JP2019193495A - Friction generator - Google Patents

Abstract

To provide a friction generator exhibiting high generation performance by solving the following problem: a sufficient review has not been made with a point of view that increasing a potential difference increases a charge amount actually poured into an electrode even with the same charging amount, paying attention to that a friction charging layer has a function as a dielectric body which induces a potential difference to the electrode.SOLUTION: The friction generator includes charging members provided to face each other. At least one of the charging members includes an electrode, a dielectric layer and an outermost layer. The dielectric layer includes matrixes and particles. The dielectric constant of the particles is higher than that of the matrixes.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a friction generator.

In recent years, studies have been made on frictional charging generators. The friction generator generates electric energy by causing a current to flow to an external load using a potential difference generated by a charged charge generated during friction between two charged bodies.
The output of the friction generator is determined by the amount of charge generated by friction and the potential difference generated between the electrodes due to the charge.
As a method for increasing the amount of charged electric charge, there have been reported examples of using a composite material as a triboelectric charging layer or laminating. In Patent Document 1, a self-assembled monolayer containing a silane group or a silanol group is provided between an electrode and a triboelectric material layer, so that the surface characteristics of the electrode are changed and generated by friction with the triboelectric material layer. It has been shown to increase the amount of electrical energy.
Non-Patent Document 1 discloses that the charging characteristics of the triboelectric charging layer can be improved by incorporating alumina particles in the triboelectric charging layer.
Non-Patent Document 2 shows that triboelectric power generation was performed using a structure in which a polystyrene layer and a carbon nanotube layer were inserted under a polyvinylidene fluoride layer as a charging layer, and the amount of current increased.

JP, 2006-226276, A

Sequential Infiltration Synthesis of Doped Polymer Films with Tunable Electrical Properties for Efficient Triboelectric Nanogenerator Development, Advanced Materials, 2015, 27 (33), pp 4938-4944 Dynamic Behavior of the Triboelectric Charges and Structural Optimization of the Friction Layer for a Triboelectric Nanogenerator, ACS Nano, 2016,10 (6), pp 6131-6138

  Both prior arts focus on the role of “charging” of the triboelectric charging layer and focus on increasing the charge amount. However, the triboelectric charging layer also has a function as a dielectric that induces a potential difference in the electrode. Focusing on this, even if the charge amount is the same, increasing the potential difference increases the amount of charge that actually flows into the electrode. However, it has not been fully examined from the viewpoint of.

As a result of studying the role of the friction charging layer as a dielectric, the inventor has found that at least one charging member of the friction generator has a dielectric layer and an outermost layer, and the dielectric layer includes a matrix and particles. It has been found that the frictional generator exhibits a high power generation capability because the particles have a dielectric constant higher than that of the matrix.
That is, the gist of the present invention is as follows.

[1] A friction generator including charging members provided to face each other,
At least one of the charging members has an electrode, a dielectric layer, and an outermost layer,
The dielectric layer has a matrix and particles, and the relative dielectric constant of the particles is higher than the relative dielectric constant of the matrix.
[2] The friction generator according to [1], wherein the dielectric layer has a relative dielectric constant (ε _DI ) of 5 or more.
[3] the dielectric layer thickness of d _DI of the the outermost layer of the film thickness and d _Sf, a d _Sf / d _DI <1, friction generator according to [1] or [2].
[4] The friction generator according to any one of [1] to [3], wherein d _DI is 10 μm or more and 500 μm or less.
[5] The frictional generator according to any one of [1] to [4], wherein d _Sf is 1 μm or more and 100 μm or less.
[6] The friction generator according to any one of [1] to [5], wherein the dielectric layer and the outermost layer contain the same polymer.

  ADVANTAGE OF THE INVENTION According to this invention, the friction generator which shows high power generation capability is provided.

  The present invention is a friction power generator including charging members provided so as to face each other, and at least one of the charging members includes an electrode, a dielectric layer, and an outermost layer, and the dielectric layer includes: It has a matrix and particles, and the dielectric constant of the particles is higher than the relative dielectric constant of the matrix.

