JPH047397A - Electroviscous fluid - Google Patents

Abstract

PURPOSE:To obtain an electroviscous fluid generating a large shear stress by applying a weak electric field and having a small current density applied and excellent electric current characteristics by incorporating a dispersing phase consisting of an org. polymer particle with cation exchange capacity, a dispersing medium consisting of a specified insulating liq. and a specified polymer additive. CONSTITUTION:An electroviscous fluid is obtd. by incorporating a dispersing phase consisting of an org. polymer particle with cation exchange capacity (e.g. a sulfonic acid group-contg. PS polymer), a dispersing medium consisting of an insulating liq. wherein a hydrocarbon compd. is a main ingredient and a polymer additive. The polymer additive is constituted of structural units (A) of formula I (wherein R is H or CH; X is a group of formula II, III or IV, or CN) and structural units (B) of formula V (wherein R is H or CH3; Y is an arom. hydrocarbon group) as essential constituting units and a polymer wherein the compsn. is in the range of 0.1-60wt.% structural units A and 40-99.9wt.% structural units B and the average mol.wt. is 1,000-10,000,000. This fluid has excellent electric current characteristics wherein it generates a large shear stress by applying a relatively weak electric field and a current density applied at that time is small and the generated shear stress and the current density are excellently stable for long time.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to electrorheological fluids. More specifically, it has excellent current characteristics in that it generates a large shear path force even when a relatively weak electric field is applied, and the current density that flows at that time is small, and the stability of the shear path force and current density over time without being generated. The electrorheological fluid has excellent dispersion stability (the ability to maintain the electrorheological fluid in a uniform state for a long time without causing the dispersed phase to settle or float) when no electric field is applied. It is something.

<Prior art> An electrorheological fluid is a fluid obtained by dispersing or suspending solid particles in an insulating dispersion medium, and its rheological or flow properties can be changed to a viscoplastic type by applying an electric field change. It is generally known as a fluid that exhibits the so-called Winslow effect, in which the viscosity increases significantly and a large shear path force is induced when an external electric field is applied.

Since the Winslow effect is characterized by quick response, attempts have been made to apply electrorheological fluids to clutches, dampers, brakes, shock absorbers, actuators, pulp, and the like.

Conventionally, known electrorheological fluids include solid particles such as cellulose, starch, soybean casein, and silica gel dispersed in insulating oil such as silicone oil, diphenyl chloride, and transformer oil. However, those using cellulose, starch, soybean casein, silica gel, etc.
There was a problem in that the shear road force generated was small.

On the other hand, as an electrorheological fluid that generates high shear path force,
For example, powder of ion exchange resin is suspended in higher alkyl ester of aromatic carboxylic acid (JP-A-50-92
278>, and a composition comprising a crystalline substance, a dielectric liquid, and an additive that conducts current along only one of the three crystal axes (Japanese Patent Laid-Open No. 1-170693). However, in these electrorheological fluids, the current density flowing when an electric field is applied is relatively large and the current characteristics are poor, and the dispersed phase easily separates when no electric field is applied, and conversely, the dispersed phase is When the concentration is increased, there is a problem in that fluidity becomes poor.

In order to solve the problems of separation of dispersed phases and fluidity, methods of adding additives such as dispersion stabilizers to electrorheological fluids have been proposed. However, many of the surfactants and stearic acid additives known as normal dispersion stabilizers have poor solubility in dispersion media consisting of insulating liquids mainly composed of hydrocarbon compounds. , could not be substantially added to these systems. Also, even if it is dissolved in a dispersion medium (such as ricinoleic acid or oleic acid),
It is not possible to increase the dispersion stability so much that it does not pose a practical problem.

In addition, in an electrorheological fluid having silica gel as a dispersed phase, a polymer of an N- and/or OH-containing compound and an alkyl group-containing compound having 4 to 24 carbon atoms such as higher alkyl (meth)acrylate is used as a dispersion stabilizer. Showa 6l-259
752) and modified silicone oil (JP-A-2-2663)
3> has been proposed.

