JPH03192195A - Electroviscous fluid composition - Google Patents

Abstract

PURPOSE:To obtain the title composition improved in both long-term stability in shear stress and dispersion stability by dispersing specified polymer particles containing water in an insulating dispersion medium. CONSTITUTION:Crosslinked polymer particles obtained by suspension polymerization or emulsion polymerization of a monomer mixture comprising 10.0-99.9mol% vinyl aromatic compound (e.g. styrene), 0.1-90.0mol% polyvinyl compound (e.g. divinylbenzene) and, if necessary, at most 50mol% other vinyl compound (e.g. ethylene) at 50-100 deg.C are sulfonated in the absence or presence of a solvent that does not swell the particles (e.g. hexane) to give polymer particles of a mean particle diameter of 1.0-100mum which have a core-shell structure consisting of a core of a polymer having a specific gravity of 1.3 or lower and around it a crosslinked polymer of a thickness of 0.3-5.0mum having sulfo groups. 10 pts.wt. water is incorporated into 100 pts.wt. polymer particles thus obtained to give disperse phase particles. 100 pts.wt. disperse phase particles are dispersed in 50-500 pts.wt. insulating dispersion medium (e.g. polydimethylsiloxane).

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to electrorheological fluid compositions. More specifically, it is an electrorheological property that generates large shear stress even when a relatively weak electric field is applied, has excellent stability of the generated shear stress over time, and has excellent dispersion stability when no electric field is applied. The present invention relates to fluid compositions.

(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 viscoplastic type by applying an electric field change. It is a fluid whose properties change, and is generally known as a fluid exhibiting the so-called Winslow effect, in which the viscosity increases significantly and a large shear core force is induced when an external electric field is applied.

This Winslow effect has a characteristic of quick response, so electrorheological fluids can be used in clutches, dampers, brakes, etc.
Applications to shock absorbers, actuators, etc. are being attempted.

Conventionally, electrorheological fluid compositions include silicone oil,
It is known that solid particles such as cellulose, starch, soybean casein, silica gel, polystyrene ion exchange resin, cross-linked polyacrylate, etc. are dispersed in insulating oil such as diphenyl chloride or trans oil.

However, electrorheological fluid compositions using cellulose, starch, or soybean casein as a dispersed phase have a problem in that the shear core force obtained when an electric field is applied is small, The problem with electrorheological fluid compositions is that a practically sufficient shear core force cannot be induced simply by applying a relatively weak electric field.

Electrorheological fluid compositions using an alkali metal salt type ion exchange resin of polystyrene sulfonic acid, which is a type of polystyrene-based ion exchange resin, as a dispersed phase can obtain a large shear core force even when a relatively weak electric field is applied. There was a problem in that it lacked stability over time to maintain it over a long period of time.

Furthermore, since the true specific gravity of the alkali metal salt type ion exchange resin of polystyrene sulfonic acid is as high as 1.5, it was prepared using a liquid with a specific gravity of about 1.0, such as silicone oil or a hydrocarbon solvent, as a dispersion medium. In electrorheological fluid compositions,
There was a problem in that the dispersion stability was poor when no electric field was applied. Furthermore, when a halide with a large specific gravity is used as a dispersion medium, there is a problem with the toxicity of the dispersion medium.

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

Therefore, an object of the present invention is to generate a large shear core force even when a relatively weak electric field is applied and maintain it over a long period of time, which is excellent in stability over time, and which also has dispersion stability when no electric field is applied. An object of the present invention is to provide an electrorheological fluid composition having excellent properties.

(Means and effects for solving the problem) The present invention provides a structure in which a specific gravity of 0.3 to 5
．． Polymer particles having a core-shell structure with an average particle diameter in the range of 1.0 to 100 μm and having a shell made of a crosslinked polymer having a sulfonic acid group with a thickness of 0 μm, the particles 10
The present invention relates to an electrorheological fluid composition in which 10 parts by weight or less of water is contained per 0 parts by weight to form dispersed phase particles, and the dispersed phase particles are dispersed in an insulating dispersion medium.

The sulfonic acid group referred to in the present invention refers to a group that liberates a cation in the presence of a polar solvent such as water and becomes a sulfonic acid ion itself. There are no restrictions.

It is necessary that the average particle diameter of the polymer particles having a core-shell structure, which are the dispersed phase particles used in the present invention, is in the range of 1.0 to 100 μm. The average particle diameter of the dispersed phase particles is 1
．． If it is less than 0 μm, a problem arises in that a large shear core force cannot be obtained when an electric field is applied to the prepared electrorheological fluid composition. Furthermore, when the average particle diameter of the dispersed phase particles exceeds 100 μm, the shear core force value obtained when a certain electric field is applied to the prepared electrorheological fluid composition becomes irregular and difficult to stabilize. Problems arise.

It is necessary that the polymer particles serving as the dispersed phase particles used in the present invention have a shell layer of a polymeric crosslinked product having a sulfonic acid group having a thickness of 0.3 to 5.0 μm on the surface thereof. If the thickness of the surface shell layer is less than 0.3 μm, a problem arises in that a large shear core force cannot be obtained when an electric field is applied to the prepared electrorheological fluid composition. In addition, when the thickness of the surface shell layer exceeds 5.0 μm, not only no further improvement of the Winslow effect is observed by introducing sulfonic acid groups, but also the specific gravity of the dispersed phase particles becomes larger than necessary. However, a problem arises in that the prepared electrorheological fluid composition has poor dispersion stability when no electric field is applied.

The polymer particles serving as the dispersed phase particles used in the present invention need to have a core portion made of a polymer having a specific gravity of 1.3 or less. In particular, as a material constituting such a core portion, a polymer having a specific gravity in the range of 0.8 to 1.1 is preferable. When the specific gravity of the core exceeds 1.3, a problem arises in that dispersion stability cannot be obtained unless a highly toxic halide is used as a dispersion medium.

As a method for obtaining polymer particles having a core-shell structure which become dispersed phase particles used in the present invention, for example, a vinyl aromatic compound (a) and a polyvinyl compound (b) are essential components, and if necessary, other vinyl The monomer mixture (A) to which the compound (c) has been added is polymerized by a known method, and the resulting polymerized crosslinked product (I) is pulverized to an appropriate particle size as required. (I) is reacted with a sulfonating agent in the presence of a non-swelling solvent to introduce sulfonic acid groups into a range of 0.3 to 5.0 μm from the surface of the particles of polymerized crosslinked product (I). Examples include methods.

