JP3458148B2 - Carbonaceous powder for electrorheological fluid dispersed phase and electrorheological fluid - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carbonaceous powder suitable as a dispersed phase of an electrorheological fluid whose viscosity is increased by applying a voltage, and an electrorheological fluid using the carbonaceous powder as a dispersed phase.

[0002]

BACKGROUND OF THE INVENTION Electrorheological fluids are suspensions of finely divided hydrophilic solids in a hydrophobic, non-conducting oil, which are very rapidly dispersed under the action of a sufficiently strong electric field. Moreover, the viscosity of the liquid reversibly increases and becomes a solid state. The current required to significantly increase viscosity is very small and DC and AC electric fields can be used, so for example, clutches, hydraulic valves, shock absorbers, vibrators, anti-vibration rubber, or workpieces can be used. It can be used as a component in an electro-mechanical interface or the like for controlling a system for holding in place.

Conventionally, as dispersed phase solid particles which are one of the constituents of electrorheological fluid, cellulose, starch, silica gel, ion exchange resin, lithium polyacrylate, etc., which have been adsorbed with water from the surface and pulverized, As the liquid phase which is another component, it is known to use polychlorinated biphenyl, butyl sebacate, trans oil, chlorinated paraffin, silicone oil, etc. There are still no electrorheological fluids with high performance and stability.

The properties required for a practical electrorheological fluid are that it exhibits a large electrorheological effect, that it consumes little current, that it can be used in a wide temperature range, and that it has long-term stability.

However, in the water-containing electrorheological fluid having the particles having water adsorbed as the dispersed phase as described above, the electric charge carriers that exhibit the electrorheological effect are ions, so that the conductivity is low near room temperature. , The problem that the conductivity becomes significantly high at high temperature and the current consumption becomes very high,
In addition, there is a problem in that at high temperatures, water is vaporized and the electrorheological effect and responsiveness deteriorate. Therefore, the upper limit of the operating temperature of the conventional hydrous electrorheological fluid is about 70 to 80 ° C., and it has not been possible to apply it to the use in a high temperature environment such as an automobile engine room.

As a method for improving the drawbacks of the hydrous electrorheological fluid, a non-aqueous electrorheological fluid using particles containing no water has been proposed. As such a non-aqueous electrorheological fluid, a fluid using organic semiconductor particles such as polyacenequinone as a dispersed phase (Japanese Patent Laid-Open No. 61-216202).
No.) or a dielectric fluid having a conductive thin film layer formed on the surface of organic or inorganic solid particles and further having an electrically insulating thin film layer formed thereon as a dispersed phase (JP-A-63-976).
No. 94, JP-A-1-164823) and the like are known. However, these non-aqueous electrorheological fluids have not been practically used at present because of their lack of long-term stability of characteristics, poor reproducibility, large current consumption, and difficulty in industrial production. Not not.

In JP-A-3-279206, the ratio of the number of carbon atoms to hydrogen atoms (C / H) is 1.70 to 3.5.
0 ° C. and 400 ° C. to 6 under nitrogen atmosphere
The amount of weight loss in the temperature range of 00 ° C is 0.5 to 13.
There has been proposed a carbonaceous powder for electrorheological fluid, which satisfies at least one of the conditions in the range of 0% by weight. This carbonaceous powder uses an organic compound selected from the group consisting of coal, coal-based tar, pitch, coal liquefaction, cokes, petroleum, petroleum-based tar, pitch and resins as a raw material, and has a maximum temperature of 300 to 80.
It is obtained by heat treatment at 0 ° C. An electrorheological fluid using this carbonaceous powder as a dispersed phase has preferable characteristics, but further improvement is desired in terms of current consumption.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a carbonaceous powder capable of further reducing current consumption and an electrorheological fluid using the carbonaceous powder as a dispersed phase.

[0009]

A carbonaceous powder for an electrorheological fluid dispersed phase according to the present invention is a cross-linking agent for a thermoplastic pitch obtained by polymerizing a condensed polycyclic aromatic compound containing naphthalene as a main component with a Lewis acid. It was added and the mixture was heated to those obtained by modifying thermosetting, and further heat-treated if necessary 1.5 the ratio of the number of carbon atoms and water <br/> atom (C / H) Adjust to 3.5 ,
In addition, it is characterized in that the average particle size is adjusted to 0.01 to 50 microns.

