JP2024018942A - Styrenic resin composition, foam extrusion sheet, and container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a styrenic resin composition which is excellent in moldability without lowering heat resistance and impact resistance, an extrusion sheet using the same, and a container which is obtained by secondary molding of the extrusion sheet.

SOLUTION: A styrenic resin composition contains 50-98 mass% of a styrene-unsaturated carboxylic acid-based resin (A) having a styrenic monomer unit (a1) and an unsaturated carboxylic acid-based monomer unit (a2), and 2-50 mass% of a (meth)acrylic resin (B) having an unsaturated carboxylic acid-based monomer unit (b1), wherein elongation viscosity (MPa s) of the styrenic resin composition at a temperature of 160°C, strain viscosity of 1.0/s and a Henky strain of 0.5 is 0.6 MPa s or less.

SELECTED DRAWING: None

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present disclosure relates to a styrenic resin composition, a foamed extruded sheet molded using the styrenic resin composition, and a food container formed by second-molding the foamed extruded sheet.

Styrene-unsaturated carboxylic acid resins, such as styrene-methacrylic acid copolymer resins, have excellent heat resistance, transparency, rigidity, and appearance, and are inexpensive, so they are used as packaging materials for food containers such as lunch boxes and side dishes. It is widely used in foam boards for insulation in homes, diffuser panels for LCD televisions containing a diffusing agent, etc. Particularly in recent years, with the spread of high-power microwave ovens used for commercial purposes such as convenience stores, containers that can withstand the temperature of cooking in high-power microwave ovens and materials used for sealing or covering the containers have been developed. A styrene-unsaturated carboxylic acid resin is used. However, the problem is that its strength and moldability are lower than that of general-purpose styrene resins.
For example, Patent Document 1 describes a technique for improving mechanical strength while maintaining practical heat resistance using a mixture of a styrene-methacrylic acid copolymer and a polyethylene resin.

Japanese Patent Application Publication No. 2014-80562

In the technique of Patent Document 1 mentioned above, although mechanical strength has been studied, moldability and container appearance have not been studied. In addition, conventional styrene-unsaturated carboxylic acid copolymer resins have a tendency to crack during foam sheet molding and container molding due to their high melt viscosity and resin brittleness, so mechanical strength and moldability are poor. There is a need for both.
Therefore, an object of the present disclosure is to provide a styrenic resin composition that has excellent heat resistance, mechanical strength, and moldability. Another aspect of the present disclosure provides a foamed extruded sheet containing a molded styrenic resin composition having excellent heat resistance, mechanical strength, and moldability, and a food container formed by second-molding the foamed extruded sheet. The purpose is to

As a result of intensively studying the above-mentioned problems and conducting repeated experiments, the present inventors have discovered a styrene-based resin that combines a specific styrene-unsaturated carboxylic acid resin (A) and a specific (meth)acrylic resin (B). The inventors have discovered that the above problem can be solved by reducing the elongational viscosity of the composition to a certain value or less, and have completed the present invention.
[1] The present disclosure includes 50 to 98% by mass of a styrene-unsaturated carboxylic acid resin (A) having a styrene monomer unit (a1) and an unsaturated carboxylic acid monomer unit (a2), and A styrenic resin composition containing a (meth)acrylic resin (B) having a saturated carboxylic acid monomer unit (b1) at a temperature of 160° C. and a strain rate of 1.0 to 50% by mass. The styrenic resin composition has an elongational viscosity (MPa·s) of 0.6 MPa·s or less at 0/s and Henky strain of 0.5.
[2] The styrenic resin composition according to [1] above, wherein the (meth)acrylic resin (B) has an ethylene monomer unit.
[3] The melt tension (gf) of the styrene-based resin composition at a temperature of 220°C and a take-up speed of 3.1 m/min is compared to the melt tension (gf) of the styrene-based resin composition at a temperature of 160°C, a strain rate of 1.0/s, and a Henky strain of 0.5. The styrenic resin composition according to [1] or [2] above, wherein the value divided by the elongational viscosity (MPa·s) of the resin composition is 16 or more.

[4] A high melt tension, low viscosity component that has the effect of increasing the melt tension of the styrenic resin composition by 5% or more and/or reducing the elongational viscosity of the styrenic resin composition by 5% or more. The styrenic resin composition according to any one of [1] to [3] above, further comprising:

[5] The unsaturated carboxylic acid monomer unit (a2) consists of a (meth)acrylic acid monomer unit (a2-1) and a (meth)acrylic acid ester monomer unit (a2-2). The styrenic resin composition according to any one of [1] to [4] above, which contains one or more selected from the group consisting of:

[6] The styrene-unsaturated carboxylic acid resin (A) comprises the styrene monomer unit (a1), the (meth)acrylic acid monomer unit (a2-1), and the (meth)acrylic acid having an ester monomer unit (a2-2) as an essential component,
Containing 2 to 30% by mass of the (meth)acrylic acid monomer unit (a2-1) based on the entire styrene-unsaturated carboxylic acid resin (A), and the (meth)acrylic acid ester monomer The styrenic resin composition according to any one of [1] to [5] above, containing 1 to 20% by mass of the unit (a2-2).

[7] The content of all (meth)acrylic acid ester monomer units contained in the styrenic resin composition is 10 to 50% by mass with respect to the total amount of the styrenic resin composition [ 1] to [6].

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

[9] The styrenic resin composition according to any one of [1] to [8] above, wherein the (meth)acrylic resin (B) has four or more inflection points on the differential molecular weight distribution curve. thing.

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

[11] The composition according to any one of [1] to [10] above, further containing 0.05 to 3.0% by mass of inorganic particles (H) based on the total amount of the styrenic resin composition. Styrenic resin composition.

[12] One aspect of this embodiment is a molded styrenic resin composition according to any one of [1] to [11] above, which has a closed cell ratio of 80% or more, and It is an extruded foam sheet with an average thickness in the range of 0.5 to 3.0 mm.

[13] One aspect of this embodiment is a foam container formed by secondary molding the foam extrusion sheet described in [12] above.

According to the present disclosure, it is an object of the present disclosure to provide a styrenic resin composition that is used for a molded article having excellent heat resistance, mechanical strength, and moldability.
According to the present disclosure, it is possible to provide an extruded foam sheet and a microwaveable foam container that have excellent heat resistance, mechanical strength, and moldability.

Hereinafter, a mode for carrying out the present invention (hereinafter referred to as "this embodiment") will be described in detail. Note that the present invention is not limited to the following embodiments, and can be implemented with various modifications within the scope of the gist.
[Styrenic resin composition]
The styrenic resin composition (hereinafter sometimes simply referred to as a resin composition) in this embodiment is a styrene resin composition having a styrene monomer unit (a1) and an unsaturated carboxylic acid monomer unit (a2). It contains an unsaturated carboxylic acid resin (A) and a (meth)acrylic resin (B) having an unsaturated carboxylic acid monomer unit (b1), and the total amount of the styrene resin composition (100% by mass). ), the content of the styrene-unsaturated carboxylic acid resin (A) is 50 to 98% by mass, and the content of the (meth)acrylic resin (B) is more than 0% by mass and 50% by mass. It is as follows. The styrene resin composition has an elongational viscosity (EV described below) of 0.6 or less. Further, the value of melt tension (MT described below)/elongational viscosity (EV described below) of the styrenic resin composition is preferably 16 or more.
As a result, a resin that is easy to stretch and hard to break when melted can be obtained, and a foamed extruded sheet with high moldability can be obtained.
In this specification, the elongational viscosity (MPa·s) of the styrenic resin composition at a temperature of 160°C, a strain rate of 1.0/s, and a Henky strain of 0.5 is also referred to as "EV", and a temperature of 220°C, The melt tension (gf) of the styrenic resin composition at a take-up speed of 3.1 m/min is also referred to as "MT".
The EV of the styrenic resin composition in this embodiment is 0.6 MPa·s or less, preferably 0.59 MPa·s or less, more preferably 0.58 MPa·s or less, still more preferably 0.57 MPa·s Below, it is still more preferably 0.56 MPa·s or less, even more preferably 0.55 MPa·s or less, and most preferably 0.53 MPa·s or less. The lower limit is preferably 0.15 MPa·s or more, more preferably 0.10 MPa·s or more, even more preferably 0.15 MPa·s or more, and most preferably 0.20 MPa·s or more. By particularly controlling the EV of the styrenic resin composition of the present embodiment in the range of 0.15 to 0.6 MPa·s, it is possible to obtain a styrenic resin composition in which the resin is more easily extensible when melted.
The MT/EV value of the styrenic resin composition in this embodiment is preferably 16 to 400. When MT/EV is 16 or more, the molten resin becomes difficult to break, and a foamed extruded sheet with higher moldability can be obtained. On the other hand, when the value of MT/EV is set to 400 or less, the melt tension falls within a suitable range, and excellent moldability is exhibited. On the other hand, if the EV is more than 0.6 MPa·s and the value of MT/EV is more than 400, the melt tension will become excessively high, leading to deterioration of moldability. Therefore, by setting the MT/EV in the range of 18 to 70, it is possible to obtain a styrenic resin composition with particularly excellent moldability, as well as foamed extruded sheets and molded products formed from the same.
Hereinafter, each component and physical properties of the styrenic resin composition of the present disclosure will be explained in detail.

"Styrene-unsaturated carboxylic acid resin (A)"
The styrene-unsaturated carboxylic acid resin (A) in this embodiment is a copolymer resin (hereinafter referred to as It is also simply referred to as resin (A)) and contributes to improving the heat resistance of the entire styrenic resin composition. The unsaturated carboxylic acid monomer unit (a2) is selected from the group consisting of (meth)acrylic acid monomer unit (a2-1) and (meth)acrylic acid ester monomer (a2-2). It is preferable that it is one or more types of monomer units.
In addition, the styrene-unsaturated carboxylic acid resin (A) may contain styrene monomer units (a1) and unsaturated carboxylic acid monomer units (a2) (for example, (meth)acrylic acid monomer units), if necessary. One or more monomer units selected from the group consisting of unit (a2-1) and (meth)acrylic acid ester monomer (a2-2), other monomers other than the essential component It may further contain a unit (a3).
The content of the styrene-unsaturated carboxylic acid resin (A) is 50 to 98% by mass, preferably 53 to 97% by mass, more preferably It is 55 to 96% by weight, more preferably 60 to 95% by weight. By setting the content of the styrene-unsaturated carboxylic acid resin (A) to 50% by mass or more, a sufficient effect of imparting heat resistance can be obtained, and by setting the content to 98% by mass or less, the below-mentioned (meth) The effect of improving mechanical strength by the acrylic resin (B) can be sufficiently obtained.
The styrene-unsaturated carboxylic acid resin (A) of this embodiment is preferably a random copolymer or an alternating copolymer.

<Styrenic monomer (a1)>
In the styrene-unsaturated carboxylic acid resin (A) of the present embodiment, the content of the styrene monomer unit (a1) is 60 to 60 with respect to the total amount of the styrene-unsaturated carboxylic acid resin (A). It is 98% by weight, preferably 70 to 97% by weight, more preferably 80 to 96% by weight, even more preferably 82 to 95% by weight. If the content of the styrene monomer unit (a1) is less than 60% by mass, fluidity will decrease, and if it is more than 98% by mass, the content of the unsaturated carboxylic acid monomer (a2) (especially ( It becomes difficult to contain the desired amount of meth)acrylic acid monomer unit (a2-1), and in particular, the effect of improving heat resistance by the (meth)acrylic acid monomer unit (a2-1) cannot be sufficiently obtained. .
Further, in the styrenic resin composition of the present embodiment, the styrenic monomer unit (a1) is preferably contained in an amount of 45 to 85% by mass, preferably 48 to 85% by mass based on the total amount of the styrenic resin composition. It is 82% by weight, more preferably 52-79% by weight, even more preferably 56-77% by weight. When the content of the styrene monomer (a1) in the entire composition is within the above range, a sufficient effect of improving heat resistance can be obtained.

In this embodiment, the styrenic monomer (a1) is not particularly limited, but examples include styrene, α-methylstyrene, β-methylstyrene, paramethylstyrene, orthomethylstyrene, metamethylstyrene, chlorostyrene, Examples include bromostyrene. Particularly from an industrial standpoint, styrene and α-methylstyrene are preferred, and styrene is more preferred. As the styrenic monomer (a1), these can be used alone or in combination of two or more.
In addition, the "styrenic monomer unit (a1)" in this specification means a repeating unit constituting a polymer in which the styrenic monomer (a1) is polymerized, and the styrenic monomer (a1) ) is a repeating unit (or structural unit) in which a carbon-carbon double bond in the styrenic monomer (a1) becomes a single bond (-CC-) through a polymerization reaction or a crosslinking reaction. Moreover, other monomer units in this specification have the same meaning.

<Unsaturated carboxylic acid monomer (a2)>
In the styrene-unsaturated carboxylic acid resin (A) of this embodiment, the unsaturated carboxylic acid monomer unit (a2) has heat resistance, oil resistance, and the following (meth)acrylic resin (B). plays a role in improving the compatibility of With respect to the total amount of the styrene-unsaturated carboxylic acid resin (A), the content of the unsaturated carboxylic acid monomer unit (a2) is 2 to 40% by mass, preferably 3 to 35% by mass, The range is more preferably 5 to 30% by weight, even more preferably 8 to 25% by weight, and most preferably 10 to 20% by weight. If the content of the unsaturated carboxylic acid monomer unit (a2) is less than 2% by mass, the effect of improving heat resistance is insufficient. In addition, if the content of the unsaturated carboxylic acid monomer unit (a2) exceeds 40% by mass, there may be problems such as a decrease in processability due to an increase in resin viscosity and the generation of air bubbles during molding due to an increase in water absorption. This is not desirable. In particular, by setting the content of the unsaturated carboxylic acid monomer unit (a2) to 10 to 20% by mass, good compatibility with the (meth)acrylic resin (B) can be obtained, resulting in excellent transparency. A composition can be obtained.
In addition, the unsaturated carboxylic acid monomer unit (a2) in this embodiment includes an unsaturated carboxylic acid and its ester, and specifically, the (meth)acrylic acid monomer unit (a2-1 ) and (meth)acrylic acid ester monomer (a2-2).

<<(meth)acrylic acid monomer (a2-1)>>
In the styrene-unsaturated carboxylic acid resin (A) of the present embodiment, the (meth)acrylic acid monomer unit (a2-1) has oil resistance and compatibility with the (meth)acrylic resin (B) described below. Plays a role in improving compatibility. When the styrene-unsaturated carboxylic acid resin (A) of this embodiment contains the (meth)acrylic acid monomer unit (a2-1), the total amount of the styrene-unsaturated carboxylic acid resin (A) On the other hand, the content of the (meth)acrylic acid monomer unit (a2-1) is preferably 2 to 40% by mass, more preferably 3 to 35% by mass, more preferably 5 to 30% by mass, and even more Preferably it ranges from 8 to 25% by weight, most preferably from 10 to 20% by weight. In another embodiment, the content of the (meth)acrylic acid monomer unit (a2-1) is preferably 3 to 20% by mass, more preferably 4 to 17% by mass, even more preferably 8 to 14% by mass. Mass%. If the content of the (meth)acrylic acid monomer unit (a2-1) is less than 2% by mass, the effect of improving heat resistance is insufficient. In addition, if the content of (meth)acrylic acid monomer unit (a2-1) exceeds 40% by mass, processability may decrease due to increased resin viscosity, air bubbles may occur during molding due to increased water absorption, and during manufacturing. This is not preferable because the viscosity becomes too high. The effect of improving heat resistance can be obtained by setting the content of the (meth)acrylic acid monomer unit (a2-1) to 2% by mass or more, and by setting the content to 40% by mass or less. This can prevent the viscosity from increasing too much. In particular, by setting the content of the (meth)acrylic acid monomer unit (a2-1) to 8 to 25% by mass, good compatibility with the (meth)acrylic resin (B) can be obtained, and (meth) The effect of improving the strength and melt tension during kneading with the acrylic resin (B) can be efficiently obtained.

In this embodiment, the (meth)acrylic acid monomer unit (a2-1) plays a role in improving heat resistance. Examples of the (meth)acrylic acid monomer (a2-1) include acrylic acid and methacrylic acid. Particularly from an industrial standpoint, the (meth)acrylic acid monomer unit (a2-1) 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 has a large effect of improving heat resistance.