The monomer mixture (A) that can be used in the present invention has a vinyl aromatic compound (a) of 10.0 to 9
9.9 mol%, polyvinyl compound (b) 0.1-90
．． It is preferably in the range of 0 mol%. The composition ratio of the vinyl aromatic compound (a) is less than 10.0 mol%, and the composition ratio of the polyvinyl compound (b) is 90.0 mol%.
If it exceeds 100%, problems may arise in that sulfonation becomes difficult to proceed or a large shearing force cannot be obtained when an electric field is applied to an electrorheological fluid composition using the obtained particles. Further, the composition ratio of the vinyl aromatic compound (a) exceeds 99.9 mol% and the polyvinyl compound (
If the constituent ratio of b) is less than 0.1 mol %, a problem may occur in which particles adhere to each other when the crosslinked polymer obtained by polymerization is sulfonated.

Vinyl aromatic compounds (a
) include, for example, vinyl aromatic hydrocarbons such as styrene, vinylnaphthalene, vinylanthracene, and vinylphenanthrene; monoalkylstyrene compounds such as methylstyrene, ethylstyrene, propylstyrene, butylstyrene, pentylstyrene, and hexylstyrene; dimethyl Styrene, diethylstyrene, dipropylstyrene, methylethylstyrene, methylpropylstyrene,
Dialkylstyrene compounds such as methylhexylstyrene, ethylbutylstyrene, ethylpropylstyrene, ethylhexylstyrene 1, propylbutylstyrene;
Trialkylstyrene compounds such as trimethy, rustyrene, triethylstyrene, tripropylstyrene, methyldiethylstyrene, dimethylethylstyrene, methylethylpropylstyrene, methyldipropylstyrene, dimethylpropylstyrene, ethyldipropylstyrene, diethylpropylstyrene; vinylmethyl Vinyl monoalkylnaphthalene compounds such as naphthalene, vinyl ethylnaphthalene, vinylpropylnaphthalene; vinyl dialkylnaphthalene compounds such as vinyl dimethylnaphthalene, vinyl diethylnaphthalene, vinyl dipropylnaphthalene, vinyl methylethylnaphthalene; vinyl diethylnaphthalene, vinyltriethylnaphthalene, vinyl Vinyltrialkylnaphthalene compounds such as tripropylnaphthalene, vinylmethyldiethylnaphthalene, vinyldimethylethylnaphthalene, vinylmethylethylpropylnaphthalene; chlorostyrene, bromostyrene, fluorostyrene, chloromethylstyrene, chloroethylstyrene, chloropropylstyrene, chloro Dimethylstyrene, bromomethylstyrene, bromoethylstyrene, fluoromethylstyrene, fluoroethylstyrene,
Halogenated vinyl aromatic compounds such as vinyl chloronaphthalene and vinyl bromonaphthalene; methoxystyrene,
Dimethoxystyrene, trimethoxystyrene, ethoxystyrene, jetoxystyrene, triethoxystyrene, propyloxystyrene, dipropyloxystyrene, tripropyloxystyrene, phenoxystyrene,
Methoxymethylstyrene, methoxyethylstyrene, methoxypropylstyrene, ethoxymethylstyrene, ethoxyethylstyrene, propyloxymethylstyrene, propyloxyethylstyrene, phenoxymethylstyrene, phenoxyethylstyrene, methoxydimethylstyrene, methoxydiethylstyrene, phenoxydimethylstyrene, Phenoxydiethylstyrene, methoxychlorostyrene, methoxybromostyrene, vinylmethoxynaphthalene, vinyldimethoxynaphthalene, vinylethoxynaphthalene, vinyljethoxynaphthalene, vinylmethoxymethylnaphthalene, vinylmethoxydimethylnaphthalene, vinyldimethoxymethylnaphthalene, vinylmethoxyethylnaphthalene, vinyl Examples include alkoxylated or aryloxylated vinyl aromatic compounds such as methoxydiethylnaphthalene, vinyldimethoxyethylnaphthalene, vinylmethoxychloronaphthalene, and vinyldimethoxychloronaphthalene, and one or more of these may be used. can.

Polyvinyl compound (b) that can be used in the present invention
Examples include polyvinyl aromatic hydrocarbons such as divinylbenzene, divinyltoluene, divinylxylene, divinylethylbenzene, divinyldiethylbenzene, divinylpropylbenzene, divinylnaphthalene, trivinylbenzene, trivinyltoluene, trivinylxylene, trivinylnaphthalene; ethylene; glycoldi (
meth)acrylate, diethylene glycol di(meth)
Acrylate, trimethylolpropane tri(meth)
Acrylate, N,N-methylenebisacrylamide,
Examples include polyvinyl aliphatic compounds such as diallyl maleate and diallyl adipate, and one or more of these can be used.

The monomer mixture (A) in the present invention may optionally contain a vinyl aromatic compound (a) or a polyvinyl compound (b).
A vinyl compound (c) other than the above may be blended, and its composition ratio is preferably in the range of 50 mol% or less. Examples of such other vinyl compounds (C) include olefinic hydrocarbons such as ethylene, propylene, isoprene, butadiene, vinyl chloride, and chloroprene, or halogen-substituted products thereof; methyl (meth)acrylate;
Ester compounds of unsaturated carboxylic acids such as ethyl (meth)acrylate; vinyl ester compounds of monovalent carboxylic acids such as vinyl acetate and vinyl propionate; (meth)acrylamide, diacetone acrylamide, methylolated (meth)acrylamide, etc. Unsaturated amide compounds or derivatives thereof; Unsaturated cyanide compounds such as (meth)acrylonitrile and crotonitrile; (meth)
Unsaturated alcohol compounds such as allyl alcohol and croton alcohol; Unsaturated - such as (meth)acrylic acid
Basic acids: unsaturated dibasic acids such as maleic acid, fumaric acid, and itaconic acid; monoester compounds of monohydric alcohols and unsaturated dibasic acids such as monomethyl maleate and monoallyl maleate, etc. can be used, and one or more types can be used from among these.

The shape of the dispersed phase particles used in the present invention is preferably spherical or ellipsoidal. If the shape of the dispersed phase particles is other than spherical or ellipsoidal, there may be problems such as not being able to obtain a large shear core force when applying an electric field to the prepared electrorheological fluid composition, or if the electric field continues to be applied. A problem may arise in that the stability over time becomes poor in a stained state.

In the present invention, there are no particular limitations on the method for producing particles of the polymer crosslinked product (I) used as an intermediate for obtaining polymer particles having a core-shell structure, and known polymerization methods and granulation methods can be used. Just adopt it. Examples of polymerization methods include suspension polymerization, emulsion polymerization, dispersion polymerization, solution polymerization,
Examples include methods such as bulk polymerization, but preferred is a method that allows spherical or ellipsoidal particles to be easily obtained without special granulation. Therefore, suspension polymerization method and emulsion polymerization method are preferable when producing the polymerized crosslinked product (I).

