JPH09279174A - Electroviscous fluid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an electroviscous fluid exhibiting excellent electroviscous effect even with a small amount of dispersed particles, causing little contamination of system and useful for a crusher, etc., by dispersion particles of an N- acylated polyaniline in an electrically insulating liquid. SOLUTION: An electroviscous fluid is produced by dispersing an N-acylated polyaniline in an electrically insulating liquid such as mineral oil or synthetic oil and preferably compounding the dispersion with one or more electroviscosity- improving agents selected from amine compounds, amide compounds, imide compounds and sulfonic acid salts. The N-acylated polyaniline preferably has a number-average molecular weight of 10,000-100,000 and an average particle diameter of 0.1-150μm.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an electrorheological fluid, and more particularly to an electrorheological fluid whose viscosity can be controlled by applying a voltage.

[0002]

2. Description of the Related Art The phenomenon in which the apparent viscosity of a fluid changes when a voltage is applied to a fluid in which some kind of solid particles are dispersed as dispersed particles in an electrically insulating liquid (dispersion medium) is called the Winslow effect. That is, the fluid that exhibits such an effect is an electrorheological fluid. Since the Winslow effect has a fast response speed and gives a large change in viscosity with a small amount of electric power, application of this electrorheological fluid to, for example, clutches, dampers, brakes, shock absorbers, suspensions and the like is under study.

The conventional electrorheological fluid is obtained by dispersing solid particles of cellulose, starch, silica gel, ion exchange resin, lithium polyacrylate, etc. as dispersed particles in silicone oil, kerosene, chlorinated paraffin, etc. as a dispersion medium. It has been known. These electrorheological fluids are
Satisfactory results were not obtained because of problems such as low stress when voltage was applied and poor stability.

In order to solve this problem, various dispersed particles have been studied. EP (public) 039
No. 4005 and JP-A-3-139598,
An electrorheological fluid using polyaniline as dispersed particles is disclosed. Since this polyaniline is chemically stable, has a low specific gravity, and its conductivity can be easily controlled, it is a very promising material as dispersed particles of an electrorheological fluid. However, since these polyanilines obtained by oxidative polymerization are treated with an alkali and used, the particles in this state do not have a sufficient electroviscous effect. Further, since the solid particles are black, the electrorheological fluid in which the solid particles are dispersed becomes completely black, and the system using the electrorheological fluid is highly contaminated. Therefore, there are problems such as labor required for cleaning the system and difficulty in confirming the liquid level, which is not preferable.

[0005]

SUMMARY OF THE INVENTION The present invention has been made from the above point of view, and provides an electrorheological fluid having an excellent electrorheological effect even with a small amount of dispersed particles and having less system contamination. It is intended.

[0006]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that the use of N-acylated polyaniline as dispersed particles can effectively achieve the above object of the present invention. The present invention has been completed. That is, the present invention is an electrorheological fluid comprising N-acylated polyaniline particles dispersed in an electrically insulating liquid. Further, in the present invention, N-acylated polyaniline is dispersed in an electrically insulating liquid, and at least one electroviscosity improver selected from amine compounds, amide compounds, imide compounds and sulfonates is blended. This is an electrorheological fluid.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. First, in the present invention, a liquid having electrical insulation is used as the dispersion medium. Such liquids include, for example, mineral oils, synthetic oils or mixtures thereof.

There is no particular limitation on the types of these mineral oils and synthetic oils, and other restrictions, but normally the kinematic viscosity at 40 ° C.
Those in the range of 5 to 300 mm ² / s are preferably used. Here, examples of the mineral oil include paraffin-based mineral oil, intermediate-based mineral oil, and naphthene-based mineral oil. Examples of synthetic oils include alicyclic hydrocarbons, condensed alicyclic hydrocarbons, bridgehead alicyclic hydrocarbons, polybutene, polyolefin [α-olefin (co) polymer], various esters (for example, polyol Ester, dibasic acid ester, phosphoric acid ester, etc.), various ethers (eg, polyvinyl ether, polyphenyl ether, etc.), silicone oil, alkylbenzene, alkylnaphthalene, and the like. Among these, polybutene, alkylbenzene and Alkylnaphthalene is preferable from the viewpoint of the performance of the obtained electrorheological fluid.

