EP0341737A1 - Elektroviskose Flüssigkeiten - Google Patents

Elektroviskose Flüssigkeiten Download PDF

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Publication number
EP0341737A1
EP0341737A1 EP89108600A EP89108600A EP0341737A1 EP 0341737 A1 EP0341737 A1 EP 0341737A1 EP 89108600 A EP89108600 A EP 89108600A EP 89108600 A EP89108600 A EP 89108600A EP 0341737 A1 EP0341737 A1 EP 0341737A1
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EP
European Patent Office
Prior art keywords
electroviscous fluid
fluid according
electrolytic solution
particles
electroviscous
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Application number
EP89108600A
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English (en)
French (fr)
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EP0341737B1 (de
Inventor
Eiji Mitsubishi Kasei Corporation Hattori
Yasuo Mitsubishi Kasai Corporation Oguri
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Mitsubishi Kasei Corp
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Mitsubishi Kasei Corp
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Publication of EP0341737A1 publication Critical patent/EP0341737A1/de
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B3/00—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties
    • H01B3/18—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances
    • H01B3/20—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances liquids, e.g. oils
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M171/00—Lubricating compositions characterised by purely physical criteria, e.g. containing as base-material, thickener or additive, ingredients which are characterised exclusively by their numerically specified physical properties, i.e. containing ingredients which are physically well-defined but for which the chemical nature is either unspecified or only very vaguely indicated
    • C10M171/001—Electrorheological fluids; smart fluids
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M125/00—Lubricating compositions characterised by the additive being an inorganic material
    • C10M125/26—Compounds containing silicon or boron, e.g. silica, sand
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M171/00—Lubricating compositions characterised by purely physical criteria, e.g. containing as base-material, thickener or additive, ingredients which are characterised exclusively by their numerically specified physical properties, i.e. containing ingredients which are physically well-defined but for which the chemical nature is either unspecified or only very vaguely indicated

