Conductive composite material

Abstract

Provided is a conductive composite material of MXene and a polymer material that can balance high electrical conductivity and high strength. The conductive composite material is a conductive composite material that contains particles of a layered material having one or more layers, the layer including: a layer main body represented by the following formula: M m X n (n is 1 or more and 4 or less, and m is greater than n and 5 or less); a modification or a terminal T (T is at least one selected from the group consisting of a hydroxyl group, a fluorine atom, a chlorine atom, an oxygen atom, and a hydrogen atom) present on the surface of the layer main body, the polymer material having at least one selected from the group consisting of a fluorine atom, a chlorine atom, an oxygen atom, and a nitrogen atom as a hydrogen acceptor, and a hydroxyl group and / or a secondary amino group as a hydrogen donor, the proportion of the particles of the layered material being higher than 19 vol% and 95 vol% or less.

Description

Technical Field

[0001] This invention relates to conductive composite materials. Background Technology

[0002] In recent years, MXene has attracted attention as a novel conductive material. MXene is a type of so-called two-dimensional material, as described later, which is a layered material with one or more layers. Generally, MXene has the particle form of such layered materials (which can include powders, flakes, nanosheets, etc.).

[0003] To date, composite materials of the aforementioned MXene and polymers have been developed with the aim of improving strength and flexibility. For example, Non-Patent Literature 1 indicates that by making Ti3C2T, which is the aforementioned MXene, x Composite films with polyvinyl alcohol (PVA) can maintain conductivity while ensuring flexibility and mechanical strength. In Non-Patent Literature 2, a Ti3C2T MXene material with high flexibility and conductivity is disclosed as an MXene for achieving EMI shielding in thin films. x Composite films with sodium alginate (SA).

[0004] Non-patent document 3 discloses Ti3C2T as the aforementioned MXene, with the aim of ensuring conductivity and EMI shielding effect. x A maximum of 15% by mass of an EMI shielding nanocomposite material with epoxy resin. Non-Patent Literature 3 indicates that by annealing the aforementioned nanocomposite material, the Ti3C2T can be partially removed without generating byproducts. x The polar groups on the surface result in high electrical conductivity, excellent EMI shielding (SE) performance, and appropriate hardness.

[0005] In Non-Patent Document 4, as an electromagnetic (EM) absorption and shielding composite material, a material in which Ti3C2MXene exists in a wax matrix is ​​disclosed and subjected to annealing treatment is disclosed.

[0006] Non-Patent Document 5 discloses a composite material in which two-dimensional MXene is filled into polyurethane (PU) using an emulsion method. Furthermore, Non-Patent Document 5 discloses that by adding 0.5% by mass of MXene, the yield stress, tensile strength, and hardness of the polyurethane increase.

[0007] Non-Patent Document 6 discloses a composite material of ultrathin nanosheets of Ti3C2 (MXene) modified with hexadecyltrimethylammonium bromide (CTAB) and tris(tribromophenoxy)triazine (TBPC) and polyurethane as a flame retardant material using thermoplastic polyurethane (TPU).

[0008] Existing technical documents

[0009] Non-patent literature

[0010] Non-patent literature 1: Zheng Ling, et al., "Flexible and conductive MXene films and nanocomposites with high capacitance", Proceedings of the National Academy of Sciences, 2014, vol.11, pp.16676-16681

[0011] Non-patent literature 2: Faisal Shahzad, et al., “Electromagnetic interference shielding with 2D transition metal carbides (MXenes)”, Science, 2016, vol. 353, pp. 1137-1140

[0012] Non-patent document 3: Lei Wang, et al., "Fabrication on the annealed Ti3 C2TxMXene / Epoxy nanocomposites for electromagnetic interference shielding application", Composites Part B, 2019, vol.171, pp.111-118

[0013] Non-patent literature 4: Meikang Han, et al., "Ti3C2 MXenes with Modified Surface for High-Performance Electromagnetic Absorption and Shielding in the X-Band", ACSApplied Materials Interfaces, 2016, vol.8, pp.21011-21019 Non-patent literature 5: WeiqiangZhi, et al., "Study of MXene-filled polyurethane nanocomposites prepared via anemulsion method",Composites Science and Technology,2018,vol.168,pp.404-411

[0014] Non-patent document 6: Bin Yu, et al., "Interface decoration of exfoliated MXeneultra-thin nanosheets for fire and smoke suppressions of thermoplasticpolyurethane elastomer", Journal of Hazardous Materials, 2019, vol.374, pp.110-119 Summary of the Invention

[0015] The problem that the invention aims to solve

[0016] Among the MXene and polymer composites shown in Non-Patent Documents 1-6 above, the Ti3C2T in Non-Patent Document 1... x Composite films with PVA, although Ti3C2T x The content is as high as 90% by mass, but the conductivity is greatly reduced to that of pure Ti3C2T. x Less than one-tenth of the membrane.

[0017] The maximum 15% by mass of Ti3C2T shown in Non-Patent Document 3 xThe EMI shielding nanocomposite material with epoxy resin possesses suitable hardness that makes it difficult to deform under applied load. However, its maximum conductivity is 0.38 S / cm, which is significantly lower than the conductivity of pure MXene film, which is several thousand S / cm. Furthermore, the composite material in Non-Patent Document 4, which contains Ti3C2 (MXene) in a wax matrix, while exhibiting excellent electromagnetic (EM) absorption capabilities, still only has a conductivity of around 0.001 S / cm, significantly lower than that of pure MXene film.

[0018] The composite material of MXene and polyurethane in Non-Patent Literature 5 and Non-Patent Literature 6, although exhibiting high yield stress, tensile strength and hardness, is presumed to be insulating and is considered to have significantly low electrical conductivity.

