Styrene resin composition and molded product thereof, film, sheet and foam

Abstract

To provide a resin composition that delivers superior hue and heat resistance, and reduces environmental load due to the incorporation of bean curd lees as biomass material, and a molded product, a film, a sheet and a foam, each obtained from the resin composition.SOLUTION: A resin composition comprises a styrene resin (A) and bean curd lees (B). When the total of the styrene resin (A) and the bean curd lees (B) is 100 pts.mass, the styrene resin (A) is 25 to 97 pts.mass and the bean curd lees (B) is 3 to 75 pts.mass. The bean curd lees (B) has a methanol soluble content of 7 to 25 mass%.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a resin composition which is compounded with soybean pulp and has excellent color and heat resistance, and to a molded article, a film and a foam obtained from the resin composition. [Background technology]

[0002] In the general production of soy milk and tofu, the residue left after soy milk is extracted from the soy beans is generated in an amount about 1.5 times that of the raw beans. In recent years, there has been a demand to reduce carbon dioxide emissions due to the problem of global warming, and biomass-derived materials have been attracting attention as "carbon-neutral" materials that do not emit carbon dioxide. However, although some of the resulting "okara" is used as food, most of it is treated as industrial waste and its use as biomass has not progressed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2012-017426 [Patent Document 2] Patent Publication No. 2007-076160 [Patent Document 3] Patent Publication No. 2003-335886 [Patent Document 4] Patent Publication No. 2000-167857 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to provide a resin composition which is excellent in hue and heat resistance and which has a low environmental impact by containing soybean pulp as a biomass raw material, and a molded article, film, sheet, and foam obtained from the resin composition. [Means for solving the problem]

[0005] (1) A resin composition comprising a styrene-based resin (A) and soybean pulp (B), characterized in that, when the total amount of the styrene-based resin (A) and the soybean pulp (B) is 100 parts by mass, the styrene-based resin composition contains 25 to 97 parts by mass of the styrene-based resin (A) and 3 to 75 parts by mass of the soybean pulp (B), and the soybean pulp (B) has a methanol-soluble content of 7 to 25% by mass. (2) The styrene-based resin composition according to (1), wherein the styrene-based resin (A) is a rubber-containing styrene-based resin. (3) The styrene-based resin composition according to (1) or (2), wherein the styrene-based resin (A) has a melt mass flow rate measured at 200° C. and 49 N of 3 g / 10 min or more. (4) A molded article made of the styrene-based resin composition according to any one of (1) to (3). (5) A film made of the styrene-based resin composition according to any one of (1) to (3). (6) A sheet made of the styrene-based resin composition according to any one of (1) to (3). (7) A foamed product made of the styrene-based resin composition according to any one of (1) to (3). Effect of the Invention

[0006] The resin composition of the present invention and the molded articles, films, sheets and foams made therefrom have a low environmental impact and are excellent in processability, color, heat resistance and rigidity, and can therefore be advantageously used in applications such as food containers and packaging, office automation equipment, home appliance parts and miscellaneous goods. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] Hereinafter, embodiments of the present invention will be described. The features of the embodiments described below can be combined with each other. Also, each feature can be an invention independently.

[0008] 1. Styrene-based resin composition A styrene-based resin composition according to one embodiment of the present invention contains a styrene-based resin (A) and soybean pulp (B). When the total of the styrene resin (A) and the soybean pulp (B) is 100 parts by mass, the content of the styrene resin (A) is 25 to 97 parts by mass, and preferably 70 to 90 parts by mass. Specifically, for example, it may be within the range of any two values ​​among 25, 30, 35, 40, 45, 50, 55, 60, 70, 80, 90, 95 and 97 parts by mass. Note that the styrene resin (A) may be used in combination with various styrene resins (A), and when various styrene resins (A) are used in combination, the amount of the styrene resin (A) used means the total amount of the styrene resins (A) used in combination.

[0009] When the total of the styrene-based resin (A) and the okara (B) is 100 parts by mass, the content of the okara (B) is 3 to 75 parts by mass, and preferably 10 to 30 parts by mass. Specifically, for example, it may be within the range of any two values ​​among 3, 5, 10, 20, 30, 40, 45, 50, 60, 70, and 75 parts by mass. Note that the okara (B) may be used in combination with various okara (B), and when various okara (B) are used in combination, the amount of the okara (B) used means the total amount of the okara (B) used in combination.

