JP2008024568A - Dispersion liquid of carbon nanotube and coating film of carbon nanotube - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dispersion liquid which is prepared by using a carbon nanotube and is excellent in dispersion stability and to provide a coating film which is formed by using the dispersion liquid as a coating liquid and is excellent in haze and surface electrical resistance. <P>SOLUTION: The dispersion liquid is prepared by using the carbon nanotube having a specific outside diameter (10-50 nm) and specific crystallinity (0.70-1.50), a compound having a basic functional group, a compound of ≤15,000 molecular weight and a ketone-based solvent. The prepared dispersion liquid is applied to a base material to obtain the coating film of the carbon nanotube, which is excellent in haze and surface electrical resistance. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a dispersion and a coating film containing so-called carbon nanotubes, and more particularly to a carbon nanotube dispersion having excellent dispersion stability and a conductive carbon nanotube coating film obtained as a coating product thereof.

  A carbon nanotube is a kind of fullerene in which a carbon six-membered ring network (graphene sheet) is formed into a single-layer or multi-layer tube shape, a single-wall nanotube is a single-wall nanotube (SWNT), and a multi-wall is a multi-wall It is called a nanotube (MWNT).

  One of the features of this carbon nanotube is its low electrical resistance, and in terms of its application, fuel cell, negative electrode for Li-ion secondary battery, electron emission source for flat panel display, or transparent conductive material are examined. Has been. For example, Patent Document 1 proposes to obtain a conductive coating film with good transparency using carbon nanotubes having an outer diameter of less than 3.5 nm. In this case, it is preferable to use SWNT having a single crystal layer of carbon.

  By the way, since the carbon crystal forming the carbon nanotube has few functional groups on the surface like graphite, and the interaction with the dispersing agent is small, it is possible to obtain a carbon nanotube dispersion liquid having a uniform and good stability. difficult. Therefore, carbon nanotubes produced by CVD (chemical vapor deposition) are heat-treated at 400 to 600 ° C. or acid-treated with concentrated nitric acid, concentrated sulfuric acid, etc., and dispersed in a polymer solution containing amino groups ( Patent Document 2), disperse nanotubes with acidic functional groups on the surface by plasma treatment (Patent Document 3), or base carbon nanotubes modified with acidic functional groups using an acid having an oxidizing property such as concentrated nitric acid. It has been considered to obtain a highly stable dispersion using carbon nanotubes whose surface is chemically modified, such as dispersion in a polar solvent (Patent Document 4).

JP 2005-255985 A JP 2004-276232 A JP 2003-300716 A JP 2004-216516 A

  However, when carbon nanotubes whose surfaces are chemically modified by acid treatment or plasma treatment to obtain a stable dispersion are used, the surface of the carbon nanotubes is contaminated or defects are generated in the carbon nanotubes. However, it was difficult to obtain a carbon nanotube coating film having good conductivity and high transparency.

  The present invention provides a coating liquid (carbon nanotube dispersion liquid) having good dispersion stability in a system using untreated carbon nanotubes and an organic solvent, and a conductive coating film obtained by applying the coating liquid (carbon nanotube dispersion liquid) An object is to provide a carbon nanotube coating film).

  As a result of studying the dispersion characteristics of carbon nanotubes, the present inventors have found that the diameter, crystallinity, and type of the nanotubes are related to dispersion stability, and have completed the present invention.

  That is, the present invention relates to a carbon nanotube dispersion obtained by dispersing carbon nanotubes in a solvent, a carbon nanotube having a diameter of 10 to 50 nm, a compound containing a basic functional group, a compound having a molecular weight of 15000 or less, a ketone solvent, It is set as the structure containing this. The carbon nanotube in this case is preferably a carbon nanotube having a crystallinity of 0.70 to 1.50. The compound having a molecular weight of 15000 or less is preferably an acrylic compound containing at least one of an acrylic group and a methacryl group. The molecular weight here means the weight average molecular weight.

