JP7274261B2 - Styrene-based resin composition, sheet, and molded article - Google Patents

Description

The present invention relates to a styrenic resin composition, a sheet, and a molded article having excellent heat resistance, appearance, mechanical strength and transparency.

Styrene-unsaturated carboxylic acid resins are excellent in heat resistance, transparency, moldability, and rigidity, and are relatively inexpensive. It is widely used in foam boards for commercial use, diffusion plates for liquid crystal televisions containing diffusion agents, etc. In particular, for lids of packaging containers that are heated in a microwave oven or the like, there is a demand for materials that have high heat resistance and mechanical strength, and that are excellent in appearance and transparency so that the contents can be seen from the outside. In such a lid material application, in addition to the impact resistance, bending strength is required so that cracks and cracks do not occur when the product is punched in the container molding of the sheet, and the sheet itself does not break when the product is wound. High demands are made.

On the other hand, styrene-unsaturated carboxylic acid-based resins have the disadvantage of being more brittle than general polystyrene, and sheets using styrene-unsaturated carboxylic acid-based resins tend to crack during molding. There is Although a method of adding a rubber-modified styrene resin for the purpose of improving mechanical strength such as brittleness is known, it is accompanied by the drawback that heat resistance and transparency, which are the characteristics of styrene-methacrylic acid resin, tend to decrease. It is a thing. Therefore, Patent Document 1 proposes a resin composition and a sheet to which high impact polystyrene (HIPS) is added as a rubber-modified styrenic resin. In addition, Patent Document 2 proposes a technique related to a biaxially oriented sheet using a styrene-unsaturated carboxylic acid-based resin, for which transparency is particularly required, and Patent Document 3 proposes a technique of further adding silicone oil to improve strength. It is

JP 2012-207201 A JP 2015-21074 A Japanese Patent Application Laid-Open No. 2017-105954

However, the invention described in Patent Document 1 is insufficient in terms of transparency and heat resistance because the amount of the rubber component is relatively high. is low, the heat resistance and transparency are satisfactory, but the strength is insufficient. The method of Patent Document 3 has the drawback that the addition of silicone oil lowers transparency and heat resistance.
Under such circumstances, the problem to be solved by the present invention is to provide a styrenic resin composition, a sheet, and a molded article that are excellent in heat resistance, appearance, mechanical strength, and transparency.

The present inventors have made intensive research to solve the above-mentioned problems, and as a result of repeated experiments, have identified a styrene-unsaturated carboxylic acid-based resin with a specific composition and dispersed particles containing a rubber-like elastic body with a specific composition. The inventors have found that a styrene-based resin composition excellent in heat resistance, appearance, mechanical strength and transparency can be obtained by blending them in a ratio, and have completed the present invention. That is, the present invention is as follows.

[1]
When the total content of styrene-based monomer units, unsaturated carboxylic acid-based monomer units, and unsaturated carboxylic acid ester-based monomer units is 100% by mass, the content of the styrene-based monomer units is 54 to 96 mass%, the content of the unsaturated carboxylic acid monomer unit is 4 to 16 mass%, and the content of the unsaturated carboxylic acid ester monomer unit is 0 to 30 mass %; and when the total content of the aromatic hydrocarbon monomer unit and the conjugated diene monomer unit is 100% by mass, the aromatic hydrocarbon monomer Rubber-like elasticity comprising an aromatic hydrocarbon-conjugated diene copolymer having a monomer unit content of 20 to 50% by mass and a conjugated diene monomer unit content of 50 to 80% by mass. body and
When the total content of styrene-based monomer units and (meth)acrylic acid ester-based monomer units is 100% by mass, the styrene-based A copolymer (b) having a monomer content of 85 to 100% by mass and a (meth)acrylic acid ester-based monomer unit content of 0 to 15% by mass, and particles Dispersed particles (B) having a diameter of 0.5 to 3.5 μm
including
When the total content of the styrene copolymer resin (A) and the dispersed particles (B) is 100% by mass, the content of the dispersed particles (B) is 0.1 to 3.0% by mass. A styrene-based resin composition characterized by:
[2]
When the total content of the styrene-based monomer unit and the (meth)acrylic acid ester-based monomer unit is 100% by mass, the content of the styrene-based monomer unit is 85 to 100% by mass, and the Further containing a styrene resin (C) having a (meth)acrylic acid ester monomer unit content of 0 to 15% by mass,
When the total content of the styrene copolymer resin (A), the dispersed particles (B), and the styrene resin (C) is 100% by mass, the styrene copolymer resin (A) is 90.0% by mass. ~99.9% by mass, the dispersed particles (B) are 0.1 to 3.0% by mass, and the styrene resin (C) is 0.0 to 12.0% by mass, according to [1] A styrenic resin composition.
[3]
When the weight average molecular weight of the styrene copolymer resin (A) is Mw_A and the weight average molecular weight of the styrene resin (C) is Mw_C, the ratio of the molecular weight of Mw_C to Mw_A (Mw_C/Mw_A) is 0.5 to 1.5, the styrene resin composition according to [2].
[4]
The styrene resin composition according to any one of [1] to [3], wherein the dispersed particles (B) have a refractive index of 1.555 to 1.575.
[5]
The styrene-based resin composition according to any one of [1] to [4], wherein 90% or more of the dispersed particles (B) have a salami shape when observed with a transmission electron microscope.
[6]
A sheet comprising the styrenic resin composition according to any one of [1] to [5].
[7]
A biaxially oriented sheet [8] comprising the styrenic resin composition according to any one of [1] to [5]
A molded product comprising the sheet according to [6] or [7].

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a styrene-based resin composition, a sheet, and a molded article that are excellent in heat resistance, appearance, mechanical strength, and transparency.

A specific example of the cross-sectional shape of the dispersed particles (B) of the present embodiment is shown. (a) is salami-like, (b) is core-shell-like, and (c) is onion-like. A black part indicates a rubber-like elastic body, and a white part indicates an occlude polymer. In addition, the graft polymer is not shown in the figure.

Hereinafter, embodiments of the present invention will be described in detail.
[Styrene resin composition]
As described above, the styrene-based resin composition of the present embodiment is
When the total content of styrene-based monomer units, unsaturated carboxylic acid-based monomer units, and unsaturated carboxylic acid ester-based monomer units is 100% by mass, the content of the styrene-based monomer units is 54 to 96 mass%, the content of the unsaturated carboxylic acid monomer unit is 4 to 16 mass%, and the content of the unsaturated carboxylic acid ester monomer unit is 0 to 30 mass %; and when the total content of the aromatic hydrocarbon monomer unit and the conjugated diene monomer unit is 100% by mass, the aromatic hydrocarbon monomer Rubber-like elasticity comprising an aromatic hydrocarbon-conjugated diene copolymer having a monomer unit content of 20 to 50% by mass and a conjugated diene monomer unit content of 50 to 80% by mass. body and
When the total content of styrene-based monomer units and (meth)acrylic acid ester-based monomer units is 100% by mass, the styrene-based A copolymer (b) having a monomer content of 85 to 100% by mass and a (meth)acrylic acid ester-based monomer unit content of 0 to 15% by mass, and particles Dispersed particles (B) having a diameter of 0.5 to 3.5 μm
including
When the total content of the styrene copolymer resin (A) and the dispersed particles (B) is 100% by mass, the content of the dispersed particles (B) is 0.1 to 3.0% by mass. It is characterized by

<Styrene-based copolymer resin (A)>
The styrene-based copolymer resin (A) contained in the styrene-based resin composition of the present embodiment includes styrene-based monomer units, unsaturated carboxylic acid-based monomer units, and unsaturated carboxylic acid ester-based monomer units. It is a copolymer containing

Styrenic monomers include, for example, styrene, α-methylstyrene, α-methyl-p-methylstyrene, ο-methylstyrene, m-methylstyrene, p-methylstyrene, vinyltoluene, ethylstyrene, isobutylstyrene, Styrene derivatives such as t-butylstyrene, bromostyrene, chlorostyrene and indene can be mentioned. Styrene is preferred from an industrial point of view. These styrenic monomers can be used singly or in combination of two or more.

In the present embodiment, the total content of styrene-based monomer units, unsaturated carboxylic acid-based monomer units, and unsaturated carboxylic acid ester-based monomer units in the copolymer resin (A) is 100% by mass. , the content of the styrenic monomer is 54 to 96% by mass, preferably 74 to 92% by mass, and more preferably 77 to 85% by mass. If this content is less than 54% by mass, the fluidity of the resin is reduced. Since it cannot exist, the desired effect cannot be obtained.

Examples of unsaturated carboxylic acid monomers include methacrylic acid, acrylic acid, maleic anhydride, maleic acid, fumaric acid, and itaconic acid. These can be used singly or in combination. Methacrylic acid is preferred because it has a large effect of improving heat resistance and is liquid at room temperature and has excellent handling properties.

