JP2799606B2 - Electrorheological fluid - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an electrorheological (Electro-Rheological) device whose voltage-controllable viscoelastic properties can be largely and reversibly changed.
Rheological) It relates to fluids and is used for electrical control of mechanical devices such as engine mounts, shock absorbers, valves, actuators, and clutches.

[Prior Art] The phenomenon in which the apparent viscosity is greatly changed by the application of an electric field has been long known as the Winslow effect. The initial fluids consisted of starch or starch dispersed in mineral oil or lubricating oil, which was sufficient to recognize the importance of the electrorheological effect but lacked reproducibility.

In order to obtain a fluid having a high electrorheological effect and good reproducibility, many proposals have been made mainly on fine powders. For example, fine particles of a highly water-absorbent resin having an acid group such as polyacrylic acid (JP-A-53-93186), ion-exchange resin (JP-B-60-3)
1211) and alumina silicate (JP-A-62-95397).

Each of these electrorheological fluids is made by impregnating a hydrophilic solid fine powder with water and dispersing it in an insulating oily medium. When a high voltage is applied from the outside, the action of water causes polarization of the fine powder. . It is said that the polarization increases crosslinks between the particles in the electric field direction, thereby increasing the viscosity.

Since the electrorheological effect differs depending on the combination of the powder and the oily medium used, a combination that exhibits a higher viscosity change when a voltage is applied has been proposed. In addition to such a combination of a powder and an oily medium, JP-A-62-95397 discloses the addition of a third component other than a powder containing insulating oil and water for the purpose of preventing or dispersing the powder. Investigations have been made, and recently, an invention in which a third component is added for the purpose of increasing the electrorheological effect as proposed in US Pat. No. 3,427,247 has been proposed.

In recent years, non-aqueous non-aqueous electrorheological fluids using ferroelectric substances and semiconductor particles have been proposed. For example, a fluid using organic semiconductor fine particles such as polyacenequinone (Japanese Patent Application Laid-Open No. 61-216202), and a dielectric fine particle in which a conductive thin film layer is formed on the surface of organic solid particles and further an electrically insulating thin film layer is formed ( 63-97694). Non-aqueous electrorheological fluids are greatly expected to overcome various deficiencies caused by the presence of conventional water, and much research has been conducted. The present inventors have also conducted research in this direction,
It has been discovered that carbon fine powder having optical anisotropy exhibits an excellent electrorheological effect (Japanese Patent Application No. 63-212615). However, in the prior art relating to non-aqueous electrorheological fluids,
There is no disclosure of the existence of a third component for stabilizing or improving the performance of the electrorheological fluid as found in a water-based electrorheological fluid.

[Problems to be Solved by the Invention] As described above, with respect to these aqueous electrorheological fluids or nonaqueous electrorheological fluids, there are few methods for greatly improving the viscosity change when a high voltage is applied. No examples are found for some non-aqueous electrorheological fluids.
Regarding aqueous systems, US Pat. No. 3,427,247 has attempted to enhance the electrorheological effect by adding amines, acids, etc. as additives.
However, although an increase in the electrorheological effect was achieved as compared with the case where no additive was added, the current value was greatly increased.

The present invention overcomes the drawbacks of conventional additives used for aqueous electro-rheological fluids, such as increasing the current value when trying to enhance the electro-rheological effect, and provides an additive that is also effective for non-aqueous systems. It is an object of the present invention to provide an electrorheological fluid, which has not been known in the art, and in which the electrorheological effect is stably increased.

[Means for Solving the Problems] The present inventors have intensively studied an organic compound, an inorganic compound, or a composite material thereof having a high insulating property, which can be added to an electrorheological fluid, and reached the present invention.

That is, a low-polarity compound is generally used for the insulating oil used for the electrorheological fluid in order to satisfy the required electric characteristics. For example, mineral oils, silicone oils, aromatic oils and the like can be mentioned.
And low. A small amount of a compound having a relative dielectric constant of 4 or more at room temperature, which is a component different from the insulating oil, was added to this insulating oil, and the electrorheological effect was examined. The inventors have found that when added to an electrorheological fluid, the electrorheological effect can be stably increased, and the present invention has been accomplished.

The electrorheological fluid according to the present invention is a silicone oil excellent in electric insulation, a mineral oil composed of a component not containing P = N bonds, a transformer oil composed of a component not containing P = N bonds, a paraffin oil, a halogen fragrance. An electrorheological fluid in which fine carbonaceous powder is dispersed in one of the group oils, to which a compound having a P = N bond is added in an amount of 0.001% by weight or more and 30% by weight or less.

 The details of the present invention are described below.

In order to produce an electrorheological fluid, as an insulating oil (oil medium), silicone oil, mineral oil composed of components not containing P = N bonds, transformer oil composed of components not containing P = N bonds, paraffin oil Although halogenated aromatic oils and the like are used, in the present invention, the effect can be obtained using any insulating oil, and the type is not particularly limited. Among these electric insulating oils, polydimethylsiloxane and polymethylsiloxane are used. It is excellent in that silicone oil such as phenylsiloxane can be used even in a state of being in direct contact with a rubber-like elastic material.

