JP6512574B2 - Aqueous dispersion of nanocarbon material using gemini surfactant as dispersant and method for producing the same - Google Patents

Description

  The present invention relates to an aqueous dispersion of a nanocarbon material, a method for producing the same, and a dispersant used therefor.

  Because of its excellent electrical properties, mechanical properties, optical properties, electrochemical properties, and antioxidant properties, nanocarbon materials such as carbon nanotubes and fullerenes have potential applications in various fields as potential nanotechnological materials. And commercialization has also started. For example, carbon nanotubes are applied in the electronic materials field because they have high conductivity, and fullerenes have high radical scavenging ability and active oxygen scavenging ability, and this property is noted from the viewpoint of skin care ingredients and cancer preventive effects. Application to cosmetics, medicines, etc. is expected.

  In order to sufficiently exhibit the characteristics with a smaller amount of nanocarbon substance and facilitate application to various applications, a dispersion liquid in which the nanocarbon substance is uniformly dispersed in a dispersion medium (water, organic solvent, etc.) Is required. However, nanocarbon materials tend to aggregate because of their nanosize, and dispersion in a simple dispersion medium is often difficult.

  Furthermore, although each carbon nanotube is a tube-shaped substance having a large aspect ratio, the carbon nanotubes aggregate in a state in which the tubes are entangled and exist as a massive powder. It was necessary to loosen it to the level of the book and disperse it so that the original characteristics would be exhibited. The fullerene has a spherical hollow structure in which a large number of carbon atoms are bound like a cage, and it can be handled only by a solvent having extremely low polarity and non-water solubility, and there have been major restrictions on its application development.

  The method of dispersing the nanocarbon material is roughly classified into two methods: a method of modifying and dispersing the nanocarbon material itself, and a method of dispersing using a dispersing agent such as a surfactant and a polymer compound.

  The method of modifying and dispersing the nanocarbon substance itself (patent documents 1 and 2) has a problem that the steric structure and physical properties originally possessed due to the chemical modification are impaired, and the unmodified nanocarbon It is not preferable when it is desired to use a substance.

  In the method of dispersing using a dispersing agent, for example, as a dispersing agent for carbon nanotubes, a polymer dispersing agent such as carboxymethyl cellulose and its salt (CMC) or a low molecular type surfactant such as sodium dodecyl sulfate sodium salt (SDS) An agent is used (Patent Document 3). However, low molecular type surfactants such as SDS are inferior in dispersion power and dispersion stability as compared with polymer dispersants, and carbon nanotubes can not exhibit the dispersing effect unless they are low in concentration, and can be dispersed in high concentration. Can not.

  Polymeric dispersants such as CMC have relatively dispersive power and are generally used as dispersants for carbon nanotubes, but when water is used as the dispersion medium, polymeric dispersants have solubility in water It is desirable to disperse carbon nanotubes in a state of being uniformly dissolved in advance, as it is not expensive and it is desirable to dissolve the polymer dispersant completely, while requiring a large amount of energy and time. It is necessary to increase the addition amount depending on the concentration, and the viscosity of the aqueous solution becomes high, which causes problems in the handling property.

  Also, in the carbon nanotube dispersion step, the wettability of the aqueous polymer dispersant solution to carbon nanotubes is low, so the carbon nanotubes adhere to the wall of the container, and when dispersing on a larger scale, there is a possibility that they can not be dispersed uniformly. As the mechanical dispersion force makes it difficult to aggregate or disperse carbon nanotubes at low energy, high energy must be added, and carbon nanotube defects tend to occur during the dispersion process, resulting in network formation. As a result, the conductivity, which is one of the unique characteristics of carbon nanotubes, may be lowered.

  Furthermore, when producing a transparent conductive film, which is an application example of carbon nanotubes, the aqueous dispersion of carbon nanotubes using a polymer dispersant has low wettability to a substrate such as a PET film, and repelling occurs. It is not easy to form a uniform coating film.

  Patent Document 4 discloses the stability of an aqueous dispersion of carbon nanotubes by using a compound having a structure of hydrophobic part-hydrophilic part-hydrophobic part in combination with a dispersing agent such as alkyl benzene sulfonate or alkyl ether sulfate. Technologies for enhancing the content have been proposed, but when the content of carbon nanotubes is large, there is a concern that the dispersion stability may decrease, and since the dispersant is a metal salt, it is difficult to apply to the field of electronic materials and usable. It is limited.

  On the other hand, as a method of preparing a fullerene water dispersion, there is a method of dissolving fullerene in an organic solvent such as toluene, adding water and simultaneously distilling off the organic solvent at the same time as ultrasonic irradiation (Patent Document 5). In addition to the concentration, there is a problem that it is difficult to completely remove the solvent.

  In addition, Patent Documents 6 and 7 propose a fullerene solubilizing composition which does not contain an organic solvent and uses an amphiphilic polymer compound such as polyvinyl pyrrolidone as a dispersant for fullerene. Patent Document 8 discloses a technology for stably dispersing carbon nanotubes, carbon nanocoils, carbon nanohorns, carbon nanofibers, fullerenes and the like by using a specific amphiphilic compound having a plurality of hydrophobic groups and hydrophilic groups. Proposed.

Japanese Patent Application Publication No. 2004-002156 JP-A-9-235235 Unexamined-Japanese-Patent No. 2010-254546 JP 2003-238126 A JP 2001-348214 A JP, 2005-060380, A WO 2003/099716 JP 2012-148970 A

  However, the dispersibility of the nanocarbon material is excellent, the handling property is good, and defects in the carbon nanotube after dispersion production can be reduced and network formation can be promoted, or the transparency and anti-oxidation of the high concentration fullerene dispersion There is a need for new dispersants having such performance, without dispersants that can improve the action. And about the above subjects, the same thing can be said to nano carbon materials generally represented by a carbon nanotube and fullerene.

  The present invention has been made in view of the circumstances as described above, and can uniformly disperse a nanocarbon substance in an aqueous solvent without impairing the handling property, and reduce defects and form a network of the nanocarbon substance after dispersion liquid production. It is an object of the present invention to provide a method for producing an aqueous dispersion of a nanocarbon material and an aqueous dispersion capable of promoting the

  In order to solve the above problems, the dispersant for the aqueous dispersion of nanocarbon material of the present invention has the following formula (I):

(Wherein, R ¹ represents an alkyl group having 1 to 22 carbon atoms, R ² represents an alkylene group having 1 to 22 carbon atoms, and R ³ represents an alkyl group having 1 to 22 carbon atoms, provided that R ¹ and R ² represent The carbon number of the R ¹ -CH-CH-R ² -moiety is selected to be 9 to 25. X and Y are both (1) X and Y are —O—SO ₃ M ¹ (M ¹ represents a counter cation of the hydrogen ions or salts.), (2) one of X and Y is -O- _{(AO) p} H a and the other is -O- _(AO) q H (AO carbon P represents an integer of 0 to 100, q represents an integer of 0 to 100, and the sum of p and q is 1 to 200). (3) Both X and Y are —OC (= O) —CH ₂ CH ₂ C (= O) OM ² (M ² is a hydrogen ion or a salt (4) X and Y are -OPO ₃ M ³ (M ³ is a hydrogen ion or a counter cation to be a salt) and the other is a hydroxyl group, (5) X and Y either is ^-NR 4 ^R 5 ^{R 6+} a of ^- and ^(R 4, ^{R 5} each independently represent a methyl group, an ethyl group, or a hydroxyethyl group, ^{R 6} is a methyl group, an ethyl group, Or A represents a halogen, and the other is a hydroxyl group, or (6) X and Y each represent -OC (= O) -CHR ⁷ -NR ⁸ R ⁹ · HX (R ⁷ represents hydrogen) An atom, an alkyl group having 1 to 4 carbon atoms, an alkylthio alkyl group having 1 to 4 carbon atoms, a thiol-containing alkyl group having a thiol group bonded to an alkyl group having 1 to 3 carbon atoms, a phenyl group, 1 to 3 carbon atoms Having a primary or secondary hydroxy group Rokishiarukiru group, or a hydroxy phenyl group .R ⁸ and R ⁹ are each independently a hydrogen atom, .X showing a methyl group, or an ethyl group is shown.) The counter anion a salt .Z is -O -C (= O)-, -C (= O) -O-, -NH-C (= O)-, or -O- is represented.

  The aqueous dispersion of the nanocarbon material of the present invention contains the dispersant represented by the formula (I) and the nanocarbon material.

  The method for producing an aqueous dispersion of a nanocarbon material of the present invention is characterized in that the dispersant represented by Formula (I) and the nanocarbon material are mixed and dispersed in an aqueous solvent.

