JP7116660B2 - Styrenic resin composition, sheet and molded article - Google Patents

Description

TECHNICAL FIELD The present invention relates to a styrenic resin composition, a sheet and a molded article.

Molded articles such as beverage containers and food containers have been required to have heat resistance, rigidity, and impact resistance. A resin composition blended with a rubber-modified styrenic resin (for example, high impact polystyrene (HIPS)) is used (for example, Patent Document 1).

JP 2017-36413 A

By the way, a molded article molded from a resin composition obtained by blending the styrene-unsaturated carboxylic acid resin and the rubber-modified styrene resin (for example, high impact polystyrene (HIPS)) has heat resistance, rigidity, and heat resistance as described above. Although it has impact resistance, it is opaque, and in the molded product (for example, container) for the above purpose, it is transparent so that the contents such as beverages and foods stored or stored inside can be confirmed. Visibility is required. On the other hand, molded products are required not only to be visually recognizable, but also to have good appearance of the molded product and the contents as a whole when the contents are stored or accommodated. As a method to improve the appearance, the molded product itself becomes matte and exhibits a gradation effect, instead of making it a molded product that allows consumers and users to directly check the contents inside the molded product. There is a need for molded articles with a degree of indirectness, particularly moderately translucent molded articles, that are capable of

Accordingly, the problem to be solved by the present invention is to provide a resin composition, a sheet and a molded article having translucency, heat resistance, rigidity and impact resistance.

The inventors of the present invention have made intensive research and repeated experiments to solve the above problems. can be solved, and the present invention has been completed.
That is, the present invention is as follows.

[1] The rubber-modified styrene-based resin (A) is added to a total of 100% by mass of the rubber-modified styrene-based resin (A) containing a rubber-like elastic material as dispersed particles and the styrene-based copolymer resin (B). 50% by mass or more and less than 100% by mass, the styrene copolymer resin (B) is more than 0% by mass and 50% by mass or less, and the styrene copolymer resin (C) is added to the rubber-modified styrene resin (A) and 0 parts by mass or more and 20 parts by mass or less with respect to a total of 100 parts by mass of the styrene copolymer resin (B),
The continuous phase of the rubber-modified styrene resin (A) contains styrene monomer units when the content of styrene monomer units and unsaturated carboxylic acid ester monomer units is 100% by mass. A copolymer (a) containing 20% by mass or more and 70% by mass or less and 30% by mass or more and 80% by mass or less of unsaturated carboxylic acid ester monomer units,
The dispersed particles of the rubber-modified styrenic resin (A) have a particle diameter of 0.1 μm or more and 2.0 μm or less, and the rubber-like elastic body contains a styrene-conjugated diene copolymer and The content of the elastic body is 1% by mass or more and 20% by mass or less with respect to 100% by mass of the rubber-modified styrene resin (A),
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 styrene-based copolymer resin (B) is 100% by mass, , the styrene-based monomer unit is 54% by mass or more and 96% by mass or less, the unsaturated carboxylic acid-based monomer unit is 4% by mass or more and 16% by mass or less, and the unsaturated carboxylic acid ester-based monomer unit is Containing 0% by mass or more and 30% by mass or less,
The styrene copolymer resin (C) contains 10 mass of the styrene monomer unit when the total content of the styrene monomer unit and the unsaturated carboxylic acid ester monomer unit is 100% by mass. % or more and 90 mass % or less, and the unsaturated carboxylic acid ester monomer unit content is 10 mass % or more and 90 mass % or less.
[2] The total light transmittance measured using a 2 mm thick flat plate is 65% or more and less than 90%, and the haze measured using a 1 mm thick flat plate is 5% or more and 70% or less. The styrenic resin composition of [1].
[3] The styrenic resin composition of [1] or [2] above, wherein the Vicat softening temperature of the styrenic resin composition is 88° C. or higher.
[4] A sheet characterized by having a layer formed from the styrene resin composition of any one of [1] to [3] above.
[5] The sheet according to [4] above, further comprising a barrier layer having gas barrier properties.
[6] A molded article characterized by being formed from the sheet of [4] or [5] above.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide resin compositions, sheets and molded articles having translucency, heat resistance, rigidity and impact resistance.

Hereinafter, embodiments of the present invention will be described in detail.
[Styrene resin composition]
The styrenic resin composition of the present embodiment is a rubber-modified 50% by mass or more and less than 100% by mass of the styrene resin (A), more than 0% by mass and less than 50% by mass of the styrene copolymer resin (B), and the styrene copolymer resin (C) is rubber-modified styrene It contains 0 parts by mass or more and 20 parts by mass or less with respect to a total of 100 parts by mass of the resin (A) and the styrene copolymer resin (B). Further, the continuous phase of the rubber-modified styrenic resin (A) contains styrenic monomer units when the content of styrenic monomer units and unsaturated carboxylic acid ester monomer units is 100% by mass. 20% by mass or more and 70% by mass or less, and 30% by mass or more and 80% by mass or less of unsaturated carboxylic acid ester monomer units. Furthermore, the dispersed particles of the rubber-modified styrenic resin (A) have a particle diameter of 0.1 μm or more and 2.0 μm or less, and the rubber-like elastic body contains a styrene-conjugated diene copolymer and has a rubber-like elasticity. The solid content is 1% by mass or more and 20% by mass or less with respect to 100% by mass of the rubber-modified styrene resin (A). In the styrene copolymer resin (B), the total content of styrene monomer units, unsaturated carboxylic acid monomer units, and unsaturated carboxylic acid ester monomer units was 100% by mass. When the styrene-based monomer unit is 54% by mass or more and 96% by mass or less, the unsaturated carboxylic acid-based monomer unit is 4% or more and 16% by mass or less, and the unsaturated carboxylic acid ester-based monomer unit is 0% by mass % or more and 30 mass % or less. Furthermore, the styrene copolymer resin (C) contains 10 mass of styrene monomer units when the total content of styrene monomer units and unsaturated carboxylic acid ester monomer units is 100% by mass. % or more and 90 mass % or less, and contains 10 mass % or more and 90 mass % or less of unsaturated carboxylic acid ester monomer units. In the present embodiment, these configurations make it possible to obtain a resin composition having translucency, heat resistance, rigidity and impact resistance.

