JP2015196632A - Boron nitride nanosheet-containing fluid dispersion and production method thereof, and boron nitride nanosheet composite and production method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a boron nitride nanosheet-containing fluid dispersion in which the boron nitride nanosheet is highly dispersed in superacid, and a boron nitride nanosheet composite that has an excellent dispersibility in solvent or resin.SOLUTION: Provided is a boron nitride nanosheet-containing fluid dispersion characterized in comprising superacid and a boron nitride nanosheet dispersed therein, and a boron nitride nanosheet composite characterized in comprising a boron nitride nanosheet and superacid adsorbed thereon.

Description

  The present invention relates to a boron nitride nanosheet-containing dispersion and a production method thereof, a boron nitride nanosheet composite, and a production method thereof.

  Carbon nanostructures are attracting attention because they are excellent in thermal conductivity, electrical conductivity, mechanical properties, and storage stability. For example, electronic device materials, microscope probes, emitters for field emission displays, lithium secondary Developments are underway for application expansion to battery negative electrodes, field effect transistors, drug delivery system materials, composite materials with resins and ceramics, molecular storage materials, and the like. Since such a carbon nanostructure has extremely poor dispersibility in solvents, resins, metals, and ceramics, improvement in dispersibility has been desired. In recent years, the characteristics of graphene composed of one or several layers obtained by exfoliating graphite have attracted attention, and research is actively conducted all over the world for application development to various applications.

  On the other hand, hexagonal boron nitride is a layered material having a structure similar to graphite, and has high thermal conductivity, high insulation, high heat resistance, high slidability, low thermal expansion coefficient, high oxidation resistance, high It is known that it is excellent in characteristics such as chemical stability and far-ultraviolet light emission characteristics. For example, it is known that various functions can be imparted to the resin by compounding with the resin. In particular, boron nitride nanosheets have a very large specific surface area compared to boron nitride and have a two-dimensional planar structure, so by compounding with resin, further improving the functionality of the resin composite, Functionality is expected by adding a small amount to the resin. Furthermore, since boron nitride nanosheets exhibit high insulation, they are used for various parts of moving media such as automobiles and various parts for electric and electronic devices that require both high thermal conductivity and insulating properties. Applications are also expected. However, since boron nitride is superior in chemical stability and extremely high in oxidation resistance compared to graphite, it is difficult to use a chemical reaction such as oxidation treatment in the removal of boron nitride. Since the interaction between the layers is stronger than the van der Waals force between the graphite layers, it has been a problem that the peeling of boron nitride is not easy.

  In order to solve such a problem, Japanese Patent Application Laid-Open No. 2011-79751 (Patent Document 1) discloses a hexagonal boron nitride sheet in which a multilayered layer is peeled off and has a three-layer structure. Ultra-thin boron nitride nanosheets containing crystalline boron nitride, as well as a comparatively strong ultra-dispersed dispersion of hexagonal boron nitride powder dispersed in a specific organic solvent having a relatively high affinity with boron nitride such as dimethylformaldehyde A method for producing an ultrathin boron nitride nanosheet is disclosed, which is subjected to sonication, followed by centrifugation and drying. However, the ultrathin boron nitride nanosheet disclosed in Patent Document 1 and the production method thereof have a low yield of about 0.1% of the obtained boron nitride nanosheet, and have a number of layers of 2 or less. Obtaining boron nitride nanosheets was difficult and not always sufficient.

  JP 2012-255055 A (Patent Document 2) discloses an inorganic-organic composite composition having a structure in which boron nitride particles as a high thermal conductive filler are dispersed in a state of exfoliated flat particles in a resin as a matrix. The composite material and the secondary particles of boron nitride particles, which are laminates of primary particles, are peeled flat by performing a peeling step in a liquid using a wet jet mill at a high shear rate under high pressure in a liquid. There is disclosed a method for producing a composite material in which particles are obtained and dispersed as a high thermal conductive filler in a resin as a matrix so that boron nitride particles and the resin are combined. However, it is difficult to efficiently produce a boron nitride nanosheet having a small number of layers such as 10 or less in the composite material composed of the inorganic-organic composite composition disclosed in Patent Document 2 and the production method thereof. It was not always enough. In Patent Documents 1 and 2, since high shear is imparted to boron nitride by powerful ultrasonic treatment or use of a wet jet mill, boron nitride nanosheets due to damage to the hexagonal sheet structure of boron nitride nanosheets However, this was not always sufficient.

  Furthermore, since boron nitride nanosheets have high interaction between layers, there is a problem that even if they are physically peeled once, dispersion stability in solvents and resins is low, and reaggregation tends to occur. For application, it has been demanded to improve dispersion stability in a solvent.

JP 2011-79751 A JP 2012-255055 A

  The present invention has been made in view of the above-described problems of the prior art, and a boron nitride nanosheet-containing dispersion in which boron nitride nanosheets are highly dispersed in superacid, and a method for producing the same, dispersion in a solvent or resin An object of the present invention is to provide a boron nitride nanosheet composite having excellent properties and a method for producing the same.

  As a result of intensive studies to achieve the above object, the present inventors have surprisingly obtained a boron nitride nanosheet-containing dispersion obtained by coexisting a superacid and a boron nitride nanosheet. The present invention is completed by finding that it is highly dispersed in an acid, and that the resulting boron nitride nanosheet composite can be excellent in dispersibility in a solvent or resin. It came to.

  That is, the boron nitride nanosheet-containing dispersion of the present invention is characterized by comprising a superacid and a boron nitride nanosheet dispersed in the superacid.

  In the boron nitride nanosheet-containing dispersion of the present invention, it is preferable that at least a part of the superacid is adsorbed on the boron nitride nanosheet.

  Moreover, in the boron nitride nanosheet containing dispersion liquid of this invention, it is preferable that the said boron nitride nanosheet contains the boron nitride nanosheet whose number of layers is 10 layers or less.

  In the method for producing a dispersion containing boron nitride nanosheets of the present invention, boron nitride and superacid are mixed, the layers of boron nitride are peeled to obtain boron nitride nanosheets, and dispersed in the superacid and superacid. A boron nitride nanosheet-containing dispersion comprising the boron nitride nanosheet.

  In the method for producing a boron nitride nanosheet-containing dispersion according to the present invention, the mixing is at least one layer selected from the group consisting of ultrasonic treatment, stirring treatment and pulverization treatment of the boron nitride in the presence of the super acid. It is preferable to include a step of performing a peeling treatment.

  The boron nitride nanosheet composite of the present invention comprises a boron nitride nanosheet and a superacid adsorbed on the boron nitride nanosheet.

  In the boron nitride nanosheet composite of the present invention, the boron nitride nanosheet preferably includes a boron nitride nanosheet having 10 or less layers.

  The boron nitride nanosheet composite-containing dispersion of the present invention contains the boron nitride nanosheet composite of the present invention and a solvent other than superacid.

  In the method for producing a boron nitride nanosheet composite of the present invention, boron nitride and a superacid are mixed, the layers of the boron nitride are separated to obtain a boron nitride nanosheet, and the superacid is adsorbed on the boron nitride nanosheet. It is the method characterized by this.

  In the method for producing a boron nitride nanosheet composite of the present invention, the mixing is at least one type of delamination selected from the group consisting of ultrasonic treatment, stirring treatment, and pulverization treatment of the boron nitride in the presence of the superacid. It is preferable to include the process of giving a process.

  The boron nitride nanosheet thin layered body of the present invention is obtained by removing superacid adsorbed on the boron nitride nanosheet composite obtained by the method for producing a boron nitride nanosheet composite of the present invention. It is characterized by.

  The method for producing a thin layer of boron nitride nanosheet according to the present invention uses a boron nitride nanosheet composite obtained by the method for producing a boron nitride nanosheet composite according to the present invention, and is adsorbed on the boron nitride nanosheet composite. It is a method characterized by obtaining a boron nitride nanosheet thin layer by removing acid.

The boron nitride nanosheet-containing dispersion of the present invention and the production method thereof, the boron nitride nanosheet composite and the production method thereof, boron nitride nanosheet-containing dispersion in which boron nitride nanosheets are highly dispersed in superacid, and boron nitride The reason why the nanosheet composite is excellent in dispersibility in a solvent or resin is not necessarily clear, but the present inventors speculate as follows. That is, in the boron nitride nanosheet-containing dispersion of the present invention, boron nitride such as hexagonal boron nitride (h-BN) has a stronger interaction between layers than graphite, but is extremely difficult to peel off. As an example, when a superacid such as chlorosulfonic acid or fluorosulfonic acid is used and mixed treatment such as weak ultrasonic treatment is performed in such superacid, dispersion and peeling of boron nitride (BN) proceeds. . That is, a proton (H ⁺ ) of a superacid is bonded to a N atom of boron nitride (coordination bond (covalent bond) and / or non-bonded) in a space between layers of boron nitride slightly formed by mixing treatment such as ultrasonic treatment. (Covalent bond), re-aggregation of boron nitride is suppressed by repulsion of positive charges between layers of boron nitride and adsorption of superacid anion due to interaction between superacid anion and boron nitride. Separation can proceed sufficiently. In addition, when superacids (including superacid-derived compounds) are adsorbed on the surface of boron nitride, dispersibility (dispersion stability) in superacids and other solvents (water and various organic solvents) is improved. The present inventors infer that.

  According to the present invention, a boron nitride nanosheet-containing dispersion in which boron nitride nanosheets are highly dispersed in a superacid and a method for producing the same, a boron nitride nanosheet composite having excellent dispersibility in a solvent or in a resin, and a method for producing the same Can be provided.

  Hereinafter, the present invention will be described in detail with reference to preferred embodiments thereof.

  First, the boron nitride nanosheet-containing dispersion of the present invention will be described. The boron nitride nanosheet-containing dispersion of the present invention includes a superacid and a boron nitride nanosheet dispersed in the superacid. With such a boron nitride nanosheet-containing dispersion, a boron nitride nanosheet-containing dispersion in which boron nitride nanosheets are highly dispersed in a superacid can be obtained.

(Boron nitride nanosheet)
The boron nitride nanosheet used in the present invention is a sheet in a form in which a layer of boron nitride having a multilayer structure is peeled off. The boron nitride nanosheet used in the present invention is not particularly limited, and specifically, boron nitride nanosheets, boron carbonitride (B—C—N material) nanosheets, and nitriding as ribbon-like materials of these sheets Examples of boron nanoribbons, boron carbonitride nanoribbons, and scrolls of the sheet include boron nitride nanoscrolls and boron carbonitride nanoscrolls. Among these, boron nitride nanosheets are more preferable from the viewpoint of sufficiently expressing insulation, heat resistance, oxidation resistance, and the like.

  The thickness of the boron nitride nanosheet of the present invention is not particularly limited, but preferably includes a boron nitride nanosheet of 20 nm or less, and more preferably includes a boron nitride nanosheet of 10 nm or less. It is more preferable that boron nitride nanosheets of 5 nm or less are included, particularly preferable that boron nitride nanosheets of 2 nm or less are included, and that boron nitride nanosheets of 1 nm or less be included. Most preferred. When the thickness of the boron nitride nanosheet exceeds the upper limit, the effect of improving the thermal conductivity and the like of the boron nitride nanosheet composite comprising the boron nitride nanosheet of the present invention and the resin composition containing the same tends to decrease.

  In the present invention, the thickness of the boron nitride nanosheet is measured by extracting 25 arbitrary locations in a size of 35 nm × 35 nm as locations where the edge of the boron nitride nanosheet can be confirmed in a transmission electron micrograph. The average of these measured values.

  Further, the number of layers of the boron nitride nanosheet of the present invention is not particularly limited, but the specific surface area of the boron nitride nanosheet is increased, and the boron nitride nanosheet composite obtained using the boron nitride nanosheet-containing dispersion of the present invention is used. From the viewpoint of improving the thermal conductivity of the body and the resin composition containing the same, it is preferable to contain 50 or less layers of boron nitride nanosheets, more preferably 30 layers or less of boron nitride nanosheets, and more preferably 10 layers or less. It is more preferable that it contains a boron nitride nanosheet of 6 layers or less, particularly preferably include a boron nitride nanosheet of 6 layers or less, particularly preferably include a boron nitride nanosheet of 2 layers or less, and include a single-layer boron nitride nanosheet. Most preferably.

  Furthermore, in such a boron nitride nanosheet of the present invention, the abundance ratio of 10 or less layers of boron nitride nanosheet is not particularly limited, but is preferably 50% or more, more preferably 60% or more, It is more preferably 70% or more, particularly preferably 80% or more, and most preferably 90% or more. In the boron nitride nanosheet, when the proportion of boron nitride nanosheets of 10 layers or less is less than the lower limit, a boron nitride nanosheet composite obtained using the boron nitride nanosheet-containing dispersion of the present invention, a resin composition containing the same, and the like There exists a tendency for the improvement effects, such as thermal conductivity (thermal conductivity), to fall.

  Further, in the boron nitride nanosheet of the present invention, the abundance ratio of the boron nitride nanosheet having 6 layers or less is not particularly limited, but is preferably 10% or more, more preferably 20% or more, It is more preferably 30% or more, particularly preferably 40% or more, and most preferably 50% or more. In the boron nitride nanosheet, the boron nitride nanosheet composite obtained using the boron nitride nanosheet-containing dispersion of the present invention when the proportion of boron nitride nanosheets of 6 layers or less is less than the lower limit, a resin composition containing the same, and the like There exists a tendency for the improvement effects, such as thermal conductivity (thermal conductivity), to fall.

