阅读说明：本技术 碳纳米管分散液 (Carbon nanotube dispersion liquid ) 是由 山田纯也 近田安史 岩佐成人 竹中芽衣 小田实生 于 2019-09-27 设计创作，主要内容包括：本发明的课题在于,提供一种用于制成具有高透明性及低表面电阻值的成形体的碳纳米管的分散液、使用所述分散液的含碳纳米管的组合物。在使热重量测定中的至900℃的加热重量减少率为80％以上、拉曼光谱测定中的G/D比为30以上的碳纳米管(A)分散于分散介质(B)时,利用具有特定的费雷特长度的分散液、使用所述分散液的含碳纳米管的组合物,可得到具有高透明性及低表面电阻值的成形体。(The invention provides a dispersion liquid of carbon nanotubes for producing a molded body having high transparency and low surface resistance, and a composition containing carbon nanotubes using the dispersion liquid. When carbon nanotubes (A) having a heating weight loss rate of 80% or more at 900 ℃ in thermogravimetric measurement and a G/D ratio of 30 or more in Raman spectroscopy are dispersed in a dispersion medium (B), a molded body having high transparency and low surface resistance can be obtained by using a dispersion having a specific Feret length and a composition containing carbon nanotubes using the dispersion.)

1. A dispersion liquid which is a dispersion liquid of carbon nanotubes (A) and a dispersion medium (B),

the carbon nanotube (A) has a heating weight loss rate of 80% or more at 900 ℃ in thermogravimetric measurement and a G/D ratio of 30 or more in Raman spectroscopic measurement,

the dispersion satisfies the following condition (1):

(1) in the carbon nanotube, the ratio of particles having a Ferrett length of 50 μm or more to all the particles is 5% or less.

2. The dispersion liquid according to claim 1,

the carbon nanotubes (A) have an average Ferrett length of 0.8 to 75 μm.

3. The dispersion liquid according to claim 1 or 2,

the carbon nanotube (A) has a G/D ratio of 90 or more in Raman spectroscopy measurement.

4. A carbon nanotube-containing composition comprising the dispersion liquid according to any one of claims 1 to 3 and a resin (C).

5. The carbon nanotube-containing composition according to claim 4,

the resin (C) has a total light transmittance of 80% or more when the thickness is 10mm or less.

6. A shaped body of the carbon nanotube-containing composition according to claim 4 or 5.

7. The shaped body according to claim 6, wherein,

the molded article had a volume resistance of 5.0X 10¹⁰Omega cm or less, and a total light transmittance of 5% or more when the thickness is 1 mm.

8. The shaped body according to claim 6, wherein,

the molded article had a surface resistance of 1.0X 10¹³Omega/sq.

Technical Field

The present invention relates to a dispersion of carbon nanotubes, a composition containing carbon nanotubes using the dispersion, and a molded body of the composition containing carbon nanotubes.

Background

Carbon nanotubes are tubular materials having a diameter of a nanometer size and composed of only carbon atoms, and are drawing attention because of characteristics such as electrical conductivity, thermal conductivity, mechanical strength, and chemical properties derived from the characteristics of their structures, and practical use in various applications, including the electronic field and the energy field, is being studied.

There are various types of carbon nanotubes, including single-walled carbon nanotubes (hereinafter abbreviated as SWNTs) incorporated in a single layer, multi-walled carbon nanotubes (hereinafter abbreviated as MWNTs), double-walled nanotubes (hereinafter abbreviated as DWNTs) included in a double-walled carbon nanotube (hereinafter abbreviated as DWNTs), and the like; in addition, there are carbon nanotubes with both ends capped, carbon nanotubes with one end capped, carbon nanotubes with both ends open; as a configuration for rounding, there are various types of configurations such as an armchair type.

However, since the carbon nanotubes are long tubular, they are tangled and formed into irregular linear clusters (Japanese-Yuan-Ju). Therefore, it is a great problem whether the carbon nanotubes can be dispersed and stabilized.

Specifically, when carbon nanotubes are kneaded with a resin or the like, the dispersion may be insufficient, and the performance according to the amount of the carbon nanotubes added may not be sufficiently exhibited due to poor dispersion.

