JP3345730B2 - Polyurethane elastomer actuator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyurethane elastomer actuator utilizing the electric field orientation of a polyurethane elastomer having a polycarbonate polyol.

[0002]

2. Description of the Related Art The following materials are conventionally known as piezoelectric materials. It is a piezoelectric ceramic typified by lead zirconate titanate (PZT), a piezoelectric polymer typified by polyvinylidene fluoride (PVDF), or a composite of these.

[0003] Certainly, these are actually used as materials for speakers and headphones, and they show excellent performance for such specific applications.

However, the piezoelectric material has a thickness of 2 m.
In the case of m, a voltage as high as about 10 kV is usually required, and the amount of electrostriction to be driven is not so large, at most about 0.1% or less, so that it is not suitable for use as an actuator.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an actuator which does not require a high voltage and which has a larger displacement when a voltage is applied than a conventional piezoelectric material.

[0006]

In order to solve the above-mentioned problems, a polyurethane elastomer actuator according to the present invention is a polyurethane elastomer having a polycarbonate-based polyol. It is characterized by being oriented in the direction of an electric field.

[0007]

When a DC electric field is applied to the polyurethane elastomer actuator of the present invention, the polycarbonate polyol is oriented in the direction of the electric field, and a change in the conformation of the polymer constituting the polyurethane elastomer is induced. In order to orient the polycarbonate-based polyol in the direction of the electric field, it is necessary to apply a DC electric field, and a voltage for that purpose is about 10 kV (2 mm) required by a conventional piezoelectric material (for example, piezoelectric ceramics).
A high voltage is not required, and a voltage of about 5 kV (2 mm thick) or less can be sufficiently displaced. Further, the electrostriction of the conventional piezoelectric material is at most about 0.1%,
According to the present invention, a displacement of about 0.2% or more is possible.

The polycarbonate polyol is oriented in the direction of an electric field when a DC electric field is applied.
The polycarbonate-based polyol may be a dielectric polyol or one having a substituent having a relatively strong dipole moment.

According to the configuration of the present invention, an anisotropic force is generated at an extremely high speed to cause displacement, and this displacement can be used for actuation. The mechanism in which displacement occurs in the present invention is based on the dielectric property of the polycarbonate polyol oriented in the direction of the electric field, and is based on the orientation caused by the electric field and the change in the conformation of the polymer induced thereby.

Therefore, as a next step, a higher-order structure such as anisotropy of the aggregated state of the polymer chains constituting the polyurethane elastomer is one of the factors that determine the magnitude of actuation. The structural change occurs continuously by the electric field, and the rate of change of the displacement amount generally increases until a voltage of 5 kV (2 mm thickness) is applied. Therefore, the generated force and deformation amount can be controlled by the electric field. This means that the action is constant without depending on the current even when the measurement is performed under the condition of passing the current through the system.

In addition, the fact that the displacement is possible even under the condition that the current does not actually flow (for example, about 1 mA) means that the energy is prevented from being thermally dissipated and the electric energy is converted into the mechanical energy with high efficiency. Suggests that you can. In other words, it is possible to change the shape of the polyurethane elastomer only by molecular orientation in a state where the effective current is substantially zero, and the mechanical deformation energy generated at the time of this displacement can be used for actuation.

[0012]

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

The polyurethane elastomer of this embodiment
The displacement mechanism of the actuator is due to the conformational change of the polymer chain, and the response speed is generally on the order of milliseconds to 100 milliseconds, depending on the inducibility of the polyurethane elastomer. The amount of displacement largely depends on the structure and physical properties caused by the degree of crosslinking inherent to the polyurethane elastomer. Incidentally, the responsiveness is extremely fast as compared with, for example, those involving a chemical reaction such as a conventional charged gel.

[0014] The structural components of the polyurethane elastomer are three components, that is, a component constituting the soft segment and the hard segment, and a curing agent necessary for modifying the physical strength. The function is used for the actuator. Therefore, the driving performance of various related compounds and their combinations by an electric field was examined.

