Graphene complex, dispersion containing graphene complex, composition and formed product

Abstract

To provide a graphene composite, a graphene composite dispersion, a composition, and a formed product that can yield a graphene-containing product with superior dispersibility and corrosion resistance. [Solution] A graphene composite comprising graphene particles and a metal phosphate or phosphate, wherein the metal phosphate or phosphate is present on the surface of the graphene particles; and a dispersion, composition, and product containing the graphene composite.

Description

Technical Field

[0001] The present invention relates to a graphene composite, a dispersion liquid, a composition, and a formed product containing the graphene composite.

Background Art

[0002] Graphene is a two-dimensional sheet-like material composed of carbon atoms. The thin layer sheet structure of graphene has functions such as barrier properties, thermal conductivity, and electrical conductivity. For example, by utilizing the barrier property of graphene, the permeation of oxygen and water, which are causative substances of metal corrosion, can be suppressed. As an example of an application that utilizes such functions of graphene, a corrosion-resistant paint is mentioned, and further improvement in corrosion resistance is expected by using graphene (see, for example, Patent Document 1).

[0003] As a paint that requires particularly high corrosion resistance, a rust-preventive paint that utilizes the sacrificial anti-corrosion effect of zinc particles is used. Graphene has not only barrier properties but also electrical conductivity. By adding graphene to such a rust-preventive paint, the sacrificial anti-corrosion effect of zinc particles can be further enhanced, and the long-term rust-preventive performance is improved. In addition, since the rust-preventive performance is improved by the addition of graphene, it is also possible to reduce the required amount of zinc particles. (See, for example, Patent Document 2) On the other hand, in order to industrially utilize graphene, a dispersion liquid of graphene having excellent electrical conductivity, coating property, and dispersibility is used. As a dispersion liquid of graphene, for example, a dispersion liquid in which graphene is dispersed in a solvent containing 50% by mass or more of N-methylpyrrolidone, and the weight absorption coefficient at a wavelength of 270 nm of a diluted solution adjusted to a graphene weight fraction of 0.000013 with N-methylpyrrolidone is 25000 cm -1 above 200000 cm -1 or less is proposed (see, for example, Patent Document 3). In addition, as a method for producing a graphene dispersion liquid, for example, a production method for making graphene into a dispersion liquid having a reduction step, a refinement step, an organic solvent mixing step, a strong stirring step, and a water removal step (see, for example, Patent Document 4) has been proposed. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Special Publication No. 2021-521288 [Patent Document 2] Special Publication No. 2021-523961 [Patent Document 3] International Publication No. 2017 / 047521 [Patent Document 4] International Publication No. 2017 / 047523 [Overview of the project] [Problems that the invention aims to solve]

[0005] For example, Patent Document 1 describes a composition comprising a carrier medium, a first corrosion inhibitor having a passivation mechanism, and a second corrosion inhibitor having a barrier mechanism. In this document, graphene is given as an example of a 2D material platelet. This method aims to improve corrosion resistance by combining the suppression of rust progression through passivation with the improvement of the barrier properties of the coating film by the 2D material. However, the first corrosion inhibitor needs to undergo a reaction to ionize and form a passivated layer at the site of rust occurrence, but the 2D material, which is the second corrosion inhibitor, has barrier properties, which can hinder the diffusion and movement of the first corrosion inhibitor after ionization, thus inhibiting the formation of the passivated layer, and there have been cases where this has resulted in problems with long-term durability.

[0006] For example, Patent Document 2 describes a graphene-based aqueous coating suspension comprising multiple graphene sheets, particles of an anticorrosive pigment or sacrificial metal, and an aqueous binder resin dissolved or dispersed in water. It states that this technology can reduce the amount of anode or sacrificial material (e.g., zinc particles) required compared to conventional methods. However, the examples only show electrochemical evaluation results, indicating that the initial corrosion potential is sufficient, but not long-term durability. In particular, when the amount of zinc is reduced, the zinc particles tend to become isolated, which can lead to premature localized wear and insufficient long-term durability.

[0007] On the other hand, expanding the range of applications for graphene requires technology to mold graphene into various shapes, and for this purpose, it is effective to disperse graphene in a single-layer or multi-layer thin-layer state. However, in a dispersion, thin-layer graphene tends to stack and aggregate, and the aggregated sheet-like graphene tends to entangle with each other. Further improvements in dispersibility in various compositions are needed for the technologies described in Patent Documents 3 and 4.

[0008] Furthermore, graphene composites, which combine graphene with inorganic particles, tend to have reduced dispersibility, so there has been a need for technologies to further improve dispersibility.

[0009] Therefore, the object of the present invention is to provide a graphene composite, a dispersion containing the graphene composite, a composition, and a formed product that can be obtained with superior dispersibility and corrosion resistance. [Means for solving the problem]

[0010] To solve the above problems, the present invention relates to a graphene composite comprising graphene particles and a metal phosphate or phosphate, wherein the metal phosphate or phosphate is present on the surface of the graphene particles, as well as a dispersion, composition, and product containing the graphene composite.

[0011] Specifically, the present invention has the following configuration.

[0012] (1) A graphene composite comprising graphene particles and a metal phosphate or phosphate, wherein the metal phosphate or phosphate is present on the surface of the graphene.

[0013] (2) The graphene composite according to (1) above, wherein a nitrogen-containing surface treatment agent is attached to the graphene particles without covalent bonding.

[0014] (3) The graphene composite according to (1) or (2) above, wherein the ratio of nitrogen to carbon (N / C ratio) of the graphene particles, as measured by X-ray photoelectron spectroscopy, is 0.005 or more and 0.200 or less.

[0015] (4) The graphene composite according to any one of (1) to (3) above, wherein the content of the phosphate or phosphate of the metal is 10% by weight or more and 1000% by weight or less relative to the weight of graphene particles.

[0016] (5) The graphene composite according to any one of (1) to (4) above, wherein the metal is an alkaline earth metal.

[0017] (6) A graphene complex dispersion containing any of the graphene complexes described in (1) to (5) above.

[0018] (7) The graphene composite dispersion according to (6) above, wherein the graphene dispersion further contains metallic zinc particles.

[0019] (8) A composition comprising the graphene composite dispersion liquid according to (6) or (7) above, and a curable resin and / or its precursor.

[0020] (9) The composition according to (8) above, wherein the content of the graphene composite is 0.01% by weight or more and 50% by weight or less based on the total solid content in the composition.

[0021] (10) A formed product containing the graphene composite according to any one of (1) to (5) above. [Effect of the Invention]

[0022] The graphene composite of the present invention has excellent dispersibility in a dispersion liquid or a composition, can improve the efficiency of forming a passive layer by a metal phosphate or phosphite which is a corrosion inhibitor pigment, and can obtain higher corrosion resistance when applied to a paint composition or the like. [Embodiments for Carrying Out the Invention]

[0023] [Metal Phosphate or Phosphite] The graphene composite of the present invention is a graphene composite containing graphene particles and a metal phosphate or phosphite, and has the metal phosphate or phosphite on the surface of the graphene particles.

