Styrene-based resin composition and molded article using the same

Abstract

The present invention provides a styrene-based resin composition, as well as sheets, films, molded articles, and shrink films, that exhibit excellent impact strength and shrinkage rate in room temperature and low temperature ranges. [Solution] A styrene-based resin composition comprising a matrix phase containing a copolymer (A) having a styrene monomer, a first (meth)acrylic acid ester monomer unit, and a second (meth)acrylic acid ester monomer unit, and rubbery polymer particles in which the styrene monomer, the first (meth)acrylic acid ester monomer unit, and the second (meth)acrylic acid ester monomer unit are graft copolymerized, wherein the copolymer (A) comprises 40 to 60% by mass of the styrene monomer unit, the first (meth)acrylic acid ester monomer unit, and 10 to 30% by mass of the second (meth)acrylic acid ester monomer unit which approximates the Hansen solubility parameter of the styrene monomer unit.

Description

[Technical Field]

[0001] The present invention relates to a styrene-based resin composition and a molded article using the same. [Background technology]

[0002] Styrene resins are lightweight and easy to mold, making them suitable for use in various industrial fields as foams, sheets, or enclosures. However, their low impact strength limits their applications. In particular, when using polystyrene resins for industrial materials, it is crucial to improve impact resistance without reducing rigidity such as elastic modulus. Therefore, high-impact polystyrene (HIPS), a polystyrene resin with improved impact resistance, has a structure in which rubber-like particles are dispersed in a polystyrene resin matrix. As a result, it excels in impact resistance, dimensional stability, and moldability, and is used in a wide range of technological fields.

[0003] On the other hand, shrink labels, which are printed on a heat-shrinkable film (so-called shrink film), are widely attached to beverage containers or food containers, such as PET bottles and other plastic bottles, from the viewpoint of display, decoration, or functionality. For example, Patent Document 1 discloses a technology for a heat-shrinkable label film in which a polyolefin resin layer is used as the core material, and layers mainly composed of polystyrene resin or polyester resin are laminated on both sides of the core material via adhesive layers mainly composed of acid-modified polyethylene resin. Furthermore, Patent Document 2 discloses a technology for a resin composition containing (A) a block copolymer resin composition having predetermined properties obtained by mixing at least two types of vinyl aromatic hydrocarbon-conjugated diene block copolymers, and (B) a copolymer obtained by epoxidizing a styrene-butadiene block copolymer. [Prior art documents] [Patent Documents]

[0004] Patent Document 1 Japanese Patent Application Laid-Open No. 11-262981 Patent Document 2 Japanese Patent Application Laid-Open No. 2013-199616 Summary of the Invention Problems to be Solved by the Invention

[0005] The above Patent Documents 1 and 2 are technologies that utilize the properties of block copolymers such as styrene-butadiene block copolymers and styrene-isoprene block copolymers to improve sealing processability, sealing strength, and adhesiveness to polyester resins. Beverage containers or food containers using these technologies are generally used in a low-temperature range below room temperature (for example, 4°C to -30°C) from the perspective of food preservation of their contents. However, in Patent Documents 1 and 2, no consideration has been given to impact strength and shrinkage in the low-temperature range.

[0006] Therefore, an object of the present disclosure is to provide a styrenic resin composition, as well as a sheet, a film, a molded body, and a shrink film, which exhibit excellent impact strength at room temperature and in a low-temperature range, and a high shrinkage rate during heating. Means for Solving the Problems

[0007] As a result of intensive studies to solve the above problems, the inventor found that a styrenic resin composition containing a matrix phase containing a copolymer (A) containing a styrene monomer unit and two predetermined (meth)acrylate monomer units, and predetermined rubber-like polymer particles exhibits excellent impact strength at room temperature and in a low-temperature range, and a high shrinkage rate during heating, and thus completed the present invention.

[0008] That is, the present invention is as follows. [1] A styrene resin composition comprising a matrix phase containing a copolymer (A) having a styrene monomer unit, a first (meth)acrylic acid ester monomer unit, and a second (meth)acrylic acid ester monomer unit, and rubber-like polymer particles obtained by graft copolymerizing the styrene monomer unit, the first (meth)acrylic acid ester monomer unit, and the second (meth)acrylic acid ester monomer unit, wherein the copolymer (A) has 40 to 60% by mass of the styrene monomer unit, the first (meth)acrylic acid ester monomer unit, and 10 to 30% by mass of the second (meth)acrylic acid ester monomer unit whose Hansen solubility parameter is approximated to that of the styrene monomer unit from the Hansen solubility parameter of the first (meth)acrylic acid ester monomer, the refractive index of the matrix phase at 25°C is in the range of 1.540 to 1.560, and the absolute value of the refractive index difference from the rubber-like polymer is more than 0 and 0.040 or less, the content of the rubber-like polymer particles in the entire styrene resin composition is 20 to 35% by weight, the average particle diameter of the rubber-like polymer particles is 0.80 μm or more and 2.5 μm or less, A styrene resin composition having a Vicat softening temperature of 60 to 75°C.

[0009] [2] The styrene resin composition according to [1], wherein the ratio of the first (meth)acrylic acid ester to the second (meth)acrylic acid ester in the matrix phase (first (meth)acrylic acid ester / second (meth)acrylic acid ester) is 0.1 or more and 5 or less.

[0010] [3] The impact strength by a notched Charpy impact test at 23°C is 15 J / cm , , ,

[0011] ,

[0010] , , , , , 2 ,

[0009] or more. The styrene resin composition according to [1] or [2].

[0011] [4] The styrene resin composition according to any one of [1] to [3], containing the matrix phase as the sea phase and the rubber-like polymer particles as the island phase.

[0012] A sheet containing the styrene-based resin composition described in any of [5][1] to [4].

[0013] A film containing the styrene-based resin composition described in any of [6][1] to [4].

[0014] A molded article obtained by injection molding a styrene-based resin composition as described in any of [7][1] to [4].

[0015] A container formed by molding the sheet described in [8] and [5].

[0016] A shrink film containing the styrene-based resin composition described in any of [9][1] to [4]. [Modes for carrying out the invention]

[0017] The embodiments of the present invention (hereinafter referred to as "these embodiments") will be described in detail below, but the present invention is not limited to the following description and can be implemented in various ways within the scope of its gist.

[0018] [Styrene-based resin composition] The styrene-based resin composition of this embodiment includes a matrix phase comprising a copolymer (A) having styrene-based monomer units, a first (meth)acrylic acid ester monomer unit, and a second (meth)acrylic acid ester monomer unit, and rubbery polymer particles in which the styrene-based monomer unit, the first (meth)acrylic acid ester monomer unit, and the second (meth)acrylic acid ester monomer unit are graft copolymerized. The copolymer (A) comprises 40 to 60% by mass of the styrene monomer units and 10 to 30% by mass of the second (meth)acrylic acid ester monomer units, based on the total amount of copolymer (A). The content of the first (meth)acrylic acid ester monomer units may be 10 to 50% by mass, based on the total amount of copolymer (A). Furthermore, the second (meth)acrylic acid monomer, which is a precursor of the second (meth)acrylic acid monomer unit, approximates the Hansen solubility parameter of the styrene monomer more than the Hansen solubility parameter of the first (meth)acrylic acid monomer. The refractive index of the matrix phase at 25°C is in the range of 1.540 to 1.560, and the absolute value of the refractive index difference (refractive index difference at 25°C) between the rubbery polymer particles and the matrix phase is greater than 0 and less than or equal to 0.040. The content of the rubbery polymer particles relative to the entire styrene-based resin composition is 20 to 35% by weight, and the average particle size of the rubbery polymer particles is 0.80 μm or more and 2.5 μm or less. Furthermore, the Vicat softening temperature of the styrene-based resin composition is 60 to 75°C. This makes it possible to provide a composition with excellent mechanical strength (especially excellent impact strength) and shrinkage rate at room temperature (e.g., in the room temperature range (22-30°C)) and low temperature range (e.g., 4°C to -30°C). The matrix phase and rubbery polymer particles of this embodiment will be described below.

[0019] In other words, the styrene-based resin composition of this embodiment preferably has a so-called matrix-domain structure. That is, the styrene-based resin composition of this embodiment can form a matrix-domain structure by comprising a matrix phase containing a copolymer (A) having styrene-based monomer units, a first (meth)acrylic acid ester monomer unit, and a second (meth)acrylic acid ester monomer unit, and a domain phase which is rubbery polymer particles in which styrene-based monomer units, the first (meth)acrylic acid ester monomer unit, and the second (meth)acrylic acid ester monomer unit are graft copolymerized. Furthermore, the styrene-based resin composition of this embodiment has a sea-island structure in which the matrix phase is a continuous sea phase and the domain phase is an island phase.

[0020] (Matrix phase) The styrene-based resin composition of this embodiment comprises rubbery polymer particles containing a rubbery polymer, and a matrix phase containing a copolymer (A) comprising styrene monomer units and at least two types of (meth)acrylic acid ester monomer units (a first (meth)acrylic acid ester monomer unit and a second (meth)acrylic acid ester monomer unit). The rubbery polymer particles can be dispersed in the matrix phase (so-called continuous phase). Therefore, the matrix phase can be likened to a sea phase and the rubbery polymer particles to islands, and the structure can also be called a sea-island structure. The matrix phase of the styrene-based resin composition of this embodiment comprises a copolymer (A) containing styrene monomer units and at least two types of (meth)acrylic acid ester monomer units (a first (meth)acrylic acid ester monomer unit and a second (meth)acrylic acid ester monomer unit). The proportion of copolymer (A) to the total matrix phase of the styrene-based resin composition is preferably 64 to 100% by mass, more preferably 71 to less than 100% by mass, and more preferably 74 to 81% by mass. The styrene-based resin composition or matrix phase of this embodiment may contain copolymer (A) and optionally any additional components. In this specification, "matrix phase" refers to the continuous phase of the polymer (also called the polymer matrix phase), which is the dominant phase when the polymer component in a styrene-based resin composition has a phase separation structure (preferably a sea-island structure). On the other hand, rubbery polymer particles are the phase present in the matrix phase (so-called dispersed phase), and their form can be (omitted) spherical, cylindrical, or irregularly shaped.

