Styrene-unsaturated carboxylic acid resin composition, extruded sheet and container

Abstract

To provide: a styrene-unsaturated carboxylic acid resin composition excellent in heat resistance, transparency and cold impact resistance at a low temperature of about -30°C; an extrusion sheet using the same; and a vessel obtained by subjecting the extrusion sheet to secondary molding.SOLUTION: A styrene-unsaturated carboxylic acid resin composition includes: a styrene-unsaturated carboxylic acid resin (a) including a styrenic monomer unit (1) and an unsaturated carboxylic acid monomer unit; and a rubber modified styrenic resin (b) including a styrenic monomer unit (2) and an unsaturated carboxylic ester monomer unit. When the total amount of the styrene-unsaturated carboxylic acid resin (a) and the rubber modified styrenic resin (b) is 100 pts.mass, the content of the-styrene unsaturated carboxylic acid resin (a) is 60-95 pts.mass, and the content of the rubber modified styrenic resin (b) is 5-40 pts.mass. The content of the styrenic monomer unit (1) in the styrene-unsaturated carboxylic acid resin (a) is 60-98 mass% to the total styrene-unsaturated carboxylic acid resin (a); the content of the unsaturated carboxylic acid monomer unit is 2-40 mass%; and the content of the unsaturated carboxylic ester monomer unit in the rubber modified styrenic resin (b) is 1-55 mass% to the total rubber modified styrenic resin (b).SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a styrene-unsaturated carboxylic acid resin composition, a non-foamed and foamed extruded sheet molded using the styrene-unsaturated carboxylic acid resin composition, and a lunch box container and a lid material thereof obtained by secondary molding of the extruded sheet. [Background technology]

[0002] Styrene-unsaturated carboxylic acid resins, such as styrene-methacrylic acid copolymer resins, are excellent in heat resistance, transparency, and rigidity, and are inexpensive, and therefore are widely used in packaging materials for food containers such as boxed lunches and prepared foods, foam boards for insulating housing, diffusion plates for liquid crystal televisions containing a diffusion agent, etc. In particular, with the recent widespread use of high-power microwave ovens for commercial use in convenience stores and the like, styrene-unsaturated carboxylic acid resins are being used as materials for containers that can withstand the temperatures used during cooking in high-power microwave ovens, and for lids that seal or cover these containers.

[0003] In response to the recent trend of reducing food waste, there is an increasing demand to move from the conventional chilled transport / storage at around 0°C and microwave cooking at stores to frozen transport / storage at around -30°C and microwave cooking at stores in order to extend the expiration date of bento. The characteristics of containers that satisfy such demands require the maintenance of resin strength at low temperatures (around -30°C) that can reduce or suppress damage to the container during frozen transport / storage, and heat resistance that can reduce or suppress softening during microwave cooking, and in particular, the lid material must be transparent in addition to these characteristics. For example, Patent Document 1 discloses a technology for adding a rubber-modified styrene-based resin to a styrene-methacrylic acid-based resin as a material for such containers. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2017-214485 A Summary of the Invention [Problem to be solved by the invention]

[0005] The technology of the above-mentioned Patent Document 1 has heat resistance, transparency, and strength at room temperature, but is insufficient to impart cold impact resistance at a low temperature of about -30° C. Therefore, the problem to be solved by the present invention is to provide a styrene-unsaturated carboxylic acid resin composition excellent in heat resistance, transparency, and cold impact resistance at a low temperature of about -30° C., an extruded sheet using the same, and further a container and a lid material obtained by secondary molding of the extruded sheet. [Means for solving the problem]

[0006] The present inventors have conducted intensive research in light of the above problems, and as a result have succeeded in realizing a styrene-unsaturated carboxylic acid resin composition having excellent heat resistance, transparency, and cold impact resistance at a low temperature of about -30°C by kneading a styrene-unsaturated carboxylic acid resin (a) with a rubber-modified styrene resin (b) obtained by copolymerizing an unsaturated carboxylic acid ester monomer at a specific ratio, an extruded sheet using the composition, and a container obtained by secondary molding of the extruded sheet, thereby completing the present invention. That is, the present invention is as follows.

[0007] [1] The present invention relates to a styrene-unsaturated carboxylic acid resin composition comprising: (a) a styrene-unsaturated carboxylic acid resin containing (1) a styrene-based monomer unit and (a) an unsaturated carboxylic acid monomer unit; and (b) a rubber-modified styrene-based resin containing (2) a styrene-based monomer unit and (b) an unsaturated carboxylic acid ester monomer unit, the content of the styrene-unsaturated carboxylic acid resin (a) is 60 to 95 parts by mass, and the content of the rubber-modified styrene resin (b) is 5 to 40 parts by mass, when the total amount of the styrene-unsaturated carboxylic acid resin (a) and the rubber-modified styrene resin (b) is 100 parts by mass; the content of the styrene-based monomer unit (1) in the styrene-unsaturated carboxylic acid resin (a) is 60 to 98 mass% and the content of the unsaturated carboxylic acid monomer unit is 2 to 40 mass% based on the total mass of the styrene-unsaturated carboxylic acid resin (a); The styrene-unsaturated carboxylic acid resin composition is such that the content of the unsaturated carboxylic acid ester monomer unit in the rubber-modified styrene-based resin (b) is 1 to 55 mass % based on the total mass of the rubber-modified styrene-based resin (b).

[0008] [2] In the present invention, it is preferable that the styrene-unsaturated carboxylic acid resin (a) comprises a styrene-based monomer unit (1), an unsaturated carboxylic acid monomer unit and a (meth)acrylic acid ester monomer unit, and that the content of the styrene-based monomer unit (1) is 60 to 98 mass%, the content of the unsaturated carboxylic acid monomer unit is 2 to 20 mass%, and the content of the unsaturated carboxylic acid ester monomer unit is 0 to 20 mass parts, based on the entire styrene-unsaturated carboxylic acid resin (a).

[0009] [3] In the present invention, the (meth)acrylic acid ester monomer unit contained in the styrene-unsaturated carboxylic acid resin (a) preferably has an ester substituent having 10 or less carbon atoms.

[0010] [4] In the present invention, the melt mass flow rate is preferably 0.5 to 5.0 g / 10 min.

[0011] [5] In the present invention, the styrene-unsaturated carboxylic acid resin composition according to any one of the above [1] to [4], which has a Vicat softening temperature of 105° C. or higher.

[0012] [6] In the present invention, the styrene-unsaturated carboxylic acid-based composition further contains a monohydric alcohol having 16 or more carbon atoms, and preferably contains 0.1 to 1.0 part by mass of the monohydric alcohol having 16 or more carbon atoms when the total of the styrene-unsaturated carboxylic acid-based resin (a) and the rubber-modified styrene-based resin (b) is 100 parts by mass.

[0013] [7] In the present invention, the styrene-unsaturated carboxylic acid composition further contains an ethylene bisamide compound, and the ethylene bisamide compound is preferably contained in an amount of 0.001 to 0.05 parts by mass when the total of the styrene-unsaturated carboxylic acid resin (a) and the rubber-modified styrene resin (b) is 100 parts by mass.

[0014] [8] In the present invention, the styrene-unsaturated carboxylic acid-based composition further contains a hindered phenolic antioxidant, and when the total of the styrene-unsaturated carboxylic acid-based resin (a) and the rubber-modified styrene-based resin (b) is taken as 100 parts by mass, it is preferable that the hindered phenolic antioxidant is contained in an amount of 0.002 to 0.1 parts by mass.

[0015] [9] In the present invention, the rubber-modified styrene-based resin (b) has a rubber-like polymer containing a conjugated diene monomer unit, and a matrix resin containing the styrene-based monomer unit (2) and the unsaturated carboxylic acid ester monomer unit in which the rubber-like polymer is dispersed, and the content of the conjugated diene monomer unit is preferably 0.3 to 5.0 parts by mass when the total of the styrene-unsaturated carboxylic acid-based resin (a) and the rubber-modified styrene-based resin (b) is 100 parts by mass.

[10] In the present invention, the mixed resin of the styrene-unsaturated carboxylic acid resin (a) and the matrix resin of the rubber-modified styrene resin (b) preferably has a weight average molecular weight (Mw) of 100,000 to 350,000.

[0016]

[11] The present invention relates to a uniaxially and biaxially stretched non-foamed extruded sheet comprising the styrene-unsaturated carboxylic acid resin composition according to any one of the above [1] to [9].

[0017]

[12] The present invention relates to a foamed extruded sheet comprising the styrene-unsaturated carboxylic acid resin composition according to any one of the above [1] to [9].

[0018]

[13] The present invention relates to a molded article formed using the non-foamed extruded sheet according to the above item

[11] or the foamed extruded sheet according to the above item

[12] .

[0019]

[14] The present invention relates to a container or a lid material for a lunch box that can be cooked in a microwave oven, which is formed by secondary molding of the non-foamed extruded sheet described in

[11] above. Effect of the Invention

[0020] According to the present invention, a styrene-unsaturated carboxylic acid resin composition having excellent heat resistance, transparency, and cold impact resistance at low temperatures of about -30°C can be provided.