[0019] On the other hand, the composite film of MXene and sodium alginate (SA) in Non-Patent Document 2 showed a maximum S / cm of 2963 (Ti3C2T). x The conductivity is 90% by mass, but the strength is considered low.

[0020] As mentioned above, current MXene-polymer composites cannot achieve both high electrical conductivity and high strength. In view of the above, the present invention aims to provide a composite material of MXene and polymer materials that achieves both high electrical conductivity and high strength.

[0021] Problem-solving methods

[0022] According to one aspect of the present invention, a conductive composite material comprising particles of a layered material having one or more layers and a polymeric material is provided, wherein...

[0023] The layer comprises: M m X n The layer body is represented by the formula (where M is at least one metal of group 3, 4, 5, 6, or 7, X is a carbon atom, a nitrogen atom, or a combination thereof, n is 1 or more and 4 or less, and m is greater than n and less than 5).

[0024] The modification or terminal T present on the surface of the main body of this layer (T is at least one selected from the group consisting of hydroxyl, fluorine, chlorine, oxygen and hydrogen atoms),

[0025] The polymer material, as a hydrogen acceptor, has at least one selected from the group consisting of fluorine, chlorine, oxygen, and nitrogen atoms, and as a hydrogen donor, has hydroxyl and / or secondary amino groups.

[0026] The proportion of particles in the layered material is higher than 19% by volume and lower than 95% by volume.

[0027] Invention Effects

[0028] According to the present invention, a conductive composite material is provided, comprising particles of a defined layered material (also referred to as "MXene" in this specification) and a polymer material, wherein the polymer material has at least one selected from the group consisting of fluorine atoms, chlorine atoms, oxygen atoms and nitrogen atoms as a hydrogen acceptor, and has hydroxyl and / or secondary amino groups as a hydrogen donor, wherein the proportion of the particles of the layered material is higher than 19% by volume and lower than 95% by volume, thereby providing a composite material comprising MXene and capable of achieving both high conductivity and high strength. Attached Figure Description

[0029] Figure 1 This is a schematic cross-sectional view illustrating a conductive composite material according to one embodiment of the present invention.

[0030] Figure 2 This is a schematic cross-sectional view of MXene, a layered material of a conductive composite material that can be used in one embodiment of the present invention.

[0031] Figure 3 This is a schematic diagram illustrating the presence or absence of hydrogen bonds in a conductive composite material according to one embodiment of the present invention and a prior art embodiment.

[0032] Figure 4 This is a graph showing the relationship between the MXene content and conductivity of various conductive composite materials.

[0033] Figure 5 This is a graph showing the relationship between the MXene content of each conductive composite material and its ratio to the conductivity of the MXene monomer. Detailed Implementation

[0034] Hereinafter, a conductive composite material according to one embodiment of the present invention will be described in detail, but the conductive composite material of the present invention is not limited to such an embodiment.

[0035] Reference Figure 1 The conductive composite material 20 of this embodiment comprises particles 10 of a defined layered material and a polymer material 11. The polymer material 11 has hydrogen acceptors and hydrogen donors, which are described later, thereby forming hydrogen bonds with the particles 10 of the layered material, increasing the affinity between the particles 10 of the layered material and the polymer material 11, and thus increasing the conductivity.

[0036] In this embodiment, the particles of the layered material are defined as MXene (particles), as follows.

[0037] A particle of a layered material containing one or more layers, wherein the layer is a layered material comprising the following (which can be understood as a layered compound, also denoted as "M"). m X n T x "x is any number; previously, z or s were sometimes used to replace x."

[0038] From the following formula: M m X n (where M is at least one Group 3, 4, 5, 6, or 7 metal, a so-called early transition metal, which may include, for example, at least one selected from the group consisting of Sc, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, and Mn; X is a carbon atom, a nitrogen atom, or a combination thereof; n is 1 or more and 4 or less; and m is greater than n and 5 or less) a layer body (which may have a lattice in which each X is located within an octahedral array of M); and a modification or terminator T (T is at least one selected from the group consisting of hydroxyl, fluorine, chlorine, oxygen, and hydrogen atoms) present on the surface of the layer body (more specifically, at least one of the two opposing surfaces of the layer body). Typically, n is 1, 2, 3, or 4.

[0039] In the above formula of MXene, M is preferably selected from at least one of the group consisting of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo and Mn, and more preferably from at least one of the group consisting of Ti, V, Cr and Mo.

[0040] In the above formula for MXene, it is further preferred that M is Ti and X is a carbon atom, or a combination of carbon and nitrogen atoms. As the main body of the MXene layer, it is even more preferred that at least one is selected from the group consisting of Ti3C2, Ti3CN, and Ti2C. Particularly preferred is Ti3C2T. x (x is any number).

[0041] Such MXenes can be synthesized by selectively etching (removing and, depending on the case, separating the layers) A atoms (and, depending on the case, a portion of the M atoms) from the MAX phase.

[0042] The MAX phase is given by the following formula: M m AX n The expression (where M, X, n, and m are as described above, and A is at least one element from Group 12, 13, 14, 15, or 16, typically a Group A element, representatively Group IIIA and Group IVA, and more specifically, includes at least one element selected from the group consisting of Al, Ga, In, Tl, Si, Ge, Sn, Pb, P, As, S, and Cd, preferably Al), and the layer having A atoms is located in the group consisting of M... m Xn This represents a crystal structure between two layers (each X can have a lattice located within an octahedral array of M). The MAX phase, typically in the case of m = n+1, has the following repeating unit: between each of the n+1 M atomic layers, one X atomic layer is arranged (these are collectively referred to as "M"). m X n The A atomic layer (“A atomic layer”) is configured as the next layer after the (n+1)th M atomic layer, but is not limited to this.

