, styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, 2,4-dimethylstyrene, 2,5-dimethylstyrene, 3,4-dimethylstyrene, 3,5-dimethylstyrene, p-ethylstyrene, m-ethylstyrene, o-ethylstyrene, p-tert-butylstyrene, either alone or as a mixture of two or more, more preferably, styrene.

[0013] (Meth)acrylic acid monomers are one or both of acrylic acid monomers such as acrylic acid and methacrylic acid, preferably methacrylic acid.

[0014] The monomer mixture may contain only styrenic monomers and (meth)acrylic acid monomers, and may contain other monomers copolymerizable therewith as long as the effects of the present invention are not impaired. Examples of other monomers include vinyl cyanide monomers such as acrylonitrile and methacrylonitrile, acrylic monomers such as butyl acrylate, ethyl acrylate, methyl acrylate, methyl methacrylate, etc., α,β-ethylenically unsaturated carboxylic acids such as maleic anhydride and fumaric acid, and imide monomers such as phenylmaleimide and cyclohexylmaleimide.

[0015] The monomer mixture preferably contains styrene monomers and (meth)acrylic acid monomers as the main components. The total proportion of styrene monomers and (meth)acrylic acid monomers in the monomer mixture is preferably 50% by mass or more, for example, 50 to 100% by mass, specifically, for example, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100% by mass, and may be within the range between any two of the values exemplified herein.

[0016] With respect to 100% by mass of the styrene resin composition, the content of the structural unit derived from the (meth)acrylic acid monomer is preferably 0.1 to 30% by mass. The structural unit derived from the (meth)acrylic acid monomer is, for example, a (meth)acrylic acid monomer unit. If this value is too small, the heat resistance may be insufficient, and if this value is too large, the fluidity during melting may decrease and the moldability may deteriorate. Specifically, this proportion is, for example, 0.1, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 25, 30% by mass, and may be within the range between any two of the values exemplified herein.

[0017] The weight average molecular weight (Mw) of the styrene resin A is preferably 150,000 to 700,000, and preferably 150,000 to 400,000. Specifically, for example, it is 50,000, 100,000, 150,000, 200,000, 250,000, 300,000, 350,000, 400,000, 450,000, 500,000, 550,000, 600,000, 650,000, 700,000, and may be within the range between any two of the values exemplified herein. If Mw is too small, the strength of the molded product will be insufficient, and if Mw is too large, the moldability will decrease. The weight average molecular weight of the styrene resin A can be controlled by the reaction temperature, residence time, type and addition amount of the polymerization initiator, type and addition amount of the chain transfer agent, type and amount of the solvent used during polymerization, etc.

[0018] The weight average molecular weight (Mw) can be measured under the following conditions using gel permeation chromatography (GPC). GPC model: Shodex GPC-101 manufactured by Showa Denko K.K. Column: PLgel 10μm MIXED-B manufactured by Polymer Laboratories Mobile phase: Tetrahydrofuran Sample concentration: 0.2 mass% Temperature: Oven 40°C, Injection port 35°C, Detector 35°C Detector: Differential refractometer The molecular weight is calculated from the elution curve of monodisperse polystyrene for each elution time and is calculated as the molecular weight in terms of polystyrene conversion.

[0019] <<Ether compound B>> Ether compound B is represented by the general formula (1).

[0020] [Chemical formula]

[0021] Z1 to Z5 in the general formula (1) are the same or different and are a hydrogen atom or a hydrocarbon group which may have a hetero atom. It is preferable that three or four of Z1 to Z5 are hydrogen atoms and the rest are hydrocarbon groups which may have a hetero atom.

[0022] Examples of the hetero atom include oxygen, nitrogen, sulfur, fluorine, etc. The hydrocarbon group preferably has 1 to 30 carbon atoms, more preferably 2 to 20 carbon atoms. The number of carbon atoms is specifically, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, and may be within the range between any two of the numerical values exemplified here.

[0023] The hydrocarbon group is preferably an aliphatic hydrocarbon group which may have a substituent. Examples of the aliphatic hydrocarbon group include an alkyl group having 1 to 20 carbon atoms, an allyl group, a vinyl group, and the like. Specifically, the number of carbon atoms of the aliphatic hydrocarbon group is, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, and may be within the range between any two of the exemplified values. Examples of the substituent of the aliphatic hydrocarbon group include aromatic hydrocarbon groups such as a phenyl group. The aromatic hydrocarbon group may be substituted with a substituent such as a hydroxyl group. It is preferable that a substituent is bonded to the carbon at the 1-position of the aliphatic hydrocarbon group.

