JP6829103B2 - Styrene-based resin, sheet, molded product and manufacturing method - Google Patents

Description

The present invention relates to a styrene resin, a sheet, a molded product, and a manufacturing method having excellent strength, heat resistance, appearance, and transparency.

Styrene-unsaturated carboxylic acid-based resin has excellent heat resistance and rigidity, and is relatively inexpensive. Therefore, it can be used as a container and packaging material for foods such as lunch boxes and prepared foods, foam boards for heat insulating materials for houses, and diffusers. It is widely used as a diffuser for a liquid crystal television in which it is placed, but it is particularly used as a lid material for a packaging container to be heated in a range or the like.

However, the styrene-unsaturated carboxylic acid resin has a drawback that cross-linking is likely to occur due to dehydration condensation between unsaturated carboxylic acids, and poor appearance is likely to occur when the non-foamed or foamed sheet is formed. Further, the styrene-unsaturated carboxylic acid-based resin has a drawback that the composition distribution tends to occur during polymerization and the transparency tends to be impaired.

Japanese Unexamined Patent Publication No. 2011-126996 Japanese Unexamined Patent Publication No. 3-243605

However, although the method of copolymerizing methyl methacrylate in Patent Document 1 improves the appearance, the improving effect is insufficient. Further, although Patent Document 2 has a description regarding the composition distribution, it is only a description regarding the improvement of transparency, and a description regarding the appearance cannot be found.
Therefore, the present invention provides a styrene-based resin, a sheet, a molded product, and a method for producing a resin, which are excellent in strength, heat resistance, appearance, and transparency.

As a result of diligent research and repeated experiments to solve the above problems, the present inventors have given a specific composition distribution to a styrene-unsaturated carboxylic acid-based- (meth) acrylic acid ester resin having a specific composition. As a result, it was found that a styrene-based resin having excellent strength, heat resistance, appearance and transparency, as well as a sheet and a molded product can be obtained.
That is, the present invention is as follows.

[1] When the total content of the styrene-based monomer unit, the unsaturated carboxylic acid-based monomer unit, and the (meth) acrylic acid ester-based monomer unit is 100% by mass, the styrene-based monomer is used. The content of the unit is 54% by mass or more and 96% by mass or less, the content of the unsaturated carboxylic acid monomer unit is 4% by mass or more and 16% by mass or less, and the (meth) acrylic acid ester-based single amount. A resin having a body unit content of 0% by mass or more and 30% by mass or less.
Let (a) be the average concentration of the unsaturated carboxylic acid-based monomer unit having a molecular weight fraction of 0% to 15% from the low molecular weight of the resin, and the unsaturated carboxylic acid having a molecular weight fraction of 15% to 85%. When the average concentration of the system monomer unit is (b) and the average concentration of the unsaturated carboxylic acid monomer unit of the molecular weight fraction of 85% to 100% is (c), it is 0.9%. A styrene-based resin, characterized in that ≦ (a) − (c) ≦ 3% and (c) ≦ (b) <(a).
[2] A non-foamed sheet containing the styrene resin according to [1].
[3] A foamed sheet containing the styrene resin according to [1].
[4] The sheet according to [2] or [3], which is biaxially stretched.
[5] A molded product, which is obtained by molding the sheet according to any one of [2] to [4].
[6] An injection-molded article containing the styrene-based resin according to [1].
[7] The method for producing a styrene-based resin according to [1], which is produced by continuous polymerization.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a styrene-based resin, a sheet, a molded product, and a method for producing a resin, which are excellent in strength, heat resistance, appearance, and transparency.

Hereinafter, embodiments of the present invention will be described in detail.

[Styrene resin]
In the present embodiment, when the total content of the styrene-based monomer unit, the unsaturated carboxylic acid-based monomer unit, and the methacrylic acid ester-based monomer unit in the copolymer resin is 100% by mass. The content of the styrene-based monomer is 54 to 96% by mass. It is preferably 61 to 93% by mass, and more preferably 60 to 68% by mass. If this content is less than 54% by mass, the fluidity of the resin is lowered, while if it exceeds 96% by mass, a desired amount of unsaturated carboxylic acid-based monomer unit cannot be present, which is an object of the present application. Heat resistance cannot be obtained.

Examples of the styrene-based monomer include styrene, α-methylstyrene, p-methylstyrene and the like. Although these can be used alone or in combination, styrene is preferable because it can be used industrially at low cost.

In the present embodiment, the unsaturated carboxylic acid-based monomer unit contributes to the improvement of heat resistance. Examples of the unsaturated carboxylic acid-based monomer include methacrylic acid, acrylic acid, maleic anhydride, maleic acid, fumaric acid, and itaconic acid. Methacrylic acid is preferable because it has a large effect of improving heat resistance, is liquid at room temperature, and has excellent handleability.