  Furthermore, in such a boron nitride nanosheet of the present invention, the abundance ratio of the boron nitride nanosheet having three or less layers is not particularly limited, but is preferably 4% or more, more preferably 5% or more, It is more preferably 10% or more, particularly preferably 15% or more, and most preferably 20% or more. In the boron nitride nanosheet, the boron nitride nanosheet composite obtained using the boron nitride nanosheet-containing dispersion of the present invention and the resin composition including the boron nitride nanosheet-containing dispersion of the present invention when the proportion of boron nitride nanosheets of three layers or less is less than the lower limit Improvement effects such as thermal conductivity (thermal conductivity) tend to decrease.

  Further, in such a boron nitride nanosheet of the present invention, the proportion of boron nitride nanosheets having two or less layers is not particularly limited, but is preferably 4% or more, more preferably 5% or more, It is more preferably 10% or more, particularly preferably 15% or more, and most preferably 20% or more. In the boron nitride nanosheet, when the proportion of boron nitride nanosheets of two layers or less is less than the lower limit, a boron nitride nanosheet composite obtained using the boron nitride nanosheet-containing dispersion of the present invention, a resin composition containing the same, and the like There exists a tendency for the improvement effects, such as thermal conductivity (thermal conductivity), to fall.

  Furthermore, in such a boron nitride nanosheet of the present invention, the presence ratio of the boron nitride nanosheet having a single layer structure is not particularly limited, but is preferably 4% or more, more preferably 5% or more, It is further preferably 8% or more, particularly preferably 10% or more, and most preferably 20% or more. In the boron nitride nanosheet, when the existing ratio of the boron nitride nanosheet having a single layer structure is less than the lower limit, the boron nitride nanosheet composite obtained using the boron nitride nanosheet-containing dispersion of the present invention, a resin composition including the same, and the like There exists a tendency for the improvement effects, such as thermal conductivity (thermal conductivity), to fall.

  Moreover, in such a boron nitride nanosheet of the present invention, the lower limit of the length of one side of the boron nitride nanosheet is not particularly limited, but the viewpoint of improving the thermal conductivity of the obtained boron nitride nanosheet composite or resin composite Therefore, it is preferably 0.001 μm or more, more preferably 0.01 μm or more, further preferably 0.1 μm or more, particularly preferably 0.5 μm or more, and 1 μm or more. Is most preferred. In the boron nitride nanosheet, when the length of one side of the boron nitride nanosheet is less than the lower limit, the boron nitride nanosheet composite obtained using the boron nitride nanosheet-containing dispersion of the present invention and the heat of the resin composition including the same Improvement effects such as conductivity (thermal conductivity) tend to decrease. In the prior art, dispersion of a boron nitride nanosheet having a large side length, for example, having a side length of 1 μm or more tends to be difficult compared with a boron nitride nanosheet having a side length of less than 1 μm. When the superacid of the invention is used, the dispersibility of the boron nitride nanosheet having a large side length tends to be greatly improved.

(Super acid)
Superacids for use in the present invention is less than Hammett acidity function at 25 ° C. (H ₀₎ -12 (i.e., more negative) an acid having acidity function (H _0). Here, Hammett's acidity function (H ₀ ) is generally used as an index of acidity, and is a value inherent to the type, composition, and concentration of superacid and acid, and varies with temperature (LOUIS P. HAMMETTT). Et al., J. Am. Chem. Soc., 54, 1932, page 2721). The H ₀ of various superacids at 25 ° C. is described in detail in, for example, the Basic Guide to Chemical Handbook (5th revised edition, edited by the Chemical Society of Japan) (Tables 11.47 and 11 of the Handbook II). .51, Table 11.52, Table 11.53, etc.).

As such a superacid used in the present invention, the upper limit of the acidity function (H ₀ ) is less than −12.5 from the viewpoint of the amount of adsorption to the boron nitride nanosheet and / or the peelability of the boron nitride nanosheet. Is preferable, and less than −13 is more preferable. In addition, the lower limit of the acidity function (H ₀ ) is preferably −60 or more, more preferably −30 or more, and −25 or more from the viewpoint of dispersibility of the obtained boron nitride nanosheet composite. Is more preferable, and it is particularly preferably -20 or more.

Specific examples of the superacid used in the present invention include chlorosulfonic acid (chlorosulfonic acid, HSO ₃ Cl), fluorosulfonic acid (FSO ₃ H), hydrofluoric acid (HF), trifluoro. b methanesulfonic acid _(CF 3 _SO 3 H), pentafluoroethane sulfonic acid _{(C 2 HF 5 O 3 S} ), tetrafluoroboric acid _(HBF 4), hexafluorophosphate, chloride, boron fluoride acid, pentafluoride Mixture of antimony and fluorosulfonic acid, mixture of antimony pentafluoride and hydrofluoric acid, antimony hexafluoride, arsenic hexafluoride, carborane acid, fluorinated carborane acid, difluoromethane disulfonic acid, tetrafluoroethane Disulfonic acid, hexafluoropropane disulfonic acid, disulfuric acid, trifluoroethane trisulfonic acid, penta Examples include fluoropropanetrisulfonic acid, heptafluorobutanetrisulfonic acid, hexafluorobutanetetrasulfonic acid, octafluoropentanetetrasulfonic acid, decafluorohexanetetrasulfonic acid, and their salts and derivatives. These may be used alone or in combination of two or more. Among these super acids, chlorosulfonic acid, fluorosulfonic acid, trifluoromethanesulfonic acid, tetrafluorosulfonic acid, tetrafluoromethanesulfonic acid, tetrafluoromethanesulfonic acid, tetrafluoromethanesulfonic acid, tetrafluoromethanesulfonic acid, tetrafluoromethanesulfonic acid, tetrafluoromethanesulfonic acid, tetrafluorosulfonic acid It is preferably at least one selected from the group consisting of fluoroboric acid, more preferably chlorosulfonic acid and / or fluorosulfonic acid, which is a sulfonic acid in which halogen is directly bonded to an S atom, It is particularly preferred. In the present invention, a mixture of the superacid and an acid other than the superacid can also be used.

(Boron nitride nanosheet-containing dispersion)
The boron nitride nanosheet-containing dispersion of the present invention includes the superacid and the boron nitride nanosheet dispersed in the superacid.

  In such a boron nitride nanosheet-containing dispersion of the present invention, the concentration of the boron nitride nanosheet to be contained is not particularly limited, but from the viewpoint of more preferably expressing characteristics such as thermal conductivity of the boron nitride nanosheet, 0. 0.01 mg / mL or more is preferable, 0.1 mg / mL or more is more preferable, 0.2 mg / mL or more is further preferable, and 0.5 mg / mL or more is particularly preferable.

  In the boron nitride nanosheet-containing dispersion of the present invention, it is preferable that at least a part of the superacid is adsorbed on the boron nitride nanosheet. By doing in this way, it exists in the tendency which can exfoliate boron nitride efficiently, and can obtain the dispersion liquid containing a boron nitride nanosheet with few layers at higher concentration.

  Furthermore, in the boron nitride nanosheet-containing dispersion of the present invention and the boron nitride nanosheet composite-containing dispersion of the present invention described later, various fillers can be further added and used. Examples of such fillers include, but are not limited to, alumina, aluminum nitride, cubic boron nitride, silicon nitride, silicon carbide, carbon nitride, diamond, zinc oxide, graphite, carbon fiber, carbon nanofiber, carbon Carbon-based nanofillers such as nanotubes, carbon nanoplatelets, graphene, several-layer graphene, nanographite (graphene nanoribbons, etc.), nanographene, carbon nanohorns, carbon nanocones, carbon nanocoils, fullerenes, transition metal dichalcogenides, group 13 Chalcogenide-based layered materials such as chalcogenides, group 14 chalcogenides and bismuth chalcogenides, layered high-temperature superconducting compounds, layered silicates such as mica, talc, and kaolin, titanium oxide-based and perovs Layered oxides such as site-based nanosheets can be mentioned as preferred. Among these, for example, when a layered material such as graphite, several-layer graphene, hexagonal silicon nitride, hexagonal silicon carbide and chalcogenide layered material and boron nitride or boron nitride nanosheet are mixed in a superacid, these materials It is also possible to obtain a dispersion liquid in which peeling or dispersion of the resin has progressed. Moreover, the solvent was removed from the dispersion of these mixtures, and the nanosheets obtained by exfoliating the layered material and the boron nitride nanosheets or boron nitride nanosheet composites were oriented and arranged to obtain the layered material by exfoliation. A laminate comprising a nanosheet and a boron nitride nanosheet or a boron nitride nanosheet composite can also be produced.

  In the boron nitride nanosheet-containing dispersion of the present invention, the color tone of the dispersion is not particularly limited, but tends to be different depending on the combination of boron nitride species and superacid species, white, pale yellow, yellow, pale Indicates orange or orange. The reason why the boron nitride nanosheet-containing dispersion of the present invention and the filtrate after obtaining the boron nitride nanosheet composite by filtration described later is light orange or orange is not clear, but the proton of superacid is nitrided When bonded to the surface of the boron nanosheet (coordination bond (covalent bond) and / or non-covalent bond), a counter anion of superacid (for example, sulfonate anion in the case of chlorosulfonic acid) and the boron nitride nanosheet The anion-π interaction and the charge transfer interaction between the superacid and boron nitride are involved in the coloration, and the superacid proton is bonded to the nitrogen atom of the boron nitride nanosheet (covalent bond and / or non-bonding). It is inferred that some anionic species in the superacid are liberated due to (covalent bond) and are involved in coloration.

[Production method of boron nitride nanosheet-containing dispersion]
Next, the manufacturing method of the boron nitride nanosheet containing dispersion liquid of this invention is demonstrated. In the method for producing a boron nitride nanosheet composite of the present invention, boron nitride and a superacid are mixed (mixing treatment), and the boron nitride nanosheet is obtained by separating layers of the boron nitride, and the superacid and the superacid. A boron nitride nanosheet-containing dispersion liquid comprising a boron nitride nanosheet dispersed in the process is obtained. In the method for producing a dispersion containing boron nitride nanosheets of the present invention, boron nitride is peeled off by mixing the boron nitride in the presence of superacid, and boron nitride nanosheets are highly dispersed in the superacid. A dispersion having excellent dispersibility can be obtained. As the boron nitride nanosheet and the superacid, the boron nitride nanosheet and the superacid described in the boron nitride nanosheet-containing dispersion of the present invention can be used.

(Boron nitride)
In such a method for producing a boron nitride nanosheet-containing dispersion of the present invention, boron nitride used as a raw material includes hexagonal boron nitride (h-BN), rhombohedral boron nitride (r-BN), and a disordered layer. There is no particular limitation as long as it is a boron nitride containing layered boron nitride such as structural boron nitride (t-BN), but the thermal conductivity of a boron nitride nanosheet composite obtained using such a boron nitride nanosheet-containing dispersion liquid From the viewpoints of insulation and heat resistance, boron nitride containing hexagonal boron nitride is particularly preferable. The shape of such boron nitride is not particularly limited, but various types of boron nitride such as powder, flakes and beads can be used. In addition, as such boron nitride, boron carbonitride (B—C—N material) containing carbon atoms as an analog of boron nitride, or boron nitride surface-treated with a silane coupling agent or the like can be used. However, it suppresses the increase in defects caused by the formation of the covalent bond between the superacid and the boron nitride nanosheet, from the viewpoint of sufficiently expressing the thermal conductivity, insulation, heat resistance, oxidation resistance, etc. of the boron nitride nanosheet. From the viewpoint, boron nitride having a high BN purity is more preferable. The purity of BN of the boron nitride of the present invention is not particularly limited, but the obtained boron nitride nanosheet composite, the boron nitride nanosheet-containing dispersion, the resin composition comprising the boron nitride nanosheet composite, the heat of the boron nitride nanosheet laminate From the viewpoint of improving conductivity and oxidation resistance, it is preferably 80% by mass or more, more preferably 90% by mass or more, still more preferably 95% by mass or more, and 97% by mass or more. Particularly preferred is 99% by mass or more. The BN purity of boron nitride can be determined using an inert gas melting thermal conductivity method.

  The average secondary particle diameter of boron nitride used as a raw material is not particularly limited, but in the method for producing a boron nitride nanosheet-containing dispersion of the present invention, it is usually an average that is difficult to separate and disperse by using a superacid. Boron nitride having a large secondary particle size can also be dispersed. The lower limit of the average secondary particle diameter of boron nitride used as a raw material is not particularly limited, but is preferably 0.01 μm or more, more preferably 0.1 μm or more, and further preferably 0.2 μm or more. Preferably, it is particularly preferably 0.3 μm or more, and most preferably 0.4 μm or more. Further, the lower limit of the average size of one side of the boron nitride primary particles constituting the boron nitride secondary particles used as a raw material is not particularly limited, but is preferably 0.01 μm or more, and more preferably 0.05 μm or more. Is more preferably 0.1 μm or more, particularly preferably 0.2 μm or more, and most preferably 0.3 μm or more.

(Mixing / mixing process)
In the method for producing a dispersion containing boron nitride nanosheets of the present invention, the boron nitride and the superacid are mixed, the layers of the boron nitride are separated to obtain a boron nitride nanosheet, and the superacid and the superacid are mixed. It is necessary to obtain a boron nitride nanosheet-containing dispersion comprising boron nitride nanosheets that are dispersed.

