Graphene-containing thermoplastic resin composition and method for producing the same

Abstract

The present invention provides a graphene-containing thermoplastic resin composition that can improve the dispersibility of graphene even with a small amount of graphene, thereby reducing manufacturing costs, improving electrical conductivity, and also improving moldability. [Solution] The graphene-containing thermoplastic resin composition according to the present disclosure is a graphene-containing thermoplastic resin composition containing a thermoplastic resin (A), graphene (B), a dispersant (C), and a nonionic surfactant (D), wherein when the total mass of the graphene-containing thermoplastic resin composition is 100% by mass, the thermoplastic resin (A) is 37 to 99.8% by mass, graphene (B) is 0.1 to 3% by mass, the dispersant (C) is 0.1 to 30% by mass, and the nonionic surfactant (D) is 0 to 30% by mass, and the dispersant (C) is a compound having a trimer or more and an aromatic sulfonate structure.

Description

Technical Field

[0001] The present invention relates to a graphene-containing thermoplastic resin composition and a method for producing the same.

Background Art

[0002] A graphene sheet, which is one of the nanocarbon materials, has a two-dimensional single-layer structure in which carbon atoms are arranged in a honeycomb lattice, and due to its unique physical properties (Young's modulus of 1.0 TPa, carrier mobility of 200000 cm 2 / (V·s), electrical conductivity of 30 Ω / □, thermal conductivity of 5000 W / (m·K), etc.), it is expected as a new material.

[0003] As a conventional graphene-containing thermoplastic resin composition, for example, a resin composition containing a synthetic resin and a laminated body of graphene sheets, the number of laminated layers is 150 or less and the aspect ratio is 20 or more, is disclosed (Patent Document 1). The synthetic resin sheet obtained from this resin composition is said to have high mechanical strength, specifically, a high tensile elastic modulus and a low linear expansion coefficient.

[0004] As another conventional carbon substance-containing resin composition, a resin composition containing 80 to 99.9 parts by weight of a thermoplastic resin and 0.1 to 20 parts by weight of a carbon nanomaterial containing a polycyclic aromatic hydrocarbon derivative is disclosed (Patent Document 2).

[0005] Furthermore, as still another conventional carbon substance-containing resin composition, a thermoplastic polymer containing 0.1 to 15% by weight of a carbon nanomaterial, 0.025 to 30% by weight of a polycyclic aromatic hydrocarbon derivative, and 55 to 99.875% by weight of a thermoplastic polymer is disclosed, wherein the carbon nanomaterial and the polycyclic aromatic hydrocarbon derivative are bonded by π-π interaction, and the polycyclic aromatic hydrocarbon derivative is bonded to the thermoplastic polymer by a covalent bond (Patent Document 3).

[0006] In the examples described in Patent Documents 2 and 3, polyamide resin is used as the thermoplastic resin, carbon nanotubes (MWNTs) as the carbon nanomaterial, and pyrene derivatives (PBA or PBC) as the polycyclic aromatic hydrocarbon derivatives. The resulting molded articles are said to exhibit excellent tensile strength, tensile modulus, antistatic effect, and electromagnetic shielding effect. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Patent No. 5869792 [Patent Document 2] Patent No. 5989914 [Patent Document 3] Patent No. 6076484 [Overview of the project] [Problems that the invention aims to solve]

[0008] However, graphene tends to form aggregates, making it difficult to obtain single-layer graphene sheets (monolayers of graphite) or thin, transparent multilayer graphene. Therefore, dispersing graphene in graphene-containing thermoplastic resin compositions is difficult, and a large amount of graphene needs to be added to improve electrical conductivity. Consequently, there is still room for improvement in terms of moldability, electrical conductivity, and manufacturing costs.

[0009] The present invention aims to provide a graphene-containing thermoplastic resin composition and a method for producing the same, which can improve the dispersibility of graphene even with a small amount of graphene, reduce manufacturing costs, improve electrical conductivity, and further improve moldability. [Means for solving the problem]

[0010] As a result of diligent research, the present inventors have found that in a graphene-containing thermoplastic resin composition containing a thermoplastic resin (A), graphene (B), a dispersant (C), and a nonionic surfactant (D), when the oil content of graphene (B) in the graphene-containing thermoplastic resin composition is 0.1 to 7% by mass, the content of the dispersant (C) is 0.1 to 40% by mass, and furthermore, when the dispersant (C) is a compound having a trimer or more and an aromatic sulfonate structure, the aggregation of graphene in the resin is suppressed, and single-layer graphene or transparent thin-layer multilayer graphene can be peeled from graphene aggregates or multilayer graphene. As a result, even if only a small amount of graphene is contained in the resin composition, the dispersibility of graphene is improved, and electrical conductivity can be improved while reducing manufacturing costs. Furthermore, the present inventors have found that by using the graphene-containing thermoplastic resin composition of the present invention, molded articles can be easily manufactured using equipment such as a twin-screw extruder without requiring excessive conditions, thereby improving moldability. Furthermore, we found that by further including a nonionic surfactant (D) in the graphene-containing thermoplastic resin composition, the re-aggregation of the detached single-layer graphene can be prevented, and the electrical conductivity can be further improved by better dispersibility of the graphene.