  According to the present invention, carbon nanotubes are excellent in the dispersibility of nanocarbon substances such as carbon nanotubes and fullerenes, and carbon nanotubes can be dispersed with a general dispersant even if the amount of nanocarbon substances such as carbon nanotubes can not be dispersed. It is possible to effectively disperse nano carbon materials such as and fullerenes without aggregation and sedimentation. In addition, it is possible to obtain an aqueous dispersion of a nanocarbon material having a low viscosity and a high concentration, which is excellent in handling properties, and has high wettability to the nanocarbon material of the dispersant aqueous solution, and nanocarbon on wall surfaces etc. The adhesion of substances can also be suppressed. Furthermore, since high concentration dispersion with low energy is possible, an aqueous dispersion of a nanocarbon material having few defects, a feature to form a good network, and a feature to improve transparency and antioxidative action can be obtained.

Optical microscope immediately after and one day after dispersion of aqueous dispersion of carbon nanotubes of Examples and Comparative Examples (Dispersant concentration 0.1 mass%, SW-CNT concentration 0.1 mass%, ultrasonic dispersion condition 10 W, 10 minutes) It is a photograph. Optical micrograph of 1 day after dispersion of aqueous dispersion of carbon nanotubes of Examples and Comparative Examples (Dispersant concentration 0.1 mass%, SW-CNT concentration 0.1 mass%, ultrasonic dispersion condition 30 W, 10 minutes) It is. Optical microscopes immediately after and one day after dispersion of aqueous dispersion of carbon nanotubes of Examples and Comparative Examples (Dispersant concentration 0.1 mass%, DW-CNT concentration 0.1 mass%, ultrasonic dispersion condition 10 W, 10 minutes) It is a photograph. Optical microscope immediately after and one day after dispersion of aqueous dispersion of carbon nanotubes of Examples and Comparative Examples (Dispersant concentration 0.1 mass%, MW-CNT concentration 0.1 mass%, ultrasonic dispersion condition 10 W, 10 minutes) It is a photograph. Optical micrograph of 1 day after dispersion of aqueous dispersion of carbon nanotubes of Examples and Comparative Examples (Dispersant concentration 0.1 mass%, MW-CNT concentration 0.1 mass%, ultrasonic dispersion condition 30 W, 10 minutes) It is. Optical microscopes immediately after and one day after dispersion of aqueous dispersions of carbon nanotubes of Examples and Comparative Examples (Dispersant concentration: 1.0% by mass, MW-CNT concentration: 1.0% by mass, ultrasonic dispersion condition: 10 W, 10 minutes) It is a photograph. Optical microscope immediately after and one day after dispersion of aqueous dispersion of carbon nanotubes of Examples and Comparative Examples (Dispersant concentration 1.0 mass%, MW-CNT concentration 1.0 mass%, ultrasonic dispersion condition 30 W, 10 minutes) It is a photograph. Aqueous dispersion of fullerene of Example (Dispersant 1) (Dispersant concentration: 1.0% by mass, fullerene concentration: 1.0% by mass, thin film swirl type high-speed mixer dispersion conditions: circumferential speed 40 m / s, 60 seconds × 5 times ) After dispersion (visual observation, optical microscope). Aqueous dispersion of fullerene of Example (Dispersant 3) (Dispersant concentration: 1.0% by mass, fullerene concentration: 1.0% by mass, thin film swirl type high-speed mixer Dispersion conditions: circumferential speed 40 m / s, 60 seconds × 5 times ) After dispersion (visual observation, optical microscope). Aqueous dispersion of fullerene of Comparative Example (Dispersant 10) (Dispersant concentration 1.0% by mass, Fullerene concentration 1.0% by mass, thin film swirl type high speed mixer Dispersion conditions: circumferential speed 40 m / s, 60 seconds × 5 times ) After dispersion (visual observation, optical microscope). Aqueous dispersion of fullerene of Comparative Example (Dispersant 12) (Dispersant concentration: 1.0% by mass, fullerene concentration: 1.0% by mass, thin film swirl type high-speed mixer Dispersion conditions: circumferential speed 40 m / s, 60 seconds × 5 times ) After dispersion (visual observation, optical microscope). Aqueous dispersion of fullerene of Comparative Example (Dispersant 13) (Dispersant concentration: 1.0% by mass, fullerene concentration: 1.0% by mass, thin film swirl type high-speed mixer Dispersion conditions: circumferential speed 40 m / s, 60 seconds x 5 times ) After dispersion (visual observation, optical microscope). Aqueous dispersion of fullerene of Comparative Example (Dispersant 14) (Dispersant concentration: 1.0% by mass, fullerene concentration: 1.0% by mass, thin film swirl type high-speed mixer Dispersion conditions: circumferential speed 40 m / s, 60 seconds × 5 times ) After dispersion (visual observation, optical microscope). Scanning electron microscope of dried sample of aqueous dispersion of carbon nanotubes of Example and Comparative Example (Dispersant concentration 0.1 mass%, MW-CNT concentration 0.1 mass%, ultrasonic dispersion condition 10 W, 10 minutes) SEM) It is a photograph. The numbers below the photo show the magnification. Scanning electron microscope of dried sample of aqueous dispersion of carbon nanotubes of Example and Comparative Example (Dispersant concentration 0.1 mass%, MW-CNT concentration 0.1 mass%, ultrasonic dispersion condition 30 W, 10 minutes) SEM) It is a photograph. The numbers below the photo show the magnification.

  Hereinafter, the present invention will be described in detail.

  In the present invention, the gemini surfactant represented by the above formula (I) is used as a dispersant. This gemini surfactant uses, as a raw material, a naturally-occurring unsaturated fatty acid, unsaturated aliphatic alcohol, etc., which are easily obtained industrially, and fatty groups at functional groups such as carboxyl groups at the terminals and alkoxides derived from alcohol. Hydrocarbon chains such as alkyl esters, alkylamides, alkylethers, etc. by introducing alkyl group-containing compounds such as aliphatic alcohols, aliphatic amines and halogenated alkyls, unsaturated fatty acids, unsaturated aliphatic alcohols, etc. The compound has a two-chain hydrophobic group with a hydrocarbon chain derived from the raw material of the above, and the double bond site of the raw material becomes a linking group as referred to in the gemini surfactant and is obtained by oxidizing the double bond part A sulfuric acid ester or a salt thereof, an alkylene oxide, a succinic acid monoester or a salt thereof, an ammonium salt, a phosphoric acid ester, or the like on at least one of the two hydroxyl groups And a molecular structure of gemini with Le or two hydrophilic groups introduced a salt thereof or amino acids.

In formula (I), R ¹ represents an alkyl group having 1 to 22 carbon atoms.

As the alkyl group R ¹ , for example, methyl group, ethyl group, n-propyl group, n-butyl group, n-pentyl group, n-hexyl group, n-heptyl group, n-octyl group, n-nonyl group, n-decyl group, n-undecyl group, n-dodecyl group, n-tridecyl group, n-tetradecyl group, n-pentadecyl group, n-hexadecyl group, n-heptadecyl group, n-octadecyl group, n-nonadecyl group, n-icosyl group, n-henicosyl group, n-docosyl group etc. are mentioned.

  Among these, n-hexyl group, n-heptyl group, n-octyl group, n-nonyl group, n-decyl group, n-undecyl group, n-dodecyl group, n-tridecyl group, n-tetradecyl group, n -Nonadecyl group is preferred.

In formula (I), R ² represents an alkylene group having 1 to 22 carbon atoms.

As the alkylene group R ² , for example, a methylene group, an ethylene group, an n-propylene group, an n-butylene group, an n-pentylene group, an n-hexylene group, an n-heptylene group, an n-octylene group, an n-nonylene group , N-decylene group, n-undecylene group, n-dodecylene group, n-tridecylene group, n-tetradecylene group, n-pentadecylene group, n-hexadecylene group, n-heptadecylene group, n-octadecylene group, n-nonadecylene group , N-icosilene group, n-henicosilene group, n-docosylene group and the like.

  Among these, methylene group, ethylene group, n-propylene group, n-butylene group, n-pentylene group, n-hexylene group, n-heptylene group, n-octylene group, n-nonylene group, n-decylene group, n-undecylene group, n-dodecylene group, n-tridecylene group and n-pentadecylene group are preferable, and methylene group, ethylene group, n-propylene group, n-butylene group, n-pentylene group, n-hexylene group, n- The heptylene group, the n-nonylene group, the n-decylene group and the n-undecylene group are more preferable.

In formula (I), R ¹ and R ² are selected such that the carbon number of the —R ¹ —CH—CH—R ² moiety is 9 to 25.