  The carbon nanotube coating film according to the present invention is obtained by applying the carbon nanotube dispersion liquid on a substrate (a member such as glass or plastic for which a coating film is to be formed) and has a diameter of 10 to 50 nm. In addition, it is a coating film containing carbon nanotubes having a crystallinity of 0.70 to 1.50.

  In the present invention, in particular, the carbon nanotube is a MWNT type in which a plurality of graphene sheets are stacked, a compound containing a basic functional group is used as a dispersant, and an acrylic monomer or oligomer having a molecular weight of 15000 or less is used as a binder. It is preferable to use a ketone organic solvent. Here, the ketone organic solvent means an organic solvent system containing 50 wt% or more of ketones such as methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), and cyclohexanone in the solvent composition alone or in combination. .

By applying the carbon nanotube dispersion of the present invention, a coating film having good transparency, that is, high total light transmittance, low haze value (hereinafter also referred to as “haze”), and low surface electrical resistance. Obtainable. Although the total light transmittance, haze, and surface electrical resistance depend on the carbon nanotube content and thickness of the coating film, the total light transmittance is 60% or more and the haze is 2% by adjusting the coating thickness. Hereinafter, a coating film having a surface electrical resistance of 10 ⁵ Ω / □ to 10 ¹¹ Ω / □ could be obtained.

In the carbon nanotube dispersion liquid of the present invention, a carbon nanotube having a diameter of 10 nm or more and 50 nm or less, crystallinity of 0.70 or more and 1.50 or less is used, a compound containing a basic functional group, an acrylic having an average molecular weight of 15000 or less. At least one of a system monomer or an oligomer is used. By coating this carbon nanotube dispersion on the substrate, a coating film having a surface electrical resistance of 10 ³ Ω / □ to 10 ¹¹ Ω / □ can be obtained. In this case, by further adjusting the thickness of the coating film and the content of the carbon nanotube, the total light transmittance at a wavelength of 380 nm to 780 nm is 60% or more, the haze is 2% or less, and the surface electrical resistance is 10 ⁵ Ω / □ to A coating film containing carbon nanotubes in the range of 10 ¹¹ Ω / □ can be obtained.

  Here, the measurement of the total light transmittance and haze can be evaluated by correcting the light source and the visibility by using a spectrophotometer. In the present invention, however, IL-N is applied to a JASCO V-570 spectrophotometer. The measurement was performed using a combination of a 472 type large integrating sphere device and a haze value calculation program. The measurement was performed under the conditions that the response was Quick, the bandwidth was 2.0 nm, the near infrared was 8.0 nm, and the scanning speed was 400 nm / min, and the calculation was performed under the conditions that the field of view was 2 degrees and the light source was D65. The surface electrical resistance was measured and evaluated using Loresta or Hiresta manufactured by Mitsubishi Yuka.

The diameter of the carbon nanotube was evaluated by observing the carbon nanotube or the coating film with an electron microscope (SEM). The crystallinity was evaluated using a Raman spectrum. In the present invention, the crystallinity is RAMASCOPE manufactured by RENISHAW, the excitation light source is an Ar ion laser (20 mW), the spot diameter is 20 μm, the objective lens is 50 times, the focus is 50%, ND100%, static mode (center 1500 cm ⁻¹ ), integration The Raman spectrum was measured under the condition of 10 seconds × 10 times (n = 4). Then, 1580 cm ⁻¹ peak (G) which is considered to be caused by graphite structure, 1350 cm ⁻¹ peak (D) which is considered to be caused by broken graphite, and 1620 cm ⁻¹ peak which is considered to be caused by C═C structure are curve-fitted. The area ratio (G / D) of G and D was evaluated as crystallinity.

