JP2007297255A - Dispersion containing carbon nanotubes - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dispersion of carbon nanotubes, which is excellent in dispersibility and dispersion stability and drastically improved in the electrical conductivity or transparency of a coated film, formed by applying the dispersion; and to provide a structure having a favorable electrical conductivity. <P>SOLUTION: The dispersion contains at least carbon nanotubes exhibiting basicity (A), a dispersing agent (B), and an organic solvent (C). A coating liquid is obtained by using the dispersion and the structure is obtained by applying the coating liquid on its surface. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a dispersion containing carbon nanotubes, and more particularly, to a dispersion of carbon nanotubes in which the conductivity of a coating film coated with the dispersion is greatly improved by using specific carbon nanotubes. .

  Carbon nanotubes have unprecedented properties such as high electrical conductivity, excellent mechanical properties, chemical stability, etc., for practical application of composite materials, semiconductor elements, conductive materials, hydrogen storage materials, etc. Research is underway.

However, in order to make the best use of the characteristics of carbon nanotubes, it is necessary to loosen very entangled aggregates, and it is generally known that dispersion is difficult. To date, there are documents that attempt to disperse or make ink by various methods (for example, Patent Document 1 and Patent Document 2). However, in many literatures, investigation of a dispersing agent for dispersing carbon nanotubes and easy modification / inking by chemically modifying the carbon nanotubes themselves are considered, but still sufficient dispersibility and dispersion stability. However, electrical characteristics, transparency, etc. were not obtained.
JP 2003-238126 A JP 2004-276232 A

  The present invention has been made in view of the above-described background art, and the problem is that the dispersibility and dispersion stability are good, and the conductivity and transparency of the coating film to which the dispersion is applied are greatly improved. The object is to provide a dispersion of carbon nanotubes.

  As a result of intensive studies to solve the above problems, the present inventor has found that the conductivity of the coating film coated with the dispersion is greatly improved by using specific carbon nanotubes. The present invention has been completed.

  That is, the present invention provides a dispersion characterized by containing at least a basic carbon nanotube (A), a dispersant (B) and an organic solvent (C).

  Moreover, this invention provides the coating liquid using said dispersion liquid. Moreover, this invention provides the structure formed by apply | coating said coating liquid.

  According to the present invention, it is possible to provide a dispersion of carbon nanotubes that has good dispersibility and dispersion stability, and has greatly improved conductivity and transparency of a coating film to which the dispersion is applied.

  Hereinafter, the present invention will be described. However, the present invention is not limited to the following embodiments, and can be arbitrarily modified and implemented.

<Carbon nanotube (A)>
The kind of the carbon nanotube (A) used in the dispersion of the present invention is not particularly limited, and any single-walled, double-walled or multi-walled carbon nanotube can be used depending on the application. Multi-walled carbon nanotubes are preferred from the viewpoint of being easily dispersible because they are not easily crushed or crushed. The diameter and length of the carbon nanotube are not particularly limited and can be applied to any size, but the diameter is preferably 0.5 nm to 1000 nm, particularly preferably 3.5 nm to 400 nm, and 5 nm to 200 nm. Further preferred. The length is preferably 0.1 μm to 50 μm, particularly preferably 0.2 μm to 40 μm, and further preferably 0.5 μm to 30 μm.

  In the present invention, it is essential that the carbon nanotube (A) is basic, that is, the pH is 7 or more. When the carbon nanotube (A) has a pH of 7 or more, the conductivity of the coating film obtained by coating the carbon nanotube (A) is good. The pH is preferably in the range of 7 to 12, particularly preferably the pH is in the range of 8 to 12, and more preferably the pH is in the range of 9 to 11.

  Here, in the present invention, “pH of carbon nanotube (A)” is defined as a value measured by the method described in Examples.

  The method for producing the basic carbon nanotube (A) is not particularly limited, but it is also preferable that the acidic treatment is not performed for catalyst removal or the like. Moreover, even if an acid treatment is performed, it is preferable that the surface be treated to be basic.

