JP5916270B2 - Dielectric film and transducer using the same - Google Patents

Description

  The present invention relates to a dielectric film suitable for a transducer such as an actuator or a sensor, and a transducer using the dielectric film.

  Examples of the transducer include an actuator that converts mechanical energy and electric energy, a sensor, a power generation element, and the like, or a speaker that converts acoustic energy and electric energy, a microphone, and the like. Polymer materials such as dielectric elastomers are useful for constructing a highly flexible, small and lightweight transducer.

  For example, an actuator can be configured by arranging a pair of electrodes on both sides in the thickness direction of a dielectric film made of a dielectric elastomer. In this type of actuator, increasing the voltage applied between the electrodes increases the electrostatic attractive force between the electrodes. For this reason, the dielectric film sandwiched between the electrodes is compressed in the thickness direction, and the thickness of the dielectric film is reduced. As the film thickness decreases, the dielectric film extends in a direction parallel to the electrode surface. On the other hand, when the applied voltage between the electrodes is reduced, the electrostatic attractive force between the electrodes is reduced. For this reason, the compressive force from the thickness direction to the dielectric film is reduced, and the film thickness is increased by the elastic restoring force of the dielectric film. As the film thickness increases, the dielectric film shrinks in the direction parallel to the electrode surface. Thus, the actuator drives the member to be driven by extending and contracting the dielectric film.

  As the dielectric film of the actuator, acrylic rubber, silicone rubber, fluorine rubber, nitrile rubber or the like is used. Further, it is desirable that the actuator has a larger displacement amount (expansion / contraction amount) of the dielectric film with respect to the applied voltage. For example, the higher the relative dielectric constant of the dielectric film, the more charge can be stored at the interface between the dielectric film and the electrode. Thereby, the displacement amount of the dielectric film, that is, the actuator can be increased. From such a viewpoint, attempts have been made to blend fine particles having a high dielectric constant such as barium titanate into the elastomer (for example, see Patent Documents 1 and 2).

Special table 2003-505865 gazette JP 2008-53527 A

  In an actuator using a conventional dielectric film made of acrylic rubber or the like, the amount of displacement is not sufficient. That is, when a material having a low relative dielectric constant such as silicone rubber is used, the electrostatic attractive force with respect to the applied voltage is small. Therefore, the responsiveness at the time of voltage application is bad. That is, the amount of displacement is small. On the other hand, the relative dielectric constant of nitrile rubber is relatively high. For this reason, when nitrile rubber is used, the electrostatic attraction with respect to the applied voltage becomes larger than when silicone rubber or the like is used. However, even when a dielectric film made of nitrile rubber is used, the amount of displacement is not yet satisfactory. Moreover, a dielectric film made of nitrile rubber is poor in flexibility. Therefore, even if a large electrostatic attraction occurs when a voltage is applied, the dielectric film is difficult to expand. That is, if the dielectric film has low flexibility, the generated electrostatic attractive force is difficult to be replaced by displacement. As described above, the relative permittivity and low flexibility of the dielectric film contribute to the inability to obtain a sufficient amount of displacement in the actuator.

  Furthermore, when the high dielectric constant fine particles are blended in the elastomer, it is difficult to maintain the flexibility of the dielectric film. That is, by blending fine particles having a high dielectric constant, the dielectric constant of the dielectric film is improved, but the elastic modulus of the elastomer is increased and the elongation is reduced. That is, the inherent flexibility of the elastomer is impaired. As a result, expansion and contraction of the dielectric film with respect to the applied voltage may be hindered.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a flexible dielectric film having a high relative dielectric constant. It is another object of the present invention to provide a transducer having a large displacement amount using the dielectric film.

  (1) In order to solve the above problems, the dielectric film of the present invention includes an elastomer having a hetero atom in the molecule, and a high dielectric constant liquid compound having a hetero atom in the molecule and compatible with the elastomer. The elastomer composition is crosslinked (corresponding to claim 1).

  A “heteroatom” is an atom other than a carbon atom (C) and a hydrogen atom (H). Both the elastomer and the high dielectric constant liquid compound constituting the dielectric film of the present invention contain heteroatoms in the molecule. By including a heteroatom, polarization is likely to occur as compared with the case of only C and H. For this reason, the relative dielectric constants of the elastomer and the liquid compound having a high dielectric constant are higher than those having no hetero atom. The dielectric film of the present invention is formed by crosslinking an elastomer composition containing these. Therefore, the dielectric constant of the dielectric film of the present invention is high.

