JPWO2017122808A1 - Method for producing film for thermoelectric conversion element - Google Patents

Abstract

An object of this invention is to provide the film for thermoelectric conversion elements which can ensure the film self-supporting property and can exhibit the thermoelectric conversion characteristic sufficiently excellent in the thermoelectric conversion element. The method for producing a film for a thermoelectric conversion element of the present invention comprises a step of forming a pre-treatment film using a pre-treatment film composition comprising carbon nanotubes, an insulating polymer material, and a conductive material, and the treatment And a step of bringing a pre-film into contact with a treatment liquid to obtain a film for a thermoelectric conversion element, wherein the density of the pre-treatment film is DB (g / cm 3) and the density of the thermoelectric conversion element film is DA (g / cm 3). ), The DA / DB value is more than 0.5 and less than 0.9.

Description

  The present invention relates to a method for producing a thermoelectric conversion element film.

  2. Description of the Related Art Conventionally, thermoelectric conversion elements that can directly convert thermal energy into electrical energy have attracted attention. Here, in the thermoelectric conversion element, an inorganic material has been used for the preparation of the thermoelectric conversion material layer responsible for the energy conversion. However, in recent years, from the viewpoint of excellent workability and flexibility, a technique for preparing a thermoelectric conversion material layer of a thermoelectric conversion element using an organic material including a polymer material has been studied.

  For example, Patent Document 1 describes that a film obtained from a resin composition containing an insulating resin, an inorganic thermoelectric conversion material, and a charge transport material is used for the thermoelectric conversion material layer. And according to patent document 1, the electrical conductivity of a film can be improved by making the said film contact with a specific kind of process liquid.

Japanese Patent Laying-Open No. 2015-170766

  However, in the above conventional technique, there is a problem that when the film is brought into contact with a specific processing solution in order to improve the conductivity, the film self-supporting property of the film is impaired, and the thermoelectric conversion element sufficiently excellent for the thermoelectric conversion element. In some cases, it was difficult to exhibit the characteristics. That is, the above-described conventional technique has room for improvement in that the thermoelectric conversion element exhibits more excellent thermoelectric conversion characteristics while maintaining the film self-supporting property of the film for the thermoelectric conversion element formed using the organic material. was there.

  The present inventors have intensively studied to achieve the above object. The present inventors then developed a pre-treatment film formed from a composition containing carbon nanotubes (hereinafter sometimes referred to as “CNT”), an insulating polymer material, and a conductive material, before and after contact. If the film for a thermoelectric conversion element is formed by contacting the treatment liquid so that the change is within a predetermined range, the film self-supporting property of the film can be maintained, and in addition, the film can be used as a thermoelectric conversion material layer. Thus, the present inventors have found that the thermoelectric conversion element can exhibit sufficiently excellent thermoelectric conversion characteristics, and completed the present invention.

That is, this invention aims at solving the said subject advantageously, and the manufacturing method of the film for thermoelectric conversion elements of this invention is a carbon nanotube, an insulating polymer material, a conductive material, And a step of forming a pre-treatment film using a composition for pre-treatment film, and a step of bringing the pre-treatment film into contact with a treatment liquid to obtain a film for a thermoelectric conversion element, and the density of the pre-treatment film Is D _B (g / cm ³ ), and the density of the thermoelectric conversion element film is D _A (g / cm ³ ), the value of D _A / D _B is more than 0.5 and less than 0.9. It is characterized by that. Thus, the film self-sustainability is ensured for the film for thermoelectric conversion elements obtained by contacting the treatment liquid so that the density change before and after the contact is within a predetermined range. In addition, if the thermoelectric conversion element film is used as a thermoelectric conversion material layer, the thermoelectric conversion element can exhibit sufficiently excellent thermoelectric conversion characteristics.

  Here, in the method for producing a film for a thermoelectric conversion element of the present invention, the conductive material includes a salt of poly (M 1,1,2,2-ethenetetrathiolate) [wherein M represents a metal]. It is preferable. This is because if the salt of poly (M 1,1,2,2-ethenetetrathiolate) is used as the conductive material, the thermoelectric conversion characteristics of the thermoelectric conversion element can be further improved.

  And in the manufacturing method of the film for thermoelectric conversion elements of this invention, it is preferable that the said insulating polymer material contains a polyimide resin. This is because if a polyimide resin is used as the insulating polymer material, the film self-sustaining property of the thermoelectric conversion element film and the thermoelectric conversion characteristics of the thermoelectric conversion element can be further improved.

Furthermore, in the manufacturing method of the film for thermoelectric conversion elements of this invention, it is preferable that the specific surface area of the said carbon nanotube is 600 m < ² > / g or more. This is because if the CNT having a specific surface area of 600 m ² / g or more is used, the thermoelectric conversion characteristics of the thermoelectric conversion element can be further improved.

  Moreover, in the manufacturing method of the film for thermoelectric conversion elements of this invention, it is preferable that the said process liquid contains N-methyl-2- pyrrolidone. This is because if N-methyl-2-pyrrolidone is used as the treatment liquid, the production efficiency of the thermoelectric conversion element film can be increased and the thermoelectric conversion characteristics of the thermoelectric conversion element can be further improved.

  According to the method for producing a film for a thermoelectric conversion element of the present invention, it is possible to provide a film for a thermoelectric conversion element that can ensure film self-sustainability and can exhibit sufficiently excellent thermoelectric conversion characteristics.