When the total content of the styrene-based monomer unit, the unsaturated carboxylic acid-based monomer unit, and the methacrylic acid ester-based monomer unit in the copolymer resin is 100% by mass, the unsaturated carboxylic acid-based The content of the monomer unit is 4 to 16% by mass. It is preferably in the range of 6 to 14% by mass, more preferably 8 to 12% by mass. If this content is less than 4% by mass, the effect of improving heat resistance is insufficiently exhibited, while if it exceeds 16% by mass, gelled substances in the copolymerized resin increase, resulting in poor appearance. Further, it is not preferable because it causes a decrease in fluidity and mechanical properties of the copolymerized resin.

In the present embodiment, when considering the unsaturated carboxylic acid concentration with respect to the molecular weight distribution of the resin, the average concentration of the unsaturated carboxylic acid monomer having a molecular weight fraction of 0% to 15% from the low molecular weight of the resin is (a). Let (b) be the average concentration of unsaturated carboxylic acid monomers having a molecular weight fraction of 15% to 85%, and let the average concentration of unsaturated carboxylic acid monomers having a molecular weight fraction of 85% to 100% be (b). c) Then
The composition distribution of the unsaturated carboxylic acid monomer is 0.9% ≤ (a)-(c) ≤ 3% and (c) ≤ (b) <(a), preferably 1.4%. ≤ (a)-(c) ≤ 2.2%, and (c) ≤ (b) <(a), more preferably 1.6% ≤ (a)-(c) ≤ 2.0%. And (c) ≤ (b) <(a). If the composition distribution is within this range, the resin has an excellent appearance and excellent transparency. When (a)-(c) of the composition distribution is less than 0.9%, the appearance is inferior, and when it is more than 3%, the transparency is deteriorated.
The composition distribution can be obtained from GPC-FTIR.

In the production of the copolymerized resin of the present embodiment, the (meth) acrylic acid ester-based monomer dehydrates the unsaturated carboxylic acid-based monomer by molecular interaction with the (meth) acrylic acid-based monomer. In addition to suppressing the reaction and improving the mechanical strength, it contributes to the improvement of heat-resistant oil resistance. The addition of the (meth) acrylic acid ester-based monomer also contributes to the improvement of resin properties such as weather resistance and surface hardness. Examples of the (meth) acrylic acid ester-based monomer include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, cyclohexyl (meth) acrylate, and the like. Can be mentioned. Although these can be used alone or in combination, methyl (meth) acrylate is preferable because it has a small effect on the decrease in heat resistance.

When the total content of the styrene-based monomer unit, the unsaturated carboxylic acid-based monomer unit, and the (meth) acrylic acid ester-based monomer unit in the copolymer resin is 100% by mass, (meth) The content of the acrylic acid ester-based monomer is 0% by mass or more and 30% by mass or less. It is preferably in the range of 3% by mass or more and 25% by mass or less, and even more preferably 5% by mass or more and 20% by mass or less. If it exceeds 30% by mass, the fluidity of the copolymerized resin tends to decrease and the water absorption tends to increase, which is not preferable.

The styrene-based resin contains monomer units other than the styrene-based monomer unit, the unsaturated carboxylic acid-based monomer unit, and the (meth) acrylic acid ester-based monomer unit as long as the desired effect is not impaired. Furthermore it can be contained, typically, a styrene-based monomer unit, consisting of an unsaturated carboxylic acid monomer units and (meth) acrylate Le ester monomer units. The contents of the styrene-based monomer unit, the (meth) acrylic acid-based monomer unit, and the (meth) acrylic acid ester-based monomer unit in the styrene-based resin are the nuclear magnetic resonances of the copolymerized resin, respectively. ( ¹³ C-NMR) It can be obtained from the integration ratio of the spectrum when measured by the measuring device.

In the present embodiment, the degree of fogging when molded into a 2 mm molded product of a styrene resin is preferably 5% or less, more preferably 2%. Within this range, it is possible to provide practically sufficient transparency for injection molded products, non-foamed sheet molded products, and the like.
The degree of cloudiness conforms to ISO14728 and can be measured. In addition, there is no particular lower limit on the degree of cloudiness.

In the present embodiment, the styrene-based monomer unit, the unsaturated carboxylic acid-based monomer unit, and the (meth) acrylic acid ester-based monomer unit in the copolymer resin are added to the total amount of the styrene-based monomer unit. The total residual amount of the monomer, the (meth) acrylic acid-based monomer, and the (meth) acrylic acid ester-based monomer is preferably 1000 mass ppm or less, more preferably 700 mass ppm or less, still more preferably. It is 500 mass ppm or less. If the total amount of the styrene-based monomer, the (meth) acrylic acid-based monomer, and the (meth) acrylic acid ester-based monomer is 1000 mass ppm or less, the odor around the die outlet during sheet extrusion and the above-mentioned The color tone of the copolymer resin is improved.
Here, the residual amounts of the styrene-based monomer, the (meth) acrylic acid-based monomer, and the (meth) acrylic acid ester-based monomer can be measured by gas chromatography, respectively.