[0024] In this specification, the graphene particles refer to the graphene main body, and the graphene composite refers to a composite of graphene particles and a metal phosphate or phosphite. Further, even when a surface treatment agent described later is further included in addition to the graphene particles and the metal phosphate or phosphite, it is also referred to as a graphene composite.

[0025] Metal phosphates and phosphates are known as anticorrosive pigments and can form a passivation layer that suppresses the progression of rust. Conventionally, when the anticorrosive pigment is not present on the surface of the graphene particles, but is mixed with the graphene particles and exists independently, the barrier effect created by the stacking of graphene particles may inhibit the diffusion of ions released by the anticorrosive pigment. On the other hand, in the present invention, since the anticorrosive pigment is present on the surface of the graphene particles, even if the graphene composite is stacked, the anticorrosive pigment is interposed between the graphene particles and functions as a spacer, so that a permeation path is secured and the movement and diffusion of ions generated from the anticorrosive pigment is less likely to be inhibited. Furthermore, the presence of anticorrosive pigment particles on the graphene particles inhibits the interaction between graphene composites, making it less likely for strong aggregation between graphene composites to occur, thus improving the dispersibility of the graphene composite in the dispersion or composition.

[0026] For example, when a dried powder is prepared from a graphene particle dispersion without the presence of a corrosion-preventive pigment on the graphene particles, irreversible aggregation can occur due to interactions between the graphene particles, making redispersion in the solvent difficult. On the other hand, as described above, the graphene composite of the present invention has a corrosion-preventive pigment interposed between the graphene particles, acting as a spacer, making irreversible aggregation less likely and improving redispersibility.

[0027] Furthermore, the presence of anticorrosive pigments on graphene particles increases the specific surface area of ​​the anticorrosive pigments, improving the ion release efficiency from the anticorrosive pigments and making it easier to form a passivation layer, thus further improving corrosion resistance.

[0028] In this specification, phosphates and phosphates may be collectively referred to as ()phosphates. Similarly, for example, magnesium phosphate and magnesium phosphate may be collectively referred to as ()magnesium phosphate.

[0029] The metal contained in the ()phosphate of the present invention preferably includes one or more metals selected from alkaline earth metals (e.g., magnesium, calcium, strontium, barium), silicon, aluminum, titanium, and zinc. Of these, from the viewpoint of excellent corrosion resistance, it is more preferable to include one or more metals selected from magnesium, calcium, barium, aluminum, or zinc, and even more preferable to include one or more metals selected from magnesium, calcium, or barium.

[0030] Furthermore, the above (phosphate) salts include, for example, hydroxyapatite (chemical formula: Ca 10 As exemplified by (PO4)6·(OH)2), it may have different ligands other than (phosphorous acid), such as a hydroxyl group. It may also be an amorphous mixture containing multiple types of (phosphorous acid) salts.

[0031] The phosphoric acid contained in the metal (phosphate) of the present invention may be polyphosphate, which is formed by the condensation of multiple phosphoric acids, such as diphosphate or triphosphate.

[0032] For example, when calcium is present, several different compositions are possible, and specific examples include calcium dihydrogen phosphate, calcium monohydrogen phosphate, tricalcium phosphate, octacalcium phosphate, hydroxyapatite, fluorineapatite, chlorineapatite, carbonateapatite, wittrockite, tetracalcium phosphate, and calcium pyrophosphate.

[0033] The composition of the metal (phosphate) salts of the present invention can be analyzed by X-ray diffraction (XRD).

[0034] The content of the metal ()phosphate in this invention is preferably 10% by weight or more and 1000% by weight or less relative to the weight of the graphene particles. If the content of the metal ()phosphate is 10% by weight or more relative to the weight of the graphene particles, the dispersion is easily improved by suppressing the stacking and aggregation between graphene composites, and corrosion resistance is easily improved. From the viewpoint of excellent corrosion resistance, 20% by weight or more is preferred, and 30% by weight or more is more preferred. On the other hand, if the weight ratio relative to the graphene particles is 1000% by weight or less, the dispersibility of the graphene composite is less likely to be impaired. From the viewpoint of further improving the dispersibility of the graphene composite, 800% by weight or less is preferred, 600% by weight or less is more preferred, and 500% by weight or less is even more preferred.

[0035] The content of the metal ()phosphate in this invention can be determined by performing the aforementioned XRD compositional analysis to identify the structure of the metal ()phosphate, and then using the same method as in Measurement Example 5 described below.

[0036] The content of metal ()phosphate in the graphene composite of the present invention can be easily adjusted by adjusting the ratio of the metal ()phosphate or its precursor to the graphene particles during the reaction and the reaction time.

[0037] The graphene composite of the present invention preferably has a coating area ratio of 1% or more and 100% or less with respect to metal ()phosphate. From the viewpoint of further improving corrosion resistance, it may preferably be 2% or more, 5% or more, 10% or more, 20% or more, 30% or more, or 40% or more. From the viewpoint of further improving the dispersibility of the graphene composite, it may preferably be 90% or less, 80% or less, 70% or less, 60% or less, or 50% or less.

[0038] The average particle size of the metal (phosphate) salt of the present invention is preferably 1 nm or more and 50 μm or less. From the viewpoint of further improving corrosion resistance, it may preferably be 10 nm or more, 50 nm or more, 100 nm or more, 500 nm or more, or 1 μm or more. From the viewpoint of further improving the dispersibility of the graphene composite, it may preferably be 40 μm or less, 20 μm or less, 10 μm or less, or 5 μm or less.

[0039] The average particle size of the metal ()phosphate of the present invention can be determined by the following method: A graphene composite is taken from a dispersion, composition, or formed product, and observed using an electron microscope with the field of view magnified to approximately 1 to 50 μm square so that the metal ()phosphate is within the field of view. The major and minor axes of five randomly selected metal ()phosphate particles on one graphene composite are measured and their arithmetic mean is calculated. The same measurement is then performed on 10 randomly selected different graphene composites, and the arithmetic mean is calculated and used as the value.

[0040] The average particle size of the metal ()phosphate in the graphene composite of the present invention can be easily adjusted by controlling the ratio of the metal ()phosphate or its precursor to the graphene particles during the reaction, as well as adjusting the reaction time.