When a suspension polymerization method is used to produce particles of the crosslinked polymer (I) used in the present invention, there are no particular limitations on the polymerization conditions.

Water or the like is usually used as a dispersion medium for suspension polymerization.

Dispersants for suspension polymerization are usually known such as polyvinyl alcohol, carboxymethylcellulose, ammonium salt of styrene-maleic anhydride copolymer, bentonite, sodium poly(meth)acrylate, and poly(diallylmethylammonium chloride). Things can be used.

Examples of polymerization initiators for suspension polymerization include benzoyl peroxide, tertiary butyl hydroxy peroxide, cumene peroxide, lauroyl peroxide, methyl ethyl ketone peroxide,
Peroxides such as tertiary butyl per7thaleate and caproyl peroxide; azoisobutyronitrile, azoisobutyramide, 2,2'-azo bis(2,4-dimethylmaleronitrile), azobis(α-dimethyl (valeronitrile), azobis (α-methylbutyronitrile), and the like, and one or more of these can be used.

During suspension polymerization, if necessary, a known emulsion polymerization inhibitor can be used to suppress the generation of fine particles.

Suspension polymerization is usually carried out at a temperature in the range of 50 to 100'C for about 2 to 30 hours.

For suspension polymerization, for example, water and a dispersant are charged, a mixture of monomers in which a polymerization initiator is dissolved is added to the mixture under stirring, and the particle size is controlled using a disperser or stirring device. , carried out at a predetermined temperature under suspension conditions.

When an emulsion polymerization method is used to produce particles of the crosslinked polymer (I) used in the present invention, there are no particular limitations on the polymerization conditions.

Water or the like is usually used as a solvent for emulsion polymerization.

As the emulsifier for emulsion polymerization, known ones such as surfactants such as sodium lauryl sulfonate and polyoxyethylene stearate can be used.

As the polymerization initiator for emulsion polymerization, commonly known initiators such as sodium persulfate and ammonium persulfate can be used.

Emulsion polymerization is usually carried out at a temperature in the range of 50 to 100°C for about 2 to 40 hours.

As the operation for emulsion polymerization, known methods such as seed polymerization, -temperature polymerization, monomer addition polymerization, and emulsion addition polymerization can be used.

To carry out the seed polymerization method, seed particles, water, an emulsifier, etc. are usually first put into a reaction vessel, and the mixture is uniformly dispersed with stirring, after which a part or, if necessary, all of the monomer mixture is added. Next, after heating to a predetermined temperature, a polymerization initiator is added to start the reaction. Furthermore, the remainder of the monomer mixture is added continuously or intermittently, and the process is carried out at a predetermined temperature under an emulsified state.

The polymerized crosslinked product (I) in the present invention may be a substantially non-porous polymeric crosslinked product called a gel type, and may also be a known porosity-forming agent that imparts porosity to the polymerized crosslinked product, such as a swelling agent. It may also be a porous crosslinked polymer obtained by polymerizing a monomer mixture in the coexistence of an organic solvent, a non-swelling organic solvent, a linear polymer soluble in the monomer, or a mixture thereof.

The polymer particles having a core-shell structure that serve as the dispersed phase particles used in the present invention are obtained by sulfonating the polymer crosslinked product (I) obtained by the above-described polymerization method under specific conditions.

That is, when producing polymer particles having a core-shell structure, the polymerized crosslinked product (I) is prepared in a solvent-free manner or in a polymerized crosslinked product (I).
It is necessary to carry out the sulfonation in the presence of a non-swelling solvent for I).

The non-swelling solvent for the crosslinked polymer (I) may be any solvent that does not swell the crosslinked polymer (I) and is inert to the sulfonating agent, such as hexane, cyclohexane, Examples include aliphatic hydrocarbons such as ligroin. The amount of these solvents used is preferably within the range of 1000 parts by weight or less based on 100 parts by weight of the polymeric crosslinked product (I).

When sulfonation is carried out in the absence of a solvent or in the presence of a non-swelling solvent, the sulfonic acid group is converted into a polymeric crosslinked product (I
) is introduced from the surface. Therefore, the thickness of the shell layer made of the crosslinked polymer having sulfonic acid groups can be determined mainly by adjusting the activity of the sulfonating agent, the reaction temperature, and the reaction time.

In the present invention, when a swelling solvent is used instead of the polymerized crosslinked product (I), the sulfonic acid groups are removed from the polymerized crosslinked product (I).
As a result of being rapidly introduced into the interior of I), it is impossible to form a shell layer of a predetermined thickness consisting of a polymeric crosslinked product having sulfonic acid groups.

The sulfonating agent is not particularly limited, and examples thereof include sulfuric acid, fuming sulfuric acid, chlorosulfuric acid, and the like, and one or more of these can be used.

The sulfonation reaction is usually carried out at a temperature in the range of -20 to 120°C for about 0.3 to 48 hours.

After the polymer particles having a core-shell structure obtained by sulfonating a crosslinked polymer are separated from the sulfonating agent, they are treated with a large amount of water to remove residual acids, etc. from the particles. It is advisable to wash thoroughly.Then, if necessary, the cation of the sulfonic acid group can be converted from a proton to a suitable cation species by a method such as neutralization or ion exchange.

There are no particular restrictions on the cations of the sulfonic acid group present in the polymer particles having a core-shell structure that become the dispersed phase particles used in the present invention, and include, for example, hydrogen; alkali metals such as lithium, sodium, and potassium; Alkaline earth metals such as magnesium and calcium; I such as aluminum
Group IIA metals; rVA group metals such as tin and lead; cations such as transition metals such as zinc and iron, or ammonium;
Examples include organic quaternary ammonium, pyridinium, and guadinium. One or more types can be used from among these.

The dispersed phase particles used in the present invention are obtained by incorporating water into the polymer particles having the above-mentioned core-shell structure. In the electrorheological fluid composition of the present invention, a small amount of water is contained in the dispersed phase particles, so that a large shear core force is induced when an electric field is applied.

In the present invention, the amount of water in the dispersed phase particles must be 10 parts by weight or less based on 100 parts by weight of the particles. If the amount of water exceeds 10 parts by weight, the dispersed phase particles may adhere to each other, or the insulating properties of the prepared electrorheological fluid composition may decrease, resulting in a large current flowing when an electric field is applied, which is undesirable. .