However, although such dispersion stabilizers are effective for electrorheological fluids containing silica gel as the dispersed phase,
These methods have not been sufficient to improve the dispersion stability of electrorheological fluids containing polymers such as sulfonic acid group-containing polystyrene ion exchange resins as the dispersed phase. Moreover, the electrorheological fluids described in these publications had the problem that the shear path force generated was insufficient.

(Problems to be Solved by the Invention) The present invention solves the above-described problems that conventional electrorheological fluids have.

Therefore, an object of the present invention is to generate a large shear stress even by applying a relatively weak electric field, to have excellent current characteristics such that the current density flowing at that time is small, and to maintain the shear stress and current density over time without being generated. Excellent stability,
Furthermore, it is an object of the present invention to provide an electrorheological fluid that has a low viscosity when no electric field is applied, has excellent fluidity, and has particularly excellent dispersion stability in that the dispersed phase is difficult to settle or float.

(Means and effects for solving the problem) The present invention provides a dispersed phase consisting of organic polymer particles having cation exchange ability, a dispersed phase consisting of an insulating liquid mainly composed of a hydrocarbon compound, and a polymer additive. It is an electrorheological fluid containing a structural unit represented by a polymer (in the formula, R1 is hydrogen or a methyl group, and x is or -〇N).
In the formula, R2 is hydrogen or a methyl group, and Y is an aromatic hydrocarbon group. ) as an essential structural unit, and the structural unit (A) is 0.1 to 6
Polymer (I) with an average molecular weight of 1000 to 10 million, which is 0% by weight and the structural unit (B) is in the range of 40 to 99.9% by weight.
This relates to an electrorheological fluid made using .

The polymer (I) that is effective as a polymer additive contained in the electrorheological fluid of the present invention has the above-mentioned structural unit (A) and structural unit (B) as essential structural units. Content in polymer (I) or structural unit (A) 0.1
-60% by weight and structural unit (B) should be in the range of 40-99.9% by weight. Structural unit (A> or structural unit (
Polymers with a content of B) outside this range are electrorheological fluids that have low viscosity when no electric field is applied and have excellent fluidity and dispersion stability with suppressed separation of the dispersed phase. I can't get it.

The polymer (I) may contain structural units other than the structural unit (A) and the structural unit (B) (hereinafter referred to as the structural unit (C)), but the structural unit (A) and the structural unit Unit (B)
It is preferable that the total content of all the constituent units is 50% by weight or more. If this total content is less than 50% by weight, the problem that sufficient dispersion stability may not be obtained may occur. be.

The substituent Y in the structural unit (B), which is an essential constituent unit of the polymer (I), must be an aromatic hydrocarbon group, and examples of the aromatic hydrocarbon group include, for example, a phenyl group and a naphthyl group. , methylphenyl group, ethylphenyl group, dimethylphenyl group, trimethylphenyl group, etc.

Polymer (I) effective as a polymer additive in the present invention
The method for obtaining is not particularly limited, and for example, by polymerization, the unsaturated compound (a) that provides the structural unit (A) and the unsaturated compound (b) that provides the structural unit (B) are essential components, and other components are added as necessary. Examples include a method of polymerizing a monomer mixture to which an unsaturated compound (c) is added to give the structural unit (C).

The polymerization method may be according to a conventionally known method, for example, a method of solution polymerizing the monomer mixture in an organic solvent or a method of bulk polymerizing. If an insulating liquid is used, the electrorheological fluid of the present invention can be prepared by mixing the solution of polymer (I) obtained by polymerization with the organic polymer particles constituting the dispersed phase as it is.

In addition, as the polymer (I), the above-mentioned unsaturated compound (
Rantam copolymers obtained using low molecular weight vinyl monomers may be used as a) and (b), and structural units (A
>, t or a low molecular weight vinyl that gives a structural unit (A) or (B) that is not contained in the macromonomer in the presence of a high molecular weight macromonomer containing the structural unit (B) and having a polymerizable functional group at the end. A graft copolymer obtained by polymerizing monomers may also be used.