  Further, among the surface functional groups of the carbon nanotube (A), an acidic functional group such as a carboxyl group is formed with an aqueous solution of an alkali metal salt such as sodium hydroxide, potassium hydroxide, sodium carbonate or sodium bicarbonate, aqueous ammonia or the like. A surface-treated product is also preferable. For example, it is also preferable to perform a proton exchange reaction by dispersing carbon nanotubes in an aqueous sodium hydroxide solution.

<Dispersant (B)>
The dispersant (B) used in the present invention is not particularly limited as long as it is a dispersant generally used for preparing a dispersion. For example, a polymer dispersant, a surfactant, a coupling agent, or the like is used. can do.

As the dispersant (B) of the present invention, the following polymer dispersants (1), (2) and (3) can be mentioned as preferable examples.
(1) A comb-shaped polymer having a carbon nanotube affinity group and a solvent affinity group in the main chain or side chain.
(2) A polymer having a plurality of carbon nanotube affinity groups in the main chain.
(3) A linear polymer having a carbon nanotube affinity portion at one end of the main chain.

  Hereinafter, preferred polymer dispersants as the dispersant (B) used in the present invention will be described in accordance with the above classifications (1), (2), and (3). The polymer dispersant (1) is one in which the side chain is bonded to the main chain like a comb tooth. The “carbon nanotube affinity group” in the polymer having a comb structure refers to a functional group having a strong adsorptive power to the surface of the carbon nanotube.

  A plurality of the above-mentioned carbon nanotube affinity groups may be present not only at the end of the side chain but also in the middle of the side chain or in the main chain. Examples of such a carbon nanotube affinity group include a tertiary amino group, a quaternary ammonium, a heterocyclic group having a basic nitrogen atom, a hydroxyl group, a carboxyl group, a phenyl group, a lauryl group, a stearyl group, and dodecyl. Group, oleyl group and the like. One or more carbon nanotube affinity groups exist and function as an anchor for the carbon nanotube surface.

  Examples of the solvent affinity group in the polymer dispersant (1) include a lipophilic polymer chain.

  The polymer dispersant (1) is not specifically limited, but is disclosed in, for example, JP-A-5-177123, JP-A-54-037082 and JP-B-7-024746. You can list what you have.

  In the polymer dispersant (1), those having 2 to 3000 carbon nanotube affinity groups per molecule are preferred. If 2 to 3000 carbon nanotube-affinity groups are contained in one molecule, at least stable dispersibility can be maintained, and there is no influence of deterioration of dispersibility caused by an increase in viscosity. More preferably, it is 25 to 1500.

  In the polymer dispersant (1), those having 2 to 1000 side chains having a solvent affinity group per molecule are preferable. If 2 to 1000 side chains are contained in one molecule, stable dispersibility can be obtained by solvation, and there is no influence of dispersibility due to an increase in viscosity. More preferably, it is 5 to 500.

  The polymer dispersant (2) is a polymer having a structure in which a plurality of carbon nanotube affinity groups are arranged along the main chain. The polymer dispersant (2) is not specifically limited. For example, JP-A-4-210220, JP-A-60-016631, JP-A-2-000612, Examples thereof disclosed in JP-A 63-241018, JP-A-1-279919, JP-A-6-1000064, and the like.

  The polymer dispersant (2) is preferably one having 2 to 3000 carbon nanotube affinity groups in one molecule. If it is 2 to 3000, at least stable dispersibility can be maintained, and there is no influence of deterioration of dispersibility caused by an increase in viscosity. More preferably, it is 25-1500.

  The polymer dispersant (3) is not specifically limited, but for example, JP-A-46-7294, U.S. Pat. No. 4,656,226, U.S. Pat. No. 4,032,698, U.S. Pat. No. 4,070,388. And an AB block type polymer disclosed in JP-A-1-204914.

  The polymer dispersant (3) is preferably one having 2 to 3000 carbon nanotube affinity groups in one molecule. Within this range, at least stable dispersibility can be maintained, and there is no influence of deterioration of dispersibility caused by an increase in viscosity. More preferably, it is 5 to 1500.

