JPH05209185A - Electroviscous fluid - Google Patents

Abstract

PURPOSE:To obtain an electroviscous fluid having stabilized characteristics hardly causing desorption of dopants by dispersing solid particles having a polymer part, an ionic part, etc., in an electrical insulating oil. CONSTITUTION:The objective electroviscous fluid is obtained by dispersing solid particles composed of a polymer part such as preferably polythienylene having unsaturated bonds, an ionic part composed of a transition metal such as copper, iron or nickel for activating the unsaturated bonds and a counter ionic part composed of a carboxylic acid, a sulfonic acid, etc., for preventing the ionic part from being desorbed and scattered from particle bodies and holding the ionic part in an electrical insulating oil (e.g. a silicone oil).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrorheological fluid, and more specifically, it disperses polarized particles that can be polarized and charged in an electrically insulating dispersion medium, and utilizes the so-called Winslow effect to freely adjust the viscosity of the fluid. The present invention relates to an electrorheological fluid that can be changed to.

[0002]

2. Description of the Related Art An electrorheological fluid (ER fluid) is a suspension in which solid particles are dispersed in insulating oil, which is a so-called electrorheological effect (ER effect) capable of rapidly changing viscosity by the action of an external electric field. ). An ideal ER fluid consumes almost no electric power and can reversibly change its viscosity depending on the magnitude of the electric field, so that it can transfer and absorb energy such as clutches, dampers, shock absorbers, and engine mounts. It can also be used for automobile parts.

Solid particles used in ER fluids include:
Conventionally, polymer electrolytes such as crosslinked polylithium methacrylate and conjugated polymer particles such as polyparaphenylene are known. In the former polymer electrolyte type ER fluid using solid particles, the ER effect is exhibited by adsorbing water in the form of crystal water or adhered water to the solid particles. Therefore, this ER fluid has drawbacks due to water, such as a large increase in current in a high temperature range near 100 ° C. and a decrease in ER effect in a low temperature range near 0 ° C. That is, there was a problem in stability with respect to temperature.

In the latter conjugated polymer type ER fluid, the ER is obtained by adsorbing an electrolyte such as cupric chloride on the particles.
Bring out the effect. Since this system does not require the adsorption of water, its stability over temperature is improved compared to electrolyte systems. However, it was difficult to develop any constant ER effect in this system. This is because when a conjugated polymer is doped, the metal salt that is a dopant is dissolved in a solvent and the polymer is immersed in the solvent. Therefore, the doping amount changes depending on the particle size of the conductive polymer, the surface structure, the immersion time, and the like. It is difficult to strictly control the amount of dope by such an operation.

Further, conventional conjugated polymer type ER fluid particles adsorbing an electrolyte such as cupric chloride are usually used by dispersing them in silicone oil, but the particles settle due to the difference in specific gravity between the particles and the dispersion medium. Therefore, redispersion of particles is required when used as an ER fluid. This is not preferable because it impairs the stability of parts when applying ER fluid to automotive parts. Conventionally, a mixture of silicone oil and fluorine-based insulating oil adjusted to have the same specific gravity as the dispersed particles has been used for the purpose of matching the specific gravities of the dispersed particles and the dispersion medium in order to prevent sedimentation. However, the ER fluid whose specific gravity is adjusted in this way has a new problem that the current density increases by about one digit, the power consumption increases, and the fluid cannot be used at high temperature.

[0006]

Therefore, in view of the above-mentioned drawbacks of the prior art, the object of the present invention is to provide an unsaturated polymer type particle in which the desorption of the dopant hardly occurs and is stable, and the doping amount can be controlled. It is to provide the electrorheological fluid used.

[0007]

An electrorheological fluid in which solid particles according to the present invention are dispersed in an electrically insulating oil is a polymer part in which the solid particles have an unsaturated bond, and the unsaturated bond is activated. It is characterized by having an ion portion having a force to generate and a counter ion portion for holding the ion portion.

The electrically insulating oil according to the present invention is ER
Silicon oil, paraffin chloride, dioctyl phthalate, etc., which are usually used for fluids, which hardly pass an electric current and are suitable for dispersion of particles are used. Any of the above can be used. Further, in the present invention,
You may use the mixture of these and a fluorine-type insulating oil.

The polymer having an unsaturated bond according to the present invention is a polymer having a double bond or a triple bond such as a π bond in the middle of a polymer chain in which carbon or other atoms are connected by a σ bond or the like. Is. As such a polymer, a polymer having a conjugated unsaturated bond in which an unsaturated bond and a saturated bond alternately appear may be used. Examples of such polymers include conductive polymers such as polyacetylene, polyparaphenylene, and polyaniline. Among these, polythienylene and polypyrrole, in which the side chain having an anion group is easily bonded, are particularly suitable.

