JP5565694B2 - Boron nitride nanotube derivative, dispersion thereof, and method for producing boron nitride nanotube derivative - Google Patents

Description

  The present invention relates to a boron nitride nanotube derivative having good dispersibility in various solvents and suitable for use in a resin composition, a dispersion thereof, and a method for producing the boron nitride nanotube derivative.

  Many nanotube materials, including carbon nanotubes, are insoluble in common solvents, and their molding and processing methods are significantly limited. If this problem is solved, it is very useful in practice, and various methods for uniformly dispersing the nanotube material in the solvent have been studied.

  For example, Non-Patent Document 1 reports that the surface of a carbon nanotube is oxidized with a mineral acid and a hydroxyl group or a carboxyl group is introduced to increase the affinity for a solvent and improve dispersibility. In addition, after converting the carboxyl group present on the surface of the carbon nanotube to acid chloride with thionyl chloride, it is reacted with an alcohol or amine having a long chain alkyl group to produce a carbon nanotube in which the long chain alkyl group is chemically bonded. It has been reported that dispersibility is improved by doing so.

  By the way, when the diameter and chirality of carbon nanotubes change, the characteristics change accordingly.On the other hand, the characteristics of boron nitride nanotubes do not change even if the diameter and chirality change. There is an advantage that there is little. Furthermore, boron nitride nanotubes have excellent mechanical properties, high thermal conductivity, excellent oxidation resistance, and wide band gap energy, so that these characteristics are required, for example, semiconductor materials, It is considered to be useful for emitter materials, heat-resistant filling materials, high-strength materials, catalysts, etc., particularly in nanometer (nm) size semiconductors that operate in oxidizing or high-temperature atmospheres. Further, by using boron nitride nanotubes as a reinforcing material for a composite material, it can be useful for improving mechanical properties and thermal conductivity of a matrix phase (also called a continuous phase) of the material. Therefore, if the dispersibility of the boron nitride nanotubes in the solvent can be improved, various molding / processing methods can be applied, and a semiconductor material having an excellent function can be obtained.

  Regarding the technology for improving the dispersibility of boron nitride nanotubes, for example, in Non-Patent Document 4, a boron nitride nanotube and an amine-terminated polyethylene glycol oligomer are heated at 100 ° C. for 3 days to thereby form a non-covalent bond therebetween. It is reported that the adduct formed by the above method is formed to improve the solubility (dispersibility) in a solvent. However, in this method, an adduct formed by non-covalent bonding is formed between the boron nitride nanotube and the amine-terminated polyethylene glycol oligomer, so that the dispersibility in a solvent, particularly an organic solvent, is low, and the time required for production is low. However, there is a problem that the yield is low.

  Patent Document 1 discloses a boron nitride nanotube comprising a boron nitride nanotube, poly [m-phenylene vinylene-co- (2,5-dioctoxy-p-phenylene vinylene)] (hereinafter referred to as a wrapping polymer), and an organic solvent. The dispersion is shown to be uniform and transparent. However, this technique requires the presence of the wrapping polymer in the liquid, and in order to remove the wrapping polymer, it is necessary to thermally decompose the wrapping polymer at a temperature of several hundred degrees Celsius after removing the organic solvent. For this reason, for example, when it is desired to obtain a cast film of a composition of a different type of polymer from the wrapping polymer and boron nitride nanotubes, the dispersion of the technology can be used because the remaining wrapping polymer is allowed. Limited to Thus, even if it is going to utilize the dispersion liquid of patent document 1 in various fields, there exists a problem that the case where it can apply is very limited.

JP 2007-230830 A

Jie Liu et al, Science, 1998, 280, p.1253 Jian Chen et al, Science, 1998, 282, p.95 Kefu Fu et al, Nano Letters, 2001, 1, p.439 Su-Yuan Xie et al, Chem. Commun., 2005, p.3670

  An object of the present invention is to provide a boron nitride nanotube derivative having good dispersibility in a solvent, a dispersion thereof, and a simple production method thereof.

  In view of the above problems, the inventors of the present invention have made extensive studies on improving the dispersibility of boron nitride nanotubes. As a result, the boron nitride nanotubes were treated with a hydrogen peroxide solution and then treated with a silylating agent. Boron nitride nanotube derivatives in which 2 atomic% or more of silicon is obtained were obtained, and it was found that the derivatives showed outstanding dispersibility in an organic medium, and the present invention was completed. The gist of the present invention is shown below.