In the present embodiment, the bicut softening temperature of the styrene resin is preferably 110 ° C. or higher, more preferably 118 ° C. or higher, still more preferably 122 ° C. or higher, from the viewpoint of the usage environment in a microwave oven. In addition, there is no particular upper limit to 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 styrene resin is preferably 40,000 to 200,000, the weight average molecular weight (Mw) is preferably 80,000 to 300,000, and the Z average molecular weight (Z average molecular weight). Mz) is preferably 100,000 to 1,000,000. The ratio (Mz / Mw) of the Z average molecular weight (Mz) to the weight average molecular weight (Mw) is preferably 1.6 to 3.5. Mw is preferably 100,000 to 250,000, more preferably 120,000 to 200,000. When Mw is 80,000 to 300,000, the balance between impact strength and fluidity is excellent, and gelled matter tends to be less mixed. The ratio of Mz / Mw is 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 gelled products tend to be less mixed.
Mz and Mw can be measured in polystyrene standard conversion by gel permeation chromatography.

The styrene-based resin of the present embodiment described above may be a single type of resin or a mixed resin of two or more types.
In the case of a mixed resin, the physical characteristics of the styrene-based resin may be determined for the mixed resin. The mixed resin can be obtained by kneading two or more kinds of resins.

Examples of the method for polymerizing the resin include continuous polymerization, suspension polymerization and emulsion polymerization of a massive polymerization method or a solution polymerization method as a radical polymerization method. In suspension polymerization and emulsion polymerization, continuous polymerization is particularly desirable because the appearance is impaired by suspension agents and emulsifiers. The polymerization method mainly comprises a polymerization step of polymerizing a polymerization raw material (monomer component) and a devolatilization step of removing volatile components such as unreacted monomer and polymerization solvent from the polymerization product.

In this styrene-based resin, it is possible to obtain a resin having excellent appearance and transparency by controlling the composition distribution of unsaturated carboxylic acid-based monomers. Examples of the adjustment of the composition distribution include a method performed at the time of polymerization and a method of blending the devolatile polymer to adjust the composition distribution to a predetermined value.

Examples of the apparatus used in the polymerization step for obtaining the resin include a completely mixed reactor, a column reactor, and a batch reactor, and these can be used in series or in parallel. Further, as an example of the method of controlling the composition distribution during continuous polymerization, there is a method of flowing reaction solutions having different compositions into a plurality of reactors installed in parallel in continuous polymerization and merging them. The amount of the reaction solution to be passed through the reactors installed in parallel is preferably 10% to 90% with respect to the total amount of the reaction solution. Another method is to add the reaction solution between the reactors installed in series. The amount of the reaction solution to be added is preferably 10% to 50% with respect to the reaction solution before addition, and more preferably 15% to 30% from the viewpoint of kneading property. From an industrial point of view, the final polymerization rate is preferably 50% or more, preferably 60% or more. There is no particular upper limit on the polymerization rate.

The volatilization step is also not particularly limited, and the polymerization is finally proceeded until the final polymerization reaction rate is preferably 40% by mass or more, more preferably 50% by mass or more, and the volatile components such as unreacted monomers are removed. In order to do so, the volatilization process is carried out by a known method. For example, a normal volatilizer such as a flash drum, a twin-screw volatilizer, a thin film evaporator, or an extruder can be used, but a volatilizer having a small retention portion is preferable. The temperature of the devolatilization treatment is usually about 190 ° C. to 280 ° C., and from the viewpoint of suppressing the formation of a six-membered cyclic anhydride due to the adjacency of (meth) acrylic acid and methyl (meth) acrylate. More preferably, 190 ° C to 260 ° C. The pressure of the devolatilization treatment is usually about 0.13 kPa to 4.0 kPa, preferably 0.13 kPa to 3.0 kPa, and more preferably 0.13 kPa to 2.0 kPa. As the volatilization method, for example, a method of removing volatile matter by reducing the pressure under heating, or a method of removing volatile matter through an extruder designed for the purpose of removing volatile matter is desirable.

When the polymerization raw material is polymerized to obtain the resin, a polymerization initiator and a chain transfer agent are typically contained in the polymerization raw material composition. Examples of the polymerization initiator include organic peroxides such as 2,2-bis (t-butylperoxy) butane, 1,1-bis (t-butylperoxy) cyclohexane, and n-butyl-4,4-bis (t-). Butylperoxy) Peroxyketals such as valerate, di-t-butyl peroxide, t-butylcumyl peroxide, dialkyl peroxides such as dicumyl peroxide, diacyl peroxides such as acetyl peroxide and isobutylyl peroxide, diisopropyl peroxydicarbonate. Peroxydicarbonates such as, peroxyesters such as t-butylperoxyacetate, ketone peroxides such as acetylacetone peroxide, hydroperoxides such as t-butylhydroperoxide and the like. From the viewpoint of decomposition rate and polymerization rate, 1,1-bis (t-butylperoxy) cyclohexane is particularly preferable.