  The carbon nanotube coating film according to the present invention can be obtained by applying the carbon nanotube dispersion liquid to a substrate such as glass or polyethylene terephthalate (PET). The carbon nanotube dispersion can be obtained by mixing and dispersing a carbon nanotube having a diameter of 10 nm or more and 50 nm or less and a compound containing a basic functional group in an organic solvent. Carbon nanotubes having a diameter of less than 10 nm have poor dispersibility, and those having a diameter of more than 50 nm have poor dispersion stability. In the case of SWNT, the diameter of the carbon nanotube forms a so-called bundle structure (bundle) and is observed to be thicker than the diameter of one nanotube. The diameter referred to in the present invention is not a bundle but an original diameter. Moreover, you may use the dispersing agent which consists of a high molecular compound etc. which contain a basic functional group of molecular weight 25000 or less for the compound containing a basic functional group. The amount of the dispersant added is preferably 75 parts or more and 1000 parts or less with respect to 100 parts by weight of the carbon nanotubes (hereinafter, “parts by weight” is simply abbreviated as “parts”). If it is less than 75 parts, the dispersion stability is poor. When the addition amount exceeds 1000 parts, the haze tends to increase. The dispersing agent that can be used is preferably one containing a basic functional group. For example, Solspers 24000SC, 24000GR, 32500, 32550, 32600, 33000, 34500, 34750, 35200, 37500, 39000, etc. manufactured by Abycia, etc. , 180, 187, etc., and Kao Amit 105, 302, and the like. In addition, a silane coupling agent, a titanate coupling agent, an aluminum coupling agent, etc. can also be used conveniently.

  The carbon nanotube used in the present invention preferably has a crystallinity of 0.70 or more and 1.50 or less. When a crystallinity higher than 1.50 is used, the dispersion stability is poor. On the other hand, when a value smaller than 0.70 is used, the electric resistance value becomes high. Examples of such carbon nanotubes include C-Tube 100 and 300 manufactured by CNT. Such a carbon nanotube can be produced by a conventionally known method such as a thermal CVD method using a metal catalyst such as iron.

  The binder used in the present invention is preferably a so-called oligomer or monomer. A combination of these may be used. The molecular weight is preferably 15000 or less. For example, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa ( And radiation curable monomers such as (meth) acrylate. Further, dipentaerythritol modified with caprolactone and (meth) acrylated, for example, DPCA-60, DPCA-90, DPCA-120 manufactured by Nippon Kayaku Co., Ltd. may be used. You may use a meth) acrylate. Examples of radiation curable oligomers include Art Resins UN-3320HA, UN-3320HB, UN-3320HC, UN-3320HS, and the like manufactured by Negami Kogyo Co., Ltd. Such oligomers and monomers may be used alone or in combination. The amount of the binder added is preferably 100 parts or more and 90000 parts or less with respect to 100 parts of the carbon nanotubes. If the binder is less than 100 parts, the haze increases because the amount of carbon nanotubes in the coating film is large. On the other hand, when the amount is more than 90000 parts, the effect of reducing the surface electrical resistance is inferior.

In the present invention, when a radiation curable oligomer or monomer is used as the binder, gamma rays, electron beams or ultraviolet rays can be preferably used for curing. In particular, it is convenient to use ultraviolet rays. As a light source for ultraviolet irradiation, a high pressure mercury lamp, a metal halide lamp, an ultraviolet LED lamp or the like is used. Irradiation energy is preferably ^{100~2000mJ / cm 2, 150~1000mJ / cm} 2 is more preferable. When ultraviolet rays are used, it is necessary to include an ultraviolet curing initiator in the coating film. For example, benzoin isopropyl ether, benzophenone, 2-hydroxy-2-methylpropiophenone, 1-hydroxycyclohexyl phenyl ketone, 2, 4 -Diethylthioxanthone, methyl o-henzoylbenzoate, 4,4-bisdiethylaminobenzophenone, 2,2-diethoxyacetophene, benzyl, 2-chlorothioxanthone, diisopropylthioxanthone, 9,10-anthraquinone, benzoin, benzoin Methyl ether, 2,2-dimethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-propiophenone, 4-isopropyl-2-hydroxy-2-methylpropiophenone, α, α-dimethoxy-α-phenyla Tons, 1- [4- (2-hydroxyethoxy) - phenyl] -2-hydroxy-2-methyl-1-and the like are preferably used. When such an ultraviolet curing initiator is included, the added amount is preferably 2 parts or more and 20 parts or less, with the total amount of binder and dispersant being 100 parts. When it is less than 2 parts, the curability is inferior, and when it is more than 20 parts, haze may be increased.