Examples of the unsaturated compound (a) that provides the structural unit (A) which is an essential constitutional unit of the polymer (I) include 2-vinylpyridine, 4-vinylpyridine, N-vinyl-2-pyrrolidone, and (meth)acrylonitrile. Polymerizable functional groups containing a structural unit (A>) in the molecule, such as macromonomer AN-6 (styrene/acrylonitrile macromonomer manufactured by Toagosei Kagaku Kogyo ■), which has a polymerizable functional group at the end. Examples include macromonomers with high molecular weight, and one or more of these can be used.

Examples of the unsaturated compound (b) that provides the structural unit (B) which is an essential constituent unit of the polymer (I) include aromatic compounds such as styrene, vinylnaphthalene, vinylanthracene, methylstyrene, ethylstyrene, dimethylstyrene, and trimethylstyrene. Group vinyl monomers and macromonomers AS
-6 (styrenic macromonomer manufactured by Toagosei Kagaku Kogyo ■), which contains the structural unit (B) in the molecule and has a polymerizable functional group at the end. One or more of these can be used.

Examples of the unsaturated compound (C) that provides other structural units (C) that may be contained in the polymer (I> if necessary) include ethylene, propylene, butadiene, 2-
Methyl butadiene, vinyl chloride, vinylidene chloride, methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, cetyl ( Meta)
Low molecular weight monomers such as acrylate, pentadecyl (meth)acrylate, stearyl (meth)acrylate, behenyl (meth)acrylate, vinyl acetate, maleic anhydride, and macromonomer AA-6 (methyl methacrylate-based macro manufactured by Toagosei Chemical Industry Co., Ltd.) Examples include macromonomers with a high molecular weight such as (monomer), and one or more types of these can be used.

The organic polymer particles having cation exchange ability constituting the dispersed phase in the electrorheological fluid of the present invention include polymer particles having a functional group that dissociates cations and becomes anions themselves in the presence of a polar solvent such as water. There are no particular limitations as long as the particles are agglomerated particles, and examples thereof include particles of organic polymers having dissociative groups such as sulfonic acid groups, carboxylic acid groups, and phosphoric acid groups in the molecule. Among these, organic polymer particles having sulfonic acid groups are preferable, and particles made of polystyrene polymers containing sulfonic acid groups are particularly preferable because they provide an electrorheological fluid with excellent shear stress and current density.

The types of cations that the organic polymer particles dissociate in the #l solvent are not particularly limited, and include, for example, hydrogen cations; lithium ions, sodium ions, potassium ions, calcium ions, aluminum ions, cuprous ions,
Examples include metal cations such as cupric ions; organic cations such as tetramethylammonium ions and pyridinium ions.

In order to obtain organic polymer particles having cation exchange ability that can be used as a dispersed phase in the present invention, for example, a vinyl compound having an ion dissociative group such as a sulfonic acid group or a carboxylic acid group may be used alone or as necessary. A monomer mixture containing a vinyl monomer may be polymerized by a known method and pulverized to a predetermined particle size if necessary, or an ionic dissociative group such as a sulfonic acid group may be introduced into the polymer by a known method. Alternatively, an ionic dissociative group may be introduced by hydrolyzing a polymer having an ester group or the like by a known method.
Furthermore, a commercially available polystyrene-based ion exchange resin (for example, Amberlite 0 manufactured by Tokyo Organic Chemical Industry Co., Ltd.) pulverized to an appropriate particle size may be used.

In the present invention, the average particle diameter of the organic polymer particles constituting the dispersed phase is preferably in the range of 0.1 to 50 μm. If the average particle diameter of the 8!1 polymer particles is less than 0.1 μm, a large shear stress may not be obtained when an electric field is applied to the prepared electrorheological fluid. Furthermore, if the average particle diameter of the m-polymer particles exceeds 50 μm, it may not be possible to obtain an electrorheological fluid with excellent dispersion stability when no electric field is applied.