  A high dielectric constant liquid compound is a compound having a high relative dielectric constant and exhibiting a liquid state at room temperature. The compatibility between the high dielectric constant liquid compound and the elastomer is good. For this reason, unlike fine particles having a high dielectric constant, there is no possibility of reducing the flexibility of the dielectric film even when mixed with an elastomer. Thus, the dielectric film of the present invention has both a high relative dielectric constant and flexibility. Therefore, the dielectric film of the present invention has a large expansion / contraction amount with respect to the applied voltage.

  (2) Moreover, the transducer of the present invention crosslinks an elastomer composition containing an elastomer having a hetero atom in the molecule and a high dielectric constant liquid compound having a hetero atom in the molecule and compatible with the elastomer. And a plurality of electrodes arranged via the dielectric film (corresponding to claim 8).

  The transducer of the present invention includes the dielectric film of the present invention. The dielectric film is as described in (1) above. That is, in the transducer of the present invention, the dielectric film has a high relative dielectric constant. Therefore, a large amount of charge can be stored at the interface between the dielectric film and the electrode. In addition, the dielectric film is flexible. For this reason, for example, when the transducer of the present invention is used as an actuator, a large amount of displacement can be obtained at a lower voltage.

  According to the present invention, a flexible dielectric film having a high relative dielectric constant can be provided. In addition, a transducer with a large displacement can be provided using the dielectric film.

It is a cross-sectional schematic diagram of the actuator which is one Embodiment of the transducer of this invention, Comprising: (a) shows an OFF state, (b) shows an ON state, respectively. It is a cross-sectional schematic diagram of the capacitive sensor which is one Embodiment of the transducer of this invention. It is a cross-sectional schematic diagram of the electric power generating element which is one Embodiment of the transducer of this invention, Comprising: (a) is at the time of expansion | extension, (b) shows the time of contraction. It is a top view of the actuator used for the evaluation experiment of an Example. It is VV sectional drawing in FIG.

  Hereinafter, embodiments of the dielectric film and the transducer of the present invention will be described. The dielectric film and the transducer of the present invention are not limited to the following embodiments, and can be variously modified and improved by those skilled in the art without departing from the gist of the present invention. Can be implemented.

<Dielectric film>
The dielectric film of the present invention is formed by crosslinking an elastomer composition containing an elastomer having a hetero atom in the molecule and a high dielectric constant liquid compound having a hetero atom in the molecule and compatible with the elastomer.

  The hetero atom contained in each molecule of the elastomer and the high dielectric constant liquid compound may be one kind or two or more kinds. Further, the types of heteroatoms may be the same or different in each of the elastomer and the high dielectric constant liquid compound.

  It is desirable that the hetero atom contains an atom having a large electronegativity from the viewpoint of increasing the relative dielectric constant of the elastomer and the high dielectric constant liquid compound. An atom with a high electronegativity has a large electron withdrawing force (a force to attract a shared electron pair). For this reason, a molecule containing an atom having a large electronegativity is easily polarized. That is, the relative dielectric constant of the molecule increases. Examples of atoms having a large electronegativity include halogen atoms such as fluorine (F) and chlorine (Cl), nitrogen (N), oxygen (O), and the like.

  As the elastomer having a hetero atom in the molecule, one having a relatively large electric resistance is desirable. Of these, those having a relatively high relative dielectric constant and those having flexibility are preferred. For example, acrylic rubber, silicone rubber, acrylonitrile-butadiene copolymer (NBR), hydrogenated nitrile rubber (H-NBR), hydrin rubber, chloroprene rubber, chlorinated polyethylene, chlorosulfonated polyethylene rubber, fluorine rubber, urethane rubber One or more selected may be used.

  The high dielectric constant liquid compound having a hetero atom in the molecule may be selected in consideration of compatibility with the elastomer. The compatibility can be determined using, for example, an SP value (solubility parameter) as an index. That is, when the SP values of the high dielectric constant liquid compound and the elastomer are close, the compatibility between the two is considered good.

