JP2016006849A - Thermoelectric conversion material, manufacturing method for the same and thermoelectric conversion module having the same, and use applications of the material, method, and module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermoelectric conversion material that is light, is flexible, and prevents its thermoelectric performance from deteriorating.SOLUTION: A thermoelectric conversion material having a core/sheath structure composed of a sheath part and a core part, the core part including at least one thermoelectric nanostructure. Spinning of the sheath part and the core part is performed while forming the sheath part and the core part by performing the spinning while injecting a polymer solution for forming the sheath part and a polymer solution for forming the core part into an electrospinning apparatus having a double nozzle, where the solutions are individually prepared.

Description

  The present invention relates to a thermoelectric conversion material, a production method thereof, a thermoelectric conversion module having the thermoelectric conversion material, and uses thereof.

  The thermoelectric conversion module is a solid element that can directly convert heat and electricity. An assembly in which a plurality of thermoelectric conversion materials are cut into a certain size or the like is used as a thermoelectric conversion module. The thermoelectric conversion module is generally composed of a p-type thermoelectric conversion material, an n-type thermoelectric conversion material, an electrode, and a load resistance. The thermoelectric conversion element has a very simple structure in which the materials are electrically connected in series, and has no moving parts, and thus has a feature that it can be designed compactly. Thermoelectric conversion modules are actually applied to precision temperature control of laser diodes and electronic heating / cooling chambers, etc., as well as distributed power generation technology (energy harvesting) using unused waste heat, and emergency power supplies in the event of a disaster Application as such is also expected.

  In recent years, lightweight and flexible thermoelectric conversion materials have been demanded in order to improve the degree of freedom in shape design of thermoelectric conversion modules, or to apply to next-generation thermoelectric conversion modules that are small and highly densified (non- Patent Document 1).

Further, for example, non-oxide materials such as telluride-based thermoelectric materials represented by bismuth telluride (Bi ₂ Te ₃ ) -based compounds are used as thermoelectric conversion materials having high thermoelectric power. However, some of these non-oxide materials easily react with oxygen to form oxides, resulting in a significant decrease in performance. Also, water vapor can cause deterioration of the thermoelectric conversion material. In order to deal with such problems, it has been necessary to apply advanced sealing techniques in the manufacturing process.

  Thus, the thermoelectric conversion material still had a point to be improved in terms of durability.

  Furthermore, it is also a problem that the thermoelectric conversion material is cracked by a physical stimulus such as bending.

Mikio Oyano, “Development of flexible thermoelectric module using inkjet”, [online], upbringing research: JST Innovation Plaza Ishikawa, FY 2008 project, [Search April 9, 2014], Internet <URL: http: //www.jst.go.jp/chiiki/ikusei/seika/h23/h23_ishikawa01.pdf>

  It is an object of the present invention to provide a thermoelectric conversion material that is lightweight and flexible and that is less susceptible to deterioration in thermoelectric performance.

  The present inventor has conducted extensive studies to solve the above-described problems, and is a thermoelectric conversion material having a core-sheath structure, which includes a nanostructure (thermoelectric nanostructure) having a thermoelectric conversion action in the core portion. It has been found that the material is not only lightweight and flexible, but also can protect the thermoelectric nanostructure from external factors that lead to deterioration due to the action of the sheath, and can solve the above problems.