The polyurethane elastomer can be obtained by the following method. That is, the reaction is carried out by a conventionally known method using a polycarbonate-based polyol, an organic polyisocyanate, and a chain extender. For example, a method of reacting this polycarbonate-based polyol with an organic polyisocyanate to obtain a urethane prepolymer and then reacting it with a chain extender, or a so-called one-shot method of simultaneously reacting the three components at a predetermined ratio. And so on. The NCO / OH molar ratio between the polycarbonate polyol and the organic polyisocyanate is preferably in the range of 1.5 to 9.

As the polyisocyanate, 2 is used in the molecule.
As long as it has at least two isocyanate groups,
For example, trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, 2,2,4
-Trimethylhexamethylene diisocyanate, dodecamethylene diisocyanate, 1,3-cyclopentane diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, 4,
4'-methylenebis (cyclohexylisocyanate), 1-methyl-2,4-cyclohexanediisocyanate, 1-methyl-2,6-cyclohexanediisocyanate, 1,3-bis (isocyanatomethyl) cyclohexane, 1,4-bis (isocyanatomethyl ) Cyclohexane, m-phenylene diisocyanate, p-
Phenylene diisocyanate, 1,5-naphthalene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-toluidine diisocyanate, dianidin diisocyanate, 4, 4'-
Diphenyl ether diisocyanate, 1,3-xylylene diisocyanate, ω, ω'-diisocyanate-
Examples thereof include 1,4-diethylbenzene, polymethylene polyfernyl polyisocyanate, and modified isocyanurates, carbodiimides, and burets of these polyisocyanates. These are 1
Only one species may be used, or two or more species may be used in combination.

The polycarbonate-based polyol is obtained by condensation of a conventionally known polyol (polyhydric alcohol) with phosgene, chloroformate, dialkyl carbonate or diallyl carbonate, and has various molecular weights. Particularly preferred as such a polycarbonate-based polyol is one using 1,6-hexanediol, 1,4-butanediol, 1,3-butanediol, neopentyl glycol, or 1,5-pentanediol as the polyol. Having a molecular weight of about 500 to 10,000.

For example, a polycarbonate diol represented by the following general formula (Formula 1):

[0019]

Embedded image

(Wherein, R and R ′ are the same or different, divalent monovalent hydrogen groups having 2 to 10 carbon atoms,
n is an integer. ).

The structure of the polyol portion of the polycarbonate-based urethane prepolymer includes a random copolymer of a polycarbonate-based polyol and a polycaprolactone-based polyol, and a random copolymer of a polycarbonate-based polyol and a polyester-based polyol, in addition to the above-described polycarbonate-based polyol. Polymers, random copolymers of polycarbonate polyols and polyether polyols, or polycarbonate polyols and other polyols, such as polycaprolactone polyols, polyester polyols, and mixtures of polyether polyols, and the like. Each may be used alone or in combination.

In addition, it is possible to use a mixture of one or more of a polyester polyol, a polyether polyol, a polybutadiene polyol and a polyolefin polyol with respect to the polycarbonate polyol.

As the curing agent, those generally used in curing a urethane prepolymer to form a polyurethane elastomer may be used. For example, a polyol compound, a polyamine compound and the like can be mentioned. As the polyol compound, a primary polyol, a secondary polyol,
Any of the polyols may be used. Specifically, trimethylolpropane ("TMP"), ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, propylene glycol, dipropylene Glycol, 1,2-butanediol, 1,3-butanediol, 2,3-butanediol, 1,2-pentanediol, 2,3-pentanediol, 2,5-hexanediol, 2,4-hexanediol , 2-ethyl-1,3
-Hexanediol, cyclohexanediol, 2-ethyl-2- (hydroxymethyl) -1,3-propanediol, N, N-bis (2-hydroxypropyl) aniline, hydroquinone-bis- (β-hydroxyethyl)
Ether, resorcinol-bis (β-hydroxyethyl) ether and the like. As the polyamine compound, any of primary amine, secondary amine, and tertiary amine such as diamine, triamine, and tetraamine can be used. Specifically, aliphatic amines such as hexamethylenediamine, alicyclic amines such as 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane, 4,4'-methylenebis-2-chloroaniline, 2,2 '3,3'-tetrachloro-4,4'-diaminophenylmethane, 4,
Aromatic amines such as 4′-diaminodiphenyl, 1,2-bis (2-aminophenylthio) methane, trimethylene glycol paraaminobenzoate, and 2,4,6-tris (dimethylaminomethyl) phenol are exemplified. These curing agents may be used alone or in combination of two or more.