Insulating dispersion media that can be used in the present invention include:
There are no particular restrictions, and examples include silicone oils such as polydimethylsiloxane and polyphenylmethylsiloxane; hydrocarbons such as liquid paraffin, decane, dodecane, methylnaphthalene, dimethylnaphthalene, ethylnaphthalene, biphenyl, delicane, and partially hydrogenated triphenyl. ;
Ether compounds such as biphenyl ether; chlorobenzene, dichlorobenzene, trichlorobenzene, bromobenzene, dibromobenzene, chloronaphthalene, dichloronaphthalene, bromonaphthalene, chlorobiphenyl, dichlorobiphenyl, trichlorobiphenyl, bromobiphenyl, chlorodiphenylmethane, dichlorodiphenylmethane, trichlorodiphenylmethane , halogenated hydrocarbons such as bromodiphenylmethane, chlorodecane, dichlorodecane, trichlorodecane, bromodecane, chlorododecane, dichlorododecane, bromododecane;
Halogenated diphenyl ether compounds such as chlorodiphenyl ether, dichlorodiphenyl ether, trichlorodiphenyl ether, bromodiphenyl ether;
Fluorides such as Daifloil (manufactured by Daikin Industries, Ltd.) and Demnum (manufactured by Daikin Industries, Ltd.); ester compounds such as dioctyl phthalate, trioctyl trimellitate, and dibutyl sebacate; One or more of these can be used.

The electrorheological fluid composition of the present invention is made by dispersing the above-mentioned dispersed phase particles in an insulating dispersion medium, and the ratio of the dispersed phase particles to the insulating dispersion medium in the composition is 100 parts by weight of the former. The latter is preferably in the range of 50 to 500 parts by weight. If the amount of the dispersion medium exceeds 500 parts by weight, the shear core force obtained when an electric field is applied to the prepared electrorheological fluid composition may not be sufficiently large. Also,
If the amount of the dispersion medium is less than 50 parts by weight, the fluidity of the prepared composition itself may decrease, making it difficult to use it as an electrorheological fluid.

In the present invention, for example, surfactants, polymer dispersants, polymer thickeners, etc. Various additives can be added to the composition.

(Effects of the Invention) The electrorheological fluid composition of the present invention can obtain a large shear core force even when a relatively weak external electric field is applied, and has excellent stability over time of the generated shear core force. It also has excellent dispersion stability even when not in use, so it can be effectively used in clutches, dampers, brakes, shock absorbers, actuators, 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 Water 1.2! and polyvinyl alcohol (manufactured by Kuraray Co., Ltd., Kuraray Bobal PVA).
-205) After adding and dissolving 16.0g, further,
250 g of styrene.

Industrial divinylbenzene (manufactured by Wako Pure Chemical Industries, Ltd.)
A mixture consisting of 50 g (a mixture of 55% by weight of divinylbenzene, 35% by weight of ethylstyrene, etc.) and 5g of benzoyl peroxide was added. Thereafter, the contents in the flask were dispersed at a stirring speed of 600 rpm and polymerized at 80° C. for 6 hours. The obtained solid substance was filtered, thoroughly washed with water, and then dried at 80°C for 12 hours using a hot air dryer to obtain a spherical polymer crosslinked product (hereinafter referred to as polymer crosslinked product (I)). 2
85g was obtained.

The specific gravity of the polymerized crosslinked product (I) was measured using a sedimentation method and was found to be 1.05.

Reference Example 2 1.2 liters of water was charged into a 31 four-piece removable flask equipped with a stirrer, a reflux condenser, and a thermometer, and polyvinyl alcohol (manufactured by Kuraray Co., Ltd., Kuraray Bovar" PV) was added.
After adding and dissolving 10.0 g of A-205), a mixture consisting of 200 g of styrene, 50 g of N-methylstyrene, 30 g of the same industrial divinylbenzene used in Reference Example 1, and 4 g of azobisisobutyronitrile was added. added.

Thereafter, the contents in the flask were dispersed at a stirring speed of 400 rpm and polymerized at 70° C. for 8 hours. The obtained solid matter was filtered, thoroughly washed with water, and then heated to 80% by using a hot air dryer.
It was dried at ℃ for 12 hours to obtain 260 g of a spherical crosslinked polymer (hereinafter referred to as a crosslinked polymer (2)).

The specific gravity of the polymerized crosslinked product (2) was measured using a sedimentation method and found to be 1.07.

Reference Example 3 1.2 A' of water was charged into a 31 four-piece removable flask equipped with a stirrer, a reflux condenser, and a thermometer, and polyvinyl alcohol (manufactured by Kuraray Co., Ltd., Kuraray Bobal PV) was added.
After adding and dissolving 16.0 g of A-205), a mixture consisting of 250 gs of styrene, 60 g of the same industrial divinylbenzene used in Reference Example 1, 300 g of isooctane, and 12 g of azobisisobutyronitrile was added. . Thereafter, the contents in the flask were dispersed using a disperser (rotation speed: 5000 rpm) and polymerized at 70° C. for 8 hours. The obtained solid substance was filtered, thoroughly washed with acetone and water, and then dried at 80°C for 12 hours using a hot air drier. ) 290g was obtained.

The specific gravity of the polymerized crosslinked product (3) was measured using a sedimentation method and was found to be 1.04.

Reference Example 4 50 ml of water, 0.4 g of sodium lauryl sulfonate, and 1.0 g of dodecane were placed in a 300 ml four-bottle flask equipped with a stirrer, reflux condenser, thermometer, and dropping funnel.
After adding g, the mixture was emulsified using a disperser.

Furthermore, after adding 50 ml of water, 0.2 g of sodium persulfate, 40 g of styrene, and 20 g of industrial divinylbenzene, which was the same as that used in Reference Example 1, the mixture was polymerized by heating at 50° C. for 8 hours with stirring. Seed particle emulsion 160
m1 was obtained.

1.21 of water was then charged to 31 four-loop flasks equipped with a stirrer, reflux condenser, thermometer and addition funnel;
After adding 160 ml of the seed particle emulsion prepared previously and 2.8 g of sodium lauryl sulfonate, they were uniformly dispersed with stirring. After that, increase the rotation speed of the stirrer to 200 +
While maintaining the temperature at pm, the mixture was heated to 70° C. and 2 g of sodium persulfate dissolved in 10 ml of water was added. A mixture of 160 g of styrene and 80 g of industrial grade divinylbenzene as used in Reference Example 1 was then added dropwise over 18 hours. Furthermore, after reacting at the same temperature for 4 hours, the temperature was raised to 90°C and the reaction was completed 2 hours later.

The solid content of the obtained latex was separated by filtration and dried at 80°C for 12 hours using a hot air dryer to obtain a spherical crosslinked polymer (
Hereinafter, this will be referred to as a polymerized crosslinked product (4). ) 270g was obtained.

