Styrenic resin composition sheet

Abstract

To provide a styrenic resin composition sheet which reduces environmental loads, is excellent in oil resistance and heat insulation property, and has less odor and coloration.SOLUTION: A styrenic resin composition sheet contains 70.0-97.0 mass% of a styrenic resin (A) and 3-30 mass% of a cellulose-based polysaccharide (B) having a lignin content of 10 mass% or less, and has a contact angle with water on the surface of 50° to 105° .SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a styrene-based resin composition sheet. [Background technology]

[0002] Styrenic resins are used in a wide range of applications due to their excellent moldability, dimensional stability, and transparency. Biomass materials are also attracting attention from the perspective of environmental protection, and composite materials made from resin materials and naturally derived organic fillers or biopolymers are being investigated. For example, Patent Documents 1 and 2 disclose styrene-based composite resin compositions consisting of a styrene-based resin and a cellulose-based material, while Patent Document 3 discloses a composition consisting of a styrene-based resin and modified nanocellulose (hereinafter also referred to as CNF). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 7-173352 [Patent Document 2] Japanese Patent Application Publication No. 8-231795 [Patent Document 3] Japanese Patent Application Laid-Open No. 2016-176052 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the technologies of Patent Documents 1 and 2, wood flour or pulp is used as the cellulose-based material, but the applications and effects of the cellulose-based material as a sheet molding are not considered at all, and the sheet molding contains a large amount of lignin, which causes a strong odor and discoloration, making it difficult to use. Furthermore, the ABS resin used in the technology of Patent Document 3 is expensive, and the molding temperature is somewhat high, which causes problems such as partial carbonization of the cellulose-based material depending on the molding conditions or the unmodified cellulose material.

[0005] Therefore, the present disclosure aims to provide a styrene-based resin composition sheet that reduces the environmental load, has excellent oil resistance and heat insulation properties, and is less odorous and discolored. [Means for solving the problem]

[0006] In view of the above problems, the present inventors have conducted extensive research and experiments, and as a result have found that the above problems can be solved by using a styrene-based resin composition sheet characterized by containing 70 to 97 mass % of a styrene-based resin (A) and 3 to 30 mass % of a cellulose-based polysaccharide (B) having a lignin content of 10 mass % or less, thereby completing the present invention. That is, the present invention is as follows [1] to [5].

[0007] [1] The present disclosure provides a styrene-based resin composition sheet comprising 70.0 to 97.0 mass% of a styrene-based resin (A) and 3 to 30 mass% of a cellulose-based polysaccharide (B) having a lignin content of 10 mass% or less, and having a contact angle with water on the surface in the range of 50° to 105°. [2] In this embodiment, the amount of hemicellulose in the cellulose polysaccharide (B) is preferably 1% by mass or more. [3] In this embodiment, it is preferable that the styrene-based resin composition further contains 0.5 to 10.0 parts by mass of a dispersant (C) based on 100 parts by mass of the total amount of the styrene-based resin composition. [4] In this embodiment, the dispersant (C) is preferably one or more compounds selected from the group consisting of fatty acid ester compounds, polyethylene glycol compounds, terpene compounds, and rosin compounds. [5] In this embodiment, it is preferable that the styrene-based resin composition further contains 0.5 to 10.0 parts by mass of a compatibilizer (D) based on 100 parts by mass of the total amount of the styrene-based resin composition. [6] In this embodiment, the compatibilizer (D) is preferably a maleic acid-modified styrene-based rubbery polymer. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a styrene resin composition sheet which reduces the environmental load, has excellent oil resistance and heat insulation properties, and is less odorous and discolored. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 shows an example of a container using a styrene-based resin composition sheet of the present embodiment. [Figure 2] FIG. 2 shows an example of a method for producing a container using a styrene-based resin composition sheet of this embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] The following describes in detail an embodiment of the present invention (hereinafter referred to as "the present embodiment"); however, the present invention is not limited to the following description and can be implemented in various modifications within the scope of its gist. [Styrene-based resin composition sheet] The styrene-based resin composition sheet according to this embodiment contains 70.0 to 97.0 mass% of a styrene-based resin (A) and 3 to 30 mass% of a cellulose-based polysaccharide (B) having a lignin content of 10 mass% or less. In other words, the styrene-based resin composition sheet only needs to contain predetermined amounts of the styrene-based resin (A) and the cellulose-based polysaccharide (B). Therefore, the styrene-based resin composition containing the styrene-based resin (A) and the cellulose-based polysaccharide (B) may be used as the main raw material, or the styrene-based resin (A) and the cellulose-based polysaccharide (B) may be separately blended and directly formed into a sheet without passing through the styrene-based resin composition. Furthermore, the styrene-based resin composition sheet according to this embodiment may further contain a dispersant (C), a compatibilizer (D), and optional additional components, as necessary. More specifically, the styrene-based resin composition sheet according to this embodiment contains 70.0 to 97.0 mass% of a styrene-based resin (A), 3 to 30 mass% of a cellulose-based polysaccharide (B) having a lignin content of 10 mass% or less, and 0.5 to 10 mass% of a dispersant (C) and 0.5 to 10 mass% of a compatibilizer (D), which are added as necessary, and 0 to 5 mass% of optional additional components. In this specification, the term "main component" refers to the component that accounts for the largest mass ratio in the materials constituting the sheet, and is preferably 55% by mass or more and 100% by mass or less, more preferably 70% by mass or more and 100% by mass or less, and even more preferably 90% by mass or more and 100% by mass or less. The shape or thickness of the styrene-based resin composition sheet in this embodiment is not particularly limited, and the shape and thickness can be appropriately changed to match the desired size depending on the purpose. For example, the average thickness of the styrene-based resin composition sheet in this embodiment is preferably 0.1 to 2 mm, more preferably 0.2 to 1 mm, and even more preferably 0.3 to 0.8 mm. If the average thickness is less than 0.1 mm, the sheet will lack rigidity when molded into a food container, and if the average thickness is greater than 2 mm, the productivity of vacuum molding will decrease. In this specification, the average thickness of the styrene-based resin composition sheet is calculated using a thickness meter.

[0011] The surface of the styrene-based resin composition sheet in this embodiment may be coated with a resin film, such as a styrene-based resin (A), a styrene-based resin other than the styrene-based resin (A), or a polyolefin-based resin, for smoothness or design. The resin film may be laminated on one or both sides of the styrene-based resin composition sheet. The styrene-based resin (A) described below can be used as the styrene-based resin (A). Polyolefin-based resins include polyethylene, polypropylene, polyvinyl acetate, and polyvinyl alcohol, and these may be copolymers. In particular, laminating a polypropylene resin layer on at least one surface of the styrene-based resin composition sheet in this embodiment is preferred from the viewpoint of oil resistance. Examples of methods for laminating the resin film include co-extrusion using an extruder and film lamination. The styrene-based resin composition sheet that can be used in the present invention has excellent adhesion to polyolefin-based resins and is less likely to peel off when heated, etc.

[0012] If necessary, the surface of the styrene-based resin composition sheet of this embodiment may be subjected to a surface treatment. Examples of such surface treatments include degreasing, UV ozone treatment, blasting, polishing, plasma treatment, corona discharge treatment, laser treatment, etching, and flame treatment. This allows the surface condition of the styrene-based resin composition sheet to be adjusted. Specifically, the surface treatment makes it easier to adjust the contact angle with water on the surface of the styrene-based resin composition sheet of this embodiment to a range of 50° to 105°. Degreasing is a method of removing surface dirt such as oil and grease by dissolving it in organic solvents such as acetone or hexane. UV ozone treatment is a method of cleaning or modifying surfaces using short-wavelength ultraviolet light emitted from a low-pressure mercury lamp and the ozone (O3) generated by the ultraviolet light. Blast treatment involves spraying various fine particles onto a surface, and includes wet blasting, shot blasting, and sandblasting. Polishing treatments include buffing with an abrasive cloth, roll polishing with abrasive paper (sandpaper), and electrolytic polishing. Plasma treatment is a method of exciting and functionalizing surface molecules by irradiating a surface with a plasma beam generated using a high-voltage power supply and a rod. Corona discharge treatment is primarily used for surface modification of resins and other materials. It involves the formation of polar groups on the resin surface using radicals generated by electrons emitted from an electrode cleaving the polymer main chain or side chain on the resin surface. Laser treatment is a method of roughening a surface by rapidly heating and cooling the surface using laser irradiation. The etching treatment may be a chemical etching treatment such as an alkali method, a phosphoric acid-sulfuric acid method, a fluoride method, a chromic acid-sulfuric acid method, or an iron chloride method. The flame treatment is a method in which a mixed gas of combustion gas and air is burned to convert the oxygen in the air into plasma, and then the plasmatized oxygen is applied to the surface to make the surface hydrophilic.

[0013] When the contact angle with water on the surface of the styrene-based resin composition sheet of the present embodiment is in the range of 50° to 105°, when the sheet is used as a material to be wound around the outermost circumference of various rolls, ink, adhesive components, metal powder, various resins, etc. may be less likely to adhere to the rolls. The water contact angle on the surface of the styrene-based resin composition sheet of this embodiment is preferably in the range of 50° to 105°, more preferably in the range of 75° to 100°, and even more preferably in the range of 80° to 95°. In order to set the water contact angle in the above range, lamination with the aforementioned resin film or surface treatment may be performed.

[0014] In this embodiment, the following six methods (a) to (f) can be mentioned as methods for controlling the contact angle with water on the surface of the styrene-based resin composition sheet to within the range of 50° to 105°. (a) A styrene-based resin (A) (hereinafter also referred to as component (A)) and a cellulose-based polysaccharide (B) (hereinafter also referred to as component (B)) having a lignin content of 10 mass % or less are blended in predetermined amounts. Specifically, by blending 70.0 to 97.0 mass % of component (A) and 3 to 30 mass % of component (B), it is easy to ensure a balance between the hydrophobic and hydrophilic materials in the styrene-based resin composition sheet. (b) It is preferable to blend predetermined amounts of optional dispersant (C) (hereinafter also referred to as component (C)) and compatibilizer (D) (hereinafter also referred to as component (D)). Specifically, blending 0.5 to 10 mass% of component (C) and 0.5 to 10 mass% of component (D) improves the dispersibility of each component constituting the styrene-based resin composition sheet and improves surface smoothness. (c) As an optional additive component, a lubricant may be blended into the styrene-based resin composition sheet in an amount of about 0.05 to 5 mass % relative to the total amount of the sheet, thereby improving the dispersibility of each component constituting the styrene-based resin composition sheet and improving the surface smoothness. The lubricant is not particularly limited, and known lubricants can be used. Examples include fatty acids, fatty acid esters, fatty acid amides, and mixtures thereof. Examples of the fatty acids include lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, behenic acid, erucic acid, and elaidic acid, with stearic acid, myristic acid, and palmitic acid being preferred. The fatty acids may be contained in the form of a salt, such as a metal salt. Examples of the fatty acid esters include esters of the various fatty acids mentioned above, such as butyl myristate, butyl palmitate, butyl stearate, neopentyl glycol dioleate, sorbitan monostearate, sorbitan distearate, sorbitan tristearate, oleyl oleate, isocetyl stearate, isotridecyl stearate, octyl stearate, isooctyl stearate, amyl stearate, and butoxyethyl stearate. Examples of the fatty acid amides include amides of various fatty acids, such as lauric acid amide, myristic acid amide, palmitic acid amide, and stearic acid amide. (d) It is preferable that the surface of the styrene-based resin composition sheet of the present embodiment is subjected to a surface treatment, as described above, and the surface treatment is preferably one or more treatments selected from the group consisting of degreasing treatment, UV ozone treatment, blasting treatment, polishing treatment, plasma treatment, corona discharge treatment, laser treatment, etching treatment, and flame treatment. (e) It is preferable to form a laminate by covering the surface of the styrene resin composition sheet with a styrene resin (A) or a polypropylene resin layer (average thickness 2 to 200 μm). This allows the surface of the styrene resin composition sheet to be coated with a hydrophobic material, making it possible to easily control the contact angle with water to within the range of 50° to 105°. The method for laminating the polypropylene resin layer is preferably the method described above or shown in the Examples. (f) It is preferable that the heating temperature during (extrusion) molding in sheet formation is 220°C or lower. This makes it possible to suppress or prevent aggregation or thermal degradation of the cellulose components in the cellulose-based polysaccharide (B) having a lignin content of 10% by mass or lower, thereby controlling the balance between hydrophobic and hydrophilic materials. In this specification, the water contact angle is measured using the method described in the Examples section below.

