JP2021038290A - Dielectric elastomer, and actuator using the same - Google Patents

Abstract

To provide a dielectric elastomer including urethane-based elastomer which is suitable for an actuator, whose withstand voltage is improved stably with time, and more preferably space charge is suppressed stably with time.SOLUTION: A dielectric elastomer includes urethane-based elastomer and BaSO4 which is blended as a filler and has an average primary particle diameter of 1000 nm or less. It is preferable that the average primary particle diameter be 500 nm or less, and it is preferable that a blended amount of BaSO4 with respect to the entire dielectric elastomer be 0.1 to 50 mass%.SELECTED DRAWING: Figure 5

Description

The present invention relates to a dielectric elastomer and an actuator using the same.

The dielectric elastomer actuator is a drive device having a basic structure in which a dielectric elastomer molded product is sandwiched between two electrodes. When a voltage is applied between the two electrodes, the Coulomb force generated between the electrodes causes the dielectric elastomer molded body to contract and deform in the direction between the electrodes, and then expand and deform in the direction perpendicular to the electrode. It becomes a drive device to take out as.

Patent Document 1 describes a grip in which crosslinked polyrotaxane is used as a dielectric layer to form bendable and deformable electrodes on both sides thereof, a power supply unit for applying a voltage between the electrodes, and a state in which the grip is bent and before the grip is bent. An article gripping device having a switching unit for switching between states is disclosed.

Japanese Unexamined Patent Publication No. 2019-41459 Japanese Patent No. 5261145

However, among the dielectric elastomers, urethane-based elastomers in particular are required to have a further improvement in withstand voltage.

In addition, urethane-based elastomers also have a problem of space charge. That is, when a voltage is applied to the urethane-based elastomer, an excessive absorption current flows in the initial stage after the start of application to generate heat, and the dielectric breakdown voltage may decrease. Further, when a DC voltage of a square wave is applied, the amplitude of displacement may become unstable at the initial stage after the start of application, which is a problem for actuators that require accurate operation. The reason for these is that when a voltage is applied, space charges that are biased to either positive or negative are accumulated inside the dielectric elastomer molded body, and as a result, there are places where the electric field is locally concentrated inside. It is presumed that this was due to the occurrence.

Patent Document 1 described above describes the principle of bending the grip so that the stress distribution becomes non-uniform due to the space charge generated inside the dielectric layer, and the positive electrode side of the dielectric layer bends inward in the bending direction. .. That is, Patent Document 1 utilizes space charge, and does not mention suppressing space charge at all.

Expanding to technical fields other than the dielectric elastomer actuator, Patent Document 2 states that in the cross-linked polyethylene composition used for the insulator of a DC power cable, the decomposition residue of dicumyl peroxide, which is a cross-linking agent, has a space charge. When a predetermined carbon black or a predetermined magnesium oxide is added as the inorganic filler, the decomposition residue is adsorbed on the surface of the inorganic filler, thereby suppressing the space charge. It is disclosed that the action to be performed is expected.

However, it is unclear whether the carbon black or magnesium oxide exerts a similar space charge suppressing effect on urethane-based elastomers.

Therefore, an object of the present invention is to provide a dielectric elastomer containing a urethane-based elastomer, which is suitable for an actuator, is stable over time and has an improved withstand voltage, and more preferably is stable over time and suppresses space charge. To do.

_{(1) Dielectric Elastomer A dielectric elastomer containing a urethane-based elastomer and BaSO 4} having an average primary particle size of 1000 nm or less, which is blended as a filler.
The average primary particle size is given by the average primary particle size = ΣNi · Di / ΣNi, where Ni is the number of particles in each particle size section and the center value of the particle size section is Di.

Here, the urethane-based elastomer is preferably a crosslinked polyrotaxane. This is because the crosslinked polyrotaxane has a high dielectric constant suitable for a dielectric actuator.

The initial elastic modulus of the dielectric elastomer is preferably 0.1 to 10 MPa, more preferably 0.5 to 3 MPa. This is because such a low elastic modulus is suitable for a dielectric actuator.