In the present embodiment, the unsaturated carboxylic acid-based monomer unit contributes to improving heat resistance. When the total content of styrene-based monomer units, unsaturated carboxylic acid-based monomer units, and unsaturated carboxylic acid ester-based monomer units in the copolymer resin (A) is 100% by mass, The content of unsaturated carboxylic acid-based monomer units is in the range of 4 to 16% by mass, preferably 6 to 14% by mass, more preferably 9 to 13% by mass. If the content is less than 4% by mass, the effect of improving the heat resistance is insufficient. Moreover, it is not preferable because it causes deterioration of fluidity and mechanical properties of the copolymer resin (A).

Examples of unsaturated carboxylic acid ester-based monomers include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, and cyclohexyl (meth)acrylate. mentioned. These can be used singly or in combination. As the (meth)acrylic acid ester-based monomer, methyl (meth)acrylate is preferable because it has little effect on deterioration of heat resistance.

In the production of the copolymer resin (A) of the present embodiment, the unsaturated carboxylic acid ester-based monomer undergoes dehydration of the unsaturated carboxylic acid-based monomer through intermolecular interaction with the unsaturated carboxylic acid-based monomer. It is used to suppress the reaction and to improve the mechanical strength of the copolymer resin (A). Furthermore, the addition of the unsaturated carboxylic acid ester monomer contributes to the improvement of resin properties such as weather resistance and surface hardness.

When the total content of styrene-based monomer units, unsaturated carboxylic acid-based monomer units, and unsaturated carboxylic acid ester-based monomer units in the copolymer resin (A) is 100% by mass, the unsaturated The content of the saturated carboxylic acid ester monomer is 0 to 30% by mass, preferably 3 to 25% by mass, more preferably 6 to 20% by mass, from the viewpoint of sheet appearance and strength. If the content exceeds 30% by mass, the fluidity of the copolymer resin (A) tends to decrease and the water absorption tends to increase, which is not preferable.

The styrene copolymer resin (A) contains a desired monomer unit other than the styrene monomer unit, the unsaturated carboxylic acid monomer unit, and the unsaturated carboxylic acid ester monomer unit. Although it can be further contained within a range that does not impair the effect, it typically consists of a styrene-based monomer unit, an unsaturated carboxylic acid-based monomer unit, and an unsaturated carboxylic acid ester-based monomer unit. The content of other monomer units may be 0 to 10% by mass with respect to 100% by mass of the styrene copolymer resin (A).

The content of the styrene-based monomer unit, the unsaturated carboxylic acid-based monomer unit, and the unsaturated carboxylic acid ester-based monomer unit in the styrene-based copolymer resin (A) is It can be obtained from the integral ratio of the spectrum when measured with a nuclear magnetic resonance ( ¹³ C-NMR) measuring device.

In the present embodiment, the total amount of styrene-based monomer units, unsaturated carboxylic acid-based monomer units, and unsaturated carboxylic acid ester-based monomer units in the copolymer resin (A) is The total residual amount of the styrene-based monomer, the unsaturated carboxylic acid-based monomer, and the unsaturated carboxylic acid ester-based monomer is preferably 1500 mass ppm or less, more preferably 1000 mass ppm or less, and still more preferably It is 500 mass ppm or less. If the total amount of the styrene-based monomer, the unsaturated carboxylic acid-based monomer, and the unsaturated carboxylic acid ester-based monomer is 1500 ppm by mass or less, the odor around the die exit during sheet extrusion and the copolymerization The color tone of resin (A) is improved. Here, the residual amounts of the styrene-based monomer, the unsaturated carboxylic acid-based monomer, and the unsaturated carboxylic acid ester-based monomer can each be measured by gas chromatography.

In the present embodiment, when the mass of the copolymer resin (A) is 100% by mass, a styrene-based monomer, an unsaturated carboxylic acid-based monomer, an unsaturated carboxylic acid ester-based monomer, and a solvent The total amount of volatile components (% by mass) is the total remaining amount of the
It is more preferably 600 mass ppm or less.
The total amount of volatile components in the styrenic copolymer resin (A) can be measured by the procedure described in the section [Examples] below or an equivalent procedure.

In the present embodiment, the melt mass flow rate (MFR) of the copolymer resin (A) is
It is preferably 0.3 to 4.0 g/10 minutes, more preferably 0.5 to 2.0 g/10 minutes, still more preferably 0.7 to 1.7 g/10 minutes. By setting the melt mass flow rate in the range of 0.3 to 4.0 g/10 minutes, a styrene resin composition having excellent moldability during sheet film formation can be obtained.
The melt mass flow rate is a value measured at 200° C. and a load of 49 N in accordance with ISO 1133.

In the present embodiment, the Vicat softening temperature of the copolymer resin (A) is preferably 110° C. or higher, more preferably 119° C. or higher, and still more preferably 122° C. or higher, from the viewpoint of the usage environment in a microwave oven. be. Moreover, there is no particular upper limit for the Vicat softening temperature.
The Vicat softening temperature can be measured according to ISO306.

In the present embodiment, the number average molecular weight (Mn) of the copolymer resin (A) is preferably 40,000 to 200,000, more preferably 50,000 to 150,000, still more preferably 70,000 to 120,000. be.
In the present embodiment, the weight average molecular weight (Mw) of the copolymer resin (A) is preferably 100,000 to 350,000, and the ratio of the Z average molecular weight (Mz) to the weight average molecular weight (Mw) (Mz/ Mw) is preferably from 1.6 to 3.5.
Mw is more preferably 130,000 to 300,000, still more preferably 160,000 to 250,000. When the Mw is 100,000 to 350,000, a resin having an excellent balance between impact strength and fluidity can be obtained, and gelled matter tends to be less mixed.
The Mz/Mw ratio is more preferably 1.7 to 3.0, more preferably 1.7 to 2.5. When the ratio of Mz/Mw is 1.6 to 3.5, a resin having an excellent balance between impact strength and fluidity can be obtained, and contamination with gelled substances tends to be small.
Mn, Mz, and Mw of the styrene copolymer resin (A) can be measured by gel permeation chromatography in terms of polystyrene standards.

The styrene-based copolymer resin (A) of the present embodiment described above may be a single resin, or a mixed resin in which two or more types are combined.
In the case of a mixed resin, the physical properties of the styrene-based copolymer resin (A) may be determined for the mixed resin. A mixed resin can be obtained by kneading two or more resins.

In the styrene resin composition of the present embodiment, when the total content of the styrene copolymer resin (A) and the dispersed particles (B) is 100% by mass, the content of the styrene copolymer resin (A) is , preferably 97.0 to 99.9% by mass, more preferably 98.0 to 99.8% by mass, even more preferably 99.0 to 99.7% by mass.
Further, when the styrene resin composition further contains a styrene resin (C) described later, the total content of the styrene copolymer resin (A), the dispersed particles (B) and the styrene resin (C) is 100 The content of the styrene-based copolymer resin (A) is preferably 90.0 to 99.9% by mass, more preferably 90.0 to 98.5% by mass, when expressed as % by mass. , more preferably 95.0 to 97.0% by mass.

The method for polymerizing the copolymer resin (A) is not particularly limited, but a bulk polymerization method or a solution polymerization method can be employed as the radical polymerization method. The polymerization method mainly comprises a polymerization step of polymerizing raw materials for polymerization (monomer components) and a devolatilization step of removing volatile matter such as unreacted monomers and polymerization solvent from the polymerization product.

In the copolymer resin (A), it is possible to obtain a resin excellent in appearance and transparency by controlling the composition distribution of the unsaturated carboxylic acid-based monomer. As for the adjustment of the composition distribution, there are a method of carrying out during polymerization, a method of blending the polymer after devolatilization, and adjusting to a predetermined composition distribution, and the like.

Hereinafter, the method for polymerizing the copolymer resin (A) of the present embodiment will be described in more detail.

When the raw materials for polymerization are polymerized to obtain the copolymer resin (A), the raw material composition for polymerization typically contains a polymerization initiator and a chain transfer agent. Examples of polymerization initiators include organic peroxides such as 2,2-bis(t-butylperoxy)butane, 1,1-bis(t-butylperoxy)cyclohexane, n-butyl-4,4-bis(t- butylperoxy)valerate, dialkylperoxides such as di-t-butylperoxide, t-butylcumylperoxide and dicumylperoxide, diacylperoxides such as acetylperoxide and isobutyrylperoxide, diisopropylperoxydicarbonate and peroxydicarbonates 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.

A chain transfer agent may be used as necessary during the polymerization of the copolymer resin (A). Chain transfer agents include, for example, α-methylstyrene linear dimer, n-dodecylmercaptan, t-dodecylmercaptan, n-octylmercaptan and the like.