  The mixing treatment of the present invention is not particularly limited, but at least one selected from ultrasonic treatment, vibration treatment, stirring treatment, pulverization treatment, external field application (for example, electric field application, magnetic field application, etc.), and kneading. It is preferable that the mixing process. Among these mixing treatments, the mixing (mixing treatment) includes at least one delamination treatment selected from the group consisting of ultrasonic treatment, stirring treatment and grinding treatment on the boron nitride in the presence of the superacid. It is more preferable that the mixing process includes a step of applying. By this delamination process, the boron nitride exfoliation efficiently proceeds, and a boron nitride nanosheet composite containing boron nitride nanosheets with a small number of layers tends to be obtained. In addition, as such mixing (mixing process), it is especially preferable that it is ultrasonic processing.

  Further, in the method for producing the boron nitride nanosheet-containing dispersion of the present invention, various fillers can be further added and used as described in the boron nitride nanosheet-containing dispersion. Among these various fillers, for example, layered materials such as graphite, several-layer graphene, hexagonal silicon nitride, hexagonal silicon carbide, and chalcogenide-based layered materials and boron nitride or boron nitride nanosheets in superacids. When mixed, it is possible to obtain a dispersion in which peeling or dispersion of these substances has proceeded. Moreover, the solvent was removed from the dispersion of these mixtures, and the nanosheets obtained by exfoliating the layered material and the boron nitride nanosheets or boron nitride nanosheet composites were oriented and arranged to obtain the layered material by exfoliation. A laminate comprising a nanosheet and a boron nitride nanosheet or a boron nitride nanosheet composite can be produced.

[Boron nitride nanosheet composite]
Next, the boron nitride nanosheet composite of the present invention will be described. The boron nitride nanosheet composite of the present invention comprises the boron nitride nanosheet and the superacid adsorbed on the boron nitride nanosheet.

  In the boron nitride nanosheet composite of the present invention, the boron nitride nanosheet and superacid described in the boron nitride nanosheet-containing dispersion of the present invention can be used as the boron nitride nanosheet and superacid. The superacid used in the boron nitride nanosheet composite of the present invention may contain a superacid-derived compound. As the superacid-derived compound, for example, when chlorosulfonic acid is used as the superacid, at least part of the chlorosulfonic acid adsorbed on the surface of the boron nitride nanosheet or between the layers reacts with water. Mention may be made of sulfuric acid. Hydrogen chloride produced by the reaction of chlorosulfonic acid adsorbed on the boron nitride nanosheet composite with water has a low boiling point and is usually volatilized as a gas. However, at least one of the hydrochloric acid produced by mixing hydrogen chloride with water is at least one. Part may be adsorbed on the boron nitride nanosheet surface or between layers as a superacid-derived compound together with sulfuric acid or chlorosulfonic acid. The amount of the superacid-derived compound contained in the superacid used in the boron nitride nanosheet composite of the present invention is not particularly limited, but in other solvents other than the superacid of the boron nitride nanosheet composite. From the viewpoint of improving dispersibility, it is preferably 90% by mass or less, more preferably 80% by mass or less, and more preferably 70% by mass or less, out of 100% by mass of superacid (including a superacid-derived compound). More preferably, it is particularly preferably 50% by mass or less.

In the boron nitride nanosheet composite of the present invention, the adsorption of the boron nitride nanosheet and the superacid may be adsorption by non-covalent bond or by covalent bond (including coordination bond). In addition, it may be a combination of these, but at least a part of the adsorption is preferably adsorption by non-covalent bond from the viewpoint of improving the thermal conductivity of the boron nitride nanosheet composite, Particularly preferred is a non-covalent bond. In the present invention, by coexisting superacid with boron nitride nanosheets, cation-π interaction (non-covalent bond) between proton (H ⁺ ) constituting superacid and nitrogen atom of boron nitride and / or superacid Bonds of the protons constituting the boron nitride to the nitrogen atom (coordination bond (covalent bond) and / or non-covalent bond) occur, and the anion-π interaction between the anion constituting the superacid and the boron nitride, Non-covalent bonds such as charge transfer interactions and van der Waals forces between superacids and boron nitride also occur. In addition, when the boron nitride nanosheet composite is repeatedly washed with a large amount of water, part or all of the coordination bond formed between the proton of the superacid and the nitrogen atom of the boron nitride nanosheet is removed, and the superacid (superacid Boron nitride nanosheets that may be adsorbed only by non-covalent bonds between anions constituting superacids and boron nitride nanosheets may be obtained. Thus, the boron nitride nanosheet composite in which a superacid (which may include a superacid-derived compound) is adsorbed to the boron nitride nanosheet by a non-covalent bond is boron nitride compared to the boron nitride nanosheet composite adsorbed by a covalent bond. Since the surface of the nanosheet has few or no defects and the characteristics inherent to the boron nitride nanosheet can be expressed, it is preferable from the viewpoint of improving the thermal conductivity of the boron nitride nanosheet composite, the dispersion liquid containing the same, and the resin composition .

  In the present invention, “adsorption by non-covalent bond” means adsorption by an interaction other than the covalent bond generated between the boron nitride nanosheet and the superacid. Examples of such non-covalent adsorption include cation-π interaction generated between the boron nitride nanosheet and the proton of the superacid, and anion generated between the boron nitride nanosheet and the anion of the superacid. Examples include those utilizing at least one type of interaction such as -π interaction, charge transfer interaction between the superacid and the boron nitride, and van der Waals force. Such adsorption of superacid to the boron nitride nanosheet is performed even when the boron nitride nanosheet composite is dispersed in another solvent other than superacid or when the boron nitride nanosheet composite is washed and filtered with the solvent. It is preferable that it remains in the nanosheet composite. Although the reason why the superacid is not eliminated by washing or the like is not necessarily clear even if it is adsorption by noncovalent bond, in the boron nitride nanosheet composite of the present invention, cation-π interaction, anion-π interaction This is probably because the interaction such as the charge transfer interaction and van der Waals force is working strongly.

  Further, in the present invention, “adsorption by covalent bond” is not particularly limited as long as the boron nitride nanosheet and the superacid are adsorbed via a covalent bond. For example, the plane or end of the boron nitride nanosheet In the case where a small amount of residual carbon atom, nitrogen atom, etc. present in the proton is protonated by a proton of a superacid, there may be mentioned. Further, in the structure of the boron nitride nanosheet, a substituent such as a carboxyl group, a nitro group, an amino group, an alkyl group, an organic silyl group, a polymer such as poly (meth) acrylate, polyaniline, polypyrrole, polyacetylene, poly ( Paraphenylene), conductive polymers such as polythiophene or polyphenylene vinylene, etc. introduced by chemical bonding, boron nitride nanosheets coated with other nanostructures such as metal nanoparticles and carbon-based nanofillers may also be used. it can.

  Such adsorption of the boron nitride nanosheet and the superacid is performed even when the boron nitride nanosheet composite is redispersed in a good solvent for the superacid, or when the boron nitride nanosheet composite is washed and filtered with the good solvent. It is preferable that it remains in the boron nitride nanosheet composite.

  In such a boron nitride nanosheet composite of the present invention, the adsorption amount of the superacid is not particularly limited, but from the viewpoint of improving dispersibility and fluidity (molding processability) of the boron nitride nanosheet composite. 0.01 mass part or more is preferable with respect to 100 mass parts of boron nanosheets, 0.1 mass part or more is more preferable, 0.3 mass part or more is still more preferable, 0.4 mass part or more is especially preferable, 0.5 The part by mass or more is most preferable. When the amount of superacid adsorbed is less than the lower limit, the dispersibility and fluidity (molding processability) of the boron nitride nanosheets tend to decrease. Further, the adsorption amount of the super acid is preferably 100000 parts by mass or less, more preferably 10,000 parts by mass or less with respect to 100 parts by mass of the boron nitride nanosheet, and the rigidity of the resin composition or resin composite containing the boron nitride nanosheet composite. From the viewpoint of improving adsorption stability, it is more preferably 1000 parts by mass or less, particularly preferably 100 parts by mass or less, and most preferably 90 parts by mass or less. In addition, about the adsorption amount of the super acid to a boron nitride nanosheet, it can calculate by calculating | requiring the weight reduction derived from a super acid by a thermogravimetric analysis.

  Further, the adsorption of the superacid on the boron nitride nanosheet surface can be confirmed by the above-described thermogravimetric analysis or X-ray photoelectron spectroscopic analysis. Specifically, when chlorosulfonic acid is used as the super acid, the Cl2p peak and S2p peak of chlorosulfonic acid can be confirmed by X-ray photoelectron spectroscopy, and the boron nitride nanosheet composite by X-ray photoelectron spectroscopy can be confirmed. The presence of Cl and S atoms can also be confirmed by surface elemental analysis.

  Further, the number of layers of boron nitride nanosheets contained in the boron nitride nanosheet composite is not particularly limited, but from the viewpoint of improving the thermal conductivity of the boron nitride nanosheet composite, the boron nitride nanosheet composite contains 50 or less boron nitride nanosheets. More preferably, it contains 30 or less layers of boron nitride nanosheets, more preferably contains 10 layers or less of boron nitride nanosheets, and particularly preferably contains 6 layers or less of boron nitride nanosheets. It is particularly preferable that it contains a boron nitride nanosheet of a layer or less, and most preferable that it contains a single layer of boron nitride nanosheet.

  Further, in the boron nitride nanosheet of the boron nitride nanosheet composite of the present invention, the proportion of the boron nitride nanosheet having 10 layers or less is not particularly limited, but is preferably 50% or more, preferably 60% or more. More preferably, it is more preferably 70% or more, particularly preferably 80% or more, and most preferably 90% or more. Further, in the boron nitride nanosheet of the boron nitride nanosheet composite of the present invention, the proportion of boron nitride nanosheets having 6 layers or less is not particularly limited, but is preferably 10% or more, and preferably 20% or more. More preferably, it is more preferably 30% or more, particularly preferably 40% or more, and most preferably 50% or more. Further, in the boron nitride nanosheet of the boron nitride nanosheet composite of the present invention, the proportion of boron nitride nanosheets having three or less layers is not particularly limited, but is preferably 4% or more, and preferably 5% or more. More preferably, it is more preferably 10% or more, particularly preferably 15% or more, and most preferably 20% or more. Further, in the boron nitride nanosheet of the boron nitride nanosheet composite of the present invention, the proportion of boron nitride nanosheets having two or less layers is not particularly limited, but is preferably 4% or more, preferably 5% or more. More preferably, it is more preferably 10% or more, particularly preferably 15% or more, and most preferably 20% or more. Further, in the boron nitride nanosheet of the boron nitride nanosheet composite of the present invention, the proportion of the single layer boron nitride nanosheet is not particularly limited, but is preferably 4% or more, and preferably 5% or more. More preferably, it is more preferably 8% or more, particularly preferably 10% or more, and most preferably 20% or more.

[Boron nitride nanosheet composite-containing dispersion]
Next, the boron nitride nanosheet composite-containing dispersion of the present invention will be described. The boron nitride nanosheet composite-containing dispersion of the present invention contains the boron nitride nanosheet composite of the present invention and a solvent other than superacid. The boron nitride nanosheet, superacid, and boron nitride nanosheet composite are the boron nitride nanosheet-containing dispersion of the present invention and the manufacturing method thereof, the boron nitride nanosheet described in the boron nitride nanosheet composite, superacid, and boron nitride nanosheet composite. The body can be used.

  In such a boron nitride nanosheet composite-containing dispersion of the present invention, the concentration of the boron nitride nanosheet composite to be contained is not particularly limited, but more preferably expresses characteristics such as thermal conductivity of the boron nitride nanosheet. From the viewpoint, it is preferably 0.01 mg / mL or more, more preferably 0.05 mg / mL or more, further preferably 0.1 mg / mL or more, and 0.2 mg / mL or more. Is particularly preferred.

  Further, the number of layers of boron nitride nanosheets contained in the boron nitride nanosheet composite-containing dispersion is not particularly limited. However, from the viewpoint of improving the thermal conductivity of the boron nitride nanosheet-containing dispersion, 50 or less layers of boron nitride Preferably it contains nanosheets, more preferably contains boron nitride nanosheets of 30 layers or less, more preferably contains boron nitride nanosheets of 10 layers or less, and contains boron nitride nanosheets of 6 layers or less. Particularly preferred are those containing two or less layers of boron nitride nanosheets, and most preferred are those containing a single layer of boron nitride nanosheets.

  Further, in the boron nitride nanosheet of the boron nitride nanosheet composite-containing dispersion of the present invention, the abundance ratio of 10 or less boron nitride nanosheets is not particularly limited, but is preferably 50% or more, % Or more, more preferably 70% or more, particularly preferably 80% or more, and most preferably 90% or more. Further, in the boron nitride nanosheet of the boron nitride nanosheet composite-containing dispersion of the present invention, the presence ratio of boron nitride nanosheets of 6 layers or less is not particularly limited, but is preferably 10% or more, % Or more, more preferably 30% or more, particularly preferably 40% or more, and most preferably 50% or more. Furthermore, in the boron nitride nanosheet of such a boron nitride nanosheet composite-containing dispersion of the present invention, the proportion of boron nitride nanosheets having three or less layers is not particularly limited, but is preferably 4% or more. % Or more, more preferably 10% or more, particularly preferably 15% or more, and most preferably 20% or more. Further, in the boron nitride nanosheet of the boron nitride nanosheet composite-containing dispersion of the present invention as described above, the proportion of boron nitride nanosheets having two or less layers is not particularly limited, but is preferably 4% or more. % Or more, more preferably 10% or more, particularly preferably 15% or more, and most preferably 20% or more. Further, in the boron nitride nanosheet of the boron nitride nanosheet composite-containing dispersion of the present invention, the presence ratio of the single layer boron nitride nanosheet is not particularly limited, but is preferably 4% or more, and 5% More preferably, it is more preferably 8% or more, particularly preferably 10% or more, and most preferably 20% or more.