The present invention has been completed by further various studies based on these new findings, and is as follows.
Item 1
(A) a core part; and (B) a thermoelectric conversion material having a core-sheath structure comprising a sheath part,
A thermoelectric conversion material in which the core (A) contains at least one kind of thermoelectric nanostructure.
Item 2
Item 2. The thermoelectric conversion material according to Item 1, wherein the sheath (B) contains at least one water-resistant polymer.
Item 3
Item 3. The thermoelectric conversion material according to Item 1 or 2, wherein the core (A) contains at least one gas barrier polymer that supports the thermoelectric nanostructure.
Item 4
Item 4. The thermoelectric conversion material according to any one of Items 1 to 3, wherein a major axis of the thermoelectric nanostructure is 1 to 100 nm.
Item 5
Item 5. The thermoelectric conversion material according to any one of Items 1 to 4, wherein at least one of the thermoelectric nanostructures contains a metal or an intermetallic compound.
Item 6
At least one of the thermoelectric nanostructures is selected from the group consisting of bismuth (Bi), selenium (Se), tellurium (Te), lead (Pb), antimony (Sb), germanium (Ge), and silicon (Si). Item 6. The thermoelectric conversion material according to any one of Items 1 to 5, which contains an intermetallic compound containing at least one kind.
Item 7
Item 7. The thermoelectric conversion material according to any one of Items 1 to 6, wherein at least one of the water-resistant polymers is polystyrene, polyacrylonitrile, polycarbonate, polyvinylidene fluoride, or cycloolefin.
Item 8
Item 8. The thermoelectric conversion material according to any one of Items 1 to 7, wherein at least one of the gas barrier polymers is a synthetic resin or a polysaccharide.
Item 9
Item 9. The thermoelectric conversion material according to Item 8, wherein the synthetic resin is polyvinyl alcohol, polyvinyl butyral, ethylene-vinyl alcohol copolymer, polyacrylonitrile, or polyvinylidene chloride.
Item 10
Item 10. The thermoelectric conversion material according to any one of Items 1 to 9, wherein the diameter is 3 nm to 5 μm.
Item 11
Item 11. The thermoelectric conversion material according to any one of Items 1 to 10, which can be obtained by a method of forming the core-sheath structure using an electrospinning method.
Item 12
The method for producing the thermoelectric conversion material according to any one of Items 1 to 10,
A method comprising a step of forming the core-sheath structure using an electrospinning method.
Item 13
The core (A) contains at least one thermoelectric nanostructure containing a non-oxide material and at least one polymer supporting the thermoelectric nanostructure, and the core ( The electrospinning solution for obtaining A) contains at least one reducing agent,
Item 13. The method according to Item 12.
Item 14
The electrospinning solution is at least one reducing agent selected from the group consisting of hydrazine, hydrazine monohydrate, phenylhydrazine, ethylene glycol, formaldehyde, sodium borohydride, ascorbic acid and 3-amino-1-propanol. Item 14. The method according to Item 13, which comprises
Item 15
Item 15. A thermoelectric conversion material obtainable by the method of Item 13 or 14.
Item 15
The thermoelectric conversion module containing the thermoelectric conversion material as described in any one of claim | item 1 -11 and 15.

  According to the present invention, it is possible to provide a thermoelectric conversion material that is lightweight and flexible and that is less susceptible to deterioration in thermoelectric performance. More specifically, since it is flexible, it is possible to provide a thermoelectric conversion material that is less susceptible to cracking due to physical stimulation such as bending, and that is less susceptible to degradation due to oxygen, water vapor, and other external stimuli.

It is a schematic diagram of the electrospinning apparatus used by this invention. The arrow indicates the syringe pump. It is a schematic diagram of the manufacturing method of the thermoelectric conversion material of this invention. It is a schematic diagram of the thermoelectric conversion module of this invention. It is a schematic diagram of the thermoelectric conversion module of this invention.

1. Thermoelectric conversion material The thermoelectric conversion material of the present invention comprises:
(A) a core part; and (B) a thermoelectric conversion material having a core-sheath structure comprising a sheath part,
The said core part (A) is a thermoelectric conversion material containing the nanostructure (thermoelectric nanostructure) which has at least 1 type of thermoelectric conversion effect | action.

  Since the thermoelectric conversion material of the present invention has the core-sheath structure, the thermoelectric nanostructure contained in the core part (A) is protected by the sheath part (B), so that the thermoelectric performance is hardly deteriorated. .

  In addition, the thermoelectric conversion material of the present invention is in the form of a very fine wire (nanowire) having such a core-sheath structure, and therefore has excellent characteristics of being lightweight and flexible.

  The thermoelectric conversion material of the present invention is not particularly limited, but the diameter may be 3 nm to 5 μm. In this case, the thermoelectric conversion material of the present invention is particularly preferable because it is lightweight and flexible. The diameter of the thermoelectric conversion material of the present invention is preferably 100 nm to 3 μm, and more preferably 500 nm to 3 μm.