[0015] Hereinafter, an embodiment of the styrene-based resin composition sheet according to the present embodiment formed using a styrene-based resin composition as a main component will be described, followed by a description of the properties of the sheet and a food container molded from the sheet. As mentioned above, the styrene-based resin composition sheet can be molded without using a styrene-based resin composition. When the styrene-based resin composition sheet is not made from a styrene-based resin composition as a raw material, the components of the sheet, namely, the styrene-based resin (A) and the cellulose-based polysaccharide (B) having a lignin content of 10% by mass or less, as well as the dispersant (C), compatibilizer (D), and optional additional components, are described by reference to the contents explained in the section on the styrene-based resin composition below.

[0016] (Styrene-based resin composition) The styrene-based resin composition forming the styrene-based resin composition sheet of this embodiment preferably contains 70 to 97 mass% of a styrene-based resin (A) and 3 to 30 mass% of a cellulose-based polysaccharide (B) having a lignin content of 10 mass% or less. By containing predetermined amounts of the styrene-based resin (A) and the cellulose-based polysaccharide (B) as the styrene-based resin composition that is the main component of the styrene-based resin composition sheet of this embodiment, effects such as reduced environmental impact, excellent oil resistance and heat insulation, and little odor and coloration are achieved. The inclusion of the cellulose-based polysaccharide (B) can improve the oil resistance and heat insulation, which have been issues with the styrene-based resin (A). From the viewpoint of moldability, an embodiment using a composition containing a styrene-based resin (A) as the main component is desirable. Furthermore, the styrene-based resin composition of the present embodiment may further contain a dispersant (C), a compatibilizer (D), and optional additional components, if necessary.

[0017] <Styrene-based resin (a) (hereinafter also referred to as component (A))> In this embodiment, the content of the styrene-based resin (A) is 70 to 97% by mass relative to the total amount (100% by mass) of the styrene-based resin composition sheet or the styrene-based resin composition. By setting the content to 70% by mass or more, moldability can be improved. On the other hand, by setting the content to 97% by mass or less, the total content of the cellulose-based polysaccharide (B) can be ensured, and heat resistance, oil resistance, etc. can be improved. In this embodiment, the content of the styrene-based resin (A) is 70 to 97 mass %, and preferably 80 to 95 mass %, relative to the total amount (100 mass %) of the styrene-based resin composition sheet or the styrene-based resin composition.

[0018] The MFR (200°C, 5 kg) of the styrene-based resin (A) in the present invention is preferably 2 (g / 10 min) or more. It is preferably 5 (g / 10 min) or more, more preferably 8 (g / 10 min) to 30 (g / 10 min), and even more preferably 10 (g / 10 min) to 25 (g / 10 min). This is because melt mixing at 240°C or less is necessary to prevent discoloration and fading of the cellulose-based polysaccharide (B). The MFR in this specification is calculated as a value measured in accordance with ISO 1133. Furthermore, in order to improve adhesion to the cellulose polysaccharide (B) and increase vacuum formability, the styrene resin (A) preferably contains unsaturated carboxylic acid monomer units. The content of the unsaturated carboxylic acid monomer units is preferably 2.0 to 16.0% by mass, more preferably 4 to 14% by mass, and even more preferably 8 to 13% by mass, based on the total mass of the styrene resin (A). The styrene-based resin (A) may be used alone or in a blend of two or more.

[0019] The styrene-based resin (A) that can be used in this embodiment is preferably a polymer having styrene-based monomer units, and more preferably a copolymer having styrene-based monomer units. Furthermore, the styrene-based resin (A) is more preferably a styrene-based copolymer resin obtained by polymerizing a styrene-based monomer with one or more monomers selected from other vinyl monomers copolymerizable with the styrene-based monomer and rubbery polymers. The styrene-based resin (A) in the present invention is not particularly limited, but examples thereof include polystyrene, a rubber-modified styrene-based resin in which particles of a rubbery polymer (a1) (hereinafter referred to as rubbery polymer particles (a1)) are dispersed in a matrix, a styrene-based copolymer resin having styrene-based monomer units, and mixtures thereof.

[0020] <<Polystyrene>> In this embodiment, polystyrene refers to a homopolymer obtained by polymerizing a styrene-based monomer, and a commonly available one can be appropriately selected and used. Examples of styrene-based monomers constituting polystyrene include, in addition to styrene, α-methylstyrene, α-methyl-p-methylstyrene, ο-methylstyrene, m-methylstyrene, p-methylstyrene, vinyltoluene, ethylstyrene, isobutylstyrene, and t-butylstyrene, as well as styrene derivatives such as bromostyrene and indene. From an industrial perspective, styrene is particularly preferred. These styrene-based monomers can be used alone or in combination. While polystyrene may contain further monomer units other than the above-mentioned styrene-based monomer units within the scope of the present invention, polystyrene typically consists of styrene-based monomer units.

[0021] <<Rubber-modified styrene resin>> In this embodiment, the rubber-modified styrene-based resin is a resin in which particles of a rubber-like polymer (a1) (also referred to as rubber-like polymer particles (a1)) are dispersed in a styrene resin as a polymer matrix phase, and can be produced by polymerizing a styrene-based monomer in the presence of the rubber-like polymer (a1).

[0022] -Polymer matrix phase- The styrene-based monomer that constitutes the polymer matrix phase of the rubber-modified styrene-based resin of this embodiment is the same as the styrene-based monomer that constitutes the polystyrene, and therefore will not be described here. The polymer matrix phase of the rubber-modified styrene-based resin of this embodiment is preferably composed of a styrene-based polymer containing a styrene-based monomer unit. The monomer unit constituting the styrene-based polymer of this embodiment is preferably a styrene-based monomer unit and / or a vinyl-based monomer unit (i) copolymerizable with the styrene-based monomer. Therefore, the styrene-based polymer is preferably one or more selected from the group consisting of the above-mentioned polystyrene and the styrene-based copolymer resins described below. As described below, examples of the styrene-based copolymer resin include styrene-(meth)acrylic acid ester copolymers. The term "composed of" means that 50% by mass or more, preferably 70% by mass or more, and more preferably 90% by mass or more of the total amount of the polymer matrix phase is occupied by the styrene polymer. Of the monomer units constituting the styrene-based polymer of this embodiment, the content of the styrene-based monomer units is preferably 50 to 100 mass% relative to the entire styrene-based polymer, more preferably 60 to 100 mass%, even more preferably 70 to 100 mass%, even more preferably 80 to 100 mass%, and still more preferably 90 to 100 mass%. The contents of the styrene-based monomer units in the styrene-based polymer and the vinyl-based monomer units (i) copolymerizable with styrene-based monomers other than the styrene-based monomer units 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.

[0023] In this embodiment, the vinyl monomer (i) is preferably one or more selected from the group consisting of unsaturated carboxylic acid monomers and unsaturated carboxylic acid ester monomer units, and is not particularly limited, but examples thereof include (meth)acrylic acid, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, cyclohexyl (meth)acrylate, etc. These monomers may be used alone or in combination of two or more. The term "(meth)acrylic acid" includes both acrylic acid and methacrylic acid.

[0024] -Rubber polymer particles (a1)- The rubber-like polymer particles (a1) contained in the rubber-modified styrene-based resin of this embodiment may, for example, encapsulate a styrene-based polymer obtained from the above-mentioned styrene-based monomer inside and / or may have a styrene-based polymer grafted onto the outside.

[0025] Examples of materials that can be used for the rubbery polymer (a1) or rubbery polymer particles (a1) of this embodiment include polybutadiene, polybutadiene containing polystyrene, polyisoprene, natural rubber, polychloroprene, styrene-butadiene copolymer, and acrylonitrile-butadiene copolymer, with polybutadiene or styrene-butadiene copolymer being preferred. As polybutadiene, both high-cis polybutadiene with a high cis content and low-cis polybutadiene with a low cis content can be used. Furthermore, the structure of the styrene-butadiene copolymer can be either a random structure or a block structure. One or more of these rubbery polymers (a1) can be used. Saturated rubbers obtained by hydrogenating butadiene rubbers can also be used. Examples of such rubber-modified styrene resins include HIPS (high impact polystyrene), ABS resin (acrylonitrile-butadiene-styrene copolymer), AAS resin (acrylonitrile-acrylic rubber-styrene copolymer), and AES resin (acrylonitrile-ethylene propylene rubber-styrene copolymer).

[0026] In this embodiment, when the rubber-modified styrene resin is a HIPS resin, the particularly preferred rubber polymer (a1) is a high-cis polybutadiene having 90 mol % or more of cis-1,4 bonds. In the high-cis polybutadiene, vinyl-1,2 bonds are preferably 6 mol % or less, and particularly preferably 3 mol % or less. The content of isomers having a cis-1,4, trans-1,4, or vinyl-1,2 structure as structural unit isomers of the high-cis polybutadiene can be calculated by measuring using an infrared spectrophotometer and processing the data by the Morello method. The high-cis polybutadiene can be easily obtained by a known production method, for example, by polymerizing 1,3-butadiene using a catalyst containing an organoaluminum compound and a cobalt or nickel compound.

[0027] In this embodiment, the content of the rubber-like polymer (a1) contained in the rubber-modified styrene-based resin (excluding the encapsulated styrene-based polymer) is preferably 2 to 10 mass% and more preferably 3 to 8 mass% relative to 100 mass% of the rubber-modified styrene-based resin. If the content of the rubber-like polymer (a1) is less than 2 mass%, the impact resistance of the styrene-based resin may be reduced. If the content of the rubber-like polymer (a1) is more than 10 mass%, the appearance of the molded article may be reduced. In the present disclosure, the content of the rubber-like polymer (a1) contained in the rubber-modified styrene-based resin is a value calculated using pyrolysis gas chromatography. Similarly, the content of all rubbery polymers present in the styrene-based resin composition sheet is the sum of the amount of so-called rubber components (conjugated diene-based polymers) contained in the rubber-modified styrene-based resin (rubbery polymer (a1)) and the amount of rubber components (rubbery polymer (a2)) derived from the elastomer (compatibilizer (D)) added as needed, and does not include the amount of styrene-based polymers (so-called polymer matrix phase) encapsulated within the rubbery polymer particles (a1).