  Examples of the organic solvent in the present invention include ketone solvents such as MEK, MIBK, and cyclohexanone, aromatic solvents such as toluene and xylene, aliphatic solvents such as hexane and octane, alcohol solvents such as methanol, ethanol, and propanol. Are preferably used alone or in combination. As is well known, the concentration of solids such as carbon nanotubes, dispersants, and binders depends on the dispersion method, coating method, etc., and cannot be determined in general. However, when dispersed, the carbon nanotubes are preferably 10% by weight or less, more preferably 2.5% by weight or less. When the amount is more than 10% by weight, the viscosity becomes high and the dispersion becomes difficult, and the haze tends to increase.

  The carbon nanotube dispersion liquid of the present invention may be produced by dispersion treatment by a conventionally known method such as a bead mill such as a sand grinder mill, an ultrasonic disperser, or an attritor. In particular, it is preferable to use an ultrasonic disperser in order to disperse the carbon nanotube without damaging it.

  The carbon nanotube coating film of the present invention is obtained by following a conventionally known method for the dispersion, for example, spin coating method, dip coating method, bar coating method, blade coating method, air knife coating method, roll coating method, screen printing method, spraying. After coating on a substrate by a coating method or the like, it can be formed by irradiating with radiation and curing. The coating thickness of the carbon nanotube is preferably 0.01 μm or more and 100 μm or less, and more preferably 0.05 μm or more and 20 μm or less. If the thickness is less than 0.01 μm, the coating film is easily damaged, and if it exceeds 100 μm, the sheet tends to be warped. As the substrate, a polyester film such as PET or polyethylene naphthalate (PEN), a cellulose film such as triacetyl cellulose, a polyamide film such as nylon, or a polyamide-imide film may be used.

“Composition A1”
・ Carbon nanotubes (CNT-made C-Tube 100) 1.0 part ・ Basic functional group-containing compound 2.5 parts (Avisia Corporation Solspurs 37500 solid content 40 wt%)
MEK 38.25 parts Toluene 19.13 parts Cyclohexanone 19.13 parts

  The composition A1 was mixed and stirred and then subjected to ultrasonic treatment to obtain a primary dispersion. The ultrasonic treatment was performed using an ultrasonic homogenizer “UH-600 type” manufactured by SMT. Next, the following composition B1 was mixed and stirred, and added to 100 parts of the primary dispersion to obtain a carbon nanotube dispersion 1. In the case of Example 1, the addition amount of the following composition B1 with respect to 100 parts of the primary dispersion is the total amount (401.88 parts) of the components of the following composition B1 (also in the following Example 2 and the like). )

“Composition B1”
Compound having a molecular weight of 15000 or less (DPHA manufactured by Nippon Kayaku Co., Ltd.) 42.63 parts UV initiator (Irgacure 907 manufactured by Ciba) 4.88 parts MEK 177.19 parts Toluene 88.59 parts Cyclohexanone 88.59 Part

“Composition A2”
Carbon nanotube (C-Tube 100 manufactured by CNT) 1.0 part Compound containing a basic functional group 22.25 parts (Solspurs 37500 manufactured by Avicia Co., solid content 40% by weight)
MEK 28.25 parts Toluene 14.13 parts Cyclohexanone 14.13 parts

  The composition A2 was mixed and stirred and then subjected to ultrasonic treatment to obtain a primary dispersion. The ultrasonic treatment was performed using an ultrasonic homogenizer manufactured by SMT. Next, the following composition B2 was mixed and stirred, and added to 100 parts of the primary dispersion to obtain a carbon nanotube dispersion 2.