[0021] The monomer units constituting the copolymer (A) of this embodiment preferably contain styrene monomer units, a first (meth)acrylic acid ester monomer unit, and a second (meth)acrylic acid ester monomer unit, and optionally contain vinyl monomer units (i) copolymerizable with styrene monomers. Therefore, copolymer (A) is preferably one or more selected from the group consisting of a styrene copolymer resin (A1) containing styrene monomer units and at least two types of (meth)acrylic acid ester monomer units, or a styrene copolymer resin (A2) containing styrene monomer units, at least two types of (meth)acrylic acid ester monomer units, and vinyl monomer units (i). As described later, an example of copolymer (A) is a styrene-(meth)acrylic acid ester copolymer. Furthermore, the copolymer (A) in this embodiment is preferably a random copolymer or an alternating copolymer, and a random copolymer is more preferred. In this specification, "styrene monomer unit" refers to a repeating unit that constitutes a polymer formed by the polymerization of styrene monomers. It is a repeating unit (or structural unit) in which the carbon-carbon double bond in the styrene monomer has been replaced by a single bond (-CC-) through polymerization or crosslinking reactions. Therefore, styrene monomers can also be precursors to styrene monomer units. The same applies to other monomer units in this specification.

[0022] In this embodiment, the weight-average molecular weight (Mw) of the matrix phase is preferably 100,000 to 300,000, more preferably 150,000 to 300,000, even more preferably 150,000 to 270,000, and even more preferably 150,000 to 240,000. If the weight-average molecular weight is less than 100,000, the impact strength of the styrene-based resin composition may decrease, and if the weight-average molecular weight exceeds 300,000, the fluidity of the styrene-based resin composition may decrease, impairing productivity. Furthermore, the method for measuring the weight-average molecular weight in this invention is as described in the "Examples" section.

[0023] The refractive index of the matrix phase in this embodiment at 25°C is 1.540 to 1.560, preferably 1.541 to 1.559, more preferably 1.542 to 1.558, and even more preferably 1.543 to 1.557. A refractive index of the matrix phase in the range of 1.541 to 1.559 is preferable from the viewpoint of material selection because it can be selected from commercially available rubbery polymers. In order to set the refractive index of the matrix phase within the above range, conditions are required to adjust the composition of the styrene monomer, the first (meth)acrylic acid ester monomer, and the second (meth)acrylic acid ester monomer.

[0024] In this embodiment, the absolute value of the difference in refractive index between the matrix phase and the rubbery polymer particles is preferably greater than 0 and less than or equal to 0.040, and within the range of greater than 0 and less than or equal to 0.015. For example, the lower limit of the absolute value of the difference in refractive index is 0.005. When considering the balance between appropriate visibility and excellent low-temperature impact strength of the styrene-based resin composition of this embodiment, the absolute value of the difference in refractive index between the matrix phase and the rubbery polymer particles is preferably in the range of 0.004 to 0.01, more preferably in the range of 0.005 to 0.01, and even more preferably in the range of 0.006 to 0.01. When the absolute value of the difference in refractive index between the matrix phase and the rubbery polymer particles is within the above range, appropriate visibility and excellent fluidity can be ensured. In this embodiment, in order to make the absolute value of the difference in refractive index between the matrix phase and the rubbery polymer particles within the above range, it is necessary to adjust the refractive index of the matrix phase according to the refractive index of the rubber component used in the rubbery polymer. The method for measuring refractive index described herein is the method described in the Examples section below. In this embodiment, the matrix phase preferably contains a random copolymer (A) and optional additives as needed. In this embodiment, the total content of the random copolymer (A) and optional additives is preferably 64 to 100% by mass, more preferably 71 to 100% by mass, and more preferably 74 to 81% by mass, relative to the entire matrix phase (100% by mass).

[0025] The upper limit of the matrix phase content in the styrene-based resin composition of this embodiment is preferably 80% by mass or less, 74% by mass or less, 70% by mass or less, 65% by mass or less, 63% by mass or less, and 60% by mass or less, based on 100% by mass of the total amount of the styrene-based resin composition. On the other hand, the lower limit of the matrix phase content in the styrene-based resin composition is preferably 50% by mass or more, 53% by mass or more, 55% by mass or more, 57% by mass or more, and 59% by mass or more, based on 100% by mass of the total amount of the styrene-based resin composition. These upper and lower limits can be combined arbitrarily.

[0026] <Styrene-based monomers> The copolymer (A) of this embodiment essentially contains styrene monomer units. The content of styrene monomer units among the monomer units constituting copolymer (A) of this embodiment is preferably 37 to 66% by mass, more preferably 39 to 63% by mass, even more preferably 41 to 61% by mass, even more preferably 46 to 56% by mass, and even more preferably 49 to 54% by mass, relative to the total amount of copolymer (A). The content of styrene monomer units, (meth)acrylic acid ester monomer units, and vinyl monomer units (i) in copolymer (A) is determined by proton nuclear magnetic resonance ( 1 It can be determined from the integral ratio of the spectrum measured by 1H-NMR measurement.

[0027] In this embodiment, the styrene monomer is preferably monovinyl in structure, and examples include styrene, α-methylstyrene, α-methylp-methylstyrene, ο-methylstyrene, m-methylstyrene, p-methylstyrene, vinyltoluene, ethylstyrene, isobutylstyrene, t-butylstyrene, bromostyrene, and styrene derivatives such as indene. Styrene is particularly preferred as the styrene monomer. One or more of these styrene monomers can be used.

[0028] In this embodiment, the Hansen solubility parameter of the styrene monomer is 18.5 to 19.5 (MPa).1 / 2 ) is preferable. The general solubility parameter (SP value) is calculated using the function of the cohesive energy density shown in the following formula. SP value ((cal / cm 3 )) 1 / 2 ) = (△E / V) 1 / 2 Formula (1) (△E represents the intermolecular cohesive energy (heat of vaporization), V represents the total volume of the mixed solution, and △E / V represents the cohesive energy density.) In addition, the heat quantity change △Hm due to mixing is represented by the following formula using the SP value. △Hm = V(δ1 - δ2)·Φ1·Φ2 ··· Formula (2) (δ1 represents the SP value of the solvent, δ2 represents the SP value of the solute, Φ1 represents the volume fraction of the solvent, and Φ2 represents the volume fraction of the solute.) From the above formulas (1) and (2), the closer the values of δ1 and δ2 are, the smaller △Hm becomes, and the smaller the Gibbs free energy becomes. Therefore, those with a small difference in SP values have a high affinity for each other. As a method for obtaining the SP value in this specification, the Hansen solubility parameter is used. The Hansen solubility parameter is a parameter developed by Charles M. Hansen as a method for predicting whether a certain substance dissolves in another substance to form a solution. Specifically, the Hansen solubility parameter is referred to as HSP, and each molecule is given the following three parameter terms (δ D , δ P , δ H ), and is calculated from the following formula. Each unit is (MPa) 1 / 2 .

Equation

[0029] <First (meth)acrylic acid ester monomer> The copolymer (A) of this embodiment contains at least two types of (meth)acrylic acid ester monomer units. Among the monomers that are precursors of the at least two types of (meth)acrylic acid ester monomer units, the (meth)acrylic acid ester monomer having a Hansen solubility parameter value that is closest to the Hansen solubility parameter value of the styrene monomer that is a precursor of the styrene monomer unit in copolymer (A) is designated as the second (meth)acrylic acid ester monomer. On the other hand, among the monomers that are precursors of the at least two types of (meth)acrylic acid ester monomer units, the (meth)acrylic acid ester monomer having a Hansen solubility parameter value that is furthest from the Hansen solubility parameter value of the styrene monomer that is a precursor of the styrene monomer unit in copolymer (A) is designated as the first (meth)acrylic acid ester monomer. Because the copolymer (A) constituting the matrix phase has a first (meth)acrylic acid ester monomer unit and a second (meth)acrylic acid ester monomer unit, the flexibility of the polymer chain of the entire copolymer (A) can be highly controlled, which is thought to result in a relatively low Vicat softening temperature and excellent mechanical properties at low temperatures.

[0030] The copolymer (A) of this embodiment essentially contains a first (meth)acrylic acid ester monomer unit. The lower limit of the content of the first (meth)acrylic acid ester monomer unit among the monomer units constituting the copolymer (A) of this embodiment includes 10% by mass or more, 10.5% by mass or more, 11% by mass or more, 11.5% by mass or more, 12% by mass or more, 12.5% ​​by mass or more, 13% by mass or more, 14% by mass or more, 15% by mass or more, 16% by mass or more, 17% by mass or more, 18% by mass or more, 19% by mass or more, 20% by mass or more, 21% by mass or more, 22% by mass or more, and 23% by mass or more. On the other hand, the upper limits for the content of the first (meth)acrylic acid ester monomer unit include 35% by mass or less, 33.5% by mass or less, 31% by mass or less, 30% by mass or less, 29% by mass or less, 28.5% by mass or less, 28% by mass or less, 27% by mass or less, 26% by mass or less, or 25% by mass or less. The above upper and lower limits can be combined in any way. Furthermore, the preferred range for the content of the first (meth)acrylic acid ester monomer unit is, for example, 10% to 35% by mass, more preferably 15 to 35% by mass, even more preferably 17 to 33% by mass, even more preferably 19 to 31% by mass, even more preferably 21 to 29% by mass, and particularly preferably 23 to 27% by mass, relative to the total amount of copolymer (A). A content of 10 to 35% by mass of the first (meth)acrylic acid ester monomer unit in copolymer (A) is preferable from the viewpoint of balancing moderate shrinkage characteristics and excellent low-temperature impact strength. Furthermore, it has been confirmed that the ratio of the mass percentage of the second (meth)acrylic acid ester monomer unit to the mass percentage of the first (meth)acrylic acid ester monomer unit in copolymer (A) (= (mass percentage of the second (meth)acrylic acid ester monomer unit) / (mass percentage of the first (meth)acrylic acid ester monomer unit)) affects excellent impact strength at room temperature and low temperature ranges, or high shrinkage rate when heated. Therefore, by setting the content of the first (meth)acrylic acid ester monomer unit in copolymer (A) to the range of 10 to 35% by mass, it becomes easier to adjust the above ratio within a predetermined range.

[0031] In this embodiment, the Hansen solubility parameter of the first (meth)acrylic acid monomer is 16.5 to 17.5 (MPa). 1 / 2 ) is preferable. In this embodiment, the difference (absolute value) between the Hansen solubility parameter of the first (meth)acrylic acid monomer and the Hansen solubility parameter of the styrene monomer is 1.4 to 3.1 (MPa). 1 / 2 Preferably, it is 1.6 to 2.8 (MPa) 1 / 2 ) 1 / 2 ), more preferably 1.7 to 2.6 (MPa) 1 / 2 ), more preferably 1.9~2.2(MPa) 1 / 2 )

[0032] The first (meth)acrylic acid ester monomer of this embodiment is the following general formula (1): [ka] (In the above general formula (1), R 1 R represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. 2 represents an ester substituent, specifically an alkyl group having 2 to 12 carbon atoms. It is preferable that it be represented as ). In this embodiment, the ester substituent of the first (meth)acrylic acid monomer (R in the above general formula (1)) 2 The number of carbon atoms in the ester substituent is preferably 1 to 10, more preferably 2 to 8, and even more preferably 3 to 6. If the number of carbon atoms in the ester substituent exceeds 10, the effect of reducing heat resistance is significant and undesirable. Number of carbon atoms in the side chain (=R 2 By selecting monomers whose molecular weight falls within the above range, an appropriate free volume is ensured in the molecular chains of copolymer (A), thereby imparting flexibility. This is thought to enable the development of excellent impact resistance, particularly in low-temperature environments, while maintaining rigidity with the second (meth)acrylic acid ester monomer.