  The relative dielectric constant of the high dielectric constant liquid compound is desirably 20 or more. Moreover, the thing with a comparatively large electrical resistance is desirable. In addition, even if the electrical resistance of the high dielectric constant liquid compound is not so large, it is sufficient if it can maintain high insulation when mixed with an elastomer to form a dielectric film.

  Examples of such a high dielectric constant liquid compound include chlorinated paraffin, adipic acid ester, and sulfonamide. One of these may be used alone or in combination of two or more. For example, a compound having a structure in which the main chain is composed of hydrocarbons and has a chlorine atom (heteroatom) in the side chain, such as chlorinated paraffin, has a high insulation property derived from the main chain and a dielectric constant derived from the side chain. It is suitable because it has both high rate.

  What is necessary is just to adjust the compounding quantity of a high dielectric constant liquid compound suitably according to compatibility with an elastomer. From the viewpoint of improving the relative dielectric constant and flexibility of the dielectric film, the blending amount of the high dielectric constant liquid compound is desirably 5 parts by mass or more with respect to 100 parts by mass of the elastomer, for example. More preferably, it is 15 parts by mass or more. On the other hand, depending on the compatibility with the elastomer, if a high dielectric constant liquid compound is blended in a large amount, wrinkles or the like may occur during film formation, and a uniform film may not be formed. Therefore, the blending amount of the high dielectric constant liquid compound is desirably less than 400 parts by mass with respect to 100 parts by mass of the elastomer, for example. More preferably, it is 300 parts by mass or less.

  An elastomer composition is prepared by mixing an elastomer and a high dielectric constant liquid compound. A cross-linking agent, a vulcanization accelerator, a processing aid, a plasticizer, an anti-aging agent, a reinforcing agent, a colorant, and the like may be added to the elastomer composition as necessary. For example, when a crosslinking agent is added, it may be appropriately selected from sulfur, an isocyanate compound, a peroxide and the like according to the type of elastomer. In addition, when a metal alkoxide compound is used as the cross-linking agent, it is possible to suppress a decrease in insulating properties of the dielectric film. That is, when a metal alkoxide compound is used, in the crosslinked body (dielectric film), the flow of electrons is blocked by the inorganic substance (metal oxide), so that it is considered that the insulating property is increased.

A metal alkoxide compound is represented by the following general formula (a), for example.
M (OR) _m ... (a)
[In formula (a), M is an atom such as a metal. R is 1 or more types of a C1-C10 alkyl group, an aryl group, and an alkenyl group, and may be same or different. m is the valence of an atom M such as a metal. ]
In addition, a multimer having two or more repeating units [(MO) _n ; n is an integer of 2 or more] in one molecule may be used. By changing the number of n, compatibility with the elastomer, reaction rate, and the like can be adjusted. For this reason, a suitable multimer is suitably selected according to the kind of elastomer.

  Examples of the atom M such as metal include titanium, zirconium, aluminum, silicon, iron, copper, tin, barium, strontium, hafnium, boron, and the like. Among them, those containing at least one selected from titanium, zirconium, and aluminum are desirable because of good reactivity. Specifically, tetra n-butoxy titanium, tetra n-butoxy zirconium, tetra n-butoxy silane, acetoalkoxy aluminum diisopropylate, tetra i-propoxy titanium, tetraethoxy silane and the like are preferable.

  The elastomer composition can be prepared, for example, by kneading an elastomer, a high dielectric constant liquid compound, and, if necessary, an additive with a roll or a kneader. Further, when a metal alkoxide compound is used as a crosslinking agent, the metal alkoxide compound is mixed with the mixed solution of the elastomer and the high dielectric constant liquid compound as it is or dissolved in a predetermined solvent. be able to.

  The metal alkoxide compound reacts with moisture in the air or reaction system, and is hydrolyzed and polycondensed (sol-gel reaction). Therefore, in order to suppress a rapid reaction with water and form a homogeneous film, it is desirable to use a metal alkoxide compound after chelating with a chelating agent. By chelating, hydrolysis of the metal alkoxide compound is suppressed. Therefore, the chelating agent may be removed later to accelerate the hydrolysis of the metal alkoxide compound and advance the crosslinking reaction by polycondensation.

  Examples of chelating agents include β-diketones such as acetylacetone, benzoylacetone, and dibenzoylmethane, β-ketoacid esters such as ethyl acetoacetate and ethyl benzoylacetate, triethanolamine, lactic acid, 2-ethylhexane-1,3 Examples include diol and 1,3 hexanediol.