[0024] The hydrocarbon group may be an aromatic hydrocarbon group which may have a substituent. Examples of the aromatic hydrocarbon group include a phenyl group, a tolyl group, and the like. Examples of the substituent include aliphatic hydrocarbon groups such as alkyl and hydroxyl groups.

[0025] At least two of Z1 to Z5 may be crosslinked to form an alicyclic ring or an aromatic ring.

[0026] At least one of Z1 to Z5 is preferably an alkyl group having 1 to 20 carbon atoms which may have a substituent. This substituent is preferably a hydrocarbon group having 1 to 20 carbon atoms which may have a hetero atom, more preferably contains an aromatic ring, still more preferably a phenyl group bonded to the alkyl group, and still more preferably a 1-phenylethyl group.

[0027] In the general formula (1), n represents the number of carbon atoms of the alkylene oxide structure and is an integer of 1 to 10 (preferably 2 to 4). Specifically, n is, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, and may be within the range between any two of the exemplified values.

[0028] In the general formula (1), X represents the average addition number of alkylene oxide units and is an integer of 1 to 100 (preferably 5 to 50). Specifically, X is, for example, 1, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, and may also be within the range between any two of the numerical values exemplified herein.

[0029] Examples of the ether compound B include polyoxyethylene distyrenated phenyl ether, polyoxyethylene styrenated phenyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene nonyl phenyl ether, polyoxyethylene dodecyl phenyl ether, polyoxyethylene phenyl ether, polyoxyethylene β-naphthyl ether, polyoxyethylene bisphenol A ether, polyoxyethylene bisphenol F ether, and the like.

[0030] With respect to 100% by mass of the styrene resin composition, the content of the ether compound B is preferably 0.001 to 10% by mass. If this value is too small, the formation of the gel-like substance may not be sufficiently suppressed, and if this value is too large, the heat resistance may decrease. Specifically, the above content is, for example, 0.001, 0.01, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10% by mass, and may also be within the range between any two of the numerical values exemplified herein.

[0031] <<Other Additives>> In the styrene resin composition, various additives can be blended as needed within a range that does not impair the properties of the present invention. The type of additive is not particularly limited as long as it is generally used for plastics, and examples include antioxidants, flame retardants, lubricants, processing aids, antiblocking agents, antistatic agents, antifogging agents, light resistance improvers, softeners, plasticizers, inorganic reinforcing agents, crosslinking agents, pigments, dyes, and others or mixtures thereof. Further, the styrene resin composition may contain only ether compound B as the ether compound, or may contain an ether compound other than ether compound B (e.g., polyoxyethylene alkyl ether).

[0032] 2. Method for producing styrene resin composition The styrene resin composition of the present invention can be produced by adding ether compound B to styrene resin A. Examples of the polymerization method of the styrene resin include known styrene polymerization methods such as bulk polymerization method, solution polymerization method, suspension polymerization method, and emulsion polymerization method. From the viewpoints of quality and productivity, the bulk polymerization method and the solution polymerization method are preferred, and continuous polymerization is preferred. As the solvent, for example, alkylbenzenes such as benzene, toluene, ethylbenzene, and xylene, ketones such as acetone and methyl ethyl ketone, and aliphatic hydrocarbons such as hexane and cyclohexane can be used.