<<(meth)acrylic acid ester monomer (a2-2)>>
In this embodiment, the styrene-unsaturated carboxylic acid resin (A) may further contain a (meth)acrylic acid ester monomer (a2-2). The (meth)acrylic acid ester monomer (a2-2) plays a role in improving oil resistance and strength. The (meth)acrylic acid ester monomer (a2-2) has the following general formula (1):
(In the above general formula (1), R ¹ represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and R
² represents an ester substituent, specifically an alkyl group having 1 to 12 carbon atoms. ) is preferably represented.
In this 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 is 8 or less, more preferably 4 or less. If the number of carbon atoms in the ester substituent exceeds 10, the heat resistance will be significantly reduced, which is not preferable.

Examples of the (meth)acrylic acid ester monomer (a2-2) in this embodiment include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, and butyl (meth)acrylate. , cyclohexyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, decyl (meth)acrylate, and the like. These can be used alone or in combination. As the (meth)acrylic acid ester monomer (a2-2), methyl (meth)acrylate or butyl (meth)acrylate is preferable from the viewpoint of industrial availability, and methacrylate from the viewpoint of suppressing a decrease in heat resistance. Particularly preferred is methyl acid.
In this embodiment, when the styrene-unsaturated carboxylic acid resin (A) of this embodiment contains the (meth)acrylic acid ester monomer unit (a2-2), the styrene-unsaturated carboxylic acid resin ( The content of the (meth)acrylic acid ester monomer unit (a2-2) relative to the total amount of A) is, for example, preferably 2 to 40% by mass, more preferably 3 to 32% by mass. %, more preferably 3 to 20% by weight, even more preferably 3 to 17% by weight, even more preferably 3 to 12% by weight, even more preferably 4 to 10% by weight. By setting the content of the (meth)acrylic acid ester monomer unit (a2-2) to 2 to 40% by mass, good compatibility with the (meth)acrylic resin (B) can be obtained, and (meth) The effect of improving the strength and melt tension during kneading with the acrylic resin (B) can be efficiently obtained.

<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 may be a multicomponent polymer. That is, the styrene-unsaturated carboxylic acid resin (A) of the present embodiment is a binary copolymer of a styrene monomer unit (a1) and a (meth)acrylic acid monomer unit (a2-1). In addition, a ternary copolymer in which a styrene monomer (a1), a (meth)acrylic acid monomer (a2-1), and a (meth)acrylic acid ester monomer (a2-2) are copolymerized It may be a terpolymer containing a combination or a styrene monomer unit (a1) and two types of (meth)acrylic acid monomer units (a2-1). This further provides the effects of improving compatibility with the (meth)acrylic resin (B), improving surface hardness, or improving mechanical strength.
In particular, when emphasis is placed on improving heat resistance and surface hardness, the styrene-unsaturated carboxylic acid resin (A) preferably contains (meth)acrylic acid monomer units (a2-1). Furthermore, particularly when emphasis is placed on improving the appearance and mechanical strength, the styrene-unsaturated carboxylic acid resin (A) preferably contains (meth)acrylic acid ester monomer units (a2-2). Furthermore, when emphasizing improved compatibility with the (meth)acrylic resin (B) and high transparency of the mixture with the resin (B), the styrene-unsaturated carboxylic acid resin (A) is A ternary copolymer in which a styrene monomer unit (a1), a (meth)acrylic acid monomer unit (a2-1), and a (meth)acrylic acid ester monomer unit (a2-2) are copolymerized. Preferably, it is a combination.
Furthermore, in the polymer chain, an unsaturated carboxylic acid ester monomer unit such as a (meth)acrylic acid ester monomer unit (a2-2) is an unsaturated carboxylic acid ester unit such as a (meth)acrylic acid unit (a2-1). When placed adjacent to the system monomer units, effects such as suppressing crosslinking reactions between unsaturated carboxylic acids can be obtained.
The styrene-unsaturated carboxylic acid resin (A) in this embodiment comprises a styrene monomer unit (a1), a (meth)acrylic acid monomer unit (a2-1), and a (meth)acrylic acid ester unit. When the mer unit (a2-2) is present, the content of the (meth)acrylic acid monomer unit (a2-1) is 2 to 2 with respect to the total amount of the styrene-unsaturated carboxylic acid resin (A). The content of the (meth)acrylic acid ester monomer unit (a2-2) is preferably 0 to 20% by mass, and more preferably the content of the (meth)acrylic acid ester monomer unit (a2-2) is preferably 30% by mass. The content of the mer unit (a2-1) is 2 to 30% by mass, and the content of the (meth)acrylic acid ester monomer unit (a2-2) is 1 to 20% by mass, more preferably The content of (meth)acrylic acid monomer units (a2-1) is 2 to 25% by mass, and the content of (meth)acrylic acid ester monomer units (a2-2) is 1. The content of (meth)acrylic acid monomer units (a2-1) is 5 to 15% by mass, and more preferably 2 to 20% by mass, and (meth)acrylic acid ester monomer units. The content of (a2-2) is 2 to 13% by mass. By suppressing the content of the (meth)acrylic acid ester monomer unit (a2-2) to 20% by mass or less, a composition with low elongational viscosity and high moldability can be obtained.

<<Other monomers (a3)>>
The styrene-unsaturated carboxylic acid resin (A) in this embodiment includes the above-mentioned styrene monomer unit (a1) and (meth)acrylic acid monomer unit (a2-1) and/or (meth) It may further have a monomer unit (a3) other than the acrylic acid ester monomer unit (a2-2).
That is, in this embodiment, the other monomer unit (a3) is a styrene monomer unit (a1), a (meth)acrylic acid monomer unit (a2-1), and/or a (meth)acrylic acid monomer unit (a2-1). Copolymerization with monomers other than the two monomers shown above, without particular limitation, as long as it is copolymerizable with the ester monomer unit (a2-2), as long as it does not impair the effects of the invention. You may do so.
For example, other monomers (a3) other than the three monomers shown above include maleic anhydride, maleic acid, fumaric acid, itaconic acid, (meth)acrylonitrile, dimethyl maleate, dimethyl fumarate, diethyl fumarate. ester, ethyl fumarate, maleimide, and nuclear-substituted maleimide.
In this embodiment, when the styrene-unsaturated carboxylic acid resin (A) has other monomers (a3), the other monomers are added to the total amount of the styrene-unsaturated carboxylic 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 resin (A) in this embodiment, the styrene monomer unit (a1), (meth)acrylic acid monomer unit (a2-1), (meth)acrylic acid ester unit The content of the mer unit (a2-2) and other monomer units (a3) can be quantified using a calibration curve created using a resin in which each monomer unit is known using pyrolysis GC/MS. .
The melt flow rate at 200°C of the styrene-unsaturated carboxylic acid resin (A) in this embodiment is preferably 0.3 to 3.0, more preferably 0.4 to 2.5, and even more preferably 0. .4 to 2.0. When the melt flow rate is 0.3 or more, it is preferable from the viewpoint of fluidity, and when it is 3.0 or less, it is preferable from the viewpoint of the mechanical strength of the resin. In the present disclosure, the melt flow rate is a value measured at 200° C. and a load of 49N in accordance with ISO 1133.

The weight average molecular weight (Mw) of the styrene-unsaturated carboxylic acid resin (A) in this embodiment is preferably 100,000 to 350,000, more preferably 120,000 to 320,000. When the weight average molecular weight is from 100,000 to 350,000, a resin with an excellent balance between impact strength and fluidity can be obtained.
On the other hand, the number average molecular weight (Mn) of the styrene-unsaturated carboxylic acid resin (A) is preferably 40,000 to 150,000, more preferably 50,000 to 120,000, even more preferably 60,000 to 110,000. is within the range of The weight average molecular weight and number average molecular weight can be measured by gel permeation chromatography (GPC) in terms of polystyrene standards.

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

<Production method of styrene-unsaturated carboxylic acid resin (A)>
The method for producing the styrene-unsaturated carboxylic acid resin (A) of this embodiment will be described below.
The method for producing the styrene-unsaturated carboxylic acid resin (A) of the present embodiment involves combining a styrene monomer (a1) and an unsaturated carboxylic acid monomer (a2) (for example, a (meth)acrylic acid monomer). (a2-1) and/or (meth)acrylic acid ester monomer (a2-2)) and a solvent to prepare a mixed solution; and a step of polymerizing and reacting the mixed solution. Preferably, the method includes a polymerization step of producing a product and a step of recovering the reaction product.
The method of polymerizing the styrene-unsaturated carboxylic acid resin (A) is not particularly limited, but for example, radical polymerization, among which bulk polymerization or solution polymerization can be preferably employed.
Specifically, the polymerization method mainly includes a polymerization step in which polymerization raw materials (monomer components) are polymerized, and a devolatilization step in which volatile components such as unreacted monomers and polymerization solvent are removed from the polymerization product. and.

In this embodiment, when polymerizing the polymerization raw material to obtain the styrene-unsaturated carboxylic acid resin (A), a polymerization initiator is typically included in the polymerization raw material composition. As a polymerization initiator, organic peroxides such as 2,2-bis(t-butylperoxy)butane, 1,1-bis(t-butylperoxy)cyclohexane, n-butyl-4,4-bis(t-butylperoxy)butane, - Peroxyketals such as (butylperoxy)valerate, dialkyl peroxides such as di-t-butyl peroxide, t-butylcumyl peroxide, and dicumyl peroxide, diacyl peroxides such as acetyl peroxide and isobutyryl peroxide, and diisopropyl peroxide. Examples include peroxydicarbonates such as carbonate, peroxyesters such as t-butyl peroxyacetate, ketone peroxides such as acetylacetone peroxide, and hydroperoxides such as t-butyl hydroperoxide. From the viewpoint of decomposition rate and polymerization rate, 1,1-bis(t-butylperoxy)cyclohexane is particularly preferred.

In this embodiment, a chain transfer agent may be used as necessary during 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.

As the method for polymerizing the styrene-unsaturated carboxylic acid resin (A), solution polymerization using a polymerization solvent can be employed. As the polymerization solvent, aromatic solvents such as toluene, ethylbenzene, propylbenzene, and butylbenzene are preferred, and if necessary, polar solvents such as alcohols or ketones are combined to polymerize the styrene-unsaturated carboxylic acid resin (A). A solvent system with controlled solubility may be used.
In the present embodiment, the polymerization solvent is preferably used in an amount of 3 to 35 parts by mass, more preferably 3 to 35 parts by mass, based on 100 parts by mass of the total monomers constituting the styrene-unsaturated carboxylic acid resin (A). is in the range of 5 to 30 parts by mass. When the amount of the polymerization solvent exceeds 35 parts by mass based on 100 parts by mass of the total monomers, the polymerization rate decreases and the molecular weight of the resulting resin also decreases, so that the mechanical strength of the resin tends to decrease. Furthermore, if the polymerization solvent is less than 3 parts by mass, it may become difficult to control heat removal during polymerization. It is preferable to add the monomer in an amount of 3 to 35 parts by mass based on 100 parts by mass of the total monomers, since quality can be easily made uniform and polymerization temperature can be controlled.
In addition, when adding a monohydric alcohol having 10 or more carbon atoms, which is an optional component of the styrene resin composition of the present embodiment, from the polymerization system, the monohydric alcohol having 10 or more carbon atoms is added to 100% by mass of the total polymerization solvent. It is preferable to add monohydric alcohol in a proportion of 1 to 10% by mass.

The apparatus used in the polymerization step to obtain the styrene-unsaturated carboxylic acid resin (A) in this embodiment is not particularly limited, and may be appropriately selected according to a general method for polymerizing styrene resins. For example, in the case of bulk polymerization, a polymerization apparatus in which one or more complete mixing type reactors are connected can be used. Further, there is no particular restriction on the devolatilization step, and when carried out by bulk polymerization, the polymerization is continued until the unreacted monomer is finally reduced to preferably 50% by mass or less, more preferably 40% by mass or less, and the unreacted monomer is In order to remove volatile components such as, devolatilization treatment is performed using a known method. For example, a normal devolatilization device such as a flash drum, a twin-screw devolatilizer, a thin film evaporator, or an extruder can be used, but a devolatilization device with a small retention area is preferable. Note that the temperature of the devolatilization treatment is usually about 190 to 280°C, and more preferably 190 to 260°C from the viewpoint of suppressing decomposition. The pressure for the devolatilization treatment is usually about 0.13 to 4.0 kPa, preferably 0.13 to 3.0 kPa, and more preferably 0.13 to 2.0 kPa. Desirable devolatilization methods include, for example, a method in which volatile components are removed under reduced pressure under heating, and a method in which volatile components are removed through an extruder or the like designed for the purpose of removing volatile components.

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

With respect to the total amount (100% by mass) of the styrene resin composition, the content of the (meth)acrylic resin (B) is more than 0 to 50% by mass, more preferably 2 to 48% by mass, and 10 to 50% by mass. More preferably 46% by weight, even more preferably 14-45% by weight, most preferably 19-35% by weight. By controlling the content of the (meth)acrylic resin (B) to more than 0, especially from 2% by mass to 46% by mass, the decrease in heat resistance improved by the styrene-unsaturated carboxylic acid resin (A) is suppressed. be able to.
In this embodiment, the (meth)acrylic resin (B) is a resin containing an olefin monomer unit and an unsaturated carboxylic acid monomer unit (b1) (for example, the resin (B -4) or resin (B-7), etc.), the olefin monomer unit and the unsaturated carboxylic acid monomer unit (b1 ) The content of the resin containing is more than 0 to 20% by mass, more preferably 2 to 18% by mass, even more preferably 3 to 16% by mass, even more preferably 4 to 13% by mass, and most preferably is 5
~12% by mass. By controlling the content of the resin containing the olefin monomer unit and the unsaturated carboxylic acid monomer unit (b1) to 2% by mass or more and 20% by mass or less, the compatibility of the entire styrene resin composition can be improved. is maintained, contributing to improved moldability.
The unsaturated carboxylic acid monomer unit (b1) constituting the (meth)acrylic resin (B) of this embodiment is preferably a (meth)acrylic acid monomer unit (b1-1) and a (meth)acrylic acid monomer unit (b1-1). ) acrylic ester monomer units (b1-2), more preferably (meth)acrylic ester monomer units (b1). -2), and is more preferably a random copolymer containing a repeating unit containing two or more types of (meth)acrylic acid ester monomer units (b1-2).
In this embodiment, the (meth)acrylic acid ester monomer unit (b1-2) and the (meth)acrylic acid monomer unit (b1-1) are calculated based on the total amount of the (meth)acrylic resin (B). The upper limit of the total content is preferably 100% by mass or less, 99% by mass or less, 98% by mass or less, 80% by mass or less, 75% by mass or less, and 65% by mass or less. The lower limit of the content is preferably in the order of more than 0% by mass, 0.5% by mass or more, 1% by mass or more, 2% by mass or more, 5% by mass or more, and 10% by mass or more. The total content of the (meth)acrylic acid ester monomer unit (b1-2) and the (meth)acrylic acid monomer unit (b1-1) can be any combination of the above upper limit and the above lower limit. .
The (meth)acrylic acid ester monomer unit (b1-2) and (meth)acrylic acid monomer unit (b1-1) of this embodiment will be explained below.

<(meth)acrylic acid ester monomer (b1-2)>
The (meth)acrylic ester monomer unit (b1-2) constituting the (meth)acrylic resin (B) of this embodiment includes a methacrylic ester monomer unit and an acrylic ester monomer unit. do. In addition, as the (meth)acrylic acid ester monomer (b1-2), methyl acrylate, ethyl acrylate, (n-butyl) acrylate, (2-ethylhexyl) acrylate, (n-octyl acrylate) , benzyl acrylate, methyl methacrylate, butyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, (2-ethylhexyl) methacrylate, (n-octyl) methacrylate, methacrylate Among them, methyl acrylate, n-butyl acrylate, and methyl methacrylate are preferred because they are industrially easily available and inexpensive. The (meth)acrylic ester monomer (b1-2) can be used alone or in combination, and it is preferable to combine two types of (meth)acrylic ester monomers (b1-2).
Preferred embodiments of the unsaturated carboxylic acid monomer unit (b1) constituting the (meth)acrylic resin (B) of this embodiment include those listed above from the viewpoint of achieving both heat resistance and thermal decomposability. Among the monomer units, it is preferable to include two types of (meth)acrylic acid ester monomers (b1-2), and a combination of copolymerized methacrylic acid ester species and acrylic acid ester species is more preferable. More preferred is a methyl-methyl acrylate copolymer.
In this embodiment, the upper limit of the content of the (meth)acrylic acid ester monomer unit (b1-2) is 100% by mass or less and 99% by mass with respect to the total amount of the (meth)acrylic resin (B). The preferred amounts are 98% by mass or less, 80% by mass or less, 75% by mass or less, and 65% by mass or less. Further, the lower limit of the content is preferably in the order of 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. For the content of the (meth)acrylic acid ester monomer unit (b1-2), the above upper limit and the above lower limit can be arbitrarily combined. 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, still more preferably 3 to 98% by mass. % by weight, even more preferably from 4 to 98% by weight, even more preferably from 5 to 98% by weight, particularly preferably from 6 to 98% by weight.

