Styrenic resin composition, foamed extruded sheet and container

Abstract

To provide a styrenic resin composition which is excellent in moldability without lowering heat resistance and impact resistance, an extrusion sheet using the same, and a container which is obtained by secondary molding of the extrusion sheet.SOLUTION: A styrenic resin composition contains 50-98 mass% of a styrene-unsaturated carboxylic acid-based resin (A) having a styrenic monomer unit (a1) and an unsaturated carboxylic acid-based monomer unit (a2), and 2-50 mass% of a (meth)acrylic resin (B) having an unsaturated carboxylic acid-based monomer unit (b1), wherein elongation viscosity (MPa s) of the styrenic resin composition at a temperature of 160°C, strain viscosity of 1.0 / s and a Henky strain of 0.5 is 0.6 MPa s or less.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present disclosure relates to a styrene-based resin composition, a foamed extruded sheet molded using the styrene-based resin composition, and a food container formed by secondary molding of the foamed 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 the containers. However, the strength and moldability of these resins are inferior to those of general-purpose styrene resins, which is an issue. For example, Patent Document 1 describes a technique for improving mechanical strength while maintaining practical heat resistance by using a mixture of a styrene-methacrylic acid copolymer and a polyethylene resin. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2014-80562 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the technology of the above-mentioned Patent Document 1, mechanical strength is considered, but moldability and container appearance are not considered. In addition, since conventional styrene-unsaturated carboxylic acid copolymer resins tend to be easily cracked during foam sheet molding and container molding due to their high melt viscosity and brittleness, there is a demand for compatibility between mechanical strength and moldability. Therefore, the present disclosure has an object to provide a styrene-based resin composition having excellent heat resistance, mechanical strength and moldability. Another object of the present disclosure is to provide a foamed extruded sheet containing a molded styrene-based resin composition having excellent heat resistance, mechanical strength and moldability, and a food container obtained by secondary molding of the foamed extruded sheet. [Means for solving the problem]

[0005] Means for Solving the Problems The present inventors have intensively investigated the above problems and conducted repeated experiments, and as a result, have found that the above problems can be solved by setting the extensional viscosity of a styrene-based resin composition comprising a specific styrene-unsaturated carboxylic acid-based resin (A) and a specific (meth)acrylic resin (B) in combination to a certain value or less, thereby completing the present invention. [1] The present disclosure relates to a styrene-based resin composition containing 50 to 98 mass% of a styrene-unsaturated carboxylic acid-based resin (A) having a styrene-based monomer unit (a1) and an unsaturated carboxylic acid-based monomer unit (a2), and more than 0 to 50 mass% of a (meth)acrylic resin (B) having an unsaturated carboxylic acid-based monomer unit (b1), wherein the elongational viscosity (MPa s) of the styrene-based resin composition is 0.6 MPa s or less at a temperature of 160°C, a strain rate of 1.0 / s, and a Hencky strain of 0.5. [2] The styrene-based resin composition according to the above [1], wherein the (meth)acrylic resin (B) has an ethylene monomer unit. [3] The styrene-based resin composition according to the above [1] or [2], wherein a value obtained by dividing a melt tension (gf) of the styrene-based resin composition at a temperature of 220°C and a take-up speed of 3.1 m / min by an extensional viscosity (MPa s) of the styrene-based resin composition at a temperature of 160°C, a strain rate of 1.0 / s, and a Hencky strain of 0.5 is 16 or more.

[0006] [4] The styrene-based resin composition according to any one of the above [1] to [3], further comprising a high melt tension, low viscosity component having an effect of improving the melt tension of the styrene-based resin composition by 5% or more and / or having an effect of decreasing the elongational viscosity of the styrene-based resin composition by 5% or more.

[0007] [5] The styrene-based resin composition according to any one of the above [1] to [4], wherein the unsaturated carboxylic acid-based monomer unit (a2) contains one or more selected from the group consisting of (meth)acrylic acid monomer units (a2-1) and (meth)acrylic acid ester monomer units (a2-2).

[0008] [6] The styrene-unsaturated carboxylic acid resin (A) contains, as essential components, the styrene monomer unit (a1), the (meth)acrylic acid monomer unit (a2-1), and the (meth)acrylic acid ester monomer unit (a2-2), The styrene-based resin composition according to any one of the above [1] to [5], wherein the styrene-unsaturated carboxylic acid-based resin (A) contains 2 to 30 mass% of the (meth)acrylic acid monomer unit (a2-1) and 1 to 20 mass% of the (meth)acrylic acid ester monomer unit (a2-2) based on the entirety of the styrene-unsaturated carboxylic acid-based resin (A).

[0009] [7] The styrene-based resin composition according to any one of [1] to [6] above, wherein the content of all (meth)acrylic acid ester monomer units contained in the styrene-based resin composition is 10 to 50 mass% based on the total amount of the styrene-based resin composition.

[0010] [8] The styrene-based resin composition according to any one of the above [1] to [7], wherein the (meth)acrylic resin (B) is a copolymer consisting of methyl methacrylate monomer units and one or more types of monomer units other than methyl methacrylate, and contains 10 to 98 mass% of methyl methacrylate monomer units based on the total amount of the copolymer.

[0011] [9] The styrene-based resin composition according to any one of the above [1] to [8], wherein the (meth)acrylic resin (B) has four or more inflection points in a differential molecular weight distribution curve.

[0012]

[10] The styrene-based resin composition according to any one of [1] to [9] above, wherein when the styrene-based resin composition is divided into a first molecular weight component of 10,000 or less and a second molecular weight component of more than 10,000, the first molecular weight component is 0.5 to 3.0 mass% of the total amount of the styrene-based resin composition.

[0013]

[11] The styrene-based resin composition according to any one of the above [1] to

[10] , further comprising inorganic particles (H) in an amount of 0.05 to 3.0% by mass relative to the total amount of the styrene-based resin composition.

[0014]

[12] One aspect of the present embodiment is a foamed extruded sheet obtained by molding the styrene-based resin composition described in any one of the above [1] to

[11] , the foamed extruded sheet having a closed cell ratio of 80% or more and an average thickness in the range of 0.5 to 3.0 mm.

[0015]

[13] One aspect of this embodiment is a foamed container obtained by secondary molding of the foamed extruded sheet described in

[12] above. Effect of the Invention

[0016] 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 moldability. According to the present disclosure, it is possible to provide a foamed extruded sheet having excellent heat resistance, mechanical strength, and moldability, and a foamed container that can be used for microwave cooking. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] 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 in this embodiment (hereinafter, sometimes simply referred to as a resin composition) contains a styrene-unsaturated carboxylic acid-based resin (A) having a styrene-based monomer unit (a1) and an unsaturated carboxylic acid-based monomer unit (a2), and a (meth)acrylic resin (B) having an unsaturated carboxylic acid-based monomer unit (b1), and the content of the styrene-unsaturated carboxylic acid-based resin (A) is 50 to 98 mass%, and the content of the (meth)acrylic resin (B) is more than 0 mass% and 50 mass% or less, relative to the total amount (100 mass%) of the styrene-based resin composition. The extensional viscosity (EV described below) of the styrene-based resin composition is 0.6 or less. In addition, the melt tension (MT described below) / extensional viscosity (EV described below) value of the styrene-based resin composition is preferably 16 or more. This makes it possible to obtain a resin that is easy to stretch when melted and difficult to break, and thus to obtain a foamed extruded sheet with high moldability. In this specification, the extensional viscosity (MPa s) of the styrene-based resin composition at a temperature of 160°C, a strain rate of 1.0 / s, and a Hencky strain of 0.5 is also referred to as "EV", and the melt tension (gf) of the styrene-based resin composition at a temperature of 220°C and a take-up speed of 3.1 m / min is also referred to as "MT". The EV of the styrene-based resin composition in this embodiment is 0.6 MPa·s or less, preferably 0.59 MPa·s or less, more preferably 0.58 MPa·s or less, even more preferably 0.57 MPa·s or less, even more preferably 0.56 MPa·s or less, still more preferably 0.55 MPa·s or less, and most preferably 0.53 MPa·s or less. The lower limit is preferably 0.15 MPa·s or more, more preferably 0.10 MPa·s or more, even more preferably 0.15 MPa·s or more, and most preferably 0.20 MPa·s or more. By controlling the EV of the styrene-based resin composition in this embodiment particularly within the range of 0.15 to 0.6 MPa·s, a styrene-based resin composition in which the resin is more easily elongated when melted can be obtained. In the present embodiment, the MT / EV value of the styrene-based resin composition is preferably 16 to 400. When the MT / EV is 16 or more, the molten resin is less likely to break, and a foamed extruded sheet with higher moldability can be obtained. On the other hand, when the MT / EV value is 400 or less, the melt tension is in a moderate range, and the effect of excellent moldability is exhibited. On the other hand, when the EV is more than 0.6 MPa·s and the MT / EV value is more than 400, the melt tension becomes excessively high, which rather leads to deterioration of moldability. Therefore, by setting the MT / EV in the range of 18 to 70, a styrene-based resin composition with particularly excellent moldability and a foamed extruded sheet and a molded product obtained by molding the same can be obtained. Hereinafter, each component and physical properties of the styrene-based resin composition of the present disclosure will be described in detail.

[0018] "Styrene-unsaturated carboxylic acid resin (A)" The styrene-unsaturated carboxylic acid resin (A) in this embodiment is a copolymer resin (hereinafter also referred to as resin (A)) consisting essentially of a styrene monomer unit (a1) and an unsaturated carboxylic acid monomer unit (a2), and contributes to improving the heat resistance of the entire styrene resin composition. The unsaturated carboxylic acid monomer unit (a2) is preferably one or more monomer units selected from the group consisting of (meth)acrylic acid monomer units (a2-1) and (meth)acrylic acid ester monomers (a2-2). The styrene-unsaturated carboxylic acid resin (A) may contain a styrene monomer unit, if necessary. In addition to the essential components (a1) and unsaturated carboxylic acid monomer units (a2) (e.g., one or more monomer units selected from the group consisting of (meth)acrylic acid monomer units (a2-1) and (meth)acrylic acid ester monomer units (a2-2)), other monomer units (a3) ​​may be further contained. The content of the styrene-unsaturated carboxylic acid resin (A) is 50 to 98 mass%, preferably 53 to 97 mass%, more preferably 55 to 96 mass%, and even more preferably 60 to 95 mass%, based on the total amount (100 mass%) of the styrene-based resin composition. By making the content of the styrene-unsaturated carboxylic acid resin (A) 50 mass% or more, the effect of imparting heat resistance can be sufficiently obtained, and by making it 98 mass% or less, the effect of improving mechanical strength by the (meth)acrylic resin (B) described below can be sufficiently obtained. The styrene-unsaturated carboxylic acid resin (A) of the present embodiment is preferably a random copolymer or an alternating copolymer.

[0019] <Styrene-based monomer (a1)> In the styrene-unsaturated carboxylic acid resin (A) of this embodiment, the content of the styrene-based monomer unit (a1) is 60 to 98 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 (a1) is less than 60 mass%, the flowability is reduced, and if it is more than 98 mass%, it becomes difficult to contain the desired amount of the unsaturated carboxylic acid monomer (a2) (especially the (meth)acrylic acid monomer unit (a2-1) described later), and in particular, the effect of improving heat resistance by the (meth)acrylic acid monomer unit (a2-1) is not sufficiently obtained. In the styrene-based resin composition of the present embodiment, the styrene-based monomer unit (a1) is preferably contained in an amount of 45 to 85 mass%, more preferably 48 to 82 mass%, more preferably 52 to 79 mass%, and even more preferably 56 to 77 mass%, based on the total amount of the styrene-based resin composition. When the content of the styrene-based monomer (a1) in the entire composition is within the above range, the effect of improving heat resistance can be sufficiently obtained.

[0020] In this embodiment, the styrene-based monomer (a1) 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 (a1), these may be used alone or in combination of two or more. In this specification, the term "styrene monomer unit (a1)" refers to a repeating unit constituting a polymer obtained by polymerizing a styrene monomer (a1), and is a repeating unit (or structural unit) in which the carbon-carbon double bond in the styrene monomer (a1) becomes a single bond (-CC-) through a polymerization reaction or crosslinking reaction of the styrene monomer (a1). Other monomer units in this specification have the same meaning.

[0021] <Unsaturated carboxylic acid monomer (a2)> In the styrene-unsaturated carboxylic acid resin (A) of this embodiment, the unsaturated carboxylic acid monomer unit (a2) plays a role in improving heat resistance, oil resistance, and compatibility with the (meth)acrylic resin (B) described below. The content of the unsaturated carboxylic acid monomer unit (a2) is 2 to 40 mass%, preferably 3 to 35 mass%, more preferably 5 to 30 mass%, even more preferably 8 to 25 mass%, and most preferably 10 to 20 mass% relative to the total amount of the styrene-unsaturated carboxylic acid resin (A). If the content of the unsaturated carboxylic acid monomer unit (a2) is less than 2 mass%, the effect of improving heat resistance is insufficient. In addition, if the content of the unsaturated carboxylic acid monomer unit (a2) exceeds 40 mass%, it is not preferable because the processability decreases due to the increase in resin viscosity and the generation of bubbles during molding due to the increase in water absorption rate becomes a problem. In particular, by adjusting the content of the unsaturated carboxylic acid monomer unit (a2) to 10 to 20 mass %, good compatibility with the (meth)acrylic resin (B) can be obtained, and a composition with excellent transparency can be obtained. In addition, the unsaturated carboxylic acid monomer unit (a2) in this embodiment includes an unsaturated carboxylic acid and its ester, and specifically includes a (meth)acrylic acid monomer unit (a2-1) and a (meth)acrylic acid ester monomer unit (a2-2).

