Styrenic resin composition, extruded sheet, container, and injection molded article

Abstract

To provide a styrenic resin composition, an extrusion sheet and a container, which are used in a molding excellent in heat resistance, mechanical strength and low temperature strength.SOLUTION: A styrenic resin composition contains 35 mass% or more and less than 100 mass% of a styrene-unsaturated carboxylic resin (A) having a styrenic monomer unit (1) and an unsaturated carboxylic acid-based monomer unit (a1), and more than 0 mass% and 65 mass% or less of a (meth)acrylic resin (B) having a (meth)acrylate monomer unit (b1), wherein (b1) is composed of a (meth)acrylate monomer unit (b1-0) having an ester substituent group with 1 carbon atom, a (meth)acrylate monomer unit (b1-1) having an ester substituent group with 2 to 10 carbon atoms and a (meth)acrylate monomer unit (b1-2) having an ester substituent group with more than 10 carbon atoms, and in (b1) contained in the resin (B), a content of (b1-1) is more than 35 mass%.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present disclosure relates to a styrene-based resin composition, an extruded sheet formed using the styrene-based resin composition, and a container and an injection-molded article formed by secondary molding of the extruded sheet. [Background technology]

[0002] Styrene-unsaturated carboxylic acid resins, such as styrene-methacrylic acid copolymer resins, are excellent in heat resistance, transparency, rigidity, and appearance, and are inexpensive, and therefore are widely used in packaging materials for food containers such as lunch boxes and prepared foods, foam boards for insulating houses, and diffusion plates for LCD televisions containing a diffusion agent. In particular, with the recent widespread use of high-power microwave ovens for commercial use in convenience stores and the like, styrene-unsaturated carboxylic acid resins are being used as materials for containers that can withstand the temperatures used during cooking in high-power microwave ovens, and for lids that seal or cover these containers. However, the problem is that they have lower strength than general-purpose styrene resins.

[0003] For example, Patent Document 1 describes a technology for improving toughness while maintaining practical heat resistance by using a mixture of a styrene-methacrylic acid copolymer, impact-resistant polystyrene, and a methyl methacrylate-butadiene-styrene copolymer (hereinafter also referred to as MBS resin). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2018-44086 A Summary of the Invention [Problem to be solved by the invention]

[0005] The technology of Patent Document 1 mentioned above did not improve mechanical strength sufficiently. It was confirmed that the impact strength was particularly low at low temperatures (-10°C to 30°C). In particular, in response to the recent rise in environmental issues such as the SDGs, resin materials are required to have mechanical strength at low temperatures in order to realize containers that can be transported and displayed frozen in order to reduce food waste. This demand for improved low-temperature strength is also required for heat-resistant containers that can withstand the temperatures used during cooking in the above-mentioned high-power microwave ovens.

[0006] An object of the present invention is to provide a styrene-based resin composition for use in moldings having excellent heat resistance, mechanical strength and low-temperature strength. Another problem to be solved by the present invention is to provide a molded article, an extruded sheet, and a container obtained by secondary molding of the foamed extruded sheet, which are excellent in heat resistance, mechanical strength, and low-temperature strength. [Means for solving the problem]

[0007] The present inventors have conducted intensive research in view of the above problems, and as a result, have succeeded in realizing a styrene-based resin composition that exhibits excellent heat resistance, mechanical strength, and low-temperature strength when molded by containing a predetermined amount of a styrene-unsaturated carboxylic acid-based resin (A) and a (meth)acrylic-based resin (B), an extruded sheet using the composition, and a container obtained by secondary molding of the extruded sheet, thereby completing the present invention. That is, the present disclosure is as follows.

[0008] [1] 35% by mass or more and less than 100% by mass of a styrene-unsaturated carboxylic acid resin (A) having a styrene-based monomer unit (1) and an unsaturated carboxylic acid-based monomer unit (a1); and (meth)acrylic resin (B) having (meth)acrylic acid ester monomer units (b1) in an amount of more than 0 mass % and not more than 65 mass %, wherein the (meth)acrylic acid ester monomer units (b1) are composed of one or more types selected from the group consisting of (meth)acrylic acid ester monomer units (b1-0) having an ester substituent with 1 carbon atom, (meth)acrylic acid ester monomer units (b1-1) having an ester substituent with 2 to 10 carbon atoms, and (meth)acrylic acid ester monomer units (b1-2) having an ester substituent with more than 10 carbon atoms, A styrene-based resin composition, in which the (meth)acrylic acid ester monomer units (b1) contained in the (meth)acrylic resin (B) have a content of the (meth)acrylic acid ester monomer units (b1-1) of more than 35 mass%.

[0009] [2] The styrene-based resin composition according to [1], wherein the content of the (meth)acrylic acid ester monomer unit (b1-1) is more than 45 mass% based on the total amount of the (meth)acrylic resin (B).

[0010] [3] The styrene-based resin composition according to [1] or [2], wherein the (meth)acrylic resin (B) is a block copolymer and contains one or more selected from the group consisting of a methacrylic polymer block (B1) having a methyl methacrylate monomer content of 90 mass% or more and an acrylic polymer block (B2) having an acrylic ester monomer unit content of 90 mass% or more.

[0011] [4] The styrene-based resin composition according to any one of [1] to [3], wherein the (meth)acrylic resin (B) is any one of a methyl methacrylate-butyl acrylate copolymer, a methyl methacrylate-acrylic (2-ethylhexyl) copolymer, and a methyl methacrylate-acrylic (butyl)-acrylic (2-ethylhexyl) copolymer.

[0012] [5] The styrene-based resin composition according to any one of [1] to [4], further comprising 0.001 to 1.0 part by mass of a monohydric alcohol (C) having 10 or more carbon atoms relative to the total amount (100 parts by mass) of the styrene-based resin composition.

[0013] [6] The styrene-based resin composition according to any one of [1] to [5], wherein a high molecular weight component having a molecular weight of 1,000,000 or more in the entire styrene-based resin composition is 5.0 mass% or less based on the total amount of the styrene-based resin composition.

[0014] [7] The styrene-based resin composition according to any one of [1] to [6], wherein the unsaturated carboxylic acid-based monomer unit (a1) is at least one selected from the group consisting of the (meth)acrylic acid monomer unit (a1-1) and the (meth)acrylic acid ester monomer unit (a1-2).

[0015] [8] The unsaturated carboxylic acid monomer unit (a1) contains two essential components, namely, a (meth)acrylic acid monomer unit (a1-1) and a (meth)acrylic acid ester monomer unit (a1-2), The styrene-based resin composition according to any one of [1] to [7], comprising 2 to 30 mass% of the (meth)acrylic acid monomer unit (a1-1) and 0.01 to 20 mass% of the (meth)acrylic acid ester monomer unit (a1-2) relative to the total amount of the styrene-based resin-unsaturated carboxylic acid-based resin (A).

[0016] [9] The styrene-based resin composition according to any one of [1] to [8], further comprising one or more selected from the group consisting of core-shell type rubber-like polymer particles (D) containing (meth)acrylic acid ester monomer units (d1) and conjugated diene monomer units (d2), impact resistant styrene-based resins (E) containing styrene-based monomer units (e1) and conjugated diene monomer units (e2), styrene-based elastomers (F), (meth)acrylonitrile-diene-styrene-based resins (G) containing styrene-based monomer units (g1), conjugated diene monomer units (g2), and (meth)acrylonitrile-based monomer units (g3), and acrylic resins (H).

[0017]

[10] The styrene-based resin composition according to [9], comprising the styrene-unsaturated carboxylic acid-based resin (A), the (meth)acrylic resin (B), the (meth)acrylonitrile-diene-styrene-based resin (G) and the acrylic resin (H).

[0018]

[11] An extruded sheet for non-foaming or foaming, comprising the styrene-based resin composition according to any one of the items [1] to

[10] .

[0019]

[12] A container obtained by molding the styrene-based resin composition according to any one of the items [1] to

[10] .

[0020]

[13] A structure obtained by injection molding the styrene-based resin according to any one of the items [1] to

[10] . Effect of the Invention

[0021] According to the present disclosure, there is provided a styrene-based resin composition for use in molded articles having excellent heat resistance, mechanical strength, and low-temperature strength. According to the present disclosure, it is possible to provide an extruded sheet and a microwaveable container having excellent heat resistance, mechanical strength, and low-temperature strength. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Hereinafter, an embodiment of the present invention (hereinafter, referred to as "the present embodiment") will be described in detail. Note that the present invention is not limited to the following embodiment, and can be modified in various ways within the scope of the gist of the present invention. [Styrene-based resin composition] The styrene-based resin composition (hereinafter, also simply referred to as a resin composition) in this embodiment contains a styrene-unsaturated carboxylic acid-based resin (A) and a (meth)acrylic resin (B). The styrene-unsaturated carboxylic acid-based resin (A) has a styrene-based monomer unit (1) and an unsaturated carboxylic acid-based monomer unit (a1). The (meth)acrylic resin (B) has a (meth)acrylic acid ester monomer unit (b1). The (meth)acrylic acid ester monomer unit (b1) includes a (meth)acrylic acid ester monomer unit (b1-0) in which the ester substituent has 1 carbon atom, a (meth)acrylic acid ester monomer unit (b1-1) in which the ester substituent has 2 to 10 carbon atoms, and a (meth)acrylic acid ester monomer unit (b1-2) in which the ester substituent has more than 10 carbon atoms. Among the (meth)acrylic acid ester monomer units (b1) contained in the (meth)acrylic resin (B), the content of (meth)acrylic acid ester monomer units (b1-1) having an ester substituent with 2 to 10 carbon atoms exceeds 35 mass%. The content of the styrene-unsaturated carboxylic acid resin (A) is 35 mass% or more and less than 100 mass%, and the content of the (meth)acrylic resin (B) is more than 0 mass% and 65 mass% or less, relative to the total amount (100 mass%) of the styrene resin composition. This makes it possible to provide a styrene-based resin composition which can be used to produce molded articles having excellent heat resistance, mechanical strength and low-temperature strength.

[0023] In addition, the styrene-based resin composition in this embodiment may contain, as necessary, one or more selected from the group consisting of a monohydric alcohol having 10 or more carbon atoms (C), a core-shell type rubbery polymer particle (D), an impact resistant styrene-based resin (E), a styrene-based elastomer (F), a (meth)acrylonitrile-diene-styrene-based resin (G), and an acrylic resin (H). This further makes it possible to provide a styrene-based resin composition having superior heat resistance, mechanical strength and low-temperature strength. Hereinafter, each of the constituent components of the styrene-based resin composition of the present disclosure will be described.

[0024] "Styrene-unsaturated carboxylic acid resin (A)" The styrene-unsaturated carboxylic acid resin (A) in this embodiment is a copolymer resin (hereinafter also simply referred to as resin (A)) consisting essentially of styrene monomer units (1) and unsaturated carboxylic acid monomer units (a1), and contributes to improving the heat resistance of the entire styrene resin composition. In addition, the styrene-unsaturated carboxylic acid resin (A) may further contain other monomer units (a2) other than the essential components of the styrene monomer units (1) and unsaturated carboxylic acid monomer units (a1), if necessary. In the styrene-based resin composition of this embodiment, the content of the styrene-unsaturated carboxylic acid resin (A) is 35% by mass or more and less than 100% by mass with respect to the total amount (100% by mass) of the styrene-based resin composition. The lower limit of the content of the styrene-unsaturated carboxylic acid resin (A) is preferably 37% by mass or more, 39% by mass or more, 41% by mass or more, 43% by mass or more, 45% by mass or more, 47% by mass or more, 49% by mass or more, 51% by mass or more, 53% by mass or more, 55% by mass or more, and 60% by mass or more in that order. The upper limit of the content of the styrene-unsaturated carboxylic acid resin (A) is preferably 98% by mass or less, 97% by mass or less, 95% by mass or less, 93% by mass or less, 91% by mass or less, 89% by mass or less, 87% by mass or less, 85% by mass or less, 83% by mass or less, 81% by mass or less, 79% by mass or less, 77% by mass or less, and 75% by mass or less in that order. The content range of the styrene-unsaturated carboxylic acid resin (A) may be any combination of the above lower and upper limits.

[0025] In particular, by making the content of the styrene-unsaturated carboxylic acid resin (A) 45% by mass or more based on the total amount (100% by mass) of the styrene-based resin composition, the effect of imparting heat resistance can be sufficiently obtained. On the other hand, by making the content of the styrene-unsaturated carboxylic acid resin (A) 81% by mass or less based on the total amount (100% by mass) of the styrene-based resin composition, the effect of improving low-temperature strength by adding the (meth)acrylic resin (B) described later can be sufficiently obtained. The styrene-unsaturated carboxylic acid resin (A) of the present embodiment is preferably a random copolymer.

[0026] <Styrene-based monomers (1)> In the styrene-unsaturated carboxylic acid resin (A) of this embodiment, the content of the styrene-based monomer unit (1) is 50 to 99 mass%, preferably 70 to 97 mass%, more preferably 80 to 96 mass%, and even more preferably 82 to 95 mass%, based on the total amount of the styrene-unsaturated carboxylic acid resin (A). If the content of the styrene-based monomer unit (1) is less than 50 mass%, the flowability is reduced, and if it is more than 99 mass%, it becomes difficult to contain a desired amount of the unsaturated carboxylic acid monomer unit (a1) described below, and the effect of improving heat resistance by the unsaturated carboxylic acid monomer unit (a1) (especially, the (meth)acrylic acid monomer unit (a1-1)) is not sufficiently obtained.

[0027] In the styrene-based resin composition of the present embodiment, the styrene-based monomer unit (1) is preferably contained in an amount of 30 to 85 mass%, more preferably 40 to 82 mass%, more preferably 45 to 79 mass%, and even more preferably 49 to 77 mass%, based on the total amount of the styrene-based resin composition. When the content of the styrene-based monomer (1) in the entire composition is within the above range, a resin composition having flowability that is easy to mold can be obtained.

[0028] In this embodiment, the styrene-based monomer (1) is not particularly limited, but examples thereof include styrene, α-methylstyrene, β-methylstyrene, paramethylstyrene, orthomethylstyrene, metamethylstyrene, chlorostyrene, bromostyrene, etc. From an industrial viewpoint, styrene and α-methylstyrene are particularly preferred, and styrene is more preferred. As the styrene-based monomer (1), these may be used alone or in combination of two or more.

[0029] In this specification, the term "styrene monomer unit (1)" refers to a repeating unit constituting a polymer obtained by polymerizing a styrene monomer (1), and is a repeating unit (or structural unit) in which the carbon-carbon double bond in the styrene monomer (1) becomes a single bond (-CC-) through a polymerization reaction or crosslinking reaction of the styrene monomer (1). Other monomer units in this specification have the same meaning.

[0030] <Unsaturated carboxylic acid monomer (a1)> In the styrene-unsaturated carboxylic acid resin (A) of this embodiment, the unsaturated carboxylic acid monomer unit (a1) plays a role in improving heat resistance and compatibility with the (meth)acrylic resin (B) described below. The content of the unsaturated carboxylic acid monomer unit (a1) is 2 to 40 mass% relative to the total amount of the styrene-unsaturated carboxylic acid resin (A), preferably 3 to 35 mass%, more preferably 5 to 30 mass%, even more preferably 8 to 25 mass%, and even more preferably 10.5 to 20 mass%. By making the content of the unsaturated carboxylic acid monomer unit (a1) 2 mass% or more, an effect of improving the heat resistance of the styrene-unsaturated carboxylic acid resin (A) and the resin composition can be obtained, and by making it 40 mass% or less, a styrene resin composition excellent in processability and dimensional stability can be obtained. In particular, by setting the content of the unsaturated carboxylic acid monomer unit (a1) in the range of 10.5 to 20 mass% relative to the total amount of the styrene-unsaturated carboxylic acid resin (A), good compatibility with the (meth)acrylic resin (B) can be obtained, and a composition excellent in mechanical strength can be obtained.

[0031] The unsaturated carboxylic acid monomer unit (a1) in this embodiment includes an unsaturated carboxylic acid and its ester, and specifically includes a (meth)acrylic acid monomer unit (a1-1) and a (meth)acrylic acid ester monomer unit (a1-2).

[0032] -(Meth)acrylic acid monomer unit (a1-1)- In this embodiment, the (meth)acrylic acid monomer unit (a1-1) plays a role of improving heat resistance. The (meth)acrylic acid monomer (a1-1) may be acrylic acid or methacrylic acid. From an industrial viewpoint, the (meth)acrylic acid monomer unit (a1-1) may be used alone or in combination of two or more. As the (meth)acrylic acid monomer unit (a1-1), methacrylic acid, which has a large effect of improving heat resistance, is particularly preferred.

[0033] In this embodiment, the content of the (meth)acrylic acid monomer unit (a1-1) is preferably in the range of 2 to 40 mass%, more preferably 3 to 20 mass%, even more preferably 4 to 17 mass%, and even more preferably 8 to 14 mass% relative to the total amount of the styrene-unsaturated carboxylic acid resin (A). By making the content of the (meth)acrylic acid monomer unit (a1-1) 2 mass% or more, it is possible to obtain an effect of improving heat resistance, and by making the content 40 mass% or less, it is possible to suppress an excessive increase in viscosity. In particular, by making the content in the range of 8 to 13 mass%, it is possible to obtain a styrene-unsaturated carboxylic acid resin (A) that achieves both a high effect of improving heat resistance and suppression of gel generation to a level applicable to transparent sheet applications.

[0034] -(Meth)acrylic acid ester monomer (a1-2)- In this embodiment, the (meth)acrylic acid ester monomer (a1-2) plays a role in improving the strength and the compatibility with the (meth)acrylic resin described below. As the (meth)acrylic acid ester monomer (a1-2), a monomer represented by the following general formula (1) [ka]

[0035] (In the above general formula (1), R 1 represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, R 2 represents an ester substituent, specifically, represents an alkyl group having 1 to 12 carbon atoms.

[0036] In this embodiment, the ester substituent of the (meth)acrylic acid ester monomer unit (a1-2) (R 2 The number of carbon atoms in is preferably 10 or less, more preferably 8 or less, even more preferably 4 or less, and still more preferably 2 or less. If the number exceeds 10, the effect of lowering heat resistance is significant, which is not preferred.

[0037] Examples of the (meth)acrylic acid ester monomer (a1-2) in this embodiment include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, cyclohexyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and decyl (meth)acrylate. These can be used alone or in combination. As the (meth)acrylic acid ester monomer (a1-2), methyl (meth)acrylate or butyl (meth)acrylate is preferred from the viewpoint of industrial availability, and methyl methacrylate is particularly preferred from the viewpoint of suppressing a decrease in heat resistance.

[0038] In this embodiment, the content of the (meth)acrylic acid ester monomer unit (a1-2) relative to the total amount of the styrene-unsaturated carboxylic acid resin (A) is, for example, preferably in the range of 0 to 50 mass%, more preferably 1 to 20 mass%, even more preferably 2 to 17 mass%, still more preferably 3 to 12 mass%, and even more preferably 4 to 10 mass%.