  Hereinafter, embodiments of the present invention will be described in detail. The manufacturing method of the film for thermoelectric conversion elements of this invention is used for manufacture of the film for thermoelectric conversion elements used as the thermoelectric conversion material layer of a thermoelectric conversion element.

(Method for producing thermoelectric conversion element film)
The method for producing a film for a thermoelectric conversion element of the present invention comprises a pre-treatment film using a pre-treatment film composition containing carbon nanotubes, an insulating polymer material, and a conductive material, and optionally containing other components. And a step of forming (a pre-treatment film forming step) and a step of bringing the pre-treatment film into contact with the treatment liquid to obtain a thermoelectric conversion element film (treatment liquid contact step). Then, in the treatment solution contact step, the density of the pretreatment film ^{_{D B (g / cm 3)}} , if the density of the thermoelectric conversion element film was ^{_{D A (g / cm 3)}} , the D A / _{D B} It is necessary to be more than 0.5 and less than 0.9. The film for thermoelectric conversion elements obtained by using the production method of the present invention can be used as a self-supporting film. And if the said film for thermoelectric conversion elements is used as a thermoelectric conversion material layer, the thermoelectric conversion characteristic sufficiently excellent in the thermoelectric conversion element can be exhibited.
In addition, the reason why the film for thermoelectric conversion elements capable of improving the thermoelectric conversion characteristics of the thermoelectric conversion element while securing film self-sustainability by using the method for manufacturing a film for thermoelectric conversion element of the present invention is as follows. It is guessed as follows. First, when D _A / D _B is less than 0.9, surplus insulating polymer material and / or conductive material is eluted in the treatment liquid, reducing the density of the film, and voids in the film The part can be increased. Therefore, it is thought that the thermal conductivity of the film for thermoelectric conversion elements is lowered and the thermoelectric conversion characteristics can be improved. On the other hand, since D _A / D _B is more than 0.5, excessive elution of the insulating polymer material, which is a matrix resin, into the processing solution is suppressed, so that the strength that can be used as a self-supporting film is sufficient. Can be secured.

<Film forming process before treatment>
First, the film before a process is manufactured using the composition for a film before a process.

[Composition for film before treatment]
The composition for pre-treatment film for forming the pre-treatment film is usually formed by dispersing and / or dissolving CNT, an insulating polymer material, a conductive material, and other optional components in a solvent. Use the composition.

[[carbon nanotube]]
The CNT contained in the pre-treatment film composition may be a single-walled carbon nanotube or a multi-walled carbon nanotube, but from the viewpoint of further improving the thermoelectric conversion characteristics of the thermoelectric conversion element, It is preferable to include at least one of double-walled carbon nanotubes, and it is preferable to include single-walled carbon nanotubes.

Here, the average diameter of the CNTs is preferably 0.5 nm or more, and more preferably 1 nm or more. If the average diameter of CNT is 0.5 nm or more, aggregation of CNT can be suppressed and the thermoelectric conversion characteristics of the thermoelectric conversion element can be further enhanced. Moreover, the upper limit of the average diameter of CNT is not particularly limited, but is, for example, 15 nm or less.
In addition, the average diameter of CNT can be calculated | required by measuring the diameter of 100 carbon nanotubes selected at random using the transmission electron microscope.

Further, the average length of CNT is preferably 0.1 μm or more, preferably 1 cm or less, and more preferably 3 mm or less. When the average length of the CNT is within the above range, the thermoelectric conversion characteristics of the thermoelectric conversion element can be further enhanced.
In addition, the average length of CNT can be calculated | required by measuring the length of 100 carbon nanotubes selected at random using the transmission electron microscope.

Then, as the BET specific surface area of the CNT, preferably at 600 meters ² / g or more, more preferably 800 m ² / g or more, is preferably from ^{2600m 2 / g, 1200m 2 /} g or less More preferably. When the BET specific surface area of the CNT is within the above range, the thermoelectric conversion characteristics of the thermoelectric conversion element can be further enhanced.
The “BET specific surface area” of CNT can be determined by measuring the nitrogen adsorption isotherm at 77K and using the BET method. Here, for the measurement of the BET specific surface area, for example, “BELSORP (registered trademark) -max” (manufactured by Nippon Bell Co., Ltd.) can be used.

  The method for producing CNTs used in the present invention is not particularly limited, but is a method by catalytic hydrogen reduction of carbon dioxide, arc discharge method, chemical vapor deposition method (CVD method), laser evaporation method, vapor phase growth method. Method, gas phase flow method, HiPCO method and the like. Among them, the CNT having the preferable properties described above is used, for example, when a raw material compound and a carrier gas are supplied onto a substrate having a catalyst layer for producing carbon nanotubes on the surface, and the CNT is synthesized by a CVD method. By producing a small amount of oxidant (catalyst activating substance) in the inside, the catalyst activity of the catalyst layer is dramatically improved (super growth method; see WO 2006/011655). can do. Hereinafter, the carbon nanotube obtained by the super growth method may be referred to as “SGCNT”.

  In addition, the CNT may have a functional group such as a carboxyl group introduced therein. The introduction of the functional group can be performed by a known method such as an oxidation treatment method using hydrogen peroxide, nitric acid or the like, or a contact treatment method with a supercritical fluid, a subcritical fluid, or a high-temperature high-pressure fluid.