The hydrocarbon compound constituting the main component of the dispersion medium in the electrorheological fluid of the present invention is not particularly limited as long as it is an insulating liquid consisting essentially of hydrocarbons, and examples include aliphatic compounds such as dodecane, hexadecane, and octadecane. Hydrocarbons: Aromatic hydrocarbons such as benzene, naphthalene, anthracene, and phenanthrene; Alkyl-substituted aromatic hydrocarbons such as toluene, ethylbenzene, and xylene: THERM-S 030
0゜THERMS @700. THERMS@800. Hydrocarbon-based heating mediums such as THERM-S 900 (manufactured by Nippon Steel Chemical) and 8 stone Hysol 0SAS-296 (manufactured by Nippon Petrochemical) can be mentioned;
It is possible to use two or more types of lubrication. In addition, other insulating liquids such as dialkyl ether, alkylaryl ether, diaryl ether, alkyl halide, and aryl halide may be added and mixed to these hydrocarbon compounds as necessary and used as a dispersion medium. You can also do that.

The electrorheological fluid of the present invention is obtained by mixing and dispersing the specific dispersed phase described above in a dispersion medium in the presence of a polymeric additive made of polymer (I).

The ratio of the dispersed phase to the dispersion medium in the electrorheological fluid of the present invention is preferably in the range of 50 to 500 parts by weight to 100 parts by weight of the former. If the amount of the dispersion medium exceeds 5001 parts, the shear stress obtained when an electric field is applied to the prepared electrorheological fluid may not be sufficiently large. Furthermore, if the amount of the dispersion medium is less than 50 parts by weight, the fluidity of the prepared electrorheological fluid itself may decrease, making it difficult to use it as an electrorheological fluid.

Further, the amount of the polymer additive made of polymer (I) used in the electrorheological fluid of the present invention is preferably in the range of 0.1 to 20 parts by weight per 100 parts by weight of the dispersion medium. If the amount of the polymeric additive is less than 0.1 part by weight, an electrorheological fluid with excellent dispersion stability in the absence of an applied electric field may not be obtained.

Furthermore, if the amount of the polymer additive exceeds 20 parts by weight, not only will there be no improvement in dispersion stability commensurate with the increase in the amount added, but other performances as an electrorheological fluid may be impaired. Undesirable.

The electrorheological fluid of the present invention may contain, for example, a surfactant, a polymer (I), etc., in order to adjust its viscosity or improve its shear stress.
Various conventionally known additives such as polymeric dispersants and polymeric thickeners can be added.

(Effects of the Invention) The electrorheological fluid of the present invention has excellent current characteristics in that it generates large shear stress even when a relatively weak electric field is applied, and the density of current flowing at that time is small, and the electrorheological fluid does not generate shear stress. It also has excellent stability over time in current density, low viscosity when no electric field is applied, excellent flow and mobility, and especially excellent dispersion stability in which the dispersed phase does not easily settle or float. clutch, damper,
It can be effectively used for brakes, shock absorbers, actuator valves, etc.

(Examples) The present invention will be explained below with reference to Examples, but the scope of the present invention is not limited only to these Examples.

Reference Example 1 150 t of toluene was added to a 500 ml fourth flask equipped with a stirrer, a reflux condenser, a thermometer and a 9 element inlet tube.
4-vinylpyridine 7, cog, styrene 102°5g
and 40 g of butyl methacrylate were charged, 1.5 g of azobisisobutyronitrile was added thereto, and the mixture was stirred at room temperature for 30 minutes while introducing nitrogen. Thereafter, polymerization was carried out by heating at 70° C. for 12 hours.

The solid content of the obtained toluene solution of the polymer (hereinafter referred to as polymer solution (1)) was 4.
It was 8% by weight. When the polymerization rate was measured from the residual rate of monomer, the polymerization rate of 4-vinylpyridine was 100%.
The polymerization rate of styrene was 96%, and the polymerization rate of butyl methacrylate was 100%. In addition, when the number average molecular weight of the polymer was measured using a Super System Controller GPC data processing device (manufactured by Tosoh), it was found to be 11°000.
Met.

