WO2016147809A1 - Waste heat recovery sheet - Google Patents

Abstract

The present invention provides a waste heat recovery sheet which increases the degree of freedom with respect to the location where a thermoelectric conversion device can be disposed, and with which energy regeneration is possible. The waste heat recovery sheet is disposed in at least one part of a heat source and includes a substrate and a sheet-shaped thermoelectric conversion device which is disposed on the surface of the substrate and which has a thermoelectric conversion layer formed from a thermoelectric material and an electrode layer that is connected to the thermoelectric conversion layer. The waste heat recovery sheet is configured so as to satisfy the following formula with regard to: the thermal conductivity of the heat source; the thickness in the direction in which the temperature gradient of the heat source is generated; the thermal conductivity of the substrate; the thickness of the substrate; the thermal conductivity of the thermoelectric material; and the thickness of the thermoelectric conversion layer. Formula: {(thermal conductivity of the heat source) × (the thickness in the direction in which the temperature gradient of the heat source is generated)} + {(the thermal conductivity of the substrate) × (the thickness of the substrate)} > {(thermal conductivity of the thermoelectric material) × (the thickness of the thermoelectric conversion layer)}

Description

Waste heat recovery sheet

The present invention relates to an exhaust heat recovery sheet having thermoelectric conversion capability.

A thermoelectric conversion device is a device that generates a potential difference due to a temperature difference that occurs at both ends of a conductor. If thermal energy can be recovered as electrical energy from a place where a constant temperature difference occurs using a thermoelectric conversion device, it will contribute to energy saving.
Therefore, it has been studied to regenerate heat energy emitted from the heat sink as electric energy by arranging the thermoelectric conversion device on the heat sink (see Patent Document 1). In Patent Document 1, as shown in FIG. 2, bulk P-type semiconductor elements and N-type semiconductor elements are alternately arranged via electrode layers between two insulating heat transfer plates such as ceramics and connected to each other. A thermoelectric conversion device is used.
Examples of a heat source that constantly obtains a temperature difference include heat generated by daily life (referred to as exhaust heat from daily life), heat generated by operation of a factory (referred to as factory exhaust heat), and the like.

International Publication No. 2010/090350

The above-mentioned life exhaust heat and factory exhaust heat are useful as heat sources in energy regeneration using a thermoelectric conversion device. However, the temperature of daily exhaust heat and factory exhaust heat is approximately 100 ° C. or less, and the place where daily exhaust heat and factory exhaust heat can be obtained includes pipes for transferring hot water, steam, etc., and equipment that generates heat. It is the housing surface. For this reason, when installing in such a heat source, the thermoelectric conversion device is required to have high followability to the surface shape of the installation location. Furthermore, even if the temperature difference which arises in a thermoelectric conversion device is as small as 100 degrees C or less, it is calculated | required that energy conversion is possible.
Then, this invention makes it a subject to provide the exhaust heat recovery sheet | seat which raises the freedom degree of the arrangement place of a thermoelectric conversion device, and can regenerate energy.

The present invention provides the following (1) to (8).
(1) A sheet-like base material disposed on at least a part of a heat source, a thermoelectric conversion layer formed on a surface of the base material and formed from a thermoelectric material, and an electrode layer connected to the thermoelectric conversion layer A sheet-like thermoelectric conversion device having, the heat conductivity of the heat source, the thickness in the direction in which the temperature gradient of the heat source occurs, the heat conductivity of the substrate, the thickness of the substrate, the heat conductivity of the thermoelectric material, And the exhaust heat recovery sheet | seat with which the thickness of this thermoelectric conversion layer satisfy | fills a following formula.
{(Heat conductivity of heat source) × (thickness in the direction in which the temperature gradient of the heat source is generated)} + {(heat conductivity of the base material) × (thickness of the base material)}> {(thermal conductivity of thermoelectric material) ) × (thickness of the thermoelectric conversion layer)}
(2) The exhaust heat recovery sheet according to (1), wherein a current direction of a thermoelectric conversion layer constituting the thermoelectric conversion device is arranged in parallel to a plane of the base material.
(3) The exhaust heat recovery sheet according to (1), wherein a current direction of a thermoelectric conversion layer constituting the thermoelectric conversion device is arranged so as to intersect a plane of the base material.
(4) The exhaust heat recovery sheet according to any one of (1) to (3), wherein the thermoelectric material of the thermoelectric conversion device has a thermal conductivity of 30 W / m · K or less.
(5) The exhaust heat recovery sheet according to any one of (1) to (4), wherein the thermoelectric material of the thermoelectric conversion device is an n-type thermoelectric material.
(6) The exhaust heat recovery sheet according to any one of (1) to (4), wherein the thermoelectric material of the thermoelectric conversion device is a p-type thermoelectric material.
(7) The thermoelectric material of the thermoelectric conversion device is an n-type thermoelectric material and a p-type thermoelectric material, an n-type thermoelectric conversion layer made of the n-type thermoelectric material, and a p-type thermoelectric conversion layer made of the p-type thermoelectric material; The exhaust heat recovery sheet according to any one of (1) to (6), wherein the exhaust heat recovery sheets are connected by the electrode layer.
(8) The exhaust heat recovery sheet according to any one of (1) to (7), further including a power storage unit that stores electricity, wherein the electrode layer is electrically connected to the power storage unit.

According to the present invention, it is possible to provide a waste heat recovery sheet that can increase the degree of freedom of the location of the thermoelectric conversion device and can recover energy from life waste heat and factory waste heat.

It is a schematic diagram explaining the structure of 1 A of waste heat recovery sheets which concern on embodiment of this invention. It is a schematic diagram explaining the structure of the waste heat recovery sheet | seat 1B which concerns on embodiment of this invention. It is an appearance perspective view of exhaust heat recovery sheet 1C concerning an embodiment of the present invention. It is a figure for demonstrating the internal structure of the waste heat recovery sheet | seat 1C which concerns on embodiment of this invention, (a) is a perspective view which shows one pattern film 30 which comprises the waste heat recovery sheet | seat 1C, ( b) is a perspective view showing the other pattern film 40 to be opposed to each other.

Hereinafter, an outline of the exhaust heat recovery sheet according to the embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram illustrating the structure of the exhaust heat recovery sheet 1A according to the present embodiment, and FIG. 2 is a schematic diagram illustrating the structure of the exhaust heat recovery sheet 1B. 1 and 2 are plan views of the exhaust heat recovery sheet 1A and the exhaust heat recovery sheet 1B as viewed from the direction perpendicular to the main surface. The exhaust heat recovery sheet 1 can take two structures shown in FIGS. 1 and 2 according to the type of thermoelectric conversion layer described later.