(Solvents other than super acids)
In the boron nitride nanosheet composite-containing dispersion of the present invention, the solvent other than the superacid is not particularly limited, and examples thereof include an organic solvent and water. These may be used alone or in combination. Also good. Examples of the organic solvent include chloroform, dichloromethane, carbon tetrachloride, acetone, methyl ethyl ketone, methyl isobutyl ketone, diisobutyl ketone, methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate, isobutyl acetate, pentyl acetate, and isopentyl acetate. , Amyl acetate, tetrahydrofuran, N-methyl-2-pyrrolidone, dimethylformaldehyde, dimethylacetamide, dimethyl sulfoxide, acetonitrile, methanol, ethanol, propanol, isopropanol, butanol, hexanol, octanol, hexafluoroisopropanol, ethylene glycol, propylene glycol, tetra Methylene glycol, tetraethylene glycol, hexamethylene glycol, diethylene Recall, benzene, toluene, xylene, chlorobenzene, dichlorobenzene, trichlorobenzene, chlorophenol, phenol, tetrahydrofuran, sulfolane, 1,3-dimethyl-2-imidazolidinone, γ-butyrolactone, 1,5-dimethyl-2-pyrrolidone , Pentane, hexane, neopentane, cyclohexane, heptane, octane, isooctane, nonane, decane, diethyl ether and the like. These organic solvents may be used alone or in combination of two or more.

  In the solvent in the dispersion containing the boron nitride nanosheet composite of the present invention, as the organic solvent, the boron acid nanosheet composite of the present invention and the superacid used in the production thereof, particularly the anion species constituting the superacid, and Those having high affinity are preferable, for example, N-methyl-2-pyrrolidone, dimethylformaldehyde, dimethylacetamide, dimethylsulfoxide, acetonitrile, hexafluoroisopropanol, 1,3-dimethyl-2-imidazolidinone, γ-butyrolactone, 1 , 5-dimethyl-2-pyrrolidone, methanol, ethanol, propanol, isopropanol, butanol, hexanol, octanol, hexafluoroisopropanol, ethylene glycol, propylene glycol, tetramethylene glycol, tetra Ji glycol, hexamethylene glycol, and preferably diethylene glycol. Further, in such a boron nitride nanosheet composite-containing dispersion of the present invention, a vinyl monomer such as styrene and (meth) acrylic acid, a main component of a cured resin such as an epoxy resin, and a raw material such as a crosslinking agent are also used as a solvent. The boron nitride nanosheet composite is dispersed in these solvents and polymerized to obtain a resin composite in which the boron nitride nanosheet composite is highly dispersed.

(Production of dispersion containing boron nitride nanosheet composite)
In the boron nitride nanosheet composite-containing dispersion of the present invention, the boron nitride nanosheet composite of the present invention can be prepared in the superacid and used as a dispersion as it is, but the boron nitride nanosheet composite of the present invention can be used as it is. Since the body is excellent in redispersibility in a solvent other than a superacid, the boron nitride nanosheet composite of the present invention is added to a solvent other than a superacid and subjected to ultrasonic treatment or the like, and then mixed. The boron nitride nanosheet composite-containing dispersion of the present invention can be produced. Moreover, boron nitride or a boron nitride nanosheet, a super acid and a solvent other than the super acid may be mixed or mixed separately to produce a boron nitride nanosheet composite-containing dispersion. Further, when manufacturing by mixing all at once, super acid is adsorbed to boron nitride in a solvent other than super acid, boron nitride is peeled off, boron nitride nanosheet composite is formed, and boron nitride nanosheet composite-containing dispersion is prepared. Can be obtained.

  The mixing method is not particularly limited, but is at least one kind of mixing treatment selected from ultrasonic treatment, vibration treatment, stirring treatment, pulverization treatment, external field application (for example, electric field application, magnetic field application, etc.), and kneading. It is preferable. Among these methods, the boron nitride nanosheet having a small number of layers can be efficiently promoted to remove boron nitride by being at least one mixed treatment selected from the group consisting of ultrasonic treatment, stirring treatment and pulverization treatment. It is more preferable to obtain a dispersion containing a higher concentration. In addition, from the viewpoint of obtaining a dispersion having a higher dispersion stability and a higher concentration, ultrasonic treatment is more preferable among these mixing treatments. In addition, ultrasonic treatment using an ultrasonic cleaner is particularly preferable in the mixing treatment from the viewpoint of highly dispersing while suppressing damage to the boron nitride nanosheet.

  Further, in the method for producing a dispersion containing boron nitride nanosheet composite of the present invention, after the mixing (mixing process), a large amount present in the dispersion by centrifugation and / or standing. It is preferable to remove boron nitride particles that are difficult to separate due to particles or physical entanglement. In addition, in the case of centrifugation operation and / or standing, it is preferable to carry out in inert gas atmosphere from a viewpoint of obtaining a high concentration dispersion liquid, and a viewpoint of handling safety. Further, from the viewpoint of improving the handleability of the dispersion, it is preferable to exchange the solvent from a superacid to another solvent (an organic solvent or water). Moreover, after exchanging the solvent with another solvent, removing boron nitride particles that are difficult to peel off due to large particles or physical entanglement present in the dispersion by centrifugation and / or standing still, This is preferable from the viewpoint of obtaining a boron nitride nanosheet composite having a small number of layers and a dispersion containing the same.

[Method for producing boron nitride nanosheet composite]
Next, a method for producing the boron nitride nanosheet composite of the present invention will be described. A method for producing a boron nitride nanosheet composite of the present invention is a method for producing a boron nitride nanosheet composite comprising a boron nitride nanosheet and a superacid adsorbed on the boron nitride nanosheet, wherein the boron nitride and the superacid are combined. It is a method characterized by mixing, peeling between the layers of boron nitride to obtain boron nitride nanosheets, and adsorbing superacid on the boron nitride nanosheets. As the boron nitride nanosheet and the superacid, the boron nitride nanosheet and the superacid described in the boron nitride nanosheet-containing dispersion and boron nitride nanosheet composite of the present invention can be used.

As a method for producing such a boron nitride nanosheet composite of the present invention, except for including the mixing treatment (mixing), the boron nitride nanosheet is obtained by separating the layers of the boron nitride, and the superposition of the boron nitride nanosheet is performed on the boron nitride nanosheet. The method is not particularly limited as long as it is a method capable of adsorbing an acid, and examples thereof include the following methods.
(I) A method of performing delamination treatment by mixing the boron nitride and the superacid without using a solvent.
(Ii) A method of performing delamination treatment by mixing the boron nitride and the superacid in a solvent.
(Iii) A method of mixing the boron nitride nanosheet and the superacid without using a solvent.
(IV) A method of mixing the boron nitride nanosheet and the superacid in a solvent.

  These manufacturing methods may be carried out alone or in combination of two or more.

(Boron nitride)
In such a method for producing a boron nitride nanosheet composite of the present invention, boron nitride used as a raw material includes hexagonal boron nitride (h-BN), rhombohedral boron nitride (r-BN), and a layered structure. There is no particular limitation as long as it is boron nitride containing layered boron nitride such as boron nitride (t-BN), but hexagonal crystal is particularly preferable from the viewpoint of thermal conductivity, insulation, and heat resistance of the obtained boron nitride nanosheet composite. Boron nitride containing boron nitride. The shape of such boron nitride is not particularly limited, but various types of boron nitride such as powder, flakes and beads can be used. In addition, as such boron nitride, boron carbonitride (B—C—N material) containing carbon atoms as an analog of boron nitride, or boron nitride surface-treated with a silane coupling agent or the like can be used. However, from the viewpoint of sufficiently expressing the thermal conductivity, insulating properties, heat resistance, oxidation resistance, and the like of the boron nitride nanosheet, boron nitride having a high BN purity is more preferable.

  The average secondary particle diameter of boron nitride used as a raw material is not particularly limited. However, in the method for producing a boron nitride nanosheet composite of the present invention, the average secondary particle size that is usually difficult to separate and disperse by using a superacid. Boron nitride having a large secondary particle size can also be dispersed. The lower limit of the average secondary particle diameter of boron nitride used as a raw material is not particularly limited, but is preferably 0.01 μm or more, more preferably 0.1 μm or more, and further preferably 0.2 μm or more. Preferably, it is particularly preferably 0.3 μm or more, and most preferably 0.4 μm or more. Further, the lower limit of the average size of one side of the boron nitride primary particles constituting the boron nitride secondary particles used as a raw material is not particularly limited, but is preferably 0.01 μm or more, and more preferably 0.05 μm or more. Is more preferably 0.1 μm or more, particularly preferably 0.2 μm or more, and most preferably 0.3 μm or more.

(Mixing / mixing process)
In the method for producing a boron nitride nanosheet composite of the present invention, the boron nitride and the superacid are mixed, the layers of the boron nitride are separated to obtain a boron nitride nanosheet, and the superacid is adsorbed on the boron nitride nanosheet. It is necessary to include a process.

  In such a method for producing a boron nitride nanosheet composite of the present invention, as the mixing (mixing process), ultrasonic treatment, vibration treatment, stirring treatment, pulverization treatment, external field application (for example, electric field application, magnetic field application) Preferably, a mixing process including a step of performing at least one delamination process selected from kneading. Among these mixing treatments, the mixing (mixing treatment) includes at least one delamination treatment selected from the group consisting of ultrasonic treatment, stirring treatment and grinding treatment on the boron nitride in the presence of the superacid. It is more preferable that the mixing process includes a step of applying. By this delamination process, the boron nitride exfoliation efficiently proceeds, and a boron nitride nanosheet composite containing boron nitride nanosheets with a small number of layers tends to be obtained. In addition, it is preferable that such mixing (mixing process) is performed in inert gas atmosphere from a viewpoint of the dispersibility of a boron nitride nanosheet, peelability, and handling safety.

  From the viewpoint of obtaining a boron nitride nanosheet composite having excellent dispersibility and redispersibility and a boron nitride nanosheet composite-containing dispersion having excellent dispersibility at a high concentration, as a step of performing such delamination treatment, ultrasonic treatment and More preferably, at least one selected from the group consisting of stirring treatments is carried out in an inert gas atmosphere, and ultrasonic treatment carried out in an inert gas atmosphere is particularly preferred. Such ultrasonic treatment is not particularly limited, and examples thereof include a method using an ultrasonic cleaner and a method using an ultrasonic homogenizer (probe type sonicator). However, damage to the surface of the boron nitride nanosheet is caused. From the viewpoint of suppressing and exhibiting the original characteristics of the boron nitride nanosheet, a method using an ultrasonic cleaner is particularly preferable. For example, in the above mixing processes (i) and (ii), when the dispersion solution is subjected to ultrasonic treatment after dispersing boron nitride in superacid, for example, using a tabletop ultrasonic cleaner, ultrasonic oscillation is performed. When the frequency is 45 kHz, the sonication time is not particularly limited, but is preferably 1 minute or more, more preferably 1 hour or more, still more preferably 5 hours or more, and particularly preferably 25. More than hours, most preferably more than 48 hours. In the prior art, when the sonication time is short, for example, when it is 1 minute or more and less than 1 hour, it is difficult to obtain the boron nitride nanosheet according to the present invention. The boron nitride can be efficiently peeled off, and the boron nitride nanosheet composite of the present invention and the boron nitride nanosheet composite-containing dispersion of the present invention can be obtained. In the prior art, when the ultrasonic treatment time exceeds about 24 hours, there is a problem that the hexagonal sheet structure is destroyed and the size is reduced, but in the present invention, by using superacid, Boron nitride particles having a large particle size can be used as a raw material, and since the peeling proceeds efficiently, the peeling can be further advanced while suppressing the destruction of the hexagonal sheet structure, yield. Can be further improved. In addition, the suppression of such hexagonal sheet structure destruction is because the superacid is adsorbed on the surface of the boron nitride nanosheet, the separation to the boron nitride nanosheet proceeds quickly, and reaggregation is suppressed, It is presumed that structural destruction due to direct contact between the boron nitride nanosheets in the secondary particles or close proximity under the ultrasonic treatment conditions is reduced, and the structural destruction of the hexagonal sheet structure can be suppressed.

  In addition, when performing a stirring process as such a mixing process (delamination process), the rotation speed of the stirring process is not particularly limited, but is preferably 100 rpm or more, more preferably 200 rpm or more, and still more preferably. 300 rpm or more, particularly preferably 400 rpm or more, and most preferably 500 rpm or more. When the rotational speed of the stirring treatment is less than the lower limit, the proportion of the boron nitride nanosheets having 10 layers or less tends to decrease, and the dispersibility of the nitrogen boron nanosheet composite tends to decrease.