Next, N-acylated polyaniline is used as the dispersed particles. The N-acylated polyaniline can be obtained by subjecting polyaniline to N-acylation according to a conventional method. The raw material polyaniline is an electrolytic polymerization method in which aniline is electrolytically oxidized on an anode made of platinum, gold, carbon, stainless steel, etc. in an acidic solution (electrolytic oxidation polymerization method), and aniline is oxidized in an acidic solution such as ferric chloride. Those obtained by any of the production methods of the catalyst polymerization method (chemical oxidative polymerization method) with the agent are preferably used.

Here, when polyaniline is obtained by the electrolytic oxidation polymerization method, the concentration of aniline is 0.05 to 2 mol / liter and the acid concentration is 0. 2 in an acidic aqueous solution of hydrochloric acid, sulfuric acid, borofluoric acid, perchloric acid or the like. 1 to 4 mol / liter, liquid temperature-
The aniline is polymerized at 10-30 ° C. The polymerization method may be a constant potential method, a cyclic method or a pulse method. Further, when polyaniline is obtained by the chemical oxidative polymerization method, 0.01 to 5 mol / liter of an oxidizing agent aqueous solution is added to the same polymerization solution as that used in the electrolytic oxidative polymerization method while vigorously stirring. As an oxidizer, the standard potential of ferric chloride, ammonium persulfate, potassium iodate, etc. when made into an aqueous solution is 0.8 to 1.2 V relative to the standard hydrogen electrode.
Is preferably used.

The polyaniline thus obtained is
As shown in the following formula (1), it is an emeraldine salt, and the emeraldine base of the following formula (2) is made with ammonia or the like. When emeraldine base is reduced with phenylhydrazine or the like, it becomes leucoemeraldine of the following formula (3).

[0012]

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Leucoemeraldine is N-acylated with reference to the N-acylation of aniline as shown below to obtain the following formula (4):

[0014]

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[In the formula, R represents an alkyl group having 1 to 50 carbon atoms or an alkylphenyl group, an alkylene group having 2 to 50 carbon atoms or an alkylenephenyl group, and preferably an alkyl group having 1 to 20 carbon atoms or an alkylene group. Is. n is 1
Is an integer of 5,000, m is an integer of 19 to 5,000, and n / (n + m) = 0.1 to 0.8, preferably 0.2 to 0.5. ] N-acylated polyaniline represented by these can be obtained.

The N-acylated polyaniline of the formula (4) is not limited to block copolymers, but widely includes random copolymers, alternating copolymers and the like. The N-acylated polyaniline produced has a number average molecular weight of usually 2,000 to 500,000, preferably 10,000.
１００100,000. There are the following three methods for N-acylation of aniline. (1) Acylation with carboxylic acid Aniline and carboxylic acid are reacted in the presence of excess aniline or in pyridine in the presence of silicon tetrachloride or the like as a dehydrating agent. (2) Acylation with acid halide Aniline and acid halide are reacted in the presence of aniline in the excess or in the presence of a tertiary amine in a solvent such as ether.
Alternatively, the reaction is carried out in pyridine. (3) Acylation with acid anhydride Aniline and acid anhydride are reacted without solvent or in an inert solvent such as ether or benzene. At this time, it is effective to add a small amount of pyridine or sulfuric acid to accelerate the acylation reaction.

When the produced N-acylated polyaniline is used as the dispersoid, its average particle size is not particularly limited and may be appropriately selected according to various situations.
Generally, it is preferably in the range of 0.1 to 150 μm. If the average particle diameter is less than 0.1 μm, a lot of energy is required for pulverization, and the cost tends to be high.
Those having a thickness of more than 0 μm are prone to sedimentation, which may impair the storage stability.

