JP2021080121A - Manufacturing method of semiconductor type single layer carbon nanotube dispersion - Google Patents

Abstract

To provide a manufacturing method of a semiconductor type SWCNT dispersion capable of performing separation of a semiconductor type SWCNT from a SWCNT mixture containing a semiconductor type SWCNT and a metallic SWCNT, in an aqueous medium, by use and simple operation of a readily available separating agent.SOLUTION: A manufacturing method of a semiconductor type single layer carbon nanotube dispersion comprising: a step A of preparing SWCNT dispersion to be separated containing a SWCNT mixture, an aqueous medium, a polymer containing a constituent unit A derived from a monomer expressed by the following formula (1) and an iron inclusion having reducibility, and ; a step B of sampling a supernatant containing the semiconductor type SWCNT from centrifugally separated SWCNT dispersion to be separated after centrifugal separation of the SWCNT dispersion to be separated, in which a weight average molecular weight of the polymer is 1,000 or larger and 100,000 or smaller. CH2=CH-COOM (1) [in the formula (1), M expresses a hydrogen atom, a metal atom, or a group having a structure expressed by the following formula (2).].SELECTED DRAWING: None

Description

The present disclosure describes a method for producing a semiconductor-type single-walled carbon nanotube dispersion liquid, a method for producing a semiconductor-type single-walled carbon nanotube including the manufacturing method as a step, and separation of a metal-type single-walled carbon nanotube and a semiconductor-type single-walled carbon nanotube. Regarding the method.

In recent years, nanometer-sized carbon materials are expected to be applied to various fields due to their physical and chemical properties. One such material is carbon nanotube (hereinafter, may be referred to as “CNT”). The CNT has a structure in which a graphene sheet is rolled into a cylindrical shape, and a CNT having only one layer of a cylinder is called a single-walled carbon nanotube (sometimes referred to as "SWCNT" below). It has been.

It is known that CNTs have different electrical characteristics depending on how the graphene sheet is wound, the diameter, and the like. In particular, since SWCNTs are greatly affected by the quantum effect, there are those showing metallic properties (metal-type CNTs) and those showing semiconducting properties (semiconductor-type CNTs). Known methods for producing SWCNTs include a high-pressure carbon monoxide disproportionation method (HiPco method), an improved direct injection pyrolysis synthesis method (e-DIPS method), an arc discharge method, and a laser ablation method. However, at present, the technology for producing only one of the types of CNTs has not been established, and when applying SWCNTs to various applications, it is possible to separate the desired type of SWCNTs from the mixture. Needed. Metal-type CNTs are expected to be used for touch panels, transparent electrodes for solar cells, fine wiring of devices, etc. by utilizing their excellent conductivity, and semiconductor-type CNTs are applied to transistors, sensors, etc. Is expected.

Several methods for separating the metal type SWCNT and the semiconductor type SWCNT have already been reported. For example, a density gradient centrifugation method (Patent Document 1) in which SWCNTs are dispersed using a surfactant such as sodium dodecyl sulfate or sodium cholate, mixed with a density gradient agent and centrifuged, and SWCNTs using a surfactant. An electric field separation method (Patent Document 2) in which an electric field is applied to a dispersion liquid in which the mixture is dispersed, and a method in which a complex of a semiconductor-type SWCNT and a separating agent is formed and taken out by mixing with a separating agent such as porphyrin in an organic solvent (Patent Document 2). Patent Document 3), a method of mixing with a separating agent such as a polythiophene derivative in an organic solvent and selectively separating the semiconductor type SWCNT by utilizing the interaction between the semiconductor type SWCNT and the separating agent (Patent Document 4). A method of separating a semiconductor SWCNT by mixing it with a separating agent such as a flavin derivative in an organic solvent and utilizing the adsorption action of the separating agent on the semiconductor SWCNT (Patent Document 5), SWCNT using a surfactant. A method is known in which the dispersed dispersion is placed in a separation container filled with a separation material such as agar gel, and the semiconductor-type SWCNT adsorbed on the separation material is eluted from the separation material using an eluent (Patent Document 6). ..

Japanese Unexamined Patent Publication No. 2010-1162 Japanese Unexamined Patent Publication No. 2008-55375 Special Table 2007-591594 Japanese Patent Application Laid-Open No. 2014-503445 WO2014 / 136981 Japanese Unexamined Patent Publication No. 2012-36041

However, the separation method disclosed in Patent Documents 1 and 6 requires a density gradient agent, an agar gel, or the like, and requires many operation steps. The separation method disclosed in Patent Document 2 requires an electrophoresis device, takes time for separation, and has a low concentration of SWCNTs to be separated. The separation methods disclosed in Patent Documents 3, 4 and 5 are not practical in that they need to be carried out in a non-polar solvent and that an expensive separating agent is required.

In the present disclosure, a semiconductor-type SWCNT dispersion can be separated from a SWCNT mixture containing a semiconductor-type SWCNT and a metal-type SWCNT in an aqueous medium by using an easily available separating agent and a simple operation. The present invention relates to a method for producing a semiconductor-type SWCNT, a method for producing a semiconductor-type SWCNT, a method for separating a semiconductor-type SWCNT and a metal-type SWCNT, and a method for producing a semiconductor-type SWCNT-containing ink.

式（２）中、Ｒ¹、Ｒ²、Ｒ³、Ｒ⁴はそれぞれ独立に、水素原子、又は水酸基を有していてもよい炭素数が１以上２以下のアルキル基を示す。 In one embodiment, the present disclosure comprises a SWCNT mixture containing a semiconductor type SWCNT and a metal type SWCNT, an aqueous medium, and a polymer containing a structural unit A derived from a monomer represented by the following formula (1). From the step A of preparing the SWCNT dispersion to be separated containing the iron-containing substance having reducibility and the SWCNT dispersion to be separated after centrifuging the SWCNT dispersion, the semiconductor type The present invention relates to a method for producing a semiconductor-type single-walled carbon nanotube dispersion, which comprises a step B of collecting a supernatant containing SWCNTs and having a weight average molecular weight of 1,000 or more and 100,000 or less of the polymer.
CH ₂ = CH-COMM (1)
In the formula (1), M represents a hydrogen atom, a metal atom, or a group having a structure represented by the following formula (2).