The average primary particle size is preferably 500 nm or less, more preferably 5 to 300 nm, and most preferably 5 to 100 nm. _{Further, the blending amount of BaSO 4} with respect to the entire dielectric elastomer is preferably 0.1 to 50% by mass, more preferably 2 to 20% by mass. These reasons will be explained in <Action> below.

The volume resistivity of the dielectric elastomer is preferably 2.0E + 11Ω · cm or more. This is because high resistance is suitable for dielectric actuators.

<Action>
_{When BaSO 4} having an average primary particle size of 1000 nm or less is blended as a filler, the dielectric breakdown voltage becomes high, and the withstand voltage is stably improved over time.
Further, when _{the average primary particle size of BaSO 4} is 500 nm or less, preferably 0.1 to 50% by mass, the space charge is stably suppressed over time. That is, the movement of the space charge inside the urethane-based elastomer when a voltage is applied is _{suppressed by the charge trap by the fine particles of BaSO 4} , and the place where the electric field is locally concentrated is less likely to occur inside.
The lower limit of the average primary particle size is not particularly limited, but it is 1 nm, preferably 5 nm. Those less than 5 nm, especially those less than 1 nm, are difficult to manufacture and obtain.
When the average primary particle size exceeds 500 nm, the effect of suppressing space charge is reduced due to reaggregation during dispersion.
If the blending amount is less than 0.1% by mass, the effect of suppressing space charge is reduced.
When the blending amount exceeds 50% by mass, the hysteresis loss increases.

(2) Dielectric Elastomer Actuator A dielectric elastomer actuator including a dielectric elastomer molded product formed of the dielectric elastomer according to the invention of (1) or a preferred embodiment thereof, and electrode layers arranged on both sides of the dielectric elastomer molded product.

According to the present invention, it is possible to provide a dielectric elastomer suitable for an actuator, including a urethane-based elastomer that is stable over time and has an improved withstand voltage, by blending a specific filler. Further, by specifying the particle size and the blending amount of a specific filler, it is possible to provide a dielectric elastomer suitable for an actuator, which is stable over time and suppresses space charge.

FIG. 1 is an explanatory diagram of a dielectric breakdown test method for a dielectric elastomer film. FIG. 2 is an explanatory diagram of an electromechanical performance test method. FIG. 3 is a graph showing changes in test force in an electromechanical performance test. FIG. 4 is a graph showing the relationship between the blending amount _{of BaSO 4 and the maximum electric field emphasis rate.} FIG. 5 is a graph showing the relationship between the particle size _{of BaSO 4 and the maximum electric field emphasis factor.} FIG. 6 is a graph showing the charge distribution of sample 1. FIG. 7 is a map diagram showing the charge distribution of sample 1. FIG. 8 is a graph showing the charge distribution of sample 6'. FIG. 9 is a map diagram showing the charge distribution of sample 6'. FIG. 10 is a graph showing the charge distribution of sample 7. FIG. 11 is a map diagram showing the charge distribution of the sample 7. FIG. 12 is a graph showing the charge distribution of sample F1 (initial). FIG. 13 is a map diagram showing the charge distribution of sample F1 (initial). FIG. 14 is a graph showing the charge distribution of sample F1 (aging). FIG. 15 is a map diagram showing the charge distribution of sample F1 (aging). FIG. 16 is a graph showing the charge distribution of the sample 11. FIG. 17 is a map diagram showing the charge distribution of the sample 11. FIG. 18 is a graph showing the charge distribution of the sample 13. FIG. 19 is a map diagram showing the charge distribution of the sample 13. FIG. 20 is a graph showing the charge distribution of the sample 15. FIG. 21 is a map diagram showing the charge distribution of the sample 15. FIG. 22 is a graph showing the charge distribution of the sample 17. FIG. 23 is a map diagram showing the charge distribution of the sample 17. FIG. 24 is a cross-sectional view of an actuator using the same dielectric elastomer membrane.