For example, patent documents 1 and 2 describe the state of dispersion of carbon nanotubes in a resin, but do not describe in detail a specific method for dispersion.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2006-

Patent document 2: japanese patent laid-open No. 2008-308583

Disclosure of Invention

Problems to be solved by the invention

The present invention addresses the problem of providing a dispersion of carbon nanotubes for producing a molded body having high transparency and a low surface resistance value, and a composition containing carbon nanotubes using the dispersion.

Means for solving the problems

The present inventors have made various studies to solve the above problems, and as a result, have found that: when the carbon nanotubes (A) having a heating weight loss rate of 80% or more at 900 ℃ in thermogravimetric measurement and a G/D ratio of 30 or more in Raman spectroscopy are dispersed in a dispersion medium (B), a molded body having high transparency and low surface resistance can be obtained by using a dispersion having a specific Feret length (Japanese text: フェレー long) and a composition containing carbon nanotubes using the dispersion.

That is, the present invention can be described as follows.

Item 1, a dispersion liquid which is a dispersion liquid of carbon nanotubes (A) and a dispersion medium (B), wherein,

the carbon nanotube (A) has a heating weight loss rate of 80% or more at 900 ℃ in thermogravimetric measurement and a G/D ratio of 30 or more in Raman spectroscopic measurement,

the dispersion satisfies the following condition (1):

(1) in the carbon nanotube, the ratio of particles having a Ferrett length of 50 μm or more to all the particles is 5% or less.

Item 2 the dispersion liquid according to item 1, wherein,

the carbon nanotubes (A) have an average Ferrett length of 0.8 to 75 μm.

Item 3, the dispersion liquid according to item 1 or 2, wherein,

the carbon nanotube (A) has a G/D ratio of 90 or more in Raman spectroscopy measurement.

Item 4 is a carbon nanotube-containing composition comprising the dispersion liquid according to any one of items 1 to 3 and a resin (C).

Item 5 the carbon nanotube-containing composition according to item 4, wherein,

the resin (C) has a total light transmittance of 80% or more when the thickness is 10mm or less.

Item 6, a shaped body of the carbon nanotube-containing composition according to item 4 or 5.

The molded article of item 7 or 6, wherein,

the molded article had a volume resistance of 5.0X 10¹⁰Omega cm or less, and a total light transmittance of 5% or more when the thickness is 1 mm.

The molded article of item 8 or 6, wherein,

the molded article had a surface resistance of 1.0X 10¹³Omega/sq.

Effects of the invention

Since the dispersion liquid of the present invention can achieve high dispersibility when containing a resin, a molded article produced from a carbon nanotube-containing composition containing a dispersion liquid and a resin has high transparency and low surface resistance, and is useful in various fields such as electric devices, machine parts, and automobile parts.

Drawings

FIG. 1 shows the distribution of Ferrett lengths of the dispersions of examples 1 and 2 and comparative examples 1 and 2.

Detailed Description

[1. Dispersion ]

The dispersion liquid of the present invention is a dispersion liquid of a carbon nanotube (A) and a dispersion medium (B), wherein the rate of weight loss by heating to 900 ℃ in thermogravimetric measurement is 80% or more, and the G/D ratio in Raman spectroscopy is 30 or more. That is, the dispersion liquid of the present invention is a dispersion liquid containing the carbon nanotubes (a) and the dispersion medium (B). In the present invention, "carbon nanotube" may be referred to as "CNT".

The carbon nanotubes (a) in the dispersion liquid of the present invention have a heating weight loss rate at 900 ℃ of 80% or more, preferably 90% or more, and particularly preferably 98% or more, as measured from 30 ℃ at a temperature rise rate of 10 ℃/min in thermogravimetry.

In the carbon nanotubes (a) in the dispersion liquid of the present invention, in the thermogravimetric measurement, the ratio of the rate of decrease in the heating weight at 500 ℃ measured under the condition from 30 ℃ and at a temperature increase rate of 10 ℃/min to the rate of decrease in the heating weight at 900 ℃ measured under the condition from 30 ℃ and at a temperature increase rate of 10 ℃/min is preferably 20% or less, preferably 15% or less, and particularly preferably 10% or less.

The intensity ratio G/D of the G band and D band of the carbon nanotubes (a) in the dispersion liquid of the present invention is 30 or more, preferably 50 or more, more preferably 90 or more, and particularly preferably 100 or more. G/D is the G band (1590 cm) in the Raman spectrum measured by resonance Raman Scattering (excitation wavelength 532nm) measured with a Raman spectrometer^-1Nearby) and D band (1300 cm)^-1Near) is calculated. The higher the G/D ratio, the smaller the amount of defects in the structure of the carbon nanotube.