[0039] <Preferable form of styrene-unsaturated carboxylic acid resin (A)> The styrene-unsaturated carboxylic acid resin (A) of this embodiment may be a multicomponent polymer containing (meth)acrylic acid monomer units (a1-1) and (meth)acrylic acid ester monomer units (a1-2). That is, the styrene-unsaturated carboxylic acid resin (A) of this embodiment may be a binary copolymer of the styrene monomer (1) and the (meth)acrylic acid monomer units (a1-1), or a ternary copolymer in which the styrene monomer (1), the (meth)acrylic acid monomer units (a1-1), and the (meth)acrylic acid ester monomer units (a1-2) are copolymerized. This further improves the compatibility with the (meth)acrylic resin (B), improves the surface hardness, or improves the mechanical strength.

[0040] In particular, when the improvement of heat resistance and surface hardness is important, the styrene-unsaturated carboxylic acid resin (A) preferably contains a (meth)acrylic acid monomer unit (a1-1). In particular, when the improvement of appearance and mechanical strength is important, the styrene-unsaturated carboxylic acid resin (A) preferably contains a (meth)acrylic acid ester monomer unit (a1-2). Furthermore, when the improvement of compatibility with the (meth)acrylic resin (B) and high compatibility with a mixture of the resin (B) are important, the styrene-unsaturated carboxylic acid resin (A) is preferably a copolymer containing a styrene monomer (1), a (meth)acrylic acid monomer unit (a1-1), and a (meth)acrylic acid ester monomer unit (a1-2), and more preferably a ternary copolymer in which the styrene monomer (1), the (meth)acrylic acid monomer unit (a1-1), and the (meth)acrylic acid ester monomer unit (a1-2) are copolymerized.

[0041] In addition, when an unsaturated carboxylic acid ester monomer unit such as a (meth)acrylic acid ester monomer unit (a1-2) is arranged adjacent to an unsaturated carboxylic acid monomer unit such as a (meth)acrylic acid unit (a1-1) in a polymer chain, an effect such as suppressing a crosslinking reaction between unsaturated carboxylic acids can be obtained. In the case where the styrene-unsaturated carboxylic acid resin (A) in this embodiment has a styrene-based monomer unit (1), a (meth)acrylic acid monomer unit (a1-1), and a (meth)acrylic acid ester monomer unit (a1-2), it is preferable that the content of the (meth)acrylic acid monomer unit (a1-1) is 2 to 30 mass% and the content of the (meth)acrylic acid ester monomer unit (a1-2) is 0 to 20 mass% relative to the total amount of the styrene-unsaturated carboxylic acid resin (A), and more preferably, the content of the (meth)acrylic acid monomer unit (a1-2) is 0 to 20 mass%. The content of (meth)acrylic acid ester monomer unit (a1-1) is 2 to 30 mass%, and the content of (meth)acrylic acid ester monomer unit (a1-2) is 1 to 20 mass%, more preferably, the content of (meth)acrylic acid ester monomer unit (a1-1) is 5 to 25 mass%, and the content of (meth)acrylic acid ester monomer unit (a1-2) is 1.5 to 17 mass%, and even more preferably, the content of (meth)acrylic acid ester monomer unit (a1-1) is 2 to 20 mass%, and the content of (meth)acrylic acid ester monomer unit (a1-2) is 2 to 13 mass%. By suppressing the content of (meth)acrylic acid ester monomer unit (a1-2) to 20 mass% or less, a composition having excellent fluidity during molding processing can be obtained.

[0042] <Other monomers (a2)> The styrene-unsaturated carboxylic acid resin (A) in this embodiment may further have other monomer units (a2) other than the above-mentioned styrene monomer units (1) and unsaturated carboxylic acid monomer units (a1) (including (meth)acrylic acid monomer units (a1-1) and / or (meth)acrylic acid ester monomer units (a1-2)).

[0043] That is, in this embodiment, the other monomer unit (a2) may be copolymerized with a monomer other than the two monomers shown above, without any particular limitation, as long as it is copolymerizable with the styrene-based monomer (1) and the unsaturated carboxylic acid-based monomer unit (a1) (including the (meth)acrylic acid monomer unit (a1-1) and / or the (meth)acrylic acid ester monomer unit (a1-2)), within the scope not impairing the effects of the invention.

[0044] For example, examples of the other monomers (a2) other than the three monomers shown above include maleic anhydride, maleic acid, fumaric acid, itaconic acid, (meth)acrylonitrile, dimethyl maleate, dimethyl fumarate, diethyl fumarate, ethyl fumarate, maleimide, and nucleus-substituted maleimide.

[0045] In the present embodiment, when the styrene-unsaturated carboxylic acid resin (A) contains the other monomer (a2), the content of the other monomer (a2) relative to the total amount of the styrene-unsaturated carboxylic acid resin (A) is preferably 0 to 12 mass%, more preferably 0 to 5 mass%, and even more preferably 2 mass% or less.

[0046] <Characteristics of styrene-unsaturated carboxylic acid resin (A)> In the styrene-unsaturated carboxylic acid resin (A) in this embodiment, the contents of the styrene-based monomer units (1), the unsaturated carboxylic acid-based monomer units (a1) (including the (meth)acrylic acid monomer units (a1-1) and the (meth)acrylic acid ester monomer units (a1-2)) and the other monomer units (a2) can be quantified using a calibration curve prepared by using a resin in which each monomer unit is known, using pyrolysis GC / MS.

[0047] The melt flow rate of the styrene-unsaturated carboxylic acid resin (A) in this embodiment at 200°C may be preferably 0.3 to 3.0, more preferably 0.4 to 2.5, and even more preferably 0.4 to 2.0. When the melt flow rate is 0.3 or more, it is preferable from the viewpoint of fluidity, and when it is 3.0 or less, it is preferable from the viewpoint of mechanical strength of the resin. In the present disclosure, the melt flow rate is a value measured at 200°C under a load of 49N in accordance with ISO 1133.

[0048] The weight average molecular weight (Mw) of the styrene-unsaturated carboxylic acid resin (A) in this embodiment is preferably 100,000 to 400,000, more preferably 120,000 to 320,000. When the weight average molecular weight is 100,000 to 350,000, a resin having excellent practical balance between impact strength and fluidity can be obtained. The weight average molecular weight and number average molecular weight can be measured by gel permeation chromatography in terms of standard polystyrene. The number average molecular weight (Mn) of the styrene-unsaturated carboxylic acid resin (A) is preferably 40,000 to 150,000, more preferably 50,000 to 120,000.

[0049] The Vicat softening temperature of the styrene-unsaturated carboxylic acid resin (A) in this embodiment is preferably 105 to 140°C, more preferably 107 to 135°C, even more preferably 108 to 130°C, and even more preferably 115°C to 125°C. By making the Vicat softening temperature of the styrene-unsaturated carboxylic acid resin (A) 105°C or higher, the heat resistance of the composition can be improved, and by making it 140°C or lower, it becomes easy to knead with the (meth)acrylic resin (B). The Vicat softening temperature in this specification is measured in accordance with ISO 306 (50N, heating rate 50°C / hour).

[0050] <Method for producing styrene-unsaturated carboxylic acid resin (A)> The method for producing the styrene-unsaturated carboxylic acid resin (A) of this embodiment will be described below. The method for producing the styrene-unsaturated carboxylic acid resin (A) of the present embodiment preferably includes a step of mixing a styrene monomer (1), an unsaturated carboxylic acid monomer (a1) ((meth)acrylic acid monomer unit (a1-1) and / or (meth)acrylic acid ester monomer unit (a1-2)), and a solvent to prepare a mixed solution, a polymerization step of polymerizing the mixed solution to produce a reaction product, and a step of recovering the reaction product.

[0051] The polymerization method for the styrene-unsaturated carboxylic acid resin (A) is not particularly limited, but for example, a radical polymerization method, among which a bulk polymerization method or a solution polymerization method can be preferably used. Specifically, the polymerization method mainly comprises a polymerization step of polymerizing polymerization raw materials (monomer components) and a devolatilization step of removing volatile matters such as unreacted monomers and polymerization solvent from the polymerization product.

[0052] In this embodiment, when the polymerization raw material is polymerized to obtain the styrene-unsaturated carboxylic acid resin (A), the polymerization raw material composition typically contains a polymerization initiator. Examples of the polymerization initiator include organic peroxides, such as peroxyketals such as 2,2-bis(t-butylperoxy)butane, 1,1-bis(t-butylperoxy)cyclohexane, and n-butyl-4,4-bis(t-butylperoxy)valerate, dialkyl peroxides such as di-t-butyl peroxide, t-butylcumyl peroxide, and dicumyl peroxide, diacyl peroxides such as acetyl peroxide and isobutyryl peroxide, peroxydicarbonates such as diisopropyl peroxydicarbonate, peroxyesters such as t-butylperoxyacetate, ketone peroxides such as acetylacetone peroxide, and hydroperoxides such as t-butyl hydroperoxide. Of these, 1,1-bis(t-butylperoxy)cyclohexane is preferred from the viewpoints of decomposition rate and polymerization rate.

[0053] In this embodiment, a chain transfer agent may be used as necessary during polymerization of the styrene-unsaturated carboxylic acid resin (A). Examples of the chain transfer agent include α-methylstyrene linear dimer, n-dodecyl mercaptan, t-dodecyl mercaptan, and n-octyl mercaptan.

[0054] As the polymerization method of the styrene-unsaturated carboxylic acid resin (A), solution polymerization using a polymerization solvent can be adopted. As the polymerization solvent, aromatic solvents such as toluene, ethylbenzene, propylbenzene, butylbenzene, etc. are preferable, and a solvent system in which the solubility of the styrene-unsaturated carboxylic acid resin (A) is adjusted by combining polar solvents such as alcohols or ketones as necessary may be used.

[0055] In this embodiment, the polymerization solvent is preferably used in the range of 3 to 35 parts by mass, more preferably 5 to 30 parts by mass, relative to 100 parts by mass of the total monomers constituting the styrene-unsaturated carboxylic acid resin (A). If the polymerization solvent exceeds 35 parts by mass relative to 100 parts by mass of the total monomers, the polymerization rate decreases and the molecular weight of the resulting resin also decreases, so that the mechanical strength of the resin tends to decrease. In addition, if the polymerization solvent is less than 3 parts by mass, it may be difficult to control the heat removal during polymerization. It is preferable to add the polymerization solvent in a ratio of 3 to 35 parts by mass relative to 100 parts by mass of the total monomers, because this makes it easier to uniformize the quality and also in terms of controlling the polymerization temperature.

[0056] Furthermore, when the monohydric alcohol (C) having 10 or more carbon atoms, which is an optional component of the styrene-based resin composition of this embodiment, is added from the polymerization system, it is preferable to add the (C) component in a proportion of 1 to 10 mass % relative to 100 mass % of the total polymerization solvent.

[0057] The apparatus used in the polymerization step for obtaining the styrene-unsaturated carboxylic acid resin (A) in this embodiment is not particularly limited, and may be appropriately selected according to a general polymerization method for styrene-based resins. For example, in the case of bulk polymerization, a polymerization apparatus having one or more completely mixed reactors connected thereto can be used. The devolatilization step is also not particularly limited, and in the case of bulk polymerization, polymerization is continued until the unreacted monomer is finally reduced to preferably 50% by mass or less, more preferably 40% by mass or less, and devolatilization treatment is performed by a known method in order to remove volatile matters such as the unreacted monomer. For example, a normal devolatilization apparatus such as a flash drum, a twin-screw devolatilizer, a thin film evaporator, or an extruder can be used, but a devolatilization apparatus with a small retention portion is preferred. The temperature of the devolatilization treatment is usually about 190 to 280° C., and more preferably 190 to 260° C. from the viewpoint of suppressing decomposition. The pressure of the devolatilization treatment is usually about 0.13 to 4.0 kPa, preferably 0.13 to 3.0 kPa, and more preferably 0.13 to 2.0 kPa. As a method for removing volatile matters, for example, a method of removing volatile matters by reducing pressure under heating, or a method of removing volatile matters through an extruder or the like designed for the purpose of removing volatile matters is preferable.

[0058] "(Meth)acrylic resin (B)" The styrene-based resin composition in this embodiment contains more than 0 mass% and 65 mass% or less of a (meth)acrylic resin (B) (also simply referred to as resin (B)) with respect to the total amount of the styrene-based resin composition. The (meth)acrylic resin (B) has a (meth)acrylic acid ester monomer unit (b1). The (meth)acrylic acid ester monomer unit (b1) includes a (meth)acrylic acid ester monomer unit (b1-0) in which the ester substituent has 1 carbon atom, a (meth)acrylic acid ester monomer unit (b1-1) in which the ester substituent has 2 to 10 carbon atoms, and a (meth)acrylic acid ester monomer unit (b1-2) in which the ester substituent has more than 10 carbon atoms. In the (meth)acrylic resin (B) of this embodiment, the content of the (meth)acrylic acid ester monomer unit (b1-1) contained in the (meth)acrylic acid ester monomer unit (b1) in the (meth)acrylic resin (B) is more than 35 mass% based on the total amount of the (meth)acrylic resin (B). By containing a predetermined amount of the (meth)acrylic resin (B), the low-temperature strength of the styrene-based resin composition is improved. In this specification, the (meth)acrylic resin (B) is a general term for a resin in which the content of (meth)acrylic acid ester monomer units (b1-1) contained in the (meth)acrylic resin (B) is more than 35 mass% based on the total amount of the (meth)acrylic resin (B). On the other hand, the acrylic resin (H) described later is a resin in which the content of (meth)acrylic acid ester monomer units (b1-1) contained in the acrylic resin (H) is Acrylic resin (H) A general term for resins that make up 35% by mass or less of the total amount. The (meth)acrylic acid ester monomer unit (b1-1) is an essential component of the (meth)acrylic acid ester monomer unit (b1), and the number of carbon atoms of the ester substituent is 2 to 10. The (meth)acrylic acid ester monomer unit (b1-1) is preferably represented by the above general formula (1) like the (meth)acrylic acid ester monomer (a1-2), and in the (meth)acrylic acid ester monomer unit (b1-1) represented by the general formula (1), the ester substituent is R 2 This refers to.

[0059] In the present embodiment, the number average molecular weight (Mn), weight average molecular weight (Mw), and Z average molecular weight (Mz) of the (meth)acrylic resin (B), and the proportion of high molecular weight components having a molecular weight of 1,000,000 or more in the styrene resin composition are values ​​calculated in terms of standard polystyrene measured using gel permeation chromatography (GPC), as described in the Examples section below.

[0060] The content of the (meth)acrylic resin (B) relative to the total amount (100 mass%) of the styrene-based resin composition of this embodiment is more than 0 mass% and 65 mass% or less, more preferably 3 mass% or more and 49 mass% or less, even more preferably 5 mass% or more and 39 mass% or less, still more preferably 7 mass% or more and 29 mass% or less, and most preferably 9 mass% or more and 21 mass% or less. In particular, by making the content of the (meth)acrylic resin (B) 5 mass% or more and 39 mass% or less, it is possible to suppress the deterioration of the heat resistance improved by the styrene-unsaturated carboxylic acid-based resin (A).

[0061] The monomer unit constituting the (meth)acrylic resin (B) of this embodiment contains a (meth)acrylic acid ester monomer unit (b1), and is preferably a repeating unit containing a (meth)acrylic acid monomer unit (b2) and a (meth)acrylic acid ester monomer unit (b1), or a repeating unit containing two or more types of (meth)acrylic acid ester monomer units (b1), and more preferably a repeating unit containing two or more types of (meth)acrylic acid ester monomer units (b1).

[0062] In this embodiment, the upper limit of the total content of the (meth)acrylic acid ester monomer unit (b1) and the (meth)acrylic acid monomer unit (b2) relative to the total amount of the (meth)acrylic resin (B) is preferably 100% by mass or less, 99% by mass or less, 98% by mass or less, 80% by mass or less, 75% by mass or less, and 65% by mass or less in that order. The lower limit of the content is preferably 45% by mass or more, 49% by mass or more, 51% by mass or more, 56% by mass or more, 60% by mass or more, and 67% by mass or more in that order. The total content of the (meth)acrylic acid ester monomer unit (b1) and the (meth)acrylic acid monomer unit (b2) can be any combination of the above upper limit and the above lower limit.

[0063] The (meth)acrylic acid ester monomer unit (b1) and the (meth)acrylic acid monomer unit (b2) of this embodiment will be described below. -(Meth)acrylic acid ester monomer (b1)- The (meth)acrylic acid ester monomer unit (b1) constituting the (meth)acrylic resin (B) of this embodiment includes a methacrylic acid ester monomer unit and an acrylic acid ester monomer unit. In addition, examples of the (meth)acrylic acid ester monomer (b1) include methyl acrylate, ethyl acrylate, (n-butyl) acrylate, (2-ethylhexyl) acrylate, (n-octyl) acrylate, benzyl acrylate, methyl methacrylate, butyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, (2-ethylhexyl) methacrylate, (n-octyl) methacrylate, and benzyl methacrylate, and methyl acrylate, (n-butyl) acrylate, (2-ethylhexyl) acrylate, and methyl methacrylate are preferred from the viewpoint of industrial availability and low cost. The (meth)acrylic acid ester monomers (b1) can be used alone or in mixture, and it is preferable to use a combination of two kinds of (meth)acrylic acid ester monomers.

[0064] -(meth)acrylic acid ester monomer unit (b1-1) having an ester substituent with 2 to 10 carbon atoms The (meth)acrylic resin (B) of this embodiment contains (meth)acrylic acid ester monomer units (b1-1) whose ester substituent has 2 to 10 carbon atoms in an amount of more than 35 mass% based on the total amount of the (meth)acrylic resin (B). By containing a predetermined amount of (meth)acrylic acid ester monomer units (b1-1) whose ester substituent has 2 to 10 carbon atoms in the (meth)acrylic resin (B), an effect of improving the low-temperature strength of the styrene-based resin composition is imparted.

[0065] The lower limit of the content of the (meth)acrylic acid ester monomer unit (b1-1) having 2 to 10 carbon atoms in the ester substituent is preferably 37 mass% or more, 39 mass% or more, 41 mass% or more, 43 mass% or more, 45 mass% or more, 47 mass% or more, 49 mass% or more, 51 mass% or more, 53 mass% or more, 55 mass% or more, 57 mass% or more, and 59 mass% or more, in that order, relative to the total amount of the (meth)acrylic resin (B); and the upper limit is preferably about 100 mass% or less, less than 100 mass%, 95 mass% or less, 90 mass% or less, 85 mass% or less, 80 mass% or less, 75 mass% or less, 72 mass% or less, 70 mass% or less, 68 mass% or less, 66 mass% or less, 64 mass% or less, and 62 mass% or less, in that order. The content of the (meth)acrylic acid ester monomer units (b1-1) having an ester substituent with 2 to 10 carbon atoms can be within any combination of the above upper and lower limits. The content of the (meth)acrylic acid ester monomer units (b1-0) having an ester substituent with one carbon atom is preferably 23 to 61 mass%, more preferably 36 to 56 mass%, and even more preferably 30 to 46 mass%. The content of the (meth)acrylic acid ester monomer units (b1-2) having an ester substituent with more than 10 carbon atoms is preferably 0 to 14 mass%, and more preferably 0 to 5 mass%.