  Further, when the pulverization process is performed as such a mixing process (delamination process), the pulverization process method is not particularly limited, but a mortar, shearing mill, jaw crusher, impact crusher, cone crusher, roll crusher A hammer mill, a ball mill, a vibration mill, a pin mill, a stirring mill, a dry jet mill, a pulverizing method using a wet jet mill, and the like can be used. In the case of producing a boron nitride nanosheet composite or boron nitride nanosheet composite in the presence of a superacid by such a pulverization treatment, the pulverization time is not particularly limited, but is preferably 5 minutes or more, More preferably, it is 30 minutes or more, more preferably 1 hour or more, particularly preferably 2 hours or more, and most preferably 3 hours or more. By crushing boron nitride in the presence of superacid, the shearing force applied to boron nitride and boron nitride nanosheets can be controlled appropriately, and peeling can proceed efficiently while suppressing breakage in the surface direction. be able to. In addition, in the absence of superacid, when directly pulverizing boron nitride or boron nitride nanosheets, the shear becomes too large compared to the case of pulverizing in the presence of superacid. There is a problem that the fracture in the surface direction occurs and the size of one side is reduced, and the boron nitride nanosheet and the boron nitride nanosheet composite of the present invention cannot be obtained.

  In the delamination process of the present invention, when melt kneading is performed, the boron nitride and the super acid, and if necessary, the resin and / or additive in pellets, powders or strips, respectively. Then, after uniformly mixing by a stirrer, a drive lender, hand mixing, or the like, it can be melt-kneaded using an extruder, a rubber roll machine, a Banbury mixer, or the like.

(Manufacture of boron nitride nanosheet composite)
In the method for producing a boron nitride nanosheet composite of the present invention, the method of mixing the boron nitride and the superacid is not particularly limited, but may be mixed all at once or divided and mixed. As for the order, the super acid may be added to the boron nitride, the boron nitride may be added to the super acid, or the boron nitride and the super acid may be added simultaneously. Alternatively, at least a portion may be added alternately.

  In the method for producing a boron nitride nanosheet composite according to the present invention, when the boron nitride and the superacid are mixed, another solvent, resin, filler, or additive may be added. As a solvent and a filler, what was demonstrated by the said boron nitride nanosheet composite containing dispersion liquid can be used. Mixing of such resins and additives may be performed all at once or separately. Further, the mixing order is not particularly limited.

  Further, in such a method for producing a boron nitride nanosheet composite of the present invention, the mixing ratio of the boron nitride and the superacid is not particularly limited, but the amount of the superacid added is the boron nitride 100. 0.1 parts by mass or more, preferably 0.5 parts by mass or more, more preferably 1.0 parts by mass or more, particularly preferably 2.0 parts by mass or more, and 3.0 parts by mass or more with respect to parts by mass. Is most preferred. When the added amount of the super acid is less than the lower limit, the dispersibility of the boron nitride nanosheet composite in a solvent or resin tends to be lowered. In addition, the amount of the superacid added is preferably 100000000 parts by mass or less, more preferably 10000000 parts by mass or less, and still more preferably 1000000 parts by mass or less, based on 100 parts by mass of the boron nitride, from the viewpoint of improving productivity. It is particularly preferably 500,000 parts by mass or less, and most preferably 100,000 parts by mass or less.

  Further, in such a method for producing a boron nitride nanosheet composite of the present invention, the temperature at the time of mixing the superacid with the boron nitride and / or boron nitride nanosheet is not particularly limited, However, room temperature (23 ° C.) or higher is more preferable, and 30 ° C. or higher is even more preferable.

  In the method for producing a boron nitride nanosheet composite of the present invention, the superacid is adsorbed on the boron nitride nanosheet by the mixing (mixing process), and then dropped as it is or dropped into water and / or an organic solvent. After the boron nanosheet composite-containing dispersion, filtration, centrifugal separation and / or combination of standing and filtration, reprecipitation, solvent removal (drying, etc.), and melt-kneading with the solvent included as necessary The boron nitride nanosheet composite can be sampled to obtain a boron nitride nanosheet composite. The filtration is washing filtration using water and / or an organic solvent, and removes the covalent bond (coordination bond) between the N atom on the plane of the obtained boron nitride nanosheet and the proton of superacid, and boron nitride. It is preferable from the viewpoint of reducing defects on the nanosheet plane or removing unadsorbed superacid to improve the thermal conductivity of the boron nitride nanosheet composite and the resin composition comprising the same, and cleaning with a solvent containing at least water More preferably, it is filtration. The capacity of the water is not particularly limited, but the capacity of the superacid used in the production is from the point of removing the covalent bond between the N atom on the plane of the boron nitride nanosheet and the proton of the superacid or removing the unadsorbed superacid. Is preferably 3 times or more, more preferably 5 times or more.

  In addition, when performing a mixing process in the delamination process of this invention, especially an ultrasonic process or a stirring process, it is preferable to perform centrifugation operation and / or standing after a mixing process. Centrifugation and / or standing is to remove large particles with insufficient separation and boron nitride particles that are difficult to separate due to physical entanglement in the dispersion after mixing. The supernatant after removing large particles by operation or standing is further filtered and / or dried to remove at least a part of the solvent or / and unadsorbed superacid when using the solvent to obtain a boron nitride nanosheet composite. be able to. In addition, although it does not restrict | limit especially as a rotational speed in centrifugation operation, It is preferable to exist in the range of 300-100000 rpm, and it is more preferable to exist in the range of 500-10000 rpm. When the rotation speed exceeds the upper limit, the concentration of boron nitride nanosheets in the supernatant tends to decrease. On the other hand, when the rotation speed is lower than the lower limit, the ratio of 10 or less layers of boron nitride nanosheets decreases, and the nitrogen boron nanosheets The dispersibility of the composite tends to decrease. The relative centrifugal acceleration is not particularly limited, but is preferably in the range of 10 to 1000000 G, and more preferably in the range of 100 to 100000 G. When the relative centrifugal acceleration exceeds the upper limit, the concentration of boron nitride nanosheets in the supernatant liquid tends to decrease. On the other hand, when the relative centrifugal acceleration is less than the lower limit, the ratio of boron nitride nanosheets of 10 layers or less decreases, and nitrogen boron There exists a tendency for the dispersibility of a nanosheet composite to fall. The time for the centrifugation operation is not particularly limited, but is preferably in the range of 1 minute to 24 hours, and more preferably in the range of 5 minutes to 2 hours. When the time of the centrifugation operation exceeds the upper limit, the concentration of the boron nitride nanosheets in the supernatant tends to decrease, and on the other hand, the ratio of the boron nitride nanosheets of 10 layers or less decreases below the lower limit, and The dispersibility of the nitrogen boron nanosheet composite tends to decrease. Further, when allowed to stand, the lower limit of the standing time is not particularly limited, but is preferably 5 minutes or more, more preferably 10 minutes or more, further preferably 1 hour or more, and more preferably 10 hours or more. Particularly preferred is 20 hours or longer. The upper limit of the standing time is not particularly limited, but is preferably 30 days or less, more preferably 15 days or less, and even more preferably 10 days or less. If the standing time exceeds the upper limit, the concentration of boron nitride nanosheets in the supernatant tends to decrease. On the other hand, if it is less than the lower limit, the proportion of boron nitride nanosheets of 10 layers or less decreases, and boron boron There exists a tendency for the dispersibility of a nanosheet composite to fall.

In the method for producing a boron nitride nanosheet composite of the present invention, the obtained boron nitride nanosheet composite is subjected to, for example, a heat treatment at a temperature of 150 ° C. or higher, a treatment using an alkali, a powerful washing treatment, The superacid is substantially removed by decomposing or removing at least part of the superacid adsorbed on the surface of the boron nitride nanosheet by performing a treatment such as ultrasonic treatment or electron beam irradiation for a long time. Boron nitride nanosheets removed from the surface can be produced. In addition, the boron nitride nanosheet composite and the boron nitride nanosheet composite-containing dispersion of the present invention include a heat treatment at a high temperature, a treatment using an alkali, a strong cleaning treatment, a strong and / or long-time ultrasonic treatment, an electron A small amount of NH ₂ groups or OH groups are present on the plane or end of the boron nitride nanosheet of the boron nitride nanosheet composite, in which at least part of the superacid has been changed to a superacid-derived residue by treatment such as irradiation In such a case, those containing an organic residue such as an alkyl group by an organic reaction utilizing these functional groups are also included.

  Furthermore, when the superacid is adsorbed to the boron nitride nanosheet by the production method, the superacid can be recovered and reused by filtering the dispersion after mixing, if necessary. Furthermore, a boron nitride nanosheet-containing dispersion or a boron nitride nanosheet composite can also be produced by collecting and reusing the non-peeled boron nitride particles precipitated by a centrifugal operation or the like. The boron nitride nanosheet composite can also be recovered by reprecipitation with a poor solvent for the superacid. Furthermore, by adding a boron nitride nanosheet dispersed in a superacid, preferably a boron nitride nanosheet composite adsorbed with a superacid, to the water or an organic solvent, the solvent can be converted from the superacid to water or an organic solvent. .

[Boron nitride nanosheet thin layer]
Next, the boron nitride nanosheet thin layered body of the present invention will be described. The boron nitride nanosheet thin layered body of the present invention is obtained by removing superacid adsorbed on the boron nitride nanosheet composite obtained by the method for producing a boron nitride nanosheet composite of the present invention. It is characterized by. In the present invention, the superacid adsorbed on the boron nitride nanosheet composite is removed to obtain a boron nitride nanosheet (a boron nitride nanosheet thin layered body containing no boron superoxide). ) Can be obtained. Such a thin layer of boron nitride nanosheets can maintain the small number of layers and the length of one side, which are the characteristics of the boron nitride nanosheet of the boron nitride nanosheet composite of the present invention used in the production, so that it has high thermal conductivity. Excellent. Moreover, since the superacid is removed, it is excellent in long-term heat resistance that is useful when used at a temperature of 200 ° C. or higher, for example, for 10 years or longer. In addition, in the boron nitride nanosheet thin-layer body of this invention, the boron nitride nanosheet demonstrated with the boron nitride nanosheet composite body of the said this invention, its manufacturing method, etc. can be used.

[Method for producing thin layer of boron nitride nanosheet]
Next, the manufacturing method of the boron nitride nanosheet thin layered body of the present invention will be described. The method for producing a thin layer of boron nitride nanosheet according to the present invention uses a boron nitride nanosheet composite obtained by the method for producing a boron nitride nanosheet composite according to the present invention, and is adsorbed on the boron nitride nanosheet composite. The thin film body of boron nitride nanosheets is obtained by removing the acid. In such a method for producing a thin layer of boron nitride nanosheets of the present invention, the superacid adsorbed on the boron nitride nanosheet composite is removed so that the boron nitride nanosheet does not contain a thinned superacid. It can be set as a boron nitride nanosheet (boron nitride nanosheet thin layer body). In addition, in the manufacturing method of the boron nitride nanosheet thin-layer body of this invention, the boron nitride nanosheet demonstrated with the boron nitride nanosheet composite of the said this invention, its manufacturing method, etc. can be used.

  The superacid removal method in the method for producing the boron nitride nanosheet thin layered body of the present invention is not particularly limited, but for example, heat treatment at a temperature of 150 ° C. or higher, treatment using an alkali, powerful washing treatment It is preferable that the treatment is intense and / or prolonged ultrasonic treatment, electron beam irradiation or the like. Among these superacid removal methods, the number of layers of boron nitride nanosheets of the boron nitride nanosheet composite and the size of a large side are maintained, and from the viewpoint of producing boron nitride nanosheets excellent in thermal conductivity and long-term heat resistance, 150 More preferably, it is a heat treatment at a temperature of at least 200 ° C., more preferably a heat treatment at a temperature of at least 200 ° C., particularly preferably a heat treatment at a temperature of at least 250 ° C., and at least 300 ° C. Most preferably, the heat treatment is performed at a temperature of Although it does not restrict | limit especially as heat processing time, From a viewpoint of suppressing the restacking of the boron nitride nanosheet at the time of removing a super acid, it is preferable that it is 1 minute or more, and it is more preferable that it is 10 minutes or more, 30 More preferably, it is at least minutes.

[Resin composition]
Next, the resin composition using the boron nitride nanosheet composite of the present invention will be described. The resin composition using the boron nitride nanosheet composite of the present invention contains the boron nitride nanosheet composite of the present invention and a resin.

  Since the boron nitride nanosheet composite of the present invention has a smaller number of layers than boron nitride, its specific surface area is large, and superacid adsorbed on the surface is excellent in affinity with organic solvents and resins. When used as a resin filler, the properties of the resulting resin composition can be improved even if the amount added is small.

  The content of the boron nitride nanosheet composite in such a resin composition is not particularly limited, but is preferably 0.01% by mass or more, more preferably 0.05% by mass or more with respect to 100% by mass of the resin composition. 0.1% by mass or more is more preferable, 0.2% by mass or more is particularly preferable, 90% by mass or less is preferable, 50% by mass or less is more preferable, 10% by mass or less is further preferable, and 5% by mass or less. Is particularly preferred. If the content of the boron nitride nanosheet composite is less than the lower limit, the effect of improving the thermal conductivity and mechanical strength of the resin composition of the present invention tends to be difficult to obtain. The fluidity tends to decrease.