The diameter of the carbon nanotube (A) is not particularly limited, and the diameter of the carbon nanotube is preferably in the range of 0.4 to 10nm, particularly preferably 1.0 to 5.0 nm.

The surface and the end of the carbon nanotube may be modified with a functional group or an alkyl group. Examples of the functional group include a carboxyl group and a hydroxyl group.

The carbon nanotubes (a) in the dispersion liquid of the present invention may be single-walled carbon nanotubes or multi-walled carbon nanotubes, but single-walled carbon nanotubes are preferable, and single-walled carbon nanotubes are preferable in which 60% or more of the carbon nanotubes are preferable.

The source of the carbon nanotubes (a) in the dispersion of the present invention is not limited, and any production method may be used, and examples thereof include an arc discharge method, a laser evaporation method, and a Chemical Vapor Deposition (CVD) method, and preferably a Chemical Vapor Deposition (CVD) method. The Chemical Vapor Deposition (CVD) method may be exemplified by a vapor flow method and a substrate growth method, and is preferably a vapor flow method.

In the dispersion liquid of the present invention, the ratio of particles having a Firedt length of 50 μm or more to all particles observed in the range of 0.8 μm to 1000 μm in the carbon nanotubes is 5% or less, preferably 3% or less, and particularly preferably 2% or less.

In the dispersion liquid of the present invention, the average Ferrett length of the carbon nanotubes observed in the range of 0.8 μm to 1000 μm is preferably 0.8 μm or more, preferably 5 μm or more, more preferably 10 μm or more, particularly preferably 20 μm or more, preferably 75 μm or less, and particularly preferably 50 μm or less.

In the present invention, the "Ferrett length" is defined as the Ferrett diameter orthogonal to the minimum Ferrett diameter of the particles (Japanese text: フェレー diameter), and the measurement is carried out by an image analysis particle size distribution meter.

In the present invention, the following method can be exemplified as a method for measuring the ferter length.

An image was taken with a 660-thousand pixel camera while circulating the dispersion using an image analysis particle size distribution meter (product name: CF-3000 manufactured by JASCO International Co., Ltd.), and the particle diameter of particles in the range of 0.8 μm to 1mm was measured. 0.02mL of the dispersion was diluted with isopropanol to give a carbon nanotube concentration of 3X 10^-5The flow rate was 150mL, and a 0.1mL portion of the flow rate was measured.

In the present invention, the distribution of the carbon nanotube particles observed is represented by a histogram in which the volume fraction is taken on the vertical axis. In the Ferrett length distribution, the proportion of the Ferrett length of 50 μm or more was evaluated.

In the present invention, the average Firett length can be calculated as the Firett length at 50% volume fraction cumulative value from 0.8 μm in the distribution measurement of the image analysis particle size distribution of 0.8 μm to 1000 μm, and determined as an average value of 3 times.

In the dispersion liquid of the present invention, the content of the carbon nanotubes (a) is not particularly limited, but is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and particularly preferably 0.2% by mass or more; preferably 1.0% by mass or less, more preferably 0.5% by mass or less, and particularly preferably 0.3% by mass or less. By setting these ranges, the dispersibility of the carbon nanotubes and the use of the dispersion liquid are preferable.

The dispersion medium (B) in the dispersion liquid of the present invention is not particularly limited as long as it can disperse the carbon nanotubes (A), and the shear viscosity of 100[1/S ] of the solvent at 30 ℃ is preferably 1[ mPas ] or more, more preferably 10[ mPas ] or more; preferably 200[ mPaS ] or less. Although not particularly limited, the dissolution parameter calculated from the calculation formula of Fedors is preferably in the range of 7 to 25, and more preferably in the range of 8 to 20.

The dispersion medium (B) in the dispersion liquid of the present invention is not particularly limited, and examples thereof include a dispersion medium containing any one of water, a halogen-based solvent, an alcohol, a phenol, an amide, an allyl, a ketone, and a plasticizer for rubber, or a mixed dispersion medium of at least 2 kinds or more thereof.