[0011] In other words, the present invention provides the following configuration. [1] A graphene-containing thermoplastic resin composition comprising a thermoplastic resin (A), graphene (B), a dispersant (C), and a nonionic surfactant (D), When the total mass of the graphene-containing thermoplastic resin composition is taken as 100% by mass, the thermoplastic resin (A) is 37-99.8% by mass, the graphene (B) is 0.1-7% by mass, the dispersant (C) is 0.1-40% by mass, and the nonionic surfactant (D) is 0-30% by mass. A graphene-containing thermoplastic resin composition in which the dispersant (C) is a compound having a trimer or more and an aromatic sulfonate structure.

[0012] [2] The graphene-containing thermoplastic resin composition according to [1], wherein the counterion in the aromatic sulfonate structure of the dispersant (C) is a monovalent cation other than a hydrogen ion.

[0013] [3] The graphene-containing thermoplastic resin composition according to [1], wherein the nonionic surfactant (D) has a polyether structure.

[0014] A molded article which is a melt-molded article of the graphene-containing thermoplastic resin composition described in [4] [1] or [2].

[0015] [5] A method for producing a graphene-containing thermoplastic resin composition, comprising the step of mixing a thermoplastic resin (A), graphene (B), a dispersant (C), and a nonionic surfactant (D), and melt-kneading them at a temperature above the melting point of the thermoplastic resin (A), When the total mass of the graphene-containing thermoplastic resin composition is taken as 100% by mass, the thermoplastic resin (A) is 37-99.8% by mass, the graphene (B) is 0.1-7% by mass, the dispersant (C) is 0.1-40% by mass, and the nonionic surfactant (D) is 0-30% by mass. A method for producing a graphene-containing thermoplastic resin composition, wherein the dispersant (C) is a compound having a trimer or more and an aromatic sulfonate structure.

[0016] [6] Prepare an aqueous dispersion of graphene (B), A method for producing the graphene-containing thermoplastic resin composition according to [5], comprising mixing the thermoplastic resin (A), an aqueous dispersion of graphene (B), the dispersant (C), and the nonionic surfactant (D).

[0017] [7] A method for producing a graphene-containing thermoplastic resin composition according to [5] or [6], wherein the counterion in the aromatic sulfonate structure of compound (C) is a monovalent cation other than a hydrogen ion.

[0018] [8] The method for producing a graphene-containing thermoplastic resin composition according to [5], wherein the nonionic surfactant (D) has a polyether structure.

[0019] [9] A method for producing a molded body, comprising a step of melt-molding the graphene-containing thermoplastic resin composition obtained by the production method according to [5].

Advantages of the Invention

[0020] According to the present disclosure, it is possible to provide a graphene-containing thermoplastic resin composition that solves the above problems. Even when the amount of graphene is small, the dispersibility of graphene can be improved, the manufacturing cost can be reduced, and the electrical conductivity can be improved while improving the moldability.

Brief Description of the Drawings

[0021] [Figure 1] FIG. 1 is a partially enlarged view of an optical microscope image of the graphene-containing plastic resin composition obtained in Example 2. [Figure 2] FIG. 2 is a partially enlarged view of an optical microscope image of the graphene-containing plastic resin composition obtained in Example 3. [Figure 3] FIG. 3 is a partially enlarged view of an optical microscope image of the graphene-containing plastic resin composition obtained in Comparative Example 1. [Figure 4] FIG. 4 is a diagram showing the WAXD analysis results of the graphene-containing plastic resin compositions obtained in Example 2 and Comparative Example 1. [Figure 5] FIG. 5 is a diagram showing the volume resistivity of the molded bodies obtained in Examples 5 to 8 and Comparative Examples 3 to 4.

Modes for Carrying Out the Invention

[0022] An embodiment of the present invention will be described below with reference to the drawings, but the scope of the present invention is not limited to the embodiment described herein, and various modifications can be made without departing from the spirit of the invention. Furthermore, if multiple upper and lower limits are given for a particular parameter, any combination of these upper and lower limits can be used to create a suitable numerical range.

[0023] <Graphene-containing thermoplastic resin composition> The graphene-containing thermoplastic resin composition of this embodiment is a graphene-containing thermoplastic resin composition containing a thermoplastic resin (A), graphene (B), a dispersant (C), and a nonionic surfactant (D), wherein when the total mass of the graphene-containing thermoplastic resin composition is 100% by mass, the thermoplastic resin (A) is 37 to 99.8% by mass, graphene (B) is 0.1 to 7% by mass, the dispersant (C) is 0.1 to 40% by mass, and the nonionic surfactant (D) is 0 to 30% by mass, and the dispersant (C) is a compound having a trimer or more and an aromatic sulfonate structure.