<(meth)acrylic acid monomer (b1-1)>
In this embodiment, the (meth)acrylic acid monomer (b1-1) includes acrylic acid and methacrylic acid.
In this embodiment, the upper limit of the content of the (meth)acrylic acid monomer unit (b1-1) is less than 60% by mass and 58% by mass or less with respect to the total amount of the (meth)acrylic resin (B). , 45% by mass or less, 35% by mass or less, and 25% by mass or less, in this order. The lower limit of the content is preferably in the order of 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. For the content of the (meth)acrylic acid monomer unit (b1-1), the above upper limit and the above lower limit can be arbitrarily combined.

<Other monomers (b2)>
The (meth)acrylic resin (B) of this embodiment includes other than the above-mentioned (meth)acrylic acid monomer unit (b1-1) and (meth)acrylic acid ester monomer unit (b1-2). It may further have a monomer unit (b2). In other words, if the other monomer (b2) is copolymerizable with the (meth)acrylic acid monomer (b1-1) and/or the (meth)acrylic acid ester monomer (b1-2), it is considered an invention. It may be copolymerized with monomers other than the monomers shown above, without any particular restriction, as long as the effects of the above are not impaired. For example, other monomers (b2) other than the monomers shown above include olefins (olefinic monomers) such as styrene, ethylene or propylene, maleic anhydride, maleic acid, fumaric acid, itaconic acid, Examples include dimethyl maleate, dimethyl fumarate, diethyl fumarate, ethyl fumarate, maleimide, and nuclear-substituted maleimide.
Moreover, as a preferable aspect of the other monomer unit (b2) of this embodiment, it may be an olefin monomer unit (for example, an ethylene monomer unit, a propylene monomer unit).
In this embodiment, the content of other monomer units (b2) is preferably 0 to 90% by mass, and 0 to 85% by mass, based on the total amount of (meth)acrylic resin (B). It is more preferably from 0 to 80% by mass, even more preferably from 0 to 70% by mass, even more preferably from 0 to 60% by mass, and even more preferably from 0 to 50% by mass. Even more preferably.

<Preferred form of (meth)acrylic resin (B)>
The preferred (meth)acrylic resin (B) of this embodiment is preferably a binary or tertiary copolymer.

In the (meth)acrylic resin (B) of the present embodiment, the content of the (meth)acrylic acid ester monomer unit (b1-2) in the (meth)acrylic resin (B) is (meth) It is preferably 2.0 to 100% by mass, more preferably 5.0 to 99.5% by mass, even more preferably 8.0 to 98.5% by mass, based on the total amount of acrylic resin (B). Even more preferably, it is 10 to 98.0% by mass. By setting the content of the (meth)acrylic acid ester monomer (b1-2) in the range of 10.0 to 100% by mass, it can withstand kneading and extrusion with other resins and molding processing at temperatures below 300°C. become. Therefore, it is possible to suppress a significant decrease in heat resistance when the styrene-unsaturated carboxylic acid resin (A) and (meth)acrylic resin (B) are mixed. As for the type of (meth)acrylic acid ester monomer (b1-2), methyl acrylate or methyl methacrylate is preferred because of its heat resistance, industrial availability, and low cost. In addition, as a preferable aspect of the (meth)acrylic resin (B) of this embodiment, a methyl methacrylate monomer unit and one or more types of monomer units other than the methyl methacrylate monomer unit are used. It is preferable that it is a copolymer containing. Monomer units other than methyl methacrylate monomer unit literally include other monomer units (b2) and (meth)acrylic acid monomer units (b1-1), but also methacrylic acid It also includes (meth)acrylic acid ester monomers (b1-2) other than methyl monomer units.

When the (meth)acrylic resin (B) of this embodiment does not contain an olefinic monomer unit such as an ethylene monomer unit as a monomer unit, the weight average of the (meth)acrylic resin (B) The molecular weight (Mw) is preferably from 50,000 to 5,000,000, more preferably from 60,000 to 1,000,000, still more preferably from 70,000 to 300,000, even more preferably from 80,000 to 200,000. By setting the weight average molecular weight (Mw) of the (meth)acrylic resin (B) to 50,000 or more, strength and melt tension can be imparted when kneaded with the styrene-unsaturated carboxylic acid resin (A). By setting the weight average molecular weight (Mw) to 5 million or less, the viscosity difference with the styrene-unsaturated carboxylic acid resin (A) is suppressed, and the (meth)acrylic resin (B) is contained in the styrene resin composition. The composition can be dispersed well, suppresses the generation of unmelted substances derived from the (meth)acrylic resin (B), and can be used to produce molded products such as foamed extruded sheets with good appearance. Obtainable.
In addition, in the present invention, the number average molecular weight (Mn), weight average molecular weight (Mw), and Z average molecular weight (Mz) of the (meth)acrylic resin (B), and 10,000 or less in the styrene resin composition. The proportion of high molecular weight components is a value measured using gel permeation chromatography (GPC) as described in the Examples section below.

The (meth)acrylic resin (B) of this embodiment is preferably a resin having four or more inflection points in its differential molecular weight distribution curve. The molecular weight distribution of general resins is monodisperse, and the number of inflection points of the differential molecular weight distribution curve is two. In this specification, a resin whose differential molecular weight distribution curve has four or more inflection points means a resin whose differential molecular weight distribution curve has two or more maximum points, for example, a bimodal molecular weight distribution. This may apply to resins and the like.
In this specification, "differential molecular weight distribution curve" refers to the vertical axis as "dw/dLog(M)" (concentration fraction as molecular weight) when determining the molecular weight distribution curve of (meth)acrylic resin (B) by SEC method. (value differentiated by the logarithm of), where w represents the concentration fraction and M represents the molecular weight.
Further, the Mw/Mn value of the (meth)acrylic resin (B) is preferably 1.5 or more, more preferably 1.7 or more, even more preferably 3.0 or more. By incorporating a (meth)acrylic resin (B) having four or more inflection points of the differential molecular weight distribution curve and a wide molecular weight distribution into the styrenic resin composition, the styrenic resin composition can be improved by a low molecular weight component. While keeping the viscosity low, the melt tension can be improved due to the effect of the polymer component.

Note that when the styrene resin composition of the present embodiment is divided into a first molecular weight component having a molecular weight of 10,000 or less and a second molecular weight component having a molecular weight of more than 10,000, the first molecular weight component having a molecular weight of 10,000 or less is a predetermined amount. It was confirmed that when it is contained in a styrenic resin composition, the elongational viscosity of the molten resin tends to be lower, and the moldability tends to be further improved. The proportion of the first molecular weight component having a molecular weight of 10,000 or less in the present embodiment is preferably within the range of 0.3 to 3.0% by mass based on the total amount of the styrenic resin composition. The range is more preferably from 0.7 to 2.6% by weight, even more preferably from 0.9 to 2.5% by weight, and most preferably from 1.0 to 2.1% by weight. When the amount of the first molecular weight component is less than 0.5% by mass, the elongational viscosity of the molten resin increases and moldability decreases. On the other hand, when the amount of the first molecular weight component is more than 3.0% by mass, the mechanical strength of the molded article decreases due to the excessive presence of the low molecular weight component. By controlling the amount of the first molecular weight component to 0.5 to 3.0% by mass, it is possible to obtain a styrenic resin composition that provides a foamed extruded sheet with excellent both mechanical strength and moldability. The amount of the first molecular weight component with a molecular weight of 10,000 or less is determined from the molecular weight distribution obtained by measuring the molecular weight in terms of standard polystyrene using gel permeation chromatography (GPC) using a calibration curve method using standard polystyrene. , the proportion of components having a molecular weight of 10,000 or less in the entire composition.
In a preferred form of this embodiment, a (meth)acrylic resin (B) having four or more inflection points of a differential molecular weight distribution curve and a wide molecular weight distribution is contained in the styrenic resin composition. The proportion of the molecular weight component increases, and the first molecular weight component having a molecular weight of 10,000 or less in the matrix polymer portion of the styrenic resin composition increases.

<Method for producing (meth)acrylic resin (B)>
The method for producing the (meth)acrylic resin (B) of the present embodiment is not particularly limited, but may include unsaturated carboxylic acid monomer units (b1) and other monomers as necessary. It can be produced by processes such as bulk polymerization, solution polymerization in which a solvent is added, or suspension polymerization in which an organic layer is dispersed in water using a suspending agent.

"Ratio of melt tension to extensional viscosity"
In this embodiment, by setting the ratio of melt tension to extensional viscosity (MT/EV) of the styrenic resin composition to the range described below, a styrenic resin composition with excellent moldability and molding thereof are described. Foamed extruded sheets and molded products were obtained. In order to obtain a resin with excellent moldability, it is necessary to achieve both ease of stretching of the molten resin and resistance to cutting of the molten resin.

The melt tension (MT) of the styrene resin composition in this embodiment is a physical property value adopted as an index of the difficulty of cutting the molten resin, and specifically, it is measured at a temperature of 220°C and a drawing speed of 3.1 m/min. value (gf). The MT of the styrenic resin composition in this embodiment is preferably 5.0 gf or more, more preferably 6.0 gf or more, even more preferably 7.0 gf or more, even more preferably 8.0 gf or more, even more preferably is 8.5 gf or more, most preferably 10.0 gf or more. The upper limit of the MT is preferably 130 gf or less, more preferably 80 gf or less, even more preferably 40 gf or less, even more preferably 30 gf or less, and most preferably 20 gf or less. By controlling the MT of the styrenic resin composition of the present embodiment within the range of 5 to 130 gf, a styrenic resin composition in which the resin is difficult to break during melting can be obtained.
The elongational viscosity (EV) of the styrene resin composition in this embodiment is a physical property value adopted as an index of the elongation of the molten resin. This is the measured value (MPa·s) at .5. The EV of the styrenic resin composition in this embodiment is 0.6 MPa·s or less, preferably 0.59 MPa·s or less, more preferably 0.58 MPa·s or less, still more preferably 0.57 MPa·s Below, it is still more preferably 0.56 MPa·s or less, even more preferably 0.55 MPa·s or less, and most preferably 0.53 MPa·s or less. The lower limit is preferably 0.15 MPa·s or more, more preferably 0.10 MPa·s or more, even more preferably 0.15 MPa·s or more, and most preferably 0.20 MPa·s or more. By particularly controlling the EV of the styrenic resin composition of the present embodiment in the range of 0.15 to 0.6 MPa·s, it is possible to obtain a styrenic resin composition in which the resin is more easily extensible when melted.
Effective means for reducing the EV of the styrene resin composition to 0.6 MPa·s or less include the following (a) to (d).
(a) The content of the (meth)acrylic resin (B) is greater than 0 to 46% by mass with respect to the total amount of the styrene resin composition.
(b) The first molecular weight component having a molecular weight of 10,000 or less in the matrix polymer portion of the styrene resin composition is 0.5 to 3.0% by mass.
(c) 10% by mass or more of a (meth)acrylic resin (B) having four or more inflection points in the differential molecular weight distribution curve is contained based on the total amount of the styrene resin composition.
(d) The styrenic resin composition contains one or more high melt tension and low viscosity reducing components.
By taking one or more of the above measures (1) to (4), it becomes easier to control the EV of the styrenic resin composition to 0.6 MPa·s or less.

In the present embodiment, the value of the ratio of melt tension to extensional viscosity (MT/EV) of the styrenic resin composition is preferably 16.0 or more, more preferably 16.6 or more, and even more preferably 16.8. Above, it is even more preferably 18.0 or more, even more preferably 19.5 or more. The upper limit of the melt tension ratio is preferably 400 or less, more preferably 300 or less, still more preferably 200 or less, even more preferably 100 or less, and most preferably 70 or less.
When MT/EV is 16 or more, the molten resin is less likely to be cut, and the problem that the resin is cut during molding is less likely to occur. In particular, when the EV is more than 0.6 MPa·s and the MT/EV is less than 16, the molten resin tends to be easily cut, which is not preferable because the problem of the resin being cut during molding occurs. On the other hand, if the EV is more than 0.6 MPa·s and the value of MT/EV is more than 400, the load required to stretch the resin during molding becomes excessively large, leading to deterioration of moldability. In this embodiment, in order to obtain a resin with excellent moldability, it is necessary to balance the ease of stretching of the molten resin and the difficulty of cutting the molten resin, and by setting the MT/EV in the range of 16 to 400, It is possible to obtain a styrenic resin composition with excellent moldability in which the molten resin is moderately stretchable and difficult to break, and a foam extrusion sheet and a molded article formed by molding the same.

In the present embodiment, the following (1) to (10) are effective means for setting the ratio of melt tension to extensional viscosity (MT/EV) of the styrenic resin composition within a preferable range. It will be done.

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

"Other ingredients"
The styrenic resin composition in this embodiment may include the following optional components, such as a high melt tension and low viscosity component, inorganic particles (H), a monohydric alcohol having 10 or more carbon atoms, and optional additive components. It can contain one or more selected from the group consisting of:

<High melt tension low viscosity component>
The styrenic resin composition in the embodiment may contain one or more high melt tension and viscosity reducing components, if necessary. The high melt tension and low viscosity component is an additive that has the effect of improving the MT of the styrenic resin composition by 5% or more and/or reducing the EV of the styrenic resin composition by 5% or more. It is. Specifically, (meth)acrylonitrile-diene-styrene resin (C), impact-resistant styrene resin (D), styrenic elastomer (E), acrylic elastomer (F), and core-shell type rubbery polymer. Examples include particles (G). This increases the value of the ratio of melt tension to elongational viscosity (MT/EV) of the styrenic resin composition, and improves the moldability of solid sheets and foam sheets. In other words, from the viewpoint of improving moldability, the styrenic resin composition in the embodiment includes (meth)acrylonitrile-diene-styrene resin (C), impact-resistant styrenic resin (D), and styrenic elastomer (E). , acrylic elastomer (F), and core-shell type rubbery polymer particles (G).

<(meth)acrylonitrile-diene-styrene resin (C)>
As a preferred aspect of this embodiment, the styrenic resin composition of this embodiment includes a (meth)acrylonitrile monomer unit (c3), a conjugated diene monomer unit (c2), and a styrene monomer unit ( c1) (meth)acrylonitrile-diene-styrene resin (C) (also simply referred to as resin (C)).
When the styrene resin composition contains an appropriate amount of (meth)acrylonitrile-diene-styrene resin (C), a styrene resin composition that can be molded into a molded article with excellent strength can be obtained.
The (meth)acrylonitrile-diene-styrene resin (C) of this embodiment comprises a (meth)acrylonitrile monomer unit (c3), a styrene monomer (c1), and other monomer components as necessary. A rubber-like polymer whose main component is a conjugated diene monomer unit (c2) in a polymer matrix (C1) containing a copolymer formed by polymerizing and other resins blended as necessary. It refers to a resin obtained by dispersing particles (=rubber-like polymer particles (C2)), and can be, for example, a so-called ABS resin.
In other words, the (meth)acrylonitrile-diene-styrene resin (C) of this embodiment contains a polymer matrix (C1) and rubbery polymer particles (C2). The polymer matrix (C1) is formed by polymerizing a (meth)acrylonitrile monomer unit (c3), a styrene monomer (c1), and other monomer components blended as necessary. Contains a copolymer and other resins blended as necessary. Further, the rubbery polymer particles (C2) are particles of a rubbery polymer whose main component is a conjugated diene monomer unit (c2).
In addition, in this specification, "consisting as a main component" means that it occupies 50% by mass or more based on the whole. Therefore, for example, particles of a rubbery polymer mainly composed of a conjugated diene monomer unit (c2) (for example, a butadiene monomer unit (c2)) means that the entire rubbery polymer particle (C2) is On the other hand, it means that the conjugated diene monomer unit (c2) occupies 50% by mass or more.

Examples of the styrenic monomer (c1) include styrene, α-methylstyrene, o-methylstyrene, p-methylstyrene, ethylstyrene, pt-butylstyrene, and vinylnaphthalene. Among these, styrene is preferred from the viewpoint of versatility. The styrenic monomer (c1) may be used alone or in combination of two or more.