[0043] During the fabrication of MXene, the A atoms (and, depending on the case, a portion of the M atoms) of the MAX phase are selectively etched (removed and, depending on the case, separated into layers). This removes the A atom layer (and, depending on the case, a portion of the M atoms), as well as hydroxyl, fluorine, chlorine, oxygen, and hydrogen atoms present in the etching solution (typically, an aqueous solution containing hydrofluoric acid is used, but not limited to this), thus exposing the M atoms. m X n The surface of the layer is modified to create an end surface. Etching can be performed using F-containing materials. － The etching process can be carried out using a solution such as a mixture of lithium fluoride and hydrochloric acid, or a solution using hydrofluoric acid. Subsequently, layer separation (separation, separating multi-layered MXene into monolayered MXene) can be promoted by any appropriate post-treatment (e.g., ultrasonic treatment or hand shaking). For example, when obtaining monolayered or few-layered MXene as described below, the following method is preferred: After rinsing the etched material obtained by the above etching with water, intercalation can be performed. As the intercalation compound, alkali metal compounds, alkaline earth metal compounds, and Li-containing compounds are preferred. The specific intercalation method is not particularly limited; for example, the intercalation compound can be mixed with the water-soluble clay obtained after water rinsing, and the mixture can be stirred or left to stand. Next, a separation process is performed, including stirring the material obtained by the above intercalation in a liquid such as water. When obtaining monolayered or few-layered MXene, ultrasonic treatment is preferably not performed as a separation process. After layering, the particles are washed with water, and the resulting layered material particles can be obtained as monolayer or few-layer MXene.

[0044] MXene, known to be derived from the above formula: M m X n Express it like this.

[0045] Sc2C, Ti2C, Ti2N, Zr2C, Zr2N, Hf2C, Hf2N, V2C, V2N, Nb2C, Ta2C, Cr2C, Cr2N, Mo2C, Mo 1.3 C, Cr 1.3C, (Ti,V)2C, (Ti,Nb)2C, W2C, W 1.3 C, Mo2N, Nb 1.3 C, Mo 1.3 Y 0.6 C (In the above formula, "1.3" and "0.6" mean approximately 1.3 (=4 / 3) and approximately 0.6 (=2 / 3), respectively.)

[0046] Ti3C2, Ti3N2, Ti3(CN), Zr3C2, (Ti, V)3C2, (Ti2Nb)C2, (Ti2Ta)C2, (Ti2Mn)C2, Hf3C2, (Hf2V)C2, (Hf2Mn)C2, (V2Ti)C2, (Cr2Ti)C2, (Cr2V)C 2. (Cr2Nb)C2, (Cr2Ta)C2, (Mo2Sc)C2, (Mo2Ti)C2, (Mo2Zr)C2, (Mo2Hf)C2, (Mo2V)C2, (Mo2Nb)C2, (Mo2Ta)C2, (W2Ti)C2, (W2Zr)C2, (W2Hf)C2,

[0047] Ti4N3, V4C3, Nb4C3, Ta4C3, (Ti,Nb)4C3, (Nb,Zr)4C3, (Ti2Nb2)C3, (Ti2Ta2)C3, (V2Ti2)C3, (V2Nb2)C3, (V2Ta2)C3, (Nb2Ta2)C3, (Cr2Ti2)C3, (Cr2V 2)C3, (Cr2Nb2)C3, (Cr2Ta2)C3, (Mo2Ti2)C3, (Mo2Zr2)C3, (Mo2Hf2)C3, (Mo2V2)C3, (Mo2Nb2)C3, (Mo2Ta2)C3, (W2Ti2)C3, (W2Zr2)C3, (W2Hf2)C3, (Mo 2.7 V 1.3 In the above formula, "2.7" and "1.3" mean approximately 2.7 (=8 / 3) and approximately 1.3 (=4 / 3), respectively.

[0048] Representatively, in the above formula, M can be titanium or vanadium, and X can be a carbon atom or a nitrogen atom. For example, the MAX phase is Ti3AlC2, and MXene is Ti3C2T. x (In other words, M is Ti, X is C, n is 2, and m is 3).

[0049] Furthermore, in this invention, MXene may contain a relatively small amount of residual A atoms, for example, less than 10% by mass relative to the original A atoms. The residual amount of A atoms is preferably less than 8% by mass, more preferably less than 6% by mass. However, even if the residual amount of A atoms exceeds 10% by mass, it may not be a problem depending on the application and conditions of use of the paste (and the conductive film obtained therefrom).

[0050] The synthesized MXene (particles) 10, as shown in the example Figure 2 The illustration is schematic and can be a layered material containing one or more MXene layers 7a, 7b (as an example of MXene (particles) 10, in...). Figure 2 (a) shows one layer of MXene10a. Figure 2 (b) shows two layers of MXene10b, but is not limited to these examples). More specifically, MXene layers 7a and 7b have: [The text abruptly ends here, so the translation stops as well.] m X n The layer body (M) is represented m X n Layers 1a and 1b; modifications or ends T3a, 5a, 3b, and 5b existing on the surfaces of the layers 1a and 1b (more specifically, at least one of the two opposing surfaces of each layer). Therefore, MXene layers 7a and 7b are also represented as "M". m X n T x "x is any number. MXene10 can be such that MXene layers are separated and exist as a single layer." Figure 2 The single-layer structure shown in (a), the so-called single-layer MXene 10a), can also be a stack of multiple MXene layers separated from each other. Figure 2(b) shows a multilayer structure, the so-called multilayer MXene 10b, which may also be a mixture thereof. MXene 10 may be particles (also called powder or flakes) that are aggregates composed of a single layer of MXene 10a and / or multiple layers of MXene 10b. In this embodiment, MXene 10 is preferably composed mostly of particles (also called nanosheets) of a single layer of MXene 10a. In the case of multilayer MXene, two adjacent MXene layers (e.g., 7a and 7b) are not necessarily completely separated, but may be in partial contact. When including the above-mentioned multilayer MXene, it is preferable that the multilayer MXene is also a low-layer MXene obtained by interlayer peeling treatment. The term "low-layer" means, for example, that the number of MXene layers is 10 or less. Hereinafter, this "low-layer multilayer MXene" is sometimes referred to as "low-layer MXene". The thickness of the low-layer MXene in the stacking direction is preferably 10 nm or less. In addition, in this specification, single-layer MXene and low-layer MXene are referred to together as "single-layer / low-layer MXene".