[Exhaust heat recovery sheet]
The exhaust heat recovery sheet 1 </ b> A according to the embodiment of the present invention is disposed on at least a part of a heat source, and includes a sheet-like base material 10 and a sheet-like thermoelectric conversion device 20. The thermoelectric conversion device 20 includes a thermoelectric conversion layer 22 that is disposed on the surface of the substrate 10 and is formed from a thermoelectric material, and an electrode layer 23 that is connected to the thermoelectric conversion layer 22.
And the heat conductivity of the heat source, the thickness in the direction in which the temperature gradient of the heat source is generated, the heat conductivity of the substrate 10, the thickness of the substrate 10, the heat conductivity of the thermoelectric material, and the thickness of the thermoelectric conversion layer 22 are as follows: Satisfy the formula.
{(Heat conductivity of heat source) × (thickness in the direction in which the temperature gradient of the heat source is generated)} + {(heat conductivity of the base material) × (thickness of the base material)}> {(thermal conductivity of thermoelectric material) ) × (thickness of the thermoelectric conversion layer)}
In the present embodiment, the left side of the above formula {(heat conductivity of the heat source) × (thickness in the direction in which the temperature gradient of the heat source is generated)} + {(heat conductivity of the substrate) × (thickness of the substrate)} Is defined as the rated capacity of the heat source. Further, the right side {(thermal conductivity of thermoelectric material) × (thickness of the thermoelectric conversion layer)} in the above formula is defined as the rated capacity of the thermoelectric material.
In the exhaust heat recovery sheet according to this embodiment, if the rated capacity of the heat source exceeds the rated capacity of the thermoelectric material, a sufficient temperature difference can be given to the thermoelectric conversion device regardless of the type and number of layers of the thermoelectric material. Electric energy can be obtained.
In this embodiment, a thermoelectric material is a material that can convert thermal energy into electrical energy, and a semiconductor that can convert thermal energy into electrical energy is called a thermoelectric semiconductor.

<Base material>
The substrate 10 is not particularly limited as long as it does not affect the decrease in the electric conductivity of the thermoelectric material. Examples of the substrate include glass, silicon, and plastic film. Of these, a plastic film is preferable because of its excellent flexibility.
Specific examples of the plastic film include polyethylene terephthalate film, polyethylene naphthalate film, polyimide film, polyamide film, polyetherimide film, polyaramid film, polyamideimide film, polyetherketone film, polysulfone film, and polyether ether. Examples thereof include ketone films, polyphenylene sulfide films, poly (4-methylpentene-1) films, and the like. Moreover, the laminated body of these films may be sufficient.
Among these, when annealing a thin film made of a thermoelectric material, the performance of the thermoelectric material can be maintained, there is no thermal deformation, and the heat resistance and dimensional stability are high. A polyamide film, a polyetherimide film, a polyaramid film, and a polyamideimide film are preferable, and a polyimide film is particularly preferable from the viewpoint of high versatility.
The thickness of the substrate 10 is preferably 0.01 to 1000 μm, more preferably 0.01 to 100 μm, and more preferably 0.01 to 25 μm from the viewpoints of flexibility, heat resistance, and dimensional stability. When an inorganic thermoelectric material is used, the decomposition temperature of the substrate 10 is preferably 300 ° C. or higher.

<Thermoelectric conversion device>
The thermoelectric conversion device 20 is formed of a thermoelectric conversion layer 22 and an electrode layer 23. The thermoelectric conversion layer 22 is formed in a rectangular shape on the surface of the base material 10, and an electrode layer 23 is connected to one end and the other end in the longitudinal direction of the rectangle.
When the thermoelectric conversion layer 22 formed of either a p-type thermoelectric material or an n-type thermoelectric material is used as the thermoelectric material, for example, in the longitudinal direction of the adjacent thermoelectric conversion layers 22 as shown in FIG. One upper end and the other lower end are connected by an electrode layer 23.
Further, when a p-type thermoelectric material and an n-type thermoelectric material are used, as shown in FIG. 2, for example, a thermoelectric conversion layer 22a formed from a p-type thermoelectric material and a thermoelectric formed from an n-type thermoelectric material. The conversion layer 22b is connected by the electrode layer 23 so as to be connected in series.
In the thermoelectric conversion device 20 shown in FIGS. 1 and 2, the current direction of the thermoelectric conversion layer 22 is arranged in parallel to the plane of the substrate 10.
In this embodiment, the thermoelectric conversion device 20 thus formed has one end portion disposed on the high temperature side and the other end portion disposed on the low temperature side in order to be used as a power generation device. That is, when the thermoelectric conversion device 20 is disposed in the heat source, the thermoelectric conversion layer 22 (22a, 22b) is preferably disposed so that the longitudinal direction thereof is along the upright direction V where the temperature gradient occurs.
The thickness of the thermoelectric conversion device 20 according to this embodiment is preferably 0.2 to 2000 μm, more preferably 0.2 to 1000 μm, and more preferably 0.2 to 100 μm.
Although not shown in FIGS. 1 and 2, an electrode for extracting a thermoelectromotive force is connected to the electrode layer 23 of the thermoelectric conversion device 20, and the thermoelectromotive force is taken out from the thermoelectric conversion device 20. Can be stored in a power storage device or used as a power source for the device. Next, each configuration of the thermoelectric conversion device 20 will be described in detail.

(Thermoelectric conversion layer)
The thermoelectric conversion layer 22 is formed from a thermoelectric material having a Seebeck effect. The thermoelectric material that can form the thermoelectric conversion layer 22 includes the heat conductivity of the heat source, the thickness in the direction in which the temperature gradient of the heat source occurs, the heat conductivity of the substrate, the thickness of the substrate, and the heat conductivity of the thermoelectric material. The rate and the thickness of the thermoelectric conversion layer must satisfy the relationship of the following formula.
{(Heat conductivity of heat source) × (thickness in the direction in which the temperature gradient of the heat source is generated)} + {(heat conductivity of the base material) × (thickness of the base material)}> {(thermal conductivity of thermoelectric material) ) × (thickness of the thermoelectric conversion layer)}