As the ionic moiety having a force of activating the unsaturated bond, a substance having an electron affinity higher than that of the unsaturated bond is used. The activated state here is a state close to a semiconductor having appropriate conductivity and polarizability. Examples of the ionic portion include transition metal ions such as copper, iron, nickel and cobalt, which may be used in the form of salts such as chloride, fluoride and iodide. Furthermore, in order to adjust the conductivity or the dielectric constant, an unsaturated bond having a small conductivity or a dielectric constant introduced with an alkali metal ion or an alkaline earth metal ion as an ionic portion is mixed with the particles of the present invention and used. Good.

The particles according to the present invention have a structure that prevents the ionic portion having an activating force from being desorbed / dissipated from the particle body. In this structure, a carboxylic acid group, a sulfonic acid group, a phosphoric acid group, a nitric acid group and the like can be mentioned as the counterion part for holding the ionic part. An example of a method for introducing these groups into the unsaturated bond is a method through an alkyl group. Further, a method using a covalent bond with a carbon chain containing an oxygen atom, a nitrogen atom, or the like, or a method using an ionic bond, a coordinate bond, or a charge transfer bond may be used. For example, poly 3-alkyl thienylene and poly N-alkyl pyrrole are typical examples.

The amount of particles added to the ER fluid of the present invention is ER
Although it is one of the factors that determine the degree of effect, it cannot be unconditionally determined because the required viscosity range differs depending on the application and the use conditions. Usually, the weight ratio is around 50%, but it is possible to make it larger or smaller depending on the usage condition.

[0013]

FUNCTION AND EFFECT The particles having an unsaturated bond contained in the ER fluid of the present invention cause a bias in the density of π electrons and the like due to the application of a voltage and cause polarization charge. Polarized charged particles are connected to each other or create a state close to connection, so that the viscosity of the entire fluid is increased. This allows the fluid of the present invention to reversibly change its viscosity by the action of an electric field.

In the particles according to the present invention, the ionic portion having the power to activate the unsaturated bond portion deprives the unsaturated bond in the particle of an electron, etc. to change the electronic structure of the particle and activate the particle. Further, since the counter ion portion holding the ion portion forms a complex with the activated portion, the activated state is kept stable (doped state).

In the particles according to the present invention, the ion portion is fixed to the counter ion in the particles in the dedoped state, and in the doped state, a plurality of these ions form a complex. It is possible to create a stable polarization state without desorbing and leaving the system.

Furthermore, the particles according to the present invention eliminate the need for a poorly reproducible doping operation such as the dipping method which has been conventionally required for conjugated polymer particles, and change the type of the ionic portion which is an activator. By doing so, the doping amount can be uniquely controlled. As described above, according to the present invention, the amount of dope can be controlled, and an excellent electrorheological fluid with a stable ER effect can be obtained. Then, for the purpose of matching the specific gravity of the dispersion medium and the dispersed particles, even when the dispersion medium is a mixture of, for example, silicone oil and fluorine-based insulating oil, from the stable polarization state of the dispersed particles according to the present invention, the current density Can be effectively prevented and the ER effect can be expressed.

[0017]

EXAMPLES In this example, ER fluids were evaluated by yield stress. That is, a double cylinder rheometer (made by Iwamoto Seisakusho) with an inner cylinder of 16 mm in diameter (surface area of 17 cm ² ) and an inner diameter of 18 m.
After inserting the ER fluid between the outer cylinders of m
It was rotated at a speed of 100 rpm. In this state, a DC voltage of 0 to 4 kV was applied between the inner cylinder and the outer cylinder, and the torque applied to the inner cylinder was measured. The measured shear stress was extrapolated to a shear rate of 0 to obtain the yield stress.

Example 1 An aqueous solution prepared by dissolving 10.0 g of sodium 2- (3-thienyl) ethanesulfonate in 52 ml of ion-exchanged water and anhydrous iron (II) chloride 30.5
Nitrogen was blown into an aqueous solution prepared by dissolving 8 g in 28 ml of ion-exchanged water to expel dissolved oxygen in the aqueous solution. After nitrogen substitution, these were mixed under a nitrogen stream and stirred at room temperature for 2 hours. Under a nitrogen atmosphere, under reduced pressure of 20 to 40 mmHg, water was gradually distilled off at 40 to 50 ° C over about 3 hours. Further, 100 ml of ion-exchanged water substituted with nitrogen was added, water was distilled off under the same conditions again, dried under reduced pressure, washed twice with 200 ml of acetone, and dried under reduced pressure. further,
It was dissolved in 200 ml of ion-exchanged water, 330 ml of 1N sodium hydroxide was added, mixed well, and then filtered.