[0066] A preferred (meth)acrylic resin (B) of this embodiment is preferably 28 to 62 mass% of (meth)acrylic acid ester monomer units (b1-0) having an ester substituent with 1 carbon atom, 38 to 72 mass% of (meth)acrylic acid ester monomer units (b1-1) having an ester substituent with 2 to 10 carbon atoms, and 0 to 10 mass% of (meth)acrylic acid ester monomer units (b1-2) having an ester substituent with more than 10 carbon atoms, relative to the total amount of the (meth)acrylic resin (B). More preferably, the preferred (meth)acrylic resin (B) is 32 to 52 mass% of (meth)acrylic acid ester monomer units (b1-0) having an ester substituent with 1 carbon atom, 48 to 68 mass% of (meth)acrylic acid ester monomer units (b1-1) having an ester substituent with 2 to 10 carbon atoms, and 0 to 5 mass% of (meth)acrylic acid ester monomer units (b1-2) having an ester substituent with more than 10 carbon atoms, relative to the total amount of the (meth)acrylic resin (B).

[0067] -(Meth)acrylic acid monomer (b2)- In this embodiment, the (meth)acrylic acid monomer (b2) may be acrylic acid or methacrylic acid. In this embodiment, the upper limit of the content of the (meth)acrylic acid monomer unit (b2) relative to the total amount of the (meth)acrylic resin (B) is preferably less than 60% by mass, 58% by mass or less, 45% by mass or less, 35% by mass or less, and 25% by mass or less, in that order. The lower limit of the content is preferably 0% by mass or more, 0.5% by mass or more, 1% by mass or more, 2% by mass or more, 5% by mass or more, and 10% by mass or more, in that order. The content of the (meth)acrylic acid monomer unit (b2) can be any combination of the above upper limit and the above lower limit.

[0068] <Preferable form of (meth)acrylic resin (B)> A preferred (meth)acrylic resin (B) of the present embodiment is preferably a binary or ternary copolymer, and is a methacrylic acid ester-acrylic acid ester copolymer obtained by copolymerizing a methacrylic acid ester species (methacrylic acid ester monomer unit) with an acrylic acid ester species (acrylic acid ester monomer unit), and is preferably a copolymer containing 35 to 75 mass% of the acrylic acid ester species based on the total amount of the methacrylic acid ester-acrylic acid ester copolymer, more preferably a copolymer containing 40 to 70 mass% of the acrylic acid ester species, and even more preferably a copolymer containing 46 to 67 mass% of the acrylic acid ester species.

[0069] In addition, the (meth)acrylic resin (B) in this embodiment is preferably a methyl methacrylate-n-butyl acrylate copolymer, a methyl methacrylate-2-ethylhexyl acrylate copolymer, or a methyl methacrylate-n-butyl acrylate-2-ethylhexyl acrylate copolymer.

[0070] The arrangement of the monomer units in the (meth)acrylic resin (B) of this embodiment, i.e., the classification of the copolymer of the (meth)acrylic resin (B) includes random copolymers, alternating copolymers, gradient copolymers, block copolymers, and graft copolymers. From the viewpoint of improving low-temperature strength, gradient copolymers, block copolymers, and graft copolymers are preferred, and block copolymers are particularly preferred because they are easy to impart thermal duality.

[0071] In the case where the (meth)acrylic resin (B) of the present embodiment is a block copolymer, the copolymer block constituting the (meth)acrylic resin (B) is preferably composed of a methacrylic polymer block (B-B1) in which the content of methyl methacrylate monomer in the copolymer block is 90% by mass or more, and an acrylic polymer block (B-B2) in which the content of acrylic acid ester monomer unit in the copolymer block is 90% by mass or more. The arrangement of the copolymer block may be, for example, a diblock type such as (B-B1)-(B-B2), a triblock type represented by (B-B1)-(B-B2)-(B-B1), or (B-B2)-(B-B1)-(B-B2), etc., but from the viewpoint of improving low-temperature strength, the triblock type represented by (B-B1)-(B-B2)-(B-B1) is preferable because it can impart thermal duality.

[0072] In the (meth)acrylic resin (B) of this embodiment, the content of the (meth)acrylic acid ester monomer unit (b1) in the (meth)acrylic resin (B) is more than 40% by mass, preferably 50.0 to 100% by mass, more preferably 53.0 to 99.5% by mass, even more preferably 60.0 to 98.5% by mass, and even more preferably 70 to 98.0% by mass, based on the total amount of the (meth)acrylic resin (B). In particular, by making the content of the (meth)acrylic acid ester monomer (b1) within the range of 70 to 100% by mass, the resin can withstand kneading extrusion and molding with other resins at 300°C or less. Therefore, a significant decrease in heat resistance when the styrene-(meth)acrylic acid resin (A) and the (meth)acrylic resin (B) are mixed can be suppressed. As the type of (meth)acrylic acid ester monomer (b1), two or more types selected from methyl acrylate, methyl methacrylate, n-butyl acrylate, and 2-ethylhexyl acrylate are preferred, because they are heat resistant, industrially readily available, and inexpensive.

[0073] <Other monomers (b3)> The (meth)acrylic resin (B) of this embodiment may further have other monomer units (b3) other than the above-mentioned (meth)acrylic acid monomer units (b2) and (meth)acrylic acid ester monomer units (b1). That is, the other monomers (b3) may be copolymerized with monomers other than the above-mentioned monomers without any particular limitation as long as they are copolymerizable with the (meth)acrylic acid monomer (b2) and / or the (meth)acrylic acid ester monomer (b1) and do not impair the effects of the invention. For example, other monomers (b3) other than the above-mentioned monomers include styrene, maleic anhydride, maleic acid, fumaric acid, itaconic acid, dimethyl maleate, dimethyl fumarate, diethyl fumarate, ethyl fumarate, maleimide, and nucleus-substituted maleimide.

[0074] In this embodiment, the content of the other monomer unit (b3) is preferably 0 to 60 mass%, more preferably 0 to 50 mass%, and further preferably 0 to 55 mass%, based on the total amount of the (meth)acrylic resin (B).

[0075] The weight average molecular weight (Mw) of the (meth)acrylic resin (B) of this embodiment is preferably 40,000 to 1,000,000, more preferably 46,000 to 900,000, even more preferably 56,000 to 300,000, and even more preferably 60,000 to 200,000. By making the weight average molecular weight (Mw) of the (meth)acrylic resin (B) 40,000 or more, it is possible to impart strength when kneaded with the styrene-unsaturated carboxylic acid resin (A), and by making the weight average molecular weight (Mw) 1,000,000 or less, it is possible to suppress the viscosity difference with the styrene-unsaturated carboxylic acid resin (A), and it is possible to satisfactorily disperse the (meth)acrylic resin (B) in the styrene resin composition, and it is possible to suppress the generation of unmelted matter derived from the (meth)acrylic resin (B), and it is possible to obtain a molded product such as a foamed extruded sheet having a good appearance using the composition.

[0076] The styrene-based resin composition of the present embodiment may contain a high molecular weight component of 1 million or more. When the styrene-based resin composition contains a high molecular weight component of 1 million or more, the decrease in heat resistance and rigidity is further suppressed, and moldability is improved. The proportion of the high molecular weight component of 1 million or more contained in the styrene-based resin composition is preferably 5.0 mass% or less with respect to the total amount of the styrene-based resin composition.

[0077] In addition, as a method for controlling the content of high molecular weight components having a molecular weight of 1 million or more to 5.0 mass% or less, when polymerizing the (meth)acrylic acid ester monomer (b1), control can be performed by adjusting the type and amount of the (meth)acrylic acid ester monomer (b1), the type and amount of the chain transfer agent, the reaction temperature, the residence time, the type and amount of the polymerization initiator, the type and amount of the polymerization solvent, etc. As described above, it is more preferable that the styrene-based resin composition contains a high molecular weight component having a molecular weight of 1,000,000 or more in an amount of 0.0% by mass to 5.0% by mass based on the total amount of the styrene-based resin composition.

[0078] <Method for producing (meth)acrylic resin (B)> The method for producing the (meth)acrylic resin (B) of this embodiment is not particularly limited, but it can be produced by a process such as bulk polymerization in which the (meth)acrylic acid ester monomer (b1) and other monomers are polymerized as necessary, solution polymerization in which a solvent is added, or suspension polymerization in which an organic layer is dispersed in water using a suspending agent. When the (meth)acrylic resin (B) is obtained as a block copolymer, it is preferably produced by anionic polymerization.

[0079] "Monohydric alcohol (C) with 10 or more carbon atoms" In the present embodiment, the monohydric alcohol (C) having 10 or more carbon atoms (hereinafter also simply referred to as alcohol) is an optional component, which suppresses gelation of the styrene-unsaturated carboxylic acid resin (A) during molding, and contributes to improving the appearance of the styrene-based resin composition having a good appearance and the molded article made of the styrene-based resin composition. The content of the monohydric alcohol (C) having 10 or more carbon atoms is preferably 0.01 to 1.0 mass% relative to the total amount (100 mass%) of the styrene-based resin composition, more preferably 0.03 to 0.8 mass%, even more preferably 0.05 to 0.6 mass%, and even more preferably 0.07 to 0.5 mass%. By making the content of the monohydric alcohol (C) having 10 or more carbon atoms 0.01 mass% or more, gelation of the styrene-unsaturated carboxylic acid resin (A) during molding processing can be suppressed, and by making it 1.0 mass% or less, a decrease in heat resistance and the generation of odor can be suppressed. By setting the content of the monohydric alcohol having 10 or more carbon atoms to 0.07 to 0.5 mass %, a sufficient gel suppression effect can be obtained without particularly decreasing heat resistance.

[0080] The monohydric alcohol (C) having 10 or more carbon atoms is an alcohol having 10 or more carbon atoms and containing one hydroxyl group, and may contain heteroatoms such as oxygen or nitrogen in the carbon chain constituting the alcohol, and may contain bonds other than single bonds, such as double bonds, triple bonds, ester bonds, and amide bonds in the carbon chain. The number of carbon atoms is preferably 16 or more, more preferably 17 or more, and even more preferably 18 to 50. The monohydric alcohol having 10 or more carbon atoms may be contained in a styrene-based resin composition or a molded article made of a styrene-based resin composition. Therefore, the monohydric alcohol (C) having 10 or more carbon atoms may be present (or added) in a polymerization solution used for polymerizing the styrene-(meth)acrylic acid-based resin (A) or the (meth)acrylic resin (B), so that the monohydric alcohol (C) remains in the resin composition, which is the final product, or may be added when kneading the styrene-unsaturated carboxylic acid-based resin (A) and the (meth)acrylic resin (B) and mixed in an extruder to contain the monohydric alcohol (C).

[0081] In this embodiment, the boiling point of the monohydric alcohol (C) having 10 or more carbon atoms is preferably 260° C. or higher, more preferably 270° C. or higher, and even more preferably 290° C. or higher. If the boiling point of the alcohol is lower than 260° C., it becomes highly volatile and tends to generate an unpleasant odor during molding, etc.

[0082] The monohydric alcohol (C) having 10 or more carbon atoms is not particularly limited, but examples thereof include 1-hexadecanol, isohexadecanol, 1-octadecanol, 5,7,7-trimethyl-2-(1,3,3-trimethylbutyl)-1-octanol, isooctadecanol, 1-isoisoeicosanol, 8-methyl-2-(4-methylhexyl)-1-decanol, 2-heptyl-1-undecanol, 2-heptyl-4-methyl-1-decanol, 2-(1,5-dimethylhexyl)-(5,9-dimethyl)-1-decanol, and polyoxyethylene alkyl ethers. The polyoxyethylene alkyl ether is preferably a compound represented by the following general formula (2). [ka] (In the above general formula (2), R is an alkyl group having 12 to 20 carbon atoms, and X represents the average number of ethylene oxides added and is an integer of 1 to 15.) Specific product names of preferred alcohols include "Fine Oxocol 180" manufactured by Nissan Chemical Industries, Ltd., and "Emulgen 109P" and "Kalcol 8098" manufactured by Kao Corporation.

[0083] "Core-shell type rubber polymer particles (D)" In a preferred embodiment of the styrene-based resin composition of the present embodiment, it is preferable that the composition further contains core-shell type rubber-like polymer particles (D) (also simply referred to as core-shell particles (D)) obtained by grafting a copolymer mainly composed of (meth)acrylic acid ester monomer units (d2) onto rubber-like particles containing conjugated diene monomer units (d1). In this specification, the term "mainly composed" means that the content is 50% by mass or more of the total.

[0084] The core-shell type rubbery polymer particles (D) of this embodiment have a structure in which a rubbery particle containing a conjugated diene monomer unit (d1) forms a core, and the core is at least partially coated with a copolymer mainly composed of a (meth)acrylic acid ester monomer unit (d2).

[0085] The content of the core-shell type rubbery polymer particles (D) of this embodiment is preferably 1 to 45 mass% based on the total amount of the styrene-based resin composition, more preferably 2 to 40 mass%, even more preferably 3 to 35 mass%, still more preferably 4 to 30 mass%, and most preferably 5 to 25 mass%. By making it 1 mass% or more, it is possible to improve mechanical strength and low-temperature impact resistance, and by making it 25 mass% or less, it is possible to prevent a decrease in heat resistance and rigidity.

[0086] The conjugated diene monomer (d1) constituting the core-shell type rubbery polymer particles (D) is a diolefin having a pair of conjugated double bonds, such as 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, and 1,3-hexadiene.

[0087] The (meth)acrylic acid ester monomer unit (d2) constituting the core-shell type rubber-like polymer particle (D) includes a methacrylic acid ester monomer unit and an acrylic acid ester monomer unit. In addition, the (meth)acrylic acid ester monomer unit includes methyl acrylate, ethyl acrylate, (n-butyl) acrylate, (2-ethylhexyl) acrylate, (n-octyl) acrylate, benzyl acrylate, methyl methacrylate, butyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, (2-ethylhexyl) methacrylate, (n-octyl) methacrylate, benzyl methacrylate, etc., and methyl acrylate, (n-butyl) acrylate, and methyl methacrylate are preferred from the viewpoint of industrial availability and low cost.

[0088] The content of the conjugated diene monomer unit (d1) in the core-shell type rubbery polymer particle (D) is preferably 30 to 90 mass%, more preferably 40 to 85 mass%, even more preferably 50 to 80 mass%, and even more preferably 55 to 75 mass% based on the total amount of the core-shell type rubbery polymer particle (D). The higher the content of the conjugated diene monomer unit (d1), the greater the improvement in mechanical strength with a small amount of addition, which is preferable. On the other hand, if the content of the conjugated diene monomer unit (d1) is too high, the content of the graft copolymer mainly composed of (meth)acrylic acid ester monomer unit (d2) decreases, and the compatibility with the styrene-unsaturated carboxylic acid resin (A) decreases, which causes a decrease in the effect of improving the mechanical strength.

[0089] The content of the (meth)acrylic acid ester monomer unit (d2) in the core-shell type rubbery polymer particle (D) is preferably 10 to 40 mass%, more preferably 12 to 35 mass%, and even more preferably 15 to 25 mass% based on the total amount of the core-shell type rubbery polymer particle (D). By setting the content of the (meth)acrylic acid ester monomer (d2) in the range of 20 to 70 mass%, it is possible to ensure compatibility with the matrix polymer portion constituting the styrene-based resin composition of this embodiment, and the effect of improving the mechanical strength can be efficiently obtained. The matrix polymer portion essentially contains the resin (A) and the resin (B), and contains one or more optional components selected from the group consisting of the polymer matrix (E-1), the polymer matrix (G-1), the styrene-based elastomer (F), the acrylic resin (H), the monohydric alcohol having 10 or more carbon atoms, and optional additive components. In other words, the matrix polymer portion refers to components other than the various rubbery polymer particles contained in the styrene-based resin composition. The various rubber-like polymer particles include rubber-like polymer particles (E-2), core-shell type rubber-like polymer particles (D) and rubber-like polymer particles (G-2).

[0090] <Particle size of core-shell type rubber polymer particles (D)> The average particle size of the core-shell type rubbery polymer particles (D) is preferably 0.05 to 0.35 μm, more preferably 0.080 to 0.30 μm, even more preferably 0.10 to 0.25 μm, and still more preferably 0.15 to 0.23 μm. In particular, by setting the average particle size in the range of 0.15 to 23 μm, the effect of imparting strength to the styrene-based resin composition is excellent. In the present disclosure, the average particle size is measured from a cross-sectional observation image taken with a transmission electron microscope, as described later in the Examples section.

[0091] <Method for producing core-shell type rubbery polymer particles (D)> As a method for producing the core-shell type rubbery polymer particles (D), an emulsion polymerization method is preferred in which conjugated diene rubber latex (e.g., butadiene rubber latex) particles are produced and then copolymerized with a (meth)acrylic acid ester monomer (d2).

[0092] "Impact-resistant styrene resin (E)" In a preferred embodiment of the present invention, the styrene resin composition preferably contains an impact-resistant styrene resin (E) (also simply referred to as resin (E)). By containing an appropriate amount of the rubber-modified styrene resin (E), a styrene resin composition capable of producing a molded article having excellent strength can be obtained.

[0093] The rubber-modified styrene-based resin (E) of this embodiment may be a so-called high impact polystyrene resin (HIPS resin) obtained by dispersing particles of a rubber-like polymer (E-2) (=rubber-like polymer particles (E-2)) in a polymer matrix (E-1) of a resin consisting of a styrene-based monomer (e1) and, if necessary, other monomers (e3), and polymerizing the styrene-based monomer (e1) and / or other monomers (e3) in the presence of the rubber-like polymer (E-2). In other words, the impact-resistant styrene-based resin (E) of this embodiment contains a polymer matrix (E-1) and rubber-like polymer particles (E-2). The polymer matrix (E-1) contains a polymer obtained by polymerizing a styrene-based monomer (e1) and other monomers (e3) that are blended as necessary. That is, the polymer matrix (E-1) is composed of a styrene polymer containing styrene-based monomer units (e1) and other monomer units (e3) that are included as necessary. The rubber-like polymer particles (E-2) are particles of a rubber-like polymer (E-2) mainly composed of conjugated diene-based monomer units (e2), and the surface of the particles may be grafted with a polymer containing a styrene-based monomer unit (e1) as necessary.

[0094] The content of the impact resistant styrene resin (E) in the styrene composition of the present embodiment is preferably 0.5 to 30 mass%, more preferably 2 to 20 mass%, and even more preferably 3 to 15 mass%, based on the total amount of the styrene resin composition. By setting the content of the impact resistant styrene resin (E) in the range of 3 to 15 mass%, a styrene resin composition having better strength can be obtained.

