JP2023095312A - Styrenic resin composition sheet - Google Patents

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

The present invention relates to a styrene-based resin composition sheet.

Styrenic resins are used in a wide range of applications due to their excellent moldability, dimensional stability, and transparency. In addition, biomass materials have attracted attention from the viewpoint of environmental protection, and composite materials of resin materials and naturally-derived organic fillers or biopolymers are being studied.
For example, Patent Literatures 1 and 2 disclose a styrenic composite resin composition comprising a styrenic resin and a cellulose material. Further, Patent Document 3 discloses a composition comprising a styrene resin and modified nanocellulose (hereinafter also referred to as CNF).

JP-A-7-173352 JP-A-8-231795 JP 2016-176052 A

However, in the techniques of Patent Documents 1 and 2, wood flour, pulp, or the like is used as the cellulosic material, but the application and effects of the sheet compact are not studied at all. Because it contains a lot of lignin, it is difficult to use because of its bad odor and coloration. In addition to the high cost of the ABS resin used in the technique of Patent Document 3, the molding temperature is slightly high, and the cellulosic material is partly carbonized depending on the molding conditions or the unmodified cellulose material. There are issues such as

Accordingly, an object of the present disclosure is to provide a styrene-based resin composition sheet that reduces environmental load, is excellent in oil resistance and heat insulation, and has little odor and coloration.

In view of the above problems, the present inventors have conducted intensive research and repeated experiments. As a result, the cellulose-based polysaccharide (B ) from 3 to 30% by mass, the present inventors have found that the above problems can be solved, and have completed the present invention.
That is, the present invention is as follows [1] to [5].

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

According to the present invention, it is possible to provide a styrene-based resin composition sheet that reduces environmental load, is excellent in oil resistance and heat insulation, and has little odor and coloration.

FIG. 1 shows an example of a container using the styrene-based resin composition sheet of this embodiment. FIG. 2 shows an example of a method for manufacturing a container using the styrene-based resin composition sheet of this embodiment.

Hereinafter, embodiments of the present invention (hereinafter referred to as "present embodiments") will be described in detail. can be implemented.
[Styrene resin composition sheet]
The styrene resin composition sheet according to the present embodiment includes 70.0 to 97.0% by mass of styrene resin (A) and 3 to 30% by mass of cellulose polysaccharide (B) having a lignin content of 10% by mass or less. %. In other words, the styrene-based resin composition sheet may contain the styrene-based resin (A) and the cellulose-based polysaccharide (B) in predetermined amounts. A styrenic resin composition containing (B) may be used as a raw material for the main component, or the styrenic resin (A) and the cellulose polysaccharide (B) may be separated from each other without going through the styrenic resin composition. They may be blended and directly formed into a sheet.
In addition, the styrene resin composition sheet according to the present embodiment may further contain a dispersant (C), a compatibilizer (D) and an optional additive component if necessary. The styrene-based resin composition sheet according to the embodiment includes 70.0 to 97.0% by mass of styrene-based resin (A) and 3 to 30% by mass of cellulose-based polysaccharide (B) having a lignin content of 10% by mass or less. and optionally added dispersant (C) 0.5 to 10% by mass, compatibilizer (D) 0.5 to 10% by mass, and optional additive component 0 to 5% by mass. .
In this specification, the “main component” refers to a component that accounts for the largest mass ratio in the material constituting the sheet, and is preferably 55% by mass or more and 100% by mass or less, and 70% by mass. 100% by mass or less is more preferable, and 90% by mass or more and 100% by mass or less is even more preferable.
The shape or thickness of the styrene-based resin composition sheet in the present embodiment is not particularly limited, and the shape and thickness can be appropriately changed according to the desired size according to the purpose. For example, the average thickness of the styrene resin composition sheet in the present embodiment is preferably 0.1 to 2 mm, more preferably 0.2 to 1 mm, still more preferably 0.3 to 0.8 mm. be. If the sheet has an average thickness of less than 0.1 mm, its rigidity will be insufficient when it is formed into a food container.
In addition, in this specification, the average thickness of the styrene-based resin composition sheet is calculated with a thickness meter.

The surface of the styrene-based resin composition sheet in the present embodiment has 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. may be coated with Lamination with the resin film can be performed on one side or both sides of the styrene-based resin composition sheet. The styrene resin (A) described later can be used as the styrene resin (A). As the polyolefin resin, polyethylene, polypropylene, polyvinyl acetate, polyvinyl alcohol and the like are used, and they may be copolymers. In particular, it is preferable from the viewpoint of oil resistance to laminate a polypropylene resin layer on at least one surface of the styrene-based resin composition sheet in the present embodiment. Examples of the lamination method using the resin film include methods such as co-extrusion using an extruder and film lamination. The styrene-based resin composition sheet that can be used in the present invention is characterized by excellent adhesiveness to polyolefin-based resins and less peeling due to heating or the like.

Moreover, if necessary, the surface of the styrene-based resin composition sheet of the present embodiment may be surface-treated. Examples of the surface treatment include degreasing treatment, UV ozone treatment, blasting treatment, polishing treatment, plasma treatment, corona discharge treatment, laser treatment, etching treatment and flame treatment. Thereby, the surface condition of the styrene-based resin composition sheet can be adjusted. Specifically, the surface treatment facilitates adjustment of the contact angle with water on the surface of the styrene-based resin composition sheet of the present embodiment to a range of 50° to 105°.
The upper degreasing treatment is a method of removing dirt such as oil on the surface by dissolving it in an organic solvent such as acetone or hexane. The UV ozone treatment is a method of cleaning or modifying the surface using short-wave ultraviolet rays emitted from a low-pressure mercury lamp and ozone (O ₃ ) generated by the ultraviolet rays. The blasting treatment is a treatment of spraying various fine particles onto the surface, and includes wet blasting treatment, shot blasting treatment, sandblasting treatment, and the like. The polishing treatment includes buffing using an abrasive cloth, roll polishing using sandpaper, electropolishing, and the like. The plasma treatment is a method of generating a plasma beam with a high-voltage power supply and a rod and irradiating the surface with the beam to excite and functionalize surface molecules. The above corona discharge treatment is mainly used for surface modification of resins, etc., and electrons emitted from the electrode cut the polymer main chain or side chain on the surface of the resin. This is a method of forming a polar group. The laser treatment is a method of roughening the surface by rapidly heating and cooling the surface by laser irradiation. Examples of the etching treatment include chemical etching treatments such as an alkali method, a phosphoric acid-sulfuric acid method, a fluoride method, a chromic acid-sulfuric acid method, and an iron chloride method. The flame treatment is a method for making the surface hydrophilic by burning a mixed gas of a combustion gas and air to convert oxygen in the air into plasma, and then applying the plasma-generated oxygen to the surface.

When the contact angle with water on the surface of the styrene 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 periphery of various rolls, ink, Adhesive components, metal powders, various resins, etc. may be difficult to adhere to the roll.
The contact angle with water on the surface of the styrene resin composition sheet of the present embodiment is preferably in the range of 50° to 105°, more preferably in the range of 75° to 100°, still more preferably in the range of 80° to 95°. Range. In order to make the water contact angle within the above range, lamination with the aforementioned resin film or surface treatment may be performed.

In the present embodiment, the following six methods (a) to (f) can be used to control the contact angle with water on the surface of the styrene-based resin composition sheet within the range of 50° to 105°.
(a) a styrene resin (A) (hereinafter also referred to as component (A)) and a cellulose polysaccharide (B) having a lignin content of 10% by mass or less (hereinafter also referred to as component (B)) and are blended in predetermined amounts. Specifically, by blending 70.0 to 97.0% by mass of component (A) and 3 to 30% by mass of component (B), the hydrophobic-hydrophilic material balance of the styrene resin composition sheet easy to secure.
(b) Dispersing agent (C) (hereinafter also referred to as component (C)), which is an optional component, and compatibilizer (D) (hereinafter also referred to as component (D)) are blended in predetermined amounts. is preferred. Specifically, by blending 0.5 to 10% by mass of component (C) and 0.5 to 10% by mass of component (D), the dispersibility of each component constituting the styrene resin composition sheet is improved. and improve 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% by mass with respect to the total amount of the sheet. Thereby, the dispersibility of each component constituting the styrene-based resin composition sheet is improved, and the surface smoothness is improved.
Known lubricants can be used without any particular limitation as the lubricant. Examples include fatty acids, fatty acid esters, fatty acid amides, and mixtures thereof. Examples of the fatty acid include lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, behenic acid, erucic acid, and elaidic acid. preferable. In addition, the fatty acid may be contained in the form of a salt such as a metal salt.
Examples of the fatty acid ester include esters of various fatty acids, such as butyl myristate, butyl palmitate, butyl stearate, neopentyl glycol dioleate, sorbitan monostearate, sorbitan distearate, sorbitan tristearate, and oleic acid. Oleyl, isocetyl stearate, isotridecyl stearate, octyl stearate, isooctyl stearate, amyl stearate, butoxyethyl stearate and the like.
Examples of the fatty acid amide 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 to surface-treat the surface of the styrene-based resin composition sheet of the present embodiment. The surface treatment is as described above, and one or more 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. is preferably
(e) The surface of the styrene resin composition sheet is preferably coated with a styrene resin (A) or polypropylene resin layer (average thickness 2 to 200 μm) to form a laminate. As a result, the surface of the styrene-based resin composition sheet can be coated with a hydrophobic material, so that the contact angle with water can be easily controlled within the range of 50° to 105°. The method for laminating the polypropylene resin layer is preferably the method described above or in the examples.
(f) The heating temperature during (extrusion) molding in sheet molding is preferably 220° C. or less. As a result, aggregation of the cellulose component in the cellulose-based polysaccharide (B) having a lignin content of 10% by mass or less or thermal deterioration of the cellulose component can be suppressed or prevented, so the hydrophobic-hydrophilic material balance can be controlled.
In addition, the method for measuring the water contact angle in this specification is measured using the method described in the section of Examples below.