It is a schematic structure figure of a friction generator concerning a first embodiment of the present invention. It is a schematic block diagram of the friction generator by other embodiment. It is a schematic block diagram of the friction generator by other embodiment.

  The present invention will be described in detail below, but the following description is an example of an embodiment of the present invention, and the present invention is not limited to the following description unless it exceeds the gist. The present invention can be arbitrarily modified and implemented without departing from the scope of the invention.

  The present invention is a friction generator including a charging member provided so as to face each other, and at least one of the charging members includes an electrode, a dielectric layer, and an outermost layer, and the dielectric layer includes a matrix and a dielectric layer. Particles having a relative dielectric constant higher than that of the matrix.

The charging member of the present invention is not particularly limited as long as it has an electrode, a dielectric layer and an outermost layer, but may further have other layers. Moreover, what became the outermost layer because the matrix contained in the dielectric layer is unevenly distributed on the surface also includes the dielectric layer and the outermost layer.
Further, the outermost layer refers to the outermost layer on the other charging member side provided so as to face the charging member.
The charging members provided so as to face each other become positive and negative charging members when performing frictional power generation. The charging member having the electrode, at least one dielectric layer, and the outermost layer may be positive or negative.

The reason why the friction generator of the present invention has a high power generation capacity is not clear, but the following may be considered.
The friction generator has a structure in which a pair of charging members composed of an electrode and a dielectric layer face each other. When the surface of the dielectric layer of the charging member repeats contact and separation, the surface layers are opposite to each other. Charge to polarity. When the dielectric layers are in contact with each other, the electric fields formed by the positive and negative charges cancel each other, so the potential difference between the electrodes outside the dielectric layers is equal. When the dielectric layers are separated from each other, a potential difference is generated between both electrodes. When the two electrodes are electrically connected via a load resistor, charge flows through this connection. The electric charge flows until the potential difference between the electrodes becomes zero, and this flow becomes an electric current. The amount of charge flowing is smaller than the amount of charge accumulated on the surface of the dielectric layer, and follows the following equation.

Here, σ ′ is the amount of charge flowing between the electrodes (conducted charge amount), σ is the amount of charge accumulated on the surface of the charging member (charge amount), d is the gap between the dielectric layers, and t _p is positive The film thickness of the dielectric layer, t _n is the film thickness of the negative dielectric layer, ε _rp is the dielectric constant of the positive dielectric layer, and ε _rn is the dielectric constant of the negative dielectric layer. That is, the thinner the dielectric layer and the higher the dielectric constant of the dielectric layer, the greater the strength of the electric field induced on the electrode by the charge on the surface of the dielectric layer, resulting in a larger amount of charge flowing. It shows that. Therefore, it is considered that the dielectric layer should have a higher dielectric constant. In order to increase the dielectric constant of the dielectric layer, there is a method of dispersing particles having a high dielectric constant in the dielectric layer.
On the other hand, according to the surface potential calculation that we calculated using the electric field analysis simulator PHOTO-VOLT, if there is a distribution of dielectric constant in the high dielectric constant layer, the surface potential becomes non-uniform, The surface potential increases in the vicinity. Such a local high potential region causes a discharge into the air. Since discharge into the air occurs when the discharge limit voltage is exceeded, it is considered that discharge is more likely to occur near a region having a high dielectric constant. On the other hand, when the surface of the high dielectric constant layer on the electrode is covered with a uniform outermost layer having a low dielectric constant, the surface potential becomes uniform, and it is considered that discharge into the air is suppressed.
In addition, the surface of the dielectric layer in which the particles are dispersed is considered to have large irregularities, leading to a reduction in the contact area when the dielectric layers are in contact with each other. The provision of the outermost layer improves the contact area by flattening the surface irregularities and contributes to more effective charging.
Furthermore, the dielectric layer in which the particles are dispersed is hard, and it is considered difficult to be deformed when the dielectric layers come into contact with each other. It is thought that can be formed.

[Dielectric layer]
The dielectric layer of the present invention has a matrix and particles. The particles have a dielectric constant higher than that of the matrix. The dielectric layer of the present invention may have additives other than the matrix and particles.