[0033] When polymerizing the styrene-(meth)acrylic acid copolymer resin, polymerization aids such as a polymerization initiator, a chain transfer agent, a crosslinking agent, and other polymerization aids can be used as needed. As the polymerization initiator, a radical polymerization initiator is preferred, and known and commonly used examples include peroxyketals such as 1,1-di(t-butylperoxy)cyclohexane, 2,2-di(t-butylperoxy)butane, 2,2-di(4,4-di-t-butylperoxycyclohexyl)propane, 1,1-di(t-amylperoxy)cyclohexane, hydroperoxides such as cumene hydroperoxide, t-butyl hydroperoxide, alkyl peroxides such as t-butyl peroxyacetate, t-amyl peroxyisooctanoate, dialkyl peroxides such as t-butyl cumyl peroxide, di-t-butyl peroxide, dicumyl peroxide, di-t-hexyl peroxide, peroxy esters such as t-butyl peroxyacetate, t-butyl peroxybenzoate, t-butyl peroxyisopropyl monocarbonate, peroxy carbonates such as t-butyl peroxyisopropyl carbonate, polyether tetrakis(t-butyl peroxycarbonate), N,N'-azobis(cyclohexane-1-carbonitrile), N,N'-azobis(2-methylbutyronitrile), N,N'-azobis(2,4-dimethylvaleronitrile), N,N'-azobis[2-(hydroxymethyl)propionitrile], etc. One or more of these can be used in combination. Examples of the chain transfer agent include aliphatic mercaptan, aromatic mercaptan, pentaphenylethane, α-methylstyrene dimer, and terpinolene.

[0034] In the case of continuous polymerization, the styrene resin composition can be produced by a method comprising a polymerization step, a devolatilization step, and a granulation step.

[0035] First, in the polymerization step, a known fully mixed tank type stirring tank, a tower type reactor, etc. are used, and the polymerization reaction is controlled by adjusting the polymerization temperature, etc. so as to achieve the target molecular weight, molecular weight distribution, and reaction conversion rate.

[0036] The polymerization solution containing the polymer that has exited the polymerization process is transferred to the devolatilization process, where unreacted monomers and the polymerization solvent are removed. The devolatilization process is composed of a vacuum devolatilization tank with a heater, a devolatilization extruder with a vent, etc. The polymer in the molten state that has exited the devolatilization process is transferred to the pelletizing process. In the pelletizing process, the molten resin is extruded in a strand shape from a porous die and processed into a pellet shape by a cold cut method, an air hot cut method, or a water hot cut method.

[0037] The ether compound B is preferably added before the devolatilization process or during the devolatilization process. Specifically, the ether compound B is preferably added by any of the following methods (1) to (4). (1) Add to the monomer mixture of the raw materials. (2) Add during the polymerization process. (3) Add to the polymerization solution after the completion of the polymerization process. (4) When the devolatilization process is composed of two stages and the resin temperature in the first stage is less than 200 °C, add between the first stage and the second stage.

[0038] 3. Uses of the styrene resin composition The styrene resin composition of the present invention can be formed into a molded product by a molding method according to the purpose, such as injection molding, extrusion molding, compression molding, blow molding, etc., and its shape is not limited. For example, if it is a plate-shaped molded product, it can be processed into a light guide plate, etc.

Examples

[0039] Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples.

[0040] 1. Measurement method (1) Measurement of the methacrylic acid unit content Weigh 0.5 g of the styrene resin composition, dissolve it in a mixed solution of toluene / ethanol = 8 / 2 (volume ratio), perform neutralization titration with a 0.1 mol / L ethanol solution of potassium hydroxide, detect the end point, and calculate the content of the methacrylic acid unit based on mass from the usage amount of the potassium hydroxide ethanol solution.

[0041] (2) Measurement of the content of ether compounds Weigh 5 g of the styrene resin composition and dissolve it in THF. After dissolution, reprecipitate the polymer component with methanol and a small amount of hydrochloric acid, and remove the precipitate by filtration. Concentrate the filtrate and finally obtain a concentrated solution of 10 ml of methanol solution. Quantify the ether compound by high performance liquid chromatography (HPLC). For quantification, a calibration curve was created by preparing three points of methanol solutions with known ether compound concentrations. HPLC model: Alliance System 2695 Separation Module manufactured by Waters Corporation, Japan Detector: Differential refractometer (RI) Column: TSKgel ODS-120T 4.6 mm (ID) × 15 cm (L) manufactured by Tosoh Corporation Mobile phase: Methanol / water = 80 / 20 (volume ratio) with 0.2 mass% phosphoric acid added Flow rate: 1.0 ml / min Column oven temperature: 40 °C Detector temperature: 30 °C

[0042] (3) Measurement of Vicat softening temperature Determined according to JIS K-7206 at a heating rate of 50 °C / hr and a test load of 50 N.