1. A boron nitride nanotube derivative characterized in that 2 atomic% or more of the surface elemental composition is silicon.
2. The average diameter is 0.4 nm to 1 μm and the average length is 1 to 10 μm. The boron nitride nanotube derivative according to item.
3. Above 1. Term or 2. A boron nitride nanotube derivative dispersion liquid in which the boron nitride nanotube derivative described in the item is dispersed in a solvent.
4). The solvent is selected from the group consisting of alcohols, amide solvents, halogenated hydrocarbons, esters, ketones, ethers, silicon compound solvents, aromatic hydrocarbons, and aliphatic hydrocarbons containing a chain and / or cyclic structure. 2. at least one kind described above, The boron nitride nanotube derivative dispersion liquid according to item.
5. The boron nitride nanotubes were treated with a 3-70 mass% hydrogen peroxide solution or a mixed composition solution containing 3-70 mass% hydrogen peroxide and 10-1000 mass ppm of iron (II) ions, and further silylated Item 1 above, characterized by being treated with an agent. Term or 2. A method for producing the boron nitride nanotube derivative according to Item.
6). 4. The treatment with a silylating agent uses a chlorosilane compound in the presence of a base. The production method according to item.

  ADVANTAGE OF THE INVENTION According to this invention, the boron nitride nanotube derivative excellent in the dispersibility to a solvent can be provided. Moreover, according to the production method of the present invention, a boron nitride nanotube derivative can be obtained in high yield. Various molding processes can be performed using the dispersion liquid of the boron nitride nanotube derivative of the present invention.

2 is a transmission electron micrograph of a boron nitride nanotube derivative sample obtained in Example 1. FIG.

  The boron nitride nanotube derivative of the present invention is a boron nitride nanotube derivative characterized in that 2 atomic% or more of the surface element composition is silicon. The surface elemental composition of the boron nitride nanotube derivative can be determined by X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES) or the like of the boron nitride nanotube derivative. Further, the upper limit of the ratio of silicon in the surface element composition of the boron nitride nanotube derivative of the present invention is preferably 50 atomic% or less, more preferably 30 atomic% or less, and even more preferably 10 atomic% or less.

  The boron nitride nanotube derivative of the present invention preferably has an average diameter of 0.4 nm to 1 μm (1000 nm), more preferably 0.6 to 500 nm, and still more preferably 0.8 to 200 nm.

  The boron nitride nanotube derivative of the present invention has an average length of preferably 10 μm or less, more preferably 5 μm or less, an aspect ratio of 5 or more, and even more preferably 10 or more. The lower limit of the average length of the boron nitride nanotube derivative of the present invention is preferably 2 nm or more, more preferably 4 nm or more, more preferably 100 nm or more, and extremely preferably 1000 nm (1 μm) or more. The dimensions of the boron nitride nanotube derivative, such as the average diameter and the average length, are the same as those of the boron nitride nanotube as a raw material.

  The boron nitride nanotube, which is a raw material of the boron nitride nanotube derivative of the present invention, is a tube-shaped material made of boron nitride. As an ideal structure, a hexagonal mesh surface forms a tube parallel to the tube axis, It is a tube or multiple tubes.

  The boron nitride nanotubes can be synthesized generally using an arc discharge method, a laser heating method, or a chemical vapor deposition method. A method of synthesizing borazine as a raw material using nickel boride as a catalyst is also known. A method of synthesizing boron oxide and nitrogen by using carbon nanotubes as a template has also been proposed. The boron nitride nanotubes used in the present invention are not limited to those produced by a specific method, and those produced by various production methods can be used. In particular, a mixture of boron, iron (II) oxide (FeO) and magnesium oxide (MgO) was heated to 1100 to 1700 ° C. to generate boron oxide vapor, which was synthesized by causing ammonia gas to act on the generated vapor. It is preferable to use one from the viewpoint of yield and high purity. In these methods, about 0 to 1% of the surface composition of the nanotubes may be oxidized or hydroxylated depending on conditions, but due to the characteristics of the reaction, most of them are formed by boron nitride bonds preferentially. No further introduction of hydroxyl groups occurs.