In formula (2), R ¹ , R ² , R ³ , and R ⁴ each independently represent an alkyl group having 1 or more and 2 or less carbon atoms which may have a hydrogen atom or a hydroxyl group.

The present disclosure relates to a method for producing a semiconductor-type SWCNT, which comprises, in one aspect, a step of filtering the semiconductor-type SWCNT dispersion obtained by the method for producing the semiconductor-type SWCNT dispersion of the present disclosure and collecting the semiconductor-type SWCNT. ..

In one aspect, the present disclosure includes a step of drying the semiconductor-type SWCNT dispersion obtained by the method for producing the semiconductor-type SWCNT dispersion of the present disclosure to obtain a mixture containing the semiconductor-type single-layer SWCNT and the polymer. The present invention relates to a method for producing a semiconductor type SWCNT, which comprises a step of removing the polymer from the mixture and collecting a semiconductor type SWCNT.

式（２）中、Ｒ¹、Ｒ²、Ｒ³、Ｒ⁴はそれぞれ独立に、水素原子、又は水酸基を有していてもよい炭素数が１以上２以下のアルキル基を示す。 In one embodiment, the present disclosure comprises a SWCNT mixture containing a semiconductor type SWCNT and a metal type SWCNT, an aqueous medium, and a polymer containing a structural unit A derived from a monomer represented by the following formula (1). The semiconductor type is obtained from the step A of preparing the SWCNT dispersion to be separated containing the iron-containing substance having a reducing property, and the SWCNT dispersion to be separated which is centrifuged after the SWCNT dispersion to be separated. The present invention relates to a method for separating a semiconductor type SWCNT and a metal type SWCNT, which comprises a step B of collecting a supernatant containing SWCNT and has a weight average molecular weight of 1,000 or more and 100,000 or less of the polymer.
CH ₂ = CH-COMM (1)
In the formula (1), M represents a hydrogen atom, a metal atom, or a group having a structure represented by the following formula (2).

In formula (2), R ¹ , R ² , R ³ , and R ⁴ each independently represent an alkyl group having 1 or more and 2 or less carbon atoms which may have a hydrogen atom or a hydroxyl group.

In one aspect, the present disclosure relates to a method for producing a semiconductor-type SWCNT dispersion liquid of the present disclosure or a method for producing a semiconductor-type SWCNT-containing ink including the method for producing the semiconductor-type SWCNT of the present disclosure as one step.

According to the present disclosure, a method for producing a semiconductor-type SWCNT dispersion, which can be carried out in an aqueous medium by using an easily available separating agent and a simple operation, and which is excellent in separability and dispersibility of the semiconductor-type SWCNT, and its production. It is possible to provide a method for producing a semiconductor type SWCNT including a method as a step, a method for separating a semiconductor type SWCNT and a metal type SWCNT, and a method for producing a semiconductor type SWCNT-containing ink.

In the present disclosure, since the SWCNT dispersion liquid to be separated contains a specific polymer and an iron-containing substance having a reducing property, it is easy to obtain the separation of the metal type SWCNT and the semiconductor type SWCNT in the SWCNT dispersion liquid to be separated. It is based on the knowledge that it can be done by using a simple separating agent and by simple operation.

The details of the mechanism of effect manifestation of the present disclosure are not clear, but it is inferred as follows.
In the present disclosure, the SWCNT dispersion to be separated contains a polymer containing a structural unit A derived from the monomer represented by the above formula (1) and an iron-containing material having a reducing property, and the weight thereof. Since the weight average molecular weight of the coalescence is a value within a specific range, the semiconductor type SWCNTs are selectively dispersed in the dispersion liquid, while the metal type SWCNTs aggregate, so that this is the target of centrifugation. Therefore, it is presumed that good separation between the metal type SWCNT and the semiconductor type SWCNT is possible. Further, it is considered that the reducing iron-containing material suppresses the oxidation of SWCNTs in the dispersion liquid, and the separability and dispersibility of the semiconductor type SWCNTs are improved.
However, this disclosure is not construed as limiting to these mechanisms.

式（２）中、Ｒ¹、Ｒ²、Ｒ³、Ｒ⁴は、それぞれ独立に、水素原子、又は水酸基を有していてもよい炭素数が１以上２以下のアルキル基を示す。 [Manufacturing method of semiconductor type SWCNT dispersion liquid, method of separating semiconductor type SWCNT and metal type SWCNT]
In one aspect, the present disclosure relates to a method for producing a semiconductor-type SWCNT dispersion liquid (hereinafter, also referred to as “method for producing a dispersion liquid of the present disclosure”), which comprises the following steps A and B. Further, the present disclosure relates to a method for separating a semiconductor type SWCNT and a metal type SWCNT (hereinafter, also referred to as “the separation method of the present disclosure”), which includes the following steps A and B in another aspect.
(Step A) A single-walled carbon nanotube containing a semiconductor-type SWCNT and a metal-type SWCNT (hereinafter, also referred to as “SWCNT mixture”) and a monomer represented by the following formula (1) (hereinafter, also referred to as “monomer A”). A SWCNT dispersion to be separated is prepared, which comprises a polymer containing a structural unit A derived from (referred to as), a reducing iron-containing material, and an aqueous medium.
(Step B) After centrifuging the SWCNT dispersion liquid to be separated, a supernatant liquid containing the semiconductor type SWCNT is collected from the centrifugally separated SWCNT dispersion liquid to be separated.
CH ₂ = CH-COMM (1)
In the formula (1), M represents a hydrogen atom, a metal atom, or a group having a structure represented by the following formula (2).

In the formula (2), R ¹ , R ² , R ³ , and R ⁴ each independently represent an alkyl group having 1 or more and 2 or less carbon atoms which may have a hydrogen atom or a hydroxyl group.