[0028] In this embodiment, the average particle size of the rubber-like polymer particles (a1) contained in the rubber-modified styrene-based resin is preferably 0.5 to 2.5 μm, more preferably 0.8 to 2.0 μm, from the viewpoint of impact strength. In the present disclosure, the average particle size of the rubber-like polymer particles (a1) contained in the rubber-modified styrene-based resin can be measured by the following method. An ultrathin section with a thickness of 75 nm is prepared from a rubber-modified styrene-based resin stained with osmium tetroxide, and a photograph is taken at a magnification of 10,000 times using an electron microscope. In the photograph, the black-stained particles are rubber-like polymer particles (a1). From the photograph, the following mathematical formula (N1): Average particle diameter=ΣniDri 3 / ΣniDri 2 (N1) (In the above formula (N1), ni is the number of rubber-like polymer particles (a1) having a particle diameter Dri, and the particle diameter Dri is the particle diameter calculated as a circle-equivalent diameter from the area of ​​the particle in the photograph.) The area-average particle diameter is calculated by the above equation, and is defined as the average particle diameter of the rubber-like polymer particles (a1). This measurement is carried out by scanning a photograph at a resolution of 200 dpi and using particle analysis software of an image analyzer IP-1000 (manufactured by Asahi Kasei Corporation).

[0029] In this embodiment, the reduced viscosity of the rubber-modified styrene-based resin (which is an index of the molecular weight of the rubber-modified styrene-based resin) is preferably in the range of 0.50 to 0.85 dL / g, more preferably in the range of 0.55 to 0.80 dL / g. If it is less than 0.50 dL / g, there is a risk that the impact strength will decrease, and if it exceeds 0.85 dL / g, there is a risk that the moldability will decrease due to a decrease in fluidity. In the present disclosure, the reduced viscosity of the rubber-modified styrene-based resin is a value measured in a toluene solution at 30° C. and a concentration of 0.5 g / dL.

[0030] In this embodiment, the rubber-modified styrene-based resin can be produced by, but is not limited to, bulk polymerization (or solution polymerization) in which a styrene-based monomer (and a solvent) is polymerized in the presence of the rubber-like polymer (a1), or bulk-suspension polymerization in which the reaction transitions to suspension polymerization during the course of the reaction, or emulsion graft polymerization in which a styrene-based monomer is polymerized in the presence of a rubber-like polymer (a1) latex. In bulk polymerization, the rubber-modified styrene-based resin can be produced by continuously supplying a mixed solution containing the rubber-like polymer (a1) and the styrene-based monomer, and optionally an organic solvent, an organic peroxide, and / or a chain transfer agent, to a polymerization apparatus configured as a complete mixing reactor or a tank reactor and a plurality of tank reactors connected in series.

[0031] <<Styrene copolymer resin>> In this embodiment, the styrene-based copolymer resin refers to a resin containing styrene-based monomer units, unsaturated carboxylic acid-based monomer units, and optionally unsaturated carboxylic acid ester-based monomer units. In the styrene-based copolymer resin of the present invention, the content of styrene-based monomer units is preferably 69 to 98% by mass, more preferably 74 to 96% by mass, and even more preferably 77 to 92% by mass, when the total content of the styrene-based monomer units, unsaturated carboxylic acid-based monomer units, and unsaturated carboxylic acid ester-based monomer units is taken as 100% by mass. By setting the content to 69% by mass or more, the refractive index of the styrene-based resin (a) can be improved. On the other hand, by setting the content to 98% by mass or less, it becomes difficult to obtain the desired amounts of the unsaturated carboxylic acid-based monomer units and the optional unsaturated carboxylic acid ester-based monomer units described below, making it difficult to achieve the effects described below of these monomer units.

[0032] In the styrene-based copolymer resin of this embodiment, the unsaturated carboxylic acid-based monomer units serve to improve heat resistance. When the total content of the styrene-based monomer units, unsaturated carboxylic acid-based monomer units, and unsaturated carboxylic acid ester-based monomer units in the styrene-based copolymer resin is taken as 100% by mass, the content of the unsaturated carboxylic acid-based monomer units is preferably 2 to 16% by mass, more preferably 4 to 14% by mass, and even more preferably 8 to 13% by mass. By setting this content to 2% by mass or more, the dispersibility of cellulose can be improved, and the optical transparency, appearance, and heat resistance can be further improved. On the other hand, by setting this content to 16% by mass or less, the fluidity and mechanical properties of the resin can be improved.

[0033] Generally, styrene-methacrylic acid-based resins including styrene-methacrylic acid-methyl methacrylate copolymer resins, which are an example of styrene-based copolymer resins, are produced by radical polymerization in most cases on an industrial scale. In the present embodiment, however, in order to suppress the gelation reaction in the devolatilization step, polymerization can be carried out by adding various alcohols to the polymerization system. The unsaturated carboxylic acid ester monomer can be used to suppress the dehydration reaction of the unsaturated carboxylic acid monomer through intermolecular interaction with the unsaturated carboxylic acid monomer and to improve the mechanical strength of the resin. Furthermore, the unsaturated carboxylic acid ester monomer also contributes to improving resin properties such as weather resistance and surface hardness.

[0034] In the styrene-based copolymer resin of this embodiment, when the total content of the styrene-based monomer units, unsaturated carboxylic acid-based monomer units, and unsaturated carboxylic acid ester-based monomer units is taken as 100% by mass, the content of the unsaturated carboxylic acid ester-based monomer units is preferably 0 to 15% by mass, more preferably 1 to 12% by mass, and even more preferably 2 to 10% by mass. By setting the content to 15% by mass or less, the light transmittance and fluidity of the resin can be improved. Furthermore, by setting the content of the unsaturated carboxylic acid ester-based monomer units to 0% by mass, heat resistance can be improved and costs can be reduced, but from the above-mentioned perspective, the content of the unsaturated carboxylic acid ester-based monomer units can also be set to more than 0% by mass. In addition, when an unsaturated carboxylic acid monomer and an unsaturated carboxylic acid ester monomer unit are bonded adjacent to each other, a dealcoholization reaction may occur under certain conditions when a high-temperature, high-vacuum devolatilizer is used, resulting in the formation of a six-membered cyclic acid anhydride. The copolymer resin of this embodiment may contain this six-membered cyclic acid anhydride, but since this reduces fluidity, it is preferable that the amount of the six-membered cyclic acid anhydride produced is as small as possible.

[0035] In the present embodiment, the contents of the styrene monomer unit (for example, styrene monomer unit), the unsaturated carboxylic acid monomer unit (for example, methacrylic acid monomer unit), and the unsaturated carboxylic acid ester monomer unit (for example, methyl methacrylate monomer unit) in the styrene copolymer resin 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] In the present embodiment, the styrene-based copolymer resin may further contain monomer units other than the styrene-based monomer units, the unsaturated carboxylic acid-based monomer units, and the unsaturated carboxylic acid ester-based monomer units as an optional component, as long as the effects of the present invention are not impaired. However, the copolymer resin in the present invention is typically preferably composed of the styrene-based monomer units, the unsaturated carboxylic acid-based monomer units, and the unsaturated carboxylic acid ester-based monomer units.

[0037] The styrene-based monomer constituting the styrene-based copolymer resin of this embodiment is not particularly limited, but examples thereof include styrene, α-methylstyrene, α-methyl-p-methylstyrene, ο-methylstyrene, m-methylstyrene, p-methylstyrene, vinyltoluene, ethylstyrene, isobutylstyrene, t-butylstyrene, bromostyrene, and styrene derivatives such as indene. From an industrial viewpoint, styrene is preferred as the styrene-based monomer. These styrene-based monomers can be used alone or in combination of two or more.

[0038] The unsaturated carboxylic acid monomer constituting the styrene copolymer resin of this embodiment is not particularly limited, but examples thereof include methacrylic acid, acrylic acid, maleic anhydride, maleic acid, fumaric acid, itaconic acid, etc. As the unsaturated carboxylic acid monomer, methacrylic acid is preferred because it has a significant effect of improving heat resistance, is liquid at room temperature, and has excellent handleability. These unsaturated carboxylic acid monomers can be used alone or in combination of two or more.

[0039] The unsaturated carboxylic acid ester monomer constituting the styrene copolymer resin of this embodiment is not particularly limited, but examples thereof include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, and cyclohexyl (meth)acrylate. As the (meth)acrylic acid ester monomer, methyl (meth)acrylate is preferred because it has little effect on the deterioration of heat resistance. These unsaturated carboxylic acid ester monomers can be used alone or in combination of two or more.

[0040] As the styrene copolymer resin of the present embodiment, a styrene-methyl (meth)acrylate copolymer, a styrene-ethyl (meth)acrylate copolymer, a styrene-propane (meth)acrylate copolymer, a styrene-butyl (meth)acrylate copolymer, a styrene-methyl (meth)acrylate-butyl methacrylate copolymer, or a styrene-methyl (meth)acrylate-methacrylic acid copolymer is preferred.

[0041] In this embodiment, the weight-average molecular weight (Mw) of the styrene copolymer resin is preferably 100,000 to 350,000, more preferably 120,000 to 300,000, and even more preferably 140,000 to 240,000. When the weight-average molecular weight (Mw) is 100,000 to 350,000, a resin with an excellent balance between mechanical strength and fluidity is obtained, and the amount of gel contamination is also reduced. The weight-average molecular weight (Mw) is a value obtained by gel permeation chromatography in terms of standard polystyrene.

[0042] The styrene-based resin (A) of this embodiment may be a blend of one or more of the rubber-modified styrene-based resins and one or more of the styrene-based copolymer resins. In this case, the mixing ratio of the rubber-modified styrene-based resin to the styrene-based copolymer resin can be appropriately changed depending on the intended use. For example, in a system in which the amount of the rubber-modified styrene-based resin is less than the amount of the styrene-based copolymer resin, the styrene-based copolymer resin is preferably contained in an amount of 0.1 to 30% by mass relative to the total amount (100% by mass) of the styrene-based resin (A). On the other hand, in a system in which the amount of the rubber-modified styrene-based resin is more than the amount of the styrene-based copolymer resin, the styrene-based copolymer resin is preferably contained in an amount of 70 to 99.9% by mass relative to the total amount (100% by mass) of the styrene-based resin (A).

[0043] In the present embodiment, the polymerization method for the styrene copolymer resin is not particularly limited, but for example, a bulk polymerization method or a solution polymerization method can be suitably adopted as a radical polymerization method. The polymerization method mainly includes a polymerization step of polymerizing polymerization raw materials (monomer components) and a devolatilization step of removing volatile components such as unreacted monomers and polymerization solvent from the polymerization product.

[0044] An example of a method for polymerizing a styrene copolymer resin that can be used in this embodiment will be described below. When the polymerization raw materials are polymerized to obtain the styrene copolymer resin, a polymerization initiator and a chain transfer agent are typically contained in the polymerization raw material composition. Examples of polymerization initiators used in the polymerization of styrene copolymer resins 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-butyl peroxyacetate; ketone peroxides such as acetylacetone peroxide; and hydroperoxides such as t-butyl hydroperoxide. Among these, 1,1-bis(t-butylperoxy)cyclohexane is preferred from the viewpoints of decomposition rate and polymerization rate. Examples of the chain transfer agent used in the polymerization of the styrene copolymer resin include α-methylstyrene linear dimer, n-dodecyl mercaptan, t-dodecyl mercaptan, and n-octyl mercaptan.

[0045] Solution polymerization using a polymerization solvent can be used as a polymerization method for styrene copolymer resins, if necessary. Examples of polymerization solvents include aromatic hydrocarbons, such as ethylbenzene, and dialkyl ketones, such as methyl ethyl ketone. These solvents can be used alone or in combination. Other polymerization solvents, such as aliphatic hydrocarbons, can be added to the aromatic hydrocarbons as long as they do not reduce the solubility of the polymerization product. These polymerization solvents are preferably used in an amount not exceeding 25 parts by weight per 100 parts by weight of the total monomers. If the amount of polymerization solvent exceeds 25 parts by weight per 100 parts by weight of the total monomers, the polymerization rate tends to decrease significantly and the mechanical strength of the resulting resin tends to decrease significantly. Adding the polymerization solvent at a ratio of 5 to 20 parts by weight per 100 parts by weight of the total monomers before polymerization facilitates uniform quality and is also preferable in terms of controlling the polymerization temperature.