As the thermoelectric material, either an inorganic material or an organic material can be used.
Examples of inorganic thermoelectric materials include bismuth-tellurium-based thermoelectric semiconductor materials such as p-type bismuth telluride, n-type bismuth telluride and Bi ₂ Te ₃ ; telluride-based thermoelectric semiconductor materials such as GeTe and PbTe; antimony-tellurium-based thermoelectric semiconductors Materials: zinc-antimony thermoelectric semiconductor materials such as ZnSb, Zn ₃ Sb _{2 and} Zn ₄ Sb ₃ ; silicon-germanium thermoelectric semiconductor materials such as SiGe; bismuth selenide thermoelectric semiconductor materials such as Bi ₂ Se ₃ ; β- Silicide-based thermoelectric semiconductor materials such as FeSi ₂ , CrSi ₂ , MnSi _1.73 and Mg ₂ Si; Oxide-based thermoelectric semiconductor materials such as ZnO; Heusler materials such as FeVAl, FeVAlSi and FeVTiAl; TiS ₂ and tetrahedrite Sulfide-based thermoelectric semiconductor materials can be used The
Among these, thermoelectric materials suitable for use in the present embodiment are p-type bismuth telluride, n-type bismuth telluride, Bi ₂ Te _{3 and} other bismuth-tellurium-based thermoelectric semiconductor materials.
As p-type bismuth telluride, carriers are holes and the Seebeck coefficient is a positive value, and for example, those represented by Bi _X Te ₃ Sb _2-X are preferably used. In this case, X is preferably 0 <X ≦ 0.8, and more preferably 0.4 ≦ X ≦ 0.6. It is preferable that X is greater than 0 and less than or equal to 0.8 because the Seebeck coefficient and electrical conductivity are increased, and the characteristics as a p-type thermoelectric conversion material are maintained.
As the n-type bismuth telluride, the carrier is an electron and the Seebeck coefficient is a negative value. For example, those represented by Bi ₂ Te _3-Y Se _Y are preferably used. In this case, Y is preferably 0 ≦ Y ≦ 3, and more preferably 0 ≦ Y ≦ 2.7. It is preferable that Y is 0 or more and 3 or less because the Seebeck coefficient and electrical conductivity are increased, and the characteristics as an n-type thermoelectric conversion material are maintained.
The thickness of the thermoelectric conversion layer 22 formed from an inorganic thermoelectric material is preferably 0.1 μm or more and 1000 μm or less, and more preferably 0.1 μm or more and 100 μm or less. When the thickness is less than 0.1 μm, the electric resistance is high and sufficient performance cannot be obtained. When the thickness exceeds 1000 μm, the cost for the film forming process becomes excessive, and the cost effectiveness is deteriorated.

The thermoelectric conversion layer 22 may be made of a thermoelectric semiconductor composition containing fine particles of a thermoelectric semiconductor, a heat resistant resin, and an ionic liquid.

(Thermoelectric semiconductor fine particles)
The fine particles of the thermoelectric semiconductor can be obtained by pulverizing the above-described inorganic thermoelectric semiconductor material to a predetermined size with a fine pulverizer or the like.

The blending amount of the thermoelectric semiconductor fine particles in the thermoelectric semiconductor composition is preferably 30 to 99% by mass. More preferably, it is 50 to 96% by mass, and still more preferably 70 to 95% by mass. If the thermoelectric semiconductor particles are within the above range, the absolute value of the Seebeck coefficient is large, the decrease in electrical conductivity is suppressed, and only the thermal conductivity is reduced, so that high thermoelectric performance is exhibited and sufficient film strength is obtained. A film having flexibility is preferably obtained.

The average particle diameter of the thermoelectric semiconductor fine particles is preferably 10 nm to 200 μm, more preferably 10 nm to 30 μm, still more preferably 50 nm to 10 μm, and particularly preferably 1 to 6 μm. If it is in the said range, uniform dispersion | distribution will become easy and electrical conductivity can be made high.

The method for obtaining thermoelectric semiconductor fine particles by pulverizing thermoelectric semiconductor material is not particularly limited. Jet mill, ball mill, bead mill, colloid mill, conical mill, disk mill, edge mill, milling mill, hammer mill, pellet mill, wheelie mill, roller What is necessary is just to grind | pulverize to predetermined size by well-known fine grinding | pulverization apparatuses, such as a mill.

The average particle size of the thermoelectric semiconductor fine particles was obtained by measuring with a laser diffraction particle size analyzer (CILAS, type 1064), and was the median value of the particle size distribution.

Further, the fine particles of the thermoelectric semiconductor used in the thermoelectric semiconductor composition are preferably those that have been subjected to an annealing treatment (hereinafter also referred to as annealing treatment A). By performing the annealing treatment A, the thermoelectric semiconductor fine particles have improved crystallinity, and further, the surface oxide film of the thermoelectric semiconductor fine particles is removed, so that the Seebeck coefficient of the thermoelectric material is increased and the thermoelectric performance index is further increased. Can be improved. Annealing treatment A is not particularly limited, but before preparing the thermoelectric semiconductor composition, an inert gas atmosphere such as nitrogen or argon in which the gas flow rate is controlled so as not to adversely affect the fine particles of the thermoelectric semiconductor. It is preferably carried out for several minutes to several tens of hours at a temperature below the melting point of the fine particles under a reducing gas atmosphere such as hydrogen or under vacuum conditions. Specifically, although it depends on the fine particles of the thermoelectric semiconductor used, it is usually preferably carried out at 100 to 1500 ° C. for several minutes to several tens of hours.

(Ionic liquid)
The ionic liquid contained in the thermoelectric semiconductor composition is a molten salt formed by combining a cation and an anion, and refers to a salt that can exist as a liquid in a wide temperature range of −50 to 500 ° C. Ionic liquids have features such as extremely low vapor pressure, non-volatility, excellent thermal stability and electrochemical stability, low viscosity, and high ionic conductivity. Therefore, it is possible to effectively suppress a reduction in electrical conductivity between the fine particles of the thermoelectric semiconductor as a conductive auxiliary agent. In addition, since the ionic liquid exhibits high polarity based on the aprotic ionic structure and is excellent in compatibility with the heat-resistant resin, the electric conductivity of the thermoelectric material can be made uniform.

Known or commercially available ionic liquids can be used. For example, nitrogen-containing cyclic cation compounds such as pyridinium, pyrimidinium, pyrazolium, pyrrolidinium, piperidinium, imidazolium and their derivatives; tetraalkylammonium-based amine cations and their derivatives; phosphonium, trialkylsulfonium, tetraalkylphosphonium, etc. Phosphine cations and derivatives thereof; cation components such as lithium cations and derivatives thereof; chloride ions such as Cl ⁻ , AlCl ₄ ⁻ , Al ₂ Cl ₇ ⁻ , ClO ₄ ⁻ , bromide ions such as Br ⁻ , I ⁻ iodide etc., PF ₆ ^- fluoride ions, F _{(HF) n,} such as ^- such as halide anions _{^{of, NO 3 -, CH 3 COO}} -, CF 3 COO -, CH 3 SO 3 -, CF 3 SO ₃ ^-, (FSO ₂ ) ₂ N ⁻ , (CF ₃ SO ₂ ) ₂ N ⁻ , (CF ₃ SO ₂ ) ₃ C ⁻ , AsF ₆ ⁻ , SbF ₆ ⁻ , NbF ₆ ⁻ , TaF ₆ ⁻ , F (HF) _n ⁻ , (CN ) ₂ N ⁻ , C ₄ F ₉ SO ₃ ⁻ , (C ₂ F ₅ SO ₂ ) ₂ N ⁻ , C ₃ F ₇ COO ⁻ , (CF ₃ SO ₂ ) (CF ₃ CO) N ^{− and the} like The thing comprised from is mentioned.