[0022] <<(Meth)acrylic acid monomer (a2-1)>> In the styrene-unsaturated carboxylic acid resin (A) of this embodiment, the (meth)acrylic acid monomer unit (a2-1) plays a role in improving oil resistance and compatibility with the (meth)acrylic resin (B) described below. When the styrene-unsaturated carboxylic acid resin (A) of this embodiment contains the (meth)acrylic acid monomer unit (a2-1), the content of the (meth)acrylic acid monomer unit (a2-1) is preferably 2 to 40 mass%, more preferably 3 to 35 mass%, more preferably 5 to 30 mass%, even more preferably 8 to 25 mass%, and most preferably 10 to 20 mass%, based on the total amount of the styrene-unsaturated carboxylic acid resin (A). In another embodiment, the content of the (meth)acrylic acid monomer unit (a2-1) is preferably 3 to 20 mass%, more preferably 4 to 17 mass%, and even more preferably 8 to 14 mass%. If the content of the (meth)acrylic acid monomer unit (a2-1) is less than 2% by mass, the effect of improving heat resistance is insufficient. If the content of the (meth)acrylic acid monomer unit (a2-1) is more than 40% by mass, the resin viscosity increases, which leads to a decrease in processability, and the water absorption rate increases, which leads to bubbles during molding, and the viscosity becomes too high during production, which is not preferable. By making the content of the (meth)acrylic acid monomer unit (a2-1) 2% by mass or more, the effect of improving heat resistance can be obtained, and by making the content 40% by mass or less, the viscosity can be prevented from increasing too much. In particular, by making the content of the (meth)acrylic acid monomer unit (a2-1) 8 to 25% by mass, good compatibility with the (meth)acrylic resin (B) can be obtained, and the effect of improving the strength and melt tension during kneading with the (meth)acrylic resin (B) can be efficiently obtained.

[0023] In this embodiment, the (meth)acrylic acid monomer unit (a2-1) plays a role in improving heat resistance. Examples of the (meth)acrylic acid monomer (a2-1) include acrylic acid and methacrylic acid. From an industrial viewpoint, the (meth)acrylic acid monomer unit (a2-1) may be used alone or in combination of two or more. As the (meth)acrylic acid monomer unit (a2-1), methacrylic acid, which has a large effect of improving heat resistance, is particularly preferred.

[0024] <<(Meth)acrylic acid ester monomer (a2-2)>> In this embodiment, the styrene-unsaturated carboxylic acid resin (A) may further contain a (meth)acrylic acid ester monomer (a2-2). The (meth)acrylic acid ester monomer (a2-2) plays a role in improving oil resistance and strength. The (meth)acrylic acid ester monomer (a2-2) is a monomer represented by the following general formula (1): [ka] (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. In this embodiment, the ester substituent of the (meth)acrylic acid ester monomer unit (a2-2) (R 2 The number of carbon atoms in the ester substituent is preferably 10 or less, more preferably 8 or less, and even more preferably 4 or less. If the number of carbon atoms in the ester substituent exceeds 10, the effect of lowering heat resistance is significant, which is not preferred.

[0025] In the present embodiment, the (meth)acrylic acid ester monomer (a2-2) may, for example, be methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, cyclohexyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, or decyl (meth)acrylate. These may be used alone or in combination. As the (meth)acrylic acid ester monomer (a2-2), 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. In this embodiment, when the styrene-unsaturated carboxylic acid resin (A) of this embodiment contains the (meth)acrylic acid ester monomer unit (a2-2), the content of the (meth)acrylic acid ester monomer unit (a2-2) is preferably 2 to 40 mass%, more preferably 3 to 32 mass%, more preferably 3 to 20 mass%, even more preferably 3 to 17 mass%, still more preferably 3 to 12 mass%, and even more preferably 4 to 10 mass% relative to the total amount of the styrene-unsaturated carboxylic acid resin (A). By making the content of the (meth)acrylic acid ester monomer unit (a2-2) 2 to 40 mass%, good compatibility with the (meth)acrylic resin (B) can be obtained, and the strength and melt tension improvement effect during kneading with the (meth)acrylic resin (B) can be efficiently obtained.

[0026] <Preferable form of styrene-unsaturated carboxylic acid resin (A)> The styrene-unsaturated carboxylic acid resin (A) of this embodiment may be a multipolymer containing a (meth)acrylic acid monomer unit (a2-1) and a (meth)acrylic acid ester monomer unit (a2-2). That is, the styrene-unsaturated carboxylic acid resin (A) of this embodiment may be a binary copolymer of a styrene monomer unit (a1) and a (meth)acrylic acid monomer unit (a2-1), a ternary copolymer in which a styrene monomer (a1), a (meth)acrylic acid monomer (a2-1), and a (meth)acrylic acid ester monomer (a2-2) are copolymerized, or a ternary copolymer containing a styrene monomer unit (a1) and two kinds of (meth)acrylic acid monomer units (a2-1). This further improves the compatibility with the (meth)acrylic resin (B), improves the surface hardness, or improves the mechanical strength. In particular, when emphasis is placed on improving heat resistance and surface hardness, the styrene-unsaturated carboxylic acid resin (A) preferably contains a (meth)acrylic acid monomer unit (a2-1). In particular, when emphasis is placed on improving appearance and mechanical strength, the styrene-unsaturated carboxylic acid resin (A) preferably contains a (meth)acrylic acid ester monomer unit (a2-2). Furthermore, when emphasis is placed on improving compatibility with the (meth)acrylic resin (B) and on high transparency in a mixture with the resin (B), the styrene-unsaturated carboxylic acid resin (A) is preferably a ternary copolymer in which the styrene monomer unit (a1), the (meth)acrylic acid monomer unit (a2-1), and the (meth)acrylic acid ester monomer unit (a2-2) are copolymerized. In addition, when an unsaturated carboxylic acid ester monomer unit such as the (meth)acrylic acid ester monomer unit (a2-2) is arranged adjacent to an unsaturated carboxylic acid monomer unit such as the (meth)acrylic acid unit (a2-1) in a polymer chain, an effect such as suppressing a crosslinking reaction between unsaturated carboxylic acids can be obtained. The styrene-unsaturated carboxylic acid resin (A) in this embodiment is a styrene monomer unit (a1), a (meth)acrylic acid monomer unit (a2-1), and a (meth)acrylic acid ester monomer unit (a2-2). In the case where the styrene-unsaturated carboxylic acid resin (A) has a (meth)acrylic acid monomer unit (a2-1), the content of the (meth)acrylic acid ester monomer unit (a2-2) is preferably 2 to 30 mass% and the content of the (meth)acrylic acid ester monomer unit (a2-2) is preferably 0 to 20 mass%, more preferably 2 to 30 mass% and the content of the (meth)acrylic acid ester monomer unit (a2-1) is preferably 0 to 20 mass%, based on the total amount of the styrene-unsaturated carboxylic acid resin (A). The content of the monomer unit (a2-2) is 1 to 20 mass%, more preferably, the content of the (meth)acrylic acid monomer unit (a2-1) is 2 to 25 mass%, and the content of the (meth)acrylic acid ester monomer unit (a2-2) is 1.5 to 15 mass%, and even more preferably, the content of the (meth)acrylic acid monomer unit (a2-1) is 2 to 20 mass%, and the content of the (meth)acrylic acid ester monomer unit (a2-2) is 2 to 13 mass%. By restricting the content of the (meth)acrylic acid ester monomer unit (a2-2) to 20 mass% or less, it is possible to obtain a composition having low elongation viscosity and high moldability.

[0027] <<Other monomers (a3)>> The styrene-unsaturated carboxylic acid resin (A) in this embodiment may further have other monomer units (a3) ​​other than the above-mentioned styrene monomer units (a1) and the (meth)acrylic acid monomer units (a2-1) and / or (meth)acrylic acid ester monomer units (a2-2). That is, in this embodiment, the other monomer unit (a3) ​​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 unit (a1), the (meth)acrylic acid monomer unit (a2-1) and / or the (meth)acrylic acid ester monomer unit (a2-2) within a range that does not impair the effects of the invention. For example, examples of the other monomer (a3) ​​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. In the present embodiment, when the styrene-unsaturated carboxylic acid resin (A) contains the other monomer (a3), the content of the other monomer (a3) ​​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.

[0028] <Characteristics of styrene-unsaturated carboxylic acid resin (A)> The contents of the styrene-based monomer unit (a1), the (meth)acrylic acid monomer unit (a2-1), the (meth)acrylic acid ester monomer unit (a2-2) and the other monomer unit (a3) ​​in the styrene-unsaturated carboxylic acid resin (A) in this embodiment can be quantified using a calibration curve prepared using a resin in which each monomer unit is known, using pyrolysis GC / MS. 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.

[0029] The weight average molecular weight (Mw) of the styrene-unsaturated carboxylic acid resin (A) in this embodiment is preferably 100,000 to 350,000, and 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. On the other hand, the number average molecular weight (Mn) of the styrene-unsaturated carboxylic acid resin (A) is preferably in the range of 40,000 to 150,000, more preferably 50,000 to 120,000, and even more preferably 60,000 to 110,000. The weight average molecular weight and number average molecular weight can be measured by gel permeation chromatography (GPC) in terms of polystyrene standard.

[0030] 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 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.

[0031] <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 (a1), an unsaturated carboxylic acid monomer (a2) (e.g., a (meth)acrylic acid monomer (a2-1) and / or a (meth)acrylic acid ester monomer (a2-2)), 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. 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.

[0032] 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.

[0033] 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.

[0034] The polymerization method of the styrene-unsaturated carboxylic acid resin (A) can be solution polymerization using a polymerization solvent. 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. 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. Furthermore, when the monohydric alcohol 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 monohydric alcohol having 10 or more carbon atoms in a proportion of 1 to 10 mass % relative to 100 mass % of the total polymerization solvent.

[0035] 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.

[0036] "(Meth)acrylic resin (B)" The styrene-based resin composition in this embodiment contains more than 0 mass% and 50 mass% or less of (meth)acrylic resin (B) (also simply referred to as resin (B)) relative to the total amount of the styrene-based resin composition. The (meth)acrylic resin (B) contains one or more types of unsaturated carboxylic acid monomer units (b1), preferably (meth)acrylic acid ester monomer units (b1-2). The inclusion of a predetermined amount of (meth)acrylic resin (B) contributes to improving the mechanical strength of the entire styrene-based resin composition. In this specification, the (meth)acrylic resin (B) is a general term for synthetic resins having a styrene monomer unit content of 40 mass% or less and an unsaturated carboxylic acid monomer unit (b1) content of more than 2 mass%, and preferably a synthetic resin having a (meth)acrylic acid ester monomer unit (b1-2) content of more than 2 mass%. The (meth)acrylic resin (B) is preferably a random copolymer. In addition, styrene-unsaturated carboxylic acid resin (A), (meth)acrylonitrile-diene-styrene resin (C), impact resistant styrene resin (D), styrene elastomer (E), acrylic elastomer (F) and core-shell type rubber polymer particles (G) are excluded from (meth)acrylic resin (B).

[0037] The content of the (meth)acrylic resin (B) is more than 0 to 50 mass%, more preferably 2 to 48 mass%, even more preferably 10 to 46 mass%, still more preferably 14 to 45 mass%, and most preferably 19 to 35 mass%, relative to the total amount (100 mass%) of the styrene-based resin composition. By making the content of the (meth)acrylic resin (B) more than 0, particularly 2 to 46 mass%, it is possible to suppress a decrease in the heat resistance improved by the styrene-unsaturated carboxylic acid-based resin (A). In the present embodiment, when a resin containing an olefin monomer unit and an unsaturated carboxylic acid monomer unit (b1) (for example, resin (B-4) or resin (B-7) described in the Examples) is used as the (meth)acrylic resin (B), the content of the resin containing an olefin monomer unit and an unsaturated carboxylic acid monomer unit (b1) relative to the total amount (100 mass%) of the styrene resin composition is more than 0 to 20 mass%, more preferably 2 to 18 mass%, even more preferably 3 to 16 mass%, still more preferably 4 to 13 mass%, and most preferably 5 to 10 mass%. By setting the content of the resin containing the olefin monomer unit and the unsaturated carboxylic acid monomer unit (b1) to 2% by mass or more and 20% by mass or less, the compatibility of the entire styrene-based resin composition is maintained, which contributes to improving moldability. The unsaturated carboxylic acid monomer unit (b1) constituting the (meth)acrylic resin (B) of this embodiment preferably essentially contains one or more repeating units selected from the group consisting of (meth)acrylic acid monomer units (b1-1) and (meth)acrylic acid ester monomer units (b1-2), more preferably contains (meth)acrylic acid ester monomer units (b1-2), and further preferably is a random copolymer containing repeating units containing two or more types of (meth)acrylic acid ester monomer units (b1-2). In this embodiment, the upper limit of the total content of the (meth)acrylic acid ester monomer unit (b1-2) and the (meth)acrylic acid monomer unit (b1-1) 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 more than 0% by mass, 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 total content of the (meth)acrylic acid ester monomer unit (b1-2) and the (meth)acrylic acid monomer unit (b1-1) can be arbitrarily combined with the above upper limit and the above lower limit. The (meth)acrylic acid ester monomer unit (b1-2) and the (meth)acrylic acid monomer unit (b1-1) of this embodiment will be described below.