  The resin in such a resin composition is not particularly limited, but epoxy resin, phenol resin, melamine resin, thermosetting polyimide resin, thermosetting polyamideimide, thermosetting silicone resin, urea resin, unsaturated polyester Thermosetting resins such as resin, urea resin, benzoguanamine resin, alkyd resin, and urethane resin; polystyrene, HIPS (high impact polystyrene), ABS (acrylonitrile-butadiene-styrene) resin, AS (acrylonitrile-styrene) resin, MAS Aromatic vinyl resins such as (methyl methacrylate-acrylonitrile-styrene) resin, MABS (methyl methacrylate-acrylonitrile-butadiene-styrene) resin, and SBS (styrene-butadiene-styrene) resin; Acrylic resins such as methyl oxalate, polymethyl acrylate, polymethacrylic acid, copolymers thereof, and acrylic rubber, vinyl cyanide resins such as polyacrylonitrile, acrylonitrile-methyl acrylate resin, and acrylonitrile-butadiene resin, imide Polyolefin resins such as group-containing vinyl resins, polyethylene, polypropylene, polyisoprene, polybutadiene, ethylene propylene diene monomer rubber, and ethylene propylene rubber, acid or acid anhydride modified polyolefin resins, epoxy modified polyolefin resins, acids or acid anhydrides Modified acrylic elastomer, epoxy modified acrylic elastomer, silicone rubber, fluoro rubber, natural rubber, polycarbonate, cyclic polyolefin, polyamide, polyethylene Terephthalate, polypropylene terephthalate, polybutylene terephthalate, poly 1,4-cyclohexanedimethyl terephthalate, polyarylate, liquid crystal polyester, polyphenylene ether, polyarylene sulfide, polysulfone, polyether sulfone, polyoxymethylene, polytetrafluoroethylene, fluorinated Fluorine resins such as ethylene propylene, polychlorotrifluoroethylene, polyvinylidene fluoride and polyvinyl fluoride, polylactic acid, polyvinyl chloride, thermoplastic polyimide, thermoplastic polyamideimide, polyetherimide, polyetheretherketone, poly Examples thereof include thermoplastic resins such as ether ketone ketone and polyether amide. These resins may be used alone or in combination of two or more.

  Among the resins in such a resin composition, a transparent resin (for example, polystyrene, SBS resin, polymethyl methacrylate, polymethyl acrylate, polymethacrylic acid, from the viewpoint that the whiteness of the boron nitride nanosheet can be utilized. These copolymers, acrylic resins such as acrylic rubber, polycarbonate (including special polycarbonate), cyclic polyolefin, transparent ABS resin, AS resin, MAS resin, transparent MABS resin, polyetheretherketone, polymethylpentene, fluorene series Polyester, polyethylene naphthalate, alicyclic epoxy resin, transparent polyimide, transparent polyamide, transparent fluororesin, polylactic acid, conductive polymer, and transparent elastomer) can be more preferably used. Further, from the viewpoint of thermal conductivity and mechanical strength, crystalline resins (for example, polyolefin resins such as polyethylene, polypropylene, polyisoprene, polybutadiene, polyamide, polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, poly 1,4-cyclohexanedimethyl are used. Fluorine resins such as terephthalate, liquid crystal polyester, polyarylene sulfide, polyoxymethylene, polytetrafluoroethylene, fluorinated ethylene propylene, polychlorotrifluoroethylene, polyvinylidene fluoride and polyvinyl fluoride, polylactic acid, polyether ether ketone, Polyether ketone ketone, polyether amide, etc.) can be used more preferably.

  In addition, in such a resin composition, various additives can be mix | blended as needed. Examples of such additives include, but are not limited to, flame retardants, antioxidants, ultraviolet absorbers, antistatic agents, lubricants, mold release agents, crystal nucleating agents, viscosity modifiers, colorants, and silane couplings. Surface treatment agents such as agents, clay minerals such as talc and montmorillonite, layered silicates represented by mica minerals and kaolin minerals, glass fibers, carbon fibers, fillers such as silica and heat conductive fillers, elastomers, etc. Can be mentioned.

  Such a heat conductive filler is not particularly limited, but for example, alumina, boron nitride, aluminum nitride, silicon nitride, silicon carbide, diamond, zinc oxide, graphite, carbon fiber, carbon nanofiber, carbon nanotube, carbon Examples thereof include carbon-based nanofillers such as nanoplatelets, graphene, several-layer graphene, nanographite (graphene nanoribbon, etc.), nanographene, carbon nanohorn, carbon nanocone, carbon nanocoil, and fullerene. These thermally conductive fillers may be used alone or in combination of two or more. The thermal conductivity of such a thermally conductive filler is not particularly limited, but is preferably 0.5 W / (m · K) or more, more preferably 1 W / (m · K) or more, and 5 W / (m · K). Or more), more preferably 10 W / (m · K) or more, and most preferably 20 W / (m · K) or more. Although it does not restrict | limit especially as a content rate of the heat conductive filler in such a resin composition, 0.1-95 mass% is preferable with respect to 100 mass% of resin compositions, and 0.1-90 mass% is more. Preferably, 0.1-80 mass% is further more preferable, 0.1-70 mass% is especially preferable, and 0.1-50 mass% is the most preferable. When the content of the heat conductive filler is less than the lower limit, the thermal conductivity of the resulting resin composition tends not to be sufficiently improved. On the other hand, when the content exceeds the upper limit, the fluidity of the resin composition decreases. It tends to be easy.

  The boron nitride nanosheet composite used in the preparation of such a resin composition may be subjected to a drying treatment or may contain a solvent (an organic solvent and / or water). The temperature of the drying treatment is not particularly limited, but freeze drying is preferable from the viewpoint of preventing aggregation during drying. Further, when the boron nitride nanosheet composite is agglomerated, it is rapidly dispersed in the resin even if it is used as it is, but it is preferable that the boron nitride nanosheet composite is crushed in advance by pulverization or freeze pulverization.

  A method for producing such a resin composition is not particularly limited, and examples thereof include conventionally known mixing methods that are employed when dispersing fillers in a resin. For example, the resin and the nitriding of the present invention using a method of mixing the resin, the boron nitride nanosheet composite of the present invention and various additives as necessary in a solvent, an extruder, a rubber roll machine, a Banbury mixer, or the like. Examples thereof include a method of melt-kneading the boron nanosheet composite and various additives as necessary. In the case of a method of mixing a resin, the boron nitride nanosheet composite of the present invention and various additives as required in a solvent, a conventionally known method such as a solution casting method, vacuum drying, reprecipitation, or the like after mixing. The resin composition in which the boron nitride nanosheet composite is dispersed can be obtained by removing by the above. The solvent used here is preferably one having affinity with the superacid used in the preparation of the boron nitride nanosheet, and the solvent is more preferably one that dissolves the resin used, and is appropriately selected depending on the type of resin used. can do. For example, chloroform, N, N-dimethylformamide, etc. can be mentioned as a solvent suitable when the acrylic resin preferably used from the viewpoint of transparency is selected as the resin. Moreover, when using a low-viscosity thermosetting resin as resin, it is also possible to mix by performing a compounding process using mixers, such as a self-revolving mixer. In addition, when mixing the boron nitride nanosheet composite of the present invention, a resin, and various additives as required, they may be mixed all at once or divided and mixed. Also, the order is not particularly limited, and after the specific components are premixed, the remaining components may be mixed. From the viewpoint of improving the dispersibility of the boron nitride nanosheet composite in the resin, it is preferable to pre-mix a part of the resin and / or various additives with the boron nitride nanosheet composite in advance. Examples of the premixing method include, for example, a method of mixing in a solvent, a method of mixing a molten resin and a boron nitride nanosheet composite, a method of mixing by a stirrer, a drive render or hand mixing, a boron nitride nanosheet composite, and the like. And a method of mixing at least a part of the resin and / or various additives at the time of production. Among such premixing methods, a method of mixing in a solvent is preferable, and at least a part of the resin and / or various additives are dissolved and / or dispersed (without dissolution) in the solvent, A method of adding and mixing the boron nitride nanosheet composite of the present invention, or a method of adding and mixing at least part of the resin and / or various additives to the dispersion containing the boron nitride nanosheet composite of the present invention. Is more preferable. In addition, the shape of the resin at the time of premixing is not particularly limited, and examples thereof include powder, pellets, granules, tablets, and fibers.

  Further, in such a method for producing a resin composition, a resin in which a structure similar to or similar to an anionic species constituting a superacid is introduced into a resin skeleton such as a side chain is mixed with a boron nitride nanosheet composite. By doing so, the boron nitride nanosheet composite can be highly dispersed in the resin. Moreover, it can manufacture also by mixing a boron nitride nanosheet and the said superacid in resin, and making the said superacid adsorb | suck to a boron nitride nanosheet. Preferred examples of the mixing method include a mixing method using ultrasonic treatment, vibration treatment, stirring treatment, pulverization treatment, external field application (for example, electric field application, magnetic field application, etc.), kneading and the like in a solvent.

  In addition, the method for producing a molded body from such a resin composition is not particularly limited, but the resin composition of the present invention includes injection molding, press molding, extrusion molding, blow molding, compression molding, gas assist molding, A resin composite material (molded body) can be obtained by performing a conventionally known molding process such as insert molding, two-color molding, molding using an external field (for example, magnetic field molding, molding using an electric field, etc.). Although it does not restrict | limit especially as shaping | molding temperature, Since the boron nitride nanosheet composite_body | complex of this invention is excellent in heat resistance, for example, shaping | molding at the high temperature of 290 degreeC or more, 300 degreeC or more, or 310 degreeC or more is also attained.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example. The physical properties of the boron nitride nanosheet-containing dispersion and the boron nitride nanosheet composite were measured by the following methods.

<Measurement method 1: Measurement of super acid adsorption amount of boron nitride nanosheet composite>
First, in each of the Examples, the obtained boron nitride nanosheet composite was subjected to vacuum drying at 80 ° C. to remove volatile components such as residual solvent, and then a thermogravimetric analyzer (“Thermo plus TG8120, manufactured by Rigaku Corporation). Temperature) from room temperature to 100 ° C. in a nitrogen atmosphere, held at 100 ° C. for 30 minutes, and then heated from 100 ° C. to 800 ° C. at a rate of temperature increase of 10 ° C./min to perform thermogravimetric analysis (TGA) Carried out. Here, as the super acid adsorption amount, the weight loss derived from super acid (including super acid-derived compounds) observed in the temperature range of 100 ° C. to 800 ° C. after being held at 100 ° C. for 30 minutes is the adsorption amount. It was. Boron nitride does not show a weight loss in the range of 100 ° C. to 800 ° C. In contrast, superacid, for example, chlorosulfonic acid shows a weight loss in the range of about 150 ° C. to about 220 ° C., and sulfuric acid generated by the reaction of chlorosulfonic acid and water adsorbed on the boron nitride nanosheets is about Weight loss occurs in the range of 290 ° C. to about 370 ° C., and trifluoromethanesulfonic acid exhibits weight loss in the range of about 160 ° C. to about 220 ° C. Therefore, boron nitride does not show a weight loss up to 800 ° C., and superacid decomposes up to 600 ° C., so that the mass reduction resulting from adsorption of superacid (including superacid-derived compounds) is reduced in the boron nitride nanosheet composite. Can be confirmed. From this, the thing derived from the super acid in the mass reduction of the boron nitride nanosheet composite was defined as the amount of superacid adsorbed on the boron nitride nanosheet composite and expressed in an amount (part by mass) relative to 100 parts by mass of the boron nitride nanosheet composite. . Here, as the amount of superacid adsorbed, the amount of superacid-derived product adsorbed is also regarded as the amount of superacid adsorbed, for example, sulfuric acid produced by the reaction between chlorosulfonic acid and water. Further, the adsorption amount of the superacid-derived compound (sulfuric acid in Examples 1 to 3 and 5 and no superacid-derived compound is confirmed in Example 4) is also an amount (part by mass) relative to 100 parts by mass of the boron nitride nanosheet. expressed.

<Measurement method 2: Dispersibility measurement of boron nitride nanosheet composite>
First, using the boron nitride nanosheet composites obtained in the examples and the comparative boron nitride nanosheets obtained in the comparative examples, 4.0 mg of each was added to 4 mL of isopropyl alcohol (IPA) and dissolved therein. Treatment (using a BRANSON tabletop ultrasonic cleaner “BRANSONIC B-220”, oscillation frequency 45 kHz) was applied for 10 minutes to disperse the boron nitride nanosheet composite or the comparative boron nitride nanosheet, respectively. Next, the supernatant obtained by allowing this dispersion to stand for 20 hours was collected to obtain a boron nitride nanosheet composite-containing dispersion or a comparative boron nitride nanosheet-containing dispersion.

  Next, with respect to the obtained boron nitride nanosheet composite-containing dispersion and comparative boron nitride nanosheet-containing dispersion, UV-visible light absorption spectra were measured using isopropyl alcohol (IPA) as a reference, and the dispersibility was determined by absorbance at 650 nm ( Sedimentation resistance and dispersion stability) were evaluated. In addition, since super acid and IPA do not show absorption at 650 nm, the larger the absorbance value at 650 nm, the more boron nitride nanosheet composites or boron nitride nanosheets are dispersed in the dispersion liquid after the centrifugation operation. Means excellent.

<Measurement Method 3: Boron Nitride Nanosheet Concentration Measurement in Boron Nitride Nanosheet Complex-Containing Dispersion>
Using the boron nitride nanosheet composite-containing dispersion obtained in the measurement of dispersibility of the boron nitride nanosheet composite (Measurement Method 2) (in the case of a comparative example, a comparative boron nitride nanosheet-containing dispersion) The concentration of the boron nitride nanosheet was measured.

  First, the mass of Kiriyama funnel [filter: filter made of Teflon (registered trademark), pore diameter: 0.1 μm] used for washing filtration was measured in advance. Next, the dispersion is subjected to suction filtration using a Teflon (registered trademark) filter while being washed with acetone (3 times the amount of the dispersion is used in several portions), and boron nitride nanosheet composite (In the case of a comparative example, boron nitride nanosheet) The super-acid which was not adsorbed on the surface was completely removed. Subsequently, about the filter made from Teflon (trademark) with the filter cake after washing filtration, the mass after vacuum-drying at 80 degreeC for 12 hours was measured. The mass of the Teflon (registered trademark) filter was subtracted from this mass, and the mass of the boron nitride nanosheet composite (in the case of the comparative example, boron nitride nanosheet) was calculated.