The ratio of the relative dielectric constant between the matrix and the particles is not particularly limited and can be adjusted as appropriate.
The content and content ratio of the matrix and particles in the dielectric layer are not particularly limited.
The matrix is preferably 10% by volume or more, more preferably 20% by volume or more, preferably 90% by volume or less, and more preferably 80% by volume or less. On the other hand, the particles are preferably 10% by volume or more, more preferably 20% by volume or more, preferably 90% by volume or less, and more preferably 80% by volume or less. By being within these ranges, the effect of increasing the dielectric constant by particles tends to be obtained while maintaining the shape of the film by the matrix.

The film thickness (d _DI ) of the dielectric layer is preferably 10 μm or more, more preferably 20 μm or more. Moreover, Preferably it is 500 micrometers or less, More preferably, it is 200 micrometers or less. By being below the above upper limit value, the electric field induced in the electrode by the charged charge is maintained, and there is a tendency that the decrease in the amount of power generation can be suppressed. Moreover, it exists in the tendency which can suppress that an electrical charge spread | diffuses and reaches | attains and lose | disappears and an electrical short circuit generate | occur | produces because it is more than the said lower limit.

(particle)
Specific examples of the particles of the present invention include metal oxides such as titanium oxide and zinc oxide, and ceramics such as barium titanate.
The relative dielectric constant of the particles is not particularly limited, but is preferably 10 or more, and more preferably 30 or more. Moreover, there is no upper limit and the higher one is preferable. By being in these ranges, the dielectric constant layer tends to be highly dielectric, and the electric field strength induced in the electrode tends to be increased.

(Matrix)
The matrix of the present invention has a function of dispersing particles. The matrix is not particularly limited as long as it is a material capable of forming a film or film in which particles having a high dielectric constant are dispersed, and examples thereof include various polymers. Specifically, fluorine resins such as polydimethylsiloxane (PDMS) and polyvinylidene fluoride, polyolefins such as polyimide, polyvinyl chloride, polystyrene, and polyethylene / polypropylene, polyester resins such as polyethylene terephthalate (PET), polycarbonate resin, and polymethyl Examples thereof include acrylic resins such as methacrylate (PMMA), polyamide resins such as nylon, and cellulose.
The relative dielectric constant of the matrix is not particularly limited and can be adjusted as appropriate.

(Relative permittivity)
The relative dielectric constant (ε _DI ) of the dielectric layer in the present invention is preferably 5 or more, more preferably 8 or more. Moreover, there is no upper limit and the higher one is preferable.
The relative dielectric constant can be calculated from the following equation by forming electrodes on both sides of the layer of the material to be measured to produce a parallel plate capacitor and measuring the capacitance C of the capacitor.
C = ε ₀ · ε _r · A / d
Here, ε _r is the relative dielectric constant, ε ₀ is the vacuum dielectric constant, A is the area of the capacitor, and d is the thickness of the layer of the material to be measured. The capacitance of the capacitor can be measured with an LCR meter, impedance analyzer, or the like.

[Outermost layer]
The outermost layer in the present invention refers to a surface that rubs a charged body during frictional power generation.
The outermost layer of the present invention is not particularly limited as long as it is a chargeable material, and examples thereof include polymers and non-metallic substances. Specifically, for polymers, silicone resins such as polydimethylsiloxane (PDMS);
Fluororesins such as polytetrafluoroethylene (PTFE);
Polyimide;
PVC;
polystyrene;
Polyolefins such as polyethylene and polypropylene;
Polyester resins such as polyethylene terephthalate (PET);
Polycarbonate resin;
Acrylic resins such as polymethyl methacrylate (PMMA);
Polyamide resin such as nylon;
Cellulose.
Nonmetallic materials include oxides such as silica and alumina.

The film thickness (d _Sf ) of the outermost layer is preferably 1 μm or more, more preferably 2 μm or more. Moreover, it is preferably 100 μm or less, more preferably 50 μm or less. By being below the upper limit value, the electric field induced on the electrode by the charged charge is increased, and the power generation tends to be maintained and increased, and by being above the lower limit value, the surface of the dielectric layer There is a tendency to cover evenly.