  As described above, the boron nitride nanotube has the same size as the boron nitride nanotube derivative, and the average diameter of the boron nitride nanotube is preferably 0.4 nm to 1 μm (1000 nm), more preferably 0.6 to 500 nm, Even more preferably, it is 0.8 to 200 nm. The average diameter here means the average outer diameter in the case of a single pipe, and the average outer diameter of the outermost pipe in the case of a multiple pipe. The average length of the boron nitride nanotubes is preferably 10 μm or less, more preferably 5 μm or less. The aspect ratio is preferably 5 or more, more preferably 10 or more. The upper limit of the aspect ratio is not limited as long as the average length is 10 μm or less, but the upper limit is substantially 25000. Therefore, the boron nitride nanotubes preferably have an average diameter of 0.4 nm to 1 μm and an aspect ratio of 5 or more.

  The average diameter, average length, and aspect ratio of the boron nitride nanotube derivative of the present invention and the boron nitride nanotube that is a raw material thereof can be determined from observation with an electron microscope. For example, a TEM (transmission electron microscope) measurement is performed, and the diameter and the length in the longitudinal direction of the boron nitride nanotube can be directly measured from the image. The form of the boron nitride nanotubes in the composition can be grasped by, for example, TEM (transmission electron microscope) measurement of a fiber cross section cut parallel to the fiber axis.

  The boron nitride nanotube derivative of the present invention has good dispersibility in various solvents. The boron nitride nanotube derivative dispersion of the present invention, which is obtained by dispersing the boron nitride nanotube derivative in a solvent, is extremely stable and causes precipitation of the boron nitride nanotube derivative or phase separation even when stored for a long period of time, for example, one week. Absent. In addition, the boron nitride nanotube derivative of the present invention has good dispersibility in a fluorine-based solvent in which conventional boron nitride nanotubes are difficult to disperse. For example, a composite dispersion of the boron nitride nanotube derivative of the present invention and a fluorocarbon compound Therefore, it is advantageous in that an efficient molding process can be performed without causing inhomogeneity and phase separation when adjusting the composite. Considering such extremely good dispersibility and the stability of the dispersion, the boron nitride nanotubes are treated with a hydrogen peroxide solution and then further treated with a silylating agent to obtain the boron nitride nanotube derivatives of the present invention. The increment of silicon atoms in the surface elemental composition of is considered to be due to the introduction of silyl ether groups on the surface of the derivative during the treatment.

Next, the boron nitride nanotube derivative dispersion of the present invention will be described.
The boron nitride nanotube derivative dispersion of the present invention is obtained by dispersing the boron nitride nanotube derivative of the present invention in a solvent. The dispersion concentration is 0.1% of boron nitride nanotube derivative with respect to 100 parts by mass of the solvent. It is preferably -40 parts by mass, more preferably 0.3-20 parts by mass, further preferably 0.5-10 parts by mass, and extremely preferably 0.8-5 parts by mass.

  Examples of the solvent of the boron nitride nanotube derivative dispersion of the present invention include alcohols, amide solvents, halogenated hydrocarbons, esters, ketones, ethers, silicon compound solvents, aromatic hydrocarbons, which contain a chain and / or cyclic structure. And at least one kind of commonly used solvent selected from the group consisting of aliphatic hydrocarbons and the like. Specific examples of the solvent include methanol, ethanol, propanol and butanol, N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, dimethyl sulfoxide, methylene chloride, chloroform, carbon tetrachloride, Selected from the group consisting of methyl acetate, ethyl acetate, propyl acetate, butyl acetate, γ-butyrolactone, acetone, 2-butanone, tetrahydrofuran, dioxolane, dioxane, anisole, benzene, toluene, xylene, and alkoxysilane (eg, tetraethoxysilane) One or more types are preferred. Among the above solvents, in particular, one or more selected from the group consisting of chloroform, N, N-dimethylacetamide, tetrahydrofuran, γ-butyrolactone, N, N-dimethylformamide, dimethyl sulfoxide, acetone, benzene, toluene and alkoxysilane Is preferred.

  Further, as the halogenated hydrocarbon which is a solvent of the boron nitride nanotube derivative dispersion liquid of the present invention, a fluorine-based solvent is particularly preferable, and in particular, perfluorotrialkylamine, perfluorocyclic ether, perfluoro (poly) ether, ( One or more selected from the group consisting of poly) fluoro (poly) chloroalkanes, perfluoroalkanes, alicyclic fluorinated hydrocarbons and aromatic fluorinated hydrocarbons are preferred.

  Examples of the silicon compound solvent that is the solvent of the boron nitride nanotube derivative dispersion of the present invention include tetramethylsilane, hexamethyldisiloxane, decamethyltetrasiloxane, hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane. , One or more selected from the group consisting of dodecamethylcyclohexasiloxane, tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, and tetrabutoxysilane are preferable.