In the electrorheological fluid according to the present invention, a crosslinking agent is added to and mixed with a thermoplastic pitch obtained by polymerizing a condensed polycyclic aromatic compound containing naphthalene as a main component with a Lewis acid ,
It is heat- modified by heating and is further heat-treated as necessary to adjust the ratio of the number of carbon atoms and hydrogen atoms (C / H) to 1.
It was adjusted to 5 to 3.5, and the dispersed phase 1-60% by volume consisting of carbonaceous powder in which and adjusted to an average particle diameter of 0.01 to 50 microns, a viscosity at room temperature from 0.65 to 100
It is characterized in that it is composed of 40 to 99% by volume of a liquid phase composed of 0 centistokes (cSt) of electric insulating oil.

As a starting material for producing the carbonaceous powder of the present invention, a thermoplastic pitch obtained by polymerizing a condensed polycyclic aromatic compound containing naphthalene as a main component with a Lewis acid is used. Lewis acids include HF / BF ₃ , Al ₂ O ₃ and Th
O ₂ is exemplified, but a fused polycyclic aromatic compound containing naphthene as a main component and HF / BF ₃ as a Lewis acid is used at 150 ° C.
The softening point obtained by thermal polymerization is 150 to 400 ° C.
100% mesophase pitch in the range is preferred.

The cross-linking agent is preferably dinitronaphthalene or sulfur. Add these crosslinking agents to the pitch ,
By mixing and heating, the pitch is modified to be thermosetting. If necessary, further heat-treat to obtain C / H of 1.5 to 3.5
It was adjusted to, and adjusted to an average particle diameter of 0.01 to 50 microns. When the C / H of the carbonaceous powder is less than 1.50, the carbonaceous powder cannot sufficiently exhibit the function as the dielectric fine particles suitable for the electrorheological fluid, and as a result, the sufficient electrorheological effect cannot be obtained. On the other hand, when the C / H value exceeds 3.50, too much current flows in the electrorheological fluid, which practically reduces energy efficiency.

The average particle size of the carbonaceous powder suitable as the dispersed phase of the electrorheological liquid is in the range of 0.01 to 50 μm,
The range is preferably 0.3 to 10 microns. 0.0
If it is less than 1 micron, the initial viscosity is remarkably increased in the absence of an electric field, and the viscosity change due to the electrorheological effect is small, and if it exceeds 50 micron, sufficient stability as a dispersed phase of the electrorheological fluid cannot be obtained. In order to adjust the particle size, known particle size adjusting means such as crushing using an ordinary crusher such as a jet mill, a ball mill, an automatic mortar, dry classification, wet classification, sieving and the like can be arbitrarily used.

By using the carbonaceous powder thus obtained as a dispersed phase, an electrorheological fluid with low current consumption can be obtained.

Examples of the electrically insulating oil that constitutes the liquid phase include hydrocarbon oils, ester oils, aromatic oils, silicone oils, phosphazene oils, and fluorosilicone oils. These can be used alone or in combination of two or more. Among these electric insulating oils, silicone oils such as polydimethylsiloxane and polymethylphenylsiloxane are excellent in that they can be used even in the state of being in direct contact with a material having rubber-like elasticity, and phosphazene oil has a specific gravity. Is excellent in that it suppresses sedimentation of the dispersed phase.

Furthermore, the dielectric constant is higher than that of dimethyl silicone oil, and the electric resistance is the same as that of dimethyl silicone oil. A copolymer of dimethylsiloxane and 3,3,3-trifluoropropylmethylsiloxane having a volume resistivity of 1 is used.
An oily medium of 0 ¹¹ Ω · cm or more has a high viscosity when an electric field is applied and is excellent in storage stability. The ratio of trifluoropropylmethylsiloxane units in the copolymer is 1
0 to 50 mol%, preferably 20 to 40 mol%, and the proportion of dimethylsiloxane units is 50 to 90 mol%, preferably 60 to 80 mol%. When the ratio of the trifluoropropylmethylsiloxane unit exceeds 50 mol%, electroconductivity of the powder is apt to occur because the conductivity is increased, while 10
If it is less than mol%, the dielectric constant is small and the increase in the electrorheological effect is slight. The volume resistivity of the copolymer constituting the liquid phase is 10 ¹¹ Ω · cm or more, preferably 10 ¹² Ω · cm or more. If it is less than 10 ¹¹ Ω · cm, powder electrophoresis is likely to occur.