Examples of the halogen-based solvent include chloroform and dichloromethane. Examples of alcohols include: methanol, ethanol, isopropanol, n-butanol, polycarbonate diol, and the like. Examples of the phenols include bisphenols, trisphenols, polyphenols, and the like. Examples of amides include: n-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, 1, 3-dimethyl-2-imidazolidinone, N-dimethylformamide, N-diethylformamide, N-dimethylacetamide, N-diethylacetamide, and dimethyl sulfoxide. Examples of the allyl group include: diallyl phthalate, triallyl trimesate, triallyl trimellitate, 1,3,5, 7-tetraallylnaphthalene, and the like. In addition, examples of ketones include: acetone, methyl ethyl ketone, methyl isobutyl ketone, and the like. Examples of the plasticizer for rubber include: phthalic acid derivatives, tetrahydrophthalic acid derivatives, adipic acid derivatives, azelaic acid derivatives, sebacic acid derivatives (ドデカン -2-acid crystal in the japanese text), maleic acid derivatives, fumaric acid derivatives, trimellitic acid derivatives, pyromellitic acid derivatives, citric acid derivatives, oleic acid derivatives, ricinoleic acid derivatives, stearic acid derivatives, fatty acid derivatives, sulfonic acid derivatives, phosphoric acid derivatives, glutaric acid derivatives, glycolic acid derivatives, glycerin derivatives, paraffin derivatives, epoxy derivatives, monoester plasticizers, polyester plasticizers, polyether plasticizers, paraffin mineral oils, naphthene mineral oils, aromatic mineral oils, vegetable oil plasticizers, other plasticizers, and the like.

In the dispersion liquid of the present invention, a dispersant may be added as needed. The dispersant is not particularly limited, and specifically, the following may be exemplified: polymer dispersants such as carboxymethyl cellulose, polyvinyl butyral, polyvinyl pyrrolidone, and polyvinyl acetal; and low molecular weight dispersants such as sodium fatty acid, potassium fatty acid, sodium alkylbenzenesulfonate, sodium alkylnaphthalenesulfonate, sodium alkylsulfate, sodium alkylsulfonate, sodium alkylethersulfate, monoalkyl phosphate, sodium polyoxyethylene alkyletherphosphate, sodium fatty acid ester sulfonate, sodium fatty acid ester sulfate, sodium fatty acid alkylolamide sulfate (Japanese text: fatty acid アルキロースアミド sulfuric acid エステルナトリウム), sodium fatty acid amide sulfonate, polyoxyethylene alkylether, polyoxyethylene alkylaryl ether, alkylmethylammonium chloride, alkyltrimethylammonium chloride, dialkyldimethylammonium chloride, alkyldimethylbenzylammonium chloride, and alkylpyridinium chloride. The content of the dispersant is not particularly limited, and is preferably 10 parts by mass or more, more preferably 50 parts by mass or more, and particularly preferably 100 parts by mass or more, per 100 parts by mass of the carbon nanotube (a); preferably 1000 parts by mass or less, more preferably 500 parts by mass or less, and particularly preferably 300 parts by mass or less.

The dispersion of the present invention can be produced by a homogenizer, a bead mill, a ball mill, a basket mill, an attritor, a universal mixer, a transparent mixer (Japanese text: クリアミキサー), an ultrasonic wave, a jet mill, a shear dispersion treatment, or the like.

For the shear dispersion treatment, a device such as "Nano Jet Pul JN 20" (manufactured by JOKOH Co., Ltd.) or "Nanovater L-ES" (manufactured by Yoshida KIKAI CO., LTD) may be used.

[2. composition containing carbon nanotubes ]

The carbon nanotube-containing composition of the present invention contains the dispersion liquid and the resin (C).

Examples of the resin (C) of the present invention include: styrene resins such as polystyrene resin and ABS resin, acrylic resins, polyvinyl chloride resins, polymethylpentene resins, syndiotactic polystyrene resins, polyacetal resins, polyamide resins, polyethylene terephthalate resins, polyethylene naphthalate resins, polyimide resins, polyphenylene sulfide resins, aromatic polyamide resins, polylactic acids, polycarbonate resins, polyacrylonitrile resins, polymethyl methacrylate resins, alicyclic acrylic resins, polyethylene resins, polypropylene resins, olefin resins such as cycloolefin resins, modified polyphenylene ether resins, polyphenylene sulfide resins, polyamideimide resins, polyether sulfone resins, polysulfone resins, polyether ether ketone resins, liquid crystal resins, aromatic polyimide resins, epoxy resins, phenol resins, fluorine resins, silicone resins, and the like. These resins may be used alone in 1 kind, or in combination in 2 or more kinds.