[0010] The methanol soluble content in the soybean pulp (B) is 7 to 25% by mass, and preferably 11 to 19% by mass. If the methanol soluble content is less than 7% by mass, the extrusion stability and pellet color of the styrene resin composition are reduced, and if the methanol soluble content exceeds 25% by mass, the Vicat softening point of the styrene resin composition is reduced. The methanol soluble content may be within any two of the ranges of 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, and 25% by mass.

[0011] <Styrene-based resin (A)> The styrene resin (A) is obtained by radical polymerization of an aromatic vinyl compound monomer (a1), and may be a rubber-containing styrene resin modified with a rubber polymer such as a conjugated diene rubber-like polymer, if necessary. The polymerization method may be a known method, such as bulk polymerization, two-stage bulk / suspension polymerization, or solution polymerization. The aromatic vinyl compound monomer is a monocyclic or polycyclic aromatic vinyl monomer, such as styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, 2,4-dimethylstyrene, 2,5-dimethylstyrene, 3,4-dimethylstyrene, 3,5-dimethylstyrene, p-ethylstyrene, m-ethylstyrene, o-ethylstyrene, p-tert-butylstyrene, 1-vinylnaphthalene, 2-vinylnaphthalene, 1,1-diphenylethylene, isopropenylbenzene (α-methylstyrene), isopropenyltoluene, isopropenylethylbenzene ... The styrene-based resin composition may contain a monomer such as styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, 2,4-dimethylstyrene, 2,5-dimethylstyrene, 3,4-dimethylstyrene, 3,5-dimethylstyrene, p-ethylstyrene, m-ethylstyrene, o-ethylstyrene, and p-tert-butylstyrene, or a mixture of two or more of these monomers. The styrene-based resin composition may contain a monomer such as acrylonitrile, (meth)acrylic acid, or (meth)acrylic acid ester, which is copolymerizable with these aromatic vinyl compound monomers, within a range that does not impair the performance of the styrene-based resin composition. Furthermore, in the present invention, a crosslinking agent such as divinylbenzene may be added to the styrene-based monomer and polymerized.

[0012] Conjugated diene rubbery polymers used for rubber modification of the styrene resin (A) of the present invention include polybutadiene, random or block copolymers of styrene-butadiene, polyisoprene, polychloroprene, random, block or graft copolymers of styrene-isoprene, ethylene-propylene rubber, ethylene-propylene-diene rubber, etc., and particularly preferred are polybutadiene, random, block or graft copolymers of styrene-butadiene. These may be partially hydrogenated and may be used alone or in combination of two or more kinds.

[0013] The content of the rubber-like polymer in 100 parts by mass of the styrene-based resin (A) according to this embodiment is preferably 1.0 to 25.0 parts by mass, more preferably 5.0 to 20.0 parts by mass, from the viewpoint of strength and rigidity. The content of the rubber-like polymer in this range is preferable because it provides a good balance between impact strength and rigidity. The content of the rubber-like polymer may be within any two of the following values: 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0, 11.0, 12.0, 13.0, 14.0, 15.0, 16.0, 17.0, 18.0, 19.0, 20.0, 21.0, 22.0, 23.0, 24.0, and 25.0 parts by mass. When a rubber-like polymer is used in combination, the amount of the rubber-like polymer used means the total amount of the rubber-like polymer used in combination.

[0014] The content of the rubber-like polymer can be measured, for example, as follows. The sample is dissolved in chloroform, a certain amount of iodine monochloride / carbon tetrachloride solution is added, and the mixture is left in a dark place for approximately 1 hour. After that, a 15% by mass potassium iodide solution and 50 ml of pure water are added, and the excess iodine monochloride is titrated with a 0.1 N sodium thiosulfate / ethanol aqueous solution, and the amount of iodine monochloride added is calculated.

[0015] The volume average particle diameter of the rubber-like polymer in the styrene-based resin (A) is preferably 2.0 to 8.0 μm from the viewpoint of strength and rigidity, and particularly preferably 2.3 to 7.0 μm. The volume median particle diameter in this range is preferable because it provides a good balance between impact strength and rigidity. The volume average particle diameter may be within any two values ​​of 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.2, 3.4, 3.6, 3.8, 4.0, 4.2, 4.4, 4.6, 4.8, 5.0, 5.5, 6.0, 6.5, 7.0, 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9, and 8.0. When a rubbery polymer is used in combination, the volume average particle size of the rubbery polymer means the volume average particle size of all the rubbery polymers used in combination.