[0041] The metal ()phosphate on the surface of the graphene particles of the present invention can be composited by either a method of precipitating the metal ()phosphate in the presence of graphene oxide or reduced graphene in one of the steps of the graphene composite manufacturing method described later, or by a method of mixing individually prepared metal ()phosphate with graphene oxide or reduced graphene. From the viewpoint of easily controlling the state of the metal ()phosphate, the method of precipitating the metal ()phosphate in the presence of graphene oxide or reduced graphene is preferred. It is thought that ions that serve as precursors to the metal ()phosphate coordinate to functional groups such as carboxyl groups on the graphene particles, creating crystal nuclei, and that crystals are generated starting from the surface of the graphene particles. The crystals generated on the graphene particles by this method are fine particles, and tend to have a smaller particle size and be more uniform than when they are individually prepared. As a result, the specific surface area is larger, the ion release when forming the passivation layer is improved, the efficiency of the metal ()phosphate as a corrosion-resistant pigment is improved, and corrosion resistance is further improved.

[0042] <Graphene particles> Generally, graphene, in the narrow sense, refers to a thickness of one atom of sp².2 While the term "graphene particle" generally refers to a sheet of bonded carbon atoms (single-layer graphene), in this specification, the term also includes forms that are stacked in a flaky manner. Similarly, the term "graphene oxide" also includes forms that are stacked in a flaky manner.

[0043] The graphene particles of the present invention can be graphene particles produced by known methods such as CVD, physical exfoliation, chemical exfoliation, and electroexfoliation. However, from the viewpoint of ease of compounding with the aforementioned metal ()phosphate, graphene particles produced by chemical exfoliation or electroexfoliation are preferred, and graphene particles produced by chemical exfoliation are more preferred.

[0044] Graphene particles produced by chemical stripping can be broadly classified into graphene oxide or reduced graphene oxide depending on the O / C ratio described later. In the present invention, either graphene oxide or reduced graphene oxide can be used, but it is more preferable to use reduced graphene oxide because having electrical conductivity tends to further improve rust prevention performance. When further combined with zinc particles described later, it is more preferable to use reduced graphene oxide because a higher effect is easily obtained.

[0045] The average thickness of the graphene particles of the present invention is preferably 0.3 nm or more and 100 nm or less. The theoretical minimum value for the average thickness of the graphene particles is 0.3 nm, indicating that they are single-layer graphene particles. On the other hand, by setting the average thickness of the graphene particles to 100 nm or less, it is possible to prevent a decrease in the dispersibility of the graphene composite. The average thickness of the graphene particles is more preferably 50 nm or less, even more preferably 20 nm or less, and even more preferably 10 nm or less.

[0046] The average thickness of the graphene particles of the present invention can be determined in the same manner as in Measurement Example 1 described later.

[0047] The average thickness of the graphene particles can be easily adjusted by controlling the stirring speed in the surface treatment and dispersion steps of the graphene composite manufacturing method described later, as well as by controlling the amount of surface treatment agent applied. Alternatively, commercially available graphene oxide having the desired average thickness may be used as a raw material, or commercially available graphene particles having the desired average thickness may be used.

[0048] From the viewpoint of further improving corrosion resistance, the size of the graphene composite in the planar direction is preferably 0.50 μm or more, and more preferably 1.0 μm or more. On the other hand, from the viewpoint of further improving the dispersibility of the graphene composite, it is preferably 100 μm or less, more preferably 50 μm or less, and even more preferably 20 μm or less.

[0049] The planar size of the graphene composite of the present invention can be determined in the same manner as in Measurement Example 2 described later.

[0050] The size of the graphene composite in the planar direction may be determined by using commercially available graphene oxide of the desired size as a raw material, or by using commercially available graphene particles of the desired size.

[0051] In the graphene composite of the present invention, it is preferable that the nitrogen-containing surface treatment agent is attached without covalent bonding. In this specification, "attached without covalent bonding" means that the graphene particles and the surface treatment agent are attached without forming covalent bonds. More specifically, this refers to the detection of molecules or fragments of the nitrogen-containing surface treatment agent in a temperature range of 100°C to 500°C, when approximately 2 mg of the graphene composite is analyzed by analytical methods such as thermal desorption GC-MS or TPD-MS, and the temperature is increased at a heating rate of 10°C / min under a helium flow atmosphere of 50 mL / min. If the surface treatment agent is bonded via covalent bonding, it will not be desorbed by such analytical methods and will be below the detection limit.

[0052] Nitrogen atoms impart a positive charge to surface treatment agents and can electrostatically adsorb to the negative charge of graphene particles. Compounds containing nitrogen contribute to improved dispersibility in dispersions and compositions by increasing the affinity of the graphene particle surface to the solvent. Furthermore, the lone pairs of electrons of nitrogen atoms can coordinate to metal cations that serve as precursors for metal ()phosphates, assisting in the formation of crystal nuclei on the graphene particle surface and facilitating the adhesion of metal ()phosphates.

[0053] The nitrogen atoms are preferably derived from primary amines, secondary amines, tertiary amines, quaternary ammonium salts, or nitrogen-containing cyclic compounds. The compound may contain two or more nitrogen atoms derived from these sources, or two or more nitrogen atoms derived from each of these sources.

[0054] The nitrogen-containing compound may be either low-molecular-weight or high-molecular-weight. Low-molecular-weight compounds are preferred for improved corrosion resistance, while high-molecular-weight compounds are preferred for improved durability. Here, low-molecular-weight compounds refer to compounds with a molecular weight of less than 1000, and high-molecular-weight compounds refer to compounds with a molecular weight of 1000 or more. Two or more nitrogen-containing compounds may be used.

[0055] When the nitrogen-containing compound is low molecular weight, aromatic compounds are preferably used to facilitate the attachment of the nitrogen-containing compound to graphene. Examples of aromatic compounds include 2-halogenated aniline, 3-halogenated aniline, 4-halogenated aniline, benzylamine, phenylethylamine, 1-naphthylamine, 2-naphthylamine, aniline, p-toluidine, m-toluidine, o-toluidine, 1-aminoanthracene, 2-aminoanthracene, 9-aminoanthracene, 1-aminopyrene, N-methylaniline, N-ethylaniline, N-isopropylaniline, 4-ethylaniline, 4-isopropylaniline, N,N-dimethylaniline, 4-nitroaniline, diphenylamine, N-methyldiphenylamine, 2,4,6-trimethylaniline, 4-methoxyaniline, N-methylbenzylamine, N,N-dimethylbenzylamine, N,N-diethylbenzylamine, benzamide, dopamine, phenylalanine, tyrosine, tryptophan, histidine, and their salts.

[0056] Other examples of polyamines include 1,6-diaminopyrene, 1,8-diaminopyrene, 1,4-phenylenediamine, 1,3-phenylenediamine, 1,2-phenylenediamine, 1,4-diaminoanthraquinone, 1,5-diaminonaphthalene, 1,8-diaminonaphthalene, 2,3-diaminonaphthalene, p-xylenediamine, m-xylenediamine, and 1,2,4-triaminobenzene.

