JP2023094450A - Styrene-based resin composition, extruded sheet, formed article, and food packaging container - Google Patents

Abstract

To provide a styrene-based resin composition, an extruded sheet, a formed article, and a food packaging container that have excellent heat resistance, high transparency, and excellent low-temperature impact resistance.SOLUTION: The present invention is directed to a styrene-based resin composition comprising a styrene-unsaturated carboxylate resin (A), a (meth)acrylic resin (B), and a rubber component (C), wherein the weight ratio represented by (the content of the styrene-unsaturated carboxylate resin (A))/(the content of the (meth)acrylic resin (B)) is in a range of 1.0 to 4.0, and the rubber component (C) is contained in an amount of 1 to 45 mass% based on the total amount (100 mass%) of the styrene-based resin composition.SELECTED DRAWING: None

Description

The present disclosure relates to a styrenic resin composition, and an extruded sheet, molded article, and food packaging container molded using the styrenic resin composition.

Styrene-unsaturated carboxylic acid resins, represented by styrene-methacrylic acid copolymer resins, are excellent in heat resistance, transparency, rigidity, and appearance, and are inexpensive. It is widely used for foamed boards for housing insulation, diffusion plates for liquid crystal televisions containing diffusion agents, and so on. In particular, due to the recent spread of high-power microwave ovens used for commercial purposes such as convenience stores, the materials used for containers that can withstand cooking temperatures in high-power microwave ovens and lids that seal or cover the containers include: A styrene-unsaturated carboxylic acid resin is used.

For example, Patent Document 1 discloses a technique related to a masterbatch capable of easily producing a heat-resistant styrene-based copolymer foam sheet. Specifically, a heat-resistant styrene-based copolymer and a rubber A kneaded product of a polymer and a copolymer containing acrylate monomer units is described. Further, according to the masterbatch of Patent Document 1, it is described that even if the cell diameter of the foamed sheet is reduced, a heat-resistant styrene-based copolymer foamed sheet exhibiting excellent heat softening elongation can be produced. there is

Further, Patent Document 2 discloses a technique related to a styrene resin composition used in a packaging container for heating by a microwave oven. Specifically, a styrene-methacrylic acid copolymer resin and a 10,000 to 15,000,000 high molecular weight acrylic resin and a styrenic resin composition containing an acrylic resin. Further, according to Patent Document 2, it is described that compatibility between a styrene-methacrylic acid copolymer resin and an acrylic resin is improved by using a high-molecular-weight acrylic resin.

JP-A-11-60747 Japanese Patent Application Laid-Open No. 2018-203838

The technique of Patent Document 1 above is a material design premised on the foam sheet application, so although the surface appearance, deep drawability and breaking elongation of the foam sheet are studied, No consideration is given to properties such as transparency or oil resistance that are required for other uses. Further, in the technique of Patent Document 2, various physical properties such as sheet physical properties, oil resistance, microwave oven heating resistance, and the like are studied. However, packaging containers for heating in a microwave oven are also required to have impact resistance at low temperatures because the containers themselves are frozen as the food contents are stored frozen. However, neither Patent Document 2 nor Patent Document 1 discusses impact resistance at low temperatures.

Therefore, the problem to be solved by the present invention is to provide a styrene-based resin composition, an extruded sheet, a molded article, and a food packaging container that are compatible with excellent heat resistance, high transparency, and excellent low-temperature impact resistance. .

As a result of intensive research in view of the above problems, the present inventors have found that predetermined amounts of styrene-unsaturated carboxylic acid resin (A), (meth)acrylic resin (B), and rubber component (C) The styrenic resin composition contained in the styrenic resin composition has excellent heat resistance and low-temperature impact resistance, and an extruded sheet, molded article, and food packaging container using the same have been successfully realized, and the present invention has been completed. rice field. That is, the present disclosure is as follows.

[1] The present disclosure contains a styrene-unsaturated carboxylic acid resin (A), a (meth)acrylic resin (B) and a rubber component (C),
(Content of the styrene-unsaturated carboxylic acid resin (A))/(Content of the (meth)acrylic resin (B)) is 1.0 to 4.0. is the range and
The styrenic resin composition contains 1 to 45% by mass of the rubber component (C) relative to the total amount (100 mass) of the styrenic resin composition.
Styrene-unsaturated carboxylic acid resin (A), (meth)acrylic resin (B) and rubber component (C),
(content of the styrene-unsaturated carboxylic acid resin (A))/(content of the (meth)acrylic resin (B)) is in the range of 1 to 4;
A styrenic resin composition containing 1 to 45% by mass of the rubber component (C) relative to the total amount (100% by mass) of the styrenic resin composition.

[2] In the present embodiment, the styrene-unsaturated carboxylic acid resin (A) comprises a styrene-based monomer unit (a1), a (meth)acrylic acid monomer unit (a2-1) and (meth) A copolymer (A-1) having an acrylic acid ester monomer unit (a2-2) is preferred.

[3] In the present embodiment, the styrene-unsaturated carboxylic acid-based resin (A) is preferably contained in an amount of 45 to 75% by mass with respect to the entire styrene resin composition.

[4] In the present embodiment, the (meth)acrylic resin (B) preferably has a weight average molecular weight (Mw) of 70,000 to 900,000.

[5] In the present embodiment, the Vicat softening temperature is preferably 105°C or higher.

[6] In the present embodiment, it is preferable to further contain 0.5 to 30% by mass of impact-resistant polystyrene (C-2) with respect to the total amount (100% by mass) of the styrene-based resin composition.

[7] In the present embodiment, the rubber component (C) is a (meth)acrylic-butadiene-styrene copolymer having styrene monomer units (c1), methyl methacrylate monomer units and butadiene units. It is preferably one or more selected from the group consisting of (C-1) and rubber-like graft particles (C-2-1) derived from impact-resistant polystyrene (C-2).

[8] In the present embodiment, the rubber component (C) is the (meth)acrylic-butadiene-styrene copolymer (C-1) and the rubber-like graft particles (C-2-1). preferable.

[9] In the present embodiment, a matrix mixture and the rubber component ( The difference in refractive index from C) is preferably in the range of 0 to 0.01.

[10] In the present embodiment, the refractive index of the rubber component (C) is preferably in the range of 1.530 to 1.550.

[11] In the present embodiment, the rubber component (C) is preferably crosslinked rubber particles.

[12] In the present embodiment, it is preferable that the rubber component (C) is contained in an amount of 5 to 35% by mass with respect to the total amount (100% by mass) of the styrene-based resin composition.

[13] In the present embodiment, the styrene-unsaturated carboxylic acid resin (A) comprises 40 to 97% by mass of styrene monomer units (a1), 2 to 30% by mass of methacrylic acid monomer units, and methacrylic acid A copolymer having 1 to 30% by mass of methyl acid monomer units is preferred.

[14] The present embodiment is a molded article obtained by molding the styrenic resin composition described in [1] to [13] above.

[15] The present embodiment is an extruded sheet comprising the styrenic resin composition described in [1] to [13] above.

[16] The present embodiment is a food packaging container for microwave ovens, which is obtained by processing the molded product of [14] above.

According to the present disclosure, it is possible to provide a styrene-based resin composition, an extruded sheet, a molded article, and a food packaging container that are excellent in heat resistance, transparency, and low-temperature impact resistance.

EMBODIMENT OF THE INVENTION Hereinafter, the form (henceforth "this embodiment") for implementing this invention is demonstrated in detail. It should be noted that the present invention is not limited to the following embodiments, and various modifications can be made within the scope of the gist of the present invention.
[Styrene resin composition]
The styrene resin composition (hereinafter sometimes simply referred to as a resin composition) in the present embodiment comprises a styrene-unsaturated carboxylic acid resin (A), a (meth)acrylic resin (B), and a rubber component. (C) and. Then, the weight ratio represented by (content of the styrene-unsaturated carboxylic acid resin (A))/(content of the (meth)acrylic resin (B)) is in the range of 1.0 to 4.0. is. More preferably 1.2 to 3.8, still more preferably 1.4 to 3.6, even more preferably 1.6 to 3.4, most preferably 1.7 to 3.2. Furthermore, the content of the rubber component (C) is 1 to 45% by mass with respect to the total amount (100% by mass) of the styrene-based resin composition.
This makes it possible to achieve both excellent heat resistance, transparency and low-temperature impact resistance. Each component will be described in detail below.

"Styrene-unsaturated carboxylic acid resin (A)"
The styrene-unsaturated carboxylic acid-based resin (A) in the present embodiment is a copolymer resin (hereinafter referred to as It is simply referred to as resin (A)). The resin (A) mainly contributes to improving the heat resistance of the styrenic resin composition as a whole. In addition, the styrene-unsaturated carboxylic acid-based resin (A), if necessary, further has monomer units other than the styrene-based monomer unit (a1) and the unsaturated carboxylic acid-based monomer unit (a2). may
The content of the styrene-unsaturated carboxylic acid resin (A) is preferably 45 to 75% by mass, preferably 47 to 70% by mass, based on the total amount (100% by mass) of the styrene resin composition. More preferably 49 to 65% by mass, still more preferably 51 to 60% by mass. When the content of the styrene-unsaturated carboxylic acid resin (A) is 45% by mass or more, a sufficient effect of imparting heat resistance can be obtained, and when it is 65% by mass or less, the (meth) acrylic resin (B), the effect of improving the strength by the rubber component (C) can be sufficiently obtained.

<Styrene-based monomer (a1)>
In the styrene-unsaturated carboxylic acid-based resin (A) of the present embodiment, the content of the styrene-based monomer units (a1) is 40 to the total amount of the styrene-unsaturated carboxylic acid-based resin (A). 97% by mass, preferably 50 to 95% by mass, more preferably 60 to 91% by mass, and even more preferably 72 to 89% by mass. If the content of the styrene-based monomer unit (a1) is less than 40% by mass, the fluidity is lowered, and if it is more than 97% by mass, the desired amount of the unsaturated carboxylic acid-based monomer unit (a2) described later is added. It becomes difficult to contain it, and the effect of improving the heat resistance by the unsaturated carboxylic acid-based monomer unit (a2) (particularly, the (meth)acrylic acid monomer unit (a2-1)) cannot be obtained sufficiently.
Further, in the styrene resin composition of the present embodiment, the styrene monomer unit (a1) preferably contains 40 to 65% by mass with respect to the total amount of the styrene resin composition, preferably 42 to 60% by mass, more preferably 44 to 55% by mass, and even more preferably 46 to 50% by mass. When the content of the styrene-based monomer (a1) in the entire composition is within the above range, fluidity can be ensured, and a styrene-based resin composition having excellent moldability can be obtained.

In the present embodiment, the styrenic monomer (a1) is not particularly limited, but examples include styrene, α-methylstyrene, β-methylstyrene, paramethylstyrene, orthomethylstyrene, metamethylstyrene, chlorostyrene, bromostyrene and the like. From an industrial point of view, styrene and α-methylstyrene are particularly preferred, and styrene is more preferred. As the styrene-based monomer (a1), these can be used alone or in combination of two or more.
The term "styrene-based monomer unit (a1)" used herein means a repeating unit that constitutes a polymer obtained by polymerizing the styrene-based monomer (a1), and the styrene-based monomer (a1 ) is a repeating unit (or structural unit) in which the carbon-carbon double bond in the styrenic monomer (a1) becomes a single bond (--C--C--) by the polymerization reaction or cross-linking reaction. In addition, other monomeric units in this specification have the same meaning.

<Unsaturated carboxylic acid-based monomer (a2)>
In the styrene-unsaturated carboxylic acid-based resin (A) of the present embodiment, the unsaturated carboxylic acid-based monomer unit (a2) has oil resistance and compatibility with the (meth)acrylic resin (B) described later. play a role in improving The content of the unsaturated carboxylic acid-based monomer unit (a2) is preferably 2 to 60% by mass, more preferably 3 to 50% by mass, based on the total amount of the styrene-unsaturated carboxylic acid-based resin (A). %, more preferably 5-40% by weight, most preferably 7-30% by weight. If the content of the unsaturated carboxylic acid-based monomer units (a2) is less than 2% by mass, the effect of improving the heat resistance is insufficient. In addition, when the content of the unsaturated carboxylic acid-based monomer unit (a2) exceeds 60% by mass, the processability is reduced due to an increase in resin viscosity, air bubbles are generated during molding due to an increase in water absorption, and the viscosity increases during production. It is not preferable because it becomes too high. In particular, by setting the content of the unsaturated carboxylic acid-based monomer unit (a2) to 2 to 60% by mass, it is possible to obtain good compatibility with the (meth)acrylic resin (B), and excellent transparency. A composition can be obtained.
Further, the unsaturated carboxylic acid-based monomer unit (a2) in the present embodiment includes an unsaturated carboxylic acid and its ester. Specifically, the unsaturated carboxylic acid-based monomer unit (a2) is , At least one or two 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) and more preferably contains a (meth)acrylic acid monomer unit (a2-1) and a (meth)acrylic acid ester monomer unit (a2-2).