[0095] -Rubber-like polymer particles (E-2)- In this embodiment, the rubber-like polymer (E-2) constituting the rubber-like polymer particles (E-2) in the impact-resistant styrene-based resin (E) is preferably formed from a conjugated diene-based monomer (e2), and more preferably is a polymer having a conjugated diene-based monomer unit (e2). Specific examples of the rubber-like polymer (E-2) that can be used include polybutadiene, polyisoprene, natural rubber, polychloroprene, styrene-butadiene copolymer, and acrylonitrile-butadiene copolymer, but from an industrial point of view, polybutadiene and styrene-butadiene copolymer are preferred. As the polybutadiene, high-cis polybutadiene having a high cis content, low-cis polybutadiene having a low cis content, or both of these can be used. The structure of the styrene-butadiene copolymer may be a random structure, a block structure, or a combination of these. These rubber-like polymers may be used alone or in combination of two or more. Saturated rubber obtained by hydrogenating butadiene rubber can also be used.

[0096] In the present specification, the term "conjugated diene monomer" is a general term for the above-mentioned conjugated diene monomer (d2), conjugated diene monomer (e1), conjugated diene monomer (f2) and conjugated diene monomer (g2). In addition, in the present specification, the term "rubber-like polymer particles" is a general term for the rubber-like polymer particles (G-2), rubber-like polymer particles (D) and rubber-like polymer particles (E-2). The conjugated diene monomer is a diolefin having a pair of conjugated double bonds among the monomer units constituting the rubber-like polymer particles, and examples thereof include 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, and 1,3-hexadiene.

[0097] In the present embodiment, the rubber-like polymer particles (E-2) preferably contain a polymer containing a styrene-based monomer unit (e1) or a polymer containing the styrene-based monomer unit (e1) and another monomer (e3) in the dispersed particles of the rubber-like polymer (E-2). The form of the inclusion is preferably a so-called salami-structured dispersed particle in which a plurality of domain phases of a polymer having a styrene-based monomer unit (e1) are contained in the rubber-like polymer (E-2).

[0098] -Other monomers (e3)- Examples of the other monomer (unit) (e3), which is an optional component of the impact resistant styrene-based resin (E) of this embodiment, include (meth)acrylic acid ester-based monomers such as methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, isopropyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, and isopropyl methacrylate. Of these, n-butyl acrylate and methyl methacrylate are preferred from the viewpoint of industrial availability.

[0099] In this embodiment, the content of the other monomer (unit) (e3) in the impact resistant styrene-based resin (E) is preferably 70 mass % or less, and more preferably 60 mass % or less, based on the total amount of the impact resistant styrene-based resin (E).

[0100] <Content of conjugated diene monomer unit (e2)> In this embodiment, the content of the conjugated diene monomer unit (e2) in the impact resistant styrene resin (E) is preferably 0.5 to 15.0 mass%, more preferably 1.0 to 13.0 mass%, and even more preferably 2.0 to 12.0 mass% based on the total amount of the impact resistant styrene resin (E). The content of the conjugated diene monomer unit (e2) in the impact resistant styrene resin (E) and the styrene resin composition can be measured by the procedure described in the Examples section below or a method equivalent thereto.

[0101] <Average particle size of rubber-like polymer particles (E-2)> The rubber-like polymer (E-2) which is the rubber component in the impact-resistant styrene-based resin (E) in this embodiment is present as particles of the rubber-like polymer (E-2) in the styrene-based resin composition. In this case, the average particle size of the rubber-like polymer particles (E-2) is preferably 0.3 to 5.0 μm, more preferably 0.5 to 4.0 μm, and even more preferably 0.7 to 3.0 μm. The impact-resistant styrene-based resin (E) is obtained by polymerizing a styrene-based monomer (e1) in a reactor equipped with a stirrer in the presence of the rubber-like polymer particles (E-2), and the average particle size of the rubber-like polymer particles (E-2) can be adjusted by the number of revolutions of the stirrer, the molecular weight of the rubber-like polymer (E-2) used, and the like. In the present disclosure, the average particle size of the rubber-like polymer particles (E-2) is a value measured from a cross-sectional observation image by a transmission electron microscope, as shown in the Examples section described later. The rubber-like polymer particles (E-2) are stretched during foaming in the second foamed sheet described below, and the particle size increases by about 150 to 400%.

[0102] In this embodiment, the melt flow rate of the impact resistant styrene resin (E) at 200°C is preferably 0.5 to 10.0 g / 10 min, more preferably 0.7 to 8.0 g / 10 min, and even more preferably 1.0 to 7.0 g / 10 min. If the melt flow rate is in the range of 0.5 to 10.0 g / 10 min, the mixture with the styrene-(meth)acrylic acid resin (A) and the (meth)acrylic resin (B) is good, and the mechanical strength is also good. In the present disclosure, the melt flow rate is a value measured at 200°C and a load of 49 N in accordance with ISO 1133.

[0103] <Production method of impact-resistant styrene resin (E)> The method for producing the impact-resistant styrene-based resin (E) of this embodiment is not particularly limited, but it can be produced by bulk polymerization (or solution polymerization) in which a styrene-based monomer (e1) and, if necessary, other monomers (e3) and a solvent are polymerized in the presence of a rubber-like polymer (E-2), bulk-suspension polymerization that transitions to suspension polymerization during the reaction, or emulsion graft polymerization in which a styrene-based monomer (e1) is polymerized in the presence of latex particles that are a rubber-like polymer (E-2). In bulk polymerization, the rubber-like polymer (E-2), the styrene-based monomer (e1), and, if necessary, other monomers (e3), an organic solvent, an organic peroxide, and / or a chain transfer agent are continuously supplied to a polymerization apparatus that is composed of a complete mixing reactor or a tank reactor and a plurality of tank reactors connected in series, to produce the resin.

[0104] "Styrene-based elastomer (F)" In a preferred embodiment of this embodiment, the styrene-based resin composition further contains a styrene-based elastomer (F) (also simply referred to as elastomer (F)). The styrene-based elastomer (F) used in the styrene-based resin composition of the present invention is a block copolymer having a hard block of a styrene-based monomer (unit) (f1) and a soft block of a conjugated diene-based monomer (unit) (f2). As the elastomer (F), a block copolymer having a hard block of a styrene-based monomer (unit) (f1) and a soft block of a butadiene monomer unit is more preferred. The styrene monomer (f1) may be the same as the styrene monomer (1) described above. The conjugated diene monomer (f2) may be the same as the conjugated diene monomer (d2) and the conjugated diene monomer (e2) described above.

[0105] Examples of the chain structure of the block copolymer of the styrene-based elastomer (F) of this embodiment include a styrene-based monomer (f1)-butadiene diblock type, a styrene-based monomer (f1)-butadiene-styrene-based monomer (f1) triblock type, and a butadiene-styrene-based monomer (f1)-butadiene triblock type. From the viewpoint of improving mechanical strength, the styrene-based monomer (f1)-butadiene-styrene-based monomer (f1) triblock type is preferred.

[0106] In this embodiment, the content of the styrene-based monomer unit (f1) and the conjugated diene-based monomer unit (f2) constituting the styrene-based elastomer (F) is preferably 20 to 70 mass% of the styrene-based monomer unit (f1) relative to the total amount of the styrene-based elastomer (F), more preferably 25 to 45 mass% of the styrene-based monomer unit (f1), and the content of the conjugated diene-based monomer unit (f2) is the remainder of 100 mass%. If the content of the styrene-based monomer unit (f1) is 25 to 45%, the dispersibility in the styrene-unsaturated carboxylic acid-based resin (A) is appropriately improved, and a product excellent in mechanical strength and appearance can be obtained. Methods for producing the styrene-based elastomer (F) such as styrene-butadiene elastomer include radical polymerization, anionic polymerization, and polymer reaction methods, with the anionic polymerization method being preferred from the industrial viewpoint.

[0107] In this embodiment, when the content of the conjugated diene monomer (f2) in the styrene-based elastomer (F) exceeds 50% by mass, the content of the styrene-based elastomer (F) in the styrene-based composition of this embodiment may be preferably 0.5 to 15% by mass, more preferably 1 to 12% by mass, and even more preferably 2 to 7% by mass, based on the total amount of the styrene-based resin composition. On the other hand, when the content of the conjugated diene monomer unit (f2) in the styrene-based elastomer (F) is 50% by mass or less, the content of the styrene-based elastomer (F) in the styrene-based composition is preferably 3 to 30% by mass, more preferably 5 to 20% by mass, and even more preferably 7 to 15% by mass, based on the total amount of the styrene-based resin composition. By setting it in the above range, it is possible to suppress the decrease in heat resistance and improve the mechanical strength when added to the styrene-based resin composition.

[0108] "(Meth)acrylonitrile-diene-styrene resin (G)" As a preferred embodiment of the present invention, the styrene-based resin composition of the present invention preferably further contains a (meth)acrylonitrile-diene-styrene-based resin (G) (also simply referred to as resin (G)) containing a (meth)acrylonitrile-based monomer unit (g3), a conjugated diene-based monomer unit (g2) and a styrene-based monomer unit (g1). When the styrene-based resin composition contains an appropriate amount of the (meth)acrylonitrile-diene-styrene-based resin (G), a styrene-based resin composition capable of forming a molded article having superior low-temperature strength can be obtained. The (meth)acrylonitrile-diene-styrene-based resin (G) of the present embodiment refers to a resin obtained by dispersing rubber-like polymer particles (=rubber-like polymer particles (G-2)) in which (meth)acrylonitrile-based monomer units (g3) and styrene-based monomers (g1) are graft-polymerized with conjugated diene-based monomer units (g2) as a main component in a polymer matrix (G-1) containing a copolymer obtained by polymerizing (meth)acrylonitrile-based monomer units (g3), styrene-based monomers (g1), and other monomer components as necessary, and other resins blended as necessary, and may be, for example, a so-called ABS resin.

[0109] In other words, the (meth)acrylonitrile-diene-styrene resin (G) of this embodiment contains a polymer matrix (G-1) and rubber-like polymer particles (G-2). The polymer matrix (G-1) contains a copolymer obtained by polymerizing (meth)acrylonitrile-based monomer units (g3), styrene-based monomers (g1), and other monomer components blended as necessary, and other resins blended as necessary. The rubber-like polymer particles (G-2) are particles of a rubber-like polymer mainly composed of conjugated diene-based monomer units (g2).

[0110] In this specification, the term "mainly composed" means that it occupies 50% by mass or more of the whole. Therefore, for example, a rubber-like polymer particle mainly composed of butadiene-based monomer units (g2) means that the butadiene-based monomer units (g2) occupy 50% by mass or more of the whole rubber-like polymer particle (G-2).

[0111] Examples of the styrene monomer (g1) include styrene, α-methylstyrene, o-methylstyrene, p-methylstyrene, ethylstyrene, pt-butylstyrene, and vinylnaphthalene. Among these, styrene is preferred from the viewpoint of versatility. The styrene monomer (g1) may be used alone or in combination of two or more kinds.

[0112] Examples of the conjugated diene monomer unit (g2) of this embodiment include 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, and 1,3-hexadiene, and 1,3-butadiene is preferred from an industrial viewpoint. The conjugated diene monomer unit (g2) may be used alone or in combination of two or more kinds.

[0113] Examples of the (meth)acrylonitrile-based monomer unit (g3) in this embodiment include acrylonitrile units and methacrylonitrile units. Among these, acrylonitrile units are preferred from an industrial viewpoint. The (meth)acrylonitrile-based monomer unit (g3) may be used alone or in combination of two or more kinds.

[0114] The mass ratio of the (meth)acrylonitrile monomer unit (g3) to the styrene monomer unit (g1) in the polymer matrix (G-1) constituting the (meth)acrylonitrile-diene-styrene resin (G) of this embodiment is preferably (meth)acrylonitrile monomer unit (g3) / styrene monomer unit (g1)=5 / 95 to 40 / 60, more preferably 10 / 90 to 35 / 65, more preferably 15 / 85 to 30 / 70, and most preferably 20 / 80 to 25 / 75. In particular, by making the mass ratio in the range of 20 / 80 to 30 / 70, the compatibility with the (meth)acrylic resin (B) is excellent, and the effect of improving the mechanical strength when added to a styrene resin composition is high.

[0115] The content of the rubber-like polymer particles (G-2) mainly composed of the conjugated diene monomer unit (g2) constituting the (meth)acrylonitrile-diene-styrene-based resin (G) of this embodiment is preferably 5 to 40 mass %, more preferably 10 to 35 mass %, and further preferably 15 to 30 mass % relative to the total amount of the (meth)acrylonitrile-diene-styrene-based resin (G). By setting the content of the rubber-like polymer particles (G-2) in the range of 5 to 40 mass %, the balance between rigidity and impact resistance is excellent when added to a styrene-based resin composition.

[0116] The average particle size of the rubber-like polymer particles (G-2) of the (meth)acrylonitrile-diene-styrene-based resin (G) of this embodiment is preferably 0.10 to 1.00 μm, more preferably 0.13 to 0.90 μm, even more preferably 0.16 to 0.70 μm, and even more preferably 0.20 to 0.50 μm. In particular, by making the average particle size in the range of 0.20 to 0.50 μm, the styrene-based resin composition has an excellent effect of improving impact resistance. In the present disclosure, the average particle size is measured from a cross-sectional observation image taken with a transmission electron microscope, as described later in the Examples section.

[0117] In addition, a preferred embodiment of the rubber-like polymer particle (G-2) may have a structure in which a solid rubber-like particle having conjugated diene monomer units (g2) as a constituent component is used as a core, and the core is coated with a polymer containing styrene monomer units (g1) and (meth)acrylonitrile monomer units (g3) so as to cover the core.

[0118] The (meth)acrylonitrile-diene-styrene-based resin (G) of the present embodiment can be produced by polymerizing a resin that is the main component of the polymer matrix (G-1) prepared in advance by radical bulk polymerization or solution polymerization, and ABS rubber-like polymer particles (G-2) prepared by graft polymerization with rubber latex, and then compounding them to prepare the resin; or, as in the case of the impact-resistant styrene-based resin (E), preparing the rubber-like polymer particles (G-2) and the polymer matrix (G-1) simultaneously. An optimal method can be selected according to need.

[0119] In the polymer matrix (G-1) of the (meth)acrylonitrile-diene-styrene resin (G) of the present embodiment, in addition to the copolymer mainly composed of the (meth)acrylonitrile monomer unit (g3) and the styrene monomer (g1), other polymers may be contained in the range of 25 mass% or less based on the total amount of the (meth)acrylonitrile-diene-styrene resin (G). For example, the heat resistance of the (meth)acrylonitrile-diene-styrene resin (G) may be improved by adding a styrene-acrylonitrile-N-phenylmaleimide copolymer or the like.

[0120] In this embodiment, the melt flow rate of the (meth)acrylonitrile-diene-styrene resin (G) at 200°C is preferably 0.2 to 7.0 g / 10 min, more preferably 0.3 to 6.0 g / 10 min, and even more preferably 0.4 to 5.0 g / 10 min. If the melt flow rate is in the range of 0.2 to 7.0 g / 10 min, the mixture with the styrene-unsaturated carboxylic acid resin (A) and the (meth)acrylic resin (B) is good, and the mechanical strength is also good. In the present disclosure, the melt flow rate is a value measured at 200°C and a load of 49 N in accordance with ISO 1133.

[0121] "Acrylic resin (H)" In a preferred embodiment of this embodiment, the styrene-based resin composition preferably contains an acrylic resin (H) (also simply referred to as resin (H)). The acrylic resin (H) is a general term for resins having more than 40 mass% of (meth)acrylic acid ester monomer units (h1). In the acrylic resin (H) of this embodiment, the content of the (meth)acrylic acid ester monomer units (b1-1) contained in the (meth)acrylic acid ester monomer units (h1) in the acrylic resin (H) is , acrylic resin (H) The acrylic resin (H) is 35% by mass or less based on the total amount. The acrylic resin (H) plays a role of improving the compatibility between the styrene-unsaturated carboxylic acid resin (A) and each of the above-mentioned resins, and in particular, plays a role of improving the compatibility between the (meth)acrylonitrile-diene-styrene resin (G) and the styrene-unsaturated carboxylic acid resin (A).

[0122] -(Meth)acrylic acid ester monomer unit (h1)- The (meth)acrylic acid ester monomer unit (h1) constituting the acrylic resin (H) of this embodiment includes a methacrylic acid ester monomer unit and an acrylic acid ester monomer unit. In addition, examples of the (meth)acrylic acid ester monomer (h1) include methyl acrylate, ethyl acrylate, (n-butyl) acrylate, (2-ethylhexyl) acrylate, (n-octyl) acrylate, benzyl acrylate, methyl methacrylate, butyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, (2-ethylhexyl) methacrylate, (n-octyl) methacrylate, and benzyl methacrylate, and from the viewpoint of industrial availability and low cost, methyl acrylate, (n-butyl) acrylate, 2-ethylhexyl acrylate, and methyl methacrylate are preferred. The (meth)acrylic acid ester monomers (h1) can be used alone or in mixture, and it is preferable to use two kinds of (meth)acrylic acid ester monomers in combination.

[0123] <Preferable form of acrylic resin (H)> A preferred acrylic resin (H) in this embodiment is preferably a binary or ternary copolymer, and is preferably a methacrylic acid ester-acrylic acid ester copolymer in which a methacrylic acid ester species (methacrylic acid ester monomer unit) and an acrylic acid ester species (acrylic acid ester monomer unit) are copolymerized, or a methacrylic acid ester-styrene copolymer.

[0124] When the acrylic resin (H) of this embodiment is a methacrylic acid ester-acrylic acid ester copolymer, the upper limit of the content of the acrylic acid ester monomer unit relative to the total amount of the methacrylic acid ester-acrylic acid ester copolymer is preferably 15% by mass or less, 14% by mass or less, 13% by mass or less, 11% by mass or less, 9% by mass or less, 7% by mass or less, 6% by mass or less, and 5% by mass or less, and the lower limit is preferably 0.1% by mass or more, 0.3% by mass or more, 0.4% by mass or more, 0.6% by mass or more, 0.8% by mass or more, 1.0% by mass or more, 1.1% by mass or more, 1.2% by mass or more, 1.3% by mass or more, 1.4% by mass or more, 1.5% by mass or more, and 1.8% by mass or more. The range of the content of the acrylic acid ester monomer unit can be arbitrarily combined with the above upper limit value and lower limit value.

[0125] The acrylic resin (H) in this embodiment is preferably a methyl methacrylate-n-butyl acrylate copolymer, a methyl methacrylate-ethyl acrylate copolymer, or a methyl methacrylate-methyl acrylate copolymer. From the viewpoint of heat resistance, a methyl methacrylate-methyl acrylate copolymer is particularly preferable.

[0126] The arrangement of the monomer units in the acrylic resin (H) of the present embodiment, i.e., the classification of the copolymerization of the acrylic resin (H) includes random copolymers, alternating copolymers, gradient copolymers, block copolymers, and graft copolymers. From the viewpoint of compatibility with the styrene-unsaturated carboxylic acid resin (A), a random copolymer is preferred.