[0033] Examples of the first (meth)acrylate monomer in this embodiment include propyl (meth)acrylate, butyl (meth)acrylate, cyclohexyl (meth)acrylate, n-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and decyl (meth)acrylate. These can be used in mixtures. Among the unsaturated carboxylic acid monomers, butyl (meth)acrylate is particularly preferred due to its ease of industrial availability.

[0034] <Second (meth)acrylic acid monomer> The copolymer (A) of this embodiment contains at least two types of (meth)acrylic acid ester monomer units. Among the monomers that are precursors of the at least two types of (meth)acrylic acid ester monomer units, the (meth)acrylic acid ester monomer having the Hansen solubility parameter value that is most similar to the value of the styrene monomer that is a precursor of the styrene monomer unit in copolymer (A) is designated as the second (meth)acrylic acid ester monomer.

[0035] The copolymer (A) of this embodiment essentially contains a second (meth)acrylic acid ester monomer unit. The lower limit of the content of the second (meth)acrylic acid ester monomer unit among the monomer units constituting the copolymer (A) of this embodiment includes 15% by mass or more, 15.5% by mass or more, 16% by mass or more, 17% by mass or more, 18% by mass or more, 19% by mass or more, 20% by mass or more, 21% by mass or more, 22% by mass or more, 23% by mass or more, 24% by mass or more, 25% by mass or more, 26% by mass or more, 27% by mass or more, 28% by mass or more, 29% by mass or more, 30% by mass or more, 31% by mass or more, 32% by mass or more, or 33% by mass. On the other hand, the upper limits for the content of the second (meth)acrylic acid ester monomer unit include 46% by mass or less, 44% by mass or less, 43% by mass or less, 42% by mass or less, 41% by mass or less, 40% by mass or less, 39% by mass or less, 38% by mass or less, 37% by mass or less, 36% by mass or less, or 35% by mass or less. The above upper and lower limits can be combined in any way. Furthermore, a preferred range for the content of the second (meth)acrylic acid ester monomer unit is, for example, preferably 15% by mass or more and 46% by mass or less of the total copolymer (A), preferably 25 to 45% by mass of the total copolymer (A), more preferably 27 to 43% by mass, even more preferably 29 to 41% by mass, even more preferably 31 to 39% by mass, and even more preferably 33 to 37% by mass. It is preferable, from the viewpoint of moderate visibility and excellent moldability, that the content of the second (meth)acrylic acid ester monomer unit in copolymer (A) is 15% by mass or more and 46% by mass or less. Furthermore, it was confirmed that the ratio of the mass % of the second (meth)acrylic acid ester monomer unit to the mass % of the first (meth)acrylic acid ester monomer unit in copolymer (A) (= (mass %) of the second (meth)acrylic acid ester monomer unit / (mass %) of the first (meth)acrylic acid ester monomer unit) affects the excellent impact strength at room temperature and low temperature ranges, or the high shrinkage rate when heated. Therefore, by setting the content of the second (meth)acrylic acid ester monomer unit in copolymer (A) to the range of 15 to 46 mass %, it becomes easier to adjust the above ratio to a predetermined range.

[0036] In this embodiment, the Hansen solubility parameter of the second (meth)acrylic acid monomer is 17.0 to 18.0 (MPa). 1 / 2 ) is preferable. In this embodiment, the difference (absolute value) between the Hansen solubility parameter of the second (meth)acrylic acid monomer and the Hansen solubility parameter of the styrene monomer is 0.9 to 2.6 (MPa). 1 / 2 Preferably, the pressure is 1.1 to 2.3 (MPa). 1 / 2 ) 1 / 2 ), more preferably 1.2 to 2.1 (MPa) 1 / 2 ), more preferably 1.4 to 1.7 (MPa) 1 / 2 )

[0037] The second (meth)acrylic acid ester monomer of this embodiment is the following general formula (2): [ka] (In the above general formula (2), R 3 R represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. 4 represents an ester substituent, specifically an alkyl group having 1 to 9 carbon atoms. It is preferable that it be represented as ). In this embodiment, the ester substituent of the second (meth)acrylic acid monomer (R in the above general formula (2)) 4 The number of carbon atoms in the ester substituent is preferably 7 or less, more preferably 5 or less, and even more preferably 3 or less, or 1 or more. If the number of carbon atoms in the ester substituent exceeds 10, the effect of reducing heat resistance is significant and undesirable. Furthermore, in this embodiment, the ester substituent of the second (meth)acrylic acid ester monomer represented by general formula (2) (R in the above general formula (2)) 4 The number of carbon atoms in ) and R 3 The sum of the number of carbon atoms is preferably an integer between 1 and 4, and more preferably an integer between 1 and 3. Monomers with short side chain carbon lengths (=R 4 By selecting a monomer with a small number of carbon atoms (for example, 1 to 3 carbon atoms), copolymerization with styrene monomers is improved, and the compositional distribution in the matrix phase becomes more uniform. This is thought to optimize the balance between the overall mechanical strength and transparency of the resin without hindering the flexibility-granting effect of the first (meth)acrylic acid ester monomer.

[0038] Examples of the second (meth)acrylate monomer in this embodiment include methyl (meth)acrylate, ethyl (meth)acrylate, and propyl (meth)acrylate. These can be used in mixtures. Methyl (meth)acrylate is particularly preferred as the unsaturated carboxylic acid monomer due to its readily available industrially. In a preferred embodiment of copolymer (A) of this embodiment, the ratio of mass% of the second (meth)acrylic acid ester monomer unit to the mass% of the first (meth)acrylic acid ester monomer unit in copolymer (A) (= (mass% of the second (meth)acrylic acid ester monomer unit) / (mass% of the first (meth)acrylic acid ester monomer unit) may be in the range of 1.1 to 2.5, more preferably 1.2 to 2.3, even more preferably 1.1 to 2.2, and even more preferably 1.0 to 2.0. This results in superior impact strength at room temperature and low temperature ranges, or a higher shrinkage rate when heated.

[0039] <Vinyl monomer (i)> The copolymer (A) of this embodiment optionally contains vinyl monomer units (i). In this embodiment, the vinyl monomer (i) is not particularly limited, but examples include (meth)acrylic acid, maleic anhydride, maleic acid, fumaric acid, itaconic acid, cinnamic acid, fumarate esters (e.g., dimethyl fumarate, diethyl fumarate, ethyl fumarate), maleate esters (e.g., dimethyl maleate), (meth)acrylonitrile, maleimide, and nuclear-substituted maleimide. In this specification, the term "(meth)acrylic acid" includes both acrylic acid and methacrylic acid. Similarly, the term "(meth)acrylic acid ester" includes both acrylic acid esters and methacrylic acid esters.

[0040] In this embodiment, the content of vinyl monomer units (i) among the monomer units constituting copolymer (A) is preferably 0 to 10% by mass, more preferably 0 to 7% by mass, even more preferably 0 to 4% by mass, even more preferably 0 to 2% by mass, and even more preferably 0 to 0.5% by mass, relative to the total amount of copolymer (A).

[0041] --Preferred copolymer (A)-- In this embodiment, copolymer (A) comprises 40 to 60% by mass of styrene monomer units, a first (meth)acrylic acid ester monomer unit, and 10 to 30% by mass of a second (meth)acrylic acid ester monomer unit whose Hansen solubility parameter approximates that of the styrene monomer to that of the first (meth)acrylic acid ester monomer. Copolymer (A) may also contain vinyl monomer units (i). In this embodiment, when the total content of styrene monomer units, first (meth)acrylic acid ester monomer units, and second (meth)acrylic acid ester monomer units in copolymer (A) is taken as 100% by mass, the content of styrene monomer units is preferably 44 to 58% by mass, more preferably 46 to 56% by mass, more preferably 48 to 54% by mass, and even more preferably 50 to 53% by mass. By setting the content to 44% by mass or more, the refractive index of copolymer (A) can be improved. On the other hand, by setting the content to 58% by mass or less, it becomes difficult to have the first (meth)acrylic acid ester monomer units and second (meth)acrylic acid ester monomer units in desired amounts. Furthermore, in this embodiment, when the total content of styrene monomer units, first (meth)acrylic acid ester monomer units and second (meth)acrylic acid ester monomer units in copolymer (A) is taken as 100% by mass, the content of first (meth)acrylic acid ester monomer units is preferably in the range of 10 to 26% by mass, more preferably 12 to 25% by mass, more preferably 14 to 24% by mass, and even more preferably 16 to 22% by mass. In this embodiment, the content of styrene monomer units (e.g., styrene monomer units), first (meth)acrylic acid ester monomer units (e.g., butyl acrylate monomer units), and second (meth)acrylic acid ester monomer units (e.g., methyl methacrylate monomer units) in copolymer (A) is determined by proton nuclear magnetic resonance ( 1 It can be determined from the integral ratio of the spectrum measured with a 1H-NMR detector.

[0042] Preferred copolymers (A) in this embodiment include styrene-(meth)acrylate-methyl(meth)acrylate copolymer, styrene-(meth)acrylate-ethyl(meth)acrylate copolymer, and styrene-(meth)acrylate-propyl(meth)acrylate copolymer. More preferably, terpolymers such as styrene-methyl(meth)acrylate-n-butyl(meth)acrylate copolymer, styrene-methyl(meth)acrylate-s-butyl(meth)acrylate copolymer, styrene-methyl(meth)acrylate-t-butyl(meth)acrylate copolymer, or styrene-methyl(meth)acrylate-isobutyl(meth)acrylate copolymer are preferred, and even more preferably, styrene-methyl(meth)acrylate-butyl(meth)acrylate terpolymer or styrene-methyl(meth)acrylate-butyl(meth)acrylate terpolymer.

[0043] In this embodiment, the weight-average molecular weight (Mw) of copolymer (A) is preferably 100,000 to 400,000, more preferably 120,000 to 390,000, and even more preferably 140,000 to 380,000. When the weight-average molecular weight (Mw) is 100,000 to 400,000, a resin with a better balance of mechanical strength and fluidity is obtained, and the inclusion of gel material is also reduced. The weight-average molecular weight (Mw) is a value obtained using gel permeation chromatography on a standard polyethylene basis.