The resin (C) of the present invention is preferably a resin having a total light transmittance of 80% or more when the thickness is 10mm or less, and examples thereof include styrene resins, acrylic resins, polyvinyl chloride resins, olefin resins, and polycarbonate resins. The upper limit of the total light transmittance is not particularly limited, and is 99% or less. The total light transmittance was measured according to JIS K7361-1. Specifically, the calculation can be performed using an ultraviolet-visible spectrophotometer or the like.

The content of the carbon nanotubes (a) in the carbon nanotube-containing composition of the present invention is preferably 0.001 parts by mass or more, more preferably 0.005 parts by mass or more, and still more preferably 0.01 parts by mass or more per 100 parts by mass of the resin (C); further, it is preferably 10 parts by mass or less, more preferably 1.0 part by mass or less, and still more preferably 0.05 part by mass or less.

In the carbon nanotube-containing composition of the present invention, a conductive aid may be contained. The conductive aid is not particularly limited, and a general conductive aid can be used. Examples of the conductive polymer include, for example, natural graphite, graphite such as artificial graphite, carbon black such as acetylene black, ketjen black, and furnace black, carbon materials such as graphene and fullerene, metal powders such as copper and nickel, metal fibers, polyaniline, polypyrrole, polythiophene, polyacetylene, and a polystyrene derivative (japanese original: ポリフェニレン誘導体) which are electron conductive materials. These substances may be used alone in 1 kind, or may be used in combination in 2 or more kinds.

The carbon nanotube-containing composition of the present invention may contain other compounding agents as long as the effects of the present invention are not impaired, and examples thereof include: antioxidants, heat stabilizers, light stabilizers, ultraviolet absorbers, crosslinking agents, pigments, colorants, foaming agents, antistatic agents, flame retardants, lubricants, softeners, tackifiers, plasticizers, mold release agents, odor inhibitors, perfumes, and the like.

The carbon nanotube-containing composition of the present invention can be produced by mixing (kneading) various materials, and examples of the mixing (kneading) method include, but are not particularly limited to, melt-kneading methods using a mixer such as an open roll, an intensive mixer, an internal mixer, a reciprocating kneading extruder (japanese laid-open: コニーダー), a continuous kneader with a twin-screw rotor, or an extruder. As the extruder, either a single-screw or twin-screw extruder may be used.

[3. molded article ]

The molded body of the carbon nanotube-containing composition of the present invention is obtained by molding the above carbon nanotube-containing composition. For the formation of the carbon nanotube-containing composition, for example, injection molding, injection compression molding, extrusion molding, blow molding, inflation molding, vacuum molding, press molding, cast film molding, and the like can be used.

The molded article of the present invention preferably has a volume resistance value of 5.0X 10¹⁰Omega. cm, more preferably 1.0X 10⁹Omega cm or less, more preferably 1.0X 10⁸Omega cm or less, particularly preferably 1.0X 10⁷Omega cm or less. The lower limit is not particularly limited, and is, for example, 1.0X 10. omega. cm or more.

The surface resistance of the molded article of the present invention is preferably 1.0X 10¹³Omega/sq. or less, more preferably 1.0X 10¹²Omega/sq. or less, particularly preferably 5.0X 10¹¹Omega/sq. The lower limit is not particularly limited, and is 1.0X 10³Omega/sq.

The transmittance of the molded article of the present invention is preferably 5% or more, more preferably 10% or more, and particularly preferably 20% or more of the total light transmittance at a thickness of 1 mm. The upper limit is not particularly limited, and is 80% or less. The total light transmittance was measured according to JIS K7361-1. Specifically, the calculation can be performed using an ultraviolet-visible spectrophotometer or the like.

Examples

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples within the scope not exceeding the gist thereof. In the following examples and comparative examples, the blending amount means parts by mass.

The evaluation of the carbon nanotubes (a) was performed using the following analysis apparatus.

(thermogravimetric analysis)

About 7mg of the test specimen was heated from 30 ℃ to 900 ℃ at a temperature rising rate of 10 ℃/min with an air flow rate of 200 cc/min using a thermogravimetric/differential thermal analyzer (Hitachi High-Tech Science Corporation STA7200RV), and the weight reduction ratio in the temperature range of 30 ℃ to 900 ℃ was evaluated.