[0038] <(Meth)acrylic acid ester monomer (b1-2)> The (meth)acrylic acid ester monomer unit (b1-2) 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, the (meth)acrylic acid ester monomer (b1-2) 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. The (meth)acrylic acid ester monomers (b1-2) can be used alone or in combination, and it is preferable to use two kinds of (meth)acrylic acid ester monomers (b1-2) in combination. As a preferred embodiment of the unsaturated carboxylic acid monomer unit (b1) constituting the (meth)acrylic resin (B) of the present embodiment, from the viewpoint of achieving both heat resistance and thermal decomposition property, it is preferred to contain two kinds of (meth)acrylic acid ester monomers (b1-2) among the monomer units listed above, more preferred is a combination in which a methacrylic acid ester species and an acrylic acid ester species are copolymerized, and even more preferred is a methyl methacrylate-methyl acrylate copolymer. In this embodiment, the upper limit of the content of the (meth)acrylic acid ester monomer unit (b1-2) 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 this order, based on the total amount of the (meth)acrylic resin (B). 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 this order. The content of the (meth)acrylic acid ester monomer unit (b1-2) can be arbitrarily combined with the above upper limit and the above lower limit. The range of the content of the (meth)acrylic acid ester monomer unit (b1-2) is, for example, preferably 0 to 100% by mass, more preferably 2 to 99% by mass, even more preferably 3 to 98% by mass, even more preferably 4 to 98% by mass, even more preferably 5 to 98% by mass, and particularly preferably 6 to 98% by mass.

[0039] <(Meth)acrylic acid monomer (b1-1)> In this embodiment, the (meth)acrylic acid monomer (b1-1) may be acrylic acid or methacrylic acid. In this embodiment, the upper limit of the content of the (meth)acrylic acid monomer unit (b1-1) 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. 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. The content of the (meth)acrylic acid monomer unit (b1-1) can be arbitrarily combined with the above upper limit and the above lower limit.

[0040] <Other monomers (b2)> The (meth)acrylic resin (B) of this embodiment may further have other monomer units (b2) other than the above-mentioned (meth)acrylic acid monomer units (b1-1) and (meth)acrylic acid ester monomer units (b1-2). That is, the other monomers (b2) 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 (b1-1) and / or the (meth)acrylic acid ester monomer (b1-2) within a range that does not impair the effects of the invention. For example, other monomers (b2) other than the above-mentioned monomers include olefins (olefin monomers) such as styrene, ethylene, or propylene, maleic anhydride, maleic acid, fumaric acid, itaconic acid, dimethyl maleate, dimethyl fumarate, diethyl fumarate, ethyl fumarate, maleimide, and nucleus-substituted maleimide. A preferred embodiment of the other monomer unit (b2) in this embodiment may be an olefin-based monomer unit (for example, an ethylene monomer unit, a propylene monomer unit). In this embodiment, the content of the other monomer units (b2) is preferably 0 to 90 mass%, more preferably 0 to 85 mass%, even more preferably 0 to 80 mass%, still more preferably 0 to 70 mass%, even more preferably 0 to 60 mass%, and even more preferably 0 to 50 mass%, relative to the total amount of the (meth)acrylic resin (B).

[0041] <Preferable form of (meth)acrylic resin (B)> The (meth)acrylic resin (B) of the present embodiment is preferably a binary or tertiary copolymer.

[0042] In the (meth)acrylic resin (B) of this embodiment, the content of the (meth)acrylic acid ester monomer unit (b1-2) in the (meth)acrylic resin (B) is preferably 2.0 to 100 mass% based on the total amount of the (meth)acrylic resin (B), more preferably 5.0 to 99.5 mass%, even more preferably 8.0 to 98.5 mass%, and even more preferably 10 to 98.0 mass%. By setting the content of the (meth)acrylic acid ester monomer (b1-2) in the range of 10.0 to 100 mass%, it becomes possible to withstand kneading extrusion and molding with other resins at 300°C or less. Therefore, it is possible to suppress a significant decrease in heat resistance when the styrene-unsaturated carboxylic acid resin (A) and the (meth)acrylic resin (B) are mixed. As the type of (meth)acrylic acid ester monomer (b1-2), methyl acrylate or methyl methacrylate is preferable because of its heat resistance, industrial availability, and low cost. A preferred embodiment of the (meth)acrylic resin (B) of this embodiment is a copolymer containing methyl methacrylate monomer units and one or more types of monomer units other than the methyl methacrylate monomer units. The monomer units other than the methyl methacrylate monomer units literally include not only other monomer units (b2) and (meth)acrylic acid monomer units (b1-1), but also (meth)acrylic acid ester monomers (b1-2) other than the methyl methacrylate monomer units.

[0043] The (meth)acrylic resin (B) of this embodiment contains an ethylene monomer unit as a monomer unit. When it does not contain an olefin monomer unit such as , the weight average molecular weight (Mw) of the (meth)acrylic resin (B) is preferably 50,000 to 5,000,000, more preferably 60,000 to 1,000,000, even more preferably 70,000 to 300,000, and even more preferably 80,000 to 200,000. By making the weight average molecular weight (Mw) of the (meth)acrylic resin (B) 50,000 or more, it is possible to impart strength and melt tension when kneaded with the styrene-unsaturated carboxylic acid resin (A), and by making the weight average molecular weight (Mw) 5,000,000 or less, it is possible to suppress the viscosity difference with the styrene-unsaturated carboxylic acid resin (A), and the (meth)acrylic resin (B) can be well dispersed in the styrene resin composition, and the generation of unmelted matter derived from the (meth)acrylic resin (B) can be suppressed, and a molded product such as a foamed extruded sheet with good appearance can be obtained using the composition. In the present invention, 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 of 10,000 or less in the styrene resin composition are values ​​measured using gel permeation chromatography (GPC), as described in the Examples section below.

[0044] In addition, the (meth)acrylic resin (B) of this embodiment is preferably a resin having four or more inflection points in the differential molecular weight distribution curve. The molecular weight distribution of a general resin is monodisperse, and the number of inflection points in the differential molecular weight distribution curve is two. In this specification, a resin having four or more inflection points in the differential molecular weight distribution curve means a resin having two or more maximum points in the differential molecular weight distribution curve, and for example, a resin having a bimodal molecular weight distribution may fall under this category. In this specification, the term "differential molecular weight distribution curve" refers to a curve in which the vertical axis is "dw / dLog(M)" (a value obtained by differentiating the concentration fraction by the logarithm of the molecular weight) when determining the molecular weight distribution curve of the (meth)acrylic resin (B) by the SEC method, where w represents the concentration fraction and M represents the molecular weight. The (meth)acrylic resin (B) preferably has an Mw / Mn value of 1.5 or more, more preferably 1.7 or more, and even more preferably 3.0 or more. By incorporating a (meth)acrylic resin (B) having four or more inflection points in a differential molecular weight distribution curve and a wide molecular weight distribution into a styrene-based resin composition, the viscosity of the styrene-based resin composition can be kept low by the low molecular weight component, while the melt tension can be improved by the effect of the polymer component.

[0045] In addition, when the styrene-based resin composition of this embodiment is divided into a first molecular weight component having a molecular weight of 10,000 or less and a second molecular weight component having a molecular weight of more than 10,000, it has been confirmed that when a predetermined amount of the first molecular weight component having a molecular weight of 10,000 or less is contained in the styrene-based resin composition, the extensional viscosity of the molten resin becomes lower and the moldability tends to be improved. The ratio of the first molecular weight component having a molecular weight of 10,000 or less in this embodiment is preferably in the range of 0.3 to 3.0 mass% with respect to the total amount of the styrene-based resin composition. More preferably, it is in the range of 0.7 to 2.6 mass%, further preferably 0.9 to 2.5 mass%, and most preferably 1.0 to 2.1 mass%. If the amount of the first molecular weight component is less than 0.5 mass%, the extensional viscosity of the molten resin becomes high and the moldability decreases. On the other hand, if the amount of the first molecular weight component is more than 3.0 mass%, the mechanical strength of the molded product decreases due to the presence of an excessive amount of low molecular weight components. By setting the amount of the first molecular weight component to 0.5 to 3.0 mass%, a styrene-based resin composition that gives a foamed extruded sheet with excellent mechanical strength and moldability can be obtained. The amount of the first molecular weight component having a molecular weight of 10,000 or less was determined by using gel permeation chromatography (GPC) to measure the molecular weight in terms of standard polystyrene using a calibration curve method using standard polystyrene, and calculating the proportion of components having a molecular weight of 10,000 or less in the entire composition from the molecular weight distribution obtained. In a preferred embodiment of the present invention, the styrene-based resin composition contains a (meth)acrylic resin (B) having four or more inflection points in a differential molecular weight distribution curve and a wide molecular weight distribution, whereby the proportion of low molecular weight components is increased and the first molecular weight component having a molecular weight of 10,000 or less in the matrix polymer portion of the styrene-based resin composition is increased.

[0046] <Method for producing (meth)acrylic resin (B)> The method for producing the (meth)acrylic resin (B) of the present embodiment is not particularly limited, and the (meth)acrylic resin (B) can be produced by a process such as bulk polymerization in which the unsaturated carboxylic acid monomer unit (b1) is polymerized with other monomers 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.

[0047] "Ratio of melt tension to elongational viscosity" In this embodiment, a styrene-based resin composition having excellent moldability and a foamed extruded sheet and molded article obtained by molding the same are obtained by setting the ratio of melt tension to elongational viscosity (MT / EV) of the styrene-based resin composition in the range described below. In order to obtain a resin having excellent moldability, it is necessary to achieve both the ease of stretching the molten resin and the resistance to cutting the molten resin.

[0048] The melt tension (MT) of the styrene resin composition in this embodiment is a physical property value adopted as an index of the difficulty of cutting the molten resin, specifically, a measured value (gf) at a temperature of 220 ° C. and a take-up speed of 3.1 m / min. The MT of the styrene resin composition in this embodiment is preferably 5.0 gf or more, more preferably 6.0 gf or more, even more preferably 7.0 gf or more, even more preferably 8.0 gf or more, even more preferably 8.5 gf or more, and most preferably 10.0 gf or more. The upper limit of the MT is preferably 130 gf or less, more preferably 80 gf or less, even more preferably 40 gf or less, even more preferably 30 gf or less, and most preferably 20 gf or less. By controlling the MT of the styrene resin composition in this embodiment within the range of 5 to 130 gf, a styrene resin composition in which the resin is difficult to cut when melted can be obtained. The extensional viscosity (EV) of the styrene-based resin composition in this embodiment is a physical property value adopted as an index of the elongation of the molten resin, specifically, a measured value (MPa·s) at a temperature of 160°C, a strain rate of 1.0 / s, and a Hencky strain of 0.5. The EV of the styrene-based resin composition in this embodiment is 0.6 MPa·s or less, preferably 0.59 MPa·s or less, more preferably 0.58 MPa·s or less, even more preferably 0.57 MPa·s or less, even more preferably 0.56 MPa·s or less, even more preferably 0.55 MPa·s or less, and most preferably 0.53 MPa·s or less. The lower limit is preferably 0.15 MPa·s or more, more preferably 0.10 MPa·s or more, even more preferably 0.15 MPa·s or more, and most preferably 0.20 MPa·s or more. By controlling the EV of the styrene-based resin composition of this embodiment to a range of 0.15 to 0.6 MPa·s, a styrene-based resin composition in which the resin is more easily elongated when melted can be obtained. Effective means for setting the EV of the styrene-based resin composition to 0.6 MPa·s or less include the following (a) to (d). (a) The content of the (meth)acrylic resin (B) is more than 0 and 46 mass % based on the total amount of the styrene-based resin composition. (b) The content of a first molecular weight component having a molecular weight of 10,000 or less in the matrix polymer portion of the styrene-based resin composition is 0.5 to 3.0 mass %. (c) The styrene-based resin composition contains 10% by mass or more of a (meth)acrylic resin (B) having four or more inflection points in a differential molecular weight distribution curve, based on the total amount of the styrene-based resin composition. (d) The styrene resin composition contains one or more high melt tension, low viscosity components. As described above, by taking one or more of the measures (1) to (4), it becomes easy to control the EV of the styrene-based resin composition to 0.6 MPa·s or less.