[0021] According to the present invention, it is possible to provide a foamed extruded sheet, a non-foamed extruded sheet, and a lid material for a lunch box container that can be used in a microwave oven, which have excellent heat resistance, transparency, and cold impact resistance at low temperatures of about -30°C. [Brief description of the drawings]

[0022] [Figure 1] FIG. 1 is a diagram showing a method for measuring stiffness of a tray container in this embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] Hereinafter, an embodiment of the present invention (hereinafter, referred to as "the present embodiment") will be described in detail. Note that the present invention is not limited to the following embodiment, and can be modified in various ways within the scope of the gist of the present invention.

[0024] [Styrene-unsaturated carboxylic acid resin composition] One aspect of the present invention is to provide a styrene-unsaturated carboxylic acid resin composition containing a styrene-unsaturated carboxylic acid resin (a) containing a styrene-based monomer unit (1) and an unsaturated carboxylic acid monomer unit, and a rubber-modified styrene-based resin (b) containing a styrene-based monomer unit (2) and an unsaturated carboxylic acid ester monomer unit, in which the content of the styrene-unsaturated carboxylic acid resin (a) is 60 to 95 parts by mass and the content of the rubber-modified styrene-based resin (b) is 5 to 40 parts by mass when the total of the styrene-unsaturated carboxylic acid resin (a) and the rubber-modified styrene-based resin (b) is 100 parts by mass (hereinafter, sometimes simply referred to as a resin composition).

[0025] In addition, the content of the styrene-based monomer unit (1) in the styrene-unsaturated carboxylic acid resin (a) is 60 to 98 mass%, and the content of the unsaturated carboxylic acid monomer unit is 2 to 40 mass%, based on the entire styrene-unsaturated carboxylic acid resin (a).

[0026] Furthermore, the content of the unsaturated carboxylate monomer unit in the rubber-modified styrene-based resin (b) is 1 to 55% by mass based on the total mass of the rubber-modified styrene-based resin (b).

[0027] The styrene-unsaturated carboxylic acid resin composition according to the present invention contains a predetermined amount of the styrene-unsaturated carboxylic acid resin (a) and the rubber-modified styrene resin (b), and therefore can achieve both excellent heat resistance and cold impact resistance. More specifically, since the styrene-unsaturated carboxylic acid resin (a) contains a large amount of so-called amorphous resin, the higher the glass transition temperature (Tg) of the entire composition, the more the heat softening resistance tends to improve. On the other hand, it is known that the material with a higher glass transition temperature (Tg) is more likely to lose its viscoelastic properties at low temperatures, and therefore the material with a lower glass transition temperature (Tg) has better cold resistance. Therefore, there is a trade-off between excellent heat resistance and excellent cold impact resistance. However, in the present invention, by containing a predetermined amount of the styrene-unsaturated carboxylic acid resin (a) and the rubber-modified styrene resin (b) having a specific composition, excellent heat resistance and excellent cold impact resistance are both achieved. In addition, by using a hindered phenol type antioxidant and / or a higher fatty acid surfactant in combination, a composition having both excellent heat resistance and cold shock resistance can be provided. <<Styrene-unsaturated carboxylic acid resin (a)>> The styrene-unsaturated carboxylic acid resin (a) in the present invention is a copolymer resin (hereinafter also simply referred to as resin (a)) consisting essentially of a styrene-based monomer unit and an unsaturated carboxylic acid monomer unit, and contributes to improving the heat resistance of the entire styrene-unsaturated carboxylic acid resin composition. The styrene-unsaturated carboxylic acid resin (a) may further contain monomer units (e.g., (meth)acrylic acid ester monomer units, other monomer units) other than the essential components of the styrene-based monomer unit and the unsaturated carboxylic acid monomer unit, if necessary. When the total of the styrene-unsaturated carboxylic acid resin (a) and the rubber-modified styrene-based resin (b) in the styrene-unsaturated carboxylic acid resin composition is 100 parts by mass, the content of the styrene-unsaturated carboxylic acid resin (a) is 60 to 95 parts by mass, preferably 70 to 93 parts by mass, more preferably 80 to 91 parts by mass, and even more preferably 85 to 89 parts by mass. If the content of the styrene-unsaturated carboxylic acid resin (a) is less than 60 parts by mass, the heat resistance cannot be sufficiently imparted, whereas if it is more than 95 parts by mass, the cold impact resistance described below decreases. <Styrene-based monomers (1)> In the styrene-unsaturated carboxylic acid resin (a) of this embodiment, the content of the styrene-based monomer unit (1) is 60 to 98 mass%, preferably 59.9 to 98 mass, more preferably 70 to 97 mass, even more preferably 80 to 96 mass, and even more preferably 82 to 91 mass% based on the entire styrene-unsaturated carboxylic acid resin (a). If the content of the styrene-based monomer unit (1) is less than 60 mass%, the flowability is reduced, and if it is more than 98 mass%, it becomes difficult to contain a desired amount of the unsaturated carboxylic acid monomer unit described below, and the effect of improving heat resistance by the unsaturated carboxylic acid monomer unit is not sufficiently obtained.

[0028] In this embodiment, the styrene-based monomer (1) is not particularly limited, but examples thereof include styrene, α-methylstyrene, β-methylstyrene, paramethylstyrene, orthomethylstyrene, metamethylstyrene, chlorostyrene, bromostyrene, etc. From an industrial viewpoint, styrene and α-methylstyrene are particularly preferred, and styrene is more preferred. As the styrene-based monomer (1), these may be used alone or in combination of two or more. <<Unsaturated carboxylic acid monomer>> In the styrene-unsaturated carboxylic acid resin (a) of this embodiment, the unsaturated carboxylic acid monomer unit plays a role in improving heat resistance. The content of the unsaturated carboxylic acid monomer unit is 2 to 40 mass%, preferably 3 to 30 mass%, more preferably 4 to 20 mass%, even more preferably 5 to 16 mass%, and even more preferably 6 to 13 mass% based on the entire styrene-unsaturated carboxylic acid resin (a). If this content is less than 2 mass%, the effect of improving heat resistance is insufficient. In addition, if the content of the unsaturated carboxylic acid monomer unit exceeds 40 mass%, it is not preferable because gelled matter in the resin increases, bubbles are generated during molding due to an increase in water absorption, and the viscosity becomes too high during production.

[0029] The unsaturated carboxylic acid monomer may be acrylic acid or methacrylic acid. From an industrial viewpoint, the unsaturated carboxylic acid monomer may be used alone or in combination of two or more. As the unsaturated carboxylic acid monomer, methacrylic acid is particularly preferred because it has a large effect of improving heat resistance. <<(Meth)acrylic acid ester monomer>> In the styrene-unsaturated carboxylic acid resin (a) of this embodiment, a (meth)acrylic acid ester monomer may be copolymerized in addition to the styrene monomer (1) and the unsaturated carboxylic acid monomer. That is, a preferred embodiment of the styrene-unsaturated carboxylic acid resin (a) is a copolymer having a styrene monomer unit (1) and an unsaturated carboxylic acid monomer unit, or a copolymer having a styrene monomer unit (1), an unsaturated carboxylic acid monomer unit, and a (meth)acrylic acid ester monomer unit. This further improves the surface hardness and mechanical strength. In addition, when the (meth)acrylic acid ester monomer is arranged adjacent to the unsaturated carboxylic acid monomer unit in the polymer chain, it is possible to obtain an effect of suppressing the crosslinking reaction between unsaturated carboxylic acids. In the styrene-unsaturated carboxylic acid resin (a) of this embodiment, the content of the (meth)acrylic acid ester monomer is preferably 0 to 20 mass%, more preferably 0.1 to 17 mass%, even more preferably 0.5 to 15 mass%, and even more preferably 2 to 13 mass%, based on the entire styrene-unsaturated carboxylic acid resin (a). If the content of the (meth)acrylic acid ester monomer exceeds 20%, it is not preferable from the viewpoint of increasing water absorption and increasing viscosity.

[0030] In this embodiment, the (meth)acrylic acid ester monomer unit is represented by the following general formula (1):

[0031] [ka]

[0032] (In the above general formula (1), R 1 represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, R 2 represents an ester substituent and represents an alkyl group having 1 to 12 carbon atoms.

[0033] In this embodiment, the ester substituent of the (meth)acrylic acid ester monomer unit (R 2 The number of carbon atoms in the alkyl group is preferably 10 or less, more preferably 8 or less, and even more preferably 4 or less. If the number of carbon atoms in the alkyl group exceeds 10, the effect of lowering heat resistance is significant, which is not preferred.

[0034] Examples of the (meth)acrylic acid ester monomer in this embodiment include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, cyclohexyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and decyl (meth)acrylate. These can be used alone or in combination. As the (meth)acrylic acid ester monomer, methyl (meth)acrylate or butyl (meth)acrylate is preferred because it has little effect on the decrease in heat resistance and is easily available industrially. <<Other monomers>> The styrene-unsaturated carboxylic acid resin (a) according to the present invention may further have other monomer units other than the above-mentioned styrene monomer unit (1) and unsaturated carboxylic acid monomer unit, and the optional (meth)acrylic acid ester monomer unit. That is, in this embodiment, the other monomer units may be copolymerized with monomers other than the above-mentioned two monomers without any particular limitation, as long as they are copolymerizable with the styrene monomer (1), the unsaturated carboxylic acid monomer, and the (meth)acrylic acid ester monomer unit, within a range that does not impair the effects of the invention. For example, examples of monomers other than the above-mentioned three monomers include maleic anhydride, maleic acid, fumaric acid, itaconic acid, (meth)acrylonitrile, dimethyl maleate, dimethyl fumarate, diethyl fumarate, ethyl fumarate, maleimide, and nucleus-substituted maleimide.