- (Meth) acrylic acid monomer unit (a2-1) -
In the present embodiment, the (meth)acrylic acid monomer unit (a2-1) plays a role of improving oil resistance and heat resistance. (Meth)acrylic acid monomer units (a2-1) include acrylic acid and methacrylic acid. Especially from an industrial point of view, as the (meth)acrylic acid monomer unit (a2-1), these may be used alone or in combination of two or more. The (meth)acrylic acid monomer unit (a2-1) is particularly preferably methacrylic acid, which is highly effective in improving heat resistance.
In the present embodiment, the content range of the (meth)acrylic acid monomer unit (a2-1) is 2 to 30% by mass with respect to the total amount of the styrene-unsaturated carboxylic acid resin (A). is preferably 3 to 20% by mass, more preferably 4 to 17% by mass, and even more preferably 8 to 14% by mass. By making it 2% by mass or more, the effect of improving heat resistance can be obtained, and by making it 30% by mass or less, excessive increase in viscosity can be suppressed. In particular, when the amount is in the range of 8 to 13% by mass, it is possible to obtain a resin (A) that achieves both a high effect of improving heat resistance and suppressing gel generation to a level applicable to transparent sheets.

（上記一般式（１）中、Ｒ^１は、水素原子又は炭素原子数１～３のアルキル基を表し、Ｒ^２はエステル置換基を表わし、炭素原子数１～１２のアルキル基を表す。）で表されることが好ましい。
本実施形態において、（メタ）アクリル酸エステル単量体単位（ａ２－２）のエステル置換基（上記一般式（１）中のＲ^２）の炭素原子数としては１０以下が好ましく、より好ましくは８以下、より更に好ましくは４以下である。１０を上回ると耐熱性低下の効果が大きく、好ましくない。 - (Meth) acrylic acid ester monomer unit (a2-2) -
In the present embodiment, the (meth)acrylic acid ester monomer unit (a2-2) plays a role of improving oil resistance and strength. (Meth) acrylic acid ester monomer unit (a2-2), the following general formula (1)

(In general formula (1) above, R ¹ represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, R ² represents an ester substituent, and represents an alkyl group having 1 to 12 carbon atoms.) is preferably represented by
In the present embodiment, the number of carbon atoms in the ester substituent (R ² in the above general formula (1)) of the (meth)acrylic acid ester monomer unit (a2-2) is preferably 10 or less, more preferably 8 or less, more preferably 4 or less. If it exceeds 10, the effect of lowering the heat resistance is large, which is not preferable.

Examples of the (meth)acrylic acid ester monomer unit (a2-2) in the present embodiment include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, and (meth)acrylic acid. butyl, cyclohexyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, decyl (meth)acrylate and the like. These can be used singly or in combination. As the (meth)acrylic acid ester monomer, methyl (meth)acrylate or butyl (meth)acrylate is preferable from the viewpoint of industrial availability, and methyl methacrylate is particularly preferable from the viewpoint of suppressing a decrease in heat resistance. .
In the present embodiment, the upper limit of the content of the (meth)acrylic acid ester monomer unit (a2-2) with respect to the total amount of the styrene-unsaturated carboxylic acid resin (A) is (meth)acrylic acid ester The content range of the monomer unit (a2-2) is, for example, preferably 1 to 30% by mass, more preferably 2 to 25% by mass, still more preferably 3 to 21% by mass, still more preferably is 4 to 18% by weight, even more preferably 5 to 12% by weight.

<Preferred form of styrene-unsaturated carboxylic acid resin (A)>
The styrene-unsaturated carboxylic acid resin (A) of the present embodiment contains a (meth)acrylic acid monomer unit (a2-1) and a (meth)acrylic acid ester monomer unit (a2-2). It is preferably a multidimensional polymer. That is, the styrene-unsaturated carboxylic acid resin (A) of the present embodiment is a binary copolymer of a styrene monomer (a1) and a (meth)acrylic acid monomer unit (a2-1). A ternary copolymer obtained by copolymerizing a styrene-based monomer (a1), a (meth)acrylic acid monomer unit (a2-1), and a (meth)acrylic acid ester monomer unit (a2-2) It may be a polymer, and a copolymer having a styrene monomer (a1), a (meth)acrylic acid monomer unit (a2-1) and a methacrylic acid ester monomer unit (a2-2) is more preferable. As a result, the effect of improving compatibility with the (meth)acrylic resin (B), improving surface hardness, and improving low-temperature impact resistance or mechanical strength can be further obtained.
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 emphasizing improved compatibility with the (meth)acrylic resin (B) and the resulting high transparency, the styrene-unsaturated carboxylic acid resin (A) is a styrene monomer ( A terpolymer obtained by copolymerizing a1), a (meth)acrylic acid monomer unit (a2-1) and a (meth)acrylic acid ester monomer unit (a2-2) is preferred.

Further, in the polymer chain, unsaturated carboxylic acid ester monomer units such as (meth)acrylic acid ester monomer units (a2-2) are unsaturated carboxylic acid units such as (meth)acrylic acid units (a1-1) When it is arranged adjacent to the monomer unit, effects such as suppression of cross-linking reaction between unsaturated carboxylic acids can be obtained. The styrene-unsaturated carboxylic acid-based resin (A) in the present embodiment includes a styrene-based monomer unit (a1), a (meth)acrylic acid monomer unit (a2-1), and a (meth)acrylic acid ester unit When it has a monomer unit (a2-2), 40 to 97% by mass of the styrene-based monomer unit (a1) and (meth) acrylic The content of the acid monomer unit (a2-1) is 2 to 30% by mass, and the content of the (meth)acrylate monomer unit (a2-2) is 1 to 30% by mass. is preferred, and more preferably, the content of the styrene monomer unit (a1) is 50 to 95% by mass and the (meth)acrylic acid monomer unit (a2-1) is 3 to 25% by mass, and The content of the (meth)acrylic acid ester monomer unit (a2-2) is 2 to 25% by mass, more preferably 60 to 92% by mass of the styrenic monomer unit (a1) and (meth) The content of the acrylic acid monomer unit (a2-1) is 5 to 20% by mass, and the content of the (meth)acrylate monomer unit (a2-2) is 3 to 20% by mass. . By suppressing the content of the (meth)acrylic acid ester monomer unit (a2-2) to 40% or less, a composition having excellent fluidity during molding can be obtained.

The styrene-unsaturated carboxylic acid resin (A) of the present embodiment includes, for example, styrene monomer units of 40 to 97% by mass, methacrylic acid monomer units of 2 to 30% by mass, and methyl methacrylate monomers. It is preferably a copolymer (A-1) having 1 to 30% by mass of polymer units.

<Other monomer (a3)>
The styrene-unsaturated carboxylic acid-based resin (A) in the present embodiment includes the above-described styrene-based monomer unit (a1) and unsaturated carboxylic acid-based monomer unit (a2) ((meth)acrylic acid monomer (including the body unit (a2-1) and/or the (meth)acrylic acid ester monomer unit (a2-2).) may further have other monomer units (a3).
That is, in the present embodiment, the other monomer unit (a3) is a styrene monomer (a1), an unsaturated carboxylic acid monomer unit (a2) ((meth)acrylic acid monomer unit ( a2-1) and/or a (meth)acrylic acid ester monomer unit (a2-2)). may be copolymerized with monomers other than the two monomers shown in .
For example, monomers (a3) other than the three monomers shown above include maleic anhydride, maleic acid, fumaric acid, itaconic acid, (meth)acrylonitrile, dimethyl maleate, dimethyl fumarate, and diethyl fuma. rate, ethyl fumarate, maleimides, and nuclear-substituted maleimides.
In the present embodiment, when the styrene-unsaturated carboxylic acid resin (A) has another monomer (a3), the other monomer is added to the total amount of the styrene-unsaturated carboxylic acid resin (A) The content of (a3) is preferably 0 to 12% by mass, more preferably 0 to 5% by mass, and even more preferably 2% by mass or less.

<Characteristics of styrene-unsaturated carboxylic acid resin (A)>
In the styrene-unsaturated carboxylic acid-based resin (A) in the present embodiment, the styrene-based monomer unit (a1), the unsaturated carboxylic acid-based monomer unit (a2) ((meth)acrylic acid monomer unit (a2-1) and (meth)acrylic acid ester monomer units (a2-2).) and the content of other monomer units (a3) are determined using pyrolysis GC / MS. It can be quantified by a calibration curve prepared with a resin having a known mer unit.
The melt flow rate at 200° C. of the styrene-unsaturated carboxylic acid resin (A) in the present embodiment is preferably 0.3 to 3.0, more preferably 0.4 to 2.5, still more preferably 0. .4 to 2.0. A melt flow rate of 0.3 or more is preferable from the viewpoint of fluidity, and a melt flow rate of 3.0 or less is preferable from the viewpoint of mechanical strength of the resin. In the present disclosure, melt flow rate is a value measured in accordance with ISO 1133 at 200°C and a load of 49N.

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

The Vicat softening temperature of the styrene-unsaturated carboxylic acid resin (A) in the present embodiment is preferably higher than 100°C, more preferably 105 to 140°C, still more preferably 107 to 135°C, still more preferably 108 ~130°C, even more preferably between 115°C and 125°C. By setting the Vicat softening temperature of the styrene-unsaturated carboxylic acid resin (A) to more than 100°C, the effect of improving the heat resistance of the composition can be obtained, and by setting it to 140°C or less, the (meth)acrylic resin It becomes easy to knead with (B). The Vicat softening temperature measurement method used in this specification is based on ISO 306.

<Method for producing styrene-unsaturated carboxylic acid-based resin (A)>
A method for producing the styrene-unsaturated carboxylic acid resin (A) of the present embodiment will be described below.
The method for producing the styrene-unsaturated carboxylic acid-based resin (A) of the present embodiment comprises a styrene-based monomer (a1), an unsaturated carboxylic acid-based monomer (a2) ((meth)acrylic acid monomer A step of mixing the unit (a2-1) and/or (meth)acrylic acid ester monomer unit (a2-2)) with a solvent to prepare a mixed solution, and polymerizing the mixed solution to react It preferably comprises a polymerization step to produce a product and a step of recovering said reaction product.
The polymerization method for the styrene-unsaturated carboxylic acid-based resin (A) is not particularly limited, but for example, a radical polymerization method, particularly a bulk polymerization method or a solution polymerization method, can be preferably employed.
Specifically, the polymerization method mainly includes a polymerization step of polymerizing the polymerization raw material (monomer component) and a devolatilization step of removing volatiles such as unreacted monomers and polymerization solvents from the polymerization product. And prepare.

In the present embodiment, when the raw materials for polymerization are polymerized to obtain the styrene-unsaturated carboxylic acid resin (A), a polymerization initiator is typically included in the raw material composition for polymerization. Examples of polymerization initiators include organic peroxides such as 2,2-bis(t-butylperoxy)butane, 1,1-bis(t-butylperoxy)cyclohexane, n-butyl-4,4-bis(t -Butylperoxy)valerate and other peroxyketals, dialkylperoxides such as di-t-butylperoxide, t-butylcumylperoxide and dicumylperoxide, diacylperoxides such as acetylperoxide and isobutyrylperoxide, diisopropylperoxydi Examples include peroxydicarbonates such as carbonates, peroxyesters such as t-butylperoxyacetate, ketone peroxides such as acetylacetone peroxide, and hydroperoxides such as t-butyl hydroperoxide. Among them, 1,1-bis(t-butylperoxy)cyclohexane is preferred from the viewpoint of decomposition rate and polymerization rate.

In this embodiment, a chain transfer agent may be used as necessary during the polymerization of the styrene-unsaturated carboxylic acid resin (A). Examples of chain transfer agents include α-methylstyrene linear dimer, n-dodecylmercaptan, t-dodecylmercaptan, n-octylmercaptan and the like.