Hereinafter, after describing the aspect in which the styrene-based resin composition sheet according to the present embodiment is formed using the styrene-based resin composition as a main component, the characteristics of the sheet and the food container formed from the sheet will be described. As described above, the styrene-based resin composition sheet can be molded without using a styrene-based resin composition. When the styrene-based resin composition sheet does not use the styrene-based resin composition as a raw material, the styrene-based resin (A) and the cellulose-based polysaccharide having a lignin content of 10% by mass or less ( B), as well as the dispersant (C), compatibilizer (D), and optional additive components that are added as necessary, refer to the contents described in the following section of the styrene resin composition.

(Styrene resin composition)
The styrene resin composition forming the styrene resin composition sheet of the present embodiment contains 70 to 97% by mass of the styrene resin (A) and a cellulose polysaccharide (B) having a lignin content of 10% by mass or less. ) is preferably contained in an amount of 3 to 30% by mass. By containing predetermined amounts of a styrene resin (A) and a cellulose polysaccharide (B) as the styrene resin composition, which is the main component of the styrene resin composition sheet in the embodiment, environmental load is reduced, It has excellent oil resistance and heat insulation, and has the effect of being less odorous and less colored. By including the cellulose-based polysaccharide (B), it is possible to improve the oil resistance and heat insulating properties, which were problems of the styrene-based resin (A). From the viewpoint of moldability, it is desirable to use a composition containing the styrene resin (A) as the main component.
Moreover, the styrenic resin composition of the present embodiment may further contain a dispersant (C), a compatibilizer (D) and optional additive components, if necessary.

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

It is preferable that the MFR (200° C., 5 kg) of the styrene-based resin (A) in the present invention is 2 (g/10 minutes) or more. Preferably 5 (g/10 min) or more, more preferably 8 (g/10 min) or more and 30 (g/10 min) or less, still more preferably 10 (g/10 min) to 25 (g/10 min) ) below. This is because melt-mixing at 240° C. or less is necessary to prevent coloring and burning of the cellulose-based polysaccharide (B). It should be noted that the MFR in this specification is a value measured according to ISO 1133.
Furthermore, the styrene resin (A) preferably contains an unsaturated carboxylic acid monomer unit in order to improve adhesion with the cellulose polysaccharide (B) and improve vacuum moldability. The content of the unsaturated carboxylic acid-based monomer unit is preferably 2.0 to 16.0% by mass, more preferably 4 to 14% by mass, more preferably 4 to 14% by mass, based on the total styrene resin (A). is 8 to 13% by mass.
The styrenic resin (A) to be used may be used singly or in combination of two or more.

The styrene-based resin (A) that can be used in the present embodiment is preferably a polymer having styrene-based monomer units, more preferably a copolymer having styrene-based monomer units. The styrene resin (A) contains a styrene monomer and at least one monomer selected from other vinyl monomers and rubber-like polymers copolymerizable with the styrene monomer. More preferably, it is a styrene-based copolymer resin obtained by polymerization. The styrenic resin (A) in the present invention is not particularly limited. Modified styrenic resins, styrenic copolymer resins having styrenic monomer units, or mixtures thereof may be mentioned.

<<Polystyrene>>
In the present embodiment, polystyrene is a homopolymer obtained by polymerizing styrene-based monomers, and commonly available materials can be appropriately selected and used. Styrenic monomers constituting polystyrene include, in addition to styrene, α-methylstyrene, α-methyl-p-methylstyrene, ο-methylstyrene, m-methylstyrene, p-methylstyrene, vinyltoluene, ethyl Styrene, isobutylstyrene, and styrene derivatives such as t-butylstyrene or bromostyrene and indene. Styrene is particularly preferred from an industrial point of view. These styrenic monomers can be used singly or in combination of two or more. Polystyrene may contain further monomer units other than the above styrene monomer units as long as the effect of the present invention is not impaired, but typically consists of styrene monomer units.

<<Rubber-modified styrene resin>>
In the present embodiment, the rubber-modified styrene resin is obtained by dispersing particles of the rubber-like polymer (a1) (also referred to as rubber-like polymer particles (a1)) in a styrene resin as a polymer matrix phase. , by polymerizing a styrenic monomer in the presence of the rubber-like polymer (a1).

-Polymer matrix phase-
The styrenic monomer constituting the polymer matrix phase of the rubber-modified styrenic resin of the present embodiment is the same as the styrenic monomer constituting the above-described polystyrene, and therefore is omitted.
The polymer matrix phase of the rubber-modified styrenic resin of the present embodiment is preferably composed of a styrenic polymer containing styrenic monomer units. The monomer unit constituting the styrene polymer of the present embodiment is a styrene monomer unit and/or a vinyl monomer unit (i) copolymerizable with the styrene monomer. is preferred. Therefore, the styrenic polymer is preferably one or more selected from the group consisting of the polystyrene and the styrenic copolymer resin described below. Examples of the styrene-based copolymer resin include styrene-(meth)acrylic acid ester copolymers, as described later.
The term "constituted" means that 50% by mass or more, preferably 70% by mass or more, more preferably 90% by mass or more of the total amount of the polymer matrix phase is occupied by the styrenic polymer.
Among the monomer units constituting the styrenic polymer of the present embodiment, the content of the styrenic monomer unit is preferably 50 to 100% by mass, more preferably 60% with respect to the entire styrenic polymer. ~100% by mass, more preferably 70 to 100% by mass, even more preferably 80 to 100% by mass, and even more preferably 90 to 100% by mass. The content of the styrene monomer unit in the styrene polymer and the vinyl monomer unit (i) copolymerizable with the styrene monomer other than the styrene monomer unit is, respectively, the proton nucleus It can be determined from the integral ratio of the spectrum measured by a magnetic resonance ( ¹ H-NMR) measuring instrument.

In the present embodiment, the vinyl-based monomer (i) is one or more selected from the group consisting of unsaturated carboxylic acid monomers and unsaturated carboxylic acid ester monomer units. are preferred and not particularly limited, but for example, (meth) acrylic acid, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, cyclohexyl (meth) acrylate etc. These monomers can be used individually by 1 type or in combination of 2 or more types.
The term "(meth)acrylic acid" includes both acrylic acid and methacrylic acid.

-Rubber-like polymer particles (a1)-
The rubber-like polymer particles (a1) contained in the rubber-modified styrenic resin of the present embodiment may include, for example, a styrenic polymer obtained from the above styrenic monomer inside, and/or , may be grafted with a styrenic polymer on the outside.

Materials for the rubber-like polymer (a1) or rubber-like polymer particles (a1) of the present embodiment include, for example, polybutadiene, polybutadiene containing polystyrene, polyisoprene, natural rubber, polychloroprene, and styrene-butadiene copolymer. , acrylonitrile-butadiene copolymers, etc. can be used, but polybutadiene or styrene-butadiene copolymers are preferred. Both high cis polybutadiene with a high cis content and low cis polybutadiene with a low cis content can be used for the polybutadiene. Both a random structure and a block structure can be used as the structure of the styrene-butadiene copolymer. One or more of these rubber-like polymers (a1) can be used. Saturated rubber obtained by hydrogenating butadiene rubber 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), AES resin ( acrylonitrile-ethylene propylene rubber-styrene copolymer) and the like.

In the present embodiment, when the rubber-modified styrene-based resin is a HIPS-based resin, particularly preferred among these rubber-like polymers (a1) are high cis-polybutadiene. In the high-cis polybutadiene, the vinyl 1,2 bond is preferably 6 mol % or less, particularly preferably 3 mol % or less.
The content of isomers having a cis 1,4, trans 1,4, or vinyl 1,2 structure as isomers related to the structural units of the high-cis polybutadiene was measured using an infrared spectrophotometer and measured by the Morero method. It can be calculated by data processing.
The high-cis polybutadiene can be easily obtained by polymerizing 1,3-butadiene using a known production method, for example, a catalyst containing an organoaluminum compound and a cobalt or nickel compound.

In the present embodiment, the content of the rubber-like polymer (a1) contained in the rubber-modified styrene-based resin (not including the encapsulated styrene-based polymer) is , preferably 2 to 10% by mass, more preferably 3 to 8% by mass. If the content of the rubber-like polymer (a1) is less than 2% by mass, the impact resistance of the styrene-based resin may decrease. Moreover, when the content of the rubber-like polymer (a1) exceeds 10% by mass, the appearance of the molded product may deteriorate.
In the present disclosure, the content of the rubber-like polymer (a1) contained in the rubber-modified styrenic resin is a value calculated using pyrolysis gas chromatography.
Similarly, the content of the total rubber-like polymer present in the styrene-based resin composition sheet is the amount of the so-called rubber component (conjugated diene-based polymer) contained in the rubber-modified styrene-based resin (rubber-like polymer ( a1)) and the amount of the rubber component (rubber-like polymer (a2)) derived from the elastomer (compatibilizer (D)) added if necessary, and is the total amount of the rubber-like polymer particles (a1). The amount of the styrenic polymer (so-called polymer matrix phase) included is not included.

In the present embodiment, the average particle size of the rubber-like polymer particles (a1) contained in the rubber-modified styrenic resin is preferably 0.5 to 2.5 μm, more preferably 0.5 to 2.5 μm from the viewpoint of impact strength. 0.8 to 2.0 μm.
In the present disclosure, the average particle size of the rubber-like polymer particles (a1) contained in the rubber-modified styrenic resin can be measured by the following method.
A 75 nm-thick ultra-thin section is prepared from a rubber-modified styrenic resin stained with osmium tetroxide, and photographed at a magnification of 10,000 using an electron microscope. In the photograph, particles dyed black are rubber-like polymer particles (a1). From the picture, the following formula (N1):
Average particle size = ΣniDri ³ /ΣniDri ² (N1)
(In the above formula (N1), ni is the number of rubber-like polymer particles (a1) particles having a particle diameter Dri, and the particle diameter Dri is a particle diameter calculated as a circle-equivalent diameter from the area of the particles in the photograph. be.)
The area-average particle size is calculated by the method and taken as the average particle size of the rubber-like polymer particles (a1). For this measurement, a photograph is loaded into a scanner at a resolution of 200 dpi and measured using particle analysis software of an image analyzer IP-1000 (manufactured by Asahi Kasei Corporation).

