JP2017112319A - Production method of dispersion composition, and production method of thermoelectric conversion layer - Google Patents

Abstract

An object of the present invention is to provide a method for producing a dispersion composition that can form a thermoelectric conversion layer with excellent dispersibility of carbon nanotubes, improved conductivity and thermoelectric conversion performance, and reduced variation in thermoelectric conversion performance, and It is providing the manufacturing method of a thermoelectric conversion layer.
A method for producing a dispersion composition of the present invention comprises a step A in which a carbon nanotube and an organic solvent are mixed to obtain a coarse dispersion composition, and a carbon nanotube film-like structure using the coarse dispersion composition. Step B for obtaining a product, Step C for obtaining a dispersion composition by mixing a dispersant, a solvent A, and the carbon nanotube film-like material of 1 w / v% or more with respect to the solvent A, Have.
[Selection figure] None

Description

  The present invention relates to a method for producing a dispersion composition and a method for producing a thermoelectric conversion layer.

  Thermoelectric conversion materials that can mutually convert thermal energy and electrical energy are used in thermoelectric conversion elements such as power generation elements and Peltier elements that generate electricity by heat. The thermoelectric conversion element can directly convert heat energy into electric power and does not require a movable part. For example, the thermoelectric conversion element is used for a wristwatch operating at body temperature, a power source for remote areas, a power source for space, and the like.

One typical configuration of the thermoelectric conversion element is a configuration in which a p-type thermoelectric conversion material and an n-type thermoelectric conversion material are electrically connected. Generally, n-type thermoelectric conversion materials include nickel and the like. Inorganic materials are known. However, inorganic materials have problems that the material itself is expensive, contains harmful substances, and that the processing process for the thermoelectric conversion element is complicated.
Therefore, in recent years, a technique using a carbon material typified by carbon nanotubes (hereinafter also referred to as “CNT”) has been proposed. For example, in Patent Document 1, a carbon nanotube and a dispersion medium are used as a high-speed rotating thin film dispersion method. A method for preparing a dispersion by use of the method is disclosed (claim 1, claim 9, etc.).

JP 2014-209573 A

In recent years, in order to improve the performance of equipment in which thermoelectric conversion elements are used, further improvement in thermoelectric conversion performance of thermoelectric conversion elements has been demanded. Specifically, forming a thick film using a dispersion used for forming a thermoelectric conversion layer included in a thermoelectric conversion element is one of the methods for further improving the above performance. However, it is required to increase the concentration of carbon nanotubes to a level that cannot be achieved by conventional techniques.
For example, when a dispersion containing a high concentration of carbon nanotubes was produced using a method as described in Patent Document 1, it was found that the dispersibility of the carbon nanotubes was lowered.
As described above, when the dispersibility of the carbon nanotubes in the dispersion becomes insufficient, the yield of the dispersion decreases, and the conductivity of the thermoelectric conversion layer obtained using the dispersion composition decreases, and the thermoelectric conversion performance ( The figure of merit Z) is lowered and the variation in thermoelectric conversion performance is deteriorated, resulting in a problem that the performance and reliability of the thermoelectric conversion element are lowered. This could not be greatly improved by studying the dispersion formula and conditions, and a new process had to be developed.

  Therefore, the present invention provides a method for producing a dispersion composition that can form a thermoelectric conversion layer with excellent dispersibility of carbon nanotubes, improved conductivity and thermoelectric conversion performance, and reduced variation in thermoelectric conversion performance, and thermoelectric conversion It is an object to provide a method for producing a layer.

As a result of earnestly examining the above problems, the present inventor prepared a coarse dispersion composition in which carbon nanotubes are dispersed in an organic solvent, and formed a carbon nanotube film-like material by forming a film of the coarse dispersion composition. Through the process of dispersing the carbon nanotube film in a solvent, it is possible to form a thermoelectric conversion layer with excellent carbon nanotube dispersibility, improved electrical conductivity and thermoelectric conversion performance, and reduced variation in thermoelectric conversion performance. And found the present invention.
That is, the present inventor has found that the above problem can be solved by the following configuration.

[1]
A step A in which a carbon nanotube and an organic solvent are mixed to obtain a coarse dispersion composition;
Step B for obtaining a carbon nanotube film using the coarse dispersion composition,
A step of obtaining a dispersion composition by mixing a dispersant, a solvent A, and the carbon nanotube film-like material of 1 w / v% or more with respect to the solvent A;
A method for producing a dispersion composition comprising:
[2]
In the said process C, the manufacturing method of the dispersion composition as described in said [1] which further adds a dopant.
[3]
The method for producing a dispersion composition according to [1] or [2], wherein a polymer compound is further added in the step C.
[4]
The method for producing a dispersion composition according to any one of [1] to [3], wherein the solvent A has a ClogP value of −0.5 or less.
[5]
The method for producing a dispersion composition according to any one of [1] to [4], wherein the solvent A is water.
[6]
The method for producing a dispersion composition according to any one of [1] to [5], wherein the dispersant is a surfactant.
[7]
In the said process A, the manufacturing method of the dispersion composition as described in any one of said [1]-[6] which mixes with a homogenizer.
[8]
In the said process C, the manufacturing method of the dispersion composition as described in any one of said [1]-[7] which mixes by a thin film swirl method.
[9]
The method for producing a dispersion composition according to any one of [1] to [8], wherein the carbon nanotube includes a single-walled carbon nanotube.
[10]
The manufacturing method of the dispersion composition as described in any one of said [1]-[9] used for formation of a thermoelectric conversion layer.
[11]
A step A in which a carbon nanotube and an organic solvent are mixed to obtain a coarse dispersion composition;
Step B for obtaining a carbon nanotube film using the coarse dispersion composition,
A step of obtaining a dispersion composition by mixing a dispersant, a solvent A, and the carbon nanotube film-like material of 1 w / v% or more with respect to the solvent A;
Step D for obtaining a thermoelectric conversion layer using the dispersion composition,
A method for producing a thermoelectric conversion layer.
[12]
In step C, a dopant is further added,
[11] The method further includes a step E of washing the thermoelectric conversion layer using the solvent B1 having an elution degree of the dispersant from the thermoelectric conversion layer higher than that of the dopant after the step D. The manufacturing method of the thermoelectric conversion layer of description.
[13]
In step C, a polymer compound is further added,
After the step D, the method further includes a step E of washing the thermoelectric conversion layer using a solvent B2 in which the elution degree of the dispersant from the thermoelectric conversion layer is higher than the elution degree of the polymer compound. [11] The method for producing a thermoelectric conversion layer of the thermoelectric conversion layer according to [11].
[14]
In step C, a dopant and a polymer compound are further added,
After the step D, the step E of washing the thermoelectric conversion layer using a solvent B3 in which the elution degree of the dispersant from the thermoelectric conversion layer is higher than any elution degree of the dopant and the polymer compound. Furthermore, the manufacturing method of the thermoelectric conversion layer as described in said [11].
[15]
In the said process C, the manufacturing method of the thermoelectric conversion layer as described in any one of said [11]-[14] which adds an antifoamer further.
[16]
The method for producing a thermoelectric conversion layer according to any one of [11] to [15], wherein the solvent A has a ClogP value of −0.5 or less.
[17]
The method for producing a thermoelectric conversion layer according to any one of [11] to [16], wherein the solvent A is water.
[18]
The method for producing a thermoelectric conversion layer according to any one of [11] to [17], wherein the dispersant is a surfactant.
[19]
In the said process A, the manufacturing method of the thermoelectric conversion layer as described in any one of said [11]-[18] which mixes with a homogenizer.
[20]
The method for producing a thermoelectric conversion layer according to any one of the above [11] to [19], wherein in the step C, mixing is performed by a thin film swirl method.
[21]
The method for producing a thermoelectric conversion layer according to any one of [11] to [20], wherein the carbon nanotubes include single-walled carbon nanotubes.

  As described below, according to the present invention, a dispersion composition capable of forming a thermoelectric conversion layer having excellent dispersibility of carbon nanotubes, improved conductivity and thermoelectric conversion performance, and reduced variation in thermoelectric conversion performance. The method and the manufacturing method of a thermoelectric conversion layer can be provided.

It is sectional drawing of the 1st embodiment of the thermoelectric conversion element of this invention. It is sectional drawing of the 2nd embodiment of the thermoelectric conversion element of this invention.

Below, the manufacturing method of the dispersion composition of this invention and the manufacturing method of a thermoelectric conversion layer are demonstrated.
In the present invention, a numerical range expressed using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.

In the present invention, the performance index Z is one of indexes for evaluating the thermoelectric conversion performance of the thermoelectric conversion element. This figure of merit Z is expressed by the following formula (A). For improvement of thermoelectric conversion performance, improvement of thermoelectromotive force (hereinafter sometimes referred to as thermoelectromotive force) S and conductivity σ per absolute temperature 1K, Reduction of thermal conductivity κ is important.
Figure of merit Z = S ² · σ / κ (A)
In the formula (A), S (V / K): thermoelectromotive force per 1 K absolute temperature (Seebeck coefficient)
σ (S / m): conductivity
κ (W / mK): thermal conductivity

[Method for producing dispersion composition]
The method for producing a dispersion composition of the present invention comprises a step A in which a carbon nanotube and an organic solvent are mixed to obtain a coarse dispersion composition, and a step in which a carbon nanotube film-like product is obtained using the coarse dispersion composition. B, a dispersing agent, a solvent A, and a step C for obtaining a dispersion composition by mixing 1% w / v or more of the carbon nanotube film-like material with respect to the solvent A.