[0049] In the present embodiment, the ratio of melt tension to elongational viscosity (MT / EV) of the styrene-based resin composition is preferably 16.0 or more, more preferably 16.6 or more, even more preferably 16.8 or more, still more preferably 18.0 or more, and even more preferably 19.5 or more. The upper limit of the melt tension ratio is preferably 400 or less, more preferably 300 or less, even more preferably 200 or less, still more preferably 100 or less, and most preferably 70 or less. When MT / EV is 16 or more, the molten resin is not easily cut, and the problem of the resin being cut during molding is not likely to occur. In particular, when EV is more than 0.6 MPa·s and MT / EV is less than 16, the molten resin is easily cut, and the problem of the resin being cut during molding is not preferable. On the other hand, when EV is more than 0.6 MPa·s and the value of MT / EV is more than 400, the load required to stretch the resin during molding becomes excessively large, which leads to deterioration of moldability. In this embodiment, in order to obtain a resin with excellent moldability, it is necessary to balance the ease of stretching the molten resin and the difficulty of cutting the molten resin. By setting MT / EV in the range of 16 to 400, a styrene-based resin composition with excellent moldability in which the molten resin is moderately easy to stretch and difficult to cut, and a foamed extrusion sheet and a molded product obtained by molding the same can be obtained.

[0050] In the present embodiment, the following (1) to (10) can be mentioned as effective means for setting the ratio of melt tension to extensional viscosity (MT / EV) of the styrene-based resin composition within a preferred range.

[0051] (1) The content of the (meth)acrylic resin (B) is more than 0 to 46 mass % based on the total amount of the styrene-based resin composition. (2) The content of all (meth)acrylic acid ester monomer units contained in the styrene-based resin composition is 10 to 50 mass % based on the total amount of the styrene-based resin composition. (3) The weight average molecular weight (Mw) of the (meth)acrylic resin (B) is set within the range of 50,000 to 5,000,000. (4) The content of a first molecular weight component having a molecular weight of 10,000 or less in the matrix polymer portion of the styrene-based resin composition is 0.5 to 3.0 mass %. (5) The styrene resin composition contains 10% by mass or more of a (meth)acrylic resin (B) having four or more inflection points in a differential molecular weight distribution curve, based on the total amount of the styrene resin composition. (6) The styrene-based resin composition contains one or more high melt tension, low viscosity components. (7) The content of the (meth)acrylic acid monomer unit (a2-1) is 8 to 25 mass % based on the total amount of the styrene-unsaturated carboxylic acid resin (A). (8) The content of the (meth)acrylic acid ester monomer units (a2-2) is 2 to 20 mass % based on the total amount of the styrene-unsaturated carboxylic acid resin (A). (9) The weight average molecular weight of the styrene-unsaturated carboxylic acid resin (A) is 100,000 to 350,000. (10) The content of the monohydric alcohol having 10 or more carbon atoms is 0.01 to 1.0 mass % based on the total amount of the styrene-based resin composition. By taking one or more of the measures (1) to (10) above, it becomes easier to control the ratio of melt tension to extensional viscosity (MT / EV) of the styrene-based resin composition within a preferred range.

[0052] "Other ingredients" The styrene-based resin composition in the present embodiment may contain, as necessary, one or more optional components selected from the group consisting of a high melt tension and low viscosity component, inorganic particles (H), a monohydric alcohol having 10 or more carbon atoms, and an optional additive component.

[0053] <High melt tension, low viscosity component> The styrene-based resin composition in the embodiment may contain one or more high melt tension and low viscosity components as necessary. The high melt tension and low viscosity components are additives having the effect of increasing the MT of the styrene-based resin composition by 5% or more and / or decreasing the EV of the styrene-based resin composition by 5% or more. Specifically, (meth)acrylonitrile-diene-styrene-based resin (C), impact resistant styrene-based resin (D), styrene-based elastomer (E), and the like. Examples of the styrene-based resin composition include (meth)acrylonitrile-diene-styrene-based resin (C), high-impact styrene-based resin (D), styrene-based elastomer (E), acrylic elastomer (F), and core-shell type rubbery polymer particles (G). This increases the ratio of melt tension to elongational viscosity (MT / EV) of the styrene-based resin composition, improving the moldability of the solid sheet and the foamed sheet. In other words, from the viewpoint of improving the moldability, the styrene-based resin composition in the embodiment preferably contains one or more selected from the group consisting of (meth)acrylonitrile-diene-styrene-based resin (C), high-impact styrene-based resin (D), styrene-based elastomer (E), acrylic elastomer (F), and core-shell type rubbery polymer particles (G).

[0054] <(Meth)acrylonitrile-diene-styrene resin (C)> 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 (C) (also simply referred to as resin (C)) containing (meth)acrylonitrile-based monomer units (c3), conjugated diene-based monomer units (c2) and styrene-based monomer units (c1). When the styrene-based resin composition contains an appropriate amount of the (meth)acrylonitrile-diene-styrene-based resin (C), a styrene-based resin composition capable of forming molded articles having excellent strength can be obtained. The (meth)acrylonitrile-diene-styrene-based resin (C) of the present embodiment refers to a resin obtained by dispersing rubber-like polymer particles (=rubber-like polymer particles (C2)) mainly composed of conjugated diene-based monomer units (c2) in a polymer matrix (C1) containing a copolymer obtained by polymerizing (meth)acrylonitrile-based monomer units (c3), a styrene-based monomer (c1), and other monomer components as necessary, and other resins blended as necessary, and may be, for example, a so-called ABS resin. In other words, the (meth)acrylonitrile-diene-styrene resin (C) of this embodiment contains a polymer matrix (C1) and rubber-like polymer particles (C2). The polymer matrix (C1) contains a copolymer obtained by polymerizing (meth)acrylonitrile-based monomer units (c3), a styrene-based monomer (c1), and other monomer components blended as necessary, and other resins blended as necessary. The rubber-like polymer particles (C2) are particles of a rubber-like polymer mainly composed of conjugated diene-based monomer units (c2). In this specification, the term "mainly composed" means that the conjugated diene monomer unit (c2) (e.g., butadiene monomer unit (c2)) constitutes 50% by mass or more of the entire rubber polymer particle (C2).

[0055] Examples of the styrene monomer (c1) 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 (c1) may be used alone or in combination of two or more kinds.

[0056] Examples of the conjugated diene monomer unit (c2) of this embodiment include 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 1,3-hexadiene, etc., and from an industrial viewpoint, 1,3-butadiene is preferred. The conjugated diene monomer unit (c2) may be used alone or in combination of two or more kinds.

[0057] Examples of the (meth)acrylonitrile-based monomer unit (c3) include an acrylonitrile unit and a methacrylonitrile unit. Among these, an acrylonitrile unit is preferred from an industrial viewpoint. The (meth)acrylonitrile-based monomer unit (c3) may be used alone. Either one or more of them may be used in combination.

[0058] <<Preferable form of (meth)acrylonitrile-diene-styrene resin (C)>> The mass ratio of the (meth)acrylonitrile monomer unit (c3) to the styrene monomer unit (c1) in the polymer matrix (C1) constituting the (meth)acrylonitrile-diene-styrene resin (C) is preferably (meth)acrylonitrile monomer unit (c3) / styrene monomer unit (c1)=5 / 95-40 / 60, more preferably 10 / 90-35 / 65, more preferably 15 / 85-30 / 70, and most preferably 20 / 80-25 / 75. In particular, by making the mass ratio in the range of 20 / 80-30 / 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.

[0059] The content of the rubber-like polymer particles (C2) mainly composed of the conjugated diene monomer unit (c2) constituting the (meth)acrylonitrile-diene-styrene-based resin (C) is preferably 5 to 40 mass %, more preferably 10 to 35 mass %, and further preferably 15 to 30 mass % based on the total amount of the (meth)acrylonitrile-diene-styrene-based resin (C). By setting the content of the rubber-like polymer particles (C2) in the range of 5 to 40 mass %, an excellent balance between rigidity and impact resistance is achieved when added to a styrene-based resin composition.

[0060] The average particle size of the rubber-like polymer particles (C2) of the (meth)acrylonitrile-diene-styrene resin (C) 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 resin composition is excellent in the effect of improving the 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. In addition, a preferred embodiment of the rubber-like polymer particle (C2) may have a structure in which a solid rubber-like particle having conjugated diene monomer units (c2) as a constituent component is used as a core, and the core is coated with a polymer containing styrene-based monomer units (c1) and (meth)acrylonitrile-based monomer units (c3) so as to cover the core.

[0061] The polymer matrix (C1) of the (meth)acrylonitrile-diene-styrene resin (C) may contain other polymers in an amount of 25% by mass or less based on the total amount of the (meth)acrylonitrile-diene-styrene resin (C) in addition to the copolymer mainly composed of the (meth)acrylonitrile monomer unit (c3) and the styrene monomer (c1). For example, the heat resistance of the (meth)acrylonitrile-diene-styrene resin (C) may be improved by adding a styrene-acrylonitrile-N-phenylmaleimide copolymer or the like.

[0062] In this embodiment, the melt flow rate of the (meth)acrylonitrile-diene-styrene resin (C) 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.

[0063] <<Production method of (meth)acrylonitrile-diene-styrene resin (C)>> The (meth)acrylonitrile-diene-styrene resin (C) can be produced by a process in which a resin that is the main component of the polymer matrix (C1) prepared in advance by radical bulk polymerization or solution polymerization is mixed with ABS rubber-like polymer particles ( There are methods for preparing the rubber-like polymer particles (C2) and the polymer matrix (C1) simultaneously, such as the impact-resistant styrene-based resin (D) described below, and the most suitable method can be selected according to need. The difference between the (meth)acrylonitrile-diene-styrene resin (C) and the impact-resistant styrene resin (D) described below is the content of the (meth)acrylonitrile monomer unit. That is, the content of the (meth)acrylonitrile monomer unit in the former (meth)acrylonitrile-diene-styrene resin (C) is more than 3 mass% based on the total amount of the (meth)acrylonitrile-diene-styrene resin (C). On the other hand, the content of the (meth)acrylonitrile monomer unit in the impact-resistant styrene resin (D) described below is 3 mass% or less based on the total amount of the impact-resistant styrene resin (D).

[0064] <Impact-resistant styrene resin (D)> In a preferred embodiment of the present invention, the styrene resin composition preferably contains an impact-resistant styrene resin (D) (also simply referred to as resin (D)). By containing an appropriate amount of the rubber-modified styrene resin (D), a styrene resin composition capable of producing a molded article having excellent strength can be obtained. The rubber-modified styrene-based resin (D) of this embodiment may be a so-called high impact polystyrene resin (HIPS resin) obtained by dispersing particles of a rubber-like polymer (D2) (=rubber-like polymer particles (D2)) in a polymer matrix (D1) of a resin consisting of a styrene-based monomer unit (d1) and other monomer units (d3) that are included as necessary, and polymerizing the styrene-based monomer (d1) in the presence of the rubber-like polymer (D2). In other words, the impact-resistant styrene-based resin (D) of this embodiment contains a polymer matrix (D1) and rubber-like polymer particles (D2). The polymer matrix (D1) contains a polymer obtained by polymerizing the styrene-based monomer (d1) and other monomers (d3) that are blended as necessary. The rubber-like polymer particles (D2) are particles of a rubber-like polymer (D2) mainly composed of conjugated diene monomer units (d2), and the surface of the particles may be grafted with a polymer containing styrene monomer units (d1) as necessary.

[0065] The content of the impact resistant styrene resin (D) 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 (D) in the range of 3 to 15 mass%, a styrene resin composition having better strength can be obtained.

[0066] <<Rubber-like polymer particles (D2)>> In this embodiment, the rubber-like polymer (D2) constituting the rubber-like polymer particles (D2) in the impact-resistant styrene-based resin (D) is preferably formed from a conjugated diene-based monomer (d2), and more preferably is a polymer having a conjugated diene-based monomer unit (d2). Specific examples of the rubber-like polymer (D2) that can be used include polybutadiene, polyisoprene, natural rubber, polychloroprene, styrene-butadiene copolymer, acrylonitrile-butadiene copolymer, etc., 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. In the present specification, the term "conjugated diene monomer" is a general term for the above-mentioned conjugated diene monomer (c2), conjugated diene monomer (d2) and conjugated diene monomer (e2). In addition, in the present specification, the term "rubber-like polymer particles" refers to the rubber-like polymer particles (C2) and the rubber-like polymer particles (C3). A general term for child (D2). 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. In the present embodiment, the rubber-like polymer particles (D2) preferably contain a polymer containing a styrene-based monomer unit (d1) or a polymer containing the styrene-based monomer unit (d1) and another monomer (d3) in a dispersed particle of the rubber-like polymer (D2). 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 (d1) are contained in the rubber-like polymer (D2). <<Other monomers (d3)>> Examples of the other monomer (unit) (d3), which is an optional component of the impact resistant styrene-based resin (D) of this embodiment, include (meth)acrylic acid ester 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. In this embodiment, the content of the other monomer (unit) (d3) in the impact resistant styrene-based resin (D) 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 (D).