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

In the present embodiment, the method for producing the rubber-modified styrenic resin is not particularly limited, but in the presence of the rubber-like polymer (a1), bulk polymerization ( or solution polymerization), or bulk-suspension polymerization that shifts to suspension polymerization during the reaction, or emulsion graft polymerization that polymerizes a styrene-based monomer in the presence of a rubber-like polymer (a1) latex. can be done. In bulk polymerization, a mixed solution containing a rubber-like polymer (a1) and a styrenic monomer, and optionally an organic solvent, an organic peroxide, and/or a chain transfer agent is added to a complete mixing reactor. Alternatively, it can be produced by continuously supplying to a polymerization apparatus constructed by connecting a tank reactor and a plurality of tank reactors in series.

<<Styrene-based copolymer resin>>
In the present embodiment, the styrene copolymer resin is a resin optionally containing styrene monomer units, unsaturated carboxylic acid monomer units, and unsaturated carboxylic acid ester monomer units. In the styrene copolymer resin of the present invention, when the total content of styrene monomer units, unsaturated carboxylic acid monomer units, and unsaturated carboxylic acid ester monomer units is 100% by mass, The content of styrenic monomer units is preferably 69 to 98% by mass, more preferably 74 to 96% by mass, still more preferably 77 to 92% 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 allow desired amounts of unsaturated carboxylic acid-based monomer units and optional unsaturated carboxylic acid ester-based monomer units to be described later. It becomes difficult to obtain the effect described later by the monomer unit of.

In the styrene-based copolymer resin of the present embodiment, the unsaturated carboxylic acid-based monomer unit plays a role of improving heat resistance. When the total content of styrene-based monomer units, unsaturated carboxylic acid-based monomer units, and unsaturated carboxylic acid ester-based monomer units in the styrene-based copolymer resin is 100% by mass, unsaturated carboxylic acid The content of acid monomer units is preferably 2 to 16% by mass, more preferably 4 to 14% by mass, still more preferably 8 to 13% by mass. By setting the content to 2% by mass or more, the dispersibility of cellulose can be improved, and the light transmittance, appearance, and heat resistance can be further improved. On the other hand, by setting the content to 16% by mass or less, the fluidity and mechanical properties of the resin can be improved.

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

In the styrene-based copolymer resin of the present embodiment, when the total content of the styrene-based monomer unit, the unsaturated carboxylic acid-based monomer unit, and the unsaturated carboxylic acid ester-based monomer unit is 100% by mass , the content of unsaturated carboxylic acid ester-based monomer units is preferably 0 to 15% by mass, more preferably 1 to 12% by mass, and still 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. In addition, by setting the content of the unsaturated carboxylic acid ester-based monomer unit to 0% by mass, it is possible to improve heat resistance and reduce costs, but from the above viewpoint, the unsaturated carboxylic acid ester-based monomer The body unit content can also be greater than 0% by weight.
When an unsaturated carboxylic acid-based monomer and an unsaturated carboxylic acid ester-based monomer unit are bonded side by side, if a high-temperature, high-vacuum devolatilization apparatus is used, a dealcoholization reaction may occur depending on the conditions. Six-membered cyclic anhydrides may be formed. Although the copolymer resin of the present embodiment may contain this six-membered cyclic anhydride, it is preferable that the amount of the six-membered cyclic anhydride produced is as small as possible because it reduces fluidity.

In the present embodiment, styrene monomer units (e.g., styrene monomer units), unsaturated carboxylic acid-based monomer units (e.g., methacrylic acid monomer units) and unsaturated The content of the carboxylic acid ester-based monomer unit (eg, methyl methacrylate monomer unit) can be determined from the integral ratio of the spectrum measured with a proton nuclear magnetic resonance ( ¹ H-NMR) spectrometer. .

In the present embodiment, the styrene copolymer resin includes styrene monomer units, unsaturated carboxylic acid monomer units, and monomer units other than the optional unsaturated carboxylic acid ester monomer units. is not excluded as long as it does not impair the effects of the present invention. However, the copolymer resin in the present invention is typically preferably composed of styrene-based monomer units, unsaturated carboxylic acid-based monomer units, and unsaturated carboxylic acid ester-based monomer units. .

Examples of the styrene-based monomer constituting the styrene-based copolymer resin of the present embodiment include, but are not limited to, styrene, α-methylstyrene, α-methyl-p-methylstyrene, Styrene derivatives such as ο-methylstyrene, m-methylstyrene, p-methylstyrene, vinyltoluene, ethylstyrene, isobutylstyrene, t-butylstyrene, bromostyrene, and indene. As the styrene-based monomer, styrene is preferable from an industrial point of view. These styrenic monomers can be used singly or in combination of two or more.

The unsaturated carboxylic acid-based monomer constituting the styrene-based copolymer resin of the present embodiment is not particularly limited, but examples thereof include methacrylic acid, acrylic acid, maleic anhydride, maleic acid, fumaric acid, and itaconic acid. be done. As the unsaturated carboxylic acid-based monomer, methacrylic acid is preferable because it has a large effect of improving heat resistance and is liquid at room temperature and excellent in handleability. These unsaturated carboxylic acid-based monomers can be used singly or in combination of two or more.

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

Examples of the styrene-based copolymer resin of the present embodiment include styrene-methyl (meth)acrylate copolymer, styrene-ethyl (meth)acrylate copolymer, styrene-propane (meth)acrylate copolymer, or styrene -Butyl (meth)acrylate copolymer, styrene-methyl (meth)acrylate-butyl methacrylate copolymer, and styrene-methyl (meth)acrylate-methacrylic acid copolymer are preferred.

In the present embodiment, the weight average molecular weight (Mw) of the styrenic copolymer resin is preferably 100,000 to 350,000, more preferably 120,000 to 300,000, still more preferably 140,000 to 240. , 000. When the weight-average molecular weight (Mw) is from 100,000 to 350,000, a resin having excellent balance between mechanical strength and fluidity can be obtained, and gel matter is less mixed. The weight average molecular weight (Mw) is a value obtained by standard polystyrene conversion using gel permeation chromatography.

As the styrene resin (A) of the present embodiment, a mixture obtained by blending one or more of the rubber-modified styrene resins and one or more of the styrene copolymer resins may be used. good. In that case, the mixing ratio of the rubber-modified styrenic resin and the styrenic copolymer resin can be appropriately changed according to the purpose of use. For example, in a system in which the rubber-modified styrene resin is less than the styrene copolymer resin, the styrene copolymer resin is contained in an amount of 0.1 to 30% by mass with respect to the total amount (100% by mass) of the styrene resin (A). preferably. On the other hand, in a system in which the rubber-modified styrene resin is more than the styrene copolymer resin, the styrene copolymer resin is contained in an amount of 70 to 99.9% by mass with respect to the total amount (100% by mass) of the styrene resin (A). preferably.

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

An example of a method for polymerizing a styrene-based copolymer resin that can be used in the present embodiment will be described below.
When the raw material for polymerization is polymerized to obtain the styrenic copolymer resin, the raw material composition for polymerization is typically made to contain a polymerization initiator and a chain transfer agent.
Polymerization initiators used for polymerization of styrene copolymer resins include organic peroxides such as 2,2-bis(t-butylperoxy)butane, 1,1-bis(t-butylperoxy)cyclohexane, n -Peroxyketals such as butyl-4,4-bis(t-butylperoxy)valerate, dialkyl peroxides such as di-t-butyl peroxide, t-butylcumyl peroxide, dicumyl peroxide, acetyl peroxide, isobutyryl Examples include diacyl peroxides such as peroxides, peroxydicarbonates such as diisopropylperoxydicarbonate, peroxyesters such as t-butylperoxyacetate, ketone peroxides such as acetylacetone peroxide, and hydroperoxides such as t-butyl hydroperoxide. be able to. Among them, 1,1-bis(t-butylperoxy)cyclohexane is preferred from the viewpoint of decomposition rate and polymerization rate.
Chain transfer agents used for polymerization of styrene copolymer resins include, for example, α-methylstyrene linear dimer, n-dodecylmercaptan, t-dodecylmercaptan, n-octylmercaptan and the like.

As a method for polymerizing the styrene-based copolymer resin, solution polymerization using a polymerization solvent can be employed as necessary. Examples of the polymerization solvent to be used include aromatic hydrocarbons such as ethylbenzene and dialkyl ketones such as methyl ethyl ketone, each of which may be used alone or in combination of two or more. Other polymerization solvents such as aliphatic hydrocarbons can be further mixed with the aromatic hydrocarbons as long as they do not reduce the solubility of the polymerization product. These polymerization solvents are preferably used in an amount not exceeding 25 parts by mass with respect to 100 parts by mass of the total monomers. If the amount of the polymerization solvent exceeds 25 parts by mass with respect to 100 parts by mass of the total monomers, the polymerization rate tends to decrease significantly and the mechanical strength of the resulting resin tends to decrease significantly. Addition of 5 to 20 parts by mass per 100 parts by mass of all monomers prior to polymerization facilitates homogenization of quality and is also preferable from the viewpoint of polymerization temperature control.