The filtrate was used as an ion exchange resin (Organo IR-1
20B) Proton type and sodium type 400g each
After passing through a column and distilling off under reduced pressure, the residue is ethanol-water (3:
It was washed 3 times with 400 ml of the mixed solvent of 1) and dried under reduced pressure to obtain 8.57 g of sodium poly (2- (3-thienyl) ethanesulfonic acid).

As a comparative example, sodium poly (2- (3-thienyl) ethanesulfonic acid) was synthesized in the same manner as in JP-A-2-189333. 2- (3-
25 ml of thienyl) ethanesulfonic acid sodium salt 5 g
15 g of anhydrous iron (II) chloride was added to water 13.5
An aqueous solution dissolved in ml was added thereto, and the mixture was stirred at room temperature under an argon stream. After 16 hours, it was washed with 2000 ml of acetone and dried under reduced pressure at room temperature.

This was suspended in 50 ml of water, 300 ml of a 0.1 M sodium hydroxide aqueous solution was added, and then 8000
Centrifuged at rpm, passed through 250 g of H ⁺ type ion exchange resin, and further passed through 250 g of Na type ion exchange resin, concentrated to about 50 ml, mixed with 1000 ml of 35 mM sodium hydroxide in methanol, and precipitated. After washing with filtered methanol, vacuum drying was performed at 40 ° C. for 10 hours.
As a result, 500 mg of sodium poly (2- (3-thienyl) ethanesulfonic acid) (Formula 1) was obtained.

[0022]

[Chemical 1]

In this example, water was gradually distilled off while heating immediately after the completion of the polymerization reaction, so that the yield which was 10% in the comparative example could be increased to 85% or more.

Example 2 Poly (2- (3-thienyl))
0.96 g of ethanesulfonic acid) sodium salt was dissolved in 3 ml of ion-exchanged water, and 3.17 g of anhydrous copper chloride was mixed with an aqueous solution of 5 ml of ion-exchanged water. The water was distilled off under reduced pressure and the residue was washed twice with 200 ml of methanol. This was again dissolved in 3 ml of deionized water, and anhydrous copper chloride 3.17 was added.
g was mixed with an aqueous solution dissolved in 5 ml of ion-exchanged water.
Water was distilled off under reduced pressure, washed twice with 200 ml of a mixed solvent of methanol-water (9: 1), and dried under reduced pressure to give poly (2- (3-
Copper (thienyl) ethanesulfonic acid) was obtained.

[0025]

[Chemical 2]

4 g of the copper salt particles were vacuum dried at 70 ° C. for 10 hours and then dispersed in 5 ml of silicone oil having a kinematic viscosity of 20 cs to prepare an electrorheological fluid of this example (Sample N).
o. 2). When an electric field of 2 kV / mm was applied to this at room temperature, the yield stress was 1.0 kPa as shown in Table 1. Also, this property lasted for a long time.

As a comparative example, an electrorheological fluid of a comparative example was prepared by adsorbing 10% of water to sodium polymethacrylate particles and then suspending it in silicone oil at a rate of 15 g / 20 ml (Sample No. R1). .. When an electric field of 2 kV / mm was applied to this at room temperature, a yield stress of 0.71 kPa was shown as shown in Table 1.

Further, as a comparative example, an electrorheological fluid of a comparative example was prepared by mixing 1.5 g of particles in which 1 mol of polyparaphenylene adsorbed cupric chloride at a ratio of 2 mmol was mixed with 10 ml of silicone oil (Sample No. 3). R2). When an electric field of 2 kV / mm was applied to this at room temperature, a yield stress of 0.32 kPa was shown as shown in Table 1. As can be seen from Table 1, this example is an excellent electrorheological fluid having a yield stress about twice that of the comparative example.

(Example 3) Magnesium poly (2- (3-thienyl) ethanesulfonic acid) was obtained in the same manner as in Example 2 using anhydrous magnesium chloride. Using this and the copper salt of Example 2, 1: 1 of poly (2- (3-thienyl) ethanesulfonic acid) copper salt particles and magnesium salt particles.
Mixed particles were prepared. 4 g of the mixed particles were vacuum dried at 70 ° C. for 10 hours and then mixed with 5 ml of silicone oil to prepare an electrorheological fluid of this example (Sample No. 3).
When an electric field of 5 kV / mm was applied to this at room temperature,
As shown in Table 1, the yield stress of 6 kPa was shown. Also, this property lasted for a long time.