[0043] (4) Measurement of MEK insoluble matter <Before heating> Weigh 1 g of the styrene resin composition, add 35 ml of methyl ethyl ketone and dissolve it. Centrifuge the solution in a centrifuge (H-2000B manufactured by Kokusan Co., Ltd. (rotor: H)) at 10,000 rpm for 30 minutes to sediment the insoluble matter. Remove the supernatant by decantation to obtain the insoluble matter. Pre-dry it in a safety oven at 90 °C for 2 hours, further dry it under reduced pressure in a vacuum dryer at 120 °C for 1 hour, cool it in a desiccator for 20 minutes, and then measure the mass G of the dried insoluble matter to calculate the mass% of the insoluble matter.

[0044] <After heating> Weighed 1 g of the styrene resin composition and carried out heat treatment in an oven at 230 °C for 3 hours under vacuum. Then, the insoluble matter was measured in the same manner as before the heating, and the mass percentage of the insoluble matter was calculated. The gel-like substance is considered to be formed by the condensation reaction of carboxyl groups in the styrene resin between polymer molecules and is a component insoluble in methyl ethyl ketone.

[0045] (5) Measurement of Haze Pellets of the styrene resin composition were injection-molded using an injection molding machine (IS130FII-3A) manufactured by Toshiba Machine Co., Ltd. at a cylinder temperature of 250 °C and a mold temperature of 50 °C. Using the obtained test pieces (thickness 2 mm, dimensions 40 mm × 40 mm), Haze (unit: %) was measured in accordance with JIS K-7105 using a haze meter (NDH5000 manufactured by Nippon Denshoku Industries Co., Ltd.).

[0046] 2. Examples and Comparative Examples Examples and comparative examples were carried out by the methods shown below.

[0047] <Example 1> A polymerization step was configured by connecting in series a first reactor, which is a completely mixed stirred tank with an internal volume of 39 liters, and a second reactor, which is a completely mixed stirred tank with an internal volume of 39 liters. A raw material solution consisting of a mixed solution of 71% by mass of styrene, 12% by mass of methacrylic acid, and 17% by mass of ethylbenzene was prepared.

[0048] This raw material solution was continuously supplied to the first reactor at a rate of 12.6 kg per hour, and each reactor was circulated in a full liquid state. At the inlet of the first reactor, 1,1-bis(t-butylperoxy)cyclohexane (Perhexa C manufactured by NOF Corporation) was mixed at 250 ppm on a mass basis with respect to the total amount of styrene and methacrylic acid in the raw material solution. Also, the ether compound [B-1] was continuously added at the inlet of the first reactor. The reaction temperature of each reactor was adjusted to 130 °C in the first reactor and 140 °C in the second reactor.

[0049] Subsequently, the solution containing the copolymer resin continuously taken out from the second reactor was introduced into a vacuum devolatilization tank with a preheater installed in two stages in series. After separating unreacted monomers and ethylbenzene, it was extruded into strands, cooled, and then cut into pellets to obtain a styrene-based resin composition. For the first-stage vacuum devolatilization tank with a preheater, the temperature of the preheater was set at 175°C, the pressure of the vacuum devolatilization tank was set at 500 mmHg, and the jacket temperature of the vacuum devolatilization tank was set at 185°C. For the second-stage vacuum devolatilization tank with a preheater, the temperature of the preheater was set at 240°C, the pressure of the vacuum devolatilization tank was set at 8 mmHg, and the jacket temperature of the vacuum devolatilization tank was set at 240°C. The resin temperature in the first-stage vacuum devolatilization tank was 168°C, and the resin temperature in the second-stage vacuum devolatilization tank was 231°C.

[0050] For the obtained styrene-based resin composition, various physical properties were measured. The results are shown in Table 1.