<Rubber-modified styrene resin (A)>
The rubber-modified styrenic resin (A) contained in the styrenic resin composition of the present embodiment contains a rubber-like elastomer as dispersed particles, and contains styrene-based monomer units and unsaturated carboxylic acid ester-based monomer units. as a continuous phase.

The continuous phase contains 20 to 70% by mass of styrene-based monomer units and an unsaturated carboxylic acid when the content of styrene-based monomer units and unsaturated carboxylic acid ester-based monomer units is 100% by mass. It is formed of a copolymer (a) containing 30 to 80% by mass of ester-based monomer units. By containing the styrene-based monomer unit and the unsaturated carboxylic acid ester-based monomer unit, excellent transparency and rigidity can be imparted to the molded product.

Styrenic monomers of the copolymer (a) include, for example, styrene, α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, ethylstyrene, isobutylstyrene, t-butylstyrene, o-bromstyrene, m-bromstyrene, p-bromstyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene and the like. Among these, styrene is preferred because of its good reactivity and ease of polymerization.

The content of the copolymer (a) is 20 to 70 mass of the styrene monomer when the content of the styrene monomer unit and the unsaturated carboxylic acid ester monomer unit is 100% by mass. %, preferably 30 to 70% by mass. That is, in the range of 20% by mass or more, the composition has good fluidity when melted and excellent moldability. The amount of polymer is increased, and the molded product has excellent rigidity and chemical resistance.

Examples of unsaturated carboxylic acid ester-based monomers for the copolymer (a) include alkyl methacrylates such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, and butyl methacrylate, methyl acrylate, and ethyl acrylate. , propyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate. Among these, methyl methacrylate is particularly preferable because it has a large effect of improving the rigidity of molded articles. In addition, from the viewpoint of the transparency and impact resistance of the molded product, and the moldability during sheet film formation and thermoforming of the molded product, it is possible to use methyl methacrylate together with other unsaturated carboxylic acid ester monomers. (i.e., containing at least two unsaturated carboxylic acid ester-based monomers, one of which can be methyl methacrylate), more specifically, a combination of butyl acrylate and methyl methacrylate can do.

The content of the copolymer (a) is, when the content of the styrene-based monomer unit and the unsaturated carboxylic acid ester-based monomer unit is 100% by mass, the unsaturated carboxylic acid ester-based monomer It is contained in a proportion of 30 to 80% by mass, preferably 30 to 70% by mass. That is, in the range of 30% by mass or more, the molded product has excellent rigidity and chemical resistance. In addition, when the content is 80% by mass or less, the fluidity of the composition when melted becomes good, resulting in excellent moldability. When methyl methacrylate is used in combination with other unsaturated carboxylic acid ester monomers, the content of the other unsaturated carboxylic acid ester monomers is the same as the styrene monomer unit and the unsaturated carboxylic acid ester monomer. It is preferably 0.5 to 20% by mass, more preferably 2 to 17% by mass, based on 100% by mass of the content of acid ester-based monomer units. By setting the amount in such a range, it is possible to satisfy the transparency and impact resistance of the molded product, and the moldability during sheet film formation and thermoforming of the molded product.

The contents of the styrene-based monomer units, the unsaturated carboxylic acid-based monomer units, etc. in the rubber-modified styrene-based resin (A) are determined by nuclear magnetic resonance ( ¹³ C- It can be obtained from the integral ratio of the spectrum when measured with an NMR) measuring device.

The dispersed particles contain a rubber-like elastomer containing a styrene-conjugated diene copolymer. It is obtained by polymerizing a monomer and an unsaturated carboxylic acid ester monomer. The dispersed particles have a portion where the copolymer (a) is graft-copolymerized with the rubber-like elastic material on the particle surface. At this time, the graft copolymer portion on the particle surface of the dispersed particles can be entangled with the continuous phase.

The styrene-conjugated diene copolymer is obtained by copolymerizing a styrene-based monomer and a diene-based monomer. Various monomers exemplified as monomers can be used. Styrene is particularly preferred. Diene-based monomers include butadiene, chloroprene, isoprene, 1,3-pentadiene, and the like, but butadiene is preferred because of its excellent reactivity with styrene-based monomers. The structure of the styrene-conjugated diene copolymer may be either a random structure or a block structure.

The content of the rubber-like elastomer is 1 to 20% by mass, more preferably 1 to 15% by mass, based on 100% by mass of the rubber-modified styrene resin (A). When the content of the comb-like elastic material is 1% by mass or more, a strength reinforcing effect can be exhibited. ensure preferred. Moreover, by setting the value within such a range, it is possible to impart transparency, impact resistance, and rigidity to the composition. The content of the rubber-like elastic material can be measured by the measuring method described in the Examples section below.

The dispersed particles have a particle size of 0.1 to 2.0 μm, preferably 0.2 to 1.8 μm, more preferably 0.2 to 1.2 μm. By setting the particle size to 0.1 μm or more, the effect of reinforcing strength can be easily exhibited, and by setting the particle size to 2.0 μm or less, transparency can be easily ensured. The particle diameter of the dispersed particles can be measured by the measurement method described in the Examples section below.

In the rubber-modified styrenic resin (A), the swelling index of the dispersed particles with toluene at 25° C. is preferably 8 to 19, more preferably 9 to 16, still more preferably 10 to 14. . The toluene-insoluble content of the rubber-modified styrenic resin (A) at 25° C. is preferably 10 to 35% by mass, more preferably 12 to 30% by mass, and still more preferably 14 to 25% by mass. . The toluene-insoluble matter content and the toluene swelling index are measured as follows.