[0035] The contents of the styrene-based monomer unit (1), the unsaturated carboxylic acid monomer unit, the (meth)acrylic acid ester monomer unit, and the other monomer units in the styrene-unsaturated carboxylic acid resin (a) according to the present invention can be determined by proton nuclear magnetic resonance ( 1 It can be calculated from the integral ratio of the spectrum measured by a H-NMR spectrometer.

[0036] The melt flow rate of the styrene-unsaturated carboxylic acid resin (a) according to the present invention at 200°C may be preferably 0.3 to 3.0, more preferably 0.4 to 2.5, and even more preferably 0.4 to 2.0. When the melt flow rate is 0.3 or more, it is preferable from the viewpoint of fluidity, and when it is 3.0 or less, it is preferable from the viewpoint of mechanical strength of the resin. In the present disclosure, the melt flow rate is a value measured at 200°C under a load of 49N in accordance with ISO 1133.

[0037] The weight average molecular weight (Mw) of the styrene-unsaturated carboxylic acid resin (a) according to the present invention is preferably 100,000 to 400,000, more preferably 120,000 to 320,000. When the weight average molecular weight is 100,000 to 350,000, a resin having excellent practical balance between impact strength and fluidity can be obtained. The weight average molecular weight can be measured by gel permeation chromatography using polystyrene as the standard.

[0038] The Vicat softening temperature of the styrene-unsaturated carboxylic acid resin (a) according to the present invention is preferably 108 to 140° C., more preferably 109 to 135° C., even more preferably 110 to 130° C., and even more preferably 115 to 125° C. By making the Vicat softening temperature of the styrene-unsaturated carboxylic acid resin (a) 108° C. or higher, the heat resistance of the composition can be improved, and by making it 140° C. or lower, it becomes easy to knead with rubber-modified polystyrene. The Vicat softening temperature in this specification is measured according to ISO 306. <Production method of styrene-unsaturated carboxylic acid resin (a)> The method for producing the styrene-unsaturated carboxylic acid resin (a) of this embodiment will be described below.

[0039] The method for producing the styrene-unsaturated carboxylic acid resin (a) of the present invention preferably includes a step of mixing a styrene monomer (1), an unsaturated carboxylic acid monomer, and, if necessary, a (meth)acrylic acid ester monomer, a monohydric alcohol described below, and a solvent to prepare a mixed solution, a polymerization step of polymerizing the mixed solution to produce a reaction product, and a step of recovering the reaction product.

[0040] The polymerization method for the styrene-unsaturated carboxylic acid resin (a) is not particularly limited, but for example, a radical polymerization method, among which a bulk polymerization method or a solution polymerization method can be preferably used.

[0041] Specifically, the polymerization method mainly comprises a polymerization step of polymerizing polymerization raw materials (monomer components) and a devolatilization step of removing volatile matters such as unreacted monomers and polymerization solvent from the polymerization product.

[0042] The polymerization method according to this embodiment will be described below.

[0043] In this embodiment, when the polymerization raw material is polymerized to obtain the styrene-unsaturated carboxylic acid resin (a), a polymerization initiator is typically included in the polymerization raw material composition. Examples of the polymerization initiator include organic peroxides, such as peroxyketals such as 2,2-bis(t-butylperoxy)butane, 1,1-bis(t-butylperoxy)cyclohexane, and n-butyl-4,4-bis(t-butylperoxy)valerate, dialkyl peroxides such as di-t-butyl peroxide, t-butylcumyl peroxide, and dicumyl peroxide, diacyl peroxides such as acetyl peroxide and isobutyryl peroxide, peroxydicarbonates such as diisopropyl peroxydicarbonate, peroxyesters such as t-butylperoxyacetate, ketone peroxides such as acetylacetone peroxide, and hydroperoxides such as t-butyl hydroperoxide. Of these, 1,1-bis(t-butylperoxy)cyclohexane is preferred from the viewpoints of decomposition rate and polymerization rate.

[0044] In this embodiment, a chain transfer agent may be used as necessary during polymerization of the styrene-unsaturated carboxylic acid resin (a). Examples of the chain transfer agent include α-methylstyrene linear dimer, n-dodecyl mercaptan, t-dodecyl mercaptan, and n-octyl mercaptan.

[0045] As the polymerization method of the styrene-unsaturated carboxylic acid resin (a), solution polymerization using a polymerization solvent can be adopted. As the polymerization solvent, aromatic solvents such as toluene, ethylbenzene, propylbenzene, butylbenzene, etc. are preferable, and if necessary, a solvent system in which the solubility of the styrene-unsaturated carboxylic acid resin (a) is adjusted by combining polar solvents such as alcohols or ketones, such as monohydric alcohols, may be used.

[0046] In this embodiment, the polymerization solvent is preferably used in the range of 3 to 35 parts by mass, more preferably 5 to 30 parts by mass, relative to 100 parts by mass of all monomers constituting the styrene-unsaturated carboxylic acid resin (a). If the polymerization solvent exceeds 35 parts by mass relative to 100 parts by mass of all monomers, the polymerization rate decreases and the molecular weight of the resulting resin also decreases, so that the mechanical strength of the resin tends to decrease. In addition, if the polymerization solvent is less than 3 parts by mass, it may be difficult to control heat removal during polymerization. Adding the polymerization solvent in a ratio of 3 to 35 parts by mass relative to 100 parts by mass of all monomers is preferred in terms of making the quality uniform and controlling the polymerization temperature.

[0047] When a monohydric alcohol is used as a polymerization solvent, it is preferably added in an amount of 1 to 10% by mass relative to 100% by mass of the total polymerization solvent.

[0048] The apparatus used in the polymerization step for obtaining the styrene-unsaturated carboxylic acid resin (a) according to the present invention is not particularly limited, and may be appropriately selected according to a general polymerization method for styrene-based resins. For example, in the case of bulk polymerization, a polymerization apparatus having one or more completely mixed reactors connected thereto can be used. The devolatilization step is also not particularly limited, and in the case of bulk polymerization, the polymerization is continued until the unreacted monomer is preferably 50 mass% or less, more preferably 40 mass% or less, and in order to remove the volatile matter such as the unreacted monomer, a devolatilization treatment is performed by a known method. For example, a normal devolatilization apparatus such as a flash drum, a twin-screw devolatilizer, a thin film evaporator, an extruder, etc. can be used, but a devolatilization apparatus with a small retention portion is preferred. The temperature of the devolatilization treatment is usually about 190 to 280°C, and more preferably 190 to 260°C from the viewpoint of suppressing decomposition. The pressure of the devolatilization treatment is usually about 0.13 to 4.0 kPa, preferably 0.13 to 3.0 kPa, more preferably 0.13 to 2.0 kPa. As a method for removing volatile matters, for example, a method of removing volatile matters under reduced pressure while heating, or a method of removing volatile matters through an extruder or the like designed for the purpose of removing volatile matters is preferable. <Rubber-modified styrene resin (b)> The rubber-modified styrene-based resin (b) containing an unsaturated carboxylate monomer unit in the present invention (also simply referred to as rubber-modified styrene-based resin (b)) is a copolymer resin obtained by dispersing rubber-like polymer particles in a matrix of a copolymer resin of a styrene-based monomer unit (2) and an unsaturated carboxylate monomer unit, and copolymerizing the styrene-based monomer (2) and the unsaturated carboxylate monomer in the presence of the rubber-like polymer. In this embodiment, when the total of the styrene-unsaturated carboxylic acid-based resin (a) and the rubber-modified styrene-based resin (b) in the styrene-unsaturated carboxylic acid-based resin composition is 100 parts by mass, the content of the rubber-modified styrene-based resin (b) is 5 to 40 parts by mass, more preferably 6 to 35 parts by mass, even more preferably 7 to 30 parts by mass, and even more preferably 8 to 25 parts by mass. If the content of the rubber-modified styrene-based resin (b) is less than 5 parts by mass, the effect of imparting cold impact resistance is reduced, and if it exceeds 40 parts by mass, the heat resistance and transparency are significantly reduced. By setting the content in the above range of 8 to 25 parts by mass, it is possible to obtain a resin composition having an excellent balance between cold impact resistance and heat resistance. <<Styrene-based monomers (2)>> In this embodiment, the styrene monomer (2) to be used for the rubber-modified styrene resin (b) is not particularly limited, as is the styrene monomer (1), and examples thereof include styrene, α-methylstyrene, β-methylstyrene, paramethylstyrene, orthomethylstyrene, metamethylstyrene, chlorostyrene, and bromostyrene. From an industrial viewpoint, styrene and α-methylstyrene are particularly preferred, and styrene is more preferred. As the styrene monomer (2), these may be used alone or in combination of two or more.