  The amine value of the dispersant (B) of the present invention including the polymer dispersant (1), (2), (3) and the like is not particularly limited, but is in the range of 5 to 100 mgKOH / g. Preferably there is. When the amine value is less than 5 mgKOH / g, the adsorptive power on the surface of the carbon nanotube (A) is insufficient, so that the dispersant (B) is easily detached from the surface of the carbon nanotube (A), and the dispersion stability is lowered. May occur. On the other hand, when the amine value of the dispersant exceeds 100 mgKOH / g, the ratio of the steric repulsion layer to the adsorbed component of the dispersant adsorbed on the surface of the carbon nanotube (A) becomes too small, and sufficient dispersion stability cannot be obtained. There is a case. A dispersant having an amine value of 6 to 80 mgKOH / g is particularly preferable, and a dispersant having an amine value of 7 to 70 mgKOH / g is more preferable.

  The number average molecular weight of the dispersant (B) of the present invention is not particularly limited, but a polymer dispersant having a number average molecular weight of 300 or more is preferable, and the number average molecular weight is more preferably in the range of 1,000 to 100,000. Within this range, the dispersibility is stable and the viscosity does not become too high, so that good dispersibility can be obtained. That is, when the number average molecular weight is less than 1000, the dispersant adsorbed on the surface of the carbon nanotube (A) does not sufficiently function as a three-dimensional repulsion layer, and the carbon nanotube (A) may reaggregate. Further, when the number average molecular weight exceeds 100,000, it may be difficult to produce a dispersion with good reproducibility, or conversely, it may act as a flocculant. The number average molecular weight of a particularly preferable dispersant is in the range of 1000 to 10,000, and more preferably in the range of 1000 to 5000.

  The dispersant (B) of the present invention is particularly preferably the above-described polymer dispersant (1), (2) or (3) and having an amine value in the above range for the reasons described above.

  Specific examples of preferable dispersant (B) in the present invention include, for example, Solsperse 20000, 24000, 26000, 27000, 28000 manufactured by Zeneca; Disperbic 160, 161, 162, 163, 164, 165, 166 manufactured by BYK Chemie. 170, 180, 182, 2000, 2001, etc .; EFKA-46, 47, 49 manufactured by EFKA Chemical Co., Ltd. Polymers 100, 120, 150, 401, 402, 403, 450, 451, 452, 453; manufactured by Ajinomoto Fine Techno Co., Ltd. Azisper PB711, PA111, PB811, PB821, PB822, PW911; Kyoeisha Chemical Co., Ltd. florene DOPA-158, DOPA-22, DOPA-17, TG-730W, G-700, TG-720W etc. can be mentioned.

<Organic solvent (C)>
The organic solvent (C) contained in the dispersion of the present invention is not particularly limited as long as it can dissolve and / or disperse at least the basic carbon nanotubes (A) and the dispersant (B). However, a solvent that is not compatible with water at an arbitrary ratio at 20 ° C. is preferable for maintaining dispersibility and dispersion stability.

  As the organic solvent (C), the organic solvent is compatible with only 40% by mass or less at 20 ° C. with respect to the total mass of the organic solvent and water, and the total mass of the hydrophobic organic solvent and water. On the other hand, the water is preferably compatible with 20% by mass or less at 20 ° C. Further, the solvent is compatible with 30% by mass or less at 20 ° C. with respect to the total mass of the organic solvent and water, and 10% at 20 ° C. with respect to the total mass of the organic solvent and water. Those that are compatible with not more than mass% are particularly preferred. When a solvent having too high compatibility with water is used, the dispersion stability of the carbon nanotube (A) in the present invention may not be obtained, or the dispersant (B) may not be compatible with the solvent.

  Specific examples of the organic solvent (C) include aromatic hydrocarbons such as toluene, xylene, and ethylbenzene; ketones such as methyl ethyl ketone, cyclohexanone, and methyl isobutyl ketone; propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether Monoalkyl ether acetates of alkylene glycols such as acetate, propylene glycol monopropyl ether acetate, dipropylene glycol monomethyl ether acetate, dipropylene glycol monoethyl ether acetate, dipropylene glycol monopropyl ether acetate; propylene glycol diacetate, dipropylene Diacetates of alkylene glycols such as glycol diacetate; γ-butyrolas Tons, γ-valerolactone, γ-caprolactone, δ-valerolactone, δ-caprolactone, and other lactones; diethyl ether and other ethers; methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, and other carboxylic acid alkyl esters And the like are preferable. These are used alone or in a mixture of two or more.