[0016] The volume average particle size of the rubber-like polymer can be measured, for example, as follows. The sample is dissolved in dimethylformamide and measured using a laser diffraction particle size distribution device (Beckman Coulter Laser Diffraction Particle Analyzer "LS-230").

[0017] From the viewpoint of fluidity and heat resistance, the molecular weight of the styrene resin (A) is preferably 10,000 to 500,000 in terms of mass average molecular weight (Mw), more preferably 30,000 to 400,000. Specifically, for example, it may be 1, 2, 3, 4, 5, 10, 15, 20, 25, 30, 35, 40, 45, or 500,000, and may be within a range between any two of the numerical values ​​exemplified here. By setting it in such a range, a styrene resin composition having an excellent balance between fluidity and heat resistance can be obtained. The mass average molecular weight of the styrene resin (A) can be controlled by the reaction temperature and residence time of the polymerization step, the type and amount of polymerization initiator, the type and amount of chain transfer agent, the type and amount of solvent used during polymerization, and the like.

[0018] The Z-average molecular weight (Mz) of the styrene resin (A) of this embodiment is 200,000 or more, preferably 260,000 or more. Having Mz in this range is preferable because it provides excellent impact strength. The Mz of the styrene resin (A) can be adjusted by the reaction temperature and residence time in the polymerization step, the type and amount of the polymerization initiator, and the type and amount of the solvent used during polymerization.

[0019] The weight average molecular weight (Mw) and the Z average molecular weight (Mz) can be measured by gel permeation chromatography (GPC) under the following conditions. GPC model: Showa Denko Co., Ltd. Shodex GPC-101 Column: Polymer Laboratories PLgel 10μm MIXED-B Mobile phase: Tetrahydrofuran Sample concentration: 0.2% by mass Temperature: oven 40℃, injection port 35℃, detector 35℃ Detector: Differential refractometer The molecular weight in the present invention is calculated as a polystyrene-equivalent molecular weight by calculating the molecular weight at each elution time from the elution curve of monodisperse polystyrene.

[0020] Among styrene resins (A), rubber-modified styrene resins (rubber-containing styrene resins) are in the form of rubber-like dispersed particles dispersed in the matrix phase of polystyrene resin, and the molecular weight refers to the molecular weight of the matrix phase. Therefore, the sample used for molecular weight measurement is prepared by dissolving styrene resin (A) in a 50% methyl ethyl ketone / 50% acetone mixed solution, removing the rubber-like dispersed particles with a centrifuge (Kokusan H-2000B (rotor: H)), and reprecipitating the polymer in methanol. GPC model: Showa Denko Co., Ltd. Shodex GPC-101 Column: Polymer Laboratories PLgel 5μm MIXED-C Mobile phase: Tetrahydrofuran Sample concentration: 0.2% by mass Temperature: oven 40℃, injection port 35℃, detector 35℃ Detector: Differential refractometer The molecular weight in the present invention is calculated as a polystyrene-equivalent molecular weight by calculating the molecular weight at each elution time from the elution curve of monodisperse polystyrene.

[0021] The polymerization method of the styrene-based resin (A) may be a known styrene polymerization method such as bulk polymerization, solution polymerization, suspension polymerization, or emulsion polymerization. In terms of quality and productivity, bulk polymerization and solution polymerization are preferred, and continuous polymerization is preferred. As the solvent, for example, alkylbenzenes such as benzene, toluene, ethylbenzene, and xylene, ketones such as acetone and methyl ethyl ketone, and aliphatic hydrocarbons such as hexane and cyclohexane can be used.

[0022] In the case of continuous polymerization, first, a known complete mixing tank type stirring tank or tower type reactor is used in the polymerization process, and the polymerization reaction is controlled by adjusting the polymerization temperature, etc., so as to achieve the target molecular weight, molecular weight distribution, and reaction conversion rate. The polymer solution containing the polymer that has left the polymerization process is transferred to a devolatilization process, where unreacted monomers and polymerization solvent are removed. The devolatilization process is composed of a vacuum devolatilization tank equipped with a heater or a devolatilization extruder equipped with a vent. The molten polymer that has left the devolatilization process is transferred to a granulation process. In the granulation process, the molten resin is extruded in the form of strands from a multi-hole die, and processed into pellets by a cold cut method, an air hot cut method, or an underwater hot cut method.