Reference Example 2 200 g of xylene, 7.5 g of acrylonitrile, 87.5 g of styrene, and 55 g of lauryl methacrylate were charged into a 500 ml four-bottle flask equipped with a stirrer, reflux condenser, thermometer, and nitrogen inlet tube, and azobisiso 3.5 g of butyronitrile was added, and the mixture was stirred at room temperature for 30 minutes while introducing nitrogen. Thereafter, polymerization was carried out by heating at 80° C. for 12 hours.

The solid content of the resulting xylene solution of the polymer was measured and found to be 41% by weight. When the polymerization rate was measured in the same manner as in Reference Example 1, the polymerization rate of acrylonitrile was 99%.
The polymerization rate of styrene was 96%■.The number average molecular weight of the 6-polymer was measured using the same machine as Reference Example 1, and it was found to be 7.60.
It was 0.

This xylene solution of the polymer was heated at 60°C for 25 minutes under reduced pressure and the melt was distilled off, thereby producing a xylene solution of the polymer with a solid content of 55% (hereinafter referred to as polymer solution (2)). Obtained.

Reference Example 3 150g of toluene was placed in a 500° four-bottle flask equipped with a stirrer, reflux condenser, thermometer and nitrogen inlet tube.
60 g of N-vinyl-2-pyrrolidone, 60 g of p-methylstyrene, and 35 g of styrene were charged, and 08 g of azobisisobutyronitrile was added thereto, followed by stirring at room temperature for 30 minutes while introducing nitrogen. Thereafter, polymerization was carried out by heating at 60° C. for 40 hours.

The solid content of the obtained toluene solution of the polymer (hereinafter referred to as polymer solution (3)) was 5.
It was 1% by weight. When the polymerization rate was measured in the same manner as in Reference Example 1, the polymerization rate of N-vinyl-2-pyrrolidone was 100.
%, the polymerization rate of P-methylstyrene was 99%, and the polymerization rate of styrene was 100%. The number average molecular weight of the polymer was measured in the same manner as in Reference Example 1 and was found to be 160,000.

Reference Example 4 50 g of toluene, 7.5 g of N-vinylpyrrolidone, 87.5 g of styrene and 55 g of lauryl methacrylate were charged into a 500 ml four-bottle flask equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen inlet tube, and azo 0.3 g of bisisobutyronitrile was added, and the mixture was stirred at room temperature for 30 minutes while nitrogen was introduced. Thereafter, after heating at 60°C for 8 hours, polymerization was carried out by heating at 60°C for 32 hours while adding 100 g of toluene. ) was measured and found to be 5.
It was 0% by weight. When the polymerization rate was measured in the same manner as in Reference Example 1, the polymerization rate of N-vinyl-2-pyrrolidone was 100%.
The number average molecular weight of the 0 polymer, in which the polymerization rate of styrene was 99% and the polymerization rate of lauryl methacrylate was 100%, was measured in the same manner as in Reference Example 1 and found to be 410,000.

Reference Example 5 150 g of toluene was placed in a 500 ml four-hole flask equipped with a stirrer, reflux condenser, thermometer and nitrogen inlet tube.
7.5 g of 4-vinylpyridine and butyl methacrylate
), 1.5 g of azobisisobutyronitrile was added thereto, and the mixture was heated at room temperature for 30 minutes while introducing nitrogen.
Stir for 1 minute. Thereafter, polymerization was carried out by heating at 70° C. for 12 hours.

The solid content of the obtained toluene solution of the polymer (hereinafter referred to as polymer solution (5)) was 5.
It was 0% by weight. When the polymerization rate was measured from the residual rate of monomer, the polymerization rate of 4-vinylpyridine was 100%.
The polymerization rate of butyl methacrylate was 100%. Further, the number average molecular weight of the polymer was measured using a Super System Controller GPC data processing device (manufactured by Tosoh ■) and was found to be 14,000.