In the present embodiment, the apparatus used in the polymerization step for obtaining the 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 in which one or a plurality of complete mixing reactors are connected can be used. Also, the devolatilization step is not particularly limited. For example, when adopting bulk polymerization, the unreacted monomer is preferably 50% by mass or less, more preferably 40% by mass or less. Then, devolatilization treatment is performed by a known method. More specifically, for example, a flash drum, a twin-screw devolatilizer, a thin-film evaporator, an extruder, or other ordinary devolatilizer can be used, but a devolatilizer with a small stagnant portion is preferred. The temperature of the devolatilization treatment is usually about 190 to 280° C., and more preferably 190 to 260° C. from the viewpoint of suppressing the formation of a six-membered cyclic acid anhydride due to the adjacency of methacrylic acid and methyl methacrylate. . The pressure of the devolatilization treatment is usually about 0.13 to 4.0 kPa, preferably 0.13 to 3.0 kPa, more preferably 0.13 to 2.0 kPa. Desirable devolatilization methods include, for example, a method of reducing the pressure under heating to remove the volatile matter, and a method of removing the volatile matter through an extruder or the like designed for the purpose of removing the volatile matter.

<Cellulose-based polysaccharide (B) (hereinafter also referred to as component (B))>
The styrene-based resin composition or styrene-based resin composition sheet of the present embodiment contains a cellulose-based polysaccharide (B).
The content of the cellulose-based polysaccharide (B) in the present embodiment is 3 to 30% by mass with respect to the total amount (100% by mass) of the styrene-based resin composition or styrene-based resin composition sheet. By setting the content of the cellulose polysaccharide (B) to 3% by mass or more, heat mold retention and oil resistance can be improved. On the other hand, if the content is too high, the moldability is remarkably lowered due to the decrease in fluidity. The cellulose content in the styrenic resin composition sheet or the styrenic resin composition that is the precursor of the sheet is the solvent in which the styrenic resin (A) dissolves the styrenic resin composition sheet or the styrenic resin composition. , the undissolved material is taken out, dried at 120° C. for 4 hours, and then weighed.

In this embodiment, at least one of the average length of the short axis d ₁ or the long axis d ₂ of the cellulosic polysaccharide (B) is 0.03 to 80 μm, preferably 0.05 to 60 μm, It is preferably 0.1 to 50 μm, more preferably 0.2 to 30 μm. If the average length of the minor axis and the major axis is outside the above range, the heat mold retention may not be sufficiently exhibited, or the moldability may deteriorate. On the other hand, when the average length of the minor axis and the major axis is within the above range, the aggregation of cellulose can be reduced, the dispersibility in the styrene resin (A) is improved, and the oil resistance and moldability are improved.
In the present invention, the average length _d1 of the minor axis of the cellulose-based polysaccharide (B) is the minor-axis length of 100 pieces of the cellulose-based polysaccharide (B) by transmission electron microscope observation (magnified 5000 times). (Minimum length) is measured and the arithmetic mean is obtained. On the other hand, the average length of the long axis of cellulose is obtained by measuring the long axis length (maximum length) of 100 cellulose-based polysaccharides (B) by observation with a transmission electron microscope (5000x), and taking the arithmetic mean thereof. It is required by In addition, the minor axis length (minimum length) of the cellulose-based 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-based polysaccharide (B) length) refers to the length of the longest point on the image. Heat retention is affected by the shape of cellulose, and in the case of fibers, the short axis, scale-like or granular fiber is affected by the average diameter of the long axis.
The shape of the cellulose-based polysaccharide (B) in the present invention is not particularly limited, and examples thereof include spherical, irregular, powdery, scale-like, fibrous, and rod-like shapes.
The aspect ratio (d ₁ /d ₂ ) of the cellulosic polysaccharide (B) in the present invention is preferably 1 to 500, more preferably 1.2 to 300, and 1.5 to 200. is more preferred, and 2 to 100 is particularly preferred.

The cellulosic polysaccharide (B) in the present invention refers to polysaccharides having a β-1,4-glucan structure, including cellulose and hemicellulose. In addition, the material of the cellulosic polysaccharide (B) is not particularly limited as long as the fibers constituting the cellulosic polysaccharide (B) are formed of a polysaccharide having a β-1,4-glucan structure. , For example, cellulose fibers derived from higher plants [e.g., wood fibers (wood pulp of conifers, hardwoods, etc.), bamboo fibers, sugarcane fibers, seed hair fibers (cotton linter, bombax cotton, kapok, etc.), ginskin fibers ( For example, hemp, paper mulberry, mitsumata, etc.), natural cellulose fibers (pulp fibers) such as leaf fibers (e.g., Manila hemp, New Zealand hemp, etc.), animal-derived cellulose fibers (hoya cellulose, etc.), bacterial-derived cellulose fibers, chemical Organically synthesized cellulose fibers [organic acid esters such as cellulose acetate (cellulose acetate), cellulose propionate, cellulose butyrate, cellulose acetate propionate, cellulose acetate butyrate; cellulose nitrate, cellulose sulfate, cellulose phosphate, etc. mixed acid esters such as cellulose nitrate; hydroxyalkyl cellulose (e.g., hydroxyethyl cellulose (HEC), hydroxypropyl cellulose, etc.); carboxyalkyl cellulose (carboxymethyl cellulose (CMC), carboxyethyl cellulose, etc.); alkyl cellulose (methyl cellulose , ethyl cellulose, etc.); cellulose derivative fibers such as regenerated cellulose (rayon, cellophane, etc.), etc.] and the like. You may use these fibers which comprise a cellulose polysaccharide (B) individually or in combination of 2 or more types.

Among the fibers constituting the cellulose-based polysaccharide (B), the production efficiency is high in terms of dispersibility, rigidity, and impact resistance when the cellulose-based polysaccharide (B) is produced, and moderate fiber diameter and fiber length plant-derived cellulose fibers, for example, pulp-derived cellulose fibers such as wood fibers (softwood, hardwood, bamboo pulp, etc.) and seed hair fibers (cotton linter pulp, etc.).
In the present embodiment, the content of lignin is preferably 10% by mass or less, more preferably 5% by mass or less, relative to the cellulosic polysaccharide (B). If the lignin content is more than 10% by mass, odor and coloration increase during heat processing, and lignin-degraded products become black spots on the charcoal, lowering the product value and causing holes when heated in a microwave oven.
Furthermore, in the present embodiment, it is preferable that hemicellulose is contained in an amount of 1% by mass or more relative to the cellulosic polysaccharide (B). By containing hemicellulose, the dispersibility with the styrene resin (A) is improved, and the rigidity and molding appearance can be improved. In the present invention, it is preferable that these components are not completely removed in the cellulose manufacturing process, but are left in a suitable range of content. Hemicellulose is a polysaccharide composed of sugars such as mannan and xylan, and plays a role in binding microfibrils by forming hydrogen bonds with cellulose. In addition, since the solubility parameter (SP value) of hemicellulose is on the more hydrophobic side than cellulose, hemicellulose has the effect of alleviating the SP value difference between the styrene resin (A) and the cellulose polysaccharide (B). considered to have The amount of hemicellulose can be adjusted to a desired amount by subjecting natural wood raw materials with a high hemicellulose content to a refining treatment. A desired amount can be adjusted by adding hemicellulose obtained by extraction from another raw material. At this time, the structure of hemicellulose, such as terminal ends, may be partially different from the natural product due to purification or extraction treatment.

In the present embodiment, for the purpose of alleviating the SP value difference between the styrene resin (A) and the cellulose polysaccharide (B), hemicellulose is added to the cellulose polysaccharide (B) (100% by mass). More preferably 25% by mass or less, more preferably 2% by mass or more and 20% by mass or less, even more preferably 3% by mass or more and 20% by mass or less, 5% by mass or more and 19.5% by mass It is even more preferable that it is contained by mass or less, and it is particularly preferable that it is contained in an amount of 7% by mass or more and 19.3% by mass or less.

<Dispersant (C) (hereinafter also referred to as component (C))>
The styrene-based resin composition or styrene-based resin composition sheet of the present embodiment may contain a dispersant (C) if necessary. By including the dispersant (C) in the styrene-based resin composition or the composition sheet, the cellulose-based polysaccharide (B) can be uniformly dispersed in the styrene-based resin (A). As a result, the styrene-based resin composition sheet as a whole can be improved in heat mold retention and oil resistance without lowering the mechanical strength.
In the present embodiment, the content of the dispersant (C) is 0 to 10% by mass, preferably 0.1%, based on the total amount (100% by mass) of the styrene resin composition or the styrene resin composition sheet. 5 to 5% by mass, more preferably 1 to 3% by mass.
As the dispersant (C) in the present embodiment, fatty acid ester compounds, polyethylene glycol compounds, terpene compounds, rosin compounds, fatty acid amides, fatty acid compounds, or fatty acid metal salts can be used. In particular, 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.

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, palmitin. Isopropyl acid, octyl palmitate, coconut fatty acid octyl ester, octyl stearate, tallow fatty acid octyl ester, lauryl laurate, stearyl stearate, behenyl behenate, cetyl myristate, C28-30 linear unbranched Ester of saturated monocarboxylic acid (hereinafter abbreviated as montanic acid) and ethylene glycol, ester of montanic acid and glycerol, ester of montanic acid and butylene glycol, ester of montanic acid and trimethylolethane, ester 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 and the like. These may be used alone or in combination of two or more.

The polyethylene glycol-based 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 ester, polypropylene glycol glycerin esters, polyethylene sorbitol esters, polypropylene glycol sorbitol esters, polyethylene glycol ethylenediamines, polypropylene glycol ethylenediamines, polyethylene glycol diethylenetriamines and polypropylene-glycolized diethylenetriamines.