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

Examples of the (meth)acrylonitrile monomer unit (c3) include an acrylonitrile unit and a methacrylonitrile unit. Among these, acrylonitrile units are preferred from an industrial standpoint. The (meth)acrylonitrile monomer unit (c3) may be used alone or in combination of two or more.

<<Preferred form of (meth)acrylonitrile-diene-styrene resin (C)>>
The mass ratio of the (meth)acrylonitrile monomer unit (c3) to the styrene monomer unit (c1) in the polymer matrix (C1) constituting the (meth)acrylonitrile-diene-styrene resin (C) is , (meth)acrylonitrile monomer unit (c3)/styrene monomer unit (c1) = 5/95 to 40/60, more preferably 10/90 to 35/65, more preferably 15/ It ranges from 85 to 30/70, most preferably from 20/80 to 25/75. In particular, by setting the mass ratio in the range of 20/80 to 30/70, it has excellent compatibility with the (meth)acrylic resin (B) and has an effect of improving mechanical strength when added to a styrene resin composition. It gets expensive.

(meth)acrylonitrile-diene-styrene resin (C) The content of rubber-like polymer particles (C2) mainly composed of conjugated diene monomer units (c2) is as follows: (meth)acrylonitrile-diene-styrene resin (C) The amount is preferably 5 to 40% by weight, more preferably 10 to 35% by weight, and even more preferably 15 to 30% by weight, based on the total amount of diene-styrene resin (C). By setting the content of the rubbery polymer particles (C2) in the range of 5 to 40% by mass, an excellent balance between rigidity and impact resistance can be achieved when added to a styrenic resin composition.

The average particle diameter of the rubbery polymer particles (C2) of the (meth)acrylonitrile-diene-styrene resin (C) is preferably 0.10 to 1.00 μm, more preferably 0.13 to 0.90 μm, The range is more preferably from 0.16 to 0.70 μm, even more preferably from 0.20 to 0.50 μm. In particular, by setting the average particle diameter in the range of 0.20 to 0.50 μm, the effect of improving the impact strength of the styrenic resin composition is excellent.
In the present disclosure, the average particle diameter is measured from a cross-sectional observation image using a transmission electron microscope, as shown in the Examples section below.
In addition, a preferable form of the rubbery polymer particles (C2) is a solid rubbery particle having a core composed of a conjugated diene monomer unit (c2), and a styrene-based monomer so as to cover the core. It may have a structure coated with a polymer containing a mer unit (c1) and a (meth)acrylonitrile monomer unit (c3).

The polymer matrix (C1) of the (meth)acrylonitrile-diene-styrene resin (C) contains a copolymer containing (meth)acrylonitrile monomer units (c3) and styrene monomer (c1) as main components. In addition to the combination, other polymers may be included in an amount of 25% by mass or less based on the total amount of the (meth)acrylonitrile-diene-styrene resin (C). For example, the heat resistance of the (meth)acrylonitrile-diene-styrene resin (C) may be improved by adding a styrene-acrylonitrile-N-phenylmaleimide copolymer or the like.

In the present embodiment, the melt flow rate of the (meth)acrylonitrile-diene-styrene resin (C) at 200°C is preferably 0.2 to 7.0 g/10 minutes, more preferably 0.3 to 6. 0 g/10 minutes, more preferably 0.4 to 5.0 g/10 minutes. If the above melt flow rate is in the range of 0.2 to 7.0 g/10 minutes, the miscibility with the styrene-unsaturated carboxylic acid resin (A) and (meth)acrylic resin (B) is good, and Mechanical strength is also good. In the present disclosure, the melt flow rate is a value measured at 200° C. and a load of 49N in accordance with ISO 1133.

<<Method for producing (meth)acrylonitrile-diene-styrene resin (C)>>
The method for producing the (meth)acrylonitrile-diene-styrene resin (C) involves graft polymerization of a resin that is the main component of the polymer matrix (C1) prepared in advance by radical bulk polymerization or solution polymerization, and rubber latex. Prepared ABS rubbery polymer particles (
There is a method of preparing rubber-like polymer particles (C2) and a polymer matrix (C1) at the same time, such as a method of preparing C2) by polymerization compounding and a method of preparing the impact-resistant styrenic resin (D) described later. , you can choose the most suitable method according to your needs.
The difference between the (meth)acrylonitrile-diene-styrene resin (C) and the impact-resistant styrene resin (D) described below is the content of (meth)acrylonitrile monomer units. That is, the content of (meth)acrylonitrile monomer units in the former (meth)acrylonitrile-diene-styrene resin (C) is based on the total amount of (meth)acrylonitrile-diene-styrene resin (C). , contains more than 3% by mass. On the other hand, the content of (meth)acrylonitrile monomer units in the impact-resistant styrenic resin (D) described below is 3% by mass or less based on the total amount of the impact-resistant styrenic resin (D).

<Impact-resistant styrenic resin (D)>
As a preferred aspect of this embodiment, the styrenic resin composition preferably contains an impact-resistant styrenic resin (D) (also simply referred to as resin (D)). When the styrene resin composition contains an appropriate amount of the rubber-modified styrenic resin (D), a styrenic resin composition capable of producing a molded article with excellent strength can be obtained.
The rubber-modified styrenic resin (D) of this embodiment is contained in a polymer matrix (D1) of a resin consisting of a styrene monomer unit (d1) and other monomer units (d3) contained as necessary. , dispersing particles of a rubbery polymer (D2) (=rubberlike polymer particles (D2)) and polymerizing the styrenic monomer (d1) in the presence of the rubbery polymer (D2). It may be a so-called high impact polystyrene resin (HIPS resin) obtained by. In other words, the impact-resistant styrenic resin (D) of this embodiment contains a polymer matrix (D1) and rubbery polymer particles (D2). The polymer matrix (D1) contains a polymer obtained by polymerizing a styrene monomer (d1) and other monomers (d3) blended as necessary. Further, the rubbery polymer particles (D2) are particles of a rubbery polymer (D2) containing a conjugated diene monomer unit (d2) as a main component, and if necessary, a styrene monomer unit (d1). ) may be grafted onto the surface of the particles.

The content of the impact-resistant styrenic resin (D) in the styrenic composition of the present embodiment is preferably 0.5 to 30% by mass, more preferably 2% by mass, based on the total amount of the styrenic resin composition. ~20% by weight, more preferably 3~15% by weight. By setting the content of the impact-resistant styrenic resin (D) in the range of 3 to 15% by mass, a styrenic resin composition with even better strength can be obtained.

<<Rubber-like polymer particles (D2)>>
In this embodiment, the rubbery polymer (D2) constituting the rubbery polymer particles (D2) in the impact-resistant styrene resin (D) is formed from a conjugated diene monomer (d2). is preferable, and a polymer having a conjugated diene monomer unit (d2) is more preferable. Specific examples of the rubbery polymer (D2) that can be used include polybutadiene, polyisoprene, natural rubber, polychloroprene, styrene-butadiene copolymer, acrylonitrile-butadiene copolymer, etc. From an industrial standpoint, polybutadiene and styrene-butadiene copolymers are preferred. As the polybutadiene, high-cis polybutadiene with a high cis content, low-cis polybutadiene with a low cis content, or both of these can be used. The structure of the styrene-butadiene copolymer may be a random structure, a block structure, or a combination thereof. These rubbery polymers may be used alone or in combination of two or more. Saturated rubber obtained by hydrogenating butadiene rubber can also be used.
In the present specification, "conjugated diene monomer" is a general term for the aforementioned conjugated diene monomer (c2), conjugated diene monomer (d2), and conjugated diene monomer (e2). Moreover, in this specification, "rubber-like polymer particles" is a general term for rubber-like polymer particles (C2) and rubber-like polymer particles (D2).
The conjugated diene monomer is a diolefin having a pair of conjugated double bonds among the monomer units constituting the rubbery polymer particles, such as 1,3-butadiene, 2-methyl -1,3-butadiene (isoprene), 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 1,3-hexadiene and the like.
The rubbery polymer particles (D2) in this embodiment are a polymer containing a styrene monomer unit (d1) in the dispersed particles of the rubbery polymer (D2), or a polymer containing the styrenic monomer unit (d1) in the dispersed particles of the rubbery polymer (D2). It is preferable to include a polymer containing d1) and other monomers (d3). The form of the encapsulation is preferably a so-called salami structure type dispersed particle in which a plurality of rubbery polymers (D2) encapsulate a domain phase of a polymer having styrene monomer units (d1).
<<Other monomers (d3)>>
Other monomers (units) (d3) that are optional components of the impact-resistant styrenic resin (D) of this embodiment include methyl acrylate, ethyl acrylate, propyl acrylate, and acrylic acid (n-butyl). , (meth)acrylic acid ester monomers such as isopropyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, (n-butyl) methacrylate, and isopropyl methacrylate, which are easy to obtain industrially. Among them, acrylic acid (n-butyl) and methyl methacrylate are preferred.
In this embodiment, the content of other monomers (units) (d3) in the impact-resistant styrenic resin (D) is 70% by mass or less with respect to the total amount of the impact-resistant styrenic resin (D). The content is preferably 60% by mass or less, and more preferably 60% by mass or less.

<<Content of conjugated diene monomer unit (d2)>>
In this embodiment, the content of the conjugated diene monomer unit (d2) in the impact-resistant styrenic resin (D) is preferably 0.000000000000000000000 with respect to the total amount of the impact-resistant styrenic resin (D). The content is 5 to 15.0% by weight, more preferably 1.0 to 13.0% by weight, even more preferably 2.0 to 12.0% by weight. The content of the conjugated diene monomer unit (d2) in the impact-resistant styrenic resin (D) and the styrenic resin composition can be determined by the procedure described in the Examples section below, or by an equivalent method. can be measured.

<<Average particle diameter of rubbery polymer particles (D2)>>
The rubbery polymer (D2), which is the rubber component in the impact-resistant styrenic resin (D) in this embodiment, is present in the styrenic resin composition as particles of the rubbery polymer (D2). In this case, the average particle diameter of the rubbery polymer particles (D2) is preferably 0.3 to 5.0 μm, more preferably 0.5 to 4.0 μm, and still more preferably 0.7 to 3.0 μm. The impact-resistant styrenic resin (D) is obtained by polymerizing the styrenic monomer (d1) in a reactor equipped with a stirrer in the presence of rubbery polymer particles (D2). The average particle diameter of the particles (D2) can be adjusted by adjusting the rotation speed of the stirrer, the molecular weight of the rubbery polymer (D2) used, etc. In the present disclosure, the average particle diameter of the rubbery polymer particles (D2) is a value measured from a cross-sectional observation image using a transmission electron microscope, as shown in the Examples section below. The rubbery polymer particles (D2) are elongated during foaming in the foamed sheet described below, and the particle size increases by about 150 to 400%.

In this embodiment, the melt flow rate at 200°C of the impact-resistant styrenic resin (D) is preferably 0.5 to 10.0 g/10 minutes, more preferably 0.7 to 8.0 g/10 minutes. , more preferably 1.0 to 7.0 g/10 minutes. If the above melt flow rate is in the range of 0.5 to 10.0 g/10 minutes, the miscibility with the styrene-unsaturated carboxylic acid resin (A) and (meth)acrylic resin (B) is good, and Mechanical strength is also good. In the present disclosure, the melt flow rate is a value measured at 200° C. and a load of 49N in accordance with ISO 1133.

<<Production method of impact-resistant styrenic resin (D)>>
The method for producing the impact-resistant styrenic resin (D) is not particularly limited, but in the presence of the rubbery polymer (D2), the styrenic monomer (d1) and other monomers as necessary (d3), and bulk polymerization (or solution polymerization) in which a solvent is polymerized, bulk-suspension polymerization in which the reaction transitions to suspension polymerization, or styrene-based It can be produced by emulsion graft polymerization in which monomer (d1) is polymerized. In bulk polymerization, a rubbery polymer (D2), a styrene monomer (d1), and if necessary, other monomers (d3), an organic solvent, an organic peroxide, and/or a chain transfer agent are added. It can be produced by continuously supplying the added mixed solution to a polymerization apparatus configured by connecting a complete mixing reactor or a tank reactor and a plurality of tank reactors in series.

<Styrenic elastomer (E)>
As a preferred aspect of this embodiment, the styrenic resin composition preferably further contains a styrene elastomer (E) (also simply referred to as elastomer (E)). The styrenic elastomer (E) used in the styrenic resin composition of the present invention has hard blocks made of styrene monomers (units) (e1) and soft blocks made of conjugated diene monomers (units) (e2). It is a block copolymer. As the elastomer (E), a block copolymer having a hard block of styrene monomer (unit) (e1) and a soft block of butadiene monomer unit is more preferable.
Examples of the styrene monomer (e1) include the same monomers as the styrene monomer (a1). Furthermore, examples of the conjugated diene monomer (e2) include the same monomers as the conjugated diene monomer (c2).

The chain structure of block copolymerization of styrene elastomer (E) is styrene monomer (e1)-butadiene diblock type, styrene monomer (e1)-butadiene-styrene monomer (e1) triblock type, block type, butadiene-styrene monomer (e1)-butadiene monomer (e1), etc.; Block-type ones are preferred.

The content of the styrene monomer units (e1) and conjugated diene monomer units (e2) constituting the styrenic elastomer (E) is such that the content of the styrene monomer units (e1) is 30 to 30%. The content of styrenic monomer units (e1) is preferably 70% by mass, more preferably 35 to 65% by mass, and the content of conjugated diene monomer units (e2) is 100% by mass. is the remainder of If the content of the styrene monomer unit (e1) is 35 to 65%, the dispersibility in the styrene-unsaturated carboxylic acid resin (A) will be moderately good, resulting in excellent mechanical strength and appearance. You can get something.
Methods for producing styrene-based elastomers (E) such as styrene-butadiene elastomers include radical polymerization, anionic polymerization, and polymer reaction methods, with anionic polymerization being preferred from an industrial standpoint.

When the content of the conjugated diene monomer (e2) in the styrenic elastomer (E) exceeds 50% by mass, the content of the styrenic elastomer (E) in the styrenic composition of this embodiment is The amount may be preferably 0.5 to 15% by weight, more preferably 1 to 12% by weight, and even more preferably 2 to 7% by weight based on the total amount of the styrenic resin composition. On the other hand, when the content of the conjugated diene monomer unit (e2) in the styrenic elastomer (E) is 50% by mass or less, the content of the styrenic elastomer (E) in the styrene composition is The amount is preferably 3 to 30% by weight, more preferably 5 to 20% by weight, and more preferably 7 to 15% by weight based on the total amount of the resin composition. By setting it as the said range, when it adds to a styrenic resin composition, a fall in heat resistance can be suppressed and mechanical strength can be improved.
Note that the difference between the styrene elastomer (E) and the acrylic elastomer (F) described below is the content of styrene monomer units. That is, the content of styrene monomer units in the former styrene elastomer (E) is more than 3% by mass based on the total amount of the styrene elastomer (E). On the other hand, the content of styrene monomer units in the acrylic elastomer (F) described below is 3% by mass or less based on the total amount of the acrylic elastomer (F).

<Acrylic elastomer (F)>
As a preferred aspect of this embodiment, the styrenic resin composition preferably contains an acrylic elastomer (F) (also simply referred to as elastomer (F)). The acrylic elastomer (F) used in the resin composition of the present invention is a block copolymer in which the hard block is a methyl methacrylate monomer unit (f1) and the soft block is an acrylic ester monomer unit (f2). That's true. As the acrylic elastomer (F), a block copolymer having a hard block of methyl methacrylate monomer (unit) and a soft block of acrylic ester monomer unit (f2) is more preferable.
Therefore, the acrylic elastomer (F) is a block copolymer, but the (meth)acrylic resin (B) is a random polymer or an alternating polymer, which is the difference between the two.
Examples of the acrylic ester monomer (f2) include the same monomers as the acrylic ester monomer units among the (meth)acrylic ester monomer units (b1).

The chain structure of block copolymerization of acrylic elastomer (F) is methyl methacrylate-acrylic ester (f2) block type, methyl methacrylate-acrylic ester (f2)-methyl methacrylate triblock type, acrylic ester ( Examples include f2)-methyl methacrylate-acrylic ester (f2) triblock type, and from the viewpoint of improving mechanical strength, triblock type of methyl methacrylate-acrylic ester (f2)-methyl methacrylate is preferred.

The content of methyl methacrylate monomer (f1) and acrylic acid ester monomer (f2) constituting the acrylic elastomer (F) is such that the content of methyl methacrylate monomer (f1) is 20 to 20. It is preferably 65% by weight, more preferably 30-55% by weight. On the other hand, the content of the acrylic acid ester monomer (f2) was 100% by mass. If the content of methyl methacrylate monomer (f1) is 20 to 65%, the dispersibility in the styrene-unsaturated carboxylic acid resin (A) will be moderately good, and the resin will have excellent mechanical strength and appearance. You can get something.