[0049] In this embodiment, the content of the styrene-based monomer unit (2) in the rubber-modified styrene-based resin (b) is preferably 40 to 96 mass%, more preferably 45 to 94 mass%, and even more preferably 50 to 92 mass%, based on the entire rubber-modified styrene-based resin (b) (the total amount of the rubber-like polymer and the matrix of the copolymer resin of the styrene-based monomer unit (2) and the unsaturated carboxylate monomer unit). <<Unsaturated carboxylate monomer>> In this embodiment, the unsaturated carboxylic acid ester monomer adjusts the refractive index of the rubber particle dispersion phase formed by graft polymerization onto the dispersed particles of the rubber-like polymer constituting the rubber-modified styrene-based resin (b) and the matrix phase of the copolymer resin, and plays a role in suppressing a decrease in transparency when blended with the styrene-unsaturated carboxylic acid-based resin (a). In the styrene-unsaturated carboxylic acid-based resin (a) of this embodiment, the unsaturated carboxylic acid ester monomer unit is preferably 1 to 55 mass %, more preferably 5 to 40 mass %, based on the entire rubber-modified styrene-based resin (b). <Rubber-like polymer> In this embodiment, the rubber-like polymer in the rubber-modified styrene-based resin (b) may be polybutadiene, polyisoprene, natural rubber, polychloroprene, styrene-butadiene copolymer, acrylonitrile-butadiene copolymer, etc., but from an industrial point of view, polybutadiene and styrene-butadiene copolymer are preferred. As the polybutadiene, high-cis polybutadiene having a high cis content, low-cis polybutadiene having a low cis content, or both of these may be used. The structure of the styrene-butadiene copolymer may be a random structure, a block structure, or a combination of these. These rubber-like polymers may be used alone or in combination of two or more. Saturated rubber obtained by hydrogenating butadiene rubber may also be used.

[0050] In the rubber-like polymer of this embodiment, it is preferable that a polymer having a styrene-based monomer unit (2) and / or an unsaturated carboxylate monomer unit is encapsulated in dispersed particles (rubber-like polymer particles) of the rubber-like polymer. The encapsulation form may be a core-shell type rubber-like polymer having a polymer having a styrene-based monomer unit (2) and / or an unsaturated carboxylate monomer unit as a core and a rubber-like polymer as a shell, or a so-called salami structure type rubber-like polymer having a plurality of domain phases of a polymer having a styrene-based monomer unit (2) and / or an unsaturated carboxylate monomer unit encapsulated in a rubber-like polymer. <Conjugated diene monomer unit content> In this embodiment, the rubber-like polymer is preferably formed from a conjugated diene monomer. In this specification, the conjugated diene monomer unit is a diolefin having a pair of conjugated double bonds among the monomer units constituting the rubber-like polymer, and examples thereof include 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, and 1,3-hexadiene. The content of the rubber-modified styrene-based resin (b) and the styrene-unsaturated carboxylic acid-based resin composition can be measured by the procedure described in the Examples section below or a method equivalent thereto.

[0051] In this embodiment, the content of the conjugated diene monomer unit in the rubber-modified styrene-based resin (b) is preferably 3 to 15 mass %, more preferably 6 to 14 mass %, and even more preferably 7 to 13 mass %, based on the entire rubber-modified styrene-based resin (b).

[0052] When the total amount of the styrene-unsaturated carboxylic acid resin (a) and the rubber-modified styrene-based resin (b) in the styrene-unsaturated carboxylic acid composition according to the present invention is 100 parts by mass, the content of the conjugated diene monomer unit derived from the rubber-modified styrene-based resin (b) or other additives such as MBS is preferably 0.3 to 5.0 parts by mass, more preferably 0.4 to 4.0 parts by mass, and even more preferably 0.5 to 3.0 parts by mass. By making it 0.3 parts by mass or more, the effect of improving cold impact resistance by adding the rubber-modified styrene-based resin (b) can be highly obtained, and by making it 5.0 parts by mass or less, a resin composition with excellent transparency can be obtained. <Rubber particle size> The rubber-like polymer, which is the rubber component in the rubber-modified styrene-based resin (b) in this embodiment, exists as rubber particles in the styrene-unsaturated carboxylic acid-based resin composition. In this case, the rubber particle diameter is preferably 0.3 to 5.0 μm, more preferably 0.4 to 3.0 μm, and even more preferably 0.5 to 1.5 μm. When the rubber particle diameter is 0.3 μm or more, the mechanical strength of the resin composition is good. Also, when the rubber particle diameter is 5.0 μm or less, the transparency and appearance of the resin composition are good. The rubber-modified styrene-based resin (b) is obtained by polymerizing a styrene-based monomer in a reactor equipped with a stirrer in the presence of a rubber-like polymer, and the rubber particle diameter can be adjusted by the rotation speed of the stirrer, the molecular weight of the rubber-like polymer used, and the like. In the present disclosure, the rubber particle diameter is a value measured from a cross-sectional observation image by a transmission electron microscope. <Swelling index> In this embodiment, the swelling index of the toluene insoluble portion of the rubber-modified styrene-based resin (b) is preferably 8.0 to 14.0, and the mass ratio of the toluene insoluble portion to the rubber content in the toluene insoluble portion (toluene insoluble portion / rubber content in the toluene insoluble portion) is preferably 1.5 to 4.0. This swelling index is more preferably 9.0 to 13.0, even more preferably 9.5 to 12.5, and the ratio of the toluene insoluble portion / rubber content in the toluene insoluble portion is more preferably 2.0 to 3.5, even more preferably 2.5 to 3.5. When the swelling index of the toluene insoluble portion of the rubber-modified styrene-based resin (b) is 8.0 to 14.0, and the ratio of the toluene insoluble portion / rubber content in the toluene insoluble portion is 1.5 to 4.0, a resin having excellent mechanical strength is obtained. In this disclosure, the swelling index of the toluene insolubles and the ratio of the toluene insolubles / rubber content in the toluene insolubles are values ​​measured by the procedures described in the Examples section or procedures that will be understood by those skilled in the art to be equivalent thereto.

[0053] In this embodiment, the melt flow rate of the rubber-modified styrene-based resin (b) at 200°C may be preferably 0.5 to 20.0, more preferably 1.0 to 18.0, and even more preferably 2.0 to 16.0. If the melt flow rate is in the range of 0.5 to 20.0, the mixture with the styrene-unsaturated carboxylic acid-based resin (a) is good, and the mechanical strength is also good. In the present disclosure, the melt flow rate is a value measured at 200°C under a load of 49 N in accordance with ISO 1133. <Production method of rubber-modified styrene-based resin (b)> The method for producing the rubber-modified styrene-based resin (b) is not particularly limited, but it can be produced by bulk polymerization (or solution polymerization) in which a styrene-based monomer (2) (and a solvent) is polymerized in the presence of a rubber-like polymer, bulk-suspension polymerization which transitions to suspension polymerization during the reaction, or emulsion graft polymerization in which a styrene-based monomer (2) is polymerized in the presence of a rubber-like polymer latex. In bulk polymerization, the rubber-like polymer can be produced by continuously supplying a mixed solution containing a rubber-like polymer, a styrene-based monomer (2), and, if necessary, an organic solvent, an organic peroxide, and / or a chain transfer agent, to a polymerization apparatus consisting of a complete mixing reactor or a tank reactor and a plurality of tank reactors connected in series.

[0054] <Monohydric alcohols with 16 or more carbon atoms> In a preferred aspect of this embodiment, the styrene-unsaturated carboxylic acid resin composition preferably contains a monohydric alcohol having 16 or more carbon atoms. Alcohols having 15 or less carbon atoms are highly volatile, and the alcohol generates an odor during molding, etc., reducing workability. However, it has been confirmed that by increasing the number of carbon atoms to 16 or more, the volatility is reduced and the unpleasant odor during molding, etc. is suppressed.

[0055] In this embodiment, the monohydric alcohol having 16 or more carbon atoms is contained, which suppresses the formation of gelled matter during molding at around 250°C, and a molded product with excellent appearance can be obtained. The monohydric alcohol is an alcohol having 16 or more carbon atoms and containing one hydroxyl group, and may contain heteroatoms such as oxygen or nitrogen in the carbon chain, and may contain bonds other than single bonds, such as double bonds, triple bonds, ester bonds, and amide bonds in the carbon chain. The number of carbon atoms is preferably 16 or more, more preferably 17 or more, and even more preferably 18 to 50. The monohydric alcohol may be contained in the styrene-unsaturated carboxylic acid resin composition. Therefore, the monohydric alcohol may be present (or added) in the polymerization solution used for polymerizing the styrene-unsaturated carboxylic acid resin (a), so that the monohydric alcohol remains in the resin composition, which is the final product, or may be contained by mixing in an extruder or solvent after polymerization of the styrene-unsaturated carboxylic acid resin (a).

[0056] In this embodiment, when emphasis is placed on processability at around 200°C or on suppression of turbidity, it is preferable to select an alcohol having 5 to 13 carbon atoms, and when emphasis is placed on processability at around 250°C or on suppression of odor, it is preferable to select an alcohol having 16 or more carbon atoms.