As the terpene-based resin, a terpene monomer alone, or a terpene monomer and an aromatic monomer, or a terpene monomer and a phenol are usually copolymerized in an organic solvent in the presence of a Friedel-Crafts-type catalyst. However, it is not limited to these. Examples of the terpene monomer include hemiterpenes having 5 carbon atoms such as isoprene, α-pinene, β-pinene, dipentene, d-limonene, myrcene, alloocimene, ocimene, α-phellandrene, α-terpinene, and γ-terpinene. , terpinolene, 1,8-cineole, 1,4-cineol, α-terpineol, β-terpineol, γ-terpineol, sabinene, paramentadienes, monoterpenes having 10 carbon atoms such as carenes, caryophyllene, longifolene, etc. sesquiterpenes having 15 carbon atoms, diterpenes having 20 carbon atoms, and the like, but are not limited thereto. Among these compounds, α-pinene, β-pinene, dipentene and d-limonene are particularly preferably used. Examples of the aromatic monomer include, but are not limited to, styrene, α-methylstyrene, vinyltoluene, isopropenyltoluene, and the like. The phenols include phenol, cresol, xylenol, bisphenol A and the like, but are not limited to these.
Moreover, the hydrogenated terpene-based resin obtained by hydrogenating the obtained terpene-based resin may be used. For example, preferred terpene-based resins include terpene-based resins such as α-pinene resin, β-pinene resin, aromatic modified terpene resin, terpene phenolic resin, and hydrogenated terpene resin. The terpene-based resins may be used alone or in combination of two or more.

Examples of the rosin-based resin include, in addition to rosins such as gum rosin, wood rosin, and tall oil rosin, stabilized rosins obtained by disproportionating or hydrogenating the above rosins, and polymerized rosins that are multimers of the above rosins (typically is a dimer), modified rosins modified with unsaturated acids such as maleic acid, fumaric acid and (meth)acrylic acid. Examples of rosin derivative resins include esterified products of the above rosin resins, phenol-modified products, esterified products thereof, and the like. The rosin-based resins may be used singly or in combination of two or more. The rosin-based resin or rosin derivative resin used in the present invention is not limited to these resins.
Examples of the aliphatic amide include stearic acid amide, oleic acid amide, erucic acid amide, behenic acid amide, ethylene bis stearic acid amide, ethylene bis oleic acid amide, ethylene bis erucic acid amide, and ethylene bis lauric acid amide. . These may be used alone or in combination of two or more.

Specific examples of saturated fatty acids among the above fatty acid compounds include lauric acid (dodecanoic acid), isodecanoic acid, tridecylic acid, myristic acid (tetradecanoic acid), pentadecylic acid, palmitic acid (hexadecanoic acid), margaric acid (heptadecane acid), stearic acid (octadecanoic acid), isostearic acid, tubercrostearic acid (nonadecanic acid), 2-hydroxystearic acid, arachidic acid (icosanoic acid), behenic acid (docosanoic acid), lignoceric acid (tetradocosanoic acid), serotin acid (hexadocosanoic acid), montanic acid (octadocosanoic acid), melissic acid and the like, particularly 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.

Among the above fatty acid compounds, unsaturated fatty acids include, specifically, 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), elestearin acid (9,11,13-octadecatrienoic acid), gadoleic acid (icosanoic acid), erucic acid (docosanoic acid), nervonic acid (tetradocosanoic acid) and the like. 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 fatty acids of the fatty acid compounds. These may be used alone or in combination of two or more.

<Compatibilizer (D) (hereinafter also referred to as component (D))>
The styrene-based resin composition or styrene-based resin composition sheet of the present embodiment may contain a compatibilizer (D) if necessary. The compatibilizer (D) of the present invention can be used without any particular limitation as long as it is a rubber-like polymer (a2). The compatibilizer (D) is desirably 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% by mass with respect to the total amount (100% by mass) of the styrene resin composition sheet or the styrene resin composition. , more preferably 1 to 5% by mass, more preferably 2 to 4% by mass.
In the styrene resin composition sheet or the styrene resin composition of the present invention, the rubber components contained in the styrene resin composition sheet or the styrene resin composition (rubber-like polymer (a1) and rubber-like polymer (a2) and the total amount) is preferably 3 to 20% by mass, based on the total amount (100% by mass) of the styrene resin composition sheet or the styrene resin composition, and 5 to 15% by mass. more preferably 6 to 11% by mass.

Examples of the rubber-like polymer (a2) of the present 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, hydrogenated styrene-isoprene-styrene block copolymer, ethylene-propylene copolymer, ethylene-1-butene copolymer, ethylene-α -Olefin copolymers, ethylene-propylene-ethylidene norbornene copolymers, ethylene-vinyl acetate copolymers, linear low-density polyethylene elastomers, acrylic elastomers, polyester/polyether co-elastomers, polyamide elastomers, etc. Among them, styrene-ethylene-butylene-styrene copolymer, styrene-ethylene-propylene copolymer, ethylene-propylene copolymer, ethylene-1-butene copolymer, ethylene-α-olefin copolymer, ethylene -propylene-ethylidene norbornene copolymers are preferred.

Unsaturated carboxylic acids, anhydrides, or derivatives thereof that modify the rubber-like polymer (a2) of the present 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, C 1-20 Among them, maleic acid and maleic anhydride are preferred. Examples of the method of modifying the rubber-like polymer component with an unsaturated carboxylic acid or the like include a method of graft-polymerizing an unsaturated carboxylic acid or the like to the rubber-like polymer (a2).

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, and maleic acid-modified ethylene-propylene. Copolymers, maleic acid-modified ethylene-1-butene copolymers, maleic acid-modified ethylene-α-olefin copolymers, maleic acid-modified ethylene-propylene-ethylidene norbornene copolymers, 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 copolymers, maleic anhydride-modified ethylene-propylene-ethylidenenorbornene copolymers, etc., and these can be used alone or in combination of two or more.

<Optional Addition Ingredients>
In addition to the above components (A) to (D), the styrenic resin composition of the present embodiment may optionally be added with known additives, processing aids, etc., as long as the effects of the present invention are not impaired. Ingredients can be added. Examples of these additives, processing aids, and the like include lubricants, antioxidants, weathering agents, antistatic agents, fillers, and the like.

The lubricant is as described above. Further, examples of the antioxidant include phenol compounds, phosphorus compounds, thioether compounds, and the like.
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-tertbutyl-4-hydroxyphenyl)propionamide], 4,4′-thiobis(6-tert-butyl-m -cresol), 2,2′-methylenebis(4-methyl-6-tert-butylphenol), 2,2′-methylenebis(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) methyl propionate] methane, thiodiethylene glycol bis [(3,5-di -tert-butyl-4-hydroxyphenyl)propionate], 1,6-hexamethylenebis[(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], bis[3,3-bis(4- hydroxy-3-tert-butylphenyl)butyric acid]glycol ester, bis[2-tert-butyl-4-methyl-6-(2-hydroxy-3-tert-butyl-5-methylbenzyl)phenyl]terephthalate, 1,3,5-tris[(3,5-di-tert-butyl-4-hydroxyphenyl)propionyloxyethyl]isocyanurate, 3,9-bis[1,1-dimethyl-2-{(3-tert -Butyl-4-hydroxy-5-methylphenyl)propionyloxy}ethyl]-2,4,8,10-tetraoxaspiro[5,5]undecane, triethylene glycol bis[(3-tert-butyl-4- hydroxy-5-methylphenyl)propionate] and the like. These may be used singly or in combination of two or more.

Examples of the phosphorus antioxidant include tris(2,4-di-tert-butylphenyl)phosphite, trisnonylphenylphosphite, tris[2-tert-butyl-4-(3-tert-butyl- 4-hydroxy-5-methylphenylthio)-5-methylphenyl]phosphite, tridecylphosphite, octyldiphenylphosphite, di(decyl)monophenylphosphite, di(tridecyl)pentaerythritol diphosphite, di( nonylphenyl)pentaerythritol diphosphite, bis(2,4-tert-butylphenyl)pentaerythritol diphosphite, bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphite, bis (2,4,6-tri-tert-butylphenyl) pentaerythritol diphosphite, bis(2,4-dicumylphenyl) pentaerythritol diphosphite, tetra(tridecyl)isopropylidene diphenol diphosphite, tetra( tridecyl)-4,4′-n-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)biphenylenediphosphonite, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 2,2 '-methylenebis(4,6-tert-butylphenyl)-2-ethylhexylphosphite, 2,2'-methylenebis(4,6-tert-butylphenyl)-octadecylphosphite, 2,2'-ethylidenebis(4 ,6-di-tert-butylphenyl)fluorophosphite, tris(2-[(2,4,8,10-tetrakis-tert-butyldibenzo[d,f][1,3,2]dioxaphosphite Pin-6-yl)oxy]ethyl)amine, phosphite of 2-ethyl-2-butylpropylene glycol and 2,4,6-tri-tert-butylphenol and the like. These may be used singly or in combination of two or more.

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

As the weather resistant agent, an ultraviolet absorber, a hindered amine light stabilizer, and the like can be used. Examples of the ultraviolet absorber include 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 5,5′-methylenebis(2-hydroxy-4-methoxybenzophenone ) and other 2-hydroxybenzophenones; 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'-tert -octylphenyl)benzotriazole, 2-(2'-hydroxy-3',5'-dicumylphenyl)benzotriazole, 2,2'-methylenebis(4-tert-octyl-6-(benzotriazolyl) ) phenol), 2-(2′-hydroxyphenyl)benzotriazoles such as 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, and other benzoates; 2-ethyl-2'-ethoxyoxaanilide, 2-ethoxy-4'-dodecyloxanilide, and other substituted oxanilides cyanoacrylates such as ethyl-α-cyano-β, β-diphenylacrylate, methyl-2-cyano-3-methyl-3-(p-methoxyphenyl)acrylate; 2-(2-hydroxy-4-octoxy phenyl)-4,6-bis(2,4-di-tert-butylphenyl)-s-triazine, 2-(2-hydroxy-4-methoxyphenyl)-4,6-diphenyl-s-triazine, 2- triaryltriazines such as (2-hydroxy-4-propoxy-5-methylphenyl)-4,6-bis(2,4-di-tert-butylphenyl)-s-triazine; These may be used singly or in combination of two or more.