According to the method for producing a dispersion composition of the present invention, a thermoelectric conversion layer having excellent dispersibility of carbon nanotubes, improved conductivity and thermoelectric conversion performance, and reduced variation in thermoelectric conversion performance can be formed. The relationship between the dispersion method and the performance related to thermoelectric conversion has not been clarified in the world, and the details of this reason have not been clarified yet, but it is presumed that the reason is as follows.
Carbon nanotubes (hereinafter also simply referred to as “CNT”) form a fibrous structure in which CNTs called bundles are bundled. Therefore, in order to loosen this bundle, CNT dispersion processing is performed. However, it is difficult to loosen these bundles at once, and there is a problem that undispersed CNTs that are thick bundles are likely to remain. When producing a dispersion composition containing CNT and a solvent, if the content of CNT with respect to the solvent is large, this problem becomes remarkable.
Thus, the inventors have intensively studied to form a coarse dispersion composition in which CNTs are dispersed in an organic solvent when producing a dispersion composition containing CNTs, and the resulting coarse dispersion composition is obtained. It has been found that the dispersibility of CNTs in the dispersion composition is excellent by performing in advance a step of forming a carbon nanotube film-like material by forming a carbon nanotube film. It was thought that once the CNTs were turned into a film-like lump, it was considered undesirable as a pretreatment for improving dispersibility, but surprisingly, this treatment significantly reduced the bundle of CNTs. It has been found that the dispersibility of CNTs in the dispersion composition is excellent.
Here, in order to make the bundle thin, it is necessary to make the dispersion condition strict, but it is known that remarkable improvement is difficult because it usually damages the CNT. However, in the present invention, by adopting a special process (the process of forming the above coarse dispersion composition and the process of forming a film-like material), the present invention succeeded in thinning the bundle while reducing damage to the CNT. it is conceivable that.
In this way, by forming a thermoelectric conversion layer using a dispersion composition containing CNTs having a small bundle diameter and few defects, CNTs are uniformly present in the layer. It is estimated that variation in conversion performance could be reduced.
In addition, since the bundle diameter of the CNTs in the dispersion composition is reduced, a good network between the CNTs is formed (that is, the number of contacts between the CNTs, which is the rate-determining of the conductivity, is increased). It is presumed that the electrical conductivity was improved. Moreover, it is thought that the thermoelectric conversion performance was also improved with the improvement of the electrical conductivity of the thermoelectric conversion layer.

  Hereafter, the process included in the manufacturing method of the dispersion composition of this invention and the process which may be included are demonstrated in detail.

[Process A]
Step A is a step in which a CNT and an organic solvent are mixed to obtain a coarse dispersion composition. By this step, a coarse dispersion composition in which CNTs are dispersed in an organic solvent is obtained. By this step, a bundle of CNTs is loosened to some extent, and a coarse dispersion composition in which CNTs are dispersed in an organic solvent is obtained.

The mixing of the CNT and the organic solvent is not limited to this. For example, homogenizer, thin film swirl, jaw crusher, automatic mortar, ultracentrifugation, jet mill, cutting mill, disk mill, ball mill, rotation revolution stirring, ultrasonic dispersion It can carry out using the apparatus which can implement methods, such as. Among these mixing methods, it is preferable to perform the mixing in the step A by a homogenizer or a jet mill from the viewpoint of easy control of the bundle diameter and the possibility of reducing the occurrence of defects in the CNT, and a homogenizer is used. It is more preferable. Moreover, you may combine two or more of these methods as needed.
The mixing conditions (mixing time, mixing temperature, etc.) are not particularly limited, but the conditions are such that the bundle diameter of CNTs in a film-like product in Step B described later is 200 nm or less. It is preferable that the reaction is performed under a condition that the thickness is 150 nm or less, and it is more preferable that the reaction is performed under a condition that the thickness is 100 nm or less. Thereby, the dispersibility of CNT in the dispersion composition in the subsequent process C is further improved. In particular, the use of the above-described homogenizer for mixing in the step A is preferable from the viewpoint that it is easy to make the bundle diameter of the CNT contained in the film-like material in the step B 200 nm or less.
In the present invention, the bundle diameter of CNT refers to the average minor axis diameter of the bundle of CNTs. The bundle diameter of the CNTs can be determined by checking the width of the fiber per bundle at 20 arbitrary positions, which can be confirmed from an image obtained by magnifying the film-like material in Step B by 50,000 times with a scanning electron microscope (SEM). It is the value which measured and calculated the average value.

(carbon nanotube)
The carbon nanotube (CNT) used in the step A of the present invention is a single-walled CNT in which one carbon film (graphene sheet) is wound in a cylindrical shape, a double-walled CNT in which two graphene sheets are wound in a concentric shape, There is a multilayer CNT in which a plurality of graphene sheets are wound concentrically. In the present invention, single-walled CNTs, double-walled CNTs, and multilayered CNTs may be used alone, or two or more kinds may be used in combination. In particular, it is preferable to use single-walled CNT and double-walled CNT having excellent properties in terms of conductivity and semiconductor properties, and more preferably single-walled CNT.
Single-walled CNTs may be semiconducting or metallic, and both may be used together, but those having a high content of semiconducting CNTs from the viewpoint of thermoelectric conversion performance. preferable. In addition, a metal or the like may be included in the CNT, and a substance in which a molecule such as fullerene is included (in particular, a substance in which fullerene is included is referred to as a peapod) may be used.
CNTs may be used alone or in combination of two or more.

CNT can be produced by an arc discharge method, a chemical vapor deposition method (hereinafter referred to as a CVD method), a laser ablation method, or the like. The CNT used in the present invention may be obtained by any method, but is preferably obtained by an arc discharge method and a CVD method.
When producing CNTs, fullerenes, graphite, and amorphous carbon may be produced as by-products at the same time. You may refine | purify in order to remove these by-products. Although the purification method of CNT is not specifically limited, Methods, such as washing | cleaning, centrifugation, filtration, oxidation, baking, and a chromatograph, are mentioned. In addition, acid treatment with nitric acid, sulfuric acid, etc. and ultrasonic treatment are also effective for removing impurities. In addition, it is more preferable to perform separation and removal using a filter from the viewpoint of improving purity.

After purification, the obtained CNT can be used as it is. Moreover, since CNT is generally produced in a string shape, it may be cut into a desired length depending on the application. CNTs can be cut into short fibers by acid treatment with nitric acid, sulfuric acid or the like, ultrasonic treatment, freeze pulverization method or the like. In addition, it is also preferable to perform separation using a filter from the viewpoint of improving purity.
In the present invention, not only cut CNTs but also CNTs produced in the form of short fibers in advance can be used in the same manner.

The average length of CNTs is not particularly limited, but is preferably 0.01 to 1000 μm, more preferably 0.1 to 100 μm, from the viewpoints of manufacturability, film formability, conductivity, and the like.
The diameter of the CNT is not particularly limited, but is preferably 0.4 to 100 nm, more preferably 0.5 to 4.0 nm, from the viewpoints of durability, film formability, conductivity, thermoelectric conversion performance, and the like. 6 to 3.0 nm is more preferable, and 0.7 to 2.0 nm is particularly preferable.
70% or more diameter distribution of CNT (hereinafter, “70% or more diameter distribution” is also simply referred to as “diameter distribution”) is preferably within 3.0 nm, and more preferably within 2.0 nm. , More preferably within 1.0 nm, particularly preferably within 0.7 nm.
The diameter and diameter distribution can be measured by the following method.
In this specification, the diameter of the single-walled carbon nanotube was evaluated as follows. That is, the Raman spectrum of the single-walled carbon nanotube with 532 nm excitation light was measured (excitation wavelength: 532 nm), and calculated from the radial breathing (RBM) mode shift ω (RBM) (cm ⁻¹ ) using the following calculation formula. . The value calculated from the maximum peak was taken as the CNT diameter. The diameter distribution was obtained from the distribution of each peak top.
Calculation formula: Diameter (nm) = 248 / ω (RBM)

  The amount of carbon nanotubes added in step A is preferably 0.001 to 50 w / v% and more preferably 0.01 to 25 w / v% with respect to the organic solvent added in step A. Preferably, it is more preferable that it is 0.01-10 w / v%. By being in this range, the bundle diameter in the film-like material in Step B can be controlled, and the dispersibility of the carbon nanotubes in Step C is improved.

(Organic solvent)
Examples of the organic solvent used in Step A of the present invention include methanol, ethanol, isopropanol, butanol, methoxyethoxyethanol, butoxyethanol, butyl carbitol, hexyloxyethanol, octanol, 1-methoxy-2-propanol, ethylene glycol and the like. Alcohol solvents, aliphatic halogen solvents such as chloroform, N, N-dimethylformamide (DMF), N, N-dimethylacetamide, N-methyl-2-pyrrolidone (NMP), N-ethyl-2-pyrrolidone, Aprotic polar solvents such as dimethyl sulfoxide (DMSO), chlorobenzene, dichlorobenzene, trichlorobenzene, benzene, toluene, ethylbenzene, xylene, mesitylene, tetralin, tetramethylbenzene, aniline , Aromatic solvents such as thioanisole, fluorobenzene, trifluoromethylbenzene, pyridine, quinoline, ketone solvents such as cyclohexanone, acetone, methyl ethyl kenton, methyl isobutyl ketone, diethyl ketone, isophorone, acetophenone, diethyl ether , THF (tetrahydrofuran), t-butyl methyl ether, diisopropyl ether, dimethoxyethane, dioxane, diglyme and other ether solvents, methyl acetate, ethyl acetate, butyl acetate, diacetoxypropane and other ester solvents, propylene glycol 1-monomethyl ether Examples include 2-acetate.
An organic solvent can be used individually by 1 type or in combination of 2 or more types.

[Process B]
Step B is a step of obtaining a carbon nanotube film (hereinafter also referred to as “CNT film”) using the coarse dispersion composition. Thereby, a sheet (cloth) -like CNT film is obtained. In this step, CNTs having a bundle diameter of 200 nm or less, preferably 150 nm, more preferably 100 nm or less are formed by forming the CNT film using the coarse dispersion composition obtained in Step A. It will be dispersed in a substantially uniform manner. By using such a CNT film-like material having a small bundle diameter in Step C, which will be described later, the dispersibility of CNT contained in the dispersion composition obtained in Step C becomes excellent. It is estimated that a dispersion liquid of was able to be obtained.

The method for forming the coarsely dispersed composition into a film is not particularly limited, and examples thereof include a method of obtaining a CNT film by removing the organic solvent by filtering the coarsely dispersed composition. The filtration is preferably carried out under reduced pressure from the viewpoint of improving the speed of solvent removal and improving the productivity of film formation.
The CNT film-like material can also be obtained by various methods such as printing, spraying, dip coating, and centrifugation.

In Step B, from the viewpoint of efficiently removing the organic solvent, a drying process for drying the CNT film-like material may be performed.
Although it does not specifically limit as conditions of a drying process, Generally, it is performed at 20-500 degreeC for 5 minutes-24 hours. The drying atmosphere is not particularly limited, and is performed in an air atmosphere, an inert gas atmosphere such as nitrogen or argon, or a reducing atmosphere such as argon / hydrogen. Moreover, it does not specifically limit as an apparatus used for a drying process, It can carry out using a well-known apparatus.