As the -R ¹ -CH-CH-R ² moiety, for example,-(CH ₂ ) ₂ -CH-CH- (CH ₂ ) ₄ CH ₃ ,-(CH ₂ ) ₇ -CH-CH-CH ₃ ,- _{CH 2 -CH-CH- (CH 2} ) 7 -CH 3, - (CH 2) 2 -CH-CH- (CH 2) 6 CH 3, - (CH 2) 3 -CH-CH- (CH 2) _{5 CH 3, - (CH 2} ) 7 -CH-CH- (CH 2) 2 CH 3, - (CH 2) 2 -CH-CH- (CH 2) 8 CH 3, - (CH 2) 3 -CH -CH- (CH ₂ ) ₇ CH ₃ ,-(CH ₂ ) ₇ -CH-CH- (CH ₂ ) ₃ CH ₃ ,-(CH ₂ ) ₄ -CH-CH- (CH ₂ ) ₇ CH ₃ ,- (CH ₂ ) ₇ -CH-CH- (CH ₂ ) ₄ CH ₃ , -CH ₂ -CH-CH- (CH ₂ ) _{1 1} CH ₃ ,-(CH ₂ ) ₅ -CH-CH- (CH ₂ ) ₇ CH ₃ ,-(CH ₂ ) ₇ -CH-CH- (CH ₂ ) ₅ CH ₃ ,-(CH ₂ ) ₅ -CH _{-CH- (CH 2) 8 CH 3} , - (CH 2) 6 -CH-CH- (CH 2) 7 CH 3, - (CH 2) 7 -CH-CH- (CH 2) 6 CH 3, - _{CH 2 -CH-CH- (CH 2} ) 13 CH 3, - (CH 2) 2 -CH-CH- (CH 2) 12 CH 3, - (CH 2) 4 -CH-CH- (CH 2) 10 _{CH 3, - (CH 2)} 5 -CH-CH- (CH 2) 9 CH 3, - (CH 2) 6 -CH-CH- (CH 2) 8 CH 3, - (CH 2) 7 -CH- _{CH- (CH 2) 7 CH 3} , - (CH 2) 9 -CH-CH- (CH 2) 5 CH 3, -(CH ₂ ) ₇ -CH-CH- (CH ₂ ) ₈ CH ₃ ,-(CH ₂ ) ₉ -CH-CH- (CH ₂ ) ₇ CH ₃ ,-(CH ₂ ) ₁₀ -CH-CH- ( CH ₂ ) ₇ CH ₃ ,-(CH ₂ ) ₁₁ -CH-CH- (CH ₂ ) ₇ CH ₃ ,-(CH ₂ ) ₈ -CH-CH- (CH ₂ ) ₁₁ CH ₃ ,-(CH ₂ ) _{12 -CH-CH- (CH 2)} 7 CH 3, - (CH 2) 13 -CH-CH- (CH 2) 7 CH 3, - (CH 2) 3 -CH-CH- (CH 2) 18 CH _{3, - (CH 2) 15} -CH-CH- (CH 2) 6 CH 3, - (CH 2) 15 -CH-CH- (CH 2) 7 CH 3 and the like.

Among these, -CH ₂ -CH-CH- (CH ₂ ) ₇ -CH ₃ ,-(CH ₂ ) ₂ -CH-CH- (CH ₂ ) ₆ CH ₃ ,-(CH ₂ ) ₃ -CH-CH -(CH ₂ ) ₅ CH ₃ ,-(CH ₂ ) ₂ -CH-CH- (CH ₂ ) ₈ CH ₃ ,-(CH ₂ ) ₃ -CH-CH- (CH ₂ ) ₇ CH ₃ ,-(CH ₂ ) _{2) 4 -CH-CH- (CH} 2) 7 CH 3, -CH 2 -CH-CH- (CH 2) 11 CH 3, - (CH 2) 5 -CH-CH- (CH 2) 7 CH 3 ,-(CH ₂ ) ₇ -CH-CH- (CH ₂ ) ₅ CH ₃ ,-(CH ₂ ) ₅ -CH-CH- (CH ₂ ) ₈ CH ₃ ,-(CH ₂ ) ₆ -CH-CH- _{(CH 2) 7 CH 3,} - (CH 2) 7 -CH-CH- (CH 2) 6 CH 3, -C _{2 -CH-CH- (CH 2)} 13 CH 3, - (CH 2) 2 -CH-CH- (CH 2) 12 CH 3, - (CH 2) 4 -CH-CH- (CH 2) 10 CH ₃ ,-(CH ₂ ) ₅ -CH-CH- (CH ₂ ) ₉ CH ₃ ,-(CH ₂ ) ₆ -CH-CH- (CH ₂ ) ₈ CH ₃ ,-(CH ₂ ) ₇ -CH-CH -(CH ₂ ) ₇ CH ₃ ,-(CH ₂ ) ₉ -CH-CH- (CH ₂ ) ₅ CH ₃ ,-(CH ₂ ) ₇ -CH-CH- (CH ₂ ) ₈ CH ₃ ,-(CH ₂ ) ₂ ) ₉ -CH-CH- (CH ₂ ) ₇ CH ₃ ,-(CH ₂ ) ₁₀ -CH-CH- (CH ₂ ) ₇ CH ₃ ,-(CH ₂ ) ₁₁ -CH-CH- (CH ₂ ) ₇ CH ₃ is preferred.

In formula (I), R ³ represents a linear or branched alkyl group having 1 to 22 carbon atoms.

  As the alkyl group, for example, methyl group, ethyl group, n-propyl group, n-butyl group, n-pentyl group, n-hexyl group, n-heptyl group, n-octyl group, n-nonyl group, n- Decyl group, n-undecyl group, n-dodecyl group, n-tridecyl group, n-tetradecyl group, n-pentadecyl group, n-hexadecyl group, n-heptadecyl group, n-octadecyl group, n-nonadecyl group, n- Examples include icosyl group, n-hemicosyl group, n-docosyl group, isopropyl group, isobutyl group, sec-butyl group, tert-butyl group, isopentyl group, neopentyl group, tert-pentyl group, 2-ethylhexyl group and the like.

  Among these, n-butyl group, n-hexyl group, n-heptyl group, n-octyl group, n-nonyl group, n-decyl group, n-dodecyl group, n-tetradecyl group, n-hexadecyl group, n -Octadecyl group, n-docosyl group, isopropyl group, isobutyl group, 2-ethylhexyl group are preferable.

  In formula (I), X and Y each represent any one of the groups (1) to (5).

In the above (1), X and Y are both of X and Y is _{^{-O-SO 3 M 1 (M}} 1 represents a counter cation comprising hydrogen ions or salts.) Is.

Examples of the counter cation to be a salt of M ¹ include alkali metal ions, group 2 element ions, transition element ions, group 12 element ions, aluminum ions, indium ions, tin ions, lead ions, ammonium ions and the like. .

Examples of the alkali metal ion of M ¹ include lithium ion, sodium ion, potassium ion and the like.

Examples of the group 2 element ion of M ¹ include magnesium ion, calcium ion, strontium ion, barium ion and the like.

Examples of transition element ions of M ¹ include yttrium ion, zirconium ion, hafnium ion, manganese ion, iron ion, cobalt ion, nickel ion, copper ion, silver ion and the like.

Examples of the group 12 element ion of M ¹ include zinc ion, cadmium ion and the like.

Examples of the ammonium ion of M ¹ include ammonium ions derived from aliphatic amines such as ammonia, hydroxyamine, monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine and triethylamine, pyrrolidine, piperidine, pyridine, piperazine, pyrrole and the like. Examples thereof include ammonium ions derived from cyclic amines and ammonium ions derived from alkanolamines such as monoethanolamine, diethanolamine and triethanolamine.

  Among the above counter cations, sodium ion and potassium ion are preferable.

In the above (2), in X and Y, one of X and Y is -O- (AO) _pH , and the other is -O- (AO) _qH (AO is an alkylene oxide having 2 to 3 carbon atoms) P represents an integer of 0 to 100, q represents an integer of 0 to 100, and the sum of p and q is 1 to 200).

  As the alkylene oxide of AO, for example, ethylene oxide and propylene oxide are used, and these can be used in combination. When ethylene oxide and propylene oxide are used in combination, the polyoxyalkylene chain may be one obtained by addition polymerization of ethylene oxide and propylene oxide at random, or one obtained by addition polymerization in block form.

  The addition polymerization mole number of the alkylene oxide per hydroxyl group of the dispersant represented by the formula (I) is 100 mol or less, preferably 50 mol or less, and the total of the addition polymerization of the alkylene oxide to two hydroxyl groups. The number of moles is 1 to 200 moles, preferably 1 to 100 moles.

  The polyoxyalkylene chain formed by the addition polymerization of the alkylene oxide to each hydroxyl group may be the same or different in the number of moles of addition of the alkylene oxide, and the different alkylene oxides are formed by addition polymerization. It may be done.

In the above (3), X and Y each represents a counter cation in which both X and Y are —OC (= O) —CH ₂ CH ₂ C (= O) OM ² (M ² is a hydrogen ion or a salt) ).

Examples of the counter cation to be a salt of M ² include alkali metal ions, group 2 element ions, transition element ions, group 12 element ions, aluminum ions, indium ions, tin ions, lead ions, ammonium ions and the like. . As these counter cations, those exemplified for the above M ¹ can be used.