[1] Dielectric Elastomer Molded Body As described above, in the present invention, it is an object of the present invention that urethane-based elastomers are particularly affected by space charges.
Examples of the urethane-based elastomer include crosslinked polyrotaxane in which a polyrotaxane and a crosslinking agent are bonded by a urethane bond, urethane rubber, and the like.
However, the dielectric elastomer molded product may contain a dielectric elastomer other than the urethane-based elastomer. In that case, it is preferable that the urethane-based elastomer is the most elastomer component.
Dielectric elastomers other than urethane-based elastomers are not particularly limited, and examples thereof include silicone elastomers, styrene-based thermoplastic elastomers, natural rubbers, nitrile rubbers, acrylic rubbers, urea rubbers, fluororubbers, and crosslinked polyrotaxans containing no urethane bond.

The form of the dielectric elastomer molded product is not particularly limited, and examples thereof include a film, a wire, a strip, a ring, a rod, and a lump.

In the above, polyrotaxane is a molecular assembly having a structure in which a linear molecule penetrates a cyclic molecule so as to be relatively slidable, and the cyclic molecule is not detached by the blocking groups arranged at both ends of the linear molecule (for example). International Publication No. 2005/080469), also known as a slide ring material. Polyrotaxane is not limited to those having a specific cyclic molecule, a linear molecule, and a blocking group.
Examples of the cyclic molecule include cyclodextrin, crown ether, cyclophane, calixarene, cucurbituril, and cyclic amide.
As linear molecules, polyethers such as polyethylene glycol, polypropylene glycol and poly tetrahydrofuran, polyesters such as polylactic acid, polyamides such as 6-nylon, diene polymers such as polyisobutylene and polybutadiene, polyethylene and polypropylene. , Polyvinyl alcohol, polyvinyl methyl ether, polyisobutylene and other vinyl polymers, polydimethylsiloxane and the like can be exemplified.
Blocking groups include dinitrophenyl groups, cyclodextrins, adamantan groups, trityl groups, fluoresceins, pyrenes, and substituted benzenes (alkyl, alkyloxy, hydroxy, halogen, cyano, sulfonyl, carboxyl as substituents). , Amino, phenyl and the like can be exemplified), polynuclear aromatics which may be substituted (the same as above can be exemplified as the substituent), steroids and the like can be exemplified.
Currently, the most common polyrotaxane uses cyclodextrin as a cyclic molecule and polyethylene glycol as a linear molecule.

The crosslinked polyrotaxane is obtained by cross-linking the cyclic molecules of adjacent polyrotaxanes with a cross-linking agent, and is a dielectric elastomer molded product of a dielectric elastomer actuator due to its high dielectric constant and unique mechanical properties such as viscoelasticity. Suitable for. The cross-linking agent is not limited to a specific one.
Examples of the cross-linking agent include cyanul chloride, trimeoyl chloride, terephthaloyl chloride, epichlorohydrin, dibromobenzene, glutaaldehyde, aliphatic polyfunctional isocyanate, aromatic polyfunctional isocyanate, trilein diisosocyanate, hexamethylene diisocyanate, and divinyl. Block copolymer containing sulfone, 1,1'-carbonyldiimidazole, alkoxysilanes and derivatives thereof, polymers having isocyanates at both ends (for example, polyethylene glycol, polypropylene glycol, etc.), and polysiloxane (poly) Caprolactone-polysiloxane block copolymer, polyadipate-polysiloxane block copolymer, polyethylene glycol-polysiloxane block copolymer, etc.) and the like can be exemplified.

[2] Dielectric Elastomer Actuator In the dielectric elastomer actuator, two or more film-shaped dielectric elastomer molded bodies and three or more electrode layers are alternately arranged (first electrode layer / dielectric elastomer molded body / first) in that a large displacement can be obtained. Two-electrode layer / dielectric elastomer molded product / first electrode layer ...) Laminated ones are preferable.
The number of layers is not particularly limited, but in terms of the number of layers of the dielectric elastomer layer, 2 to 190 is preferable, and 10 to 150 is more preferable.