Solution polymerization using a polymerization solvent can be employed as the polymerization method for the styrene-unsaturated carboxylic acid resin (A). As the polymerization solvent, aromatic solvents such as toluene, ethylbenzene, propylbenzene, and butylbenzene are preferable, and if necessary, polar solvents such as alcohols or ketones are combined to form the styrene-unsaturated carboxylic acid resin (A). Solvent systems with adjusted solubility may also be used.
In the present embodiment, the polymerization solvent is preferably used in the range of 3 to 35 parts by mass with respect to 100 parts by mass of all the monomers constituting the styrene-unsaturated carboxylic acid resin (A), more preferably. is in the range of 5 to 30 parts by mass. If the amount of the polymerization solvent exceeds 35 parts by mass with respect to 100 parts by mass of the total monomers, the polymerization rate will decrease and the molecular weight of the obtained resin will also decrease, so that the mechanical strength of the resin will tend to decrease. If the amount of the polymerization solvent is less than 3 parts by mass, it may become difficult to control heat removal during polymerization. Addition of 3 to 35 parts by mass per 100 parts by mass of all monomers facilitates uniformity of quality and is preferable from the viewpoint of polymerization temperature control.

The apparatus used in the polymerization step for obtaining the styrene-unsaturated carboxylic acid-based resin (A) in the present embodiment is not particularly limited, and may be appropriately selected according to general polymerization methods for styrene-based resins. For example, in the case of bulk polymerization, a polymerization apparatus in which one or a plurality of complete mixing reactors are connected can be used. The devolatilization step is not particularly limited, and in the case of bulk polymerization, the polymerization is continued until the final unreacted monomer is preferably 50% by mass or less, more preferably 40% by mass or less. In order to remove volatile matter such as, devolatilization treatment is performed by a known method. For example, ordinary devolatilizers such as flash drums, twin-screw devolatilizers, thin film evaporators and extruders can be used, but devolatilizers with a small stagnant portion are preferred. The temperature of the devolatilization treatment is usually about 190 to 280°C, more preferably 190 to 260°C from the viewpoint of suppression of decomposition. The pressure of the devolatilization treatment is usually about 0.13 to 4.0 kPa, preferably 0.13 to 3.0 kPa, more preferably 0.13 to 2.0 kPa. Desirable devolatilization methods include, for example, a method of reducing the pressure under heating to remove the volatile matter, and a method of removing the volatile matter through an extruder or the like designed for the purpose of removing the volatile matter.

"(Meth)acrylic resin (B)"
The styrene resin composition in the present embodiment contains 20 to 45% by mass of (meth)acrylic resin (B) (also simply referred to as resin (B)) with respect to the total amount of the styrene resin composition. is preferred. The (meth)acrylic resin (B) has an unsaturated carboxylic acid monomer unit (b1). Containing a predetermined amount of the (meth)acrylic resin (B) in the resin composition contributes to improving the transparency and mechanical strength of the styrene resin composition as a whole.
The (meth)acrylic resin (B) used herein refers to a polymer having a content of unsaturated carboxylic acid monomer units (b1) of 60% or more. The polymer may be a random copolymer, a block copolymer, or an alternating copolymer, but the content of the unsaturated carboxylic acid-based monomer unit (b1) is 60% or more. Synthesized by random copolymerization It is preferably a resin that has been

The (meth)acrylic resin (B) of the present embodiment contains a high-molecular-weight component of 1,000,000 or more in an amount of preferably 3% by mass or less, more preferably 1% by mass or less, and even more preferably 0% by mass. be. If the composition has a high-molecular-weight component of 1,000,000 or more, components that are not dispersed during kneading remain, which may impair the transparency of the composition and may cause problems such as unmelted portions exhibiting fisheyes during transparent sheet molding. In addition, the high molecular weight component of 1,000,000 or more has an unsaturated carboxylic acid-based monomer (b1), and is contained in the styrene-based resin composition (meth) acrylic resin (B) Among them, the ratio of the (meth)acrylic resin (B) having a high molecular weight component of 1,000,000 or more is preferably 1.0% by mass or less with respect to the total amount of the styrene resin composition.
In the present embodiment, as a method for controlling the high molecular weight component of 1,000,000 or more in the (meth)acrylic resin (B) to 1.0% by mass or less, the unsaturated carboxylic acid monomer (b1) is subjected to radical polymerization. When doing, the type and amount of the unsaturated carboxylic acid-based monomer (b1), the type and amount of the chain transfer agent, the reaction temperature, the residence time, the type and amount of the polymerization initiator, the polymerization solvent can be controlled by the type and amount of the compound.
In the present invention, the number-average molecular weight (Mn), weight-average molecular weight (Mw), Z-average molecular weight (Mz) of the (meth)acrylic resin (B), and the proportion of high-molecular-weight components of 1,000,000 or more are described later. It is a value measured using gel permeation chromatography (GPC) as described in the Example column of .

The content of the (meth)acrylic resin (B) in the styrene resin composition is preferably 20 to 45% by mass, preferably 22 to 40% by mass, relative to the total amount (100% by mass) of the styrene resin composition. %, more preferably 24 to 35% by mass, and even more preferably 26 to 30% by mass. By setting the content of the (meth)acrylic resin (B) to 20% by mass or more, it is possible to improve oil resistance and contribute to the improvement of hot oil resistance. A decrease in the heat resistance improved by the saturated carboxylic acid-based resin (A) can be suppressed.
The unsaturated carboxylic acid-based monomer unit (b1) constituting the (meth)acrylic resin (B) of the present embodiment is a (meth)acrylic acid monomer unit (b1-1) and (meth)acrylic acid It is preferably at least one or two or more repeating units selected from the group consisting of ester monomer units (b1-2), and consists of (meth) acrylic acid ester monomer units (b1-2) More preferably, it is a random copolymer of two or more repeating units selected from the group.

- (Meth) acrylic acid monomer (b1-1) -
In the present embodiment, the (meth)acrylic acid monomer unit (b1-1) includes acrylic acid or methacrylic acid. Especially from an industrial point of view, as the (meth)acrylic acid monomer unit (b1-1), these may be used alone or in combination of two or more. The (meth)acrylic acid monomer unit (b1-1) is particularly preferably methacrylic acid, which is highly effective in improving heat resistance.
In the present embodiment, the upper limit of the content of the (meth)acrylic acid monomer unit (b1-1) with respect to the total amount of the (meth)acrylic resin (B) is 50% by mass or less and 40% by mass or less. , 30% by mass or less, 20% by mass or less, 16% by mass or less, and 13% by mass or less, in that order. The lower limit of the content is preferably 0% by mass or more, 0.5% by mass or more, 1% by mass or more, 2% by mass or more, 5% by mass or more and 10% by mass or more in this order. The content of the (meth)acrylic acid monomer unit (b1-1) can be any combination of the above upper limit and the above lower limit. The content range of the (meth)acrylic acid monomer unit (b1-1) is, for example, preferably 0 to 50% by mass, more preferably 2 to 40% by mass, and still more preferably 2 to 30% by mass. %, more preferably 4 to 20% by mass, still more preferably 5 to 16% by mass, particularly preferably 6 to 13% by mass.

-(Meth) acrylic acid ester monomer (b1-2)-
The (meth)acrylic acid ester monomer units (b1) constituting the (meth)acrylic resin (B) of the present embodiment include methacrylic acid ester monomer units and acrylic acid ester monomer units. Further, the (meth)acrylate ester monomer unit (b1-2) includes methyl acrylate, ethyl acrylate, (n-butyl) acrylate, (2-ethylhexyl) acrylate, and (n-octyl) acrylate. ), benzyl acrylate, methyl methacrylate, butyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, methacrylate (2-ethylhexyl), methacrylate (n-octyl), Benzyl methacrylate and the like can be mentioned, and methyl acrylate, (n-butyl) acrylate, and methyl methacrylate are preferred from the viewpoint of industrial availability and low cost.
As a combination of monomer units constituting the (meth)acrylic resin (B) of the present embodiment, from the viewpoint of achieving both heat resistance and thermal decomposability, among the monomer units listed above, methacrylic A copolymer of an acid ester species and an acrylic ester species is preferred, and a methyl methacrylate-methyl acrylate copolymer is more preferred.
In the present embodiment, the upper limit of the content of the (meth)acrylic acid ester monomer unit (b1-2) with respect to the total amount of the (meth)acrylic resin (B) is 100% by mass or less, 99% by mass. 98% by mass or less, 80% by mass or less, 75% by mass or less, and 65% by mass or less are preferred in that order. The lower limit of the content is preferably 0% by mass or more, 0.5% by mass or more, 1% by mass or more, 2% by mass or more, 5% by mass or more and 10% by mass or more in this order. The content of the (meth)acrylic acid ester monomer unit (b1-2) can be any combination of the above upper limit and the above lower limit. The content range 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, and still more preferably 2 to 98% by mass. % by mass, more preferably 4 to 98% by mass, even more preferably 5 to 98% by mass, particularly preferably 6 to 98% by mass.

<Preferred form of (meth)acrylic resin (B)>
A preferred (meth)acrylic resin (B) of the present embodiment is a random copolymer of a methacrylic acid ester monomer and an acrylic acid ester monomer, and the methacrylic acid ester monomer is Specifically, methyl methacrylate, ethyl methacrylate, and (n-butyl) methacrylate are preferred from the viewpoint of industrial availability, and methyl methacrylate is particularly preferred from the viewpoint of heat resistance. On the other hand, as the acrylate ester monomer, specifically, methyl acrylate, ethyl acrylate, and (n-butyl) acrylate are preferable from the viewpoint of industrial availability, and particularly methyl acrylate from the viewpoint of heat resistance. is preferred. From the above, methyl methacrylate-methyl acrylate random copolymer is most preferable. By using a methyl methacrylate-methyl acrylate random copolymer, the styrene-unsaturated carboxylic acid-based resin (A) suppresses the decrease in heat resistance improved by the styrene-unsaturated carboxylic acid-based resin (A). excellent compatibility can be obtained.
In this case, the content of methyl methacrylate is preferably in the range of 70 to 99% by mass, more preferably 80% by mass, relative to the total amount (100% by mass) of the (meth)acrylic resin (B). ~99.5% by mass, more preferably 85 to 98% by mass. In particular, when the amount is 85 to 98% by mass, compatibility with the styrene-unsaturated carboxylic acid resin (A) can be improved, leading to improvement in strength and transparency of the composition. The content of methyl acrylate is preferably in the range of 1 to 30% by mass, more preferably 1.5 to 30% by mass, relative to the total amount (100% by mass) of the (meth)acrylic resin (B). 20% by mass, more preferably 2 to 15% by mass. In particular, by setting the content of methyl acrylate to 1% by mass or more, the unzipping reaction during thermal decomposition of the (meth)acrylic resin (B) can be suppressed, and other resins in the range of 200 to 300 ° C. It becomes able to withstand kneading with extrusion and molding.

<Other monomer (b2)>
The (meth)acrylic resin (B) of the present embodiment is a monomer other than the (meth)acrylic acid monomer (b1-1) and the (meth)acrylic acid ester monomer unit (b1-2) described above. It may further have a mer unit (b2). That is, the other monomer unit (b2) is an unsaturated carboxylic acid-based monomer unit (b1) ((meth)acrylic acid monomer (b1-1) and/or (meth)acrylic acid ester monomer (including the body (b1-2).) without any particular limitation, as long as it is copolymerizable with the monomers other than the above-described monomers, as long as it does not impair the effects of the invention. good. Examples of monomers (b2) other than the above-mentioned monomers include styrene, maleic anhydride, maleic acid, fumaric acid, itaconic acid, dimethyl maleate, dimethyl fumarate, diethyl fumarate, ethyl fumarate, Maleimide, nuclear-substituted maleimide, and the like.
In the present embodiment, the content of the other monomer unit (b2) is preferably 0 to 30% by mass, preferably 0 to 20% by mass, based on the total amount of the (meth)acrylic resin (B). more preferably 0 to 15% by mass.

The weight average molecular weight (Mw) of the (meth)acrylic resin (B) is preferably 70,000 to 900,000, more preferably 80,000 to 850,000, still more preferably 90,000 to 500,000, still more preferably 110,000 to 400,000. be. By setting the weight average molecular weight (Mw) of the (meth)acrylic resin (B) to 70,000 or more, strength can be imparted when kneaded with the styrene-unsaturated carboxylic acid resin (A), and 900,000 or less. By doing so, the difference in viscosity from the styrene-unsaturated carboxylic acid resin (A) can be suppressed, and the (meth)acrylic resin (B) can be dispersed well in the styrene resin composition, In addition, generation of unmelted matter derived from the (meth)acrylic resin (B) can be suppressed, and an extruded sheet having a good appearance can be obtained using the composition.
Further, as described above, the (meth)acrylic resin (B) of the present embodiment is composed of a high molecular weight component of 1,000,000 or more and other molecular weight components of less than 1,000,000. The ratio of the molecular weight component to the total amount of the styrene resin composition is 1.0% by mass or less, preferably 0.3% by mass or less. It is possible to prevent the generation of unmelted substances due to the difference in viscosity from the acid-based resin (A), which is preferable in terms of appearance and strength.
The Vicat softening temperature of the (meth)acrylic resin (B) of the present embodiment is preferably higher than 100°C, more preferably 105 to 125°C. In particular, by setting the temperature to 105° C. or higher, it is possible to suppress a decrease in heat resistance when kneading with the styrene-unsaturated carboxylic acid resin (A), and it is possible to obtain a styrene resin composition excellent in heat resistance and resistance to hot oils. . The Vicat softening temperature measurement method used in this specification is based on ISO 306.