・Method for measuring toluene insoluble content and toluene swelling index 1 g of rubber-modified styrenic resin (A) was accurately weighed in a precipitation tube (this weight is defined as W1), 20 mL of toluene was added, and the mixture was shaken at 23°C for 2 hours. After that, it is centrifuged at 10° C. or below and 20000 rpm for 60 minutes in a centrifuge (himac, CR-20 (rotor: R20A2) manufactured by Hitachi, Ltd.). The supernatant was removed by decantation by slowly tilting the sedimentation tube to about 45 degrees and holding it for about 3 seconds. 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. is accurately weighed (this mass is defined as W3).
The swelling index and content of the toluene-insoluble matter are determined by the following formula.
Toluene-insoluble content (% by mass) = ((W3)/(W1)) x 100
Swelling index of toluene insolubles = (W2/W3)

The content (%) of the styrene structural unit in the styrene-conjugated diene copolymer is preferably 33 to 55% from the viewpoint of the balance between impact strength and transparency. By setting the content to 55% or less, a molded product having a relatively high conjugated diene content and excellent impact resistance can be obtained. In addition, by setting the content to 33% or more, the melt fluidity of the styrene-conjugated diene copolymer is improved, making it easier to adjust the viscosity with the matrix, and the fluidity of the composition when melted and the molded product. The balance with the heat resistance of is good.

In the above styrene-conjugated diene copolymer, the ratio of 1,2-vinyl bonds among the unsaturated bonds based on the conjugated diene is preferably 14 to 35%. When the ratio is within this range, the grafting ratio of the graft copolymerized portion on the particle surface and the degree of cross-linking of the rubber-like particles are well balanced, and the impact strength is improved. In this case, the rest of the 1,2-vinyl bonds form cis and trans bonds.

In the styrenic resin composition of the present embodiment, when the total content of the rubber-modified styrenic resin (A) and the styrenic copolymer resin (B) is 100% by mass, the content of the rubber-modified styrenic resin (A) The amount is 50% by mass or more and less than 100% by mass, preferably 60 to 98% by mass, more preferably 70 to 95% by mass. By making the content of the rubber-modified styrenic resin (A) 50% by mass or more, the impact resistance can be improved, and by making it less than 100% by mass, the heat resistance can be enhanced. Further, in the styrene resin composition, by setting the content of the rubber-modified styrene resin (A) within the above range and the content of the styrene copolymer resin (B) within the range described below, Appropriate translucency can be obtained.

In the present embodiment, the melt mass flow rate (MFR) of the rubber-modified styrenic resin (A) is preferably 0.5 to 7 g/10 minutes, more preferably 0.7 to 5 g/10 minutes, still more preferably 1 to 5 g/10 minutes. 4 g/10 minutes. By setting the melt mass flow rate in the range of 0.5 to 7 g/10 minutes, a styrene resin composition having excellent moldability during sheet film formation and molded product thermoforming 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 rubber-modified styrenic resin (A) is preferably 80° C. or higher, more preferably 85° C. or higher, and even more preferably 85° C. or higher, because the molded article may be dried with hot air during sterilization. is above 90°C. Moreover, there is no particular upper limit for the Vicat softening temperature.
The Vicat softening temperature can be measured according to JIS K7206.

The rubber-modified styrenic resin (A) preferably has a haze of 0.5 to 5%, more preferably 0.7 to 4%, and even more preferably 0.7 to 4% when molded into a flat plate (molded article) having a thickness of 1 mm. is 1-3%. Within this range, appropriate transparency of the rubber-modified styrenic resin (A) can be obtained. Haze can be measured according to JIS K7136.

The rubber-modified styrenic resin (A) preferably has a total light transmittance of 85 to 91% when molded into a flat plate (molded product) having a thickness of 2 mm. Within this range, appropriate transparency of the rubber-modified styrenic resin (A) can be obtained. The total light transmittance can be measured according to JIS K7361-1.

A method for polymerizing the rubber-modified styrenic resin (A) will be described below. The rubber-modified styrenic resin (A) is not particularly limited, and methods frequently used in the production of rubber-reinforced polystyrene (HIPS resin) can be used. Specifically, a rubber-like elastomer is dissolved in a raw material solution containing a styrene-based monomer, an unsaturated carboxylic acid ester-based monomer, a polymerization solvent, and a polymerization initiator, and the raw material solution in which the rubber-like elastomer is dissolved is stirred with a stirrer. It is supplied to a reactor and polymerized. The particle size of the dispersed particles is controlled by a commonly used method, namely, by changing the number of stirring blades. Further, as a method for maintaining transparency, a general method, for example, a method of adding a monomer as necessary during the polymerization or a method of continuously adding a monomer is used.

The content of the rubber-like elastomer can be achieved by adjusting the raw materials and the polymerization rate so that the target content is achieved. It can also be achieved by mixing with a rubber-like elastomer-free styrenic resin prepared separately.

At this time, it is also possible to use a polymerization solvent such as ethylbenzene, toluene, or xylene. Organic peroxides commonly used in the polymerization of rubber-modified styrenic resins may be used or may be added in the course of the polymerization. As the polymerization method, a bulk polymerization method or a solution polymerization method commonly used in the production of rubber-modified styrenic resins is used. Either a batch polymerization method or a continuous polymerization method can be used.

The polymerization solution leaving the reactor is led to a recovery device. As the recovery device, devices commonly used in the production of styrenic resins, such as flash tank systems and extruders with multistage pents, can be used. As for the operating conditions, the same conditions as in the production of styrenic resin can be used.

Additives commonly used in rubber-modified styrenic resins, such as antioxidants, lubricants, plasticizers, colorants, antistatic agents, at any stage before or after recovery of unreacted monomers and/or polymerization solvent. etc. can be added.