“Composition B2”
Compound having a molecular weight of 15000 or less (PE-3A manufactured by Nippon Kayaku Co., Ltd.) 383.40 parts UV initiator (Irgacure 907 manufactured by Ciba) 20.77 parts MEK 6.35 parts Toluene 3.18 parts Cyclohexanone 3 .18 parts

“Composition A3”
・ Carbon nanotube (Sankyo Chemical Co., Ltd. 100G) 1.0 part ・ Compound containing basic functional group 1.88 parts (Avisia Corporation Solspurs 32500 solid content 40 wt%)
MEK 115.23 parts Toluene 57.61 parts Cyclohexanone 57.61 parts

  The composition A3 was mixed and stirred and then subjected to ultrasonic treatment to obtain a primary dispersion. The ultrasonic treatment was performed using an ultrasonic homogenizer manufactured by SMT. Next, the following composition B3 was mixed and stirred, and added to 100 parts of the primary dispersion to obtain a carbon nanotube dispersion 3.

“Composition B3”
Compound with a molecular weight of 15000 or less 1.74 parts (UN-3320HA manufactured by Negami Kogyo Co., Ltd.)
-UV initiator (Irgacure 907 manufactured by Ciba) 0.36 parts-MEK 56.33 parts-Toluene 28.17 parts-Cyclohexanone 28.17 parts

“Composition A4”
Carbon nanotube (C-Tube 100 manufactured by CNT) 1.0 part Compound containing a basic functional group 1.5 parts (Solspurs 32500 manufactured by Avicia Co., solid content 40% by weight)
MEK 105.42 parts Toluene 52.71 parts Cyclohexanone 52.71 parts

  The composition A4 was mixed and stirred, and then subjected to ultrasonic treatment to obtain a primary dispersion. The ultrasonic treatment was performed using an ultrasonic homogenizer manufactured by SMT. Subsequently, the following composition B4 was mixed and stirred, and added to 100 parts of the primary dispersion to obtain a carbon nanotube dispersion 4.

“Composition B4”
Compound having a molecular weight of 15000 or less (DPHA manufactured by Nippon Kayaku Co., Ltd.) 16.17 parts UV initiator (Irgacure 907 manufactured by Ciba) 1.83 parts MEK 34.96 parts Toluene 17.48 parts Cyclohexanone 17.48 Part

[Comparative Example 1]
“Composition A5”
・ Carbon nanotube (L.SWNT manufactured by NTP) 1.0 part ・ Compound containing basic functional group 10.5 parts (SOLVIS 32500 manufactured by Avicia Co., solid content 40% by weight)
MEK 109.25 parts Toluene 54.63 parts Cyclohexanone 54.63 parts

  The above composition was mixed and stirred, and then subjected to ultrasonic treatment to obtain a primary dispersion. The ultrasonic treatment was performed using an ultrasonic homogenizer manufactured by SMT. Next, the following composition B5 was mixed and stirred, and added to 100 parts of the primary dispersion to obtain a carbon nanotube dispersion 5.

“Composition B5”
Compound having a molecular weight of 15000 or less (DPHA manufactured by Nippon Kayaku Co., Ltd.) 10.70 parts UV initiator (Irgacure 907 manufactured by Ciba) 1.70 parts MEK 52.50 parts Toluene 26.25 parts Cyclohexanone 26.25 Part

[Comparative Example 2]
“Composition A6”
Carbon nanotube (XD Grade manufactured by CNI Co., Ltd.) 1.0 part Compound containing basic functional group 2.5 parts (Solspurs 32500 manufactured by Avicia Co., solid content 40% by weight)
MEK 78.25 parts Toluene 39.13 parts Cyclohexanone 39.13 parts

  The composition A6 was mixed and stirred, and then subjected to ultrasonic treatment to obtain a primary dispersion. The ultrasonic treatment was performed using an ultrasonic homogenizer manufactured by SMT. Next, the following composition B6 was mixed and stirred, and added to 100 parts of the primary dispersion to obtain a carbon nanotube dispersion 6.