For example, dimers and trimers of styrene are produced during the polymerization of styrene, unsaturated carboxylic acid, and methyl (meth)acrylate, which are raw materials of the copolymer resin (A). The amount of styrene dimers and trimers produced varies depending on the polymerization initiation method. That is, the amount of these compounds produced differs between the case of using an organic peroxide or an azo polymerization initiator as the polymerization initiator and the case of only thermal initiation. The amount of styrene dimers and trimers produced is lowest with organic peroxides and highest with thermal initiation alone. Dimers and trimers of styrene may cause problems such as the adhesion of mucus to the exit of the die during extrusion in an extruder and the adhesion of mucus to the mold during injection molding. Therefore, it is preferable to use an organic peroxide as a polymerization initiator as a polymerization initiation method.
The total amount of styrene dimers and trimers in 100% by mass of the copolymer resin (A) is preferably as low as possible, more preferably 0.7% by mass or less, and even more preferably 0.6% by mass or less. be. Styrene dimers and trimers include 1,3-diphenylpropane, 2,4-diphenyl-1-butene, 1,2-diphenylcyclobutane, 1-phenyltetralin, 2,4,6-triphenyl-1 -hexene, 1-phenyl-4-(1′-phenylethyl)tetralin and the like.
The residual amounts of styrene dimers and trimers can be measured by gas chromatography.

As a polymerization method, solution polymerization using a polymerization solvent can be adopted as necessary. Examples of the polymerization solvent to be used include aromatic hydrocarbons such as ethylbenzene, dialkylketones such as methyl ethyl ketone, and each of them may be used alone or in combination of two or more. Other polymerization solvents such as aliphatic hydrocarbons can be further mixed with the aromatic hydrocarbons as long as they do not reduce the solubility of the polymerization product. These polymerization solvents are preferably used in an amount not exceeding 30 parts by mass with respect to 100 parts by mass of the total monomers. If the polymerization solvent is 30 parts by mass or less with respect to 100 parts by mass of all the monomers, it is preferable because the decrease in the polymerization rate and the mechanical strength of the obtained resin are suppressed. Addition of 5 to 30 parts by mass per 100 parts by mass of all monomers prior to polymerization facilitates homogenization of quality and is also preferable from the viewpoint of polymerization temperature control.

By adding a gelling inhibitor to the styrene copolymer resin (A) of the present embodiment, it is possible to suppress the formation of a gel and improve the appearance of the sheet. Examples of gelation inhibitors include aliphatic monoalcohols and polyoxyethylene monoethers, and the method of addition is not particularly limited. A method of kneading in with an extruder. As for the amount to be added, it is desirable to add 0.05 to 0.3 parts by mass to the resin.

Various additives commonly used in styrene resins may be appropriately added to the styrene copolymer resin (A) of the present embodiment. Examples thereof include stabilizers, antioxidants, ultraviolet absorbers, lubricants, release agents, plasticizers, antiblocking agents, antistatic agents, antifogging agents, and mineral oils. A reinforcing material such as a styrene-butadiene block copolymer or MBS resin may also be added within a range that does not impair the physical properties. The content of these various additives is preferably 10% by mass or less with respect to 100% by mass of the styrene copolymer resin (A).
There are no particular restrictions on the method of blending additives, but for example, when adding and polymerizing during polymerization of a copolymer or when obtaining a resin composition, additives are mixed in advance in a blender, extruder or Banbury mixer. and the like.

The apparatus used in the polymerization step for obtaining the copolymer resin (A) is not particularly limited, and may be appropriately selected according to the polymerization method to be used. For example, in the case of bulk polymerization, a polymerization apparatus in which one or a plurality of complete mixing reactors are connected can be used.
In addition, the devolatilization step is not particularly limited, and in the case of bulk polymerization, the polymerization is continued until the unreacted monomer is preferably 50% by mass or less, more preferably 40% by mass or less. In order to remove volatile matter such as monomers, devolatilization treatment is performed by a known method. For example, ordinary devolatilizers such as flash drums, twin-screw devolatilizers, thin film evaporators and extruders can be used, but devolatilizers with a small stagnant portion are preferred. The temperature of the devolatilization treatment is usually about 190 to 280 ° C., and from the viewpoint of suppressing the formation of a six-membered cyclic acid anhydride due to the adjacency of (meth) acrylic acid and methyl (meth) acrylate, the temperature is 190 ° C. ~260°C is more preferred. The pressure of the devolatilization treatment is usually about 0.13 to 4.0 kPa, preferably 0.13 to 3.0 kPa, more preferably 0.13 to 2.0 kPa. As the devolatilization method, for example, a method of reducing the pressure under heating to remove the volatile matter, or a method of removing the volatile matter through an extruder or the like designed for the purpose of removing the volatile matter is desirable.

<Dispersed particles (B)>
Dispersed particles (B) contained in the styrene-based resin composition of the present embodiment, when the total content of the aromatic hydrocarbon-based monomer unit and the conjugated diene-based monomer unit is 100% by mass, An aromatic hydrocarbon-conjugated diene copolymer having an aromatic hydrocarbon-based monomer unit content of 20 to 50% by mass and a conjugated diene-based monomer unit content of 50 to 80% by mass. The total content of styrene-based monomer units and (meth)acrylic acid ester-based monomer units as a rubber-like elastic body including a coalescence and a graft polymer and/or occluded polymer to the rubber-like elastic body When 100% by mass, the content of the styrene monomer is 85 to 100% by mass, and the content of the (meth)acrylic acid ester monomer unit is 0 to 15% by mass. It contains coalescence (b) and has a particle size of 0.5 to 3.5 μm.
The dispersed particles (B) are obtained by polymerizing only a styrene-based monomer or a styrene-based monomer and a (meth)acrylic acid ester-based monomer in the presence of a rubber-like elastomer.

-Rubber-like elastic body-
The rubber-like elastomer contained in the dispersed particles (B) is an aromatic hydrocarbon-based monomer when the total content of the aromatic-hydrocarbon-based monomer unit and the conjugated diene-based monomer unit is 100% by mass. The aromatic hydrocarbon-conjugated diene copolymer has a monomer unit content of 20 to 50% by mass and a conjugated diene monomer unit content of 50 to 80% by mass.

Examples of aromatic hydrocarbon monomers include styrene, α-methylstyrene, α-methyl-p-methylstyrene, ο-methylstyrene, m-methylstyrene, p-methylstyrene, vinyltoluene, ethylstyrene, Examples include styrene derivatives such as isobutylstyrene, t-butylstyrene, bromostyrene, chlorostyrene, and indene. Styrene is preferred from an industrial point of view. These may be used alone or in combination of two or more.
The content of the aromatic hydrocarbon-based monomer units in the rubber-like elastic body is, when the total content of the aromatic hydrocarbon-based monomer units and the conjugated diene-based monomer units is 100% by mass, It is 20 to 50% by mass, preferably 30 to 40% by mass, more preferably 33 to 37% by mass. When the content of the aromatic hydrocarbon-based monomer unit is 20 to 50% by mass,
A resin composition having excellent transparency can be obtained.

A conjugated diene-based monomer is a diolefin having a pair of conjugated double bonds, such as 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1 ,3-butadiene, 1,3-pentadiene, 1,3-hexadiene, isoprene and the like. In particular, 1,3-butadiene is desirable because of its excellent impact strength. These may be used alone or in combination of two or more.
The content of the conjugated diene-based monomer unit in the rubber-like elastic body is 50 to 50% when the total content of the aromatic hydrocarbon-based monomer unit and the conjugated diene-based monomer unit is 100% by mass. 80% by mass, preferably 60 to 70% by mass, more preferably 63 to 67% by mass. When the content of the conjugated diene-based monomer unit is 50 to 80% by mass, a resin composition having excellent mechanical strength can be obtained.

The structure of the aromatic hydrocarbon-conjugated diene copolymer may be either a random structure or a block structure. In the case of a 1,3-butadiene block structure, both a high-cis polybutadiene block with a high content of cis structure and a low-cis polybutadiene block with a low content of cis structure can be used for the conjugated diene block. A saturated rubber obtained by hydrogenating a conjugated diene block can also be used.

-Copolymer (b)-
Dispersed particles (B) have a styrene monomer content of 85 to 100 mass when the total amount of styrene monomer units and (meth)acrylic acid ester monomer units is 100% by mass. % and the content of (meth)acrylic acid ester monomer units is 0 to 15% by mass, and/or a graft polymer and/or Alternatively, it is included as an occluded polymer encapsulated in a rubber-like elastic body.