Alternatively, in place of the liquid phase comprising the above copolymer, 50 mol% or more and less than 90 mol% of dimethylsiloxane and more than 10 mol% and 50 mol% or less of 3,3,3-trifluoropropylmethyl are used. 3,3,3-trifluoropropylmethylsiloxane units in a mixture of an oily medium which is a copolymer of siloxane and has a volume resistivity of 10 ¹¹ Ω · cm or more and an oily medium which is a homopolymer of dimethylsiloxane. Of the dielectric particles in a liquid phase in which the ratio of the number of 3,3,3-trifluoropropylmethylsiloxane units to the total value of the number of dimethylsiloxane units and the number of dimethylsiloxane units is in the range of 0.1 to 0.5. It may be one in which the phases are suspended. When the ratio of the number of 3,3,3-trifluoropropylmethylsiloxane units to the total value of the number of 3,3,3-trifluoropropylmethylsiloxane units and the number of dimethylsiloxane units in the mixture exceeds 0.5, Since the conductivity increases, electrophoretic migration of the powder is likely to occur. On the other hand, if it is less than 0.1, the dielectric constant is small and the electrorheological effect is slightly increased.

The viscosity of electrically insulating oil is 0.6 at 25 ° C.
A material having a viscosity of 5 to 1000 centistokes (cSt), preferably 10 to 200 cSt is used. If the viscosity of the liquid phase is too low, the volatile content increases and the stability of the liquid phase deteriorates. If the viscosity of the liquid phase is too high, the initial viscosity in the absence of an electric field will be high and the change in viscosity due to the electrorheological effect will be small. The dispersed phase can be efficiently suspended by using an electrically insulating oil having a moderately low viscosity as the liquid phase.

The ratio of the dispersed phase and the liquid phase constituting the electrorheological fluid of the present invention is such that the content of the dispersed phase composed of the carbonaceous powder is 1 to 60% by volume, preferably 14 to 40% by volume. Content of liquid phase consisting of electrical insulating oil is 40 to 99
%, Preferably 60-86% by volume. If the amount of the dispersed phase is less than 1% by volume, the electrorheological effect is small, and if it exceeds 60% by volume, the initial viscosity in the absence of an electric field becomes significantly large.

Further, the electrorheological fluid of the present invention may contain other disperse phase and additives such as a surfactant, a dispersant and an inorganic salt within the range not impairing the effect of the present invention.

Hereinafter, the present invention will be described in more detail with reference to examples.

[0022]

Example 1 Thermoplastic pitch obtained by polymerizing a condensed polycyclic aromatic compound containing naphthalene as a main component with HF / BF ₃ (AR resin AR24 manufactured by Mitsubishi Gas Chemical Co., Inc. (melting temperature: 2
38 ° C, toluene insoluble content: 63%, observation by polarized light microscope: 1
(00% mesophase) was pulverized into powder, and then 5% by weight of dinitronaphthalene was added as a cross-linking agent, and the mixture was mixed with nitrogen in a nitrogen atmosphere.
It heated at 60 degreeC and mixed in the molten state. This was cooled and then pulverized and classified to obtain a thermosetting carbonaceous powder having an average particle diameter of 3.5 μm (measured by a laser diffraction type particle size distribution meter).
The C / H of this carbonaceous powder was measured and found to be 2.32. 26.0% by volume of this carbonaceous powder is 74.0% by volume of a liquid phase component of silicone oil having a viscosity of 10 cSt at 25 ° C. (TSF451-10 manufactured by Toshiba Silicone Co., Ltd.).
It was well dispersed in water to obtain an electrorheological fluid as a suspension.

[0023]

Example 2 Thermoplastic pitch obtained by polymerizing a condensed polycyclic aromatic compound containing naphthalene as a main component with HF / BF ₃ (AR resin AR24 manufactured by Mitsubishi Gas Chemical Co., Inc. (melting temperature: 2
38 ° C, toluene insoluble content: 63%, observation by polarized light microscope: 1
After pulverizing (00% mesophase) into powder, 7% by weight of sulfur was added as a cross-linking agent, heated to 300 ° C. in a nitrogen atmosphere, and mixed in a molten state. After cooling this, a thermosetting carbonaceous powder having an average particle diameter of 2.6 μm (measured by a laser diffraction type particle size distribution meter) was obtained by pulverization and classification. The C / H of this carbonaceous powder was measured and found to be 2.19. 26.0% by volume of this carbonaceous powder was well dispersed in 74.0% by volume of a liquid phase component of silicone oil having a viscosity of 10 cSt at 25 ° C. (TSF451-10 manufactured by Toshiba Silicone Co., Ltd.) as an electrorheological fluid as a suspension. Got