Among the above ionic liquids, from the viewpoints of high temperature stability, compatibility with thermoelectric semiconductor fine particles and resin, suppression of decrease in electrical conductivity of thermoelectric semiconductor fine particle gaps, the cation component of the ionic liquid is pyridinium cation and It is preferable to include at least one selected from the derivatives, imidazolium cations and derivatives thereof. The anion component of the ionic liquid preferably contains a halide anion, and more preferably contains at least one selected from Cl ⁻ , Br ⁻ and I ⁻ .

Specific examples of ionic liquids in which the cation component includes a pyridinium cation and derivatives thereof include 4-methyl-butylpyridinium chloride, 3-methyl-butylpyridinium chloride, 4-methyl-hexylpyridinium chloride, 3-methyl-hexylpyridinium Chloride, 4-methyl-octylpyridinium chloride, 3-methyl-octylpyridinium chloride, 3,4-dimethyl-butylpyridinium chloride, 3,5-dimethyl-butylpyridinium chloride, 4-methyl-butylpyridinium tetrafluoroborate, 4- Methyl-butylpyridinium hexafluorophosphate, 1-butyl-4-methylpyridinium bromide, 1-butyl-4-methylpyridinium hexafluorophosphate, Chill-4-methylpyridinium iodide and the like. Of these, 1-butyl-4-methylpyridinium bromide, 1-butyl-4-methylpyridinium hexafluorophosphate, and 1-butyl-4-methylpyridinium iodide are preferable.

Specific examples of ionic liquids in which the cation component includes an imidazolium cation and derivatives thereof include [1-butyl-3- (2-hydroxyethyl) imidazolium bromide], [1-butyl-3- (2 -Hydroxyethyl) imidazolium tetrafluoroborate], 1-ethyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium bromide, 1-butyl-3-methylimidazolium chloride, 1-hexyl-3 -Methylimidazolium chloride, 1-octyl-3-methylimidazolium chloride, 1-decyl-3-methylimidazolium chloride, 1-decyl-3-methylimidazolium bromide, 1-dodecyl-3-methylimidazolium chloride, 1-Tetradecyl-3-methylimida 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-hexyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3 -Methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium hexafluorophosphate, 1-methyl-3-butylimidazolium methyl sulfate, 1,3-dibutylimidazolium methyl sulfate, and the like. Of these, [1-butyl-3- (2-hydroxyethyl) imidazolium bromide] and [1-butyl-3- (2-hydroxyethyl) imidazolium tetrafluoroborate] are preferable.

The ionic liquid preferably has an electric conductivity of 10 ⁻⁷ S / cm or more, and more preferably 10 ⁻⁶ S / cm or more. If the ionic conductivity is in the above range, it is possible to effectively suppress a reduction in electrical conductivity between the thermoelectric semiconductor particles as a conductive auxiliary agent.

In addition, the above ionic liquid preferably has a decomposition temperature of 300 ° C. or higher. If the decomposition temperature is within the above range, the effect as a conductive additive can be maintained even when annealing treatment B is applied to the film-like body of the thermoelectric semiconductor composition, as will be described later.

Further, the ionic liquid has a mass reduction rate at 300 ° C. by thermogravimetry (TG) of preferably 10% or less, more preferably 5% or less, and further preferably 1% or less. . When the mass reduction rate is in the above range, as described later, even when the film-like body of the thermoelectric semiconductor composition is subjected to the annealing treatment B, the effect as a conductive additive can be maintained.

The blending amount of the ionic liquid in the thermoelectric semiconductor composition is preferably 0.01 to 50% by mass, more preferably 0.5 to 30% by mass, and still more preferably 1.0 to 20% by mass. When the blending amount of the ionic liquid is within the above range, a decrease in electrical conductivity is effectively suppressed, and a film having high thermoelectric performance can be obtained.

(Heat resistant resin)
The heat-resistant resin used in the thermoelectric semiconductor composition serves to increase the flexibility of the thermoelectric material by acting as a binder between the thermoelectric semiconductor fine particles. The heat-resistant resin is not particularly limited. However, when the thermoelectric semiconductor composition is crystal-grown by annealing the film-like body of the thermoelectric semiconductor composition, the mechanical strength and thermal conductivity as the resin, etc. A heat-resistant resin that maintains the physical properties of these materials without being impaired is used.

Examples of the heat resistant resin include polyamide resin, polyamideimide resin, polyimide resin, polyetherimide resin, polybenzoxazole resin, polybenzimidazole resin, epoxy resin, and copolymers having a chemical structure of these resins. Can be mentioned. The heat resistant resins may be used alone or in combination of two or more. Among these, polyamide resin, polyamideimide resin, polyimide resin, and epoxy resin are preferable because they have higher heat resistance and do not adversely affect crystal growth of the thermoelectric semiconductor fine particles in the thin film, and are excellent in flexibility. From the viewpoint, polyamide resin, polyamideimide resin, and polyimide resin are more preferable. When a polyimide film is used as the above-mentioned support, a polyimide resin is more preferable as the heat-resistant resin in terms of adhesion to the polyimide film. In the present embodiment, the polyimide resin is a general term for polyimide and its precursor.

The heat-resistant resin preferably has a decomposition temperature of 300 ° C. or higher. If the decomposition temperature is within the above range, as will be described later, even when annealing treatment B is performed on the film-like body of the thermoelectric semiconductor composition, the function as a binder is not lost and the flexibility of the thermoelectric material is maintained. Can do.

In addition, the heat-resistant resin preferably has a mass reduction rate at 300 ° C. of 10% or less, more preferably 5% or less, and further preferably 1% or less by thermogravimetry (TG). If the mass reduction rate is in the above range, as will be described later, even when the thermoelectric semiconductor composition film is subjected to the annealing treatment B, the function as a binder is not lost and the flexibility of the thermoelectric material is maintained. be able to.

The blending amount of the heat resistant resin in the thermoelectric semiconductor composition is preferably 0 to 40% by mass, more preferably 0.5 to 20% by mass, and further preferably 1 to 20% by mass. When the blending amount of the heat resistant resin is within the above range, a film having both high thermoelectric performance and film strength can be obtained.

In addition to the thermoelectric semiconductor fine particles, the heat-resistant resin and the ionic liquid, the thermoelectric semiconductor composition may further include a dispersant, a film-forming aid, a light stabilizer, an antioxidant, a tackifier, a plasticizer, Other additives such as a colorant, a resin stabilizer, a filler, a pigment, a conductive filler, a conductive polymer, and a curing agent may be included. These additives can be used alone or in combination of two or more.

The method for preparing the thermoelectric semiconductor composition is not particularly limited. Thermoelectric semiconductor fine particles, ionic liquid, and heat-resistant resin are necessary by a known method such as ultrasonic homogenizer, spiral mixer, planetary mixer, disperser, hybrid mixer, etc. Depending on the above, other additives and a solvent may be added and mixed and dispersed to prepare the thermoelectric semiconductor composition.