[0051] While not limited to this embodiment, the thickness of each MXene layer (equivalent to MXene layers 7a and 7b described above) is, for example, 0.8 nm or more and 5 nm or less, particularly 0.8 nm or more and 3 nm or less (depending mainly on the number of M-atom layers contained in each layer), and the maximum dimension in a plane parallel to the layer (two-dimensional unfolded plane) is, for example, 0.1 μm or more and 200 μm or less, particularly 1 μm or more and 40 μm or less. When the MXene is a stack (multilayer MXene), the interlayer distance (or void size) is, for each stack, Figure 2 (b) denoted by Δd), for example, is 0.8 nm or more and 10 nm or less, particularly preferably 0.8 nm or more and 5 nm or less, more preferably about 1 nm, the total number of layers is 2 or more, but for example, 50 or more and 100,000 or less, particularly 1,000 or more and 20,000 or less, the thickness in the stacking direction is for example, 0.1 μm or more and 200 μm or less, particularly 1 μm or more and 40 μm or less, the maximum dimension in the plane (two-dimensional unfolded surface) perpendicular to the stacking direction is for example, 0.1 μm or more and 100 μm or less, particularly 1 μm or more and 20 μm or less. Furthermore, these dimensions can be obtained as digital average dimensions (e.g., at least 40 digital averages) based on scanning electron microscope (SEM), transmission electron microscope (TEM) images or atomic force microscope (AFM) images, or as distances in real space calculated from the positions of the (002) planes in the reciprocal lattice space measured by X-ray diffraction (XRD).

[0052] In this embodiment, the polymer material mixed with the particles of the layered material has at least one selected from the group consisting of fluorine atoms, chlorine atoms, oxygen atoms and nitrogen atoms as a hydrogen acceptor, and has hydroxyl and / or secondary amino groups as a hydrogen donor.

[0053] In this embodiment, using Figure 3 (a) to (c) are schematic diagrams illustrating the presence or absence of hydrogen bonds within conductive composite materials. Figure 3 In (a) to (c), as MXene, Ti3C2T x Let's take an example to illustrate. Previously, such as... Figure 3 (a) Due to the presence of the polymer material, a rebound force is generated between the MXene and the polymer material, increasing the interfacial distance between the MXenes. This can be understood as a decrease in conductivity due to the presence of the polymer material. In contrast, according to this embodiment, as described above, since the polymer material has both a hydrogen acceptor and a hydrogen donor, such as... Figure 3 (b) and Figure 3 (c) As illustrated, hydrogen bonds are formed between the MXene surface and the polymer material. Figure 3 (b) and Figure 3 (c) indicated by dashed lines), especially as Figure 3 (c) Because the polymer material has both hydrogen acceptors and hydrogen donors, more hydrogen bonds can be formed between the MXene surface and the polymer material than before. As a result, it is believed that the interfacial distance between MXenes can be further reduced, leading to increased film strength and high conductivity. More specifically, since MXenes must have at least one terminal element selected from the group consisting of hydroxyl, fluorine, chlorine, oxygen, and hydrogen atoms, and the polymer material has at least one hydrogen acceptor selected from the group consisting of fluorine, chlorine, oxygen, and nitrogen atoms, and has hydroxyl and / or secondary amino groups as hydrogen donors, the interfacial distance between MXenes can be shortened by utilizing the hydrogen bonds between the MXenes and the polymer material, thereby increasing film strength and achieving high conductivity. In addition to the aforementioned hydrogen bonds, the Ti-N and C-N bonds formed between MXenes and the polymer material are also believed to contribute to the improved affinity between MXenes and the polymer material.

[0054] The polymer material preferably comprises: a polymer having a carbamate bond, and one or more polymers having a unit derived from a (meth)acryloyl group, or...

[0055] Combination of one or more of these polymers with one or more additives having hydroxyl and secondary amino groups.

[0056] Examples of polymers constituting the aforementioned polymer materials include polyimides (PI) containing secondary amino groups, such as polyethyleneimine (PEI), polypyrrole (PPy), polyaniline (PANI), and flame-retardant polyimide. Examples of polymers containing urethane bonds (-NHCO-) ​​include polyamide-imide (PAI), polyacrylamide (PMA), nylon (polyamide resin), DNA (deoxyribonucleic acid), acetanilide, and acetaminophen.

[0057] Among them, the polymer constituting the above-mentioned polymer material is preferably one or more of a polymer having a urethane bond and a polymer having a unit derived from a (meth)acryloyl group. The polymers having urethane bonds and the polymers having units derived from (meth)acryloyl groups have high affinity for MXene, enabling the formation of a smooth film and contributing to improved conductivity. As a result, both high conductivity and high strength can be achieved. The above-mentioned polymer material is preferably composed of one or more of a polymer having a urethane bond and a polymer having a unit derived from a (meth)acryloyl group, and more preferably composed of a polymer having a urethane bond.