As a comparative example, 4 g of particles of a magnesium salt of poly (2- (3-thienyl) ethanesulfonic acid) was vacuum dried at 70 ° C. for 10 hours and then mixed with 5 ml of silicone oil to prepare an electrorheological fluid of this comparative example. Prepared (Sample No. R3). When an electric field of 5 kV / mm was applied to this at room temperature, a yield stress of 0.02 kPa was shown as shown in Table 1.

Further, as a comparative example, No. R1 and N
o. When an electric field of 5 kV / mm was applied to R2 at room temperature, it was 2.5 kPa and 1.0 kPa, respectively, as shown in Table 1.
The yield stress of is shown. As can be seen from Table 1, this example is an excellent electrorheological fluid having a yield stress about 2 to 6 times that of the comparative example.

Example 4 Poly (2- (3-thienyl))
4 g of particles obtained by mixing a copper salt of (ethanesulfonic acid) and a magnesium salt in a ratio of 3: 1 were vacuum dried at 70 ° C. for 10 hours and then dispersed in 5 ml of silicone oil to prepare an electrorheological fluid of this example (Sample No. 4). ). This at room temperature, 5kV
When an electric field of / mm was applied, the yield stress was 4.7 kPa as shown in Table 1. Also, this property lasted for a long time.

As can be seen from Table 1, the electrorheological fluid of this embodiment also has a yield stress several times better than that of R1, R2 and R3. Furthermore, the characteristics of the electrorheological fluid of the present embodiment can be adjusted by changing the mixing ratio with particles having different activation forces in comparison with the third embodiment.

Example 5 I-iodine was added as an oxidizing agent to a potassium salt aqueous solution of N- (4-sulfonylbutyl) pyrrole under a nitrogen stream to polymerize it, and the polymer was repeatedly washed with methanol and vacuum dried. This was added with sodium hydroxide at 0.
It was immersed in a 1M methanol solution for 24 hours, washed repeatedly with methanol, and dried in vacuum at 50 ° C. to obtain a poly (N- (4-sulfonylbutyl) pyrrole) potassium salt. An aqueous solution of cupric chloride (10 g / 40 m
After being soaked in 1) for 72 hours, it was repeatedly washed with water and ethanol, vacuum dried at 50 ° C., and then pulverized to obtain poly (N- (4-sulfonylbutyl) pyrrole) copper salt particles (Chemical Formula 3). .. When 2 gV of this particle was suspended in 2.5 ml of silicone oil (Sample No. 5) and an electric field of 2 kV / mm and 5 kV / mm was applied at room temperature,
The yield stress was 0.7 kPa and 3.5 kPa, respectively (Table 1).

[0035]

[Chemical 3]

Example 6 2.0 g of poly (N- (4-sulfonylbutyl) pyrrole) copper salt particles (specific gravity 1.73) obtained by the same operation as in Example 5 above was converted into silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd.). Silicone oil KF96-CST) and fluorine-based insulating oil (Daikin Kogyo's Daifloyl # 3) mixed oil (mixed volume ratio 14:86) were dispersed in 2.5 ml of fluid, respectively, at room temperature to 2 kV / mm and 4 kV / When an electric field of mm was applied, the yield stress was 0.8 kPa and 2.0, respectively.
It showed kPa.

That is, in this example, the electrorheological fluid of the present invention effectively exhibits the ER effect even in a mixed medium of a silicone oil having a lower specific gravity than the dispersed particles and a fluorine-based insulating oil having a higher specific gravity than the dispersed particles. Is shown. Therefore, in order to stabilize the dispersed state of the electrorheological fluid for a long period of time, the specific gravity of the dispersion medium can be appropriately adjusted to match the specific gravity of the dispersed particles.

[0038]

[Table 1]

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI Technical display location C10N 40:14 (72) Inventor Akane Okada Ai-gun Nagakute-cho, Aichi-gun 1 Toyota Central Research Institute Co., Ltd. (72) Inventor Norio Kurauchi 41 Chuoji, Nagakute-cho, Aichi-gun, Aichi Prefecture

Claims (1)

[Claims] 1. An electrorheological fluid obtained by dispersing solid particles in an electrically insulating oil, wherein the solid particles have a polymer portion having an unsaturated bond, and an ionic portion having a force for activating the unsaturated bond. An electrorheological fluid having a counterion portion for holding the ion portion.