  Among the above counter cations, lithium ion, sodium ion, potassium ion and ammonium ion derived from ammonia, monoethanolamine, diethanolamine, triethanolamine and the like are preferable.

In the above (4), X and Y, one of X and Y is -OPO ^{₃ M} ₃ (M ₃ in. Represents a counter cation becomes hydrogen ions or salt) other is a hydroxyl group.

Examples of the counter cation to be a salt of M ³ include inorganic cations such as sodium ion, potassium ion, lithium ion, ammonium ion, triethanol ammonium ion, and diethanol ammonium ion, and organic ammonium ions.

In the above (5), X and Y, one of X and Y is ^-NR 4 ^R 5 ^{R 6+} A ^- a ^(R 4, ^{R 5} are each independently a methyl group, an ethyl group, or a hydroxyethyl group And R ⁶ represents a methyl group, an ethyl group or a dihydroxypropyl group, and A represents a halogen.) The other is a hydroxyl group.

  Examples of the halogen of A include chlorine, bromine, iodine and fluorine.

In the above (6), each of X and Y in the above (6) is —OC () O) —CHR ⁷ —NR ⁸ R ⁹ · HX (R ⁷ is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, Alkylthio alkyl group having 1 to 4 carbon atoms, thiol-containing alkyl group having a thiol group bonded to an alkyl group having 1 to 3 carbon atoms, phenyl group, hydroxyalkyl group having a primary or secondary hydroxy group having 1 to 3 carbon atoms And R ⁸ and R ⁹ each independently represent a hydrogen atom, a methyl group or an ethyl group, and X represents a counter anion to be a salt).

When R ⁷ is other than a hydrogen atom, the carbon atom bonded to R ⁷ is an asymmetric carbon center and represents a D-form, an L-form, or a D, L-form mixture.

The alkyl group having 1 to 4 carbon atoms of R ⁷ is linear or branched and, for example, methyl group, ethyl group, n-propyl group, n-butyl group, isobutyl group, sec-butyl group, tert- A butyl group etc. are mentioned.

The alkylthio alkyl group having 1 to 4 carbon atoms for R ⁷ is linear or branched, and examples thereof include —CH ₂ CH ₂ —S—CH _{3 and the} like.

The thiol-containing alkyl group in which a thiol group is bonded to an alkyl group having 1 to 3 carbon atoms of R ⁷ has a linear or branched alkyl group, and examples thereof include —CH ₂ SH and the like.

As a hydroxyalkyl group having a primary or secondary hydroxy group and having a carbon number of 1 to 3 and a primary or secondary hydroxy group of R ⁷ , for example, hydroxy group, n-hydroxyethyl group, 1-hydroxyethyl group, n-hydroxypropyl group etc. may be mentioned Be

R ⁸ and R ⁹ are preferably a combination of hydrogen atoms, a combination of hydrogen atoms and methyl groups, or a combination of methyl groups.

  Examples of the counter anion X to be a salt include halide ion, carboxylate ion, hydroxide ion, phosphate ion, nitrate ion, sulfate ion and the like.

  As a halide ion, a chloride ion, a bromide ion, a fluoride ion, an iodide ion etc. are mentioned, for example.

  Examples of carboxylic acid ions include C 1-4 monocarboxylic acid ions, dicarboxylic acid ions (including hydroxycarboxylic acid ions), hydroxycyclohexanecarboxylic acid ions, and aromatic carboxylic acid ions. Specifically, for example, formate ion, acetate ion, propionate ion, maleate ion, malate ion, succinate ion, glycolate ion, lactate ion, tartrate ion, 1,3,4,5-tetrahydroxycyclohexane Examples thereof include carboxylic acid (quinic acid) ion, benzoic acid ion, and pyrrolidone carboxylic acid ion.

  The dispersant represented by the formula (I) having the above constitution can be produced, for example, by the following method (JP-A-2009-007340, JP-A-2010-037308, JP-A-2010-070467) , JP-A-2010-138119, JP-A-2010-138120, JP-A-2010-229223, JP-A-2011-132418, JP-A-2011-157354, JP-A-2011-190184. JP 2011-236347 A, JP 2012-062246 A).

  First, a dihydroxy compound in which the moiety XY corresponding to the formula (I) is a hydroxyl group, for example, dihydroxy fatty acid alkyl ester, (dihydroxy alkyl) fatty acid ester, dihydroxy fatty acid alkylamide, (dihydroxy alkyl) alkyl ether is synthesized.

  Generally, unsaturated fatty acid alkyl ester which is a reaction product of unsaturated fatty acid having one double bond and aliphatic alcohol, alkenyl fatty acid ester which is a reaction product of unsaturated fatty alcohol having one double bond and fatty acid Unsaturated fatty acid alkylamide which is an amide of unsaturated fatty acid having one double bond and aliphatic amine, alkenyl alkyl ether which is an etherified product of unsaturated aliphatic alcohol having one double bond and halogenated alkyl, etc. Is reacted with an organic peroxide obtained from hydrogen peroxide and an organic acid such as formic acid to oxidize a double bond, allowed to react with a base such as sodium carbonate or potassium carbonate, and introduced a hydroxyl group. Dihydroxy fatty acid alkyl ester, (dihydroxy alkyl) fatty acid ester, dihydroxy fat Acid alkylamides, dihydroxy compounds such as (dihydroxy) alkyl ether is synthesized.

  Alternatively, the unsaturated fatty acid is first reacted with an organic peroxide obtained from hydrogen peroxide and an organic acid such as formic acid to oxidize a double bond, and a base such as sodium hydroxide or potassium carbonate is allowed to react with the hydroxyl group. Is synthesized to introduce dihydroxy fatty acid, and this dihydroxy fatty acid is subjected to an ester synthesis reaction with an aliphatic alcohol under acid catalyst or alkali catalyst, or alternatively, this dihydroxy fatty acid and aliphatic amine are reacted with dicyclohexyl carbondiimide (DCC) , Diisopropylcarbodiimide (DIPC), N-Ethyl-N'-3-Dimethylaminopropylcarbodiimide and its hydrochloride salt, Benzotriazol-1-yl-tris (dimethylamino) phosphonium hexafluorophosphate salt, Condensation with diphenylphosphoryl azide, etc. Agents or these Condensation using an additive such as N-hydroxysuccinimide, 1-hydroxybenzotriazole (HOBt) or 3-hydroxy-4-oxo-3,4-dihydro-1,2,3-benzotriazine together with the It is also possible to form an amide bond to obtain a dihydroxy compound.

The compounds in which X and Y in the formula (I) are (1) can be obtained by reacting a sulfur trioxide pyridine complex with the hydroxyl group of the above dihydroxy compound. Furthermore, when M ¹ is changed to a salt from hydrogen ion to a salt, butanol is added to the obtained compound, and the corresponding alkali metal, group 2 element, transition element ion, group 12 element ion, aluminum ion, It can be obtained by neutralization reaction with hydroxides such as indium ions, tin ions, lead ions and the like and amines and washing with water. Thereafter, the crystals obtained by distilling off the organic layer may be purified by recrystallization etc. using a solvent such as methanol, ethanol, butanol, acetonitrile or a mixed solvent thereof as necessary.

  The compounds in which X and Y in the formula (I) are (2) can be obtained by the addition polymerization of an alkylene oxide such as ethylene oxide or propylene oxide to the hydroxyl group of the dihydroxy compound.

  The compounds in which X and Y in the formula (I) are (3) can be obtained by reacting the above dihydroxy compound with succinic anhydride.

Furthermore, when M ² is changed from a hydrogen ion to a counter cation to be a salt, for example, the obtained compound is mixed with a corresponding alkali metal, a group 2 element, a transition element ion, It can be obtained by neutralization reaction with a hydroxide of group 12 element ion, aluminum ion, indium ion, tin ion, lead ion or the like, an amine or the like.

The compounds of the formula (I) wherein X and Y are (4) react the polyhydroxy acid with the above dihydroxy compound in an organic solvent to introduce a phosphate group and a hydroxyl group adjacent to each other at the open position of the double bond. It can be obtained by Further, when M ¹ is changed from hydrogen ion to a counter cation to be a salt, it can be obtained by neutralizing the obtained compound by adding an amine or an alkali and washing with water. Alternatively, purification may be performed by column chromatography using silica gel as a stationary phase and chloroform / methanol mixed solvent as a mobile phase.

  The compounds in which X and Y in the formula (I) are (5) can be obtained by reacting an unsaturated fatty acid having 10 to 26 carbon atoms having one double bond with an alkylamine having 1 to 20 carbon atoms. Once the double bond portion of the saturated fatty acid alkylamide is epoxidized, the secondary amine is reacted to react the N-alkyl (or N-hydroxyalkyl) aminohydroxy fatty acid alkylamide in which the amino group and the hydroxyl group are introduced adjacently; It can be obtained by the reaction with a halogenated alkyl (including one having a hydroxyl group).