  Particularly preferred are ketones, esters, ethers or aromatic hydrocarbons from the viewpoint of excellent dispersion stability of the carbon nanotubes (A), the compatibility of the dispersant (B), and the like. More preferred are ketones or esters.

<Resin (D)>
If necessary, the dispersion of the present invention can further contain the resin (D). The resin (D) dissolved and contained in the dispersion of the present invention is not particularly limited, and examples thereof include various thermoplastic resins, thermosetting resins, photocurable resins, and biodegradable resins.

  Thermoplastic resins include polyamide resins, polyimide resins, polyester resins, polyacetal resins, polycarbonate resins, polyolefin resins, poly (meth) acrylic resins, polyphenylene oxide resins, polystyrene resins, polyvinyl chloride. Based resins and the like. Examples of thermosetting resins include urea resins, melamine resins, urethane resins, phenol resins, epoxy resins, silicon resins, unsaturated polyester resins, and the like. Examples include lactic acid resins. Other examples include ionomer resins, rosin-modified maleic acid resins, and alkylene- (meth) acrylate resins, and may be a mixture thereof.

  Particularly preferred resins (D) used in the present invention include urethane resins or poly (meth) acrylic resins from the viewpoints of dispersibility, dispersion stability, conductivity of the coating film, transparency, and the like.

<Content ratio>
The content ratio of each component in the dispersion liquid of the present invention is such that the dispersibility and dispersion stability of the basic carbon nanotube (A) are good, and the dispersibility of the dispersion liquid and the conductivity of the coating film are good. Although there is no particular limitation, preferred ranges include the following ranges. "%" Is mass% with respect to the whole dispersion.
Carbon nanotube (A) 0.01-20%
Dispersant (B) 0.1-40%
Organic solvent (C) 20-99%
Resin (D) 0-30%

Moreover, as a particularly preferable range,
Carbon nanotube (A) 0.1-10%
Dispersant (B) 0.5-20%
Organic solvent (C) 50-98%
Resin (D) 0-20%

Further, as a more preferable range,
Carbon nanotube (A) 0.2-8%
Dispersant (B) 1-10%
Organic solvent (C) 75-97%
Resin (D) 0-10%

  If the content of the basic carbon nanotube (A) is too large, it may be difficult to disperse. On the other hand, although it is dispersed even at a lower concentration than this, such a dispersion may have a low utility value, and the conductivity of the coating film may not be sufficiently high.

  If the content of the dispersing agent (B) is too large, the viscosity of the dispersion increases, and it may be difficult to disperse the carbon nanotube (A). If too small, the dispersing agent acts on the carbon nanotube (A). In some cases, the amount is insufficient to disperse well.

  If the content of the resin (D) is too large, the viscosity of the dispersion increases, and it may become difficult to disperse the carbon nanotubes (A) or the applicability may deteriorate.

  Further, in the dispersion of the present invention, if necessary, an antioxidant, a light stabilizer, an ultraviolet absorber, a lubricant, a pigment, a flame retardant, a filler and the like can be contained. In that case, it contains in the range which does not impair the said effect of the dispersion liquid of this invention.

<Distribution method>
There is no particular limitation on the dispersion method, and a known method is used. Specific examples include a media dispersion method such as a bead mill dispersion method; a medialess dispersion method such as an ultrasonic dispersion method and a roll mill dispersion method. Among these, from the viewpoint of dispersion stability and the like, the ultrasonic dispersion method or the bead mill dispersion method is preferable, and the bead mill dispersion method is particularly preferable.

  The dispersion liquid of the present invention is preferably used as a coating liquid. Since the coating film or structure obtained by applying and drying the dispersion of the present invention has excellent conductivity and transparency, it is suitably used for applications where such performance needs to be improved. Particularly preferably, it is used for antistatic applications. The coating liquid contains ink. A particularly preferred embodiment is to use a known component of the ink in the dispersion of the present invention and use it as a conductive ink.

  The structure formed by applying the dispersion liquid of the present invention as a coating liquid is required to have conductivity, antistatic properties, etc. for trays, protective films, housings, cover tapes, food packaging materials, optical members, display members, etc. Things.

  Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. However, the present invention is not limited to these examples as long as the gist thereof is not exceeded. Unless otherwise specified, including the values in the table, “%” indicates “mass%” and “parts” indicates “parts by weight”.

  Each physical property value in the examples was measured as follows. In the present invention, such physical property values are defined as values measured as follows.

<PH of carbon nanotube>
・ Measuring equipment: Lacom tester meter EUTECH Instruments, OAKTON Instruments (USA standard compliant)
・ Measuring method: After calibrating the equipment with a standard solution corresponding to the USA standard (pH = 4.0, 6.8, 10.0, slightly different depending on room temperature), 0.1 g of carbon nanotubes in 20 g of ion-exchange water at 20 ° C. Was added to the suspension, and the tester electrode was placed in the suspension at 20 ° C. for 5 minutes. The pH of this suspension is defined as “pH of carbon nanotube”.

<Amine value of dispersant (mgKOH / g)>
A few grams of the measurement sample was precisely weighed and dissolved in glacial acetic acid. A commercially available perchloric acid (HClO ₄ ) 0.1N acetic acid solution for inspection was dropped therein with a burette and titrated. MgKOH / g was calculated from the dripping amount at the time when the equivalent point was reached by potentiometric titration, and was defined as “amine value of dispersant (mgKOH / g)”. When the dispersant is already in the form of a commercially available product, etc., the solution is precisely weighed as a measurement sample and used for measurement, and the measured value is converted into the dispersant concentration and the dispersant alone (solid) Min, non-volatile content).

<Particle size distribution, 50% particle size (μm)>
・ Measuring device: Microtrac particle size distribution analyzer Nanotrac NPA150 (UPA150) manufactured by Nikkiso Co., Ltd. ・ Measuring principle: Laser scattering method (method of calculating from frequency spectrum measurement result obtained from Doppler shifted light scattered by particles)
・ Measurement method: Enter the required information (particles are not spheres, light absorption type, refractive index, viscosity / refractive index of solvent) into the device according to the measurement method explanation document of the device, set zero with the solvent used, The dispersion was diluted to a concentration capable of measuring the particle size distribution and measured.

<Surface resistance (Ω)>
・ Measurement device: Hirestar UP MCP-HT450 (Mitsubishi Chemical Corporation)
・ Measurement principle: MCC-B method ・ Measurement method: Applying and drying the dispersion liquid on the substrate to form a coating film, pressing the electrode (probe) against the sample surface according to the measurement method explanation document of the apparatus, at 20 ° C., The current value flowing on the surface was detected. The thin film sample formed on the insulating substrate was pressed against the electrode (probe) from above the sample.

<Transmittance (%)>
・ Measurement device: Haze meter HM-150 (Murakami Color Research Laboratory)
Measurement method: Measured according to the new standard for measuring total light transmittance (ISO 13468-1, JIS K7361). Calibration is performed in a state where there is nothing in the detection site (air) (automatic calibration), and then a sample obtained by applying and drying the dispersion on a transparent film for optical members having a sufficiently high transmittance is sandwiched between the substrate and the detection site. did.

<Haze>
・ Measurement device: Haze meter HM-150 (Murakami Color Research Laboratory)
Measurement method: Measured according to the new standard for haze measurement (ISO 14782, JIS K 7136). Calibration was performed in a state (air) in which there was nothing at the detection site (automatic calibration), and then the sample coated with the dispersion liquid on the transparent film for optical member and dried was sandwiched between the detection site and the substrate.

[Evaluation of dispersion containing no resin (D)]
<Preparation of carbon nanotube dispersion 1>
The carbon nanotube dispersion 1 (hereinafter abbreviated as “dispersion 1”) was prepared as follows. That is, after thoroughly stirring 25.0 parts of a solution in which azisper PB821 was dissolved in propylene glycol monomethyl ether acetate to obtain an active ingredient of 40% and 70.0 parts of methylisoptyl ketone (hereinafter abbreviated as “MIBK”), 5.0 parts of carbon nanotube CNT-1 was added, and dispersion was performed for 12 hours with a paint shaker using zirconia beads having an average diameter of 2 mm and 0.3 mm.