A chain transfer agent can also be used when the resin is polymerized, if necessary. Examples of the chain transfer agent include α-methylstyrene linear dimer, n-dodecyl mercaptan, t-dodecyl mercaptan, n-octyl mercaptan and the like.

For example, when styrene, (meth) acrylic acid, and methyl (meth) acrylate, which are raw materials for styrene-based resins, are polymerized, styrene dimers and trimers are produced. The amount of styrene dimer or trimer produced differs depending on the method of initiation of polymerization. That is, the amounts produced differ between the case where an organic peroxide or an azo-based polymerization initiator is used as the polymerization initiator and the case where only heat initiation is used. The amount of styrene dimer or trimer produced is lowest when organic peroxide is used and highest when only heat initiation is used. Styrene dimers and trimers may cause problems due to adhesion to the eyes and eyes at the die outlet during extrusion by an extruder, adhesion to the eyes and eyes during injection molding, and the like. Therefore, as a polymerization initiation method, it is preferable to use an organic peroxide as a polymerization initiator. The lower the total amount of the dimer and trimer of styrene in 100% by mass of the styrene resin is, the more preferable, but more preferably 0.7% by mass or less, and even more preferably 0.6% by mass or less. The dimer and trimeric of styrene include 1,3-diphenylpropane, 2,4-diphenyl-1 butene, 1,2-diphenylcyclobutane, 1-phenyltetralin, and 2,4,6-triphenyl-1. -Hexene, 1-phenyl-4- (1'-phenylethyl) tetralin and the like can be mentioned.
The residual amounts of styrene dimers and trimers can be measured by gas chromatography.

In the polymerization, solution polymerization using a polymerization solvent can be adopted, if necessary. Examples of the polymerization solvent used include aromatic hydrocarbons such as ethylbenzene and dialkyl ketones such as methyl ethyl ketone, which may be used alone or in combination of two or more. Other polymerization solvents, such as aliphatic hydrocarbons, can be further mixed with aromatic hydrocarbons as long as the solubility of the polymerization product is not reduced. It is preferable to use these polymerization solvents in a range not exceeding 30 parts by mass with respect to 100 parts by mass of all the monomers. When the amount of the polymerization solvent is 30 parts by mass or less with respect to 100 parts by mass of all the monomers, a decrease in the polymerization rate and a decrease in the mechanical strength of the obtained resin are suppressed, which is preferable. Before polymerization, it is preferable to add 5 to 30 parts by mass with respect to 100 parts by mass of all the monomers because the quality can be easily made uniform and the polymerization temperature can be controlled.

In this styrene resin, by adding a gelation inhibitor, it is possible to suppress the formation of a gel product and improve the appearance when it is made into a sheet. Examples of the gelation inhibitor include aliphatic monoalcohols and polyoxyethylene monoethers, and the method of addition is not particularly limited. The gelation inhibitor is added before or during the polymerization of the resin, or is added to the produced resin pellets by an extruder. There is a method of kneading with. It is desirable to add 0.05 parts by mass to 0.3 parts by mass with respect to the resin.

Various additives generally used in the styrene resin may be appropriately added to the styrene resin of the present embodiment. Examples thereof include stabilizers, antioxidants, UV absorbers, lubricants, mold release agents, plasticizers, blocking inhibitors, antistatic agents, antifogging agents, mineral oils and the like. Further, reinforcing materials such as styrene-butadiene block copolymer and MBS resin may be added as long as the physical properties are not impaired. The method of blending is not particularly specified, but for example, when a method of adding and polymerizing a copolymer at the time of polymerization or a resin composition is obtained, the additives are mixed in advance with a blender and then used in an extruder, a Banbury mixer or the like. Examples thereof include a method of melt-kneading.

[Sheet]
Another embodiment of the present invention is a sheet produced by using the above-mentioned styrene resin and styrene resin composition. As a method for producing the sheet, a commonly known method can be used. It may be non-foamed or foamed.
For the non-foamed sheet, a method using a device that extrudes the sheet with a single-screw or twin-screw extruder equipped with a T-die and then takes out the sheet with a uniaxial stretching machine or a biaxial stretching machine can be used. As a method for producing the foam sheet, a method using an extrusion foam molding machine equipped with a T die or a circular die can be used.