[0127] The content of the acrylic resin (H) in the styrene-based composition of this embodiment is preferably 0.1% by mass or more, 0.5% by mass or more, 1.0% by mass or more, 5.0% by mass or more, 7.0% by mass or more, 9.0% by mass or more, 11% by mass or more, 14% by mass or more, 17% by mass or more, 18% by mass or more, 19% by mass or more, and 20% by mass or more in this order, with respect to the total amount of the styrene-based resin composition, and preferably 40% by mass or less, 37% by mass or less, 35% by mass or less, 34% by mass or less, 33% by mass or less, 32% by mass or less, 31% by mass or less, 30% by mass or less, 29% by mass or less, 28% by mass or less, 27% by mass or less, 26% by mass or less, and 25% by mass or less in this order. The range of the content of the acrylic resin (H) can be arbitrarily combined with the above upper limit value and lower limit value. In particular, by setting the content of the acrylic resin (H) to be 5.0 mass% or more and 27 mass% or less, it is possible to obtain a styrene-based resin composition having an excellent balance between mechanical strength and heat resistance while ensuring the compatibility between the styrene-unsaturated carboxylic acid-based resin (A) and other resins.

[0128] "Optional added ingredients" In addition to the above (A) to (H), the styrene-based resin composition of this embodiment can also be made into a styrene-based resin composition by blending various optional additive components that are generally used in styrene-based resins to achieve known effects. The optional additive components of this embodiment are, for example, one or more selected from the group consisting of stabilizers, higher fatty acid surfactants, antioxidants, light stabilizers, ultraviolet absorbers, lubricants, release agents, plasticizers, antiblocking agents, antistatic agents, antifogging agents, inorganic particles, and mineral oils. There is no particular restriction on the blending method, but examples include a method of adding the additives during polymerization and polymerizing them, or a method of mixing the additives in advance in a blender before melt-kneading after polymerization, and then melt-kneading with an extruder or Banbury mixer, etc.

[0129] <Antioxidants> Examples of the antioxidant include hindered phenol-based antioxidants such as octadecyl-3-(3,5-tertiary butyl-4-hydroxyphenyl)propionate and 4,6-bis(octylthiomethyl)-o-cresol (product Irganox 1076), and phosphorus-based antioxidants such as tris(2,4-di-tertiary butylphenyl)phosphite (product Irgafos 176). These stabilizers may be used alone or in combination of two or more. There is no particular restriction on the timing of addition, and it may be either the polymerization process or the devolatilization process. The stabilizer may also be mixed into the product using a mechanical device such as an extruder or a Banbury mixer. The content of the antioxidant is preferably 0.001 to 2.0 mass%, more preferably 0.01 to 1.0 mass, even more preferably 0.05 to 0.5 mass, still more preferably 0.08 to 0.4 mass, and most preferably 0.1 to 0.3 mass, when the total amount of the styrene-based resin composition is taken as 100 mass. By setting the content in the range of 0.05 to 0.5 mass, in particular, it is possible to obtain a styrene-based resin composition that achieves both low bleeding and an antioxidant effect. In particular, by using a phenol-based antioxidant in combination with a phosphorus-based antioxidant, a synergistic effect can be obtained that suppresses oxidative deterioration caused by heat history during kneading / extrusion and molding.

[0130] <Light stabilizer> The light stabilizer of the present embodiment does not have ultraviolet absorbing ability by itself, but it is a compound that has a function of capturing and detoxifying photoradicals generated by the styrene-based resin composition absorbing ultraviolet light, thereby preventing the deterioration and coloring of the styrene-based resin composition caused by radicals. As the light stabilizer, a hindered amine-based compound is preferable, and examples thereof include hindered amine-based compounds such as secondary amine type, tertiary amine type, and N-alkoxy type. The light stabilizer can be used alone or in combination of two or more types. By using a UV absorber described later in combination, a higher light resistance effect can be achieved, in other words, coloring and strength reduction after exposure due to long-term outdoor use of the styrene-based resin composition or its molded product can be suppressed, and it is preferable to add the light stabilizer to the styrene-based resin composition depending on the application. Since the light stabilizer mainly exerts its function on the resin surface where photoradicals are generated in large amounts, a low molecular type is preferable if it is to be more effective, but it is necessary to adjust the molecular weight to an appropriate level to prevent mold contamination due to excessive bleed-out. The content of the light stabilizer in this embodiment is preferably 0.001 to 2.0 mass%, more preferably 0.01 to 1.0 mass, even more preferably 0.05 to 0.5 mass, still more preferably 0.08 to 0.4 mass, and most preferably 0.1 to 0.3 mass, when the total amount of the styrene-based resin composition is taken as 100 mass. In particular, by setting the content in the range of 0.05 to 0.5 mass, a styrene-based resin composition that achieves both low bleeding and light stabilization effect can be obtained.

[0131] <Ultraviolet absorbing agent> The ultraviolet absorber of the present embodiment is a compound that absorbs ultraviolet light absorbed by the styrene-based resin composition in place of the styrene-based resin composition and converts it into heat or chemical energy, thereby suppressing the generation of photoradicals due to ultraviolet light absorption by the styrene-based resin composition and suppressing deterioration and coloring of the resin. Examples of the ultraviolet absorber include benzotriazole-based compounds, triazine-based compounds, benzophenone-based compounds, benzoate-based compounds, cyanoacrylate-based compounds, oxalic acid anilide-based compounds, malonic acid ester-based compounds, formamidine-based compounds, and salicylate-based compounds. These ultraviolet absorbers can be used alone or in combination of two or more kinds, and can be used in combination with a light stabilizer represented by a hindered amine compound or the like to achieve a higher light resistance effect, in other words, to suppress coloring and strength reduction after exposure of the styrene-based resin composition, so that they may be added to the styrene-based resin composition depending on the application. In addition, ultraviolet absorbers that can absorb ultraviolet wavelengths (250 to 350 nm) that are easily absorbed by the resin added to the styrene-based resin composition in place of the resin are preferred. Preferred examples of the ultraviolet absorber include benzotriazole-based compounds, triazine-based compounds, benzophenone-based compounds, and benzoate-based compounds.Specific examples of the ultraviolet absorber include 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2,2'-methylenebis[6-(2H-benzotriazol-2-yl)-4-tert-octylphenol, 2-(2'-hydroxy-3',5'-di-tert-amylphenyl)benzotriazole, 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole, 6-(2-benzotriazolyl)-4-tert-octyl-6'-tert-butyl-4'-methylphenyl, and 6-(2-benzotriazolyl)-4-tert-octyl-6'-tert-butyl-4'-methylphenyl. 2-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol, 2-(4,6-diphenyl-1,3,5-triazin-2-yl)-5-[2-(2-ethylhexanoyloxy)ethoxy]phenol, 2,4,6-tris(2-hydroxy-4-hexyloxy-3-methylphenyl)-1,3,5-triazine, N, N',N''-tri(m-tolyl)-1,3,5-triazine-2,4,6-triamine, 2,4,6-tris(4-butoxy-2-hydroxyphenyl)-1,3,5-triazine, 2,4-bis(2,4-dimethylphenyl)-6-(2-hydroxy-4-n-octyloxyphenyl)-1,3,5-triazine, ethylhexyltriazine, 2-(2,4-dihydroxyphenyl)-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, 2,4,6-tris(2,4-dihydroxyphenyl)-1 ,3,5-triazine, bemotodinol, 2-(2-hydroxy-4-methoxyphenyl)-4,6-diphenyl-1,3,5-triazine, 2-(2,4-dihydroxyphenyl)-4,6-diphenyl-1,3,5-triazine, 2-hydroxy-4-(octyloxy)benzophenone, 2-hydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2,4-dihydroxybenzophenone, 2,2',4,4'-tetrahydroxybenzophenone, and the like. The content of the ultraviolet absorber in this embodiment is preferably 0.001 to 2.0 mass%, more preferably 0.01 to 1.0 mass, even more preferably 0.05 to 0.5 mass, still more preferably 0.08 to 0.4 mass, and most preferably 0.1 to 0.3 mass, when the total amount of the styrene-based resin composition is taken as 100 mass. By setting the content in the range of 0.05 to 0.5 mass, in particular, it is possible to obtain a styrene-based resin composition that has both low bleeding and ultraviolet absorbing effect.

[0132] <Higher fatty acid surfactants> As a preferred aspect of this embodiment, the styrene resin composition preferably contains a higher fatty acid surfactant. The addition of a higher fatty acid surfactant not only prevents blocking of the foamed sheet, but also contributes to torque reduction between pellets and metering stability during kneading of the resin composition by adding an appropriate amount. Therefore, the content of the higher fatty acid surfactant is preferably in the range of 0.002 to 0.1 parts by mass relative to the total amount of the styrene resin composition. The above effect can be obtained, and by making the content 0.1 parts by mass or less, it is possible to prevent the surfactant from contributing as a gelling agent for the styrene-unsaturated carboxylic acid resin (A). The higher fatty acid surfactant may be added during the granulation process after polymerization of each resin, or may be added when the styrene-unsaturated carboxylic acid resin (A) and the (meth)acrylic resin (B) are mixed together. The higher fatty acid surfactant is not particularly limited, but examples thereof include stearic acid, calcium stearate, calcium stearate, and ethylene bisstearamide, with ethylene bisstearamide being preferred.

[0133] <Inorganic particles> In a preferred embodiment of the present invention, when the styrene-based resin composition is processed into a foam extrusion sheet, it is preferred to contain inorganic particles. By adding inorganic particles to the styrene-based resin composition, the composition plays a role as a foam nucleating agent during foam molding, and contributes to improving the rigidity of a molded article including the composition and the foam sheet.

[0134] Examples of the inorganic particles that can be used include kaolin, mica, silica, calcium carbonate, sodium carbonate, barium carbonate, barium sulfate, calcium sulfate, titanium oxide, aluminum oxide, clay, bentonite, talc, diatomaceous earth, etc. Among these, talc is preferred because it has a long track record of application in food packaging applications and its safety is guaranteed.

[0135] The content of the inorganic particles is preferably 0.1 to 7.0 parts by mass, more preferably 0.2 to 6.0 parts by mass, and even more preferably 0.3 to 4.0 parts by mass, when the total amount of the styrene-based resin composition is taken as 100% by mass. By setting the content in the range of 0.1 to 7.0 parts by mass, a sheet with an expansion ratio suitable for a foam sheet for food packaging can be obtained.

[0136] In this embodiment, there is no particular limitation on the method of adding the inorganic particles to the styrene-based resin composition. The inorganic particles may be directly blended when the styrene-based resin composition is extruded and kneaded, or, for ease of industrial production, a resin master batch containing inorganic fine particles at a known high concentration may be prepared in advance and then added.

[0137] <Preferred embodiment of the styrene-based resin composition according to the present embodiment> The styrene resin composition of the present embodiment has the resin (A) and the resin (B), and may contain, as necessary, one or more selected from the group consisting of a monohydric alcohol (C) having 10 or more carbon atoms, a core-shell type rubbery polymer particle (D), an impact resistant styrene resin (E), a styrene elastomer (F), a (meth)acrylonitrile-diene-styrene resin (G), an acrylic resin (H), and an optional additive component. The styrene resin composition of the present embodiment has a matrix polymer portion that essentially contains the resin (A) and the resin (B), and contains one or more optional components selected from the group consisting of a polymer matrix (E-1), a polymer matrix (G-1), a styrene elastomer (F), an acrylic resin (H), and an optional additive component.

[0138] In the matrix polymer portion of the styrene-based resin composition of the present embodiment, when the matrix polymer portion is divided into a high molecular weight component of 1 million or more and a molecular weight component of less than 1 million, the high molecular weight component of 1 million or more is preferably 5 mass% or less relative to the total amount of the styrene-based resin composition, more preferably 4 mass% or less, even more preferably 3 mass% or less, still more preferably 2 mass% or less, and most preferably 1 mass% or less. By controlling the content of the high molecular weight component having a molecular weight of 1 million or more to 5% by mass or less, the occurrence of unmelted defects is reduced, and a composition having an excellent balance between thin-wall moldability and strength can be obtained. The high molecular weight component having a molecular weight of 100 or more is the weight percentage of molecular weights of 1,000,000 or more calculated from the differential molecular weight distribution obtained by GPC, as will be described in the Examples section below.

[0139] The styrene-based resin composition of the present embodiment contains resin (A) and resin (B), and the total content of resin (A) and resin (B) is preferably 65 to 100 mass%, and more preferably 75 to 95 mass%, of the entire styrene-based resin composition.

[0140] The styrene-based resin composition of the present embodiment comprises resin (A), resin (B), and any additive components, and the total content of resin (A), resin (B), and any additive components is preferably 70 to 100 mass%, and more preferably 80 to 95 mass%, of the entire styrene-based resin composition.

[0141] The styrene-based resin composition of the present embodiment comprises resin (A), resin (B) and rubber-like polymer particles (D), and the total content of resin (A), resin (B) and rubber-like polymer particles (D) is preferably 70 to 100 mass%, and more preferably 80 to 90 mass%, of the entire styrene-based resin composition.

[0142] The styrene-based resin composition of the present embodiment comprises resin (A), resin (B), rubber-like polymer particles (D), and any additional components, and the total content of resin (A), resin (B), rubber-like polymer particles (D), and any additional components preferably accounts for 85 to 100 mass%, and more preferably 90 to 95 mass%, of the entire styrene-based resin composition.

[0143] The styrene-based resin composition of the present embodiment contains resin (A), resin (B), and resin (E), and the total content of resin (A), resin (B), and resin (E) is preferably 70 to 100 mass%, and more preferably 80 to 90 mass%, based on the entire styrene-based resin composition.

[0144] The styrene-based resin composition of the present embodiment comprises resin (A), resin (B), resin (E), and any additive components, and the total content of resin (A), resin (B), resin (E), and any additive components preferably accounts for 85 to 100 mass%, and more preferably 90 to 95 mass%, of the entire styrene-based resin composition.

[0145] The styrene-based resin composition of the present embodiment contains resin (A), resin (B), and elastomer (F), and the total content of resin (A), resin (B), and elastomer (F) is preferably 70 to 100 mass%, and more preferably 80 to 90 mass%, based on the entire styrene-based resin composition.

[0146] The styrene-based resin composition of the present embodiment comprises resin (A), resin (B), elastomer (F), and any additive components, and the total content of resin (A), resin (B), elastomer (F), and any additive components preferably accounts for 85 to 100 mass%, and more preferably 90 to 95 mass%, of the entire styrene-based resin composition.

[0147] The styrene-based resin composition of the present embodiment contains resin (A), resin (B), and resin (G), and the total content of resin (A), resin (B), and resin (G) is preferably 70 to 100 mass%, and more preferably 80 to 90 mass%, based on the entire styrene-based resin composition.

[0148] The styrene-based resin composition of the present embodiment comprises resin (A), resin (B), resin (G), and any additive components, and the total content of resin (A), resin (B), resin (G), and any additive components preferably accounts for 85 to 100 mass%, and more preferably 90 to 95 mass%, of the entire styrene-based resin composition.

[0149] The styrene-based resin composition of the present embodiment contains resin (A), resin (B), and resin (H), and the total content of resin (A), resin (B), and resin (H) is preferably 60 to 100 mass%, and more preferably 75 to 98 mass%, based on the entire styrene-based resin composition.

[0150] The styrene-based resin composition of the present embodiment comprises resin (A), resin (B), resin (H) and any additive components, and the total content of resin (A), resin (B), resin (H) and any additive components preferably accounts for 75 to 100 mass%, and more preferably 80 to 98 mass%, of the entire styrene-based resin composition.

[0151] The styrene-based resin composition of the present embodiment contains resin (A), resin (B), resin (G), and resin (H), and the total content of resin (A), resin (B), resin (G), and resin (H) is preferably 70 to 100 mass%, and more preferably 85 to 90 mass%, of the entire styrene-based resin composition.

[0152] The styrene-based resin composition of the present embodiment comprises resin (A), resin (B), resin (G), resin (H), and any additional components, and the total content of resin (A), resin (B), resin (G), resin (H), and any additional components preferably accounts for 85 to 100 mass%, and more preferably 90 to 95 mass%, of the entire styrene-based resin composition.

[0153] [Physical properties and characteristics of styrene-based resin compositions] The physical properties and characteristics of the styrene-based resin composition in this embodiment will be described below. <Vicat softening temperature> In this embodiment, the Vicat softening temperature of the styrene-based resin composition is preferably 105°C or higher, more preferably 109°C or higher, and even more preferably 110°C or higher. By setting the Vicat softening temperature at 105°C or higher, a sheet or container applicable to cooking in a general microwave oven of about 500W can be obtained, and by setting the Vicat softening temperature at 110°C or higher, it can withstand cooking in a high-power commercial microwave oven of 1000W or higher that is placed in a convenience store or the like. The Vicat softening temperature can be measured under conditions of a load of 50N (5kg load) and a temperature rise rate of 50°C / h in accordance with ISO306. When measuring the Vicat softening temperature, in the case of a hygroscopic resin, the Vicat softening temperature is measured after drying for 3 hours or more in a dryer with a ventilation function set at 80 to 90°C as necessary.

[0154] <Melt mass flow rate> In this embodiment, the melt flow rate of the styrene-based resin composition at 200° C. is preferably in the range of 0.1 to 2.0 g / 10 min, more preferably 0.2 to 1.5 g / 10 min, and even more preferably 0.4 to 1.0 g / 10 min. By making the melt flow rate 0.3 g / 10 min or more, good moldability can be obtained, and by making it 2.0 g / 10 min or less, a resin with excellent strength can be obtained.

[0155] <Content of conjugated diene monomer units> In this embodiment, the content of the conjugated diene monomer unit contained in the styrene-based resin composition is preferably 0% by mass or more, 0.1% by mass or more, 0.2% by mass or more, 0.3% by mass or more, 0.4% by mass or more, 0.5% by mass or more, 0.6% by mass or more, 0.7% by mass or more, 0.8% by mass or more, 0.9% by mass or more, 1.0% by mass or more, 1.1% by mass or more, 1.2% by mass or more, 1.3% by mass or more, 1.4% by mass or more, and 1.5% by mass or more, in that order, with respect to the entire styrene-based resin composition. The upper limit is preferably 10% by mass or less, 9% by mass or less, 8% by mass or less, 7% by mass or less, 6% by mass or less, 5% by mass or less, 4% by mass or less, 3.8% by mass or less, 3.6% by mass or less, 3.4% by mass or less, 3.2% by mass or less, 3.0% by mass or less, 2.8% by mass or less, 2.6% by mass or less, and 2.5% by mass or less, in that order. The range of the content of the conjugated diene monomer unit can be any combination of the above lower limit and upper limit. In particular, by setting the content of the conjugated diene monomer unit in the range of 0.6 to 4.0 mass%, it is possible to obtain a composition having an excellent balance between low-temperature impact strength and rigidity, and a molded body, sheet, or container obtained by molding the composition.