The method for pulverizing the N-acylated polyaniline is not particularly limited, but it can be easily pulverized by an ordinary mechanical method. It is possible to obtain a stable electrorheological effect by using the crushed particles after drying as much as possible. The N-acylated polyaniline is adsorbed on the surface of inorganic or polymer solid particles (silica, alumina, diatomaceous earth, cellulose, natural protein, ion-exchange resin, zeolite, etc.) by a known method to form a dispersion medium. It may be dispersed.

In the present invention, at least one electroviscosity improver selected from amine compounds, amide compounds, imide compounds and sulfonates may be blended, if desired, for the purpose of further enhancing the electroviscous effect. it can. These compounds are known as detergents and dispersants for lubricating oils, and when added to an electrorheological fluid, their storage stability can be improved and the electrorheological effect can be significantly improved. .

Examples of the above-mentioned amine compound include benzylamine derivatives and polyalkenylamines. Here, as the benzylamine derivative, for example, a polyolefin having 2 to 8 carbon atoms, preferably an average molecular weight of 5
Polyethylene, polypropylene, polybutylene, etc. in the range of 0 to 5000, phenol, formaldehyde and NH ₂ (R ¹ NH) _p H (where R ¹ is an alkylene group having 2 to 4 carbon atoms, and p is an integer of 1 to 10). Is shown.)
Those obtained by the Mannich reaction with the polyamine represented by are preferably used. As the polyalkenylamine, those obtained by chlorinating the above polyolefin and reacting this with a polyamine represented by NH ₂ (R ¹ NH) _p H (R ¹ and p are the same as above) are obtained. It is preferably used.

Next, as the amide compound, for example, a fatty acid having 6 to 50 carbon atoms, preferably 12 to 30 carbon atoms, and NH ₂
(R ¹ NH) _pH (R ¹ and p are the same as above.)
Fatty acid amides obtained by reacting with a polyamine represented by are preferable. Further, as the imide compound,
For example, polyalkenyl succinic anhydride, which is a reaction product of the above-mentioned polyolefin and maleic anhydride, and NH ₂ (R ¹
A succinimide derivative obtained by reacting with a polyamine represented by NH) _pH (R ¹ and p are the same as above) is preferable. In the above reaction, polyalkenyl succinic acid monoimides or polyalkenyl succinic acid bisimides or a mixture thereof can be obtained by changing the molar ratio of polyalkenyl succinic anhydride and polyamine.

On the other hand, examples of the sulfonate include an oil-soluble alkali metal salt (sodium salt, potassium salt, etc.) or alkaline earth metal salt (calcium salt) of oil-soluble sulfonic acid derived from mineral oil, alkylbenzene, polyolefin and the like. , Magnesium salt, etc.) are preferably used.
These electroviscosity improvers may be used alone or in combination of two or more.

The mixing ratio of each component in the electrorheological fluid of the present invention is not particularly limited and may be appropriately selected according to various situations. For example, 50 to 99% by weight of an electrically insulating liquid and 1 to 5 of N-acyl polyaniline are used.
0% by weight, and if necessary, 0.1% of an electric viscosity improver.
The electrorheological fluid of the present invention can be prepared by blending in a proportion of ˜20% by weight and dispersing. If the content of N-acylated polyaniline is less than 1% by weight, the electrorheological effect may not be exhibited, and if it exceeds 50% by weight, the viscosity at the time of no charge may increase and the fluid may not function as a fluid. It is not preferable due to its limited use. On the other hand, if the amount of the electroviscosity improver is less than 0.1% by weight, the effect of improving the storage stability and the electroviscous effect is not sufficiently exhibited, and if it exceeds 20% by weight, other physical properties of the electroviscous fluid are not exhibited. May be damaged. From the standpoint of balance of viscosity without charge, electrorheological effect, storage stability, and other physical properties, a liquid having an electrical insulating property is used.
.About.98% by weight, N-acylated polyaniline in an amount of 2 to 40% by weight and, if necessary, an electroviscosity improver in an amount of 0.2 to 5% by weight are advantageous.