<Styrene-based copolymer resin (B)>
The styrene-based copolymer resin (B) 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 styrene-based copolymer resin (B) is 100 mass. %, the content of the styrenic monomer is 54 to 96 mass %, more preferably 74 to 92 mass %, more preferably 77 to 85 mass %. By making this content 54% by mass or more, the fluidity of the resin is improved, and on the other hand, by making it 96% by mass or less, the unsaturated carboxylic acid-based monomer unit and the unsaturated carboxylic acid ester-based monomer Body units can be present in any desired amount to obtain the desired effect of those monomers.

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 handleability.

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 styrene-based copolymer resin (B) 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. By setting the content to 4% by mass or more, the heat resistance can be further improved. The appearance can be improved, and the fluidity and mechanical properties of the styrenic copolymer resin (B) can be improved.

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 styrene-based copolymer resin (B) of the present embodiment, the unsaturated carboxylic acid ester-based monomer is converted into an unsaturated carboxylic acid-based monomer through intermolecular interaction with the unsaturated carboxylic acid-based monomer. can be used to suppress the dehydration reaction of the styrene-based copolymer resin (B) and to improve the mechanical strength of the styrene-based copolymer resin (B). Furthermore, the inclusion 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 styrene-based copolymer resin (B) is 100% by mass, The content of the unsaturated 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. . When the content is 30% by mass or less, the fluidity of the copolymer resin (B) is further improved, and the water absorption tends to be lowered.

The styrene copolymer resin (B) 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 (B).

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

In the present embodiment, the melt mass flow rate (MFR) of the styrene copolymer resin (B) is preferably 0.3 to 4.0 g/10 minutes, more preferably 0.5 to 2.0 g/10 minutes, and further It is 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 styrene copolymer resin (B) is preferably 110° C. or higher, more preferably 119° C. or higher, and even more preferably 119° C. or higher, because the molded article may be dried with hot air during sterilization. is above 122°C. Moreover, there is no particular upper limit for the Vicat softening temperature.
The Vicat softening temperature can be measured according to JIS K7206.

In the present embodiment, the number average molecular weight (Mn) of the styrene copolymer resin (B) is preferably 40,000 to 200,000, more preferably 50,000 to 150,000, and still more preferably 70,000 to 120,000. is.
In the present embodiment, the weight average molecular weight (Mw) of the styrene copolymer resin (B) 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 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 (B) can be measured by gel permeation chromatography in terms of polystyrene standards.

The styrene-based copolymer resin (B) 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, various physical properties of the styrene-based copolymer resin (B) 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 rubber-modified styrene resin (A) and the styrene copolymer resin (B) is 100% by mass, the content of the styrene copolymer resin (B) The amount is more than 0% by mass and 50% by mass or less, preferably 2 to 40% by mass, more preferably 5 to 30% by mass. By making the content of the styrene-based copolymer resin (B) more than 0% by mass, the heat resistance can be improved, and by making it 50% by mass or less, the impact resistance can be improved.

The method of polymerizing the styrene-based copolymer resin (B) 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 styrene-based copolymer resin (B), 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 styrene-based copolymer resin (B) of the present embodiment will be described.
When the raw materials for polymerization are polymerized to obtain the styrenic copolymer resin (B), the raw material composition for polymerization is typically made to contain 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, 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 styrene copolymer resin (B). 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 for the styrene-based copolymer resin (B). 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 styrene copolymer resin (B) is preferably as low as possible, more preferably 0.7% by mass or less, and even more preferably 0.6% by mass. It is below. 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 (B) 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 (B) of the present embodiment. Examples include stabilizers, antioxidants, ultraviolet absorbers, lubricants, release agents, plasticizers, antiblocking agents, antistatic agents, antifogging agents, mineral oils, and strength improving agents. The content of these various additives is preferably 10% by mass or less with respect to 100% by mass of the styrene copolymer resin (B).
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 styrenic copolymer resin (B) is not particularly limited, and may be appropriately selected according to the polymerization method 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.

<Styrene-based copolymer resin (C)>
The styrene copolymer resin (C) that can be included in the styrene resin composition of the present embodiment is It is a copolymer containing 0 parts by mass or more and 20 parts by mass or less.
Further, the styrene copolymer resin (C) contains 10 to 10 styrene monomer units when the total content of styrene monomer units and unsaturated carboxylic acid ester monomer units is 100% by mass. It contains 90% by mass, and contains 10 to 90% by mass of unsaturated carboxylic acid ester-based monomer units.

The content of the styrene copolymer resin (C) is 0 parts by mass or more and 20 parts by mass or less with respect to a total of 100 parts by mass of the rubber-modified styrene resin (A) and the styrene copolymer resin (B). When the styrene copolymer resin (C) is contained, it is preferably 2 to 18 parts by mass, more preferably 5 to 15 parts by mass. By setting the content of the styrene-based copolymer resin (C) to more than 0 parts by mass, the translucency of the molded article can be made more moderate. Moreover, by setting the content of the styrene-based copolymer resin (C) to 20 parts by mass or less, it is possible to maintain the impact resistance while increasing the rigidity of the molded article. When the styrene-based copolymer resin (C) is not contained (that is, the content is 0 parts by mass), it is possible to save time and effort in forming the sheet.

Specifically, the styrene-based copolymer resin (C) is a copolymer obtained by polymerizing a styrene-based monomer and an unsaturated carboxylic acid ester-based monomer, and the polymerization method is not particularly limited. A known bulk polymerization method, solution polymerization method, bulk-suspension polymerization method, suspension polymerization method, emulsion polymerization method, and the like can be employed. Moreover, it may be either a batch polymerization method or a continuous polymerization method. Styrenic monomers specifically include styrene, α-alkyl-substituted styrenes such as α-methylstyrene, core alkyl-substituted styrenes such as o-methylstyrene, m-methylstyrene, p-methylstyrene, p-methylstyrene, - t-butyl styrene and the like. These styrene-based monomers may be used alone, or two or more of them may be used in combination. Among them, styrene is preferred.