In Step B, the film thickness of the CNT film is not particularly limited, but is preferably 1 μm to 1 mm, more preferably 1 μm to 500 μm, from the viewpoint of CNT dispersibility in Step C described later.
Further, the mass per unit volume (density) of the CNT film-like material is preferably 0.01 to 1.2 g / cm ³ from the viewpoint that the dispersibility of CNT in the step C described later is further improved. more preferably 0.1 to 1.0 g / cm ^3, particularly preferably 0.3 to 0.8 g / cm ^3.

[Process C]
In Step C, a dispersing agent is obtained by mixing the dispersant, the solvent A, and the carbon nanotube film-like material of 1 w / v% or more, preferably 2 w / v% or more with respect to the solvent A. It is a process.

The mixing of each component in the process C is not limited to this, but for example, a homogenizer, a thin film swirl, a jaw crusher, an automatic mortar, an ultracentrifugal pulverization, a jet mill, a cutting mill, a disc mill, a ball mill, a roll mill, a rotation and revolution stirring, a super It can be performed using an apparatus capable of performing a method such as sonic dispersion. Among these methods, the mixing in the step C is preferably performed by a thin film swirl method. Moreover, you may perform these methods combining 2 or more.
Here, the thin film swirl method is a shear stress generated by centrifugal force and the difference in speed between the inner surface of the apparatus and the inner surface of the apparatus by rotating it at a high speed while being pressed against the inner surface (inner wall surface) of the apparatus. Is a dispersion method in which a dispersion target is dispersed in a thin-film cylindrical dispersion target. As an apparatus capable of performing the thin film swirl method, for example, a thin film swirl type high-speed mixer “FILMIX” (registered trademark) series (manufactured by Primix) can be suitably used.
The thin film swirl method disperses each component by centrifugal force and shear stress, and can suppress the cutting of CNTs and the occurrence of defects during mixing.
The mixing conditions (mixing time, mixing temperature, etc.) in step C are not particularly limited, and may be performed according to known conditions.

In step C, a defoaming treatment may be further performed for the purpose of defoaming the dispersion composition. For the defoaming treatment, a rotation and revolution stirring method is preferably used. Note that the defoaming treatment is not limited to the purpose of defoaming alone, and may be performed for the purpose of further mixing each component.
The conditions for defoaming treatment (defoaming time, temperature at the time of defoaming) are not particularly limited.

(Dispersant)
The dispersant is not particularly limited as long as it has a function of dispersing CNT, and a functional group adsorbed on CNT (for example, an aromatic group such as an alkyl group, pyrene, anthracene, terphenylene, porphyrin, etc.). Group, alicyclic groups such as cholesterol), steric repulsion groups (groups derived from polymers such as linear and branched alkyl groups, polyacrylates, etc.) that suppress the aggregation of CNTs, electrostatic repulsion groups (for example, , Carboxyl group, sulfonic acid group, phosphoric acid group salt, ammonium group, etc.) can be used regardless of whether it is a low molecular weight polymer or a high molecular weight material. Among these, a surfactant is preferably used. .
The surfactant is a compound having a portion (hydrophilic group) that is easily compatible with water and a portion (hydrophobic group) that is not easily compatible with water in the molecule. In the present specification, the surfactant may be a low molecular compound (a compound having a molecular weight of 1000 or less) or a polymer compound having a predetermined repeating unit.
The type of the surfactant is not particularly limited, and any known surfactant can be used as long as it has a function of dispersing CNTs. More specifically, various surfactants can be used as long as they are dissolved in water, a polar solvent, a mixture of water and a polar solvent, and have an adsorptivity to CNTs.
Examples thereof include ionic surfactants (anionic surfactants, cationic surfactants, amphoteric surfactants) and nonionic surfactants (nonionic surfactants). From the viewpoint of good dispersibility of CNTs, excellent thermoelectric conversion performance of the thermoelectric conversion layer, and easy removal by washing, an ionic surfactant is preferable, and an anionic surfactant is more preferable.

Examples of the anionic surfactant include fatty acid salts, abietic acid salts, hydroxyalkane sulfonates, alkane sulfonates, aromatic sulfonic acid surfactants, dialkyl sulfosuccinates, linear alkyl benzene sulfonates, branched Chain alkylbenzene sulfonates, alkylnaphthalene sulfonates, alkylphenoxy polyoxyethylene propyl sulfonates, polyoxyethylene alkyl sulfophenyl ether salts, sodium N-methyl-N-oleyl taurate, disodium N-alkylsulfosuccinate monoamide Salts, petroleum sulfonates, sulfated castor oil, sulfated beef tallow oil, sulfate esters of fatty acid alkyl esters, alkyl sulfate esters, polyoxyethylene alkyl ether sulfates Tell salt, fatty acid monoglyceride sulfate ester, polyoxyethylene alkylphenyl ether sulfate ester salt, polyoxyethylene styryl phenyl ether sulfate ester salt, alkyl phosphate ester salt, polyoxyethylene alkyl ether phosphate ester salt, polyoxyethylene alkylphenyl ether phosphate Ester salts, saponification products of styrene-maleic anhydride copolymer, saponification products of olefin-maleic anhydride copolymer, naphthalene sulfonate formalin condensates, aromatic sulfonates, aromatic substituted poly Examples thereof include oxyethylene sulfonates, monosoap anionic surfactants, ether sulfate surfactants, phosphate surfactants and carboxylic acid surfactants, and fatty acid salts.
More specifically, octylbenzene sulfonate, nonylbenzene sulfonate, dodecyl sulfonate, dodecyl benzene sulfonate, dodecyl diphenyl ether disulfonate, monoisopropyl naphthalene sulfonate, diisopropyl naphthalene sulfonate, triisopropyl Naphthalene sulfonate, dibutyl naphthalene sulfonate, naphthalene sulfonate formalin condensate, sodium cholate, potassium cholate, sodium deoxycholate, potassium deoxycholate, sodium glycocholate, sodium lithocholic acid, cetyltrimethylammonium bromide Etc.

Examples of the cationic surfactant include alkylamine salts and quaternary ammonium salts.
Examples of amphoteric surfactants include alkyl betaine surfactants and amine oxide surfactants.

Examples of nonionic surfactants include sugar ester surfactants such as sorbitan fatty acid esters and polyoxyethylene sorbitan fatty acid esters, and fatty acid ester surfactants such as polyoxyethylene resin acid esters and polyoxyethylene fatty acid diethyls. Glycerol fatty acid ester, pentaerythritol fatty acid ester, sorbitol and sorbitan fatty acid ester, sucrose fatty acid ester, polyhydric alcohol alkyl ether, alkanolamine fatty acid amide, polyoxyethylene alkyl ether , Ether surfactants such as polyoxyethylene alkylphenyl ether, polyoxyethylene / polypropylene glycol, polyoxyalkylene octylphenyl ether, polyoxyethylene Aromatic nonionic surface activity such as alkylene nonyl phenyl ether, polyoxyalkyl dibutyl phenyl ether, polyoxyalkyl styryl phenyl ether, polyoxyalkyl benzyl phenyl ether, polyoxyalkyl bisphenyl ether, polyoxyalkyl cumyl phenyl ether Agents.
As the nonionic surfactant, a so-called water-soluble polymer can be used, and for example, saccharide polymers such as polyvinyl alcohol, polyvinyl pyrrolidone, amylose, cycloamylose, and chitosan can be used.

Among such surfactants, ionic surfactants are preferable, and anionic surfactants are more preferable. Among these, cholate and deoxycholate are more preferably used.
By using ionic surfactants, particularly cholate and deoxycholate as surfactants, CNTs can be well dispersed in the dispersion composition. As a result, it is possible to form a thermoelectric conversion layer containing many CNTs that are long and have few defects, and thus a thermoelectric conversion element with better thermoelectric conversion performance can be obtained.
Further, since CNT can be dispersed at a high concentration, it is easy to increase the film thickness. As a result, high thermoelectric conversion performance can be obtained.

  The amount of the dispersant added is preferably 0.1 to 100 times, more preferably 1 to 10 times the mass of the carbon nanotubes contained in the dispersion composition obtained in Step C. It is particularly preferably 1 to 5 times. It exists in the tendency for the effect mentioned above to be exhibited more because the addition amount of a dispersing agent exists in the said range.

<Solvent A>
As the solvent A, water, an organic solvent, and a mixed solvent thereof can be used. As an organic solvent, since the organic solvent in the process A mentioned above is mentioned, the description is abbreviate | omitted.
As the solvent A, it is preferable to use a solvent having a ClogP value of −0.5 or less from the viewpoint of improving the adsorptivity of the CNT adsorbing group of the dispersant to CNT and further improving the dispersibility. More preferably, it is −2 to −0.5.
Examples of the solvent having a ClogP value of −0.5 or less include water (−1.38), methanol (−0.764), methoxyethanol (−0.606), and methoxyethoxyethanol (−0.742). , Dimethyl sulfoxide (−1.38), glycerol (−1.54) and the like, and water is preferable. These may be used alone or in admixture of two or more.

Here, the ClogP value is as follows.
First, the log P value means the common logarithm of the partition coefficient P (Partition Coefficient), and quantifies how a compound is distributed in the equilibrium of a two-phase system of oil (here, n-octanol) and water. It is a physical property value expressed as a numerical value. A larger number indicates a hydrophobic compound, and a smaller number indicates a hydrophilic compound. Therefore, it can be used as an index indicating the hydrophilicity / hydrophobicity of a compound. it can.

logP = log (Coil / Cwater)
Coil = Molar concentration in oil phase Cwater = Molar concentration in water phase

  In general, the logP value can also be obtained by actual measurement using n-octanol and water, but in the present invention, a distribution coefficient (ClogP value) (calculated value) obtained using a logP value estimation program is used. . Specifically, in this specification, the ClogP value obtained from “ChemBioDraw ultra ver.12” is used.

<Carbon nanotube film>
The carbon nanotube film (CNT film) is obtained by the process B described above. The CNT film may be cut into a desired size from the viewpoint of CNT dispersibility.
The addition amount of the CNT film-like material is 1 w / v% or more with respect to the addition amount of the solvent A, preferably 1 to 20 w / v%, and more preferably 2 to 20 w / v%. . When the added amount of the CNT film is within the above range, a dispersion composition having high CNT dispersibility is obtained in Step C, and the thermoelectric conversion performance of the resulting thermoelectric conversion layer is further improved. In particular, in the present invention, the amount of CNT film-like material added is as high as 1 w / t% or more with respect to the amount of solvent A added. The contradictory performance of increasing the concentration and improving the dispersibility of CNTs can be satisfied.
In the present invention, “w / v%” represents mass (g) / volume (ml).