[0057] In this embodiment, the boiling point of the monohydric alcohol having 16 or more carbon atoms is preferably 260° C. or higher, more preferably 270° C. or higher, and even more preferably 290° C. or higher. If the boiling point of the alcohol is lower than 260° C., it becomes highly volatile and tends to generate an unpleasant odor during molding, etc.

[0058] The content of the monohydric alcohol having 16 or more carbon atoms in the styrene-unsaturated carboxylic acid resin composition according to the present invention is preferably 0.03 to 1.0 parts by mass, more preferably 0.05 to 0.7 parts by mass, and even more preferably 0.08 to 0.4 parts by mass, when the total of the styrene-unsaturated carboxylic acid resin (a) and the rubber-modified styrene resin (b) is 100 parts by mass. If the content of the monohydric alcohol having 16 or more carbon atoms is less than 0.1 parts by mass, the gel suppression effect during molding at around 250°C decreases. On the other hand, if the content exceeds 1.0 part by mass, the amount remaining in the resin increases, causing an unpleasant odor or a significant decrease in heat resistance, and the effect of increasing heat resistance due to methacrylic acid modification becomes poor.

[0059] The monohydric alcohol having 16 or more carbon atoms is not particularly limited, but examples thereof include 1-hexadecanol, isohexadecanol, 1-octadecanol, 5,7,7-trimethyl-2-(1,3,3-trimethylbutyl)-1-octanol, isooctadecanol, 1-isoisoeicosanol, 8-methyl-2-(4-methylhexyl)-1-decanol, 2-heptyl-1-undecanol, 2-heptyl-4-methyl-1-decanol, 2-(1,5-dimethylhexyl)-(5,9-dimethyl)-1-decanol, and polyoxyethylene alkyl ethers.

[0060] The polyoxyethylene alkyl ether is preferably a compound represented by the following general formula (2).

[0061] [ka]

[0062] (In the above general formula (2), R is an alkyl group having 12 to 20 carbon atoms, and X represents the average number of ethylene oxides added and is an integer of 1 to 15.) <Hindered phenol type antioxidant> As a preferred aspect of this embodiment, the styrene-unsaturated carboxylic acid resin composition preferably contains a hindered phenol type antioxidant. By containing a hindered phenol type antioxidant, yellowing during kneading, extrusion sheet molding, and container molding can be suppressed, and strength reduction due to molecular weight reduction of the rubber dispersion component can be prevented. When the total of the styrene-unsaturated carboxylic acid resin (a) and the rubber-modified styrene resin (b) in the resin composition is taken as 100 parts by mass, the content of the hindered phenol type antioxidant is preferably in the range of 0.001 to 0.5 parts by mass, more preferably 0.003 to 0.5 parts by mass, even more preferably 0.005 to 0.4 parts by mass, and even more preferably 0.01 to 0.2 parts by mass. By making the content 0.001 parts by mass or more, it is effective in suppressing decomposition of the rubber dispersion component, and if it exceeds 0.5 parts by mass, there is a risk of reducing strength due to an increase in the amount of low molecular weight components.

[0063] Examples of the hindered phenol type antioxidant according to the present invention include 2,6-di-t-butyl-p-cresol, 2,6-diphenyl-4-octadecyloxyphenol, distearyl (3,5-di-t-butyl-4-hydroxybenzyl)phosphonate, 1,6-hexamethylenebis[(3,5-di-t-butyl-4-hydroxyphenyl)propionic acid amide], 4,4'-thiobis(6-t-butyl-m-cresol), 2,2'-methylenebis(4-methyl-6-t-butylphenol), 2,2'-methyl- ethylene bis(4-ethyl-6-t-butylphenol), 4,4'-butylidene bis(6-t-butyl m-cresol), 2,2'-ethylidene bis(4,6-di-t-butylphenol), 2,2'-ethylidene bis(4-sec-butyl-6-t-butylphenol), 1,1,3-tris(2-methyl-4-hydroxy-5-t-butylphenyl)butane, 1,3,5-tris(2,6-dimethyl-3-hydroxy-4-t-butylbenzyl)isocyanurate, 1,3,5-tris(3,5-di-t-butyl butyl 4-hydroxybenzyl) isocyanurate, 1,3,5-tris(3,5-di-t-butyl 4-hydroxybenzyl)-2,4,6-trimethylbenzene, 2-t-butyl 4-methyl-6-(2-acryloyloxy-3-t-butyl 5-methylbenzyl)phenol, 3-(3,5-di-t-butyl-4-hydroxyphenyl)stearyl propionate, 2-[1-(2-hydroxy-3,5-di-tert-pentylphenyl)ethyl]-4,6-di-t-pentylphenyl=acrylate, tetramethylphenyl bis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate methyl]methane, 2-t-butyl-6-methyl-4-{3-[(2,4,8,10-tetra-t-butyldibenzo[d,f][1,3,2]dioxaphosphepin-6-yl)oxy]propyl}phenol, thiodiethylene glycol bis[(3,5-di-t-butyl-4-hydroxyphenyl)propionate], 1,6-hexamethylene bis[(3,5-di-t-butyl-4-hydroxyphenyl)propionate], bis[3,3-bis(4-hydroxy-3-t-butylphenyl)butyric acid]glycol ester, bis[2-t-butyl 4-methyl-6-(2-hydroxy-3-t-butyl-5-methylbenzyl)phenyl]terephthalate, 1,3,5-tris[(3,5-di-t-butyl-4-hydroxyphenyl)propionyloxyethyl]isocyanurate, 3,9-bis[1,1-dimethyl-2-{(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxy}ethyl]-2,4,8,10-tetraoxaspiro[5,5]undecane, triethylene glycol bis[(3-t-butyl-4-hydroxy-5-methylphenyl)propionate], etc. These may be used alone or in combination of two or more.

[0064] In this embodiment, the hindered phenol-type antioxidant may be added during polymerization of each resin, or may be additionally kneaded into the styrene-unsaturated carboxylic acid resin (a) and the rubber-modified styrene-based resin (b) containing an unsaturated carboxylic acid ester monomer unit when kneading the resin. <Higher fatty acid surfactants> As a preferred embodiment of the present invention, the styrene-unsaturated carboxylic acid resin composition preferably contains a higher fatty acid. The addition of a higher fatty acid surfactant not only prevents blocking of the sheet, but also contributes to reducing the torque between pellets during kneading of the resin composition by adding the surfactant in an appropriate amount, thereby improving the dispersibility of the rubber particles (rubber-like polymer) derived from the rubber-modified styrene-based resin (b) after kneading the styrene-unsaturated carboxylic acid-based resin (a) and the rubber-modified styrene-based resin (b), and in particular improves the impact strength at -30°C. When the total of the styrene-unsaturated carboxylic acid-based resin (a) and the rubber-modified styrene-based resin (b) is taken as 100 parts by mass, the content of the higher fatty acid surfactant is preferably in the range of 0.002 to 0.1 parts by mass, and by making it 0.002 parts by mass or more, an effect of improving cold impact resistance can be obtained, and by making it 0.1 parts by mass or less, it can be prevented from contributing as a gelling agent for the styrene-unsaturated carboxylic acid-based resin (a).

[0065] The higher fatty acid surfactant may be added during polymerization of each resin, or may be added when the styrene-unsaturated carboxylic acid resin (a) and the rubber-modified styrene-based resin (b) are kneaded together. However, it is particularly preferable to add the surfactant when the styrene-unsaturated carboxylic acid resin (a) and the rubber-modified styrene-based resin (b) are kneaded together.

[0066] The higher fatty acid surfactant is not particularly limited, but examples thereof include stearic acid, calcium stearate, calcium stearate, and ethylene bisstearamide, with ethylene bisstearamide being preferred. <Other ingredients> In addition to the monohydric alcohol, hindered phenol-type antioxidant, or higher fatty acid surfactant, various additives generally used in styrene-based resins may be added to the styrene-unsaturated carboxylic acid-based resin composition of the present embodiment to achieve known effects, and the composition may be made into a styrene-unsaturated carboxylic acid-based resin composition. Examples of such additives include stabilizers, antioxidants, ultraviolet absorbers, lubricants, release agents, plasticizers, antiblocking agents, antistatic agents, antifogging agents, and mineral oils. Reinforcing materials such as styrene-butadiene block copolymers or MBS resins may also be added to the extent that the physical properties are not impaired. There are no particular restrictions on the method of blending, but examples include a method of adding the additives during polymerization and polymerizing them, or a method of mixing the additives in advance in a blender before melt-kneading after polymerization, and then melt-kneading them in an extruder or Banbury mixer.

[0067] In this embodiment, various additives can be added to the styrene-unsaturated carboxylic acid resin composition as described above, but the content of the styrene-unsaturated carboxylic acid resin (a) and the rubber-modified styrene resin (b) in the styrene-unsaturated carboxylic acid resin composition is not particularly limited, but is preferably 90% by mass or more, more preferably 92% by mass or more, and even more preferably 95% by mass or more. In other words, the above other components may be contained in the styrene-unsaturated carboxylic acid resin composition in an amount of less than 10% by mass. [Physical properties of styrene-unsaturated carboxylic acid resin composition] The physical properties of the styrene-unsaturated carboxylic acid resin composition of the present embodiment will be described below.