In the present disclosure, "collecting the supernatant liquid containing the semiconductor type SWCNT" means the semiconductor type SWCNT with respect to the ratio of the semiconductor type SWCNT to the metal type SWCNT in the liquid to be separated SWCNT obtained in step A. This means that the supernatant liquid having an improved ratio of the above is collected, and the supernatant liquid is a semiconductor type SWCNT dispersion liquid. In the present disclosure, it is not excluded that the supernatant liquid contains a relatively small amount of the metal type SWCNT as compared with the semiconductor type SWCNT. When the separability of the semiconductor type SWCNT is improved, the ratio of the semiconductor type SWCNT in the SWCNT in the supernatant liquid increases, and it becomes more useful as a material for a semiconductor device.

In step B, the supernatant liquid can be collected, for example, by separating the supernatant liquid and its residue. The residue contains a precipitate containing a relatively large amount of metal-type SWCNTs as compared with semiconductor-type SWCNTs.

[Step A]
The SWCNT dispersion liquid to be separated in the step A in the method for producing the dispersion liquid of the present disclosure and the separation method of the present disclosure has, in one or more embodiments, a weight containing at least a structural unit A derived from the monomer A. After preparing a mixture containing the coalescence, the SWCNT mixture, a reducing iron-containing substance, and an aqueous medium (hereinafter, may be abbreviated as "mixture A"), the mixture A is dispersed. It can be obtained by processing. The mixture A can be prepared, for example, by adding the SWCNT mixture and an iron-containing substance having a reducing property to the aqueous solution of the polymer simultaneously or separately. The reducing iron-containing material may not be contained in the mixed solution A, and may be added after the mixed solution containing the polymer, the SWCNT mixture and the aqueous medium is dispersed and treated.

[Polymer containing structural unit A]
The structural unit A is a structural unit derived from the monomer A represented by the above formula (1).
In the above formula (1), M is a hydrogen atom, a metal atom, or a salt with ammonium represented by the above formula (2) from the viewpoint of improving the separability and dispersibility of the semiconductor type SWCNT. From the viewpoint of improving the separability, dispersibility, and versatility of the semiconductor type SWCNT, it is preferably a hydrogen atom or a salt with ammonium represented by the above formula (2), and more preferably a hydrogen atom. ..

The content of the structural unit A in all the structural units of the polymer is preferably 50 mol% or more, more preferably 80 mol% or more, still more preferably 90 mol, from the viewpoint of improving the separability and dispersibility of the semiconductor type SWCNT. % Or more, and even more preferably 95 mol% or more.

The polymer may contain a structural unit B derived from a monomer B other than the monomer A from the viewpoint of improving the separability and dispersibility of the semiconductor type SWCNT. Monomer B represents one kind or two or more kinds of monomers other than monomer A. The monomer B may be appropriately selected depending on conditions such as centrifugation. For example, it is preferable that the monomer B improves the affinity of the polymer for the semiconductor type SWCNT and the metal type SWCNT, and is hydrophobic. A monomer containing a portion exhibiting sex is more preferable.

Specifically, the monomer B is a hydrophilic monomer such as a dibasic acid monomer such as maleic acid or itaconic acid and a salt thereof, methoxypolyoxyethylene (meth) acrylate, polyoxyethylene vinyl ether or the like. Examples thereof include monomers containing a polyoxyethylene chain in the molecule, nonionic monomers such as hydroxyethyl (meth) acrylate and acrylamide. As the hydrophobic monomer, an alkyl group (cyclic structure) having 1 or more and 24 or less carbon atoms such as methyl (meth) acrylate, benzyl (meth) acrylate, methoxypolyoxypropylene (meth) acrylate, or diisobutylene may be contained. ), Examples thereof include styrene and the like. Examples of the amphipathic monomer include monomers having a hydrophobic part and a hydrophilic part in the molecule such as phenoxypolyoxyethylene (meth) acrylate and polyoxypropylene polyoxyethylene (meth) acrylate.

The weight average molecular weight of the polymer is 1,000 or more, preferably 1,500 or more, more preferably 2,000 or more, and the same, from the viewpoint of improving the separability and dispersibility of the semiconductor type SWCNT. From the viewpoint of 100,000 or less, preferably 50,000 or less, more preferably 30,000 or less, and further preferably 10,000 or less. In the present disclosure, the weight average molecular weight of the polymer is based on a gel permeation chromatography method (polyethylene glycol equivalent), and can be specifically measured by the method described in Examples.

The content of the polymer in the mixed liquid A and in the SWCNT dispersion liquid to be separated is preferably 0.01% by mass or more, more preferably 0.1% by mass, from the viewpoint of improving the separability of the semiconductor type SWCNT. % Or more, more preferably 0.5% by mass or more, still more preferably 1% by mass or more, and from the viewpoint of improving the dispersibility of the semiconductor type SWCNT, preferably 10% by mass or less, more preferably 5% by mass. Below, it is more preferably 3% by mass or less, and even more preferably 2.5% by mass or less.

[SWCNT]
The SWCNT used for preparing the mixed liquid A and the SWCNT dispersion liquid to be separated is not particularly limited. The SWCNT is synthesized by a conventionally known synthetic method such as the HiPco method or the e-DIPS method, and may include those having various winding methods and diameters. The metal SWCNT and the semiconductor SWCNT may be contained in an arbitrary ratio, but the SWCNT generally synthesized is a SWCNT mixture containing about 1/3 of the metal SWCNT and about 2/3 of the semiconductor SWCNT. is there.

The average diameter of the SWCNT is preferably 0.5 nm or more, more preferably 0.8 nm or more from the viewpoint of improving the separability of the semiconductor type SWCNT, and from the same viewpoint, preferably 3 nm or less, more preferably 2 nm. It is as follows. The average diameter of SWCNTs can be calculated by measuring and averaging the diameters of 10 or more CNTs from an image obtained using a transmission electron microscope.

From the viewpoint of electrical characteristics, the average length of the SWCNT is preferably 0.1 μm or more, more preferably 0.3 μm or more, still more preferably 0.5 μm or more, and the separability and dispersibility of the semiconductor type SWCNT are improved. From the viewpoint of improvement, it is preferably 100 μm or less, more preferably 50 μm or less, still more preferably 20 μm or less, still more preferably 10 μm or less. The average length of SWCNTs can be calculated, for example, by measuring and averaging the lengths of 10 or more CNTs from an image obtained using a transmission electron microscope.