Examples of the styrene monomer include styrene, α-methylstyrene, α-methyl-p-methylstyrene, ο-methylstyrene, m-methylstyrene, p-methylstyrene, vinyltoluene, ethylstyrene, isobutylstyrene. , t-butylstyrene, bromostyrene, chlorostyrene and indene. Styrene is preferred from an industrial point of view. These styrenic monomers can be used singly or in combination of two or more.
The content of the styrene-based monomer unit in the copolymer (b) is 85 to 85 when the total amount of the styrene-based monomer unit and the (meth)acrylic acid ester-based monomer unit is 100% by mass. 100% by mass, preferably 90 to 100% by mass, more preferably 95 to 100% by mass. The content of styrene-based monomer units is 85 to 100% by mass.

Examples of the (meth)acrylic ester-based monomers include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, and (meth)acryl Acid cyclohexyl etc. are mentioned. These can be used singly or in combination. If the amount of the styrene-based monomer is less than 85% by mass, the transparency deteriorates when added to the styrene-based copolymer resin (A).

The content of the (meth)acrylic acid ester-based monomer units in the copolymer (b) is 100% by mass of the total amount of the styrene-based monomer units and the (meth)acrylic acid ester-based monomer units. is 0 to 15% by mass, preferably 0 to 10% by mass, and more preferably 0 to 5% by mass.

The particle size of the dispersed particles (B) in the resin composition is 0.5 to 3.5 μm, preferably 0.6 to 2.0 μm, more preferably 0.7 to 1.5 μm. When the particle size is 0.5 μm or more, a resin composition having excellent surface impact strength and folding endurance can be obtained. Moreover, when the particle diameter is 3.5 μm or less, the transparency of the resin composition is good.
The particle diameter of the dispersed particles (B) is determined by mixing a styrene-based monomer or a styrene-based monomer and a (meth)acrylic acid ester-based monomer in a reactor equipped with a stirrer in the presence of a rubber-like elastic body. Polymerization can be adjusted by the number of revolutions of the stirrer, the molecular weight of the rubber-like elastomer used, and the like.

The average particle diameter (μm) of dispersed particles (B) is a value calculated by the following formula for 200 particles observed by cross-sectional observation with a transmission electron microscope.
Average particle size = Σ(ni×Di ⁴ )/Σ(ni×Di ³ )
(In the formula, ni is the number of dispersed particles (B) having a particle diameter Di, and Di is the average value of the major and minor diameters of the particles.)

Examples of the form of the dispersed particles (B) include core-shell form, salami form, and onion form. FIG. 1 shows examples of (a) salami-like, (b) core-shell-like, and (c) onion-like cross-sectional shapes of dispersed particles (B). In FIG. 1, the black portion indicates the rubber-like elastic body, and the white portion indicates the occluded polymer. Note that the graft polymer is not shown.
In the present embodiment, the form of the dispersed particles (B) is preferably salami-like. “Salami-like” means a form having a plurality of occluded polymer portions scattered in a rubber-like elastic body, as shown in FIG. 1(a).
In the present embodiment, preferably 80% or more, more preferably 90% or more of the dispersed particles (B) are salami-like. When the particle form is salami-like, a resin composition having excellent impact strength can be obtained.
The form of the dispersed particles (B) can be confirmed by observing the cross section of the dispersed particles (B) using a transmission electron microscope. The proportion of particles having salami-like particle morphology is a value calculated by the procedure described in the section [Examples] below.

The swelling index of the dispersed particles (B) is preferably 8.0 to 14.0, and the mass of the dispersed particles (B) with respect to the mass of the conjugated diene monomer-derived component contained in the dispersed particles (B) (mass of dispersed particles (B)/mass of component derived from conjugated diene monomer contained in dispersed particles (B)) is preferably 1.5 to 4.0. This swelling index is more preferably 9.0 to 13.0, still more preferably 9.5 to 12.5. The mass ratio of (B) is more preferably 2.0 to 3.5, still more preferably 2.5 to 3.5. The swelling index of the dispersed particles (B) is 8.0 to 14.0, and the ratio of the mass of the dispersed particles (B) to the mass of the conjugated diene monomer-derived component contained in the dispersed particles (B) is If it is 1.5 to 4.0, a resin having excellent mechanical strength can be obtained.
The swelling index of the dispersed particles (B) is a value measured by the procedure described in the section [Examples] below or an equivalent procedure.
The swelling index of the dispersed particles (B) can be measured as the swelling index of the toluene-insoluble matter in the styrenic resin composition. The swelling index of the toluene-insoluble matter is a value measured by the procedure described in the section [Examples] below.
Further, "ratio of the mass of the dispersed particles (B) to the mass of the conjugated diene monomer-derived component contained in the dispersed particles (B) (the mass of the dispersed particles (B) / the conjugated diene contained in the dispersed particles (B) The mass of the monomer-derived component)” is a value obtained by calculating the “content of the dispersed particles (B) in the HIPS resin/content of the conjugated diene monomer-derived component in the HIPS resin”. .

The dispersed particles (B) preferably have a refractive index of 1.555 to 1.575. More preferably 1.560 to 1.570. If the dispersed particles (B) have a refractive index of 1.555 to 1.575, a resin composition having excellent transparency can be obtained when kneaded with the styrene copolymer resin (A).
The refractive index is measured at 23° C. in accordance with JIS K7142 using an Appe refractometer (DR-M2 manufactured by Atago Co., Ltd.).

In the styrene-based resin composition of the present embodiment, the content of the dispersed particles (B) is 0.00% when the total content of the styrene-based copolymer resin (A) and the dispersed particles (B) is 100% by mass. It is 1 to 3.0% by mass, preferably 0.2 to 2.0% by mass, more preferably 0.3 to 1.0% by mass. If the content of the dispersed particles (B) is less than 0.1% by mass, a sufficient reinforcing effect cannot be obtained.
Further, when the styrene resin composition further contains a styrene resin (C) described later, the total content of the styrene copolymer resin (A), the dispersed particles (B) and the styrene resin (C) is 100 %, the content of the dispersed particles (B) is preferably 0.1 to 3.0% by mass, more preferably 0.3 to 2.0% by mass, and 0.5% by mass. More preferably 6 to 1.0% by mass.
The content of the dispersed particles (B) is measured as the content of the toluene-insoluble matter in the styrene resin composition or the mixed resin (HIPS resin) of the dispersed particles (B) and the styrene resin (C). can be done. The content of toluene-insoluble matter is a value measured by the procedure described in the section [Examples] below.

<<Method for producing dispersed particles (B)>>
As an example of a method for producing the dispersed particles (B) of the present embodiment, a styrene-based monomer and a (meth)acrylic acid ester-based monomer in which a rubber-like elastic body is dissolved are used, and if necessary, a polymerization solvent and a polymerization A catalyst, a chain transfer agent, etc. are added and mixed, and the unit is continuously added to a facility equipped with one or more reactors arranged in series and / or parallel and a volatile matter removal process for removing unreacted monomers, etc. A so-called continuous bulk polymerization method, in which the particles are fed and the polymerization proceeds stepwise, is preferably used. Examples of the type of reactor include a complete mixing type, a laminar flow type, and a loop type reactor in which a portion of the polymerization liquid is withdrawn while the polymerization proceeds. Although there is no particular limitation on the order of arrangement of these reactors, a laminar flow reactor is preferably used. In the devolatilization step, a vacuum devolatilization tank equipped with a heater, a devolatilization extruder, or the like is generally used. For example, a vacuum devolatilizing tank with a heater is used only in one stage, a vacuum devolatilizing tank with a heater is connected in two stages in series, or a vacuum devolatilizing tank with a heater and a devolatilizing extruder are used. are connected in series, but in order to reduce the volatile content as much as possible, a vacuum devolatilization tank with a heater is connected in series in two stages, or a vacuum devolatilization tank with a heater and A series connection with a devolatilizing extruder is preferred.

<Styrene resin (C)>
The styrene resin composition containing the above-mentioned styrene copolymer resin (A) and dispersed particles (B) further contains a styrene resin (C ) may contain.

In the present embodiment, the styrene-based resin (C) is a resin containing only styrene-based monomer units or styrene-based monomer units and (meth)acrylic acid ester-based monomer units. However, the styrene resin (C) is a resin other than the styrene copolymer resin (A).

Styrenic monomers include, for example, styrene, α-methylstyrene, α-methyl-p-methylstyrene, ο-methylstyrene, m-methylstyrene, p-methylstyrene, vinyltoluene, ethylstyrene, isobutylstyrene, Styrene derivatives such as t-butylstyrene, bromostyrene, chlorostyrene and indene can be mentioned. Styrene is preferred from an industrial point of view. These styrenic monomers can be used singly or in combination of two or more.