“Composition B6”
Compound having a molecular weight of 15000 or less (DPHA, Nippon Kayaku Co., Ltd.) 21.31 parts UV initiator (Irgacure 907, Ciba) 2.44 parts MEK 63.59 parts Toluene 31.80 parts Cyclohexanone 31.80 Part

<< Evaluation of carbon nanotube dispersion liquid >>
30 g of the carbon nanotube dispersion liquid obtained in each of the above Examples and Comparative Examples was placed in a screw tube bottle with a capacity of 50 ml, left in a cool dark place for one day, and dispersion stability was determined depending on whether sediment was formed on the bottle bottom. It was confirmed. Table 1 shows the characteristics of the carbon nanotubes used in each Example and Comparative Example and the observation results of the bottle bottom.

  In Table 1, Examples 1, 2 and 3 used carbon nanotubes having a diameter of 10 to 50 nm and a crystallinity of 0.70 to 1.50, so that the dispersion stability was good. In Example 4, since the addition amount of the compound having a basic functional group was less than 75% with respect to the carbon nanotube, the dispersion stability was inferior. Since Comparative Example 1 and Comparative Example 2 had a diameter of less than 10 nm or crystallinity greater than 1.5, the dispersion stability was extremely inferior.

[Reference Example 1]
The dispersion 1 is centrifuged (3000 G / 5 minutes), applied to a PET film having a thickness of 100 μm using a wire bar, dried at 90 ° C., and then irradiated with ultraviolet rays (200 mJ / cm ² ) to form a coating film 1 Got.

[Reference Example 2]
The dispersion 2 is centrifuged (3000 G / 5 minutes), applied to a PET film having a thickness of 100 μm using a wire bar, dried at 90 ° C., and then irradiated with ultraviolet rays (200 mJ / cm ² ) to form a coating film 2 Got.

[Reference Example 3]
The dispersion 3 is centrifuged (3000 G / 5 min), applied to a PET film having a thickness of 100 μm using a wire bar, dried at 90 ° C., irradiated with ultraviolet rays (200 mJ / cm ² ), and the coating film 3 Got.

[Reference Example 4]
“Composition A7”
Carbon nanotube (C-Tube 200 manufactured by CNT) 1.0 part Compound containing a basic functional group (Solspers 37500, solid content 40% by weight manufactured by Avicia) 1.88 parts MEK 38.25 parts Toluene 19.13 Parts ・ Cyclohexanone 19.13 parts

  The composition A7 was mixed and stirred, and then subjected to ultrasonic treatment to obtain a primary dispersion. The ultrasonic treatment was performed using an ultrasonic homogenizer manufactured by SMT. Next, the following composition B7 was mixed and stirred, and added to 100 parts of the primary dispersion to obtain a carbon nanotube dispersion 7.

“Composition B7”
Compound having a molecular weight of 15000 or less (DPHA manufactured by Nippon Kayaku Co., Ltd.) 36.78 parts UV initiator (Irgacure 907 manufactured by Ciba) 10.73 parts MEK 177.19 parts Toluene 88.59 parts Cyclohexanone 88.59 Part

The obtained carbon nanotube dispersion 7 was centrifuged (3000 G / 5 minutes), applied to a PET film having a thickness of 100 μm using a wire bar, dried at 90 ° C., and then irradiated with ultraviolet rays (200 mJ / cm ² ). A coating film 4 was obtained.

[Reference Example 5]
“Composition A8”
・ Carbon nanotubes (C-Tube 100 manufactured by CNT) 1.0 part ・ Compound containing basic functional group 10.5 parts (Solspurs 24000 manufactured by Avicia Co., solid content: 100% by weight)
MEK 40.25 parts Toluene 20.13 parts Cyclohexanone 20.13 parts

  The composition A8 was mixed and stirred, and then subjected to ultrasonic treatment to obtain a primary dispersion. The ultrasonic treatment was performed using an ultrasonic homogenizer manufactured by SMT. Next, the following composition B8 was mixed and stirred, and added to 100 parts of the primary dispersion to obtain a carbon nanotube dispersion 8.