  Next, using a thermogravimetric analyzer (“Thermo plus TG8120” manufactured by Rigaku Corporation), the temperature was raised from room temperature to 100 ° C. in a nitrogen atmosphere, held at 100 ° C. for 30 minutes, and then heated at a rate of 10 ° C. The ratio of boron nitride nanosheets from which superacid adsorbed was removed from the boron nitride nanosheet composite was calculated by thermogravimetric analysis (TGA) performed by heating from 100 ° C. to 800 ° C. per minute, and nitriding boron nitride nanosheets The concentration in the boron nanosheet composite-containing dispersion (in the case of the comparative example, the concentration of the boron nitride nanosheet in the comparative boron nitride nanosheet-containing dispersion) was determined.

<Measurement method 4: Yield measurement of boron nitride nanosheet composite>
In each of the examples, the mass of the obtained boron nitride nanosheet composite is measured, and the ratio of boron nitride nanosheets excluding the amount of superacid adsorbed from the boron nitride nanosheet composite is calculated by the thermogravimetric analysis. Thus, the mass of the boron nitride nanosheet in the obtained boron nitride nanosheet composite was determined, and the yield relative to the boron nitride used as a raw material was determined to be the yield of the boron nitride nanosheet composite.
Yield (%) of boron nitride nanosheet composite: 100 × (mass of boron nitride nanosheet in the obtained boron nitride nanosheet composite) / (mass of boron nitride used as raw material)
<Measurement method 5: measurement of the number of boron nitride nanosheet layers of the boron nitride nanosheet composite>
In each of the examples and comparative examples, the obtained boron nitride nanosheet composite (in the case of the comparative example, boron nitride nanosheet) was placed in isopropyl alcohol (IPA) and subjected to ultrasonic treatment (BRANSON's tabletop ultrasonic cleaner “ BRANSONIC B-220 "(oscillation frequency 45 kHz) was applied for 3 minutes, the dispersion was dropped onto the grid, vacuum-dried at room temperature, and then accelerated at 200 kV with a high-resolution transmission electron microscope (HRTEM). Observations were made. The number of layers of the boron nitride nanosheet was measured (confirmed) by observing the edge portion of the boron nitride nanosheet. In addition, since the boron nitride nanosheet has a sheet shape, a small thickness, and flexibility, the edge portion is easily curved, so that the number of layers at the edge portion can be observed.

(Boron nitride)
In the examples and comparative examples, the following boron nitride was used. In addition, the average secondary particle diameter of boron nitride is an arbitrary 20 secondary particles (herein, each particle forms an aggregated secondary particle in an electron micrograph obtained by scanning electron microscope (SEM) observation). ) Was measured, and the average secondary particle size was obtained. In addition, the size of one side of the boron nitride primary particles (plate-like boron nitride) forming the secondary particles was measured by measuring the size of any 20 sides in the scanning electron micrograph as described above, and the average value thereof. It was. Here, the size of one side of the boron nitride primary particles indicates the length of the long side.
Boron nitride (a-1):
Hexagonal boron nitride HP-P1 manufactured by Mizushima Alloy Iron Co., Ltd., average secondary particle size: 1.4 μm, average size of one side of boron nitride primary particles: 0.5 μm, boron nitride purity: 98.3 mass%.
Boron nitride (a-2):
Showa Denko Co., Ltd. hexagonal boron nitride UHP-1K, average secondary particle size: 24 μm, average size of one side of boron nitride primary particles: 4 μm, boron nitride purity: 99.9 mass%.
Boron nitride (a-3):
Hexagonal boron nitride UHP-S1, manufactured by Showa Denko KK, average secondary particle size: 0.8 μm, average size of one side of boron nitride primary particles: 0.4 μm, boron nitride purity: 99.8 mass%.

(Super acid)
In the examples and comparative examples, the super acids shown below were used.
Superacid (b-1):
Chlorosulfonic acid (Hammett acidity function (H ₀ ): −13.8 (25 ° C.)).
Superacid (b-2):
Trifluoromethanesulfonic acid _{(H 0: -14.1 (25 ℃} )).

(Acids other than super acids)
In the comparative examples, the following acids were used as acids other than superacids.
Acids other than super acids (c-1):
98% concentrated sulfuric acid (H ₀ : 10.43 (25 ° C.)).
Acids other than super acids (c-2):
Methanesulfonic acid (H ₀ : -1 (25 ° C.)).

(Example 1)
Preparation of boron nitride nanosheet-containing dispersion and boron nitride nanosheet composite-containing dispersion :
First, 100 mg of hexagonal boron nitride (a-1) was added to a 100 mL two-necked flask and subjected to flame drying at 500 ° C. for 1 hour under vacuum to remove moisture from the boron nitride and the flask. Next, the flask was filled with nitrogen, and 20 mL of superacid (b-1) was added dropwise under a nitrogen atmosphere. This was then subjected to ultrasonic treatment (using a BRANSON tabletop ultrasonic cleaner “BRANSONIC B-220”, oscillation frequency 45 kHz) for 8 hours under a nitrogen atmosphere, so that the boron nitride nanosheets became superacid (b-1). A dispersion containing boron nitride nanosheets dispersed therein was obtained. The resulting dispersion was colored light brown.

  Next, the obtained boron nitride nanosheet-containing dispersion liquid is dropped dropwise into a beaker containing 100 times the volume of pure water and a stirrer while slowly stirring, and transferred to pure water. A white dispersion was obtained. Next, the obtained dispersion was allowed to stand for 24 hours to precipitate coarse particles and undispersed particles, and then the supernatant was recovered, and the boron nitride nanosheet composite was superacid (b-1) (derived from superacid). A boron nitride nanosheet composite-containing dispersion liquid dispersed in a mixed solvent of a compound containing a compound and pure water was obtained.

Preparation of boron nitride nanosheet composite :
Next, the boron nitride nanosheet composite-containing dispersion obtained above is filtered using a Kiriyama funnel [filter: Teflon (registered trademark) filter, pore size: 0.1 μm], and a plurality of 100 mL of pure water is further added. The filter cake was washed and filtered in several batches, and unadsorbed superacid was completely removed from the boron nitride nanosheet surface. Thereafter, the filter cake is vacuum-dried at 80 ° C. for 12 hours to completely distill off the solvent, and the boron nitride nanosheet composite in which the superacid and the superacid-derived compound (sulfuric acid) are adsorbed on the boron nitride nanosheet and colored in a light brown color. Got the body.

  Measurement of the super acid adsorption amount, dispersibility measurement, and yield measurement of the obtained boron nitride nanosheet composite were performed by the measurement method 1, the measurement method 2, and the measurement method 4, respectively. The obtained results are shown in Table 1.

  Further, for the obtained boron nitride nanosheet composite, using the boron nitride nanosheet composite-containing dispersion obtained in the dispersibility measurement (measurement method 2), measurement of the concentration of the boron nitride nanosheet in the dispersion, The measurement was performed by the measurement method 3. The obtained results are shown in Table 1. Further, the obtained boron nitride nanosheet composite was subjected to X-ray photoelectron spectroscopy analysis (manufactured by ULVAC-PHI Co., Ltd., “Quantera SXM”, X-ray source: monochromatic AlKα ray (1486.6 eV), photoelectron extraction angle ： 45 °, analysis region: 200 μmφ) As a result of measuring the spectrum of N1s, a peak of about 398 eV corresponding to the N atom of boron nitride was observed. The peak of the N atom to which the proton generated by the coordination bond is bonded (observed in the range of about 400 eV to 402 eV) was not confirmed. From this result, it was confirmed that the boron nitride nanosheet composite of Example 1 obtained by washing with a large amount of water was a superacid (b-1) adsorbed to the boron nitride nanosheet by noncovalent bonding. .

(Example 2)
A boron nitride nanosheet-containing dispersion and a boron nitride nanosheet composite were prepared in the same manner as in Example 1 except that boron nitride (a-2) was used instead of boron nitride (a-1). In addition, the boron nitride nanosheet-containing dispersion before transferring to the pure water obtained in the preparation of the boron nitride nanosheet-containing dispersion and the boron nitride nanosheet composite-containing dispersion is colored in an extremely thin light yellow color. The boron nitride nanosheet composite-containing dispersion after the transfer was white. Further, the obtained boron nitride nanosheet composite was very lightly brown.

  About the obtained boron nitride nanosheet composite, super acid adsorption amount measurement, dispersibility measurement, boron nitride nanosheet concentration measurement in the boron nitride nanosheet composite-containing dispersion, and yield measurement of boron nitride nanosheet composite 1 was performed. The results are shown in Table 1.

  Moreover, about the obtained boron nitride nanosheet composite_body | complex, the number of layers of the boron nitride nanosheet was confirmed according to the said method (measurement method 5). For each sample, the number of layers was confirmed by observing the edges of 25 arbitrary boron nitride nanosheets, and the ratio of nanosheets having a structure of 10 layers or less, 6 layers or less, 3 layers or less, 2 layers or less, and a single layer structure Asked. Moreover, about the boron nitride nanosheet composite, the length of one side of the boron nitride nanosheet was confirmed by scanning electron microscope observation. About the electron micrograph obtained by scanning electron microscope observation, the length of one side of 20 arbitrary boron nitride nanosheet composites was measured, and the average value was obtained. Here, the length of one side of the boron nitride nanosheet refers to the length of the long side. The obtained results are shown in Table 2.

  Further, the boron nitride nanosheet composite obtained in Example 2 was subjected to X-ray photoelectron spectroscopic analysis in the same manner as in Example 1. As a result, a peak of about 398 eV corresponding to the N atom of boron nitride was observed. The N1s spectrum (observed in the range of about 400 eV to 402 eV) corresponding to the coordination bond to the N atom of the boron nitride nanosheet plane of the proton of superacid was not confirmed, and was obtained by washing with a large amount of water. It was confirmed that the boron nitride nanosheet composite of Example 2 was a super acid (b-1) adsorbed on the boron nitride nanosheet by a noncovalent bond.

(Example 3)
A boron nitride nanosheet-containing dispersion and a boron nitride nanosheet composite were prepared in the same manner as in Example 1 except that boron nitride (a-3) was used instead of boron nitride (a-1). In addition, the boron nitride nanosheet-containing dispersion before transferring to the pure water obtained in the preparation of the boron nitride nanosheet-containing dispersion and the boron nitride nanosheet composite-containing dispersion is colored in an extremely thin light yellow color. The boron nitride nanosheet composite-containing dispersion after the transfer was white. Further, the obtained boron nitride nanosheet composite was very lightly brown.

  About the obtained boron nitride nanosheet composite, super acid adsorption amount measurement, dispersibility measurement, boron nitride nanosheet concentration measurement in the boron nitride nanosheet composite-containing dispersion, and yield measurement of boron nitride nanosheet composite 1 was performed. The results are shown in Table 1.

  Further, as a result of measuring the spectrum of N1s by X-ray photoelectron spectroscopic analysis in the same manner as in Example 1 for the boron nitride nanosheet composite obtained in Example 3, it was found that the superacid proton to the N atom in the plane of the boron nitride nanosheet The N1s spectrum corresponding to the coordination bond was not confirmed, and it was confirmed that the adsorption was due to a non-covalent bond.

Example 4
A boron nitride nanosheet-containing dispersion and a boron nitride nanosheet composite were prepared in the same manner as in Example 1 except that the superacid (b-2) was used instead of the superacid (b-1). The boron nitride nanosheet-containing dispersion before transferring to pure water obtained in the preparation of the boron nitride nanosheet-containing dispersion and the boron nitride nanosheet composite-containing dispersion was colored pale orange and transferred to pure water. The subsequent boron nitride nanosheet composite-containing dispersion was white. Further, the obtained boron nitride nanosheet composite was colored white.

  About the obtained boron nitride nanosheet composite, super acid adsorption amount measurement, dispersibility measurement, boron nitride nanosheet concentration measurement in the boron nitride nanosheet composite-containing dispersion, and yield measurement of boron nitride nanosheet composite 1 was performed. The results are shown in Table 1.

(Example 5)
First, 100 mg of hexagonal boron nitride (a-1) was added to a 100 mL two-necked flask and subjected to flame drying at 500 ° C. for 1 hour under vacuum to remove moisture from the boron nitride and the flask. Next, the flask was filled with nitrogen, and 20 mL of superacid (b-1) was added dropwise under a nitrogen atmosphere. Next, a stirring process was performed for 5 days at a rotational speed of 500 rpm using a stirrer to obtain a boron nitride nanosheet-containing dispersion. The resulting dispersion was very light and brown.

  Next, the obtained boron nitride nanosheet-containing dispersion containing pure water and a stirrer in a volume 100 times that of the dispersion was dropped into a beaker cooled in an ice bath while slowly stirring, drop by drop, It moved to the pure water and the white dispersion liquid was obtained. Next, the obtained dispersion was allowed to stand for 24 hours to precipitate coarse particles and undispersed particles, and then the supernatant was recovered, and the boron nitride nanosheet composite was superacid (b-1) (derived from superacid). A boron nitride nanosheet composite-containing dispersion dispersed in a mixed solvent of a compound (including a compound) and pure water was obtained.