[0046] In this embodiment, the apparatus used in the polymerization step to obtain a styrene-based copolymer resin is not particularly limited and may be appropriately selected according to the polymerization method of the styrene-based resin. For example, when bulk polymerization is employed, a polymerization apparatus having one or more complete mixing reactors connected together can be used. The devolatilization step is also not particularly limited. For example, when bulk polymerization is employed, polymerization is continued until the final unreacted monomer content is preferably 50% by mass or less, more preferably 40% by mass or less, and devolatilization treatment is performed by a known method to remove volatile components such as the unreacted monomer. More specifically, for example, a conventional devolatilization apparatus such as a flash drum, a twin-screw devolatilizer, a thin-film evaporator, or an extruder can be used, but a devolatilization apparatus with a small retention area is preferred. The devolatilization temperature is typically about 190 to 280°C, and more preferably 190 to 260°C from the viewpoint of suppressing the formation of a six-membered cyclic acid anhydride due to the adjacency of methacrylic acid and methyl methacrylate. The pressure for the devolatilization treatment is usually about 0.13 to 4.0 kPa, preferably 0.13 to 3.0 kPa, and more preferably 0.13 to 2.0 kPa. Desirable devolatilization methods include, for example, a method of removing volatile components under reduced pressure while heating, and a method of removing volatile components through an extruder or the like designed for the purpose of devolatilization.

[0047] <Cellulosic Polysaccharide (B) (hereinafter also referred to as component (B))> The styrene-based resin composition or the styrene-based resin composition sheet of the present embodiment contains a cellulose-based polysaccharide (B). In this embodiment, the content of the cellulose polysaccharide (B) is 3 to 30% by mass relative to the total amount (100% by mass) of the styrene-based resin composition or the styrene-based resin composition sheet. By setting the content of the cellulose polysaccharide (B) to 3% by mass or more, it is possible to improve thermal shape retention and oil resistance. On the other hand, if the content is too high, the flowability decreases, resulting in a significant decrease in moldability. The cellulose content in the styrene-based resin composition sheet or the styrene-based resin composition that is a precursor to the sheet can be confirmed by dissolving the styrene-based resin composition sheet or the styrene-based resin composition in a solvent that dissolves the styrene-based resin (A), removing the undissolved matter, and drying the resultant at 120°C for 4 hours, and then measuring the mass of the solution.

[0048] In this embodiment, at least one of the average lengths of the minor axis d1 and major axis d2 of the cellulose polysaccharide (B) is 0.03 to 80 μm, preferably 0.05 to 60 μm, preferably 0.1 to 50 μm, and more preferably 0.2 to 30 μm. If the average lengths of the minor axis and major axis are outside the above ranges, the thermal mold retention may not be sufficiently exhibited, or moldability may be reduced. On the other hand, if the average lengths of the minor axis and major axis are within the above ranges, aggregation of cellulose particles can be reduced, and dispersibility in the styrene-based resin (A) is improved, resulting in improved oil resistance and moldability. In the present invention, the average minor axis length d1 of the cellulose polysaccharide (B) is determined by measuring the minor axis lengths (minimum lengths) of 100 cellulose polysaccharides (B) under a transmission electron microscope (magnification: 5000x) and calculating the arithmetic mean. Meanwhile, the average major axis length of cellulose is determined by measuring the major axis lengths (maximum lengths) of 100 cellulose polysaccharides (B) under a transmission electron microscope (magnification: 5000x) and calculating the arithmetic mean. The minor axis length (minimum length) of the cellulose polysaccharide (B) refers to the length of the thinnest (or shortest) point on the image, and the major axis length (maximum length) of the cellulose polysaccharide (B) refers to the length of the longest point on the image. Thermal shape retention is affected by the shape of the cellulose; in the case of fibers, it is affected by the minor axis, while in the case of scale-like or granular cellulose, it is affected by the average diameter of the major axis. The shape of the cellulose polysaccharide (B) in the present invention is not particularly limited, and examples thereof include spherical, irregular, powdery, scaly, fibrous, and rod-like shapes. The aspect ratio (d1 / d2) of the cellulose polysaccharide (B) in the present invention is preferably 1-500, more preferably 1.2-300, further preferably 1.5-200, and particularly preferably 2-100.

[0049] The cellulose polysaccharide (B) in the present invention refers to a polysaccharide having a β-1,4-glucan structure, and includes cellulose and hemicellulose. The material of the cellulose polysaccharide (B) is not particularly limited, as long as the fibers constituting the cellulose polysaccharide (B) are formed from polysaccharides having a β-1,4-glucan structure. Examples of the cellulose polysaccharide (B) include cellulose fibers derived from higher plants [e.g., natural cellulose fibers (pulp fibers) such as wood fibers (wood pulp from conifers, broad-leaved trees, etc.), bamboo fibers, sugarcane fibers, seed hair fibers (cotton linters, bombax cotton, kapok, etc.), ginseng bark fibers (e.g., hemp, paper mulberry, Mitsumata, etc.), and leaf fibers (e.g., Manila hemp, New Zealand hemp, etc.)], animal-derived cellulose fibers (such as sea squirt cellulose), bacterial-derived cellulose fibers, and chemically synthesized cellulose fibers [cellulose acetate (acetic acid)]. Examples of the fiber that constitutes the cellulose polysaccharide (B) include organic acid esters such as cellulose acetate, cellulose propionate, cellulose butyrate, cellulose acetate propionate, and cellulose acetate butyrate; inorganic acid esters such as cellulose nitrate, cellulose sulfate, and cellulose phosphate; mixed acid esters such as cellulose acetate nitrate; hydroxyalkyl celluloses (e.g., hydroxyethyl cellulose (HEC), hydroxypropyl cellulose, etc.); carboxyalkyl celluloses (carboxymethyl cellulose (CMC), carboxyethyl cellulose, etc.); alkyl celluloses (methyl cellulose, ethyl cellulose, etc.); and cellulose derivative fibers such as regenerated cellulose (rayon, cellophane, etc.). These fibers that constitute the cellulose polysaccharide (B) may be used alone or in combination of two or more.

[0050] Among the fibers constituting the above-mentioned cellulose polysaccharide (B), preferred are plant-derived cellulose fibers, for example, cellulose fibers derived from pulp such as wood fibers (wood pulp of coniferous trees, broad-leaved trees, bamboo, etc.) and seed fiber fibers (cotton linter pulp, etc.), because they have high production efficiency in terms of dispersibility, rigidity, and impact resistance when producing the cellulose polysaccharide (B) and have appropriate fiber diameters and lengths. In this embodiment, the lignin content is preferably 10% by mass or less, more preferably 5% by mass or less, relative to the cellulose polysaccharide (B). If the lignin content is more than 10% by mass, odor and coloring will increase during thermal processing, and lignin degradation products will appear as black spots on the charcoal, reducing product value, and causing holes during microwave heating. Furthermore, in this embodiment, the hemicellulose content is preferably 1% by mass or more relative to the cellulose-based polysaccharide (B). The inclusion of hemicellulose improves dispersibility in the styrene-based resin (A), thereby improving rigidity and molded appearance. In the present invention, it is preferable to leave these components in a suitable content range during the cellulose production process rather than completely removing them. Hemicellulose is a polysaccharide composed of sugars such as mannan and xylan, and forms hydrogen bonds with cellulose to connect microfibrils. Furthermore, since the solubility parameter (SP value) of hemicellulose is more hydrophobic than that of cellulose, hemicellulose is thought to have the effect of reducing the difference in SP value between the styrene-based resin (A) and the cellulose-based polysaccharide (B). The amount of hemicellulose can be adjusted by subjecting natural wood raw materials with a high hemicellulose content to a purification treatment to reduce it to a desired amount. When a raw material with a low hemicellulose content is used, the desired amount can be adjusted by adding hemicellulose obtained by extraction from another raw material. In this case, it is acceptable if the structure of the terminals of hemicellulose or the like is partially different from that of the natural product due to purification or extraction treatment.

[0051] In this embodiment, in order to reduce the difference in SP value between the styrene-based resin (A) and the cellulose-based polysaccharide (B), it is more preferable that hemicellulose is contained in an amount of 1% by mass or more and 25% by mass or less, even more preferable that it is contained in an amount of 2% by mass or more and 20% by mass or less, even more preferable that it is contained in an amount of 3% by mass or more and 20% by mass or less, even more preferable that it is contained in an amount of 5% by mass or more and 19.5% by mass or less, and especially preferable that it is contained in an amount of 7% by mass or more and 19.3% by mass or less, relative to the cellulose-based polysaccharide (B) (100% by mass).

[0052] <Dispersant (C) (hereinafter also referred to as component (C))> The styrene-based resin composition or the styrene-based resin composition sheet of this embodiment may contain a dispersant (C) as needed. By containing the dispersant (C) in the styrene-based resin composition or the composition sheet, the cellulose polysaccharide (B) can be uniformly dispersed in the styrene-based resin (A). As a result, the thermal shape retention and oil resistance of the styrene-based resin composition sheet as a whole can be improved without reducing the mechanical strength. In this embodiment, the content of the dispersant (C) is 0 to 10 mass%, preferably 0.5 to 5 mass%, and more preferably 1 to 3 mass%, relative to the total amount (100 mass%) of the styrene-based resin composition or the styrene-based resin composition sheet. The dispersant (C) in this embodiment may be a fatty acid ester compound, a polyethylene glycol compound, a terpene compound, a rosin compound, a fatty acid amide, a fatty acid compound, or a fatty acid metal salt compound, etc. In particular, the dispersant (C) is preferably one or more compounds selected from the group consisting of a fatty acid ester compound, a polyethylene glycol compound, a terpene compound, and a rosin compound.

[0053] Examples of the aliphatic ester compounds include methyl laurate, methyl myristate, methyl palmitate, methyl stearate, methyl oleate, methyl erucate, methyl behenate, butyl laurate, butyl stearate, isopropyl myristate, isopropyl palmitate, octyl palmitate, coconut fatty acid octyl ester, octyl stearate, tallow fatty acid octyl ester, lauryl laurate, stearyl stearate, behenyl behenate, cetyl myristate, esters of linear, unbranched saturated monocarboxylic acids having 28 to 30 carbon atoms (hereinafter abbreviated as montanic acid) and ethylene glycol, esters of montanic acid and glycerin, ... Examples include esters of montanic acid and butylene glycol, esters of montanic acid and trimethylolethane, esters of montanic acid and trimethylolpropane, esters of montanic acid and pentaerythritol, glycerin monostearate, sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan monooleate, sorbitan sesquioleate, sorbitan trioleate, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan trioleate, etc. These may be used alone or in combination of two or more.

[0054] The polyethylene glycol compound is not particularly limited, and examples thereof include polyethylene glycols, polypropylene glycols, polyethylene glycol alkyl ethers, polypropylene glycol alkyl ethers, polyethylene glycol aryl ethers, polypropylene glycol aryl ethers, polyethylene glycol alkyl aryl ethers, polypropylene glycol alkyl aryl ethers, polyethylene glycol glycerin esters, polypropylene glycol glycerin esters, polyethylene sorbitol esters, polypropylene glycol sorbitol esters, polyethylene glycolated ethylenediamines, polypropylene glycolated ethylenediamines, polyethylene glycolated diethylenetriamines, and polypropylene glycolated diethylenetriamines.