Further, unsaturated carboxylic acid ester-based monomers include methyl methacrylate, ethyl methacrylate, methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, and the like. Among them, methyl methacrylate and n-butyl acrylate are preferred. These (meth)acrylic acid esters may be used alone, or two or more of them may be used in combination. It is preferable to adjust the type and amount of the (meth)acrylic acid ester so that the Vicat softening point is 90° C. or higher in the copolymerization with styrene.

In the present embodiment, the styrene-based copolymer resin (C) specifically includes a styrene-methyl methacrylate copolymer resin, a styrene-methyl methacrylate-n-butyl acrylate copolymer resin, and a styrene-ethyl methacrylate copolymer resin. It is preferably a polymer resin, α-styrene-methyl methacrylate copolymer resin, styrene-n-butyl acrylate copolymer resin, or the like. and (meth) copolymerizable vinyl-based monomers other than acrylic esters, such as acrylonitrile, within 10 parts by weight per 100 parts by weight of the total of styrene-based monomers and unsaturated carboxylic acid ester-based monomers can be included if

In the present embodiment, when the styrene copolymer resin (C) is polymerized, the polymerization initiators are 2,2′-azobisisobutyronitrile, 2,2′-azobis(2-methylbutyronitrile), 1 , 1′-Azobis(1-cyclohexanecarbonitrile) and other known azo compounds, 1,1-bis(t-butylperoxy)cyclohexane, 1,1-bis(t-butylperoxy)-3,3,5 -trimethylcyclohexane, di-t-butyl peroxide, dicumyl peroxide, octanoyl peroxide, lauroyl peroxide, diisopropylperoxydicarbonate, di-n-propylperoxydicarbonate, t-butylperoxypivalate, t-butylperoxy-3, Known organic peroxides such as 3,5-trimethylhexanoate, t-butyl hydroperoxide and 2,2-bis(4,4-di-t-butylperoxycyclohexyl)propane are preferably used. When the amount of the azo compound or organic peroxide used is small, or when radical thermal polymerization is performed without using them, the amount of dimers and trimers in the resulting resin may increase. In addition, known molecular weight modifiers such as α-methylstyrene linear dimer, n-dodecylmercaptan, t-dodecylmercaptan, 1-phenyl-2-fluorene, dipentene, mercaptans such as chloroform, terpenes, halogen compounds, terpinolene, etc. of turpentines may be added as necessary. Further, a known cross-linking agent such as divinylbenzene may be added for polymerization.

In this embodiment, for example, toluene, xylene, aromatic hydrocarbons such as ethylbenzene, dialkyl ketones such as methyl ethyl ketone, and the like may be used as the polymerization solvent, if necessary. Each of them may be used alone, or two or more thereof may be used in combination. Furthermore, other solvents such as aliphatic hydrocarbons can be mixed with the aromatic hydrocarbons as long as they do not reduce the solubility of the polymerization product. These solvents are preferably used in an amount not exceeding 25% by mass based on the monomers. If the solvent content exceeds 25% by mass, the polymerization rate is significantly lowered and the impact strength of the resulting resin is greatly lowered. Also, a large amount of energy is required to recover the solvent. The solvent may be added after the polymerization progresses and the viscosity becomes relatively high, or it may be added before the polymerization. It is preferable from the point of view of polymerization temperature control that the quality is easily uniformized.

In the present embodiment, the devolatilization step is also not particularly limited. When the styrene-based monomer and the unsaturated carboxylic acid ester-based monomer are polymerized by bulk polymerization, the unreacted monomer is preferably 50% by mass, more preferably 40% by mass or less. In order to proceed with the polymerization and remove the volatile matter such as the monomer, devolatilization treatment is performed by a known method. This devolatilization step is for removing unreacted substances and/or solvent from the reaction product after the polymerization reaction. Conventional devolatilizing equipment such as extruders can be used. The temperature of the devolatilization treatment is usually about 190 to 280° C., and the pressure of the devolatilization treatment is usually about 1 to 100 torr (torr), preferably 1 to 50 torr, more preferably 1 torr. ~10 torr. As the devolatilization method, it is preferable to remove the volatile matter by reducing the pressure under heating, or to remove the volatile matter through an extruder designed for the purpose of removing the volatile matter.

The styrene copolymer resin (C) of the present invention contains 10 to 90% by mass of styrene monomer and 10 to 90% by mass of unsaturated carboxylic acid ester monomer, preferably 20 to 80% by mass of styrene monomer. % and unsaturated carboxylic acid ester-based monomers in an amount of 20 to 80% by weight, more preferably styrene-based monomers in an amount of 30 to 70% by weight and unsaturated carboxylic acid ester-based monomers in an amount of 30 to 70% by weight. If the styrene-based monomer exceeds 90% by mass, the content of the unsaturated carboxylic acid ester-based monomer in the styrene-based copolymer resin (C) decreases, and the unsaturated carboxylic acid ester-based monomer , ie impact resistance and translucency are inferior. Moreover, when the styrene-based monomer is less than 10% by mass, the translucency of the composition deteriorates, which is not preferable.

In the present embodiment, the melt mass flow rate (MFR) of the styrenic copolymer resin (C) is preferably 0.5 to 7 g/10 min, more preferably 0.7 to 6 g/10 min, still more preferably 1 to 5 g/10 minutes. By setting the melt mass flow rate in the range of 0.5 to 7 g/10 minutes, a styrene resin composition having excellent moldability during sheet film formation and molded product thermoforming 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 styrenic copolymer resin (C) is preferably 98° C. or higher, more preferably 100° C. or higher, from the viewpoint of the use environment in which the molded article is dried with hot air during sterilization. . Moreover, there is no particular upper limit for the Vicat softening temperature.
The Vicat softening temperature can be measured according to JIS K7206.