[0057] When the nitrogen-containing compound is a low molecular weight compound and the solvent used for dispersion is an aliphatic hydrocarbon solvent, an aliphatic amine compound is preferably used. Examples of aliphatic amine compounds include amine compounds having 3 to 20 carbon atoms, such as propylamine, butylamine, pentylamine, hexylamine, heptylamine, octylamine, nonylamine, decylamine, dodecylamine, stearylamine, oleylamine, and their salts. The carbon chain may be cyclic or branched.

[0058] When the nitrogen-containing compound is a polymer, linear or branched polyetheramines are also preferably used, and it is preferable that they are liquid or waxy at room temperature. Furthermore, from the viewpoint of improving dispersibility, corrosion resistance, and adhesion, the polyetheramine preferably has one or more amino groups, and more preferably has two or more.

[0059] The weight-average molecular weight of the polyetheramine is preferably 140 or more and 10,000 or less. If the weight-average molecular weight is 140 or more, it exhibits excellent adhesion to the graphene powder surface, more preferably 200 or more, and even more preferably 500 or more. Furthermore, if the weight-average molecular weight is 10,000 or less, there is less concern about aggregation due to excessive adhesion, more preferably 8,000 or less, and even more preferably 6,000 or less.

[0060] The polyetheramine preferably contains a polyoxyethylene and / or polyoxypropylene structure. These structures facilitate surfactant activity and enhance the affinity between the solvent or resin and graphene. Examples of commercially available products containing such structures include polyethylene glycol #200, #300, #400, #600, #1000, #2000, "Uniox" (registered trademark) M-400, M-550, M-1000, and "Uniol" (registered trademark) D-200, D-250, D-400G, D-700, D-1000, D-1200, D-2000, D-4000, etc., manufactured by NOF Corporation.

[0061] The elemental ratio of oxygen to carbon (O / C ratio) of the graphene particles of the present invention, as measured by X-ray photoelectron spectroscopy, is preferably 0.05 or more and 0.60 or less. The O / C ratio represents the amount of functional groups on the graphene particles and serves as an indicator of the functionality of the graphene particles, such as dispersibility and conductivity. Generally, the O / C ratio of graphene particles obtained by physical exfoliation is often less than 0.05. For graphene particles obtained by chemical exfoliation, the O / C ratio is often 0.05 or more and less than 0.40 in the case of reduced graphene oxide, and often 0.40 or more in the case of graphene oxide.

[0062] From the viewpoint of further improving the dispersibility of the graphene composite in the dispersion or composition, an O / C ratio of 0.08 or higher is more preferable. Furthermore, from the viewpoint of further improving the functionality of the graphene particles, such as conductivity and barrier properties, a ratio of 0.30 or lower is more preferable, and 0.25 or lower is even more preferable.

[0063] The O / C ratio of the graphene particles of the present invention can be measured by the method described in Measurement Example 3 below. Note that in the graphene composite state, oxygen atoms contained in the metal ()phosphate are also detected; therefore, when measuring the O / C ratio of the graphene particles, the metal ()phosphate was dissolved and removed with acid before measurement.

[0064] The O / C ratio of graphene particles can be easily adjusted to the aforementioned range by, for example, adjusting the degree of oxidation of the raw material graphene oxide or the degree of reduction due to the reduction reaction conditions. Commercially available graphene particles with the desired O / C ratio may also be used.

[0065] The nitrogen-to-carbon atomic ratio (N / C ratio) of the graphene composite of the present invention, measured by X-ray photoelectron spectroscopy, serves as an indicator of the amount of nitrogen attached by the nitrogen-containing compound mentioned above. The attachment of the nitrogen-containing compound to the graphene particles increases the affinity of the graphene composite to the solvent and improves its dispersibility. The N / C ratio of the graphene composite is preferably 0.005 or higher, more preferably 0.007 or higher, and even more preferably 0.010 or higher. On the other hand, from the viewpoint of suppressing unintended aggregation, the N / C ratio of the graphene composite is preferably 0.200 or lower, more preferably 0.100 or lower, and even more preferably 0.050 or lower.

[0066] The N / C ratio of the graphene composite of the present invention can be measured by the method described in Measurement Example 4 below.

[0067] The N / C ratio of the graphene composite can be easily adjusted to the aforementioned range, for example, by the amount of nitrogen-containing compound attached.

[0068] <Graphene complex dispersion> The graphene composite of the present invention can be prepared as a graphene composite dispersion using water or an organic solvent. When using an organic solvent, it is preferable that it is capable of dissolving the curable resin and / or its precursor described later and is volatile, and can be appropriately selected depending on the coating properties of the composition. Specifically, it is preferable that it contains at least one selected from the group consisting of methyl isobutyl ketone, methyl ethyl ketone, acetone, butyl acetate, ethyl acetate, aliphatic hydrocarbon solvents, aromatic hydrocarbon solvents, and alcoholic solvents.

[0069] Examples of aliphatic hydrocarbon solvents include mineral oil, paraffin, kerosene, pentane, hexane, heptane, octane, nonane, and decane.

[0070] Examples of aromatic hydrocarbon solvents include xylene, toluene, ethylbenzene, mesitylene, cumene, tetramethylbenzene, n-hexylbenzene, cyclohexylbenzene, anisole, phenylcyclohexane, and halogenated benzenes.

[0071] Examples of alcohol-based solvents include hexanol, pentanol, n-butanol, isobutanol, isopropyl alcohol, ethanol, and methanol. Two or more of these may be included.

[0072] In this invention, the dispersibility of the graphene composite can be evaluated by measuring the absorbance when the graphene composite concentration is adjusted to 0.0065% by weight.

[0073] The absorbance of a graphene composite dispersion varies depending on the exfoliation and aggregation state of the graphene composite. A single-layer, non-aggregated graphene composite has the highest absorbance, and the absorbance decreases with increasing layer count and aggregation formation. A low absorbance at 500 nm indicates a low degree of exfoliation of the graphene composite, resulting in a state where much of the graphene composite is stacked and aggregated. The absorbance of the graphene composite at 500 nm is preferably 1.0 or higher, more preferably 1.4 or higher, and even more preferably 1.6 or higher. On the other hand, from the viewpoint of suppressing aggregation due to overdispersion of the graphene composite dispersion and improving dispersibility in the solvent, the absorbance of the graphene composite at 500 nm is preferably 2.5 or lower.

[0074] The absorbance of the graphene complex dispersion can be measured by the method described in Evaluation Example 1 below.

[0075] Furthermore, means of adjusting the absorbance of the graphene dispersion to the aforementioned range include, for example, adjusting the conditions described in the section on graphene composites, and obtaining the graphene dispersion by the manufacturing method described later.