[0044] In this embodiment, it is preferable that the copolymer (A) or the styrene-based resin composition of this embodiment does not substantially contain vinyl cyanide monomers such as acronitrile monomer units or methacrylonitrile monomer units. Specifically, it is preferable that vinyl cyanide monomers are contained in 10% by mass or less, more preferably 5% by mass or less, and even more preferably 2% by mass or less, relative to the total amount of copolymer (A) or matrix phase.

[0045] The copolymer (A) content of this embodiment is preferably 68 to 87% by mass, more preferably 70 to 85% by mass, even more preferably 72 to 83% by mass, and even more preferably 74 to 81% by mass, based on the total mass (100% by mass) of the styrene-based resin composition.

[0046] (Rubber-like polymer particles) In the styrene-based resin composition of this embodiment, the rubbery polymer particles may be included in the styrene-based resin composition as part of a rubber-modified styrene-based resin (for example, HIPS or transparent HIPS), or rubbery polymer particles other than those included in the rubber-modified styrene-based resin may be further blended with the matrix phase or copolymer (A) and included in the styrene-based resin composition. The rubbery polymer particles of this embodiment may, for example, contain copolymer (A) and / or polystyrene internally, and / or have copolymer (A) and / or polystyrene grafted onto the outside. Furthermore, the rubbery polymer particles of this embodiment include not only a core-shell structure composed of copolymer (A) as a core and a rubbery polymer as a shell enclosing the core, but also a salami structure composed of multiple copolymer (A) as cores and a rubbery polymer as a shell enclosing the multiple copolymer (A) as cores.

[0047] As the material for the rubbery polymer or rubbery polymer particles in this embodiment, for example, polybutadiene, polystyrene-encapsulated polybutadiene, polyisoprene, natural rubber, polychloroprene, styrene-butadiene copolymer, acrylonitrile-butadiene copolymer, etc. can be used, but polybutadiene or styrene-butadiene copolymer is preferred. For polybutadiene, both high-cis polybutadiene with a high cis content and low-cis polybutadiene with a low cis content can be used. Furthermore, both random structures and block structures can be used for the styrene-butadiene copolymer. One or more of these rubbery polymers can be used. Also, saturated rubber obtained by hydrogenating butadiene-based rubber can be used. Examples of such rubber-modified styrene resins include HIPS (high-impact polystyrene), ABS resin (acrylonitrile-butadiene-styrene copolymer), and AES (acrylonitrile-ethylene propylene rubber-styrene copolymer).

[0048] In this embodiment, the content of the rubbery polymer contained in the styrene-based resin composition (this refers to the content of the rubbery polymer itself (e.g., a conjugated diene polymer such as polybutadiene), and does not include the polymer encapsulated within the rubbery polymer particles (copolymer (A) and / or polystyrene inside)) is more preferably 1.0 to 15% by mass, more preferably 1.2 to 12% by mass, even more preferably 1.5 to 10% by mass, even more preferably 2.0 to 10% by mass, and still more preferably 3 to 9% by mass, based on the total amount (100% by mass) of the styrene-based resin composition. If the content of the rubbery polymer is less than 1.0% by mass, there is a concern that the impact resistance of the entire styrene-based resin composition will decrease. Furthermore, if the content of the rubbery polymer exceeds 15% by mass, there is a concern that the fluidity of the entire styrene-based resin composition will decrease. In this disclosure, the content of the rubbery polymer contained in the styrene-based resin composition is the value calculated using the method described in the Examples section.

[0049] In this embodiment, the content of rubbery polymer particles contained in the styrene-based resin composition (including the content of the rubbery polymer itself (e.g., a conjugated diene polymer such as polybutadiene, or styrene-butadiene rubber) and the content of the polymer (copolymer (A) and / or polystyrene) encapsulated within the rubbery polymer particles) is preferably 3 to 36% by mass, more preferably 9 to 33% by mass, even more preferably 15 to 30% by mass, even more preferably 17 to 27% by mass, even more preferably 20 to 25% by mass, even more preferably 21 to 25% by mass, and particularly preferably 22.8 to 25% by mass, based on the total mass of the styrene-based resin composition (100% by mass). In this disclosure, the content of rubbery polymer particles in the styrene-based resin composition is the value calculated using the method described in the Examples section.

[0050] In this embodiment, the average particle size of the rubbery polymer particles contained in the styrene-based resin composition is 0.80 μm or more and 2.5 μm or less, preferably more than 0.8 μm and 2.5 μm or less, more preferably 0.9 μm or more and 2.4 μm, and from the viewpoint of achieving both transparency and impact resistance, preferably more than 0.9 μm and 2.3 μm, and more preferably 0.92 μm and 2.2 μm. When considering the balance between low-temperature impact strength and fluidity, in this embodiment, the lower limit of the average particle size of the rubbery polymer particles contained in the styrene-based resin composition is preferably 0.8 μm, more preferably more than 0.9 μm, more preferably 1.0 μm, and more preferably 1.1 μm. Furthermore, the upper limit of the average particle size of the rubbery polymer particles is preferably 2.4 μm, more preferably 2.3 μm, more preferably 2.2 μm, more preferably 2.1 μm, and more preferably 1.95 μm. Furthermore, the preferred range for the average particle diameter of the rubbery polymer particles may be a range obtained by arbitrarily combining the upper limit and lower limit of the average particle diameter. In this disclosure, the average particle size of the rubbery polymer particles contained in the styrene-based resin composition is the value calculated by the method described in the Examples section.

[0051] In this embodiment, when the styrene-based resin composition is a rubber-modified styrene-based resin (HIPS-based resin), among these rubbery polymers, polybutadiene and styrene-butadiene rubber are particularly preferred, with styrene-butadiene rubber being the most preferred.

[0052] (Additives) In this embodiment, various additives may be included as needed, within the limits that do not impair the objectives of the present invention, at any stage before or after the recovery process when manufacturing each component of the styrene resin composition, or at the stage of extruding or molding the styrene resin composition. Examples of the aforementioned additives include antioxidants, ultraviolet absorbers, light stabilizers, lubricants, antistatic agents, flame retardants, higher fatty acid compounds, plasticizers, various dyes and pigments, inorganic nucleating agents (metal oxides such as titanium dioxide and tin oxide), organic nucleating agents, fluorescent whitening agents, light diffusing agents, and selective wavelength absorbers. Furthermore, the above-mentioned additive in the styrene-based resin composition is preferably 0% to 6.0% by mass, more preferably 0% to 3.5% by mass, even more preferably 0% to 0.9% by mass, and even more preferably 0% to 0.5% by mass, based on 100% by mass of the styrene-based resin composition.

[0053] <Higher fatty acid compounds> Examples of higher fatty acid compounds in this embodiment include esters of higher fatty acids and higher alcohols (e.g., myristyl myristate, stearyl stearate, octyldodecyl behenate, behenyl behenate), esters of higher fatty acids and sorbitan (sorbitan monopalmitate, sorbitan monostearate, sorbitan tristearate, sorbitan distearate, sorbitan monobehenate), esters of higher fatty acids and glycerin (glycerin monostearate, glycerin distearate, glycerin tristearate, glyceryl myristate, glyceryl palmitate, glyceryl behenate, glyceryl oleate), or hydrogenated oils (highly hydrogenated beef tallow, hydrogenated castor oil). The higher fatty acid compounds may be used alone or in combination of two or more. In the styrene-based resin composition of this embodiment, the content of the higher fatty acid compound is preferably 0 to 0.7% by mass, more preferably 0.03 to 0.7% by mass, even more preferably 0.05 to 0.65% by mass, even more preferably 0.07 to 0.6% by mass, and still more preferably 0.1 to 0.55% by mass, based on the total amount (100% by mass) of the styrene-based resin composition.

[0054] <Plasticizer> The styrene-based resin composition of this embodiment may optionally contain known plasticizers other than higher fatty acid compounds. Specific examples of such plasticizers include, from the viewpoint of thermal stability, liquid paraffin or aliphatic or cyclic hydrocarbons (e.g., nonane, decane, decalin, p-xylene, undecane, or dodecane), and silicone oil. Among these, liquid paraffin is more preferred as the plasticizer in this embodiment. In the styrene-based resin composition of this embodiment, the plasticizer content is preferably 0.05% by mass or more and 5% by mass or less, more preferably 0.1% by mass or more and 2.8% by mass or less, even more preferably 0.15% by mass or more and 2% by mass or less, and even more preferably 0.2% by mass or more and 1.8% by mass or less, based on 100% by mass of the total amount of the styrene-based resin composition.

[0055] The above-mentioned liquid paraffin, also called mineral oil, is an oligomer and polymer containing paraffinic hydrocarbons. The above-mentioned liquid paraffin contains paraffinic oil, naphthenic oil, and paraffin wax, and is a mixture of paraffinic hydrocarbons and alkylnaphthenic hydrocarbons. This includes both those with a specific gravity of 0.8494 or less at 15°C and those with a specific gravity of more than 0.8494 at 15°C. Furthermore, the naphthene content of the above-mentioned liquid paraffin is preferably 15% to 55% by mass, more preferably 20% to 45% by mass, and even more preferably 19% to 35% by mass, based on 100% by mass of the liquid paraffin. In this embodiment, the kinematic viscosity (40°C) of the liquid paraffin can be appropriately set according to the intended use, but is preferably 3 to 500 mm² / s, more preferably 5 to 400 mm² / s, even more preferably 6 to 300 mm² / s, and particularly preferably 7 to 150 mm² / s. Furthermore, the kinematic viscosity of the above-mentioned liquid paraffin was measured in accordance with JIS K2283. Specifically, the measurement temperature was 40°C, and an automatic viscosity measuring device (VMC-252 model) (manufactured by Rigosha Co., Ltd.) using an Ubbelohde viscometer (viscometer number 2) was employed. For example, while there are no particular restrictions on typical liquid paraffins, preferred options include: Cristoll® N352 and Primol® N382 from ExxonMobil Limited; PL-380 from Sonneborn; Diana Process Oil® PW-380, PW-150, PW-100, PW-90, and Daphne Oil® CP68N and CP50S from Idemitsu Kosan Co., Ltd.; Liquid Paraffin 350-S, PS-350S, and LP530-SP from Sanko Chemical Industries; F380N from Formosa; PARACOS KF-550 and PARACOS KF-350 from Seojin Chemical; and Edelex 226 from Shell Chemicals Japan.