[0024] (Thermoplastic resin (A)) The thermoplastic resin (A) is not particularly limited as long as it is a thermoplastic resin, and is, for example, one or more selected from polyester resins, polyamide resins, polyacrylate resins, polyketone resins, polyvinyl resins, polystyrene resins, polyolefin resins, and polyphenylene ether resins.

[0025] Examples of the polyester resins mentioned above include one or more selected from polylactic acid, polycarbonate, polyester, polybutylene terephthalate, polyethylene terephthalate, poly(ester)urethane, and polyether ester. Of these, polylactic acid is preferred from the viewpoint of biodegradability.

[0026] Examples of the polyamide resins mentioned above include one or more selected from polyamides, polyimides, and polyether esteramides. The polyamide may be one or more selected from nylon 4.6, nylon 5.6, nylon 5.10, nylon 6, nylon 6.6, nylon 6.10, nylon 7, nylon 8, nylon 9, nylon 11, nylon 12, MXD6, amorphous polyamides, and copolymerized polyamides. The copolymerized polyamide may, for example, be a copolymer polymerized containing monomers of two or more polyamides from the remaining polyamides mentioned above.

[0027] Examples of the polyacrylate-based resins mentioned above include either or both of polyacrylate and polymethyl methacrylate.

[0028] Examples of the polyketone-based resins mentioned above include either or both of polyaryletherketone and polyetheretherketone.

[0029] Examples of the polyvinyl resins mentioned above include either or both of polyvinyl chloride and polyvinylidene fluoride.

[0030] Examples of the polystyrene-based resins mentioned above include one or more selected from polystyrene, styrene-butadiene-styrene copolymer, styrene-isoprene-styrene copolymer, styrene-ethylene-butadiene-styrene copolymer, and styrene-butadiene copolymer.

[0031] The content of thermoplastic resin (A) is preferably 37.0 to 99.8% by mass, more preferably 40.0 to 89.75% by mass, and more preferably 52.0 to 82.5% by mass, when the total mass of the graphene-containing thermoplastic resin composition is taken as 100% by mass.

[0032] (Graphene (B)) Graphene (B) is sp 2It contains monolayer graphene with a thickness of one carbon atom, in which bonded carbon atoms are arranged in a hexagonal honeycomb lattice. The graphene (B) of this embodiment may contain monolayer graphene, may have monolayer graphene as its main component, or may consist of monolayer graphene. Furthermore, graphene (B) may contain multilayer graphene, or may contain derivatives of monolayer graphene and / or multilayer graphene. The content of single-layer graphene in graphene (B) is preferably 90.0% by mass or more, preferably 95.0% by mass or more, and more preferably 98.0% by mass or more.

[0033] The size of graphene(B) is not particularly limited, but for example, its thickness is 1.0 nm to 50.0 nm and its diameter at the maximum length equivalent to a circle is 1.0 μm to 10.0 μm. The thickness of graphene(B) can be measured by an atomic force microscope (AFM), and its diameter can be measured by an optical microscope or a transmission electron microscope (TEM).

[0034] The graphene (B) content is preferably 0.1 to 7.0% by mass, more preferably 0.25 to 5.0% by mass, and more preferably 0.5 to 3.0% by mass, when the total mass of the graphene-containing thermoplastic resin composition is taken as 100% by mass.

[0035] (Dispersant (C)) The dispersant (C) in this embodiment is not particularly limited as long as it is a compound having trimers or more and an aromatic sulfonate structure. By having a dispersant (C) that is a compound having trimers or more and an aromatic sulfonate structure, it is possible to detach single-layer graphene or transparent thin-layer multilayer graphene from graphene aggregates or multilayer graphene, and the volume resistivity can be reduced with a small amount of graphene added.

[0036] The dispersant (C) is a compound having an aromatic sulfonate structure as a repeating unit, and is typically an oligomer or polymer. The number-average molecular weight of the dispersant (C) is not particularly limited, but is preferably 200 to 20,000, more preferably 600 to 13,000, and even more preferably 1,000 to 10,000.

[0037] Examples of dispersants (C) include copolymers of dihydroxydiphenyl sulfone and sulfonate compounds such as phenol sulfonates, naphthalene sulfonate-formaldehyde condensate polymers obtained by condensing naphthalene sulfonate compounds with formaldehyde, and polymers of styrene sulfonates obtained by sulfonation of polystyrene, selected from these options.

[0038] Examples of aromatic sulfonate structures include one or more selected from alkylbenzene sulfonates, alkylnaphthalene sulfonates, phenol sulfonates, and styrene sulfonates.