<Other ingredients>
Various additives that are commonly used in styrene resins may be appropriately added to the styrene resin composition of the present embodiment. Examples include stabilizers, antioxidants, ultraviolet absorbers, lubricants, release agents, plasticizers, antiblocking agents, antistatic agents, antifogging agents, mineral oils, and strength improving agents. 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. A method of melting and kneading may be mentioned.
The content of the additive in the styrenic resin composition may be 10% by mass or less.

<Characteristics of styrene resin composition>
The Vicat softening temperature of the styrene-based resin composition is 88° C. or higher, preferably 92° C. or higher, and more Preferably, it is 95°C or higher. Although there is no particular upper limit for the Vicat softening temperature, it is necessary to ensure a high Vicat softening temperature as well as practical strength and moldability as a molded product. The Vicat softening temperature can be measured according to JIS K7206.

The styrenic resin composition preferably has a haze of 5 to 70%, more preferably 10 to 60%, and still more preferably 20 to 50% when molded into a flat plate (molded article) having a thickness of 1 mm. . Within this range, it is possible to obtain an appropriate translucency of the molded article. Haze can be measured according to JIS K7136.

The styrene resin composition preferably has a total light transmittance of 65% or more and less than 90%, more preferably 70% or more and less than 90%, still more preferably when molded into a flat plate (molded article) having a thickness of 2 mm. is 75% or more and less than 90%. Within this range, it is possible to obtain an appropriate degree of translucency that allows the contents to be visually recognized. The total light transmittance can be measured according to JIS K7361-1.

The impact strength of the styrene-based resin composition is preferably 2.4 kJ/m ² or more, more preferably 3.5 kJ/m ² or more, still more preferably 4.5 kJ/m ² or more. Within this range, the impact resistance of the molded product can be ensured. The impact strength is Charpy impact strength with a notch and can be measured according to JIS K7111.

The flexural modulus of the styrene-based resin composition is preferably 2200 MPa or higher, more preferably 2400 MPa or higher, and still more preferably 2600 MPa or higher. Within this range, the rigidity of the molded product can be ensured. The flexural modulus can be measured according to JIS K7171.

[Method for producing styrene resin composition]
The styrene resin composition of the present embodiment includes, for example, the above-described rubber-modified styrene resin (A), styrene copolymer resin (B), styrene copolymer resin (C) as necessary, additives, and the like. , a single-screw extruder, a twin-screw extruder, a Banbury mixer, and other known kneading machines.

[Sheet]
The sheet of this embodiment is a sheet having a layer (hereinafter also referred to as a styrene resin composition layer) formed from the styrene resin composition of the embodiment according to the present invention described above. The sheet of the present embodiment may be a single layer (one styrene-based resin composition layer), or may be formed of multiple layers. The styrene resin composition layer in the sheet contains the styrene resin composition even if it is a layer formed from a single sheet (unfoamed) obtained without foaming the styrene resin composition as described later. A layer formed of a single sheet obtained by foaming may also be used.
When it is a non-foamed layer, it is not particularly limited, but it can be multi-layered with a layer made of a styrene-based resin such as polystyrene resin. In addition, it may be used in a multi-layered manner with a resin other than styrene-based resins, and examples of resins other than styrene-based resins include PET resin, nylon resin, ethylene-vinyl alcohol copolymer resin, polyvinyl alcohol resin, and the like. Further, an adhesive layer may be provided between each layer.
In the sheet of the present embodiment, it is preferable to further include a barrier layer having gas barrier properties. As the barrier layer, for example, an ethylene-vinyl alcohol copolymer resin has gas barrier properties, so it is preferable to use it as the barrier layer. is.
Further, when the styrene-based resin composition layer in the sheet is a foamed layer, the styrene-based resin composition layer is not particularly limited. Can be layered and multi-layered. Specifically, a multilayer structure can be formed by further laminating a film of the above resin on the foamed styrene-based resin composition layer. The type of film to be used is not particularly limited, but examples thereof include polystyrene, polypropylene, and laminated films of polypropylene/polystyrene. Further, an adhesive layer may be provided between each layer.

The styrene-based resin composition layer is preferably a non-foamed layer from the viewpoint of obtaining appropriate translucency, but may be a foamed layer. In the sheet of the present embodiment, the styrene-based resin composition layer can be obtained by manufacturing a single sheet of the styrene-based resin composition before sheet formation. can use a commonly known method. For example, as a method for producing a single sheet of a non-foamed styrenic resin composition layer, extrusion is performed with a single or twin screw extruder equipped with a T-die, and then a single sheet is drawn with a single or biaxial stretching machine. A method using an apparatus and the like can be mentioned. Examples of the method for producing the foamed sheet include a method using an extrusion foam molding machine equipped with a T-die or a circular die. In addition, when the sheet of the present embodiment has one layer, the single sheet described above is the sheet of the present embodiment.

A non-foamed single sheet, for example, preferably has a thickness of about 0.1 to 4.0 mm from the viewpoint of rigidity and thermoforming cycle. In addition, a single sheet may be formed only by normal roll stretching at a low magnification, but in particular, a sheet stretched by a roll by about 1.3 to 7 times and then by a tenter by about 1.3 to 7 times is formed. It is preferable in terms of strength.

The foamed single sheet preferably has a thickness of 0.5 mm to 5.0 mm, an apparent density of 50 g/L to 300 g/L, and a basis weight of 80 g/m ² to 300 g/m ² . is preferred.

In the case of producing a foamed unitary sheet, as a foaming agent and foaming nucleating agent for extrusion foaming, commonly used substances 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 single 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]
The molded article of this embodiment is a molded article formed from the sheet of the embodiment according to the present invention described above. The method for producing the molded article of the present embodiment is not particularly limited, but when the styrene-based resin composition layer of the sheet is a non-foamed layer, for example, it is molded by vacuum molding, pressure molding, etc. Lid materials, containers for prepared dishes, and beverage containers can be manufactured. Further, when the styrene-based resin composition layer of the sheet is a foamed layer, it can be formed into a container such as a tray by, for example, vacuum forming.