The viscosity of the electrically insulating oil at 25 ° C. is 0.65 to 1000 centistokes (cSt), preferably 5 to 50 cSt. 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 increases, and the change in viscosity due to the electrorheological effect decreases. In addition, by using a moderately low-viscosity electric insulating oil as a liquid phase, the dispersed phase can be efficiently suspended.

Further description of a suitable fine carbonaceous powder as the dispersed phase of the electrorheological fluid of the present invention is preferably a carbon content of 80 to 97% by weight, particularly preferably 90 to 95% by weight. The C / H ratio (carbon / hydrogen atom ratio) of the carbonaceous fine powder is
Those having 1.2 to 5 are preferred, and those having 2 to 4 are particularly preferred.

Specifically showing the carbonaceous fine powder having the C / H ratio,
Coal tar pitch, petroleum pitch, finely crushed pitch obtained by pyrolyzing polyvinyl chloride, etc., fine powder consisting of various mesophases obtained by heat treatment of those pitch or tar components, that is, formed by heating Optically anisotropic microspheres (spherulites or mesophase microspheres)
Powder obtained by dissolving the pitch component in a solvent and fractionating it, further pulverized, and the pitch raw material is subjected to heat treatment to form a bulk mesophase (for example,
-30887), so-called low-temperature-treated carbon fine powder, such as finely pulverized powder, finely ground partially crystallized pitch, and carbonized thermosetting resin such as phenolic resin at low temperature. Examples further include coals such as anthracite and bituminous coal and finely pulverized heat-treated products thereof, hydrocarbon-based polymers such as polyethylene, polypropylene or polystyrene and chlorine-containing polymers such as polyvinyl chloride or polyvinylidene chloride. And carbon spheres obtained by heating the mixture under pressure, or carbon spheres obtained by pulverizing the same, or those obtained by pulverizing the same.

The proportion of the dispersed phase and the liquid phase constituting the electrorheological liquid of the present invention is such that the content of the dispersed phase is 1 to 60% by weight, preferably 10 to 50% by weight.
% By weight, and the content of the liquid phase comprising the electric insulating oil is
It is 99 to 40% by weight, preferably 90 to 50% by weight. If the amount of the dispersed phase is less than 1% by weight, the electrorheological effect is small, and if it exceeds 60% by weight, the initial viscosity in the absence of an electric field is significantly increased.

Preferred particle size for the dispersed phase is 0.01-100 microns,
Preferably 0.1-20 microns, more preferably 0.5-5
In the micron range. If it is less than 0.01 micron, the initial viscosity becomes remarkably large in the absence of an electric field, and the change in viscosity due to the electrorheological effect is small. If it exceeds 100 microns, sufficient stability as a liquid dispersed phase cannot be obtained.

The compound containing a P = N bond used in the present invention is a group of compounds generally called phosphazene,
Broadly speaking, the following three types of structures are known.

Compounds having at least three units of P = N bonds in the molecule and having a cyclic structure Compounds having a cyclic structure in which P = N bonds are repeated continuously Compounds having a three-dimensional network structure by P = N bonds Examples of compounds belonging to the group include (PN
_{F 2) 3, (PNF 2} ) 4, (PNF 2) n [n <14] trimers side groups of F atoms, such as, tetramer compound of the n-mer, (PNCl _{2) 3,} (PNCl ₂ ) ₄ , (PNCl ₂ ) _n [n <14], etc., a compound in which a side chain group is a trimer, tetramer or n-mer of a Cl atom,
(PNBr ₂ ) ₃ , (PNBr ₂ ) ₄ , (PNBr ₂ ) _n [n <14], etc., where the side-chain group is a Br atom trimer, tetramer, n-mer compound,
(PNI ₂ ) ₃ , (PNI ₂ ) ₄ , (PNI ₂ ) _n [n <14], etc., where the side chain group is a trimer, tetramer, or n-mer compound of an I atom, or a halogen thereof. Compounds in which some or all of the side chain groups of a compound having an atom in the side chain are substituted with an organic compound can be given.

Compounds having this organic compound in the side chain include trimer, tetramer and n-mer compounds containing halogen atoms, for example, CF ₃ CH ₂
It can be obtained by substitution with a nucleophile such as ONa or C ₆ H ₅ ONa. However, no matter what method or means is taken as the synthesis method, the same effect can be obtained as long as the compound has a cyclic structure having at least 3 units of P = N bonds in the molecule.

However, preferably, these cyclic compounds have a side chain group of CF ₃ C
_{H 2 O-, CF 3 CF 2} CH 2 O- or a halogen laden aliphatic alkoxy _{groups, C 6 H 5 O-, RC} 6 H 4 O- (R: aliphatic hydrocarbons, halogenated aromatic hydrocarbons Various phenoxy groups such as hydrogen), CF ₃ C
_{H 2 NH-, CF 3 CF 2} CH 2 NH- , etc. inclusive aliphatic amino group _{halogen, C 6 H 5 NH-, RC} 6 H 4 NH- (R: aliphatic hydrocarbons, halogenated aromatic hydrocarbons Compounds substituted with various aromatic amino groups such as hydrogen) are desirable in view of durability and the like.