<Dopant>
In at least one of step A and step C, it is preferable to add a dopant, and it is more preferable to add a dopant in step C. Thereby, the electrical conductivity and the figure of merit Z of the thermoelectric conversion layer obtained can be improved more.
The dopant may be added at the same timing as the above-described components are added, or may be added after mixing of the above-described components is completed.
As an addition amount in the case of adding a dopant, it is preferable that it is 0.01 to 3 times with respect to the mass of the carbon nanotube contained in the dispersion composition obtained at the process C, and 0.05 to 1 time. More preferably. The effect mentioned above is exhibited more because content of a dopant exists in the said range.
The dopant can be roughly classified into an n-type dopant and a p-type dopant depending on its polarity. Hereinafter, the compounds used as the n-type dopant and the p-type dopant will be described.

(N-type dopant)
The n-type dopant is not particularly limited as long as it can be reduced to n-type by reducing CNT or donating electrons, and a known dopant can be used.
Examples of the n-type dopant include amine compounds such as ammonia, tetramethylphenylenediamine, stearylamine, and polyethyleneimine, alkali metals such as potassium, triphenylphosphine, trioctylphosphine, and 1,3-bis (diphenylphosphine) propane. Phosphine compounds such as sodium borohydride, metal hydrides such as sodium borohydride and lithium aluminum hydride, reducing substances such as hydrazine and cobaltcene, electron donor compounds and the like can be used. Specifically, known compounds as described in Scientific Reports 3,3344 can be used.
In addition to the compounds described above, polyoxyalkylene compounds and amine compounds can also be used.
As the n-type dopant, a polyoxyalkylene compound is preferable.
These n-type dopants may be used alone or in combination of two or more.

  The polyoxyalkylene compound is not particularly limited as long as it is a compound having a polyalkylene oxide structure. Preferable examples of the alkylene oxide include ethylene oxide or propylene oxide, or a mixture thereof.

  Examples of polyoxyalkylene compounds that can be used in the present invention include polyethylene glycol type higher alcohol ethylene oxide adducts, ethylene oxide adducts such as phenol and naphthol, fatty acid ethylene oxide adducts, polyhydric alcohol fatty acid ester ethylene Oxide adduct, higher alkylamine ethylene oxide adduct, fatty acid amide ethylene oxide adduct, fat and oil ethylene oxide adduct, polypropylene glycol ethylene oxide adduct, dimethylsiloxane-ethylene oxide block copolymer, dimethylsiloxane- (propylene oxide-ethylene oxide) ) Block copolymer and the like. Of these, fatty acid ethylene oxide adducts, higher alcohol ethylene oxide adducts, and polypropylene glycol ethylene oxide adducts can be preferably used, and higher alcohol ethylene oxide adducts are particularly preferred. Examples of commercially available products include Emulgen, Rheodor, Emazol, Emanon, Amit (Kao Corporation), Pionin D, Pionine P, New Calgen D, Takesurf D (manufactured by Takemoto Yushi), Triton X (manufactured by Dow Chemical Company), Brij (manufactured by ICI Americas), Tween (manufactured by Atlas Powder), Nonident P-40 (manufactured by Shell Chemicals), Emalex CS (manufactured by Nippon Emulsion), New Coal (manufactured by Nippon Emulsifier), Leox, Lionol (made by Lion Specialty Chemical Co., Ltd.) can be used.

(P-type dopant)
The p-type dopant is not particularly limited as long as it can be converted to p-type by oxidizing CNT or the like, and a known dopant can be used.
For example, halogen (iodine, bromine etc.), Lewis acid (PF ₅ , AsF ₅ etc.), proton acid (hydrochloric acid, sulfuric acid, nitric acid etc.), transition metal halide (FeCl ₃ , SnCl ₄ etc.), organic electron accepting property Substances (tetracyanoquinodimethane derivatives such as tetracyanoquinodimethane, tetrafluorotetracyanoquinodimethane, 2,5-difluoro-7,7,8,8-tetracyanoquinodimethane, tetrafluoro-1,4 -Benzoquinone, 2,3-dichloro-5,6-dicyano-p-benzoquinone, chloranil, benzoquinone derivatives such as 2,6-dialkyl-1,4-benzoquinone, etc.).
An organic acid can also be used as the p-type dopant. Organic acid is a general term for organic compounds that exhibit acidity, and specifically includes carboxylic acid, sulfonic acid, sulfinic acid, sulfenic acid, phenol, enol, thiol, phosphonic acid, phosphoric acid, boronic acid, imidoic acid. A low molecular organic acid compound having a functional group showing acidity (hereinafter also referred to as an acidic functional group), such as hydrazoic acid, hydroxymic acid, hydroxysamic acid, or the like, or at least one acidic functional group and hydrophobic group. A low molecular organic acid compound, or an organic acid polymer having at least one acidic functional group in the molecule and having a repeating unit structure.
The acidic functional group may have any known structure, for example, carboxyl group, thiocarboxyl group, dithiocarboxyl group, mercaptocarbonyl group, hydroperoxy group, sulfo group, sulfino group, sulfeno group, phenolic hydroxyl group, Examples include a thiol group, a phosphate group, a phosphinico group, a phosphono group, a selenono group, a selenino group, a seleneno group, an arsinico group, an arsono group, a boronic acid group, and a boranoic acid group. Among these acidic functional groups, a carboxyl group, a phosphate group, a sulfo group, a thiol group, a phenolic hydroxyl group, and a boronic acid group are preferred in that the effect of the present invention (thermoelectric conversion performance and / or electrical stability) is more excellent. More preferred is a carboxyl group.

The number of acidic functional groups contained in the organic acid is not particularly limited as long as at least one acidic functional group is contained per molecule of the organic acid, but a plurality of acidic functional groups may be contained. In the case of a low molecular organic acid, the preferred range of the number of acidic functional groups in the organic acid is preferably 1 to 10, more preferably 1 to 6.
When a plurality of acidic functional groups are included in one organic acid molecule, the plurality of acidic functional groups may be the same or different from each other.

  In the present invention, the organic acid includes so-called anhydrides (organic acid anhydrides). An organic acid anhydride is a compound having a bond in which two acyl groups share an oxygen atom.

As described above, the organic acid may be an organic acid polymer having at least one acidic functional group in the molecule and a repeating unit structure. Examples of the organic acid polymer include polyvinyl sulfonic acid, polyvinyl phosphonic acid, polystyrene sulfonic acid, styrene / styrene phosphonic acid copolymer, polylactic acid, carboxymethyl cellulose, carboxyethyl cellulose, xanthan gum, carrageenan, pectin, polygalacturonic acid, alginic acid, Examples thereof include chondroitin sulfate, dermatan sulfate, heparan sulfate, hyaluronic acid, keratan sulfate, mucoitin sulfate, caronic acid, carrageenan, carboxymethyl chitin, carboxyvinyl polymer, polyacrylic acid, and acrylic acid / alkyl methacrylate copolymer. Moreover, what modified polysaccharide, protein, a synthetic polymer, etc. with acidic groups, such as a carboxy group, a carboxyalkyl group, a sulfo group, and a phosphate group is also contained. A part or all of the acidic groups of the polymer may be a salt such as a sodium salt, a potassium salt, or an ammonium salt.
Although there is no restriction | limiting in particular in the weight average molecular weight of the organic acid polymer used for this invention, 5000-10,000,000 are preferable and 10,000-5,000,000 are more preferable. In the present invention, the weight average molecular weight may be measured by gel permeation chromatography (GPC).

The boiling point of the organic acid is not particularly limited, but is preferably 200 ° C. or higher and more preferably 220 ° C. or higher in consideration of handleability and use as a thermoelectric conversion element.
This boiling point is intended to be a boiling point at 1 atmosphere, and is measured by, for example, an atmospheric pressure distillation test method according to JIS 2254, and the initial boiling point is used as the boiling point.
The melting point of the organic acid is not particularly limited, but it is preferably a solid acid in consideration of the use as a thermoelectric conversion element, and is preferably 100 ° C. or higher, more preferably 110 ° C. or higher, and 120 ° C. from the viewpoint of handleability. The above is more preferable. The upper limit is not particularly limited, but is preferably 300 ° C. or less from the viewpoint of handleability.
The melting point was measured according to JIS-0064, for example, using a differential scanning calorimeter manufactured by Perkin Elmer, product name: DSC7, and 10 mg of a sample was heated and melted under a nitrogen stream at a flow rate of 50 mL / min. After solidifying by cooling at a rate of 10 ° C./min, the melting peak temperature when the temperature is subsequently increased at a rate of 10 ° C./min is used.

As the p-type dopant, tetracyanoquinodimethane derivatives, benzoquinone derivatives, and organic acids are preferable.
These p-type dopants may be used alone or in combination of two or more.

<Polymer compound>
In at least one of Step A and Step C, it is preferable to add a polymer compound, and in Step C, it is more preferable to add a polymer compound. Since the polymer compound has a function as a binder, the distance between the CNTs can be increased. Thereby, since thermal conductivity can be lowered | hung, the figure of merit Z can be improved more.
The polymer compound may be added at the same timing as the above-described components are added, or may be added after mixing of the above-described components is completed.