Example 1 A 3 000 ml four-day flask equipped with a stirrer, reflux condenser, thermometer and nitrogen inlet was charged with 12 ml of ion-exchanged water.
After adding and dissolving 16°0 g of Kuraray Bobal @ PVA-205 (■ manufactured by Kuraray, polyvinyl alcohol), 250 g of styrene, industrial divinylbenzene (manufactured by Wako Pure Chemical Industries ■, divinylbenzene 55% by weight),
A mixture of 50 g (35% by weight of ethylstyrene) and 5 g of benzoyl peroxide was added. after that,
The contents of the Itte flask were dispersed using Dispersion II (rotation speed: 2000 rpm) and heated at 70° C. for 8 hours. The obtained solid was separated, thoroughly washed with acetone and water, and then dried at 80°C for 12 hours using a hot air dryer to obtain a polymerized crosslinked product (hereinafter referred to as polymerized crosslinked product (1)). >29
1g was obtained.

Next, 100 g of this polymerized crosslinked product (1) was put into a 1,000 ml three-necked flask equipped with a stirrer, a reflux condenser, and a thermometer, and 500 g of 98% by weight sulfuric acid was added thereto under water cooling, and the mixture was stirred for 80 min. The mixture was heated at ℃ for 24 hours to carry out the sulfonation reaction. Thereafter, the contents of the flask were poured into water at 0°C, separated and washed with water.

The obtained solid was dissolved in a 10% by weight aqueous sodium hydroxide solution 3
After neutralizing with 80 ml, the solution was thoroughly washed with water.

Thereafter, it was dried at 80° C. for 10 hours using a vacuum dryer to obtain 184 g of organic polymer particles (hereinafter referred to as dispersed phase particles (1)) having an average particle diameter of 2.5 μm. In addition,
The anionic dissociative group density of the dispersed phase particles (1) is 4.2 mg
equivalent/g.

After drying 30 g of dispersed phase particles (1) at 150°C for 3 hours, the polymer solution obtained in Reference Example 1 (1) was left in a room at a temperature of 20°C and a relative humidity of 60% for 40 minutes to absorb moisture. 3g
was added to 67 g of Therm-S@900 (partially hydrogenated triphenyl manufactured by Nippon Steel Chemical Co., Ltd.) and uniformly dispersed in a dispersion medium to obtain an electrorheological fluid (1) of the present invention.

Example 2 Reference Example 2 was used instead of the polymer solution (1) in Example 1.
Using 1 g of the polymer solution (2) obtained in step 1, a mixture of 20 g of cyclohexylbenzene and 39 g of liquid paraffin (manufactured by Kanto Kagaku ■) was added instead of Therm-S@900 (partially hydrogenated triphenyl manufactured by Nippon Steel Chemical ■). The electrorheological fluid (2) of the present invention was obtained in the same manner as in Example 1 except for using the following method.

Example 3 Reference Example 3 was used instead of the polymer solution (1) in Example 1.
The same procedure as in Example 1 was carried out, except that 0.8 g of the polymer solution (3) obtained in (1) was used, and the amount of Therm-S 900 (partially hydrogenated triphenyl manufactured by Nippon Steel Chemical) was changed to 69.2 g. By the method, an electrorheological fluid (3) of the present invention was obtained.

Example 4 Reference example 4 was used instead of polymer solution (1) in Example 1.
Except that 3.5 g of the polymer solution (4) obtained in 1 was used, and a mixture of 55 g of liquid paraffin and 11.5 g of diphenyl ether was used instead of Therm-S 900 (partially hydrogenated triphenyl manufactured by Nippon Steel Chemical). is Example 1
The electrorheological fluid (4) of the present invention was obtained in the same manner as described above.