<(Meth)acrylic Acid Monomer or (Meth)Acrylic Acid Ester Monomer in Styrenic Resin Composition>
In the present embodiment, the content of all (meth)acrylic acid monomer units contained in the styrene resin composition is 4.0 to 10 with respect to the total amount (100% by mass) of the styrene resin composition. % by mass, preferably 5.0 to 8.5 mass %, more preferably 5.5 to 7.0 mass %. When the content of the (meth)acrylic acid monomer in the entire composition is within the above range, a sufficient effect of improving heat resistance can be obtained.
In addition, since the content of all (meth)acrylic acid monomers indicates the total amount of (meth)acrylic acid monomer units present in the styrene resin composition, resin (A), resin ( B), the contents of the (meth)acrylic acid monomer units in the rubber-like component (C) and the resin (C-2-2) are also converted.
The resin (C-2-2) refers to a polymer matrix component (C-2-2) of impact-resistant polystyrene (C-2) described later.

In the present embodiment, the content of all (meth)acrylic acid ester monomer units contained in the styrene resin composition is 20 to 40% by mass with respect to the total amount (100% by mass) of the styrene resin composition. It is preferably contained, preferably 22 to 38% by mass, more preferably 24 to 36% by mass, still more preferably 26 to 34% by mass. When the content of the (meth)acrylic acid ester monomer in the entire composition is within the above range, the effect of improving oil resistance and strength can be sufficiently obtained.
The content of all (meth)acrylic acid ester monomers means the total amount of (meth)acrylic acid ester monomer units present in the styrene-based resin composition. Each content of the (meth)acrylic acid ester monomer units in the resin (B), the rubber component (C) and the resin (C-2-2) is also converted.

By controlling the (meth)acrylic acid monomer unit and the (meth)acrylic acid ester monomer contained in the styrenic resin composition within the above range, the heat resistance by the (meth)acrylic acid monomer unit To obtain a styrenic resin composition and a sheet formed by molding the same, which can simultaneously and efficiently obtain an improvement effect and an oil resistance improvement effect by a (meth)acrylic acid ester monomer unit, and as a result, has excellent heat oil resistance. be able to.

<Method for producing (meth)acrylic resin (B)>
The method for producing the (meth)acrylic resin (B) of the present embodiment is not particularly limited. It can be produced by a process such as solution polymerization in which a solvent is added, or suspension polymerization in which an organic layer is dispersed in water with a suspending agent.

<Rubber component (C)>
The rubber component (C) in the present embodiment is a general term for polymers containing a conjugated diene monomer (c3), and imparts the effect of improving the impact resistance including at low temperatures to the styrenic resin composition of the present invention. do. Specifically, the rubber component (C) includes an MBS resin (C-1) (also referred to as a (meth)acrylic-butadiene-styrene copolymer (C-1)) described below, as well as impact-resistant polystyrene ( Rubber-like graft particles (C-2-1) containing a graft polymer derived from C-2) (e.g., butadiene rubber crosslinked particles), and copolymerization with conjugated diene monomers (c3) derived from other additives It is the sum of the combined components.

In the present embodiment, the following formula (i) representing the mixing ratio of the styrene-unsaturated carboxylic acid resin (A) and the (meth)acrylic resin (B) is within the range of 1.0 to 4.0. The absolute value of the difference between the refractive index of the matrix mixture containing no rubber component (C) and the refractive index of the rubber component (C) is preferably in the range of 0 to 0.01, preferably 0 to 0.009. is more preferably 0 to 0.008, even more preferably 0 to 0.007, and most preferably 0 to 0.006.
Formula (i):
(Content of styrene-unsaturated carboxylic acid resin (A))/((Meth)acrylic resin (B) content)
When the refractive index difference is in the range of 0 to 0.01, higher levels of heat resistance, transparency and low-temperature impact resistance can be exhibited.
The matrix mixture not containing the rubber component (C) (also referred to simply as the matrix mixture) is the methyl ethyl ketone soluble portion in the styrene resin composition of the present embodiment, and is a styrene-unsaturated carboxylic acid-based The resin (A) and the (meth)acrylic resin (B) are the main components, and the mixture ratio (A)/(B) represented by the above formula (i) is within the range of 1 to 4, and methyl ethyl ketone Refers to a mixture of soluble polymers and additives. Therefore, the polymer matrix component (C-2-2) contained in the impact-resistant polystyrene (C-2), which is a component added as necessary to the styrene resin composition of the present embodiment, the acrylic elastomer , and other additives such as resins and antioxidants are classified as matrix mixtures that do not contain the rubber component (C).
In other words, the matrix mixture that does not contain the rubber component (C) in this specification is a general term for components other than the rubber component (C) in the styrene resin composition of the present embodiment.
For example, when the styrenic resin composition of the embodiment does not contain the high-impact polystyrene (C-2), the matrix mixture that does not contain the rubber component (C) contains the styrene-unsaturated carboxylic acid resin (A) and ( It essentially contains a meth)acrylic resin (B), and if necessary, an acrylic elastomer, other resins, and additives such as antioxidants. On the other hand, when the styrenic resin composition of the embodiment contains the high-impact polystyrene (C-2), the matrix mixture containing no rubber component (C) contains the styrene-unsaturated carboxylic acid resin (A), ( Essentially contains polymer matrix component (C-2-2) contained in meth)acrylic resin and impact-resistant polystyrene (C-2), and if necessary, acrylic elastomer, other resins and additives such as antioxidants . In the former case, the rubber component (C) may contain MBS resin (C-1). On the other hand, in the latter case, the rubber component (C) may contain rubber-like graft particles (C-2-1), or may contain rubber-like graft particles (C-2-1) and MBS resin (C-1). sell.

The content of the rubber component (C) of the present embodiment is 1 to 45 parts by mass, preferably 3 to 40 mass %, more preferably 5 to 35 mass %, relative to the total amount of the styrene resin composition. Even more preferably 10 to 30% by mass, most preferably 12 to 25% by mass. When the content of the rubber component (C) is 1% by mass or more, an effect of improving impact resistance at room temperature can be obtained, and when it is 5% by mass or more, an effect of improving impact resistance at around 0°C can be obtained. When the content is at least 10% by mass, the effect of improving low-temperature impact resistance at −30° C., which is assumed to be the temperature during frozen transportation of food, can be obtained.
The content of the rubber component (C) includes the polymer containing the conjugated diene monomer (c3) and the phase containing the polymer composed of monomer units other than the conjugated diene monomer unit (c3). . Therefore, for example, when the rubber component (C) is salami particles having a salami structure to be described later, a plurality of domains of a polymer composed of monomer units other than the conjugated diene monomer unit (c3) and conjugation containing the domains It is the total amount of the polymer containing the diene monomer (c3).

As the form of the copolymer of the conjugated diene monomer (c3) in the rubber component (C) of the present embodiment, a random copolymer, a graft copolymer, a block copolymer, or the like can be freely selected, but is preferred. is graft copolymerization or block copolymerization, more preferably graft copolymerization, and most preferably monomers such as styrene, methyl methacrylate, and butyl methacrylate are added to the core mainly composed of crosslinked conjugated diene monomer units. is a crosslinked rubber particle obtained by graft copolymerization.

A preferred morphology of the crosslinked rubber particles is core-shell particles having a core containing a polymer composed of a monomer unit other than the conjugated diene monomer unit (c3) and a shell containing the conjugated diene monomer unit (c3). , and salami particles formed by entrapping a polymer composed of a monomer unit other than the conjugated diene monomer unit (c3), and rubber crosslinked particles having the above two types of morphologies may be used in combination. .

The refractive index of the rubber component (C) of the present embodiment is preferably from 1.530 to 1.565, more preferably from 1.533 to 1.560, still more preferably from 1.536 to 1.555, still more preferably is in the range of 1.539 to 1.550. In particular, by setting the refractive index of the rubber component (C) in the range of 1.539 to 1.550, the rubber component (C) and the matrix mixture not containing the rubber component (C) in the styrene resin composition, that is, styrene - Refractive index difference from polymer matrix component (C-2-2) contained in unsaturated carboxylic acid resin (A), (meth)acrylic resin (B) and impact-resistant polystyrene resin (C-2) can be easily adjusted and a styrene-based resin composition excellent in transparency can be obtained.
The styrenic resin composition in this embodiment contains 1 to 45% by mass of the rubber component (C) with respect to the total amount of the styrenic resin composition. The rubber component (C) comprises an MBS resin (C-1) having a styrene-based monomer unit (c1), a (meth)acrylic acid ester monomer unit (c2) and a butadiene unit, and an impact-resistant polystyrene ( It is preferably one or more components selected from the group consisting of rubber-like graft particles (C-2-1) derived from C-2). Since the resin composition contains a predetermined amount of the predetermined rubber component (C), it contributes to the improvement of the mechanical strength of the styrenic resin composition as a whole.
When the rubber component (C) of the present embodiment takes the form of particles, the average particle size is preferably 50 to 300 nm, more preferably 80 to 270 nm, still more preferably 100 to 250 nm, still more preferably 150 to 220 nm. is. By setting the average particle size of the MBS resin (C-1) in the range of 150 to 220 nm, the effect of imparting strength to the styrene-based resin composition is excellent.
The average particle size in this specification is measured using the method described in the Examples section below.

<<MBS resin (C-1)>>
In the styrene resin composition of the present embodiment, a copolymer mainly composed of a styrene monomer unit (c1) and a (meth)acrylic acid ester monomer unit (c2) is a butadiene monomer unit. It is preferable to contain an MBS resin (C-1) grafted onto rubber-like particles containing
The content of the MBS resin (C-1) is preferably 1 to 45% by mass, more preferably 3 to 40% by mass, still more preferably 4 to 35% by mass, based on the total amount of the styrene resin composition. % by weight, more preferably 5 to 30% by weight, most preferably 10 to 20% by weight. By making it 1% by mass or more, mechanical strength and low-temperature impact resistance can be improved, and by making it 45% by mass or less, it is possible to prevent deterioration in heat resistance and rigidity.

As the styrene-based monomer (c1) constituting the MBS resin (C-1), the examples of the styrene-based monomer (a1) are cited. Also, the styrene-based monomer (c1) can be used singly or in combination of two or more.

The (meth)acrylic acid ester monomer units (c2) constituting the MBS resin (C-1) include methacrylic acid ester monomer units and acrylic acid ester monomer units. Further, the (meth)acrylate monomer (c2) includes methyl acrylate, ethyl acrylate, (n-butyl) acrylate, (2-ethylhexyl) acrylate, (n-octyl) acrylate, acrylic Benzyl acid, methyl methacrylate, butyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, methacrylate (2-ethylhexyl), methacrylate (n-octyl), benzyl methacrylate Methyl acrylate, (n-butyl) acrylate, and methyl methacrylate are more preferred, and methyl methacrylate is particularly preferred, from the viewpoint of industrial availability and low cost.

Here, the copolymer to be grafted onto the rubber-like particles containing butadiene monomer units is mainly composed of styrene-based monomer units (c1) and (meth)acrylic acid ester monomers (c2), The ratio of the total of the (meth)acrylic acid ester monomer unit (c2) and the styrene monomer unit (c1) to the total monomer units of the copolymer to be grafted is 92% by mass or more. means. This proportion is preferably 94% by mass or more, more preferably 96% by mass or more.

By blending MBS resin (C-1), a styrenic resin composition having excellent improvement in mechanical strength and low-temperature impact resistance can be obtained. However, if the blending amount is less than 1 mass, the improvement in mechanical strength tends to be low. On the other hand, when the blending amount exceeds 45% by mass, the content of the butadiene monomer units in the resin composition increases, and the rigidity and heat resistance of the obtained composition and molded article tend to decrease, and the sheet etc. appearance tends to deteriorate.