As a method for mixing the above-mentioned curing agent and the urethane prepolymer obtained from the above composition and curing the urethane prepolymer, mixing ratio of the curing agent to the urethane prepolymer, curing temperature, curing time, etc. And can be performed by a known method.

The polyurethane elastomer used in this embodiment may contain additives and the like. Additives include, for example, nonionic plasticizers, flame retardants, fillers, stabilizers, colorants, and the like.

Examples of the plasticizer include dioctyl phthalate (“DOP”), dibutyl phthalate (“DBP”),
Dioctyl adipate ("DOA"), triethylene glycol dibenzoate, tricresyl phosphate,
Dioctyl phthalate, fatty acid ester of pentaeristol, dioctyl sebacate, diisooctyl azelate, dibutoxyethoxyethyl adipate and the like can be used.

After molding a large number of polyurethane elastomers having the above-mentioned composition combinations into a plate having a thickness of 2 mm, a DC electric field was applied thereto and the mechanical response thereof was measured using a strain sensor. That is, the upper and lower surfaces of the polyurethane elastomer molded into a plate shape were sandwiched between electrode plates, and a voltage was applied. The change in thickness of the polyurethane / elastomer was observed with a strain sensor, and the effects of potential and current were measured.

Hereinafter, specific examples will be described. Each example was performed according to the following procedure. A polyisocyanate component (hereinafter referred to as (2)) is added to 100 parts by weight of a polycarbonate-based polyol component (hereinafter referred to as (1)), and the mixture is reacted at 85 ° C. for 1 hour under a nitrogen stream to obtain a urethane prepolymer having a terminal isocyanate group. obtain.

The urethane prepolymer was measured for isocyanate group (“NCO”) content and viscosity at 80 ° C. (shown in Table 1). The viscosity of the urethane prepolymer was determined using a Haake rotational viscometer, Rotovisco RV-12.