[0055] The terpene resin typically refers to a resin obtained by copolymerizing a terpene monomer alone, or a terpene monomer with an aromatic monomer, or a terpene monomer with a phenol in an organic solvent in the presence of a Friedel-Crafts catalyst, but is not limited thereto. Examples of the terpene monomer include, but are not limited to, C5 hemiterpenes such as isoprene, C10 monoterpenes such as α-pinene, β-pinene, dipentene, d-limonene, myrcene, alloocimene, ocimene, α-phellandrene, α-terpinene, γ-terpinene, terpinolene, 1,8-cineole, 1,4-cineole, α-terpineol, β-terpineol, γ-terpineol, sabinene, paramentadienes, and carenes, C15 sesquiterpenes such as caryophyllene and longifolene, and C20 diterpenes. Among these compounds, α-pinene, β-pinene, dipentene, and d-limonene are particularly preferred. Examples of the aromatic monomer include, but are not limited to, styrene, α-methylstyrene, vinyltoluene, and isopropenyltoluene. Examples of the phenols include, but are not limited to, phenol, cresol, xylenol, and bisphenol A. Alternatively, the terpene resin may be a hydrogenated terpene resin obtained by subjecting the obtained terpene resin to a hydrogenation treatment. For example, preferred terpene resins include α-pinene resin, β-pinene resin, aromatic modified terpene resin, terpene phenol resin, and hydrogenated terpene resin. The terpene resin may be used alone or in combination of two or more.

[0056] Examples of the rosin-based resin include rosins such as gum rosin, wood rosin, and tall oil rosin, as well as stabilized rosins obtained by disproportionating or hydrogenating the rosins, polymerized rosins (typically dimers) that are polymers of the rosins, and modified rosins modified with unsaturated acids such as maleic acid, fumaric acid, and (meth)acrylic acid. Examples of rosin derivative resins include esters of the rosin-based resins, phenol-modified products, and esters thereof. The rosin-based resins may be used alone or in combination of two or more. The rosin-based resins or rosin derivative resins used in the present invention are not limited to these resins. Examples of the aliphatic amide include stearic acid amide, oleic acid amide, erucic acid amide, behenic acid amide, ethylene bisstearic acid amide, ethylene bisoleic acid amide, ethylene biserucic acid amide, ethylene bislauric acid amide, etc. These may be used alone or in combination of two or more.

[0057] Specific examples of saturated fatty acids among the above fatty acid compounds include lauric acid (dodecanoic acid), isodecanoic acid, tridecanoic acid, myristic acid (tetradecanoic acid), pentadecylic acid, palmitic acid (hexadecanoic acid), margaric acid (heptadecanoic acid), stearic acid (octadecanoic acid), isostearic acid, tuberculostearic acid (nonadecanoic acid), 2-hydroxystearic acid, arachidic acid (icosanoic acid), behenic acid (docosanoic acid), lignoceric acid (tetradocosanoic acid), cerotic acid (hexadocosanoic acid), montanic acid (octadocosanoic acid), and melissic acid, and particularly include lauric acid, palmitic acid, stearic acid, behenic acid, 12-hydroxystearic acid, and montanic acid. These may be used alone or in combination of two or more.

[0058] Specific examples of unsaturated fatty acids among the above fatty acid compounds include myristoleic acid (tetradecenoic acid), palmitoleic acid (hexadecenoic acid), oleic acid (cis-9-octadecenoic acid), elaidic acid (trans-9-octadecenoic acid), ricinoleic acid (octadecadienoic acid), vaccenic acid (cis-11-octadecenoic acid), linoleic acid (octadecadienoic acid), linolenic acid (9,11,13-octadecatrienoic acid), elestearic acid (9,11,13-octadecatrienoic acid), gadoleic acid (icosanoic acid), erucic acid (docosanoic acid), nervonic acid (tetradocosanoic acid), etc. These may be used alone or in combination of two or more. Examples of the fatty acid metal salts include lithium salts, calcium salts, magnesium salts, zinc salts, and aluminum salts of the fatty acids of the fatty acid compounds, which may be used alone or in combination of two or more.

[0059] <Compatibilizer (D) (hereinafter also referred to as component (D))> The styrene-based resin composition or styrene-based resin composition sheet of this embodiment may contain a compatibilizer (D) as needed. The compatibilizer (D) of the present invention can be any rubber-like polymer (a2) that can be used without any particular limitation. The compatibilizer (D) is preferably a rubber-like polymer (a2) modified with an unsaturated carboxylic acid, an anhydride thereof, or a derivative thereof. The content of the compatibilizer (D) of the present invention is preferably 0.5 to 10 mass%, more preferably 1 to 5 mass%, and even more preferably 2 to 4 mass%, relative to the total amount (100 mass%) of the styrene-based resin composition sheet or the styrene-based resin composition. In the styrene-based resin composition sheet or the styrene-based resin composition of the present invention, the content of the rubber component (the total amount of the rubbery polymer (a1) and the rubbery polymer (a2)) contained in the styrene-based resin composition sheet or the styrene-based resin composition is preferably 3 to 20 mass%, more preferably 5 to 15 mass%, and even more preferably 6 to 11 mass%, relative to the total amount (100 mass%) of the styrene-based resin composition sheet or the styrene-based resin composition.

[0060] Examples of the rubbery polymer (a2) of this embodiment include polybutadiene, polyisoprene, hydrogenated polyisoprene, polyisobutylene, polyacrylic acid ester, styrene-butadiene block copolymer, styrene-butadiene-styrene copolymer, styrene-isoprene block copolymer, styrene-isoprene-styrene block copolymer, styrene-ethylene-butylene-styrene copolymer, styrene-ethylene-propylene copolymer, hydrogenated styrene-butadiene block copolymer, hydrogenated styrene-butadiene-styrene block copolymer, hydrogenated styrene-isoprene block copolymer, and hydrogenated styrene-isoprene-styrene block copolymer. Examples of the elastomer include styrene-ethylene-butylene-styrene copolymer, styrene-ethylene-propylene copolymer, ethylene-propylene copolymer, ethylene-1-butene copolymer, ethylene-α-olefin copolymer, ethylene-propylene-ethylidene norbornene copolymer, ethylene-vinyl acetate copolymer, linear low-density polyethylene elastomer, acrylic elastomer, polyester-polyether coelastomer, polyamide elastomer, etc., and among these, styrene-ethylene-butylene-styrene copolymer, styrene-ethylene-propylene copolymer, ethylene-propylene copolymer, ethylene-1-butene copolymer, ethylene-α-olefin copolymer, and ethylene-propylene-ethylidene norbornene copolymer are preferred.

[0061] Examples of unsaturated carboxylic acids or anhydrides, or derivatives thereof, that modify the rubbery polymer (a2) of this embodiment include maleic acid, fumaric acid, itaconic acid, methylmaleic acid, 3,6-endomethylene-delta-4-tetrahydrophthalic acid, acrylic acid, methacrylic acid, crotonic acid, citraconic acid, maleic anhydride, itaconic anhydride, methylmaleic anhydride, 3,6-endomethylene-delta-4-tetrahydrophthalic anhydride, 2-methyl-3,6-endomethylene-delta-4-tetrahydrophthalic anhydride, 3-methyl-4-cyclohexene-1,2-dicarboxylic anhydride, glycidyl acrylate, glycidyl methacrylate, and derivatives of alkyl cyanoacrylates having 1 to 20 carbon atoms, with maleic acid and maleic anhydride being preferred. Examples of methods for modifying the rubbery polymer component with an unsaturated carboxylic acid or the like include graft polymerization of the unsaturated carboxylic acid or the like onto the rubbery polymer (a2).

[0062] Specific examples of the compatibilizer (D) of the present invention include maleic acid-modified styrene-ethylene-butylene-styrene copolymer, maleic acid-modified styrene-ethylene-propylene copolymer, maleic acid-modified ethylene-propylene copolymer, maleic acid-modified ethylene-1-butene copolymer, maleic acid-modified ethylene-α-olefin copolymer, maleic acid-modified ethylene-propylene-ethylidenenorbornene copolymer, maleic anhydride-modified styrene-ethylene-butylene-styrene copolymer, maleic anhydride-modified styrene-ethylene-propylene copolymer, maleic anhydride-modified ethylene-propylene copolymer, maleic anhydride-modified ethylene-1-butene copolymer, maleic anhydride-modified ethylene-α-olefin copolymer, maleic anhydride-modified ethylene-propylene-ethylidenenorbornene copolymer, and the like, and these can be used alone or in combination of two or more.

[0063] <Optional addition ingredients> In addition to the components (A) to (D), the styrene-based resin composition of this embodiment may contain optional components such as known additives and processing aids, as needed, within the range that does not impair the effects of the present invention. Examples of these additives and processing aids include lubricants, antioxidants, weathering agents, antistatic agents, and fillers.

[0064] The lubricant is as described above. Examples of the antioxidant include phenolic compounds, phosphorus compounds, and thioether compounds. Examples of the phenolic antioxidant 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)propionic acid amide], 4,4'-thiobis(6-tert-butyl-m-cresol), 2,2'-methylenebis(4-methyl-6-tert-butylphenol), 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 ester ] 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)butylic 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 of suitable bis(3-tert-butyl-4-hydroxyphenyl)propionyloxyethyl)isocyanurate include 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 alone or in combination of two or more.

[0065] Examples of the phosphorus-based antioxidant 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 diphosphite. tetra(tridecyl)isopropylidenediphenol 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)isopropylidenediphenol diphosphite, tetra(tridecyl)-4,4'-n- Butylidenebis(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)biphenylene diphosphonite, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 2,2'-methylenebis(4,6-tert-butylphenyl)-2-ethylhexylphospha phosphite, 2,2'-methylenebis(4,6-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]dioxaphosphepin-6-yl)oxy]ethyl)amine, phosphite of 2-ethyl-2-butylpropylene glycol and 2,4,6-tri-tert-butylphenol, etc. These may be used alone or in combination of two or more.

[0066] Examples of the thioether antioxidant include dialkyl thiodipropionates such as dilauryl thiodipropionate, dimyristyl thiodipropionate, and distearyl thiodipropionate, and pentaerythritol tetra(β-alkylmercaptopropionate) esters. These may be used alone or in combination of two or more.

[0067] As the weatherproofing agent, an ultraviolet absorber, a hindered amine light stabilizer, etc. can be used. Examples of the ultraviolet absorber include 2-hydroxybenzophenones such as 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, and 5,5'-methylenebis(2-hydroxy-4-methoxybenzophenone); 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-5'-methylphenyl)-5-chlorobenzotriazole, and the like. 2-(2'-hydroxyphenyl)benzotriazoles such as 2-(2'-hydroxy-3',5'-dicumylphenyl)benzotriazole, 2,2'-methylenebis(4-tert-octyl-6-(benzotriazolyl)phenol), and 2-(2'-hydroxy-3'-tert-butyl-5'-carboxyphenyl)benzotriazole; phenyl salicylate, resorcinol monobenzoate, 2,4-di-tert-butylphenyl-3,5-di-tert-butyl-4-hydroxybenzoate, 2,4-di-tert-amylphenyl-3,5-di-tert-butyl-4-hydroxybenzoate, hexadecyl-3,5-di-tert-butyl-4-hydroxybenzoate, substituted oxanilides such as 2-ethyl-2'-ethoxyoxanilide and 2-ethoxy-4'-dodecyloxanilide; cyanoacrylates such as ethyl-α-cyano-β,β-diphenylacrylate and methyl-2-cyano-3-methyl-3-(p-methoxyphenyl)acrylate; and triaryltriazines such as 2-(2-hydroxy-4-octoxyphenyl)-4,6-bis(2,4-di-tert-butylphenyl)-s-triazine, 2-(2-hydroxy-4-methoxyphenyl)-4,6-diphenyl-s-triazine, and 2-(2-hydroxy-4-propoxy-5-methylphenyl)-4,6-bis(2,4-di-tert-butylphenyl)-s-triazine.These may be used alone or in combination of two or more.