[0056] <Antioxidant> The styrene-based resin composition of this embodiment may contain an antioxidant. In the styrene-based resin composition of this embodiment, the antioxidant content is preferably 0.001 to 0.5% by mass, more preferably 0.01 to 0.45% by mass, even more preferably 0.03 to 0.4% by mass, and still more preferably 0.05 to 0.35% by mass, based on 100% by mass of the total amount of the styrene-based resin composition. Examples of the above-mentioned antioxidants include phenolic compounds, phosphorus compounds, and thioether compounds. Examples of the above-mentioned phenolic antioxidants include 2,6-di-tert-butyl-p-cresol, 2,6-diphenyl-4-octadecyloxyphenol, distearyl(3,5-di-tert-butyl-4-hydroxybenzyl)phosphonate, 1,6-hexamethylenebis[(3,5-di-tert-butyl-4-hydroxyphenyl)propionamide], 4,4'-thiobis(6-tert-butyl-m-cresol), 2,2'-methylenebis(4-methyl-6-tert-butylphenol), and 2,2'-methylene Bis(4-ethyl-6-tert-butylphenol), 4,4'-butylidenebis(6-tert-butyl-m-cresol), 2,2'-ethylidenebis(4,6-di-tert-butylphenol), 2,2'-ethylidenebis(4-sec-butyl-6-tert-butylphenol), 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane, 1,3,5-tris(2,6-dimethyl-3-hydroxy-4-tert-butylbenzyl)isocyanurate, 1,3,5-tris(3 ,5-di-tert-butyl-4-hydroxybenzyl)isocyanurate, 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)-2,4,6-trimethylbenzene, 2-tert-butyl-4-methyl-6-(2-acryloyloxy-3-tert-butyl-5-methylbenzyl)phenol, stearyl [3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate methyl ]methane, thiodiethylene glycol bis[(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 1,6-hexamethylene bis[(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], bis[3,3-bis(4-hydroxy-3-tert-butylphenyl)butyric acid] glycol ester, bis[2-tert-butyl-4-methyl-6-(2-hydroxy-3-tert-butyl-5-methylbenzyl)phenyl] terephthalate, 1,3,5-tris[(3,Examples include 5-di-tert-butyl-4-hydroxyphenyl)propionyloxyethyl]isocyanurate, 3,9-bis[1,1-dimethyl-2-{(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy}ethyl]-2,4,8,10-tetraoxaspiro[5,5]undecane, and triethylene glycol bis[(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate]. These may be used individually or in combination of two or more.

[0057] Examples of the phosphorus-based antioxidants mentioned above include tris(2,4-di-tert-butylphenyl) phosphite, trisnonylphenyl phosphite, tris[2-tert-butyl-4-(3-tert-butyl-4-hydroxy-5-methylphenylthio)-5-methylphenyl] phosphite, tridecyl phosphite, octyldiphenyl phosphite, di(decyl)monophenyl phosphite, di(tridecyl)pentaerythritol diphosphite, and di(nonylphenyl)pentaerythritol. Tall diphosphite, bis(2,4-tert-butylphenyl)pentaerythritol diphosphite, bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphite, bis(2,4,6-tri-tert-butylphenyl)pentaerythritol diphosphite, bis(2,4-dicumylphenyl)pentaerythritol diphosphite, tetra(tridecyl)isopropylidene diphenol diphosphite, tetra(tridecyl)-4,4'-n-butyl Redenbis(2-tert-butyl-5-methylphenol) diphosphite, hexa(tridecyl)-1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane triphosphite, tetrakis(2,4-di-tert-butylphenyl) biphenylenediphosphonite, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 2,2'-methylenebis(4,6-di-tert-butylphenyl)-2-ethylhexylphosphite Examples include 2,2'-methylenebis(4,6-di-tert-butylphenyl)-octadecyl phosphite, 2,2'-ethylidenebis(4,6-di-tert-butylphenyl)fluorophosphite, tris(2-[(2,4,8,10-tetrakis-tert-butyldibenzo[d,f][1,3,2]dioxaphosphine-6-yl)oxy]ethyl)amine, and phosphites of 2-ethyl-2-butylpropylene glycol and 2,4,6-tri-tert-butylphenol. These may be used individually or in combination of two or more.

[0058] Examples of the thioether-based antioxidants mentioned above include dialkylthiodipropionates such as dilauryl thiodipropionate, dimyristyl thiodipropionate, and distearyl thiodipropionate, as well as pentaerythritol tetra(β-alkylmercapto)propionate esters. These may be used individually or in combination of two or more.

[0059] The styrene-based resin composition of this embodiment contains rubbery polymer particles and copolymer (A), and the total content of rubbery polymer particles and copolymer (A) is preferably 70 to 100% by mass, and more preferably 80 to 98.5% by mass, relative to the entire styrene-based resin composition. The styrene-based resin composition of this embodiment comprises rubbery polymer particles, copolymer (A), and additives, and the total content of rubbery polymer particles, styrene-based polymer, and higher fatty acid compound is preferably 70 to 100% by mass, and more preferably 80 to 98.5% by mass, relative to the entire styrene-based resin composition.

[0060] [Physical properties of styrene-based resin compositions] <Meltmass Flowrate> In this embodiment, the total melt mass flow rate (MFR) of the styrene-based resin composition is 1.5 to 5 g / 10 min, preferably 1.8 to 4.5 g / 10 min, and more preferably 2 to 4 g / 10 min. The melt mass flow rate of the styrene-based polymer or polymer matrix phase is the value measured at 200°C and 49N according to JIS K 7210-1. If the total melt mass flow rate (MFR) of the styrene-based resin composition is less than 1.5 g / 10 min, productivity will be poor due to insufficient fluidity. On the other hand, if the melt mass flow rate (MFR) exceeds 7 g / 10 min, the fluidity will be too high, resulting in poor container moldability.

[0061] <Total light transmittance> The styrene-based resin composition of this embodiment was injection-molded into a 2 mm plate to produce a 2 mm thick test specimen. The total light transmittance of the test specimen was then measured using the conditions specified in JIS K 7361-1. The total light transmittance of the test specimen was preferably 89% or higher, more preferably 90% or higher, and even more preferably 91% or higher. <Hayes> In this embodiment, after preparing a 2 mm thick test piece using the styrene-based resin composition of this embodiment as a molding material, the haze value measured on the test piece in accordance with JIS K 7105 is preferably 30% or less, more preferably 27% or less, and even more preferably 24% or less. When the haze value falls within the above range, a certain level of transparency can be ensured, providing the advantage of allowing the contents of the container to be visually inspected. In this embodiment, in order to eliminate external factors caused by the molding process, such as die lines and uneven cooling during sheet extrusion molding, and to relatively compare the inherent optical properties (transparency) of the resin composition, an evaluation was performed using a 2 mm thick plate produced by injection molding, which has excellent surface smoothness.

[0062] <Vicat softening temperature> In this embodiment, the Vicat softening temperature of the styrene-based resin composition is preferably 60°C to 85°C, more preferably 61°C to 82°C, even more preferably 62°C to 79°C, even more preferably 62°C to 76°C, and even more preferably 62°C to 73°C. By setting the Vicat softening temperature of the styrene-based resin composition to 60°C or higher, an effect of improving the heat resistance of the composition can be obtained, and by setting it to 85°C or lower, a balance between appropriate visibility and excellent shrinkage characteristics can be achieved. The method for measuring the Vicat softening temperature in this specification is measured in accordance with ISO 306.

[0063] The impact strength of the styrene-based resin composition in this embodiment, measured by a notched Charpy impact test at 23°C, is 15 J / cm². 2 Preferably, it is 16 J / cm² or more. 2 More than 28J / cm 2More preferably, the following is 17 J / cm 2 More than 26J / cm 2 The following is particularly preferred: 18 J / cm² 2 More than 24J / cm 2 The following applies: When the impact strength of the styrene-based resin composition is within the above range, it is preferable from the viewpoint of balancing appropriate fluidity and excellent impact strength.

[0064] [Method for producing styrene-based resin compositions] In this embodiment, the method for producing the styrene-based resin composition is not particularly limited, but a polymerization method similar to that of known rubber-modified styrene-based resins can be used. The polymerization method described above can be carried out by bulk polymerization (or solution polymerization) using a polymerization solution containing a styrene monomer, a first (meth)acrylic acid ester, a second (meth)acrylic acid ester, a vinyl monomer (i) added as needed, and a solvent added as needed, in the presence of a rubbery polymer; or by bulk-suspension polymerization, which transitions to suspension polymerization during the reaction; or by emulsion graft polymerization, in which a styrene monomer and a vinyl monomer (i) added as needed are polymerized in the presence of a rubbery polymer latex. In bulk polymerization, the product can be carried out by continuously supplying a mixed solution containing the rubbery polymer, styrene monomer, first (meth)acrylic acid ester, second (meth)acrylic acid ester, a vinyl monomer (i) added as needed, and an organic solvent, organic peroxide, and / or chain transfer agent as needed, to a polymerization apparatus configured by connecting a fully mixed reactor or a tank reactor and a plurality of tank reactors in series.

[0065] In this embodiment, another method for producing the styrene-based resin composition is to polymerize the matrix phase of the styrene-based resin composition, and then compound, melt, knead, or granulate it with rubbery polymer particles. The polymerization method for copolymer (A), which is the matrix phase of the styrene-based resin composition, is not particularly limited, but for example, a bulk polymerization method or a solution polymerization method can be suitably employed as a radical polymerization method. The polymerization method mainly comprises a polymerization step of polymerizing polymerization raw materials (monomer components) and a defoliation step of removing volatile components such as unreacted monomers and polymerization solvents from the polymerization product. Furthermore, the method of blending, melting, kneading, and granulating each raw material component is not particularly limited, and methods commonly used in the production of styrene-based resin compositions can be used. For example, a styrene-based resin composition can be obtained by blending (mixing) each of the above components in a drum tumbler, Henschel mixer, etc., melting and kneading them using a Banbury mixer, single-screw extruder, twin-screw extruder, kneader, etc., and then granulating them with a rotary cutter, fan cutter, etc. The resin temperature during melting and kneading is preferably 180 to 240°C. In order to achieve the target resin temperature, it is preferable to set the cylinder temperature of the extruder, etc. to 10 to 20°C lower than the resin temperature. If the resin temperature is below 180°C, mixing will be insufficient, which is undesirable. On the other hand, if the resin temperature exceeds 240°C, thermal decomposition of the resin will occur, which is undesirable.