In the non-foamed sheet, for example, the thickness is preferably about 0.1 mm to 1.0 mm from the viewpoint of rigidity and thermoforming cycle. Further, the sheet may be formed only by ordinary low-magnification roll stretching, or may be stretched by a roll about 1.3 to 7 times and then by a tenter about 1.3 to 7 times. Further, it may be used in multiple layers with a styrene resin such as polystyrene resin. Further, it may be used in multiple layers with a resin other than the styrene resin. Examples of the resin other than the styrene resin include PET resin, nylon resin and the like.

Foam sheet is preferably is preferably thick 0.5 mm to 5.0 mm, preferably a apparent density 50 g / to 300 g / L, also a basis weight of ^80g / ^{m 2 ~300g} / m 2 .. The foam extruded sheet of the present invention may be multi-layered, for example, by further laminating a film. The type of film used is general polystyrene, polypropylene, polypropylene / polystyrene laminated film, or the like. When forming a foamed sheet, commonly used substances can be used as the foaming agent and the foaming nucleating agent during extrusion foaming. Butane, pentane, chlorofluorocarbon, carbon dioxide, water and the like can be used as the foaming agent, and butane is preferable. Further, talc or the like can be used as the effervescent nucleating agent. Further, after foam extrusion, the sheet may be stretched about 1.3 to 7 times with a roll while heating, and then stretched about 1.3 to 7 times with a tenter.

Another embodiment is a molded product using the above-mentioned sheet. The sheet can be molded by vacuum forming, for example, to produce a container for a lunch box lid material, a side dish, or the like.

The styrene-based resin of the present invention can be used in other molding methods according to the purpose, such as injection molding and compression molding.

Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples, but the present invention should not be understood to be limited to these Examples. The methods for analyzing and evaluating resins, resin compositions, sheets, etc. in Examples and Comparative Examples are as follows.

(1) Measurement of Vicat softening temperature The measurement was performed in accordance with ISO306. The load was 49 N and the heating rate was 50 ° C./h.

(2) Measurement of weight average molecular weight, number average molecular weight, and Z average molecular weight Sample preparation: Approximately 0.05% by mass of resin dissolved in tetrahydrofuran Measuring conditions Equipment: TOSOH HLC-8220 GPC (gel permeation chromatography)
Column: super HZM-H
Temperature: 40 ° C
Carrier: THF 0.35 mL / min
Detector: RI, UV: 254 nm
Calibration curve: Uses standard PS made by TOSOH

(3) Measurement of resin composition content of styrene unit, (meth) acrylic acid unit, and (meth) acrylic acid unit Quantify the resin composition from the integral ratio of the spectrum measured by a nuclear magnetic resonance ( ¹³ C-NMR) device. did.
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 equipment: JEOL JNM ECA-500
Measurement conditions: Measurement temperature 60 ° C, observation nucleus ^13C , number of integrations 20,000 times, repetition time 45 seconds

(4) Measurement of composition distribution by GPC-FTIR Sample preparation: Dissolved in tetrahydrofuran at about 0.02% by mass of resin Measurement conditions Equipment: TOSOH HLC-8220 GPC (gel permeation chromatography)
Column: super HZM-H
Temperature: 40 ° C
Carrier: THF 1.00 mL / min
Injection volume: 100 μL
Detector: RI
FT-IR: Nicolet IS10 (manufactured by Thermo Scientific)
FT-IR interface: LC Transform 600r (manufactured by Lab Connection)
Wavenumber measured: 4000-650 cm ^-1
Resolution: 4 cm ^-1
Calibration: TOSOH made of standard PS using methacrylic acid monomers Quantification was determined from the intensity ratio A1 / A2 of the peak intensity A2 of a peak intensity A1 and 1600 cm ^-1 of 1697Cm ^-1 obtained from FT-IR.
From GPC-FTIR, the relationship between the methacrylic acid monomer (MAA) concentration of the specific molecular weight component and the differential molecular weight intensity in the differential molecular weight distribution could be obtained, and the average MAA concentration in the specific molecular weight range was calculated based on this.

(5) Vacuum heating test The resin pellets were treated in a heating furnace under the conditions of 255 ° C., 1.3 kPa and 1 h.
The analysis was carried out by the method for measuring the molecular weight of (2), and the polystyrene-equivalent molecular weight component amount (%) of 1 million or more was determined.
The rate of increase was calculated from the following formula, where A1 was the molecular weight component of 1 million or more before the test and A2 was the molecular weight of 1 million or more after the test.
Increase rate of 1 million or more components after vacuum heating test = A2 / A1

(6) Transparency In accordance with ISO14728, the degree of haze (HAZE) was measured using a 2 mm thick plate compression molded at 200 ° C. with a resin sandwiched between mirror-surfaced metal plates.