1.1 Core (A)
The core (A) contains at least one kind of thermoelectric nanostructure.

  The size of the thermoelectric nanostructure is not particularly limited, but the major axis is usually 1 to 100 nm.

  The thermoelectric nanostructure is not particularly limited, and can be appropriately selected from a wide variety of thermoelectric materials.

  One type of thermoelectric nanostructure may be used, or two or more types may be used in appropriate combination.

  At least one of the thermoelectric nanostructures may contain a metal or an intermetallic compound. In this case, the thermoelectric nanostructure may be a metal or an intermetallic compound itself.

  At least one of the thermoelectric nanostructures is selected from the group consisting of bismuth (Bi), selenium (Se), tellurium (Te), lead (Pb), antimony (Sb), germanium (Ge), and silicon (Si). It may contain an intermetallic compound containing at least one kind.

Examples of the intermetallic compound is not particularly _{limited, Bi 2 Se 3, Bi 2} Te 3, Bi 2 Se x Te 3-x, Bi 2 Sb x Te 3-x, PbSe, PbTe, PbSe x Te 1- _x, Si, SiGe and the like.

  The core (A) may contain at least one gas barrier polymer that supports the thermoelectric nanostructure. In this case, it is preferable because the thermoelectric nanostructure can be prevented from deterioration due to oxidation or the like by the action of the gas barrier polymer.

  The gas barrier polymer is not particularly limited, and can be selected from a wide range of materials that can be used as the gas barrier polymer.

  One kind of gas barrier polymer may be used, or two or more kinds may be used in appropriate combination.

  At least one of the gas barrier polymers may be a synthetic resin or a polysaccharide.

In the above, the synthetic resin is not particularly limited, but the oxygen permeability coefficient is preferably 10 ⁻¹⁴ [cm ³ (STP) cm / (cm ² · s · Pa)] or less, more preferably 10 ⁻¹⁵ [cm ³ ( STP) cm / (cm ² · s · Pa)] or less, more preferably 10 ⁻¹⁶ [cm ³ (STP) cm / (cm ² · s · Pa)] or less synthetic resin.

  In the present invention, the oxygen transmission coefficient is measured by the differential pressure method as follows.

  The test film to be measured is dried in a desiccator for 48 hours or more at the same temperature as the test temperature.

The dried film is set in a permeation cell that is permeable to gas and fixed so that there is no air leakage. The low-pressure side and the high-pressure side are exhausted in this order, and the permeation cell is kept in a vacuum. Oxygen is injected up to about 1 atm on the high pressure side, and the pressure (P _u ) on the high pressure side at this time is recorded. Thereafter, it is confirmed that the gas permeates through the test film and the pressure on the low pressure side increases. A transmission curve is drawn and the measurement is continued until this curve becomes a straight line, that is, until the transmission reaches a steady state. The slope (d _p / d _t ) of the straight line portion of the permeation curve is obtained, and the gas permeability is obtained from the following equation.
Formula: GTR = V _c / (R × T × P _u × A) × d _p / d _t

Here, GTR is the gas permeability (mol / m ² · Pa), V _c is the low pressure side volume (L), T is the test temperature, _Pu is the pressure difference of the supplied gas (Pa), and A is the permeation area (m ² ), d _p / d _t is the pressure change (Pa) on the low pressure side in unit time (s), and R is the gas constant of 8.31 × 10 ³ (L · Pa / K · mol).

The gas permeability coefficient (P) is calculated by the following equation.
Formula: P = GTR × d

Here, P is a gas permeability coefficient (mol · m / m ² · Pa), and d is a thickness (m) of the test film.

  The synthetic resin that is a gas barrier polymer is not particularly limited, and examples thereof include polyvinyl alcohol, polyvinyl butyral, ethylene-vinyl alcohol copolymer, polyacrylonitrile, and polyvinylidene chloride.