  The outermost layer is preferably a material that is elastic and easily deforms. Such an outermost layer can be deformed when it comes into contact with the opposing dielectric layer to increase the contact area, thereby contributing to an improvement in charge amount. The Young's modulus of the material used for the outermost layer is preferably 8 GPa or less, more preferably 5 GPa or less.

The relative dielectric constant (ε _Sf ) of the outermost layer is not particularly limited, but is preferably 1 or more, more preferably 1.5 or more. Moreover, although an upper limit is not specifically limited, Preferably it is 8 or less, More preferably, it is 5 or less. The measurement method of the relative dielectric constant of the outermost layer is the same as that of the dielectric layer.

[Combination of dielectric layer and outermost layer]
The combination of the dielectric layer and the outermost layer is not particularly limited as long as the effects of the present invention are not significantly impaired. In the case where the outermost layer is formed directly on the dielectric layer, it is preferable that both layers contain the same polymer because the adhesion between the two layers is increased.

The ratio of the film thickness of the dielectric layer and the outermost layer is not particularly limited, but d _Sf / d _DI <1 and more preferably d because the electrostatic induction effect of the outermost dielectric layer is further improved. It is preferable that _Sf / _dDI <0.2.
Further, the relationship between the dielectric constant of the dielectric layer and the outermost layer is not particularly limited, but it is preferable that ε _DI > ε _Sf .

At least one of the charging members contained in the friction generator of the present invention may have an electrode, at least one dielectric layer, and an outermost layer, and the other charging member (hereinafter referred to as a second charging member). Is not particularly limited as long as it has electrodes. For example, the electrode may also serve as a dielectric layer, and may have an electrode, at least one dielectric layer, and an outermost layer.
The material of the dielectric layer in the second charging member is not particularly limited as long as it is a material having charging properties, and examples thereof include polymers and non-metallic substances.
Specifically, for polymers, fluororesins such as polydimethylsiloxane (PDMS) and polytetrafluoroethylene (PTFE), polyolefins such as polyimide, polyvinyl chloride, polystyrene, and polyethylene / polypropylene, and polyesters such as polyethylene terephthalate (PET). Examples thereof include resins, polycarbonate resins, acrylic resins such as polymethyl methacrylate (PMMA), polyamide resins such as nylon, and cellulose.
Nonmetallic materials include oxides such as silica and alumina.

[electrode]
The electrode contained in the friction generator of the present invention is not particularly limited as long as it is a material having high electrical conductivity, and can be suitably used.
For example, a metal such as aluminum, copper, silver, gold, platinum, iron, chromium, molybdenum, or indium, and alloys of these metals can also be used. As long as it has high electrical conductivity, it does not have to be a metal. For example, a semiconductor material such as doped silicon, a metal oxide such as indium tin oxide (ITO), or a conductive polymer such as PEDOT-PSS can be used.

[Production method of dielectric layer]
The dielectric layer can be produced by various methods for forming a film or thin film in which high dielectric constant particles are dispersed in a matrix. For example, there are a hot press, an extruder, a stretching process, a solution process such as spin coating, bar coating, and die coating.

  The outermost layer can be produced by various methods for forming a thin film on the dielectric layer. For example, solution processes such as spin coating, bar coating, and die coating may be used. Any material that vaporizes by heating in vacuum may be formed by a physical vapor deposition process such as vacuum deposition. Moreover, the outermost layer prepared as a thin film can also be bonded on the dielectric layer via an adhesive layer.

[Other]
The two charging members in the friction generator of the present invention may be provided in a state where an electrode and a charging layer are formed on a certain substrate, respectively. At this time, the electrode and the charging layer are formed on the substrate with the electrode facing the substrate and the layer to be charged facing away from the substrate. Each charging member may be bonded to the substrate via an adhesive layer, or may be directly formed on the substrate. Glass, resin, metal, silicon, or the like can be used for the substrate. When the substrate has conductivity, the substrate may also serve as the electrode of the charging member.