[0068] In this embodiment, the Vicat softening temperature of the styrene-unsaturated carboxylic acid resin composition is preferably 105° C. or higher, more preferably 115° C. or higher. By setting the Vicat softening temperature at 105° C. or higher, a sheet or container that can be used for cooking in a general microwave oven of about 500 W can be obtained, and by setting the Vicat softening temperature at 115° C. or higher, the sheet or container can withstand cooking in a high-power commercial microwave oven of 1000 W or higher that is installed in a convenience store or the like. The Vicat softening temperature can be measured in accordance with ISO306 under conditions of a load of 50 N and a heating rate of 50° C. / h.

[0069] In this embodiment, the melt flow rate of the styrene-unsaturated carboxylic acid resin composition at 200° C. is preferably in the range of 0.5 to 5.0 g / 10 min, more preferably 1.0 to 3.5 g / 10 min, and even more preferably 1.5 to 2.5 g / 10 min. By making the melt flow rate 0.5 g / 10 min or more, good moldability can be obtained, and by making it 4.5 g / 10 min or less, a resin with excellent strength can be obtained. [Extruded sheet] Another aspect of the present invention provides an extruded sheet formed using the above-mentioned styrene-unsaturated carboxylic acid resin composition of the present invention. The extruded sheet may be either non-foamed or foamed. A commonly known method can be used as a method for producing an extruded sheet. A method for producing a non-foamed extruded sheet can be a method using a single-screw or twin-screw extruder equipped with a T-die and a device for taking up a sheet with a uniaxial or biaxial stretching machine, and a method for producing a foamed extruded sheet can be a method using an extrusion foaming machine equipped with a T-die or circular die. <Foam extrusion sheet> In this embodiment, when forming a foamed extruded sheet, materials that are commonly used for foaming agents and foam nucleating agents during extrusion foaming can be used. Butane, pentane, fluorocarbons, carbon dioxide, water, etc. can be used as the foaming agent, and butane is preferred. Talc, etc. can be used as the foam nucleating agent.

[0070] In this embodiment, the foamed extruded sheet preferably has a thickness of 0.5 mm to 5.0 mm, an apparent density of 50 g / L to 300 g / L, and a basis weight of 80 g / m 2 ~300g / m 2 The foamed extruded sheet of the present invention may be multi-layered, for example, by further laminating a film. The type of film used may be any type commonly used for polystyrene. <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 in terms of rigidity and thermoforming cycle. The uniaxial sheet may be formed only by roll stretching at a normal low magnification, and the biaxially stretched sheet is preferably stretched about 1.3 to 7 times in the machine direction (MD) with a roll and then stretched about 1.3 to 7 times in the perpendicular direction (TD) with a tenter in terms of strength. The non-foamed sheet may be used in a multilayer with a styrene-based resin such as a polystyrene resin other than the styrene-unsaturated carboxylic acid-based resin composition. It may also be used in a multilayer with a resin other than the styrene-based resin. Examples of the resin other than the styrene-based resin include PET resin and nylon resin.

[0071] Another aspect of the present invention provides a molded product formed using the non-foamed extruded sheet or the foamed extruded sheet of the present invention. The foamed extruded sheet or a multi-layer body containing the foamed extruded sheet can be molded, for example, by vacuum forming to produce a container such as a tray. The non-foamed extruded sheet can also be molded, for example, by vacuum forming to produce a lid for a lunch box or a container for storing side dishes. EXAMPLES

[0072] The present invention will now be described in detail with reference to examples and comparative examples, but the present invention is not limited to these examples. The resins and extruded sheets in the examples and comparative examples were analyzed and evaluated as follows. [Evaluation of properties of each resin and resin composition] (1) Measurement of weight average molecular weight The weight average molecular weight (Mw) of each resin and resin composition was measured by gel permeation chromatography (GPC) under the following conditions.

[0073] Measuring equipment: Tosoh HLC-8220 Separation column: Two Tosoh TSK gel Super HZM-H (inner diameter 4.6 mm) connected in series Guard column: Tosoh TSK guard column Super HZ-H Measurement solvent: tetrahydrofuran (THF) Sample concentration: 5 mg of the measurement sample was dissolved in 10 mL of solvent and filtered through a 0.45 μm filter.

[0074] Injection volume: 10μL Measurement temperature: 40℃ Flow rate: 0.35mL / min Detector: Ultraviolet absorption detector (Tosoh UV-8020, wavelength 254 nm) The calibration curve was created using 11 types of TSK standard polystyrene (F-850, F-450, F-128, F-80, F-40, F-20, F-10, F-4, F-2, F-1, A-5000) manufactured by Tosoh Corporation. The calibration curve was created using a linear approximation equation. (2) Measurement of Melt Mass Flow Rate (MFR) The melt mass flow rate (g / 10 min) of each resin and resin composition was measured at 200° C. and a load of 49 N in accordance with ISO1133. (3) Measurement of Vicat softening temperature The Vicat softening temperature of each resin and resin composition was measured in accordance with ISO306. The load was 50N and the heating rate was 50℃ / h. Sheet moldings using materials with a Vicat softening temperature of over 105℃ have excellent dimensional stability at temperatures (100℃ or higher) that are assumed to be heated in a microwave oven. In particular, materials with a Vicat softening temperature of over 115℃ tended to show almost no dimensional change at practical temperatures. (4) Measurement of alcohol content in styrene-unsaturated carboxylic acid resin composition The content of monohydric alcohols having 16 or more carbon atoms when the total of the styrene-unsaturated carboxylic acid resin (a) and the rubber-modified styrene resin (b) was taken as 100 parts by mass was measured using gas chromatography under the following conditions. Sample preparation: 2.0 g of resin was dissolved in 20 mL of methyl ethyl ketone, and then 5 mL of hexane containing a standard substance (p-diethylbenzene) was added to reprecipitate the polymer component, and the supernatant was collected and used as the measurement solution.

[0075] Measurement equipment: Agilent 6850 series GC system Detector: FID Column: HP-1 (100% dimethylpolysiloxane) 30m, Film thickness: 0.25μm, 0.32mmφ Injection volume: 1 μL (splitless) Column temperature: 40°C for 2 minutes → Raise to 320°C at 20°C / min → Hold at 320℃ for 15 minutes Inlet temperature: 250℃ Detector temperature: 280℃ Carrier gas: Helium (5) Determination of conjugated diene monomer unit content The content of conjugated diene monomer units was measured by pyrolysis GC so as to satisfy the following conditions.

[0076] Sample preparation: The styrene-based resin composition was dissolved in chloroform at 5% by mass, and 20 μl of the solution was applied to Pyrofoil and dried in vacuum at 80° C. for 24 hours.

[0077] Measurement conditions Py-GC Equipment: Japan Analytical Industry Co., Ltd. Curie point injector Pyrofoil temperature: 590℃ High frequency irradiation time: 10 seconds GC Equipment: Agilent Technologies HP-GC-6890 Column: HP-5MS 30m, film thickness 0.25mm, 0.25mmφ Column temperature: held at 50°C for 5 minutes, heated at 10°C / min, heated from 100°C at 70°C / min, and held at 300°C for 10 minutes.

[0078] Inlet temperature: 300℃ Detector temperature: 300℃ Split ratio: 1 / 20 Carrier gas: Helium Detection method: MSD (6) Average particle size of rubber particles in rubber-modified styrene-based resin (b) The average particle size (μm) of rubber particles in the rubber-modified polystyrene resin (b) (so-called HIPS resin) was determined by observing the cross-section of 200 rubber-like elastomer particles using a transmission electron microscope, using the following formula (2): Average particle diameter=Σ(ni×Di 4 ) / Σ(ni×Di 3 ) {In the above formula (2), ni is the number of rubber-like elastomer particles having a particle diameter Di, and Di is the average value of the major axis and minor axis of the rubber-like elastomer particles.} It was calculated by: (7) Measurement of swelling index of toluene insoluble matter of rubber-modified styrene-based resin (b) 1 g of rubber-modified styrene-based resin (b) was weighed out in a precipitation tube (W1), 20 mL of toluene was added, and the mixture was shaken at 23°C for 2 hours, and then centrifuged at 10°C or less and 20,000 rpm for 60 minutes in a centrifuge (Hitachi, Ltd. himac, CR-20 (rotor: R20A2)). The precipitation tube was slowly tilted at about 45 degrees, and the supernatant liquid was decanted and removed. The mass of the insoluble matter containing toluene was weighed out (W2), and the mixture was vacuum-dried at 160°C and 3 kPa or less for 1 hour. The dried toluene-insoluble matter was cooled to room temperature in a desiccator, and then the mass was weighed out (W3).

[0079] The swelling index of the toluene insoluble matter and the toluene insoluble matter were calculated according to the following formulas.