  When the core (A) contains a gas barrier polymer, the ratio is not particularly limited, but the ratio of the thermoelectric nanostructure to the gas barrier polymer is 5:95 to 50:50 (weight ratio), preferably It can be appropriately set within the range of 10:90 to 50:50 (weight ratio), more preferably 30:70 to 50:50 (weight ratio).

  The core (A) may further contain other components. Examples of other components include, but are not limited to, for example, carbon-based fillers for improving conductivity such as nanocarbon, amorphous carbon, carbon nanotubes, and graphene, and antioxidants such as L-ascorbic acid and sodium sulfite. Can be mentioned.

  Although the diameter of a core part (A) is not specifically limited, Usually, they are 3 nm-500 nm.

  The cross-sectional shape of the core (A) is not particularly limited, but is usually a circle or an ellipse.

1.2 Sheath (B)
A sheath part (B) has an effect | action which protects a core part (A), and as long as it is not limited in particular.

  Although a sheath part (B) can be suitably set according to the objective, it can contain a water-resistant polymer, for example. Thereby, a core part (A) can be mainly protected from a water | moisture content.

  The water resistant polymer is not particularly limited and can be appropriately selected from those usable as the water resistant polymer.

  One type of water-resistant polymer may be used, or two or more types may be used in appropriate combination.

  The water-resistant polymer is not particularly limited, but those having a water absorption rate of 0.1 (wt%, 24 hours) or less are preferable.

  In the present invention, the water absorption rate (% by weight, 24 hours) is measured as follows.

  The water absorption is measured based on JIS K7209 (plastic water absorption and boiling water absorption test method). Specifically, it is as follows.

  A test piece having a square of 50 ± 1 mm per side and a thickness of 3 ± 0.2 mm is used. Conditioning of the test piece is dried for 24 ± 1 hours in a constant temperature bath maintained at 50 ± 2 ° C. and allowed to cool in a desiccator.

It weighed mass of conditioned specimens to 0.1 mg, which is referred to as _{M 1.} Place the specimen in a container in water maintained at 23 ± 2 ° C. After 24 ± 1 hour, taken out a test piece from the water, weighed again to 0.1 mg, which is referred to as _{M 2.}

The amount of immersion liquid (water or boiling water) to be used is 8 mL or more per 1 cm ^{2 of} the test piece in order to avoid the influence of the change of the immersion liquid due to the extract from the test piece during the test.

The water absorption is obtained from the following formula from M ₁ and M ₂ obtained by the measurement.
Formula: (M ₂ −M ₁ ) / M ₁ × 100 (%)

  At least one of the water-resistant polymers may be polystyrene, polyacrylonitrile, polyvinylidene fluoride, or cycloolefin.

  The ratio of the component of the sheath (B) to the component of the core (A) is not particularly limited, but is 10:90 to 80:20 (weight ratio), preferably 10:90 to 70:30 (weight ratio). More preferably, it can be appropriately set within the range of 10:90 to 50:50. If the ratio of the component of the sheath (B) to the component of the core (A) is equal to or higher than the lower limit of the numerical range, water resistance is more easily secured, and it is sufficient if the ratio is equal to or lower than the upper limit of the numerical range. Thermoelectric performance is easily obtained.

  The sheath (B) may further contain other components. Examples of other components include, but are not limited to, carbon-based fillers for ensuring conductivity such as nanocarbon, carbon nanotubes, and graphene, and inorganic materials that improve heat resistance and mechanical properties such as silica and alumina. A filler etc. can be mentioned.

2. Production Method of Thermoelectric Conversion Material The thermoelectric conversion material of the present invention is not particularly limited, but can be produced by a method including a step of forming the core-sheath structure using an electrospinning method (electrospinning method), for example. .