[0023] During polymerization of the styrene-based resin (A), a polymerization initiator and a chain transfer agent can be used as necessary. As the polymerization initiator, a radical polymerization initiator is preferable, and examples of the polymerization initiator include peroxyketals such as 1,1-di(t-butylperoxy)cyclohexane, 2,2-di(t-butylperoxy)butane, 2,2-di(4,4-di-t-butylperoxycyclohexyl)propane, and 1,1-di(t-amylperoxy)cyclohexane, hydroperoxides such as cumene hydroperoxide and t-butyl hydroperoxide, alkyl peroxides such as t-butyl peroxyacetate and t-amyl peroxy isononanoate, t-butyl cumyl peroxide, di-t-butyl peroxide, dicumyl peroxide, and di-t-hexyl peroxide. Examples of the dialkyl peroxide include dialkyl peroxides such as t-butyl peroxyacetate, t-butyl peroxybenzoate, and t-butyl peroxyisopropyl monocarbonate; peroxyesters such as t-butyl peroxyisopropyl carbonate and polyether tetrakis(t-butyl peroxycarbonate); peroxycarbonates such as N,N'-azobis(cyclohexane-1-carbonitrile), N,N'-azobis(2-methylbutyronitrile), N,N'-azobis(2,4-dimethylvaleronitrile), and N,N'-azobis[2-(hydroxymethyl)propionitrile], and these may be used alone or in combination of two or more. Examples of the chain transfer agent include aliphatic mercaptans, aromatic mercaptans, pentaphenylethane, α-methylstyrene dimer, and terpinolene.

[0024] The styrene-based resin (A) preferably has an MFR (melt mass flow rate) of 3 g / 10 min or more measured at 200° C. and 49 N. There is no particular upper limit to the MFR, but it can be, for example, 35.0 g / 10 min or less, and in some cases, less than 32.0 g / 10 min. The MFR (melt mass flow rate) can be, for example, 3.0, 3.5, 4.0, 4.5, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0, 11.0, 12.0, 13.0, 14.0, 14.5, 16.0, 17.0, 18.0, 19.0, 20.0, 21.0, 22.0, 23.0, 24.0, 25.0, 26.0, 27.0, 28.0, 29.0, 30.0, 31.0, 32.0, 33.0, 34.0, or 35.0 g / 10 min, or may be within a range between any two of the values ​​exemplified here. The MFR of the styrene-based resin (A) can be measured in accordance with JIS K 7210.

[0025] <Okara (B)> The soybean lees (B) in this embodiment refers to the residue remaining after squeezing soy milk from beans. The beans in this embodiment may be of any type, but examples include soybeans, peas, chickpeas, kidney beans, fava beans, and peanuts. The soybean lees (B) may be oiled, degreased, and dried, as necessary. The moisture content of the soybean lees (B) is 0 to 20%, preferably 0.5 to 18%, from the viewpoints of processability and appearance of the molded product. It is preferable that the moisture content of the soybean lees (B) is within this range, since foaming during heating and defects in the appearance of the product can be suppressed. Specifically, for example, it may be within a range of any two of the following values: 0, 0.5, 1.0, 1.5, 2.0, 2.5, 2.6, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, and 20%.

[0026] The particle size (median size) of the okara (B) is preferably 500 μm or less, more preferably 200 μm or less, and even more preferably 100 μm or less. The particle size of the okara (B) can be measured by particle size analysis using a laser diffraction particle size distribution measuring device - laser diffraction and scattering method (ISO13320, ISO9276, JISZ8825:2013). It is preferable that the particle size of the okara (B) is within this range because it has good dispersibility in resin. The particle size of the okara (B) can be controlled by the difference in raw materials, chemical or physical modification, and conditions of chemical decomposition modification, enzyme modification, and physical modification.

[0027] <Other ingredients> Other additives may be added within a range that does not impair the object of the present invention, such as a plasticizer, a spreading agent, a solvent, an ultraviolet absorber, a light stabilizer, a stabilizer, an antistatic agent, a colorant, a dye or pigment, an organic filler, a color inhibitor, a reinforcing agent, a compatibilizer, a crystallization accelerator, a flame retardant, a flame retardant assistant, etc. In an embodiment, the styrene-based resin composition according to the present invention may contain a naturally derived material other than soybean pulp as a biomass.