The content of the acrylic elastomer (F) in the styrenic composition of the present embodiment is preferably 0.5 to 20% by mass, more preferably 1 to 17% by mass, based on the total amount of the styrene resin composition. %, more preferably 2 to 15% by mass, and by setting it in the range of 0.5 to 20% by mass, when added to a styrenic resin composition, decrease in heat resistance is suppressed and mechanical strength is improved. be able to.

<Core-shell type rubbery polymer particles (G)>
As a preferred aspect of this embodiment, the styrenic resin composition of this embodiment is a rubber containing a conjugated diene monomer unit (g1-1) or a (meth)acrylate monomer unit (g1-2). A core shell formed by grafting a copolymer containing a styrene monomer unit (g2-1) and/or a (meth)acrylic acid ester monomer unit (g2-2) to a shaped particle (corresponding to the core part) It is preferable to further contain rubber-like polymer particles (G) (also simply referred to as core-shell particles (G)).
The core-shell type rubbery polymer particles (G) of this embodiment are rubbery particles containing a conjugated diene monomer unit (g1-1) or a (meth)acrylate monomer unit (g1-2). is a core part, and a shell part that at least partially covers the core part contains a styrene monomer unit (g2-1) and/or a (meth)acrylic acid ester monomer unit (g2-2). Contains a graft copolymer. In other words, at least a portion of the core portion is coated with a graft copolymer containing a styrene monomer unit (g2-1) and/or a (meth)acrylic acid ester monomer unit (g2-2). It has a unique structure. The number of the core portions is preferably one.

The content of the core-shell type rubbery polymer particles (G) is preferably 1 to 45% by mass, more preferably 2 to 40% by mass, even more preferably 3 to 35% by weight, even more preferably 4 to 30% by weight, most preferably 5 to 25% by weight. When the content is 1% by mass or more, mechanical strength and low-temperature impact resistance can be improved, and when the content is 25% by mass or less, a decrease in heat resistance and rigidity can be prevented.
The conjugated diene monomer (g1-1) constituting the rubbery particles of the core-shell type rubbery polymer particles (G) is a diolefin having a pair of conjugated double bonds, for example, 1,3- Examples include butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, and 1,3-hexadiene.
The (meth)acrylic acid ester monomer units (g1-2) constituting the rubbery particles of the core-shell type rubbery polymer particles (G) include methyl acrylate, ethyl acrylate, and n-butyl acrylate. ), acrylic acid (2-methoxyethyl), acrylic acid (2-ethylhexyl), acrylic acid (n-octyl), benzyl acrylate, etc. From an industrial perspective, ethyl acrylate, acrylic acid (n-butyl) ) is preferred.
The styrene monomer unit (g2-1) constituting the graft copolymer (shell portion) of the core-shell type rubbery polymer particles (G) is not particularly limited, but includes, for example, styrene, α-methylstyrene, etc. , β-methylstyrene, paramethylstyrene, orthomethylstyrene, metamethylstyrene, chlorostyrene, bromostyrene, and the like. Particularly from an industrial standpoint, styrene and α-methylstyrene are preferred, and styrene is more preferred.
The (meth)acrylic acid ester monomer unit (g2-2) constituting the graft copolymer (shell portion) of the core-shell type rubbery polymer particles (G) is composed of a methacrylic acid ester monomer unit and acrylic acid. Contains ester monomer units. In addition, (meth)acrylic acid ester monomer units include methyl acrylate, ethyl acrylate, (n-butyl) acrylate, (2-ethylhexyl) acrylate, (n-octyl) acrylate, and benzyl acrylate. , methyl methacrylate, butyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, (2-ethylhexyl) methacrylate, (n-octyl) methacrylate, benzyl methacrylate, etc. Methyl acrylate, n-butyl acrylate, and methyl methacrylate are preferred because they are easily available industrially and are inexpensive.

The content of the conjugated diene monomer (g1-1) or (meth)acrylic acid ester monomer unit (g1-2) constituting the rubbery particles in the core-shell type rubbery polymer particles (G) is: Preferably 30 to 90% by mass, more preferably 40 to 85% by mass, even more preferably 50 to 80% by mass, even more preferably 55 to 75% by mass, based on the total amount of rubbery polymer particles (G). be. It is preferable that the higher the content of the monomer units constituting the rubbery particles, the greater the improvement in mechanical strength can be achieved with a smaller amount added. On the other hand, if the content of the monomer units constituting the rubber particles is too high, the content of the graft copolymer containing (meth)acrylic acid ester monomer units (g2-2) will decrease, and the styrene - The decrease in compatibility with the unsaturated carboxylic acid resin (A) causes a decrease in the effect of improving mechanical strength.

The content of the styrene monomer unit (g2-1) in the graft copolymer of the core-shell type rubbery polymer particles (G) is 0 to 90% by mass, more preferably 0 to 70% by mass, even more preferably is 0 to 10% by mass. By controlling the content of the styrene monomer unit (g2) in the graft copolymer to 10% by mass or less, the methyl (meth)acrylate monomer unit (g2-2) contained in the graft chain can be reduced. The content increases, and compatibility with the matrix polymer portion constituting the styrenic resin composition of this embodiment can be ensured, and the effect of improving mechanical strength can be efficiently obtained.
The matrix polymer portion essentially contains resin (A) and resin (B), and optionally contains polymer matrix (C-1), polymer matrix (D-1), and styrene elastomer (E ), an acrylic elastomer (F), a monohydric alcohol having 10 or more carbon atoms, and optional additive components. In other words, the matrix polymer portion refers to components other than the various rubbery polymer particles and inorganic particles (H) contained in the styrenic resin composition.

The content of (meth)acrylic acid ester monomer units (g2-2) in the graft copolymer of core-shell type rubbery polymer particles (G) is 10 to 100% by mass, more preferably 30 to 96% by mass. %, more preferably 70 to 95% by mass. By setting the content of the methyl (meth)acrylate monomer unit (g2-2) in the graft copolymer to 70% by mass or more, the content of the methyl (meth)acrylate monomer unit (g2-2) can be set to 70% by mass or more, so that the content of the methyl (meth)acrylate monomer unit (g2-2) is 70% by mass or more. Compatibility can be ensured, and the effect of improving mechanical strength can be efficiently obtained.

The average particle diameter of the core-shell type rubbery polymer particles (G) is preferably 0.05 to 0.90 μm, more preferably 0.08 to 0.85 μm, even more preferably 0.10 to 0.75 μm, and more. More preferably, it is 0.15 to 0.70 μm. In particular, when the particle size is in the range of 0.15 to 0.70 μm, the strength imparting effect of the styrene resin composition is excellent. Furthermore, in the present disclosure, the average particle diameter is measured from a cross-sectional observation image using a transmission electron microscope, as shown in the Examples section below.

The method for producing core-shell type rubbery polymer particles (G) involves producing particles of latex (for example, butadiene rubber latex and/or acrylic rubber latex) containing a rubber component, and then adding styrenic monomer units ( An emulsion polymerization method in which g2-1) and/or (meth)acrylic acid ester monomer units (g2-2) are copolymerized is preferred.

<Inorganic particles (H)>
As a preferred aspect of this embodiment, the styrenic resin composition preferably contains inorganic particles (H). Adding the inorganic particles (H) to the styrenic resin composition serves as a foam nucleating agent during foam molding, and contributes to improving the rigidity of the molded body including the composition and foam sheet.

As the inorganic particles (H), for example, kaolin, mica, silica, calcium carbonate, sodium carbonate, barium carbonate, barium sulfate, calcium sulfate, titanium oxide, aluminum oxide, clay, bentonite, talc, diatomaceous earth, etc. may be used. I can do it. Among them, talc is preferred because it has a rich track record of application to food packaging and is guaranteed to be safe.

The content of the inorganic particles (H) is preferably 0.1 to 7.0 parts by mass, more preferably 0.2 to 6.0 parts by mass, when the total amount of the styrene resin composition is 100% by mass. , more preferably 0.3 to 4.0 parts by mass. By setting the amount in the range of 0.1 to 7.0 parts by mass, a sheet with an expansion ratio suitable for a foam sheet for food packaging can be obtained.

There is no particular restriction on the method of adding the inorganic particles (H) to the styrenic resin composition, but it may be directly blended during extrusion kneading of the styrenic resin composition, or it may be added in advance for ease of industrial production. A resin masterbatch containing inorganic fine particles (H) at a known high concentration may be prepared and added.

<Monohydric alcohol having 10 or more carbon atoms>
In this embodiment, the monohydric alcohol having 10 or more carbon atoms (hereinafter also simply referred to as alcohol) is an optional component, suppresses gelation of the styrene-unsaturated carboxylic acid resin (A) during molding, and provides a good It contributes to improving the appearance of the styrenic resin composition and the molded article made of the styrene resin composition. The content of the monohydric alcohol having 10 or more carbon atoms is 0.01 to 1.0% by mass, preferably 0.03 to 0% by mass, based on the total amount (100% by mass) of the styrenic resin composition. .8% by weight, more preferably 0.05 to 0.6% by weight, even more preferably 0.07 to 0.5% by weight. By setting the content of 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, and 1 By controlling the content to .0% by mass or less, a decrease in heat resistance and generation of odor can be suppressed. By controlling the content of the monohydric alcohol having 10 or more carbon atoms to 0.07 to 0.5% by mass, a sufficient gel-suppressing effect can be obtained without particularly reducing heat resistance.

Monohydric alcohols having 10 or more carbon atoms are alcohols having 10 or more carbon atoms that contain one hydroxyl group, and may also contain heteroatoms 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 even more preferably 18 or more and 50 or less. The monohydric alcohol having 10 or more carbon atoms may be contained in a styrene resin composition or a molded article made of a styrene 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 the (meth)acrylic resin (B). By this, monohydric alcohol may remain in the final product resin composition, or when kneading the styrene-unsaturated carboxylic acid resin (A) and (meth)acrylic resin (B). It may also be contained by adding it to and mixing it in an extruder.

In this embodiment, the boiling point of the monohydric alcohol having 10 or more carbon atoms is preferably 260°C or higher, more preferably 270°C or higher, even more preferably 290°C or higher. If the boiling point of the alcohol is less than 260°C, the volatility will be high and there is a tendency for an off-odor 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.

The polyoxyethylene alkyl ethers are preferably compounds represented by the following general formula (2).
(In the above general formula (2), R is an alkyl group having 12 to 20 carbon atoms, and X represents the average addition number of ethylene oxide and is an integer of 1 to 15.)
Specific product names of preferred alcohols include "Fine Oxocol 180" manufactured by Nissan Chemical Co., Ltd. and "Emulgen 109P" manufactured by Kao Corporation.

"Optional additive ingredients"
The styrenic resin composition of the present embodiment contains, in addition to the above-mentioned components (A) to (H) and a monohydric alcohol having 10 or more carbon atoms, various optional additive components commonly used in styrenic resins. They can also be blended to achieve known effects to form a styrenic resin composition. Optional additive components in this embodiment include, for example, stabilizers, higher fatty acid surfactants, antioxidants, ultraviolet absorbers, lubricants, mold release agents, plasticizers, antiblocking agents, antistatic agents, and antifogging agents. or additives such as mineral oil. There are no particular regulations regarding the method of blending, but for example, additives may be added during polymerization and then polymerized, or additives may be mixed in advance in a blender before melt-kneading after polymerization, and then in an extruder or Banbury mixer, etc. Examples include a method of melting and kneading.

Examples of the above antioxidant include octadecyl-3-(3,5-tert-butyl-4-hydroxyphenyl)propionate, 4,6-bis(octylthiomethyl)-o-cresol (product: Irganox 1076), etc. Examples include hindered phenol-based antioxidants, tris(2,4-di-tert-butylphenyl) phosphite (product: Irgafos 176), and other phosphorus-based antioxidants. These stabilizers may be used alone or in combination of two or more as appropriate. There is no particular restriction on the timing of addition, and it may be added during either the polymerization step or the devolatilization step. The stabilizer can also be mixed into the product using mechanical equipment such as an extruder or Banbury mixer.

As a preferred aspect of this embodiment, the styrenic resin composition preferably contains a higher fatty acid surfactant. The addition of a higher fatty acid surfactant can prevent the foam sheet from blocking, and its addition in an appropriate amount contributes to reducing the torque between pellets and stabilizing metering during kneading of the resin composition. Therefore, the content of the higher fatty acid surfactant is preferably in the range of 0.002 to 0.1 parts by mass based on the total amount of the styrene resin composition. The above effects can be obtained, and by setting the amount to 0.1 part by mass or less, it can be prevented from contributing as a gelling agent for the styrene-unsaturated carboxylic acid resin (A).
The higher fatty acid surfactant can be added during the polymerization of each resin, or it can be added during the kneading of the styrene-unsaturated carboxylic acid resin (A) and (meth)acrylic resin (B). good.

The higher fatty acid surfactant is not particularly limited, and examples thereof include stearic acid, calcium stearate, calcium stearate, ethylene bis-stearamide, and among them, ethylene bis-stearamide is preferred.

[Physical properties and properties of styrenic resin composition]
The physical properties and properties of the styrenic resin composition in this embodiment will be described below.

<Composition of styrenic resin composition>
The styrenic resin composition of this embodiment has resin (A) and resin (B), and the total content of resin (A) and resin (B) is based on the entire styrene resin composition. , preferably 65 to 100% by mass, more preferably 75 to 95% by mass.
The styrenic resin composition of this embodiment has resin (A), resin (B), and optional additive components, and the total content of resin (A), resin (B), and optional additive components is , preferably accounts for 70 to 100% by weight, more preferably 80 to 95% by weight, based on the entire styrenic resin composition.
The styrenic resin composition of this embodiment has resin (A), resin (B), and resin (C), and the total content of resin (A), resin (B), and resin (C) is , preferably accounts for 70 to 100% by mass, more preferably 80 to 90% by mass, based on the entire styrenic resin composition.
The styrenic resin composition of the present embodiment includes resin (A), resin (B), resin (C), and optional additive components, and includes resin (A), resin (B), and resin (C). The total content of the styrenic resin composition and any additional components is preferably 85 to 100% by mass, more preferably 90 to 95% by mass, based on the entire styrenic resin composition.
The styrenic resin composition of this embodiment has resin (A), resin (B), and resin (D), and the total content of resin (A), resin (B), and resin (D) is , preferably accounts for 70 to 100% by mass, more preferably 80 to 90% by mass, based on the entire styrenic resin composition.
The styrenic resin composition of the present embodiment includes resin (A), resin (B), resin (D), and optional additive components, and includes resin (A), resin (B), and resin (D). The total content of the styrenic resin composition and any additional components is preferably 85 to 100% by mass, more preferably 90 to 95% by mass, based on the entire styrenic resin composition.
The styrenic resin composition of this embodiment has a resin (A), a resin (B), and an elastomer (E), and the total content of the resin (A), resin (B), and elastomer (E) is , preferably accounts for 70 to 100% by mass, more preferably 80 to 90% by mass, based on the entire styrenic resin composition.
The styrenic resin composition of this embodiment has a resin (A), a resin (B), an elastomer (E), and an optional additive component, and the resin (A), the resin (B), the elastomer (E) The total content of the styrenic resin composition and any additional components is preferably 85 to 100% by mass, more preferably 90 to 95% by mass, based on the entire styrenic resin composition.
The styrenic resin composition of this embodiment has a resin (A), a resin (B), and an elastomer (F), and the total content of the resin (A), resin (B), and elastomer (F) is , preferably accounts for 70 to 100% by mass, more preferably 80 to 90% by mass, based on the entire styrenic resin composition.