[0039] The counterion in the aromatic sulfonate structure of the dispersant (C) is preferably a monovalent cation other than a hydrogen ion. The monovalent cation other than a hydrogen ion is not particularly limited, but examples include one or more selected from sodium ions, lithium ions, potassium ions, and ammonium ions.

[0040] The content of the dispersant (C) is preferably 0.1 to 40.0% by mass, more preferably 5.0 to 35.0% by mass, and more preferably 10.0 to 30.0% by mass, when the total mass of the graphene-containing thermoplastic resin composition is taken as 100% by mass.

[0041] (Nonionic surfactant (D)) The nonionic surfactant (D) is not particularly limited as long as it is a nonionic surfactant, but it is preferable that it has a polyether structure. The polyether structure has a main chain in which multiple ether bonds are repeated. The presence of a polyether structure in the nonionic surfactant (D) prevents the re-aggregation of exfoliated graphene, thereby achieving better dispersibility.

[0042] The number-average molecular weight of the nonionic surfactant (D) is not particularly limited, but is preferably 200 to 20,000, more preferably 600 to 13,000, and even more preferably 100 to 10,000.

[0043] Examples of the nonionic surfactant (D) include one or more selected from polyethylene glycol, polypropylene glycol, polytetraethylene glycol, polyoxyethylene polyoxypropylene glycol, and polyoxyethylene sorbitan monooleate.

[0044] The content of the nonionic surfactant (D) is preferably 0.1 to 30.0% by mass, more preferably 5.0 to 20.0% by mass, and even more preferably 7.0 to 15.0% by mass, when the total mass of the graphene-containing thermoplastic resin composition is taken as 100% by mass.

[0045] (Other ingredients) The graphene-containing thermoplastic resin composition of this embodiment contains a thermoplastic resin (A), graphene (B), and a dispersant (C) as essential components, and is also assumed to contain a nonionic surfactant (D) as an optional component, and may contain other components as well. For example, the graphene-containing thermoplastic resin composition may contain one or more types of fiber materials or particles for the purpose of imparting other properties such as mechanical properties and optical properties in addition to electrical conductivity.

[0046] <Molded body> The molded article according to this embodiment is a melt-molded product of the graphene-containing thermoplastic resin composition described above. The molded article is not particularly limited, but examples include sheets and films.

[0047] (Sheet) The sheet of this embodiment is obtained by forming the above-described graphene-containing thermoplastic resin composition into a sheet. Alternatively, the sheet may be obtained by mixing a masterbatch composed of the above-described graphene-containing thermoplastic resin composition with another thermoplastic resin to obtain a graphene-containing thermoplastic resin composition, and then forming this into a sheet.

[0048] The sheet contains a thermoplastic resin (A), graphene (B), and a dispersant (C) as essential components, and a nonionic surfactant (D) as an optional component. The types and amounts of each component constituting the sheet can be the same as those of each component constituting the graphene-containing thermoplastic resin composition described above. Furthermore, the sheet may contain one or more other components, provided that it contains a thermoplastic resin (A), graphene (B), and a dispersant (C).

[0049] The sheet of this embodiment has a volume resistivity of 1.0 × 10 10 It is preferable that it be Ω·m or less, and 1.0 × 10 9 It is more preferable that it be Ω·m or less, and 5.0 × 10 8 It is even more preferable that it be less than or equal to Ω·m.

[0050] (film) The film of this embodiment is obtained by forming the above-mentioned graphene-containing thermoplastic resin composition into a film. The film may also be obtained by mixing a masterbatch composed of the above-mentioned graphene-containing thermoplastic resin composition with another thermoplastic resin to obtain a graphene-containing thermoplastic resin composition, and then forming this into a film.

[0051] The film contains a thermoplastic resin (A), graphene (B), and a dispersant (C) as essential components, and a nonionic surfactant (D) as an optional component. The types and amounts of each component constituting the film can be the same as those of each component constituting the graphene-containing thermoplastic resin composition described above. Furthermore, the film may contain one or more other components, provided that it contains a thermoplastic resin (A), graphene (B), and a dispersant (C).

[0052] <Method for producing a graphene-containing thermoplastic resin composition> The method for producing the graphene-containing thermoplastic resin composition of this embodiment is a method for producing a graphene-containing thermoplastic resin composition comprising the step of mixing a thermoplastic resin (A), graphene (B), a dispersant (C), and a nonionic surfactant (D), and melt-kneading them at a temperature above the melting point of the thermoplastic resin (A), wherein, based on 100% by mass of the graphene-containing thermoplastic resin composition, the thermoplastic resin (A) is 37 to 99.8% by mass, graphene (B) is 0.1 to 7% by mass, the dispersant (C) is 0.1 to 40% by mass, and the nonionic surfactant (D) is 0 to 30% by mass, and the dispersant (C) is a compound having a trimer or more and an aromatic sulfonate structure.