  Hereinafter, although the example of embodiment of this invention is shown using a figure, this invention is not necessarily limited to these forms.

FIG. 1 is a schematic configuration diagram of a friction generator 1 according to an embodiment.
Referring to FIG. 1, the friction generator 1 repeats contact / separation with the first electrode 111, the first charging member 110 having at least one dielectric layer 112 and the outermost layer 113, and the first charging member. The second charging member 120 is charged to the opposite polarity. The second charging member 120 has a second electrode 121 and a dielectric layer 122.

  FIG. 2 is a schematic configuration diagram of a friction generator according to another embodiment. Description of components that are substantially the same as the components in FIG. 1 is omitted.

  Referring to FIG. 2, the friction generator 2 repeats contact and separation with the first electrode 211, the first charging member 210 having at least one dielectric layer 212 and the outermost layer 213, and the first charging member. The second charging member 220 is charged to the opposite polarity. In the second charging member 220, the second electrode 221 also serves as a charging layer.

  FIG. 3 is a schematic configuration diagram of a friction generator according to another embodiment. Description of components that are substantially the same as the components in FIG. 3 is omitted.

  Referring to FIG. 3, the friction generator 3 includes a first charging member 310 and a second charging member 320 that are charged to opposite polarities by repeating contact and separation. The first charging member 310 includes a first electrode 311, at least one dielectric layer 312 and an outermost layer 313. The second charging member 320 includes a second electrode 312, at least one dielectric layer 322, and an outermost layer 323.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited by a following example, unless the summary is exceeded.

<Measurement of film thickness>
In order to estimate the dielectric constant of the material, the value of the film thickness of the dielectric layer is required. In addition, since the output of the friction generator depends on the film thickness of the friction charging layer, information on the film thickness is also necessary to compare the output of different friction generators.
The film thickness of the layer was measured using an electronic micrometer (KG3001A manufactured by Anritsu). The measurement error of this apparatus was 0.1 μm.

(Example 1)
Composition 1 was prepared by dissolving 2.17 g of PMMA in 8.67 g of toluene. A composition 2 was prepared by dispersing 19.5 g of barium titanate particles in 10.84 g of the composition 1. The weight ratio of PMMA to barium titanate in composition 2 is 1: 9. As a substrate, an AlPET film, which is a film in which aluminum is vapor-deposited on a PET film, was used. Aluminum of the AlPET film was used as an electrode when forming a friction generator. The composition 2 was applied onto aluminum of an AlPET film with a bar coater and dried at room temperature for 1 hour or more. Thereby, the layer 1 as a dielectric layer containing high dielectric constant particles was formed.
Next, the composition 1 was applied onto the layer 1 on the previous AlPET film with a bar coater and dried at room temperature for 1 hour or longer to form the layer 2 as the outermost layer. The film was cut to a width of 25 mm, and the AlPET side of the film was attached on a 25 mm × 75 mm slide glass via a double-sided adhesive tape to form the positive charging member 1.
Aluminum was vacuum-deposited on one side of a polytetrafluoroethylene (PTFE) film having a thickness of 100 μm. This aluminum is used as the other electrode in forming the friction generator. The film was cut to a width of 25 mm, and the aluminum film side was stuck on a 25 mm × 75 mm slide glass via a double-sided adhesive tape to form the negative charging member 1.
By making the outermost layer side of the positive charging member 1 and the PTFE film side of the negative charging member 1 face each other so that the contact area is 25 mm × 25 mm, it functions as a friction generator by repeated contact and separation. A friction generator 1 having a power generation area of 25 mm ² was formed.

(Comparative Example 1)
The AlPET side of the AlPET film on which up to layer 1 in Example 1 was formed was attached on a slide glass via a double-sided adhesive tape to form a positive charging member 2. The positively charged member 2 and the same negatively charged member 1 as used in Example 1 were made to face each other in the same manner as in Example 1 to form the friction generator 2.