Definitions

  • the present invention relates to an electroviscous fluid.
  • the electroviscous fluid is a fluid showing a so-­called electroviscous effect, whereby the apparent viscosity changes quickly and reversibly by the action of applied voltage (off, on, a change in the voltage).
  • a fluid obtained by vigorously stirring an electrical insulating liquid, fine particles containing or having adsorbed ions and a small amount of water has been known as one of electroviscous fluids.
  • pulverized silica particles have been used as inorganic fine particles, since they are readily available.
  • a cratch, hydrauric valve, vibration damping device, vibrator or the like wherein the electroviscous fluid is used, it is common to utilize the viscosity change of the fluid when the fluid passes through a space between a pair of electrodes for the application of an electric field. Accordingly, abrasion between the particles as the dispersed phase and the wall of the apparatus creates a problem.
  • particles form a cross-­linking structure when a voltage is applied across the electrodes. Accordingly, in the case of pulverized particles, sharp edges of the particles are in contact with one another, whereby there has been a drawback that the dielectric strength tends to be low.
  • the object can be readily accomplished by an electroviscous fluid comprising an electrical insulating liquid and fine particles dispersed therein, wherein the fine particles are spherical particles containing an electrolytic solution, obtained by hydrolysis and polycondensation of a metal alkoxide or its derivative.
  • the electroviscous fluid of the present invention employs fine particles dispersed in an insulating liquid, which are spherical particles having an average particle size of from 0.05 to 2 ⁇ m obtained by hydrolysis and polycondensation of a metal alkoxide or its derivative.
  • a metal alkoxide various alkoxides disclosed in "Metal Alkoxides, edited by D. C. Bradley. R. C. Mehrotra, D. P. Gaur, Academic Press, 1978" may be employed.
  • a preferable alkoxide is composed of lower alkoxy groups of one type or in combination, such as methoxy, ethoxy, propoxy and/or butoxy.
  • Typical examples include alkoxides of e.g. Si, Ti and Zr, and composite alkoxides of e.g. Ba-Ti, Sr-Ti, Pb-Ti, Pb-Ti-Zr and Li-­Nb.
  • the hydrolysis of a metal alkoxide is usually conducted by mixing an alcohol solution of an alkoxide with an aqueous alcohol solution.
  • an amorphous substance of metal oxide can be precipitated substantially in the form of spherical particles.
  • the hydrolyzing rate can usually be adjusted by controlling e.g. the molar ratios and concentrations of the alkoxide and water in the reaction system, and the amount of the catalyst (such as an alkali or acid) for hydrolysis which may be added as the case requires.
  • the conditions to obtain spherical particles can not generally be defined, since they vary depending upon the type of the alkoxide. However, in the case of e.g.
  • the molar ratio of water to the alkoxide is usually from 1 to 150, preferably from 1 to 100, the concentration of the alkoxide is usually from 0.05 to 10 mol/l, preferably from 0.05 dto 5 mol/l, and the concentration of water is usually from 0.1 to 20 mol/l, preferably from 0.1 to 10 mol/l.
  • Figure 1 shows a scanning electron microscopic photograph (10,000 magnification) of spherical particles of silica obtained by hydrolysis of Si(OC2H5)4 in Example 1. As is evident from the Figure, each particle is spherical, and the particle size distribution is sharp.
  • Spherical silica particles are obtained by separating the solid content from the alcohol solution by filtration or centrifugal separation, followed by drying by means of e.g. a rotary evaporator and have an average particle size within a range of from 0.05 to 2 ⁇ m.
  • the above spherical particles contain an electrolytic solution, and the electroviscous effect will be obtained by ions in the solution in accordance with the principle as described above.
  • the electrolyte constituting the electrolytic solution so long as it dissociates ions in a polar solvent such as water.
  • the electrolyte may be an inorganic compound such as NH3, NaOH, NaCl, LiCl, B2O3, Ca(OH)2, MgSO4, Fe(NO3)2 or an ionic surfactant such as sodium sulfonate, sodium carboxylate, sodium alkylbenzene sulfonate, sodium polystyrene sulfonate, a calcium salt of fatty acid or a condensation product of naphthalene sulfonic acid with formalin.
  • Any polar solvent may be used as the solvent constituting the electrolytic solution, so long as it is capable of adequately dissolving the electrolyte used.
  • the concentration and the content of the electrolytic solution may be suitably selected within the respective ranges not to conduct electricity when the electric field is applied.
  • the concentration is selected usually within a range of from 0.1 to 90% by weight, preferably from 5 to 50% by weight.
  • the content is selected usually within a range of from 0.1 to 20% by weight, preferably from 1 to 10% by weight.
  • the hydrolysis and polycondensation of a metal alkoxide can be conducted in the presence a catalyst such as NH3.
  • the catalyst can be used by itself as the electrolyte. Namely, after the hydrolysis and polycondensation of a metal alkoxide, spherical silica particles are separated from the alcohol solution and dried. If this drying is not completely conducted but conducted to such an extent that the weight reduction by heating in air upto 200°C would be from 0.1 to 20% by weight, preferably from 1 to 10% by weight, it is possible to obtain spherical particles containing an electrolytic solution within the above-mentioned range.
  • the above-mentioned weight reduction under heating is a value obtained by a differential thermal analysis at a temperature raising rate of 10°C/min.
  • the polar solvent having a high boling point to be used for this purpose includes glycol (such as ethylene glycol and propylene glycol) and ethanolamine. Among them, ethylene glycol is preferably employed.
  • the spherical particles, the electrolyte, the polar solvent and the electrical insulating liquid may be mixed for a few hours in e.g. a ball mill, or spherical particles may be impregnated in an electrolyte solution.
  • the electrical insulating liquid a liquid capable of dispersing the spherical particles in a stabilized state, which has a high insulation resistance and which does not dissolve the electrolyte solution, is used.
  • a liquid capable of dispersing the spherical particles in a stabilized state which has a high insulation resistance and which does not dissolve the electrolyte solution.
  • it is suitably selected from silicone oil, trans oil, engine oil, an ester, paraffin, an olefin and an aromatic hydrocarbon.
  • the amount of the spherical particles in the electroviscous fluid is usually from 5 to 50%, perferably from 10 to 40%.
  • a ball mill or a usual mixing and dispersing machine such as a ultrasonic dispersing machine, may be used.
  • the electroviscous effect may be measured by using a coaxial double cylinder type rotary viscometer, and an increase in the shearing stress is measured at the same shearing speed (162 sec ⁇ 1) when a voltage is applied across outer and inner cylinders, and the increase is converted to the change in viscosity.