  In preparing the boron nitride nanotube derivative dispersion of the present invention, a method of mechanically stirring and dispersing the mixture of the boron nitride nanotube derivative and the solvent, a method of dispersing the mixture by ultrasonic treatment, Examples thereof include a method of dispersing the mixed solution by a pulverizer such as a wet jet mill or a bead mill. Among them, the method of dispersing by ultrasonic treatment is simple and preferable.

  If the boron nitride nanotube derivative dispersion liquid of the present invention is used, a molded / processed product using the boron nitride nanotube derivative as a material can be easily obtained. For example, a boron nitride nanotube derivative dispersion is cast on a substrate or belt-like material, and heated to evaporate the solvent, thereby easily and efficiently producing a film-like material made of the boron nitride nanotube derivative. be able to.

Next, a method for producing the boron nitride nanotube derivative of the present invention will be described.
One method for producing the boron nitride nanotube derivative of the present invention is to treat the boron nitride nanotube with a hydrogen peroxide solution and then treat with a silylating agent.

  Regarding the treatment with the hydrogen peroxide solution, specifically, the boron nitride nanotube is 3 to 70% by mass of hydrogen peroxide solution, or 3 to 70% by mass of hydrogen peroxide and 10% of iron (II) ions. It is preferable to treat with a mixed composition solution containing ˜1000 mass ppm, and the concentration of hydrogen peroxide at that time is preferably 5 to 60 mass%, more preferably 30 to 55 mass%. In addition, the iron (II) ion concentration in the mixed composition solution containing hydrogen peroxide and iron (II) ions is more preferably 50 to 500 ppm by mass, and particularly preferably 100 to 300 ppm by mass. preferable.

  In the treatment with the hydrogen peroxide solution, a hydrogen peroxide solution is preferable as the hydrogen peroxide solution. However, the hydrogen peroxide solution must be added to at least one organic solvent selected from the group consisting of methanol, ethanol, ethylene glycol, acetone, acetic acid, and the like. A solution in which hydrogen oxide is dissolved may be used, or a solution in which hydrogen peroxide is dissolved in a solvent in which the organic solvent and water are mixed may be used. As the hydrogen peroxide solution, a commercially available aqueous hydrogen peroxide solution can be used, or it can be appropriately diluted with water or the like. As iron (II) ions, those obtained by adding ordinary iron (II) salts such as iron sulfate, iron chloride, iron acetate, and iron nitrate to a hydrogen peroxide solution can be preferably used.

  In the treatment with the hydrogen peroxide solution, when the reaction treatment is performed with the hydrogen peroxide solution or the mixed composition solution of hydrogen peroxide and iron (II) ions, room temperature or the reaction is accelerated. In addition to heating to an appropriate temperature (30 to 100 ° C. or lower), it is also preferable to perform treatment while applying ultrasonic waves. In addition, various treatment conditions for controlling the degree of atomic composition on the surface of the boron nitride nanotube derivative and the treatment time, such as treatment with a high temperature (100 ° C. or higher) reaction under pressure, can be suitably applied.

  In the treatment with the hydrogen peroxide solution, the hydrogen peroxide solution in an amount exceeding twice the mass ratio or the mixed composition in an amount exceeding twice the mass ratio with respect to the boron nitride nanotube as a raw material. It is preferable to treat the boron nitride nanotubes by adding a physical solution. When the amount of the hydrogen peroxide solution or the mixed composition solution is less than this amount, the introduction of silicon atoms into the boron nitride nanotubes by subsequent treatment with a silylating agent does not proceed smoothly, and the resulting nitriding The dispersibility of the boron nanotube derivative in the solvent may be insufficient, which is not preferable.

Next, treatment with a silylating agent in the method for producing a boron nitride nanotube derivative of the present invention will be described.
In the production method of the present invention, the treatment with a silylating agent (hereinafter sometimes abbreviated as “silylation treatment”) includes boron nitride nanotubes treated with a hydrogen peroxide solution as described above (hereinafter referred to as “boron nitride”). Are preferably treated with a silyl etherification method / condition using a known silylating agent. Specifically, the following (A) to (E) A processing method can be exemplified.