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 of the resin compositions in Examples and Comparative Examples are as follows.

[Analysis/evaluation method]
(1) Total light transmittance, haze From the styrenic resin compositions obtained in the following examples and comparative examples, injection molding was performed using a mirror-finished mold for flat plate molding, and the thickness was 1 mm and 2 mm. Using the flat plate, the total light transmittance (%) was measured according to JIS K7361-1, and the haze (%) was measured according to JIS K7136.

(2) Vicat softening temperature Vicat softening temperature (°C) of the styrenic resin compositions obtained in the following examples and comparative examples was measured according to JIS K7206. The load was 49N, and the heating rate was 50°C/h.

(3) Flexural Modulus From the styrene resin compositions obtained in the following examples and comparative examples, injection-molded pieces were produced at 220°C according to JIS K 7152, and the molded pieces were molded according to JIS K7171. The flexural modulus (MPa) of (test piece) was measured. The test speed was 2 mm/min.

(4) Charpy impact test From the styrenic resin compositions obtained in the following examples and comparative examples, injection molded pieces were produced at 220 ° C. in accordance with JIS K 7152, and the molded pieces were molded in accordance with JIS K7111. Charpy impact strength (kJ/m ² ) of (test piece) was measured. The test condition was 1 eA.

(5) Content of styrene-based monomer units, unsaturated carboxylic acid-based monomer units, and unsaturated carboxylic acid ester-based monomer units Rubber-modified styrene-based resin (A), styrene-based copolymer resin (B ), the content (mass%) 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 (C) is The resin composition was quantified from the integral ratio of the spectrum measured with a 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 of 60°C, observation core of ¹³ °C, number of accumulations of 20,000 times, repetition time of 45 seconds

(6) Rubber-Like Elastic Content The rubber-like elastic content (% by mass) of the rubber-modified styrenic resin (A) was measured as follows. 4 g of rubber-modified styrenic resin (A) was precisely weighed in a volumetric flask (this mass is W), 75 mL of chloroform was added and well dispersed, and then 18 g of iodine monochloride was dissolved in 1000 mL of carbon tetrachloride. 20 mL was added, stored in a cool and dark place, chloroform was added after 8 hours, and adjusted to the marked line. 25 mL of this was collected, 60 mL of a solution of 10 g of potassium iodide 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
Based on the styrene/butadiene ratio and the content of the component derived from the conjugated diene monomer in the rubber-like elastomer used in the rubber-modified styrenic resin (A), the content of the rubber-like elastomer was calculated.

(7) Melt flow rate (MFR)
The melt flow rate (MFR) (g/10 min) of rubber-modified styrene resin (A), styrene copolymer resin (B) and styrene copolymer resin (C) was measured according to ISO 1133 (200 °C, load 49N).

(8) Measurement of particle size of dispersed particles The average particle size (μm) of the dispersed particles of the rubber-modified styrenic resin (A) is determined by taking a transmission electron microscope photograph using an ultra-thin section method. 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 having a particle diameter Di. Di is the average value of the major and minor diameters of the particles.)

(9) Toluene Insoluble Content and Toluene Swelling Index The toluene insoluble content and toluene swelling index of the rubber-modified styrenic resin (A) were measured as follows.
Accurately weigh 1 g of resin in a sedimentation tube (this mass is defined as W1), add 20 ml of toluene and shake at 23° C. for 2 hours. : R20A2)) and centrifuged at 20000 rpm for 60 minutes at 10°C or lower. The supernatant was removed by decantation by slowly tilting the sedimentation tube to about 45 degrees and holding it for about 3 seconds. 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)

(10) Number average molecular weight, weight average molecular weight and Z average molecular weight The number average molecular weight (Mn), weight average molecular weight (Mw), Z average molecular weight (Mz) and molecular weight distribution (Mz/Mw) of the styrene copolymer resin (B) ) was measured under the following conditions using gel permeation chromatography (GPC).
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

[material]
-Rubber-modified styrene resin (A)-
·Rubber-modified styrene resin (A-1): Produced using a polymerization apparatus in which two reactors equipped with a stirrer were connected in series, followed by an extruder equipped with a vacuum vent. 44.8 parts by mass of styrene, 4.6 parts by mass of butyl acrylate, 35.8 parts by mass of methyl methacrylate, BS type (B: butadiene block, S: styrene block) as a rubber-like elastic body, with a styrene content of 38 parts by mass %, 2.8 parts by mass of ethylbenzene, and 0.01 part by mass of 1,1-bis(t-butylperoxy)cyclohexane. The polymerization temperature in the reactor was 140° C. and the stirring was 50 rpm. Unreacted monomers were devolatilized from the polymer solution using an extruder with a vacuum vent at a set temperature of 200 to 250° C. under a reduced pressure of 10 torr.
100 parts by mass of the obtained rubber-modified styrene resin and 0.05 parts by mass of polydimethylsiloxane were blended and granulated with a single-screw extruder. Table 1 shows the physical properties of the obtained rubber-modified styrene resin.

・Rubber-modified styrene resin (A-2): The raw material solution supplied to the reactor is composed of 47.8 parts by mass of styrene, 42 parts of methyl methacrylate, and BS type as a rubber-like elastic body (B: butadiene block, S: The procedure was the same as for the production of the rubber-modified styrene resin (A-1), except that 7.4 parts by mass of a rubber-like elastic body having a styrene content of 38% by mass was used as a styrene block). Table 1 shows the physical properties of the obtained rubber-modified styrene resin.