[0068] Examples of the hindered amine light stabilizer include 2,2,6,6-tetramethyl-4-piperidyl stearate, 1,2,2,6,6-pentamethyl-4-piperidyl stearate, 2,2,6,6-tetramethyl-4-piperidyl benzoate, bis(2,2,6,6-tetramethyl-4-piperidyl)sebacate, bis(1,2,2,6,6-tetramethyl-4-piperidyl)sebacate, bis(1-octoxy-2,2,6,6-tetramethyl-4-piperidyl)sebacate, tetrakis(2,2,6,6-tetramethyl-4-piperidyl)-1 ,2,3,4-butanetetracarboxylate, tetrakis(1,2,2,6,6-pentamethyl-4-piperidyl)-1,2,3,4-butanetetracarboxylate, bis(2,2,6,6-tetramethyl-4-piperidyl)·di(tridecyl)-1,2,3,4-butanetetracarboxylate, bis(1,2,2,6,6-pentamethyl-4-piperidyl)·di(tridecyl)-1,2,3,4-butanetetracarboxylate, bis(1,2,2,4,4-pentamethyl-4-piperidyl)-2-butyl-2-(3,5-di-tert-butyl-4-hydrogen hydroxybenzyl)malonate, 1-(2-hydroxyethyl)-2,2,6,6-tetramethyl-4-piperidinol / diethyl succinate polycondensate, 1,6-bis(2,2,6,6-tetramethyl-4-piperidylamino)hexane / 2,4-dichloro-6-morpholino-s-triazine polycondensate, 1,6-bis(2,2,6,6-tetramethyl-4-piperidylamino)hexane / 2,4-dichloro-6-tert-octylamino-s-triazine polycondensate, 1,5,8,12-tetrakis[2,4-bis(N-butyl-N-(2,2,6,6-tetramethyl -4-piperidyl)amino)-s-triazin-6-yl]-1,5,8,12-tetraazadodecane, 1,5,8,12-tetrakis[2,4-bis(N-butyl-N-(1,2,2,6,6-pentamethyl-4-piperidyl)amino)-s-triazin-6-yl]-1,5,8-12-tetraazadodecane, 1,6,11-tris[2,4-bis(N-butyl-N-(2,2,6,6-tetramethyl-4-piperidyl)amino)-s-triazin-6-yl]aminoundecane, 1,6,11-tris[2,4-bis(N-butyl-N-(1,2,2,Examples of the hindered amine compounds include 6,6-pentamethyl-4-piperidylamino-s-triazin-6-ylaminoundecane. These may be used alone or in combination of two or more.

[0069] As the antistatic agent, cationic, anionic, nonionic, amphoteric, fatty acid partial esters such as glycerin fatty acid monoesters, etc. can be used. Specifically, alkyltrimethylammonium salts, dialkyldimethylammonium salts, benzalkonium salts, N,N-bis(2-hydroxyethyl)-N-(3-dodecyloxy-2-hydroxypropyl)methylammonium methosulfate, (3-laurylamidopropyl)trimethylammonium methylsulfate, stearamidopropyldimethyl-2-hydroxyethylammonium nitrate, stearamidopropyldimethyl-2-hydroxyethylammonium phosphate, cationic polymers, alkyl sulfonates, alkylbenzene sulfonates, sodium alkyl diphenyl ether disulfonate, alkyl nitrate ester salts, phosphorus Acid alkyl ester salts, alkyl phosphate amine salts, stearic acid monoglyceride, pentaerythritol fatty acid esters, sorbitan monopalmitate, sorbitan monostearate, diglycerin fatty acid esters, alkyldiethanolamines, alkyldiethanolamine fatty acid monoesters, alkyldiethanolamides, polyoxyethylene dodecyl ethers, polyoxyethylene alkylphenyl ethers, polyethylene glycol monolaurate, polyoxyethylene alkylamines, polyoxyethylene alkylamides, polyether block copolymers, cetyl betaine, hydroxyethyl imidazoline sulfate, etc. These may be used alone or in combination of two or more.

[0070] As the filler, talc, calcium carbonate, barium sulfate, carbon fiber, mica, wollastonite, whisker, etc. can be used. Other optional additives may also be added, such as anti-blocking agents, colorants, anti-blooming agents, surface treatment agents, antibacterial agents, and anti-eye discharge agents (anti-eye discharge agents such as silicone oils described in JP 2009-120717 A, monoamide compounds of higher aliphatic carboxylic acids, and monoester compounds obtained by reacting higher aliphatic carboxylic acids with monohydric to trihydric alcohol compounds).

[0071] In this embodiment, the total content of the above-mentioned optional additive components may be 0.05 to 5% by mass in the styrene-based resin composition.

[0072] The styrene-based resin composition of this embodiment may consist essentially of only component (A), component (B), and any additional components, or essentially of only component (A), component (B), component (C), and any additional components, or essentially of only component (A), component (B), component (D), and any additional components, or essentially of only component (A), component (B), component (C), component (D), and any additional components. In addition, another embodiment of the styrene-based resin composition of this embodiment may consist essentially of component (A) and component (B), or essentially of component (A), component (B), and component (C), or essentially of component (A), component (B), and component (D), or essentially of component (A), component (B), component (C), and component (D). In this specification, the phrase "consisting essentially of only the component (A), the component (B), and any additional components" means that, relative to the total amount (100% by mass) of the styrene resin composition, 95 to 100% by mass (preferably 98 to 100% by mass) is the component (A) and the component (B), or the component (A), the component (B), and any additional components. The styrene-based resin composition of the present embodiment may contain impurities in addition to the components (A) to (D) and optional additional components, as long as the effects of the present invention are not impaired.

[0073] [Method of producing styrene-based resin composition] The styrene-based resin composition of this embodiment can be produced by melt-kneading the components by any method. For example, a high-speed mixer such as a Henschel mixer, a batch mixer such as a Banbury mixer, a single-screw or twin-screw continuous mixer, a roll mixer, or the like can be used alone or in combination. The heating temperature during kneading is usually selected from the range of 180 to 250°C. The styrene-based resin composition for producing the sheet of this embodiment has been described above. The styrene-based resin composition sheet and the sheet of this embodiment will now be described.

[0074] "Method of manufacturing a styrene-based resin composition sheet" The sheet of the present embodiment contains the styrene-based resin composition. A molded product of the sheet of the present embodiment can be produced using the melt kneading molding machine or by injection molding, injection compression molding, extrusion molding, blow molding, press molding, vacuum molding, foam molding, or the like using pellets of the obtained styrene-based resin composition as a raw material.

[0075] (extruded sheet) A preferred form of styrene-based resin composition sheet of this embodiment is an extruded sheet formed using the above-mentioned styrene-based resin composition of the present invention. The extruded sheet may be either non-foamed or foamed. A commonly known method can be used to produce the 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 sheet take-up device with a uniaxial or biaxial stretching machine. 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.

[0076] -Foam extrusion sheet- In this embodiment, when forming a foamed extruded sheet, materials commonly used for the foaming agent and foam nucleating agent during extrusion foaming can be used. Examples of the foaming agent that can be used include butane, pentane, chlorofluorocarbons, carbon dioxide, and water, with butane being preferred. Examples of the foam nucleating agent that can be used include talc.

[0077] 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 to 300 g / m. 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.

[0078] -Non-foaming 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 viewpoints of rigidity and thermoforming cycle. Furthermore, a uniaxial sheet may be formed by simply stretching at a normal low roll ratio, while a biaxially oriented sheet is preferably formed by stretching about 1.3 to 7 times in the machine direction (MD) with a roll and then stretching about 1.3 to 7 times in the transverse direction (TD) with a tenter in terms of strength. Furthermore, the non-foamed sheet may be multilayered with a styrene-based resin other than the styrene-based resin composition, such as a polystyrene resin. Furthermore, the non-foamed sheet may be multilayered 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.

[0079] <Biaxially oriented sheet> Another aspect of the styrene-based resin composition sheet of this embodiment is a biaxially stretched sheet formed using the above-mentioned styrene-based resin composition. A commonly known method can be used to produce a biaxially stretched sheet. The biaxially stretched sheet can be produced by stretching the sheet in the machine direction (MD) with rolls and then stretching it in the transverse direction (TD) with a tenter. Alternatively, the styrene-based resin composition formed into a plate shape can be heated to a temperature about 10 to 40°C above the Vicat softening temperature of the composition and then sequentially or simultaneously biaxially stretched in a tenter.

[0080] The biaxially stretched sheet of this embodiment is preferably stretched at a ratio of about 1.3 to 7.0 in the MD direction and about 1.3 to 7.0 in the TD direction in terms of strength.

[0081] The average thickness of the biaxially oriented sheet of 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 to ensure the strength, particularly rigidity, of the sheet and container, while 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.

[0082] The orientation relaxation stress in the machine direction and the cross direction of the biaxially stretched sheet of this embodiment is preferably in the range of 0.4 to 1.3 MPa. By adjusting the orientation relaxation stress within this range, the strength of the molded product of the biaxially stretched sheet can be maintained.

[0083] 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 due to 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 oils. The method for applying the antifogging agent to the biaxially stretched sheet of this embodiment is not particularly limited, and examples of convenient methods include application using a roll coater, knife coater, gravure roll coater, etc. Spraying, immersion, etc. may also be used. Furthermore, the biaxially stretched sheet may be surface-treated by corona treatment, ozone treatment, primer treatment, etc. before application to improve the wettability of the surface.

[0084] [Secondary molded product] Another aspect of this embodiment provides a molded article, particularly a food container, formed using the above-described extruded sheet. The biaxially oriented sheet or a multilayer body containing the same can be molded by vacuum forming into, for example, a food container, such as a lid for a boxed lunch or a container for storing prepared foods. <Food containers> The food container of the present invention is formed from the above-mentioned styrene-based resin composition or styrene-based resin composition sheet. A preferred embodiment of the food container of the present invention will now be described with reference to Figures 1 and 2.

[0085] Figure 1 shows an example of a food container 1 according to the present invention, with the lower member of Figure 1 being a perspective view of a food container body 2 that mainly contains noodles or rice bowl-type foods, and the upper member of Figure 1 being a lid 3 that covers an opening 6 of the food container body 2. For ease of explanation, Figure 1 shows the food container body 2 and the lid 3 that can fit into the opening 6 of the food container body 2 as an example of a food container 1 according to this embodiment, but it is sufficient for the food container 1 according to this embodiment to have only the food container body 2. FIG. 2 is a schematic diagram showing a cross section of a mold 9 used to manufacture the food container 1 (particularly the food container body 2) of FIG.