[0058] The polymer having urethane bonds is more preferably polyurethane, and even more preferably one or more of polyether-based polyurethane, polycarbonate-based polyurethane, and polyester-based polyurethane. Polyether-based polyurethane means polyurethane containing structural units derived from polyester; polycarbonate-based polyurethane means polyurethane containing structural units derived from polycarbonate; and polyester-based polyurethane means polyurethane containing structural units derived from polyester. The polymer material is more preferably composed of one or more of polyether-based polyurethane, polycarbonate-based polyurethane, and polyester-based polyurethane.

[0059] Polymers having units derived from (meth)acryloyl groups, i.e., acrylic resins, are polymers having one or more structural units derived from acrylic acid and methacrylic acid. Anionic acrylic resins are more preferred as said acrylic resins. Anionic acrylic resins having one or more alkoxymethylamide groups and hydroxyl groups are even more preferred.

[0060] As another embodiment, the polymer material described above may also include a combination of the polymer and an additive having one or more of a hydroxyl and a secondary amino group. Examples of additives having one or more of a hydroxyl and a secondary amino group include surfactants having one or more of a hydroxyl and a secondary amino group. Examples of such surfactants include tetraethylene glycol. When the polymer material contains the additives described above, the additives, in addition to the polymer, may also act as hydrogen donors. For example, examples of polymer materials include a combination of a polymer having a unit derived from (meth)acryloyl groups and a surfactant such as tetraethylene glycol.

[0061] The proportion of the layered material particles is higher than 19% by volume and lower than 95% by volume. By ensuring that the proportion of the layered material particles is higher than 19% by volume, conductivity can be ensured. From the viewpoint of further improving conductivity, the proportion of the layered material particles is more preferably 30% by volume or higher, more preferably 35% by volume or higher, and even more preferably 50% by volume or higher. On the other hand, from the viewpoint of ensuring the film strength of the MXene particle / polymer composite material, it is preferable that the proportion of the layered material particles is 95% by volume or lower, more preferably 75% by volume or lower, and even more preferably 50% by volume or lower. The above-mentioned proportion of the layered material particles refers to the proportion contained in the conductive composite material. The conductive composite material of the present invention sometimes also contains additives such as colorants and antioxidants; in this case, the above-mentioned proportion of the layered material particles refers to the proportion contained in the conductive composite material containing the aforementioned additives.

[0062] The conductive composite material of this embodiment has no particular shape. For example, in addition to a planar (sheet) shape, it can also be a cuboid, sphere, polyhedron, or other shape with thickness, a paste, slurry, etc. The conductive composite material of this embodiment can also be a coating film formed on the surface of a substrate. When the conductive composite material of this embodiment is a coating film, it is not limited to a planar (sheet) shape, and can be shaped such as adhering to at least a portion of the surface of the object to be coated or covering the object to be coated. As a preferred shape of the conductive composite material, a planar (sheet) shape can be mentioned. In the case of a planar (sheet) shape, it can have two main surfaces that are opposite each other. The thickness, shape and size when viewed from above, etc. of the sheet-shaped conductive composite material can be appropriately selected according to the application of the conductive composite material. The conductive composite material of this embodiment can also be, for example, a paste or slurry such as a conductive paste. As such a paste or slurry, for example, it can be a mixture of particles of a defined layered material and a polymer material, and, as needed, a mixture of aqueous medium, organic medium, metal particles, ceramic particles, etc. The mass proportion of the layered material particles in the paste or slurry can be, for example, 20% or more, and further, 50% or more. As an example of its use, the paste or slurry can be applied to a substrate and dried to form a conductive film.

[0063] When the conductive composite material of this embodiment is formed on the surface of a substrate, the shape and material of the substrate are irrelevant. The shape of the substrate can be, for example, plate-like, spherical, needle-like, or uneven. The material of the substrate can include metallic materials, ceramic materials, polymeric materials containing conductive polymers, or composite materials containing two or more of these. For example, examples of metallic materials include gold, silver, copper, platinum, nickel, titanium, tin, iron, zinc, magnesium, aluminum, tungsten, molybdenum, or alloys containing 50% by mass or more of these metals.

[0064] When the conductive composite material is in the form of a sheet, its thickness can be measured, for example, by cross-sectional observation using a micrometer, a stylus surface shape measuring instrument, a scanning electron microscope (SEM), a microscope, a laser microscope, or other methods.

[0065] The method for manufacturing the conductive composite material of this embodiment using MXene generated as described above is not particularly limited. When the conductive composite material of this embodiment has a plate-like shape, for example as illustrated below, the layered material and the polymer material can be mixed to form a coating film.

[0066] First, the MXene aqueous dispersion, MXene organic solvent dispersion, or MXene powder containing the aforementioned MXene particles (particles of the layered material) in the solvent is mixed with the polymer material. The solvent for the aforementioned MXene aqueous dispersion is typically water; however, depending on the circumstances, other liquid substances may be included in small amounts (e.g., 30% by mass or less, preferably 20% by mass or less, on a total basis).

[0067] The mixing of the MXene particles with the polymer material can be carried out using dispersion devices such as homogenizers, paddle mixers, thin-film gyratory mixers, planetary mixers, mechanical oscillators, and vortex mixers.

[0068] The slurry, which is a mixture of the aforementioned MXene particles and polymer materials, can be applied to a substrate or similar object. The application method is not limited. Examples include spray coating using nozzles such as single-fluid nozzles, two-fluid nozzles, or spray guns; slot coating using a benchtop coater, comma blade coater, or doctor blade coater; screen printing; metal mask printing; and coating methods such as spin coating or drip coating. Depending on the application, the aforementioned object can be a printed circuit board, a metal substrate, a resin substrate, a laminated electronic component, a metal pin, or a metal wire.

[0069] The coating and drying process described above can be repeated as needed until a film of the desired thickness is obtained. For example, drying and curing can be performed at temperatures below 400 degrees Celsius using an atmospheric pressure oven or a vacuum oven.