100 parts by weight of the urethane prepolymer obtained as described above is kept at 80 ° C. and a curing agent (hereinafter referred to as (3)
Was melted and mixed, poured into a 2 mm-thick mold kept at 110 ° C. in advance, and left in an oven at 110 ° C. for 16 hours to complete the curing reaction. And hardness (JIS-A) was measured (shown in Table 1). here,
The melting temperature when using 4,4′-methylenebis (dichloroaniline) as a curing agent was 140 ° C., and when using other curing agents, the melting temperature was 80 ° C. Example 1 (1) Average molecular weight (refers to number average molecular weight; the same applies hereinafter)
Is 2,055 polycarbonate polyol (Nipporan 980, manufactured by Nippon Polyurethane Industry Co., Ltd.)
R, hereinafter the same). (2) Paraphenylene diisocyanate (PPDI,
DuPont product name, Hiren, the same applies hereinafter) ... 15.8
Parts by weight. (3) 4,4'-methylenebis (dichloroaniline)
(Manufactured by Ihara Chemical Industry Co., Ltd., TCDAM, the same applies hereinafter) ... 15.3 parts by weight. Example 2 (1) The Nipporan 980R (see Example 1),
Polytetramethylene ether glycol having an average molecular weight of 1,986 (trade name PTG, manufactured by Hodogaya Chemical Industry Co., Ltd.)
2000SN) and 7: 3. (2) The PPDI (paraphenylene diisocyanate, see Example 1) 15.9 parts by weight. (3) The TCDAM (4,4'-methylenebis (dichloroaniline), see Example 1) 14.6 parts by weight. Example 3 (1) A random copolymer of a polycarbonate-based polyol and a polycaprolactone-based polyol having an average molecular weight of 2,014 (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name: Nipporan 982R, the same applies hereinafter) and the Nipporan 98
OR (see Example 1) at 7.5: 2.5. (2) The PPDI (paraphenylene diisocyanate, see Example 1) 15.9 parts by weight. (3) The TCDAM (4,4'-methylenebis (dichloroaniline), see Example 1) 15.0 parts by weight. Example 4 (1) The Nipporan 982R (see Example 3). (2) The PPDI (paraphenylenediisocyanate, see Example 1) ... 16.0 parts by weight. (3) The TCDAM (4,4'-methylenebis (dichloroaniline), see Example 1) 14.9 parts by weight. Example 5 (1) The Nipporan 980R (see Example 1),
A polycaprolactone-based polyol having an average molecular weight of 2,000 (Placcel 220N, manufactured by Daicel Chemical Industries, Ltd.) is blended at a ratio of 4: 1. (2) The PPDI (paraphenylene diisocyanate, see Example 1): 15.6 parts by weight. (3) The TCDAM (4,4'-methylenebis (dichloroaniline), see Example 1) 14.0 parts by weight. Example 6 (1) The Nipporan 982R (see Example 3). (2) The PPDI (paraphenylenediisocyanate, see Example 1) ... 16.0 parts by weight. (3) Hydroquinone-bis- (β-hydroxyethyl) ether (manufactured by Eastman, trade name HQEE, the same applies hereinafter): 8.8 parts by weight. Example 7 (1) Polycarbonate-based polyol having an average molecular weight of 1,892 (HYDOL-ODX2398, manufactured by Dainippon Ink and Chemicals, Incorporated). (2) The PPDI (paraphenylene diisocyanate, see Example 1) 16.8 parts by weight. (3) 1,4-butanediol (1,4-BD, manufactured by Kanto Chemical Co., Ltd .; the same applies hereinafter): 4.1 parts by weight. Example 8 (1) The above-mentioned HYDOL-ODX2398 (see Example 7). (2) Tolylene diisocyanate (TDI, manufactured by Nippon Polyurethane Industry Co., Ltd., trade name Coronate T-10)
0, the same applies hereinafter) ... 16.6 parts by weight. (3) 4,4'-methylenebis-2-chloroaniline (MOCA, manufactured by Ihara Chemical Industry Co., Ltd., trade name: Kureamine MT, the same applies hereinafter): 10.6 parts by weight. Example 9 (1) The Nipporan 980R (see Example 1),
Polytetramethylene ether glycol having an average molecular weight of 1,415 (PTG manufactured by Hodogaya Chemical Industry Co., Ltd.
1400SN, the same applies hereinafter) at a ratio of 6: 4. (2) 4,4'-diphenylmethane diisocyanate (MDI, manufactured by Nippon Polyurethane Industry Co., Ltd., trade name: Millionate MT, the same applies hereinafter): 29.0 parts by weight. (3) 5.9 parts by weight of the HQEE (see Example 6) and 2.4 parts by weight of the 1,4-BD (see Example 7). Example 10 (1) The Nipporan 980R (see Example 1),
The PTG1400SN (see Example 9) was blended at a ratio of 6: 4. (2) The MDI (see Example 9): 29.0 parts by weight. (3) The HQEE (see Example 6): 11.1 parts by weight.

The dimensions, shape and measurement conditions of the elastomer molded as described above are as follows. Elastomer dimensions: length 25 mm x width 25 mm x thickness 2 mm. Elastomer shape: Flat, plate-like, with rubber-like elasticity. Applied voltage: 0.5 kV, 1.0 kV, 1.5 kV,
2.0 kV, 2.5 kV, 3.0 kV, 3.5 kV,
4.0 kV, 4.5 kV, 5.0 kV. Shrinkage: The change in the thickness of the sample was measured with a laser displacement meter.

The shrinkage ratio (%) is the amount of shrinkage displacement when voltage is applied as a ratio to the thickness (2 mm) of the sample before voltage application. Exotherm: No exotherm was observed throughout each example. The temperature of the elastomer was measured with a thermocouple inserted into the elastomer.

Table 1 and the graphs shown in the drawings show the measurement results and the like of the polyurethane elastomer actuator in each example. The graph shows the applied voltage (kV)
(K = 0.2 cm) divided by the electric field (k
V / cm) on the horizontal axis, and the shrinkage (%) on the vertical axis.