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 -butane tetracarboxylate, tetrakis(1,2,2,6,6-pentamethyl-4-piperidyl)-1,2,3,4-butane tetracarboxylate, 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-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, Hindered amine compounds such as 11-tris[2,4-bis(N-butyl-N-(1,2,2,6,6-pentamethyl-4-piperidyl)amino)-s-triazin-6-yl]aminoundecane is mentioned. These may be used singly or in combination of two or more.

Cationic, anionic, nonionic, amphoteric, and fatty acid partial esters such as glycerin fatty acid monoester can be used as the antistatic agent.
Specifically, alkyltrimethylammonium salts, dialkyldimethylammonium salts, benzalkonium salts, N,N-bis(2-hydroxyethyl)-N-(3-dodecyloxy-2-hydroxypropyl)methylammonium mesosulphate , (3-laurylamidopropyl)trimethylammonium methylsulfate, stearamidopropyldimethyl-2-hydroxyethylammonium nitrate, stearamidopropyldimethyl-2-hydroxyethylammonium phosphate, cationic polymer, alkylsulfonate , Alkyl benzene sulfonate, Sodium alkyl diphenyl ether disulfonate, Alkyl nitrate ester salt, Phosphate alkyl ester salt, Alkyl phosphate amine salt, Stearate monoglyceride, Pentaerythritol fatty acid ester, Sorbitan monopalmitate, Sorbitan monostearate, Diglycerin fatty acid Esters, alkyldiethanolamines, alkyldiethanolamine fatty acid monoesters, alkyldiethanolamides, polyoxyethylene dodecyl ethers, polyoxyethylene alkylphenyl ethers, polyethylene glycol monolaurates, polyoxyethylene alkylamines, polyoxyethylene alkylamides, polyether block copolymers , cetyl betaine, hydroxyethylimidazoline sulfate, and the like. These may be used singly or in combination of two or more.

Talc, calcium carbonate, barium sulfate, carbon fiber, mica, wollastonite, whiskers, and the like can be used as the filler.
In addition, anti-blocking agents, coloring agents, anti-blooming agents, surface treatment agents, antibacterial agents, anti-stain agents (silicone oil described in JP-A-2009-120717, monoamide compounds of higher aliphatic carboxylic acids, and higher fatty acid An optional additive component such as an anti-mucus agent such as a monoester compound obtained by reacting a group carboxylic acid with a monohydric to trihydric alcohol compound may be added.

In this embodiment, the total content of the optional additive components may be 0.05 to 5% by mass in the styrenic resin composition.

The styrenic resin composition of the present embodiment includes substantially only the (A) component, the (B) component and the optional additive component, or substantially the (A) component, the (B) component, the (C) component and the optional additive component. Component only, or substantially only (A) component, (B) component, (D) component and optionally added component only, or substantially (A) component, (B) component, (C) component, (D) component and optional additive components. Another form of the styrenic resin composition of the present embodiment is substantially (A) component and (B) component, or substantially (A) component, (B) component and (C) component, or It may consist essentially of components (A), (B) and (D), or may consist essentially of components (A), (B), (C) and (D).
In the present specification, "consisting essentially of (A) component, (B) component and optional additive component" means 95 to 100% by mass with respect to the total amount (100% by mass) of the styrene resin composition. (preferably 98 to 100% by mass) are components (A) and (B), or components (A), (B) and optional additives.
The styrenic resin composition of the present embodiment may contain impurities in addition to components (A) to (D) and optional additive components within a range that does not impair the effects of the present invention.

[Method for producing styrene resin composition]
The styrenic resin composition of the present embodiment can be produced by melt-kneading each component by an arbitrary method. For example, a method using a high-speed stirrer typified by a Henschel mixer, a batch kneader typified by a Banbury mixer, a single-screw or twin-screw continuous kneader, a roll mixer, or the like may be used alone or in combination. The heating temperature during kneading is usually selected in the range of 180 to 250°C.
The above is the description of the styrene-based resin composition for producing the sheet of the present embodiment. The styrene-based resin composition sheet and the sheet of the present embodiment will be described below.

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

(extrusion sheet)
A preferred form of the styrene-based resin composition sheet of the present embodiment provides an extruded sheet formed using the above-described styrene-based resin composition of the present invention. The extruded sheet can be either non-foamed or foamed. As a method for producing the extruded sheet, a commonly known method can be used. As a method for producing a non-foamed extruded sheet, a method using a short-screw or twin-screw extruder equipped with a T-die and a device for taking out the sheet with a uniaxial stretching machine or a biaxial stretching machine can be used. As a method for producing the extruded sheet, a method using an extrusion foam molding machine equipped with a T-die or a circular die can be used.

- Foam extruded sheet -
In the present embodiment, when forming a foamed extruded sheet, substances commonly used as a foaming agent and foaming nucleating agent at the time of extrusion foaming can be used. As the foaming agent, butane, pentane, Freon, carbon dioxide, water, etc. can be used, and butane is preferred. Also, talc or the like can be used as a foam nucleating agent.

In the present embodiment, the foam 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. Preferably. The foam extruded sheet of the present invention may be multi-layered, for example, by further laminating films. The type of film used may be that used for general polystyrene.

-Non-foam extruded sheet-
In this embodiment, the thickness of the non-foamed sheet is preferably, for example, about 0.1 to 1.0 mm from the viewpoint of rigidity and thermoforming cycle. In addition, a uniaxial sheet may be formed only by normal roll stretching at a low magnification, and a biaxially stretched sheet may be formed by stretching about 1.3 to 7 times in the machine direction (MD) with a roll, and then vertically stretching with a tenter. Stretching in the direction (TD) by about 1.3 to 7 times is preferable in terms of strength. Also, the non-foamed sheet may be used in a multi-layered manner with a styrene-based resin such as a polystyrene resin other than the styrene-based resin composition. Further, it may be used in a multi-layered manner with a resin other than a styrene-based resin. Examples of resins other than the styrene-based resins include PET resins and nylon resins.

<Biaxially stretched sheet>
Another aspect of the styrene-based resin composition sheet of the present embodiment is a biaxially stretched sheet formed using the above-described styrene-based resin composition. As a method for producing a biaxially stretched sheet, a commonly known method can be used. The biaxially stretched sheet is produced by stretching in the machine direction (MD) with a roll and then stretching in the vertical direction (TD) with a tenter, or a styrene resin composition molded into a plate is stretched with the composition. It may be produced by sequentially or simultaneously biaxially stretching with a tenter in a state of being heated to about Vicat softening temperature +10 to 40°C.

As the draw ratio of the biaxially stretched sheet of the present embodiment, it is preferable to draw 1.3 to 7.0 times in the MD direction and 1.3 to 7.0 times in the TD direction from the viewpoint of strength.

The average thickness of the biaxially stretched sheet of the present embodiment is preferably 0.1 mm or more, more preferably 0.15 mm or more, and still more preferably 0.2 mm or more, in order to ensure the strength, particularly rigidity, of the sheet and container. be. On the other hand, from the viewpoint of economy, it is preferably 0.7 mm or less, more preferably 0.6 mm or less, and even more preferably 0.5 mm or less.

The biaxially stretched sheet of the present embodiment preferably has a longitudinal and transverse orientation relaxation stress in the range of 0.4 to 1.3 MPa. By adjusting the orientation relaxation stress within this range, the strength of the biaxially oriented sheet molded product can be maintained.

When the biaxially oriented sheet of the present embodiment is used as a food packaging container, a known antifogging agent may be applied to at least one side of the biaxially oriented sheet in order to prevent fogging due to moisture volatilized from the food. Examples of the antifogging agent include nonionic surfactants such as sucrose fatty acid esters and polyglycerin fatty acid esters, and polyether-modified silicone oils.
The method of applying the above antifogging agent to the biaxially oriented sheet of the present embodiment is not particularly limited, and a convenient method includes a method of applying using a roll coater, a knife coater, a gravure roll coater, or the like. Alternatively, spraying, immersion, or the like can be employed. In addition, before coating, the wettability of the surface of the biaxially oriented sheet may be improved by subjecting the surface to corona treatment, ozone treatment, primer treatment, or the like before coating.

[Secondary molded product]
Another aspect of this embodiment provides molded articles, particularly food containers, formed using the extruded sheet described above. A biaxially stretched sheet or a multi-layered body containing the same can be formed into, for example, a food container, such as a lid material for a boxed lunch or a container for containing a side dish by vacuum forming.
<Food container>
The food container of the present invention is formed from the above styrene resin composition or styrene resin composition sheet. A preferred form of the food container of the present invention will be described below with reference to FIGS. 1 and 2. FIG.

FIG. 1 shows an example of a food container 1 according to the present invention, and the member on the lower side of FIG. 1 is a perspective view showing a food container main body 2 for mainly containing food such as noodles or rice bowls. , the member on the upper side of FIG. In FIG. 1, for convenience of explanation, as an example of the food container 1 of the present embodiment, the food container body 2 and the lid portion 3 that can be fitted into the opening 6 of the food container body 2 are shown. The food container 1 in the form may have only the food container main body 2 .
Moreover, FIG. 2 is a schematic diagram showing a cross section of a mold 9 for manufacturing the food container 1 (particularly, the food container main body 2) of FIG.

The shape of the food container 1 of this embodiment and the method of forming the same will be described below with reference to FIG.
The food container body 2 of this embodiment has a recess 4 that can accommodate food. FIG. 1 shows a food container 1 having one recess 4 as an example of the recess 4. A groove 5 is formed in the inner wall of the food container body 2 along the entire circumference so that the amount of the contents can be visually recognized from the outside. there is The area of the bottom surface of the food container body 2 is smaller than the area of the opening 6 . Further, the opening 6 of the food container body 2 is provided with a rim 7 projecting outward, and the lid 3 covering the opening 6 of the food container body 2 and the rim 7 are fitted. sell.
The shape of the recess 4 is not particularly limited, and examples thereof include a (substantially) cylindrical shape, a polygonal cylindrical shape, and the like.
Moreover, the food container in this embodiment may have a plurality of recesses 4 . A form of the food container having a plurality of recesses 4 includes a shape in which a plurality of side dishes, which are foods, are partitioned by a partition wall, like a food container used for commercially available lunch boxes.