The electrode layer can be deformed according to the deformation of the dielectric elastomer molded body, and is not particularly limited, but is composed of a conductive film made of conductive particles, a conductive coating film containing conductive particles, and a conductive polymer. Examples thereof include a conductive film, a conductive elastomer molded body containing conductive particles, a liquid metal film, a conductive liquid film, and the like.
Here, the conductive particles are not particularly limited, and examples thereof include particles such as carbon black, carbon nanotubes, platinum, gold, silver, copper, and nickel.
The resin component of the conductive coating film is not particularly limited, and examples thereof include phthalic acid-based, acrylic-based, urethane-based, epoxy-based, and vinyl-based resins.
The elastomer component of the conductive elastomer molded product is not particularly limited, but the dielectric elastomer exemplified in the above [1] can be exemplified.

Hereinafter, examples of the dielectric elastomer embodying the present invention will be described in the following order. The present invention is not limited to the present embodiment.

<1> Preparation of polyrotaxane <2> Preparation of cross-linking agent solution <3> Preparation of elastomer composition solution <4> Preparation of dielectric elastomer film <5> Measurement of physical properties of dielectric elastomer film <6> Evaluation <7> Dielectric Fabrication of elastomer actuators

<1> Preparation of polyrotaxane First, as a polyrotaxane containing cyclodextrin in a cyclic molecule, polyethylene glycol in a linear molecule, and blocking groups arranged at both ends of the linear molecule, International Publication No. 2005 A hydroxypropyl group-modified polyrotaxane (hereinafter sometimes abbreviated as “HAPR”) disclosed in / 080469 was prepared.

Next, in order to obtain solubility and compatibility, a polyrotaxane having a caprolactone group was prepared by the following method. 10 g of the above HAPR was placed in a three-necked flask, and 45 g of ε-caprolactone was introduced while slowly flowing nitrogen. After uniformly stirring at 100 ° C. for 30 minutes with a mechanical stirrer, the reaction temperature was raised to 130 ° C., 1.6 g of tin 2-ethylhexanoate (50 wt% solution) diluted with toluene in advance was added, and the mixture was reacted for 5 hours. , The solvent was removed to obtain 55 g of polyrotaxane (HAPR-g-PCL) having a caprolactone group. The cyclic molecule has polycaprolactone (number of chains: about 35) as a graft chain. Moreover, the weight average molecular weight Mw: 580,000 and the molecular weight distribution Mw / Mn = 1.5 were confirmed by GPC. The hydroxyl value was 72 mgKOH / g as a result of measurement by a method according to JIS K0070-1992.

<2> Preparation of cross-linking agent solution After adding polypropylene glycol 700, diol type (500 g, manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.) and praxel M (430 g, manufactured by Daicel), which is a monomer of ε-caprolactone, to a three-necked eggplant flask. , Stirred in an oil bath at 110 ° C. under a nitrogen stream for 2 hours. After raising the temperature of the oil bath to 130 ° C., tin 2-ethylhexanoate (0.5 g, manufactured by Aldrich) was added and stirred for 10 hours, and polypropylene glycol (oligomer 1) having polycaprolactone grafted on both ends (oligomer 1) ( Mn = 1710) was obtained.
After adding the above oligomer 1 (100 g) to a three-necked eggplant flask, the mixture was stirred in an oil bath at 90 ° C. under a nitrogen stream. Takenate 600 (7.45 g) was slowly added dropwise to this solution over 1 hour, and then the mixture was further stirred for 2 hours to obtain Oligomer 2 (Mn = 3982).
After adding Takenate 600 (16.66 g, manufactured by Mitsui Chemicals, Inc.) to a three-necked eggplant flask, the mixture was stirred under a nitrogen stream in an oil bath at 90 ° C. A solution prepared by dissolving the above oligomer 2 (80 g) in toluene (80 g) was slowly added dropwise to this solution over 2 hours, and then the mixture was further stirred for 2 hours. After the reaction, the liquid temperature was lowered to 40 ° C., and then 2-butanone oxime (10.95 g, manufactured by Tokyo Kasei Co., Ltd.) was slowly added dropwise so that the liquid temperature did not exceed 60 ° C. After the dropwise addition, the mixture was stirred at 40 ° C. for 5 hours to obtain a solution (Mn = 5422) of a cross-linking agent composed of polypropylene glycol having a terminally blocked isocyanate group.