The specific gravity of the polymerized crosslinked product (4) was measured using a sedimentation method and was found to be 1.06.

Reference Example 5 1.2 liters of water was charged into a 31 four-piece removable flask equipped with a stirrer, a reflux condenser, and a thermometer, and polyvinyl alcohol (manufactured by Kuraray Co., Ltd., 7 L/Hol.
After adding and dissolving 16.0 g of PVA-205), 250 g of styrene was added.

A mixture consisting of 10 g of methoxystyrene, 40 g of the same industrial grade divinylbenzene as used in Reference Example 1, and 12 g of azobisisoisobutyronitrile was added. after that,
The contents in the flask were dispersed using a disperser (rotation speed: 3000 rpm) and polymerized at 70° C. for 9 hours.

The obtained solid was filtered, thoroughly washed with water, and then dried at 80°C for 12 hours using a hot air dryer to obtain 284 g of a spherical crosslinked polymer (hereinafter referred to as polymer crosslinked product (5)).
I got it.

The specific gravity of the polymerized crosslinked product (5) was measured using a sedimentation method and was found to be 1.06.

Example 1 1 with stirrer and thermometer! Reference Example 1
After adding 50 g of the polymer crosslinked product (I) obtained in
The mixture was stirred for a minute to form a uniform dispersion. Next, the contents of the flask were heated to 80°C and heated at the same temperature for 12 hours.
The mixture was stirred to carry out the sulfonation reaction. Thereafter, the reaction mixture was poured into 0°C water, filtered, and washed with water. The obtained solid was neutralized with 80 ml of a 10% by weight aqueous sodium hydroxide solution, and then thoroughly washed with water. Next, it was dried at 80° C. for 10 hours using a vacuum dryer to obtain 66 g of spherical dispersed phase particles (hereinafter referred to as dispersed phase particles (I)).

The average particle diameter of the obtained dispersed phase particles (I) was measured using a particle size distribution analyzer (manufactured by Shimabara Seisakusho Co., Ltd., 5ALD-1000) and found to be 50 μm. Dispersed phase particles (
The ion exchange capacity of I) was measured by neutralization titration and was found to be 2.7 equivalents/g. The specific gravity of the dispersed phase particles (I) was measured using a sedimentation method and was found to be 1.22.

The water content in the obtained dispersed phase particles (I) was measured using a Karl Fischer moisture meter (manufactured by Kyoto Electronics Industry Co., Ltd., M'PS-3P) and found to be 2.1 parts by weight.

Scanning electron microscope (manufactured by Shimadzu Corporation, EMX-8
M7) to examine the cross section of the dispersed phase particles (I) at a magnification of 1000.
When observed under magnification, an image as shown in FIG. 1 was obtained. As is clear from FIG. 1, dispersed phase particles (I)
had a core-shell structure, and the thickness of the shell layer was 4.0 μm. In addition, when we analyzed the sulfur element in the cross section of the dispersed phase particles (I) by increasing the X-ray intensity of a scanning electron microscope (1000x magnification), we found that the 2nd rI! An image as shown in J was obtained. As is clear from FIG. 2, the sulfonic acid groups in the dispersed phase particles were present only in the periphery of the particles. From the above results, it can be seen that the dispersed phase particles (I) have 4 as a shell layer.
．． It was found that it had a layer having a sulfonic acid group with a thickness of 0 μm.

30 g of the obtained dispersed phase particles (I) were mixed and dispersed in 70 g of Shin-Etsu silicone oil KF96-300C3 (dimethyl silicone oil' manufactured by Shin-Etsu Chemical Co., Ltd.),
An electrorheological fluid composition of the present invention (hereinafter referred to as fluid composition (I)) was obtained.

Example 2 500 g of 98% by weight concentrated sulfuric acid was charged into 11 four-piece removable flasks equipped with a stirrer and a thermometer, and Reference Example 1 was prepared.
After adding 50 g of the polymer crosslinked product (I) obtained in
The mixture was stirred for a minute to form a uniform dispersion. Next, the contents of the flask were heated to 80° C., and heated and stirred at the same temperature for 3 hours to perform a sulfonation reaction. Thereafter, the reaction mixture was poured into 0°C water, filtered, and washed with water. The obtained solid was neutralized with 25 ml of a 10% by weight aqueous sodium hydroxide solution, and then thoroughly washed with water. Next, using a vacuum dryer,
Dry at 80°C for 10 hours to obtain 52g of spherical dispersed phase particles (
Hereinafter, these will be referred to as dispersed phase particles (2). ) was obtained.

The average particle diameter of the obtained dispersed phase particles (2) was measured using a particle size distribution analyzer and was found to be 50 μm. The ion exchange capacity of the dispersed phase particles (2) was measured by neutralization titration and was found to be 1.0 mg equivalent/g. Dispersed phase particles (
The specific gravity of 2) was measured using a sedimentation method and was found to be 1.10.

The water content in the dispersed phase particles (2) was measured using a Karl Fischer moisture meter and was found to be 1.5 parts by weight.

When the cross section of the dispersed phase particle (2) was observed using a scanning electron microscope, it was found that the dispersed phase particle (2) also had a core-shell structure like the dispersed phase particle (I), and the shell layer was Thickness 1.0
It was found that the layer had sulfonic acid groups of μm in size.

30 g of the obtained dispersed phase particles (2) were mixed and dispersed in 70 g of Shin-Etsu silicone oil KF96-300C3 (dimethyl silicone oil manufactured by Shin-Etsu Chemical Co., Ltd.) to form the electrorheological fluid composition of the present invention (hereinafter referred to as This was obtained as fluid composition (2).

Example 3 500 g of chlorosulfuric acid was charged into 11 four-piece removable flasks equipped with a stirrer and a thermometer, and the mixture was heated to zero using a water bath.
After cooling to ℃, the polymerized crosslinked product (2) obtained in Reference Example 2
50 g was added and stirred at the same temperature for 3 hours to perform a sulfonation reaction. The reaction mixture was then poured into water at 0°C,
It was filtered and washed with water.

The obtained solid was dissolved in a 10% by weight aqueous sodium hydroxide solution 3
After neutralizing with 0ml, the solution was thoroughly washed with water. Next, using a vacuum dryer, the particles were dried at 80° C. for 10 hours, and 53 g of spherical dispersed phase particles (hereinafter referred to as dispersed phase particles (3)) were dried.

) was obtained.

The average particle diameter of the obtained dispersed phase particles (3) was measured using a particle size distribution analyzer and was found to be 80 μm. The ion exchange capacity of the dispersed phase particles (3) was measured by neutralization titration and was found to be 1.1 equivalent/g. Dispersed phase particles (3
) was measured using a sedimentation method and found to be 1.11.