The ratio of the heating weight reduction rate at 500 ℃ measured under the condition from 30 ℃ and at a temperature rise rate of 10 ℃/min to the heating weight reduction rate at 900 ℃ measured under the condition from 30 ℃ and at a temperature rise rate of 10 ℃/min was evaluated as the "ratio of the weight reduction rate to 500 ℃.

(Raman spectroscopy apparatus)

The measurement was carried out using a laser Raman microscope (Nanophoton corp. RAMATOuch VIS-NIR-DIS) at a laser wavelength of 532 nm. From RBM (100 cm) as a signal derived from the vibration of the carbon nanotube in the diameter direction^-1～300cm^-1Nearby) the diameter was calculated. Since carbon nanotubes having a diameter of more than 2.5nm cannot be detected by this method, the diameter is calculated by combining observation with a transmission electron microscope, which will be described later. The intensity ratio G/D of the G band and the D band representing the crystallinity of the carbon nanotube is represented by the G band (1590 cm)^-1Nearby) and D band (1300 cm)^-1Nearby) is calculated.

(Transmission electron microscope observation)

The observation was performed using a transmission electron microscope (transmission electron microscope HF-2000 with FEG manufactured by Hitachi High-Technologies Corporation) at an acceleration voltage of 200 kV. The observation sample was dispersed in an alcohol solvent, and the dispersion was fixed to a fine mesh by suction (Japanese text: ブロッティング) and vacuum-dried. The field of view was enlarged to 100 ten thousand times, and the diameter (average value), the ratio of single layer and multilayer (two or more layers) were determined from the observed 50 carbon nanotubes.

Evaluation of the dispersion medium (B) was performed as follows.

(shear viscosity)

The viscosity of the dispersion medium was measured using a rheometer (manufactured by Thermo Fisher Scientific Inc., trade name: HAAKE MARSIII). The temperature conditions were unified at 30 ℃ and the cone used was C60/2 °. The shear viscosity at a shear rate of 100[1/S ] was set as a representative value.

(dissolution parameters)

Calculated by using the calculation formula of Fedors.

SP value (δ) ([ Σ Ecoh/Σ V ]1/2

Σ Ecoh represents the energy of aggregation, Σ V represents the molar molecular volume, and is proposed as a constant for Fedors depending on the kind of substituent.

Evaluation of the resin (C) was performed as follows.

(all light transmittance)

The total light transmittance was measured according to JIS K7361-1. The light transmittance in the visible light region of the injection-molded article (thickness: 10mm) was measured using an ultraviolet-visible spectrophotometer (manufactured by JASCO Corporation, trade name: V-780). The higher the light transmittance, the more transparent.

The dispersion was evaluated as follows.

(Feret length distribution)

The Feret length distribution of the carbon nanotube particles in the carbon nanotube dispersion liquid in the range of 0.8 μm to 1000 μm was evaluated using an image analysis particle size distribution analyzer (manufactured by JASCO International Co., Ltd., trade name: CF-3000). In this method, images were taken with a 660-thousand-pixel camera while circulating the dispersion, and the particle size of particles in the range of 0.8 μm to 1mm was measured. 0.02mL of the dispersion was diluted with isopropyl alcohol so that the concentration of carbon nanotubes became 3X 10^-5The total amount of the solution was 150mL, and 0.1mL of the solution was measured. The observed particle number is about 4000 to 6000. The distribution of the particles to be observed is represented by a histogram in which the volume fraction is taken on the vertical axis. In the Ferrett length distribution, the proportion of the Ferrett length of 50 μm or more was evaluated.

(average Feret length)

The average Fireyt length can be calculated as the Fireyt length at 50% of the volume fraction cumulative value from 0.8 μm in the distribution measurement of the image analysis particle size distribution of 0.8 μm to 1000 μm, and determined by 3-fold averaging.

The molded article was evaluated as follows.

Volume resistance measurement

Under standard conditions (23 ℃ C., 50% RH), a 10mm × 2mm × 1mm sample piece was cut out in a strip direction from the center of the carbon nanotube/polycarbonate molded body toward the irradiation direction, silver paste was applied to both ends in the strip direction, and the volume resistance value was measured by a two-terminal method using a semiconductor parameter analyzer (manufactured by Keyship Technologies Inc.).