[0028] In this embodiment, biomass refers to renewable organic and inorganic resources derived from living organisms, excluding fossil resources. Biomass includes organic biomass and / or inorganic biomass. Organic biomass is biomass mainly composed of solid components derived from plants and / or solid components derived from algae. Inorganic biomass is biomass mainly composed of solid components derived from an aggregate of inorganic substances (such as calcium carbonate) in a living organism. "Biomass mainly composed of solid components" refers to biomass with a moisture content of 30, 25, 20, 15, 10, 5, or 1 mass% or less. The organic biomass in this embodiment is not particularly limited, but for example, wood flour, bamboo flour, paper flour, charcoal, rice stalks, tea stalks, old rice flour, rice bran, bran, sake, shochu, beer, wine, soy sauce pomace, starch, konnyaku by-products, fruit peel or pomace, grasses including rice, wheat, and buckwheat, seaweed or algae, cotton fiber, palm fiber, or mixtures thereof can be preferably used. Cellulose, hemicellulose, lignin, etc. derived from plants can also be used as biomass. From the viewpoint of dispersibility, bamboo flour and wood flour are preferred. The inorganic biomass in this embodiment is not particularly limited, but for example, bones, eggshells, and shells can be preferably used.

[0029] In one embodiment, the styrene-based resin composition contains no more than 25, 20, 15, 10, 5, or 1 mass % of biomass other than soybean pulp. In another embodiment, the styrene-based resin composition according to the present invention does not contain any biomass other than soybean pulp.

[0030] The method of adding these is not particularly limited, and may be a known method, such as a method of adding them in a raw material charging step, a polymerization step, or a finishing step during the production of the styrene-based resin (A) or the soybean pulp (B), or a method of adding them in a step of mixing the resin composition using an extruder or a molding machine.

[0031] In one embodiment, the resin composition according to the present invention may contain an inorganic filler. Examples of the inorganic filler include baryte powder, precipitated barium sulfate, barium carbonate, lime carbonate powder, precipitated calcium carbonate, gypsum, asbestos, clay, silica powder, fine silicic acid, diatomaceous earth, talc, basic magnesium carbonate, alumina white, gloss white, satin white, zinc oxide, lead white, basic lead sulfate, litbon, zinc sulfide, titanium oxide, antimony oxide, carbon black, acetylene black, lamp black, bone black, graphite, iron black, mineral black, aniline black, cyanine black BX, yellow lead, yellow lead, barium chromate, cadmium yellow, yellow oxide. Examples of the inorganic filler include iron, ocher, titanium yellow, lead cyanamide, calcium plumbate, red yellow lead, chrome vermilion, iron oxide, amber, red iron oxide, red lead, vermilion, cadmium red, cadmium mercury red, antimony vermilion, cobalt purple, manganese purple, ultramarine, Prussian blue, cobalt blue, cerulean blue, gosu, chrome green, zinc green, chromium oxide, viridian, emerald green, cobalt green, zinc sulfide, zinc silicate, zinc cadmium sulfide, calcium sulfide, strontium sulfide, calcium tungstate, aluminum powder, bronze powder, copper powder, tin powder, lead powder, and zinc powder. The content of the inorganic filler is preferably less than 1 part by mass, more preferably less than 0.5 parts by mass, per 100 parts by mass of the resin composition.

[0032] <Methanol solubles> The methanol soluble content in okara (B) refers to the components in okara that are soluble in methanol. The methanol soluble content can be determined by precisely weighing out 1.00 g of okara (P), adding 40 ml of methyl ethyl ketone to dissolve it, and then suddenly adding 400 ml of methanol to separate and precipitate the methanol insoluble content (resin components). After leaving it to stand for about 10 minutes, it is gradually filtered through a glass filter to separate the methanol soluble content, which is then dried under reduced pressure at 125°C for 2 hours in a vacuum dryer, and then allowed to cool in a desiccator for 25 minutes. The mass N of the dried methanol insoluble content can then be measured and calculated as follows: Methanol soluble fraction (mass%) = (PN) / P x 100

[0033] The moisture content of the okara (B) can be calculated as follows: 25.00 g of okara is weighed out (Q), heated in a dryer at 110°C for 2 hours, then cooled in a desiccator for 30 minutes, and the mass M of the dried okara is measured. Moisture content (mass%)=(QM) / Q×100