[0067] <<Content of conjugated diene monomer units (d2)>> In this embodiment, the content of the conjugated diene monomer unit (d2) in the impact resistant styrene resin (D) 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 (D). The content of the conjugated diene monomer unit (d2) in the impact resistant styrene resin (D) and the styrene resin composition can be measured by the procedure described in the Examples section below or a method equivalent thereto.

[0068] <<Average particle size of rubber-like polymer particles (D2)>> The rubber-like polymer (D2) which is the rubber component in the impact-resistant styrene-based resin (D) in this embodiment is present as particles of the rubber-like polymer (D2) in the styrene-based resin composition. In this case, the average particle size of the rubber-like polymer particles (D2) 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 (D) is obtained by polymerizing a styrene-based monomer (d1) in a reactor equipped with a stirrer in the presence of the rubber-like polymer particles (D2), and the average particle size of the rubber-like polymer particles (D2) can be adjusted by the number of revolutions of the stirrer, the molecular weight of the rubber-like polymer (D2) used, and the like. In the present disclosure, the average particle size of the rubber-like polymer particles (D2) 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 (D2) are stretched during foaming in a foamed sheet described below, and the particle size increases by about 150 to 400%.

[0069] In this embodiment, the melt flow rate of the impact resistant styrene resin (D) 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-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.

[0070] <<Production method of impact-resistant styrene resin (D)>> The method for producing the impact-resistant styrene-based resin (D) is not particularly limited, but it can be produced by bulk polymerization (or solution polymerization) in which a styrene-based monomer (d1) and, if necessary, other monomers (d3) and a solvent are polymerized in the presence of a rubber-like polymer (D2), bulk-suspension polymerization that transitions to suspension polymerization during the reaction, or emulsion graft polymerization in which a styrene-based monomer (d1) is polymerized in the presence of latex particles that are a rubber-like polymer (D2). In bulk polymerization, the rubber-like polymer (D2), the styrene-based monomer (d1), and, if necessary, other monomers (d3), 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.

[0071] <Styrene-based elastomer (E)> In a preferred embodiment of this embodiment, the styrene-based resin composition further contains a styrene-based elastomer (E) (also simply referred to as elastomer (E)). The styrene-based elastomer (E) 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) (e1) and a soft block of a conjugated diene-based monomer (unit) (e2). As the elastomer (E), a block copolymer having a hard block of a styrene-based monomer (unit) (e1) and a soft block of a butadiene monomer unit is more preferred. The styrene monomer (e1) may be the same as the styrene monomer (a1) described above, and the conjugated diene monomer (e2) may be the same as the conjugated diene monomer (c2) described above.

[0072] Examples of the chain structure of the block copolymer of the styrene-based elastomer (E) include a styrene-based monomer (e1)-butadiene diblock type, a styrene-based monomer (e1)-butadiene-styrene-based monomer (e1) triblock type, and a butadiene-styrene-based monomer (e1)-butadiene triblock type. From the viewpoint of improving mechanical strength, the styrene-based monomer (e1)-butadiene-styrene-based monomer (e1) triblock type is preferred.

[0073] As for the content of the styrene monomer unit (e1) and the conjugated diene monomer unit (e2) constituting the styrene elastomer (E), the content of the styrene monomer unit (e1) is preferably 30 to 70 mass%, more preferably the content of the styrene monomer unit (e1) is 35 to 65 mass%, and the content of the conjugated diene monomer unit (e2) is the remainder of 100 mass%. If the content of the styrene monomer unit (e1) is 35 to 65%, the dispersibility in the styrene-unsaturated carboxylic acid resin (A) is appropriately improved, and a product excellent in mechanical strength and appearance can be obtained. Methods for producing the styrene-based elastomer (E) such as styrene-butadiene elastomer include radical polymerization, anionic polymerization, and polymer reaction methods, with the anionic polymerization being preferred from the industrial viewpoint.

[0074] When the content of the conjugated diene monomer (e2) in the styrene-based elastomer (E) exceeds 50% by mass, the content of the styrene-based elastomer (E) in the styrene-based composition of the present 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 (e2) in the styrene-based elastomer (E) is 50% by mass or less, the content of the styrene-based elastomer (E) 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 mechanical strength when added to the styrene-based resin composition. The difference between styrene-based elastomer (E) and acrylic-based elastomer (F) described below is The styrene-based elastomers (E) and (F) have different contents of styrene-based monomer units. That is, the content of styrene-based monomer units in the former styrene-based elastomer (E) exceeds 3 mass% based on the total amount of the styrene-based elastomer (E). On the other hand, the content of styrene-based monomer units in the acrylic elastomer (F) described below is 3 mass% or less based on the total amount of the acrylic elastomer (F).

[0075] <Acrylic elastomer (F)> In a preferred embodiment of this embodiment, the styrene-based resin composition preferably contains an acrylic elastomer (F) (also simply referred to as elastomer (F)). The acrylic elastomer (F) used in the resin composition of the present invention is a block copolymer having a hard block of methyl methacrylate monomer units (f1) and a soft block of acrylic ester monomer units (f2). As the acrylic elastomer (F), a block copolymer having a hard block of methyl methacrylate monomer (unit) and a soft block of acrylic ester monomer units (f2) is more preferred. Thus, the acrylic elastomer (F) is a block copolymer, whereas the (meth)acrylic resin (B) is a random polymer or an alternating polymer, and thus the two are different from each other. Examples of the acrylic acid ester monomer (f2) include the same monomers as the acrylic acid ester monomer units among the (meth)acrylic acid ester monomer units (b1) described above.

[0076] Examples of the chain structure of the block copolymer of the acrylic elastomer (F) include a methyl methacrylate-acrylic acid ester (f2) block type, a methyl methacrylate-acrylic acid ester (f2)-methyl methacrylate triblock type, and an acrylic acid ester (f2)-methyl methacrylate-acrylic acid ester (f2) triblock type. From the viewpoint of improving mechanical strength, the methyl methacrylate-acrylic acid ester (f2)-methyl methacrylate triblock type is preferred.

[0077] Regarding the content of the methyl methacrylate monomer (f1) and the acrylic acid ester monomer (f2) constituting the acrylic elastomer (F), the content of the methyl methacrylate monomer (f1) is preferably 20 to 65 mass%, more preferably 30 to 55 mass%, while the content of the acrylic acid ester monomer (f2) is the remainder of 100 mass%. When the content of the methyl methacrylate monomer (f1) is 20 to 65%, the dispersibility in the styrene-unsaturated carboxylic acid resin (A) is appropriately improved, and a product excellent in mechanical strength and appearance can be obtained.

[0078] The content of the acrylic elastomer (F) in the styrene-based composition of the present embodiment is preferably 0.5 to 20 mass%, more preferably 1 to 17 mass%, and even more preferably 2 to 15 mass%, relative to the total amount of the styrene-based resin composition. By setting the content in the range of 0.5 to 20 mass%, it is possible to suppress a decrease in heat resistance and improve mechanical strength when added to a styrene-based resin composition.

[0079] <Core-shell type rubber polymer particles (G)> As a preferred aspect of this embodiment, the styrene-based resin composition of this embodiment preferably further contains core-shell type rubbery polymer particles (G) (also simply referred to as core-shell particles (G)) formed by grafting a copolymer containing a styrene-based monomer unit (g2-1) and / or a (meth)acrylic acid ester monomer unit (g2-2) to a rubbery particle (corresponding to a core portion) containing a conjugated diene-based monomer unit (g1-1) or a (meth)acrylic acid ester monomer unit (g1-2). The core-shell type rubbery polymer particles (G) of this embodiment have a rubbery particle containing a conjugated diene monomer unit (g1-1) or a (meth)acrylic acid ester monomer unit (g1-2) as a core part, and a shell part that at least partially covers the core part contains a styrene monomer unit (g2-1) and / or a (meth)acrylic acid ester monomer unit (g2-2). In other words, at least a part of the core portion is covered with a graft copolymer containing a styrene-based monomer unit (g2-1) and / or a (meth)acrylic acid ester monomer unit (g2-2). The number of the core portion is preferably one.

[0080] The content of the core-shell type rubbery polymer particles (G) 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. The conjugated diene monomer (g1-1) constituting the rubber particles of the core-shell type rubber polymer particles (G) 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. Examples of the (meth)acrylic acid ester monomer units (g1-2) constituting the rubber particles of the core-shell type rubber polymer particles (G) include methyl acrylate, ethyl acrylate, n-butyl acrylate, 2-methoxyethyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, benzyl acrylate, and the like, and from an industrial viewpoint, ethyl acrylate and n-butyl acrylate are preferred. The styrene monomer unit (g2-1) constituting the graft copolymer (shell portion) of the core-shell type rubbery polymer particle (G) is not particularly limited, and 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. The (meth)acrylic acid ester monomer unit (g2-2) constituting the graft copolymer (shell portion) of the core-shell type rubber-like polymer particle (G) includes a methacrylic acid ester monomer unit and an acrylic acid ester monomer unit. In addition, examples of the (meth)acrylic acid ester monomer unit 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, and methyl methacrylate are preferred from the viewpoint of industrial availability and low cost.

[0081] The content of the conjugated diene monomer (g1-1) or (meth)acrylic acid ester monomer unit (g1-2) constituting the rubber-like particles in the core-shell type rubber-like polymer particles (G) 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 rubber-like polymer particles (G). The higher the content of the monomer unit constituting the rubber-like particles, 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 monomer unit constituting the rubber-like particles is too high, the content of the graft copolymer containing the (meth)acrylic acid ester monomer unit (g2-2) 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.

[0082] The content of the styrene monomer unit (g2-1) in the graft copolymer of the core-shell type rubbery polymer particle (G) is 0 to 90 mass%, more preferably 0 to 70 mass%, and even more preferably 0 to 10 mass%. By making the content of the styrene monomer unit (g2) in the graft copolymer 10 mass% or less, the content of the methyl (meth)acrylate monomer unit (g2-2) contained in the graft chain increases, and compatibility with the matrix polymer portion constituting the styrene resin composition of this embodiment can be ensured, and the effect of improving the mechanical strength can be efficiently obtained. The matrix polymer portion essentially contains resin (A) and resin (B), and also contains one or more optional components selected from the group consisting of polymer matrix (C-1), polymer matrix (D-1), styrene-based elastomer (E), acrylic-based elastomer (F), monohydric alcohol having 10 or more carbon atoms, and optional added components. In other words, the matrix polymer portion refers to components other than the various rubber-like polymer particles and inorganic particles (H) contained in the styrene-based resin composition.

[0083] The content of the (meth)acrylic acid ester monomer unit (g2-2) in the graft copolymer of the core-shell type rubbery polymer particle (G) is 10 to 100 mass%, more preferably 30 to 96 mass%, and even more preferably 70 to 95 mass%. By making the content of the (meth)acrylic acid methyl monomer unit (g2-2) in the graft copolymer 70 mass% or more, it is possible to ensure compatibility with the matrix polymer portion constituting the styrene-based resin composition of this embodiment, and it is possible to efficiently obtain the effect of improving the mechanical strength.

[0084] The average particle size of the core-shell type rubbery polymer particles (G) is preferably 0.05 to 0.90 μm, more preferably 0.08 to 0.85 μm, even more preferably 0.10 to 0.75 μm, and even more preferably 0.15 to 0.70 μm. In particular, by setting the particle size in the range of 0.15 to 0.70 μm, the strength imparting effect of the styrene-based resin composition is excellent. Furthermore, in the present disclosure, the method for measuring the average particle size is a value measured from a cross-sectional observation image by a transmission electron microscope, as shown in the Examples section described later.

[0085] As a method for producing the core-shell type rubbery polymer particles (G), an emulsion polymerization method is preferred in which latex particles containing a rubber component (e.g., butadiene rubber latex and / or acrylic rubber latex) are produced and then copolymerized with styrene-based monomer units (g2-1) and / or (meth)acrylic acid ester monomer units (g2-2).

[0086] <Inorganic particles (H)> In a preferred embodiment of the present invention, the styrene-based resin composition preferably contains inorganic particles (H). By adding the inorganic particles (H) to the styrene-based resin composition, the inorganic particles (H) serve as a foam nucleating agent during foam molding and contribute to improving the rigidity of the molded article including the composition and the foam sheet.

[0087] Examples of inorganic particles (H) 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.

[0088] The content of the inorganic particles (H) 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.

[0089] There is no particular limitation on the method of adding the inorganic particles (H) to the styrene-based resin composition. The inorganic particles (H) may be directly blended with the styrene-based resin composition when the composition is extruded and kneaded. Alternatively, for ease of industrial production, a resin master batch containing the inorganic fine particles (H) at a known high concentration may be prepared in advance and then added to the composition.

[0090] <Monohydric alcohols with 10 or more carbon atoms> In the present embodiment, the monohydric alcohol having 10 or more carbon atoms (hereinafter, 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 and the molded article made of the styrene-based resin composition having a good appearance. The content of the monohydric alcohol having 10 or more carbon atoms is 0.01 to 1.0 mass%, preferably 0.03 to 0.8 mass%, more preferably 0.05 to 0.6 mass%, and even more preferably 0.07 to 0.5 mass%, based on the total amount (100 mass%) of the styrene-based resin composition. By making the content of the monohydric alcohol having 10 or more carbon atoms 0.01 mass% or more, it is possible to suppress gelation of the styrene-unsaturated carboxylic acid resin (A) during molding processing, and by making it 1.0 mass% or less, it is possible to suppress the decrease in heat resistance and the generation of odor. By making the content of the monohydric alcohol having 10 or more carbon atoms 0.07 to 0.5 mass%, a sufficient gel suppression effect can be obtained without particularly decreasing heat resistance.