  The carbon nanotube CNT-1 is a multi-walled carbon nanotube having an average diameter of 10 to 15 nm and an average length of 10 to 30 μm, and is a carbon nanotube that has been subjected to basic treatment at the final stage of synthesis.

<Preparation of dispersions 2-6 and comparative dispersions 7-9>
Dispersions 2 to 6 and comparative dispersions 7 to 9 were obtained in the same manner as the dispersion 1, except that each component in the dispersion 1 was replaced with the components shown in Table 1.

The description in Table 1 will be described below.
-The numbers in Table 1 represent parts by weight.
"Ajisper PB821" is a trade name of a basic functional group-containing copolymer manufactured by Ajinomoto Fine Techno Co., Ltd. The amine value is 9 mgKOH / g, and the acid value is 17 mgKOH / g.
“Disperbyk-2000”, “Disperbyk-2001”, and “Disperbyk-161” are trade names of basic functional group-containing block copolymers manufactured by Big Chemie.
-The amine values of the dispersants are summarized as follows. Since the commercially available product may be a solution in parentheses, the nonvolatile content is shown. Moreover, the following amine value is not the amine value of a commercial solution, but an amine value in terms of non-volatile content (single dispersant).
Azisper PB821 (100%) 9mgKOH / g
Disperbyk-2000 (40%) 10 mg KOH / g
Disperbyk-2001 (46%) 63 mgKOH / g
Disperbyk-161 (30%) 37 mg KOH / g
-"Azisper PB821 40% solution" is a solution obtained by diluting Azisper PB821 (non-volatile content 100%) with propylene glycol monomethyl ether acetate to a concentration of 40%.
-"Disperbyk-2000 40% solution" is a commercial 40% solution diluted with propylene glycol monomethyl ether acetate and ethylene glycol monobutyl ether.
-"Disperbyk-2001 46% solution" is a 46% solution of a commercial product diluted with propylene glycol monomethyl ether acetate, ethylene glycol monobutyl ether and propylene glycol monomethyl ether as it is.
"Disperbyk-161 30% solution" is a 30% solution of a commercial product diluted with propylene glycol monomethyl ether acetate and butyl acetate as it is.
“MIBK” represents methyl isobutyl ketone, and “MEK” represents methyl ethyl ketone.
“CNT-1” is a carbon nanotube described in the text of the examples.
“A-MWNTs-1020” and “S-MWNTs-10” are trade names of carbon nanotubes manufactured by Shenzhen Nanotechport.
“VGCF-H” is a trade name of carbon nanotubes manufactured by Showa Denko KK

<Evaluation of Dispersions 1-6 and Comparative Dispersions 7-9>
Dispersions 1-6 and Comparative Dispersions 7-9 were each mixed with 0.6 g and MIBK 9.4 g were mixed to obtain a 0.3% carbon nanotube solution. This solution was applied onto Tetron film HS-74 (manufactured by Teijin DuPont, easy-adhesion PET film) using a bar coater # 3, and dried in an oven at 120 ° C. for 2 minutes. The surface resistance of this coating film was measured by the above method. The results are shown in Table 2 together with “50% particle size”, “transmittance” and “haze” measured by the above method.

From the results of Table 2, all of the dispersions 1 to 6 (dispersions containing no resin) prepared using basic “CNT-1” (pH is 10.0) as the carbon nanotube (A) The surface resistance of the coating film formed using it was sufficiently small, on the order of 10 ⁹ (Ω) or less, and sufficient conductivity could be imparted to the coating film.

On the other hand, all of Comparative Dispersions 7 to 8 using carbon nanotubes having a pH of less than 7 have a large surface resistance of 10 ¹⁰ (Ω) or more, and are sufficient for the coating film. The conductivity could not be imparted.

[Evaluation of dispersion containing resin (D)]
<Preparation of dispersion 10>
Mixing and stirring 6.0 parts of carbon nanotube dispersion 1 and 7.4 parts of 15% MIBK solution of styrene acrylic resin (manufactured by Mitsubishi Rayon Co., Ltd., Dianar BR52) and 86.6 parts of MIBK as resin (D) By doing so, Dispersion 10 was prepared.