The content of butadiene monomer units in the MBS resin (C-1) is preferably 30 to 90% by mass, more preferably 40 to 85% by mass, even more preferably 50 to 80% by mass, still more preferably 55 to 75% by mass. The higher the content of butadiene monomer units, the greater the improvement in mechanical strength with a small addition amount, which is preferable. On the other hand, if the content of the butadiene monomer unit is too high, the (meth)acrylic acid ester monomer unit (c2) (e.g., methyl methacrylate monomer unit) and the styrene monomer unit (c1) (e.g., The content of the graft copolymer mainly composed of styrene monomer units) is reduced, the compatibility with the styrene-unsaturated carboxylic acid resin (A) is reduced, and the transparency is deteriorated due to a decrease in the refractive index. , cause a decrease in heat resistance.

The content of the styrene-based monomer unit (c1) in the MBS resin (C-1) is preferably 20 to 70% by mass, more preferably 22 to 60% by mass, still more preferably 24 to 50% by mass, and still more It is preferably 26 to 55% by mass. It is preferable that the content of the styrene-based monomer (c1) is in the range of 20 to 70% by mass, because the compatibility with the styrene-unsaturated carboxylic acid-based resin (A) is excellent.

The content of the (meth)acrylate monomer unit (c2) in the MBS resin (C-1) is preferably 10 to 40% by mass, more preferably 2 to 30% by mass, and still more preferably 3 to 20% by mass. %, more preferably 4 to 15 mass %. When the content of the (meth)acrylic acid ester monomer unit (c2) is in the range of 20 to 70% by mass, the compatibility with the (meth)acrylic resin (B) is excellent, which is preferable.

The mass ratio of the styrene-based monomer unit (c1) and the (meth)acrylic acid ester monomer unit (c2) constituting the MBS resin (C-1) is preferably 95/5 to 60/40, and more The range is preferably 92/8 to 70/30, more preferably 90/10 to 75/25. In particular, a styrenic resin composition having excellent transparency can be obtained by adjusting the ratio within the range of 90/10 to 75/25.
As the MBS resin (C-1) in the present embodiment, a copolymer having styrene monomer units and methyl methacrylate monomer units is grafted onto rubber-like particles composed of butadiene monomer units. It is preferably a polymer.

As a method for producing the MBS resin (C-1) of the present embodiment, after producing butadiene rubber latex particles, the styrene-based monomer (c1) and the (meth)acrylic acid ester monomer (c2) are mixed. An emulsion polymerization method of polymerizing is preferred.

When the MBS resin (C-1) of the present embodiment takes the form of rubber particles, the average particle size is preferably 50 to 300 nm, more preferably 80 to 270 nm, still more preferably 100 to 250 nm, and even more preferably 150-220 nm. By setting the average particle size of the MBS resin (C-1) in the range of 150 to 220 nm, the effect of imparting strength to the styrene-based resin composition is excellent.
The average particle size in this specification is measured using the method described in the Examples section below.

<<Impact-resistant polystyrene (C-2)>>
As a preferred aspect of the present embodiment, the styrenic resin composition preferably contains impact-resistant polystyrene (C-2) (also referred to simply as resin (C-2)). By containing an appropriate amount of impact-resistant polystyrene (C-2) in the styrene resin composition, a styrene resin composition excellent in strength and a molded article obtained by molding the composition can be obtained.
The impact-resistant polystyrene (C-2) of the present embodiment is a polymer matrix component (C-2-2) of a resin composed of a styrene-based monomer (c1) and optionally other monomers (c5). in which the rubber-like graft particles (C-2-1) are dispersed, and in the presence of the rubber-like polymer (c4), the styrene-based monomer (c1) and optionally other monomers (c5 ) can be obtained by polymerizing.
That is, the impact-resistant polystyrene (C-2) comprises a resin polymer matrix component (C-2-2) comprising a styrene monomer (c1) and optionally other monomers (c5), and a rubber Graft particles (C-2-1) are preferred. The rubber-like graft particles (C-2-1) preferably have the conjugated diene monomer unit (c3) as a constituent component.
In this specification, the rubber-like graft particles (C-2-1) in the impact-resistant polystyrene (C-2) are classified as the rubber component (C), but the impact-resistant polystyrene (C-2 ) can be contained in the styrenic resin composition as the resin (C-2-2).

The content of the impact-resistant polystyrene (C-2) in the styrene-based composition of the present embodiment is preferably 0.5 to 30% by mass, more preferably 1 .2 to 18% by weight, more preferably 1.7 to 8% by weight. By setting the content of the impact-resistant polystyrene (C-2) in the range of 0.1 to 30% by mass, a composition having excellent transparency and strength can be obtained.
In addition, since the styrene-based monomer (c1) of the present embodiment is the same as the styrene-based monomer (a1) described above, the content thereof is incorporated.

- Rubber-like graft particles (C-2-1) -
The rubber-like graft particles (C-2-1) in the present embodiment are obtained by graft-copolymerizing a rubber-like polymer (c4) described later with a styrene-based monomer (c1) and other monomers (c5), Refers to the rubber graft particles that are formed. It is preferable that the rubber-like graft particles (C-2-1) contain a polymer containing the styrene-based monomer unit (c1). As the form of the encapsulation, a core-shell type dispersed particle having a rubber-like polymer (c4) as a core and a polymer having a styrene monomer unit (c1) as a shell, or a styrene monomer unit ( So-called salami-structure dispersed particles in which a polymer phase having c1) is encapsulated by a plurality of rubber-like polymers (c4) may also be used. The content of the rubber-like graft particles (C-2-1) contained in the impact-resistant polystyrene (C-2) is preferably 5 to 40% by mass with respect to the total amount of the impact-resistant polystyrene (C-2). , more preferably 10 to 37 mass %, more preferably 15 to 35 mass %.

-Polymer matrix component (C-2-2)-
The content of the polymer matrix component (C-2-2) contained in the impact-resistant polystyrene (C-2) of the present embodiment is 60 to 95 with respect to the total amount of the impact-resistant polystyrene (C-2). % by mass is preferable, 63 to 90% by mass is more preferable, and 65 to 85% by mass is even more preferable.
Also, the polymer matrix component (C-2-2) can be composed of a polymer having a styrenic monomer unit (c1) and optionally other monomers (c5). Specifically, examples of the polymer constituting the polymer matrix component (C-2-2) include polystyrene and copolymers of styrene-based monomer units (c1) and other monomer units (c5). be done.

-Rubber-like polymer (c4)-
In the present embodiment, the rubber-like polymer (c4) constituting the rubber-like graft particles (C-2-1) in the impact-resistant polystyrene (C-2) includes polybutadiene, polyisoprene, natural rubber, and polychloroprene. , a styrene-butadiene copolymer, an acrylonitrile-butadiene copolymer and the like can be used, but from an industrial point of view, polybutadiene and a styrene-butadiene copolymer are preferred. Polybutadiene may be high-cis polybutadiene with a high cis content, low-cis polybutadiene with a low cis content, or both of them, but low-cis polybutadiene is preferred from the viewpoint of industrial ease of handling. The structure of the styrene-butadiene copolymer may be a random structure, a block structure, or a combination thereof. These rubber-like polymers may be used singly or in combination of two or more. Saturated rubber obtained by hydrogenating butadiene rubber can also be used.

- Other monomer (c5) -
Other monomers (units) (c5) that are optional components of the impact-resistant polystyrene (C-2) of the present embodiment include (meth)acrylic acid ester monomers (units) (c2), acrylic acid, methacrylic acid, methyl acrylate, ethyl acrylate, propyl acrylate, (n-butyl) acrylate, isopropyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, methacrylate (n-butyl), (Meth)acrylic acid ester monomers such as isopropyl methacrylate can be used, but (n-butyl) acrylate and methyl methacrylate are preferred from the viewpoint of industrial availability.
In the present embodiment, the content of the other monomer (unit) (c5) in the impact-resistant polystyrene (C-2) is 10 to 60 mass with respect to the total amount of the impact-resistant polystyrene (C-2). %, more preferably 13 to 50% by mass.

-Conjugated diene monomer unit (c3)-
In this embodiment, the rubber-like graft particles (C-2-1) or rubber-like polymer (c4) is preferably formed from a conjugated diene monomer (c3). In the present specification, the conjugated diene monomer unit (c3) is a diolefin having a pair of conjugated double bonds among the monomer units constituting the rubber-like graft particles (C-2-1). , for example, chemical structures such as 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 1,3-hexadiene The content of the conjugated diene monomer unit (c3) in the impact-resistant polystyrene (C-2) and the styrenic resin composition is determined by the procedure described in the Examples section below, or an equivalent method can be measured.

In the present embodiment, the content of the conjugated diene monomer unit (c3) in the impact-resistant polystyrene (C-2) is preferably 3.0 with respect to the total amount of the impact-resistant polystyrene (C-2). ~15.0% by mass, more preferably 5.0 to 13.0% by mass, and even more preferably 7.0 to 12.0% by mass.

-Average particle size of rubber-like graft particles (C-2-1)-
Rubber-like graft particles (C-2-1), which are rubber-containing components in impact-resistant polystyrene (C-2) in the present embodiment, exist as particles in the styrene-based resin composition. The average particle size of the rubber-like graft particles (C-2-1) in this case is preferably 0.3 to 5.0 μm, more preferably 0.5 to 4.0 μm, still more preferably 0.7 to 3.0 μm. is. The impact-resistant polystyrene (C-2) is obtained by polymerizing the styrenic monomer (c1) and other monomers (c5) in the presence of the rubbery polymer (c4) in a reactor equipped with a stirrer. However, the average particle size of the rubber-like graft particles (C-2-1) can be adjusted by adjusting the rotational speed of the stirrer, the molecular weight of the rubber-like polymer used, and the like. In the present disclosure, the average particle size of the rubber-like graft particles (C-2-1) is a value measured from a cross-sectional image observed with a transmission electron microscope. The rubber-like polymer particles are stretched in the biaxially stretched sheet described later depending on the stretching ratio, and the particle diameter increases by about 400% at maximum.
The average particle size in this specification is measured using the method described in the Examples section below.

In the present embodiment, the melt flow rate of impact-resistant polystyrene (C-2) at 200° C. is preferably 1.0 to 10.0 g/10 minutes, more preferably 2.0 to 8.0 g/10 minutes. , and more preferably 2.5 to 7.0 g/10 minutes. If the melt flow rate is in the range of 1.0 to 10.0 g / 10 minutes, the miscibility with the styrene-unsaturated carboxylic acid resin (A) and the (meth)acrylic resin (B) is good, and mechanical It also has good mechanical strength. In the present disclosure, melt flow rate is a value measured in accordance with ISO 1133 at 200°C and a load of 49N.

The method for producing the impact-resistant polystyrene (C-2) is not particularly limited, but in the presence of a rubber-like polymer, the styrenic monomer (c1) and optionally other monomers (c5) , and bulk polymerization (or solution polymerization) that polymerizes a solvent, bulk-suspension polymerization that shifts to suspension polymerization in the middle of the reaction, or in the presence of latex particles that are a rubber-like polymer (c4), a styrene-based monomer It can be produced by emulsion graft polymerization in which (c1) is polymerized. In bulk polymerization, a rubber-like polymer (c4), a styrene monomer (c1), and, if necessary, other monomers, an organic solvent, an organic peroxide, and/or a chain transfer agent are added to the mixture. The solution can be produced by continuously supplying the solution to a polymerization apparatus comprising a complete mixing reactor or tank reactor and a plurality of tank reactors connected in series.

"Monohydric alcohol having 10 or more carbon atoms"
The styrenic resin composition in the present embodiment may contain a monohydric alcohol having 10 or more carbon atoms (hereinafter also simply referred to as alcohol), if necessary. The monohydric alcohol having 10 or more carbon atoms is an optional component, suppresses gelation of the styrene-unsaturated carboxylic acid resin (A) during molding, and provides a styrene resin composition and a styrene resin with good appearance. It contributes to improving the appearance of molded articles made of the composition. The content of the monohydric alcohol having 10 or more carbon atoms is 0.01 to 1.0 mass%, preferably 0.03 to 0, relative to the total amount (100 mass%) of the styrene resin composition. 0.8% by weight, more preferably 0.05-0.6% by weight, and even more preferably 0.07-0.5% by weight. By setting the content of the monohydric alcohol having 10 or more carbon atoms to 0.01% by mass or more, gelation of the styrene-unsaturated carboxylic acid resin (A) during molding can be suppressed. A decrease in heat resistance and generation of odor can be suppressed by making the content 0% by mass or less. By setting the content of the monohydric alcohol having 10 or more carbon atoms to 0.07 to 0.5% by mass, a sufficient gel suppression effect can be obtained without reducing the heat resistance.