<3> Preparation of Elastomer Composition Solution The elastomer composition solutions of Samples 1 to 17 and F1 to F3 were prepared with the formulations shown in Tables 1, 2 and 3 below (the compounding value is mass (g)).
-Sample 1 does not contain a filler.
_{-Samples 2 to 9 are prepared by blending BaSO 4} having an average primary particle diameter (hereinafter, may be simply referred to as "particle diameter") of 30 nm as a filler, and changing the blending amount.
-Samples F1 to F3 contain different fillers.
-Samples 11, 13, 15 and 17 are _{prepared by blending BaSO 4} as a filler and changing the particle size thereof.

It should be noted that the experiment takes many days, and the characteristics of the dielectric elastomer tend to differ depending on various conditions such as the date and time (temperature, humidity) and lot. Therefore, when the particle size is changed, the conditions are the same as those of the sample 11 and no filler is used. Sample 10, sample 12 under the same conditions as sample 13 and without filler, sample 14 under the same conditions as sample 15 and without filler, and sample 16 under the same conditions as sample 17 and without filler were also performed and compared.
Further, the sample 6 in Table 1 and the sample 6'in Table 2 are experiments of the same composition at different dates and times.

-Polyrotaxane is HAPR-g-PCL prepared in <1> above.
-As the two reaction components, "Polypropylene glycol 700, diol type" manufactured by Wako Junyaku Co., Ltd. was used as it was.
-As one reaction component, "polypropylene glycol 1K, monool type" manufactured by Wako Junyaku Co., Ltd. was used as it was.
-The cross-linking agent solution was prepared in <2> above.
-As an antioxidant, Rianlon Corp. Manufactured by "Thanox 1726" was used.
-Toluene was used as the solvent.

-As the silicone additive, "DBL-C31" manufactured by GELEST (both-terminal alcohol-modified silicone: caprolactone-dimethylsiloxane-caprolactone block copolymer) (solution, solid content 30% by mass) was used.
-Dibutyltin dilaurate (solution) was used as a catalyst (for deprotection).
-As a hydrolysis inhibitor, "Carbodilite V-09GB" (solution, solid content 30% by mass) manufactured by Nisshinbo Chemical Co., Ltd. was used.

・ Filler dispersion (a) BaSO ₄
30 nm: Sakai Chemical Industry Co., Ltd. trade name "Variclear BF-20FS" (BaSO ₄ having a primary particle size of 30 nm dispersed in butyl acetate, solid content 62% by mass) was used as it was as a filler dispersion. ..
100 nm: A product obtained by dispersing the trade name “BARIFINE BF-1L” (particle state) of Sakai Chemical Industry Co., Ltd. in the same manner as the above 30 nm (dispersion medium: butyl acetate, solid content 62% by mass) was used.
300 nm: A product in which the trade name “BARIACE B-34” (particle state) of Sakai Chemical Industry Co., Ltd. was dispersed in the same manner as in the above 30 nm was used.
900 nm: A product obtained by dispersing the trade name “precipitating barium 270” (particle state) of Sakai Chemical Industry Co., Ltd. in the same manner as the above 30 nm was used.
(B) MgO
Using the trade name "SMO-0.1" (average primary particle size 100 nm, particle state) of Sakai Chemical Industry Co., Ltd., those in the particle state were directly mixed without being dispersed in the dispersion medium.
(C) Al ₂ O ₃
Using the trade name "Alu C" (average primary particle diameter 13 nm, particle state) of Nippon Aerosil Co., Ltd., the same direct mixing was performed.
(D) SiO ₂
Using the trade name "R972" (average primary particle diameter 16 nm, particle state) of Nippon Aerosil Co., Ltd., the same direct mixing was performed.

First, polyrotaxane, 2 reaction components, 1 reaction component, a cross-linking agent solution, an antioxidant, and a solvent were stirred to obtain a uniform mixed solution.
Next, a silicon additive, a catalyst, and a hydrolysis inhibitor were added to this mixed solution, and the mixture was stirred to obtain a uniform additive solution.
Further, a filler dispersion was added to this added solution, and the mixture was stirred to prepare a uniform elastomer composition solution.