  • the fluidity can be controlled by the applied voltage.
  • the mechatronics field of computer control is expected.
  • Some examples of the practical application will be mentioned.
  • it may be applied to a cratch, a torque converter, a valve, a shock absorber, a brake system or a power steering.
  • it is now being applied to various actuators.
  • Solution A obtained by dissolving 186.0 g of Si(OC2H5)4 (guaranteed reagent grade) in 670.7 g of ethyl alcohol (guaranteed reagent grade) and solution B obtained by dissolving 223.6 g of a 28% NH4OH aqueous solution and 173.9 g of water in 1,999.5 g of ethyl alcohol, were mixed to precipitate silica particles having a diameter of 0.56 ⁇ m. The standard deviation from the particle diameter was 1.05. The particles were separated from this slurry by a conventional method and vacuum-dried at 100°C for one hour to obtain particles in a power form.
  • the particles contained NH3 (1.3 wt%), water (4.1 wt%) and ethanol (0.6 wt%), and the weight reduction was 6% when it was heated in air at 200°C. Then, 30.1 g of the particles were added to 32.8 g of silicone oil (Toray silicone SH200, 10cs), and the mixutre was dispersed and mixed for 12 hours in a ball mill.
  • silicone oil Toray silicone SH200, 10cs
  • the shearing stress was measured by using a coaxial double cylinder type rotary viscometer (electrode distance: 1 mm, temperature: 25°C) at the same shearing speed (162 sec ⁇ 1) when a voltage was applied across the inner and outer cylinders.
  • the results thereby obtained are shown in Figure 2. It is evident that when an electric field 2 kv/mm was applied, the initial viscosity of 1.7 poise increased to a level of 28 poise. This liquid was left to stand at room temperature, and the measurement was conducted 10 days layer, whereby no change in the properties was observed.
  • Spherical silica particles as used in Example 1 were preliminarily heated at 250°C for 16 hours to adequately remove NH3, water and ethanol to obtain 40 g of particles. Then, 48 g of a 5.5% NaOH aqueous solution was added thereto, and the mixture was vacuum-dried at 100°C for one hour to obtain particles in a power form. The particles contained NaOH (5.2 wt%) and water (9.7 wt%), and the weight reduction was 9.7% when heated in air at 200°C. Then, 30.1 g of the particles were added to 32.8 g of silicone oil (Toray silicone SH200, 10cs), and the mixture was dispersed and mixed for 12 hours in a ball mill. The initial viscosity of the crude thus obtained was 1.5 poise, and when an electric field of 2 kv/mm was applied, the viscosity increased to 16 poise (162 sec ⁇ 1).
  • silicone oil Toray silicone SH200, 10cs
  • Spherical silica particles as used in Example 1 were preliminarily heated at 250°C for 16 hours to adequately remove NH3, water and ethanol. Then, 10.0 g of silica particles thus obtained and 0.9 g of aqueous ammonia (NH3 concentration: 25%) were added to 18.7 g of silicone oil (Toray silicone SH200, 10cs), and the mixture was dispersed and mixed for 12 hours in a ball mill. the initial viscosity of the fluid thus obtained was 0.2 poise, and when an electric field of 1.8 kv/mm was applied, the viscosity increased to 22 poise (162 sec ⁇ 1).
  • silicone oil Toray silicone SH200, 10cs
  • Spherical silica particles as used in Example 1 were preliminarily heated at 250°C for 16 hours to adequately remove NH3, water and ethanol. Then, 10.0 g of the silica particles thus obtained and 1.3 g of an aqueous NaOH solution (NaOH concentration: 44%) were added to 18.7 g of silicone oil (Toray silicone SH200, 10cs), and the mixture was dispersed and mixed for 12 hours in a ball mill. The initial viscosity of the fluid thus obtained was 0.3 poise, and when an electric field of 2 kv/mm was applied, the viscosity increased to 16 poise (162 sec ⁇ 1).
  • Spherical silica particles as used in Example 1 were preliminarily heated at 250°C for 16 hours to adequately remove NH3, water and ethanol. Then, 10.0 g of the silica particles thus obtained and 0.7 g of a solution of NaOH in ethylene glycol (NaOH concentration: 1.8%) were added to 18.7 g of silicone oil (Toray silicone SH200, 10cs), and the mixture was dispersed and mixed for 12 hours in a ball mill. The initial viscosity of the fluid thus obtained was 0.8 poise, and when an electric field of 2 kv/mm was applied, the viscosity increased to 17 poise (162 sec ⁇ 1).
  • Example 20.0 g of spherical silica particles as used in Example 1 were added to 37.1 g of dioctyl adipate (C8H17OOC(CH2)4COOC8H17), and the mixture was dispersed and mixed for 12 hours in a ball mill.
  • the initial viscosity of the fluid thus obtained was 0.6 poise, and when an electric field of 2 kv/mm was applied, the viscosity increased to 25 poise (162 sec ⁇ 1).
  • Example 2 20.0 g of spherial silica particles as used in Example 1 were added to 39.4 g of dioctyl phthalate and the mixture was dispersed and mixed for 12 hours in a ball mill.
  • the initial viscosity of the fluid thus obtained was 1.1 poise, and when an electric field of 2 kv/mm was applied, the viscosity increased to 37 poise (162 sec ⁇ 1).
  • Example 2 20.0 g of spherical silica particles as used in Example 1 were added to a mixture of 7.0 g of a hydrocarbon-type low viscosity mineral oil (Mitsubishi Oil RO-2, 2cs) and 33.4 g of silicone oil (Toray silicone SH200, 5cs), and the mixture was dispersed and mixed for 12 hours in a ball mill.
  • the initial viscosity of the fluid thus obtained was 0.2 poise, and when an electric field of 2 kv/mm was applied, the viscosity increased to 11 poise (162 sec ⁇ 1).
  • Spherical silica particles as used in Example 1 were preliminarily heated at 250°C for 16 hours to adquately remove NH3, water and ethanol. Then, 10.0 g of the silica particles thus obtained were added to 18.7 g of silicone oil (Toray silicone SH200, 10cs), and the mixture was dispersed and mixed for 12 hours in a ball mill. The electroviscous effect was measured with respect to the fluid thus obtained, whereby no increase in the viscosity was observed.
  • silicone oil Toray silicone SH200, 10cs
  • Spherical silica particles as used in Example 1 were preliminarily heated at 250°C for 16 hours to adquately remove NH3, water and ethanol.
  • 10.0 g of silica particles thus obtained 10.0 g of distilled water was added, followed by vacuum drying to obtain particles having a water content of 6.8%.
  • 10.0 g of the particles were added to 18.7 g of silicone oil (Toray silicone SH200, 10cs), and the mixture was dispersed and mixed for 12 hours in a ball mill. The electroviscous effect was measured with respect to the fluid thus obtained, whereby no increase in the viscosity was observed.
  • silicone oil Toray silicone SH200, 10cs
  • Pulverized silica gel was used instead of spherical silica particles in Example 3, and the electroviscous effect was measured, whereby discharge took place when an electric field of 0.5 kv/mm was applied, and subsequent measurement could not be conducted.
  • the present invention provides an electroviscous fluid having high stability as compared with the compositions disclosed in the prior art.