(7) Measurement of MIT Folding Strength (Times) of Stretched Sheet With the above 25 mmφ single-screw sheet extruder, 1 part of PS Japan 475D was added to 100 parts by weight of styrene resin and extruded to a thickness of 1.5 to 1. A 1.6 mm sheet was prepared. A sheet having a size of 10 cm × 10 cm was cut out from the prepared sheet. The cut out sheet was simultaneously biaxially stretched with a biaxial stretching device (EX6-S1) manufactured by Toyo Seiki under the following conditions to prepare a stretched sheet having a thickness of 0.24 to 0.26 mm.
Stretching temperature: Vicat softening temperature + 20 ° C,
Stretching speed: 170%
Magnification: 2.5 times The MIT folding resistance of the prepared sheet was measured according to JIS P8115.

(8) Appearance judgment of non-foamed sheet A sheet with a thickness of 0.3 mm was prepared by a 25 mmφ single-screw sheet extruder manufactured by Soken Co., Ltd., and 5 sheets having a size of 8 cm × 20 cm were cut out from the sheets and cut out 5 The number of gels having an average diameter of (major diameter + minor diameter) / 2 of 0.5 mm or more on the surface of one sheet was counted, and the appearance was judged by the following evaluation criteria:
◎ (Excellent): Number of gels is 3 points or less ○ (Good): Number of gels is 4 to 9 points × (Poor): Number of gels is 10 points or more

(9) Appearance Judgment of Foamed Sheet The foamed extruded sheet is made by impregnating a sheet with a thickness of about 0.2 mm produced by compression molding with liquefied carbon dioxide gas at 10 mPa for 30 minutes in an autoclave, and then heating to 125 ° C. for about 10 times. A foam sheet was prepared. Five sheets with a size of 10 cm x 10 cm are cut out from the sheets, and the number of gels having an average diameter of (major diameter + minor diameter) / 2 of 1 mm or more on the surface of the 10 sheets is counted, and the following evaluation criteria are used. Judging the appearance with:
◎ (Excellent): Number of gels is 2 points or less ○ (Good): Number of gels is 3-4 points × (Poor): Number of gels is 5 points or more

(9) Measurement of Residual Amount of Monomer The residual amount of styrene-based monomer, (meth) acrylic acid-based monomer, and (meth) acrylic acid ester-based monomer in the resin pellets is determined, respectively. It was measured by gas chromatography under the following conditions and procedures.
-Sample preparation: After 1.0 g of the resin composition was dissolved in 10 mL of acetone, 6 mL of hexane containing a standard substance (p-diethylbenzene) was further added to reprecipitate the polymer component, and the supernatant was collected and used as a measurement solution.
-Measurement conditions Equipment: Agilent 6850 series GC system Detector: FID
Column: DB-WAX (PEG) 60 m, film thickness 0.5 μm, 0.32 mmφ
Column temperature: Hold at 40 ° C for 3 minutes ⇒ Heat up to 100 ° C at 10 ° C / min ⇒ Hold at 100 ° C for 5 minutes ⇒ Heat up to 200 ° C at 10 ° C / min ⇒ Hold at 200 ° C for 20 minutes Injection volume: 1 μl ( Splitless)
Injection port temperature: 230 ° C
Detector temperature: 300 ° C
Carrier gas: helium

(10) Measurement of styrene dimer and residual amount of trimer The residual amount (mass%) of styrene dimer and trimer in the resin pellet was measured under the following conditions and procedures.
-Sample preparation: After 2.0 g of the resin composition was dissolved in 20 mL of methyl ethyl ketone, 5 mL of methanol containing a standard substance (triphenylmethane) was further added to reprecipitate the polymer component, and the supernatant was collected and used 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 → Raise to 320 ° C at 20 ° C / min → Hold at 320 ° C for 15 minutes Injection temperature: 250 ° C
Detector temperature: 280 ° C
Carrier gas: helium

[Example 1]
The polymerization raw material composition solution A composed of 80.5 parts by mass of styrene, 5.5 parts by mass of methacrylic acid, 14.0 parts by mass of ethylbenzene, and 0.026 parts by mass of 1,1-bis (t-butylperoxy) cyclohexane was added to 0. Feeding a fully mixed reactor 1 with a volume of 3.6 liters at a rate of 0.8 liters / hour, 73.5 parts by mass of styrene, 7.5 parts by mass of methacrylic acid, 19.0 parts by mass of ethylbenzene, and 1 , 1-Bis (t-butylperoxy) cyclohexane 0.026 parts by mass of a polymerization raw material composition solution B was installed in parallel with the reactor 1 at a rate of 0.8 liters / hour and had a capacity of 3.6 liters. It was supplied to a completely mixed reactor B, merged, and then continuously and sequentially supplied to a devolatilizer connected to a uniaxial extruder for removing volatile substances such as a polymerization solvent. The polymerization temperature of the complete mixing reactor 1 was 123 ° C., and the polymerization temperature of the complete mixing reactor 2 was 129 ° C.
The temperature of the uniaxial extruder was set to 200 to 250 ° C., and the unreacted monomer was devolatile under a reduced pressure of 10 torr. The devolatile unreacted gas was condensed in a condenser passed through a refrigerant at −5 ° C. and recovered as an unreacted liquid, and the polymer component was recovered as resin pellets.
The results of Example 1 are shown in Table 1.