[0034]

[Table 1]

As shown in the results of each measurement, each of the examples obtained a large amount of displacement even when a low electric field of 5.0 kV or less was applied, and therefore, even under a condition in which a dielectric breakdown did not occur and a current value was hardly observed. There is an advantage that it can be.
That is, displacement with low voltage, that is, low energy is possible.

The voltage is 5.0 kV (electric field 25 kV /
According to the graph (FIG. 1) of the amount of displacement of the elastomer in the direction of the electric field of each of the examples observed in the process of applying the pressure up to the order of cm. That is, when a voltage of 5.0 kV is applied (electric field of 25 kV /
cm), the rate of change of the displacement amount generally increases.

In each embodiment, in the fifth embodiment, 5.0.
Upon application of an electric field of kV (electric field of 25 kV / cm), a rapid shrinkage of 1.95% was observed in the direction of the electric field. On the other hand, the driving amount of the piezoelectric material polyvinylidene fluoride film of the comparative example under the same conditions is 0.1% or less. That is,
When an electric field of 5.0 kV is applied, the driving amount of the device of Example 5 is slightly less than 200 times that of the comparative example.

Unlike the conventional piezoelectric ceramics represented by lead zirconate titanate (PZT), the piezoelectric polymers represented by polyvinylidene fluoride (PVDF), or the composites thereof, Has the advantage that it functions as a soft material. The hardness of the JIS-A value in each example is 80.
From about 94 to a high elastic modulus as an elastomer material, it can be said that it has excellent mechanical properties and large driving force. That is, this embodiment has suitable suitability as an actuator.

According to this embodiment, the application of a direct current electric field orients the dielectric polycarbonate-based polyol component in the direction of the electric field, and utilizes the fact that the structure of the elastomer changes anisotropically. The shape of the elastomer can be changed only by molecular orientation in a state near practically zero (that is, while minimizing heat generation), and the mechanical deformation energy generated during this shape change can be used as actuation. it can. It is considered that the reason why almost no electrolysis or heat generation is involved when displacing the one of this example is that no chemical reaction is involved when the polycarbonate-based polyol is oriented in the electric field direction.

The polyurethane elastomer of this embodiment
Actuators are not driven by grain boundaries as in piezoelectric ceramics, but are fundamentally different in principle and are attributed to the electric field orientation of the soft segment dipoles that make up the amorphous regions of polyurethane elastomers . In other words, it can be said that the driving principle of this is based on a novel driving principle completely different from the conventionally known oriented crystallization PVDF and the phenomenon of distortion due to the electric field at the crystal grain boundaries.

Further, since the behavior of each soft segment becomes a distortion of the entire polyurethane elastomer actuator, a large force can be generated. further,
Since the polyurethane elastomer is an elastic body and soft, an actuator having high processability can be obtained. Since this polyurethane elastomer actuator can be made into a micro-machine by fine processing, it can be applied to a manipulator used for a micro-surgery or the like that requires high precision, soft and fine action. In addition, by changing the combination of the chemical composition of the polyurethane elastomer, an actuator having an extremely large driving amount can be created.

In the case of a gel material, for example, the fact that the drive performance can be obtained only by controlling the polymer structure in a state where the solvent required is not contained at all does not mean that the polyurethane elastomer material is a versatile material. This is a huge advantage when considered.

[0043]

As described above, the present invention has the following effects.

It is possible to provide an actuator which does not require a high voltage and which has a larger displacement when a voltage is applied than a conventional piezoelectric material.

[Brief description of the drawings]

FIG. 1 is a graph showing the contraction rate in the electric field direction of each example observed in a process in which a voltage of up to 5.0 kV was applied to a sample having a thickness of 2 mm.

Continuing from the front page (72) Inventor Shinichiro Kawahara 172 Ikezawa-cho, Yamatokoriyama-shi, Nara Prefecture Nita Plant Inside Nara Plant (72) Inventor Toshihiro Hirai 940-940 Suwa-gata, Ueda-shi, Nagano (56) References JP Hei 5-136475 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 41/08

Claims (1)

(57) [Claims] 1. A polyurethane elastomer actuator having a polycarbonate-based polyol, wherein the polycarbonate-based polyol is oriented in the direction of an electric field when a DC electric field is applied.