[0024]

Example 3 A thermoplastic pitch obtained by polymerizing a condensed polycyclic aromatic compound containing naphthalene as a main component with HF / BF ₃ (AR resin AR24 manufactured by Mitsubishi Gas Chemical Co., Inc. (melting temperature: 2
38 ° C, toluene insoluble content: 63%, observation by polarized light microscope: 1
(00% mesophase) was pulverized into powder, and then 5% by weight of dinitronaphthalene was added as a cross-linking agent, and the mixture was mixed with nitrogen in a nitrogen atmosphere.
It was heated to 20 ° C. and mixed in a molten state. This was cooled and then pulverized and classified to obtain a thermosetting carbonaceous powder having an average particle size of 3.0 μm (measured by a laser diffraction type particle size distribution meter).
The C / H of this carbonaceous powder was measured and found to be 2.09. When this carbonaceous powder was heat-treated in a nitrogen atmosphere at 380 ° C. for 3 hours, the C / H became 2.35. 26.0% by volume of this carbonaceous powder is a liquid phase component of silicone oil having a viscosity of 10 cSt at 25 ° C. (Toshiba Silicone Co., Ltd.).
TSF451-10) 74.0% by volume was well dispersed to obtain an electrorheological fluid as a suspension.

[0025]

Comparative Example 1 Coal tar containing no free carbon (QI) was used in a 20 liter autoclave.
Heat treated at 0 ° C. in a substantially inert atmosphere. The obtained heat-treated product is tar-based medium oil (boiling range 120-250
Extraction and filtration were performed using (.degree. C.). This extraction / filtration residue was used in a batch-type rotary reactor with an internal volume of 2 liters for 5
A carbonaceous powder was obtained by uniformly reheating under a nitrogen stream of 2.0 liter / min at a temperature of 10 ° C. The carbonaceous powder was further crushed and then adjusted to have an average particle size of 3 μm by using an air classifier. The C / H of the carbonaceous powder thus obtained was 2.4.
It was 2. 26.0% by volume of this carbonaceous powder is a liquid phase component of silicone oil having a viscosity of 10 cSt at 25 ° C. (TSF451-10 manufactured by Toshiba Silicone Co., Ltd.) 74.
An electrorheological fluid was obtained as a suspension that was well dispersed in 0% by volume.

[0026]

[Comparative Example 2] Thermoplastic pitch obtained by polymerizing a condensed polycyclic aromatic compound containing naphthalene as a main component with HF / BF ₃ (AR resin AR24 manufactured by Mitsubishi Gas Chemical Co., Inc. (melting temperature: 2
38 ° C, toluene insoluble content: 63%, observation by polarized light microscope: 1
00% mesophase) was crushed into powder, and then 20
It was made infusible by treating at 0 ° C. for 7 hours. Further, this powder was heated to 370 ° C. at a heating rate of 2 ° C./min in a nitrogen gas atmosphere, held for 1 hour to carbonize, and then naturally cooled. The thus prepared carbonaceous powder had an average particle diameter of 4 μm (measured by a laser diffraction type particle size distribution meter) and C / H of 2.91. 26.0% by volume of this carbonaceous powder is the liquid phase component 2
A silicone oil having a viscosity of 10 cSt at 5 ° C (TSF451-10 manufactured by Toshiba Silicone Co., Ltd.) was well dispersed in 74.0% by volume to obtain an electrorheological fluid as a suspension.

The electrorheological effect was measured for each of the electrorheological fluids obtained in Examples 1 to 3 and Comparative Examples 1 and 2. The electro-viscous effect uses a double cylinder type rotational viscometer,
It was evaluated by a shearing force at a shear rate of 366 sec ⁻¹ and a temperature of 25 ° C. when a DC voltage of 0 to 2 KV / mm was applied between the inner and outer cylinders, and at the same time, the current flowing between the inner and outer cylinders was measured. Table 1 shows the shearing force T ₀ when no voltage is applied, the shearing force T when a voltage of 2 kV / mm is applied, the difference T−T ₀ , and the voltage 2 KV / m.
The current density when m is applied is shown.