The styrenic resin composition of this embodiment has a resin (A), a resin (B), an elastomer (F), and an optional additive component, and the resin (A), the resin (B), and the elastomer (F). The total content of the styrenic resin composition and any additional components is preferably 85 to 100% by mass, more preferably 90 to 95% by mass, based on the entire styrenic resin composition.
The styrenic resin composition of this embodiment has a resin (A), a resin (B), and a core-shell particle (G), and the total content of the resin (A), the resin (B), and the core-shell particle (G) The amount may preferably be 70 to 100% by mass, more preferably 80 to 90% by mass, based on the entire styrenic resin composition.
The styrenic resin composition of the present embodiment includes resin (A), resin (B), core-shell particles (G), and optional additive components, and includes resin (A), resin (B), core-shell particles ( The total content of G) and any additional components may preferably be 85 to 100% by mass, more preferably 90 to 95% by mass, based on the entire styrenic resin composition.
The styrenic resin composition of this embodiment has a resin (A), a resin (B), and an inorganic particle (H), and the total content of the resin (A), the resin (B), and the inorganic particle (G) The amount may preferably be 60 to 100% by mass, more preferably 75 to 98% by mass, based on the entire styrenic resin composition.
The styrenic resin composition of the present embodiment has a resin (A), a resin (B), an inorganic particle (H), and an optional additive component, and includes a resin (A), a resin (B), an inorganic particle ( The total content of H) and any additional components may preferably be 75 to 100% by mass, more preferably 80 to 98% by mass, based on the entire styrenic resin composition.
The styrenic resin composition of the present embodiment includes a resin (A), a resin (B), a resin (D), and an elastomer (E), and includes a resin (A), a resin (B), and a resin (D). The total content of elastomer (E) and elastomer (E) is preferably 70 to 100% by mass, more preferably 85 to 90% by mass, based on the entire styrenic resin composition.
The styrenic resin composition of this embodiment has a resin (A), a resin (B), a resin (D), an elastomer (E), and an optional additive component, and the resin (A), the resin (B) , the resin (D), the elastomer (E) and any additional components preferably account for 85 to 100% by mass, more preferably 90 to 95% by mass, based on the entire styrenic resin composition. It's possible.
The styrenic resin composition of this embodiment has a resin (A), a resin (B), a resin (C), and an elastomer (F), and the resin (A), the resin (B), and the resin (C). The total content of elastomer (F) and elastomer (F) is preferably 70 to 100% by mass, more preferably 85 to 90% by mass, based on the entire styrenic resin composition.
The styrenic resin composition of this embodiment has a resin (A), a resin (B), a resin (C), an elastomer (F), and optional additive components, and the resin (A), the resin (B) , the resin (C), the elastomer (F) and any additional components preferably account for 85 to 100% by mass, more preferably 90 to 95% by mass, based on the entire styrenic resin composition. It's possible.

The styrenic resin composition of this embodiment has a resin (A), a resin (B), a resin (D), and an elastomer (F), and the resin (A), the resin (B), and the resin (D). The total content of elastomer (F) and elastomer (F) is preferably 70 to 100% by mass, more preferably 85 to 90% by mass, based on the entire styrenic resin composition.
The styrenic resin composition of the present embodiment includes resin (A), resin (B), resin (D), elastomer (F), and optional additive components, and includes resin (A), resin (B), and optional additive components. , the resin (D), the elastomer (F), and any additional components preferably account for 85 to 100% by mass, more preferably 90 to 95% by mass, based on the entire styrenic resin composition. It's possible.

The styrenic resin composition of this embodiment has a resin (A), a resin (B), an elastomer (E), and a core-shell particle (G), and has a resin (A), a resin (B), and an elastomer (E). ) and core-shell particles (G) may preferably account for 70 to 100% by mass, more preferably 85 to 90% by mass, based on the entire styrenic resin composition.
The styrenic resin composition of the present embodiment has a resin (A), a resin (B), an elastomer (E), a core shell particle (G), and an optional additive component, and has a resin (A), a resin (B), and an optional additive component. ), elastomer (E), core-shell particles (G), and optional additive components preferably account for 85 to 100% by mass, more preferably 90 to 95% by mass, based on the entire styrenic resin composition. It can be %.

The styrenic resin composition of this embodiment has a resin (A), a resin (B), an elastomer (F), and a core-shell particle (G), and has a resin (A), a resin (B), and an elastomer (F). ) and core-shell particles (G) may preferably account for 70 to 100% by mass, more preferably 85 to 90% by mass, based on the entire styrenic resin composition.
The styrenic resin composition of this embodiment has a resin (A), a resin (B), an elastomer (F), a core shell particle (G), and an optional additive component, and the resin (A) and the resin (B ), the elastomer (F), the core-shell particles (G), and any additional components preferably account for 85 to 100% by mass, more preferably 90 to 95% by mass of the entire styrenic resin composition. It can be %.

<First molecular weight component of 10,000 or less>
The styrene resin composition of this embodiment has the above resin (A) and the above resin (B), and (meth)acrylonitrile-diene-styrene resin (C), which is blended as necessary, has impact resistance. A group consisting of styrene resin (D), styrene elastomer (E), acrylic elastomer (F), core-shell particles (G), inorganic particles (H), monohydric alcohol having 10 or more carbon atoms, and optional additive components. It may contain one or more selected from. The styrenic resin composition of the present embodiment essentially contains resin (A) and resin (B), and optionally includes a polymer matrix (C1), a polymer matrix (D1), and a styrene elastomer (E ), an acrylic elastomer (F), a monohydric alcohol having 10 or more carbon atoms, and an optional additive component. have
In the matrix polymer portion of this embodiment, when the matrix polymer portion is divided into a molecular weight component with a molecular weight of 10,000 or less (= first molecular weight component) and a molecular weight component with a molecular weight of more than 10,000 (= second molecular weight component), The first molecular weight component of 10,000 or less is preferably within the range of 0.5 to 3.0% by mass based on the total amount of the styrenic resin composition. The range is more preferably from 0.7 to 2.6% by weight, even more preferably from 0.9 to 2.5% by weight, and most preferably from 1.0 to 2.1% by weight. If the amount of the first molecular weight component of 10,000 or less is less than 0.5% by mass, the elongational viscosity of the molten resin will increase and the moldability will decrease. On the other hand, if the amount of the first molecular weight component of 10,000 or less exceeds 3.0% by mass, the mechanical strength of the molded article will decrease due to the excessive presence of the low molecular weight component. By adjusting the amount of the first molecular weight component of 10,000 or less to 0.5 to 3.0% by mass, it is possible to obtain a styrenic resin composition that provides a foamed extruded sheet with excellent both mechanical strength and moldability. .
The amount of the first molecular weight component with a molecular weight of 10,000 or less is determined from the molecular weight distribution obtained by measuring the molecular weight in terms of standard polystyrene using gel permeation chromatography (GPC) using a calibration curve method using standard polystyrene. , the proportion of components having a molecular weight of 10,000 or less in the entire composition.

<Vicat softening temperature>
In this embodiment, the Vicat softening temperature of the styrenic resin composition is preferably 105°C or higher, more preferably 109°C or higher, even more preferably 112°C or higher. By setting the Vicat softening temperature to 105°C or higher, sheets and containers that can be used for cooking in general microwave ovens of around 500W can be obtained, and by setting the softening temperature to 112°C or higher, sheets and containers can be obtained that can be used for cooking in microwave ovens of 1000W or higher placed in convenience stores, etc. It can withstand cooking in high-power commercial microwave ovens. The Vicat softening temperature can be measured in accordance with ISO306 under the conditions of a load of 50 N and a temperature increase rate of 50° C./h.

<Content of conjugated diene monomer units>
In the present embodiment, the content of the conjugated diene monomer unit contained in the styrenic resin composition is preferably 0 to 10% by mass, more preferably 0.3 to 10% by mass, based on the entire styrene resin composition. It ranges from 5.0% by weight, even more preferably from 0.5 to 4.8% by weight, and most preferably from 0.6 to 4.0. A composition with an excellent balance between low-temperature impact strength and rigidity by setting the content of conjugated diene monomer units in the range of 0.6 to 4.0% by mass, and a molded article obtained by molding the composition. , sheets, and containers can be obtained.
Note that, as described above, the conjugated diene monomer unit is a general term for the conjugated diene monomer (c2), the conjugated diene monomer (d2), and the conjugated diene monomer (e2).

<(Meth)acrylic acid monomer or (meth)acrylic acid ester monomer in styrenic resin composition>
In this embodiment, the content of all (meth)acrylic acid monomer units contained in the styrenic resin composition is 2 to 20% by mass with respect to the total amount (100% by mass) of the styrenic resin composition. The content is preferably 3 to 15% by weight, more preferably 4 to 13% by weight, even more preferably 5 to 10% by weight, and most preferably 6 to 8% by weight. 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, the above-mentioned content of all (meth)acrylic acid monomers refers to the total amount of all (meth)acrylic acid monomer units present in the styrenic resin composition. The content of (meth)acrylic acid monomer units in (B) and other components (resin (C), resin (D), elastomer (F), core-shell particles (G), and optional additive components) converted.

In the present embodiment, the content of all (meth)acrylic acid ester monomer units contained in the styrenic resin composition is 6 to 55% by mass with respect to the total amount (100% by mass) of the styrenic resin composition. The content is preferably from 10 to 52% by weight, more preferably from 17 to 47% by weight, and most preferably from 25% by weight. When the content of the (meth)acrylic acid ester monomer in the entire composition is within the above range, a sufficient effect of improving mechanical strength can be obtained.
Note that the content of all (meth)acrylic acid ester monomers refers to the total amount of all (meth)acrylic acid ester monomer units present in the styrenic resin composition, so , (meth) in the resin (B) and other components (resin (C), rubbery polymer particles (D), resin (E), elastomer (G), core shell particles (G) and optional additive components) The content of each acrylic acid ester monomer unit is also converted.

By controlling the content of all (meth)acrylic acid monomer units and all (meth)acrylic acid ester monomer units contained in the styrenic resin composition within the above range, the (meth)acrylic acid monomer units It is possible to obtain the effect of improving heat resistance depending on the mer unit, and as a result, it is possible to obtain a styrenic resin composition having excellent heat resistance, and a foam sheet and a container formed by molding the same.

<Content of styrene component in styrenic resin composition>
The styrenic resin composition in this embodiment contains a styrene component. The styrene component here refers to the styrene monomer (unit) (a1) and other components (resin (B), resin (C), rubbery polymer particles (D), resin (E), elastomer (F), core-shell particles (G), and optional additive components) is a general term for styrenic monomers (units) that can be contained in core-shell particles (G) and optional additive components.
The styrenic resin composition in this embodiment has a content of styrene components (total styrene monomers (units)) of 45 to 85% by mass based on the total amount (100% by mass) of the styrene resin composition. The content is preferably from 55 to 83% by mass, and even more preferably from 58 to 80% by mass. When it is in the range of 45 to 85, a styrenic resin composition with an excellent balance of moldability and heat resistance can be obtained.

A preferable aspect of the styrenic resin composition in this embodiment is that the content of styrenic monomer units is 45 to 85% by mass with respect to the total amount (100% by mass) of the styrenic resin composition, and ) The content of acrylic acid monomer units is 2 to 20% by mass, and the content of (meth)acrylic acid ester monomer units is 6 to 55% by mass. Further, in another preferred embodiment, the content of the styrene monomer unit is 45 to 72% by mass with respect to the total amount (100% by mass) of the styrenic resin composition, and the content of the (meth)acrylic acid monomer is 45 to 72% by mass. The content of the units is 5 to 10% by mass, the content of (meth)acrylic acid ester monomer units is 17 to 50% by mass, and the content of conjugated diene monomer units is 0.5 to 10% by mass. It is 10% by mass.

The average particle diameter of all the rubbery polymer particles contained in the styrenic resin composition of this embodiment is preferably 0.08 to 5.0 μm, more preferably 0.10 to 4.0 μm. It is preferably from 0.20 to 2.5 μm, even more preferably from 0.25 to 2.0 μm.
When the average particle diameter of all the rubbery polymer particles, so-called apparent rubbery polymer particles, is within the above range, the strength imparting effect to the styrenic resin composition is maximized.
The total amount of all rubber-like polymer particles (including the encapsulated resin) in the entire styrenic resin composition of this embodiment is 0.5 to 8.0 with respect to the total amount (100% by mass) of the styrenic resin composition. It is preferably 0.6% to 6.5% by mass, even more preferably 0.7% to 5.5% by mass, and 0.8% to 4.5% by mass. Even more preferably.
When the content of all the rubbery polymer particles contained in the styrenic resin composition is within the above range, the effect of imparting strength to the styrene resin composition is maximized.
In addition, the content of all rubbery polymer particles means that each rubbery polymer particle, that is, the ABS rubbery polymer particle (C2) and the rubbery polymer particle (D2) each contains other than conjugated diene monomer units. (polymer domain phase), components other than the conjugated diene monomer unit (polymer domain phase) are also included in the content of the total rubbery polymer particles.
The content of the conjugated diene monomer (=rubber amount) in all the rubbery polymer particles in the entire styrenic resin composition of this embodiment is as follows with respect to the total amount (100% by mass) of the styrenic resin composition: The range is preferably from 0 to 10% by weight, more preferably from 0.3 to 5.0% by weight, even more preferably from 0.5 to 4.8% by weight, and most preferably from 0.6 to 4.0. It is possible to obtain a styrenic resin composition with an excellent balance of strength and rigidity, and molded bodies, sheets, and containers formed by molding the composition.
The total rubbery polymer particles include rubbery polymer particles (C2) and rubbery polymer particles (D2).

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

<Foam extrusion sheet>
The extruded foamed sheet of the present invention can be produced by the conventionally known so-called extruded foaming method. That is, using an extruder, the base resin and various additives such as a foaming nucleating agent (bubble regulator), which will be described later, added as necessary are heated, melted, and kneaded, and a physical foaming agent is press-injected. After further kneading, the foamable molten resin adjusted to an appropriate resin temperature is extruded through a die under atmospheric pressure and foamed.

In the present embodiment, when forming a foamed extruded sheet, a commonly used substance can be used as a foaming agent during extrusion and foaming. As the foaming agent, normal butane, isobutane, pentane, chlorofluorocarbon, carbon dioxide, water, diethyl ether, etc. can be used, and butane, isobutane, diethyl ether, etc. are suitable, and two or more of the above foaming agents are used in combination. You can also. The amount of the foaming agent added during foam molding is preferably 0.5 to 8.0 parts by mass, more preferably 1.0 to 6.0 parts by mass, based on 100 parts by mass of the styrene resin composition to be foamed. Parts by weight, more preferably 2.0 to 5.0 parts by weight, even more preferably 2.5 to 4.5 parts by weight. In particular, when the amount is in the range of 2.0 to 5.0 parts by mass, the plasticizing effect and foamability of the resin are excellent.

In this embodiment, when forming an extruded foam sheet, a commonly used substance can be used as a foam nucleating agent during extrusion foaming. For example, the talc, silica, mica, etc. mentioned above as the inorganic particles (H) can be used. The content of the foaming nucleating agent is preferably 0.1 to 7.0 parts by mass, more preferably 0.2 to 6.0 parts by mass, and more preferably 0.2 to 6.0 parts by mass, when the total amount of the styrenic resin composition is 100 parts by mass. More preferably, it is 0.3 to 4.0 parts by mass. By setting the amount in the range of 0.1 to 7.0 parts by mass, a sheet with an expansion ratio suitable for a foam sheet for food packaging can be obtained. The foaming nucleating agent may be added directly, or a masterbatch may be used in which resin pellets in which a high concentration foaming nucleating agent is dispersed in advance by extrusion kneading are added.

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

In this embodiment, the apparent density of the extruded foam sheet is preferably 0.05 to 0.30 g/cm ³ , more preferably 0.06 to 0.20 g/cm ³ , and even more preferably 0.07 g/cm 3 . ~0.10g/ ^cm3 . In particular, by setting the amount in the range of 0.07 to 0.10 g/cm ³ , it is possible to provide a foamed extruded sheet with an excellent balance between strength and productivity.

In the present embodiment, the basis weight of the extruded foam sheet is preferably 70 to 300 g/m ² , more preferably 75 to 250 g/m ² , even more preferably 80 to 200 g/m ² , even more preferably 90 to 200 g/m 2 It is 150g/ ^m2 . In particular, by setting the amount in the range of 80 to 200 g/m ² , it is possible to provide an extruded foam sheet with an excellent balance between strength and productivity.

In this embodiment, the foaming ratio of the extruded foam sheet is preferably 5 to 18 times, more preferably 6 to 17 times, even more preferably 7 to 16 times, even more preferably 8 to 15 times.

In this embodiment, the closed cell ratio of the foamed extruded sheet determined according to the method of JIS K7138:2006 is preferably 75% or more, more preferably 80% or more, still more preferably 83% or more, and 86% or more. Even more preferred. In particular, by setting the closed cell ratio to 80% or more, there are fewer brittle open cells, so a foamed sheet with excellent strength can be obtained.

In the present embodiment, the average cell diameter of the extruded foam sheet is preferably in the range of 200 to 500 μm, more preferably in the range of 250 to 450 μm. By setting the thickness in the range of 200 to 500 μm, it is possible to provide an extruded foam sheet with an excellent balance between strength and productivity.