  The electrospinning method is a method of forming nano-sized fibers by supplying a solution for electrospinning containing a polymer material in an atmosphere in which an electric field is formed. Two types of methods, the nozzle method, are generally known. The needle nozzle method is known as a method of discharging an electrospinning solution sealed in a syringe into an atmosphere in which an electric field is formed from the tip of a metal needle nozzle. As the non-nozzle type electrospinning method (electrospinning method), a drum-type electrospinning method and an electrobubble spinning method are mainly known. Among them, the drum-type electrospinning method is known as a method for performing electrospinning by partially immersing a rotating drum-type electrode in an electrospinning solution (for example, Nanospider manufactured by El Marco Co., Ltd .: Special Table) In addition, the electrobubble spinning method is known as a method for performing electrospinning by applying a high voltage to bubbles continuously generated in a solution for electrospinning (for example, Hirose Paper Co., Ltd.). Company electrospinning method: see Japanese Patent Application Laid-Open No. 2008-025057).

  As described above, since various electrospinning methods are conventionally known, these methods can be used as they are or after being appropriately modified as necessary in producing the thermoelectric conversion material of the present invention.

  Specifically, it can be spun while forming the core and sheath by electrospinning. This can be easily done, for example, by using an electrospinning apparatus comprising a double nozzle (FIG. 1) having a core layer and a sheath layer. Specifically, by separately preparing a polymer solution for forming the core part and a polymer solution for forming the sheath part, these are injected into an electrospinning apparatus equipped with a double nozzle and spun. In addition, spinning can be performed while forming the core and the sheath (FIG. 2).

  Alternatively, only the core portion can be spun by electrospinning, and the sheath portion can be formed around the core portion by another method. The other method for forming the sheath portion around the core portion is not particularly limited, and examples thereof include a method of immersing the core portion in a solution containing a water-resistant polymer.

  Moreover, if necessary, the thermoelectric nanostructure can be protected from oxidative degradation by using an electrospinning solution for forming the core part containing at least one reducing agent.

  The reducing agent is not particularly limited.

  A reducing solvent can also be used as the reducing agent. As the reducing solvent, a solvent capable of dissolving or dispersing the thermoelectric nanostructure and the polymer supporting the thermoelectric nanostructure can be appropriately selected from the solvents exhibiting the reducing ability.

  Although it does not specifically limit as a reducing agent, For example, hydrazine, hydrazine monohydrate, phenylhydrazine, ethylene glycol, formaldehyde, sodium borohydride, ascorbic acid, 3-amino-1-propanol, etc. can be used.

  The concentration of the reducing agent in the total solvent of the electrospinning solution for obtaining the core (A) is not particularly limited, but is usually 5 to 80% by weight, preferably 20 to 80% by weight, and more. Preferably it is 30 to 80% by weight.

  The ratio of the thermoelectric nanostructure to the gas barrier polymer in the electrospinning solution for obtaining the core (A) is not particularly limited, but is usually 10:90 to 70:30 (weight ratio), preferably Is 20: 80-60: 40 (weight ratio), more preferably 30: 50-50: 50 (weight ratio).

  Since the thermoelectric conversion material of the present invention is obtained by the production method using the above-described reducing agent, the oxidation of the thermoelectric conversion material in the core (A) is suppressed.

  Although not particularly limited, when obtained by the above-described production method using a reducing agent, in some embodiments, the reducing solvent used during electrospinning remains in the core (A). At this time, due to the action of the reducing solvent, the thermoelectric conversion material is hardly oxidized in the core (A) even after molding.

  In addition, a non-woven fabric film having no orientation can be formed by electrospinning, and a highly oriented film can be formed by using an accumulating apparatus that rotates at high speed.

  A non-oriented non-woven fabric film is less likely to have anisotropy in conductivity, but a film having an orientation property can have anisotropy in conductivity.

  The orientation strength can be adjusted by the rotational speed of the rotating stacking device.

3. Thermoelectric Conversion Module The thermoelectric conversion module of the present invention includes the thermoelectric conversion material.

  Although not particularly limited, usually, the thermoelectric conversion module of the present invention is an aggregate in which a plurality of the thermoelectric conversion materials are cut into a certain size.

  An example of a conceptual diagram of the thermoelectric conversion module is shown in FIG. The thermoelectric conversion module is generally configured by electrically connecting a p-type thermoelectric material and an n-type thermoelectric material in series via electrodes.