  The dielectric film of the present invention can be produced by filling the prepared elastomer composition into, for example, a mold and press-crosslinking under predetermined conditions. When a metal alkoxide compound is used, first, the prepared elastomer composition is applied to a substrate or the like. Next, it can manufacture by drying a coating film, evaporating a solvent (chelating agent), and making a crosslinking reaction advance.

<Transducer>
The transducer of the present invention includes a dielectric film and a plurality of electrodes arranged via the dielectric film. Here, the dielectric film is formed by crosslinking an elastomer composition containing an elastomer having a hetero atom in the molecule and a high dielectric constant liquid compound having a hetero atom in the molecule and compatible with the elastomer.

  The configuration of the dielectric film such as an elastomer and a high dielectric constant liquid compound, and the manufacturing method are as described in the embodiment of the dielectric film of the present invention. Therefore, the description is omitted here. In the transducer according to the present invention, it is desirable to adopt a preferable aspect of the dielectric film according to the present invention.

  What is necessary is just to determine the thickness of a dielectric film suitably according to a use etc. For example, when the transducer of the present invention is used as an actuator, it is desirable that the thickness of the dielectric film is small from the viewpoints of downsizing the actuator, driving at a low potential, and increasing the amount of displacement. In this case, it is desirable that the thickness of the dielectric film be 1 μm or more and 1000 μm (1 mm) or less in consideration of dielectric breakdown properties and the like. A more preferable range is 5 μm or more and 200 μm or less.

  In the transducer of the present invention, the material of the electrode is not particularly limited. For example, a conductive material made of carbon material such as carbon black or carbon nanotube or a conductive material made of metal and a paste or paint mixed with oil or elastomer as a binder, or an electrode made by knitting carbon material or metal in a mesh shape, etc. Can be used. It is desirable that the electrode can expand and contract according to the expansion and contraction of the dielectric film. When the electrode expands and contracts together with the dielectric film, the deformation of the dielectric film is not easily disturbed by the electrode. For this reason, when the transducer of the present invention is used as an actuator or the like, a desired amount of displacement can be easily obtained.

  Further, when the transducer of the present invention has a laminated structure in which a plurality of dielectric films and electrodes are alternately laminated, a larger force can be generated. Therefore, when the laminated structure is adopted, for example, the output of the actuator can be increased. As a result, the member to be driven can be driven with a greater force.

[First embodiment]
As a first example of the transducer of the present invention, an embodiment embodied in an actuator will be described. FIG. 1 is a schematic cross-sectional view of the actuator of this embodiment. (A) shows an OFF state, and (b) shows an ON state.

  As shown in FIG. 1, the actuator 1 includes a dielectric film 10 and electrodes 11a and 11b. The dielectric film 10 is a cross-linked product (dielectric film of the present invention) of an elastomer composition containing an elastomer and a high dielectric constant liquid compound. The electrodes 11a and 11b are fixed to the upper and lower surfaces of the dielectric film 10, respectively. The electrodes 11a and 11b are connected to the power source 12 via a conducting wire. When switching from the off state to the on state, a voltage is applied between the pair of electrodes 11a and 11b. Due to the application of voltage, the thickness of the dielectric film 10 is reduced, and accordingly, the dielectric film 10 extends in the direction parallel to the surfaces of the electrodes 11a and 11b, as indicated by white arrows in FIG. Thereby, the actuator 1 outputs the driving force in the vertical direction and the horizontal direction in the drawing.

  The dielectric film 10 has both a high relative dielectric constant and flexibility. Therefore, the dielectric film 10 has a large amount of expansion and contraction with respect to the applied voltage. That is, according to the actuator 1, a large displacement can be obtained at a lower voltage. Further, when the dielectric film 10 is attached in a state extending in the surface extending direction, the dielectric breakdown strength of the dielectric film 10 is improved, and a larger amount of displacement can be obtained.