Specific examples of the polymer compound include various known polymer compounds such as vinyl compounds, (meth) acrylate compounds, carbonate compounds, ester compounds, epoxy compounds, siloxane compounds, and gelatin. The polymer compound also has a function of increasing the distance between CNTs as a binder. For this reason, the obtained thermoelectric conversion layer has low thermal conductivity, and the figure of merit Z is improved. As the polymer compound, a hydrogen bonding resin is preferably used.
The hydrogen bonding functional group may be any functional group having hydrogen bonding properties, for example, OH group, NH ₂ group, NHR group (R represents an aromatic or aliphatic hydrocarbon), COOH group, CONH. ₂ groups, NHOH group, SO ₃ H group (sulfonic acid group), —OP (═O) OH ₂ group (phosphoric acid group), etc., —NHCO— group, —NH— group, —CONHCO— bond, —NH —NH— bond, —C (═O) — group (carbonyl group), —ROR— group (ether group: R each independently represents a divalent aromatic hydrocarbon or a divalent aliphatic hydrocarbon. However, two R may be same or different.) Etc. are mentioned.
Examples of hydrogen bonding resins include carboxymethyl cellulose, carboxyethyl cellulose, methyl cellulose, ethyl cellulose, hydroxymethyl cellulose, hydroxyethyl cellulose, methyl hydroxypropyl cellulose, hydroxypropyl methyl cellulose, crystalline cellulose, xanthan gum, guar gum, hydroxyethyl guar gum, carboxymethyl guar gum, tragacanth gum , Locust bean gum, tamarind seed gum, psyllium seed gum, quince seed, carrageenan, galactan, gum arabic, pectin, pullulan, mannan, glucomannan, starch, curdlan, carrageenan, chondroitin sulfate, dermatan sulfate, glycogen, heparan sulfate, Hyaluronic acid, hyaluronic acid, kerata Sulfuric acid, chondroitin, mucoitin sulfate, dextran, keratosulfate, succinoglucan, carolinic acid, alginic acid, propylene glycol alginate, macrogol, chitin, chitosan, carboxymethylchitin, gelatin, agar, curdlan, polyvinyl alcohol, polyvinylpyrrolidone, carboxy Vinyl polymer, alkyl-modified carboxyvinyl polymer, polyacrylic acid, acrylic acid / alkyl methacrylate copolymer, polyethylene glycol, (hydroxyethyl acrylate / acryloyldimethyltaurine sodium) copolymer, (acryloyldimethyltaurine ammonium / vinylpyrrolidone) copolymer, Starch, modified starch, bentonite and the like can be mentioned. In addition, what has acidic groups, such as a carboxyl group, may partly or entirely become salts, such as a sodium salt, potassium salt, and ammonium salt.

  The amount of the polymer compound added is preferably 0.01 to 5 times, preferably 0.1 to 3 times the mass of the carbon nanotubes in the dispersion composition obtained in Step C. It is more preferable that the ratio is 0.1 to 1 times.

The weight average molecular weight of the polymer compound is preferably 5,000 to 10,000,000, more preferably 10,000 to 5,000,000, and 50,000 to 5,000,000. It is particularly preferred. The weight average molecular weight is measured by gel permeation chromatography (GPC).
GPC uses a HLC-8220GPC (manufactured by Tosoh Corporation), TSKgel G5000PW _XL as a _{column, TSKgel G4000PW XL, TSKgel G2500PW XL} ( Tosoh, 7.8 mm ID × 30 cm) using a 10 mM NaNO ₃ solution as eluent Use. In addition, as conditions, the sample concentration is 0.1% by mass, the flow rate is 1.0 ml / min (reference is 0.5 ml / min), the sample injection amount is 100 μl, the measurement temperature is 40 ° C., and the RI detector is used. Do it.
In addition, the calibration curve is TSK standard POLY (ETHILENE OXIDE): “SE-150”, “SE-30”, “SE-8”, “SE-5”, “SE-2” (manufactured by Tosoh), molecular weight 3000 It is made from polyethylene glycol and hexaethylene glycol having a molecular weight of 282.

<Antifoaming agent>
In step C, it is preferable to add an antifoaming agent.
As in the present invention, a dispersion composition containing a high concentration of carbon nanotubes has a high viscosity and is difficult to degas. If the defoaming in the dispersion composition is insufficient, voids are formed in the film after film formation and drying, causing a decrease in conductivity. Therefore, it is preferable to defoam the dispersion composition, and the addition of an antifoaming agent is useful.
The antifoaming agent may be added at the same timing as the above-described components are added, or may be added after mixing of the above-described components is completed.
The antifoaming agent is not particularly limited as long as it reduces the surface tension of the dispersion composition and has an affinity for the solvent A. For example, highly oxidized oil type, fatty acid ester type, fluorine type, silicone type compound and the like can be mentioned. Those having a low affinity for the solvent A can also be used as an emulsion.
An antifoamer may be used independently, or may mix and use 2 or more types.
The content of the antifoaming agent is preferably 0.0001 to 10% by mass, more preferably 0.001 to 5% by mass, and more preferably 0.005 to 1% with respect to the total mass of the dispersion composition. More preferably, it is mass%.

<Other ingredients>
In step C, components other than those described above may be added. In this case, components other than those described above may be added at the same timing as the above-described components are added, or may be added after mixing of the above-described components is completed.
Examples of components other than the above include antioxidants, antifungal agents, light-resistant stabilizers, heat-resistant stabilizers, and plasticizers.

[Method for producing thermoelectric conversion layer]
The method for producing a thermoelectric conversion layer of the present invention includes a step A of obtaining a coarsely dispersed composition by mixing carbon nanotubes and an organic solvent, and a step of obtaining a carbon nanotube film-like product using the coarsely dispersed composition. B, a dispersant, a solvent A, and a process C for obtaining a dispersion composition by mixing 1% w / v or more of the carbon nanotube film-like material with respect to the solvent A; and the dispersion composition And D for obtaining a thermoelectric conversion layer.
About the said process A-process C, since it is the same as that of the manufacturing method of the dispersion composition mentioned above and the component used is the same, the description is abbreviate | omitted.
Hereinafter, the process D and the process which may be included are demonstrated in detail about the manufacturing method of the thermoelectric conversion layer of this invention.

[Process D]
Step D is a step of obtaining a thermoelectric conversion layer using the dispersion composition.
Specifically, the step D includes a method of coating the dispersion composition on a base material and forming a film.
The film forming method is not particularly limited. For example, screen printing, metal mask printing, stencil printing, printing using a dispenser, die coating, blade coating, bar coating, gravure printing, roll coating, curtain coating, dip coating, Known coating methods such as ink jet printing and spray coating can be used. Among these, the dispersion composition is preferably a printing method such as metal mask printing, screen printing, or stencil printing because it is excellent in printability even when it has a high solid content concentration and a high viscosity. In particular, metal mask printing and screen printing are particularly preferred in that the dispersion composition can be printed on a thick coating film by a single coating.
The screen printing method includes patterning exposure of a photosensitive resin on a normal mesh made of stainless steel, nylon, and polyester, developing it to produce a plate, printing, and producing a plate from an etched metal mask. And printing methods.
Moreover, after application | coating, a drying process is performed as needed. It does not specifically limit as drying conditions, What is necessary is just to carry out on well-known conditions. For example, in the drying process, an oven, a pot plate, a hot air dryer, a far infrared dryer, or the like can be used.

[Process E]
Step E is a step of washing the thermoelectric conversion layer with solvent B, and can take the following three modes depending on the components added in step A and step C.
The first aspect is an aspect in which the dopant described above is further added in at least one of the process A and the process C, and the process E performed in this aspect is hereinafter referred to as “process E1”.
The second embodiment is an embodiment in which the above-described polymer compound is further added in at least one of step A and step C, and step E performed in this embodiment is hereinafter referred to as “step E2”.
The third aspect is an aspect in which the dopant and the polymer compound described above are further added in at least one of the process A and the process C, and the process E performed in this aspect is hereinafter referred to as “process E3”.
In step E, step E1, step E2, or step E3 is performed. Hereinafter, each of the process E1, the process E2, and the process E3 will be described.
In this specification, the solvent B1 described later used in the step E1, the solvent B2 described later used in the step E2, and the solvent B3 described later used in the step E3 are collectively referred to as “solvent B”. There is.

<Process E1>
The step E1 is a step that can be performed when a dopant is added in at least one of the step A and the step C. After the step D, the elution degree of the dispersant from the thermoelectric conversion layer is This is a step of washing the thermoelectric conversion layer using a solvent B1 having a higher elution degree of the dopant. In addition, as above-mentioned, it is preferable that the said dopant is added in the process C.
By this step, since the dispersant contained in the thermoelectric conversion layer can be removed while suppressing elution of the dopant, the figure of merit Z of the thermoelectric conversion layer can be further improved.
The elution degree of each component from the thermoelectric conversion layer is measured by the method described in the Examples section described later.

The solvent B1 is not particularly limited as long as each component satisfies the above-described elution degree relationship depending on the dispersant and the dopant to be used. For example, the water, organic solvent, and those mentioned above for the solvent A Two or more kinds of mixed solvents can be used.
For example, when the dispersant is a surfactant, ClogP is preferably −2 to 1 and preferably −2 to 0.2 as the solvent B1 from the viewpoint of satisfying the above-described elution degree relationship. More preferred.
Examples of the solvent B1 include water (−1.38), methanol (−0.764), acetonitrile (−0.394), 1-methoxy-2-propanol (−0.297), ethanol (−0. 235), acetone (−0.208), ethylene glycol monomethyl ether (−0.606), propanol (0.294), isopropanol (0.074), N-ethylpyrrolidone (0.132), propionitrile ( 0.135), methyl acetate (0.182), 2-butanone (0.321), tetrahydrofuran (0.526), propylene glycol 1-monomethyl ether 2-acetate (0.599), ethyl acetate (0.711) ), Cyclohexanone (0.865), chloroform (0.936) and the like. In addition, the numerical value in a parenthesis represents a ClogP value.
Solvent B1 may be used independently or may be used in mixture of 2 or more types.

The amount of solvent B1 used in step E1 is not particularly limited.
The cleaning method in the step E1 is not particularly limited. For example, a method of immersing the thermoelectric conversion layer in the solvent B1, a method of rinsing the thermoelectric conversion layer with the solvent B1, a method of spraying the solvent B1 on the thermoelectric conversion layer, and the like. Can be performed.
Moreover, the conditions at the time of washing (the temperature of the solvent B1, the washing time, etc.) are not particularly limited.

<Process E2>
Step E2 is a step that can be performed when the polymer compound is added in at least one of Step A and Step C. After Step D, the dispersant from the thermoelectric conversion layer is added. This is a step of washing the thermoelectric conversion layer using a solvent B2 having an elution degree higher than that of the polymer compound. As described above, the polymer compound is preferably added in Step C.
By this step, since the dispersant contained in the thermoelectric conversion layer can be removed while suppressing the elution of the polymer compound, the figure of merit Z of the thermoelectric conversion layer can be further improved.
The elution degree of each component from the thermoelectric conversion layer is measured by the method described in the Examples section described later.
The solvent B2 is not particularly limited depending on the dispersant and polymer compound to be used as long as each component satisfies the above-described elution degree relationship, and the solvent B2 mentioned above in the step E1 is used. Since the preferred embodiment is the same, the description thereof is omitted.
The amount of solvent B2 used in step E2 is not particularly limited.
It does not specifically limit as a washing | cleaning method in process E2, The method quoted by process E1 mentioned above can be used.
The conditions at the time of washing (the temperature of the solvent B2, the washing time, etc.) are not particularly limited.