[0066] Examples of polymerization initiators used in the above polymerization include organic peroxides such as peroxyketals like 2,2-bis(t-butylperoxy)butane, 1,1-bis(t-butylperoxy)cyclohexane (perhexa-C), and n-butyl-4,4-bis(t-butylperoxy)valerate; dialkyl peroxides such as di-t-butylperoxide (perbutyl-D), t-butylcumylperoxide, and dicumylperoxide; diacyl peroxides such as acetylperoxide and isobutyrylperoxide; peroxydicarbonates such as diisopropylperoxydicarbonate; peroxyesters such as t-butylperoxyacetate; ketone peroxides such as acetylacetone peroxide; and hydroperoxides such as t-butylhydroperoxide. Of these, 1,1-bis(t-butylperoxy)cyclohexane is preferred from the viewpoint of decomposition rate and polymerization rate. It is preferable to add 0.005 to 0.08% by mass relative to the total amount of monomers. Examples of chain transfer agents used in the above polymerization include mercaptans such as n-dodecyl mercaptan, t-dodecyl mercaptan, and n-octyl mercaptan, α-methylstyrene linear dimer, 1-phenyl-2-fluorene, dibentene, chloroform, terpenes, halogen compounds, and turpentines such as terepinolene. There are no particular restrictions on the amount of chain transfer agent used, but it is generally preferable to add about 0.005 to 0.3% by weight relative to the monomer.

[0067] As for the polymerization method described above, solution polymerization using a polymerization solvent can be employed as needed. Examples of polymerization solvents that can be used include aromatic hydrocarbons, such as ethylbenzene and dialkyl ketones, such as methyl ethyl ketone. These may be used individually or in combination of two or more. Other polymerization solvents, such as aliphatic hydrocarbons, can be further mixed with aromatic hydrocarbons as long as they do not reduce the solubility of the polymerization product. It is preferable to use these polymerization solvents in an amount not exceeding 25 parts by mass per 100 parts by mass of total monomers. If the amount of polymerization solvent exceeds 25 parts by mass per 100 parts by mass of total monomers, the polymerization rate tends to decrease significantly, and the mechanical strength of the resulting resin tends to decrease significantly. Adding 5 to 20 parts by mass per 100 parts by mass of total monomers before polymerization is preferable in terms of quality uniformity and polymerization temperature control.

[0068] In this embodiment, there are no particular restrictions on the apparatus used in the polymerization method described above, and it may be appropriately selected according to general polymerization methods for styrene-based resins. For example, when bulk polymerization is employed, a polymerization apparatus consisting of one or more fully mixed reactors can be used. There are also no particular restrictions on the devolatilization process. For example, when bulk polymerization is employed, polymerization is carried out until the amount of unreacted monomer is preferably 50% by mass or less, more preferably 40% by mass or less, and then devolatilization is performed by a known method to remove volatile components such as the unreacted monomer. More specifically, conventional devolatilization apparatus such as a flash drum, twin-screw devolatilizer, thin-film evaporator, or extruder can be used, but a devolatilization apparatus with a small retention area is preferred. The temperature of the devolatilization treatment is usually around 190 to 280°C, more preferably 190 to 260°C. The pressure of the devolatilization treatment is usually around 0.13 to 4.0 kPa, preferably 0.13 to 3.0 kPa, and more preferably 0.13 to 2.0 kPa. Preferred defloration methods include removing volatile components by reducing the pressure under heating, and removing them by passing them through an extruder or the like designed for the purpose of removing volatile components.

[0069] [Molded articles, sheets, and films] The molded article of this embodiment can be obtained by molding the above-mentioned styrene-based resin composition. The molded article is not particularly limited as long as it is obtained by molding the above-mentioned styrene-based resin composition, but it is preferably an extruded article, a sheet, or a film. An example of a secondary molded article using the extruded sheet or film of this embodiment is a food container or a shrink film. The food container may be manufactured by directly molding (shaping) it at the outlet of the extruder, or by further molding a sheet obtained using an extruder.

[0070] The sheet of this embodiment may be non-foamed or foamed. Furthermore, the sheet of this embodiment may be used by layering a styrene-based resin composition with a known polystyrene-based resin, or by layering a resin other than the polystyrene-based resin in addition to, or instead of, the polystyrene-based resin layer. Examples of resins other than polystyrene-based resins include PC resin, ABS resin, PP resin, PP / PS resin, PET resin, nylon resin, and styrene-butadiene copolymer (SBC).

[0071] The following describes suitable molded articles, such as sheets and films, using the styrene-based resin composition of this embodiment. In this specification, a sheet refers to an article with a thickness of 100 μm or more, and a film refers to an article with a thickness of less than 100 μm. (Method for manufacturing sheets of styrene resin composition) The sheet of this embodiment contains the above-mentioned styrene-based resin composition. The sheet of this embodiment can be used to produce molded articles by the above-mentioned melt-kneading molding machine, or by using the obtained styrene-based resin composition pellets as a raw material, through injection molding, injection compression molding, extrusion molding, blow molding, press molding, vacuum molding, foam molding, and the like.

[0072] <Extruded Sheet> This embodiment provides an extruded sheet formed using the styrene-based resin composition of the present invention described above. The extruded sheet may be either non-foamed or foamed. A commonly known method can be used as the method for manufacturing the extruded sheet. For a non-foamed extruded sheet, a method can be used in which a single-screw or twin-screw extruder equipped with a T-die is used, and a device for taking up the sheet with a uniaxial stretcher or twin-screw stretcher is used. For a foamed extruded sheet, a method can be used in which an extruder foam molding machine equipped with a T-die or circular die is used.

[0073] -Foam extruded sheet- In this embodiment, when forming a foamed extruded sheet, commonly used substances can be used as the foaming agent and foaming nucleation agent during extrusion foaming. As the foaming agent, butane, pentane, chlorofluorocarbons (CFCs), carbon dioxide, water, etc., can be used, with butane being preferred. As the foaming nucleation agent, talc, etc., can be used. In this embodiment, the foamed extruded sheet is preferably 0.5 mm to 5.0 mm thick, has an apparent density of 50 g / L to 300 g / L, and has a basis weight of 80 g / m². 2 ~300g / m 2 It is preferable that this is the case. The foamed extruded sheet of the present invention may be multilayered, for example, by further laminating a film. The type of film used may be any type commonly used for polystyrene.

[0074] -Non-foamed extruded sheet- In this embodiment, the thickness of the non-foamed sheet is preferably, for example, about 0.1 to 1.0 mm, from the viewpoint of rigidity and thermoforming cycle. Furthermore, the uniaxial sheet may be formed by normal low-magnification roll stretching alone, and for the biaxially oriented sheet, it is preferable in terms of strength to stretch it by about 1.2 to 7 times in the flow direction (MD) on the rolls, and then stretch it by about 1.2 to 7 times in the vertical direction (TD) on the tenter. In addition, the non-foamed sheet may be used in multilayer formation with styrene-based resins such as polystyrene resin other than styrene-based resin compositions. Furthermore, it may be used in multilayer formation with resins other than styrene-based resins. Examples of resins other than styrene-based resins include PET resin and nylon resin.

[0075] <Biaxially stretched sheet> Another embodiment of the sheet of this embodiment is a biaxially oriented sheet formed using the styrene-based resin composition described above. A commonly known method can be used to manufacture the biaxially oriented sheet. The biaxially oriented sheet may be produced by stretching it in the flow direction (MD) with a roll and then stretching it in the vertical direction (TD) with a tenter, or by sequentially or simultaneously biaxially stretching a styrene-based resin composition that has been formed into a sheet with a tenter while it is heated to approximately the Vicat softening temperature of the composition + 10 to 40°C.

[0076] In this embodiment, for strength, it is preferable to stretch the biaxially stretched sheet to approximately 1.2 to 7.0 times in the MD direction and 1.2 to 7.0 times in the TD direction. The average thickness of the biaxially oriented sheet in this embodiment is preferably 0.1 mm or more, more preferably 0.15 mm or more, and even more preferably 0.2 mm or more, in order to ensure the strength, especially the rigidity, of the sheet and the container. On the other hand, from the viewpoint of economy, it is preferably 0.7 mm or less, more preferably 0.6 mm or less, and even more preferably 0.5 mm or less. In this embodiment, it is preferable that the orientation relaxation stresses in the longitudinal and transverse directions of the biaxially oriented sheet are in the range of 0.4 to 1.3 MPa. By adjusting the orientation relaxation stresses within this range, the strength of the molded product of the biaxially oriented sheet can be maintained.

[0077] When the biaxially oriented sheet of this embodiment is used as a food packaging container, a known anti-fogging agent may be applied to at least one side of the biaxially oriented sheet to prevent fogging caused by moisture volatilizing from the food. Examples of such anti-fogging agents include nonionic surfactants such as sucrose fatty acid esters and polyglycerin fatty acid esters, and polyether-modified silicone oil. The method for applying the above-mentioned anti-fogging agent to the biaxially oriented sheet of this embodiment is not particularly limited, and a simple method is to use a roll coater, knife coater, gravure roll coater, etc. Spraying, immersion, etc. can also be used. Furthermore, the wettability of the surface of the biaxially oriented sheet may be improved by surface treatment such as corona treatment, ozone treatment, or primer treatment before application.

[0078] (Method for manufacturing a styrene-based resin film) The method for manufacturing the film of this embodiment is not particularly limited, but for example, an extrusion molding method is preferred. If the film of this embodiment has a multilayer structure, each layer can be molded simultaneously by co-extrusion. If the co-extrusion method is a so-called T-die method, the lamination method can be a feed block method, a multi-manifold method, or a method combining these.

[0079] When the film of this embodiment is a laminate and is manufactured by co-extrusion, the raw materials constituting each layer of the laminate are fed into an extruder and then extruded by a die to obtain a sheet-like body in which each layer is laminated. Then, the sheet-like body is cooled and solidified while being wound up on a take-up roll, and then stretched uniaxially or biaxially to obtain the film of this embodiment. Examples of the stretching method include roll stretching, tenter stretching, or a combination thereof. The temperature during stretching is changed according to the softening temperature and shrinkage characteristics of the resin constituting the film, but is preferably 65°C to 120°C, and more preferably 70°C to 115°C. The stretch ratio in the main shrinkage direction is changed according to the stretching temperature, etc., but is preferably 3 to 7 times, and more preferably 4 to 6 times.

[0080] <Secondary molded products> Another aspect of this embodiment provides a secondary molded product formed using the sheet or film described above, particularly a food container, a carrier tape for transporting electronic components, or a shrink film. The sheet or film of this embodiment can be used to produce, for example, food containers, such as lids for bento boxes or containers for side dishes, formed by vacuum forming, or carrier tapes for transporting electronic components. Furthermore, in this embodiment, the method for manufacturing a container obtained by molding from a sheet body is not particularly limited, and examples include pressure forming and vacuum forming.