Example 5 500 equipped with reflux condenser, thermometer and nitrogen inlet tube
72 g of sodium styrene sulfonate, 8 g of N,N'-methylenebisacrylamide, 1 g of sodium persulfate, and 320 g of ion-exchanged water were placed in a three-ml parallel flask, and polymerization was carried out by heating at 70° C. for 8 hours. The obtained polymer was dried at 150° C. for 3 hours, and then pulverized and classified to obtain 46 g of organic polymer particles (hereinafter referred to as dispersed phase particles (2)) having an average particle diameter of 3.5 μm. The anionic dissociative group density of the dispersed phase particles (2) is 4.0.
mg equivalent/g.

After drying 30 g of the obtained dispersed phase particles <2) at 150°C for 3 hours, they were left in a room at a temperature of 20°C and a relative humidity of 60% for 45 minutes to absorb moisture, and then 4.8 g of the polymer solution (1) was dried. c' = in the dispersion medium obtained by adding 65.2 g of Therm-S@900 (partially hydrogenated triphenyl manufactured by Nippon Steel Chemical ■)
It was uniformly dispersed to obtain an electrorheological fluid (5) of the present invention.

Example 6 Reference Example 2 was used instead of the polymer solution (1) in Example 5.
The present invention was carried out in the same manner as in Example 5, except that 16 g of the polymer solution <2) obtained in Example 5 was used and the amount of Therm-S@900 (partially hydrogenated triphenyl manufactured by Nippon Steel Chemical) was changed to 54 g. An electrorheological fluid (6) of the invention was obtained.

Example 7 Reference Example 3 instead of polymer solution (1) in Example 5
The same method as in Example 5 was used, except that 1.5 g of the polymer solution (3) obtained in Example 5 was used, and the amount of THERM-S 0900 (partially hydrogenated triphenyl manufactured by Nippon Steel Chemical) was changed to 68°5 g. In this manner, an electrorheological fluid (7) of the present invention was obtained.

Example 8 Reference Example 4 was used instead of the polymer solution (1) in Example 5.
The same procedure as in Example 5 was carried out, except that 4.5 g of the polymer solution (4) obtained in Example 5 was used and the amount of Therm-S@900 (partially hydrogenated triphenyl manufactured by Nippon Steel Chemical) was changed to 65.5 g. By the method, an electrorheological fluid (8) of the present invention was obtained.

Comparative Example 1 Dispersed phase particles (1) 30. After drying at 150°C for 3 hours, it was left in a room at a temperature of 20°C and a relative humidity of 60% for 40 minutes to absorb moisture, and then mixed and dispersed in 70g of Therm-S 0900. Compare the fluid (1
). ) was obtained.

Comparative Example 2 After drying 30 g of dispersed phase particles (1) at 150°C for 3 hours, it was left in a room at a temperature of 20°C and a relative humidity of 60% for 40 minutes to absorb moisture. A comparative electrorheological fluid (hereinafter referred to as comparative fluid (2)) was obtained by mixing and dispersing it in the dispersion medium obtained by adding it.

Comparative Example 3 After drying 30 tons of dispersed phase particles (1) at 150°C for 3 hours, the polymer solution obtained in Reference Example 5 was left in a room at a temperature of 20°C and a relative humidity of 60% for 40 minutes to absorb moisture. (5) 3g
The mixture was dispersed in a dispersion medium obtained by adding the following to 67 g of Therm-S ■900 to obtain a comparative electrorheological fluid (hereinafter referred to as comparative fluid (3)).

Comparative Example 4 Particles with an average particle diameter of 2.5 μm were obtained by crushing and classifying commercially available silica gel (manufactured by Kanto Kagaku ■). After drying at 150℃ for 3 hours, leave it in a room at a temperature of 20'C5 and a relative humidity of 60% for 1 hour to absorb moisture.
A comparative electrorheological fluid (hereinafter referred to as comparative fluid (4)) was obtained.