[Example 2]
From 68.6 parts by mass of styrene, 6.3 parts by mass of methacrylic acid, 3.9 parts by mass of methyl methacrylate, 21.2 parts by mass of ethylbenzene, and 0.026 parts by mass of 1,1-bis (t-butylperoxy) cyclohexane. The polymerization raw material composition solution A is supplied to a completely mixed reactor 1 having a capacity of 3.6 liters at a rate of 0.8 liters / hour, and 61.9 parts by mass of styrene and 8.1 parts by mass of methacrylic acid. A polymerization raw material composition solution B consisting of 3.7 parts by mass of methyl methacrylate, 26.3 parts by mass of ethylbenzene, and 0.026 parts by mass of 1,1-bis (t-butylperoxy) cyclohexane was added at 0.8 liter / hour. At a rate, the solution was supplied to the complete mixing reactor B having a capacity of 3.6 liters installed in parallel with the reactor 1, the polymerization temperature of the complete mixing reactor 1 was 133 ° C., and the polymerization temperature of the complete mixing reactor 2 was 125. The temperature was adjusted to ° C. After that, it was manufactured under the same manufacturing conditions as in Example 1.
The results of Example 2 are shown in Table 1.

[Example 3]
From 70.2 parts by mass of styrene, 5.6 parts by mass of methacrylic acid, 4.4 parts by mass of methyl methacrylate, 19.8 parts by mass of ethylbenzene, and 0.026 parts by mass of 1,1-bis (t-butylperoxy) cyclohexane. The polymerization raw material composition liquid A was supplied to a completely mixed reactor 1 having a mass of 3.6 liters at a rate of 0.8 liters / hour, and polymerization was carried out at a polymerization temperature of 122 ° C. Then, volatilization was carried out under the same conditions as in Example 1 to obtain a resin 1.
Next, 60.2 parts by mass of styrene, 9.0 parts by mass of methacrylic acid, 4.0 parts by mass of methyl methacrylate, 26.8 parts by mass of ethylbenzene, and 0.026 parts of 1,1-bis (t-butylperoxy) cyclohexane. A polymerization raw material composition solution consisting of parts by mass was supplied to a 3.6 liter complete mixing reactor 2 at a rate of 0.8 liter / hour, and the reaction was carried out at a polymerization temperature of 136 ° C.
Then, volatilization was carried out under the same conditions as in Example 1 to obtain a resin 2. Resin 1 and resin 2 were extruded at a ratio of 1: 1 with a 20 mm twin-screw extruder manufactured by Soken Co., Ltd. at 220 ° C. and 50 rpm to produce the resin of Example 3.
The results of Example 3 are shown in Table 1.

[Example 4]
From 67.8 parts by mass of styrene, 6.4 parts by mass of methacrylic acid, 4.3 parts by mass of methyl methacrylate, 21.5 parts by mass of ethylbenzene, and 0.026 parts by mass of 1,1-bis (t-butylperoxy) cyclohexane. A reaction apparatus in which a completely mixed reactor 1 having a mass of 3.6 liters and a tower reactor 3 having a mass of 1.2 liters are connected in series at a rate of 0.8 liters / hour. Supplied to. A polymerization raw material composition solution consisting of 74.8 parts by mass of styrene, 19.7 parts by mass of methacrylic acid, and 5.5 parts by mass of methyl methacrylate was supplied to the outlet of the reactor 1 at a rate of 0.05 liter / hour. The polymerization temperature of the complete mixture reactor 1 was 126 ° C., and the polymerization temperature of the column reactor 3 was 135 ° C. After that, it was manufactured under the same manufacturing conditions as in Example 1.
The results of Example 4 are shown in Table 1.

[Example 5]
From 51.8 parts by mass of styrene, 9.1 parts by mass of methacrylic acid, 15.2 parts by mass of methyl methacrylate, 23.9 parts by mass of ethylbenzene, and 0.026 parts by mass of 1,1-bis (t-butylperoxy) cyclohexane. The polymerization raw material composition liquid A was supplied to a completely mixed reactor 1 having a capacity of 3.6 liters at a rate of 0.8 liters / hour, and 57.1 parts by mass of styrene and 5.5 parts by mass of methacrylic acid. A polymerization raw material composition solution B consisting of 15.6 parts by mass of methyl methacrylate, 21.8 parts by mass of ethylbenzene, and 0.026 parts by mass of 1,1-bis (t-butylperoxy) cyclohexane was added at 0.8 liter / hour. At a rate, the solution was supplied to the complete mixing reactor B having a capacity of 3.6 liters installed in parallel with the reactor 1, the polymerization temperature of the complete mixing reactor 1 was 137 ° C., and the polymerization temperature of the complete mixing reactor 2 was 124. The temperature was adjusted to ° C. After that, it was manufactured under the same manufacturing conditions as in Example 1.
The results of Example 5 are shown in Table 1.