[0091] The monohydric alcohol 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, amide bonds, etc. 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, by making a monohydric alcohol having 10 or more carbon atoms present (or added) in a polymerization solution used for polymerizing the styrene-unsaturated carboxylic acid-based resin (A) or the (meth)acrylic resin (B), the monohydric alcohol may remain 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.

[0092] In this embodiment, the boiling point of the monohydric alcohol 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.

[0093] The monohydric alcohol 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.

[0094] 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" manufactured by Kao Corporation.

[0095] "Optional added ingredients" In addition to the above-mentioned (A) to (H) components and the monohydric alcohol having 10 or more carbon atoms, the styrene-based resin composition of this embodiment can also be made into a styrene-based resin composition by blending various optional additive components generally used in styrene-based resins to achieve known effects. Examples of the optional additive components of this embodiment include additives such as stabilizers, higher fatty acid surfactants, antioxidants, ultraviolet absorbers, lubricants, release agents, plasticizers, antiblocking agents, antistatic agents, antifogging agents, and mineral oils. There are no particular restrictions 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 after polymerization and before melt-kneading, and then melt-kneading with an extruder or Banbury mixer, etc.

[0096] 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.

[0097] 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 polymerization of each resin, or may be additionally kneaded when the styrene-unsaturated carboxylic acid resin (A) and the (meth)acrylic resin (B) are kneaded together.

[0098] The higher fatty acid surfactant is not particularly limited, but examples thereof include stearic acid, calcium stearate, calcium stearate, ethylene bis stearamide, and the like, with ethylene bis stearamide being particularly preferred.

[0099] [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.

[0100] <Composition of styrene-based resin composition> 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. 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. The styrene-based resin composition of the present embodiment contains resin (A), resin (B), and resin (C), and the total content of resin (A), resin (B), and resin (C) is preferably 70 to 100 mass%, and more preferably 80 to 90 mass%, based on the entire styrene-based resin composition. The styrene-based resin composition of the present embodiment comprises resin (A), resin (B), resin (C), and any additive components, and the total content of resin (A), resin (B), resin (C), 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. The styrene-based resin composition of the present embodiment contains resin (A), resin (B), and resin (D), and the total content of resin (A), resin (B), and resin (D) is preferably 70 to 100 mass%, and more preferably 80 to 90 mass%, based on the entire styrene-based resin composition. The styrene-based resin composition of the present embodiment comprises resin (A), resin (B), resin (D), and any additive components, and the total content of resin (A), resin (B), resin (D), 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. The styrene-based resin composition of the present embodiment contains resin (A), resin (B), and elastomer (E), and the total content of resin (A), resin (B), and elastomer (E) is preferably 70 to 100 mass%, and more preferably 80 to 90 mass%, based on the entire styrene-based resin composition. The styrene-based resin composition of the present embodiment comprises resin (A), resin (B), elastomer (E), and any additive components, and the total content of resin (A), resin (B), elastomer (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. 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.

[0101] 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. The styrene-based resin composition of the present embodiment contains resin (A), resin (B), and core-shell particles (G), and the total content of resin (A), resin (B), and core-shell particles (G) is preferably 70 to 100 mass%, and more preferably 80 to 90 mass%, of the entire styrene-based resin composition. The styrene-based resin composition of the present embodiment comprises resin (A), resin (B), core-shell particles (G), and any additive components, and the total content of resin (A), resin (B), core-shell particles (G), and any additive components is preferably 85 to 100 mass%, and more preferably 90 to 95 mass%, of the entire styrene-based resin composition. The styrene-based resin composition of the present embodiment contains resin (A), resin (B) and inorganic particles (H), and the total content of resin (A), resin (B) and inorganic particles (G) is preferably 60 to 100 mass%, and more preferably 75 to 98 mass%, based on the entire styrene-based resin composition. The styrene-based resin composition of the present embodiment comprises resin (A), resin (B), inorganic particles (H), and any additive components, and the total content of resin (A), resin (B), inorganic particles (H), and any additive components is preferably 75 to 100 mass%, and more preferably 80 to 98 mass%, based on the entire styrene-based resin composition. The styrene-based resin composition of the present embodiment contains resin (A), resin (B), resin (D), and elastomer (E), and the total content of resin (A), resin (B), resin (D), and elastomer (E) is preferably 70 to 100 mass%, and more preferably 85 to 90 mass%, based on the entire styrene-based resin composition. The styrene-based resin composition of the present embodiment is composed of resin (A), resin (B), resin (D) and elastomer. The styrene-based resin composition preferably contains the resin (A), the resin (B), the resin (D), the elastomer (E) and any additional components, and the total content of the resin (A), the resin (B), the resin (D), the elastomer (E) and any additional components may be 85 to 100 mass%, more preferably 90 to 95 mass%, based on the entire styrene-based resin composition. The styrene-based resin composition of the present embodiment comprises resin (A), resin (B), resin (C) and elastomer (F), and the total content of resin (A), resin (B), resin (C) and elastomer (F) is preferably 70 to 100 mass%, more preferably 85 to 90 mass%, based on the entire styrene-based resin composition. The styrene-based resin composition of the present embodiment comprises resin (A), resin (B), resin (C), elastomer (F), and any additive components, and the total content of resin (A), resin (B), resin (C), 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.

[0102] The styrene-based resin composition of the present embodiment contains resin (A), resin (B), resin (D), and elastomer (F), and the total content of resin (A), resin (B), resin (D), and elastomer (F) is preferably 70 to 100 mass%, and more preferably 85 to 90 mass%, based on the entire styrene-based resin composition. The styrene-based resin composition of the present embodiment comprises resin (A), resin (B), resin (D), elastomer (F) and any additive components, and the total content of resin (A), resin (B), resin (D), 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.

[0103] The styrene-based resin composition of the present embodiment comprises resin (A), resin (B), elastomer (E), and core-shell particles (G), and the total content of resin (A), resin (B), elastomer (E), and core-shell particles (G) is preferably 70 to 100 mass%, and more preferably 85 to 90 mass%, of the entire styrene-based resin composition. The styrene-based resin composition of the present embodiment comprises resin (A), resin (B), elastomer (E), core-shell particles (G), and any additive components, and the total content of resin (A), resin (B), elastomer (E), core-shell particles (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.

[0104] The styrene-based resin composition of the present embodiment comprises resin (A), resin (B), elastomer (F), and core-shell particles (G), and the total content of resin (A), resin (B), elastomer (F), and core-shell particles (G) is preferably 70 to 100 mass%, and more preferably 85 to 90 mass%, of the entire styrene-based resin composition. The styrene-based resin composition of the present embodiment comprises resin (A), resin (B), elastomer (F), core-shell particles (G), and any additive components, and the total content of resin (A), resin (B), elastomer (F), core-shell particles (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.

[0105] <First molecular weight component of 10,000 or less> The styrene-based resin composition of the present embodiment contains the resin (A) and the resin (B), and may contain, as necessary, one or more selected from the group consisting of a (meth)acrylonitrile-diene-styrene-based resin (C), an impact-resistant styrene-based resin (D), a styrene-based elastomer (E), an acrylic elastomer (F), core-shell particles (G), inorganic particles (H), a monohydric alcohol having 10 or more carbon atoms, and an optional additive component. The styrene-based resin composition of the present embodiment essentially contains the resin (A) and the resin (B), and has a matrix polymer portion (so-called a continuous phase of a polymer) containing one or more optional components selected from the group consisting of a polymer matrix (C1), a polymer matrix (D1), a styrene-based elastomer (E), an acrylic elastomer (F), a monohydric alcohol having 10 or more carbon atoms, and an optional additive component. In the matrix polymer portion of the present embodiment, when the matrix polymer portion is divided into a molecular weight component (=first molecular weight component) having a molecular weight of 10,000 or less and a molecular weight component (=second molecular weight component) having a molecular weight of more than 10,000, the first molecular weight component having a molecular weight of 10,000 or less is preferably in the range of 0.5 to 3.0 mass% with respect to the total amount of the styrene-based resin composition. More preferably, it is in the range of 0.7 to 2.6 mass%, further preferably 0.9 to 2.5 mass%, and most preferably 1.0 to 2.1 mass%. If the amount of the first molecular weight component having a molecular weight of 10,000 or less is less than 0.5 mass%, the extensional viscosity of the molten resin increases and the moldability decreases. On the other hand, if the amount of the first molecular weight component having a molecular weight of 10,000 or less exceeds 3.0 mass%, the mechanical strength of the molded product decreases due to the excessive presence of low molecular weight components. By setting the amount of the first molecular weight component having a molecular weight of 10,000 or less to 0.5 to 3.0 mass%, a styrene-based resin composition that gives a foamed extruded sheet superior in both mechanical strength and moldability can be obtained. The amount of the first molecular weight component having a molecular weight of 10,000 or less was determined by using gel permeation chromatography (GPC) to measure the molecular weight in terms of standard polystyrene using a calibration curve method using standard polystyrene, and calculating the proportion of components having a molecular weight of 10,000 or less in the entire composition from the molecular weight distribution obtained.

[0106] <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 112° C. or higher. By setting the Vicat softening temperature at 105° C. or higher, a sheet or container that can be applied to cooking in a general microwave oven of about 500 W can be obtained, and by setting the Vicat softening temperature at 112° C. or higher, it can withstand cooking in a high-power commercial microwave oven of 1000 W or higher that is installed in a convenience store, etc. The Vicat softening temperature can be measured in accordance with ISO306 under conditions of a load of 50 N and a heating rate of 50° C. / h.

[0107] <Content of conjugated diene monomer units> In this embodiment, the content of the conjugated diene monomer unit contained in the styrene resin composition is preferably 0 to 10 mass %, more preferably 0.3 to 5.0 mass %, even more preferably 0.5 to 4.8 mass %, and most preferably in the range of 0.6 to 4.0 mass %, based on the entire styrene resin composition. 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 product, sheet, or container obtained by molding the composition. As described above, the conjugated diene monomer unit is a general term for the conjugated diene monomer (c2), the conjugated diene monomer (d2) and the conjugated diene monomer (e2).

[0108] <(Meth)acrylic acid monomer or (meth)acrylic acid ester monomer 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%, more preferably 3 to 15 mass%, more preferably 4 to 13 mass%, even more preferably 5 to 10 mass%, and most preferably 6 to 8 mass%, based on the total amount (100 mass%) of the styrene-based resin composition. 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. The total (meth)acrylic acid monomer content refers to the total amount of all (meth)acrylic acid monomer units present in the styrene-based resin composition, and therefore includes resin (A), resin (B) and the like. The contents of the (meth)acrylic acid monomer units in the other components (resin (C), resin (D), elastomer (F), core-shell particles (G) and any added components) are also converted.

[0109] 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 52 mass%, more preferably 17 to 47 mass%, and most preferably 25. 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. 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 the (meth)acrylic acid ester monomer units in the resin (A), the resin (B) and other components (the resin (C), the rubber-like polymer particles (D), the resin (E), the elastomer (G), the core-shell particles (G) and any added components).

[0110] 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 (meth)acrylic acid monomer units can provide an improved heat resistance, and as a result, a styrene-based resin composition having excellent heat resistance and a foamed sheet and a container molded from the same can be obtained.

[0111] <Content of styrene-based component in styrene-based resin composition> The styrene-based resin composition in this embodiment contains a styrene-based component. The styrene-based component here refers to a collective term for the styrene-based monomer (unit) (a1) and the styrene-based monomer (unit) that may be contained in other components (resin (B), resin (C), rubber-like polymer particles (D), resin (E), elastomer (F), core-shell particles (G), and any added components). In the styrene-based resin composition of the present embodiment, the content of the styrene-based components (total styrene-based monomers (units)) relative to the total amount (100 mass%) of the styrene-based resin composition is preferably 45 to 85 mass%, more preferably 55 to 83 mass%, and further preferably 58 to 80 mass%. When the content is in the range of 45 to 85, a styrene-based resin composition having an excellent balance between moldability and heat resistance can be obtained.

[0112] In a preferred embodiment of the styrene-based resin composition in this embodiment, the content of the styrene-based monomer unit is 45 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 72 mass%, the content of the (meth)acrylic acid monomer unit is 5 to 10 mass%, the content of the (meth)acrylic acid ester monomer unit is 17 to 50 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.