[Second Embodiment]
As a second example of the transducer of the present invention, an embodiment embodied in a capacitive sensor will be described. FIG. 2 is a schematic cross-sectional view of the capacitive sensor according to this embodiment. As shown in FIG. 2, the capacitive sensor 2 includes a dielectric film 20, electrodes 21 a and 21 b, and a substrate 22. The dielectric film 20 is a crosslinked body (dielectric film of the present invention) of an elastomer composition containing an elastomer and a high dielectric constant liquid compound. The dielectric film 20 has a strip shape extending in the left-right direction. The dielectric film 20 is disposed on the upper surface of the substrate 22 via the electrode 21b. The electrodes 21a and 21b have a strip shape extending in the left-right direction. The electrodes 21a and 21b are fixed to the upper and lower surfaces of the dielectric film 20, respectively. Conductive wires (not shown) are connected to the electrodes 21a and 21b. The substrate 22 is an insulating flexible film and has a strip shape extending in the left-right direction. The substrate 22 is fixed to the lower surface of the electrode 21b.

The capacitance (capacitance) of the capacitance type sensor 2 can be obtained by the following equation (I).
C = ε ₀ ε _r S / d (I)
[C: capacitance, ε ₀ : dielectric constant in vacuum, ε _r : relative dielectric constant of dielectric film, S: electrode area, d: distance between electrodes]
For example, when the capacitive sensor 2 is pressed from above, the dielectric film 20 is compressed and correspondingly extends in the direction parallel to the surfaces of the electrodes 21a and 21b. As the film thickness, that is, the inter-electrode distance d decreases, the capacitance between the electrodes 21a and 21b increases. The magnitude, position, etc. of the applied load are detected by this capacitance change.

  Here, the dielectric film 20 has both a high relative dielectric constant and flexibility. Since the relative dielectric constant of the dielectric film 20 is high, the capacitance is large. Further, since the dielectric film 20 is flexible, it is easily deformed with respect to an external load. That is, the displacement amount of the interelectrode distance d is large. Therefore, the detection sensitivity of the capacitive sensor 2 is high. In addition, the dielectric film 20 is unlikely to deteriorate even after repeated expansion and contraction. Therefore, the capacitance type sensor 2 is excellent in durability.

[Third embodiment]
An embodiment of a power generation element will be described as a third example of the transducer of the present invention. In FIG. 3, the cross-sectional schematic diagram of the electric power generation element in this embodiment is shown. (A) shows the time of expansion, and (b) shows the time of contraction. As shown in FIG. 3, the power generation element 3 includes a dielectric film 30 and electrodes 31a and 31b. The dielectric film 30 is a crosslinked body (dielectric film of the present invention) of an elastomer composition containing an elastomer and a high dielectric constant liquid compound. The electrodes 31a and 31b are fixed to the upper and lower surfaces of the dielectric film 30, respectively. Conductive wires are connected to the electrodes 31a and 31b, and the electrode 31b is grounded.

  As shown in FIG. 3A, when the power generating element 3 is compressed and the dielectric film 30 is extended in a direction parallel to the surfaces of the electrodes 31a and 31b, the thickness of the dielectric film 30 is reduced, and between the electrodes 31a and 31b. The charge is stored in Thereafter, when the compressive force is removed, the dielectric film 30 contracts due to the elastic restoring force of the dielectric film 30 and the film thickness increases as shown in FIG. At that time, electric charges are released and electric power is generated.

  Here, the dielectric film 30 has both a high relative dielectric constant and flexibility. Since the dielectric constant of the dielectric film 30 is high, a large amount of charges can be stored at the interface with the electrodes 31a and 31b. Further, since the dielectric film 30 is flexible, it is easily deformed with respect to an external load. That is, the expansion amount by compression is large. Therefore, the power generation amount of the power generation element 3 is large. In addition, the dielectric film 30 is unlikely to deteriorate even if the expansion and contraction is repeated. Therefore, the power generating element 3 is excellent in durability.

  Next, the present invention will be described more specifically with reference to examples.

<Manufacture of dielectric film>
[Dielectric film of Examples 1-3]
Dielectric films of Examples 1 to 3 were manufactured from the raw materials shown in Table 1 below. First, a predetermined raw material was kneaded with a roll kneader to prepare an elastomer composition. Next, the prepared elastomer composition was molded into a thin sheet, filled in a mold, and press-crosslinked at 150 ° C. for about 30 minutes. The obtained crosslinked product was further crosslinked in an oven at 150 ° C. for about 4 hours.