[0051]

Table 1

[0052] The details of the components in Table 1 are as follows. Ether compound B B-1: Polyoxyethylene distyrenated phenyl ether (manufactured by Kao Corporation, Emulgen A-90, average added number of ethylene oxide units 18) B-2: Polyoxyethylene distyrenated phenyl ether (manufactured by Kao Corporation, Emulgen A-60, average added number of ethylene oxide units 12) B-3: Polyoxyethylene distyrenated phenyl ether (manufactured by Kao Corporation, Emulgen A-500, average added number of ethylene oxide units 50) B-4: Polyoxyethylene styrenated phenyl ether (manufactured by Aoki Yushi Kogyo Co., Ltd., KTSP-16, average added number of ethylene oxide units 16) B-5: Polyoxyethylene nonylphenyl ether (manufactured by Aoki Yushi Kogyo Co., Ltd., Braunon N-513, average added number of ethylene oxide units 13) Polyoxyethylene alkyl ether (polyoxyethylene lauryl ether) (manufactured by Kao Corporation, Emulgen 109P, average number of added ethylene oxide units 9)

[0053] <Examples 2 to 9> A styrene resin composition was produced in the same manner as in Example 1 except that the type and / or amount of the ether compound B was changed as shown in Table 1, and various physical properties were measured.

[0054] <Example 10> A styrene resin composition was produced in the same manner as in Example 1 except that the raw material solution was changed to a mixed solution of 77.1% by mass of styrene, 5.9% by mass of methacrylic acid, and 17% by mass of ethylbenzene, and various physical properties were measured.

[0055] <Example 11> A styrene resin composition was produced in the same manner as in Example 3 except that the raw material solution was changed to a mixed solution of 63.5% by mass of styrene, 19.5% by mass of methacrylic acid, and 17% by mass of ethylbenzene, and various physical properties were measured.

[0056] <Comparative Examples 1 to 3> A styrene resin composition was produced in the same manner as in Examples 1, 10, and 11 except that no ether compound was added, and various physical properties were measured.

[0057] <Comparative Examples 4 to 6> A styrene resin composition was produced in the same manner as in Examples 1, 4, and 10 except that polyoxyethylene alkyl ether was added instead of the ether compound B, and various physical properties were measured.

[0058] 3. Discussion In all the examples, the increase in MEK-insoluble content due to heating was very small. Since the MEK-insoluble content is mainly a gel-like substance, it was demonstrated that the formation of the gel-like substance was suppressed. Further, when comparing Examples 1, 4, and 10 with Comparative Examples 4 to 6, when a polyoxyethylene alkyl ether was added instead of the ether compound B, the Vicat softening temperature decreased significantly.

Industrial Applicability

[0059] By using the styrene resin composition of the present invention, a resin composition and a molded article with extremely few gels can be produced, and a molded article with excellent appearance can be obtained. In addition, the generation of gels in the manufacturing process can be suppressed more than before, and the production efficiency can be increased.

Claims

1. A styrenic resin composition for molding, comprising a styrenic resin and an ether compound, wherein the molding is injection molding, extrusion molding, compression molding, or blow molding, the styrenic resin is obtained by copolymerizing a monomer mixture containing a styrenic monomer and methacrylic acid, the total proportion of the styrenic monomer and methacrylic acid in the monomer mixture is 50% by mass or more, the content of the structural unit derived from methacrylic acid is 3 to 30% by mass based on 100% by mass of the styrenic resin composition, the ether compound is represented by the general formula (1) (however, excluding those in which the styrenic resin is in particulate form and dispersed in water, and those in which the styrenic resin composition contains a layered compound). 【Chemical 1】 (In the formula, Z1 to Z5 are the same or different and are each a hydrogen atom or a hydrocarbon group which may have a hetero atom. At least two of Z1 to Z5 may be crosslinked to form an alicyclic or aromatic ring. n represents the number of carbon atoms of the alkylene oxide structure and is an integer of 1 to 10. X represents the average addition number of alkylene oxide units and is an integer of 1 to 100.)

2. The styrenic resin composition according to claim 1, wherein the content of the ether compound is 0.001 to 10% by mass based on 100% by mass of the styrenic resin composition.

3. The styrenic resin composition according to claim 1 or claim 2, wherein at least one of Z1 to Z5 is an alkyl group having 1 to 20 carbon atoms which may have a substituent.

4. The styrenic resin composition according to claim 3, wherein the substituent is a hydrocarbon group having 1 to 20 carbon atoms which may have a hetero atom.

5. The styrenic resin composition according to claim 4, wherein the substituent contains an aromatic ring.

6. The styrenic resin composition according to claim 5, wherein the aromatic ring of the substituent is a phenyl group bonded to the alkyl group.