[0070] The conductive composite material of this embodiment, as shown in the examples described later, preferably maintains a conductivity of 280 S / cm or higher when it is, for example, a sheet with a film thickness of 5 μm. The conductivity is preferably maintained at 1000 S / cm or higher, more preferably 2000 S / cm or higher, even more preferably 3000 S / cm or higher, and still more preferably 6000 S / cm or higher. There is no particular upper limit to the conductivity of the conductive film; for example, it can be 25000 S / cm or lower. The conductivity can be measured using a resistivity meter.

[0071] The conductive composite material of this embodiment, as described above, has high conductivity and exhibits high strength, and therefore can be used for any suitable application. For example, it can be used in any suitable electrical device as electrodes, electromagnetic shielding (EMI shielding), or other applications requiring the maintenance of high conductivity (reducing the decrease in initial conductivity and preventing oxidation).

[0072] The conductive composite material according to one embodiment of the present invention has been described in detail above, but various modifications can be made. It should also be noted that the conductive composite material of the present invention can also be manufactured by methods different from those described in the above embodiment.

[0073] Example

[0074] [Example 1]

[0075] Preparation of MAX particles (precursors to MXene particles)

[0076] TiC powder, Ti powder, and Al powder (all manufactured by High Purity Chemical Research Institute, Ltd.) were mixed in a 2:1:1 molar ratio in a ball mill containing zirconia balls for 24 hours. The resulting mixture was calcined at 1350°C for 2 hours under an Ar atmosphere. The resulting calcined body (green body) was then pulverized with an end mill to a maximum size of less than 40 μm. This yielded Ti3AlC2 particles as the MAX particles.

[0077] • Precursor etching and Li intercalation

[0078] Using Ti3AlC2 particles (powder) prepared by the above method, etching and Li intercalation were performed under the following etching conditions to obtain a solid-liquid mixture (slurry) containing solid components from Ti3AlC2 powder.

[0079] (Etching of the precursor and conditions for Li intercalation)

[0080] • Precursor: Ti3AlC2 (passed through a sieve with a mesh size of 45μm)

[0081] • Etching solution composition: LiF 3g

[0082] 30 mL of 9M HCl

[0083] • Precursor dosage: 3g

[0084] • Etched container: 100mL bottle

[0085] • Etching temperature: 35℃

[0086] Etching time: 24 hours

[0087] • Mixer speed: 400 rpm

[0088] Cleaning after etching

[0089] The above slurry was divided into two portions and inserted into two 50 mL centrifuge tubes. The tubes were centrifuged at 3500 G, and the supernatant was discarded. For the remaining precipitate in each centrifuge tube, (i) 40 mL of pure water was added, (ii) the tubes were centrifuged again at 3500 G, and (iii) the supernatant was removed. This process (i) to (iii) was repeated a total of 10 times. The supernatant was discarded after confirming that the pH of the supernatant from the 10th run was above 5, yielding Ti3C2T. x - Moisture-rich clay medium.

[0090] Layering

[0091] Regarding the aforementioned Ti3C2T x - For the water-medium clay, (i) 40 mL of pure water was added and the mixture was stirred for 15 minutes, (ii) centrifuged at 3500 G, and (iii) the supernatant was recovered as a monolayer MXene-containing solution. This process (i) to (iii) was repeated a total of 4 times to obtain a monolayer MXene-containing supernatant. Furthermore, this supernatant was centrifuged again at 4300 G for 2 hours using a centrifuge, and the supernatant was discarded, yielding monolayer / minimum layer MXene-containing clay as a sample.

[0092] Formation of MXene / polyurethane composite membranes

[0093] The above-mentioned clay containing monolayer and few-layer MXene, pure water, and polyurethane (manufactured by Daihatsu Seika Co., Ltd., RESAMONED-4080 (polyether / carbonate)) were mixed and manually stirred for 5 minutes to obtain an MXene / polyurethane composite liquid, thereby obtaining MXene (Ti3C2T) in the MXene / polyurethane composite membrane. x The proportions (after film drying) of MXene / polyurethane composite films were 25, 50, 75, and 100% by volume, respectively.

[0094] The obtained MXene / polyurethane composite liquid was sprayed onto a PET substrate ("LUMIRROR" (registered trademark) manufactured by Toray Industries, Inc., 15 cm square). The coating was subjected to 15 cycles of spraying and drying in a dryer until the MXene / polyurethane composite film thickness reached 5 μm. After coating, the film was dried in an oven at 80°C for approximately 30 minutes to obtain the MXene / polyurethane composite film.

[0095] [Example 2]

[0096] Preparation of MAX particles (precursors to MXene particles)

[0097] MAX particles were obtained in the same manner as in Example 1.

[0098] • Etching of precursor

[0099] Using Ti3AlC2 particles (powder) prepared by the above method, etching was performed under the following etching conditions to obtain a solid-liquid mixture (slurry) containing solid components from the Ti3AlC2 powder.

[0100] (Etching conditions)

[0101] • Precursor: Ti3AlC2 (passed through a 45μm sieve)

[0102] • Etching solution composition: 49% HF 6mL

[0103] 18mL H2O

[0104] 36 mL of HCl (12M)

[0105] • Precursor dosage: 3.0g

[0106] • Etched container: 100mL bottle

[0107] • Etching temperature: 35℃

[0108] Etching time: 24 hours

[0109] • Mixer speed: 400 rpm

[0110] Cleaning after etching

[0111] The above slurry was divided into two portions and inserted into two 50 mL centrifuge tubes respectively. The tubes were centrifuged at 3500 G, and the supernatant was discarded. For the remaining precipitate in each centrifuge tube, 40 mL of pure water was added, and the tubes were centrifuged again at 3500 G to remove the supernatant. This process was repeated 11 times. After the final centrifugation, the supernatant was discarded, yielding Ti3C2T. x - Moisture-rich clay medium.