In the present embodiment, the content of styrene-based monomer units in the styrene-based resin (C) is the total content of styrene-based monomer units and (meth)acrylic acid ester-based monomer units of 100% by mass. , the content is preferably 85 to 100% by mass, more preferably 90 to 100% by mass, and still more preferably 95 to 100% by mass. If the content of the styrenic monomer units is less than 85% by mass, the dispersibility in the composition will be poor and the transparency will be lowered.

Examples of (meth)acrylic acid ester-based monomers include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, cyclohexyl (meth)acrylate, and the like. are mentioned. These can be used singly or in combination. As the (meth)acrylic acid ester-based monomer, methyl (meth)acrylate is preferable because it has little effect on deterioration of heat resistance.

The content of the (meth)acrylic acid ester-based monomer units in the styrene resin (C) is 100% by mass of the total content of the styrene-based monomer units and the (meth)acrylic acid ester-based monomer units. , it is preferably 0 to 15% by mass, more preferably 0 to 10% by mass, and still more preferably 0 to 5% by mass.

In the present embodiment, the weight average molecular weight (Mw) of the styrene resin (C) is preferably 100,000 to 250,000, more preferably 120,000 to 200,000. By setting the weight-average molecular weight of the styrene-based resin (C) to 100,000 to 250,000, a resin having excellent fluidity can be obtained.
Further, when the Mw of the styrene copolymer resin (A) is Mw_A and the Mw of the styrene resin (C) is Mw_C, the ratio of Mw_C to the weight average molecular weight Mw_A (Mw_C/Mw_A) is 0.5 to 1.0. It is preferably 5, more preferably 0.6 to 1.2, still more preferably 0.7 to 0.9. When the molecular weight ratio is within the above range, the styrene-based resin (C) can easily be finely dispersed in the composition, resulting in good transparency.
The Mw of the styrenic resin (C) can be measured by gel permeation chromatography in terms of polystyrene standards.

As for the method of mixing the styrene resin (C) into the resin composition, the styrene copolymer resin (A) and the dispersed particles (B) may be mixed separately, or the dispersed particles (B) may be mixed separately. Sometimes, a mixture with the styrenic resin (C), a so-called HIPS resin, may be produced at the same time and then mixed with the styrenic copolymer resin (A).

In the styrene resin composition of the present embodiment, the content of the styrene resin (C) is the total content of the styrene copolymer resin (A), the dispersed particles (B), and the styrene resin (C). When 100% by mass, it is preferably 0.0 to 12.0% by mass, more preferably 1.2 to 8.0% by mass, still more preferably 2.4 to 4.0% by mass is. If the content of the styrene-based resin (C) exceeds 12.0% by mass, sufficient transparency cannot be obtained.

The properties of the styrenic resin composition are described below.

The Vicat softening temperature of the styrene-based resin composition is 108° C. or higher, preferably 116° C. or higher, more preferably 120° C. or higher, from the viewpoint of the usage environment in a microwave oven. Moreover, there is no particular upper limit for the Vicat softening temperature.
The Vicat softening temperature can be measured according to ISO306.

When the styrene-based resin composition is molded into a 2 mm-thick molded article, the haze is preferably 10% or less, more preferably 6% or less, and still more preferably 5% or less. Within this range, sufficient transparency can be maintained when molded into a non-foamed sheet.
Haze can be measured according to ISO14728. Moreover, there is no particular lower limit for the haze degree.

Various additives that are commonly used in styrene resins may be appropriately added to the styrene resin composition of the present embodiment. Examples thereof include stabilizers, antioxidants, ultraviolet absorbers, lubricants, release agents, plasticizers, antiblocking agents, antistatic agents, antifogging agents, and mineral oils. A reinforcing material such as a styrene-butadiene block copolymer or MBS resin may also be added within a range that does not impair the physical properties. The method of blending is not particularly defined, but for example, when adding and polymerizing during polymerization of a copolymer or when obtaining a resin composition, additives are mixed in advance with a blender and then extruded with an extruder or Banbury mixer. The method of melt-kneading, etc. are mentioned.
The content of the additive in the styrenic resin composition may be 10% by mass or less.

[Method for producing styrene resin composition]
The styrenic resin composition of the present embodiment is prepared by, for example, radically polymerizing the above-described styrene-based monomer, the unsaturated carboxylic acid-based monomer, and the unsaturated carboxylic acid ester-based monomer by the above-described production method. Obtained styrene copolymer resin (A), the above-mentioned dispersed particles (B), if necessary styrene resin (C), additives, etc. It can be obtained by a method of melt-kneading using a kneader.

[Sheet]
Another embodiment of the present embodiment is a sheet manufactured using the styrene-based resin composition described above. The sheet may be non-foamed or foamed. A commonly known method can be used as a method for manufacturing the sheet. As a method for producing a non-foamed sheet, a method using an apparatus for extruding with a single-screw or twin-screw extruder equipped with a T-die, and then taking up the sheet with a uniaxial or biaxial stretching machine can be used. As a method for producing the foamed sheet, a method using an extrusion foam molding machine equipped with a T-die or a circular die, or the like can be used.

For non-foamed sheets, for example, the thickness is preferably about 0.1 to 1.0 mm from the viewpoint of rigidity and thermoforming cycle. In addition, the sheet may be formed only by normal roll stretching at a low magnification, but in particular, after stretching about 1.3 to 7 times with a roll, the sheet stretched about 1.3 to 7 times with a tenter has a high strength. preferred in terms of Also, it may be used in a multi-layered manner with a styrene-based resin such as polystyrene resin. Further, it may be used in a multi-layered manner with a resin other than a styrene-based resin. Examples of resins other than styrene-based resins include PET resins and nylon resins.

The foam sheet preferably has a thickness of 0.5 mm to 5.0 mm, an apparent density of 50 g/L to 300 g/L, and a basis weight of 80 g/m2 to 300 g/m2. The foam sheet may be multi-layered, for example, by further laminating a film. The types of films used are general polystyrene, polypropylene, polypropylene/polystyrene laminated films, and the like.

When producing a foamed sheet, as a foaming agent and a foaming nucleating agent at the time of extrusion foaming, substances commonly used can be used. As the blowing agent, butane, pentane, Freon, carbon dioxide, water, etc. can be used, and butane is preferred. Moreover, talc etc. can be used as a foaming nucleating agent. Further, after foaming and extrusion, the sheet may be stretched with a roll by about 1.3 to 7 times while being heated, and then stretched by a tenter by about 1.3 to 7 times.

[Molding]
Another embodiment is a non-foamed or foamed sheet molding as described above. A foam sheet or a multi-layer body containing the same can be formed, for example, by vacuum forming to produce a container such as a tray. Also, the non-foamed sheet can be formed, for example, by vacuum forming to produce a lid material for a boxed lunch or a container for storing side dishes.

The present invention will be specifically described below with reference to Examples and Comparative Examples, but it should not be construed that the present invention is limited to these Examples. The analysis and evaluation methods for the resins, sheets, etc. in Examples and Comparative Examples are as follows.

[Analysis/evaluation method]
(1) Measurement of Vicat softening temperature The Vicat softening temperature (°C) of the styrene copolymer resin (A) and the styrene resin composition was measured according to ISO306. The load was 49N, and the heating rate was 50°C/h.

(2) Measurement of weight average molecular weight, number average molecular weight, and Z average molecular weight Weight average molecular weights (Mw_A and Mw_C) of styrene copolymer resin (A) and styrene resin (C), styrene copolymer resin (A) The number average molecular weight (Mn), Z average molecular weight (Mz), and molecular weight distribution (Mz/Mw) of were measured using gel permeation chromatography (GPC) under the following conditions.
Sample preparation: Dissolve resin in tetrahydrofuran to a concentration of about 0.05% by mass Measurement conditions Instrument: TOSOH HLC-8220GPC
(Gel permeation chromatography)
Column: super HZM-H
Temperature: 40°C
Carrier: THF 0.35 mL/min
Detector: RI, UV: 254 nm
Calibration curve: TOSOH standard PS use

(3) Measurement of content of styrene-based monomer units, unsaturated carboxylic acid-based monomer units, and unsaturated carboxylic acid ester-based monomer units Amount of styrene-based monomer in styrene-based copolymer resin (A) Body unit, unsaturated carboxylic acid-based monomer unit, content (mass%) of unsaturated carboxylic acid ester-based monomer unit, and styrene-based monomer unit in HIPS resin, (meth) acrylic acid ester The monomer unit content (% by mass) was determined by quantifying the resin composition from the integral ratio of the spectrum measured with a nuclear magnetic resonance ( ¹³ C-NMR) device. Sample preparation: 75 mg of resin was dissolved in 0.75 mL of d6-DMSO by heating at 60° C. for 4 to 6 hours.
Measuring instrument: JNM ECA-500 manufactured by JEOL Ltd.
Measurement conditions: measurement temperature 60°C, observation core ^13C , accumulation times 20,000 times, repetition time 45 seconds