[[Insulating polymer material]]
The insulating polymer material contained in the pre-treatment film composition is an insulating polymer material that can withstand the operating temperature of the thermoelectric conversion element while imparting flexibility to the resulting film for thermoelectric conversion element. If there is no particular limitation. Here, that the polymer material has “insulation” means that the conductivity of the polymer material is 1 S · cm ⁻¹ or less. The thermal conductivity of the insulating polymer material is preferably 0.5 W · m ⁻¹ K ⁻¹ or less, and more preferably 0.4 W · m ⁻¹ K ⁻¹ or less. The insulating polymer material preferably has binding properties.
Here, the electrical conductivity of the polymer material is determined by, for example, “Loresta (registered trademark) -GP (MCP-T600 type)” after forming a thin film of the polymer material and measuring the film thickness. Measured with a resistivity meter such as Mitsubishi Chemical Analytech Co., Ltd., and can be determined from the measured film thickness and surface resistivity. In addition, the thermal conductivity (к) of the polymer material has a thermal diffusivity α (mm ² · S ⁻¹ , 25 ° C.), a specific heat Cp (J · g ⁻¹ K ⁻¹ , 25 ° C.) and a density ρ (g・ Cm ⁻³ ) and can be calculated using the following formula.
к = α × Cp × ρ
Here, the thermal diffusivity α, the specific heat Cp, and the density ρ in the formula can be measured by the following apparatus and method.
α: Nano Flash Analyzer (manufactured by Netch Japan, LFA 447 / 2-4 / InSb NanoFlash Xe)
Cp: Differential scanning calorimeter (Netch Japan, DSC 204 F1 Phoenix)
ρ: Archimedes method

Here, examples of the insulating polymer material include polypropylene, high density polyethylene, low density polyethylene, linear low density polyethylene, crosslinked polyethylene, ultrahigh molecular weight polyethylene, polybutene-1, poly-3-methylpentene, poly- Polyolefins such as 4-methylpentene, polycycloolefin, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene-propylene copolymer, copolymer of polyethylene and cycloolefin (norbornene, etc.); Vinyl chloride, polyvinylidene chloride, chlorinated polyethylene, chlorinated polypropylene, polyvinylidene fluoride, rubber chloride, vinyl chloride-vinyl acetate copolymer, vinyl chloride-ethylene copolymer, vinyl chloride-vinylidene chloride copolymer, vinyl chloride -Vinylidene chloride-vinegar Halogenated polyolefins such as vinyl terpolymer, vinyl chloride-acrylic acid ester copolymer, vinyl chloride-maleic acid ester copolymer, vinyl chloride-cyclohexyl maleimide copolymer; petroleum resin; coumarone resin; polystyrene; Vinyl acetate; acrylic resin such as polymethyl methacrylate; polyacrylonitrile; AS resin, ABS resin, ACS resin, SBS resin, MBS resin, heat-resistant ABS resin and other styrenic resins; polyvinyl alcohol; polyvinyl formal; polyvinyl butyral; polyethylene terephthalate; Polyalkylene terephthalates such as polytrimethylene terephthalate, polybutylene terephthalate, polycyclohexanedimethylene terephthalate; polyethylene naphthalate, polybutylene naphthalate A polyalkylene naphthalate; a liquid crystal polyester (LCP); a polyhydroxybutyrate, polycaprolactone, polybutylene succinate, polyethylene succinate, polylactic acid, polymalic acid, polyglycolic acid, polydioxane, poly (2-oxetanone), etc. Degradable aliphatic polyester; polyphenylene oxide; nylon 6, nylon 11, nylon 12, nylon 6,6, nylon 6,10, nylon 6T, nylon 6I, nylon 9T, nylon M5T, nylon 6,12, nylon MXD6, para series Nylon resins such as aramid and meta-aramid; polycarbonate resin; polyacetal resin; polyphenylene sulfide; polyurethane; polyimide resin; polyamideimide resin; Examples include ruthetone ketone resin; arabic rubber; cellulose acetate. These may be used alone or in combination of two or more.
Of these insulating polymer materials, polyimide resin is preferable. Polyimide resin is excellent in temperature resistance, mechanical strength, insulation, and chemical stability, and has low moisture permeability and linear expansion coefficient. Therefore, if a polyimide resin is used, the thermoelectric conversion element can exhibit more excellent thermoelectric conversion characteristics while having sufficient film self-supporting properties, and a thermoelectric conversion element film suitable for actual use can be obtained.

  The blending amount of the insulating polymer material in the pre-treatment film composition is not particularly limited, but is preferably 30 parts by mass or more, more preferably 50 parts by mass or more per 100 parts by mass of CNTs, 120 More preferably, it is more preferably 150 parts by mass or more, more preferably 500 parts by mass or less, more preferably 400 parts by mass or less, and more preferably 350 parts by mass or less. More preferably, it is particularly preferably 300 parts by mass or less. If the blending amount of the insulating polymer material is within the above range, the film self-supporting property of the thermoelectric conversion element film and the thermoelectric conversion characteristics of the thermoelectric conversion device can be further enhanced.

[[Conductive material]]
The conductive material contained in the pre-treatment film composition is a substance that transports electrons or holes or promotes their transport. By using a conductive material, the conductivity of the obtained film for thermoelectric conversion elements can be ensured. In the present invention, “carbon nanotube” and “insulating polymer material” are not included in “conductive material”.

  And as a conductive material, the substance currently used in order to accelerate | stimulate transport of an electron or a hole can be used in various uses. For example, a charge transport material used as a constituent material of an organic electroluminescence element, a constituent material of a photoelectric conversion element, or a constituent material of a photosensitive layer provided in an electrophotographic photosensitive member used in an electrophotographic apparatus is used as a conductive material. It can be preferably used.