The food container 1 in this embodiment can be manufactured using, for example, the mold 9 shown in FIG. As an example of the present embodiment, referring to FIG. 2, the aspect in which the food container 1 (food container body 2) is integrally molded from a styrene resin composition sheet 10 formed by molding a styrene resin composition will be described below. explain.
For example, a styrene resin composition sheet 10 having a thickness of 100 to 1000 μm is produced by extrusion molding a styrene resin composition. At that time, the surface layer of the styrene-based resin composition sheet 10 may be co-pressed with polystyrene or polypropylene or film-laminated to a thickness of 1 to 100 μm. After that, the obtained styrene resin composition sheet 10 is preheated at 150 to 250° C. for 5 to 60 seconds, and then the heated styrene resin composition sheet 10 is placed so as to cover the concave portion 11 of the mold 9. , shaped by a predetermined molding method. For example, by evacuating the concave portion 11, the desired shape of the food container body 2 can be formed.
Also, after the styrene resin composition sheet 10 is placed so as to cover the recess 11 of the mold 9, it is heated and shaped by a predetermined molding method (for example, thermocompression molding, vacuum molding, air pressure molding, plug assist molding). may be shaped.

As an example of a preferred aspect of the present embodiment, the food container 1 (particularly, the food container main body 2) is made by using the mold 9 to form a heated styrene-based resin composition sheet 10 by thermocompression molding, vacuum molding, It can be shaped by pressure forming or plug assist forming.
When manufacturing food containers 1 (especially food container bodies 2) with different depths, the ratio (d /r) can be varied. FIG. 2 shows, as an example, a state in which the spacer 12 is provided in the recess 11 having the depth d so as to have the depth d2 or the depth d1.

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, more preferably 0.15 to 1.5 mm. If the thickness is less than 0.05 mm, the rigidity of the container will be insufficient, and if the thickness is more than 3 mm, the container will be heavy and the material cost will be high.
In this embodiment, the depth/opening diameter ratio (drawing ratio) of the food container is preferably 0.1 or more and 1.0 or less. If the drawing ratio is greater than 1.0, uneven thickness occurs and the strength of the container decreases. In addition, when the depth/diameter ratio is less than 0.1, the shape of the container becomes flat, so uneven thickness is less likely to occur, and the bottom surface of the food container (especially the outer peripheral portion of the bottom surface) is oily. Or, it is difficult to exhibit the effect of oil resistance due to the residual liquid containing oil. On the other hand, if the drawing ratio (ratio of depth/diameter) is 0.1 or more and 1.0 or less, not only is it relatively easy to accommodate the contents such as foods, but it also depends on the menu of foods that can be accommodated. It becomes easy to exhibit the effect of oil resistance without doing.
In this specification, the opening diameter means the diameter when the shape of the opening is circular, the shortest diameter when the shape of the opening is elliptical, and the shortest diagonal when the shape of the opening is polygonal. represents length.
Moreover, in order to keep the container airtight, it is preferable to design the upper part of the container to have an uneven shape to improve fitting. Since the food container used in the present invention has good shape retention by heat, it is a food container with excellent fitability.

The method for molding the food container according to the present invention includes injection molding, injection compression molding, extrusion molding, blow molding, press molding, thermocompression molding, vacuum molding, pneumatic molding, plug-assist molding and foam molding. etc. are used, and the molding method is not limited. For the food container used in the present invention, a method of shaping by vacuum forming after sheet (film) forming is preferred, particularly in terms of productivity and cost.
The food container according to the present invention is preferably molded from a styrene-based resin composition sheet, and more preferably shaped after molding the styrene-based resin composition sheet made of the styrene-based resin composition.

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 the thickness is less than 0.1 mm, the rigidity of the container will be insufficient.

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 styrenic resin sheet contains 70 to 97% by mass of styrene resin (A) and 3 to 30% by mass of cellulosic 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 so that the performance of the food container can be maintained.
In this embodiment, the styrene resin described later can be used as the styrene resin used for the material forming the food container. Moreover, polyethylene, polypropylene, polyvinyl acetate, polyvinyl alcohol, etc. are used as polyolefin, and they may be copolymers. Polypropylene is particularly preferred from the viewpoint of oil resistance. Methods for laminating the surface layer on the first layer include methods such as co-extrusion using an extruder and film lamination. The styrene-based resin sheet used in the present invention is characterized by excellent adhesiveness to polyolefin and less peeling due to heating or the like.

[Characteristics of food containers]
<Thermal mold retention>
It is preferable that the food container of this embodiment does not deform after being left in an oven at 100 to 130° C. for 30 minutes.

<Oil resistance>
As for the oil resistance of the food container of the present embodiment, it is desirable that the container filled with oil such as salad oil is not deformed when heated in a microwave oven.

The sheet of the present embodiment is excellent in vacuum formability and is suitably used for side dishes, lunch boxes, microwave oven containers, rice bowls, cups, trays, and the like.

EXAMPLES The embodiments of the present invention will be described in more detail below based on Examples and Comparative Examples, but the present invention is not limited to these Examples.

<Measurement and evaluation method>
The styrenic resin composition sheets and food containers obtained in Examples and Comparative Examples were evaluated according to the following methods.

(1) Evaluation of water contact angle After producing a styrene resin composition sheet by the method described in Examples and Comparative Examples below, a contact angle meter (DropMaster 500 manufactured by Kyowa Interface Science Co., Ltd.) was used to measure the water contact angle on the sheet surface. Three values were measured one minute after 2 μL of water droplets were dropped, and the average value was used.

(2) Evaluation of Appearance of Sheet The appearance of the sheet produced by the method described in Examples and Comparative Examples below was visually confirmed according to the following criteria.
Appearance evaluation criteria;
◯: No coloring, no lumps, △: Coloring, no lumps, ×: Coloring, lumps.
(3) Evaluation of odor of sheet After preparing a test piece by cutting the sheet prepared by the method described in Examples and Comparative Examples below into 100 mm × 100 mm × 0.5 mm (thickness), put it in a plastic bag with a zipper. After the test piece was put in and sealed, the plastic bag in which the test piece was sealed was allowed to stand at 23° C. for 24 hours, and the odor was sensory evaluated by two persons according to the following criteria.
Odor evaluation criteria;
◯: almost no odor, Δ: slight odor, ×: odor.

(4) Evaluation of heat mold retention A food container manufactured by the method described in Examples and Comparative Examples below was left in an oven at 120°C for 30 minutes, and the state of the food container was confirmed according to the following criteria.
◯: No change, Δ: Deformation on the bottom of the container, ×: Deformation on the entire container.

(5) Evaluation of oil resistance A food container filled with 5 ml of salad oil (salad oil manufactured by Nisshin Oillio Co., Ltd.) prepared by the method described in Examples and Comparative Examples below was heated in a 500 W microwave oven. After heating for 2 minutes, the condition of the food container was checked according to the following criteria.
◯: No change, Δ: Visible turbidity in salad oil, ×: Perforated.

(6) Evaluation of heat insulation A food container filled with 50 ml of boiling water in a food container prepared by the method described in Examples and Comparative Examples below is left at 23 ° C. for 30 minutes, and then the food container is heated. I measured the temperature of the water inside.

(7) Measurement of the content of styrene monomer units, methacrylic acid monomer units, and methyl methacrylate monomer units in the styrene resin (A) with a proton nuclear magnetic resonance ( ¹ H-NMR) spectrometer The resin composition was quantified from the integral ratio of the measured spectrum.
・Sample preparation: 30 mg of resin pellets were dissolved in 0.75 mL of d ₆ -DMSO by heating at 60° C. for 4 to 6 hours.
・Measurement equipment: JNM ECA-500 manufactured by JEOL Ltd.
Measurement conditions: measurement temperature of 25° C., observation core ^{of 1} H, accumulation times of 64, repetition time of 11 seconds.

(Assignment of spectra)
Regarding the assignment of spectra measured in dimethylsulfoxide heavy solvent, the peaks at 0.5 to 1.5 ppm are the peaks derived from the hydrogen of the α-methyl groups of methacrylic acid, methyl methacrylate, and six-membered cyclic acid anhydrides, The peak at 1.6 to 2.1 ppm is the peak derived from the hydrogen of the methylene group in the main chain of the polymer, the peak at 3.5 ppm is the peak derived from the hydrogen of the carboxylic acid ester (—COOCH ₃ ) of methyl methacrylate, and the peak at 12.4 ppm is The peak is derived from the hydrogen of the carboxylic acid of methacrylic acid. Also, the peak at 6.5 to 7.5 ppm is the peak derived from the hydrogen of the aromatic ring of styrene. In addition, since the resins of the present examples and comparative examples have a small content of six-membered cyclic acid anhydride, quantification is usually difficult by this measuring method.

(8) Measurement of Melt Flow Rate (MFR) The melt mass flow rate (g/10 minutes) of the styrene resin (A) was measured according to ISO 1133 (200°C, load 49N).

(9) Measurement of average length of cellulose-based polysaccharide (B) An ultra-thin section with a thickness of 75 nm was prepared from the test piece (b) prepared by the method described in Examples and Comparative Examples below, and an electron microscope was used. A photograph was taken at a magnification of 50,000 times. Then, the photograph is captured in a scanner at a resolution of 200 dpi, and the minimum length and maximum length of 100 cellulose-based polysaccharides (B) are determined using particle analysis software of an image analyzer IP-1000 (manufactured by Asahi Kasei Corporation). Each was measured, and the arithmetic mean of each was defined as the average short axis length d ₁ and the average length d ₂ of the long axis. In the same manner as described above, the cellulose-based polysaccharide (B) alone was also photographed using an electron microscope at a magnification of 50,000 times, and the arithmetic mean of each was calculated as the average short axis length d ₁ and the average length of the long axis. Measure the depth _d2 .