<Process E3>
Step E3 is a step that can be performed when the dopant and the polymer compound are added in at least one of Step A and Step C. After Step D, the step from the thermoelectric conversion layer is performed. In this step, the thermoelectric conversion layer is washed with the solvent B3 having a higher elution degree of the dispersant than that of any of the dopant and the polymer compound. In addition, as above-mentioned, it is preferable that the said dopant and the said high molecular compound are added in the process C.
By this step, since the dispersant contained in the thermoelectric conversion layer can be removed while suppressing elution of the dopant and the polymer compound, the figure of merit Z of the thermoelectric conversion layer can be further improved.
The elution degree of each component from the thermoelectric conversion layer is measured by the method described in the Examples section described later.
Solvent B3 is not particularly limited depending on the dispersant, dopant, and polymer compound to be used, as long as each component satisfies the above-described elution degree relationship, and the solvent B3 mentioned above in Step E1 is used. The preferred embodiment is the same, and the description thereof is omitted.
The amount of solvent B3 used in step E3 is not particularly limited.
It does not specifically limit as a washing | cleaning method in process E3, The method quoted by process E1 mentioned above can be used.
The conditions at the time of washing (the temperature of the solvent B3, the washing time, etc.) are not particularly limited.

[Thermoelectric conversion element]
If the thermoelectric conversion element of this invention is equipped with the thermoelectric conversion layer of this invention mentioned above, the structure will not be restrict | limited in particular. Below, the thermoelectric conversion element of this invention is demonstrated.

[First Embodiment]
In FIG. 1, sectional drawing of the 1st embodiment of the thermoelectric conversion element of this invention is shown.
The thermoelectric conversion element 110 illustrated in FIG. 1 includes a pair of electrodes including a first electrode 13 and a second electrode 15 on a first base 12 and a gap between the first electrode 13 and the second electrode 15. The thermoelectric conversion layer 14 is provided.

[Second Embodiment]
In FIG. 2, sectional drawing of the 2nd embodiment of the thermoelectric conversion element of this invention is shown.
In the thermoelectric conversion element 120 shown in FIG. 2, a first electrode 23 and a second electrode 25 are disposed on a first base material 22, and a thermoelectric conversion layer 24 is provided thereon.

  Hereinafter, the present invention will be described in detail with reference to examples. However, the present invention is not limited to this.

[Example 1]
<Process A>
Single-walled CNT 500 mg (Tuball manufactured by OCSiAl) and 250 mL of acetone were mixed for 5 minutes at 18000 rpm using a mechanical homogenizer (manufactured by SMT Co., Ltd., HIGH-FLEX HOMOGENIZER HF93) to obtain a coarse dispersion composition.
<Process B>
The obtained coarse dispersion composition was filtered under reduced pressure using a Buchner funnel and a suction bottle to obtain a cloth-like CNT film (bucky paper) as a CNT film-like material. The cloth-like CNT film was cut into a size of about 3.5 mm square and used to prepare the dispersion composition 1 in the next step.
<Process C>
Sodium deoxycholate 1200 mg (manufactured by Tokyo Chemical Industry Co., Ltd., dispersant) was dissolved in 16 mL of water (solvent A), pretreated, and 160 mg of a cloth-like CNT film cut to a size of about 3.5 mm square was added. This composition was mixed for 7 minutes using a mechanical homogenizer (manufactured by SMT Co., Ltd., HIGH-FLEX HOMOGENIZER HF93) to obtain a preliminary mixture. Using the thin film swirl type high-speed mixer “Filmix 40-40” (manufactured by Primics), the obtained preliminary mixture was placed in a thermostatic layer at 10 ° C. for 2 minutes at a peripheral speed of 10 m / sec, and then at a peripheral speed of 40 m / sec. For 5 minutes. The obtained composition was mixed at 2000 rpm for 30 seconds with a rotating / revolving mixer (Shinky Co., Ltd., Nertaro Awatori), and defoamed at 2200 rpm for 30 seconds to prepare dispersion composition 1.
<Process D>
Using dispersion composition 1, printing was performed by metal mask printing to produce a printed material having a 1 cm square size on polyimide. The obtained printed matter was dried at 50 ° C. for 30 minutes and at 120 ° C. for 30 minutes.
<Process E>
The printed matter after drying was immersed in ethanol (solvent B) for 1 hour to remove the dispersant in the printed matter. Then, the thermoelectric conversion layer 1 was obtained by drying at 50 ° C. for 30 minutes and at 120 ° C. for 150 minutes.

[Example 2]
In Step C, a dispersion composition 2 and a thermoelectric conversion layer 2 were obtained in the same manner as in Example 1, except that the single-walled CNT was changed from 160 mg to 400 mg.

[Example 3]
A dispersion composition 3 and a thermoelectric conversion layer 3 were obtained in the same manner as in Example 2 except that the single-walled CNT was changed from Tuball manufactured by OCSiAl to EC1.5 manufactured by Meijo Nanocarbon.

[Example 4]
A dispersion composition 4 and a thermoelectric conversion layer 4 were obtained in the same manner as in Example 2 except that the single-walled CNT was changed from Tuball manufactured by OCSiAl to HP manufactured by KH Chemical.

[Example 5]
In the preparation of the dispersion composition 2 in Example 2 (Step C), except that 200 mg of tetracyanoquinodimethane (manufactured by Wako Pure Chemical Industries, Ltd., dopant, hereinafter also referred to as “TCNQ”) was added to the preliminary mixture. In the same manner as in Example 2, a dispersion composition 5 and a thermoelectric conversion layer 5 were obtained.

[Example 6]
In the preparation of the dispersion composition 2 in Example 2 (step C), sodium deoxycholate 1200 mg (manufactured by Tokyo Chemical Industry Co., Ltd., dispersant) and carboxymethylcellulose sodium salt 100 mg (manufactured by Aldrich, high viscosity product, polymer compound). Hereinafter, the dispersion composition 6 and the thermoelectric conversion layer 6 were obtained in the same manner as in Example 2 except that “CMC-Na”) was dissolved in 16 mL of water.

[Example 7]
In preparation of dispersion composition 2 in Example 2 (step C), sodium deoxycholate 1200 mg (manufactured by Tokyo Chemical Industry Co., Ltd., dispersant) and sodium carboxymethylcellulose 100 mg (manufactured by Aldrich, high viscosity product, polymer compound) Was dissolved in 16 mL of water, and the dispersion composition 7 and the thermoelectric conversion layer 7 were prepared in the same manner as in Example 2 except that 200 mg of tetracyanoquinodimethane (manufactured by Wako Pure Chemical Industries, dopant) was added to the preliminary mixture. Obtained.

[Example 8]
In the preparation of the dispersion composition 2 in Example 2 (Step C), the sodium deoxycholate was changed to sodium cholate, and the ethanol was changed to methanol in the step E in Example 2 as in Example 2. Thus, a dispersion composition 8 and a thermoelectric conversion layer 8 were obtained.

[Example 9]
In preparation of the dispersion composition 8 in Example 8 (step C), 200 mg of 2,3-dichloro-5,6-dicyano-p-benzoquinone (manufactured by Wako Pure Chemical Industries, Ltd., dopant, hereinafter referred to as “DDQ”) was added to the pre-mixture. .) Was added in the same manner as in Example 8 except that a dispersion composition 9 and a thermoelectric conversion layer 9 were obtained.

[Example 10]
100 mg of alginic acid (manufactured by Wako Pure Chemical Industries, Ltd., polymer compound) was added to the dispersion composition 8 in Example 8 and mixed for 60 seconds at 2000 rpm with a rotating / revolving mixer (manufactured by Shinky Co., Ltd., Kentaro Awatori) at 2200 rpm. The dispersion composition 10 was prepared by defoaming for 60 seconds.
And the thermoelectric conversion layer 10 was obtained like Example 8 except having used the dispersion composition 10 instead of the dispersion composition 8. FIG.

[Example 11]
100 mg of alginic acid (polymer compound, manufactured by Wako Pure Chemical Industries, Ltd.) was added to the dispersion composition 9 in Example 9, and mixed for 60 seconds at 2000 rpm with a rotating / revolving mixer (Shinky Corp., Kentaro Awatori) at 2200 rpm. The dispersion composition 11 was prepared by defoaming for 60 seconds.
And the thermoelectric conversion layer 11 was obtained like Example 9 except having used the dispersion composition 11 instead of the dispersion composition 9. FIG.

[Example 12]
In the preparation of the dispersion composition 2 in Example 2 (Step C), 2400 mg of sodium deoxycholate (manufactured by Tokyo Chemical Industry Co., Ltd.) and the cloth-like CNT film cut to a size of about 3.5 mm square were changed to 800 mg. A dispersion was prepared in the same manner as in Example 2 except for the above. To this, 50 mg of xanthan gum (manufactured by Wako Pure Chemical Industries, Ltd., polymer compound) was added, and the mixture was defoamed at 2000 rpm for 60 seconds at 2200 rpm with a rotating / revolving mixer (Shinky Corporation, Aritori Nertaro). A dispersion composition 12 was prepared.
And the thermoelectric conversion layer 12 was obtained like Example 2 except having used the dispersion composition 12 instead of the dispersion composition 2, and having changed ethanol into isopropanol in the process E in Example 2. FIG.

[Example 13]
In the preparation of the dispersion composition 12 in Example 12 (Step C), the dispersion was performed in the same manner as in Example 12 except that 200 mg of tetracyanoquinodimethane (manufactured by Wako Pure Chemical Industries, Ltd., dopant) was added to the preliminary mixture. A composition 13 was obtained.
And the thermoelectric conversion layer 13 was obtained like Example 12 except having used the dispersion composition 13 instead of the dispersion liquid 12, and having changed isopropanol into water in the process E in Example 12. FIG.