Compounds in which X and Y in the formula (I) are (6) are the above dihydroxy compounds and HOC (= O) -CHR ⁷ -NR ⁸ R ⁹ (R ^{7 to} R ⁹ have the same meanings as described above). The amino acid can be obtained by ester synthesis reaction with an N-protected N-protected in the presence of a catalyst followed by deprotection. When an amino acid having a thiol group or a hydroxy group is used, the thiol group or the hydroxy group is also protected and used in the reaction.

  For example, in an organic solvent such as toluene, chloroform, dichloromethane, hexane, heptane or the like, the dihydroxy fatty acid alkyl ester as the above dihydroxy compound and 2 to 5 times mol equivalent of N-protected amino acid, 2 to 5 times mol equivalent 1-ethyl-3 (3-dimethylaminopropyl) carbodiimide hydrochloride, in the presence of 0.01 to 2 times mol equivalent of 4-dimethylaminopyridine, and reacted at room temperature for 12 to 48 hours under a nitrogen atmosphere.

  Next, the organic layer is washed and extracted in the order of aqueous hydrochloric acid solution, aqueous sodium hydroxide solution and water, and then the organic layer is distilled off to obtain a gum, which is then deprotected. Deprotection can be carried out by methods known in the art. For example, when an N-Boc protected amino acid is used, 4N hydrochloric acid / ethyl acetate solution is added, reacted at room temperature for 0.5 to 6 hours, deprotected, concentrated, and purified to obtain X as chloride ion. A dispersant of formula (I) is obtained. When the counter anion X to be a salt is changed from chloride ion to another anion, it can be carried out by a conventionally known method such as ion exchange. For example, a compound in which X is a chloride ion, an inorganic acid or an organic acid corresponding to the anion of the target compound, and an equimolar amount of triethylamine with respect to a compound in which X is a chloride ion in water or an organic solvent React with a base such as or pyridine. Although the reaction temperature and the reaction time depend on the type of the raw material and the like, for example, the desired dispersant of the formula (I) can be obtained by reacting at room temperature for about one day.

Amino acids HOC (= O) -CHR ⁷ -NR ⁸ R ⁹ include glycine, N-methylglycine, N, N-dimethylglycine, amino acids having an alkyl group in the side chain, and amino acids having an alkylthioalkyl group in the side chain, Examples include an amino acid having a thiol-containing alkyl group in a side chain, an amino acid having a phenyl group in a side chain, an amino acid having a hydroxyalkyl group in a side chain, and an amino acid having a hydroxyphenyl group in a side chain. When R ⁷ is an amino acid other than a hydrogen atom, it may be D-form, L-form or a mixture of D, L-forms.

  Among them, amino acids which are industrially easy to obtain and which are not too hydrophobic because they are hydrophilic groups, and which do not have a sterically bulky structure are preferable. Examples of such amino acids include glycine, alanine, There may be mentioned valine, serine, threonine and cysteine.

  As the N-protecting group of the above amino acid, for example, tert-butoxycarbonyl group (Boc), benzyloxycarbonyl group (Z or Cbz), 9-fluorenylmethyloxycarbonyl group (Fmoc), 2,2,2- Examples include trichloroethoxycarbonyl group (Troc), allyloxycarbonyl group (Alloc) and the like. As a hydroxy-protecting group, for example, benzyl ether (Bzl), tertiary butyl (t-Bu), p-methoxybenzyl ether (PMB), methoxymethyl ether (MOM), silyl ether, tetrahydro Pyranyl ether group (THP) etc. are mentioned. As a protective group for a thiol group, for example, p-methoxybenzyl ether group (PMB), 4-methylbenzyl group, trityl group (Trt), acetamidomethyl group (Acm), tertiary butyl group (t-Bu), etc. It can be mentioned.

  Commercially available N-protected amino acids can be used. Alternatively, the amino acids obtained can be N-protected. For example, N-Boc protection can be performed as follows. The amino acid is dissolved in dioxane, aqueous solution of NaOH (2 eq.) And Boc anhydride (1.1 eq.) Is slowly added dropwise with vigorous stirring. After completion of the reaction, the reaction solution is concentrated to a certain extent to remove t-butanol, then the solution is acidified and extracted, the organic layer is concentrated, and crude crystals obtained are washed with ether to obtain N. -Boc amino acids can be used.

  The aqueous dispersion of the nanocarbon material of the present invention contains the dispersant represented by the formula (I) and the nanocarbon material.

Examples of the nanocarbon material used in the present invention include carbon nanotubes, carbon nanohorns, nanographene, fullerenes such as fullerene C ₆₀ , fullerene C _{70 and the} like. The nanocarbon material is a material having a nanosize shape consisting of one layer (graphene sheet) of a six-membered ring graphite structure formed by covalent bonding of carbon atoms, or a five-membered ring and six-membered ring formed by covalent bonding of carbon atoms It is a closed shell hollow substance consisting of

A carbon nanotube, which is a type of nanocarbon material, is a nanocarbon material in which a graphene sheet is rounded to have a cylindrical shape. The types include single-walled carbon nanotubes consisting of only one layer, double-walled carbon nanotubes consisting of two layers, and multi-walled carbon nanotubes having a structure in which carbon nanotubes are concentrically overlapped. The diameter may be approximately 1 to 100 nm, and the length may be approximately 1 nm to 10 μm. The method for producing carbon nanotubes is not particularly limited, and, for example, carbon arc discharge method, laser ablation method, chemical vapor deposition (CVD) method, direct injection thermal decomposition (DIPS) method, CoMoCAT ^(R) method, HiPco ^{The (R)} method, the super growth CVD method or the like can be used. The carbon nanohorn is a nanocarbon material in which the graphene sheet has a rounded shape like a carbon nanotube, but is not a straight cylindrical shape but a tube tip is closed to form a horn (corner). Nanographene is a nanosized graphene sheet itself, and is a thin film shaped nanocarbon material having a thickness of only 1 atom. A fullerene is a nanocarbon material having a spherical hollow structure in which a large number of carbon atoms are linked in a cage.

As the nanocarbon substance in the present invention, in addition to fullerenes, any substance having a nanosize formed of a graphene sheet can be used any of carbon nanotubes, carbon nanohorns and nanographene, and the shape, size, and production thereof The method is not particularly limited. In addition, all mixtures thereof can be used. The nanocarbon material in the present invention, a single-layer, two-layer, multi-layer carbon nanotube is preferably fullerene C _60.

  The use concentration of the dispersant represented by the formula (I) in the aqueous dispersion of nanocarbon material of the present invention is not particularly limited, but the availability, dispersion stability, etc. of the aqueous dispersion of nanocarbon material 10 to 2000% by mass is preferable, 30 to 1500% by mass is more preferable, and 80 to 1000% by mass is particularly preferable in view of the nano carbon material.

  The concentration of the nanocarbon material in the aqueous dispersion of the nanocarbon material of the present invention is not particularly limited, but considering the availability, dispersion stability, etc. of the aqueous dispersion of the nanocarbon material, 0.01 -20 mass% is preferable, and 0.1-5.0 mass% is more preferable.

  As the aqueous solvent in the aqueous dispersion of the nanocarbon material of the present invention, water can be used alone, but it is possible to use water alone, monohydric alcohol such as methanol, ethanol, propanol, isopropanol, butanol, ethylene glycol, propylene glycol, butane Dihydric alcohols such as diols, trihydric alcohols such as glycerin, ketones such as acetone, acids such as formic acid, acetic acid, propionic acid, cyclic ethers such as tetrahydrofuran, N-methylpyrrolidone, dimethylsulfoxide etc. You may use. Among these, water alone or an aqueous solvent containing water as a main component is preferable in consideration of handleability and environmental aspects.

  In addition, salts, pH adjusters, preservatives, chelating agents, surfactants and the like may be added to the aqueous dispersion of the nanocarbon material of the present invention as needed within the range that does not impair the effects of the present invention. It is also good.

  The method for producing the aqueous dispersion of the nanocarbon material of the present invention can be obtained by mixing the dispersant represented by the formula (I) and the nanocarbon material in an aqueous solvent and performing dispersion treatment.

  The method for dispersing the nanocarbon material in an aqueous solvent is not particularly limited, but ultrasonic dispersion treatment with an ultrasonic homogenizer etc., high speed stirring dispersion treatment with a stirring homogenizer, stirring dispersion with a thin film swirling high speed mixer etc. Treatment, pulverization dispersion treatment such as stirring mill using a grinding medium, dispersion treatment by jet mill, dispersion treatment by high shear agitation, etc. may be mentioned, but it is preferable to use a dispersion method which does not damage nano carbon material. In the case of dispersion processing using an ultrasonic homogenizer, it is preferable that the output is such an extent not accompanied by cutting of carbon nanotubes and the like. For example, the output is preferably 100 W or less, more preferably 50 W or less, and particularly preferably 10 to 30 W. The time for irradiating the ultrasonic wave may be appropriately set depending on the amount of carbon nanotubes, the type of the dispersing agent and the like, but for example, 1 minute to 3 hours is preferable, and 10 minutes to 1 hour is more preferable.