The foamed extruded sheet of the present invention may be multilayered by further laminating films. The type of film used may be one used for general polystyrene. Examples include PP (polypropylene)/PS (polystyrene) dry laminated films, and the thickness of the laminated film is preferably 5 to 200 μm, more preferably 10 to 150 μm, even more preferably 20 to 100 μm. A range of 20 to 100 μm provides an excellent balance of weight reduction, strength, and oil-resistant reinforcement.
The preferred foam extrusion sheet of this embodiment includes a foam layer of a styrenic resin composition, a polystyrene layer provided on at least one surface of the foam layer, and a polypropylene layer provided on the cotton of the polystyrene layer. It is a laminate having . With this structure, the polypropylene layer is provided as the outermost layer that can come into contact with foods, etc., so it is possible to provide a container with excellent oil resistance. Furthermore, since the foam layer of the styrene resin composition contains styrene monomer units, it is possible to provide a container with excellent compatibility and adhesion with the polystyrene layer.

[Secondary molded product]
A molded article obtained by thermoforming a foamed sheet is suitably used as a container for microwave-heated foods. Examples of thermoforming methods include vacuum forming and pressure forming. Such a thermoforming method is a preferred method because containers can be obtained continuously in a short period of time. In addition, when thermoforming the laminated sheet obtained by thermocompression-bonding the above-mentioned laminate film, it is preferable to mold so that a polyolefin resin film having excellent oil resistance is located inside the resulting molded product.

Next, the present invention will be explained 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 resins, extruded sheets, etc. in Examples and Comparative Examples are as follows.

[Composition evaluation of each resin and resin composition]
(1) Measurement of the content of each monomer unit Measurement of the content of each monomer unit contained in the resin compositions prepared in Examples and Comparative Examples by pyrolysis GC/MS under the following conditions I did this.
Sample preparation: Each resin and the resin composition prepared in Examples and Comparative Examples were dissolved in chloroform at 5% by mass, 20 μL was dropped into a sample cup, and vacuum-dried at 80° C. for 24 hours.
Measurement conditions Pyrolysis unit Equipment: Frontier Lab PY-3030D
Heating furnace temperature: 600℃
G.C.
Equipment: Shimadzu GCMS-GP2020NX
Column: Ultra Alloy-CW
(Length 30m, film thickness 0.25μm, diameter 0.25mmφ)
Column temperature: held at 40°C for 3 minutes, heated at 10°C/min, and held at 250°C for 10 minutes.
Inlet temperature: 250℃
Detector temperature: 230℃
Split ratio: 1/300
Carrier gas: Helium Detection method: Mass spectrometer (MSD)
In addition, when detecting each monomer peak, in order to avoid overlapping of peaks and saturation of peak intensity, pretreatment such as sample dilution rate, column used, and detection conditions may be adjusted as appropriate.
(2) Measurement of the content of monohydric alcohol having 10 or more carbon atoms in each resin composition The content of monohydric alcohol having 10 or more carbon atoms in the entire resin composition prepared in Examples and Comparative Examples was determined by It was measured using gas chromatography under the following conditions.
Sample preparation: After dissolving 1.0 g of resin in 5 mL of methyl ethyl ketone, 5 mL of hexane containing p-diethylbenzene adjusted to 200 μg/g as a standard substance was added to reprecipitate the polymer component, collect the supernatant liquid, and add the measurement solution. And so.
Measuring equipment: Agilent 6850 series GC system Detector: FID
Column: DB-WAX
Length: 60m
Film thickness: 0.50μm
Diameter: 0.320mmφ
Injection volume: 1μL
Split ratio: 50:1
Column temperature: Hold at 100°C for 5 minutes → Raise the temperature to 130°C at 10°C/min → Raise the temperature to 180°C at 10°C/min → Hold at 180°C for 10 minutes → Raise the temperature to 220°C at 20°C/min → Hold at 220℃ for 10 minutes Inlet temperature: 230℃
Detector temperature: 300℃
Carrier gas: Helium When detecting the peak of monohydric alcohol (C) having 10 or more carbon atoms, in order to avoid overlapping other peaks and saturation of the peak intensity, pretreatment such as dilution of the sample and use of The column to be used and the detection conditions may be adjusted as appropriate.
[Characteristic evaluation of each resin and resin composition]
(3) Measurement of the amount of the first molecular weight component of 10,000 or less The ratio of the first molecular weight component of 10,000 or less of each resin and resin composition manufactured in the Examples and Comparative Examples ) and the standard polystyrene equivalent molecular weight was measured by the calibration curve method using standard polystyrene under the following conditions.
Measuring equipment: Tosoh HLC-8220
Separation column: Two Tosoh TSK gel Super HZM-H (inner diameter 4.6 mm) connected in series Guard column: Tosoh TSK guard column Super HZ-H
Measurement solvent: Tetrahydrofuran (THF)
Sample concentration: 5 mg of the measurement sample was dissolved in 10 mL of solvent, and filtered through a 0.45 μm filter.
Injection volume: 10μL
Measurement temperature: 40℃
Flow rate: 0.35 mL/min Detector: Differential refractometer To create the calibration curve, 11 types of TSK standard polystyrene manufactured by Tosoh (F-850, F-450, F-128, F-80, F-40, -20, F-10, F-4, F-2, F-1, A-5000) were used. A calibration curve was created using a linear linear approximation formula.

(4) Measurement of Vicat Softening Temperature The Vicat softening temperature of each resin and resin composition manufactured in Examples and Comparative Examples was measured in accordance with ISO306. The load was 50N, and the temperature increase rate was 50°C/h. Products with a Vicat softening temperature of over 105°C have excellent dimensional stability under temperatures assumed when heating sheet molded products and container molded products in a microwave, and those with a Vicat softening temperature of over 115°C have almost no dimensional change at practical temperatures. There was a tendency not to.

(5) Measurement of Melt Tension The melt tension (gf) of each resin and resin composition manufactured in Examples and Comparative Examples was measured under the following conditions.
Measuring equipment: Malvern capillary rheometer RH10
Capillary die: 2mmφ x 20mmL
Measurement temperature: 220℃
Piston descending speed: 8.1mm/min
Winding speed: 3.1m/min
Drying conditions: Each resin and resin composition was dried at 80° C. for 2 hours before measurement.
After drying the styrenic resin composition of the example and the resin composition obtained in the comparative example at 80° C. for 2 hours or more, about 30 g of each was put into a cylinder, and the piston was lowered at a rate of 8.1 mm/min. After 6 minutes had passed since the sample was introduced, the strand coming out of the die was attached to a booley and a winding drum, and winding was started at 3.0 m/min. Ten minutes after the sample was introduced, the winding speed was increased to 3.1 m/min and melt tension measurement was started. The melt tension value was measured 100 times in 5 minutes, and the average value was taken as the melt tension (MT) measurement value.

(6) Measurement of extensional viscosity The extensional viscosity (EV) of each resin and styrene resin composition manufactured in Examples and Comparative Examples was measured based on the following viscoelasticity measurement.
Device name: Viscoelasticity measurement device ARES-G2 manufactured by TA Instruments
Measurement system: ARES-EVF option Test piece dimensions: length 20mm, width 10mm, thickness 0.8mm
Elongation strain rate: 1.0/s
Measurement temperature: 160℃
Measurement atmosphere: Nitrogen flow Preheating time: 2 minutes Pre-elongation strain rate: 0.03/s
Pre-extension length: 0.295mm
Relaxation time after preliminary elongation: 2 minutes After drying the styrenic resin composition of the example and each resin composition produced in the comparative example at 80°C for 2 hours or more, a 50-ton compression molding machine manufactured by Soken Co., Ltd. (hereinafter referred to as A test piece with a thickness of 0.7 mm was molded using a compression molding machine. The molded test pieces were stored in a desiccator until measurement to prevent moisture absorption. The test piece was attached to a roller with a distance of 18 mm between the fasteners, and after the temperature stabilized at the measurement temperature, it was left standing for 2 minutes to preheat. After preheating, preliminary elongation was performed under the above conditions, and the sample was allowed to stand for 2 minutes to relax the stress generated during the preliminary elongation, and the elongation viscosity was measured. The measured value when the Henkey strain was 0.5 was taken as the elongational viscosity (EV) measured value.

(7) Evaluation of surface impact of solid sheet After drying the styrenic resin composition of the example and each resin composition manufactured in the comparative example at 80°C for 2 hours or more, a 0.7 mm thick solid sheet was formed using a compression molding machine. I created a sheet. After cutting into a size of 8×8 cm, the film impact was measured using a Toyo Seiki film impact tester (No. 195), and the n8 average was taken as the value.

(8) Evaluation of deep drawability of non-foamed sheets After drying the styrene resin compositions of Examples and each resin composition produced in Comparative Examples at 80°C for 2 hours or more, a compression molding machine was used to form a 0.7 mm sheet. A thick solid sheet was created. A test piece with a size of 250 mm long x 250 mm wide was cut out from the obtained sheet, and using a Soken sheet container molding machine, the test piece was sandwiched between the fixed frames of this sheet molding machine, and the average temperature of the heater was set to 230 ° C. , the ambient temperature was set to 120° C., and the mixture was heated for 20 seconds. Next, vacuum forming was performed by sliding the fixed frame together into a bowl container mold (temperature: 40° C.) with a diameter of 10 cm and a depth of 6 cm, to form 20 molded bodies at a time. It was visually confirmed whether or not tearing had occurred on the side surface of this molded body, and the number of molded bodies that could be molded without tearing was taken as an index of deep drawability.

[Characteristics evaluation of extruded foam sheet]
(9) Basis weight of extruded foam sheet (g/m ² )
A 0.10 x 0.10 m sheet section was prepared by removing 20 mm from both ends of the extruded foam sheets produced in Examples and Comparative Examples. The mass of each section was measured, and the mass converted per 1.0 m ² was calculated as basis weight (g/m ² ).

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

(11) Measurement of heat resistance of extruded foam sheets The extruded foam sheets produced in Examples and Comparative Examples were cut into strips of 10 cm x 1.5 cm with the MD direction as the long side, and placed in an oven set at 110° C. for 60 minutes. After that, the deformation of the foamed extruded sheet was measured, and the heat resistance was evaluated based on the thermal deformation as follows.
Specifically, for the above-mentioned dimensional change, the amount of change in length of 10 cm before and after thermal deformation was measured using the following formula (I), and the n5 average was taken as the value.
Formula (I): Dimensional change (%) = (Length in the MD direction of the foam sheet after being placed in the oven for 60 minutes - Length in the MD direction of the foam extruded sheet before being placed in the oven)/Length in the MD direction of the foam sheet before being placed in the oven) Length of extruded foam sheet in MD direction ◎: No dimensional change 〇: Dimensional change 1% or less △: Dimensional change 1% or more and 3% or less ×: Dimensional deformation 3% or more

(12) Evaluation of deep drawing formability of foamed sheets A test piece with a size of 250 mm in length x 250 mm in width was cut from the extruded foamed sheets produced in Examples and Comparative Examples, and heated to 23 ± 3°C and relative humidity of 50 ± 5%. and left for 20 days. Thereafter, using a sheet container molding machine manufactured by Soken, the foamed sheet was sandwiched between the fixed frames of the sheet molding machine, the average temperature of the heater was set to 230°C, and the ambient temperature was set to 160°C, and heating was performed for 15 seconds. Next, vacuum forming was performed by sliding the fixed frame together into cup-shaped molds (temperature: 40° C.) with a diameter of 10 cm and different depths of 3 cm or 6 cm, and 100 molded objects were molded at a time. It was visually confirmed whether or not tearing had occurred on the side surface of this molded body, and the number of molded bodies that could be molded without tearing was taken as an index of deep drawability.

[Characteristics evaluation of molded products made by secondary molding of foam extrusion sheets]
Using a hot plate molding machine, the extruded foam sheets produced in Examples and Comparative Examples were fitted with an inner fitting lid having a diameter of 200 mm and a height of 45 mm under conditions of a hot plate temperature of 285°C and a heating time of 5.0 seconds. It was molded into a foamable container and subjected to the evaluation described in (13) and (14) below.

(13) Impact strength of foam container A test piece measuring 80 mm in length x 80 mm in width is cut from the center of the bottom of the foam container, and an impact is applied to the outer part of the container using a Toyo Seiki film impact tester (No. 195). Film impact was measured based on the orientation, the n8 average was taken as the value, and evaluation was made from the following viewpoints.
◎: 4.0 kg or more ○: 2.0 kg/cm or more to 4.0 kg/cm or less ×: Less than 2.0 kg/cm Containers weighing less than 2.0 kgf tended to have cracks in the transportation container.

(14) Appearance of foam container The condition of the surface of the foam container was visually observed. A molded product with no unevenness or roughness observed on its surface was judged to have a good appearance, and the number of molded products with a good appearance out of 100 molded products was used as an evaluation index.

[Preparation of each resin and manufacturing example of styrene resin composition]
The preparation of each resin and the specific manufacturing method of the styrene resin composition will be described below.
<Production example of styrene-unsaturated carboxylic acid resin (A)>
-Preparation of styrene-unsaturated carboxylic acid resin (A-1)-
65.5 parts by mass of styrene, 3.3 parts by mass of methyl methacrylate, 5.8 parts by mass of methacrylic acid, 22.9 parts by mass of ethylbenzene, 2.5 parts by mass of 2-ethyl-1-hexanol, and 1,1-bis( A polymerization raw material composition solution consisting of 0.027 parts by mass of t-butylperoxy)cyclohexane was supplied at a rate of 0.8 liters/hour to a complete mixing reactor with a capacity of 3.6 liters, and then unreacted monomers were The mixture was continuously supplied to a devolatilization device connected to a single-screw extruder for removing volatile components such as polymerization solvent. The polymerization temperature of the complete mixing reactor was 130°C. The temperature of the single-screw extruder was set at 210 to 230°C and the pressure was set at 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. The physical properties of the resin (A-1) obtained by the above analysis method are shown in Table 1 below.

-Preparation of styrene-unsaturated carboxylic acid resin (A-2)-
Resin (A-2) was prepared in the same manner as for resin (A-1) using the feed amounts of each monomer listed in Table 1 and the polymerization conditions used in the preparation of resin (A-1). did. Table 1 shows the composition and physical properties of the resin (A-2) obtained.

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

<Production example of (meth)acrylic resin (B)>
-Preparation of (meth)acrylic resin (B-1)-
A suspension agent was prepared by putting 2 kg of water, 65 g of tribasic calcium phosphate, 39 g of calcium carbonate, and 0.39 g of sodium lauryl sulfate into a 5 L container equipped with a stirrer, and mixing and stirring them. 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 the temperature was constant, 1.52 kg of methyl methacrylate, 0.22 kg of methyl acrylate, 0.99 g of lauroyl peroxide, 4.93 g of n-octyl mercaptan, and The above suspending agent was added. Thereafter, suspension polymerization was carried out while maintaining the temperature at about 80°C, and 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. Next, the polymerization reaction solution was taken out from the 60 L reactor and passed through a sieve with a sieve opening of 1.7 mm to remove giant aggregates, and then the aqueous layer and solid matter were separated using a Buchner funnel to obtain bead-shaped polymers. The bead-like polymer was washed and dehydrated five times with about 20 L of distilled water on a Buchner funnel, dried, and pelletized using a single-screw extruder to produce (meth)acrylic resin as pellets. A resin (B-1) (hereinafter referred to as resin (B-1); the same applies to other (meth)acrylic resins (B-2) and (B-3)) was obtained.

-Preparation of (meth)acrylic resins (B-2), (B-3) and (B-5)-
Using the feed amount of each monomer listed in Table 2 and the polymerization conditions for preparing the resin (B-1), the (meth)acrylic resin (B -2), (B-3) and (B-5) were prepared. Table 2 shows the composition and physical properties of the resulting resins (B-2), (B-3) and (B-5).

-Preparation of (meth)acrylic resin (B-4)-
Ethylene, methyl methacrylate, and the polymerization initiator t-butyl-peroxy-2-ethylhexanoate are fed into a tubular reactor, and then a unit is used to remove volatile components such as unreacted monomers and polymerization solvent. It was continuously fed to a devolatilization device connected to a shaft extruder. The gas concentration of methyl methacrylate in the feed gas was 5.5% by mass. The polymerization temperature in the tubular reactor was 220°C. The temperature of the single-screw extruder was set at 150 to 170°C and the pressure was set at 10 torr to devolatilize volatile components such as unreacted monomers and polymerization solvent. The resin was collected as pellets. The physical properties of the resin (B-4) obtained by the above analysis method are shown in Table 2 below.