The content of SWCNT in the mixed solution A and in the SWCNT dispersion to be separated is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, from the viewpoint of improving the separability of the semiconductor type SWCNT. It is more preferably 0.03% by mass or more, and from the viewpoint of improving the separability and dispersibility of the semiconductor type SWCNT, it is preferably 5% by mass or less, more preferably 1% by mass or less, still more preferably 0. It is 5% by mass or less.

[Reducing iron-containing material]
In the present disclosure, the "reducing iron-containing material" refers to an iron-containing material containing zero-valent or divalent iron in one or more embodiments. The reducing iron-containing material may be one kind or a combination of two or more kinds.
In the present disclosure, the "iron-containing material" may include elemental iron, iron alloys, or iron compounds.

Examples of the reducing iron-containing material include an iron-containing material containing at least one of a zero-valent iron and a divalent iron compound from the viewpoint of improving the separability and dispersibility of the semiconductor-type SWCNT. At least one selected from valent iron and divalent iron compounds is preferred.
As the zero-valent iron, particulate iron (zero-valent) is preferable from the viewpoint of improving the separability and dispersibility of the semiconductor type SWCNT, and the particulate iron (zero-valent) is reduced iron powder or atomized iron. Examples include powder.
_{Examples of the divalent iron compound include FeCl 2} , FeBr ₂ , FeI ₂ , FeSO ₄ , Fe (OH) ₂ , FeO, and the like from the viewpoint of improving the separability and dispersibility of the semiconductor type SWCNT. From the viewpoint of economy, FeCl ₂ is preferable.
Since the trivalent iron compound generally does not have reducing property, it can be said that the trivalent iron compound is not included in the reducing iron compound in the present disclosure in one embodiment. ..
Further, the same effect can be obtained even when the reducing iron-containing material is previously contained in the mixed solution A, the SWCNT used for preparing the SWCNT dispersion to be separated, and the polymer. In particular, the same effect can be obtained when iron is contained in the metal catalyst used in producing SWCNT. Therefore, the content of the reducing iron-containing material also includes the reducing iron-containing material previously contained in SWCNT and the polymer.

The content (mass ppm) of the reducing iron-containing material in the mixed liquid A and the SWCNT dispersion liquid to be separated is in terms of Fe atoms, from the viewpoint of improving the separability and dispersibility of the semiconductor type SWCNT. It is preferably 15 mass ppm or more, more preferably 25 mass ppm or more, further preferably 45 mass ppm or more, and from the viewpoint of improving the dispersibility of the semiconductor type SWCNT, preferably 1000 mass ppm or less, more preferably 600 mass ppm or more. It is ppm or less, more preferably 300 mass ppm or less, and even more preferably 150 mass ppm or less.

The content (mmol / L) of the reducing iron-containing material in the mixed solution A and the SWCNT dispersion to be separated is in terms of Fe atoms from the viewpoint of improving the separability and dispersibility of the semiconductor type SWCNT. 0.25 mmol / L or more, more preferably 0.45 mmol / L or more, still more preferably 0.80 mmol / L or more, and from the viewpoint of improving the dispersibility of the semiconductor type SWCNT, preferably 18 mmol / L or more. Hereinafter, it is more preferably 10 mmol / L or less, still more preferably 5 mmol / L or less, and even more preferably 3 mmol / L or less.

Here, the content of reducing iron (Fe ²⁺ ) in the aqueous solution can be measured by JIS K0400-57-10 (ISO 6332).
When trivalent iron (Fe ³⁺ ) coexists, reduction in aqueous solution is performed by subtracting the ^{Fe 3+} content from the iron content measured by the measurement method using JIS K0400-57-10 (ISO 6332). The content of iron (Fe ²⁺ ) having a property can be determined. The content of Fe ^{3+ in} the aqueous solution can be measured by the following method.
<Fe ³⁺ content>
Quantify using a high performance liquid chromatograph transition metal analysis system (manufactured by Shimadzu Corporation). Transition metal ions are eluted by cation exchange chromatography, and post-column absorption detection using 4- (2'-pyridylazo) -resorcinol (PAR) as a color-developing reagent is performed.

The mass ratio (reducing iron-containing material / SWCNT) of the content (Fe atom equivalent) of the iron-containing material having reducibility to the content of SWCNT in the mixed liquid A and the SWCNT dispersion liquid to be separated is From the viewpoint of improving the separability and dispersibility of the semiconductor type SWCNT, it is preferably 0.04 or more, more preferably 0.07 or more, still more preferably 0.10 or more, still more preferably 0.13 or more. From the viewpoint of improving the dispersibility of the semiconductor type SWCNT, it is preferably 3 or less, more preferably 1.7 or less, still more preferably 1.0 or less, still more preferably 0.6 or less, still more preferably 0.5. It is as follows.

[Aqueous medium]
The mixed liquid A and the SWCNT dispersion liquid to be separated contain an aqueous medium as a dispersion medium. Water is preferable as the aqueous medium, and pure water, ion-exchanged water, purified water or distilled water is preferable, and pure water is more preferable, from the viewpoint of improving the separability and dispersibility of the semiconductor type SWCNT.

The mixed solution A and the SWCNT dispersion to be separated may contain lower alcohols such as methanol, ethanol and isopropyl alcohol and water-soluble organic solvents such as acetone, tetrahydrofuran and dimethylformamide as an aqueous medium in addition to water. Good.

When the aqueous medium is a combination of water and a dispersion medium other than water, the proportion of water in the dispersion medium is preferably 70% by mass or more, more preferably from the viewpoint of improving the separability and dispersibility of the semiconductor type SWCNT. Is 80% by mass or more, more preferably 90% by mass or more.

The content of the aqueous medium in the mixed solution A and in the SWCNT dispersion to be separated is preferably 85% by mass or more, more preferably 90, from the viewpoint of improving the separability and productivity of the semiconductor type SWCNT. By mass% or more, more preferably 93% by mass or more, and from the same viewpoint, preferably 99.9% by mass or less, more preferably 99.8% by mass or less, still more preferably 99.5% by mass or less. Even more preferably, it is 99.0% by mass or less.