In the electrorheological fluid of the present invention, in addition to the above-mentioned components, if necessary, a lubricating oil additive such as an antioxidant, an antiwear agent, or an antifoaming agent may be added. it can.

[0025]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the invention thereto. [Example 1] 0.18 mol of aniline hydrochloride was added at 1 mol / mol.
In addition to 180 ml of hydrochloric acid solution, 0.1 ml of ammonium persulfate, which is a chemical oxidative polymerization agent for aniline.
8 mol was added and the reaction was carried out for 3 hours while keeping the reaction temperature at 0 ° C.

After the reaction was completed, the resulting polyaniline 18.
The polyaniline was deprotonated by dispersing 0 g in 120 ml of a 14% by weight aqueous ammonia solution and stirring for 3 hours. After completion of the reaction, the obtained powder was separated by filtration, washed with distilled water and vacuum dried at 80 ° C. to obtain black deprotonated polyaniline (emeraldine base).
Next, 10 g of deprotonated polyaniline was added to 185 ml of a diethyl ether solution containing 30% by weight of phenylhydrazine and reduced at room temperature for 2 hours to obtain 22.5 g of leuco emeraldine. After completion of the reaction, it was washed with methanol and diethyl ether, and dried in vacuum at 80 ° C. 22.5 g of the obtained leuco emeraldine was dissolved in 675 ml of N-methylpyrrolidone to give triethylamine 1
7.55 ml was added. Then, 21.05 ml of n-octanoyl chloride was added dropwise, and the mixture was stirred for 6 hours for acylation. After the reaction was completed, this solution was poured into a 1N aqueous hydrochloric acid solution to precipitate a pale green N-acylated polyaniline. Then, it wash | cleaned with water and methanol and vacuum-dried at 80 degreeC. The number average molecular weight of the obtained N-acylated polyaniline was 70,000. N-
Acylated polyaniline is ground in a mortar and the average particle size is 50μ.
10% by weight of the powder of m was dispersed in 90% by weight of silicone oil to obtain an electrorheological fluid.

Next, using a two-cylinder type rotational viscometer, the viscosity obtained under the conditions of a sample temperature of 40 ° C. and a shear rate of _{500 sec} ⁻¹ was E 0 _KV, and 3 electrodes were _placed between the electrodes at the same temperature and the same shear rate.
The viscosity at the time of applying a voltage of KV / mm and E _{3 KV,} representing the electrorheological effect in E _3KV -E _0KV (Pa). Table 1 shows the results.

Example 2 The N-acylated polyaniline produced in Example 1 was crushed in a mortar and 10% by weight of powder having an average particle size of 50 μm and 0.5% by weight of polybutenylsuccinimide were added at 40 ° C. An electrorheological fluid was obtained by dispersing 89.5% by weight of mineral oil having a viscosity index of 105 at 31 mm ² / s, and the electrorheological effect was measured by the same method as in Example 1. Table 1 shows the results.

Comparative Example 1 The deprotonated polyaniline (emeraldine base) obtained as an intermediate in Example 1 was ground in a mortar and 10% by weight of powder having an average particle size of 50 μm was dispersed in 90% by weight of silicone oil. An electrorheological fluid was obtained and the electrorheological effect was measured in the same manner as in Example 1. Table 1 shows the results.

[0030]

[Table 1]

It can be seen from Table 1 that the electrorheological fluid of the present invention has a higher electrorheological effect than the conventional polyaniline.

[0032]

According to the present invention, the use of N-acylated polyaniline as the dispersoid makes it possible to obtain an electrorheological fluid exhibiting an excellent electrorheological effect and having little system contamination. Therefore, according to the present invention, an electrorheological fluid exhibiting an excellent electrorheological effect can be easily provided by using a general crushing device or a mixing device.

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Claims (2)

[Claims] 1. An electrorheological fluid comprising N-acylated polyaniline particles dispersed in an electrically insulating liquid. 2. An N-acylated polyaniline is dispersed in an electrically insulating liquid, and at least one electroviscosity improver selected from an amine compound, an amide compound, an imide compound and a sulfonate is added. An electrorheological fluid characterized by.