-Preparation of (meth)acrylic resin (B-6)-
As the resin (B-6) in this example, ARUFON UP-1021 manufactured by Toagosei Co., Ltd. was used.

-Preparation of (meth)acrylic resin (B-7)-
Acrift WH206-F manufactured by Sumitomo Chemical was used as the resin (B-7) in this example.

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

<Production example of (meth)acrylonitrile-diene-styrene resin (C)>
The outline of the method for preparing the (meth)acrylonitrile-diene-styrene resin (C) used in this example is to first prepare butadiene-styrene-acrylonitrile graft copolymer particles (rubber-like polymer particles (C2)) at a high concentration. A resin (C2-1) containing a separately prepared styrene-acrylonitrile copolymer (C1-1) and a resin (C2-1) containing a high concentration of the butadiene-styrene-acrylonitrile graft copolymer particles was produced. This method involves kneading and diluting 1) and adjusting the concentrations of the rubbery polymer particles (C2) and the polymer matrix (C1) to desired values. A specific example of the preparation method will be described below.

-Preparation of (meth)acrylonitrile-diene-styrene resin (hereinafter referred to as ABS resin) (C-1)-
After adding 0.1 parts by mass of tertiary decyl mercaptan and 23 parts by mass of deionized water to 122 parts by mass of polybutadiene rubber latex (average particle diameter 0.280 μm, solid content 37% by mass), and replacing the gas phase with nitrogen. , the temperature was raised to 55°C.Then, while raising the temperature to 70°C over 1.5 hours, 14 parts by mass of acrylonitrile, 37 parts by mass of styrene, 0.5 parts by mass of tert-decyl mercaptan, and 0 part of cumene hydroperoxide were added. For a monomer mixture consisting of .15 parts by mass, 50 parts by mass of deionized water, 0.2 parts by mass of sodium formaldehyde sulfoxylate, 0.004 parts by mass of ferrous sulfate, and 0 parts by mass of ethylenediaminetetraacetic acid disodium salt. An aqueous solution containing 0.04 parts by mass of cumene hydroperoxide was added over 4 hours.After the addition was complete, 0.02 parts by mass of cumene hydroperoxide was added, and the polymerization reaction was continued for another 1 hour while controlling the reaction tank at 70°C. Completed.
The mixture of the styrene-acrylonitrile copolymer (C1-1) and the butadiene-styrene-acrylonitrile graft copolymer (C2-1) thus obtained was added with a silicone resin antifoaming agent (Momentive Performance Materials). A phenolic antioxidant emulsion (manufactured by Chukyo Yushi Co., Ltd., product name L-673) was added. Thereafter, deionized water was added to adjust the solid content concentration to 10% by mass, and the mixture was heated to 70°C. Thereafter, an aqueous aluminum sulfate solution was added to solidify the mixture, and solid-liquid separation was performed using a screw press. The water content at this time was 10% by mass. This was dried to obtain a resin (C2-1) containing butadiene-styrene-acrylonitrile graft copolymer particles (C2-1) at a high concentration.
As a result of compositional analysis, the composition ratio of the resin (C2-1) was 17% by mass of acrylonitrile, 45% by mass of butadiene, and 38% by mass of styrene. Also, the butadiene-styrene-acrylonitrile graft copolymer took the form of particles like the polybutadiene rubber latex, and the average particle size was 0.30 μm.
On the other hand, a monomer mixture consisting of 63 parts by mass of styrene, 22 parts by mass of acrylonitrile, and 15 parts by mass of ethylbenzene was continuously fed into a complete mixing reactor equipped with a stirrer, and a polymerization reaction was carried out at 150°C for a residence time of 2 hours. I did it. The obtained polymerization solvent was continuously supplied to an extruder, and unreacted monomers and solvent were recovered by a devolatilizing extruder to obtain a styrene-acrylonitrile copolymer (C1-1). As a result of compositional analysis using a Fourier transform infrared spectrophotometer (FR-IR) (manufactured by JASCO Corporation), the composition of the copolymer (C1-1) was found to be 30% by mass of acrylonitrile and 70% by mass of styrene. Met.
Resin (C2-1) containing a high concentration of butadiene-styrene-acrylonitrile graft copolymer particles (rubber-like polymer particles (C2)) obtained by the above procedure and styrene-acrylonitrile copolymer (C1-1) ) was extrusion-kneaded using a twin-screw extruder and pelletized to obtain ABS resin (C-1) as a pelletized ABS resin.

-Preparation of ABS resin (C-2)-
After adjusting the feed amount of each monomer and polymerization conditions and preparing a resin (C2-1) by the same procedure as the above ABS resin (C-1), 90 parts by mass of ABS resin and styrene-acrylonitrile-N- ABS resin (C-2) was obtained as a pellet-shaped ABS compound resin by extrusion-kneading and pelletizing 10 parts by mass of a phenylmaleimide copolymer using a twin-screw extruder. Table 3 shows the composition and physical properties of the obtained ABS resin (C-2).

<Production example of impact-resistant styrenic resin (D)>
-Preparation of impact resistant styrenic resin (D-1)-
Using a polymerization apparatus consisting of three laminar flow reactors (1.5 liters) each equipped with a stirrer connected in series, followed by a two-stage vented extruder, high-impact styrene resin (D-1) was produced. ) (hereinafter referred to as resin (D-1)) was produced. In a raw material tank equipped with a stirrer, 82.4 parts by mass of styrene, 9.0 parts by mass of ethylbenzene, 8.6 parts by mass of high-cis butadiene rubber 13HB manufactured by Ube Industries, Ltd. as a rubbery polymer (D2), and 1,1-bis( After adding 0.02 parts by mass of t-butylperoxy)cyclohexane and dissolving the rubber component with a stirrer, this raw material solution was supplied to the reactor at a capacity of 0.75 liters/hr, and the first stage reactor was heated. Polymerization was carried out at a temperature of 110 to 120°C, a second stage reactor temperature of 120 to 130°C, and a third stage reactor temperature of 140 to 150°C. Further, the extruder temperature was 210 to 240°C, the degree of vacuum was 3 kPa, and the total solid content in the polymerization liquid discharged from the final reactor was 70.5% by mass. The average particle diameter of the rubbery polymer particles (D2) was controlled by adjusting the rotation speed of the stirrer in the first stage laminar flow reactor to 110 rpm. The obtained impact-resistant styrenic resin (D-1) (hereinafter referred to as resin (D-1). The same applies to other impact-resistant styrenic resins (D-2) and (D-3)). The composition and properties are shown in Table 4.

-Preparation of impact-resistant styrenic resins (D-2) and (D-3)-
Using high-cis butadiene rubber 15HB manufactured by Ube Industries, Ltd. as the rubbery polymer (D2), resin (D-2) and resin (D-3) were prepared with the composition and physical properties shown in Table 4 in the same manner as above. I got it.

-Preparation of impact-resistant styrenic resin (D-4)-
Using styrene and methyl methacrylate as monomers and high-cis butadiene rubber 15HB manufactured by Ube Industries, Ltd. as the rubbery polymer (D2), resin (D-4) was prepared with the composition and physical properties shown in Table 4 in the same manner as above. Obtained at.

<Styrenic elastomer (E) used in Examples>
In the examples of this specification, the styrene-butadiene block copolymer Tuffrene 125 (=styrene elastomer (E-1)) manufactured by Asahi Kasei Corporation was used as the styrene elastomer (E). The characteristics are shown in Table 5 below.

<Acrylic elastomer (F) used in Examples>
In the Examples of this specification, the following three types were used as the acrylic elastomer (F).
Resin (F-1): Clarity LA4285 manufactured by Kuraray Co., Ltd.
Resin (F-2): Clarity LA2270 manufactured by Kuraray Co., Ltd.
Resin (F-3): Clarity LA2250 manufactured by Kuraray Co., Ltd.
Each of the above acrylic elastomers (F) is a poly(methyl methacrylate-b-(n-butyl) acrylate-b-methyl methacrylate) triblock copolymer and has the properties shown in Table 6 below.

<Production example of core-shell type rubbery polymer particles (G)>
-Preparation of rubbery polymer particles (G-1)-
In a pressure-resistant container 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, polyoxyethylene alkyl After charging 0.03 parts by mass of sodium 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 para-menthane hydroperoxide were added, and then 6 parts by mass of sodium formaldehyde sulfoxylate were added. After dropping 1.4 parts by mass of sodium polyoxyethylene alkyl ether phosphate over a period of time, the reaction solution was kept at 50°C for 124 hours at pH 6.5 to 7.5, and the conversion rate was 98% by weight, and the average particle A diene rubber latex having a diameter of 0.18 μm was obtained.
Subsequently, while maintaining the rubber latex obtained above (solid content: about 71 parts) at 60° C., styrene and methyl methacrylate as monomers were added over 1 hour. Simultaneously with the addition of the above monomers, addition of 0.09 parts by mass of t-butyl hydroperoxide and 0.1 parts by mass of sodium formaldehyde sulfoxylate was started, and then the pH of the reaction solution was adjusted to 6.5 to 6.5 parts by mass. 7.5. The entire amount was added over 2 hours while maintaining the temperature at about 60°C. The reaction solution was further held at about 60°C for 1 hour to prepare a graft copolymer latex with an average particle size of 200 nm, and after adding 1 part by mass of Irganox 1076 as an antioxidant, it was coagulated with an aqueous calcium chloride solution. Rubber-like polymer particles (G-1) were obtained as a powder by processing, washing with water, and dehydrating and drying. Table 7 shows the composition and physical properties of the rubbery polymer particles (G-1).

-Preparation of rubbery polymer particles (G-2) and (G-3)-
(G-2) and (G-3) were prepared in the same manner as in (G-1) above using methyl methacrylate and n-butyl acrylate as monomers for the graft chain. Table 7 shows the composition and physical properties of the obtained rubbery polymer particles (G-2) and (G-3).

-Preparation of rubbery polymer particles (G-4)-
(G-4) was prepared in the same manner as (G-1) above using acrylic acid (n-butyl) as a rubber latex monomer. Table 7 shows the composition and physical properties of the obtained rubbery polymer particles (G-4).

-Preparation of rubbery polymer particles (G-5)-
As the resin (G-5) in this example, Metablen W-450A manufactured by Mitsubishi Chemical Corporation was used.

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

<<Manufacture example of styrenic resin composition and foam extrusion sheet>>
Detailed manufacturing methods for the styrenic resin composition and foamed extruded sheet are shown below.
[Example 1]
-Manufacture of styrenic resin composition-
93.0 parts by mass of the resin (A-1) listed in Table 1 was used as the styrene-unsaturated carboxylic acid resin (A), and the resin (B-1) listed in Table 2 was used as the (meth)acrylic resin (B). 7.0 parts by mass and 0.12 parts by mass of Fine Oxocol 180 were dry blended, kneaded and extruded using a twin-screw extruder TEM26SS manufactured by Shibaura Kikai Co., Ltd., and pelletized to obtain a styrene resin composition as pelletized resin. Product [1] 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. The evaluation results of the properties and physical properties of the styrene resin composition [1] are shown in Table 8-1.
-Manufacture of extruded foam sheets-
100 parts by mass of the styrene resin composition [1] obtained above was dry-blended with 1.0 parts by mass of talc (High Filler #12 manufactured by Matsumura Sangyo Co., Ltd.) as inorganic fine particles (H), and an extruder was used. supplied to. The maximum cylinder temperature of the extruder was set at 250°C. 4.0 parts by mass of mixed butane with a mass ratio of isobutane/n-butane of 65/35 as a blowing agent is injected into the melt-kneaded resin composition per 100 parts by mass of the styrenic resin composition [1] to form a cyclic resin composition. It was extruded into a cylindrical shape through a die and foamed. After cooling the obtained cylindrical foam by blowing air thereto, a cooling step was performed using a cooling mandrel, and the cylindrical foam was cut in the extrusion direction to obtain a foamed extruded sheet [1].
Table 8-1 shows the evaluation results of the obtained foamed extruded sheet [1] and the foamed container formed by secondary molding the foamed extruded sheet [1].

[Examples 2 to 36]
Styrenic resin compositions [2] to [36] and foamed extruded sheets [2] to [36] were prepared in the same manner as in Example 1 except that the formulations were changed as shown in Tables 8-1 to 8-4 below. Obtained. Table 8-1 shows the evaluation results of the obtained styrenic resin compositions [2] to [36] and foamed extruded sheets [2] to [36], and the evaluation results of the foamed container made by secondary molding the foamed extruded sheets. ~ Shown in Table 8-4.

[Comparative Examples 1 to 3]
A resin composition and a biaxially stretched sheet were obtained in the same manner as in Example 1, except that the mixing ratio was changed as shown in Table 9 below. Table 9 shows the evaluation results of the obtained resin composition and foam sheet, and the evaluation results of the foam container formed by secondary molding the foam sheet.

The styrenic resin composition obtained by the present invention has excellent heat resistance, transparency, rigidity, heat oil resistance, and appearance. Therefore, the styrenic resin composition of the present invention can be used for extrusion molding, non-foamed sheets or foamed sheets, food packaging containers using them, or injection molded products (electronic product parts, toys, daily necessities, various industrial parts), etc. It can be used in a wide range of applications, and is particularly useful in packaging materials that can be heated in a microwave oven, so it plays a major role in industry.

Claims (13)

50 to 98% by mass of a styrene-unsaturated carboxylic acid resin (A) having a styrene monomer unit (a1) and an unsaturated carboxylic acid monomer unit (a2),
A styrenic resin composition containing more than 0 to 50% by mass of a (meth)acrylic resin (B) having an unsaturated carboxylic acid monomer unit (b1),
The styrenic resin composition has an elongational viscosity (MPa·s) of 0.6 MPa·s or less at a temperature of 160°C, a strain rate of 1.0/s, and a Henky strain of 0.5. The styrenic resin composition according to claim 1, wherein the (meth)acrylic resin (B) has an ethylene monomer unit. The melt tension (gf) of the styrenic resin composition at a temperature of 220° C. and a take-up speed of 3.1 m/min is determined by the melt tension (gf) of the styrenic resin composition at a temperature of 160° C., a strain rate of 1.0/s, and a Henky strain of 0.5. The styrenic resin composition according to claim 1 or 2, wherein the value divided by the elongational viscosity (MPa·s) of is 16 or more. The styrenic resin composition according to claim 1 or 2, further comprising a high melt tension and viscosity reducing component that has the effect of improving the melt tension by 5% or more and/or reducing the elongational viscosity by 5% or more. thing. The unsaturated carboxylic acid monomer unit (a2) is selected from the group consisting of (meth)acrylic acid monomer unit (a2-1) and (meth)acrylic acid ester monomer unit (a2-2). The styrenic resin composition according to claim 1 or 2, wherein the styrenic resin composition is one or more types. The styrene-unsaturated carboxylic acid resin (A) includes the styrene monomer unit (a1), the (meth)acrylic acid monomer unit (a2-1), and the (meth)acrylic acid ester monomer. Body unit (a2-2) is an essential component,
Containing 2 to 30% by mass of the (meth)acrylic acid monomer unit (a2-1) based on the entire styrene-unsaturated carboxylic acid resin (A), and the (meth)acrylic acid ester monomer The styrenic resin composition according to claim 4, containing 1 to 20% by mass of the unit (a2-2). According to claim 4, the content of all (meth)acrylic acid ester monomer units contained in the styrenic resin composition is 10 to 50% by mass with respect to the total amount of the styrenic resin composition. styrenic resin composition. The (meth)acrylic resin (B) is a copolymer consisting of a methyl methacrylate monomer unit and one or more monomer units other than methyl methacrylate; The styrenic resin composition according to claim 1 or 2, containing 10 to 98% by mass of methyl methacrylate monomer units based on the total amount. The resin composition according to claim 1 or 2, wherein the (meth)acrylic resin (B) has four or more inflection points in a differential molecular weight distribution curve. When the styrenic resin composition is divided into a first molecular weight component of 10,000 or less and a second molecular weight component of more than 10,000, the first molecular weight component of 10,000 or less is included in the total amount of the styrenic resin composition. The styrenic resin composition according to claim 1 or 2, wherein the amount is 0.5 to 3.0% by mass. The styrenic resin composition according to claim 1 or 2, further containing inorganic particles (H) in an amount of 0.05 to 3.0% by mass based on the total amount of the styrenic resin composition. A foamed extruded sheet formed by molding the styrenic resin composition according to claim 11, having a closed cell ratio of 80% or more and an average thickness in the range of 0.5 to 3 mm. A foam container formed by secondary molding the foam extrusion sheet according to claim 12.