  As shown in FIG. 3, the thermoelectric conversion module of the present invention may be provided with an electrical insulating material such as an insulating heat dissipation material on the upper and lower surfaces as needed. The insulating heat dissipating material can be appropriately selected depending on the application. For example, a film or rubber containing alumina can be used. If flexibility is not required, ceramic or the like may be used as the insulating heat dissipation material.

  The thermoelectric conversion module of the present invention can be produced according to a conventionally known method.

  Although not particularly limited, as shown in FIG. 4, two kinds of non-woven fabrics having high orientation having a p-type thermoelectric conversion material and an n-type thermoelectric conversion material at the core are prepared (see FIG. 4). A) Each non-woven fabric is cut into strips so that the direction along the fiber orientation direction is the long side (B in FIG. 4), and the p-type thermoelectric conversion material and the n-type thermoelectric conversion material are in contact with each other. By laminating various types of cut nonwoven fabrics (C in FIG. 4), the short sides where the p-type thermoelectric conversion material and the n-type thermoelectric conversion material are in contact with the die are connected by electrodes (E in FIG. 4). ), It becomes easy to ensure conductivity.

  The thermoelectric conversion module of the present invention is roughly classified into a thermoelectric cooling module (Peltier module) and a thermoelectric power generation module depending on applications.

  The thermoelectric cooling module of the present invention is not particularly limited, but can be used for incorporation into optical communication equipment, cold storage, constant temperature water circulation devices and other equipment and devices for the purpose of cooling various parts and controlling temperature. Further, the thermoelectric cooling module can be used for so-called thermoelectric power generation, in which electricity is generated using heat by utilizing this reverse action in addition to the above-described various uses for controlling (cooling) temperature by electricity.

  The thermoelectric power generation module of the present invention is not particularly limited, but includes various power sources such as artificial satellites, power supplies for desert wireless relay stations and other local areas, independent power supplies such as sensors and wearable devices, or emergency power supplies in the event of a disaster. Can be used for special purposes.

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

I. Example 1
1. Synthesis of thermoelectric nanostructures Thermoelectric nanostructures were synthesized by methods known in the art (for example, X. B. Zuao, et al., “Hydrogenetic synthesis and microstructural of nanostructured pour. A, 80, pp. 1567-1571).

2. Preparation of core (A) polymer solution 17.5 parts by weight of polyvinyl alcohol (SELVOL 205: manufactured by Sekisui Chemical Co., Ltd.), which is a gas barrier polymer, was dissolved in 82.5 parts by weight of distilled water to obtain a uniform solution. The thermoelectric nanostructure was added to the polymer solution so that the ratio of the thermoelectric nanostructure to the gas barrier polymer was 50:50 (weight ratio) and dispersed uniformly to obtain a solution. This solution was designated as “core (A) polymer solution”.

3. Preparation of sheath (B) polymer solution 10 parts by weight of polyacrylonitrile (Mw: 150,000: made by Aldrich) which is a water-resistant polymer is dissolved in 90 parts by weight of N, N-dimethylformamide to obtain a uniform solution. It was. This solution was designated as “sheath (B) polymer solution”.

4). The electrospun core (A) polymer solution was filled into the core layer of a double nozzle (manufactured by Imoto Seisakusho), and the sheath (B) polymer solution was filled into the sheath layer (FIG. 1). The flow rate of the syringe pump that sends the core part (A) polymer solution is set to 0.2 mL / h, and the flow rate of the syringe pump that sends the sheath part (B) polymer solution is set to 0.6 mL / h. A core-sheath thermoelectric conversion material was obtained by a spinning method (FIG. 2). The outer diameter of the core layer of the double nozzle was 0.26 mm, the outer diameter of the sheath layer was 0.92 mm, the applied voltage was 20 kV, and the distance from the double nozzle to the collector was 10 cm. The collector was used as a cathode during spinning. The obtained core-sheath structure thermoelectric conversion material had an average diameter of 0.5 μm.

II. Example 2
A nanofiber sheet was obtained by the electrospinning method in the same manner as in Example 1 using only the core (A) polymer solution. The obtained nanofibers comprising the core polymer (A) had an average diameter of 0.1 μm. The obtained nanofiber sheet was immersed in the sheath part (B) polymer solution, pulled from the solution and dried to obtain a core-sheath structure thermoelectric conversion material. The obtained core-sheath structure thermoelectric conversion material had an average diameter of 0.5 μm.