  The mixing method of the dispersing agent and the nanocarbon substance is also not particularly limited, and the dispersing treatment may be carried out after mixing the necessary amount, but the dilution solutions of the respective reagents may be prepared and mixed in advance.

  The dispersion obtained by ultrasonic treatment or stirring is precipitated by, for example, a bundle of carbon nanotubes, amorphous carbon, metal catalyst, etc. in the case of carbon nanotubes by a centrifugal separation method, and the aqueous dispersion of the nanocarbon substance of the present invention Can be collected as the supernatant. Alternatively, it is possible to filter the dispersion obtained by ultrasonic treatment or agitation treatment with a microfiltration membrane or the like to recover the aqueous dispersion of the nanocarbon material of the present invention as a filtrate.

  The viscosity of the aqueous dispersion of the nanocarbon material of the present invention can be determined by considering the availability of the aqueous dispersion of the nanocarbon material, for example, the uniformity of the coating film, the control of the film thickness, etc. The concentration range of the carbon substance is preferably 1 mPa · s to less than 10 mPa · s, and more preferably 1 mPa · s to less than 3 mPa · s.

  The aqueous dispersion of the nanocarbon material of the present invention is, for example, an aqueous dispersion of single-walled carbon nanotubes or double-walled carbon nanotubes as a transparent conductive material, and an aqueous dispersion of multi-walled carbon nanotubes as a paint, a composite material, a lubricant As a heat conductive medium, it can be expected to use an aqueous dispersion of fullerene in various fields such as magnetic recording media, electronic component materials, optical films, cosmetics, medicines and the like.

  For example, the conductivity of the surface of the substrate can be increased by coating the substrate and forming a film. According to the aqueous dispersion of the nanocarbon material of the present invention, since it is possible to loosen and disperse the bundle-like or massive nanocarbon material, it is possible to conduct conductivity by coating the dispersion to form a film, A thin film having high transparency and ultraviolet absorption ability can be obtained.

  In addition, according to the aqueous dispersion of fullerene of the present invention, it is possible to disperse the fullerene uniformly, so that the dispersion liquid is applied to a substrate to form a film, so that the ultraviolet absorbing performance and the antioxidative action can be obtained. High thin film is obtained.

The base material is not particularly limited, but resins such as thermoplastic resin, thermoplastic elastomer, thermosetting resin, and metals such as iron, steel, nickel, copper, zinc, lead, stainless steel, and other alloys And glass such as boric acid glass, Pyrex ^(R) , quartz glass and the like.

  The application method is not particularly limited, but application methods such as dip coating, spin coating, roll coating and spray coating can be selected according to the shape of the substrate and the like. The aqueous dispersion of the nanocarbon material of the present invention can be applied uniformly to the substrate with little coating unevenness using any coating method, but for example, if it is dip coating, adjustment of the pulling speed, spin coating In this case, it is possible to uniformly apply on various substrates by adjusting the dropping amount and the number of rotations, adjusting the coating thickness in the case of roll coating and adjusting the coating amount in the case of spray coating.

EXAMPLES Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to these examples.
[Preparation of Aqueous Dispersion of Carbon Nanotubes and Fullerene]
In Examples 1 to 28, the following Dispersants 1 to 8 were used as dispersants. Dispersants 1 to 8 were synthesized according to known methods.

  In Comparative Examples 1 to 34, the following dispersants 9 to 14 were used as dispersants.

Dispersant 9: Sodium dodecyl sulfate (SDS: manufactured by Kanto Chemical Co., product number: 37203)
-31)
Dispersant 10: Carboxymethylcellulose sodium (CMC: manufactured by WAKO, distributor
Code: 039-01335)
Dispersant 11: Acetylene glycol EO 30 mol adduct (manufactured by Shin-Etsu Chemical Co., Ltd.)
Dispersant 12: compound described in JP-A-2012-148970 Preparation Example 1 Dispersant 13: sodium deoxycholate (DOC: manufactured by TCI, product code: C031
6)
Dispersing agent 14: Polyvinyl pyrrolidone Molecular weight 40,000 (PVP: manufactured by TCI, product code: P0472)

  As carbon nanotubes, single-walled carbon nanotubes (SW-CNT: manufactured by Aldrich, product number: 704113), double-walled carbon nanotubes (DW-CNT: manufactured by Aldrich, product number: 637351), multi-walled carbon nanotubes (MW-CNT: WAKO Co., sales source code: 329-43383) was used.

As the fullerene, fullerene C ₆₀ (manufactured by TCI, product code: B1641) was used.

  In the evaluation of Tables 1 to 3, the dispersant and carbon nanotubes (SW-CNT, DW-CNT, MW-CNT) are used at the concentrations shown in Tables 1 to 3, and after the carbon nanotubes are added to the aqueous dispersant solution, Dispersion is carried out at 5 ° C., 10 W (low output) or 30 W (high output), 20 kHz, 10 minutes using an ultrasonic homogenizer (BRANSON, manufactured by Sonifier 250 D), and then an ultracentrifuge (manufactured by KUBOTA, 7780 II) The resultant was centrifuged at 10,000 rpm for 10 minutes, and the supernatant was used as an aqueous dispersion of carbon nanotubes (hereinafter, also referred to as "CNT dispersion"). Moreover, when performing evaluation one day after dispersion, centrifugation was performed again in the same manner, and the supernatant was used as a CNT dispersion.

  In the evaluation of Table 4, a dispersant and carbon nanotubes (MW-CNT) were used at the concentrations shown in Table 4, and after adding the carbon nanotubes to the dispersant aqueous solution, ultrasonic cleaner (ASONE VS-F 100, 50 kHz, 100 W) The ultrasound was irradiated for 5 minutes using. Thereafter, incubation was carried out at 25 ° C. for 24 hours. Filtration was performed using a filter paper with a pore size of 1 μm to remove undispersed carbon nanotubes, and the filtrate was used as a CNT dispersion.

  In the evaluation of Tables 5 to 9, the dispersant and carbon nanotubes or fullerenes are used at the concentrations shown in Tables 5 to 9, and after adding the nanocarbon substance to the dispersant aqueous solution, a thin film swirl type high speed mixer (manufactured by PRIMIX, film mix) Disperse at 40 m / s, 60 seconds or 60 seconds x 5 times using 40-L type), and then centrifuge using an ultracentrifuge (manufactured by KUBOTA, 7780 II) to obtain a supernatant. As an aqueous dispersion of nanocarbon material. The carbon nanotube aqueous dispersion was centrifuged at 10,000 rpm for 10 minutes, and the fullerene aqueous dispersion was centrifuged at 5000 rpm for 5 minutes. In addition, when evaluation is performed 1, 3, 7 days after dispersion, centrifugation is performed again in the same manner, and the supernatant is used as an aqueous dispersion of nanocarbon material.

[Evaluation of aqueous dispersion of nanocarbon substance]
1. Evaluation of dispersibility 1 (UV-visible absorption spectrum measurement and optical microscope observation)
The dispersibility of the nanocarbon material dispersion was evaluated by UV-visible absorption spectrum measurement and observation with an optical microscope. In Tables 1 and 2, evaluation is made for the case where Dispersant 1, Dispersant 9, and Dispersant 10 are used, and UV-visible absorption spectrum measurement is performed immediately after and one day after dispersion using V-550 manufactured by JASCO. Absorbance at 300 nm, 424 nm and 500 nm of the CNT dispersion liquid of Optical microscope observation was performed using AxioCam MRC (bright field, magnification: 1600 ×) manufactured by ZEISS. In Table 4, when the dispersants 1 to 4, the dispersant 9 and the dispersant 10 were used as the dispersant, the absorbance at 424 nm and 500 nm of the CNT dispersion immediately after dispersion was measured. In Table 7, when dispersants 1, 6, 8, 10, 12 to 14 are used as the dispersant, the low wavelength side (λmax of 260 nm to 280 nm) and the high wavelength side (340 nm to 360 nm) of the fullerene dispersion immediately after dispersion Absorbance at 660 nm was measured. In Table 8, when the dispersants 1, 3, 10, 12 to 14 were used as the dispersant, the absorbance at the low wavelength side, the high wavelength side, and 660 nm of the fullerene dispersion immediately after dispersion was measured. The higher the absorbance value is, the higher the concentration of CNTs is dispersed, and the better the dispersibility. Further, the absorbance at 660 nm indicates the turbidity of the dispersion, and indicates that the dispersion is cloudy when the absorbance is high. Tables 7 and 8 show the average particle size of fullerene particles and the concentration of fullerene in the fullerene dispersion. The average particle diameter of the fullerene particle showed the average particle diameter calculated from the weight distribution measured by dynamic light scattering (DLS, zeta potential particle size measurement system, manufactured by Otsuka Electronics, ELS-Z2). After removing the solvent and dispersant by heating 20 μL of the nanocarbon material dispersion at 550 ° C for 30 minutes while flowing nitrogen gas, the concentration of the fullerene is the dispersion liquid by subtracting the dry mass of the container from the mass of the residue The concentration of nanocarbon in it was calculated.