Examples of the solvent include solvents such as toluene, ethyl acetate, methyl ethyl ketone, alcohol, tetrahydrofuran, methyl pyrrolidone, and ethyl cellosolve. These solvents may be used alone or in a combination of two or more. The solid content concentration of the thermoelectric semiconductor composition is not particularly limited as long as the composition has a viscosity suitable for coating.

The film-like body of the thermoelectric semiconductor composition can be formed by applying the thermoelectric semiconductor composition onto a support and drying, as described in the method for producing a thermoelectric material of Example 5 described later. Thus, by forming, a large-area thermoelectric material can be easily obtained at low cost.

The thickness of the film-like body of the thermoelectric semiconductor composition is not particularly limited, but is preferably 100 nm to 200 μm, more preferably 300 nm to 150 μm, and still more preferably 5 to 150 μm from the viewpoint of thermoelectric performance and film strength.

The thermoelectric semiconductor composition is further subjected to an annealing treatment (hereinafter sometimes referred to as “annealing treatment B”) after the thin film is formed. By performing the annealing treatment B, the thermoelectric performance can be stabilized and the thermoelectric semiconductor fine particles in the thin film can be crystal-grown, and the thermoelectric performance can be further improved. Although the annealing treatment B is not particularly limited, it is usually performed at 100 to 500 ° C. under an inert gas atmosphere such as nitrogen or argon, a reducing gas atmosphere such as hydrogen, or a vacuum condition where the gas flow rate is controlled. For several minutes to several tens of hours. The processing conditions of the annealing process B can be changed depending on the resin used, the heat resistant temperature of the ionic fluid, and the like.

As the organic thermoelectric material, at least one selected from polyanilines, polypyrroles or polythiophenes, and derivatives thereof is preferably used.
Polyanilines are high molecular weight compounds of compounds in which the 2-position, 3-position or N-position of aniline is substituted with an alkyl group having 1 to 18 carbon atoms, an alkoxy group, an aryl group, a sulfonic acid group or the like. Methyl aniline, poly 3-methyl aniline, poly 2-ethyl aniline, poly 3-ethyl aniline, poly 2-methoxy aniline, poly 3-methoxy aniline, poly 2-ethoxy aniline, poly 3-ethoxy aniline, poly N-methyl aniline Poly N-propyl aniline, poly N-phenyl-1-naphthyl aniline, poly 8-anilino-1-naphthalene sulfonic acid, poly 2-aminobenzene sulfonic acid, poly 7-anilino-4-hydroxy-2-naphthalene sulfonic acid Etc.
Polypyrroles are high molecular weight compounds of compounds in which 1-position, 3-position or 4-position of pyrrole is substituted with an alkyl group or alkoxy group having 1 to 18 carbon atoms, such as poly 1-methyl pyrrole, poly 3-pyrrole. Examples thereof include methyl pyrrole, poly 1-ethyl pyrrole, poly 3-ethyl pyrrole, poly 1-methoxy pyrrole, 3-methoxy pyrrole, poly 1-ethoxy pyrrole, poly 3-ethoxy pyrrole and the like.
Polythiophenes are high molecular weight compounds of compounds in which the 3-position or 4-position of thiophene is substituted with an alkyl group or alkoxy group having 1 to 18 carbon atoms, such as poly-3-methylthiophene, poly-3-ethylthiophene, poly Examples thereof include polymers such as 3-methoxythiophene, poly-3-ethoxythiophene, and poly3,4-ethylenedioxythiophene (PEDOT).
Examples of the derivatives of polyanilines, polypyrroles or polythiophenes include these dopant bodies.
As dopants, halide ions such as chloride ion, bromide ion and iodide ion; perchlorate ion; tetrafluoroborate ion; hexafluoroarsenate ion; sulfate ion; nitrate ion; thiocyanate ion; hexafluoride Silicate ion; Phosphate ion such as phosphate ion, phenyl phosphate ion, hexafluorophosphate ion; trifluoroacetate ion; alkylbenzenesulfonate ion such as tosylate ion, ethylbenzenesulfonate ion, dodecylbenzenesulfonate ion; methylsulfone Alkyl sulfonate ions such as acid ions and ethyl sulfonate ions; or polyacrylate ions, polyvinyl sulfonate ions, polystyrene sulfonate ions (PSS), poly (2-acrylamido-2-methylpropane sulfonate) ions Polymers such as ions such emissions can be mentioned, which may be used in combination singly or two or more.
Among these, as a dopant, high conductivity can be easily adjusted, and since it has a hydrophilic skeleton useful for easy dispersion when it is made into an aqueous solution, polyacrylate ions, polyvinyl sulfonate ions, Polymer ions such as polystyrene sulfonate ion (PSS) and poly (2-acrylamido-2-methylpropane sulfonate) ion are preferred, and polystyrene sulfonate ion (PSS) which is a water-soluble and strongly acidic polymer is more preferred.

As the derivative of the polyaniline, polypyrrole or polythiophene, a derivative of polythiophene is preferable, and among them, a mixture of poly (3,4-ethylene oxide thiophene) and polystyrenesulfonate ion as a dopant (hereinafter referred to as “PEDOT: May be described as “PSS”).
Methods for forming a thermoelectric conversion layer using the above materials include various coatings such as dip coating, spin coating, spray coating, gravure coating, die coating, and doctor blade, and wet processes such as electrochemical deposition, screen printing and Various types of printing such as ink-jet printing can be mentioned and appropriately selected.

The thickness of the thermoelectric conversion layer 22 formed from an organic thermoelectric material is preferably 5 nm or more and 1000 nm or less, and more preferably 30 nm or more and 300 nm or less. If it is less than 5 nm, the electrical resistance of the film becomes too high and thermoelectric conversion may not be possible. On the other hand, when the thickness exceeds 1000 nm, the film forming process cost becomes excessive, and the cost effectiveness deteriorates, which is not preferable.
The thermoelectric conversion layer 22 may be a single layer of the inorganic thermoelectric material or the organic polymer compound as long as it falls within the range of the rated capacity, or the kind of the inorganic thermoelectric material or the organic polymer compound. A structure in which layers formed using different layers are stacked may be used.

In the exhaust heat recovery sheet according to the present embodiment, the various thermoelectric materials described above can be used. When a plurality of thermoelectric materials are used, the comparison of the rated capacities is made with the sum of the thermoelectric materials.

(Electrode layer)
The electrode layer 23 is formed from a conductive material. As a conductive material, a material having a relatively small work function is preferable. For example, metals such as platinum, gold, silver, aluminum, indium, chromium, copper, tin, nickel, metal oxides of these metals, or metal alloys In addition, a carbon nanotube or a composite of the carbon nanotube and the metal, metal oxide, or alloy can be given. The thickness of the electrode layer 23 is preferably 0.02 to 100 μm, and particularly preferably 0.03 to 10 μm.