[0034] <Non-petroleum derived ingredients> The non-petroleum-derived component is soybean pulp contained in the resin composition. The non-petroleum-derived component can be determined as follows. Non-petroleum-derived components (%) = Xo (mass%) / (Xs (mass%) + Xo (mass%)) x 100 Mass fraction Xs of styrene resin (A) Mass fraction of okara (B) Xo

[0035] When the resin composition contains soybean pulp and biomass other than soybean pulp, the non-petroleum-derived components can be determined as follows. Non-petroleum-derived components (%) = (Xo (mass%) + Xb (mass%)) / (Xs (mass%) + Xo (mass%) + Xb (mass%)) x 100 Mass fraction Xs of styrene resin (A) Mass fraction of okara (B) Xo Mass fraction of biomass other than soybean pulp Xb

[0036] The non-petroleum-derived component is preferably 1 to 60%, more preferably 10 to 51%. The non-petroleum-derived component in this range is preferable because it provides an excellent balance between the effect of reducing the environmental load and the processing stability. Specifically, for example, the non-petroleum-derived component may be within any two of the ranges of 1, 5, 10, 15, 20, 25, 30, 35, 40, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, and 60%.

[0037] <Manufacturing method> Next, a method for producing the resin composition of the present invention will be described.

[0038] The method for mixing the resin composition of the present invention is not particularly limited, and known mixing techniques can be applied. For example, a homogeneous resin composition can be produced by mixing various raw materials in advance using a mixing device such as a mixer-type mixer, a V-type blender, and a tumbler-type mixer, and melt-kneading the mixture. The melt-kneading device is also not particularly limited, and examples thereof include a Banbury-type mixer, a kneader, a roll, a single-screw extruder, a special single-screw extruder, and a twin-screw extruder. Furthermore, there is also a method in which other additives are added separately from the middle of a melt-kneading device such as an extruder.

[0039] The molding method for obtaining a molded article, film, sheet, or foam from the resin composition of the present invention is not particularly limited, and known molding methods such as extrusion molding methods such as calendar molding, blow molding, extrusion foam molding, profile extrusion molding, lamination molding, inflation molding, T-die film molding, sheet molding, vacuum molding, and pressure molding, and injection molding methods such as injection molding, RIM molding, and injection foam molding can be suitably used. EXAMPLES

[0040] The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to these.

[0041] The materials used in the examples and comparative examples are as follows.

[0042] [Styrene-based resin (A)] (A-1) HIPS (polystyrene resin modified with polybutadiene rubber, molecular weight (Mw) 150,000, rubber polymer content in 100% resin by mass 8% by mass, volume average particle size 2.5 μm, MFR 11 g / 10 min) (A-2) HIPS (polystyrene resin modified with polybutadiene rubber, molecular weight (Mw) 170,000, rubber polymer content in 100% resin by mass 10% by mass, volume average particle size 2.9 μm, MFR 5 g / 10 min) (A-3) HIPS (polystyrene resin modified with polybutadiene rubber, molecular weight (Mw) 230,000, rubber polymer content in 100% resin by mass 6% by mass, volume average particle size 2.7 μm, MFR 3 g / 10 min) (A-4) GPPS (polystyrene resin, molecular weight (Mw) 170,000, MFR 31g / 10min)

[0043] [Okara (B)] (B-1) Golden Okara (moisture content 11%) (manufactured by 50's Co.) (B-2) Dried okara (moisture content 4%) (manufactured by Sagamiya Foods) (B-3) Defatted soybean pulp (moisture content 2.6%) (B-4) Fat-added okara (moisture content 4%)

[0044] (B-3) Defatted okara was produced by subjecting (B-2) dried okara to a defatting treatment. (B-4) Fatted okara was produced by adding soybean oil to (B-2) dried okara.

[0045] (B-3) Defatted Okara was produced by the following method. Using a stainless steel beaker and a mechanical stirrer, 1 kg of (B-2) dried Okara was mixed with 5 kg of hexane, and filtered to obtain a residue. The residue was further mixed with 5 kg of methanol by the above method, and filtered to obtain a residue. The residue was dried in a vacuum dryer at 80°C for 12 hours to obtain (B-3) Defatted Okara.

[0046] (B-4) Fatified okara was produced by the following method: (B-2) 5 kg of dried okara and 650 g of soybean oil (Wako First Grade, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were mixed in a Henschel mixer (FM20B, manufactured by Mitsui Miike Chemical Industries, Ltd.) to produce (B-4) fattened okara.