The pH of the mixed liquid A and the SWCNT dispersion liquid to be separated is preferably 1 or more, more preferably 1.5 or more, still more preferably 2 or more, from the viewpoint of improving the separability and dispersibility of the semiconductor type SWCNT. And, from the same viewpoint, it is preferably 5 or less, more preferably 4 or less, still more preferably 3.5 or less. In the present disclosure, the pH of the mixed liquid A and the SWCNT dispersion liquid to be separated is a value at 25 ° C., and can be measured using, for example, a pH meter (manufactured by DKK-TOA CORPORATION).

The dispersion treatment for the mixture A can be performed using, for example, a disperser such as a bath type ultrasonic disperser, a homomixer, a high-pressure homogenizer, an ultrasonic homogenizer, a jet mill, a bead mill, or a miller.

In the step A, the mixed liquid A may be defoamed before the dispersion treatment.

[Step B]
In step B, the SWCNT dispersion liquid to be separated obtained in step A is targeted for centrifugation, and the supernatant liquid containing the semiconductor type SWCNT in the centrifugally separated SWCNT dispersion liquid to be separated is collected. In the supernatant, the ratio of the semiconductor type SWCNT is improved with respect to the ratio of the semiconductor type SWCNT and the metal type SWCNT in the SWCNT dispersion liquid to be separated before being subjected to centrifugation. The ratio varies depending on the centrifugation conditions and the like, but the rotation speed of the centrifuge is preferably 5,000 rpm or more, more preferably 10,000 rpm or more, from the viewpoint of improving the separability and dispersibility of the semiconductor type SWCNT. From the same viewpoint, it is preferably 100,000 rpm or less, more preferably 70,000 rpm or less. The gravitational acceleration of the centrifuge is preferably 10 kG or more, more preferably 50 kG or more from the viewpoint of improving the separability and dispersibility of the semiconductor type SWCNT, and preferably 1000 kG or less, more preferably 500 kG from the same viewpoint. It is as follows.

The method for producing the semiconductor-type SWCNT dispersion liquid of the present disclosure and the method for separating the semiconductor-type SWCNT and the metal-type SWCNT of the present disclosure are the supernatant collected after the step B from the viewpoint of improving the storage stability of the semiconductor-type SWCNT dispersion liquid. It is preferable to include step C of adding a reducing agent to the liquid.
Since the supernatant obtained in step B contains a reducing iron-containing substance, if it is left for a long time, the reducing iron-containing substance is oxidized and changed to trivalent iron ions, which is poly. The stability of the semiconductor-type SWCNT dispersion may be impaired, such as inhibiting the dispersibility of the semiconductor-type SWCNT dispersed with a polymer such as acrylic acid or causing precipitation of iron (III) hydroxide. Therefore, in step C, it is considered that the pH of the supernatant can be adjusted to, for example, 2 to 3 by adding a reducing agent to the supernatant obtained in step B, and the formation of trivalent iron ions can be suppressed. ..

From the viewpoint of improving the storage stability of the semiconductor-type SWCNT dispersion, the addition of the reducing agent is preferably within 48 hours, more preferably within 24 hours, still more preferably within 12 hours, and even more preferably within 48 hours after the completion of step B. Within 3 hours, even more preferably within 1 hour, even more preferably within 10 minutes, even more preferably immediately after the end of step B.

Examples of the reducing agent include at least one selected from ascorbic acid, ascorbic acid derivatives, tocopherols, and formaldehyde. Among these, ascorbic acid is preferable from the viewpoint of availability, safety and stability. The reducing agent may be one kind or a combination of two or more kinds.

The content (mass ppm) of the reducing agent in the supernatant to which the reducing agent is added is preferably 10 mass ppm or more, more preferably 100 mass ppm or more, from the viewpoint of improving the storage stability of the semiconductor type SWCNT dispersion liquid. It is more preferably 500 mass ppm or more, and from the viewpoint of improving the storage stability of the semiconductor type SWCNT dispersion and from the viewpoint of economic efficiency, it is preferably 30,000 mass ppm or less, more preferably 10,000 mass ppm or less, still more preferably. It is 2000 mass ppm or less, and even more preferably 1000 mass ppm or less. When the reducing agent is a combination of two or more kinds, the content of the reducing agent means the total content thereof.

The content (mmol / L) of the reducing agent in the supernatant to which the reducing agent is added is preferably 0.05 mmol / L or more, more preferably 0, from the viewpoint of improving the storage stability of the semiconductor type SWCNT dispersion liquid. It is .5 mmol / L or more, more preferably 3 mmol / L or more, and preferably 170 mmol / L or less, more preferably 60 mmol / L from the viewpoint of improving the storage stability of the semiconductor type SWCNT dispersion and from the viewpoint of economic efficiency. Below, it is more preferably 7 mmol / L or less.

The molar ratio of the reducing agent to the reducing iron-containing material in the supernatant to which the reducing agent is added (reducing agent / reducing iron-containing material (Fe atom equivalent)) is the storage of the semiconductor-type SWCNT dispersion. From the viewpoint of improving stability, it is preferably 0.1 or more, more preferably 0.5 or more, still more preferably 1 or more, and from the viewpoint of improving the storage stability of the semiconductor type SWCNT dispersion and from the viewpoint of economic efficiency. It is preferably 100 or less, more preferably 20 or less, still more preferably 10 or less, and even more preferably 5 or less.

In step C, as a method of adding the reducing agent, for example, a method of adding an aqueous solution of the reducing agent at a temperature of 25 ° C. and 0.5 to 1.5 mol / L to the supernatant can be mentioned.