The monohydric alcohol having 10 or more carbon atoms is an alcohol having 10 or more carbon atoms containing one hydroxyl group, and may contain a heteroatom such as oxygen or nitrogen in the carbon chain constituting the alcohol. The chain may contain bonds other than single bonds, such as double bonds, triple bonds, ester bonds, and amide bonds. The number of carbon atoms is preferably 16 or more, more preferably 17 or more, and still more preferably 18 or more and 50 or less. The monohydric alcohol having 10 or more carbon atoms may be contained in the styrene-based resin composition or the molded article made of the styrene-based resin composition. Therefore, a monohydric alcohol having 10 or more carbon atoms is present (or added) in the polymerization solution used when polymerizing the styrene-unsaturated carboxylic acid resin (A) or (meth)acrylic resin (B). Thus, the monohydric alcohol may remain in the resin composition that is the final product, or when kneading the styrene-unsaturated carboxylic acid resin (A) and the (meth)acrylic resin (B) Although it may be added to and mixed in an extruder, it is preferable to add the styrene-unsaturated carboxylic acid resin (A) during polymerization from the viewpoint of cost.

In the present 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., the volatility tends to be high and an offensive odor tends to occur during molding.

The monohydric alcohol having 10 or more carbon atoms is not particularly limited, but examples 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, polyoxyethylene alkyl ethers and the like.

（上記一般式（２）中、Ｒは炭素原子数１２～２０のアルキル基であり、Ｘはエチレンオキサイドの平均付加数を表し、１～１５の整数である。） The above polyoxyethylene alkyl ethers are preferably compounds represented by the following general formula (2).

(In general formula (2) above, R is an alkyl group having 12 to 20 carbon atoms, X represents the average number of ethylene oxide additions, and is an integer of 1 to 15.)

Specific product names of preferred monohydric alcohols having 10 or more carbon atoms include "Fine Oxocol 180" manufactured by Nissan Chemical Industries, Ltd. and "Emulgen 109P" manufactured by Kao Corporation.
"Other Ingredients"
In addition to the above components, the styrenic resin composition of the present embodiment is made by adding various additives commonly used in styrenic resins to achieve known effects. can also Examples thereof include stabilizers, higher fatty acid surfactants, antioxidants, ultraviolet absorbers, lubricants, release agents, plasticizers, antiblocking agents, antistatic agents, antifogging agents, and mineral oils. In addition, elastomers such as styrene-maleic anhydride copolymer, methyl methacrylate-butyl acrylate block copolymer, methyl methacrylate-(2-ethylhexyl) acrylic acid block copolymer, styrene-butadiene block copolymer, etc. The reinforcing material may also be added within a range that does not impair the physical properties. The method of blending is not particularly defined, but for example, a method of adding and polymerizing during polymerization, or mixing additives in advance with a blender before melt-kneading after polymerization, and then using an extruder or Banbury mixer. The method of melt-kneading, etc. are mentioned.

Examples of antioxidants that can be used in the present embodiment include octadecyl-3-(3,5-tert-butyl-4-hydroxyphenyl)propionate, 4,6-bis(octylthiomethyl)-o-cresol (product is a hindered phenolic antioxidant such as Irganox 1076 manufactured by BASF), a phosphorus-based antioxidant such as tris (2,4-di-tert-butylphenyl) phosphite (Irgafos 176 manufactured by BASF as a product) agents and the like. Each of these stabilizers may be used alone or in combination of two or more. The timing of addition is not particularly limited, and may be either the polymerization process or the devolatilization process. Stabilizers can also be mixed into the product with mechanical devices such as extruders and Banbury mixers.

In the present embodiment, various additives can be added to the styrene resin composition as described above. (B) The total content of the MBS resin (C-1) and the impact-resistant polystyrene (C-2) is not particularly limited, but is preferably 95% by mass or more, more preferably 97% by mass. , more preferably 99% by mass or more.
As a preferred aspect of the present embodiment, the styrenic resin composition preferably contains a higher fatty acid surfactant. Addition of the higher fatty acid-based surfactant provides an anti-blocking effect for the sheet, and moderate addition contributes to a reduction in the torque between pellets during kneading of the resin composition. Therefore, the content of the higher fatty acid-based surfactant is preferably in the range of 0.002 to 0.1 parts by mass with respect to the total amount of the styrene resin composition. The above effect can be obtained, and by making it 0.1 parts by mass or less, it is possible to prevent it from contributing as a gelling agent for the styrene-unsaturated carboxylic acid resin (A).
The higher fatty acid-based surfactant may be added during polymerization of each resin, or additionally kneaded during kneading of the styrene-unsaturated carboxylic acid-based resin (A) and the (meth)acrylic resin (B). good.

Examples of higher fatty acid-based surfactants include, but are not limited to, stearic acid, calcium stearate, calcium stearate, and ethylene bis stearamide, with ethylene bis stearamide being preferred.

[Physical properties of styrene resin composition]
The physical properties of the styrenic resin composition in this embodiment are described below.
<Vicat softening temperature>
In the present embodiment, the Vicat softening temperature of the styrenic resin composition is preferably 105° C. or higher, more preferably 106° C. or higher, even more preferably 107° C. or higher, and still more preferably 108° C. or higher. By setting the Vicat softening temperature to 105°C or higher, a sheet or container that can be applied to heat cooking in a general microwave oven of about 500 W can be obtained. It can withstand heating and cooking in a commercial high-power microwave oven. The Vicat softening temperature can be measured under the conditions of a load of 50 N and a heating rate of 50° C./h in accordance with ISO306.

<Melt mass flow rate>
In the present embodiment, the melt flow rate of the styrenic resin composition at 200° C. is preferably in the range of 0.13 to 2.0 g/10 minutes, more preferably 0.24 to 1.5 g/10 minutes. and more preferably 0.45 to 1.0 g/10 minutes. By setting the melt flow rate to 0.3 g/10 minutes or more, good moldability can be obtained, and by setting it to 2.0 g/10 minutes or less, a resin having excellent strength can be obtained.

<Conjugated diene monomer unit content>
In the present embodiment, the content of conjugated diene monomer units derived from MBS (C-1) and impact-resistant polystyrene (C-2) contained in the styrene resin composition is the entire styrene resin composition. , preferably 1 to 30% by mass, more preferably 3 to 20% by mass, and even more preferably 5 to 15% by mass. In particular, by setting the content of the conjugated diene monomer units in the range of 5 to 15% by mass, a composition having an excellent balance between rigidity and strength can be obtained.

[Extrusion sheet]
Another aspect of the present disclosure provides an extruded sheet formed using the styrenic resin composition of the present invention described above. The extruded sheet can be either non-foamed or foamed. As a method for producing the extruded sheet, a generally known method can be used. As a method for producing a non-foamed extruded sheet, a method using a short-screw or twin-screw extruder equipped with a T-die and a device for taking out the sheet with a uniaxial stretching machine or a biaxial stretching machine can be used. As a method for producing the extruded sheet, a method using an extrusion foam molding machine equipped with a T-die or a circular die can be used.

- Foam extruded sheet -
In the present embodiment, when forming a foamed extruded sheet, substances commonly used as a foaming agent and foaming nucleating agent at the time of extrusion foaming can be used. As the foaming agent, butane, pentane, Freon, carbon dioxide, water, etc. can be used, and butane is preferred. Also, talc or the like can be used as a foam nucleating agent.

In this embodiment, the extruded foam sheet preferably has a thickness of 0.5 mm to 5.0 mm, an apparent density of 50 g/L to 300 g/L, and a basis weight of 80 g/m ² to 300 g/m. ² is preferred. The foam extruded sheet of the present invention may be multi-layered, for example, by further laminating films. The type of film used may be that used for general polystyrene.

-Non-foam extruded sheet-
In this embodiment, the thickness of the non-foamed sheet is preferably, for example, about 0.1 to 1.0 mm from the viewpoint of rigidity and thermoforming cycle. In addition, a uniaxial sheet may be formed only by normal roll stretching at a low magnification, and a biaxially stretched sheet may be formed by stretching about 1.3 to 7 times in the machine direction (MD) with a roll, and then vertically stretching with a tenter. Stretching in the direction (TD) by about 1.3 to 7 times is preferable in terms of strength. Also, the non-foamed sheet may be used in a multi-layered manner with a styrene-based resin such as a polystyrene resin other than the styrene-based resin composition. Further, it may be used in a multi-layered manner with a resin other than a styrene-based resin. Examples of resins other than the styrene-based resins include PET resins and nylon resins.

<Biaxially stretched sheet>
Another aspect of the present disclosure is a biaxially oriented sheet formed using the styrenic resin composition of the present disclosure described above. As a method for producing a biaxially stretched sheet, a commonly known method can be used. The biaxially stretched sheet is produced by stretching in the machine direction (MD) with a roll and then stretching in the vertical direction (TD) with a tenter, or a styrene resin composition molded into a plate is stretched with the composition. It may be produced by sequentially or simultaneously biaxially stretching with a tenter in a state of being heated to about Vicat softening temperature +10 to 40°C.

As the draw ratio of the biaxially stretched sheet of the present embodiment, it is preferable to draw 1.3 to 7.0 times in the MD direction and 1.3 to 7.0 times in the TD direction from the viewpoint of strength.

The average thickness of the biaxially stretched sheet of the present embodiment is preferably 0.1 mm or more, more preferably 0.15 mm or more, and still more preferably 0.2 mm or more, in order to ensure the strength, particularly rigidity, of the sheet and container. be. On the other hand, from the viewpoint of economy, it is preferably 0.7 mm or less, more preferably 0.6 mm or less, and even more preferably 0.5 mm or less.

The biaxially stretched sheet of the present embodiment preferably has a longitudinal and transverse orientation relaxation stress in the range of 0.4 to 1.3 MPa. By adjusting the orientation relaxation stress within this range, the strength of the biaxially oriented sheet molded product can be maintained.

When the biaxially oriented sheet of the present embodiment is used as a food packaging container, a known antifogging agent may be applied to at least one side of the biaxially oriented sheet in order to prevent fogging due to moisture volatilized from the food. Examples of the antifogging agent include nonionic surfactants such as sucrose fatty acid esters and polyglycerin fatty acid esters, and polyether-modified silicone oils.
The method of applying the above antifogging agent to the biaxially oriented sheet of the present embodiment is not particularly limited, and a convenient method includes a method of applying using a roll coater, a knife coater, a gravure roll coater, or the like. Alternatively, spraying, immersion, or the like can be employed. In addition, before coating, the wettability of the surface of the biaxially oriented sheet may be improved by subjecting the surface to corona treatment, ozone treatment, primer treatment, or the like before coating.

[Secondary molded product]
Another aspect of the invention provides a molded article formed using the extruded sheet described above. A biaxially stretched sheet or a multi-layered body containing the same can be formed, for example, by vacuum forming to produce a lid material for a boxed lunch or a container for storing side dishes. In particular, transparent lids for food packaging containers that are compatible with microwave cooking are preferable because the characteristics of the present invention can be fully exhibited.

Next, the present invention will be described in detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. The analysis and evaluation methods for the resins, extruded sheets, etc. in Examples and Comparative Examples are as follows.

[Characteristic evaluation of each resin and resin composition]
(1) Measurement of number-average molecular weight, weight-average molecular weight and Z-average molecular weight (GPC) was used to measure under the following conditions.
Measuring instrument: Tosoh HLC-8220
Separation column: Two TSK gel Super HZM-H manufactured by Tosoh (inner diameter 4.6 mm) connected in series Guard column: TSK guard column Super HZ-H manufactured by Tosoh
Measurement solvent: tetrahydrofuran (THF)
Sample concentration: 5 mg of a sample to be measured was dissolved in 10 mL of solvent and filtered through a 0.45 μm filter.
Injection volume: 10 μL
Measurement temperature: 40°C
Flow rate: 0.35 mL / min Detector: Differential refractometer To create a calibration curve, use 11 types of Tosoh 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) were used. A calibration curve was created using a first-order linear approximation formula.

(2) Measurement of Melt Mass Flow Rate (MFR) Measured under load conditions.

(3) Measurement of Vicat softening temperature The Vicat softening temperature of each resin and styrenic resin composition produced in Examples and Comparative Examples was measured according to ISO306. The load was 50 N, and the heating rate was 50° C./h. Those with a Vicat softening temperature exceeding 105°C are excellent in dimensional stability under the assumed temperature range when sheet moldings and container moldings are microwave-heated. tended not to.