[0081] A shrink film can be produced, for example, from the film of this embodiment. The shrink film of this embodiment has a substrate containing the styrene-based resin composition of this embodiment, and resin layers laminated on both sides of the substrate. A printed layer may also be provided on the surface of the resin layer. Examples of resins constituting the resin layer include styrene-based elastomers, propylene-based resins, ethylene-based resins, cyclic olefin-based resins, and petroleum resins. In this embodiment, examples include cyclic olefin-based resins, ethylene-based resins, petroleum resins, and mixed resins thereof. Examples of the styrene-based elastomers include styrene-ethylene-butylene-styrene block copolymer (SEBS), styrene-ethylene-butylene-ethylene block copolymer (SEBC), and styrene-butadiene copolymer (SBC). The propylene-based resin is preferably a binary or ternary random copolymer having propylene as the main component and α-olefin as the copolymer component. Examples of α-olefins include ethylene, 1-butene, 1-pentene, 1-hexene, and 1-octene, and may contain two or more types of α-olefins. More specifically, examples include a binary random copolymer of propylene and ethylene, and a ternary random copolymer of propylene, ethylene, and butene. Examples of the cyclic olefin resin include random copolymers of ethylene or propylene with cyclic olefins, ring-opening polymers of cyclic olefins or copolymers with the α-olefin, hydrogenated polymers of the polymers, or graft-modified unsaturated carboxylic acids and their derivatives.

[0082] Examples of the aforementioned cyclic olefins include norbornene, 6-methylnorbornene, 6-ethylnorbornene, 5-propylnorbornene, 6-n-butylnorbornene, 1-methylnorbornene, 7-methylnorbornene, 5,6-dimethylnorbornene, 5-phenylnorbornene, 5-benzylnorbornene, and norbornene and its derivatives. Furthermore, examples of tetracyclododecene and its derivatives include tetracyclododecene, 8-methyltetracyclo-3-dodecene, 8-ethyltetracyclo-3-dodecene, 5,10-dimethyltetracyclo-3-dodecene, and tetracyclododecene. [Examples]

[0083] The present invention will be specifically described below with reference to examples and comparative examples, but the present invention should not be interpreted as being limited to these examples. The methods for analyzing and evaluating the resin compositions in the examples and comparative examples are as follows. (1) Method for measuring the content of styrene monomer units, first (meth)acrylic acid ester monomer units, and second (meth)acrylic acid ester monomer units The content (mass%) of styrene monomer units (a1), first (meth)acrylic acid ester monomer units and second (meth)acrylic acid ester monomer units in the styrene resin composition is determined by proton nuclear magnetic resonance ( 1 The resin composition was quantified from the integral ratio of the spectra measured using a 1H-NMR spectrometer. Sample preparation: 30 mg of the resin composition was dissolved in 0.75 mL of d6-DMSO by heating at 60°C for 4 to 6 hours. Measuring equipment: JNM ECA-500 manufactured by JEOL Ltd. Measurement conditions: Measurement temperature 25°C, observed nucleus 1H, number of cumulative measurements 64, repetition time 11 seconds

[0084] (2) Measurement of the content of conjugated diene monomer units in the styrene resin composition The content (mass%) of conjugated diene monomer units derived from the rubbery polymer in the styrene resin composition was measured as follows. 0.4 g of the styrene resin composition for containers was accurately weighed into a volumetric flask (let this mass be W), 75 mL of chloroform was added and thoroughly dispersed, then 20 mL of a solution of 18 g of iodine monochloride dissolved in 1000 mL of carbon tetrachloride was added, and the mixture was stored in a cool, dark place. After 8 hours, chloroform was added and the mixture was brought to the mark. 25 mL of this mixture was taken, 60 mL of a solution of 10 g of potassium iodide dissolved in a mixture of 800 mL of water and 200 mL of ethanol was added, and the mixture was titrated with a solution of 10 g of sodium thiosulfate dissolved in 1000 mL of water (let this molar concentration be x). The main sample was A mL and the blank was B mL, and the content (mass%) of conjugated diene monomer units derived from the rubbery polymer was calculated using the following formula. Conjugated diene monomer units derived from rubbery polymer (amount of butadiene) = 10.8 × x × (BA) / W

[0085] (3) Measurement of molecular weight The number-average molecular weight, weight-average molecular weight, and Z-average molecular weight of polymer (A) or the matrix phase, as well as the molecular weight of polymers with a molecular weight of 800,000 or more, were calculated using gel permeation chromatography (GPC) under the following conditions. Equipment: Tosoh HLC-8420 Separation column: Two Resonaq KF 606M columns connected in series. Guard column: Resonaq KF G4A Solvent used for measurement: Tetrahydrofuran (THF) Sample preparation: 5 mg of the sample was dissolved in 10 mL of solvent and filtered through a 0.45 μm filter. Injection volume: 10μL Measurement temperature: 40℃ Flow rate: 0.35mL / min Detector: Ultraviolet-Visible detector (UV-8420) Eleven types of TSK standard polystyrene manufactured by Tosoh Corporation (F-850, F-450, F-128, F-80, F-40, F-20, F-10, F-4, F-2, F-1, A-5000) were used to create the calibration curve. The calibration curve was created using an approximation formula for a linear curve.

[0086] (4) Measurement of refractive index The refractive indices of the matrix phase and the rubbery polymer particles were measured at 25°C using an Abbe refractometer after separating the matrix phase and rubbery polymer particles using the same procedure as described in section (6) "(6) Measurement of the content of insoluble matter and swelling index of methyl ethyl ketone / methanol (9 / 1) (a mixed solvent prepared by mixing the weight of methyl ethyl ketone and the weight of methanol in a ratio of 9:1)." The toluene solvent was then dried. The absolute difference in refractive index between the matrix phase and the rubbery polymer particles was calculated from the measured values ​​as the absolute difference between the two.

[0087] (5) Measurement of toluene-insoluble content and swelling index The toluene-insoluble content (mass%) and swelling index of the styrene resin composition for containers were measured as follows. 1.00 g of the styrene resin composition was accurately weighed into a sedimentation tube (this mass is denoted as W1), 20 ml of toluene was added, and the mixture was shaken at 23°C for 2 hours. Then, it was centrifuged in a centrifuge (Sakuma Seisakusho Co., Ltd., SS-2050A, rotor: 6B-N6L) at a temperature of 4°C, a rotation speed of 20,000 rpm, and a centrifugal acceleration of 45,100 × G for 60 minutes. The sedimentation tube was slowly tilted to approximately 45 degrees, and the supernatant was removed by decantation. The mass of the toluene-insoluble content was accurately weighed (this mass is denoted as W2), and subsequently, it was vacuum-dried at 160°C and below 3 kPa for 1 hour. After cooling to room temperature in a desiccator, the mass of the toluene-insoluble content was accurately weighed (this mass is denoted as W3). The toluene-insoluble content and swelling index of the rubber-modified styrene resin composition, i.e., the content and swelling index of rubbery polymer particles in the styrene resin composition for containers, were determined using the following formula. Swelling index of toluene-insoluble components = W2 / W3

[0088] (6) Measurement of insoluble matter content and swelling index of methyl ethyl ketone / methanol (9 / 1) (A mixed solvent prepared by mixing the weight of methyl ethyl ketone and the weight of methanol in a ratio of 9:1 is called methyl ethyl ketone / methanol (9 / 1)). The content (mass%) of methyl ethyl ketone / methanol (9 / 1) insoluble matter and the swelling index of the styrene resin composition for containers were measured as follows. 1.00 g of the styrene resin composition was accurately weighed into a sedimentation tube (this mass was designated as W1), 20 ml of methyl ethyl ketone / methanol (9 / 1) was added, and the mixture was shaken at 23°C for 2 hours. The mixture was then centrifuged in a centrifuge (Sakuma Seisakusho Co., Ltd., SS-2050A, rotor: 6B-N6L) at a temperature of 4°C, a rotation speed of 20,000 rpm, and a centrifugal acceleration of 45,100 × G for 60 minutes. The sedimentation tube was slowly tilted to approximately 45 degrees, and the supernatant was removed by decantation. The mass of the insoluble matter containing methyl ethyl ketone / methanol (9 / 1) was accurately weighed (denoted as W2), and subsequently, it was vacuum-dried for 1 hour at 160°C and 3kPa or less. After cooling to room temperature in a desiccator, the mass of the toluene-insoluble matter was accurately weighed (denoted as W3). The toluene-insoluble content and swelling index of the rubber-modified styrene resin composition, i.e., the content and swelling index of rubbery polymer particles in the styrene resin composition for containers, were determined using the following formula. Methyl ethyl ketone / methanol (9 / 1) insoluble content = W3 / W1 × 100

[0089] (7) Measurement of the average particle size of rubbery polymer particles Machine used: Malvern Panalyticai mastersizer3000 Dispersion medium used: DMF Method for measuring average particle size: Using a mastersizer3000 (product name) manufactured by Malvern Panalyticai, 0.05 g of pelletized styrene resin composition (for example, the styrene resin composition obtained in the Examples and Comparative Examples) was placed in approximately 5 ml of dimethylformamide and left for approximately 2 to 5 minutes. Next, the dissolved dimethylformamide was measured at an appropriate particle concentration, and the median diameter (D50%) based on volume was taken as the average particle diameter. Furthermore, the method for measuring the average particle diameter of the rubbery polymer particles described above can be applied to the method for measuring the average particle diameter of rubbery polymer particles contained in the entire styrene resin composition and the rubber-modified styrene resin that is the raw material for the styrene resin composition.

[0090] (8) Measurement of meltmass flow rate (MFR) The melt mass flow rate (MFR) (g / 10 min) of the styrene-based resin composition was measured in accordance with JIS K7210 (200°C, load 49N).

[0091] (9) Vicat softening temperature In accordance with JIS K7206, the Vicat softening temperature (°C) of the styrene-based resin compositions obtained in the following examples and comparative examples was measured. The load was 49 N and the heating rate was 50 °C / h.

[0092] (10) DuPont impact strength A styrene-based resin composition was extruded using a 30mmφ sheet extruder (manufactured by Soken Co., Ltd.) to produce a sheet with a thickness of 0.3mm. The obtained sheet was measured in accordance with JIS K5600-5-3 using a 12.5mm diameter missile, a 16.5mm diameter tray, and a 0.2kg weight.