式中、Ｍは金属原子を表し、例えばＮｉ、Ｃｕ、Ｐｄ、Ｃｏ、Ｆｅの何れかを表す。そしてＡ^＋は１価又は２価の陽イオンを表し、例えばＮａ^＋、Ｋ^＋、Ｃｕ^２＋、ＮＲ_４ ^＋［Ｒは水素原子又はアルキル基を表し、４つのＲのうち少なくとも１つのＲはアルキル基である。なおアルキル基の水素原子は任意の官能基に置換されていてもよい。］の何れかを表す。Ｘは繰り返し単位当たりのＡ^＋の数を表し、例えば１以上３以下の整数を表す。そして、ｎは繰り返し単位の数を表し、例えば３以上１００００以下の整数を表す。
なお、上記ポリ（Ｍ １,１,２,２−エテンテトラチオラート）の塩は、例えば「“Organic thermoelectric materials and devices based on p- and n-type poly(metal 1,1,2,2-ethenetetrathiolate)s”，Yimeng Sun, Peng Sheng, Chongan Di, Fei Jiao, Wei Xu,Dong Qiu, and Daoben Zhu, Advanced Materials, 2012, vol.24, p.932-937」にその詳細が開示されている。Here, preferable examples of the conductive material include N, N, N ′, N′-tetraphenyl-4,4′-diaminophenyl, N, N′-diphenyl-N, N′-bis (3-methyl Phenyl)-[1,1′-biphenyl] -4,4′-diamine (TPD), 2,2-bis (4-di-p-tolylaminophenyl) propane, 1,1-bis (4-di-) p-tolylaminophenyl) cyclohexane, N, N, N ′, N′-tetra-p-tolyl-4,4′-diaminobiphenyl, 1,1-bis (4-di-p-tolylaminophenyl) -4 -Phenylcyclohexane, bis (4-dimethylamino-2-methylphenyl) phenylmethane, bis (4-di-p-tolylaminophenyl) phenylmethane, N, N'-diphenyl-N, N'-di (4- Methoxyphenyl) -4,4'-diamy Nobiphenyl, N, N, N ′, N′-tetraphenyl-4,4′-diaminodiphenyl ether, 4,4′-bis (diphenylamino) quadriphenyl, N, N, N-tri (p-tolyl) Amine, 4- (di-p-tolylamino) -4 ′-[4- (di-p-tolylamino) styryl] stilbene; 4-N, N-diphenylamino- (2-diphenylvinyl) benzene; 3-methoxy- 4′-N, N-diphenylaminostilbenzene, N-phenylcarbazole, 4,4′-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (NPD), and 4,4 ′, 4 ″ -Aromatic amine compounds such as tris [N- (3-methylphenyl) -N-phenylamino] triphenylamine (MTDATA); anthracene, tetracene, pentacene, hexene Sen, heptacene, chrysene, picene, fluorene, pyrene, peropyrene, perylene, terylene, quaterylene, coronene, ovalen, circumcamanthracene, bisanthene, zeslen, heptazeslen, pyranthrene, violanthene, isoviolanthene, sacobiphenyl, and anthradithiophene And condensed polycyclic aromatic compounds such as derivatives thereof; conjugated compounds such as tetrathiafulvalene compounds, quinone compounds, and cyano compounds such as tetracyanoquinodimethane; tetrathiafulvalene-tetracyanoquinodimethane complexes, polymers And a salt of poly (M 1,1,2,2-ethenetetrathiolate) which is a salt of a metal complex, wherein M in the polymer metal complex represents a metal, and M is, for example, nickel , Copper, palladium, koval , It includes the iron. Examples of the salt include sodium salts, potassium salts, copper salts, and alkylammonium salts (including those in which a hydrogen atom of an alkyl group is substituted with an arbitrary functional group).
The salt of poly (M 1,1,2,2-ethenetetrathiolate) specifically has the structure of the following formula (I)

In the formula, M represents a metal atom, for example, any one of Ni, Cu, Pd, Co, and Fe. A ⁺ represents a monovalent or divalent cation, for example, Na ⁺ , K ⁺ , Cu ²⁺ , NR ₄ ⁺ [R represents a hydrogen atom or an alkyl group, and at least one of four R is an alkyl It is a group. The hydrogen atom of the alkyl group may be substituted with any functional group. ] Is represented. X represents the number of A ⁺ per repeating unit, for example, an integer of 1 or more and 3 or less. N represents the number of repeating units, for example, an integer of 3 to 10,000.
The salt of poly (M 1,1,2,2-ethenetetrathiolate) is, for example, ““ Organic thermoelectric materials and devices based on p- and n-type poly (metal 1,1,2,2-ethenetetrathiolate ”. ) s ”, Yimeng Sun, Peng Sheng, Chongan Di, Fei Jiao, Wei Xu, Dong Qiu, and Daoben Zhu, Advanced Materials, 2012, vol.24, p.932-937.

  These conductive materials may be used alone or in combination of two or more. Among these conductive materials, a salt of poly (M 1,1,2,2-ethenetetrathiolate) is preferable from the viewpoint of further improving the thermoelectric conversion characteristics of the thermoelectric conversion element. The salt of poly (M 1,1,2,2-ethenetetrathiolate) is, for example, ““ Novel Nanodispersed Polymer Complex, Poly (nickel 1,1,2,2-ethenetetrathilate): Preparation and Hybridization for n- Refer to “Type of Organic Thermoelectric Materials”, Keisuke Oshima, Yukihide Shiraishi, and Naoki Toshima, Chemistry Letters, 2015, Vol.44, No.9, p.1185-1187, and use dodecyltrimethylammonium bromide (DTAB) It is preferable to use it after making it into nanoparticles and dispersing and solubilizing it.