  The results of the ultraviolet-visible absorption spectrum measurement are shown in Table 1, Table 2, Table 4, Table 5, Table 7 and Table 8, and the results of the optical microscope observation are shown in FIGS.

  From Table 1, when dispersed under low output conditions, Dispersant 1 had a dispersing power equal to or greater than Dispersant 9 and Dispersant 10. In particular, when SW-CNT having extremely high cohesion among carbon nanotubes is dispersed, Dispersant 1 has very excellent dispersing power as compared to Dispersant 9 and Dispersant 10, and further dispersion 1 The short-term dispersion stability after the day was superior to Dispersant 9, and had the same dispersion stability as Dispersant 10.

  From Table 2, when dispersed under high power conditions, it was found that Dispersant 1 had good dispersibility.

  From Table 4, it was found that the dispersants 2 to 4 also had good dispersibility.

  From Table 5, it was found that the dispersibility of Dispersants 1, 3 and 5 to 8 was good also when dispersion was carried out using a thin film swirl type high speed mixer.

  From Table 7, it was found that the dispersants 1, 6, 8 also had good dispersibility for the dispersion of the fullerene.

  According to Table 8, when the concentration of the dispersant and the fullerene is 1.0% by mass and the number of times of stirring is increased to 5 times, the absorbances on the low wavelength side and the high wavelength side increase as a whole, but show turbidity. The absorbance at 660 nm was 0.33 for Dispersant 1, but 1.5 or more for the comparative substance, and the polymer dispersant of Dispersant 10 (CMC) and Dispersant 14 (PVP) was It was found that the value of dispersant 1 was extremely high, as high as 3 to 4 and significantly lower than that of the comparative example. When the appearances of the dispersions are compared, it is possible to obtain a highly transparent dispersion when using Dispersant 1, but a very turbid dispersion is obtained in the comparative example (FIGS. 8 to 13). ). In addition, when the absorbance at 660 nm after one week of dispersion is compared, only 0.1 decreases in Dispersant 1, and there is almost no change, but dispersion decreases in Dispersants 12 to 14; The high fullerene dispersion stability of Agent 1 was demonstrated.

  When the fullerene concentration in the dispersion immediately after dispersion was compared, it was found that Dispersant 1 was dispersed at 2.55 μg / μL and Dispersant 10 and 14 at a higher concentration. Although the concentrations of dispersants 12 and 13 were calculated to be high, it was observed from the optical micrograph that a large amount of aggregates were present. Therefore, it is considered that the concentration apparently increased because the concentration is uneven, but it is considered that the same is true for the one where the concentration after 7 days is increased.

  From these facts, it was shown that using Dispersant 1 it is possible to disperse the fullerene finely and uniformly even at high concentration.

  From FIGS. 1-13, it was confirmed that aggregation was hardly observed as compared with the dispersant listed in the comparative example, and Dispersant 1 was well dispersed. In particular, under the high-power conditions shown in FIG. 7 and under the condition where the CNT concentration is high, it was observed that Dispersant 1 was well dispersed, but Dispersant 10 was clearly aggregated. The dispersing agent 1 is well dispersed even under the condition that the fullerene is dispersed using the thin film swirl type high speed mixer shown in FIGS. 8 to 13, but the dispersing agent mentioned in the comparative example clearly aggregates. Was observed.

2. Evaluation of dispersibility 2 (scanning electron microscope (SEM))
A CNT dispersion having 0.1% by mass of dispersant and 0.1% by mass of MW-CNT was prepared. Dispersion with the ultrasonic homogenizer was performed under two conditions of low power (10 W, 10 minutes) and high power (30 W, 10 minutes).

  A dried sample of this CNT dispersion was prepared, and using a scanning electron microscope (SEM) (S-3400N, manufactured by Hitachi, Ltd.), observation of the dispersion state, such as damage and defects of carbon nanotubes and network formation, was performed.

  From the scanning electron microscope (SEM) photograph, the dispersibility of carbon nanotubes was visually evaluated on the basis of the following criteria.

Evaluation criteria ◎: One carbon nanotube confirmed, not aggregated and not cut at all ○: One carbon nanotube confirmed, not aggregated, but partially cut △: Partially carbon nanotubes can be confirmed, but aggregated or cut off ×: Carbon nanotubes can not be identified because they are aggregated

  The photographs are shown in FIG. 14 and FIG. 15, and the evaluation results of dispersibility are shown in Tables 1 and 2.

  The states of the carbon nanotubes were compared by scanning electron microscope (SEM) photographs on the right side (20,000 to 45,000 times) of FIGS. 14 and 15.

  From the results of low output (10 W) in FIG. 14, for Dispersant 1, it is possible to confirm that each of the carbon nanotubes is threadlike in a 30,000-fold photograph. From this photograph, it can be seen that the dispersed state is good, a carbon nanotube network is formed and no breakage occurs. In the dispersant 9, although one carbon nanotube can be partially confirmed, there are also parts that are not clearly seen. This is considered to be due to insufficient dispersion and partial aggregation. In the dispersing agent 10, one carbon nanotube can not be confirmed, and the carbon nanotube is aggregated to be insufficiently dispersed, and a carbon nanotube network is not formed. It was observed that the state of carbon nanotubes in the CNT dispersion dispersed under low output conditions was most uniformly dispersed when using Dispersant 1, and that the defect rate was also low, forming a network .

  In the high-power (30 W) results of FIG. 15, Dispersant 1 can not confirm the shape of carbon nanotubes one by one in a thread-like manner in a 45,000-times photograph, but the shape of carbon nanotubes can be confirmed, forming a network to some extent I understand that It is considered that this is because some carbon nanotubes are cut. On the other hand, in the dispersant 9, it is considered that carbon nanotubes can not be confirmed one by one, and it is considered that the carbon nanotubes are cut, and network formation is insufficient.

  On the other hand, it can be seen that the dispersing agent 10 has many large carbon nanotube lumps even at low magnification (760 times) and is aggregated. Since the dispersing agent 10 has low wettability in the dispersing step, it has been confirmed that a large number of carbon nanotubes adhere to the wall surface and the crushing horn, and therefore the dispersing agent 10 can not be dispersed uniformly, and carbon nanotube lumps are generated. It is considered that the formation could not be made.

3. Evaluation of handling property The following evaluation was performed on the handling property of the carbon nanotube dispersion liquid and the fullerene dispersion liquid.
(1) Solubility of the Dispersant in Water The solubility of the dispersant when dissolved in water at the concentrations shown in Table 3, Table 4 and Table 6 was evaluated based on the following criteria.

Evaluation criteria ◎: Immediate dissolution under 25 ° C. ○: Dissolution under a few minutes at 25 ° C. or dissolution immediately under 40 ° C. Δ: Dissolution under a few minutes under 40 ° C. ×: Dissolution

(2) Wettability of the Dispersant Aqueous Solution to Carbon Nanotubes and Fullerene Wettability of the aqueous dispersant solution to carbon nanotubes and fullerene was evaluated by a penetration test. In the penetration test, carbon nanotubes (MW-CNT) or fullerenes added at concentrations shown in Table 3, Table 4, Table 6 and Table 9 to dispersant aqueous solutions of the concentrations shown in Table 3, Table 4, Table 6 and Table 9 The time to sink was measured as the time required to penetrate.

  Also, based on the time required for penetration, the wettability was evaluated according to the following criteria.

Evaluation criteria ◎: The time required for permeation is less than 25 seconds ○: The time required for permeation is 25 seconds or more and less than 45 seconds Δ: The time required for permeation is 45 seconds or more and less than 600 seconds ×: The time required for permeation 600 More than a second

(3) Bonding amount of carbon nanotubes and fullerene to the wall surface and dispersing device (crushing horn or stirring blade) in the dispersing step Table 3, Table 4, Table 6 and Table 9 in aqueous dispersant solution Table 3, Table 4. After carbon nanotubes or fullerenes are added at the concentrations shown in Table 6 and Table 9, the amount of carbon nanotubes or fullerenes attached to the wall or dispersing device (crushed horn or stirring blades) in the dispersing step is "nearly not" It evaluated by visual observation in three steps of "small amount" and "many".

(4) Viscosity A carbon nanotube (MW-CNT) or fullerene dispersion was prepared at the concentrations shown in Tables 3, 4, 6, and 9, and the viscosity (mPa · s) at 25 ° C. of the dispersion was measured. . The measurement conditions of the viscosity are as follows.