[Example 14]
<Process A>
Single-walled CNT 500 mg (Tucall manufactured by OCSiAl) and 2-butanone 250 mL were mixed for 5 minutes at 18000 rpm using a mechanical homogenizer (manufactured by SMT Co., Ltd., HIGH-FLEX HOMOGENIZER HF93) to obtain a coarse dispersion composition.
<Process B>
The obtained coarse dispersion composition was filtered under reduced pressure using a Buchner filter funnel and a suction bottle to obtain a cloth-like CNT film (bucky paper) as a CNT film. The cloth-like CNT film was cut into a size of about 3.5 mm square and used to prepare the dispersion composition 14 in the next step.
<Process C>
Sodium deoxycholate 1200 mg (manufactured by Tokyo Kasei Kogyo Co., Ltd., dispersing agent), Emulgen 350 (manufactured by Kao Co., Ltd., dispersing agent) 400 mg was dissolved in 16 mL of water, pretreated, and cut into a size of about 3.5 mm square 400 mg of CNT film was added. This composition was mixed for 7 minutes using a mechanical homogenizer (manufactured by SMT Co., Ltd., HIGH-FLEX HOMOGENIZER HF93) to obtain a preliminary mixture. Using the thin film swirl type high-speed mixer “Filmix 40-40” (manufactured by Primics), the obtained preliminary mixture was placed in a thermostatic layer at 10 ° C. for 2 minutes at a peripheral speed of 10 m / sec, and then at a peripheral speed of 40 m / sec. For 5 minutes. The obtained composition was mixed at 2000 rpm for 30 seconds with a rotating / revolving mixer (Shinky Co., Ltd., Nertaro Awatori), and defoamed at 2200 rpm for 30 seconds to prepare dispersion composition 14.
<Process D to Process E)
A thermoelectric conversion layer 14 was obtained in the same manner as in Example 2 except that the dispersion composition 14 was used instead of the dispersion composition 2.

[Example 15]
<Process A>
Single-walled CNT 500 mg (Tuball manufactured by OCSiAl) and 250 mL of isopropanol were mixed for 5 minutes at 18000 rpm using a mechanical homogenizer (manufactured by SMT Co., Ltd., HIGH-FLEX HOMOGENIZER HF93) to obtain a coarse dispersion composition.
<Process B>
The obtained coarse dispersion composition was filtered under reduced pressure using a Buchner funnel and a suction bottle to obtain a cloth-like CNT film (bucky paper) as a CNT film-like material. The cloth-like CNT film was cut into a size of about 3.5 mm square and used to prepare the dispersion composition 15 in the next step.
<Process C>
Dissolve sodium deoxycholate 1200 mg (manufactured by Tokyo Chemical Industry Co., Ltd., dispersant), sodium carboxymethylcellulose 200 mg (low viscosity, Aldrich, polymer compound), emulgen 350 (manufactured by Kao Corporation, dopant) 400 mg in 16 mL of water. Then, 400 mg of a cloth-like CNT film pretreated and cut to a size of about 3.5 mm square was added. This composition was mixed for 7 minutes using a mechanical homogenizer (manufactured by SMT Co., Ltd., HIGH-FLEX HOMOGENIZER HF93) to obtain a preliminary mixture. Using the thin film swirl type high-speed mixer “Filmix 40-40” (manufactured by Primics), the obtained preliminary mixture was placed in a thermostatic layer at 10 ° C. for 2 minutes at a peripheral speed of 10 m / sec, and then at a peripheral speed of 40 m / sec. For 5 minutes. The resulting composition was mixed at 2000 rpm for 30 seconds with a rotating / revolving mixer (Shinky Corp., Aritori Kentaro), and defoamed at 2200 rpm for 30 seconds to prepare dispersion composition 15.
<Process D to Process E)
A thermoelectric conversion layer 15 was obtained in the same manner as in Example 2 except that the dispersion composition 15 was used instead of the dispersion composition 2.

[Example 16]
A dispersion composition 16 and a thermoelectric conversion layer 16 were obtained in the same manner as in Example 5 except that sodium deoxycholate was replaced with sodium dodecylbenzenesulfonate.

[Example 17]
Sodium deoxycholate is sodium dodecylbenzenesulfonate and tetracyanoquinodimethane is 2,5-bis (hydroxyethoxy) tetracyanoquinodimethane (manufactured by Wako Pure Chemical Industries, Ltd., dopant. Hereinafter, “2,5-bis (2 A dispersion composition 17 and a thermoelectric conversion layer 17 were obtained in the same manner as in Example 5, except that the term “-hydroxyethoxy) TCNQ” was used.

[Example 18]
22 mg of antifoaming agent KM-85 (manufactured by Shin-Etsu Silicone) is added to dispersion composition 2 in Example 2, and mixed at 2000 rpm for 30 seconds with a rotating / revolving mixer (manufactured by Shinky Co., Ltd., Kentaro Awatori) at 2200 rpm. A dispersion composition 18 was prepared by defoaming for 30 seconds.
And the thermoelectric conversion layer 18 was obtained like Example 2 except having used the dispersion composition 18 instead of the dispersion composition 2. FIG.

[Example 19]
22 mg of antifoaming agent KM-85 (manufactured by Shin-Etsu Silicone) was added to dispersion composition 7 in Example 7, and mixed for 30 seconds at 2000 rpm with a rotating / revolving mixer (manufactured by Shinky Co., Ltd., Kentaro Awatori) at 2200 rpm. A dispersion composition 19 was prepared by defoaming for 30 seconds.
And the thermoelectric conversion layer 19 was obtained like Example 7 except having used the dispersion composition 19 instead of the dispersion composition 7. FIG.

[Example 20]
22 mg of antifoaming agent KM-85 (manufactured by Shin-Etsu Silicone) was added to dispersion composition 15 in Example 15, and mixed for 30 seconds at 2000 rpm with a rotating / revolving mixer (manufactured by Shinky Co., Ltd., Kentaro Awatori) at 2200 rpm. A dispersion composition 20 was prepared by defoaming for 30 seconds.
And the thermoelectric conversion layer 20 was obtained like Example 15 except having used the dispersion liquid composition 20 instead of the dispersion composition 15. FIG.

[Example 21]
A dispersion composition 21 and a thermoelectric conversion layer 21 were obtained in the same manner as in Example 2 except that washing with ethanol was not performed.

[Comparative Example 1]
Dispersion composition c1 and thermoelectric conversion were carried out in the same manner as in Example 1, except that Step A and Step B were not performed, and single-walled CNT (Tuwall manufactured by OCSiAl) was used in Step C instead of the cloth-like CNT film. Layer c1 was obtained.

[Comparative Example 2]
Dispersion composition c2 and thermoelectric conversion were carried out in the same manner as in Example 2 except that Step A and Step B were not performed, and single-walled CNT (Tuwall manufactured by OCSiAl) was used in Step C instead of the cloth-like CNT film. Layer c2 was obtained.

[Comparative Example 3]
Dispersion composition was carried out in the same manner as in Example 3 except that Step A and Step B were not performed, and single-walled CNT (EC1.5 manufactured by Meijo Nanocarbon Co., Ltd.) was used instead of the cloth-like CNT film in Step C. c3 and a thermoelectric conversion layer c3 were obtained.

[Comparative Example 4]
In the same manner as in Example 4 except that Step A and Step B were not performed, and single-walled CNT (HP manufactured by KH Chemical Co.) was used instead of the cloth-like CNT film in Step C, the dispersion composition c4 and the thermoelectric A conversion layer c4 was obtained.

[Comparative Example 5]
Dispersion composition c5 and thermoelectric conversion were carried out in the same manner as in Example 16, except that Step A and Step B were not performed, and single-walled CNT (Tuwall manufactured by OCSiAl) was used in Step C instead of the cloth-like CNT film. Layer c5 was obtained.

[Comparative Example 6]
Dispersion composition c6 and thermoelectric conversion were carried out in the same manner as in Example 17 except that Step A and Step B were not performed, and single-walled CNT (Tuwall manufactured by OCSiAl) was used in Step C instead of the cloth-like CNT film. Layer c6 was obtained.

[Evaluation test]
The following evaluation tests were carried out using the dispersion compositions of the examples and comparative examples described above.

<Evaluation of elution from membrane>
Except for changing the size of the printed material formed on the polyimide to a 3 × 4 cm square size, the printed material corresponding to each example and comparative example is the same as the method for manufacturing the thermoelectric conversion layer in each of the above examples and comparative examples. Got. The weight before and after printing was measured, and the mass of the printed dispersion composition was calculated from the difference. The mass of the dispersant, the dopant, and the polymer compound in the printed material was calculated from the concentrations of the dispersant, the dopant, and the polymer compound in the dispersion composition.
The printed matter was dried at 50 ° C. for 30 minutes and 120 ° C. for 30 minutes, and then immersed in 50 mL of the solvent used in Step E in each Example and Comparative Example. After 1 hour, the membrane was removed.
Next, the mass of each component (dispersant, dopant, polymer compound) eluted from the printed material in the solvent used for the immersion treatment was determined by the following method. About the high molecular compound, the immersion liquid was analyzed by GPC, and it quantified from the analytical curve created separately. The dopant and dispersant were analyzed by reverse phase high performance liquid chromatography (corona charged particle detector) and quantified from a separately prepared calibration curve.
From the following formula, the elution degree from the film was calculated for the dispersant, the dopant, and the polymer compound.
Dispersion degree of dispersant = (mass of dispersant in immersion liquid) / (mass of dispersant in printed matter)
Dissolution rate of dopant = (mass of dopant in immersion liquid) / (mass of dopant in printed matter)
Elution degree of polymer compound = (mass of polymer compound in immersion liquid) / (mass of polymer compound in printed matter)
The elution degree from the membrane was calculated from the following formula and evaluated according to the following criteria.
Elution degree from membrane = (elution degree of dispersant) / (elution degree of dopant or polymer)
A: Elution degree from membrane is 10 or more B: Elution degree from membrane is more than 1 and less than 10 C: Elution degree from membrane is 1 or less

<Evaluation of dispersibility>
The dispersion composition of each Example and Comparative Example was placed on a mesh (400 mesh, manufactured by Niraco), and the residue on the mesh after sweeping three times with a urethane squeegee was observed and evaluated according to the following criteria.
A: Undispersed material was not observed on the mesh B: Undispersed material was slightly observed on the mesh C: Undispersed material was observed on the mesh

<Evaluation of conductivity and Seebeck coefficient>
Ten thermoelectric conversion layers corresponding to each of the examples and comparative examples were formed on polyimide in the same manner as in the method for manufacturing the thermoelectric conversion layer in each of the above examples and comparative examples. Conductivity and Seebeck at 80 ° C. and 105 ° C. using a thermoelectric property measuring device MODEL RZ2001i (manufactured by Ozawa Science Co., Ltd.) by cutting polyimide into 1 cm square along a 1 cm square thermoelectric conversion layer formed on polyimide. The coefficient was measured, and the conductivity and Seebeck coefficient at 100 ° C. were calculated by interpolation.
Ten thermoelectric conversion layers were subjected to the above measurement, and the average values of conductivity and Seebeck coefficient were calculated. Using the average value, the normalized conductivity and the normalized Seebeck coefficient were calculated from the following formula, and evaluated according to the following criteria.
Normalized conductivity = (average value of conductivity of each example / comparative example) / (average value of conductivity of reference comparative example)
AA: Normalized conductivity is 1.9 or more A: Normalized conductivity is 1.7 or more and less than 1.9 B: Normalized conductivity is 1.5 or more and less than 1.7 C: Normalized conductivity is 1.3 or more and less than 1.5 D: Normalized conductivity is 1.1 or more and less than 1.3 E: Normalized conductivity is less than 1.1 Standardized Seebeck coefficient = (Seebeck of each example and comparative example (Average value of coefficient) / (Average value of Seebeck coefficient of reference comparative example)
A: Normalized Seebeck coefficient is 1.1 or more B: Normalized Seebeck coefficient is 0.9 or more and less than 1.1 C: Normalized Seebeck coefficient is less than 0.9 In addition, the reference comparison of Example 1 and Comparative Example 1 As an example, Comparative Example 1 was used. Comparative Example 2 was used as a reference comparative example of Examples 2, 5-15, 18-20, and Comparative Example 2. Comparative Example 3 was used as a reference comparative example of Example 3 and Comparative Example 3. Comparative Example 4 was used as a reference comparative example of Example 4 and Comparative Example 4. Comparative Example 6 was used as a reference comparative example for Examples 16 and 17 and Comparative Example 6. Comparative Example 5 was used as a reference comparative example of Example 21 and Comparative Example 5.