<4> Preparation of Dielectric Elastomer Film The elastomer composition solution prepared above is thoroughly defoamed, applied to a PET sheet by the slit die coater method, and then placed in an oven at 130 ° C. under reduced pressure for 5 hours. It was cured and peeled off from the PET sheet to prepare a dielectric elastomer film having a thickness of about 0.05 mm (thickness of about 0.1 mm for EMP measurement).

<5> Measurement of Physical Properties of Dielectric Elastomer Film The initial characteristics of the dielectric elastomer membrane of each sample after preparation were measured as follows. The measurement results are shown in Tables 1 to 3 and FIGS. 4 to 13, 16 to 23. In addition, the time-lapse characteristics of sample 6'after 3 months were also measured (table 2, lower part), and the time-lapse characteristics of sample F1 after 4 months were also measured (table 2, lower part, FIGS. 14 and 15).

<5-1> Relative Permittivity Platinum is vapor-deposited on the dielectric elastomer film of each sample using an autofine coater (manufactured by JEC-3000FC JEOL Ltd.) to an inner diameter of 5 mm, and a Permittivity Measurement Analyzer is used. The capacitance was measured and calculated with (4294A, manufactured by Alient Co., Ltd.).

<5-2> Initial elastic modulus, breaking strength and elongation rate The dielectric elastomer film of each sample is processed into a dumbbell type (width 2.04 mm, initial sample length 10 mm), and using "AGS-X 10N" manufactured by Shimazu. , Perform a tensile test at a tensile speed of 0.2 mm / sec, record the stress-strain curve, calculate the initial elastic modulus from the slope that linearly approximates the stress-strain curve from 1% to 5% elongation, and break. The strength and elastic modulus were measured.

<5-3> Hysteresis loss For the hysteresis loss, the strain due to the tensile test of the material was used instead of the deformation of the material in the mechanical energy loss rate (hysteresis loss) in one cycle of deformation and recovery according to JIS K6400. It is a thing.
Specifically, the dielectric elastomer film of each sample is processed into dumbbell No. 7 type (according to JIS K-6251), subjected to a tensile test, and the stress-strain curve is measured. After the elongation extends to 100% of the effective length, it contracts to 0% at the same rate as the elongation. This cycle was performed 10 times, and the average value from 1 to 10 times was calculated as the hysteresis loss by the method of measuring and calculating the area.

<5-4> Dielectric breakdown electric field strength First, the film thickness of the dielectric elastomer film of each sample was measured. Next, as shown in FIG. 1, the dielectric elastomer film 1 is attached to the disk electrode 21 on the installation side, and the cylindrical electrode 22 is placed on the dielectric elastomer film 1, and at this time, the dielectric elastomer film 1 and each of the electrodes 21 and 22 are placed. Care was taken not to leave air bubbles between the two as much as possible, and the air bubbles were further degassed by a vacuum device. This was set in a dielectric breakdown measuring device under normal temperature and humidity, and a voltage was applied between the electrodes 21 and 22 by the power supply device 23 so as to increase the step-up speed at a boosting speed of 10 V / 0.1 second. Then, the dielectric breakdown electric field strength (V / μm) was obtained from the voltage at the time when the current became 1.2 μA or more through the insulated state in which the current substantially did not flow. Normal temperature is 20 ± 15 ° C. and normal humidity is 65 ± 20% (JIS-8703).

<5-5> Electrical resistivity The surface resistivity ρs (Ω / □) and volume resistivity ρv (Ω · cm) of the dielectric elastomer film of each sample are measured using a "super insulation meter SM7120" manufactured by Hioki Electric Co., Ltd. did.

<5-6> Electro mechanical performance (EMP) test A dielectric elastomer film (thickness of about 0.1 mm) of sample 1, 6'(initial) is placed on one side of the negative electrode and on the other side. After providing the positive electrode, the tensile force was measured by "AGS-X 10N" manufactured by Shimadzu Corporation while pulling in the vertical direction with a tensile tester as shown in FIG. Specifically, as shown in FIG. 3, first apply 20% of pre-stretch, hold for 120 seconds in a state of 20% tension, apply voltage (3000 V) as it is, hold for another 420 seconds, and then stop applying voltage. It was held for 60 seconds (600 seconds in total).