[0156] As described above, the conjugated diene monomer unit is a general term for the conjugated diene monomer (d2), the conjugated diene monomer (e1), the conjugated diene monomer (f2) and the conjugated diene monomer (g2).

[0157] <(Meth)acrylic acid monomer unit or (meth)acrylic acid ester monomer unit in styrene-based resin composition> In this embodiment, the content of all (meth)acrylic acid monomer units contained in the styrene-based resin composition is preferably 2 to 20 mass% relative to the total amount (100 mass%) of the styrene-based resin composition, preferably 3 to 15 mass%, more preferably 4 to 10 mass%, and even more preferably 5 to 8 mass%. When the content of (meth)acrylic acid monomers in the entire composition is within the above range, a sufficient effect of improving heat resistance can be obtained.

[0158] The total (meth)acrylic acid monomer content indicates the total amount of all (meth)acrylic acid monomer units present in the styrene-based resin composition, and therefore includes the respective contents of (meth)acrylic acid monomer units in the resin (A), the resin (B) and other components (rubber-like polymer particles (D), the resin (E), the elastomer (F), the resin (G), the resin (H) and any added components).

[0159] In this embodiment, the content of all (meth)acrylic acid ester monomer units contained in the styrene-based resin composition is preferably 6 to 55 mass% relative to the total amount (100 mass%) of the styrene-based resin composition, preferably 10 to 50 mass%, more preferably 14 to 45 mass%, and even more preferably 16 to 40 mass%. When the content of the (meth)acrylic acid ester monomers in the entire composition is within the above range, the effect of improving the mechanical strength can be sufficiently obtained.

[0160] The above-mentioned total (meth)acrylic acid ester monomer content indicates the total amount of all (meth)acrylic acid ester monomer units present in the styrene-based resin composition, and therefore includes the respective contents of (meth)acrylic acid ester monomer units in the resin (A), the resin (B) and other components (rubber-like polymer particles (D), the resin (E), the elastomer (F), the resin (G), the resin (H) and any added components).

[0161] By controlling the contents of all (meth)acrylic acid monomer units and all (meth)acrylic acid ester monomer units contained in the styrene-based resin composition within the above ranges, the heat resistance improving effect due to the (meth)acrylic acid monomer units and the strength improving effect due to the (meth)acrylic acid ester monomer units can be efficiently obtained simultaneously.

[0162] <Styrene-based monomer units in styrene-based resin composition> In this embodiment, the (all) styrene-based monomer units refer collectively to the styrene monomer units contained in the resin (A), the resin (B) and other components (the rubber-like polymer particles (D), the resin (E), the elastomer (F), the resin (G), the resin (H) and any added components).

[0163] In the present embodiment, the (total) styrene monomer unit content is preferably 35 to 85 mass%, more preferably 40 to 80 mass%, and further preferably 45 to 75 mass%, relative to the total amount (100 mass%) of the styrene resin composition. When the content is in the range of 35 to 85, a styrene resin composition having an excellent balance between moldability and heat resistance can be obtained.

[0164] In a preferred embodiment of the styrene-based resin composition in this embodiment, the content of the styrene-based monomer unit is 35 to 85 mass%, the content of the (meth)acrylic acid monomer unit is 2 to 20 mass%, and the content of the (meth)acrylic acid ester monomer unit is 6 to 55 mass%, relative to the total amount (100 mass%) of the styrene-based resin composition. In another preferred embodiment, the content of the styrene-based monomer unit is 45 to 75 mass%, the content of the (meth)acrylic acid monomer unit is 4 to 10 mass%, the content of the (meth)acrylic acid ester monomer unit is 16 to 40 mass%, and the content of the conjugated diene monomer unit is 0.5 to 10 mass%, relative to the total amount (100 mass%) of the styrene-based resin composition.

[0165] <Styrene monomer residue> In a preferred aspect of the styrene-based resin composition in this embodiment, the residue of styrene-based monomer units generated during the production of each resin, relative to the total amount (100 mass%) of the styrene-based resin composition, is preferably 0.3 mass% or less, more preferably 0.2 mass% or less, 0.1 mass% or less, 0.08 mass% or less, 0.07 mass% or less, and 0.06 mass% or less, in that order.

[0166] <Styrene oligomer content> In a preferred aspect of the styrene-based resin composition in this embodiment, the content of styrene dimers and trimers generated during the production of each resin, relative to the total amount (100 mass%) of the styrene-based resin composition, is preferably 1.0 mass% or less, and more preferably 0.9 mass% or less, 0.8 mass% or less, 0.7 mass% or less, 0.6 mass% or less, 0.5 mass% or less, 0.4 mass% or less, and 0.3 mass% or less, in that order.

[0167] The average particle size of all rubber-like polymer particles contained in the styrene-based resin composition of this embodiment is preferably 0.08 to 5.0 μm, more preferably 0.10 to 4.0 μm, even more preferably 0.20 to 2.5 μm, and even more preferably 0.25 to 2.0 μm. When the average particle size of all the rubber-like polymer particles, that is, the apparent rubber-like polymer particles, is within the above range, the effect of imparting strength to the styrene-based resin composition is maximized.

[0168] The total amount of all rubber-like polymer particles (including encapsulated resin) in the entire styrene-based resin composition of this embodiment is preferably 0.5 to 25 mass%, more preferably 0.6 to 15 mass%, even more preferably 0.7 to 10 mass%, and even more preferably 0.8 to 5.5 mass%, relative to the total amount (100 mass%) of the styrene-based resin composition. When the content of all the rubber-like polymer particles contained in the styrene-based resin composition is within the above range, the effect of imparting strength to the styrene-based resin composition is maximized.

[0169] In addition, when each of the rubbery polymer particles, i.e., the ABS rubbery polymer particles (G-2), the core-shell type rubbery polymer particles (D) and the rubbery polymer particles (E-2), encapsulates components other than conjugated diene monomer units as grafts or occluded units, the content of all rubbery polymer particles includes the components other than the conjugated diene monomer units.

[0170] [Injection molded product] Another embodiment of the present disclosure is an injection molded article formed using the above-mentioned styrene-based resin composition of the present invention. The injection molded article is of any shape molded, for example, by an injection molding machine composed of a general hopper, cylinder, and mold, at a cylinder temperature of 150 to 290°C and a mold temperature of 40 to 80°C. The cylinder temperature is preferably in the range of 170 to 280°C, more preferably 190 to 270°C, and even more preferably 200 to 260°C, and the mold temperature is preferably in the range of 45°C to 75°C, more preferably 50 to 70°C, and even more preferably 55 to 65°C.

[0171] [Extruded sheet] Another aspect of the present disclosure provides an extruded sheet formed using the above-mentioned styrene-based resin composition of the present invention. The extruded sheet may be either non-foamed or foamed. A commonly known method can be used as a method for producing an extruded sheet. A method for producing a non-foamed extruded sheet can be a method using a single-axis or twin-axis extruder equipped with a T-die and a device for taking up a sheet with a single-axis or twin-axis stretching machine, and a method for producing a foamed extruded sheet can be a method using an extrusion foaming machine equipped with a T-die or circular die.

[0172] <Foam extrusion sheet> The foamed extruded sheet of the present invention can be obtained by a conventionally known method, so-called extrusion foaming, in which the base resin and various additives, such as a foaming nucleating agent (cell regulator) described below, which are added as required, are heated, melted, and kneaded using an extruder, a physical foaming agent is injected and further kneaded, and the foamable molten resin, which has been adjusted to an appropriate resin temperature, is extruded through a die under atmospheric pressure to foam the sheet.

[0173] In this embodiment, when forming a foamed extrusion sheet, a substance that is usually used can be used as a foaming agent during extrusion foaming. As the foaming agent, normal butane, isobutane, pentane, chlorofluorocarbon, carbon dioxide, water, diethyl ether, etc. can be used, and butane, isobutane, and diethyl ether are preferable, and two or more of the above foaming agents can be used in combination. The amount of foaming agent added during foam molding is preferably 0.5 to 8.0 parts by mass, more preferably 1.0 to 6.0 parts by mass, even more preferably 2.0 to 5.0 parts by mass, and even more preferably 2.5 to 4.5 parts by mass, when the styrene-based resin composition to be foamed is 100 parts by mass. In particular, by setting the amount in the range of 2.0 to 5.0 parts by mass, the resin plasticization effect and foamability are excellent.

[0174] In this embodiment, when forming a foamed extruded sheet, a substance that is usually used as a foam nucleating agent during extrusion foaming can be used. For example, talc, silica, mica, etc., which are listed as the inorganic particles, can be used. The content of the foam nucleating agent is preferably 0.1 to 7.0 parts by mass, more preferably 0.2 to 6.0 parts by mass, and even more preferably 0.3 to 4.0 parts by mass, when the total amount of the styrene-based resin composition is 100 parts by mass. By setting the content in the range of 0.1 to 7.0 parts by mass, a sheet with an expansion ratio suitable for a foamed sheet for food packaging can be obtained. The foam nucleating agent may be added directly, or a master batch may be used in which a resin pellet in which a high concentration of the foam nucleating agent is dispersed by extrusion kneading in advance is added.

[0175] In this embodiment, the thickness of the foamed extruded sheet is preferably 0.3 mm to 5.0 mm, more preferably 0.5 to 3.0 mm. By setting the thickness in the range of 0.5 to 3.0 mm, it is possible to provide a foamed extruded sheet having an excellent balance between strength and productivity.

[0176] In this embodiment, the apparent density of the foamed extruded sheet is 0.05 to 0.30 g / cm 3 and more preferably, 0.06 to 0.20 g / cm 3 , more preferably 0.07 to 0.10 g / cm3 In particular, 0.07 to 0.10 g / cm 3 By setting the range, it is possible to provide a foamed extruded sheet having an excellent balance between strength and productivity.

[0177] In this embodiment, the basis weight of the foamed extruded sheet is 70 to 300 g / m 2 and more preferably 75 to 250 g / m 2 , and more preferably 80 to 200 g / m 2 , and even more preferably 90 to 150 g / m 2 Especially 80~200g / m 2 By setting the range, it is possible to provide a foamed extruded sheet having an excellent balance between strength and productivity.

[0178] In this embodiment, the expansion ratio of the foamed extruded sheet is preferably 5 to 18 times, more preferably 6 to 17 times, even more preferably 7 to 16 times, and even more preferably 8 to 15 times.

[0179] In the present embodiment, the closed cell ratio of the foamed extruded sheet determined in accordance with the method of JIS K7138: 2006 is preferably 75% or more, more preferably 80% or more, even more preferably 83% or more, and even more preferably 86% or more. In particular, by making the closed cell ratio 80% or more, fragile open cells are reduced, so that a foamed sheet having excellent strength can be obtained.

[0180] In this embodiment, the average bubble diameter of the foamed extruded sheet is preferably 200 to 500 μm, more preferably 250 to 450 μm. By setting the range to 200 to 500 μm, it is possible to provide a foamed extruded sheet having an excellent balance between strength and productivity.

[0181] The foamed extruded sheet of the present invention may be multi-layered by further laminating a film. The type of film used may be any type commonly used for polystyrene. For example, a PP (polypropylene) / PS (polystyrene) dry laminate film may be used, and the thickness of the film to be laminated is preferably 5 to 200 μm, more preferably 10 to 150 μm, and even more preferably 20 to 100 μm. By setting the thickness in the range of 20 to 100 μm, a good balance of weight reduction, strength, and oil resistance reinforcement is achieved.

[0182] A preferred foam extrusion sheet of this embodiment is a laminate having a foam layer of a styrene-based resin composition, a polystyrene layer provided on at least one side of the foam layer, and a polypropylene layer provided on the cotton of the polystyrene layer. With this structure, a polypropylene layer is provided on the outermost layer that may come into contact with food, etc., so that a container with excellent oil resistance can be provided. In addition, since the foam layer of the styrene-based resin composition contains a styrene-based monomer unit, a container with excellent compatibility and adhesion with the polystyrene layer can be provided.

[0183] The secondary molded product obtained by thermoforming the foamed sheet is suitable for use as a container for food heated in a microwave oven. Examples of the thermoforming method include vacuum molding and compressed air molding. Such a thermoforming method is a preferred method since it can obtain containers continuously in a short time. When the laminated sheet having the above-mentioned laminate film thermocompression-bonded thereto is thermoformed, it is preferable to mold the laminate so that the polyolefin resin film having excellent oil resistance is located on the inside of the molded product obtained.

[0184] <Non-foamed extruded sheet> In this embodiment, the thickness of the non-foamed extruded sheet is preferably 0.1 mm to 3.0 mm, more preferably 0.12 to 2.0 mm, even more preferably 0.15 to 1.0 mm, and even more preferably 0.2 to 0.7 mm. By setting the thickness in the range of 0.1 to 3.0 mm, it is possible to provide a non-foamed extruded sheet having an excellent balance between strength and productivity.

[0185] <Biaxially oriented sheet> The non-foamed extruded sheet may be a biaxially stretched sheet which is formed into a sheet and is biaxially stretched to impart strength. A commonly known method may be used as a method for producing a biaxially stretched sheet. The biaxially stretched sheet is produced by stretching the sheet in the machine direction (MD) with a roll and then stretching the sheet in the perpendicular direction (TD) with a tenter. Alternatively, the biaxially stretched sheet may be produced by sequentially or simultaneously biaxially stretching the styrene resin composition formed into a plate shape in a state of being heated to about +10 to 40°C above the Vicat softening temperature of the composition with a tenter. The biaxially stretched sheet may be multilayered with a styrene resin other than the styrene resin composition, such as a polystyrene resin. The biaxially stretched sheet may be multilayered with a resin other than the styrene resin. Examples of the resin other than the styrene resin include PET resin and nylon resin.

[0186] In this embodiment, the stretching ratio of the biaxially oriented sheet is preferably about 1.3 to 7.0 times in the MD direction and about 1.3 to 7.0 times in the TD direction in terms of strength.

[0187] In this embodiment, the orientation relaxation stress in the machine direction and the cross direction of the biaxially oriented sheet is preferably in the range of 0.4 to 1.3 MPa. By adjusting the orientation relaxation stress within this range, the strength of the molded product of the biaxially oriented sheet can be maintained.

[0188] In a preferred embodiment of the present invention, a known anti-fogging agent may be applied to one side of the biaxially oriented sheet in order to prevent fogging caused by moisture volatilizing from food when the sheet is used as a food packaging container. Examples of the anti-fogging agent include nonionic surfactants such as sucrose fatty acid esters and polyglycerin fatty acid esters, polyether-modified silicone oils, etc.

[0189] The method for coating the biaxially stretched sheet with the antifogging agent is not particularly limited, and examples of the method include coating using a roll coater, a knife coater, a gravure roll coater, etc. Spraying, immersion, etc. may also be used. Before coating, the sheet surface may be treated with a corona treatment, an ozone treatment, a primer treatment, etc. to improve the wettability of the sheet surface before coating.

[0190] Another aspect of the present invention provides a molded product formed using the biaxially oriented sheet described above. The biaxially oriented sheet or a multilayer body containing the same can be molded, for example, by vacuum forming to produce a lid for a lunch box or a container for storing side dishes. In particular, a transparent lid for a food packaging container suitable for microwave cooking is preferred because the features of the present invention can be fully utilized. EXAMPLES

[0191] The present invention will now be described in detail with reference to examples and comparative examples, but the present invention is not limited to these examples. The resins, injection molded articles, extruded sheets, etc. in the examples and comparative examples were analyzed and evaluated as follows.

[0192] [Evaluation of properties of each resin and resin composition] (1-1) Measurement of molecular weight and the ratio of molecular weight components of 1 million or more The average molecular weights (Mn, Mw, Mz) and the ratios of high molecular weight components of 1 million or more of each of the resins and resin compositions produced in the examples and comparative examples were measured as standard polystyrene-equivalent molecular weights by gel permeation chromatography (GPC) under the following conditions using a calibration curve method using standard polystyrene. Measuring equipment: Tosoh HLC-8220 Separation column: Two Tosoh TSK gel Super HZM-H (inner diameter 4.6 mm) connected in series Guard column: Tosoh TSK guard column Super HZ-H Measurement solvent: tetrahydrofuran (THF) Sample concentration: 10 mg of the measurement sample was dissolved in 10 mL of a solvent and filtered through a 0.45 μm filter. Injection volume: 10μL Measurement temperature: 40℃ Flow rate: 0.35mL / min Detector: Differential refractometer To create the calibration curve, 11 types of TSK standard polystyrene (F-850, F-450, F-128, F-80, F-40, F-20, F-10, F-4, F-2, F-1, A-5000) manufactured by Tosoh were used. The calibration curve was created using a linear approximation equation. If there was any THF insoluble matter in the composition, the THF insoluble matter was removed using a membrane filter of about 0.2 to 0.4 μm before measurement.

[0193] (1-2) Measurement of the content of monohydric alcohols having 10 or more carbon atoms in styrene-based resin compositions The content of monohydric alcohol having 10 or more carbon atoms in the entire styrene-based resin composition produced in the examples and comparative examples was measured by gas chromatography under the following conditions. Sample preparation: 1.0 g of resin was dissolved in 5 mL of methyl ethyl ketone, and then 5 mL of hexane containing 200 μg / g of p-diethylbenzene as a standard substance was added to reprecipitate the polymer component, and the supernatant was collected and used as the measurement solution. Measurement equipment: Agilent 8860 series GC system Column: Frontier Labs Ultra ALLOY-CW UACW-30M-0.25F (WAX column) Length: 30m Film thickness: 0.25μm Diameter: 0.25mmφ Injection volume: 1μL Split ratio: 5:1 Column temperature: 100°C for 5 minutes → 10°C / min to 180°C → 20°C / min to 220°C → 20 minutes at 220°C Inlet temperature: 230℃ Detector temperature: 300℃ Carrier gas: Helium Helium flow rate: 2.6mL / min Detector: FID FID hydrogen flow rate: 40mL / min Air flow rate: 450mL / min Make-up flow rate: 50mL / min In addition, when detecting the peak of the monohydric alcohol (C) having 10 or more carbon atoms, in order to avoid overlapping with other peaks or saturation of the peak intensity, pretreatment such as the dilution rate of the sample, the column to be used, and the detection conditions may be appropriately adjusted.

[0194] (1-3) Measurement of each monomer unit content The content of each monomer unit contained in the resin compositions prepared in the Examples and Comparative Examples was measured by pyrolysis GC / MS under the following conditions. Sample preparation: 50 μg to 100 μg of the resin compositions prepared in the examples and comparative examples were weighed out using a precision balance into a sample cup, and measurements were performed under the following conditions. Measurement conditions Pyrolysis Unit Equipment: Frontier Labs PY-3030D Furnace temperature: 600℃ GC Equipment: Shimadzu GCMS-GP2020NX Column: Ultra Alloy-5 (Length 30m, film thickness 0.25μm, diameter 0.250mmφ) Column temperature: held at 50°C for 5 minutes, then heated at 10°C / min. From 100°C, the temperature was increased at 7°C / min and held at 300°C for 10 minutes. Inlet temperature: 300℃ Detector temperature: 300℃ Split ratio: 1 / 300 Carrier gas: Helium Detection method: Mass spectrometer (MSD) In detecting each monomer peak, the amount of sample, the column to be used, and the detection conditions may be appropriately adjusted to avoid peak overlap and saturation of peak intensity.