[Dielectric film of Comparative Examples 1 to 5]
Dielectric films of Comparative Examples 1 to 5 were manufactured from the raw materials shown in Table 1 below in the same manner as the dielectric films of Examples 1 to 3. The main difference between the dielectric films of Examples 1 to 3 and the dielectric films of Comparative Examples 1 to 5 is the presence or absence of a high dielectric constant liquid compound. Example 1 and Comparative Example 1, Example 2 and Comparative Examples 2 to 4, Example 3 and Comparative Example 5 correspond to each other in that the elastomers are the same. In Comparative Examples 3 and 4, bleeding occurred during film formation, and a homogeneous dielectric film could not be obtained. This is probably because the compatibility between the elastomer and the hydrocarbon oil is poor.

In Table 1, the following were used for each raw material.
(1) Elastomer hydrogenated nitrile rubber (a): “Zetpol (registered trademark) 0020” manufactured by Zeon Corporation
Hydrogenated nitrile rubber (b): “Zetpol 1010” manufactured by Nippon Zeon Co., Ltd.
Hydrogenated nitrile rubber (c): “Zetpol 1000L” manufactured by Nippon Zeon Co., Ltd.
(2) High dielectric constant liquid compound adipic acid ester: [ROCO (CH ₂ ) ₄ COOR], “ADEKA SIZER (registered trademark) RS107” manufactured by ADEKA Corporation
(3) Hydrocarbon oil (additive)
Naphthenic oil: “Diana (registered trademark) process oil NM-280” manufactured by Idemitsu Kosan Co., Ltd.
Paraffin oil: “Diana Process Oil PW-380” manufactured by Idemitsu Kosan Co., Ltd.
(4) Dipentamethylene thiuram tetrasulfide such as a cross-linking agent: “Sunseller (registered trademark) TRA” manufactured by Sanshin Chemical Industry Co., Ltd.
N-cyclohexyl-2-benzothiazylsulfenamide: “Sunceller CZ-G” manufactured by Sanshin Chemical Industry Co., Ltd.
Sulfur: "Sulfax T-10" manufactured by Tsurumi Chemical Co., Ltd.
Dicumyl peroxide: “Park Mill (registered trademark) D” manufactured by NOF Corporation

[Dielectric films of Examples 4 to 7]
Dielectric films of Examples 4 to 7 were manufactured from the raw materials shown in Table 2 below. First, an elastomer, a high dielectric constant liquid compound, and acetylacetone were mixed. Tetra i-propoxy titanium (metal alkoxide compound) was added to this solution and mixed. Acetylacetone is a chelating agent for metal alkoxide compounds. Next, the mixed solution was applied onto the substrate, dried, and then crosslinked at 150 ° C. for about 1 hour.

[Dielectric films of Comparative Examples 6 and 7]
Dielectric films of Comparative Examples 6 and 7 were manufactured from the raw materials shown in Table 2 below in substantially the same manner as the dielectric films of Examples 4 to 7. The dielectric film of Comparative Example 6 is different from the dielectric films of Examples 4 to 7 in that no high dielectric constant liquid compound is blended. Moreover, about the dielectric film of the comparative example 7, the compounding quantity of the high dielectric constant liquid compound (chlorinated paraffin) was increased compared with the dielectric film of Examples 5-7. In Comparative Example 7, a film could not be formed because wrinkles occurred in the coating film on the substrate. This is probably because the amount of the high dielectric constant liquid compound was too large for the elastomer.

In Table 2, the following were used for each raw material.
(1) Elastomer COOH group-containing hydrogenated nitrile rubber: “Telvan (registered trademark) XT8889” manufactured by LANXESS
(2) High dielectric constant liquid compound chlorinated paraffin: [C ₂₆ H _46.9 Cl _7.1 ], “Empara (registered trademark) 40” manufactured by Ajinomoto Fine Techno Co., Ltd.
Sulfonamide: [C ₆ H ₅ SO ₂ —NHC ₄ H ₉ ], “BM-4” manufactured by Daihachi Chemical Industry Co., Ltd.
(3) Tetra i-propoxy titanium, such as a crosslinking agent: manufactured by Nippon Soda Co., Ltd.

<Physical properties of dielectric film>
[100% modulus, tensile strength, and elongation at break]
The dielectric films of Examples and Comparative Examples were measured for 100% modulus (tensile stress: M ₁₀₀ ), tensile strength (TS), and elongation at break (E _b ). These measurements were performed according to JIS K 6251 (2004). In addition, the test piece used dumbbell-shaped No. 2. The measurement results are summarized in Tables 1 and 2 above.