The water content in the dispersed phase particles (3) was measured using a Karl Fischer moisture meter and was found to be 1.3 parts by weight.

When the cross section of the dispersed phase particle (3) was observed using a scanning electron microscope, it was found that the dispersed phase particle (3) also had a core-shell structure like the dispersed phase particle (I), and the shell layer was Thickness 1.9
It was found that the layer had sulfonic acid groups of μm in size.

30 g of the obtained dispersed phase particles (3) were mixed and dispersed in 70 g of Shin-Etsu silicone oil KF96-300C8 (dimethyl silicone oil manufactured by Shin-Etsu Chemical Co., Ltd.) to form the electrorheological fluid composition of the present invention (hereinafter referred to as Add this to the fluid composition (
3). ) was obtained.

Example 4 1! Equipped with stirrer and thermometer! Reference Example 3
After adding 50 g of the polymer crosslinked product (3) obtained in
The mixture was stirred for a minute to form a uniform dispersion. Next, the contents of the flask were heated to 80° C., and heated and stirred at the same temperature for 5 hours to perform a sulfonation reaction. Thereafter, the reaction mixture was poured into 0°C water, filtered, and washed with water. The obtained solid was neutralized with 80 ml of a 10% by weight aqueous sodium hydroxide solution, and then thoroughly washed with water. Next, it was dried at 80° C. for 10 hours using a vacuum dryer to obtain 63 g of spherical dispersed phase particles (hereinafter referred to as dispersed phase particles (4)).

The average particle diameter of the obtained dispersed phase particles (4) was measured using a particle size distribution analyzer and was found to be 10 μm. The ion exchange capacity of the dispersed phase particles (4) was measured by neutralization titration and was found to be 2.7 equivalents/g. Dispersed phase particles (4
) was measured using a sedimentation method and found to be 1.23.

The water content in the dispersed phase particles (4) was measured using a Karl Fischer moisture meter and was found to be 1.8 parts by weight.

When the cross section of the dispersed phase particle (4) was observed using a scanning electron microscope, it was found that the dispersed phase particle (4) also had a core-shell structure like the dispersed phase particle (I), and the shell layer was Thickness 0.8
It was found that the layer had sulfonic acid groups of μm in size.

30g of the obtained dispersed phase particles (4) was heated to
(Partially hydrogenated triphenyl manufactured by Nippon Steel Chemical Co., Ltd.)
The electrorheological fluid composition of the present invention (hereinafter referred to as fluid composition (4)) was obtained by mixing and dispersing it in 70 g of water.

Example 5 1 with stirrer and thermometer! 500 g of 98% by weight concentrated sulfuric acid was placed in four separable flasks, and Reference Example 4 was prepared.
After adding 50 g of the polymer crosslinked product (4) obtained in
The mixture was stirred for a minute to form a uniform dispersion. Next, the contents of the flask were heated to 80° C., and heated and stirred at the same temperature for 3 hours to perform a sulfonation reaction. Thereafter, the reaction mixture was poured into 0°C water, filtered, and washed with water. The obtained solid was neutralized with 80 ml of a 10% by weight aqueous sodium hydroxide solution, and then thoroughly washed with water. Next, using a vacuum dryer,
Dry at 80°C for 10 hours to obtain 68g of spherical dispersed phase particles (
Hereinafter, these will be referred to as dispersed phase particles (5). ) was obtained.

The average particle diameter of the obtained dispersed phase particles (5) was measured using a particle size distribution analyzer and was found to be 5 μm. The ion exchange capacity of the dispersed phase particles (5) was measured by neutralization titration and was found to be 2.6 equivalents/g. Dispersed phase particles (5)
The specific gravity was measured using a sedimentation method and was found to be 1.24.

The water content in the dispersed phase particles (5) was measured using a Karl Fischer moisture meter and was found to be 2.3 parts by weight.

When the cross section of the dispersed phase particle (5) was observed using a scanning electron microscope, it was found that the dispersed phase particle (5) also had a core-shell structure like the dispersed phase particle (I), and the shell layer was Thickness 0.4
It was found that the layer had sulfonic acid groups of μm in size.

30 g of the obtained dispersed phase particles (5) were mixed and dispersed in 7 Q g of Shin-Etsu silicone oil KF96-20C8 (dimethyl silicone oil manufactured by Shin-Etsu Chemical Co., Ltd.) to prepare the electrorheological fluid composition of the present invention (hereinafter referred to as Add this to the fluid composition (5
). ) was obtained.

Example 6 500 g of chlorosulfuric acid was charged into 11 four-piece removable flasks equipped with a stirrer and a thermometer, and the mixture was heated to zero using a water bath.
After cooling to ℃, the polymerized crosslinked product (5) obtained in Reference Example 5
50 g was added and stirred for 3 hours to form a uniform dispersion.

Next, the mixture was removed from the water bath and stirred at room temperature for 3 hours to carry out the sulfonation reaction. Thereafter, the reaction mixture was poured into 0°C water, filtered, and washed with water. The obtained solid was dissolved in 70ml of a 10% by weight lithium hydroxide aqueous solution! After neutralizing with water, it was thoroughly washed with water. Next, it was dried at 80° C. for 10 hours using a vacuum dryer to obtain 72 g of spherical dispersed phase particles (hereinafter referred to as dispersed phase particles (6)).

The average particle diameter of the obtained dispersed phase particles (6) was measured using a particle size distribution analyzer and was found to be 15 μm. The ion exchange capacity of the dispersed phase particles (6) was measured by neutralization titration and was found to be 3.6 equivalents/g. Dispersed phase particles (6
, ) was measured using a sedimentation method and found to be 1.27.

The water content of the dispersed phase particles (6) was measured using a Karl Fischer moisture meter and was found to be 2.1 parts by weight.

When the cross section of the dispersed phase particle (6) was observed using a scanning electron microscope, it was found that the dispersed phase particle (6) also had a core-shell structure like the dispersed phase particle (I), and the shell layer was Thickness 2.0
It was found that the layer had sulfonic acid groups of μm in size.

30g of the obtained dispersed phase particles (6) was heated using Therm-S 900
(Partially hydrogenated triphenyl manufactured by Nippon Steel Chemical Co., Ltd.)
The electrorheological fluid composition of the present invention (hereinafter referred to as fluid composition (6)) was obtained by mixing and dispersing it in 70 g of water.