[0053] In the above process, a thermoplastic resin (A), graphene (B), a dispersant (C), and a nonionic surfactant (D) are blended in the above-described predetermined ratio, and the mixture is melt-kneaded at a temperature above the melting point of the thermoplastic resin (A). By melt-kneading the above mixture at a temperature above the melting point of the thermoplastic resin (A), the dispersibility of graphene (B) in the graphene-containing thermoplastic resin composition can be improved. If the thermoplastic resin (A) is composed of multiple types of thermoplastic resins, it is preferable to select the highest melting point from among the multiple types of thermoplastic resins and melt-knead them at a temperature above that melting point.

[0054] The method for melt-kneading the above mixture is not particularly limited as long as the melt-kneading can be performed while controlling the temperature, and can be carried out using known equipment such as a twin-screw extruder.

[0055] The thermoplastic resin (A) used in the above process is not particularly limited as long as it is a thermoplastic resin, and is, for example, one or more selected from polyester resins, polyamide resins, polyacrylate resins, polyketone resins, polyvinyl resins, polystyrene resins, polyolefin resins, and polyphenylene ether resins. Specific examples of the thermoplastic resin (A) can be the same as those described above.

[0056] The graphene (B) used in the above process may contain monolayer graphene, have monolayer graphene as its main component, or consist of monolayer graphene. Furthermore, the graphene (B) used in the above process may contain multilayer graphene, or contain monolayer graphene and / or derivatives of multilayer graphene.

[0057] In the manufacturing method of this embodiment, a step of preparing an aqueous dispersion of graphene (B) may be further included before the above step. In this case, a thermoplastic resin (A), an aqueous dispersion of graphene (B), a dispersant (C), and a nonionic surfactant (D) are mixed. By mixing graphene (B) as an aqueous dispersion with the thermoplastic resin (A), dispersant (C), and nonionic surfactant (D), the dispersibility of graphene (B) in the graphene-containing thermoplastic resin composition can be further improved.

[0058] The graphene (B) content of the above aqueous dispersion, when the total mass is 100% by mass, is not particularly limited, but is preferably 1.0 to 20.0% by mass, more preferably 3.0 to 15.0% by mass, and even more preferably 4.0 to 10.0% by mass.

[0059] The dispersant (C) used in the above process is a compound having a trimer or more and an aromatic sulfonate structure. Specific examples of the dispersant (C) can be those with the same composition as described above.

[0060] The counterion in the aromatic sulfonate structure of compound (C) used in the above process is preferably a monovalent cation other than a hydrogen ion. Specific examples of monovalent cations other than hydrogen ions include those with the same configuration as described above.

[0061] In the above process, a thermoplastic resin (A), graphene (B), a dispersant (C), and a nonionic surfactant (D) may be blended as essential components in the predetermined ratios described above, and the mixture may be melt-kneaded at a temperature above the melting point of the thermoplastic resin (A). The nonionic surfactant (D) used in the above process preferably has a polyether structure. Specific examples of the nonionic surfactant (D) include those with the same configuration as described above.

[0062] In the above process, assuming that the thermoplastic resin (A), graphene (B), and dispersant (C) are mixed, other components may be added. The other components may be mixed together with the thermoplastic resin (A), graphene (B), and dispersant (C) when they are mixed, or they may be mixed after the thermoplastic resin (A), graphene (B), and dispersant (C) have been mixed. Specific examples of other components can be the same as those described above.

[0063] <Method for manufacturing molded articles> The method for manufacturing a molded article according to this embodiment includes a step of melt-molding the graphene-containing thermoplastic resin composition obtained by the above manufacturing method. For example, when a sheet is to be formed by melt molding as a molded body, the graphene-containing thermoplastic resin composition obtained by the above manufacturing method is formed into a sheet. The method of forming the sheet is not particularly limited, but examples include hot pressing, single-layer or multi-layer inflation, and T-die. Alternatively, the sheet may be formed by mixing a masterbatch composed of the above graphene-containing thermoplastic resin composition with another thermoplastic resin to obtain a graphene-containing thermoplastic resin composition, and then forming this into a sheet.

[0064] The graphene-containing thermoplastic resin composition and molded article according to this embodiment can be produced by the above-described method for producing the graphene-containing thermoplastic resin composition and the method for producing the molded article. [Examples]

[0065] The present invention will now be described in more detail with reference to the following examples. The present invention is not limited to the following examples.