  In Table 1, when the same type of elastomer is compared, Example 1 is 100% modulus with respect to Comparative Example 1, Example 2 is with respect to Comparative Example 2, and Example 3 is with respect to Comparative Example 5. Became smaller. Similarly, in Table 2, Examples 4 to 7 had a 100% modulus smaller than that of Comparative Example 6. Further, as can be seen from the results of the dielectric films of Examples 5 to 7 in Table 2, when the same kind of high dielectric constant liquid compound was blended, the 100% modulus decreased as the blending amount increased. From these results, it can be seen that the dielectric film of the example blended with the high dielectric constant liquid compound is more flexible than the dielectric film of the comparative example not blended with the compound.

  In Table 1, the elongation at break was larger in Example 1 than in Comparative Example 1, in Example 2 in Comparative Example 2, and in Example 3 with respect to Comparative Example 5. Similarly, in Table 2, Examples 4 to 6 were larger in elongation at break than Comparative Example 6. Although the elongation at break in Example 7 was slightly smaller than that in Comparative Example 6, it was a practically sufficient value. As described above, in the dielectric film of the example, since the high dielectric constant liquid compound is blended, the 100% modulus is reduced. If the compatibility between the high dielectric constant liquid compound and the elastomer is poor, a sea-island phase is formed in the dielectric film. In this case, in the tensile test, the liquid island phase is the starting point and is cut early. In this respect, according to the dielectric film of the embodiment, a desired elongation at the time of cutting is ensured. This confirms that the compatibility between the high dielectric constant liquid compound and the elastomer is good.

[Electric resistance]
The electric resistances of the dielectric films of Examples and Comparative Examples were measured according to JIS K 6911 (1995). The measurement results are summarized in Tables 1 and 2 above. As shown in Tables 1 and 2, the dielectric films of the examples all have a large electric resistance. That is, high insulation is maintained. Specifically, in Table 1, when comparing the same types of elastomers, Example 1 is for Comparative Example 1, Example 2 is for Comparative Example 2, and Example 3 is for Comparative Example 5. The electrical resistance was slightly reduced. On the other hand, when Examples 4 to 7 and Comparative Example 6 were compared in Table 2, the electrical resistance was comparable.

[Relative permittivity]
The relative dielectric constants of the dielectric films of Examples and Comparative Examples were measured. For measurement of relative dielectric constant, each dielectric film is placed in a sample holder (Solartron, type 12962A), and a dielectric constant measurement interface (manufactured by the company, type 1296) and a frequency response analyzer (made by the company, type 1255B) are used in combination. And measured (frequency 100 Hz). The measurement results are summarized in Tables 1 and 2 above. In Table 1, when comparing the same kind of elastomers, Example 1 is relative to Comparative Example 1, Example 2 is relative to Comparative Example 2, and Example 3 is relative to Comparative Example 5. Became high. Similarly, in Table 2, Examples 4 to 7 had higher dielectric constants than Comparative Example 6. In Table 2, as can be seen from the results of the dielectric films of Examples 5 to 7, when the same kind of high dielectric constant liquid compound was blended, the relative dielectric constant increased as the blending amount increased.

<Actuator evaluation>
Next, an actuator was configured using each dielectric film of the example and the comparative example, and the displacement amount of the actuator was evaluated. First, an experimental apparatus and an experimental method will be described.

  Actuators were constructed by attaching electrodes made of a mixture of acrylic rubber and carbon black to the upper and lower surfaces of each dielectric film of the examples and comparative examples. Hereinafter, the manufactured actuator is referred to as an actuator of an example or a comparative example corresponding to the type of dielectric film. FIG. 4 shows a top view of the manufactured actuator. FIG. 5 shows a VV cross-sectional view in FIG.