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  • Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Inorganic Chemistry (AREA)
  • Lubricants (AREA)
  • Compositions Of Macromolecular Compounds (AREA)
EP89108600A 1988-05-13 1989-05-12 Elektroviskose Flüssigkeiten Expired - Lifetime EP0341737B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP116631/88 1988-05-13
JP11663188 1988-05-13

Publications (2)

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EP0341737A1 true EP0341737A1 (de) 1989-11-15
EP0341737B1 EP0341737B1 (de) 1992-01-02

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EP89108600A Expired - Lifetime EP0341737B1 (de) 1988-05-13 1989-05-12 Elektroviskose Flüssigkeiten

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EP (1) EP0341737B1 (de)
JP (1) JP3061058B2 (de)
KR (1) KR0134091B1 (de)
AU (1) AU612483B2 (de)
DE (1) DE68900630D1 (de)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0509574A1 (de) * 1991-04-15 1992-10-21 General Motors Corporation Elektrorheologische Flüssigkeiten und Verfahren zu deren Herstellung und deren Verwendung
EP0727478A2 (de) * 1995-02-14 1996-08-21 Toyota Jidosha Kabushiki Kaisha Dilatante Zusammensetzung
DE102011018177A1 (de) 2011-04-19 2012-10-25 Raino Petricevic Paste und deren Verwendung

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3047507A (en) * 1960-04-04 1962-07-31 Wefco Inc Field responsive force transmitting compositions

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3047507A (en) * 1960-04-04 1962-07-31 Wefco Inc Field responsive force transmitting compositions

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0509574A1 (de) * 1991-04-15 1992-10-21 General Motors Corporation Elektrorheologische Flüssigkeiten und Verfahren zu deren Herstellung und deren Verwendung
EP0727478A2 (de) * 1995-02-14 1996-08-21 Toyota Jidosha Kabushiki Kaisha Dilatante Zusammensetzung
EP0727478A3 (de) * 1995-02-14 1997-06-25 Toyota Motor Co Ltd Dilatante Zusammensetzung
US5843335A (en) * 1995-02-14 1998-12-01 Toyota Jidosha Kabushiki Kaisha Dilatancy liquid
DE102011018177A1 (de) 2011-04-19 2012-10-25 Raino Petricevic Paste und deren Verwendung

Also Published As

Publication number Publication date
KR0134091B1 (ko) 1998-05-15
JP3061058B2 (ja) 2000-07-10
DE68900630D1 (de) 1992-02-13
KR900019063A (ko) 1990-12-22
JPH02209997A (ja) 1990-08-21
EP0341737B1 (de) 1992-01-02
AU3405489A (en) 1989-11-16
AU612483B2 (en) 1991-07-11

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