<5-7> Measurement of Space Charge by Pulse Electrostatic Stress Method (PEA Method) The charge distribution in the dielectric elastomer film of each sample was measured by a PEA space charge measuring device. Then, as one evaluation index of the space charge, the maximum electric field emphasis factor was calculated as follows. The initial electric field is 3000 [V] (applied voltage) / film thickness [μm].
Maximum electric field enhancement rate = (maximum electric field [V / μm] in 0 to 600 seconds) / (initial electric field [V / μm])
As another evaluation index of space charge, graphs showing the charge distribution of the extracted sample are shown in FIGS. 6,8,10,12,14,16,18,20,22, and the map is shown in FIGS.7,9,11. , 13, 15, 17, 19, 21, 23. 8 and 9 are sample 6'(initial), FIGS. 10 and 11 are sample 7, FIGS. 12 and 13 are sample F1 (initial), FIGS. 14 and 15 are sample F1 (aging), and FIGS. 16 and 17 are sample 11 and FIG. 18 and 19 are the results of sample 13, FIGS. 20 and 21 are the results of sample 15, and FIGS. 22 and 23 are the results of sample 17.
In the graph of FIG. 6 and the like, the horizontal axis is the position in the thickness direction of the dielectric elastomer film (0 μm is one surface in contact with the negative electrode, 100 μm is the other surface in contact with the positive electrode), and the vertical axis is the amount of electric charge. The graph lines of the book are the charge distributions at 1 second, 180 seconds, 360 seconds and 540 seconds, respectively.
In the map of FIG. 7 and the like, the horizontal axis is the same as that of FIG.

<6> Evaluation <6-1> _{Formulation of BaSO 4 As} shown in FIG. 3 showing the results of the electromechanical performance test, in sample 1 (broken line), which is a base material not blended with a filler, the tensile force increases with the passage of time. Although a decrease was observed, in _{sample 6'(solid line) containing BaSO 4} as a filler, the tensile force became constant and the amount of deformation was stabilized.
Further, as shown in Table 1, the sample 1 without the filler had an dielectric breakdown electric field strength of less than 60 V / μm and a surface resistivity of less than 2E + 13. Further, as shown in FIGS. 6 and 7, a negative charge enters the inside of the film from the negative electrode and a positive charge enters from the positive electrode to generate a space charge.
On the other hand, _{as shown in Table 1, the samples 2 to 9 containing BaSO 4} had a high dielectric breakdown electric field strength and a volume resistivity of 2E + 11Ω · cm or more. Further, as shown in FIGS. 8 and 9 (Sample 6') and FIGS. 10 and 11, as shown in FIG. 4, which further shows the maximum electric field emphasis rate of each compounding amount in Table 1, negative charge or positive charge inside the film is shown. Charge ingress was reduced and space charge was suppressed.

<6-2> Mixing _{of fillers other than BaSO 4 In} the initial characteristics of the sample F1 containing MgO, the space charge was suppressed as shown in the middle of Table 2 and FIGS. 12 and 13, but after 4 months had passed. As shown in the lower part of Table 2 and FIGS. 14 and 15, negative charges and positive charges entered the inside of the film.
Further, as shown in Table 2, the space charge of the sample F2 containing _{Al 2} O _{3 and the sample F3 containing SiO 2 was not suppressed due to the initial characteristics.}
On the other hand, _{as shown in Table 2, the sample 6'containing BaSO 4} suppressed the space charge not only in the initial characteristics but also in the aging characteristics after 3 months.