Example 9 Electrorheological fluids (1) to (8) and comparative fluids (1) to (4) of the present invention obtained in Examples 1 to 8 and Comparative Examples 1 to 4
) The viscosity of each of the electrorheological fluids was measured at 23°C with no electric field applied.
A test tube with a diameter of 15 square meters was filled to a depth of 100 m from the bottom and sealed.

Thereafter, it was allowed to stand for 7 days, and the degree of sedimentation of the dispersed phase particles was observed to examine the dispersion stability of the electrorheological fluid.

The results are shown in Table 1.

In addition, each of the electrorheological fluids was put into a double cylindrical rotational viscometer with a coaxial electric field, the inner/outer cylinder gap was 1.0wn, and the shear rate was 4.
00 s”, an AC external electric field of 400 s at a temperature of 25°C.
The shear road force value (initial value) when 0 V/+m+ (frequency: 50 Hz) was applied and the current density (initial value) flowing at that time were measured. Additionally, 4000 V/r
The shear path force value (value after 3 days) and current density (value after 3 days) after continuous operation of the viscometer at 25°C for 3 days with an external electric field of m The stability over time was investigated. The results are shown in Table 1.

Table 1 As is clear from Table 1, the electrorheological fluid (1
) to (8) are excellent in current characteristics in that they generate large shear path force even when a relatively weak electric field is applied, and the current density flowing at that time is small, and the shear path force and current density that do not occur are excellent. It had excellent stability over time, and not only had a low viscosity when no electric field was applied, but also had particularly excellent dispersion stability.

On the other hand, comparative fluids (1), (2), and (3) obtained large shear path force by applying a relatively weak electric field, but had poor current characteristics and poor dispersion stability when no electric field was applied. It was inferior. Furthermore, Comparative Fluid (4) could not obtain a large shear path force when a relatively weak electric field was applied, and its stability over time and dispersion stability when no electric field was applied were also poor.

(Note 1) Dispersion stability ◎: Maintained a fairly uniform dispersion state ○: Part of the dispersed phase has settled. ×Most of the bidisperse phase sedimented

Claims (1)

[Scope of Claims] 1. An electric device containing a dispersed phase made of organic polymer particles having cation exchange ability, a dispersion medium made of an insulating liquid mainly composed of a hydrocarbon compound, and a polymer additive. It is a viscous fluid, and as a polymer additive, there are general formulas such as ▲mathematical formulas, chemical formulas, tables, etc.▼ (However, in the formula, R^1 is hydrogen or a methyl group, and X is ▲mathematical formulas, chemical formulas, tables, etc.) ▼、▲Mathematical formula, chemical formula,
There are tables, etc.▼, ▲There are mathematical formulas, chemical formulas, tables, etc.▼ or -CN. ) and the general formula ▲ mathematical formula, chemical formula, table, etc. ▼ (However, in the formula, R^2 is hydrogen or a methyl group, and Y is an aromatic hydrocarbon group.) The structural unit represented by (B
) as an essential structural unit, and the structural unit (A)
An electrorheological fluid using a polymer (I) having an average molecular weight of 10 to 10 million, in which the structural unit (B) is 0.1 to 60% by weight and the structural unit (B) is 40 to 99.9% by weight. 2. The electrorheological fluid according to claim 1, wherein the organic polymer having cation exchange ability is an organic polymer having a sulfonic acid group. 3. The electrorheological fluid according to claim 1, wherein the organic polymer having cation exchange ability is a sulfonic acid group-containing polystyrene polymer. 4. A claim in which the total content of structural units (A) and structural units (B), which are essential structural units of polymer (I) effective as a polymer additive, is 50% by weight or more of all structural units. 1
The electrorheological fluid according to any one of 3 to 3. 5. The electrorheological fluid according to any one of claims 1 to 4, wherein the amount of the polymer additive used is in the range of 0.1 to 20 parts by weight per 100 parts by weight of the dispersion medium. 6. The average particle size of the organic polymer with cation exchange ability is 0.
．． The electrorheological fluid according to any one of claims 1 to 5, having a diameter in the range of 1 to 50 μm.