  Although the compounding quantity of the electroconductive material in the composition for a film before a process is not specifically limited, It is preferable that it is 30 mass parts or more per 100 mass parts of CNT, It is more preferable that it is 50 mass parts or more, 120 mass parts More preferably, it is more preferably 150 parts by mass or more, preferably 500 parts by mass or less, more preferably 400 parts by mass or less, and further preferably 350 parts by mass or less. 320 parts by mass or less is particularly preferable. When the blending amount of the conductive material is within the above range, it is possible to improve the conductivity of the thermoelectric conversion element film and further improve the thermoelectric conversion characteristics of the thermoelectric conversion element.

[[solvent]]
The solvent that can be used in the pre-treatment film composition is not particularly limited as long as it can dissolve and / or disperse CNTs, insulating polymer materials, and conductive materials. As the solvent, an organic solvent is preferable, and specifically, organic solvents listed in the section of “treatment liquid” described later can be used. A solvent may be used individually by 1 type and may be used in combination of 2 or more type. Among these, N-methyl-2-pyrrolidone, N, N-dimethylformamide, and dimethyl sulfoxide are preferable, and N-methyl-2-pyrrolidone is more preferable from the viewpoint of improving the dispersibility of CNT.
In addition, the kind and compounding quantity of the solvent in the composition for a film before a process can be suitably adjusted according to kind and quantity, such as CNT, an insulating polymer material, and an electroconductive material.

[[Other ingredients]]
The composition for pre-treatment film may contain components other than the above-mentioned CNT, insulating polymer material, conductive material, and solvent. Examples of such other components include, but are not limited to, carbon nanotube dispersants, triphenylphosphine, cellulose, known inorganic thermoelectric conversion materials used for thermoelectric conversion material layers, and the like.
Examples of the carbon nanotube dispersant include surfactants such as sodium dodecylsulfonate, sodium deoxycholate, sodium cholate, sodium dodecylbenzenesulfonate.
Moreover, it does not specifically limit as an inorganic thermoelectric conversion material, However, The thing of Unexamined-Japanese-Patent No. 2015-170766 is mentioned.
The compounding quantity of these other components can be adjusted suitably.

[[Preparation of pre-treatment film composition]]
The composition for pre-treatment film can be prepared by mixing the above-described components by a known method. However, a crude mixture containing CNT, an insulating polymer material, a conductive material, and a solvent is used as a cavitation effect or It is preferable to manufacture through the process of mixing by the dispersion process from which a crushing effect is acquired. If a pre-treatment film composition is prepared using a dispersion treatment that provides a cavitation effect or a dispersion treatment that provides a crushing effect, the CNTs are well dispersed and the thermoelectric conversion element has sufficient excellent thermoelectric conversion characteristics. It is because it can be demonstrated.

-Distributed processing with cavitation effect-
The dispersion treatment that provides a cavitation effect is a dispersion method that uses a shock wave that is generated when a vacuum bubble generated in a solvent bursts when high energy is applied to a liquid. By using this dispersion method, CNTs can be dispersed well.

  Here, specific examples of the dispersion treatment that can provide a cavitation effect include dispersion treatment using ultrasonic waves, dispersion treatment using a jet mill, and dispersion treatment using high shear stirring. Only one of these distributed processes may be performed, or a plurality of distributed processes may be combined. More specifically, for example, an ultrasonic homogenizer, a jet mill, and a high shear stirring device are preferably used. These devices may be conventionally known devices.

  When an ultrasonic homogenizer is used, ultrasonic waves may be applied to the coarse dispersion using an ultrasonic homogenizer. What is necessary is just to set suitably for the time to irradiate according to the quantity of CNT, etc. For example, 1 minute or more is preferable, 5 minutes or more are more preferable, 5 hours or less are preferable, and 2 hours or less are more preferable. The output is preferably 10 W or more and 50 W or less, and the temperature is preferably 0 ° C. or more and 50 ° C. or less.

  In the case of using a jet mill, the number of treatments may be appropriately set depending on the amount of CNT, etc., for example, preferably 2 times or more, more preferably 5 times or more, preferably 100 times or less, more preferably 50 times or less. . For example, the pressure is preferably 20 MPa or more and 250 MPa or less, and the temperature is preferably 15 ° C. or more and 50 ° C. or less.

  Furthermore, when high shear stirring is used, stirring and shearing may be applied to the coarse dispersion by a high shear stirring device. The faster the turning speed, the better. For example, the operation time (time during which the machine is rotating) is preferably 3 minutes or more and 4 hours or less, the peripheral speed is preferably 5 m / second or more and 50 m / second or less, and the temperature is preferably 15 ° C. or more and 50 ° C. or less.

  In addition, it is more preferable to perform the dispersion treatment for obtaining the above-described cavitation effect at a temperature of 50 ° C. or lower. This is because a change in concentration due to the volatilization of the solvent is suppressed.

-Dispersion treatment that provides the effect of crushing-
Dispersion treatment with a crushing effect can not only uniformly disperse CNTs in a solvent, but also suppress damage to CNTs due to shock waves when bubbles disappear, compared to the dispersion treatment with the above-mentioned cavitation effect. It is more advantageous in that it can be done.