[0076] <Curable resins and / or their precursors> A composition containing a curable resin and / or its precursor is preferably used together with the graphene composite dispersion of the present invention. A curable resin refers to a resin that hardens by the volatilization or reaction of a solvent, and examples include epoxy resins, urethane resins, acrylic resins, polyester resins, melamine resins, silicone resins, and alkyd resins. Commercially available curable resins for paint compositions can be suitably used. Two or more of these may be included. Among these, epoxy resins, urethane resins, and acrylic resins are preferred from the viewpoint of coatability and handling.

[0077] Examples of epoxy resins include bisphenol A type epoxy resin, bisphenol F type epoxy resin, novolac type epoxy resin, and modified versions thereof such as acrylic modified epoxy resin and urethane modified epoxy resin. Two or more of these may be included. Among these, bisphenol A type epoxy resin, bisphenol F type epoxy resin, and novolac type epoxy resin are preferred.

[0078] The epoxy equivalent of the epoxy resin is preferably between 100 and 5000. If the epoxy equivalent is 100 or more, the strength of the coating film obtained from the composition can be improved. On the other hand, if the epoxy equivalent is 5000 or less, the composition can be cured efficiently.

[0079] When an epoxy resin is included as the curable resin, it is preferable to further include an epoxy resin curing agent. Examples of epoxy resin curing agents include polyfunctional amine compounds and polyamidoamine compounds, and commercially available epoxy resin curing agents can be used. Two or more of these may be included. The active hydrogen equivalent of the epoxy resin curing agent is preferably 30 to 5000. If the active hydrogen equivalent is 30 or more, the strength of the coating film obtained from the composition can be improved. On the other hand, if the active hydrogen equivalent is 5000 or less, the composition can be cured efficiently.

[0080] <Composition> The composition may further contain a solvent and / or optional additives. The solvent is preferably one that can dissolve the curable resin and / or its precursor and is volatile, and can be appropriately selected depending on the coating properties of the composition.

[0081] The composition preferably further contains zinc particles. Zinc particles can provide long-term corrosion protection through a sacrificial corrosion protection effect. Furthermore, the metal ()phosphate of the present invention forms a stronger passivation layer in the presence of zinc ions. The white rust generated by the sacrificial corrosion protection effect of zinc particles and the metal ()phosphate combine to form an even stronger corrosion protection layer.

[0082] In such cases, the zinc particle content is preferably 10% by weight or more and 80% by weight or less relative to the total solid content in the composition.

[0083] The graphene composite content in the composition of the present invention is preferably 0.01% by weight or more and 50% by weight or less of the total solid content of the composition. By setting the graphene composite content to 0.01% by weight or more, corrosion resistance and durability can be further improved due to the shielding effect of graphene and the formation of a conductive network. From the viewpoint of improving corrosion resistance, the graphene content is more preferably 0.1% by weight or more, and even more preferably 0.5% by weight or more, of the total solid content of the composition. On the other hand, by setting the graphene content to 50% by weight or less, aggregation of the graphene composite in the composition can be suppressed, and corrosion resistance can be further improved. The graphene composite content is more preferably 40% by weight or less, and even more preferably 30% by weight or less, of the solid content of the composition.

[0084] <Formation> The product containing the graphene composite of the present invention is preferably used as a corrosion-resistant product such as a rust-preventive paint. For example, a composition containing a graphene composite dispersion in which the graphene composite of the present invention is dispersed in an organic solvent can be formed in a film-like manner on a metal substrate such as steel to obtain the product.

[0085] <Method for manufacturing graphene composites> The graphene composite of the present invention can be produced, for example, by mixing graphene oxide and a nitrogen-containing compound in a solvent, then subjecting it to a reduction treatment, and adding and mixing a precursor of a metal ()phosphate to precipitate the metal ()phosphate on the surface of the graphene particles.

[0086] [Graphene oxide] Examples of methods for producing graphene oxide include the Hammers process. Alternatively, commercially available graphene oxide can be purchased. The following is an example of a method using the Hammers process for producing graphene oxide.

[0087] While in an ice bath, add graphite (calcium powder) and sodium nitrate to concentrated sulfuric acid and stir, gradually adding potassium permanganate while keeping the temperature from rising, and stirring for 0.2 to 5 hours while maintaining a temperature range of 25 to 50°C. Then, dilute with deionized water to make a suspension and stir at a temperature range of 80 to 100°C for 5 to 50 minutes. After that, add hydrogen peroxide and deionized water and stir for 1 to 30 minutes to obtain a graphene oxide aqueous dispersion. Filter and wash the obtained graphene oxide aqueous dispersion to obtain a graphene oxide wet cake.

[0088] Natural graphite is preferred as the graphite, and the mesh count is preferably 5000 or less. For 10g of natural graphite, the amount of sodium nitrate added is preferably 2-8g, the amount of concentrated sulfuric acid added is preferably 150-300ml, the amount of potassium permanganate added is preferably 10-40g, the amount of hydrogen peroxide added is preferably 40-80g, and the amount of deionized water added is preferably 10-20 times the amount of hydrogen peroxide added. The degree of oxidation of graphene oxide can be adjusted to a desired range by, for example, the amount of oxidizing agent added, such as sodium nitrate or potassium permanganate. Specifically, the ratio of the amount of sodium nitrate added to graphite (sodium nitrate / graphite) is preferably 0.200 to 0.800, and the ratio of the amount of potassium permanganate added to graphite (potassium permanganate / graphite) is preferably 1.0 to 4.0.

[0089] [Surface treatment process] Next, graphene oxide and a nitrogen-containing compound are mixed, and the nitrogen-containing compound is applied to the graphene oxide as a surface treatment agent. To ensure good mixing of graphene oxide and the nitrogen-containing compound, it is preferable to mix them while both are dispersed in the solvent. In this case, it is preferable that both graphene oxide and the nitrogen-containing compound are completely dissolved, but it is also acceptable for some to remain dispersed as solids without dissolving. As a mixing method, a disperser that employs a dispersion stirring type, a rotor / stator type, etc. is preferable. Examples of such dispersers include, for example, "Lab Revolution" (registered trademark) Homodisper 2.5 type (Primix Corporation), Disperser PH91 (SMT Corporation), "Silver Son Mixer" (registered trademark) L5M-A (Silver Son Nippon Corporation), and the like.

[0090] [Reduction step] Next, graphene oxide is reduced and converted into reduced graphene oxide. As the reduction method, chemical reduction is preferable. In the case of chemical reduction, examples of the reducing agent include organic reducing agents and inorganic reducing agents. Among these, examples of the organic reducing agent include hydrazine or sodium ascorbate. Examples of the inorganic reducing agent include sodium dithionite, sodium borohydride, and zinc particles.

[0091] When zinc particles are used as the reducing agent, it is preferable because it can be directly incorporated into the anti-rust paint, simplifying the post-purification.