(4) Measurement of total volatile content Styrene-based monomer, (meth)acrylic acid-based monomer, (meth)acrylic acid ester when the mass of styrene-based copolymer resin (A) is 100% by mass The total amount of the system monomer and the residual amount of the solvent was measured by gas chromatography as the total amount of volatile components (% by mass).
-Sample preparation: After dissolving 2.0 g of resin in 20 mL of chloroform, 5 mL of methanol containing a standard substance (triphenylmethane) was added to reprecipitate the polymer component, and the supernatant was collected as a measurement solution.
・Measurement conditions Equipment: Agilent 6850 series GC system Detector: FID
Column: HP-1 (100% dimethylpolysiloxane) 30 m, film thickness 0.25 μm, 0.32 mmφ
Injection volume: 1 μL (splitless)
Column temperature: Hold at 40°C for 2 minutes → Heat up to 320°C at 20°C/min → Hold at 320°C for 15 minutes Inlet temperature: 250°C
Detector temperature: 280°C
Carrier gas: Helium

(5) Measurement of styrene dimers and trimers The residual amount (% by mass) of styrene dimers and trimers in the styrene copolymer resin (A) was measured under the following conditions and procedures. It was measured.
-Sample preparation: After dissolving 2.0 g of resin in 20 mL of chloroform, 5 mL of methanol containing a standard substance (triphenylmethane) was added to reprecipitate the polymer component, and the supernatant was collected as a measurement solution.
・Measurement conditions Equipment: Agilent 6850 series GC system Detector: FID
Column: HP-1 (100% dimethylpolysiloxane) 30 m, film thickness 0.25 μm, 0.32 mmφ
Injection volume: 1 μL (splitless)
Column temperature: Hold at 40°C for 2 minutes → Heat up to 320°C at 20°C/min → Hold at 320°C for 15 minutes Inlet temperature: 250°C
Detector temperature: 280°C
Carrier gas: helium

(6) Transparency Based on ISO14728, haze (HAZE) was measured using a 2 mm-thick plate injection-molded in a mirror-finished flat mold.

(7) Production of Stretched Sheet A sheet having a thickness of 1.15 to 1.35 mm was produced from the styrene-based resin composition using a 25 mmφ single-screw sheet extruder (manufactured by Soken Co., Ltd.). A sheet having a size of 10 cm×10 cm was cut out from the prepared sheet. The cut sheet was subjected to simultaneous biaxial stretching under the following conditions using a biaxial stretching apparatus (manufactured by Toyo Seiki Co., Ltd., EX6-S1) to prepare a stretched sheet having a thickness of 0.25 (±0.1) mm.
Stretching temperature: Vicat softening temperature +20°C,
Stretching speed: 170%
Stretch ratio: 2.5 times

(8) Measurement of impact strength (kgf cm) of stretched sheet Produced by the method described in (7) above using a film impact tester (manufactured by Toyo Seiki Co., Ltd., model No. 195 (serial number A-12180752)). The impact strength (Kgf·cm) of the stretched sheet was measured under conditions of 23° C. and 50% RH.

(9) Measurement of MIT Folding Endurance (Times) of Stretched Sheet Based on JIS P8115, the MIT folding endurance (times) of the sheet produced by the method described in (7) above was measured.

(10) Measurement of Melt Flow Rate (MFR) Melt flow rate (MFR) (g/10 min) of styrene copolymer resin (A) and HIPS resin was measured according to ISO 1133 (200°C, load 49N ).

(11) Content of Dispersed Particles (B) and Measurement of Swelling Index The insoluble content (% by mass) and swelling index were measured as follows.
Accurately weigh 1 g of the resin composition or HIPS resin in a sedimentation tube (this mass is defined as W1), add 20 ml of toluene, shake at 23° C. for 2 hours, and centrifuge (himac, manufactured by Hitachi, Ltd.). CR-20 (rotor: R20A2)) was centrifuged at 20000 rpm at 10° C. or less for 60 minutes. The sedimentation tube was slowly tilted to about 45 degrees and the supernatant liquid was decanted and removed. Accurately weigh the mass of the toluene-containing insoluble matter (this mass is W2), then vacuum dry for 1 hour under conditions of 160 ° C. and 3 kPa or less, cool to room temperature in a desiccator, and then weigh the toluene insoluble matter. was accurately weighed (this mass is defined as W3).
The swelling index and content of the toluene-insoluble matter were determined by the following formula.
Toluene-insoluble content (% by mass) = ((W3)/(W1)) x 100
Swelling index of toluene insolubles = (W2/W3)

(12) Measurement of content of conjugated diene monomer-derived component in HIPS resin The content (% by mass) of the conjugated diene monomer-derived component in the HIPS resin was measured as follows. Accurately weigh 4 g of HIPS resin in a volumetric flask (this mass is W), add 75 mL of chloroform and disperse well, add 20 mL of a solution of 18 g of iodine monochloride dissolved in 1000 mL of carbon tetrachloride, and store in a cool dark place. It was stored and after 8 hours chloroform was added and adjusted to the mark. 25 mL of this was collected, 60 mL of a solution of 10 g of potassium iodide dissolved in 800 mL of water and 200 mL of ethanol was added, and 10 g of sodium thiosulfate was dissolved in 1000 mL of water. was titrated with A mL of the main test and B mL of the blank test were used, and the content (% by mass) of the component derived from the conjugated diene monomer was determined by the following formula.
Content of component derived from conjugated diene monomer = 10.8 × xx (BA) / W

(13) Measurement of particle size of dispersed particles (B) The average particle size (μm) of the dispersed particles (B) in the HIPS resin is obtained by taking a transmission electron microscope photograph by the ultrathin section method, and measuring 200 particles in the photograph. The particle size was measured and obtained by the following formula.
Average particle size = Σ(ni×Di ⁴ )/Σ(ni×Di ³ )
(In the formula, ni is the number of dispersed particles (B) having a particle diameter Di. Di is the average value of the major and minor diameters of the particles.)

(14) Measurement of refractive index of dispersed particles (B) The refractive index of the dispersed particles (B) in the HIPS resin was obtained by separating the dispersed particles (B) and the styrene resin (C) in the same manner as in (11) above. After drying the toluene solvent, measurement was performed at 23° C. in accordance with JIS K7142 using an Abbe refractometer (manufactured by Atago Co., Ltd., DR-M2).

(15) Calculation of Percentage of Particles Having Salami Shape in Dispersed Particles (B) A photograph was taken, 200 particles in the photograph were observed, and the percentage of salami-shaped particles was calculated.

[material]
-Raw materials for styrene copolymer resin (A)-
Styrene-based monomer: Styrene [manufactured by Asahi Kasei]
Unsaturated carboxylic acid-based monomer: methacrylic acid [manufactured by Mitsubishi Gas Chemical Company]
Unsaturated carboxylic acid ester-based monomer: methyl methacrylate [manufactured by Asahi Kasei Corporation]
Polymerization initiator: 1,1-bis (t-butylperoxy) cyclohexane (manufactured by NOF CORPORATION)
Solvent: Ethylbenzene [manufactured by Asahi Kasei Corporation]

-HIPS Raw Material Containing Dispersed Particles (B) and Styrenic Resin (C)-
Styrene-based monomer: Styrene [manufactured by Asahi Kasei]
(Meth) acrylic acid ester-based monomer: methyl methacrylate [manufactured by Asahi Kasei Corporation]
Rubber-like elastic body: Styrene-butadiene copolymer 1 (SB1) [manufactured by Asahi Kasei Corporation, trade name: Asaprene 625A]
Rubber-like elastic body: Styrene-butadiene copolymer 2 (SB2) [manufactured by Asahi Kasei Corporation, trade name: Asaprene 670A]
Rubber-like elastic body: polybutadiene rubber 1 (PB1) [manufactured by Asahi Kasei Corporation, trade name: diene 35]
Rubber-like elastic body: polybutadiene rubber 2 (PB2) [manufactured by Ube Industries, trade name: BR15HB]
Polymerization initiator: 1,1-bis (t-butylperoxy) cyclohexane [manufactured by NOF Corporation]
Chain transfer agent: n-dodecyl mercaptan [manufactured by NOF Corporation]
Chain transfer agent: α-methylstyrene dimer [manufactured by NOF Corporation]
Solvent: Ethylbenzene [manufactured by Asahi Kasei Corporation]

[Preparation of styrene copolymer resin (A)]
[Resin A-1]
Polymerization of 70 parts by mass of styrene, 8.5 parts by mass of methacrylic acid, 6.5 parts by mass of methyl methacrylate, 15.0 parts by mass of ethylbenzene, and 0.025 parts by mass of 1,1-bis(t-butylperoxy)cyclohexane The raw material composition liquid is degassed at a rate of 0.8 L / hour by connecting a complete mixing reactor with a capacity of 3.6 L and a single screw extruder for removing volatile matter such as unreacted monomers and polymerization solvents. It was continuously supplied to the volatilization apparatus sequentially. The polymerization temperature in the fully mixed reactor was 124°C. The temperature of the single-screw extruder was set to 200-250° C., and unreacted monomers were devolatilized under a reduced pressure of 10 torr. The devolatilized unreacted gas was condensed in a condenser through which a -5° C. refrigerant was passed, and recovered as an unreacted liquid, and the polymer portion was recovered as resin pellets.
The polymer content in the polymerization liquid after the reaction was measured by (mass of sample after drying/mass of sample before drying×100%) after drying the polymerization liquid for 30 minutes at 215° C. under reduced pressure of 3 kPa. It was 7% by mass.
Table 1 shows the physical properties obtained by the above analytical method.