(10) Quantification of Lignin Amount Quantitative analysis of lignin in the cellulosic polysaccharide (B) was based on the TGA method described in Journal of the Japan Society of Waste Recycling, Vol.22, N0.5, P293, 2011.
Specifically, a DTG-60 model manufactured by Shimadzu Corporation was used as a thermogravimetric analyzer, and the temperature was raised from room temperature to 900° C. at a temperature elevation rate of 10° C./min in an air atmosphere. The sample to be analyzed was dried at 70° C. for 2 hours, weighed accurately in an amount of 3 to 5 mg, and the weight change due to thermal decomposition was measured. A disk-shaped platinum plate with an inner diameter of 5 mm and a height of 2 mm was used as a sample container, and all experiments were carried out under constant conditions.

(11) Measurement of amount of hemicellulose Quantitative analysis of hemicellulose in the cellulosic polysaccharide (B) is as follows.
The dispersion medium is removed from the dispersion of the cellulose polysaccharide (B) or the redispersion of the cellulose polysaccharide (B) obtained by dissolving and removing the resin from the styrene resin composition, and the cellulose residue is recovered. Then, the mass of the dried sample obtained by drying at 105°C was measured by the following method.
A pulverized sample obtained by pulverizing dried cellulose residue was extracted with alcohol (ethanol)/benzene mixed solvent) for 6 hours using a Soxhlet extractor. After that, extraction with alcohol (ethanol)/benzene mixed solvent) was performed for an additional 4 hours to obtain a defatted sample. 150 mL of distilled water, 1.0 g of sodium chlorite, and 0.2 mL of acetic acid are added to 2.5 g of the defatted sample, and heat treatment is performed at 70 to 80 ° C. for 1 hour. The operation of adding .2 mL and heating at 70 to 80° C. for 1 hour was repeated 3 to 4 times until the sample became white and decolored. The resulting sample was filtered, washed with water and acetone, and dried at 105° C. to obtain a holocellulose fraction (total amount of α-cellulose and hemicellulose). The mass of this holocellulose fraction was measured.
Subsequently, 25 mL of a 17.5% by mass sodium hydroxide aqueous solution was added to 1.0 g of the holocellulose fraction, and after 3 minutes, the mixture was lightly crushed with a glass rod until it became swollen. After that, leave the mixture at 20°C, and 30 minutes after adding the aqueous sodium hydroxide solution, add 25 mL of distilled water, stir for exactly 1 minute, leave at 20°C for 5 minutes, and filter through a glass filter. Wash until the liquid becomes neutral. Further, 40 mL of 10% by mass acetic acid was suction-filtered, then 1 L of boiling water was suction-filtered, and the washed sample was dried at 105° C. until the mass became constant to obtain an α-cellulose fraction. The mass of this α-cellulose fraction was measured.
From the masses of the holocellulose fraction and the α-cellulose fraction determined as described above, the hemicellulose content was determined by the following equation.
Holocellulose (%) = holocellulose fraction (g) / sample (anhydrous basis) (g) x 100
α-cellulose (%) = α-cellulose fraction (g) / sample (anhydrous basis) (g) × 100
Hemicellulose (%) = Holocellulose (%) - (α-cellulose (%))

Materials used in Examples and Comparative Examples are as follows.
[Styrene resin (A)]
(GPPS-1)
- Polystyrene (GPPS, PS Japan Co., Ltd., HF77) with an MFR of 7.8 was used.
(HIPS-1)
- MFR 3.0 polystyrene (HIPS, manufactured by PS Japan, HT478) was used.
(HIPS-2)
- MFR 2.0 polystyrene (HIPS, PS Japan Co., Ltd., 475D) was used.
(Copolymerization-1)
Polymerization 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 The raw material composition solution is transferred at a rate of 1.1 liters/hour to a fully mixed reactor having a capacity of 4 liters, then to a polymerization apparatus consisting of a laminar flow reactor having a capacity of 2 liters, and then to unreacted monomers. , to a devolatilization device connected to a single-screw extruder for removing volatile matter such as a polymerization solvent, to prepare Copolymer-1, which is a styrene-based copolymer resin.
The polymerization reaction conditions in the polymerization process were a polymerization temperature of 122° C. in the complete mixing reactor and a polymerization temperature of 120 to 142° C. in 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 liquid was measured by the formula [(sample mass after drying / sample mass before drying) x 100%] after drying the polymerization liquid for 30 minutes at 215 ° C. under a reduced pressure of 2.5 kPa. , 65.6 mass %, and the MFR was 4.6.
(Blend-1)
- The above HIPS-2 (475D) was blended with 5% by mass of an SMA copolymer (XIBOND250 manufactured by POLYSCOPE), and the MFR was 3.2.

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

[Dispersant (C)]
・ Fatty acid ester: glycerin monostearate (Riken Vitamin Co., Ltd.: S-100)
・ Terpene: aromatic modified terpene resin (manufactured by Yasuhara Chemical Co., Ltd.: YS resin TO-105)

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

[Additive]
(Phenolic antioxidant)
· 3-(3,5-di-tert-butyl-4-hydroxyphenyl) stearyl propionate (manufactured by BASF, Irganox 1076)
(Phosphorus antioxidant)
・ Tris (2,4-di-tert-butylphenyl) phosphite (manufactured by BASF, Irgafos168)

[Examples 1 to 12]
Each component was added in the composition ratio shown in Table 1, and the styrene-based resin (A) and the cellulose-based polysaccharide (B) were blended to prepare a styrene-based resin composition as a sheet precursor. At that time, after adding 0.2 parts by mass of each of Irganox 1076 and Irgafos 168 as antioxidants to 100 parts by mass of components (A) and (B), and if necessary in some examples , and 10 parts by mass of the dispersant (C) were added and premixed. The resulting preliminary mixture is mixed together and melt-extruded at a temperature of 180° C. to 220° C. using a twin-screw extruder (TEM-26SS, manufactured by Toshiba Machine Co., Ltd.) to obtain a resin of a styrene resin composition as a kneaded product. A pellet was obtained. At this time, the screw rotation speed was 150 rpm, and the discharge rate was 10 kg/hr.
A non-foamed extruded sheet was produced using the obtained resin pellets. As for the non-foamed extruded sheet, a 25 mmφ single-screw sheet extruder manufactured by Soken Co., Ltd. was used to set the temperature of the resin melting zone to 180 to 200° C., and a styrene-based resin composition sheet having a thickness of about 0.5 mm was produced. In addition, for Example 10, GPPS (680 manufactured by PS Japan Co., Ltd.) on both sides, and for Example 11, PP (E-100GV manufactured by Prime Polymer Co., Ltd.) was coextruded and laminated to a thickness of about 0.1 mm. I created a customized sheet.
Using the obtained styrene-based resin composition sheet, a food container having the shape shown in FIG. 1 was produced. For the food container, a sheet container molding machine manufactured by Soken Co., Ltd. was used to set the heating zone to 200° C., and a container with a drawing ratio of 75% represented by the following formula (1) was produced and subjected to vacuum forming. These evaluation results are shown in Table 1.
Equation (1) representing the drawing ratio is as follows.
Drawing ratio = depth of food container / opening diameter (maximum diameter) of food container x 100 Formula (1)
In addition, resin pellets were molded using an injection molding machine manufactured by Japan Steel Works, Ltd. equipped with an ISO standard test piece type of 50 × 120 mm and a thickness of 1 mm (b) mold, a cylinder temperature of 220 ° C., a mold temperature of 50 ° C., A test piece (b) was produced by molding under injection pressure (gauge pressure 40-60 MPa), injection speed (panel set value) 50%, and injection time/cooling time = 5 sec/20 sec. Using the obtained test piece (b), the average length of the cellulose-based polysaccharide (B) was measured.

[Comparative Examples 1 to 9]
Compositions of sheet precursors 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. Table 2 shows the results of measurement and evaluation of each physical property.

As shown in Table 1, Examples 1 to 12 are excellent in heat resistance, oil resistance, heat insulation and moldability.
As shown in Comparative Examples 1 to 9 shown in Table 2, the heat resistance and oil resistance are poor due to deformation at high temperatures and holes in microwave ovens. If there are many cellulose fibers as in Comparative Example 5, a product cannot be produced by vacuum forming. When wood powder is used as in Comparative Example 7, the coloring and odor are severe, and the oil resistance is also perforated.

An object of the present invention is to provide a styrenic resin composition sheet which reduces the environmental load, has excellent oil resistance and heat insulating properties, and has little odor and coloration. Molded articles obtained from the styrene resin composition sheet of the present invention can be suitably used for food containers such as trays, cups, rice bowls and lids.

Claims (6)

Styrene resin (A) 70.0 to 97.0% by mass,
3 to 30% by mass of a cellulose-based polysaccharide (B) having a lignin content of 10% by mass or less,
A styrene-based resin composition sheet whose surface has a contact angle with water in the range of 50° to 105°. The styrene-based resin composition sheet according to claim 1, wherein the hemicellulose content in the cellulose-based polysaccharide (B) is 1% by mass or more. 3. The styrene resin composition sheet according to claim 1, further comprising 0.5 to 10.0 parts by mass of a dispersant (C) with respect to 100 parts by mass of the total amount of the styrene resin composition sheet. 4. The dispersing agent (C) according to claim 3, which is one or more compounds selected from the group consisting of fatty acid ester compounds, polyethylene glycol compounds, terpene compounds, and rosin compounds. Styrene-based resin composition sheet. The styrene resin composition sheet according to any one of claims 1 to 4, further comprising 0.5 to 10.0 parts by mass of a compatibilizer (D) with respect to 100 parts by mass of the total amount of the styrene resin composition sheet. . 6. The styrenic resin composition sheet according to claim 5, wherein the compatibilizer (D) is a maleic anhydride-modified styrenic rubbery polymer.

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