In the dispersion treatment in which this crushing effect is obtained, a shearing force is applied to the coarse dispersion to crush and disperse the CNT aggregates, and further, a back pressure is applied to the coarse dispersion. By cooling the CNTs, the CNTs can be uniformly dispersed in the solvent while suppressing the generation of bubbles.
When a back pressure is applied to the coarse dispersion, the back pressure applied to the coarse dispersion may be reduced to atmospheric pressure all at once, but is preferably reduced in multiple stages.

Here, in order to further disperse the CNTs by applying a shearing force to the coarse dispersion, for example, a dispersion system having a disperser having the following structure may be used.
In other words, the disperser has a disperser orifice having an inner diameter d1, a dispersion space having an inner diameter d2, and a terminal portion having an inner diameter d3 from the inflow side to the outflow side of the coarse dispersion liquid (where d2>d3> d1)).
In this disperser, the inflowing high-pressure (for example, 10 to 400 MPa, preferably 50 to 250 MPa) coarse dispersion passes through the disperser orifice, and becomes a high flow rate fluid with a decrease in pressure. Into the dispersed space. Thereafter, the high-velocity coarse dispersion liquid flowing into the dispersion space flows at high speed in the dispersion space and receives a shearing force at that time. As a result, the flow rate of the coarse dispersion decreases and CNTs are well dispersed. And the fluid of the pressure (back pressure) lower than the pressure of the inflowing coarse dispersion liquid flows out from the terminal part as the composition for pre-treatment film.

Note that the back pressure of the coarse dispersion can be applied to the coarse dispersion by applying a load to the flow of the coarse dispersion. For example, a rough pressure can be obtained by disposing a multistage step-down device downstream of the disperser. A desired back pressure can be applied to the dispersion.
Then, by reducing the back pressure of the coarse dispersion in multiple stages using a multistage pressure reducer, bubbles are generated in the film composition before processing when the film composition before processing is finally released to atmospheric pressure. Can be suppressed.

Further, the disperser may include a heat exchanger for cooling the coarse dispersion and a cooling liquid supply mechanism. This is because the generation of bubbles in the coarse dispersion can be further suppressed by cooling the coarse dispersion that has been heated to a high temperature by applying a shearing force with the disperser.
In addition, it can suppress that a bubble generate | occur | produces in the solvent containing CNT also by cooling a rough dispersion liquid beforehand instead of arrangement | positioning of a heat exchanger etc.

  As described above, in the dispersion treatment in which this crushing effect is obtained, since the occurrence of cavitation can be suppressed, damage to CNT caused by cavitation that is sometimes a concern, in particular, CNT caused by shock waves when bubbles disappear. Damage can be suppressed. In addition, it is possible to uniformly and efficiently disperse CNTs by suppressing the adhesion of bubbles to the CNTs and energy loss due to the generation of bubbles.

  As a distributed system having the above configuration, for example, there is a product name “BERYU SYSTEM PRO” (manufactured by Miki Co., Ltd.). And the dispersion | distribution process from which a crushing effect is acquired can be implemented by controlling a dispersion | distribution condition appropriately using such a dispersion | distribution system.

[Formation of film before treatment]
The pre-treatment film can be formed by removing at least a part of the solvent from the pre-treatment film composition described above. For example, after supplying the pre-treatment film composition onto the substrate by coating or casting, the solvent is removed from the film of the pre-treatment film composition formed on the base material, thereby removing the pre-treatment film. Can be manufactured.
And as a base material which apply | coats a film before a process, a known thing is mentioned, For example, the thing of Unexamined-Japanese-Patent No. 2014-199837 can be used.
Moreover, the method of removing a solvent from the film of the composition for film before a process is not specifically limited, The method of heating the said film, the method of putting the said film in a pressure-reduced atmosphere under room temperature or heating, etc. are mentioned. These conditions can be set as appropriate.
In addition, although the thickness of the film before a process is not specifically limited, 0.1 micrometer or more and 100 micrometers or less are preferable from a viewpoint of ensuring the film | membrane self-supporting property of the film for thermoelectric conversion elements obtained in the process liquid contact process.

<Processing liquid contact process>
Next, the pre-treatment film obtained through the above-mentioned pre-treatment film formation step is brought into contact with the treatment liquid.

[Treatment solution]
The treatment liquid is not particularly limited as long as it can penetrate the pre-treatment film and dissolve and remove excess insulating polymer material and / or conductive material. As the treatment liquid, for example, an organic solvent is preferable. Preferable examples of the organic solvent used as the treatment liquid include aromatic solvents such as toluene, xylene, ethylbenzene, anisole, trimethylbenzene, p-fluorophenol, p-chlorophenol, o-chlorophenol, and purple olophenol; Tetrahydrofuran, dioxane, cyclopentyl monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate, diethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate, and acetic acid-3-methoxy Ethers such as butyl; cyclohexanone, methyl isobutyl ketone, Ketones such as ruethylketone and diisobutylketone; N, N-dimethylformamide, N, N-dimethylacetamide, N, N-diethylformamide, 2-pyrrolidone, N-methyl-2-pyrrolidone, 1,3-dimethyl-2 Nitrogen-containing polar organic solvents such as imidazolidinone, N, N, N, N-tetramethylurea, N-methyl-ε-caprolactam, and hexamethylphosphoric triamide; ethyl acetate, methyl acetate, acetic acid-n-propyl , Isopropyl acetate, n-butyl acetate, n-pentyl acetate, methyl lactate, ethyl lactate, lactate-n-butyl, γ-butyrolactone, γ-valerolactone, and the like; dimethyl sulfoxide. These may be used alone or in combination of two or more.
Among these, from the viewpoint of further improving the thermoelectric conversion characteristics of the thermoelectric conversion element while efficiently removing excess insulating polymer material and / or conductive material from the pre-treatment film, N-methyl-2 -Pyrrolidone and methanol are preferable, and N-methyl-2-pyrrolidone is more preferable.