“Composition B8”
Compound having a molecular weight of 15000 or less (TMPTA manufactured by Nippon Kayaku Co., Ltd.) 1020.16 parts UV initiator (Irgacure 907 manufactured by Ciba) 54.29 parts MEK 33.89 parts Toluene 16.94 parts Cyclohexanone 16.94 Part

The obtained carbon nanotube dispersion 8 was centrifuged (3000 G / 5 min), applied to a PET film having a thickness of 100 μm using a wire bar, dried at 90 ° C., and then irradiated with ultraviolet rays (200 mJ / cm ² ). A coating film 3 was obtained.

[Reference Example 6]
“Composition A9”
Carbon nanotube (C-Tube 100 manufactured by CNT) 1.0 part Compound containing a basic functional group 2.50 parts (Solspers 37500 manufactured by Avicia Co., solid content 40% by weight)
MEK 38.25 parts Toluene 19.13 parts Cyclohexanone 19.13 parts

  The composition A9 was mixed and stirred, and then subjected to ultrasonic treatment to obtain a primary dispersion. The ultrasonic treatment was performed using an ultrasonic homogenizer manufactured by SMT. Next, the following composition B9 was mixed and stirred, and added to 100 parts of the primary dispersion to obtain a carbon nanotube dispersion 9.

“Composition B9”
-High molecular compound (BL-S molecular weight 23000 manufactured by Sekisui Chemical Co., Ltd.) 47.50 parts-MEK 177.19 parts-Toluene 88.59 parts-Cyclohexanone 88.59 parts

The obtained carbon nanotube dispersion 9 is centrifuged (3000 G / 5 minutes), applied to a 100 μm thick PET film using a wire bar, dried at 90 ° C., and then irradiated with ultraviolet rays (200 mJ / cm ² ). A coating film 6 was obtained.

<< Evaluation for coating film >>
About each coating film obtained by Reference Examples 1-6, the total light transmittance, haze, and surface electrical resistance were measured, respectively. Table 2 shows the results.
-Total light transmittance and haze: V-570 spectrophotometer manufactured by JASCO Corporation-Surface electrical resistance: HIRESTA manufactured by Mitsubishi Yuka Co., Ltd.

  Each coating film according to Reference Examples 1 to 3 was obtained by applying the carbon nanotube dispersion liquid of the present invention. As can be seen from Table 2, the haze and the surface electrical resistance are relatively low. The carbon nanotube used in Reference Example 4 was obtained by oxidizing the carbon nanotube used in Example 1, and had a diameter of 19 nm and a crystallinity of 1.52. Moreover, since there is much addition amount of UV initiator, haze and surface electrical resistance are high. The coating film according to Reference Example 5 has a high haze and surface electrical resistance because it uses a large amount of dispersant and a large amount of UV monomer. The coating film according to Reference Example 6 has a high surface electrical resistance because a compound having a molecular weight of greater than 15000 was used.

Claims (4)

A carbon nanotube dispersion obtained by dispersing carbon nanotubes in a solvent,
A carbon nanotube dispersion liquid comprising carbon nanotubes having a diameter of 10 to 50 nm, a compound containing a basic functional group, a compound having a molecular weight of 15000 or less, and a ketone solvent. The crystallinity of the carbon nanotube is 0.70 to 1.50,
The compound containing the basic functional group is a dispersant,
The carbon nanotube dispersion liquid according to claim 1, wherein the compound having a molecular weight of 15000 or less is a compound containing at least one of an acryl group and a methacryl group.   The compound containing the basic functional group is contained in an amount of 75 to 1000 parts by weight, and the compound containing at least one of an acryl group and a methacryl group is contained in an amount of 100 to 90000 parts by weight with respect to 100 parts by weight of the carbon nanotube. 2. The carbon nanotube dispersion liquid according to 2.   The carbon nanotube coating film formed by apply | coating the carbon nanotube dispersion liquid in any one of Claim 1 thru | or 3 on a base material.