[Resin A-2]
Resin A was prepared under the same production conditions as Resin A except that the polymerization raw material composition liquid was styrene 71.3 parts by mass, methacrylic acid 5.7 parts by mass, ethylbenzene 19.0 parts by mass, and cyclohexane 0.023 parts by mass. -2 was produced.
Table 1 shows the physical properties obtained by the above analytical method.

[Resin A-3]
48.8 parts by mass of styrene, 8.2 parts by mass of methacrylic acid, 17.0 parts by mass of methyl methacrylate, 26.0 parts by mass of ethylbenzene, and 0 of 1,1-bis(t-butylperoxy)cyclohexane. Resin A-3 was produced under the same production conditions as Resin A, except that the amount was 0.025 parts by mass and the reactor temperature was 130°C.
Table 1 shows the physical properties obtained by the above analytical method.

[Production of HIPS containing dispersed particles (B) containing rubber-like elastomer and styrene resin (C)]
[Resin D]
79.2 parts by mass of styrene as a styrene-based monomer, 7.9 parts by mass of methyl methacrylate as a (meth)acrylic ester-based monomer, and 10.8 parts of styrene-butadiene copolymer 1 as a rubber-like elastic body parts by mass, 10 parts by mass of ethylbenzene as a solvent, 0.02 parts by mass of 1,1-bis(t-butylperoxy)cyclohexane as a polymerization initiator, and 0.03 parts by mass of n-dodecylmercaptan as a chain transfer agent. The resulting polymerization liquid was continuously charged at 3.2 L/hour into a 6.2 L laminar flow reactor-1 equipped with a stirrer and capable of temperature control, and the temperature was adjusted to 130 to 145°C. The number of revolutions of the stirrer was 150 revolutions per minute.
Subsequently, the reaction solution was sent to a 6.2 L laminar flow reactor-2 equipped with a stirrer and capable of temperature control, which was connected in series with the laminar flow reactor-1. Further, a liquid of 90 parts by mass of styrene, 10 parts by mass of ethylbenzene and 1 part by mass of n-dodecylmercaptan was added to the reactor-2 at 0.08 L/hour. The number of revolutions of the stirrer was set at 20 revolutions per minute, and the temperature was set at 120-140°C.
Subsequently, the reaction solution was sent to a 6.2 L laminar flow reactor-3 equipped with a stirrer and capable of temperature control. The number of revolutions of the stirrer was set at 10 revolutions per minute, and the temperature was set at 130-150°C. A polymer solution continuously discharged from a polymerization reactor (laminar flow reactor-3) was devolatilized and then pelletized by an extruder equipped with a vacuum vent under a reduced pressure of 10 torr. The temperature of the extruder was set at 200-250°C.
Table 2 shows the physical properties of Resin D obtained by the above analytical method.

[Resin E]
The composition of the mixed and dissolved polymerization liquid is 79.0 parts by mass of styrene, 10.8 parts by mass of rubber-like elastic material, 10 parts by mass of ethylbenzene, 0.02 parts by mass of 1,1-bis(t-butylperoxy)cyclohexane, and Resin E was produced under the same conditions as Resin D, except that 0.03 parts by mass of n-dodecylmercaptan was used as a chain transfer agent and the rotation speed of the laminar flow reactor-1 was changed to 50 rpm.
Table 2 shows the physical properties of Resin E obtained by the above analytical method.

[Resin F]
Polybutadiene rubber 1 was used as the rubber-like elastic material, and the composition of the mixed and dissolved polymerization liquid was 79 parts by weight of styrene, 7 parts by weight of the rubber-like elastic material, 15 parts by weight of ethylbenzene, and 1,1-bis(t-butylperoxy). 0.06 parts by mass of cyclohexane and 0.05 parts by mass of α-methylstyrene dimer were continuously charged at 3.2 L / hour into a temperature-controllable 6.2 L laminar flow reactor-1, and the temperature was adjusted. It was adjusted to 110-130°C. The number of revolutions of the stirrer was 40 revolutions per minute.
Subsequently, the reaction solution was sent to a 6.2 L laminar flow reactor-2 equipped with a stirrer and capable of temperature control, which was connected in series with the laminar flow reactor-1. The number of revolutions of the stirrer was set at 15 revolutions per minute, and the temperature was set at 130-150°C.
Subsequently, the reaction solution was sent to a 6.2 L laminar flow reactor-3 equipped with a stirrer and capable of temperature control. The number of revolutions of the stirrer was set at 10 revolutions per minute, and the temperature was set at 140-170°C. A polymer solution continuously discharged from a polymerization reactor (laminar flow reactor-3) was devolatilized and then pelletized by an extruder equipped with a vacuum vent under a reduced pressure of 10 torr. The temperature of the extruder was set at 200-250°C.
Table 2 shows the physical properties of Resin F obtained by the above analytical method.

[Resin G]
Styrene-butadiene copolymer 2 was used as the rubber-like elastic material, and the composition of the mixed and dissolved polymerization liquid was 76 parts by weight of styrene, 9 parts by weight of the rubber-like elastic material, 15 parts by weight of ethylbenzene, 1,1-bis(t -Butylperoxy)cyclohexane 0.04 parts by mass, n-dodecyl mercaptan 0.03 parts by mass, and the rotation speed of the laminar flow reactor-1 was 200 rpm. Resin G was prepared at
Table 2 shows the physical properties of Resin G obtained by the above analytical method.

[Resin H]
86.6 parts by mass of styrene as a styrene-based monomer, 8.4 parts by mass of styrene-butadiene copolymer 1 as a rubber-like elastic body, 5.0 parts by mass of ethylbenzene as a solvent, and 1,1-bis as a polymerization initiator. A polymerization liquid prepared by mixing and dissolving 0.02 parts by mass of (t-butylperoxy)cyclohexane was continuously charged at 3.2 L/hour in a 6.2 L laminar flow reactor-1 equipped with a stirrer and capable of temperature control. After charging, the temperature was adjusted to 100-120°C. The number of revolutions of the stirrer was 200 revolutions per minute.
Subsequently, the reaction liquid is sent to a 6.2 L laminar flow reactor-2 equipped with a stirrer and capable of temperature control, which is connected in series with the laminar flow reactor-1, and the stirrer rotates at 20 revolutions per minute. and the temperature was set to 120-130°C.
Subsequently, the reaction solution was sent to a 6.2 L laminar flow reactor-3 equipped with a stirrer and capable of temperature control. The number of revolutions of the stirrer was set at 10 revolutions per minute, and the temperature was set at 130-140°C. A polymer solution continuously discharged from a polymerization reactor (laminar flow reactor-3) was devolatilized and then pelletized by an extruder equipped with a vacuum vent under a reduced pressure of 10 torr. The temperature of the extruder was set at 200-250°C.
Table 2 shows the physical properties of Resin H obtained by the above analytical method.

[Resin I]
Polybutadiene rubber 2 was used as the rubber-like elastic material, 77 parts by weight of styrene, 9 parts by weight of the rubber-like elastic material, 14 parts by weight of ethylbenzene as the solvent, and 0.1 parts by weight of 1,1-bis(t-butylperoxy)cyclohexane as the polymerization initiator. 004 parts by mass, 0.2 parts by mass of α-methylstyrene dimer as a chain transfer agent, and the rotation speed of the laminar flow reactor-1 was 35 rpm. I was manufactured.
Table 2 shows the physical properties of Resin I obtained by the above analytical method.

[Resin J]
Styrene-butadiene copolymer 1 is used as the rubber-like elastic material, and 40 parts by weight of styrene, 38 parts by weight of methyl methacrylate, 9 parts by weight of the rubber-like elastic material, 13 parts by weight of ethylbenzene, 1,1-bis(t-butyl Peroxy)cyclohexane 0.02 parts by mass, α-methylstyrene dimer 0.1 parts by mass, and the rotation speed of the laminar flow reactor-1 was 120 rpm, the same conditions as for resin F Resin J was produced at
Table 2 shows the physical properties of Resin J obtained by the above analytical method.