Viscometer used: BROOKFIELD, DV-II + Pro
Rotor No. SC 4-18
Rotor speed: 60 rpm
Moreover, based on the measured viscosity, the following references | standards evaluated.

Evaluation criteria ◎: viscosity less than 3 mPa · s ○: viscosity 3 mPa · s or more and less than 10 mPa · s Δ: viscosity 10 mPa · s or more but less than 60 mPa · s ×: viscosity more than 60 mPa · s

(5) Comprehensive evaluation Comprehensive evaluation was performed on the handling according to the following criteria.

Evaluation criteria ◎: The handling property is very good overall from the above (1) to (4) O: the handling property is overall good from the above (1) to (4) Δ: the whole from the above (1) to (4) The handling property is low ×: the handling property is very low overall than the above (1) to (4)

  The above evaluation results are shown in Table 3, Table 4, Table 6 and Table 9.

  From Tables 3 and 4, Dispersant 1 has a very high solubility in water, and the wettability of the aqueous dispersant solution to carbon nanotubes is also very high as compared to Dispersant 9 and Dispersant 10, during the dispersing step. The adhesion of carbon nanotubes to the wall of the container was small, and the adhesion to the wall could be suppressed. In addition, the viscosity of the CNT dispersion using Dispersant 1 was low, and the handling properties of Dispersant 1 were very good overall.

  The handling properties of dispersants 2 to 4 as well as dispersant 1 were all very good.

  According to Table 6, the dispersants 1 to 8 have very high solubility in water, and the wettability of the aqueous dispersant solution to carbon nanotubes is also very high compared to the dispersants 9 to 12, and the container wall surface in the dispersing step is The adhesion of carbon nanotubes was small, and the adhesion to the wall could be suppressed.

  From Table 9, the wettability of the dispersants 1, 6 and 8 to the fullerene in the dispersant aqueous solution is also very high as compared with the dispersants 10, 13 and 14, and adhesion of the fullerene to the wall of the container during the dispersing step is small. It was possible to suppress adhesion to the wall surface.

4. Wettability of Carbon Nanotube Aqueous Dispersion to Base Material Using a PET film as the base material, the CNT dispersion liquid is dropped on the base material surface and a contact angle meter (DSA10-Mk2 manufactured by KRUSS) is used to obtain a contact angle (°) Was measured.

  Also, the wettability was evaluated based on the contact angle according to the following criteria.

Evaluation criteria ◎: contact angle less than 45 ° ○: contact angle 45 ° or more and less than 60 ° Δ: contact angle 60 ° or more and less than 65 ° x: contact angle 60 ° or more The evaluation results are shown in Tables 3 and 6.

  From Table 3 and Table 6, the wettability of the CNT dispersion to the base material is the highest when the dispersants 1, 3, 5 and 7 are used compared to when the dispersants 9 to 12 are used, in other words, For example, coating unevenness to the substrate is less than that of the dispersants 9 to 12, and uniform coating becomes possible.

  Thus, the dispersant represented by formula (I) can effectively disperse the nanocarbon material.

  That is, by using the dispersing agent represented by the formula (I), it is possible to disperse a nanocarbon substance with low energy and high concentration, as well as an aqueous dispersion of the nanocarbon substance which forms an excellent network with less damage and defects. You can get it.

5. Ultraviolet-Absorbing Performance of Fullerene Dispersion The ultraviolet-absorbing ability was evaluated from the absorbance at three wavelength bands of the fullerene dispersion shown in Tables 7 and 8. In Table 7, when using a dispersant and a fullerene concentration of 0.1% by mass, the dispersion using the example compound has high absorbance at the low wavelength side and the high wavelength side, and can disperse the fullerene at a high concentration. Was confirmed. In Table 8, when the dispersant and fullerene concentration were used at 1.0% by mass, the fullerene concentration of the dispersion increased, and the absorbances on the low wavelength side and the high wavelength side showed high values, but the dispersant of the present invention In this case, the absorbance at 660 nm showed a low value, and it was confirmed that ultraviolet light was selectively absorbed. In particular, in Example 23 in which Dispersant 1 is used, the fullerene concentration of the dispersion is high, but the absorbance at 660 nm is low. This is because the dispersant of the present invention finely disperses the fullerene uniformly, and therefore, the fullerene dispersion using the dispersant 1 shown in FIG. 8 provides a dispersion with high transparency.

6. Antioxidant activity of fullerene dispersions by DPPH radical scavenging method
In 1500 μL of an ethanol solution (250 μM) of DPPH (1,1-diphenyl-2-picrylhydrazyl) radical reagent, 1500 μL of a fullerene dispersion liquid in which 1.0 mass% of Dispersant 1, 10 to 14 and fullerene are dispersed Added. After 24 hours, after removing the fullerene by centrifugation (13,500 rpm, 15 minutes), the absorbance at 515 nm was measured by an ultraviolet-visible spectrophotometer (V-550, manufactured by JASCO Corporation) to determine the antioxidant activity.

  The antioxidant activity was evaluated based on the absorbance of the same concentration of DPPH according to the following criteria.

Evaluation criteria ○: The decrease in absorbance is 0.2 or more. ×: The decrease in absorbance is less than 0.2. The evaluation results are shown in Table 10.

  From Table 10, it was observed that the absorbance of DPPH at 515 nm decreased by 0.2 or more from the measurement results of the ultraviolet-visible spectrophotometer from the measurement result by the ultraviolet-visible spectrophotometer, and it was confirmed that the fullerene dispersion of Dispersant 1 had an antioxidant effect . This is because, when Dispersant 1 is used, not only the fullerene is dispersed at a high concentration, but also the fullerene is dispersed uniformly and finely, and the surface area of the fullerene is increased, so that the antioxidant activity is more enhanced. It is considered to be higher.

Claims (5)

A substance having a nanosize shape consisting of one layer (graphene sheet) of a six-membered ring graphite structure formed by covalent bonding of carbon atoms, or a closed shell cavity consisting of five-membered and six-membered rings formed by covalent bonding of carbon atoms Dispersants for aqueous dispersions of nanocarbon materials, which are
The following formula (I):
(Wherein, R ¹ represents an alkyl group having 1 to 22 carbon atoms, R ² represents an alkylene group having 1 to 22 carbon atoms, and R ³ represents an alkyl group having 1 to 22 carbon atoms, provided that R ¹ and R ² represent The carbon number of the R ¹ -CH-CH-R ² -moiety is selected to be 9 to 25. X and Y are both (1) X and Y are —O—SO ₃ M ¹ (M ¹ represents a counter cation of the hydrogen ions or salts.), (2) one of X and Y is -O- _{(AO) p} H a and the other is -O- _(AO) q H (AO carbon P represents an integer of 0 to 100, q represents an integer of 0 to 100, and the sum of p and q is 1 to 200). (3) Both X and Y are —OC (= O) —CH ₂ CH ₂ C (= O) OM ² (M ² is a hydrogen ion or a salt That represents a counter cation.), (4) one of X and Y is -OPO ^{₃ M} ₃ (M ₃ represents a counter cation comprising hydrogen ions or salts.) The other is a hydroxyl group, also (6 And any one of X and Y is —OC (= O) —CHR ⁷ —NR ⁸ R ⁹ · HX (R ⁷ is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkylthio alkyl group having 1 to 4 carbon atoms, thiol-containing alkyl group which has a thiol group attached to an alkyl group having 1 to 3 carbon atoms, a phenyl group, a hydroxyalkyl group, or a hydroxyphenyl group having a primary or secondary hydroxyl group with 1-3 carbon atoms .R ⁸ And R ⁹ each independently represents a hydrogen atom, a methyl group or an ethyl group, X represents a counter anion to be a salt), Z represents —O—C (= O) —, —C (= O) ) -O-, -NH-C (= O)-, or -O- Shown.) Represented by, dispersing agents for aqueous dispersion of the nano-carbon material. The dispersant according to claim 1, wherein the nanocarbon material is a carbon nanotube. The dispersant according to claim 1, wherein the nanocarbon material is a fullerene. A substance having a nanosize shape consisting of one layer (graphene sheet) of a six-membered ring graphite structure formed by covalent bonding of carbon atoms, or a closed shell cavity consisting of five-membered and six-membered rings formed by covalent bonding of carbon atoms An aqueous dispersion of a nanocarbon material, which is a substance of
The aqueous dispersion of nano-carbon material containing a dispersing agent and the nano-carbon material according to any one of claims 1 to 3. A substance having a nanosize shape consisting of one layer (graphene sheet) of a six-membered ring graphite structure formed by covalent bonding of carbon atoms, or a closed shell cavity consisting of five-membered and six-membered rings formed by covalent bonding of carbon atoms A method of producing an aqueous dispersion of a nanocarbon material, which is a substance of
In an aqueous solvent, the production method of the aqueous dispersion of the nano-carbon materials to be mixed and dispersed dispersing agent and the nano-carbon material according to any one of claims 1 to 3.