[0047] (Examples 1 to 7, Comparative Examples 1 to 4) The components were premixed in the amounts shown in Tables 1 and 2 in a Henschel mixer (Mitsui Miike Chemical Co., Ltd., FM20B), fed to a twin-screw extruder (Toshiba Machine Co., Ltd., TEM26SS), formed into strands at a cylinder temperature of 180°C and a feed rate of 25 kg / h, cooled with water, and then fed to a pelletizer to be pelletized. The resulting pellets were injection molded, and the results of evaluation of various properties are shown in Tables 1 and 2.

[0048] [Measurement of MFR] The MFR (melt mass flow rate) of the styrene-based resin (A) was measured in accordance with JIS K 7210 under conditions of 200° C. and a load of 49 N.

[0049] [Methanol soluble matter] The methanol soluble matter was determined by precisely weighing 1.00 g of soybean pulp (B) (P), adding 40 ml of methyl ethyl ketone to dissolve it, and then adding 400 ml of methanol rapidly to separate and precipitate the methanol insoluble matter (resin component). After leaving it to stand for about 10 minutes, it was gradually filtered through a glass filter to separate the methanol soluble matter, which was then dried under reduced pressure at 125°C for 2 hours in a vacuum dryer and then allowed to cool in a desiccator for 25 minutes. The mass N of the dried methanol insoluble matter was measured and calculated as follows: Methanol soluble fraction (mass%) = (PN) / P x 100

[0050] [Non-petroleum derived ingredients] The non-petroleum derived components were calculated using the following formula: Non-petroleum-derived components = Xo (mass%) / (Xs (mass%)+Xo (mass%))×100 Mass fraction Xs of styrene resin (A) Mass fraction of okara (B) Xo

[0051] [Extrusion Stability] The extrusion stability was evaluated based on the following criteria. ◎: Can be stranded and continuously pelletized 〇: Can be stranded and pelletized intermittently ×: Cannot be stranded

[0052] [Pellet color] The pellet color was evaluated by visually inspecting the appearance of the strands obtained by twin-screw extrusion and pelletizing them with a pelletizer, according to the following criteria: "discoloration" refers to scorching of the soybean pulp, and when discoloration occurs, the pellets turn black in appearance. ◎: No fading, good color tone 〇: No fading, but some discoloration ×: Discoloration has occurred

[0053] [Measurement of Vicat softening temperature] The Vicat softening temperature was measured in accordance with JIS K 7206, at a heating rate of 50°C / hr and a test load of 50N.

[0054] [Table 1]

[0055] [Table 2]

[0056] It was found from the Examples in Table 1 that the resin compositions of the present invention are excellent in extrusion stability and pellet color, and have a high Vicat softening temperature. On the other hand, it was found from the Comparative Examples in Table 2 that the resin compositions not satisfying the provisions of the present invention are inferior in extrusion stability and pellet color, and have a low Vicat softening temperature. [Industrial Applicability]

[0057] The styrene-based resin composition according to the present invention, which contains the styrene-based resin and soybean pulp, has a low environmental impact, is excellent in color, and is excellent in heat resistance. The styrene-based resin composition according to the present invention can be suitably used as a molded product, a film, a sheet, or a foam, and has industrial applicability.

Claims

1. A styrene-based resin composition comprising a styrene-based resin (A) and okara (B), characterized in that when the total amount of the styrene-based resin (A) and okara (B) is 100 parts by mass, it contains 25 to 97 parts by mass of the styrene-based resin (A) and 3 to 75 parts by mass of the okara (B), and the methanol-soluble content of the okara (B) is 7 to 25% by mass.

2. The styrene resin composition according to claim 1, wherein the styrene resin (A) is a rubber-containing styrene resin.

3. The styrene-based resin composition according to claim 1, wherein the melt mass flow rate of the styrene-based resin (A), measured at 200°C and 49N, is 3 g / 10 min or more.

4. A molded article comprising the styrene-based resin composition described in any one of claims 1 to 3.

5. A film comprising the styrene-based resin composition according to any one of claims 1 to 3.

6. A sheet comprising the styrene-based resin composition according to any one of claims 1 to 3.

7. A foam comprising the styrene-based resin composition according to any one of claims 1 to 3.