[0112] Li intercalation

[0113] For Ti3C2T prepared by the above method x - Li intercalation was performed on a water-medium clay using LiCl as a Li-containing compound under the following conditions, with stirring at 20°C or above and 25°C or below for 12 hours.

[0114] (Conditions for Li intercalation)

[0115] ·Ti3C2T x - Moisture-modified clay (MXene after washing): Solid content 0.75g

[0116] • LiCl: 0.75g

[0117] • Intercalation container: 100mL bottle

[0118] Temperature: Above 20℃ and below 25℃ (room temperature)

[0119] • Time: 10 hours

[0120] • Mixer speed: 800 rpm

[0121] Layering

[0122] Regarding the aforementioned Ti3C2T x - Moisture-medium clay: (i) 40 mL of pure water was added and the mixture was stirred for 15 minutes; (ii) it was centrifuged at 3500 G; (iii) the supernatant was recovered as a monolayer MXene-containing solution. Steps (i) to (iii) were repeated a total of 4 times to obtain a supernatant containing monolayer MXene. This supernatant was then centrifuged again at 4300 G for 2 hours using a centrifuge. The supernatant was discarded, and the resulting clay was used as a monolayer / minor layer MXene-containing sample.

[0123] Formation of MXene / acrylic composite membrane

[0124] The above-mentioned clay containing monolayer and few-layer MXene, pure water, and acrylic resin (manufactured by Toa Synthetic Co., Ltd., NW-400, hereinafter referred to as "acrylic acid") were mixed and stirred for 15 minutes using a mixer (manufactured by FAST & Fluid Co., Ltd., SK550 1.1) to obtain an MXene / acrylic acid composite liquid, thereby obtaining MXene (Ti3C2T) in the MXene / acrylic acid composite membrane. x The proportions (after film drying) of MXene / acrylic composite films were 25% and 83% by volume, respectively.

[0125] The obtained MXene / acrylic composite liquid was sprayed onto a PI substrate (manufactured by ASONE Corporation, 3 cm square). The above spray coating and drying in a dryer were repeated 30 times to form a coating film before drying. After coating, it was dried in an atmospheric pressure oven at 80°C for 2 hours, and then dried in a vacuum oven at 150°C for about 15 hours to obtain an MXene / acrylic composite film.

[0126] [Comparative Example 1]

[0127] Sodium alginate (SA) was used as a polymer material to obtain MXene (Ti3C2T) in the MXene / sodium alginate (SA) composite film. xThe proportions (after film drying) of MXene / SA composite films were 3, 12, 24, 32, 55, 73, and 100% by volume, respectively. Except for these, the MXene / SA composite films were obtained in the same manner as in Example 1 above.

[0128] [Comparative Example 2]

[0129] Polyvinyl alcohol (PVA) was used as a polymer material to obtain MXene / PVA composite films containing MXene (Ti3C2T). x The proportions (after film drying) of MXene / PVA composite films were 1, 13, 26, 48, 67, and 100% by volume, respectively. Otherwise, the MXene / PVA composite films were obtained in the same manner as in Example 1 above.

[0130] [Measurement of electrical conductivity of composite membranes]

[0131] The electrical conductivity of the obtained MXene / polyurethane composite film, MXene / acrylic composite film, MXene / SA composite film, and MXene / PVA composite film was determined. The conductivity was calculated by measuring the resistivity (Ω) and thickness (μm) at three locations for a single sample, and then calculating the conductivity (S / cm) from these measurements. The arithmetic mean of the three conductivity values ​​was then used. A low resistivity meter (Loresta AX MCP-T370, manufactured by Mitsubishi Chemical Analysis Co., Ltd.) was used for resistivity measurements. A micrometer (MDH-25MB, manufactured by Mitutoyo Co., Ltd.) was used for thickness measurements. The results are shown in... Figure 4 In. Figure 4 In this process, due to different MXene fabrication methods, the presence and content of impurities in the resulting composite films lead to variations in the conductivity of the MXene monomer films. Therefore, the conductivity of the MXene monomer films is also calculated. Figure 4 The results show that when the MXene content of each composite membrane is 100% by volume (i.e., the polymer material is 0% by volume), the conductivity ratio of each MXene content is calculated to be 100%. Figure 5 In. Figure 4 and Figure 5 In this context, MXene content represents the proportion (by volume) of MXene in the composite film after film formation and drying.

[0132] In the case of MXene / polyurethane composite membranes, such as Figure 4 As shown, MXene(Ti3C2T) x When the proportion of ) is 75% by volume, a conductivity of approximately 4600 S / cm can be obtained. This conductivity is as follows: Figure 5 As shown, this is equivalent to pure MXene (i.e., Ti3C2T).x The conductivity is 68% (100% by volume). Additionally, as... Figure 5 As shown, even MXene(Ti3C2T) x Even when the proportion is a small amount (25% by volume), it is still possible to ensure pure MXene (i.e., Ti3C2T). x The conductivity is 15% (100% by volume). Furthermore, although... Figure 4 Not shown in the text, but MXene(Ti3C2T) x When the proportion of ) is 19% by volume, a conductivity of approximately 280 S / cm can be achieved.

[0133] In the case of MXene / acrylic composite membranes, such as Figure 4 As shown, MXene(Ti3C2T) x When the proportion of α is 83% by volume, a conductivity of approximately 15000 S / cm can be obtained. This conductivity is as follows: Figure 5 As shown, this is equivalent to pure MXene (i.e., Ti3C2T). x The conductivity is 79% (100% by volume). Additionally, as... Figure 5 As shown, even MXene(Ti3C2T) x Even when the proportion is a small amount (25% by volume), it is still possible to ensure pure MXene (i.e., Ti3C2T). x The conductivity is 18% (100% by volume).