III. Example 3
The core was prepared in the same manner as in Example 1 except that 30 parts by weight of butyral (BL-1: manufactured by Sekisui Chemical Co., Ltd.) was dissolved in 70 parts by weight of N, N-dimethylformamide to form a core (A) polymer solution. A sheath-structured thermoelectric conversion material was obtained.

IV. Example 4
Example 1 except that 14 parts by weight of an ethylene-vinyl alcohol copolymer (manufactured by Kuraray Co., Ltd .: “EVAL-G”) was dissolved in 86 parts by weight of dimethyl sulfoxide to form a core (A) polymer solution. A core-sheath thermoelectric conversion material was obtained in the same manner.

V. Example 5
A sheath (B) polymer solution was prepared by dissolving 20 parts by weight of polystyrene (DIC Corporation: “Lurex A-14”), which is a water-resistant polymer, with 80 parts by weight of N, N-dimethylformamide. Except for the points, a core-sheath thermoelectric conversion material was obtained in the same manner as in Example 1.

VI. Example 6
Example except that 25 parts by weight of polyvinylidene fluoride (Aldrich: molecular weight 180,000) which is a water-resistant polymer was dissolved in 75 parts by weight of N, N-dimethylacetamide as a sheath (B) polymer solution 1 to obtain a core-sheath thermoelectric conversion material.

VII. Example 7
1. Synthesis of thermoelectric nanostructures Thermoelectric nanostructures were synthesized in the same manner as in Example 1.

2. Preparation of core (A) polymer solution 15 parts by weight of polyvinyl alcohol (SELVOL 205: Sekisui Chemical Co., Ltd.), which is a gas barrier polymer, is dissolved in 30 parts by weight of ethylene glycol and 55 parts by weight of distilled water to obtain a uniform solution. Obtained. A thermoelectric nanostructure was added to the polymer solution so that the ratio of the thermoelectric nanostructure to the gas barrier polymer was 50:50 (weight ratio) and uniformly dispersed to obtain a solution. This solution was designated as “core (A) polymer solution”.

3. Preparation of sheath (B) polymer solution 10 parts by weight of polyacrylonitrile (Aldrich: Mw 150,000 :) which is a water-resistant polymer was dissolved in 90 parts by weight of N, N-dimethylformamide to obtain a uniform solution. . This solution was designated as “sheath (B) polymer solution”.

4). The electrospun core (A) polymer solution was filled in the core layer of the double nozzle (manufactured by Imoto Seisakusho), and the sheath (B) polymer solution was filled in the sheath layer (FIG. 1). The flow rate of the syringe pump for feeding the core (A) polymer solution is set to 0.2 mL / h, and the flow rate of the syringe pump for feeding the sheath (B) polymer solution is set to 0.6 mL / h. Core-sheath nanofibers were obtained by electrospinning (FIG. 2). The outer diameter of the core layer of the double nozzle was 0.26 mm, the outer diameter of the sheath layer was 0.92 mm, the applied voltage was 20 kV, and the distance from the double nozzle to the collector was 10 cm. The collector was used as a cathode during spinning.

VIII. Example 8
A core (A) polymer solution prepared by dissolving 30 parts by weight of butyral (BL-1: manufactured by Sekisui Chemical Co., Ltd.), a gas barrier polymer, with 30 parts by weight of ethylene glycol and 40 parts by weight of N, N-dimethylformamide A core-sheath structure thermoelectric conversion material was obtained in the same manner as in Example 1 except that.

IX. Example 9
Example 1 except that 14 parts by weight of ethylene-vinyl alcohol copolymer (manufactured by Kuraray Co., Ltd .: “EVAL-G”) dissolved in 86 parts by weight of ethylene glycol was used as the core (A) polymer solution. A core-sheath thermoelectric conversion material was obtained in the same manner.