[0086] The shape of a food container 1 of this embodiment and a method for forming the same will be described below with reference to FIG. The food container body 2 of this embodiment has a recess 4 capable of accommodating food. Figure 1 shows a food container 1 having one recess 4 as an example of a recess 4, and a groove 5 is formed around the entire periphery of the inner wall of the food container body 2 so that the amount of contents can be visually confirmed from the outside. The area of ​​the bottom surface of the food container body 2 is smaller than the area of ​​the opening 6. Furthermore, the opening 6 of the food container body 2 is provided with an outwardly protruding edge 7, and the edge 7 can be fitted into the lid 3 that covers the opening 6 of the food container body 2. The shape of the recess 4 is not particularly limited, and may be, for example, a (substantially) cylindrical shape or a polygonal cylindrical shape. The food container in this embodiment may also have multiple recesses 4. An example of a food container having multiple recesses 4 is a shape in which multiple side dishes are separated by partition walls, such as food containers used in commercially available boxed lunches.

[0087] The food container 1 in this embodiment can be produced, for example, using a mold 9 shown in Fig. 2. As an example of this embodiment, an embodiment in which the food container 1 (food container body 2) is integrally molded from a styrene-based resin composition sheet 10 obtained by molding a styrene-based resin composition will be described below with reference to Fig. 2. For example, a styrene-based resin composition sheet 10 having a thickness of 100 to 1000 μm is produced by extrusion molding a styrene-based resin composition. At this time, the surface layer of the styrene-based resin composition sheet 10 may be co-extruded or film-laminated with polystyrene or polypropylene to a thickness of 1 to 100 μm. The resulting styrene-based resin composition sheet 10 is then preheated at 150 to 250°C for 5 to 60 seconds, and the heated styrene-based resin composition sheet 10 is placed in a mold 9 so as to cover the recessed portion 11, and shaped by a predetermined molding method. For example, the recessed portion 11 can be evacuated to form a food container body 2 having a desired shape. Alternatively, the styrene resin composition sheet 10 may be placed so as to cover the recess 11 of the mold 9, and then heated and shaped by a predetermined molding method (e.g., thermocompression molding, vacuum molding, pressure molding, plug-assisted molding).

[0088] As an example of a preferred aspect of this embodiment, the food container 1 (particularly the food container body 2) can be shaped by using the mold 9 to subject a heated styrene-based resin composition sheet 10 to thermocompression molding, vacuum molding, pressure molding or plug-assisted molding. Furthermore, when manufacturing food containers 1 (particularly food container bodies 2) with different depths, the ratio (d / r) of the depth d of the recess to the diameter r of the top surface of the recess (=diameter of the opening) can be changed by using spacers 12. Figure 2 shows, as an example, a state in which spacers 12 are provided in recess 11 of depth d so that the recess has a depth d2 or a depth d1.

[0089] The average thickness (wall thickness) of the food container 1 used in the present invention is 0.05 to 3 mm, preferably 0.1 to 2 mm, and more preferably 0.15 to 1.5 mm. If it is thinner than 0.05 mm, the container will lack rigidity, and if it is thicker than 3 mm, the container will be heavy, increasing material costs and becoming bulky and difficult to dispose of as trash. In this embodiment, the ratio of the depth of the food container to the diameter of the opening (drawing ratio) is preferably 0.1 or more and 1.0 or less. If the drawing ratio is greater than 1.0, uneven thickness occurs, reducing the container's strength. Furthermore, if the depth / diameter ratio is less than 0.1, the container will have a flat shape, making it less likely to have uneven thickness. In addition, oil or oil-containing liquids will remain on the bottom of the food container (especially the outer periphery of the bottom), making it difficult to achieve the oil-resistant effect. On the other hand, if the drawing ratio (depth / diameter ratio) is 0.1 or more and 1.0 or less, not only will it be relatively easy to accommodate contents such as food, but it will also be easier to achieve the oil-resistant effect regardless of the food menu that can be accommodated. In this specification, the opening diameter refers to the diameter when the opening shape is circular, the minor axis when the opening shape is elliptical, and the shortest length of the diagonal when the opening shape is polygonal. In addition, in order to maintain the airtightness of the container, it is preferable to design the top of the container to have an uneven shape to improve fit. The food container used in the present invention has good shape retention due to heat, and therefore has excellent fit.

[0090] The food container of the present invention can be formed by any method, including injection molding, injection compression molding, extrusion molding, blow molding, press molding, thermocompression molding, vacuum molding, pressure molding, plug-assist molding, and foam molding, and is not limited to any particular molding method. For the food container used in the present invention, a method in which the food container is shaped by vacuum molding after sheet (film) molding is preferred, particularly from the standpoints of productivity and cost. The food container according to the present invention is preferably formed from a styrene-based resin composition sheet, and more preferably formed after forming a styrene-based resin composition sheet made from the styrene-based resin composition.

[0091] The styrene-based resin composition sheet used in this embodiment preferably has a thickness of 0.1 to 2 mm, more preferably 0.2 to 1 mm, and even more preferably 0.3 to 0.8 mm. If it is thinner than 0.1 mm, the rigidity of the container will be insufficient when it is made into a container, and if it is thicker than 2 mm, the heating time for vacuum forming will be long, resulting in reduced productivity.

[0092] The surface of the styrene-based resin composition sheet used in the present invention may be laminated with a styrene-based resin or a polyolefin-based resin for smoothness and design. More specifically, the styrene-based resin sheet is a laminate having a first layer containing 70 to 97% by mass of a styrene-based resin (A) and 3 to 30% by mass of a cellulose-based polysaccharide (B) having a lignin content of 10% by mass or less, and a surface layer containing a styrene-based resin or a polyolefin-based resin on the surface of the first layer. In this embodiment, the surface layer may be laminated on one side or both sides of the first layer. The thickness of the surface layer is preferably 1 to 100 μm, which is sufficient to maintain the performance of the food container. In this embodiment, the styrene-based resin used as the material for forming the food container can be the styrene-based resin described below. Polyolefins such as polyethylene, polypropylene, polyvinyl acetate, and polyvinyl alcohol can be used, and copolymers thereof may also be used. Polypropylene is particularly preferred from the viewpoint of oil resistance. Methods for laminating the surface layer onto the first layer include co-extrusion using an extruder and film lamination. The styrene-based resin sheet used in the present invention has excellent adhesion to polyolefins and is characterized by its low peeling when heated, etc.

[0093] [Characteristics of food containers] <Heat mold retention> The food container of this embodiment preferably has heat retention such that it does not deform when left in an oven at 100 to 130°C for 30 minutes.

[0094] <Oil resistance> The oil resistance of the food container of this embodiment is preferably such that the container does not deform when filled with oil such as salad oil and heated in a microwave oven.

[0095] The sheet of this embodiment has excellent vacuum formability and is suitable for use in containers for prepared foods and lunch boxes, containers for microwave ovens, bowls, cups, trays, and the like. [Example]

[0096] Hereinafter, the embodiments of the present invention will be described in more detail based on examples and comparative examples, but the present invention is not limited to these examples in any way.

[0097] <Measurement and evaluation methods> The styrene-based resin composition sheets and food containers obtained in each of the Examples and Comparative Examples were evaluated according to the following methods.

[0098] (1) Evaluation of water contact angle A styrene-based resin composition sheet was prepared by the method described in the Examples and Comparative Examples below, and then a contact angle meter (DropMaster 500, manufactured by Kyowa Interface Science Co., Ltd.) was used to measure the contact angle at three locations one minute after dropping a 2 μL water droplet onto the surface of the sheet, and the average value was used.

[0099] (2) Evaluation of the appearance of the seat The appearance of the sheets produced by the methods described in the Examples and Comparative Examples below was visually inspected according to the following criteria. Criteria for assessing appearance; ◯: No coloring, no lumps, △: Colored, no lumps, ×: Colored, lumps. (3) Evaluation of the odor of the sheet Test pieces were prepared by cutting sheets prepared by the methods described in the Examples and Comparative Examples below into 100 mm x 100 mm x 0.5 mm (thickness), and then the test pieces were placed in plastic bags with zippers and sealed. The plastic bags containing the test pieces were then left to stand at 23°C for 24 hours, after which two people performed a sensory evaluation of the odor using the following criteria. Criteria for odor evaluation; The evaluation was made as follows: ◯: Almost no odor, △: Slight odor, ×: Odor.

[0100] (4) Evaluation of heat retention Food containers prepared by the methods described in the Examples and Comparative Examples below were left in an oven at 120°C for 30 minutes, and the state of the food containers was checked according to the following criteria. ◯: No change, △: Deformation on the bottom of the container, ×: Deformation on the entire container.

[0101] (5) Evaluation of oil resistance Food containers prepared using the methods described in the Examples and Comparative Examples below were filled with 5 ml of salad oil (salad oil manufactured by Nisshin Oillio Co., Ltd.), heated in a 500 W microwave for 2 minutes, and the condition of the food containers was evaluated using the following criteria. ◯: No change, △: The salad oil was visually cloudy, ×: There were holes.

[0102] (6) Evaluation of thermal insulation Food containers prepared by the methods described in the Examples and Comparative Examples below were filled with 50 ml of boiling water and left at 23°C for 30 minutes, after which the temperature of the hot water inside the food container was measured.

[0103] (7) Measurement of the contents of styrene monomer units, methacrylic acid monomer units, and methyl methacrylate monomer units in styrene-based resin (A) Proton nuclear magnetic resonance ( 1 The resin composition was determined from the integral ratio of the spectrum measured by a 1 H-NMR spectrometer. Sample preparation: 30 mg of resin pellets were 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℃, observation nucleus 1 H, 64 accumulations, 11 seconds repetition time.

[0104] (Spectral assignment) Regarding the assignment of the spectrum measured in dimethyl sulfoxide deuterated solvent, the peaks at 0.5 to 1.5 ppm are due to the hydrogen atoms of the α-methyl groups of methacrylic acid, methyl methacrylate, and six-membered cyclic acid anhydrides; the peaks at 1.6 to 2.1 ppm are due to the hydrogen atoms of the methylene groups in the polymer main chain; the peak at 3.5 ppm is due to the hydrogen atoms of the carboxylic acid ester (-COOCH3) of methyl methacrylate; and the peak at 12.4 ppm is due to the hydrogen atoms of the carboxylic acid of methacrylic acid. Furthermore, the peaks at 6.5 to 7.5 ppm are due to the hydrogen atoms of the aromatic ring of styrene. Note that the content of six-membered cyclic acid anhydrides in the resins of the present examples and comparative examples is low, making quantification by this measurement method difficult.

[0105] (8) Melt flow rate (MFR) measurement The melt mass flow rate (g / 10 min) of the styrene-based resin (A) was measured in accordance with ISO 1133 (200° C., load 49 N).

[0106] (9) Measurement of the average length of cellulose polysaccharides (B) Ultrathin sections with a thickness of 75 nm were prepared from test piece (b) prepared by the methods described in the Examples and Comparative Examples below, and photographs were taken at 50,000x magnification using an electron microscope. The photographs were then scanned at a resolution of 200 dpi, and the minimum and maximum lengths of 100 cellulose polysaccharides (B) were measured using particle analysis software on an image analyzer IP-1000 (manufactured by Asahi Kasei Corporation). The arithmetic means were taken as the average minor axis length d1 and the average major axis length d2. Similarly, photographs of cellulose polysaccharide (B) alone were taken at 50,000x magnification using an electron microscope, and the arithmetic means were taken as the average minor axis length d1 and the average major axis length d2.

[0107] (10) Quantitative determination of lignin content The quantitative analysis of lignin in cellulosic polysaccharides (B) was carried out using the TGA method described in the Journal of the Japan Society of Material Cycles and Waste Management, Vol. 22, No. 5, p. 293, 2011. Specifically, a thermogravimetric analyzer, model DTG-60 manufactured by Shimadzu Corporation, was used, and the temperature was raised from room temperature to 900°C at a heating rate of 10°C / min in an air atmosphere. The sample to be analyzed was dried at 70°C for 2 hours, and 3 to 5 mg was precisely weighed, and the weight change due to thermal decomposition was measured. The sample container used was a disc-shaped platinum dish with an inner diameter of 5 mm and a height of 2 mm, and all experiments were performed under fixed conditions.