(Comparative Example 2)
A positive charging member 3 was formed in the same manner as in Comparative Example 1 except that instead of the layer 1 in Comparative Example 1, the layer 2 in which the composition 2 used in Example 1 was formed with a bar coater was used. The positively charged member 3 and the same negatively charged member 1 as used in Example 1 were opposed to each other in the same manner as in Example 1 to form the friction generator 3.

<Measurement of current value of frictional power generation>
The slide glass substrate side of the negative charging member was fixed to the head of the linear actuator with an adhesive tape, and the film side of the negative charging member and the molded body of the positive charging member were placed facing each other. The linear actuator was reciprocated to repeat contact and separation between the film surface of the negative charging member and the surface of the molded body of the positive charging member. At this time, the current flowing between the electrode of the negative charging member and the electrode of the positive charging member was measured with an electrometer (Keithley model 6517). The change over time of the current was monitored by outputting the analog output of the electrometer to an oscilloscope (LeCroy 42Xs), and the peak current at the time of contact was measured.

<Calculation of film thickness correction coefficient>
The output of the friction generator depends on the film thickness of the friction charging layer. In order to compare the output of friction generators with different thicknesses of the frictional power generation layer, a current correction coefficient was calculated in consideration of the film thickness difference. The corrected peak current was calculated by multiplying the current value of each friction generator by the correction coefficient for the corresponding film thickness. This value is shown in Table 1.

<Measurement of relative permittivity>
On the AlPET aluminum electrode, the composition 1 and the composition 2 used in Example 1 were respectively applied by a bar coater to form layers 1 and 2. On these coating layers, an aluminum electrode was vacuum-deposited in a circular shape with a diameter of 1 cm to produce a parallel plate capacitor. The electric capacity of the parallel plate capacitor was measured using an impedance analyzer (Solatron 1296/1260). From the electric capacity and the film thickness, the relative dielectric constant εr of the layer 1 or the layer 2 was estimated according to the following formula.
C = ε ₀ · ε _r · A / d
Here, ε _r is the relative dielectric constant, ε ₀ is the vacuum dielectric constant, A is the area of the capacitor, and d is the film thickness. As a result, the relative dielectric constants of Layer 1 and Layer 2 were 32.7 and 2.81, respectively.

Since the dielectric layer of the comparative example 2 has a higher dielectric constant than the layer 1 which is the dielectric layer of the comparative example 1, the comparative example 2 is expected to have a larger current value. However, in Table 1, the current value of Comparative Example 2 is lower than that of Comparative Example 1. This is because the contact area with the charging member that is negatively charged during frictional power generation is reduced due to the size of the surface unevenness of the layer 2 and the low flexibility, and the barium titanate contained in the layer 2 is reduced. It can be considered that the charged charge tends to disappear because it has higher hygroscopicity than PMMA.
On the other hand, in Example 1 which has the layer 2 in the outermost layer, it turned out that the electric current value higher than any of the comparative examples 1 and 2 is obtained.

1, 2, 3 Friction generator
10, 20, 30 Electrical load 110, 210, 310 First charging member 111, 211, 311 First electrode 112, 212, 312 Dielectric layer 113, 213, 313, 323 Outermost layer 120, 220, 320 Second charging Member 121,221,321 Second electrode 122,322 Dielectric layer

Claims (6)

A friction generator including charging members provided to face each other,
At least one of the charging members has an electrode, a dielectric layer, and an outermost layer,
The dielectric generator has a matrix and particles, and the relative dielectric constant of the particles is higher than the relative dielectric constant of the matrix. The frictional generator according to claim 1, wherein the dielectric layer has a relative dielectric constant (ε _DI ) of 5 or more. It said dielectric layer thickness of d _DI of the the outermost layer of the film thickness and d _Sf, a d _Sf / d _DI <1, friction generator according to claim 1 or 2. The frictional generator according to any one of claims 1 to 3, wherein d _DI is 10 µm or more and 500 µm or less. The frictional generator according to any one of claims 1 to 4, wherein d _Sf is 1 µm or more and 100 µm or less. The friction generator according to any one of claims 1 to 5, wherein the dielectric layer and the outermost layer contain the same polymer.

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