Example 7 500 g of hexane was charged into 21 four-piece removable flasks equipped with a stirrer and a thermometer, and heated to 0° C. using a water bath.
It was cooled to Next, after adding 500 g of chlorosulfuric acid and 50 g of the polymer crosslinked product (4) obtained in Reference Example 4, 3
The mixture was stirred for a period of time to obtain a uniform dispersion. Next, the mixture was removed from the water bath and stirred at room temperature for 1 hour to carry out the sulfonation reaction.

Thereafter, the reaction mixture was poured into 0°C water, filtered, and washed with water. The obtained solid was neutralized with 140 ml of a 10% by weight aqueous potassium hydroxide solution, and then thoroughly washed with water. Then, using a vacuum dryer, it was dried at 80°C for 1.0 hours, and 76g
spherical dispersed phase particles (hereinafter referred to as dispersed phase particles (7)) were obtained.

The average particle diameter of the obtained dispersed phase particles (7) was measured using a particle size distribution analyzer and was found to be 5 μm. The ion exchange capacity of the dispersed phase particles (7) was measured by neutralization titration and was found to be 3.2 equivalents/g. Dispersed phase particles (7)
The specific gravity was measured using a sedimentation method and was found to be 1.30.

The water content of the dispersed phase particles (7) was measured using a Karl Fischer moisture meter and was found to be 2.0 parts by weight.

When the cross section of the dispersed phase particle (7) was observed using a scanning electron microscope, it was found that the dispersed phase particle (7) also had a core-shell structure like the dispersed phase particle (I), and the shell layer was °Thickness 0.
It was found that the layer had 6 μm of sulfonic acid groups.

30 g of the obtained dispersed phase particles (7) were mixed and dispersed in 70 g of Shin-Etsu silicone oil KF96-100C8 (dimethyl silicone oil manufactured by Shin-Etsu Chemical Co., Ltd.) to form the electrorheological fluid composition of the present invention (hereinafter referred to as Add this to the fluid composition (
7). ) was obtained.

Example 8 500 g of 98% by weight concentrated sulfuric acid was charged into 11 four-piece removable flasks equipped with a stirrer and a thermometer, and Reference Example 3 was prepared.
After adding 50 g of the polymer crosslinked product (3) obtained in
The mixture was stirred for a minute to form a uniform dispersion. Next, the temperature of the contents of the flask was raised to 80° C., and the mixture was heated and stirred at the same temperature for 4 hours to carry out a sulfonation reaction. Thereafter, the reaction mixture was poured into 0°C water, filtered, and washed with water. The obtained solid was neutralized with 12 g of pyridine and then thoroughly washed with water. Then,
Dry at 80°C for 10 hours using a vacuum dryer, 65g
spherical dispersed phase particles (hereinafter referred to as dispersed phase particles (8)) were obtained.

The average particle diameter of the obtained dispersed phase particles (8) was measured using a particle size distribution analyzer and found to be 10 μm. The ion exchange capacity of the dispersed phase particles (8) was measured by neutralization titration and was found to be 2.0 equivalent/g. Dispersed phase particles (8
) was measured using a sedimentation method and found to be 1.17.

The water content of the dispersed phase particles (8) was measured using a Karl Fischer moisture meter and was found to be 1.9 parts by weight.

When the cross section of the dispersed phase particle (8) was observed using a scanning electron microscope, it was found that the dispersed phase particle (8) also had a core-shell structure, similar to the dispersed phase particle (I), and had a shell layer. is thickness 0.6
It was found that the layer had sulfonic acid groups of μm in size.

30 g of the obtained dispersed phase particles (8) were mixed and dispersed in 70 g of Shin-Etsu silicone oil KF96-20C8 (dimethyl silicone oil manufactured by Shin-Etsu Chemical Co., Ltd.) to form the electrorheological fluid composition of the present invention (hereinafter referred to as Add this to the fluid composition (8
). ) was obtained.

Comparative Example 1 500 g of tetrachloroethane was charged into a 31 four-piece rosette flask equipped with a stirrer and a thermometer, and cooled while stirring. Next, 1 kg of 98% by weight concentrated sulfuric acid and 50 g of the crosslinked polymer (I) obtained in Reference Example 1 were added, followed by stirring for 30 minutes to obtain a uniform dispersion. Next, the contents of the flask were heated to 80°C and incubated at the same temperature for 2 hours.
The mixture was heated and stirred for 4 hours to carry out a sulfonation reaction. Thereafter, the reaction mixture was poured into 0°C water, filtered, and washed with water.

The obtained solid was dissolved in a 10% by weight aqueous sodium hydroxide solution 2
After neutralizing with 00 ml, the solution was thoroughly washed with water. Then, using a vacuum dryer, it was dried at 80'C for 10 hours, and 91g
spherical dispersed phase particles (hereinafter, this will be compared with dispersed phase particles (I
). ) was obtained.

The average particle diameter of the obtained comparative dispersed phase particles (I) was measured using a particle size distribution analyzer and was found to be 50 μm.

The ion exchange capacity of the comparative dispersed phase particles (I) was measured by neutralization titration and was found to be 4.5 mg equivalent/g. The specific gravity of the comparative dispersed phase particles (I) was measured using a sedimentation method and was found to be 1.52.

The water content in the comparative dispersed phase particles (I) was measured using a Karl Fischer moisture meter and was found to be 2.7 parts by weight.

When the cross section of comparative dispersed phase particles (I) was observed at a magnification of 1000 times using a scanning electron microscope, an image as shown in FIG. 3 was obtained. As is clear from FIG. 3, the comparative dispersed phase particles (I) had a uniform composition. In addition, when we analyzed the sulfur element in the cross section of the comparative dispersed phase particle (I) by increasing the X-ray intensity of a scanning electron microscope (1000x magnification), we obtained an image as shown in Figure 4. . This fourth
As is clear from the figure, the sulfonic acid groups in the dispersed phase particles were evenly present throughout the particles. From the above results, it was found that the comparative dispersed phase particles (I) had sulfonic acid groups uniformly distributed throughout the particles, similar to ordinary ion exchange resins.

30 g of the obtained comparative dispersed phase particles (I) were mixed and dispersed in 70 g of Shin-Etsu silicone oil KF96-300C3 (dimethyl silicone oil manufactured by Shin-Etsu Chemical Co., Ltd.), and a comparative electrorheological fluid composition (hereinafter referred to as , this is referred to as comparative fluid composition (I).

) was obtained.

Comparative Example 2 1 kg of 98% by weight concentrated sulfuric acid was charged into a 21-piece, four-piece removable flask equipped with a stirrer and a thermometer, and after adding 50 g of the polymerized crosslinked product (I) obtained in Reference Example 1, the mixture was stirred for 30 minutes. A uniform dispersion was obtained.