[0080] Toluene insolubles (mass%) = ((W3) / (W1)) x 100 Swelling index of toluene insoluble matter = (W2 / W3) [Evaluation of sheet molding properties] (8) Appearance assessment of non-foamed extruded sheets A styrene-unsaturated carboxylic acid resin composition was used to extrude a sheet using a 30 mmφ short-axis sheet extruder for three consecutive hours, and then five sheets measuring 10 cm x 20 cm were cut out from the 0.3 mm thick sheet. The number of gels and air bubbles, which were foreign matter with an average diameter of (long axis + short axis) / 2 of 0.5 mm or more on the surfaces of the five sheets, was counted, and the appearance was judged using the following method. ○: Gel or bubbles count is 2 or less △: Gel, number of bubbles: 3 to 9 points ×: Gel, 10 or more bubbles (9) Measurement of film impact of biaxially oriented sheet A press plate having a thickness of 1.2 to 1.6 mm was prepared using a press molding machine using a styrene-unsaturated carboxylic acid resin composition. A sheet having a size of 10 cm x 10 cm was cut out from the prepared press plate. The cut out sheet was subjected to simultaneous biaxial stretching under the following conditions using a biaxial stretching device (EX6-S1) manufactured by Toyo Seiki Co., Ltd., to prepare a biaxially stretched sheet having a thickness of approximately 0.2 mm.

[0081] Stretching temperature: Vicat softening temperature of styrene-unsaturated carboxylic acid resin composition + 20 to 30°C, Stretching speed: 170% Stretching ratio: 2.5x The obtained sheet was cut into a size of 8 cm x 8 cm, and the film impact was measured using a film impact tester (No. 195) manufactured by Toyo Seiki Seisakusho Co., Ltd., and the n8 average was recorded as the value. (10) Heat resistance of biaxially oriented sheets The biaxially oriented sheet was placed in an oven set at 110° C. for 60 minutes, after which the deformation of the container was visually observed, and the heat resistance was evaluated based on the thermal deformation as follows.

[0082] ◎: Dimensional change of 1% or less ○: Dimensional change: 1% to 3% ×: Dimensional deformation 3% or more (11) Biaxially oriented sheet drop weight impact strength at -30℃ The axially stretched sheet was cooled for 2 hours or more in a refrigerator set at -30°C, and then the drop weight impact strength was immediately measured using a DuPont impact tester (No. 451) manufactured by Toyo Seiki Co., Ltd. The mass of the falling weight was 0.025 kg, the radius of the tip of the impact center was 6.3 mm, and the radius of the impact center receiving stand was 9.4 mm. The drop weight impact strength was calculated as the 50% fracture value, calculated as (mass of the falling weight 0.025 kg) x (height in cm).

[0083] In addition, when a stretched sheet molded product of a styrene-unsaturated carboxylic acid resin composition having a falling weight impact strength of 7.0 or more at -30°C is molded into a lid material, the lid material showed a tendency to crack less during frozen transportation at around -30°C. (12) Measuring the haze of the sheet The haze of the stretched sheet was measured at 0.2 mm using a haze meter (NDH-2000) manufactured by Nippon Denshoku Industries Co., Ltd., and the n3 average was used as the haze value. [Foam extrusion properties] (13) Measurement of the stiffness of tray containers at -30℃ After cooling the tray container for 2 hours or more in a freezer set at -30°C, the flexure of the tray container molded using the styrene-unsaturated carboxylic acid resin composition was measured by the method shown in Figure 1. More specifically, the tray container 1, which was vacuum molded from a foamed extrusion sheet expanded 7.3 times, was compressed in the TD direction with a crosshead 2 at a compression speed of 5 mm / min, and the flexure (N) of the tray container 1 was measured. The size of the tray container 1 was 10 cm long, 15 cm wide, and 2 cm deep. The tray container 1 was compressed from the lateral side and the maximum load was taken as the flexure. The styrene-unsaturated carboxylic acid resin composition showing a flexure strength of 15 N or more at -30°C showed a tendency for the tray container to crack less during frozen transportation at about -30°C. [Production examples of resins and resin compositions] Specific production examples of the styrene-unsaturated carboxylic acid resin (a) and the rubber-modified styrene resin (b) will be described below. <Production Example of Styrene-Unsaturated Carboxylic Acid Resin (a)> <<Preparation of resin a-1>> A polymerization raw material composition liquid consisting of 82.4 parts by mass of styrene, 2.6 parts by mass of methacrylic acid, 15.0 parts by mass of ethylbenzene, and 0.025 parts by mass of 1,1-bis(t-butylperoxy)cyclohexane was fed at a rate of 0.8 liters / hour to a complete mixing type reactor having a capacity of 3.6 liters, and then continuously fed to a volatilizing device connected to a single screw extruder for removing volatile components such as unreacted monomers and polymerization solvent. The polymerization temperature of the complete mixing reactor was set to 125°C. The temperature of the single screw extruder was set to 200 to 250°C, and the pressure was set to 10 torr, to volatilize volatile components such as unreacted monomers and polymerization solvent. The volatilized volatile components were condensed in a condenser through which a refrigerant of -5°C was passed, and were recovered as an unreacted liquid, and a styrene-unsaturated carboxylic acid resin (a-1) was recovered as a resin pellet. The physical properties of the resin a-1 obtained by the above-mentioned analysis method are shown in Table 1 below. <<Preparation of resin a-2>> Resin a-2 was prepared using the same procedure as for Resin a-1 above, with the feed amount of methacrylic acid being adjusted in part, and the raw material composition shown in Table 1. The physical properties of Resin a-2 are as shown in Table 1. <<Preparation of resins a-3, a-5, and a-6>> Methyl methacrylate was added as a monomer, and resins a-3, a-5, and a-6 were prepared using the same procedure as above and the raw material compositions shown in Table 1. The physical properties of these resins are shown in Table 1 below. <<Preparation of resin a-4>> Further, n-butyl acrylate was added as a monomer, and resin a-4 was prepared using the same procedure as above with the raw material composition shown in Table 1. The physical properties of resin a-4 are shown in Table 1. <<Preparation of resin a-7>> Methacrylic acid (2-ethylhexyl) was further added as a monomer to prepare resin a-7 by the same procedure as a-2. The physical properties of resin a-7 are shown in Table 1. <<Preparation of resin a-8>> Methacrylic acid (n-octyl) was further added as a monomer to prepare resin a-8 in the same manner as resin a-2. The physical properties of resin a-8 are shown in Table 1. <<Preparation of resin a-9>> Resin a-9 was prepared as a styrene homopolymer by the same procedure as above, using only styrene as a monomer. The physical properties of resin a-9 are shown in Table 1.

[0084] [Table 1]

[0085] <Production example of rubber modified styrene resin (b)> <<Preparation of resin b-1>> A rubber-modified styrene-based resin b-1 (hereinafter, resin b-1) was produced using a polymerization apparatus in which three laminar flow reactors (1.5 liters) equipped with stirrers were connected in series and followed by a two-stage vented extruder. 71.3 parts by mass of styrene, 7.9 parts by mass of methyl methacrylate, 10.0 parts by mass of ethylbenzene, 10.8 parts by mass of Asahi Kasei Corporation's Asaprene 625A, a styrene-butadiene copolymer, as a rubber component, and 0.02 parts by mass of 1,1-bis(t-butylperoxy)cyclohexane were charged into a raw material tank equipped with a stirrer, and after dissolving the rubber component with a stirrer, this raw material solution was supplied to the reactor at a volume of 0.75 liters / hr, and polymerization was performed at a temperature of 110 to 120 ° C. in the first stage reactor, 120 to 130 ° C. in the second stage reactor, and 140 to 150 ° C. in the third stage reactor. The extruder temperature was 210-240°C, the degree of vacuum was 3 kPa, and the total solid content in the polymerization liquid discharged from the final reactor was 70.1% by mass. The rubber particle size was controlled by adjusting the rotation speed of the stirrer of the first-stage laminar flow reactor to 150 rpm. The composition and properties of the obtained rubber-modified styrene-based resin b-1 (hereinafter referred to as resin b-1) are shown in Table 2. <<Preparation of resin b-2>> Using styrene and (n-butyl) acrylate as monomers and Asahi Kasei Corporation's Asaprene 625A, a styrene-butadiene copolymer, as the rubber component, resin b-2 was prepared using the same procedure as above, with a styrene-(n-butyl) acrylate copolymer as the matrix component. The composition and properties of the obtained resin b-2 are shown in Table 2. <<Preparation of resin b-3>> Using styrene and methyl methacrylate as monomers and Asahi Kasei Corporation's Asaprene 625A, a styrene-butadiene copolymer, as the rubber component, resin b-3 was prepared using the same procedure as above, with a styrene-methyl methacrylate copolymer as the matrix component. The composition and properties of the obtained resin b-3 are shown in Table 2. <<Preparation of resin b-4>> Using styrene, methyl methacrylate, and n-butyl acrylate as monomers and Asahi Kasei Corporation's Asaprene 625A, a styrene-butadiene copolymer, as the rubber component, resin b-4 was prepared in the same manner as above, with a styrene-methyl methacrylate-(n-butyl)acrylate copolymer as the matrix component. The composition and properties of the obtained resin b-4 are shown in Table 2. <<Preparation of resin b-5>> For comparison, resin b-5 having a styrene homopolymer matrix was prepared in the same manner as above using the composition shown in Table 2.