[Processing conditions]
Here, in the method for manufacturing a thermoelectric conversion element film of the present invention, the density of the pretreatment film _{D B (g / cm 3)} , the density of the thermoelectric conversion element film was D _{A (g} / cm ³⁾ In this case, as described above, D _A / D _B needs to be more than 0.5 and less than 0.9. D _A / D _B is preferably more than 0.7, more preferably more than 0.8, still more preferably more than 0.81, and preferably less than 0.86. More preferably, it is less than 0.85. When D _A / D _B is 0.5 or less, use as a self-supporting film becomes difficult, and when it is 0.9 or more, the effect of improving the thermoelectric conversion characteristics of the thermoelectric conversion element cannot be sufficiently obtained.
Here, the density _{D B} of pretreatment film is not particularly limited, preferably 1.1 g / cm ³ or more, more preferably 1.2 g / cm ³ or higher, preferably 1.6 g / cm ³ or less, More preferably, it is 1.5 g / cm ³ or less. The density D _A of the thermoelectric conversion element film is not particularly limited, but is preferably 0.9 g / cm ³ or more, more preferably 1.0 g / cm ³ or more, preferably 1.4 g / cm ³ or less. More preferably, it is 1.3 g / cm ³ or less.
The density D _{B of the} pre-treatment film and the density D _A of the thermoelectric conversion element film are calculated using the Archimedes method (a method of calculating the density by measuring the thickness and weight of a film cut into a certain size). can do.

Moreover, the method of making the process liquid mentioned above contact with the film before a process is not specifically limited, For example, the application | coating to the film before a process liquid, the immersion to the process liquid of a film before a process, etc. are mentioned. Among these, from the viewpoint of obtaining a film for thermoelectric conversion elements having a uniform density, it is preferable to immerse the pre-treatment film in the treatment liquid. The conditions for the immersion are not particularly limited as long as D _A / D _B is within a predetermined range. For example, the immersion liquid temperature is 25 ° C. or more and 150 ° C. or less, and the immersion time is 5 minutes or more and 12 hours or less. If too much heat is applied to the film, material modification, deterioration, reaction, and the like may occur.

(Thermoelectric conversion element film)
Since the film for thermoelectric conversion elements produced by the method for producing a film for thermoelectric conversion elements of the present invention has undergone the treatment liquid contact step described above, the excess insulating polymer material and / or conductive material is removed and the thermoelectric conversion film is removed. The conversion element can exhibit sufficiently excellent thermoelectric conversion characteristics. Moreover, since the excessive elution to the process liquid of the insulating polymer material which is a matrix resin is especially suppressed, the said film for thermoelectric conversion elements can be favorably used as a self-supporting film.

(Thermoelectric conversion element)
And the film for thermoelectric conversion elements manufactured by the manufacturing method of the film for thermoelectric conversion elements of this invention can be used for the thermoelectric conversion material layer of a thermoelectric conversion element. The structure of the thermoelectric conversion element is not particularly limited, and a known one can be adopted. A thermoelectric conversion element can be produced, for example, by attaching two electrodes to a thermoelectric conversion material layer on a substrate. An electrode is not specifically limited, For example, what is described in Unexamined-Japanese-Patent No. 2014-199837 can be used. Moreover, the positional relationship between the thermoelectric conversion material layer and the two electrodes is not particularly limited. For example, electrodes may be disposed on both ends of the thermoelectric conversion material layer, or the thermoelectric conversion material layer may be sandwiched between two electrodes.

  And such a thermoelectric conversion element can be used for a thermoelectric conversion module provided with a some thermoelectric conversion element. Examples of the thermoelectric conversion module include a thermoelectric conversion module in which a plurality of thermoelectric conversion elements are combined in a plate shape or a cylindrical shape. Such a thermoelectric conversion module includes a thermoelectric conversion element provided with the thermoelectric conversion element film produced by the method for producing a thermoelectric conversion element film of the present invention as a thermoelectric conversion material layer, so that highly efficient power generation is possible. It is.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited to these Examples. The following methods were used for evaluation and measurement.

<Power factor (PF)>
Seebeck of a film for thermoelectric conversion elements when a temperature difference of about 1 to 5 ° C. is applied in a vacuum at a temperature of 50 to 110 ° C. using a thermoelectric property evaluation apparatus (ZEM-3, manufactured by Advance Riko Co., Ltd.). The coefficient S (μV · K ⁻¹ ) and the conductivity σ (S · cm ⁻¹ ) were measured. The power factor (μW · m ⁻¹ · K ⁻² ) was calculated using the following formula.
PF = S ² × σ / 10000
The power factor is an index indicating the power generation per temperature change, and the larger the power factor, the better the thermoelectric conversion characteristics.