  Next, in the same manner as in Example 1, the boron nitride nanosheet composite-containing dispersion obtained above was filtered using a Teflon (registered trademark) filter, and 100 mL of pure water was further divided into a plurality of times. The filter cake was washed and filtered, and unadsorbed superacid was completely removed from the surface of the boron nitride nanosheet. Thereafter, the filter cake was vacuum-dried at 80 ° C. for 12 hours to completely distill off the solvent, thereby obtaining a white boron nitride nanosheet composite.

  About the obtained boron nitride nanosheet composite, super acid adsorption amount measurement, dispersibility measurement, boron nitride nanosheet concentration measurement in the boron nitride nanosheet composite-containing dispersion, and yield measurement of boron nitride nanosheet composite 1 was performed. The results are shown in Table 1.

(Comparative Example 1)
First, 100 mg of hexagonal boron nitride (a-1) after vacuum drying at 80 ° C. for 12 hours in a screw tube bottle and 20 mL of dimethylformamide (DMF, manufactured by Kanto Chemical Co., Ltd.) as a solvent instead of superacid Then, this was subjected to ultrasonic treatment (using a BRANSON desktop ultrasonic cleaner “BRANSONIC B-220”, oscillation frequency 45 kHz) for 8 hours to obtain a dispersion. Next, this dispersion was allowed to stand for 24 hours to precipitate coarse particles and undispersed particles, and the resulting supernatant was recovered to obtain a boron nitride nanosheet-containing dispersion for comparison.

  Next, the boron nitride nanosheet-containing dispersion obtained above was filtered using a Kiriyama funnel [filter: filter made of Teflon (registered trademark), pore size: 0.1 μm], and further 100 mL of isopropyl alcohol (IPA, sum). The filter cake was washed and filtered by using multiple times (manufactured by Kojun Pharmaceutical Co., Ltd.). Thereafter, the filter cake was vacuum-dried at 80 ° C. for 12 hours to completely distill off the solvent, thereby obtaining a boron nitride nanosheet for comparison.

  About the obtained boron nitride nanosheet for comparison, as a result of thermogravimetric analysis according to the measurement method 1 as an adsorption amount measurement of a solvent such as DMF or IPA, a weight reduction derived from a solvent such as DMF or IPA was confirmed. No adsorption of the solvent used was observed.

  Moreover, the dispersibility measurement of the obtained boron nitride nanosheet for comparison and the boron nitride nanosheet density | concentration measurement in the boron nitride nanosheet composite containing dispersion liquid were performed by the said measuring method 2 and 3 similarly to Example 1. FIG. The results are shown in Table 1.

  Furthermore, the yield of the obtained boron nitride nanosheet for comparison is measured according to the measurement method 4, the mass of the boron nitride nanosheet for comparison is measured, the yield with respect to boron nitride used as a raw material is obtained, and the nitridation for comparison is performed. The yield of boron nanosheets was used. The results are shown in Table 1.

(Comparative Example 2)
A comparative boron nitride nanosheet-containing dispersion and a comparative boron nitride nanosheet were prepared in the same manner as in Comparative Example 1 except that boron nitride (a-2) was used instead of boron nitride (a-1).

  About the obtained boron nitride nanosheet for comparison, the amount of adsorption of the solvent was measured in the same manner as in Comparative Example 1. As a result, no weight reduction derived from the solvent was confirmed, and no adsorption of the solvent used was observed.

  Moreover, the dispersibility measurement of the obtained comparative boron nitride nanosheet and the boron nitride nanosheet concentration measurement in the boron nitride nanosheet composite-containing dispersion were performed in the same manner as in Example 1. The results are shown in Table 1.

  Furthermore, the yield of the obtained comparative boron nitride nanosheet was measured in the same manner as in Comparative Example 1. The results are shown in Table 1.

  Further, the number of layers of the obtained comparative boron nitride nanosheet and the length of one side of the boron nitride nanosheet were measured in the same manner as in Example 2. The results are shown in Table 2.

(Comparative Example 3)
A comparative boron nitride nanosheet-containing dispersion and comparative nitridation in the same manner as in Comparative Example 2, except that isopropyl alcohol (IPA, manufactured by Wako Pure Chemical Industries, Ltd.) was used instead of DMF as a solvent instead of superacid. Boron nanosheets were prepared.

  About the obtained boron nitride nanosheet for comparison, the amount of adsorption of the solvent was measured in the same manner as in Comparative Example 1. As a result, no weight reduction derived from the solvent was confirmed, and no adsorption of the solvent used was observed.

  Moreover, the dispersibility measurement of the obtained comparative boron nitride nanosheet and the boron nitride nanosheet concentration measurement in the boron nitride nanosheet composite-containing dispersion were performed in the same manner as in Example 1. The results are shown in Table 1.

  Furthermore, the yield of the obtained comparative boron nitride nanosheet was measured in the same manner as in Comparative Example 1. The results are shown in Table 1.

(Comparative Example 4)
100 mg of hexagonal boron nitride (a-2) and 20 mL of acid (c-1) after vacuum drying at 80 ° C. for 12 hours are put into a 100 mL two-necked flask, and this is subjected to ultrasonic treatment (table type manufactured by BRANSON) Using an ultrasonic cleaner “BRANSONIC B-220” (oscillation frequency 45 kHz) for 8 hours, a boron nitride nanosheet-containing dispersion for comparison was obtained. The resulting dispersion was white. Next, a comparative boron nitride nanosheet was prepared from the dispersion by the same method as in Example 1.

  About the obtained boron nitride nanosheet for comparison, the amount of adsorption of the solvent was measured in the same manner as in Comparative Example 1. As a result, no weight reduction corresponding to the acid (c-1) was confirmed, and the adsorption of the acid (c-1) was confirmed. Was not allowed. From this result, 98% concentrated sulfuric acid was not adsorbed on the boron nitride nanosheet, and the superacid-derived compound was produced in the boron nitride nanosheet composite produced using superacid (b-1) in Examples 1 to 3 and 5. The reason why the adsorption of sulfuric acid was confirmed is considered to be that after superacid was once adsorbed on the surface of the boron nitride nanosheet, at least a part of it produced sulfuric acid by reaction with water.

  Moreover, the dispersibility measurement of the obtained comparative boron nitride nanosheet and the boron nitride nanosheet concentration measurement in the boron nitride nanosheet composite-containing dispersion were performed in the same manner as in Example 1. The results are shown in Table 1.

  Furthermore, the yield of the obtained comparative boron nitride nanosheet was measured in the same manner as in Comparative Example 1. The results are shown in Table 1.

(Comparative Example 5)
Except for using boron nitride (a-2) instead of boron nitride (a-1) and using acid (c-2) other than superacid as a solvent instead of superacid, the same procedure as in Example 1 was performed. A comparative boron nitride nanosheet dispersion and a comparative boron nitride nanosheet were prepared.

  About the obtained boron nitride nanosheet for comparison, the amount of adsorption of the solvent was measured in the same manner as in Comparative Example 1. As a result, the amount of adsorption of the acid (c-2) was 0.3 part by mass.

  Moreover, the dispersibility measurement of the obtained comparative boron nitride nanosheet and the boron nitride nanosheet concentration measurement in the boron nitride nanosheet composite-containing dispersion were performed in the same manner as in Example 1. The results are shown in Table 1.

  Furthermore, the yield of the obtained comparative boron nitride nanosheet was measured in the same manner as in Comparative Example 1. The results are shown in Table 1.

<Evaluation results>
As is clear from the comparison between the results of Examples 1 to 5 and the results of Comparative Examples 1 to 5 shown in Table 1, the boron nitride nanosheet-containing dispersion and the boron nitride nanosheet composite of Examples 1 to 5 were dispersed. It was confirmed that the property (dispersion stability) was excellent.

  In addition, from the comparison with Examples 1-5 and Comparative Examples 1-5, in Examples 1-5, it was confirmed that the yield of boron nitride nanosheets was increased by using superacid, and the peelability was improved. It was. Further, the boron nitride nanosheet composites obtained in Examples 1 to 5 are superior in dispersibility in IPA compared to the comparative boron nitride nanosheets of Comparative Examples 1 to 5, and the boron nitride nanosheet is a superacid. It was confirmed that a highly concentrated dispersion liquid highly dispersed therein could be produced. Further, from the comparison between Example 1 and Example 4, the use of chlorosulfonic acid in which a halogen is directly bonded to an S atom as a superacid, compared with the case of using trifluoromethanesulfonic acid, the adsorptivity and the yield. It was confirmed that the ratio and the dispersibility in IPA of the obtained boron nitride nanosheet composite were excellent. Further, from the comparison between Example 1 and Example 5, in the boron nitride nanosheet-containing dispersion liquid, it is a mixing process in which a relatively weak ultrasonic treatment is performed for a relatively short time rather than stirring at a high rotation speed for a long time. It was confirmed that the adsorptivity, yield, and dispersibility of the obtained boron nitride nanosheet composite in IPA were greatly improved.

  Further, from Table 2, it was confirmed that the boron nitride nanosheet composite of Example 2 had a smaller number of layers than that of Comparative Example 2, and boron nitride nanosheets having 3 layers or less were also obtained. Furthermore, it was confirmed that the boron nitride nanosheet composite of Example 2 had a longer side length than that of Comparative Example 2.

  As described above, according to the present invention, a boron nitride nanosheet-containing dispersion in which boron nitride nanosheets are highly dispersed in a superacid, and a boron nitride nanosheet composite excellent in dispersibility in a solvent or resin are obtained. It becomes possible. Moreover, since the boron nitride nanosheet composite of the present invention is excellent in heat resistance and oxidation resistance, it can be used at a high temperature such as being added to a high heat resistant resin or the like that requires a high temperature during production, and can be uniformly dispersed.

Accordingly, the boron nitride nanosheet-containing dispersion of the present invention, the boron nitride nanosheet composite, and the resin composition using the boron nitride nanosheet composite of the present invention can be used for applications that can make use of the inherent properties of the boron nitride nanosheet, for example, Applications that require mechanical properties, applications that require electromagnetic shielding, applications that require heat resistance, applications that require dimensionality (decrease in thermal expansion coefficient), applications that require high insulation and thermal conductivity, and electrical conductivity Can be used in a wide range of applications, such as applications that require deep ultraviolet light emission characteristics, applications that require high-temperature oxidation resistance and chemical reactivity, such as various types of mobile media such as automobiles and aircraft Parts, parts for electrical and electronic equipment, high thermal conductivity sheets, heat sinks, electromagnetic wave absorbers, insulation coatings, coatings, graphene and carbon nano Substrates for functional materials such as tubes, electrolytes for secondary batteries such as lithium secondary batteries, electric double layer capacitors (capacitors), electrolytes for fuel cells, various thermal fluids, optical device materials, microelectronic components (semiconductors) It can be suitably used for various related parts.
Further, in the production of the boron nitride nanosheet-containing dispersion and boron nitride nanosheet composite of the present invention, an expensive or complicated manufacturing process can be eliminated, and the boron nitride nanosheet-containing dispersion, boron nitride nanosheet composite, and boron nitride can be eliminated. It also becomes possible to reduce the production cost of a resin composition or the like obtained using the nanosheet composite.

Claims (12)

  A boron nitride nanosheet-containing dispersion comprising a superacid and a boron nitride nanosheet dispersed in the superacid.   The boron nitride nanosheet-containing dispersion according to claim 1, wherein at least a part of the superacid is adsorbed on the boron nitride nanosheet.   The boron nitride nanosheet-containing dispersion according to claim 1 or 2, wherein the boron nitride nanosheet includes a boron nitride nanosheet having 10 or less layers.   Boron nitride nanosheet-containing dispersion comprising mixing boron nitride and superacid to exfoliate the layers of boron nitride to obtain boron nitride nanosheets, and comprising the superacid and boron nitride nanosheets dispersed in the superacid A process for producing a dispersion containing boron nitride nanosheets.   5. The mixing includes a step of subjecting the boron nitride to at least one delamination treatment selected from the group consisting of ultrasonic treatment, stirring treatment, and pulverization treatment in the presence of the superacid. The manufacturing method of the boron nitride nanosheet containing dispersion liquid of description.   A boron nitride nanosheet composite comprising a boron nitride nanosheet and a superacid adsorbed on the boron nitride nanosheet.   The boron nitride nanosheet composite according to claim 6, wherein the boron nitride nanosheet includes a boron nitride nanosheet having 10 or less layers.   A boron nitride nanosheet composite-containing dispersion comprising the boron nitride nanosheet composite according to claim 6 or 7 and a solvent other than superacid.   A method for producing a boron nitride nanosheet composite comprising mixing boron nitride and superacid, separating the layers of boron nitride to obtain a boron nitride nanosheet, and adsorbing the superacid to the boron nitride nanosheet.   The mixing process includes a step of subjecting the boron nitride to at least one delamination treatment selected from the group consisting of ultrasonic treatment, stirring treatment, and pulverization treatment in the presence of the superacid. The manufacturing method of the boron nitride nanosheet composite_body | complex described in 2.   A boron nitride nanosheet obtained by removing superacid adsorbed on the boron nitride nanosheet composite obtained by the method for producing a boron nitride nanosheet composite according to claim 9 or 10. Thin layer body.   A boron nitride nanosheet composite obtained by the method for producing a boron nitride nanosheet composite according to claim 9 or 10, and the superacid adsorbed on the boron nitride nanosheet composite is removed to form a boron nitride nanosheet thin layer A method for producing a thin layer of boron nitride nanosheets characterized in that a body is obtained.