[0092] [Composite formation step with metal (meta)phosphate] For the slurry after reduction, a precursor of metal (meta)phosphate is mixed to precipitate metal (meta)phosphate on the surface of graphene particles, obtaining a graphene composite. As an example of the precursor, for example, after adding an organic phosphate such as diammonium hydrogen phosphate, metal nitrates such as calcium nitrate are dropped little by little while stirring and mixing, and metal (meta)phosphate precipitates. In such a precipitation reaction, pH control is important. For example, in the precipitation of calcium phosphate, it is preferable to carry out the reaction under basic conditions with pH = 11.

[0093] [Filtration and concentration step] Next, the obtained graphene composite slurry is concentrated by filtration. The filtration concentration step is a step in which a portion of the solvent in the graphene composite slurry is removed by filtration. As for filtration, vacuum filtration is preferred from the viewpoint of suppressing the graphene composite from being firmly compressed and aggregated. Alternatively, the operation of redispersing the obtained graphene composite dispersion in the solvent and concentrating by filtration may be repeated multiple times. In the present invention, it is preferable to perform the filtration concentration step two to six times.

[0094] [Dispersion process] The graphene composite obtained in the filtration and concentration step is redispersed in an organic solvent. In the dispersion step, it is preferable to stir the slurry of the graphene composite mixed with the organic solvent using a disperser, rotor / stator type, or similar disperser. The higher the peripheral speed when stirring the slurry, the more efficiently the graphene composite, which has been layered by shear force, can be detached, thereby eliminating aggregation and further improving the dispersibility of the graphene composite in the dispersion.

[0095] [Drying process] The resulting graphene composite dispersion may be further processed to obtain a dry graphene composite powder by removing the solvent. When drying into a powder, it is preferable to use freeze-drying or spray-drying to reduce irreversible aggregation of the graphene composite.

[0096] <Method for producing the composition> Next, examples of methods for producing compositions using graphene composite dispersions will be described. For example, a method of mixing the graphene composite dispersion with a curable resin and / or its precursor, inorganic particles, and optionally a solvent and any additives, or a method of mixing the graphene composite with a commercially available paint composition containing inorganic particles, a curable resin and / or its precursor. In the former method, the inorganic particles and the graphene composite dispersion may be added and mixed simultaneously, or they may be added and mixed separately. From the viewpoint of further improving the dispersibility of the graphene composite, it is preferable to mix the graphene composite and inorganic particles with a solution in which the curable resin and / or its precursor is dissolved in a solvent.

[0097] Mixing equipment includes, for example, bead mills, homodispers, homomixers, planetary mixers, sand mills, and other mixers and kneaders.

[0098] If the composition of the present invention contains a curable resin precursor, the main component (e.g., epoxy resin) and the curing agent (e.g., epoxy resin curing agent) may be stored in separate containers until immediately before use. In this case, the graphene composite and inorganic particles may be contained in the main component or in the curing agent.

[0099] Examples of inorganic particles include extender pigments commonly used in paints. When the composition of the present invention is used as a protective coating, the corrosion resistance of the cured product can be further improved by selecting a material with a high sacrificial corrosion protection effect, depending on the object being protected. For example, when used as a protective coating for steel, selecting zinc particles as the inorganic material can further improve the corrosion resistance and durability of the cured product through the sacrificial corrosion protection effect.

[0100] The inorganic particles preferably include zinc, iron oxide, mica, talc, bentonite, silicon dioxide, titanium oxide, aluminum oxide, barium sulfate, stainless steel, glass, and aluminum. Two or more of these may be included.

[0101] Examples of inorganic particle shapes include spherical, flake-like, flaky, fibrous, and irregular shapes.

[0102] Among these, mica, talc, bentonite, flaky titanium oxide, stainless steel flakes, glass flakes, and aluminum flakes have a high shielding effect due to their flattened shape, which can further improve the corrosion resistance of the cured product. In addition, zinc particles have a high sacrificial corrosion protection effect, which can further improve the corrosion resistance of the cured product. It is preferable to combine zinc particles with talc, bentonite, glass flakes, etc., and the viscosity of the composition and the mechanical properties of the coating obtained from the composition can be easily adjusted to a desired range.

[0103] The average particle size of the inorganic particles is preferably 40 μm or less, more preferably 30 μm or less, and even more preferably 20 μm or less, from the viewpoint of suppressing defects such as pinholes and further improving the corrosion resistance of the cured product. On the other hand, from the viewpoint of enhancing the shielding effect and sacrificial corrosion protection effect of the inorganic particles and further improving the corrosion resistance and durability of the cured product, it is preferably 1.0 μm or more, more preferably 3.0 μm or more, and even more preferably 5.0 μm or more. The average particle size of the inorganic particles can be easily adjusted to the above range using known particle grinding techniques. Alternatively, commercially available inorganic particles with the desired particle size can be purchased and used.

[0104] The products formed by the present invention include the graphene composite of the present invention and refer to those formed by molding the composition of the present invention into a desired shape on a substrate or the like. For example, these include coatings and cast bodies before and after drying. Specific examples are shown below.

[0105] The composition containing the graphene composite dispersion of the present invention can be used as a corrosion-resistant material by forming it by coating or casting, and then curing it by drying or reaction. Furthermore, the effect is more easily obtained by forming the composition in a film on a metal substrate. For example, it can be suitably used as a coating material such as a corrosion-resistant paint.

[0106] Examples of the aforementioned metal substrates include metal casings and components, steel casings and structures (vehicles such as automobiles and ships, structures such as bridges and steel bridges, factory equipment, etc.).

[0107] The composition of the present invention can be suitably used as a coating film formed by applying it to a substrate and drying it. Examples of application methods include applicator application, bar coating, spin coating, roller application, brush application, and spray application. The drying method can be appropriately selected depending on the solvent, resin, and application, and examples include natural drying, heat drying, and hot air drying.

[0108] The composition of the present invention may be used, for example, by injecting it into a crack and curing it by drying and / or a crosslinking reaction. Known methods can be used for injection and curing.

[0109] The corrosion resistance of the composition of the present invention can be evaluated in the same manner as in Evaluation Example 2 described below. A steel plate coated with the composition of the present invention and dried is immersed in a 5% by weight aqueous sodium chloride solution under neutral conditions, left to stand for 24 hours, then removed, washed with water, and dried. The corrosion resistance can then be evaluated by whether or not red rust is observed on the surface. It is preferable that no red rust is observed. [Examples]

[0110] The present invention will be described below with reference to examples.

[0111] First, the evaluation methods for each example and comparative example will be explained. Since the average thickness of the graphene particles, the size of the graphene composite in the planar direction, the O / C ratio of the graphene particles, and the N / C ratio of the graphene composite do not change between the composition and the graphene composite dispersion, the analysis was performed using the graphene composite dispersion.