(Example 1)
<Preparation of carbon nanotube>
CNT (including SGCNT and single-walled CNT. Average diameter: 4.5 nm, BET specific surface area: 1020 m ² / g) was prepared by the super-growth method in accordance with the description in International Publication No. 2006/011655.
<Preparation of salt of poly (nickel 1,1,2,2-ethenetetrathiolate) (solubilized PETT)>
1,3,4,6-tetrathiapentalene-2,5-dione (TPD, manufactured by Tokyo Chemical Industry Co., Ltd.) 1 g, sodium methoxide (Wako Pure Chemical Industries, Ltd.) 1.2 g, and dodecyltrimethylammonium bromide (DTAB, 6.8 g of reagent (manufactured by Wako Pure Chemical Industries, Ltd.) was dissolved in 200 mL of methanol. The resulting solution was heated to reflux for 12 hours. Next, 0.63 g of nickel chloride (II) anhydrous (manufactured by Wako Pure Chemical Industries, Ltd.) was added to the solution. After the addition of anhydrous nickel (II) chloride, the solution was further heated to reflux for 12 hours. After refluxing for 12 hours, the solution was allowed to stand at room temperature for 12 hours to form a precipitate. The resulting black precipitate was collected by suction filtration. The collected precipitate was washed with 2 L of methanol, 2 L of water, and 50 mL of diethyl ether in this order, and then dried to obtain solubilized PETT. When the elemental composition of the obtained solubilized PETT was analyzed, the elemental composition was as follows: Ni: 15.28 mass%, Na: 0.48 mass%, S: 38.56 mass%, C: 30.76 mass%. , N: 1.49% by mass, H: 4.38% by mass. From this result, it can be seen that the solubilized PETT obtained contains sodium ions derived from sodium methoxide and dodecyltrimethylammonium ions derived from DTAB. That is, it can be seen that the obtained solubilized PETT is a mixture of sodium salt and dodecyltrimethylammonium salt.
<Preparation of film composition before treatment>
100 parts by mass of the above-mentioned carbon nanotubes, 267 parts by mass of a polyimide resin (TS-8, S1 manufactured by Solpy Co., Ltd.) as an insulating polymer material, and 300 parts by mass of the above-described solubilized PETT as an electrically conductive material -2-Pyrrolidone (NMP) was introduced into the screw tube (at this time, the solid content was 15% by mass), dispersed for 10 minutes with an ultrasonic bath, and for 10 minutes with an ultrasonic homogenizer. A composition was obtained. Solubilized PETT has a nanoparticle structure and was incorporated into the surface of SGCNT to be composited. In addition, when the particle diameter of the solubilized PETT in the composition was confirmed with a transmission electron microscope, it was 38 ± 12 nm.
<Manufacture of untreated film>
After applying the obtained composition for pre-treatment film on a quartz substrate, the substrate was heated at 60 ° C. for 10 hours to dry the composition for pre-treatment film, and the pre-treatment film (thickness: 7 μm) )
<Processing liquid contact process>
The obtained pre-treatment film was immersed in methanol (25 ° C.) as a treatment liquid for 2 hours. Thereafter, the film was pulled up from methanol and dried on a hot plate at 100 ° C. to obtain a film for a thermoelectric conversion element. Table 1 shows the density (D _B , D _A ) and ratio (D _A / D _B ) of the film before and after the treatment liquid contact process, and the power factor (PF) before and after the treatment liquid contact process. Moreover, it confirmed that the obtained film for thermoelectric conversion elements had sufficient intensity | strength, and can be used as a self-supporting film | membrane.

(Example 2)
For a thermoelectric conversion element, as in Example 1, except that NMP was used as the treatment liquid and a dryer (drying temperature: 150 ° C., drying time: 12 hours) was used instead of the hot plate for drying after immersion. A film was obtained. Table 1 shows the density (D _B , D _A ) and ratio (D _A / D _B ) of the film before and after the treatment liquid contact process, and the power factor (PF) before and after the treatment liquid contact process. Moreover, it confirmed that the obtained film for thermoelectric conversion elements had sufficient intensity | strength, and can be used as a self-supporting film | membrane.

From Table 1, in Examples 1-2, the power factor (PF) of the film for thermoelectric conversion elements is greatly improved by making it contact with a process liquid, ie, the said film for thermoelectric conversion elements is used as a thermoelectric conversion material layer. It turns out that the thermoelectric conversion characteristic sufficiently excellent in the thermoelectric conversion element can be exhibited by using.
In the conventional manufacturing method, it may be difficult to achieve both low density of the thermoelectric conversion element film and excellent self-supporting property, but according to the manufacturing method of the present invention in which the treatment liquid contact step is performed under predetermined conditions. Such a film for a thermoelectric conversion element can be produced efficiently.

  According to the method for producing a film for a thermoelectric conversion element of the present invention, it is possible to provide a film for a thermoelectric conversion element that can ensure film self-sustainability and can exhibit sufficiently excellent thermoelectric conversion characteristics.

Claims (5)

Forming a pre-treatment film using a pre-treatment film composition comprising a carbon nanotube, an insulating polymer material, and a conductive material;
A step of bringing the pre-treatment film into contact with a treatment liquid to obtain a thermoelectric conversion element film,
When the density of the pre-treatment film is D _B (g / cm ³ ) and the density of the thermoelectric conversion element film is D _A (g / cm ³ ), the value of D _A / D _B exceeds 0.5. The manufacturing method of the film for thermoelectric conversion elements which is less than 0.9.   The method for producing a film for a thermoelectric conversion element according to claim 1, wherein the conductive material contains a salt of poly (M 1,1,2,2-ethenetetrathiolate) [wherein M represents a metal].   The manufacturing method of the film for thermoelectric conversion elements of Claim 1 or 2 with which the said insulating polymer material contains a polyimide resin. The manufacturing method of the film for thermoelectric conversion elements in any one of Claims 1-3 whose specific surface area of the said carbon nanotube is 600 m < ² > / g or more.   The manufacturing method of the film for thermoelectric conversion elements in any one of Claims 1-4 in which the said process liquid contains N-methyl-2- pyrrolidone.