<Method for manufacturing thermoelectric conversion device>
Next, a method for manufacturing the thermoelectric conversion device 20 will be described.
The thermoelectric conversion layer 22 is formed on the surface of the base material 10 using the thermoelectric material described above. In the case of using the inorganic thermoelectric material described above, the thermoelectric conversion layer 22 can be formed by flash evaporation, vacuum arc vapor deposition, screen printing, coating, or the like of the inorganic thermoelectric material, for example.
In addition, when using the organic thermoelectric material described above, an aqueous dispersion or solution (coating solution) of an organic polymer compound is used for dip coating, spin coating, spray coating, gravure coating, die coating, doctor blade, etc. The thermoelectric conversion layer 22 can be formed on the substrate 10 by various coatings, ink jet printing, or the like. When the thermoelectric conversion layer 22 is made of a thermoelectric semiconductor composition containing fine particles of a thermoelectric semiconductor, a heat resistant resin, and an ionic liquid, an annealing process B is performed.
Subsequently, an electrode layer 23 is further formed on the base material 10 on which the pattern of the thermoelectric conversion layer 22 is formed using a conductive material. For the formation of the electrode layer 23, a dry process such as PVD (physical vapor deposition) such as vacuum deposition, sputtering, ion plating, or CVD (chemical vapor deposition) such as thermal CVD or atomic layer deposition (ALD), Alternatively, various processes such as dip coating, spin coating, spray coating, bar coating, gravure coating, die coating, and doctor blade, and wet processes such as electrochemical deposition can be applied.
Through the above steps, the thermoelectric conversion device 20 can be manufactured.

[Other aspects of exhaust heat recovery sheet]
Another aspect of the exhaust heat recovery sheet according to the embodiment of the present invention will be described. FIG. 3 is an external perspective view of the exhaust heat recovery sheet 1C. 4A is a perspective view showing one pattern film 30 constituting the exhaust heat recovery sheet 1C, and FIG. 4B is a perspective view showing the other pattern film 40 opposed to the pattern film 30. FIG. It is.
The exhaust heat recovery sheet 1C includes a pattern film 30 and a pattern film 40, and a so-called π-type thermoelectric conversion module is formed. The pattern film 30 shown in FIG. 4A includes a base material 31, a p-type thermoelectric element 32, an n-type thermoelectric element 33, and a lower electrode 34. The lower electrode 34 includes an electrode 34a that electrically connects the p-type thermoelectric element 32 and the n-type thermoelectric element 33, and current collecting electrodes 34b and 34c. In the pattern film 30, a lower electrode 34 is formed in a predetermined pattern on a base material 31. Furthermore, the p-type thermoelectric element 32 and the n-type thermoelectric element 33 are alternately formed on the lower electrode 34 so as to be connected in series in the direction of the dotted arrow in FIG.
A pattern film 40 shown in FIG. 4B includes a base material 41 and an upper electrode 42. The pattern film 40 is overlaid on the pattern film 30 so that the upper electrode 42 connects the p-type thermoelectric element 32 and the n-type thermoelectric element 33 formed on the pattern film 30 in series, and a conductive adhesive (FIG. Are bonded to each other.
In the exhaust heat recovery sheet 1C, the p-type thermoelectric element 32, the n-type thermoelectric element 33, the lower electrode 34, and the upper electrode 42 constitute a thermoelectric conversion device. The p-type thermoelectric element 32 and the n-type thermoelectric element 33 correspond to the thermoelectric conversion layers in FIGS. 1 and 2. In the exhaust heat recovery sheet 1 </ b> C, the direction in which electricity flows through the p-type thermoelectric element 32 and the n-type thermoelectric element 33, which are thermoelectric conversion layers, is arranged so as to intersect the planes of the base material 31 and the base material 41.
In the case of the exhaust heat recovery sheet 1 </ b> C, the thickness of the base material in the following formula corresponds to the thickness of the base material 31 or 41 that is in contact with the heat source or close to the heat source.
{(Heat conductivity of heat source) × (thickness in the direction in which the temperature gradient of the heat source is generated)} + {(heat conductivity of the base material) × (thickness of the base material)}> {(thermal conductivity of thermoelectric material) ) × (thickness of the thermoelectric conversion layer)}

As the conductive adhesive, for example, a thermosetting resin or a thermoplastic resin in which a conductive filler is dispersed, a thermosetting resin or a thermoplastic resin in which a conductive polymer is dispersed, or the like is used. Conductive fillers include carbon fiber, carbon nanofiber, carbon black, multi-walled carbon nanotube, single-walled carbon nanotube, carbon compounds such as fullerene, gold, silver, copper, aluminum and other metals, silicon oxide, titanium oxide, zirconium oxide And metal oxides such as ITO. Examples of the conductive polymer include polyaniline, polypyrrole, polythiophene, or polythiophene doped with polystyrene sulfonic acid.

[Aspect of power storage unit]
An aspect of the power storage unit connected to the exhaust heat recovery sheet according to the present invention will be described. The power storage unit includes a secondary battery, a capacitor, and the like. The secondary battery may be any battery that can store electricity, for example, lithium battery, lithium polymer battery, lithium ion battery, nickel metal hydride battery, nickel-cadmium battery, organic radical battery, lead storage battery, air secondary battery, nickel zinc battery, A silver zinc battery etc. are mentioned. Examples of the capacitor include an electric double layer capacitor and a lithium ion capacitor. The exhaust heat recovery sheet may have a control circuit that controls the storage operation of the electrical energy obtained from the thermoelectric conversion device to the storage unit.

Next, although this invention is demonstrated in detail using an Example, this invention is not limited to these examples.
[Evaluation methods]
The following method evaluated the thermoelectric performance of the waste heat recovery sheet produced in the examples and comparative examples described later.
<Thermal conductivity>
The 3ω method was used for the measurement of thermal conductivity.
<Temperature difference>
Using a cooling device that combines a chiller (manufactured by ASONE Co., Ltd., “LTCi-150H”) and a water-cooled cooler (manufactured by Takagi Seisakusho Co., Ltd., “P-200S”), It was kept at 300K. Further, the other surface of the exhaust heat recovery sheet was held at 350 K with a hot plate (“THI-1000” manufactured by ASONE CORPORATION). In this state, the temperature above and below the power generation layer was measured with a measuring device in which a K-type thermocouple and a data logger (Eto Denki Co., Ltd., “Kadak 3”) were combined, and the temperature difference was calculated.
<Output voltage>
It was measured with a potentiometer (manufactured by Hioki Electric Co., Ltd., Digital Hitester 3801-50).