[Comparative Example 1]
The polymerization raw material composition solution was 0.83 parts by mass of styrene, 5.7 parts by mass of methacrylic acid, 19.0 parts by mass of ethylbenzene, and 0.028 parts by mass of 1,1-bis (t-butylperoxy) cyclohexane. Polymerization was carried out by supplying to a fully mixed reactor 1 having a capacity of 3.6 liters at a rate of liters / hour. The reactor temperature was 125 ° C. After the polymerization, it was produced under the same production conditions as in Example 1.
The results of Comparative Example 1 are shown in Table 1. In Comparative Example 1, the composition distribution of methacrylic acid was small, resulting in inferior appearance.

[Comparative Example 2]
65.5 parts by mass of styrene, 6.9 parts by mass of methacrylic acid, 3.8 parts by mass of methyl methacrylate, 23.8 parts by mass of ethylbenzene, and 1,1-bis (t-butylperoxy) cyclohexane 0 in the polymerization raw material composition solution. Polymerization was carried out by supplying .026 parts by mass to a fully mixed reactor 1 having a capacity of 3.6 liters at a rate of 0.8 liters / hour. The reactor temperature was 128 ° C. After the polymerization, it was produced under the same production conditions as in Example 1.
The results of Comparative Example 2 are shown in Table 1. In Comparative Example 2, the composition distribution of methacrylic acid was small, resulting in inferior appearance.

[Comparative Example 3]
2 L of distilled water was charged into a 5 L reaction vessel, and 10 g of carboxymethyl cellulose and 0.05 g of sodium dodecylbenzene sulfonate were charged and dissolved as suspending agents, and 650 g of styrene, 150 g of methacrylic acid, 200 g of methyl methacrylate and myristyl were dissolved therein. 3 g of alcohol, 1 g of t-butylperoxybenzoate, and 2 g of α-methylstyrene dimer were sequentially charged, the inside of the machine was replaced with nitrogen, and then suspension polymerization was carried out at 80 ° C. for 7 hours with stirring, and then at 110 ° C. Polymerization was carried out for 3 hours. After dehydration, it was dried and the resin was recovered.
The results of Comparative Example 3 are shown in Table 1. In Comparative Example 3, the composition distribution of methacrylic acid was large, and the degree of cloudiness was significantly deteriorated.

The styrene-based resin composition of the present invention is a sheet having excellent heat resistance, appearance, transparency, strength, and heat-resistant oil resistance, and further, a molded product by secondary processing thereof, for example, a container and packaging material for foods such as lunch boxes and prepared foods. Can be suitably used for the production of. In addition, taking advantage of its heat-resistant oil property, it can be widely used for containers and the like formed by injection molding.

Claims (7)

When the total content of the styrene-based monomer unit, the unsaturated carboxylic acid-based monomer unit, and the (meth) acrylic acid ester-based monomer unit is 100% by mass, the content of the styrene-based monomer unit The amount is 54% by mass or more and 96% by mass or less, the content of the unsaturated carboxylic acid monomer unit is 4% by mass or more and 16% by mass or less, and the content of the (meth) acrylic acid ester-based monomer unit is A resin having a content of 0% by mass or more and 30% by mass or less.
The styrene-based monomer unit is a styrene monomer unit, the unsaturated carboxylic acid-based monomer unit is a methacrylic acid monomer unit, and the (meth) acrylic acid ester-based monomer unit is methacryl. Methyl acid monomer unit,
Let (a) be the average concentration of the unsaturated carboxylic acid-based monomer unit having a molecular weight fraction of 0% to 15% from the low molecular weight of the resin, and the unsaturated carboxylic acid having a molecular weight fraction of 15% to 85%. When the average concentration of the system monomer unit is (b) and the average concentration of the unsaturated carboxylic acid monomer unit of the molecular weight fraction of 85% to 100% is (c), it is 0.9%. A styrene-based resin, characterized in that ≦ (a) − (c) ≦ 3% and (c) ≦ (b) <(a). A non-foamed sheet containing the styrene-based resin according to claim 1. A foamed sheet containing the styrene-based resin according to claim 1. The sheet according to claim 2 or 3, wherein the sheet is biaxially stretched. A molded product, which is obtained by molding the sheet according to any one of claims 2 to 4. An injection-molded product, which comprises the styrene-based resin according to claim 1. The method for producing a styrene resin according to claim 1, wherein the styrene resin is produced by continuous polymerization.