[0195] (1-4) Measurement of the average particle size of the core-shell type rubbery polymer particles (D), the rubbery polymer particles (E-2) in the resin (E), and the rubbery polymer particles (G-2) in the resin (G) The average particle size (μm) of the core-shell type rubbery polymer particles (D), the rubbery polymer particles (E-2) in the resin (E), and the rubbery polymer particles (G-2) in the resin (G) was determined by observing the cross sections of 200 rubbery polymer particles using a transmission electron microscope, using the following formula (2): Average particle diameter=Σ(ni×Di 4 ) / Σ(ni×Di 3 ) {In the above formula (2), ni is the number of rubber-like polymer particles having a particle diameter Di, and Di is the average value of the major axis and minor axis of the rubber-like polymer particles.} The particle diameters were calculated by averaging the particle diameters obtained from images of five fields of view.

[0196] (1-5) Measurement of Melt Mass Flow Rate (MFR) The melt mass flow rate (g / 10 min) of each of the resins and resin compositions produced in the Examples and Comparative Examples was measured in accordance with ISO1133 under conditions of 200° C. and 50 N (5 kg load).

[0197] (1-6) Measurement of Vicat softening temperature The Vicat softening temperature of each resin and resin composition produced in the examples and comparative examples was measured in accordance with ISO 306. The load was 50 N (5 kg load), and the heating rate was 50°C / h. Those with a Vicat softening temperature of over 105°C had excellent dimensional stability at temperatures assumed when heating sheet molded products and container molded products in a microwave oven, and those with a Vicat softening temperature of over 110°C in particular tended to show almost no dimensional change at practical temperatures.

[0198] (1-7) Impact strength of solid sheet (press molded) (23℃) Each resin composition produced in the examples and comparative examples was dried at 80°C for 2 hours or more, and then a solid sheet of 0.7 mm thickness was made using a compression molding machine. After cutting into 8 x 8 cm pieces, the pieces were left to stand in a thermostatic chamber maintained at 23°C and conditioned overnight. After that, the film impact was measured using a film impact tester (No. 195) manufactured by Toyo Seiki Co., Ltd., and the n8 average value was recorded.

[0199] (1-8) Low-temperature impact strength (-20℃) of solid sheet (press molded) Each resin composition produced in the examples and comparative examples was dried at 80°C for 2 hours or more, and then a solid sheet of 0.7 mm thickness was made using a compression molding machine. It was cut into 6 cm x 6 cm pieces and cooled in a thermostatic chamber set at -30°C for 2 hours or more, and then the drop weight impact strength was immediately measured using a DuPont impact tester (No. 451) manufactured by Toyo Seiki Co., Ltd. The mass of the falling weight was 0.10 kg, the radius of the tip of the impact center was 6.3 mm, and the radius of the impact center receiving stand was 9.4 mm. The drop weight impact strength was calculated as the 50% destruction value, calculated by (mass of the falling weight 0.10 kg) x (height cm).

[0200] (1-9) Tensile test and bending test (1-9-1) Preparation of injection molded body Each of the pellet-shaped resin compositions produced in the Examples and Comparative Examples was molded into a 4 mm dumbbell of Type A using an EC60N manufactured by Toshiba Machine Co., Ltd. under the following conditions. Pellet drying: 80℃ for 2 hours or more Measurement: 63mm Injection time: 20 seconds Pressure retention time: 10 seconds Pressure switching: 8~11mm Holding pressure: 1.1 times the maximum injection pressure Back pressure: 15MPa Cylinder temperature: 220-240-220-200℃ from nozzle side to hopper side Screw rotation speed: 100 rpm Cushion: 5.0~5.5mm Mold temperature: 45℃ Cooling time: 25 seconds The obtained injection molded articles were subjected to the following evaluations.

[0201] (1-9-2) Dumbbell tensile test (dumbbell tensile breaking point, dumbbell SS curve area) A dumbbell tensile test was carried out on the 4 mm thick dumbbell obtained in the previous section (1-9-1) in accordance with JIS K7161 (tensile speed 5 mm / min) to measure the dumbbell tensile breaking point. The dumbbell SS curve area (N·mm) was also calculated from the obtained SS curve. The above measurements were carried out in a thermostatic chamber maintained at 23°C and in a thermostatic bath maintained at -20°C.

[0202] (1-9-3) Bending test (flexural modulus, maximum bending point) A test piece of 80 x 10 x 4 mm was cut from the dumbbell piece obtained in the previous section (1-9-1) using a cutting machine. A bending test was carried out at a bending speed of 2 mm / min in accordance with JIS K7171, and the bending modulus and maximum bending point were measured. The above measurements were carried out in a temperature-controlled room maintained at 23°C.

[0203] [Characteristics evaluation of non-foamed extruded sheets] (2-1) Heat resistance evaluation of non-foamed extruded sheets The non-foamed continuous extruded sheets and biaxially oriented sheets produced in the Examples and Comparative Examples were cut into strips of 10 cm x 1.5 cm with the MD direction as the long side, and placed in an oven set at 110°C for 60 minutes, after which the deformation of the foamed extruded sheets was measured, and the heat resistance was evaluated as follows based on the thermal deformation. Specifically, the above dimensional change was measured using the following formula (I) to measure the amount of change in a 10 cm length before and after thermal deformation, and the n5 average was used as the value. Formula (I): Dimensional change (%) = (MD length of non-foamed sheet after being placed in an oven for 60 minutes - MD length of non-foamed sheet before being placed in an oven) / MD length of non-foamed sheet before being placed in an oven A: Dimensional change 0.5% or less B: Dimensional change: over 0.5% to 2% C: Dimensional deformation over 2%

[0204] (2-2) Surface impact of non-foamed extruded sheet The non-foamed continuous extrusion sheets and biaxially stretched sheets produced in the Examples and Comparative Examples were cut into 8 x 8 cm pieces, and the film impact was measured using a film impact tester (No. 195) manufactured by Toyo Seiki Seisakusho Co., Ltd., and the n8 average value was taken as the value. The above measurements were carried out in a thermostatic chamber maintained at 23°C.

[0205] (2-3) Low-temperature impact strength of non-foamed extruded sheet (-20℃) The non-foamed continuous extrusion sheets and biaxially oriented sheets produced in the Examples and Comparative Examples were cut into 6 cm x 6 cm pieces and cooled in a thermostatic chamber set at -30°C for at least 2 hours, after which the drop weight impact strength was immediately measured using a DuPont impact tester (No. 451) manufactured by Toyo Seiki Co., Ltd. The mass of the falling weight was 0.10 kg, the radius of the tip of the impact center was 6.3 mm, and the radius of the impact center receiving stand was 9.4 mm, and the drop weight impact strength was calculated as the 50% fracture value, calculated as (mass of the falling weight 0.10 kg) x (height cm).

[0206] [Evaluation of properties of foam extrusion sheets] (3-1) Heat resistance evaluation of foam extrusion sheets The foamed extruded sheets produced in the Examples and Comparative Examples were cut into strips of 10 cm x 1.5 cm with the MD direction as the long side, and placed in an oven set at 110°C for 60 minutes. The deformation of the foamed extruded sheets was then measured, and the heat resistance was evaluated based on the thermal deformation as follows. Specifically, the above dimensional change was measured by measuring the amount of change in a 10 cm length before and after thermal deformation according to the following formula (II), and the n5 average was used as the value. Formula (II): Dimensional change (%) = (MD length of foamed sheet after being placed in oven for 60 minutes - MD length of foamed extruded sheet before being placed in oven) / MD length of foamed extruded sheet before being placed in oven A: Dimensional change of 1% or less B: Dimensional change: over 1% to 3% C: Dimensional deformation over 3%

[0207] (3-2) Surface impact of foam extrusion sheet The foamed extruded sheets produced in the Examples and Comparative Examples were cut into 8 x 8 cm pieces, and the film impact (kg cm) was measured using a Toyo Seiki Film Impact Tester (No. 195), and the n8 average was used as the value and evaluated according to the following criteria. The measurements were carried out in a thermostatic room maintained at 23°C. A+: More than 10 kg cm A: 7kg cm or more, less than 10kg cm B: 5kg cm or more, less than 8kg cm C: Less than 5kg cm

[0208] (3-3) Low-temperature impact strength of foam extrusion sheet (-20℃) The foamed extruded sheets produced in the Examples and Comparative Examples were cut into 6 cm x 6 cm pieces and cooled in a thermostatic chamber set at -30°C for at least 2 hours, after which the drop weight impact strength was immediately measured using a DuPont impact tester (No. 451) manufactured by Toyo Seiki Co., Ltd. The mass of the falling weight was 0.10 kg, the radius of the tip of the impact center was 6.3 mm, and the radius of the impact center receiving stand was 9.4 mm. The drop weight impact strength was calculated as the 50% destruction value, calculated as (mass of the falling weight 0.10 kg) x (height cm), and evaluated according to the following criteria. A+: More than 5 kg cm A: 3kg cm or more, less than 5kg cm B: 1kg·cm or more, less than 3kg·cm C: Less than 1kg cm

[0209] (3-4) Preparation and evaluation of laminated foam sheet by laminating polyolefin resin film and foam extrusion sheet A CPP / PS laminate film (45 μm thick) made by dry laminating CPP 25 μm (Suntox KT) and CPS 20 μm (Oishi Sangyo SPH) and an extruded sheet produced in the examples and comparative examples were passed between a heated roll and a backup roll at 195°C to pressure-laminated the film onto a foam sheet to obtain a laminated foam sheet. At this time, the line speed was set to 16 m / min, and the gap between the heated roll and the backup roll was set to 0.5 mm. The low-temperature strength of the laminated foam sheet was evaluated according to the procedure in the previous section (3-3).

[0210] [Evaluation of the properties of molded products obtained by secondary molding of extruded sheets] The biaxially oriented sheets produced in the Examples and Comparative Examples were molded into a lid-shaped body measuring 160 mm long, 140 mm wide, and 40 mm high using a hot plate molding machine at a hot plate temperature of 145° C. and a heating time of 2.0 seconds. In addition, the foamed extruded sheets produced in the examples and comparative examples were molded into foamed containers with a diameter of 200 mm and a height of 45 mm, into which an inner fitting lid could be fitted, using a hot plate molding machine under conditions of a hot plate temperature of 285°C and a heating time of 5.0 seconds. The above two types of secondary molded bodies were subjected to the following evaluations (heat resistance, surface impact, and low-temperature impact).

[0211] (4-1) Heat resistance evaluation of secondary molded bodies (containers and lids) The secondary molded body produced in the previous section was placed in an oven set at 110°C for 60 minutes, after which the deformation of the secondary molded body was measured and the heat resistance was evaluated based on the amount of thermal deformation as follows. Specifically, the dimensional change was evaluated from the amount of thermal deformation in the length of the longest piece. Equation (II): Dimensional change (%) = (length of the longest piece of the secondary molded body after being placed in the oven for 60 minutes - length of the longest piece of the secondary molded body before being placed in the oven) / length of the longest piece of the secondary molded body before being placed in the oven A: Dimensional change of 1% or less B: Dimensional change: over 1% to 3% C: Dimensional deformation over 3%

[0212] (4-2) Surface impact of secondary molded bodies (containers and lids) The secondary molded product produced in the previous section was cut into 8 x 8 cm pieces, and the film impact (kg cm) was measured using a Toyo Seiki film impact tester (No. 195), and the n8 average was used as the value and evaluated according to the following criteria. The above measurements were carried out in a thermostatic room maintained at 23°C. A+: More than 10 kg cm A: 7kg cm or more, less than 10kg cm B: 5kg·cm or more, less than 8kg·cm C: Less than 5kg cm

[0213] (4-3) Low-temperature impact strength (-20°C) of secondary molded bodies (containers and lids) The secondary molded body produced in the previous section was cut into 6 cm x 6 cm pieces and cooled in a thermostatic chamber set at -30°C for at least 2 hours, after which the drop weight impact strength was immediately measured using a DuPont impact tester (No. 451) manufactured by Toyo Seiki Co., Ltd. The mass of the falling weight was 0.10 kg, the radius of the tip of the impact point was 6.3 mm, and the radius of the impact point support was 9.4 mm. The drop weight impact strength was calculated as the 50% destruction value, calculated by (mass of the falling weight 0.10 kg) x (height in cm), and evaluated according to the following criteria. A+: More than 5 kg cm A: 3kg cm or more, less than 5kg cm B: 1kg·cm or more, less than 3kg·cm C: Less than 1kg cm

[0214] [Preparation of each resin and production examples of styrene-based resin composition] The preparation of each resin and a specific method for producing the styrene-based resin composition will be described below. <Production Example of Styrene-Unsaturated Carboxylic Acid Resin (A)> -Preparation of resin (A1)- A polymerization raw material composition liquid consisting of 65.5 parts by mass of styrene, 3.3 parts by mass of methyl methacrylate, 5.8 parts by mass of methacrylic acid, 22.9 parts by mass of ethylbenzene, 2.5 parts by mass of 2-ethyl-1-hexanol, and 0.027 parts by mass of 1,1-bis(t-butylperoxy)cyclohexane was supplied to a complete mixing type reactor having a capacity of 3.6 liters at a rate of 0.8 liters / hour, and then continuously supplied to a volatilization device connected to a single screw extruder that removes volatile components such as unreacted monomers and polymerization solvents. The polymerization temperature of the complete mixing reactor was set to 130°C. The temperature of the single screw extruder was set to 210 to 240°C, and the pressure was set to 10 torr, and volatile components such as unreacted monomers and polymerization solvents were volatilized. The volatilized volatile components were condensed in a condenser through which a refrigerant of -5°C was passed, and were recovered as unreacted liquid, and the styrene-based resin was recovered as resin pellets. The physical properties of the resin (A1) obtained by the above-mentioned analytical methods are shown in Table 1 below.

[0215] -Preparation of resin (A2)- Resin (A2) was prepared in the same manner as for the above resin (A1) except that methyl methacrylate was not used as a copolymerizable comonomer and the polymerization conditions were adjusted. The composition and physical properties of the obtained resin (A2) are shown in Table 1.

[0216] -Preparation of resin (A3)- Resin (A3) was prepared in the same manner as for resin (A2) above, except that n-octanol was used instead of 2-ethyl-1-hexanol used as the polymerization solvent in the previous section, and the polymerization conditions were adjusted. The composition and physical properties of the obtained resin (A3) are shown in Table 1.

[0217] -Preparation of resin (A4)- Using only styrene as a monomer, a styrene homopolymer resin (A4) having the composition and physical properties shown in Table 1 was obtained in the same manner as above.

[0218] [Table 1]

[0219] <(Meth)acrylic resin (B) used in the examples> In the examples of this specification, resins B1 to B9 having the compositions and properties shown in Table 2 below were used as the (meth)acrylic resin (B).

[0220] [Table 2]

[0221] <Monohydric alcohol (C) having 10 or more carbon atoms used in the examples> In the examples of this specification, the following alcohol species were used as the monohydric alcohol (C) having 10 or more carbon atoms. (C1) Nissan Chemical Fine Oxocol 180, compound name: (5,7,7-trimethyl-2-(1,3,3-trimethylbutyl)-1-octanol (C2) Kao Corporation Kalcol 8089 Compound name: Stearyl alcohol (C3) Kao Corporation Emulgen 109P Compound name: Polyoxyethylene (9) lauryl ether monoalcohol

[0222] <Production Example of Core-Shell Type Rubber Polymer Particles (D)> -Preparation of rubber-like polymer particles (D1)- In a pressure vessel equipped with a stirrer, 200 parts by mass of pure water, 0.002 parts by mass of disodium salt of ethylenediaminetetraacetic acid, 0.0012 parts by mass of ferrous sulfate, 0.008 parts by mass of disodium salt of ethylenediaminetetraacetic acid, and 0.03 parts by mass of sodium polyoxyethylene alkyl ether phosphate were charged, and after deacidification, 100 parts by mass of butadiene, 0.05 parts by mass of sodium formaldehyde sulfoxylate, and 0.2 parts by mass of paramenthane hydroperoxide were added, and then 1.4 parts by mass of sodium polyoxyethylene alkyl ether phosphate was added dropwise over 6 hours. The reaction solution was kept at pH 6.5 to 7.5 at 50°C for 124 hours, and a diene rubber latex with a conversion rate of 98% by weight and an average particle size of 0.18 μm was obtained.

[0223] Next, while maintaining the rubber latex obtained above (solid content about 71 parts) at 60 ° C, 55 parts by mass of methyl methacrylate and 5 parts by mass of n-butyl acrylate as monomers were added over 1 hour. Simultaneously with the addition of the above monomers, 0.09 parts by mass of t-butyl hydroperoxide and 0.1 parts by mass of sodium formaldehyde sulfoxylate were started to be added, and then the entire amount was added over 2 hours while maintaining the pH of the reaction solution at 6.5 to 7.5 and the temperature at about 60 ° C. The reaction solution was further maintained at about 60 ° C for 1 hour to prepare a graft copolymer latex with an average particle size of 200 nm, and after adding 1 part by mass of Irganox 1076 as an antioxidant, the mixture was coagulated with an aqueous calcium chloride solution, washed with water, dehydrated and dried to obtain rubber-like polymer particles (D1) as powder. The composition and physical properties of the rubber-like polymer particles (D1) are shown in Table 3. -Preparation of rubber-like polymer particles (D2)- The feed amount of each monomer and the polymerization conditions were adjusted, and D2 was prepared in the same manner as D1 above. The composition and physical properties of the obtained rubber-like polymer particles (D2) are shown in Table 3.

[0224] [Table 3] As the rubber-like polymer particles (D3), Metablen C223A manufactured by Mitsubishi Chemical Corporation was used.

[0225] <Production example of impact resistant styrene resin (E)> -Preparation of impact-resistant styrene-based resin (E1)- An impact-resistant styrene resin (E1) (hereinafter referred to as resin (E1)) was produced using a polymerization apparatus in which three laminar flow reactors (1.5 liters) equipped with stirrers were connected in series and followed by a two-stage vented extruder. 82.4 parts by mass of styrene, 9.0 parts by mass of ethylbenzene, 8.6 parts by mass of high cis butadiene rubber 13HB manufactured by Ube Industries as a rubber-like polymer (E-2), and 0.02 parts by mass of 1,1-bis(t-butylperoxy)cyclohexane were charged into a raw material tank equipped with a stirrer, and after dissolving the rubber components with a stirrer, this raw material solution was supplied to the reactor at a volume of 0.75 liters / hr, and polymerization was carried out at a temperature of 110 to 120°C in the first stage reactor, 120 to 130°C in the second stage reactor, and 140 to 150°C in the third stage reactor. The extruder temperature was 210-240°C, the degree of vacuum was 3 kPa, and the total solid content in the polymerization liquid discharged from the final reactor was 70.5% by mass. The average particle size of the rubber-like polymer particles (E-2) was controlled by adjusting the rotation speed of the stirrer of the first-stage laminar flow reactor to 110 rpm. The composition and properties of the obtained resin (E1) are shown in Table 4.