(A) In the presence of a base such as triethylamine, a chlorosilane compound (Greene and Wuts, Protective Groups in Organic Synthesis, Third Edition; John Wiley & Sons: New York, 1999, P. 113-148, 237- 241, 273-276, 428-431) and treating boron nitride nanotube oxide under silyl etherification conditions.
(B) A method of treating boron nitride nanotube oxide under silyl etherification conditions (eg, J. Am. Chem. Soc., 1963, 85 P.2497-2507) using hexamethyldisilazane as a silylating agent.
(C) Under silyl etherification conditions (for example, Biochem. Biophys. Res. Commun., 1968, 31, P.616-622) using N, O-bis (trimethylsilyl) trifluoroacetamide or the like as a silylating agent. To treat boron nitride nanotube oxide.
(D) A method of treating boron nitride nanotube oxide under silyl etherification conditions (Synthesis, 1981, P. 807-809) using N, N′-bis (trimethylsilyl) urea or the like as a silylating agent.
(E) A method of treating boron nitride nanotube oxide under silyl etherification conditions (Tetrahedron Lett., 1991, P.7159-7160) using tert-butyldimethylsilanol or the like as a silylating agent.

  As the chlorosilane compound in the above (A), trimethylsilyl chloride, triethylsilyl chloride, dimethylhydrosilyl chloride, dimethylvinylsilyl chloride, methylvinylhydrosilyl chloride, dimethylphenylsilyl chloride, vinyltrichlorosilane, dimethyldichlorosilane, vinylmethyldisilane. One or more selected from the group consisting of chlorosilane, octylmethyldichlorosilane, and octadecylmethyldichlorosilane are preferred.

  In the silylation treatment in the production method of the present invention, commercially available silylating agents as described above may be used neat as they are, or may be appropriately diluted with an aprotic organic solvent or the like. .

  In the silylation treatment in the production method of the present invention, it is preferable to carry out the treatment while applying ultrasonic waves in addition to heating to room temperature or an appropriate temperature (30 to 100 ° C. or lower) in order to accelerate the reaction. In addition, various treatment conditions for controlling the degree of silicon atom amount of the boron nitride nanotube derivative and the treatment time, such as treatment with a high temperature (100 ° C. or higher) reaction under pressure, can be suitably applied.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the description of these examples.

<Average diameter, average length, and appearance of boron nitride nanotube and its derivatives>
More than 50 boron nitride nanotubes were observed with a transmission electron microscope (TEM), and the average diameter and length thereof were taken to obtain the average diameter and average length of the boron nitride nanotubes. The boron nitride nanotube derivative was also observed and measured in the same manner and photographed.

<Surface elemental composition of boron nitride nanotubes and their derivatives>
Using samples of boron nitride nanotubes and derivatives thereof, hard X-ray photoelectron spectroscopy was performed to analyze the surface elemental composition.

[Reference Example 1 Production of Boron Nitride Nanotubes]
Boron and a magnesium oxide were put into the crucible made from boron nitride by the molar ratio of 1: 1, and the crucible was heated at 1300 degreeC with the high frequency induction heating furnace. Boron and magnesium oxide reacted to form gaseous boron oxide (B ₂ O ₂ ) and magnesium vapor. This product was transferred to the reaction chamber with argon gas, and ammonia gas was introduced while maintaining the temperature at 1100 ° C. Boron oxide and ammonia reacted to form boron nitride. When 1.55 g of the mixture was fully heated and the by-product was evaporated, 310 mg of a white solid was obtained from the walls of the reaction chamber. Subsequently, the obtained white solid was washed with concentrated hydrochloric acid and washed with ion-exchanged water until neutral, and then dried at 60 ° C. under reduced pressure to obtain boron nitride nanotubes (hereinafter sometimes abbreviated as BNNT). The obtained BNNT was in the form of a tube having an average diameter of 27.6 nm and an average length of 2460 nm (2.46 μm). Table 1 shows the results of surface element composition analysis of the boron nitride nanotubes by hard X-ray photoelectron spectroscopy.

[Reference Example 2 Treatment of boron nitride nanotubes with hydrogen peroxide solution]
1 g of boron nitride nanotubes prepared in the same manner as in Reference Example 1 and 50 mL of a 50% aqueous hydrogen peroxide solution (Sigma Aldrich Japan Co., Ltd.) were placed in a flask and stirred at 50 ° C. for 24 hours under ultrasonic irradiation. Thereafter, the dispersion was centrifuged under the condition of 2000 rpm, and the obtained solid was separated and washed with 500 mL of ion exchange water and methanol to obtain 1 g of boron nitride nanotube oxide as white powder. Table 1 shows the results of surface element composition analysis of the boron nitride nanotube oxide by hard X-ray photoelectron spectroscopy.