[0113] 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. The total amount of all rubber-like polymer particles (including encapsulated resin) in the entire styrene-based resin composition of the present embodiment is preferably 0.5 to 8.0 mass%, more preferably 0.6 to 6.5 mass%, even more preferably 0.7 to 5.5 mass%, and even more preferably 0.8 to 4.5 mass%, relative to the total amount (100 mass%) of the styrene-based resin composition. I wish. 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. In addition, when each of the rubber-like polymer particles, i.e., the ABS rubber-like polymer particles (C2) and the rubber-like polymer particles (D2), contains components (polymer domain phase) other than the conjugated diene monomer units, the components (polymer domain phase) other than the conjugated diene monomer units are also included in the content of all the rubber-like polymer particles. The content of the conjugated diene monomer (=rubber amount) in all rubber-like polymer particles in the entire styrene-based resin composition of this embodiment is preferably 0 to 10 mass%, more preferably 0.3 to 5.0 mass%, even more preferably 0.5 to 4.8 mass%, and most preferably 0.6 to 4.0 mass%, relative to the total amount (100 mass%) of the styrene-based resin composition. It is possible to obtain a styrene-based resin composition having an excellent balance between strength and rigidity, and a molded body, sheet, and container obtained by molding the composition. The total rubber-like polymer particles include the rubber-like polymer particles (C2) and the rubber-like polymer particles (D2).

[0114] [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.

[0115] <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.

[0116] 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.

[0117] In this embodiment, when a foamed extruded sheet is formed, 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 (H) above, 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 within 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 resin pellets in which a high concentration of the foam nucleating agent has been dispersed by extrusion kneading are added. good.

[0118] 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.

[0119] 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 / cm 3 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.

[0120] 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.

[0121] 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.

[0122] 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.

[0123] 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.

[0124] 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. 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.

[0125] [Secondary molded product] The 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 forming and compressed air forming. Such a thermoforming method is a preferred method because 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. EXAMPLES

[0126] 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 and extruded sheets in the examples and comparative examples were analyzed and evaluated as follows.

[0127] [Composition evaluation of each resin and resin composition] (1) Measurement of the content of each monomer unit 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: Each resin, and the resin compositions prepared in the Examples and Comparative Examples were dissolved in chloroform at 5% by mass, and 20 μL was dropped into a sample cup and dried in vacuum at 80° C. for 24 hours. Measurement conditions Pyrolysis Unit Equipment: Frontier Labs PY-3030D Furnace temperature: 600℃ GC Equipment: Shimadzu GCMS-GP2020NX Column: Ultra Alloy-CW (Length 30m, film thickness 0.25μm, diameter 0.25mmφ) Column temperature: held at 40°C for 3 minutes, heated at 10°C / min, and held at 250°C for 10 minutes. Inlet temperature: 250℃ Detector temperature: 230℃ Split ratio: 1 / 300 Carrier gas: Helium Detection method: Mass spectrometer (MSD) In detecting each monomer peak, in order to avoid peak overlap or saturation of peak intensity, pretreatment such as dilution rate of the sample, the column to be used, and detection conditions may be appropriately adjusted. (2) Measurement of the content of monohydric alcohols having 10 or more carbon atoms in each resin composition The content of monohydric alcohol having 10 or more carbon atoms in the entire resin composition prepared in each of 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 6850 series GC system Detector: FID Column: DB-WAX Length: 60m Film thickness: 0.50μm Diameter: 0.320mmφ Injection volume: 1μL Split ratio: 50:1 Column temperature: Hold at 100°C for 5 minutes → Raise to 130°C at 10°C / min → Raise to 180°C at 10°C / min → Hold at 180°C for 10 minutes → Raise to 220°C at 20°C / min → Hold at 220°C for 10 minutes Inlet temperature: 230℃ Detector temperature: 300℃ Carrier gas: Helium In addition, when detecting the peak of monohydric alcohol (C) with 10 or more carbon atoms, In order to avoid overlapping and saturation of peak intensity, pretreatment such as dilution rate of the sample, the column to be used, and detection conditions may be appropriately adjusted. [Evaluation of properties of each resin and resin composition] (3) Measurement of the amount of first molecular weight components of 10,000 or less The ratio of the first molecular weight component of 10,000 or less in each of the resins and resin compositions produced in the examples and comparative examples was measured as a standard polystyrene-equivalent molecular weight using gel permeation chromatography (GPC) under the following conditions by 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: 5 mg of the measurement sample was dissolved in 10 mL of solvent and filtered through a 0.45 μm filter. Injection volume: 10μL Measurement temperature: 40℃ Flow rate: 0.35mL / min Detector: Differential refractometer The calibration curve was created using 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 Corporation. The calibration curve was created using a linear approximation equation.

[0128] (4) 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, 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 115°C in particular tended to show almost no dimensional change at practical temperatures.

[0129] (5) Melt tension measurement The melt tension (gf) of each of the resins and resin compositions produced in the Examples and Comparative Examples was measured under the following conditions. Measurement equipment: Malvern Capillary Rheometer RH10 Capillary die: 2mmφ×20mmL Measurement temperature: 220℃ Piston drop speed: 8.1mm / min Winding speed: 3.1m / min Drying conditions: Each resin and resin composition was dried at 80° C. for 2 hours before measurement. After drying the styrene-based resin composition of the example and the resin composition obtained in the comparative example at 80°C for 2 hours or more, about 30 g of each was put into a cylinder, and the piston was lowered at 8.1 mm / min. Six minutes after the sample was put in, the strand coming out of the die was attached to a pulley and a winding drum, and winding was started at 3.0 m / min. Ten minutes after the sample was put in, the winding speed was increased to 3.1 m / min, and melt tension measurement was started. The melt tension value was measured 100 times in 5 minutes, and the average value was taken as the melt tension (MT) measurement value.

[0130] (6) Measurement of extensional viscosity The extensional viscosity (EV) of each of the resins and styrene-based resin compositions produced in the Examples and Comparative Examples was measured based on the following viscoelasticity measurement. Device name: TA Instruments viscoelasticity measuring device ARES-G2 Measurement system: ARES-EVF option Test piece dimensions: length 20mm, width 10mm, thickness 0.8mm Elongation strain rate: 1.0 / s Measurement temperature: 160℃ Measurement atmosphere: Nitrogen gas flow Preheat time: 2 minutes Pre-stretch strain rate: 0.03 / s Pre-extension length: 0.295mm Relaxation time after pre-stretch: 2 minutes The styrene-based resin compositions of the examples and the resin compositions produced in the comparative examples were dried at 80°C for 2 hours or more, and then 0.7 mm thick test pieces were molded using a 50-ton compression molding machine (hereinafter referred to as a compression molding machine) manufactured by Soken Co., Ltd. The molded test pieces were stored in a desiccator until measurement to prevent moisture absorption. The test pieces were attached to rollers with a stopper distance of 18 mm, and after the temperature stabilized at the measurement temperature, they were left to stand for 2 minutes for preheating. After preheating, preliminary extension was performed under the above conditions, and then the test pieces were left to stand for 2 minutes to relax the stress generated by the preliminary extension, and the extensional viscosity was measured. The measured value when the Hencky strain was 0.5 was taken as the extensional viscosity (EV) measurement value.

[0131] (7) Evaluation of surface impact of solid sheet The styrene resin compositions of the examples and the resin compositions of the comparative examples were dried at 80°C for 2 hours or more, and then a solid sheet of 0.7 mm thick was made using a compression molding machine. After cutting into a size of 8 x 8 cm, the film impact was measured using a film impact tester (No. 195) manufactured by Toyo Seiki Co., Ltd., and the n8 average was used as the value.

[0132] (8) Evaluation of deep drawing formability of non-foamed sheets The styrene-based resin composition of the embodiment and each resin composition produced in the comparative example were dried at 80°C for 2 hours or more, and then a solid sheet of 0.7 mm thick was produced using a compression molding machine. A test piece of 250 mm long x 250 mm wide was cut out from the obtained sheet, and the test piece was sandwiched between the fixed frame of a sheet container molding machine manufactured by Soken Co., Ltd., and heated for 20 seconds with the average heater temperature set to 230°C and the atmospheric temperature set to 120°C. Next, the fixed frame was slid into a bowl container mold (temperature 40°C) with a diameter of 10 cm and a depth of 6 cm, and vacuum molding was performed, forming 20 molded bodies at a time. The side of this molded body was visually checked for tears, and the number of molded bodies that could be molded without tears was used as an index of deep drawing moldability.

[0133] [Evaluation of properties of foam extrusion sheets] (9) Basis weight of foam extrusion sheet (g / m 2 ) From the foamed extruded sheets produced in the Examples and Comparative Examples, 20 mm from both ends were removed to prepare sheet pieces of 0.10 × 0.10 m. The mass of each piece was measured, and the thickness was reduced to 1.0 m. 2 The mass converted to basis weight (g / m 2 ) was calculated.

[0134] (10) Closed cell ratio of foamed extruded sheet The closed cell ratio of the foamed extruded sheet was measured in accordance with JIS K7138.

[0135] (11) Measurement of heat resistance of foam extrusion sheet 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 (I), and the n5 average was taken as the value. Formula (I): 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 ◎: No change in dimensions ○: Dimensional change is 1% or less △: Dimensional change between 1% and 3% ×: Dimensional deformation 3% or more

[0136] (12) Evaluation of deep drawing formability of foam sheet A test piece measuring 250 mm long x 250 mm wide was cut out from the foamed extrusion sheet produced in the examples and comparative examples, and left at 23±3°C and 50±5% relative humidity for 20 days. Then, using a sheet container molding machine manufactured by Soken, the foamed sheet was sandwiched between the fixed frame of the sheet molding machine, the average temperature of the heater was set to 230°C, the atmospheric temperature was set to 160°C, and the sheet was heated for 15 seconds. Next, the fixed frame was slid into a cup-shaped mold (temperature 40°C) with a diameter of 10 cm and a depth of 3 cm or 6 cm, and vacuum molding was performed, forming 100 molded bodies each. The side of the molded body was visually checked for tears, and the number of molded bodies that could be molded without tears was used as an index of deep drawing formability.

[0137] [Evaluation of the properties of products obtained by secondary molding of foamed extrusion sheets] 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, and were subjected to the evaluations described in the following (13) and (14).

[0138] (13) Impact strength of foam containers A test piece measuring 80 mm in length and 80 mm in width was cut out from the center of the bottom of the foam container, and the film impact was measured using a Toyo Seiki film impact tester (No. 195) in a direction in which an impact was applied to the outer part of the container. The n8 average value was used as the value, and the film impact was evaluated from the following perspectives. ◎: 4.0kg or more 〇: 2.0kg·cm or more ~ ​​4.0kg·cm or less ×: Less than 2.0kg cm With containers with a load of less than 2.0 kgf, the transport container was prone to cracking.

[0139] (14) Appearance of foam container The surface condition of the foamed container was visually observed. Molded products that had no unevenness or roughness on the surface were judged to have a good appearance, and the number of molded products with a good appearance out of 100 molded products was used as an index for evaluation.

[0140] [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 styrene-unsaturated carboxylic acid resin (A-1)- 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 230°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 (A-1) obtained by the above-mentioned analytical methods are shown in Table 1 below.

[0141] -Preparation of styrene-unsaturated carboxylic acid resin (A-2)- Resin (A-2) was prepared in the same manner as for the preparation of Resin (A-1) under the polymerization conditions for the preparation of Resin (A-1) using the feed amounts of each monomer shown in Table 1. The composition and physical properties of the obtained Resin (A-2) are shown in Table 1.

[0142] -Preparation of styrene-unsaturated carboxylic acid resin (A-3)- Using only styrene as a monomer, a styrene homopolymer resin (A-3) having the composition and physical properties shown in Table 1 was obtained in the same manner as above.

[0143] [Table 1]

[0144] <Production Example of (Meth)acrylic Resin (B)> -Preparation of (meth)acrylic resin (B-1)- A 5L container equipped with an agitator was charged with 2 kg of water, 65 g of tribasic calcium phosphate, 39 g of calcium carbonate, and 0.39 g of sodium lauryl sulfate, and the suspension was prepared by mixing and stirring them. Next, 26 kg of water was charged into a 60L reactor and heated 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, 0.22 kg of methyl acrylate, 0.99 g of lauroyl peroxide, 4.93 g of n-octyl mercaptan, and the above suspension were charged as polymerization raw materials. Thereafter, 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. Subsequently, the mixture was cooled to 50°C, and 20% by mass of sulfuric acid was charged to dissolve the suspension. The polymerization reaction solution was then removed from the 60 L reactor, sieved through a 1.7 mm mesh sieve to remove large aggregates, and the aqueous layer and solids 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 a pellet-like resin (meth)acrylic resin (B-1) (hereinafter referred to as resin (B-1). The same applies to the other (meth)acrylic resins (B-2) and (B-3)).

[0145] -Preparation of (meth)acrylic resins (B-2), (B-3) and (B-5)- (Meth)acrylic resins (B-2), (B-3) and (B-5) were prepared in the same manner as for the preparation of resin (B-1) under the polymerization conditions in the preparation of resin (B-1) using the feed amounts of each monomer shown in Table 2. The compositions and physical properties of the obtained resins (B-2), (B-3) and (B-5) are shown in Table 2.