[0134] On the other hand, in the case of MXene / PVA composite membranes, such as Figure 4 and Figure 5 As shown, even MXene(Ti3C2T) x When the proportion of MXene reaches a certain level of 67% by volume, the conductivity also drops to as low as 220 S / cm, decreasing to that of pure MXene (i.e., Ti3C2T). x The conductivity is less than 10% of 100% by volume.

[0135] In contrast, the MXene / PVA composite membrane exhibits significantly lower electrical conductivity. On the other hand, the MXene / SA composite membrane maintains conductivity, but as shown in Table 2 below, the membrane exhibits low strength, and cohesive failure is confirmed regardless of the SA content.

[0136] [Strength Evaluation of Composite Membranes]

[0137] After conducting the aforementioned conductivity measurements on the MXene / polyurethane composite film, MXene / acrylic composite film, and MXene / SA composite film, a tape peel test was performed on each as follows. Specifically, adhesive tape (3M, SCOTCH 600 TAPE, 1 / 2 inch wide) was applied to a portion of the upper surface of the composite film formed on the PET substrate, then peeled off. The composite film was then visually inspected for any cohesive damage, i.e., whether intra-film separation occurred due to a portion of the composite film transferring to the tape adhesion surface. The evaluation results for cases using polyurethane, acrylic, and SA as polymer materials are shown in Tables 1, 2, and 3.

[0138] Table 1

[0139]

[0140] Table 2

[0141]

[0142] Table 3

[0143]

[0144] The results in Tables 1, 2, and 3 confirm that in the MXene monomer film, the torn tape adhered to both the film and the substrate, indicating cohesive failure (internal destruction of the film). Furthermore, when SA was used as a polymer material, cohesive failure occurred in the same manner as with the MXene monomer film, regardless of the MXene content. On the other hand, no cohesive failure occurred in the samples mixed with polyurethane or acrylic acid as polymer materials.

[0145] Based on the above measurements of the electrical conductivity and strength of the composite membrane, in this embodiment, by adding a specified amount of MXene particles to the composite material of MXene particles and polymer materials, both conductivity and high strength can be ensured. In particular, it can be inferred that by increasing the proportion of the layered material (MXene) to over 19% by volume, a conductivity of approximately 280 S / cm or higher can be achieved. Specifically, the conductivity of the composite material containing 75% by volume of MXene and polyurethane can be 68% of that of a pure MXene membrane. Furthermore, the conductivity of the composite material containing 83% by volume of MXene and acrylic acid can be 79% of that of a pure MXene membrane. As mentioned above, the reason for achieving both high conductivity and high strength is that the hydrogen bonds between MXene and the polymer material reduce the interfacial spacing, maintaining a state where electricity can flow easily. Also, it can be considered that the acrylic acid used as a raw material in the examples has carboxyl (hydroxyl) groups, and even after synthesis, some carboxyl groups remain, meaning that acrylic acid has a certain number of hydroxyl groups.

[0146] Industrial availability

[0147] The conductive composite material of the present invention can be used for any suitable purpose, and is preferably used as, for example, electrodes and electromagnetic shielding of electrical devices.

[0148] This application is accompanied by a priority claim based on Japanese Patent Application No. 2020-131866, which is incorporated herein by reference.

[0149] Symbol Explanation

[0150] 1a and 1b main body (M) m X n layer)

[0151] 3a, 5a, 3b, 5b Modifications or terminal T

[0152] 7a, 7b MXene layers

[0153] 10, 10a, 10b MXene particles (particles in layered materials)

[0154] 11 Polymer Materials

[0155] 20 Conductive composite materials

Claims

1. A conductive composite material comprising particles of a layered material having one or more layers and a polymer material, wherein, The layer includes: From the following formula: M m X n The main body of the layer is represented. In the formula, M is at least one metal from Groups 3, 4, 5, 6, or 7. X is a carbon atom, a nitrogen atom, or a combination of carbon and nitrogen atoms. n is 1 or more and 4 or less m is greater than n and less than 5; Modifications or end points T present on the surface of the main body of this layer, Wherein, T is selected from at least one of the group consisting of hydroxyl, fluorine, chlorine, oxygen and hydrogen atoms. The polymer material has: at least one selected from the group consisting of fluorine, chlorine, oxygen, and nitrogen atoms as a hydrogen acceptor; and hydroxyl and / or secondary amino groups as hydrogen donors. The proportion of particles in the layered material is higher than 19% by volume and lower than 95% by volume. The number of layers stacked is 10 or less, and the thickness in the stacking direction is 10 nm or less. The conductivity of the conductive composite material is above 280 S / cm.

2. The conductive composite material according to claim 1, wherein, The modification or terminal T has: at least one selected from the group consisting of fluorine, chlorine, and oxygen atoms as a hydrogen acceptor; and a hydroxyl group and / or a hydrogen atom as a hydrogen donor.

3. The conductive composite material according to claim 1 or 2, wherein, The polymer material has the following characteristics: Polymers having urethane bonds, and polymers having one or more units derived from (meth)acryloyl groups; or Combination of one or more of these polymers with one or more additives having hydroxyl and secondary amino groups.

4. The conductive composite material according to claim 1 or 2, wherein, The M is selected from at least one of the group consisting of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo and Mn.

5. The conductive composite material according to claim 1 or 2, wherein, The main body of the layer contains at least one selected from the group consisting of Ti3C2, Ti3CN and Ti2C.

6. The conductive composite material according to claim 1 or 2, wherein, The polymer material is one or more of polyether polyurethane, polycarbonate polyurethane, and polyester polyurethane.

7. The conductive composite material according to claim 1 or 2, having a coating morphology.

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