7. The styrenic resin composition according to claim 6, wherein the substituent is a 1-phenylethyl group.

8. The styrenic resin composition according to any one of claims 1 to 7, A styrene resin composition in which the number of carbon atoms n of the alkylene oxide structure is 2 to 4.

9. A styrene resin composition according to any one of Claims 1 to 8, A styrene resin composition in which the average number of added moles of the alkylene oxide unit is 5 to 50.

10. A molded article comprising the styrene resin composition according to any one of Claims 1 to 9.

11. A method for producing a styrene resin composition for molding, comprising a styrene resin and an ether compound, wherein the molding is injection molding, extrusion molding, compression molding, or blow molding, the method comprises a polymerization step and a subsequent devolatilization step, in the polymerization step, a monomer mixture containing a styrene monomer and methacrylic acid is copolymerized, in the devolatilization step, unreacted monomers in the monomer mixture are removed, the ether compound is added before or during the devolatilization step, the total proportion of the styrene monomer and methacrylic acid in the monomer mixture is 50% by mass or more, the content of the structural unit derived from methacrylic acid is 0.1 to 30 mass with respect to 100 mass% of the styrene resin composition, the ether compound is represented by the general formula (1) (however, excluding those in which the styrene resin contained in the styrene resin composition is in the form of fine particles and dispersed in water). 【Chemical 1】 (In the formula, Z1 to Z5 are the same or different and are each a hydrogen atom or a hydrocarbon group which may have a hetero atom. At least two of Z1 to Z5 may be crosslinked to form an alicyclic ring or an aromatic ring. n represents the number of carbon atoms of the alkylene oxide structure and is an integer of 1 to 10. X represents the average number of added moles of the alkylene oxide unit and is an integer of 1 to 100.)

12. A method for producing a styrene resin composition for molding, comprising a styrene resin and an ether compound, wherein the molding is injection molding, extrusion molding, compression molding, or blow molding, the method comprises a polymerization step and a subsequent devolatilization step, in the polymerization step, a monomer mixture containing a styrene monomer and methacrylic acid is copolymerized, the copolymerization is solution polymerization or bulk polymerization, in the devolatilization step, unreacted monomers are removed, the ether compound is added before or during the devolatilization step, the total proportion of the styrene monomer and methacrylic acid in the monomer mixture is 50% by mass or more, With respect to 100% by mass of the styrene resin composition, the content of the structural unit derived from methacrylic acid is 0.1 to 30% by mass, The ether compound is a method for producing a styrene resin composition represented by the general formula (1). 【Chemical 1】 (Z1 to Z5 in the formula are the same or different and are each a hydrogen atom or a hydrocarbon group which may have a hetero atom. At least two of Z1 to Z5 may be crosslinked to form an alicyclic ring or an aromatic ring. n represents the number of carbon atoms in the alkylene oxide structure and is an integer of 1 to 10. X represents the average addition number of alkylene oxide units and is an integer of 1 to 100.)

13. The method according to claim 12, The copolymerization is solution polymerization in which the copolymerization is carried out in the presence of a polymerization solvent, In the devolatilization step, the unreacted monomer and the polymerization solvent are removed.

14. A method for producing a styrene resin composition for molding containing a styrene resin and an ether compound, The molding is injection molding, extrusion molding, compression molding, or blow molding, The method includes a polymerization step, In the polymerization step, a monomer mixture containing a styrene monomer and methacrylic acid is copolymerized, The copolymerization is solution polymerization or bulk polymerization, The ether compound is added before or during the copolymerization, The total ratio of the styrene monomer and methacrylic acid in the monomer mixture is 50% by mass or more, With respect to 100% by mass of the styrene resin composition, the content of the structural unit derived from methacrylic acid is 0.1 to 30% by mass, The ether compound is a method for producing a styrene resin composition represented by the general formula (1). 【Chemical 1】 (Z1 to Z5 in the formula are the same or different and are each a hydrogen atom or a hydrocarbon group which may have a hetero atom. At least two of Z1 to Z5 may be crosslinked to form an alicyclic ring or an aromatic ring. n represents the number of carbon atoms in the alkylene oxide structure and is an integer of 1 to 10. X represents the average addition number of alkylene oxide units and is an integer of 1 to 100.)

15. The method according to claim 14, The method includes a devolatilization step after the polymerization step, In the devolatilization step, the unreacted monomer is removed.

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