[Example 1]
1 g of boron nitride nanotube oxide and 1.85 g of triethylamine prepared in the same manner as in Reference Example 2 and 30 ml of tetrahydrofuran were added to a 100 ml three-necked flask equipped with a thermometer, a stirrer, a reflux condenser and a dropping float. The mixture was stirred at 40 ° C. for 30 hours under sonic irradiation. Then, 1.9 g of trimethylsilyl chloride was added dropwise at 30 ° C. over 40 minutes. After completion of the dropwise addition, the mixture was stirred and reacted at room temperature for 4 hours while being irradiated with ultrasonic waves. Thereafter, the dispersion was centrifuged under the condition of 2000 rpm, and the obtained solid was separated and washed with 500 mL of ion-exchanged water and methanol to obtain 1 g of boron nitride nanotube derivative of white powder. FIG. 1 shows a transmission electron micrograph of the boron nitride nanotube derivative sample. The boron nitride nanotube derivative had an average diameter of 30.5 nm and an average length of 2200 nm (220 μm). As a result, it was confirmed that the one-dimensionality, size and aspect ratio of the boron nitride nanotube derivative substantially maintained the structure of the boron nitride nanotube before treatment. Table 1 shows the results of surface element composition analysis of boron nitride nanotube derivatives by hard X-ray photoelectron spectroscopy. As is apparent from Table 1, the boron nitride nanotube derivative has an increased absorption peak derived from silicon atoms compared to the boron nitride nanotube composition before and after the treatment, and about 2.4 atomic% of the surface composition is silicon. It was confirmed that

  Further, 0.1 parts by mass of the boron nitride nanotube derivative is added to each solvent (10 parts by mass) of benzene, toluene, γ-butyrolactone, hexane, and tetraethoxysilane, and a bath type ultrasonic dispersing machine is used. After carrying out a dispersion treatment for 20 seconds to prepare a boron nitride nanotube derivative dispersion, this was left at room temperature to observe and evaluate the dispersion state. The obtained dispersion maintained a stable dispersion state in any solvent system, and even when stored as it was for one week, the boron nitride nanotube derivative did not aggregate or precipitate due to phase separation.

[Comparative Example 1]
To each solvent (10 parts by mass) of benzene, toluene, γ-butyrolactone, hexane and tetraethoxysilane, 0.1 part by mass of boron nitride nanotubes prepared in the same manner as in Reference Example 1 was added, and a bath type was added. The treatment liquid that had been subjected to the dispersion treatment for 20 seconds with an ultrasonic disperser was allowed to stand at room temperature, and the dispersion state was observed and evaluated. It did not become a dispersion.

  According to the present invention, a boron nitride nanotube derivative having extremely good dispersibility in an organic solvent can be obtained. A dispersion can be produced using this boron nitride nanotube derivative. If this dispersion is used, the boron nitride nanotube derivative can be molded and used in many fields such as semiconductor materials.

Claims (7)

2 atomic% or more is Ri silicon der, boron nanotubes derivatives nitride having dispersibility in the solvent of the surface elemental composition. The solvent is selected from the group consisting of alcohols, amide solvents, halogenated hydrocarbons, esters, ketones, ethers, silicon compound solvents, aromatic hydrocarbons, and aliphatic hydrocarbons containing a chain and / or cyclic structure. The boron nitride nanotube derivative according to claim 1, wherein the boron nitride nanotube derivative is at least one kind . The boron nitride nanotube derivative according to claim 1 or 2, having an average diameter of 0.4 nm to 1 µm and an average length of 1 to 10 µm. A boron nitride nanotube derivative dispersion in which the boron nitride nanotube derivative according to any one of claims 1 to 3 is dispersed in a solvent . The solvent is selected from the group consisting of alcohols, amide solvents, halogenated hydrocarbons, esters, ketones, ethers, silicon compound solvents, aromatic hydrocarbons, and aliphatic hydrocarbons containing a chain and / or cyclic structure. The boron nitride nanotube derivative dispersion liquid according to claim 4, wherein the dispersion liquid is at least one kind. The boron nitride nanotubes were treated with a 3-70 mass% hydrogen peroxide solution or a mixed composition solution containing 3-70 mass% hydrogen peroxide and 10-1000 mass ppm of iron (II) ions, and further silylated The method for producing a boron nitride nanotube derivative according to any one of claims 1 to 3, wherein the treatment is performed with an agent . The process according to claim 6, wherein the treatment with the silylating agent uses a chlorosilane compound in the presence of a base.