As shown in FIGS. 4 and 5, the actuator 5 includes a dielectric film 50 and a pair of electrodes 51 a and 51 b. The dielectric film 50 has a circular thin film shape with a diameter of 70 mm. The dielectric film 50 is arranged in a state of being stretched in advance in the biaxial direction at a predetermined stretching rate. Here, the stretching ratio is a value calculated by the following formula (II) (hereinafter referred to as “preliminary stretching ratio”).
Stretch rate (%) = {√ (S ₂ / S ₁ ) −1} × 100 (II)
[S ₁ : Dielectric film area before stretching (natural state), S ₂ : Dielectric film area after biaxial stretching]
The pair of electrodes 51a and 51b are arranged to face each other in the vertical direction with the dielectric film 50 interposed therebetween. The electrodes 51a and 51b have a circular thin film shape with a diameter of about 27 mm, and are arranged substantially concentrically with the dielectric film 50, respectively. A terminal portion 510a protruding in the diameter increasing direction is formed on the outer peripheral edge of the electrode 51a. The terminal portion 510a has a rectangular plate shape. Similarly, a terminal portion 510b protruding in the diameter increasing direction is formed on the outer peripheral edge of the electrode 51b. The terminal portion 510b has a rectangular plate shape. The terminal portion 510b is disposed at a position facing the terminal portion 510a by 180 °. Terminal portions 510a and 510b are each connected to power supply 52 via a conducting wire.

  When a voltage is applied between the electrodes 51a and 51b, an electrostatic attractive force is generated between the electrodes 51a and 51b, and the dielectric film 50 is compressed. Thereby, the thickness of the dielectric film 50 becomes thin and extends in the diameter expansion direction. At this time, the electrodes 51a and 51b are also integrated with the dielectric film 50 and extend in the diameter increasing direction. A marker 530 is attached to the electrode 51a in advance. The displacement of the marker 530 was measured by the displacement meter 53 and used as the displacement amount of the actuator 5. The applied voltage was an electric field strength of 50 V / μm and a frequency of 1 Hz.

Next, the measurement results of the displacement amount for the actuators of the example and the comparative example are collectively shown in Tables 1 and 2 above. The maximum displacement rates shown in Tables 1 and 2 are values calculated by the following formula (III).
Maximum displacement rate (%) = (maximum displacement amount / radius of electrode) × 100 (III)
In addition, the thickness of the dielectric film and the prestretch ratio in each actuator are also shown in Tables 1 and 2.

  As shown in Tables 1 and 2 above, according to the actuators of the examples, the maximum displacement rate was increased. Specifically, in Table 1, when comparing the same types of elastomers, Example 1 is for Comparative Example 1, Example 2 is for Comparative Example 2, and Example 3 is for Comparative Example 5. The maximum displacement rate has increased. Similarly, in Table 2, Examples 4 to 7 had a larger maximum displacement rate than Comparative Example 6. From the above, it was confirmed that according to the dielectric film of the present invention, an actuator with a large displacement can be configured. In this example, the dielectric film was placed in a pre-stretched state, and the amount of displacement in the diameter expansion direction was measured. However, even in an experiment in which the dielectric film was arranged without being pre-stretched and displaced in the thickness direction, it was confirmed that the amount of displacement increased.

  The dielectric film of the present invention has a high relative dielectric constant and flexibility. For this reason, it can be widely used for transducers that convert mechanical energy and electrical energy, or convert acoustic energy and electrical energy. For example, the transducer comprising the dielectric film of the present invention is an artificial muscle for industrial, medical, and welfare robots, a small pump for cooling electronic components, medical devices, etc., and a flexible actuator used for medical instruments. It can be used as a flexible sensor such as a capacitive sensor, and a power generation element.

1: Actuator (transducer) 10: Dielectric film 11a, 11b: Electrode 12: Power supply 2: Capacitance type sensor (transducer) 20: Dielectric film 21a, 21b: Electrode 22: Substrate 3: Power generation element (transducer) 30: Dielectric Film 31a, 31b: Electrode 5: Actuator 50: Dielectric film 51a, 51b: Electrode 52: Power supply 53: Displacement meter 510a, 510b: Terminal part 530: Marker

Claims (1)

And one or more e elastomer selected from hydrogenated nitrile rubber and COOH group-containing hydrogenated nitrile rubber, adipic acid esters, chlorinated paraffin, and one or more liquid compounds selected from sulfonamide, an elastomer composition comprising a crosslinked A dielectric film,
The amount of the liquid compound in the elastomer composition is less 300 weight parts 5 parts by mass or more with respect to 100 parts by weight of the elastomer,
A dielectric film having a 100% modulus of 0.9 MPa or less;
A plurality of electrodes disposed through the dielectric film and including an elastomer and a conductive material;
A transducer comprising:

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