[Manufacturing method of semiconductor type SWCNT and semiconductor type SWCNT]
A semiconductor type SWCNT can be produced by collecting the semiconductor type SWCNT from the semiconductor type SWCNT dispersion produced by the method for producing the semiconductor type SWCNT dispersion liquid of the present disclosure. The semiconductor type SWCNT can be collected from the semiconductor type SWCNT dispersion liquid, for example, by filtering the semiconductor type SWCNT from the semiconductor type SWCNT dispersion liquid with a membrane filter and then drying the semiconductor type SWCNT. When the semiconductor type SWCNT is filtered from the semiconductor type SWCNT dispersion liquid, the semiconductor type SWCNT in the semiconductor type SWCNT dispersion liquid may be subjected to pretreatment such as reprecipitation and then filtered. Alternatively, it can be carried out by drying the semiconductor-type SWCNT dispersion liquid and removing the coexisting polymer by means such as washing or thermal decomposition. Therefore, in one aspect, the present disclosure includes the step of filtering the semiconductor-type SWCNT dispersion obtained by the method for producing the semiconductor-type SWCNT dispersion of the present disclosure and collecting the semiconductor-type SWCNT. The present invention relates to a method (hereinafter, also referred to as “method A for manufacturing the semiconductor type SWCNT of the present disclosure”). Further, in another aspect of the present disclosure, the semiconductor-type SWCNT dispersion obtained by the method for producing the semiconductor-type SWCNT dispersion of the present disclosure is dried to obtain a mixture containing the semiconductor-type single-walled carbon nanotubes and the polymer. A method for producing semiconductor-type SWCNTs, which comprises a step of obtaining the mixture and a step of removing the polymer from the mixture to collect semiconductor-type single-walled carbon nanotubes (hereinafter, also referred to as "method B for producing semiconductor-type SWCNTs of the present disclosure"). Regarding. Further, the present disclosure relates to the semiconductor type SWCNT obtained by the manufacturing method A or B of the semiconductor type SWCNT of the present disclosure (hereinafter, also referred to as “semiconductor type SWCNT of the present disclosure”) in another aspect.

[Manufacturing method of semiconductor-type SWCNT-containing ink]
The present disclosure, in one aspect, includes a method for producing a semiconductor-type SWCNT dispersion liquid of the present disclosure or a method for producing a semiconductor-type SWCNT of the present disclosure as one step, and a method for producing a semiconductor-type SWCNT-containing ink (hereinafter, "" Also referred to as "a method for producing a semiconductor-type SWCNT-containing ink" of the present disclosure). One embodiment of the method for producing a semiconductor-type SWCNT-containing ink of the present disclosure includes, for example, the method A or B for producing a semiconductor-type SWCNT of the present disclosure as one step, and further comprises the semiconductor-type SWCNT, an organic solvent, and water. It includes a step of mixing at least one of them and, if necessary, at least one of a surfactant and a resin. Further, another embodiment of the method for producing a semiconductor-type SWCNT-containing ink of the present disclosure includes, for example, the method for producing a semiconductor-type SWCNT dispersion liquid of the present disclosure as one step, and the semiconductor-type SWCNT dispersion liquid and, if necessary, the above-mentioned semiconductor-type SWCNT dispersion liquid. The step of mixing the organic solvent, the surfactant and the resin which can be mixed with the dispersion liquid is included.

Examples of the organic solvent include aliphatic solvents such as n-hexane, n-octane, and n-decane: alicyclic solvents such as cyclohexane: aromatic solvents such as benzene and toluene, methanol, ethanol and the like. Examples thereof include alcohol solvents, glycol ether solvents such as diethylene glycol monomethyl ether, propylene glycol mono.methyl ether acetate, and butyl cellosolve. From the viewpoint of improving the film-forming property, the semiconductor-type SWCNT-containing ink of the present disclosure may further contain, for example, a polystyrene resin, an acrylic resin, a vinyl resin, or the like as the resin that can be dissolved or dispersed in a solvent. It may contain a known surfactant or other additive as a dispersant. The content of the semiconductor-type SWCNT in the semiconductor-type SWCNT-containing ink of the present disclosure may be appropriately set according to the intended use.

[Semiconductor type SWCNT-containing ink]
In one embodiment, the present disclosure comprises a polymer containing a semiconductor type single layer SWCNT, at least one of an organic solvent and water, and a structural unit A derived from the monomer represented by the formula (1). The present invention relates to a semiconductor-type SWCNT-containing ink (hereinafter, also referred to as “semiconductor-type SWCNT-containing ink” of the present disclosure), which comprises an iron-containing substance having a reducing property and at least one selected from the reducing agents.
One embodiment of the semiconductor-type SWCNT-containing ink of the present disclosure is selected from at least the semiconductor-type SWCNT of the present disclosure, at least one of an organic solvent and water, an iron-containing substance having the reducing property, and the reducing agent. It contains one type and, if necessary, a surfactant and a resin.

[Manufacturing method of semiconductor device]
In one aspect, the present disclosure comprises a step of printing or applying a semiconductor-type SWCNT-containing ink obtained by the method for producing a semiconductor-type SWCNT-containing ink of the present disclosure on a substrate to form a semiconductor layer. Regarding the manufacturing method.

Further, in another aspect, the present disclosure is a method for manufacturing a semiconductor element including a substrate and a gate electrode, a source electrode and a drain electrode arranged on the substrate, and the semiconductor type SWCNT-containing ink is printed. Alternatively, the present invention relates to a method for manufacturing a semiconductor device, which includes a step of forming a semiconductor circuit or a semiconductor film (semiconductor layer) by coating. Examples of the printing method of the semiconductor type SWCNT-containing ink include inkjet printing, screen printing, offset printing, letterpress printing and the like. A step of forming a circuit by performing etching or the like after forming a semiconductor film by printing or coating may be included.

Hereinafter, the present disclosure will be described in more detail by way of examples, but these are exemplary and the present disclosure is not limited to these examples.