Table 1 C / H T ₀ T T-T ₀ current density (g · cm) (g · cm) (g · cm) (μA / cm ² ) Example 1 2.32 16 282 266 3.1 Example 2 2.60 19 312 294 4.5 Example 3 2.35 16 295 279 2.9 Comparative Example 1 2.42 18 232 214 5.6 Comparative Example 2 2.91 18 282 264 5.6

As shown in Table 1, the electrorheological fluids containing the carbonaceous powder of the present invention obtained in Examples 1 to 3 as the dispersed phase have lower current consumption than the electrorheological fluids of Comparative Examples 1 and 2. However, it can be seen that a high ER effect is exhibited.

[0030]

Example 4 Thermoplastic pitch (AR resin AR2 manufactured by Mitsubishi Gas Chemical Co., Inc.) obtained by polymerizing a condensed polycyclic aromatic compound containing naphthalene as a main component with HF / BF ₃ as a catalyst.
4 (melting temperature: 238 ° C., toluene insoluble matter: 63%, polarizing microscope observation: 100% mesophase) was pulverized into powder, and then 5% by weight of dinitronaphthalene was added as a cross-linking agent and heated to 320 ° C. in a nitrogen atmosphere. , Were mixed in the molten state. After cooling, it is pulverized and classified to have an average particle diameter of 3.0 μm.
A thermosetting carbonaceous powder (measured by a laser diffraction type particle size distribution meter) was obtained. The C / H of this carbonaceous powder was measured and found to be 2.09. When this carbonaceous powder was heat-treated in a nitrogen atmosphere at 380 ° C. for 3 hours, the C / H was 2.35.
Became. 30% by volume of this carbonaceous powder was mixed with dimethylsiloxane having a viscosity of 8.7 cSt at 25 ° C. and 3,3,3-.
Copolymer with trifluoropropylmethylsiloxane (ratio of 3,3,3-trifluoropropylmethylsiloxane in the copolymer: 30 mol%, volume resistivity:
1.5 × 10 ¹² Ω · cm, relative permittivity 4.5) 70% by volume
It was well dispersed in water to obtain an electrorheological fluid as a suspension. A voltage of 2 KV / mm was applied to this electrorheological fluid at room temperature, the change in viscosity of the fluid and the current value flowing in the fluid at this time were measured, and the function as the electrorheological fluid was evaluated. The results are shown in Table 2. For the measurement of viscosity, use a double cylinder type rotational viscometer,
Shear rate 366 when a DC electric field is applied between the inner and outer cylinders
The apparent viscosity in / sec was measured.

[0031]

Example 5 The same carbonaceous powder 3 as that used in Example 4
A copolymer of dimethylsiloxane having a viscosity of 8.7 cst at 25 ° C. and 3,3,3-trifluoropropylmethylsiloxane at 0% by volume (a ratio of 3,3,3-trifluoropropylmethylsiloxane in the copolymer) : 30
Mol%, volume resistivity: 1.5 × 10 ¹² Ω · cm, relative dielectric constant: 4.5) 35 volume% and viscosity at 25 ° C. 10
Silicone oil composed of cst polydimethylsiloxane (TSF451-10E manufactured by Toshiba Silicone Co., Ltd.)
(R) Dispersed well in 35% by volume of mixed oil to obtain an electrorheological fluid as a suspension. For this fluid, an electrorheological fluid was evaluated in the same manner as in Example 4. The results are shown in Table 2.

[0032]

Example 6 The same carbonaceous powder 3 as that used in Example 4
0% by volume was well dispersed in 70% by volume of silicone oil (TSF451-10ER manufactured by Toshiba Silicone Co., Ltd.) made of polydimethylsiloxane having a viscosity of 10 cst at 25 ° C. to obtain an electrorheological fluid as a suspension. For this fluid, an electrorheological fluid was evaluated in the same manner as in Example 1. Table 2
The results are shown in.