[Examples and Comparative Examples]
An exhaust heat recovery sheet was prepared as follows.
<Example 1>
(Production of exhaust heat recovery sheet)
PEDOT: PSS (AGFA), an organic thermoelectric material, is formed on the surface of a polyimide film (manufactured by Toray DuPont Co., Ltd., “Kapton 200H”, thickness 50 μm, thermal conductivity 0.16 W / m · K). A thermoelectric conversion layer was formed by using an inkjet printer (“NanoPrinter-300” manufactured by Microjet Co., Ltd.) with “S-305” manufactured by Material Co., Ltd., and a thermal conductivity of 0.3 W / m · K. . After formation, it was dried at 150 ° C. in the atmosphere. Subsequently, an electrode layer was formed using copper as a conductive material by a vacuum deposition method, and an exhaust heat recovery sheet a having the structure of the exhaust heat recovery sheet 1A shown in FIG. 1 was produced. The total thickness of the exhaust heat recovery sheet a was 50.2 μm.
As a heat source, an aluminum plate (heat sink type 1; thermal conductivity 236 W / m · K, thickness 1 mm) was used. In the exhaust heat recovery sheet a, the current direction of the thermoelectric conversion layer is arranged in parallel to the plane of the substrate. The exhaust heat recovery sheet a was arranged so that the current direction of the thermoelectric conversion layer intersected the direction in which the temperature gradient of the heat source occurred.
The specimen was heated by the method described above, and the temperature difference generated in the exhaust heat recovery sheet a was measured. Moreover, the output voltage obtained was measured. The results are shown in Table 1.

<Example 2>
On the surface of a polyimide film (“Kapton 200H” manufactured by Toray DuPont Co., Ltd., thickness 50 μm, thermal conductivity 0.16 W / m · K) used as a base material, with an inorganic thermoelectric material via a shadow mask A p-type bismuth telluride (manufactured by High Purity Chemical Co., Ltd., thermal conductivity 1.5 W / m · K) was formed using an arc plasma deposition apparatus (manufactured by ULVAC-RIKO Co., Ltd., “APD-S”). . Subsequently, n-type bismuth telluride (manufactured by Koyo Chemical Co., Ltd., thermal conductivity 1.5 W / m · K) was deposited in the same manner. Thereafter, an electrode layer was formed using copper as a conductive material by using a vacuum evaporation apparatus, and an exhaust heat recovery sheet b having the structure of a pn type exhaust heat recovery sheet 1B shown in FIG. 2 was produced. The total thickness of the exhaust heat recovery sheet b was 50.2 μm.
As the heat source, a copper plate (heat sink type 2; thermal conductivity 386 W / m · K, thickness 1 mm) was used. In the exhaust heat recovery sheet b, the current direction of the thermoelectric conversion layer is arranged in parallel to the plane of the substrate. The exhaust heat recovery sheet b was arranged so that the current direction of the thermoelectric conversion layer intersected the direction in which the temperature gradient of the heat source occurred. The specimen was heated by the method described above, and the temperature difference generated in the exhaust heat recovery sheet b was measured. Moreover, the output voltage obtained was measured. The results are shown in Table 1.

<Example 3>
As an inorganic thermoelectric material, p-type manganese silicide (manufactured by Koyo Chemical Co., Ltd., thermal conductivity 10 W / m · K), and n-type magnesium silicide (manufactured by Koyo Chemical Co., Ltd., thermal conductivity 8 W / m · K) Pn type exhaust heat shown in FIG. 2 in the same manner as in Example 2 except that the film was formed using an MBE film forming apparatus (“ST-LMBE” manufactured by Pascal Co., Ltd.). A recovery sheet c was produced. A copper plate (thermal conductivity 386 W / m · K, thickness 1 mm) was used as a heat source.
In the exhaust heat recovery sheet c, the current direction of the thermoelectric conversion layer is arranged in parallel to the plane of the substrate. The exhaust heat recovery sheet c was arranged so that the current direction of the thermoelectric conversion layer intersected the direction in which the temperature gradient of the heat source occurred. The specimen was heated by the method described above, and the temperature difference generated in the exhaust heat recovery sheet c was measured. Moreover, the output voltage obtained was measured. The results are shown in Table 1.

<Example 4>
As an inorganic thermoelectric material, p-type Fe ₂ VAl (manufactured by High Purity Chemical Co., Ltd., thermal conductivity 15 W / m · K) and n-type Fe ₂ VAl (manufactured by Koyo Chemical Co., Ltd., thermal conductivity 20 W / pn type exhaust heat shown in FIG. 2 in the same manner as in Example 2, except that the film was formed using a sputtering film forming apparatus (“i-sputter” manufactured by ULVAC, Inc.) using m · K). A recovery sheet d was produced. A copper plate (thermal conductivity 386 W / m · K, thickness 1 mm) was used as a heat source.
In the exhaust heat recovery sheet d, the current direction of the thermoelectric conversion layer is arranged in parallel to the plane of the substrate. The exhaust heat recovery sheet d was arranged so that the current direction of the thermoelectric conversion layer intersected the direction in which the temperature gradient of the heat source occurred. The specimen was heated by the method described above, and the temperature difference generated in the exhaust heat recovery sheet d was measured. Moreover, the output voltage obtained was measured. The results are shown in Table 1.

<Example 5>
(Method for producing thermoelectric semiconductor fine particles)
A p-type bismuth telluride Bi _0.4 Te ₃ Sb _1.6 (manufactured by High-Purity Chemical Laboratory, particle size: 180 μm), which is a bismuth-tellurium-based thermoelectric semiconductor material, is converted into a planetary ball mill (French Japan, Premium line P). The thermoelectric semiconductor fine particles T1 having an average particle diameter of 1.2 μm were prepared by pulverizing under a nitrogen gas atmosphere using −7). The thermoelectric semiconductor fine particles obtained by pulverization were subjected to particle size distribution measurement using a laser diffraction particle size analyzer (CILAS, model 1064).
In addition, n-type bismuth telluride Bi ₂ Te ₃ (manufactured by High Purity Chemical Laboratory, particle size: 180 μm), which is a bismuth-tellurium-based thermoelectric semiconductor material, is pulverized in the same manner as described above, and thermoelectric semiconductor fine particles having an average particle size of 1.4 μm T2 was produced.

(1) Production of thermoelectric semiconductor composition The fine particles T1 (90 parts by mass) of the obtained bismuth-tellurium-based thermoelectric semiconductor material, polyamic acid (5 parts by mass) which is a polyimide precursor as a heat-resistant resin, and ionic liquid 1 As 1-butyl-3- (2-hydroxyethyl) imidazolium bromide (electric conductivity: 3.5 × 10 ⁻⁵ S / cm) (5 parts by mass), and mixing and dispersing them to obtain p-type A coating solution P made of a thermoelectric semiconductor composition containing fine particles T1 of bismuth telluride was prepared.
As the polyamic acid, “poly (pyromellitic dianhydride-co-4,4′-oxydianiline) solution” manufactured by Sigma-Aldrich, solvent: methylpyrrolidone, solid content concentration: 15% by mass, 300 ° C. The mass reduction rate at 0.9% was 0.9%.
A coating liquid N made of a thermoelectric semiconductor composition containing fine particles T2 of n-type bismuth telluride was prepared in the same amount as described above except that the fine particles T1 were changed to fine particles T2.
The coating liquid P prepared in (1) is applied by screen printing onto a polyimide film (trade name “Kapton 200H”, thickness 50 μm, manufactured by Toray DuPont Co., Ltd.), which is a base material, at a temperature of 150 ° C. for 10 minutes. The film was dried under an argon atmosphere to form a thin film having a thickness of 10 μm. Next, the obtained thin film was heated at a heating rate of 5 K / min in a mixed gas atmosphere in which the ratio of hydrogen to argon was hydrogen: argon = 5% by volume: 95% by volume, and the temperature was 415 ° C. By holding for 1 hour and performing annealing treatment B after thin film formation, the microparticles of the thermoelectric semiconductor material were grown to produce a p-type thermoelectric conversion material. In the same manner, an n-type thermoelectric material was produced using the coating liquid N prepared in (1).