Examples of compounds belonging to the compound group of (PN)
F ₂ ) _n [n> 13], (PNCl ₂ ) _n [n> 13], (PNBr ₂ )
_n [n> 13], (PNI ₂ ) _n [n> 13] and other side chain groups are halogen atoms and the main chain is composed of P = N. A polymer in which the main chain in which part or all of the side chain groups are substituted with an organic compound and P = N can be given.

The polymer having the organic compound in the side chain can be obtained by substituting a polymer containing a halogen atom with a nucleophilic reagent such as CF ₃ CH ₂ ONa or C ₆ H ₅ ONa. However, no matter what method or means is taken as the synthesis method, the same effect can be obtained as long as the structure of the polymer has a chain structure having a P = N bond in the main chain.

However, preferably, these chain polymers have CF ₃ C
_{H 2 O-, CF 3 CF 2} CH 2 O- or a halogen laden aliphatic alkoxy _{groups, C 6 H 5 O-, RC} 6 H 4 O- (R: aliphatic hydrocarbons, halogenated aromatic hydrocarbons Various phenoxy groups such as hydrogen), CF ₃ C
_{H 2 NH-, CF 3 CF 2} CH 2 NH- , etc. inclusive aliphatic amino group _{halogen, C 6 H 5 NH-, RC} 6 H 4 NH- (R: aliphatic hydrocarbons, halogenated aromatic hydrocarbons Compounds substituted with various aromatic amino groups such as hydrogen) are preferably selected in consideration of durability and the like.

Are generally insoluble and solid in various solvents obtained in the process of synthesizing the compounds containing P = N or in the process of synthesizing the phosphorus nitride compound. Although it depends on the synthesis process, P and N are the main components as elements, and the others are some of the elements contained in the synthesis raw material.

0.001% by weight or more, preferably 0.1% by weight or more and 30% by weight or less, more preferably 0.1% by weight or more,
An electrorheological fluid is manufactured by adding 0.03% by weight or more and 10% by weight or less. Various methods are conceivable as the adding method, such as a method of adding at the time of manufacturing an electrorheological fluid, a method of adding after manufacturing an electrorheological fluid, and a method of adding a powder after microencapsulation with a phosphazene derivative. The present invention can obtain the effect by adopting any of these methods, and the addition method according to the following examples does not limit the present invention at all.

Additives such as a surfactant and a dispersant can be added to the electrorheological liquid of the present invention as long as the effects of the present invention are not impaired.

Example 1 As a non-aqueous powder, a carbonaceous powder having an average particle diameter of 3 μm (carbon content 93.78) produced by heat-treating mesophase carbon from coal tar pitch in a nitrogen stream.
A fluid was produced by dispersing 100 g of a silicone oil (TSF451-10, manufactured by Toshiba Silicone Co., Ltd.) in an amount of 100 g (weight%, C / H ratio 2.35, moisture 0.2 weight%). 100 g of this fluid (PN (OC
₆ H _{5) 2) 3} was used as electro-rheological fluids were mixed 30 minutes in a mortar was added 0.35 g.

Example 2 3.32 g of (PN (OC ₆ H ₅ ) ₂ ) ₃ as an additive was added to 100 g of a fluid in which the carbonaceous powder was dispersed in silicone oil, and an electrorheological fluid was added in the same manner as in Example 1. Created.

Example 3 As an additive, (PN (OCH ₂ CF ₃ ) ₂ ) ₃ was added in an amount of 0.6 g to 100 g of a fluid in which the carbonaceous powder was dispersed in silicone oil, and an electrorheological fluid was added in the same manner as in Example 1. Created.

[Comparative Example 1] Example _{(PN (OC 6 H 5)} 2) in 1 ₃ and Comparative Example 1 A sample of additive-free.

The electrorheological effect of each of the electrorheological fluids obtained in Examples 1 to 3 and Comparative Example 1 was measured. The electro-rheological effect was measured between the inner and outer cylinders using a double cylinder rotational viscometer.
The change in viscosity when a voltage of 2 KV / mm was applied was shown.

As is clear from the results, the addition effect of the phosphazene derivative is clear because the viscosity at the time of voltage application is increased by adding a small amount of the phosphazene derivative.

[Effect of the Invention] An electrorheological fluid having an increased electrorheological effect without increasing the current value can be obtained.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-2-196892 (JP, A) JP-A-2-202594 (JP, A) JP-A-3-139599 (JP, A) (58) Field (Int.Cl. ⁶ , DB name) C10M 137/16 C10N 40:14

Claims (1)

(57) [Claims] 1. A silicone oil having excellent electrical insulation properties, P = N
In an electrorheological fluid in which a carbonaceous fine powder is dispersed in any one of a mineral oil composed of a component not containing a bond, a transformer oil composed of a component containing no P = N bond, a paraffin oil, and a halogen aromatic oil, An electrorheological fluid in which a compound containing a P = N bond is added in an amount of 0.001 to 30% by weight.