<Preparation of dispersions 11 and 12, comparative dispersions 13 to 15 and dispersions 16 to 19>
Except for using the dispersion liquid 1 or 2 shown in the second column of Table 3 and the comparative dispersion liquids 4 to 6, and using the resin solution shown in Table 3 instead of the resin solution blended with the dispersion liquid 10, Dispersions 11 and 12, comparative dispersions 13 to 15 and dispersions 16 to 19 were prepared in the same manner as dispersion 10.

-The numerical value of content in Table 3 represents a weight part.
・ "Dianar BR52" is a styrene acrylic resin (Mitsubishi Rayon Co., Ltd.)
・ "Dynal BR52 solution" is a 15% MIBK solution of Dynal BR52. "Paralloid B-44" is an MMA copolymer (Rohm & Haas)
“Paralloid B-44 solution” is a 20% MIBK solution of paraloid B-44. “UV resin” is a mixture of the following parts of (1), (2) and (3) below.
(1) Biscoat 230D (HDDA dimer, manufactured by Osaka Organic Chemical Co., Ltd.) 0.7 part (2) PET (a mixture of pentaerythritol triacrylate and pentaerythritol tetraacrylate, manufactured by Nippon Kayaku Co., Ltd.) 0.7 part (3) KTO45 (manufactured by Sartomer) 0.1 part (a) Mixture of 2-hydroxy-2-methyl-1- (1-methylvinyl) phenolpropane and 2-hydroxy-2-methyl-1-phenyl-1-propanone (B) Mixture of trimethylbenzophenone and methylbenzophenone (c) Mixture of phosphine oxide In the mixture (a) :( b) :( c) = 4: 4: 3 (mass ratio) , Styrene acrylonitrile copolymer (Daicel Polymer Co., Ltd.)
・ "Sebian NA solution" is a 20% MIBK solution of Sebian NA. "Epicoat 1004" is an epoxy resin (manufactured by Japan Epoxy Resin).
"Epicoat 1004 solution" is a 20% MIBK solution of Epicoat 1004

<Evaluation of dispersions 10-12, comparative dispersions 13-15, and dispersions 16-19>
The above dispersion or comparative dispersion was applied onto Tetron film HS-74 (manufactured by Teijin DuPont, easy-adhesion PET film) using bar coater # 3, and dried in an oven at 120 ° C. for 2 minutes. did. About this coating film, the surface resistance, the transmittance | permeability, and the haze were measured by the said method. The results are shown in Table 4.

From the results of Table 4, the dispersions 10 to 12 and the dispersions 16 to 19 containing the resin (D) using basic “CNT-1” (pH is 10.0) as the carbon nanotubes (A) are as follows. The surface resistance of the coating film prepared using it was as small as 10 ⁹ (Ω) or less, and sufficient conductivity could be imparted to the coating film.

On the other hand, carbon nanotubes having a pH of 7 or less (the comparative dispersion 13 using the comparative dispersion 7, the dispersion 14 using the comparative dispersion 8, and the dispersion 15 using the comparative dispersion 8 are used. The surface resistance of the coating film thus formed was as large as 10 ¹⁰ (Ω) or more, and sufficient electrical conductivity could not be imparted to the coating film.

The dispersion of carbon nanotubes of the present invention is excellent in dispersibility and dispersion stability, and the coating film coated with the carbon nanotube has low surface resistance and high transmittance, so that antistatic, surface conductivity imparting, transparency It is widely used for composite materials such as trays, conductive films, etc., etc., electronics, mechanics, chemical reaction materials, and the like.

Claims (6)

  A dispersion characterized by containing at least a basic carbon nanotube (A), a dispersant (B) and an organic solvent (C).   The dispersion liquid according to claim 1, wherein the pH of the carbon nanotube (A) exhibiting basicity is in the range of 7-12.   The dispersion according to claim 1 or 2, wherein the amine value of the dispersant (B) is in the range of 5 to 100 mgKOH / g.   The dispersion according to any one of claims 1 to 3, wherein the resin (D) is further dissolved.   A coating solution using the dispersion according to any one of claims 1 to 4. A structure formed by applying the coating liquid according to claim 5.