(4) Measurement of content (mass%) of rubber component (C) in styrene resin composition and impact-resistant polystyrene (C-2) In styrene-based resin composition and impact-resistant polystyrene (C-2) The content of the rubber component (C) contained (for example, a rubber particle crosslinked product obtained by graft copolymerization of a styrene resin to polybutadiene rubber particles) is obtained by adding 5 g of a styrene resin composition or impact-resistant polystyrene (C-2) to methyl ethyl ketone. /Methanol = 9/1 (w/w) After dissolving in 50 mL of a solution and dispersing the insoluble rubber component (C), after separating the rubber component (C) and the soluble component by centrifugation or filtration , were weighed, respectively, and obtained by the following formula (3).
Formula (3):
Rubber component (C) content (% by mass) = {mass of rubber component (C) separated as insoluble matter/5 g} x 100

(5) Measurement of content of conjugated diene monomer unit and each monomer unit In the styrenic resin compositions prepared in Examples and Comparative Examples by a calibration curve method using pyrolysis GC/MS under the following conditions The content of the conjugated diene monomer unit and each monomer unit contained in was measured.
Sample preparation: 20 μg of the resin composition prepared in Examples and Comparative Examples was weighed with a precision balance Measurement conditions:
Pyrolysis unit Equipment: Frontier Lab PY-3030D
Heating furnace temperature: 600°C
GC
Equipment: Shimadzu GCMS-GP2020NX
Column: Ultra Alloy-5
(Length 30m, film thickness 0.25μm, diameter 0.250mmφ)
Column temperature: maintained at 50°C for 5 minutes, raised at 10°C/min, raised from 100°C at 7°C/min, and held at 300°C for 10 minutes.
Inlet temperature: 300°C
Detector temperature: 300°C
Split ratio: 1/300
Carrier gas: Helium Detection method: Mass spectrometer (MSD)
When detecting each monomer peak, in order to avoid overlapping of peaks and saturation of peak intensity, pretreatment such as sample dilution ratio, columns to be used, and detection conditions may be adjusted as appropriate.

(6) Method for measuring average particle size of rubber component (C) 1) The average particle size (μm) of rubber-like graft particles (C-2-1) derived from impact-resistant polystyrene (C-2) is 200 particles observed by cross-sectional observation with a transmission electron microscope. For, the following formula (4):
Average particle size = Σ (ni × Di ⁴ ) / Σ (ni × Di ³ )
{In the above formula (4), ni is the number of particles having a particle diameter Di, and Di is the average value of the major and minor diameters of the particles. }
Calculated by

(7) Measurement of haze (cloudiness) of 2 mm plate Each resin composition produced in Examples and Comparative Examples was molded into a 2 mm plate by injection molding, and a simultaneous color and turbidity measuring instrument CH manufactured by Nippon Denshoku Industries Co., Ltd. Total light transmittance and 2 mm plate haze were measured using -300A, and the n3 average was used as the value.

(8) Measurement of 0.7 mm plate surface impact (23 ° C.) Each styrene resin composition is molded into a non-oriented 0.7 mm plate with a hot press, cut into 8 cm × 8 cm, temperature 23 ° C., humidity 50 % for 24 hours, the film impact was measured using a film impact tester (No. 195) manufactured by Toyo Seiki, and the n8 average was taken as the value.

(9) Measurement of 0.7 mm plate surface impact at -30 ° C. The above 0.7 mm plate was cut into 6 cm x 6 cm, cooled in a constant temperature bath set at -30 ° C. for 2 hours or more, and then measured by Toyo Seiki Co., Ltd. Using a DuPont impact tester (No. 451), the falling weight impact strength was quickly measured. The mass of the falling weight is 0.050 kg, the radius of the tip of the impact center is 6.3 mm, and the radius of the impact center cradle is 9.4 mm. ) x (height cm).

(10) Evaluation of heat oil resistance Each resin composition produced in Examples and Comparative Examples was molded into a 2.5 mm plate by injection molding, and the styrene resin composition plate was heated to 90 ° C. ) after immersion for 10 minutes, the haze was measured using a haze meter (NDH-2000) manufactured by Nippon Denshoku Industries Co., Ltd., and the change in haze (Δhaze) before and after immersion was calculated by the following formula. The hot oil resistance was evaluated according to the evaluation criteria.
ΔHaze = post-test haze (%) - pre-test haze (%)
Evaluation criteria ◎... Δ haze is 3% or less 〇 … Δ haze is more than 3% and 7% or less △ … Δ haze is more than 7% and 10% or less × … Δ haze is more than 10%

(11) Measurement of refractive index A test piece obtained by molding each resin composition produced in Examples and Comparative Examples to about 0.1 to 0.2 mm by hot pressing was measured using an Atago Appe digital refractometer. , and the refractive index at 25° C. was measured. When measuring the refractive index of the impact-resistant polystyrene resin (C-2), the rubber component (C) of the styrenic resin composition, and the matrix mixture that does not contain the rubber component (C), an appropriate amount is dissolved in methyl ethyl ketone, and insoluble. The rubber component (C) and the soluble portion (matrix mixture) from which the rubber component (C) was removed were separated by centrifugation, fractionated, dried, and then subjected to refractive index measurement.

[Characteristic evaluation of non-foamed extruded sheet]
(12) Measurement of Heat Resistance of Biaxially Stretched Sheets Biaxially stretched sheets prepared in Examples and Comparative Examples described later were cut into strips of 10 cm × 1.5 cm and placed in an oven set at 110°C for 60 minutes. After that, the deformation of the biaxially stretched sheet was visually observed, and the heat resistance was evaluated as follows from the thermal deformation.
Specifically, for the dimensional change, the amount of change in length of 10 cm before and after thermal deformation was measured according to the following formula (5).
Formula (5): Dimensional change (%) = (length in MD direction of biaxially oriented sheet after being placed in oven for 60 minutes - length in MD direction of biaxially oriented sheet before being placed in oven) / in oven Length in the MD direction of the biaxially stretched sheet before insertion ○: Dimensional change of 1% or less △: Dimensional change of 1% or more and 3% or less ×: Dimensional deformation of 3% or more

(13) Strength measurement of biaxially stretched sheet The biaxially stretched sheet prepared in Examples and Comparative Examples described later was cut into 8 cm × 8 cm, and after conditioning for 24 hours or more at a temperature of 23 ° C. and a humidity of 50%, The film impact was measured using a film impact tester (No. 195) manufactured by Seiki, and the n8 average was used as the value.

(14) Measurement of surface impact of biaxially stretched sheet at −30° C. Biaxially stretched sheets prepared in the examples and comparative examples described later were cut into 6 cm×6 cm and placed in a constant temperature bath set at −30° C. for 2 After cooling for at least 1 hour, the falling weight impact strength was immediately measured using a DuPont impact tester (No. 451) manufactured by Toyo Seiki Co., Ltd. The mass of the falling weight is 0.050 kg, the radius of the tip of the impact center is 6.3 mm, and the radius of the impact center cradle is 9.4 mm. ) x (height cm).
In addition, when a stretched sheet molded product of a styrene resin composition exhibiting a falling weight impact strength at -30 ° C. of 4.5 kg cm or more is molded as a lid material, the lid during refrigerated transportation at about -30 ° C. It showed a tendency to reduce cracking of the material.

(15) Measurement of internal haze (cloudiness) of biaxially stretched sheet Biaxially stretched sheets prepared in Examples and Comparative Examples described later were cut into 3 cm × 5 cm pieces, and the above-mentioned The biaxially stretched sheet was immersed in liquid paraffin, and haze was measured using a haze meter (NDH-2000) manufactured by Nippon Denshoku Industries Co., Ltd., and n3 average was taken as a value.

(16) Appearance determination of non-foamed extruded sheet Using each resin composition prepared in Examples and Comparative Examples, a sheet of the same resin composition is continuously extruded for 30 minutes with a 30 mmφ short-axis sheet extruder, and then the thickness Five sheets of 10 cm × 20 cm in size are cut out from a sheet of 0.3 mm, and the number of unmelted foreign substances having an average diameter of (major axis + minor axis)/2 of 0.3 mm or more on the surface of the five sheets was counted and the appearance was judged by the following method.
○: The number of unmelted objects is 2 or less △: The number of unmelted objects is 3 to 9 ×: The number of unmelted objects is 10 or more

[Characteristics evaluation of molded product formed by secondary molding of biaxially stretched sheet]
The biaxially stretched sheets prepared in Examples and Comparative Examples were formed into a lid-shaped body of 160 mm long × 140 mm wide × 40 mm high by using a hot plate molding machine at a hot plate temperature of 145 ° C. and a heating time of 2.0 seconds. was prepared and subjected to the following evaluations.
(17) Heat resistant oil resistance during heating in a microwave oven MCT oil was applied to the center of the lid of the lid-like body in a circle with a diameter of about 5 mm, moistened with a mist sprayer, and covered with a polyvinylidene chloride film so that the moisture would not evaporate. Then, after heating for 60 seconds in a 750 W microwave oven, the state of the MCT oil adhered portion was visually evaluated.
〇: No change △: Whitening, no tearing ×: Whitening, the applied part was torn

(18) Transparency (after molding)
The haze of the lid-shaped body was measured using a cloudiness meter (NDH-2000) manufactured by Nippon Denshoku Industries Co., Ltd., and the n3 average was measured and evaluated according to the following criteria.
○: Haze 2.0% or less △: Haze over 2.0% to 5.0% or less ×: Haze over 5.0%

(19) Lid-shaped molding strength (23°C)
A test piece measuring 80 mm in length and 80 mm in width was cut out from the center of the lid of the lid-shaped body, and 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, and evaluated from the following viewpoints. bottom.
◯: 6.0 kg·cm or more △: 3.0 kg·cm or more and less than 6.0 kg·cm ×: Less than 3.0 kg·cm The result was that the 6.0 kg·cm container did not crack during transportation.

(20) Lid-shaped molding strength (-30°C)
In order to evaluate the low-temperature impact resistance, the strength of the lid-like body at -30°C was evaluated. The lid-shaped body prepared by the method described in the above column (19) is turned upside down, 100 g of pure water is poured, and the water is frozen in a constant temperature bath at -30 ° C. for 3 hours or more. It was evaluated whether the lid-shaped body would break when dropped from a height of . Among the 10 samples, the number of points where fracture was observed was tabulated and evaluated from the following viewpoints.
○: 1 out of 10 cracked △: 1 to 3 out of 10 cracked ×: 4 or more out of 10 cracked

[Preparation of each resin and production example of styrenic resin composition]
The preparation of each resin and the specific production method of the styrenic resin composition are described below.

<Production example of styrene-unsaturated carboxylic acid resin (A)>
-Preparation of Resin A-1-
Styrene 65.5 parts by mass, methyl methacrylate 3.3 parts by mass, methacrylic acid 5.8 parts by mass, ethylbenzene 22.9 parts by mass, 2-ethyl-1-hexanol 2.5 parts by mass, fine oxo manufactured by Nissan Chemical Co., Ltd. A polymerization raw material composition liquid consisting of 1.2 parts by mass of Cole 180 and 0.027 parts by mass of 1,1-bis(t-butylperoxy)cyclohexane was added at a rate of 0.8 liter/hour to a volume of 3.6 liters. and then continuously fed to a devolatilization device connected to a single-screw extruder for removing volatile components such as unreacted monomers and polymerization solvent. The polymerization temperature in the fully mixed reactor was 130°C. The single-screw extruder was set at a temperature of 210 to 230° C. and a pressure of 10 torr to devolatilize volatile components such as unreacted monomers and polymerization solvent. The devolatilized volatile components were condensed in a condenser through which a -5° C. refrigerant was passed, and recovered as an unreacted liquid, and the styrene resin was recovered as resin pellets. Table 1 below shows the physical properties of Resin A-1 obtained by the above analytical method.

-Preparation of Resin A-2--
Resin except that methyl methacrylate is not used, 1-octanol is used instead of 2-ethyl-1-hexal, and Emulgen 109 manufactured by Kao Corporation is used instead of Fine Oxocol 180 manufactured by Nissan Chemical Co., Ltd. Resin A-2 was prepared in the same manner as A-1. Table 1 shows the composition and physical properties of Resin A-2.

-Preparation of Resin A-3-
Using only styrene as a monomer, Resin A-3 was prepared as a styrene homopolymer in the same manner as above. Table 1 shows the composition and physical properties of Resin A-3.