Table 2 T ₀ T T-T ₀ current density (g · cm) (g · cm) (g · cm) (μA / cm ² ) Example 4 16 694 648 3.57 Example 5 50 590 540 3.11 Example 6 53 467 414 2.75

As is clear from Table 2, the electrorheological fluid having the carbonaceous powder of the present invention as a dispersed phase has a high viscosity when an electric field is applied, and particularly 50 to 90 mol% of dimethyl as an electrically insulating oil which is a dispersion medium. Siloxane and 10 to 50 mol% of 3,
An electrorheological fluid (Example 4) using an oily medium having a volume resistivity of 10 ¹¹ Ω · cm or more as a copolymer with 3,3-trifluoropropylmethylsiloxane (Example 4) or the oily medium and ordinary silicone oil The electrorheological fluid using the mixed oil (No. 5) (Example 5) has a significantly higher viscosity when an electric field is applied than the electrorheological fluid using only ordinary silicone oil (Example 6).

[0035]

EXAMPLE 7 30% by volume of carbonaceous powder similar to that in Example 4 was mixed with dimethylsiloxane similar to that in Example 1 to obtain 3,3,3.
Copolymer of 3-trifluoropropylmethylsiloxane (ratio of 3,3,3-trifluoropropylmethylsiloxane in the copolymer: 30 mol%) Dispersed well in 70% by volume, and electrorheological fluid as a suspension Got This electrorheological fluid was allowed to stand at room temperature in a dry box for a long period of time.
After taking out this electrorheological fluid from the dry box and stirring it sufficiently, a voltage of 2 KV / mm was applied at room temperature, the viscosity change of the fluid at this time and the current value flowing in the fluid were measured, and the function as the electrorheological fluid Was evaluated. Table 2 shows the characteristics immediately after preparation and the characteristic changes after one month.

[0036]

Comparative Example 3 Spin pitch for general-purpose carbon fiber obtained from coal tar pitch in a yield of 35% by weight (melting temperature: 2
70 ° C, toluene insoluble content: 66.2% by weight, polarizing microscope observation: isotropic on the whole surface) was pulverized into a powder, and then 20
It was treated at 0 ° C. for 7 hours. The oxygen content of the powder thus obtained was 5.8% by weight. Further, this powder was heated to 410 ° C. at a heating rate of 2 ° C./min in a nitrogen atmosphere, and
After holding for a time to carbonize, it was naturally cooled. The thus-prepared carbonaceous powder had an average particle size of 4 μm (measured by a laser diffraction type particle size distribution meter) and an oxygen content of 3.4% by weight. 30% by volume of this carbonaceous powder was used as a copolymer of dimethylsiloxane and 3,3,3-trifluoropropylmethylsiloxane as in Example 1 (3,3,3 in the copolymer).
The proportion of 3-trifluoropropylmethylsiloxane: 30 mol%) was well dispersed in 70 vol% to obtain an electrorheological fluid as a suspension. This electrorheological fluid was allowed to stand at room temperature in a dry box for a long period of time. Take this electrorheological fluid out of the dry box, stir it well, and let it stand for 2K at room temperature.
A voltage of V / mm was applied, the change in viscosity of the fluid and the current value flowing in the fluid at this time were measured, and the function as an electrorheological fluid was evaluated. Table 3 shows the characteristics immediately after preparation and the characteristic changes after one month has elapsed.

Table 3 T ₀ T T-T ₀ current density (g · cm) (g · cm) (g · cm) (μA / cm ² ) Example 7 Immediately after preparation 46 694 648 3.57 1 month later 45 690 645 3.35 Comparative Example 3 Immediately after preparation 39 596 557 2.20 1 month later 40 552 512 10.55

From the results shown in Table 3, the electrorheological fluid containing the carbonaceous powder of the present invention as the dispersed phase is excellent in storage stability.

[0039]

The storage stability is superior to that of the carbonaceous powder using other conventional starting materials. In addition, 50 to 90 mol% of dimethyl siloxane and 10 to 5 as electric insulating oil
An electrorheological fluid containing a 0 mol% copolymer of 3,3,3-trifluoropropylmethylsiloxane and an oily medium having a volume resistivity of 10 ¹¹ Ω · cm or more can obtain a high electrorheological effect.