[0112] [Measurement Example 1] Average thickness of graphene particles The graphene composite dispersions prepared in the examples and comparative examples were diluted with N-methylpyrrolidone to a concentration of 0.001% by weight. A dilution was prepared by processing with a Homodisper 2.5 type (Primix) at a rotation speed of 3,000 rpm for 30 minutes. The prepared dilution was dropped onto a PET film, dried, and embedded in resin. After cross-sectioning, an observation sample was prepared by ion milling. The observation sample was observed using a transmission microscope JEM-F200 (JEOL Ltd.) at an accelerating voltage of 200 kV. The graphene composite was magnified to an appropriate magnification so that the thickness direction of one graphene composite was included in the field of view. The thickness of the graphene particles was measured at five randomly selected locations for one graphene composite, and the arithmetic mean was calculated. The same analysis was then performed on 10 randomly selected graphene composites, and the arithmetic mean was calculated. In measuring the thickness of the graphene particles, the thickness of the area where the layered structure of the graphene particles is observed was measured, and the thickness of metal ()phosphates was not included in the thickness.

[0113] [Measurement Example 2] Planar size of graphene composite A diluted graphene composite was prepared in the same manner as in Measurement Example 1. The diluted solution was dropped onto a mica substrate and dried to adhere the graphene composite to the substrate. The graphene composite on the substrate was observed at a magnification of 30,000x using an electron microscope S-5500 (manufactured by Hitachi High-Technologies Corporation). For 10 randomly selected graphenes, the length of the longest part (major axis) and the length of the shortest part (minor axis) in the direction parallel to the graphene layer were measured. The size in the direction parallel to the graphene layer was calculated by taking the arithmetic mean of the values ​​obtained by (major axis + minor axis) / 2.

[0114] [Measurement Example 3] O / C ratio of graphene particles A graphene composite dilution was prepared in the same manner as in Measurement Example 1, the graphene composite was recovered by filtration under reduced pressure, and the mixture was vacuum-dried overnight to obtain a dry powder of the graphene composite. The metal ()phosphate was removed using an acid capable of dissolving it, such as nitric acid or hydrochloric acid, and the mixture was washed with distilled water and filtered five times. The resulting filtrate was vacuum-dried to obtain graphene particles from which the metal ()phosphate had been removed. The obtained graphene particles were subjected to photoelectron spectroscopy using an X-ray photoelectron spectrometer, Quantera SXM (ULVAC-PHIE). The excitation X-ray was monochromatic AlK α1,2 The X-ray beam was set to 1486.6 eV, with an X-ray diameter of 200 μm and a photoemission angle of 45°. The main C1s peak, based on carbon atoms, was assigned to 284.3 eV, and the O1s peak, based on oxygen atoms, was assigned to a peak around 533 eV. The O / C ratio was calculated from the area ratio of the O1s peak to the C1s peak, and the resulting value was rounded to two decimal places.

[0115] [Measurement Example 4] N / C ratio of graphene composite Similar to Measurement Example 3, a dried graphene composite powder was prepared, and the resulting dried powder was subjected to photoelectron spectroscopy using an X-ray photoelectron spectrometer, Quantera SXM (manufactured by ULVAC-PHI, Inc.). The excitation X-ray was monochromatic AlK α1,2 The X-ray beam was set to 1486.6 eV, with an X-ray diameter of 200 μm and a photoelectron escape angle of 45°. The main C1s peak, based on carbon atoms, was assigned to 284.3 eV, and the N1s peak, based on nitrogen atoms, was assigned to a peak around 402 eV. The N / C ratio was calculated from the area ratio of the N1s peak to the C1s peak, and the resulting value was rounded to the third decimal place.

[0116] [Measurement Example 5] Content of metal phosphates or phosphates relative to the weight of graphene particles A dried powder of the graphene composite was prepared in the same manner as in Measurement Example 4. 10 mg of the graphene composite powder was weighed into a platinum crucible, heated and ashed using a hot plate and burner, and then weighed again. The weight loss was taken as the weight of the graphene particles. The obtained ashed material was dissolved in sodium carbonate, water was added and heated to dissolve it, then nitric acid was added and the volume was adjusted with water. The elemental concentration of the metal in the metal ()phosphate of this solution was measured by ICP emission spectrometry. The weight of the metal ()phosphate contained in the graphene composite was determined by multiplying the obtained elemental concentration, the volume of the solution, and the molecular weight of the metal ()phosphate. The weight of the metal ()phosphate relative to the weight of the graphene particles was determined by dividing the weight of the metal ()phosphate by the weight of the graphene particles.

[0117] [Evaluation Example 1] Absorbance of graphene complex dispersion The absorbance of the graphene composite dispersions prepared in the examples and comparative examples was measured using a "UV7" (registered trademark) spectrophotometer (Mettler Toledo). A quartz cell with a path length of 10 mm was used. The same organic solvent as the dispersion solvent was added to the prepared graphene composite dispersion so that the graphene composite concentration was 0.0065% by weight. The diluted solution was treated for 10 minutes at high output setting using an ultrasonic cleaner (ASU-6M, AS ONE Corporation) with an output of 130 W and an oscillation frequency of 40 kHz. A baseline measurement was performed in advance using the organic solvent used for concentration adjustment, and then the absorbance was measured.

[0118] [Evaluation Example 2] Corrosion resistance of compositions containing graphene composites The compositions prepared according to the examples and comparative examples were applied using a spray gun to a sandblasted general structural rolled steel sheet (material: SS400) measuring 15 cm × 7 cm × 0.8 cm thick, dried at room temperature, and left to stand for one day to form a cured film. The thickness of the cured film was adjusted to 30 ± 10 μm. For exposed substrate areas where the cured film had not formed, a commercially available rust-preventive paint (Nippon Paint Co., Ltd. "Zinky" (registered trademark) 8000HB) was applied using a brush, dried, and left to stand for one week to cure, obtaining test plates. The obtained test plates were immersed in a 5% by weight sodium chloride aqueous solution under neutral conditions, left to stand for 24 hours, removed, washed with water, and dried, and it was determined whether or not red rust was observed on the surface.

[0119] [Synthesis Example 1: Preparation of Graphene Oxide] Using 1500 mesh natural graphite powder (Shanghai Yifan Graphite Co., Ltd.) as the raw material, 10 g of natural graphite powder was added to an ice bath, along with 220 ml of 98% concentrated sulfuric acid, 5 g of sodium nitrate, and 30 g of potassium permanganate. The mixture was mechanically stirred for 1 hour while maintaining the temperature of the mixture below 20°C. This mixture was removed from the ice bath and stirred in a 35°C water bath for 4 hours. Then, 500 ml of deionized water was added, and the resulting suspension was stirred further at 90°C for 15 minutes. Finally, 600 ml of deionized water and 50 ml of hydrogen peroxide were added, and the mixture was stirred for 5 minutes to obtain a graphene oxide dispersion. This was filtered while still hot, metal ions were washed with dilute hydrochloric acid solution, and the acid was washed with deionized water. The washing was repeated until the pH reached 7, and the dispersion was concentrated by suction filtration to prepare a 45 wt% graphene oxide wet cake. The elemental ratio of oxygen atoms to carbon atoms (O / C ratio) of the prepared graphene oxide, as measured by X-ray photoelectron spectroscopy, was 0.53.