1. Ingredients used to prepare the SWCNT dispersion to be separated The following components were used to prepare the SWCNT dispersion to be separated.
(SWCNT mixture)
SWCNT1: "APJ" made by Meijo Nanocarbon Co., Ltd. (average diameter 1.4 nm, average length 1-5 μm, iron: below the detection limit)
SWCNT2: "SO" Meijo Nanocarbon Co., Ltd. APJ refined product (average diameter 1.4 nm, average length 1-5 μm, iron: below the detection limit)
(Polymer)
Polyacrylic acid: manufactured by Alldrich (weight average molecular weight 2000)
(Metal compound)
FeCl ₂ (Fe ²⁺ ): Fujifilm Wako Pure Chemical Industries, Ltd. FeCl ₃ (Fe ³⁺ ): Fujifilm Wako Pure Chemical Industries, Ltd. CoCl ₂ (Co ²⁺ ): Fujifilm Wako Pure Chemical Industries, Ltd. NiCl ₂ (Ni ²⁺ ) manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. (reducing agent)
Ascorbic acid: manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. (aqueous solvent)
water

2. Measurement method of various parameters [Measurement of weight average molecular weight of polymer]
The weight average molecular weight of the polymer used for preparing the SWCNT dispersion to be separated was measured by gel permeation chromatography (hereinafter, also referred to as “GPC”) under the following conditions.
<GPC conditions>
Column: G4000PWXL + G2500PWXL (manufactured by Tosoh Corporation)
Eluent: 0.2M phosphate buffer / CH ₃ CN = 9/1 (volume ratio)
Flow rate: 1.0 mL / min
Column temperature: 40 ° C
Detection: RI
Sample size: 0.5 mg / mL
Standard substance: Polyethylene glycol equivalent

[Measurement of average diameter and average length of SWCNT]
The average diameter and average length of SWCNTs were calculated by measuring and averaging the diameters and lengths of 10 or more CNTs from images obtained using a transmission electron microscope.

3. 3. Preparation of semiconductor type SWCNT dispersion liquid [Examples 1 to 10, Reference Examples 1 to 6, Comparative Examples 1 to 3]
The SWCNT mixture shown in Tables 1 to 4 was added to 30 mL of a polyacrylic acid aqueous solution having a predetermined concentration in which polyacrylic acid was dissolved in ultrapure water to a predetermined concentration to obtain a SWCNT mixture to be separated. The mixed solution was defoamed for 1 minute using a miller (“Labor crusher OML1” manufactured by Osaka Chemical Co., Ltd., rotation speed 20000 rpm). Next, the defoaming treatment was performed for 1 minute using a dispersion defoaming device (“Awatori Rentaro AR-250” manufactured by Shinky Co., Ltd.). Next, the metal compounds shown in Tables 1 to 4 prepared at 1 mol / L were used. Add to a predetermined concentration, and disperse with an ultrasonic homogenizer (“450D” manufactured by BRANSON) under the conditions of AMPLITUDE 30% and 20 ° C. while stirring with a stirrer. Examples 1 to 10 and Reference Example. The SWCNT dispersions 1 to 6 and Comparative Examples 1 to 3 were obtained. The contents of the SWCNT mixture, polyacrylic acid, and metal compound in the SWCNT dispersions to be separated are as shown in Tables 1 to 4. , The water content is the residue after removing the SWCNT mixture, polyacrylic acid and metal compounds.
The obtained SWCNT dispersion liquid to be separated is subjected to an ultracentrifuge (“CS100GXII” manufactured by Hitachi Koki Co., Ltd., rotor S50A) at a rotation speed of 50,000 rpm, a gravitational acceleration of 210 kG, and 25 ° C. for 60 minutes. Centrifugation was performed. After that, 80% of the supernatant liquid was collected from the liquid surface on a volume basis so as not to fly up the precipitated deposit, and the semiconductor type SWCNT dispersion liquids of Examples 1 to 10, Reference Examples 1 to 6, and Comparative Examples 1 to 3 were collected. Got
[Example 11]
Ascorbic acid was prepared in advance in a 1 mol / L aqueous solution to the supernatant of Example 1, and added at 25 ° C. so that the concentration of ascorbic acid was 880 mass ppm (5 mmol / L). The semiconductor SWCNT dispersion liquid of the above was obtained. The addition of ascorbic acid was carried out immediately (within 1 minute) after the supernatant of Example 1 was obtained.

なお、使用したＳＷＣＮＴ（ＡＰＪおよびＳＯ）は、１０２０ｎｍ付近に半導体型ＳＷＣＮＴの固有波長を有し、７３０ｎｍ付近に金属型ＳＷＣＮＴの固有波長を有する。 4. Evaluation [Separability evaluation]
Absorbance is measured using an ultraviolet-visible near-infrared spectrophotometer (“UV-3600Plus” manufactured by Shimadzu Corporation) that can measure from visible light to infrared light. Then, a value obtained by taking the ratio of the peak intensity indicating the semiconductor type SWCNT to the peak intensity indicating the metal type SWCNT was calculated and used as an evaluation standard of the separability between the metal type SWCNT and the semiconductor type SWCNT. It can be evaluated that the higher the calculated value, the higher the semiconductor type SCNT separability. The results are shown in Tables 1-4.

The SWCNTs used (APJ and SO) have the intrinsic wavelength of the semiconductor SWCNT near 1020 nm and the intrinsic wavelength of the metal SWCNT near 730 nm.

[Dispersibility evaluation]
The peak intensity indicating the semiconductor type SWCNT was used as the evaluation standard for the dispersibility of the SWCNT. The higher the peak intensity value, the greater the recovery of the semiconductor type SWCNT, that is, the higher the dispersibility, and it can be evaluated that the dispersibility of the semiconductor type SWCNT is high. The evaluation results are shown in Tables 2 and 3.

As shown in Tables 1 to 4, the SWCNT dispersions separated in Examples 1 to 11 have the separability of semiconductor SWCNTs as compared with the SWCNT dispersions separated in Reference Examples 1 to 6 and Comparative Examples 1 to 3. Excellent for.

[Storing stability evaluation]
The storage stability of the semiconductor-type SWCNT dispersions of Examples 1 and 11 was evaluated as follows.
No. 15 mL of semiconductor type SWCNT dispersion liquid was added. It was placed in a 5-screw tube (manufactured by Maruem), sealed, left at room temperature for 1 month, and the presence or absence of a precipitate (non-eluting) was visually observed. If no precipitate (non-eluting) is confirmed, it can be evaluated that the storage stability is good. The results are shown in Table 5.