─────────────────────────────────────────────────── ─── Continued Front Page (51) Int.Cl. ⁷ Identification Code FI (C10M 169/04 C10M 107: 50 107: 50 125: 02 125: 02) C10N 20:00 A C10N 20:00 Z 20:02 20:02 20:06 Z 20:06 30:00 Z 30:00 40:14 40:14 60:00 60:00 60:10 60:10 70:00 70:00 (72) Inventor Sea Howard Tokyo 3-1-1 Ogawa Higashimachi, Kodaira-shi, Ltd. Within Bridgestone Research and Development 2nd Division (72) Inventor Mari Miyano 3-1-1 Ogawa Higashi-cho, Kodaira-shi, Tokyo Within Bridgestone R & D 2nd Division (56) Reference Documents JP-A-5-5099 (JP, A) JP-A-4-211499 (JP, A) JP-A-3-124794 (JP, A) JP-A-6-158082 (JP, A) JP-A-3- 279206 (JP, A) JP-A-3-223391 (JP, A) JP-A-5-117634 (JP, A) (58) Survey The field (Int.Cl. ^7, DB name) C10M 125/02 C10M 107/50 C10M 159/04 C10M 159/12 C10M 169/04 C10M 177/00 C10N 20:00 - 20:02 C10N 20:06 C10N 30 : 00 C10N 40:14 C10N 60:00 C10N 60:10 C10N 70:00 C01B 31/02 C10C 3/02

Claims (8)

(57) [Claims] 1. A thermoplastic pitch obtained by polymerizing a condensed polycyclic aromatic compound containing naphthalene as a main component with a Lewis acid, a cross-linking agent being added, mixed, and heated to be modified to be thermosetting. it necessary to further heat treatment the ratio of the number of carbon atoms and hydrogen atoms (C / H) was adjusted to 1.5 to 3.5, is and which was adjusted to an average particle diameter of 0.01 to 50 microns A carbonaceous powder for an electrorheological fluid dispersed phase, characterized by: 2. The softening point of the thermoplastic pitch obtained by heat-polymerizing a condensed polycyclic aromatic compound containing naphthalene as a main component at a temperature of 150 ° C. or higher with HF / BF ₃ as a Lewis acid is 150 to 50 ° C.
The carbonaceous powder for electrorheological fluid dispersed phase according to claim 1, which is 100% mesophase pitch in the range of 400 ° C. 3. The carbonaceous powder for an electrorheological fluid dispersed phase according to claim 1, wherein the crosslinking agent is a dinitro compound or sulfur. 4. A thermoplastic pitch obtained by polymerizing a condensed polycyclic aromatic compound containing naphthalene as a main component with a Lewis acid, a cross-linking agent being added, mixed, and heated to be thermoset-modified. optionally further heat-treated to adjust the ratio of the number of carbon atoms and hydrogen atoms (C / H) to 1.5 to 3.5, it is and which was adjusted to an average particle diameter of 0.01 to 50 microns carbon 1 to 60% by volume of a dispersed phase made of fine powder and 40 to 99% by volume of a liquid phase made of an electrically insulating oil having a viscosity of 0.65 to 1000 centistokes (cSt) at room temperature. Electrorheological fluid. 5. The softening point of the thermoplastic pitch obtained by thermally polymerizing a condensed polycyclic aromatic compound containing naphthalene as a main component at a temperature of 150 ° C. or higher with HF / BF ₃ as a Lewis acid is 150 to 50 ° C.
The electrorheological fluid according to claim 4, which is 100% mesophase pitch in the range of 400 ° C. 6. The electrorheological fluid according to claim 4 or 5, wherein the carbonaceous powder uses a dinitro compound or sulfur as a cross-linking agent. 7. The electrical insulating oil is a copolymer of 50 to 90 mol% dimethylsiloxane and 10 to 50 mol% 3,3,3-trifluoropropylmethylsiloxane, and has a volume resistivity of 10 ¹¹ Ω.multidot. The electrorheological fluid according to claim 4, which is an oily medium having a size of cm or more. 8. The volume resistance of the electrically insulating oil is a copolymer of 50 mol% or more and less than 90 mol% of dimethylsiloxane and more than 10 mol% and not more than 50 mol% of 3,3,3-trifluoropropylmethylsiloxane. A mixture of an oily medium having a rate of 10 ¹¹ Ω · cm or more and an oily medium which is a homopolymer of dimethylsiloxane, and the number of 3,3,3-trifluoropropylmethylsiloxane units and the number of dimethylsiloxane units in the mixture. The ratio of the number of 3,3,3-trifluoropropylmethylsiloxane units to the total value of 0.1 is 0.1
It is the range of -0.5, Claim 5, Claim 5, or Claim 6.
The electrorheological fluid according to.