[0066] <<Preparation and Evaluation of Graphene-Containing Thermoplastic Resin Compositions>> (Example 1) A graphene-containing thermoplastic resin composition was obtained by melt-kneading 96.9% by mass of polylactic acid (Unitika Corporation, TP-4000), 0.1% by mass of an aqueous dispersion of multilayer graphene (Osaka Gas Co., Ltd., G1103, graphene concentration 4.6% by mass), and 3.0% by mass of a water-soluble phenolic resin (Konishi Chemical Industry Co., Ltd., WSR-SP82, concentration 31.0-34.0% by mass) at 200°C using Laboplastmill® (registered trademark) (Toyo Seiki Co., Ltd., R60).

[0067] (Example 2) A graphene-containing thermoplastic resin composition was obtained by melt-kneading 93.9% by mass of polylactic acid (Unitika Corporation, TP-4000), 0.1% by mass of a multilayer graphene aqueous dispersion (Osaka Gas Co., Ltd., G1103, graphene concentration 4.6% by mass), 3.0% by mass of a water-soluble phenolic resin (Konishi Chemical Industry Co., Ltd., WSR-SP82, concentration 31.0-34.0% by mass), and 3.0% by mass of polyethylene glycol (Sanyo Chemical Industries, Ltd., PEG600) at 200°C using a Laboplast Mill (Toyo Seiki Co., Ltd.: R60).

[0068] (Example 3) A graphene-containing thermoplastic resin composition was obtained by melt-kneading 91.9% by mass of polylactic acid (Unitika Corporation, TP-4000), 0.1% by mass of a multilayer graphene aqueous dispersion (Osaka Gas Co., Ltd., G1103, graphene concentration 4.6% by mass), 5% by mass of condensed naphthalene sulfonate sodium salt (Senka Co., Ltd., Semol WS100), and 3.0% by mass of polyethylene glycol (Sanyo Chemical Industries, Ltd., PEG600) at 200°C using a Laboplast Mill (Toyo Seiki Co., Ltd., R60).

[0069] (Comparative Example 1) A graphene-containing thermoplastic resin composition was obtained by melt-kneading 99.9% by mass of polylactic acid (Unitika Corporation, TP-4000) and 0.1% by mass of an aqueous dispersion of multilayer graphene (Osaka Gas Co., Ltd.: G1103, graphene concentration 4.6% by mass) at 200°C using a Laboplast Mill (Toyo Seiki Co., Ltd.: R60).

[0070] (Comparative Example 2) A graphene-containing thermoplastic resin composition was obtained by melt-kneading 96.9% by mass of polylactic acid (Unitika Corporation, TP-4000), 0.1% by mass of an aqueous dispersion of multilayer graphene (Osaka Gas Co., Ltd., G1103, graphene concentration 4.6% by mass), and 3.0% by mass of sodium dodecylbenzenesulfonate (Kao Corporation, Neoperex G-65, concentration 65% by mass) at 200°C using a Laboplast Mill (Toyo Seiki Co., Ltd., R60).

[0071] <Rating> [Variable Evaluation] The graphene-containing plastic resin compositions obtained in Examples 1-3 and Comparative Examples 1-2 were observed using an optical microscope. The optical magnification was set to 200x. [Evaluation Criteria] If transparent small and large particles are detected... Good "〇" If many small, transparent particles are observed... Good (◎) If almost no transparent particles are observed, and many black particles are observed... it is defective ("×").

[0072] [WAXD Analysis] The graphene-containing plastic resin compositions obtained in Example 2 and Comparative Example 1 were kneaded and pressed to a thickness of approximately 1 mm at 190°C, and then rapidly cooled in ice water to prepare sheet samples of approximately 1 mm thickness. An X-ray diffractometer (Rigaku Corporation, SmartLab 9kW) was used to measure the presence or absence of diffraction peaks (2θ=26.5°) caused by the interlayer distance of the original multilayer graphene under the following measurement conditions. For reference, the graphene aqueous dispersion was measured using an anti-reflective sample plate. The results are shown in Table 1.

[0073] (Measurement conditions) Cu-K Using alpha rays 2θ / θ method: 2θ = 5 to 40 degrees. step = 0.02deg. speed = 2.0 degrees / min.

[0074] [Table 1]

[0075] In Example 1, a large number of both large and small transparent particles were observed, while in Example 3, a large number of small transparent particles were observed. As representative examples, Figures 1 and 2 show magnified sections of electron microscope images of the graphene-containing plastic resin compositions obtained in Examples 2 and 3.

[0076] On the other hand, in both Comparative Examples 1 and 2, no transparent particles were observed, and only a large number of black particles were found. As a representative example, Figure 3 shows a magnified portion of the optical microscope image of the graphene-containing plastic resin composition obtained in Comparative Example 1.