As shown in Table 5, the SWCNT dispersion of Example 1 to which ascorbic acid was not added was stable for several days, but a green cotton-like precipitate was observed after one month. On the other hand, the SWCNT dispersion liquid of Example 11 to which ascorbic acid was added showed no precipitate even after one month, and it was found that the storage stability was better than that of Example 1.

As described above, according to the method for producing a semiconductor-type SWCNT dispersion liquid of the present disclosure, the metal-type SWCNT and the semiconductor-type SWCNT can be separated in an aqueous medium without using a density gradient forming agent or the like. Since it can be carried out by using an easily available separating agent and a simple operation, it is expected that the manufacturing efficiency of the manufacturing method of the semiconductor type SWCNT dispersion liquid or the semiconductor type SWCNT itself can be improved.

Claims (15)

A single-walled carbon nanotube containing a semiconductor-type single-walled carbon nanotube and a metal-type single-walled carbon nanotube, an aqueous medium, and a polymer containing a structural unit A derived from a monomer represented by the following formula (1). Step A to prepare a single-walled carbon nanotube dispersion to be separated, which contains a reducing iron-containing material.
A step B of collecting a supernatant containing the semiconductor-type single-walled carbon nanotubes from the centrifuged single-walled carbon nanotube dispersion after centrifuging the single-walled carbon nanotube dispersion to be separated is included. ,
A method for producing a semiconductor-type single-walled carbon nanotube dispersion, wherein the polymer has a weight average molecular weight of 1,000 or more and 100,000 or less.
CH ₂ = CH-COMM (1)
In the formula (1), M represents a hydrogen atom, a metal atom, or a group having a structure represented by the following formula (2).

In formula (2), R ¹ , R ² , R ³ , and R ⁴ each independently represent an alkyl group having 1 or more and 2 or less carbon atoms which may have a hydrogen atom or a hydroxyl group. The semiconductor type single according to claim 1, wherein the content of the reducing iron-containing material in the single-walled carbon nanotube dispersion to be separated is 0.25 mmol / L or more and 18 mmol / L or less in terms of Fe atoms. A method for producing a layered carbon nanotube dispersion liquid. Claim 1 or 2 in which the mass ratio of the content (Fe atom equivalent) of the iron-containing material having reducibility to the content of the single-walled carbon nanotubes in the SWCNT dispersion liquid to be separated is 0.04 or more and 3 or less. The method for producing a semiconductor-type single-walled carbon nanotube dispersion liquid according to. The method for producing a semiconductor-type single-walled carbon nanotube dispersion liquid according to any one of claims 1 to 3, wherein the content of the structural unit A is 50 mol% or more among all the structural units contained in the polymer. The semiconductor type according to any one of claims 1 to 4, wherein the average diameter of the single-walled carbon nanotubes used for preparing the single-walled carbon nanotube dispersion to be separated in the step A is 0.5 nm or more and 2 nm or less. A method for producing a single-walled carbon nanotube dispersion liquid. The method for producing a semiconductor-type single-walled carbon nanotube dispersion liquid according to any one of claims 1 to 5, which comprises a step C of adding a reducing agent to the collected supernatant after the step B. The method for producing a semiconductor-type single-walled carbon nanotube dispersion liquid according to claim 6, wherein the content of the reducing agent in the supernatant to which the reducing agent is added is 0.05 mmol / L or more and 170 mmol / L. The method for producing a semiconductor-type single-walled carbon nanotube dispersion liquid according to claim 6 or 7, wherein the reducing agent is ascorbic acid. The semiconductor-type single-walled carbon nanotube dispersion obtained by the method for producing the semiconductor-type single-walled carbon nanotube dispersion according to any one of claims 1 to 8 is filtered to collect semiconductor-type single-walled carbon nanotubes. A method for manufacturing semiconductor-type single-walled carbon nanotubes, which includes steps. The semiconductor-type single-walled carbon nanotube dispersion obtained by the method for producing the semiconductor-type single-walled carbon nanotube dispersion according to any one of claims 1 to 8 is dried to obtain the semiconductor-type single-walled carbon nanotube and the polymer. And the process of obtaining a mixture containing
A method for producing semiconductor-type single-walled carbon nanotubes, which comprises a step of removing the polymer from the mixture and collecting semiconductor-type single-walled carbon nanotubes. A single-walled carbon nanotube containing a semiconductor-type single-walled carbon nanotube and a metal-type single-walled carbon nanotube, an aqueous medium, and a polymer containing a structural unit A derived from a monomer represented by the following formula (1). Step A to prepare a single-walled carbon nanotube dispersion to be separated, which contains a reducing iron-containing material.
A step B of collecting a supernatant containing the semiconductor-type single-walled carbon nanotubes from the centrifuged single-walled carbon nanotube dispersion after centrifuging the single-walled carbon nanotube dispersion to be separated is included. ,
A method for separating semiconductor-type single-walled carbon nanotubes and metal-type single-walled carbon nanotubes, wherein the polymer has a weight average molecular weight of 1,000 or more and 100,000 or less.
CH ₂ = CH-COMM (1)
In the formula (1), M represents a hydrogen atom, a metal atom, or a group having a structure represented by the following formula (2).

In formula (2), R ¹ , R ² , R ³ , and R ⁴ each independently represent an alkyl group having 1 or more and 2 or less carbon atoms which may have a hydrogen atom or a hydroxyl group. The method for separating semiconductor-type single-walled carbon nanotubes according to claim 11, further comprising step C of adding a reducing agent to the collected supernatant after step B. The method for separating a semiconductor-type single-walled carbon nanotube dispersion liquid according to claim 12, wherein the content of the reducing agent in the supernatant liquid to which the reducing agent is added is 0.05 mmol / L or more and 170 mmol / L. The method for separating semiconductor-type single-walled carbon nanotubes according to claim 12 or 13, wherein the reducing agent is ascorbic acid. A method for producing a semiconductor-type single-walled carbon nanotube-containing ink, which comprises the production method according to any one of claims 1 to 10 as one step.