[0120] [Example 1] (Preparation of graphene complex) 11.1 g (5 g solid) of 45% by weight graphene oxide wet cake prepared according to Synthesis Example 1 was diluted to a concentration of 0.5% by weight with 988.9 g of deionized water and processed using a Homodisper 2.5 type (Primix) at a rotation speed of 3,000 rpm for 30 minutes to obtain a homogeneous graphene oxide dispersion. A 25% aqueous solution of sodium hydroxide manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. was added to adjust the pH to 8.5, and 1.6 g of phenylethylamine hydrochloride manufactured by Tokyo Chemical Industry Co., Ltd. was mixed in as a surface treatment agent. The mixture was then processed using a Homodisper 2.5 type (Primix) at a rotation speed of 3,000 rpm for 60 minutes. 10 g of zinc particles manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. were added to the graphene oxide dispersion, and reduction was performed by stirring using a Homodisper 2.5 type (Primix) at a rotation speed of 2,000 rpm for 30 minutes. A reduced graphene oxide dispersion was prepared by adding 3 g of calcium nitrate monohydrate manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. and dissolving it, then adding a 25% aqueous solution of sodium hydroxide manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. to adjust the pH to 11. 1 g of diammonium hydrogen phosphate was weighed into a separate container and dissolved in 50 g of deionized water. This solution was then added dropwise using a dropper and stirred at 2,000 rpm for 30 minutes using a Homodisper 2.5 (Primix Corporation) to obtain a graphene complex aqueous dispersion. The dispersion was then filtered using a vacuum suction filter, and the washing process was repeated twice, diluting with water to a concentration of 0.5% by weight and filtering by suction, to obtain a graphene complex aqueous wet cake. The obtained graphene complex aqueous wet cake was diluted with deionized water to a concentration of 1% by weight and redispersed by stirring at 10,000 rpm for 5 minutes using a "Silverson Mixer" (registered trademark) L5M-A (Silverson Nippon Co., Ltd.). 100 g of the obtained graphene composite aqueous dispersion was placed in a 1000 mL pear-shaped flask and frozen with liquid nitrogen so that it adhered thinly to the inner wall of the flask. Freeze-drying was then carried out for 12 hours using an "EYELA" (registered trademark) freeze-dryer FDU-1200 (Tokyo Rikakikai Co., Ltd.) at a temperature of -30°C or lower and a pressure of 30 Pa or lower to obtain graphene composite powder. This operation was repeated multiple times until the required amount of graphene composite powder was obtained.The obtained graphene composite powder was added to 1-butanol solvent to a concentration of 1.5% by weight, and redispersed using a Silverson mixer L5M-A at a rotation speed of 10,000 rpm for 20 minutes to prepare a graphene composite dispersion. The average thickness of the graphene particles, the size of the graphene composite in the planar direction, the O / C ratio of the graphene particles, and the N / C ratio of the graphene composite were measured using the methods described in Measurement Examples 1 to 4, and the results are shown in Table 1. In addition, the dispersibility of the graphene composite was evaluated using the method described in Evaluation Example 1, and the results are shown in Table 1.

[0121] (Preparation of composition) 30 g of DIC Corporation's "Epiclon" (registered trademark) 850 (bisphenol A type epoxy resin, epoxy equivalent 183-193 g / eq) was weighed out as epoxy resin, 20 g of xylene was added, and the mixture was stirred using a magnetic stirrer at 300 rpm for 20 minutes. 4.9 g of talc and 5 g of bentonite from Fujifilm Wako Pure Chemical Industries, Ltd. were added to the resulting solution, and the mixture was homogenized by stirring at 3,000 rpm for 10 minutes using a Homodisper 2.5 type (Primix). 6.67 g (1% by weight of the total solid weight) of the aforementioned 1.5% by weight graphene complex butanol dispersion was added, and the mixture was stirred at 3,000 rpm for 10 minutes using a Homodisper 2.5 type (Primix). Furthermore, 30 g of zinc powder (average particle size 10 μm) manufactured by Hayashi Pure Chemical Industries, Ltd. was added and the mixture was homogenized by stirring at 3,000 rpm for 30 minutes using a Homodisper 2.5 type (Primix Corporation). 42.85 g of Newmid 515 (trade name) manufactured by Harima Chemicals Group Co., Ltd. (polyamideamine, active hydrogen equivalent 185, solid content 70% by weight, solid weight 30 g) was added as an epoxy resin curing agent, and the mixture was further homogenized by stirring at 3,000 rpm for 10 minutes using a Homodisper 2.5 type (Primix Corporation) to prepare the composition.

[0122] The obtained compositions were applied to steel plates and dried using the method described in Evaluation Example 2 to form molded products, and their corrosion resistance was evaluated. The results are shown in Table 1.

[0123] [Comparative Example 1] A graphene particle dispersion was prepared in the same manner as in Example 1, except that calcium nitrate monohydrate, a precursor of metal ()phosphate, and diammonium hydrogen phosphate were not used. Analysis of the dispersion was performed in Measurement Examples 1-4 and Evaluation Example 1, and the results are shown in Table 1. In addition, a composition was prepared and evaluated in the same manner as in Example 1, and the results are shown in Table 1.

[0124] [Table 1]

Claims

1. A graphene composite comprising graphene particles and a metal phosphate or phosphate, wherein the metal phosphate or phosphate is present on the surface of the graphene particles.

2. The graphene composite according to claim 1, wherein a nitrogen-containing surface treatment agent is attached to the graphene particles without covalent bonding.

3. The graphene composite according to claim 2, wherein the ratio of nitrogen to carbon (N / C ratio) of the graphene particles, as measured by X-ray photoelectron spectroscopy, is 0.005 or more and 0.200 or less.

4. The graphene composite according to claim 1, wherein the content of the phosphate or phosphate of the aforementioned metal is 10% by weight or more and 1000% by weight or less relative to the weight of graphene particles.

5. The graphene composite according to claim 4, wherein the metal is an alkaline earth metal.

6. A graphene complex dispersion containing the graphene complex described in any one of claims 1 to 5.

7. The graphene composite dispersion according to claim 6, wherein the graphene dispersion further contains metallic zinc particles.

8. A composition comprising a graphene composite dispersion according to claim 6 and a curable resin and / or its precursor.

9. The composition according to claim 8, wherein the content of the graphene composite relative to the total solids in the composition is 0.01% by weight or more and 50% by weight or less.

10. A product comprising the graphene composite according to any one of claims 1 to 5.

Images