[0093] (11) Measurement of total light transmittance and haze Using a 30mmφ sheet extruder (manufactured by Soken Co., Ltd.), the styrene-based resin compositions prepared in the examples and comparative examples were extruded under the following conditions to produce sheets with a thickness of 0.3mm. The total light transmittance (%) of the obtained sheets was measured in accordance with JIS K7361-1. In addition, the haze (%) was measured in accordance with JIS K7136. <Extrusion conditions> Using a styrene-based resin composition, a sheet of 0.3 ± 0.02 mm was produced with the extruder set to a resin melting zone temperature of 200-230°C, a T-die temperature of 230°C, and a roll temperature of 60-80°C, at a discharge rate of 6 kg / hour.

[0094] (12) Charpy impact test (with notch) (kJ / m 2 ) (12-1) Dumbbell molding of styrene resin composition Each styrene-based resin composition produced in the examples and comparative examples was molded into a 4mm Type A dumbbell using a Toshiba Machine Co., Ltd. EC60N under the following conditions. Pellet drying: Dry at a temperature below Tg for at least 2 hours. Measurement: 63mm Ejection time: 20 seconds Pressure holding switch: Short shot point of 10mm or less Holding pressure: During short shots, MAX injection pressure at 0 MPa × 1.0 MPa Holding time: 10 seconds Cylinder temperature: 200-220-210-190℃ from nozzle side to hopper side Screw rotation speed: 100 revolutions / minute Cushion: 4.5~5.5mm Mold temperature: 60℃ Cooling time: 25 seconds (12-2) Measurement of Charpy impact strength A 4mm thick dumbbell piece obtained in the previous section (12-1) was used to prepare an 80×10×4mm test piece with a notch using a cutting machine. The Charpy impact strength (with notch) was measured in accordance with ISO179(1eA). The average value of n5 was used as the measured value.

[0095] (13) Evaluation of heat shrinkage rate A film (50 μm thick) stretched 1.3 times in the MD direction and 5 times in the TD direction using a biaxial stretching machine (manufactured by Toyo Seiki Co., Ltd.) was cut into 10 x 10 cm pieces, immersed in 80°C hot water for 10 seconds, and the shrinkage rate was measured. The contraction rate was calculated using the following formula. Contraction rate (%) = [{(X1-X0) / X0}] × 100 (In the above formula, X0 represents the length in the TD direction of the film (thickness 50 μm) before immersion in 80°C hot water for 10 seconds, and X1 represents the length in the TD direction of the film (thickness 50 μm) after immersion in 80°C hot water for 10 seconds.)

[0096] (14) Film tensile test at 4°C (evaluation based on breakage of 50% or less) Using a biaxial stretching machine (manufactured by Toyo Seiki Co., Ltd.), a film (thickness 50 μm) stretched 1.2 times in the MD direction and 5 times in the TD direction was cut into dumbbell shapes (width 6 mm, chuck distance 80 mm). Tensile evaluation was performed at 4°C, and the number of times the film broke at 50% or less was evaluated. Equipment: Small tensile testing machine with constant temperature chamber, manufactured by Instron. Test conditions: Tensile speed 100 mm / min

[0097] "raw materials" The following materials were used in the examples and comparative examples. <Monovinyl compounds> Styrene (HSP: 19.1 (MPa)) 1 / 2 ): Styrene monomer [manufactured by Asahi Kasei Corporation] <First (meth)acrylate ester> Butyl acrylate (HSP: 17.5 (MPa)) 1 / 2 ): Manufactured by Wako Pure Chemical Industries, Ltd. <Second (meth)acrylate ester> Methyl methacrylate (HSP: 17.9 (MPa)) 1 / 2 ): Manufactured by Asahi Kasei Corporation <Rubber-like polymer particles> Styrene-butadiene rubber: [Manufactured by Asahi Kasei Corporation: Asaprene (registered trademark) 625A] <others> Polymerization initiator 1: 1,1-bis(t-butylperoxy)cyclohexane [NOF Corporation: Perhexa C] Chain transfer agent 2: α-methylstyrene dimer [Manufactured by NOF Corporation: H-dimer] Ethylbenzene: [Manufactured by Wako Pure Chemical Industries, Ltd.] Higher fatty acid compound: Stearic acid [Manufactured by Dainichi Chemical Industry Co., Ltd.: Daiwax STF] Antioxidant: Octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanoate [BASF Japan: Irganox 1076] Plasticizer: Liquid paraffin [Manufactured by Sanko Chemical Industry Co., Ltd.: PS-350S]

[0098] "Example 1" Preparation of styrene resin composition (1) The product was manufactured using a polymerization apparatus consisting of two reactors equipped with stirrers connected in series, followed by an extruder with a vacuum vent. Specifically, a raw material solution was prepared consisting of 42.0 parts by mass of styrene, 25.2 parts by mass of methyl methacrylate, 16.8 parts by mass of butyl acrylate, 9.1 parts by mass of a rubbery polymer of type BS (B: butadiene block, S: styrene block) with a styrene content of 38% by mass, 7 parts by mass of ethylbenzene, 0.02 parts by mass of 1,1-bis(t-butylperoxy)cyclohexane, 0.05 parts by mass of α-methylstyrene dimer, and 0.134 parts by mass of an antioxidant. This raw material solution was supplied to the reactor for polymerization. The prepared raw material solution was continuously supplied at a rate of 3.2 L / hour to a 6.2 L laminar flow reactor-1 equipped with a stirrer and capable of temperature control in three zones, and the temperature was adjusted to 124°C / 127°C / 130°C. The stirrer rotation speed was set to 50 revolutions per minute. Next, the reaction mixture was sent to a 6.2 L laminar flow reactor-2, which was connected in series with laminar flow reactor-1, and equipped with a stirrer and capable of temperature control in three zones. The temperature was set to 128°C / 129°C / 130°C. Then, the reaction mixture was sent to a 6.2 L laminar flow reactor-3, which was connected in series with laminar flow reactor-2, and equipped with a stirrer and capable of temperature control in three zones. The temperature was set to 130°C / 131°C / 132°C. Next, the reaction mixture from laminar flow reactor-3 was supplied to a two-stage vacuum vented extruder adjusted to 210~245°C and 1.5~2.0 kPa to remove unreacted monomers and volatile components such as solvents, and the resin extruded in strand form was cut to obtain pelletized styrene resin (1). The solid content concentration of the obtained styrene-based resin (1) was measured using the formula [(mass of sample after drying / mass of sample before drying) × 100%] after drying the polymerization solution at 215°C under reduced pressure of 2.5 kPa for 30 minutes. The physical properties of the obtained styrene-based resin composition (1) are shown in Table 1.

[0099] Examples 2-4 Styrene-based resin compositions (2) to (4) were obtained in the same manner as in Example 1, except that the conditions and additive formulations were changed as shown in Table 1. The physical properties and evaluation results of styrene-based resin compositions (2) to (4) of Examples 2 to 4 are shown in Table 1.

[0100] "Comparative Examples 1-13" Comparative Examples 1 to 13 were prepared in the same manner as Example 1, except that the conditions were changed as shown in Table 1, to obtain comparative styrene-based resin compositions (1) to (13). The physical properties and evaluation results of comparative styrene-based resin compositions (1) to (13) of Comparative Examples 1 to 13 are shown in Tables 1 and 2.

[0101] Example 5 The styrene-based resin composition (2) obtained in Example 2 was placed in an extruder with a barrel temperature of 210°C and extruded from a die at 220°C into a single-layer sheet, which was then cooled and solidified on a take-up roll at 30°C. Next, the resin sheet was stretched 1.2 times in the MD direction and 5 times in the TD direction in a tenter stretcher with a preheating zone of 100°C and a stretching zone of 100°C. The average thickness of the resulting film was 55-65 μm.

[0102] "Example 6" The pelletized styrene resin (1) prepared in Example 1 was extruded as an intermediate layer, and SBC (styrene-butadiene block copolymer) was laminated as the outermost layer adjacent to and sandwiching the intermediate layer. The layer thickness ratio was adjusted to 1 / 3 / 1 in the order of outermost layer / intermediate layer / outermost layer, and the three-layer unstretched raw material was extruded from a T-die (T-die temperature 210°C) (cylinder temperature 200°C), stretched 1.3 times in the flow direction (MD) on a roll, and then stretched 5 times in the vertical direction (TD) on a tenter to obtain a shrink film with a thickness of 45-55 μm.

[0103] [Table 1]

[0104] [Table 2] [Industrial applicability]

[0105] The styrene-based resin composition obtained in this invention exhibits excellent impact strength at room temperature and low temperature ranges, and a high shrinkage rate when heated. Therefore, the styrene-based resin composition of this invention can be widely used in non-foamed or foamed sheets, films, shrink films, containers, or molded articles by injection molding (electrical product parts, toys, daily necessities, various industrial parts, etc.).

Claims

1. A styrene-based resin composition comprising a matrix phase containing a copolymer (A) having styrene monomer units, a first (meth)acrylic acid ester monomer unit, and a second (meth)acrylic acid ester monomer unit, and rubbery polymer particles in which the styrene monomer units, the first (meth)acrylic acid ester monomer unit, and the second (meth)acrylic acid ester monomer unit are graft copolymerized, The copolymer (A) comprises 40 to 60% by mass of the styrene monomer units, the first (meth)acrylic acid ester monomer units, and 10 to 30% by mass of the second (meth)acrylic acid ester monomer units, the second (meth)acrylic acid ester monomer units having a Hansen solubility parameter that approximates the Hansen solubility parameter of the styrene monomer to that of the first (meth)acrylic acid ester monomer. The refractive index of the matrix phase at 25°C is in the range of 1.540 to 1.560, and the absolute value of the refractive index difference between the rubbery polymer particles and the matrix phase is greater than 0 and less than or equal to 0.

040. The content of the rubbery polymer particles relative to the entire styrene-based resin composition is 20 to 35% by weight. The average particle size of the rubbery polymer particles is 0.80 μm or more and 2.5 μm or less. A styrene-based resin composition having a Vicat softening temperature of 60 to 75°C.

2. The resin composition according to claim 1, wherein the ratio of the first (meth)acrylic acid ester to the second (meth)acrylic acid ester in the matrix phase (first (meth)acrylic acid ester / second (meth)acrylic acid ester) is 0.1 or more and 5 or less.

3. The impact strength measured by a notched Charpy impact test at 23°C was 15 J / cm². ２ The resin composition according to claim 1.

4. The resin composition according to claim 1, wherein the matrix phase is contained as the sea phase and the rubbery polymer particles are contained as the island phase.

5. A sheet comprising the resin composition according to any one of claims 1 to 4.

6. A film comprising the resin composition according to any one of claims 1 to 4.

7. A molded article obtained by injection molding a resin composition according to any one of claims 1 to 4.

8. A container formed by molding the sheet body described in claim 5.

9. A shrink film comprising the resin composition according to any one of claims 1 to 4.

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