[Example 1]
98.5 parts of the obtained styrene-based copolymer resin (A) [Resin A-1] and 1.5 parts of HIPS [Resin D] were added, and extruded using a 30 mm diameter twin-screw extruder (manufactured by Soken Co., Ltd.). , 220° C. and 80 rpm, and then pelletized to obtain a styrenic resin composition.
Table 3 shows the evaluation results of the obtained styrenic resin composition.

[Examples 2 to 5, 7]
Add the styrene copolymer resin (A) and the HIPS resin in the proportions shown in Table 3, and knead at 220° C. and 80 rpm using a 30 mmφ twin-screw extruder in the same manner as in Example 1. A resin composition was obtained.
Table 3 shows the evaluation results of the obtained styrenic resin composition.

[ Reference Example 6]
Resin E was dissolved in toluene to a concentration of 10% by mass, the solution was placed in a centrifuge tube, and centrifuged (manufactured by Hitachi Ltd., himac, CR-20 (rotor: R20A2)) at 10°C or less and 20,000 rpm. and centrifuged for 60 minutes. The supernatant liquid in which the styrene resin (C) is dissolved is removed by decantation, and the dispersed particles (B) derived from the resin E remaining in the centrifuge tube as a precipitate are collected, and the conditions are 80° C., 1.3 kPa, and 1 hour. Solvent was removed. 99.5 parts by mass of the styrene copolymer resin (A) and 0.5 parts by mass of dispersed particles (B) derived from resin E from which the solvent was removed were added, and in the same manner as in Example 1, a 30 mm diameter biaxial extrusion was performed. After kneading at 220° C. and 80 rpm using a machine, the mixture was pelletized to obtain a styrenic resin composition.
Table 3 shows the evaluation results of the obtained styrenic resin composition.

[Comparative Example 1]
A styrenic resin composition was obtained in the same manner as in Example 1 except that the dispersed particles (B) and the styrenic resin (C) were not added.
Table 3 shows the evaluation results of the obtained styrene resin.
In Comparative Example 1, in which the dispersed particles (B) and the styrene resin (C) were not present, the strength of the resin composition was remarkably lowered as compared with Example 1, and the impact strength and MIT folding endurance were also lowered.

[Comparative Example 2]
A styrenic resin composition was obtained in the same manner as in Example 2, except that the amount of Resin E added was changed to 13.0 parts by mass.
Table 3 shows the evaluation results of the obtained styrene resin.
Compared to Example 2, the added amount of the dispersed particles (B) was large, resulting in insufficient transparency.

[Comparative Example 3]
Kneading was carried out in the same manner as in Example 1 except that 99.0 parts by mass of the styrene copolymer resin (A) [resin A-1] and 1.0 part of HIPS [resin F] were used to obtain a styrene resin composition. got stuff
Table 3 shows the evaluation results of the obtained styrenic resin composition.
The rubber-like elastic body contained in the dispersed particles (B) of the resin F does not have a predetermined composition, and the transparency of the composition is poor. Although the amount to be added was set, sufficient mechanical strength (impact strength, MIT folding endurance) could not be obtained.

[Comparative Example 4]
Kneading was carried out in the same manner as in Example 1 except that the styrene copolymer resin (A) [resin A-1] was 98.0 parts by mass and HIPS [resin F] was 2.0 parts, and a styrene resin composition was obtained. got stuff
Table 3 shows the evaluation results of the obtained styrenic resin composition.
In Comparative Example 4, the amount of [Resin F] was increased compared to Comparative Example 3, so that the mechanical strength was improved, but sufficient transparency was not obtained.

[Comparative Example 5]
Kneading was carried out in the same manner as in Example 1 except that the styrene copolymer resin (A) [resin A-1] was 98.0 parts by mass and HIPS [resin G] was 2.0 parts, and a styrene resin composition was obtained. got stuff
Table 3 shows the evaluation results of the obtained styrenic resin composition.
Dispersed particles (B) derived from [Resin G] had a small particle diameter and did not have a salami-like shape as a main component, and thus had a low impact strength.

[Comparative Example 6]
Kneading was carried out in the same manner as in Example 1 except that 98.0 parts by mass of the styrene copolymer resin (A) [resin A-1] and 2.0 parts of HIPS [resin I] were used to obtain a styrene resin composition. got stuff
Table 3 shows the evaluation results of the obtained styrenic resin composition.
Since the dispersed particles (B) derived from [Resin I] had a large particle size, the resulting composition had poor transparency.

[Comparative Example 7]
Kneading was carried out in the same manner as in Example 1 except that the styrene copolymer resin (A) [Resin A-1] was 98.0 parts by mass and HIPS [Resin J] was 2.0 parts, and a styrene resin composition was obtained. got stuff
Table 3 shows the evaluation results of the obtained styrenic resin composition.
In the graft polymer and occluded polymer resin and the styrenic resin (C) contained in the dispersed particles (B) derived from [Resin J], the amount of methyl methacrylate is greater than a predetermined amount, so the dispersibility is poor, and the composition The result was that the transparency was inferior when

Since the styrene resin composition of the present invention is excellent in heat resistance, mechanical strength, appearance and transparency, it can be used in non-foamed and foamed extruded plates, sheets, and molded products obtained by secondary processing thereof, such as injection molding. etc. (for example, containers and packaging materials for foods such as box lunches and side dishes).

Claims (8)

When the total content of styrene-based monomer units, unsaturated carboxylic acid-based monomer units, and unsaturated carboxylic acid ester-based monomer units is 100% by mass, the content of the styrene-based monomer units is 54 to 96 mass%, the content of the unsaturated carboxylic acid monomer unit is 4 to 16 mass%, and the content of the unsaturated carboxylic acid ester monomer unit is 0 to 30 mass % styrene copolymer resin (A);
When the total content of the aromatic hydrocarbon-based monomer unit and the conjugated diene-based monomer unit is 100% by mass, the content of the aromatic hydrocarbon-based monomer unit is 20 to 50% by mass. a rubber-like elastomer containing an aromatic hydrocarbon-conjugated diene-based copolymer in which the content of the conjugated diene-based monomer units is 50 to 80% by mass; and a graft polymer of the rubber-like elastomer and/or Or as an occlude polymer, when the total content of styrene-based monomer units and (meth) acrylic acid ester-based monomer units is 100% by mass, the content of the styrene-based monomer is 85 to 100 % by mass and the content of the (meth)acrylic acid ester-based monomer units is 0 to 15% by mass, and the copolymer (b) has a particle diameter of 0.5 to 3.5 μm. Dispersed particles (B) which are; 85 to 100% by mass, containing a styrene resin (C) having a content of the (meth)acrylic acid ester-based monomer unit of 0 to 15% by mass,
When the total content of the styrene copolymer resin (A), the dispersed particles (B) , and the styrene resin (C) is 100% by mass, the content of the dispersed particles (B) is 0.1. ~ 3.0% by mass, the content of the styrene resin (C) is more than 0.0 and 12.0% by mass or less,
When the weight average molecular weight of the styrene copolymer resin (A) is Mw_A and the weight average molecular weight of the styrene resin (C) is Mw_C, the ratio of the molecular weight of Mw_C to Mw_A (Mw_C/Mw_A) is 0.5 to 1.5, a styrenic resin composition. When the total content of the styrene copolymer resin (A), the dispersed particles (B), and the styrene resin (C) is 100% by mass, the styrene copolymer resin (A) is 90.0% by mass. 9 to 8.5 % by mass, the dispersed particles (B) are 0.1 to 3.0% by mass, and the styrene resin (C) is 1.1 to 8.0% by mass, according to claim 1 styrenic resin composition. The styrene-based copolymer resin (A) has a total content of the styrene-based monomer unit, the unsaturated carboxylic acid-based monomer unit, and the unsaturated carboxylic acid ester-based monomer unit of 100% by mass. 3. The styrenic resin composition according to claim 1, wherein the content of the unsaturated carboxylic acid ester monomer unit is 0 to 10% by mass. The styrene resin composition according to any one of claims 1 to 3, wherein the dispersed particles (B) have a refractive index of 1.555 to 1.575. The styrenic resin composition according to any one of claims 1 to 4, wherein 90% or more of the dispersed particles (B) are salami-shaped when the cross-sectional shape of the dispersed particles (B) is observed using a transmission electron microscope. A sheet comprising the styrenic resin composition according to any one of claims 1 to 5. A biaxially oriented sheet comprising the styrenic resin composition according to any one of claims 1 to 5 A molded article characterized by comprising the sheet according to claim 6 or 7.

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