[0077] Furthermore, as shown in Figure 4, in Example 2, when 3.0% by mass of water-soluble phenolic resin as dispersion (C) was contained in the graphene-containing thermoplastic resin composition, no diffraction peaks due to the interlayer distance of multilayer graphene were detected around 2θ = 26.5°, indicating that interlayer delamination of multilayer graphene occurred and single-layer graphene was generated. On the other hand, in Comparative Example 1, when the graphene-containing thermoplastic resin composition did not contain dispersion (C), a diffraction peak due to the interlayer distance of the multilayer graphene was clearly detected around 2θ = 26.5°, indicating that interlayer delamination of the multilayer graphene had not occurred.

[0078] <<Fabrication and Evaluation of Molded Products>> (Example 4) A graphene-containing thermoplastic resin composition was prepared by melt-kneading 94.5% by mass of polylactic acid (Unitika Corporation, TP-4000), 0.5% by mass of an aqueous dispersion of multilayer graphene (Osaka Gas Co., Ltd., G1103, graphene concentration 4.6% by mass), and 5.0% by mass of a water-soluble phenolic resin (Konishi Chemical Industry Co., Ltd., WSR-SP82, concentration 31.0-34.0% by mass) at 200°C using a Laboplast Mill (Toyo Seiki Co., Ltd., R60). The obtained graphene-containing thermoplastic resin composition was prepared by hot pressing, and after washing the surface with pure water, a sheet was obtained by air drying for 3 days.

[0079] (Example 5) A graphene-containing thermoplastic resin composition was prepared by melt-kneading 84.5% by mass of polylactic acid (Unitika Corporation, TP-4000), 0.5% by mass of an aqueous dispersion of multilayer graphene (Osaka Gas Co., Ltd., G1103, graphene concentration 4.6% by mass), and 15% by mass of condensed sodium naphthalene sulfonate (Senka Co., Ltd., Semol WS100) at 200°C using a Laboplast Mill (Toyo Seiki Co., Ltd., R60). The obtained graphene-containing thermoplastic resin composition was prepared by hot pressing, and after washing the surface with pure water, a sheet was obtained by air drying for 3 days.

[0080] (Example 6) A graphene-containing thermoplastic resin composition was prepared by melt-kneading 69.0% by mass of polylactic acid (Unitika Corporation, TP-4000), 1.0% by mass of an aqueous dispersion of multilayer graphene (Osaka Gas Co., Ltd., G1103, graphene concentration 4.6% by mass), and 30.0% by mass of condensed sodium naphthalene sulfonate (Senka Co., Ltd., Semol WS100) at 200°C using a Laboplast Mill (Toyo Seiki Co., Ltd., R60). The obtained graphene-containing thermoplastic resin composition was prepared by hot pressing, and after washing the surface with pure water, a sheet was obtained by air drying for 3 days.

[0081] (Example 7) A graphene-containing thermoplastic resin composition was prepared by melt-kneading 59.0% by mass of polylactic acid (Unitika Corporation, TP-4000), 1.0% by mass of a multilayer graphene aqueous dispersion (Osaka Gas Co., Ltd., G1103, graphene concentration 4.6% by mass), 30.0% by mass of condensed naphthalene sulfonate sodium salt (Senka Co., Ltd., Semol WS100), and 10.0% by mass of polyethylene glycol (Sanyo Chemical Industries, Ltd., PEG600) at 200°C using a Laboplast Mill (Toyo Seiki Co., Ltd., R60). The obtained graphene-containing thermoplastic resin composition was prepared by hot pressing, and after washing the surface with pure water, a sheet was obtained by air drying for 3 days.

[0082] (Example 8) A graphene-containing thermoplastic resin composition was prepared by melt-kneading 59.0% by mass of polylactic acid (Unitika Corporation, TP-4000), 1.0% by mass of an aqueous dispersion of multilayer graphene (Osaka Gas Co., Ltd., G1103, graphene concentration 4.6% by mass), 30% by mass of sodium salt of polystyrene sulfonic acid-maleic acid copolymer (Nurion Co., Ltd., Narlex D-72), and 10.0% by mass of polyethylene glycol (Sanyo Chemical Industries, Ltd., PEG600) at 200°C using a Laboplast Mill (Toyo Seiki Co., Ltd., R60). The obtained graphene-containing thermoplastic resin composition was prepared by hot pressing, and after washing the surface with pure water, a sheet was obtained by air drying for 3 days.

[0083] (Comparative Example 3) A graphene-containing thermoplastic resin composition was prepared by melt-kneading 99.0% by mass of polylactic acid (Unitika Corporation, TP-4000) and 1.0% by mass of an aqueous dispersion of multilayer graphene (Osaka Gas Co., Ltd., G1103, graphene concentration 4.6% by mass) at 200°C using a Laboplast Mill (Toyo Seiki Co., Ltd., R60). The obtained graphene-containing thermoplastic resin composition was prepared by hot pressing, and after washing the surface with pure water, sheets were obtained by air drying for 3 days. The volume resistivity of the obtained sheets was measured.