Next, the contents of the flask were heated to 80° C. and heated and stirred at the same temperature for 20 minutes to perform a sulfonation reaction. Thereafter, the reaction mixture was poured into 0°C water, filtered, and washed with water. The obtained solid was neutralized with 5 ml of a 10% by weight aqueous sodium hydroxide solution, and then thoroughly washed with water. Next, using a vacuum dryer, it was dried at 80°C for 10 hours, and 49 g of spherical dispersed phase particles (hereinafter referred to as dispersed phase particles (2) for comparison) were dried at 80°C for 10 hours.
That's what it means.

) was obtained.

The average particle diameter of the obtained comparative dispersed phase particles (2) was measured using a particle size distribution measuring device, and was found to be 50 μm.

The ion exchange capacity of the comparative dispersed phase particles (2) was measured by neutralization titration and was found to be 0.1 equivalent/g. The specific gravity of the comparative dispersed phase particles (2) was measured using a sedimentation method and was found to be 1.06.

The water content in the comparative dispersed phase particles (2) was measured using a Karl Fischer moisture meter and was found to be 0.7 parts by weight.

When the cross section of the comparative dispersed phase particle (2) was observed using a scanning electron microscope, it was found that the comparative dispersed phase particle (2) also had a core-shell structure, just like the dispersed phase particle (I). The shell layer had a thickness of 0.1 μm and had sulfonic acid groups.

30 g of the obtained comparative dispersed phase particles (2) were mixed and dispersed in 70 g of Shin-Etsu silicone oil KF96-300C3 (dimethyl silicone oil manufactured by Shin-Etsu Chemical Co., Ltd.), and a comparative electrorheological fluid composition (hereinafter referred to as , this is referred to as comparative fluid composition (2).

) was obtained.

Comparative Example 3 After drying Amberlite [phase] IR-124 (manufactured by Tokyo Organic Chemical Industry Co., Ltd.), which is a sodium polystyrene sulfonate ion-type ion exchange resin, at 150'C for 3 hours,
The mixture was pulverized and classified to obtain irregularly shaped dispersed phase particles (hereinafter referred to as comparative dispersed phase particles (3) (ion exchange capacity ffi: 4.4 mm ffi/g)).

The average particle diameter of the obtained comparative dispersed phase particles (3) was measured using a particle size distribution analyzer and was found to be 50 μm.

The specific gravity of the comparative dispersed phase particles (3) was measured using a sedimentation method and was found to be 1.51.

The water content in the comparative dispersed phase particles (3) was measured using a Karl Fischer moisture meter and was found to be 2.6 parts by weight.

30 g of the obtained comparative dispersed phase particles (3) were mixed and dispersed in 70 g of Shin-Etsu silicone oil "KF96-300C3 (dimethyl silicone oil manufactured by Shin-Etsu Chemical Co., Ltd.), and a comparative electrorheological fluid composition (hereinafter referred to as , this is referred to as comparative fluid composition (3).

) was obtained.

Example 9 Each of the fluid compositions (I) to (8) and comparative fluid compositions (I) to (3) obtained in Examples 1 to 8 and Comparative Examples 1 to 3 was placed in a test tube and heated to 25°C. The degree of sedimentation of the dispersed phase particles after standing still for one day was measured to examine the dispersion stability of the fluid composition. The results are shown in Table 1.

In addition, each of the fluid compositions was placed in a double cylindrical rotational viscometer with a coaxial electric field, and an external electric field of 4000 V was applied under the conditions of an inner/outer cylinder gap of 1.0 mm, a shear rate of 400 s, and a temperature of 25°C. The shear core force value (initial value) when /mm (frequency: 60 Hz) was applied and the current density (initial value) flowing at that time were measured. Furthermore, 4000 V/
Shear core force value after continuously operating the viscometer at 25°C for 3 days with an external electric field of mm applied (value after 3 days)
and current density (value after 3 days) were measured to examine the stability of the fluid composition over time.

The results are shown in Table 1.

No. table O: Part of the dispersed phase precipitated.

×Most of the bidisperse phase was sedimented.

(Note 2) After 3 hours, the current density is 3. 0mA/car
exceeded and became unmeasurable.

As is clear from Table 1, the fluid compositions (I) to (8) obtained in the present invention not only have excellent dispersion stability, but also have a large shear core force even when a relatively weak electric field is applied. was obtained, and its stability over time was also excellent.

On the other hand, the comparative fluid composition (I) was able to obtain a large shear core force even when a relatively weak electric field was applied, and its stability over time was also excellent, but its dispersion stability was poor. Although the comparative fluid composition (2) had excellent dispersion stability, a large shearing force could not be obtained when a relatively weak electric field was applied.

Furthermore, the comparative fluid composition (3) could not obtain a large shearing force when a relatively weak electric field was applied, had poor stability over time, and had poor dispersion stability.

[Brief explanation of drawings]

FIG. 1 is an electron micrograph showing the particle structure of the dispersed phase particles (I) obtained in Example 1. FIG. 2 is an electron micrograph showing the particle structure of the dispersed phase particles (I) for sulfur elemental analysis obtained in Example 1. FIG. 3 is an electron micrograph showing the particle structure of comparative dispersed phase particles (I) obtained in Comparative Example 1. FIG. 4 is an electron micrograph showing the particle structure of comparative dispersed phase particles (I) for sulfur elemental analysis obtained in Comparative Example 1.

Claims (1)

[Claims] 1.0.
Average particle size of 1.0 to 100 μm and having a shell made of a crosslinked polymer having sulfonic acid groups with a thickness of 3 to 5.0 μm
Polymer particles having a core-shell structure in the range of m are mixed with 10 parts by weight or less of water per 100 parts by weight of the particles to form dispersed phase particles, and the dispersed phase particles are placed in an insulating dispersion medium. An electrorheological fluid composition made by dispersing. 2. Polymer particles having a core-shell structure are made of a monomer mixture (A) containing a vinyl aromatic compound (a) and a polyvinyl compound (b) as essential components and adding other vinyl compounds (c) as necessary. Claim 1: The product is obtained by sulfonating particles of the crosslinked polymer (I) without a solvent or in the presence of a solvent that does not swell with the crosslinked polymer (I).
The electrorheological fluid composition described. 3. The constituent components of the monomer mixture (A) are 10.0 to 99
．． 9 mol% vinyl aromatic compound (a) and 0.1-90
．． 3. The electrorheological fluid composition according to claim 2, comprising 0 mol % of polyvinyl compound (b). 4. The electrorheological fluid composition according to any one of claims 1 to 3, wherein the ratio of the dispersed phase particles to the insulating dispersion medium is in the range of 50 to 500 parts by weight to 100 parts by weight of the former.