X. Example 10
A sheath (B) polymer solution is obtained by dissolving 20 parts by weight of polystyrene (made by DIC Corporation: “Lurex A-14”), which is a water-resistant polymer, with 80 parts by weight of N, N-dimethylformamide. Except for the above, a core-sheath thermoelectric conversion material was obtained in the same manner as in Example 1.

XI. Example 11
Example 1 except that 25 parts by weight of polyvinylidene fluoride which is a water-resistant polymer (manufactured by Aldrich: molecular weight 180,000) dissolved in 75 parts by weight of N, N-dimethylacetamide was used as a sheath (B) polymer solution. A core-sheath thermoelectric conversion material was obtained in the same manner as described above.

XII. Example 12
A sheath-shell thermoelectric conversion material was obtained in the same manner as in Example 1 except that the sheath (B) polymer solution contained 5 parts by weight of single-walled carbon nanotubes (manufactured by KH Chemical Co .: “KH SWCNT HP”). .

XIII. Example 13
The collector of Example 1 was used as a roll having a roll surface speed of 1000 m / min to obtain an oriented core-sheath structure thermoelectric conversion material.

DESCRIPTION OF SYMBOLS 1 Electrospinning apparatus 11 Sheath part layer 12 Core part layer 2 Thermoelectric conversion module 21 p-type thermoelectric conversion material 22 n-type thermoelectric conversion material 23 Electrode 24 Insulating heat dissipation material 25 Lead

Claims (16)

(A) a core part; and (B) a thermoelectric conversion material having a core-sheath structure comprising a sheath part,
A thermoelectric conversion material in which the core (A) contains at least one kind of thermoelectric nanostructure. The thermoelectric conversion material according to claim 1, wherein the sheath (B) contains at least one water-resistant polymer. The thermoelectric conversion material according to claim 1 or 2, wherein the core (A) contains at least one gas barrier polymer that supports the thermoelectric nanostructure. The thermoelectric conversion material according to any one of claims 1 to 3, wherein a major axis of the thermoelectric nanostructure is 1 to 100 nm. The thermoelectric conversion material according to any one of claims 1 to 4, wherein at least one of the thermoelectric nanostructures contains a metal or an intermetallic compound. At least one of the thermoelectric nanostructures is selected from the group consisting of bismuth (Bi), selenium (Se), tellurium (Te), lead (Pb), antimony (Sb), germanium (Ge), and silicon (Si). The thermoelectric conversion material as described in any one of Claims 1-5 containing the intermetallic compound containing at least 1 type. The thermoelectric conversion material according to any one of claims 1 to 6, wherein at least one of the water-resistant polymers is polystyrene, polyacrylonitrile, polycarbonate, polyvinylidene fluoride, or cycloolefin. The thermoelectric conversion material according to any one of claims 1 to 7, wherein at least one of the gas barrier polymers is a synthetic resin or a polysaccharide. The thermoelectric conversion material according to claim 8, wherein the synthetic resin is polyvinyl alcohol, polyvinyl butyral, ethylene-vinyl alcohol copolymer, polyacrylonitrile, or polyvinylidene chloride. The thermoelectric conversion material according to any one of claims 1 to 9, wherein the diameter is 3 nm to 5 µm. The thermoelectric conversion material as described in any one of Claims 1-10 which can be obtained by the method of shape | molding the said core-sheath structure using an electrospinning method. A method for producing the thermoelectric conversion material according to any one of claims 1 to 10,
A method comprising a step of forming the core-sheath structure using an electrospinning method. The core (A) contains at least one thermoelectric nanostructure containing a non-oxide material and at least one polymer supporting the thermoelectric nanostructure, and the core ( The electrospinning solution for obtaining A) contains at least one reducing agent,
The method of claim 12. The electrospinning solution is at least one reducing agent selected from the group consisting of hydrazine, hydrazine monohydrate, phenylhydrazine, ethylene glycol, formaldehyde, sodium borohydride, ascorbic acid and 3-amino-1-propanol. The method according to claim 13, comprising: The thermoelectric conversion material which can be obtained by the method of Claim 13 or 14. The thermoelectric conversion module containing the thermoelectric conversion material as described in any one of Claims 1-11 and 15.