Determination of surface resistance value

Under standard conditions (23 ℃ C., 50% RH), the USR probe MCP-HTP14 was pressed against the surface of the carbon nanotube/polycarbonate molded body under a load of 1kg using a high resistivity meter Hiresta-UX MCP-HT800 (manufactured by Mitsubishi Chemical Analytical Co., Ltd.) and the surface resistance value was measured by a constant voltage application/leakage current measurement method.

Total light transmission

The total light transmittance was measured according to JIS K7361-1. The light transmittance in the visible light region of the injection-molded article (thickness: 1mm) was measured using an ultraviolet-visible spectrophotometer (product name: V-780, manufactured by JASCO Corporation). The higher the light transmittance, the more transparent.

The raw materials used in the examples and comparative examples are described below.

[ carbon nanotubes (A) ]

< carbon nanotube (A-1) >)

Diameter of 2.0nm

Single layer: multilayer 96: 4

The heating weight loss rate to 900 ℃ in thermogravimetric measurement was 99%

The weight loss rate to 500 ℃ is 15%

G/D ratio 142 in Raman spectroscopy

< carbon nanotube (A-2) >)

Diameter of 1.3nm

Single layer: multilayer 86: 14

The weight loss rate at 900 ℃ to 500 ℃ in thermogravimetric measurement is 83% to 8%

G/D ratio 50 in Raman spectroscopy

< carbon nanotube (A-3) >)

Diameter of 2.0nm

Single layer: multilayer 96: 4

The heating weight loss at 900 ℃ in the thermogravimetric measurement was 93%

The weight loss rate to 500 ℃ is 17%

G/D ratio 98 in Raman Spectroscopy

< carbon nanotube (A-4) >)

Diameter of 3.7nm

Single layer: multilayer 96: 4

The heating weight loss rate to 900 ℃ in thermogravimetric measurement was 99%

The weight loss rate to 500 ℃ is 3%

G/D ratio in Raman Spectroscopy 7.8

[ Dispersion Medium (B) ]

Diallyl phthalate

Shear viscosity: 12.3[ mPas ] (30 ℃ C., shear rate 100[1/S ])

Dissolution parameters: 10.5

[ resin (C) ]

Polycarbonate resin (product name "Panlite 1225Y")

Total light transmittance: 92 percent of

(preparation of Dispersion)

The dispersion was produced as follows.

(Dispersion 1)

A dispersion liquid 1 was prepared by dispersing carbon nanotubes (A-1) and diallyl phthalate in Nanovater L-ES (Yoshida KIKAI CO., LTD., manufactured by Ltd.) so that the concentration of carbon nanotubes (A-1) became 0.2 mass%. The Ferrett length distribution is shown in FIG. 1. The proportion of the Ferrett length of 50 μm or more in the Ferrett length distribution is 1%, and the average Ferrett length is 42 μm.

(Dispersion 2 to 4)

Dispersions 2 to 4 were produced in the same manner as in dispersion 1 except that carbon nanotube (a-1) was used as dispersion 2, carbon nanotube (a-2) was used as dispersion 3, and carbon nanotube (a-4) was used as dispersion 4, instead of carbon nanotube (a-1). FIG. 1 shows the Ferrett length distribution, the average Ferrett length, and the ratio of the Ferrett length to 50 μm or more.

(production of composition and molded article containing carbon nanotubes)

The composition and molded body containing carbon nanotubes were produced as follows.

Each raw material was charged into a hopper of a twin-screw extruder (model "TEM-18 SS", manufactured by Toshiba mechanical Co., Ltd.) with a vent at the formulation shown in Table 1 to obtain a composition containing carbon nanotubes.

Using an injection molding machine (model No. FNX80III-9A ", manufactured by Hitachi resin industries, Ltd.), each test piece was molded from the carbon nanotube-containing composition at a cylinder temperature of 280 ℃ and a mold temperature of 110 ℃, and the volume resistance value, the surface resistance value, and the total light transmittance were measured. The results are shown in Table 1.

[ Table 1]

The respective amounts of the dispersion liquid 1 to 4 and the polycarbonate resin are in parts by mass.

Table 1 shows that: the molded bodies of examples 1 and 2 using the dispersion of the present invention not only maintained high transparency but also had low surface resistance values, wherein the molded body of example 1 had a low volume resistance value and a lower surface resistance value.

Industrial applicability of the invention

The molded article of the carbon nanotube-containing composition containing the dispersion and the resin of the present invention has high transparency and low surface resistance value, and is useful in various fields such as electric devices, machine parts, and automobile parts.