[0146] -Preparation of (meth)acrylic resin (B-4)- Ethylene, methyl methacrylate, and t-butyl-peroxy-2-ethylhexanoate, a polymerization initiator, were fed into a tubular reactor, and then continuously fed into a devolatilizer connected to a single-screw extruder for removing volatile components such as unreacted monomers and polymerization solvents. The gas concentration of methyl methacrylate in the feed gas was 5.5% by mass. The polymerization temperature in the tubular reactor was 220°C. The temperature of the single-screw extruder was set to 150-170°C, and the pressure was set to 10 torr, to devolatilize volatile components such as unreacted monomers and polymerization solvents. The resin was pelletized. The physical properties of the resin (B-4) obtained by the above-mentioned analytical methods are shown in Table 2 below.

[0147] -Preparation of (meth)acrylic resin (B-6)- In this example, ARUFON UP-1021 manufactured by Toagosei Co., Ltd. was used as the resin (B-6).

[0148] -Preparation of (meth)acrylic resin (B-7)- In this example, Acryft WH206-F manufactured by Sumitomo Chemical was used as the resin (B-7).

[0149] [Table 2]

[0150] In order to confirm the characteristics of the (meth)acrylic resin (B), the number of inflection points was measured for the resins (B-1) and (B-2) as an example. Specifically, the inflection points were determined as points where the second derivative of the differential molecular weight distribution curve obtained from the GPC measurement was 0, and the number of inflection points was counted. The differential molecular weight distribution curve of the resin (B-1) had two inflection points, and the differential molecular weight distribution curve of the resin (B-2) had four inflection points.

[0151] <Production Example of (Meth)acrylonitrile-Diene-Styrene Resin (C)> The outline of the preparation method of the (meth)acrylonitrile-diene-styrene resin (C) used in this embodiment is to first prepare a resin (C2-1) containing butadiene-styrene-acrylonitrile graft copolymer particles (rubber-like polymer particles (C2)) at a high concentration, then knead and dilute the separately prepared styrene-acrylonitrile copolymer (C1-1) and the resin (C2-1) containing the butadiene-styrene-acrylonitrile graft copolymer particles at a high concentration, and adjust the concentration of the rubber-like polymer particles (C2) and the polymer matrix (C1) to a desired value. Below, a specific example of the preparation method will be described.

[0152] -Preparation of (meth)acrylonitrile-diene-styrene resin (hereinafter, ABS resin) (C-1)- 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. 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 (C1-1) and butadiene-styrene-acrylonitrile graft copolymer (C2-1) obtained in this way. 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 aluminum sulfate aqueous 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 (C2-1) containing a high concentration of butadiene-styrene-acrylonitrile graft copolymer particles (C2-1). As a result of composition analysis, the composition ratio of the above resin (C2-1) 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 (C1-1). The composition of the copolymer (C1-1) 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). The butadiene-styrene-acrylonitrile graft copolymer particles (rubber-like polymer particles (C2)) obtained by the above procedure were mixed with a resin (C2-1) containing a high concentration of styrene-acrylonitrile graft copolymer particles (rubber-like polymer particles (C2)). The nitrile copolymer (C1-1) was extrusion-kneaded and pelletized using a twin-screw extruder to obtain ABS resin (C-1) in the form of pellets.

[0153] -Preparation of ABS resin (C-2)- The feed amount of each monomer and the polymerization conditions were adjusted to prepare resin (C2-1) in the same manner as the above ABS resin (C-1), 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 (C-2) as a pellet-shaped ABS compound resin. The composition and physical properties of the obtained ABS resin (C-2) are shown in Table 3.

[0154] [Table 3]

[0155] <Production example of impact resistant styrene resin (D)> -Preparation of impact-resistant styrene resin (D-1)- 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 was used to produce impact-resistant styrene resin (D-1) (hereinafter referred to as resin (D-1)). 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 (D2), 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 performed 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 (D2) 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 impact-resistant styrene-based resin (D-1) (hereinafter referred to as resin (D-1). The same applies to other impact-resistant styrene-based resins (D-2) and (D-3)) are shown in Table 4.

[0156] -Preparation of impact resistant styrene resins (D-2) and (D-3)- Resin (D-2) and resin (D-3) having the composition and physical properties shown in Table 4 were 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 (D2).

[0157] -Preparation of impact-resistant styrene resin (D-4)- Resin (D-4) having the composition and physical properties shown in Table 4 was obtained in the same manner as above using styrene and methyl methacrylate as monomers and high cis butadiene rubber 15HB manufactured by Ube Industries as the rubber-like polymer (D2).

[0158] [Table 4]

[0159] <Styrene-based elastomer (E) used in the examples> In the examples of this specification, the styrene-butadiene block copolymer Tufprene 125 (=styrene-based elastomer (E-1)) manufactured by Asahi Kasei Corp. was used as the styrene-based elastomer (E). Table 5 shows the properties.

[0160] [Table 5]

[0161] <Acrylic elastomer (F) used in the examples> In the examples of this specification, the following three types of acrylic elastomer (F) were used. Resin (F-1): Kuraray Clarity LA4285 Resin (F-2): Kuraray Clarity LA2270 Resin (F-3): Kuraray Clarity LA2250 All of the above acrylic elastomers (F) are poly(methyl methacrylate-b-(n-butyl)acrylate-b-methyl methacrylate) triblock copolymers, and have the properties shown in Table 6 below.

[0162] [Table 6]

[0163] <Production Example of Core-Shell Type Rubber Polymer Particles (G)> -Preparation of rubber-like polymer particles (G-1)- 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. Next, while maintaining the rubber latex obtained above (solid content about 71 parts) at 60 ° C, styrene and methyl methacrylate 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, and dried by dehydration to obtain rubber-like polymer particles (G-1) as powder. The composition and physical properties of the rubber-like polymer particles (G-1) are shown in Table 7.

[0164] -Preparation of rubber-like polymer particles (G-2) and (G-3)- Using methyl methacrylate and n-butyl acrylate as graft chain monomers, (G-2) and (G-3) were prepared in the same manner as (G-1) above. The compositions and physical properties of the resulting rubber-like polymer particles (G-2) and (G-3) are shown in Table 7.

[0165] -Preparation of rubber-like polymer particles (G-4)- (G-4) was prepared in the same manner as (G-1) above, except that n-butyl acrylate was used as the rubber latex monomer. The composition and physical properties of the resulting rubber-like polymer particles (G-4) are shown in Table 7.

[0166] -Preparation of rubber-like polymer particles (G-5)- In this example, the resin (G-5) used was Metablen W-450A manufactured by Mitsubishi Chemical Corporation.

[0167] [Table 7]

[0168] <Monohydric alcohols having 10 or more carbon atoms used in the examples> In the examples of this specification, the following alcohol species were used as monohydric alcohols having 10 or more carbon atoms. Nissan Chemical Fine Oxocol 180 (5,7,7-trimethyl-2-(1,3,3-trimethylbutyl)-1-octanol) was used. Emulgen 109P (polyoxyethylene (9) lauryl ether monoalcohol) manufactured by Kao Corporation was used.

[0169] <<Production Examples of Styrene-Based Resin Compositions and Foam Extrusion Sheets>> The detailed production method of the styrene resin composition and the foamed extruded sheet will be described below. [Example 1] -Production of styrene-based resin composition- 93.0 parts by mass of resin (A-1) shown in Table 1 as styrene-unsaturated carboxylic acid resin (A), 7.0 parts by mass of resin (B-1) shown in Table 2 as (meth)acrylic resin (B), and 0.12 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 8-1. - 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 (High Filler #12 manufactured by Matsumura Sangyo Co., Ltd.) as inorganic fine particles (H) 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 the cylindrical foam was cut open 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 8-1.

[0170] [Examples 2 to 36] Except for changing the formulation as shown in Tables 8-1 to 8-4 below, styrene-based resin compositions [2] to

[36] and foamed extruded sheets [2] to

[36] were obtained in the same manner as in Example 1. The evaluation results of the obtained styrene-based resin compositions [2] to

[36] and foamed extruded sheets [2] to

[36] and the evaluation results of the foamed containers obtained by secondary molding of the foamed extruded sheets are shown in Tables 8-1 to 8-4.

[0171] [Table 8-1]

[0172] [Table 8-2]

[0173] [Table 8-3]

[0174] [Table 8-4]

[0175] [Comparative Examples 1 to 3] Resin compositions and biaxially stretched sheets were obtained in the same manner as in Example 1, except that the mixing ratio was changed as shown in Table 9. Table 9 shows the evaluation results of the obtained resin compositions and foamed sheets, and the evaluation results of the foamed containers obtained by secondary molding of the foamed sheets.

[0176] [Table 9] [Industrial Applicability]

[0177] The styrene-based resin composition obtained by the present invention is excellent in heat resistance, transparency, rigidity, heat oil resistance and appearance. 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), etc., and is particularly useful as a packaging material compatible with microwave cooking, and plays a major role in the industrial world.

Claims

1. 50 to 98% by mass of a styrene-unsaturated carboxylic acid resin (A) having a styrene monomer unit (a1) and an unsaturated carboxylic acid monomer unit (a2); More than 0 to 50 mass% of a (meth)acrylic resin (B) containing an unsaturated carboxylic acid monomer unit (b1); A styrene-based resin composition comprising more than 1% by mass and not more than 25% by mass of core-shell type rubbery polymer particles (G), The core-shell type rubbery polymer particles (G) have a rubbery particle as a core portion and a graft copolymer as a shell portion that at least partially covers the core portion, The unsaturated carboxylic acid monomer unit (a2) is one or more selected from the group consisting of (meth)acrylic acid monomer units (a2-1) and (meth)acrylic acid ester monomer units (a2-2), The content of the styrene-based monomer unit (a1) is 84.0 to 92.0% by mass based on the styrene-unsaturated carboxylic acid-based resin (A), the (meth)acrylic resin (B) is a binary or ternary copolymer containing, as the unsaturated carboxylic acid monomer unit (b1), at least one of a (meth)acrylic acid monomer unit (b1-1) or a (meth)acrylic acid ester monomer unit (b1-2), and containing a total of two or three types of monomer units selected from the group consisting of the (meth)acrylic acid monomer unit (b1-1), the (meth)acrylic acid ester monomer unit (b1-2), and an olefin monomer unit, the (meth)acrylic acid ester monomer unit (b1-2) is methyl acrylate, ethyl 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, or benzyl methacrylate; the total content of the styrene-unsaturated carboxylic acid resin (A), the (meth)acrylic resin (B), and the core-shell type rubber polymer particles (G) accounts for 80 to 100% by mass based on the entire styrene-based resin composition; The styrene-based resin composition has an elongational viscosity (MPa·s) of 0.6 MPa·s or less at a temperature of 160°C, a strain rate of 1.0 / s, and a Hencky strain of 0.

5.

2. The (meth)acrylic resin (B) contains an ethylene monomer as the olefin monomer unit. The styrene-based resin composition according to claim 1 , having a monomer unit.

3. 3. The styrene-based resin composition according to claim 1 or 2, wherein a value obtained by dividing a melt tension (gf) of the styrene-based resin composition at a temperature of 220° C. and a take-up speed of 3.1 m / min by an extensional viscosity (MPa s) of the styrene-based resin composition at a temperature of 160° C., a strain rate of 1.0 / s, and a Hencky strain of 0.5 is 16 or more.

4. The styrene-based resin composition according to claim 1, wherein the content of the (meth)acrylic resin (B) is 10 to 50 mass%.

5. The styrene-unsaturated carboxylic acid resin (A) contains, as essential components, the styrene monomer unit (a1), the (meth)acrylic acid monomer unit (a2-1), and the (meth)acrylic acid ester monomer unit (a2-2), The styrene-based resin composition according to claim 4, wherein the (meth)acrylic acid monomer unit (a2-1) is contained in an amount of 2 to 30 mass% and the (meth)acrylic acid ester monomer unit (a2-2) is contained in an amount of 1 to 20 mass% based on the entire styrene-unsaturated carboxylic acid-based resin (A).

6. The styrene-based resin composition according to claim 4, wherein the content of all (meth)acrylic acid ester monomer units contained in the styrene-based resin composition is 10 to 50 mass% 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 (meth)acrylic resin (B) is a copolymer comprising methyl methacrylate monomer units and one or more types of monomer units other than methyl methacrylate, and contains 10 to 98 mass% of methyl methacrylate monomer units based on the total amount of the copolymer.

8. The resin composition according to claim 1 or 2, wherein the (meth)acrylic resin (B) has four or more inflection points in a differential molecular weight distribution curve.

9. 3. The styrene-based resin composition according to claim 1, wherein, when a matrix polymer portion of the styrene-based resin composition is divided into a first molecular weight component having a molecular weight of 10,000 or less and a second molecular weight component having a molecular weight of more than 10,000, the first molecular weight component having a molecular weight of 10,000 or less is 0.5 to 3.0 mass% with respect to a total amount of the styrene-based resin composition.

10. The inorganic particles (H) are added in an amount of 0.05 to 3.0% by mass based on the total amount of the styrene-based resin composition. The styrene-based resin composition according to claim 1 or 2,

11. A molded article having a closed cell ratio of 80% or more, which is obtained by molding the styrene-based resin composition according to claim 10. and the average thickness is in the range of 0.5 to 3 mm.

12. A foamed container obtained by secondary molding of the foamed extruded sheet according to claim 11.

Images