<6-3> sample 11, 13, 15 and 17 having a particle diameter for particle diameter was blended with different BaSO ₄ of BaSO _4, respectively, the sample 10 unfilled stocked conditions as described above <3> Compared with 12, 14 and 16, the dielectric breakdown electric field strength was higher and the volume resistivity was also higher.
FIG. 5 shows the maximum electric field enhancement rates in Table 3 side by side among samples having the same particle size.
As shown in FIGS. 16 and 17 and Table 3, the sample 11 containing _{BaSO 4} having a particle size of 900 nm had a weaker effect of suppressing space charge than the sample 10.
On the other hand, as shown in FIGS. 18 and 19 and Tables 3 and 5, the space charge of the sample 13 containing _{BaSO 4} having a particle size of 300 nm was suppressed as compared with the sample 12.
Similarly, as shown in FIGS. 20 and 21, and Tables 3 and 5, the sample 15 containing _{BaSO 4} having a particle size of 100 nm suppressed the space charge as compared with the sample 14.
Similarly, as shown in FIGS. 22 and 22, and Tables 3 and 5, the sample 17 containing _{BaSO 4} having a particle size of 30 nm suppressed the space charge as compared with the sample 16.

<7> Manufacture of Dielectric Elastomer Actuator As shown in FIG. 24, a plurality of dielectric elastomer films 1 and electrode layers 2 of Examples are alternately laminated and then crimped to form an actuator 10. can do. The electrode layer 2 is composed of a group that is staggered to one side in the left-right direction every other and a group that is staggered to the other side in the left-right direction every other time. When a DC voltage is applied with one group as the positive electrode and the other group as the negative electrode, the dielectric elastomer film 1 contracts in the film thickness direction, and the change in the total height of the actuator 10 due to the contraction can be used as the driving displacement. ..

The present invention is not limited to the above-described embodiment, and can be appropriately modified and embodied without departing from the gist of the invention.

1 Dielectric elastomer film 2 Electrode layer 10 Actuator 21 Disk electrode 22 Cylindrical electrode 23 Power supply

<6-3> sample 11, 13, 15 and 17 having a particle diameter for particle diameter was blended with different BaSO ₄ of BaSO _4, respectively, the sample 10 unfilled stocked conditions as described above <3> Compared with 12, 14 and 16, the dielectric breakdown electric field strength was higher and the volume resistivity was also higher.
FIG. 5 shows the maximum electric field enhancement rates in Table 3 side by side among samples having the same particle size.
As shown in FIGS. 16 and 17 and Table 3, the sample 11 containing _{BaSO 4} having a particle size of 900 nm had a weaker effect of suppressing space charge than the sample 10.
On the other hand, as shown in FIGS. 18 and 19 and Tables 3 and 5, the space charge of the sample 13 containing _{BaSO 4} having a particle size of 300 nm was suppressed as compared with the sample 12.
Similarly, as shown in FIGS. 20 and 21, and Tables 3 and 5, the sample 15 containing _{BaSO 4} having a particle size of 100 nm suppressed the space charge as compared with the sample 14.
Also, sample 17 containing a combination of BaSO ₄ particle size 30nm, as shown in FIG. 22, 24, 32 3 and Tables 3 and 5, as compared with the sample 16, the space charge is suppressed.

Claims (9)

A dielectric elastomer containing a _{urethane-based elastomer and BaSO 4} having an average primary particle size of 1000 nm or less, which is blended as a filler. The dielectric elastomer according to claim 1, wherein the urethane-based elastomer is a crosslinked polyrotaxane. The dielectric elastomer according to claim 1 or 2, wherein the initial elastic modulus of the dielectric elastomer is 0.1 to 10 MPa. The dielectric elastomer according to claim 1 or 2, wherein the initial elastic modulus of the dielectric elastomer is 0.5 to 3 MPa. The dielectric elastomer according to any one of claims 1 to 4, wherein the average primary particle size is 500 nm or less. _{The dielectric elastomer according to claim 5, wherein the blending amount of BaSO 4} with respect to the entire dielectric elastomer is 0.1 to 50% by mass. _{The dielectric elastomer according to claim 5, wherein the blending amount of BaSO 4} with respect to the entire dielectric elastomer is 2 to 20% by mass. The dielectric elastomer according to any one of claims 1 to 7, wherein the volume resistivity of the dielectric elastomer is 2.0E + 11Ω · cm or more. A dielectric elastomer actuator including a dielectric elastomer molded product formed of the dielectric elastomer according to any one of claims 1 to 8 and electrode layers arranged on both sides of the dielectric elastomer molded product.