[0108] (11) Measurement of hemicellulose content The quantitative analysis of hemicellulose in cellulosic polysaccharides (B) is as follows. The dispersion medium was removed from a dispersion of cellulose polysaccharide (B) or a re-dispersion of cellulose polysaccharide (B) obtained by dissolving and removing the resin component from a styrene-based resin composition, and the cellulose residue was recovered and dried at 105°C to obtain a dried sample, and the mass of the dried sample was measured by the following method. The dried cellulose residue was crushed and the resulting crushed sample was extracted with an alcohol (ethanol) / benzene mixed solvent in a Soxhlet extractor for 6 hours. This was followed by an additional 4-hour extraction with an alcohol (ethanol) / benzene mixed solvent to obtain a defatted sample. 2.5 g of the defatted sample was mixed with 150 mL of distilled water, 1.0 g of sodium chlorite, and 0.2 mL of acetic acid and heated at 70-80°C for 1 hour. Another 1.0 g of sodium chlorite and 0.2 mL of acetic acid were added and heated at 70-80°C for 1 hour. This procedure was repeated 3-4 times until the sample was decolorized to white. The resulting sample was filtered, washed with water and acetone, and dried at 105°C to obtain a holocellulose fraction (the total amount of α-cellulose and hemicellulose). The mass of this holocellulose fraction was measured. Next, 25 mL of 17.5% by weight sodium hydroxide solution was added to 1.0 g of the holocellulose fraction. After 3 minutes, the mixture was lightly crushed with a glass rod until swollen. The mixture was then allowed to stand at 20°C. 30 minutes after the addition of the sodium hydroxide solution, 25 mL of distilled water was added, stirred for exactly 1 minute, allowed to stand at 20°C for 5 minutes, and then filtered through a glass filter to wash the filtrate until neutral. Further, 40 mL of 10% by weight acetic acid was added by suction filtration, followed by suction filtration of 1 L of boiling water. The washed sample was then dried at 105°C until a constant mass was obtained, yielding an α-cellulose fraction. The mass of this α-cellulose fraction was measured. The hemicellulose content was calculated from the masses of the holocellulose fraction and the α-cellulose fraction obtained as described above using the following formula. Holocellulose (%) = holocellulose fraction (g) / sample (anhydrous basis) (g) × 100 α-Cellulose (%) = α-cellulose fraction (g) / sample (anhydrous basis) (g) × 100 Hemicellulose (%) = Holocellulose (%) - (α-cellulose (%))

[0109] The materials used in the examples and comparative examples are as follows. [Styrene-based resin (A)] (GPPS-1) Polystyrene with MFR 7.8 (GPPS, manufactured by PS Japan, HF77) was used. (HIPS-1) Polystyrene with MFR 3.0 (HIPS, manufactured by PS Japan, HT478) was used. (HIPS-2) Polystyrene with MFR 2.0 (HIPS, manufactured by PS Japan, 475D) was used. (Copolymerization-1) A polymerization raw material composition liquid consisting of 70.0 parts by mass of styrene (ST), 15.0 parts by mass of butyl methacrylate (BA), 15.0 parts by mass of ethylbenzene, and 0.025 parts by mass of 1,1-bis(t-butylperoxy)cyclohexane was continuously supplied at a rate of 1.1 L / hour to a 4-L complete mixing reactor, then to a polymerization apparatus consisting of a 2-L laminar flow reactor, and further to a devolatilizer connected to a single-screw extruder that removes volatile components such as unreacted monomers and polymerization solvent, to prepare a styrene copolymer resin, Copolymer-1. The polymerization reaction conditions in the polymerization step were a polymerization temperature of 122°C for the complete mixing reactor and a polymerization temperature of 120 to 142°C for the laminar flow reactor. The devolatilized unreacted gas was condensed in a condenser through which a -5°C refrigerant was passed, and recovered as an unreacted liquid. The polymer content in the final polymerization solution was measured by 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, and was found to be 65.6 mass%, with an MFR of 4.6. (Blend-1) The HIPS-2 (475D) was blended with 5% by mass of an SMA copolymer (XIBOND250, manufactured by POLYSCOPE), and the MFR was 3.2.

[0110] [Cellulosic polysaccharides (B)] Cellulose fiber-1 (manufactured by Celite Co., Ltd., SW-10, d1: 20 μm, d2: 700 μm, lignin content: 0.5% by mass, hemicellulose content: 11% by mass) Cellulose fiber-2 (manufactured by Celite, SW-30, d1: 60 μm, d2: 700 μm, lignin content 0.5% by mass, hemicellulose content 15% by mass) CNF: Cellulose nanofiber (manufactured by Chuetsu Pulp Co., Ltd., CNF-10, d1: 35 nm, d2: approximately 1 μm, lignin content 0 mass%, hemicellulose content 15 mass%) Wood flour (Naga Wood Co., Ltd., raw material: cedar, d1: 120 μm, d2: 180 μm, lignin content 23% by mass, hemicellulose content 18% by mass)

[0111] [Dispersant (C)] Fatty acid ester: Glycerin monostearate (Riken Vitamin Co., Ltd.: S-100) Terpene: Aromatic modified terpene resin (Yasuhara Chemical Co., Ltd.: YS Resin TO-105)

[0112] [Compatibilizer (D)] Maleic anhydride-modified SEBS (Asahi Kasei Corporation, Tuftec M1913, MFR5, S / EB=30 / 70)

[0113] [Additives] (phenolic antioxidant) 3-(3,5-di-tert-butyl-4-hydroxyphenyl) stearyl propionate (BASF, Irganox 1076) (phosphorus antioxidant) Tris(2,4-di-tert-butylphenyl)phosphite (BASF, Irgafos168)

[0114] [Examples 1 to 12] A styrene-based resin composition, a precursor of a sheet, was prepared by blending a styrene-based resin (A) and a cellulose-based polysaccharide (B) in the composition ratios shown in Table 1. To prepare the premix, 0.2 parts by mass each of Irganox 1076 and Irgafos 168 were added as antioxidants to 100 parts by mass of components (A) and (B). In some examples, 10 parts by mass of dispersant (C) was added as needed. The resulting premix was mixed together and melt-extruded at 180°C to 220°C using a twin-screw extruder (Toshiba Machine Co., Ltd., TEM-26SS) to obtain resin pellets of the styrene-based resin composition as a kneaded product. The screw rotation speed was 150 rpm, and the extrusion rate was 10 kg / hr. The obtained resin pellets were used to prepare non-foamed extruded sheets. For the non-foamed extruded sheets, a 25 mm diameter single-screw sheet extruder manufactured by Soken Co., Ltd. was used to prepare styrene resin composition sheets with a thickness of approximately 0.5 mm, with the resin melting zone temperature set to 180-200°C. Furthermore, for Example 10, GPPS (680 manufactured by PS Japan Co., Ltd.) was co-extruded on both sides, and for Example 11, PP (E-100GV manufactured by Prime Polymer Co., Ltd.) was co-extruded to a thickness of approximately 0.1 mm to prepare laminated sheets. The obtained styrene-based resin composition sheet was used to produce a food container with the shape shown in Figure 1. For the food container, a sheet container forming machine manufactured by Soken Co., Ltd. was used, and the heating zone was set to 200°C to produce a container with a drawing ratio of 75% represented by the following formula (1), and vacuum forming was performed. The evaluation results are shown in Table 1. The formula (1) representing the drawing ratio is as follows: Squeeze ratio = depth of food container ÷ diameter of opening of food container (maximum diameter) × 100 Formula (1) The resin pellets were molded into test pieces (b) using an injection molding machine manufactured by The Japan Steel Works, Ltd., equipped with an ISO standard test piece type mold (b) measuring 50 x 120 mm and 1 mm thick, at a cylinder temperature of 220°C, a mold temperature of 50°C, an injection pressure (gauge pressure 40-60 MPa), an injection speed (panel setting value) of 50%, and an injection time / cooling time of 5 seconds / 20 seconds. The average length of the cellulose polysaccharide (B) was measured using the test pieces (b) obtained.

[0115] [Comparative Examples 1 to 9] Precursor compositions for the sheets described in Comparative Examples 1 to 9 were prepared in the same manner as in Example 1, except that the compositions were changed as shown in Table 2. The results of measurement and evaluation of each physical property are shown in Table 2.

[0116] [Table 1]

[0117] [Table 2]

[0118] As shown in Table 1, Examples 1 to 12 are excellent in heat resistance, oil resistance, heat insulation, and moldability. As shown in Table 2, Comparative Examples 1 to 9 are deformed at high temperatures and develop holes in a microwave oven, resulting in poor heat resistance and oil resistance. When there is a large amount of cellulose fiber, as in Comparative Example 5, it is not possible to produce a product by vacuum molding. When wood flour is used, as in Comparative Example 7, the product suffers from severe discoloration and odor, and the oil resistance is also poor due to the development of holes. [Industrial Applicability]

[0119] The present invention provides a styrene-based resin composition sheet that reduces the environmental load, has excellent oil resistance and heat insulation properties, and is less odorous and discolored. Molded articles obtained from the styrene-based resin composition sheet of the present invention can be suitably used for food containers such as trays, cups, bowls, and lids.

Claims

1. A styrene-based resin composition sheet containing a styrene-based resin composition composed of a styrene-based resin (A) and a cellulose-based polysaccharide (B) having a lignin content of 10 mass% or less, and a compatibilizer (D), the styrene-based resin (A) is polystyrene, a rubber-modified styrene-based resin in which particles of a rubber-like polymer (a1) are dispersed in a polymer matrix phase composed of a styrene-based polymer containing a styrene-based monomer unit, a styrene-based copolymer resin having a styrene-based monomer unit, or a mixture thereof, and the content of the styrene-based resin (A) is 70.0 to 97.0 mass% based on the total amount of the styrene-based resin composition; the content of the cellulose polysaccharide (B) is 3 to 30 mass% based on the total amount of the styrene-based resin composition, the compatibilizer (D) is a rubber-like polymer (a2), and the content of the compatibilizer (D) is 0.5 to 10.0 parts by mass per 100 parts by mass of the total amount of the styrene-based resin composition; a total content of the rubber-like polymer (a1) and the rubber-like polymer (a2) contained in the styrene-based resin composition sheet is 3 to 20% by mass relative to the total amount (100% by mass) of the styrene-based resin composition sheet; A styrene-based resin composition sheet having a surface with a contact angle with water in the range of 50° to 105°.

2. The styrene-based resin composition sheet according to claim 1, wherein the amount of hemicellulose in the cellulosic polysaccharide (B) is 1% by mass or more.

3. A styrene-based resin composition sheet as described in claim 1 or 2, wherein the styrene-based resin composition sheet further contains a dispersant (C), and the content of the dispersant (C) is 0.5 to 10.0 mass% relative to the total amount (100 mass%) of the styrene-based resin composition sheet.

4. 4. The styrene-based resin composition sheet according to claim 3, wherein the dispersant (C) is one or more compounds selected from the group consisting of fatty acid ester-based compounds, polyethylene glycol-based compounds, terpene-based compounds, and rosin-based compounds.

5. 3. The styrene-based resin composition sheet according to claim 1, wherein the compatibilizer (D) is a maleic anhydride-modified styrene-based rubber polymer.

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