[0086] [Table 2]

[0087] <Production Example of Styrene-Unsaturated Carboxylic Acid Resin Composition> The detailed method for producing the styrene-unsaturated carboxylic acid resin composition will be described below. [Example 1] 90 parts by mass of the obtained styrene-unsaturated carboxylic acid resin (resin a-1), 10 parts by mass of rubber-modified styrene resin (resin b-3), 0.16 parts by mass of monohydric alcohol having 18 carbon atoms (Nissan Chemical Industries, Ltd. FO-180), 0.04 parts by mass of Irganox 1076 manufactured by BASF Japan Ltd. as a hindered phenol type antioxidant, and 0.008 parts by mass of ethylene bisstearic acid amide were kneaded at 220 ° C. and 80 rpm using a 30 mm φ twin-screw extruder, and then pelletized to obtain a pellet-shaped styrene-unsaturated carboxylic acid resin composition. The contents of each component after extrusion and the various evaluation results after sheet molding are shown in Table 3-1 below. [Examples 2 to 15] Resin compositions were obtained in the same manner as in Example 1, except that the formulation was changed as shown in Tables 3-1 and 3-2. [Comparative Example 1] A resin composition was obtained in the same manner as in Example 1, except that the formulation was changed as shown in Table 4. When a-7, a styrene homopolymer, was used as resin (a), the heat resistance was low and the haze of the sheet was large. [Comparative Example 2] A resin composition was obtained in the same manner as in Example 1, except that the formulation was changed as shown in Table 4. When resin b-5, which contains a styrene homopolymer as a matrix component as a rubber-modified styrene-based resin, was used, the haze of the sheet increased. [Comparative Example 3] A resin composition was obtained in the same manner as in Example 1, except that the composition was changed as shown in Table 4. When the amount of the rubber-modified styrene-based resin (b) was small, the strength of the sheet molding decreased. [Comparative Example 4] A resin composition was obtained in the same manner as in Example 1, except that the formulation was changed as shown in Table 4. When the amount of the rubber-modified styrene-based resin (b) was too large, the heat resistance decreased and the haze of the sheet increased.

[0088] [Table 3-1]

[0089] [Table 3-2]

[0090] [Table 4] [Industrial Applicability]

[0091] The styrene-unsaturated carboxylic acid resin composition obtained by the present invention has excellent heat resistance, transparency, and cold impact resistance. Therefore, the styrene-unsaturated carboxylic acid resin composition of the present invention can be widely used for non-foamed or foamed sheets by extrusion molding, food packaging containers using them, or molded products by injection molding (electrical product parts, toys, daily necessities, various industrial parts), etc., and is particularly useful as a packaging material for refrigerated transport, and plays a major role in the industrial world.

Claims

1. A styrene-unsaturated carboxylic acid resin (a) containing a styrene-based monomer unit (1) and an unsaturated carboxylic acid monomer unit, or containing a styrene-based monomer unit (1), an unsaturated carboxylic acid monomer unit, and an unsaturated carboxylic acid ester monomer unit; a rubber-modified styrene-based resin (b) obtained by dispersing rubber-like polymer particles in a matrix phase of a copolymer resin containing styrene-based monomer units (2) and unsaturated carboxylic acid ester monomer units, and copolymerizing the styrene-based monomer units (2) and unsaturated carboxylic acid ester monomer units in the presence of the rubber polymer particles, the content of the styrene-unsaturated carboxylic acid resin (a) is 60 to 95 parts by mass, and the content of the rubber-modified styrene-based resin (b) is 5 to 40 parts by mass, when the total amount of the styrene-unsaturated carboxylic acid resin (a) and the rubber-modified styrene-based resin (b) is 100 parts by mass; the content of the conjugated diene monomer unit constituting the rubber-like polymer is 3 to 15 mass% based on the total mass of the rubber-modified styrene-based resin (b); a polymer resin having the styrene-based monomer unit (2) and the unsaturated carboxylate monomer unit is encapsulated in the rubber-like polymer particle, and the polymer resin having the styrene-based monomer unit (2) and the unsaturated carboxylate monomer unit is grafted onto the rubber-like polymer, the content of the styrene-based monomer unit (1) in the styrene-unsaturated carboxylic acid-based resin (a) is 60 to 98 mass%, the content of the unsaturated carboxylic acid monomer unit is 2 to 40 mass%, and the content of the unsaturated carboxylic acid ester monomer unit is 0 to 20 mass%, based on the entirety of the styrene-unsaturated carboxylic acid-based resin (a); the unsaturated carboxylic acid monomer unit is a monomer unit of either acrylic acid or methacrylic acid, The unsaturated carboxylic acid ester monomer unit is represented by the following general formula (1): 【Chemistry 1】 (In the above general formula (1), R １ represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms; R ２ represents an ester substituent and represents an alkyl group having 1 to 12 carbon atoms; A styrene-unsaturated carboxylic acid resin composition, wherein the content of the unsaturated carboxylic acid ester monomer unit in the rubber-modified styrene-based resin (b) is 1 to 55 mass % based on the total mass of the rubber-modified styrene-based resin (b).

2. the styrene-unsaturated carboxylic acid resin (a) comprises a styrene monomer unit (1), an unsaturated carboxylic acid monomer unit, and a (meth)acrylic acid ester monomer unit; The styrene-unsaturated carboxylic acid resin composition according to claim 1, wherein the content of the styrene-based monomer unit (1) is 60 to 98 mass%, the content of the unsaturated carboxylic acid monomer unit is 2 to 20 mass%, and the content of the unsaturated carboxylic acid ester monomer unit is 0 to 20 mass%, based on the entire styrene-unsaturated carboxylic acid resin (a).

3. The styrene-unsaturated carboxylic acid resin composition according to claim 2, wherein the number of carbon atoms of the ester substituent of the (meth)acrylic acid ester monomer unit contained in the styrene-unsaturated carboxylic acid resin (a) is 10 or less.

4. 4. The styrene-unsaturated carboxylic acid resin composition according to claim 1, having a melt mass flow rate of 0.5 to 5.0 g / 10 min.

5. 5. The styrene-unsaturated carboxylic acid resin composition according to claim 1, which has a Vicat softening temperature of 105° C. or higher.

6. A styrene-unsaturated carboxylic acid-based composition further having a monohydric alcohol having 16 or more carbon atoms, The styrene-unsaturated carboxylic acid resin composition according to any one of claims 1 to 5, wherein the styrene-unsaturated carboxylic acid resin (a) and the rubber-modified styrene-based resin (b) are combined to produce a styrene-unsaturated carboxylic acid resin having 16 or more carbon atoms in an amount of 0.1 to 1.0 part by mass, based on 100 parts by mass of the total of the styrene-unsaturated carboxylic acid resin (a) and the rubber-modified styrene-based resin (b).

7. A styrene-unsaturated carboxylic acid composition further comprising an ethylene bisamide compound, The styrene-unsaturated carboxylic acid resin composition according to any one of claims 1 to 6, wherein the ethylene bisamide compound is contained in an amount of 0.001 to 0.05 parts by mass when the total amount of the styrene-unsaturated carboxylic acid resin (a) and the rubber-modified styrene-based resin (b) is 100 parts by mass.

8. A styrene-unsaturated carboxylic acid-based composition further comprising a hindered phenolic antioxidant, The styrene-unsaturated carboxylic acid resin composition according to any one of claims 1 to 7, wherein the hindered phenol antioxidant is contained in an amount of 0.002 to 0.1 parts by mass when the total amount of the styrene-unsaturated carboxylic acid resin (a) and the rubber-modified styrene resin (b) is 100 parts by mass.

9. The rubber-modified styrene-based resin (b) comprises a rubber-like polymer containing a conjugated diene monomer unit, a matrix resin containing the styrene-based monomer units (2) and the unsaturated carboxylic acid ester monomer units in which the rubber-like polymer is dispersed, The styrene-unsaturated carboxylic acid resin composition according to any one of claims 1 to 8, wherein the content of the conjugated diene monomer unit is 0.3 to 5.0 parts by mass when the total of the styrene-unsaturated carboxylic acid resin (a) and the rubber-modified styrene-based resin (b) is 100 parts by mass.

10. The styrene-unsaturated carboxylic acid resin composition according to claim 9, wherein the weight average molecular weight (Mw) of a mixed resin of the styrene-unsaturated carboxylic acid resin (a) and the matrix resin of the rubber-modified styrene-based resin (b) is 100,000 to 350,000.

11. A uniaxially and biaxially oriented non-foamed extruded sheet comprising the styrene-unsaturated carboxylic acid resin composition according to any one of claims 1 to 10.

12. A foamed extruded sheet comprising the styrene-unsaturated carboxylic acid resin composition according to any one of claims 1 to 10.

13. A molded product formed using the non-foamed extruded sheet according to claim 11 or the foamed extruded sheet according to claim 12.

14. A lid material for a lunch box container that can be cooked in a microwave oven, formed by secondary molding of the non-foamed extruded sheet according to claim 11.

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