<Evaluation of thermoelectric conversion performance index Z (performance index Z)>
Ten thermoelectric conversion layers of Examples and Comparative Examples obtained in the same manner as in the evaluation of the conductivity and Seebeck coefficient were prepared, and the thermoelectric conversion performance index Z was calculated and evaluated by the following method.
(Thermal conductivity)
Thermal conductivity was calculated by (specific heat) × (density) × (thermal diffusivity).
Specific heat was measured by DSC method, and density was measured from weight-dimension. The thermal diffusivity was measured using a thermal diffusivity measuring device ai-Phase Mobile 1u (manufactured by Eye Phase Co., Ltd.).
(Evaluation of thermoelectric conversion performance index Z)
Z was calculated for 10 films from [(conductivity) × (Seebeck coefficient) ² ] / thermal conductivity. Using the average value of Z, it was normalized by the following formula and evaluated according to the following criteria.
Normalized Z = (Z average value of each example / comparative example) / (Z average value of reference comparative example)
AA: Normalization Z is 3.0 or more A: Normalization Z is 2.5 or more and less than 3.0 B: Normalization Z is 2.0 or more and less than 2.5 C: Normalization Z is 1.5 or more Less than 2.0 D: Normalized Z is 1.1 or more and less than 1.5 E: Normalized Z is less than 1.1 Comparative Example 1 was used as a reference comparative example of Example 1 and Comparative Example 1. Comparative Example 2 was used as a reference comparative example of Examples 2, 5-15, 18-20, and Comparative Example 2. Comparative Example 3 was used as a reference comparative example of Example 3 and Comparative Example 3. Comparative Example 4 was used as a reference comparative example of Example 4 and Comparative Example 4. Comparative Example 6 was used as a reference comparative example for Examples 16 and 17 and Comparative Example 6. Comparative Example 5 was used as a reference comparative example of Example 21 and Comparative Example 5.

<Evaluation of variation in thermoelectric conversion performance>
In the evaluation of the thermoelectric conversion performance index Z, the difference between the maximum value and the minimum value was calculated for the thermoelectric conversion performance index Z of 10 thermoelectric conversion layers, normalized by the following formula, and evaluated according to the following criteria.
Variation of standardized Z = (difference between maximum value and minimum value of Z in each example / comparative example) / (difference between maximum value and minimum value of Z in reference comparative example)
A: Variation of standardized Z is 0.5 or less B: Variation of standardized Z is more than 0.5 and less than 0.9 C: Variation of standardized Z is 0.9 or more Standard of Example 1 and Comparative Example 1 Comparative Example 1 was used as a comparative example. Comparative Example 2 was used as a reference comparative example of Examples 2, 5-15, 18-20, and Comparative Example 2. Comparative Example 3 was used as a reference comparative example of Example 3 and Comparative Example 3. Comparative Example 4 was used as a reference comparative example of Example 4 and Comparative Example 4. Comparative Example 6 was used as a reference comparative example for Examples 16 and 17 and Comparative Example 6. Comparative Example 5 was used as a reference comparative example of Example 21 and Comparative Example 5.

<Evaluation results>
The results of the above evaluation tests are shown in Table 1. The polarities of the thermoelectric conversion layers of Examples and Comparative Examples are also shown in Table 1.

As shown in the evaluation results of Table 1, all of the dispersion compositions of Examples were excellent in carbon nanotube dispersibility. In addition, each of the thermoelectric conversion layers obtained using the dispersion compositions of the examples is superior in electrical conductivity and figure of merit Z compared to the thermoelectric conversion layers of the comparative examples, and variation in thermoelectric conversion performance is also reduced. I found out.
In comparison with Example 2 and Example 5, when a dispersion composition containing a dopant is used (Example 5), the conductivity and thermoelectric conversion performance index Z of the resulting thermoelectric conversion layer will be more excellent. It has been shown. A similar tendency was shown from the comparison between Example 8 and Example 9.
Comparison between Example 2 and Example 6 shows that when a dispersion composition containing a polymer compound is used, the conductivity and thermoelectric conversion performance index Z of the resulting thermoelectric conversion layer are improved. It was. The same tendency was shown from the comparison between Example 8 and Example 10 and the comparison between Example 14 and Example 15.
In comparison with Example 2 and Example 18, when a dispersion composition containing an antifoaming agent was used (Example 18), the conductivity and thermoelectric conversion performance index Z of the resulting thermoelectric conversion layer were improved. It was shown to be. The same tendency was shown from the comparison between Example 7 and Example 19 and the comparison between Example 15 and Example 20.
Although not shown in the table, when Example 2 and Example 21 were compared, the Seebeck coefficient of the thermoelectric conversion layer obtained by performing Step E (cleaning step) (Example 2), It turned out that the value of electrical conductivity and the thermoelectric conversion performance index Z is more excellent.

On the other hand, it was shown that all of the dispersion compositions of Comparative Examples 1 to 5 have insufficient carbon nanotube dispersibility.
Moreover, the thermoelectric conversion layer obtained using the dispersion composition of Comparative Examples 1-6 showed that the dispersion | variation in thermoelectric conversion performance was large, and the thermoelectric conversion performance index Z and electrical conductivity were also inadequate.

110, 120 Thermoelectric conversion element 12, 22 First base material 13, 23 First electrode 15, 25 Second electrode 14, 24 Thermoelectric conversion layer

Claims (21)

A step A in which a carbon nanotube and an organic solvent are mixed to obtain a coarse dispersion composition;
Step B for obtaining a carbon nanotube film using the coarse dispersion composition;
A step of obtaining a dispersion composition by mixing a dispersant, a solvent A, and 1% w / v or more of the carbon nanotube film-like material with respect to the solvent A;
A method for producing a dispersion composition comprising:   The manufacturing method of the dispersion composition of Claim 1 which further adds a dopant in the said process C.   The manufacturing method of the dispersion composition of Claim 1 or 2 which adds a high molecular compound in the said process C further.   The manufacturing method of the dispersion composition of any one of Claims 1-3 whose ClogP value of the said solvent A is -0.5 or less.   The manufacturing method of the dispersion composition of any one of Claims 1-4 whose said solvent A is water.   The manufacturing method of the dispersion composition of any one of Claims 1-5 whose said dispersing agent is surfactant.   In the said process A, the manufacturing method of the dispersion composition of any one of Claims 1-6 which mixes with a homogenizer.   In the said process C, the manufacturing method of the dispersion composition of any one of Claims 1-7 which mixes by a thin film turning method.   The manufacturing method of the dispersion composition of any one of Claims 1-8 in which the said carbon nanotube contains a single wall carbon nanotube.   The manufacturing method of the dispersion composition of any one of Claims 1-9 used for formation of a thermoelectric conversion layer. A step A in which a carbon nanotube and an organic solvent are mixed to obtain a coarse dispersion composition;
Step B for obtaining a carbon nanotube film using the coarse dispersion composition;
A step of obtaining a dispersion composition by mixing a dispersant, a solvent A, and 1% w / v or more of the carbon nanotube film-like material with respect to the solvent A;
Step D for obtaining a thermoelectric conversion layer using the dispersion composition;
A method for producing a thermoelectric conversion layer. In step C, a dopant is further added,
12. The method according to claim 11, further comprising a step E of cleaning the thermoelectric conversion layer using a solvent B1 having an elution degree of the dispersant from the thermoelectric conversion layer higher than that of the dopant after the step D. The manufacturing method of the thermoelectric conversion layer of description. In the step C, a polymer compound is further added,
After the step D, the method further comprises a step E of washing the thermoelectric conversion layer using a solvent B2 in which the elution degree of the dispersant from the thermoelectric conversion layer is higher than the elution degree of the polymer compound. The manufacturing method of the thermoelectric conversion layer of the thermoelectric conversion layer of Claim 11. In step C, a dopant and a polymer compound are further added,
After the step D, a step E of washing the thermoelectric conversion layer using a solvent B3 in which the elution degree of the dispersant from the thermoelectric conversion layer is higher than any elution degree of the dopant and the polymer compound. Furthermore, the manufacturing method of the thermoelectric conversion layer of Claim 11 which has.   The manufacturing method of the thermoelectric conversion layer of any one of Claims 11-14 which adds an antifoamer in the said process C further.   The manufacturing method of the thermoelectric conversion layer of any one of Claims 11-15 whose ClogP value of the said solvent A is -0.5 or less.   The method for producing a thermoelectric conversion layer according to any one of claims 11 to 16, wherein the solvent A is water.   The method for producing a thermoelectric conversion layer according to any one of claims 11 to 17, wherein the dispersant is a surfactant.   The method for producing a thermoelectric conversion layer according to any one of claims 11 to 18, wherein in the step A, mixing is performed by a homogenizer.   The method of manufacturing a thermoelectric conversion layer according to any one of claims 11 to 19, wherein in the step C, mixing is performed by a thin film swirl method.   The manufacturing method of the thermoelectric conversion layer of any one of Claims 11-20 in which the said carbon nanotube contains a single-walled carbon nanotube.

Images