<Production example of (meth)acrylic resin (B)>
-Preparation of resin B-1-
2 kg of water, 65 g of tribasic calcium phosphate, 39 g of calcium carbonate, and 0.39 g of sodium lauryl sulfate were put into a 5 L container equipped with a stirrer, and mixed and stirred to prepare a suspension. Next, 26 kg of water was put into a 60 L reactor, and the temperature was raised to 80° C. to prepare for suspension polymerization. After confirming that the temperature reached 80° C. and became a constant temperature, 9.81 kg of methyl methacrylate, 0.20 kg of methyl acrylate, 0.99 g of lauroyloperoxide, 4.93 g of n-octyl mercaptan, and 4.93 g of n-octyl mercaptan were added as polymerization raw materials. The suspending agent was added. Thereafter, suspension polymerization was carried out while maintaining the temperature at about 80° C. After observing an 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, after cooling to 50° C., 20% by mass sulfuric acid was added to dissolve the suspending agent. Then, the polymerization reaction solution was taken out from the 60 L reactor, passed through a sieve with a sieve opening of 1.7 mm to remove large agglomerates, and then separated into a water layer and a solid matter with a Buchner funnel to obtain a bead-like polymer. . The bead-shaped polymer is washed on a Buchner funnel five times with about 20 L of distilled water, dehydrated repeatedly, dried, pelletized using a single-screw extruder, and pelletized to obtain Resin B-1. prepared. Table 2 shows the composition and physical properties of Resin B-1.

-Preparation of resins B-2 and B-3-
Resins B-2 and B-3 were prepared in the same manner as the resin B-1 by adjusting the feed amount of each monomer and the polymerization conditions. Table 2 shows the compositions and physical properties of Resin B-2 and Resin B-3 thus obtained.

-Preparation of Resin B-4-
A separable flask (capacity 5 L) equipped with a thermometer, a nitrogen inlet tube, a condenser and a stirrer was charged with 300 parts by mass of ion-exchanged water as a dispersion medium, 1.1 parts by mass of sodium dodecylbenzenesulfonate as an emulsifier, and a chain transfer agent. 0.01 parts by mass of n-octyl mercaptan as a monomer, 88 parts by mass of methyl methacrylate and 12 parts by mass of butyl acrylate as monomers were added. The atmosphere in the flask was replaced with nitrogen by passing a nitrogen stream through the separable flask. Next, the internal temperature was raised to 60° C., and 0.15 parts by mass of potassium persulfate and 5 parts by mass of deionized water were added. After that, heating and stirring was continued for 2 hours to complete the polymerization, and an acrylic resin latex was obtained. After cooling the acrylic resin latex to 25° C., it was added dropwise to 500 parts by mass of hot water at 70° C. containing 5 parts by mass of calcium acetate, and then heated to 90° C. to cause coagulation. After separating and washing the coagulate, it was dried at 60° C. for 12 hours to obtain Resin B-4. Table 2 shows the composition and physical properties of Resin B-4.

<Production example of MBS resin (C-1)>
-Preparation of MBS-1-
In a separable flask equipped with a stirrer, 200 parts by mass of pure water, 0.002 parts by mass of ethylenediaminetetraacetic acid disodium salt, 0.0012 parts by mass of ferrous sulfate, 0.008 parts by mass of ethylenediaminetetraacetic acid disodium salt and After charging 0.03 parts by mass of sodium polyoxyethylene alkyl ether phosphate and deoxidizing, 100 parts by mass of butadiene, 0.05 parts by mass of sodium formaldehyde sulfoxylate and 0.2 parts by mass of p-menthane hydroperoxide are added. After that, 1.4 parts by mass of sodium polyoxyethylene alkyl ether phosphate was added dropwise over 6 hours to prepare a reaction solution. Then, the pH of the reaction solution was kept in the range of 6.5 to 7.5 at 50° C. for 124 hours to obtain a conjugated diene rubber latex having a conversion rate of 98% by mass and a volume average particle size of 0.18 μm. .
Subsequently, monomers of 12 parts by mass of methyl methacrylate and 48 parts by mass of styrene were added over 1 hour while the conjugated diene rubber latex (solid content: about 71 parts) was kept at 60°C. Further, while the pH of the reaction solution is within the range of 6.5 to 7.5 and the temperature of the reaction solution is maintained at about 60° C., t-butyl hydroperoxide is added to 0 at the same time as the monomer is added. 0.09 parts by weight and 0.1 parts by weight of sodium formaldehyde sulfoxylate were started and added completely over 2 hours. The resulting reaction solution was held at about 60° C. for 1 hour to obtain resin MBS-1, which is a graft copolymer having a volume average particle size of 200 nm. Table 3 shows the composition and physical properties of the resin MBS-1.

-Preparation of MBS-2, MBS-3, and MBS-4-
MBS-2 to MBS-4 were prepared in the same manner as resin MBS-1 by adjusting the feed amount of each monomer and the polymerization conditions. Table 3 shows the compositions and physical properties of MBS-2 to MBS-4 obtained.

<Production example of impact-resistant polystyrene (C-2)>
<<Preparation of Resin HI-1>>
Using a polymerization apparatus consisting of three laminar flow reactors (1.5 liters) equipped with stirrers connected in series followed by a two-stage vented extruder, high-impact polystyrene (resin HI-1) was prepared. manufactured. 71.3 parts by mass of styrene, 7.6 parts by mass of butyl acrylate, 10.5 parts by mass of ethylbenzene, and Asaprene 625A manufactured by Asahi Kasei Co., Ltd., a styrene-butadiene copolymer as the rubber component (C), were placed in a raw material tank equipped with a stirrer. 5 parts by mass and 0.02 parts by mass of 1,1-bis(t-butylperoxy)cyclohexane were charged, and after dissolving the rubber component (C) with a stirrer, this raw material solution was added to the reactor at 0.75 liter/hr. and the temperature of the first stage reactor is 110 to 120°C, the temperature of the second stage reactor is 120 to 130°C, and the temperature of the third stage reactor is 140 to 150°C. rice field. The temperature of the extruder was 210 to 240° C., the degree of vacuum was 3 kPa, and the total solid content in the polymerization solution discharged from the final reactor was 70.1 mass %. The average particle size of the rubber component (C) was controlled by adjusting the rotational speed of the stirrer of the first stage laminar flow reactor to 120 rpm. Table 4 shows the composition and properties of the obtained impact-resistant polystyrene HI-1 (hereinafter referred to as resin HI-1).

<<Preparation of Resin HI-2>>
Using styrene, methyl methacrylate, and acrylic acid (n-butyl) as monomers, and using Asaprene 625A, a styrene-butadiene copolymer manufactured by Asahi Kasei Co., Ltd., as the rubber component (C), styrene-methacrylic acid was prepared in the same manner as above. A resin HI-2 having a methyl-(n-butyl)acrylate copolymer as a matrix component was prepared. Table 4 shows the composition and properties of the obtained resin HI-2.

<<Preparation of Resin HI-3>>
Resin HI-3 having a styrene homopolymer as a polymer matrix component was prepared in the same manner as described above, using only styrene as a monomer and Diene 35AE of polybutadiene manufactured by Asahi Kasei Co., Ltd. as a rubber component (C). Table 4 shows the composition and properties of the resulting resin HI-3.

In this embodiment, the following methyl methacrylate-butyl acrylate block copolymer was used.
Methyl methacrylate-butyl acrylate block copolymer manufactured by Kuraray Co., Ltd.: LA4285

<Production example of styrene-based resin composition>
The detailed manufacturing method of the styrene-based resin composition is shown below.
-Example 1-
69.4 parts by mass of resin A-1 listed in Table 1 as styrene-unsaturated carboxylic acid resin (A), and 19.6 parts by mass of resin B-1 listed in Table 2 as (meth)acrylic resin (B) 10 parts by mass of MBS-1 listed in Table 3 as MBS resin (C-1) was dry blended, kneaded and extruded using a twin-screw extruder TEM26SS manufactured by Shibaura Machine Co., Ltd., pelletized, and styrene-based as a pellet-shaped resin. A resin composition was obtained. 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 250-260°C.
Next, the obtained pellet-shaped styrene-based resin composition was processed into a plate of 10 cm x 10 cm x 1.2 mm by press molding. The plate was set to a distance between chucks of 85 mm with a batch biaxial stretching machine EX6-S1 manufactured by Toyo Seiki Co., Ltd. After preheating for 10 minutes at the Vicat softening temperature of the styrene resin composition + 20 ° C., the X axis was stretched at 250 mm / min. It was stretched at a magnification of 2.4 and a Y-axis magnification of 2.4 to obtain a biaxially stretched sheet with a thickness of about 0.2 mm. Table 5 shows the evaluation results of the resulting composition and biaxially oriented sheet, and the evaluation results of the molded article.

-Examples 2 to 17-
A resin composition and a biaxially oriented sheet were obtained in the same manner as in Example 1, except that the formulation was changed as shown in Table 5 below. Table 5 shows the evaluation results of the composition and the biaxially oriented sheet, and the evaluation results of the molded article.

-Comparative Examples 1 to 6-
A resin composition and a biaxially stretched sheet were obtained in the same manner as in Example 1, except that the formulation was changed as shown in Table 6 below. Table 5 shows the evaluation results of the composition and the biaxially oriented sheet, and the evaluation results of the molded article.

The styrenic resin composition obtained by the present invention is excellent in low-temperature impact resistance, transparency, heat resistance, hot oil resistance, rigidity and appearance. Therefore, the styrene-based resin composition of the present invention can be used for extrusion molding, non-foamed sheets or foamed sheets, food packaging containers using them, or molded articles by injection molding (electrical product parts, toys, daily necessities, various industrial parts), etc. It can be used in a wide range of applications, and is particularly useful as a packaging material for refrigerated transportation, and plays a major role in industry.

Claims (16)

Styrene-unsaturated carboxylic acid resin (A), (meth)acrylic resin (B) and rubber component (C),
(content of the styrene-unsaturated carboxylic acid resin (A))/(content of the (meth)acrylic resin (B)) is in the range of 1 to 4;
A styrenic resin composition containing 1 to 45% by mass of the rubber component (C) relative to the total amount (100% by mass) of the styrenic resin composition. The styrene-unsaturated carboxylic acid resin (A) comprises a styrene monomer unit (a1), a (meth)acrylic acid monomer unit (a2-1) and a (meth)acrylic ester monomer unit ( The styrenic resin composition according to claim 1, which is a copolymer (A-1) having a2-2). 3. The styrene-based resin composition according to claim 1, wherein the styrene-unsaturated carboxylic acid-based resin (A) is contained in an amount of 45 to 75% by mass based on the entire styrene resin composition. The styrene resin composition according to any one of claims 1 to 3, wherein the (meth)acrylic resin (B) has a weight average molecular weight (Mw) of 70,000 to 900,000. The styrenic resin composition according to any one of claims 1 to 4, which has a Vicat softening temperature of 105°C or higher. 6. The method according to any one of claims 1 to 5, further containing 0.5 to 30% by mass of impact-resistant polystyrene (C-2) with respect to the total amount (100% by mass) of the styrene resin composition. A styrenic resin composition. The rubber component (C) comprises a (meth)acrylic-butadiene-styrene copolymer (C-1) having a styrene-based monomer unit (c1), a methyl methacrylate monomer unit and a butadiene unit, and an impact resistant 7. The one or more selected from the group consisting of rubber-like graft particles (C-2-1) derived from polystyrene (C-2), according to any one of claims 1 to 6. A styrenic resin composition. The styrene resin according to claim 7, wherein the rubber component (C) is the (meth)acrylic-butadiene-styrene copolymer (C-1) and the rubber-like graft particles (C-2-1). Composition. Difference in refractive index between the rubber component (C) and the matrix mixture in which the mixing ratio of the styrene-unsaturated carboxylic acid resin (A) and the (meth)acrylic resin (B) is within the range of the weight ratio is in the range of 0 to 0.01, the styrenic resin composition according to any one of claims 1 to 8. The styrenic resin composition according to any one of claims 1 to 9, wherein the rubber component (C) has a refractive index in the range of 1.530 to 1.550. The styrenic resin composition according to any one of claims 1 to 10, wherein the rubber component (C) is rubber crosslinked particles. The styrenic resin composition according to any one of claims 1 to 11, wherein the rubber component (C) is contained in an amount of 5 to 35% by mass with respect to the total amount (100% by mass) of the styrenic resin composition. The styrene-unsaturated carboxylic acid resin (A) contains 40 to 97% by mass of styrene monomer units (a1), 2 to 30% by mass of methacrylic acid monomer units, and 1 to 1 methyl methacrylate monomer units. 13. The styrenic resin composition according to any one of claims 1 to 12, which is a copolymer having 30% by mass. A molded article obtained by molding the styrenic resin composition according to any one of claims 1 to 13. An extruded sheet having the styrenic resin composition according to any one of claims 1 to 13. A food packaging container for a microwave oven, which is obtained by processing the molded article according to claim 14.