[0084] (Comparative Example 4) A graphene-containing thermoplastic resin composition was prepared by melt-kneading 69.0% by mass of polylactic acid (Unitika Corporation, TP-4000), 1.0% by mass of an aqueous dispersion of multilayer graphene (Osaka Gas Co., Ltd., G1103, graphene concentration 4.6% by mass), and 30.0% by mass of sodium dodecylbenzenesulfonate (Kao Corporation, Neoperex G-65, concentration 65.0% by mass) at 200°C using a Laboplast Mill (Toyo Seiki Co., Ltd., R60). The obtained graphene-containing thermoplastic resin composition was prepared by hot pressing, and a sheet was obtained by washing the surface with pure water and air-drying for 3 days. The volume resistivity of the obtained sheet was measured.

[0085] <Rating> [Volume resistivity] Using a high resistivity meter (Nitto Seiko Analytech Co., Ltd., High Resista UP MCP-HT450 model), the volume resistivity of the sheets obtained in Examples 4-8 and Comparative Examples 3-4 was measured using the double-ring method under conditions of room temperature 23°C, humidity 50%, applied voltage 10V, and application time 60 seconds. However, for Comparative Example 3, the applied voltage was changed to 1000V due to its high volume resistivity. The results are shown in Table 2 and Figure 5.

[0086] [Table 2]

[0087] From the results in Table 2, in Examples 4 to 8, the graphene (B) content in the graphene-containing thermoplastic resin composition was 0.1 to 7% by mass, and the dispersant (C) content was 0.1 to 40% by mass. Furthermore, when the dispersant (C) is a compound having a trimer or more and an aromatic sulfonate structure, the volume resistivity was 3.1 × 10⁻⁶. 8 It was found that the impedance becomes less than Ω·m, resulting in high electrical conductivity. Furthermore, in Example 7, it was found that the volume resistivity could be further reduced by further including the nonionic surfactant (D) compared to Example 6, which did not contain the nonionic surfactant (D).

[0088] On the other hand, in Comparative Example 3, the graphene-containing thermoplastic resin composition did not contain a dispersant (C) and a nonionic surfactant (D), resulting in high volume resistivity and poor electrical conductivity. In Comparative Example 4, the dispersant (C) was sodium dodecylbenzenesulfonate, which had high volume resistivity and poor electrical conductivity.

Claims

1. A graphene-containing thermoplastic resin composition comprising a thermoplastic resin (A), graphene (B), a dispersant (C), and a nonionic surfactant (D), When the total mass of the graphene-containing thermoplastic resin composition is 100% by mass, the thermoplastic resin (A) is 37 to 99.8% by mass, the graphene (B) is 0.1 to 7% by mass, the dispersant (C) is 0.1 to 40% by mass, and the nonionic surfactant (D) is 0 to 30% by mass. A graphene-containing thermoplastic resin composition in which the dispersant (C) is a compound having a trimer or more and an aromatic sulfonate structure.

2. The graphene-containing thermoplastic resin composition according to claim 1, wherein the counterion in the aromatic sulfonate structure of the dispersant (C) is a monovalent cation other than a hydrogen ion.

3. The graphene-containing thermoplastic resin composition according to claim 1, wherein the nonionic surfactant (D) has a polyether structure.

4. A molded article which is a melt-molded article of the graphene-containing thermoplastic resin composition according to claim 1 or 2.

5. A method for producing a graphene-containing thermoplastic resin composition, comprising the steps of mixing a thermoplastic resin (A), graphene (B), a dispersant (C), and a nonionic surfactant (D), and melt-kneading them at a temperature above the melting point of the thermoplastic resin (A), When the total mass of the graphene-containing thermoplastic resin composition is 100% by mass, the thermoplastic resin (A) is 37 to 99.8% by mass, the graphene (B) is 0.1 to 7% by mass, the dispersant (C) is 0.1 to 40% by mass, and the nonionic surfactant (D) is 0 to 30% by mass. A method for producing a graphene-containing thermoplastic resin composition, wherein the dispersant (C) is a compound having a trimer or more and an aromatic sulfonate structure.

6. Prepare the aqueous dispersion of graphene (B) as described above. A method for producing a graphene-containing thermoplastic resin composition according to claim 5, comprising mixing the thermoplastic resin (A), an aqueous dispersion of graphene (B), the dispersant (C), and the nonionic surfactant (D).

7. A method for producing a graphene-containing thermoplastic resin composition according to claim 5 or 6, wherein the counterion in the aromatic sulfonate structure of compound (C) is a monovalent cation other than a hydrogen ion.

8. A method for producing a graphene-containing thermoplastic resin composition according to claim 5, wherein the nonionic surfactant (D) has a polyether structure.

9. A method for producing a molded article, comprising the step of melt-molding a graphene-containing thermoplastic resin composition obtained by the manufacturing method described in claim 5.

Images