[0226] -Preparation of resin (E2)- Resin (E2) having the composition and physical properties shown in Table 4 was obtained in the same manner as above, except that high cis butadiene rubber 15HB manufactured by Ube Industries was used as the rubber-like polymer (E-2).

[0227] -Preparation of resin (E3)- Resin (E3) having the composition and physical properties shown in Table 4 was obtained in the same manner as above using styrene, methyl methacrylate, and butyl acrylate as monomers and Asahi Kasei styrene-butadiene copolymer 625A as rubber-like polymer (E-2).

[0228] -Preparation of resin (E4)- Resin (E4) having the composition and physical properties shown in Table 4 was obtained in the same manner as above using high cis butadiene rubber 15HB manufactured by Ube Industries as the rubber-like polymer (E-2), and styrene and methyl methacrylate as monomers.

[0229] [Table 4]

[0230] <Styrene-based elastomer (F) used in the examples> In the examples of this specification, the following two types of styrene-based elastomer (F) were used. (F1) Asahi Kasei styrene-butadiene block copolymer Tufprene 125 (F2) Asahi Kasei styrene-butadiene block copolymer Tuftec M1913

[0231] <(Meth)acrylonitrile-diene-styrene resin (G) used in the examples> The outline of the preparation method of the (meth)acrylonitrile-diene-styrene resin (G) used in this embodiment is to first prepare a resin (G-2-1) containing butadiene-styrene-acrylonitrile graft copolymer particles (rubber-like polymer particles (G-2)) at a high concentration, and then knead and dilute the separately prepared styrene-acrylonitrile copolymer (G-1-1) and the butadiene-styrene-acrylonitrile graft copolymer particles (G-2-1) (corresponding to rubber-like polymer particles (G-2)), and adjust the concentration of the rubber-like polymer particles (G-2) and the polymer matrix (G-1) to a desired value. Below, a specific example of the preparation method will be described.

[0232] -Preparation of Resin (G1) (ABS Resin G1)- To 122 parts by mass of polybutadiene rubber latex (average particle size 0.280 μm, solid content 37% by mass), 0.1 parts by mass of tertiary dodecyl mercaptan and 23 parts by mass of deionized water were added, the gas phase was replaced with nitrogen, and the temperature was raised to 55° C. Next, while raising the temperature to 70° C. over 1.5 hours, an aqueous solution obtained by dissolving 0.2 parts by mass of sodium formaldehyde sulfoxylate, 0.004 parts by mass of ferrous sulfate, and 0.04 parts by mass of disodium ethylenediaminetetraacetic acid in 50 parts by mass of deionized water was added over 4 hours to a monomer mixture consisting of 14 parts by mass of acrylonitrile, 37 parts by mass of styrene, 0.5 parts by mass of tertiary dodecyl mercaptan, and 0.15 parts by mass of cumene hydroperoxide. After completion of the addition, 0.02 parts by mass of cumene hydroperoxide was added, and the polymerization reaction was completed for another hour while controlling the reaction tank at 70° C.

[0233] A silicone resin defoamer (manufactured by Momentive Performance Materials Japan, LLC, product name TSA737) and a phenolic antioxidant emulsion (manufactured by Chukyo Yushi Co., Ltd., product name L-673) were added to the mixture of styrene-acrylonitrile copolymer and butadiene-styrene-acrylonitrile graft copolymer thus obtained. Then, deionized water was added to adjust the solid content concentration to 10% by mass, and the mixture was heated to 70°C. Then, an aqueous aluminum sulfate solution was added to coagulate the mixture, and solid-liquid separation was performed using a screw press machine. The water content at this time was 10% by mass. This was dried to obtain a resin (G-2-1) containing a high concentration of butadiene-styrene-acrylonitrile graft copolymer particles.

[0234] As a result of composition analysis, the composition ratio of the above resin (G-2-1) was 17% by mass of acrylonitrile, 45% by mass of butadiene, and 38% by mass of styrene. The butadiene-styrene-acrylonitrile graft copolymer was in the form of particles like the polybutadiene rubber latex, and the average particle size was 0.30 μm. On the other hand, a monomer mixture consisting of 63 parts by mass of styrene, 22 parts by mass of acrylonitrile, and 15 parts by mass of ethylbenzene was continuously fed to a complete mixing reactor equipped with a stirrer, and a polymerization reaction was carried out at 150°C and a residence time of 2 hours. The obtained polymerization solvent was continuously fed to an extruder, and unreacted monomers and solvent were recovered using a devolatilizing extruder to obtain a styrene-acrylonitrile copolymer (G-1-1). The composition of the copolymer (C-1-1) was 30% by mass of acrylonitrile and 70% by mass of styrene as a result of composition analysis using a Fourier transform infrared spectrophotometer (FR-IR) (manufactured by JASCO Corporation).

[0235] The resin (G-2-1) containing a high concentration of butadiene-styrene-acrylonitrile graft copolymer particles (rubber-like polymer particles (G-2)) obtained by the above procedure and the styrene-acrylonitrile copolymer (G-1-1) were extrusion-kneaded and pelletized in a twin-screw extruder to obtain ABS resin (G1) as a pellet-shaped ABS resin. The composition and physical properties of the obtained ABS resin (G1) are shown in Table 5.

[0236] -Preparation of Resin (G2) (ABS Resin G2)- The feed amount of each monomer and the polymerization conditions were adjusted to prepare resin (G-2-1) in the same manner as the above ABS resin (G1), and then 90 parts by mass of ABS resin and 10 parts by mass of styrene-acrylonitrile-N-phenylmaleimide copolymer were extrusion-kneaded and pelletized in a twin-screw extruder to obtain ABS resin (G2) as a pellet-shaped ABS compound resin. The composition and physical properties of the obtained ABS resin (G2) are shown in Table 5.

[0237] [Table 5]

[0238] <Production example of acrylic resin (H)> -Preparation of resin (H1)- 2 kg of water, 65 g of tribasic calcium phosphate, 39 g of calcium carbonate, and 0.39 g of sodium lauryl sulfate were added to a 5 L container equipped with an agitator, and the mixture was mixed and stirred to prepare a suspension. Next, 26 kg of water was added to a 60 L reactor, and the temperature was raised to 80°C to prepare for suspension polymerization. After confirming that the temperature had reached 80°C and was in a constant temperature state, 1.52 kg of methyl methacrylate, 0.04 kg of methyl acrylate, 0.99 g of lauroyl peroxide, 4.93 g of n-octyl mercaptan, and the above suspension were added as polymerization raw materials. Then, the suspension polymerization was carried out while maintaining the temperature at about 80°C, and after observing the exothermic peak, the temperature was raised to 92°C at a rate of 1°C / min and the temperature was maintained at 92°C for 60 minutes. Then, after cooling to 50°C, 20% by mass of sulfuric acid was added to dissolve the suspension. The polymerization reaction solution was then removed from the 60 L reactor and passed through a sieve with a mesh size of 1.7 mm to remove large aggregates, after which the aqueous layer and solid matter were separated in a Buchner funnel to obtain a bead-like polymer. The bead-like polymer was washed and dehydrated five times with about 20 L of distilled water on the Buchner funnel, then dried and pelletized using a single-screw extruder to obtain resin (H1) as a pellet-like resin. The composition and physical properties of the obtained resin (H1) are shown in Table 6.

[0239] -Preparation of Resin (H2) and Resin (H3)- Resins (H2) to (H6) were prepared in the same manner as for the above resin (H1) by adjusting the polymerization conditions. The compositions and physical properties of the obtained resins (H2) to (H6) are shown in Table 6.

[0240] [Table 6]

[0241] <Antioxidants used in the Examples> In the examples of the present specification, the following two types of antioxidants were used as antioxidants. Antioxidant-1: Irganox 1076 manufactured by BASF Japan Compound name: Octadecyl-3-(3,5-tert-butyl-4-hydroxyphenyl)propionate Antioxidant-2: Irgafos168 manufactured by BASF Japan Compound name: Tris(2,4-di-tert-butylphenyl)phosphite

[0242] <<Production Examples of Styrene-Based Resin Compositions and Extruded Sheets>> The detailed production method of the styrene-based resin composition and the extruded sheet will be described below. [Example 1] -Production of styrene-based resin composition- 90.0 parts by mass of resin (A1) shown in Table 1 as styrene-unsaturated carboxylic acid resin (A), 10.0 parts by mass of resin (B1) shown in Table 2 as (meth)acrylic resin (B), and 0.14 parts by mass of Fine Oxocol 180 were dry-blended, and the mixture was kneaded, extruded, and pelletized using a twin-screw extruder TEM26SS manufactured by Shibaura Machine Co., Ltd. to obtain a styrene resin composition [1] as a pellet-shaped resin. The screw rotation speed was 150 rpm, the cylinder temperature was 180 to 230 ° C, and the feed rate was 10 kg / h. The resin temperature was 250 to 260 ° C. The evaluation results of the properties and physical properties of the styrene resin composition [1] are shown in Table 7.

[0243] -Production of (non-foamed) continuous extrusion sheets- The styrene-based resin composition [1] obtained above was fed to an extruder equipped with a vacuum vent and capable of nitrogen purge. The maximum cylinder temperature of the extruder was set to 250°C. The resin composition extruded from the T-die was wound on a mirror-finished metal roll, and a non-foamed extruded sheet [1] with a thickness of 0.25 mm was produced by adjusting the winding speed and the amount of resin discharged. The evaluation results of the obtained non-foamed extruded sheet [1] are shown in Table 7.

[0244] -Production of (non-foamed) continuous extruded biaxially oriented sheets- The styrene-based resin composition [1] obtained above was fed to an extruder that could be purged with nitrogen and had a vacuum vent. The maximum cylinder temperature of the extruder was set to 250°C. The resin composition extruded from the T-die was stretched 2.5 times in the MD direction while being wound on a mirror-finished metal roll, and then stretched 2.5 times in the TD direction with a tenter, thereby performing biaxial stretching. By adjusting the winding speed and the discharge amount of the resin, a biaxially stretched sheet [1] with a thickness of 0.22 mm was produced. The evaluation results of the obtained biaxially stretched sheet [1] and the lid-shaped body obtained by secondary molding of the biaxially stretched sheet [1] are shown in Table 7.

[0245] - Manufacturing of foam extrusion sheets - 100 parts by mass of the styrene resin composition [1] obtained above and 1.0 part by mass of talc (Hifiller #12 manufactured by Matsumura Sangyo Co., Ltd.) as inorganic fine particles were dry blended and fed to an extruder. The maximum cylinder temperature of the extruder was set to 250°C. 4.0 parts by mass of mixed butane with a mass ratio of isobutane / normal butane of 65 / 35 as a foaming agent was pressed into the melt-kneaded resin composition per 100 parts by mass of the styrene resin composition [1], extruded into a cylindrical shape from a circular die, and foamed. The obtained cylindrical foam was cooled by blowing air onto it, and then cooled by a cooling mandrel, and cut open the cylindrical foam in the extrusion direction to obtain a foamed extruded sheet [1]. The evaluation results of the obtained foamed extruded sheet [1] and the evaluation results of the foamed container obtained by secondary molding of the foamed extruded sheet [1] are shown in Table 7 (collectively referring to Tables 7-1, 7-2 and 7-3, the same below).

[0246] [Examples 2 to 39] Styrenic resin compositions [2] to

[39] and extruded sheets [2] to

[39] were obtained in the same manner as in Example 1, except that the formulation was changed as shown in the following Table 7. The evaluation results of the obtained styrenic resin compositions [2] to

[39] and extruded sheets [2] to

[39] , as well as the evaluation results of the lid-like bodies and containers obtained by secondary molding of the extruded sheets, are shown in Table 7.

[0247] [Table 7-1]

[0248] [Table 7-2]

[0249] [Table 7-3]

[0250] [Comparative Examples 1 to 4] Resin compositions and extruded sheets were obtained in the same manner as in Example 1, except that the mixing ratio was changed as shown in Table 8 below. Table 8 shows the evaluation results of the obtained resin compositions and extruded sheets, as well as the evaluation results of the lid-like bodies and containers obtained by secondary molding of the extruded sheets.

[0251] [Table 8] [Industrial Applicability]

[0252] The styrene-based resin composition obtained by the present invention has excellent heat resistance, mechanical strength, and low-temperature strength. Therefore, the styrene-based resin composition of the present invention can be widely used for non-foamed or foamed sheets by extrusion molding, food packaging containers using them, or molded products by injection molding (electrical product parts, toys, daily necessities, various industrial parts), and is particularly useful as a packaging material that can be transported and stored at low temperatures and can be cooked in a microwave oven. In other words, it is useful in efforts to reduce food waste, and can be said to be a material with low environmental impact. Therefore, it plays a large role in the industrial world.

Claims

1. 48.0% by mass or more and 97% by mass or less of a styrene-unsaturated carboxylic acid-based resin (A) having a styrene-based monomer unit (1) and an unsaturated carboxylic acid-based monomer unit (a1); A styrene-based resin composition comprising: 3% by mass or more and 21% by mass or less of a (meth)acrylic resin (B) having a (meth)acrylic acid ester monomer unit (b1); The (meth)acrylic acid ester monomer unit (b1) is composed of one or more monomer units selected from the group consisting of (meth)acrylic acid ester monomer units (b1-0) having an ester substituent with 1 carbon atom, and (meth)acrylic acid ester monomer units (b1-1) having an ester substituent with 4 to 8 carbon atoms, the content of the styrene-based monomer unit (1) is 84.0 to 92 mass% based on the total amount of the styrene-unsaturated carboxylic acid-based resin (A), the content of the (meth)acrylic acid ester monomer unit (b1-1) in the (meth)acrylic resin (B) is more than 35 mass% based on the total amount of the (meth)acrylic resin (B); A styrene-based resin composition comprising either of the following (a) or (b): (A) An embodiment in which the styrene-based resin composition is composed only of the styrene-unsaturated carboxylic acid-based resin (A) and the (meth)acrylic resin (B), the content of the styrene-unsaturated carboxylic acid-based resin (A) relative to the total amount (100 mass%) of the styrene-based resin composition is 79 to 97 mass%, and the content of the (meth)acrylic resin (B) relative to the total amount (100 mass%) of the styrene-based resin composition is 3 to 21 mass%, (A) The styrene-based resin composition contains the styrene-unsaturated carboxylic acid-based resin (A) and the (meth)acrylic resin (B), and further contains a monohydric alcohol (C) having 10 or more carbon atoms, a core-shell type rubber-like polymer particle (D) containing a (meth)acrylic acid ester monomer unit (d1) and a conjugated diene-based monomer unit (d2), an impact-resistant styrene-based resin (E) containing a styrene-based monomer unit (e1) and a conjugated diene-based monomer unit (e2), a styrene-based elastomer (F), a styrene-based monomer unit (g1), a conjugated diene-based monomer unit (g2), and a (meth)acrylic acid ester monomer unit (g3). and one or more selected from the group consisting of a (meth)acrylonitrile-diene-styrene-based resin (G) containing an acrylonitrile-based monomer unit (g3), an acrylic resin (H) having more than 40 mass% of a (meth)acrylic acid ester monomer unit (h1), and an additive component, and the total content of the styrene-unsaturated carboxylic acid-based resin (A), the (meth)acrylic resin (B), the (meth)acrylonitrile-diene-styrene-based resin (G), the acrylic resin (H) and the additive component in the styrene-based resin composition is 85 to 100 mass%.

2. The styrene-based resin composition according to claim 1, wherein the content of the (meth)acrylic acid ester monomer unit (b1-1) is more than 45 mass% based on the total amount of the (meth)acrylic resin (B).

3. 3. The styrene-based resin composition according to claim 1 or 2, wherein the (meth)acrylic resin (B) is a block copolymer and comprises one or more selected from the group consisting of a methacrylic polymer block (B1) having a methyl methacrylate monomer content of 90 mass% or more and an acrylic polymer block (B2) having an acrylic ester monomer unit content of 90 mass% or more.

4. The styrene-based resin composition according to claim 1 or 2, wherein the (meth)acrylic resin (B) is any one of a methyl methacrylate-butyl acrylate copolymer, a methyl methacrylate-acrylic (2-ethylhexyl) copolymer, and a methyl methacrylate-acrylic (butyl acrylate-acrylic (2-ethylhexyl)) copolymer.

5. The styrene-based resin composition according to claim 1 or 2, further comprising 0.001 to 1.0 part by mass of a monohydric alcohol (C) having 10 or more carbon atoms relative to the total amount (100 parts by mass) of the styrene-based resin composition.

6. 3. The styrene-based resin composition according to claim 1, wherein a high molecular weight component having a molecular weight of 1,000,000 or more in the entire styrene-based resin composition is 5.0 mass% or less based on the total amount of the styrene-based resin composition.

7. The styrene-based resin composition according to claim 1 or 2, wherein the unsaturated carboxylic acid-based monomer unit (a1) is at least one selected from the group consisting of (meth)acrylic acid monomer units (a1-1) and (meth)acrylic acid ester monomer units (a1-2).

8. The unsaturated carboxylic acid monomer unit (a1) contains two essential components, namely, a (meth)acrylic acid monomer unit (a1-1) and a (meth)acrylic acid ester monomer unit (a1-2), The styrene-based resin composition according to claim 1 or 2, comprising 2 to 30 mass% of the (meth)acrylic acid monomer unit (a1-1) and 0.01 to 20 mass% of the (meth)acrylic acid ester monomer unit (a1-2) relative to the total amount of the styrene-unsaturated carboxylic acid-based resin (A).

9. The composition further comprises one or more selected from the group consisting of core-shell type rubber-like polymer particles (D) containing (meth)acrylic acid ester monomer units (d1) and conjugated diene monomer units (d2), impact resistant styrene resins (E) containing styrene monomer units (e1) and conjugated diene monomer units (e2), styrene elastomers (F), (meth)acrylonitrile-diene-styrene resins (G) containing styrene monomer units (g1), conjugated diene monomer units (g2) and (meth)acrylonitrile monomer units (g3), and acrylic resins (H) having more than 40 mass% of (meth)acrylic acid ester monomer units (h1), 3. The styrene-based resin composition according to claim 1, wherein the content of the (meth)acrylic acid ester monomer unit (b1-1) contained in the (meth)acrylic acid ester monomer unit (h1) is 35 mass% or less based on the total amount of the acrylic resin (H).

10. The styrene-unsaturated carboxylic acid resin (A), the (meth)acrylic resin (B), the (meth)acrylonitrile-diene-styrene resin (G), and the acrylic resin (H). The styrene-based resin composition according to claim 9.

11. A non-foamable or foamable extruded sheet comprising the styrene-based resin composition according to claim 1 or 2.

12. A container obtained by molding the styrene-based resin composition according to claim 1 or 2.

13. 3. An injection molded article obtained by injection molding the styrene-based resin according to claim 1 or 2.

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