・Rubber-modified styrenic resin (A-3): The raw material solution supplied to the reactor is composed of 41 parts by mass of styrene, 4.1 parts by mass of butyl acrylate, 33.5 parts by mass of methyl methacrylate, and BS type as a rubber-like elastic body. (B: butadiene block, S: styrene block), 18.6 parts by mass of a rubber-like elastic body having a styrene content of 38% by mass, and the stirring speed of the reactor was changed to 60 rpm. The procedure was the same as for the preparation of resin (A-1). Table 1 shows the physical properties of the obtained rubber-modified styrene resin.

- Styrene-based copolymer resin (B) -
Styrene-based copolymer resin (B-1): 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 1,1-bis(t- A polymerization raw material composition liquid consisting of 0.025 parts by mass of butylperoxy)cyclohexane was added at a rate of 0.8 L/hour to a complete mixing reactor having a capacity of 3.6 L, and further volatilization of unreacted monomers, polymerization solvent, etc. It was continuously supplied to a devolatilization device connected to a single-screw extruder for removing fractions. 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. Table 2 shows the physical properties of the obtained styrenic copolymer resin.

・ Styrene-based copolymer resin (B-2): The composition of the polymerization raw material composition liquid is 48.8 parts by mass of styrene, 8.2 parts by mass of methacrylic acid, 17.0 parts by mass of methyl methacrylate, and 26.0 parts by mass of ethylbenzene. , and 0.025 parts by mass of 1,1-bis(t-butylperoxy)cyclohexane, and the reactor temperature was set to 130° C., and the same operation as in the production of the styrenic copolymer resin (B-1) was performed. Table 2 shows the physical properties of the obtained styrenic copolymer resin.

- Styrene-based copolymer resin (C) -
- Styrene-based copolymer resin (C-1): polymerization of 40 parts by mass of styrene, 60 parts by mass of methyl methacrylate, 0.35 parts by mass of t-butyl peroxyisobutyrate, and 0.15 parts by mass of n-dodecyl mercaptan 3,500 g of the raw material composition liquid was put into a 10-liter separable flask charged with 6,000 g of a 0.5% aqueous solution of sodium polymethacrylate, and polymerized at 80.degree. After about 5 hours, the reaction temperature was raised to 97° C. and polymerization was carried out for 2 hours, followed by filtration, washing and drying to obtain a granular polymer. This granular polymer was pelletized. Table 3 shows the physical properties of the obtained styrenic copolymer resin.

・ Styrene-based copolymer resin (C-2): The same operation as for the production of styrene-based copolymer resin (C-1), except that the polymerization raw material composition liquid was 70 parts by mass of styrene and 30 parts by mass of methyl methacrylate. did. Table 3 shows the physical properties of the obtained styrenic copolymer resin.

[Examples 1 to 13, Comparative Examples 1 to 4]
Rubber-modified styrene resin (A), styrene copolymer resin (B), and styrene copolymer resin (C) having the compositions shown in Table 4 were extruded using a 30 mm diameter twin-screw extruder (manufactured by Soken Co., Ltd.). The mixture was kneaded at 230° C. and 120 rpm, and then pelletized to obtain a styrenic resin composition.
Table 4 shows the evaluation results of the obtained styrenic resin composition.

As shown in Table 4, Examples 1 to 13 in which the content of the rubber-modified styrene resin (A), the styrene copolymer resin (B), and the styrene copolymer resin (C) were set to a predetermined content range It can be seen that it has good translucency, heat resistance, rigidity and impact resistance as compared with the comparative examples excepted.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a resin composition, sheet and molded article having translucency, heat resistance, rigidity and impact resistance.

Claims (6)

50% by mass of the rubber-modified styrenic resin (A) with respect to a total of 100% by mass of the rubber-modified styrenic resin (A) containing a rubber-like elastic material as dispersed particles and the styrene-copolymer resin (B) More than 100% by mass and more than 0% by mass and less than 50% by mass of the styrene copolymer resin (B), and the styrene copolymer resin (C) is combined with the rubber-modified styrene resin (A) and the styrene Containing 0 parts by mass or more and 20 parts by mass or less with respect to a total of 100 parts by mass with the system copolymer resin (B),
The continuous phase of the rubber-modified styrene resin (A) contains styrene monomer units when the content of styrene monomer units and unsaturated carboxylic acid ester monomer units is 100% by mass. A copolymer (a) containing 20% by mass or more and 70% by mass or less and 30% by mass or more and 80% by mass or less of unsaturated carboxylic acid ester monomer units,
The dispersed particles of the rubber-modified styrenic resin (A) have a particle diameter of 0.1 μm or more and 2.0 μm or less, and the rubber-like elastic body contains a styrene-conjugated diene copolymer and The content of the elastic body is 1% by mass or more and 20% by mass or less with respect to 100% by mass of the rubber-modified styrene resin (A),
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 styrene-based copolymer resin (B) is 100% by mass, , the styrene-based monomer unit is 54% by mass or more and 96% by mass or less, the unsaturated carboxylic acid-based monomer unit is 4% by mass or more and 16% by mass or less, and the unsaturated carboxylic acid ester-based monomer unit is Containing 0% by mass or more and 30% by mass or less,
The styrene copolymer resin (C) contains 10 mass of the styrene monomer unit when the total content of the styrene monomer unit and the unsaturated carboxylic acid ester monomer unit is 100% by mass. % or more and 90 mass % or less, and the unsaturated carboxylic acid ester monomer unit content is 10 mass % or more and 90 mass % or less. The total light transmittance measured using a 2 mm thick flat plate is 65% or more and less than 90%, and the haze measured using a 1 mm thick flat plate is 5% or more and 70% or less. A styrenic resin composition as described. 3. The styrenic resin composition according to claim 1, wherein said styrenic resin composition has a Vicat softening temperature of 88[deg.] C. or higher. A sheet comprising a layer formed from the styrene resin composition according to any one of claims 1 to 3. 5. The sheet according to claim 4, further comprising a barrier layer having gas barrier properties. A molded article characterized by being formed from the sheet according to claim 4 or 5.