(2) Production of π-type thermoelectric conversion module As shown in FIG. 4A, a polyimide film as a base material (trade name “Kapton 200H” manufactured by Toray DuPont Co., Ltd., thickness 50 μm, thermal conductivity 0.16 W / m -K) A lower electrode was formed on the upper surface by screen printing. Furthermore, using the coating liquid P and the coating liquid N prepared in (1), the pattern of the p-type thermoelectric element and the n-type thermoelectric element shown in FIG. Then, it was dried in an argon gas atmosphere for 10 minutes, and a thin film was formed so that each thickness of the p-type thermoelectric element and the n-type thermoelectric element was 100 μm.
The obtained thin film is heated at a heating rate of 5 K / min in an argon gas atmosphere, and annealing treatment B is performed at 415 ° C. for 1 hour to grow microparticles of thermoelectric semiconductor material to form a p-type. A pattern film provided with a thermoelectric element and an n-type thermoelectric element was produced.
Next, on the polyimide film (made by Toray DuPont, trade name “Kapton”, thickness 50 μm) as the base material, the pattern of the upper electrode is applied by screen printing as shown in FIG. A pattern film was prepared.
Conductive adhesives (made by Nihon Solder Co., Ltd.) are used so that the pattern films are electrically connected in series with a p-type thermoelectric element and an n-type thermoelectric element and thermally connected in parallel. The waste heat recovery sheet e having the structure of the exhaust heat recovery sheet 1C shown in FIG. 3 was produced by pasting and bonding via the name “ECA100”, thickness 20 μm). The same aluminum plate as used in Example 1 was used as a heat source.
The exhaust heat recovery sheet e is disposed so that the current direction of the thermoelectric conversion layer intersects the plane of the substrate. The exhaust heat recovery sheet e was arranged so that the current direction of the thermoelectric conversion layer was the same as the direction in which the temperature gradient of the heat source was generated. The specimen was heated by the method described above, and the temperature difference generated in the exhaust heat recovery sheet e was measured. Moreover, the output voltage obtained was measured. The results are shown in Table 1.

<Comparative Example 1>
Copper column (thermal conductivity) as p-type thermoelectric material on the surface of polyimide film (“Kapton 200H” manufactured by Toray DuPont Co., Ltd., thickness 50 μm, thermal conductivity 0.16 W / m · K) used as a base material 386 W / m · K) cut to a thickness of 2 mm, and then a nickel column (thermal conductivity 91 W / m · K) as an n-type thermoelectric material cut to a thickness of 6 mm Arranged. Then, the electrode layer was formed using copper as an electroconductive material using the vacuum evaporation system, and the thermoelectric conversion device was produced.
The same aluminum plate as used in Example 1 was used as a heat source. The specimen was heated by the method described above, and the temperature difference generated in the thermoelectric conversion device was measured. Moreover, the output voltage obtained was measured. The results are shown in Table 1.

[Evaluation results]
According to the specimens of Examples 1 to 5, heat can be efficiently transferred under a device configuration that satisfies the provisions of the present invention, and heat energy can be converted into electrical energy regardless of the module structure. all right.

The waste heat recovery sheet of the present invention was originally released by installing it in a pipe, a casing of a device that generates heat, etc., from which a living waste heat and industrial waste heat are obtained, by a thermoelectric conversion device formed in a sheet shape. Part of thermal energy can be regenerated into electrical energy.

1A, 1B, 1C Waste heat recovery sheet, 10 base material, 20 thermoelectric conversion device, 22, 22a, 22b thermoelectric conversion layer, 23 electrode layer, 30, 40 pattern film, 31 base material, 32 p-type thermoelectric element, 33 n Type thermoelectric element, 34 lower electrode, 34a electrode, 34b, 34c current collecting electrode, 41 base material, 42 upper electrode

Claims (8)

1. A sheet having a sheet-like base material disposed on at least a part of a heat source, a thermoelectric conversion layer formed on a surface of the base material and formed from a thermoelectric material, and an electrode layer connected to the thermoelectric conversion layer A thermoelectric conversion device,
   The heat conductivity of the heat source, the thickness of the heat source in the direction in which the temperature gradient occurs, the heat conductivity of the substrate, the thickness of the substrate, the heat conductivity of the thermoelectric material, and the thickness of the thermoelectric conversion layer satisfy the following formula: Waste heat recovery sheet.
   {(Heat conductivity of heat source) × (thickness in the direction in which the temperature gradient of the heat source is generated)} + {(heat conductivity of the base material) × (thickness of the base material)}> {(thermal conductivity of thermoelectric material) ) × (thickness of the thermoelectric conversion layer)}
2. The exhaust heat recovery sheet according to claim 1, wherein a current direction of a thermoelectric conversion layer constituting the thermoelectric conversion device is arranged in parallel to a plane of the base material.
3. The exhaust heat recovery sheet according to claim 1, wherein a current direction of a thermoelectric conversion layer constituting the thermoelectric conversion device is arranged so as to intersect a plane of the base material.
4. The exhaust heat recovery sheet according to any one of claims 1 to 3, wherein the thermoelectric material of the thermoelectric conversion device has a thermal conductivity of 30 W / m · K or less.
5. The exhaust heat recovery sheet according to any one of claims 1 to 4, wherein the thermoelectric material of the thermoelectric conversion device is an n-type thermoelectric material.
6. The exhaust heat recovery sheet according to any one of claims 1 to 4, wherein the thermoelectric material of the thermoelectric conversion device is a p-type thermoelectric material.
7. The thermoelectric material of the thermoelectric conversion device is an n-type thermoelectric material and a p-type thermoelectric material, and an n-type thermoelectric conversion layer made of the n-type thermoelectric material and a p-type thermoelectric conversion layer made of the p-type thermoelectric material are the electrodes. The exhaust heat recovery sheet according to any one of claims 1 to 6, wherein the exhaust heat recovery sheet is connected by layers.
8. The exhaust heat recovery sheet according to any one of claims 1 to 7, further comprising a power storage unit that stores electricity, wherein the electrode layer is electrically connected to the power storage unit.

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